273 research outputs found
Degradation mechanisms in organic photovoltaic devices
\u3cp\u3eIn the present review, the main degradation mechanisms occurring in the different layer stacking (i.e. photoactive layer, electrode, encapsulation film, interconnection) of polymeric organic solar cells and modules are discussed. Bulk and interfacial, as well as chemical and physical degradation mechanisms are reviewed, as well as their implications and external or internal triggers. Decay in I-V curves in function of time is usually due to the combined action of sequential and interrelated mechanisms taking place at different locations of the device, at specific kinetics. This often makes the identification of specific root causes of degradation challenging in non-model systems. Additionally, constant development and refinement in terms of type and combination of materials and processes render the ranking of degradation mechanisms as a function of their probability of occurrence and their detection challenging. However, it clearly appears that for the overall stability of organic photovoltaic devices, the actual photoactive layer, as well as the properties of the barrier and substrate (e.g. cut of moisture and oxygen ingress, mechanical integrity), remain critical. Interfacial stability is also crucial, as a modest degradation at the level of an interface can quickly and significantly influence the overall device properties.\u3c/p\u3
Effectiveness and cost-effectiveness of a nurse-delivered intervention to improve adherence to treatment for HIV : a pragmatic, multicentre, open-label, randomised clinical trial
This trial was funded from public money by the Netherlands Organisation for Health Research and Development (ZonMW; grant number 171002208). Aardex provided support on the development of the study website. We thank all the HIV nurses and physicians from the seven HIV clinics involved in the AIMS study for their input and collaboration (Academic Medical Centre, Slotervaart hospital, and St. Lucas-Andreas hospital, all in Amsterdam; the Leiden University Medical Centre, Leiden; HAGA hospital, The Hague; Erasmus Medical Centre, Rotterdam; and Isala clinic, Zwolle), the study participants, and the Stichting HIV Monitoring (SHM) for their support in accessing the SHM database for identifying patient inclusion criteria and developing the Markov model. Finally, we thank and remember Herman Schaalma (deceased) for his contribution to the study design and grant application.Peer reviewedPostprin
Obstacle detection display for visually impaired:Coding of direction, distance, and height on a vibrotactile waist band
Electronic travel aids (ETAs) can potentially increase the safety and comfort of blind users by detecting and displaying obstacles outside the range of the white cane. In a series of experiments, we aim to balance the amount of information displayed and the comprehensibility of the information taking into account the risk of information overload. In Experiment 1, we investigate perception of compound signals displayed on a tactile vest while walking. The results confirm that the threat of information overload is clear and present. Tactile coding parameters that are sufficiently discriminable in isolation may not be so in compound signals and while walking and using the white cane. Horizontal tactor location is a strong coding parameter, and temporal pattern is the preferred secondary coding parameter. Vertical location is also possible as coding parameter but it requires additional tactors and makes the display hardware more complex and expensive and less user friendly. In Experiment 2, we investigate how we can off-load the tactile modality by mitigating part of the information to an auditory display. Off-loading the tactile modality through auditory presentation is possible, but this off-loading is limited and may result in a new threat of auditory overload. In addition, taxing the auditory channel may in turn interfere with other auditory cues from the environment. In Experiment 3, we off-load the tactile sense by reducing the amount of displayed information using several filter rules. The resulting design was evaluated in Experiment 4 with visually impaired users. Although they acknowledge the potential of the display, the added of the ETA as a whole also depends on its sensor and object recognition capabilities. We recommend to use not more than two coding parameters in a tactile compound message and apply filter rules to reduce the amount of obstacles to be displayed in an obstacle avoidance ETA.</p
Modeled and Measured Operating Temperatures of Floating PV Modules: A Comparison
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Stochastic Improvement of Cyclic Railway Timetables
Real-time railway operations are subject to stochastic disturbances. However, a railway timetable is a deterministic plan. Thus a timetable should be designed in such a way that it can cope with the stochastic disturbances as well as possible. For that purpose, a timetable usually contains time supplements in several process times and buffer times between pairs of consecutive trains. This paper describes a Stochastic Optimization Model that can be used to allocate the time supplements and the buffer times in a given timetable in such a way that the timetable becomes maximally robust against stochastic disturbances. The Stochastic Optimization Model was tested on several instances of NS Reizigers, the main operator of passenger trains in the Netherlands. Moreover, a timetable that was computed by the model was operated in practice in a timetable experiment on the so-called “Zaanlijn”. The results show that the average delays of trains can often be reduced significantly by applying relatively small modifications to a given timetable
Temperature-Dependent Order-Disorder Phenomena in Crystal Structures Containing Dimers of Carboxylic Acids: The Crystal and Molecular Structure of 3,5-Dinitrobenzoic Acid at Room and Liquid Nitrogen Temperature and Statistics of the Geometries of Hydrogen-Bonded Carboxyl Groups
3,5-dinitrobenzoic acid crystallizes in space group P2i/c with four molecules in the unit cell. At room temperature (RT), the cell dimensions are a = 10.0237(4), b = 8.8728(3), c = 9.5090(4) A, = 95.68(1)° and V = 841.56(6) A3 and at liquid nitrogen temperature (LNT) a = 9.761(2), b = 8.9192(4), c = 9.444(2) A, /S = 97.55(1)° and V = 815.1(2) A3. At both temperatures, the crystals contain the common centrosymmetric carboxylic acid dimers. At RT the carboxyl groups are partially disordered, as indicated by the C=0 [1.249(3)] and C-0 [1.276(2)A] distances, C-C = 0 [118.4(2)1 and C-C-0 [116.4(2)°] angles and by the presence of disordered H atoms with occupancy factors of 0.63 and 0.37 in the O—O hydrogen bond.
At LNT, the acidic proton is ordered with a distance of 0.96(2) A from the donor hydroxyl O atom and the carboxyl group geometry is normal, with C=0 1.232(2) and C-0 1.305(2) A and C-C = 0 120.6(1) and C-C-O 114.4(1)°.
The differences Ar distances and A of the C-C-O angles are 0.027 A and 2.0°, respectively, at RT and 0.073 A and 6.2°, respectively, at LNT, which indicates an increase of ordering with decreasing temperature. The mechanism of disordering most probably invokes a temperature-dependent concerted two-proton jump across the dimer hydrogen bonds. To test the relationship between Ar and A, a statistical analysis is performed on the C-0 distances and C-C-O angles of RT and LNT dimer and non-dimer structures retrieved from the Cambridge Structural Database. The analysis indicates that disorder in RT dimers is more frequent than in RT non-dimers and also that ordering is pronounced in both LT dimer and non-dimer structures
Restricted effects of androgens on glucocorticoid signaling in the mouse prefrontal cortex and midbrain
Glucocorticoids are key executors of the physiological response to stress. Previous studies in mice showed that the androgen receptor (AR) influenced the transcriptional outcome of glucocorticoid treatment in white and brown adipocytes and in the liver. In the brain, we observed that chronic hypercorticism induced changes in gene expression that tended to be more pronounced in male mice. In the present study, we investigated if glucocorticoid signaling in the brain could be modulated by androgen. After chronic treatment with corticosterone, dihydrotestosterone, a combination of both, and corticosterone in combination with the AR antagonist enzalutamide, we compared the expression of glucocorticoid receptor (NR3C1, also abbreviated GR) target genes in brain regions where AR and GR are co-expressed, namely: prefrontal cortex, hypothalamus, hippocampus, ventral tegmental area and substantia nigra. We observed that androgen affected glucocorticoid signaling only in the prefrontal cortex and the substantia nigra. Dihydrotestosterone and corticosterone independently and inversely regulated expression of Sgk1 and Tsc22d3 in prefrontal cortex. AR antagonism with enzalutamide attenuated corticosterone-induced expression of Fkbp5 in the prefrontal cortex and of Fkbp5 and Sgk1 in the substantia nigra. Additionally, in the substantia nigra, AR antagonism increased expression of Th and Slc18a1, two genes coding for key components of the dopaminergic system. Our data indicate that androgen influence over glucocorticoid stimulation in the brain is not a dominant phenomenon in the context of high corticosterone levels, but can occur in the prefrontal cortex and substantia nigra
Conceptualizing and quantifying body condition using structural equation modelling:A user guide
Body condition is an important concept in behaviour, evolution and conservation, commonly used as a proxy of an individual's performance, for example in the assessment of environmental impacts. Although body condition potentially encompasses a wide range of health state dimensions (nutritional, immune or hormonal status), in practice most studies operationalize body condition using a single (univariate) measure, such as fat storage. One reason for excluding additional axes of variation may be that multivariate descriptors of body condition impose statistical and analytical challenges. Structural equation modelling (SEM) is used in many fields to study questions relating multidimensional concepts, and we here explain how SEM is a useful analytical tool to describe the multivariate nature of body condition. In this ‘Research Methods Guide’ paper, we show how SEM can be used to resolve different challenges in analysing the multivariate nature of body condition, such as (a) variable reduction and conceptualization, (b) specifying the relationship of condition to performance metrics, (c) comparing competing causal hypothesis and (d) including many pathways in a single model to avoid stepwise modelling approaches. We illustrated the use of SEM on a real-world case study and provided R-code of worked examples as a learning tool. We compared the predictive power of SEM with conventional statistical approaches that integrate multiple variables into one condition variable: multiple regression and principal component analyses. We show that model performance on our dataset is higher when using SEM and led to more accurate and precise estimates compared to conventional approaches. We encourage researchers to consider SEM as a flexible framework to describe the multivariate nature of body condition and thus understand how it affects biological processes, thereby improving the value of body condition proxies for predicting organismal performance. Finally, we highlight that it can be useful for other multidimensional ecological concepts as well, such as immunocompetence, oxidative stress and environmental conditions
Cost-effectiveness and Cost-utility of the Adherence Improving Self-management Strategy in Human Immunodeficiency Virus Care : A Trial-based Economic Evaluation
This study was funded by ZonMw (the Netherlands), program Doelmatigheidsonderzoek (grant number 171002208). This funding source had no role in study design, data collection, analysis, interpretation, or writing of the report. All authors declare that they have no competing interests. We thank the HIV-nurses and physicians from the seven HIV-clinics who were involved in the AIMSstudy (Academic Medical Center, Amsterdam; Slotervaart Hospital, Amsterdam; St. Lucas-Andreas Hospital, Amsterdam; the Leiden University Medical Center, Leiden; Haga Teaching Hospital, Den Haag; Erasmus Medical Center, Rotterdam; Isala Clinics, Zwolle) for their input and collaboration. We also would like to express our gratitude to the study participants. Written informed consent was obtained from each patient. The study has been approved by the ethics committee of each participating center.Peer reviewedPostprin
Treatment decision for transcatheter aortic valve implantation: the role of the heart team: Position statement paper of the Dutch Working Group of Transcatheter Heart Interventions
The current paper presents a position statement of the Dutch Working Group of Transcatheter Heart Valve Interventions that describes which patients with aortic stenosis should be considered for transcatheter aortic valve implantation and how this treatment proposal/decision should be made. Given the complexity of the disease and the assessment of its severity, in particular in combination with the continuous emergence of new clinical insights and evidence from physiological and randomised clinical studies plus the introduction of novel innovative treatment modalities, the gatekeeper of the treatment proposal/decision and, thus, of qualification for cost reimbursement is the heart team, which consists of dedicated professionals working in specialised centres
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