82,399 research outputs found

    Neutrino parameters and the N2N_2-dominated scenario of leptogenesis

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    We briefly review the main aspects of leptogenesis, describing both the unflavoured and the flavoured versions of the N2N_2-dominated scenario. A study of the success rates of both classes of models has been carried out. We comment on these results and discuss corrective effects to this simplest scenario. Focusing on the flavoured case, we consider the conditions required by strong thermal leptogenesis, where the final asymmetry is fully independent of the initial conditions. Barring strong cancellations in the seesaw formula and in the flavoured decay parameters, we show that strong thermal leptogenesis favours a lightest neutrino mass m_1\gtrsim10\,\mbox{meV} for normal ordering (NO) and m_1\gtrsim 3\,\mbox{meV} for inverted ordering (IO). Finally, we briefly comment on the power of absolute neutrino mass scale experiments to either support or severely corner strong thermal leptogenesis.Comment: Contribution to the Proceedings of the NuPhys2013 Conference: Prospects in Neutrino Physics, 19-20 December 2013, IOP, Londo

    Strong thermal leptogenesis and the absolute neutrino mass scale

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    We show that successful strong thermal leptogenesis, where the final asymmetry is independent of the initial conditions and in particular a large pre-existing asymmetry is efficiently washed-out, favours values of the lightest neutrino mass m110meVm_1 \gtrsim 10\,{\rm meV} for normal ordering (NO) and m13meVm_1 \gtrsim 3\,{\rm meV} for inverted ordering (IO) for models with orthogonal matrix entries respecting Ωij22|\Omega_{ij}^2| \lesssim 2. . We show analytically why lower values of m1m_1 require a high level of fine tuning in the seesaw formula and/or in the flavoured decay parameters (in the electronic for NO, in the muonic for IO). We also show how this constraint exists thanks to the measured values of the neutrino mixing angles and can be tighten by a future determination of the Dirac phase. Our analysis also allows to place more stringent constraint for a specific model or class of models, such as SO(10)SO(10)-inspired models, and shows that some models cannot realise strong thermal leptogenesis for any value of m1m_1. A scatter plot analysis fully supports the analytical results. We also briefly discuss the interplay with absolute neutrino mass scale experiments concluding that they will be able in the coming years to either corner strong thermal leptogenesis or find positive signals pointing to a non-vanishing m1m_1. Since the constraint is much stronger for NO than for IO, it is very important that new data from planned neutrino oscillation experiments will be able to solve the ambiguity.Comment: 22 pages; 7 figures; v2: matches JCAP versio

    Shutters, Boxes, But No Paradoxes: Time Symmetry Puzzles in Quantum Theory

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    The ``N-Box Experiment'' is a much-discussed thought experiment in quantum mechanics. It is claimed by some authors that a single particle prepared in a superposition of N+1 box locations and which is subject to a final ``post-selection'' measurement corresponding to a different superposition can be said to have occupied ``with certainty'' N boxes during the intervening time. However, others have argued that under closer inspection, this surprising claim fails to hold. Aharonov and Vaidman have continued their advocacy of the claim in question by proposing a variation on the N-box experiment, in which the boxes are replaced by shutters and the pre- and post-selected particle is entangled with a photon. These authors argue that the resulting ``N-shutter experiment'' strengthens their original claim regarding the N-box experiment. It is argued in this paper that the apparently surprising features of this variation are no more robust than those of the N-box experiment and that it is not accurate to say that the particle is ``with certainty'' in all N shutters at any given time.Comment: Presentation improved; to appear in International Studies in Philosophy of Scienc

    Social capital and rural innovation process. The evaluation of the measure 124 \u201cCooperation for Development of New Products, Processes and Technologies in the Agriculture, Food and Forestry Sector\u201d in the Umbria Region (Italy)

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    The most recent theories on innovation point out the role of social networks, demonstrating how knowledge is intertwined with network communities and social capital represents an essential factor to comprehend innovation. The social network dimension of the innovation process is also acknowledged in the actual definition of an agricultural innovation system (AIS). This study attempts to assess the role played by social capital in agricultural innovation projects co-financed by the Measure 124 of the Rural Development Program (2007-2013) of the Umbria Region (Italy), based on the analysis of 5 evaluation criteria (relevance, innovation, effectiveness, sustainability, and social capital) in relation to 8 selected projects. The obtained results confirm the validity of the proposed methodology both for the purpose of internal monitoring of the project and for the assessment of the measure on the basis of tangible and intangible factors, such as social capital

    State-of-the-art generators for top physics

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    We describe the status and the availability of tools to simulate processes at hadron colliders where top quarks are present

    Parametric investigation of single-expansion-ramp nozzles at Mach numbers from 0.60 to 1.20

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    An investigation was conducted in the Langley 16-Foot Transonic Tunnel to determine the effects of varying six nozzle geometric parameters on the internal and aeropropulsive performance characteristics of single-expansion-ramp nozzles. This investigation was conducted at Mach numbers from 0.60 to 1.20, nozzle pressure ratios from 1.5 to 12, and angles of attack of 0 deg +/- 6 deg. Maximum aeropropulsive performance at a particular Mach number was highly dependent on the operating nozzle pressure ratio. For example, as the nozzle upper ramp length or angle increased, some nozzles had higher performance at a Mach number of 0.90 because of the nozzle design pressure was the same as the operating pressure ratio. Thus, selection of the various nozzle geometric parameters should be based on the mission requirements of the aircraft. A combination of large upper ramp and large lower flap boattail angles produced greater nozzle drag coefficients at Mach number greater than 0.80, primarily from shock-induced separation on the lower flap of the nozzle. A static conditions, the convergent nozzle had high and nearly constant values of resultant thrust ratio over the entire range of nozzle pressure ratios tested. However, these nozzles had much lower aeropropulsive performance than the convergent-divergent nozzle at Mach number greater than 0.60

    On the Computational Complexity of Non-dictatorial Aggregation

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    We investigate when non-dictatorial aggregation is possible from an algorithmic perspective, where non-dictatorial aggregation means that the votes cast by the members of a society can be aggregated in such a way that the collective outcome is not simply the choices made by a single member of the society. We consider the setting in which the members of a society take a position on a fixed collection of issues, where for each issue several different alternatives are possible, but the combination of choices must belong to a given set XX of allowable voting patterns. Such a set XX is called a possibility domain if there is an aggregator that is non-dictatorial, operates separately on each issue, and returns values among those cast by the society on each issue. We design a polynomial-time algorithm that decides, given a set XX of voting patterns, whether or not XX is a possibility domain. Furthermore, if XX is a possibility domain, then the algorithm constructs in polynomial time such a non-dictatorial aggregator for XX. We then show that the question of whether a Boolean domain XX is a possibility domain is in NLOGSPACE. We also design a polynomial-time algorithm that decides whether XX is a uniform possibility domain, that is, whether XX admits an aggregator that is non-dictatorial even when restricted to any two positions for each issue. As in the case of possibility domains, the algorithm also constructs in polynomial time a uniform non-dictatorial aggregator, if one exists. Then, we turn our attention to the case where XX is given implicitly, either as the set of assignments satisfying a propositional formula, or as a set of consistent evaluations of an sequence of propositional formulas. In both cases, we provide bounds to the complexity of deciding if XX is a (uniform) possibility domain.Comment: 21 page

    Prognostic factors of survival in patients treated with nab-paclitaxel plus gemcitabine regimen for advanced or metastatic pancreatic cancer: A single institutional experience.

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    The objectives of this study were to evaluate the effectiveness of nab-paclitaxel plus gemcitabine (NAB-P/GEM) regimen in an unselected population of patients with advanced inoperable or metastatic pancreatic cancer (PC), and to identify the prognostic factors influencing overall survival (OS). EXPERIMENTAL DESIGN: Patients with age < 85 years, ECOG-performance status (PS) < 3, and adequate renal, hepatic and hematologic function were eligible. NAB-P (125 mg/m2) and GEM (1000 mg/m2) day 1,8,15 every 4 weeks were employed for 3-6 cycles or until highest response. RESULTS: Overall, 147 cycles (median 4, range 1-11 cycles) were administered on thirty-seven consecutive patients (median 66 years old, range 40-82) treated. The median overall progression-free survival and OS were 6.2 and 9.2 months, respectively. The G 3-4 dose-limiting toxicity were neutropenia (20.7%), severe anemia (17.2%), and cardiovascular toxicity (10.3%). PS, number of cycles, baseline CA 19-9 and LDH serum levels, were found to be significantly related to OS. The multivariate analysis showed that both number of cycles (HR = 9.14, 95% CI 1.84-45.50, p = 0.001) and PS (HR = 13.18, 95% CI 2.73-63.71, p = 0.001) were independently associated with OS. CONCLUSION: NAB-P/GEM regimen should be used in all patients with advanced or metastatic PC, with the exception of those with serious contraindications to chemotherapy, such as severe renal or hepatic impairment or major cardiovascular diseases
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