Amygdala volume and hypothalamic-pituitary-adrenal axis reactivity to social stress

The amygdala plays a central role in emotional processing and has an activating influence on the hypothalamic-pituitary-adrenal (HPA) axis. Structural changes in the amygdala have been associated with early adversity and, in principle, may contribute to the later emergence of emotional pathologies by influencing the way that the brain responds to stress provocation. The present study examined the relationship between amygdala volumes and cortisol secretion in response to a social stressor among young adults who were or were not exposed to maternal postnatal depression (PND) early in development (referred to as PND offspring and controls, respectively). Hierarchical Linear Modelling (HLM) revealed that, on a sample-wide level, there was no evidence of a relationship between total amygdala volume, or the volume of the right or left hemisphere amygdala taken separately, and cortisol reactivity. Unexpectedly, for PND offspring, larger right hemisphere amygdala volume was associated with lower cortisol reactivity in response to stress, an effect that was not apparent in control offspring. We conclude that the relationship between amygdala volumes and stress reactivity may not be as clear as previous models suggested

The SFA Business Review Vol. 2 No. 1

https://scholarworks.sfasu.edu/busreview/1002/thumbnail.jp

Phi Mesons from a Hadronic Fireball

Production of $\phi$ mesons is considered in the course of heavy-ion collisions at SPS energies. We investigate the possible difference in momentum distributions of $\phi$ mesons measured via their leptonic ($\mu^+\mu^-$) and hadronic ($K^+K^-$) decays. Rescattering of secondary kaons in the dense hadron gas together with the influence of in-medium kaon potential can lead to a relative decrease of a $\phi$ yield observed in the hadronic channel. We analyze how the in-medium modifications of meson properties affect apparent - reconstructed momentum distributions of $\phi$ mesons. Quantitative results are presented for central Pb+Pb collisions at $E_{beam}=158 GeV/A$.Comment: style Revtex4,9 pages, 5 figures. submitted to Phys. Rev.

The CP-conserving two-Higgs-doublet model: the approach to the decoupling limit

A CP-even neutral Higgs boson with Standard-Model-like couplings may be the lightest scalar of a two-Higgs-doublet model. We study the decoupling limit of the most general CP-conserving two-Higgs-doublet model, where the mass of the lightest Higgs scalar is significantly smaller than the masses of the other Higgs bosons of the model. In this case, the properties of the lightest Higgs boson are nearly indistinguishable from those of the Standard Model Higgs boson. The first non-trivial corrections to Higgs couplings in the approach to the decoupling limit are also evaluated. The importance of detecting such deviations in precision Higgs measurements at future colliders is emphasized. We also clarify the case in which a neutral Higgs boson can possess Standard-Model-like couplings in a regime where the decoupling limit does not apply. The two-Higgs-doublet sector of the minimal supersymmetric model illustrates many of the above features.Comment: 54 pages, 2 tables, revtex4 format, some new material added (including elegant forms for the three-Higgs and four-Higgs couplings) and typographical errors fixe

The Role of Thailand in the International Trade in CITES-Listed Live Reptiles and Amphibians

BACKGROUND: International wildlife trade is one of the leading threats to biodiversity conservation. The Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) is the most important initiative to monitor and regulate the international trade of wildlife but its credibility is dependent on the quality of the trade data. We report on the performance of CITES reporting by focussing on the commercial trade in non-native reptiles and amphibians into Thailand as to illustrate trends, species composition and numbers of wild-caught vs. captive-bred specimens. METHODOLOGY/PRINCIPAL FINDINGS: Based on data in the WCMC-CITES trade database, we establish that a total of 75,594 individuals of 169 species of reptiles and amphibians (including 27 globally threatened species) were imported into Thailand in 1990-2007. The majority of individuals (59,895, 79%) were listed as captive-bred and a smaller number (15,699, 21%) as wild-caught. In the 1990s small numbers of individuals of a few species were imported into Thailand, but in 2003 both volumes and species diversity increased rapidly. The proportion of captive-bred animals differed greatly between years (from 0 to >80%). Wild-caught individuals were mainly sourced from African countries, and captive-bred individuals from Asian countries (including from non-CITES Parties). There were significant discrepancies between exports and imports. Thailand reports the import of >10,000 individuals (51 species) originating from Kazakhstan, but Kazakhstan reports no exports of these species. Similar discrepancies, involving smaller numbers (>100 individuals of 9 species), can be seen in the import of reptiles into Thailand via Macao. CONCLUSION/SIGNIFICANCE: While there has been an increase in imports of amphibian and reptiles into Thailand, erratic patterns in proportions of captive-bred specimens and volumes suggests either capricious markets or errors in reporting. Large discrepancies with respect to origin point to misreporting or possible violations of the rules and intentions of CITES

A Reservoir Species for the Emerging Amphibian Pathogen Batrachochytrium dendrobatidis Thrives in a Landscape Decimated by Disease

Chytridiomycosis, a disease caused by the fungal pathogen Batrachochytrium dendrobatidis (Bd), is driving amphibian declines and extinctions in protected areas globally. The introduction of invasive reservoir species has been implicated in the spread of Bd but does not explain the appearance of the pathogen in remote protected areas. In the high elevation (>1500 m) Sierra Nevada of California, the native Pacific chorus frog, Pseudacris regilla, appears unaffected by chytridiomycosis while sympatric species experience catastrophic declines. We investigated whether P. regilla is a reservoir of Bd by comparing habitat occupancy before and after a major Bd outbreak and measuring infection in P. regilla in the field, monitoring susceptibility of P. regilla to Bd in the laboratory, examining tissues with histology to determine patterns of infection, and using an innovative soak technique to determine individual output of Bd zoospores in water. Pseudacris regilla persists at 100% of sites where a sympatric species has been extirpated from 72% in synchrony with a wave of Bd. In the laboratory, P. regilla carried loads of Bd as much as an order of magnitude higher than loads found lethal to sympatric species. Histology shows heavy Bd infection in patchy areas next to normal skin, a possible mechanism for tolerance. The soak technique was 77.8% effective at detecting Bd in water and showed an average output of 68 zoospores per minute per individual. The results of this study suggest P. regilla should act as a Bd reservoir and provide evidence of a tolerance mechanism in a reservoir species

Formation of dense partonic matter in relativistic nucleus-nucleus collisions at RHIC: Experimental evaluation by the PHENIX collaboration

Extensive experimental data from high-energy nucleus-nucleus collisions were recorded using the PHENIX detector at the Relativistic Heavy Ion Collider (RHIC). The comprehensive set of measurements from the first three years of RHIC operation includes charged particle multiplicities, transverse energy, yield ratios and spectra of identified hadrons in a wide range of transverse momenta (p_T), elliptic flow, two-particle correlations, non-statistical fluctuations, and suppression of particle production at high p_T. The results are examined with an emphasis on implications for the formation of a new state of dense matter. We find that the state of matter created at RHIC cannot be described in terms of ordinary color neutral hadrons.Comment: 510 authors, 127 pages text, 56 figures, 1 tables, LaTeX. Submitted to Nuclear Physics A as a regular article; v3 has minor changes in response to referee comments. Plain text data tables for the points plotted in figures for this and previous PHENIX publications are (or will be) publicly available at http://www.phenix.bnl.gov/papers.htm

Thermal charm production by massive gluons and quarks

We investigate charm production in an equilibrated quark-gluon plasma produced in heavy-ion collisions at RHIC and LHC. Effective quark and gluon masses are introduced from thermal QCD calculations. Assuming a Bjorken-type longitudinal expansion and including the influence of temperature dependent masses on the expansion, we determine the total number of c\bar{c} pairs produced in the quark-gluon plasma phase. We calculate the charm production rate at leading order with massive gluons and quarks and compare our result to charm production by massless partons. We consider two different scenarios for the initial conditions, a parton gas with a rather long kinetic equilibration time and a minijet gas with a short equilibration time. In a parton gas, assuming m_c=1.2 GeV, we obtain a substantial enhancement over the thermal charm rate from massless quarks and gluons, up to 4.9 secondary charm quark pairs in Au+Au collisions at RHIC and 245 charm pairs in Pb+Pb collisions at the LHC.Comment: 19 pages in Latex and 9 Postscript figure