Enhancement of the Hall-Lorenz number in optimally doped YBa2Cu3O_7-d

Electronic heat transport in the normal state of a high-quality single crystal of optimally-doped superconductor YBa2Cu3O6.95 was studied by measurements of longitudinal and transverse transport coefficients. For the temperature range from 100 to 300 K, the Hall-Lorenz number (Lxy) depends weakly on temperature and is about two times larger than the Sommerfeld value of the Lorenz number Lo = (pi^2)/3. Our results can be interpreted using a Fermi liquid model when effects of the pseudogap that opens at the Fermi level are included. However, we find that the bipolaron model can also explain both the enhanced value and the weak temperature dependence of the Hall-Lorenz number.Comment: Accepted for publication in Europhysics Letters; 16 pages, 2 figure

Evolution of a stream ecosystem in recently deglaciated terrain

Climate change and associated glacial recession create new stream habitat that leads to the assembly of new riverine communities through primary succession. However, there are still very few studies of the patterns and processes of community assembly during primary succession for stream ecosystems. We illustrate the rapidity with which biotic communities can colonize and establish in recently formed streams by examining Stonefly Creek in Glacier Bay, Alaska (USA), which began to emerge from a remnant glacial ice mass between 1976 and 1979. By 2002, 57 macroinvertebrate and 27 microcrustacea species had become established. Within 10 years of the stream's formation, pink salmon and Dolly Varden charr colonized, followed by other fish species, including juvenile red and silver salmon, Coast Range sculpin, and sticklebacks. Stable-isotope analyses indicate that marine-derived nitrogen from the decay of salmon carcasses was substantially assimilated within the aquatic food web by 2004. The findings from Stonefly Creek are compared with those from a long-term study of a similarly formed but older stream (12 km to the northeast) to examine possible similarities in macroinvertebrate community and biological trait composition between streams at similar stages of development. Macroinvertebrate community assembly appears to have been initially strongly deterministic owing to low water temperature associated with remnant ice masses. In contrast, microcrustacean community assembly appears to have been more stochastic. However, as stream age and water temperature increased, macroinvertebrate colonization was also more stochastic, and taxonomic similarity between Stonefly Creek and a stream at the same stage of development was,<50%. However the most abundant taxa were similar, and functional diversity of the two communities was almost identical. Tolerance is suggested as the major mechanism of community assembly. The rapidity with which salmonids and invertebrate communities have become established across an entire watershed has implications for the conservation of biodiversity in freshwater habitats

Expenditure-based segmentation and visitor profiling at The Quays in Salford, UK

There is a substantial body of literature relating to tourism’s economic impact at the macro level, but less is known about tourist expenditure at a micro scale. This paper reports findings from a survey of day-visitor expenditure by category at The Quays in Salford, UK. Expenditure is influenced strongly by the visitor’s age, frequency of visitation and visit motivation. Heavy, medium and light expenditure segments and associated profiles are identified. ‘Heavy spenders’ are more likely to be female, in a family group and have shopping as the main motivation for the visit. The implications of the findings are discussed

Core-level photoemission spectroscopy of nitrogen bonding in GaNxAs1–x alloys

The nitrogen bonding configurations in GaNxAs1–x alloys grown by molecular beam epitaxy with 0.07=0.03, the nitrogen is found to exist in a single bonding configuration – the Ga–N bond; no interstitial nitrogen complexes are present. The amount of nitrogen in the alloys is estimated from the XPS using the N 1s photoelectron and Ga LMM Auger lines and is found to be in agreement with the composition determined by x-ray diffraction

Hydrogen gas and its role in cell signalling

This is the author accepted manuscript. The final version is available from CAB International via the DOI in this record. Hydrogen gas (H2) was once thought to be inert in biological systems but it has now become apparent that exposure of a wide range of organisms, including animals and plants, to H2or hydrogen-rich water has beneficial effects. It is involved in plant development, and alleviation of stress and illness, such as reperfusion injury. Here, an overview of how H2interacts with organisms is given

A millimeter wavelength interferometric study of organic molecules in comet hale-bopp (c/1995 o1)

Observations of comet Hale-Bopp with the BIMA Array were conducted in interferometric and autocorrelation modes in the late winter and early spring of 1997. The following points summarize the highlights of this research project. • The capability of the BIMA Array to detect new cometary molecules has been established, with the discovery of HCO+ in comet Hale-Bopp. • Millimeter wavelength interferometric maps of comet spectral line emission have been made for the first time, proving the concept that comets can be successfully observed with the BIMA Array. • A new technique, the "difference map", has been developed for analyzing high resolution images. This technique provides direct evidence of deviations from spherical outflow. • The full utility of dedicated data transfer links and high speed computers has been exploited, revealing the plausibility of yielding arcsecond level ephemeris corrections on a daily basis. • A three dimensional, non-spherically symmetric Monte Carlo code has been written to calculate production rates, the results of which, when combined with analysis of the high resolution observations and difference maps, have yielded more accurate production rates than those of the standard model.Ope

WE Program Training Manual For Culturally Responsive School-Based Mental Health Practices

An abundance of evidence suggests that K–12 Black Indigenous People of Color (BIPOC) students experience disparities in school-based mental health services and negative school-based outcomes due to racism, discrimination, and biases. Such experiences have deleterious impact on their mental health, academic functioning, and other pre- and post-matriculation outcomes. These dynamics can lead to poor academic functioning and adverse mental health outcomes which can include depression, anxiety, toxic stress, decreased self-worth and self-esteem, and psychological maladjustment. School-Based Mental Health (SBMH) providers that are trained to be culturally responsive are uniquely situated to mitigate these negative events and ensure that BIPOC students have more positive outcomes and gain greater access to mental health services. They can do this by advocating for their needs, conducting culturally appropriate treatment, and providing recommendations to other school stakeholders about being culturally responsive. School-based mental health providers must receive proper training to be culturally responsive and facilitate appropriate and affirming support for this population. Based on a culturally responsive framework and theoretical foundations from Bronfenbrenner’s Socioecological Theory and Social Justice Theory, this manual recommends training SBMH providers to use a robust school-based culturally responsive mental health training program called the WE program that encompasses three main areas. Area one, “Pre-Work,” area two a “16-session culturally therapeutic model” based on CBT and Strength-based approaches, and area three “culturally responsive systemic school recommendations.” All three areas are designed to promote improvement to BIPOC students’ mental health and decrease their K–12 pre- and post-matriculation negative outcomes

Influence of oxygen ordering kinetics on Raman and optical response in YBa_2Cu_3O_{6.4}

Kinetics of the optical and Raman response in YBa_2Cu_3O_{6.4} were studied during room temperature annealing following heat treatment. The superconducting T_c, dc resistivity, and low-energy optical conductivity recover slowly, implying a long relaxation time for the carrier density. Short relaxation times are observed for the B_{1g} Raman scattering -- magnetic, continuum, and phonon -- and the charge transfer band. Monte Carlo simulations suggest that these two relaxation rates are related to two length scales corresponding to local oxygen ordering (fast) and long chain and twin formation (slow).Comment: REVTeX, 3 pages + 4 PostScript (compressed) figure