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Supersonic civil aircraft present a unique noise certification challenge. High specific thrust required for supersonic cruise results in high engine exhaust velocity and high levels of jet noise during take-off. Aerodynamics of thin, low-aspect-ratio wings equipped with relatively simple flap systems deepen the challenge. Advanced noise reduction procedures have been proposed for supersonic aircraft. These procedures promise to reduce certification noise levels, but they may require departures from normal reference procedures defined in noise regulations. The subject of this article is a take-off performance and noise assessment of a notional supersonic business jet. Analytical models of an airframe and a supersonic engine derived from a contemporary subsonic turbofan core are developed. These models are used to predict take-off trajectories and certification noise levels. Results indicate advanced take-off procedures are helpful in reducing noise along lateral sidelines.
Using speakers of either African American English or Southern White English, we asked whether a working memory measure was linguistically unbiased, that is, equally able to distinguish between children with and without specific language impairment (SLI) across dialects, with similar error profiles and similar correlations to standardized test scores. We also examined whether the measure was affected by a child's nonmainstream dialect density. Fifty-three kindergarteners with SLI and 53 typically developing controls (70 African American English, 36 Southern White English) were given a size judgment working memory task, which involved reordering items by physical size before recall, as well as tests of syntax, vocabulary, intelligence, and nonmainstream density. Across dialects, children with SLI earned significantly poorer span scores than controls, and made more nonlist errors. Span and standardized language test performance were correlated; however, they were also both correlated with nonmainstream density. After partialing out density, span continued to differentiate the groups and correlate with syntax measures in both dialects. Thus, working memory performance can distinguish between children with and without SLI and is equally related to syntactic abilities across dialects. However, the correlation between span and nonmainstream dialect density indicates that processing-based verbal working memory tasks may not be as free from linguistic bias as often thought. Additional studies are needed to further explore this relationship.
Previous studies have highlighted the role of the brain reward and cognitive control systems in the etiology of anorexia nervosa (AN). In an attempt to disentangle the relative contribution of these systems to the disorder, we used functional magnetic resonance imaging (fMRI) to investigate hemodynamic responses to reward-related stimuli presented both subliminally and supraliminally in acutely underweight AN patients and age-matched healthy controls (HC).
fMRI data were collected from a total of 35 AN patients and 35 HC, while they passively viewed subliminally and supraliminally presented streams of food, positive social, and neutral stimuli. Activation patterns of the group×stimulation condition×stimulus type interaction were interrogated to investigate potential group differences in processing different stimulus types under the two stimulation conditions. Moreover, changes in functional connectivity were investigated using generalized psychophysiological interaction analysis.
AN patients showed a generally increased response to supraliminally presented stimuli in the inferior frontal junction (IFJ), but no alterations within the reward system. Increased activation during supraliminal stimulation with food stimuli was observed in the AN group in visual regions including superior occipital gyrus and the fusiform gyrus/parahippocampal gyrus. No group difference was found with respect to the subliminal stimulation condition and functional connectivity.
Increased IFJ activation in AN during supraliminal stimulation may indicate hyperactive cognitive control, which resonates with clinical presentation of excessive self-control in AN patients. Increased activation to food stimuli in visual regions may be interpreted in light of an attentional food bias in AN.
A cereal rye cover crop mulch can suppress summer annual weeds early in the soybean growing season. However, a multi-tactic weed management approach is required when annual weed seedbanks are large or perennial weeds are present. In such situations, the weed suppression from a cereal rye mulch can be supplemented with the use of high-residue cultivators which can prolong the weed-free period during soybean growth. Research trials were conducted to determine the optimum timing of high-residue cultivation for weed control in rolled-crimped cereal rye mulches. Treatments included three cultivation timings with a high-residue cultivator: early (3-4 wk after soybean planting (WAP)), intermediate (5-6 WAP), and late (7-8 WAP), a weed-free and no-cultivation control. Crop and weed measurement included cereal rye biomass, weed biomass, soybean population and biomass, and yield. Cereal rye biomass was 50% lower and weed biomass was three times greater in 2011 than in 2010 and 2012 due to 2011 being a dry year. There was no significant effect of cultivation timing on soybean population when compared to no-cultivation or hand-weeded treatments. While cultivation reduced weed biomass by 67% compared to no-cultivation, soybean yield was only improved by 12% in early and late cultivation treatments and 22% in intermediate cultivation treatment when compared to no-cultivation. Effective strategies for improving weed management by integrating the use of a high-residue cultivator in no-till organic systems could help existing organic field crop producers to reduce tillage while also encourage adoption of organic crop production by conventional growers who prefer reduced-tillage systems. Unlike traditional organic cultivation equipment, therefore, optimal timing of cultivation should be delayed several weeks in organic cover crop-based no-till planted soybean production as compared to the typical tillage-based approach to ensure both weed control and optimal yield.
The role of the magnetic field in a coronal mass ejection event has not been unequivocally defined, and may in fact be quite variable in view of the large variety of shapes and sizes of coronal transients. Measurements of the magnetic field associated with these events have thus far been inferred from simultaneously observed radio bursts, which provide no information on the direction of the field and are limited in spatial resolution. Substantial improvement in these two areas could be achieved by continuous monitoring of the Faraday rotation of a linearly polarized spacecraft signal during solar occultation. A coronal event traversing the line-of-sight would yield a characteristic profile in cross section, which would be of value for discriminating between the various models of coronal transients.
Patients with anorexia nervosa (AN) are characterized by a very low body weight but readily give up immediate rewards (food) for long-term goals (slim figure), which might indicate an unusual level of self-control. This everyday clinical observation may be quantifiable in the framework of the anticipation-discounting dilemma.
Using a cross-sectional design, this study compared the capacity to delay reward in 34 patients suffering from acute AN (acAN), 33 weight-recovered AN patients (recAN) and 54 healthy controls. We also used a longitudinal study to reassess 21 acAN patients after short-term weight restoration. A validated intertemporal choice task and a hyperbolic model were used to estimate temporal discounting rates.
Confirming the validity of the task used, decreased delay discounting was associated with age and low self-reported impulsivity. However, no group differences in key measures of temporal discounting of monetary rewards were found.
Increased cognitive control, which has been suggested as a key characteristic of AN, does not seem to extend the capacity to wait for delayed monetary rewards. Differences between our study and the only previous study reporting decreased delay discounting in adult AN patients may be explained by the different age range and chronicity of acute patients, but the fact that weight recovery was not associated with changes in discount rates suggests that discounting behavior is not a trait marker in AN. Future studies using paradigms with disorder-specific stimuli may help to clarify the role of delay discounting in AN.
We study the stellar content of three galactic bulges with the high resolution gratings (R=7000) of the WiFeS integral field unit in order to better understand their formation and evolution. In all cases we find that at least 50% of the stellar mass already existed 12 Gyrs ago, more than currently predicted by simulations. A younger component (age between ∼1 to ∼8 Gyrs) is also prominent and its present day distribution seems to be much more affected by morphological structures, especially bars, than the older one. This in-depth analysis supports the notion of increasing complexity in bulges which cannot be achieved by mergers alone, but requires a non-negligible contribution from secular evolution.
This study examined everyday action impairment in participants with Parkinson's disease dementia (PDD) by comparison with participants with Parkinson's disease-no dementia (PD) or Alzheimer's disease (AD) and in reference to a neuropsychological model. Participants with PDD (n = 20), PD (n = 20), or AD (n = 20) were administered performance-based measures of everyday functioning that allowed for the quantification of overall performance and error types. Also, caregiver ratings of functional independence were obtained. On performance-based tests, the PDD group exhibited greater functional impairment than the PD group but comparable overall impairment relative to the AD group. Error patterns did not differ between PDD and PD participants but the PDD group demonstrated a higher proportion of commission errors and lower proportion of omission errors relative to the AD group. Hierarchical regression analyses showed omission errors were significantly predicted by neuropsychological measures of episodic memory, whereas commission errors were predicted by both measures of general dementia severity (MMSE) and executive control. Everyday action impairment in PDD differs quantitatively from PD but qualitatively from AD and may be characterized by a relatively high proportion of commission errors—an error type associated with executive control deficits. (JINS, 2012, 18, 1–12)
Aluminum nitride (AlN) thin films were deposited from trimethyl aluminum (TMA) and Ammonia (NH3) by thermal atomic layer deposition (thermal ALD) and plasma enhanced atomic layer deposition (PEALD) on 200 mm silicon wafers. For both thermal ALD and PEALD, the deposition rate increased significantly with the deposition temperature. The deposition rate did not fully saturate even with 10 seconds of NH3 pulse time. Plasma significantly increased the deposition rate of AlN films. A large number of incubation cycles were needed to deposit AlN films on Si wafers. 100% step coverage was achieved on trenches with aspect ratio of 35:1 at 100 nm feature size by thermal ALD. X-ray diffraction (XRD) data showed that the AlN films deposited from 370 °C to 470 °C were polycrystalline. Glancing angle X-ray reflection (XRR) results showed that the RMS roughness of the films increased as the film thickness increased.
This paper reviews the basis for phenomenological path for gettering: release, diffusionand capture in the context of old and new developments. More recent precipitation studies in silicon are now recognized to involve complex interactive effects. Controlled precipitation requires knowledge of and control of not only oxygen but carbon, native defects(related to crystal thermal history and/or process history), high doping, microfluctuations and interactions between “extrinsic” and “intrinsic” gettering.
In the first part of this paper the role of rapid thermal annealing in sulicide processing is viewed from a theoretical point of view with respect to what is known about metal-silicon reactions. The second part is a brief survey of the quickly expanding literature on the rapid thermal annealing of silicides. Whereas RTA does not appear to solve all, or perhaps even any, of the problems encountered in the use of silicides, it is concluded that RTA presents a number of definite advantages.
DLTS measurements show that majority-carrier traps exist after quartz-lamp, rapid-thermal annealing (RTA) activation of B+ and BF2+ ion implants in n-type silicon. Levels at Ec-0.17, 0.27, 0.44 and 0.57 eV annealed out with an additional 20 minute isochronal anneal at 550°C in argon. A stable defect at 0.37 eV existed at temperatures above 750°C. DLTS measurements of a Schottky diode on n-type silicon after only RTA indicated that electron traps could be introduced into n-type silicon by the RTA alone.
W-Ti bilayers on Si have been processed by fast thermal annealing in air, in N2/H2 (5%), and vacuum (1 E-3 and 1 E-6 Torr). The results indicate that the W layer on top of Ti acts as an effective protection barrier against oxidation of Ti in all atmospheres except air. Titanium-rich silicides are formed after 500 °C, while TiSi2 is completed at about 600 °C. At 700 °C a bilayer of WSi2/TiSi2 is found. Silicon is found to be the diffusing specie during the formation of WSi2. Finally, a ternary silicide, Ti0.6W0.4Si2, starts to form after 780 °C. The final ternary silicide phase has'an Mlectrical resistivity of about 60 μΩ-cm.
A comprehensive review is presented of the use of transient thermal processing for the activation of implanted dopants, the alloying of ohmic contacts, the pulse diffusion of Zn for p+ contacts, and other heat treatments of GaAs. In all cases, transient processing produces results at least as good as furnace heating, and in some instances, markedly better. The special needs of GaAs, such as encapsulation of the wafer surface, and prevention of slip and warpage are discussed, as well as recent results detailing implant damage removal processes during transient annealing.
This study describes the use of a steam environment to reflow phosphosilicate glass (PSG) samples using a HEATPULSE® rapid thermal annealer. The samples comprised PSG over poly steps and of open contacts in PSG. It was observed that reflow occurs 50°C lower in steam than in dry O2. An acceptable flow cycle for 8 w/o P in PSG glass is 1050°C for 10 seconds in steam, while for 6 w/o P PSG it is 1100°C for 10 seconds. Steam is found to be an effective amibient for densification of the PSG film. The thermal oxide grown in the contact during opening reflow was determined to be near 140 A. The operating regime for a junction depth <0.4 um and a reflow angle < 75° is presented for 8 w/o P.
This bibliography presents 342 references to work published on rapid thermal processing (RTP) from 1979 through mid-1985. A variety of broad-beam energy sources are represented, including: arc and quartz-halogen lamps, blackbody radiators, strip heaters, broadly rastered electron beams, and defocused CO2 lasers. Citations were obtained by both manual searching and searching of a commercially available computerized data base (I NSPEC). Entries are grouped under 13 topical headings: reviews, implanted dopant activation and diffusion in silicon, polycrystalline silicon, silicides and polycides, metals, dielectrics, compound semiconductors, defects and microstructure, device applications (silicon and compound semiconductors), miscellaneous applications, equipment, and modeling. Within each group, citations are arranged alphabetically by title. A full author index is provided.