Fault Awareness in the MPI 4.0 Session Model

The latest version of MPI introduces new functionalities like the Session model, but it still lacks fault management mechanisms. Past efforts produced tools and MPI standard extensions to manage fault presence, including ULFM. These measures are effective against faults but do not fully support the new additions to the standard. In this paper, we combine the fault management possibilities of ULFM with the new Session model functionality introduced in version 4.0 of the standard. We focus on the communicator creation procedure, highlighting criticalities and proposing a method to circumvent them. The experimental campaign shows that the proposed solution does not significantly affect applications' execution time and scalability while better managing the insurgence of faults

N=2 gauge theories from the ODE-IM correspondence perspective

Nel presente elaborato di tesi, D. Gregori ha sviluppato un metodo ricorsivo molto efficiente, per calcolare gli integrali del moto locali delle teorie conformi quantistiche. Tale calcolo è stato svolto nel contesto della corrispondenza ODE/IM, tra certe equazioni di Schrödinger e i modelli integrabili conformi. A tal fine, è stato sfruttato il semplice comportamento ricorsivo dei cosiddetti polinomi di Gelfand-Dikii, grazie anche a una precedente dimostrazione di D. Fioravanti, concernente l’espansione asintotica, per grande energia, della funzione d’onda. Inoltre, D. Gregori, ha adattato tale dimostrazione alla cosiddetta espansione WKB (nota anche come approssimazione WKB), cioè per piccola constante di Planck, ottenendo così una ricorsione efficiente anche per questo noto metodo di soluzione delle equazioni di Schrödinger con singolarità. Questo nuovo approccio all’approssimazione WKB ha permesso di dimostrare una congettura di W. He a Y. Miao, nel contesto delle teorie di gauge con N = 2 supersimmetrie (SUSY). Inoltre, nel presente elaborato, è stato parzialmente completato un lavoro, molto incompleto e pubblicato postumo, di Al. B. Zamolodchikov, riguardo alla costruzione della corrispondenza ODE/IM per il modello di Liouville, ovvero per carica centrale c ≥ 25. L’equazione della ODE/IM da utilizzare, in questo caso, è l’equazione di Mathieu Generalizzata, così battezzata da Al. B. Zamolodchikov. Per il caso c = 25 "autoduale", tale equazione si riduce all’equazione di Mathieu e questo permette una diretta connessione con le teorie di gauge N = 2 SUSY. In questo caso autoduale, D. Gregori ha dimostrato una congettura di Al. B. Zamolodchikov, secondo cui la funzione T di Baxter delle teorie integrabili coincide con il coseno dell’indice di Floquet dell’equazione di Mathieu; dove quest’ultimo è proporzionale alla deformazione quantistica (nel limite di Nekrasov-Shatashvili) del ciclo classico di Seiberg-Witten, delle teorie di gauge con N = 2 SUSY

Mental Imagery Cracked: Direct Monitoring of the Continuous Movements of Covert Visuospatial Attention During Motion Imagery

We sought to provide direct evidence of the attention movements during dynamic mental imagery. Observers extrapolated in imagery the horizontal motion of a target with the gaze in central fixation. We recorded the steady-statevisual- evoked potentials (SSVEP) generated by flickering the left and right sides of the screen at two different frequencies. We found a consistent SSVEP modulation as a function of the imagined target position. Concurrent finger pointing, but not mental training, increased the SSVEP modulation. We conclude that the electrophysiological signature of covert visuospatial attention can be used to reveal non-invasively the continuous spatio-temporal dynamics of mental imagery

Annuario Registro dati 2005

No abstract availabl

Handling missing continuous outcome data in a Bayesian network meta-analysis

Background: A Bayesian network meta-analysis (NMA) model is a statistical method aimed at estimating the relative effects of multiple interventions against the same disease. The method has recently gained prominence, leading to the synthesis of the evidence regarding rank probabilities for each treatment. In several cases, an NMA is performed excluding incomplete data of studies retrieved through a systematic review, resulting in a loss of precision and power.  Methods: There are several methods for handling missing or incomplete data in an NMA framework, especially for continuous outcomes. In certain cases, only baseline and follow-up measurements are available; in this framework, to obtain data regarding mean changes, it is necessary to consider the pre-post study correlation. In this context, in a Bayesian setting, several authors suggest imputation strategies for pre-post correlation. In other cases, a variability measure associated with a mean change score might be unavailable. Different imputation methods have been suggested, such as those based on maximum standard deviation imputation. The purpose of this study is to verify the robustness of Bayesian NMA models concerning different imputation strategies through simulations.  Results: Simulation results show that the bias is notably small for every scenario, confirming that rankings provided by models are robust concerning different imputation methods in several heterogeneity-correlation settings.  Conclusions: This NMA method seems to be more robust to missing data imputation when data reported in different studies are generated in a low-heterogeneity scenario. The NMA method seems to be more robust to missing value imputation if the expectation of the prior distribution, defined on the heterogeneity parameter, approaches the true value of the variability across studies.&nbsp

A survey on Biostatisticians Serving in the Italian Ethics Committees

Background. Italian ethics committees (ECs) have the responsibility for evaluating and monitoring clinical research. Methods. An electronic survey targeted to the biostatisticians operating in the 95 ECs in Italy, was launched in November 2016. Several aspects were explored such as education, job title, training in biostatistics and experience in the evaluation of protocols within the EC. Results. Seventy case report forms were returned (74%), and the response rate was highest for ECs located in the South (78%) and lowest in the North (51%). The biostatisticians in the respondent ECs were prevalently male, aged 50-60 years, with postgraduate education in medical specialties and statistics. The annual workload varied depending on the type of institution and geographical area, with an annual median number of protocols examined ranging from 80 in hospital ECs to 198 in university hospital ECs, and from 80 to 108, in the South and the Centre, respectively. Of these, 40% were observational study protocols. The EC biostatisticians proposed to reject 5% of protocols and to suspend with the request of clarification or amendments 10%. Only 61% and 79% of these opinions, respectively, were regarded as binding by the other EC members. Conclusion. The biostatistician will not be able to play a significant role in the EC as long as the required skill-set remains vague and his/her opinion on a protocol is underrated

Collecting Use Cases Information: Method and Template for Physical Science for the OpenPOWER Foundation

The main purpose of this Note is to define a method and a template to collect Physical Science use cases from scientists and research engineers working on Physical Science projects in the context and within the scope of the OpenPOWER Foundation for Physical Science Workgroup. An effective method (shared between all stakeholders) could contribute to • understand the workflow, starting with user expectations; • help Physical Science projects maintain costs within a chosen envelope; • map the functionalities to the scientific requirements; • remove possible misunderstanding between the scientific community and ICT stakeholders