161 research outputs found
Quantum Google in a Complex Network
We investigate the behavior of the recently proposed quantum Google
algorithm, or quantum PageRank, in large complex networks. Applying the quantum
algorithm to a part of the real World Wide Web, we find that the algorithm is
able to univocally reveal the underlying scale-free topology of the network and
to clearly identify and order the most relevant nodes (hubs) of the graph
according to their importance in the network structure. Moreover, our results
show that the quantum PageRank algorithm generically leads to changes in the
hierarchy of nodes. In addition, as compared to its classical counterpart, the
quantum algorithm is capable to clearly highlight the structure of secondary
hubs of the network, and to partially resolve the degeneracy in importance of
the low lying part of the list of rankings, which represents a typical
shortcoming of the classical PageRank algorithm. Complementary to this study,
our analysis shows that the algorithm is able to clearly distinguish scale-free
networks from other widespread and important classes of complex networks, such
as Erd\H{o}s-R\'enyi networks and hierarchical graphs. We show that the ranking
capabilities of the quantum PageRank algorithm are related to an increased
stability with respect to a variation of the damping parameter that
appears in the Google algorithm, and to a more clearly pronounced power-law
behavior in the distribution of importance among the nodes, as compared to the
classical algorithm. Finally, we study to which extent the increased
sensitivity of the quantum algorithm persists under coordinated attacks of the
most important nodes in scale-free and Erd\H{o}s-R\'enyi random graphs
Growth of graph states in quantum networks
We propose a scheme to distribute graph states over quantum networks in the
presence of noise in the channels and in the operations. The protocol can be
implemented efficiently for large graph sates of arbitrary (complex) topology.
We benchmark our scheme with two protocols where each connected component is
prepared in a node belonging to the component and subsequently distributed via
quantum repeaters to the remaining connected nodes. We show that the fidelity
of the generated graphs can be written as the partition function of a classical
Ising-type Hamiltonian. We give exact expressions of the fidelity of the linear
cluster and results for its decay rate in random graphs with arbitrary
(uncorrelated) degree distributions.Comment: 16 pages, 7 figure
Thermodynamic formalism for dissipative quantum walks
We consider the dynamical properties of dissipative continuous-time quantum
walks on directed graphs. Using a large-deviation approach we construct a
thermodynamic formalism allowing us to define a dynamical order parameter, and
to identify transitions between dynamical regimes. For a particular class of
dissipative quantum walks we propose a quantum generalization of the the
classical PageRank vector, used to rank the importance of nodes in a directed
graph. We also provide an example where one can characterize the dynamical
transition from an effective classical random walk to a dissipative quantum
walk as a thermodynamic crossover between distinct dynamical regimes.Comment: 8 page
Very elderly patients with venous thromboembolism on oral anticoagulation with VKAs or DOACs. results from the prospective multicenter START2-register study
Introduction: Few data are available on the safety of anticoagulation in very elderly patients treated with Vitamin K antagonists (VKAs) and direct oral anticoagulants (DOACs) for venous thromboembolism (VTE). Methods: We carried out a prospective cohort study on VTE patients aged ≥85 years enrolled in the Survey on anticoagulaTed pAtients RegisTer (START2-Register) on treatment with VKAs or DOACs, with the aim to evaluate mortality, bleeding and thrombotic rates (venous and arterial). Results: We enrolled 272 patients, 58.7% on VKA and 41.3% on DOACs. Baseline characteristics were similar between treatment groups, with a higher prevalence of renal failure in VKAs patients and of a history of bleeding and previous stroke/TIA in DOACs patients. During follow-up of 429 patient-years, 15 major and non-major clinically relevant bleedings were recorded (rate 3.5 × 100 pt-yrs), 5 were major bleeds (rate 1.2 × 100 pt-yrs), 1 in a patient on aspirin (rate 4.3 × 100 pt-yrs). Bleeding rate was higher in patients on DOACs (crude HR 4.7; 95%CI 1.5–15.01). Eight thrombotic events were recorded (rate 1.9 × 100 pt-yrs), 3 recurrent VTE and 5 stroke/TIA. Overall, the incidence of thrombotic events was higher in DOACs patients (crude HR 4.5; 95% CI 1.5; 13.3). The rate of recurrent VTE was similar in the two group. Mortality rate was significantly lower in DOACs patients (crude HR 0.30; 95% CI 0.1;0.9). Conclusion: A higher bleeding risk was found in very elderly VTE patients on DOACs despite the wide use of low-dosages. Similarly a higher thrombotic risk was found while the incidence of recurrent VTE was low and similar between the groups. Mortality rate were significantly lower in DOACs patients
Hashimotos’ thyroiditis: Epidemiology, pathogenesis, clinic and therapy
Hashimoto's thyroiditis (HT), the most frequent autoimmune thyroid disorders (AITDs), is the leading cause of hypothyroidism in the iodine-sufficient areas of the world. About 20-30% of patients suffers from HT, whose cause is thought to be a combination of genetic susceptibility and environmental factors that causes the loss of immunological tolerance, with a consequent autoimmune attack to the thyroid tissue and appearance of the disease. The pathologic features of lymphocytic infiltration, especially of T cells, and follicular destruction are the histological hallmark of autoimmune thyroiditis (AIT), that lead to gradual atrophy and fibrosis. An important role in the immune-pathogenesis of AITDs is due to chemokines and cytokines. In about 20% of patients, AITDs are associated with other organ specific/systemic autoimmune disorders. Many studies have demonstrated the relationship between papillary thyroid cancer and AITD. The treatment of hypothyroidism, as result of AIT, consists in daily assumption of synthetic levothyroxine
Gut microbiota as target for innovative strategies against food allergy.
The dramatic increase in food allergy prevalence and severity globally requires effective strategies. Food allergy derives from a defect in immune tolerance mechanisms. Immune tolerance is modulated by gut microbiota function and structure, and microbiome alterations (dysbiosis) have a pivotal role in the development of food allergy. Environmental factors, including a low-fiber/high-fat diet, cesarean delivery, antiseptic agents, lack of breastfeeding, and drugs can induce gut microbiome dysbiosis, and have been associated with food allergy. New experimental tools and technologies have provided information regarding the role of metabolites generated from dietary nutrients and selected probiotic strains that could act on immune tolerance mechanisms. The mechanisms are multiple and still not completely defined. Increasing evidence has provided useful information on optimal bacterial species/strains, dosage, and timing for intervention. The increased knowledge of the crucial role played by nutrients and gut microbiota-derived metabolites is opening the way to a post-biotic approach in the stimulation of immune tolerance through epigenetic regulation. This review focused on the potential role of gut microbiome as the target for innovative strategies against food allergy
Nutraceuticals in thyroidology: A review of in vitro, and in vivo animal studies
Nutraceuticals are defined as a food, or parts of a food, that provide medical or health benefits, including the prevention of different pathological conditions, and thyroid diseases, or the treatment of them. Nutraceuticals have a place in complementary medicines, being positioned in an area among food, food supplements, and pharmaceuticals. The market of certain nutraceuticals such as thyroid supplements has been growing in the last years. In addition, iodine is a fundamental micronutrient for thyroid function, but also other dietary components can have a key role in clinical thyroidology. Here, we have summarized the in vitro, and in vivo animal studies present in literature, focusing on the commonest nutraceuticals generally encountered in the clinical practice (such as carnitine, flavonoids, melatonin, omega-3, resveratrol, selenium, vitamins, zinc, and inositol), highlighting conflicting results. These experimental studies are expected to improve clinicians’ knowledge about the main supplements being used, in order to clarify the potential risks or side effects and support patients in their use
Light-induced rotation of dye-doped liquid crystal droplets
We investigate both theoretically and experimentally the rotational dynamics
of micrometric droplets of dye-doped and pure liquid crystal induced by
circularly and elliptically polarized laser light. The droplets are dispersed
in water and trapped in the focus of the laser beam. Since the optical torque
acting on the molecular director is known to be strongly enhanced in
light-absorbing dye-doped materials, the question arises whether a similar
enhancement takes place also for the overall optical torque acting on the whole
droplets. We searched for such enhancement by measuring and comparing the
rotation speed of dye-doped droplets induced by a laser beam having a
wavelength either inside or outside the dye absorption band, and also comparing
it with the rotation of pure liquid crystal droplets. No enhancement was found,
confirming that photoinduced dye effects are only associated with an internal
exchange of angular momentum between orientational and translational degrees of
freedom of matter. Our result provides also the first direct experimental proof
of the existence of a photoinduced stress tensor in the illuminated dye-doped
liquid crystal. Finally, peculiar photoinduced dynamical effects are predicted
to occur in droplets in which the molecular director is not rigidly locked to
the flow, but so far they could not be observed
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