Sudden death and sudden birth of entanglement in common structured reservoirs

We study the exact entanglement dynamics of two qubits in a common structured reservoir. We demonstrate that, for certain classes of entangled states, entanglement sudden death occurs, while for certain initially factorized states, entanglement sudden birth takes place. The backaction of the non-Markovian reservoir is responsible for revivals of entanglement after sudden death has occurred, and also for periods of disentanglement following entanglement sudden birth.Comment: 4 pages, 2 figure

An Extensive Questionnaire about Metacognition during Emergency Remote Teaching Involving More Than 3000 Engineering Students

By 11 March 2020, the phrase “COVID-19” had officially entered everyday life across most of the word. Each level of education suddenly faced new changes and new challenges. Emergency remote teaching became widespread, and new methodologies to deliver classes and courses were adopted by educational institutions. In this paper, we focus on the impact of the remote learning experience of engineering students enrolled at the Politecnico di Milano. The subjects were recruited from all engineering courses from the first to the fifth year and were asked to complete a multidimensional survey. The survey featured 66 items regarding the participants’ perceptions of the challenges of emergency remote teaching compared with pre-COVID-19 in-person teaching. The questionnaire addressed six dimensions: the organization of emergency remote teaching, subjective well-being, metacognition, self-efficacy, identity, and socio-demographic information. In this paper, we describe the entire survey and discuss a preliminary analysis. Using Cronbach’s alpha test, a confirmatory factor analysis, and the t-test, we performed a more in-depth analysis concerning the outcomes of metacognition and self-efficacy. The data analysis suggested a small, unexpected change in the metacognition strategies. The students, in some regards, improved their learning strategies. Some other answers underlined their appreciation of the courses’ organization and the lack of relationships with their peers and teachers

Phenomenological memory-kernel master equations and time-dependent Markovian processes

Do phenomenological master equations with memory kernel always describe a non-Markovian quantum dynamics characterized by reverse flow of information? Is the integration over the past states of the system an unmistakable signature of non-Markovianity? We show by a counterexample that this is not always the case. We consider two commonly used phenomenological integro-differential master equations describing the dynamics of a spin 1/2 in a thermal bath. By using a recently introduced measure to quantify non-Markovianity [H.-P. Breuer, E.-M. Laine, and J. Piilo, Phys. Rev. Lett. 103, 210401 (2009)] we demonstrate that as far as the equations retain their physical sense, the key feature of non-Markovian behavior does not appear in the considered memory kernel master equations. Namely, there is no reverse flow of information from the environment to the open system. Therefore, the assumption that the integration over a memory kernel always leads to a non-Markovian dynamics turns out to be vulnerable to phenomenological approximations. Instead, the considered phenomenological equations are able to describe time-dependent and uni-directional information flow from the system to the reservoir associated to time-dependent Markovian processes.Comment: 5 pages, no figure

Funnel plots and choropleth maps in cancer risk communication: a comparison of tools for disseminating population-based incidence data to stakeholders

Background: Population-based cancer registries provide epidemiological cancer information, but the indicators are often too complex to be interpreted by local authorities and communities, due to numeracy and literacy limitations. The aim of this paper is to compare the commonly used visual formats to funnel plots to enable local public health authorities and communities to access valid and understandable cancer incidence data obtained at the municipal level. Methods: A funnel plot representation of standardised incidence ratio (SIR) was generated for the 82 municipalities of the Palermo Province with the 2003 2011 data from the Palermo Province Cancer Registry (Sicily, Italy). The properties of the funnel plot and choropleth map methodologies were compared within the context of disseminating epidemiological data to stakeholders. Results: The SIRs of all the municipalities remained within the control limits, except for Palermo city area (SIR=1.12), which was sited outside the upper control limit line of 99.8%. The Palermo Province SIRs funnel plot representation was congruent with the choropleth map generated from the same data, but the former resulted more informative as shown by the comparisons of the weaknesses and strengths of the 2 visual formats. Conclusions: Funnel plot should be used as a complementary valuable tool to communicate epidemiological data of cancer registries to communities and local authorities, visually conveying an efficient and simple way to interpret cancer incidence data

Critical assessment of two-qubit post-Markovian master equations

A post-Markovian master equation has been recently proposed as a tool to describe the evolution of a system coupled to a memory-keeping environment [A. Shabani and D. A. Lidar, Phys. Rev. A 71, 020101 (R) (2005)]. For a single qubit affected by appropriately chosen environmental conditions, the corresponding dynamics is always legitimate and physical. Here we extend such situation to the case of two qubits, only one of which experiences the environmental effects. We show how, despite the innocence of such an extension, the introduction of the second qubit should be done cum grano salis to avoid consequences such as the breaking of the positivity of the associated dynamical map. This hints at the necessity of using care when adopting phenomenologically derived models for evolutions occurring outside the Markovian framework.Comment: 7 pages, 1 figure, RevTeX4. Close to published versio

Factors associated with dog behavioral problems referred to a behavior clinic

Undesirable behaviors are common in the domestic dog population. This study aimed to identify similarities and differences in characteristics underlying 2 major groups of behavioral problems, and their treatment outcome. The study focused on 335 dogs that visited a Behavioral Clinic in northern Italy between 2013 and 2016. These cases were categorized into 2 broad groups based on the diagnosis: an \u201caggressive\u201d group (behavioral pathologies involving aggression) and an \u201canxious\u201d group (behavioral pathologies not primarily involving aggression). Each dog underwent a behavior consultation made by a veterinary specialist who used a basic history questionnaire focused on all aspects of dog's behavior, management, and health issue. Several variables were selected from the questionnaires collected. We found a statistical association of the behavioral problem with factors such as size, sex, age, time of onset, dogs' resting place, family composition, and mounting behaviors involving people (P 64 0.05). Small- and medium-sized dogs were mainly \u201canxious\u201d instead of \u201caggressive\u201d; male dogs were mostly \u201caggressive\u201d and female dogs (neutered and intact) were mainly \u201canxious\u201d; dogs adopted from pet shops were all anxious. On average, \u201caggressive\u201d dogs exhibited the problem 4 months after adoption. \u201cAnxious\u201d dogs exhibited the problem within 1 week of adoption. The resting place and diagnosis were statistically related (P 64 0.05): the 20% of dogs that slept on owners' bed were mainly \u201canxious\u201d dogs (78% of these). Sixty-five percent of \u201canxious\u201d dogs and 33% of \u201caggressive\u201d dogs showed mounting behaviors toward people. Most (72.3%) (N = 242/335) of the dogs improved after behavior treatment. \u201cAggressive\u201d dogs (96%, N = 232/242) improved more than \u201canxious\u201d ones (4%; N = 10/242) (P 64 0.05). Moreover, owners of dogs with anxiety problems were significantly more prone to surrender the dog to a shelter or other people (P 64 0.05). Our work supports some previous findings and suggests some new information regarding factors associated with broad scale aggression and anxiety in domestic dogs. Anxiety problems appear more difficult and demanding for dog owners. A referral population is not likely representative of the entire population of dogs. To understand patterns of behavioral problems, we need more complete population data and we need data from dogs across their lifetime

Nanosecond Optical Quenching of Photoconductivity in a Bulk GaAs Switch

Persistent photoconductivity in copper-compensated, silicon-doped semi-insulating gallium arsenide with a time constant as large as 30 µs has been excited by sub-band-gap laser radiation of photon energy greater than 1 eV. This photoconductivity has been quenched on a nanosecond time scale by laser radiation of photon energy less than 1 eV. The proven ability to turn the switch conductance on and off on command, and to scale the switch to high power could make this semiconductor material the basis of an optically controlled pulsed-power closing and opening switch

Quantum discord dynamical behaviors due to initial system-cavity correlations

We analyze the roles of initial correlations between the two-qubit system and a dissipative cavity on quantum discord dynamics of two qubits. Considering two initial system-cavity states, we show that the initial system-cavity correlations not only can initially increase the two-qubit quantum discord but also would lead to a larger long-time quantum discord asymptotic value. Moreover, quantum discord due to initial correlations is more robust than the case of the initial factorized state. Finally, we show the initial correlations' importance for dynamics behaviors of mutual information and classical correlation