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We present the pulse arrival times and high-precision dispersion measure estimates for 14 millisecond pulsars observed simultaneously in the 300
500 MHz and 1260
1460 MHz frequency bands using the upgraded Giant Metrewave Radio Telescope. The data spans over a baseline of 3.5 years (2018-2021), and is the first official data release made available by the Indian Pulsar Timing Array collaboration. This data release presents a unique opportunity for investigating the interstellar medium effects at low radio frequencies and their impact on the timing precision of pulsar timing array experiments. In addition to the dispersion measure time series and pulse arrival times obtained using both narrowband and wideband timing techniques, we also present the dispersion measure structure function analysis for selected pulsars. Our ongoing investigations regarding the frequency dependence of dispersion measures have been discussed. Based on the preliminary analysis for five millisecond pulsars, we do not find any conclusive evidence of chromaticity in dispersion measures. Data from regular simultaneous two-frequency observations are presented for the first time in this work. This distinctive feature leads us to the highest precision dispersion measure estimates obtained so far for a subset of our sample. Simultaneous multi-band upgraded Giant Metrewave Radio Telescope observations in 300
500 MHz and 1260
1460 MHz are crucial for high-precision dispersion measure estimation and for the prospect of expanding the overall frequency coverage upon the combination of data from the various Pulsar Timing Array consortia in the near future. Parts of the data presented in this work are expected to be incorporated into the upcoming third data release of the International Pulsar Timing Array.
Several social determinants of health (SDoH) have been associated with the onset of major depressive disorder (MDD). However, prior studies largely focused on individual SDoH and thus less is known about the relative importance (RI) of SDoH variables, especially in older adults. Given that risk factors for MDD may differ across the lifespan, we aimed to identify the SDoH that was most strongly related to newly diagnosed MDD in a cohort of older adults.
We used self-reported health-related survey data from 41 174 older adults (50–89 years, median age = 67 years) who participated in the Mayo Clinic Biobank, and linked ICD codes for MDD in the participants' electronic health records. Participants with a history of clinically documented or self-reported MDD prior to survey completion were excluded from analysis (N = 10 938, 27%). We used Cox proportional hazards models with a gradient boosting machine approach to quantify the RI of 30 pre-selected SDoH variables on the risk of future MDD diagnosis.
Following biobank enrollment, 2073 older participants were diagnosed with MDD during the follow-up period (median duration = 6.7 years). The most influential SDoH was perceived level of social activity (RI = 0.17). Lower level of social activity was associated with a higher risk of MDD [hazard ratio = 2.27 (95% CI 2.00–2.50) for highest v. lowest level].
Across a range of SDoH variables, perceived level of social activity is most strongly related to MDD in older adults. Monitoring changes in the level of social activity may help identify older adults at an increased risk of MDD.
We introduce pinta, a pipeline for reducing the upgraded Giant Metre-wave Radio Telescope (uGMRT) raw pulsar timing data, developed for the Indian Pulsar Timing Array experiment. We provide a detailed description of the workflow and usage of pinta, as well as its computational performance and RFI mitigation characteristics. We also discuss a novel and independent determination of the relative time offsets between the different back-end modes of uGMRT and the interpretation of the uGMRT observation frequency settings and their agreement with results obtained from engineering tests. Further, we demonstrate the capability of pinta to generate data products which can produce high-precision TOAs using PSR J1909
3744 as an example. These results are crucial for performing precision pulsar timing with the uGMRT.
Gravitational waves from coalescing neutron stars encode information about nuclear matter at extreme densities, inaccessible by laboratory experiments. The late inspiral is influenced by the presence of tides, which depend on the neutron star equation of state. Neutron star mergers are expected to often produce rapidly rotating remnant neutron stars that emit gravitational waves. These will provide clues to the extremely hot post-merger environment. This signature of nuclear matter in gravitational waves contains most information in the 2–4 kHz frequency band, which is outside of the most sensitive band of current detectors. We present the design concept and science case for a Neutron Star Extreme Matter Observatory (NEMO): a gravitational-wave interferometer optimised to study nuclear physics with merging neutron stars. The concept uses high-circulating laser power, quantum squeezing, and a detector topology specifically designed to achieve the high-frequency sensitivity necessary to probe nuclear matter using gravitational waves. Above 1 kHz, the proposed strain sensitivity is comparable to full third-generation detectors at a fraction of the cost. Such sensitivity changes expected event rates for detection of post-merger remnants from approximately one per few decades with two A+ detectors to a few per year and potentially allow for the first gravitational-wave observations of supernovae, isolated neutron stars, and other exotica.
Terminal heat stress leads to sizeable yield loss in late-sown wheat in tropical environments. Several synthetic compounds are known to counteract plant stress emanating from abiotic factors. A field experiment was conducted in Sabour (eastern India) during 2013–2016 to investigate the field efficacy of two synthetic compounds, calcium chloride (CaCl2) and arginine, for improving grain yield of two contrasting wheat cultivars (DBW 14 and K 307) facing terminal heat stress. For this, foliar spray of 18.0 mM CaCl2 at booting (CCB) or anthesis (CCA), 9.0 mM CaCl2 at both booting and anthesis (CCB+A), 2.5 mM arginine at booting (ARGB) or anthesis (ARGA) and 1.25 mM arginine at both booting and anthesis (ARGB+A) treatments along with no-spray and water-spray treatments were evaluated in late-sown wheat. The highest grain yield was recorded in treatment CCB+A, followed by CCA and ARGB+A. However, the effect of these compounds was marginal on grain yield when applied only at the booting stage. Grains/ear and thousand-grain weight were found to be the critical determinants for yield in late-sown wheat. During the anthesis to grain filling period, flag-leaf chlorophyll degradation and increase in relative permeability in no-spray treatment were 34–36% and 29–52%, respectively, but these values were reduced considerably in CCB+A treatment followed CCA. Thus, foliar spray of 9.0 mM CaCl2 both at booting and anthesis stages may be recommended for alleviating the negative impacts of terminal heat stress in late-sown wheat and improving its productivity (>13%).
Infection severity and persistence in a host population is affected by variation in host susceptibility. External disturbance can exacerbate/reduce individual variation by affecting the interactions between the host and its parasites and the dynamics of infection and transmission. We investigated the impact of three sources of disturbance (climate change, the presence of a second parasite species and anthelmintic treatment) on the dynamics of infection and shedding of three common parasites of the rabbit. Data were collected from long-term field studies and laboratory experiments and analysed using mathematical modelling and analytical tools. Our studies show that they all affect host–parasite interactions by altering the intensity of infection and/or the degree of parasite shedding. They also generate patterns of infections that could not have been predicted in the absence of these disturbances or from performing analyses at a different temporal scale. Modelling simulations confirmed the complexity of the processes involved and identified the critical interactions shaping the patterns observed.
In search of a suitable resource conservation technology under pigeonpea (Cajanus cajan L.)–wheat (Triticum aestivum L.) system in the Indo-Gangetic Plains, the effects of conservation agriculture (CA) on crop productivity and water-use efficiency (WUE) were evaluated during a 3-year study. The treatments were: conventional tillage (CT), zero tillage (ZT) with planting on permanent narrow beds (PNB), PNB with residue (PNB + R), ZT with planting on permanent broad beds (PBB) and PBB + R. The PBB + R plots had higher pigeonpea grain yield than the CT plots in all 3 years. However, wheat grain yields under all plots were similar in all years except for PBB + R plots in the second year, which had higher wheat yield than CT plots. The contrast analysis showed that pigeonpea grain yield of CA plots was significantly higher than CT plots in the first year. However, both pigeonpea and wheat grain yields during the last 2 years under CA and CT plots were similar. The PBB + R plots had higher system WUE than the CT plots in the second and third years. Plots under CA had significantly higher WUE and significantly lower water use than CT plots in these years. The PBB + R plots had higher WUE than PNB + R and PNB plots. Also, the PBB plots had higher WUE than PNB in the second and third years, despite similar water use. The interactions of bed width and residue management for all parameters in the second and third years were not significant. Those positive impacts under PBB + R plots over CT plots were perceived to be due to no tillage and significantly higher amount of estimated residue retention. Thus, both PBB and PBB + R technologies would be very useful under a pigeonpea–wheat cropping system in this region.
About a thousand optical absorption features on the interstellar extinction curve popularly known as the Diffuse Interstellar Bands (DIBs) have been observed. The numbers are increasing every year, thanks to the improvement in telescope and spectroscopic technology. Ultra-high resolution spectroscopic observations and emission features corresponding to some of the DIBs suggest that, some if not all, of these features are due to large molecules. The strength of DIBs depend on the amount of reddening which is directly proportional to the amount of material present between the background star and the observer. Since, the strengths of the DIBs are not strongly correlated with each other, there must be several carriers. Time Dependent Density Functional Theory (TDDFT) calculations are useful in narrowing down molecular systems that may be further investigated in the laboratory.
The observations of the unidentified infrared (UIR) bands point towards the widespread presence of Polycyclic Aromatic Hydrocarbon (PAH) molecules. Though, not a single PAH has been discovered in interstellar space, these are the largest molecules suspected to be present. PAHs are stable towards energetic environment prevailing under interstellar conditions rendering these molecules to be good candidates as DIB carriers. We report TDDFT calculations to predict electronic transitions of neutral, protonated-deuteronated and PAHs with five member rings with various sites of protonation and deuteronation. Compared to their neutral forms, these charged isoelectronic forms of PAHs are predicted to have active transitions in the visible region, which means they are suitable candidates as carriers for some of the DIBs and laboratory studies are warranted for these systems.
Radio frequency (RF) and microwave amplifier research has been largely focused on solid-state technology in recent years. This paper presents design and performance characterization of a 50-kW modular solid-state amplifier, operating at 505.8 MHz. It includes architecture selection and design procedures based on circuit and EM simulations for its building blocks like solid-state amplifier modules, combiners, dividers, and directional couplers. Key performance objectives such as efficiency, return loss, and amplitude/phase imbalance are discussed for this amplifier for real-time operation. This amplifier is serving as the state-of-the-art RF source in Indus-2 synchrotron radiation source. Characterization on component level as well as system level of this amplifier serves useful data for RF designers working in communication and particle accelerator fields.
Thin films of InSb with different thickness (t = 5, 10 and 15 kÅ) were
deposited on to glass substrate by flash evaporation technique. The
structural and electrical properties were investigated and the effect of
films thickness on films properties was discussed. XRD analysis of the films
as a function of film thickness revealed that crystallinity improves with
film thickness. Temperature dependence of the Hall parameters were studied
in a wide range, 20 < T < 300 K. The temperature variation of the Hall
coefficient and conductivity shows an activated nature with negative
temperature coefficient confirming that the prepared films of InSb are
semiconducting in nature with n-type conductivity. Size effect was observed
as the defect density is much smaller for thicker films and as a result
electrical conductivity of the films increases with increasing film
thickness with the increase of the charge carriers through the film. An
increase in mobility with sample thickness has been observed. The mobility
variations with temperature revealed a transition from lattice to impurity
scattering in the observed temperature range.
The spectroscopic properties of protonated and deprotonated PAHs are investigated through
Density Functional Theory (DFT) calculations, with reference to their potential
astrophysical significance. Attention is focussed on electronic and rotational
The electronic transport properties of p-type tin selenide (SnSe)
grown by direct vapor transport (DVT) technique were investigated via Hall
effect in the temperature range 40 <T< 300 K. The temperature
dependence of conductivity revealed the existence of impurity energy level
in the band gap of the crystal. The temperature dependence of the carrier
concentration was analyzed using the single-donor – single-acceptor model.
The Hall mobility increases by decreasing temperature up to 120 K and then
decreases along with temperature. The observed temperature dependant
mobility in the temperature range 120 <T< 300 K and 40 <T< 120 K
was found to be limited by homopolar and ionized impurity mode scatterings
The characteristics of heterojunction diode pSe-nMoSe2
fabricated from thermally evaporated p-Se films on n-type Molybdenum
diselenide (MoSe2) grown by direct vapour transport (DVT) technique
have been examined by using current-voltage measurements. To investigate the
dark current transport mechanism in pSe-nMoSe2 heterojunctions the
current-voltage characteristics were measured in the temperature range
100–300 K. The prepared diode shows a rectification ratio of the order of
103 within the range –2 to 2 V. A multi-step tunnelling model was used
to analyze the I-V-T characteristics of the prepared device. The activation
energy determined from the saturation current was about 1.16 eV.
Understanding seasonal changes in age-related incidence of infections can be revealing for disentangling how host heterogeneities affect transmission and how to control the spread of infections between social groups. Seasonal forcing has been well documented in human childhood diseases but the mechanisms responsible for age-related transmission in free-living and socially structured animal populations are still poorly known. Here we studied the seasonal dynamics of Bordetella bronchiseptica in a free-living rabbit population over 5 years and discuss the possible mechanisms of infection. This bacterium has been isolated in livestock and wildlife where it causes respiratory infections that rapidly spread between individuals and persist as subclinical infections. Sera were collected from rabbits sampled monthly and examined using an ELISA. Findings revealed that B. bronchiseptica circulates in the rabbit population with annual prevalence ranging between 88% and 97%. Both seroprevalence and antibody optical density index exhibited 1-year cycles, indicating that disease outbreaks were seasonal and suggesting that long-lasting antibody protection was transient. Intra-annual dynamics showed a strong seasonal signature associated with the recruitment of naive offspring during the breeding period. Infection appeared to be mainly driven by mother-to-litter contacts rather than by interactions with other members of the community. By age 2 months, 65% of the kittens were seropositive.
Y2Ba4CuNbO12 (Y-24Nb1) and silver (Ag) are recognized as potential candidates for improving both flux pinning and the mechanical properties of bulk rare earth (RE)–Ba–Cu–O [(RE)BCO] high-temperature superconductors (HTS). Recent attempts to add Ag2O to superconducting Y-123/Y2Ba4CuNbO12 composites, however, have produced a highly anisotropic morphology of Ag particles in samples grown by top-seeded melt growth (TSMG). This morphology has been attributed to strong particle pushing effects due to the presence of Y-24Nb1 nanoparticles in the composite microstructure. An investigation of the formation of anisotropic Ag particles in the YBCO bulk microstructure indicates that these pushing effects generate different morphological microstructural zones in the composite. These include a zone free of inclusions other than acicular Ag particles, a zone of segregated additives (i.e., Y-24Nb1, Y-211, and Ag), and a zone containing fine Ag and other particles distributed uniformly throughout the local microstructure. The particle pushing/trapping theory has been used to explain these extraordinary features of the distribution of Ag inclusions. The superconducting and mechanical properties of samples containing very fine silver inclusions are also discussed briefly.
Counter current Immunoelectrophoresis was used to detect porcine cysticcrcosis and water soluble extracts of scolex and of scolex with cyst wall were used as antigens. Serum samples from 40 pigs infected with Cysticercus cellulosae, five infected with C. tenuicollis and five with hydatid cysts, and 15 healthy pigs were tested. A sharp and thick concave precipitin band was observed at the point of interaction of antigen and antibody within 90min in 39 sera from infected pigs (97–5%). The precipitin reaction was better in barbitone buffer of pH 8–6 with the well distance at 6 mm. No false or cross reaction were found and the test was rapid and sensitive.
High fluences of low energy Ge+ ions were implanted into Si matrix. We have also deposited Ge and SiO2 composite films by using the Atom beam sputtering (ABS). The as implanted/as-deposited films were irradiated by Swift Heavy Ions (SHI) with various energies and fluences. These pristine and irradiated samples were subsequently characterized by XRD and Raman to understand the crystallization behavior. Raman studies of the films indicate the formation of Ge crystallites as a result of SHI irradiation. Glancing angle X-ray diffraction results also confirm the presence of Ge crystallites in the irradiated samples. Moreover, the crystalline nature of Ge improves with an increase in fluence. Rutherford back scattering was used to quantify the concentration of Ge in SiO2 matrix and the film thickness. These detailed results have been discussed and compared with the ones available in literature. The basic mechanism for crystallization induced by SHI in these films will be presented.
Multi quantum wells of InGaAs/InP grown by metal organic chemical vapor deposition have been irradiated using swift heavy ions. Irradiation has been performed using 150MeV Ag and 200MeV Au ions. Both as-grown and irradiated samples were subjected to rapid thermal annealing at 500 and 7000C for 60s. As-grown, irradiated and annealed samples were subjected to high resolution x-ray diffraction studies. Both symmetric and asymmetric scans were analyzed. The as-grown and Ag ion irradiated samples show sharp and highly ordered satellite peaks whereas, the Au ion irradiated samples show broad and low intense peaks. The higher order satellite peaks of the annealed samples vanished with increase of annealing temperature from 500 to 7000C, indicating mixing induced interfacial disorder. Annealing of irradiated samples show higher mixing and disorder and no higher order satellite peaks were observed. Negligible strain was observed after high temperature annealing of as grown samples. Strain values calculated from the X-ray studies indicate that the irradiated samples have higher strain which has been reduced upon annealing. This indicates that the annealing induced mixing occurs maintaining the lattice parameter close to that of the substrate. The effect of electronic energy loss for interface mixing has been discussed in detail. The role of incident ion fluence in combination with the electronic energy loss will also be discussed in detail. The results have been compared with the literature and discussed in detail.