384 research outputs found

    Trends in Characteristics of Patients Listed for Liver Transplantation Will Lead to Higher Rates of Waitlist Removal Due to Clinical Deterioration

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    BACKGROUND: Changes in the epidemiology of end-stage liver disease may lead to increased risk of dropout from the liver transplant waitlist. Anticipating the future of liver transplant waitlist characteristics is vital when considering organ allocation policy. METHODS: We performed a discrete event simulation to forecast patient characteristics and rate of waitlist dropout. Estimates were simulated from 2015 to 2025. The model was informed by data from the Organ Procurement and Transplant Network, 2003 to 2014. National data are estimated along with forecasts for 2 regions. RESULTS: Nonalcoholic steatohepatitis will increase from 18% of waitlist additions to 22% by 2025. Hepatitis C will fall from 30% to 21%. Listings over age 60 years will increase from 36% to 48%. The hazard of dropout will increase from 41% to 46% nationally. Wait times for transplant for patients listed with a Model for End-Stage Liver Disease (MELD) between 22 and 27 will double. Region 5, which transplants at relatively higher MELD scores, will experience an increase from 53% to 64% waitlist dropout. Region 11, which transplants at lower MELD scores, will have an increase in waitlist dropout from 30% to 44%. CONCLUSIONS: The liver transplant waitlist size will remain static over the next decade due to patient dropout. Liver transplant candidates will be older, more likely to have nonalcoholic steatohepatitis and will wait for transplantation longer even when listed at a competitive MELD score. There will continue to be significant heterogeneity among transplant regions where some patients will be more likely to drop out of the waitlist than receive a transplant

    Declining liver graft quality threatens the future of liver transplantation in the United States

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    National liver transplantation (LT) volume has declined since 2006, in part because of worsening donor organ quality. Trends that degrade organ quality are expected to continue over the next 2 decades. We used the United Network for Organ Sharing (UNOS) database to inform a 20-year discrete event simulation estimating LT volume from 2010 to 2030. Data to inform the model were obtained from deceased organ donors between 2000 and 2009. If donor liver utilization practices remain constant, utilization will fall from 78% to 44% by 2030, resulting in 2230 fewer LTs. If transplant centers increase their risk tolerance for marginal grafts, utilization would decrease to 48%. The institution of "opt-out" organ donation policies to increase the donor pool would still result in 1380 to 1866 fewer transplants. Ex vivo perfusion techniques that increase the use of marginal donor livers may stabilize LT volume. Otherwise, the number of LTs in the United States will decrease substantially over the next 15 years. In conclusion, the transplant community will need to accept inferior grafts and potentially worse posttransplant outcomes and/or develop new strategies for increasing organ donation and utilization in order to maintain the number of LTs at the current level

    Remarks on Semileptonic B and D Decays into Orbitally Excited Mesons

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    We have obtained the differential decay rate and calculated the branching ratios of the exclusive semileptonic decays B(D)XlνB(D) \to Xl\nu, where XX is a p-wave meson, using the nonrelativistic ISGW quark model. Our results are compared with the predictions of the ISGW2 model. We have computed some branching ratios that were not reported or were reported with 0.00 in this model. For example, we find that Br(BcBs20ˉlνˉ)=4.03×105Br(B_c^- \to \bar{B_{s2}^{*0}}l^-\bar{\nu}) = 4.03 \times 10^{-5}, Br(BcB20ˉlνˉ)=3.65×106Br(B_c^- \to \bar{B_2^{*0}}l^- \bar{\nu}) =3.65 \times 10^{-6} and Br(Ds+f2l+ν)=2.7×105Br(D_s^+ \to f_2l^+\nu) = 2.7 \times 10^{-5}, which seems to be at the reach of forthcoming experiments. Furthermore, we have classified the Bu,d,sTlνB_{u,d,s} \to Tl\nu decays in two groups and compared the semileptonic and nonleptonic decays including a tensor meson in the final state.Comment: 11 pages, LaTe

    Rational F-Theory GUTs without exotics

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    We construct F-theory GUT models without exotic matter, leading to the MSSM matter spectrum with potential singlet extensions. The interplay of engineering explicit geometric setups, absence of four-dimensional anomalies, and realistic phenomenology of the couplings places severe constraints on the allowed local models in a given geometry. In constructions based on the spectral cover we find no model satisfying all these requirements. We then provide a survey of models with additional U(1) symmetries arising from rational sections of the elliptic fibration in toric constructions and obtain phenomenologically appealing models based on SU(5) tops. Furthermore we perform a bottom-up exploration beyond the toric section constructions discussed in the literature so far and identify benchmark models passing all our criteria, which can serve as a guideline for future geometric engineering.Comment: 27 Pages, 1 Figur

    Non-supersymmetric heterotic model building

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    We investigate orbifold and smooth Calabi-Yau compactifications of the non-supersymmetric heterotic SO(16)xSO(16) string. We focus on such Calabi-Yau backgrounds in order to recycle commonly employed techniques, like index theorems and cohomology theory, to determine both the fermionic and bosonic 4D spectra. We argue that the N=0 theory never leads to tachyons on smooth Calabi-Yaus in the large volume approximation. As twisted tachyons may arise on certain singular orbifolds, we conjecture that such tachyonic states are lifted in the full blow-up. We perform model searches on selected orbifold geometries. In particular, we construct an explicit example of a Standard Model-like theory with three generations and a single Higgs field.Comment: 1+30 pages latex, 11 tables; v2: references and minor revisions added, matches version published in JHE

    The words leader/líder and their resonances in an Italo-Latin American multinational corporation

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    © 2017, © The Author(s) 2017. The problems of ‘lost in translation’ are well known. Yet some terms of English managerial vocabulary, which are perfectly translatable in other languages, remain untranslated. One explanation of this phenomenon is what Linguistic anthropology call negative semantic resonances. Semantic resonances focused on the issue of which meanings can or cannot be expressed by a single word in different cultures. In this paper, based on an organisational ethnography of Latin American expatriates working for an Italo-Latin-American multinational corporation (Tubworld), we analyse the resonances of the word leader/líder and director, direttore, capo, guida, coordinador, caudillo among a group of expatriates; all Italian, Spanish or multilingual speakers who use English as a second language in their everyday interactions. The paper explains how the different uses contribute to create a meaning of what a leader should and should not be; someone who leads without leading, sometimes a manager. The authors, an Italian native speaker who learnt Spanish during childhood and use English as his everyday language and a Spanish native speaker, argue that Italian or Spanish speakers not only avoid the words duce and caudillo (the vernacular vocabulary for leader, not in use due to the political and cultural meaning) but also the word leader/líder itself, as it resonate to the other two (violent, authoritarian, autocratic, antidemocratic leadership) but furthermore because the word, a lexical loan from English, failed to encapsulate the complexity of leading multilingual organisations like Tubworld

    Colorectal adenomas contain multiple somatic mutations that do not coincide with synchronous adenocarcinoma specimens

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    We have performed a comparative ultrasequencing study of multiple colorectal lesions obtained simultaneously from four patients. Our data show that benign lesions (adenomatous or hyperplastic polyps) contain a high mutational load. Additionally multiple synchronous colorectal lesions show non overlapping mutational signatures highlighting the degree of heterogeneity between multiple specimens in the same patient. Observations in these cases imply that considering not only the number of mutations but an effective oncogenic combination of mutations can determine the malignant progression of colorectal lesions

    No association between polymorphisms/haplotypes of the vascular endothelial growth factor gene and preeclampsia

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    <p>Abstract</p> <p>Background</p> <p>Preeclampsia (PE) is the first worldwide cause of death in pregnant women, intra-uterine growth retardation, and fetal prematurity. Some vascular endothelial grown factor gene (<it>VEGF</it>) polymorphisms have been associated to PE and other pregnancy disturbances. We evaluated the associations between <it>VEGF </it>genotypes/haplotypes and PE in Mexican women.</p> <p>Methods</p> <p>164 pregnant women were enrolled in a case-control study (78 cases and 86 normotensive pregnant controls). The rs699947 (-2578C/A), rs1570360 (-1154G/A), rs2010963 (+405G/C), and rs25648 (-7C/T), <it>VEGF </it>variants were discriminated using Polymerase Chain Reaction - Restriction Fragment Length Polymorphism (PCR-RFLP) methods or Taqman single nucleotide polymorphism (SNP) assays.</p> <p>Results</p> <p>The proportions of the minor allele for rs699947, rs1570360, rs2010963, and rs25648 <it>VEGF </it>SNPs were 0.33, 0.2, 0.39, and 0.17 in controls, and 0.39, 0.23, 0.41, and 0.15 in cases, respectively (<it>P </it>values > 0.05). The most frequent haplotypes of rs699947, rs1570360, rs2010963, and rs25648 <it>VEGF </it>SNPs, were C-G-C-C and C-G-G-C with frequencies of 0.39, 0.21 in cases and 0.37, 0.25 in controls, respectively (<it>P </it>values > 0.05)</p> <p>Conclusion</p> <p>There was no evidence of an association between <it>VEGF </it>alleles, genotypes, or haplotypes frequencies and PE in our study.</p

    Analyses of 32 Loci Clarify Phylogenetic Relationships among Trypanosoma cruzi Lineages and Support a Single Hybridization prior to Human Contact

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    Trypanosoma cruzi is the protozoan parasite that causes Chagas disease, a major health problem in Latin America. The genetic diversity of this parasite has been traditionally divided in two major groups: T. cruzi I and II, which can be further divided in six major genetic subdivisions (subgroups TcI-TcVI). T. cruzi I and II seem to differ in important biological characteristics, and are thought to represent a natural division relevant for epidemiological studies and development of prophylaxis. Having a correct reconstruction of the evolutionary history of T. cruzi is essential for understanding the potential connection between the genetic and phenotypic variability of T. cruzi with the different manifestations of Chagas disease. Here we present results from a comprehensive phylogenetic analysis of T. cruzi using more than 26 Kb of aligned sequence data. We show strong evidence that T. cruzi II (TcII-VI) is not a natural evolutionary group but a paraphyletic lineage and that all major lineages of T. cruzi evolved recently (<3 million years ago [mya]). Furthermore, the sequence data is consistent with one major hybridization event having occurred in this species recently (< 1 mya) but well before T. cruzi entered in contact with humans in South America
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