A description of n-ary semigroups polynomial-derived from integral domains

We provide a complete classification of the n-ary semigroup structures defined by polynomial functions over infinite commutative integral domains with identity, thus generalizing G{\l}azek and Gleichgewicht's classification of the corresponding ternary semigroups

Gene expression time delays & Turing pattern formation systems

The incorporation of time delays can greatly affect the behaviour of partial differential equations and dynamical systems. In addition, there is evidence that time delays in gene expression due to transcription and translation play an important role in the dynamics of cellular systems. In this paper, we investigate the effects of incorporating gene expression time delays into a one-dimensional putative reaction diffusion pattern formation mechanism on both stationary domains and domains with spatially uniform exponential growth. While oscillatory behaviour is rare, we find that the time taken to initiate and stabilise patterns increases dramatically as the time delay is increased. In addition, we observe that on rapidly growing domains the time delay can induce a failure of the Turing instability which cannot be predicted by a naive linear analysis of the underlying equations about the homogeneous steady state. The dramatic lag in the induction of patterning, or even its complete absence on occasions, highlights the importance of considering explicit gene expression time delays in models for cellular reaction diffusion patterning

The influence of gene expression time delays on Gierer-Meinhardt pattern formation systems

There are numerous examples of morphogen gradients controlling long range signalling in developmental and cellular systems. The prospect of two such interacting morphogens instigating long range self-organisation in biological systems via a Turing bifurcation has been explored, postulated, or implicated in the context of numerous developmental processes. However, modelling investigations of cellular systems typically neglect the influence of gene expression on such dynamics, even though transcription and translation are observed to be important in morphogenetic systems. In particular, the influence of gene expression on a large class of Turing bifurcation models, namely those with pure kinetics such as the Gierer–Meinhardt system, is unexplored. Our investigations demonstrate that the behaviour of the Gierer–Meinhardt model profoundly changes on the inclusion of gene expression dynamics and is sensitive to the sub-cellular details of gene expression. Features such as concentration blow up, morphogen oscillations and radical sensitivities to the duration of gene expression are observed and, at best, severely restrict the possible parameter spaces for feasible biological behaviour. These results also indicate that the behaviour of Turing pattern formation systems on the inclusion of gene expression time delays may provide a means of distinguishing between possible forms of interaction kinetics. Finally, this study also emphasises that sub-cellular and gene expression dynamics should not be simply neglected in models of long range biological pattern formation via morphogens

Patterns of Mood and Personality Factors and Associations With STI/HIV-Related Drug and Sex Risk Among African American Male Inmates

Background: Research on the association between antisocial personality disorder (ASPD) with comorbid mental disorders and sexually transmitted infection (STI)/HIV risk among inmates is scant despite the high prevalence of psychopathology and of STI/HIV in this population. Methods: We used baseline data from Project DISRUPT, a cohort study conducted among incarcerated African American men (n = 207), to measure associations between ASPD and STI/HIV risk. We also conducted latent class analyses (LCAs) to identify subgroups defined by ASPD with comorbid stress, depression, and borderline personality disorder symptoms and measured associations between latent class membership and STI/HIV risk. Results: Approximately 15% had ASPD and 39% reported depression. Controlling for sociodemographics, stress, and depression, ASPD was independently associated with illicit [AOR = 3.23, 95% confidence interval (CI): 1.18–8.87] and injection drug use (AOR: 5.49, 95% CI: 1.23–24.42) but not with sexual risk. LCAs suggested that those at high risk of ASPD were likely to experience co-morbid mental disorders. ASPD comorbid with these disorders was linked to drug and sex risk. Conclusions: STI/HIV prevention for inmates should incorporate diagnosis and treatment of ASPD and comorbid disorders, and interventions to address ASPD-related factors (e.g., impulsivity) that drive STI/HIV risk

The Committed Intimate Partnerships of Incarcerated African-American Men: Implications for Sexual HIV Transmission Risk and Prevention Opportunities

Incarceration is thought to influence HIV transmission by disrupting partnerships that provide support and protect against sex risk-taking. Current correctional facility-based family-strengthening programs focus on marital partnerships, a minority of inmates’ partnerships. Research on the sex partnerships of incarcerated African-American men and the types of partnerships most likely to protect against HIV-related sex risk is limited. Improved understanding can inform expansion of correctional facility-based family-strengthening programs to a greater proportion of protective partnerships and HIV risk reduction programs to partnerships vulnerable to sex risk. Project DISRUPT is a cohort study of African-American men being released from prison in North Carolina who were in committed heterosexual partnerships at prison entry. Using baseline survey data (N = 189), we conducted latent class analysis (LCA) to identify subgroups of participants with distinct relationship profiles and measured associations between relationship characteristics and multiple partnerships of inmates and their partners in the six months before incarceration. LCA indicated a two-class solution, with relationships distinguished by satisfaction/stability (satisfied/stable class: 58.0%; dissatisfied/unstable class: 42.0%); each class had comparable relationship length and levels of marriage and cohabitation. Dissatisfied/unstable relationships were associated with multiple partnerships among participants (AOR 2.93, 95% CI 1.50, 5.72) and partners (AOR 4.95, 95% CI 1.68, 14.58). Satisfaction indicators—versus length, marriage, or cohabitation—were the strongest independent correlates of inmates’ and partners’ multiple partnerships. Pre-incarceration economic deprivation, mental disorder symptoms, substance use, and violence in relationships were associated with dissatisfaction/instability. Prison-based programs designed to maintain healthy partnerships, strengthen relationship skills, and reduce HIV risk-taking and violence in relationships are warranted and should be targeted to both marital and nonmarital partnerships. Programming also should address the poverty, mental illness, and substance use factors that threaten relationship satisfaction/stability and increase HIV risk

Measurement of the ratios of the Z/G* + >= n jet production cross sections to the total inclusive Z/G* cross section in ppbar collisions at sqrt(s) = 1.96 TeV

We present a study of events with Z bosons and jets produced at the Fermilab Tevatron Collider in ppbar collisions at a center of mass energy of 1.96 TeV. The data sample consists of nearly 14,000 Z/G* -> e+e- candidates corresponding to the integrated luminosity of 0.4 fb-1 collected using the D0 detector. Ratios of the Z/G* + >= n jet cross sections to the total inclusive Z/G* cross section have been measured for n = 1 to 4 jet events. Our measurements are found to be in good agreement with a next-to-leading order QCD calculation and with a tree-level QCD prediction with parton shower simulation and hadronization.Comment: 7 pages, 2 figures, slightly modified, submitted to Phys. Lett.

Measurement of the Isolated Photon Cross Section in p-pbar Collisions at sqrt{s}=1.96 TeV

The cross section for the inclusive production of isolated photons has been measured in p anti-p collisions at sqrt{s}=1.96 TeV with the D0 detector at the Fermilab Tevatron Collider. The photons span transverse momenta 23 to 300 GeV and have pseudorapidity |eta|<0.9. The cross section is compared with the results from two next-to-leading order perturbative QCD calculations. The theoretical predictions agree with the measurement within uncertainties.Comment: 7 pages, 5 figures, submitted to Phys.Lett.

Measurement of the polarisation of W bosons produced with large transverse momentum in pp collisions at sqrt(s) = 7 TeV with the ATLAS experiment

This paper describes an analysis of the angular distribution of W->enu and W->munu decays, using data from pp collisions at sqrt(s) = 7 TeV recorded with the ATLAS detector at the LHC in 2010, corresponding to an integrated luminosity of about 35 pb^-1. Using the decay lepton transverse momentum and the missing transverse energy, the W decay angular distribution projected onto the transverse plane is obtained and analysed in terms of helicity fractions f0, fL and fR over two ranges of W transverse momentum (ptw): 35 < ptw < 50 GeV and ptw > 50 GeV. Good agreement is found with theoretical predictions. For ptw > 50 GeV, the values of f0 and fL-fR, averaged over charge and lepton flavour, are measured to be : f0 = 0.127 +/- 0.030 +/- 0.108 and fL-fR = 0.252 +/- 0.017 +/- 0.030, where the first uncertainties are statistical, and the second include all systematic effects.Comment: 19 pages plus author list (34 pages total), 9 figures, 11 tables, revised author list, matches European Journal of Physics C versio

Observation of a new chi_b state in radiative transitions to Upsilon(1S) and Upsilon(2S) at ATLAS

The chi_b(nP) quarkonium states are produced in proton-proton collisions at the Large Hadron Collider (LHC) at sqrt(s) = 7 TeV and recorded by the ATLAS detector. Using a data sample corresponding to an integrated luminosity of 4.4 fb^-1, these states are reconstructed through their radiative decays to Upsilon(1S,2S) with Upsilon->mu+mu-. In addition to the mass peaks corresponding to the decay modes chi_b(1P,2P)->Upsilon(1S)gamma, a new structure centered at a mass of 10.530+/-0.005 (stat.)+/-0.009 (syst.) GeV is also observed, in both the Upsilon(1S)gamma and Upsilon(2S)gamma decay modes. This is interpreted as the chi_b(3P) system.Comment: 5 pages plus author list (18 pages total), 2 figures, 1 table, corrected author list, matches final version in Physical Review Letter

Search for displaced vertices arising from decays of new heavy particles in 7 TeV pp collisions at ATLAS

We present the results of a search for new, heavy particles that decay at a significant distance from their production point into a final state containing charged hadrons in association with a high-momentum muon. The search is conducted in a pp-collision data sample with a center-of-mass energy of 7 TeV and an integrated luminosity of 33 pb^-1 collected in 2010 by the ATLAS detector operating at the Large Hadron Collider. Production of such particles is expected in various scenarios of physics beyond the standard model. We observe no signal and place limits on the production cross-section of supersymmetric particles in an R-parity-violating scenario as a function of the neutralino lifetime. Limits are presented for different squark and neutralino masses, enabling extension of the limits to a variety of other models.Comment: 8 pages plus author list (20 pages total), 8 figures, 1 table, final version to appear in Physics Letters