Mean Wave Amplitude Research Articles

Effect of early onset otitis media on brainstem and cortical auditory processing

BackgroundOtitis media (OM) leads to significant reduction in the hearing sensitivity. The reduced auditory input, if in the early years of life when the auditory neural system is still maturing, may adversely influence the structural as well as functional development of the system. Past research has reported abnormalities in both the structure and function of brainstem nuclei following auditory deprivation, but, it has not necessarily focused on children who had OM in their first year of life. It can also be said that if auditory processing is affected at the brainstem level because of early onset OM (reduced auditory input in the crucial periods of neural development), then, it may be said that auditory processing is also affected at the cortical level because it receives distorted input from the brainstem. Therefore, the purpose of this study was to document the effects of early onset OM on auditory processing, if any, at the brainstem as well as at cortical levels. A related purpose of the study was to investigate the persistence of the effects of early onset OM, if any, on auditory processing.MethodsA cross sectional approach and a standard group comparison design was used in the study. Thirty children, who had OM between 6 and 12 months of age and who were in the age range of 3.1 – 5.6 years participated in the study. Children with OM were divided into 3 groups based on their age. Click evoked auditory brainstem responses (ABRs) and late latency responses (LLRs) were recorded from these children, and the responses were compared with those from age and gender matched normal children without any history of OM. The data from the 2 groups was statistically analyzed through independent t test. Pearson's Product Moment correlation was computed to examine the relationship between results of ABR and LLR in children with early onset OM.ResultsThe mean central conduction time was significantly increased and the mean amplitude of wave I and III of ABRs was significantly reduced in children with early onset OM compared to normal children. Also, the latency of all LLR waves was significantly less in children with early onset OM than in normal children. However, significant differences in mean values of either ABR or LLR (latencies or interwave intervals as the case may be) were observed only in 3-year old children. There was a significant, but negative association between central conduction time and latency of LLRs.ConclusionOM in the first year of life leads to negative effects on brainstem signal processing even if it has occurred only for a short duration (maximum of 3 months). In such a situation, auditory cortical structures probably show compensatory changes through central gain to offset the prolonged central conduction time. Although the results of the present study showed that the negative effects of early onset OM (occurring in the first year of life) on auditory processing disappeared by the time the children were 4.1 years, there is need for longitudinal studies on this to confirm the findings.

Intracranial pulse pressure amplitude levels determined during preoperative assessment of subjects with possible idiopathic normal pressure hydrocephalus

It was previously reported that the intracranial pulse pressure amplitudes were elevated in idiopathic normal pressure hydrocephalus (iNPH) patients responding to shunt surgery. In this study, pulse pressure amplitudes were determined in all patients referred for tentative iNPH, and patients were selected for shunt surgery based on the determination of their threshold levels of intracranial pulse pressure amplitudes. All patients referred to our department for tentative iNPH during a 12 months time period were included. Using intracranial pressure (ICP) monitoring the intracranial pulse pressure amplitudes were determined as the mean wave amplitude in consecutive 6-seconds time windows. Intracranial pulse pressure amplitudes were defined as being elevated when the mean wave amplitudes were either >or=4 mmHg in >or=70%, >or=5 mmHg in >or=40% or >or=6 mmHg in >or=10% of the ICP recording time. Shunt treatment was offered to those with elevated mean wave amplitudes. Clinical state was assessed by using a NPH Grading Scale and the Stein-Langfitt scale before ICP monitoring, and then repeated after 12 months. Among the 40 iNPH patients included during the 12 months period, the mean wave amplitudes were elevated in 24 patients (60%), while not being elevated in 16 (40%). Neither pre-operative clinical state, radiological ventricular size nor co-morbidity differed between patient groups with elevated or non-elevated mean wave amplitudes. In the shunted patients who had pre-operatively elevated mean wave amplitudes, 91% had very significant clinical change after 12 months (median change in NPH score +4). In those with non-elevated amplitudes and no shunt, clinical state was somewhat worse after 12 months (median change in NPH score -1). In this one-year material, mean wave amplitudes were elevated in 60% of iNPH patients. In those with elevated mean wave amplitudes who were treated with shunt, 91% had a significant clinical response.

Lumbar cerebrospinal fluid pressure waves versus intracranial pressure waves in idiopathic normal pressure hydrocephalus

The aim of this study was to explore how the lumbar cerebrospinal fluid pressure (CSFP) waves recorded during lumbar infusion compared with the intracranial pressure (ICP) waves recorded, either during lumbar infusion or during long-term, overnight monitoring. For this purpose, we assessed 27 simultaneous lumbar CSFP/ICP recordings made during lumbar infusion and 27 long-term, overnight ICP recordings in 27 consecutive idiopathic normal pressure hydrocephalus (iNPH) patients. Pressure waves during lumbar infusion were explored by computing pulse pressure amplitude and mean single wave pressure of every corresponding CSFP/ICP wave pair; among our 27 lumbar CSFP/ICP recordings a total of 35,532 CSFP/ICP wave pairs were available for analysis. We as well computed mean values of pulse pressure amplitude (i.e. mean CSFP wave amplitude or mean ICP wave amplitude) and mean values of mean single wave pressure (i.e. mean CSFP or mean ICP) during consecutive 6-s time windows, as well as average values for the individual recordings. During lumbar infusion, the cerebrospinal fluid pulse pressure amplitudes were about 2 mmHg smaller than the corresponding intracranial pulse pressure amplitudes. The mean CSFP wave amplitudes recorded during lumbar infusion correlated significantly with the mean ICP wave amplitudes recorded either during lumbar infusion or during long-term, overnight ICP monitoring. In 21 of 27 lumbar infusion tests (78%), the presence of elevated lumbar mean CSFP waves was related to presence of elevated mean ICP wave amplitudes during long-term, overnight ICP monitoring. Hence, the lumbar cerebrospinal fluid pulse pressure amplitudes recorded during lumbar infusion could be used to predict the intracranial pulse pressure amplitudes recorded during long-term, overnight ICP monitoring.

A new method for processing of continuous intracranial pressure signals

This paper describes a new method for processing of continuous pressure signals. Continuous intracranial pressure (ICP) signals were sampled at 100 Hz, converted into digital data and processed during 6 s time windows. According to a new algorithm, cardiac beat-induced single ICP waves were identified; pressure waves caused by noise in the signal were rejected for further analysis. The amplitude and latency values of the accepted single ICP waves were determined. For accepted 6 s time windows, the mean ICP wave was computed as mean ICP wave amplitude and mean ICP wave latency. Mean ICP for every time window was computed according to current practice as sum of pressure levels divided by number of samples. The mean ICP wave parameters provide information about the single ICP waves that is not given by mean ICP. The method has been implemented in software to be used during online ICP monitoring, revealing mean ICP wave amplitude, mean ICP wave latency and mean ICP as numerical values every 6 s. The values are presented in trend plots. Verification of correct single ICP wave identification can be done during online ICP monitoring. The clinical significance of the method was illustrated in four patients by observations that mean wave amplitudes corresponded better to the acute clinical state than the mean ICP; mean wave amplitudes could be elevated despite a normal mean ICP. In one patient with ICP and arterial blood pressure (ABP) signals monitored simultaneously with identical time reference, there was a weak correlation between mean ICP and ABP wave amplitudes. It is tentatively suggested that the mean ICP wave parameters are related to intracranial pressure–volume compensatory reserve capacity (compliance).

Comparison of simultaneous continuous intracranial pressure (ICP) signals from a Codman and a Camino ICP sensor

Simultaneous continuous intracranial pressure (ICP) signals from two different sensors were compared. Continuous ICP monitoring from two ICP sensors (i.e. Codman ICP MicroSensor; Johnson & Johnson, Raynham, MA and Camino OLM ICP; Camino Laboratories, San Diego, CA) placed within the brain parenchyma was performed in three patients within the intensive care unit (ICU) as part of routine management of severe subarachnoid hemorrhage. For each 6 s time window mean ICP was computed, showing large differences in mean ICP values between the signals. Differences above 5 mmHg were observed in 13% of the 128,425 time windows derived from 214 h ICP recordings in these three patients. In one patient, mean ICP differed more than 10 mmHg in 23% of the time windows. Comparisons of 675,503 individual single pressure wave pairs of these 128,425 time windows revealed marginal differences in single wave amplitude (d P, i.e. pulse pressure) and latency (d T, i.e. rise time) values, suggesting that differences in mean ICP were caused by differences in baseline pressure. For the individual time windows were computed the mean wave amplitude and mean wave latency values according to a new algorithm. There were as well marginal differences between signals of mean wave amplitude and latency values. Thus, changes in baseline pressure affect mean ICP but not single pressure wave characteristics such as amplitude (d P) and (d T) latency values.

Counter-current gas–liquid flow in a vertical narrow channel—Liquid film characteristics and flooding phenomena

Results are reported of an experimental investigation of gas–liquid counter-current flow in a vertical rectangular channel with 10 mm gap, at rather short distances from liquid entry. Flooding experiments are carried out using air and various liquids (i.e., water, 1.5% and 2.5% aqueous butanol solutions) at liquid Reynolds numbers Re L < 350. Visual observations and fast recordings suggest that the onset of flooding at low Re L (<250) is associated with liquid entrainment from isolated waves, whereas “local bridging” is dominant at the higher Re L examined in this study. Significant reduction of flooding velocities is observed with decreasing interfacial tension, as expected. Instantaneous film thickness measurements show that under conditions approaching flooding, a sharp increase of the mean film thickness, of mean wave amplitude and of the corresponding RMS values takes place. Film thickness power spectra provide evidence that by increasing gas flow the wave structure is significantly affected; e.g., the dominant wave frequency is drastically reduced. These data are complemented by similar statistical information from instantaneous wall shear stress measurements made with an electrochemical technique. Power spectra of film thickness and of shear stress display similarities indicative of the strong effect of waves on wall stress; additional evidence of the drastic changes in the liquid flow field near the wall due to the imposed gas flow, even at conditions below flooding, is provided by the RMS values of the wall stress. A simple model is presented for predicting the mean film thickness and mean wall shear stress under counter-current gas–liquid flow, below critical flooding velocities.

Electrocardiographic and electrophysiological characteristics of atrial fibrillation organized into atrial flutter by oral administration of class I antiarrhythmic agents.

The aim of this study was to evaluate the electrocardiographic (ECG) and electrophysiological characteristics of atrial fibrillation (AF) that organized into atrial flutter during oral administration of class I antiarrhythmic agents. The former clinical study included 72 consecutive patients (58 paroxysmal AF, 14 persistent AF) in whom class I antiarrhythmic agents were orally administered in the outpatient clinic for termination or prophylaxis of AF. The clinical background and ECG variables were compared between the patients with and without atrial flutter during class I antiarrhythmic agents therapy. An electrophysiological study was performed in ten patients with paroxysmal AF (five with [group A] and five without atrial flutter [group B] during oral class I antiarrhythmic agents therapy. Local electrograms from five different atrial sites (high and low right free wall, high and low septum, and distal coronary sinus) were analyzed during induced AF. The activation pattern of the right free wall during AF was also analyzed using a Halo catheter. Atrial flutter was documented during class I antiarrhythmic agents therapy in 14 (24%) patients with paroxysmal AF, whereas in none with persistent AF. The mean cycle length (f-f interval) and amplitude of the fibrillation waves in leads II and V1 from the surface ECG were significantly greater in the patients with than in those without atrial flutter. In the electrophysiological study, the mean cycle lengths for the low and high right free wall were significantly longer in group A than in group B, whereas those for the low septums and distal coronary sinus did not differ between the two groups. During the induced AF, the ratio of time exhibiting a consistent activation pattern (cranio-caudal, caudo-cranial, or undetermined) along the right free wall was significantly greater in group A than in group B. Atrial flutter newly developed during class I antiarrhythmic agents therapy in patients with coarse AF on the surface ECG and a relatively organized activation in the right atrial free wall. The observation of these findings may facilitate the identification of candidates for hybrid pharmacologic and ablative therapies.

Simulation of the submerged energy nozzle-mold water model system using laser-optical and computational fluid dynamics methods

The present work describes quantitative digital particle image velocimetry measurements of a full-scale water model of a thin slab mold. Different casting speeds and two submerged entry nozzles with one and two outlet ports have been investigated. The flow pattern of the single-port nozzle shows a counterclockwise-rotating double vortex that is nearly steady-state but leads to high stationary surface waves. The flow jets out of the two-port nozzle oscillate and produce a transient flow pattern with low wave amplitudes. The amplitudes for the one-port nozzle show a linear variation with the volumetric flow rate. The experimental results lead to a good interpretation of the flow phenomena and are used to validate steady-state numerical simulations with the commercial program, CFX, on the basis of the Reynolds equations. To describe anisotropic turbulence effects, the Reynolds stress model (RSM) is used for the flat single-port nozzle and the standard k-ɛ model for the mold flow. The calculated mean velocities and wave amplitudes, predicted from pressure distribution at the water surface, are generally in the consensus of the experimental data.

Effects of interfacial shear stress on laminar-wavy film flow

In the present study the behavior of laminar-wavy film flowing down a vertical plate was studied analytically. The effects of film Reynolds number and interfacial shear stress on the mean film thickness, wave amplitude, wave length, and wave celerity were analysed. The anayltical results on the periodic-wave falling film showed good agreements with experimental data for Re

Effects of channel cross-sectional geometry on long wave generation and propagation

Joint theoretical and experimental studies are carried out to investigate the effects of channel cross-sectional geometry on long wave generation and propagation in uniform shallow water channels. The existing channel Boussinesq and channel KdV equations are extended in the present study to include the effects of channel sidewall slope at the waterline in the first-order section-mean equations. Our theoretical results show that both the channel cross-sectional geometry below the unperturbed water surface (characterized by a shape factor κ) and the channel sidewall slope at the waterline (represented by a slope factor γ) affect the wavelength (λ) and time period (Ts) of waves generated under resonant external forcing. A quantitative relationship between λ, Ts, κ, and γ is given by our theory which predicts that, under the condition of equal mean water depth and equal mean wave amplitude, λ and Ts increase with increasing κ and γ. To verify the theoretical results, experiments are conducted in two channels of different geometries, namely a rectangular channel with κ≡1, γ=0 and a trapezoidal channel with κ=1.27, γ=0.16, to measure the wavelength of free traveling solitary waves and the time period of wave generation by a towed vertical hydrofoil moving with critical speed. The experimental results are found to be in broad agreement with the theoretical predictions.

Viscoacoustic wave propagation in 2-D random media and separation of absorption and scattering attenuation

Wave theoretical analysis of scalar, time‐harmonic waves propagating in a constant density medium with isotropic, random velocity fluctuations and being scattered mainly in the forward direction yields a simple and robust procedure that combines the logarithm of the mean wave amplitude with the mean logarithm of the wave amplitude to perform a separation of scattering attenuation and absorption effects. Finite‐difference simulations of wave propagation in 2-D random media with a Voigt‐body rheology illustrate the evolution of wave field fluctuations and demonstrate that the separation procedure works for a wide range of seismic albedos. In the case of no absorption, the logarithms of seismic amplitudes will have a nonlinear dependence on the travel distance if the wavefield fluctuations are small compared to the amplitude of the coherent field. If these fluctuations are large, the logarithms of seismic amplitudes will tend to constant levels independent of the travel distance. In the case of random viscoacoustic media and at propagation distances larger than the inverse of the scattering coefficient of the coherent field, and apart from geometrical spreading, the overall amplitude decrease will be predominated by absorption, even if the absorption coefficient is one order smaller than the scattering coefficient of the coherent field.

Auditory brain stem evoked responses (ABRS) in children with delayed speech (DS) a diagnostic problem

The results of analysis of auditory brain- stem evoked responses (ABRS) are reported in 173 patients with delayed speech (DS). The mean age of the patients is 4.6 years (age ranges from 1.4 years to 10 years). The patients were classified into 5 groups based on ABR findings: Group I (62 patients) had normal hearing threshold and peak- interpeak latencies. The mean amplitude of wave I was however, not significantly low (p < 0.03). Group II (27 patients) had an increased hearing threshold (40 dB), mild delay in the mean absolute peak latency of wave I (p < 0.03), decreased I– IV interval (p < 0.03), but highly significant reduction of wave I amplitude (p < 0.004). There is also a significant latency delay (p < 0.001) and amplitude reduction (p < 0.05), when this wave is compared with that a Group I (as control). These observations are suggestive of mild degree of peripheral hearing deficit in this group. Group III (49 patients) had gross ABR abnormalities of various nature and hence may be sub- grouped into (a) SNHL cochlear type (55%) (b) SNHL retrocochlear type (4%) and (c) severed degree of SNHL undecisive group (41%). Ten patients (2.7%) among the sub- group (a) had unilateral hearing loss and another 3 had Down’s syndrome. Group IV (conductive deafness) had an increased hearing threshold and shifting of ABR waves towards right with normal I– V interval. Only 6 patients were found in this group. It may be that conductive deafness is less important as a cause. Group V (29 patients) had no responses at repeated ABR studies even at higher intensity of 95 dB, the ABR studies of this group correlates with the clinical evaluation of profound deafness. The delayed speech development in 84 patients (from Groups III, IV and V) may be caused by severe degree of hearing deficit as indicated by marked ABR abnormalities. If the mild peripheral hearing loss in Group II is added to the above groups, ABRs could identify 64.6% of our patients with hearing deficit. Hence, ABR test is most reliable and sensitive diagnostic test in detecting hearing loss, a common cause of delayed speech development in children.

Ray‐tracing simulation of the global propagation of inertia gravity waves through the zonally averaged middle atmosphere

The global propagation of large‐horizontal‐wavelength inertia gravity waves through a zonally averaged geostrophic wind and temperature climatology of the middle atmosphere is investigated using numerical ray‐tracing techniques. Strong meridional shear in the zonal wind acts to refract waves horizontally (azimuthally), leading to changes in the local propagation azimuth, horizontal wavelength, and ground‐based horizontal phase speed of the wave. Unlike other identified mechanisms which can produce such changes, this refraction effect is linear and does not require (nor forbid) that the wave amplitude be unstable for it to occur. Careful treatment of wave amplitudes indicates that such refracted waves are suppressed in amplitude far less by radiative damping and saturation than previous modeling has suggested, due to the use of a more accurate radiative damping parameterization. Refraction therefore is potentially important in modifying the waves' characteristics as they propagate through the middle atmosphere, and simulations reveal modifications which agree broadly with some observational data. Multiray simulations, using a horizontally isotropic source “spectrum” of waves with equal initial amplitudes, produce wave amplitudes at a height of 60 km which exhibit variations with latitude, season, and vertical wavenumber which have much in common with observations. A dearth of waves with large horizontal wavelengths also arises, in agreement with collated observations in the upper middle atmosphere. Significant differences in the latitude‐season structure of the mean wave amplitudes of the northern and southern hemisphere are simulated. The simulations reproduce the well‐known change in mean azimuthal wave propagation from eastward in summer to westward in winter, but the simulated westward phase invariably exceeds 6 months in duration, and in places the eastward summer phase is very weak and of limited duration. In addition, a smaller but nonetheless distinct poleward component to the mean propagation directions arises, due in part to horizontal refraction. Comparison of measured and simulated distributions of wave propagation azimuths reveals good agreement at some locations. Mid‐latitude winter distributions around North America are well simulated when only c = 0 waves are retained. However, significant differences also occur, which may reflect the importance of features omitted from this model, such as zonal atmospheric variability and/or wave source effects. These and other limitations of the present model are highlighted; it is recommended that subsequent simulations incorporate zonal refraction due to planetary Rossby wave structure, and that higher‐frequency waves be included so that the impact of refraction on the vertical flux of horizontal wave momentum can be assessed.

Reevaluation of manometric criteria for vigorous achalasia

Clinical and manometric data from 97 consecutive patients with idiopathic achalasia were analyzed to see if a distinct subset with vigorous achalasia could be identified. Statistical analyses failed to detect a unique group of subjects based on the distribution of contraction wave amplitudes alone. Because of this, patients falling above the 95th percentile (N = 4, mean wave amplitude greater than 100 mm Hg for each) were compared with those having mean amplitudes above the conventional threshold for the diagnosis of vigorous achalasia (mean amplitude 60-100 mm Hg, N = 4), and with the remainder (N = 89, mean amplitude less than 60 mm Hg). Subjects with mean amplitudes less than 60 mm Hg and with mean amplitudes 60-100 mm Hg closely resembled each other in all measured clinical features, whereas subjects with mean amplitudes greater than 100 mm Hg were all male, were older (67 +/- 4 years vs 47 +/- 2 years; P less than 0.01), and appeared to have somewhat longer duration of symptoms when compared with the remainder (82 +/- 41 vs 44 +/- 10 months; P = 0.4). Chest pain and other esophageal symptoms, basal and residual lower sphincter pressures, and response to first treatment did not differ among the three groups. These data indicate that high-fidelity manometry techniques identify a rare subset of achalasia patients with mean contraction amplitudes exceeding 100 mm Hg that, although older and possibly with greater duration of symptoms, presents similarly to others with idiopathic achalasia. Outcome from conventional treatment is also similar for the "vigorous" and "nonvigorous" patients, making the distinction of questionable value.

Electrocardiographic left ventricular hypertrophy and effects of antihypertensive drug therapy in hypertensive participants in the multiple risk factor intervention trial

Data are reported on electrocardiographic left ventricular hypertrophy (ECG LVH) among 8,012 men classified as hypertensive at baseline in the Multiple Risk Factor Intervention Trial. Compared with those allocated to the usual care (UC) control group, men allocated to the special intervention (SI) group experienced a mean reduction of 4 mm Hg in diastolic blood pressure and 7 mm Hg in systolic blood pressure, over 6 years of follow-up. There were 378 new cases of ECG LVH during follow-up; the incidence in the SI group was about 23% less than that in the UC group (4.2 vs 5.4% 2P < 0.01). Among the 189 men with ECG LVH at baseline, those in the SI group experienced about 24% more annual follow-up visits at which they were free of ECG LVH (4.6 vs 3.7 visits; 2P < 0.01). This reduced incidence and increased reversal of ECG LVH in the SI group compared with that in the UC group was consistent with significant overall reductions (2P < 0.001) among SI men in mean wave amplitude in those leads in which voltage is correlated with left ventricular mass (T wave in V 1, R wave in aVL and S wave in V 3). In SI and UC groups combined, the presence of ECG LVH either at baseline or at follow-up was associated with several-fold increases in death from cardiovascular diseases in general, and death from coronary artery disease in particular. While mortality from cardiovascular disease, including coronary artery disease, was not significantly different in SI and UC groups during follow-up, moderate though still potentially worthwhile benefits that might accompany the observed ECG changes cannot be excluded.

Surface wave propagation in a random layered medium

The author considers the propagation of surface Love waves in a random layered elastic medium. The material parameters in the model are stochastic functions of the vertical coordinates chi 3: this includes the general case when the wave propagates through a statistically inhomogeneous layer. The author applies the averaging method for stochastic equations. The method essentially involves approximating the expectation of the solution with averages formed by integrating various moments of the random coefficients over 'long' times (long relative to the correlation time). This method provides higher-order corrections to the purely asymptotic approximations which are often used to solve equations of this type. It is shown that the mean wave amplitude always attenuates exponentially on the depth scale in 2 chi 3 where in is the fluctuation parameter. The author analyses the dispersion relation for a statistically homogeneous layer and finds a criterion which determines whether the mean phase velocity is decreased by the fluctuations.

The effects of a supratentorial mass lesion on brain-stem auditory evoked potentials and short latency somatosensory evoked potentials.

Nineteen patients with unilateral supratentorial mass lesion and without any evident clinical signs of transtentorial herniation were studied with Computed Tomography (CT), brain-stem evoked potentials (BAEPs) and central conduction time (CCT) of short latency somatosensory evoked potentials (SEPs). Sixteen had tumours, two had intracranial haematoma and one had chronic subdural haematoma. CT detected the initial signs of transtentorial herniation in every case. Preoperative I-V interpeak latency (IPL) was significantly (M + 2SD) prolonged in 26% of cases on the lesion side and in 21% of cases on the opposite side. The mean I-V IPL was significantly prolonged both on the lesion side and the opposite side (P less than 0.01, P less than 0.02, respectively). Suppression of Wave V (M-2SD) was seen only in two cases, however, the mean amplitude of Wave V was significantly decreased both on the lesion side and on the opposite side (P less than 0.001, P less than 0.01, respectively). CCT of SEPs was significantly (M + 2SD) prolonged in 33% of cases on the lesion side and in only 13% on the opposite side. The mean CCT was, however, significantly prolonged both on the lesion and on the opposite side (P less than 0.001, P less than 0.02, respectively). Postoperative I-V IPL was significantly prolonged in only 11% of cases while the mean I-V IPL was still significantly prolonged (P less than 0.01) and the mean amplitude of Wave V was still suppressed (P less than 0.001) on the lesion side.(ABSTRACT TRUNCATED AT 250 WORDS)

Psychiatric illness and contraction abnormalities of the esophagus.

Over a six-month period 50 patients referred for clinical esophageal manometry were independently evaluated for psychiatric diagnoses to determine whether there was any association between psychiatric illness and esophageal motility disorders. The manometric studies were blindly classified according to findings in the esophageal body. Twenty-five patients were classified as having one or more of the following contraction abnormalities: an increase in mean wave amplitude, an increase in mean wave duration, an increased frequency of abnormal motor responses, or the presence of triple-peaked waves. Psychiatric diagnoses were made in 21 (84 per cent) of the 25 patients but in only 4 (31 per cent) of the 13 patients with normal manometric patterns (P less than 0.005) and 4 (33 per cent) of the 12 with other manometric abnormalities (P less than 0.01). The fact that psychiatric illness is associated with a specific cluster of esophageal contraction abnormalities may provide a basis for further investigation of the relation between emotional disturbances and disorders of gastrointestinal motility.

Short-Period Atmospheric Gravity Waves: A Study of Their Statistical Properties and Source Mechanisms

Gravity waves for the one year period beginning 19 October 1976 around Palisades, New York, are investigated to determine their statistical properties and sources. The waves have typical periods of 10 min, pressure amplitudes of 3 Pa and velocities of 30 m s−1. In general, the largest, amplitude waves occur during late fall and early winter when the upper tropospheric winds directly overhead are fastest and the static stability of the lower troposphere is greatest. Mean wave amplitudes correlate highly with the product of the mean maximum wind speed and the mean low level stratification directly aloft. A distinct diurnal variation of wave amplitudes with the largest waves occurring in the pro-dawn hours is also observed as a result of the increased static stability then. The majority of waves are generated by shear instability; however, a number of waves are generated by distant sources such as nuclear detonations or large thunderstorms. The waves with distant sources can be distinguished on the basis of their generally much higher coherency across the grid and velocities that depart markedly from the wind velocity at any point in the sounding.

The Role of Forced Planetary Waves in the Annual Cycle of the Zonal Mean Circulation of the Middle Atmosphere

The annual cycle of the zonally averaged circulation in the middle atmosphere (16–96 km) is simulated using; a severely truncated semi-spectral numerical model. The model includes only a single zonal harmonic wave component which interacts with the mean flow. The circulation is driven by diabatic heating and by a specified perturbation in the topography of the lower boundary, which is taken to be the 100 mb surface. Damping is included as Newtonian cooling and Rayleigh friction. A comparison of the annual cycle simulated by this model with the results of an analogous two-dimensional model indicates that planetary waves have relatively little influence on the zonal mean temperature profiles and on the solstice mean zonal winds at high latitudes. The primary effects of the forced waves are in decelerating the mean winds in low latitudes in the winter hemisphere to produce a region of weak westerlies, and in generating “final warmings” at the spring equinoxes. Computed mean zonal winds and wave amplitudes display significant hemispheric asymmetries. These differences are associated with the strong dependence of the eddy structure on the mean zonal wind profile. The “residual” mean meridional circulation, computed by subtracting the portion of the Eulerian mean meridional flow which is exactly balanced by the eddy heat fluxes, is nearly identical at the solstices to the Eulerian mean circulation computed in the two-dimensional model. Except in low latitudes, the net mean flow forcing by the eddy fluxes is quite small at the solstices in agreement with the predictions of wave-mean flow non-acceleration theorems. There are no major midwinter sudden warmings produced in the model. However, final warmings occur in the spring equinoctial seasons in both hemispheres. The rapid transient adjustments which occur during these final warmings make the equinoctial circulations in this model much different from the circulations computed for corresponding seasons in the two-dimensional model.