Estimation of N Absorption and Secretion by Digesta Exchange between 15N Labelled and Unlabelled Pigs

Abstract

Three female pigs (LW～30 kg) were fitted with re-entrant cannulas in the duodenum and the ileum and with bladder catheters. Animal No. 1 was labelled by continuous infusion of [¹⁵N]leucine via a catheter into the vena jugularis. After reaching a steady state in the level of endogenous N (4–5 d after beginning of the infusion) the digesta of the labelled animal No. 1 and the two unlabelled animals were exchanged in a 3 day experiment. During this time the course of transit rates of digesta, digesta N and ¹⁵N through duodenum and ileum as well as the proportion of endogenous N: exogenous N were estimated. Using these data it was possible to calculate the secretion and absorption rates of endogenous and exogenous N in the three segments of the digestive tract: mouth-duodenum, duodenum-ileum, ileum-anus and in addition the reabsorption (intestinal recycling) of the endogenous N during its passage through the gut could be computed.     

基于可信度量的信息系统故障快速诊断协议

随着计算机和互联网的飞速发展,信息系统的安全状况日趋复杂、混乱,应对信息系统故障在所难免,在实施PKI的信息系统中,设立权威可信第三方--度量中心,继承传统公钥密码体制优势,基于可信度量机制,设计度量存储协议、信息传输协议、快速诊断协议,目的是加强信息系统安全,对信息系统故障进行快速诊断,提高系统运行效率.     

基于可信平台的保护计算

随着计算机及网络技术的日趋成熟,全面解决计算机安全问题的要求就显得十分迫切。本文首先分析了已有的可信计算在解决计算机安全问题方面提供的一些手段,并指出其中存在的不足。之后提出保护计算的概念,具体阐述其机制和原理,最后论述保护计算作为一种对于可信计算的补充和完善对于解决现有计算机安全问题的所能提供的更优越的方案。     

一种软件源的可信管控模型设计

基于对目前可信计算信任链及度量基准值采集流程存在的问题,提出了软件源的可信管控模型,实现软件的安全认定、度量基准值统一计算采集以及可信第三方的集中管控,为软件的可信运行奠定了基础,降低了可信度量值采集工作的复杂度,对软件源的可信管控实施具有一定的指导意义。此外,进行了软件可信表征格式和基于可信表征的可信度量流程设计,将软件源的可信延伸至软件加载的可信和软件运行的可信,较大程度地提升了软件全生命周期的可信证明强度。     

基于可信计算技术的抗恶意代码攻击模型

通过对恶意代码攻击过程的分析,针对恶意代码攻击的类型手段,研究信任链传递技术、基于密码的安全隔离技术、多级安全访问控制技术以及安全管道域技术。信任链传递技术解决可信计算基不能被篡改的问题,基于密码的安全隔离技术解决可信计算基不能被绕过的问题,多级安全访问控制技术解决普通用户信息交互的完整性和保密性问题,安全管道域技术解决特权用户使用资源的范围问题。最后,在此基础上构建基于可信计算技术的抗恶意代码攻击模型,并分析该模型的效能。     

人工智能驱动的6G网络：智慧内生

为了满足智能适配人-机-物深度互联需求,第六代移动通信系统（6G）将基于全频谱、面向全场景、支撑全业务,其核心组成是智慧内生,也是驱动5G演进的趋势。探讨了人工智能驱动的6G智慧内生网络的特征与组成,描述了智慧内生网络的关键技术和产业应用现状,介绍了国内外相关进展和标准化工作,也对未来的挑战进行了展望。     

一种面向Portal认证的IPv6可信地址分配机制

随着网络规模的增长,对网络进行精细化管控变得尤为重要。在下一代互联网中将用户可信身份嵌入 IPv6 地址后缀形成可信地址,能够进一步提高网络行为的可追溯性。目前已有研究基于 Portal 认证配合DHCPv6将用户的身份信息嵌入用户终端的IPv6地址中,但是为了分配可信地址而改动的DHCPv6过程造成了机制对用户终端不透明,无法大规模部署。提出了一种面向Portal认证的IPv6可信地址分配机制,通过服务器信令交互配合软件定义网络（SDN）技术实现IPv6可信地址的间接分配,而且与地址分配方式无关。最后,实现了一个原型系统并在江苏南京电信现网机房评估了其可行性和性能,结果表明此机制在对终端透明的情况下仅带来很少的额外开销。     

Hierarchically Responsive Tumor-Microenvironment-Activated Nano-Artificial Virus for Precise Exogenous and Endogenous Apoptosis Coactivation

Targeting apoptotic pathways in tumor cells is recognized as a potent anticancer strategy. However, monotherapies that target a single apoptotic pathway often do not meet expectations and the nonspecific and uncontrolled activation of apoptotic pathways can overshadow potential application prospects. Here, a novel tumor-microenvironment-activated nano-artificial virus (TMAN) with hierarchically responsive capacity is fabricated and loaded with the plasmid encoding tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) and mitochondria-targeted red fluorescent phototoxic protein (KillerRed) simultaneously for precise and controllable exogenous and endogenous apoptosis coactivation. The inert TMAN is endowed with in vivo longevity and undergoes orderly acidity-triggered deshielding of a masking layer, enzyme-responsive charge-reversal, and oxidative stress-sensitive structural fragmentation in the tumor extra/intracellular microenvironment to exert precise tumor recognition, deep penetration, cellular internalization, rapid endosomes escape, and effective gene release ability, leading to the effective and tumor-specific delivery of payloads. Given the virtues of TMAN, a favorable collaboration of TRAIL-triggered exogenous apoptosis and mitochondria-targeted KillerRed induced endogenous apoptosis is achieved synchronously under the control of light irradiation, thus remarkably improving antitumor efficacy with minimal toxicity. Taken together, this strategy highlights the significance of exogenous and endogenous apoptosis coactivation in cancer treatments and offers a promising paradigm for precise exo/endogenous dual-augmented antitumor therapy.     

Trusted solution monitoring system based on ZigBee wireless sensor network

In the greenhouse environment,the concentration of nutrient solution was always ignored.At the same time,the core node coordinator of the ZigBee wireless monitoring system was easily compromised.A trusted solution monitoring system based on ZigBee wireless sensor network was designed and implemented.Firstly the hardware structure of sensor,router and coordinator was introduced.Then the processes of external voltage measurement and data cleaning were illustrated.For realizing the trusted boot of the coordinator,trusted u-boot to measure the integrity of some key files was designed.Experimental results show that the solution concentration data could be sent from each node to the monitoring computer and the remote terminal.At the same time,the trusted module of the coordinator can detect the captured coordinator node and warning.Therefore,the designed system has strong function and security.     

内生网络环境下具有异质连接费用的局部策略互动

考察内生网络环境下局中人之间的局部策略互动, 网络中的局中人只与直接邻居进行协同对策. 网络生成的过程中, 建立连接的费用是异质的~(具有两种水平), 与采取有效行动的局中人建立连接时执行高水平费用, 与采取风险占优行动的局中人建立连接时执行低水平费用. 在异质连接费用的情形下, 首次较为完整地给出了均衡网络的结构特性和局中人的行动选择, 并分析了费用参数对均衡结果的影响.