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Linearisation of the Navier–Stokes equations about the mean of a turbulent flow forms the foundation of popular models for energy amplification and coherent structures, including resolvent analysis. While the Navier–Stokes equations can be equivalently written using many different sets of dependent variables, we show that the properties of the linear operator obtained via linearisation about the mean depend on the variables in which the equations are written prior to linearisation, and can be modified under nonlinear transformation of variables. For example, we show that using primitive and conservative variables leads to differences in the singular values and modes of the resolvent operator for turbulent jets, and that the differences become more severe as variable-density effects increase. This lack of uniqueness of mean-flow-based linear analysis provides new opportunities for optimising models by specific choice of variables while also highlighting the importance of carefully accounting for the nonlinear terms that act as a forcing on the resolvent operator.
Considerable controversy exist regarding clinical presentation, diagnosis, and comorbidities specially Attention Deficit Hyperactivity Disorder (ADHD), in paediatric BPD.
To describe phenomenology and comorbidities of paediatric BPD.
To clinically study the Phenomenology and Comorbidity of Pediatric BPD and to clinically study the comorbidity of ADHD in Pediatric BPD.
78 Subjects (6–16 years) attending child and adolescent psychiatry services of C.S.M.M.U. Lucknow, who fulfilled DSM-IV-TR 2000 criteria for BPD were assessed using K-SADS-PL, child mania rating scale (CMRS),child depression rating scale (CDRS) ADHD-RS and C-GAS.
All the subjects were diagnosed as BPD-I. Their mean chronological age was 13.4 ± 2.1 years. the mean age at onset of BPD was 12.2 ± 2.3 years. the most common symptoms found in manic subjects were increased goal directed activities (100%), distractibility (100%), elation (98.7%), grandiosity (90.5%), physical restlessnesss (82.4%), poor judgment (82.4%) and decreased need for sleep (81.1%). 19 (24.5%) cases of BPD had other current comorbid disorders. the commonest comorbidities were MR (10.26%) and ADHD (10.26%), accompanied by Seizure disorders (2.56%), Oppositional Defiant Disorder (6.41%), substance abuse (3.85%), Anxiety Disorders (2.56%), and Enuresis (1.28).
In children and adolescents elation/grandiosity is more common presentation than Irritability. Comorbidities are rare in paediatric BPD-I. Differentiation of comorbid disruptive behaviour disorders especially ADHD from BPD is possible with respect to age of onset, quality of the disturbed mood, and the course of each disorder.
In healthy volunteers, light acting through serotonin pathways, decreases the threshold for sweet, but not salt taste; similar to SSRI paroxetine. In depressive disorders, there is deficiency of serotonin throughput, which is remedied by SSRI medications, and results in improvement in symptoms of depression. Thus, we report on taste thresholds before and after SSRI treatment.
To study the variation in thresholds for sweet with SSRI treatment in depressed patients in short- and long-term.
To compare the threshold for sweet (test) and salt (control) after 1 and 4 weeks of SSRI escitalopram therapy in depressed patients.
The project was approved by the institutional ethics committee. Following informed consent, depressed patients were initiated on escitalopram 10 mg/d (increased to 15 or 20 mg, if required after 1 week,). Taste recognition threshold, intensity and pleasantness were measured for sweet and salt. Each tastant was made −1 to −3 (100 mM–1 mM). Regional recognition thresholds were determined at the tip of the tongue using a cotton bud well soaked in the tastant.
Three males and 4 females of mean ages 39.1 years completed the study. There was significant shift to the left for sweet thresholds between days 0 and 7, and 7 and 28 [F(Dfn, Dfd) = 9.242 (4.162) P < 0.0001]. A similar shift to the left was seen for salt but day 7 only [F(Dfn, Dfd) = 6.213 (4.162)].
The increase in serotonin throughput as envisaged through SSRI treatment was paralleled by decrease in sweet thresholds.
Disclosure of interest
The authors have not supplied their declaration of competing interest.
We describe the design and deployment of GREENBURST, a commensal Fast Radio Burst (FRB) search system at the Green Bank Telescope. GREENBURST uses the dedicated L-band receiver tap to search over the 960–1 920 MHz frequency range for pulses with dispersion measures out to
. Due to its unique design, GREENBURST is capable of conducting searches for FRBs when the L-band receiver is not being used for scheduled observing. This makes it a sensitive single pixel detector capable of reaching deeper in the radio sky. While single pulses from Galactic pulsars and rotating radio transients will be detectable in our observations, and will form part of the database we archive, the primary goal is to detect and study FRBs. Based on recent determinations of the all-sky rate, we predict that the system will detect approximately one FRB for every 2–3 months of continuous operation. The high sensitivity of GREENBURST means that it will also be able to probe the slope of the FRB fluence distribution, which is currently uncertain in this observing band.
Motivated by the problem of jet–flap interaction noise, we study the tonal dynamics that occurs when an isothermal turbulent jet grazes a sharp edge. We perform hydrodynamic and acoustic pressure measurements to characterise the tones as a function of Mach number and streamwise edge position. The observed distribution of spectral peaks cannot be explained using the usual edge-tone model, in which resonance is underpinned by coupling between downstream-travelling Kelvin–Helmholtz wavepackets and upstream-travelling sound waves. We show, rather, that the strongest tones are due to coupling between Kelvin–Helmholtz wavepackets and a family of trapped, upstream-travelling acoustic modes in the potential core, recently studied by Towne et al. (J. Fluid Mech. vol. 825, 2017) and Schmidt et al. (J. Fluid Mech. vol. 825, 2017). We also study the band-limited nature of the resonance, showing the high-frequency cutoff to be due to the frequency dependence of the upstream-travelling waves. Specifically, at high Mach number, these modes become evanescent above a certain frequency, whereas at low Mach number they become progressively trapped with increasing frequency, which inhibits their reflection in the nozzle plane.
Recent observations demonstrate a significant ameliorative effect of add-on transcranial direct current stimulation (tDCS) on auditory verbal hallucinations (AVHs) in schizophrenia. Of the many SNPs, NRG1 rs35753505 and catechol-o-methyl transferase (COMT) rs4680 polymorphisms have shown to have a strong association with neuroplasticity effect in schizophrenia.
Schizophrenia patients (n=32) with treatment resistant auditory hallucinations were administered with an add-on tDCS. The COMT (rs4680) and NRG1 (rs35753505) genotypes were determined. The COMT genotypes were categorised into Val group (GG; n=15) and Met group (GG/AG; n=17) and NRG1 genotypes were categorised into AA group (n=12) and AG/GG group (n=20).
The reduction in auditory hallucination sub-scale score was significantly affected by COMT-GG genotype [Time×COMT interaction: F(1,28)=10.55, p=0.003, ɳ2=0.27]. Further, COMT-GG effect was epistatically influenced by the co-occurrence of NRG1-AA genotype [Time×COMT×NRG1 interaction: F(1,28)=8.09, p=0.008, ɳ2=0.22]. Irrespective of genotype, females showed better tDCS response than males [Time×Sex interaction: F(1,21)=4.67, p=0.04, ɳ2=0.18].
COMT-GG and NRG1-AA genotypes aid the tDCS-induced improvement in AVHs in schizophrenia patients. Our preliminary observations need replication and further systematic research to understand the neuroplastic gene determinants that modulate the effect of tDCS.
We assessed the effect of vitamin D supplementation on related biochemistry, infection and dentition of the infant. In a double-blind, placebo-controlled trial conducted in Lucknow, India (latitude 26°N), 230 mother –newborn pairs were randomised to receive, for 9 months, 3000µg/month oral vitamin D3 by the mother (group A) or 10µg/d by the infant (group B) or double placebo (group C). All babies received 15 min of sun exposure (unclothed) during massage. Infants’ median 25-hydroxyvitamin D (25(OH)D) was lower in group C (median 45·3; interquartile range (IQR) 22–59·5 nmol/l) than in groups A (median 60·8; IQR 41·3–80·5 nmol/l (P<0·01)) and B (median 61·3; IQR 41·3–75·3 nmol/l (P<0·05)) at 3·5 months. Infant 25(OH)D correlated negatively with infant parathyroid hormone (r −0·46, P<0·01). Elevated alkaline phosphatase (>7.5µkat/l) was significantly more frequent in group C babies (16 %) than in group A (4 %) or group B (0 %) babies. The number of days with respiratory or diarrhoeal infection by 9 months of age was higher in group C (median 46·5; IQR 14·8–73·3 d) than in group A (median 18·5; IQR 8·8–31·0 d (P<0·01)) or group B (median 13·0; IQR 7·0–28·5 (P<0·05)). We conclude that monthly maternal or daily infant supplementation with vitamin D along with sun exposure is superior to sun exposure alone in maintaining normal infant 25(OH)D at 3·5 months, and provide protection from elevated alkaline phosphatase and infectious morbidity.
Soybean is a leading oilseed crop in India, which contains about 40% of protein and 20% of oil. Core collection will accelerate the management and utilization of soybean genetic resources in breeding programmes. In the present study, eight agromorphological traits of 3443 soybean germplasm were analysed for the development of core collection using the principal component score (PCS) strategy and the power core method. The PCS strategy yielded core collection (CC1) of 576 accessions, which accounted for 16.72% of the entire collection (EC). The analysis based on the power core programme resulted in CC2 of 402 accessions, which accounted for 11.67% of the EC. Statistical analysis showed similar trends for the mean and range estimated in both core collections and EC. In addition, the variance, standard deviation and coefficient of variance were in general higher in core collections than in the EC. The correlations observed in the EC in general were preserved in core collections. A total of 311 and 137 unique accessions were found in CC1 and CC2 in addition to 265 accessions that were found to be common in both core collections. These 265 common accessions were the most diverse core sets, which accounted for 7.64% of the EC. We proposed to constitute an integrated core collection (ICC) by integrating both common and unique accessions. The ICC comprised 713 accessions, which accounted for about 20.62% of the EC. Statistical analysis indicated that the ICC captured maximum variation than CC1 and CC2. Therefore, the ICC can be extensively evaluated for a large number of economically important traits for the identification of desirable genotypes and for the development of mini core collection in soybean.
We investigate source mechanisms for subsonic jet noise using experimentally obtained datasets of high-Reynolds-number Mach 0.4 and 0.6 turbulent jets. The focus is on the axisymmetric mode which dominates downstream sound radiation for low polar angles and the frequency range at which peak noise occurs. A linearized Euler equation (LEE) solver with an inflow boundary condition is used to generate single-frequency hydrodynamic instability waves, and the resulting near-field fluctuations and far-field acoustics are compared with those from experiments and linear parabolized stability equation (LPSE) computations. It is found that the near-field velocity fluctuations closely agree with experiments and LPSE computations up to the end of the potential core, downstream of which deviations occur, but the LEE results match experiments better than the LPSE results. Both the near-field wavepackets and the sound field are observed directly from LEE computations, but the far-field sound pressure levels (SPLs) obtained are more than an order of magnitude lower than experimental values despite close statistical agreement of the near hydrodynamic field up to the potential core region. We explore the possibility that this discrepancy is due to the mismatch between the decay of two-point coherence with increasing distance in experimental flow fluctuations and the perfect coherence in linear models. To match the near-field coherence, experimentally obtained coherence profiles are imposed on the two-point cross-spectral density (CSD) at cylindrical and conical surfaces that enclose near-field structures generated with LEEs. The surface pressure is propagated to the far field using boundary value formulations based on the linear wave equation. Coherence matching yields far-field SPLs which show improved agreement with experimental results, indicating that coherence decay is the main missing component in linear models. The CSD on the enclosing surfaces reveals that the application of a decaying coherence profile spreads the hydrodynamic component of the linear wavepacket source on to acoustic wavenumbers, resulting in a more efficient acoustic source.
Transcranial direct current stimulation (tDCS) is a non-invasive and well-tolerated brain stimulation technique with promising efficacy as an add-on treatment for schizophrenia and for several other psychiatric disorders. tDCS modulates neuroplasticity; psychiatric disorders are established to be associated with neuroplasticity abnormalities. This review presents the summary of research on potential genetic basis of neuroplasticity-modulation mechanism underlying tDCS and its implications for treating various psychiatric disorders.
A systematic review highlighting the genes involved in neuroplasticity and their role in psychiatric disorders was carried out. The focus was on the established genetic findings of tDCS response relationship with BDNF and COMT gene polymorphisms.
Synthesis of these preliminary observations suggests the potential influence of neuroplastic genes on tDCS treatment response. These include several animal models, pharmacological studies, mentally ill and healthy human subject trials.
Taking into account the rapidly unfolding understanding of tDCS and the role of synaptic plasticity disturbances in neuropsychiatric disorders, in-depth evaluation of the mechanism of action pertinent to neuroplasticity modulation with tDCS needs further systematic research. Genes such as NRG1, DISC1, as well as those linked with the glutamatergic receptor in the context of their direct role in the modulation of neuronal signalling related to neuroplasticity aberrations, are leading candidates for future research in this area. Such research studies might potentially unravel observations that might have potential translational implications in psychiatry.
Wavepackets obtained by a linear stability analysis of the turbulent mean flow were shown in recent works to agree closely with some relevant statistics of turbulent jets, such as power spectral densities and averaged phases of flow fluctuations. However, when such wavepacket models were used to calculate the far-field sound, satisfactory agreement was only obtained for flows that were supersonic relative to the ambient speed of sound; attempts with subsonic flows led to errors of more than an order of magnitude. We investigate here the reasons for such discrepancies by developing the integral solution of the Helmholtz equation in terms of the cross-spectral densities of turbulent quantities. It is shown that agreement of a statistical source, such as would be obtained by the above-mentioned wavepacket models, in averaged amplitudes and phases in the near field is not a sufficient condition for exact agreement of the far-field sound. The sufficient condition is that, in addition to the amplitudes and phases, the statistical source should also match the coherence function of the flow fluctuations. This is exemplified in a model problem, where we show that the effect of coherence decay on sound radiation is more prominent for subsonic convection velocities, and its neglect leads to discrepancies of more than an order of magnitude in the far-field sound. For supersonic flows errors are reduced for the peak noise direction, but for other angles the coherence decay is also seen to have a significant effect. Coherence decay in the model source is seen to lead to similar decays in the coherence of two points in the far acoustic field, these decays being significantly faster for higher Mach numbers. The limitations of linear wavepacket models are illustrated with another simplified problem, showing that superposition of time-periodic solutions can lead to a correlation decay between two points. However, the coherence between any pair of points in such models remains unity, and cannot thus represent the behaviour observed in turbulent flows.
This paper details the development of a technique to improve the minority carrier lifetime of 4H-SiC thick (≥ 100 μm) n-type epitaxial layers through multiple thermal oxidations. A steady improvement in lifetime is seen with each oxidation step, improving from a starting ambipolar carrier lifetime of 1.09 µs to 11.2 µs after 4 oxidation steps and a high-temperature anneal. This multiple-oxidation lifetime enhancement technique is compared to a single high-temperature oxidation step, and a carbon implantation followed by a high-temperature anneal, which are traditional ways to achieve high ambipolar lifetime in 4H-SiC n-type epilayers. The multiple oxidation treatment resulted in a high minimum carrier lifetime of 6 µs, compared to < 2 µs for other treatments. The implications of lifetime enhancement to high-voltage/high-current 4H-SiC power devices are also discussed.
The conventional method to fabricate porous silicon with n-type substrates requires light assisted generation of holes used in the electrochemical reaction. Recently, two different methods have been proposed to fabricate some similar structures: Hall effect  and lateral electrical field . Hall effect assisted etching involves the application of a perpendicular electric and magnetic field to achieve the concentration of holes at the HF/silicon interface to assist the electrochemical reaction, while the other involves the application of a lateral electrical field across the silicon wafer. In this work, the electrochemical etching of high resistivity n-type silicon wafers under the combined effect of magnetic and lateral electrical field to produce photoluminescent macroporous structures under dark conditions, is reported. A lateral gradient in pore sizes as well as in light emission is observed. Optical and structural properties were studied for their possible applications as a biosensor.
There is a considerable scarcity of reliable population-based data on the prevalence of preventable ear disorders in developing countries. This study was conducted to determine the prevalence of preventable ear disorders in primary school children (aged 5 to 12 years) in northern India.
A pro forma questionnaire was used to screen 15 718 primary school children in New Delhi for ear disorders. Ear examinations were conducted using otoscopy and impedance audiometry.
Impacted cerumen was prevalent in 7.93 per cent of schoolchildren, 4.79 per cent suffered from chronic otitis media and 3.06 per cent suffered from otitis media with effusion. Acute otitis media was detected in 0.65 per cent and foreign bodies were found in 0.34 per cent of the children.
Preventable ear diseases posed a significant health problem among children at primary school level. Regular screening of children during this stage would ensure that their school lives were not affected by hearing impairments or preventable ear disorders. Information gathered in this study will help in effective treatment prioritisation of ear disorders, planning and resource allocation.
Hypovitaminosis D is common in India. In the present prospective partially randomised study of vitamin D (D3) supplementation during pregnancy, subjects were randomised in the second trimester to receive either one oral dose of 1500 μg vitamin D3 (group 1, n 48) or two doses of 3000 μg vitamin D3 each in the second and third trimesters (group 2, n 49). Maternal 25-hydroxyvitamin D (25(OH)D) at term, cord blood (CB) alkaline phosphatase (ALP), neonatal serum Ca and anthropometry were measured in these subjects and in forty-three non-supplemented mother–infant pairs (usual care). Median maternal 25(OH)D at term was higher in group 2 (58·7, interquartile range (IQR) 38·4–89·4 nmol/l) v. group 1 (26·2, IQR 17·7–57·7 nmol/l) and usual-care group (39·2, IQR 21·2–73·4 nmol/l) (P = 0·000). CB ALP was increased (>8.02 μkat/l or >480 IU/l) in 66·7 % of the usual-care group v. 41·9 % of group 1 and 38·9 % of group 2 (P = 0·03). Neonatal Ca and CB 25(OH)D did not differ significantly in the three groups. Birth weight, length and head circumference were greater and the anterior fontanelle was smaller in groups 1 and 2 (3·08 and 3·03 kg, 50·3 and 50·1 cm, 34·5 and 34·4 cm, 2·6 and 2·5 cm, respectively) v. usual care (2·77 kg, 49·4, 33·6, 3·3 cm; P = 0·000 for length, head circumference and fontanelle and P = 0·003 for weight). These differences were still evident at 9 months. We conclude that both 1500 μg and two doses of 3000 μg vitamin D3 had a beneficial effect on infant anthropometry, the larger dose also improving CB ALP and maternal 25(OH)D.
Two dimensional Er3+-TeO2 thin film photonics crystals (PhCs) are fabricated. These PhCs demonstrate broadband enhancement of PL emission at near Infrared (NIR). The PhC structures are written by dual beam focused ion beam (FIB). Highly uniformed patterns with smooth surfaces are observed. A pattern resolution better than hundred nanometers is achieved. PhCs arrays with photonic lattice constants from 350 nm to 1700 nm are examined in order to optimize the PL extraction efficiency. Strong photoluminescence around 1530 nm is observed by 488-532 nm lasers pumping. A confocal microscopy with spectrometer is used to capture the broadband PL signals from individual PhC array.
The emission enhancement factor and spectral dependent extraction ratio are analyzed to find the interaction between PL lightwave and PhC structures. By optimize the PhC structures, 1500 um-1560 um broadband PL is successfully converted between the PL emission layer and the external cavity. A 60 % enhancement of surface extraction efficiency is achieved when PhC with periodicity a=800 nm is applied. When photonic lattice constants a are smaller than the critical periodicity 600 nm, the PL light becomes confined inside the thin film layer. Simulation is also performed by two dimensional finite difference time domain (FDTD) calculation in order to explain the experimental observed anisotropic PL enhancements.
The broadband PL enhancement enables Er3+-TeO2 PhCs thin film as a potential light source for three dimensional integrated photonic circuits.
In the present work an alternative nanoparticle synthesis technique was developed, where the nanoparticles nucleate and grow inside the pores of the nanostructured porous silicon (NPS). Employing green method for the nanoparticle synthesis, yeast extract is used as a reducing agent. The porous layers were prepared by electrochemical etching of Boron-doped (100) Si substrate (0.01-0.02Ohm·cm). The NPS support was immersed into the reactive colloid for different times, then withdrawn, cleaned and dried. SEM and XRD measurements were carried out to characterize the NPS substrate and the immobilized catalyst nanoparticles. EDX mapping shows a homogeneous deposition of nanoparticles on the porous support. The average particle size, calculated from XRD diffractograms (using the Scherrer`s formula), was found between 6 to 10 nm. This method provides a good incorporation and distribution of nanoparticles, also an alternative environment-friendly technique to develop catalytic devices fabricated on silicon substrate with an additional advantage of being integrated with the silicon based microelectronic circuits.
We must be ever prepared to accept and experiment with new materials from all sources and determine what can be useful to us and take the fullest possible advantage of such materials.
Sir C. V. Raman (1958)
Geoinformatics: An Indian perspective
We provide an overview of geoinformatics activities that are being coordinated by the University of Hyderabad, India via two research institutes at the University, viz. the University Center for Earth and Space Sciences (UCESS) and the Center for Modeling, Simulation, and Design (CMSD) (Agarwal, 2006). We also describe cyberinfrastructure-related activities undertaken as part of the iGEON-India project, which has been a collaboration with the GEON project in the USA, supported by a grant from the Indo-US Science and Technology Forum, IUSSTF (Agarwal et al., 2009).
During the past 5 years or so, India has made great strides in mineral and other natural resource surveys using both direct and indirect (satellite-based remotely sensed data) techniques, leading to exploration and exploitation of both mineral and forest wealth, and improved data bases for weather prediction and disaster management. We recognize that wise utilization of our natural resources including, minerals, water, and forests, will be possible only through free and unfettered dissemination of accurate data and timely sharing of such information. Data relating to earth sciences are accumulating at an astonishing rate all over the world. Indeed, it has become impossible to keep pace with the growing tempo of new information from research publications.