Massive Lyman Break Galaxies at z~3 in the Spitzer Extragalactic First Look Survey

We investigate the properties of 1088 Lyman Break Galaxies (LBGs) at z~3 selected from a ~2.63$deg2 sub-region of the First Look Survey field using the ground-based multi-color data and the Spitzer Space Telescope mid-infrared data at 3--8 and 24 um. With the wide area and the broad wavelength coverage, we sample a large number of ``rare'' u-band dropouts which are massive (M* > 10^11 Msun), allowing us to perform a statistical analysis of these subsets of LBGs that have not been studied in detail. Optically bright (R(AB) < 24.5 mag) LBGs detected in mid-infrared (S_{3.6um} > 6 uJy) reside at the most massive and dusty end of the LBG population, with relatively high and tight$M/L$ in rest-frame near-infrared. Most infrared-luminous LBGs (S_{24um} > 100 uJy) are dusty star-forming galaxies with star formation rates of 100--1000 Msun/yr, total infrared luminosity of > 10^12 Lsun. By constructing the UV luminosity function of massive LBGs, we estimate that the lower limit for the star formation rate density from LBGs more massive than 10^11 Msun at z~3 is > 3.3 x 10^-3 Msun/yr/Mpc^3, showing for the first time that the UV-bright population of massive galaxies alone contributes significantly to the global star formation rate density at z~3. When combined with the star formation rate densities at z < 2, our result reveals a steady increase in the contribution of massive galaxies to the global star formation from z=0 to z=3, providing strong support to the downsizing of galaxy formation.Comment: 15 pages, 13 figures. Accepted for publication in Ap

Central Corneal Thickness: A Retrospective Comparison of Handheld Ultrasound Pachymetry and Optical Biometric Analysis Measurements

Purpose To determine if the measure of central cornea thickness among suspected and confirmed glaucomatous patients is significantly influenced by instrument device. Methods We retrospectively examined the charts of all patients having a central corneal thickness (CCT) measured with both ultrasound pachymetry and IOL Master 700 at the Kresge Eye Institute within the past year. Intraocular pressure and demographic data including age and race, were also collected. Significant corneal disease such as Fuchs corneal dystrophy, other corneal dystrophies, corneal transplant, and corneal edema were excluded. Statistical analysis of the paired CCT measurements were performed with a paired t-test and regression analysis. Results The total number of patients having a CCT measured with both ultrasound pachymetry and IOLMaster700 was 59. Mean CCT measured with ultrasound pachymetry was 539.38 ± 49.56 µm (n=118). Mean CCT measured with IOLMaster700 was 536.83 ± 42.52 µm (n=112). The intraparticipant mean of differences between the ultrasound pachymetry and the IOLMaster700 was 3.16 ± 25 µm. Analysis with a paired t-test did not find a significant difference between the two groups (p=0.19). A regression analysis of the paired CCTs yielded an R2 value of 0.74. Conclusion There is no significant difference between CCT measurements taken with handheld ultrasound pachymetry compared to the IOL Master 700. More data is warranted to confirm, but the IOL Master 700 may yield lower variability and a lower mean CCT, possibly due to greater instrument precision and increased likelihood of a central measurement. In practice, the IOL Master 700 may provide a more reliable measure of central cornea thickness when compared with ultrasound pachymetry

On the Continuous Formation of Field Spheroidal Galaxies in Hierarchical Models of Structure Formation

We re-examine the assembly history of field spheroidals as a potentially powerful discriminant of galaxy formation models. Whereas monolithic collapse and hierarchical, merger-driven, models suggest radically different histories for these galaxies, neither the theoretical predictions nor the observational data for field galaxies have been sufficiently reliable for precise conclusions to be drawn. A major difficulty in interpreting the observations, reviewed here, concerns the taxonomic definition of spheroidals in merger-based models. Using quantitative measures of recent star formation activity drawn from the internal properties of a sample of distant field galaxies in the Hubble Deep Fields, we undertake a new analysis to assess the continuous formation of spheroidal galaxies. Whereas abundances and redshift distributions of modelled spheroidals are fairly insensitive to their formation path, we demonstrate that the distribution and amount of blue light arising from recent mergers provides a more sensitive approach. With the limited resolved data currently available, the rate of mass assembly implied by the observed colour inhomogeneities is compared to that expected in popular Lambda-dominated cold dark matter models of structure formation. These models produce as many highly inhomogeneous spheroidals as observed, but underpredict the proportion of homogeneous, passive objects. We conclude that colour inhomogeneities, particularly when combined with spectroscopic diagnostics for large, representative samples of field spheroidals, will be a more valuable test of their physical assembly history than basic source counts and redshift distributions. Securing such data should be a high priority for the Advanced Camera for Surveys on Hubble Space Telescope.Comment: 14 pages, 7 figures, submitted to MNRA

Evaluation of a standard provision versus an autonomy promotive exercise referral programme: rationale and study design

Background The National Institute of Clinical Excellence in the UK has recommended that the effectiveness of ongoing exercise referral schemes to promote physical activity should be examined in research trials. Recent empirical evidence in health care and physical activity promotion contexts provides a foundation for testing the utility of a Self Determination Theory (SDT) -based exercise referral consultation. Methods/Design Design: An exploratory cluster randomised controlled trial comparing standard provision exercise on prescription with a Self Determination Theory-based (SDT) exercise on prescription intervention. Participants: 347 people referred to the Birmingham Exercise on Prescription scheme between November 2007 and July 2008. The 13 exercise on prescription sites in Birmingham were randomised to current practice (n=7) or to the SDT-based intervention (n=6). Outcomes measured at 3 and 6-months: Minutes of moderate or vigorous physical activity per week assessed using the 7-day Physical Activity Recall; physical health: blood pressure and weight; health status measured using the Dartmouth CO-OP charts; anxiety and depression measured by the Hospital Anxiety and Depression Scale and vitality measured by the subjective vitality score; motivation and processes of change: perceptions of autonomy support from the advisor, satisfaction of the needs for competence, autonomy, and relatedness via physical activity, and motivational regulations for exercise. Discussion This trial will determine whether an exercise referral programme based on Self Determination Theory increases physical activity and other health outcomes compared to a standard programme and will test the underlying SDT-based process model (perceived autonomy support, need satisfaction, motivation regulations, outcomes) via structural equation modelling. Trial registration The trial is registered as Current Controlled trials ISRCTN07682833

Vegetation Cover Analysis of Hazardous Waste Sites in Utah and Arizona Using Hyperspectral Remote Sensing

This study investigated the usability of hyperspectral remote sensing for characterizing vegetation at hazardous waste sites. The specific objectives of this study were to: (1) estimate leaf-area-index (LAI) of the vegetation using three different methods (i.e., vegetation indices, red-edge positioning (REP), and machine learning regression trees), and (2) map the vegetation cover using machine learning decision trees based on either the scaled reflectance data or mixture tuned matched filtering (MTMF)-derived metrics and vegetation indices. HyMap airborne data (126 bands at 2.3 x 2.3 m spatial resolution), collected over the U. S. Department of Energy uranium processing sites near Monticello, Utah and Monument Valley, Arizona, were used. Grass and shrub species were mixed on an engineered disposal cell cover at the Monticello site while shrub species were dominant in the phytoremediation plantings at the Monument Valley site. Regression trees resulted in the best calibration performance of LAI estimation (R-2 > 0.80. The use of REPs failed to accurately predict LAI (R-2 < 0.2). The use of the MTMF-derived metrics (matched filter scores and infeasibility) and a range of vegetation indices in decision trees improved the vegetation mapping when compared to the decision tree classification using just the scaled reflectance. Results suggest that hyperspectral imagery are useful for characterizing biophysical characteristics (LAI) and vegetation cover on capped hazardous waste sites. However, it is believed that the vegetation mapping would benefit from the use of higher spatial resolution hyperspectral data due to the small size of many of the vegetation patches (<1 m) found on the sites.open111

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Diffusive Release of Photosensitizing Agents (PS) from Novel PVA-Borate Semi-Solid Drug Carriers Through In Vitro Oral Streptococcus mutans Biofilm

Background: Streptococcus mutans, one of the agent of human dental caries, is particularly effective at forming biofilms on the hard tissues of the human oral cavity; the purpose of this study was to investigate and quantify the diffusional release of photosentising agents (PS): methylene blue (MB), toludine blue (TB), rose bengal (RB) and methyl orange (MO) from Polyvinyl alcohol (PVA)-borate semi-solid gels in the presence of in vitro oral Streptococcus mutans biofilm. Methods: S. mutans biofilm growths were ascertained to ensure proper dental plaque formation and were characterized using confocal microscopy. Release profiles for MB, TB, RB and MO-loaded PVA-borate semi-solids in the absence of biofilms were directly compared to their counterparts in the presence of S. mutans biofilms. In addition, their diffusion coefficients and resistances were determined. Results: The confocal imaging results showed that biofilms grown over a 5-day period had a generally uninterrupted film of colonies occupying the entire surface area of growth surface of a nylon mesh support with approximately 60 µm biofilm size. The overall diffusion resistance of all PVA-borate semi-solids in the presence of S. mutans biofilms was about 1.2 times lower than the diffusion resistance for PVAborate semi-solids in the absence of biofilms. The diffusion resistances for all studied PS, indicate that electrostatic forces and molecular size play an important part in controlled and sustained drug release from PVA-borate semi-solids. Conclusions: PVA-borate semi-solids as novel PSs carriers might offer an innovative delivery system in the treatment against Streptococcus mutans

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