Search

We translocated 120 Agassiz's desert tortoises to 5 sites in Nevada and Utah to evaluate the effects of translocation on tortoise survivorship, reproduction, and habitat use. Translocation sites included several elevations, and extended to sites with vegetation assemblages not typically associated with desert tortoises in order to explore the possibility of moving animals to upper elevation areas. We measured survivorship, reproduction, and movements of translocated and resident animals at each site. Survivorship was not significantly different between translocated and resident animals within and among sites, and survivorship was greater overall during non-drought years. The number of eggs produced by tortoises was similar for translocated and resident females, but differed among sites. Animals translocated to atypical habitat generally moved until they reached vegetation communities more typical of desert tortoise habitat. Even within typical tortoise habitat, tortoises tended to move greater distances in the first year after translocation than did residents, but their movements in the second or third year after translocation were indistinguishable from those of resident tortoises. Our data show that tortoises translocated into typical Mojave desert scrub habitats perform well; however, the large first-year movements of translocated tortoises have important management implications. Projects that employ translocations must consider how much area will be needed to contain translocated tortoises and whether roads need fencing to prevent the loss of animals. 2012 The Wildlife Society.

Translocation could be used as a tool in conservation of the threatened Mojave Desert Tortoise ( Gopherus agassizii ) by moving individuals from harm’s way and into areas where they could contribute to conservation of the species. Numerous factors may affect the success of translocations, including the conditions experienced by tortoises in holding facilities while awaiting translocation. The tortoises available for our translocation study had been provided supplemental water during their years spent in a captive holding facility, potentially inducing carelessness in water conservation. In addition to generally investigating the efficacy of translocation, we compared the effects of continuing with the effects of ceasing the holding facility’s water supplementation regimen. After exposure to one of the two water regimens, all tortoises were given the opportunity to hydrate immediately prior to release. We examined behavior, body mass, carapace length, movement, and mortality of tortoises for two activity seasons following release to the wild. Water supplementation was correlated with high rates of carapace growth and distant movements by males after release. Lengthy movements following translocation may be problematic for conservation planning, but this should be evaluated in light of the goals and circumstances of each translocation project. Although the mortality rate was 21.4% in 1997, data suggest that drought conditions at the site rather than the translocation itself negatively affected the tortoises. None of the tortoises died during their second season at the site. Our results indicate that translocation should be considered a useful tool in conservation of the Desert Tortoise.

This paper will examine the general concept of using sludge during brick manufacture, and will specifically address the fate of metals contained within the employed sludge relative to the vitrification process. Overall, it appears that most metals will be trapped within sludge-adulterated brick, both during firing and weathering. This behavior appears related to a silicate-based physico-chemical containment mechanism. Volatilization of metal during firing was observed in the case of selenium, and in this instance only for specimens spiked with elevated metals levels (i.e. 1000 ppm Se). Simulated weathering in pH=2.5 and pH=5.0 acetic acid resulted in nominal leachate losses beyond the U.S. EPA extraction procedure limits for arsenic, selenium, and cadmium. Here again, though, these marginally elevated losses were only observed for those bricksspiked with extremely high metals levels (i.e. 1000 ppm, or higher). Overall, the research findings presented by this paper suggest that standard municipal sludges laden with “normal” metal levels could be satisfactorily incorporated within a brick manufacturing process with little concern regarding metal release. As for hazardous metal-laden sludges, brick manufacture may comprise a similarly acceptable sludge management option; however, this latter strategy would likely warrant additional site-specific investigation prior to implementation (i.e. relative to the given metal species, concentrations, metal release characteristics, etc).

A wealth of decay data has been obtained and reported in recent years, much of it in “Decay Data of the Transactinium Nuclides”. IAEA Technical Reports Series No. 261 (1986). The decay data for the daughters of 238U have been notable by their absence in such compilations and, since there is a need for such data, a set of experiments has been performed to measure their gamma-ray emission probabilities. Uranium samples of known mass and isotopic concentration were dissolved in aqueous solution, and analyzed with a high-purity germanium gamma-ray spectrometer. Some of these samples also contained multi-line calibration nuclides with well-known relative emission probabilities and the well-known emission probabilities of the 235U gamma rays were also used to provide an absolute emission probability reference. Since self-absorption of the sample was included in the effective detector efficiency, there was no need for a separate calculation of this absorption. Gamma-ray emission probabilities for the energy range 63 to 1937 keV are reported, and sources of error are discussed, including those in the efficiency curve.

A CMOS sensor array IC capable of performing fluctuation enhanced sensing for two different chemical sensing devices has been designed. The targeted sensing devices are the novel Van der Waals force enhanced MOSFET for gas and nano-particle detection and sputtered ZnO thin films as Taguchi-type sensors for gas detection. The sensor output contains information in the dynamic stochastic fluctuations around the mean value which prove useful for detection of sub-ppm concentrations of gaseous molecules. This paper discusses an implementation of fluctuation-enhanced sensing on silicon. The CMOS sensor IC consists of a low-noise transimpedance amplifier filter bank and output buffers. The circuits are all designed to operate at temperatures as high as 200/spl deg/C with low leakage currents. The overall CMOS system on chip exhibited enhanced selectivity and accuracy in providing unique signatures for gas detection.

The effect of strong shear flow on highly fluctuating lamellar systems stabilized by intermembrane collisions via the Helfrich interaction is studied. Advection enters the microscopic equation of motion for a single membrane via a non-linear coupling. Upon coarse-graining the theory for a single bilayer up to the length scale of the collision length, at which a hydrodynamic description applies, an additional dynamical coupling is generated which is of the form of a wavevector-dependent tension that is non-linear in the applied shear rate. This new term has consequences for the effects of strong flow on the stability and dynamics of lamellar surfactant phases., 17 pages, 6 figure, submitted to Phys Rev E

This report summarizes the development of an improved Human-System Interface (HSI) for space operators, and the development of a testbed for evaluating this and other new HSI concepts. This work was performed under a Small Business Innovation Research (SBIR) contract to Monterey Technologies, Inc. A task analysis was performed to identify bottlenecks in the current HSI. It was found that controllers were limited by the number of manual and visual actions required, by the organization and presentation of the data from the satellite, and limited availability of tools that aid the controller. The design of the HSI focused on elimination of these bottlenecks. The HSI developed to address these issues is multi-modal. It features voice synthesis and recognition, touchscreen capabilities, as well as a conventional keyboard and mouse interface. This HSI was implemented in a testbed that allows collection of controller performance data during a simulated support of a DSCS type satellite. The testbed architecture was designed to facilitate integration and evaluation of new, emerging HSI concepts and devices.

This report describes the work performed by Monterey Technologies, Inc. under a Phase 2 Small Business Innovation Research (SBIR) contract. The goal of the work was the development and evaluation of a novel head mounted display (HMD) that provide helicopter pilots aircraft state information in a way that allows processing by the ambient visual system. A generic helicopter simulator was built for use as a testbed. Ambient displays were presented in the pilot's peripheral field of view while the pilots performed a series of low speed flight maneuvers. The characteristics of the ambient displays were manipulated in three separate evaluations. The first evaluation focused on the size, shape, and density of the objects in the ambient display. The second experiment focused on the relationship between longitudinal motion of the aircraft and motion of the ambient objects across the display. The third experiment examined the effect of providing a horizon. In general, the presence of the ambient displays resulted in improved performance for some, but not all, flight tasks. Detailed results of these studies and recommendations for future research on the effects of ambient displays on pilot performance are presented.

We describe the design and calibration of the neutron-detection equipment used in support of the INF Treaty, and some measurements made on Soviet missiles. The fast-neutron detector, consisting of twelve 3He gas proportional tubes in a cadmium-covered polyethylene moderator, produces about 67 counts/s in a flux of neutrons from 252Cf equal to 1 neutron/cm2s. This detector is used to determine the spatial pattern of neutrons emitted from the nuclear warheads on the missiles.

We examine the degree to which field observers can meet the assumptions underlying line transect sampling to monitor populations of desert tortoises (Gopherus agassizii). We present the results of 2 field trials using artificial tortoise models in 3 size classes. The trials were conducted on 2 occasions on an area south of Las Vegas, Nevada, where the density of the test population was known. In the first trials, conducted largely by experienced biologists who had been involved in tortoise surveys for many years, the density of adult tortoise models was well estimated (-3.9% bias), while the bias was higher (-20%) for subadult tortoise models. The bias for combined data was -12.0%. The bias was largely attributed to the failure to detect all tortoise models on or near the transect centerline. The second trials were conducted with a group of largely inexperienced student volunteers and used somewhat different searching methods, and the results were similar to the first trials. Estimated combined density of subadult and adult tortoise models had a negative bias (-7.3%), again attributable to failure to detect some models on or near the centerline. Experience in desert tortoise biology, either comparing the first and second trials or in the second trial with 2 experienced biologists versus 16 novices, did not have an apparent effect on the quality of the data or the accuracy of the estimates. Observer training, specific to line transect sampling, and field testing are important components of a reliable survey. Line transect sampling represents a viable method for large-scale monitoring of populations of desert tortoise; however, field protocol must be improved to assure the key assumptions are met.

Transient events observed since 1980 by the Gamma-Ray Spectrometer experiment on the Solar Maximum Mission satellite (SMM) have been identified with radiation emitted from 18 different Soviet nuclear reactor-powered satellites. Most of these satellites are similar to Cosmos 954 and 1402 which reentered the atmosphere. Gamma radiation from these satellites was detected when they passed within about 400 to 500 kilometers of SMM. Positron annihilation line radiation (511 kiloelectron volts) and charged-particle events were detected when SMM encountered clouds of positrons and electrons emitted by these satellites and stored up to tens of minutes in the geomagnetic field. The rate of these events varied from about 1 in 5 days to over 30 per day and was strongly dependent on the operating altitudes of the Cosmos satellites and density of the upper atmosphere.

The systematic addition of alcohol to the fuel and the incorporation of a catalyst on the surface of a Cooperative Fuel Research (CFR) diesel combustion chamber significantly suppressed soot formation. These effects were additive under the experimental conditions with 40 to 80 percent soot reduction observed.

A gamma-ray detector response function model has been developed which enables computation of spectra for a variety of scintillation or high purity germanium detectors over the energy range 50 keV to 3 MeV. A set of 32 empirically determined parameters are used to describe the detector efficiency and interaction event probabilities. The model also computes the effects of scattered radiation, attenuation, coincidence event detection, and random pileup. The accuracy and general applicability of this model for a variety of detector types and configurations surpasses capabilities existing heretofore. The ability to compute accurate spectral templates is a requirement for radiochemical analysis of low resolution spectra using linear regression. An example analysis of a sodium iodide measurement of fallout from the Chernobyl nuclear reactor accident is presented. The detector response model also provides a means of computing the response of a detector to an arbitrary photon flux profile such as leakage spectrum computed by a radiation transport code.

The relative merits and sampling requirements of instrumental neutron activation analysis (INAA) and scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDS) analysis as applied to the continental component of marine aerosols are discussed. When correlated with air mass information, the quantitative INAA data on the concentrations of 15 major and minor elements in the continental dust fraction provides information on the geochemical type and location of the land source. Although the SEM/EDS technique provides only qualitative concentrations for 6 additional elements in the aerosol, the important feature of single particle analysis enables more nearly synoptic interpretation of aerosol composition and concentration. A combined INAA and SEM/EDS study of the aerosol samples is therefore preferred.

The concentrations of airborne fission products were observed to be air mass dependent during a cruise of the USNSHayes from Norfolk, Va to Athens, Greece in May–June 1977. Minimum concentrations of fission products, radon, and CCN (cloud condensation nuclei) were measured in maritime air which had previously transited northern North America. Higher fission products, radon, and CCN concentrations were measured in recent, continental air traceable to mid North America or central Europe. These data are consistent with either entrainment by strong winds of previously precipitated fission products (the ‘continental effect’) or greater transfer of fission products from the stratosphere to low levels by tropospheric folding.

A review is given of techniques for the complete automatic analysis of multichannel gamma-ray spectra from high-resolution germanium detectors, and a FORTRAN computer program is described. Previously reported fitting methods, peak shape functions, and peak search techniques are discussed. A semi-empirical peak shape is presented which gives a good fit to the variety of peak shapes and intensities which may be found in a spectrum. Equivalence is shown between a peak search using the covariance of a general peak shape with the data and a search using a general zero-area transform on the data. A comparison is made of the sensitivities of four different transforms when used in a peak search.

A study has been made of the efficiency of various techniques for use in the analysis of peaks in gamma spectra with very poor statistics. A comparison was made of the efficacy of variously shaped transforms used for smoothing and of four different zero-area transforms when used to search for very weak peaks. Results are given for computer generated data consisting of a peak on a flat background with added "random" noise. A related problem is the accurate analysis for area and position of peaks with only a few counts per channel. The standard least squares method failed to give a satisfactory fit. A simple technique is given for correcting this difficulty.

The detection of very low concentrations of tritium in the atmosphere requires rather large samples and counting times using conventional radioactive decay techniques. Substantial reductions in both sample size and counting time can be realized using accelerator mass spectrometry techniques. We have used the sector-focused cyclotron at the Naval Research Laboratory to detect tritium in hydrogen at the level of 1 part in 1012 in a 4 ml sample of hydrogen at 1 atm pressure and 15 min counting time. The detection techniques as well as improvements in beam transport efficiency and elimination of memory effects in the accelerator will be presented.

This report describes the results of an experiment to measure the natural gamma radiation emitted from the earth's surface with the aid of radiation detectors mounted in an aircraft. For comparison, two detector systems were used: an array of intrinsic germanium detectors with a total active volume of 0.4 liter and a single NaI(Tl) scintillation detector 30.5 cm diam X 30.5 cm long. Data were recorded on flights at altitudes of 60, 120, 240, 300 and 5100 meters and with average airspeed of 200 knots. A discussion is presented on the application of germanium detectors to the atmospheric radon problem; in particular, on the use of the photons with energy 295, 352 and 609 keV to determine the respective contributions from the air and the surface.

Treadmill walking endurance is the major outcome measure for intervention studies on patients with intermittent claudication. The measurement properties of this test have not, however, been well documented. We assessed the test-retest reliability of treadmill walking endurance in 10 normal subjects with a mean (+/- 1SD) age of 27.5 (+/- 3.3) years. On four occasions, at intervals of at least one week, each subject walked on a motorized treadmill to the limits of his or her capabilities. With the standard protocol, subjects began at a very low exercise intensity (0.25 m/sec, 0% grade), which increased in either speed or grade at ninety-second intervals through a maximum of fifteen stages to 2.75 m/sec and 20% grade. On the final occasion, 5 of the subjects were tested twice with a fifteen-minute interval, using a truncated protocol starting at stage five (1.25 m/sec, 0% grade). Within-subject standard deviations were low, averaging twenty-three seconds (2.1%). Reliability was very high for the first three tests with the standard protocol (r greater than or equal to 0.98, p less than 0.0001) and for the 5 subjects tested and retested with the short interval and truncated protocol (r = 0.99, p less than 0.0002), while the correlation between the standard protocol and the truncated protocol was somewhat lower (r greater than 0.81, p less than 0.01). For young normal subjects the measurement of walking endurance with an incremental treadmill test is highly reliable, but the limits of reliability need to be considered when conclusions are drawn from such measures.

The pressure within exercising skeletal muscle rises and falls rhythmically during normal human locomotion, the peak pressure reaching levels that intermittently impede blood flow to the exercising muscle. Speculating that a reciprocal relationship between the timing of peak intramuscular and pulsatile arterial pressures should optimize blood flow through muscle and minimize cardiac load, we tested the hypothesis that heart rate becomes entrained with walking and running cadence at some locomotion speeds, by means of electrocardiography and an accelerometer to provide signals reflecting heart rate and cadence, respectively. In 18 of 25 subjects, 1:1 coupling of heart and step rates was present at one or more speeds on a motorized treadmill, generally at moderate to high exercise intensities. To determine how exercise specific this phenomenon is, and to refute the competing hypothesis that coupling is due to vertical accelerations of the heart during locomotion, we had 12 other subjects cycle on an electronically braked bicycle ergometer. Coupling was found between heart rate and pedaling frequency in 10 of them. Cardiac-locomotor coupling appears to be a normal physiological phenomenon, and its identification provides a fresh perspective from which to study endurance.

We examined the hypothesis that anterior tibial intramuscular pressure increases with the speed of locomotion. A solidstate pressure transducer was placed near the tip of an intramuscular fluid-filled catheter and each of ten normal subjects walked, jogged and ran barefoot, at 1.5, 2.5 and 3.5 m s-1 respectively, on a treadmill to which they had been previously familiarized. The pressure signals during ten gait cycles from each subject were sampled at 600 Hz and were averaged at each speed. The peak pressures increased in magnitude as a function of increasing locomotion speed, while the mean pressure remained constant.