Highly Ionized High-Velocity Clouds toward PKS 2155-304 and Markarian 509

To gain insight into four highly ionized high-velocity clouds (HVCs) discovered by Sembach et al. (1999), we have analyzed data from the Hubble Space Telescope (HST) and Far Ultraviolet Spectroscopic Explorer (FUSE) for the PKS 2155-304 and Mrk 509 sight lines. We measure strong absorption in OVI and column densities of multiple ionization stages of silicon (SiII/III/IV) and carbon (CII/III/IV). We interpret this ionization pattern as a multiphase medium that contains both collisionally ionized and photoionized gas. Toward PKS 2155-304, for HVCs at -140 and -270 km/s, respectively, we measure logN(OVI)=13.80+/-0.03 and log N(OVI)=13.56+/-0.06; from Lyman series absorption, we find log N(HI)=16.37^(+0.22)_(-0.14) and 15.23^(+0.38)_(-0.22). The presence of high-velocity OVI spread over a broad (100 km/s) profile, together with large amounts of low-ionization species, is difficult to reconcile with the low densities, n=5x10^(-6) cm^(-3), in the collisional/photoionization models of Nicastro et al. (2002), although the HVCs show a similar relation in N(SiIV)/N(CIV) versus N(CII)/N(CIV) as high-z intergalactic clouds. Our results suggest that the high-velocity OVI in these absorbers do not necessarily trace the WHIM, but instead may trace HVCs with low total hydrogen column density. We propose that the broad high-velocity OVI absorption arises from shock ionization, at bowshock interfaces produced from infalling clumps of gas with velocity shear. The similar ratios of high ions for HVC Complex C and these highly ionized HVCs suggest a common production mechanism in the Galactic halo.Comment: 38 pages, including 10 figures. ApJ, 10 April, 2004. Replaced with accepted versio

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Comment on Work as an Inclusive Part of Population Health Inequities Research and Prevention. [Am J Public Health. 2018] New Horizons for Occupational Health Surveillance. [Am J Public Health. 2018

Unitary k-designs from random number-conserving quantum circuits

Local random circuits scramble efficiently and accordingly have a range of applications in quantum information and quantum dynamics. With a global $U(1)$ charge however, the scrambling ability is reduced; for example, such random circuits do not generate the entire group of number-conserving unitaries. We establish two results using the statistical mechanics of $k$-fold replicated circuits. First, we show that finite moments cannot distinguish the ensemble that local random circuits generate from the Haar ensemble on the entire group of number conserving unitaries. Specifically, the circuits form a $k_c$-design with $k_c = O(L^d)$ for a system in $d$ spatial dimensions with linear dimension $L$. Second, for $k < k_c$, the depth $\tau$ to converge to a $k$-design scales as $\tau \gtrsim k L^{d+2}$. In contrast, without number conservation $\tau \gtrsim k L^{d}$. The convergence of the circuit ensemble is controlled by the low-energy properties of a frustration-free quantum statistical model which spontaneously breaks $k$ $U(1)$ symmetries. The associated Goldstone modes are gapless and lead to the predicted scaling of $\tau$. Our variational bounds hold for arbitrary spatial and qudit dimensions; we conjecture they are tight.Comment: 18 pages, 2 figure

Graphene Oxidation: Thickness Dependent Etching and Strong Chemical Doping

Patterned graphene shows substantial potential for applications in future molecular-scale integrated electronics. Environmental effects are a critical issue in a single layer material where every atom is on the surface. Especially intriguing is the variety of rich chemical interactions shown by molecular oxygen with aromatic molecules. We find that O2 etching kinetics vary strongly with the number of graphene layers in the sample. Three-layer-thick samples show etching similar to bulk natural graphite. Single-layer graphene reacts faster and shows random etch pits in contrast to natural graphite where nucleation occurs at point defects. In addition, basal plane oxygen species strongly hole dope graphene, with a Fermi level shift of ~0.5 eV. These oxygen species partially desorb in an Ar gas flow, or under irradiation by far UV light, and readsorb again in an O2 atmosphere at room temperature. This strongly doped graphene is very different than graphene oxide made by mineral acid attack.Comment: 15 pages, 5 figure

Coastal Science for Resilience and Management at the Cape Hatteras National Seashore, NC, USA

National seashores are cherished public lands with rich environmental, cultural, and historic resources. The Cape Hatteras National Seashore is one such coastal asset that is both bountiful yet vulnerable, with historic lighthouses, critical habitats, and recreational amenities alike facing threats of sea-level rise and continual storm and climate change impacts. Over 3 million visitors to the Seashore in 2021 set an annual visitation record. Historic resources such as the Bodie Island Lighthouse and Ocracoke Lighthouse are among the most visited sites, yet these assets are also among those most vulnerable to flooding, compromised structural integrity, and reduced accessibility. Future challenges to the protection and management of such resources are already being felt in the form of storms, extreme rainfall, and recurrent compound flooding. Such threats are also coincident with increasing visitation and recreational demand. This paper examines the science-based data that are being collected and management efforts underway to inform future planning, intervention, or adaptation to sea-level rise and barrier island evolution. The paper identifies the opportunities for mitigation and adaptation as well as potential environmental tipping points and limits to resilience by assessing the frequency and magnitude of flooding events and shoreline change

Anatomy of Cirrus Clouds: Results from the Emerald Airborne Campaigns

2000 FLORIDA AVE NW, WASHINGTON, USA, DC, 2000

A systematic review of quality of life of adults on the autism spectrum

Autism spectrum disorder is associated with co-existing conditions that may adversely affect an individual’s quality of life. No systematic review of quality of life of adults on the autism spectrum has been conducted. Our objectives were as follows: (1) review the evidence about quality of life for adults on the autism spectrum; (2) critically appraise current practice in assessing quality of life of adults on the autism spectrum. We searched bibliographic databases and other literature to identify studies using a direct measure of quality of life of adults on the autism spectrum. Hand searching of reference lists, citation searching and personal communication with field experts were also undertaken. In total, 827 studies were identified; 14 were included. Only one quality of life measure designed for use with the general autism spectrum population was identified. Quality of life of adults on the autism spectrum is lower than that of typically developing adults, when measured with tools designed for the general population. There are no comprehensive autism spectrum disorder–specific quality of life measurement tools validated for use with representative samples of adults on the autism spectrum. There is a pressing need to develop robust measures of quality of life of autistic adults

Carbon-based Materials for Extracting Urea to Recycle Waste Water in Space Applications

Recovering water aboard spacecrafts is essential for space exploration. Bringing fresh water to outer space for crew members is an expensive process. Therefore, recycling waste water to usable water is necessary for long term space missions and applications. Previous experiments showed that urea, which is the main substance in urine, prematurely fouled the membrane used in the water treatment process. In this experiment we investigated different carbon-based materials to act as a urea pre-treatment step. A total of nine different materials were tested for the amount of urea they can adsorb. The adsorption rate will enable us to decide which material is best for the pre-treatment process. Out of nine adsorbents, three had good adsorption rate with over 90% of urea is adsorbed

Improved transformation efficiency of group A Streptococcus by inactivation of a type I restriction modification system

Streptococcus pyogenes or group A Streptococcus (GAS) is a leading cause of bacterial pharyngitis, skin and soft tissue infections, life-threatening invasive infections, and the post-infectious autoimmune syndromes of acute rheumatic fever and post-streptococcal glomerulonephritis. Genetic manipulation of this important pathogen is complicated by resistance of the organism to genetic transformation. Very low transformation efficiency is attributed to recognition and degradation of introduced foreign DNA by a type I restriction-modification system encoded by the hsdRSM locus. DNA sequence analysis of this locus in ten GAS strains that had been previously transformed with an unrelated plasmid revealed that six of the ten harbored a spontaneous mutation in hsdR, S, or M. The mutations were all different, and at least five of the six were predicted to result in loss of function of the respective hsd gene product. The unexpected occurrence of such mutations in previously transformed isolates suggested that the process of transformation selects for spontaneous inactivating mutations in the Hsd system. We investigated the possibility of exploiting the increased transformability of hsd mutants by constructing a deletion mutation in hsdM in GAS strain 854, a clinical isolate representative of the globally dominant M1T1 clonal group. Mutant strain 854ΔhsdM exhibited a 5-fold increase in electrotransformation efficiency compared to the wild type parent strain and no obvious change in growth or off-target gene expression. We conclude that genetic transformation of GAS selects for spontaneous mutants in the hsdRSM restriction modification system. We propose that use of a defined hsdM mutant as a parent strain for genetic manipulation of GAS will enhance transformation efficiency and reduce the likelihood of selecting spontaneous hsd mutants with uncharacterized genotypes