Market ecology of active and passive investors

We study the role of active and passive investors in an investment market with uncertainties. Active investors concentrate on a single or a few stocks with a given probability of determining the quality of them. Passive investors spread their investment uniformly, resembling buying the market index. In this toy market stocks are introduced as good and bad. If a stock receives sufficient investment it will survive, otherwise die. Active players exert a selective pressure since they can determine to an extent the investment quality. We show that the active players provide the driving force whereas the passive ones act as free riders. While their gains do not differ too much, we show that the active players enjoy an edge. Their presence also provides better gains to the passive players and stocks themselves.Comment: 16 pages, 4 figure

Il Nuovo soggettario in Aleph 500

This document illustrates a project for the adaptation of the ALEPH 500 software to the characteristics of the subject indexing language of "Nuovo soggettario", in respect of the international formats Unimarc/Authorities and Unimarc/Bibliographic. The base unit of the indexing language of "Nuovo soggettario", structured according to the method of GRIS (Gruppo di ricerca sull'indicizzazione per soggetto, Research Group on Subject Indexing), is the indexing term, either representing a concept or referring to an individually-named entity, in the form of a noun or noun phrase. The indexing terms are not coincident to the elements of the traditional subject headings, the so-called "descrittori" in SBN (the Italian National library service)

Efficacy of Operculectomy in the Treatment of 145 Cases with Unerupted Second Molars: A Retrospective Case–Control Study

The aim of this study is to assess whether operculectomy in patients with retained second molars eases spontaneous tooth eruption in respect to untreated controls. Two hundred and twenty-two patients with delayed eruption of at least one second molar were selected from the archives of the Department of Orthodontics, Milan, Italy. Eighty-eight patients, 40 males and 48 females (mean age 14.8 ± 1.3 years), met the inclusion criteria. Records were then divided into case and control groups. The case group consisted of patients that underwent removal of the overlaying mucosa over second molars (i.e., operculectomy) and the control group consisted of subjects who retained their operculum over an unerupted second molar and were followed for one year without performing any treatment. A total of 145 impacted second molars were considered (75 cases, 70 controls). A risk ratio with 95% confidence interval was used to compare the prevalence of eruption in the two groups. Spontaneous eruption occurred in 93.3% of cases in the operculectomy group (70/75), while in the control group, 10% teeth erupted spontaneously (7/70). Spontaneous eruption in the upper arch occurred in 95.2% of cases among treated patients (40 out of 42), while in the lower arch, spontaneous eruption occurred in 90.9% of cases (30 out of 33). Spontaneous eruption of the upper second molars in the control group occurred in 8.5% of cases (3 out of 35), while in the lower arch, it occurred in 8.5% (3 out of 35). Operculectomy can ease the spontaneous eruption of retained second molars and reduce the chances of inclusion

Il Nuovo soggettario in Aleph 500

This document illustrates a project for the adaptation of the ALEPH 500 software to the characteristics of the subject indexing language of "Nuovo soggettario", in respect of the international formats Unimarc/Authorities and Unimarc/Bibliographic. The base unit of the indexing language of "Nuovo soggettario", structured according to the method of GRIS (Gruppo di ricerca sull'indicizzazione per soggetto, Research Group on Subject Indexing), is the indexing term, either representing a concept or referring to an individually-named entity, in the form of a noun or noun phrase. The indexing terms are not coincident to the elements of the traditional subject headings, the so-called "descrittori" in SBN (the Italian National library service)

I titoli uniformi negli archivi di autorità di sistemi UNIMARC in colloquio con Indice, con particolare riferimento ad ALEPH 500

The Italian cataloguing code (Regole italiane di catalogazione, REICAT) requires the identification of all the works represented in the catalogue by the use of uniform titles. In the SBN-MARC protocol of the Italian National Library Service network (SBN), the authority records for the uniform titles have a different structure from the one proposed by the UNIMARC Authorities format: this prevents the respect of the cataloguing rules, the correct indexing of works and expressions and consequently their effective retrieval and display in the OPACs. This paper illustrates the problems and the possible solutions, both in the SBN-MARC protocol and in the UNIMARC systems that are hubs linked to SBN Index system, the core of the collective catalogue

Phase and amplitude electroencephalography correlations change with disease progression in people with idiopathic rapid eye-movement sleep behavior disorder

Study Objectives Increased phase synchronization in electroencephalography (EEG) bands might reflect the activation of compensatory mechanisms of cognitive decline in people with neurodegenerative diseases. Here, we investigated whether altered large-scale couplings of brain oscillations could be linked to the balancing of cognitive decline in a longitudinal cohort of people with idiopathic rapid eye-movement sleep behavior disorder (iRBD). Methods We analyzed 18 patients (17 males, 69.7 +/- 7.5 years) with iRBD undergoing high-density EEG (HD-EEG), presynaptic dopaminergic imaging, and clinical and neuropsychological (NPS) assessments at two time points (time interval 24.2 +/- 5.9 months). We thus quantified the HD-EEG power distribution, orthogonalized amplitude correlation, and weighted phase-lag index at both time points and correlated them with clinical, NPS, and imaging data. Results Four patients phenoconverted at follow-up (three cases of parkinsonism and one of dementia). At the group level, NPS scores decreased over time, without reaching statistical significance. However, alpha phase synchronization increased and delta amplitude correlations decreased significantly at follow-up compared to baseline. Both large-scale network connectivity metrics were significantly correlated with NPS scores but not with sleep quality indices or presynaptic dopaminergic imaging data. Conclusions These results suggest that increased alpha phase synchronization and reduced delta amplitude correlation may be considered electrophysiological signs of an active compensatory mechanism of cognitive impairment in people with iRBD. Large-scale functional modifications may be helpful biomarkers in the characterization of prodromal stages of alpha-synucleinopathies.Peer reviewe

La qualità della formazione medica nel distance learning

This study arises from the desire of investigate the perceived effectiveness and critical issues of distance learning, which has been adopted by universities during the SARS-CoV-2 pandemic. An anonymous survey was distributed among Italian medical students, trying to reach the largest part of them via the communication channels of SISM – Segretariato Italiano Studenti in Medicina – APS. 1,489 students from 40 universities have filled in the survey. 75% of the sample attended distance lectures, whereas 11% took part to Problem or Case Based Learning activities. Most of the reported criticism was due to organizational or logistic issues rather than technological ones. Half of the sample has not perceived any variations relating to the interaction with the teachers, whereas most of the interviewed people perceives a decreased interaction with classmates as an affectingly factor on their learning. 48% of the sample reports a greater distractibility and 38% a greater tiredness in comparison with face-to-face teaching. The essential lesson methods to set up an effective distance learning (e.g. e-learning) were probed through collected data and scientific literature. The main outcome has been acknowledging that the roles of the learner and the teacher in the process of distance learning differ from the equivalent roles in face-to-face learning. Therefore, redefining lesson methods and broadly curricular contents is required in order to organize an effective distance learning.Il presente studio nasce dalla volontà di rispondere a quesiti inerenti all’efficacia percepita e alle criticità del distance learning adottato dagli atenei italiani in risposta alla pandemia SARS-CoV-2. È stata distribuita una survey anonima agli studenti di Medicina e Chirurgia, cercando di raggiungerne un campione il più rappresentativo possibile tramite i canali di comunicazione del SISM - Segretariato Italiano Studenti in Medicina - APS. La survey è stata compilata da 1.489 persone afferenti a 40 atenei differenti. Il 75% del campione ha partecipato a lezioni frontali a distanza, mentre solo l’11% ha preso parte ad attività di Problem o Case Based Learning. La maggior parte dei problemi riscontrati dagli studenti è stata di natura organizzativa e logistica più che tecnologica. La metà del campione non ha rilevato variazioni nell’interazione con il docente, mentre la maggior parte percepisce una diminuzione nell'interazione con i compagni. Il 48% del campione accusa una maggiore distraibilità e il 38% una maggiore stanchezza. Tramite le fonti e i dati raccolti sono state indagate le metodiche imprescindibili per l’organizzazione di un distance learning efficace, come l’e-learning, nel quale le figure dei docenti e dei discenti assumono nuovi ruoli, con l’acquisizione di una maggiore autonomia da parte dei secondi. In conclusione, affinché il distance learning possa essere efficace è necessaria – in particolare in un contesto di Medical Education – una ridefinizione delle modalità di lezione e, più in generale, del contenuto dei curricula italiani

Functional cortical source connectivity of resting state electroencephalographic alpha rhythms shows similar abnormalities in patients with mild cognitive impairment due to Alzheimer's and Parkinson's diseases

Objective: This study tested the hypothesis that markers of functional cortical source connectivity of resting state eyes-closed electroencephalographic (rsEEG) rhythms may be abnormal in subjects with mild cognitive impairment due to Alzheimer's (ADMCI) and Parkinson's (PDMCI) diseases compared to healthy elderly subjects (Nold). Methods: rsEEG data had been collected in ADMCI, PDMCI, and Nold subjects (N = 75 for any group). eLORETA freeware estimated functional lagged linear connectivity (LLC) from rsEEG cortical sources. Area under receiver operating characteristic (AUROC) curve indexed the accuracy in the classification of Nold and MCI individuals. Results: Posterior interhemispheric and widespread intrahemispheric alpha LLC solutions were abnormally lower in both MCI groups compared to the Nold group. At the individual level, AUROC curves of LLC solutions in posterior alpha sources exhibited moderate accuracies (0.70-0.72) in the discrimination of Nold vs. ADMCI-PDMCI individuals. No differences in the LLC solutions were found between the two MCI groups. Conclusions: These findings unveil similar abnormalities in functional cortical connectivity estimated in widespread alpha sources in ADMCI and PDMCI. This was true at both group and individual levels. Significance: The similar abnormality of alpha source connectivity in ADMCI and PDMCI subjects might reflect common cholinergic impairment. (C) 2018 International Federation of Clinical Neurophysiology. Published by Elsevier B.V. All rights reserved