High-frequency analysis of the Ellipticus antenna

Efficient numerical solution techniques have been developed and used to examine the electromagnetic fields that can be developed in the working volume of the CW Ellipticus antenna operated at frequencies from 100 kHz to 1 GHz. An exponentially tapered transition section is designed to obtain the desired illumination pattern in the working volume. The input transition section is needed for impedance matching and to drive efficiently the Ellipticus antenna. A parametric study is performed to ascertain the performance of the Ellipticus antenna for frequencies up to 1 GHz     

Epidemiological study of hypertension and its determinants in an urban population of North India

OBJECTIVES: To determine age-specific prevalence of hypertension and blood pressure (BP) levels in relation to diet and lifestyle factors in North Indians. DESIGN AND SETTING: Cross-sectional survey in 20 randomly selected streets in Moradabad, North India. SUBJECTS AND METHODS: A total of 1806 subjects from North India (904 males and 902 females) age range 25-64 years. The survey methods were as follows: dietary diaries for 7 days food intake record; BP measurements; physician administered questionnaire and anthropometric measurements. Diagnosis of hypertension was based on new World Health Organization/International Society of Hypertension (WHO/ISH) criteria. Risk factors were assessed based on WHO guidelines. RESULTS: The prevalence of hypertension according to WHO/ISH criteria was 23.7% and by old WHO criteria 13.3%. In the WHO/ISH hypertensive group, isolated diastolic hypertension was present in 47.3% males and 40.6% females. Males have a slightly higher prevalence than females in the young age group, however, the prevalence rates are comparable in the older age groups. In both sexes, the prevalence rates and BP level increased with older age. Multivariate analysis revealed that age, higher body mass index, central obesity and higher socioeconomic status were independently and strongly associated with hypertension in both sexes. Higher dietary fat and salt intake and lower physical activity were weakly but significantly associated with hypertension. CONCLUSION: Association of higher socioeconmic status, higher body mass index and central obesity in North Indian adults with higher fat intake, lower physical activity and higher prevalence and level of hypertension indicate that these populations may benefit by decreasing the dietary fat intake and increasing physical activity, with an aim to decrease central obesity for decreasing hypertension in North Indians.     

Protein analysis of human von Ebner saliva and a method for its collection from the foliate papillae

The lingual serous glands of von Ebner are located close to the foliate and circumvallate papillae. Saliva secreted by these glands provides the immediate environment of the taste buds, and it has been hypothesized that it modulates taste perception. The purpose of this study was to develop a technique for collection of unstimulated and stimulated saliva from human von Ebner glands. Saliva was collected under resting conditions and after application of various gustatory stimuli (sweet, sour, salt, and bitter) by insertion of periostrips into the folds of the foliate papillae of healthy human volunteers. Stimulated saliva was also collected in glass microcapillaries or micropipettes. The flow-rates of unstimulated von Ebner saliva were 2.3 +/- 0.6 (S.E.) microL/min and 4.5 +/- 1.2 (S.E.) microL/min with 1% citric acid stimulation. The protein content was 2.5 +/- 0.5 (S.E.) mg/mL. The SDS gel electrophoretic profile of von Ebner saliva revealed two protein bands of Mr 18,000 that were identified on Western blots as von Ebner gland (VEG) proteins. Although lingual lipase activity was detected at very low levels by enzyme assay, this protein was not detected on Western blots. This collection technique should prove useful for analysis of specific functions associated with secretion from von Ebner glands.     

Langmuir-Blodgett deposited cadmium gate inverted InP-GaInAs modulation-doped field-effect transistors

We report on the Langmuir-Blodgett film deposition and plasma etching of cadmium distearate on n-Gao.47Ino.53As to form a high-barrier-height Schottky barrier. Using this technique to form the gate electrode, we fabricated a 1?m-gate-length inverted InP-GalnAs modulation-doped field-effect transistor (MODFET) with an extrinsic transconductance of 170mS/mm and a cutoff frequencyfT of 19 GHz.     

P300 latency: abnormal in sleep apnea with somnolence and idiopathic hypersomnia, but normal in narcolepsy

To evaluate cognitive abnormalities in excessive daytime sleepiness (EDS) using cognitive evoked potentials (P300), and to evaluate if P300 measures differentiate among disorders of EDS, a series of EDS subjects were administered a polysomnogram, auditory and visual P300 testing using 31 scalp electrodes, and a multiple sleep latency test. P300 variables were compared with those of normal subjects. Forty normal subjects ages 16 to 65 years, and 69 EDS patients ages 16 to 65 years were used. Of these, 39 had profound obstructive sleep apnea (OSA, Respiratory Disturbance Index or RDI > 80/h sleep) with severe somnolence (Mean Sleep Latency < 5 min). Twenty-two had idiopathic hypersomnia (IH). Eight had narcolepsy. The normals and the three EDS groups did not differ in age. IH and profound OSA patients had longer visual P300 latency than normals or narcolepsy patients (p < 0.05). (p < 0.05). IH and profound OSA patients had longer auditory P300 latency than normals. They had smaller auditory P300 amplitude than narcolepsy patients. There were visual P300 latency topographic differences between normals and profound OSA patients. In conclusion, IH and profound OSA patients show cognitive evoked potential evidence of cognitive dysfunction. Narcolepsy patients do not show such evidence. Visual P300 latency differentiates among disorders of EDS.     

The effects of lead exposure on learning in a multiple repeated acquisition and performance schedule

This study sought to determine the selectivity of Pb-induced changes in learning, as distinct from non-specific or performance effects, and to explore the nature of the underlying error patterns contributing to any learning deficits. To accomplish this, rats were chronically exposed to 0, 50, or 250 ppm Pb acetate in drinking water from weaning and trained on a multiple repeated acquisition (RA) and performance (P) schedule beginning at 55 days of age. The RA component required the rat to learn a new 3-member sequence of responses during each experimental session (Center Right Left, RLC, CLR, RCL, and LRC), while the correct sequence of responses for the P component was constant across sessions (LCR). Significant decrements in accuracy on the RA component but not on the P component were found in Pb-exposed groups compared to control, effects that could not be attributed to differential rates of responding. Analyses of error patterns revealed that the effects of Pb exposure on RA accuracy levels derived from two sources. The first consisted of a perseveration of P-like sequence responding (LCR) even during the RA component. Secondly, Pb exposure increased perseverative responding on a single lever, even though the schedule itself never directly reinforced such repetitive responding. The increase in frequency of these two types of perseverative behavior was incompatible with acquisition of non P-like sequences during the RA component. Adding a 5 sec tone to the light stimuli signalling the transition between RA and P components of the multiple schedule failed to attenuate these effects of Pb, suggesting that deficits in stimulus control were not the sole behavioral mechanism of these impairments. Examination of individual data revealed the presence of both 'learners' and 'non-learners' in each group, with the prevalence of the latter being suggestively higher in Pb-exposed groups than in controls. These findings may be relevant to the classroom setting, where periods requiring learning may frequently be interspersed with periods of performance of learned skills.     

Quantitative evaluation of pancreatic enhancement during dual-phase helical CT

PURPOSE: To determine the improvement in pancreatic enhancement at helical computed tomography (CT) performed with an early delay after administration of contrast material compared with that performed with a standard delay. MATERIALS AND METHODS: Dual-phase helical CT of the abdomen was performed in 120 patients with a 150-mL bolus of contrast material infused at 5 mL/sec. Early and standard delayed scanning was performed beginning at 20 seconds and 49-71 seconds, respectively. Regions of interest were measured in the head, body, and tail of the pancreas in 92 patients. The difference in enhancement between early and standard delayed scanning was calculated. RESULTS: Mean pancreatic enhancement was 82 HU +/- 3 (standard error) with an early delay, whereas enhancement on standard delay scans was 62 HU +/- 2 (P < .001). An improvement in enhancement greater than 10 HU was attained in 66 of 92 cases (72%). CONCLUSION: Pancreatic enhancement at helical CT with an early delay after contrast material administration is often significantly greater than the enhancement seen with a standard delay when a monophasic, rapidly infused bolus of contrast material is used.     

Motion of a solid sphere in a general flow near a plane boundary at zero Reynolds number

It is demonstrated how the hydrodynamic force and moment of force acting on a solid sphere may be calculated when it is placed at rest at an arbitrary position in a two dimensional flow at zero Reynolds number in which the region of flow is bounded by either an undeformable planar free surface or by a plane solid wall. The results so obtained are used to calculate the motion of a freely moving solid sphere in an asymmetric vortex in the presence of an underformable free surface. It is seen that the sphere, depending on the direction of the undisturbed flow, will either spiral into or out of the vortex. This implies that when a dilute suspension of such spherical particles undergoes such a vortex motion in the presence of the free surface, the vortex will either fill up with particles from the surrounding flow or become devoid of particles.Deceased, July 31, 1995     

The domain composition method applied to Poisson's equation in two dimensions

Domain composition, a recently described method for formulating continuum field problems, removes certain restrictions on the construction of finite element models such that it is possible to solve a finite element problem without using a global compatible mesh. The domain composition method couples or otherwise constrains meshes in local regions to obtain a solution equivalent to that produced by conventional finite element methods. In particular, the domain composition method enables finite element models to be formulated with overlapping elements. Several advantages come from this, including an ability to automatically generate a finite element model from a solid geometric model, an ability to use a variety of element types in a single finite element model and an ability to exactly match element boundaries to the local geometry. This paper shows in detail a finite element formulation of Poisson's equation using domain composition and presents certain key algorithms that incorporate the domain composition method into well-established finite element procedures.