Up-down Method Research Articles

Machinability features in micro die-sinking electrical discharge machining

To manufacturing the micro parts, diverse methods have been studied and reported. Electric discharge machining (EDM) is adopted to overcome the limitations of conventional cutting methods. In this paper, a die-sinking EDM plan with the design of experiment is set up to analyse the characteristics of the die-sinking EDM. Variable factors are voltage, capacity, machining method and polarity. The analysis of variance on experimental data shows what influence can be brought after the change of the variable factors into electrode wears, workpiece edge length and surface roughness. The tendency in each condition of die-sinking EDM is studied by average response value. The results show that: 1) low discharge voltage and high capacity can enhance the precision of machined edge shape, 2) a DC-straight polarity method has an advantage over a DC-reverse polarity method, 3) an up-down method outperforms a slow down method.

The lowest effective intracuff pressure of the esophagus obstruction tube to prevent reflux of gastric contents: a study on rabbits

To determine the lowest effective cuff pressure of the esophageal obstruction tube to prevent reflux of gastric contents in rabbits. Twenty-two New Zealand white rabbits (2.0-2.5 kg) were anesthetized. An esophageal obstruction tube, an esophageal observation tube, and a gastric tube were inserted into the esophagus and stomach, respectively. Normal saline containing methylene blue was injected into the stomach for an animal model of gastric contents reflux. Possible saline reflux was observed through the esophageal observation tube. It was considered "regurgitation" when the saline flowed out, and "no regurgitation" when the saline did not. When a "regurgitation" result was obtained in a particular rabbit, the intracuff pressure was increased by 10 cm H(2)O in the following rabbit and vice versa. The trial was not terminated until six crossover points were observed from "no regurgitation" to "regurgitation." A probit regression model was used to analyze the effective intracuff pressure of the esophagus obstruction tube after 50 % and 95 % of the rabbits showed no reflux. The lowest effective intracuff pressure to prevent reflux of gastric contents in 50 % of rabbits from the Dixon up-down method was 61.67 ± 8.16 cm H(2)O. The intracuff pressures at which there was 50 % and 95 % probability of lack of gastric contents reflux from a probit regression model were 61.95 and 74.39 cm H(2)O, respectively. The insertion of an esophageal obstruction tube before endotracheal intubation can be an acceptable method for preventing the reflux of gastric contents in most rabbits under light anesthesia.

Determination of the Effective Dose of Pregabalin on Human Experimental Pain Using the Sequential Up-Down Method

The intradermal capsaicin pain model has been used to evaluate analgesic effects of a variety of drugs. Using the sequential up-down method, we examined the analgesic effects of pregabalin on intradermal capsaicin pain. Using a double-blind, placebo-controlled, crossover study, healthy adult men were randomized to oral pregabalin or placebo on the first visit and returned for the opposite treatment after a washout period. Dosing was set by the Dixon sequential up-down method; that is, a greater or less than 30% reduction in capsaicin pain decreased or increased the dose, respectively, by a fixed interval for the next subject. The median effective dose (ED50) was derived once 7 changes in dose direction occurred. Secondary outcome measures included secondary hyperalgesia and tactile and thermal allodynia, and their respective areas (cm2). Thirteen subjects were required to derive the pregabalin ED50: 252 mg (95% confidence interval 194, 310 mg). Most common side effects were drowsiness (46%), euphoria (31%), and dizziness (7%). Those with ≥30% pain reduction as compared to placebo also had similar reductions in secondary outcome measures. The intradermal capsaicin pain model can be used to efficiently derive the pregabalin ED50, but well-powered dose-response curve studies are needed for comparison and validation. PerspectiveUsing the Dixon sequential up-down method, the ED50 of pregabalin on intradermal capsaicin induced pain was successfully calculated (252 mg) using only 13 subjects.

The fentanyl concentration required for immobility under propofol anesthesia is reduced by pre-treatment with flurbiprofen axetil

We hypothesized that nonsteroidal anti-inflammatory drugs decrease the plasma fentanyl concentration required to produce immobility in 50% of patients in response to skin incision (Cp50incision) compared with placebo under target-controlled infusion (TCI) propofol anesthesia. Sixty-two unpremedicated patients scheduled to undergo gynecologic laparoscopy were randomly assigned to receive placebo (control group) or flurbiprofen axetil 1 mg·kg(-1) (flurbiprofen group) preoperatively. General anesthesia was induced with fentanyl and propofol, and intubation was performed after succinylcholine 1 mg·kg(-1). Propofol was administered via a target-controlled infusion (TCI) system (Diprifusor™) set at an effect-site concentration of 5 μg·mL(-1). Fentanyl was given by a TCI system using the STANPUMP software (Schafer model). The concentration for the first patient was set at 3 ng·mL(-1) and modified in each group according to the up-down method. Skin incision was performed after more than ten minutes equilibration time. Serum fentanyl concentration, bispectral index (BIS), and hemodynamic parameters were measured two minutes before and after skin incision. The Cp50incision of fentanyl was derived from the mean of the crossovers (i.e., the serum fentanyl concentrations of successive participants who responded and those who did not or vice versa). Ten and 11 independent crossover pairs were collected in the control and flurbiprofen groups, respectively, representing 42 of 62 enrolled patients. The mean (SD) fentanyl Cp50incision was less in the flurbiprofen group [0.84 (0.63) ng·mL(-1)] than in the control group [1.65 (1.15) ng·mL(-1)]; P = 0.007; however, there were no differences in BIS, blood pressure, or heart rate, between groups. Preoperative flurbiprofen axetil decreased the Cp50incision of fentanyl by 49% during propofol anesthesia without changing the BIS or hemodynamic variables.

Minimum alveolar concentration of desflurane with caudal analgesia for laryngeal mask airway removal in anesthetized children

Regional blocks have been shown to decrease the requirement of anesthetic agents. This study was conducted to determine the optimal endtidal concentrations of desflurane for removal of Laryngeal mask airway in children in presence of caudal block. Twenty-two children of ASA status I between the age group of 2-10 year undergoing infraumbilical surgery were enrolled in the study. General anesthesia was induced with sevoflurane and oxygen given via mask and laryngeal mask airway inserted. Caudal injection of bupivacaine 0.25%, 1 ml·kg(-1) was administered according to Armitage regimen. Desflurane was used for maintenance of anesthesia. Predecided endtidal concentration of desflurane was maintained for 10 min at the end of surgery and laryngeal mask airway removed. Target concentration in the next patient was thereafter determined by the Dixon up-down method (with 0.5% as a step size). 5% endtidal concentration was kept as the starting concentration. If removal of laryngeal mask airway was not associated with any coughing, teeth clenching, gross purposeful movement, breath holding or laryngospasm, during or within 1 min after removal, it was considered as successful. In the presence of caudal analgesia, endtidal concentration of desflurane required for successful laryngeal mask airway removal in 50% (ED50) children was 3.39 ± 0.38% by Dixon's method. Laryngeal mask airway can be successfully removed in 50% of anesthetized children without coughing, moving, or any other airway complications at an endtidal desflurane concentration of 3.4% in the presence of caudal analgesia.

On the limitations of fixed‐step‐size adaptive methods with response confidence

The family of (non-parametric, fixed-step-size) adaptive methods, also known as 'up-down' or 'staircase' methods, has been used extensively in psychophysical studies for threshold estimation. Extensions of adaptive methods to non-binary responses have also been proposed. An example is the three-category weighted up-down (WUD) method (Kaernbach, 2001) and its four-category extension (Klein, 2001). Such an extension, however, is somewhat restricted, and in this paper we discuss its limitations. To facilitate the discussion, we characterize the extension of WUD by an algorithm that incorporates response confidence into a family of adaptive methods. This algorithm can also be applied to two other adaptive methods, namely Derman's up-down method and the biased-coin design, which are suitable for estimating any threshold quantiles. We then discuss via simulations of the above three methods the limitations of the algorithm. To illustrate, we conduct a small scale of experiment using the extended WUD under different response confidence formats to evaluate the consistency of threshold estimation.

REPEATED EXPOSURE OF GOLDFISH (CARASSIUS AURATUS) TO TRICAINE METHANESULFONATE (MS-222)

Goldfish that have been repeatedly exposed to tricaine methanesulfonate (MS-222) require greater concentration of the drug to attain equivalent planes of anesthesia, but the mechanism for this increased anesthetic need is unknown. Minimum anesthetic concentration (MAC) is a commonly used method with which to compare anesthetics. It was hypothesized that fish exposed to MS-222 daily would have an increased MAC. It was also hypothesized that fish exposed daily to MS-222 would develop histomorphologic changes to their gills to explain the increasing demand. Forty-nine Serasa comet goldfish were enrolled and were divided into three populations (n = 15, n = 15, and n = 19). In trial 1, using an up-down method, MAC was determined daily after 4 min of exposure to MS-222 for which the starting concentration was 160 mg/L. In trial 2, MAC was determined following 2 min of exposure to MS-222 for which the starting concentration was 260 mg/L. In trial 3, four naive fish were euthanatized and gills collected for histology and electron microscopy (EM). The remaining fish were exposed to MS-222 daily for 4 wk. Four fish were euthanatized and their gills submitted for similar examination at 2 wk and 4 wk. MAC for fish exposed to MS-222 for 4 min increased from 120 to 160 mg/L. The regression line had a slope of 1.51 +/- 0.26 (R2 = 0.65; P < 0.0001). MAC for fish exposed to MS-222 for 2 min increased from 210 pmm to 220 mg/L; the regression line had a slope of 0.52 +/- 0.38 (R2 = 0.12; P = 0.2). Histologic and EM examination of gills did not show morphologic changes indicative of a reaction to MS-222. Goldfish in this study had an increased requirement for MS-222 following daily exposure for 4 min but not following daily exposure for 2 min at a higher concentration. The cause of this increased anesthetic need is not related to morphologic changes to the gills.

Lidocaine use in ultrasound-guided femoral nerve block: what is the minimum effective anaesthetic concentration (MEAC90)?

This study aimed to estimate the minimum effective anaesthetic concentrations of lidocaine required to block the femoral nerve under ultrasound (US) guidance in 90% (MEAC90) of patients. A minimum of 45 patients who had undergone knee arthroscopy were included in this observational study. All the patients received US-guided sciatic, obturator, and femoral nerve blocks. The femoral nerve block was performed using 15 ml of lidocaine. The lidocaine concentration given to a patient was determined by the response of the previous patient (a biased-coin design up-down sequential method). If a patient had a negative response, the lidocaine concentration was increased by 0.1% w/v in the next patient. If a patient had a positive response, the next patient was randomized to receive the same lidocaine concentration (with a probability of 0.89) or to receive a concentration 0.1% w/v less (with a probability of 0.11). A positive response was defined as complete sensory and motor block. The patients' responses were analysed to calculate the mean MEAC90. Fifty-two patients were required to complete the study; 45 had a positive response and seven had a negative response. The mean MEAC90 was estimated to be 0.93% w/v [95% confidence interval (CI), 0.8-1.03%]. Lidocaine 0.93% w/v was estimated to produce a successful block in 89% (95% CI, 78-100%) of patients. Perineural injection of 15 ml of lidocaine 0.93% w/v under US guidance could provide successful femoral nerve block in 90% of patients.

The l‐kynurenine–probenecid combination reduces neuropathic pain in rats

l-Kynurenine has antinociceptive effects in acute and inflammatory pain. This study determined the effect of l-kynurenine and its metabolite (kynurenic acid) on rats subjected to neuropathic pain. L5/L6 spinal nerve ligation induced tactile allodynia as measured with von Frey filaments using the up-down method. High-performance liquid chromatography and Western blot analysis determined kynurenic acid levels and expression of kynurenine amino transferase II (KAT II), respectively. l-Kynurenine (50-200 mg/kg, i.p.) or probenecid (100 mg/kg, i.p.) did not affect allodynia in neuropathic rats. In contrast, l-kynurenine (50-200 mg/kg, i.p.) in combination with probenecid (100 mg/kg, i.p.), an inhibitor of organic anion transport, reversed allodynia. Furthermore, intrathecal kynurenic acid (1-30 μg) reversed allodynia. Probenecid (100 mg/kg, i.p.) supplementation enhanced the maximal antiallodynic effect of intrathecal kynurenic acid (10 μg). Only the combined administration of l-kynurenine (200 mg/kg)/probenecid (100 mg/kg) increased the kynurenic acid concentration in cerebrospinal fluid. KAT II is expressed in dorsal root ganglia and dorsal spinal cord. KAT II expression was unchanged by the spinal nerve ligation or l-kynurenine/probenecid combination. The kynurenine/probenecid combination did not affect motor activity. l-Kynurenine produces its antiallodynic effect in the central nervous system through kynurenic acid. This effect may result from blockade of N-methyl-d-aspartate receptors. KAT II is expressed in dorsal root ganglion and dorsal spinal cord. Combined l-kynurenine and probenecid therapy has the potential to reduce neuropathic pain in humans.

Orthogonal Experimental Study on the Grinding-Hardened Layer’s Depth and its Uniformity of 45 Steel

Based on the orthogonal experiment of grinding-hardening machine, this paper studied the influence of depth of cut ap, table speed vw and grinding method gm on the grinding-hardened layer’s depth and its uniformity of 45 steel. The results show that, depth of cut ap is the significant factor affected the average value of grinding-hardened layer’s depth, but the influence of grinding conditions on the uniformity are very limited. In actual application, it should adopt ap=0.6mm, vw=0.4m/min and up-down grinding method to enhance the quality of grinding-hardened layer.

Dietary Supplementation with Docosahexanoic Acid (DHA) Improves RBC Flexibility and Reduces Cold Hypersensitivity in Mice with Sickle Cell Disease.

AbstractAbstract 2116Humans and mice with sickle cell disease (SCD) have RBC stiffness, multiorgan and vascular pathology, and complex pain syndromes. Omega-3 fatty acids, such as docosahexanoic acid (DHA), are essential fatty acids that have anti-inflammatory and anti-thrombotic activities. As dietary supplements, omega-3 fatty acids are beneficial in many cardiovascular diseases. Several studies demonstrate that dietary supplementation with omega-3 fatty acids results in increased incorporation of these fatty acids into the RBC membrane, which can influence RBC deformability. In this study, SCD mice were fed natural ingredient rodent diets supplemented with 3% DHA (DHA diet) or a control matched in total fat with a similar distribution of saturated, monounsaturated, and polyunsaturated fatty acids (CTRL diet). After 8 weeks of feeding, we examined the RBCs for: 1) deformability, as measured by ektacytometry; 2) stiffness, as measured by atomic force microscopy; 3) osmotic fragility, using a flow cytometric method; and 4) percent irreversibly sickled RBCs on peripheral blood smears. Consistent with other studies, RBCs from SCD mice fed Control diet exhibit low deformability by ektacytometry as compared to RBCs from wild-type mice (0.075 Max EI, SCD mice Control Diet, versus 0.285 Max EI, wild-type mice). Correspondingly, RBC stiffness, as measured by atomic force microscopy, is increased in SCD mice fed Control diet as compared to wild-type mice (1911 Pa, SCD mice Control Diet, versus 831 Pa, wild-type mice). In contrast, RBCs from SCD mice fed DHA diet had improved deformability (0.135 Max EI) compared to RBCs from SCD mice fed Control diet (p<0.02). Furthermore, RBCs from DHA diet-fed SCD mice had markedly decreased stiffness (798 Pa) to nearly normal levels compared to RBCs from Control diet-fed SCD mice (p<0.0001). In addition, RBCs from SCD mice fed DHA diet had decreased osmotic fragility as compared to RBCs from SCD mice fed Control diet (p<0.001). Examination of peripheral blood smears also revealed less irreversibly sickled RBCs in SCD mice fed DHA diet as compared to Control Diet (2.5% versus 4.1%, p<0.04). These results suggest that DHA supplementation has modified RBC membrane properties of SCD mice. Individuals with SCD as well as murine models of SCD display increased sensitivity to pain. Stiffened RBCs are thought to contribute to pain in SCD by stimulating vasoocclusive events. Importantly, a small-scale human SCD trial indicated that dietary supplementation with omega-3 fatty acids reduced pain episodes by almost 50% (Tomer, et al, 2001). Therefore, we measured sensitivity of SCD mice to mechanical and cold stimuli both prior to dietary feeding and after 8 weeks of feeding on Control or DHA diet. Mechanical hypersensitivity was assessed using von Frey filaments, with the paw withdrawal threshold assessed using the up-down method of Dixon (1980). Mechanical hypersensitivity thresholds are reduced in SCD mice (Hillery, et al, 2011), and were not altered by either the Control or DHA diet. Cold hypersensitivity was assessed using a 2-temperature choice assay and measuring the amount of time spent on the colder plate (23°C) versus the warmer plate (30°C). Similar to our previous findings, SCD mice exhibit hypersensitivity to cold. There was no change in pre- versus post-diet cold hypersensitivity in SCD mice fed Control diet. In contrast, post-diet cold hypersensitivity was improved compared to pre-diet cold hypersensitivity in SCD mice fed DHA diet (p<0.007). In summary, our findings indicate that DHA supplementation improves RBC flexibility, decreases osmotic fragility and irreversibly sickled cells, and reduces cold hypersensitivity in a murine model of SCD. The reduction in cold hypersensitivity may reflect the increased flexibility of the RBCs, making them less likely to cause vasoocclusive events that can activate inflammatory pain mechanisms. Additionally, resolvins D1 and D2, anti-inflammatory lipid mediators derived from DHA, inhibit the activity of the transient receptor potential vanilloid 1 (TRPV1) and ankyrin 1 (TRPA1) channels, which contribute importantly to inflammatory pain sensitivity to mechanical and thermal stimuli. Disclosures:Mickelson:Harlan Laboratories, Inc.: Employment. Stucky:Purdue Pharma: Research Funding. Hillery:Purdue Pharma: Research Funding; Bayer Pharmaceuticals: Consultancy.

Measurements of the just noticeable difference for reverberation time using a transformed up–down adaptive method

This investigation sought to measure the just noticeable difference (JND) for reverberation time (T30) using a rigorous psychophysical method, namely the transformed up-down adaptive method. In ISO 3382-1:2009, the JND for reverberation metrics is taken to be 5%, based on work by Seraphim (1958); however, others have suggested that the actual JND is higher. In this project, sound samples with varying T30 were auralized from impulse responses simulated in a realistically modeled performance space using ODEON. The model’s absorption coefficients were uniformly varied across all surfaces and frequencies to achieve the desired T30s. Three reference reverberation times were utilized (one, two, and three seconds), and eight T30 cases spaced at 4% intervals both above and below each of the three reference T30s were created. Auralizations using a 500 ms white noise burst were presented in a computer-based testing program running a three-interval one-up two-down forced choice method, presented in a sound booth over headphones with flat frequency response. The program randomly interleaved six staircase sequences, three of which ascended and three of which descended towards each reference T30. Results averaged across 30 participants will be presented. [Work supported by a UNL UCARE Grant and the ASA Robert W. Young Award.]

High-frequency auditory filter shape for the Atlantic bottlenose dolphin

High-frequency auditory filter shapes of an Atlantic bottlenose dolphin (Tursiops truncatus) were measured using a notched noise masking source centered on pure tone signals at frequencies of 40, 60, 80 and 100 kHz. A dolphin was trained to swim into a hoop station facing the noise/signal transducer located at a distance of 2 m. The dolphin's masked threshold was determined using an up-down staircase method as the width of the notched noise was randomly varied from 0, 0.2, 04, 0.6, and 0.8 times the test tone frequency. The masked threshold decreased as the width of the notched increased and less noise fell within the auditory filter associated with the test tone. The auditory filter shapes were approximated by fitting a roex (p,r(r)) function to the masked threshold results. A constant-Q value of 8.4 modeled the results within the frequency range of 40 to 100 kHz relatively well. However, between 60 and 100 kHz, the 3 dB bandwidth was relatively similar between 9.5 and 10 kHz, indicating a constant-bandwidth system in this frequency range The mean equivalent rectangular bandwidth calculated from the filter shape was approximately 16.0%, 17.0%, 13.6% and 11.3% of the tone frequencies of 40, 60, 80, and 100 kHz.

DEVELOPMENT OF A MINIMUM-ANESTHETIC-CONCENTRATION DEPRESSION MODEL TO STUDY THE EFFECTS OF VARIOUS ANALGESICS IN GOLDFISH (CARASSIUS AURATUS)

Teleost fish demonstrate the neurophysiologic capacity to experience pain and analgesia. A common model for assessing analgesic effect is the reduction of minimum anesthetic concentration (MAC). The present study adapted the model of MAC depression to evaluate the analgesic effects of morphine, butorphanol, medetomidine, and ketoprofen in goldfish (Carassius auratus). MAC was determined by an up-down method of sequential population sampling, anesthetizing fish with tricaine methanesulfonate (MS-222) in concentration increments of 10 parts per million (ppm), and using intramuscular needle insertion as a supramaximal noxious stimulus. Baseline MAC was determined in triplicate at the beginning (MACi) and conclusion (MACe) of the experiment (approximately 60 days). For drug trials, MAC was redetermined 1 hr after administration of morphine (10, 20, 40 mg/kg i.m.), butorphanol (0.1, 0.2, 0.4 mg/kg i.m.), medetomidine (0.01, 0.015, 0.025 mg/kg i.m.), ketoprofen (0.5, 1.0, 2.0 mg/kg i.m.), or saline control. Each drug/dose was tested in random order with a > 6-day washout period. MACi and MACf were 163 and 182 ppm, respectively, and were significantly different from each other (P = 0.02). All doses of morphine and ketoprofen decreased MAC below MACi. The highest dose of medetomidine decreased MAC below MACi. The lowest dose of butorphanol decreased MAC below MACi, but higher doses increased MAC above MACf. The authors conclude that MAC determination in fish using MS-222 was feasible and reproducible in the short term. The fact that MAC increased over time and/or exposure may limit the usefulness of MS-222 in MAC depression studies. Morphine and ketoprofen decrease anesthetic needs in goldfish and may provide analgesia.

Estimating Efficacy and Drug ED50's Using von Frey Thresholds: Impact of Weber's Law and Log Transformation

The use of von Frey filaments, originally developed by Maximilian von Frey, has become the cornerstone for assaying mechanical sensitivity in animal models and is widely used for human assessment. While there are certain limitations associated with their use that make comparisons between studies not straightforward at times, such as stimulus duration and testing frequency, von Frey filaments provide a good measurement of mechanosensation. Here we describe the application of von Frey filaments to testing in animal models, specifically with respect to determining changes in sensory thresholds in a pain state using the Dixon up-down method. In a literature survey, we found that up to 75% of reports using this method analyze the data with parametric statistical analysis and of those that used nonparametric analysis, none took into account that mechanical sensation is perceived on a logarithmic scale (Weber's Law) when calculating efficacy. Here we outline a more rigorous analysis for calculating efficacy and ED50's from von Frey data that incorporates Weber's Law. We show that this analysis makes statistical and biological sense and provide a specific example of how this change affects data analysis that brings results from animal models more in line with clinical observations. PerspectiveThis focus article argues that analyzing von Frey paw withdrawal threshold data obtained by using the Dixon up-down method without considering Weber's Law is inappropriate. An analysis method that incorporates how mechanical sensation is perceived and how its application brings results from animal models more in line with clinical data is presented.

Acute and Chronic Tactile Sensory Testing after Spinal Cord Injury in Rats

Spinal cord injury (SCI) impairs sensory systems causing allodynia. To identify cellular and molecular causes of allodynia, sensitive and valid sensory testing in rat SCI models is needed. However, until recently, no single testing approach had been validated for SCI so that standardized methods have not been implemented across labs. Additionally, available testing methods could not be implemented acutely or when severe motor impairments existed, preventing studies of the development of SCI-induced allodynia(3). Here we present two validated sensory testing methods using von Frey Hair (VFH) monofilaments which quantify changes in tactile sensory thresholds after SCI. One test is the well-established Up-Down test which demonstrates high sensitivity and specificity across different SCI severities when tested chronically. The other test is a newly-developed dorsal VFH test that can be applied acutely after SCI when allodynia develops, prior to motor recovery. Each VFH monofilament applies a calibrated force when touched to the skin of the hind paw until it bends. In the up-down method, alternating VFHs of higher or lower forces are used on the plantar L5 dermatome to delineate flexor withdrawal thresholds. Successively higher forces are applied until withdrawal occurs then lower force VFHs are used until withdrawal ceases. The tactile threshold reflects the force required to elicit withdrawal in 50% of the stimuli. For the new test, each VFH is applied to the dorsal L5 dermatome of the paw while the rat is supported by the examiner. The VFH stimulation occurs in ascending order of force until at least 2 of 3 applications at a given force produces paw withdrawal. Tactile sensory threshold is the lowest force to elicit withdrawal 66% of the time. Acclimation, testing and scoring procedures are described. Aberrant trials that require a retest and typical trials are defined. Animal use was approved by Ohio State University Animal Care and Use Committee.

Research on the Fatigue Strength Test of 20CrMnMo Carburized and Quenched Gears

This paper discussed on the research of fatigue strength test of 20CrMnMo carburized and quenched gears. This test is done through a fatigue machine of high-frequency electromagnetic resonant with pulse double-tooth loading. In the short-life area, give four levels of constant stress group test; in the long-life area, adopt up-down test method. According to the experimental data obtained in the tests and statistical theory, complete the C-R-S-N curve, and assess the values of limit stress under different reliabilities.

Echo thresholds for reflections from acoustically diffusive architectural surfaces

Diffusive architectural surfaces play an important role in performance venue design for architectural expression and proper sound distribution. However, previous psychoacoustic research on perception of reflections and the precedence effect has focused on specular reflections. This study compares the echo threshold of specular reflections, measured using an adaptive up-down method with music and speech stimuli, against those for reflections from realistic architectural surfaces, and against synthesized reflections that isolate individual qualities of reflections from diffusive surfaces, namely temporal dispersion and spectral coloration. It is found that temporal dispersion up to 16ms in the reflection response, and peak amplitude reduced as much as 18.5 dB results in an echo threshold shorter than that for a specular reflection of comparable amplitude. Rather, the threshold is comparable to that of a specular reflection of similar energy. This indicates that the auditory system integrates the temporally dispersed energy into a single stream.

Study on Surrounding Rock Deformation Discipline of Extra-Large Section Super-Shallow-Buried Tunnel

The type B section of Hongqihegou station is cross section and its excavation section area is about 730 m2. This section is located in rail transit line 3 at the center of Chongqing. For this reason, the heavy traffic, large amount buildings and pipelines surrounding, super-shallow-buried depth and small cross-cover ratio (only 0.4) become the determinant factor in tunnel construction. By using a new method—the up-down sidewall drift method combined with first-wall-and-then-arch method, the Hongqihegou station was successfully completed. Through the analysis of the monitoring measurement data, the discipline of surrounding rock deformation during construction is revealed.

The Intrathecally Administered Kappa-2 Opioid Agonist GR89696 and Interleukin-10 Attenuate Bone Cancer–Induced Pain Through Synergistic Interaction

Although bone cancer-related pain is one of the most disruptive symptoms in patients with advanced cancer, patients are often refractory to pharmacological treatments; thus, more effective treatments for bone cancer pain are needed. We evaluated the analgesic efficacy of and interaction between intrathecal GR89696, a κ(2)-opioid receptor agonist, and interleukin (IL)-10 in a rat model of bone cancer pain. The rat model of bone cancer pain was produced by right tibia intramedullary injection of rat breast cancer cells, and an intrathecal catheterization was performed. Ten days later, a paw-withdrawal threshold to mechanical stimulus by von Frey hairs was measured using the up-down method, after intrathecal administration of GR89696 and IL-10. The interaction between the 2 drugs was also evaluated using an isobolographic analysis. Intrathecal GR89696 and IL-10 significantly increased the paw withdrawal threshold of the cancer cell-implanted rat, in a dose-dependent manner, with 50% effective dose values (95% confidence interval) of 50.78 μg (31.80-80.07μg) and 0.83 μg (0.59-1.15 μg), respectively. Isobolographic analysis revealed a synergistic interaction between intrathecal GR89696 and IL-10. Intrathecally administered GR89696 and IL-10 attenuated bone cancer-induced pain, and the 2 drugs interacted synergistically in the spinal cord. These results raise the intriguing possibility of κ(2)-opioid receptor agonists and IL-10 as a new therapeutic approach for the management of bone cancer-associated pain.