7,201 research outputs found
Resurrecting Minimal Yukawa Sector of SUSY SO(10)
Supersymmetric models with Yukawa coupling matrices involving only a
and a 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 and a , 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 to the symmetry
breaking sector, the successful predictions of these models for fermion masses
and mixings can be maintained. The enables a reduction of the
symmetry breaking scale to an intermediate value of order 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 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"
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.
Pituitary-adrenal axis in Prader Willi syndrome
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
Dependence of acoustic surface gravity on disc thickness for accreting astrophysical black holes
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
ESTIMATING THE OPPORTUNITY COST OF RECREATION TIME IN AN INTEGRABLE 2-CONSTRAINT COUNT DEMAND MODEL
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,
Cue-centric model of the fireground incident commander's decision making process
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)
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