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Synthesizing thin diamond films by chemical vapor deposition (CVD) is the most recent and technologically important development in the thin-film field. Thin diamond films are useful in many applications because of their unique physical, chemical, optical, and electronic properties.
To assess thin diamond films’ suitability for support membranes in X-ray lithography, X-ray diffraction was used to characterize the crystal structure and orientation of these films deposited on silicon wafers by hot-filament assisted CVD. X-ray transmission properties of free-standing thin diamond films prepared by selectively etching silicon substrates were characterized by X-ray fluorescence in short and long wavelength regions.
This paper discusses conventional and grazing incidence diffraction techniques used to study the crystal structure of thin diamond films and compares the results with film morphology. It also describes X-ray transmission properties of these films in terms of Beer's Law, the mass absorption coefficient, and the wavelength of attenuated radiation. Finally, it reveals the long wavelength regions for optimum X-ray lithography operations using polycrystalline diamond (PCD) film.
M. M. Hedman, University of Idaho Moscow, Idaho, USA,
F. Postberg, University of Heidelberg Heidelberg, GERMANY,
D. P. Hamilton, University of Maryland College Park, Maryland, USA,
S. Renner, University of Lille Lille, FRANCE,
H.-W. Hsu, University of Colorado Boulder, Colorado, USA
All of the giant planets in the outer Solar System possess rings composed primarily of particles less than 100 microns across. Such small particles are conventionally referred to as “dust grains” regardless of their composition, and so these rings are considered “dusty rings” (as opposed to the more famous main rings of Saturn and Uranus, whose particles are more than a millimeter across). Dusty rings are often very tenuous and so can be much more difficult to observe than Saturn's broad, bright, and dense main rings. Nevertheless, dusty rings are extremely interesting because they have very rich dynamics and are extremely sensitive probes of their environment.
The high surface-area-to-volume ratio of dust-sized grains makes them much more responsive to non-gravitational forces like solar radiation pressure, plasma drag, and torques from the planet's electromagnetic field. Furthermore, sub-millimeter particles can be lost from the ring system on relatively short timescales due to erosion via charged-particle and micrometeoroid bombardment or through ejection by the non-gravitational forces listed above. This means that small particles need to be constantly supplied to these rings from larger bodies, and indeed all of the known dusty rings are associated with larger objects that are the likely sources of dusty debris. The most dramatic example of this is Saturn's E ring, which is clearly supplied by material erupting from beneath the surface of the geologically active moon Enceladus. However, this is a special case, and most dusty rings are instead associated with denser rings (which are composed primarily of millimeter-to-metersized particles) or small moons. These objects can serve as dust sources because they are constantly being bombarded by micrometeoroids, and these impacts release fine debris that can escape the weak gravitational fields of these small bodies and go into orbit around the planet. Note that the amount of dust released by this process depends on the size, mass, and regolith properties of the source object, and calculations of the dust production rate based on simple estimates of impact ejecta velocity distributions suggest that source moons that are several kilometers across are the most efficient at producing dusty rings (Burns et al., 1999).
Bòbila Madurell-Can Gambús is the most emblematic Neolithic cemetery in the northeastern Iberian peninsula, with a total of 179 documented pit burials. Artifacts made of exogenous raw materials, such as honey flint (southeastern France), jadeite, amphibolite, eclogite and nephrite (Alps and the Pyrenees), variscite (coast of northeastern Iberia), and even obsidian (Sardinia), have been found in the burials. The presence of these raw materials is not exclusive to this necropolis, but they have also been documented in many of the graves of this region during this period. The literature has singled out this funerary practice as the Pit Burials cultural horizon. However, until now the chronology of this funerary practice has not been fully defined, so it was difficult to explain the development of the chronology and the networks through which the materials reached northeast Iberia. New, unpublished radiocarbon (14C) dates of Bòbila Madurell-Can Gambús are presented, as well as the results of different statistical analyses and Bayesian modeling that specify its chronology. Through the contribution of new data on the chronology of Bòbila Madurell-Can Gambús new clues regarding the temporal dynamics of pit burials and the raw materials exchange networks associated with them are presented.
Pale soft exudative pork (PSE) is a major problem affecting swine industries worldwide that results in significant economic loss because it reduces processing and saleable product yields. The PSE condition results from a rapid rate of muscle glycolysis early postmortem and a rapid drop in muscle pH while the temperature of the carcass is still high. Stress prior to slaughter can increase the rate of glycolysis and postmortem acidification. Blood acid-base has been used as an indicator of stress in pigs. The objective of this experiment was to investigate the relationship between blood acid-base status at slaughter and fresh meat quality in pigs.
We present preliminary analysis of new HST observations of the transiting extrasolar planet HD 209458b. Photometric observations were obtained with the Fine Guidance Sensor (FGS) on the Hubble Space Telescope (HST), providing milli-mag precision and high time resolution (40 Hz). The FGS photometry allows us to derive precise stellar/orbital parameters (ephemeris, inclination, limb darkening) and planetary radius, and also allows a search for the presence of planetary rings and satellites. We discuss preliminary results and two approaches to modelling the observations.
The relic “the sack of Saint Francesco” has for the first time been investigated by scientific means. The sack is kept at the Franciscan Friary of Folloni near Montella in southern Italy. According to legend, the sack appeared on the doorstep of the Friary in the winter of 1224 containing bread sent from St Francesco (St Francis of Assisi), who at that time was in France. The bread was allegedly brought to the friary by an angel. We analyzed samples of the sack to obtain a radiocarbon (14C) date and to search for any remaining traces of bread. The 14C date yielded a calibrated age range of AD 1220–1295 (2σ), which places the textile in the right timeframe according to the legend. Chemical analysis by gas-chromatography with mass spectrometric detection (GC-MS) revealed the presence of ergosterol (5, 7, 22-ergostatrien-3b-ol), a known biomarker of brewing, baking, or agriculture. In this paper we have further substantiated the validity of ergosterol as a biomarker for the past presence of bread. It appears that there is a fine correspondence between the Franciscan legend and the two most decisive scientific methods relevant for analyzing the sack. Although it is not proof, our analysis shows that the sack indeed could be authentic.
An updated compilation of published and new data of major-ion (Ca, Cl, K, Mg, Na, NO3, SO4) and methylsulfonate (MS) concentrations in snow from 520 Antarctic sites is provided by the national ITASE (International Trans-Antarctic Scientific Expedition) programmes of Australia, Brazil, China, Germany, Italy, Japan, Korea, New Zealand, Norway, the United Kingdom, the United States and the national Antarctic programme of Finland. The comparison shows that snow chemistry concentrations vary by up to four orders of magnitude across Antarctica and exhibit distinct geographical patterns. The Antarctic-wide comparison of glaciochemical records provides a unique opportunity to improve our understanding of the fundamental factors that ultimately control the chemistry of snow or ice samples. This paper aims to initiate data compilation and administration in order to provide a framework for facilitation of Antarctic-wide snow chemistry discussions across all ITASE nations and other contributing groups. The data are made available through the ITASE web page (http://www2.umaine.edu/itase/content/syngroups/snowchem.html) and will be updated with new data as they are provided. In addition, recommendations for future research efforts are summarized.
OBJECTIVES/SPECIFIC AIMS: The objective of this research was to investigate the effect of alcohol and evocative stimuli on heart rate variability (HRV) in partners with a history of intimate partner violence in a placebo-controlled alcohol administration study with an emotion-regulation task. METHODS/STUDY POPULATION: In total, 17 partners (9 females, 8 males) with a history of partner violence participated in a placebo-controlled alcohol administration study with an emotion-regulation task during which HRV measures were collected. In the alcohol condition, participants were administered a mixture of 100 proof vodka and cranberry juice calculated to raise their blood alcohol concentration (BAC) to 0.08%. In the placebo condition, participants consumed a volume of juice equivalent to that consumed in the alcohol condition, but without alcohol. Alcohol and placebo conditions were counter-balanced across participants as were the presentation the blocks of evocative and neutral partner stimuli. RESULTS/ANTICIPATED RESULTS: Controlling for baseline HRV, there was a significant main effect of stimuli (evocative vs. neutral partner stimuli) on HRV in intoxicated partners, F1,16=16.28, p=0.004. There was also a significant main effect of regulation on HRV under conditions acute alcohol intoxication, F1,16=23.55, p=0.001. These effects tell us that intoxicated partners experienced reduced HRV when exposed to evocative stimuli from their partners. These effects also tell us that under acute alcohol intoxication, partners were less able to regulate their emotion when exposed to evocative stimuli than when they consumed a placebo beverage. DISCUSSION/SIGNIFICANCE OF IMPACT: These results suggest that increases in intimate partner violence under acute alcohol intoxication may be the result of reduce HRV. This reduction in HRV would contribute to partners’ inability to response with adaptively in conflict when intoxicated. They also suggest that HRV may be an important target for intervention with partner with a history of intimate partner violence. One method may be Heart Rate Variability Biofeedback which has been shown to increase parasympathetic nervous system functioning, autonomic stability, and emotion regulation.
Six radio telescopes were operated as the first southern hemisphere VLBI array in April and May 1982. Observations were made at 2.3 and 8.4 Ghz. This array produced VLBI images of 28 southern hemisphere radio sources, high accuracy VLBI geodesy between southern hemisphere sites, and subarcsecond radio astrometry of celestial sources south of declination −45 degrees. This paper discusses only the astrophysical aspects of the experiment.
VLBI observations of the nucleus of Centaurus A were made in April, 1982 at two frequencies with an array of five Australian radio antennas as part of the Southern Hemisphere VLBI Experiment (SHEVE). Observations were undertaken at 2.29 GHz with all five antennas, while only two were operational at 8.42 GHz. The 2.29 GHz data yielded significant information on the structure of the nuclear jet. At 8.42 GHz a compact unresolved core was detected as well.
Targets have been developed to measure supersonic radiation transport in aerogel foams using absorption spectroscopy. The target consists of an aerogel foam uniformly doped with either titanium or scandium inserted into an undoped aerogel foam package. This creates a localized doped foam region to provide spatial resolution for the measurement. Development and characterization of the foams is a key challenge in addition to machining and assembling the two foams so they mate without gaps. The foam package is inserted into a beryllium sleeve and mounted on a gold hohlraum. The target is mounted to a holder created using additive manufacturing and mounted on a stalk. The manufacturing of the components, along with assembly and metrology of the target are described here.
We investigate the role of distal, proximal, and child risk factors as predictors of reading readiness and attention and behavior in children at risk of dyslexia. The parents of a longitudinal sample of 251 preschool children, including children at family risk of dyslexia and children with preschool language difficulties, provided measures of socioeconomic status, home literacy environment, family stresses, and child health via interviews and questionnaires. Assessments of children's reading-related skills, behavior, and attention were used to define their readiness for learning at school entry. Children at family risk of dyslexia and children with preschool language difficulties experienced more environmental adversities and health risks than controls. The risks associated with family risk of dyslexia and with language status were additive. Both home literacy environment and child health predicted reading readiness while home literacy environment and family stresses predicted attention and behavior. Family risk of dyslexia did not predict readiness to learn once other risks were controlled and so seems likely to be best conceptualized as representing gene–environment correlations. Pooling across risks defined a cumulative risk index, which was a significant predictor of reading readiness and, together with nonverbal ability, accounted for 31% of the variance between children.
Structural brain magnetic resonance imaging (MRI) traits share part of their genetic variance with cognitive traits. Here, we use genetic association results from large meta-analytic studies of genome-wide association (GWA) for brain infarcts (BI), white matter hyperintensities, intracranial, hippocampal, and total brain volumes to estimate polygenic scores for these traits in three Scottish samples: Generation Scotland: Scottish Family Health Study (GS:SFHS), and the Lothian Birth Cohorts of 1936 (LBC1936) and 1921 (LBC1921). These five brain MRI trait polygenic scores were then used to: (1) predict corresponding MRI traits in the LBC1936 (numbers ranged 573 to 630 across traits), and (2) predict cognitive traits in all three cohorts (in 8,115–8,250 persons). In the LBC1936, all MRI phenotypic traits were correlated with at least one cognitive measure, and polygenic prediction of MRI traits was observed for intracranial volume. Meta-analysis of the correlations between MRI polygenic scores and cognitive traits revealed a significant negative correlation (maximal r = 0.08) between the HV polygenic score and measures of global cognitive ability collected in childhood and in old age in the Lothian Birth Cohorts. The lack of association to a related general cognitive measure when including the GS:SFHS points to either type 1 error or the importance of using prediction samples that closely match the demographics of the GWA samples from which prediction is based. Ideally, these analyses should be repeated in larger samples with data on both MRI and cognition, and using MRI GWA results from even larger meta-analysis studies.
This investigation examined the relationship between teachers’ beliefs and their preferences for classroom interventions for behaviours consistent with attention-deficit/hyperactivity disorder (ADHD). Teacher ratings of intervention acceptability, effectiveness, and rate of change were compared across United States and New Zealand samples. Beliefs examined were personal teaching efficacy, general teaching efficacy, and pupil control ideology (PCI). Samples were compared regarding their preferences for the daily report card, response cost technique, classroom lottery, and medication as classroom strategies for managing ADHD-related behavioural concerns. Data were analysed using general linear modelling techniques, and an interaction was demonstrated between ADHD intervention x PCI x nationality. Differences were observed for ADHD interventions across samples based upon pupil control orientations. Implications for educators and their classroom practices are discussed.
In this paper, high temperature (>1400°C) thermal oxidation has been applied, for the first time, to 4H-SiC PiN diodes with thick (110 μm) drift regions, for the purpose of increasing the carrier lifetime in the semiconductor. PiN diodes were fabricated using 4H-SiC material that had undergone thermal oxidation performed at 1400°C, 1500°C and 1600°C, then were electrically characterized. Forward current-voltage (I-V) measurements showed that thermally oxidized PiN diodes exhibited considerably improved electrical characteristics, with devices oxidized at 1500°C having a forward voltage drop (VF) of 4.15 V and a differential on-resistance (Ron,diff) of 8.9 mΩ-cm2 at 100 A/cm2 and 25°C. Compared to typical control sample PiN diode characteristics, this equated to an improvement of 8% and 23% for VF and Ron,diff, respectively. From analysis of the reverse recovery characteristics, the carrier lifetime of the PiN diodes oxidized at 1500°C was found to be 1.05 μs, which was an improvement of around 30% compared to the control sample PiN diodes.
Silicon carbide power devices are purported to be capable of operating at very high temperatures. Current commercially available SiC MOSFETs from a number of manufacturers have been evaluated to understand and quantify the aging processes and temperature dependencies that occur when operated up to 350°C. High temperature constant positive bias stress tests demonstrated a two times increase in threshold voltage from the original value for some device types, which was maintained indefinitely but could be corrected with a long negative gate bias. The threshold voltages were found to decrease close to zero and the on-state resistances increased quite linearly to approximately five or six times their room temperature values. Long term thermal aging of the dies appears to demonstrate possible degradation of the ohmic contacts. This appears as a rectifying response in the I-V curves at low drain-source bias. The high temperature capability of the latest generations of these devices has been proven independently; provided that threshold voltage management is implemented, the devices are capable of being operated and are free from the effects of thermal aging for at least 70 hours cumulative at 300°C.
A model is proposed for predicting the presence of cumulative nonlinear distortions in the acoustic waveforms produced by high-speed jet flows. The model relies on the conventional definition of the acoustic shock formation distance and employs an effective Gol’dberg number
for diverging acoustic waves. The latter properly accounts for spherical spreading, whereas the classical Gol’dberg number
is restricted to plane wave applications. Scaling laws are then derived to account for the effects imposed by jet exit conditions of practical interest and includes Mach number, temperature ratio, Strouhal number and an absolute observer distance relative to a broadband Gaussian source. Surveys of the acoustic pressure produced by a laboratory-scale, shock-free and unheated Mach 3 jet are used to support findings of the model. Acoustic waveforms are acquired on a two-dimensional grid extending out to 145 nozzle diameters from the jet exit plane. Various statistical metrics are employed to examine the degree of local and cumulative nonlinearity in the measured waveforms and their temporal derivatives. This includes a wave steepening factor (WSF), skewness, kurtosis and the normalized quadrature spectral density. The analysed data are shown to collapse reasonably well along rays emanating from the post-potential-core region of the jet. An application of the generalized Burgers equation is used to demonstrate the effect of cumulative nonlinear distortion on an arbitrary acoustic waveform produced by a high-convective-Mach-number supersonic jet. It is advocated that cumulative nonlinear distortion effects during far-field sound propagation are too subtle in this range-restricted environment and over the region covered, which may be true for other laboratory-scale jet noise facilities.
I have always found mathematics interesting and enjoyable. It is also my great fortune to have a job that touches some facet of mathematics virtually every day. I work at the Kodak Research Labs as an industrial mathematician, which means that I am a problem solver. Currently, I am developing new algorithms for Kodak's digital camera program, a task I find both challenging and rewarding. It is satisfying to know that I had a direct hand in developing or improving many Kodak digital cameras on the market today.
Before my current assignment I worked in diverse problem areas such as optics, medical imaging, graphic arts (commercial printing), and laser printers. In each case, I used mathematical models and computational methods to answer a question or solve an engineering problem. I found my mathematics qualifications to be a stepping stone into a whole spectrum of interesting engineering applications.
In industry, the purpose of building mathematical models is to save time and money. In one of my projects, an optical filter had to be designed for a camera. One way to proceed was by trial and error. We could make a filter, test it, and decide how to modify it for the next trial. Each complete trial cycle would take about two weeks, and it could take dozens of trials to get an acceptable filter. Once the mathematical model was developed, the optical performance of any filter design could be computed in just 15 minutes.