The Role of Shrinkage Strains Causing Early-Age Cracking in Cast-in-Place Concrete Bridge Decks

Early-age cracking in cast-in-place reinforced concrete bridge decks is occurring more frequently now than three decades ago and principle factors that lead to early-age deck cracking are not fully understood. A finite element (FE) simulation methodology for assessing the role of shrinkage-induced strains in generating early-age bridge deck cracking is described. The simulations conducted indicate that drying shrinkage appears to be capable of causing transverse (and possibly longitudinal) bridge deck cracks as early as 9 to II days after bridge deck placement. The drying-shrinkage induced stresses would result in transverse cracking over interior pier supports in a typical bridge superstructure considered in the finite element simulations conducted

Fatigue Risks in the Connections of Sign Support Structures

This research effort develops a reliability-based approach for prescribing inspection intervals for mast-arm sign support structures corresponding to user-specified levels of fatigue-induced fracture risk. The resulting level of risk for a particular structure is dependent upon its geographical location, the type of connection it contains, the orientation of its mast-arm relative to north and the number of years it has been in service. The results of this research effort indicate that implementation of state-of-the-art reliability-based assessment procedures can contribute very valuable procedures for assigning inspection protocols (i.e. inspection intervals) that are based upon probabilities of finding fatigue-induced cracking in these structures. The engineering community can use the results of this research effort to design inspection intervals based upon risk and thereby better align inspection needs with limited fiscal and human resources

Efficient data representation for XML in peer-based systems

Purpose - New directions in the provision of end-user computing experiences mean that the best way to share data between small mobile computing devices needs to be determined. Partitioning large structures so that they can be shared efficiently provides a basis for data-intensive applications on such platforms. The partitioned structure can be compressed using dictionary-based approaches and then directly queried without firstly decompressing the whole structure. Design/methodology/approach - The paper describes an architecture for partitioning XML into structural and dictionary elements and the subsequent manipulation of the dictionary elements to make the best use of available space. Findings - The results indicate that considerable savings are available by removing duplicate dictionaries. The paper also identifies the most effective strategy for defining dictionary scope. Research limitations/implications - This evaluation is based on a range of benchmark XML structures and the approach to minimising dictionary size shows benefit in the majority of these. Where structures are small and regular, the benefits of efficient dictionary representation are lost. The authors' future research now focuses on heuristics for further partitioning of structural elements. Practical implications - Mobile applications that need access to large data collections will benefit from the findings of this research. Traditional client/server architectures are not suited to dealing with high volume demands from a multitude of small mobile devices. Peer data sharing provides a more scalable solution and the experiments that the paper describes demonstrate the most effective way of sharing data in this context. Social implications - Many services are available via smartphone devices but users are wary of exploiting the full potential because of the need to conserve battery power. The approach mitigates this challenge and consequently expands the potential for users to benefit from mobile information systems. This will have impact in areas such as advertising, entertainment and education but will depend on the acceptability of file sharing being extended from the desktop to the mobile environment. Originality/value - The original work characterises the most effective way of sharing large data sets between small mobile devices. This will save battery power on devices such as smartphones, thus providing benefits to users of such devices

Protein microenvironments for topology analysis

Previously held under moratorium from 1st December 2016 until 1st December 2021Amino Acid Residues are often the focus of research on protein structures. However, in a folded protein, each residue finds itself in an environment that is defined by the properties of its surrounding residues. The term microenvironment is used herein to refer to these local ensembles. Not only do they have chemical properties but also topological properties which quantify concepts such as density, boundaries between domains and junction complexity. These quantifications are used to project a protein’s backbone structure into a series of scores. The hypothesis was that these sequences of scores can be used to discover protein domains and motifs and that they can be used to align and compare groups of 3D protein structures. This research sought to implement a system that could efficiently compute microenvironments such that they can be applied routinely to large datasets. The computation of the microenvironments was the most challenging aspect in terms of performance, and the optimisations required are described. Methods of scoring microenvironments were developed to enable the extraction of domain and motif data without 3D alignment. The problem of allosteric site detection was addressed with a classifier that gave high rates of allosteric site detection. Overall, this work describes the development of a system that scales well with increasing dataset sizes. It builds on existing techniques, in order to automatically detect the boundaries of domains and demonstrates the ability to process large datasets by application to allosteric site detection, a problem that has not previously been adequately solved.Amino Acid Residues are often the focus of research on protein structures. However, in a folded protein, each residue finds itself in an environment that is defined by the properties of its surrounding residues. The term microenvironment is used herein to refer to these local ensembles. Not only do they have chemical properties but also topological properties which quantify concepts such as density, boundaries between domains and junction complexity. These quantifications are used to project a protein’s backbone structure into a series of scores. The hypothesis was that these sequences of scores can be used to discover protein domains and motifs and that they can be used to align and compare groups of 3D protein structures. This research sought to implement a system that could efficiently compute microenvironments such that they can be applied routinely to large datasets. The computation of the microenvironments was the most challenging aspect in terms of performance, and the optimisations required are described. Methods of scoring microenvironments were developed to enable the extraction of domain and motif data without 3D alignment. The problem of allosteric site detection was addressed with a classifier that gave high rates of allosteric site detection. Overall, this work describes the development of a system that scales well with increasing dataset sizes. It builds on existing techniques, in order to automatically detect the boundaries of domains and demonstrates the ability to process large datasets by application to allosteric site detection, a problem that has not previously been adequately solved

Introduction of d-Glutamate at a Critical Residue of Aβ42 Stabilizes a Prefibrillary Aggregate with Enhanced Toxicity.

The amyloid beta peptide 42 (Aβ42) is an aggregation-prone peptide that plays a pivotal role in Alzheimer's disease. We report that a subtle perturbation to the peptide through a single chirality change at glutamate 22 leads to a pronounced delay in the β-sheet adoption of the peptide. This was accompanied by an attenuated propensity of the peptide to form fibrils, which was correlated with changes at the level of the fibrillary architecture. Strikingly, the incorporation of d-glutamate was found to stabilize a soluble, ordered macromolecular assembly with enhanced cytotoxicity to PC12 cells, highlighting the importance of advanced prefibrillary Aβ aggregates in neurotoxicity

Sharing large data collections between mobile peers

New directions in the provision of end-user computing experiences mean that we need to determine the best way to share data between small mobile computing devices. Partitioning large structures so that they can be shared efficiently provides a basis for data-intensive applications on such platforms. In conjunction with such an approach, dictionary-based compression techniques provide additional benefits and help to prolong battery life

Gatekeeping vs. Balancing in the Constitutional Law of Elections: Methodological Uncertainty on the High Court

This Essay examines the methodological upheaval created by the quartet of constitutional election law cases decided during October Term 2007. Prior to this Term, the ascendant analytic approach called for a threshold characterization of the burden on the plaintiff\u27s rights, which characterization determined whether the court would apply strict scrutiny or lax, rational-basis-like review. The characterization was generally formal in nature. But in light of the Supreme Court\u27s latest decisions, it is now open to a lower court adjudicating a First Amendment or Equal Protection challenge to an election law-absent a Supreme Court precedent squarely on point- (1) to engage in unmediated, all-things-considered balancing, focusing either on the overall reasonableness of the challenged law or on the reasonableness of exempting or otherwise accommodating the plaintiff or plaintiff-class; (2) to apply strict scrutiny after determining that the law (relative to some practicable alternative) has a large, demonstrable adverse impact on voting, political association, or the competitiveness of campaigns; (3) to apply strict scrutiny after identifying a facial attribute of the law itself that renders it suspect in the judge\u27s eye; (4) to apply extremely deferential review because the law does not have attributes that the judge deems facially suspect and because the judge is leery of getting bogged down in empirical debates or indulging in the guess work of open-ended balancing; or (5) to reject the claim after positing that it raises questions about democratic fairness concerning which there is no discernable historical consensus. During October Term 2007, the Court vacillated among these approaches, while providing precious little guidance to lower courts about the circumstances that warrant one or another methodology. We suggest that the methodological pluralism in these decisions, coupled with a lack of explicit normative direction, may indicate that most Justices are approaching constitutional election law thinking less about doctrinal coherence or interpretive principle than about the instrumental consequences of their rulings for the system of government as a whole

The Impact of Parental Marital Disruption on Children's Performance in School

Although it is well-documented that children from divorced or single-parent families have lower performance in school, little is known about whether the timing of divorce is linked to a decline in school performance. In this paper, we examine whether and how the timing of change in parents' marital status influences the odds that a child is held back a grade in school using the Baltimore Parenthood Study, a thirty-year longitudinal study that has tracked the lives of inner-city families. Using logistic regression and hazard analysis, we show that the odds that a child is held back in school increase dramatically around the period of marital dissolution