Usage control in computer security: A survey

Protecting access to digital resources is one of the fundamental problems recognized in computer security. As yet it remains a challenging problem to work out, starting from the design of a system until its implementation. Access control is defined as the ability to permit or deny access to a particular resource (object) by a particular entity (subject). Three most widely used traditional access control models are: Discretionary Access Control (DAC), Mandatory Access Control (MAC), and Role Based Access Control (RBAC).Traditional access control solutions do not respond adequately to new challenges addressed by modern computer systems. Today highly distributed, network-connected, heterogeneous and open computing environment requires a fine-grained, flexible, persistent and continuous model for protecting the access and usage of digital resources.This paper surveys the literature on Usage Control (UCON) model proposed by Park and Sandhu (2002) [1], Park (2003) [2] and Zhang (2006) [3]. Usage control is a novel and promising approach for access control in open, distributed, heterogeneous and network-connected computer environments. It encompasses and enhances traditional access control models, Trust Management (TM) and Digital Rights Management (DRM), and its main novelties are mutability of attributes and continuity of access decision evaluation.     

Fire Retardance in Poly(butylene terephthalate). The Effects of Red Phosphorus and Radiation‐Induced Cross‐Links

Summary: The combustion performance of poly(butylene terephthalate) (PBT) can be improved by the addition of red phosphorus provided it is intermolecularly cross‐linked upon irradiation with ⁶⁰Co γ‐rays in the presence of triallyl cyanurate (TAC). At a content of 3 or 4 wt.‐% the latter significantly promotes cross‐linking in the presence of air. From combustion tests with samples containing red phosphorus (P_red) and having been γ‐irradiated in the presence of TAC it turned out that an improved fire resistance of PBT is achieved if the red phosphorus content is at least 12.5 wt.‐%. In this case test samples were self‐extinguishing and the UL 94 rating corresponded to V‐1. Product analysis and thermal gravimetric analysis revealed that P_red stimulates aromatization and charring. These processes involve the reaction of P_red with the polymer. ³¹P NMR spectroscopy revealed that the residue contained chemically bonded phosphorus.

Decomposition of anhydride groups resulting in phenyl radicals.     

Open Questions on Reliable Measurements of Soret Coefficients

This study was motivated by experimental problems arising in the design of optical digital interferometry for measurements of Soret coefficients in laboratory conditions. Our attention is mainly focused on thermal design of the set-up. The goal is to establish a linear temperature profile inside the experimental cell while heating from above. The measures for preventing deleterious convection inside the working liquid and outside the experimental cell (in the surrounding gas) are carefully examined. It is pointed out that both convection in the liquid and in the surrounding gas have a strong negative effect on the quality of optical measurements.     

Synthesis and long-term stability of acrylic acid and N,N-methylene-bis-acrylamide radiation grafted polypropylene fibers

New carboxyl ion-exchange fibers prepared by acrylic acid (AA) and N, N-methylene-bis-acrylamide (MBAA) monomer grafting to polypropylene (PP) fibers based on the method of γ-rays pre-irradiation in air followed by a Mohr's salt redox initiation of grafting reaction were studied. Grafting degree, homopolymer quantity, monomer conversion and grafting efficiency were determined. FTIR spectroscopy was used to establish the nature of the grafted fibers. The thermal stability of the materials was investigated based on DSC analysis in N₂/O₂ mixture. The long-term stability during 6–8 years of storage was examined by the measurement of the tensile strength and the elongation at break of the fibers, and the chemical oxygen demand in water extracts as well as in the oxygen uptake experiments. The influence of some factors on the useful life of the grafted fibers was studied: a MBAA cross-linking, exposure to day light, the Fe (III) residue presence, a grafting reaction temperature. It was found that small amounts of the adsorbed Fe (III) ions increase the deterioration rate of the grafted fibers, while small amounts of MBAA delay this negative process.     

Computing minimal mappings between lightweight ontologies

As a valid solution to the semantic heterogeneity problem, many matching solutions have been proposed. Given two lightweight ontologies, we compute the minimal mapping, namely the subset of all possible correspondences, that we call mapping elements, between them such that (i) all the others can be computed from them in time linear in the size of the input ontologies and (ii) none of them can be dropped without losing property (i). We provide a formal definition of minimal mappings and define a time efficient computation algorithm which minimizes the number of comparisons between the nodes of the two input ontologies. The experimental results show a substantial improvement both in the computation time and in the number of mapping elements which need to be handled, for instance for validation, navigation, and search.     

白鬼笔蘑菇菌丝体多糖:免疫调节和伤口愈合特性

白鬼笔蘑菇在亚洲和北欧是一种传统的民间医药。本文综述了我们人工培养白鬼笔菌丝体的研究成果,以及从白鬼笔菌丝体中分离出的多糖的生物活性数据。对白鬼笔新菌株菌丝体的培养形态特征和生理生化特性进行了研究。经过优化培养基的营养物构成和培养条件能够使菌体生物量提高1.3倍,多糖含量提高1.5~1.7倍。从该菌丝体中分离的多糖在体外和在体内（链脲佐菌素诱导的糖尿病大鼠）均具有免疫调节作用。与原始软膏相比,含有10%白鬼笔多糖的软膏,能促进实验大鼠的皮肤创面愈合,促进肉芽组织的上皮形成、收缩和生长。综上所述,白鬼笔菌丝体多糖有望成为开发功能性食品以及新型治疗和预防药物的原材料。     

白鬼笔蘑菇菌丝体多糖：免疫调节和伤口愈合特性（英文）

白鬼笔蘑菇在亚洲和北欧是一种传统的民间医药。本文综述了我们人工培养白鬼笔菌丝体的研究成果,以及从白鬼笔菌丝体中分离出的多糖的生物活性数据。对白鬼笔新菌株菌丝体的培养形态特征和生理生化特性进行了研究。经过优化培养基的营养物构成和培养条件能够使菌体生物量提高1.3倍,多糖含量提高1.5～1.7倍。从该菌丝体中分离的多糖在体外和在体内(链脲佐菌素诱导的糖尿病大鼠)均具有免疫调节作用。与原始软膏相比,含有10%白鬼笔多糖的软膏,能促进实验大鼠的皮肤创面愈合,促进肉芽组织的上皮形成、收缩和生长。综上所述,白鬼笔菌丝体多糖有望成为开发功能性食品以及新型治疗和预防药物的原材料。     

Radiation-induced decomposition of anion exchange resins

Radiation-induced degradation of the strongly basic anion exchange resin Amberlite™ IRA400 in , Cl⁻ and OH⁻ forms has been studied. The research focused on the formation of molecular hydrogen in the gamma-radiolysis of water slurries of these quaternary ammonium resins with varying water content. Extended studies with various electron scavengers (, N₂O and O₂) prove an important role of in the formation of H₂ from these resins. An excess production of H₂ in these systems at about 85% water weight fraction was found to be due to trimethylamine, dimethylamine and other compounds that leach from the resin to the aqueous phase. Irradiations with 5 MeV ⁴He ions were performed to simulate the effects of α-particles.     

High-Density Plasmonic Nanopores for DNA Sensing at Ultra-Low Concentrations by Plasmon-Enhanced Raman Spectroscopy

Solid-state nanopores are implemented in new and promising platforms that are capable of sensing fundamental biomolecular constituents at the single-molecule level. However, several limitations and drawbacks remain. For example, the current strategies based on both electrical and optical sensing suffer from low analyte capture rates and challenging nanofabrication procedures. In addition, their limited discrimination power hinders their application in the detection of complex molecular constructs. In contrast, Raman spectroscopy has recently demonstrated the ability to discriminate both nucleotides and amino acids. Herein, a plasmonic nanoassembly is proposed supporting nanopores at high density, in the order of 100 pores per µm². These findings demonstrate that the device has a high capture rate in the range of a few fm . The pore size is ≈10 nm in diameter and provides an amplification of the electromagnetic field exceeding 10³ in intensity at 785 nm. Owing to these features, single-molecule detection is achieved by means of surface-enhanced Raman scattering from a solution containing 50 fm DNA molecules (≈4.4 kilobase pairs). Notably, the reported spectra show an average number of 2.5 Raman counts per nucleotide. From this perspective, this number is not far from what is necessary to discriminate the DNA sequence.