Squeezed K^+ K^- correlations in high energy heavy ion collisions

The hot and dense medium formed in high energy heavy ion collisions may modify some hadronic properties. In particular, if hadron masses are shifted in-medium, it was demonstrated that this could lead to back-to-back squeezed correlations (BBC) of particle-antiparticle pairs. Although well-established theoretically, the squeezed correlations have not yet been discovered experimentally. A method has been suggested for the empirical search of this effect, which was previously illustrated for phi-phi pairs. We apply here the formalism and the suggested method to the case of K^+ K^- pairs, since they may be easier to identify experimentally. The time distribution of the emission process plays a crucial role in the survival of the BBC's. We analyze the cases where the emission is supposed to occur suddenly or via a Lorentzian distribution, and compare with the case of a Levy distribution in time. Effects of squeezing on the correlation function of identical particles are also analyzed.Comment: 9 pages and 6 figures (figures 2 to 6 contain 4 plots each). Paragraph added to text, figures 2 to 6 revised for improving visualizatio

Squeezed correlations of strange particle-antiparticles

Squeezed correlations of hadron-antihadron pairs are predicted to appear if their masses are modified in the hot and dense medium formed in high energy heavy ion collisions. If discovered experimentally, they would be an unequivocal evidence of in-medium mass shift found by means of hadronic probes. We discuss a method proposed to search for this novel type of correlation, illustrating it by means of D_s-mesons with in-medium shifted masses. These particles are expected to be more easily detected and identified in future upgrades at RHIC.Comment: 6 pages, 3 figures with parts a) and b), SQM 2009 contribution; added acknowledgmen

Screening tests, information, and the health-education gradient

The association between health outcomes and education - the health-education gradient - is widely documented but little is known about its source. Using microeconomic data on a sample of individuals aged 50+ in eight European countries, we find that education and cognitive skills (such as verbal fluency) are associated with a greater propensity for standard screening tests (mammography and colonoscopy). In order to study the role of information on the decision to screen, we test whether the health-education gradient varies with the quality of the information provided by the health care system, as proxied by the quality of the General Practitioner. Using an Instrumental Variable approach to control for the potential endogeneity of the GP quality score, we find evidence of a strong and significant complementarity between education and quality of primary care. We interpret this result as evidence that health-education gradient can be explained, at least in part, by the fact that better educated individuals are more able to process and internalize health related information as provided by GPs

Integrated Thermal-structural-electromagnetic Design Optimization of Large Space Antenna Reflectors

The requirements for low mass and high electromagnetic (EM) performance in large, flexible space antenna structures is motivating the development of a systematic procedure for antenna design. In contrast to previous work which concentrated on reducing rms distortions of the reflector surface, thereby indirectly increasing antenna performance, the current work involves a direct approach to increasing electromagnetic performance using mathematical optimization. The thermal, structural, and EM analyses are fully integrated in the context of an optimization procedure, and consequently, the interaction of the various responses is accounted for directly and automatically. Preliminary results are presented for sizing cross-sectional areas of a tetrahedral truss reflector. The results indicate potential for this integrated procedure from the standpoint of mass reduction, performance increase, and efficiency of the design process

Integrated structure electromagnetic optimization of large space antenna reflectors

The requirements for extremely precise and powerful large space antenna reflectors have motivated the development of a procedure for shape control of the reflector surface. A mathematical optimization procedure has been developed which improves antenna performance while minimizing necessary shape correction effort. In contrast to previous work which proposed controlling the rms distortion error of the surface thereby indirectly improving antenna performance, the current work includes electromagnetic (EM) performance calculations as an integral of the control procedure. The application of the procedure to a radiometer design with a tetrahedral truss backup structure demonstrates the potential for significant improvement. The results indicate the benefit of including EM performance calculations in procedures for shape control of large space antenna reflectors

Advanced turboprop noise prediction: Development of a code at NASA Langley based on recent theoretical results

The development of a high speed propeller noise prediction code at Langley Research Center is described. The code utilizes two recent acoustic formulations in the time domain for subsonic and supersonic sources. The structure and capabilities of the code are discussed. Grid size study for accuracy and speed of execution on a computer is also presented. The code is tested against an earlier Langley code. Considerable increase in accuracy and speed of execution are observed. Some examples of noise prediction of a high speed propeller for which acoustic test data are available are given. A brisk derivation of formulations used is given in an appendix

The phylogeography and population genetic structure of least cisco (Coregonus sardinella) in Alaska

Thesis (M.S.) University of Alaska Fairbanks, 2013The least cisco (Coregonus sardinella) is a whitefish species broadly distributed across the Arctic regions of Russia, Alaska, and Canada, and little is known about the genetic relationships among groups within this species. We investigated the genetic relationships among least cisco on two landscape scales. On a broader landscape scale, we investigated the relationships among populations across the state of Alaska by comparing mitochondria) DNA (mtDNA) sequences. On a finer landscape scale, we investigated the relationships among least cisco populations in closely located lakes on the Arctic Coastal Plain by comparing microsatellite DNA haplotypes. Data from mtDNA suggest that least cisco are relatively diverse across Alaska, with 68 unique haplotypes found in 305 individuals and a large proportion of genetic variation is shared across Alaska, but this variation is not homogeneously distributed across all regions and for all haplotype groups. Interpretation of microsatellite data was limited. Overall, the data suggest that least cisco populations are currently isolated from one another. Isolation also occurred historically, accounting for divergence among major Glades. But general recontact events occurred as isolated populations migrated and colonized new habitats, accounting for the heterogeneity found across Alaska. Ultimately, Alaskan least cisco may have functioned as a metapopulation historically, but present populations are too isolated to be considered a metapopulation today

Search for Squeezed-Pair Correlations at RHIC

Squeezed correlations of particle-antiparticle pairs, also called Back-to-Back Correlations, are predicted to appear if the hadron masses are modified in the hot and dense hadronic medium formed in high energy nucleus-nucleus collisions. Although well-established theoretically, the squeezed-particle correlations have not yet been searched for experimentally in high energy hadronic or heavy ion collisions, clearly requiring optimized forms to experimentally search for this effect. Within a non-relativistic treatment developed earlier we show that one promising way to search for the BBC signal is to look into the squeezed correlation function of pairs of phi-mesons at RHIC energies, plotted in terms of the average momentum of the pair, K12=(k1+k2)/2. This variable's modulus, 2|K12|, is the non-relativistic limit of the variable Q_bbc, introduced herewith. The squeezing effects on the HBT correlation function are also discussed.Comment: 4 pages, 2 figures. To be published in the Proceedings of Quark Matter 2008, Jaipur, Indi

Testing the Resolving Power of 2-D K^+ K^+ Interferometry

Adopting a procedure previously proposed to quantitatively study two-dimensional pion interferometry, an equivalent 2-D chi^2 analysis was performed to test the resolving power of that method when applied to less favorable conditions, i.e., if no significant contribution from long lived resonances is expected, as in kaon interferometry. For that purpose, use is made of the preliminary E859 K^+ K^+ interferometry data from Si+Au collisions at 14.6 AGeV/c. As expected, less sensitivity is achieved in the present case, although it still is possible to distinguish two distinct decoupling geometries. The present analysis seems to favor scenarios with no resonance formation at the AGS energy range, if the preliminary K^+ K^+ data are confirmed. The possible compatibility of data with zero decoupling proper time interval, conjectured by the 3-D experimental analysis, is also investigated and is ruled out when considering more realistic dynamical models with expanding sources. These results, however, clearly evidence the important influence of the time emission interval on the source effective transverse dimensions. Furthermore, they strongly emphasize that the static Gaussian parameterization, commonly used to fit data, cannot be trusted under more realistic conditions, leading to distorted or even wrong interpretation of the source parameters!Comment: 11 pages, RevTeX, 4 Postscript figures include

Retirement expectations, pension reforms, and their effect on private wealth accumulation

We estimate the effect of pension reforms on households’ expectations of retirement outcomes and private wealth accumulation decisions exploiting a decade of intense Italian pension reforms as a source of exogenous variation in expected pension wealth. The Survey of Household Income and Wealth, a large random sample of the Italian population, elicits expectations of the age at which workers expect to retire and of the ratio of pension benefits to pre-retirement income between 1989 and 2002. We find that workers have revised expectations in the direction suggested by the reform and that there is substantial offset between private wealth and perceived pension wealth, particularly by workers that are better informed about their pension wealth