Mathematical Methods in Economics and Finance

Rivista internazionale

On the semiclassical treatment of Hawking radiation

In the context of the semiclassical treatment of Hawking radiation we prove the universality of the reduced canonical momentum for the system of a massive shell self gravitating in a spherical gravitational field within the Painlev\'e family of gauges. We show that one can construct modes which are regular on the horizon both by considering as hamiltonian the exterior boundary term and by using as hamiltonian the interior boundary term. The late time expansion is given in both approaches and their time Fourier expansion computed to reproduce the self reaction correction to the Hawking spectrum.Comment: 18 pages, LaTeX, Corrected typo

A note on Hawking radiation via complex path analysis

As long as we neglect backreaction, the Hawking temperature of a given black hole would not depend upon the parameters of the particle species we are considering. In the semiclassical complex path analysis approach of Hawking radiation, this has been verified by taking scalar and Dirac spinors separately for different stationary spacetime metrics. Here we show, in a coordinate independent way that, for an arbitrary spacetime with any number of dimensions, the equations of motion for a Dirac spinor, a vector, spin-$2$ and spin-$\frac{3}{2}$ fields reduce to Klein-Gordon equations in the WKB semiclassical limit. We then obtain, under some suitable assumptions, the complex solutions of those resulting scalar equations across the Killing horizon of a stationary spacetime to get a coordinate independent expression for the emission probability identical for all particle species. Finally we consider some explicit examples to demonstrate the validity of that expression.Comment: 12 pages, v2; manuscript divided into sections, many discussions and references adde

Human Perception of Audio Deepfakes

The recent emergence of deepfakes has brought manipulated and generated content to the forefront of machine learning research. Automatic detection of deepfakes has seen many new machine learning techniques, however, human detection capabilities are far less explored. In this paper, we present results from comparing the abilities of humans and machines for detecting audio deepfakes used to imitate someone's voice. For this, we use a web-based application framework formulated as a game. Participants were asked to distinguish between real and fake audio samples. In our experiment, 472 unique users competed against a state-of-the-art AI deepfake detection algorithm for 14912 total of rounds of the game. We find that humans and deepfake detection algorithms share similar strengths and weaknesses, both struggling to detect certain types of attacks. This is in contrast to the superhuman performance of AI in many application areas such as object detection or face recognition. Concerning human success factors, we find that IT professionals have no advantage over non-professionals but native speakers have an advantage over non-native speakers. Additionally, we find that older participants tend to be more susceptible than younger ones. These insights may be helpful when designing future cybersecurity training for humans as well as developing better detection algorithms.Comment: Published at ACM Multimedia 2022 Workshop DDAM First International Workshop on Deepfake Detection for Audio Multimedia at ACM Multimedia 202

Imaging of biliary involvement in sarcoidosis: Computed tomography, magnetic resonance cholangiopancreatography, and gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid-enhanced magnetic resonance imaging findings

Sarcoidosis is a multisystem disease usually affecting the chest, hilar lymph nodes, and lungs, but can potentially involve any organ; therefore, its clinical presentation may vary. Hepato-biliary involvement is rare, and typically asymptomatic; however, it can lead to cirrhosis, and may require liver transplantation. In this report, we present a rare case of a patient affected by sarcoidosis with hepatobiliary involvement. He presented to our hospital complaining of dyspnea triggered by moderate efforts and oppressive thoracic discomfort. Chest X-ray showed multiple bilateral nodular opacities and enlargement of both hilar regions, confirmed by a subsequent total-body computed tomography scan and positron emission tomography, which also revealed cardiac, splenic, and hepatic involvement. Liver function was studied via gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DTPA)-enhanced magnetic resonance imaging, and magnetic resonance cholangiopancreatography (MRCP) was also performed. The diagnosis of sarcoidosis was finally achieved via liver biopsy, revealing non-necrotizing granulomas in the periportal space. The patient was treated with prednisone per os, with regression of all lesions at all levels. Although other cases of biliary sarcoidosis have been described, this report provides a complete image set of Gd-EOB-DTPA-enhanced magnetic resonance and MRCP images that is lacking in the English literature, and which may be useful for diagnosis

Discrimination in Sentencing on the Basis of Afro-Centric Features

For a long time, social scientists have worried about possible racial discrimination in sentencing in the United States. With a prison population that exceeds two million inmates of whom approximately 48% are African American, the worry over the fairness of the sentencing process is understandable. This article is not about discrimination between racial categories as such, but about a related form of discrimination, namely, discrimination on the basis of a person’s Afro-centric features. Section I of the article describes a line of social science research that shows that a person’s Afro-centric features have a strong biasing effect on judgment such that subjects are more willing to attach racial stereotypes, both positive and negative, to persons whom they perceive as having stronger Afro-centric features. The authors theorize that what is happening is that Afro-centric features have come to have potency to influence judgment on their own, irrespective of race. Section II describes what happened when the authors took their research out of the laboratory and examined the sentencing of inmates in the Florida prison system. The same results were found: when inmates who had committed similar crimes and who had similar criminal histories were compared, inmates who had stronger Afro-centric features received longer sentences within their racial category than inmates with less pronounced Afro-centric features. This result is disturbing because it suggests sentences that are unfair, irrational, and unjust

Permeation of Ternary Mixture Containing H2S, CO2 and CH4 in Aquivion® Perfluorosulfonic Acid (PFSA) Ionomer Membranes

Aquivion (R) E87-12S Perfluorosulfonated acid ionomer material (PFSA) has been studied as a membrane technology for natural gas sweetening from CO2 , H2S due to its interesting chemical and mechanical stability and good separation performance for polar compounds in humid environments. In the present work, permeation of the H2S/CO2/CH4 ternary mixture in this short-side PFSA chain was investigated at pressures up to 10 bar, temperatures up to 50 degrees C, and in a range of relative humidity (RH) from 20% to 90%. The results obtain confirm the strong dependence of Aquivion (R) on water activity and temperature, and its ability to separate gases based on their water solubility without substantial differences between pure and mixed gas experiments. Indeed, even when tested in ternary mixture, the permeation behavior remains similar to that observed for pure components and binary mixtures. In particular, the permeability of H2S is higher than that of CO(2 )and methane CH4, reaching values of 500 Barrer at 50 degrees C and 80% RH, against 450 and 23 Barrer for the other two gases respectively. Additionally, when tested at higher pressures of up to 10 bar under humid conditions, the membrane properties remained largely unchanged, thus confirming the overall stability and durability of Aquivion (R) E87-12S in acid environments

Implementation and cost analysis of a regional farm animal cryobank: an Italian case study

AbstractScientific and technical reports on farm animal genetic resources (AnGR) cryoconservation activities, and related costs, are needed to optimise conservation programmes. In this paper, we presented the recent Italian AnGR gene banking development, including the creation of the first regional animal cryobank, the 'Lombardia Farm Animal Genetic Resources Cryobank' (LABank). In order to provide indications on cryobanking costs, a detailed analysis of the expenses incurred during the creation of LABank was carried out. Currently, in LABank genetic material (spermatozoa, blood and hair bulbs) of Italian cattle, sheep and goat local breeds is cryopreserved, for a total amount of approximately 2500 semen doses collected from 46 donors of five local breeds. The costs incurred by creating the semen storage showed differences among species and semen collection procedures, providing indications to enhance the setting up of regional cryobanks