5,179 research outputs found

    Algebras for parameterised monads

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    Parameterised monads have the same relationship to adjunctions with parameters as monads do to adjunctions. In this paper, we investigate algebras for parameterised monads. We identify the Eilenberg-Moore category of algebras for parameterised monads and prove a generalisation of Beck’s theorem characterising this category. We demonstrate an application of this theory to the semantics of type and effect systems

    Challenges Of The UNCG/Tec De Monterrey/Disney College Program

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    This report is based on a study of participants in an international, academic exchange program that includes a Walt Disney World internship. The University of North Carolina at Greensboro (UNCG) was a principal partner in developing the UNCG/Tec de Monterrey/Disney College Program (UNCG Program). This cooperative arrangement involves students enrolled in degree programs at one of the Tec de Monterrey campuses in Mexico. The report analyzes the challenges faced by the UNCG Program Director and assisting faculty in the early development of the UNCG Program as well as the challenges presented since the Program has matured

    Survival and selection biases in early animal evolution and a source of systematic overestimation in molecular clocks

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    Important evolutionary events such as the Cambrian Explosion have inspired many attempts at explanation: why do they happen when they do? What shapes them, and why do they eventually come to an end? However, much less attention has been paid to the idea of a ‘null hypothesis’—that certain features of such diversifications arise simply through their statistical structure. Such statistical features also appear to influence our perception of the timing of these events. Here, we show in particular that study of unusually large clades leads to systematic overestimates of clade ages from some types of molecular clocks, and that the size of this effect may be enough to account for the puzzling mismatches seen between these molecular clocks and the fossil record. Our analysis of the fossil record of the late Ediacaran to Cambrian suggests that it is likely to be recording a true evolutionary radiation of the bilaterians at this time, and that explanations involving various sorts of cryptic origins for the bilaterians do not seem to be necessary

    Hilbert-Post completeness for the state and the exception effects

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    In this paper, we present a novel framework for studying the syntactic completeness of computational effects and we apply it to the exception effect. When applied to the states effect, our framework can be seen as a generalization of Pretnar's work on this subject. We first introduce a relative notion of Hilbert-Post completeness, well-suited to the composition of effects. Then we prove that the exception effect is relatively Hilbert-Post complete, as well as the "core" language which may be used for implementing it; these proofs have been formalized and checked with the proof assistant Coq.Comment: Siegfried Rump (Hamburg University of Technology), Chee Yap (Courant Institute, NYU). Sixth International Conference on Mathematical Aspects of Computer and Information Sciences , Nov 2015, Berlin, Germany. 2015, LNC

    Cosmic ray LET spectra and doses on board Cosmos-2044 biosatellite

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    Results of the experiments on board Cosmos-2044 (Biosatellite 9) are presented. Various nuclear track detectors (NTD) (dielectric, AgCl-based, nuclear emulsions) were used to obtain the Linear Energy Transfer (LET) spectra inside and outside the satellite. The spectra from the different NTDs have proved to be in general agreement. The results of LET spectra calculations using two different models are also presented. The resultant LET distributions are used to calculate the absorbed and equivalent doses and the orbit-averaged quality factors (QF) of the cosmic rays (CR). Absorbed dose rates inside (approximately 20 g cm (exp -2) shielding) and outside (1 g cm(exp -2) the spacecraft, omitting electrons, were found to be 4.8 and 8.6 mrad d (exp -1), respectively, while the corresponding equivalent doses were 8.8 and 19.7 mrem d(exp -1). The effects of the flight parameters on the total fluence of, and on the dose from the CR particles are analyzed. Integral dose distributions of the detected particles are also determined. The LET values which separate absorbed and equivalent doses into 50% intervals are estimated. The CR-39 dielectric NTD is shown to detect 20-30% of the absorbed dose and 60-70% of the equivalent dose in the Cosmos-2044 orbit. The influence of solar activity phase on the magnitude of CR flux is discussed

    Renal allograft recipients with high susceptibility to cutaneous malignancy have an increased prevalence of human papillomavirus DNA in skin tumours and a greater risk of anogenital malignancy.

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    Renal allograft recipients (RARs) have a well-documented increased incidence of viral warts and cutaneous neoplasia, particularly those with long graft life and high sun exposure. A clinicopathological survey of 69 RARs in south-east Scotland, with follow-up periods of up to 28 years after transplantation, revealed marked variation in patient susceptibility to cutaneous malignancy with concomitant variation in HPV prevalence. Skin cancers were found in 34 patients. Eight patients showed high susceptibility [defined as more than four intraepidermal carcinomas (IECs) or invasive squamous cell carcinomas (SCCs)] 42 had intermediate susceptibility (1-3 IECs or SCCs, or >3 keratoses) and 18 had low susceptibility (< or = 3 keratoses and no cancers). SCCs, IECs and keratoses from the high-susceptibility group were found to have greater prevalences of human papillomavirus (HPV) DNA (56%, 45% and 50% respectively), than SCCs (0%) and IECs (33%) from intermediate-susceptibility RARs and keratoses (36%) from the combined intermediate- and low-susceptibility groups and compared with a group of immunocompetent controls (27%, 20% and 15% respectively). No differences in p53 protein accumulation, determined immunohistochemically, were observed in tumours from the three groups. Categorization of RARs by susceptibility to cutaneous malignancy provides clinically useful information, as significantly more high-susceptibility patients (38%) developed aggressive, potentially lethal anogenital or cutaneous squamous cell cancers than did patients in the intermediate group (5%, P=0.005) or the low-susceptibility group (0%)

    Accumulation of p53 is associated with tumour progression in cutaneous lesions of renal allograft recipients.

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    Renal allograft recipients suffer from a markedly increased susceptibility to premalignant and malignant cutaneous lesions. Although various aetiological factors have been implicated, little is known of the associated genetic events. In this study we initially employed immunocytochemical techniques to investigate the prevalence and localisation of accumulated p53 in over 200 cutaneous biopsies (including 56 squamous cell carcinomas) from renal allograft recipients and immunocompetent controls. In renal allograft recipients accumulated p53 was present in 24% of uninvolved skin samples, 14% of viral warts, 41% of premalignant keratoses, 65% of intraepidermal carcinomas and 56% of squamous cell carcinomas [squamous cell carcinoma and intraepidermal carcinoma differed significantly from uninvolved skin (P < 0.005) and viral warts (P < 0.01)]. A similar trend was revealed in immunocompetent patients (an older, chronically sun-exposed population) but with lower prevalence of p53 immunoreactivity: 25% of uninvolved skin samples, 0% of viral warts, 25% of keratoses, 53% of intraepidermal carcinomas and 53% of squamous cell carcinomas. These differences were not statistically significant. Morphologically, p53 immunoreactivity strongly associated with areas of epidermal dysplasia and the abundance of staining correlated positively with the severity of dysplasia. These data suggest that p53 plays a role in skin carcinogenesis and is associated with progression towards the invasive state. No correlation was observed between accumulated p53 and the presence of human papillomavirus (HPV) DNA in any of the lesions. Single-strand conformational polymorphism analysis (exons 5-8) was used to determine the frequency of mutated p53 in 28 malignancies with varying degrees of immunopositivity. p53 mutations were found in 5/9 (56%) malignancies with p53 staining in > 50% of cells, reducing to 1/6 (17%) where 10-50% of cells were positively stained and none where < 10% of cells were stained. These data imply that factors other than p53 gene mutation play a part in accumulation of p53 in skin cancers

    Using a Modified \u3ci\u3eIn-Vitro\u3c/i\u3e Procedure to Measure Corn Bran Buoyancy

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    An in vitro procedure was modified to estimate rumen buoyancy of corn bran and fiber types. Inoculum was obtained from two beef heifers and mixed with McDougall’s buffer then distributed to the in vitro tubes for 30 hours incubation at 100 °F. Fibrous material formed a matte layer which was measured to describe buoyancy. Tubes contained 6g of a feedlot-type diet with 7.5% fiber type (alfalfa hay, grass hay, corn silage, or corn stalks), with no replacement or 25% replacement of the remaining corn with corn bran. Buoyancy declined over time. Alfalfa hay had the most positive effect on buoyancy of corn bran. This new method offers promise for describing rumen buoyancy

    Isotopic evidence for the diversity of late Quaternary loess in Nebraska: Glaciogenic and nonglaciogenic sources

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    Pb isotope compositions of detrital K-feldspars and U-Pb ages of detrital zircons are used as indicators for determining the sources of Peoria Loess deposited during the last glacial period (late Wisconsin, ca. 25–14 ka) in Nebraska and western Iowa. Our new data indicate that only loess adjacent to the Platte River has Pb isotopic characteristics suggesting derivation from this river. Most Peoria Loess in central Nebraska (up to 20 m thick) is non-glaciogenic, on the basis of Pb isotope ratios in K-feldspars and the presence of 34-Ma detrital zircons. These isotopic characteristics suggest derivation primarily from the Oligocene White River Group in southern South Dakota, western Nebraska, southeastern Wyoming, and northeastern Colorado. The occurrence of 10–25 Ma detrital zircons suggests additional minor contributions of silt from the Oligocene-Miocene Arikaree Group and Miocene Ogallala Group

    Isotopic evidence for the diversity of late Quaternary loess in Nebraska: Glaciogenic and nonglaciogenic sources

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    Pb isotope compositions of detrital K-feldspars and U-Pb ages of detrital zircons are used as indicators for determining the sources of Peoria Loess deposited during the last glacial period (late Wisconsin, ca. 25–14 ka) in Nebraska and western Iowa. Our new data indicate that only loess adjacent to the Platte River has Pb isotopic characteristics suggesting derivation from this river. Most Peoria Loess in central Nebraska (up to 20 m thick) is non-glaciogenic, on the basis of Pb isotope ratios in K-feldspars and the presence of 34-Ma detrital zircons. These isotopic characteristics suggest derivation primarily from the Oligocene White River Group in southern South Dakota, western Nebraska, southeastern Wyoming, and northeastern Colorado. The occurrence of 10–25 Ma detrital zircons suggests additional minor contributions of silt from the Oligocene-Miocene Arikaree Group and Miocene Ogallala Group
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