Optical Selection of Galaxies at Redshifts 1<z<3

Few galaxies have been found between the redshift ranges z < ~1 probed by magnitude-limited surveys and z > ~3 probed by Lyman-break surveys. Comparison of galaxy samples at lower and higher redshift suggests that large numbers of stars were born and the Hubble sequence began to take shape at the intermediate redshifts 1<z<3, but observational challenges have prevented us from observing the process in much detail. We present simple and efficient strategies that can be used to find large numbers of galaxies throughout this important but unexplored redshift range. All the strategies are based on selecting galaxies for spectroscopy on the basis of their colors in ground-based images taken through a small number of optical filters: GRi for redshifts 0.85<z<1.15, GRz for 1<z<1.5, and UGR for 1.4<z<2.1 and 1.9<z<2.7. The performance of our strategies is quantified empirically through spectroscopy of more than 2000 galaxies at 1<z<3.5. We estimate that more than half of the UV-luminosity density at 1<z<3 is produced by galaxies that satisfy our color-selection criteria. Our methodology is described in detail, allowing readers to devise analogous selection criteria for other optical filter sets.Comment: 13 pages including 20 figures. Accepted for publication in the Ap

Variability in Ultrasound Education among Emergency Medicine Residencies

Objective: Education in emergency ultrasound (EUS) has become an essential part of emergency medicine (EM) resident training. In 2009, comprehensive residency training guidelines were published to ensure proficiency in ultrasound education. The American College of Emergency Physicians (ACEP) recommends that 150 ultrasound exams be performed for physician competency. Our goal is to evaluate the current ultrasound practices among EM residency programs and assess the need for further formalization of EUS training.Methods: We generated a survey using an online survey tool and administered via the internet. The survey consisted of 25 questions that included multiple choice and free text answers. These online survey links were sent via email to EM ultrasound directors at all 149 American College of Graduate Medical Education EM residency programs in April 2008. We surveyed programs regarding EUS curriculum and residency proficiency requirements and descriptive statistics were used to report the survey findings.Results: Sixty-five residency programs responded to the survey. The average number of ultrasound exams required by programs for EUS competency was 137 scans. However, the majority of programs 42/65 (64%) require their residents to obtain 150 scans or greater for competency. Fifty-one out of 64 (79%) programs reported having a structured ultrasound curriculum while 14/64 (21%) of programs reported that EUS training is primarily resident self-directed. In terms of faculty credentialing, 29/62 (47%) of residency programs have greater than 50% of faculty credentialed. Forty-four out of 61 (72%) programs make EUS a required rotation. Thirty-four out of 63 (54%) programs felt that they were meeting all their goals for resident EUS education.Conclusion: Currently discrepancies exist between EM residency programs in ultrasound curriculum and perceived needs for achieving proficiency in EUS. Although a majority of residency programs require 150 ultrasound exams or more to achieve resident competency, overall the average number of scans required by all programs is 137 exams. This number is less than that recommended by ACEP for physician competency. These data suggest that guidelines are needed to help standardize ultrasound training for all EM residency programs. [West J Emerg Med 2010; 11(4):314-318.

New Observations of the Interstellar Medium in the Lyman Break Galaxy MS 1512-cB58

We present the results of a detailed study of the interstellar medium of MS 1512-cB58, an L* Lyman break galaxy at z = 2.7276, based on new spectral observations obtained with the Echelle Spectrograph and Imager on the Keck II telescope at 58 km/s resolution. We focus in particular on the chemical abundances and kinematics of the interstellar gas and our main findings are as follows. Even at this relatively early epoch, the ISM of this galaxy is already highly enriched in elements released by Type II supernovae; the abundances of O, Mg, Si, P, and S are all about 2/5 of their solar values. In contrast, N and the Fe-peak elements Mn, Fe, and Ni are underabundant by a factor of about 3. Based on current ideas of stellar nucleosynthesis, these results can be understood if most of the metal enrichment in cB58 has taken place within the last 300 million years, the timescale for the release of N from intermediate mass stars. cB58 appears to be an example of a galaxy in the process of converting its gas into stars on a few dynamical timescales; quite possibly we are witnessing the formation of a galactic bulge or an elliptical galaxy. The energetic star formation activity has stirred the interstellar medium to high velocities of up to 1000 km/s. The net effect is a bulk outflow of the ISM at a speed of 255 km/s and at a rate which exceeds the star formation rate. It is unclear whether this gas will be lost or retained by the galaxy. We point out that the chemical and kinematic properties of cB58 are markedly different from those of most damped Lyman alpha systems at the same redshift.Comment: 38 pages, LaTeX, 9 Postscript Figures. Accepted for publication in the Astrophysical Journal. Sections 3.3 and 5.3 expanded, and two additional figures included, following referee's repor

The faint end of the QSO luminosity function at z=3

We present the first measurement of the faint end of the QSO luminosity function at z=3. The QSOs, which range from M_1450 = -21 to M_1450 = -27, were discovered in 17 fields totaling 0.43 deg^2 using multicolor selection criteria (the Lyman break technique) and spectroscopic followup. We find that the faint-end slope of the luminosity function is beta_l=1.24 +/- 0.07, flatter than the value of beta_l=1.64 +/- 0.18 measured at lower redshift. The integrated rest 1450 A UV luminosity of z=3 QSOs is only 50% of most previous estimates, and is only ~8% of that produced by Lyman break galaxies at the same redshifts. Assuming that ionizing photons from faint QSOs are as successful in escaping their host galaxies as bright QSOs, we estimate the total contribution of QSOs to the ionizing flux J_912 at z=3, J_912=2.4*10^-22 ergs/s/cm^2/Hz. This estimate, which we regard as an upper limit, remains consistent with rough estimates of J_912 based on the Lyman-alpha forest "proximity effect."Comment: 14 pages, 3 figures, accepted for publication in the Astrophysical Journa

A Survey of Star-Forming Galaxies in the z=1.4-2.5 `Redshift Desert': Overview

We present the first results of a large-scale survey, using the UV/blue sensitive LRIS-B spectrograph on the Keck I telescope, of galaxies in the redshift interval 1.4<z<2.5, often called the `redshift desert' because of historical difficulties in spectroscopically identifying galaxies in that range. We introduce two samples of star forming galaxies, `BX' galaxies at =2.20+/-0.32 and `BM' galaxies at =1.70+/-0.34; currently we have spectroscopically confirmed 749 of the former and 114 of the latter. We also present initial results of deep near-IR photometry and spectroscopy, from which we show that z~2 galaxies are significantly redder in their optical/IR colors compared to similarly UV-selected galaxies at z~3, but that the characteristics of their galaxy-scale outflows are quite similar. We illustrate by example the information which can be deduced on the stellar populations, metallicities, and kinematics of `redshift desert' galaxies from easily accessible rest-frame far-UV and rest-frame optical spectra. Far from being hostile to observations, the universe at z~2 is uniquely suited to providing information on the astrophysics of star-forming galaxies and the intergalactic medium, and the relationship between the two [abridged].Comment: To appear in ApJ, April 2004. 16 pages, uses emulateap

Rapa Nui (Easter Island) monument (ahu) locations explained by freshwater sources

Explaining the processes underlying the emergence of monument construction is a major theme in contemporary anthropological archaeology, and recent studies have employed spatially-explicit modeling to explain these patterns. Rapa Nui (Easter Island, Chile) is famous for its elaborate ritual architecture, particularly numerous monumental platforms (ahu) and statuary (moai). To date, however, we lack explicit modeling to explain spatial and temporal aspects of monument construction. Here, we use spatially-explicit point-process modeling to explore the potential relations between ahu construction locations and subsis- tence resources, namely, rock mulch agricultural gardens, marine resources, and freshwa- ter sources—the three most critical resources on Rapa Nui. Through these analyses, we demonstrate the central importance of coastal freshwater seeps for precontact populations. Our results suggest that ahu locations are most parsimoniously explained by distance from freshwater sources, in particular coastal seeps, with important implications for community formation and inter-community competition in precontact times

Yield Losses and Control by Sedaxane and Fludioxonil of Soilborne Rhizoctonia, Microdochium, and Fusarium Species in Winter Wheat

Soilborne Rhizoctonia, Microdochium, and Fusarium species are major causal agents of seedling and stem-base diseases of wheat. Currently, seed treatments are considered the most effective solution for their control. Rhizoctonia solani anastomosis groups (AGs) 2-1 and 5, R. cerealis, Microdochium, and Fusarium spp., were used in series of field experiments to determine their capability to cause soilborne and stem-base disease and to quantify their comparative losses in the establishment and yield of wheat. The effectiveness and response to seed treatment formulated with 10 g sedaxane and 5 g fludioxonil 100 kg21 against these soilborne pathogens were also determined. Our results showed that damping-off caused by soilborne R. cerealis was associated with significant reductions in the emergence and establishment, resulting in stunted growth and low plant numbers. The pathogen also caused sharp eyespot associated with reductions in the ear partitioning index. R. solani AG 2-1 and AG 5 were weakly pathogenic and failed to cause significant damping-off, root rot, and stem-base disease in wheat. Fusarium graminearum and F. culmorum applied as soilborne inoculum failed to cause severe disease. Microdochium spp. caused brown foot rot disease and soilborne M. nivale reduced wheat emergence. Applications of sedaxane and fludioxonil increased plant emergence and reduced damping-off, early stem-base disease, and brown foot rot, thus providing protection against multiple soilborne pathogens. R. cerealis reduced the thousand grain weight by 3.6%, whereas seed treatment including fludioxonil and sedaxane against soilborne R. cerealis or M. nivale resulted in a 4% yield increase

Spatial and Temporal Scales of Sverdrup Balance

Sverdrup balance underlies much of the theory of ocean circulation and provides a potential tool for describing the interior ocean transport from only the wind stress. Using both a model state estimate and an eddy-permitting coupled climate model, this study assesses to what extent and over what spatial and temporal scales Sverdrup balance describes the meridional transport. The authors find that Sverdrup balance holds to first order in the interior subtropical ocean when considered at spatial scales greater than approximately 5°. Outside the subtropics, in western boundary currents and at short spatial scales, significant departures occur due to failures in both the assumptions that there is a level of no motion at some depth and that the vorticity equation is linear. Despite the ocean transport adjustment occurring on time scales consistent with the basin-crossing times for Rossby waves, as predicted by theory, Sverdrup balance gives a useful measure of the subtropical circulation after only a few years. This is because the interannual transport variability is small compared to the mean transports. The vorticity input to the deep ocean by the interaction between deep currents and topography is found to be very large in both models. These deep transports, however, are separated from upper-layer transports that are in Sverdrup balance when considered over large scales

Infrared cameras overestimate skin temperature during rewarming from cold exposure

This is an accepted manuscript of an article published by Elsevier in Journal of Thermal Biology on 03/05/2020, available online: https://doi.org/10.1016/j.jtherbio.2020.102614 The accepted version of the publication may differ from the final published version.Objective The primary aim of this study was to assess the accuracy of an infrared camera and that of a skin thermistor, both commercially available. The study aimed to assess the agreement over a wide range of skin temperatures following cold exposure. Methods Fifty-two males placed their right hand in a thin plastic bag and immersed it in 8 °C water for 30 min whilst seated in an air temperature of 30 °C. Following hand immersion, participants removed the bag and rested their hand at heart level for 10 min. Index finger skin temperature (Tsk) was measured with a thermistor, affixed to the finger pad, and an infrared camera measured 1 cm distally to the thermistor. Agreement between the infrared camera and thermistor was assessed by mean difference (infrared camera minus thermistor) and 95% limits of agreement analysis, accounting for the repeated measures over time. The clinically significant threshold for Tsk differences was set at ±0.5 °C and limits of agreement ±1 °C. Results As an average across all time points, the infrared camera recorded Tsk 1.80 (SD 1.16) °C warmer than the thermistor, with 95% limits of agreement ranging from −0.46 °C to 4.07 °C. Conclusion Collectively, the results show the infrared camera overestimated Tsk at every time point following local cooling. Further, measurement of finger Tsk from the infrared camera consistently fell outside the acceptable level of agreement (i.e. mean difference exceeding ±0.5 °C). Considering these results, infrared cameras may overestimate peripheral Tsk following cold exposure and clinicians and practitioners should, therefore, adjust their risk/withdrawal criteria accordingly.Published versio

An experimental investigation of the relative strength of the silica polymorphs quartz, coesite and stishovite

In this study, quartz, coesite and stishovite were deformed concurrently with an olivine reference sample at high pressure and 850±50°C. Olivine deformed with an effective stress exponent (n) of 6.0_{+3.1}^{-2.2}, which we interpret to indicate that the Peierls creep deformation mechanism was active in the olivine. Quartz and coesite had very similar strengths and deformed by a mechanism with n = 2.8_{+1.2}^{-0.9} and 2.9_{+1.3}^{-0.9} respectively, which are consistent with previous measurements of power‐law creep in these phases. Stishovite deformed with n = 8.1_{+3.7}^{-2.7} and was stronger than both olivine and the other silica polymorphs. The high stress exponent of stishovite is greater than that typically observed for power‐law creep, indicating it is probably (but not certainly) deforming by Peierls creep. The rheology of SiO₂ minerals appears therefore to be strongly affected by the change in silicon‐coordination and density from 4‐fold in quartz and coesite to 6‐fold in stishovite. If the effect of Si‐coordination can be generalised, the increase in Si‐coordination (and density) associated with bridgmanite formation may explain the 10‐100 fold viscosity increase around 660km depth in the Earth