In situ TEM modification of individual silicon nanowires and their charge transport mechanisms.

Correlating the structure and composition of nanowires grown by the vapour-liquid-solid (VLS) mechanism with their electrical properties is essential for designing nanowire devices. In situ transmission electron microscopy (TEM) that can image while simultaneously measuring the current-voltage (I-V) characteristics of individual isolated nanowires is a unique tool for linking changes in structure with electronic transport. Here we grow and electrically connect silicon nanowires inside a TEM to perform in situ electrical measurements on individual nanowires both at high temperature and upon surface oxidation, as well as under ambient conditions. As-grown, the oxide-free nanowires have nonlinear I-V characteristics. We analyse the I-V measurements in terms of both bulk and injection limited transport models, finding Joule heating effects, bulk-limiting effects for thin nanowires and an injection-limiting effect for thick wires when high voltages are applied. When the nanowire surface is modified by in situ oxidation, drastic changes occur in the electronic properties. We investigate the relation between the observed geometry, changes in the surface structure and changes in electronic transport, obtaining information for individual nanowires that is inaccessible to other measuring techniques.

A Systematic Review of Outcome Measures Employed in Aneurysmal Subarachnoid Hemorrhage (aSAH) Clinical Research.

Consensus on appropriate outcome measures to use in aneurysmal subarachnoid hemorrhage (aSAH) research has not been established, although the transition toward a core outcome set (COS) would provide significant benefits. To inform COS development, we conducted a systematic review to identify outcome measures included in reports of randomized clinical trials (RCTs) of interventions in patients with aSAH. Ovid Medline, EMBASE, CINAHL, and CENTRAL were searched. RCTs investigating aSAH published between January 1996 and May 2015 were included. The primary and secondary outcomes of RCTs were recorded and classified according to the OMERACT Consortium's framework. We identified 1093 potential studies of which 129 met inclusion criteria representing 24 238 patients. There were 285 unique outcome measures. The Glasgow Outcome Scale (GOS) was the most frequently used primary outcome (13/129, 10.1%). Mortality was reported in 84 trials (65.1%) with 3 months the most common time point (34/129, 26.4%). The GOS (65/129, 50.4%) and the Modified Rankin Scale (51/129, 39.5%) were the most commonly reported functional measures; however, these were reported at different time points and often dichotomized using different ranges. Patient-reported quality of life measures were used in 11 trials (8.5%). Transcranial Doppler was the most frequently used imaging modality (40/129, 31.0%). Definitions and reporting of vasospasm, delayed cerebral ischemia and imaging modality results were highly variable. The marked heterogeneity of outcomes in reports of RCTs supports the development of a core outcome set for aSAH trials. Our study has identified a wide range of outcomes for potential inclusion in a future aSAH COS.

Defining the correlates of lymphopenia and independent predictors of poor clinical outcome in adults hospitalized with COVID-19 in Australia.

Lymphopenia is a common feature of acute COVID-19 and is associated with increased disease severity and 30-day mortality. Here we aim to define the demographic and clinical characteristics that correlate with lymphopenia in COVID-19 and determine if lymphopenia is an independent predictor of poor clinical outcome. We analysed the ENTER-COVID (Epidemiology of hospitalized in-patient admissions following planned introduction of Epidemic SARS-CoV-2 to highly vaccinated COVID-19 naïve population) dataset of adults (N = 811) admitted for COVID-19 treatment in South Australia in a retrospective registry study, categorizing them as (a) lymphopenic (lymphocyte count < 1 × 109/L) or (b) non-lymphopenic at hospital admission. Comorbidities and laboratory parameters were compared between groups. Multiple regression analysis was performed using a linear or logistic model. Intensive care unit (ICU) patients and non-survivors exhibited lower median lymphocyte counts than non-ICU patients and survivors respectively. Univariate analysis revealed that low lymphocyte counts associated with hypertension and correlated with haemoglobin, platelet count and negatively correlated with urea, creatinine, bilirubin, and aspartate aminotransferase (AST). Multivariate analysis identified age, male, haemoglobin, platelet count, diabetes, creatinine, bilirubin, alanine transaminase, c-reactive protein (CRP) and lactate dehydrogenase (LDH) as independent predictors of poor clinical outcome in COVID-19, while lymphopenia did not emerge as a significant predictor.

Clinical and laboratory features of COVID-19 illness and outcomes in immunocompromised individuals during the first pandemic wave in Sydney, Australia.

People with immunocompromising conditions are at increased risk of SARS-CoV-2 infection and mortality, however early in the pandemic it was challenging to collate data on this heterogenous population. We conducted a registry study of immunocompromised individuals with polymerase chain reaction (PCR)-confirmed SARS-CoV-2 infection from March-October 2020 in Sydney, Australia to understand clinical and laboratory outcomes in this population prior to the emergence of the Delta variant. 27 participants were enrolled into the study including people with a haematologic oncologic conditions (n = 12), secondary immunosuppression (N = 8) and those with primary or acquired immunodeficiency (i.e. HIV; N = 7). All participants had symptomatic COVID-19 with the most common features being cough (64%), fever (52%) and headache (40%). Five patients demonstrated delayed SARS-CoV-2 clearance lasting three weeks to three months. The mortality rate in this study was 7% compared to 1.3% in the state of New South Wales Australia during the same period. This study provides data from the first eight months of the pandemic on COVID-19 outcomes in at-risk patient groups.

Made to measure-Selecting outcomes in aneurysmal subarachnoid hemorrhage research.

There has been limited new high-level evidence generated to guide aneurysmal subarachnoid hemorrhage (aSAH) management in the past decade. The choice of outcome measures used in aSAH clinical trials may be one of the factors hindering progress. In this narrative review we consider the current process for determining "what" to measure in aSAH and identify some of the shortcomings of these approaches. A consideration of the unique clinical course of aSAH is then discussed and how this impacts on selecting the best timepoints to assess change in the chosen constructs. We also review the how to critically appraise different measurement instruments and some of the issues with how these are applied in the context of aSAH. We conclude with current initiatives to improve outcome selection in aSAH and future directions in the research agenda.

Frontline workers: Mediators of mucosal immunity in community acquired pneumonia and COVID-19.

The current COVID-19 pandemic has highlighted a need to further understand lung mucosal immunity to reduce the burden of community acquired pneumonia, including that caused by the SARS-CoV-2 virus. Local mucosal immunity provides the first line of defence against respiratory pathogens, however very little is known about the mechanisms involved, with a majority of literature on respiratory infections based on the examination of peripheral blood. The mortality for severe community acquired pneumonia has been rising annually, even prior to the current pandemic, highlighting a significant need to increase knowledge, understanding and research in this field. In this review we profile key mediators of lung mucosal immunity, the dysfunction that occurs in the diseased lung microenvironment including the imbalance of inflammatory mediators and dysbiosis of the local microbiome. A greater understanding of lung tissue-based immunity may lead to improved diagnostic and prognostic procedures and novel treatment strategies aimed at reducing the disease burden of community acquired pneumonia, avoiding the systemic manifestations of infection and excess morbidity and mortality.

Fire in the belly: A scoping review of the immunopathological mechanisms of acute pancreatitis.

Introduction: Acute pancreatitis (AP) is characterised by an inflammatory response that in its most severe form can cause a systemic dysregulated immune response and progression to acute multi-organ dysfunction. The pathobiology of the disease is unclear and as a result no targeted, disease-modifying therapies exist. We performed a scoping review of data pertaining to the human immunology of AP to summarise the current field and to identify future research opportunities. Methods: A scoping review of all clinical studies of AP immunology was performed across multiple databases. Studies were included if they were human studies of AP with an immunological outcome or intervention. Results: 205 studies met the inclusion criteria for the review. Severe AP is characterised by significant immune dysregulation compared to the milder form of the disease. Broadly, this immune dysfunction was categorised into: innate immune responses (including profound release of damage-associated molecular patterns and heightened activity of pattern recognition receptors), cytokine profile dysregulation (particularly IL-1, 6, 10 and TNF-α), lymphocyte abnormalities, paradoxical immunosuppression (including HLA-DR suppression and increased co-inhibitory molecule expression), and failure of the intestinal barrier function. Studies including interventions were also included. Several limitations in the existing literature have been identified; consolidation and consistency across studies is required if progress is to be made in our understanding of this disease. Conclusions: AP, particularly the more severe spectrum of the disease, is characterised by a multifaceted immune response that drives tissue injury and contributes to the associated morbidity and mortality. Significant work is required to develop our understanding of the immunopathology of this disease if disease-modifying therapies are to be established.

Direct Observations of Twin Formation Dynamics in Binary Semiconductors.

With the increased demand for controlled deterministic growth of III-V semiconductors at the nanoscale, the impact and interest of understanding defect formation and crystal structure switching becomes increasingly important. Vapor-liquid-solid (VLS) growth of semiconductor nanocrystals is an important mechanism for controlling and studying the formation of individual crystal layers and stacking defects. Using in situ studies, combining atomic resolution of transmission electron microscopy and controlled VLS crystal growth using metal organic chemical vapor deposition, we investigate the simplest achievable change in atomic layer stacking-single twinned layers formed in GaAs. Using Au-assisted GaAs nanowires of various diameters, we study the formation of individual layers with atomic resolution to reveal the growth difference in forming a twin defect. We determine that the formation of a twinned layer occurs significantly more slowly than that of a normal crystal layer. To understand this, we conduct thermodynamic modeling and determine that the propagation of a twin is limited by the energy cost of forming the twin interface. Finally, we determine that the slower propagation of twinned layers increases the probability of additional layers nucleating, such that multiple layers grow simultaneously. This observation challenges the current understanding that continuous uniform epitaxial growth, especially in the case of liquid-metal assisted nanowires, proceeds one single layer at a time and that its progression is limited by the nucleation rate.

Prioritizing outcome measures after aneurysmal subarachnoid hemorrhage: A q-sort survey of patients, health care providers and researchers.

Objective: To understand which outcome measures patients and their families, health care providers, and researchers prioritize after aneurysmal subarachnoid hemorrhage (aSAH). Methods: We conducted a cross-sectional q-sort survey with participants from three key stakeholder groups. Potential outcomes were identified from interviews and focus groups. Participants were purposively sampled to achieve diversity based on stakeholder group, geography, and profession. Respondents sorted 27 outcomes in a quasi-normally distributed grid (Q-Sort) from most to least important. Principal components analysis was used to determine similarities in the way participants sorted the outcome measures resulting in distinct groupings. Overall rankings were also reported. Results: 112 participants were invited. 70 responded and 64 participants from 25 different countries completed a Q-sort. Balanced stakeholder representation was achieved. Five distinct patterns were identified based on survival, pathophysiological, psychological, resource use, and functional outcome measures. Quality of life as reported by the patient was the highest ranked outcome measure followed by independence and functional measures. Survival and biomedical outcomes were ranked in the middle and cost measures last. Conclusions: In this diverse sample of key stakeholders, we characterized several distinct perspectives with respect to outcome measure selection in aSAH. We did not identify a clear pattern of opinion based on stakeholder group or other participant characteristics. Patient-reported measure of quality of life was ranked the most important overall with function and independence also highly rated. These results will assist study design and inform efforts to improve outcome selection in aSAH research.

Magnetic Bloch oscillations and domain wall dynamics in a near-Ising ferromagnetic chain.

When charged particles in periodic lattices are subjected to a constant electric field, they respond by oscillating. Here we demonstrate that the magnetic analogue of these Bloch oscillations are realised in a ferromagnetic easy axis chain. In this case, the "particles" undergoing oscillatory motion in the presence of a magnetic field are domain walls. Inelastic neutron scattering reveals three distinct components of the low energy spin-dynamics including a signature Bloch oscillation mode. Using parameter-free theoretical calculations, we are able to account for all features in the excitation spectrum, thus providing detailed insights into the complex dynamics in spin-anisotropic chains.

HIV vaccines: progress to date.

The quest for an effective and safe HIV-1 vaccine has been and still is the aspiration of many scientists and clinicians worldwide. Until recently, the hopes for an effective vaccine were thwarted by the disappointing results and early termination in September 2007 of the STEP study, which saw a subgroup of male vaccine recipients at an increased risk of HIV-1 infection, and the failure of earlier trials of vaccines based on recombinant envelope proteins to provide any level of protection. The results of the STEP study raised important questions in the field of HIV vaccines, including the use of recombinant adenovirus vectors as immunogens, the rationale for the development of T-cell-based vaccines and the development pathway for these vaccines, in terms of assessment of immunogenicity and the challenge models used. The study of neutralizing antibodies has demonstrated that the induction of high-titre, broadly neutralizing antibodies in the majority of recipients is likely to be highly problematic. However, the results of the RV144 Thai trial released in September 2009 have brought new optimism to the field. This study employed envelope-based immunogens delivered as a priming vaccination with a recombinant poxvirus vector and boosting with recombinant proteins. This regimen provided modest protection to HIV-1 infection in a low-risk population. Although the correlates of protection are currently unknown, extensive studies are underway to try to determine these. Neutralizing antibodies were not induced in the RV144 study; however, considerable titres of binding antibodies to HIV-1 viral envelope (Env) were. It is speculated that these antibodies may have provided a means of protection by a mechanism such as antibody-dependent cell-mediated cytotoxicity. In addition, no CD8+ T-cell responses were induced, but robust CD4+ T-cell responses were, and correlates of protection are being sought by analysing the quality of this aspect of the vaccine-induced immune response. The current paradigm for an optimal HIV-1 vaccine is to design immunogens and vaccination protocols that allow the induction of both broadly neutralizing humoral and broadly reactive and effective cell-mediated immunity, to act at sites of possible infection and post-infection, respectively. However, this is challenged by the results of the RV144 trial as neither of these responses were induced but modest protection was observed. Understanding the biology and immunopathology of HIV-1 early following infection, its modes of transmission and the human immune system's response to the virus should aid in the rational design of vaccines of increased efficacy.