753 research outputs found

    Taxonomy of North American fish Eimeriidae

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    Taxonomic descriptions, line drawings, and references are given for the 30 named and 5 unnamed species of North American fish Eimeriidae. In addition, a key was developed based on available morphologic data to distinguish between similar species. Taxa are divided into two genera: Eimeria (27 species) which are tetr&sporocystic with dizoic, nonbivalved sporocysts, and Goussia (3 species) which are tetrasporocystic with dizoic, bivalved sporocysts that lack Stleda bodies and have sporocyst walls composed of two longitudinal valves. (PDF file contains 24 pages.

    \u3ci\u3eMyxosoma funduli\u3c/i\u3e Kudo 1918 (Protozoa: Myxosporida) in \u3ci\u3eFundulus kansae\u3c/i\u3e: Summer Epizootiology

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    The occurrence and distribution of the myxosporidan Myxosoma funduli on the gills of the plains killifish (Fundulus kansae) were investigated; Fundulus kansae is reported as a new host. Host samples from various sites on the South Platte River, Nebraska, were collected during the summer months of 1975 and 1976. The protozoan parasite population was shown to be overdispersed within the host population, and this distribution was similar to that described by the negative binomial equation. Demographic characteristics of the infected fish subpopulation were virtually identical to those of the whole fish population. Infection intensity was independent of gill bar number or side. The frequency of bilateral infections was 0.54, of left only infections was 0.23, and of right only infections was 0.22. Distribution of immature and mature plasmodia indicated that a pre-existing infection did not preclude a new infection, and suggested a prepatent period of less than two months

    The complete spectrum of the area from recoupling theory in loop quantum gravity

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    We compute the complete spectrum of the area operator in the loop representation of quantum gravity, using recoupling theory. This result extends previous derivations, which did not include the ``degenerate'' sector, and agrees with the recently computed spectrum of the connection-representation area operator.Comment: typos corrected in eqn.(21). Latex with IOP and epsf styles, 1 figure (eps postscript file), 12 pages. To appear in Class. Quantum Gra

    Charm mass dependence of the weak Hamiltonian in chiral perturbation theory

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    Suppose that the weak interaction Hamiltonian of four-flavour SU(4) chiral effective theory is known, for a small charm quark mass m_c. We study how the weak Hamiltonian changes as the charm quark mass increases, by integrating it out within chiral perturbation theory to obtain a three-flavour SU(3) chiral theory. We find that the ratio of the SU(3) low-energy constants which mediate Delta I=1/2 and Delta I=3/2 transitions, increases rather rapidly with m_c, as \sim m_c ln (1/m_c). The logarithmic effect originates from "penguin-type" charm loops, and could represent one of the reasons for the Delta I=1/2 rule.Comment: 20 pages. v2: references and clarifications added, published versio

    Cryptosporidium, Enterocytozoon, and Cyclospora Infections in Pediatric and Adult Patients with Diarrhea in Tanzania.

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    Cryptosporidiosis, microsporidiosis, and cyclosporiasis were studied in four groups of Tanzanian inpatients: adults with AIDS-associated diarrhea, children with chronic diarrhea (of whom 23 of 59 were positive [+] for human immunodeficiency virus [HIV]), children with acute diarrhea (of whom 15 of 55 were HIV+), and HIV control children without diarrhea. Cryptosporidium was identified in specimens from 6/86 adults, 5/59 children with chronic diarrhea (3/5, HIV+), 7/55 children with acute diarrhea (0/7, HIV+), and 0/20 control children. Among children with acute diarrhea, 7/7 with cryptosporidiosis were malnourished, compared with 10/48 without cryptosporidiosis (P < .01). Enterocytozoon was identified in specimens from 3/86 adults, 2/59 children with chronic diarrhea (1 HIV+), 0/55 children with acute diarrhea, and 4/20 control children. All four controls were underweight (P < .01). Cyclospora was identified in specimens from one adult and one child with acute diarrhea (HIV-). Thus, Cryptosporidium was the most frequent and Cyclospora the least frequent pathogen identified. Cryptosporidium and Enterocytozoon were associated with malnutrition. Asymptomatic fecal shedding of Enterocytozoon in otherwise healthy, HIV children has not been described previously

    Flavor Changing Neutral Currents involving Heavy Quarks with Four Generations

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    We study various FCNC involving heavy quarks in the Standard Model (SM) with a sequential fourth generation. After imposing BXsγB\to X_s\gamma, BXsl+lB\to X_sl^+l^- and ZbbˉZ\to b\bar{b} constraints, we find B(Zsbˉ+sˉb){\cal B}(Z\to s\bar{b}+\bar{s}b) can be enhanced by an order of magnitude to 10710^{-7}, while tcZ,cHt\to cZ, cH decays can reach 10610^{-6}, which are orders of magnitude higher than in SM. However,these rates are still not observable for the near future.With the era of LHC approaching, we focus on FCNC decays involving fourth generation bb^\prime and tt^\prime quarks. We calculate the rates for loop induced FCNC decays bbZ,bH,bg,bγb^\prime\to bZ, bH, bg, b\gamma, as well as t^\prime\to tZ,\tH, tg, t\gamma. If Vcb|V_{cb'}| is of order Vcb0.04|V_{cb}| \simeq 0.04, tree level bcWb^\prime\to cW decay would dominate, posing a challenge since bb-tagging is less effective. For VcbVcb|V_{cb'}| \ll |V_{cb}|, btWb'\to tW would tend to dominate, while btWb'\to t^\prime W^* could also open for heavier bb', leading to thepossibility of quadruple-WW signals via bbˉbbˉW+WW+Wb'\bar b'\to b\bar b W^+W^-W^+W^-. The FCNC bbZ,bHb'\to bZ, bH decays could still dominate if mbm_{b'} is just above 200 GeV. For the case of tt', ingeneral tbWt^\prime\to bW would be dominant, hence it behaves like a heavy top. For both bb' and tt', except for the intriguing light bb' case, FCNC decays are in the 10410210^{-4} -10^{-2} range, and are quite detectable at the LHC.For a possible future ILC, we find the associated production of FCNC e+ebsˉe^+e^-\to b\bar s, tcˉt\bar c are below sensitivity, while e+ebbˉe^+e^-\to b^\prime\bar b andttˉt^\prime\bar t can be better probed.Tevatron Run-II can still probe the lighter bb' or tt' scenario. LHC would either discover the fourth generation and measure the FCNC rates, or rule out the fourth generation conclusively.Comment: 31 pages, 15 eps figures, version to appear in JHE

    Efficiency of split-mouth designs

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    . The purpose of this paper is (1) to investigate the similarity of the amount, distribution, and, severity of periodontal disease of the within-patient experimental units, (2) to estimate the relative efficiencies of split-mouth designs when compared to whole-mouth designs, and (3) to discuss how stratification on initial pocket depth can result in large differences in the power of the test-statistics in the different disease categories. Periodontal disease characteristics are not always homogeneously distributed over the within-patient experimental units and this heterogeneity can reduce the efficiency of split-mouth designs. In particular, if analyses are stratified on initial pocket depth, sites with an initial probing depth deeper than 6 mm may be small in number and asymmetrically distributed when compared to sites with an initial probing depth less than 6 mm. This may result in large differences of the power of the test statistics among the different disease categories and should lead to a careful interpretation of the statistical significance tests. When disease characteristics are symmetrically distributed over the within-patient experimental units and a sufficient number of sites is present per experimental unit, the split-mouth design can provide moderate to large gains in relative efficiency. In the absence of a symmetric disease distribution, wholemouth clinical trials may be preferable.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/75701/1/j.1600-051X.1990.tb01060.x.pd

    Seesaw mechanism in the sneutrino sector and its consequences

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    The seesaw-extended MSSM provides a framework in which the observed light neutrino masses and mixing angles can be generated in the context of a natural theory for the TeV-scale. Sneutrino-mixing phenomena provide valuable tools for connecting the physics of neutrinos and supersymmetry. We examine the theoretical structure of the seesaw-extended MSSM, retaining the full complexity of three generations of neutrinos and sneutrinos. In this general framework, new flavor-changing and CP-violating sneutrino processes are allowed, and are parameterized in terms of two 3×33\times 3 matrices that respectively preserve and violate lepton number. The elements of these matrices can be bounded by analyzing the rate for rare flavor-changing decays of charged leptons and the one-loop contribution to neutrino masses. In the former case, new contributions arise in the seesaw extended model which are not present in the ordinary MSSM. In the latter case, sneutrino--antisneutrino mixing generates the leading correction at one-loop to neutrino masses, and could provide the origin of the observed texture of the light neutrino mass matrix. Finally, we derive general formulae for sneutrino--antisneutrino oscillations and sneutrino flavor-oscillations. Unfortunately, neither oscillation phenomena is likely to be observable at future colliders.Comment: 69 pages, 5 figures, uses axodraw.sty. Version accepted for publication in JHEP: some comments and one more Appendix with additional discussion added, references update

    Opera and poison : a secret and enjoyable approach to teaching and learning chemistry

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    The storyline of operas, with historical or fictional characters, often include potions and poisons. This has prompted a study of the chemistry behind some operatic plots. The results were originally presented as a lecture given at the University of Minho in Portugal, within the context of the International Year of Chemistry. The same lecture was subsequently repeated at other universities as an invited lecture for science students and in public theaters for wider audiences. The lecture included a multimedia and interactive content that allowed the audience to listen to arias and to watch video clips with selected scenes extracted from operas. The present article, based on the lecture, demonstrates how chemistry and opera can be related and may also serve as a source of motivation and inspiration for chemistry teachers looking for alternative pedagogical approaches. Moreover, the lecture constitutes a vehicle that transports chemistry knowledge to wider audiences through examples of everyday molecules, with particular emphasis on natural products.The author is pleased to express his gratitude to Jorge Calado and Michael John Smith for useful discussions. The author also thanks the reviewers of the manuscript for their helpful comments and suggestions. Thanks are due to the Foundation for Science and Technology (FCT,Portugal), QREN and FEDER/EU for financial support through the research centers, CQ/UM PEst-C/QUI/UI0686/2011. Ciencia Viva, Portugal, is also acknowledged for financial support of the activities organized by the University of Minho during the International Year of Chemistry. The author also expresses his gratitude to Ana Paula Ferreira and Andre Cunha Leal from RTP Antena 2 who contributed immensely to the popularization of the lecture on which this paper is based on

    Investigating falls in adults with intellectual disability living in community settings and their experiences of post-fall care services: Protocol for a prospective observational cohort study

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    Background: Falls among older adults with intellectual disability (ID) are recognised as a serious health problem potentially resulting in reduced health-related quality of life and premature placement in residential care. However there are limited studies that have investigated this problem and thus falls rates among older adults with ID remain uncertain. Furthermore, people with ID rely heavily on familial and professional care support to address health problems, such as after having a fall. No studies have explored the post-fall care that people with ID receive. Method: This research will be carried out in two phases using a convergent mixed methods design. The aim of Phase 1 is to estimate the falls rate by prospectively observing a cohort of older adults (≥ 35 years) with ID (n = 90) for six months. Phase 1 will be conducted according to STROBE guidelines. In Phase 2, participants from Phase 1 who have experienced a fall(s) will be asked to participate in a semi-structured interview to explore their post-fall experience. Discussion: This study will determine the rate of falls among older adults with ID living in community based settings, which will assist to identify the extent of this problem. Data collected from the study will also aid in understanding the circumstance of falls and related falls risk factors in this cohort. This will include exploring any barriers that older adults with ID may encounter when seeking or undertaking recommended post-fall care advice. Findings from this research will potentially inform future development of falls prevention services for older adults with ID. This study has been approved by the University Human Research Ethics Committee. Trial registration: The protocol for this study is registered with the Australian New Zealand Clinical Trial Registry (ACTRN12615000926538) on 7 September 2015. www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=368990&isReview=tru
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