Ground-penetrating radar observations of enhanced biological activity in a sandbox reactor

In this study, we evaluate the use of ground-penetrating radar (GPR) to investigate the effects of bacterial activity in water saturated sand. A 90-day laboratory-scale controlled experiment was conducted in a flow-through polycarbonate sandbox using groundwater from the Kansas River alluvial aquifer as inoculum. After 40 days of collecting baseline data, bacterial growth was stimulated in the sandbox by the addition of a carbon and nutrient solution on a weekly basis. Radar signal travel time and attenuation were shown to increase downgradient of the nutrient release wells relative to upgradient locations. After 60 days, the frequency of nutrient injections was increased to twice per week, after which gaseous bubbles were visually observed downgradient of the nutrient release wells. Visual observation of active gas production correlated spatially and temporally with a rapid decrease in radar signal travel time, confirming that GPR can monitor the generation of biogenic gases in this system. Analysis of the sediments indicated microbial lipid biomass increased by approximately one order of magnitude and there were no changes in the inorganic carbon content of bulk sediment mineralogy. These findings suggest that the increase in biomass and gas production may be responsible for the observed changes in radar signal travel time reported in this study. Therefore, this study provides evidence that GPR can be used to monitor biological activity in water saturated sand.Funding for this project was through the National Science Foundation CAREER grant 0134545 awarded to J.F. Devlin and NSF EAR/IF-0345445 for acquisition of GPR instrumentation awarded to G. Tsoflias. The opinions, findings, and recommendations of this study are the views the author(s) and do not necessarily reflect the views and opinions of the National Science Foundation. We would like to thank Mike McGlashan, Kwan Yee Cheng, Kelly Peterson, Lindsay Mayer, and Breanna Huff for assistance with this project. We also thank two anonymous reviewers for their helpful comments that led to the improvement of this manuscript

The time resolution of the St. Petersburg paradox

A resolution of the St. Petersburg paradox is presented. In contrast to the standard resolution, utility is not required. Instead, the time-average performance of the lottery is computed. The final result can be phrased mathematically identically to Daniel Bernoulli's resolution, which uses logarithmic utility, but is derived using a conceptually different argument. The advantage of the time resolution is the elimination of arbitrary utility functions.Comment: 20 pages, 1 figur

HI Narrow Self-Absorption in Dark Clouds: Correlations with Molecular Gas and Implications for Cloud Evolution and Star Formation

We present the results of a comparative study of HI narrow self-absorption (HINSA), OH, 13CO, and C18O in five dark clouds. The HINSA follows the distribution of the emission of the carbon monoxide isotopologues, and has a characteristic size close to that of 13CO. This confirms that the HINSA is produced by cold HI which is well mixed with molecular gas in well-shielded regions. The ratio of the atomic hydrogen density to total proton density for these sources is 5 to 27 x 10^{-4}. Using cloud temperatures and the density of HI, we set an upper limit to the cosmic ray ionization rate of 10^{-16} s^{-1}. Comparison of observed and modeled fractional HI abundances indicates ages for these clouds to be 10^{6.5} to 10^{7} yr. The low values of the HI density we have determined make it certain that the time scale for evolution from an atomic to an almost entirely molecular phase, must be a minimum of several million years. This clearly sets a lower limit to the overall time scale for star formation and the lifetime of molecular clouds

Measurements of Anisotropy in the Cosmic Microwave Background Radiation at 0.5 Degree Angular Scales Near the Star Gamma Ursae Minoris

We present results from a four frequency observation of a 6 x 0.6 degree strip of the sky centered near the star Gamma Ursae Minoris during the fourth flight of the Millimeter-wave Anisotropy eXperiment (MAX). The observation was made with a 1.4 degree peak-to-peak sinusoidal chop in all bands. The FWHM beam sizes were 0.55 +/- 0.05 degrees at 3.5 cm-1 and 0.75 +/-0.05 degrees at 6, 9, and 14 cm-1. During this observation significant correlated structure was observed at 3.5, 6 and 9 cm-1 with amplitudes similar to those observed in the GUM region during the second and third flights of MAX. The frequency spectrum is consistent with CMB and inconsistent with thermal emission from interstellar dust. The extrapolated amplitudes of synchrotron and free-free emission are too small to account for the amplitude of the observed structure. If all of the structure is attributed to CMB anisotropy with a Gaussian autocorrelation function and a coherence angle of 25', then the most probable values of DeltaT/TCMB in the 3.5, 6, and 9 cm-1 bands are 4.3 (+2.7, -1.6) x 10-5, 2.8 (+4.3, -1.1) x 10-5, and 3.5 (+3.0, -1.6) x 10-5 (95% confidence upper and lower limits), respectively.Comment: 16 pages, postscrip

Measurements of Anisotropy in the Cosmic Microwave Background Radiation at Degree Angular Scales Near the Stars Sigma Hercules and Iota Draconis

We present results from two four-frequency observations centered near the stars Sigma Hercules and Iota Draconis during the fourth flight of the Millimeter-wave Anisotropy eXperiment (MAX). The observations were made of 6 x 0.6-degree strips of the sky with 1.4-degree peak to peak sinusoidal chop in all bands. The FWHM beam sizes were 0.55+/-0.05 degrees at 3.5 cm-1 and a 0.75+/-0.05 degrees at 6, 9, and 14 cm-1. Significant correlated structures were observed at 3.5, 6 and 9 cm-1. The spectra of these signals are inconsistent with thermal emission from known interstellar dust populations. The extrapolated amplitudes of synchrotron and free-free emission are too small to account for the amplitude of the observed structures. If the observed structures are attributed to CMB anisotropy with a Gaussian autocorrelation function and a coherence angle of 25', then the most probable values are DT/TCMB = (3.1 +1.7-1.3) x 10^-5 for the Sigma Hercules scan, and DT/TCMB = (3.3 +/- 1.1) x 10^-5 for the Iota Draconis scan (95% confidence upper and lower limits). Finally a comparison of all six MAX scans is presented.Comment: 13 pages, postscript file, 2 figure

Cosmic Microwave Background Anisotropy Window Functions Revisited

The primary results of most observations of cosmic microwave background (CMB) anisotropy are estimates of the angular power spectrum averaged through some broad band, called band-powers. These estimates are in turn what are used to produce constraints on cosmological parameters due to all CMB observations. Essential to this estimation of cosmological parameters is the calculation of the expected band-power for a given experiment, given a theoretical power spectrum. Here we derive the "band power" window function which should be used for this calculation, and point out that it is not equivalent to the window function used to calculate the variance. This important distinction has been absent from much of the literature: the variance window function is often used as the band-power window function. We discuss the validity of this assumed equivalence, the role of window functions for experiments that constrain the power in {\it multiple} bands, and summarize a prescription for reporting experimental results. The analysis methods detailed here are applied in a companion paper to three years of data from the Medium Scale Anisotropy Measurement.Comment: 5 pages, 1 included .eps figure, PRD in press---final published versio

Effects of CO2 on H2O band profiles and band strengths in mixed H2O:CO2 ices

H2O is the most abundant component of astrophysical ices. In most lines of sight it is not possible to fit both the H2O 3 um stretching, the 6 um bending and the 13 um libration band intensities with a single pure H2O spectrum. Recent Spitzer observations have revealed CO2 ice in high abundances and it has been suggested that CO2 mixed into H2O ice can affect relative strengths of the 3 um and 6 um bands. We used laboratory infrared transmission spectroscopy of H2O:CO2 ice mixtures to investigate the effects of CO2 on H2O ice spectral features at 15-135 K. We find that the H2O peak profiles and band strengths are significantly different in H2O:CO2 ice mixtures compared to pure H2O ice. In all H2O:CO2 mixtures, a strong free-OH stretching band appears around 2.73 um, which can be used to put an upper limit on the CO2 concentration in the H2O ice. The H2O bending mode profile also changes drastically with CO2 concentration; the broad pure H2O band gives way to two narrow bands as the CO2 concentration is increased. This makes it crucial to constrain the environment of H2O ice to enable correct assignments of other species contributing to the interstellar 6 um absorption band. The amount of CO2 present in the H2O ice of B5:IRS1 is estimated by simultaneously comparing the H2O stretching and bending regions and the CO2 bending mode to laboratory spectra of H2O, CO2, H2O:CO2 and HCOOH.Comment: 12 pages, 11 figures, accepted by A&

Evaluation of changes in sleep breathing patterns after primary palatoplasty in cleft children

Introduction: There is a need to more clearly understand the characteristics of breathing patterns in children with cleft palate in the first year of life, as there is little data available to guide current practice. Pierre Robin patients are known to have a higher incidence, however we hypothesised sleep breathing disturbance is not confined to this sub-group of cleft patient. Methods: We conducted a prospective observational study of sleep disordered breathing patterns in a cohort of infants with oro-nasal clefts (cleft palate with or without cleft lip) to describe the spectrum of sleep breathing patterns both pre and post palate repair. Sleep breathing studies were performed pre- and post-operatively in sequential infants referred to a regional cleft lip and palate unit. Results of sleep breathing studies were analysed according to American Academy of Sleep Medicine scoring guidelines and correlated with clinical history and details of peri-operative respiratory compromise. The degree of sleep disordered breathing was characterised using desaturation indices (number of desaturations from baseline SpO2 of >=4%, per hour). Results: Thirty-nine infants were included in this study, twenty-five female and fourteen male. Twelve had isolated Cleft Palate as part of an associated syndrome. Patients were categorised into Isolated Cleft Palate, Isolated Cleft Palate in the context of Pierre Robin Sequence, and those with Cleft Lip and Palate. All groups demonstrated some degree of sleep breathing abnormality. Not unsurprisingly the eight infants with Pierre Robin Sequence had a significantly higher desaturation index before surgical intervention (p=0.043), and were more likely to require a pre-operative airway intervention (p=0.009). Palate repair in this group did not alter the relative distribution of patients in each severity category of sleep disorder breathing. Surgical repair of the secondary palate in the remaining children was associated with some improvement but by no means complete resolution of their sleep disordered breathing patterns. Conclusions: We conclude that sleep breathing disturbance is not confined to Pierre Robin patients alone and all cleft palate patients should undergo pre-operative and post-operative sleep breathing analysis

The Atacama Cosmology Telescope: Physical Properties of Sunyaev-Zel'dovich Effect Clusters on the Celestial Equator

We present the optical and X-ray properties of 68 galaxy clusters selected via the Sunyaev-Zel'dovich Effect at 148 GHz by the Atacama Cosmology Telescope (ACT). Our sample, from an area of 504 square degrees centered on the celestial equator, is divided into two regions. The main region uses 270 square degrees of the ACT survey that overlaps with the co-added ugriz imaging from the Sloan Digital Sky Survey (SDSS) over Stripe 82 plus additional near-infrared pointed observations with the Apache Point Observatory 3.5-meter telescope. We confirm a total of 49 clusters to z~1.3, of which 22 (all at z>0.55) are new discoveries. For the second region the regular-depth SDSS imaging allows us to confirm 19 more clusters up to z~0.7, of which 10 systems are new. We present the optical richness, photometric redshifts, and separation between the SZ position and the brightest cluster galaxy (BCG). We find no significant offset between the cluster SZ centroid and BCG location and a weak correlation between optical richness and SZ-derived mass. We also present X-ray fluxes and luminosities from the ROSAT All Sky Survey which confirm that this is a massive sample. One of the newly discovered clusters, ACT-CL J0044.4+0113 at z=1.1 (photometric), has an integrated XMM-Newton X-ray temperature of kT_x=7.9+/-1.0 keV and combined mass of M_200a=8.2(-2.5,+3.3)x10^14 M_sun/h70 placing it among the most massive and X-ray-hot clusters known at redshifts beyond z=1. We also highlight the optically-rich cluster ACT-CL J2327.4-0204 (RCS2 2327) at z=0.705 (spectroscopic) as the most significant detection of the whole equatorial sample with a Chandra-derived mass of M_200a=1.9(-0.4,+0.6)x10^15 M_sun/h70, comparable to some of the most massive known clusters like "El Gordo" and the Bullet Cluster.Comment: 18 pages, 12 figures. Accepted to the Astrophysical Journal. New version includes minor changes in the accepted pape

Measuring star formation in high-z massive galaxies: A mid-infrared to submillimeter study of the GOODS NICMOS Survey sample

We present measurements of the mean mid-infrared-to-submillimeter flux densities of massive (M\ast \approx 2 \times 10^11 Msun) galaxies at redshifts 1.7 < z < 2.9, obtained by stacking positions of known objects taken from the GOODS NICMOS Survey (GNS) catalog on maps: at 24 {\mu}m (Spitzer/MIPS); 70, 100, and 160{\mu}m (Herschel/PACS); 250, 350, 500{\mu}m (BLAST); and 870{\mu}m (LABOCA). A modified blackbody spectrum fit to the stacked flux densities indicates a median [interquartile] star-formation rate of SFR = 63 [48, 81] Msun yr^-1 . We note that not properly accounting for correlations between bands when fitting stacked data can significantly bias the result. The galaxies are divided into two groups, disk-like and spheroid-like, according to their Sersic indices, n. We find evidence that most of the star formation is occurring in n \leq 2 (disk-like) galaxies, with median [interquartile] SFR = 122 [100,150] Msun yr^-1, while there are indications that the n > 2 (spheroid-like) population may be forming stars at a median [interquartile] SFR = 14 [9,20] Msun yr^-1, if at all. Finally, we show that star formation is a plausible mechanism for size evolution in this population as a whole, but find only marginal evidence that it is what drives the expansion of the spheroid-like galaxies.Comment: Accepted by MNRAS. 10 pages, 3 figures, 3 table