527 research outputs found
Growth techniques used to develop CDS/CDTE thin film solar cells: a review
The method used to grow thin film CdS/CdTe solar cells has been described. Electronic material layers usually grow in three different modes; layer-by-layer growth mode, layer and cluster growth mode (Stransky-Krastanov) and cluster formation growth mode. Techniques such as molecular beam epitaxy (MBE), metal organic chemical vapour deposition (MOCVD) called melt growth or Bridgman are well known as high quality semiconductor growth techniques. One of the limitations of these techniques is the inability for manufacturing macro-electronic devices (~area 1m2) such as photovoltaic (PV) panels and large area display devices. To grow large area thin film (semiconductors), growth techniques such as close space sublimation (CSS), electrodeposition (ED), sputtering, spray pyrolysis etcetera have been tested and employed. This paper reviews in depth most of these techniques with more emphasis on the electrodeposition method because of it is simplicity and low cost.Keywords: Growth Techniques, CdS, CdTe, Thin Films, Solar Cells
Geographical trends in research: a preliminary analysis on authors' affiliations
In the last decade, research literature reached an enormous volume with an unprecedented current annual increase of 1.5 million new publications. As research gets ever more global and new countries and institutions, either from academia or corporate environment, start to contribute with their share, it is important to monitor this complex scenario and understand its dynamics.
We present a study on a conference proceedings dataset extracted from Springer Nature Scigraph that illustrates insightful geographical trends and highlights the unbalanced growth of competitive research institutions worldwide. Results emerged from our micro and macro analysis show that the distributions among countries of institutions and papers follow a power law, and thus very few countries keep producing most of the papers accepted by high-tier conferences. In addition, we found that the annual and overall turnover rate of the top 5, 10 and 25 countries is extremely low, suggesting a very static landscape in which new entries struggle to emerge. Finally, we highlight the presence of an increasing gap between the number of institutions initiating and overseeing research endeavours (i.e. first and last authors' affiliations) and the total number of institutions participating in research. As a consequence of our analysis, the paper also discusses our experience in working with affiliations: an utterly simple matter at first glance, that is instead revealed to be a complex research and technical challenge yet far from being solved
The Cryptococcus neoformans Titan cell is an inducible and regulated morphotype underlying pathogenesis.
Fungal cells change shape in response to environmental stimuli, and these morphogenic transitions drive pathogenesis and niche adaptation. For example, dimorphic fungi switch between yeast and hyphae in response to changing temperature. The basidiomycete Cryptococcus neoformans undergoes an unusual morphogenetic transition in the host lung from haploid yeast to large, highly polyploid cells termed Titan cells. Titan cells influence fungal interaction with host cells, including through increased drug resistance, altered cell size, and altered Pathogen Associated Molecular Pattern exposure. Despite the important role these cells play in pathogenesis, understanding the environmental stimuli that drive the morphological transition, and the molecular mechanisms underlying their unique biology, has been hampered by the lack of a reproducible in vitro induction system. Here we demonstrate reproducible in vitro Titan cell induction in response to environmental stimuli consistent with the host lung. In vitro Titan cells exhibit all the properties of in vivo generated Titan cells, the current gold standard, including altered capsule, cell wall, size, high mother cell ploidy, and aneuploid progeny. We identify the bacterial peptidoglycan subunit Muramyl Dipeptide as a serum compound associated with shift in cell size and ploidy, and demonstrate the capacity of bronchial lavage fluid and bacterial co-culture to induce Titanisation. Additionally, we demonstrate the capacity of our assay to identify established (cAMP/PKA) and previously undescribed (USV101) regulators of Titanisation in vitro. Finally, we investigate the Titanisation capacity of clinical isolates and their impact on disease outcome. Together, these findings provide new insight into the environmental stimuli and molecular mechanisms underlying the yeast-to-Titan transition and establish an essential in vitro model for the future characterization of this important morphotype
Mechanical shear stress and leukocyte phenotype and function: Implications for ventricular assist device development and use
Heart failure (HF) remains a disease of ever increasing prevalence in the modern world. Patients with end-stage HF are being referred increasingly for mechanical circulatory support (MCS). MCS can assist patients who are ineligible for transplant and stabilise eligible patients prior to transplantation. It is also used during cardiopulmonary bypass (CPB) surgery to maintain circulation whilst operating on the heart. Whilst MCS can stabilise HF and improve quality of life, complications such as infection and thrombosis remain a common risk. Leukocytes can contribute to both of these complications. Contact with foreign surfaces and the introduction of artificial mechanical shear stress can lead to activation of leukocytes, reduced functionality, and the release of pro-inflammatory and pro-thrombogenic microparticles. Assessing the impact of mechanical trauma to leukocytes is largely overlooked in comparison to red blood cells and platelets. This review provides an overview of the available literature on the effects of in vitro to clinical MCS systems on leukocyte phenotype and function. One purpose of this review is to emphasise the importance of studying mechanical trauma to leukocytes to better understand the occurrence of adverse events during MCS
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How predation and landscape fragmentation affect vole population dynamics
Background: Microtine species in Fennoscandia display a distinct north-south gradient from regular cycles to stable
populations. The gradient has often been attributed to changes in the interactions between microtines and their predators.
Although the spatial structure of the environment is known to influence predator-prey dynamics of a wide range of species,
it has scarcely been considered in relation to the Fennoscandian gradient. Furthermore, the length of microtine breeding
season also displays a north-south gradient. However, little consideration has been given to its role in shaping or generating
population cycles. Because these factors covary along the gradient it is difficult to distinguish their effects experimentally in
the field. The distinction is here attempted using realistic agent-based modelling.
Methodology/Principal Findings: By using a spatially explicit computer simulation model based on behavioural and
ecological data from the field vole (Microtus agrestis), we generated a number of repeated time series of vole densities
whose mean population size and amplitude were measured. Subsequently, these time series were subjected to statistical
autoregressive modelling, to investigate the effects on vole population dynamics of making predators more specialised, of
altering the breeding season, and increasing the level of habitat fragmentation. We found that fragmentation as well as the
presence of specialist predators are necessary for the occurrence of population cycles. Habitat fragmentation and predator
assembly jointly determined cycle length and amplitude. Length of vole breeding season had little impact on the
oscillations.
Significance: There is good agreement between our results and the experimental work from Fennoscandia, but our results
allow distinction of causation that is hard to unravel in field experiments. We hope our results will help understand the
reasons for cycle gradients observed in other areas. Our results clearly demonstrate the importance of landscape
fragmentation for population cycling and we recommend that the degree of fragmentation be more fully considered in
future analyses of vole dynamics
Quality of life endpoints in cancer cachexia clinical trials: Systematic review 3 of the cachexia endpoints series.
The use of patient-reported outcomes (PROMs) of quality of life (QOL) is common in cachexia trials. Patients' self-report on health, functioning, wellbeing, and perceptions of care, represent important measures of efficacy. This review describes the frequency, variety, and reporting of QOL endpoints used in cancer cachexia clinical trials. Electronic literature searches were performed in Medline, Embase, and Cochrane (1990-2023). Seven thousand four hundred thirty-five papers were retained for evaluation. Eligibility criteria included QOL as a study endpoint using validated measures, controlled design, adults (>18 years), ≥40 participants randomized, and intervention exceeding 2 weeks. The Covidence software was used for review procedures and data extractions. Four independent authors screened all records for consensus. Papers were screened by titles and abstracts, prior to full-text reading. PRISMA guidance for systematic reviews was followed. The protocol was prospectively registered via PROSPERO (CRD42022276710). Fifty papers focused on QOL. Twenty-four (48%) were double-blind randomized controlled trials. Sample sizes varied considerably (n = 42 to 469). Thirty-nine trials (78%) included multiple cancer types. Twenty-seven trials (54%) featured multimodal interventions with various drugs and dietary supplements, 11 (22%) used nutritional interventions alone and 12 (24%) used a single pharmacological intervention only. The median duration of the interventions was 12 weeks (4-96). The most frequent QOL measure was the EORTC QLQ-C30 (60%), followed by different FACIT questionnaires (34%). QOL was a primary, secondary, or exploratory endpoint in 15, 31 and 4 trials respectively, being the single primary in six. Statistically significant results on one or more QOL items favouring the intervention group were found in 18 trials. Eleven of these used a complete multidimensional measure. Adjustments for multiple testing when using multicomponent QOL measures were not reported. Nine trials (18%) defined a statistically or clinically significant difference for QOL, five with QOL as a primary outcome, and four with QOL as a secondary outcome. Correlation statistics with other study outcomes were rarely performed. PROMs including QOL are important endpoints in cachexia trials. We recommend using well-validated QOL measures, including cachexia-specific items such as weight history, appetite loss, and nutritional intake. Appropriate statistical methods with definitions of clinical significance, adjustment for multiple testing and few co-primary endpoints are encouraged, as is an understanding of how interventions may relate to changes in QOL endpoints. A strategic and scientific-based approach to PROM research in cachexia trials is warranted, to improve the research base in this field and avoid the use of QOL as supplementary measures
The reverse sural fasciocutaneous flap for the treatment of traumatic, infectious or diabetic foot and ankle wounds: A retrospective review of 16 patients
The authors present their experience with the use of sural fasciocutaneous flaps for the treatment of various soft tissue defects in the lower limb. This paper is a review of these flaps carried out between 2003 and 2008. The series consists of 16 patients, 11 men and 5 women with an average age of 41 years (17-81) and with a follow-up period between 2 and 7 years. The etiology was major velocity accident in six cases, diabetes mellitus with osteomyelitis after ORIF for fractures (2), work accident in five, and another two cases with complications of lower limb injuries. The defect areas were located on calcaneus, malleolar area, tarsal area and lower tibia. Associated risk factors in the patients for the flap performance were diabetes (five patients) and cigarette smoking (ten patients)
A Research Agenda for Helminth Diseases of Humans: Modelling for Control and Elimination
Mathematical modelling of helminth infections has the potential to inform policy and guide research for the control and elimination of human helminthiases. However, this potential, unlike in other parasitic and infectious diseases, has yet to be realised. To place contemporary efforts in a historical context, a summary of the development of mathematical models for helminthiases is presented. These efforts are discussed according to the role that models can play in furthering our understanding of parasite population biology and transmission dynamics, and the effect on such dynamics of control interventions, as well as in enabling estimation of directly unobservable parameters, exploration of transmission breakpoints, and investigation of evolutionary outcomes of control. The Disease Reference Group on Helminth Infections (DRG4), established in 2009 by the Special Programme for Research and Training in Tropical Diseases (TDR), was given the mandate to review helminthiases research and identify research priorities and gaps. A research and development agenda for helminthiasis modelling is proposed based on identified gaps that need to be addressed for models to become useful decision tools that can support research and control operations effectively. This agenda includes the use of models to estimate the impact of large-scale interventions on infection incidence; the design of sampling protocols for the monitoring and evaluation of integrated control programmes; the modelling of co-infections; the investigation of the dynamical relationship between infection and morbidity indicators; the improvement of analytical methods for the quantification of anthelmintic efficacy and resistance; the determination of programme endpoints; the linking of dynamical helminth models with helminth geostatistical mapping; and the investigation of the impact of climate change on human helminthiases. It is concluded that modelling should be embedded in helminth research, and in the planning, evaluation, and surveillance of interventions from the outset. Modellers should be essential members of interdisciplinary teams, propitiating a continuous dialogue with end users and stakeholders to reflect public health needs in the terrain, discuss the scope and limitations of models, and update biological assumptions and model outputs regularly. It is highlighted that to reach these goals, a collaborative framework must be developed for the collation, annotation, and sharing of databases from large-scale anthelmintic control programmes, and that helminth modellers should join efforts to tackle key questions in helminth epidemiology and control through the sharing of such databases, and by using diverse, yet complementary, modelling approaches
Ingraft chimerism in lung transplantation - a study in a porcine model of obliterative bronchiolitis
<p>Abstract</p> <p>Background</p> <p>Bronchial epithelium is a target of the alloimmune response in lung transplantation, and intact epithelium may protect allografts from rejection and obliterative bronchiolitis (OB). Herein we study the influence of chimerism on bronchial epithelium and OB development in pigs.</p> <p>Methods</p> <p>A total of 54 immunosuppressed and unimmunosuppressed bronchial allografts were serially obtained 2-90 days after transplantation. Histology (H&E) was assessed and the fluorescence in situ hybridization (FISH) method for Y chromosomes using pig-specific DNA-label was used to detect recipient derived cells in graft epithelium and bronchial wall, and donor cell migration to recipient organs. Ingraft chimerism was studied by using male recipients with female donors, whereas donor cell migration to recipient organs was studied using female recipients with male donors.</p> <p>Results</p> <p>Early appearance of recipient-derived cells in the airway epithelium appeared predictive of epithelial destruction (<it>R </it>= 0.610 - 0.671 and <it>p </it>< 0.05) and of obliteration of the bronchial lumen (<it>R </it>= 0.698 and <it>p </it>< 0.01). All allografts with preserved epithelium showed epithelial chimerism throughout the follow-up. Antirejection medication did not prevent, but delayed the appearance of Y chromosome positive cells in the epithelium (<it>p </it>< 0.05), or bronchial wall (<it>p </it>< 0.05).</p> <p>Conclusions</p> <p>In this study we demonstrate that early appearance of Y chromosomes in the airway epithelium predicts features characteristic of OB. Chimerism occurred in all allografts, including those without features of OB. Therefore we suggest that ingraft chimerism may be a mechanism involved in the repair of alloimmune-mediated tissue injury after transplantation.</p
Refugee and Migrant Women's Views of Antenatal Ultrasound on the Thai Burmese Border: A Mixed Methods Study
Antenatal ultrasound suits developing countries by virtue of its versatility, relatively low cost and safety, but little is known about women's or local provider's perspectives of this upcoming technology in such settings. This study was undertaken to better understand how routine obstetric ultrasound is experienced in a displaced Burmese population and identify barriers to its acceptance by local patients and providers.Qualitative (30 observations, 19 interviews, seven focus group discussions) and quantitative methods (questionnaire survey with 644 pregnant women) were used to provide a comprehensive understanding along four major themes: safety, emotions, information and communication, and unintended consequences of antenatal ultrasound in refugee and migrant clinics on the Thai Burmese border. One of the main concerns expressed by women was the danger of childbirth which they mainly attributed to fetal malposition. Both providers and patients recognized ultrasound as a technology improving the safety of pregnancy and delivery. A minority of patients experienced transitory shyness or anxiety before the ultrasound, but reported that these feelings could be ameliorated with improved patient information and staff communication. Unintended consequences of overuse and gender selective abortions in this population were not common.The results of this study are being used to improve local practice and allow development of explanatory materials for this population with low literacy. We strongly encourage facilities introducing new technology in resource poor settings to assess acceptability through similar inquiry
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