Accretion disc-corona and jet emission from the radio-loud narrow-line Seyfert 1 galaxy RX J1633.3+4719

We perform X-ray/ultraviolet (UV) spectral and X-ray variability studies of the radio-loud narrow-line Seyfert 1 (NLS1) galaxy RX J1633.3+4719 using XMM-Newton and Suzaku observations from 2011 and 2012. The 0.3-10 keV spectra consist of an ultrasoft component described by an accretion disc blackbody (kT_in = 39.6^{+11.2}_{-5.5} eV) and a power law due to the thermal Comptonization ({\Gamma} = 1.96^{+0.24}_{-0.31}) of the disc emission. The disc temperature inferred from the soft excess is at least a factor of 2 lower than that found for the canonical soft excess emission from radio-quiet NLS1s. The UV spectrum is described by a power law with photon index 3.05^{+0.56}_{-0.33}. The observed UV emission is too strong to arise from the accretion disc or the host galaxy, but can be attributed to a jet. The X-ray emission from RX J1633.3+4719 is variable with fractional variability amplitude $F_{\rm var}$=13.5$\pm1.0$ per cent. In contrast to radio-quiet active galactic nuclei (AGN), X-ray emission from the source becomes harder with increasing flux. The fractional rms variability increases with energy and the rms spectrum is well described by a constant disc component and a variable power-law continuum with the normalization and photon index being anticorrelated. Such spectral variability cannot be caused by variations in the absorption and must be intrinsic to the hot corona. Our finding of possible evidence for emission from the inner accretion disc, jet and hot corona from RX J1633.3+4719 in the optical to X-ray bands makes this object an ideal target to probe the disc-jet connection in AGN.Comment: 12 pages, 11 figures, 3 tables, Published in MNRA

Inversion of Gamow's Formula and Inverse Scattering

We present a pedagogical description of the inversion of Gamow's tunnelling formula and we compare it with the corresponding classical problem. We also discuss the issue of uniqueness in the solution and the result is compared with that obtained by the method of Gel'fand and Levitan. We hope that the article will be a valuable source to students who have studied classical mechanics and have some familiarity with quantum mechanics.Comment: LaTeX, 6 figurs in eps format. New abstract; notation in last equation has been correcte

Effect of Polymer-Surface Mobility on Adhesion in Poly(Methyl Methacrylate)-Tape System

The interaction between two polymer layers, especially adhesion between them, plays an important role in polymer processing and other applications. Detailed knowledge of the molecular structure and dynamics of polymer interfaces, and how they relate to macroscopic mechanical properties, should help designers construct more functional systems. Unfortunately, there have been few studies where both molecular and macroscopic studies have been performed on similar systems. In previous studies from our group, we have probed the dynamics of poly(methyl acrylate) (PMA) and thermal behavior of poly(methyl methacrylate) (PMMA) on silica. These studies helped us paint a picture for strongly bound molecules on silica, where a motional gradient perpendicular to the surface was observed. More mobile, lower Tg, material was found at the air-polymer interface, while less mobile, higher Tg material was found at the polymer-substrate interface. A previous study from our group showed that the glass-transition temperature of PMMA changes with the thickness of the polymer layer on silica. by examining the thermal behavior of the polymer with modulated differential scanning calorimetry (MDSC), it was observed that the glasstransition temperature increases as the thickness of the polymer layer decreases. Blum and Lin have also used the deuterium NMR to probe the dynamics of bulk and silica-absorbed poly(methyl acrylate)-d3 (PMA-d3). It was found that, an increase in the absorbed amount of polymer increased the mobility of polymer at the air-polymer interface and a decrease in the absorbed amount of polymer, decreased the polymer mobility. It is not known how this change in mobility relates to the mechanical properties of polymers, especially adhesion between two polymer layers. Of the various methods available for measuring adhesion-related properties, peeling is considered to be the most convenient. Current theories consider peeling to be the principal mode of separation of an adhesive from the substrate. It is proposed that adhesion strength is proportional to the surface free energy. Research has been done to find the adhesion strength between films and substrates, but there are some questions which remain unanswered like: Does adhesion strength depend on the thickness of the polymer layer? Does adhesion strength relate to the mobility of polymer segments on the surface? in the present report, we summarize some of our macroscopic studies, namely peel tests, on systems similar to those previously studied. We find that the mobility of the polymer chains at the interface play an important role in determining the peel strength between the two polymer layers. We decided to use a 90° peel angle method. At this high angle, the lateral stress in the film is very negligible, thereby reducing the lateral elongation of the film. In addition, at this angle, there is no slip at the interface. Our studies show that as the polymer film thickness decreases, the force required to initiate fracture between two polymer surfaces increases and the fracture energy also increases proportionately. We have also observed how fracture energy changes with a change in film thickness

A high-density relativistic reflection origin for the soft and hard X-ray excess emission from Mrk 1044

We present the first results from a detailed spectral-timing analysis of a long ($\sim$130 ks) XMM-Newton observation and quasi-simultaneous NuSTAR and Swift observations of the highly-accreting narrow-line Seyfert 1 galaxy Mrk 1044. The broadband (0.3$-$50 keV) spectrum reveals the presence of a strong soft X-ray excess emission below $\sim$1.5 keV, iron K$_{\alpha}$ emission complex at $\sim$6$-$7 keV and a `Compton hump' at $\sim$15$-$30 keV. We find that the relativistic reflection from a high-density accretion disc with a broken power-law emissivity profile can simultaneously explain the soft X-ray excess, highly ionized broad iron line and the Compton hump. At low frequencies ($[2-6]\times10^{-5}$ Hz), the power-law continuum dominated 1.5$-$5 keV band lags behind the reflection dominated 0.3$-$1 keV band, which is explained with a combination of propagation fluctuation and Comptonization processes, while at higher frequencies ($[1-2]\times10^{-4}$ Hz), we detect a soft lag which is interpreted as a signature of X-ray reverberation from the accretion disc. The fractional root-mean-squared (rms) variability of the source decreases with energy and is well described by two variable components: a less variable relativistic disc reflection and a more variable direct coronal emission. Our combined spectral-timing analyses suggest that the observed broadband X-ray variability of Mrk~1044 is mainly driven by variations in the location or geometry of the optically thin, hot corona.Comment: 23 pages, 19 figures, 4 tables, Published in MNRA

Evaluation of Rock Characteristics for a Power Plant Site in India

Extensive geotechnical and geophysical investigations were carried out for a power plant site situated on the east coast of southern India. It is proposed to construct the foundation on rock at a depth of 18.0 m below the ground level. The geological and geotechnical characterization of the rock have been presented in this paper. Extensive boreholes were drilled up to 40.0 m to 60.0 m depth and a few boreholes up to 120.0 m depth from the ground level. Seismic crosshole tests were conducted at soil/rock strata upto 65.0 m depth for the determination of S-wave and P-wave velocity at different depths. Dilatometer tests were conducted in weathered and hard rock at 5.0 m interval up to a depth of 65.0 m. Field permeability tests were carried out in deep boreholes by single packer method. Various laboratory tests including UCC, Brazilian, and Point load tests were carried out on rock core samples. Modules obtained from UCC tests are compared with the in-situ modulus obtained from Dilatometer tests. Bearing capacity and settlement analysis are carried out for the proposed raft of about 113 m x 105 m size to be supported on rock. The allowing bearing pressure is estimated based on Rock Mass Rating, RQD and strength of rock cores. The settlement analysis is carried out using modulus obtained from Dilatometer tests and from the laboratory unconfined compression tests on rock core samples. The modulus of subgrade reaction and spring constants in vertical, horizontal and rocking modes of vibration are also evaluated for the static and seismic analysis of the raft

Preclinical Imaging Biomarkers for Postischaemic Neurovascular Remodelling

In the pursuit of understanding the pathological alterations that underlie ischaemic injuries, such as vascular remodelling and reorganisation, there is a need for recognising the capabilities and limitations of in vivo imaging techniques. Thus, this review presents contemporary published research of imaging modalities that have been implemented to study postischaemic neurovascular changes in small animals. A comparison of the technical aspects of the various imaging tools is included to set the framework for identifying the most appropriate methods to observe postischaemic neurovascular remodelling. A systematic search of the PubMed® and Elsevier’s Scopus databases identified studies that were conducted between 2008 and 2018 to explore postischaemic neurovascular remodelling in small animal models. Thirty-five relevant in vivo imaging studies are included, of which most made use of magnetic resonance imaging or positron emission tomography, whilst various optical modalities were also utilised. Notably, there is an increasing trend of using multimodal imaging to exploit the most beneficial properties of each imaging technique to elucidate different aspects of neurovascular remodelling. Nevertheless, there is still scope for further utilising noninvasive imaging tools such as contrast agents or radiotracers, which will have the ability to monitor neurovascular changes particularly during restorative therapy. This will facilitate more successful utility of the clinical imaging techniques in the interpretation of neurovascular reorganisation over time

Placental laterality and uterine artery resistance as predictor of preeclampsia: a prospective study at GMERS Medical College, Dharpur-Patan, North Gujarat, India

Background: Placental abnormality is one of the initial events seen in patients who are destined to develop preeclampsia. The objective was to study whether ultrasonically identified; placental laterality and uterine artery resistance can be used as a predictor for development of preeclampsia.Methods:This prospective observational study was conducted at GMERS Medical College, Dharpur-Patan tertiary care teaching institute in North Gujarat from January 2013 to December 2014. A total 400 non high risk primigravida with singleton pregnancy were included, all patients with diabetes, hypertension, renal disease, and history of smoking were excluded. In all these patients, location of placenta was determined by ultrasonography at 18 to 22 weeks of gestation. Patients who had lateral placenta were subjected for colour Doppler study for determining uterine artery resistance index. All 400 patients were followed till delivery for occurrence of preeclampsia as per ACOG guidelines. All data was analyzed and statistical significance was determined by x2 test and value of p<0.05 is considered significant.Results:Out of 400 cases, 80 (20%) cases had laterally located placenta on ultra sound examination done at 18-24 weeks of gestation. Out of the 80 women with laterally located placenta, 28 (35%) developed preeclampsia. This relationship was statistically significant. All 80 patients who had lateral placenta, 26 patients had raised uterine artery resistance and out of those 26 patients, 22 developed preeclampsia and 54 had no change in uterine artery resistance. Out of those 54 only 6 had preeclampsia (p<0. 001). The sensitivity of determining uterine artery resistance as a predictive test was 84.6%, the specificity 88.8 %, positive predictive value 78.5 % and negative predictive value 92.3%.Conclusion: A chance of preeclampsia is more in patients with lateral placenta but its sensitivity and specificity increases significantly when it is combined with uterine artery velocimetric waveform study, and we can predict preeclampsia in patient who is having lateral placenta and raised uterine artery resistance.

Mentoring the Mentors: Implementation and Evaluation of Four Fogarty-Sponsored Mentoring Training Workshops in Low-and Middle-Income Countries.

A growing body of evidence highlights the importance of competent mentoring in academic research. We describe the development, implementation, and evaluation of four regional 2-day intensive workshops to train mid- and senior-level investigators conducting public health, clinical, and basic science research across multiple academic institutions in low- and middle-income countries (LMICs) on tools and techniques of effective mentoring. Sponsored by the Fogarty International Center, workshops included didactic presentations, interactive discussions, and small-group problem-based learning and were conducted in Lima, Peru; Mombasa, Kenya; Bangalore, India; and Johannesburg, South Africa, from 2013 to 2016. Mid- or senior-level faculty from multiple academic institutions within each region applied and were selected. Thirty faculty from 12 South America-based institutions, 29 faculty from eight East Africa-based institutions, 37 faculty from 14 South Asia-based institutions, and 36 faculty from 13 Africa-based institutions participated, with diverse representation across disciplines, gender, and academic rank. Discussions and evaluations revealed important comparisons and contrasts in the practice of mentoring, and specific barriers and facilitators to mentoring within each cultural and regional context. Specific regional issues related to hierarchy, the post-colonial legacy, and diversity arose as challenges to mentoring in different parts of the world. Common barriers included a lack of a culture of mentoring, time constraints, lack of formal training, and a lack of recognition for mentoring. These workshops provided valuable training, were among the first of their kind, were well-attended, rated highly, and provided concepts and a structure for the development and strengthening of formal mentoring programs across LMIC institutions

Chandra Reveals Heavy Obscuration and Circumnuclear Star Formation in Seyfert 2 Galaxy NGC 4968

We present the Chandra imaging and spectral analysis of NGC 4968, a nearby (z = 0.00986) Seyfert 2 galaxy. We discover extended ($\sim$1 kpc) X-ray emission in the soft band (0.5 - 2 keV) that is neither coincident with the narrow line region nor the extended radio emission. Based on spectral modeling, it is linked to on-going star formation ($\sim$2.6-4 M_{\sun} yr$^{-1}$). The soft emission at circumnuclear scales (inner $\sim$400 pc) originates from hot gas, with kT $\sim$ 0.7 keV, while the most extended thermal emission is cooler (kT $\sim$ 0.3 keV). We refine previous measurements of the extreme Fe K$\alpha$ equivalent width in this source (EW = 2.5$^{+2.6}_{-1.0}$ keV), which suggests the central engine is completely embedded within Compton-thick levels of obscuration. Using physically motivated models fit to the Chandra spectrum, we derive a Compton-thick column density ($N_{\rm H} > 1.25\times10^{24}$ cm$^{-2}$) and an intrinsic hard (2-10 keV) X-ray luminosity of $\sim$3-8$\times 10^{42}$ erg s$^{-1}$ (depending on the presumed geometry of the obscurer), which is over two orders of magnitude larger than that observed. The large Fe K$\alpha$ EW suggests a spherical covering geometry, which could be confirmed with X-ray measurements above 10 keV. NGC 4968 is similar to other active galaxies that exhibit extreme Fe K$\alpha$ EWs (i.e., $>$2 keV) in that they also contain ongoing star formation. This work supports the idea that gas associated with nuclear star formation may increase the covering factor of the enshrouding gas and play a role in obscuring AGN.Comment: 11 pages, 8 figures, 4 tables. Accepted for publication in Ap