Combustion in thermonuclear supernova explosions

Type Ia supernovae are associated with thermonuclear explosions of white dwarf stars. Combustion processes convert material in nuclear reactions and release the energy required to explode the stars. At the same time, they produce the radioactive species that power radiation and give rise to the formation of the observables. Therefore, the physical mechanism of the combustion processes, as reviewed here, is the key to understand these astrophysical events. Theory establishes two distinct modes of propagation for combustion fronts: subsonic deflagrations and supersonic detonations. Both are assumed to play an important role in thermonuclear supernovae. The physical nature and theoretical models of deflagrations and detonations are discussed together with numerical implementations. A particular challenge arises due to the wide range of spatial scales involved in these phenomena. Neither the combustion waves nor their interaction with fluid flow and instabilities can be directly resolved in simulations. Substantial modeling effort is required to consistently capture such effects and the corresponding techniques are discussed in detail. They form the basis of modern multidimensional hydrodynamical simulations of thermonuclear supernova explosions. The problem of deflagration-to-detonation transitions in thermonuclear supernova explosions is briefly mentioned.Comment: Author version of chapter for 'Handbook of Supernovae,' edited by A. Alsabti and P. Murdin, Springer. 24 pages, 4 figure

Ripening stage and drying method affecting colour and quality attributes of Ziziphus mauritiana fruits in Zimbabwe

Ziziphus mauritiana Lamk. (Ber) fruit is harvested at different stages of ripening in the Zambezi valley of Zimbabwe. We hypothesize that the organoleptic quality attributes of fruits depend on post-harvestdrying method and ripening stage at harvest. This study was carried out to evaluate the effect of different stages of ripening on the quality of Z. mauritiana fruits during drying. The fruits were graded into green, yellowish-brown and brown categories and these formed the treatments. Some of these fruits were blanched before drying for 1, 2 and 3 weeks under the solar dryer and the open sun drying methods. The green fruits lost significantly (

Efficacy of the Best Possible Self protocol in diabetes self-management: A mixed-methods approach.

Recent research has demonstrated that positive affect may facilitate illness self-management. This study used a sequential exploratory mixed-methods typology to assess whether a brief writing task designed to boost positive affect (the Best Possible Self protocol) could improve aspects of diabetes self-management, specifically. A qualitative investigation explored people with diabetes' ( n = 20) views regarding Best Possible Self feasibility and acceptability, while a subsequent quantitative investigation assigned people with diabetes ( n = 50) to a Best Possible Self or non-Best Possible Self condition and assessed affect and self-management behaviours over a 4-week period. Findings indicated that individuals were receptive to the Best Possible Self and that it provided benefits for diabetes self-management

Challenges in management of Warfarin anti-coagulation in advanced HIV/AIDS patients with venous thrombotic events - A case series from a research clinic in rural Kericho, Kenya

Background: Venous thrombotic events (VTE) occur at high rates in HIV/AIDS patients and are likely under-diagnosed in rural sub-Saharan Africa.Objective: To describe clinical presentations and challenges in the management of VTE in patients with advanced HIV/AIDS.Design: Case series from patients enrolled in a prospective observational cohort study.Settings: A clinical research centre in rural Kericho, Kenya.Subjects: Two hundred patients with median age 38 (30-47) years, BMI 16.9 (12.4-20.3) kg/m2, haemoglobin 9.3 (6.8-13.4) g/dL, CD4+ T-cell count 27 (4-77) cells/mm3 and plasma HIV RNA 5.23 (3.70-5.88) log10copies/mL.Interventions: VTE cases were diagnosed by clinical presentation and Doppler/ radiographic confirmation.  Anti-coagulation therapy was managed by a multidisciplinary team; patients were initiated on enoxaparin or heparin followed by warfarin.Results: Over two years, 11 patients (5.5%) experienced VTE. All but one (10/11, 90.9%) case occurred within six months of starting ART. Nine patients had peripheral VTE (five popliteal, four femoral) and two had cerebral sinus thromboses. VTE was diagnosed 52 (1-469) days after ART initiation, and 81.8% of cases were outpatients at presentation. All patients received at least one concomitant medication that could significantly interact with warfarin (efavirenz, nevirapine, lopinavir/ritonavir, rifampicin, trimethoprim-sulfamethoxazole, and fluconazole). A median of 39 (10-180) days and eight (4-22) additional clinic visits were required to achieve/maintain a therapeutic INR of 2-3. Two minor bleeding complications occurred. No recurrent VTE cases were observed.Conclusion: Consideration of VTE and preparedness for management in patients with advanced HIV/AIDS starting ART is critical in sub-Saharan Africa. Overcoming challenges in anti-coagulation is possible in rural settings using a multidisciplinary team approach

Controlling a magnetic Feshbach resonance with laser light

The capability to tune the strength of the elastic interparticle interaction is crucial for many experiments with ultracold gases. Magnetic Feshbach resonances are a tool widely used for this purpose, but future experiments would benefit from additional flexibility such as spatial modulation of the interaction strength on short length scales. Optical Feshbach resonances offer this possibility in principle, but suffer from fast particle loss due to light-induced inelastic collisions. Here we show that light near-resonant with a molecular bound-to-bound transition can be used to shift the magnetic field at which a magnetic Feshbach resonance occurs. This makes it possible to tune the interaction strength with laser light and at the same time induce considerably less loss than an optical Feshbach resonance would do

Properties of wood composite plastics made from predominant Low Density Polyethylene (LDPE) plastics and their degradability in nature

To address concerns over plastics in the global environment, this project produced three wood plastics composites (WPCs) which could divert plastics from the waste stream into new materials. The three materials made had a ratio of 85%:15%, 90%:10%, and 95%:5% low density polyethylene (LDPE) to wood powder and were produced using the dissolution method. Physical and mechanical properties of each WPC were evaluated according to Japanese Industrial Standard (JIS) A 5908:2003. Their degradation in nature was evaluated through a graveyard test and assay test conducted in Coptotermes curvignathus termites. Results showed that density, moisture content, thickness swelling and water absorption of the WPCs fulfilled the JIS standard. The mechanical properties of these composites also met the JIS standard, particularly their modulus of elasticity (MOE). Modulus of rupture (MOR) and internal bonding (IB) showed in lower values, depending on the proportion of wood filler they contained. Discoloration of the WPCs was observed after burial in the soil with spectra alteration of attenuated transmission reflectance (ATR) in the band of 500–1000 cm-1 which could be assigned to detach the interphase between wood and plastics. As termite bait, the WPCs decreased in weight, even though the mass loss was comparatively small. Micro Confocal Raman Imaging Spectrometer revealed that termite guts from insects feeding on WPCs contained small amounts of LDPE. This indicated termite can consume plastics in the form of WPCs. Thus WPCs made predominantly of plastics can be degraded in nature. While producing WPCs can assist in decreasing plastics litter in the environment, the eventual fate of the LDPE in termites is still unknown

A grounded theory of type 2 diabetes prevention and risk perception

Objective Type 2 diabetes (T2D) prevention programmes should target high‐risk groups. Previous research has highlighted minimal engagement in such services from South Asian (SA) people. Given SA's elevated risk of T2D, there is a need to understand their perceptions, risks, and beliefs about T2D. Design This study aimed to assess T2D risk perception within a community sample of SA people using Grounded Theory methodology. Specifically, health beliefs were assessed, and we explored how these beliefs affected their T2D risk perceptions. Method Twenty SA participants (mean age = 38 years) without a diagnosis of T2D were recruited from community and religious settings across the North West of England. In line with grounded theory (Strauss & Corbin, 1990, Basics of qualitative research: Grounded theory procedures and techniques. Newbury Park: Sage Publications), data collection and analysis coincided. Results The superordinate category of Culturally Situated Risk Perception incorporated a complex psychological understanding of the formation of T2D risk perception, which takes into account the social, cultural, and community‐based environmental factors. This superordinate category was explained via two core categories (1) Diminished Responsibility, informed by sub‐categories of Destiny and Heredity, and (2) Influencing Healthy Lifestyle Behaviours, informed by sub‐categories of Socio‐cultural and Environmental. Conclusion This study investigated risk perception of T2D within the SA community. When considering health prevention in the context of an individual’s culture, we need to consider the social context in which they live. Failure to acknowledge the cultural‐situated T2D risk perception relevant to health promotion and illness messages may account for the issues identified with health care engagement in the SA population

Cultural Identity Conflict Informs Engagement with Self-Management Behaviours for South Asian Patients Living with Type-2 Diabetes: A Critical Interpretative Synthesis of Qualitative Research Studies

The prevalence of type-2 diabetes (T2D) is increasing, particularly among South Asian (SA) communities. Previous research has highlighted the heterogeneous nature of SA ethnicity and the need to consider culture in SA patients’ self-management of T2D. We conducted a critical interpretative synthesis (CIS) which aimed to a) develop a new and comprehensive insight into the psychology which underpins SA patients’ T2D self-management behaviours and b) present a conceptual model to inform future T2D interventions. A systematic search of the literature retrieved 19 articles, including 536 participants. These were reviewed using established CIS procedures. Analysis identified seven constructs, from which an overarching synthesizing argument ‘Cultural Conflict’ was derived. Our findings suggest that patients reconstruct knowledge to manage their psychological, behavioural, and cultural conflicts, impacting decisional conflicts associated with T2D self-management and health professional advice (un)consciously. Those unable to resolve this conflict were more likely to default towards cultural identity, continue to align with cultural preferences rather than health professional guidance, and reduce engagement with self-management. Our synthesis and supporting model promote novel ideas for self-management of T2D care for SA patients. Specifically, health professionals should be trained and supported to explore and mitigate negative health beliefs to enable patients to manage social-cultural influences that impact their self-management behaviours. Keywords: type 2 diabetes; South Asian; culture; conflict; healthcare; qualitative; evidence synthesi

Health professionals interface with cultural conflict in the delivery of type 2 diabetes care.

OBJECTIVE: This study explored the knowledge and experiences of health professionals (HPs) caring for South Asian patients with type 2 diabetes (T2D). DESIGN: Fourteen HPs, who supported patients with T2D, were interviewed. The recruitment strategy employed purposeful and theoretical sampling methods to recruit HPs who worked across primary and secondary care settings. MAIN OUTCOME MEASURES: Grounded Theory (GT) methodology and analysis generated a theoretical framework that explored HP's perceptions and experiences of providing diabetes care for South Asian patients. RESULTS: A GT, presenting a core category of Cultural Conflict in T2D care, explores the influences of HP's interactions and delivery of care for South Asian patients. This analysis is informed by four categories: (1) Patient Comparisons: South Asian vs White; (2) Recognising the Heterogeneous Nature of South Asian Patients; (3) Language and Communication; (4) HPs' Training and Experience. CONCLUSIONS: The findings consider how the role of social comparison, social norms, and diminished responsibility in patient self-management behaviours influence HPs' perceptions, implicit and explicit bias towards the delivery of care for South Asian patients. There was a clear call for further support and training to help HPs recognise the cultural-ethnic needs of their patients

Sub-luminous type Ia supernovae from the mergers of equal-mass white dwarfs with M~0.9 M_sun

Type Ia supernovae (SNe Ia) are thought to result from thermonuclear explosions of carbon-oxygen white dwarf stars. Existing models generally explain the observed properties, with the exception of the sub-luminous 1991-bg-like supernovae. It has long been suspected that the merger of two white dwarfs could give rise to a type Ia event, but hitherto simulations have failed to produce an explosion. Here we report a simulation of the merger of two equal-mass white dwarfs that leads to an underluminous explosion, though at the expense of requiring a single common-envelope phase, and component masses of ~0.9 M_sun. The light curve is too broad, but the synthesized spectra, red colour and low expansion velocities are all close to what is observed for sub-luminous 1991bg-like events. While mass ratios can be slightly less than one and still produce an underluminous event, the masses have to be in the range 0.83-0.9 M_sun.Comment: Accepted to Natur