Tail Pressure Research Articles

Variational principle for topological tail pressures with sub-additive upper semi-continuous potentials

ABSTRACTThe topological tail pressure and the conditional pressure are defined for sub-additive upper semi-continuous potentials via separated subsets and refining sequences of partitions in topological dynamical systems with finite topological entropy respectively. By proving the equivalence of the topological tail pressure and the conditional pressure with respect to the refining sequence of essential partitions, we present a variational principle for the topological tail pressure without any additional assumptions. The properties of the topological tail pressure including the power rule, the product rule and the natural extension are also discussed.

Pharmacological evidence for the folk use of Nefang: antipyretic, anti-inflammatory and antinociceptive activities of its constituent plants.

BackgroundNefang is a polyherbal anti-malarial composed of Mangifera indica (MiB and MiL; bark and leaf), Psidium guajava (Pg), Carica papaya (Cp), Cymbopogon citratus (Cc), Citrus sinensis (Cs) and Ocimum gratissimum (Og) (leaves). Previous studies have demonstrated its in vitro and in vivo antiplasmodial activities, antioxidant properties and safety profile. This study aimed at evaluating the antipyretic, anti-inflammatory and antinociceptive activities of the constituent plants of Nefang which are relevant to the symptomatic treatment of malaria fever.MethodsAntipyretic activities were determined by the D-Amphetamine induced pyrexia and Brewer’s Yeast induced hyperpyrexia methods. Anti-inflammatory activities were investigated using the carrageenan-induced rat paw edema method. Antinociceptive activities were determined by mechanical nociception in the tail pressure and thermal nociception in the radiant heat tail flick and hot plate methods. Data was analysed using the one way ANOVA followed by Neuman-Keuls multiple comparison test.ResultsBest percentage inhibition of induced pyrexia (amphetamine/brewer’s yeast; p < 0.05) was exhibited by Cc (95/97) followed by Og (85/94), MiL (90/89), MiB (88/84) and Cs (82/89). Cc and Og exhibited comparable activities to paracetamol (100/95).Anti-inflammatory studies revealed paw edema inhibition (%) as follows (p < 0.05): Indomethacin (47), MiL (40), Cp (30), MiB (28) and Og (22), suggesting best activity by MiL.Antinociceptive studies revealed significant (p < 0.01) pain inhibition (%) as follows: Paracetamol (97), Og (113), MiL (108), Pg (84) and MiB (88). Og and MiL exhibited the best activities.ConclusionThe results obtained suggest that the constituent plants possess biologically active compounds with antipyretic, anti-inflammatory and antinociceptive activities. These activities are essential in the symptomatic treatment of malaria fever, thereby justifying the folk use of Nefang. This would be useful in its subsequent development for clinical application.

Biomimetic Investigation of Intrabolus Pressure Signatures by a Peristaltic Swallowing Robot

The relationships among bolus formulation, engineering rheometric quantities, and peristaltic transport effects are examined in this paper. Investigation of a series of synthetic bolus materials and swallowing strategies is conducted using a novel peristaltic swallowing robot inspired by esophageal swallowing, which manifests as a benchtop rheological instrument. To determine the validity of biomimetic swallowing, manometry, a clinical technique for capturing swallowing pressure profiles is used to establish congruence between the robotic findings and those of a clinical nature. To determine the contribution of the bolus and swallowing strategy to the intraluminal pressure signature (ILPS), three parameters were varied: peristaltic wave velocity (20, 30, 40 mm $\mathrm{s}^{-1}$ ), wavefront length (40, 50, and 60 mm) and starch thickener (Nutulis, Nutricia) concentration (25, 50, 75, 100, and 150 g $\mathrm{L}^{-1}$ ) were investigated. Wave velocity and starch-based bolus formulation concentration were found to exhibit the most profound changes in the intrabolus pressure signatures. The highest bolus tail pressure gradient of 0.33 kPa $\mathrm{mm}^{-1}$ was achieved with a 150 g $\mathrm{L}^{-1}$ bolus formulation being transported at 40 mm $\mathrm{s}^{-1}$ with a wavefront length of 60 mm. In each dimension, the relationship between the parameters and features of the manometric pressure signature are found to be nonlinear owing to the shear-thinning, non-Newtonian nature of the model bolus fluid. The robotic ILPSs are synonymous with those of a clinical nature, suggesting that the swallowing robot has merit as a novel, biologically inspired, bolus investigation tool external to the human body.

High-dose pentazocine antagonizes the antinociception induced by high-dose morphine.

To investigate the effects of high doses of pentazocine on antinociception induced by a high dose of morphine and the role of the kappa-opioid receptors (KORs) in these effects in mice. Sixty-six C57BL/6J mice were pretreated with a KOR antagonist, nor-binaltorphimine (nor-BNI) (10mg·kg(-1)), or a normal saline placebo. All the mice received a subcutaneous injection of morphine (10mg·kg(-1)) 120min later and different doses of pentazocine (3, 10, 30, 56, 100mg·kg(-1)) or a normal saline placebo. A tail pressure test, hot plate test and tail flick test were performed before and at 30, 60, 90 and 120min after the injection of morphine. The tail pressure test, hot plate test and tail flick test showed that pentazocine at doses of 10 to 100mg·kg(-1), but not at 3mg·kg(-1), had significant antagonizing effects on the antinociception induced by high-dose morphine to mechanical and thermal pain, and nor-BNI did not affect antinociception in combination with pentazocine at 10 to 100mg·kg(-1) and morphine at 10mg·kg(-1). High-doses of pentazocine antagonize the antinociception induced by a high-dose of morphine in a dose-dependent manner, and this antagonistic effect is not associated with the activation of KORs.

Drag Reduction on the 35° Slant Angle Ahmed Reference Body Using Flaps

Based on computational fluid dynamics numerical simulation methods, this article studied the changes of resistance characteristics and tail pressure distribution on the 35° slant angle Ahmed model after installing the rear flaps. The results show that the appropriate size and reasonable arrangement of flaps can make the model tail separated airflow attach on the flap and the flap trailing edge separate again, narrow the tail separation zones, improve the model tail pressure, reduce the pressure difference on the forepart and rear model,lower the model resistance, then causing the drag reduction effect. The study found that the best drag reduction effect is to use 50 mm high flap, decorate in the rear bevel edge from Ahmed model 15 mm, the largest model resistance can be reduced by 5.37%.

Research on Underwater Vehicle and Tail Gas Mass Coupling Process

Rayleigh equation was applied to establish the model of the underwater vehicle tail gas mass developing process. The interrelationship of tail gas mass radius and pressure of was analyzed. The interaction equation between tail gas mass change and vehicle motion parameters was studied by coupling equation of gas mass and vehicle motion. The result shows that the simulation result agree with experimental results well, and show that the change of environment pressure with different work situations. The bigger initial pressure is, the longer oscillation period of vehicle tail pressure is. The bigger initial pressure is, the bigger initial acceleration is, but the acceleration is distinctly attenuate with time.

Assessment of morphine-induced hyperalgesia and analgesic tolerance in mice using thermal and mechanical nociceptive modalities.

Opioid-induced hyperalgesia and tolerance severely impact the clinical efficacy of opiates as pain relievers in animals and humans. The molecular mechanisms underlying both phenomena are not well understood and their elucidation should benefit from the study of animal models and from the design of appropriate experimental protocols. We describe here a methodological approach for inducing, recording and quantifying morphine-induced hyperalgesia as well as for evidencing analgesic tolerance, using the tail-immersion and tail pressure tests in wild-type mice. As shown in the video, the protocol is divided into five sequential steps. Handling and habituation phases allow a safe determination of the basal nociceptive response of the animals. Chronic morphine administration induces significant hyperalgesia as shown by an increase in both thermal and mechanical sensitivity, whereas the comparison of analgesia time-courses after acute or repeated morphine treatment clearly indicates the development of tolerance manifested by a decline in analgesic response amplitude. This protocol may be similarly adapted to genetically modified mice in order to evaluate the role of individual genes in the modulation of nociception and morphine analgesia. It also provides a model system to investigate the effectiveness of potential therapeutic agents to improve opiate analgesic efficacy.

Assessment of Morphine-induced Hyperalgesia and Analgesic Tolerance in Mice Using Thermal and Mechanical Nociceptive Modalities

Opioid-induced hyperalgesia and tolerance severely impact the clinical efficacy of opiates as pain relievers in animals and humans. The molecular mechanisms underlying both phenomena are not well understood and their elucidation should benefit from the study of animal models and from the design of appropriate experimental protocols. We describe here a methodological approach for inducing, recording and quantifying morphine-induced hyperalgesia as well as for evidencing analgesic tolerance, using the tail-immersion and tail pressure tests in wild-type mice. As shown in the video, the protocol is divided into five sequential steps. Handling and habituation phases allow a safe determination of the basal nociceptive response of the animals. Chronic morphine administration induces significant hyperalgesia as shown by an increase in both thermal and mechanical sensitivity, whereas the comparison of analgesia time-courses after acute or repeated morphine treatment clearly indicates the development of tolerance manifested by a decline in analgesic response amplitude. This protocol may be similarly adapted to genetically modified mice in order to evaluate the role of individual genes in the modulation of nociception and morphine analgesia. It also provides a model system to investigate the effectiveness of potential therapeutic agents to improve opiate analgesic efficacy.

The Contact Properties of Water Lubricated Rubber Stern Bearings after the Differentiation of Rubber Bush Hardness

With consideration to the manufacturing process, the rubber hardness of traditional rubber stern bearing is unified. However, due to the cantilever effect of propellers, the pressure distribution on traditional rubber stern bearings is uneven. In most cases, the tail pressure is higher than that in other locations. This affects the overall performance of stern bearings. Aiming at the problem, this paper reforms the rubber hardness of traditional rubber stern bearings and divides the bearing bush into different categories. Through computation and analysis, a reasonable length of each region and rubber hardness is established. With the help from finite element softwares, the finite element model of shaft -stern bearing is constructed. The Mooney-Rivlin model is then used to simulate rubber materials, and with the contact element analyzed, the contact relation is built between the shaft and stern bearing. The pressure distribution on the traditional rubber stern bearing and the improved one is calculated and compared, which reveals that the maximum contact stress is reduced by 25.6%, and the contact region is increased by 5.8°. Overall, the proposed method significantly improves the contact properties of stern bearings.

Application of the FUN3D Solver to the 4th AIAA Drag Prediction Workshop

FUN3D Navier–Stokes solutions were computed for the 4th AIAA Drag Prediction Workshop grid-convergence study, downwash study, and Reynolds-number study on a set of node-based mixed-element grids. All of the baseline tetrahedral grids were generated with the VGRID (developmental) advancing-layer and advancing-front grid-generation software package following the gridding guidelines developed for the workshop. With maximum grid sizes exceeding 100 million nodes, the grid-convergence study was particularly challenging for the node-based unstructured grid generators and flow solvers. At the time of the workshop, the super-fine grid with 105 million nodes and 600 million tetrahedral elements was the largest grid known to have been generated using VGRID. FUN3D Version 11.0 has a completely new pre- and postprocessing paradigm that has been incorporated directly into the solver and functions entirely in a parallel, distributed-memory environment. This feature allowed for practical preprocessing and solution times on the largest unstructured-grid size requested for the workshop. For the constant-lift grid-convergence case, the convergence of total drag is approximately second-order on the finest three grids. The variation in total drag between the finest two grids is only two counts. At the finest grid levels, only small variations in wing and tail pressure distributions are seen with grid refinement. Similarly, a small wing side-of-body separation also shows little variation at the finest grid levels. Overall, the FUN3D results compare well with the structured-grid code CFL3D. For the grid-convergence case, the FUN3D total and component forces/moments are within one standard deviation of the workshop core solution medians and are very close to the median values especially at the finest grid levels. The FUN3D downwash study and Reynolds-number study results also compare well with the range of results shown in the workshop presentations.

Changes of eNOS and Ser1179 activity in myocardial tissue of hypertensive rats at different stages

Objective To observe endothelial nitric oxide synthase (eNOS) protein expression in myocardial tissue of hypertension rats at different periods and its related regulation with loci Ser1179 phosphorylation levels,NOS activity and NO yield changes,to explore the relationship between blood pressure and eNOS in myocardial tissue.Methods 24 SD rats were randomly divided into four groups,control group 2 w,4 w and hypertension group 2 w,4 w,6 in each group,producing two-kideny two-clip renovascular hypertensive rats model (2k2c RH model).Blood pressure of rats was detected by rat tail pressure measuring method,eNOS,P-NOS (P-Ser1179) protein expression in myocardial tissue by Western Blot,NO in myocardial tissues by nitrate reductase method.Result Compared with the control group,eNOS protein expression and Ser1179 phosphorylation level in myocardial tissue of RH rats didn't obviously change after 2 weeks (P ＞ 0.05),but increased significantly after 4 weeks (P ＜ 0.01).Conclusions 2k2c RH rats myocardial tissue exists eNOS changes in protein expression and activity,has an important compensatory eNOS adjust action,which may be related to stimulation of Ser1179 phosphorylation level and NOS activity caused by increased blood pressure. Key words: Nitric oxide synthase; Phosphorylation; Renovascular hypertension

Heavy ion effects on substorm loading and unloading in the Earth's magnetotail

We have performed a statistical study investigating how substorm triggering and unloading is affected by the heavy ion content of the magnetotail plasma sheet. During the substorm growth phase, magnetic flux is accumulated in the tail lobes until the magnetotail reaches an unstable state. A near‐Earth neutral line then forms, and this excess flux is reconnected. The increased lobe magnetic flux during the substorm growth phase increases the magnetopause flaring angle. As a result, a greater fraction of the solar‐wind dynamic pressure is observed in the tail lobes and plasma sheet. Therefore, the increase and decrease of the lobe magnetic flux can be monitored by observing the increase and decrease in the magnetotail pressure. Using Cluster data from 2001 to 2004, we have determined how the maximum pressure (or flaring angle) and the rate of change of pressure (or flaring angle) during substorms depend on the O+ content of the plasma sheet. In addition, we have estimated the maximum magnetic flux, and rate of change of the magnetic flux. Our results show that both the maximum tail pressure and the rate of change in the pressure are positively correlated with the amount of O+ in the plasma sheet. When the measurements are normalized to account for the external solar‐wind pressure and the different Cluster locations in the tail, the maximum accumulated flux and the unloading rate still correlate positively with the O+ density and O+/H+ ratio. This suggests that the additional O+ makes it more difficult to trigger the substorm onset, but once it is triggered, the unloading is faster. This could either indicate that the presence of O+ increases the reconnection rate, or that it initiates reconnection over a broader width of the tail.

The calculation of train slipstreams using large-eddy simulation

High-speed trains push air to the front, sides and over the top to form a train slipstream. The extension of the slipstream to the side, top and wake flow depends on train speed, train shape, ambient conditions and the environment in which the train operates. In this paper, the slipstream and wake flow of a 1/20th scale model of a simplified five-coach ICE2-shape train running in two different environments; in open air and when passing a platform, were obtained using large-eddy simulation (LES). The flow Reynolds number was taken to be 300,000; based on the speed and height of the train. The effect of the platform height on the train slipstream was investigated by performing simulations on a platform of different heights: 20, 60, 90 cm. To investigate the effect of mesh resolution on the results, two different computations were performed for the case of the flow around the train running in the open air using a different number of mesh nodes; a fine mesh consisting of 18,000,000 nodes and a coarse mesh consisting of 12,000,000 nodes. The results of the coarse mesh simulation were deemed to be comparable to those from the fine mesh simulation. The LES results were also compared with full-scale data and a good agreement obtained. A number of different flow regions were observed in the train slipstream: upstream region, nose region, boundary layer region, inter-carriage gap region, tail region and wake region. Localized velocity peaks were obtained near the nose of the train and in the near wake region. Coherent structures were formed at the nose, roof and inter-carriage gaps of the train. These structures spread in the slipstream and extend a long distance behind the train in the far wake flow. The maximum slipstream turbulent intensity was found in the near wake flow. The results showed that there is a significant effect of the platform height on the slipstream velocity and nose and tail pressure pulses. However, there is only a minor effect of the platform height on the static pressure along the body of the train compared with that on the nose and tail pressure pulses. In general, the slipstream velocity in the lower region of a train running in the open air was found to be larger than that around a train passing a platform. This has been related to the effect of the underbody complexities of the train.

Research on the base cavity of a sub-launched projectile

The finite volume method based on a multiphase model is adopted to solve the Reynolds-Averaged Navier-Stokes (RANS) equations, which takes into account the effects of fluid compressibility, viscosity, gravity, medium mixture and energy transfer of water and combustion gas. The program Fluent User Define Function (UDF) module combined with the dynamic mesh method is employed to simulate the coupling flow field of combustion gas, water field and trajectory of projectile. The results show that the volume of gas cavity at the bottom of projectile and tail pressure will fluctuate after bottom of the projectile leaving the launch tube. The cause of the fluctuation is analyzed and its effects on the trajectory of projectile are presented. The numerical and experimental results agree well with each other.

The altered pelvic nursing hanger applied in pelvic fractures Patients with clinical nursing observation

Objective To study the pelvic fracture patient application altered pelvic nursing hanger clinical nursing methods and effects.Methods random will 86 cases in pelvic fracture patients into sta 42 cases,the comparison to 44 cases,and the application of pelvic nursing hanger frame group,give routine observation nursing care.Results:two groups of patients to pain feelings degree,pelvic ring shift condition,the treatment of recovery rate,Group than in the control groups,a statistically significant difference (P＜0.05).Conclusion the pelvis nursing hanger can according to the human body mechanics principle,changed the stress of the direction and pelvic structural support,stabilize effectively prevent fractures ring.Zhe tail pressure ulcers,solve bed defecate is difficult and clean,reduce pain and to improve the quality of nursing,flexible operation is handy,save manpower resources,etc. Key words: Pelvic; Fractures; Nursing hanger

Tail pressure and the tail entropy function

AbstractBurguet [A direct proof of the tail variational principle and its extension to maps. Ergod. Th. &amp; Dynam. Sys.29 (2009), 357–369] presented a direct proof of the variational principle of tail entropy and extended Downarowicz’s results to a non-invertible case. This paper defines and discusses tail pressure, which is an extension of tail entropy for continuous transformations. This study reveals analogs of many known results of topological pressure. Specifically, a variational principle is provided and some applications of tail pressure, such as the investigation of invariant measures and equilibrium states, are also obtained.

Pentazocine-Induced Antinociception Is Mediated Mainly by μ-Opioid Receptors and Compromised by κ-Opioid Receptors in Mice

Pentazocine is a widely used mixed agonist-antagonist opioid. Previous animal studies have demonstrated that pentazocine-induced antinociception displayed a ceiling effect characterized by biphasic dose response with a increasing and then descending analgesia like a bell-shaped curve. This study attempted to clarify the mechanisms underlying such dose-response relationships. ddY and C57BL/6J mice received subcutaneous injection of saline or pentazocine (3, 10, 30, 56, or 100 mg · kg(-1)), at 120 min after subcutaneous injection of saline, a μ-opioid receptor antagonist clocinnamox mesylate (C-CAM) (5 mg · kg(-1)), a κ-opioid receptor antagonist nor-binaltorphimine (nor-BNI) (10 mg · kg(-1)), or the combination of C-CAM and nor-BNI. The antinociceptive effects of pentazocine were evaluated using tail pressure, hot plate, tail flick, and acetic acid writhing tests. Without pretreatment with an opioid receptor antagonist, the antinociceptive effects of pentazocine exhibited biphasic bell-shaped dose-response curves peaking at 30 mg · kg(-1). C-CAM completely and partly antagonized the antinociception induced by pentazocine at low (3-30 mg · kg(-1)) and high (56-100 mg · kg(-1)) doses, respectively. nor-BNI enhanced the antinociception by pentazocine at high doses and turned the later descending portion of the biphasic dose-response curves into a sigmoid curve. The combination of C-CAM and nor-BNI completely abolished the antinociception by pentazocine at all doses. Our results suggest pentazocine produces antinociception primarily via activation of μ-opioid receptors, but at high doses, this μ-opioid receptor-mediated antinociception is antagonized by concomitant activation of κ-opioid receptors. This provides the first reasonable hypothesis to explain the ceiling effects of pentazocine analgesia characterized by a biphasic dose response.

On the role of a central adrenergic mechanism in morphine analgesic action.

Abstract The influence of drugs interfering with brain monoamine metabolism on morphine analgesia of rats was estimated by the tail pressure method. Central adrenergic stimulation produced by apomorphine, cocaine, pyrogallol or amphetamine led to stereotyped behaviour and elevation of the pain threshold. Lower doses of these drugs potentiated morphine analgesic action. Reserpine, iproniazid and disulfiram weakened morphine analgesic action. α-Methyldopa increased morphine action and (±)-tryptophan did not influence it significantly.

Potentiation of dermorphin-induced antinociception by peptidase inhibitors.

We have investigated the effect of amastatin, an aminopeptidase inhibitor, and captopril, an angiotensin converting enzyme inhibitor, on the antinociceptive activity induced by intracerebroventricular administration of dermorphin, a heptapeptide. In addition, the potency of dermorphin was compared with that of one of its metabolites, N-terminal tetrapeptide (Tyr-D-Ala-Phe-Gly), by using the tail pressure test. The antinociceptive activity induced by dermorphin was not potentiated by simultaneous administration of amastatin or captopril. However, there was potentiation when dermorphin was combined with both peptidase inhibitors. Moreover, the N-terminal tetrapeptide was 84 times less potent than its parent heptapeptide when administered intracerebroventricularly. The results suggest that the cleavage of Tyr1-D-Ala2 and Gly4-Tyr5 bonds by brain endopeptidase modulates dermorphin-induced antinociceptive activity.

Oblique normal faulting along the northern edge of the Majella Anticline, central Italy: Inferences on hydrocarbon migration and accumulation

Along the northern edge of the Majella anticline, in a large quarry originally excavated by ancient Romans, we studied the deformation mechanisms and internal architectures of faults characterized by both normal and lateral components of slip. These oblique normal faults, which crosscut Miocene carbonate grainstones, are associated with hydrocarbons in the form of tar. Within the faults, tar is present in the breccia of the fault cores, as well as in the surrounding fractured and faulted damage zones. Outside of them, tar is found within the porous carbonate beds flanking the oblique normal faults. We propose a conceptual model of fault nucleation and development. In this model, incipient faulting was characterized by shearing of the pre-existing pressure solution seams and formation of two main sets of tail pressure solution seams. With ongoing faulting, exhumation, and growth of the Majella anticline, the main deformation mechanism switched to predominant opening-mode failure in the form of tail joints and veins within the evolving oblique normal faults. This processes allowed the linkage of isolated slip surfaces across contiguous carbonate beds, and the development of isolated pods of fragmented rocks along the evolving faults. Brecciation and cataclasis localized only along the main slip surfaces of the oblique normal faults, forming a zone of intense deformation, the fault core, surrounded by less-deformed fractured, faulted and fragmented carbonates of the damage zone. Tar distribution was used as a proxy for fault and fracture permeability. Well-developed oblique normal faults, as a whole, form combined barrier-conduit structures to fluid flow. The cataclastic rocks, if continuous along the fault cores, form seals for cross-fault fluid flow, whereas the fault breccia and the surrounding carbonate damage zones act as conduits to fluid flow. Less-evolved oblique normal faults may form either distributed or localized conduits for fluid flow, depending on the presence (distributed) or absence (isolated) of fragmented carbonates around the conductive slip surfaces. Due to their orientation, these faults enhance the overall fault parallel fluid flow, which is thus prominent in the damage zones of the larger faults. The fundamental structural elements with greater tar content are sub-parallel to the current σ hmax of central Italy, reflecting the possible control exerted by the stress state on the overall fault and fracture permeability. At a larger scale, as suggested by the structural location of the study quarry, hydrocarbons are channeled primarily within the releasing jogs of interacting oblique normal faults.