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

Influence of projectile shape on dynamic behavior of steel sheet subjected to impact and perforation

Authors thank Ministry of Science and Higher Education of Poland for financial support under Grants: R00 0097 12. Authors thank also M. Tavian technician in electronics from ENIM for his contribution on the development of the residual velocity measurement sensors.The paper describes a work focused on the process of perforation of steel sheet.Experimental,analytical and numerical investigations have been carried out to analyze in details the perforation process.Based on these approaches,the ballistic properties of the material and the failure modes depending on the projectile nose shape(conical,blunt or hemispherical) have been studied.Different failure modes have been observed,including petaling, plug ejection and circumference necking.The special study about the number of petals has been done for different nose angles using conical shape projectiles.The complete energy balance is also reported and the absorbed energy by the steel sheet has been obtained by measuring initial and residual projectile velocities.A wide range of impact velocities from 35to180m/s has been covered during the tests.All the projectiles are 13mm in diameter and the plates are1mm thick.Moreover,the mass ratio(projectile mass/steel sheet mass) and the ratio between the span of the steel sheet and the diameter of the projectile are constant, equal to 0.38 and 3.85, respectively

Metal oxide semiconductors employed as photocatalysts during water splitting

Photocatalytic water splitting has attracted significant interest in recent decades as it offers a clean and environmentally friendly route for the production of hydrogen. A key challenge remains the development of systems that employ abundant, non-toxic and inexpensive materials to dissociate water efficiently using sunlight. Titanium dioxide (TiO2), tungsten trioxide (WO3) and hematite (α-Fe2O3) are among the most studied photoanodes employed during water splitting because of the position of their valence band which is suitable for oxidising water to oxygen, and their low costs. However reported efficiencies for these materials are below the reported theoretical maximum values. A good understanding of the factors that are limiting the efficiency of these photoanodes is therefore desirable if improvements in the photocatalytic activity are to be achieved. This thesis is divided in four main sections. Chapters 3 and 4 describe transient absorption spectroscopy (TAS) studies in the microsecond-second timescales carried out on WO3 photoelectrodes and TiO2 nanowires respectively. TAS has been employed to follow the charge carriers dynamics in WO3 highlighting the presence of relatively long-lived holes (30 ms), which have been described as a requirement for the water oxidation reaction to take place. The electrons also appear to be long-lived (0.1 s), and this has been proposed to be due to slow electron transport through the film. TAS measurements have also been carried out on oxygen-deficient hydrogen-treated TiO2 nanowires, highlighting a more efficient suppression of the electron/hole recombination process in comparison with conventional anatase TiO2 photoanodes. Chapter 5 describes TAS and sum frequency generation (SFG) studies on TiO2 films which are designed to investigate the surface mechanisms of water oxidation. The dependence of the hole lifetime on the pH of the electrolytes employed has been examined by TAS and substantially faster decay rates have been found in highly alkaline solutions suggesting a change in the mechanism of water oxidation. Consequently, SFG has been employed in order to detect any possible intermediate at the interface TiO2/water. Initial measurements have provided the evidence of physisorbed and chemisorbed methanol (model probe) on the TiO2 surface and further studies at the TiO2/water interface have been carried out. Chapter 6 describes the development of a hybrid solar fuel reactor coupling a α-Fe2O3 based photoelecrochemical cell with luminescent solar concentrator plates. Initial tests have been carried out on a proof of principle prototype providing encouraging results.Open Acces

Dye diffusion during laparoscopic tubal patency tests may suggest a lymphatic contribution to dissemination in endometriosis: A prospective, observational study

Aim Women with adenomyosis are at higher risk of endometriosis recurrence after surgery. This study was to assess if the lymphatic vessel network drained from the uterus to near organs where endometriosis foci lied. Methods A prospective, observational study, Canadian Task Force Classification II-2, was conducted at Sacro Cuore Don Calabria Hospital, Negrar, Italy. 104 white women aged 18–43 years were enrolled consecutively for this study. All patients underwent laparoscopy for endometriosis and a tubal dye test was carried out. Results Evidence of dye dissemination through the uterine wall and outside the uterus was noted in 27 patients (26%) with adenomyosis as it permeated the uterine wall and a clear passage of the dye was shown in the pelvic lymphatic vessels regardless whether the tubes were unobstructed. Histological assessment of the uterine biopsies confirmed adenomyosis. Conclusion Adenomyosis is characterized by ectatic lymphatics that allow the drainage of intrauterine fluids (the dye and, perhaps, menstrual blood) at minimal intrauterine pressure from the uterine cavity though the lymphatic network to extrauterine organs. Certainly, this may not be the only explanation for endometriosis dissemination but the correlation between the routes of the dye drainage and location of endometriosis foci is highly suggestive

Automated DEM extraction in digital aerial photogrammetry: precisions and validation for mass movement monitoring

Automated procedures for photogrammetric image processing and Digital Elevation Models (DEM) extraction yield high precision terrain models in a short time, reducing manual editing; their accuracy is strictly related to image quality and terrain features. After an analysis of the performance of the Digital Photogrammetric Workstation (DPW) 770 Helava, the paper compares DEMs derived from different surveys and registered in the same reference system. In the case of stable area, the distribution of height residuals, their mean and standard deviation values, indicate that the theoretical accuracy is achievable automatically when terrain is characterized by regular morphology. Steep slopes, corrugated surfaces, vegetation and shadows can degrade results even if manual editing procedures are applied. The comparison of multi-temporal DEMs on unstable areas allows the monitoring of surface deformation and morphological changes

Dramatically different levels of cacna1a gene expression between pre-weaning wild type and leaner mice

Loss of function mutations of the CACNA1A gene, coding for the α1A subunit of P/Q type voltage-gated calcium channel (Ca(V)2.1), are responsible for Episodic Ataxia type 2 (EA2), an autosomal dominant disorder. A dominant negative effect of the EA2 mutated protein, rather than a haploinsufficiency mechanism, has been hypothesised both for protein-truncating and missense mutations. We analysed the cacna1a mRNA expression in leaner mice carrying a cacna1a mutation leading to a premature stop codon. The results showed a very low mutant mRNA expression compared to the wild type allele. Although the mutant mRNA slightly increases with age, its low level is likely due to degradation by nonsense mediated decay, a quality control mechanism that selectively degrades mRNA harbouring premature stop codons. These data have implications for EA2 in humans, suggesting a haploinsufficiency mechanism at least for some of the CACNA1A mutations leading to a premature stop codon

Remote Sensing and Geodetic Measurements for Volcanic Slope Monitoring: Surface Variations Measured at Northern Flank of La Fossa Cone (Vulcano Island, Italy)

Abstract: Results of recent monitoring activities on potentially unstable areas of the NW volcano flank of La Fossa cone (Vulcano Island, Italy) are shown here. They are obtained by integration of data by aerial photogrammetry, terrestrial laser scanning (TLS) and GPS taken in the 1996–2011 time span. A comparison between multi-temporal models built from remote sensing data (photogrammetry and TLS) highlights areas characterized by ~7–10 cm/y positive differences (i.e., elevation increase) in the upper crown of the slope. The GPS measurements confirm these results. Areas characterized by negative differences, related to both mass collapses or small surface lowering, also exist. The higher differences, positive and negative, are always observed in zones affected by higher fumarolic activity. In the 2010–2012 time span, ground motions in the northern part of the crater rim, immediately above the upper part of observed area, are also observed. The results show different trends for both vertical and horizontal displacements of points distributed along the rim, with a magnitude of some centimeters, thus revealing a complex kinematics. A slope stability analysis shows that the safety factors estimated from these data do not OPEN ACCESS Remote Sens. 2013, 5 2239 indicate evidence of possible imminent failures. Nevertheless, new time series are needed to detect possible changes with the time of the stability conditions, and the monitoring has to go on

Antiphase Synchronization in a Flagellar-Dominance Mutant of Chlamydomonas

This is the final version. Available on open access from American Physical Society via the DOI in this record. Groups of beating flagella or cilia often synchronize so that neighboring filaments have identical frequencies and phases. A prime example is provided by the unicellular biflagellate Chlamydomonas reinhardtii, which typically displays synchronous in-phase beating in a low-Reynolds number version of breaststroke swimming. We report the discovery that ptx1, a flagellar-dominance mutant of C. reinhardtii, can exhibit synchronization in precise antiphase, as in the freestyle swimming stroke. High-speed imaging shows that ptx1 flagella switch stochastically between in-phase and antiphase states, and that the latter has a distinct waveform and significantly higher frequency, both of which are strikingly similar to those found during phase slips that stochastically interrupt in-phase beating of the wild-type. Possible mechanisms underlying these observations are discussed.Spanish Ministerio de Ciencia y InnovaciónEngineering and Physical Sciences Research Council (EPSRC)Biotechnology and Biological Sciences Research Council (BBSRC)European Research CouncilWellcome Trus

A proof of the Bekenstein bound for any strength of gravity through holography

The universal entropy bound of Bekenstein is considered, at any strength of the gravitational interaction. A proof of it is given, provided the considered general-relativistic spacetimes allow for a meaningful and inequivocal definition of the quantities which partecipate to the bound (such as system's energy and radius). This is done assuming as starting point that, for assigned statistical-mechanical local conditions, a lower-limiting scale l* to system's size definitely exists, being it required by holography through its semiclassical formulation as given by the generalized covariant entropy bound. An attempt is made also to draw some possible general consequences of the l* assumption with regards to the proliferation of species problem and to the viscosity to entropy density ratio. Concerning the latter, various fluids are considered including systems potentially relevant, to some extent, to the quark-gluon plasma case.Comment: 13 pages. v2: the title is modified; the discussion is strengthened and made more concise (10pp). v3: some short clarifications adde

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