A Quantum Adiabatic Evolution Algorithm Applied to Random Instances of an NP-Complete Problem

A quantum system will stay near its instantaneous ground state if the Hamiltonian that governs its evolution varies slowly enough. This quantum adiabatic behavior is the basis of a new class of algorithms for quantum computing. We test one such algorithm by applying it to randomly generated, hard, instances of an NP-complete problem. For the small examples that we can simulate, the quantum adiabatic algorithm works well, and provides evidence that quantum computers (if large ones can be built) may be able to outperform ordinary computers on hard sets of instances of NP-complete problems.Comment: 15 pages, 6 figures, email correspondence to [email protected] ; a shorter version of this article appeared in the April 20, 2001 issue of Science; see http://www.sciencemag.org/cgi/content/full/292/5516/47

The Paths to Choreography Extraction

Choreographies are global descriptions of interactions among concurrent components, most notably used in the settings of verification (e.g., Multiparty Session Types) and synthesis of correct-by-construction software (Choreographic Programming). They require a top-down approach: programmers first write choreographies, and then use them to verify or synthesize their programs. However, most existing software does not come with choreographies yet, which prevents their application. To attack this problem, we propose a novel methodology (called choreography extraction) that, given a set of programs or protocol specifications, automatically constructs a choreography that describes their behavior. The key to our extraction is identifying a set of paths in a graph that represents the symbolic execution of the programs of interest. Our method improves on previous work in several directions: we can now deal with programs that are equipped with a state and internal computation capabilities; time complexity is dramatically better; we capture programs that are correct but not necessarily synchronizable, i.e., they work because they exploit asynchronous communication

Recent environmental changes in the area of La Maddalena Harbour (Sardinia, Italy): data from mollusks and benthic foraminifera

Mollusks and benthic foraminifera are reliable tools to paleo-environmental reconstructions because they commonly occur in most marine habitats and are sensitive to major and short-lived changes of environmental drivers, induced by both natural and anthropogenic events. Their community structure provides useful information about the characteristics of their habitat and some species are sensitive to specific environmental controls. Features such as changes in species composition and community, or variation in test morphology provide evidence of fluctuation of several environmental factors. Therefore, both mollusks and benthic foraminifera can be used as an efficient method for identifying the history and ecological trajectory of marine ecosystems. This study focuses on the macro- (mollusks) and micropaleontological (benthic foraminifera) study of a 3 m long sediment core collected in the former military arsenal of the La Maddalena harbor (N Sardinia, Italy), at a depth of 15 m. The core site is located on the S-E coast of La Maddalena island, that underwent a complex history of human occupation along with natural environmental evolution and human-derived pressures. We aimed to reconstruct the main environmental changes recorded in the fossil benthic communities along the core, and to propose the most likely factors that caused these changes. Both mollusks and benthic foraminifera have been picked from the core, identified at genus/species level and counted. Ecological indications for each species have been extracted from literature. Univariate and multivariate statistics have been applied to highlight the community dynamics. More than 90 species of benthic foraminifera have been identified, and 101 mollusk species (846 specimens). The foraminifera diversity indices show a general reduction from the first 50 cm downcore. This slight decline is accompanied by changes in foraminiferal assemblages. The results concerning changes in foraminiferal species composition, their abundance and biodiversity, supported by statistical analyses (cluster analysis), allowed identification of three major foraminiferal associations corresponding to different marine coastal settings. The same results have been obtained by using mollusks and their ecological significance in the framework of benthic marine bionomics. Species are related to infralittoral vegetated bottom such as Posidonia meadows (HP) or photophilous algae through the core, but with variation in percentage of abundance, and HP species decreases from the bottom to the top, whereas species related to muddy bottom follow the opposite trend (coastal detritic mud, deep mud). This testifies that the area underwent a progressive reduction of Posidonia meadows and light-loving algae with a shift toward muddy bottoms, possibly related to the effect of the intensive renovation works of the harbor area. Moreover, radiocarbon dating obtained from Cerithium specimens indicated that the sedimentation rate increases in the upper portion of the core, according to the ecological signal reconstructed by the analysis of the mollusk assemblage

Distributed information consensus filters for simultaneous input and state estimation

This paper describes the distributed information filtering where a set of sensor networks are required to simultaneously estimate input and state of a linear discrete-time system from collaborative manner. Our research purpose is to develop a consensus strategy in which sensor nodes communicate within the network through a sequence of Kalman iterations and data diffusion. A novel recursive information filtering is proposed by integrating input estimation error into measurement data and weighted information matrices. On the fusing process, local system state filtering transmits estimation information using the consensus averaging algorithm, which penalizes the disagreement in a dynamic manner. A simulation example is provided to compare the performance of the distributed information filtering with optimal Gillijins–De Moor’s algorithm

Typing and distribution of Plum pox virus isolates in Romania

Plum pox or Sharka, caused by Plum pox virus (PPV) is considered the most destructive disease of plum. Although PPV is widespread in all plum growing areas of Romania and causes serious yield losses, little is known about the variability of its isolates at a country level. For this reason, a large-scale study was performed with the aim of obtaining a picture of the prevalence and distribution of PPV strains in plum. During a three year survey, 200 PPV isolates collected from 23 different plum orchards from Transylvania, Moldavia and Muntenia areas were investigated. DASELISA and IC-RT-PCR were used for PPV detection. PPV strains were serologically determined by TAS-ELISA using PPV-D and PPV-M specific monoclonal antibodies. Molecular strain typing was done by IC/RT-PCR targeting three genomic regions corresponding to (Cter)CP, (Cter)NIb/(Nter)CP and CI. RFLP analysis was used to distinguish D and M strains, based on the RsaI polymorphism located in (Cter)CP. To confirm the presence of PPV-Rec strain, 13 PCR products spanning the (Cter)NIb/(Nter)CP were sequenced. Overall results showed that in Romania the predominant strain is PPV-D (73%), followed, with a much lower frequency, by PPV-Rec (14%). Mixed infections (PPV-D+PPVRec), which might generate additional variation by recombination, are also frequent (13%).Keywords: Romania, PPV strains, DAS/TAS-ELISA, IC/RT-PCR, RFLP, sequencin

Perception of nurses’ professional identity during the first wave of COVID-19 pandemic infections

Background and aim of the work: The main purpose of this study is to investigate on the experience of nurses working in the Covid-19 area focusing on their role’s perception. In particular, we explored the nurses’ perception of job satisfaction in relation to the images sent back by public opinion through the mass media and social communication channels. During the first wave of Covid-19 nurses have acquired media visibility, but their feeling is represented more by the discomfort of finding themselves suddenly glorified in the face of a lack of professional, social, and economic recognition. Materials and methods: A Mix-Method methodology and convenience sampling was adopted, on the population of professionals and students in post-graduate specializations, belonging to the Department of Medicine and Surgery of the University of Parma, and by nurses from the ASST-Bergamo Est, Lombardia Italy, who worked in the Covid emergency during the first wave of the pandemic, from February 2020 to May 2020. In the quantitative phase Stamm’s Professional Quality of Life Scale - ProQOL was administered to 89 respondents through a Google Form, In the qualitative phase, 3 Focus Groups were conducted on a total of 17 students. Results: At the ProQOL questionnaire, a moderate score was found in the Compassion Satisfaction scale (CF = 38.28) and in the Secondary Traumatic Stress subscale (STS-24.33), while low values emerged in the Burnout subscale (BO = 16.02). Five specific topics emerged from the focus groups: Professional collaboration, Job satisfaction, Nurse’s personal skills, Failure to protect the public image and the nursing profession. Conclusions: The professional collaboration, union with the work team, sense of solidarity, job satisfaction, professional growth, and awareness of one’s role seem to have worked favorably on Compassion Satisfaction, while keeping Compassion Fatigue levels under control

Performance of fully instrumented detector planes of the forward calorimeter of a Linear Collider detector

Detector-plane prototypes of the very forward calorimetry of a future detector at an e+e- collider have been built and their performance was measured in an electron beam. The detector plane comprises silicon or GaAs pad sensors, dedicated front-end and ADC ASICs, and an FPGA for data concentration. Measurements of the signal-to-noise ratio and the response as a function of the position of the sensor are presented. A deconvolution method is successfully applied, and a comparison of the measured shower shape as a function of the absorber depth with a Monte-Carlo simulation is given.Comment: 25 pages, 32 figures, revised version following comments from referee

Measurement of shower development and its Moli\`ere radius with a four-plane LumiCal test set-up

A prototype of a luminometer, designed for a future e+e- collider detector, and consisting at present of a four-plane module, was tested in the CERN PS accelerator T9 beam. The objective of this beam test was to demonstrate a multi-plane tungsten/silicon operation, to study the development of the electromagnetic shower and to compare it with MC simulations. The Moli\`ere radius has been determined to be 24.0 +/- 0.6 (stat.) +/- 1.5 (syst.) mm using a parametrization of the shower shape. Very good agreement was found between data and a detailed Geant4 simulation.Comment: Paper published in Eur. Phys. J., includes 25 figures and 3 Table

No more, no less - A formal model for serverless computing

Serverless computing, also known as Functions-as-a-Service, is a recent paradigm aimed at simplifying the programming of cloud applications. The idea is that developers design applications in terms of functions, which are then deployed on a cloud infrastructure. The infrastructure takes care of executing the functions whenever requested by remote clients, dealing automatically with distribution and scaling with respect to inbound traffic. While vendors already support a variety of programming languages for serverless computing (e.g. Go, Java, Javascript, Python), as far as we know there is no reference model yet to formally reason on this paradigm. In this paper, we propose the first formal programming model for serverless computing, which combines ideas from both the $\lambda$-calculus (for functions) and the $\pi$-calculus (for communication). To illustrate our proposal, we model a real-world serverless system. Thanks to our model, we are also able to capture and pinpoint the limitations of current vendor technologies, proposing possible amendments