Charles University in Prague

About: Charles University in Prague is a education organization based out in Prague, Czechia. It is known for research contribution in the topics: Population & Large Hadron Collider. The organization has 32392 authors who have published 74435 publications receiving 1804208 citations.

Topological cell clustering in the ATLAS calorimeters and its performance in LHC Run 1

Abstract: The reconstruction of the signal from hadrons and jets emerging from the proton–proton collisions at the Large Hadron Collider (LHC) and entering the ATLAS calorimeters is based on a three-dimensional topological clustering of individual calorimeter cell signals. The cluster formation follows cell signal-significance patterns generated by electromagnetic and hadronic showers. In this, the clustering algorithm implicitly performs a topological noise suppression by removing cells with insignificant signals which are not in close proximity to cells with significant signals. The resulting topological cell clusters have shape and location information, which is exploited to apply a local energy calibration and corrections depending on the nature of the cluster. Topological cell clustering is established as a well-performing calorimeter signal definition for jet and missing transverse momentum reconstruction in ATLAS.

The role of adipose tissue immune cells in obesity and low-grade inflammation

Abstract: Adipose tissue (AT) lies at the crossroad of nutrition, metabolism, and immunity; AT inflammation was proposed as a central mechanism connecting obesity with its metabolic and vascular complications. Resident immune cells constitute the second largest AT cellular component after adipocytes and as such play important roles in the maintenance of AT homeostasis. Obesity-induced changes in their number and activity result in the activation of local and later systemic inflammatory response, marking the transition from simple adiposity to diseases such as type 2 diabetes mellitus, arterial hypertension, and ischemic heart disease. This review has focused on the various subsets of immune cells in AT and their role in the development of AT inflammation and obesity-induced insulin resistance.

Association of human aging with a functional variant of klotho

Abstract: Mice deficient in Klotho gene expression exhibit a syndrome resembling premature human aging. To determine whether variation in the human KLOTHO locus contributes to survival, we applied two newly characterized polymorphic microsatellite markers flanking the gene in a population-based association study. In a cohort chosen for its homogeneity, Bohemian Czechs, we demonstrated significant differences in selected marker allele frequencies between newborn and elderly individuals (P < 0.05). These results precipitated a search for functional variants of klotho. We identified an allele, termed KL-VS, containing six sequence variants in complete linkage disequilibrium, two of which result in amino acid substitutions F352V and C370S. Homozygous elderly individuals were underrepresented in three distinct populations: Bohemian Czechs, Baltimore Caucasians, and Baltimore African-Americans [combined odds ratio (OR) = 2.59, P < 0.0023]. In a transient transfection assay, secreted levels of klotho harboring V352 are reduced 6-fold, whereas extracellular levels of the S370 form are increased 2.9-fold. The V352/S370 double mutant exhibits an intermediate phenotype (1.6-fold increase), providing a rare example of intragenic complementation in cis by human single nucleotide polymorphisms. The remarkable conservation of F352 among homologous proteins suggests that it is functionally important. The corresponding substitution, F289V, in the closest human klotho paralog with a known substrate, cBGL1, completely eliminates its ability to cleave p-nitrophenyl-β-d-glucoside. These results suggest that the KL-VS allele influences the trafficking and catalytic activity of klotho, and that variation in klotho function contributes to heterogeneity in the onset and severity of human age-related phenotypes.

Measuring the Frequency Dynamics of Financial Connectedness and Systemic Risk

Abstract: We propose a new framework for measuring connectedness among financial variables that arise due to heterogeneous frequency responses to shocks. To estimate connectedness in short-, medium-, and long-term financial cycles, we introduce a framework based on the spectral representation of variance decompositions. In an empirical application, we document the rich time-frequency dynamics of volatility connectedness in U.S. financial institutions. Economically, periods in which connectedness is created at high frequencies are periods when stock markets seem to process information rapidly and calmly, and a shock to one asset in the system will have an impact mainly in the short term. When the connectedness is created at lower frequencies, it suggests that shocks are persistent and are being transmitted for longer periods.