6,172 research outputs found
Advances in Evaluating Tsunami Forces on Coastal Structures
At source, tsunami waves have relatively small wave heights (typically 0.5-2m), but very
long wavelengths. As these waves approaches the shoreline and enter the shallower waters, their
wavelength reduces and their wave height increases dramatically. The resulting waves can cause
violent impacts on infrastructure and structures, and the long wavelengths lead to extensive
inundation inland causing destruction over large areas of coast as seen recently in Japan (2011).
Clearly there is a need for a systematic analysis of the physics of tsunami flows in and around
buildings and the forces and pressures they produce on structures as a function of time. The first steps
towards such a study are presented. This paper presents preliminary observations obtained from sets
of unique physical experiments designed to study the impact of tsunami-like waves on coastal
structures towards the development of tsunami design/assessment guidance
Advances in Evaluating Tsunami Forces on Coastal Structures
At source, tsunami waves have relatively small wave heights (typically 0.5-2m), but very
long wavelengths. As these waves approaches the shoreline and enter the shallower waters, their
wavelength reduces and their wave height increases dramatically. The resulting waves can cause
violent impacts on infrastructure and structures, and the long wavelengths lead to extensive
inundation inland causing destruction over large areas of coast as seen recently in Japan (2011).
Clearly there is a need for a systematic analysis of the physics of tsunami flows in and around
buildings and the forces and pressures they produce on structures as a function of time. The first steps
towards such a study are presented. This paper presents preliminary observations obtained from sets
of unique physical experiments designed to study the impact of tsunami-like waves on coastal
structures towards the development of tsunami design/assessment guidance
Synchronised neural signature of creative mental imagery in reality and augmented reality
Creativity, transforming imaginative thinking into reality, is a mental imagery simulation in essence. It can be incorporeal, concerns sophisticated and/or substantial thinking, and involves objects. In the present study, a mental imagery task consisting of creating a scene using familiar (FA) or abstract (AB) physical or virtual objects in real (RMI) and augmented reality (VMI) environments, and an execution task involving effectively creating a scene in augmented reality (VE), were utilised. The beta and gamma neural oscillations of healthy participants were recorded via a 32 channel wireless 10/20 international EGG system. In real and augmented environments and for both the mental imagery and execution tasks, the participants displayed a similar cortico-cortical neural signature essentially based on synchronous vs asynchronous beta and gamma oscillatory activities between anterior (i.e. frontal) and posterior (i.e. parietal, occipito-parietal and occipito-temporal) areas bilaterally. The findings revealed a transient synchronised neural architecture that appears to be consistent with the hypothesis according to which, creativity, because of its inherent complexity, cannot be confined to a single brain area but engages various interconnected networks
Minor troponin T elevation and mortality in patients with atrial fibrillation presenting to the emergency department
Background There are limited data on the association of minor troponin elevation in unselected patients with atrial fibrillation (AF) presenting to the emergency department (ED) with adverse events. In this study, we sought to assess the early and mid-term mortality of these patients. Methods In this observational study, 2911 patients with AF were admitted to the ED. They were divided into 3 groups based on peak high-sensitivity troponin (TnT) levels: normal ( Results All-cause mortality was 6.7% (n = 196) at 30 days and 22.2% (n = 646) at 1 year. Mortality rate increased along with increasing levels of TnT irrespective of baseline covariates, primary discharge diagnosis and type of AF. A significant association between TnT levels and all-cause mortality was observed. The adjusted hazard ratio (HR) at 30 days was 6.02 (95% CI 2.62-13.83) for TnT 15-50 ng/L and 11.28 (95% CI 4.87-26.12) for TnT 51-100 ng/L (P Conclusions Among patients with AF admitted to the ED, increased TnT levels were associated with increased early and mid-term all-cause mortality irrespective of baseline covariates and type of AF.Peer reviewe
Anterior Z250 resin composite restorations: one-year evaluation of clinical performance.
AbstractThe purpose of this
practice-based study was to compare the clinical performance of a new
universal composite resin material (Z250) used for Class III and V
cavities in anterior teeth. Restorative materials (Z250 and Z100; 3 M
ESPE) placed by six operators were used for a total of 150 restorations
during the 6-month enrollment period. After 1 year, 141 restorations (76
Z250 and 66 Z100) were available and evaluated for overall quality,
color match, marginal adaptation, surface appearance and the presence of
secondary caries, using modified USPHS criteria. The overall quality
was excellent for both materials and no significant changes were noted
during the follow-up. None of the scores between the two materials were
statistically significant. Major changes were seen in color match and
surface appearance. At baseline, the color match of 71% of Z250 and 62%
of Z100 was rated as Alfa, after 1 year the figures were 60 and 65%.
Regarding surface appearance, 97% of the Z250 were rated Alfa at
baseline, whereas at 1 year the figure was 76%. For Z100, the scores
were 94 and 79%, respectively. After 1 year, the clinical performance of
Z250 restorative composite resin was clinically acceptable and similar
to that of Z100.</div
The Effects of Twitter Sentiment on Stock Price Returns
Social media are increasingly reflecting and influencing behavior of other
complex systems. In this paper we investigate the relations between a well-know
micro-blogging platform Twitter and financial markets. In particular, we
consider, in a period of 15 months, the Twitter volume and sentiment about the
30 stock companies that form the Dow Jones Industrial Average (DJIA) index. We
find a relatively low Pearson correlation and Granger causality between the
corresponding time series over the entire time period. However, we find a
significant dependence between the Twitter sentiment and abnormal returns
during the peaks of Twitter volume. This is valid not only for the expected
Twitter volume peaks (e.g., quarterly announcements), but also for peaks
corresponding to less obvious events. We formalize the procedure by adapting
the well-known "event study" from economics and finance to the analysis of
Twitter data. The procedure allows to automatically identify events as Twitter
volume peaks, to compute the prevailing sentiment (positive or negative)
expressed in tweets at these peaks, and finally to apply the "event study"
methodology to relate them to stock returns. We show that sentiment polarity of
Twitter peaks implies the direction of cumulative abnormal returns. The amount
of cumulative abnormal returns is relatively low (about 1-2%), but the
dependence is statistically significant for several days after the events
Non-extremal Localised Branes and Vacuum Solutions in M-Theory
Non-extremal overlapping p-brane supergravity solutions localised in their
relative transverse coordinates are constructed. The construction uses an
algebraic method of solving the bosonic equations of motion. It is shown that
these non-extremal solutions can be obtained from the extremal solutions by
means of the superposition of two deformation functions defined by vacuum
solutions of M-theory. Vacuum solutions of M-theory including irrational powers
of harmonic functions are discussed.Comment: LaTeX, 16 pages, no figures, typos correcte
Antimony-doped graphene nanoplatelets
Heteroatom doping into the graphitic frameworks have been intensively studied for the development of metal-free electrocatalysts. However, the choice of heteroatoms is limited to non-metallic elements and heteroatom-doped graphitic materials do not satisfy commercial demands in terms of cost and stability. Here we realize doping semimetal antimony (Sb) at the edges of graphene nanoplatelets (GnPs) via a simple mechanochemical reaction between pristine graphite and solid Sb. The covalent bonding of the metalloid Sb with the graphitic carbon is visualized using atomic-resolution transmission electron microscopy. The Sb-doped GnPs display zero loss of electrocatalytic activity for oxygen reduction reaction even after 100,000 cycles. Density functional theory calculations indicate that the multiple oxidation states (Sb3+ and Sb5+) of Sb are responsible for the unusual electrochemical stability. Sb-doped GnPs may provide new insights and practical methods for designing stable carbon-based electrocatalystsclose0
Stress and Strain in Flat Piling of Disks
We have created a flat piling of disks in a numerical experiment using the
Distinct Element Method (DEM) by depositing them under gravity. In the
resulting pile, we then measured increments in stress and strain that were
associated with a small decrease in gravity. We first describe the stress in
terms of the strain using isotropic elasticity theory. Then, from a
micro-mechanical view point, we calculate the relation between the stress and
strain using the mean strain assumption. We compare the predicted values of
Young's modulus and Poisson's ratio with those that were measured in the
numerical experiment.Comment: 9 pages, 1 table, 8 figures, and 2 pages for captions of figure
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