1,540 research outputs found

    Extending the Ehresmann-Schein-Nambooripad Theorem

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    We extend the `join-premorphisms' part of the Ehresmann-Schein-Nambooripad Theorem to the case of two-sided restriction semigroups and inductive categories, following on from a result of Lawson (1991) for the `morphisms' part. However, it is so-called `meet-premorphisms' which have proved useful in recent years in the study of partial actions. We therefore obtain an Ehresmann-Schein-Nambooripad-type theorem for meet-premorphisms in the case of two-sided restriction semigroups and inductive categories. As a corollary, we obtain such a theorem in the inverse case.Comment: 23 pages; final section on Szendrei expansions removed; further reordering of materia

    A computer system to analyze showers in nuclear emulsions: Center Director's discretionary fund report

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    A system to rapidly digitize data from showers in nuclear emulsions is described. A TV camera views the emulsions though a microscope. The TV output is superimposed on the monitor of a minicomputer. The operator uses the computer's graphics capability to mark the positions of particle tracks. The coordinates of each track are stored on a disk. The computer then predicts the coordinates of each track through successive layers of emulsion. The operator, guided by the predictions, thus tracks and stores the development of the shower. The system provides a significant improvement over purely manual methods of recording shower development in nuclear emulsion stacks

    The influence of risk factors associated with captive rearing on post-release survival in translocated cirl buntings Emberiza cirlus in the UK

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    Population decline resulting from agricultural intensification led to contraction of the range of the cirl bunting Emberiza cirlus in the UK to a small area of south Devon. As part of the UK Biodiversity Action Plan for the species, a project to re-establish a population in suitable habitat in Cornwall was undertaken during 2006–2011, in which chicks were removed from the nest in Devon, hand-reared and then delayed-released. The survival of the birds to four time points in the year after release was analysed in relation to the effect of rearing factors, using a multivariable logistic regression model. Individuals with higher body weight at capture were more likely to survive to 1 January and 1 May in the year following release, and individuals released in June and July were more likely to survive than those released in August. Individuals released in 2006 and 2011 had a higher survival rate than those released during 2007–2010. Timing of capture, time spent at each stage in captivity, medication and the detection of parasites in the brood had no significant effect. Immunosuppressive disease, weather factors and predator activity may have led to some of the observed differences in survival. This analysis provides evidence with which to plan future translocation projects for cirl buntings and other passerine birds

    Innate immune pathways associated with lung radioprotection by soy isoflavones

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    Introduction: Radiation therapy for lung cancer causes pneumonitis and fibrosis. Soy isoflavones protect against radiation-induced lung injury, but the mediators of radio- protection remain unclear. We investigated the effect of radiation on myeloid-derived suppressor cells (MDSCs) in the lung and their modulation by soy isoflavones for a potential role in protection from radiation-induced lung injury. Methods: BALB/c mice (5–6 weeks old) received a single 10 Gy dose of thoracic irra- diation and soy isoflavones were orally administrated daily before and after radiation at 1 mg/day. Arginase-1 (Arg-1) and nuclear factor κB (NF-κB) p65 were detected in lung tissue by western blot analysis and immunohistochemistry. Lung MDSC subsets and their Arg-1 expression were analyzed by flow cytometry. Cytokine levels in the lungs were measured by ELISA. Results: At 1 week after radiation, CD11b+ cells expressing Arg-1 were decreased by radiation in lung tissue yet maintained in the lungs treated with radiation and soy isoflavones. Arg-1 was predominantly expressed by CD11b+Ly6ClowLy6G+ granulocytic MDSCs (gr-MDSCs). Arg-1 expression in gr-MDSCs was reduced by radiation and preserved by supplementation with soy isoflavones. A persistent increase in Arg-1+ cells was observed in lung tissue treated with combined radiation and soy isoflavones at early and late time points, compared to radiation alone. The increase in Arg-1 expression mediated by soy isoflavones could be associated with the inhibition of radiation-induced activation of NF-κB and the control of pro-inflammatory cytokine production demon- strated in this study. Conclusion: A radioprotective mechanism of soy isoflavones may involve the promotion of Arg-1-expressing gr-MDSCs that could play a role in downregulation of inflammation and lung radioprotection

    Measurements and calculations of the Coulomb cross section for the production of direct electron pairs by energetic heavy nuclei in nuclear track emulsion

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    Measurements and theoretical predictions of the Coulomb cross section for the production of direct electron pairs by heavy ions in emulsion have been performed. Nuclear track emulsions were exposed to the 1.8 GeV/amu Fe-56 beam at the Lawrence Berkeley Laboratory bevalac and to the 60 and 200 GeV/amu O-16 and the 200 GeV/amu S-32 beam at the European Center for Nuclear Research Super Proton Synchrotron modified to accelerate heavy ions. The calculations combine the Weizsacker-Williams virtual quanta method applicable to the low-energy transfers and the Kelner-Kotov relativistic treatment for the high-energy transfers. Comparison of the measured total electron pair yield, the energy transfer distribution, and the emission angle distribution with theoretical predictions revealed a discrepancy in the frequency of occurrence of the low-energy pairs (less than or = 10 MeV). The microscope scanning criteria used to identify the direct electron pairs is described and efforts to improve the calculation of the cross section for pair production are also discussed

    Composition and energy spectra of cosmic ray nuclei above 500 GeV/nucleon from the JACEE emulsion chambers

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    The composition and energy spectra of charge groups (C - 0), (Ne - S), and (Z approximately 17) above 500 GeV/nucleon from the experiments of JACEE series balloonborne emulsion chambers are reported. Studies of cosmic ray elemental composition at higher energies provide information on propagation through interstellar space, acceleration mechanisms, and their sources. One of the present interests is the elemental composition at energies above 100 GeV/nucleon. Statistically sufficient data in this energy region can be decisive in judgment of propagation models from the ratios of SECONDARY/PRIMARY and source spectra (acceleration mechanism), as well as speculative contributions of different sources from the ratios of PRIMARY/PRIMARY. At much higher energies, i.e., around 10 to the 15th power eV, data from direct observation will give hints on the knee problem, as to whether they favor an escape effect possibly governed by magnetic rigidity above 10 to the 16th power eV

    Characteristics of central collision events in Fe-nucleus interactions for 20 - 60 GeV/nucleon

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    A counter emulsion hybrid chamber in Japanese-American Cooperative Emulsion Experiment (JACEE-3) was flown on a balloon at the altitude (5.4 g/sq cm) in 1982 with the objective of probing the heavy nuclear collisions above 20 GeV per nucleon. In the energy region, it is suggested that nucleus-nucleus collisions provide dense collisions complex through compression and secondary particle production. In the lower energy region, an evidence of collective flow has been reported. And also, at higher energy region, it has been argued that nucleus has rather large stopping power. In this paper, the high multiplicity characteristics of Fe nucleus central collisions with energies 20 to 50 GeV/nucleon are presented. This is considered to be relevant to compressibility and collective flow of nuclear matter

    New calculations and measurements of the Coulomb cross-section for the production of direct electron pairs by high energy nuclei

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    Recently, new calculations were made of the direct Coulomb pair cross section that rely less in arbitrary parameters. More accurate calculations of the cross section down to low pair energies were made. New measurements of the total direct electron pair yield, and the energy and angular distribution of the electron pairs in emulsion were made for O-16 at 60 and 200 GeV/amu at S-32 at 200 GeV/amu which give satisfactory agreement with the new calculations. These calculations and measurements are presented along with previous accelerator measurements made of this effect during the last 40 years. The microscope scanning criteria used to identify the direct electron pairs is described. Prospects for application of the pair method to cosmic ray energy measurements in the region 10 (exp 13) to 10 (exp 15) eV/amu are discussed

    Primary cosmic ray spectra in the range 20-60 GeV/n

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    Energy spectra for primary cosmic rays C-Fe above 20 GeV/n were measured on a balloon flight from Greenville S.C. in June 1982 with a hybrid electronic counter-emulsion chamber experiment. Fluxes above the atmosphere appear in general agreement with previously published values. The heavy events included in this data will be used along with the JACEE passive chamber data to provide a heavy composition direct measurement from 10 to the 12th power to approximately 10 to the 15th power eV total energy
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