253 research outputs found
From Minimal Strings towards Jackiw-Teitelboim Gravity: On their Resurgence, Resonance, and Black Holes
Two remarkable facts about JT two-dimensional dilaton-gravity have been
recently uncovered: this theory is dual to an ensemble of quantum mechanical
theories; and such ensemble is described by a random matrix model which itself
may be regarded as a special (large matter-central-charge) limit of minimal
string theory. This work addresses this limit, putting it in its broader
matrix-model context; comparing results between multicritical models and
minimal strings (i.e., changing in-between multicritical and conformal
backgrounds); and in both cases making the limit of large matter-central-charge
precise (as such limit can also be defined for the multicritical series). These
analyses are first done via spectral geometry, at both perturbative and
nonperturbative levels, addressing the resurgent large-order growth of
perturbation theory, alongside a calculation of nonperturbative
instanton-actions and corresponding Stokes data. This calculation requires an
algorithm to reach large-order, which is valid for arbitrary two-dimensional
topological gravity. String equations -- as derived from the GD construction of
the resolvent -- are analyzed in both multicritical and minimal string
theoretic contexts, and studied both perturbatively and nonperturbatively
(always matching against the earlier spectral-geometry computations). The
resulting solutions, as described by resurgent transseries, are shown to be
resonant. The large matter-central-charge limit is addressed -- in the
string-equation context -- and, in particular, the string equation for JT
gravity is obtained to next derivative-orders, beyond the known genus-zero case
(its possible exact-form is also discussed). Finally, a discussion of
gravitational perturbations to Schwarzschild-like black hole solutions in these
minimal-string models, regarded as deformations of JT gravity, is included -
alongside a brief discussion of quasinormal modes.Comment: 107 pages, 50 plots in 25 figures, 2 tables, jheppub-nosort.sty; v2:
minor corrections/typo
Resurgent large genus asymptotics of intersection numbers
In this paper, we present a novel approach for computing the large genus
asymptotics of intersection numbers. Our strategy is based on a resurgent
analysis of the -point functions of such intersection numbers, which are
computed via determinantal formulae, and relies on the presence of a quantum
curve. With this approach, we are able to extend the recent results of Aggarwal
for Witten-Kontsevich intersection numbers with the computation of all
subleading corrections, proving a conjecture of Guo-Yang, and to obtain new
results on -spin and Theta-class intersection numbers.Comment: 47 pages, 7 figure
Resurgent Asymptotics of Jackiw-Teitelboim Gravity and the Nonperturbative Topological Recursion
Jackiw-Teitelboim dilaton-quantum-gravity localizes on a double-scaled
random-matrix model, whose perturbative free energy is an asymptotic series.
Understanding the resurgent properties of this asymptotic series, including its
completion into a full transseries, requires understanding the nonperturbative
instanton sectors of the matrix model for Jackiw-Teitelboim gravity. The
present work addresses this question by setting-up instanton calculus
associated to eigenvalue tunneling (or ZZ-brane contributions), directly in the
matrix model. In order to systematize such calculations, a nonperturbative
extension of the topological recursion formalism is required -- which is herein
both constructed and applied to the present problem. Large-order tests of the
perturbative genus expansion validate the resurgent nature of Jackiw-Teitelboim
gravity, both for its free energy and for its (multi-resolvent) correlation
functions. Both ZZ and FZZT nonperturbative effects are required by resurgence,
and they further display resonance upon the Borel plane. Finally, the
resurgence properties of the multi-resolvent correlation functions yield new
and improved resurgence formulae for the large-genus growth of Weil-Petersson
volumes.Comment: 63 pages, 52 plots in 16 figures, jheppub-nosort.sty; v2: minor
corrections/typo
Assessment of Glucose Lowering Medications’ Effectiveness for Cardiovascular Clinical Risk Management of Real-World Patients with Type 2 Diabetes: Targeted Maximum Likelihood Estimation under Model Misspecification and Missing Outcomes
Personal values in mental disorders: an exploratory analysis
AbstractPersonal values have increasingly become central in socio-psychological research. However, the relationships between values and psychopathological variables have been scarcely investigated, with mixed results. This study aimed to explore potential differences in value orientation in a sample of people with psychotic disorders and mood disorders compared to a non-clinical sample using the Schwarz's values framework. A clinical sample of 162 subjects (92 subjects with psychotic disorders and 70 with mood disorders) and a non-clinical sample of 217 subjects completed the self-report measures of affective states (PANAS) and personal values (PVQ). Irrespective of the diagnostic group, the clinical sample showed higher expression of Conservation values (i.e., Tradition, Conformity, Security). Conservation and Self-enhancement values positively correlated with PANAS-positive affectivity in the clinical sample; in the non-clinical sample, Self-enhancement values only correlated with PANAS-positive affectivity. The expression of Conservation values in individuals with a mental disorder could reflect an orientation toward Conformity underlying fundamental affiliative goals. The complex relationship between personal values and clinical constructs should be further investigated, with important theoretical and clinical implications in mental health
Simulations of distributed systems in a computing centre
Modern computing centres addressed to High Energy Physics user communities have to deal with rapidly hard- ware and software systems evolution. These centres normally face a variety of problems associated with the dimensioning and configuration of several services which must satisfy per- formance targets under different usage patterns. Therefore, the identification of key variables and the estimation of their impact on services performances is challenging. For example, given an hardware-software configuration for a considered service, how will service performance vary in relation to user dependent settings? Will it be able to support a certain number of requests per minute over the common parameter ranges? In addition, it is difficult to generalize the impact of same settings over different usage scenarios. Therefore, the design of a mathematical model able to relate services performance to key variables in the user computing patterns under common hardware-software settings can help to optimize the exploitation of computing resources. In the present work, starting from the analysis of a typical job of ATLAS as representative HEP user communities, we focus on how local data movement operations use hardware- software resources of INFN-CNAF computing centre and which variables affect data movement performances. As a result of this framework analysis we identify GridFTP protocol and GPFS data storage as core services whose performance to study in depen- dancy of typical user defined variables. We therefore decompose data movement commands in operations of increasing complexity i.e., cp, globus-url-copy with and without network, and after defining the mean throughput per file per unit size as target metric, we conduct a quantitative analysis of the contribution and relevance of considered variables across explored usage scenarios. Finally, we conduct a qualitative fit analysis of the behaviour of chosen throughput metric as a function of relevant user dependent variables. For each scenario and for each variables a best fit model function is selected according to R-square goodness of fit index
Extended criteria donor lung reconditioning with the organ care system lung: a single institution experience
Lung transplantation is a life-saving procedure limited by donor's availability. Lung reconditioning by ex vivo lung perfusion represents a tool to expand the donor pool. In this study, we describe our experience with the OCS\u2122 Lung to assess and recondition extended criteria lungs. From January 2014 to October 2016, of 86 on-site donors evaluated, eight lungs have been identified as potentially treatable with OCS\u2122 Lung. We analyzed data from these donors and the recipient outcomes after transplantation. All donor lungs improved during OCS perfusion in particular regarding the PaO2/FiO2 ratio (from 340 mmHg in donor to 537 mmHg in OCS) leading to lung transplantation in all cases. Concerning postoperative results, primary graft dysfunction score 3 at 72 h was observed in one patient, while median mechanical ventilation time, ICU, and hospital stay were 60 h, 14 and 36 days respectively. One in-hospital death was recorded (12.5%), while other two patients died during follow-up leading to 1-year survival of 62.5%. The remaining five patients are alive and in good conditions. This case series demonstrates the feasibility and value of lung reconditioning with the OCS\u2122 Lung; a prospective trial is underway to validate its role to safely increase the number of donor lungs. \ua9 2018 Steunstichting ESO
New professions for academic research libraries
La sezione "Note e discussioni" di questo numero di AIB studi offre una prima riflessione sui profili professionali emergenti nella biblioteca accademica di ricerca. I quattro contributi di Sada, Sirito e Gregori, Morando, Minsenti e Gargiulo – preceduti da una nota introduttiva di Maria Cassella sul nuovo ruolo della biblioteca accademica di ricerca – esplorano alcuni di questi profili professionali a partire dagli interventi presentati in occasione di un seminario di studio organizzato a Roma nel novembre 2012.Ellis Sada, Liliana Gregori e Paolo Sirito affermano la necessità che gli operatori di biblioteca a tutti i livelli non si limitino più soltanto a un ruolo passivo nel ciclo della conoscenza (selezione, acquisizione e distribuzione dei contenuti) ma diventino parte attiva del ciclo stesso. Maddalena Morando analizza la figura del repository manager, il cui compito consiste nella pianificazione e gestione dell'Institutional Repository (IR) come vetrina della produzione scientifica di ateneo, e cerca di calare le buone pratiche internazionali nella realtà universitaria italiana. Pierfranco Minsenti ci parla invece del coordinatore dei servizi informativi online (o responsabile della gestione di un portale). Il portale, inteso non come semplice piattaforma tecnologica ma come servizio, presuppone infatti una nuova e più stretta integrazione tra attività di back-office (gestione dei sistemi, creazione di metadati, gestione delle risorse elettroniche ecc.) e di front-office (fornitura di documenti, assistenza nell’accesso alle risorse elettroniche). Per finire, Paola Gargiulo delinea le competenze umane e professionali richieste all'electronic resources librarian, il bibliotecario addetto all'acquisizione, gestione, manutenzione, organizzazione e accesso delle risorse informative elettroniche.The Note e discussioni's section of the journal's current issue focuses on the new professional profiles for academic research libraries. All the papers included in this section were presented during a workshop held in Rome in November 2012, and are introduced by a preliminary note by Maria Cassella on the new role of academic research library.Ellis Sada, Liliana Gregori and Paolo Sirito claim the necessity, for information professional, to be no longer passively engaged in the cycle of knowledge (e.g. by the mere selection, acquisition and distribution of content) but to became an active part of the very same cycle too. Maddalena Morando analyses the repository manager's professional profile, whose job is the planning and management of the Institutional Repository (IR) as a showcase of the university's scientific production. She also tries to imagine which good practices could be adapted from the existing literature to the context of Italian universities. Pierfranco Minsenti gives an effective account of what a coordinator of online information services (i.e. the person in charge of the web-based library portal) does: the management of a library portal – not just a technological platform, but an actual service – requires improved synergies among back-office activities (such as systems management, metadata creation, electronic resources management) and front-office activities (such as document delivery and assistance in accessing electronic resources). Finally, Paola Gargiulo describes the core competencies and abilities of the electronic resources librarian, who covers all the activities related to the acquisition, licensing, management of ER
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