554 research outputs found

    Word Processors with Line-Wrap: Cascading, Self-Organized Criticality, Random Walks, Diffusion, Predictability

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    We examine the line-wrap feature of text processors and show that adding characters to previously formatted lines leads to the cascading of words to subsequent lines and forms a state of self-organized criticality. We show the connection to one-dimensional random walks and diffusion problems, and we examine the predictability of catastrophic cascades.Comment: 6 pages, LaTeX with RevTeX package, 4 postscript figures appende

    How Low Is Too Low? Postpartum Hemorrhage Risk among Women with Thrombocytopenia

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    Objective To estimate the association between severity of thrombocytopenia and postpartum hemorrhage. Study Design We performed a secondary analysis of a prospective cohort of women delivering by cesarean or vaginal birth after cesarean conducted by the National Institute of Child Health and Human Development (NICHD) Maternal-Fetal Medicine Unit. Women delivering ≥ 20 weeks with platelets < 400,000/mL were included. Thrombocytopenia was defined as predelivery platelets of < 150,000/mL. Primary outcomes were (1) laboratory evidence of hemorrhage, defined as a decrease in hemoglobin ≥ 4 mg/dL and (2) clinical evidence of hemorrhage, a composite of atony, transfusion, coagulopathy, hysterectomy, laparotomy, or intensive care unit admission. Odds ratios were calculated for primary outcomes using thrombocytopenia as a dichotomous and ordinal variable. Results A total of 54,597 women were included; 5,611 (10.3%) had antepartum thrombocytopenia, 1,976 (3.6%) women had laboratory evidence of hemorrhage, and 3,862 (7.1%) had clinical evidence of hemorrhage. Thrombocytopenia was associated with both laboratory evidence of hemorrhage (adjusted odds ratio [aOR]: 1.60, 95% CI: 1.38-1.86) and clinical evidence of hemorrhage (aOR: 1.68, 95% CI: 1.52-1.83). The odds of laboratory and clinical evidence of hemorrhage increased incrementally with severity of thrombocytopenia. Conclusion Thrombocytopenia is associated with both laboratory and clinical evidence of hemorrhage; risk increases dramatically as platelet count decreases

    A Method for Assaying Deubiquitinating Enzymes

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    A general method for the assay of deubiquitinating enzymes was described in detail using (125)I-labeled ubiquitin-fused αNH-MHISPPEPESEEEEEHYC (referred to as Ub-PESTc) as a substrate. Since the tyrosine residue in the PESTc portion of the fusion protein was almost exclusively radioiodinated under a mild labeling condition, such as using IODO-BEADS, the enzymes could be assayed directly by simple measurement of the radioactivity released into acid soluble products. Using this assay protocol, we could purify six deubiquitinating enzymes from chick skeletal muscle and yeast and compare their specific activities. Since the extracts of E. coli showed little or no activity against the substrate, the assay protocol should be useful for identification and purification of eukaryotic deubiquitinating enzymes cloned and expressed in the cells

    Hybrid stars with the color dielectric and the MIT bag models

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    We study the hadron-quark phase transition in the interior of neutron stars (NS). For the hadronic sector, we use a microscopic equation of state (EOS) involving nucleons and hyperons derived within the Brueckner-Bethe-Goldstone many-body theory, with realistic two-body and three-body forces. For the description of quark matter, we employ both the MIT bag model with a density dependent bag constant, and the color dielectric model. We calculate the structure of NS interiors with the EOS comprising both phases, and we find that the NS maximum masses are never larger than 1.7 solar masses, no matter the model chosen for describing the pure quark phase.Comment: 11 pages, 5 figures, submitted to Phys. Rev.

    Thermodynamics of Trapped Imbalanced Fermi Gases at Unitarity

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    We present a theory for the low-temperature properties of a resonantly interacting Fermi mixture in a trap, that goes beyond the local-density approximation. The theory corresponds essentially to a Landau-Ginzburg-like approach that includes self-energy effects to account for the strong interactions at unitarity. We show diagrammatically how these self-energy effects arise from fluctuations in the superfluid order parameter. Gradient terms of the order parameter are included to account for inhomogeneities. This approach incorporates the state-of-the-art knowledge of the homogeneous mixture with a population imbalance exactly and gives good agreement with the experimental density profiles of Shin et al. [Nature 451, 689 (2008)]. This allows us to calculate the universal surface tension of the interface between the equal-density superfluid and the partially polarized normal state of the mixture. We also discuss the possibility of a metastable state to explain the deformation of the superfluid core that is seen in the experiment of Partridge et al. [Science 311, 503 (2006)].Comment: 26 pages, 7 figures, contribution to Lecture Notes in Physics "BCS-BEC crossover and the Unitary Fermi Gas" edited by W. Zwerge

    Management of pregnancy and survival of infants with trisomy 13 or trisomy 18

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    Objective The objective of this study was to describe antenatal/intrapartum management and survival of liveborn infants with known trisomy 13 (T13) or trisomy 18 (T18) based on planned neonatal care. Study Design This is a retrospective cohort study of singleton pregnancies complicated by T13/T18 at a tertiary center from 2004 to 2015. We included pregnancies with antenatal or neonatal cytogenetic T13/T18 diagnosis and excluded those which were terminated or had a fetal demise < 20 weeks. We compared antenatal/intrapartum management and neonatal survival by planned neonatal care, defined as either neonatal intervention (INT), including neonatal cardiopulmonary resuscitative measures or comfort care (CC) without resuscitative measures. Results In this study, 32 women (10 with T13 and 22 with T18) met study criteria; 12 (38%) elected INT and 20 (62%) CC. Compared with those who elected INT, women who elected CC were more likely to undergo elective induction (40 vs. 0%, p = 0.01), have an intrapartum stillbirth (0 vs. 32%, p = 0.14), and deliver vaginally (25 vs. 63%, p < 0.01). In neonatal survival analysis (n = 26), median survival was longer in the INT group compared with CC group (64 days [interquartile range, IQR: 2, 155) vs. 3 days [IQR]: 0.3, 42), p = 0.28), but survival to hospital discharge was similar (53 vs. 57%, p = 0.95). Conclusion Regardless of desired level of neonatal INT, many women who continue pregnancies complicated by T13/18 have infants who survive beyond hospital discharge

    The hadron-quark phase transition in dense matter and neutron stars

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    We study the hadron-quark phase transition in the interior of neutron stars (NS's). We calculate the equation of state (EOS) of hadronic matter using the Brueckner-Bethe-Goldstone formalism with realistic two-body and three-body forces, as well as a relativistic mean field model. For quark matter we employ the MIT bag model constraining the bag constant by using the indications coming from the recent experimental results obtained at the CERN SPS on the formation of a quark-gluon plasma. We find necessary to introduce a density dependent bag parameter, and the corresponding consistent thermodynamical formalism. We calculate the structure of NS interiors with the EOS comprising both phases, and we find that the NS maximum masses fall in a relatively narrow interval, 1.4MMmax1.7M1.4 M_\odot \leq M_{\rm max} \leq 1.7 M_\odot. The precise value of the maximum mass turns out to be only weakly correlated with the value of the energy density at the assumed transition point in nearly symmetric nuclear matter.Comment: 25 pages, Revtex4, 16 figures included as postscrip

    Itinerant Ferromagnetism in the Periodic Anderson Model

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    We introduce a novel mechanism for itinerant ferromagnetism, based on a simple two-band model. The model includes an uncorrelated and dispersive band hybridized with a second band which is narrow and correlated. The simplest Hamiltonian containing these ingredients is the Periodic Anderson Model (PAM). Using quantum Monte Carlo and analytical methods, we show that the PAM and an extension of it contain the new mechanism and exhibit a non-saturated ferromagnetic ground state in the intermediate valence regime. We propose that the mechanism, which does not assume an intra atomic Hund's coupling, is present in both the iron group and in some f electron compounds like Ce(Rh_{1-x} Ru_x)_3 B_2, La_x Ce_{1-x} Rh_3 B_2 and the uranium monochalcogenides US, USe, and UTe

    Probing Lorentz and CPT violation with space-based experiments

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    Space-based experiments offer sensitivity to numerous unmeasured effects involving Lorentz and CPT violation. We provide a classification of clock sensitivities and present explicit expressions for time variations arising in such experiments from nonzero coefficients in the Lorentz- and CPT-violating Standard-Model Extension.Comment: 15 page
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