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BL Lacs are one subclass of blazars with highly energetic γ -ray emission, which is strongly boosted by a relativistic beaming effect. The latest catalogue of the 10 years of Fermi/LAT data (Abdollahi et al. 2020) and the γ -ray Doppler factors in Pei et al. (2020) provide us with a large BL Lac sample to study their jet emission morphologies and intrinsic properties. In this paper, we collected a sample of 294 Fermi BL Lacs and probed the correlations between the γ -ray emissions and luminosity distances. Our analyses give following conclusions: (1) the observed γ -ray emissions are really boosted by the γ -ray Doppler factor, and the intrinsic γ -ray emissions are closely correlated with luminosity distances. (2) the morphology of jet emissions for HBLs may be continuous, while that for IBLs may be the case of a moving sphere in the γ -ray bands. [ABSTRACT FROM AUTHOR]

Searching for as yet undetected γ -ray sources is one of the main stated goals of the Fermi Large Area Telescope Collaboration. In this paper, we explore the capability of a filtering method based on a finite mixture of von Mises–Fisher distributions. The proposed procedure is specifically designed to handle data with support on the unit sphere. The assumption of a parametric model for each high energy emitting source allows us to derive an explicit expression for both the direction of the sources and their angular resolutions. The corresponding measures are based on the directional mean and the quantiles of the single mixture components. Sound criteria of model selection can provide an automatic way to determine the number of detected sources. Additionally, a likelihood-ratio test is developed to evaluate their significance. The procedure is tested on simulated data sets of photon emissions from high energy sources within the energy range [ 10 − 1 , 000 ] GeV . A real data example consisting of a sample of the Fermi LAT data collected over a period of about 7.2 years within the energy range [ 10 − 1 , 000 ] GeV , in a subregion of the γ -ray sky, is furthermore provided. [ABSTRACT FROM AUTHOR]

The most identified sources observed by Fermi/LAT are blazars, based on which we can investigate the emission mechanisms and beaming effect in the γ-ray bands for blazars. Here, we used the compiled around 450 Fermi blazars with the available X-ray observations to estimate their Doppler factors and compared them with the integral γ-ray luminosity in the range of 1-100 GeV. It is interesting that the integral γ-ray luminosity is closely correlated with the estimated Doppler factor, νγLνγ = (2.95 ± 0.09)log δ + 43.59 ± 0.08 for the whole sample. When the dependence of the correlation between them and the X-ray luminosity is removed, the correlation is still strong, which suggests that the γ-ray emissions are strongly beamed. [ABSTRACT FROM AUTHOR]

Background:Although vitamin D deficiency has been noted in cross-sectional studies of chronic liver disease and laboratory studies suggest possible benefits of vitamin D in preventing liver cancer, little epidemiologic data are available.Methods:We performed a nested case-control study in the Linxian Nutrition Intervention Trials on participants developing incident liver cancer or dying from chronic liver disease over 22 years of follow-up. Baseline serum 25(OH) vitamin D was measured for 226 incident liver cancer cases, 282 chronic liver disease deaths and 1063 age-, sex- and trial-matched controls. Unconditional logistical regression models were used to estimate odds ratios (ORs) and 95% confidence intervals (CIs).Results:The median serum vitamin D level in controls was low (20 nmol l-1). Compared with the lowest quartile, subjects in the fourth quartile had lower risk of chronic liver disease death (OR=0.34, 95% CI=0.21-0.55). For liver cancer incidence, risk estimates were below one, but were not statistically significant. Associations, however, were significant among participants with higher serum calcium levels (Q4 vs Q1, OR=0.43, 95% CI=0.21-0.89). Results for chronic liver disease did not vary by serum calcium level.Conclusion:In a low vitamin D population, higher serum 25(OH) vitamin D concentrations were associated with significantly lower risk of chronic liver disease deaths, and among those with higher serum calcium, incident liver cancer. Our results suggest a possible protective role for vitamin D in these diseases. [ABSTRACT FROM AUTHOR]

By employing the notion of exceptional family of elements, we establish some existence results for generalized variational inequality problems in reflexive Banach spaces provided that the mapping is upper sign-continuous. We show that the nonexistence of an exceptional family of elements is a necessary condition for the solvability of the dual variational inequality. For quasimonotone variational inequalities, we present some sufficient conditions for the existence of strong solutions. For the pseudomonotone case, the nonexistence of an exceptional family of elements is proved to be an equivalent characterization of the problem having strong solutions. Furthermore, we establish several equivalent conditions for the solvability for the pseudomonotone case. As a byproduct, a quasimonotone generalized variational inequality is proved to have a strong solution if it is strictly feasible. Moreover, for the pseudomonotone case, the strong solution set is nonempty and bounded if it is strictly feasible. [ABSTRACT FROM AUTHOR]

In a cohort of 29,584 residents of Linxian, China, followed from 1985 to 2001, we conducted a case-cohort study of the magnitude of the association of Helicobacter pylori seropositivity with cancer risk in a random sample of 300 oesophageal squamous cell carcinomas, 600 gastric cardia adenocarcinomas, all 363 diagnosed gastric non-cardia adenocarcinomas, and a random sample of the entire cohort (N=1050). Baseline serum was evaluated for IgG antibodies to whole-cell and CagA H. pylori antigens by enzyme-linked immunosorbent assay. Risks of both gastric cardia and non-cardia cancers were increased in individuals exposed to H. pylori (Hazard ratios (HRs) and 95% confidence intervals=1.64; 1.26-2.14, and 1.60; 1.15-2.21, respectively), whereas risk of oesophageal squamous cell cancer was not affected (1.17; 0.88-1.57). For both cardia and non-cardia cancers, HRs were higher in younger individuals. With longer time between serum collection to cancer diagnosis, associations became stronger for cardia cancers but weaker for non-cardia cancers. CagA positivity did not modify these associations. The associations between H. pylori exposure and gastric cardia and non-cardia adenocarcinoma development were equally strong, in contrast to Western countries, perhaps due to the absence of Barrett's oesophagus and oesophageal adenocarcinomas in Linxian, making all cardia tumours of gastric origin, rather than a mixture of gastric and oesophageal malignancies. [ABSTRACT FROM AUTHOR]

In this paper, multiwavelength chromatic luminosity at radio (logLR), optical (logLO), X-ray (logLX), and γ-rays (logLγ) for a sample of 442 Fermi blazars with known redshifts are collected from Fan et al. (2016), to study the correlations between the γ-rays and the low-energy bands using a multiple linear regression analysis. In this way, we can see which band is more important for the γ-ray emissions. Mutual correlation analysis is also used to discuss the correlations between the γ-ray and the low energy bands for the whole sample and subclasses. We come to following conclusions: The multiple linear correlation indicates that the γ-rays are correlated with the radio, optical and the X-ray emissions for the whole sample and the subclasses of flat spectrum radio quasars (FSRQs) and BL Lac objects (BL Lacs), the correlation between the γ-rays and the radio emissions is the strongest one.For BL Lacs, the optical emissions are more important than the X-rays for the γ-rays, while the X-ray emissions are more important than optical ones in FSRQs.The γ-ray emissions in HBL are from an synchrotron self-Compton, while those in FSRQs may be from external Compton and synchrotron self-Compton as well. [ABSTRACT FROM AUTHOR]