High-yield neutral sulfite pulps

Information reviewed and reaffirmed 1962. Original report issued March 1956

Hypervirulent Clostridium difficile PCR-Ribotypes Exhibit Resistance to Widely Used Disinfectants

The increased prevalence of Clostridium difficile infection (CDI) has coincided with enhanced transmissibility and severity of disease, which is often linked to two distinct clonal lineages designated PCR-ribotype 027 and 017 responsible for CDI outbreaks in the USA, Europe and Asia. We assessed sporulation and susceptibility of three PCR-ribotypes; 012, 017 and 027 to four classes of disinfectants; chlorine releasing agents (CRAs), peroxygens, quaternary ammonium compounds (QAC) and biguanides. The 017 PCR-ribotype, showed the highest sporulation frequency under these test conditions. The oxidizing biocides and CRAs were the most efficacious in decontamination of C. difficile vegetative cells and spores, the efficacy of the CRAs were concentration dependent irrespective of PCR-ribotype. However, there were differences observed in the susceptibility of the PCR-ribotypes, independent of the concentrations tested for Virkon®, Newgenn®, Proceine 40® and Hibiscrub®. Whereas, for Steri7® and Biocleanse® the difference observed between the disinfectants were dependent on both PCR-ribotype and concentration. The oxidizing agent Perasafe® was consistently efficacious across all three PCR ribotypes at varying concentrations; with a consistent five Log10 reduction in spore titre. The PCR-ribotype and concentration dependent differences in the efficacy of the disinfectants in this study indicate that disinfectant choice is a factor for llimiting the survival and transmission of C. difficile spores in healthcare settings

Short- and Long-Term Biomarkers for Bacterial Robustness: A Framework for Quantifying Correlations between Cellular Indicators and Adaptive Behavior

The ability of microorganisms to adapt to changing environments challenges the prediction of their history-dependent behavior. Cellular biomarkers that are quantitatively correlated to stress adaptive behavior will facilitate our ability to predict the impact of these adaptive traits. Here, we present a framework for identifying cellular biomarkers for mild stress induced enhanced microbial robustness towards lethal stresses. Several candidate-biomarkers were selected by comparing the genome-wide transcriptome profiles of our model-organism Bacillus cereus upon exposure to four mild stress conditions (mild heat, acid, salt and oxidative stress). These candidate-biomarkers—a transcriptional regulator (activating general stress responses), enzymes (removing reactive oxygen species), and chaperones and proteases (maintaining protein quality)—were quantitatively determined at transcript, protein and/or activity level upon exposure to mild heat, acid, salt and oxidative stress for various time intervals. Both unstressed and mild stress treated cells were also exposed to lethal stress conditions (severe heat, acid and oxidative stress) to quantify the robustness advantage provided by mild stress pretreatment. To evaluate whether the candidate-biomarkers could predict the robustness enhancement towards lethal stress elicited by mild stress pretreatment, the biomarker responses upon mild stress treatment were correlated to mild stress induced robustness towards lethal stress. Both short- and long-term biomarkers could be identified of which their induction levels were correlated to mild stress induced enhanced robustness towards lethal heat, acid and/or oxidative stress, respectively, and are therefore predictive cellular indicators for mild stress induced enhanced robustness. The identified biomarkers are among the most consistently induced cellular components in stress responses and ubiquitous in biology, supporting extrapolation to other microorganisms than B. cereus. Our quantitative, systematic approach provides a framework to search for these biomarkers and to evaluate their predictive quality in order to select promising biomarkers that can serve to early detect and predict adaptive traits

Checking the Expressivity of Firewall Languages

Designing and maintaining firewall configurations is hard, also for expert system administrators. Indeed, policies are made of a large number of rules and are written in low-level configuration languages that are specific to the firewall system in use. As part of a larger group, we have addressed these issues and have proposed a semantic-based transcompilation pipeline. It is supported by FWS, a tool that analyses a real configuration and ports it from a firewall system to another. To our surprise, we discovered that some configurations expressed in a real firewall system cannot be ported to another system, preserving the semantics. Here we outline the main reasons for the detected differences between the firewall languages, and describe F2F, a tool that checks if a given configuration in a system can be ported to another system, and reports its user on which parts cause problems and why

Are All Firewall Systems Equally Powerful?

Firewalls are a fundamental tool for managing and protecting computer networks. They not only permit specifying which packets are allowed to enter a network, but also how these packets are modified by translating IP addresses and performing port redirection (NAT). Many firewalls systems are available which provide different tools and configuration languages. In contrast with the intuition, the most widespread languages cannot express the same configurations, even when simple filtering and NAT transformations are considered. This paper formally investigates the power of firewall languages of the most used tools in Unix and Linux. In particular, we introduce two kinds of expressivity. The first concerns the ways a packet can be transformed by NAT. According to this criterion iptables is strictly more expressive than ipfw and pf that are equivalent. The second kind is more finer-grained and considers the dependencies among the management of all packets. Our results show that some configurations are expressible in a system, but not in another one. Indeed, iptables is incomparable with the others, and ipfw is more expressive than pf