1,026 research outputs found
OPE Convergence in Conformal Field Theory
We clarify questions related to the convergence of the OPE and conformal
block decomposition in unitary Conformal Field Theories (for any number of
spacetime dimensions). In particular, we explain why these expansions are
convergent in a finite region. We also show that the convergence is
exponentially fast, in the sense that the operators of dimension above Delta
contribute to correlation functions at most exp(-a Delta). Here the constant
a>0 depends on the positions of operator insertions and we compute it
explicitly.Comment: 26 pages, 6 figures; v2: a clarifying note and two refs added; v3:
note added concerning an extra constant factor in the main error estimate,
misprint correcte
D3-D7 Quark-Gluon Plasmas at Finite Baryon Density
We present the string dual to SU(Nc) N=4 SYM, coupled to Nf massless
fundamental flavors, at finite temperature and baryon density. The solution is
determined by two dimensionless parameters, both depending on the 't Hooft
coupling at the scale set by the temperature T:
, weighting the backreaction of the flavor
fields and , where is the
baryon density. For small values of these two parameters the solution is given
analytically up to second order. We study the thermodynamics of the system in
the canonical and grand-canonical ensembles. We then analyze the energy loss of
partons moving through the plasma, computing the jet quenching parameter and
studying its dependence on the baryon density. Finally, we analyze certain
"optical" properties of the plasma. The whole setup is generalized to non
abelian strongly coupled plasmas engineered on D3-D7 systems with D3-branes
placed at the tip of a generic singular Calabi-Yau cone. In all the cases,
fundamental matter fields are introduced by means of homogeneously smeared
D7-branes and the flavor symmetry group is thus a product of abelian factors.Comment: 27 pages; v2: 29 pages, 1 (new) figure, new section 4.4 on optical
properties, references, comments added; v3: eq. (3.19), comments and a
reference adde
Effects of sex and menstrual cycle phase on cardiac response and alpha- amylase levels in psychosocial stress
The impact of sex and the menstrual cycle phase on the autonomic response to psychosocial stress remains controversial. This study explored autonomic nervous system activity through salivary alpha-amylase, heart rate, and heart rate variability responses to the Trier Social Stress Test (TSST) in healthy young people. The sample was composed of 25 men, 26 women in the luteal phase, and 25 women in the follicular phase, from 18 to 25 years of age. Participants were exposed to the TSST or a control condition. The results indicate that women in their follicular phase showed a blunted alpha-amylase response to stress compared to men and women in the luteal phase. In addition, men showed higher sympatho-vagal activity in the stress condition compared to the two groups of women. These results confirm that sex and the menstrual cycle phase are potential modulators of autonomic nervous system reactivity to psychosocial stress
European Respiratory Society guidelines for the management of adult bronchiectasis
Bronchiectasis in adults is a chronic disorder associated with poor quality of life and frequent exacerbations in many patients. There have been no previous international guidelines.The European Respiratory Society guidelines for the management of adult bronchiectasis describe the appropriate investigation and treatment strategies determined by a systematic review of the literature.A multidisciplinary group representing respiratory medicine, microbiology, physiotherapy, thoracic surgery, primary care, methodology and patients considered the most relevant clinical questions (for both clinicians and patients) related to management of bronchiectasis. Nine key clinical questions were generated and a systematic review was conducted to identify published systematic reviews, randomised clinical trials and observational studies that answered these questions. We used the GRADE approach to define the quality of the evidence and the level of recommendations. The resulting guideline addresses the investigation of underlying causes of bronchiectasis, treatment of exacerbations, pathogen eradication, long term antibiotic treatment, anti-inflammatories, mucoactive drugs, bronchodilators, surgical treatment and respiratory physiotherapy.These recommendations can be used to benchmark quality of care for people with bronchiectasis across Europe and to improve outcomes
Holographic Duals of Quark Gluon Plasmas with Unquenched Flavors
We review the construction of gravitational solutions holographically dual to
N=1 quiver gauge theories with dynamical flavor multiplets. We focus on the
D3-D7 construction and consider the finite temperature, finite quark chemical
potential case where there is a charged black hole in the dual solution.
Discussed physical outputs of the model include its thermodynamics (with
susceptibilities) and general hydrodynamic properties.Comment: Lecture presented at the Workshop "AdS/CFT and Novel Approaches to
Hadron and Heavy Ion Physics", Kavli Institute of Theoretical Physics
(KITPC), Beijing, China, 13 October 2010. Review article to be published in
Communications in Theoretical Physics. 27 pages, 2 figure
Crosstalk between glial and glioblastoma cells triggers the "go-or-grow" phenotype of tumor cells
Background: Glioblastoma (GBM), the most malignant primary brain tumor, leads to poor and unpredictable clinical outcomes. Recent studies showed the tumor microenvironment has a critical role in regulating tumor growth by establishing a complex network of interactions with tumor cells. In this context, we investigated how GBM cells modulate resident glial cells, particularly their paracrine activity, and how this modulation can influence back on the malignant phenotype of GBM cells.
Methods: Conditioned media (CM) of primary mouse glial cultures unexposed (unprimed) or exposed (primed) to the secretome of GL261 GBM cells were analyzed by proteomic analysis. Additionally, these CM were used in GBM cells to evaluate their impact in glioma cell viability, migration capacity and activation of tumor-related intracellular pathways.
Results: The proteomic analysis revealed that the pre-exposure of glial cells to CM from GBM cells led to the upregulation of several proteins related to inflammatory response, cell adhesion and extracellular structure organization within the secretome of primed glial cells. At the functional levels, CM derived from unprimed glial cells favored an increase in GBM cell migration capacity, while CM from primed glial cells promoted cells viability. These effects on GBM cells were accompanied by activation of particular intracellular cancer-related pathways, mainly the MAPK/ERK pathway, which is a known regulator of cell proliferation.
Conclusions: Together, our results suggest that glial cells can impact on the pathophysiology of GBM tumors, and that the secretome of GBM cells is able to modulate the secretome of neighboring glial cells, in a way that regulates the "go-or-grow" phenotypic switch of GBM cells.Fundação para a Ciência e Tecnologia (IF/00601/2012 to B.M.C.; IF/00111 to A.J.S; SFRH/BD/52287/2013 to A.I.O.; SFRH/BD/81495/2011 to S.I.A.; SFRH/BD/88121/2012 to J.V.C.; projects PTDC/SAU-GMG/113795/2009 to B.M.C.; PTDC/NEU-NMC/0205/2012, PTDC/NEU-SCC/7051/2014, PEst-C/SAU/LA0001/2013–2014 and UID/NEU/04539/2013 to B.M.), Liga Portuguesa Contra o Cancro (B.M.C.), Fundação Calouste Gulbenkian (B.M.C.) and Inter-University Doctoral Programme in Ageing and Chronic Disease (PhDOC; to A.I.O.). Project co-financed by Programa Operacional Regional do Norte (ON.2—O Novo Norte), Quadro de Referência Estratégico Nacional (QREN), Fundo Europeu de Desenvolvimento Regional (FEDER), Programa Operacional Factores de Competitividade (COMPETE), and by The National Mass Spectrometry Network (RNEM) under the contract REDE/1506/REM/2005info:eu-repo/semantics/publishedVersio
CBM language measures as indicators of foreign-language learning: technical adequacy of scores for secondary-school students
Education and Child Studie
Control possibilities for community microgrids considering small production processes and its benefits to the whole system
The use of nonrandomized evidence to estimate treatment effects in health technology assessment
Health technology assessment (HTA) is increasingly informed by non-randomised studies but there is limited guidance from HTA bodies on expectations around evidence quality and study conduct. We developed recommendations to support the appropriate use of such evidence based on a pragmatic literature review and a workshop involving 16 experts from 8 countries as part of the European Union’s Horizon-2020 IMPACT-HTA programme (work package 6). To ensure HTA processes remain rigorous and robust, HTA bodies should demand clear, extensive, and structured reporting of non-randomised studies, including an in-depth assessment of the risk of bias. In recognition of the additional uncertainty imparted by non-randomised designs in estimates of treatment effects, HTA bodies should strengthen early scientific advice and engage in collaborative efforts to improve use of real-world data
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