904 research outputs found

    Field decomposition of transgenic Bt maize residue and the impact on non-target soil invertebrates

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    Genetically modified Bacillus thuringiensis Berliner (Bt) maize (Zea mays L.) expressing Cry toxins against various target pests is now grown on more than 16 million hectares worldwide, but its potential effects on the soil ecosystem need to be further investigated. In an 8-month field study, we investigated the effects of Bt maize expressing the Cry1Ab protein on both the soil community and maize residue decomposition. We used litterbags with three different mesh sizes (20, 125, and 5,000μm) to investigate potential effects of different soil organism groups on the decomposition processes. Litterbags were incorporated into the soil in fall into a field that had previously been planted with non-Bt maize and subsamples were removed monthly. The dry weight of the remaining residue was measured for all bags. Bt and non-Bt maize decomposed similarly in large mesh bags, which allowed the whole soil organism community to enter and interact with each other. In contrast, Bt maize decomposed significantly faster than non-Bt maize at some sample dates in winter in bags with small and medium mesh sizes. At the end of the experiment in late spring, however, there was no significant difference in the amount of maize plant residues remaining for any of these three mesh sizes. Additionally, soil organisms from bags with the largest mesh size were identified. The most frequent taxa extracted were collembolans (Isotomidae, Tullbergiidae, Entomobryidae), mites (Gamasina, Oribatida), and annelids (Enchytraeidae). Three of these taxa were extracted in higher numbers from non-Bt than Bt residue (Tullbergiidae, Gamasina, Enchytraeidae), while there was no difference in the number of individuals extracted for the remaining three taxa. Our results do not show major changes in the decomposition of Bt maize residue and in the composition of the soil organism community. However, further studies are needed that assess the impact of the continuous release of Cry1Ab via root exudates and plant biomass on the soil ecosyste

    A purely geometric distance to the binary star Atlas, a member of the Pleiades

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    We present radial velocity and new interferometric measurements of the double star Atlas, which permit, with the addition of published interferometric data, to precisely derive the orbital parameters of the binary system and the masses of the components. The derived semi-major axis, compared with its measured angular size, allows to determine a distance to Atlas of 132+-4 pc in a purely geometrical way. Under the assumption that the location of Atlas is representative of the average distance of the cluster, we confirm the distance value generally obtained through main sequence fitting, in contradiction with the early Hipparcos result (118.3+-3.5 pc).Comment: 5 pages, 3 figures, accepted for publication in A&A Letter

    Social integration of people with a migration background in Swiss sport clubs: A cross-level analysis

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    Sport clubs are considered an ideal setting for the social integration of people with a migration background (PMB). However, they can also be a place of social closure practices, where assimilative ideas and ethnic boundaries are present. Besides the individual characteristics of the members, adequate club organizational structures are relevant for preventing social closure and facilitating social integration. Thus, the role of organizational structures for social integration might differ between natives and PMB. Based on data from 42 Swiss sport clubs and 780 sport club members, with and without a migration background, we analyzed individual (migration background, membership biography) and structural factors (situational, club goals, club culture) using multilevel models and tested cross-level interactions between structural variables and migration background. The results reveal that membership biography (e.g. membership duration and volunteering) and migration background are relevant for social integration. The estimated cross-level effects reveal that, unlike for natives and second-generation PMB, structural conditions are especially relevant for first-generation PMB. For example, social integration increases with a higher proportion of PMB in the club or a less assimilative club culture

    Normative Findings for Periocular Anthropometric Measurements among Chinese Young Adults in Hong Kong

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    Measurement of periocular structures is of value in several clinical specialties including ophthalmology, optometry, medical and clinical genetics, oculoplastic surgery, and traumatology. Therefore we aimed to determine the periocular anthropometric norms for Chinese young adults using a noninvasive 3D stereophotography system. Craniofacial images using the 3dMDface system were acquired for 103 Chinese subjects (51 males and 52 females) between the ages of 18 and 35 years. Anthropometric landmarks were identified on these digital images according to standard definitions, and linear distances between these landmarks were calculated. It was found that ocular measurements were significantly larger in Chinese males than females for intercanthal width, biocular width, and eye fissure lengths. No gender differences were found in the eye fissure height and the canthal index which ranged between 43 and 44. Both right and left eye fissure height-length ratios were significantly larger in females. This is the first study to employ 3D stereophotogrammetry to create a database of anthropometric normative data for periocular measurements. These data would be useful for clinical interpretation of periocular pathology and serve as reference values when planning aesthetic and posttraumatic surgical interventions

    Estimating carbon dioxide residence time scales through noble gas and stable isotope diffusion profiles

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    The study of natural carbon dioxide reservoirs provides fundamental insight into processes involved in carbon capture and storage. However, the calculations of process rates such as dissolution of CO2 into formation water remain uncertain due to indirectly determined ages of the CO2 influx. The proposed ages for the Bravo Dome gas field in New Mexico, USA, vary from 56 ka to 1.5 Ma. Here we demonstrate that residence times can be estimated from simple modeling of noble gas and stable isotope diffusion profiles from the gas-water contact through the gas column. The Bravo Dome gas field shows a gradient in noble gas concentrations and isotopic ratios from east to west across the 70-km-wide field. A mantle-like end member with a 3He/4He (R/RA) ratio of up to 4.7 is found in the west in contrast to a groundwater end member with high concentrations of air- and crustal-derived noble gases in the east. The air- and crustal-derived noble gases decrease gradually toward the west. Stable isotope compositions (C and O) also vary across the field. Diffusion modeling of He, Ne, Ar, Kr, Xe, and δ13C data yield residence times for the CO2 between 14.1 ± 0.2 ka and 16.9 +1.1/–0.5 ka. This is far less than the previous estimates of 1.2–1.5 Ma based on apatite (U-Th)/He thermochronology, leading to a dissolution rate of 29,900 +11,800/–10,700 t/a to 35,900 ± 12,300 t/a, implying that 28% of the total emplaced CO2 dissolved. This new method can be applied to a wide variety of gas fields with variation in the concentration of groundwater-derived noble gases and allow a better assessment of the time scale of other diffusive fluid-fluid interactions

    What does your neighbourhood say about you? : a study of life expectancy in 1.3 million Swiss neighbourhoods

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    BACKGROUND: Switzerland had the highest life expectancy at 82.8 years among the Organisation for Economic Co-operation and Development (OECD) countries in 2011. Geographical variation of life expectancy and its relation to the socioeconomic position of neighbourhoods are, however, not well understood. METHODS: We analysed the Swiss National Cohort, which linked the 2000 census with mortality records 2000-2008 to estimate life expectancy across neighbourhoods. A neighbourhood index of socioeconomic position (SEP) based on the median rent, education and occupation of household heads and crowding was calculated for 1.3 million overlapping neighbourhoods of 50 households. We used skew-normal regression models, including the index and additionally marital status, education, nationality, religion and occupation to calculate crude and adjusted estimates of life expectancy at age 30 years. RESULTS: Based on over 4.5 million individuals and over 400,000 deaths, estimates of life expectancy at age 30 in neighbourhoods ranged from 46.9 to 54.2 years in men and from 53.5 to 57.2 years in women. The correlation between life expectancy and neighbourhood SEP was strong (r=0.95 in men and r=0.94 women, both p values <0.0001). In a comparison of the lowest with the highest percentile of neighbourhood SEP, the crude difference in life expectancy from skew-normal regression was 4.5 years in men and 2.5 years in women. The corresponding adjusted differences were 2.8 and 1.9 years, respectively (all p values <0.0001). CONCLUSIONS: Although life expectancy is high in Switzerland, there is substantial geographical variation and life expectancy is strongly associated with the social standing of neighbourhoods

    Complement-Mediated Opsonic Activity in Normal and Infected Human Cerebrospinal Fluid: Early Response During Bacterial Meningitis

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    A local defense mechanism in bacterial meningitis was evaluated in humans by measuring complement-mediated opsonic activity (CMOA) in normal and infected cerebrospinal fluid (CSF) with a complement-dependent phagocytic bactericidal assay. CMOA was absent in normal untreated CSF and remained undetectable in 20 samples of CSF from patients with viral meningitis and five samples from patients with acute meningococcemia. In contrast, 15 of 27 samples of CSF from patients with acute bacterial meningitis had a measurable CMOA, which was correlated with protein concentrations (P < 0.01) and C4 hemolytic activity (P < 0.001) in the CSF. A favorable outcome of bacterial meningitis was associated with the presence of CMOA in CSF (P < 0.005). Recovery was also correlated with higher levels of C4 (P < 0.01) and C3 (P < 0.05) in CSF and with lower concentrations of microorganisms in the sample of CSF collected at the time of admission (P < 0.01). Thus, CMOA, although absent in normal CSF, can appear in CSF during acute bacterial meningitis, particularly in patients who recover completel

    Biochemical characterization of the Nocardia lactamdurans ACV synthetase

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    The L-δ-(α-aminoadipoyl)-L-cysteinyl-D-valine synthetase (ACVS) is a nonribosomal peptide synthetase (NRPS) that fulfills a crucial role in the synthesis of β-lactams. Although some of the enzymological aspects of this enzyme have been elucidated, its large size, at over 400 kDa, has hampered heterologous expression and stable purification attempts. Here we have successfully overexpressed the Nocardia lactamdurans ACVS in E. coli HM0079. The protein was purified to homogeneity and characterized for tripeptide formation with a focus on the substrate specificity of the three modules. The first L-α-aminoadipic acid-activating module is highly specific, whereas the modules for L-cysteine and L-valine are more promiscuous. Engineering of the first module of ACVS confirmed the strict specificity observed towards its substrate, which can be understood in terms of the non-canonical peptide bond position

    A systematic review of the survival and complication rates of zirconia-ceramic and metal-ceramic single crowns

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    Objectives: The aim of the present systematic review was to analyze the survival and complication rates of zirconia-based and metal-ceramic implant-supported single crowns (SCs). Materials and Methods: An electronic MEDLINE search complemented by manual searching was conducted to identify randomized controlled clinical trials, prospective cohort and retrospective case series on implant-supported SCs with a mean follow-up time of at least 3&nbsp;years. Patients had to have been clinically examined at the follow-up visit. Assessment of the identified studies and data extraction was performed independently by two reviewers. Failure and complication rates were analyzed using robust Poisson's regression models to obtain summary estimates of 5-year proportions. Results: The search provided 5,263 titles and 455 abstracts, full-text analysis was performed for 240 articles, resulting in 35 included studies on implant-supported crowns. Meta-analysis revealed an estimated 5-year survival rate of 98.3% (95% CI: 96.8–99.1) for metal-ceramic implant supported SCs (n&nbsp;=&nbsp;4,363) compared to 97.6% (95% CI: 94.3–99.0) for zirconia implant supported SCs (n&nbsp;=&nbsp;912). About 86.7% (95% CI: 80.7–91.0) of the metal-ceramic SCs (n&nbsp;=&nbsp;1,300) experienced no biological/technical complications over the entire observation period. The corresponding rate for zirconia SCs (n&nbsp;=&nbsp;76) was 83.8% (95% CI: 61.6–93.8). The biologic outcomes of the two types of crowns were similar; yet, zirconia SCs exhibited less aesthetic complications than metal-ceramics. The 5-year incidence of chipping of the veneering ceramic was similar between the material groups (2.9% metal-ceramic, 2.8% zirconia-ceramic). Significantly (p&nbsp;=&nbsp;0.001), more zirconia-ceramic implant SCs failed due to material fractures (2.1% vs. 0.2% metal-ceramic implant SCs). No studies on newer types of monolithic zirconia SCs fulfilled the simple inclusion criteria of 3&nbsp;years follow-up time and clinical examination of the present systematic review. Conclusion: Zirconia-ceramic implant-supported SCs are a valid treatment alternative to metal-ceramic SCs, with similar incidence of biological complications and less aesthetic problems. The amount of ceramic chipping was similar between the material groups; yet, significantly more zirconia crowns failed due to material fractures
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