General Bounds on Electronic Shot Noise in the Absence of Currents

We investigate the charge and heat electronic noise in a generic two-terminal mesoscopic conductor in the absence of the corresponding charge and heat currents. Despite these currents being zero, shot noise is generated in the system. We show that, irrespective of the conductor’s details and the specific nonequilibrium conditions, the charge shot noise never exceeds its thermal counterpart, thus establishing a general bound. Such a bound does not exist in the case of heat noise, which reveals a fundamental difference between charge and heat transport under zero-current conditions

Charge, spin, and heat shot noises in the absence of average currents: Conditions on bounds at zero and finite frequencies

Nonequilibrium situations where selected currents are suppressed are of interest in fields like thermoelectrics and spintronics, raising the question of how the related noises behave. We study such zero-current charge, spin, and heat noises in a two-terminal mesoscopic conductor. In the presence of voltage, spin, and temperature biases, the nonequilibrium (shot) noises of charge, spin, and heat can be arbitrarily large, even if their average currents vanish. However, as soon as a temperature bias is present, additional equilibrium (thermal-like) noise necessarily occurs. We show that this equilibrium noise sets an upper bound on the zero-current charge and spin shot noises, even if additional voltage or spin biases are present. We demonstrate that these bounds can be overcome for heat transport by breaking the spin and electron-hole symmetries, respectively. By contrast, we show that the bound on the charge noise for strictly two-terminal conductors even extends into the finite-frequency regime

Constraints between entropy production and its fluctuations in nonthermal engines

We analyze a mesoscopic conductor autonomously performing a thermodynamically useful task, such as cooling or producing electrical power, in a part of the system - the working substance - by exploiting another terminal or set of terminals - the resource - that contains a stationary nonthermal (nonequilibrium) distribution. Thanks to the nonthermal properties of the resource, on average no exchange of particles or energy with the working substance is required to fulfill the task. This resembles the action of a demon, as long as only average quantities are considered. Here, we go beyond a description based on average currents and investigate the role of fluctuations in such a system. We show that a minimum level of entropy fluctuations in the system is necessary, whenever one is exploiting a certain entropy production in the resource terminal to perform a useful task in the working substance. For concrete implementations of the demonic nonthermal engine in three- and four-terminal electronic conductors in the quantum Hall regime, we compare the resource fluctuations to the entropy production in the resource and to the useful engine output (produced power or cooling power)

SCC: A Service Centered Calculus

We seek for a small set of primitives that might serve as a basis for formalising and programming service oriented applications over global computers. As an outcome of this study we introduce here SCC, a process calculus that features explicit notions of service definition, service invocation and session handling. Our proposal has been influenced by Orc, a programming model for structured orchestration of services, but the SCC’s session handling mechanism allows for the definition of structured interaction protocols, more complex than the basic request-response provided by Orc. We present syntax and operational semantics of SCC and a number of simple but nontrivial programming examples that demonstrate flexibility of the chosen set of primitives. A few encodings are also provided to relate our proposal with existing ones

New Synthetic Analogues of Natural Polyphenols as Sirtuin 1-Activating Compounds

NAD+-dependent deacetylase SIRT1 regulates many different biological processes, thus being involved in pathogenic conditions such as metabolic diseases, neurogenerative disorders and cancer. Notably, experimental evidence underlined that the activation of SIRT1 had promising cardioprotective effects. Consequently, many efforts have been so far devoted to finding new SIRT1 activators, both derived from natural sources or prepared by synthetic procedures. Herein, we discovered new SIRT1-activating derivatives, characterized by phenolic rings spaced by sulfur, nitrogen or oxygen-based central linkers. The newly synthesized derivatives were analyzed in enzymatic assays to determine their ability to activate SIRT1, as compared with that of resveratrol. Among the tested molecules, bisarylaniline compound 10 proved to be the most efficient SIRT1 activator. An evaluation of the effects caused by focused structural variations revealed that its para-hydroxy-substituted diphenyl moiety of 10 was the fundamental structural requirement for achieving good SIRT1 activation. Compound 10 was further investigated in ex vivo studies in isolated and perfused rat hearts submitted to ischemia/reperfusion (I/R), where it showed significant protection of the myocardium against I/R injury. Molecular modeling studies suggest the binding mode of 10 within SIRT1 in the presence of the p53-AMC peptide. Our findings reveal that this chemical scaffold may be used as the starting point to develop a new class of more potent SIRT1 activators as cardioprotective agents

efficacy and safety of amtolmetin guacyl in the symptomatic treatment of the osteoarthritis

Forty-two patients affected by osteoarthritis have been treated with two parallel schemes, in double blind, according to parallel groups, to have a correct evaluation of the efficacy and safety of Amtolmetin Guacyl administration on at full stomach or empty stomach. As parameters of efficacy the spontaneus pain and the pain caused by movements, the function and joint pain have been considered, while gastric tolerance has been evaluated by means of daily records made by patients and the general tolerance through an annotation of adverse events, vital signs as well as parameters of laboratory. The drug worked for both groups, but it has been particulary efficent in those who have assumed the drug on a empty stomach. The general tolerance has been good and some adverse side effects, concerning the gastric tolerance, have disappeared by reducing the dosage of the drug. As a result of this study we can assume that amtolmetin guacyl is much more efficent when it is assumed on a empty stomach, with its conseguent advantages in terms of compliance and its possible utilization in case of need

Tisa: A Language Design and Modular Verification Technique for Temporal Policies in Web Services

Web services are distributed software components, that are decoupled from each other using interfaces with specified functional behaviors. However, such behavioral specifications are insufficient to demonstrate compliance with certain temporal non-functional policies. An example is demonstrating that a patient’s health-related query sent to a health care service is answered only by a doctor (and not by a secretary). Demonstrating compliance with such policies is important for satisfying governmental privacy regulations. It is often necessary to expose the internals of the web service implementation for demonstrating such compliance, which may compromise modularity. In this work, we provide a language design that enables such demonstrations, while hiding majority of the service’s source code. The key idea is to use greybox specifications to allow service providers to selectively hide and expose parts of their implementation. The overall problem of showing compliance is then reduced to two subproblems: whether the desired properties are satisfied by the service’s greybox specification, and whether this greybox specification is satisfied by the service’s implementation. We specify policies using LTL and solve the first problem by model checking. We solve the second problem by refinement techniques

Towards a formal account for software transactional memory

International audienceSoftware transactional memory (STM) is a concurrency control mechanism for shared memory systems. It is opposite to the lock based mechanism, as it allows multiple processes to access the same set of variables in a concurrent way. Then according to the used policy, the effect of accessing to shared variables can be committed (hence, made permanent) or undone. In this paper, we define a formal framework for describing STMs and show how with a minor variation of the rules it is possible to model two common policies for STM: reader preference and writer preference