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Origin of the presence/absence variation of the LTIA1/LTIA2 mini-ribonucleaseⅢgenes required for low-temperature growth in rice
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作者 Jing Yang Yu Peng +5 位作者 Limin Mi Aiqing Sun Ping Li Yan Wang Yi Zhang Sheng Teng 《The Crop Journal》 SCIE CSCD 2024年第5期1459-1470,共12页
A rice low temperature-induced albino variant was determined by the recessive ltia1 and ltia2 genes.LTIA1 and LTIA2 encode highly conserved mini-ribonucleasesⅢlocated in chloroplasts and expressed in aerial parts of ... A rice low temperature-induced albino variant was determined by the recessive ltia1 and ltia2 genes.LTIA1 and LTIA2 encode highly conserved mini-ribonucleasesⅢlocated in chloroplasts and expressed in aerial parts of the plant.At low temperature,LTIA1 and LTIA2 redundantly affect chlorophyll levels,non-photochemical quenching,photosynthetic quantum yield of PSⅡand seedling growth.LTIA1 and LTIA2 proteins are involved in splicing of atp F and the biogenesis of 16S and 23S rRNA in chloroplasts.Presence/absence variation of LTIA1,the ancestral copy,was found only in japonica but that of LTIA2 in all rice subgroups.Accessions with LTIA2 presence tended to be distributed more remote from the equator compared to those with LTIA2 absence.LTIA2 duplicated from LTIA1 at the early stage of divergence of the AA genome Oryza species but deleted againin O.nivara.In cultivated rice,absence of LTIA2 is derived from O.nivara.LTIA1 absence occurred more recently in japonica. 展开更多
关键词 RICE Low temperature induced albino Mini-RNaseⅢ presence/absence variations Evolution
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Presence–absence surveys of prey and their use in predicting leopard (Panthera pardus) densities: a case study from Armenia 被引量:1
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作者 Igor G.KHOROZYAN Alexander G.MALKHASYAN Alexei V.ABRAMOV 《Integrative Zoology》 SCIE CSCD 2008年第4期322-332,共11页
It is important to predict how many individuals of a predator species can survive in a given area on the basis of prey sufficiency and to compare predictive estimates with actual numbers to understand whether or not k... It is important to predict how many individuals of a predator species can survive in a given area on the basis of prey sufficiency and to compare predictive estimates with actual numbers to understand whether or not key threats are related to prey availability.Rugged terrain and low detection probabilities do not allow for the use of traditional prey count techniques in mountain areas.We used presence–absence occupancy modeling and camera-trapping to estimate the abundance and densities of prey species and regression analysis to predict leopard(Panthera pardus)densities from estimated prey biomass in the mountains of the Nuvadi area,Meghri Ridge,southern Armenia.The prey densities were 12.94±2.18 individuals km–2 for the bezoar goat(Capra aegagrus),6.88±1.56 for the wild boar(Sus scrofa)and 0.44±0.20 for the roe deer(Capreolus capreolus).The detection probability of the prey was a strong function of the activity patterns,and was highest in diurnal bezoar goats(0.59±0.09).Based on robust regression,the estimated total ungulate prey biomass(720.37±142.72 kg km–2)can support a leopard density of 7.18±3.06 individuals 100 km–2.The actual leopard density is only 0.34 individuals 100 km–2(i.e.one subadult male recorded over the 296.9 km2),estimated from tracking and camera-trapping.The most plausible explanation for this discrepancy between predicted and actual leopard density is that poaching and disturbance caused by livestock breeding,plant gathering,deforestation and human-induced wild fires are affecting the leopard population in Armenia. 展开更多
关键词 ARMENIA LEOPARD linear regression presence–absence prey.
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The Relationship between Father-Love Absence and Loneliness:Based on the Perspective of the Social Functionalist Theory and the Social Needs Theory
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作者 Yaping Zhou He Zhong +1 位作者 Xiaojun Li Yanhui Xiang 《International Journal of Mental Health Promotion》 2024年第2期139-148,共10页
Fathers play an important role in adolescents’development,which is significant for their development and influences their mental health,including feeling of loneliness.However,the effects and mechanisms of father-lov... Fathers play an important role in adolescents’development,which is significant for their development and influences their mental health,including feeling of loneliness.However,the effects and mechanisms of father-love absence on individual loneliness are not clear.Based on the social functionalist theory and the social needs theory,this study examines the influence of individual fatherlove absence on loneliness and its underlying mechanisms.A questionnaire survey was administered to 319 junior high school students and 1,476 high school students.The results showed that adolescents with father-love absence had higher levels of loneliness,and that father-love absence affected loneliness levels through mediating pathways of individual gratitude,peer relationships,and gratitude to peer relationships.This study not only confirms the negative effects of father-love absence on adolescents’loneliness,but also explains the mediate roles of individual gratitude and peer relationships.It enriches the theoretical system related to family education and has important theoretical and practical implications for further interventions on adolescents’mental health from the perspective of fatherless parenting. 展开更多
关键词 Father-love absence LONELINESS GRATITUDE peer relationships
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How Presence Affects College Students’Online Learning Outcomes:Unveiling Its Underlying Mechanism
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作者 Pan Li Xu Songhe 《Contemporary Social Sciences》 2024年第4期68-87,共20页
Over the past few years,China’s higher education institutions have experienced remarkable growth in online teaching.However,it remains uncertain whether and how the sense of presence perceived by students affects the... Over the past few years,China’s higher education institutions have experienced remarkable growth in online teaching.However,it remains uncertain whether and how the sense of presence perceived by students affects their online learning outcomes when teachers use online teaching media for communication.This sense specifically pertains to the extent to which students perceive themselves as“real persons”and establish connections with others.Therefore,this study constructs a conceptual model elucidating the impact of presence on students’online learning outcomes and empirically examines the mechanism through which three types of presence influence students’online learning.The test results of the structural equation modeling(SEM)indicate that:(a)teaching presence,social presence,and cognitive presence all exhibit significantly positive outcomes on students’online learning outcomes;(b)these three types of presence can also indirectly and positively influence students’online learning outcomes through the mediating effect of flow experience and learning satisfaction;and(c)flow experience and learning satisfaction play a sequential mediating role in the process by which presence impacts students’online learning outcomes.We hope that the relevant research findings may contribute to unveiling the“black box”of the impact of presence on students’online learning outcomes and offer valuable insights for college educators to overcome online teaching constraints and enhance online teaching quality. 展开更多
关键词 presence online learning outcomes flow experience learning satisfaction
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IN VITRO CYTOGENETIC EFFECTS OF AGRIZIM AND BAYLETON ON HUMAN LYMPHOCYTES IN THE PRESENCE AND ABSENCE OF METABOLIC ACTIVATION
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作者 Dharambir K.Sandhu JaiRupSingh 《癌变.畸变.突变》 CAS CSCD 1991年第S1期157-157,共1页
Agrizim and bayleton,two commonly usedagricultural fungicides in India,wereinvestigated for their genotoxicpotentialities on cultured humanlymphocytes by studying chromosomalaberrations and sister chromatid exchangesi... Agrizim and bayleton,two commonly usedagricultural fungicides in India,wereinvestigated for their genotoxicpotentialities on cultured humanlymphocytes by studying chromosomalaberrations and sister chromatid exchangesin the presence and absence of 展开更多
关键词 SISTER EXOGENOUS absence India cultured exchanges elevation CYTOTOXIC BREAKS doses
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Spatial Multi-Presence System to Increase Security Awareness for Remote Collaboration in an Extended Reality Environment
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作者 Jun Lee Hyun Kwon 《Intelligent Automation & Soft Computing》 SCIE 2023年第7期369-384,共16页
Enhancing the sense of presence of participants is an important issue in terms of security awareness for remote collaboration in extended reality.However,conventional methods are insufficient to be aware of remote sit... Enhancing the sense of presence of participants is an important issue in terms of security awareness for remote collaboration in extended reality.However,conventional methods are insufficient to be aware of remote situations and to search for and control remote workspaces.This study pro-poses a spatial multi-presence system that simultaneously provides multiple spaces while rapidly exploring these spaces as users perform collaborative work in an extended reality environment.The proposed system provides methods for arranging and manipulating remote and personal spaces by creating an annular screen that is invisible to the user.The user can freely arrange remote participants and their workspaces on the annular screen.Because users can simultaneously view various spaces arranged on the annular screen,they can perform collaborative work while simultaneously feeling the presence of multiple spaces and can be fully immersed in a specific space.In addition,the personal spaces where users work can also be arranged through the annular screen.According to the results of the performance evaluations,users participating in remote collaborative works can visualize the spaces of multiple users simultaneously and feel their presence,thereby increasing their understanding of the spaces.Moreover,the proposed system reduces the time to perform tasks and gain awareness of the emergency in remote workspaces. 展开更多
关键词 Extended reality spatial presence multi presence security awareness
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Congenital Absence of Pericardium:The Largest Systematic Review in the Field on 247 Worldwide Cases(1977-Now)
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作者 Pier Paolo Bassareo Aurelio Secinaro +4 位作者 Paolo Ciliberti Massimo Chessa Marco Alfonso Perrone Kevin Patrick Walsh Colin Joseph Mcmahon 《Congenital Heart Disease》 SCIE 2023年第6期595-610,共16页
Background:Congenital absence of pericardium(CAP),also known as pericardial agenesis,represents an uncommon cardiac abnormality and mostly incidental finding.It can be subdivided into complete and partial(left or righ... Background:Congenital absence of pericardium(CAP),also known as pericardial agenesis,represents an uncommon cardiac abnormality and mostly incidental finding.It can be subdivided into complete and partial(left or right-sided)forms.Because of its infrequency,just case reports and a few case series have been released so far.This paper represents the largest systematic review in the field.Nine features(age at diagnosis,type,gender,clinical presentation,electrocardiography,imaging(ultrasounds,CT/MRI),concomitant cardiac defects,and outcome)were analysed.Methods:The electronic database PubMed was investigated from its establishment up to July 15th,2023.Just case reports and case series were included.Animal studies,papers that were not in English,Spanish,and Italian,and those manuscripts not reporting at least seven of the nine analysed features.were ruled out.The analysed data were reported mostly in terms of percentage.Results:One hundred eighty studies were included encompassing 247 patients.More than half of reviewed CAP cases were in males(63.2%).The mean age at diagnosis was 31.8±19.3 years;a range of 32 weeks of gestation-81 years).23.5%of the patients did not report any symptoms.The most common clinical presentations were chest pain(35.2%)and dyspnoea(29.2%).The most commonly seen ECG changes were right axis deviation(28.7%)and right bundle branch block(23.9%).CAP was suspected or diagnosed by echocardiography in 20.1%of cases.The diagnosis was made by CT and/or MRI in 61.9%of cases.CAP was left-sided in 71.2%,complete in 23.1%,and right-sided in 5.7%.A concomitant congenital heart defect was found in 22.7%,especially in the form of atrial septal defect(6.5%)and patency of ductus arteriosus(2.8%).The pericardial repair was required in 12.9% of the incomplete forms of the disease.Never did the complete form require surgical correction.The outcome appeared favourable in the vast majority of cases,with just 18 deaths(7.3%).Discussion:The main limitation of this systematic review is that it is based just on case reports and case series,due to the lack of large studies on CAP.However,it represents the largest analysis in the field.Due to the rarity of CAP establishing an International Registry is recommended. 展开更多
关键词 Congenital absence pericardium pericardial agenesis ELECTROCARDIOGRAPHY ECHOCARDIOGRAPHY computed tomography cardiac magnetic resonance imaging
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Typical Zollinger-Ellison syndrome-atypical location of gastrinoma and absence of hypergastrinemia:A case report and review of literature
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作者 Jin-Ming Zhang Chu-Wei Zheng +4 位作者 Xiao-Wen Li Zhi-Yun Fang Mu-Xin Yu Hai-Yan Shen Xia Ji 《World Journal of Clinical Cases》 SCIE 2023年第26期6223-6230,共8页
BACKGROUND Zollinger–Ellison syndrome(ZES)results from hypersecretion of gastrin from pancreatic or duodenal neuroendocrine tumors,commonly referred to as gastrinomas.The high levels of gastrin lead to a typical pres... BACKGROUND Zollinger–Ellison syndrome(ZES)results from hypersecretion of gastrin from pancreatic or duodenal neuroendocrine tumors,commonly referred to as gastrinomas.The high levels of gastrin lead to a typical presentation involving watery diarrhea and multiple ulcers in the duodenum.Here,we have presented the rare case of a patient with ZES and absence of hypergastrinemia as well as an atypical location of gastrinoma.CASE SUMMARY A 72-year-old woman presented with the typical clinical manifestations of ZES,including upper abdominal pain,significant watery diarrhea,and acidic liquid vomitus.Surprisingly,however,she did not have an increased level of serum gastrin.In addition,there was no evidence of gastrinoma or any other ulcerogenic tumor.Esophagogastroduodenoscopy was conducted to examine the upper digestive tract.Revised diagnoses were considered,and an individualized treatment plan was developed.The patient responded to antacid medication while experiencing intermittent,recurring bouts of ZES.18F-AlF-NOTAoctreotide positron emission tomography(18F-OC PET)/computed tomography(CT)helped locate the tumor.Postoperative pathology and immunohistochemistry results suggested that the tumor was a gastrinoma located at an unconventional site.CONCLUSION This present case study demonstrates the possibility of ZES-like manifestation in patients with absence of hypergastrinemia.18F-OC PET/CT is a relatively new imaging technique that can be applied for diagnosing even tiny gastrinomas that are atypical in terms of location. 展开更多
关键词 Zollinger-Ellison syndrome GASTRINOMA Atypical location absence of hypergastrinemia 18F-AlF-NOTAoctreotide Case report
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Beyond Video Quality:Evaluation of Spatial Presence in 360-Degree Videos
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作者 ZOU Wenjie GU Chengming +2 位作者 FAN Jiawei HUANG Cheng BAI Yaxian 《ZTE Communications》 2023年第4期91-103,共13页
With the rapid development of immersive multimedia technologies,360-degree video services have quickly gained popularity and how to ensure sufficient spatial presence of end users when viewing 360-degree videos become... With the rapid development of immersive multimedia technologies,360-degree video services have quickly gained popularity and how to ensure sufficient spatial presence of end users when viewing 360-degree videos becomes a new challenge.In this regard,accurately acquiring users’sense of spatial presence is of fundamental importance for video service providers to improve their service quality.Unfortunately,there is no efficient evaluation model so far for measuring the sense of spatial presence for 360-degree videos.In this paper,we first design an assessment framework to clarify the influencing factors of spatial presence.Related parameters of 360-degree videos and headmounted display devices are both considered in this framework.Well-designed subjective experiments are then conducted to investigate the impact of various influencing factors on the sense of presence.Based on the subjective ratings,we propose a spatial presence assessment model that can be easily deployed in 360-degree video applications.To the best of our knowledge,this is the first attempt in literature to establish a quantitative spatial presence assessment model by using technical parameters that are easily extracted.Experimental results demonstrate that the proposed model can reliably predict the sense of spatial presence. 展开更多
关键词 virtual reality quality assessment omnidirectional video spatial presence
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The Contribution Margin due to a Limiting Factor in the Presence of Several Sales Options: Actuality Is Not Always As It Appears at the Beginning of the Analysis
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作者 Maria Silvia Avi 《Journal of Modern Accounting and Auditing》 2023年第1期1-22,共22页
The analysis of company data useful for economic decisions,if not interpreted in an overall view of the company situation,can lead to wrong conclusions.This is the case when a company has to choose between several sal... The analysis of company data useful for economic decisions,if not interpreted in an overall view of the company situation,can lead to wrong conclusions.This is the case when a company has to choose between several sales options for one or more products in the presence of a limiting factor.The continuation of the investigation often denies the initial analysis.Not everything is as it appears,therefore,at the beginning of the deepening of the data useful for economic decisions.As it is well known,the choices of profitability concerning the planning of the sale of company products take place,at least in the majority of cases,through the determination of the contribution margin,i.e.the profitability margin connected to the individual goods/services sold by the companies(selling price net of variable costs).The contribution margin can be determined with four objectives:(1)Determination of the yield of the single product,net of variable costs only.In this case,the margin defines unitary,from net product yield to unitary contribution margin.(2)Determination of the return on total sales of an individual product,net of variable costs.In this hypothesis,reference is made to the first level(or gross)contribution margin.(3)Determination of the ability of the individual product to contribute to the coverage of fixed costs common to the company.This margin is determined net of special product variable and fixed costs.This aggregate is defined as a Level II(or semi-gross)margin.(4)Determination of the useful value in the planning choices in case of presence of scarce productive factors.In this case,it must identify the so-called unitary margin for low factor.Here we will only deal with the problem of the use of the contribution margin in the presence of rare factors.To complete the analysis,below are some very brief considerations regarding,respectively,the unitary,level I,and level II contribution margin in order to better understand where the problem of the most convenient choice of income is located in the event of the presence of rare production factors,especially in an environment characterized by a plurality of sales options. 展开更多
关键词 contribution margin unit contribution margin first level contribution margin second level contribution margin Unit Scarce factor contribution margin Unit Scarce factor contribution margin in the presence of a plurality of sales options profit
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一种新的Presence建模方法 被引量:2
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作者 沈奇威 廖建新 《高技术通讯》 CAS CSCD 北大核心 2007年第2期124-129,共6页
在分析Presence信息特征的基础上,提出了Presence模型的建模需求和功能目标,并指出:信息共享、隐私保护以及信息融合要求对信息提供一致的管理方式,可通过建立Presence信息模型来解决这一问题,信息模型的建立应该直观和易用。根据... 在分析Presence信息特征的基础上,提出了Presence模型的建模需求和功能目标,并指出:信息共享、隐私保护以及信息融合要求对信息提供一致的管理方式,可通过建立Presence信息模型来解决这一问题,信息模型的建立应该直观和易用。根据建模需求对适用的建模方法进行了比较,建立了一种新的面向普通应用开发者的混合建模方法,结合图形化建模和本体建模的优点,在建模过程引入了模型驱动结构(MDA)方法和工程化思想,标准化的表达方式和规范的建模步骤保证了建模的质量。 展开更多
关键词 presence 建模方法 模型驱动结构(MDA) 本体
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面向移动互联网的Presence/IM机制研究 被引量:7
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作者 杨海波 王默涵 +1 位作者 贾正锋 卜立平 《小型微型计算机系统》 CSCD 北大核心 2015年第11期2549-2553,共5页
以Presence/IM为代表的OTT业务具有实时在线、随时随地沟通的便利性成了移动互联网时代的应用热点.在当前电信标准体系中,Presence/IM实现机制分为SIMPLE和XMPP两大类,但这两类协议制定较早,在流量、功耗及传输上都没考虑移动互联网的特... 以Presence/IM为代表的OTT业务具有实时在线、随时随地沟通的便利性成了移动互联网时代的应用热点.在当前电信标准体系中,Presence/IM实现机制分为SIMPLE和XMPP两大类,但这两类协议制定较早,在流量、功耗及传输上都没考虑移动互联网的特点,本文将在分析SIMPLE和XMPP协议的基础上,提出一种基于订阅/发布模型的移动互联网Presence/IM机制并给出具体实现,并重点阐述多终端同时在线情况时的消息路由机制.最后将本文提出的协议与SIMPLE和XMPP进行了对比分析. 展开更多
关键词 即时通信 状态呈现 移动互联网 MQTT 通信机制
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基于SIP协议的Presence服务的研究 被引量:1
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作者 陈雪莲 李中跃 《无线互联科技》 2012年第10期126-126,共1页
Presence服务是多媒体会议、即时消息等网络应用中的一项重要服务。SIP协议可以很好的作为一种Presence协议来实现presence服务,本文通过SIP协议的SUBSCRIBE、NOTIFY和扩展的PUBLISH方法,使用SIP协议的事件通知机制设计了一个基于SIP协... Presence服务是多媒体会议、即时消息等网络应用中的一项重要服务。SIP协议可以很好的作为一种Presence协议来实现presence服务,本文通过SIP协议的SUBSCRIBE、NOTIFY和扩展的PUBLISH方法,使用SIP协议的事件通知机制设计了一个基于SIP协议的Presence服务系统。 展开更多
关键词 presence PA SIP PUA
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3G网络中的Presence业务 被引量:2
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作者 杨红梅 《电信网技术》 2006年第10期13-15,共3页
在介绍Presence业务总体特征的基础上,通过业务场景说明业务的具体应用,简单阐述了Presence业务的网络结构,最后介绍了目前国内外研究情况以及展望Presence业务发展前景。
关键词 presence业务 presence 观察者
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Presence服务中授权机制的研究
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作者 叶自宁 《计算机与现代化》 2012年第1期115-118,共4页
随着IP通信业务的发展,Presence业务在通信系统中起着越来越重要的作用。用户发布的Presence信息包含越来越多的私人信息和敏感信息,Presence服务器需要经过发布者授权后才能把Presence信息发布给观察者。针对授权规则问题IETF提出了两... 随着IP通信业务的发展,Presence业务在通信系统中起着越来越重要的作用。用户发布的Presence信息包含越来越多的私人信息和敏感信息,Presence服务器需要经过发布者授权后才能把Presence信息发布给观察者。针对授权规则问题IETF提出了两种解决方法:Watcher Info机制和XCAP机制。本文主要介绍基于SIMPLE的Presence服务系统中两种机制的实现方法,对比分析两种机制的优缺点,在此基础上分析两者的发展前景。 展开更多
关键词 presence 授权规则 Watcher INFO XCAP
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基于P2P-SIP的Presence业务
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作者 熊景松 林涛 +1 位作者 吕振肃 赵志军 《微计算机应用》 2008年第6期6-11,共6页
即时通信作为一种通信形式受大众喜爱。本文简单说明了当前即时消息软件的不足,通过分析标准SIP协议的技术优势和P2P网络的良好特性。提出了较为稳定、安全、易于扩充的Presence业务模型。
关键词 即时通信 presence业务 P2P—SIP
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Robotic Electrotactile Feedback Glove for Tele Presence System 被引量:1
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作者 张红芬 李科杰 +1 位作者 艾俊波 申延涛 《Journal of Beijing Institute of Technology》 EI CAS 2000年第3期318-323,共6页
Progress is described regarding the development of a new electrotactile feedback glove designed for application to dexterous robot. The sensitivity of operator's finger against electrical stimulus pulse is conside... Progress is described regarding the development of a new electrotactile feedback glove designed for application to dexterous robot. The sensitivity of operator's finger against electrical stimulus pulse is considered. It is found that frequency, duty ratio, and voltage amplitude of electrical stimulus pulse determine the sensitivity of finger. The effects of materials, sizes, arrangements and shapes of electrodes on sensitivity of finger are analyzed. Finally, the tactile tele presence system is designed to experimentally confirm that the robot with electrotactile feedback glove can manipulate dexterous robotic multi fingered hand and identify and classify three sorts of objects. 展开更多
关键词 electrotactile feedback data glove tele presence ROBOT
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基于IMS的Presence服务器的设计及实现
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作者 程新丽 《科技创业月刊》 2008年第12期188-189,191,共3页
介绍了IMS中Presence业务体系架构,以及在该架构中的Presence服务器的位置和功能要求,并提出了一个设计方案,介绍了实现过程中的关键问题的解决思路和实现算法。
关键词 IP多媒体子系统 呈现业务 呈现业务服务器
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IMS中基于Presence生活导航系统的设计与实现 被引量:1
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作者 贾丹丹 朱晓民 +2 位作者 荀兆勇 杨军 廖建新 《计算机系统应用》 2008年第10期11-14,共4页
生活导航系统LPS(Life Presence System)是将Presence的机制扩展到呈现日常生活相关的事物状态变化的应用中,并提供交互式的操作完成用户行为的导航。文章描述了生活导航系统的主要应用场景以及应用的前景,介绍了IMS(IP Multimedia Subs... 生活导航系统LPS(Life Presence System)是将Presence的机制扩展到呈现日常生活相关的事物状态变化的应用中,并提供交互式的操作完成用户行为的导航。文章描述了生活导航系统的主要应用场景以及应用的前景,介绍了IMS(IP Multimedia Subsystem)中基于Presence业务能力的生活导航系统的网络结构以及功能,提出了LPS系统的详细实现方案,并对系统实现的关键技术进行了分析。 展开更多
关键词 生活导航系统 IMS presence 业务能力 内容服务器 XCAP
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基于SIP协议的Presence/IM技术研究与进展 被引量:1
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作者 兰国亮 杨海波 +2 位作者 孙建伟 贾正锋 梁宇 《小型微型计算机系统》 CSCD 北大核心 2014年第11期2440-2444,共5页
随着互联网的迅速发展和IMS系统的逐渐成熟,基于SIP协议的Presence/IM业务研究和应用日趋增多.Presence/IM业务的需求带来了一系列的问题,而标准的制定工作更是首当其冲.IETF提供了很多规范来支持基于SIP协议的Presence/IM功能,这些规... 随着互联网的迅速发展和IMS系统的逐渐成熟,基于SIP协议的Presence/IM业务研究和应用日趋增多.Presence/IM业务的需求带来了一系列的问题,而标准的制定工作更是首当其冲.IETF提供了很多规范来支持基于SIP协议的Presence/IM功能,这些规范被称为SIMPLE.本文详细分析了SIMPLE所涉及的规范和标准,并结合SIP事件扩展和IMPP协议总结了SIMPLE提供的具体功能,同时按照规范的功能进行了分类,并说明了这些规范之间的关系.论文还讨论了Presence/IM技术未来的研究方向和发展趋势. 展开更多
关键词 SIMPLE 状态呈现 订阅/通知 XCAP 即时通信 MSRP
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