A thin rivulet or ridge subject to a uniform transverse shear stress at its free surface due to an external airflow

We use the lubrication approximation to analyse three closely related problems involving a thin rivulet or ridge (i.e. a two-dimensional droplet) of fluid subject to a prescribed uniform transverse shear stress at its free surface due to an external airflow, namely a rivulet draining under gravity down a vertical substrate, a rivulet driven by a longitudinal shear stress at its free surface, and a ridge on a horizontal substrate, and find qualitatively similar behaviour for all three problems. We show that, in agreement with previous numerical studies, the free surface profile of an equilibrium rivulet/ridge with pinned contact lines is skewed as the shear stress is increased from zero, and that there is a maximum value of the shear stress beyond which no solution with prescribed semi-width is possible. In practice, one or both of the contact lines will de-pin before this maximum value of the shear stress is reached, and so we consider situations in which the rivulet/ridge de-pins at one or both contact lines. In the case of de-pinning only at the advancing contact line, the rivulet/ridge is flattened and widened as the shear stress is increased from its critical value, and there is a second maximum value of the shear stress beyond which no solution with a prescribed advancing contact angle is possible. In contrast, in the case of de-pinning only at the receding contact line, the rivulet/ridge is thickened and narrowed as the shear stress is increased from its critical value, and there is a solution with a prescribed receding contact angle for all values of the shear stress. In general, in the case of de-pinning at both contact lines there is a critical “yield” value of the shear stress beyond which no equilibrium solution is possible and the rivulet/ridge will evolve unsteadily. In an Appendix we show that an equilibrium rivulet/ridge with prescribed flux/area is quasi-statically stable to two-dimensional perturbations

A thin rivulet or ridge subject to a uniform transverse\ud shear stress at its free surface due to an external airflow

We use the lubrication approximation to analyse three closely related problems involving a thin rivulet or ridge (i.e. a two-dimensional droplet) of fluid subject to a prescribed uniform transverse shear stress at its free surface due to an external airflow, namely a rivulet draining under gravity down a vertical substrate, a rivulet driven by a longitudinal shear stress at its free surface, and a ridge on a horizontal substrate, and find qualitatively similar behaviour for all three problems. We show that, in agreement with previous numerical studies, the free surface profile of an equilibrium rivulet/ridge with pinned contact lines is skewed as the shear stress is increased from zero, and that there is a maximum value of the shear stress beyond which no solution with prescribed semi-width is possible. In practice, one or both of the contact lines will de-pin before this maximum value of the shear stress is reached, and so we consider situations in which the rivulet/ridge de-pins at one or both contact lines. In the case of de-pinning only at the advancing contact line, the rivulet/ridge is flattened and widened as the shear stress is increased from its critical value, and there is a second maximum value of the shear stress beyond which no solution with a prescribed advancing contact angle is possible. In contrast, in the case of de-pinning only at the receding contact line, the rivulet/ridge is thickened and narrowed as the shear stress is increased from its critical value, and there is a solution with a prescribed receding contact angle for all values of the shear stress. In general, in the case of de-pinning at both contact lines there is a critical “yield” value of the shear stress beyond which no equilibrium solution is possible and the rivulet/ridge will evolve unsteadily. In an Appendix we show that an equilibrium rivulet/ridge with prescribed flux/area is quasi-statically stable to two-dimensional perturbations

Reconstructing ice-sheet accumulation rates at ridge B, East Antarctica

Understanding how ice sheets responded to past climate change is fundamental to forecasting how they will respond in the future. Numerical models calculating the evolution of ice sheets depend upon accumulation data, which are principally available from ice cores. Here, we calculate past rates of ice accumulation using internal layering. The englacial structure of the East Antarctic ice divide at ridge B is extracted from airborne ice-penetrating radar. The isochronous surfaces are dated at their intersection with the Vostok ice-core site, where the depth–age relationship is known. The dated isochrons are used as input to a one-dimensional ice-flow model to investigate the spatial accumulation distribution. The calculations show that ice-accumulation rates generally increase from Vostok lake towards ridge B. The western flank of the ice divide experiences markedly more accumulation than in the east. Further, ice accumulation increases northwards along the ice divide. The results also show the variability of accumulation in time and space around the ridge B ice divide over the last 124 000 years

The influence of MRI scan position on patients with oropharyngeal cancer undergoing radical radiotherapy

<p>Background: The purpose of this study was to demonstrate how magnetic resonance imaging (MRI) patient position protocols influence registration quality in patients with oropharyngeal cancer undergoing radical radiotherapy and the consequences for gross tumour volume (GTV) definition and radiotherapy planning.</p> <p>Methods and materials: Twenty-two oropharyngeal patients underwent a computed tomography (CT), a diagnostic MRI (MRID) and an MRI in the radiotherapy position within an immobilization mask (MRIRT). Clinicians delineated the GTV on the CT viewing the MRID separately (GTVC); on the CT registered to MRID (GTVD) and on the CT registered to MRIRT (GTVRT). Planning target volumes (PTVs) were denoted similarly. Registration quality was assessed by measuring disparity between structures in the three set-ups. Volumetric modulated arc therapy (VMAT) radiotherapy planning was performed for PTVC, PTVD and PTVRT. To determine the dose received by the reference PTVRT, we optimized for PTVC and PTVD while calculating the dose to PTVRT. Statistical significance was determined using the two-tailed Mann–Whitney or two-tailed paired student t-tests.</p> <p>Results: A significant improvement in registration accuracy was found between CT and MRIRT versus the MRID measuring distances from the centre of structures (geometric mean error of 2.2 mm versus 6.6 mm). The mean GTVC (44.1 cm3) was significantly larger than GTVD (33.7 cm3, p value = 0.027) or GTVRT (30.5 cm3, p value = 0.014). When optimizing the VMAT plans for PTVC and investigating the mean dose to PTVRT neither the dose to 99% (58.8%) nor 95% of the PTV (84.7%) were found to meet the required clinical dose constraints of 90% and 95% respectively. Similarly, when optimizing for PTVD the mean dose to PTVRT did not meet clinical dose constraints for 99% (14.9%) nor 95% of the PTV (66.2%). Only by optimizing for PTVRT were all clinical dose constraints achieved.</p> <p>Conclusions: When oropharyngeal patients MRI scans are performed in the radiotherapy position there are significant improvements in CT-MR image registration, target definition and PTV dose coverage.</p&gt

INTRODUCTION: A New Africa’s Media Image?

Africa’s Media Image in the 21st Century is the first book in over twenty years to examine the international media’s coverage of sub-Saharan Africa. It brings together leading researchers and prominent journalists to explore representation of the continent, and the production of that image, especially by international news media. The book highlights factors that have transformed the global media system, changing whose perspectives are told and the forms of media that empower new voices. This introductory chapter by the book editors assesses Africa’s changing media image, examines the new image-makers, and reviews the geopolitics impacting upon that image

What are the holistic care impacts among individuals living through the COVID-19 pandemic in residential or community care settings? An integrative systematic review.

The objective of this study was to critically synthesise evidence in relation to the holistic care impacts (physical, psychological, social, spiritual and environmental well-being) among individuals living in residential aged-care facilities (RACFs) with restrictions during the COVID-19 pandemic. An integrative systematic review followed a pre-registered protocol and has been reported according to the Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) Guidelines. Electronic databases were searched from inception to June 2022. Qualitative, quantitative and mixed methods studies were included. All articles were double-screened according to a pre-determined eligibility criterion. The review process was managed using Covidence systematic review software. Data from the studies were extracted, methodological quality appraisal conducted and a narrative synthesis conducted. 18 studies were included. The impact of restrictive practices and periods of lockdown impacted older people on all levels of individual quality-of-life. With or without COVID-19, residents experienced functional decline and many experienced malnutrition, increased incontinence, increased pain, and poorer general health and significant psychological distress. Depression increased with reduced social contact, as did anxiety and loneliness. Some residents spoke of suicidal ideation. It is highly plausible that further outbreaks may prompt knee-jerk reactions from public health departments and governing bodies to continue to restrict and lockdown facilities. Public health COVID-19 outbreak policy for aged care across the globe will need to consider the benefits verses risk debate, given the findings uncovered in this review. These findings showed that it is vital that policy considers quality-of-life domains - not solely survival rates

Current landscape of ecological momentary assessment (real-time data) methodology in cancer research: a systematic review.

To critically synthesize and describe the use and methods of ecological momentary assessment (EMA) in cancer research. A systematic review was conducted and has been reported according to the Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) Guideline. Electronic databases (APA PsycINFO, CINAHL, Cochrane Central Register of Controlled Trials, MEDLINE, Scopus, and Web of Science Core Collection) were searched using a variety of keywords and subject headings by an expert systematic review librarian. All publications were double screened by two reviewers using predetermined exclusion and inclusion criteria throughout the full review process. The review used Covidence Systematic Review Software. Methodological quality assessment and data extraction were performed. A narrative synthesis was conducted to examine the aim for EMA, the characteristics of the study samples, the EMA sampling procedures, EMA completion rates, outcome measures, and any implications of findings for survivorship care. A total of 42 EMA studies in cancer were included. Most studies used an electronic mobile device to capture EMA data apart from several that used paper diaries. Existing studies were found to have significant heterogeneity in methods and widely varying approaches to design and self-report measurements. While EMA in cancer research holds significant promise to advance cancer care research into the future by increasing ecological validity and reducing retrospective bias and can capture the unique idiographic within-person change over time, in real-time, further research is needed to develop standardized EMA self-report questionnaires. This is the first comprehensive systematic review to describe the use and methods of EMA in cancer research. There is significant heterogeneity in methods and widely varying approaches to design and self-report measurements in EMA cancer research. People affected by cancer found taking part in EMA studies reported benefit from the experience. However, researchers must engage with cancer survivors in the development and co-design of future EMA questionnaires to ensure relevant and acceptability of EMA data collection protocols

Scan-associated distress in people affected by cancer: a qualitative systematic review.

The term "scanxiety" has been coined to describe the anxiety commonly associated with individuals undergoing cancer-related imaging. Despite the prevalence and severity of scanxiety across various clinical and demographic populations, there remains a significant lack of qualitative insights from existing studies that effectively capture patients' experiences of scanxiety in their own words. Therefore, this review addresses the following research question: What are the experiences of scanxiety distress among people affected by cancer across the cancer care continuum? Following the PRISMA methodology, a meta-aggregation of qualitative studies was performed, encompassing patients of all age groups who had been diagnosed with cancer or were indicated for a cancer-related scan. Of the 556 articles screened, 15 were deemed eligible for inclusion in the analysis. The three overarching themes of 1) experience of "scan-itis," 2) experience of "patient-clinician support," and 3) development of self-management strategies reveal the complex and interconnected factors that influence scanxiety in individuals undergoing cancer-related imaging. These findings emphasized distress experienced by patients during the waiting period for scan results, the act of viewing the results, and even the delivery of "bad" news. Consequently, patients expressed a strong desire for increased information, communication, and empathy from attending healthcare providers. Patients also report a myriad of self-coping strategies to manage their scanxiety well before, during, and after their scan appointment. The study highlights the need for targeted interventions for those undergoing cancer-related scans, including increased awareness and education for health professionals regarding scanxiety

A geometric view of cryptographic equation solving

This paper considers the geometric properties of the Relinearisation algorithm and of the XL algorithm used in cryptology for equation solving. We give a formal description of each algorithm in terms of projective geometry, making particular use of the Veronese variety. We establish the fundamental geometrical connection between the two algorithms and show how both algorithms can be viewed as being equivalent to the problem of finding a matrix of low rank in the linear span of a collection of matrices, a problem sometimes known as the MinRank problem. Furthermore, we generalise the XL algorithm to a geometrically invariant algorithm, which we term the GeometricXL algorithm. The GeometricXL algorithm is a technique which can solve certain equation systems that are not easily soluble by the XL algorithm or by Groebner basis methods

A threat to biodiesel production from Palm oil by disease caused by the fungus Ganoderma

Oil palm (OP) is a major crop for the production of vegetable oil used in foods, cosmetics and increasingly biodiesel. There is an increasing awareness that crops are vulnerable to nefarious introduction of pathogenic microorganisms. Oil palms are prone to a rot by the fungus Ganoderma. White rot fungi are capable of degrading lignin. It is necessary to consider this mode of attack for effective control. Nevertheless, the existing literature is concerned with the (a) mode of spread and (b) molecular biology of Ganoderma. The high moisture content of coastal soil favour Ganoderma. High salinity and low soil pH appear to discourage the disease. The optimum current method of control is to rid fields of decayed OP. The optimal future approach may be to develop tolerant OP and altering lignin in OP may be possible. In conclusion, Ganoderma of OP is becoming increasingly virulent and control would benefit from consideration of the process as one of white rot.A palmeira é uma cultivar usada na produção de óleos alimentares vegetais, cosméticos e encontra-se em crescente aplicação na produção de biodiesel. Há aumento da consciência que as cultivares são vulneráveis à possível prática criminosa pela introdução intencional de microrganismos patogênicos nas lavouras. De um modo geral, as palmeiras são propensas à degradação quando atacada pelo fungo Ganoderma, conhecido como fungo da podridão branca, por degradar a lignina. É de grande importância considerar este tipo de podridão da palmeira quando atacada pelos microrganismos em questão, de modo a ser estabelecido um controle efetivo.No entanto, na literatura são encontrados trabalhos que ressaltam a importância: (a) de estar-se atento ao modo de proliferação desta praga e (b) de conhecer-se a biologia molecular do Ganoderma. A alta humidade presente no solo litorâneo favorece o surgimento do fungo Ganoderma. A alta salinidade e o baixo pH do solo surge como um ambiente desfavorável para a proliferação deste tipo de microrganismo. Atualmente, o melhor método de controle do Ganoderma é a extinção dos campos de palmeiras por ele contaminados. A melhor estratégia para o futuro estaria no desenvolvimento de palmeiras tolerantes ao ataque das referidas pragas, sendo uma possibilidade a alteração da lignina produzida nas palmeiras. Desta forma, conclui-se que o Ganoderma da palmeira está se tornando em um problema cada vez maior e o seu controle levaria à resolução de questões como a podridão branca