Silicon dominates contemporary solar cell technologies
. But when absorbing photons, silicon (like other semiconductors) wastes energy in excess of its bandgap
. Reducing these thermalization losses ...and enabling better sensitivity to light is possible by sensitizing the silicon solar cell using singlet exciton fission, in which two excited states with triplet spin character (triplet excitons) are generated from a photoexcited state of higher energy with singlet spin character (a singlet exciton)
. Singlet exciton fission in the molecular semiconductor tetracene is known to generate triplet excitons that are energetically matched to the silicon bandgap
. When the triplet excitons are transferred to silicon they create additional electron-hole pairs, promising to increase cell efficiencies from the single-junction limit of 29 per cent to as high as 35 per cent
. Here we reduce the thickness of the protective hafnium oxynitride layer at the surface of a silicon solar cell to just eight angstroms, using electric-field-effect passivation to enable the efficient energy transfer of the triplet excitons formed in the tetracene. The maximum combined yield of the fission in tetracene and the energy transfer to silicon is around 133 per cent, establishing the potential of singlet exciton fission to increase the efficiencies of silicon solar cells and reduce the cost of the energy that they generate.
Although increasingly popular as a laboratory species, very little is known about the peripheral auditory system of the naked mole-rat, Heterocephalus glaber. In this study, middle and inner ears of ...naked mole-rats of a range of ages were examined using micro-computed tomography and dissection. The ears of five other bathyergid species (Bathyergus suillus, Cryptomys hottentotus, Fukomys micklemi, Georychus capensis and Heliophobius argenteocinereus) were examined for comparative purposes. The middle ears of bathyergids show features commonly found in other members of the Ctenohystrica rodent clade, including a fused malleus and incus, a synovial stapedio-vestibular articulation and the loss of the stapedius muscle. Heterocephalus deviates morphologically from the other bathyergids examined in that it has a more complex mastoid cavity structure, poorly-ossified processes of the malleus and incus, a 'columelliform' stapes and fewer cochlear turns. Bathyergids have semicircular canals with unusually wide diameters relative to their radii of curvature. How the lateral semicircular canal reaches the vestibule differs between species. Heterocephalus has much more limited high-frequency hearing than would be predicted from its small ear structures. The spongy bone forming its ossicular processes, the weak incudo-stapedial articulation, the columelliform stapes and (compared to other bathyergids) reduced cochlear coiling are all potentially degenerate features which might reflect a lack of selective pressure on its peripheral auditory system. Substantial intraspecific differences were found in certain middle and inner ear structures, which might also result from relaxed selective pressures. However, such interpretations must be treated with caution in the absence of experimental evidence.
Vaccine efforts to combat the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which is responsible for the current coronavirus disease 2019 (COVID-19) pandemic, are focused on ...SARS-CoV-2 spike glycoprotein, the primary target for neutralizing antibodies. We performed cryo-election microscopy and site-specific glycan analysis of one of the leading subunit vaccine candidates from Novavax, which is based on a full-length spike protein formulated in polysorbate 80 detergent. Our studies reveal a stable prefusion conformation of the spike immunogen with slight differences in the S1 subunit compared with published spike ectodomain structures. We also observed interactions between the spike trimers, allowing formation of higher-order spike complexes. This study confirms the structural integrity of the full-length spike protein immunogen and provides a basis for interpreting immune responses to this multivalent nanoparticle immunogen.
To examine trends in state-level policy support for sexual minorities and HIV outcomes among men who have sex with men (MSM).
This longitudinal analysis linked state-level policy support for sexual ...minorities N = 94 metropolitan statistical areas (MSAs) in 38 states to 7 years of data (2008-2014) from the Centers for Disease Control and Prevention on HIV outcomes among MSM. Using latent growth mixture modeling, we combined 11 state-level policies (eg, nondiscrimination laws including sexual orientation as a protected class) from 1999 to 2014, deriving the following 3 latent groups: consistently low policy support, consistently high policy support, and increasing trajectory of policy support. Outcomes were HIV diagnoses per 10,000 MSM, late diagnoses (number of deaths within 12 months of HIV diagnosis and AIDS diagnoses within 3 months of HIV diagnosis) per 10,000 MSM, AIDS diagnoses per 10,000 MSM with HIV, and AIDS-related mortality per 10,000 MSM with AIDS.
Compared with MSAs in states with low policy support and increasing policy support for sexual minorities, MSAs in states with the highest level of policy support had lower risks of HIV diagnoses risk difference (RD) = -37.9, 95% confidence interval (CI): -54.7 to -21.0, late diagnoses (RD = -12.5, 95% CI: -20.4 to -4.7), and AIDS-related mortality (RD = -33.7, 95% CI: -61.2 to -6.2), controlling for time and 7 MSA-level covariates. In low policy support states, 27% of HIV diagnoses, 21% of late diagnoses, and 10% of AIDS deaths among MSM were attributable to the policy climate.
The state-level policy climate related to sexual minorities was associated with HIV health outcomes among MSM and could be a potential public health tool for HIV prevention and care.
The bone cancer osteosarcoma, found mainly in adolescents, routinely forms around the growth plate/metaphysis of long bones. Bone marrow composition changes with age, shifting from a more ...hematopoietic to an adipocyte-rich tissue. This conversion occurs in the metaphysis during adolescence, implicating a link between bone marrow conversion and osteosarcoma initiation. To assess this, the tri-lineage differentiation potential of human bone marrow stromal cells (HBMSCs) isolated from the femoral diaphysis/metaphysis (FD) and epiphysis (FE) was characterized and compared to two osteosarcoma cell lines, Saos-2 and MG63. Compared to FE-cells, FD-cells showed an increase in tri-lineage differentiation. Additionally, differences were found between the Saos-2 cells exhibiting higher levels of osteogenic differentiation, lower adipogenic differentiation, and a more developed chondrogenic phenotype than MG63, with the Saos-2 being more comparable to FD-derived HBMSCs. The differences found between the FD and FE derived cells are consistent with the FD region containing more hematopoietic tissue compared to the FE. This may be related to the similarities between FD-derived cells and Saos-2 cells during osteogenic and chondrogenic differentiation. These studies reveal distinct differences in the tri-lineage differentiations of 'hematopoietic' and 'adipocyte rich' bone marrow, which correlate with specific characteristics of the two osteosarcoma cell lines.
Abstract
Background
Respiratory tract infections are common, often seasonal, and caused by multiple pathogens. We assessed whether seasonal respiratory illness patterns changed during the COVID-19 ...pandemic.
Methods
We categorized emergency department (ED) visits reported to the National Syndromic Surveillance Program according to chief complaints and diagnosis codes, excluding visits with diagnosed SARS-CoV-2 infections. For each week during 1 March 2020 through 26 December 2020 (“pandemic period”), we compared the proportion of ED visits in each respiratory category with the proportion of visits in that category during the corresponding weeks of 2017–2019 (“pre–pandemic period”). We analyzed positivity of respiratory viral tests from 2 independent clinical laboratories.
Results
During March 2020, cough, shortness of breath, and influenza-like illness accounted for twice as many ED visits compared with the pre–pandemic period. During the last 4 months of 2020, all respiratory conditions, except shortness of breath, accounted for a smaller proportion of ED visits than during the pre–pandemic period. Percent positivity for influenza virus, respiratory syncytial virus, human parainfluenza virus, adenoviruses, and human metapneumovirus was lower in 2020 than 2019. Although test volume decreased, percent positivity was higher for rhinovirus/enterovirus during the final weeks of 2020 compared with 2019, with ED visits similar to the pre–pandemic period.
Conclusions
Broad reductions in respiratory test positivity and respiratory ED visits (excluding COVID-19) occurred during 2020. Interventions for mitigating spread of SARS-CoV-2 likely also reduced transmission of other pathogens. Timely surveillance is needed to understand community health threats, particularly when current trends deviate from seasonal norms.
Autism spectrum disorder (ASD) is genetically heterogeneous with convergent symptomatology, suggesting common dysregulated pathways. In this study, we analyzed brain transcriptional changes in five ...mouse models of Pitt-Hopkins syndrome (PTHS), a syndromic form of ASD caused by mutations in the TCF4 gene, but not the TCF7L2 gene. Analyses of differentially expressed genes (DEGs) highlighted oligodendrocyte (OL) dysregulation, which we confirmed in two additional mouse models of syndromic ASD (Pten
and Mecp2
). The PTHS mouse models showed cell-autonomous reductions in OL numbers and myelination, functionally confirming OL transcriptional signatures. We also integrated PTHS mouse model DEGs with human idiopathic ASD postmortem brain RNA-sequencing data and found significant enrichment of overlapping DEGs and common myelination-associated pathways. Notably, DEGs from syndromic ASD mouse models and reduced deconvoluted OL numbers distinguished human idiopathic ASD cases from controls across three postmortem brain data sets. These results implicate disruptions in OL biology as a cellular mechanism in ASD pathology.
From midlife onwards, age stereotypes increasingly underlie social judgments and contribute to age-based discrimination. Whereas many studies compare differences between young and older adults in ...reports of age discrimination or sensitivity to age stereotypes, few consider age group differences among adults over 50. We form subgroups corresponding to social age group membership (early midlife, late midlife, young old, oldest old) and examine differences in reported experiences of everyday age discrimination and associations with self-perceptions of aging.
Using cross-sectional and longitudinal data from the Health and Retirement Study (HRS: N = 15,071; M Age = 68, range 50-101), multivariate logistic regression was used to examine experiences of everyday discrimination attributed to age, and associations between age discrimination and self-perceptions of aging, in four age groups: early midlife, late midlife, young old, oldest old.
People in the early midlife group (aged 50-59) reported more experiences of unfair treatment than the older age groups but were less likely to attribute their experiences to age discrimination. After controlling for covariates, individuals in all age groups who perceived their own aging positively were less likely to report experiences of age discrimination. The magnitude of this effect, however, was greatest in the early midlife group.
Findings support proposals that midlife is a pivotal life period when individuals adjust to life events and social role transitions. Future longitudinal studies will provide further insight into whether positive self-perceptions of aging are especially important in this phase of the life course.
Increasing evidence suggests that inflammation plays a central role in driving joint pathology in certain patients with osteoarthritis (OA). Since many patients with OA are obese and increased ...adiposity is associated with chronic inflammation, we investigated whether obese patients with hip OA exhibited differential pro-inflammatory cytokine signalling and peripheral and local lymphocyte populations, compared to normal weight hip OA patients. No differences in either peripheral blood or local lymphocyte populations were found between obese and normal-weight hip OA patients. However, synovial fibroblasts from obese OA patients were found to secrete greater amounts of the pro-inflammatory cytokine IL-6, compared to those from normal-weight patients (p < 0.05), which reflected the greater levels of IL-6 detected in the synovial fluid of the obese OA patients. Investigation into the inflammatory mechanism demonstrated that IL-6 secretion from synovial fibroblasts was induced by chondrocyte-derived IL-6. Furthermore, this IL-6 inflammatory response, mediated by chondrocyte-synovial fibroblast cross-talk, was enhanced by the obesity-related adipokine leptin. This study suggests that obesity enhances the cross-talk between chondrocytes and synovial fibroblasts via raised levels of the pro-inflammatory adipokine leptin, leading to greater production of IL-6 in OA patients.
This tutorial describes a system for rapidly yet rigorously assessing the quality of randomized controlled trials (RCTs). The system has 7 criteria, represented by the acronym "BIS FOES." The BIS ...FOES system directs readers to assess RCTs based on the following 7 criteria: the RCT's use (or not) of effective (1) Blinding; the RCT's use (or not) of (2) Intent-to-Treat Analysis; the RCT's (3) Size and other information reflecting the effectiveness of randomization; the amount of sample lost during (4) Follow-up; the (5) Outcomes examined by the RCT (specifically, the outcome measures used by the RCT), the (6) Effects reported (ie, the statistical and clinical significance of the RCT's primary, secondary, and safety findings), and any (7) Special Considerations (ie, additional strengths, limitations, or notable features of the RCT). The first 6 criteria are of basic importance to the assessment of every RCT, whereas the Special Considerations criteria allows the system to be expanded to include virtually any other important aspect of the RCT. This tutorial explains the importance of these criteria and how to assess them. This tutorial also describes how many BIS FOES criteria can be initially assessed from the RCT Abstract while also directing readers to specific locations in the RCT article where additional important information can be found. We hope that the BIS FOES system will help healthcare trainees, but also potentially clinicians, researchers, and the general public, rapidly and thoroughly assess RCTs.
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