Improving the performance of concrete using 3D fibres

This paper examines whether 3D fibre reinforcement can improve the toughness and flexural strength of concrete, when compared to equal dosage of straight steel fibres. This work was carried out to determine structural qualities that may lead to potential enhanced performance when concrete is subjected to a bomb blast and in addition the same structural qualities may act as a safety measure in earthquake situations. The majority of injuries caused from bomb attacks are a result of fragmented building components energised by the blast wave, therefore it is vital to reduce fragmentation of concrete. It is known that fibre reinforcement can reduce fragmentation of concrete by increasing energy absorption. A three point beam test was conducted on two batches of beams reinforced with straight steel and 3D fibres respectively, so that flexural strength and post crack toughness could be calculated and compared. A paired comparison test was carried out between the straight steel fibres and the 3D fibres. 3D and straight steel fibres were also embedded in cubes, so that pull out testing could be conducted and compared for the two fibre types. 3D fibre reinforced samples proved to have a higher flexural strength and post crack toughness than straight steel samples. 3D fibres also had a much higher pull out value. After testing, 3D fibres continued to span the rupture plane after initial crack formation during 3 point bend testing, which held together the concrete matrix. These findings suggest 3D fibre reinforced concrete would perform better as a blast protection material when compared to straight steel fibre reinforced concrete, as the results show 3D fibres produce tougher concrete that hold together fragments after loading

The crystal structure of a biological insulated transmembrane molecular wire

A growing number of bacteria are recognized to conduct electrons across their cell envelope, and yet molecular details of the mechanisms supporting this process remain unknown. Here, we report the atomic structure of an outer membrane spanning protein complex, MtrAB, that is representative of a protein family known to transport electrons between the interior and exterior environments of phylogenetically and metabolically diverse microorganisms. The structure is revealed as a naturally insulated biomolecular wire possessing a 10-heme cytochrome, MtrA, insulated from the membrane lipidic environment by embedding within a 26 strand β-barrel formed by MtrB. MtrAB forms an intimate connection with an extracellular 10-heme cytochrome, MtrC, which presents its hemes across a large surface area for electrical contact with extracellular redox partners, including transition metals and electrodes

Successful Implementation of PBIS in an alternative school setting

Mountain Creek Academy is beginning the 6th year of PBIS implementation. Year before last they began to look for ways to make this program meaningful to the population they serve, as many students were placed there for punitive measures. They decided to use the Boys Town model to teach social skills in conjunction with the PBIS framework. This additional curriculum gave the academy the push it needed to move from emergent to operational status on the list of PBIS schools kept by the Georgia Department of Education. Office discipline referrals were reduced by 460%, and the climate of the school was changed. The most significant changes were experienced by the students. They learned necessary social skills and achieved success. Many have been able to generalize those skills to other settings, and many now choose to remain at Mountain Creek Academy due to the feelings of being successful and respected in that environment

Discussing uncertainty and risk in primary care: recommendations of a multi-disciplinary panel regarding communication around prostate cancer screening.

BackgroundShared decision making improves value-concordant decision-making around prostate cancer screening (PrCS). Yet, PrCS discussions remain complex, challenging and often emotional for physicians and average-risk men.ObjectiveIn July 2011, the Centers for Disease Control and Prevention convened a multidisciplinary expert panel to identify priorities for funding agencies and development groups to promote evidence-based, value-concordant decisions between men at average risk for prostate cancer and their physicians.DesignTwo-day multidisciplinary expert panel in Atlanta, Georgia, with structured discussions and formal consensus processes.ParticipantsSixteen panelists represented diverse specialties (primary care, medical oncology, urology), disciplines (sociology, communication, medical education, clinical epidemiology) and market sectors (patient advocacy groups, Federal funding agencies, guideline-development organizations).Main measuresPanelists used guiding interactional and evaluation models to identify and rate strategies that might improve PrCS discussions and decisions for physicians, patients and health systems/society. Efficacy was defined as the likelihood of each strategy to impact outcomes. Effort was defined as the relative amount of effort to develop, implement and sustain the strategy. Each strategy was rated (1-7 scale; 7 = maximum) using group process software (ThinkTank(TM)). For each group, intervention strategies were grouped as financial/regulatory, educational, communication or attitudinal levers. For each strategy, barriers were identified.Key resultsHighly ranked strategies to improve value-concordant shared decision-making (SDM) included: changing outpatient clinic visit reimbursement to reward SDM; development of evidence-based, technology-assisted, point-of-service tools for physicians and patients; reframing confusing prostate cancer screening messages; providing pre-visit decision support interventions; utilizing electronic health records to promote benchmarking/best practices; providing additional training for physicians around value-concordant decision-making; and using re-accreditation to promote training.ConclusionsConference outcomes present an expert consensus of strategies likely to improve value-concordant prostate cancer screening decisions. In addition, the methodology used to obtain agreement provides a model of successful collaboration around this and future controversial cancer screening issues, which may be of interest to funding agencies, educators and policy makers

Characterisation of MtoD from Sideroxydans lithotrophicus: a cytochrome c electron shuttle used in lithoautotrophic growth

The autotrophic Sideroxydans lithotrophicus ES-1 can grow by coupling the oxidation of ferrous iron to the reduction of oxygen. Soluble ferrous iron is oxidised at the surface of the cell by an MtoAB porin-cytochrome complex that functions as an electron conduit through the outer membrane. Electrons are then transported to the cytoplasmic membrane where they are used to generate proton motive force (for ATP synthesis) and NADH for autotrophic processes such as carbon fixation. As part of the mtoAB gene cluster, S. lithotrophicus also contains the gene mtoD that is proposed to encode a cytochrome c protein. We isolated mtoD from a Shewanella oneidensis expression system where the mtoD gene was expressed on a pBAD plasmid vector. Biochemical, biophysical and crystallographic characterisation of the purified MtoD revealed it as an 11 kDa monomeric protein containing a single heme. Sequence and structural alignment indicated that MtoD belonged to the class-1 cytochrome c family and had a similar fold to ferricytochrome c552 family, however the MtoD heme is bis-histidine coordinated and is substantially more exposed than the hemes of other family members. The reduction potential of the MtoD heme at pH 7 was +155 mV vs. Standard Hydrogen Electrode, which is approximately 100 mV lower than that of mitochondrial cytochromes c. Consideration of the properties of MtoD in the context of the potential respiratory partners identified from the genome suggests that MtoD could associate to multiple electron transfer partners as the primary periplasmic electron shuttle

Ostensive signals support learning from novel attention cues during infancy

Social attention cues (e.g., head turning, gaze direction) highlight which events young infants should attend to in a busy environment and, recently, have been shown to shape infants' likelihood of learning about objects and events. Although studies have documented which social cues guide attention and learning during early infancy, few have investigated how infants learn to learn from attention cues. Ostensive signals, such as a face addressing the infant, often precede social attention cues. Therefore, it is possible that infants can use ostensive signals to learn from other novel attention cues. In this training study, 8-month-olds were cued to the location of an event by a novel non-social attention cue (i.e., flashing square) that was preceded by an ostensive signal (i.e., a face addressing the infant). At test, infants predicted the appearance of specific multimodal events cued by the flashing squares, which were previously shown to guide attention to but not inform specific predictions about the multimodal events (Wu and Kirkham, 2010). Importantly, during the generalization phase, the attention cue continued to guide learning of these events in the absence of the ostensive signal. Subsequent experiments showed that learning was less successful when the ostensive signal was absent even if an interesting but non-ostensive social stimulus preceded the same cued events

Resting-State Functional Connectivity in Late-Life Depression: Higher Global Connectivity and More Long Distance Connections

Functional magnetic resonance imaging recordings in the resting-state (RS) from the human brain are characterized by spontaneous low-frequency fluctuations in the blood oxygenation level dependent signal that reveal functional connectivity (FC) via their spatial synchronicity. This RS study applied network analysis to compare FC between late-life depression (LLD) patients and control subjects. Raw cross-correlation matrices (CM) for LLD were characterized by higher FC. We analyzed the small-world (SW) and modular organization of these networks consisting of 110 nodes each as well as the connectivity patterns of individual nodes of the basal ganglia. Topological network measures showed no significant differences between groups. The composition of top hubs was similar between LLD and control subjects, however in the LLD group posterior medial-parietal regions were more highly connected compared to controls. In LLD, a number of brain regions showed connections with more distant neighbors leading to an increase of the average Euclidean distance between connected regions compared to controls. In addition, right caudate nucleus connectivity was more diffuse in LLD. In summary, LLD was associated with overall increased FC strength and changes in the average distance between connected nodes, but did not lead to global changes in SW or modular organization

Mechanisms of Bacterial Extracellular Electron Exchange.

The biochemical mechanisms by which microbes interact with extracellular soluble metal ions and insoluble redox-active minerals have been the focus of intense research over the last three decades. The process presents two challenges to the microorganism; firstly electrons have to be transported at the cell surface, which in Gram negative bacteria presents an additional problem of electron transfer across the ~ 6 nm of the outer membrane. Secondly the electrons must be transferred to or from the terminal electron acceptors or donors. This review covers the known mechanisms that bacteria use to transport electrons across the cell envelope to external electron donors/acceptors. In Gram negative bacteria electron transfer across the outer membrane involves the use of an outer membrane β-barrel and cytochrome. These can be in the form of a porin-cytochrome protein, such as Cyc2 of Acidothiobacillus ferrioxydans, or a multiprotein porin-cytochrome complex like MtrCAB of Shewanella oneidensis MR-1. For mineral respiring organisms there is the additional challenge of transferring the electrons from the cell to mineral surface. For the strict anaerobe Geobacter sulfurreducens this requires electron transfer through conductive pili to associated cytochrome OmcS that directly reduces Fe(III)oxides, while the facultative anaerobe S. oneidensis MR-1 accomplishes mineral reduction through direct membrane contact, contact through filamentous extentions and soluble flavin shuttles, all of which require the outer membrane cytochromes MtrC and OmcA in addition to secreted flavin

The Crystal Structure of the Extracellular 11-heme Cytochrome UndA Reveals a Conserved 10-heme Motif and Defined Binding Site for Soluble Iron Chelates

Members of the genus Shewanella translocate deca- or undeca-heme cytochromes to the external cell surface thus enabling respiration using extracellular minerals and polynuclear Fe(III) chelates. The high resolution structure of the first undeca-heme outer membrane cytochrome, UndA, reveals a crossed heme chain with four potential electron ingress/egress sites arranged within four domains. Sequence and structural alignment of UndA and the deca-heme MtrF reveals the extra heme of UndA is inserted between MtrF hemes 6 and 7. The remaining UndA hemes can be superposed over the heme chain of the decaheme MtrF, suggesting that a ten heme core is conserved between outer membrane cytochromes. The UndA structure has also been crystallographically resolved in complex with substrates, an Fe(III)-nitrilotriacetate dimer or an Fe(III)-citrate trimer. The structural resolution of these UndA-Fe(III)-chelate complexes provides a rationale for previous kinetic measurements on UndA and other outer membrane cytochromes

Role of multiheme cytochromes involved in extracellular anaerobic respiration in bacteria

Heme containing proteins are involved in a broad range of cellular functions, from oxygen sensing and transport to catalyzing oxidoreductive reactions. The two major types of cytochrome (b‐type and c‐type) only differ in their mechanism of heme attachment, but this has major implications for their cellular roles in both localization and mechanism. The b‐type cytochromes are commonly cytoplasmic, or are within the cytoplasmic membrane, while c‐type cytochromes are always found outside of the cytoplasm. The mechanism of heme attachment allows for complex c‐type multiheme complexes, having the capacity to hold multiple electrons, to be assembled. These are increasingly being identified as secreted into the extracellular environment. For organisms that respire using extracellular substrates, these large multiheme cytochromes allow for electron transfer networks from the cytoplasmic membrane to the cell exterior for the reduction of extracellular electron acceptors. In this review the structures and functions of these networks and the mechanisms by which electrons are transferred to extracellular substrates is described