Pressure Trough Research Articles

Effect of periodic wide atmospheric pressure change on CO emission in closed goaf

Atmospheric pressure fluctuation is one of the most important factors affecting the climate environment and gas emission in the fire area. To obtain the influence rule of the surface atmospheric pressure change on the gas sampling and abnormal emission in the mine closed goaf, the No. 1 coal mine in Dananhu was taken as the research object. Using Fourier transform and Fisher harmonic analysis and other statistical methods, the influence of the periodic variation of atmospheric pressure on the gas leakage and outflow in the closed goaf was studied. The results showed that there were three atmospheric pressure periods of 15.2 d, 1 d and 182.2 d, and the probability was greater than 95%. The time period with the highest number of atmospheric pressure peaks was 7:00–8:00, which accounted for 20.2% of total occurrence number in a day. And the time periods with the highest number of atmospheric pressure trough were 2:00, 15:00 and 16:00, accounting for 27.4%. The peak-to-trough transition time was mainly concentrated around 6 h, and the diurnal variation curve of atmospheric pressure was mainly bimodal. The atmospheric pressure change rate was mostly concentrated in 10–50 Pa/h. It was determined that the distance that the gas sampling pipe was pre-laid into the inner side of the closed wall should be greater than 44.4 m, and the CO concentration and atmospheric pressure in the closed goaf were both periodic and negative with atmospheric pressure. The research results have important guiding significance for the monitoring, early warning and environmental protection of the goaf.

Relationship between extensive and persistent extreme cold events in China and stratospheric circulation anomalies

This study examines the relationship between the extensive and persistent extreme cold events (EPECEs) in China and geopotential height anomalies in the stratosphere using daily mean fields of outgoing long wave radiation (OLR) produced by the NCAR and daily atmospheric circulations produced by the NCEP/NCAR. The OLR composite analysis for the EPECE in China demonstrates that the negative OLR height anomalies (cold air) originated from Siberia influence China progressively from north to south. The largest negative OLR height anomaly (cooling event) occurs in the region to the north of the Nanling Mountains. This suggests that the OLR height anomalies can be used to represent the temporal and spatial characteristics of extreme low temperatures and cold air activities in winter in China. The composite analysis of large-scale atmospheric circulations during the EPECE reveals characteristic evolutions of stratospheric and tropospheric circulations during the extreme cold event. We demonstrate the important role of atmospheric circulation anomalies in the outbreak and dissipation of the EPECE in China. We also demonstrate that significant perturbations in the stratospheric circulation occur more than 10 days prior to the outbreak of the EPECE, with positive height anomalies in the Arctic stratosphere. These positive anomalies propagate downward from the stratosphere and affect the formation and development of the high pressure ridge in the middle troposphere over the Ural Mountains. Significant changes also occur in the atmospheric circulation in the mid-latitude stratosphere. These changes propagate downward from the stratosphere and strengthen the low pressure trough in the troposphere in the region to the east of Lake Balkhash and Lake Baikal. Therefore, the changes in the stratospheric circulation during the EPECE in China occur prior to changes in the tropospheric circulation and are very useful for predicting extreme wintertime cold temperatures in China.

Morning Blood Pressure Surge and Glaucomatous Visual Field Progression in Normal-Tension Glaucoma Patients With Systemic Hypertension

To investigate the impact of a morning blood pressure surge (MBPS) at baseline on subsequent visual field (VF) progression in hypertensive, normal-tension glaucoma (NTG) patients receiving oral anti-hypertensive treatment. Retrospective cohort study. A total of 127 eyes from 127 newly diagnosed NTG patients treated for systemic hypertension and followed up for at least 2 years were analyzed. All patients underwent baseline 24-hour ambulatory blood pressure monitoring (ABPM) and at least 5 serial VF examinations during the follow-up period. VF progression was defined according to the Early Manifest Glaucoma Trial criteria. The associations of VF progression with 24-hour ABPM-based blood pressure (BP) parameters (including MBPS) and other clinical variables were analyzed using Cox regression analyses. Kaplan-Meier survival analysis was used to compare VF survival estimates in patients with and without MBPS. VF progression was detected in 38 eyes (29.9%) over a 5.2-year mean follow-up. In the multivariate Cox regression model, a greater MBPS (hazard ratio [HR]=1.033; P=.024) and lower nighttime mean arterial pressure (MAP) trough (HR=0.965; P=.031) at baseline were significant independent predictors of subsequent VF progression. The likelihood of VF progression was significantly greater in patients with higher MBPS (P=.021) at baseline according to Kaplan-Meier survival analysis. An increased MBPS at baseline is a significant independent predictor of subsequent VF progression in NTG patients with systemic hypertension. This may be another relevant BP parameter associated with VF progression in hypertensive NTG patients receiving oral anti-hypertensive treatment.

Assessing the impact of hyperviscosity on stenosis shape in COVID patients

Recent studies have proven that the shape of the stenosis greatly affects the flow characteristics. The 2D rigid wall model examined in this research is analyzed mathematically using various principles and results of functional analysis for the existence and uniqueness of the solution. The model taken into consideration for the current study has also been used to examine the consequences of hyperviscosity in COVID-19 cases. The results of the investigation surmise that the maximum peak velocity of 3.155m/s and the minimum trough pressure of 7041.538Pa were manifested in the high slope geometry. Also, the number of spots over the upper wall of high slope geometry bearing the least wall shear stress was considerably high when compared to the other geometries. The study deduced that the arterial segment bearing dual high slope stenosis was more susceptible to new plaques, plaque ruptures, and hyper viscous syndrome.

Experimental investigation of combustion characteristics analysis and optimization during the turbocharging mode switching process of diesel engine with advanced turbocharging system

Multi-turbocharger system is one of the major enablers of modern diesel engine performance. To meet the boosting requirements under different operating conditions is the difficulty. The two-stage sequential turbocharging (TSST) system creates the flexibility to select the turbocharging mode so that the engine benefits from efficiency and power density. However, the critical issue at hand is the unstable running, or even worse, misfire, of the engine caused by the abrupt air path shifts during the turbocharging mode switching process. Therefore, the control of the switching process is an indispensable procedure to apply the TSST system. The previous studies mainly focused on turbocharging system parameters. The combustion characteristics during switching process have been underestimated. The combustion process is influenced by the fuel and charging variations during the transient process, and it is unique compared with the steady state. In this paper, the experiments of TSST system switching process were carried out to investigate the transient combustion characteristics, formation mechanism of its fluctuation, and optimal control. The experimental results indicate that the combustion present fluctuation during the direct switching process. The main features are the generation and extinction of premixed combustion, combining the degradation and recovery of mixing-controlled combustion. The cycle history of heat-release center (CA50) presents a 3-phase fluctuation of moving backward from 9.7°CA to11.2°CA, then forward to 6.2°CA, and finally backward to 10.7°CA. The boost pressure trough is the primary factor contributing to incomplete combustion. The lowest gross indicated efficiency of 33.9 % happened at the lowest air-fuel ratio cycle. Based on the corresponding results, the substantial improvement in combustion can be ensured by regulating the switch valves in air path. When the intake switch valve opens 0.9 s later than the exhaust switch valve, the system exhibits minimal parameter fluctuations and the quickest recovery capacity. The coefficients of variation for IMEPg and CA50 are 2.7 % and 4.6 %, respectively, guaranteeing at least 39.7 % fuel conversion efficiency and only 17 cycles to reach the steady state.

Computational fluid dynamic analysis of upper airway procedures in equine larynges.

Computational fluid dynamics (CFD) has proven useful in the planning of upper airway surgery in humans, where it is used to anticipate the influence of the surgical procedures on post-operative airflow. This technology has only been reported twice in an equine model, with a limited scope of airflow mechanics situations examined. The reported study sought to widen this application to the variety of procedures used to treat equine recurrent laryngeal neuropathy (RLN). The first objective of this study was to generate a CFD model of an ex-vivo box model of ten different equine larynges replicating RLN and four therapeutic surgeries to compare the calculated impedance between these procedures for each larynx. The second objective was to determine the accuracy between a CFD model and measured airflow characteristics in equine larynges. The last objective was to explore the anatomic distribution of changes in pressure, velocity, and turbulent kinetic energy associated with the disease (RLN) and each surgical procedure performed. Ten equine cadaveric larynges underwent inhalation airflow testing in an instrumented box while undergoing a concurrent computed tomographic (CT) exam. The pressure upstream and downstream (outlet) were measured simultaneously. CT image segmentation was performed to generate stereolithography files, which underwent CFD analysis using the experimentally measured outlet pressure. The ranked procedural order and calculated laryngeal impedance were compared to the experimentally obtained values. The CFD model agreed with the measured results in predicting the procedure resulting in the lowest post-operative impedance in 9/10 larynges. Numerically, the CFD calculated laryngeal impedance was approximately 0.7 times that of the measured calculation. Low pressure and high velocity were observed around regions of tissue protrusion within the lumen of the larynx. RLN, the corniculectomy and partial arytenoidectomy surgical procedures exhibited low pressure troughs and high velocity peaks compared to the laryngoplasty and combined laryngoplasty/corniculectomy procedures. CFD modeling of the equine larynx reliably calculated the lowest impedance of the different surgical procedures. Future development of the CFD technique to this application may improve numerical accuracy and is recommended prior to consideration for use in patients.

Formation of maritime convergence zones within cold air outbreaks due to the shape of the coastline or sea ice edge

AbstractMaritime cold air outbreaks often feature convergence zones that provide a conducive environment for the development of polar mesoscale cyclones and polar lows. This study examines the formation mechanisms of these convergence zones in cold air outbreaks downstream of a coastline or sea‐ice edge. A simplified configuration in which the coastline or sea‐ice edge is approximated by a line featuring a bend with an angle is examined using analytic solutions and idealised numerical simulations. The bend of the coastline causes differences in the fetch over which air parcels travel, causing a warm wedge of air downstream of the bend due to differential airmass transformations. The warm wedge is associated with a pressure trough that leads to convergence in the presence of surface friction. The analytic model captures this mechanism and compares well with the idealised numerical simulations. Condensational heating associated with moist convection enhances vertical motions and thus intensifies the horizontal convergence. The idealised numerical simulations also reproduce an asymmetry in the vertical shear of the horizontal wind across the convergence zone, which explains the transverse cloud streets downstream to the left of the convergence zone.

A 10-Year Climatology of Midlevel Mesoscale Vortices in China

Abstract The mesoscale vortex (MV) is an important rain-producing system. In this study, the reanalysis data and satellite precipitation products are used to classify MVs into three categories: mesoscale convective vortex (MCV), mesoscale stratiform vortex (MSV), and mesoscale dry vortex (MDV). Then, these three categories of midlevel MVs in China from 2007 to 2016 are investigated. A total of 21 053 MVs are obtained. Most MVs form in the northwest of parent convection, and 45% of MVs generate secondary convection. The Tibetan Plateau is the main MV source region. Steered by the westerlies, MVs mainly move eastward. MCV is active in summer, MDV in winter, and MSV in spring and autumn. MCV diurnal variations are closely related to local topography, and MDVs mainly form around midnight. Composite analyses show that MCVs form near the high-value center of convective available potential energy at the development stage of parent convection. The composite MCV forms near the low pressure trough and the thermal ridge at 500 hPa, and a low-level jet exists to the south of the MCV center. At the initiation and maturity stages of MCV, strong convergence and divergence respectively exist at low levels and 400 hPa. The vortex circulation mainly locates near 500 hPa. Above the vortex is a warm core associated with the latent heat release, and below is a cold anomaly related to the cold pool. In the downshear region, there is strong low-level convergence and ascending motion, higher humidity, and greater latent heat release, which favor the formation of secondary convection.

Experimental Investigation of the Pre-Stall and Stall Evolution in a Centrifugal Compressor With a Volute

Abstract Stall and surge behaviors deteriorate the compressor performance and stability of the operating range. To avoid the effect of stall and surge behaviors, the characteristics of the pre-stall disturbance have been considered in recent years. However, investigations of the pre-stall and stall disturbances in centrifugal compressors remain insufficient owing to the various geometric structures in centrifugal compressors. In this study, a centrifugal compressor with a volute and vaneless diffuser was studied using high-response static pressure measurements and numerical simulations. The pressure disturbance evolution from near-choke to near-surge conditions was obtained, and the characteristics of the pre-stall and stall disturbances were analyzed. The results showed that the compressor instability route could be divided into pre-stall and stall stages, which could be accurately predicted based on the periodic static pressure irregularity and skewness. The pre-stall stage was dominated by the rotating instability (RI) phenomenon, and the frequency of the RI was 43% of the blade passing frequency at 70% Nmax. The experimental results demonstrated that the first onset of RI occurred at the 120 deg–180 deg circumferential position and maintained a local pattern; then, RI occurred over the whole annulus when the flowrate was decreased. RI was induced by the vortex structure attached to the casing wall, leading to a sharp pressure trough in the static pressure trace. The RI exhibited an evolution pattern of initially increasing and then fading, which can be explained by the enlargement and movement of the impeller inlet vortex. The large blockage effect of RI triggered a stall with disturbances at 20% and 80% of the impeller shaft frequency, and these disturbance frequencies had a trend of shifting to one dominant frequency of 22% the impeller shaft frequency. Furthermore, stall cell merging and the coexistence of RI/stall phenomena occurred during the stall stage.

Анализ выхода южных циклонов на территорию Республики Башкортостан

Analysis of the arrival of southern cyclones to the Republic of Bashkortostan / Volobueva O.V., Toptunova O.N., Drobzheva Y.V. // Hydrometeorological Research and Forecasting, 2021, no. 2 (380), pp. 66-76. The results of the analysis of the arrival of southern cyclones to the territory of the Republic of Bashkortostan for the period of 1993-2018 are presented. Typical trajectories of cyclones, areas of their origin, as well as accompanying adverse weather phenomena are identified according to the observational network of the Bashkir Administration for Hydrometeorology and Environmental Monitoring. In 70 % of cases, southern cyclones move through the territory of the republic and leave it in the southern direction. About 50 % of the depressions come to the Republic of Bashkortostan from the Black Sea and its coast. The upper-air field for the arrival of southern cyclones is the front part of the pressure trough with high geopotential height gradients. The arrivals of southern cyclones have a significant impact on the study area and are closely related to the formation of severe hydrometeorological events. Keywords: southern cyclone, typical territories, the Republic of Bashkortost

Atmospheric Boundary Layer—Free Troposphere Air Exchange in the North China Plain and its Impact on PM2.5 Pollution

AbstractThis study presents the first climatology of the atmospheric boundary layer (ABL)—free troposphere (FT) exchange during wintertime in a region covering the North China Plain (NCP) and further discusses its impact on PM2.5 pollution. The exchange flux is calculated based on a mass budget equation using the simulated meteorological field from 2013 to 2019. The mean ABL‐FT exchange is well related to topography and sea‐land distribution, manifesting as strong downward flux over the western/northwestern mountains, moderate exchange along the eastern coastline, and small upward flux over the NCP. Eight weather types are classified to analyze the synoptic influence on ABL‐FT exchange. Strong exchanges exist under the types of “low pressure trough,” “cold front,” and “high pressure” (about 63% of total days), characterized by the downward spatial mean flux of 0.019–0.026 kg m−2 s−1 over the whole research domain. But over the plain area, upward transport is dominant with the air flux from 0.004 to 0.013 kg m−2 s−1 under the first two weather types (about 32% of total days), corresponding to PM2.5 fluxes estimated in the range 0.30–0.54 μg m−2 s−1. This indicates the NCP being an effective pollution source for long‐range transport. We also find that weather types with large downward flux and straightforward winds can refresh the underneath ABL air in about 6 h, which explains the dispersion of air pollution. A typical pollution case illustrates convergence and uplift to the FT of the pollutants in the NCP and the possible influence on downstream air quality.

Australian Northwest Cloudbands and Their Relationship to Atmospheric Rivers and Precipitation

AbstractLarge-scale cloud features referred to as cloudbands are known to be related to widespread and heavy rain via the transport of tropical heat and moisture to higher latitudes. The Australian northwest cloudband is such a feature that has been identified in simple searches of satellite imagery but with limited investigation of its atmospheric dynamical support. An accurate, long-term climatology of northwest cloudbands is key to robustly assessing these events. A dynamically based search algorithm has been developed that is guided by the presence and orientation of the subtropical jet stream. This jet stream is the large-scale atmospheric feature that determines the development and alignment of a cloudband. Using a new 40-yr dataset of cloudband events compiled by this search algorithm, composite atmospheric and ocean surface conditions over the period 1979–2018 have been assessed. Composite cloudband upper-level flow revealed a tilted low pressure trough embedded in a Rossby wave train. Composites of vertically integrated water vapor transport centered around the jet maximum during northwest cloudband events reveal a distinct atmospheric river supplying tropical moisture for cloudband rainfall. Parcel backtracking indicated multiple regions of moisture support for cloudbands. A thermal wind anomaly orientated with respect to an enhanced sea surface temperature gradient over the Indian Ocean was also a key composite cloudband feature. A total of 300 years of a freely coupled control simulation of the ACCESS-D system was assessed for its ability to simulate northwest cloudbands. Composite analysis of model cloudbands compared reasonably well to reanalysis despite some differences in seasonality and frequency of occurrence.

ЭКСТРЕМАЛЬНЫЕ ОСАДКИ ЕВРОПЕЙСКОГО СЕКТОРА АРКТИКИ В ЛЕТНИЙ ПЕРИОД: СТАТИСТИКА И СИНОПТИЧЕСКИЕ МОДЕЛИ

Extreme precipitation in summer is classified in terms of belonging to the certain baseline probability distribution. The Pareto distribution can be used as its approximation. Events deviating from the baseline distribution are represented by the largest daily total precipitation. For them, the compliance with the probability (or the average repetition time) is completely lost, that is, any anomalies can occur, but they do not exceed some limit values typical of the Arctic. Thus, for the entire set of extremes, a specific distribution law of random variables can be introduced, that describes anomalies not exceeding certain absolute values; the presence of the boundary is felt only when approaching it. For 50 analyzed years at each station in the European Arctic, approximately four such anomalies were recorded. Synoptic objects in which super-large precipitation anomalies occur are determined: these are cyclones or pressure troughs with high water vapor content in the air (exceeding ~25 kg/m2) and with mesoscale systems embedded into the fronts, which are characterized by the vertical wind shear.

A measuring technique for intra-osseous pressure

Pulsatile intra-osseous pressures result in bone remodeling, and therefore may affect lesion growth and response to treatment. However, there is no known method used to measure intra-osseous pressures. The purpose of this study is to describe a novel image-guided technique for measuring intra-osseous pressures. This study was IRB-approved and HIPAA compliant. Written informed consent was obtained. Intra-osseous pressure measurements were performed during a CT-guided bone marrow biopsy in eight patients (6 male, 2 female) with mean age 66 ± 13years (median 72, range 45-87) and suspected or known bone marrow disease. Bone marrow pressure measurements were obtained connecting the biopsy needle to a dedicated monitor using a standard arterial line setup. Monitor data was collected at 5-s intervals in order to record continuous pressure measurements for 2min. Pressure measurements were successfully performed in all 8 patients. The mean bone marrow pressures were 36.8 ± 7.2mmHg (median 37.7, range 24.7-47.4). The peak and trough pressures varied by 11%, and the standard deviation of mean pressure measurement varied by 18%. Our findings for marrow pressure measures most closely approximate the pressure profile of the venous system. We describe a novel and minimally invasive technique able to provide functional data of bone marrow. This technique has the potential to provide insights into normal and diseased bone marrow and may be helpful to evaluate features of cystic and vascular tumors that may be amenable to percutaneous treatments.

Investigation on Acoustic Properties of Thruster Chamber with Coaxial Injectors and Plenum Chamber

Based on the URANS equation, a numerical simulation is carried out for acoustic properties of the thruster chamber with coaxial injectors and plenum chamber in a liquid rocket engine. Pressure oscillations with multiacoustic modes are successfully excited in the chamber by using the constant volume bomb method. FFT analysis is applied to obtain the acoustic properties of eigenfrequencies, power amplitudes, and damping rates for each excited acoustic mode. Compared with the acoustic properties in the model chamber with and without an injector as well as with and without the plenum chamber, it can be found that the injector with one open end and one half-open end still can work as a quarter-wave resonator. The power amplitudes of the acoustic mode can be suppressed significantly when its eigenfrequency is close to the tuning frequency of the injector, which is achieved by Cutting down the pressure Peak and Raising up the pressure Trough (CPRT). Compared with the acoustic properties in the model chamber with and without the plenum chamber, it can be found that 1L acoustic pressure oscillation is inhibited completely by the plenum chamber and other acoustic pressure oscillations are also suppressed in a different extent. The injector and plenum chamber have a little effect on the eigenfrequencies and damping rate of each acoustic mode. For multimode pressure oscillation, it is better for tuning frequency of the injector closing to the lower eigenfrequency acoustic mode, which will be effective for suppression of these multiacoustic modes simultaneously.

The Strong, Dry Winds of Central and Northern California: Climatology and Synoptic Evolution

AbstractStrong, dry downslope winds over Northern and central California have played a critical role in regional wildfires. These events, sometimes called Diablo or North winds, are more frequent over the Bay Area and nearby coastal terrain than along the western slopes of the Sierra Nevada, where the highest frequency occurs over the midslopes of the barrier. For the Bay Area, there is a frequency minimum during midsummer, a maximum in October, and a declining trend from November to June. The Sierra Nevada locations have their minimum frequency from February to August, and a maximum from October to January. There is little trend in event frequency during the past two decades over either region. For the Bay Area sites, there is a maximum frequency during the early morning hours and a large decline midday, while the Sierra Nevada locations have a maximum frequency approximately three hours earlier. Before the onset of these downslope wind events, there is substantial amplification of upper-level ridging over the eastern Pacific, with sea level pressure increasing first over the Pacific Northwest and then over the Intermountain West. The coincident development of a coastal sea level pressure trough leads to a large pressure gradient over the Sierra Nevada and Northern California. Diablo–North wind events are associated with below-normal temperatures east of the Sierra Nevada, with rapid warming of the air as it subsides into coastal California. The large horizontal variability in the frequency and magnitude of these events suggests the importance of exposure, elevation, and mountain-wave-related downslope acceleration.

Processes Shaping the Frontal-Scale Time-Mean Surface Wind Convergence Patterns around the Gulf Stream and Agulhas Return Current in Winter

ABSTRACTHigh-resolution satellite observations and numerical experiments have revealed local enhancement of time-mean surface wind convergence along the axes of warm western boundary currents and divergence slightly poleward. A recent study has suggested that frequent occurrence of persistent atmospheric fronts and sea level pressure (SLP) troughs along a sea surface temperature (SST) front are responsible for shaping the frontal-scale wind convergence and divergence contrast as seen in the wintertime climatology near the Kuroshio Extension (KE). These events tend to induce surface wind convergence with moderate magnitude. Through atmospheric reanalysis with high-resolution SST, the present study reveals that, as in the vicinity of the KE, surface wind convergence with moderate magnitude and divergence with moderate-to-extreme magnitude are found to play a primary role in shaping the climatological-mean wind convergence–divergence contrasts across the SST fronts near the Gulf Stream (GS) and Agulhas Return Current (ARC) in winter. In contrast, strong-to-extreme convergence events associated with synoptic-scale atmospheric disturbances are found to yield horizontally uniform time-mean wind convergence. Furthermore, cluster analysis and case studies suggest that persistent atmospheric fronts and SLP troughs are responsible for inducing moderate wind convergence also near the GS and ARC. Thus, these features are consistent with their counterpart near the KE, but the impacts of the ARC tend to be substantially weaker, probably due to its cooler SST among other potential factors.

Numerical evaluation of acoustic characteristics of a thrust chamber with quarter-wave resonators

Acoustic characteristics of a thrust chamber with quarter-wave resonators are numerically studied based on the unsteady Reynolds-averaged Navier-Stokes (URANS) method. Organized pressure disturbance model and constant-volume bomb model are applied as artificial disturbances to excite pressure oscillations in the chamber. Eigenfrequencies and amplitudes of acoustic modes of the chamber are obtained by fast fourier transform (FFT) analysis, while damping characteristics are evaluated by the half-power bandwidth method. Predicted damping capacities of the chamber with and without quarter-wave resonators agree well with experimental results. Pressure oscillations can be controlled by a quarter-wave resonator mainly through reducing the amplitude of target acoustic mode, rather than increasing damping capacity of the chamber. Major damping mechanism of the resonator is cutting down pressure peak of target acoustic mode and raising up its pressure trough (CPRT); therefore the amplitude of target acoustic mode is reduced significantly. Moreover, acoustic energy can be dissipated by vortex at the orifice and by viscosity on the surface of a resonator, which increase damping capacity of the chamber slightly. Under the condition with multi-modes pressure oscillations, a resonator can still suppress pressure oscillations of target acoustic mode through CPRT. However, it may enhance pressure oscillations of other modes due to redistribution of oscillation energy among all acoustic modes.

Moisture sources of extreme precipitation events in arid Central Asia and their relationship with atmospheric circulation

AbstractAlthough moisture is an important factor affecting precipitation in arid Central Asia (ACA), the water vapour sources and their influencing factors are unclear. This study investigates the moisture sources of extreme precipitation events in summer over Northern ACA and in winter over Southern ACA. The results show that in summer over Northern ACA, the water vapour at low and upper atmospheric levels is mainly transported from the North Atlantic and the Arctic Ocean. In addition, the water vapour in winter over Southern ACA is mainly transported from the North Atlantic and the Northern Indian Ocean. Among these sources, anomalous moisture from the North Atlantic is transported to Northern and Southern ACA along the Mediterranean pressure ridge and the Aral Sea pressure trough. In addition, anomalous moisture in Northern ACA from the Arctic Ocean is closely associated with the negative height anomaly near ACA and with the positive height anomaly in the Mediterranean extending northward to the Arctic Ocean; this results in the high‐latitude moisture transporting along the western edge of the cyclone in Northern ACA. In Southern ACA, low‐latitude water vapour from the Northern Indian Ocean is affected by negative and positive height anomalies in Northwest and Southeast ACA. In addition, significant ascending motion occurs in the study area which provides the necessary dynamic conditions for precipitation. The precipitation variations in Northern and Southern ACA are also related to sea‐surface temperature variations, mainly in the North Atlantic, Arctic Ocean, Mediterranean Sea, and Northern Indian Ocean. Therefore, moisture from the North Atlantic, Arctic Ocean, and the Indian Ocean converge and together influence precipitation development during summer over Northern ACA and in winter over Southern ACA.Highlights Arctic Ocean and North Atlantic moisture together influence summer and autumn precipitation in northern arid Central Asia. Indian Ocean and North Atlantic moisture together influence spring and winter precipitation in southern arid Central Asia. Sea‐surface temperatures in the North Atlantic, Arctic Ocean, Mediterranean Sea, and Northern Indian Ocean have positive or negative effects on precipitation in arid Central Asia.

Validity, intra and inter-reliability of manual evaluation of the respiratory muscle strength in asthmatic patients.

This study investigated the concurrent validity, inter and intra-reliability of manual evaluation in Asthma patients. Twenty six asthma patients were assessed. Maximal respiratory muscle strength (Mrms) was tested by inspiratory and expiratory pressure (MIP and MEP, respectively) trough manovacuometer. In addition, Mrms of diaphragm (anterior and posterior), Intercostals (lower and upper portion) and Rectus abdominal were obtained manually, according to Medical Research Council (MRC) scale. Two independents evaluators, previously trained, made both measurements. Reproducibility of Mrms intra-evaluators: anterior diaphragm (ICCs, 0.79 and 0.67); Posterior portion of the diaphragm (ICCs, 0.43 and 0.51); Upper intercostals (ICCs, 0.47 and 0.40); Lower intercostals (ICCs, 0.81 and 0.51) and rectus abdominal (ICCs, 1.0). Inter-reproducibility of anterior diaphragm was low to moderate, while intercostals (upper and lower portion) was relatively low. However, rectus abdominal presented high reproducibility reflecting in almost perfect agreement. In addition, we found positive correlations between MIP versus Lower Intercostals (r = .60, p = .007) and MEP versus rectus abdominal (r = .41, p = .04). In asthmatic patients, manual evaluation of the respiratory muscles is reliable. In addition, maximal respiratory pressures using manometer assessment were related to manual evaluation, in special to diaphragm and rectus abdominal muscles.