Particle size of tobacco mosaic virus

Publication authorized June 22, 1938.Includes bibliographical references (pages 17-18)

Discovery of Extended Blue Horizontal Branches in Two Metal-Rich Globular Clusters

We have used WFPC2 to construct B, V color-magnitude diagrams of four metal-rich globular clusters, NGC 104 (47 Tuc), NGC 5927, NGC 6388, and NGC 6441. All four clusters have well populated red horizontal branches (RHB), as expected for their metallicity. However, NGC 6388 and 6441 also exhibit a prominent blue HB (BHB) extension, including stars reaching as faint in V as the turnoff luminosity. This discovery demonstrates directly for the first time that a major population of hot HB stars can exist in old, metal-rich systems. This may have important implications for the interpretation of the integrated spectra of elliptical galaxies. The cause of the phenomenon remains uncertain. We examine the possibility that NGC 6388 and 6441 are older than the other clusters, but a simple difference in age may not be sufficient to produce the observed distributions along the HB. The high central densities in NGC 6388 and 6441 suggest that the existence of the blue HB (BHB) tails might be caused by stellar interactions in the dense cores of these clusters, which we calculate to have two of the highest collision rates among globular clusters in the Galaxy. Tidal collisions might act in various ways to enhance loss of envelope mass, and therefore populate the blue side of the HB. However, the relative frequency of tidal collisions does not seem large enough (compared to that of the clusters with pure RHBs) to account for such a drastic difference in HB morphology. While a combination of an age difference and dynamical interactions may help, prima facie the lack of a radial gradient in the BHB/RHB star ratio seems to argue against dynamical effects playing a role.Comment: LaTeX, includes one Postscript figure. To appear in ApJ

What is the relationship between photospheric flow fields and solar flares?

We estimated photospheric velocities by separately applying the Fourier Local Correlation Tracking (FLCT) and Differential Affine Velocity Estimator (DAVE) methods to 2708 co-registered pairs of SOHO/MDI magnetograms, with nominal 96-minute cadence and ~2" pixels, from 46 active regions (ARs) from 1996-1998 over the time interval t45 when each AR was within 45^o of disk center. For each magnetogram pair, we computed the average estimated radial magnetic field, B; and each tracking method produced an independently estimated flow field, u. We then quantitatively characterized these magnetic and flow fields by computing several extensive and intensive properties of each; extensive properties scale with AR size, while intensive properties do not depend directly on AR size. Intensive flow properties included moments of speeds, horizontal divergences, and radial curls; extensive flow properties included sums of these properties over each AR, and a crude proxy for the ideal Poynting flux, the total |u| B^2. Several magnetic quantities were also computed, including: total unsigned flux; a measure of the amount of unsigned flux near strong-field polarity inversion lines, R; and the total B^2. Next, using correlation and discriminant analysis, we investigated the associations between these properties and flares from the GOES flare catalog, when averaged over both t45 and shorter time windows, of 6 and 24 hours. We found R and total |u| B^2 to be most strongly associated with flares; no intensive flow properties were strongly associated with flares.Comment: 57 pages, 13 figures; revised content; added URL to manuscript with higher-quality image

Families' social backgrounds matter : socio-economic factors, home learning and young children's language, literacy and social outcomes

Parental support with children's learning is considered to be one pathway through which socio-economic factors influence child competencies. Utilising a national longitudinal sample from the Millennium Cohort Study, this study examined the relationship between home learning and parents' socio-economic status and their impact on young children's language/literacy and socio-emotional competence. The findings consistently showed that, irrespective of socio-economic status, parents engaged with various learning activities (except reading) roughly equally. The socio-economic factors examined in this study, i.e., family income and maternal educational qualifications, were found to have a stronger effect on children's language/literacy than on social-emotional competence. Socio-economic disadvantage, lack of maternal educational qualifications in particular, remained powerful in influencing competencies in children aged three and at the start of primary school. For children in the first decade of this century in England, these findings have equity implications, especially as the socio-economic gap in our society widens

Shaping the global communications milieu : the EU's influence on internet and telecommunications governance

This article evaluates the European Union's (EU) influence in shaping the global governance for telecommunications and the Internet. Through analysing EU behaviour within an actorness framework, we demonstrate how the external opportunity structure and the EU's internal environment has impacted on its ability to exert and maximize its presence in order to meet its goals and aims in these two very different sub-sectors of global communications in terms of evolution and development. Such a comparison of EU actorness, we argue, is revealing in terms of uncovering the underlying factors and conditions that allow the EU to influence two important and dynamic communications sub-sectors

Development and validation of anthropometric prediction equations for estimation of lean body mass and appendicular lean soft tissue in Indian men and women.

Lean body mass (LBM) and muscle mass remain difficult to quantify in large epidemiological studies due to the unavailability of inexpensive methods. We therefore developed anthropometric prediction equations to estimate the LBM and appendicular lean soft tissue (ALST) using dual-energy X-ray absorptiometry (DXA) as a reference method. Healthy volunteers (n = 2,220; 36% women; age 18-79 yr), representing a wide range of body mass index (14-44 kg/m(2)), participated in this study. Their LBM, including ALST, was assessed by DXA along with anthropometric measurements. The sample was divided into prediction (60%) and validation (40%) sets. In the prediction set, a number of prediction models were constructed using DXA-measured LBM and ALST estimates as dependent variables and a combination of anthropometric indices as independent variables. These equations were cross-validated in the validation set. Simple equations using age, height, and weight explained >90% variation in the LBM and ALST in both men and women. Additional variables (hip and limb circumferences and sum of skinfold thicknesses) increased the explained variation by 5-8% in the fully adjusted models predicting LBM and ALST. More complex equations using all of the above anthropometric variables could predict the DXA-measured LBM and ALST accurately, as indicated by low standard error of the estimate (LBM: 1.47 kg and 1.63 kg for men and women, respectively), as well as good agreement by Bland-Altman analyses (Bland JM, Altman D. Lancet 1: 307-310, 1986). These equations could be a valuable tool in large epidemiological studies assessing these body compartments in Indians and other population groups with similar body composition

Cohesin-dependent regulation of gene expression during differentiation is lost in cohesin-mutated myeloid malignancies.

Cohesin complex disruption alters gene expression, and cohesin mutations are common in myeloid neoplasia, suggesting a critical role in hematopoiesis. Here, we explore cohesin dynamics and regulation of hematopoietic stem cell homeostasis and differentiation. Cohesin binding increases at active regulatory elements only during erythroid differentiation. Prior binding of the repressive Ets transcription factor Etv6 predicts cohesin binding at these elements and Etv6 interacts with cohesin at chromatin. Depletion of cohesin severely impairs erythroid differentiation, particularly at Etv6-prebound loci, but augments self-renewal programs. Together with corroborative findings in acute myeloid leukemia and myelodysplastic syndrome patient samples, these data suggest cohesin-mediated alleviation of Etv6 repression is required for dynamic expression at critical erythroid genes during differentiation and how this may be perturbed in myeloid malignancies

Methods to disinfect and decontaminate SARS-CoV-2: a systematic review of in vitro studies

Background: Cleaning is a major control component for outbreaks of infection. However, for the SARS-CoV-2 pandemic, there is limited specific guidance regarding the proper disinfection methods that should be used. Methods: We conducted a systematic review of the literature on cleaning, disinfection or decontamination methods in the prevention of SARS-CoV-2. Results: A total of 27 studies were included, reporting a variety of methods with which the effectiveness of interventions were assessed. Virus was inoculated onto different types of material including masks, nasopharyngeal swabs, serum, laboratory plates and simulated saliva, tears or nasal fluid and then interventions were applied in an attempt to eliminate the virus including chemical, ultraviolet (UV) light irradiation, and heat and humidity. At body temperature (37°C) there is evidence that the virus will not be detectable after 2 days but this can be reduced to non-detection at 30 min at 56°C, 15 min at 65°C and 2 min at 98°C. Different experimental methods testing UV light have shown that it can inactivate the virus. Light of 254–365 nm has been used, including simulated sunlight. Many chemical agents including bleach, hand sanitiser, hand wash, soap, ethanol, isopropanol, guandinium thiocynate/t-octylphenoxypolyethoxyethanol, formaldehyde, povidone-iodine, 0.05% chlorhexidine, 0.1% benzalkonium chloride, acidic electrolysed water, Clyraguard copper iodine complex and hydrogen peroxide vapour have been shown to disinfect SARS-CoV-2. Conclusions: Heating, UV light irradiation and chemicals can be used to inactivate SARS-CoV-2 but there is insufficient evidence to support one measure over others in clinical practice