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91.
Ha J.H. Kim S.W. Seol Y.S. Park H.K. Choi S.H. 《Semiconductor Manufacturing, IEEE Transactions on》1996,9(2):289-291
The plug loading effect occurring during the etchback of tungsten was investigated in a magnetically enhanced reactive ion etcher using SF 6/Ar mixtures. It was found that while the plug loading effect is independent of varying SF6/Ar flow rate ratio and magnetic field intensity, it is reduced under the condition of high selectivity of tungsten relative to TiN which was achieved at high chamber pressure and low RF power. It is proposed that when TiN is used as a glue layer, the W etch rate enhancement in the plug is mainly controlled by a local loading effect. Under the optimized etchback conditions the plug loss was successfully controlled without the tungsten residue left on severe topology 相似文献
92.
Postembryonic neurogenesis leads to a dramatic increase in the number of functional neurons within the segmental ganglia of the moth, Manduca sexta. These adult-specific neurons are generated during larval life by segment-specific arrays of individually identifiable stem cells, or neuroblasts (Nbs). By the end of the feeding larval stage, each Nb has generated a discrete nest of progeny, which ranges in size from less than 10 to more than 70 progeny. The sizes of these identifiable nests of progeny vary in a segment-specific manner, with the thoracic nests containing a greater number of progeny compared with their homologues in the simpler abdominal ganglia. In order to describe those factors that influence the size of the post-embryonic neuronal lineages, we examined the spatial and temporal pattern of postembryonic neurogenesis in the segmental ganglia of Manduca. The rates at which the identifiable nests accumulated progeny were estimated by counting the number of progeny within the nests, using sectioned material isolated from animals at stages ranging from embryonic hatching until the end of the feeding larval stage. All of the postembryonic Nbs began to generate progeny at around the time of the molt to the third larval instar. Each nest added progeny at a rate that was a characteristic of its identity and segment of origin. Although all of the nests within the thorax continued to accumulate progeny throughout the feeding larval stage, several of the abdominal nests showed little or no growth following the molt to the fifth larval instar. The thymidine analog 5-bromo 2-deoxyuridine (5-BrdU) was used to estimate the mitotic rates of the identifiable Nbs. The number of labeled progeny within a nest 24 h after application of 5-BrdU ranged from a low of 1 to 2 to a high of 11 to 13 labeled cells. In some instances there was a good correlation between the estimated mitotic rate of an identified Nb and the rate of growth of its associated nest of progeny. However, several of the identifiable nests accumulated progeny at a slower rate than predicted based on the estimated mitotic rate of the Nb. Cell death appears to be responsible for slowing the growth of the nests during the feeding larval stage. We estimate that 10% to 70% of the neurons generated during the feeding larval stage degenerate within 24 h of their birth. The level of cell death observed within a nest was dependent on both its identity and its segment of origin. 相似文献
93.
The Center for NDE, Iowa State University, has developed a laboratory prototype Golay code pulse compression system and tested
it on a variety of materials. The performance of the system was evaluated in terms of signal-to-noise ratio enhancement (SNRE),
resolution, and computation speed. The system's error sources also were discussed. The Golay code pulse compression was simulated
on a computer and demonstrated the effective noise suppression. In addition, an equivalent pulse of the Golay code (delta-like
pulse) was derived theoretically using a simple ultrasonic inspection model, which demonstrated its equivalence on the output
correlated signal. Overall, the pulse compression technique extended the detection range for a given peak power and considerably
reduced the system'swhite noise, hence providing enhanced signal-to-noise ratios (SNRs). An average of 30 dB improvement in SNR was obtained from highly
energy-absorbent materials such as rubber, plastics, corks (insulation materials), and thick composites using the Golay codes
of up to 512 bits. However, the technique did not effectively reduce coherent scattering noises from the coarse grain boundaries
in cast stainless steels, Inconel weld metal, and material lay-ups in thin composites. Furthermore, it was found that, depending
upon the system's hardware capabilities, the overall performance could be degraded considerably. 相似文献
94.
BACKGROUND: Increases in acetylcholine receptors (AChRs) at the muscle membrane, induced by burn injury, have been associated with a hyperkalemic response to succinylcholine and resistance to d-tubocurarine-like drugs. Muscle relaxants often are administered to burn-injured patients in the intensive care unit to facilitate mechanical ventilation. This study in rats tested whether continuous administration of d-tubocurarine in subparalytic doses exaggerates the upregulation of AChRs induced by burn trauma. Subparalytic doses were used to avoid the confounding effects of immobilization. METHODS: Three days after an approximate 50% body surface area burn or sham injury, the animals received an infusion of 3.03 +/- 0.05 micrograms/h of d-tubocurarine or equal volume of saline directly to the left gastrocnemius muscle via catheter connected to a subcutaneously implanted osmotic pump. After 7 days of d-tubocurarine or saline infusion, the AChRs were quantitated using 125I-alpha-bungarotoxin. The AChRs on the d-tubocurarine or saline-infused left gastrocnemius were compared to the contralateral gastrocnemius in the same group. The right or left gastrocnemius AChRs were compared to the ipsilateral muscles between groups. These intra- and intergroup comparisons allowed the delineation of the effects of catheter irritation, burns, or d-tubocurarine on AChRs. RESULTS: Daily examination of the withdrawal response to toe-pinch revealed no evidence of paralysis. Weight loss in the burn-injury animals receiving d-tubocurarine or saline was similar, confirming that the infusion of d-tubocurarine did not impair the mobility of the animals to move and feed. The plasma d-tubocurarine concentration after 7 days of infusion was 26.0 +/- 12 ng/ml (mean +/- SE). Regardless of burn or sham injury or of d-tubocurarine or saline infusion, the concentration of AChRs on the left was consistently greater than in the contralateral right gastrocnemius muscles within the same group, indicating that manipulation of the area alone can result in upregulation of AChRs. The AChRs in the right gastrocnemius of burn-injured animals were greater than those in the same muscle of sham-injured animals, regardless of saline (7.24 +/- 0.9 vs. 5.7 +/- 0.5 fmoles/mg protein, P = 0.06) or d-tubocurarine (7.3 +/- 0.4 vs. 5.7 +/- 0.5, P < 0.05) infusion to the burn-injury groups. AChRs in the left gastrocnemius of burn-injury animals receiving d-tubocurarine were significantly greater than those in burn- or sham-injury animals receiving saline (13.9 +/- 1.1 vs. 9.8 +/- 1.2 and 7.1 +/- 0.5 fmoles/mg protein, respectively, P < 0.05). CONCLUSIONS: Burn-induced upregulation of AChRs is accentuated by infusion of subparalytic doses of d-tubocurarine. Concomitant administration of d-tubocurarine to burn-injured patients may result in further exaggeration of the aberrant responses to neuromuscular relaxants. 相似文献
95.
Mueser Kim T.; Bellack Alan S.; Wade Julie H.; Sayers Steven L.; Tierney Ann; Haas Gretchen 《Canadian Metallurgical Quarterly》1993,102(3):339
Examined social skills and social perception of 48 schizophrenia/schizoaffective disorder patients (aged 18–55 yrs) in response to negative affect as a function of family expressed emotion (EE). Ss participated in a role-play test, a social perception test, and a problem-solving discussion with a family member and were assessed on several measures of symptomatology. EE of family members was evaluated with the Camberwell Family Interview. On the role-play test, Ss with less critical relatives became more assertive in response to increased negative affect from a confederate portraying either a family member or friend, but Ss with highly critical relatives did not. Ss with highly critical relatives were also less assertive when confronted with negative affect from a confederate portraying a family member rather than a friend. The behaviors of both relatives and Ss during a family problem-solving interaction were related to the EE dimensions of criticism, emotional overinvolvement, and warmth. Patient gender was also related to family problem solving but was independent of EE. S's ratings of affect on a videotaped social perception task were not related to family EE, and there were few differences in psychopathology between Ss with high and low EE relatives.… (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
96.
Keizo Uematsu Masayori Miyashita Jin-Young Kim Zenji Kato Nozomu Uchida 《Journal of the American Ceramic Society》1991,74(9):2170-2174
Green bodies prepared by compaction of alumina granules were made transparent by an immersion liquid technique, and the internal structure was characterized with an optical microscope to study the effect of forming pressure on the internal structure. Clear images obtained by the technique provide more detailed information than other existing methods for structures ranging from one to tens of micrometers. Intergranular pores were present between unfractured granules. Their sizes and concentration tended to decrease with increasing forming pressure. However, pores were clearly present even in the green body prepared at 600 MPa. A rod- and needlelike feature was also found and was concluded to correspond to a high-density region. The significance of large pores and high-density regions on processing as well as the details of the technique is discussed. 相似文献
97.
98.
Kinicki Angelo J.; Hom Peter W.; Trost Melanie R.; Wade Kim J. 《Canadian Metallurgical Quarterly》1995,80(3):354
Two studies examined whether the accessibility of performance prototypes influences performance appraisals. Pilot studies revealed students used performance prototypes when rating instructor performance. Study 1 manipulated the accessibility of these prototypes and the time delay of performance ratings. Results showed no effect of the prime on rating error and accuracy; however, discrimination accuracy decreased over time and recognition bias became more conservative. Study 2 manipulated prototype accessibility and type of rating stimuli (videotape vs. vignette). Rating accuracy and recall were higher for vignette than videotape stimuli, and only those participants exposed to the vignette exhibited priming effects. Results supported transfer-appropriate processing and implied that cognitive primes may have a stronger effect on performance ratings based on "paper-people" than videotaped stimuli. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
99.
Phase-change read-and-write memory (PRAM) is a promising memory that can solve the problems of conventional memory—scalability, read/write speed, and reliability. We will review the opportunities and technical challenges of PRAM. The most important challenge of PRAM is the reduction of the writing current. Various approaches to reduce the writing current will be reviewed and the prospects of PRAM are discussed. 相似文献
100.
YoungJu Choie Dougherty S.T. Haesuk Kim 《IEEE transactions on information theory / Professional Technical Group on Information Theory》2003,49(5):1275-1282
We define the complete joint weight enumerator in genus g for codes over /spl Zopf//sub 2k/ and use it to study self-dual codes and their shadows. These weight enumerators are related to the theta series of the associated lattices and Siegel and Jacobi forms are formed from these series. 相似文献