Decrease In Mean Velocity Research Articles

Numerical simulations of dam-break flows of viscoplastic fluids via shallow water equations

This paper presents simulations of dam-break flows of Herschel–Bulkley viscoplastic fluids over complex topographies using the shallow water equations (SWE). In particular, this study aims to assess the effects of rheological parameters: power-law index (n), consistency index (K), and yield stress (τc\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ au _{c}$$\\end{document}), on flow height and velocity over different topographies. Three practical examples of dam-break flow cases are considered: a dam-break on an inclined flat surface, a dam-break over a non-flat topography, and a dam-break over a wet bed (downstream containing an initial fluid level). The effects of bed slope and depth ratios (the ratio between upstream and downstream fluid levels) on flow behaviour are also analyzed. The numerical results are compared with experimental data from the literature and are found to be in good agreement. Results show that for both dry and wet bed conditions, the fluid front position, peak height, and mean velocity decrease when any of the three rheological parameters are increased. However, based on a parametric sensitivity analysis, the power-law index appears to be the dominant factor in dictating fluid behaviour. Moreover, by increasing the bed slope and/or depth ratio, the wave-frontal position moves further downstream. Furthermore, the presence of an obstacle is observed to cause the formation of an upsurge that moves in the upstream direction, which increases by increasing any of the three rheological parameters. This study is useful for an in-depth understanding of the effects of rheology on catastrophic gravity-driven flows of non-Newtonian fluids (like lava or mud flows) for risk assessment and mitigation.Graphical abstract

Effects of caffeine on cerebral blood flow

ObjectiveThe objective of the present study is to evaluate whether, after caffeine ingestion, there are variations in blood velocity of the middle cerebral arteries in clinically healthy young people as well as to evaluate whether this variation is dependent on the administered dose. MethodsWe used transcranial Doppler ultrasonography to record blood velocities of the middle cerebral arteries in three groups of 15 clinically healthy young adults each: no caffeine, a45 mg, and 120 mg of caffeine groups. Transcranial Doppler ultrasonography provided simultaneous bilateral velocity of the middle cerebral arteries measurements while participants performed functional tests (hyperventilation and hypoventilation orders) and three cognitive activities (test 1, short-term memory; test 2, solving a vocabulary problem; and test 3, solving a math problem) each in 31-s tests with 1-min rests between them. Participants were assessed before and 30 min after caffeine ingestion. ResultsThere was a significant decrease in mean velocity, peak systolic velocity, end-diastolic velocity, and heart rate after high caffeine intake, except in hyperventilation, which was only observed in peak systolic velocity. With the intake of a lower dose, significant decreases were seen with hypoventilation and with test 1. In hyperventilation, there was only a significant decrease in end-diastolic velocity and heart rate; in test 2, it was found in mean velocity and peak systolic velocity; and in test 3, only in heart rate. ConclusionWith this study, we conclude that caffeine influences the cardiovascular system acutely, interfering with the velocity of the middle cerebral arteries, causing its decrease. We also conclude that this acute effect causes vasodilation of the cerebral arteries, more accentuated with higher doses of caffeine.

The influence of sac centreline on saccular aneurysm rupture: computational study

The geometric characteristics of a saccular aneurysm play a crucial role in its rupturing. This article thoroughly investigates the impact of the sac centerline on aneurysm rupture, with a focus on identifying significant factors related to rupture at different time intervals. The study employs comprehensive computational simulations of six models of the ICA with varying coiling porosities and blood HCTs, using CFD analysis to examine WSS, OSI, pressure, and velocity within the saccular aneurysm for different sac centerlines. The results indicate that higher blood HCT levels lead to increased WSS and pressure values on the aneurysm wall, while OSI and mean velocity decrease. The study also reveals that coiling techniques can significantly reduce the risk of rupture, as decreasing coil porosity (increasing coil permeability) increases OSI and pressure while decreasing WSS and blood velocity within the aneurysm sac.

The Effects of Different Rest Interval Lengths on Acute Quarter-squat Performance in Female

The inclusion of resistance training in the athletic preparation of young athletes is associated with increased time and personal demands. This study compared the effect of different rest interval (RI) lengths on quarter-squat performance in two age groups. Sixteen girls (age 12.20 ± 0.55) and 16 women (age 23.13 ± 2.23) performed three series of 10 quarter squats (10 repetition maximum [RM] load) with different RI times (1 min, 2 min, 3 min) between the three series. Each participant was randomly tested under all the RI conditions. The number of successful repetitions, power, and speed were recorded for each set using by FitroDyne device. The women completed significantly less repetitions in the third set than in the first set for the 2-min and 1-min RIs (9.38 ± 1.54, p = .05 and 8.44 ± 2.42; p = .003, respectively). There was observed a significant decrease in mean power and speed in the 3-min RI between the first and second set and in the 1-min RI between the first and third sets. No significant differences in numbers of completed repetitions and mean power were evident in girls for any RI condition, but there was a significant decrease in mean velocity in the 2-min RI between the first and second sets in this group. These results show that recommendations for adults may be not suitable for girls; the girls’ performance in three sets of 10 quarter squats was less affected by RI than the women’s performance.

The Effect of Climate Change on the Water Supply and Hydraulic Conditions in the Upper Pejibaye River Basin, Cartago, Costa Rica

The consequences of climate change have challenged researchers to generate models and projections to understand climate behavior under different scenarios. In Costa Rica, as in other countries, climate-change (CC) models and projections are essential to make decisions about the management of natural resources, mainly water. To understand climate change’s impact on hydraulic parameters such as velocity, depth, and river surface area, we studied the Pejibaye river basin, located in Jiménez in Cartago, Costa Rica. This watershed is characterized by having more than 90% of its surface area covered by forest. We used the precipitation and temperature data from meteorological stations (2000 to 2009) and climate-change scenarios (2000–2099) to predict the response of the basin in different periods. First, we calibrated (NSE = 0.77) and validated (NSE = 0.81) the HBV hydrological model using ten years of daily data from 2000 to 2009. The climate-change data (2000–2099) were incorporated into the calibrated HBV model. This allowed us to determine the impact of CC on the basin water regime for the periods 2040–2059 (CCS1) and 2080–2099 (CCS2). The IBER mathematical model was used to determine the changes in the hydraulic variables of the river flow. For the CCS1, we determined a 10.9% decrease in mean velocity and a 0.1-meter decrease in depth, while for CCS2, the effect will be an 11.3% reduction in mean velocity and a 0.14-meter decrease in depth. The largest decreases in river surface area per kilometer will occur in May (1710 m2) for CCS1 and April (2250 m2) for CCS2.

Quasi-Two-Dimensional Numerical Analysis of Influence of Taylor Vortex and Eddy Current on Generation Characteristics of Co-axial MHD Energy Conversion Device under Laminar Flow

Quasi-two-dimensional magnetohydrodynamic (MHD) numerical simulation was conducted to clarify the power generation characteristics of a co-axial MHD energy conversion device under laminar flow. The numerical results were compared with one-dimensional theoretical results in the radial direction. For a fixed load resistance, the dependence of output power and efficiency on Hartmann number, which is proportional to the magnetic flux density, was investigated. We found the decrease in mean velocity and the increase in viscous wall shear stress owing to upper and lower walls, the increase in viscous wall shear stress owing to Taylor vortex cells, and the increase in Joule heating owing to eddy current in the MHD numerical simulation compared to those in the one-dimensional theoretical analysis.

Ex vivo observation of granulocyte activity during thrombus formation

BackgroundThe process of thrombus formation is thought to involve interactions between platelets and leukocytes. Leukocyte incorporation into growing thrombi has been well established in vivo, and a number of properties of platelet-leukocyte interactions critical for thrombus formation have been characterized in vitro in thromboinflammatory settings and have clinical relevance. Leukocyte activity can be impaired in distinct hereditary and acquired disorders of immunological nature, among which is Wiskott-Aldrich Syndrome (WAS). However, a more quantitative characterization of leukocyte behavior in thromboinflammatory conditions has been hampered by lack of approaches for its study ex vivo. Here, we aimed to develop an ex vivo model of thromboinflammation, and compared granulocyte behavior of WAS patients and healthy donors.ResultsThrombus formation in anticoagulated whole blood from healthy volunteers and patients was visualized by fluorescent microscopy in parallel-plate flow chambers with fibrillar collagen type I coverslips. Moving granulocytes were observed in hirudinated or sodium citrate-recalcified blood under low wall shear rate conditions (100 s−1). These cells crawled around thrombi in a step-wise manner with an average velocity of 90–120 nm/s. Pre-incubation of blood with granulocyte priming agents lead to a significant decrease in mean-velocity of the cells and increase in the number of adherent cells. The leukocytes from patients with WAS demonstrated a 1.5-fold lower mean velocity, in line with their impaired actin polymerization. It is noteworthy that in an experimental setting where patients’ platelets were replaced with healthy donor’s platelets the granulocytes’ crawling velocity did not change, thus proving that WASP (WAS protein) deficiency causes disruption of granulocytes’ behavior. Thereby, the observed features of granulocytes crawling are consistent with the neutrophil chemotaxis phenomenon. As most of the crawling granulocytes carried procoagulant platelets teared from thrombi, we propose that the role of granulocytes in thrombus formation is that of platelet scavengers.ConclusionsWe have developed an ex vivo experimental model applicable for observation of granulocyte activity in thrombus formation. Using the proposed setting, we observed a reduction of motility of granulocytes of patients with WAS. We suggest that our ex vivo approach should be useful both for basic and for clinical research.

High-flux, adjustable, compact cold-atom source.

Magneto-optical traps (MOTs) are widely used for laser cooling of atoms. We have developed a high-flux compact cold-atom source based on a pyramid MOT with a unique adjustable aperture that is highly suitable for portable quantum technology devices, including space-based experiments. The adjustability enabled an investigation into the previously unexplored impact of aperture size on the atomic flux, and optimisation of the aperture size allowed us to demonstrate a higher flux than any reported cold-atom sources that use a pyramid, LVIS, 3D-MOT or grating MOT. We achieved 2.1(1) × 1010 atoms/s of 87Rb with a mean velocity of 32(1) m/s, FWHM of 27.6(9) m/s and divergence of 59(4) mrad. Halving the total optical power to 195 mW caused only a 20% reduction of the flux, and a 30% decrease in mean velocity. Methods to further decrease the velocity as required have been identified. The low power consumption and small size make this design suitable for a wide range of cold-atom technologies.

Microscopic characteristics of impinging spray sliced by a cone structure under increased injection pressures

Wall-impingement is a serious problem for engine research owing to the possible source of hydrocarbons and soot emission. Therefore, impinging spray becomes the hotpot for investigation, especially for the microscopic characteristics. Droplet behaviors are significantly important to evaluate the atomization for predicting the impingement phenomena, such as stick, spread or splash. Many studies on it for both gasoline and diesel engines were published. However, these researches failed to capture the droplet behaviors clearly in the dense region owing to the overlap of the droplets. Only periphery or far field of the spray was tested. Therefore, a special cone structure named “spray slicer” was designed to cut the spray before observation with the consideration of good observation and less effect on droplet velocity. The experiment was conducted in a constant volume chamber under increased injection pressures between 10 and 30 MPa. Heptane was used as the surrogate fuel injected by a mini-sac injector with a single hole. Microscopic behaviors were recorded by particle image analysis (PIA) method to obtain the droplets size, velocity and minimum distance (Md). Results showed that microscopic behaviors can be observed clearly at different locations. Sauter mean diameter (SMD) and mean velocity decrease with spray development, and the smallest values occur at the periphery. Md increases with spray development owing to better dispersion. Moreover, high injection pressure decreases the droplet size but increases the velocity and Md at a certain degree.

Effect of the Menstrual Cycle When Estimating 1 Repetition Maximum From the Load-Velocity Relationship During the Bench Press Exercise.

García-Pinillos, F, Lago-Fuentes, C, Bujalance-Moreno, P, and Pérez-Castilla, A. Effect of the menstrual cycle when estimating 1 repetition maximum from the load-velocity relationship during the bench press exercise. J Strength Cond Res 36(3): e55-e58, 2022-This study aimed to examine the effect of the ovulatory menstrual cycle (MC) when estimating the 1 repetition maximum (1RM) from the individual load-velocity relationship during the bench press (BP) exercise. Nine resistance-trained eumenorrheic women (age: 28.7 ± 3.6 years) were tested in 3 different phases across the MC: menstrual or early follicular phase (i.e., testing between days 1-3), follicular or late follicular phase (i.e., testing between days 7-10), and luteal or mid-luteal phase (i.e., testing between days 19-21). Each testing trial consisted of an incremental loading protocol against 4 loading conditions (≈50-70-80-90% 1RM) in the concentric-only BP exercise. A smartphone application (MyLift) was used to collect the mean velocity (MV) of all repetitions. The 1RM was estimated from the individual load-velocity relationship by applying a linear regression model as the load associated with an MV of 0.17 m·s-1. In addition, the MV obtained at each %1RM (i.e., from 20% 1RM to 80% 1RM in 20% increments), the load-velocity slope (i.e., the decrease in MV per each 1% of increment in the %1RM), and the y-intercept (i.e., the estimate of MV at 0% 1RM) were computed from the individual load-velocity relationships. No significant differences were observed between the 3 phases of the MC for any of the measured load-velocity relationship parameters (corrected p-value ≥0.495; effect size ≤0.24). The results suggest that the estimation of the BP 1RM from the load-velocity relationship seems not to vary over the 3 different phases of the MC (i.e., menstrual, follicular, and luteal phases).

Numerical simulation of fluid flow and heat transfer in microchannels with patterns of hydrophobic/hydrophilic walls

The presence of a balance between heat transfer rate and pressure drop is an important issue in designing passages of coolant flows to repel high heat flux. This kind of heat transfer is excessively used in cooling microprocessor chips. Application of microchannels leads to an increase in heat transfer and higher efficiency; however, one main challenge of using these channel kinds is the pressure drop, as well as high power requirement for pumping. One effective way of reducing pressure drop is to substitute some parts of the microchannels surface with hydrophobic surfaces. In the present study, a microchannel, with a rectangular cross-section, was modeled by two kinds of hydrophilic/hydrophobic patterns. Governing equations, including continuity, momentum and energy equations, are solved by the use of computational fluid dynamics. The model under investigation includes two transversal and longitudinal patterns. The fluid flow is three-dimensional and incompressible. In addition, hydrophilic surfaces act as rips of flow and, owing to possessing no-slip condition, have an effect on the resultant heat transfer. Comparisons between longitudinal and transversal models show that in the presence of longitudinal models, the pressure drop decrease is 1.5 times more than transversal ones. According to results, using a longitudinal hydrophobic pattern on one of the walls leads to a 12% decrease of mean velocity in a fully developed region. Also, outcome results indicated that the use of hydrophobic models could reduce the required power fluid pump up to 69% and increases heat flux up to 15%.

Unsteady oscillatory MHD boundary layer flow past a moving plate with mass transfer and binary chemical reaction

In this work, we have studied analytically the heat and mass transfer of unsteady MHD natural convective flow past a motioning plate with binary chemical reaction. The flow surface spontaneously moves with unvaried velocity in the flow direction or opposite under the influence of magnetic field. We studied both frequency-dependent effects and “long-time” effects that would require non-practically long channels to be observed in steady flow. We also explored mathematically the important aspects of reactive fluid flow, especially the residence time flow behaviour, scale-up and scale-down procedures. From the present study, it is seen amongst others that temperature is enhanced as the fluid angular velocity rises which leads to maximum temperature in the body of the liquid. It is discovered that mean velocity decrease with a rise in the species reaction and reaction order. The graphical results representing the governing flow parameters effect were presented and discussed. The flow conditions at the wall were also investigated, presented and described.

Impact of Knee Scooter Flexion Position on Venous Flow Rate.

The knee scooter is a commonly used mobility device in the setting of unilateral below-knee immobilization. The bent-knee posture has been shown to decrease venous flow in a seated position, but the knee scooter differs as the patient is weightbearing through the affected extremity. Our goal was to investigate the effects of knee scooter positioning on popliteal venous flow. Duplex ultrasonography was performed to obtain venous diameter and flow velocity of the popliteal vein on healthy subjects over the age of 18 without immobilization. Measurements were performed on the left knee of each subject while standing and with the same knee flexed on the knee scooter, by 2 physicians trained in ultrasound techniques. Mean velocity, peak velocity, vessel diameter, and volumetric flow rate were calculated and t tests were performed for each variable. A power analysis was performed, determining that 9 subjects would provide 80% power with an alpha of 0.05. A total of 13 subjects participated in the study. Mean age was 33 (range 20-56) years, with 6 females and 7 males. Measurements of subjects while standing and on the knee scooter demonstrated a significant decrease in mean velocity (6.5 vs 3.2 cm/s, P < .01) and volumetric flow rate (227.8 vs 106.2 mL/min, P < .01) while subjects were using the scooter. Vessel diameter (0.82 vs 0.78 cm, P = .15) and peak velocities (19.8 vs 14.7 cm/s, P = .19) were not significantly different between standing and kneeling positions. Our findings demonstrated a statistically significant decrease in volumetric flow rate in subjects using a knee scooter device with a flexed knee. Although venous stasis is a known risk factor for DVT, flow rate thresholds for increased thrombus formation are not well defined. The duration of scooter use, or flexed knee positioning, may have some effect on the degree of stasis. This finding should caution orthopedists to consider the risk attributed to the knee scooter as part of their overall patient assessment. Level II, therapeutic, comparative study.

A Randomized Trial of Oral and Transdermal Rivastigmine for Postural Instability in Parkinson Disease Dementia.

The objective of this study was to compare the efficacy and safety of oral and transdermal rivastigmine for postural instability in patients with Parkinson disease dementia (PDD) who were candidates for a cholinesterase inhibitor. The primary outcome was the change in mean velocity of the center of pressure (CoP) after 6 months. Secondary outcomes included structural parameters of dynamic posturography, clinical rating scales, and adverse events requiring dose reduction. Patients with PDD were randomized in a 1:1 ratio to oral or transdermal rivastigmine with target doses of 6 mg twice daily and 9.5 mg/10 cm daily, respectively. Outcomes were assessed at baseline and 6 months. Results were compared within and between groups. Nineteen patients completed the study (n = 8 oral, n = 11 transdermal). Mean daily doses of 9.4 (±1.5 mg) and 16.4 (±3.6 mg) were achieved in the oral and transdermal groups, respectively. The transdermal group demonstrated a significant 15.8% decrease in mean velocity of CoP (patch: P < 0.05; oral: 10.0% decrease, P = 0.16) in the most difficult scenario (eyes closed with sway-referenced support). There was no difference between groups (P = 0.27). For structural parameters, significant improvements were seen in the mean duration of peaks (patch) and interpeak distance (oral) in the most difficult condition. No changes were observed in clinical rating scales. Six patients experienced nonserious adverse events requiring dose reduction (n = 5 oral; n = 1 transdermal). Rivastigmine may improve certain elements of postural control, notably the mean velocity of CoP. Benefits appear to be more obvious under more taxing sensory conditions.

A study of the rheology and micro-structure of dumbbells in shear geometries

We study the flow of frictional, inelastic dumbbells made of two fused spheres of different aspect ratios down a rough inclined plane and in a simple shear cell, using discrete element simulations. At a fixed inclination angle, the mean velocity decreases, and the volume fraction increases significantly with increasing aspect ratio in the chute flow. At a fixed solid fraction, the shear stress and pressure decrease significantly with increasing aspect ratio in the shear cell flow. The micro-structure of the flow is characterized. The translational diffusion coefficient in the normal direction to the flow is found to scale as Dyy=bγ̇d2, independent of aspect ratio, where b is a constant, γ̇ is the shear rate, and d is the diameter of the constituent spheres of the dumbbells. The effective friction coefficient (μ, the ratio of shear stress to pressure) increases by 30%-35% on increasing the aspect ratio λ, from 1.0 to 1.7, for a fixed inertial number I. The volume fraction (ϕ) also increases significantly with increasing aspect ratio, especially at high inertial numbers. The effective friction coefficient and volume fraction are found to follow simple scalings of the form μ = μ(I, λ) and ϕ = ϕ(I, λ) for all the data from both systems, and the results are in reasonable agreement with kinetic theory predictions at low I. The computational results are in reasonable agreement with the experimental data for flow in a rotating cylinder.

Effect of hip and knee position on nerve conduction in the common fibular nerve.

The aim of this study was to measure the influence that hip and knee position have on routine fibular motor nerve conduction studies. Healthy subjects under age 40 were recruited (n = 24) to have fibular nerve conduction studies completed in various positions, using hip extension-knee extension as a control. A mean increase in conduction velocity of 2.5 m/s across the knee (P = 0.020) was seen during hip flexion compared with hip extension. A mean decrease in velocity of 1.6 m/s through the leg segment (P = 0.016) was seen during knee flexion compared with knee extension. This study shows that the optimal position of the leg during fibular nerve studies is with the hip in flexion and knee in extension, to more accurately reflect nerve length for velocity calculations. This may have implications for other peripheral nerves with respect to proximal joint position affecting calculated velocity. Muscle Nerve 56: 519-521, 2017.

DESCRIÇÃO ESTATÍSTICA DO CICLO DIÁRIO DO VENTO NOS PRIMEIROS 100 METROS DE ALTURA DA C.L.P. NA LOCALIDADE DE COLONIA EULACIO, URUGUAI

In this work is presented a statistical description of wind profile in the first 100 m of height of the Planetary Boundary Layer, taking account the measurements in the tower Colonia Eulacio Uruguay. This tower has high vertical resolution of wind velocity measurements, form 10.1 m to 101.8 m. Thermometer are installed in 3.4 m and 100.8 m, also the tower is equipped with wind vane and pyranometer. We present the diurnal cycle of mean wind, intensity of turbulence in dependence of height, also standard deviation of direction is described as a measure of turbulence in wind. Stability state is computed with vertical gradient of temperature. Before sunrise (unstable condition) is seen a decrease in mean velocity of top levels (81.8 m and 101.8 m) and increase in lower levels (10.1 m and 25.7 m). Higher dispersion in dT/dz can be seen during night time (stable condition), superadiabatic values -0.02 ◦C/m can be seen during daytime with slow dispersion. Intensity of turbulence decrease with height, for all stability conditions, is seen a increase in intensity of turbulence for unstable condition.

Characteristics of the pulsating flow and heat transfer in an elbow tailpipe of a self-excited Helmholtz pulse combustor

A valveless self-excited Helmholtz pulse combustor with an elbow tailpipe was designed. The pressures along the tailpipe and the internal and external elbow section were measured. The pulsating flow in the elbow tailpipe was numerically simulated by FLUENT. Numerical simulation results show that the mean velocity decrease with the velocity amplitude along the tailpipe. The mean and amplitude of area-averaged pressure and internal and external elbow pressure decrease along the tailpipe. The mean and amplitude of the internal elbow pressure are less than those of the external elbow pressure. The simulation results are in good agreement with the experimental data. The mass-averaged velocity-reversing, Dean vortex forming, shedding and reforming process and periodical Dean vortex shapes and vortex core positions contribute to convective heat transfer enhancement.

Evaluation of acute rejection after liver transplantation with acoustic radiation force impulse and color Doppler flow imaging

Objective To investigate the value of acoustic radiation force impulse (ARFI) and color Doppler flow imaging (CDFI) in the diagnostic of acute rejection (AR) after liver transplantation. Methods B mode ultrasound, CDFI and ARFI exams were performed on fifty-eight patients who was diagnosed with AR through liver biopsy in our hospital. The liver allograft size, mean velocity of portal vein, hepatic vein spectrum waveform and shear-wave velocity were obtained and compared with the results of 30 healthy subjects as control group. Results Compare to control group, the AR group had a significant increase in liver allograft, decrease in mean velocity of portal vein, the elimination of triphasic wave of hepatic vein, and a significant increase in shear-wave velocity (P=0.000, 0.000, 0.007, 0.000, respectively). The correlation coefficient between four criteria and grouping was 0.478, 0.557, 0.286, 0.483, respectively. The area under ROC curves for diagnosing AR using the four criterias mentioned above was 0.914. Conclusions Combination of CDFI and ARFI in diagnosing of AR after liver transplantation has higher sensitivity and accuracy. Key words: Ultrasonography; Liver transplantation; Transplant rejection; Acoustic radiation force impulse technique

Beneficial effect of Danggui-Shaoyao-San, a traditional Chinese medicine, on drowsiness induced by chronic restraint stress

Danggui-Shaoyao-San (DSS), a famous Chinese complex prescription, has a long history of treating dysmenorrhea in China. Recent studies showed that DSS had its therapeutic efficacy on depression. In the present study, the effects of aqueous extract of DSS were examined to investigate the pharmacological basis for its therapeutic efficacy on chronic restraint stress (CRS)-induced sleep disorder. Mice were treated with DSS by gavage administration at doses of 0.625g/kg, 1.25g/kg and 2.5g/kg for 10 days. Sleep time and sleep latency were measured 24h after the CRS procedures using the sodium pentobarbital-induced sleep test. Open field test was used to evaluate the mice locomotion and anxiety/depression levels. Body weight and food intake were determined as well. The results showed that DSS dose-dependently prolonged latency and decreased sleep time of CRS mice, reversed CRS-induced decrease of mean velocity, the percentage of center distance and time in central area, as well as decreased body weight and food intake. In conclusion, our results suggest that DSS has exerted measurable therapeutic effects in hypersomnia induced by chronic restraint stress.