437 research outputs found

    The KATRIN Experiment

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    The KArlsruhe TRitium Neutrino mass experiment, KATRIN, aims to search for the mass of the electron neutrino with a sensitivity of 0.2 eV/c^2 (90% C.L.) and a detection limit of 0.35 eV/c^2 (5 sigma). Both a positive or a negative result will have far reaching implications for cosmology and the standard model of particle physics and will give new input for astroparticle physics and cosmology. The major components of KATRIN are being set up at the Karlsruhe Institut of Technology in Karlsruhe, Germany, and test measurements of the individual components have started. Data taking with tritium is scheduled to start in 2012.Comment: 3 pages, 1 figure, proceedings of the TAUP 2009 International Conference on Topics in Astroparticle and Underground Physics, to be published in Journal of Physics, Conference Serie

    Ion Beam Tracking using Ultrasound Motion Detection

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    The KATRIN Pre-Spectrometer at reduced Filter Energy

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    The KArlsruhe TRItium Neutrino experiment, KATRIN, will determine the mass of the electron neutrino with a sensitivity of 0.2 eV (90% C.L.) via a measurement of the beta-spectrum of gaseous tritium near its endpoint of E_0 =18.57 keV. An ultra-low background of about b = 10 mHz is among the requirements to reach this sensitivity. In the KATRIN main beam-line two spectrometers of MAC-E filter type are used in a tandem configuration. This setup, however, produces a Penning trap which could lead to increased background. We have performed test measurements showing that the filter energy of the pre-spectrometer can be reduced by several keV in order to diminish this trap. These measurements were analyzed with the help of a complex computer simulation, modeling multiple electron reflections both from the detector and the photoelectric electron source used in our test setup.Comment: 22 pages, 12 figure

    Biologic variability of human foreskin fibroblasts in 2D and 3D culture: implications for a wound healing model

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    <p>Abstract</p> <p>Background</p> <p>The fibroblast-populated 3D collagen matrix is a model of tissue and healing which has been used since the 1980's. It was hypothesized that anchorage disruption of the collagen matrix would produce p53-dependent apoptosis in the embedded fibroblasts, but results of hypothesis testing were variant.</p> <p>Findings</p> <p>The response of p53 to anchorage disruption in 3D culture or to UV irradiation in 2D culture was influenced both by fibroblast strain and culture conditions. It also was determined that data scatter in a collagen matrix contraction assay was related to fibroblast strain and possibly to technical factors, such as cell culture technician and/or number of matrices utilized. Subsequent analysis suggested that phenotypic drift and/or inter-strain genetic variability may have been responsible for the data scatter. In addition, several technical factors were identified that may have contributed to the scatter.</p> <p>Conclusion</p> <p>Experimentation with human foreskin fibroblasts in both 2D and 3D culture can produce variant data. The underlying cause of the data scatter appears to be partially due to the biologic variability of the fibroblast.</p

    High rate of extrapair paternity in a human population demonstrates diversity in human reproductive strategies

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    Among nonhuman species, social monogamy is rarely accompanied by complete fidelity. Evolutionary theory predicts that the rate of extrapair paternity (EPP) should vary according to socioecological conditions. In humans, however, geneticists contend that EPP is negligible and relatively invariable. This conclusion is based on a limited set of studies, almost all of which describe European-descent groups. Using a novel, double-blind method designed in collaboration with a community of Himba pastoralists, we find that the rate of EPP in this population is 48%, with 70% of couples having at least one EPP child. Both men and women were very accurate at detecting cases of EPP. These data suggest that the range of variation in EPP across human populations is substantially greater than previously thought. We further show that a high rate of EPP can be accompanied by high paternity confidence, which highlights the importance of disaggregating EPP from the notion of “cuckoldry.

    Cancellous allogenic and autologous bone grafting ensure comparable tunnel filling results in two-staged revision ACL surgery

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    Objectives!#!Patients with recurrent instability after anterior cruciate ligament (ACL) reconstruction often present with enlarged or misplaced tunnels and bone grafting is required prior to the actual revision reconstruction. Autologous bone grafting features limited quantity and donor site morbidity. These problems may be eliminated utilizing cancellous bone allografts, but their efficiency and reliability have not been investigated systematically. The aim of the present study was to compare tunnel filling rates attained by utilizing either allogenic or autologous cancellous bone grafts.!##!Materials and methods!#!A total of 103 consecutive patients were enrolled retrospectively. All patients suffered from recurrent instability and underwent either allogenic or autologous cancellous bone grafting. Computed tomography (CT) was carried out before and after the bone grafting procedure. Based on preoperative CT scans, positioning and maximum diameter of the femoral and tibial tunnels were determined. Tunnel filling rates were calculated as a ratio of pre- and postoperative tunnel volumes. Primary outcome was the tibial tunnel filling rate. Femoral filling rates and density of the grafted bone were assessed secondarily.!##!Results!#!Preoperative CT scans revealed no significant differences between the two groups regarding distribution of misplacement and widening of the femoral or tibial tunnel. Postoperative CT scans were conducted after an interval of 5.2 months. Tunnel filling rates of 74.5% (± 14.3) femoral and 85.3% (± 10.3) tibial were achieved in the allogenic compared to 74.3% (± 15.9) femoral and 84.9% (± 9.4) tibial in the autologous group. With p values of 0.85 at the femur and 0.83 at the tibia, there were no significant differences between the groups. The density of the grafted bone revealed significantly higher values in the allogenic group.!##!Conclusions!#!Utilizing cancellous bone allografts in two-staged revision ACL surgery provides for sufficient and reproducible filling of enlarged or misplaced tunnels. The filling rates are comparable to those achieved with autologous bone grafting. Advantages of allografts are the unrestricted quantity and the absence of any harvesting procedure

    Patterns of Paternal Investment Predict Cross-Cultural Variation in Jealous Response

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    Long-lasting, romantic partnerships are a universal feature of human societies; but almost as ubiquitous is the risk of instability that comes when one partner strays. Jealous response to the threat of infidelity is a well-studied phenomenon, but most empirical work on the topic has focused on a proposed sex difference in the type of jealousy (sexual or emotional) men and women find most upsetting, rather than on how jealous response varies1,2. This stems in part from the predominance of studies using student samples from industrialized populations, which represent a relatively homogenous group in terms of age, life history stage, and social norms3,4. To better understand variation in partner jealousy, we conducted a two-part study in 11 populations (1,048 individuals), including eight small-scale societies, which examines how both sex and culture affect perceptions of infidelity. We show that, in spite of a robust sex difference, variation in jealous response is impacted more by the culture a respondent belongs to than by their sex. We further identify paternal investment and frequency of extramarital sex as two key predictors of cultural variation. Partner jealousy thus appears to be a facultative response, in part reflective of the variable risks and costs of men’s investment across societies

    Cyclin D1 and mammary carcinoma: new insights from transgenic mouse models

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    Cyclin D1 is one of the most commonly overexpressed oncogenes in breast cancer, with 45–50% of primary ductal carcinomas overexpressing this oncoprotein. Targeted deletion of the gene encoding cyclin D1 demonstrates an essential role in normal mammary gland development while transgenic studies provide evidence that cyclin D1 is a weak oncogene in mammary epithelium. In a recent exciting development, Yu et al. demonstrate that cyclin D1-deficient mice are resistant to mammary carcinomas induced by c-neu and v-Ha-ras, but not those induced by c-myc or Wnt-1. These findings define a pivotal role for cyclin D1 in a subset of mammary cancers in mice and imply a functional role for cyclin D1 overexpression in human breast cancer

    Review of the California Trawl Fishery for Pacific Ocean Shrimp, Pandalus jordani, from 1992 to 2007

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    The commercial bottom trawl fishery for Pacific ocean shrimp, Pandalus jordani, or pink shrimp, operates mostly off the west coast of the contiguous United States. The California portion of the fishery has not been thoroughly documented or reviewed since the 1991 fishing season, despite its fluctuating more during the last 16 years (1992–2007) than at any other period in its 56-year history. We used fishery-dependent data, California Department of Fish and Game commercial landing receipts and logbook data, to analyze trends and review the California pink shrimp trawl fishery from 1992 to 2007. In particular, we focus on the most recent years of the fishery (2001–07) to highlight the gear developments and key management measures implemented in the fishery. The fishery is primarily driven by market conditions and is highly regulated by both state and Federal management agencies. Several key regulatory measures implemented during this decade have had significant effects on the fishery. For example, the requirement of a Bycatch Reduction Device on trawl nets targeting pink shrimp was approved in 2001 and has greatly reduced levels of finfish bycatch. Fishery production has declined, particularly in recent years, and may be attributed to decreased market prices, followed by reduced fishermen participation; both of which are related to changes in the processing sector and demand for the product
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