Remote Sensing Analysis of Selected Terrestrial Impact Craters and a Suspected Impact Structure in South Korea using Space Shuttle Photographs

Typical morphological elements for impact craters were detected on all analyzed Shuttle photographs. Features with diameters smaller than 2 km could not be successfully analyzed. The search for suitable Shuttle scenes was successfully performed using on-line Internet databases. Image enhancement and lineament analysis were also performed on the acquired Shuttle, Landsat and SPOT images of a suspected impact feature in South Korea. A fault bounded polygonal rim and a central uplift were identified on all images. A distinct system of annular and radial faults was not detected. The results of the study do not exclude the possibility of a meteoritic origin of this structure

APOCALYPSE NO: Population Aging and the Future of Health Care Systems

Illness increases with age. All else equal, an older population has greater needs for health care. This logic has led to dire predictions of skyrocketing costs-- "apocalyptic demography". Yet numerous studies have shown that aging effects are relatively small, and all else is not equal. Cost projections rest on specific assumptions about trends in age- specific morbidity and health care use that are far from self-evident. Sharply contrasting assumptions, for example, are made by Fries, who foresees a "compression of morbidity" and falling needs. Long term trends in health care use in British Columbia show minimal effects of population aging, but major effects, up and down, from changes in age- specific use patterns. Why then is the demographic apocalypse story so persistent, despite numerous contrary studies? It serves identifiable economic interests.aging, health care utilization, demography, health care financing

Characterization of Soil Shrink-Swell Potential Using the Texas VNIR Diffuse Reflectance Spectroscopy Library

Shrinking and swelling soils cause extensive infrastructure and economic damage worldwide. Shrink-swell soils are of great concern in Texas for two reasons, 1) Texas has the most acreage of shrink-swell soils in the United States, and 2) yearly evapotranspiration rates exceed those of precipitation creating optimal conditions for soil wetting and drying cycles. This study was conducted to determine if visible near infrared diffuse reflectance spectroscopy (VNIR-DRS) can be used to predict the coefficient of linear extensibility (COLE) of soils. If successful, VNIR-DRS would provide a means to rapidly and inexpensively quantify a soil’s shrink-swell potential real-time. Using soils that have been previously analyzed and archived in the Texas Agrilife Research Soil Characterization Laboratory, our objectives were to: 1) predict the coefficient of linear extractability (COLE) using spectroscopy, 2) predict COLE using measurements of total clay and cation exchange capacity (CEC), and 3) compare the two models. A total of 2454 soil samples were scanned to create the Texas spectral library. Of these samples, 1296 had COLE measurements. Seventy percent of the COLE samples were randomly selected to build a calibration model using partial least squares regression. The remaining thirty percent were used to validate the calibration model. The coefficient of determination (R2), root mean square deviation (RMSD), and relative percent difference (RPD) were calculated to assess the prediction models. The COLE prediction using spectroscopy had an R2, RMSD, and RPD of 0.61, 0.028, and 1.6, respectively. Using stepwise regression and backward elimination, we determined that CEC and total clay together were the best predictors of COLE with R2, RMSD, and RPD of 0.82, 0.019, and 2.3, respectively. According to the RPD, using spectroscopy to predict COLE has some predictive value, while using CEC and total clay is more effective and stable. However, spectroscopy data collection is more rapid and has fixed costs

Channeling in direct dark matter detection I: channeling fraction in NaI (Tl) crystals

The channeling of the ion recoiling after a collision with a WIMP changes the ionization signal in direct detection experiments, producing a larger signal than otherwise expected. We give estimates of the fraction of channeled recoiling ions in NaI (Tl) crystals using analytic models produced since the 1960's and 70's to describe channeling and blocking effects. We find that the channeling fraction of recoiling lattice nuclei is smaller than that of ions that are injected into the crystal and that it is strongly temperature dependent.Comment: 37 pages, 35 figures, Accepted for publication in JCAP on 27 October 2010, Minor revisions: added an appendix, updated references, updated Fig. 9, corrected a few typo

Narrow Line X-Ray Calibration Source for High Resolution Microcalorimeters

We are developing a narrow line calibration source for use with X-ray microcalorimeters. At energies below 300 electronvolts fluorescent lines are intrinsically broad, making calibration of high resolution detectors difficult. This source consists of a 405 nanometers (3 electronvolts) laser diode coupled to an optical fiber. The diode is pulsed to create approximately one hundred photons in a few microseconds. If the pulses are short compared to the rise time of the detector, they will be detected as single events with a total energy in the soft X-ray range. Poisson fluctuations in photon number per pulse create a comb of X-ray lines with 3 electronvolts spacing, so detectors with energy resolution better than 2 electronvolts are required to resolve the individual lines. Our currently unstabilized diode has a multimode width less than 1 nanometer, giving a 300 electronvolt event a Full width at half maximum (FWHM) less than 0.1 electronvolts. By varying the driving voltage, or pulse width, the source can produce a comb centered on a wide range of energies. The calibration events are produced at precisely known times. This allows continuous calibration of a flight mission without contaminating the observed spectrum and with minimal deadtime

A model for the evolution of prokaryotic DNA restriction-modification systems based upon the structural malleability of Type I restriction-modification enzymes

Restriction Modification (RM) systems prevent the invasion of foreign genetic material into bacterial cells by restriction and protect the host's genetic material by methylation. They are therefore important in maintaining the integrity of the host genome. RM systems are currently classified into four types (I to IV) on the basis of differences in composition, target recognition, cofactors and the manner in which they cleave DNA. Comparing the structures of the different types, similarities can be observed suggesting an evolutionary link between these different types. This work describes the ‘deconstruction’ of a large Type I RM enzyme into forms structurally similar to smaller Type II RM enzymes in an effort to elucidate the pathway taken by Nature to form these different RM enzymes. Based upon the ability to engineer new enzymes from the Type I ‘scaffold’, an evolutionary pathway and the evolutionary pressures required to move along the pathway from Type I RM systems to Type II RM systems are proposed. Experiments to test the evolutionary model are discussed

Exotic smooth structures on 4-manifolds with zero signature

For every integer $k\geq 2$, we construct infinite families of mutually nondiffeomorphic irreducible smooth structures on the topological $4$-manifolds $(2k-1)(S^2\times S^2)$ and (2k-1)(\CP#\CPb), the connected sums of $2k-1$ copies of $S^2\times S^2$ and \CP#\CPb.Comment: 6 page

Constructions of generalized complex structures in dimension four

Four-manifold theory is employed to study the existence of (twisted) generalized complex structures. It is shown that there exist (twisted) generalized complex structures that have more than one type change loci. In an example-driven fashion, (twisted) generalized complex structures are constructed on a myriad of four-manifolds, both simply and non-simply connected, which are neither complex nor symplectic

A coupled channel analysis of the centrally produced K+K- and pi+pi- final states in pp interactions at 450 GeV/c

A coupled channel analysis of the centrally produced K+K- and pi+pi- final states has been performed in pp collisions at an incident beam momentum of 450 GeV/c. The pole positions and branching ratios to pipi and KK of the f0(980), f0(1370), f0(1500) and f0(1710) have been determined. A systematic study of the production properties of all the resonances observed in the pi+pi- and K+K- channels has been performed.Comment: 16 pages, Latex, 5 Figure

Cigarette pack messages about toxic chemicals: A randomised clinical trial

Background The USA can require tobacco companies to disclose information about harmful and potentially harmful chemicals in cigarette smoke, but the impact of these messages is uncertain. We sought to assess the effect of placing messages about toxic chemicals on smokers' cigarette packs. Methods Participants were 719 adult cigarette smokers from California, USA, recruited from September 2016 through March 2017. We randomly assigned smokers to receive either factual messages about chemicals in cigarette smoke and their health harms (intervention) or messages about not littering cigarette butts (control) on the side of their cigarette packs for 3 weeks. The primary trial outcome was intention to quit smoking. Results In intent-to-treat analyses, smokers whose packs had chemical messages did not have higher intentions to quit smoking at the end of the trial than those whose packs had control messages (P=0.56). Compared with control messages, chemical messages led to higher awareness of the chemicals (28% vs 15%, P<0.001) and health harms (60% vs 52%, P=0.02) featured in the messages. In addition, chemical messages led to greater negative affect, thinking about the chemicals in cigarettes and the harms of smoking, conversations about the messages and forgoing a cigarette (all P<0.05). Discussion Chemical messages on cigarette packs did not lead to higher intentions to quit among smokers in our trial. However, chemical messages informed smokers of chemicals in cigarettes and harms of smoking, which directly supports their implementation and would be critical to defending the messages against cigarette company legal challenges. Trial registration number NCT02785484