2,603 research outputs found

    Daily Life at the Pontifical North American College

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    Relaxed Bell inequalities and Kochen-Specker theorems

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    The combination of various physically plausible properties, such as no signaling, determinism, and experimental free will, is known to be incompatible with quantum correlations. Hence, these properties must be individually or jointly relaxed in any model of such correlations. The necessary degrees of relaxation are quantified here, via natural distance and information-theoretic measures. This allows quantitative comparisons between different models in terms of the resources, such as the number of bits, of randomness, communication, and/or correlation, that they require. For example, measurement dependence is a relatively strong resource for modeling singlet state correlations, with only 1/15 of one bit of correlation required between measurement settings and the underlying variable. It is shown how various 'relaxed' Bell inequalities may be obtained, which precisely specify the complementary degrees of relaxation required to model any given violation of a standard Bell inequality. The robustness of a class of Kochen-Specker theorems, to relaxation of measurement independence, is also investigated. It is shown that a theorem of Mermin remains valid unless measurement independence is relaxed by 1/3. The Conway-Kochen 'free will' theorem and a result of Hardy are less robust, failing if measurement independence is relaxed by only 6.5% and 4.5%, respectively. An appendix shows the existence of an outcome independent model is equivalent to the existence of a deterministic model.Comment: 19 pages (including 3 appendices); v3: minor clarifications, to appear in PR

    Electrical coupling between ventricular myocytes and myofibroblasts in the infarcted mouse heart

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    Aims: Recent studies have demonstrated electrotonic coupling between scar tissue and the surrounding myocardium in cryoinjured hearts. However, the electrical dynamics occurring at the myocyte-nonmyocyte interface in the fibrotic heart remain undefined. Here, we sought to develop an assay to interrogate the nonmyocyte cell type contributing to heterocellular coupling and to characterize, on a cellular scale, its voltage response in the infarct border zone of living hearts. Methods and results: We used two-photon laser scanning microscopy in conjunction with a voltage-sensitive dye to record transmembrane voltage changes simultaneously from cardiomyocytes and adjoined nonmyocytes in Langendorff-perfused mouse hearts with healing myocardial infarction. Transgenic mice with cardiomyocyte-restricted expression of a green fluorescent reporter protein underwent permanent coronary artery ligation and their hearts were subjected to voltage imaging 7-10 days later. Reporter-negative cells, i.e. nonmyocytes, in the infarct border zone exhibited depolarizing transients at a 1:1 coupling ratio with action potentials recorded simultaneously from adjacent, reporter-positive ventricular myocytes. The electrotonic responses in the nonmyocytes exhibited slower rates of de- and repolarization compared to the action potential waveform of juxtaposed myocytes. Voltage imaging in infarcted hearts expressing a fluorescent reporter specifically in myofibroblasts revealed that the latter were electrically coupled to border zone myocytes. Their voltage transient properties were indistinguishable from those of nonmyocytes in hearts with cardiomyocyte-restricted reporter expression. The density of connexin43 expression at myofibroblast-cardiomyocyte junctions was ∼5% of that in the intercalated disc regions of paired ventricular myocytes in the remote, uninjured myocardium, whereas the ratio of connexin45 to connexin43 expression levels at heterocellular contacts was ∼1%. Conclusion: Myofibroblasts contribute to the population of electrically coupled nonmyocytes in the infarct border zone. The slower kinetics of myofibroblast voltage responses may reflect low electrical conductivity across heterocellular junctions, in accordance with the paucity of connexin expression at myofibroblast-cardiomyocyte contacts

    Interactions of Cbl with Grb2 and phosphatidylinositol 3\u27-kinase in activated Jurkat cells

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    T-cell receptor (TCR) cross-linking increases tyrosine phosphorylation of multiple proteins, only a few of which have been identified. One of the most rapidly tyrosine-phosphorylated polypeptides is the 120-kDa product of the proto-oncogene c-cbl, a cytosolic and cytoskeletal protein containing multiple proline-rich motifs that are potential binding sites for proteins containing Src homology 3 (SH3) domains. We report here that in cultured Jurkat T cells, Cbl is coprecipitated with antibody against the adapter protein Grb2. Upon activation of Jurkat T cells via the TCR-CD3 complex, we find that high-affinity binding of Cbl requires the N-terminal SH3 domain of GST-Grb2 fusion protein but after cross-linking of the TCR-CD3 and CD4 receptors, Cbl binds equally to its SH2 domain. Grb2 antisera also precipitated p85 from serum-starved cells, while TCR activation increased p85 and tyrosine-phosphorylated Cbl but not Cbl protein in Grb2 immunocomplexes. Phosphatidylinositol (PI) 3-kinase activity was immunoprecipitated from serum-starved cells with Cbl and to a lesser extent with Grb2 antisera, and TCR cross-linking increased this activity severalfold. The PI 3-kinase activity associated with Cbl amounted to 5 to 10% of the total cellular activity that could be precipitated by p85 antisera. The Ras exchange factor Son-of-sevenless 1 (Sos-1) was not found in anti-Cbl immunoprecipitates from activated cells, and Cbl was not detectable in anti-Sos-1 precipitates, supporting the likelihood that Sos-Grb2 and Cbl-Grb2 are present as distinct complexes. Taken together, these data suggest that Cbl function in Jurkat T cells involves its constitutive association with Grb2 and its recruitment of PI 3-kinase in response to TCR activation

    The Effects of Poetry in Elderly Populations with Memory Impairment

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    Introduction. A small body of research on therapeutic use of poetry in individuals with memory impairment demonstrates benefits similar to that of more widely studied music interventions. This project aims to assess the effects of participation in a poetry group on the residents of a memory care floor within the Converse Home, an assisted living facility in Burlington, Vermont. Methods.. We evaluated the effects of twelve group poetry sessions on residents\u27 well-being in several domains. Each session included a reading and writing portion, which were evaluated separately to assess differences in measures of communication, interest, and enjoyment. These measures, along with negative responses, were recorded on Likert scales. T-tests, ANOVA, and post-hoc comparisons were used to compare behavioral and affective observations in the reading versus writing sessions. Results.. Positive responses were significantly higher in reading sessions (p Conclusion.. Although the limitations of this project preclude us from drawing individual conclusions regarding the therapeutic efficacy of poetry in individuals with memory impairment, we demonstrate that poetry sessions have a positive impact on global quality of life outcomes and introduction of poetry sessions in this population has a beneficial effect.https://scholarworks.uvm.edu/comphp_gallery/1242/thumbnail.jp

    Initial investigation of seasonal flammability of three invasive East Texas forest understory fuels using thermogravimetric analysis

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    East Texas forest understory fuels have become increasingly infested with invasive species which have contributed to greater hazardous fuel loads when combined with decades of fire exclusion and passive management. This study focused on estimating seasonal changes in flammability parameters of invasive yaupon (Ilex vomitoria), Chinese privet (Ligustrum sinense), and Chinese tallow (Triadica sebifera) using thermogravimetric analysis. Foliage and stem samples were collected in the dormant (February) and growing (August) seasons. Differential thermogravimetric (DTG) and proximate analyses were used to estimate species specific flammability parameters related to relative spontaneous ignition temperature (RSIT), gas-phase maximum mass loss rate (GP-MMLR), and combustion duration (GP-CD). Seasonality played a significant role among species RSIT (p\u3c0.0001) and GP-CD (p\u3c0.03). Proximate analysis VM% was relatively consistent with flammability indices, while the combination of VM% and ash% helped explain some inconsistencies. Yaupon exhibited the greatest foliage ignitability (\u3eRSIT) and combustibility (\u3eGP-MMLR) followed by Chinese privet and tallow. Consequently, yaupon poses a significant year round wildfire and fire management risk. Chinese privets’ greater dormant season ignitability may improve prescribed fire control efforts in mid-winter, but may also pose a significant wildfire risk during drought and windy conditions. Chinese tallow stems’ greater growing season flammability may enhance integrated control measures using prescribed fire in late summer and early fall. In summary, these data further local knowledge related to seasonal and relative plant flammability and may be useful as additional inputs into custom fuel models, as well as assigning flammability hazard ratings for ornamental vegetation within the wildland-urban interface

    Supersymmetric quantum cosmological billiards

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    D=11 Supergravity near a space-like singularity admits a cosmological billiard description based on the hyperbolic Kac-Moody group E10. The quantization of this system via the supersymmetry constraint is shown to lead to wavefunctions involving automorphic (Maass wave) forms under the modular group W^+(E10)=PSL(2,O) with Dirichlet boundary conditions on the billiard domain. A general inequality for the Laplace eigenvalues of these automorphic forms implies that the wave function of the universe is generically complex and always tends to zero when approaching the initial singularity. We discuss possible implications of this result for the question of singularity resolution in quantum cosmology and comment on the differences with other approaches.Comment: 4 pages. v2: Added ref. Version to be published in PR

    On the Relationship between the Uniqueness of the Moonshine Module and Monstrous Moonshine

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    We consider the relationship between the conjectured uniqueness of the Moonshine Module, Vâ™®{\cal V}^\natural, and Monstrous Moonshine, the genus zero property of the modular invariance group for each Monster group Thompson series. We first discuss a family of possible ZnZ_n meromorphic orbifold constructions of Vâ™®{\cal V}^\natural based on automorphisms of the Leech lattice compactified bosonic string. We reproduce the Thompson series for all 51 non-Fricke classes of the Monster group MM together with a new relationship between the centralisers of these classes and 51 corresponding Conway group centralisers (generalising a well-known relationship for 5 such classes). Assuming that Vâ™®{\cal V}^\natural is unique, we then consider meromorphic orbifoldings of Vâ™®{\cal V}^\natural and show that Monstrous Moonshine holds if and only if the only meromorphic orbifoldings of Vâ™®{\cal V}^\natural give Vâ™®{\cal V}^\natural itself or the Leech theory. This constraint on the meromorphic orbifoldings of Vâ™®{\cal V}^\natural therefore relates Monstrous Moonshine to the uniqueness of Vâ™®{\cal V}^\natural in a new way.Comment: 53 pages, PlainTex, DIAS-STP-93-0

    Dynamic Posterior Instability Test: A New Test for Posterior Glenohumeral Instability

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    BACKGROUND: Recurrent posterior shoulder instability has become an increasingly recognized cause of shoulder disability, especially among athletes. The presentation can be vague and therefore its clinical diagnosis is often overlooked. Few diagnostic tests exist and these tests are difficult to perform in an anxious and apprehensive patient. Many also lack high specificity and do not effectively distinguish posterior labral tears from other shoulder pathologies. As a result, the authors worked to develop a new test, the dynamic posterior instability test (DPIT). The purpose of this study was to describe the DPIT as well as a modified DPIT test and to evaluate the accuracy of these tests in detecting posterior labral pathology. It was hypothesized that the dynamic posterior instability test (DPIT) would improve accuracy in the evaluation of posterior labral tears. METHODS: For a 9-month period, the DPIT and modified DPIT tests were performed on all patients evaluated for posterior instability of the shoulder. The records of all patients who had undergone a posterior labral repair (type VIII SLAP and posterior labral tears) were reviewed. The results of the DPIT and modified DPIT tests were compared to intra-operative findings. Anterior glenohumeral instability patients were also evaluated with these tests to serve as a control. RESULTS: Fifty-one patients had a positive and 3 patients had a negative DPIT test. Of the anterior instability patients, there was 1 positive and 19 negative test results. The sensitivity of the DPIT test was 94.4%, specificity 95%, the positive predictive value 0.98, and the negative predictive value 0.86. The results of the modified DPIT were the same as the DPIT test. CONCLUSIONS: The DPIT and modified DPIT tests provide a valuable new tool when combined with history and other physical examination findings improve the accuracy of diagnosis of posterior shoulder instability

    A malaria parasite subtilisin propeptide-like protein is a potent inhibitor of the egress protease SUB1.

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    Subtilisin-like serine peptidases (subtilases) play important roles in the life cycle of many organisms, including the protozoan parasites that are the causative agent of malaria, Plasmodium spp. As with other peptidases, subtilase proteolytic activity has to be tightly regulated in order to prevent potentially deleterious uncontrolled protein degradation. Maturation of most subtilases requires the presence of an N-terminal propeptide that facilitates folding of the catalytic domain. Following its proteolytic cleavage, the propeptide acts as a transient, tightly bound inhibitor until its eventual complete removal to generate active protease. Here we report the identification of a stand-alone malaria parasite propeptide-like protein, called SUB1-ProM, encoded by a conserved gene that lies in a highly syntenic locus adjacent to three of the four subtilisin-like genes in the Plasmodium genome. Template-based modelling and ab initio structure prediction showed that the SUB1-ProM core structure is most similar to the X-ray crystal structure of the propeptide of SUB1, an essential parasite subtilase that is discharged into the parasitophorous vacuole (PV) to trigger parasite release (egress) from infected host cells. Recombinant Plasmodium falciparum SUB1-ProM was found to be a fast-binding, potent inhibitor of P. falciparum SUB1, but not of the only other essential blood-stage parasite subtilase, SUB2, or of other proteases examined. Mass-spectrometry and immunofluorescence showed that SUB1-ProM is expressed in the PV of blood stage P. falciparum, where it may act as an endogenous inhibitor to regulate SUB1 activity in the parasite
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