Energy-Aware Decentralised Medium Access Control for Wireless Sensor Networks

The success of future Internet-of-Things (IoT) based application deployments depends on the ability of wireless sensor platforms to sustain uninterrupted operation based on: (i) environmental energy harvesting and optimised coupling with the platform’s energy consumption when processing and transmitting/receiving data; (ii) spontaneous adaptation to changes in the local network topology without requiring central coordination. To address the first aspect, starting from practical deployments of a multi-transducer platform for photovoltaic and piezoelectric energy harvesting and the associated modelling and analysis, data-driven probability models are derived to facilitate the optimal coupling of energy production and consumption when processing and transmitting data. To address the second aspect (adaptability), the new concept of decentralised time-synchronised channel swapping (DT-SCS) is proposed – a novel protocol for the medium access control (MAC) layer of IEEE 802.15.4-based wireless sensor networks (WSNs). Simulation results reveal that DT-SCS comprises an excellent candidate for completely decentralised MAC layer coordination in WSNs by providing quick convergence to steady state, high bandwidth utilisation, high connectivity, robustness to interference and low energy consumption. Moreover, performance results via a Contiki-OS based deployment on TelosB motes reveal that DT-SCS comprises an excellent candidate for a decentralised multichannel MAC layer

Introduction: locating gentrification in the Global East

This special issue, a collection of papers presented and debated at an Urban Studies Foundation-funded workshop on Global Gentrification in London in 2012, attempts to problematise contemporary understandings of gentrification, which is all too often confined to the experiences of the so-called Global North, and sometimes too narrowly understood as classic gentrification. Instead of simply confirming the rise of gentrification in places outside of the usual suspects of North America and Western Europe, a more open-minded approach is advocated so as not to over-generalise distinctive urban processes under the label of gentrification, thus understanding gentrification as constitutive of diverse urban processes at work. This requires a careful attention to the complexity of property rights and tenure relations, and calls for a dialogue between gentrification and non-gentrification researchers to understand how gentrification communicates with other theories to capture the full dynamics of urban transformation. Papers in this special issue have made great strides towards these goals, namely theorising, distorting, mutating and bringing into question the concept of gentrification itself, as seen from the perspective of the Global East, a label that we have deliberately given in order to problematise the existing common practices of grouping all regions other than Western European and North American ones into the Global South

Comparative analysis of carboxysome shell proteins

Carboxysomes are metabolic modules for CO2 fixation that are found in all cyanobacteria and some chemoautotrophic bacteria. They comprise a semi-permeable proteinaceous shell that encapsulates ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO) and carbonic anhydrase. Structural studies are revealing the integral role of the shell protein paralogs to carboxysome form and function. The shell proteins are composed of two domain classes: those with the bacterial microcompartment (BMC; Pfam00936) domain, which oligomerize to form (pseudo)hexamers, and those with the CcmL/EutN (Pfam03319) domain which form pentamers in carboxysomes. These two shell protein types are proposed to be the basis for the carboxysome’s icosahedral geometry. The shell proteins are also thought to allow the flux of metabolites across the shell through the presence of the small pore formed by their hexameric/pentameric symmetry axes. In this review, we describe bioinformatic and structural analyses that highlight the important primary, tertiary, and quaternary structural features of these conserved shell subunits. In the future, further understanding of these molecular building blocks may provide the basis for enhancing CO2 fixation in other organisms or creating novel biological nanostructures

The place and barriers of evidence based practice: knowledge and perceptions of medical, nursing and allied health practitioners in malaysia

<p>Abstract</p> <p>Background</p> <p>Despite a recent increase in activities to promote evidence-based practice (EBP), it was unclear how Malaysian hospital practitioners received this new approach in medicine. This study examines their confidence and perceptions on EBP.</p> <p>Findings</p> <p>We conducted cross-sectional surveys using a self-administered questionnaire during two EBP training courses in two Malaysian hospitals in January and June 2007. Our subjects (n = 144) were doctors and nursing and allied health staff (NAH) participating in the EBP courses. Our questionnaire covered three domains: confidence and understanding (six items), attitude (five items) and barriers to practice (four items). We presented simple descriptive statistics, including the sum ratings and the proportions with different responses for each item, and compared different groups using Mann-Whitney U test for scaled ratings and Chi-square test for dichotomous responses.</p> <p>Ninety-two doctors and 52 NAH staff completed the surveys. Overall, doctors expressed slightly higher confidence on EBP compared to NAH staff. Out of a maximum sum rating of 27 over six items, doctors reported an average of 18.3 (SD 3.2) and NAH staff reported an average of 16.0 (SD 3.4), p = 0.002. Doctors were also more positive in their views on EBP. For example, 67.4% of doctors disagreed, but 61% of NAH staff agreed that "the importance of EBP in patient care is exaggerated", and 79.3% of doctors disagreed, but 46.2% of NAH staff agreed that "EBP is too tedious and impractical". Similar responses were observed for other items in the domain.</p> <p>Doctors and NAH staff shared similar concerns on barriers to evidence-based practice. The highest proportions considered poor facilities to access evidence a barrier (76% of doctors and 90% of NAH), followed by poor awareness of evidence (62% of doctors and 70% of NAH) and time constraints (63% of doctors and 68% of NAH), p = 0.09 for the combined rating of four items in the domain.</p> <p>Conclusions</p> <p>The findings of our survey suggest a need for greater efforts in promoting EBP among Malaysian hospital practitioners especially for NAH staff. From the responses based on the barriers to EBP, improving facilities for accessing evidence and promoting more user-friendly resources to address time constraints appear to be the priorities.</p

Drive counts as a method of estimating ungulate density in forests: mission impossible?

Although drive counts are frequently used to estimate the size of deer populations in forests, little is known about how counting methods or the density and social organization of the deer species concerned influence the accuracy of the estimates obtained, and hence their suitability for informing management decisions. As these issues cannot readily be examined for real populations, we conducted a series of ‘virtual experiments’ in a computer simulation model to evaluate the effects of block size, proportion of forest counted, deer density, social aggregation and spatial auto-correlation on the accuracy of drive counts. Simulated populations of red and roe deer were generated on the basis of drive count data obtained from Polish commercial forests. For both deer species, count accuracy increased with increasing density, and decreased as the degree of aggregation, either demographic or spatial, within the population increased. However, the effect of density on accuracy was substantially greater than the effect of aggregation. Although improvements in accuracy could be made by reducing the size of counting blocks for low-density, aggregated populations, these were limited. Increasing the proportion of the forest counted led to greater improvements in accuracy, but the gains were limited compared with the increase in effort required. If it is necessary to estimate the deer population with a high degree of accuracy (e.g. within 10% of the true value), drive counts are likely to be inadequate whatever the deer density. However, if a lower level of accuracy (within 20% or more) is acceptable, our study suggests that at higher deer densities (more than ca. five to seven deer/100 ha) drive counts can provide reliable information on population size

Alkalizing Reactions Streamline Cellular Metabolism in Acidogenic Microorganisms

An understanding of the integrated relationships among the principal cellular functions that govern the bioenergetic reactions of an organism is necessary to determine how cells remain viable and optimise their fitness in the environment. Urease is a complex enzyme that catalyzes the hydrolysis of urea to ammonia and carbonic acid. While the induction of urease activity by several microorganisms has been predominantly considered a stress-response that is initiated to generate a nitrogen source in response to a low environmental pH, here we demonstrate a new role of urease in the optimisation of cellular bioenergetics. We show that urea hydrolysis increases the catabolic efficiency of Streptococcus thermophilus, a lactic acid bacterium that is widely used in the industrial manufacture of dairy products. By modulating the intracellular pH and thereby increasing the activity of β-galactosidase, glycolytic enzymes and lactate dehydrogenase, urease increases the overall change in enthalpy generated by the bioenergetic reactions. A cooperative altruistic behaviour of urease-positive microorganisms on the urease-negative microorganisms within the same environment was also observed. The physiological role of a single enzymatic activity demonstrates a novel and unexpected view of the non-transcriptional regulatory mechanisms that govern the bioenergetics of a bacterial cell, highlighting a new role for cytosol-alkalizing biochemical pathways in acidogenic microorganisms

Measurement of the cross-section of high transverse momentum vector bosons reconstructed as single jets and studies of jet substructure in pp collisions at √s = 7 TeV with the ATLAS detector

This paper presents a measurement of the cross-section for high transverse momentum W and Z bosons produced in pp collisions and decaying to all-hadronic final states. The data used in the analysis were recorded by the ATLAS detector at the CERN Large Hadron Collider at a centre-of-mass energy of √s = 7 TeV;{\rm Te}{\rm V}$and correspond to an integrated luminosity of$4.6\;{\rm f}{{{\rm b}}^{-1}}$. The measurement is performed by reconstructing the boosted W or Z bosons in single jets. The reconstructed jet mass is used to identify the W and Z bosons, and a jet substructure method based on energy cluster information in the jet centre-of-mass frame is used to suppress the large multi-jet background. The cross-section for events with a hadronically decaying W or Z boson, with transverse momentum${{p}_{{\rm T}}}\gt 320\;{\rm Ge}{\rm V}$and pseudorapidity$|\eta |\lt 1.9$, is measured to be${{\sigma }_{W+Z}}=8.5\pm 1.7$ pb and is compared to next-to-leading-order calculations. The selected events are further used to study jet grooming techniques

Search for pair-produced long-lived neutral particles decaying to jets in the ATLAS hadronic calorimeter in ppcollisions at √s=8TeV

The ATLAS detector at the Large Hadron Collider at CERN is used to search for the decay of a scalar boson to a pair of long-lived particles, neutral under the Standard Model gauge group, in 20.3fb−1of data collected in proton–proton collisions at √s=8TeV. This search is sensitive to long-lived particles that decay to Standard Model particles producing jets at the outer edge of the ATLAS electromagnetic calorimeter or inside the hadronic calorimeter. No significant excess of events is observed. Limits are reported on the product of the scalar boson production cross section times branching ratio into long-lived neutral particles as a function of the proper lifetime of the particles. Limits are reported for boson masses from 100 GeVto 900 GeV, and a long-lived neutral particle mass from 10 GeVto 150 GeV

Search for direct pair production of the top squark in all-hadronic final states in proton-proton collisions at s√=8 TeV with the ATLAS detector

The results of a search for direct pair production of the scalar partner to the top quark using an integrated luminosity of 20.1fb−1 of proton–proton collision data at √s = 8 TeV recorded with the ATLAS detector at the LHC are reported. The top squark is assumed to decay via t˜→tχ˜01 or t˜→ bχ˜±1 →bW(∗)χ˜01 , where χ˜01 (χ˜±1 ) denotes the lightest neutralino (chargino) in supersymmetric models. The search targets a fully-hadronic final state in events with four or more jets and large missing transverse momentum. No significant excess over the Standard Model background prediction is observed, and exclusion limits are reported in terms of the top squark and neutralino masses and as a function of the branching fraction of t˜ → tχ˜01 . For a branching fraction of 100%, top squark masses in the range 270–645 GeV are excluded for χ˜01 masses below 30 GeV. For a branching fraction of 50% to either t˜ → tχ˜01 or t˜ → bχ˜±1 , and assuming the χ˜±1 mass to be twice the χ˜01 mass, top squark masses in the range 250–550 GeV are excluded for χ˜01 masses below 60 GeV