Search for Exotic Strange Quark Matter in High Energy Nuclear Reactions

We report on a search for metastable positively and negatively charged states of strange quark matter in Au+Pb reactions at 11.6 A GeV/c in experiment E864. We have sampled approximately six billion 10% most central Au+Pb interactions and have observed no strangelet states (baryon number A < 100 droplets of strange quark matter). We thus set upper limits on the production of these exotic states at the level of 1-6 x 10^{-8} per central collision. These limits are the best and most model independent for this colliding system. We discuss the implications of our results on strangelet production mechanisms, and also on the stability question of strange quark matter.Comment: 21 pages, 9 figures, to be published in Nuclear Physics A (Carl Dover memorial edition

Attention-dependent modulation of cortical taste circuits revealed by granger causality with signal-dependent noise

We show, for the first time, that in cortical areas, for example the insular, orbitofrontal, and lateral prefrontal cortex, there is signal-dependent noise in the fMRI blood-oxygen level dependent (BOLD) time series, with the variance of the noise increasing approximately linearly with the square of the signal. Classical Granger causal models are based on autoregressive models with time invariant covariance structure, and thus do not take this signal-dependent noise into account. To address this limitation, here we describe a Granger causal model with signal-dependent noise, and a novel, likelihood ratio test for causal inferences. We apply this approach to the data from an fMRI study to investigate the source of the top-down attentional control of taste intensity and taste pleasantness processing. The Granger causality with signal-dependent noise analysis reveals effects not identified by classical Granger causal analysis. In particular, there is a top-down effect from the posterior lateral prefrontal cortex to the insular taste cortex during attention to intensity but not to pleasantness, and there is a top-down effect from the anterior and posterior lateral prefrontal cortex to the orbitofrontal cortex during attention to pleasantness but not to intensity. In addition, there is stronger forward effective connectivity from the insular taste cortex to the orbitofrontal cortex during attention to pleasantness than during attention to intensity. These findings indicate the importance of explicitly modeling signal-dependent noise in functional neuroimaging, and reveal some of the processes involved in a biased activation theory of selective attention

Identification of monetary policy in SVAR models: A data-oriented perspective

In the literature using short-run timing restrictions to identify monetary policy shocks in vector-auto-regressions (VAR) there is a debate on whether (i) contemporaneous real activity and prices or (ii) only data typically observed with high frequency should be assumed to be in the information set of the central bank when the interest rate decision is taken. This paper applies graphical modeling theory, a data-based tool, in a small-scale VAR of the US economy to shed light on this issue. Results corroborate the second type of assumption

Toll-like receptor 7 rs179008/Gln11Leu gene variants in chronic hepatitis C virus infection

International audienceHepatitis C virus (HCV) infection affects an estimated 3% of the world's population. The natural outcome of infection and the natural course of disease are highly variable. Sensing of viral single-stranded RNA (ssRNA) by Toll-like receptor 7 (TLR7) is likely involved in early pathogen detection and host response to viral infections. This study analyzed epidemiological and clinical data from 136 patients with HCV infection with regard to rs179008/Gln11Leu, a non-synonymous polymorphism within exon 3 of the X-linked TLR7 gene, the variant allele of which is suggested to code for a functionally impaired protein. Allele-specific transcript quantification (ASTQ) analyses in heterozygous females revealed individual skewed mosaicism in peripheral blood mononuclear cells (PBMCs). Thus, analyses were restricted to homo- and hemizygous individuals. Among the clinical and histological parameters studied, the variant allele T was found to be solely associated with the presence of portal lymphoid aggregates. Whereas hepatic viral load and expression of genes known to be induced in chronic HCV infection were not found to differ in patients with wildtype or variant TLR7 rs179008 genotype, significant lower gene expression of interleukin-29 (IL-29)/lambda1 interferon (IFN-λ1) and both of its receptor subunits was found for T homo- and hemizygous patients. Irrespective of the minor differences in disease phenotype including hepatic viral load, natural and alpha interferon (IFN-α)-mediated outcome of infection, and disease activity and progression, the significant differences in hepatic IL-29/IFN-λ1 and IFN-λ receptor gene expression between TLR7 rs179008 T and A allele patients might have implications for responsiveness to future IFN-λ-based approaches

Search for Strange Quark Matter Produced in Relativistic Heavy Ion Collisions

We present the final results from Experiment 864 of a search for charged and neutral strange quark matter produced in interactions of 11.5 GeV/c per nucleon Au beams with Pt or Pb targets. Searches were made for strange quark matter with A>4. Approximately 30 billion 10% most central collisions were sampled and no strangelet states with A<100 were observed. We find 90% confidence level upper limits of approximately 10^{-8} per central collision for both charged and neutral strangelets. These limits are for strangelets with proper lifetimes greater than 50 ns. Also limits for H^{0}-d and pineut production are given. The above limits are compared with the predictions of various models. The yields of light nuclei from coalescence are measured and a penalty factor for the addition of one nucleon to the coalescing nucleus is determined. This is useful in gauging the significance of our upper limits and also in planning future searches for strange quark matter.Comment: 35 pages, 18 figures, submitted to Phys. Rev.

Chitosan Modification of Adenovirus to Modify Transfection Efficiency in Bovine Corneal Epithelial Cells

BACKGROUND: The purpose of this study is to modulate the transfection efficiency of adenovirus (Ad) on the cornea by the covalent attachment of chitosan on adenoviral capsids via a thioether linkage between chitosan modified with 2-iminothiolane and Ad cross-linked with N-[gamma-maleimidobutyryloxy]succinimide ester (GMBS). METHODOLOGY/PRINCIPAL FINDINGS: Modified Ad was obtained by reaction with the heterobifunctional crosslinking reagent, GMBS, producing maleimide-modified Ad (Ad-GMBS). Then, the chitosan-SH was conjugated to Ad-GMBS via a thioether bond at different ratios of Ad to GMBS to chitosan-SH. The sizes and zeta potentials of unmodified Ad and chitosan-modified Ads were measured, and the morphologies of the virus particles were observed under transmission electron microscope. Primary cultures of bovine corneal epithelial cells were transfected with Ads and chitosan-modified Ads in the absence or presence of anti-adenovirus antibodies. Chitosan modification did not significantly change the particle size of Ad, but the surface charge of Ad increased significantly from -24.3 mV to nearly neutral. Furthermore, primary cultures of bovine corneal epithelial cells were transfected with Ad or chitosan-modified Ad in the absence or presence of anti-Ad antibodies. The transfection efficiency was attenuated gradually with increasing amounts of GMBS. However, incorporation of chitosan partly restored transfection activity and rendered the modified antibody resistant to antibody neutralization. CONCLUSIONS/SIGNIFICANCE: Chitosan can provide a platform for chemical modification of Ad, which offers potential for further in vivo applications

The enhanced X-ray Timing and Polarimetry mission – eXTP: an update on its scientific cases, mission profile and development status

The enhanced X-ray Timing and Polarimetry mission (eXTP) is a flagship observatory for X-ray timing, spectroscopy and polarimetry developed by an International Consortium. Thanks to its very large collecting area, good spectral resolution and unprecedented polarimetry capabilities, eXTP will explore the properties of matter and the propagation of light in the most extreme conditions found in the Universe. eXTP will, in addition, be a powerful X-ray observatory. The mission will continuously monitor the X-ray sky, and will enable multiwavelength and multi-messenger studies. The mission is currently in phase B, which will be completed in the middle of 2022

Co-ordinated Role of TLR3, RIG-I and MDA5 in the Innate Response to Rhinovirus in Bronchial Epithelium

The relative roles of the endosomal TLR3/7/8 versus the intracellular RNA helicases RIG-I and MDA5 in viral infection is much debated. We investigated the roles of each pattern recognition receptor in rhinovirus infection using primary bronchial epithelial cells. TLR3 was constitutively expressed; however, RIG-I and MDA5 were inducible by 8–12 h following rhinovirus infection. Bronchial epithelial tissue from normal volunteers challenged with rhinovirus in vivo exhibited low levels of RIG-I and MDA5 that were increased at day 4 post infection. Inhibition of TLR3, RIG-I and MDA5 by siRNA reduced innate cytokine mRNA, and increased rhinovirus replication. Inhibition of TLR3 and TRIF using siRNA reduced rhinovirus induced RNA helicases. Furthermore, IFNAR1 deficient mice exhibited RIG-I and MDA5 induction early during RV1B infection in an interferon independent manner. Hence anti-viral defense within bronchial epithelium requires co-ordinated recognition of rhinovirus infection, initially via TLR3/TRIF and later via inducible RNA helicases

The underpinning biology relating to multiple sclerosis disease modifying treatments during the COVID-19 pandemic

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