Dopamine-D1 and δ-opioid receptors co-exist in rat striatal neurons

Cocaine’s enhancement of dopaminergic neurotransmission in the mesolimbic pathway plays a critical role in the initial reinforcing properties of this drug. However, other neurotransmitter systems are also integral to the addiction process. A large body of data indicates that opioids and dopamine together mediate emotional and reinforced behaviors. In support of this, cocaine-mediated increases in activation of dopamine D1 receptors (D1R) results in a desensitization of δ-opioid receptor (DOR) signaling through adenylyl cyclase (AC) in striatal neurons. To further define cellular mechanisms underlying this effect, the subcellular distribution of DOR and D1R was examined in the rat dorsolateral striatum. Dual immunoperoxidase/gold-silver detection combined with electron microscopy was used to identify DOR and D1R immunoreactivities in the same section of tissue. Semi-quantitative analysis revealed that a subset of dendritic cellular profiles exhibited both DOR and D1R immunoreactivities. Of 165 randomly sampled D1R immunoreactive profiles, 43% contained DOR. Similarly of 198 DOR-labeled cellular profiles, 52% contained D1R. The present data provide ultrastructural evidence for co-existence between DOR and D1R in striatal neurons, suggesting a possible mechanism whereby D1R modulation may alter DOR function

Age-Related Needs of Community College Students

The literature of adult education commonly suggests that older learners have a distinct set of needs and a unique mode of learning that ought to be honoured by educational institutions; other observers note that education is a process whose generic elements are not age-related. Capilano College, with a strong com- mitment to mature learners as part of its community orientation, surveyed its student population by age grouping to determine the extent to which significant, substantive differences in the self-perceived needs of different age groupings were evident. The survey revealed that, although there were several distinguishing characteristics between students below and above age 25, younger and older students share a large common set of needs; older students seem to have a greater number of needs and appear to feel them more acutely.Généralement, la documentation sur l'éducation permanente semble indiquer que les étudiants adultes éprouvent des besoins distincts et possèdent un mode d'apprentissage qui leur est particulier et dont les institutions d'enseignement devraient tenir compte. D'autres observateurs remarquent que l'instruction est un processus dont les éléments génériques n'ont rien à voir avec le facteur-âge. Le Collège Capilano dans la poursuite de son engagement envers les étudiants adultes et envers la communauté qu'il dessert a fait une étude de sa population étudiante par groupe d'âge afin de déterminer dans quelle mesure il y avait évidence de différences significatives dans les besoins perçus par les différents groupes d'âges. L'étude a révélé que malgré certaines caractéristiques particu-lières aux étudiants de moins et de plus de 25 ans, la population étudiante en général éprouve des besoins communs. Les étudiants adultes paraissent éprouver un plus grand nombre de besoins et semblent les ressentir plus vivement

Long-range potentials and (n−1)d+ns(n-1)d+ns molecular resonances in an ultracold rydberg gas

We have calculated long-range molecular potentials of the $0_g^{+}$, $0_u^{-}$ and $1_u$ symmetries between highly-excited rubidium atoms. Strong $np+np$ potentials characterized by these symmetries are important in describing interaction-induced phenomena in the excitation spectra of high $np$ Rydberg states. Long-range molecular resonances are such phenomena and they were first reported in S.M. Farooqi {\it et al.}, Phys. Rev. Lett. {\bf 91} 183002. One class of these resonances occurs at energies corresponding to excited atom pairs $(n-1)d+ns$. Such resonances are attributed to $\ell$-mixing due to Rydberg-Rydberg interactions so that otherwise forbidden molecular transitions become allowed. We calculate molecular potentials in Hund's case (c), use them to find the resonance lineshape and compare to experimental results.Comment: 11 pages, 7 figure

Exploring X-ray Binary Populations in Compact Group Galaxies with ChandraChandra

We obtain total galaxy X-ray luminosities, $L_X$, originating from individually detected point sources in a sample of 47 galaxies in 15 compact groups of galaxies (CGs). For the great majority of our galaxies, we find that the detected point sources most likely are local to their associated galaxy, and are thus extragalactic X-ray binaries (XRBs) or nuclear active galactic nuclei (AGNs). For spiral and irregular galaxies, we find that, after accounting for AGNs and nuclear sources, most CG galaxies are either within the $\pm1\sigma$ scatter of the Mineo et al. (2012) $L_X$ - star formation rate (SFR) correlation or have higher $L_X$ than predicted by this correlation for their SFR. We discuss how these "excesses" may be due to low metallicities and high interaction levels. For elliptical and S0 galaxies, after accounting for AGNs and nuclear sources, most CG galaxies are consistent with the Boroson et al. (2011) $L_X$ - stellar mass correlation for low-mass XRBs, with larger scatter, likely due to residual effects such as AGN activity or hot gas. Assuming non-nuclear sources are low- or high-mass XRBs, we use appropriate XRB luminosity functions to estimate the probability that stochastic effects can lead to such extreme $L_X$ values. We find that, although stochastic effects do not in general appear to be important, for some galaxies there is a significant probability that high $L_X$ values can be observed due to strong XRB variability.Comment: Accepted by Ap

Interactions Between Rydberg-Dressed Atoms

We examine interactions between atoms continuously and coherently driven between the ground state and a Rydberg state, producing "Rydberg-dressed atoms." Because of the large dipolar coupling between two Rydberg atoms, a small admixture of Rydberg character into a ground state can produce an atom with a dipole moment of a few Debye, the appropriate size to observe interesting dipolar physics effects in cold atom systems. We have calculated the interaction energies for atoms that interact via the dipole-dipole interaction and find that due to blockade effects, the R-dependent two-atom interaction terms are limited in size, and can be R-independent up until the dipolar energy is equal to the detuning. This produces R-dependent interactions different from the expected 1/R^3 dipolar form, which have no direct analogy in condensed matter physics, and could lead to new quantum phases in trapped Rydberg systems.Comment: 5 pages, 7 figures; Accepted to Phys. Rev. A, 18 Aug. 201

The Effects of Age on Red Giant Metallicities Derived from the Near-Infrared Ca II Triplet

We have obtained spectra with resolution 2.5 Angstroms in the region 7500-9500 Angstroms for 116 red giants in 5 Galactic globular clusters and 6 old open clusters (5 with published metallicities, and one previously unmeasured). The signal-to-noise ranges from 20 to 85. We measure the equivalent widths of the infrared Ca II triplet absorption lines in each stars and compare to cluster metallicities taken from the literature. With globular cluster abundances on the Carretta & Gratton scale, and open cluster abundances taken from the compilation of Friel and collaborators, we find a linear relation between [Fe/H] and Ca II line strength spanning the range -2 < [Fe/H] < -0.2 and ages from 2.5 - 13 Gyr. No evidence for an age effect on the metallicity calibration is observed. Using this calibration, we find the metallicity of the old open cluster Trumpler 5 to be [Fe/H] = -0.56 +/-0.11. Considering the 10 clusters of known metallicity shifted to a common distance and reddening, we find that the additional metallicity error introduced by the variation of horizontal branch/red clump magnitude with metallicity and age is of order +/-0.05 dex, which can be neglected in comparison to the intrinsic scatter in our method. The results are discussed in the context of abundance determinations for red giants in Local Group galaxies.Comment: Accepted by MNRAS; 21 pages in LaTeX MNRAS style, 6 tables, 6 figure

Yosemite Conference on Ionospheric Plasma in the Magnetosphere: Sources, Mechanisms and Consequences, meeting report

The sixth biennial Yosemite topical conference and the first as a Chapman Conference was held on February 3 to 6, 1986. Due to the recent changes in our perception of the dynamics of the ionospheric/magnetospheric system, it was deemed timely to bring researchers together to discuss and contrast the relative importance of solar versus terrestrial sources of magnetospheric plasma. Although the solar wind was once thought to dominate the supply of plasma in the Earth's magnetosphere, it is now thought that the Earth's ionosphere is a significant contributor. Polar wind and other large volume outflows of plasma have been seen at relatively high altitudes over the polar cap and are now being correlated with outflows found in the magnetotail. The auroral ion fountain and cleft ion fountain are examples of ionospheric sources of plasma in the magnetosphere, observed by the Dynamics Explorer 1 (DE 1) spacecraft. The conference was organized into six sessions: four consisting of prepared oral presentations, one poster session, and one session for open forum discussion. The first three oral sessions dealt separately with the three major topics of the conference, i.e., the sources, mechanisms, and consequences of ionospheric plasma in the magnetosphere. A special session of invited oral presentations was held to discuss extraterrestrial ionospheric/magnetospheric plasma processes. The poster session was extended over two evenings during which presenters discussed their papers on a one-on-one basis. The last session of the conferences was reserved for open discussions of those topics or ideas considered most interesting or controversial

NGC 602 Environment, Kinematics and Origins

The young star cluster NGC 602 and its associated HII region, N90, formed in a relatively isolated and diffuse environment in the Wing of the Small Magellanic Cloud. Its isolation from other regions of massive star formation and the relatively simple surrounding HI shell structure allows us to constrain the processes that may have led to its formation and to study conditions leading to massive star formation. We use images from Hubble Space Telescope and high resolution echelle spectrographic data from the Anglo-Australian Telescope along with 21-cm neutral hydrogen (HI) spectrum survey data and the shell catalogue derived from it to establish a likely evolutionary scenario leading to the formation of NGC 602. We identify a distinct HI cloud component that is likely the progenitor cloud of the cluster and HII region which probably formed in blister fashion from the cloud's periphery. We also find that the past interaction of HI shells can explain the current location and radial velocity of the nebula. The surrounding Interstellar Medium is diffuse and dust-poor as demonstrated by a low visual optical depth throughout the nebula and an average HI density of the progenitor cloud estimated at 1 cm^-3. These conditions suggest that the NGC 602 star formation event was produced by compression and turbulence associated with HI shell interactions. It therefore represents a single star forming event in a low gas density region.Comment: Accepted for publication in PASP. 25 pages, 10 figure

Chemical composition of a sample of bright solar-metallicity stars

We present a detailed analysis of seven young stars observed with the spectrograph SOPHIE at the Observatoire de Haute-Provence for which the chemical composition was incomplete or absent in the literature. For five stars, we derived the stellar parameters and chemical compositions using our automatic pipeline optimized for F, G, and K stars, while for the other two stars with high rotational velocity, we derived the stellar parameters by using other information (parallax), and performed a line-by-line analysis. Chromospheric emission-line fluxes from CaII are obtained for all targets. The stellar parameters we derive are generally in good agreement with what is available in the literature. We provide a chemical analysis of two of the stars for the first time. The star HIP 80124 shows a strong Li feature at 670.8 nm implying a high lithium abundance. Its chemical pattern is not consistent with it being a solar sibling, as has been suggested.Comment: To be published on A