1,129 research outputs found
An extended classical solution of the droplet growth problem
Problems of applying the classical kinetic theory to the growth of small droplets from vapor are examined. A solution for the droplet growth equation is derived which is based on the assumption of a diffusive field extending to the drop surface. The method accounts for partial thermal and mass accommodation at the interface and the kinetic limit to the mass and heat fluxes, and it avoids introducing the artifact of a discontinuity in the thermal and vapor field near the droplet. Consideration of the environmental fields in spherical geometry utilizing directional fluxes yields boundary values in terms of known parameters and a new Laplace transform integral
Sustainable development and the rural-urban fringe : a review of the literature
Book: iii, 30 p., digital fileSustainable development is a concept which has captured the imagination of scholars,
practitioners, and politicians at all geographical scales. While Dykeman (1990a, p. 3) suggests that the sustainable development concept consists of "older, established ideas that are wrapped in new terminology," he does not suggest in even the slightest way that the concept should be withdrawn or ignored. Rather, Dykeman (1990b) used the concept as a central focus for an important international conference and a major publication. Recognition must be given to the fact that the sustainable development concept does offer fundamental contributions to an important framework, a framework which is still developing.
The essence of this paper is to examine the linkage and contradictions within and between the terms sustainable development and the rural-urban fringe. The literature reviewed is necessarily wide- ranging, however I will admit a personal bias towards perspectives from geography, environmental studies and agriculture. To present this review, a preliminary task is to set the context through a brief discussion of the principal terms, i.e. sustainable development and rural-urban fringe. The key document on sustainable development remains the report Our Common Future prepared by the World
Commission on Environment and Development (WCED) (1987), which must surely rate as one of the most cited documents of the late 1980s and early 1990s. Discussion of the rural-urban fringe will draw substantially on recent reviews and research documents (Beesley, 1991 a, b, 1993; Beesley and Bowles, 1993; Beesley and Macintosh, 1993; Bowles and Beesley, 1991; Macintosh and Beesley, 1993)
Failures of executive function when at a height:Negative height-related appraisals are associated with poor executive function during a virtual height stressor
It is difficult to maintain cognitive functioning in threatening contexts, even when it is imperative to do so. Research indicates that precarious situations can impair subsequent executive functioning, depending on whether they are appraised as threatening. Here, we used virtual reality to place participants at ground level or at a virtual height in order to examine the impact of a threat-related context on concurrent executive function and whether this relationship was modulated by negative appraisals of heights. Executive function was assessed via the Go/NoGo and N-Back tasks, indexing response inhibition and working memory updating respectively. Participants with negative appraisals of heights exhibited impaired executive function on both tasks when performing at a virtual height (i.e., a threat-related context) but not at ground-level, demonstrating the importance of considering the cognitive consequences of individual differences in negative interpretations of emotionally-evocative situations. We suggest that a virtual reality approach holds practical benefits for understanding how individuals are able to maintain cognitive ability when embedded within threatening situations
Empirical Validation of a New Data Product from the Interstellar Boundary Explorer Satellite
Since 2008, the Interstellar Boundary Explorer (IBEX) satellite has been
gathering data on heliospheric energetic neutral atoms (ENAs) while being
exposed to various sources of background noise, such as cosmic rays and solar
energetic particles. The IBEX mission initially released only a qualified
triple-coincidence (qABC) data product, which was designed to provide
observations of ENAs free of background contamination. Further measurements
revealed that the qABC data was in fact susceptible to contamination, having
relatively low ENA counts and high background rates. Recently, the mission team
considered releasing a certain qualified double-coincidence (qBC) data product,
which has roughly twice the detection rate of the qABC data product. This paper
presents a simulation-based validation of the new qBC data product against the
already-released qABC data product. The results show that the qBCs can
plausibly be said to share the same signal rate as the qABCs up to an average
absolute deviation of 3.6%. Visual diagnostics at an orbit, map, and full
mission level provide additional confirmation of signal rate coherence across
data products. These approaches are generalizable to other scenarios in which
one wishes to test whether multiple observations could plausibly be generated
by some underlying shared signal
Benefits of supportive strategies for carers of people with high-grade glioma: a systematic review: Strategies for addressing the needs of high-grade glioma carers
Purpose: To systematically review and examine current evidence for the carer-reported benefits of supportive care strategies for carers of adults with high-grade glioma (HGG). Methods: Four databases (CINAHL, EMBASE, PubMed, PsycINFO) were searched for articles published between January 2005 and April 2022 that assessed strategies for addressing the supportive care needs of carers of adults with HGG (WHO grade 3–4). Study selection and critical appraisal were conducted independently by three authors (DJ/MC, 2021; DJ/RJ 2022). Data extraction was conducted by one author (DJ) and checked by a second author (RJ). Results were synthesised narratively. Results: Twenty-one studies involving 1377 caregivers were included, targeting the carer directly (n = 10), the patient-carer dyad (n = 3), or focused on people with HGG + / − their carers (n = 8). A paucity of high-quality evidence exists for effective and comprehensive support directly addressing outcomes for carers of adults with HGG. Strategies that demonstrated some benefits included those that built carer knowledge or provided emotional support, delivered by health professionals or through peer support. Supportive and early palliative care programmes have potential to reduce unmet carer needs while providing ongoing carer support. Conclusion: Strategies incorporating an educational component, emotional support, and a regular needs assessment with corresponding tailored support are most valued by carers. Future practice development research should adopt a value-based approach and exceed evaluation of efficacy outcomes to incorporate evaluation of the experience of patients, carers, and staff, as well as costs
Validation of a mouse xenograft model system for gene expression analysis of human acute lymphoblastic leukaemia
<p>Abstract</p> <p>Background</p> <p>Pre-clinical models that effectively recapitulate human disease are critical for expanding our knowledge of cancer biology and drug resistance mechanisms. For haematological malignancies, the non-obese diabetic/severe combined immunodeficient (NOD/SCID) mouse is one of the most successful models to study paediatric acute lymphoblastic leukaemia (ALL). However, for this model to be effective for studying engraftment and therapy responses at the whole genome level, careful molecular characterisation is essential.</p> <p>Results</p> <p>Here, we sought to validate species-specific gene expression profiling in the high engraftment continuous ALL NOD/SCID xenograft. Using the human Affymetrix whole transcript platform we analysed transcriptional profiles from engrafted tissues without prior cell separation of mouse cells and found it to return highly reproducible profiles in xenografts from individual mice. The model was further tested with experimental mixtures of human and mouse cells, demonstrating that the presence of mouse cells does not significantly skew expression profiles when xenografts contain 90% or more human cells. In addition, we present a novel <it>in silico </it>and experimental masking approach to identify probes and transcript clusters susceptible to cross-species hybridisation.</p> <p>Conclusions</p> <p>We demonstrate species-specific transcriptional profiles can be obtained from xenografts when high levels of engraftment are achieved or with the application of transcript cluster masks. Importantly, this masking approach can be applied and adapted to other xenograft models where human tissue infiltration is lower. This model provides a powerful platform for identifying genes and pathways associated with ALL disease progression and response to therapy <it>in vivo</it>.</p
COVID-19 and vertical transmission: assessing the expression of ACE2 / TMPRSS2 in the human fetus and placenta to assess the risk of SARS-CoV-2 infection
Background: While pregnant women have been identified as a potentially at-risk group concerning COVID-19 infection, little is known regarding the susceptibility of the fetus to infection. Co-expression of ACE2 and TMPRSS2 has been identified as a pre-requisite for infection, and expression across different tissues is known to vary between children and adults. However, the expression of these proteins in the fetus is unknown. Methods: We performed a retrospective analysis of single cell data repositories. This data was then validated at both gene and protein level by performing qRT-PCR and two-colour immunohistochemistry on a library of second-trimester human fetal tissues. Findings: TMPRSS2 is present at both gene and protein level in the predominantly epithelial fetal tissues analysed. ACE2 is present at significant levels, only in the fetal intestine and kidney and is not expressed in the fetal lung. The placenta is also negative for the two proteins both during development and at term. Interpretation: This dataset indicates that the lungs are unlikely to be a viable route of SARS-CoV2 fetal infection. The fetal kidney, despite presenting both the proteins required for the infection, is anatomically protected from the exposure to the virus. However, the GI tract is likely to be susceptible to infection due to its high co-expression of both proteins, as well as its exposure to potentially infected amniotic fluid
Spatiotemporal competition and task-relevance shape the spatial distribution of emotional interference during rapid visual processing:Evidence from gaze-contingent eye-tracking
People’s ability to perceive rapidly presented targets can be disrupted both by voluntary encoding of a preceding target and by spontaneous attention to salient distractors. Distinctions between these sources of interference can be found when people search for a target in multiple rapid streams instead of a single stream: voluntary encoding of a preceding target often elicits subsequent perceptual lapses across the visual field, whereas spontaneous attention to emotionally salient distractors appears to elicit a spatially localized lapse, giving rise to a theoretical account suggesting that emotional distractors and subsequent targets compete spatiotemporally during rapid serial visual processing. We used gaze-contingent eye-tracking to probe the roles of spatiotemporal competition and memory encoding on the spatial distribution of interference caused by emotional distractors, while also ruling out the role of eye-gaze in driving differences in spatial distribution. Spontaneous target perception impairments caused by emotional distractors were localized to the distractor location regardless of where participants fixated. But when emotional distractors were task-relevant, perceptual lapses occurred across both streams while remaining strongest at the distractor location. These results suggest that spatiotemporal competition and memory encoding reflect a dual-route impact of emotional stimuli on target perception during rapid visual processing
Mucopolysaccharidosis type IIIB may predominantly present with an attenuated clinical phenotype
Mucopolysaccharidosis type IIIB (MPS IIIB, Sanfilippo syndrome type B) is a lysosomal storage disorder caused by deficiency of the enzyme N-acetyl-α-D-glucosaminidase (NAGLU). Information on the natural course of MPS IIIB is scarce but much needed in view of emerging therapies. To improve knowledge on the natural course, data on all 52 MPS IIIB patients ever identified by enzymatic studies in the Netherlands were gathered. Clinical data on 44 patients could be retrieved. Only a small number (n = 9; 21%) presented with a classical MPS III phenotype; all other patients showed a much more attenuated course of the disease characterized by a significantly slower regression of intellectual and motor abilities. The majority of patients lived well into adulthood. First signs of the disease, usually mild developmental delay, were observed at a median age of 4 years. Subsequently, patients showed a slowing and eventually a stagnation of development. Patients with the attenuated phenotype had a stable intellectual disability for many years. Molecular analysis was performed in 24 index patients. The missense changes p.R643C, p.S612G, p.E634K, and p.L497V were exclusively found in patients with the attenuated phenotype. MPS IIIB comprises a remarkably wide spectrum of disease severity, and an unselected cohort including all Dutch patients showed a large proportion (79%) with an attenuated phenotype. MPS IIIB must be considered in patients with a developmental delay, even in the absence of a progressive decline in intellectual abilities. A key feature, necessitating metabolic studies, is the coexistence of behavioral problems
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