A modular approach for probe-fed and capacitively coupledmultilayered patch arrays

We present a modular technique for analyzing probe-fed, multilayered microstrip phased-array antennas. Each patch layer is assumed to be infinite in extent and represented by its generalized scattering matrix (GSM) with respect to a finite number of Floquet modes. For multilayer patch analysis, the individual GSMs are combined appropriately to yield the overall GSM of the structure. The individual GSM are obtained using the Galerkin method. The probe layer is represented by its generalized impedance matrix (GIM) which is deduced using Floquet modal analysis and the variational method. The GSMs and GIM are combined appropriately to yield the input impedance seen by the probe. Numerical results computed with this technique are shown to agree favorably with available data. Results for two-layered patch arrays and capacitively coupled patches are also presented     

Cdc34 and the F-box protein Met30 are required for degradation of the Cdk-inhibitory kinase Swe1

Ubiquitin-mediated proteolysis controls the abundance of many cell cycle regulatory proteins. Recent work in Saccharomyces cerevisiae suggests that a complex consisting of Cdc53, Skp1, and a third component known as an F-box protein (termed SCF) in combination with Cdc34 specifically targets regulatory proteins for degradation, and that substrate specificity is likely to be mediated by the F-box subunit. A screen for genetic interactions with a cdc34 mutation yielded MET30, which encodes an F-box protein. MET30 is an essential gene required for cell cycle progression and met30 mutations interact genetically with mutations in SCF components. Furthermore, physical interactions between Met30, Cdc53, Cdc34, and Skp1 in vivo provide evidence for an SCFMet30 complex. We demonstrate the involvement of Met30 in the degradation of the Cdk-inhibitory kinase Swe1. Swe1 is stabilized in met30 mutants and GST-Met30 pull-down experiments reveal that Met30 specifically binds Swe1 in vivo. Furthermore, extracts prepared from cdc34 or met30 mutants are defective in polyubiquitination of Swe1. Taken together, these data suggest that SCF-mediated proteolysis may contribute to the regulation of entry into mitosis. Our data, in combination with previously published results, also provide evidence for distinct SCF complexes in vivo and support the idea that their F-box subunits mediate SCF substrate specificity.     

Unfolding mechanism of rubredoxin from Pyrococcus furiosus

As part of our studies on the structural and dynamic properties of hyperthermostable proteins, we have investigated the unfolding pathways of the small iron-sulfur protein rubredoxin from Pyrococcus furiosus (RdPf) at pH 2. Unfolding has been initiated by temperature jump, triggered by manual mixing of a concentrated protein solution into a thermally preequilibrated buffer. The process has been followed in real time by absorption, tryptophan fluorescence emission, and far-UV circular dichroism. Unlike the case of the mesophilic rubredoxin from Clostridium pasteurianum (RdCp), RdPf displays a complex unfolding kinetics, pointing to the formation of at least three intermediates. All of the steps, including the one involving metal ion release, are extremely slow. However, hydrophobic core relaxation--not Fe3+ loss--is rate-determining for RdPf unfolding. This clearly rules out the fact that Fe3+ is solely responsible for the kinetic stability of RdPf. Results have been discussed in terms of sequential vs parallel pathways, and the possible role of irreversible phenomena has been taken into consideration. Aggregation does not appear to play a significant role in the observed kinetic complexities. According to a proposed sequential mechanism, partial release of secondary structure elements precedes iron loss, which is then followed by further loss of beta-sheet content and, finally, by hydrophobic relaxation. Although the main features of the RdPf unfolding mechanism remain substantially unchanged over the experimentally accessible temperature range, final hydrophobic relaxation gets faster, relative to the other events, as the temperature is decreased. A qualitative assessment of the unfolding activation parameters suggests that this arises from the very low activation energies (Ea) that characterize this step.     

Distinction between enzymically and chemically catalyzed interesterification

The 1,3-specific lipase-catalyzed interesterified fats were distinguished from chemically catalyzed products by the fatty acids in the 2-position. The fatty acid contents in the 2-position of the 1,3-lipase-catalyzed and the original triglycerides were similar but different from that of chemically interesterified fat. Also, the saturated-to-unsaturated fatty acid ratio in the 2-monoglycerides was lower for the 1,3-specific lipase-catalyzed interesterified fats than for the corresponding chemical products.     

苏州市景观水体表观污染类型识别及特征指标筛选

为解决表观污染成因的问题,以苏州市区河网为主要研究对象,采集796个数据样本,对景观水体的表观污染类型进行划分界定,并通过对数据样本的统计分析,探究水体表观污染类型和水质指标之间的关系。结果表明:氧化还原电位、溶解氧、叶绿素a、高锰酸盐指数和浊度对不同污染类型的水体具有很好的区分度,可作为主要特征指标;景观水体可分为有机主导型、无机主导型、营养主导型和混合型4种表观污染类型;不同表观污染水体判别的优先次序为有机主导型、无机主导型、营养主导型、混合型。     

采用工作量证明共识机制的区块链中挖矿攻击者间的“鲶鱼效应”

近年来,采用工作量证明共识机制(Proof of Work,PoW)的区块链被广泛地应用于以比特币为代表的数字加密货币中.自私挖矿攻击(Selfish mining)等挖矿攻击(Mining attack)策略威胁了采用工作量证明共识机制的区块链的安全性.在自私挖矿攻击策略被提出之后,研究者们进一步优化了单个攻击者的挖矿攻击策略.在前人工作的基础上,本文提出了新颖的两阶段挖矿攻击模型,该模型包含拥有单攻击者的传统自私挖矿系统与拥有两个攻击者的多攻击者系统.本文的模型同时提供了理论分析与仿真量化分析,并将两个攻击者区分为内部攻击者与外部攻击者.通过引入内部攻击者与外部攻击者的概念,本文指出传统自私挖矿系统转化为多攻击者系统的条件.本文进一步揭示了在多攻击者系统中两个攻击者将产生竞争并面临着“矿工困境”问题.攻击者间的竞争可被总结为“鲶鱼效应”:外部攻击者的出现导致内部攻击者的相对收益下降至多67.4%,因此内部攻击者需要优化攻击策略.本文提出了名为部分主动发布策略的全新挖矿攻击策略,相较于自私挖矿策略,该策略是半诚实的攻击策略.在特定场景下,部分主动发布策略可以提高攻击者的相对收益并破解攻击者面临的“矿工困境”问题.     

手机数据存储和恢复方法研究

文章以手机数据存储和恢复为研究目的,对目前主流的手机操作系统,即Java非智能手机操作系统、塞班非智能与智能手机操作系统,分别将其数据的删除和恢复等进行对比分析,总结数据存储结构和存储方式,归纳手机数据恢复的方法,以期有效解决日常数据丢失等相关问题。