The Turbulence Spectrum of Molecular Clouds in the Galactic Ring Survey: A Density-Dependent PCA Calibration

Turbulence plays a major role in the formation and evolution of molecular clouds. The problem is that turbulent velocities are convolved with the density of an observed region. To correct for this convolution, we investigate the relation between the turbulence spectrum of model clouds, and the statistics of their synthetic observations obtained from Principal Component Analysis (PCA). We apply PCA to spectral maps generated from simulated density and velocity fields, obtained from hydrodynamic simulations of supersonic turbulence, and from fractional Brownian motion fields with varying velocity, density spectra, and density dispersion. We examine the dependence of the slope of the PCA structure function, alpha_PCA, on intermittency, on the turbulence velocity (beta_v) and density (beta_n) spectral indexes, and on density dispersion. We find that PCA is insensitive to beta_n and to the log-density dispersion sigma_s, provided sigma_s 2, alpha_PCA increases with sigma_s due to the intermittent sampling of the velocity field by the density field. The PCA calibration also depends on intermittency. We derive a PCA calibration based on fBms with sigma_s<2 and apply it to 367 CO spectral maps of molecular clouds in the Galactic Ring Survey. The average slope of the PCA structure function, =0.62\pm0.2, is consistent with the hydrodynamic simulations and leads to a turbulence velocity exponent =2.06\pm0.6 for a non-intermittent, low density dispersion flow. Accounting for intermittency and density dispersion, the coincidence between the PCA slope of the GRS clouds and the hydrodynamic simulations suggests beta_v~1.9, consistent with both Burgers and compressible intermittent turbulence

Change in Anti- gp120 Human Monoclonal Antibody Isotype Significantly Improves HIV-1 Neutralization

HIV vaccine efforts tend to focus on the induction of IgG neutralizing antibodies. In part, this may stem from the observations that most HIV infected individuals fail to produce significant mucosal IgA. However, this is unlike most other infections and in turn it can be argued that mucosal IgA with appropriate function and specificity may contribute significantly to the prevention of HIV transmission. To explore this, we previously isotype switched F425A1g8, an anti-HIV CD4i human monoclonal antibody that binds to epitopes exposed upon CD4 binding (CD4i) The VH and VL chains were amplified from the IgG hybridoma and inserted into IgA1 or IgA2 and IgKappa vectors respectively. Stable cells lines were produced and antibody was collected and purified. Initial results showed that the IgA1 variant neutralized a number of HIV-1 isolates better than its parental form IgG1. We believe the increased neutralization of HIV is mainly due to the structural differences between IgG1 and IgA1. We hypothesize that the extended hinge of IgA1 may increase segmental flexibility and change the interaction of antibody with CD4i epitopes of the HIV, resulting in greater avidity. To look at this further, we have generated monomeric and dimeric IgA1 and IgA2 variants of three different CD4i antibodies: F425A1g8, 17b and E51. All antibody variants will be tested for immumoreactivity, HIV neutralization, prevention of transmission and ADCVI activity. Consistent with our previous results, there are significant differences in functional activity of the other CD4i antibodies with IgA1 more effective than the IgA2 variants. Additional activities will contribute to the hypothesis that the extended hinge region of the IgA1 antibody increases the antibodies ability to access the CD4i epitopes upon HIV-1 binding to CD4. These studies should impact on the design of active and passive immunotherapy and the prevention of HIV transmission

Re-examining Larson's Scaling Relationships in Galactic Molecular Clouds

The properties of Galactic molecular clouds tabulated by Solomon etal (1987) (SRBY) are re-examined using the Boston University-FCRAO Galactic Ring Survey of 13CO J=1-0 emission. These new data provide a lower opacity tracer of molecular clouds and improved angular and spectral resolution than previous surveys of molecular line emission along the Galactic Plane. We calculate GMC masses within the SRBY cloud boundaries assuming LTE conditions throughout the cloud and a constant H2 to 13CO abundance, while accounting for the variation of the 12C/13C with Galacto-centric radius. The LTE derived masses are typically five times smaller than the SRBY virial masses. The corresponding median mass surface density of molecular hydrogen for this sample is 42 Msun/pc^2, which is significantly lower than the value derived by SRBY (median 206 Msun/pc^2) that has been widely adopted by most models of cloud evolution and star formation. This discrepancy arises from both the extrapolation by SRBY of velocity dispersion, size, and CO luminosity to the 1K antenna temperature isophote that likely overestimates the GMC masses and our assumption of constant 13CO abundance over the projected area of each cloud. Owing to the uncertainty of molecular abundances in the envelopes of clouds, the mass surface density of giant molecular clouds could be larger than the values derived from our 13CO measurements. From velocity dispersions derived from the 13CO data, we find that the coefficient of the cloud structure functions, vo=sigma_v/R^{1/2}, is not constant, as required to satisfy Larson's scaling relationships, but rather systematically varies with the surface density of the cloud as Sigma^{0.5} as expected for clouds in self-gravitational equlibrium.Comment: Accepted by ApJ. Newest version includes modifications from the refere

The Olympics, transnational law and legal transplants: the International Olympic Committee, ambush marketing and ticket touting

This paper concerns the origination, development and emergence of what might be termed ‘Olympic law’. This has an impact across borders and with transnational effect. It examines the unique process of creation of these laws, laws created by a national legislature to satisfy the commercial demands of a private body, the International Olympic Committee (IOC). It begins by critically locating the IOC and Olympic law and examining Olympic law as a transnational force. Using two case studies, those of ambush marketing and ticket touting, it demonstrates how private entities can be the drivers of specific, self-interested legislation when operating as a transnational organisation from within the global administrative space and notes the potential dangers of such legal transplants

Physical Properties and Galactic Distribution of Molecular Clouds identified in the Galactic Ring Survey

We derive the physical properties of 580 molecular clouds based on their 12CO and 13CO line emission detected in the University of Massachusetts-Stony Brook (UMSB) and Galactic Ring surveys. We provide a range of values of the physical properties of molecular clouds, and find a power-law correlation between their radii and masses, suggesting that the fractal dimension of the ISM is around 2.36. This relation, M = (228 +/- 18) R^{2.36+/-0.04}, allows us to derive masses for an additional 170 GRS molecular clouds not covered by the UMSB survey. We derive the Galactic surface mass density of molecular gas and examine its spatial variations throughout the Galaxy. We find that the azimuthally averaged Galactic surface density of molecular gas peaks between Galactocentric radii of 4 and 5 kpc. Although the Perseus arm is not detected in molecular gas, the Galactic surface density of molecular gas is enhanced along the positions of the Scutum-Crux and Sagittarius arms. This may indicate that molecular clouds form in spiral arms and are disrupted in the inter-arm space. Last, we find that the CO excitation temperature of molecular clouds decreases away from the Galactic center, suggesting a possible decline in the star formation rate with Galactocentric radius. There is a marginally significant enhancement in the CO excitation temperature of molecular clouds at a Galactocentric radius of about 6 kpc, which in the longitude range of the GRS corresponds to the Sagittarius arm. This temperature increase could be associated with massive star formation in the Sagittarius spiral arm

A maximum likelihood QTL analysis reveals common genome regions controlling resistance to Salmonella colonization and carrier-state

<p>Abstract</p> <p>Background</p> <p>The serovars Enteritidis and Typhimurium of the Gram-negative bacterium <it>Salmonella enterica</it> are significant causes of human food poisoning. Fowl carrying these bacteria often show no clinical disease, with detection only established post-mortem. Increased resistance to the carrier state in commercial poultry could be a way to improve food safety by reducing the spread of these bacteria in poultry flocks. Previous studies identified QTLs for both resistance to carrier state and resistance to <it>Salmonella</it> colonization in the same White Leghorn inbred lines. Until now, none of the QTLs identified was common to the two types of resistance. All these analyses were performed using the F2 inbred or backcross option of the QTLExpress software based on linear regression. In the present study, QTL analysis was achieved using Maximum Likelihood with QTLMap software, in order to test the effect of the QTL analysis method on QTL detection. We analyzed the same phenotypic and genotypic data as those used in previous studies, which were collected on 378 animals genotyped with 480 genome-wide SNP markers. To enrich these data, we added eleven SNP markers located within QTLs controlling resistance to colonization and we looked for potential candidate genes co-localizing with QTLs.</p> <p>Results</p> <p>In our case the QTL analysis method had an important impact on QTL detection. We were able to identify new genomic regions controlling resistance to carrier-state, in particular by testing the existence of two segregating QTLs. But some of the previously identified QTLs were not confirmed. Interestingly, two QTLs were detected on chromosomes 2 and 3, close to the locations of the major QTLs controlling resistance to colonization and to candidate genes involved in the immune response identified in other, independent studies.</p> <p>Conclusions</p> <p>Due to the lack of stability of the QTLs detected, we suggest that interesting regions for further studies are those that were identified in several independent studies, which is the case of the QTL regions on chromosomes 2 and 3, involved in resistance to both <it>Salmonella</it> colonization and carrier state. These observations provide evidence of common genes controlling <it>S.</it> Typhimurium colonization and <it>S</it>. Enteritidis carrier-state in chickens.</p

Capabilities of GPT-4 in ophthalmology: an analysis of model entropy and progress towards human-level medical question answering

Background: Evidence on the performance of Generative Pre-trained Transformer 4 (GPT-4), a large language model (LLM), in the ophthalmology question-answering domain is needed. // Methods: We tested GPT-4 on two 260-question multiple choice question sets from the Basic and Clinical Science Course (BCSC) Self-Assessment Program and the OphthoQuestions question banks. We compared the accuracy of GPT-4 models with varying temperatures (creativity setting) and evaluated their responses in a subset of questions. We also compared the best-performing GPT-4 model to GPT-3.5 and to historical human performance. // Results: GPT-4–0.3 (GPT-4 with a temperature of 0.3) achieved the highest accuracy among GPT-4 models, with 75.8% on the BCSC set and 70.0% on the OphthoQuestions set. The combined accuracy was 72.9%, which represents an 18.3% raw improvement in accuracy compared with GPT-3.5 (p<0.001). Human graders preferred responses from models with a temperature higher than 0 (more creative). Exam section, question difficulty and cognitive level were all predictive of GPT-4-0.3 answer accuracy. GPT-4-0.3’s performance was numerically superior to human performance on the BCSC (75.8% vs 73.3%) and OphthoQuestions (70.0% vs 63.0%), but the difference was not statistically significant (p=0.55 and p=0.09). // Conclusion: GPT-4, an LLM trained on non-ophthalmology-specific data, performs significantly better than its predecessor on simulated ophthalmology board-style exams. Remarkably, its performance tended to be superior to historical human performance, but that difference was not statistically significant in our study

BMI, All-Cause and Cause-Specific Mortality in Chinese Singaporean Men and Women: The Singapore Chinese Health Study

Background: The optimal range of relative weight for morbidity and mortality in Asian populations is an important question in need of more thorough investigation, especially as obesity rates increase. We aimed to examine the association between body mass index (BMI), all cause and cause-specific mortality to determine the optimal range of BMI in relation to mortality in Chinese men and women in Singapore. Methodology/Principal Findings: We analyzed data from a prospective cohort study of 51,251 middle-aged or older (45– 74) Chinese men and women in the Singapore Chinese Health Study. Participants were enrolled and data on body weight and covariates were collected in 1993–1998 and participants were followed through 2008. The analysis accounted for potential methodological issues through stratification on smoking and age, thorough adjustment of demographic and lifestyle confounders and exclusion of deaths early in the follow-up. Conclusions/Significance: Increased risk of mortality was apparent in underweight (,18.5) and obese BMI categories ($27.5) independent of age and smoking. Regardless of age or BMI, smoking considerably increased the rate of mortality and modified the association between BMI and mortality. The most favorable range of BMI for mortality rates and risk in non-smoking persons below age 65 was 18.5–21.4 kg/m 2, and for non-smoking persons aged 65 and above was 21.5