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The Infectious Diseases and Beliaghata General Hospital, Kolkata, India witnessed a sudden increase in admissions of diarrhoea cases during the first 2 weeks of August 2015 following heavy rainfall. This prompted us to investigate the event. Cases were recruited through hospital-based surveillance along with the collection of socio-demographic characteristics and clinical profile using a structured questionnaire. Stool specimens were tested at bacteriological laboratory of the National Institute of Cholera and Enteric Diseases (NICED), Kolkata. Admission of 3003 diarrhoea cases, clearly indicated occurrence of outbreak in Kolkata municipal area as it was more than two standard deviation of the mean number (911; s.d. = 111) of diarrhoea admissions during the same period in previous 7 years. Out of 164 recruited cases, 25% were under-5 children. Organisms were isolated from 80 (49%) stool specimens. Vibrio cholerae O1 was isolated from 50 patients. Twenty-eight patients had this organism as the sole pathogen. Among 14 infants, five had cholera. All V. cholerae O1 isolates were resistant to nalidixic acid, followed by co-trimoxazole (96%), streptomycin (92%), but sensitive to fluroquinolones. We confirmed the occurrence of a cholera outbreak in Kolkata during August 2015 due to V. cholerae O1 infection, where infants were affected.
Socio-behavioural factors and pathogens associated with childhood diarrhoea are of global public health concern. Our survey in 696 children aged ⩽2 years in rural West Bengal detected rotavirus as sole pathogen in 8% (17/199) of diarrhoeic stool specimens. Other organisms were detected along with rotavirus in 11% of faecal specimens. A third of the children with rotavirus diarrhoea, according to Vesikari score, had severe illness. The top four rotavirus genotypes were G9P (28%), G1P (19%), G2P (14%) and G8P (8%). In the multivariate model, the practice of ‘drawing drinking water by dipping a pot in the storage vessel’ [adjusted odds ratio (aOR) 2·21, 95% confidence interval (CI) 1·03–4·74, P = 0·041], and ‘children aged ⩽6 months with non-exclusive breastfeeding’ (aOR 2·07, 95% CI 1·1–3·82, P = 0·024) had twice the odds of having diarrhoea. Incidence of rotavirus diarrhoea was 24/100 child-years in children aged >6–18 months, 19/100 child-years in children aged >18–24 months and 5/100 child-years in those aged ⩽6 months. Results have translational implications for future interventions including vaccine development.
To assess the role of sociodemographic and nutritional factors in the incidence of births affected by neural tube defects (NTD) in the North Indian population.
Government hospitals of Delhi, India.
Subjects comprised 284 mothers of NTD children (cases) and 568 mothers of healthy children (controls).
Significant differences were found between case and control mothers with respect to maternal age (P = 0·005), type of drinking water (P = 0·03) and consumption of milk (P = 0·01). Univariate and multivariate analysis suggested an association of unpasteurized milk use, low consumption of vegetables, low consumption of fruits and vegetarian dietary habits with NTD births. Further, variation in the risk factors for upper and lower NTD types was also observed, pointing towards phenotypic heterogeneity in the aetiology.
The results of the present study suggest an increased risk of NTD infants in mothers with low consumption of vegetables, fruits and milk and having vegetarian dietary habits. So, in order to reduce these devastating birth defects in future offspring, better nutritional care should be provided to mothers by suggesting dietary modifications and augmenting additional micronutrient supplementation during the periconceptional period.
Bidirectional reflectance of a surface is defined as the ratio of the scattered radiation at the detector to the incident irradiance as a function of geometry. Accurate knowledge of the bidirectional reflection function for layers composed of discrete, randomly positioned scattering particles is essential for many remote sensing, engineering, and biophysical applications, as well as for different areas of astrophysics. Computations of bidirectional reflection functions for plane parallel particulate layers are usually reduced to solving the radiative transfer equation by the existing techniques. In this work we present our laboratory data on bidirectional reflectance versus phase angle for two sample sizes of alumina, 0.3 and 1 μm, for the He–Ne laser at wavelengths of 632.8 nm (red) and 543.5 nm (green). The nature of the phase curves of the asteroids depends on the parameters like particle size, composition, porosity, roughness, etc. In the present study we analyze data which are being generated using a single scattering phase function, that is, Mie theory of treating particles as a compact sphere. The well-known Hapke formula, along with different particle phase functions such as Mie and Henyey–Greenstein, will be used to model the laboratory data obtained at the asteroid laboratory of Assam University.
To assess whether nutritional deficiency increases susceptibility to arsenic-related health effects.
Assessment of nutrition was based on a 24 h recall method of all dietary constituents.
Epidemiological cross-sectional study was conducted in an arsenic-endemic area of West Bengal with groundwater arsenic contamination.
The study was composed of two groups – Group 1 (cases, n 108) exhibiting skin lesions and Group 2 (exposed controls, n 100) not exhibiting skin lesions – age- and sex-matched and having similar arsenic exposure through drinking water and arsenic levels in urine and hair.
Both groups belonged to low socio-economic strata (Group 1 significantly poorer, P < 0·01) and had low BMI (prevalence of BMI < 18·5 kg/m2: in 38 % in Group 1 and 27 % in Group 2). Energy intake was below the Recommended Daily Allowance (set by the Indian Council of Medical Research) in males and females in both groups. Increased risk of arsenical skin lesions was found for those in the lowest quintile of protein intake (v. highest quintile: OR = 4·60, 95 % CI 1·36, 15·50 in males; OR = 5·62, 95 % CI 1·19, 34·57 in females). Significantly lower intakes of energy, protein, thiamin, niacin, Mg, Zn and choline were observed in both males and females of Group 1 compared with Group 2. Significantly lower intakes of carbohydrate, riboflavin, niacin and Cu were also observed in female cases with skin lesions compared with non-cases.
Deficiencies of Zn, Mg and Cu, in addition to protein, B vitamins and choline, are found to be associated with arsenical skin lesions in West Bengal.
We demonstrate that one can detect minuscule amounts of hydrogen diffusion out of a-Si:H under illumination at room temperature, by monitoring the changes in the Raman spectrum of amorphous tungsten oxide as a function of illumination. The Staebler-Wronski effect, the light-induce creation of metastable defects in hydrogenated amorphous silicon (a-Si:H), has been one of the major problems that has limited the performance of such devices as solar cells. Recently, Branz suggested the hydrogen collision model that can explain many aspects of the Staebler-Wronski effect. One of the main predictions of this model is that the photogenerated mobile hydrogen atoms can move a long distance at room temperature. However, light-induced hydrogen motion in a-Si:H has not been experimentally observed at room temperature. We utilized the high sensitivity of the Raman spectrum of electrochromic a-WO3 to hydrogen insertion to probe the long-range motion of hydrogen at room temperature. We deposited a thin (200 nm) layer of a-WO3 on top of a-Si:H, and under illumination, a change in the Raman spectrum was detected. By comparing the Raman signal changes with those for control experiments where hydrogen is electrochemically inserted into a-WO3, we can estimate semiquantitatively the amount of hydrogen that diffuses out of the a-Si:H layer.
The electronic structure of CeAg2Ge2 single crystal has been investigated by using resonant valence band photoemission and angle-resolved photoemission spectroscopy at different photon energies. Resonant photoemission has been observed near the 4d threshold of Ce at 121 eV. The constant initial state spectra show two photoemission features having 4f character near the Fermi level that exhibits Fano-like sharp resonance profile. Experimental energy bands have been mapped from the normal-emission photoelectron spectra of CeAg2Ge2 (001) surface along the Γ–Z direction. Four photoemission features are observed to show the dispersion related to the Ce 4f states and the hybridized Ag 4d with Ge 4p states. The experimental spectra have been interpreted with the help of calculations based on full potential linear augmented plane wave method using density functional theory.
The electronic structure of Co (100 Å)/Cu (50 Å) bilayer film on Si(100) has been investigated using valence band photoemission at 50 eV. The aim is to understand the Co/Cu interface and the nature of intermixing in Co and Cu layers. The valence band of Co/Cu interface shows three features at −0.3, −1.17 and −1.9 eV binding energy. The experimental observations are explained with the help of calculations based on projected augmented wave pseudopotential method using density functional theory. The origin of −0.3 eV feature is mainly due to the Co 3d minority spin states while the features at −1.17 and −1.9 eV are due to the formation of Co and Co–Cu mixed nanoclusters at the interface.
We report on the results of our investigation of using porous Si to enhance the performance of crystalline silicon photovoltaic solar cells. Possible approaches include using the porous Si for (1) surface texturing to enhance light trapping, (2) front or back surface fields because of its wider bandgap, and (3) photon color conversion of blue light to longer wavelengths that have higher quantum efficiency in a Si solar cell. In our surface texturing study, a porous-Si-covered single-crystal Si wafer showed an integrated reflectance of only 1.4% at 500-nm wavelength compared to about 40% for a polished Si surface. For our solar cell study, we used a point-contact cell structure with diffused p+ and n+ point contacts on the back of the cell. This cell structure allows us to form the porous Si on the front surface after both the junction formation and the evaporation and alloying of metal contacts.
A Kaufman ion-beam source has been used to study the rehydrogenation and postdeposition hydrogenation of amorphous silicon. In the rehydrogenation study, hydrogen atoms were implanted into glow-discharge-deposited amorphous silicon materials in which the hydrogen content had been driven out by heating. In the posthydrogenation study, amorphous silicon samples with no hydrogen content detectable by infrared absorption and no photoconductivity were used as the starting material. These materials were deposited by thermal CVD, magnetron sputtering, or RF glow discharge.
Modified BaTiO3 ceramics are candidate materials for infrared sensors in nightvision equipment. Measurements of dielectric constants, dielectric losses, pyroelectric coefficient, and heat capacities as functions of temperature and frequency are performed. Crystallographic and grain size data are also presented. It is shown that additions of these impurities to BaTiO3 alters the temperature of phase transformations and, with it, dielectric and pyroelectric properties. The results of these measurements were compared with those of PZT and PbTiO3 ceramics, which are currently the favoredmaterials for uncooled detector arrays, as well as PbTiO3 and PZT thin films. It is concluded that these oxide ceramics offer the combination of preparative ease of property modification and show good performance at low impurity concentrations.
Calorimetric changes in a series of pure and doped single crystal and polycrystalline BaTiO3 were studied using differential scanning calorimetry over the temperature range of-110°C to 200°BC. The dopants, oxides of niobium and iron were varied from 0.5 to 8 mole percent, and strontium was varied from 5 to 35 mole percent. Endotherms were observed corresponding to three crystallographic transitions. The highest observed thermal transition corresponds to a tetragonal to cubic crystallographic transition and is also associated with the Curie temperature in these materals. Two additional endothermic transitions were also observed, an intermediatetemperature orthorhombic to tetragonal transition, and a low-temperature rhombohedral to orthorhombic transition. The three dopants decreased the crystallographic transition temperatures and Curie temperature as the dopant concentration was increased. X-ray diffraction was used to identify phases present and to determine the extent of solid solution. It is expected that these materials will display improved infrared detection as well as opto-electronic properties.
Ferroelectric relaxor thin films of lead lanthanide zirconate titanate (PLZT) (9.5/ 65/35) have been deposited by the laser ablation technique onto metallized silicon and lanthanum aluminate substrates. The dielectric and pyroelectric properties of PLZT films and their temperature dependencies have been investigated in some detail in an evaluation of their potential as prospective pyroelectric infrared (IR) detector materials. The temperature at which the dielectric constant of a PLZT film reaches its peak is different from that for the peak pyroelectric coefficient. A lower dielectric constant at which the pyroelectric peak appears contributes to a high figure of merit for PLZT films, so that it is competitive with its ceramic counterpart, as well as with Pb(Mg1/3Nb2/3)O3 (PMN) relaxor ferroelectric ceramic.
Over a 2-year period, 25 families comprising of 181 individuals of all ages were longitudinally observed for the excretion of Campylobacter species. Faecal samples were taken from all persons with diarrhoea. Specimens were also taken from apparently healthy individuals and from domestic animals living within the confines of the study families at monthly intervals.
The overall diarrhoea attack rate was 19 episodes per 100 person-years with peak incidence in the 1- to 4-year-old age group (76/100 person-years). Eight (11·5%) of the total episodes were campylobacter-associated and the overall rate of campylobacter positive diarrhoeal episodes were 2·2 per 100 person-years. Of the 1002 stool samples from healthy individuals 32 (3·2/100 samples) were positive for campylobacter. The organism was most frequently isolated from children under 1 year of age both during diarrhoeal episodes (11·5 per 100 person-years) and non-diarrhoeal (11·1 per 100 samples). Multiple infections in a family were rare. In 19·4% of the occasions one or more animals were campylobacter positive. However, only in 7·7% of these occasions was a human infection recorded within 1 month after the animal was found to be positive.
The study showed that the epidemiology of campylobacteriosis in this community was distinct compared to that observed in developed countries.
Fourteen strains of S. Typhi (n=13) and S. Paratyphi A (n=1) resistant to ciprofloxacin were compared with 30 ciprofloxacin decreased-susceptibility strains on the basis of qnr plasmid analysis, and nucleotide substitutions at gyrA, gyrB, parC and parE. In ciprofloxacin-resistant strains, five S. Typhi and a single S. Paratyphi A showed triple mutations in gyrA (Ser83→Phe, Asp87→Asn, Glu133→Gly) and a novel mutation outside the quinolone resistance determining region (QRDR) (Met52→Leu). Novel mutations were also discovered in an isolate (minimum inhibitory concentration 8 μg/ml) in gyrA gene Asp76→Asn and outside the QRDR Leu44→Ile. Out of 30 isolates with reduced susceptibility, single mutation was found in 12 strains only. Genes encoding qnr plasmid (qnr A, qnr B, AAC1-F) were not detected in ciprofloxacin-resistant or decreased-susceptibility strains. Antimicrobial surveillance coupled with molecular analysis of fluoroquinolone resistance is warranted for reconfirming novel and established molecular patterns of resistance, which is quintessential for reappraisal of enteric fever therapeutics.
One hundred and six patients suffering from severe
dehydrating diarrhoea were studied of
whom 36 patients were positive for Vibrio cholerae.
Out of 36, 15 were positive for V. cholerae
O1, 10 for V. cholerae O139 and 11 for V.
cholerae non-O1 non-O139. O1 and O139 were
positive for the 301-bp ctxA amplicon and 471-bp
tcpA amplicon indicating that the strains
possessed toxigenic capability whereas no non-O1 non-O139
strain possessed ctxA or tcpA
genes. Post-admission severity of purging and amount of
ORS required were less in the
V. cholerae non-O1 non-O139 group
(P<0·05) compared to the V.
cholerae O1 and O139
groups. It appears from this study that a cholera-like
clinical condition can be caused in the
absence of CT as exemplified by strains of non-O1 non-O139.
It has been suggested recently that the prevalence of autistic disorder may be rising. No prevalence study specifically among learning disabled children exists and so this study was prompted.
Method. 767 children with a learning disability who attended 16 different special schools in the Grampian region of north-east Scotland were studied for a diagnosis of autistic disorder according to the DSM–III–R criteria. The study was conducted in three stages. In the first screening stage, a questionnaire was completed for each child by their teachers. In the second stage, teachers completed another questionnaire based on DSM–III–R criteria for autistic disorder. A final diagnosis was made on the basis of examination and information gathered from the questionnaires.
Questionnaires were completed for 634 (82.7%) children. 14.3% of children with a learning disability fulfilled the diagnostic criteria for autistic disorder. There was a male: female ratio of 3:1. This gave a 9 per 10 000 minimum prevalence of autistic disorder among all school-age children in the Grampian region. There was a higher prevalence of autistic disorder in the cities compared with rural areas. The prevalence did not change with age but increased with decreasing IQ.
The chemical diffusion coefficients of lithium ions in LixWO3 films were investigated as a function of lithium concentration and film porosity. Thin films were deposited with different porosities by thermal evaporation of WO3 powder in various partial water pressures. Our results indicate that diffusion coefficients increase with film porosity and decrease with increasing lithium concentration. Large diffusion coefficients that were found for small lithium concentrations appear to be due to the contribution of protons generated from ion exchange reactions between lithium and water incorporated in the film. Simultaneous electrical and in situ optical measurements were carried out to study the effect of porosity on the electrochromic properties of LixWO3. The coloring efficiency of porous WO3 films increases by approximately 70% when deposited in partial water pressure of 10−4 Torr, but decreases with further increments in water pressure.
Various factors affecting the coloring and bleaching processes of LixWO3 films have been studied. The rate of the coloring process is limited by the decreasing electromotive force in the LixWO3 film and by the components of the series circuit resistance, including the electrolyte resistance and the diffusion impedance within the film. The bleaching process in a thick film is limited by either the space charge or by the diffusion impedance, depending on the experimental conditions. A more complete and quantitative model of the coloring/bleaching process has been developed and shows good agreement with experimental results. Our analysis also indicates that the lithium concentration value of x near the LixWO3/electrolyte interface can greatly exceed its reversible limit during the coloring process, even though the average x value within the film remains much lower than the reversible limit. This phenomenon may introduce some irreversible structural changes in the film, which in turn may constitute one of the film's degradation mechanisms.