Bounds for Bose-Einstein Correlation Functions

Bounds for the correlation functions of identical bosons are discussed for the general case of a Gaussian density matrix. In particular, for a purely chaotic system the two-particle correlation function must always be greater than one. On the other hand, in the presence of a coherent component the correlation function may take values below unity. The experimental situation is briefly discussed.Comment: 7 pages, LaTeX, DMR-THEP-93-5/

Convexity in partial cubes: the hull number

We prove that the combinatorial optimization problem of determining the hull number of a partial cube is NP-complete. This makes partial cubes the minimal graph class for which NP-completeness of this problem is known and improves some earlier results in the literature. On the other hand we provide a polynomial-time algorithm to determine the hull number of planar partial cube quadrangulations. Instances of the hull number problem for partial cubes described include poset dimension and hitting sets for interiors of curves in the plane. To obtain the above results, we investigate convexity in partial cubes and characterize these graphs in terms of their lattice of convex subgraphs, improving a theorem of Handa. Furthermore we provide a topological representation theorem for planar partial cubes, generalizing a result of Fukuda and Handa about rank three oriented matroids.Comment: 19 pages, 4 figure

Pregnancy in women with perinatally acquired HIV-infection: Outcomes and challenges

This is a retrospective comparison of pregnant women with perinatally acquired HIV-infection (PAH) with a cohort of pregnant women with behaviorally acquired HIV-infection (BAH). PAH cases (11 women) included all pregnant adolescents followed at our HIV clinic from January 2000 to January 2009. BAH cases (27 women) were randomly selected from all deliveries within the study period at the same institution. Demographics, mode of delivery, CD4+ counts, and viral loads (VLs) before, during, and six months postpartum, as well as neonatal outcomes, were reviewed

Unintended pregnancy and contraception use among African women living with HIV: Baseline analysis of the multi-country US PEPFAR PROMOTE cohort

Background About 90% of unintended pregnancies are attributed to non-use of effective contraception–tubal ligation, or reversible effective contraception (REC) including injectables, oral pills, intra-uterine contraceptive device (IUCD), and implant. We assessed the prevalence of unintended pregnancy and factors associated with using RECs, and Long-Acting-Reversible-Contraceptives (LARCs)–implants and IUCDs, among women living with HIV (WLHIV) receiving antiretroviral therapy (ART). Methods We conducted cross-sectional analyses of the US-PEPFAR PROMOTE study WLHIV on ART at enrollment. Separate outcome (REC and LARC) modified-Poisson regression models were used to estimate prevalence risk ratio (PRR) and corresponding 95% confidence interval (CI). Results Of 1,987 enrolled WLHIV, 990 (49.8%) reported their last/current pregnancy was unintended; 1,027/1,254 (81.9%) non-pregnant women with a potential to become pregnant reported current use of effective contraception including 215/1,254 (17.1%) LARC users. Compared to Zimbabwe, REC rates were similar in South Africa, aPRR = 0.97 (95% CI: 0.90–1.04), p = 0.355, lower in Malawi, aPRR = 0.84 (95% CI: 0.78–0.91), p<0.001, and Uganda, 0.82 (95% CI: 0.73–0.91), p<0.001. Additionally, REC use was independently associated with education attained, primary versus higher education, aPRR = 1.10 (95% CI: 1.02–1.18), p = 0.013; marriage/stable union, aPRR = 1.10 (95% CI: 1.01–1.21), p = 0.039; no desire for another child, PRR = 1.10 (95% CI: 1.02–1.16), p = 0.016; infrequent sex (none in the last 3 months), aPRR = 1.24 (95% CI: 1.15–1.33), p<0001; and controlled HIV load (≤ 1000 copies/ml), PRR = 1.10 (95% CI: 1.02–1.19), p = 0.014. LARC use was independently associated with country (Zimbabwe ref: South Africa, PRR = 0.39 (95% CI: 0.26–0.57), p<0.001; Uganda, PRR = 0.65 (95% CI: 0.42–1.01), p = 0.054; and Malawi, aPRR = 0.87 (95% CI: 0.64–1.19), p = 0.386; HIV load (≤ 1000 copies/ml copies/ml), aPRR=1.73 (95% CI: 1.26–2.37), p<0.001; and formal/self-employment, aPRR = 1.37 (95% CI: 1.02-1.91), p = 0.027. Conclusions Unintended pregnancy was common while use of effective contraception methods particularly LARCs was low among these African WLHIV. HIV viral load, education, sexual-activity, fertility desires, and economic independence are pertinent individual-level factors integral to the multi-level barriers to utilization of effective contraception among African WLHIV. National programs should prioritize strategies for effective integration of HIV and reproductive health care in the respective African countries

Spinor condensates and light scattering from Bose-Einstein condensates

These notes discuss two aspects of the physics of atomic Bose-Einstein condensates: optical properties and spinor condensates. The first topic includes light scattering experiments which probe the excitations of a condensate in both the free-particle and phonon regime. At higher light intensity, a new form of superradiance and phase-coherent matter wave amplification were observed. We also discuss properties of spinor condensates and describe studies of ground--state spin domain structures and dynamical studies which revealed metastable excited states and quantum tunneling.Comment: 58 pages, 33 figures, to appear in Proceedings of Les Houches 1999 Summer School, Session LXXI

Attentive Learning of Sequential Handwriting Movements: A Neural Network Model

Defense Advanced research Projects Agency and the Office of Naval Research (N00014-95-1-0409, N00014-92-J-1309); National Science Foundation (IRI-97-20333); National Institutes of Health (I-R29-DC02952-01)

Results of the Search for Strange Quark Matter and Q-balls with the SLIM Experiment

The SLIM experiment at the Chacaltaya high altitude laboratory was sensitive to nuclearites and Q-balls, which could be present in the cosmic radiation as possible Dark Matter components. It was sensitive also to strangelets, i.e. small lumps of Strange Quark Matter predicted at such altitudes by various phenomenological models. The analysis of 427 m^2 of Nuclear Track Detectors exposed for 4.22 years showed no candidate event. New upper limits on the flux of downgoing nuclearites and Q-balls at the 90% C.L. were established. The null result also restricts models for strangelets propagation through the Earth atmosphere.Comment: 14 pages, 11 EPS figure

Family-school connections and internalizing problems among children living with asthma in urban, low-income neighborhoods

Children with asthma living in urban environments are at risk for experiencing internalizing problems and difficulties at school due to social context and health-related stressors. Parent confidence and participation in the school and children’s attitudes about school were explored in association with children’s depressed mood and school anxiety. Forty-five parent—child dyads were recruited from urban community health centers. Most participants were members of ethnic minority groups. Hierarchical multiple regression analyses revealed that higher levels of parent confidence in the school were associated with fewer symptoms of school anxiety in children. Children’s attitudes toward school moderated the relation between parent participation in the school and children’s depressed mood. Specifically, lower levels of parent participation were associated with higher levels of depressed mood only for children with the least positive school attitudes. Although preliminary, these results suggest the importance of attending to family—school connections to optimize the school-related psychological functioning of children living with asthma in urban environments

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