The Spectra of Star Forming Galaxies at High Redshift

We review the spectral properties of the population of star forming galaxies at z = 3 discovered using a colour selection technique which targets the Lyman discontinuity at 912 Angstroms. The UV luminosity of the typical z = 3 galaxy exceeds by more than one order of magnitude that of the most luminous starbursts in the nearby universe, although the maximum star formation intensity (SFR per unit area) is within the limits found in local surveys. We consider in detail the likely magnitude of dust extinction and conclude that published estimates of the volume-averaged star formation rate at high z need to be revised to higher values by a factor of about 3. This correction improves the agreement between the observations and recent theoretical predictions. Lyman alpha emission is generally weak, most likely as a result of resonant scattering. The large equivalent widths of the strongest interstellar lines and their systematic blueshift (by up to several hundred km/s) relative to the Lyman alpha emission line are indicative of highly energetic outflows in the interstellar medium. Pilot observations have detected the redshifted Hbeta and [O III] emission lines in the K band. The widths of these features imply dynamical masses of approximately 10^{10} solar masses for the innermost star forming regions; the total masses involved are likely to exceed 10^{12} solar masses.Comment: 11 pages, LaTeX, 5 Postscript Figures. To appear in `The Ultraviolet Universe at Low and High Redshift', ed. W. Waller, (Woodbury: AIP Press

Infared Observations of Nebular Emission Lines from Galaxies at z = 3

We present the first results from a program of near-infrared spectroscopy aimed at studying the familiar rest-frame optical emission lines from the H II regions of Lyman break galaxies at z = 3. By targeting redshifts which bring the lines of interest into gaps between the strong OH sky emission, we have been successful in detecting Balmer and [O III] emission lines in all five galaxies observed so far with CGS4 on UKIRT. For a Salpeter IMF and a H_0 = 70 km/s/Mpc, q_0 = 0.1 cosmology, the Hbeta luminosities uncorrected for dust extinction imply star formation rates of 20 - 270 solar masses per year. On the basis of the present limited sample it appears that an extinction of 1 - 2 magnitudes at 1500 A may be typical of Lyman break galaxies. This value is consistent with recent estimates of dust obscuration in star forming galaxies at z < 1, and does not require a substantial revision of the broad picture of star formation over the Hubble time proposed by Madau et al. (1996). In four out of five cases the velocity dispersion of the emission line gas is sigma = 70 km/s, while in the fifth the line widths are nearly three times larger. Virial masses in the range from 1 x 10^{10} to 5 x 10^{10} solar masses are suggested, but both velocities and masses could be higher because our observations are only sensitive to the brightest cores of these systems where the line widths may not sample the full gravitational potential. The relative redshifts of interstellar absorption, nebular emission, and Lyman alpha emission lines differ by several hundred km/s and suggest that large-scale outflows may be a common characteristic of Lyman break galaxies.Comment: 39 pages, LaTeX, 5 Postscript Figures. Accepted for Publication in The Astrophysical Journa

A Large Structure of Galaxies At Redshift z~3 and its Cosmological Implications

We report the discovery of a highly significant concentration of galaxies at a redshift of =3.090. The structure is evident in a redshift histogram of photometrically selected ``Lyman break'' objects in a 9' by 18' field in which we have obtained 78 spectroscopic redshifts in the range 2.0 < z <3.4. The dimensions of the structure projected on the plane of the sky are at least 11'by 8', or 14h_{70}^{-1} by 10h_{70}^{-1} Mpc (comoving; \Omega_M=1). The concentration contains 15 galaxies and one faint (R=21.7) QSO. We consider the structure in the context of a number of cosmological models and argue that Lyman-break galaxies must be very biased tracers of mass, with an effective bias on mass scale M~10^{15}M_{\sun} ranging from b~2 for \Omega_M=0.2 to b >~6 for \Omega_M=1. In a Cold Dark Matter scenario the large bias values suggest that individual Lyman-break galaxies are associated with dark halos of mass M~10^{12} M_{\sun}, reinforcing the interpretation of these objects as the progenitors of massive galaxies at the present epoch. Preliminary results of spectroscopy in additional fields suggest that such large structures are common at z~3, with about one similar structure per survey field. The implied space density is consistent with the possibility that we are observing moderately rich clusters of galaxies in their early non-linear evolution. Finally, the spectrum of one of the QSOs discovered in our survey (z_{em} = 3.356) exhibits metal line absorption systems within the 3 redshift bins having the largest number of galaxies in field, z = 2.93, 3.09, and 3.28. These results are the first from an ongoing ``targeted'' redshift survey designed to explore the nature and distribution of star-forming galaxies in the redshift range 2.7 <~ z <~ 3.4.Comment: 24 pages including 5 ps figures, LaTeX, uses aaspp4.sty, to appear in the Astrophysical Journal. Also available at ftp://astro.caltech.edu/users/ccs/spike_preprint.ps.g

X-shooter Observations of the Gravitational Lens System CASSOWARY 5

We confirm an eighth gravitational lens system in the CASSOWARY catalogue. Exploratory observations with the X-shooter spectrograph on the VLT show the system CSWA5 to consist of at least three images of a blue star-forming galaxy at z = 1.0686, lensed by an apparent foreground group of red galaxies one of which is at z = 0.3877. The lensed galaxy exhibits a rich spectrum with broad interstellar absorption lines and a wealth of nebular emission lines. Preliminary analysis of these features shows the galaxy to be young, with an age of 25-50 Myr. With a star-formation rate of approximately 20 solar masses/yr, the galaxy has already assembled a stellar mass of 3 x 10^9 solar masses and reached half-solar metallicity. Its blue spectral energy distribution and Balmer line ratios suggest negligible internal dust extinction. A more in-depth analysis of the properties of this system is currently hampered by the lack of a viable lensing model. However, it is already clear that CSWA5 shares many of its physical characteristics with the general population of UV-selected galaxies at redshifts z = 1-3, motivating further study of both the source and the foreground mass concentration responsible for the gravitational lensing.Comment: 12 pages; Accepted for publication in MNRA

Dust Devil Sediment Transport: From Lab to Field to Global Impact

The impact of dust aerosols on the climate and environment of Earth and Mars is complex and forms a major area of research. A difficulty arises in estimating the contribution of small-scale dust devils to the total dust aerosol. This difficulty is due to uncertainties in the amount of dust lifted by individual dust devils, the frequency of dust devil occurrence, and the lack of statistical generality of individual experiments and observations. In this paper, we review results of observational, laboratory, and modeling studies and provide an overview of dust devil dust transport on various spatio-temporal scales as obtained with the different research approaches. Methods used for the investigation of dust devils on Earth and Mars vary. For example, while the use of imagery for the investigation of dust devil occurrence frequency is common practice for Mars, this is less so the case for Earth. Modeling approaches for Earth and Mars are similar in that they are based on the same underlying theory, but they are applied in different ways. Insights into the benefits and limitations of each approach suggest potential future research focuses, which can further reduce the uncertainty associated with dust devil dust entrainment. The potential impacts of dust devils on the climates of Earth and Mars are discussed on the basis of the presented research results

Genetic Testing to Inform Epilepsy Treatment Management From an International Study of Clinical Practice

IMPORTANCE: It is currently unknown how often and in which ways a genetic diagnosis given to a patient with epilepsy is associated with clinical management and outcomes. OBJECTIVE: To evaluate how genetic diagnoses in patients with epilepsy are associated with clinical management and outcomes. DESIGN, SETTING, AND PARTICIPANTS: This was a retrospective cross-sectional study of patients referred for multigene panel testing between March 18, 2016, and August 3, 2020, with outcomes reported between May and November 2020. The study setting included a commercial genetic testing laboratory and multicenter clinical practices. Patients with epilepsy, regardless of sociodemographic features, who received a pathogenic/likely pathogenic (P/LP) variant were included in the study. Case report forms were completed by all health care professionals. EXPOSURES: Genetic test results. MAIN OUTCOMES AND MEASURES: Clinical management changes after a genetic diagnosis (ie, 1 P/LP variant in autosomal dominant and X-linked diseases; 2 P/LP variants in autosomal recessive diseases) and subsequent patient outcomes as reported by health care professionals on case report forms. RESULTS: Among 418 patients, median (IQR) age at the time of testing was 4 (1-10) years, with an age range of 0 to 52 years, and 53.8% (n = 225) were female individuals. The mean (SD) time from a genetic test order to case report form completion was 595 (368) days (range, 27-1673 days). A genetic diagnosis was associated with changes in clinical management for 208 patients (49.8%) and usually (81.7% of the time) within 3 months of receiving the result. The most common clinical management changes were the addition of a new medication (78 [21.7%]), the initiation of medication (51 [14.2%]), the referral of a patient to a specialist (48 [13.4%]), vigilance for subclinical or extraneurological disease features (46 [12.8%]), and the cessation of a medication (42 [11.7%]). Among 167 patients with follow-up clinical information available (mean [SD] time, 584 [365] days), 125 (74.9%) reported positive outcomes, 108 (64.7%) reported reduction or elimination of seizures, 37 (22.2%) had decreases in the severity of other clinical signs, and 11 (6.6%) had reduced medication adverse effects. A few patients reported worsening of outcomes, including a decline in their condition (20 [12.0%]), increased seizure frequency (6 [3.6%]), and adverse medication effects (3 [1.8%]). No clinical management changes were reported for 178 patients (42.6%). CONCLUSIONS AND RELEVANCE: Results of this cross-sectional study suggest that genetic testing of individuals with epilepsy may be materially associated with clinical decision-making and improved patient outcomes

Evidence for Excitonic Superfluidity in a Bilayer Two-Dimensional Electron System

The discovery of the integer quantum Hall effect (QHE) and the fractional quantum Hall effect (FQHE) revealed that unexpected physics could be found in a seemingly very simple system: free electrons constrained to move in only two dimensions. Adding a degree of complexity to this system by bringing two of these layers of two-dimensional electrons into close proximity, multiplies the exciting physical phenomena available for study and discovery. This thesis is a report on electrical transport studies of bilayer two-dimensional electron systems (2DES) found in GaAs/AlGaAs double quantum well semiconductor heterostructures. Through studies at zero magnetic field using a fairly new transport measurement called "Coulomb drag" pure electron-electron scattering is measured with unprecedented accuracy and clarity. In large magnetic fields applied perpendicular to the electron layers, at the right combination of magnetic field strength, electron density and layer separation, a new, uniquely bilayer, many-body quantum ground state exists that can be described alternately as an itinerant pseudospin ferromagnet or as a Bose-Einstein condensate (BEC) of interlayer excitons. This bilayer quantum state was first predicted theoretically fifteen years ago, and its discovery and exploration is the basis of this thesis. In this thesis, transport measurements allow for the direct detection of the BEC of excitons by their ability to flow with vanishing resistance and vanishing influence from the large external magnetic field. Excitonic BEC has been pursued experimentally for almost 40 years, but this thesis likely represents the first detection of the elusive state. Coulomb drag is found to be an excellent probe of the phase transition out of the bilayer quantum state and is used to extend the mapping of the phase diagram into the temperature and layer density imbalance planes

Kansas legislators prioritize obesity, but overlook nutrition and physical activity issues

State-level policymakers play an important role in the fight against obesity due to their ability to create policies that influence opportunities for physical activity and nutrition. Objective: In 2011, we investigated how Kansas policymakers regarded obesity, nutrition and physical activity in comparison to other issues. Design: This study used a cross-sectional design. Setting: This study was conducted in Kansas, a predominately rural and Republican Midwestern state. Participants: All 181 state-level policymakers in Kansas were mailed a cover letter and survey. Main Outcome Measures: Policymakers were asked to identify and rate the importance of issues or problems in need of attention for Kansas. The 2011 state legislative report was content analyzed and coded to match the survey. Comparisons were made by political party. Results: Of the 49 policymakers who completed a survey, 37 were Republicans and 43 were elected to their position. Although obesity was rated second highest behind jobs, physical activity and nutrition-related issues were not seen as important problems; as well, little corresponding legislation was introduced. Other key issues identified by policymakers included budget/spending/taxes, education, jobs/economy, and drug abuse, with more legislation reflecting these problems. Democrats ranked 11 issues as more significant problems than did Republicans: quality of public education, poverty, access to healthcare, lack of affordable housing, ethics in government, lack of public health training, access to healthy groceries, lack of pedestrian walkways/crosswalks/sidewalks, pedestrian safety, air pollution, and global warming (P < .05). Conclusions: There is a need to provide more public health education on the relationship between nutrition and physical activity issues and obesity for Kansas policymakers. Issues identified may be similar for other predominately rural and Republican states

Coherent States in Double Quantum Well Systems

Copyright (C) 2011 Yogesh Joglekar et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.Physic