Evaluation of Skylab photography for water resources, San Luis Valley, Colorado

The author has identified the following significant results. Skylab S190A photography used in a stereo mode is sufficient for defining the drainage divides and drainage patterns at the regional level. This data, combined with geologic information, define the boundaries and distribution of ground water recharge and discharge areas within the basin

Teacher and Student Demographics: A Quantitative Study of their Relationship to Urban Student Academic Performance

The purpose of this quantitative study was to determine if statistical significance existed between teacher gender, teacher ethnicity, and student self-reported self-efficacy. The Morgan-Jinks Self-Efficacy Scale (MJSES) survey instrument (1999) was administered to 1,487 fourth and fifth grade students across two urban school districts within New York State. Null hypotheses involving gender, ethnicity, and levels of selfefficacy guided the study. Results of the data analysis revealed statistical significance between fourth grade student’s self-efficacy level and the gender of their teacher as well as statistical significance between fourth grade student’s self-efficacy and the gender and ethnicity of their teacher. Recommendations for institutional leaders include continuing gender specific programming and assigning teachers and support staff to fourth grade classrooms that reflect the gender of the students. Policy recommendations include instituting or continuing culturally responsive education and hiring educators who have experience teaching in culturally and racially diverse classrooms

Efficiency of Xist-mediated silencing on autosomes is linked to chromosomal domain organisation

BACKGROUND: X chromosome inactivation, the mechanism used by mammals to equalise dosage of X-linked genes in XX females relative to XY males, is triggered by chromosome-wide localisation of a cis-acting non-coding RNA, Xist. The mechanism of Xist RNA spreading and Xist-dependent silencing is poorly understood. A large body of evidence indicates that silencing is more efficient on the X chromosome than on autosomes, leading to the idea that the X chromosome has acquired sequences that facilitate propagation of silencing. LINE-1 (L1) repeats are relatively enriched on the X chromosome and have been proposed as candidates for these sequences. To determine the requirements for efficient silencing we have analysed the relationship of chromosome features, including L1 repeats, and the extent of silencing in cell lines carrying inducible Xist transgenes located on one of three different autosomes. RESULTS: Our results show that the organisation of the chromosome into large gene-rich and L1-rich domains is a key determinant of silencing efficiency. Specifically genes located in large gene-rich domains with low L1 density are relatively resistant to Xist-mediated silencing whereas genes located in gene-poor domains with high L1 density are silenced more efficiently. These effects are observed shortly after induction of Xist RNA expression, suggesting that chromosomal domain organisation influences establishment rather than long-term maintenance of silencing. The X chromosome and some autosomes have only small gene-rich L1-depleted domains and we suggest that this could confer the capacity for relatively efficient chromosome-wide silencing. CONCLUSIONS: This study provides insight into the requirements for efficient Xist mediated silencing and specifically identifies organisation of the chromosome into gene-rich L1-depleted and gene-poor L1-dense domains as a major influence on the ability of Xist-mediated silencing to be propagated in a continuous manner in cis

Parasitism and host behavior in the context of a changing environment: The Holocene record of the commercially important bivalve Chamelea gallina, northern Italy

Rapid warming and sea-level rise are predicted to be major driving forces in shaping coastal ecosystems and their services in the next century. Though forecasts of the multiple and complex effects of temperature and sea-level rise on ecological interactions suggest negative impacts on parasite diversity, the effect of long term climate change on parasite dynamics is complex and unresolved. Digenean trematodes are complex life cycle parasites that can induce characteristic traces on their bivalve hosts and hold potential to infer parasite host-dynamics through time and space. Previous work has demonstrated a consistent association between sea level rise and increasing prevalence of trematode traces, but a number of fundamental questions remain unanswered about this paleoecological proxy. Here we examine the relationships of host size, shape, and functional morphology with parasite prevalence and abundance, how parasites are distributed across hosts, and how all of these relationships vary through time, using the bivalve Chamelea gallina from a Holocene shallow marine succession in the Po coastal plain. Trematode prevalence increased and decreased in association with the transition from a wave-influenced estuarine system to a wave-dominated deltaic setting. Prevalence and abundance of trematode pits are associated with large host body size, reflecting ontogenetic accumulation of parasites, but temporal trends in median host size do not explain prevalence trends. Ongoing work will test the roles of temperature, salinity, and nutrient availability on trematode parasitism. Parasitized bivalves in one sample were shallower burrowers than their non-parasitized counterparts, suggesting that hosts of trematodes can be more susceptible to their predators, though the effect is ephemeral. Like in living parasite-host systems, trematode-induced malformations are strongly aggregated among hosts, wherein most host individuals harbor very few parasites while a few hosts have many. We interpret trace aggregation to support the assumption that traces are a reliable proxy for trematode parasitism in the fossil record

Geologic and mineral and water resources investigations in western Colorado, using Skylab EREP data

The author has identified the following significant results. Skylab photographs are superior to ERTS images for photogeologic interpretation, primarily because of improved resolution. Lithologic contacts can be detected consistently better on Skylab S190A photos than on ERTS images. Color photos are best; red and green band photos are somewhat better than color-infrared photos; infrared band photos are worst. All major geologic structures can be recognized on Skylab imagery. Large folds, even those with very gentle flexures, can be mapped accurately and with confidence. Bedding attitudes of only a few degrees are recognized; vertical exaggeration factor is about 2.5X. Mineral deposits in central Colorado may be indicated on Skylab photos by lineaments and color anomalies, but positive identification of these features is not possible. S190A stereo color photography is adequate for defining drainage divides that in turn define the boundaries and distribution of ground water recharge and discharge areas within a basin

Ground water recharge to the aquifers of northern San Luis Valley, Colorado: A remote sensing investigation

The author has identified the following significant results. Ground water recharge to the aquifers of San Luis Valley west of San Luis Creek was primarily from ground water flow in the volcanic aquifers of the San Juan Mountains. The high permeability and anisotropic nature of the volcanic rocks resulted in very little contrast in flow conditions between the San Juan Mountains and San Luis Valley. Ground water recharge to aquifers of eastern San Luis Valley was primarily from stream seepage into the upper reaches of the alluvial fans at the base of the Sangre de Cristo Mountains. The use of photography and thermal infrared imagery resulted in a savings of time and increase in accuracy in regional hydrogeologic studies. Volcanic rocks exhibited the same spectral reflectance curve as sedimentary rocks, with only the absolute magnitude of reflectance varying. Both saline soils and vegetation were used to estimate general ground water depths

Long-Wave Forcing by the Breaking of Random Gravity Waves on a Beach

This paper presents new laboratory data on long-wave (surf-beat) forcing by the random breaking of shorter gravity water waves on a plane beach. The data include incident and outgoing wave amplitudes, together with shoreline oscillation amplitudes at long-wave frequencies, from which the correlation between forced long waves and short-wave groups is examined. A detailed analysis of the cross-shore structure of the long-wave motion is presented, and the observations are critically compared with existing theories for two-dimensional surf-beat generation. The surf beat shows a strong dependency on normalized surf-zone width, consistent with long-wave forcing by a time-varying breakpoint, with little evidence of the release and reflection of incident bound long waves for the random-wave simulations considered. The seaward-propagating long waves show a positive correlation with incident short-wave groups and are linearly dependent on short-wave amplitude. The phase relationship between the incident bound long waves and radiated free long waves is also consistent with breakpoint forcing. In combination with previous work, the present data suggest that the breakpoint variability may be the dominant forcing mechanism during conditions with steep incident short waves

Ambipolar Nernst effect in NbSe2_2

The first study of Nernst effect in NbSe$_2$ reveals a large quasi-particle contribution with a magnitude comparable and a sign opposite to the vortex signal. Comparing the effect of the Charge Density Wave(CDW) transition on Hall and Nernst coefficients, we argue that this large Nernst signal originates from the thermally-induced counterflow of electrons and holes and indicates a drastic change in the electron scattering rate in the CDW state. The results provide new input for the debate on the origin of the anomalous Nernst signal in high-T$_c$ cuprates.Comment: 5 pages including 4 figure

Evaluating shoreline identification using optical satellite images

A technique to extract the shoreline location from optical satellite images has been developed and evaluated for the case study site of Progreso, Yucatán, México. A novel method to extract a satellite-derived shoreline (SDS) was developed ensuring the maximum contrast between sea and land. The area under investigation is an 8. km length of shoreline that faces north into the Gulf of México.The SDS was validated using quasi-simultaneous in situ shoreline measurements, both adjusted to equal water levels. In situ shoreline measurements recorded the instantaneous shoreward extent of the wave run-up when walking along the beach.The validation of SDS revealed that the SDS is located consistently seawards of the in situ shoreline, explained by: a) the water depth that optical satellite image requires to identify a pixel either as sea or land, and b) the shoreward extent of the wave run-up. The overall distance between SDS and in situ shoreline is 5.6. m on average with a standard deviation of 1.37. m (in the horizontal) over 8. km of shoreline. Confidence bounds considering the shoreward extent of the wave run-up, inter-tidal beach slope variation and tidal uncertainty were computed to assess the accuracy of the SDS.The SDS has been shown to be capable of detecting shoreline changes of less than 10. m and abrupt changes due to storms. The success of our method suggests that it should be applicable to other locations, after adapting the confidence bounds to the beach conditions