PROBING QUANTUM TRANSPORT IN THREE-TERMINAL NANOJUNCTIONS

One-dimensional (1D) nanoscale systems—structures with the lateral dimensions ranging from 1 nm to 100 nm — have received significant research interest due to their unique structure-guided properties that promise functionalities far more superior than their bulk counterparts. The quantum confinement effect in 1D nanostructures provides us with a very powerful tool to tune their electrical, magnetic, optical and thermal properties and opens the gateway for their multifunctional usages in next-generation electronics. In particular, carbon nanotubes and semiconductor nanowires are found to offer tremendous opportunities to form the junction devices with controlled electronic and optoelectronic properties crucial to predictable device functions. Along with the experimental progress in synthesis and fabrication techniques leading to nano-dimensional devices with diverse applications, theoretical insights at the level of electronic structure is equally important to tune various material properties for achieving greater device performance coupled with a wider range of functionalities. This thesis provides a theoretical description of the quantum transport properties in semiconductor core-shell nanowire field effect transistors (FETs) and (8,0) single-wall carbon nanotube contacted to ferromagnetic electrodes using the first principles density functional theory (DFT) in conjunction with the coherent single-particle many-body Green’s functions approach. The first project of the thesis outlines the superior performance of a semiconductor Si-Ge core-shell nanowire quantum dot FET over its pristine Si nanowire counterpart. In this work, we have unlocked the switching mechanism responsible for the superior performance of the Si-Ge nanowire FET with the pz-orbitals in the (outer)shell-layer providing the carrier pathway in both nanowire FETs. This is followed by a work on charge transport in semiconductor Ge-Si core-shell nanowire quantum dot FETs of two different Ge-core diameters. Here, we have identified the most probable tunneling pathway of electrons in Ge-Si FETs with an orbital spatial level resolution which demonstrates the gate-bias-driven decoupling of carrier transport between the core and shell-region. Our calculations hold a qualitative agreement with the experimentally reported results. Irrespective of the Ge core diameter, we observed excellent FET characteristics within a certain threshold gate bias after which the drain current is found to drop rapidly leading to the negative differential resistance (NDR). An orbital level analysis reveals a strong coupling between the pz-orbitals of the core-Ge and the s-orbitals of the gold electrode giving rise to the peak state of NDR; no such coupling is found at the valley NDR state for which the contribution comes solely from the pz-orbitals of the shell-Si. The final project of this thesis comprises the result of our work on spin transport in an (8,0) singlewall carbon nanotube - nickel magnetic tunnel junction. We found an oscillatory tunnel magnetoresistance showing a wide variation in its amplitude and width with the gate bias coupled with TMR sign reversals as observed in the experiment. Analysis of our calculation revealed a nonlinear coupling at the interface with s- and d-orbitals of different Ni atoms hybridized with pz orbitals of different interfacial carbon atoms at each gate bias points. Inserting an oxide layer at the interface is found to tune the oscillation in TMR in a predictable manner resulting in a much smoother oscillation critical to its application

Satisfaction and adherence of patients with amputations to physiotherapy service at public hospitals in KwaZulu-Natal, South Africa

Background: Individuals who have undergone a lower limb amputation require comprehensive rehabilitation from the multidisciplinary team to ensure optimal treatment outcomes and social integration. Physiotherapists play a pivotal role within the multidisciplinary team and offer patients physical and psychosocial rehabilitative care. Determining patients’ satisfaction levels and exploring factors affecting adherence to physiotherapy interventions can inform practice and improve service delivery of rehabilitation within resource poor settings such as South Africa.Objectives: To determine the level of satisfaction with physiotherapy services rendered to acute and sub-acute in-patients with lower limb amputations and to explore factors affecting adherence to physiotherapy intervention.Methods: A prospective survey of 35 patients with lower limb amputations from four public hospitals in South Africa was undertaken. A modified version of the Hampstead rehabilitation centre patient satisfaction questionnaire was utilised.Results: Majority of participants were satisfied with the physiotherapy services whilst a few reported dissatisfaction. Three themes emerged whilst exploring the patients’ experience relating to adherence to physiotherapy programmes. Themes included service delivery, patient-therapist interaction and participation barriers and facilitators.Conclusion: Recommendations aimed to improve quality of care and healthcare outcomes thereby enhancing the participants’ adherence to the physiotherapy programme.Keywords: amputation, patient satisfaction, patient adherence, physiotherapy

Impact of Air Pollution on Global Burden of Disease in 2019

Air pollution consisting of ambient air pollution and household air pollution (HAP) threatens health globally. Air pollution aggravates the health of vulnerable people such as infants, children, women, and the elderly as well as people with chronic diseases such as cardiorespiratory illnesses, little social support, and poor access to medical services. This study is aimed to estimate the impact of air pollution on global burden of disease (GBD). We extracted data about mortality and disability adjusted life years (DALYs) attributable to air pollution from 1990 to 2019. The extracted data were then organized and edited into a usable format using STATA version 15. Furthermore, we also estimated the impacts for three categories based on their socio-demographic index (SDI) as calculated by GBD study. The impacts of air pollution on overall burden of disease by SDI, gender, type of pollution, and type of disease is estimated and their trends over the period of 1990 to 2019 are presented. The attributable burden of ambient air pollution is increasing over the years while attributable burden of HAP is declining over the years, globally. The findings of this study will be useful for evidence-based planning for prevention and control of air pollution and reduction of burden of disease from air pollution at global, regional, and national levels

Hypertension screening, awareness, treatment, and control: a study of their prevalence and associated factors in a nationally representative sample from Nepal

Background: The growing burden of hypertension is emerging as one of the major healthcare challenges in low- and middle-income countries (LMICs), such as Nepal. Given that they are struggling to deliver adequate health services, some LMICs have significant gaps in the cascade of hypertension care (including screening, awareness, treatment, and control). This results in uncontrolled hypertension, placing a high burden on both patients and healthcare providers. Objective: The objective of this study was to quantify the gaps in hypertension screening, awareness, treatment, and control in the Nepalese population. Methods: We used the data from a pooled sample of 9682 participants collected through two consecutive STEPwise approach to Surveillance (STEPS) surveys conducted in Nepal in 2013 and 2019. A multistage cluster sampling method was applied in the surveys, to select nationally representative samples of 15- to 69-year-old Nepalese individuals. Prevalence ratios were calculated using multivariable Poisson regression. Results: Among the hypertensive participants, the prevalence of hypertension screening was 65.9% (95% CI: 62.2, 69.5), the prevalence of hypertension awareness was 20% (95% CI: 18.1, 22.1), the prevalence of hypertension treatment was 10.3% (95% CI: 8.8, 12.0), and the prevalence of hypertension control was 3.8% (95% CI: 2.9, 4.9). The unmet need of hypertension treatment and control was highest amongst the poorest individuals, the participants from Lumbini and Sudurpaschim provinces, those who received treatment in public hospitals, the uninsured, and those under the age of 30 years. Conclusions: The gaps in the cascade of hypertension care in Nepal are large. These gaps are particularly pronounced among the poor, persons living in Lumbini and Sudurpaschim provinces, those who sought treatment in public hospitals, those who did not have health insurance, and young people. National- and local-level public health interventions are needed to improve hypertension screening, awareness, treatment, and control in Nepal

Barriers and facilitators to the implementation of a national multisectoral action plan for the prevention and control of noncommunicable diseases in Nepal:perspectives of stakeholders

BACKGROUND: Nepal adopted the Multisectoral Action Plan for the Prevention and Control of Non-Communicable Diseases (MSAP) in 2014. Implementation of the plan has been challenging, with limited participation from non-health sectors. OBJECTIVES: The overall aim of the study was to gain the perspectives of key stakeholders involved in the Nepal MSAP on the barriers and facilitators to its implementation, through the participation of relevant sectors in the plan. METHODS: We held face-to-face semi-structured interviews with 12 stakeholders working in sectors involved in the MSAP. These sectors included the Office of the Prime Minister and Council of Ministries; Ministry of Health and Population (MOHP); Ministry of Education, Science and Technology; Ministry of Forest and Environment; academia; and professional organizations. Thematic analysis of transcripts was used to identify themes on awareness of NCDs, awareness of the MSAP, and barriers and facilitators to participation in the MSAP. RESULTS: Participants recognised NCDs as a growing and major burden in Nepal. However, a number of participants were not familiar with the MSAP, identifying a lack of leadership and poor dissemination. Political and systemic transformation, since the adoption of the MSAP, was seen as a key barrier to implementation. International commitments to develop multisectoral action made by the Government of Nepal were identified as drivers. The recent establishment of a separate section for NCDs and Mental Health within the Department of Health Services of MOHP and the promotion of a Health in All Policies (HiAP) approach in recent national documents, were both considered to support implementation. CONCLUSIONS: The establishment of permanent multisectoral or multistakeholder mechanisms has been challenging despite strong political calls for their development. Moving beyond 2020, multisectoral action plans should engage with stakeholders from federal, provincial and local governments in order to develop costed action plans with specific roles and responsibilities for each sector

Mitigating losses: how scientific organisations can help address the impact of the COVID-19 pandemic on early-career researchers.

Scientific collaborations among nations to address common problems and to build international partnerships as part of science diplomacy is a well-established notion. The international flow of people and ideas has played an important role in the advancement of the 'Sciences' and the current pandemic scenario has drawn attention towards the genuine need for a stronger role of science diplomacy, science advice and science communication. In dealing with the COVID-19 pandemic, visible interactions across science, policy, science communication to the public and diplomacy worldwide have promptly emerged. These interactions have benefited primarily the disciplines of knowledge that are directly informing the pandemic response, while other scientific fields have been relegated. The effects of the COVID-19 pandemic on scientists of all disciplines and from all world regions are discussed here, with a focus on early-career researchers (ECRs), as a vulnerable population in the research system. Young academies and ECR-driven organisations could suggest ECR-powered solutions and actions that could have the potential to mitigate these effects on ECRs working on disciplines not related to the pandemic response. In relation with governments and other scientific organisations, they can have an impact on strengthening and creating fairer scientific systems for ECRs at the national, regional, and global level

A collaboratively derived international research agenda on legislative science advice

The quantity and complexity of scientific and technological information provided to policymakers have been on the rise for decades. Yet little is known about how to provide science advice to legislatures, even though scientific information is widely acknowledged as valuable for decision-making in many policy domains. We asked academics, science advisers, and policymakers from both developed and developing nations to identify, review and refine, and then rank the most pressing research questions on legislative science advice (LSA). Experts generally agree that the state of evidence is poor, especially regarding developing and lower-middle income countries. Many fundamental questions about science advice processes remain unanswered and are of great interest: whether legislative use of scientific evidence improves the implementation and outcome of social programs and policies; under what conditions legislators and staff seek out scientific information or use what is presented to them; and how different communication channels affect informational trust and use. Environment and health are the highest priority policy domains for the field. The context-specific nature of many of the submitted questions—whether to policy issues, institutions, or locations—suggests one of the significant challenges is aggregating generalizable evidence on LSA practices. Understanding these research needs represents a first step in advancing a global agenda for LSA research.Fil: Akerlof, Karen. George Mason University; Estados UnidosFil: Tyler, Chris. University College London;Fil: Foxen, Sarah Elizabeth. University College London;Fil: Heath, Erin. American Association for the Advancement of Science; Estados UnidosFil: Gual Soler, Marga. American Association for the Advancement of Science; Estados UnidosFil: Allegra, Alessandro. University College London;Fil: Cloyd, Emily T.. American Association for the Advancement of Science; Estados UnidosFil: Hird, John A.. University of Massachussets; Estados UnidosFil: Nelson, Selena M.. George Mason University; Estados UnidosFil: Nguyen, Christina T.. George Mason University; Estados UnidosFil: Gonnella, Cameryn J.. Herndon; Estados UnidosFil: Berigan, Liam A.. Kansas State University; Estados UnidosFil: Abeledo, Carlos R.. Universidad de Buenos Aires; ArgentinaFil: Al Yakoub, Tamara Adel. Yarmouk University; JordaniaFil: Andoh, Harris Francis. Tshwane University Of Technology; Sudáfrica. Tshwane University of Technology; GhanaFil: dos Santos Boeira, Laura. Veredas Institute; BrasilFil: van Boheemen, Pieter. Rathenau Instituut; Países BajosFil: Cairney, Paul. University of Stirling; Reino UnidoFil: Cook Deegan, Robert. Arizona State University; Estados UnidosFil: Costigan, Gavin. Foundation For Science And Technology; Reino UnidoFil: Dhimal, Meghnath. Nepal Health Research Council; NepalFil: Di Marco, Martín Hernán. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Sociales. Instituto de Investigaciones "Gino Germani"; ArgentinaFil: Dube, Donatus. National University of Science and Technology; Zimbabu

Global, regional, and national prevalence and mortality burden of sickle cell disease, 2000–2021: a systematic analysis from the Global Burden of Disease Study 2021

Background Previous global analyses, with known underdiagnosis and single cause per death attribution systems, provide only a small insight into the suspected high population health effect of sickle cell disease. Completed as part of the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2021, this study delivers a comprehensive global assessment of prevalence of sickle cell disease and mortality burden by age and sex for 204 countries and territories from 2000 to 2021. Methods We estimated cause-specific sickle cell disease mortality using standardised GBD approaches, in which each death is assigned to a single underlying cause, to estimate mortality rates from the International Classification of Diseases (ICD)-coded vital registration, surveillance, and verbal autopsy data. In parallel, our goal was to estimate a more accurate account of sickle cell disease health burden using four types of epidemiological data on sickle cell disease: birth incidence, age-specific prevalence, with-condition mortality (total deaths), and excess mortality (excess deaths). Systematic reviews, supplemented with ICD-coded hospital discharge and insurance claims data, informed this modelling approach. We employed DisMod-MR 2.1 to triangulate between these measures—borrowing strength from predictive covariates and across age, time, and geography—and generated internally consistent estimates of incidence, prevalence, and mortality for three distinct genotypes of sickle cell disease: homozygous sickle cell disease and severe sickle cell β-thalassaemia, sickle-haemoglobin C disease, and mild sickle cell β-thalassaemia. Summing the three models yielded final estimates of incidence at birth, prevalence by age and sex, and total sickle cell disease mortality, the latter of which was compared directly against cause-specific mortality estimates to evaluate differences in mortality burden assessment and implications for the Sustainable Development Goals (SDGs). Findings Between 2000 and 2021, national incidence rates of sickle cell disease were relatively stable, but total births of babies with sickle cell disease increased globally by 13·7% (95% uncertainty interval 11·1–16·5), to 515 000 (425 000–614 000), primarily due to population growth in the Caribbean and western and central sub-Saharan Africa. The number of people living with sickle cell disease globally increased by 41·4% (38·3–44·9), from 5·46 million (4·62–6·45) in 2000 to 7·74 million (6·51–9·2) in 2021. We estimated 34 400 (25 000–45 200) cause-specific all-age deaths globally in 2021, but total sickle cell disease mortality burden was nearly 11-times higher at 376 000 (303 000–467 000). In children younger than 5 years, there were 81 100 (58 800–108 000) deaths, ranking total sickle cell disease mortality as 12th (compared to 40th for cause-specific sickle cell disease mortality) across all causes estimated by the GBD in 2021. Interpretation Our findings show a strikingly high contribution of sickle cell disease to all-cause mortality that is not apparent when each death is assigned to only a single cause. Sickle cell disease mortality burden is highest in children, especially in countries with the greatest under-5 mortality rates. Without comprehensive strategies to address morbidity and mortality associated with sickle cell disease, attainment of SDG 3.1, 3.2, and 3.4 is uncertain. Widespread data gaps and correspondingly high uncertainty in the estimates highlight the urgent need for routine and sustained surveillance efforts, further research to assess the contribution of conditions associated with sickle cell disease, and widespread deployment of evidence-based prevention and treatment for those with sickle cell disease.publishedVersio