Ordinary and Extraordinary Hadrons

Resonances and enhancements in meson-meson scattering can be divided into two classes distinguished by their behavior as the number of colors N_c in QCD becomes large: The first are ordinary mesons that become stable as N_c goes to infinity. This class includes textbook q-bar q mesons as well as glueballs and hybrids. The second class, extraordinary mesons, are enhancements that disappear as N_c goes to infinity; they subside into the hadronic continuum. This class includes indistinct and controversial objects that have been classified as q-bar q-bar q q mesons or meson-meson molecules. Pelaez's study of the N_c dependence of unitarized chiral dynamics illustrates both classes: the p-wave pi-pi and K-pi resonances, the rho(770) and K*(892), behave as ordinary mesons; the s-wave pi-pi and K-pi enhancements, the sigma(600) and kappa(800), behave like extraordinary mesons. Ordinary mesons resemble Feshbach resonances while extraordinary mesons look more like effects due to potentials in meson-meson scattering channels. I build and explore toy models along these lines. Finally I discuss some related dynamical issues affecting the interpretation of extraordinary mesons.Comment: 18 pages, 10 figures, talk presented at the 2006 Yukawa International Seminar: New Frontiers in QCD, Kyoto University, November 2006. This talk is dedicated to the memory of R. H. Dalit

The Chemical Compositions of Very Metal-Poor Stars HD 122563 and HD 140283; A View From the Infrared

From high resolution (R = 45,000), high signal-to-noise (S/N > 400) spectra gathered with the Immersion Grating Infrared Spectrograph (IGRINS) in the H and K photometric bands, we have derived elemental abundances of two bright, well-known metal-poor halo stars: the red giant HD 122563 and the subgiant HD 140283. Since these stars have metallicities approaching [Fe/H] = -3, their absorption features are generally very weak. Neutral-species lines of Mg, Si, S and Ca are detectable, as well as those of the light odd-Z elements Na and Al. The derived IR-based abundances agree with those obtained from optical-wavelength spectra. For Mg and Si the abundances from the infrared transitions are improvements to those derived from shorter wavelength data. Many useful OH and CO lines can be detected in the IGRINS HD 122563 spectrum, from which derived O and C abundances are consistent to those obtained from the traditional [O I] and CH features. IGRINS high resolutions H- and K-band spectroscopy offers promising ways to determine more reliable abundances for additional metal-poor stars whose optical features are either not detectable, or too weak, or are based on lines with analytical difficulties.Comment: Accepted for publication in ApJ (28 pages, 4 tables, 6 figures

Size effects and depolarization field influence on the phase diagrams of cylindrical ferroelectric nanoparticles

Ferroelectric nanoparticles of different shape and their nanocomposites are actively studied in modern physics. Because of their applications in many fields of nanotechnology, the size effects and the possible disappearance of ferroelectricity at a critical particle volume attract a growing scientific interest. In this paper we study the size effects of the cylindrical nanoparticle phase diagrams allowing for effective surface tension and depolarization field influence. The Euler-Lagrange equations were solved by direct variational method. The approximate analytical expression for the paraelectric-ferroelectric transition temperature dependence on nanoparticle sizes, polarization gradient coefficient, extrapolation length, effective surface tension and electrostriction coefficient was derived. It was shown that the transition temperature could be higher than the one of the bulk material for nanorods and nanowires in contrast to nanodisks, where the decrease takes place. The critical sizes and volume of ferroelectric-paraelectric phase transition are calculated. We proved that among all cylindrical shapes a nanobar reveals the minimal critical volume. We predicted the enhancement of ferroelectric properties in nanorods and nanowires. Obtained results explain the observed ferroelectricity enhancement in nanorods and could be very useful for elaboration of modern nanocomposites with perfect polar properties.Comment: 22 pages, 7 figures, 1 tabl

Effects of Peritraumatic Alcohol Intoxication on Intrusive Memories Following Exposure to an Analog Trauma

Intrusive memories and associated symptoms of posttraumatic stress disorder (PTSD) represent a significant public health problem, often leading to persistent physical and psychological difficulties experienced by victims long after the traumatic event, contributing to healthcare costs and loss of productivity. Research examining etiological factors that contribute to PTSD is needed in order to expand basic knowledge and to inform the development of prevention and intervention strategies. Although acute alcohol intoxication has the potential to impact established risk factors for the development of intrusive memories (e.g., via stress response, cognitive processing), and trauma—particularly sexual assault—often occurs under the influence of alcohol, the influence of peritraumatic (i.e., at the time of assault) alcohol intoxication on post-assault trauma symptoms is not well understood. To address this issue, the current study utilized an experimental design, including lab-based alcohol administration (high dose of .72 g/kg, low dose of .36 g/kg, and a placebo beverage), a well-accepted analog trauma exposure paradigm (a film with distressing or “traumatic” content), and ecological momentary assessment of intrusive memories. Results from 98 community women (ages 21 to 30, without a personal history of victimization) revealed peritraumatic intoxication did impact the occurrence of intrusive memories. Specifically, a marginally significant indirect effect showed that alcohol myopia disrupted cognitive processing and formation of trauma memories, resulting in increased intrusive memories at high levels of intoxication. At the same time, those who consumed high or low doses of alcohol displayed a dampened stress response, which reduced intrusive memories. Findings highlight the influence of peritraumatic cognitive impairment and stress response on the development of intrusive memories. Though alcohol influenced these risk factors simultaneously and in opposite directions, overall, participants in the high dose condition reported more intrusive memories than those in the placebo and low dose conditions. These findings reflect the importance of prevention and intervention programs aimed at reducing alcohol-involved victimization. Adviser: David DiLill

Thermodynamics of nanodomain formation and breakdown in Scanning Probe Microscopy: Landau-Ginzburg-Devonshire approach

Thermodynamics of tip-induced nanodomain formation in scanning probe microscopy of ferroelectric films and crystals is studied using the Landau-Ginzburg-Devonshire phenomenological approach. The local redistribution of polarization induced by the biased probe apex is analyzed including the effects of polarization gradients, field dependence of dielectric properties, intrinsic domain wall width, and film thickness. The polarization distribution inside subcritical nucleus of the domain preceding the nucleation event is very smooth and localized below the probe, and the electrostatic field distribution is dominated by the tip. In contrast, polarization distribution inside the stable domain is rectangular-like, and the associated electrostatic fields clearly illustrate the presence of tip-induced and depolarization field components. The calculated coercive biases of domain formation are in a good agreement with available experimental results for typical ferroelectric materials. The microscopic origin of the observed domain tip elongation in the region where the probe electric field is much smaller than the intrinsic coercive field is the positive depolarization field in front of the moving counter domain wall. For infinitely thin domain walls local domain breakdown through the sample depth appears. The results obtained here are complementary to the Landauer-Molotskii energetic approach.Comment: 35 pages, 8 figures, suplementary attached, to be submitted to Phys. Rev.

The Long-Baseline Neutrino Experiment: Exploring Fundamental Symmetries of the Universe

The preponderance of matter over antimatter in the early Universe, the dynamics of the supernova bursts that produced the heavy elements necessary for life and whether protons eventually decay --- these mysteries at the forefront of particle physics and astrophysics are key to understanding the early evolution of our Universe, its current state and its eventual fate. The Long-Baseline Neutrino Experiment (LBNE) represents an extensively developed plan for a world-class experiment dedicated to addressing these questions. LBNE is conceived around three central components: (1) a new, high-intensity neutrino source generated from a megawatt-class proton accelerator at Fermi National Accelerator Laboratory, (2) a near neutrino detector just downstream of the source, and (3) a massive liquid argon time-projection chamber deployed as a far detector deep underground at the Sanford Underground Research Facility. This facility, located at the site of the former Homestake Mine in Lead, South Dakota, is approximately 1,300 km from the neutrino source at Fermilab -- a distance (baseline) that delivers optimal sensitivity to neutrino charge-parity symmetry violation and mass ordering effects. This ambitious yet cost-effective design incorporates scalability and flexibility and can accommodate a variety of upgrades and contributions. With its exceptional combination of experimental configuration, technical capabilities, and potential for transformative discoveries, LBNE promises to be a vital facility for the field of particle physics worldwide, providing physicists from around the globe with opportunities to collaborate in a twenty to thirty year program of exciting science. In this document we provide a comprehensive overview of LBNE's scientific objectives, its place in the landscape of neutrino physics worldwide, the technologies it will incorporate and the capabilities it will possess.Comment: Major update of previous version. This is the reference document for LBNE science program and current status. Chapters 1, 3, and 9 provide a comprehensive overview of LBNE's scientific objectives, its place in the landscape of neutrino physics worldwide, the technologies it will incorporate and the capabilities it will possess. 288 pages, 116 figure

Triplication of a 21q22 region contributes to B cell transformation through HMGN1 overexpression and loss of histone H3 lysine 27 trimethylation

Down syndrome confers a 20-fold increased risk of B cell acute lymphoblastic leukemia (B-ALL)1 and polysomy 21 is the most frequent somatic aneuploidy amongst all B-ALLs2. Yet, the mechanistic links between chr.21 triplication and B-ALL remain undefined. Here we show that germline triplication of only 31 genes orthologous to human chr.21q22 confers murine progenitor B cell self-renewal in vitro, maturation defects in vivo, and B-ALL with either BCR-ABL or CRLF2 with activated JAK2. Chr.21q22 triplication suppresses H3K27me3 in progenitor B cells and B-ALLs, and “bivalent” genes with both H3K27me3 and H3K4me3 at their promoters in wild-type progenitor B cells are preferentially overexpressed in triplicated cells. Strikingly, human B-ALLs with polysomy 21 are distinguished by their overexpression of genes marked with H3K27me3 in multiple cell types. Finally, overexpression of HMGN1, a nucleosome remodeling protein encoded on chr.21q223–5, suppresses H3K27me3 and promotes both B cell proliferation in vitro and B-ALL in vivo

Depressive Symptoms following Recent Sexual Assault: The Role of Drug and Alcohol Use, Acute Stress, and Assault Characteristics

Sexual assault is a common traumatic experience that can have a wide-ranging impact on psychological functioning, including experience of depressive symptoms. While many studies have examined lifetime rates of depression among those with sexual assault history, less is known regarding risk factors for depressive symptoms following recent sexual assault. The study examined whether drug use history is uniquely related to depressive symptoms following recent assault. Method: N = 65 individuals (5.4% female; 73.8% white; M(SD)age = 28.89 (10.29)) who had recently experienced sexual assault (less than 60 days) and completed a SAMFE were interviewed via phone and completed questionnaires regarding depressive and acute/posttraumatic stress symptoms and substance use history. Demographic information as well as information related to the assault was also collected. Results: 68.7% of the sample reported clinically significant levels of depressive symptoms (PHQ-9 scores ≥ 12). In a linear mixed model, drug use was significantly related depressive symptoms (β = .19, p = .04), even controlling for acute/posttraumatic stress (β = .72, p .05). Conclusion: Results highlight the potential role of drug use in increasing risk for experiencing clinically significant depressive symptoms following recent assault

Friends-Based Protective Strategies and Unwanted Sexual Experiences: A Daily Diary Examination of First Year College Women

Risk for unwanted sexual experiences can emerge in social contexts—the same contexts that early college women navigate with their friends. Though friends naturally engage in prevention strategies, less is known about how capable guardianship influences risk. Using multilevel structural equation modeling, the present study examined guardianship at the person and situation levels. First-year college women (N = 132) completed eight weekends of daily surveys. We examined whether guardianship (e.g., more friends present, greater proportion of female friends, no intoxicated friends) would reduce unwanted sexual experience risk and if this relation was mediated by friends-based strategy use. An alternative model was also tested with the same predictors, but with unwanted sexual experiences as the mediator and friends-based strategy use as the outcome. Over half (58%) of extended weekend nights with friends involved drinking or using drugs. Friends-based strategies were used on 29% of nights. Across models, being with one or more intoxicated friends was associated with friends-based strategy use and an unwanted sexual experience, but only at the situation level. Parents, educators, and policy makers can encourage college women to draw on their social networks to enhance safety. Interventions could incorporate more universal strategies for responding to risk in social contexts

A Prospective Study of Predictors and Consequences of Hooking Up for Sexual Minority Women

Hooking up, which refers to a sexual encounter (ranging from kissing to penetrative sex) between individuals who are not in a committed relationship, is an increasingly normative form of sexual exploration among emerging adults. Past research has focused on hookups within a heteronormative context, and some of this work has examined hookups as a way to cope with distress. Building on this work, we examined the role of hookups as a means for lesbian and bisexual women to cope with minority stress through increasing connection and engagement with the LGBTQ (lesbian/gay/bisexual/transgender/queer or questioning) community. A nationally recruited sample of 520 lesbian and bisexual women ages 18 to 25 completed questionnaires regarding their hookup behaviors as part of a longitudinal study. Childhood sexual abuse, posttraumatic stress symptoms, alcohol use, minority stress, and involvement and connectedness with the LGBTQ community were also assessed. First, regression analyses were used to examine baseline predictors of hookup behaviors reported at a 12-month follow-up. Findings revealed that alcohol use was associated with a greater likelihood of any subsequent hookups, and individuals reporting more minority stress subsequently hooked up with more partners. Second, hookup behaviors at 12 months were examined as predictors of outcomes at a 24-month follow-up, after controlling for baseline variables. Findings revealed that hookup behaviors were associated with reduced minority stress as well as increased involvement with and connectedness to the LGBTQ community, suggesting hookups may serve a protective function. Overall, findings support the notion that for sexual minority women, hookups may operate as a means of coping and connection