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| 2. |
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| 3. |
- Duan, Chunhui, et al.
(författare)
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Improving Performance of All-Polymer Solar Cells Through Backbone Engineering of Both Donors and Acceptors
- 2018
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Ingår i: Solar RRL. - : Wiley. - 2367-198X. ; 2:12
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Tidskriftsartikel (refereegranskat)abstract
- All-polymer solar cells (APSCs), composed of semiconducting donor and acceptor polymers, have attracted considerable attention due to their unique advantages compared to polymer-fullerene-based devices in terms of enhanced light absorption and morphological stability. To improve the performance of APSCs, the morphology of the active layer must be optimized. By employing a random copolymerization strategy to control the regularity of the backbone of the donor polymers (PTAZ-TPDx) and acceptor polymers (PNDI-Tx) the morphology can be systematically optimized by tuning the polymer packing and crystallinity. To minimize effects of molecular weight, both donor and acceptor polymers have number-average molecular weights in narrow ranges. Experimental and coarse-grained modeling results disclose that systematic backbone engineering greatly affects the polymer crystallinity and ultimately the phase separation and morphology of the all-polymer blends. Decreasing the backbone regularity of either the donor or the acceptor polymer reduces the local crystallinity of the individual phase in blend films, affording reduced short-circuit current densities and fill factors. This two-dimensional crystallinity optimization strategy locates a PCE maximum at highest crystallinity for both donor and acceptor polymers. Overall, this study demonstrates that proper control of both donor and acceptor polymer crystallinity simultaneously is essential to optimize APSC performance.
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| 4. |
- Gerritsen, Bart H. M., et al.
(författare)
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Social Media Coming to the Mall : A Cross-Channel Response
- 2014. - 1
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Ingår i: <em></em>Product Development in the Socio-sphere. - Cham : Springer. - 9783319074030 - 9783319074047 ; , s. 169-235
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Bokkapitel (refereegranskat)abstract
- Traditional shopping malls experience the effects of expanding online shopping. In addition, social media grew as a platform for customer orientation and expression. In-mall retail must respond. We take the customer journey as the guiding model for customer experience building and focus on converting cross-channel built customer expectation into enriched customer experiences in in-mall stores. We focus on the in-mall part of the journey but recognize the need to engage with customers in other parts of the journey and on social media. That is where the word-of-mouth spreads nowadays. We develop a ‘u-retail’ process model and a cyber-physical system concept for a mall: we combine a mall website, mobile apps and interactive storefronts containing Facebook processes into an integrating system. Customers can manipulate info and processes displayed on the interactive storefront through touch or mobile devices. The Facebook shopping-with-online-friends process inserts real-time feedback from social media friends in the storefront window. We show how ‘gamification’ and trust and loyalty breeding can be employed. Mall and retailers attract customers in a collective manner, from parking services to package deals. Cross-channel customer tracking is part of the concept, providing a view on both online and offline communities. Ubiquitous tracking of customers foster deep customer relation and experience of data. We implemented a first partly surrogate prototype to validate the concept. This partly empirical, partly designed experimental implementation can itself be a big data tool for scientists and retailers to acquire deeper insights. The concept can be generalized to other social contexts. © Springer International Publishing Switzerland 2014
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| 5. |
- Gurvits, L. I., et al.
(författare)
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The science case and challenges of spaceborne sub-millimeter interferometry: the study case of TeraHertz Exploration and Zooming-in for Astrophysics (THEZA)
- 2021
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Ingår i: Proceedings of the International Astronautical Congress, IAC. - 0074-1795. ; A7
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Konferensbidrag (refereegranskat)abstract
- Ultra-high angular resolution in astronomy has always been an important vehicle for making fundamental discoveries. Recent results in direct imaging of the vicinity of the super-massive black hole in the nucleus of the radio galaxy M87 by the millimeter VLBI system Event Horizon Telescope (EHT) and various pioneering results of the Space VLBI mission RadioAstron provided new momentum in high angular resolution astrophysics. In both mentioned cases, the angular resolution reached the values of about 10−20 microrcseconds (0.05−0.1 nanoradian). Angular resolution is proportional to the observing wavelength and inversely proportional to the interferometer baseline length. In the case of Earth-based EHT, the highest angular resolution was achieved by combining the shortest possible wavelength of 1.3 mm with the longest possible baselines, comparable to the Earth’s diameter. For RadioAstron, operational wavelengths were in the range from 92 cm down to 1.3 cm, but the baselines were as long as ∼350,000 km. However, these two highlights of radio astronomy, EHT and RadioAstron do not”saturate” the interest to further increase in angular resolution. Quite opposite: the science case for further increase in angular resolution of astrophysical studies becomes even stronger. A natural and, in fact, the only possible way of moving forward is to enhance mm/sub-mm VLBI by extending baselines to extraterrestrial dimensions, i.e. creating a mm/sub-mm Space VLBI system. The inevitable move toward space-borne mm/sub-mm VLBI is a subject of several concept studies. In this presentation we will focus on one of them called TeraHertz Exploration and Zooming-in for Astrophysics (THEZA), prepared in response to the ESA’s call for its next major science program Voyage 2050 (Gurvits et al. 2021). The THEZA rationale is focused at the physics of spacetime in the vicinity of super-massive black holes as the leading science drive. However, it will also open up a sizable new range of hitherto unreachable parameters of observational radio astrophysics and create a multi-disciplinary scientific facility and offer a high degree of synergy with prospective “single dish” space-borne sub-mm astronomy (e.g., Wiedner et al. 2021) and infrared interferometry (e.g., Linz et al. 2021). As an amalgam of several major trends of modern observational astrophysics, THEZA aims at facilitating a breakthrough in high-resolution high image quality astronomical studies.
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| 6. |
- Gurvits,, et al.
(författare)
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The science case and challenges of space-borne sub-millimeter interferometry
- 2022
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Ingår i: Acta Astronautica. - : Elsevier BV. - 0094-5765. ; 196, s. 314-333
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Tidskriftsartikel (refereegranskat)abstract
- Ultra-high angular resolution in astronomy has always been an important vehicle for making fundamental discoveries. Recent results in direct imaging of the vicinity of the supermassive black hole in the nucleus of the radio galaxy M87 by the millimeter VLBI system Event Horizon Telescope and various pioneering results of the Space VLBI mission RadioAstron provided new momentum in high angular resolution astrophysics. In both mentioned cases, the angular resolution reached the values of about 10???20 microarcseconds (0.05???0.1 nanoradian). Further developments towards at least an order of magnitude ???sharper???values, at the level of 1 microarcsecond are dictated by the needs of advanced astrophysical studies. The paper emphasis that these higher values can only be achieved by placing millimeter and submillimeter wavelength interferometric systems in space. A concept of such the system, called Terahertz Exploration and Zooming-in for Astrophysics, has been proposed in the framework of the ESA Call for White Papers for the Voyage 2050 long term plan in 2019. In the current paper we present new science objectives for such the concept based on recent results in studies of active galactic nuclei and supermassive black holes. We also discuss several approaches for addressing technological challenges of creating a millimeter/sub-millimeter wavelength interferometric system in space. In particular, we consider a novel configuration of a space-borne millimeter/sub-millimeter antenna which might resolve several bottlenecks in creating large precise mechanical structures. The paper also presents an overview of prospective space-qualified technologies of low-noise analogue front-end instrumentation for millimeter/sub-millimeter telescopes. Data handling and processing instrumentation is another key technological component of a sub-millimeter Space VLBI system. Requirements and possible implementation options for this instrumentation are described as an extrapolation of the current state-of-the-art Earth-based VLBI data transport and processing instrumentation. The paper also briefly discusses approaches to the interferometric baseline state vector determination and synchronisation and heterodyning system. The technology-oriented sections of the paper do not aim at presenting a complete set of technological solutions for sub-millimeter (terahertz) space-borne interferometers. Rather, in combination with the original ESA Voyage 2050 White Paper, it sharpens the case for the next generation microarcsecond-level imaging instruments and provides starting points for further in-depth technology trade-off studies.
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| 7. |
- Jansen, Willemijn J, et al.
(författare)
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Prevalence Estimates of Amyloid Abnormality Across the Alzheimer Disease Clinical Spectrum.
- 2022
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Ingår i: JAMA neurology. - : American Medical Association (AMA). - 2168-6157 .- 2168-6149. ; 79:3, s. 228-243
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Tidskriftsartikel (refereegranskat)abstract
- One characteristic histopathological event in Alzheimer disease (AD) is cerebral amyloid aggregation, which can be detected by biomarkers in cerebrospinal fluid (CSF) and on positron emission tomography (PET) scans. Prevalence estimates of amyloid pathology are important for health care planning and clinical trial design.To estimate the prevalence of amyloid abnormality in persons with normal cognition, subjective cognitive decline, mild cognitive impairment, or clinical AD dementia and to examine the potential implications of cutoff methods, biomarker modality (CSF or PET), age, sex, APOE genotype, educational level, geographical region, and dementia severity for these estimates.This cross-sectional, individual-participant pooled study included participants from 85 Amyloid Biomarker Study cohorts. Data collection was performed from January 1, 2013, to December 31, 2020. Participants had normal cognition, subjective cognitive decline, mild cognitive impairment, or clinical AD dementia. Normal cognition and subjective cognitive decline were defined by normal scores on cognitive tests, with the presence of cognitive complaints defining subjective cognitive decline. Mild cognitive impairment and clinical AD dementia were diagnosed according to published criteria.Alzheimer disease biomarkers detected on PET or in CSF.Amyloid measurements were dichotomized as normal or abnormal using cohort-provided cutoffs for CSF or PET or by visual reading for PET. Adjusted data-driven cutoffs for abnormal amyloid were calculated using gaussian mixture modeling. Prevalence of amyloid abnormality was estimated according to age, sex, cognitive status, biomarker modality, APOE carrier status, educational level, geographical location, and dementia severity using generalized estimating equations.Among the 19097 participants (mean [SD] age, 69.1 [9.8] years; 10148 women [53.1%]) included, 10139 (53.1%) underwent an amyloid PET scan and 8958 (46.9%) had an amyloid CSF measurement. Using cohort-provided cutoffs, amyloid abnormality prevalences were similar to 2015 estimates for individuals without dementia and were similar across PET- and CSF-based estimates (24%; 95% CI, 21%-28%) in participants with normal cognition, 27% (95% CI, 21%-33%) in participants with subjective cognitive decline, and 51% (95% CI, 46%-56%) in participants with mild cognitive impairment, whereas for clinical AD dementia the estimates were higher for PET than CSF (87% vs 79%; mean difference, 8%; 95% CI, 0%-16%; P=.04). Gaussian mixture modeling-based cutoffs for amyloid measures on PET scans were similar to cohort-provided cutoffs and were not adjusted. Adjusted CSF cutoffs resulted in a 10% higher amyloid abnormality prevalence than PET-based estimates in persons with normal cognition (mean difference, 9%; 95% CI, 3%-15%; P=.004), subjective cognitive decline (9%; 95% CI, 3%-15%; P=.005), and mild cognitive impairment (10%; 95% CI, 3%-17%; P=.004), whereas the estimates were comparable in persons with clinical AD dementia (mean difference, 4%; 95% CI, -2% to 9%; P=.18).This study found that CSF-based estimates using adjusted data-driven cutoffs were up to 10% higher than PET-based estimates in people without dementia, whereas the results were similar among people with dementia. This finding suggests that preclinical and prodromal AD may be more prevalent than previously estimated, which has important implications for clinical trial recruitment strategies and health care planning policies.
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| 8. |
- Janssen, Pieter, et al.
(författare)
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A Novel Method for Study of Gastric Mechanical Functions in Conscious Mice
- 2009
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Ingår i: Digestive Diseases and Sciences. - : Springer Science and Business Media LLC. - 0163-2116 .- 1573-2568. ; 54:2, s. 222-231
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Tidskriftsartikel (refereegranskat)abstract
- A novel method has been developed for simultaneous study of gastric emptying, antral motility, and gastric muscle tone in conscious mice. Intragastric pressure was measured during infusion of an X-ray-opaque, viscous meal through a chronically implanted gastric fistula (0.25 ml/min). Compared with vehicle treatment, molsi-domine (nitric oxide donor) and atropine (muscarinic receptor antagonist) treatment significantly reduced the area under the intragastric pressure curve (AUC) by 37 +/- 4% and 35 +/- 3%, respectively, (mean +/- S.E.M.) whereas N-G-nitro-L-arginine methyl ester (L-NAME; nitric oxide synthase inhibitor) significantly increased the AUC by 20 +/- 3%. Atropine also significantly reduced the frequency and amplitude of stomach contraction-induced intragastric pressure waves while molsidomine only reduced the frequency. Gastric emptying, as assessed by X-ray imaging, was significantly delayed after L-NAME and atropine treatment. This methodology is the first to enable simultaneous assessment of gastric emptying, antral motility, and gastric tone in conscious mice and confirmed the important role of nitrergic and cholinergic innervation.
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| 9. |
- Janssen, Pieter, et al.
(författare)
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A novel method to assess gastric accommodation and peristaltic motility in conscious rats
- 2008
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Ingår i: Scandinavian Journal of Gastroenterology. - : Informa UK Limited. - 0036-5521 .- 1502-7708. ; 43:1, s. 34-43
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Tidskriftsartikel (refereegranskat)abstract
- Objective. To simultaneously study gastric accommodation and peristaltic motility in the whole stomach of conscious rats by measuring intragastric pressure (IGP) during test-meal infusion. Material and methods. After an overnight fast, a test-meal infusion system and a catheter to measure IGP were connected to a chronically implanted gastric fistula. IGP was measured during infusion of an X-ray-opaque, non-nutritious viscous test meal (0.25-2 ml min(-1)); gastric motility and emptying were assessed by X-ray fluoroscopy. Peristaltic motility-induced IGP waves were quantified as a motility index (wave amplitude divided by wavelength). Experiments were performed in Sprague-Dawley (SD) rats and in the high-anxiety Wistar Kyoto (WKY) rats. Moreover, the effects of 30 mg kg(-1) N-G-nitro-L-arginine methyl ester (L-NAME), 1 mg kg(-1) atropine or 20 mg kg(-1) molsidomine were tested in SD rats. Results. Compared with SD rats, IGP increased significantly faster during stomach distension in WKY rats, indicating impaired accommodation in the latter strain. Motility indices did not differ between the two strains. L-NAME significantly increased IGP during stomach distension, indicating decreased gastric accommodation. However, no change in motility indices was observed with L-NAME. Treatment with atropine significantly increased IGP and decreased motility indices, indicating decreased gastric accommodation and motility. Molsidomine significantly decreased IGP during stomach distension but did not affect motility. The results correspond to X-ray observations, and confirm literature data. Conclusions. We conclude that IGP measurement during test-meal infusion represents an efficient and novel method to compare gastric accommodation and peristaltic motility in the whole stomach of conscious rats.
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| 10. |
- Janssen, Pieter, et al.
(författare)
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Effect of Muscarinic and Nicotinic Receptor Antagonism on Rat Gastric Motor Activity
- 2010
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Ingår i: Pharmacology. - : S. Karger AG. - 0031-7012 .- 1423-0313. ; 85:5, s. 272-279
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Tidskriftsartikel (refereegranskat)abstract
- Background/Aims: Our aim was to investigate whether muscarinic and nicotinic receptors mediate nitric oxide release during motor events in the rat stomach. Methods: Isolated rat stomach volume changes were monitored in an organ bath setup with an intragastric balloon coupled to a barostat and studied in basal conditions and during electrical vagal stimulation (EVS). In conscious rats, the intragastric pressure (IGP) was measured during test meal infusion. Results: In the presence of N-G-nitro-L -arginine methyl ester (L-NAME; 0.1 mmol/l), EVS induced significant gastric contractions (mean +/- SEM = 0.27 +/- 0.04 ml; n = 6) that could be blocked by atropine (3 mu mol/l) and hexamethonium (0.1 mmol/l). In the presence of atropine and/or hexamethonium, EVS-induced relaxations could not be blocked by L-NAME, while exogenous nitric oxide could still relax the stomach. In conscious rats, atropine (1 mg kg(-1)) initially decreased IGP, while during further distension it increased IGP. In the presence of L -NAME (30 mg kg(-1)) atropine consistently decreased IGP.
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| 11. |
- van Cappellen, W., et al.
(författare)
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Apertif: Phased array feeds for the Westerbork Synthesis Radio Telescope: System overview and performance characteristics
- 2022
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 658
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Tidskriftsartikel (refereegranskat)abstract
- We describe the APERture Tile In Focus (Apertif) system, a phased array feed (PAF) upgrade of the Westerbork Synthesis Radio Telescope that transforms this telescope into a high-sensitivity, wide-field-of-view L-band imaging and transient survey instrument. Using novel PAF technology, up to 40 partially overlapping beams are formed on the sky simultaneously, significantly increasing the survey speed of the telescope. With this upgraded instrument, an imaging survey covering an area of 2300 deg2 is being performed that will deliver both continuum and spectral line datasets, of which the first data have been publicly released. In addition, a time domain transient and pulsar survey covering 15 000 deg2 is in progress. An overview of the Apertif science drivers, hardware, and software of the upgraded telescope is presented, along with its key performance characteristics.
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