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- 2019
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Tidskriftsartikel (refereegranskat)
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| 8. |
- Kristan, Matej, et al.
(författare)
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The Ninth Visual Object Tracking VOT2021 Challenge Results
- 2021
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Ingår i: 2021 IEEE/CVF INTERNATIONAL CONFERENCE ON COMPUTER VISION WORKSHOPS (ICCVW 2021). - : IEEE COMPUTER SOC. - 9781665401913 ; , s. 2711-2738
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Konferensbidrag (refereegranskat)abstract
- The Visual Object Tracking challenge VOT2021 is the ninth annual tracker benchmarking activity organized by the VOT initiative. Results of 71 trackers are presented; many are state-of-the-art trackers published at major computer vision conferences or in journals in recent years. The VOT2021 challenge was composed of four sub-challenges focusing on different tracking domains: (i) VOT-ST2021 challenge focused on short-term tracking in RGB, (ii) VOT-RT2021 challenge focused on "real-time" short-term tracking in RGB, (iii) VOT-LT2021 focused on long-term tracking, namely coping with target disappearance and reappearance and (iv) VOT-RGBD2021 challenge focused on long-term tracking in RGB and depth imagery. The VOT-ST2021 dataset was refreshed, while VOT-RGBD2021 introduces a training dataset and sequestered dataset for winner identification. The source code for most of the trackers, the datasets, the evaluation kit and the results along with the source code for most trackers are publicly available at the challenge website(1).
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| 9. |
- Kristanl, Matej, et al.
(författare)
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The Seventh Visual Object Tracking VOT2019 Challenge Results
- 2019
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Ingår i: 2019 IEEE/CVF INTERNATIONAL CONFERENCE ON COMPUTER VISION WORKSHOPS (ICCVW). - : IEEE COMPUTER SOC. - 9781728150239 ; , s. 2206-2241
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Konferensbidrag (refereegranskat)abstract
- The Visual Object Tracking challenge VOT2019 is the seventh annual tracker benchmarking activity organized by the VOT initiative. Results of 81 trackers are presented; many are state-of-the-art trackers published at major computer vision conferences or in journals in the recent years. The evaluation included the standard VOT and other popular methodologies for short-term tracking analysis as well as the standard VOT methodology for long-term tracking analysis. The VOT2019 challenge was composed of five challenges focusing on different tracking domains: (i) VOT-ST2019 challenge focused on short-term tracking in RGB, (ii) VOT-RT2019 challenge focused on "real-time" short-term tracking in RGB, (iii) VOT-LT2019 focused on long-term tracking namely coping with target disappearance and reappearance. Two new challenges have been introduced: (iv) VOT-RGBT2019 challenge focused on short-term tracking in RGB and thermal imagery and (v) VOT-RGBD2019 challenge focused on long-term tracking in RGB and depth imagery. The VOT-ST2019, VOT-RT2019 and VOT-LT2019 datasets were refreshed while new datasets were introduced for VOT-RGBT2019 and VOT-RGBD2019. The VOT toolkit has been updated to support both standard short-term, long-term tracking and tracking with multi-channel imagery. Performance of the tested trackers typically by far exceeds standard baselines. The source code for most of the trackers is publicly available from the VOT page. The dataset, the evaluation kit and the results are publicly available at the challenge website(1).
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| 10. |
- Qian, Yan, et al.
(författare)
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Quantification for total demethylation potential of environmental samples utilizing the EGFP reporter gene
- 2016
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Ingår i: Journal of Hazardous Materials. - : Elsevier. - 0304-3894 .- 1873-3336. ; 306, s. 278-285
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Tidskriftsartikel (refereegranskat)abstract
- Abstract The demethylation potential of pollutants is arguably an innate component of their toxicity in environmental samples. A method was developed for determining the total demethylation potential of food samples (TDQ). The demethylation epigenetic toxicity was determined using the Hep G2 cell line transfected with pEGFP-C3 plasmids containing a methylated promoter of the EGFP reporter gene. The total demethylation potential of the sample extracts (the 5-AZA-CdR demethylation toxic equivalency) can be quantified within one week by using a standard curve of the 5-AZA-CdR demethylation agent. To explore the applicability of TDQ for environmental samples, 17 groundwater samples were collected from heavy polluted Kuihe river and the total demethylation potentials of the sample extracts were measured successfully. Meaningful demethylation toxic equivalencies ranging from 0.00050 to 0.01747 μM were found in all groundwater sample extracts. Among 19 kinds of inorganic substance, As and Cd played important roles for individual contribution to the total demethylation epigenetic toxicity. The TDQ assay is reliable and fast for quantifying the DNA demethylation potential of environmental sample extracts, which may improve epigenetic toxicity evaluations for human risk assessment, and the consistent consuming of groundwater alongside the Kuihe river pose unexpected epigenetic health risk to the local residents.
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| 11. |
- Bian, Qingzhen, 1988-, et al.
(författare)
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Vibronic coherence contributes to photocurrent generation in organic semiconductor heterojunction diodes
- 2020
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Ingår i: Nature Communications. - : NATURE PUBLISHING GROUP. - 2041-1723. ; 11:1
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Tidskriftsartikel (refereegranskat)abstract
- Charge separation dynamics after the absorption of a photon is a fundamental process relevant both for photosynthetic reaction centers and artificial solar conversion devices. It has been proposed that quantum coherence plays a role in the formation of charge carriers in organic photovoltaics, but experimental proofs have been lacking. Here we report experimental evidence of coherence in the charge separation process in organic donor/acceptor heterojunctions, in the form of low frequency oscillatory signature in the kinetics of the transient absorption and nonlinear two-dimensional photocurrent spectroscopy. The coherence plays a decisive role in the initial 200 femtoseconds as we observe distinct experimental signatures of coherent photocurrent generation. This coherent process breaks the energy barrier limitation for charge formation, thus competing with excitation energy transfer. The physics may inspire the design of new photovoltaic materials with high device performance, which explore the quantum effects in the next-generation optoelectronic applications.
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| 12. |
- Chen, Jun, et al.
(författare)
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Identifying Genetic Signatures of Natural Selection Using Pooled Population Sequencing in Picea abies
- 2016
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Ingår i: G3. - : Oxford University Press (OUP). - 2160-1836. ; 6:7, s. 1979-1989
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Tidskriftsartikel (refereegranskat)abstract
- The joint inference of selection and past demography remain a costly and demanding task. We used next generation sequencing of two pools of 48 Norway spruce mother trees, one corresponding to the Fennoscandian domain, and the other to the Alpine domain, to assess nucleotide polymorphism at 88 nuclear genes. These genes are candidate genes for phenological traits, and most belong to the photoperiod pathway. Estimates of population genetic summary statistics from the pooled data are similar to previous estimates, suggesting that pooled sequencing is reliable. The nonsynonymous SNPs tended to have both lower frequency differences and lower F-ST values between the two domains than silent ones. These results suggest the presence of purifying selection. The divergence between the two domains based on synonymous changes was around 5 million yr, a time similar to a recent phylogenetic estimate of 6 million yr, but much larger than earlier estimates based on isozymes. Two approaches, one of them novel and that considers both F-ST and difference in allele frequencies between the two domains, were used to identify SNPs potentially under diversifying selection. SNPs from around 20 genes were detected, including genes previously identified as main target for selection, such as PaPRR3 and PaGI.
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| 13. |
- Deng, Min, et al.
(författare)
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Genome-wide association analyses in Han Chinese identify two new susceptibility loci for amyotrophic lateral sclerosis
- 2013
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Ingår i: Nature Genetics. - : Nature Publishing Group. - 1061-4036 .- 1546-1718. ; 45:6, s. 697-
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Tidskriftsartikel (refereegranskat)abstract
- To identify susceptibility genes for amyotrophic lateral sclerosis (ALS), we conducted a genome-wide association study (GWAS) in 506 individuals with sporadic ALS and 1,859 controls of Han Chinese ancestry. Ninety top SNPs suggested by the current GWAS and 6 SNPs identified by previous GWAS were analyzed in an independent cohort of 706 individuals with ALS and 1,777 controls of Han Chinese ancestry. We discovered two new susceptibility loci for ALS at 1q32 (CAMK1G, rs6703183, P-combined = 2.92 x 10(-8), odds ratio (OR) = 1.31) and 22p11 (CABIN1 and SUSD2, rs8141797, P-combined = 2.35 x 10(-9), OR = 1.52). These two loci explain 12.48% of the overall variance in disease risk in the Han Chinese population. We found no association evidence for the previously reported loci in the Han Chinese population, suggesting genetic heterogeneity of disease susceptibility for ALS between ancestry groups. Our study identifies two new susceptibility loci and suggests new pathogenic mechanisms of ALS.
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| 14. |
- Hall, David, 1974-, et al.
(författare)
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Adaptive evolution of the Populus tremula photoperiod pathway
- 2011
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Ingår i: Molecular Ecology. - 0962-1083 .- 1365-294X. ; 20:7, s. 1463-1474
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Tidskriftsartikel (refereegranskat)abstract
- Environmental cues entrain the circadian clock, a core component of the photoperiod pathway in plants, to daily and seasonal changes. The circadian clock mediates input signals from light and temperature receptors to downstream target genes through feedback loops. Several studies have shown that a correct timing of the circadian system is a fitness advantage and genes in photoperiod network have been implied to evolve in response to the diversifying selection in heterogeneous environment. In an attempt to quantify the extent of the historical patterns of selection on genes in the photoperiod pathway in the widely distributed tree species European aspen (Populus tremula) we obtained sequences for twenty-five of the genes in the network and these genes were compared to patterns of nucleotide diversity in 77 randomly chosen genes from across the genome of P. tremula. We found a significant reduction in synonymous diversity in photoperiod genes while non-synonymous diversity was in line with data from control genes. A substantial fraction of the genes show signs of selection, with eight genes showing signs of rapid protein evolution. In contrast to our expectations, genes closely associated with the core circadian clock show rapid protein evolution despite their central position in the pathway. Furthermore, selection on non-synonymous mutations is negatively correlated with synonymous diversity across all genes, indicating the action of recurrent selective sweeps.
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| 15. |
- He, Sailing, et al.
(författare)
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Can Maxwell’s fish eye lens really give perfect imaging? : Part III. A careful reconsideration of the “evidence for subwavelength imaging with positive refraction”
- 2015
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Ingår i: Progress In Electromagnetics Research. - : Electromagnetics Academy. - 1070-4698 .- 1559-8985. ; 152, s. 1-15
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Tidskriftsartikel (refereegranskat)abstract
- Many scientists do not believe that Maxwell’s fish eye mirror (MFEM) can provide perfect imaging even if there is a drain array around the imaging points. However, one microwave experiment found a case where a 0.2λ resolution could be achieved in an MFEM experiment [1]. In this paper, we show that the MFEM cannot resolve two imaging points at such a subwavelength resolution in most cases even in the presence of a drain array, and an extraordinary case of subwavelength imaging requires a particular phase difference between two coherent sources. Both numerical simulations and experimental results show that the phase difference of two subwavelength-distanced coherent sources greatly influences the field distribution around the drain array. In very few cases (when the phase difference of the two sources is chosen to be a very specific value), we might resolve the image points in the drain array under the assumption that the power absorbed by the scanning cable on the left side of the drain array should be symmetric to that on the right side of the drain array [1]. However, in most cases, we cannot obtain a super-resolution imaging, as other drains around the image points will greatly influence the imaging. We also note that the experiment assumed that the power absorbed by the scanning cable on the left and the right sides of the drain array is symmetric is not correct for the experiment reported in [1], as the drain array itself is not symmetric. The highly non-symmetric distribution of the absorbed power is also verified by our simulation and experimental results. The experimental “result” of resolving two image peaks could potentially be recovered using only a single image peak, which demonstrates the wrong assumption of mirror symmetry. Comparisons and comments on perfect passive drains, “super-resolution” in a spherical geodesic waveguide, and time reverse imaging are also given.
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| 16. |
- Jiang, Qinglin, et al.
(författare)
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High Thermoelectric Performance in n-Type Perylene Bisimide Induced by the Soret Effect
- 2020
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Ingår i: Advanced Materials. - : WILEY-V C H VERLAG GMBH. - 0935-9648 .- 1521-4095. ; 32:45
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Tidskriftsartikel (refereegranskat)abstract
- Low-cost, non-toxic, abundant organic thermoelectric materials are currently under investigation for use as potential alternatives for the production of electricity from waste heat. While organic conductors reach electrical conductivities as high as their inorganic counterparts, they suffer from an overall low thermoelectric figure of merit (ZT) due to their small Seebeck coefficient. Moreover, the lack of efficient n-type organic materials still represents a major challenge when trying to fabricate efficient organic thermoelectric modules. Here, a novel strategy is proposed both to increase the Seebeck coefficient and achieve the highest thermoelectric efficiency for n-type organic thermoelectrics to date. An organic mixed ion-electron n-type conductor based on highly crystalline and reduced perylene bisimide is developed. Quasi-frozen ionic carriers yield a large ionic Seebeck coefficient of -3021 mu V K-1, while the electronic carriers dominate the electrical conductivity which is as high as 0.18 S cm(-1)at 60% relative humidity. The overall power factor is remarkably high (165 mu W m(-1)K(-2)), with aZT= 0.23 at room temperature. The resulting single leg thermoelectric generators display a high quasi-constant power output. This work paves the way for the design and development of efficient organic thermoelectrics by the rational control of the mobility of the electronic and ionic carriers.
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| 17. |
- Kamposioras, Konstantinos, et al.
(författare)
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Synthesis of Recommendations From 25 Countries and 31 Oncology Societies : How to Navigate Through Covid-19 Labyrinth
- 2020
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Ingår i: Frontiers in Oncology. - : Frontiers. - 2234-943X. ; 10
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Forskningsöversikt (refereegranskat)abstract
- Introduction: Pandemic COVID-19 is an unexpected challenge for the oncological community, indicating potential detrimental effects on cancer patients. Our aim was to summarize the converging key points providing a general guidance in order to support decision making, pertaining to the oncologic care in the middle of a global outbreak.Methods: We did an international online search in twenty five countries that have managed a surge in cancer patient numbers. We collected the recommendations from thirty one medical oncology societies.Results: By synthesizing guidelines for a) oncology service delivery adjustments, b) general and specific treatment adaptations, and c) discrepancies from guidelines comparison, we present a clinical synopsis with the forty more crucial statements. A Covid-19 risk stratification base was also created in order to obtain a quick, objective patient assessment and a risk-benefit evaluation on a case-by-case basis.Conclusions: In an attempt to face these complex needs and due to limited understanding of COVID-19, a variability of recommendations based on general epidemiological and infectious disease principles rather than definite cancer-related evidence has evolved. Additionally, the absence of an effective treatment or vaccine requires the development of cancer management guidance, capitalizing on comprehensive COVID-19 oncology experience globally.
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| 18. |
- Karki, Khadga Jung, et al.
(författare)
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Multiple exciton generation in nano-crystals revisited: Consistent calculation of the yield based on pump-probe spectroscopy.
- 2013
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 3
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Tidskriftsartikel (refereegranskat)abstract
- Multiple exciton generation (MEG) is a process in which more than one exciton is generated upon the absorption of a high energy photon, typically higher than two times the band gap, in semiconductor nanocrystals. It can be observed experimentally using time resolved spectroscopy such as the transient absorption measurements. Quantification of the MEG yield is usually done by assuming that the bi-exciton signal is twice the signal from a single exciton. Herein we show that this assumption is not always justified and may lead to significant errors in the estimated MEG yields. We develop a methodology to determine proper scaling factors to the signals from the transient absorption experiments. Using the methodology we find modest MEG yields in lead chalcogenide nanocrystals including the nanorods.
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| 19. |
- Karnahl, Michael, et al.
(författare)
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Tuning of Photocatalytic Hydrogen Production and Photoinduced Intramolecular Electron Transfer Rates by Regioselective Bridging Ligand Substitution
- 2011
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Ingår i: ChemPhysChem. - : Wiley. - 1439-4235 .- 1439-7641. ; 12:11, s. 2101-2109
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Tidskriftsartikel (refereegranskat)abstract
- Artificial photosynthesis based on supramolecular photocatalysts offers the unique possibility to study the molecular processes underlying catalytic conversion of photons into chemical fuels in great detail and to tune the properties of the photocatalyst by alterations of the molecular framework. Herein we focus on both possibilities in studying the photocatalytic reduction of protons by derivatives of the well-known photocatalyst [(tbbpy)(2)Ru(tpphz)PdCl(2)](PF(6))(2) [4,4'-di-tert-butyl-2,2'-bipyridine (tbbpy), tetrapyrido[3,2-a:2',3'-c:3 '',2 ''-h:2'", 3'"-j]phenazine (tpphz)]. We report on a modified photocatalyst where the crucial bridging ligand tpphz is substituted by bromine and investigate the effect of the structural variation on the catalytic properties of the complex and its ultrafast intramolecular charge transfer behavior. It is found that structural modification stabilizes the phenanthroline-centered metal-to-ligand charge-transfer state on the tpphz moiety, thereby reducing the electron transfer gradient across the entire electron-relaying bridging ligand and at the same time accelerating nanosecond ground-state recovery. The same structural modifications cause an overall reduction of the catalytic activity of the complex. Thus, the results highlight the potential of small structural variations in the molecular framework of supramolecular catalysts in understanding the photoinduced charge-transfer processes and optimizing their catalytic performance.
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| 20. |
- Kirkpatrick, James, et al.
(författare)
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Ultrafast Transient Optical Studies of Charge Pair Generation and Recombination in Poly-3-Hexylthiophene(P3ht):[6,6]Phenyl C61 Butyric Methyl Acid Ester (PCBM) Blend Films
- 2011
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Ingår i: The Journal of Physical Chemistry Part B. - : American Chemical Society (ACS). - 1520-5207 .- 1520-6106. ; 115:51, s. 15174-15180
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Tidskriftsartikel (refereegranskat)abstract
- Charge generation and recombination are studied in blend films of poly-3-hexylthiophene (P3HT) and [6,6']phenyl C61 butyric acid methyl ester (PCBM) using ultrafast transient absorption spectroscopy. We find that the charge generation yield depends upon both blend film composition and thermal annealing. The data suggest that recombination occurs over a wide range of time scales and that, in the least favorable cases, the fastest charge recombination occurs on a time scale similar to exciton diffusion. The results are explained using a simple model that incorporates the effect of P3HT domain size on exciton diffusion and uses empirical models of recombination kinetics. We propose our method as a route to interpretation of spectroscopic data where different processes occur on similar time scales.
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| 21. |
- Kristan, Matej, et al.
(författare)
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The first visual object tracking segmentation VOTS2023 challenge results
- 2023
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Ingår i: 2023 IEEE/CVF International conference on computer vision workshops (ICCVW). - : Institute of Electrical and Electronics Engineers Inc.. - 9798350307443 - 9798350307450 ; , s. 1788-1810
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Konferensbidrag (refereegranskat)abstract
- The Visual Object Tracking Segmentation VOTS2023 challenge is the eleventh annual tracker benchmarking activity of the VOT initiative. This challenge is the first to merge short-term and long-term as well as single-target and multiple-target tracking with segmentation masks as the only target location specification. A new dataset was created; the ground truth has been withheld to prevent overfitting. New performance measures and evaluation protocols have been created along with a new toolkit and an evaluation server. Results of the presented 47 trackers indicate that modern tracking frameworks are well-suited to deal with convergence of short-term and long-term tracking and that multiple and single target tracking can be considered a single problem. A leaderboard, with participating trackers details, the source code, the datasets, and the evaluation kit are publicly available at the challenge website1
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| 22. |
- Kristan, Matej, et al.
(författare)
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The Visual Object Tracking VOT2016 Challenge Results
- 2016
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Ingår i: COMPUTER VISION - ECCV 2016 WORKSHOPS, PT II. - Cham : SPRINGER INT PUBLISHING AG. - 9783319488813 - 9783319488806 ; , s. 777-823
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Konferensbidrag (refereegranskat)abstract
- The Visual Object Tracking challenge VOT2016 aims at comparing short-term single-object visual trackers that do not apply pre-learned models of object appearance. Results of 70 trackers are presented, with a large number of trackers being published at major computer vision conferences and journals in the recent years. The number of tested state-of-the-art trackers makes the VOT 2016 the largest and most challenging benchmark on short-term tracking to date. For each participating tracker, a short description is provided in the Appendix. The VOT2016 goes beyond its predecessors by (i) introducing a new semi-automatic ground truth bounding box annotation methodology and (ii) extending the evaluation system with the no-reset experiment.
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| 23. |
- Lan, L., et al.
(författare)
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Experimentally demonstrated a unidirectional electromagnetic cloak designed by topology optimization
- 2013
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 103:12, s. 121113-
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Tidskriftsartikel (refereegranskat)abstract
- Electromagnetic invisible devices usually designed by transformation optics are rather complicated in material parameters and not suitable for general applications. Recently, a topology optimized cloak based on level-set method was proposed to realize nearly perfect cloaking [Fujii, Appl. Phys. Lett. 102, 251106 (2013)]. In this work, we experimentally implemented this idea and fabricated a unidirectional cloak with a relative large invisible region made of single dielectric material. Good cloaking performance was verified through measurement which consists very well with numerical simulation. The advantages and disadvantages of this optimization method are also discussed.
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| 24. |
- Lenngren, Nils, et al.
(författare)
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Multiexciton Absorption Cross Sections of CdSe Nanocrystals at Band-Edge Energy
- 2013
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Ingår i: XVIIIth International Conference On Ultrafast Phenomena. - : EDP Sciences. - 2101-6275 .- 2100-014X. ; 41
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Konferensbidrag (refereegranskat)abstract
- Picosecond transient absorption signals of two kinds of cadmium selenide quantum dots were measured at various excitation intensities. The average number of excitons per quantum dot was calculated from a Poisson model, which together with kinetic parameters was used to determine exciton population kinetics. Exciton and multiexciton absorption cross sections were determined and analyzed in terms of the electronic states of the quantum dots.
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| 25. |
- Lenngren, Nils, et al.
(författare)
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Multiexciton Absorption Cross Sections of CdSe Quantum Dots Determined by Ultrafast Spectroscopy
- 2013
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Ingår i: The Journal of Physical Chemistry Letters. - : American Chemical Society (ACS). - 1948-7185. ; 4:19, s. 3330-3336
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Tidskriftsartikel (refereegranskat)abstract
- Multiexciton absorption cross sections are important for analysis of a number of experiments, including multiple exciton generation and stimulated emisson. We present a rigorous method to determine these cross sections using transient absorption (TA) measurements. We apply the method to CdSe quantum dots (QDs) and core–shell (CdSe)ZnS QDs. The method involves measuring TA dynamics for various excitation intensities over a broad time range and analyzing the experiments in terms of a kinetic multiexciton model taking into account all contributions to the signal. In this way, we were able to quantify exciton and multiexciton absorption cross sections at different spectral positions. The absorption cross sections decrease with increasing number of excitations, qualitatively in agreement with the state-filling effective mass model but showing a slower decrease. The cross sections for single-exciton to biexciton absorption range between 57 and 99% of the ground to single-exciton cross section.
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| 26. |
- Li, Wei, et al.
(författare)
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One-Step Synthesis of Precursor Oligomers for Organic Photovoltaics: A Comparative Study between Polymers and Small Molecules
- 2015
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Ingår i: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 7:49, s. 27106-27114
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Tidskriftsartikel (refereegranskat)abstract
- Two series of oligomers TQ and rhodanine end-capped TQ-DR were synthesized using a facile one-step method. Their optical, electrical, and thermal properties and photovoltaic performances were systematically investigated and compared. The TQ series of oligomers were found to be amorphous, whereas the TQ-DR series are semicrystalline. For the TQ oligomers, the results obtained in solar cells show that as the chain length of the oligomers increases, an increase in power conversion efficiency (PCE) is obtained. However, when introducing 3-ethylrhodanine into the TQ oligomers as end groups, the PCE of the TQ-DR series of oligomers decreases as the chain length increases. Moreover, the TQ-DR series of oligomers give much higher performances compared to the original amorphous TQ series of oligomers owing to the improved extinction coefficient (epsilon) and crystallinity afforded by the rhodanine. In particular, the highly crystalline oligomer TQ5-DR, which has the shortest conjugation length shows a high hole mobility of 0.034 cm(2) V-1 s(-1) and a high PCE of 3.14%, which is the highest efficiency out of all of the six oligomers. The structure-property correlations for all of the oligomers and the TQ1 polymer demonstrate that structural control of enhanced intermolecular interactions and crystallinity is a key for small molecules/oligomers to achieve high mobilities, which is an essential requirement for use in OPVs.
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| 27. |
- Liao, Xunfan, et al.
(författare)
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The role of dipole moment in two fused-ring electron acceptor and one polymer donor based ternary organic solar cells
- 2020
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Ingår i: Materials Chemistry Frontiers. - : Royal Society of Chemistry. - 2052-1537. ; 4:5, s. 1507-1518
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Tidskriftsartikel (refereegranskat)abstract
- Fused-ring electron acceptor (FREA) based ternary organic solar cells (OSCs) have made significant progress and attracted considerable attention due to their simple device architecture and broad absorption range in devices. There are three key parameters that need to be fine-tuned in ternary OSCs including absorption, energy level and morphology in order to realize high efficiencies. Herein, a series of FREAs with diverse electron-rich cores or electron-deficient terminals are developed and rationally combined to achieve high performance ternary OSCs. The dipole moment of FREAs' terminals has been unveiled as an important factor and its working mechanism has been thoroughly investigated by systematically studying six ternary OSCs. These ternary blends all exhibit complementary absorption and cascade energy levels, which can facilitate efficient light-harvesting and charge transfer. Additionally, the morphological effects on ternary OSCs are eliminated through comparative studies while demonstrating distinctively different performance. The preliminary results show that compatible dipole moment between two FREAs is critical in ternary blends. Specifically, the performance of the ternary system with two FREAs having quite different dipole moment terminals is worse compared to that with similar terminal dipole moments. The pair with larger difference in the dipole moment will also negatively impact device performance. This interesting phenomenon is likely due to the fact that very different dipole moments of terminals in FREAs can significantly decrease the electron mobility as well as induce unbalanced hole/electron transport. Consequently, it results in increased charge recombination and reduced charge collection efficiency. This finding demonstrates that the dipole moment of FREAs should be taken into account in designing ternary OSCs.
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| 28. |
- Lind, Mårten, et al.
(författare)
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A Picea abies Linkage Map Based on SNP Markers Identifies QTLs for Four Aspects of Resistance to Heterobasidion parviporum Infection
- 2014
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 9:7, s. e101049-
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Tidskriftsartikel (refereegranskat)abstract
- A consensus linkage map of Picea abies, an economically important conifer, was constructed based on the segregation of 686 SNP markers in a F-1 progeny population consisting of 247 individuals. The total length of 1889.2 cM covered 96.5% of the estimated genome length and comprised 12 large linkage groups, corresponding to the number of haploid P. abies chromosomes. The sizes of the groups (from 5.9 to 9.9% of the total map length) correlated well with previous estimates of chromosome sizes (from 5.8 to 10.8% of total genome size). Any locus in the genome has a 97% probability to be within 10 cM from a mapped marker, which makes the map suited for QTL mapping. Infecting the progeny trees with the root rot pathogen Heterobasidion parviporum allowed for mapping of four different resistance traits: lesion length at the inoculation site, fungal spread within the sapwood, exclusion of the pathogen from the host after initial infection, and ability to prevent the infection from establishing at all. These four traits were associated with two, four, four and three QTL regions respectively of which none overlapped between the traits. Each QTL explained between 4.6 and 10.1% of the respective traits phenotypic variation. Although the QTL regions contain many more genes than the ones represented by the SNP markers, at least four markers within the confidence intervals originated from genes with known function in conifer defence; a leucoanthocyanidine reductase, which has previously been shown to upregulate during H. parviporum infection, and three intermediates of the lignification process; a hydroxycinnamoyl CoA shikimate/quinate hydroxycinnamoyltransferase, a 4-coumarate CoA ligase, and a R2R3-MYB transcription factor.
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| 29. |
- Liu, Lihui, et al.
(författare)
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Ablation of ERO1A induces lethal endoplasmic reticulum stress responses and immunogenic cell death to activate anti-tumor immunity
- 2023
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Ingår i: Cell Reports Medicine. - : Cell Press. - 2666-3791. ; 4:10
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Tidskriftsartikel (refereegranskat)abstract
- Immunophenotyping of the tumor microenvironment (TME) is essential for enhancing immunotherapy effi-cacy. However, strategies for characterizing the TME exhibit significant heterogeneity. Here, we show that endoplasmic reticular oxidoreductase-1a (ERO1A) mediates an immune-suppressive TME and attenuates the response to PD-1 blockade. Ablation of ERO1A in tumor cells substantially incites anti-tumor T cell im-munity and promotes the efficacy of aPD-1 in therapeutic models. Single-cell RNA-sequencing analyses confirm that ERO1A correlates with immunosuppression and dysfunction of CD8+ T cells along anti-PD-1 treatment. In human lung cancer, high ERO1A expression is associated with a higher risk of recurrence following neoadjuvant immunotherapy. Mechanistically, ERO1A ablation impairs the balance between IRE1a and PERK signaling activities and induces lethal unfolded protein responses in tumor cells undergoing endoplasmic reticulum stress, thereby enhancing anti-tumor immunity via immunogenic cell death. These findings reveal how tumor ERO1A induces immunosuppression, highlighting its potential as a therapeutic target for cancer immunotherapy.
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| 30. |
- Liu, Lu-Chuan, et al.
(författare)
-
Improved Spatial Resolution Achieved by Chromatic Intensity Interferometry
- 2021
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 127:10
-
Tidskriftsartikel (refereegranskat)abstract
- Interferometers are widely used in imaging technologies to achieve enhanced spatial resolution, but require that the incoming photons be indistinguishable. In previous work, we built and analyzed color erasure detectors, which expand the scope of intensity interferometry to accommodate sources of different colors. Here we demonstrate experimentally how color erasure detectors can achieve improved spatial resolution in an imaging task, well beyond the diffraction limit. Utilizing two 10.9-mm- aperture telescopes and a 0.8 m baseline, we measure the distance between a 1063.6 and a 1064.4 nm source separated by 4.2 mm at a distance of 1.43 km, which surpasses the diffraction limit of a single telescope by about 40 times. Moreover, chromatic intensity interferometry allows us to recover the phase of the Fourier transform of the imaged objects-a quantity that is, in the presence of modest noise, inaccessible to conventional intensity interferometry.
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| 31. |
- Liu, Tao, et al.
(författare)
-
16% efficiency all-polymer organic solar cells enabled by a finely tuned morphology via the design of ternary blend
- 2021
-
Ingår i: Joule. - : CELL PRESS. - 2542-4351. ; 5:4, s. 914-930
-
Tidskriftsartikel (refereegranskat)abstract
- A SUMMARY There is an urgent demand for all-polymer organic solar cells (AP-OSCs) to gain higher efficiency. Here, we successfully improve the performance to 16.09% by introducing a small amount of BN-T, a B <- N-type polymer acceptor, into the PM6:PY-IT blend. It has been found that BN-T makes the active layer, based on the PM6:PY-IT:BN-T ternary blend, more crystalline but meanwhile slightly reduces the phase separation, leading to enhancement of both exciton harvesting and charge transport. From a thermodynamic viewpoint, BN-T prefers to reside between PM6 and PY-IT, and the fraction of this fine-tunes the morphology. Besides, a significantly reduced nonradiative energy loss occurs in the ternary blend, along with the coexistence of energy and charge transfer between the two acceptors. The progressive performance facilitated by these improved properties demonstrates that AP-OSCs can possibly comparably efficient with those based on small molecule acceptors, further enhancing the competitiveness of this device type.
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| 32. |
- Liu, Wei, 1977, et al.
(författare)
-
Single-Digit Nanobubble Sensing via Nanopore Technology
- 2024
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Ingår i: Analytical Chemistry. - 0003-2700 .- 1520-6882. ; 96:23, s. 9544-9550
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Tidskriftsartikel (refereegranskat)abstract
- Nanobubbles play an important role in diverse fields, including engineering, medicine, and agriculture. Understanding the characteristics of individual nanobubbles is essential for comprehending fluid dynamics behaviors and advancing nanoscale science across various fields. Here, we report a strategy based on nanopore sensors for characterizing single-digit nanobubbles. We investigated the sizes and diffusion coefficients of nanobubbles at different voltages. Additionally, the finite element simulation and molecular dynamics simulation were introduced to account for counterion concentration variation around nanobubbles in the nanopore. In particular, the differences in stability and surface charge density of nanobubbles under various solution environments have been studied by the ion-stabilized model and the DLVO theory. Additionally, a straightforward method to mitigate nanobubble generation in the bulk for reducing current noise in nanopore sensing was suggested. The results hold significant implications for enhancing the understanding of individual nanobubble characterizations, especially in the nanofluid field.
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| 33. |
- Liu, Yichao, et al.
(författare)
-
Broadband Electromagnetic Wave Tunneling with Transmuted Material Singularity
- 2020
-
Ingår i: Physical Review Letters. - : American Physical Society (APS). - 0031-9007 .- 1079-7114. ; 125:20
-
Tidskriftsartikel (refereegranskat)abstract
- Subwavelength channels filled with near-zero-index (NZI) media can realize extraordinary optical functionalities, for example, tunneling electromagnetic wave without reflections, but usually confined in a narrow wavelength band due to the material singularity (refractive index n approximate to 0), which seriously limits the practical potentials. In this Letter, we show this limit can be fundamentally overcome by an alternative, named near-zero-index-featured (NZIF) structure, with the singularity transmuted via a controlled optical conformal mapping, enabling the device implementation with nonmagnetic normal dielectrics (i.e., relative permittivity >1). Their equivalence is strictly examined through a subwavelength tunneling waveguide. Classic wave tunneling features in a broad frequency range are revealed in various confined geometries. These properties are robust against the disturbance of several kinds of structural defects benefited from the infinite effective local wavelength. The broadband and lossless NZIF medium proposed here provides a promising way to pursue the fascinating light controlling functionalities as initially enabled by singular NZI materials.
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| 34. |
- Ma, Fei, et al.
(författare)
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Association of Leukocyte Telomere Length with Mild Cognitive Impairment and Alzheimer's Disease : Role of Folate and Homocysteine
- 2019
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Ingår i: Dementia and Geriatric Cognitive Disorders. - : S. Karger AG. - 1420-8008 .- 1421-9824. ; 48:1-2, s. 56-67
-
Tidskriftsartikel (refereegranskat)abstract
- Background: Leukocyte telomere length (LTL) is associated with the aging process and age-related degenerative diseases. The relation of peripheral blood LTL to mild cognitive impairment (MCI) and Alzheimer's disease (AD) and the role of folate and homocysteine (Hcy) in this relation remain unclear.Objectives: We aimed to investigate the association between LTL and the risks of MCI/AD, and to explore whether folate and Hcy may play a role in this association.Methods: This case-control study included 129 MCI subjects, 131 AD patients and 134 healthy controls. LTL was assessed using real-time polymerase chain reaction assay. Serum folate levels were tested by chemiluminescence enzyme immunoassay, and serum Hcy levels were measured using the enzymatic cycling method. Data were analyzed using multivariate logistic regression and multivariable linear regression with adjustment for potential confounders.Results: The mean LTL was 1.56 +/- 0.25 in controls, 1.44 +/- 0.23 in MCI, and 1.28 +/- 0.28 in AD patients (p< 0.01). In multivariate logistic regression, subjects in the longest LTL tertile had lower OR for MCI (OR 0.246; 95% CI 0.101-0.597) and AD (OR 0.123; 95% CI 0.044-0.345) in comparison to subjects in the shortest tertile. Shorter LTL was dose-dependently related to the ORs of MCI and AD. Further, serum folate concentration was positively associated with LTL (p < 0.01), while serum Hcy level was negatively associated with LTL (p < 0.05). In stratified analyses, LTL-MCI/AD association varied by serum folate and Hcy level. Conclusions: Shorter LTL is associated with the risks of MCI/AD. Folate and Hcy might play an important role in this association.
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| 35. |
- Ma, Fei
(författare)
-
Dynamics and Coherent Control of Exciton-Exciton Annihilation in Aqueous J-Aggregate
- 2018
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Ingår i: The Journal of Physical Chemistry Part B. - : American Chemical Society (ACS). - 1520-5207 .- 1520-6106. ; 122:47, s. 10746-10753
-
Tidskriftsartikel (refereegranskat)abstract
- In aqueous solution of 1,1'-diethyl-2,2'-carbocyanine J-aggregate, the exciton self-trapped (EST) state is usually expected to be negligible. However, in this work, by measuring transient absorption spectroscopy under a variety of excitation fluences, the EST state was found to be formed via coherent exciton-exciton annihilation (EEA), when the excitation fluence was high enough. With the existence of a shoulder-stimulated emission band at 615 nm and a broad EST state absorption band at long wavelength, diffusion-limited and coherent EEAs can be distinguished. Adaptive coherent control was employed to check if EEA dynamics can be influenced by a shaped excitation pulse. We found that both the diffusion-limited and coherent EEAs can be suppressed. Ground-state vibronic coupling and non-Condon-type exciton-phonon coupling were discussed to explain the observations.
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| 36. |
- Ma, Fei, et al.
(författare)
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Effects of Folic Acid and Vitamin B-12, Alone and in Combination on Cognitive Function and Inflammatory Factors in the Elderly with Mild Cognitive Impairment : A Single-blind Experimental Design
- 2019
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Ingår i: Current Alzheimer Research. - : Bentham Science Publishers Ltd.. - 1567-2050 .- 1875-5828. ; 16:7, s. 622-632
-
Tidskriftsartikel (refereegranskat)abstract
- Background: Folate and vitamin B-12 are well-known as essential nutrients that play key roles in the normal functions of the brain. Inflammatory processes play at least some role in the pathology of AD. Effective nutritional intervention approaches for improving cognitive deficits that reduce the peripheral inflammatory cytokine levels have garnered special attention. Objective: The present study aimed to determine whether supplementation with folic acid and vitamin B-12, alone and in combination improves cognitive performance via reducing levels of peripheral inflammatory cytokines. Methods: 240 participants with MCI were randomly assigned in equal proportion to four treatment groups: folic acid alone, vitamin B-12 alone, folic acid plus vitamin B-12 or control without treatment daily for 6 months. Cognition was measured with WAIS-RC. The levels of inflammatory cytolcines were measured using ELISA. Changes in cognitive function or blood biomarkers were analyzed by repeated-measure analysis of variance or mixed-effects models. This trial has been registered with trial number ChiCTR-ROC-16008305. Results: Compared with control group, the folic acid plus vitamin B-12 group had significantly greater improvements in serum folate, homocysteine, vitamin B(1)(2 )and IL-6, TNF-alpha, MCP-1. The folic acid plus vitamin B-12 supplementation significantly changed the Full Scale IQ (effect size d = 0.169; P = 0.024), verbal IQ (effect size d= 0.146; P= 0.033). Information (d= 0.172; P= 0.019) and Digit Span (d= 0.187; P = 0.009) scores. Post hoc Turkey tests found that folic acid and vitamin B-12 supplementation was significantly more effective than folic acid alone for all endpoints. Conclusions: The combination of oral folic acid plus vitamin B-12 in MCI elderly for six months can significantly improve cognitive performance and reduce the levels of inflammatory cytokines in human peripheral blood. The combination of folic acid and vitamin B-12 was significantly superior to either folic acid or vitamin B-12 alone.
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| 37. |
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| 38. |
- Ma, Fei, et al.
(författare)
-
Folic acid supplementation improves cognitive function by reducing the levels of peripheral inflammatory cytokines in elderly Chinese subjects with MCI
- 2016
-
Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 6
-
Tidskriftsartikel (refereegranskat)abstract
- This study aimed to evaluate whether folic acid supplementation would improve cognitive performance by reducing serum inflammatory cytokine concentrations. This RCT was performed in Tianjin, China. Participants with mild cognitive impairment (MCI) were randomly assigned to the folic acid (400 mu g/day) or conventional treatment groups. Neuropsychological tests were administered, and folate, homocysteine, vitamin B-12, IL-6, TNF-alpha, A beta-42, and A beta-40 were measured at baseline and at 6- and 12-month time points. 152 participants (folic acid: 77, conventional: 75) completed the trial. Significant improvements in folate (eta p(2) = 0.703, P = 0.011), homocysteine (eta p(2) = 0.644, P = 0.009), A beta-42 (eta p(2) = 0.687, P = 0.013), peripheral IL-6 (eta p(2) = 0.477, P = 0.025), TNF-alpha (eta p(2) = 0.709, P = 0.009) levels were observed in folic acid group compared with conventional group. Folic acid supplementation improved the Full Scale Intelligence Quotient (P = 0.028; effect size d = 0.153), Information (P = 0.031; d = 0.157) and Digit Span (P = 0.009; d = 0.172) scores at 12 months compared with conventional treatment. Based on these findings, daily oral administration of a 400-mu g folic acid supplement to MCI subjects for 12 months can significantly improve cognitive performance and reduce peripheral inflammatory cytokine levels.
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| 39. |
- Ma, Fei, et al.
(författare)
-
Ultrafast excited state dynamics of [Cr(CO)4(bpy)] : Revealing the relaxation between triplet charge-transfer states
- 2016
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Ingår i: RSC Advances. - : Royal Society of Chemistry (RSC). - 2046-2069. ; 6:25, s. 20507-20515
-
Tidskriftsartikel (refereegranskat)abstract
- Ultrafast excited state dynamics of [Cr(CO)4(bpy)] upon metal-to-ligand charge-transfer (1MLCT) transition have been studied by pump-probe absorption spectroscopy in CH3CN, pyridine and CH2Cl2 solvents. Intersystem crossing (ISC) was found to be very fast (∼100 fs) and efficient, while the formation of the photoproduct with one axial CO dissociated is significantly less competitive, indicating a barrier along the dissociative coordinate. As a refinement of the previous dynamic model [I. R. Farrell, et al., J. Am. Chem. Soc., 1999, 121, 5296-5301], we show that a conventional downhill energy relaxation concept dominates the observed dynamics. Experimentally, we have identified the consecutive population of two triplet states as a result of triplet electronic relaxation convoluted with vibrational and solvent relaxation (the overall time is 2.7-6.9 ps depending on solvent), as well as the overall depopulation of the excited state through the lowest triplet state (57-84 ps). Adaptive excitation pulse shaping could not achieve optimization of the photoproduct quantum yield via re-distribution of only low-frequency vibrational modes during excitation, indicating that the two low-lying 1MLCT states, Cr(3d) → π∗bpy and Cr(3d) → π∗CO, are not coupled.
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| 40. |
- Ma, Fei, et al.
(författare)
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Ultrafast photoisomerization of pinacyanol : Watching an excited state reaction transiting from barrier to barrierless forms
- 2016
-
Ingår i: RSC Advances. - : Royal Society of Chemistry (RSC). - 2046-2069. ; 6:51, s. 45210-45218
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Tidskriftsartikel (refereegranskat)abstract
- Photoisomerization of 1,1′-diethyl-2,2′-carbocyanine iodide (pinacyanol) in alcohols was investigated by means of femtosecond time-resolved absorption spectroscopy. Only one out of two possible types of photoisomer was found. Viscosity-dependent kinetics indicate that the excited state dynamics consist of two parts, associated with a barrier-crossing observed in the blue side of stimulated emission (SE) and the barrierless isomerization observed in the red side of SE. These two processes occur sequentially. The blue barrier SE part is characterized by a decay lifetime (τ1, 5.2 ps in methanol) that is constant over the observed spectral region. Dependence of τ1 on solvent viscosity (η) is linear and follows Kramer's law for barrier-crossing reactions. The red barrierless part is faster and is characterized by a rise in time constants, which increases with the wavelength (τ2 λ, from 0.2 to 0.6 ps for 720-1000 nm range in methanol). τ2 λ depends on η as a fractional power function and follows BFO theory for barrierless photoisomerization. The overall photoisomerization rate is limited by the barrier-crossing rate, τ1 -1. A two-state two-mode model with a saddle-type of potential energy surface (PES) was used to explain the observed spectral dynamics. Along the stretching mode it is barrierless while along the torsion mode there is a very small barrier. As a result, the PES becomes ridge-like after displacement along the stretching coordinate. Comparing pinacyanol and 1,1′-diethyl-2,2′-cyanine iodide (1122C) with similar excited state lifetimes (5.2 vs. 4.9 ps) but quite different photoisomer quantum yields (QY, 3.6% vs. 26%, respectively), we conclude that excited state PES properties play the most important role in determining when the torsion mode couples with the stretching mode, and as a result the photoisomer QY.
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| 41. |
- Ma, Jiang-Jiang, et al.
(författare)
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Ultralow thermal conductivity and anisotropic thermoelectric performance in layered materials LaMOCh (M = Cu, Ag; Ch = S, Se)
- 2022
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Ingår i: Physical Chemistry, Chemical Physics - PCCP. - : Royal Society of Chemistry. - 1463-9076 .- 1463-9084. ; 24:35, s. 21261-21269
-
Tidskriftsartikel (refereegranskat)abstract
- In layered materials with the stacking axis perpendicular to the basal plane, anharmonicity strongly affects phonon propagation due to weak interlayer coupling, which is helpful to reduce the lattice thermal conductivity and improve the thermoelectric (TE) performance significantly. By combining first-principles calculations and the Boltzmann transport equation, we systematically analyzed and evaluated the lattice thermal conductivity and TE properties of LaMOCh (M = Cu, Ag; Ch = S, Se). The results indicate that these layered materials exhibit ultralow lattice thermal conductivities of 0.24-0.37 W m(-1) K-1 along the interlayer direction at room temperature. The low lattice thermal conductivities have been analyzed from some inherent phonon properties, such as low acoustic phonon group velocity, large Gruneisen parameters, and a short phonon relaxation time. Originating from their natural layered crystal structure, the thermal and electronic transports (i.e., thermal conductivity, Seebeck coefficient, and electrical conductivity) are both highly anisotropic between their intralayer and interlayer directions. Finally, we obtained ZT values of 1.17 and 1.26 at 900 K along the interlayer direction for n-type LaCuOSe and LaAgOSe, respectively. Generally, LaMOSe exhibit larger anisotropy than LaMOS, in both n- and p-types of doping. Our findings of low thermal conductivities and large anisotropic TE performances of these layered systems should stimulate much attention in BiCuOSe and alike layered TE families.
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| 42. |
- Ma, Ruixian, et al.
(författare)
-
BlockHammer : Improving Flash Reliability by Exploiting Process Variation Aware Proactive Failure Prediction
- 2020
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Ingår i: IEEE Transactions on Computer-Aided Design of Integrated Circuits and Systems. - : Institute of Electrical and Electronics Engineers Inc.. - 0278-0070 .- 1937-4151. ; , s. 1-1
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Tidskriftsartikel (refereegranskat)abstract
- NAND flash-based storage devices have gained a lot of popularity in recent years. Unfortunately, flash blocks suffer from limited endurance. For guaranteeing flash reliability, flash manufactures also prescribe a specified number of Program and Erase (P/E) cycles to define the endurance of flash blocks within the same chip. To extend the service lifetime of a flash-based device, existing works also assume that flash blocks have the same endurance and take P/E based wear-leveling algorithms which evenly distribute P/E cycle across flash blocks in the controller. However, many studies indicate flash blocks exhibit a wide endurance difference due to the fabrication process. The endurance of flash blocks is limited by the weakest block. Thus, the traditional P/E-based block retirement mechanism makes flash blocks underutilized. To best excavate the endurance of all blocks and improve the reliability of flash devices, we present BlockHammer, a process variation aware proactive failure prediction scheme. BlockHammer takes process variation and blocks similarity into consideration, it consists of a block classifier and a block lifetime predictor. Using machine learning technology, we first establish a block classifier to classify flash blocks into different classes. Based on the classification results, we then establish the block lifetime prediction model for different classes. Flash blocks belonging to the same class is assigned the same model. To verify the effectiveness of BlockHammer, we collect block data from a real NAND flash-based testing platform by emulating the true application scenario of NAND flash. We compare the predicted value and the tested value, the experimental results show the proposed proactive failure scheme can achieve more than 92% accuracy for flash blocks. Therefore, the block failure point can be accurately predicted using BlockHammer in advance, which greatly enhance the reliability of NAND flash. IEEE
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| 43. |
- Ma, Ruixiang, et al.
(författare)
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RBER-Aware Lifetime Prediction Scheme for 3D-TLC NAND Flash Memory
- 2019
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Ingår i: IEEE Access. - : IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. - 2169-3536. ; 7, s. 44696-44708
-
Tidskriftsartikel (refereegranskat)abstract
- NAND flash memory is widely used in various computing systems. However, flash blocks can sustain only a limited number of program/erase (P/E) cycles, which are referred to as the endurance. On one hand, in order to ensure data integrity, flash manufacturers often define the maximum P/E cycles of the worst block as the endurance of flash blocks. On the other hand, blocks exhibit large endurance variations, which introduce two serious problems. The first problem is that the error correcting code (ECC) is often over-provisioned, as it has to be designed to tolerate the worst case to ensure data integrity, which causes longer decoding latency. The second problem is the underutilized block's lifespan due to conservatively defined block endurance. Raw bit error rate (RBER) of most blocks have not arrived the allowable RBER based on the nominal endurance point, which implies that the conventional P/E cycle-based block retirement policies may waste large flash storage space. In this paper, to exploit the storage capacity of each flash block, we propose an RBER-aware lifetime prediction scheme based on machine learning technologies. We consider the problem that the model can lose prediction effectiveness over time and use incremental learning to update the model for adapting the changes at different lifetime stages. At run time, trained data will be gradually discarded, which can reduce memory overhead. For evaluating our purpose, four well-known machine learning techniques have been compared in terms of predictive accuracy and time overhead under our proposed lifetime prediction scheme. We also compared the predicted values with the tested values obtained in the real NAND flash-based test platform, and the experimental results show that the support vector machine (SVM) models based on our proposed lifetime prediction scheme can achieve as high as 95% accuracy for flash blocks. We also apply our proposed lifetime prediction scheme to predict the actual endurance of flash blocks at four different retention times, and the experimental results show that it can significantly improve the maximum P/E cycle of flash blocks from 37.5% to 86.3% on average. Therefore, the proposed lifetime prediction scheme can provide a guide for block endurance prediction.
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| 44. |
- Ma, Xiao-Fei, et al.
(författare)
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Genetic differentiation, clinal variation and phenotypic associations with growth cessation across the Populus tremula Photoperiodic Pathway
- 2010
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Ingår i: Genetics. - : Oxford University Press (OUP). - 0016-6731 .- 1943-2631. ; 186, s. 1033-1044
-
Tidskriftsartikel (refereegranskat)abstract
- Perennial plants monitor seasonal changes through changes inenvironmental conditions such as the quantity and quality oflight. To ensure a correct initiation of critical developmentalprocesses, such as the initiation and cessation of growth, plantshave adapted to a spatially variable light regime and genesin the photoperiodic pathway have been implicated as likelysources for these adaptations. Here we examine genetic variationin genes from the photoperiodic pathway in Populus tremula (Salicaceae)for signatures diversifying selection in response to varyinglight regimes across a latitudinal gradient. We fail to identifyany loci with unusually high levels of genetic differentiationamong populations despite identifying four SNPs that show significantallele frequency clines with latitude. We do, however, observelarge covariance in allelic effects across populations for growthcessation, a highly adaptive trait in P. tremula. High covariancein allelic effects is a signature compatible with diversifyingselection along an environmental gradient. We also observe significantlyhigher heterogeneity in genetic differentiation among SNPs fromthe photoperiod genes than among SNPs from randomly chosen genes.This suggests that spatially variable selection could be affectinggenes from the photoperiod pathway even if selection is notstrong enough to cause individual loci to be identified as outliers.SNPs from three genes in the photoperiod pathway (PHYB2, LHY1,and LHY2) show significant associations with natural variationin growth cessation. Collectively these SNPs explain 10–15%of the phenotypic variation in growth cessation. Covariancesin allelic effects across populations help explain an additional5–7% of the phenotypic variation in growth cessation.
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| 45. |
- Ma, Yungui, et al.
(författare)
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A transient thermal cloak experimentally realized through a rescaled diffusion equation with anisotropic thermal diffusivity
- 2013
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Ingår i: NPG Asia Materials. - : Springer Science and Business Media LLC. - 1884-4049 .- 1884-4057. ; 5:11, s. e73-
-
Tidskriftsartikel (refereegranskat)abstract
- Transformation optics has made a major contribution to the advancement of modern electromagnetism and related research assisted by the development of metamaterials. In this work, we applied this concept to the thermodynamics using the coordinate transformation to the time-dependent heat diffusion equation to manipulate the heat flux by predefined diffusion paths. Experimentally, we demonstrated a transient thermal cloaking device engineered with effective thermal materials and successfully hid a centimeter-sized vacuum cavity. A rescaled heat equation accounting for all the pertinent parameters of various ingredient materials was proposed to greatly facilitate the fabrication. Our results unambiguously demonstrate the practical possibility of implementing complex transformed thermal media with high accuracy and acquiring several unprecedented thermodynamic functions, which we believe will help to broaden the current research and pave a new path to manipulate heat for novel device applications.
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| 46. |
- Mehta, Raghav, et al.
(författare)
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QU-BraTS : MICCAI BraTS 2020 Challenge on QuantifyingUncertainty in Brain Tumor Segmentation - Analysis of Ranking Scores and Benchmarking Results
- 2022
-
Ingår i: Journal of Machine Learning for Biomedical Imaging. - 2766-905X. ; , s. 1-54
-
Tidskriftsartikel (refereegranskat)abstract
- Deep learning (DL) models have provided the state-of-the-art performance in a wide variety of medical imaging benchmarking challenges, including the Brain Tumor Segmentation (BraTS) challenges. However, the task of focal pathology multi-compartment segmentation (e.g., tumor and lesion sub-regions) is particularly challenging, and potential errors hinder the translation of DL models into clinical workflows. Quantifying the reliability of DL model predictions in the form of uncertainties, could enable clinical review of the most uncertain regions, thereby building trust and paving the way towards clinical translation. Recently, a number of uncertainty estimation methods have been introduced for DL medical image segmentation tasks. Developing scores to evaluate and compare the performance of uncertainty measures will assist the end-user in making more informed decisions. In this study, we explore and evaluate a score developed during the BraTS 2019-2020 task on uncertainty quantification (QU-BraTS), and designed to assess and rank uncertainty estimates for brain tumor multi-compartment segmentation. This score (1) rewards uncertainty estimates that produce high confidence in correct assertions, and those that assign low confidence levels at incorrect assertions, and (2) penalizes uncertainty measures that lead to a higher percentages of under-confident correct assertions. We further benchmark the segmentation uncertainties generated by 14 independent participating teams of QU-BraTS 2020, all of which also participated in the main BraTS segmentation task. Overall, our findings confirm the importance and complementary value that uncertainty estimates provide to segmentation algorithms, and hence highlight the need for uncertainty quantification in medical image analyses. Our evaluation code is made publicly available at https://github.com/RagMeh11/QU-BraTS
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| 47. |
- Meng, Fei, et al.
(författare)
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Analysis of Virgin Asphalt Brands via the Integrated Application of FTIR and Gel Permeation Chromatography
- 2020
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Ingår i: Arabian journal for science and engineering. - : Springer. - 2193-567X .- 2191-4281. ; 45, s. 7999-8009
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Tidskriftsartikel (refereegranskat)abstract
- Counterfeit asphalts have often been deliberately adulterated to reduce costs, which has seriously impeded the development of road and highway construction. In this study, attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) and gel permeation chromatography (GPC) were applied in combination to explore a fast, accurate, low-cost and efficient method to better identify the brand and quality of asphalt. Results revealed that ATR-FTIR spectra of seven brands of asphalt were basically identical, while they differ in benzene ring substituent content and (-CH2-)n (n >= 4) content. The fingerprint intervals of virgin asphalt were 1770-1636 cm-1, 1060-985 cm-1 and 920-690 cm-1. The aging degree of the same brand of asphalt was identified by 1770-1636 cm-1 and 1060-985 cm-1, while 920-690 cm-1 range was used to identify the fingerprint interval of the original asphalt brand. GPC analysis revealed that the large molecular size (LMS) content of original Fu Lian and Shuang Long asphalt brands greatly differed which were not identified by FTIR. Owing to the thermal oxidation, the LMS content of the same brand of virgin asphalt increased by 4-6% after short-term aging. The present study based on the integrated operation of GPC-FTIR for the fast and accurate recognition and distinguishing between different brands of asphalts could be of potential practical applications.
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| 48. |
- Peng, Shi-Yu, et al.
(författare)
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Reduced motor cortex GABABR function following chronic alcohol exposure
- 2021
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Ingår i: Molecular Psychiatry. - : SPRINGERNATURE. - 1359-4184 .- 1476-5578. ; 26:2, s. 383-395
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Tidskriftsartikel (refereegranskat)abstract
- The GABA(B) receptor (GABA(B)R) agonist baclofen has been used to treat alcohol and several other substance use disorders (AUD/SUD), yet its underlying neural mechanism remains unclear. The present study aimed to investigate cortical GABA(B)R dynamics following chronic alcohol exposure. Ex vivo brain slice recordings from mice chronically exposed to alcohol revealed a reduction in GABA(B)R-mediated currents, as well as a decrease of GABA(B1/2)R and G-protein-coupled inwardly rectifying potassium channel 2 (GIRK2) activities in the motor cortex. Moreover, our data indicated that these alterations could be attributed to dephosphorylation at the site of serine 783 (ser-783) in GABA(B2) subunit, which regulates the surface expression of GABA(B)R. Furthermore, a human study using paired-pulse-transcranial magnetic stimulation (TMS) analysis further demonstrated a reduced cortical inhibition mediated by GABA(B)R in patients with AUD. Our findings provide the first evidence that chronic alcohol exposure is associated with significantly impaired cortical GABA(B)R function. The ability to promote GABA(B)R signaling may account for the therapeutic efficacy of baclofen in AUD.
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| 49. |
- Qian, Chaoju, et al.
(författare)
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Population dynamics of Agriophyllum squarrosum, a pioneer annual plant endemic to mobile sand dunes, in response to global climate change
- 2016
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 6
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Tidskriftsartikel (refereegranskat)abstract
- Climate change plays an important role in the transition of ecosystems. Stratigraphic investigations have suggested that the Asian interior experienced frequent transitions between grassland and desert ecosystems as a consequence of global climate change. Using maternally and bi-parentally inherited markers, we investigated the population dynamics of Agriophyllum squarrosum (Chenopodiaceae), an annual pioneer plant endemic to mobile sand dunes. Phylogeographic analysis revealed that A. squarrosum could originate from Gurbantunggut desert since similar to 1.6 Ma, and subsequently underwent three waves of colonisation into other deserts and sandy lands corresponding to several glaciations. The rapid population expansion and distribution range shifts of A. squarrosum from monsoonal climate zones suggested that the development of the monsoonal climate significantly enhanced the population growth and gene flow of A. squarrosum. These data also suggested that desertification of the fragile grassland ecosystems in the Qinghai-Tibetan Plateau was more ancient than previously suggested and will be aggravated under global warming in the future. This study provides new molecular phylogeographic insights into how pioneer annual plant species in desert ecosystems respond to global climate change, and facilitates evaluation of the ecological potential and genetic resources of future crops for non-arable dry lands to mitigate climate change.
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- Qu, Luo-Yuan, et al.
(författare)
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Chromatic interferometry with small frequency differences
- 2020
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Ingår i: Optics Express. - 1094-4087. ; 28:22, s. 32294-32301
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Tidskriftsartikel (refereegranskat)abstract
- By developing a 'two-crystal' method for color erasure, we can broaden the scope of chromatic interferometry to include optical photons whose frequency difference falls outside of the 400 nm to 4500 nm wavelength range, which is the passband of a PPLN crystal. We demonstrate this possibility experimentally, by observing interference patterns between sources at 1064.4 nm and 1063.6 nm, corresponding to a frequency difference of about 200 GHz.
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