Quark deconfinement in neutron star cores: The effects of spin-down

We study the role of spin-down in driving quark deconfinement in the high density core of isolated neutron stars. Assuming spin-down to be solely due to magnetic braking, we obtain typical timescales to quark deconfinement for neutron stars that are born with Keplerian frequencies. Employing different equations of state (EOS), we determine the minimum and maximum neutron star masses that will allow for deconfinement via spin-down only. We find that the time to reach deconfinement is strongly dependent on the magnetic field and that this time is least for EOS that support the largest minimum mass at zero spin, unless rotational effects on stellar structure are large. For a fiducial critical density of $5\rho_0$ for the transition to the quark phase ($\rho_0=2.5\times10^{14}$g/cm$^3$ is the saturation density of nuclear matter), we find that neutron stars lighter than $1.5M_{\odot}$ cannot reach a deconfined phase. Depending on the EOS, neutron stars of more than $1.5M_{\odot}$ can enter a quark phase only if they are spinning faster than about 3 milliseconds as observed now, whereas larger spin periods imply that they are either already quark stars or will never become one.Comment: 4 pages, 4 figures, submitted to ApJ

Structural brain complexity and cognitive decline in late life : A longitudinal study in the Aberdeen 1936 Birth Cohort

Copyright © 2014 Elsevier Inc. All rights reserved.Peer reviewedPostprin

Childhood intelligence and personality traits neuroticism and openness contributes to social mobility : A study in the Aberdeen 1936 Birth Cohort

Peer reviewedPostprin

Gifts at Work

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Family transitions and changes in drinking from adolescence through mid-life

AIMS: To examine how changes in social roles, particularly in the family, predict rises and falls in alcohol consumption from ages 16 to 50 years. DESIGN: Longitudinal data from the National Child Development Study. SETTING: The birth cohort includes 99% of British infants born in 1 week in 1958. Participants After initial assessment of 17,415 infants, the cohort was interviewed at ages 7, 11, 16, 23, 33, 42, 46, and 50. This study uses the six adolescent to adult waves (n = 7212 women, 7377 men). MEASUREMENTS: Alcohol use [i.e. quantity consumed in past week and heavy daily drinking), symptoms of problem drinking (i.e. Cut-down, Annoyed, Guilt, Eye-opener (CAGE)] and social roles (i.e. union formation, parenthood and employment). FINDINGS: Estimates from fixed-effects models demonstrate that alcohol use is lower when women reside with child(ren) under age 5, compared to occasions when they do not [estimate = -0.38, 95% confidence interval (CI) = -0.43, -0.32 for past week units; odds ratio (OR) = 0.47, CI = 0.36, 0.62 for heavy-daily drinking; OR = 0.66, CI = 0.50, 0.87 for CAGE symptoms]. Associations are similar for men (estimate = -0.29, CI = -0.36, -0.23; OR = 0.64, CI = 0.53, 0.77; OR = 0.69, CI = 0.51, 0.94, respectively). When women and men are married, working and residing with young child(ren), past week units (estimate = -0.51, CI = -0.61, -0.41 for women; estimate = -0.34, CI = -0.44, -0.25 for men), heavy-daily drinking (OR = 0.49, CI = 0.30, 0.79 for women; OR = 0.47, CI = 0.35, 0.64 for men) and CAGE (OR = 0.44, CI = 0.23, 0.83 for women; OR = 0.39, CI = 0.18, 0.82 for men) are lower compared to occasions when they are not in these roles. CONCLUSIONS: From late adolescence to mid-life, women and men in Britain are most at risk for higher levels of alcohol consumption and problem drinking when family roles are absent

Tau Aggregation Inhibitor Therapy : An Exploratory Phase 2 Study in Mild or Moderate Alzheimer's Disease

ACKNOWLEDGMENTS We thank patients and their caregivers for their participation in the study and are indebted to all the investigators involved in the study, particularly Drs. Douglas Fowlie and Donald Mowat for their helpful contributions to the clinical execution of the study in Scotland. We thank Sharon Eastwood, Parexel, for assistance in preparing initial drafts of the manuscript. We acknowledge constructive comments provided by Professors G. Wilcock and S. Gauthier on drafts of the article. CMW, CRH, and JMDS are officers of, and hold beneficial interests in, TauRx Therapeutics. RTS, PB, KK, and DJW are paid consultants to TauRx Therapeutics. The study was financed entirely by TauRx TherapeuticsPeer reviewedPublisher PD

A three stage model for the inner engine of GRBs: Prompt emission and early afterglow

We describe a model within the ``Quark-nova'' scenario to interpret the recent observations of early X-ray afterglows of long Gamma-Ray Bursts (GRB) with the Swift satellite. This is a three-stage model within the context of a core-collapse supernova. STAGE 1 is an accreting (proto-) neutron star leading to a possible delay between the core collapse and the GRB. STAGE 2 is accretion onto a quark-star, launching an ultrarelativistic jet generating the prompt GRB. This jet also creates the afterglow as the jet interacts with the surrounding medium creating an external shock. Slower shells ejected from the quark star (during accretion), can re-energize the external shock leading to a flatter segment in the X-ray afterglow. STAGE 3, which occurs only if the quark-star collapses to form a black-hole, consists of an accreting black-hole. The jet launched in this accretion process interacts with the preceding quark star jet, and could generate the flaring activity frequently seen in early X-ray afterglows. Alternatively, a STAGE 2b can occur in our model if the quark star does not collapse to a black hole. The quark star in this case can then spin down due to magnetic braking, and the spin down energy may lead to flattening in the X-ray afterglow as well. This model seems to account for both the energies and the timescales of GRBs, in addition to the newly discovered early X-ray afterglow features.Comment: 4 pages, to appear in the proceedings of the HEPRO conference, September 24-28, 2007, Dublin, Irelan