292 research outputs found

    Risk factors for highly pathogenic avian influenza in commercial layer chicken farms in Bangladesh During 2011

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    postprintA case control study was conducted during 2011 involved 90 randomly selected commercial layer farms infected with highly pathogenic avian influenza type A subtype H5N1 (HPAI) and 175 control farms randomly selected from within 5km of infected farms. A questionnaire was designed to obtain information about potential risk factors for contracting HPAI and was administered to farm owners or managers. Logistic regression analyses were conducted to identify significant risk factors. A total of 20/43 risk factors for contracting HPAI were identified after univariable logistic regression analysis. A multivariable logistic regression model was derived by forward stepwise selection. Both unmatched and matched analyses were done. The key risk factors identified were numbers of staff, frequency of veterinary visits, presence of village chickens roaming on the farm and staff trading birds. Aggregating these findings with those from other studies resulted in a list of 16 key risk factors identified in Bangladesh. Most of these related to biosecurity. It is considered feasible for Bangladesh to achieve a very low incidence of HPAI. Using the cumulative list of risk factors to enhance biosecurity pertaining to commercial farms would facilitate this objective. Key words: Avian influenza; case-control study; logistic regression; risk factors, observational studies

    Risk factors for highly pathogenic avian influenza in commercial layer chicken farms in Bangladesh During 2011

    Get PDF
    A case control study was conducted during 2011 involved 90 randomly selected commercial layer farms infected with highly pathogenic avian influenza type A subtype H5N1 (HPAI) and 175 control farms randomly selected from within 5km of infected farms. A questionnaire was designed to obtain information about potential risk factors for contracting HPAI and was administered to farm owners or managers. Logistic regression analyses were conducted to identify significant risk factors. A total of 20/43 risk factors for contracting HPAI were identified after univariable logistic regression analysis. A multivariable logistic regression model was derived by forward stepwise selection. Both unmatched and matched analyses were done. The key risk factors identified were numbers of staff, frequency of veterinary visits, presence of village chickens roaming on the farm and staff trading birds. Aggregating these findings with those from other studies resulted in a list of 16 key risk factors identified in Bangladesh. Most of these related to biosecurity. It is considered feasible for Bangladesh to achieve a very low incidence of HPAI. Using the cumulative list of risk factors to enhance biosecurity pertaining to commercial farms would facilitate this objective. Key words: Avian influenza; case-control study; logistic regression; risk factors, observational studies

    Selective Spin-State Switch and Metal-Insulator Transition in \boldmath GdBaCo2O5.5\rm GdBaCo_2O_{5.5}

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    Ultra-high resolution synchrotron diffraction data for GdBaCo2O5.5\rm GdBaCo_2O_{5.5} throw new light on the metal-insulator transition of Co3+^{3+} Ba-cobaltites. An anomalous expansion of CoO6_6 octahedra is observed at the phase transition on heating, while CoO5_5 pyramids show the normal shrinking at the closing of the gap. The insulator-to-metal transition is attributed to a sudden excitation of some electrons in the octahedra (t2g6t_{2g}^6 state) into the Co ege_g band (final t2g4eg2t_{2g}^4e_g^2 state). The t2g5eg1t_{2g}^5e_g^1 state in the pyramids does not change and the structural study also rules out a d3x2−r2/d3y2−r2d_{3x^2-r^2}/d_{3y^2-r^2} orbital ordering at TMIT_{MI}.Comment: Phys. Rev. B (to appear

    Evidence for orbital ordering in LaCoO3

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    We present powder and single crystal X-ray diffraction data as evidence for a monoclinic distortion in the low spin (S=0) and intermediate spin state (S=1) of LaCoO3. The alternation of short and long bonds in the ab plane indicates the presence of eg orbital ordering induced by a cooperative Jahn-Teller distortion. We observe an increase of the Jahn-Teller distortion with temperature in agreement with a thermally activated behavior of the Co3+ ions from a low-spin ground state to an intermediate-spin excited state.Comment: Accepted to Phys. Rev.

    Evidence for a Low-Spin to Intermediate-Spin State Transition in LaCoO3

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    We present measurements of the magnetic susceptibility and of the thermal expansion of a LaCoO3_3 single crystal. Both quantities show a strongly anomalous temperature dependence. Our data are consistently described in terms of a spin-state transition of the Co3+^{3+} ions with increasing temperature from a low-spin ground state to an intermediate-spin state without (100K - 500K) and with (>500K) orbital degeneracy. We attribute the lack of orbital degeneracy up to 500K to (probably local) Jahn-Teller distortions of the CoO6_6 octahedra. A strong reduction or disappearance of the Jahn-Teller distortions seems to arise from the insulator-to-metal transition around 500 K.Comment: an error in the scaling factor of Eq.(4) and consequently 2 values of table I have been corrected. The conclusions of the paper remain unchanged. See also: C. Zobel et al. Phys. Rev. B 71, 019902 (2005) and J. Baier et al. Phys. Rev. B 71, 014443 (2005

    The influence of the rare earth ions radii on the Low Spin to Intermediate Spin state transition in lanthanide cobaltite perovskites: LaCoO3 vs. HoCoO3

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    We present first principles LDA+U calculations of electronic structure and magnetic state for LaCoO3 and HoCoO3. Low Spin to Intermediate Spin state transition was found in our calculations using experimental crystallographic data for both materials with a much higher transition temperature for HoCoO3, which agrees well with the experimental estimations. Low Spin state t6e0 (non-magnetic) to Intermediate Spin state t5e1 (magnetic) transition of Co(3+) ions happens due to the competition between crystal field t_2g-e_g splitting and effective exchange interaction between 3dd spin-orbitals. We show that the difference in crystal structure parameters for HoCoO3 and LaCoO3 due to the smaller ionic radius of Ho ion comparing with La ion results in stronger crystal field splitting for HoCoO3 (0.09 eV ~ 1000 K larger than for LaCoO3) and hence tip the balance between the Low Spin and Intermediate Spin states to the non-magnetic solution in HoCoO3.Comment: 13 pages, 6 figure

    The effect of urine concentration and pH on the growth of Escherichia coli in canine urine in vitro

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    Background: Lower urinary tract infections are common in dogs, and Escherichia coli is the most common bacterial pathogen isolated. The literature has conflicting evidence regarding the inhibitory effects of urine concentration and pH on E. coli growth. Hypothesis/Objectives: To determine the effect of different pH and urine concentrations on E. coli growth in vitro. Animals: Voided urine samples from 10 apparently healthy spayed female dogs were used. Methods: A matrix of 9 urine specific gravity (USG; 1.010, 1.020, and 1.030) and pH (5.5, 7.0, and 8.5) combinations was prepared by diluting and titrating filtered voided urine samples. Three E. coli isolates were obtained from urine of female dogs with signs of lower urinary tract infection and cultured at different urine pH and USG combinations in wells of a microtiter plate. The number of E. coli colony‐forming units (CFU) per mL of urine was calculated after aerobic incubation of the urine at 37°C for 18 hours, and statistically compared. Results: Significant differences were identified in the mean log CFU/mL among different combinations of pH and USG. The lowest log CFU/mL were observed in alkaline concentrated urine (pH 8.5 and USG 1.030). Conclusions and Clinical Importance: Escherichia coli in vitro growth was higher in neutral to acidic and diluted urine compared to alkaline and concentrated urine. The impact of non‐alkalizing diluting diets on the incidence of E. coli lower urinary tract infections should be further explored

    Recommendations to encourage participation of individuals from diverse backgrounds in psychiatric genetic studies

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    We present innovative research practices in psychiatric genetic studies to ensure representation of individuals from diverse ancestry, sex assigned at birth, gender identity, age, body shape and size, and socioeconomic backgrounds. Due to histories of inappropriate and harmful practices against marginalized groups in both psychiatry and genetics, people of certain identities may be hesitant to participate in research studies. Yet their participation is essential to ensure diverse representation, as it is incorrect to assume that the same genetic and environmental factors influence the risk for various psychiatric disorders across all demographic groups. We present approaches developed as part of the Eating Disorders Genetics Initiative (EDGI), a study that required tailored approaches to recruit diverse populations across many countries. Considerations include research priorities and design, recruitment and study branding, transparency, and community investment and ownership. Ensuring representation in participants is costly and funders need to provide adequate support to achieve diversity in recruitment in prime awards, not just as supplemental afterthoughts. The need for diverse samples in genetic studies is critical to minimize the risk of perpetuating health disparities in psychiatry and other health research. Although the EDGI strategies were designed specifically to attract and enroll individuals with eating disorders, our approach is broadly applicable across psychiatry and other fields
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