Anisotropic generalization of well-known solutions describing relativistic self-gravitating fluid systems: An algorithm

We present an algorithm to generalize a plethora of well-known solutions to Einstein field equations describing spherically symmetric relativistic fluid spheres by relaxing the pressure isotropy condition on the system. By suitably fixing the model parameters in our formulation, we generate closed-form solutions which may be treated as anisotropic generalization of a large class of solutions describing isotropic fluid spheres. From the resultant solutions, a particular solution is taken up to show its physical acceptability. Making use of the current estimate of mass and radius of a known pulsar, the effects of anisotropic stress on the gross physical behaviour of a relativistic compact star is also highlighted.Comment: To appear in Eur. Phys. J.

Endocrinologic, neurologic, and visual morbidity after treatment for craniopharyngioma

Craniopharyngiomas are locally aggressive tumors which typically are focused in the sellar and suprasellar region near a number of critical neural and vascular structures mediating endocrinologic, behavioral, and visual functions. The present study aims to summarize and compare the published literature regarding morbidity resulting from treatment of craniopharyngioma. We performed a comprehensive search of the published English language literature to identify studies publishing outcome data of patients undergoing surgery for craniopharyngioma. Comparisons of the rates of endocrine, vascular, neurological, and visual complications were performed using Pearson’s chi-squared test, and covariates of interest were fitted into a multivariate logistic regression model. In our data set, 540 patients underwent surgical resection of their tumor. 138 patients received biopsy alone followed by some form of radiotherapy. Mean overall follow-up for all patients in these studies was 54 ± 1.8 months. The overall rate of new endocrinopathy for all patients undergoing surgical resection of their mass was 37% (95% CI = 33–41). Patients receiving GTR had over 2.5 times the rate of developing at least one endocrinopathy compared to patients receiving STR alone or STR + XRT (52 vs. 19 vs. 20%, χ2P < 0.00001). On multivariate analysis, GTR conferred a significant increase in the risk of endocrinopathy compared to STR + XRT (OR = 3.45, 95% CI = 2.05–5.81, P < 0.00001), after controlling for study size and the presence of significant hypothalamic involvement. There was a statistical trend towards worse visual outcomes in patients receiving XRT after STR compared to GTR or STR alone (GTR = 3.5% vs. STR 2.1% vs. STR + XRT 6.4%, P = 0.11). Given the difficulty in obtaining class 1 data regarding the treatment of this tumor, this study can serve as an estimate of expected outcomes for these patients, and guide decision making until these data are available

General relativistic model for mixed fluid sphere with equation of state

Abstract We generate a general frame work to solve the Einstein system with an equation of state that describe static spherically symmetric anisotropic matter distribution in terms of a generating function. It is examined for a Van der Waals type equation of state with a physically reasonable form of generating function. The model satisfies all the required major physical properties of a realistic star. It is shown to be stable in the low-density regime that may represent a liquid–gas mixed fluid sphere

Anisotropic generalization of isotropic models via hypergeometric equation

We study Einstein’s field equations to describe static spherically symmetric relativistic compact objects with anisotropic matter distribution, and generate two classes of exact solutions by choosing a generalized form for one of the gravitational potentials and a particular form for the measure of anisotropy. This is achieved by transforming the Einstein’s field equation to a hypergeometric equation. The generated models generalize the isotropic models of Durgapal–Bannerji, Tikekar and Vaidya–Tikekar. The physical viability of the model is examined and compared with observational results of strange star candidates

EFSUMB 2020 Proposal for a Contrast-Enhanced Ultrasound-Adapted Bosniak Cyst Categorization-Position Statement

The well-established Bosniak renal cyst classification is based on contrast-enhanced computed tomography determining the malignant potential of cystic renal lesions. Ultrasound has not been incorporated into this pathway. However, the development of ultrasound contrast agents coupled with the superior resolution of ultrasound makes it possible to redefine the imaging of cystic renal lesions. In this position statement, an EFSUMB Expert Task Force reviews, analyzes, and describes the accumulated knowledge and limitations and presents the current position on the use of ultrasound contrast agents in the evaluation of cystic renal lesions

A Ca2+-sensor switch for tolerance to elevated salt stress in Arabidopsis

Summary Excessive Na+ in soils inhibits plant growth. Here, we report that Na+ stress triggers primary calcium signals specifically in a cell group within the root differentiation zone, thus forming a “sodium-sensing niche” in Arabidopsis. The amplitude of this primary calcium signal and the speed of the resulting Ca2+ wave dose-dependently increase with rising Na+ concentrations, thus providing quantitative information about the stress intensity encountered. We also delineate a Ca2+-sensing mechanism that measures the stress intensity in order to mount appropriate salt detoxification responses. This is mediated by a Ca2+-sensor-switch mechanism, in which the sensors SOS3/CBL4 and CBL8 are activated by distinct Ca2+-signal amplitudes. Although the SOS3/CBL4-SOS2/CIPK24-SOS1 axis confers basal salt tolerance, the CBL8-SOS2/CIPK24-SOS1 module becomes additionally activated only in response to severe salt stress. Thus, Ca2+-mediated translation of Na+ stress intensity into SOS1 Na+/H+ antiporter activity facilitates fine tuning of the sodium extrusion capacity for optimized salt-stress tolerance