98 research outputs found

    A critical-density closed Universe in Brans-Dicke theory

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    In a Brans-Dicke (BD) cosmological model, the energy density associated with some scalar field decreases as \displaystyle a^{{-2}(\frac{\omega_{o}+ {\frac12}%}{\omega_{o}+1})} with the scale factor a(t)a(t) of the Universe, giving a matter with an Equation of state p=1/3(2+ωo1+ωo)ρ\displaystyle p=-{1/3}(\frac{2+\omega_{o}}{1+\omega_{o}}) \rho . In this model, the Universe could be closed but still have a nonrelativistic-matter density corresponding to its critical value, Ωo=1\Omega_{o}=1. Different cosmological expressions, such as, luminosity distance, angular diameter, number count and ratio of the redshift tickness-angular size, are determined in terms of the redshift for this model.Comment: To appear in MNRAS, 7 pages, 5 eps figure

    The Incremental Cooperative Design of Preventive Healthcare Networks

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    This document is the Accepted Manuscript version of the following article: Soheil Davari, 'The incremental cooperative design of preventive healthcare networks', Annals of Operations Research, first published online 27 June 2017. Under embargo. Embargo end date: 27 June 2018. The final publication is available at Springer via http://dx.doi.org/10.1007/s10479-017-2569-1.In the Preventive Healthcare Network Design Problem (PHNDP), one seeks to locate facilities in a way that the uptake of services is maximised given certain constraints such as congestion considerations. We introduce the incremental and cooperative version of the problem, IC-PHNDP for short, in which facilities are added incrementally to the network (one at a time), contributing to the service levels. We first develop a general non-linear model of this problem and then present a method to make it linear. As the problem is of a combinatorial nature, an efficient Variable Neighbourhood Search (VNS) algorithm is proposed to solve it. In order to gain insight into the problem, the computational studies were performed with randomly generated instances of different settings. Results clearly show that VNS performs well in solving IC-PHNDP with errors not more than 1.54%.Peer reviewe

    An instructive role for Interleukin-7 receptor α in the development of human B-cell precursor leukemia

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    © The Author(s) 2022. Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.Kinase signaling fuels growth of B-cell precursor acute lymphoblastic leukemia (BCP-ALL). Yet its role in leukemia initiation is unclear and has not been shown in primary human hematopoietic cells. We previously described activating mutations in interleukin-7 receptor alpha (IL7RA) in poor-prognosis "ph-like" BCP-ALL. Here we show that expression of activated mutant IL7RA in human CD34+ hematopoietic stem and progenitor cells induces a preleukemic state in transplanted immunodeficient NOD/LtSz-scid IL2Rγnull mice, characterized by persistence of self-renewing Pro-B cells with non-productive V(D)J gene rearrangements. Preleukemic CD34+CD10highCD19+ cells evolve into BCP-ALL with spontaneously acquired Cyclin Dependent Kinase Inhibitor 2 A (CDKN2A) deletions, as commonly observed in primary human BCP-ALL. CRISPR mediated gene silencing of CDKN2A in primary human CD34+ cells transduced with activated IL7RA results in robust development of BCP-ALLs in-vivo. Thus, we demonstrate that constitutive activation of IL7RA can initiate preleukemia in primary human hematopoietic progenitors and cooperates with CDKN2A silencing in progression into BCP-ALL.This work was supported by the Israel Science Foundation (# 1178/12 to S.I.), Children with Cancer (UK) (S.I. and T.E.), Swiss Bridge Foundation (S.I.), WLBH Foundation (S.I.), Waxman Cancer Research Foundation (S.I.), US–Israel Binational Science Foundation, Israeli health ministry ERA-NET program (#CANCER11-FP-127 to S.I.), Hans Neufeld Stiftung, the International Collaboration Grant from the Jacki and Bruce Barron Cancer Research Scholars’ Program, a partnership of the Israel Cancer Research Fund and City of Hope (S.I. grants # 00161), the Nevzlin Genomic Center for Precision Medicine in Schneider Children’s Medical Center of Israel, The European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 813091 (S.I.) and the Israel Childhood Cancer Foundation (S.I.). I.G. was partially supported by Israeli ministry of Immigrant Absorption.info:eu-repo/semantics/publishedVersio

    A phase I trial of S-1 with concurrent radiotherapy for locally advanced pancreatic cancer

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    This study investigated the maximum tolerated dose of S-1 based on the frequency of its dose-limiting toxicities (DLT) with concurrent radiotherapy in patients with locally advanced pancreatic cancer. S-1 was administered orally at escalating doses from 50 to 80 mg m−2 b.i.d. on the day of irradiation during radiotherapy. Radiation therapy was delivered through four fields as a total dose of 50.4 Gy in 28 fractions over 5.5 weeks, and no prophylactic nodal irradiation was given. Twenty-one patients (50 three; 60 five; 70 six; 80 mg m−2 seven patients) were enrolled in this trial. At a dose of 70 mg m−2 S-1, two of six patients demonstrated DLT involving grade 3 nausea and vomiting and grade 3 haemorrhagic gastritis, whereas no patients at doses other than 70 mg m−2 demonstrated any sign of DLT. Among the 21 enrolled patients, four (19.0%) showed a partial response. The median progression-free survival time and median survival time for the patients overall were 8.9 and 11.0 months, respectively. The recommended dose of S-1 therapy with concurrent radiotherapy is 80 mg m−2 day−1. A multi-institutional phase II trial of this regimen in patients with locally advanced pancreatic cancer is now underway

    Dust environment and dynamical history of a sample of short-period comets: II. 81P/Wild 2 and 103P/Hartley 2

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    Aims. This paper is a continuation of the first paper in this series, where we presented an extended study of the dust environment of a sample of short-period comets and their dynamical history. On this occasion, we focus on comets 81P/Wild 2 and 103P/Hartley 2, which are of special interest as targets of the spacecraft missions Stardust and EPOXI. Methods. As in the previous study, we used two sets of observational data: a set of images, acquired at Sierra Nevada and Lulin observatories, and the Afρ data as a function of the heliocentric distance provided by the amateur astronomical association Cometas-Obs. The dust environment of comets (dust loss rate, ejection velocities, and size distribution of the particles) was derived from our Monte Carlo dust tail code. To determine their dynamical history we used the numerical integrator Mercury 6.2 to ascertain the time spent by these objects in the Jupiter family Comet region. Results. From the dust analysis, we conclude that both 81P/Wild 2 and 103P/Hartley 2 are dusty comets, with an annual dust production rate of 2.8 × 109 kg yr-1 and (0.4-1.5) × 109 kg yr-1, respectively. From the dynamical analysis, we determined their time spent in the Jupiter family Comet region as ~40 yr in the case of 81P/Wild 2 and ~1000 yr for comet 103P/Hartley 2. These results imply that 81P/Wild 2 is the youngest and the most active comet of the eleven short-period comets studied so far, which tends to favor the correlation between the time spent in JFCs region and the comet activity previously discussed

    25th annual computational neuroscience meeting: CNS-2016

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    The same neuron may play different functional roles in the neural circuits to which it belongs. For example, neurons in the Tritonia pedal ganglia may participate in variable phases of the swim motor rhythms [1]. While such neuronal functional variability is likely to play a major role the delivery of the functionality of neural systems, it is difficult to study it in most nervous systems. We work on the pyloric rhythm network of the crustacean stomatogastric ganglion (STG) [2]. Typically network models of the STG treat neurons of the same functional type as a single model neuron (e.g. PD neurons), assuming the same conductance parameters for these neurons and implying their synchronous firing [3, 4]. However, simultaneous recording of PD neurons shows differences between the timings of spikes of these neurons. This may indicate functional variability of these neurons. Here we modelled separately the two PD neurons of the STG in a multi-neuron model of the pyloric network. Our neuron models comply with known correlations between conductance parameters of ionic currents. Our results reproduce the experimental finding of increasing spike time distance between spikes originating from the two model PD neurons during their synchronised burst phase. The PD neuron with the larger calcium conductance generates its spikes before the other PD neuron. Larger potassium conductance values in the follower neuron imply longer delays between spikes, see Fig. 17.Neuromodulators change the conductance parameters of neurons and maintain the ratios of these parameters [5]. Our results show that such changes may shift the individual contribution of two PD neurons to the PD-phase of the pyloric rhythm altering their functionality within this rhythm. Our work paves the way towards an accessible experimental and computational framework for the analysis of the mechanisms and impact of functional variability of neurons within the neural circuits to which they belong
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