As técnicas e algoritmos desenvolvidos sobre diferentes infraestruturas específicas dificilmente podem ser comparados entre si. Este princípio também se aplica às infraestruturas para execução de Memória Transacional Distribuída (MTD), pois não só são muito escassas aquelas que permitem o desenvolvimento, teste e comparação de vários algoritmos e técnicas de implementação, como fornecem uma interface intrusiva para o programador. Sem uma comparação justa, não é possível aferir quais as técnicas e algoritmos mais apropriados em cada contexto de utilização (workload). Neste artigo propomos uma infraestrutura generalista, muito flexível, que possibilita a experimentação de várias estratégias de MTD, permitindo o desenvolvimento de uma grande variedade de algoritmos e de técnicas de implementação eficientes e otimizadas. Através da sua utilização, é agora possível a comparação de técnicas e algoritmos em diferentes contextos de utilização (workloads), recorrendo a uma única infraestrutura e com implicações mínimas no código da aplicação.

Affinity chromatography with protein A from Staphylococcus aureus (SpA) is the most widespread and
accepted methodology for antibody capture during the downstream process of antibody manufacturing.
A triazine based ligand (ligand 22/8) was previously developed as an inexpensive and robust alternative
to SpA chromatography (Li et al. [12] and Teng et al. [11]). Despite the experimental success, there is no
structural information on the binding modes of ligand 22/8 to antibodies, namely to Immunoglobulin G
(IgG) molecules and fragments. In this work, we addressed this issue by a molecular docking approach
allied to molecular dynamics simulations. Theoretical results confirmed the preference of the synthetic
ligand to bind IgG through the binding site found in the crystallographic structure of the natural complex
between SpA and the Fc fragment of IgG. Our studies also suggested other unknown “hot-spots” for
specific binding of the affinity ligand at the hinge between VH and CH1 domains of Fab fragment. The best
docking poses were further analysed by molecular dynamics studies at three different protonation states
(pH 3, 7 and 11). The main interactions between ligand 22/8 and the IgG fragments found at pH 7 were
weaker at pH 3 and pH 11 and in these conditions the ligand start losing tight contact with the binding
site, corroborating the experimental evidence for protein elution from the chromatographic adsorbents
at these pH conditions.

Consider a set of methods implementing an Application Programming Interface (API) of a given library or program module that is to be used in a multithreaded setting. If those methods were not originally designed to be thread safe, races and deadlocks are expected to happen. This work introduces the novel concept of program closure and describes how it can be applied in a methodology used to make the library or module implementation thread safe, by identifying the high level data races introduced by interleaving the parallel execution of methods from the API. High-level data races result from the misspecification of the scope of an atomic block, by wrongly splitting it into two or more atomic blocks sharing a data dependency. Roughly speaking, the closure of a program P, clos(P), is obtained by incrementally adding new threads to P in such a way that enables the identification of the potential high level data races that may result from running P in parallel with other programs. Our model considers the methods implementing the API of a library of program module as concurrent programs and computes and analyses their closure in order to identify high level data races. These high level data races are inspected and removed to make the interface thread safe. We illustrate the application of this methodology with a simple use case.

This paper presents an automatic verification technique for transactional memory Java programs executing under snapshot isolation level. We certify which transactions in a program are safe to execute under snapshot isolation without triggering the write-skew anomaly, opening the way to run-time optimizations that may lead to considerable performance enhancements. Our work builds on a novel deep-heap analysis technique based on separation logic to statically approximate the read- and write-sets of a transactional memory Java program. We implement our technique and apply our tool to a set of micro benchmarks and also to one benchmark of the STAMP package. We corroborate known results, certifying some of the examples for safe execution under snapshot isolation by proving the absence of write-skew anomalies. In other cases our analysis has identified transactions that potentially trigger previously unknown write-skew anomalies.

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Typical Distributed Transactional Memory (DTM) systems provide serializability by detecting read-write conflicts between accesses to shared data objects. Detecting read-write conflicts requires the bookkeeping of all the read and write accesses to the shared objects made inside the transaction, and the validation of all these accesses in the end of a transaction. For most DTM algorithms, the validation of a transaction requires the broadcast of its read-set to all the nodes of the distributed system during the commit phase. Since applications tend to read more than write, the overhead associated with the bookkeeping of read accesses, and the amount of network traffic generated during the commit, is a main performance problem in DTM systems. Database systems frequently rely on weaker isolation models to improve performance. In particular, Snapshot Isolation (SI) is widely used in industry. An interesting aspect of SI is that only write-write conflicts are checked at commit time and considered for detecting conflicting transactions. As main result, a DTM using this isolation model does not need to keep track of the read accesses, considerably reducing the bookkeeping overhead, and also eliminates the need of broadcasting the read-set at transaction commit time, thus reducing the network traffic and considerably increase the scalability of the whole system. By only detecting write-write conflicts, this isolation model allows a much higher commit rate, which comes at the expense of allowing some real conflicting transactions to commit. Thus, relaxing the isolation of a transactional program may lead previously correct programs to misbehave due to the anomalies resulting from malign data-races that are now allowed by the relaxed transactional run-time. These anomalies can be precisely characterized, and are often called in the literature as write-skew anomalies. Write-skew anomalies can be avoided dynamically with the introduction of algorithms that verify the serializability of running transactions, which may result in a non-negligible overhead. Our approach is to avoid the run-time overhead by statically asserting that a DTM program will execute without generating write-skew anomalies at runtime, while only verifying write-write conflicts. Conflicting transactions can be made “safe” by code rewriting using well known techniques. Our verification technique uses separation logic, a logic for verifying intensive heap manipulation programs, which was extended to construct abstract read- and write-sets for each transaction in the DTM program. This verification technique is implemented in the StarTM tool, which analyzes transactional Java bytecode programs. The transactions that cannot be verified by our tool are executed under serializable isolation (detecting read-write conflicts), while for the “safe” transactions we only detect write-write conflicts. The results of our experiments when verifying micro-benchmarks, such as linked lists and binary trees, and partially verifying some macro-benchmarks, such as the STAMP benchmark, strongly encourage the ongoing work for the application of this technique to DTM.

The scientific controversy generated around the destiny given to the fraction of hazardous industrial waste produced in Portugal and how the country dealt with this situation was the stand out point in Souselas case. Here, the dominant aspect of the analysis focused on the implementation of a solution for the treatment of hazardous industrial waste. These wastes result from industrial processes contain or are contaminated, by substances that, at certain concentrations, represent a risk to human health or to the environment. Their treatment can be done using co-incineration in existing cement factories. Having in mind the environment analysis of a controversial process, through the statements made by the different actors involved, the case of Souselas was our object of study. Initially, the actors involved in the process were identified and characterized, in terms of position, interests and / or concerns. This analysis has strengthened with the gathering of documentary elements of analysis. In a second phase the historical process was prepared. Only then, the conditions to make an interpretation of what really happened in the process were gathered, then , it was possible to identify which parts were successful and unsuccessful, and to interpret “why” these successes and failures occurred. Thus, after the identification of key variables and leverage points, a causal diagram and a schematic simulation of the behaviour of reference in case Souselas was designed. We conclude that the process of Souselas was a significant milestone with regard to social organization and spontaneous local actors in situations of opposition to central government decisions with local impact. It was also a turning point in governance according to the model of representative democracy, whose technocratic and elitist character is called into question. The Souselas case emphasized itself as a microcosm on the conflict of interests that we find at a global level heightened since the 90s and that

Since its invention, paper has become one of the main carriers of our cultural, scientific, political, economic and historical information. Given the importance of this material, its preservation is a matter of great interest. Paper can be deteriorated due to physical, chemical and biological agents. Within microorganisms, fungi are the major paper biodeteriogens. Throughout history, several methods have been used to prevent and stop fungal deterioration on paper based materials. In this work we present a review of the main chemical and physical methods used to avoid fungal paper biodeterioration until nowadays and also of some new approaches tested recently. The advantages and disadvantages of these methods are discussed as well as their health effects. Studies regarding antifungal compositions, methods of application, performance and effects on the treated materials are also presented with the aim of providing a clear set of conclusions on the topic. (C) 2012 Elsevier Ltd. All rights reserved.

A gene encoding Bfr (bacterioferritin) was identified and isolated from the genome of Desulfovibrio vulgaris cells, and overexpressed in Escherichia coli. In vitro, H2O2 oxidizes Fe2+ ions at much higher reaction rates than O-2. The H2O2 oxidation of two Fe2+ ions was proven by Mossbauer spectroscopy of rapid freeze-quenched samples. On the basis of the Mossbauer parameters of the intermediate species we propose that D. vulgaris Bfr follows a mineralization mechanism similar to the one reported for vertebrate H-type ferritins subunits, in which a diferrous centre at the ferroxidase site is oxidized to diferric intermediate species, that are subsequently translocated into the inner nanocavity. D. vulgaris recombinant Bfr oxidizes and stores up to 600 iron atoms per protein. This Bfr is able to bind DNA and protect it against hydroxyl radical and DNase deleterious effects. The use of H2O2 as an oxidant, combined with the DNA binding and protection activities, seems to indicate a DPS (DNA-binding protein from starved cells)-like role for D. vulgaris Bfr.

A strategy for the development of novel antimicrobials is to combine the stability and pleiotropic effects of inorganic compounds with the specificity and efficiency of organic compounds, such as antibiotics. Here we report on the use of gold:silver-alloy (Au:Ag-alloy) nanoparticles, obtained via a single-step citrate co-reduction method, combined to conventional antibiotics to enhance their antimicrobial effect on bacteria. Addition of the alloy nanoparticles considerably decreased the dose of antibiotic necessary to show antimicrobial effect, both for bacterial cells growing in rich medium in suspension and for bacterial cells resting in a physiological buffer on a humid cellulose surface. The observed effect was more pronounced than the sum of the individual effects of the nanoparticles and antibiotic. We demonstrate the enhancement effect of Au:Ag-alloy nanoparticles with a size distribution of 32.5±7.5nm mean diameter on the antimicrobial effect of (i) kanamycin onEscherichia coli(Gram-negative bacterium), and (ii) a β-lactam antibiotic on both a sensitive and resistant strain ofStaphylococcus aureus(Gram-positive bacterium). Together, these results may pave the way for the combined use of nanoparticle–antibiotic conjugates towards decreasing antibiotic resistance currently observed for certain bacteria and conventional antibiotics.