Increase in hippocampal theta oscillations during spatial decision making

The processing of spatial and mnemonic information is believed to depend on hippocampal theta oscillations (5–12 Hz). However, in rats both the power and the frequency of the theta rhythm are modulated by locomotor activity, which is a major confounding factor when estimating its cognitive correlates. Previous studies have suggested that hippocampal theta oscillations support decision‐making processes. In this study, we investigated to what extent spatial decision making modulates hippocampal theta oscillations when controlling for variations in locomotion speed. We recorded local field potentials from the CA1 region of rats while animals had to choose one arm to enter for reward (goal) in a four‐arm radial maze. We observed prominent theta oscillations during the decision‐making period of the task, which occurred in the center of the maze before animals deliberately ran through an arm toward goal location. In speed‐controlled analyses, theta power and frequency were higher during the decision period when compared to either an intertrial delay period (also at the maze center), or to the period of running toward goal location. In addition, theta activity was higher during decision periods preceding correct choices than during decision periods preceding incorrect choices. Altogether, our data support a cognitive function for the hippocampal theta rhythm in spatial decision making. © 2014 The Authors Hippocampus Published by Wiley Periodicals, Inc.     

输注速度和刺激对全麻诱导时依托咪酯所致肌阵挛的影响

目的 通过观察不同给药速度以及在麻醉诱导过程中给予刺激对依托咪酯进行全麻诱导时发生肌阵挛的影响,分析肌阵挛的诱发因素.方法 200例ASA Ⅰ～Ⅱ级的患者随机分为四组：慢诱导组（S组）、慢诱导刺激组（S-s组）、快诱导组（F组）、快诱导刺激组（F-s组）,各50例.四组患者麻醉诱导均采用依托咪酯0.3 mg/kg.S组与S-s组输注时间均为1 min,F组与F-s组输注时间为10s.S组与F组待睫毛反射消失、呼吸变浅后开始行辅助通气,S-s组与F-s组待意识消失即刻开始行正压机械通气.记录四组患者麻醉前、依托咪酯注药后3 min内平均动脉压（MAP）、心率（HR）、脉搏血氧饱和度（SPO2）变化;观察静脉注射依托咪酯后肌阵挛的发生情况以及严重程度.结果 S组患者与F组患者肌阵挛发生率无明显差异,S-s组与S组相比以及F-s组与F组相比,其肌阵挛发生率均增高（P＜0.01）,但S-s组与F-s组相比肌阵挛发生率稍低（P＜0.01）.此外S-s组与F-s组注药后MAP及HR较基础值有所升高,SPO2则呈下降趋势（P＜0.01）,其余两组无明显变化.结论 全麻诱导时,加快输注速度并不会增加依托咪酯所致肌阵挛的发生率,但若在麻醉深度不够时给予了刺激则易诱发肌阵挛的发生.     

Walking speed estimation using foot-mounted inertial sensors: Comparing machine learning and strap-down integration methods

In this paper we implemented machine learning (ML) and strap-down integration (SDI) methods and analyzed them for their capability of estimating stride-by-stride walking speed. Walking speed was computed by dividing estimated stride length by stride time using data from a foot mounted inertial measurement unit. In SDI methods stride-by-stride walking speed estimation was driven by detecting gait events using a hidden Markov model (HMM) based method (HMM-based SDI); alternatively, a threshold-based gait event detector was investigated (threshold-based SDI). In the ML method a linear regression model was developed for stride length estimation. Whereas the gait event detectors were a priori fixed without training, the regression model was validated with leave-one-subject-out cross-validation. A subject-specific regression model calibration was also implemented to personalize the ML method.Healthy adults performed over-ground walking trials at natural, slower-than-natural and faster-than-natural speeds. The ML method achieved a root mean square estimation error of 2.0% and 4.2%, with and without personalization, against 2.0% and 3.1% by HMM-based SDI and threshold-based SDI. In spite that the results achieved by the two approaches were similar, the ML method, as compared with SDI methods, presented lower intra-subject variability and higher inter-subject variability, which was reduced by personalization.     

Kinematics of 2 Reciprocating Endodontic Motors: The Difference between Actual and Set Values

Introduction

The aim of this study was to evaluate the kinematics of 2 reciprocating motors and compare it with manufacturers' declared values.

Methods

VDW Silver (VDW, Munich, Germany) and ATR Tecnika (Tecnika, Pistoia, Italy) were used in the study in 5 working modes: continuous rotation at 400 rpm on VDW Silver and ATR Tecnika and reciprocating motion on ATR Tecnika at 400 rpm and on VDW Silver in Reciproc and WaveOne mode. The polishing disk with an optical target was inserted in the contra-angle and recorded with a 1000–frames per second video camera. The direction and the amount of rotation were analyzed by computer, and the following kinematics parameters were calculated: engaging and disengaging angles, cycle rotational speeds, engaging and disengaging rotational speeds, net cycle angle, total cycle angle, and number of cycles to complete full rotation. One-way analysis of variance followed by planned pair-wise comparisons was used to compare kinematics parameters. The alpha error was set to 0.05.

Results

Analysis of variance revealed a difference between actual and set values of all 3 reciprocating modes in all kinematics parameters (P < .001). No significant difference between the actual engaging angle of Reciproc and that of the WaveOne mode was found. For reciprocating motion on the ATR Tecnika at 400 rpm, the actual engaging and disengaging angles were 8- and 9-fold greater, respectively, compared with set angles (P < .001).

Conclusions

The kinematics of reciprocating instrumentation is more complex than it seems as described only with angles and rotational speed. Actual kinematics values differ from manufacturers' declared values.     

口腔颌面部高速投射物伤致牙周膜间接损伤的实验研究

目的：研究口腔颌面部高速投射物伤导致的牙周膜间接损伤的特点。方法：将18只实验犬随机分为6组,以直径6．0 mm、质量0．88 g的高速投射物致伤右下颌骨体部第四前磨牙根尖下方区域,但不直接伤及牙齿;分别于伤后6h、24h、3d、7d、2w及4w处死实验犬,观察右下颌第四前磨牙、第二前磨牙及左下颌第二前磨牙牙周膜的组织病理学表现。结果：右下颌第四前磨牙和第二前磨牙的牙周膜损伤较明显,但病理学变化可逆;左下颌第二前磨牙牙周膜仅见一过性血管扩张、充血。结论：口腔颌面部高速投射物伤可导致牙周膜发生间接损伤,病理学变化可逆;损伤程度随着牙齿与伤区距离的增加而递减。     

复心片与复方丹参滴丸治疗稳定型心绞痛的对照研究

目的观察复心片与复方丹参滴丸治疗冠心病稳定型心绞痛的临床疗效,并对其安全性作出评价。方法采用随机对照,治疗组100例给予复心片(2片/次,3次/日)口服,对照组60例给予复方丹参滴丸(10丸/次,3次/日)口服,8周后进行心绞痛,主要症状总疗效及毒副作用评估。结果治疗组对轻、中、重度心绞痛均有很好疗效,总有效率97%,对照组95%,两组比较无明显差异(P>0.05);治疗组心电图总有效率77%,对照组70%(P>0.05)。结论复心片是治疗稳定型心绞痛的有效药物。     

缓速和快速插胃管法的效果对比

目的探讨胃管插入速度与一次插管成功率及患者反应之间的关系。方法将98例需插胃管的意识清醒的患者随机分为两组,分别采用缓速插管法和快速插管法插入胃管,比较两组插管所需时间、一次插管成功率及患者的反应情况。结果缓速插管法和快速插管法所需时间分别为(25±3.2)s、(12±0.8)s,一次插管成功分别为47例和38例,两组的插管时间、一次成功率和患者反应均有显著性差异(P<0.05或P<0.01)。结论缓速插管法优于快速插管法。     

Effects of Walking Speed on Total and Regional Body Fat in Healthy Postmenopausal Women

Introduction: This study had two aims: (1) To confirm the efficacy of exercise speed and impulse (session duration at a given speed) to produce total and abdominal fat loss in postmenopausal women, and (2) compare the exercise speed and impulse necessary for the stimulation of fat loss to the suppression of bone mineral loss. Of special interest was to compare these parameters of exercise on fat loss in the same study and with the same subjects where they were found to suppress bone mineral loss. We hypothesized that (1) more total fat will be lost with slow walking and a longer impulse than with fast speed and shorter impulse, and (2) more abdominal subcutaneous (SC) and visceral fat (VF) will be lost with fast walking speed. Materials and Methods: Fat loss and suppression of bone mineral loss were measured in the same 25 subjects after 15 weeks, and fat measurements were also taken after 30 weeks in 16 residual subjects. Study parameters were walking a 4.8 km distance 4 days/week at either 6.6 km/h (120% of ventilatory threshold (VT)) or at 5.5 km/h (101.6% of VT) and expending 300 kcal/session. Body composition (fat and lean body mass, LBM) was measured with dual-energy X-ray absorptiometry (DXA) and anthropometric methods. Results: Slow walkers in the residual group progressively lost a significant percent of total body fat over 30 weeks while no such loss occurred after 15 weeks in fast walkers in either group, supporting hypothesis 1. However, the 20% higher starting body fat in 16 residual slow relative to fast subjects suggests that exercise fat loss is greater in overweight than in lean subjects. In fast walkers, fat loss occurred after 30 weeks of training. Hypothesis 2 was not supported as both speeds led to equal VF loss in 30-week group as estimated by waist circumference (CF) confirming that VF responds to the magnitude of energy expenditure and not the walking speed. Conclusions: Total body fat is lost through walking at all speeds, but the change is more rapid, clear, and initially greater with slow walking in overweight subjects. A longer exercise impulse at a lower speed in our study initially produced greater total fat loss than a shorter one with fast walking speed. This was reversed in comparison to how the same exercise in the same subjects suppressed bone mineral loss. Data from other studies indicate that longer impulses may promote greater fat loss at both slow and high exercise speeds, and our study providing only a 4.8 km walking distance may have limited the walking impulse and the magnitude of fat loss. Increased exercise energy expenditure at either walking speed produces equivalent declines in visceral fat in postmenopausal women, and with sufficiently long impulses, should reduce disabilities associated with central obesity.