University of Lisbon

About: University of Lisbon is a education organization based out in Lisbon, Lisboa, Portugal. It is known for research contribution in the topics: Population & European union. The organization has 19122 authors who have published 48503 publications receiving 1102623 citations. The organization is also known as: Universidade de Lisboa & Lisbon University.

Why Do Firms Adopt E-Procurement Systems? Using Logistic Regression to Empirically Test a Conceptual Model

Abstract: Once the factors that foster the adoption of electronic-procurement systems (EPSs) are identified, economic agents may act accordingly and develop better programs in order to achieve their objectives. Toward the identification of such factors, a model that explains the adoption of EPS is developed, considering the technology-organization-environment framework as well as the institutional theory. This model was tested with data collected from the 2500 largest companies operating in Portugal. On the grounds of the f-test for equality of means, we found evidence that EPS adoption is positively and significantly associated to: 1) firm size; 2) technology competence; 3) the perception companies have about the EPS success of their competitors; 4) the extent of adoption among competitors; and 5) the readiness of the trading partners to perform electronic transactions. The logistic regression supplied further evidence that technology competence, firm size, extent of adoption among competitors, and trading partner readiness provide a reasonable estimate for each firm's likelihood to adopt EPS. We also found evidence that firms whose main activity is commerce are more likely to adopt EPS than are firms operating on manufacturing or services industries.

Search for Higgs boson pair production in the γ γ bb¯ final state with 13 TeV pp collision data collected by the ATLAS experiment

Abstract: A search is performed for resonant and non-resonant Higgs boson pair production in the $ \upgamma \upgamma b\overline{b} $ final state. The data set used corresponds to an integrated luminosity of 36.1 fb$^{−1}$ of proton-proton collisions at a centre-of-mass energy of 13 TeV recorded by the ATLAS detector at the CERN Large Hadron Collider. No significant excess relative to the Standard Model expectation is observed. The observed limit on the non-resonant Higgs boson pair cross-section is 0.73 pb at 95% confidence level. This observed limit is equivalent to 22 times the predicted Standard Model cross-section. The Higgs boson self-coupling (κ$_{λ}$ = λ$_{HHH}$/λ$_{HHH}^{SM}$ ) is constrained at 95% confidence level to −8.2 < κ$_{λ}$ < 13.2. For resonant Higgs boson pair production through $ X\to HH\to \upgamma \upgamma b\overline{b} $ , the limit is presented, using the narrow-width approximation, as a function of m$_{X}$ in the range 260 GeV < m$_{X}$ < 1000 GeV. The observed limits range from 1.1 pb to 0.12 pb over this mass range.

Adolescents’ perspectives on the barriers and facilitators of physical activity: a systematic review of qualitative studies

Abstract: This article examined qualitative studies of adolescents' perspectives about the facilitators and barriers of physical activity, published from 2007 to 2014. A systematic review of 'Web of Science', 'EBSCO', 'Psychinfo' and 'ERIC' databases was performed according to Preferred Reporting Items for Systematic reviews and Meta-analyses guidelines. The following keywords were used: 'physical activity' and 'physical education', each one individually associated with 'correlate', 'determinant', 'facilitator', 'barrier', 'factor influen*', and with 'qualitative', 'focus group', 'interview', "narrative'. Out of 3815 studies initially identified, due to inclusion and quality criteria, only 12 were fully reviewed. Studies' outcomes were analyzed through thematic analysis. The majority of these reported research with young adolescent girls. Few studies have considered the socioeconomic status influence. According to young people's perspectives, the main facilitators and hampering factors to their participation in physical activity were the following: attitude toward physical activity; motivation; perceptions of competence and body image; fun; influence of friends, family and physical education teachers and environmental physical activity opportunities. Specific life transition periods were referred only as a barrier to physical activity. Strategies of pedagogical actions and for developing physical activity intervention programs were discussed, in order to effectively promote the adoption of active lifestyles among youth.

Broken asymmetry of the human heartbeat: loss of time irreversibility in aging and disease.

Abstract: Time irreversibility, a fundamental property of nonequilibrium systems, should be of importance in assessing the status of physiological processes that operate over a wide range of scales. However, measurement of this property in living systems has been limited. We provide a computational method derived from basic physics assumptions to quantify time asymmetry over multiple scales and apply it to the human heartbeat time series in health and disease. We find that the multiscale time asymmetry index is highest for a time series from young subjects and decreases with aging or heart disease. Loss of time irreversibility may provide a new way of assessing the functionality of living systems that operate far from equilibrium.