Entanglement of identical particles and reference phase uncertainty

We have recently introduced a measure of the bipartite entanglement of identical particles, E_P, based on the principle that entanglement should be accessible for use as a resource in quantum information processing. We show here that particle entanglement is limited by the lack of a reference phase shared by the two parties, and that the entanglement is constrained to reference-phase invariant subspaces. The super-additivity of E_P results from the fact that this constraint is weaker for combined systems. A shared reference phase can only be established by transferring particles between the parties, that is, with additional nonlocal resources. We show how this nonlocal operation can increase the particle entanglement.Comment: 8 pages, no figures. Invited talk given at EQIS'03, Kyoto, September, 2003. Minor typos corrected, 1 reference adde

Systematic review of trends in emergency department attendances : an Australian perspective

Emergency departments (EDs) in many developed countries are experiencing increasing pressure due to rising numbers of patient presentations and emergency admissions. Reported increases range up to 7% annually. Together with limited inpatient bed capacity, this contributes to prolonged lengths of stay in the ED; disrupting timely access to urgent care, posing a threat to patient safety. The aim of this review is to summarise the findings of studies that have investigated the extent of and the reasons for increasing emergency presentations. To do this, a systematic review and synthesis of published and unpublished reports describing trends and underlying drivers associated with the increase in ED presentations in developed countries was conducted. Most published studies provided evidence of increasing ED attendances within developed countries. A series of inter-related factors have been proposed to explain the increase in emergency demand. These include changes in demography and in the organisation and delivery of healthcare services, as well as improved health awareness and community expectations arising from health promotion campaigns. The factors associated with increasing ED presentations are complex and inter-related and include rising community expectations regarding access to emergency care in acute hospitals. A systematic investigation of the demographic, socioeconomic and health-related factors highlighted by this review is recommended. This would facilitate untangling the dynamics of the increase in emergency demand

Regularization-robust preconditioners for time-dependent PDE constrained optimization problems

In this article, we motivate, derive and test �effective preconditioners to be used with the Minres algorithm for solving a number of saddle point systems, which arise in PDE constrained optimization problems. We consider the distributed control problem involving the heat equation with two diff�erent functionals, and the Neumann boundary control problem involving Poisson's equation and the heat equation. Crucial to the eff�ectiveness of our preconditioners in each case is an eff�ective approximation of the Schur complement of the matrix system. In each case, we state the problem being solved, propose the preconditioning approach, prove relevant eigenvalue bounds, and provide numerical results which demonstrate that our solvers are eff�ective for a wide range of regularization parameter values, as well as mesh sizes and time-steps

Europium, Samarium, and Neodymium Isotopic Fractions in Metal-Poor Stars

We have derived isotopic fractions of europium, samarium, and neodymium in two metal-poor giants with differing neutron-capture nucleosynthetic histories. These isotopic fractions were measured from new high resolution (R ~ 120,000), high signal-to-noise (S/N ~ 160-1000) spectra obtained with the 2dCoude spectrograph of McDonald Observatory's 2.7m Smith telescope. Synthetic spectra were generated using recent high-precision laboratory measurements of hyperfine and isotopic subcomponents of several transitions of these elements and matched quantitatively to the observed spectra. We interpret our isotopic fractions by the nucleosynthesis predictions of the stellar model, which reproduces s-process nucleosynthesis from the physical conditions expected in low-mass, thermally-pulsing stars on the AGB, and the classical method, which approximates s-process nucleosynthesis by a steady neutron flux impinging upon Fe-peak seed nuclei. Our Eu isotopic fraction in HD 175305 is consistent with an r-process origin by the classical method and is consistent with either an r- or an s-process origin by the stellar model. Our Sm isotopic fraction in HD 175305 suggests a predominantly r-process origin, and our Sm isotopic fraction in HD 196944 is consistent with an s-process origin. The Nd isotopic fractions, while consistent with either r-process or s-process origins, have very little ability to distinguish between any physical values for the isotopic fraction in either star. This study for the first time extends the n-capture origin of multiple rare earths in metal-poor stars from elemental abundances to the isotopic level, strengthening the r-process interpretation for HD 175305 and the s-process interpretation for HD196944.Comment: 40 pages, 16 figures. Accepted for publication in ApJ. Full versions of tables 4 and 5 are available from the first author upon reques

Measuring Molecular, Neutral Atomic, and Warm Ionized Galactic Gas Through X-Ray Absorption

We study the column densities of neutral atomic, molecular, and warm ionized Galactic gas through their continuous absorption of extragalactic X-ray spectra at |b| > 25 degrees. For N(H,21cm) < 5x10^20 cm^-2 there is an extremely tight relationship between N(H,21cm) and the X-ray absorption column, N(xray), with a mean ratio along 26 lines of sight of N(xray)/N(H,21cm) = 0.972 +- 0.022. This is significantly less than the anticpated ratio of 1.23, which would occur if He were half He I and half He II in the warm ionized component. We suggest that the ionized component out of the plane is highly ionized, with He being mainly He II and He III. In the limiting case that H is entirely HI, we place an upper limit on the He abundance in the ISM of He/H <= 0.103. At column densities N(xray) > 5x10^20 cm^-2, which occurs at our lower latitudes, the X-ray absorption column N(xray) is nearly double N(H,21cm). This excess column cannot be due to the warm ionized component, even if He were entirely He I, so it must be due to a molecular component. This result implies that for lines of sight out of the plane with |b| ~ 30 degrees, molecular gas is common and with a column density comprable to N(H,21cm). This work bears upon the far infrared background, since a warm ionized component, anticorrelated with N(H,21cm), might produce such a background. Not only is such an anticorrelation absent, but if the dust is destroyed in the warm ionized gas, the far infrared background may be slightly larger than that deduced by Puget et al. (1996).Comment: 1 AASTeX file, 14 PostScript figure files which are linked within the TeX fil

Fast iterative solution of reaction-diffusion control problems arising from chemical processes

PDE-constrained optimization problems, and the development of preconditioned iterative methods for the efficient solution of the arising matrix system, is a field of numerical analysis that has recently been attracting much attention. In this paper, we analyze and develop preconditioners for matrix systems that arise from the optimal control of reaction-diffusion equations, which themselves result from chemical processes. Important aspects in our solvers are saddle point theory, mass matrix representation and effective Schur complement approximation, as well as the outer (Newton) iteration to take account of the nonlinearity of the underlying PDEs

Detecting and Studying e+e−→H0A0,H+H−e^+e^-\to H^0A^0,H^+H^- in the MSSM: Implications of Supersymmetric Decays and Discriminating GUT Scenarios

We demonstrate that supersymmetric decays, as typified by the predictions of several GUT-scale boundary condition choices, do not prevent detection of $Z^* \to H^0A^0,H^+H^-$, at a $1-4$ TeV $e^+e^-$ or $\mu^+\mu^-$ collider operating at anticipated luminosity. For much of parameter space the relative branching ratios for various SUSY and non-SUSY decays can be measured with sufficient accuracy that different GUT-scale boundary condition choices can be distinguished from one another at a very high confidence level.Comment: 54 pages, full postscript file also available via anonymous ftp at ftp://ucdhep.ucdavis.edu/gunion/pair.p

Affective problems and decline in cognitive state in older adults: a systematic review and meta-analysis

Evidence suggests that affective problems, such as depression and anxiety, increase risk for late-life dementia. However, the extent to which affective problems influence cognitive decline, even many years prior to clinical diagnosis of dementia, is not clear. The present study systematically reviews and synthesises the evidence for the association between affective problems and decline in cognitive state (i.e. decline in non-specific cognitive function) in older adults. An electronic search of PubMed, PsycInfo and ScienceDirect was conducted to identify studies of the association between depression and anxiety separately and decline in cognitive state. Key inclusion criteria were prospective, longitudinal designs with a minimum follow-up period of one year. Data extraction and methodological quality assessment using the STROBE checklist were conducted independently by two raters. A total of 34 studies (n=71,244) met eligibility criteria, with 32 studies measuring depression (n=68,793), and 5 measuring anxiety (n=4,698). A multi-level meta-analysis revealed that depression assessed as a binary predictor (OR=1.36, 95% CIs: 1.05-1.76, p=.02) or a continuous predictor (B=-0.008, 95% CIs: -0.015, -0.002, p=.012; OR=0.992, 95% CIs: 0.985-0.998) was significantly associated with decline in cognitive state. The number of anxiety studies were insufficient for meta-analysis and are instead described in a narrative review. Results of the present study improve current understanding of the temporal nature of the association between affective problems and decline in cognitive state. They also suggest that cognitive function need to be monitored closely in individuals with affective disorders, as these individuals may be at a particular risk of greater cognitive decline

Which primary care practitioners have poor human papillomavirus (HPV) knowledge? A step towards informing the development of professional education initiatives

Background: Primary care practitioners (PCP) play key roles in cervical cancer prevention. Human papillomavirus (HPV) knowledge is an important influence on PCPs’ cervical cancer prevention-related behaviours. We investigated HPV knowledge, and associated factors, among general practitioners (GPs) and practice nurses. Methods: A survey, including factual questions about HPV infection and vaccination, was mailed to GPs and practice nurses in Ireland. Multivariable logistic regression was used to determine which PCPs had low knowledge (questions correctly answered: infection ≤5/11; vaccination: ≤4/10). Questions least often answered correctly were identified. Results: 697 PCPs participated. For HPV infection, GPs and practice nurses answered a median of nine and seven questions correctly, respectively (p⅓ of PCPs. Conclusions: There are important limitations in HPV infection and vaccination knowledge among PCPs. By identifying factors associated with poor knowledge, and areas of particular uncertainty, these results can inform development of professional education initiatives thereby ensuring women have access to uniformly high-quality HPV-related information and advice