551 research outputs found

    The Romano-Parthian Cold War: Julio-Claudian Foreign Policy in the First Century CE and Tacitus\u27 Annales

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    Many ancient and modern authors view the first century CE as an unprecedented era of peace and security for the Roman Empire. These writers often identify the Roman emperor Augustus’ diplomatic settlement with Parthia (ca. 20 BCE) as an important cornerstone of the Pax Romana. But while the two ancient superpowers may have averted large-scale conflicts, Romano-Parthian relations under Augustus and the Julio-Claudians were never entirely uneventful or especially peaceful. Whether the Parthian Empire posed a real threat to Rome’s internal security or not, Julio-Claudian emperors developed elaborate “cold war”-style strategies to keep Rome’s eastern rival in check. Augustus and his successors frequently dispatched dynastic pretenders to destabilize Parthia’s Arsacid regime and fought hard to maintain the Kingdom of Armenia as a strategic buffer-state. These strategies, for the most part, preserved the integrity of Rome’s eastern provinces for more than a century; however, that security came at some cost to the Julio-Claudians’ reputation at home. Despite the diplomatic strategy’s general effectiveness, Roman critics viewed the Julio-Claudians’ Parthian strategy with disdain—as a poor substitute for a more direct, more “Roman” militaristic approach to the eastern frontier. To better understand these critics’ objections, this study focuses on the Roman historian Tacitus’ Annales. Tacitus’ work, composed either just prior to or during Trajan’s Parthian War, contains a series of extensive passages dedicated to Romano-Parthian affairs in the first century. In the past, some Tacitean scholars have dismissed these eastern episodes as aimless digressions that bear no relevance for the historian’s overall purpose. Careful analysis reveals, however, that these passages, in fact, form a highly schematized literary argument which calls into question the wisdom of the Julio-Claudians’ Parthian strategy. Undermining the Julio-Claudians’ foreign policy allows Tacitus to portray Trajan’s Parthian War as the proper course of action all Roman emperors should adopt in terms of the eastern frontier

    The Anderson Model as a Matrix Model

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    In this paper we describe a strategy to study the Anderson model of an electron in a random potential at weak coupling by a renormalization group analysis. There is an interesting technical analogy between this problem and the theory of random matrices. In d=2 the random matrices which appear are approximately of the free type well known to physicists and mathematicians, and their asymptotic eigenvalue distribution is therefore simply Wigner's law. However in d=3 the natural random matrices that appear have non-trivial constraints of a geometrical origin. It would be interesting to develop a general theory of these constrained random matrices, which presumably play an interesting role for many non-integrable problems related to diffusion. We present a first step in this direction, namely a rigorous bound on the tail of the eigenvalue distribution of such objects based on large deviation and graphical estimates. This bound allows to prove regularity and decay properties of the averaged Green's functions and the density of states for a three dimensional model with a thin conducting band and an energy close to the border of the band, for sufficiently small coupling constant.Comment: 23 pages, LateX, ps file available at http://cpth.polytechnique.fr/cpth/rivass/articles.htm

    TALEN-Mediated Inactivation of PD-1 in Tumor-Reactive Lymphocytes Promotes Intratumoral T-cell Persistence and Rejection of Established Tumors

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    Despite the promising efficacy of adoptive cell therapies (ACT) in melanoma, complete response rates remain relatively low and outcomes in other cancers are less impressive. The immunosuppressive nature of the tumor microenvironment and the expression of immune-inhibitory ligands, such as PD-L1/CD274 by the tumor and stroma are considered key factors limiting efficacy. The addition of checkpoint inhibitors (CPI) to ACT protocols bypasses some mechanisms of immunosuppression, but associated toxicities remain a significant concern. To overcome PD-L1–mediated immunosuppression and reduce CPI-associated toxicities, we used TALEN technology to render tumor-reactive T cells resistant to PD-1 signaling. Here, we demonstrate that inactivation of the PD-1 gene in melanoma-reactive CD8+ T cells and in fibrosarcoma-reactive polyclonal T cells enhanced the persistence of PD-1 gene-modified T cells at the tumor site and increased tumor control. These results illustrate the feasibility and potency of approaches incorporating advanced gene-editing technologies into ACT protocols to silence immune checkpoints as a strategy to overcome locally active immune escape pathways

    Signature of stripe pinning in optical conductivity

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    The response of charge stripes to an external electric field applied perpendicular to the stripe direction is studied within a diagrammatic approach for both weak and strong pinning by random impurities. The sound-like mode of the stripes described as elastic strings moves to finite frequency due to impurity pinning. By calculating the optical conductivity we determine this characteristic energy scale for both a single stripe and an array of interacting stripes. The results explain the anomalous far-infrared peak observed recently in optical-conductivity measurements on cuprates.Comment: Revised version, to appear in Phys. Rev.

    Similarity of slow stripe fluctations between Sr-doped cuprates and oxygen-doped nickelates

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    Stripe fluctuations in La2NiO4.17 have been studied by 139La NMR using the field and temperature dependence of the linewidth and relaxation rates. In the formation process of the stripes the NMR line intensity is maximal below 230K, starts to diminish around 140K, disappears around 50K and recovers at 4K. These results are shown to be consistent with, but completely complementary to neutron measurements, and to be generic for oxygen doped nickelates and underdoped cuprates.Comment: 4 pages including 4 figure

    Sonogashira diversification of unprotected halotryptophans, halotryptophan containing tripeptides; and generation of a new to nature bromo-natural product and its diversification in water

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    The blending together of synthetic chemistry with natural product biosynthesis represents a potentially powerful approach to synthesis; to enable this, further synthetic tools and methodologies are needed. To this end, we have explored the first Sonogashira cross-coupling to halotryptophans in water. Broad reaction scope is demonstrated and we have explored the limits of the scope of the reaction. We have demonstrated this methodology to work excellently in the modification of model tripeptides. Furthermore, through precursor directed biosynthesis, we have generated for the first time a new to nature brominated natural product bromo-cystargamide, and demonstrated the applicability of our reaction conditions to modify this novel metabolite

    Gene editing of PKLR gene in human hematopoietic progenitors through 5' and 3' UTR modified TALEN mRNA

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    TheauthorswouldliketothankMiguelA.MartinforthecarefulmaintenanceofNSGmice,andRebecaSa ́nchezandOmairaAlberquillafortheirtechnicalassistanceinflowcytometry.TheauthorsalsothankFundacio ́n Botı ́n forpromotingtranslationalresearchattheHemato-poieticInnovativeTherapiesDivisionoftheCIEMATPyruvate Kinase Deficiency (PKD) is a rare erythroid metabolic disease caused by mutations in the PKLR gene, which encodes the erythroid specific Pyruvate Kinase enzyme. Erythrocytes from PKD patients show an energetic imbalance and are susceptible to hemolysis. Gene editing of hematopoietic stem cells (HSCs) would provide a therapeutic benefit and improve safety of gene therapy approaches to treat PKD patients. In previous studies, we established a gene editing protocol that corrected the PKD phenotype of PKD-iPSC lines through a TALEN mediated homologous recombination strategy. With the goal of moving toward more clinically relevant stem cells, we aim at editing the PKLR gene in primary human hematopoietic progenitors and hematopoietic stem cells (HPSCs). After nucleofection of the gene editing tools and selection with puromycin, up to 96% colony forming units showed precise integration. However, a low yield of gene edited HPSCs was associated to the procedure. To reduce toxicity while increasing efficacy, we worked on i) optimizing gene editing tools and ii) defining optimal expansion and selection times. Different versions of specific nucleases (TALEN and CRISPR-Cas9) were compared. TALEN mRNAs with 5' and 3' added motifs to increase RNA stability were the most efficient nucleases to obtain high gene editing frequency and low toxicity. Shortening ex vivo manipulation did not reduce the efficiency of homologous recombination and preserved the hematopoietic progenitor potential of the nucleofected HPSCs. Lastly, a very low level of gene edited HPSCs were detected after engraftment in immunodeficient (NSG) mice. Overall, we showed that gene editing of the PKLR gene in HPSCs is feasible, although further improvements must to be done before the clinical use of the gene editing to correct PKD.S

    Mid-Infrared Conductivity from Mid-Gap States Associated with Charge Stripes

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    The optical conductivity of La(2-x)Sr(x)NiO(4) has been interpreted in various ways, but so far the proposed interpretations have neglected the fact that the holes doped into the NiO(2) planes order in diagonal stripes, as established by neutron and X-ray scattering. Here we present a study of optical conductivity in La(2)NiO(4+d) with d=2/15, a material in which the charge stripes order three-dimensionally. We show that the conductivity can be decomposed into two components, a mid-infrared peak that we attribute to transitions from the filled valence band into empty mid-gap states associated with the stripes, and a Drude peak that appears at higher temperatures as carriers are thermally excited into the mid-gap states. The shift of the mid-IR peak to lower energy with increasing temperature is explained in terms of the Franck-Condon effect. The relevance of these results to understanding the optical conductivity in the cuprates is discussed.Comment: final version of paper (minor changes from previous version

    High prevalence of vitamin D deficiency in Cambodian women:A common deficiency in a sunny country

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    Recent studies have shown that in spite of being generally close to the equator; vitamin D deficiency is common in South East Asian countries. In order to quantify micronutrient status for women and children in Cambodia; a nationally-representative survey was conducted in 2014 linked to the Cambodian Demographic Health Survey. The countrywide median of 25(OH) D was, respectively, 64.9 and 91.1 nmol/L for mothers and children. Based on The Endocrine Society cutoffs (>50<75 nmol/L = insufficiency; <= 50 nmol/L = deficiency); 64.6% of mothers and 34.8% of their children had plasma vitamin D concentrations indicating insufficiency or deficiency. For deficiency alone, 29% of the mothers were found to be vitamin D deficient, but only 13.4% of children. Children who live in urban areas had a 43% higher rate of vitamin D insufficiency versus those who live in rural areas (OR; 1.434; 95% CI: 1.007; 2.041). However, such differences were not observed in their mothers. The high prevalence of vitamin D deficiency is likely in part due to lifestyle choices, including sun avoidance, increasingly predominant indoor work, and covered transport. These survey findings support the need for a broader national Cambodian study incorporating testing of adult men, adolescents and the elderly, and encompassing other parameters such as skeletal health. However, the data presented in this study already show significant deficiencies which need to be addressed and we discuss the benefit of establishing nationally-mandated food fortification programs to enhance the intake of vitamin D
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