6,951 research outputs found

    Resurrecting Minimal Yukawa Sector of SUSY SO(10)

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    Supersymmetric SO(10)SO(10) models with Yukawa coupling matrices involving only a 10H10_H and a 126H\overline{126}_H of Higgs fields can lead to a predictive and consistent scenario for fermion masses and mixings, including the neutrino sector. However, when coupled minimally to a symmetry breaking sector that includes a 210H210_H and a 126H126_H, these models lead either to an unacceptably small neutrino mass scale, or to non-perturbative values of the gauge couplings. Here we show that with the addition of a 54H54_H to the symmetry breaking sector, the successful predictions of these models for fermion masses and mixings can be maintained. The 54H54_H enables a reduction of the BLB-L symmetry breaking scale to an intermediate value of order 101210^{12} GeV, consistent with the observed neutrino mass spectrum, while preserving perturbative gauge coupling unification. We obtain an excellent fit to all fermion masses and mixings in this framework. We analyze carefully the prediction of the model for CP violation in neutrino oscillations. Consistency with proton lifetime, however, requires a mini-split SUSY spectrum with the squarks and sleptons having masses of order 100 TeV, accompanied by TeV scale gauginos and Higgsinos. Such a spectrum may arise from pure gravity mediation, which would predict the partial lifetime for the decay pνK+p \rightarrow \overline{\nu} K^+ to be an order of magnitude above the current experimental limit.Comment: 29 pages, 3 figures, replacement to match the published versio

    "Measuring Capacity Utilization in OECD Countries: A Cointegration Method"

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    This paper derives measures of potential output and capacity utilization for a number of OECD countries, using a method based on the cointegration relation between output and the capital stock. The intuitive idea is that economic capacity (potential output) is the aspect of output that co-varies with the capital stock over the long run. We show that this notion can be derived from a simple model that allows for a changing capital-capacity ratio in response to partially exogenous, partially embodied, technical change. Our method provides a simple and general procedure for estimating capacity utilization. It also closely replicates a previously developed census-based measure of U.S. manufacturing capacity-utilization. Of particular interest is that our measures of capacity utilization are very different from those based on aggregate production functions, such as the ones provided by the IMF.

    Dependence of acoustic surface gravity on disc thickness for accreting astrophysical black holes

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    For axially symmetric accretion maintained in hydrostatic equilibrium along the vertical direction, we investigate how the characteristic features of the embedded acoustic geometry depends on the background Kerr metric, and how such dependence is governed by three different expressions of the thickness of the matter flow. We first obtain the location of the sonic points and stationary shock between the sonic points. We then linearly perturb the flow to obtain the corresponding metric elements of the acoustic space-time. We thus construct the causal structure to establish that the sonic points and the shocks are actually the analogue black hole type and white hole type horizons, respectively. We finally compute the value of the acoustic surface gravity as a function of the spin angular momentum of the rotating black hole for three different flow thicknesses considered in the present work. We find that for some flow models, the intrinsic acoustic geometry, although in principle may be extended up to the outer gravitational horizon of the astrophysical black hole, cannot be constructed beyond a certain truncation radius as imposed by the expressions of the thickness function of the corresponding flow.Comment: 22 pages, 9 figure

    Pituitary-adrenal axis in Prader Willi syndrome

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    Purpose: Prader Willi syndrome (PWS) is a rare genetic condition that has concurrent endocrinological insufficiencies. The presence of growth hormone deficiency has been well documented, but adrenal insufficiency (AI) is not widely reported. A review was conducted to investigate its prevalence and relevance in PWS in both adults and children. Methodology: A literature review was performed with the search terms “Prader-Willi syndrome” and “adrenal insufficiency”. Results: The review found studies disagree on the prevalence and method of investigation of AI in PWS. Case studies demonstrate that patients with PWS are at risk of premature death, often secondary to respiratory infections. The possibility that this may be the result of the inability to mount an effective cortisol response has been studied, with some evidence confirming AI in PWS patients. Most reports agreed AI is present in PWS, however, Farholt et al. showed no HPA axis dysfunction in adults, suggesting that perhaps it is rare in adults, and children should be the focus of further studies. Conclusion: AI is present in some patients with PWS. Further research is required to ensure optimal treatment can be implemented and to prevent premature deaths related to adrenal insufficiency. Clinicians should have a low threshold for testing the adrenal axis and considering treatment for adrenal insufficiency in PWS patients

    Cue-centric model of the fireground incident commander's decision making process

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    Pattern recognition based models propose that in highly routine situations, the FireGround Incident Commanders (FGC) make decisions using experiences of the past similar incidents (Klein et al, 1986), which are stored in memory as schemas (Klein et al, 2006). Due to the nonsystematic development of schemas that guide pattern recognition (Beach & Mitchell, 1978) and the biases attached with pattern recognition (Tversky & Kahnmen, 1974), this approach is least favorable candidate for decision making in nonroutine situations. The nonroutine situations are characterized by: failure to clearly recognize relevant past episodes (Bousfield & Sedgewick, 1944), deliberate avoiding of recalling the past episodes (Jacoby et al, 1989) or time constraint and ambiguity of available information for decision making. This research proposes that in nonroutine situations, the FGCs rely on thorough search and assessment of diagnostic, relevant, and important cues. Therefore, one aim of this research is to propose a model of the FGCs' decision making process for nonroutine situations; the model will base on the use of cues rather than the pattern recognition approach. This research also aims to provide a robust and coherent definition of the FGC’s decision making process and will subsequently specify the structure and the underlying phases of it. The context of the research is the decisions made by the FGCs during large fires, involving at least 5 fire appliances. 20 FGCs from 2 of the UK’s large firebrigades with at least 7 years of experience in command position participated in a fieldwork carried over a period of 1 year. For the data collection, multiple case studies in the form of critical incident reports are obtained from the participants. Each critical incident is explored further through semi-structured interviews. For the data analysis, theoretical or deductive thematic approach and process reconstruction method (Nutt, 1983) are used. Results indicate that the current definition of the term ‘FGC’s decision making process’ is incomplete. The definition of the FGC’s decision making process proposed in this research now, recognizes that each process of selection and evaluation of a course of action to solve a problem (Klein et al, 1986) is preceded by a process of identification of a problem. This definition commensurate with the widely acceptable definition of decision making process proposed in Nutt (1984). This research also found that the FGCs make decisions in 2 cyclic and distinguishable phases, which are the ‘problem recognition’ phase, and the ‘solution generation’ phase. Finally, a cue-centric model of the FGC's decision making process is proposed. The model showed that in nonroutine situations, when pattern recognition fails to guide the decision making process, the FGCs develop a mental model of a situation through thorough search and assessment of the valuable cues based on their diagnosticity, importance and relevance. The mental model assists in identifying problems and selecting a course of action to solve that problem. This research fulfills the need of developing descriptive models for clarifying issues arising in the areas of training, selection, and in developing decision support systems (Klein et al, 1986)

    ESTIMATING THE OPPORTUNITY COST OF RECREATION TIME IN AN INTEGRABLE 2-CONSTRAINT COUNT DEMAND MODEL

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    How researchers treat the opportunity cost of time substantially influences recreation demand parameter and welfare estimates. This paper presents a utility-theoretic and implementable approach, estimating the shadow value of time jointly with recreation demands for coastal activities, using a generalization of the semilog demand system in a two-constraint model.Consumer/Household Economics, Demand and Price Analysis,
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