1,467 research outputs found

    Branes and fluxes in special holonomy manifolds and cascading field theories

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    We conduct a study of holographic RG flows whose UV is a theory in 2+1 dimensions decoupled from gravity, and the IR is the N=6,8 superconformal fixed point of ABJM. The solutions we consider are constructed by warping the M-theory background whose eight spatial dimensions are manifolds of special holonomies sp(1) times sp(1) and spin(7). Our main example for the spin(7) holonomy manifold is the A8 geometry originally constructed by Cvetic, Gibbons, Lu, and Pope. On the gravity side, our constructions generalize the earlier construction of RG flow where the UV was N=3 Yang-Mills-Chern-Simons matter system and are simpler in a number of ways. Through careful consideration of Page, Maxwell, and brane charges, we identify the discrete and continuous parameters characterizing each system. We then determine the range of the discrete data, corresponding to the flux/rank for which the supersymmetry is unbroken, and estimate the dynamical supersymmetry breaking scale as a function of these data. We then point out the similarity between the physics of supersymmetry breaking between our system and the system considered by Maldacena and Nastase. We also describe the condition for unbroken supersymmetry on class of construction based on a different class of spin(7) manifolds known as B8 spaces whose IR is different from that of ABJM and exhibit some interesting features.Comment: 51 pages, 12 figures. Update in quantization of G4 on B8 in equations (5.12) and (5.13

    Experimental modulation of capsule size in Cryptococcus neoformans

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    Experimental modulation of capsule size is an important technique for the study of the virulence of the encapsulated pathogen Cryptococcus neoformans. In this paper, we summarize the techniques available for experimental modulation of capsule size in this yeast and describe improved methods to induce capsule size changes. The response of the yeast to the various stimuli is highly dependent on the cryptococcal strain. A high CO(2) atmosphere and a low iron concentration have been used classically to increase capsule size. Unfortunately, these stimuli are not reliable for inducing capsular enlargement in all strains. Recently we have identified new and simpler conditions for inducing capsule enlargement that consistently elicited this effect. Specifically, we noted that mammalian serum or diluted Sabouraud broth in MOPS buffer pH 7.3 efficiently induced capsule growth. Media that slowed the growth rate of the yeast correlated with an increase in capsule size. Finally, we summarize the most commonly used media that induce capsule growth in C. neoformans

    Neoadjuvant endocrine therapy in primary breast cancer: indications and use as a research tool

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    Neoadjuvant endocrine therapy has been increasingly employed in clinical practice to improve surgical options for postmenopausal women with bulky hormone receptor-positive breast cancer. Recent studies indicate that tumour response in this setting may predict long-term outcome of patients on adjuvant endocrine therapy, which argues for its broader application in treating hormone receptor-positive disease. From the research perspective, neoadjuvant endocrine therapy provides a unique opportunity for studies of endocrine responsiveness and the development of novel therapeutic agents

    Histopathologist Features Predictive of Diagnostic Concordance at Expert Level Amongst a Large International Sample of Pathologists Diagnosing Barrett’s Dysplasia Using Digital Pathology

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    Objective Guidelines mandate expert pathology review of Barrett’s oesophagus (BO) biopsies that reveal dysplasia, but there are no evidence-based standards to corroborate expert reviewer status. We investigated BO concordance rates and pathologist features predictive of diagnostic discordance. Design Pathologists (n=51) from over 20 countries assessed 55 digitised BO biopsies from across the diagnostic spectrum, before and after viewing matched p53 labelling. Extensive demographic and clinical experience data were obtained via online questionnaire. Reference diagnoses were obtained from a review panel (n=4) of experienced Barrett’s pathologists. Results We recorded over 6000 case diagnoses with matched demographic data. Of 2805H&E diagnoses, we found excellent concordance (>70%) for nondysplastic BO and high-grade dysplasia, and intermediate concordance for low-grade dysplasia (42%) and indefinite for dysplasia (23%). Major diagnostic errors were found in 248 diagnoses (8.8%), which reduced to 232 (8.3%) after viewing p53 labelled slides. Demographic variables correlating with diagnostic proficiency were analysed in multivariate analysis, which revealed that at least 5 years of professional experience was protective against major diagnostic error for H&E slide review (OR 0.48, 95% CI 0.31 to 0.74). Working in a non-teaching hospital was associated with increased odds of major diagnostic error (OR 1.76, 95% CI 1.15 to 2.69); however, this was neutralised when pathologists viewed p53 labelled slides. Notably, neither case volume nor self-identifying as an expert predicted diagnostic proficiency. Extrapolating our data to real-world case prevalence suggests that 92.3% of major diagnostic errors are due to overinterpreting non-dysplastic BO. Conclusion Our data provide evidence-based criteria for diagnostic proficiency in Barrett’s histopathology

    Summing Up All Genus Free Energy of ABJM Matrix Model

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    The localization technique allows us to compute the free energy of the U(N)_k x U(N)_{-k} Chern-Simons-matter theory dual to type IIA strings on AdS_4 x CP^3 from weak to strong 't Hooft coupling \lambda = N / k at finite N, as demonstrated by Drukker, Marino, and Putrov. In this note we study further the free energy at large 't Hooft coupling with the aim of testing AdS/CFT at the quantum gravity level and, in particular, sum up all the 1/N corrections, apart from the worldsheet instanton contributions. The all genus partition function takes a remarkably simple form -- the Airy function, Ai (k^{4/3} \lambda_r), with the renormalized 't Hooft coupling \lambda_r.Comment: 18 pages, no figures, v2: typos corrected and references adde

    Phase II study of gemcitabine and vindesine in patients with previously untreated non-resectable non-small-cell lung cancer

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    Because both vindesine and gemcitabine are active drugs in advanced non-small-cell lung cancer (NSCLC), with different modes of action and only partly overlapping toxicity, a phase II study was performed. Gemcitabine 1000 mg m−2 was given on days 1, 8 and 15 every 4 weeks, while vindesine 3 mg m−2 was administered weekly for 7 weeks, then every 2 weeks. A total of 42 patients with nonresectable NSCLC were included. The median age of patients was 56 years; 57% were men, 52% had adenocarcinoma, 31% squamous cell carcinoma and 17% had large-cell carcinoma. The performance status ranged from 0 to 2 with 83% in performance status 1. The majority (55%) had stage IV disease, while 40% had stage III B and 5% stage III A disease. WHO grade 3–4 leucopenia occurred in five patients (12%) and 9% had grade 4 neutropenia. Thrombocytopenia grade 3–4 was observed in six patients (15%). There were no septic death or bleeding episodes. One patient had a transient WHO grade 4 increase in bilirubin, and four patients had a decrease in glomerular filtration rate below the normal limit; one of these patients developed a non-reversible renal insufficiency. Ten patients (24%) complained of dyspnoea of uncertain mechanism, possibly involving bronchoconstriction. There were one complete and seven partial responses among 40 assessable patients (20%, 95% confidence limits 9–36%). Median response duration was 31 weeks (range 11–83 weeks) and median survival time 31 weeks (range 2–171 weeks). The current combination of gemcitabine and vindesine does not appear to be promising for further examination because of the toxicity and somewhat disappointing activity. © 1999 Cancer Research Campaig

    The particle number in Galilean holography

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    Recently, gravity duals for certain Galilean-invariant conformal field theories have been constructed. In this paper, we point out that the spectrum of the particle number operator in the examples found so far is not a necessary consequence of the existence of a gravity dual. We record some progress towards more realistic spectra. In particular, we construct bulk systems with asymptotic Schrodinger symmetry and only one extra dimension. In examples, we find solutions which describe these Schrodinger-symmetric systems at finite density. A lift to M-theory is used to resolve a curvature singularity. As a happy byproduct of this analysis, we realize a state which could be called a holographic Mott insulator.Comment: 29 pages, 1 rudimentary figure; v2: typo in eqn (3.4), added comments and ref

    Channel choice complications:Exploring the multiplex nature of citizens' channel choices

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    Part 2: E-Government Services and Open GovernmentInternational audienceIn spite of massive investment and increased adoption of digital services, citizens continue to use traditional channels to interact with public organizations. The channel choice (CC) field of research tries to understand citizens’ interactions with public authorities to make the interaction more efficient and increase citizen satisfaction. However, most studies have been conducted either as surveys of hypothetical services or in experimental settings, leading to a lack of empirical data from actual use contexts. Therefore, we present the results of a sequential mixed methods study which combines observations of citizen-caseworker interaction in a call center, contextual interviews with callers, and a survey classifying topics from 10,000 telephone calls. We contribute to the CC field and practice with rich empirical data from studies of actual channel choices. Specifically, the study explores the multiplex nature of real-life CC and demonstrate how telephone calls can be part of a process, which occurs across both traditional and digital channels. Moreover, we identify problems, which cause telephone calls related to digital services, and classify these in two groups: information related problems and action related problems
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