Measurements of recombination of electrons with H3(plus) and H5(plus) ions

The electron-ion recombination coefficients for H3(+) and H5(+) ions were determined by means of a microwave afterglow/mass spectrometer apparatus. Measurements of electron density decays in helium-hydrogen mixtures are correlated with the decay of mass-identified ion currents to the wall of the microwave cavity. At low partial pressures of hydrogen in the mixture, the ion H3(+) dominates the ion composition and the ion wall current tracks the electron density decay curves. From recombination controlled electron density decay curves, the values alpha (H3(+)) = (2.9 + or - 0.3), (2.3 + or - 0.3), and (2.0 + or - 0.2) x 0.0000001 cu cm per sec, are obtained at 205, 300 and 450 K, respectively. At higher partial pressures of hydrogen and low temperatures, where (H5(+)) is the dominant ion, the value alpha (H5(+)) = (3.6 + or - 1.0) x 0.0000001 cu cm per sec is obtained at 205 K. The implications of these results concerning ionization levels in the atmospheres of the outer planets and in the interstellar medium are discussed

Moment tensor inversion of perforation shots using distributed acoustic sensing

Distributed acoustic sensing (DAS) fibers have enabled various geophysical applications in unconventional reservoirs. Combined with perforation shots, a DAS fiber can record valuable guided waves that propagate in the reservoir formation and carry information about its properties. However, the representation of perforation shots as seismic sources, needed to conduct quantitative analysis, remains unknown. We model such sources using a superposition of three mechanisms for which we derive the moment tensor representation. Using field DAS data recorded in the same well where the perforations are located, we establish a workflow to invert the resolvable components of the total moment tensor for 100 different perforation shots. By scrutinizing the inversion results, we conjecture that the moment tensor can indicate how effectively a perforation shot creates micro-cracks in the surrounding rock. Furthermore, our inverted moment tensors form the basis for a subsequent elastic full-waveform inversion.Comment: This work has been submitted for publication in Geophysics under the reference GEO-2023-004

A revision on the effectiveness of omega-3 polyunsaturated fatty acids as monotherapy in the treatment of major depressive disorder

Background. Insufficient effectiveness and a difficult tolerability profile of antidepressant drugs for the treatment of major depressive disorder (MDD) have been reported, and polyunsaturated fatty acids (PUFAs) have been posited as reliable therapeutic alternatives. The present study investigated the efficacy of omega-3 PUFAs as monotherapy for MDD. Methods. Two well-trained reviewers independently looked at the most significant randomized clinical trials (RCTs) from the PubMed database regarding PUFAs' employment in MDD compared to placebo; "major depressive disorder"and "omega-3 fatty acids,"or "omega-6 fatty acids,"or "polyunsaturated fatty acids (PUFA),"or "n - 3 polyunsaturated fatty acids,"or "eicosapentaenoic acid (EPA),"or "docosahexaenoic acid (DHA)"were used as the medical subject keywords. Results. Of the initial 96 potential RCTs based on titles and abstracts, 82 studies did not meet the inclusion criteria and were excluded. Six studies were excluded from the remaining 14 after full text revision. Eight RCTs met all the inclusion/exclusion criteria without reporting clear evidence of PUFAs' effectiveness in the treatment of MDD. Conclusion. At present, there is no opportunity to recommend the use of omega-3 PUFAs monotherapy for the treatment of MDD, although their supplementation may be useful in some specific populations

Dynamics of two phosphorelays controlling cell cycle progression in 1 Caulobacter crescentus

In Caulobacter crescentus, progression through the cell cycle is governed by the periodic activation and inactivation of the master regulator CtrA. Two phosphorelays, each initiating with the histidine kinase CckA, promote CtrA activation by driving its phosphorylation and by inactivating its proteolysis. Here, we examined whether the CckA phosphorelays also influence the downregulation of CtrA. We demonstrate that CckA is bifunctional, capable of acting as either a kinase or phosphatase to drive the activation or inactivation, respectively, of CtrA. By identifying mutations that uncouple these two activities, we show that CckA's phosphatase activity is important for downregulating CtrA prior to DNA replication initiation in vivo but that other phosphatases may exist. Our results demonstrate that cell cycle transitions in Caulobacter require and are likely driven by the toggling of CckA between its kinase and phosphatase states. More generally, our results emphasize how the bifunctional nature of histidine kinases can help switch cells between mutually exclusive states

Hydroxylation of d-phenylalanine as a novel approach to detect hydroxyl radicals: Application to cardiac pathophysiology

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Two-Component Signal Transduction Pathways Regulating Growth and Cell Cycle Progression in a Bacterium: A System-Level Analysis

Two-component signal transduction systems, comprised of histidine kinases and their response regulator substrates, are the predominant means by which bacteria sense and respond to extracellular signals. These systems allow cells to adapt to prevailing conditions by modifying cellular physiology, including initiating programs of gene expression, catalyzing reactions, or modifying protein–protein interactions. These signaling pathways have also been demonstrated to play a role in coordinating bacterial cell cycle progression and development. Here we report a system-level investigation of two-component pathways in the model organism Caulobacter crescentus. First, by a comprehensive deletion analysis we show that at least 39 of the 106 two-component genes are required for cell cycle progression, growth, or morphogenesis. These include nine genes essential for growth or viability of the organism. We then use a systematic biochemical approach, called phosphotransfer profiling, to map the connectivity of histidine kinases and response regulators. Combining these genetic and biochemical approaches, we identify a new, highly conserved essential signaling pathway from the histidine kinase CenK to the response regulator CenR, which plays a critical role in controlling cell envelope biogenesis and structure. Depletion of either cenK or cenR leads to an unusual, severe blebbing of cell envelope material, whereas constitutive activation of the pathway compromises cell envelope integrity, resulting in cell lysis and death. We propose that the CenK–CenR pathway may be a suitable target for new antibiotic development, given previous successes in targeting the bacterial cell wall. Finally, the ability of our in vitro phosphotransfer profiling method to identify signaling pathways that operate in vivo takes advantage of an observation that histidine kinases are endowed with a global kinetic preference for their cognate response regulators. We propose that this system-wide selectivity insulates two-component pathways from one another, preventing unwanted cross-talk

Essential Oils of Dennettia Tripetala Bak. f. Stem Bark and Leaf – Constituents and Biological Activities:

The essential oil from the stem bark and leaves of Dennettia tripetala Bak. f. (Annonaceae) growing wild in Ondo State, Nigeria, has been characterized by combined gas chromatography (GC) and gas chromatography-mass spectrometry (GC- MS) analyses. Overall, thirty-six components have been fully identified, thirty-two in the stem-bark oil, and only seven in the leaf oil. In both oils, 2-phenylnitroethane was the main component, ranging between 70 – 76% of the total oils. The profile of the stem bark oil was characterized by a large number of sesquiterpenes, whereas among the few components in the leaf oil, linalool reaches over 17%. When both oils were assayed for antimicrobial activity, only Staphylococcus aureus was susceptible to the stem-bark oil which was more active than leaf oil. For protective effects against UV radiation–induced peroxidation in phosphatidylcholine (PC) liposomes, stem-bark oil also showed greater effectiveness. Activity of the leaf oil against Trichomonas gallinae, was also remarkable

Radial Growth of Qilian Juniper on the Northeast Tibetan Plateau and Potential Climate Associations

There is controversy regarding the limiting climatic factor for tree radial growth at the alpine treeline on the northeastern Tibetan Plateau. In this study, we collected 594 increment cores from 331 trees, grouped within four altitude belts spanning the range 3550 to 4020 m.a.s.l. on a single hillside. We have developed four equivalent ring-width chronologies and shown that there are no significant differences in their growth-climate responses during 1956 to 2011 or in their longer-term growth patterns during the period AD 1110–2011. The main climate influence on radial growth is shown to be precipitation variability. Missing ring analysis shows that tree radial growth at the uppermost treeline location is more sensitive to climate variation than that at other elevations, and poor tree radial growth is particularly linked to the occurrence of serious drought events. Hence water limitation, rather than temperature stress, plays the pivotal role in controlling the radial growth of Sabina przewalskii Kom. at the treeline in this region. This finding contradicts any generalisation that tree-ring chronologies from high-elevation treeline environments are mostly indicators of temperature changes

The pattern of TSH and fT4 levels across different BMI ranges in a large cohort of euthyroid patients with obesity.

Purpose: A multifold association relates the hypothalamo-pituitary-thyroid axis to body weight. The potential underlying mechanisms are incompletely understood. Further, the mild severity of obesity and the small proportion of individuals with obesity in so far published cohort studies provide little insights on metabolic correlates of thyroid function in obesity. Methods: We retrospectively enrolled 5009 adults with obesity (F/M, 3448/1561; age range, 18-87 years; BMI range, 30.0-82.7 kg/m2), without known thyroid disease in a study on TSH and fT4 levels, lipid profile, glucose homeostasis and insulin resistance, anthropometric parameters including BIA-derived fat mass (%FM) and fat-free mass (FFM). Results: The overall reference interval for TSH in our obese cohort was 0.58-5.07 mIU/L. As subgroups, females and non-smokers showed higher TSH levels as compared to their counterparts (p<0.0001 for both), while fT4 values were comparable between groups. There was a significant upward trend for TSH levels across incremental BMI classes in females, while the opposite trend was seen for fT4 levels in males (p<0.0001 for both). Expectedly, TSH was associated with %FM and FFM (p<0,0001 for both). TSH and fT4 showed correlations with several metabolic variables, and both declined with aging (TSH, p<0.0001; fT4, p<0.01). In a subgroup undergoing leptin measurement, leptin levels were positively associated with TSH levels (p<0.01). At the multivariable regression analysis, in the group as a whole, smoking habit emerged as the main independent predictor of TSH (β=-0.24, p<0.0001) and fT4 (β=-0.25, p<0.0001) levels. In non-smokers, %FM (β=0.08, p<0.0001) and age (β=-0.05, p<0.001) were the main significant predictors of TSH levels. In the subset of nonsmokers having leptin measured, leptin emerged as the strongest predictor of TSH levels (β=0.17, p<0.01). Conclusions: Our study provides evidence of a gender- and smoking-dependent regulation of TSH levels in obesity