333 research outputs found
Epistemic and Ontic Quantum Realities
Quantum theory has provoked intense discussions about its interpretation since its pioneer days. One of the few scientists who have been continuously engaged in this development from both physical and philosophical perspectives is Carl Friedrich von Weizsaecker. The questions he posed were and are inspiring for many, including the authors of this contribution. Weizsaecker developed Bohr's view of quantum theory as a theory of knowledge. We show that such an epistemic perspective can be consistently complemented by Einstein's ontically oriented position
Local Operations and Completely Positive Maps in Algebraic Quantum Field Theory
Einstein introduced the locality principle which states that all physical
effect in some finite space-time region does not influence its space-like
separated finite region. Recently, in algebraic quantum field theory, R\'{e}dei
captured the idea of the locality principle by the notion of operational
separability. The operation in operational separability is performed in some
finite space-time region, and leaves unchanged the state in its space-like
separated finite space-time region. This operation is defined with a completely
positive map. In the present paper, we justify using a completely positive map
as a local operation in algebraic quantum field theory, and show that this
local operation can be approximately written with Kraus operators under the
funnel property
A Qualified Kolmogorovian Account of Probabilistic Contextuality
We describe a mathematical language for determining all possible patterns of
contextuality in the dependence of stochastic outputs of a system on its
deterministic inputs. The central notion is that of all possible couplings for
stochastically unrelated outputs indexed by mutually incompatible values of
inputs. A system is characterized by a pattern of which outputs can be
"directly influenced" by which inputs (a primitive relation, hypothetical or
normative), and by certain constraints imposed on the outputs (such as
Bell-type inequalities or their quantum analogues). The set of couplings
compatible with these constraints represents a form of contextuality in the
dependence of outputs on inputs with respect to the declared pattern of direct
influences.Comment: Lecture Notes in Computer Science 8369, 201-212 (2014
The Association of State Opioid Misuse Prevention Policies With Patient‐ and Provider‐Related Outcomes: A Scoping Review
Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/154648/1/milq12436.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/154648/2/milq12436_am.pd
Higher Height, Higher Ability: Judgment Confidence as a Function of Spatial Height Perception
Based on grounded cognition theories, the current study showed that judgments about ability were regulated by the subjects' perceptions of their spatial height. In Experiment 1, we found that after seeing the ground from a higher rather than lower floor, people had higher expectations about their performance on a knowledge test and assigned themselves higher rank positions in a peer comparison evaluation. In Experiment 2, we examined the boundary conditions of the spatial height effects and showed that it could still occur even if we employed photos rather than actual building floors to manipulate the perceptions of spatial heights. In addition, Experiment 2 excluded processing style as an explanation for these observations. In Experiment 3, we investigated a potential mechanism for the spatial height effect by manipulating the scale direction in the questionnaire. Consequently, consistent with our representational dependence account, the effect of spatial heights on ability judgments was eliminated when the mental representation of ability was disturbed by a reverse physical representation. These results suggest that people's judgments about their ability are correlated with their spatial perception
Large scale analytic calculations in quantum field theories
We present a survey on the mathematical structure of zero- and single scale
quantities and the associated calculation methods and function spaces in higher
order perturbative calculations in relativistic renormalizable quantum field
theories.Comment: 25 pages Latex, 1 style fil
On the Integrand-Reduction Method for Two-Loop Scattering Amplitudes
We propose a first implementation of the integrand-reduction method for
two-loop scattering amplitudes. We show that the residues of the amplitudes on
multi-particle cuts are polynomials in the irreducible scalar products
involving the loop momenta, and that the reduction of the amplitudes in terms
of master integrals can be realized through polynomial fitting of the
integrand, without any apriori knowledge of the integral basis. We discuss how
the polynomial shapes of the residues determine the basis of master integrals
appearing in the final result. We present a four-dimensional constructive
algorithm that we apply to planar and non-planar contributions to the 4- and
5-point MHV amplitudes in N=4 SYM. The technique hereby discussed extends the
well-established analogous method holding for one-loop amplitudes, and can be
considered a preliminary study towards the systematic reduction at the
integrand-level of two-loop amplitudes in any gauge theory, suitable for their
automated semianalytic evaluation.Comment: 26 pages, 11 figure
Stochastic Gravity: Theory and Applications
Whereas semiclassical gravity is based on the semiclassical Einstein equation
with sources given by the expectation value of the stress-energy tensor of
quantum fields, stochastic semiclassical gravity is based on the
Einstein-Langevin equation, which has in addition sources due to the noise
kernel.In the first part, we describe the fundamentals of this new theory via
two approaches: the axiomatic and the functional. In the second part, we
describe three applications of stochastic gravity theory. First, we consider
metric perturbations in a Minkowski spacetime: we compute the two-point
correlation functions for the linearized Einstein tensor and for the metric
perturbations. Second, we discuss structure formation from the stochastic
gravity viewpoint. Third, we discuss the backreaction of Hawking radiation in
the gravitational background of a quasi-static black hole.Comment: 75 pages, no figures, submitted to Living Reviews in Relativit
Physics of Neutron Star Crusts
The physics of neutron star crusts is vast, involving many different research
fields, from nuclear and condensed matter physics to general relativity. This
review summarizes the progress, which has been achieved over the last few
years, in modeling neutron star crusts, both at the microscopic and macroscopic
levels. The confrontation of these theoretical models with observations is also
briefly discussed.Comment: 182 pages, published version available at
<http://www.livingreviews.org/lrr-2008-10
Impacto da exposição académica no estado de saúde de estudantes universitários
OBJECTIVE: To assess the impact of academic life on health status of university students. METHODS: Longitudinal study including 154 undergraduate students from the Universidade de Aveiro, Portugal, with at least two years of follow-up observations. Sociodemographic and behavioral characteristics were collected using questionnaires. Students' weight, height, blood pressure, serum glucose, serum lipids and serum homocysteine levels were measured. Regression analysis was performed using linear mixed-effect models, allowing for random effects at the participant level. RESULTS: A higher rate of dyslipidemia (44.0% vs. 28.6%), overweight (16.3% vs. 12.5%) and smoking (19.3% vs. 0.0%) was found among students exposed to the academic life when compared to freshmen. Physical inactivity was about 80%. Total cholesterol, high density lipoprotein-cholesterol (HDL-C), triglycerides, systolic blood pressure, and physical activity levels were significantly associated with gender (p<0.001). Academic exposure was associated with increased low density lipoprotein-cholesterol (LDL-C) levels (about 1.12 times), and marginally with total cholesterol levels (p=0.041). CONCLUSIONS: High education level does not seem to have a protective effect favoring a healthier lifestyle and being enrolled in health-related areas does not seem either to positively affect students' behaviors. Increased risk factors for non-transmissible diseases in university students raise concerns about their well-being. These results should support the implementation of health promotion and prevention programs at universities.OBJETIVO: Avaliar a influência da vida académica na saúde de estudantes universitários.
MÉTODOS: Estudo longitudinal envolvendo 154 estudantes de graduação da Universidade de Aveiro, Portugal, por pelo menos dois anos de
acompanhamento. Características sociodemográfi cas e comportamentais foram recordados, por meio de questionários. Foram medidos peso, altura,pressão arterial, glicemia, perfil lipídico e os níveis séricos de homocisteína
dos alunos. Foi realizada análise de regressão com modelos lineares mistos
considerando as medidas repetidas de cada sujeito.
RESULTADOS: Estudantes expostos à vida académica, quando comparados àqueles de ingresso recente à universidade apresentaram proporção mais elevada de dislipidemia (44,0% versus 28,6%), sobrepeso (16,3% versus
12,5%) e tabagismo (19,3% versus 0,0%). No geral, foi observada alta proporção de sedentarismo (cerca de 80%). O colesterol total, lipoproteína de alta densidade, triglicérides, pressão arterial sistólica e níveis de atividade física apresentaram associação signifi cativa com o género (p < 0,001). A exposição académica apresentou-se associada com o aumento dos níveis das lipoproteínas de baixa densidade (cerca de 1,12 vezes), e marginalmente com os níveis de
colesterol total (p = 0,041).
CONCLUSÕES: Nem o alto nível de instrução parece ter papel protetor na adoção de estilo de vida saudável, tampouco o envolvimento com áreas de saúde muda o comportamento dos estudantes. Altas proporções de fatores
de risco para doenças não-transmissíveis em jovens universitários podem afetar seu bem-estar. Os resultados podem servir de apoio às universidades no desenvolvimento de programas de prevenção e promoção da saúde
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