Search results for "Positive"
showing 10 items of 1875 documents
Integrated photoabsorption strength and sum rules for a bound Dirac particle
1985
Relativistic effects in the integrated total photoabsorption cross section are discussed using a simple model of a Dirac particle bound in a central potential of scalar or vector type. The integrated strength is calculated explicitly and compared to a new relativistic extension of the TRK-sum rule using positive energy projection and to predictions from dispersion relations. M1 and E2 sum rules are also considered. In all cases the integrated strength exceeds the classical sum rule up to a few percent. The dispersion sum rule cannot be compared directly to the integrated strength since it contains a negative contribution from pair production in the potential field which is of the order of a…
Bell inequality, nonlocality and analyticity
2003
The Bell and the Clauser-Horne-Shimony-Holt inequalities are shown to hold for both the cases of complex and real analytic nonlocality in the setting parameters of Einstein-Podolsky-Rosen-Bohm experiments for spin 1/2 particles and photons, in both the deterministic and stochastic cases. Therefore, the theoretical and experimental violation of the inequalities by quantum mechanics excludes all hidden variables theories with that kind of nonlocality. In particular, real analyticity leads to negative definite correlations, in contradiction with quantum mechanics.
Dynamically screened vertex correction to $GW$
2020
Diagrammatic perturbation theory is a powerful tool for the investigation of interacting many-body systems, the self-energy operator $\mathrm{\ensuremath{\Sigma}}$ encoding all the variety of scattering processes. In the simplest scenario of correlated electrons described by the $GW$ approximation for the electron self-energy, a particle transfers a part of its energy to neutral excitations. Higher-order (in screened Coulomb interaction $W$) self-energy diagrams lead to improved electron spectral functions (SFs) by taking more complicated scattering channels into account and by adding corrections to lower order self-energy terms. However, they also may lead to unphysical negative spectral f…
Diagrammatic expansion for positive spectral functions beyond GW : Application to vertex corrections in the electron gas
2014
We present a diagrammatic approach to construct self-energy approximations within many-body perturbation theory with positive spectral properties. The method cures the problem of negative spectral functions which arises from a straightforward inclusion of vertex diagrams beyond the GW approximation. Our approach consists of a two-steps procedure: we first express the approximate many-body self-energy as a product of half-diagrams and then identify the minimal number of half-diagrams to add in order to form a perfect square. The resulting self-energy is an unconventional sum of self-energy diagrams in which the internal lines of half a diagram are time-ordered Green's functions whereas those…
"Table 1.2" of "Probing the effects of strong electromagnetic fields with charge-dependent directed flow in Pb-Pb collisions at the LHC"
2020
Directed flow negative hadrons 5-40%
"Table 1.1" of "Probing the effects of strong electromagnetic fields with charge-dependent directed flow in Pb-Pb collisions at the LHC"
2020
Directed flow positive hadrons 5-40%
Treatment options in obstructive sleep apnea
2022
AbstractTreatment of OSA with CPAP is currently the recommended treatment and has the greatest evidence of efficacy on AHI, symptoms and comorbidities. Symptomatic patients with moderate-severe OSA generally have good adherence to CPAP therapy, while those with mild OSA, female, young and generally paucisymptomatic, have lower CPAP adherence, especially in the medium and long term. The recent identification of different clinical and pathophysiological phenotypes of OSA has paved the way for alternative treatments to CPAP, leading to an increasingly personalized therapy. Weight loss and lifestyle modifications are highly recommended in all obese or overweight patients. Mandibular advancement…
Effects of carboxyamidotriazole on in vitro models of imatinib-resistant chronic myeloid leukemia.
2008
Although imatinib mesylate (IM) has revolutionized the treatment of chronic myeloid leukemia (CML), some patients develop resistance with progression of leukemia. Alternative or additional targeting of signaling pathways deregulated in bcr-abl-driven CML cells may provide a feasible option for improving clinical response and overcoming resistance. In this study, we show that carboxyamidotriazole (CAI), an orally bioavailable calcium influx and signal transduction inhibitor, is equally effective in inhibiting the proliferation and bcr-abl dependent- and independent-signaling pathways in imatinib-resistant CML cells. CAI inhibits phosphorylation of cellular proteins including STAT5 and CrkL a…
Metabolic Impacts of Confinement during the COVID-19 Pandemic Due to Modified Diet and Physical Activity Habits
2020
While the detrimental effects of a chronic positive energy balance due to a sedentary lifestyle have been well established, the impacts of a short period of abruptly reduced physical activity and overeating arising from strict confinement due to the COVID-19 pandemic will soon start to emerge. To reasonably anticipate major consequences according to the available evidence, we hereby review the literature for studies that have explored the health impacts of several weeks of a reduction in physical activity and daily step-count combined with modified eating habits. These studies identify as main metabolic consequences increases in insulin resistance, total body fat, abdominal fat and inflamma…
The Educational Construction of a Social Person and the Unexpected Development of a Human Being
2008
The phenomenon of migratory flows, always present in human history, is today analyzed in such a way as to define a boundary, an us and a them. From the point of view of the host society, the problem is seen in terms of the legitimate conditions of “entry”. But in actual fact, migratory flow modifies the social composition of the political community and therefore could lead to the obligation of also observing phenomena from the migrant’s point of view.