283 research outputs found
Towards the “ultimate earthquake-proof” building: Development of an integrated low-damage system
The 2010–2011 Canterbury earthquake sequence has highlighted the
severe mismatch between societal expectations over the reality of seismic performance
of modern buildings. A paradigm shift in performance-based design criteria
and objectives towards damage-control or low-damage design philosophy and
technologies is urgently required. The increased awareness by the general public,
tenants, building owners, territorial authorities as well as (re)insurers, of the severe
socio-economic impacts of moderate-strong earthquakes in terms of damage/dollars/
downtime, has indeed stimulated and facilitated the wider acceptance and
implementation of cost-efficient damage-control (or low-damage) technologies.
The ‘bar’ has been raised significantly with the request to fast-track the development
of what the wider general public would hope, and somehow expect, to live
in, i.e. an “earthquake-proof” building system, capable of sustaining the shaking of
a severe earthquake basically unscathed.
The paper provides an overview of recent advances through extensive research,
carried out at the University of Canterbury in the past decade towards the development
of a low-damage building system as a whole, within an integrated
performance-based framework, including the skeleton of the superstructure, the
non-structural components and the interaction with the soil/foundation system.
Examples of real on site-applications of such technology in New Zealand, using
concrete, timber (engineered wood), steel or a combination of these materials, and
featuring some of the latest innovative technical solutions developed in the laboratory
are presented as examples of successful transfer of performance-based seismic
design approach and advanced technology from theory to practice
Ontogenetic loops in habitat use highlight the importance of littoral habitats for early life-stages of oceanic fishes in temperate waters
General concepts of larval fish ecology in temperate oceans predominantly associate dispersal and survival to exogenous mechanisms such as passive drift along ocean currents. However, for tropical reef fish larvae and species in inland freshwater systems behavioural aspects of habitat selection are evidently important components of dispersal. This study is focused on larval Atlantic herring (Clupea harengus) distribution in a Baltic Sea retention area, free of lunar tides and directed current regimes, considered as a natural mesocosm. A Lorenz curve originally applied in socio-economics to describe demographic income distribution was adapted to a 20 year time-series of weekly larval herring distribution, revealing size-dependent spatial homogeneity. Additional quantitative sampling of distinct larval development stages across pelagic and littoral areas uncovered a loop in habitat use during larval ontogeny, revealing a key role of shallow littoral waters. With increasing rates of coastal change, our findings emphasize the importance of the littoral zone when considering reproduction of pelagic, ocean-going fish species; highlighting a need for more sensitive management of regional coastal zones
BRB System Out-of-Plane Considerations
This paper describes a simple method for BRB system design considering BRB stability and frame out-ofplane deformation effects. The method seeks to prevent yielding in the BRB system except for in the core
within the BRB restrainer/casing, and it uses standard equations with which engineers are familiar. The method
discourages brace/gusset plate regions which are too flexible, where instability may occur as a result of axial
force, or which are too stiff, where yielding may occur due to out-of-plane frame deformations thereby
compromising the performance in later in-plane deformation cycles. The need to explicitly consider column
twist restraint in the design procedure is emphasized
Energy Considerations for Estimating Displacements of Oscillators with Different Hysteresis Shapes
This paper evaluates the number of cycles of deformation, Nc, of single degree of freedom (SDOF) structures
with different hysteresis loop shapes subjected to earthquake loading because this influences both the peak
displacement and the damage in a structure. The open-source software OpenSEES was modified to allow flagshaped hysteresis loops ranging from elastic bilinear (with no energy dissipation) to traditional bilinear. To
address the current inconsistency in the literature the concept of oscillation resistance ratio (ORR) has been
introduced before. A relationship to estimate (ORR) for oscillators with different displacement ductility and a
flag-shaped hysteresis loop is developed under free vibration, assuming no damping and no strain hardening.
This relationship, initially developed using simple mechanics considerations, is then compared with that found
from a time history analysis. The relationship is then extended to consider the effects of tangent stiffness
proportional damping. The number of oscillation cycles, Nc, is defined as the number of post-initial elastic
displacement excursions obtained during shaking to the number in one full cycle to the same peak
displacement. Relationships between Nc and ORR were developed for structures with lateral force reduction
factor, R, period, T, and damping assuming no strain hardening using a suite of 9 earthquakes records.
It was found that estimated ORR for the mechanics-based method and time history analysis considering free
vibration were identical for all flag shape loop shapes. For a damping ratio of 5%, the ORR obtained increased
by less than 12% compared to 0% damping for the flag-shaped parameters greater than 0.2. As a result, the ORR for a loop with no damping was used in the remainder of the paper. In general, as the ORR decreased to
less than 0.3 (i.e. the hysteresis loop had less energy dissipation), Nc increased. It was found that Nc was
insensitive to the lateral force reduction factor, but increased for lower damping when ORR was less than 0.3.
Also, it increased for shorter period oscillators when ORR was less than 0.3, but the trends were less clear with
greater ORR
Effects of near-fault ground motions on the nonlinear behaviour of reinforced concrete framed buildings
Ocular medicines in children: the regulatory situation related to clinical research
<p>Abstract</p> <p>Background</p> <p>Many ocular medications are prescribed for paediatric patients, but the evidence for their rational use is very scant. This study was planned to compare the availability and the licensing status of ocular medications marketed in Italy, the United Kingdom (UK), and the United States of America (USA) related to the amount of published and un-published RCTs testing these drugs in the paediatric population.</p> <p>Methods</p> <p>A quantitative analysis was performed to evaluate the number of ocular medications with a paediatric license in Italy, the UK, and the USA. A literature search was also performed in MEDLINE, EMBASE, and The Cochrane Central Register of Controlled Trials for randomized controlled trials (RCTs) on ophthalmic pharmacological therapy in children aged < 18 years, published up to December 2010. A search in the international clinical trial registries, the list of paediatric investigation plans (PIPs) approved by European Medicines Agency (EMA), and the table of medicines with new paediatric information approved by Food and Drug Administration (FDA) was also performed.</p> <p>Results</p> <p>In all, of 197 drugs identified, 68 (35%) single drugs are licensed for paediatric use at least in one considered country, while 23 (12%) were marketed in all three countries. More specifically, in Italy 43 single drugs (48% of those marketed) had a paediatric license, while 39 (64%) did in the UK and 22 (54%) did in the USA. Only 13 drugs were marketed with a paediatric license in all countries.</p> <p>The percentage of drugs licensed for paediatric use and for which at least one RCT had been performed ranged between 51% in Italy and 55% in the USA. No published RCTs were found for 11 (48%) drugs licensed for paediatric use in all three countries. In all, 74 (35%) of the retrieved RCTs involved mydriatic/cycloplegic medications.</p> <p>A total of 62 RCTs (56% completed) on 46 drugs were found in the international clinical trial registries. Cyclosporin and bevacizumab were being studied in many ongoing trials. Twenty-six drugs had new paediatric information approved by FDA based on new paediatric clinical trials, while only 4 PIPs were approved by EMA.</p> <p>Conclusions</p> <p>There is a pressing need for further research and clinical development in the pediatric ophthalmic area, where effective up-to-date treatments, and additional research and education on use in children, remain priorities.</p
A Novel Cre Recombinase Imaging System for Tracking Lymphotropic Virus Infection In Vivo
BACKGROUND:Detection, isolation, and identification of individual virus infected cells during long term infection are critical to advance our understanding of mechanisms of pathogenesis for latent/persistent viruses. However, current approaches to study these viruses in vivo have been hampered by low sensitivity and effects of cell-type on expression of viral encoded reporter genes. We have designed a novel Cre recombinase (Cre)-based murine system to overcome these problems, and thereby enable tracking and isolation of individual in vivo infected cells. METHODOLOGY/PRINCIPAL FINDINGS:Murine gammaherpesvirus 68 (MHV-68) was used as a prototypic persistent model virus. A Cre expressing recombinant virus was constructed and characterised. The virus is attenuated both in lytic virus replication, producing ten-fold lower lung virus titres than wild type virus, and in the establishment of latency. However, despite this limitation, when the sEGFP7 mouse line containing a Cre-activated enhanced green fluorescent protein (EGFP) was infected with the Cre expressing virus, sites of latent and persistent virus infection could be identified within B cells and macrophages of the lymphoid system on the basis of EGFP expression. Importantly, the use of the sEGFP7 mouse line which expresses high levels of EGFP allowed individual virus positive cells to be purified by FACSorting. Virus gene expression could be detected in these cells. Low numbers of EGFP positive cells could also be detected in the bone marrow. CONCLUSIONS/SIGNIFICANCE:The use of this novel Cre-based virus/mouse system allowed identification of individual latently infected cells in vivo and may be useful for the study and long-term monitoring of other latent/persistent virus infections
Social Expectations Bias Decision-Making in Uncertain Inter-Personal Situations
Understanding the role that social cues have on interpersonal choice, and their susceptibility to contextual effects, is of core importance to models of social decision-making. Language, on the other hand, is one of the main means of communication during social interactions in our culture. The present experiments tested whether positive and negative linguistic descriptions of alleged partners in a modified Ultimatum Game biased decisions made to the same set of offers, and whether the contextual uncertainty of the game modulated this biasing effect. The results showed that in an uncertain context, the same offers were accepted with higher probability when they were preceded by positive rather than by negative valenced trait-words. Participants also accepted fair offers with higher probability than unfair offers, but this effect did not interact with the valence of the social descriptive words. In addition, the speed of the decision was affected by valence: acceptance choices were faster when they followed a positive adjective, whereas rejection responses were faster after a negative-valenced word. However, these effects were highly reduced when the uncertainty was eliminated from the game. This suggests that positive and negative relevant social information can bias decisions made to the same pieces of evidence during interpersonal interactions, but that this mainly takes place when the uncertainty associated with the choices is high
Proof of impact and pipeline planning: directions and challenges for social audit in the health sector
Social audits are typically observational studies, combining qualitative and quantitative uptake of evidence with consultative interpretation of results. This often falters on issues of causality because their cross-sectional design limits interpretation of time relations and separation out of other indirect associations
Electrocardiographic Left Ventricular Hypertrophy and Outcome in Hemodialysis Patients
BACKGROUND AND AIMS: Electrocardiography (ECG) is the most widely used initial screening test for the assessment of left ventricular hypertrophy (LVH), an independent predictor of cardiovascular mortality in patients with end-stage renal disease (ESRD). However, traditional ECG criteria based only on voltage to detect LVH have limited clinical utility for the detection of LVH because of their poor sensitivity. METHODS: This prospective observational study was undertaken to compare the prognostic significance of commonly used ECG criteria for LVH, namely Sokolow-Lyon voltage (SV) or voltage-duration product (SP) and Cornell voltage (CV) or voltage-duration product (CP) criteria, and to investigate the association between echocardiographic LV mass index (LVMI) and ECG-LVH criteria in ESRD patients, who consecutively started maintenance hemodialysis (HD) between January 2006 and December 2008. RESULTS: A total of 317 patients, who underwent both ECG and echocardiography, were included. Compared to SV and CV criteria, SP and CP criteria, respectively, correlated more closely with LVMI. In addition, CP criteria provided the highest positive predictive value for echocardiographic LVH. The 5-year cardiovascular survival rates were significantly lower in patients with ECG-LVH by each criterion. In multivariate analyses, echocardiographic LVH [adjusted hazard ratio (HR): 11.71; 95% confidence interval (CI): 1.57-87.18; P = 0.016] and ECG-LVH by SP (HR: 3.43; 95% CI: 1.32-8.92; P = 0.011) and CP (HR: 3.07; 95% CI: 1.16-8.11; P = 0.024) criteria, but not SV and CV criteria, were significantly associated with cardiovascular mortality. CONCLUSIONS: The product of QRS voltage and duration is helpful in identifying the presence of LVH and predicting cardiovascular mortality in incident HD patients
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