COVID-19 symptoms at hospital admission vary with age and sex: results from the ISARIC prospective multinational observational study

Background: The ISARIC prospective multinational observational study is the largest cohort of hospitalized patients with COVID-19. We present relationships of age, sex, and nationality to presenting symptoms. Methods: International, prospective observational study of 60 109 hospitalized symptomatic patients with laboratory-confirmed COVID-19 recruited from 43 countries between 30 January and 3 August 2020. Logistic regression was performed to evaluate relationships of age and sex to published COVID-19 case definitions and the most commonly reported symptoms. Results: ‘Typical’ symptoms of fever (69%), cough (68%) and shortness of breath (66%) were the most commonly reported. 92% of patients experienced at least one of these. Prevalence of typical symptoms was greatest in 30- to 60-year-olds (respectively 80, 79, 69%; at least one 95%). They were reported less frequently in children (≤ 18 years: 69, 48, 23; 85%), older adults (≥ 70 years: 61, 62, 65; 90%), and women (66, 66, 64; 90%; vs. men 71, 70, 67; 93%, each P < 0.001). The most common atypical presentations under 60 years of age were nausea and vomiting and abdominal pain, and over 60 years was confusion. Regression models showed significant differences in symptoms with sex, age and country. Interpretation: This international collaboration has allowed us to report reliable symptom data from the largest cohort of patients admitted to hospital with COVID-19. Adults over 60 and children admitted to hospital with COVID-19 are less likely to present with typical symptoms. Nausea and vomiting are common atypical presentations under 30 years. Confusion is a frequent atypical presentation of COVID-19 in adults over 60 years. Women are less likely to experience typical symptoms than men

Evidence of altered prefrontal-thalamic circuitry in schizophrenia: An optimised diffusion MRI study

MRI diffusion tensor imaging (DTI), optimized for measuring the trace of the diffusion tensor, was used to investigate microstructural changes in the brains of 12 individuals with schizophrenia compared with 12 matched control subjects. To control for the effects of anatomic variation between subject groups, all participants' diffusion images were non-linearly registered to standard anatomical space. Significant statistical differences in mean diffusivity (MD) measures between the two groups were determined on a pixel-by-pixel basis, using Gaussian random field theory. We found significantly elevated MD measures within temporal, parietal and prefrontal cortical regions in the schizophrenia group (P > 0.001), especially within the medial frontal gyrus and anterior cingulate. The dorsal medial and anterior nucleus of the thalamus, including the caudate, also exhibited significantly increased MD in the schizophrenia group (P > 0.001). This study has shown for the first time that MD measures offer an alternative strategy for investigating altered prefrontal-thalamic circuitry in schizophrenia. (c) 2006 Elsevier Inc. All rights reserved

Determining the Level and Location of Functional Groups on Few-Layer Graphene and Their Effect on the Mechanical Properties of Nanocomposites

Graphene is a highly desirable material for a variety of applications; in the case of nanocomposites, it can be functionalized and added as a nanofiller to alter the ultimate product properties, such as tensile strength. However, often the material properties of the functionalized graphene and the location of any chemical species, attached via different functionalization processes, are not known. Thus, it is not necessarily understood why improvements in product performance are achieved, which hinders the rate of product development. Here, a commercially available powder containing few-layer graphene (FLG) flakes is characterized before and after plasma or chemical functionalization with either nitrogen or oxygen species. A range of measurement techniques, including tip-enhanced Raman spectroscopy (TERS), time-of-flight secondary ion mass spectrometry (ToF-SIMS), and NanoSIMS, were used to examine the physical and chemical changes in the FLG material at both the micro- and nanoscale. This is the first reported TERS imaging of commercially available FLG flakes of submicron lateral size, revealing the location of the defects (edge versus basal plane) and variations in the level of functionalization. Graphene-polymer composites were then produced, and the dispersion of the graphitic material in the matrix was visualized using ToF-SIMS. Finally, mechanical testing of the composites demonstrated that the final product performance could be enhanced but differed depending on the properties of the original graphitic material

Clean assembly of van der Waals heterostructures using silicon nitride membranes

Van der Waals heterostructures are fabricated by layer-by-layer assembly of individual two-dimensional materials and can be used to create a wide range of electronic devices. However, current assembly techniques typically use polymeric supports, which limit the cleanliness—and thus the electronic performance—of such devices. Here, we report a polymer-free technique for assembling van der Waals heterostructures using flexible silicon nitride membranes. Eliminating the polymeric supports allows the heterostructures to be fabricated in harsher environmental conditions (incompatible with a polymer) such as at temperatures of up to 600 °C, in organic solvents and in ultra-high vacuum. The resulting heterostructures have high-quality interfaces without interlayer contamination and exhibit strong electronic and optoelectronic behaviour. We use the technique to assemble twisted-graphene heterostructures in ultra-high vacuum, resulting in a tenfold improvement in moiré superlattice homogeneity compared to conventional transfer techniques.<br/

Clean assembly of van der Waals heterostructures using silicon nitride membranes

Van der Waals heterostructures are fabricated by layer-by-layer assembly of individual two-dimensional materials and can be used to create a wide range of electronic devices. However, current assembly techniques typically use polymeric supports, which limit the cleanliness—and thus the electronic performance—of such devices. Here, we report a polymer-free technique for assembling van der Waals heterostructures using flexible silicon nitride membranes. Eliminating the polymeric supports allows the heterostructures to be fabricated in harsher environmental conditions (incompatible with a polymer) such as at temperatures of up to 600 °C, in organic solvents and in ultra-high vacuum. The resulting heterostructures have high-quality interfaces without interlayer contamination and exhibit strong electronic and optoelectronic behaviour. We use the technique to assemble twisted-graphene heterostructures in ultra-high vacuum, resulting in a tenfold improvement in moiré superlattice homogeneity compared to conventional transfer techniques