Heavy Quark Potential in a static and strong homogeneous magnetic field

We have investigated the properties of quarkonia in a thermal QCD medium in the background of strong magnetic field. For that purpose, we employ the Schwinger proper-time quark propagator in the lowest Landau level to calculate the one-loop gluon self-energy, which in the sequel gives the the effective gluon propagator. As an artifact of strong magnetic field approximation ($eB>>T^2$ and $eB>>m^2$), the Debye mass for massless flavors is found to depend only on the magnetic field which is the dominant scale in comparison to the scales prevalent in the thermal medium. However, for physical quark masses, it depends on both magnetic field and temperature in a low temperature and high magnetic field but the temperature dependence is very meagre and becomes independent of temperature beyond a certain temperature and magnetic field. With the above mentioned ingredients, the potential between heavy quark ($Q$) and anti-quark ($\bar Q$) is obtained in a hot QCD medium in the presence of strong magnetic field by correcting both short and long range components of the potential in real-time formalism. It is found that the long range part of the quarkonium potential is affected much more by magnetic field as compared to the short range part. This observation facilitates us to estimate the magnetic field beyond which the potential will be too weak to bind $Q\bar Q$ together. For example, the $J/\psi$ is dissociated at $eB \sim$ 10 $m_\pi^2$ and $\Upsilon$ is dissociated at $eB \sim$ 100 $m_\pi^2$ whereas its excited states, $\psi^\prime$ and $\Upsilon^\prime$ are dissociated at smaller magnetic field $eB= m_\pi^2$, $13 m_\pi^2$, respectively.Comment: 20 pages, 5 figure

Resistance to thyroid hormone due to defective thyroid receptor alpha.

Thyroid hormones act via nuclear receptors (TRα1, TRβ1, TRβ2) with differing tissue distribution; the role of α2 protein, derived from the same gene locus as TRα1, is unclear. Resistance to thyroid hormone alpha (RTHα) is characterised by tissue-specific hypothyroidism associated with near-normal thyroid function tests. Clinical features include dysmorphic facies, skeletal dysplasia (macrocephaly, epiphyseal dysgenesis), growth retardation, constipation, dyspraxia and intellectual deficit. Biochemical abnormalities include low/low-normal T4 and high/high-normal T3 concentrations, a subnormal T4/T3 ratio, variably reduced reverse T3, raised muscle creatine kinase and mild anaemia. The disorder is mediated by heterozygous, loss-of-function, mutations involving either TRα1 alone or both TRα1 and α2, with no discernible phenotype attributable to defective α2. Whole exome sequencing and diagnostic biomarkers may enable greater ascertainment of RTHα, which is important as thyroxine therapy reverses some metabolic abnormalities and improves growth, constipation, dyspraxia and wellbeing. The genetic and phenotypic heterogeneity of RTHα and its optimal management remain to be elucidated.Our research is supported by the Wellcome Trust (095564/Z/11/Z to KC), the National Institute for Health Research Cambridge Biomedical Research Centre and the British Thyroid Foundation (CM).This is the final version of the article. It first appeared from Elsevier via http://dx.doi.org/10.1016/j.beem.2015.07.00

Human Disorders Affecting the Selenocysteine Incorporation Pathway Cause Systemic Selenoprotein Deficiency.

Significance: Generalized selenoprotein deficiency has been associated with mutations in SECISBP2, SEPSECS, and TRU-TCA1-1, 3 factors that are crucial for incorporation of the amino acid selenocysteine (Sec) into at least 25 human selenoproteins. SECISBP2 and TRU-TCA1-1 defects are characterized by a multisystem phenotype due to deficiencies of antioxidant and tissue-specific selenoproteins, together with abnormal thyroid hormone levels reflecting impaired hormone metabolism by deiodinase selenoenzymes. SEPSECS mutations are associated with a predominantly neurological phenotype with progressive cerebello-cerebral atrophy. Recent Advances: The recent identification of individuals with defects in genes encoding components of the selenocysteine insertion pathway has delineated complex and multisystem disorders, reflecting a lack of selenoproteins in specific tissues, oxidative damage due to lack of oxidoreductase-active selenoproteins and other pathways whose nature is unclear. Critical Issues: Abnormal thyroid hormone metabolism in patients can be corrected by triiodothyronine (T3) treatment. No specific therapies for other phenotypes (muscular dystrophy, male infertility, hearing loss, neurodegeneration) exist as yet, but their severity often requires supportive medical intervention. Future Directions: These disorders provide unique insights into the role of selenoproteins in humans. The long-term consequences of reduced cellular antioxidant capacity remain unknown, and future surveillance of patients may reveal time-dependent phenotypes (e.g., neoplasia, aging) or consequences of deficiency of selenoproteins whose function remains to be elucidated. The role of antioxidant therapies requires evaluation. Antioxid. Redox Signal. 33, 481-497.NIHR Cambridge Biomedical Research Centr

Finite Time Bounds for Stochastic Bounded Confidence Dynamics

In this era of fast and large-scale opinion formation, a mathematical understanding of opinion evolution, a.k.a. opinion dynamics, acquires importance. Linear graph-based dynamics and bounded confidence dynamics are the two popular models for opinion dynamics in social networks. Stochastic bounded confidence (SBC) opinion dynamics was proposed as a general framework that incorporates both these dynamics as special cases and also captures the inherent stochasticity and noise (errors) in real-life social exchanges. Although SBC dynamics is quite general and realistic, its analysis is more challenging. This is because SBC dynamics is nonlinear and stochastic, and belongs to the class of Markov processes that have asymptotically zero drift and unbounded jumps. The asymptotic behavior of SBC dynamics was characterized in prior works. However, they do not shed light on its finite-time behavior, which is often of interest in practice. We take a stride in this direction by analyzing the finite-time behavior of a two-agent system and a bistar graph, which are crucial to the understanding of general multi-agent dynamics. In particular, we show that the opinion difference between the two agents is well-concentrated around zero under the conditions that lead to asymptotic stability of the SBC dynamics.Comment: A preliminary version of this paper appeared in the proceedings of COMmunication Systems & NETworkS (COMSNETS) 2022. arXiv admin note: substantial text overlap with arXiv:2112.0437

Origin of Large Dielectric Constant with Large Remnant Polarization and Evidence of Magnetoelectric Coupling in Multiferroic La modified BiFeO3-PbTiO3 Solid Solution

The presence of superlattice reflections and detailed analyses of the powder neutron and x-ray diffraction data reveal that La rich (BF$_{0.50}$-LF$_{0.50}$)$_{0.50}$-(PT)$_{0.50}$ (BF-LF-PT) has ferroelectric rhombohedral crystal structure with space group \textit{$R3c$} at ambient conditions. The temperature dependence of lattice parameters, tilt angle, calculated polarization $(P_{s})$, volume, and integrated intensity of superlattice and magnetic reflections show an anomaly around 170 K. Impedance spectroscopy, dielectric and ac conductivity measurements were performed in temperature range $473K \leq T \leq 573K$ to probe the origin of large remnant polarization and frequency dependent broad transitions with large dielectric constant near $T_c^{FE}$. Results of impedance spectroscopy measurements clearly show contributions of both grain and grain boundaries throughout the frequency range ($10^{3}$ Hz$\leq f\leq 10^{7}$ Hz). It could be concluded that the grain boundaries are more resistive and capacitive as compared to the grains, resulting in inhomogeneities in the sample causing broad frequency dependent dielectric anomalies. Enhancement in dielectric constant and remnant polarization values are possibly due to space charge polarization caused by piling of charges at the interface of grains and grain boundaries. The imaginary parts of dielectric constant ($\epsilon^{\prime\prime}$) Vs frequency data were fitted using Maxwell-Wagner model at $T_c^{FE}(\sim 523$K) and model fits very well with the data up to $10^{5}$ Hz. Magnetodielectric measurements prove that the sample starts exhibiting magnetoelectric coupling at $\sim 170$ K, which is also validated by neutron diffraction data.Comment: 20 pages, 10 figure