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A total of 45 strains of Vibrio cholerae O1 isolated from 10 different places in India where they were associated with cases of cholera between the years 2007 and 2008 were examined by molecular methods. With the help of phenotypic and genotypic tests the strains were confirmed to be O1 El Tor biotype strains with classical ctxB gene. Polymerase chain reaction (PCR) analysis by double – mismatch amplification mutation assay PCR showed 16 of these strains carried the ctxB-7 allele reported in Haitian strains. Sequencing of the ctxB gene in all the 45 strains revealed that in 16 strains the histidine at the 20th amino acid position had been replaced by asparagine and this single nucleotide polymorphism did not affect cholera toxin production as revealed by beads enzyme-linked immunosorbent assay. This study shows that the new ctxB gene sequence was circulating in different places in India. Seven representatives of these 45 strains analysed by pulsed – field gel electrophoresis showed four distinct Not I digested profiles showing that multiple clones were causing cholera in 2007 and 2008.
There is a genetic contribution to the risk of suicide, but sparse prior research on the genetics of suicidal ideation.
Active and passive suicidal ideation were assessed in a Sri Lankan population-based twin registry (n = 3906 twins) and a matched non-twin sample (n = 2016). Logistic regression models were used to examine associations with socio-demographic factors, environmental exposures and psychiatric symptoms. The heritability of suicidal ideation was assessed using structural equation modelling.
The lifetime prevalence of any suicidal ideation was 13.0% (11.7–14.3%) for men; 21.8% (20.3–23.2%) for women, with no significant difference between twins and non-twins. Factors that predicted suicidal ideation included female gender, termination of marital relationship, low education level, urban residence, losing a parent whilst young, low standard of living and stressful life events in the preceding 12 months. Suicidal ideation was strongly associated with depression, but also with abnormal fatigue and alcohol and tobacco use. The best fitting structural equation model indicated a substantial contribution from genetic factors (57%; CI 47–66) and from non-shared environmental factors (43%; CI 34–53) in both men and women. In women this genetic component was largely mediated through depression, but in men there was a significant heritable component to suicidal ideation that was independent of depression.
These are the first results to show a genetic contribution to suicidal ideation that is independent of depression outside of a high-income country. These phenomena may be generalizable, because previous research highlights similarities between the aetiology of mental disorders in Sri Lanka and higher-income countries.
We address two aspects of finitely generated modules of finite projective dimension over local rings and their connection in between: embeddability and grade of order ideals of minimal generators of syzygies. We provide a solution of the embeddability problem and prove important reductions and special cases of the order ideal conjecture. In particular, we derive that, in any local ring R of mixed characteristic p > 0, where p is a nonzero divisor, if I is an ideal of finite projective dimension over R and p 𝜖 I or p is a nonzero divisor on R/I, then every minimal generator of I is a nonzero divisor. Hence, if P is a prime ideal of finite projective dimension in a local ring R, then every minimal generator of P is a nonzero divisor in R.
We develop a framework for analysing the outcome of resource competition based on
bifurcation theory. We elaborate our methodology by readdressing the problem of
competition of two species for two resources in a chemostat environment. In the case of
perfect-essential resources it has been extensively discussed using Tilman’s
representation of resource quarter plane plots. Our mathematically rigorous analysis
yields bifurcation diagrams with a striking similarity to Tilman’s method including the
interpretation of the consumption vector and the resource supply vector. However, our
approach is not restricted to a particular class of models but also works with other
trophic interaction formulations. This is illustrated by the analysis of a model
considering interactively-essential or complementary resources instead of
prefect-essential resources. Additionally, our approach can also be used for other
ecosystem compositions: multiple resources–multiple species communities with equilibrium
or oscillatory dynamics. Hence, it gives not only a new interpretation of Tilman’s
graphical approach, but it constitutes an extension of competition analyses to communities
with many species as well as non-equilibrium dynamics.
A temporal relationship of Japanese encephalitis virus (JEV) transmission in pigs, mosquitoes and humans revealed that sentinel pig seroconversions were significantly associated with human cases 4 weeks before (P = 0·04) their occurrence, highly correlated during the same time and 2 weeks before case occurrence (P < 0·001), and remained significantly correlated up to 2 weeks after human case occurrence (P < 0·01). JEV was detected in the same month in pigs and mosquitoes, and peaks of pig seroconversion were preceded by 1–2 months of peaks of infection in vectors. Kaplan–Meier analysis indicated that detection of JEV-positive mosquitoes was significantly associated with the median time to occurrence of seroconversion in pigs (P < 0·05). This study will not only help in predicting JEV activity but also accelerate timely vector control measures and vaccination programmes for pigs and humans to reduce the Japanese encephalitis risk in endemic areas.
Four series of samples, prepared at 250° C by decomposition of a mixture of silane and argon in a radio frequency powered deposition systems (rf-PECVD), have been studied. The dilution rates were 1 %, 1.5 %, 5 % and 10 % of silane in argon and the total pressure was 0.5 Torr for the first series and 0.2 Torr for the others. Structural and transport properties of the materials have been studied as function of power density. Structural studies show the transition from purely amorphous material towards microcrystalline material with increasing rf power density. The transport parameters were measured in the as-deposited, light-soaked and annealed states and compared to those obtained on state of the art material. The best material obtained is clearly device grade material. This study shows that argon dilution allows to tailor the material for a given application.
The multilayers of ferroelectric (FE) Pb(Zr, Ti)O3 (PZT) and ferromagnetic (FM) CoFe2O4 (CFO) thin films with 3, 5, and 9 layers having configurations PZT/CFO (PC) and CFO/PZT (CP) were fabricated by pulsed laser deposition technique. We have investigated the effect of inter-diffusion at the interface of multilayers (MLs) and reversing the order of FE and FM layers in the multilayers configuration on the electrical/magnetic properties. The TEM of the films showed that the layer structure was not maintained and the inter-diffusion of the CFO into PZT and vice verse were observed at the interface of MLs. Both the PC and CP configurations of multilayer films exhibited pseudo FE hysteresis loop and proper FM hysteresis loops at room temperature. Reversing the multilayer configuration from CP to PC resulted in increasing the pseudo remanent polarization, however this behavior was not observed in magnetic properties. The frequency and temperature dependences of the impedance and modulus spectroscopy of the multilayer PC and CP films were studied in the ranges of 102 to 106 Hz and 200 to 650 K respectively. The electrical response of all multilayer films investigated could be resolved into two contributions. We attributed these to the grain and grain boundary effects in impedance and modulus formalism. We found that the difference between the grain and grain boundary capacitive effect decreased due to increase of the number of layers.
In order to produce a three-dimensional interconected graphitic network, foams were produced from carbon fiber precursor pitch and processed similarly to high modulus carbon fibers. Uniform size distributions of open spherical cell graphitic carbon foams were produced by microcellular foam blowing of anisotropic pitch using homogeneous and heterogeneous nucleation. The widths of cell walls and ligaments were in the range of the diameters of pitch-based carbon fibers (7-10 μm) and possessed significant alignment of anisotropic pitch crystallites.
Thermal oxidation of Silicon in the thin regime is of vital importance to VLSI device engineers because thin layers of SiO2 are exclusively used as the gate dielectric for high performance of MOS devices. There exists a number of models to explain this kinetics of oxidation. However there is a considerable variance among the reported rate constants, which are supposed to describe the oxidation process. Rather than arriving at an alternative model, the present study aims at simulation of existing models of oxidation in dry oxygen, with a recent set of experimental data and arrive at the best possible model and provide accurate rate constants for oxidation in dry oxygen. These experimental data have been obtained, earlier, using high-resolution transmission electron microscopy (HRTEM) and ellip-sometry techniques to measure thicknesses of silicon oxide, grown at 800° in dry oxygen, in the thickness range of 2–20 nm.
Cathodoluminescence (CL) technique has been employed to study the optical properties of GaSb after deposition of hydrogenated amorphous silicon (a-Si:H). CL images recorded at various depths in the samples clearly show passivation of extended defects on the surface as well as in the bulk region. The passivation of various recombination centres in the bulk is attributed to formation of hydrogen-impurity complexes by diffusion of hydrogen ions from the plasma. Enhancement in luminescence intensity is seen due to passivation of non-radiative recombination centres. The passivation efficiency is found to improve with increase in a-Si:H deposition temperature.
GaSb p-n junctions formed by Zn diffusion in Te-doped n-GaSb single crystalline wafers have been characterized by cathodoluminescence (CL) microscopy and by scanning tunneling spectroscopy. CL plane-view observations of the Zn diffused side enable to study the homogeneity of the diffusion treatment. Spectra recorded by current imaging tunneling spectroscopy (CITS) in the n and p sides of the junction, clearly show the respective conductive behaviour and provide information on the local surface band gaps. Results are related to the diffusion profile measured by secondary ion mass spectrometry (SIMS).
Radio-frequency (RF) photoreflectance measurements and one-dimensional device simulations have been used to evaluate bulk recombination parameters and surface recombination velocity (SRV) in doubly-capped 0.55-eV p-InGaAsSb epitaxial layers, doped at 2 × 1017 cm-3, for thermophotovoltaic (TPV) applications. Bulk lifetimes of 90 to 100 ns and SRVs of 680 cm/s to 3200 cm/s (depending on the capping layer) are obtained, with higher doping and higher bandgap capping layers most effective in reducing SRV. RF photoreflectance measurements and one-dimensional device simulations are compatible with a radiative recombination coefficient (B) of 3 × 10-11 cm3/s and Auger coefficient (C) of 1 × 10-28 cm6/s.
We have studied the structural evolution in amorphous and microcrystalline silicon deposited from silane-argon mixture by radio frequency plasma enhanced chemical vapour deposition (PECVD) method. Sharp increase in small angle x-ray scattering (SAXS) intensity, in accordance with tilt measurements, indicates columnar morphology in the sample deposited in the amorphous-microcrystalline transition region. The variation of SAXS measured heterogeneity and a gradual shift of Si-H stretching vibrational frequency at 2000 cm-1 towards higher wave number with increase of power density indicate structural modifications in the films. Observation of sharp increase in the ratio of the intensity of Ar* to SiH* in the transition region may explain the surface modification assisted by Ar* and hence the structural changes in the material.
Information and communication technologies, especially in the forms of mobile telecommunications, satellite imaging, and geographical information systems, promise to significantly improve the practice of humanitarian relief. A working group convened at the Humanitarian Action Summit 2009, has begun investigating the challenges to implementing these technologies in field operations, keeping in mind the ethical considerations of linking people to place, and pledging to build a community of practice among academics, practitioners, and developers.
Polycrystalline electroceramics have been prepared by varying modifier to former (Bi/La) ratios (
) according to the complex formula
Biz] 0.08[Zr0.65Ti0.35] 0.98O3 (PLBZT), where z = 0.0, 0.3, 0.6.
The electrical properties of PLBZT compounds were studied using the ac
impedance spectroscopy technique over a wide range of temperature
(30–500 °C) in the frequency range of 100 Hz–1 MHz.
Nyquist plots recorded at different temperatures show a decrease in the bulk
resistance (Rb) with rise in temperature for PLZT material (z = 0.0)
i.e., NTCR behavior like semiconductors. The Nyquist plots also indicates
that the bulk resistance of the material has been observed to be
concentration dependent and decreased in two order of magnitude with higher
Bi-addition in PLZT matrix. Bismuth (Bi) substitution at the lanthanum (La)
position not only resulted in lowering of the electrical resistance with its
higher concentration but also has changed the NTCR behavior of PLZT (z = 0.0) to PTCR (positive temperature coefficient of resistance) for PLBZT.
Electrical property studied by complex impedance spectroscopic method also
indicates the evidence of (i) single electrical relaxation attributed to the
presence of bulk contribution to the electrical properties, (ii) presence of
temperature dependent electrical relaxation phenomenon and (i) diminution in
the barrier to the mobility of charge carrier on Bi-substitution.
Background and objective: We studied the effect of different recumbent positions (supine, left and right lateral decubitus), on arterial oxygenation in 42 valvular heart disease patients planned for cardiac surgery. All patients had cardiomegaly (cardiothoracic ratio ≥0.5) in their chest X-rays. Their left ventricular end-diastolic diameter was also noted from the preoperative echocardiogram. Methods: Arterial blood gas analysis was performed in supine, left and right lateral positions after keeping the patient in a given position for 15 min. During this period all patients received 35% oxygen supplementation. Results: Arterial oxygen tension and haemoglobin saturation were significantly higher in the right lateral position (PaO2 = 120.6 ± 29.5 mmHg, SaO2 = 98.1 ± 1.4%) than in supine (PaO2 = 111.0 ± 30.6 mmHg, SaO2 = 97.6 ± 2.2%) and left lateral positions (PaO2 = 109.7 ± 32.0 mmHg, SaO2 = 97.6 ± 1.7%; mean ± SD; P < 0.01). There was no significant difference in arterial oxygenation between left lateral and supine positions (P > 0.05). The change in PaO2 and SaO2 with change of posture from left to right was significantly related to left ventricular end-diastolic diameter (r = 0.50 and r = 0.63, respectively; Pearson correlation). Repeated measures of analysis of variance with left ventricular end-diastolic diameter as a covariate showed a significant change in arterial PaO2 with posture (P = 0.011). Conclusion: Right lateral posture improves arterial oxygenation in the valvular heart disease patient with an enlarged left ventricle. In the preoperative period, these patients may benefit from a right lateral posture when lying in bed.
Many different drug-resistant lines of rodent malaria are available as screening models. It is obligatory to screen new compounds for antimalarial activity against a series of resistant lines in order to identify a compound with potential for the treatment of multi-drug resistant (MDR) malaria infections. Instead of using a battery of resistant lines, a single MDR Plasmodium yoelii nigeriensis strain that shows a wide spectrum of drug resistance to high doses of chloroquine, mepacrine, amodiaquine, mefloquine, quinine, quinidine, halofantrine as well as tetracyclines, fluoroquinolines and erythromycin, was used to assess the blood schizontocidal efficacy of a new macrolide azithromycin and other antibiotics. The present study shows that only azithromycin has the potential to control an MDR P. y. nigeriensis infection in Swiss mice, provided the treatment with a dose of 50–100 mg/kg/day by oral route is continued for a period of 7 days. Tetracycline, oxytetracycline, doxycyline, erythromycin, ciprofloxacin and norfloxacin, although active in vitro, failed to protect the mice. Tetracycline, ciprofloxacin and norfloxacin combinations with chloroquine did not control the infection. Additionally, the antimalarial efficacy of azithromycin can be potentiated with the addition of arteether, which is an ethyl ether derivative of artemisinin. A total (100%) curative effect has been obtained with a shorter regimen of 4 days only.
One hundred and sixty-six shigellae strains, isolated from stool samples of paediatric patients (<5 years old) at a Childrens' Hospital in Kolkata, India during the period of 1995–2000 were examined for serotyping, drug resistance pattern and plasmid profiles. Sh. flexneri (58%) was found to be commonest isolate of total shigellae, followed by Sh. sonnei (28%), Sh. boydii (9%) and Sh. dysenteriae (5%). This profile of species was in sharp contrast to the picture obtained before 1995, when Sh. dysenteriae 1 predominated over Sh. flexneri. In Sh. flexneri strains, Sh. flexneri 2a (35%) was the most prevalent serotype, following Sh. flexneri 3a (31%), Sh. flexneri 6 (14%), Sh. flexneri 2b (11%) and Sh. flexneri 4 (9%). Resistance patterns of the strains to 12 commonly used antimicrobial agents and minimum inhibitory concentrations (MICs) of the antibiotics were also tested. All strains were found uniformly susceptible to norfloxacin, but more than 90% strains were resistant to tetracycline, co-trimoxazole and 67% strains were resistant to ampicillin. Resistance to amoxicillin, chloramphenicol and nalidixic acid was found in 55% (range 45–74%), 46% (range 40–60%) and 29% (range 15–40%) strains respectively. Overall, shigellae strains showed statistically significant increase in resistance against tetracycline, nalidixic acid and furazolidone (P<0.05) over the years of this study. This indicates decreased efficacy of furazolidone, cotrimoxazole and nalidixic acid for the empirical treatment of shigellosis in Kolkata. Although a few strains showed intermediate susceptibility to ciprofloxacin (4%) and cefotaxime (10%) by disk diffusion test, but the MICs of those antibiotics were within the normal limits. Almost 57% of the strains were resistant to four or more drugs with high MICs of the antibiotics. Plasmid profile analysis revealed presence of large plasmid of 220 kb in majority of the strains except in Sh. sonnei and a correlation between presence of smaller plasmids and shigellae serotypes. Hence this study reports epidemiological change of shigellae species in Kolkata, India with regard to serotypes and antibiotic resistance patterns.