517 research outputs found
Singularly Perturbed Monotone Systems and an Application to Double Phosphorylation Cycles
The theory of monotone dynamical systems has been found very useful in the
modeling of some gene, protein, and signaling networks. In monotone systems,
every net feedback loop is positive. On the other hand, negative feedback loops
are important features of many systems, since they are required for adaptation
and precision. This paper shows that, provided that these negative loops act at
a comparatively fast time scale, the main dynamical property of (strongly)
monotone systems, convergence to steady states, is still valid. An application
is worked out to a double-phosphorylation ``futile cycle'' motif which plays a
central role in eukaryotic cell signaling.Comment: 21 pages, 3 figures, corrected typos, references remove
Self-compassion and suicide risk in veterans : when the going gets tough, do the tough benefit more from self-kindness?
Objectives: Veterans are at particular risk for suicide due to psychopathological, emotional, and interpersonal risk factors. However, the presence of individual-level protective factors, such as self-compassion, may reduce risk, becoming more salient at increasing levels of distress and psychopathology, per theory. We examined the relation between self-compassion and suicide risk, and the moderating effects of depression, PTSD symptoms, anger, shame, and thwarted interpersonal needs.
Methods: Our sample of United States veterans (n=541) in our cross-sectional study were mostly male (69.1%) with an average age of 49.90 (SD=16.78), who completed online self-report measures: Suicidal Behaviors Questionnaire-Revised, Multidimensional Health Profile-Psychosocial Functioning Screening Tool, PTSD Checklist-Military Version, Differential Emotions Scale-IV, and the Interpersonal Needs Questionnaire.
Results: The linkage between self-compassion and suicidal behavior in our veteran sample was moderated by distress-evoking risk factors, including depression, anger, shame, and thwarted interpersonal needs, such that, as level of risk severity increases, the inverse association between self-compassion and suicidal behavior is strengthened.
Conclusions: Our findings highlight an emergent protective process that may prevent suicide in times of distress. Therapeutically bolstering the ability for self-compassion may provide a proactive coping strategy that can be brought to bear in times of crisis, reducing suicide risk for veterans
Evidence for hadronic deconfinement in -p collisions at 1.8 TeV
We have measured deconfined hadronic volumes, fm,
produced by a one dimensional (1D) expansion. These volumes are directly
proportional to the charged particle pseudorapidity densities . The hadronization temperature is (syst)
MeV. Using Bjorken's 1D model,the hadronization energy density is (stat) GeV/fm corresponding to an excitation of (stat) quark-gluon degrees of freedom.Comment: 15 pages, 3 figures, 2 table
The influence of surface hardness on the fretting wear of steel pairs: its role in debris retention in the contact
The influence of specimen hardness (between 275 kgf mmâ2 and 835 kgf mmâ2) in an AISI Type O1 steel-on-steel fretting contact was examined. In equal-hardness pairs, a variation in the wear volume of around 20% across the range of hardnesses examined was observed. However, in pairs where the two specimens in the couple had different hardnesses, a critical hardness differential threshold existed, above which the wear was predominantly associated with the harder specimen (with debris embedment on the softer specimen surface). This retention of debris provides protection of that surface from further wear and also results in accelerated wear of the harder counterface due to abrasion by the oxide debris bed which has built up on the opposing specimen
On the Low Surface Magnetic Field Structure of Quark Stars
Following some of the recent articles on hole super-conductivity and related
phenomena by Hirsch \cite{H1,H2,H3}, a simple model is proposed to explain the
observed low surface magnetic field of the expected quark stars. It is argued
that the diamagnetic moments of the electrons circulating in the electro-sphere
induce a magnetic field, which forces the existing quark star magnetic flux
density to become dilute. We have also analysed the instability of
normal-superconducting interface due to excess accumulation of magnetic flux
lines, assuming an extremely slow growth of superconducting phase through a
first order bubble nucleation type transition.Comment: 24 pages REVTEX, one .eps figure, psfig.sty is include
Psychometric assessment of the short-form Child Perceptions Questionnaire: an international collaborative study.
OBJECTIVE: To examine the factor structure and other psychometric characteristics of the most commonly used child oral-health-related quality-of-life (OHRQoL) measure (the 16-item short-form CPQ11-14 ) in a large number of children (N = 5804) from different settings and who had a range of caries experience and associated impacts. METHODS: Secondary data analyses used subnational epidemiological samples of 11- to 14-year-olds in Australia (N = 372), New Zealand (three samples: 352, 202, 429), Brunei (423), Cambodia (244), Hong Kong (542), Malaysia (439), Thailand (220, 325), England (88, 374), Germany (1055), Mexico (335) and Brazil (404). Confirmatory factor analysis (CFA) was used to examine the factor structure of the CPQ11-14 across the combined sample and within four regions (Australia/NZ, Asia, UK/Europe and Latin America). Item impact and internal reliability analysis were also conducted. RESULTS: Caries experience varied, with mean DMFT scores ranging from 0.5 in the Malaysian sample to 3.4 in one New Zealand sample. Even more variation was noted in the proportion reporting only fair or poor oral health; this was highest in the Cambodian and Mexican samples and lowest in the German sample and one New Zealand sample. One in 10 reported that their oral health had a marked impact on their life overall. The CFA across all samples revealed two factors with eigenvalues greater than 1. The first involved all items in the oral symptoms and functional limitations subscales; the second involved all emotional well-being and social well-being items. The first was designated the 'symptoms/function' subscale, and the second was designated the 'well-being' subscale. Cronbach's alpha scores were 0.72 and 0.84, respectively. The symptoms/function subscale contained more of the items with greater impact, with the item 'Food stuck in between your teeth' having greatest impact; in the well-being subscale, the 'Felt shy or embarrassed' item had the greatest impact. Repeating the analyses by world region gave similar findings. CONCLUSION: The CPQ11-14 performed well cross-sectionally in the largest analysis of the scale in the literature to date, with robust and mostly consistent psychometric characteristics, albeit with two underlying factors (rather than the originally hypothesized four-factor structure). It appears to be a sound, robust measure which should be useful for research, practice and policy
First- principle calculations of magnetic interactions in correlated systems
We present a novel approach to calculate the effective exchange interaction
parameters based on the realistic electronic structure of correlated magnetic
crystals in local approach with the frequency dependent self energy. The analog
of ``local force theorem'' in the density functional theory is proven for
highly correlated systems. The expressions for effective exchange parameters,
Dzialoshinskii- Moriya interaction, and magnetic anisotropy are derived. The
first-principle calculations of magnetic excitation spectrum for ferromagnetic
iron, with the local correlation effects from the numerically exact QMC-scheme
is presented.Comment: 17 pages, 3 Postscript figure
Characterization of halogen-bridged binuclear metal complexes as hybridized two-band materials
We study the electronic structure of halogen-bridged binuclear metal (MMX)
complexes with a two-band Peierls-Hubbard model. Based on a symmetry argument,
various density-wave states are derived and characterized. The ground-state
phase diagram is drawn within the Hartree-Fock approximation, while the thermal
behavior is investigated using a quantum Monte Carlo method. All the
calculations conclude that a typical MMX compound Pt_2(CH_3CS_2)_4I should
indeed be regarded as a d-p-hybridized two-band material, where the oxidation
of the halogen ions must be observed even in the ground state, whereas another
MMX family (NH_4)_4[Pt_2(P_2O_5H_2)_4X] may be treated as single-band
materials.Comment: 16 pages, 11 figures embedded, to be published in Phys. Rev.
Fibromyalgia impact and depressive symptoms: Can perceiving a silver lining make a difference?
Individuals with fibromyalgia are at greater risk for depressive symptoms than the general population, and this may be partially attributable to physical symptoms that impair dayâtoâday functioning. However, individualâlevel protective characteristics may buffer risk for psychopathology. For instance, the ability to perceive a âsilver liningâ in oneâs illness may be related to better mental and physical health. We examined perceived silver lining as a potential moderator of the relation between fibromyalgia impact and depressive symptoms. Our sample of persons with fibromyalgia (N = 401) completed selfâreport measures including the Fibromyalgia Impact QuestionnaireâRevised, Depression Anxiety Stress Scales, and the Silver Lining Questionnaire. Moderation analyses covaried age, sex, and ethnicity. Supporting hypotheses, increasing impact of disease was related to greater depressive symptoms, and perceptions of a silver lining attenuated that association. Despite the linkage between impairment and depressive symptoms, identifying positive aspects or outcomes of illness may reduce risk for psychopathology. Therapeutically promoting perception of a silver lining, perhaps via signature strengths exercises or a blessings journal, and encouraging cognitive reframing of the illness experience, perhaps via Motivational Interviewing or Cognitive Behavioral Therapy, may reduce depressive symptoms in persons with fibromyalgia
Status of a Supersymmetric Flavour Violating Solution to the Solar Neutrino Puzzle with Three Generations
We present a general study of a three neutrino flavour transition model based
on the supersymmetric interactions which violate R-parity. These interactions
induce flavour violating scattering reactions between solar matter and
neutrinos. The model does not contain any vacuum mass or mixing angle for the
first generation neutrino. Instead, the effective mixing in the first
generation is induced via the new interactions. The model provides a natural
interpretation of the atmospheric neutrino anomaly, and is consistent with
reactor experiments. We determine all R-parity violating couplings which can
contribute to the effective neutrino oscillations, and summarize the present
laboratory bounds. Independent of the specific nature of the (supersymmetric)
flavour violating model, the experimental data on the solar neutrino rates and
the recoil electron energy spectrum are inconsistent with the theoretical
predictions. The confidence level of the -analysis ranges between and . The incompatibility, is due to the new SNO
results, and excludes the present model. We conclude that a non-vanishing
vacuum mixing angle for the first generation neutrino is necessary in our
model. We expect this also to apply to the solutions based on other flavour
violating interactions having constraints of the same order of magnitude.Comment: 17 pages, Latex fil
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