Multi-circular formation control with reinforced transient profiles for nonholonomic vehicles:A path-following framework

This article investigates a multi-circular path-following formation control with reinforced transient profiles for nonholonomic vehicles connected by a digraph.A multi-circular formation controller endowed with the feature of spatial-temporal decoupling is devised for a group of vehicles guided by a virtual leader evolving along an implicit path,which allows for a circumnavigation on multiple circles with an anticipant angular spacing.In addition,notice that it typically imposes a stringent time constraint on time-sensitive enclosing scenarios,hence an improved prescribed performance control(IPPC)using novel tighter behavior boundaries is presented to enhance transient capabilities with an ensured appointed-time convergence free from any overshoots.The significant merits are that coordinated circumnavigation along different circles can be realized via executing geometric and dynamic assignments independently with modified transient profiles.Furthermore,all variables existing in the entire system are analyzed to be convergent.Simulation and experimental results are provided to validate the utility of suggested solution.

A Novel Prescribed-Performance Path-Following Problem for Non-Holonomic Vehicles

The issue of achieving prescribed-performance path following in robotics is addressed in this paper,where the aim is to ensure that a desired path within a specified region is accu-rately converged to by the controlled vehicle.In this context,a novel form of the prescribed performance guiding vector field is introduced,accompanied by a prescribed-time sliding mode con-trol approach.Furthermore,the interdependence among the pre-scribed parameters is discussed.To validate the effectiveness of the proposed method,numerical simulations are presented to demonstrate the efficacy of the approach.

The Alienation of Nature in Emily Dickinson’s Poems through the Prism of Taoism

In the poems created by the renowned American poet Emily Dickinson,those related to nature constitute a considerable proportion.However,Dickinson’s attitude toward nature is,in fact,contradictory.On the one hand,Dickinson perceives nature as gentle and kind,akin to a mother.Nature is regarded as“heaven”and embodies harmony.On the other hand,nature possesses its own operational principles and harbors inherent cruelty.According to Dickinson,humans should refrain from excessive interference in the natural order.This article attempts to analyze the similarities in attitude towards nature between Dickinson’s poetry and Taoist philosophy.

Problems and Development Suggestions of Nature Education in Jiangxi Province

The forest coverage rate of Jiangxi Province ranks second in China.It has rich natural resources,a long history of ancient color culture and rich red culture.In the development of nature education,Jiangxi Province has great potential and advantages.This paper introduces the development conditions of nature education in Jiangxi Province,summarizes the problems existing in the development of nature education in Jiangxi Province from the aspects of the types of nature education and the construction of nature education base,such as simple content and single form,imperfect infrastructure and lack of professionals,and puts forward some suggestions on the development of nature education in Jiangxi Province.

《Nature》子刊:苏佳琪等开发基于牛奶的水凝胶,用作酒精中毒的解毒剂

近日,苏黎世联邦理工学院Raffaele Mezzenga、苏佳琪等人在《Nature》子刊《Nature Nanotechnology》上发表的一篇研究显示,该研究开发了一种口服的、基于牛奶蛋白的水凝胶——FeSA@FibBLG,或可作为急性酒精中毒的有效解毒剂,能够稳定耐受胃酸消化且持续显著降低酒精中毒小鼠血液中的酒精水平,同时避免额外积累有毒的乙醛,还可增强肝脏保护,并显著减轻肠道损伤和生态失调,强调了其作为酒精相关疾病的新疗法的潜力。

Nature’s Gift

NATURAL WONDERS IN CHINA AND AFRICA Qilian Mountains National Park Located in Northwest China’s Gansu and Qinghai provinces,Qilian Mountains National Park spans 50,200 square km,serving as a vital ecological security barrier and water source conservation area in west China.Established in 2017 to address ecosystem damage,intensive food chain protection and wildlife monitoring in the area began in early 2011.

Spatiotemporal Evolution of Ecological Quality in Alpine Freshwater Lake Nature Reserves in the Past 20 Years

The Caohai Nature Reserve is one of the three major plateau freshwater lakes in China.Since the 1950s,human activities such as land reclamation and population relocation have greatly damaged Caohai.A rapid evaluation of the spatiotemporal evolution trend of the ecological quality of the Caohai Nature Reserve is significant for the maintenance and construction of the ecosystem in this area.The research is based on the Google Earth Engine(GEE)remote sensing cloud computing platform.Landsat TM/OLI images from May to October in five time periods:2000-2002,2004-2006,2009-2011,2014-2016,and 2019-2021 were obtained to reconstruct the optimal cloud image set by averaging the images in each time period.By constructing four ecological indicators:Greenness(NDVI),Wetness(Wet),Hotness(LST),and Dryness(NDBSI),and using Principal Component Analysis(PCA)method to obtain the Remote Sensing Ecological Index(RSEI)for the corresponding years,the spatiotemporal variation of ecological quality in the Caohai Nature Reserve over 20 years was analyzed.The results indicate:①the mean value of RSEI increased from 0.460 in 2000-2002 to 0.772 in 2019-2021,a 67.83%increase,indicating a significant improvement in the ecological quality of the reserve over the 20 years;②from the perspective of functional zoning of the Caohai Nature Reserve,the ecological quality of the core area showed a degrading trend,while the ecological quality of the buffer zone and experimental zone significantly improved;③with the implementation of ecological restoration projects,the ecological quality of the reserve gradually recovered and improved from 2014 to 2021.The trend of RSEI value changes is well correlated with human interventions,indicating that the PCA-based RSEI model can be effectively used for ecological quality assessment in lake areas.

《Nature》:新开发的可穿戴超声贴片可连续、无创监测大脑血流

近日,一篇发表在《Nature》上的研究显示,研究人员开发出一种可穿戴超声贴片(wearable ultrasound patch),其可对大脑血流进行连续、无创的监测。该研究将贴片在36名健康志愿者身上进行了测试,以检验其测量脑部主要动脉血流速度(收缩期峰值、平均流速和舒张末期速度)的能力,发现测量结果与传统超声探头的测量结果非常吻合。

《Nature》:科学家发现能驱动患者狼疮发生的两种细胞缺陷

近日,一篇发表在《Nature》上的研究显示,研究发现了一种特殊的分子缺陷或会促进系统性红斑狼疮的病理性免疫反应,同时揭示了逆转这一缺陷或有望逆转疾病。该研究中,研究人员报道了驱动狼疮发生的新通路,研究者表示,患者体内血液中的多种分子都会发生疾病相关的改变,最终,这些变化会导致芳香烃受体(aryl hydrocarbon receptor,AHR)所控制的通路激活不足,AHR能调节细胞对环境污染物、细菌或代谢产物的反应。

缺乏位置信息的视觉移动机器人leader-following编队控制

针对视觉移动机器人编队在缺乏位置信息情况下的控制问题,提出一种基于视觉的leader-following编队反馈控制方法。该方法利用leader标志物特征点在follower摄像机像平面上的坐标信息设计了观测器,对leader与follower间的相对位置进行估计,基于相对位置估计量与它们速度的关系,设计出leader-following编队反馈控制器,通过Lyapunov理论证明了闭环系统的稳定性。仿真结果表明,该控制方法能有效解决缺乏位置信息情况下视觉移动机器人编队的控制问题。

“Eternal Motion” as a “Form of Movement of a Special Nature” and the Main Condition for the Creation of the Universe

The article hypothesizes that DE and DM (UCM) are a “Form of Motion of a Special Nature”, where “Form of Motion” means “Eternal Motion” as the power of dynamics of different levels and varying degrees of self-sufficiency, and by “Special Nature”, gravitational and two other properties of matter, “tied” to the “Eternal Movement” and completely dependent on it. Carriers of key properties of a “Special Nature” have been established: “0”-DE particles and “3”-DM particles (UDM). The unity of their inherent “motionally-gravitational” properties and the peculiarity of the relationship between “motion” and “gravity” are revealed: the higher the intensity of “Eternal Motion”, the stronger the gravitational properties of matter are manifested (and vice versa). The relationship of “time” with the “vibration frequency” and the “mass” of photons with the “degree of bonding and deformation properties of the field” is shown. The maximum level of gravity has been determined, which allows Nature to successfully create the Universe: such a landmark is the proximity to the property of the Primary Source—the “pure graviton” of the OSP space, the most powerful “motionally-gravitational” particle of the Universe. The reasons for the emergence of such an identity of the gravitational properties of particles with the indicators of a “pure graviton” are established: for “0”-DE particles, this is the acquisition of the function of “freedom of movement”;for “3”-DM particles (UDM), the creation of a special structure—a “double field” (“Main” and “Small”). The presence in the “double field” of specific “tools” for the creation of the worlds of the Universe—gravitational “waves” gives rise to impulses (shocks) of varying intensity and shape. A list of functions performed by “waves” in the “Main” and “Small” fields has been compiled. The specific conditions for the formation of “UDM Streams”, their transformation into a “Vortex” and, under the influence of a powerful Initial Impulse (push), sending them to the “place” of the creation of galaxies, are shown. It is suggested that there is a “Cycle of Matter in Nature” in the closed structure of our Universe due to the “work” of “waves” and the functioning of special “factories” in the form of exotic space objects—Black holes.

Leader-following多自主体系统时变编队跟踪控制

考虑时变时延,研究了高阶leader-following多自主体系统的分布式时变编队跟踪控制问题.针对连续高阶多自主体系统,设计了基于观测器的时变编队跟踪控制协议,通过状态变换,将系统的时变编队跟踪控制问题,转变为误差系统的稳定性问题.然后利用图论及李雅普诺夫稳定定理,研究了系统实现时变编队跟踪控制的充分条件,并且指出时变编队参考函数与时变时延无关.最后,数据仿真结果证明了所设计的协议能使follower自主体实现时变编队,并且跟踪leader自主体的轨迹.

Finite-Time Sideslip Differentiator-Based LOS Guidance for Robust Path Following of Snake Robots

This paper presents a finite-time sideslip differentiator-based line-of-sight(LOS)guidance method for robust path following of snake robots.Firstly,finite-time stable sideslip differentiator and adaptive LOS guidance method are proposed to counteract sideslip drift caused by cross-track velocity.The proposed differentiator can accurately observe the cross-track error and sideslip angle for snake robots to avoid errors caused by calculating sideslip angle approximately.In our method,the designed piecewise auxiliary function guarantees the finite-time stability of position errors.Secondly,for the case of external disturbances and state constraints,a Barrier Lyapunov functionbased backstepping adaptive path following controller is presented to improve the robot’s robustness.The uniform ultimate boundedness of the closed-loop system is proved by analyzing stability.Additionally,a gait frequency adjustment-based virtual velocity control input is derived to achieve the exponential convergence of the tangential velocity.At last,the availability and superiority of this work are shown through simulation and experiment results.

Constrained Moving Path Following Control for UAV With Robust Control Barrier Function

This paper studies the moving path following(MPF)problem for fixed-wing unmanned aerial vehicle(UAV)under output constraints and wind disturbances.The vehicle is required to converge to a reference path moving with respect to the inertial frame,while the path following error is not expected to violate the predefined boundaries.Differently from existing moving path following guidance laws,the proposed method removes complex geometric transformation by formulating the moving path following problem into a second-order time-varying control problem.A nominal moving path following guidance law is designed with disturbances and their derivatives estimated by high-order disturbance observers.To guarantee that the path following error will not exceed the prescribed bounds,a robust control barrier function is developed and incorporated into controller design with quadratic program based framework.The proposed method does not require the initial position of the UAV to be within predefined boundaries.And the safety margin concept makes error-constraint be respected even if in a noisy environment.The proposed guidance law is validated through numerical simulations of shipboard landing and hardware-in-theloop(HIL)experiments.

Mushroomβ-glucan and polyphenol formulations as natural immunity boosters and balancers:nature of the application

Mushrooms are experiencing a kind of renaissance as a part of the contemporary human diet.These valuable organisms are more than food,they fit in perfectly as a novel market group known as nutra-mycoceuticals.Immune-balancing mushroom dietary fibers and secondary metabolites such as polyphenols are the main focus of the healthcare industry.Wellness and cosmetic companies are increasingly using mushroom extracts rich in these ingredients.This review considers the basic molecular immunomodulatory mechanisms of action of the most commonly used mushroom dietary fibers,β-glucans.The literature data on their bioavailability,metabolic transformations,preclinical and human clinical research,and safety are discussed.Immunomodulatory mechanisms of polyphenol ingredients are also considered.These molecules present great potential in the design of the new immunity balancer formulations according to their widespread structural diversity.Finally,we draw attention to the perspectives of modern trends in mushroom nutraceutical and cosmeceutical formulations to strengthen and balance immunity.

LSTM-DPPO based deep reinforcement learning controller for path following optimization of unmanned surface vehicle

To solve the path following control problem for unmanned surface vehicles(USVs),a control method based on deep reinforcement learning(DRL)with long short-term memory(LSTM)networks is proposed.A distributed proximal policy opti-mization(DPPO)algorithm,which is a modified actor-critic-based type of reinforcement learning algorithm,is adapted to improve the controller performance in repeated trials.The LSTM network structure is introduced to solve the strong temporal cor-relation USV control problem.In addition,a specially designed path dataset,including straight and curved paths,is established to simulate various sailing scenarios so that the reinforcement learning controller can obtain as much handling experience as possible.Extensive numerical simulation results demonstrate that the proposed method has better control performance under missions involving complex maneuvers than trained with limited scenarios and can potentially be applied in practice.

Biomimetic natural biomaterials for tissue engineering and regenerative medicine:new biosynthesis methods,recent advances,and emerging applications

Biomimetic materials have emerged as attractive and competitive alternatives for tissue engineering(TE)and regenerative medicine.In contrast to conventional biomaterials or synthetic materials,biomimetic scaffolds based on natural biomaterial can offer cells a broad spectrum of biochemical and biophysical cues that mimic the in vivo extracellular matrix(ECM).Additionally,such materials have mechanical adaptability,micro-structure interconnectivity,and inherent bioactivity,making them ideal for the design of living implants for specific applications in TE and regenerative medicine.This paper provides an overview for recent progress of biomimetic natural biomaterials(BNBMs),including advances in their preparation,functionality,potential applications and future challenges.We highlight recent advances in the fabrication of BNBMs and outline general strategies for functionalizing and tailoring the BNBMs with various biological and physicochemical characteristics of native ECM.Moreover,we offer an overview of recent key advances in the functionalization and applications of versatile BNBMs for TE applications.Finally,we conclude by offering our perspective on open challenges and future developments in this rapidly-evolving field.

Knowledge,perceptions,and practice towards adverse events following immunization surveillance among vaccination workers in Zhejiang province,China

Objective:To access the level of knowledge,perceptions,and practice towards adverse events following immunization(AEFI)surveillance among vaccination workers in Zhejiang province,China.Methods:This was a cross-sectional survey involving 768 vaccination workers.Data were collected using self-administered questionnaires and analyzed by using SAS 9.3 software.Knowledge,perceptions,and practice on AEFI surveillance were summarized using frequency tables.The mean±SD value was used as the cut-off for defining good(values≥mean)and poor(values<mean)knowledge,perceptions or practice.Binary logistic regression analysis was used to determine sociodemographic variables associated with knowledge,perceptions,and practice towards AEFI.Results:The proportions of good knowledge,perceptions and practice on AEFI surveillance were 78.13%,57.81%and 66.15%,respectively.Having a higher education background,longer years of experience,previous training on AEFI and≥30 years of age were factors associated with good knowledge,perceptions and practice on AEFI surveillance among vaccination workers.Conclusions:Over half of the respondents had good knowledge,perceptions and practice on AEFI surveillance work.Interventions on improving the vaccination workers’knowledge,perceptions and practice on AEFI surveillance should be considered in order to develop a more effective surveillance system.

Effects of serum containing natural cerebrolysin on glucose-regulated protein 78 and CCAAT enhancer-binding protein homologous protein expression in neuronal PC12 cells following tunicamycin-induced endoplasmic reticulum stress

BACKGROUND： Glucose-regulated protein 78 （GRP78）, a marker of endoplasmic reticulum stress, can prolong cell survival. Alternatively, CCAAT enhancer-binding protein homologous protein （CHOP）, a transcription factor specific for endoplasmic reticulum stress, can cause cell cycle arrest and cell apoptosis. OBJECTIVE： To study the protective effects of serum containing natural cerebrolysin on endoplasmic reticulum stress in tunicamycin-induced neuronal PC12 cells, and analyze the influence on GRP78 and CHOP expressions. DESIGN, TIME AND SETTING： A parallel controlled study was performed at the Institute of Integrated Western and Traditional Chinese Medicine, Shenzhen Hospital, Southern Medical University, between March 2006 and August 2008. MATERIALS： Adult Sprague-Dawley rats were perfused with natural Cerebrolysin aqueous extract （0.185 g/kg/d） to produce serum containing natural Cerebrolysin. Physiological saline was used to produce blank serum. PC12 cell line was provided by Shanghai Institute of Cell Biology, Chinese Academy of Science. Tunicamycin was provided by Sigma （St. Louis, USA）, and natural Cerebrolysin, containing ginseng, rhizoma gastrodiae, and gingko leaf （1：2：2）, by Shengzhen Institute of Integrated Western and Traditional Chinese Medicine. METHODS： PC12 cells were treated with DMEM culture media containing 10% blank serum （normal control group）, tunicamycin （1 μg/mL; model group）, and 5%, 10%, and 15% serum containing natural cerebrolysin and tunicamycin （1 μ g/mL; low-, moderate-, and high-dose serum containing natural cerebrotysin groups）, for 2 hours. MAIN OUTCOME MEASURES： PC12 cells were treated with tunicamycin for 48 hours after which apoptosis was measured using the TUNEL method to calculate apoptotic index. GRP78 expression was detected using immunocytochemistry. After 24 hours of treatment with tunicamycin, GRP78 and CHOP mRNA expressions were measured using RT-PCR. RESULTS： The apoptotic index and CHOP mRNA expression were in the model group and three cerebrolysin groups were significantly increased when compared to the normal control group （P 〈 0.05）. In contrast, GRP78 mRNA and protein expressions were significantly decreased （P 〈 0.05）. CONCLUSION： Serum containing natural cerebrolysin significantly reduced apoptosis in neuronal PC12 cells following tunicamycin-induced endoplasmic reticulum stress. These results may be related to an up-regulation of GRP78 expression and down-regulation of CHOP expression, both of which displayed dose-dependent effects.

The Man Who Organized Nature: The Life of Linnaeus by Gunnar Broberg

GunnarBroberg(1942–2022),a professor of history ideas and sciences at the Lund University in Sweden,has assembled and summarized virtually all of the contemporary documents relating to the life of Carl Linnaeus(1707–1778).This is therefore a fact-laden and definitive personal biography of the founder of our systems of plant and animal taxonomy.Linnaeus’childhood included much time in nature that forever provided him an experience background for the huge amount of plant and animal species he would encounter.In his early days,his country was in an era of poverty where“hordes of starving,homeless people drifted along the roads in the years when the harvest failed.”Linnaeus himself“...could lie awake all night as he lacked the money for evening meals when he was a student.”He inserted paper into his shoes to cover the holes on which he walked.