HotMobile 2008: Postconference Report

HotMobile 2008 presented a two-day program on mobile computing systems and applications. The authors focuses on the sessions on sensors, modularity, wireless, security, systems, and screens. The mobile device is the most amazing invention in history and that it has had the largest impact on human kind. Because mobile phones combine mobile devices with ongoing developments in software and communication technologies, they have the potential to change the way people think and act

Serogroup Conversion of Vibrio cholerae in Aquatic Reservoirs

The environmental reservoirs for Vibrio cholerae are natural aquatic habitats, where it colonizes the chitinous exoskeletons of copepod molts. Growth of V. cholerae on a chitin surface induces competence for natural transformation, a mechanism for intra-species gene exchange. The antigenically diverse O-serogroup determinants of V. cholerae are encoded by a genetically variable biosynthetic cluster of genes that is flanked on either side by chromosomal regions that are conserved between different serogroups. To determine whether this genomic motif and chitin-induced natural transformation might enable the exchange of serogroup-specific gene clusters between different O serogroups of V. cholerae, a strain of V. cholerae O1 El Tor was co-cultured with a strain of V. cholerae O139 Bengal within a biofilm on the same chitin surface immersed in seawater, and O1-to-O139 transformants were obtained. Serogroup conversion of the O1 recipient by the O139 donor was demonstrated by comparative genomic hybridization, biochemical and serological characterization of the O-antigenic determinant, and resistance of O1-to-O139 transformants to bacteriolysis by a virulent O1-specific phage. Serogroup conversion was shown to have occurred as a single-step exchange of large fragments of DNA. Crossovers were localized to regions of homology common to other V. cholerae serogroups that flank serogroup-specific encoding sequences. This result and the successful serogroup conversion of an O1 strain by O37 genomic DNA indicate that chitin-induced natural transformation might be a common mechanism for serogroup conversion in aquatic habitats and for the emergence of V. cholerae variants that are better adapted for survival in environmental niches or more pathogenic for humans

Inhibiting antimicrobial resistance in Staphylococcus aureus using natural products

Since the treatment of infections with antibiotics, Staphylococcus aureus has developed resistance to antimicrobial agents. Methicillin-resistant S aureus (MRSA) contributes significantly to the healthcare burden of both hospital and community infections. Investigation into the resistance mechanism and their inhibition has the potential to increase the effectiveness in treating infection. It is hypothesized that the diversity of compounds and efficacy found in complex natural product extracts would lead to active leads that inhibit bacterial resistance. Using synergistic activity testing as a guide to a fractionation process, 3 flavonoids (8-desmethyl-sideroxylin, sideroxylin, and 6-desmethyl-sideroxlyn) were identified as synergists within a Hydrastis canadensis extract. These compounds were further characterized as efflux pump inhibitors using fluorescence in real-time and under confocal microscopy. In addition to disrupting efflux, the ability of S. aureus to cause disease was investigated. By detecting auto-inducing peptide I (AIP I), a direct product in the activation of this pathway, inhibition via natural products could be determined. Disruption in the intercellular communication via the Agr quorum sensing pathway in MRSA was observed in a Penicillium fungus and in H. canadensis. This quorum sensing inhibition (quorum quenching) limits virulence and toxin production making it easier for the host to manage infection

Meaningful Metrics for Evaluating Eventual Consistency

Abstract. Optimistic replication is a fundamental technique for supporting collaborative work practices in mobile environments. However, eventual consistency, in contrast to immediate strong consistency in pessimistic replication, is much harder to evaluate. This paper analyzes different metrics for measuring the effectiveness of eventually consistent systems. Using results from a simulated environment of relevant optimistic replication protocols, we show that each metric hides previously undocumented side effects. These add considerable imprecision to any evaluation that exclusively relies on a single metric. Hence, we advocate a combined methodology comprising three complementary metrics: commit ratio, average agreement delay and average commit delay.

Biosocial Worlds

Biosocial Worlds presents state-of-the-art contributions to anthropological reflections on the porous boundaries between human and non-human life – biosocial worlds. Based on changing understandings of biology and the social, it explores what it means to be human in these worlds. Growing separation of scientific disciplines for more than a century has maintained a separation of the ‘natural’ and the ‘social’ that has created a space for projections between the two. Such projections carry a directional causality and so constitute powerful means to establish discursive authority. While arguing against the separation of the biological and the social in the study of human and non-human life, it remains important to unfold the consequences of their discursive separation. Based on examples from Botswana, Denmark, Mexico, the Netherlands, Uganda, the UK and USA, the volume explores what has been created in the space between ‘the social’ and ‘the natural’, with a view to rethink ‘the biosocial’. Health topics in the book include diabetes, trauma, cancer, HIV, tuberculosis, prevention of neonatal disease and wider issues of epigenetics. Many of the chapters engage with constructions of health and disease in a wide range of environments, and engage with analysis of the concept of ‘environment’. Anthropological reflection and ethnographic case studies explore how ‘health’ and ‘environment’ are entangled in ways that move their relation beyond interdependence to one of inseparability. The subtitle of this volume captures these insights through the concept of ‘health environment’, seeking to move the engagement of anthropology and biology beyond deterministic projections. ; Biosocial Worlds brings together state-of-the-art contributions to critical anthropological reflection on, and ethnographic exploration of, human and non-human life in the light of our changing understandings of biology and what it means to be human

Biosocial Worlds: Anthropology of health environments beyond determinism

Biosocial Worlds presents state-of-the-art contributions to anthropological reflections on the porous boundaries between human and non-human life – biosocial worlds. Based on changing understandings of biology and the social, it explores what it means to be human in these worlds. Growing separation of scientific disciplines for more than a century has maintained a separation of the ‘natural’ and the ‘social’ that has created a space for projections between the two. Such projections carry a directional causality and so constitute powerful means to establish discursive authority. While arguing against the separation of the biological and the social in the study of human and non-human life, it remains important to unfold the consequences of their discursive separation. Based on examples from Botswana, Denmark, Mexico, the Netherlands, Uganda, the UK and USA, the volume explores what has been created in the space between ‘the social’ and ‘the natural’, with a view to rethink ‘the biosocial’. Health topics in the book include diabetes, trauma, cancer, HIV, tuberculosis, prevention of neonatal disease and wider issues of epigenetics. Many of the chapters engage with constructions of health and disease in a wide range of environments, and engage with analysis of the concept of ‘environment’. Anthropological reflection and ethnographic case studies explore how ‘health’ and ‘environment’ are entangled in ways that move their relation beyond interdependence to one of inseparability. The subtitle of this volume captures these insights through the concept of ‘health environment’, seeking to move the engagement of anthropology and biology beyond deterministic projections

Mechanisms of tigecycline resistance in the Enterobacteriaceae and <i>Acinetobacter baumannii</i>

Tigecycline is the first glycylcycline to enter clinical use and displays good in vitro activity against a broad range of Gram-positive and Gram-negative pathogens. It is often used as an agent of last resort for the treatment of infections caused by multidrug-resistant Gram-negative bacteria including some Enterobacteriaceae species and Acinetobacter baumannii. Therefore, the recent emergence of tigecycline resistance in some strains of these species is a serious public health concern. Efflux was investigated as a possible mechanism of tigecycline resistance using pre- and post-therapy pairs of clinical isolates and laboratory-selected, tigecycline-resistant mutants of A. baumannii and Enterobacter cloacae and a type strain, laboratory mutants, and a clinical isolate of Serratia marcescens. Minimum inhibitory concentrations (MICs) of tigecycline and other agents were determined by agar dilution. Pulsed-field gel electrophoresis was used to assign clones / determine isolate relatedness. Expression of efflux pump genes and genes thought to be implicated in their regulation was monitored by real-time reverse-transcriptase polymerase chain reaction and their role in tigecycline resistance was further investigated by knockout mutagenesis. There was an association between increased expression of specific resistance-nodulation-division (RND) efflux pump genes and elevated tigecycline MICs in all species studied. Insertional inactivation of RND efflux pump genes implicated the AdeABC, AcrAB and SdeXY-HasF systems of A. baumannii, E. cloacae and S. marcescens, respectively. The results of this study support the hypothesis that tigecycline resistance in clinical isolates of Gram-negative bacteria arises as a result of the up-regulated activity of intrinsic efflux systems of the RND family