10,055 research outputs found
AN EXAMINATION OF THE TREND IN INDUSTRIAL DISPERSION IN OKLAHOMA FROM 1963 THROUGH 1974
Industrial Organization,
J/psi dissociation by light mesons in an extended Nambu Jona-Lasinio model
An alternative model for the dissociation of the J/psi is proposed. Chiral
symmetry is properly implemented. Abnormal parity interactions and mesonic form
factors naturally arise from the underlying quark sub-structure. Analytic
confinement for the light quarks is generated by appropriately chosen the quark
interaction kernels. Dissociation cross sections of the J/psi by either a pion
or a rho meson are then evaluated and discussed.Comment: 24 pages, 13 figures, final versio
Baryonic contributions to the dilepton spectra in relativistic heavy ion collisions
We investigate the baryonic contributions to the dilepton yield in high
energy heavy ion collisions within the context of a transport model. The
relative contribution of the baryonic and mesonic sources are examined. It is
observed that most dominant among the baryonic channels is the decay of
N*(1520) and mostly confined in the region below the rho peak. In a transport
theory implementation we find the baryonic contribution to the lepton pair
yield to be small.Comment: 11 pages, 8 figure
Socially stable matchings in the hospitals / residents problem
In the Hospitals/Residents (HR) problem, agents are partitioned into hospitals and residents. Each agent wishes to be matched to an agent in the other set and has a strict preference over these potential matches. A matching is stable if there are no blocking pairs, i.e., no pair of agents that prefer each other to their assigned matches. Such a situation is undesirable as it could lead to a deviation in which the blocking pair form a private arrangement outside the matching. This however assumes that the blocking pair have social ties or communication channels to facilitate the deviation. Relaxing the stability definition to take account of the potential lack of social ties between agents can yield larger stable matchings.
In this paper, we define the Hospitals/Residents problem under Social Stability (HRSS) which takes into account social ties between agents by introducing a social network graph to the HR problem. Edges in the social network graph correspond to resident-hospital pairs in the HR instance that know one another. Pairs that do not have corresponding edges in the social network graph can belong to a matching M but they can never block M. Relative to a relaxed stability definition for HRSS, called social stability, we show that socially stable matchings can have different sizes and the problem of finding a maximum socially stable matching is NP-hard, though approximable within 3/2. Furthermore we give polynomial time algorithms for three special cases of the problem
Cross-sectional associations between personality traits and device-based measures of step count and sedentary behaviour in older age: the Lothian birth cohort 1936
BACKGROUND: While the associations between personality traits and self-reported physical activity are well replicated, few studies have examined the associations between personality and device-based measures of both physical activity and sedentary behaviour. Low levels of physical activity and high levels of sedentary behaviour are known risk factors for poorer health outcomes in older age. METHODS: We used device-based measures of physical activity and sedentary behaviour recorded over 7 days in 271 79-year-old participants of the Lothian Birth Cohort 1936. Linear regression models were used to assess whether personality traits were cross-sectionally associated with step count, sedentary time, and the number of sit-to-stand transitions. Personality traits were entered one at a time, and all-together, controlling for age and sex in Model 1 and additionally for BMI and limiting long-term illness in Model 2. RESULTS: None of the associations between personality traits and measures of physical activity and sedentary behaviours remained significant after controlling for multiple-comparisons using the False Discovery Rate test (all ps > .07). CONCLUSIONS: We found no evidence that personality traits are associated with device-based measures of physical activity or sedentary behaviour in older age. More studies are needed to replicate and examine the nature of these relationships
Stable schedule matching under revealed preference
Baiou and Balinski (Math. Oper. Res., 27 (2002) 485) studied schedule matching where one determines the partnerships that form and how much time they spend together, under the assumption that each agent has a ranking on all potential partners. Here we study schedule matching under more general preferences that extend the substitutable preferences in Roth (Econometrica 52 (1984) 47) by an extension of the revealed preference approach in Alkan (Econom. Theory 19 (2002) 737). We give a generalization of the GaleShapley algorithm and show that some familiar properties of ordinary stable matchings continue to hold. Our main result is that, when preferences satisfy an additional property called size monotonicity, stable matchings are a lattice under the joint preferences of all agents on each side and have other interesting structural properties
Properties of the phi meson at high temperatures and densities
We calculate the spectral density of the phi meson in a hot bath of nucleons
and pions using a general formalism relating self-energy to the forward
scattering amplitude (FSA). In order to describe the low energy FSA, we use
experimental data along with a background term. For the high energy FSA, a
Regge parameterization is employed. We verify the resulting FSA using
dispersion techniques. We find that the position of the peak of the spectral
density is slightly shifted from its vacuum position and that its width is
considerably increased. The width of the spectral density at a temperature of
150 MeV and at normal nuclear density is more than 90 MeV.Comment: 4 pages, 5 figures, Poster presented at Quark Matter 200
Clinical correlates of tobacco smoking in OCD: A UK, case-controlled, exploratory analysis
Background:
Obsessive-compulsive disorder (OCD) is a biologically heterogeneous neuropsychiatric disorder. It is associated with impulsive as well as compulsive neurocognitive mechanisms. Cigarette smoking is common among most psychiatric patients; however, OCD patients are thought to show reduced rates. OCD smokers may thus represent a relatively uncommon OCD subtype, characterised by increased impulsivity. In this study, we aim to establish the prevalence of smoking in a large, well-defined OCD cohort. We investigate whether smokers with OCD differ from non-smokers with OCD on clinical measures of behavioural impulsivity and domains of personality and temperament, including reward-dependence and novelty-seeking.
Method:
183 of 200 outpatients with DSM-IV OCD were interviewed to determine smoking status. A sub-sample of 10 smokers was compared with 10 non-smokers, pair wise matched for age and gender. Patients were assessed for DSM co-morbidity, symptom profile, OCD severity, behavioural impulsivity and personality dimensions.
Results:
Only 10 individuals (5.46%; five males) were smokers. Compared to OCD non-smokers, OCD smokers scored significantly higher on the Barratt Impulsiveness Scale (p < 0.001). They also scored significantly higher on TCI measures of novelty seeking (p < 0.001) and reward dependence (p < 0.001) and significantly lower on measures of harm avoidance (p < 0.001).
Conclusions:
Tobacco smoking is rare in OCD. Significantly higher levels of behavioural impulsivity and temperamental factors associated with reward driven impulsivity are seen in OCD smokers compared to non-smokers. Tobacco smoking may indicate a possible source of neurocognitive heterogeneity in OCD
Low mass dimuons within a hybrid approach
We analyse dilepton emission from hot and dense hadronic matter using a
hybrid approach based on the Ultrarelativistic Quantum Molecular Dynamics
(UrQMD) transport model with an intermediate hydrodynamic stage for the
description of heavy-ion collisions at relativistic energies. Focusing on the
enhancement with respect to the contribution from long-lived hadron decays
after freeze-out observed at the SPS in the low mass region of the dilepton
spectra (often referred to as "the excess"), the relative importance of the
emission from the equilibrium and the non-equilibrium stages is discussed.Comment: Proceedings of Hot Quarks 2010, 21-26 June 2010 Las Londe Les Maures;
v2: Corrected typos and added a commen
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