Gravity from the entropy of light

The holographic principle, considered in a semiclassical setting, is shown to have direct consequences on physics at a fundamental level. In particular, a certain relation is pointed out to be the expression of holography in basic thermodynamics. It is argued moreover that through this relation holography can be recognized to induce gravity, and an expression for the gravitational lensing is obtained in terms of entropy over wavelength of black-body radiation, or, at a deeper level, in terms of maximum entropy over associated space to the elementary bit of information.Comment: 7 pages; v2: completion of the list of references; v3: the discussion is divided in Sections and the argument is described in more detail; v4: a statement is added (below eq.13) on what is the supposed difference between Jacobson's work in ref.21 and this attempt; addition of a paragraph in last Sectio

How did italian adolescents with disability and parents deal with the covid-19 emergency?

The COVID-19 emergency has imposed distanced education and has interrupted most rehabilitation services. Adolescents with disabilities have been isolated, and the burden on their families has been exacerbated. A cross-sectional survey was administered to adolescents with disability and to parents of disabled children to describe their experience during lockdown and their concerns or expectations about rehabilitation. A sample of 53 adolescents and 239 parents completed the survey. Adolescents were ages 13\u201318 years old (45.3% female). Most parents were between 35 and 55 years old (84.9% female). While 53.6% of the parents reported no positive effects of the lockdown, 92.5% of the adolescents expressed favorable consequences. The increased time spent with family members was judged positively by 27.2% of parents and by 64.2% of adolescents. Concern for their child\u2019s disability was expressed by 47.3% of parents, while 73.6% of adolescents expressed concerns regarding the ban on meeting friends. In both groups, anxiety symptoms were correlated with the fear of contracting COVID-19 and with financial problems. Parents would have liked even more remote support from school and healthcare professionals, which was available for most participants. Thus, socioeconomic support, assistive technology and telerehabilitation strategies might help families with disabilities during a lockdown

Relative entropy and the Bekenstein bound

Elaborating on a previous work by Marolf et al, we relate some exact results in quantum field theory and statistical mechanics to the Bekenstein universal bound on entropy. Specifically, we consider the relative entropy between the vacuum and another state, both reduced to a local region. We propose that, with the adequate interpretation, the positivity of the relative entropy in this case constitutes a well defined statement of the bound in flat space. We show that this version arises naturally from the original derivation of the bound from the generalized second law when quantum effects are taken into account. In this formulation the bound holds automatically, and in particular it does not suffer from the proliferation of the species problem. The results suggest that while the bound is relevant at the classical level, it does not introduce new physical constraints semiclassically.Comment: 12 pages, 1 figure, minor changes and references adde

Reproductive aspects of the velvet belly lantern shark Etmopterus spinax (Condrichthyes: Etmopteridae), from the central western Mediterranean sea. Notes on gametogenesis and oviducal gland microstructure.

In this paper, the reproductive biology of the velvet belly lanternshark Etmopterus spinax was analyzed in Sardinian waters (central western Mediterranean). This species was sexually dimorphic with females growing to a larger size than males. Marked sexual dimorphism in size was also observed along the vertical gradient. Histological analysis of gonads was very useful in assigning macroscopical maturity stages. The investigation on the microstructure of oviducal gland (OG) highlighted four morphofunctional zones with mucous and/or proteic secretions according to the zone and to their specific functions and development. Sperm in the OG was found for the first time in E. spinax. The localization of sperm storage tubules deeper in OG suggested long-term sperm storage, which is in agreement with the long reproductive cycle described. This species matured late, specifically at 80.7% and 79% at the maximum observed size for females and males respectively. Mature specimens were found throughout the year with pregnant females observed in winter and autumn. A low fecundity was observed with a mean ovarian fecundity of 16.5 mature follicles

LA SUBSIDENZA NELL’ITALIA CENTRO-SETTENTRIONALE DA MISURE GPS

La grande diffusione negli ultimi anni di reti di stazioni GPS permanenti istituite per scopi commerciali come il posizionamento in tempo reale, può rappresentare un’importante integrazione alla già esistente rete scientifica di monitoraggio della deformazione crostale. Le stazioni commerciali sono solitamente equipaggiate con ricevitori a doppia frequenza e antenne tipo choke ring. Una possibile differenza fra queste e le stazioni scientifiche consiste nell’approccio utilizzato per la scelta del sito e per la monumentazione. Per questo motivo prima di utilizzare le osservazioni acquisite dalle stazioni commerciali per analisi di tipo scientifico bisogna verificare se i protocolli di installazione e gestione di questi non introducano nuove sorgenti di rumore nei dati o aumentino quelle già esistenti. In questo studio, abbiamo confrontato le caratteristiche principali delle serie temporali di 112 stazioni commerciali situate nell’Italia Centro–Settentrionale con quelle di 81 stazioni scientifiche presenti nella medesima zona (Fig. 1). Le osservazioni delle 112 stazioni commerciali prese in esame sono fornite dalle seguenti agenzie pubbliche e private: ASSOGEO, LABTOPO, Rete Regione Veneto, SOGER, IREALP, Rete Arpa Piemonte e Regione Abruzzo; e i dati delle 81 stazioni scientifiche sono stati invece acquisiti dagli archivi informatici di 5 diverse istituzioni pubbliche: ASI, INGV – RING, EUREF, FREDNET e Rete Toscana. Le osservazioni di tutte le stazioni considerate in questo lavoro sono state analizzate mediante il software GAMIT/GLOBK versione 10.34 e successive utilizzando la procedura denominata distributed processing (Dong et alii, 1998), che consente di analizzare reti con un alto numero di stazioni suddividendole in diverse sottoreti distinte, compensando successivamente i risultati ottenuti in un’unica soluz

Geodetic deformation Across the Central Apennines from GPS Data in the time span 1999-2003

Abstract During the time span 1999-2003 was set up and repeatedly surveyed a not permanent GPS network located across one of the highest seismic areas of the central Apennines (Italy). The Central Apennine Geodetic Network (CA-GeoNet), extends across Umbria, Abruzzo, Marche and Lazio regions, in an area of ∼180x130 km, from Tyrrhenian to the Adriatic sea. It consists in 125 GPS stations distributed at 3-5 km average grid and includes 7 permanent GPS stations operated by the Italian Space Agency (ASI) and the Istituto Nazionale di Geofisica and Vulcanologia (INGV). With the aim to estimate the active strain rate across this part of the chain, the GPS sites have been located on the main geological units of the area and across the typical basin and range structures, related with the main seismogenic faults. In this paper we show the network and the first results obtained for a subset of 23 stations that have been occupied at least during three repeated campaigns, in the time span 1999-2003. Data analysis, performed by Bernese 4.2 software, shows an extensional rate normal to the chain, in agreement with geological and seismic data. The strain rates in the inner chain are ranging from 12x10-9±11yr-1 to 16x10-9±11yr-1 and from -14x10-9±11yr-1 to -3x10-9±11yr-1. This result provides an improved estimation of the ongoing deformation of this area with respect to previous studies and is in agreement with the style of deformation inferred from seismicity and with the features of the main seismogenic sources from recent geological and seismological investigations

APPROCCIO MULTI-DISCIPLINARE AL PROBLEMA DELLA SUBSIDENZA NELLA REGIONE EMILIA ROMAGNA

L’estrazione di fluidi sotterranei ha prodotto significativi fenomeni di subsidenza nel territorio della Regione Emilia-Romagna. Al fine di analizzare il fenomeno, per meglio comprenderne l’origine e gli aspetti evolutivi, è stato utilizzato un approccio multidisciplinare basato su innovativi sistemi di controllo delle quote piezometriche dei pozzi e degli spostamenti della superficie topografica. In particolare mediante la tecnica di interferometria DInSAR – SBAS sono state elaborate 52 immagini distribuite su un’area compresa tra l’Appennino bolognese e il fiume Po. E’ stata inoltre studiata l’evoluzione temporale delle quote piezometriche dei pozzi presenti in Regione, con lo scopo di evidenziare aree potenzialmente soggette a subsidenza confrontabile con i dati di spostamento al suolo DInSAR e con dati geodetici (livellazioni e dati GPS). Un significativo miglioramento della conoscenza dei fenomeni di subsidenza potrà avvenire integrando i risultati ottenuti con i dati forniti dalla nuova rete di stazioni GPS permanenti progettata congiuntamente dall’INGV e dall’Università di Bologna. L’analisi di dati geologici, idrogeologici, telerilevati e geodetici ha portato a risultati significativi per una corretta comprensione dei processi di subsidenza su buona parte della città di Bologna e della sua provincia. Tale approccio verrà esteso a tutta l’area compresa tra la catena appenninica ed il fiume Po

DISTRIBUTION OF SPAWNING AND NURSERY GROUNDS FOR DEEP–WATER RED SHRIMPS IN THE CENTRAL WESTERN MEDITERRANEAN SEA

The presence of spawning and nursery grounds of Aristeids in the central western Mediterranean Sea were investigated using fishery-independent data (trawl surveys, 1994–2012). Spatial distributions were generated for mature animals and recruits, for both spring/summer and autumn data, using an inverse distance weighted deterministic interpolation. The persistence index was used to identify stable spawning and nursery grounds in the Sardinian slope region for Aristaeomorpha foliacea and Aristeus antennatus. Areas of aggregation for recruits and mature females appear connected with important physical habitat features. The analysis also suggests a seasonal bathymetric distribution for nursery areas. The recruits of A. foliacea are located in the upper part of the continental slope (377-450 m) in spring-summer and reach greater depths (468-628 m) in autumn. For A. antennatus, for which nursery areas only emerge in autumn, there is presumably an opposite ontogenic migration, from deep sea to upper slope, during the summer (575-681 m). Results indicate also a partial overlap between the nursery and spawning grounds of both species. In this particular areas, local environmental conditions such as upwelling events or the presence of canyons and seamounts seem to play an important role in their distribution. This study generated also relevant information on the spatial and temporal distribution of seasonal or persistent aggregations of spawners and recruits, providing scientific elements to suggest the feasibility of protecting these important resources

Digital elevation models for landslide evolution monitoring: application on two areas located in the Reno River Valley (Italy)

GPS, digital photogrammetry and laser scanning techniques have been applied and compared in the frame of the studies of two complex landslides located in the Emilia-Romagna Region (Northern Italy). The three approaches, characterized by different accuracies, applicability and costs, have demonstrated to be efficient tools to define Digital Elevation Models computed in the same reference system and able to provide data on the landslide motion. The results described in the paper indicate the present low level of landslide activity in recent years. Reliability, costs and execution times of the applied surveying methods are shown and discussed in this paper

A taxonomic survey of female oviducal glands in chondrichthyes: A comparative overview of microanatomy in the two reproductive modes

Oviducal glands (OGs) are distinct expanded regions of the anterior portion of the oviduct, commonly found in chondrichthyans, which play a key role in the production of the egg in-vestments and in the female sperm storage (FSS). The FSS phenomenon has implications for understanding the reproductive ecology and management of exploited populations, but little information is available on its taxonomic extent. For the first time, mature OGs from three lecithotrophic oviparous and four yolk-sac viviparous species, all considered at risk from the fishing impacts in the central western Mediterranean Sea, were examined using light microscopy. The OG microanatomy, whose morphology is generally conserved in all species, shows differences within the two reproductive modalities. Oviparous species show a more developed baffle zone in respect to viviparous ones because of the production of different egg envelopes produced. Among oviparous species, Raja polystigma and Chimaera monstrosa show presence of sperm, but not sperm storage as observed, instead, in Galeus melastomus and in all the viviparous sharks, which preserve sperm inside of specialized structures in the terminal zone