2,750 research outputs found
Combined risk factors for melanoma in a Mediterranean population
A case–control study of non-familial melanoma including 183 incident cases and 179 controls was conducted in North-Eastern Italy to identify important risk factors and determine how combination of these affects risk in a Mediterranean population. Presence of dysplastic nevi (OR = 4.2, 95% CI = 2.4–7.4), low propensity to tan (OR = 2.4, 95% CI = 1.1–5.0), light eye (OR = 2.4, 95% CI = 1.1–5.2), and light skin colour (OR = 4.1, 95% CI = 1.4–12.1) were significantly associated with melanoma risk after adjustment for age, gender and pigmentation characteristics. A chart which identifies melanoma risk associated with combinations of these factors is presented; it can be used to identify subjects who would most benefit from preventive measures in Mediterranean populations. According to the combination of these factors, a relative risk range from 1 to 98.5 was found. Light skin colour, high number of sunburns with blistering, and low propensity to tan were significantly associated with melanoma thickness, possibly indicating that individuals with these characteristics underestimate their risk and seek attention when their lesion is already advanced. © 2001 Cancer Research Campaig
Non-Abelian Quantum Transport and Thermosqueezing Effects
Modern quantum experiments provide examples of transport with non-commuting
quantities, offering a tool to understand the interplay between thermal and
quantum effects. Here we set forth a theory for non-Abelian transport in the
linear response regime. We show how transport coefficients obey Onsager
reciprocity and identify non-commutativity-induced reductions in the entropy
production. As an example, we study heat and squeezing fluxes in bosonic
systems, characterizing a set of thermosqueezing coefficients with potential
applications in metrology and heat-to-work conversion in the quantum regime.Comment: 7+7 pages, 2 figure
Vortex Scattering and Intercommuting Cosmic Strings on a Noncommutative Spacetime
We study the scattering of noncommutative vortices, based on the
noncommutative field theory developed in [Phys. Rev. D 75, 045009 (2007)], as a
way to understand the interaction of cosmic strings. In the center-of-mass
frame, the effects of noncommutativity vanish, and therefore the reconnection
of cosmic strings occurs in an identical manner to the commutative case.
However, when scattering occurs in a frame other than the center-of-mass frame,
strings still reconnect but the well known 90-degree scattering no longer need
correspond to the head on collision of the strings, due to the breakdown of
Lorentz invariance in the underlying noncommutative field theory.Comment: 18 pages, 2 figure
Energy barriers between metastable states in first-order quantum phase transitions
A system of neutral atoms trapped in an optical lattice and dispersively coupled to the field of an optical cavity can realize a variation of the Bose-Hubbard model with infinite-range interactions. This model exhibits a first-order quantum phase transition between a Mott insulator and a charge density wave, with spontaneous symmetry breaking between even and odd sites, as was recently observed experimentally [Landig, Nature (London) 532, 476 (2016)10.1038/nature17409]. In the present paper, we approach the analysis of this transition using a variational model which allows us to establish the notion of an energy barrier separating the two phases. Using a discrete WKB method, we then show that the local tunneling of atoms between adjacent sites lowers this energy barrier and hence facilitates the transition. Within our simplified description, we are thus able to augment the phase diagram of the model with information concerning the height of the barrier separating the metastable minima from the global minimum in each phase, which is an essential aspect for the understanding of the reconfiguration dynamics induced by a quench across a quantum critical point.Fil: Wald, Sascha. Sissa - International School For Advanced Studies; Italia. Universitat Saarland; AlemaniaFil: Timpanaro, AndrĂ© M.. Universidade Federal Do Abc; BrasilFil: Cormick, Maria Cecilia. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - CĂłrdoba. Instituto de FĂsica Enrique Gaviola. Universidad Nacional de CĂłrdoba. Instituto de FĂsica Enrique Gaviola; ArgentinaFil: Landi, Gabriel T.. Universidade de Sao Paulo; Brasi
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