7,720 research outputs found

    A general search for new phenomena with the ATLAS detector in pp collisions at √s = 7TeV

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    We present results of a Model-Independent General Search for new physics in proton-proton collisions at √s = 7TeV. Data collected by the ATLAS experiment in 2011, for a total integrated luminosity of 4.7 fb−1 has been used. All event topologies involving isolated electrons, photons, muons, jets, b-jets and missing transverse momentum are subdivided according to their final states into exclusive classes. A search algorithm is then used to scan all classes for deviations from the Monte Carlo simulated background in the distribution of the scalar sum of transverse momenta. No excess over the Standard Model expectation is observed

    Heterogeneity of innovative, collaborative, and productive firm-level processes

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    This thesis addresses a set of interrelated topics that contribute to both structural and empirical fields of the economics of innovation. First, we consider the role of imperfect competition in product and labor markets in shaping the productivity of a firm. Second, we model and evaluate the expected correlations present among firms' R&D cooperative choices due to both firm- and sector-level heterogeneity. In the last study, we develop and estimate a structural dynamic monopoly model to quantify the linkages between R&D spending, cooperation, and innovation investment choices, and endogenous productivity.

    Lower Bounds for Heights in Relative Galois Extensions

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    The goal of this paper is to obtain lower bounds on the height of an algebraic number in a relative setting, extending previous work of Amoroso and Masser. Specifically, in our first theorem we obtain an effective bound for the height of an algebraic number α\alpha when the base field K\mathbb{K} is a number field and K(α)/K\mathbb{K}(\alpha)/\mathbb{K} is Galois. Our second result establishes an explicit height bound for any non-zero element α\alpha which is not a root of unity in a Galois extension F/K\mathbb{F}/\mathbb{K}, depending on the degree of K/Q\mathbb{K}/\mathbb{Q} and the number of conjugates of α\alpha which are multiplicatively independent over K\mathbb{K}. As a consequence, we obtain a height bound for such α\alpha that is independent of the multiplicative independence condition

    Understanding Consumers\u27 Acceptance of Online Purchasing

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    This paper examines previous Technology Acceptance Model (TAM)-related studies in order to provide an expanded model that explains consumers’ acceptance of online purchasing. Our model provides extensions to the original TAM by including constructs such as social influence and voluntariness; it also examines the impact of external variables including trust, privacy, risk, and e-loyalty. We surveyed consumers in the United States and Australia. Our findings suggest that our expanded model serves as a very good predictor of consumers’ online purchasing behaviors. The linear regression model shows a respectable amount of variance for Behavioral Intention (R2 = .627). Suggestions are provided for the practitioner and ideas are presented for future research

    Cellular automata on regular rooted trees

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    We study cellular automata on regular rooted trees. This includes the characterization of sofic tree shifts in terms of unrestricted Rabin automata and the decidability of the surjectivity problem for cellular automata between sofic tree shifts

    CO2 and HCO3- uptake in marine diatoms acclimated to different CO2 concentrations.

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    Rates of cellular uptake of CO2 and HCO3- during steady-state photosynthesis were measured in the marine diatoms Thalassiosira weissflogii and Phaeodactylum tricornutum, acclimated to CO2 partial pressures of 36, 180, 360, and 1,800 ppmv. In addition, in vivo activity of extracellular (eCA) and intracellular (iCA) carbonic anhydrase was determined in relation to CO2 availability. Both species responded to diminishing CO2 supply with an increase in eCA and iCA activity. In P. tricornutum, eCA activity was close to the detection limit at higher CO2 concentrations. Simultaneous uptake of CO2 and HCO3- was observed in both diatoms. At air-equilibrated CO2 levels (360 ppmv), T. weissflogii took up CO2 and HCO3- at approximately the same rate, whereas CO2 uptake exceeded HCO3- uptake by a factor of two in P. tricornutum. In both diatoms, CO2 :HCO3- uptake ratios progressively decreased with decreasing CO2 concentration, whereas substrate affinities of CO2 and HCO3- uptake increased. Half-saturation concentrations were always <=5 mM CO2 for CO2 uptake and <700 mM HCO3- for HCO3- uptake. Our results indicate the presence of highly efficient uptake systems for CO2 and HCO3- in both diatoms at concentrations typically encountered in ocean surface waters and the ability to adjust uptake rates to a wide range of inorganic carbon supply

    Investigating stress in commuting university students

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    Commuting can be considered as a chronic stressor, since it is often experienced as an unpleasant condition which negatively impacts on the individual psychological, physical and social well-being. Stress becomes dysfunctional and pathological when the individual negatively appraise specific situations. According to the National Institute for Statistics (ISTAT) commuters are people daily travelling out of their residence town for working or studying purposes irrespectively of the distance covered or the mean travel duration. To date, the most studies have been focused on stress among commuting workers; however, it is noteworthy that students represent a wide proportion of commuting population in Italy (about the 23%, conforming to a survey carried out by CENSIS, Centro Studi Investimenti Sociali). In consideration of these data, it is important to cast light on the consequences of commuting on students\u2019 skills and psycho-physical well-being. Present study was aimed at investigating stress among commuting university students, in order to provide answers for some important questions: does commuting affect students\u2019 performance? Does commuting affect daily psychological and physical well-being? What are the commuting characteristics mainly involved in affecting student\u2019s performance and well-being? Three-thousand three-hundred and fifteen commuting students attending the University of Palermo enrolled the study. Non valid data (inconsistent answers) were excluded from the analyses and the final sample consisted of 2949 participants: 60.1% (N = 1773) were females and 39.9% (N = 1176) were males. All students provided socio-anagraphic data and completed an ad hoc self-report questionnaire comprising 20 items. A section of the questionnaire was aimed at collecting information concerning daily commuting, such as place of study (inside or outside the town of residence), estimated daily covered distance, etc. The other section was developed to investigate how commuting students appraise their commuting condition; it investigates three areas: perception of commuting, psycho-physical well-being and disease associated with commuting stressors. The main finding of present study highlights the existence of important differences between commuting students on the basis of means of transportation. It emerged that those using public transports (train, bus, metro) reported a more negative evaluation of their commuting and lower psycho-physical well-being levels than those travelling by private transports. In particular, students travelling by motorcycle described their daily commuting as positive and reported good psycho-physical conditions when arriving at university. This result is in line with previous literature indicating that control and predictability are important subjective factors which mediate the relationship between commuting and stress. People using public transports usually face with uncontrollable events (for example delays or crowding) which facilitate a negative appraisal of commuting. When this is chronically experienced, it may lead to stress and thus lack of energy, irritability, negative mood and difficulties in concentration. All these factors can negatively impact on student\u2019 performance


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    Lo stress \ue8 un insieme di modificazioni fisiologiche, cognitive, emotive e comportamentali di cui l\u2019individuo ha esperienza nel momento in cui \ue8 richiesto un adattamento alle circostanze ambientali presenti: si configura pertanto come una reazione generale a situazioni specifiche e, non ha una connotazione positiva o negativa, svolgendo primariamente una funzione di tipo adattivo. Ci\uf2 che rende disfunzionale e \u201cpatologico\u201d lo stress \ue8 il modo in cui l\u2019individuo valuta la situazione con la quale si trova a rapportarsi: in questi casi si parla pertanto di distress, ovvero \u201cstress negativo\u201d (Selye, 1956). Gli stimoli e le situazioni che, valutate negativamente, determinano una reazione di distress sono definiti stressors; questi possono essere acuti (si verificano una sola volta e per un periodo limitato di tempo) oppure cronici (di lunga durata). A loro volta, gli stressors cronici possono essere intermittenti o propriamente cronici. Nel primo caso, si presentano a intervalli di tempo regolari, hanno una durata limitata e perci\uf2 sono pi\uf9 o meno prevedibili; nel secondo, invece, sono rappresentati da situazioni di lunga durata, che permeano la vita dell\u2019individuo e che diventano stressanti nel momento in cui ostacolano in maniera persistente il perseguimento degli obiettivi della persona. Due sono le reazioni fisiologiche principali che caratterizzano la risposta di stress: muscolari (tensione muscolare o immobilizzazione) e neurovegetative (dovute a un\u2019eccessiva stimolazione del Sistema Nervoso Autonomo simpatico). Gli effetti di queste reazioni fisiologiche, andando a combinarsi con quella che \ue8 l\u2019interpretazione che la persona da della situazione e la propria esperienza emotiva, determinano alcuni dei principali sintomi riferiti legati allo stress: emicrania, tachicardia, iperventilazione, difficolt\ue0 di concentrazione, umore depresso, irritabilit\ue0, stanchezza, affaticamento