Noise,not stimulus entropy,determines neural information rate

In the quest for deciphering the neural code, theoretical advances were made which allow for the determination of the information rate inherent in the spike trains of nerve cells. However, up to now, the dependence of the information rate on stimulus parameters has not been studied in any neuron in a systematic way. Here, I investigate the information carried by the spike trains of H1, a motion-sensitive visual interneuron of the blowfly (Calliphora vicina) using a moving grating as a stimulus. Stimulus parameters fall in two classes: those that have only a minor effect on the information rate like increasing the frequency bandwidth or the maximum amplitude of the stimulus velocity, and those which dramatically affect the neural information rate, like varying the spatial size or the contrast of the visual pattern being moved. It appears that, for a broad range of complex stimuli, the neuron covers the stimulus with its whole response repertoire regardless of the stimulus entropy, with the information rate being limited by the noise of the stimulus and the neural hardware.     

超声引导下隐神经联合IPACK阻滞对老年全膝关节置换术患者应激反应、炎性细胞因子及膝关节活动度的影响

摘要 目的：探讨超声引导下隐神经联合腘动脉与膝关节后囊间隙（IPACK）阻滞对老年全膝关节置换术（TKA）患者应激反应、炎性细胞因子及膝关节活动度的影响。方法：根据随机数字表法,将无锡市中医医院2021年3月~2022年9月期间收治的102例初次行TKA的老年患者分为观察组（超声引导下隐神经联合IPACK阻滞镇痛处理）和对照组（超声引导下隐神经镇痛处理）,每组各51例。对比两组疼痛情况、炎性细胞因子、应激反应指标、不良反应发生率、膝关节活动度。结果：观察组术后6 h、术后12 h、术后24 h视觉模拟评分法（VAS）评分低于对照组（P<0.05）。观察组术后48 h肿瘤坏死因子-α（TNF-α）、白细胞介素（IL）-6、IL-1β、β-淀粉样蛋白（Aβ）低于对照组（P<0.05）。观察组术后48 h血管紧张素Ⅱ（AngⅡ）、皮质醇（COR）低于对照组（P<0.05）。观察组术后24 h、术后48 h膝关节活动度大于对照组（P<0.05）。两组不良反应发生率对比无差异（P>0.05）。结论：超声引导下隐神经联合IPACK阻滞用于TKA患者,具有较好的镇痛效果,可减轻应激反应,抑制炎性细胞因子过度分泌,改善膝关节活动度,麻醉效果较好。     

细菌显微追踪技术在生物被膜中的应用

细菌生物被膜是粘附于物体表面的由细菌细胞及其胞外物质组成的复杂膜样物聚集体,具有很强的耐药性和免疫逃逸能力。生物被膜内细菌的代谢活性、运动状态等与浮游细菌有明显区别。近年来,先进的显微成像技术结合新型图像处理方法,在研究细菌的运动、生理等方面发挥了重要作用。本文围绕生物被膜,概述了细菌显微追踪技术在其研究中的应用。主要从细菌的运动方式和生物被膜形成过程的调控两方面出发,介绍了在单细胞水平上利用该技术研究生物被膜的进展,包括细菌的游泳、蹭行、群集运动和多种信号通路调控下生物被膜的形成过程等,并展望了该技术在生物被膜其他相关研究领域的应用前景。     

Detection of Architectural Distortion in Prior Mammograms via Analysis of Oriented Patterns

We demonstrate methods for the detection of architectural distortion in prior mammograms of interval-cancer cases based on analysis of the orientation of breast tissue patterns in mammograms. We hypothesize that architectural distortion modifies the normal orientation of breast tissue patterns in mammographic images before the formation of masses or tumors. In the initial steps of our methods, the oriented structures in a given mammogram are analyzed using Gabor filters and phase portraits to detect node-like sites of radiating or intersecting tissue patterns. Each detected site is then characterized using the node value, fractal dimension, and a measure of angular dispersion specifically designed to represent spiculating patterns associated with architectural distortion.Our methods were tested with a database of 106 prior mammograms of 56 interval-cancer cases and 52 mammograms of 13 normal cases using the features developed for the characterization of architectural distortion, pattern classification via quadratic discriminant analysis, and validation with the leave-one-patient out procedure. According to the results of free-response receiver operating characteristic analysis, our methods have demonstrated the capability to detect architectural distortion in prior mammograms, taken 15 months (on the average) before clinical diagnosis of breast cancer, with a sensitivity of 80% at about five false positives per patient.     

Unweighted state as a sidestep preparation improve the initiation and reaching performance for basketball players

The preparatory motion of a defensive motion in contact sport such as basketball should be small and involve landing on both feet for strict time and motion constraints. We thus proposed the movement creating a unweighted state. Ten basketball players performed a choice reaction sidestepping task with and without the voluntary, continuous vertical fluctuation movement. The results indicated that the preparatory movement shortened the time of their sidestep initiation (301 vs. 314 ms, p = 0.011) and reaching performance (883 vs. 910 ms, p = 0.018) but did not increase their peak ground reaction force or movement velocity. The mechanism of the improvement was estimated to be the following: in the preparation phase, the vertical body fluctuation created the force fluctuation; after the direction signal, the unweighted state can shorten the time required to initiate the sidestepping (unweighted: 279 ms; weighted: 322 ms, p = 0.002); around the initiation phase, the dropping down of the body and weighted state can contribute to the reaching performance. We conducted additional experiment investigating muscle–tendon-complex dynamics and muscle activity using ultrasound device and electromyography. The result suggests that the building up of active state of muscle might explain the improvement of sidestepping performance.     

Movement of the S4 segment in the hERG potassium channel during membrane depolarization

Abstract

The hERG potassium channel is a member of the voltage gated potassium (Kv) channel family, comprising a pore domain and four voltage sensing domains (VSDs). Like other Kv channels, the VSD senses changes in membrane voltage and transmits the signal to gates located in the pore domain; the gates open at positive potentials (activation) and close at negative potentials, thereby controlling the ion flux. hERG, however, differs from other Kv channels in that it is activated slowly but inactivated rapidly – a property that is crucial for the role it plays in the repolarization of the cardiac action potential. Voltage-gating requires movement of gating charges across the membrane electric field, which is accomplished by the transmembrane movement of the fourth transmembrane segment, S4, of the VSD containing the positively charged arginine or lysine residues. Here we ask if the functional differences between hERG and other Kv channels could arise from differences in the transmembrane movement of S4. To address this, we have introduced single cysteine residues into the S4 region of the VSD, expressed the mutant channels in Xenopus oocytes and examined the effect of membrane impermeable para-chloromercuribenzene sulphonate on function by the two-electrode voltage clamp technique. Our results show that depolarization results in the accessibility of seven consecutive S4 residues, including the first two charged residues, K525 and R528, to extracellularly applied reagent. These data indicate that the extent of S4 movement in hERG is similar to other Kv channels, including the archabacterial KvAP and the Shaker channel of Drosophila.     

Wieviorka's view on multiculturalism: a critique

Like any other society France is increasingly diversified culturally and in terms of collective identities. Clearly it is a multicultural, multi-identificational society, but it is not often willing to discuss openly the changes needed to accommodate its diversity and its de facto multicultural character. Michel Wieviorka has been courageous in trying to launch this crucial debate. In France his work is often appreciated but it is also often held to be ‘politically incorrect’ precisely because it questions the validity of the French republican model and its adequacy for the deep social changes at work in French society, and also because it raises the issue of the necessity of building a French multiculturalism. In this article the most important insights of Wieviorka's perspectives on multiculturalism are presented and some of the problems it implies are discussed.     

Evaluation of intrafractional head motion for intracranial stereotactic radiosurgery with a thermoplastic frameless mask and ceiling-floor-mounted image guidance device

PurposeTo evaluate intrafractional head motion (IFM) in patients who underwent intracranial stereotactic radiosurgery with the ExacTrac X-ray system (ETX) and a frameless mask.MethodsA total of 143 patients who completed a pre-treatment examination for IFM were eligible for this study. The frameless mask type B R408 (Klarity Medical & Equipment Co., Ltd., Guangzhou, China), which covers the back of the head, and the entire face, was used for patient immobilization. After the initial 6D correction and first X-ray verification (IFM₁), X-ray verification was performed every 3 min for a duration of 15 min. The IFM_p (2 ≤ p ≤ 6) was calculated as the positional difference from IFM₁. In addition, the inter-phase IFM (IP-IFM) and IFM_m were calculated. The IP-IFM was defined as |IFM_p − IFM_p-1|, and IFM_m as the difference between the values after all patients were asked to move their heads intentionally with the frameless mask on.ResultsBoth translational IFM_p and IP-IFM exceeded 1 mm for a single patient, whereas, for all patients, the translational IFM_m values were kept to within 1 mm in all directions. The proportions of the rotational IFM_p, IP-IFM, and IFM_m values within 0.5° were greater than 94.4%, 98.6%, and 90.2% for all of the rotational axes, respectively.ConclusionsA frameless mask achieved highly accurate patient positioning in combination with ETX and a 6°-of-freedom robotic couch; however, a deviation over 1 mm and 0.5° was observed with low frequency. Therefore, X-ray verification and correction are required during treatment.