7,708 research outputs found
Effects of Trypanosoma brucei and Heligmosomoides bakeri infections on water consumption of lactating albino mice and the viability of their pre-weaned offspring
The effects of single and/or concurrent H. bakeri and T. brucei infections on water consumption of lactating and non-lactating mice were investigated. Pregnant mice were grouped into four (A, B, C and D) comprising of six animals per group. Groups A, B and C were either infected with H. bakeri or T. brucei alone or with both parasites together. Group D served as pregnant uninfected control while a different group (E) was used as non-pregnant and uninfected control. Packed cell volumes (PCV), faecal egg counts (FEC), worm burden and water consumption of the mice were determined. Mean live-weights of surviving offspring and their numbers were recorded. Infected animals had lower PCV compared to the controls. However, lactating mice infected with both parasites had the least PCV. Mortalities occurred in the dualinfected groups. Worm burden and FEC of mice with concurrent infections were significantly higher than that of the H. bakeri-only infected mice. Lactating mice consumed significantly more water than non-lactating mice . Uninfected and H. bakeri-only infected mice had heavier, healthy-looking and greater numbers of pups than their conjointly-infected counterparts that had fewer wrinkled-bodied pups with more early-mortalities following parturition. Drawing from these results, it is therefore necessary to promptly control diseases in pregnant and lactating animals and provide water adlibitum to lactating animals. Keywords: Water consumption, Lactating mice, Trypanosoma brucei, Heligmosomoides bakeri, concurrent infectio
An electron microscopy study of the effect of Ce on plasma sprayed bronze coatings
The Cu-Al eutectoid alloy is an excellent material for mould due to its superior low friction. The conventional sand casting technique, however, is not feasible to fabricate high Al bronze because of high hardness and brittleness. Plasma arc spray has been used to produce high Al/Fe bronze coatings for mould. The inherent impurities such as H, O, N, S during the spray, however, may affect the coating's mechanical strength. One approach is to utilise the active rare earth Ce to clean up these impurities. The study is to investigate the effect of Ce on the microstructure, which has few reported in the literature<br/
0-π transition characteristic of the Josephson current in a carbon nanotube quantum dot
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Legacy Effect of Long-Term Elevated CO2 and Warming on Soil Properties Controls Soil Organic Matter Decomposition
Plant litter quality is one of the key factors that control soil organic matter (SOM) decomposition. Under climate change, although significant change in litter quality has been intensively reported, the effect of litter quality change on SOM decomposition is poorly understood. This limits our ability to model the dynamics of soil carbon under climate change. To determine the effect of litter quality and soil property change on SOM decomposition, we performed a controlled, reciprocal transplant and litter decomposition experiments. The soils and plant litters were collected from a long-term field experiment, where four treatments were designed, including: (1) the control without warming at ambient CO2; (2) elevated atmospheric CO2 up to 500 ppm (C); (3) warming plant canopy by 2 degrees C (T); (4) elevated CO2 plus warming (CT). We found that elevated CO2 and warming altered the litter quality significantly in terms of macronutrients' content and their stoichiometry. Elevated CO2 decreased the concentration of N in rice and wheat straw, while warming decreased the concentration of N and K in wheat straw. However, the change in plant litter quality did not lead to a shift in SOM decomposition. On the contrary, the legacy effect of long-term elevated CO2 and warming on soil properties dominated the decomposition rate of SOM. Elevated atmospheric CO2 suppressed SOM decomposition mainly by increasing phosphorous availability and lowering the soil C/N, fungi/bacteria ratio, and N-acetyl-glucosaminidase activity, while warming or elevated CO2 plus warming had no effect on SOM decomposition. Our results demonstrated that the changes in soil property other than litter quality control the decomposition of SOM under climate change, and soil property change in respond to climate change should be considered in model developing to predict terrestrial soil carbon dynamics under elevated atmospheric CO2 and warming
Ca isotope constraints on chemical weathering processes: Evidence from headwater in the Changjiang River, China
This study aims to clarify the relationship between chemical weathering of rocks and the carbon budget of rivers and better understand the weathering mechanisms of plateau watersheds. We chose to study the Jinsha River, which originates from the Tibetan Plateau and also is in the upper reaches of the Changjiang River. Analysis of hydrochemistry, radiogenic strontium isotope and stable calcium isotopes were conducted of the Jinsha River water samples, which were collected along its mainstream and main tributaries in the summer. The results show that the water chemistry of the mainstream waters is dominated by evaporite weathering, which have low 87Sr/86Sr values (0.7098–0.7108) and wide range of Sr contents (2.70–9.35 μmol/L). In contrast, tributaries of the Jinsha River have higher 87Sr/86Sr (0.7090–0.7157) and lower Sr contents (∼1 μmol/L). Moreover, the Ca isotopic compositions in the mainstream (0.87–1.11‰) are heavier than the tributaries (0.68–0.88‰) and could not be fully explained by the conventional mixing of different sources. We suggest that secondary carbonate precipitation fractionates Ca isotopes in the Jinsha River, and fractionation factors are between 0.99935 and 0.99963. At least 66% of Ca was removed in the mainstream of the Jinsha River through secondary mineral precipitation, and the average value is ∼35% in the tributaries. The results highlight that evaporite weathering results in more carbonate precipitation influencing Ca transportation and cycling in the riverine system constrained by stable Ca isotopic compositions and water chemistry
Spatially configuring wrinkle pattern and multiscale surface evolution with structural confinement
© 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Surface elastic instabilities, such as wrinkling and creasing, can enable a convenient strategy to impart reversible patterned topography to a surface. Here the classic system of a stiff layer on a soft substrate is focused, which famously produces parallel harmonic wrinkles at modest uniaxial compression that period-double repeatedly at higher compressions and ultimately evolve into deep folds and creases. By introducing micrometer-scale planar Bravais lattice holes to spatially pattern the substrate, these instabilities are guided into a wide variety of different patterns, including wrinkling in parallel bands and star shape bands, and radically reduce the threshold compression. The experimental patterns and thresholds are enabled to understand by considering a simple plane-strain model for the patterned substrate-deformation, decorated by wrinkling on the stiff surface layer. The experiments also show localized wrinkle-crease transitions at modest compression, yielding a hierarchical surface with different generations of instability mixed together. By varying the geometrical inputs, control over the stepwise evolution of surface morphologies is demonstrated. These results demonstrate considerable control over both the patterns and threshold of the surface elastic instabilities, and have relevance to many emerging applications of morphing surfaces, including in wearable/flexible electronics, biomedical systems, and optical devices
PHYSICAL PERFORMANCE AND BODY COMPOSITION IN MAINTENANCE HEMODIALYSIS (MHD) PATIENTS
BackgroundMHD patients (pts) often display protein-energy wasting, sarcopenia & diminished physical performance. This study was undertaken to assess the relationship between body composition & physical performance in MHD pts.MethodsBody composition, assessed by dual energy x-ray absorptiometry and body mass index (BMI), were compared to 3 measures of physical performance: 6-minute walking distance (6-MW), sit-to-stand testing and stair climb. 52 clinically stable MHD pts (≥6 mo) and 21 matched normal controls were examined in this ongoing study.ResultsPts were 53±13SD yrs, 33% female; 38% diabetic; dialysis vintage was 62±52 months. Normals were 52 years and 43% female. MHD pts had higher % body fat than Normals. 6-MW and sit to stand cycles were much lower in MHD men and women than in Normal men and women. 6MW in MHD and Normals were 445 vs 630 meters, respectively (p<.001). In men but not women, time to climb 22 stairs was greater in MHD pts then in Normals (p=.03). Unadjusted analyses in MHD indicated that 6-MW distance correlated negatively with lean body mass index (LBMI, kg of LBM/m2; r=-0.37; p<0.01) and % body fat (r=-0.33; p= 0.02); stair climb time correlated negatively with lean leg mass (r=-0.32, p=0.03) and total leg mass (r=-0.29, p=0.045).). Sit-to-stand did not correlate with any body composition measure. 6-MW adjusted for age and gender correlated negatively with LBMI (r=-0.29; p=0.04).There were no associations between BMI (range, 19.8-44.2 kg/m2) and physical performance.ConclusionsThese findings indicate that adult MHD pts had a higher % body fat. Measures of physical performance were markedly reduced in MHD pts as compared to Normals. Physical performance in MHD, measured especially by 6-MW, correlated negatively with some measures of body composition, particularly with LBMI
Measurement of the substitutional nitrogen activation energy in diamond films
We show that the electrical properties of nitrogen-doped nominally undoped polycrystalline chemical vapor deposited diamond films are modified by post-deposition heating in an oxidizing atmosphere. We found that the first heating cycle in air in the temperature range of 300-673 K decreased the graphitization content still present in the diamond surface and that after the second heating cycle the electrical resistance versus temperature curves became stabilized. Using a flow of argon with residues of oxygen over the surface of the sample during the heating cycles, the stabilization of the resistance-temperature dependence also occurred but only after the fourth heating cycle. The results suggest the existence of an oxidation mechanism of the nondiamond carbon atoms present at the diamond surface. After stabilization, the deep donor ionization energy was found to be E-d= 1.62+/-0.02 eV. All results brought together strongly suggest that this level is due to single nitrogen atoms that occupy substitutional lattice sites in diamond. (C) 1998 American Institute of Physics. [S0003-6951(98)01632-5].73681281
Health-state utilities in a prisoner population : a cross-sectional survey
Background: Health-state utilities for prisoners have not been described.
Methods: We used data from a 1996 cross-sectional survey of Australian prisoners (n = 734).
Respondent-level SF-36 data was transformed into utility scores by both the SF-6D and Nichol's
method. Socio-demographic and clinical predictors of SF-6D utility were assessed in univariate
analyses and a multivariate general linear model.
Results: The overall mean SF-6D utility was 0.725 (SD 0.119). When subdivided by various medical
conditions, prisoner SF-6D utilities ranged from 0.620 for angina to 0.764 for those with none/mild
depressive symptoms. Utilities derived by the Nichol's method were higher than SF-6D scores,
often by more than 0.1. In multivariate analysis, significant independent predictors of worse utility
included female gender, increasing age, increasing number of comorbidities and more severe
depressive symptoms.
Conclusion: The utilities presented may prove useful for future economic and decision models
evaluating prison-based health programs
The long noncoding RNA MALAT1 promotes tumor-driven angiogenesis by up-regulating pro-angiogenic gene expression
Neuroblastoma is the most common solid tumor during early childhood. One of the key features of neuroblastoma is extensive tumor-driven angiogenesis due to hypoxia. However, the mechanism through which neuroblastoma cells drive angiogenesis is poorly understood. Here we show that the long noncoding RNA MALAT1 was upregulated in human neuroblastoma cell lines under hypoxic conditions. Conditioned media from neuroblastoma cells transfected with small interfering RNAs (siRNA) targeting MALAT1, compared with conditioned media from neuroblastoma cells transfected with control siRNAs, induced significantly less endothelial cell migration, invasion and vasculature formation. Microarray-based differential gene expression analysis showed that one of the genes most significantly downregulated following MALAT1 suppression in human neuroblastoma cells under hypoxic conditions was fibroblast growth factor 2 (FGF2). RT-PCR and immunoblot analyses confirmed that MALAT1 suppression reduced FGF2 expression, and Enzyme-Linked Immunosorbent Assays revealed that transfection with MALAT1 siRNAs reduced FGF2 protein secretion from neuroblastoma cells. Importantly, addition of recombinant FGF2 protein to the cell culture media reversed the effects of MALAT1 siRNA on vasculature formation. Taken together, our data suggest that up-regulation of MALAT1 expression in human neuroblastoma cells under hypoxic conditions increases FGF2 expression and promotes vasculature formation, and therefore plays an important role in tumor-driven angiogenesis
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