Head Drop Research Articles

Firefighter With Co-Morbid Psychogenic Non-Epileptic Seizures and Post-Traumatic Stress Disorder Treated With Prolonged Exposure Therapy: Long-Term Follow-Up

Psychogenic non-epileptic seizures (PNES), are events that resemble epileptic seizures but lack electrophysiological or clinical evidence for epilepsy. Instead, they are psychogenic in origin. These episodes tend to occur with alterations in consciousness and bodily functions and are the result of mechanisms of conversion. Psychological trauma and post-traumatic stress disorder (PTSD) are prevalent among patients with PNES. This is a case report of a 32-year-old male who began treatment 1-year after developing PTSD followed some months later by PNES. His seizures were characterized by contorted movements of the head and neck, guttural sounds, and left sided movements or whole-body arching and were accompanied by frequent falls and injuries. They were usually brief but occurred daily. Psychotherapy had been discontinued because violent seizures often interrupted the sessions. He was treated with prolonged exposure (PE) at a PNES program and by the last session, had achieved an improvement in his seizure frequency (one every 4–6 days rather than daily episodes). This allowed him to begin therapy with a local therapist. Two years after completing treatment, the patient returned for a follow up visit. At that point, his seizure frequency, was one per month which shows he sustained and improved on this symptom. Former head drops, and grunting sounds disappeared, and he was no longer using a cane to ambulate. From an emotional standpoint (PTSD, suicidality, anxiety, quality of life), the patient had achieved and maintained a much healthier level of functioning (though no change on alexithymia, anger, depression, and trait anxiety).

Numerical simulation of the performance of a centrifugal pump with a semi-open impeller under normal and cavitating conditions

An important flow mechanism that can affect the performance and efficiency, as also the maintenance cost of centrifugal pumps is cavitation. Scientific research has been focusing on the mechanisms that govern cavitation in order to develop experimental and numerical tools that are able either to detect the phenomenon or to anticipate its appearance. In this study, a computational model is used in order to study the cavitation performance of a radial flow centrifugal pump with a semi open impeller. The numerical model includes and studies the effects of the blade tip clearance and its thickness, and it is validated against corresponding laboratory measurements and visualization data obtained for this pump under normal and cavitating flow conditions. The total head drop variation curves versus cavitation parameter are extracted both numerically and experimentally, and compared for various pump loading conditions with satisfactory agreement. A non-periodic pattern of flow and cavitation bubbles between the impeller blades, which is caused by the inlet pipe bending, is also well reproduced by the model. The numerical results display in detail the complex flow field and the secondary flows developed in the tip clearance area, close to the blades leading edge. The effects of the latter on the onset and development of cavitation at the suction side of the impeller, as well as on the backflow cavitation phenomenon are presented and analyzed. Backflow cavitation is found to affect the suction ability of the pump, especially for moderate cavitation conditions, as far as the pressure differences between the two blade sides remain significant.

Biocolmation and the finite element modeling of its influence on changes in the head drop in a geobarrier

The influence of the biocolmation of the geobarrier for organic waste storage on the values of head drops has been investigated. A mathematical model of filtration of organic substances taking into consideration the biocolmation effect was formed. The mathematical model contains the equation of filtration under conditions of variable porosity. In addition, the mathematical model includes the equation of transfer of organic chemical substances in pore fluid and the equation of dynamics in bacteria biomass in a porous medium based on the Monod equation. The problem in the region with a thin inclusion was solved by the method of finite elements. The schematic algorithm of finding an approximate solution of the boundary problem, including the scheme of discretization over time, is presented. Numerical experiments were conducted with an analysis of their results. In particular, the tables have been given of the values of heads and their drops on inclusions when biocolmation is neglected and the values of heads and their drops on inclusions while taking into account biocolmation at specific moments of time. The numerical experiments showed that the existence of microorganisms in soil pores significantly influences the values of heads at the top and at the bottom of a geobarrier. In particular, relative changes in head drops, in comparison with the case of disregarding the influence of microorganisms, can reach 54.8 % towards an increase. Such differences, in turn, lead to a change in the estimation calculations of the propagation of waste storage contamination into groundwater. They can also cause negative changes in the stressed-strained state of a soil array in the vicinity of a geobarrier as a type of a thin inclusion and lead to the intensification of shear processes. At the same time, due to the nonlinearity of influences and complex interdependence among processes, it is not possible to predict such values and their differences without computer simulation and mathematical modeling

Coronary spastic angina after the administration of intravenous immunoglobulin in myasthenia gravis: a case report

BackgroundMyasthenia gravis (MG) is an autoimmune disease caused by antibodies that block or destroy nicotinic acetylcholine receptors at the neuromuscular junction. Most of MG patients need immunosuppression agents in addition to treatments that alleviate the symptoms. Intravenous immunoglobulin (IVIg) and plasma exchange are specific treatments given to patients with severe MG and myasthenia gravis crisis. IVIg therapy can cause an increase in serum viscosity; therefore, the risk for thromboembolic events, such as stroke, myocardial infarction, and pulmonary embolism, are reported after IVIg therapy.Case presentationAn MG patient was treated with pyridostigmine bromide and prednisolone. The patient’s symptoms worsened 26 days after the commencement of treatment and was presented with head drop and dyspnea. The patient was diagnosed with MG crisis and IVIg was initiated. However, the patient reported chest pain and dyspnea 3 days after IVIg had started. An electrocardiogram (ECG) revealed ST elevations in leads II, III, and aVF. A cardiac catheterization was performed and stenosis, obstruction, and sclerosis were ruled out. Glyceryl trinitrate relieved the patient’s symptoms, suggesting coronary spastic angina (CSA).ConclusionsWe report the first case of CSA after IVIg. Practitioners should be aware of the potential risks of CSA when administering IVIg for MG patients, in particular in old patients with vascular risk factors.

Particle image velocimetry measurement of flow fields in a mixed-flow pump with non-uniform tip clearance

In order to better understand the flow characteristics of mixed-flow pump with non-uniform tip clearance, a test rig is established and the flow fields of various cross section in impeller are studied based on particle image velocimetry technology. The velocity vector distributions of three cross sections, e.g., impeller blade inlet, middle and outlet, were measured. The influences of flow rate and eccentricity on the flow fields of mixed-flow pump with non-uniform tip clearance were analyzed, and the relative velocity distribution of different positions at the same cross section is quantitatively discussed. The results show that the external characteristics have been greatly affected by the eccentricity of impeller. There is a significant negative correlation between eccentricity and efficiency. The maximum head and efficiency drop of eccentric impeller reach 11% and 20% separately. With the increase in eccentricity, the secondary flow phenomenon increases, such as backflow and vortex flow in impeller flow passage. Vortex structure is easily formed in the end wall region, which will give rise to backflow and even blocks the flow passage near impeller hub. The energy loss increases continuously in this process which is the main reason for the significant drop in efficiency. The research results are instructive for revealing the flow characteristics of flow fields of mixed-flow pump with non-uniform tip clearance.

An efficient numerical scheme for the thermo-hydraulic simulations of thermal grids

Renewable and smart energy systems require district heating and cooling grids able to operate with variable flow rates, to manage different supply temperatures, and to support distributed energy production involving bidirectional flows. Due to these requirements, accurate and effective thermo-hydraulic models are essential to correctly simulate the flow rates, the head drops and the temperature transients for supporting the design, management and optimisation of thermal distribution networks. In this article, an efficient numerical scheme for the simulation of thermal grids based on a thermo-hydraulic model with a quasi-dynamic approach is proposed. Global gradient algorithm of Todini together with a uniformly distributed representation of demand along the pipes is used for steady-state hydraulic simulations of the networks modelled according to the graph theory. The temperature distribution is computed by solving a first order hyperbolic PDE which accounts for heat advection in the flux term and heat dissipation in an algebraic source term. A very efficient second-order Eulerian-Lagrangian finite volume scheme is employed on a staggered mesh, which evolves in time the temperature distribution starting from the velocity distribution given by the hydraulic solver. The usage of a Eulerian-Lagrangian algorithm for the discretisation of the convective terms, allows the proposed model to be unconditionally stable for every time step size. As such, the main advantages of the proposed model are the flexibility due to the admissibility of any spatial-temporal discretisation, the second order accuracy provided by both the demand schematisation and the thermo-hydraulic solver, and the computational efficiency guaranteed by the decoupled modelling approach. The resulting algorithm is extensively validated on four tests consisting of thermal grids of various complexity that have been carefully designed in order to capture different features and behaviours of the model. The accuracy of the results in terms of velocity, pressure and temperature is tested by separately checking the symmetry, the advection term, the heat loss component and, finally, by simulating a complex grid configuration with multiple heat sources. The article aims to present a proof-of-concept concerning a breakthrough numerical scheme for the efficient thermo-hydraulic simulation of pipeline networks, which proves to be suitably implemented in the modelling of district heating and cooling networks.

3D simulation of gas-laden liquid flows in centrifugal pumps and the assessment of two-fluid CFD methods

An assessment of a two-fluid model assuming a continuous liquid and a dispersed gas phase for 3D computational fluid dynamics (CFD) simulations of gas/liquid flow in a centrifugal research pump is performed. A monodisperse two-fluid model, in conjunction with a statistical eddy-viscosity turbulence model, is utilized. By a comprehensive measurement database, a thorough assessment of model inaccuracies is enabled. The results on a horizontal diffuser flow reveal that the turbulence model is one main limitation of simulation accuracy for gas/liquid flows. Regarding pump flows, distinctions of single-phase and two-phase flow in a closed and semi-open impeller are figured out. Even single-phase flow simulations reveal challenging requirements on a high spatial resolution, e.g., of the rounded blade trailing edge and the tip clearance gap flow. In two-phase pump operation, gas accumulations lead to coherent gas pockets that are predicted partly at wrong locations within the blade channel. At best, a qualitative prediction of gas accumulations and the head drop towards increasing inlet gas volume fractions (IGVF) can be obtained. One main limitation of two-fluid methods for pump flow is figured out in terms of the violation of the dilute, disperse phase assumption due to locally high disperse phase loading within coherent gas accumulations. In these circumstances, bubble population models do not appear beneficial compared to a monodisperse bubble distribution. Volume-of-Fluid (VOF) methods may be utilized to capture the phase interface at large accumulated gas cavities, requiring a high spatial resolution. Thus, a hybrid model, i.e., a dispersed phase two-fluid model including polydispersity for flow regions with a dilute gas phase, should be combined with an interphase capturing model, e.g., in terms of VOF. This hybrid model, together with scale-resolving turbulence models, seems to be indispensable for a quantitative two-phase pump performance prediction.

Underground Pumped Storage Hydropower Case Studies in Belgium: Perspectives and Challenges

To avoid the geographical and topographical prerequisites of the conventional pumped hydro energy storage, the use of underground cavities as water reservoirs allows countries without steep topography, such as Belgium, to increase the potential of the energy storage capacity. Belgium abounds in disused mines and quarries convertible into water basins. In this article, two Belgian case studies are presented and discussed for their singularity. A slate quarry in Martelange is discussed in technical aspects proposing three operating scenarios. Moreover, a preliminary economic analysis of the underground pumped storage system and a greenhouse gas emission evaluation for the storage system’s lifetime are presented. The analysis for a 100 MW power plant estimates a total initial investment of over 12 million euros and two million of CO2 avoided over its lifetime. This article also proposes the use of the coal mine 500 m deep of Pérronnes-lez-Binche. The mine representation discussed here offers a high energy capacity, but the substantial head drop (from about 500 to 200 m) challenges the selection of the hydraulic turbomachinery. A 1D simulation computed in SIMSEN draws out the behaviour of the unusual hydraulic configuration of turbines in series.

A MINLP Model for Optimal Localization of Pumps as Turbines in Water Distribution Systems Considering Power Generation Constraints

Pressure reducing valves (PRVs) are commonly used for pressure control in water distribution systems (WDSs) by means of dissipating the pressure excess. The use of pumps as turbines (PATs) is an alternative and more favorable system since they not only control the system pressure to decrease water leakage, but also utilize the pressure excess to generate electrical energy. The optimal localization of PATs can be casted into a mixed-integer nonlinear program (MINLP) where binary variables are used to represent the presence of PATs on links. Most of the available MINLP models for optimal PAT localization adopted the optimization approaches for PRV localization without considering the bound constraints on flow rates and heads of PATs. As a result, such an optimization model may make PATs delivering a non-desired output. In this paper, we propose a new MINLP model for optimal PAT localization. Instead of using a constraint on the maximum number of PATs to be placed in a WDS, new constraints relating to the minimum power generated by PAT are introduced to find links having adequate flows and head drops for placing PATs. Moreover, constraints are used to restrict flows and heads of PATs to their feasible operating range, so that the problem can be efficiently solved. The proposed MINLP model is applied to the optimal localization of PATs for a WDS benchmark and a real-world WDS in Vietnam. The results demonstrate that the new MINLP model can efficiently identify optimal locations for PAT placement where the specified working range and minimum power generated by the PATs are ensured.

Susceptibility of shallow groundwater aquifers to water logging, case study Al Marashda area, West Nile Valley, Qena, Egypt

Attempts were carried out to delineate the areas where the aquifer is vulnerable to water logging, head drop and pollution in the new and old reclamation areas as well. All of the hydrological, geophysical and soil factors were incorporated in the DRASTIC model. Parameters included are; depth to water, net recharge, aquifer media, water salinity, thicknesses and resistivity of successive geoelectrical layers soil media, topography and impact of the vadose zone. Saturated soil hydraulic conductivity varies from 4.43 X10-4 to 243 X10-4 m/sec. Groundwater is supplied from the gravel sand saturated sediments belonging to the Quaternary aquifer. The aquifer thickness rangs from 60 to 120 m. Groundwater depths are gradually increased from 2 m in north to about 72 m in the southern area. Groundwater levels are ranging from 58 m a.s.l. to 74 m a.s.l. Transmissivity is ranging from 155 m2/day to 420 m2/day. Applying the DRASTIC model reveals that there are five vulnerable classes characterizing the study area. Very low and Low vulnerable areas characterize the southern area located near the table land area. Medium vulnerable area present at the pediment area just above the old cultivated lands and extends through the old cultivated lands East of Al Marashda area where groundwater depths are ranging from 5 m - 40 m and recharge is essentially from excess irrigation water. A very high and high vulnerable area is located in the old cultivated lands where groundwater is very shallow (< 5 m) and recharge is very high from excess irrigation water and percolation from surface water systems.

DESIGN AND ANALYSIS OF UNDER TUNNEL IN IRRIGATION CANAL SYSTEM

Modern irrigation equipment and adequate structure are required to do an efficient job of irrigation. When these requirements are met, water can be controlled easily and many man hours of labor with a shovel will be saved. Control begins at the diversion dam which is built into the stream or channel. It diverts the desired amount of water to the ditches and permits surplus or high water to by-pass without damage to the dam or the channel. Head gates, checks, drops, waste way and other devices are required at critical points in the ditch through which the water flows to the farm. These are necessary to prevent washouts and channel erosion. Every farm requires a different set of structures and equipment. For this reason the devices fat controlling irrigation should be carefully planned to fit the needs of the farm. Some of the needed structures can be built in place by the farmer' out of concrete and wood. Many of the smaller structures such as head gates and turnouts are now being made commercially of concrete and steel. When the canal is running in partial or full embankment and there is no sufficient head way to pass the discharge of drain below the canal then an Under Tunnel may be proposed. That is if the (MFL +Freeboard) of drain is above the bed level of canal, then a barrel will be provided below the canal bed level by depressing the bed level of the drain. The main purpose of preparing this structure design is to provide safe passage of canal water across the stream, valley, river or nallas to farming lands to create better irrigation potential.

0012 REM Sleep in Ostrich Chicks

Abstract Introduction It was reported that adult ostriches displayed the longest REM sleep episodes (up to 5 min) and more REM sleep (24% of the nighttime) than any other avian species. In all mammals studied so far REM sleep predominates at early age suggesting it promotes development of the brain. The aim of this study was to examine REM sleep in ostrich chicks. Methods EEG, electrooculogram and electromyogram of the neck muscles were recorded in 4 chronically implanted 2–3 month old ostrich chicks over 3 nights. The last night was scored in 4-sec epochs for waking, nonREM and REM sleep. Results NonREM sleep and REM sleep in the ostrich chicks occurred when they were sitting or lying with the head held above the ground or rested on the ground. REM sleep was characterized by distinct rapid eye movements, head drops and eye closure. The amplitude of the EEG during episodes of REM sleep ranged between low voltage EEG, as recorded during quiet waking and high voltage slow waves, as recorded during nonREM sleep EEG. The ostrich chicks spent on average 70.7 + 2.2% of the nighttime in nonREM sleep and 12.3 + 3.9% in REM sleep. The episodes of REM sleep lasted on average 9 + 1 sec and ranged between 4 and 36 sec. Conclusion Similar to adult birds, 2–3 mo old ostrich chicks displayed a “mixed” sleep state which has features of both slow wave sleep / nonREM and REM sleep, as we have described in the platypus and echidna. An unexpected result of this study is the total amount and duration of episodes of REM were considerably smaller than has been reported in adult ostriches. More studies need to be done on the developmental and environmental determinants of REM sleep in the ostrich. Support The Russian Foundation for Basic Research (18-04-01252) and HL148574

Numerical study on the cavitation phenomenon for the head drop and unsteady bubble patterns with a difference in the incidence angle of a mixed-flow pump

In this study, two types of mixed-flow pump models exhibiting different suction performances were investigated to understand the cavitation characteristics of head drop gradients due to the decrease in inlet pressure. Both models were designed with the same specifications except for the shroud inlet blade angle and inlet radius which directly affect the incidence angle. The steady- and unsteady-state analyses were performed using ANSYS CFX, and the results of both models were compared. Bubble generation and patterns were systemically represented at the design flow rate to observe their influence on suction performance. Furthermore, experimental tests were performed to validate the numerical results. From the results, the head drop gradient can determine the suction performance of mixed-flow pumps. The amount and shape of the bubbles concerning the suction performance of a mixed-flow pump exhibit significant differences with the changes in time and inlet pressure. The patterns of generated bubble are not stable even for each blade.

103 Atypical Progressive Bulbar Palsy presenting with Dropped Head

Typical amyotrophic lateral sclerosis (ALS) presents on neurological examination with specific signs of upper and lower motor neuron degeneration (Brooks et al, 1995), which can account for 85% of patients with ALS (Turner and Talbot, 2013). There are different types of clinical presentations, including progressive bulbar palsy (PBP), Limb-onset ALS, progressive muscular atrophy (PMA) and upper motor neuron (UMN) predominant ALS. PBP has mainly brainstem signs. There are a few case reports of dropped head syndrome in ALS, mainly in patients with the limb involvement variant. Case report. A 56 year old right-handed male, presented to the clinic with four months of dysphagia to liquids and solids, neck pain and progressive neck weakness causing constant drop head. No dysarthria or other neurological symptoms, no dyspnea. Neurological examination: Cranial Nerve (CN) CN XII: Nasal voice, bilateral atrophy of the tongue with tremor and fasciculations. Motor: Diffuse atrophy and decreased tone of the sternocleidomastoid and trapezii bilaterally, strength: 2/5 in neck flexors and extensors. Sensory: Hypoesthesia of the tongue. The rest of his neurological examination was normal. Labs: Routine blood work, thyroid function tests, collagen vascular work-up, and protein electrophoresis were normal. Creatine Phosphokinase (CPK) and Acetylcholine Receptor Antibodies (AChR Ab) were negative. Brain and Spinal Cord MRI: Showed mild brainstem, cerebellar and cervical spinal atrophy. Patients with ALS initially present with symptoms localized to the limbs or bulbar muscles. A very small percentage 1-2% of ALS patients had neck muscle weakness with head drop (Jokelainen et al, 1977; Gourie-Devi et al, 2003). However, in all the previously reported cases, the patients had limb involvement at the time of presentation which was absent in this case, and the head drop occurred after the onset of symptoms (Lange et al, 1986; Katz et al; 1996). Dropped head syndrome can be seen in inflammatory myopathies, myasthenia gravis, facioscapulohumeral muscular dystrophy, spinal muscular atrophy, nemaline myopathy and carnitine deficiency (Umapathy et al, 2003) but ALS should also be considered in patients with atypical presentations.

Numerical simulation on role of the rotating stall on the hump characteristic in a mixed flow pump using modified partially averaged Navier-Stokes model

Insufficient understanding of flow instability interaction between hump characteristic and the rotating stall is a major problem in the application of mixed flow pumps. In this paper, the unsteady flow characteristics of a mixed flow pump are studied numerically to understand the hump characteristic generating mechanism using a modified SST k-ω partially averaged Navier-Stokes (MSST PANS) model. The predicted pump characteristic curves show good agreement with experimental data. Fundamental results on time-averaged flow pattern and energy loss distributions depict that the substantial rise of energy loss in the pump impeller is the main reason for the hump characteristic. Detailed flow structures show the peak regions of circumferential vorticity (Ωθ) and boundary vortex flux (BVF) are located at the blade tip near the trailing edge (TE) and leading edge (LE). Further analysis on the flow angle and blade loading are carried out. The results indicate that the peak region located near the LE of spanwise = 0.8 and streamwise = 0.3 is the source of the rotating stall evolution. In this process, the substantial reduction in the blade loading occurs near the LE, eventually induces the head drop. Finally, pressure fluctuations analysis depicts that low-frequency signal is observed induced by the rotating stall evolution.

Bracing to treat dropped head syndrome in cancer patients: A retrospective review.

ABSTRACT Introduction The objective of this study is to describe the use of postural bracing to treat dropped head syndrome (DHS) in cancer patients. The study design is a retrospective review over a 3-year period of cancer patients who presented to a cancer physiatry outpatient practice for treatment of DHS. Patients were individuals with a history of head and neck cancer, Hodgkin lymphoma, or other cancer with a diagnosis of DHS. Materials and Methods The treatment intervention was postural bracing with either a figure-of-eight orthosis with or without a lumbosacral orthosis or a thoracolumbosacral orthosis. Results Subjective, patient-reported improvements in pain, posture, and neck or back strength in addition to objective improvements in physical examination were made. Out of 41 patients initially evaluated for DHS who followed up in brace clinic, 61% reported a positive response to bracing with 17.1% reporting improvement in neck or back strength, 17.1% reporting improvement in pain, and 39% reporting improvement in posture. Discussion In this study, we present a successful alternative to treat DHS through the use of active bracing. The technique of active bracing in this population theoretically strengthens the weak muscles in head drop and improves head position. Maintenance of these achievements, although not directly studied in this project, must be performed through a regular home exercise and bracing program as patients likely have a tendency to weaken again given prior oncologic treatments. Conclusions Active postural bracing using a combination of a figure-of-eight brace with or without a lumbosacral orthosis or a thoracolumbosacral orthosis in conjunction with physical therapy can help improve the posture, pain, and neck and back strength of cancer patients with DHS.

Energy characteristics of mixed-flow pump under different tip clearances based on entropy production analysis

In order to investigate the effect of impeller tip clearance on the internal flow fields and the hydraulic losses in mixed-flow pump, the entropy production method with computational fluid dynamics (CFD) is employed to analyze the energy losses in a low specified number mixed-flow pump with guide vane. The results show that the size of tip clearance is closely related to the external characteristic performance of mixed-flow pump, and the effect of tip clearance on the flow fields of mixed-flow pump is obvious at design flow rate condition. When the tip clearance raises from 0.2 mm to 1.1 mm, the head drop loss coefficient increases 1.62 times in the impeller. As the tip clearance augments from 0.2 mm to the 1.1 mm, the total entropy production in impeller increases by 142%. Whereas, the total entropy production in guide vane descends by 21.8% slightly. It indicates that the increase of tip leakage flow (TLF) may increase the energy losses in impeller but the hydraulic losses in guide vane is suppressed to some extent as a result of an existence of TLF. Therefore, for the sake of improving the energy performance of mixed-flow pump, it is necessary to take the scale of blade tip clearance into account and consider optimizing the hydraulic design structure of guide vanes comprehensively to match the tip clearance.

Comparison of sedative and some cardiopulmonary effects of intramuscular medetomidine or medetomidine–tramadol in dogs

ObjectiveTo evaluate the clinical and physiologic effects of intramuscular (IM) administration of medetomidine with and without tramadol in dogs. Study designProspective experimental study. AnimalsA group of eight mixed breed dogs of both sexes, aged 1–2 years, weighing 16.0 ± 0.6 kg. MethodsEach dog was studied twice at ≥1 week interval. Medetomidine (5 μg kg–1; treatment M) was administered IM alone or with tramadol (4 mg kg–1; treatment MT). Sedation was scored by a system that included vocalization, posture, appearance, interactive behaviors, resistance to restraint and response to noise. Times from drug administration to ataxia, impaired walking, head drop, sternal and lateral position and standing were recorded. Sedation score, heart rate, respiratory rate, rectal temperature, end-tidal carbon dioxide (Pe′CO2), hemoglobin oxygen saturation and mean noninvasive blood pressure were recorded and compared 15 minutes before and 15, 30 and 45 minutes after drug administration. ResultsDogs administered MT had higher sedation scores than dogs administered M at 30 and 45 minutes after drug administration (p < 0.05). Times to ataxia, impaired walking, head drop and sternal recumbency were not different between the treatments. Time to lateral recumbency was longer in M than in MT (21.1 ± 1.0 versus 17.6 ± 0.7 minutes, respectively; p < 0.05). Time to standing was longer in MT than in M (67.9 ± 1.4 versus 54.5 ± 1.9 minutes, respectively; p < 0.001). Measured physiological variables did not differ between the treatments, with the exception of Pe′CO2, which was higher in MT than in M at all post-treatment evaluation times (p < 0.001). Conclusions and clinical relevanceTramadol combined with medetomidine resulted in greater sedation scores (deeper sedation) than medetomidine alone in dogs, and minimal adverse changes in the physiologic variables were measured.

Low velocity impact performance of curved steel-concrete-steel sandwich shells with bolt connectors

Abstract The low velocity impact performance of curved steel-concrete-steel (CSCS) sandwich shells with bolt connectors subjected to a hemi-spherical head drop hammer was investigated in this paper. Experimental results including impact force history, displacement history and permanent deformation were analyzed to reveal the influences of concrete core and steel plate thickness as well as shear connectors’ spacing on the impact performances of CSCS shells. The impact process consisted of three stages, i.e., inertial stage, loading stage and unloading stage. Meanwhile, three failure types were observed from the nine specimens subjected to impact load. They were plastic deformation of steel plate without fracture (Failure type I), fracture of steel plate (Failure type II) and penetration of steel plate (Failure type III). The presence of bolt connectors was proven to be an effective way to prevent the detachment of steel plates from concrete core. Moreover, finite element (FE) method was used to simulate the CSCS shells subjected to impact load. The accuracy of the FE model was verified by comparing the impact load history, displacement history and failure type from FE simulations with test results. It turned out that concrete core was the main part to dissipate impact energy, followed by top steel plate and bottom steel plate.

Investigations on the effect of tip clearance gap and inducer on the transport of air-water two-phase flow by centrifugal pumps

This study presents numerical and experimental investigations on air-water flows in a centrifugal pump. The objectives are to examine the accuracy of common numerical models, and to explain the influence of installing an inducer or increasing the tip clearance gap on the performance. 3D transient simulations were performed using the Volume of Fluid (VOF) method for two-phase modeling, and the k-ω SST model for turbulence modeling. The simulations agrees well with the experiments. However, the sudden head drop occurring at 5% gas content could not be predicted. Overall, the averaged relative errors between the simulations and the experiments for part-load, optimal, and overload conditions amount to 4%, 10% and 45%, respectively. The use of the inducer or increasing the gap leads to improvements in performance and phase mixing. Finally, bubble size distributions were analyzed using shadowgraphy, confirming that the inducer and the increased gap provide finer bubbles with narrower distributions.