Algebraic properties of cryptosystem PGM

In the late 1970s Magliveras invented a private-key cryptographic system calledPermutation Group Mappings (PGM). PGM is based on the prolific existence of certain kinds of factorization sets, calledlogarithmic signatures, for finite permutation groups. PGM is an endomorphic system with message space ℤ_|G| for a given finite permutation groupG. In this paper we prove several algebraic properties of PGM. We show that the set of PGM transformations ℐ _G is not closed under functional composition and hence not a group. This set is 2-transitive on ℤ_|G| if the underlying groupG is not hamiltonian and not abelian. Moreover, if the order ofG is not a power of 2, then the set of transformations contains an odd permutation. An important consequence of these results is that the group generated by the set of transformations is nearly always the symmetric group ℒ_|G|. Thus, allowing multiple encryption, any permutation of the message space is attainable. This property is one of the strongest security conditions that can be offered by a private-key encryption system. S. S. Magliveras was supported in part by NSF/NSA Grant Number MDA904-82-H0001, by U.S. West Communications, and by the Center for Communication and Information Science of the University of Nebraska.     

概率图模型及其图像与视频应用研究

概率图模型及其应用作为一个具有挑战性的研究领域目前已成为一个新的研究热点。概率图模型为解决智能信息领域的不确定性问题提供了重要途径。尽管目前概率图模型还处于不断发展之中,但近年来基于概率图模型的图像和视频智能信息处理的应用研究受到人们的关注,出现了许多有效的算法,这些算法为解决一些传统的图像和视频智能信息处理问题提供了新的途径。本文首先对概率图模型的3种重要表现形式、特性和主要技术进行了分析和讨论,在此基础上,以概率图模型在图像和视频中的应用为线索,对目前基于概率图模型的图像和视频智能信息处理的主要技术进行了概述和比较研究;最后对概率图模型所存在的一些问题及进一步的发展进行了展望。     

基于PGM模型的可用带宽度量算法评估

探测间隔模型(PGM)是负载小、速度快的可用带宽度量方法,但目前针对PGM的算法还缺乏系统、深入的评估。针对上述问题分析影响PGM算法精度的主要因素,提出端对端路径可用带宽的新型分类方法,选取PGM模型中较典型的Spruce和IGI算法,通过理论推导和仿真测试,评估不同背景流量类型等因素对算法精度的影响,为改进PGM模型的算法设计、提高算法精度提供参考。     

Pt族金属在加压氰化浸出过程中的行为探讨

对加压氰化浸出过程Pt族金属(Pt,Pd,Rh)行为的研究表明,Pt族金属氰化浸出率的顺序为Pd>Pt>Rh,而相应氰配合物高温下稳定性顺序为Rh≈Pt>Pd浸出过程中的行为规律实际上反映的是表面态Pt族金属的化学反应活性顺序,也即金属的原子态稳定性和金属键强度两种变化规律的综合表现,而Pt族金属氰配合物高温稳定性可以由“重Pt族配合物比相应结构的轻Pt族配合物的热力学稳定性更大,动力学惰性更高”以及金属氰配离子反应活性得到解释。     

“双湿法”从汽车失效催化剂中回收铂族金属及有价金属

通过常规湿法浸出-预处理-再次湿法浸出的"双湿法"工艺,综合回收多种汽车失效催化剂(SAC)中的铂族金属(PGMs)及有价金属镧、铈和锆。采用X射线荧光法、分光光度法、ICP-AES法、扫描电镜及X射线衍射进行分析表征。结果表明,"双湿法"工艺可使铂、钯、铑的浸出率比常规湿法浸出分别提高了7%~30%、2%、18%~21%,PGMs的回收率大于95%,浸出渣率为30%~35%;镧、铈和锆同时得到有效回收,其中铈、锆的综合回收率大于92%。     

Next-Generation Sequencing Workflow for NSCLC Critical Samples Using a Targeted Sequencing Approach by Ion Torrent PGM? Platform

Next-generation sequencing (NGS) is a cost-effective technology capable of screening several genes simultaneously; however, its application in a clinical context requires an established workflow to acquire reliable sequencing results. Here, we report an optimized NGS workflow analyzing 22 lung cancer-related genes to sequence critical samples such as DNA from formalin-fixed paraffin-embedded (FFPE) blocks and circulating free DNA (cfDNA). Snap frozen and matched FFPE gDNA from 12 non-small cell lung cancer (NSCLC) patients, whose gDNA fragmentation status was previously evaluated using a multiplex PCR-based quality control, were successfully sequenced with Ion Torrent PGM™. The robust bioinformatic pipeline allowed us to correctly call both Single Nucleotide Variants (SNVs) and indels with a detection limit of 5%, achieving 100% specificity and 96% sensitivity. This workflow was also validated in 13 FFPE NSCLC biopsies. Furthermore, a specific protocol for low input gDNA capable of producing good sequencing data with high coverage, high uniformity, and a low error rate was also optimized. In conclusion, we demonstrate the feasibility of obtaining gDNA from FFPE samples suitable for NGS by performing appropriate quality controls. The optimized workflow, capable of screening low input gDNA, highlights NGS as a potential tool in the detection, disease monitoring, and treatment of NSCLC.     

俄罗斯诺里尔斯克镍矿冶公司北极圈分公司镍-铜-铂族金属矿山

俄罗斯诺里尔斯克镍矿冶公司((ГМК ?Норильский Никель?)北极圈分公司镍-铜-铂族金属矿山是世界上最大的钯生产矿山,它具有世界上最丰富的镍和铂族金属资源。截至2011年底,该矿山证实的和概略的矿石储量为3.39亿t,其中含1.33% Ni、2.26% Cu、5..38g/t Pd和1.42g/t Pt。测定的和指示的矿石资源量为13.8亿t,其中含0.57 Ni、1.11% Cu、3.07g/t Pd和0.87g/t Pt。矿山主要采用地下开采,采用分段崩落采矿-嗣后充填法开采矿石。年平均开采1650万t硫化矿石。矿山有两个选矿厂,分别处理富矿石、铜矿石和堆存的磁黄铁精矿。富矿石采用优先–混合–分离浮选工艺流程;浸染状矿石采用浮选-重选联合流程,得到镍精矿、铜精矿和磁黄铁矿精矿。矿山有三个冶炼厂,分别处理镍精矿、铜精矿和磁黄铁矿精矿,获得阴极镍、阴极铜、富的铂族金属产品、元素硫、硫酸、银、硒和碲。选矿厂镍精矿镍品位为9.60%,镍回收率为74.0%;铜精矿铜品位为28.5%,镍含量1.18%,铜回收率为73%。     

乳源酪蛋白糖巨肽对溃疡性结肠炎小鼠肠道菌群多样性的影响

研究乳源酪蛋白糖巨肽（casein glycomacropeptide,CGMP）对溃疡性结肠炎（ulcerative colitis,UC）小鼠肠道菌群多样性的影响,从肠道菌群角度探讨乳源CGMP改善溃疡性结肠炎与肠道菌群变化关系的可能机制。恶唑酮（oxazolone,OXZ）诱导小鼠UC模型,设立正常对照组、模型对照组、乳源CGMP组（50 mg/（kg·d））和柳氮磺胺吡啶（salazosulfapyridine,SASP）治疗组（40 mg/（kg·d））,其中正常对照组和模型对照组灌胃相应剂量的生理盐水,连续灌胃7 d。利用Ion Torrent PGM技术检测实验期间小鼠肠道菌群多样性的变化。UC小鼠肠道菌群结构失调,其肠道菌群多样性降低以及优势菌群比例下降。对测序序列通过主成分分析（principal componentanalysis,PCA）、UniFrac等统计分析发现,UC小鼠肠道中厚壁菌门（Firmicutes）和拟杆菌门（Bacteroidetes）的丰度降低而放线菌门（Actinobacteria）和变形菌门（Proteobacteria）的丰度升高。乳源CGMP干预后UC小鼠肠道菌群多样性增加,厚壁菌门和拟杆菌门的相对比例高于模型组,提示乳源CGMP可通过调节失衡的肠道菌群来改善UC。     

Investigating the effect of slag bath conditions on the existence of multiphase emulsion zones in PGM smelting furnaces using computation fluid dynamics

The presence of chrome in electric arc furnaces smelting platinum group metals (PGM’s) has a number of potentially negative consequences. In cases where the slag chrome content is above the saturation limit the existence of near-stagnant conditions near the slag/matte interface increases the risk of chromite spinels settling and consolidating into a “mushy layer”, a three-phase suspension of slag, chromite and matte. The hold-up of matte above the elevation of the slag/matte interface can lead to the attack of freeze linings and copper cooling elements potentially causing failures of the furnace lining and significant downtimes as well as major safety risks. This paper investigates the relationship between typical furnace operating parameters and the behavior of the slag bath with respect to the formation of the “mushy” layer at the slag/matte interface using computational fluid dynamics (CFD). The extent of the potential “mushy” layer is seen to increase with decreasing electrode immersion and furnace power. Electrode immersion is, however, a considerably stronger driver is this regard. The CFD modelling results have aided in selecting appropriate furnace electrode immersion/power combinations intended to minimize “mushy” layer formation.