Sr-Nd isotope geochemistry of the early Precambrian sub-alkaline mafic igneous rocks from the southern Bastar craton, Central India

Sr–Nd isotope data are reported for the early Precambrian sub-alkaline mafic igneous rocks of the southern Bastar craton, central India. These mafic rocks are mostly dykes but there are a few volcanic exposures. Field relationships together with the petrological and geochemical characteristics of these mafic dykes divide them into two groups; Meso-Neoarchaean sub-alkaline mafic dykes (BD1) and Paleoproterozoic (1.88 Ga) sub-alkaline mafic dykes (BD2). The mafic volcanics are Neoarchaean in age and have very close geochemical relationships with the BD1 type. The two groups have distinctly different concentrations of high-field strength (HFSE) and rare earth elements (REE). The BD2 dykes have higher concentrations of HFSE and REE than the BD1 dykes and associated volcanics and both groups have very distinctive petrogenetic histories. These rocks display a limited range of initial 143Nd/144Nd but a wide range of apparent initial 87Sr/86Sr. Initial 143Nd/144Nd values in the BD1 dykes and associated volcanics vary between 0.509149 and 0.509466 and in the BD2 dykes the variation is between 0.510303 and 0.510511. All samples have positive εNd values the BD1 dykes and associated volcanics have εNd values between +0.3 and +6.5 and the BD2 dykes between +1.9 to +6.0. Trace element and Nd isotope data do not suggest severe crustal contamination during the emplacement of the studied rocks. The positive εNd values suggest their derivation from a depleted mantle source. Overlapping positive εNd values suggest that a similar mantle source tapped by variable melt fractions at different times was responsible for the genesis of BD1 (and associated volcanics) and BD2 mafic dykes. The Rb–Sr system is susceptible to alteration and resetting during post-magmatic alteration and metamorphism. Many of the samples studied have anomalous apparent initial 87Sr/86Sr suggesting post-magmatic changes of the Rb–Sr system which severely restricts the use of Rb–Sr for petrogenetic interpretation

Binding of thrombin to glycoprotein Ib accelerates the hydrolysis of Par-1 on intact platelets

The activation of human platelets by α-thrombin is mediated at least in part by cleavage of protease-activated G-protein-coupled receptors, PAR-1 and PAR-4. Platelet glycoprotein Ibα also has a high affinity binding site for α-thrombin, and this interaction contributes to platelet activation through a still unknown mechanism. In the present study the hypothesis that GpIbα may contribute to platelet activation by modulating the hydrolysis of PAR-1 on the platelet membrane was investigated. Gel-filtered platelets from normal individuals were stimulated by α-thrombin, and the kinetics of PAR-1 hydrolysis by enzyme was followed with flow cytometry using an anti-PAR-1 monoclonal antibody (SPAN 12) that recognizes only intact PAR-1 molecules. This strategy allowed measurement of the apparentk cat/K m value for thrombin hydrolysis of PAR-1 on intact platelets, which was equal to 1.5 ± 0.1 × 107 m −1sec−1. The hydrolysis rate of PAR-1 by thrombin was measured under conditions in which thrombin binding to GpIb was inhibited by different strategies, with the following results. 1) Elimination of GpIbα on platelet membranes by mocarhagin treatment reduced the k cat/K m value by about 6-fold. 2) A monoclonal anti-GpIb antibody reduced the apparent k cat/K m value by about 5-fold. 3) An oligonucleotide DNA aptamer, HD22, which binds to the thrombin heparin-binding site (HBS) and inhibits thrombin interaction with GpIbα, reduced the apparentk cat/K m value by about 5-fold. 4) Displacement of α-thrombin from the binding site on GpIb using PPACK-thrombin reduced the apparentk cat/K m value by about 5-fold, and 5) mutation at the HBS of thrombin (R98A) caused a 5-fold reduction of the apparentk cat/K m value of PAR-1 hydrolysis. Altogether these results show that thrombin interaction with GpIb enhances the specificity of thrombin cleavage of PAR-1 on intact platelets, suggesting that GpIb may function as a “cofactor” for PAR-1 activation by thrombin

Systems analysis of transcription factor activities in environments with stable and dynamic oxygen concentrations.

Understanding gene regulation requires knowledge of changes in transcription factor (TF) activities. Simultaneous direct measurement of numerous TF activities is currently impossible. Nevertheless, statistical approaches to infer TF activities have yielded non-trivial and verifiable predictions for individual TFs. Here, global statistical modelling identifies changes in TF activities from transcript profiles of Escherichia coli growing in stable (fixed oxygen availabilities) and dynamic (changing oxygen availability) environments. A core oxygen-responsive TF network, supplemented by additional TFs acting under specific conditions, was identified. The activities of the cytoplasmic oxygen-responsive TF, FNR, and the membrane-bound terminal oxidases implied that, even on the scale of the bacterial cell, spatial effects significantly influence oxygen-sensing. Several transcripts exhibited asymmetrical patterns of abundance in aerobic to anaerobic and anaerobic to aerobic transitions. One of these transcripts, ndh, encodes a major component of the aerobic respiratory chain and is regulated by oxygen-responsive TFs ArcA and FNR. Kinetic modelling indicated that ArcA and FNR behaviour could not explain the ndh transcript profile, leading to the identification of another TF, PdhR, as the source of the asymmetry. Thus, this approach illustrates how systematic examination of regulatory responses in stable and dynamic environments yields new mechanistic insights into adaptive processes

Hearts deficient in both Mfn1 and Mfn2 are protected against acute myocardial infarction

Mitochondria alter their shape by undergoing cycles of fusion and fission. Changes in mitochondrial morphology impact on the cellular response to stress, and their interactions with other organelles such as the sarcoplasmic reticulum (SR). Inhibiting mitochondrial fission can protect the heart against acute ischemia/reperfusion (I/R) injury. However, the role of the mitochondrial fusion proteins, Mfn1 and Mfn2, in the response of the adult heart to acute I/R injury is not clear, and is investigated in this study. To determine the effect of combined Mfn1/Mfn2 ablation on the susceptibility to acute myocardial I/R injury, cardiac-specific ablation of both Mfn1 and Mfn2 (DKO) was initiated in mice aged 4-6 weeks, leading to knockout of both these proteins in 8-10-week-old animals. This resulted in fragmented mitochondria (electron microscopy), decreased mitochondrial respiratory function (respirometry), and impaired myocardial contractile function (echocardiography). In DKO mice subjected to in vivo regional myocardial ischemia (30 min) followed by 24 h reperfusion, myocardial infarct size (IS, expressed as a % of the area-at-risk) was reduced by 46% compared with wild-type (WT) hearts. In addition, mitochondria from DKO animals had decreased MPTP opening susceptibility (assessed by Ca(2+)-induced mitochondrial swelling), compared with WT hearts. Mfn2 is a key mediator of mitochondrial/SR tethering, and accordingly, the loss of Mfn2 in DKO hearts reduced the number of interactions measured between these organelles (quantified by proximal ligation assay), attenuated mitochondrial calcium overload (Rhod2 confocal microscopy), and decreased reactive oxygen species production (DCF confocal microscopy) in response to acute I/R injury. No differences in isolated mitochondrial ROS emissions (Amplex Red) were detected in response to Ca(2+) and Antimycin A, further implicating disruption of mitochondria/SR tethering as the protective mechanism. In summary, despite apparent mitochondrial dysfunction, hearts deficient in both Mfn1 and Mfn2 are protected against acute myocardial infarction due to impaired mitochondria/SR tethering

A Universal Lifetime Distribution for Multi-Species Systems

Lifetime distributions of social entities, such as enterprises, products, and media contents, are one of the fundamental statistics characterizing the social dynamics. To investigate the lifetime distribution of mutually interacting systems, simple models having a rule for additions and deletions of entities are investigated. We found a quite universal lifetime distribution for various kinds of inter-entity interactions, and it is well fitted by a stretched-exponential function with an exponent close to 1/2. We propose a "modified Red-Queen" hypothesis to explain this distribution. We also review empirical studies on the lifetime distribution of social entities, and discussed the applicability of the model.Comment: 10 pages, 6 figures, Proceedings of Social Modeling and Simulations + Econophysics Colloquium 201

Quantum Key Distribution using Multilevel Encoding: Security Analysis

We present security proofs for a protocol for Quantum Key Distribution (QKD) based on encoding in finite high-dimensional Hilbert spaces. This protocol is an extension of Bennett's and Brassard's basic protocol from two bases, two state encoding to a multi bases, multi state encoding. We analyze the mutual information between the legitimate parties and the eavesdropper, and the error rate, as function of the dimension of the Hilbert space, while considering optimal incoherent and coherent eavesdropping attacks. We obtain the upper limit for the legitimate party error rate to ensure unconditional security when the eavesdropper uses incoherent and coherent eavesdropping strategies. We have also consider realistic noise caused by detector's noise.Comment: 8 pages, 3 figures, REVTe

A Sparse Stress Model

Force-directed layout methods constitute the most common approach to draw general graphs. Among them, stress minimization produces layouts of comparatively high quality but also imposes comparatively high computational demands. We propose a speed-up method based on the aggregation of terms in the objective function. It is akin to aggregate repulsion from far-away nodes during spring embedding but transfers the idea from the layout space into a preprocessing phase. An initial experimental study informs a method to select representatives, and subsequent more extensive experiments indicate that our method yields better approximations of minimum-stress layouts in less time than related methods.Comment: Appears in the Proceedings of the 24th International Symposium on Graph Drawing and Network Visualization (GD 2016

The smart grid as commons: exploring alternatives to infrastructure financialisation

This paper explores a tension between financialisation of electricity infrastructures and efforts to bring critical urban systems into common ownership. Focusing on the emerging landscape of electricity regulation and e-mobility in the United Kingdom (UK), it examines how electricity grid ownership has become financialised, and why the economic assumptions that enabled this financialisation are being called into question. New technologies, such as smart electricity meters and electric vehicles, provide cities with new tools to tackle poor air quality and greenhouse gas emissions. Electricity grids are key enabling infrastructures but the companies that run them do not get rewarded for improving air quality or tackling climate change. UK government regulation of electricity grids both enables financialisation and forecloses opportunities to manage the infrastructure for wider environmental and public benefit. Nonetheless, the addition of smart devices to this network - the ‘smart grid’ – opens up an opportunity for common ownership of the infrastructure. Transforming the smart grid into commons necessitates deep structural reform to the entire architecture of infrastructure regulation in the UK

Contraceptive use, prevalence and predictors of pregnancy planning among female sex workers in Uganda: a cross sectional study

BACKGROUND: Unintended pregnancies are associated with negative consequences to both mother and baby. Female Sex Workers (FSWs) are at high risk of unintended/unplanned pregnancies. However, prevalence of pregnancy planning and its predictors among FSWs has not been comprehensively investigated. This study was designed to determine contraceptive use, the prevalence, and predictors of pregnancy planning among FSWs in Uganda. METHODS: In this cross-sectional study, 819 FSWs attending most at risk populations initiative (MARPI) clinics were recruited using systematic sampling and interviewed with a pretested questionnaire that included collection of data on pregnancy intention using the London Measure of Unplanned Pregnancy (LMUP). Data were analysed using STATA version 14.0. Multinomial logistic regression model was used to identify predictors of pregnancy planning, RESULTS: Of the 819 study participants, only 90 (11.0%) had planned pregnancies. Overall, 462 (56.4%) were hazardous alcohol users and 335 (40.9%) abused drugs; 172 (21.0%) had been raped in the last 2 years and 70 (40.7%) of these accessed emergency contraception post-rape. Dual contraception use (condom and other modern method) was 58.0%. Having a non-emotional partner as a man who impregnated the FSW compared to emotional partner was significantly associated with less planned relative to unplanned pregnancy, (aRR = 0.15 95%Cl =0.08, 0.30), so was lack of reported social support compared to support from friends, (aRR = 0.44; 95% CI = 0.22-0.87), keeping all factors constant in the model. Being raped (aRR = 0.51; 95% CI = 0.31-0.84) or abuse of substances (aRR = 0.65; 95% CI = 0.45-0.93) were significantly associated with lower ambivalence relative to unplanned pregnancy but not with planned relative to unplanned pregnancy. CONCLUSION: Compared to women in the general population, pregnancy planning was low among FSWs amidst modest use of dual contraceptive. There is an urgent need to promote dual contraception among FSWs to prevent unplanned pregnancies especially with non-emotional partners, drug users, and post-rape