| 61. |
- Bauer, Maris, et al.
(författare)
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Terahertz detection with graphene field-effect transistors
- 2015
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Ingår i: Graphene Week 2015.
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Konferensbidrag (refereegranskat)abstract
- Detectors for quasi-optical and guide THz waves are key elements of any THz technology. In recent years, there has been much progress in their development. Notably, field-effect transistors (FETs) have been shown to be well suited for detector implementation at room temperature exploiting (self-)mixing effects in their channels [1]. They reach a typical noise-equivalent power (NEP) of several tens of pW/Hz^1/2 at 0.6 THz in CMOS and other technologies. First focal-plane arrays and cameras have been implemented. Frequency coverage to at least 5 THz has been demonstrated. Recently, this type of detection concept has been extended successfully to graphene-based FETs [2] opening the way to freely positionable THz detectors on a wide variety of substrates (also flexible plastics). We have improved the technology (see Fig. 1) [3] and reach, for GFETs on Si, an optical NEP of 150 pW/Hz^1/2 at 0.3 THz, with considerable room for improvement. An unusually strong thermoelectric contribution has been identified [2, 3] which may help to engineer enhanced detector performance.
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| 62. |
- Bauer, Maris, et al.
(författare)
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The potential for sensitivity enhancement by the thermoelectric effect in carbon-nanotube and graphene Tera-FETs
- 2015
-
Ingår i: Journal of Physics: Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 647:1, s. UNSP 012004-
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Konferensbidrag (refereegranskat)abstract
- We report on terahertz (THz) measurements with graphene field-effect transistors with integrated antennas (Tera-FETs) lay special emphasis on thermoelectric contributions to the detected THz photoresponse. Graphene Tera-FETs with integrated broad-band bow-tie antennas were fabricated in a CVD-based growth process and were successfully applied for detection at 600 GHz with optical NEPs down to 515 pW/Hz^1/2. While rectification of THz radiation by (distributed) resistive mixing of charge-density waves induced in the gated transistor channel region is well known, significant additional contributions to the detected signal have experimentally been observed and hot-carrier thermoelectric effects have been identified as a possible origin of these signals. We also observe similar signal contributions in carbonnanotube transistors.
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| 63. |
- Bazilian, Morgan, et al.
(författare)
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Open source software and crowdsourcing for energy analysis
- 2012
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Ingår i: Energy Policy. - : Elsevier BV. - 0301-4215 .- 1873-6777. ; 49, s. 149-153
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Tidskriftsartikel (refereegranskat)abstract
- Informed energy decision making requires effective software, high-quality input data, and a suitably trained user community. Developing these resources can be expensive and time consuming. Even when data and tools are intended for public re-use they often come with technical, legal, economic and social barriers that make them difficult to adopt, adapt and combine for use in new contexts. We focus on the promise of open, publically accessible software and data as well as crowdsourcing techniques to develop robust energy analysis tools that can deliver crucial, policy-relevant insight, particularly in developing countries, where planning resources are highly constrained-and the need to adapt these resources and methods to the local context is high. We survey existing research, which argues that these techniques can produce high-quality results, and also explore the potential role that linked, open data can play in both supporting the modelling process and in enhancing public engagement with energy issues.
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| 64. |
- Berkowicz, Sharon, 1994-, et al.
(författare)
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Resolving nanoscale dynamics during a liquid-liquid transition in supercooled glycerol-water solutions
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- It is proposed that a liquid-liquid transition (LLT), related to the hypothesized transition between high- and low-density liquids (HDL, LDL) in pure water, also exists in supercooled aqueous mixtures. However, experimental observations of the LLT in the supercooled solution is often complicated by the overlap with freezing. Here, we conducted an experiment probing the hypothesized LLT in deeply supercooled 16.5 mol% glycerol-water solution, combining X-ray photon correlation spectroscopy (XPCS), ultra small-angle X-ray scattering (USAXS) and wide-angle X-ray scattering (WAXS). This approach allows us to capture simultaneous, discontinuous structural and dynamic changes within the supercooled liquid following quenching to cryogenic temperatures (172-182 K). We observe changes in the inter-atomic liquid structure (from WAXS) as well as in the nanoscale structure and dynamics (from USAXS/XPCS), resembling a first-order LLT between HDL-like to LDL-like liquid. Importantly, we find that the LLT precedes the onset of ice crystalliization, which we can distinguish based on the advent of ice bragg peaks in WAXS. In addition, analysis of the two-time correlation (TTC) function from XPCS enables us to follow the dynamics during the LLT, which indicates super-diffusive ballistic-like motion and a gradual slowdown towards an arrested state upon freezing, consistent with an LLT via spinodal decomposition. We conclude that these results indicate the existence of a first-order LLT in supercooled glycerol-water solutions at intermediate glycerol concentrations, similar to that hypothesized for pure water at elevated pressures.
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| 65. |
- Bin, Maddalena, et al.
(författare)
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Coherent X-ray Scattering Reveals Nanoscale Fluctuations in Hydrated Proteins
- 2023
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Ingår i: Journal of Physical Chemistry B. - : American Chemical Society (ACS). - 1520-6106 .- 1520-5207. ; 127:21, s. 4922-4930
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Tidskriftsartikel (refereegranskat)abstract
- Hydrated proteins undergo a transition in the deeply supercooled regime, which is attributed to rapid changes in hydration water and protein structural dynamics. Here, we investigate the nanoscale stress-relaxation in hydrated lysozyme proteins stimulated and probed by X-ray Photon Correlation Spectroscopy (XPCS). This approach allows us to access the nanoscale dynamics in the deeply supercooled regime (T = 180 K), which is typically not accessible through equilibrium methods. The observed stimulated dynamic response is attributed to collective stress-relaxation as the system transitions from a jammed granular state to an elastically driven regime. The relaxation time constants exhibit Arrhenius temperature dependence upon cooling with a minimum in the Kohlrausch-Williams-Watts exponent at T = 227 K. The observed minimum is attributed to an increase in dynamical heterogeneity, which coincides with enhanced fluctuations observed in the two-time correlation functions and a maximum in the dynamic susceptibility quantified by the normalized variance χT. The amplification of fluctuations is consistent with previous studies of hydrated proteins, which indicate the key role of density and enthalpy fluctuations in hydration water. Our study provides new insights into X-ray stimulated stress-relaxation and the underlying mechanisms behind spatiotemporal fluctuations in biological granular materials.
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| 66. |
- Bode, Felix J., et al.
(författare)
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Increased numbers of motor activity peaks during light cycle are associated with reductions in adrenergic alpha(2)-receptor levels in a transgenic Huntington's disease rat model
- 2009
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Ingår i: Behavioural Brain Research. - : Elsevier BV. - 0166-4328. ; 205:1, s. 175-182
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Tidskriftsartikel (refereegranskat)abstract
- Huntington's disease (HID) is a neurodegenerative disorder caused by a CAG repeat expansion in the HD gene. Besides psychiatric, motor and cognitive symptoms, HD patients suffer from sleep disturbances. In order to screen a rat model transgenic for HD (tgHD rats) for sleep-wake cycle dysregulation, we monitored their circadian activity peaks in the present study. TgHD rats of both sexes showed hyperactivity during the dark cycle and more frequent light cycle activity peaks indicative for a disturbed sleep-wake cycle. Focusing on males at the age of 4 and 14 months, analyses of receptor levels in the hypothalamus and the basal forebrain revealed that 5-HT2A- and adrenergic alpha(2)-receptor densities in these regions were significantly altered in tgHD rats compared to their wild-type littermates. Adrenergic receptor densities correlated negatively with the light cycle hyperactivity peaks at later stages of the disease in male tgHD rats. Furthermore, reduced leptin levels, a feature associated with circadian misalignment, were present. Our study demonstrates that the male tgHD rat is a suitable model to investigate HD associated sleep alterations. Further studies are warranted to elucidate the role of adrenergic- and 5-HT2A- receptors as therapeutic targets for dysregulation of the circadian activity in HD. (C) 2009 Elsevier B.V. All rights reserved.
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| 67. |
- Boen, Rune, et al.
(författare)
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Beyond the global brain differences : intraindividual variability differences in 1q21.1 distal and 15q11.2 bp1-bp2 deletion carriers
- 2024
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Ingår i: Biological Psychiatry. - 0006-3223 .- 1873-2402. ; 95:2, s. 147-160
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Tidskriftsartikel (refereegranskat)abstract
- Background: Carriers of the 1q21.1 distal and 15q11.2 BP1-BP2 copy number variants exhibit regional and global brain differences compared with noncarriers. However, interpreting regional differences is challenging if a global difference drives the regional brain differences. Intraindividual variability measures can be used to test for regional differences beyond global differences in brain structure.Methods: Magnetic resonance imaging data were used to obtain regional brain values for 1q21.1 distal deletion (n = 30) and duplication (n = 27) and 15q11.2 BP1-BP2 deletion (n = 170) and duplication (n = 243) carriers and matched noncarriers (n = 2350). Regional intra-deviation scores, i.e., the standardized difference between an individual's regional difference and global difference, were used to test for regional differences that diverge from the global difference.Results: For the 1q21.1 distal deletion carriers, cortical surface area for regions in the medial visual cortex, posterior cingulate, and temporal pole differed less and regions in the prefrontal and superior temporal cortex differed more than the global difference in cortical surface area. For the 15q11.2 BP1-BP2 deletion carriers, cortical thickness in regions in the medial visual cortex, auditory cortex, and temporal pole differed less and the prefrontal and somatosensory cortex differed more than the global difference in cortical thickness.Conclusions: We find evidence for regional effects beyond differences in global brain measures in 1q21.1 distal and 15q11.2 BP1-BP2 copy number variants. The results provide new insight into brain profiling of the 1q21.1 distal and 15q11.2 BP1-BP2 copy number variants, with the potential to increase understanding of the mechanisms involved in altered neurodevelopment.
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| 68. |
- Cajander, Sara, 1980-, et al.
(författare)
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Profiling the dysregulated immune response in sepsis : overcoming challenges to achieve the goal of precision medicine
- 2024
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Ingår i: The Lancet Respiratory Medicine. - : Elsevier. - 2213-2600 .- 2213-2619. ; 12:4, s. 305-322
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Forskningsöversikt (refereegranskat)abstract
- Sepsis is characterised by a dysregulated host immune response to infection. Despite recognition of its significance, immune status monitoring is not implemented in clinical practice due in part to the current absence of direct therapeutic implications. Technological advances in immunological profiling could enhance our understanding of immune dysregulation and facilitate integration into clinical practice. In this Review, we provide an overview of the current state of immune profiling in sepsis, including its use, current challenges, and opportunities for progress. We highlight the important role of immunological biomarkers in facilitating predictive enrichment in current and future treatment scenarios. We propose that multiple immune and non-immune-related parameters, including clinical and microbiological data, be integrated into diagnostic and predictive combitypes, with the aid of machine learning and artificial intelligence techniques. These combitypes could form the basis of workable algorithms to guide clinical decisions that make precision medicine in sepsis a reality and improve patient outcomes.
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| 69. |
- Caraballo, Rémi, et al.
(författare)
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Triazole linker-based trivalent sialic acid inhibitors of adenovirus type 37 infection of human corneal epithelial cells
- 2015
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Ingår i: Organic and biomolecular chemistry. - 1477-0520 .- 1477-0539. ; 13:35, s. 9194-9205
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Tidskriftsartikel (refereegranskat)abstract
- Adenovirus type 37 (Ad37) is one of the principal agents responsible for epidemic keratoconjunctivitis (EKC), a severe ocular infection that remains without any available treatment. Recently, a trivalent sialic acid derivative (ME0322, Angew. Chem. Int. Ed., 2011, 50, 6519) was shown to function as a highly potent inhibitor of Ad37, efficiently preventing the attachment of the virion to the host cells and subsequent infection. Here, new trivalent sialic acid derivatives were designed, synthesized and their inhibitory properties against Ad37 infection of the human corneal epithelial cells were investigated. In comparison to ME0322, the best compound (17a) was found to be over three orders of magnitude more potent in a cell-attachment assay (IC50 = 1.4 nM) and about 140 times more potent in a cell-infection assay (IC50 = 2.9nM). X-ray crystallographic analysis demonstrated a trivalent binding mode of all compounds to the Ad37 fiber knob. For the most potent compound ophthalmic toxicity in rabbits was investigated and it was concluded that repeated eye administration did not cause any adverse effects.
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| 70. |
- Cibiraite, D., et al.
(författare)
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Thermal noise-limited sensitivity of FET-based terahertz detectors
- 2017
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Ingår i: 2017 International Conference on Noise and Fluctuations, ICNF 2017, Vilnius, Lithuania, 20-23 June 2017.
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Konferensbidrag (refereegranskat)abstract
- Here we present a detailed study on estimation of noise-dependent parameters, such as signal-to-noise ratio (SNR) or noise equivalent power (NEP), of field-effect-transistor based terahertz detectors (TeraFETs). Commonly, these parameters are estimated from a well-known assumption, that detector's performance is limited by the thermal noise of transistor's channel. However, practice shows that the influence of other noise sources or transient effects is considerable. We summarize TeraFET noise measurements performed on different material systems based transistors, such as AlGaN/GaN, AlGaAs/GaAs, silicon CMOS, and monolayer graphene. We have achieved a good agreement between thermal noise and measured data. However, attention has to be paid to gate leakage currents and slow defect charging and discharging effects, which can strongly influence TeraFET's performance estimation.
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