2,993 research outputs found
Seismic vulnerability of churches in Faial and Pico islands, Azores
Earthquakes represent one of the main cause of serious damage and loss of historic and architectural heritage. Interventions to preserve these building should start with a careful knowledge and assessment of their seismic vulnerability, in order to support any needed retrofitting and strengthening measures.
This paper proposes a procedure to register and diagnose of the level of damage on churches after the occurrence of an earthquake, and also to assess the seismic vulnerability of this type of construction. This procedure was applied to sixteen churches in the Azores islands which were hit by the July 9th 1998 earthquake.
Belfries of church towers are elements with a particular seismic vulnerability. For this reason, and based on the Italian methodology proposed by the Linee Guida (2006), it is applied to belfries of two churches from Pico (Azores), a simplified mechanical model for assessment of seismic vulnerability of this type of structures
Are Stroke Occurrence and Outcome Related to Weather Parameters? Results from a Population-Based Study in Northern Portugal
Background: Changes in meteorological parameters have
been associated with cardiovascular mortality and stroke.
The high incidence of stroke in Portugal may be modelled by
short- or long-term weather changes whose effect may be
different across stroke types and severity. Methods: Data include
all patients with a first-ever-in-a-lifetime stroke registered
in a population of 86,023 residents in the city of Porto
from October 1998 to September 2000. Specific stroke types
were considered and ischaemic stroke (IS) subtype was defined
according to the Oxfordshire Community Stroke Projet
classification and the Trial of Org 10172 in Acute Stroke Treatment
(TOAST) criteria. Information on daily temperature, humidity
and air pressure was obtained from the National Meteorological
Office. The Poisson distribution was used to
model the daily number of events as a function of each
weather parameter measured over different hazard periods,
and the binomial model to contrast effects across subgroups.
Differential effects of meteorological parameters
and hazard periods upon stroke occurrence and outcome
were analysed in a stepwise model. Results: Among the 462 patients registered, 19.6% had a primary intracerebral haemorrhage
(PICH) and 75.3% an IS. Among patients with IS,
21.6% were total anterior circulation infarcts (TACIs), 19.8%
partial anterior circulation infarcts (PACIs), 19.5% posterior
circulation infarcts (POCIs) and 39.1% were lacunar infarcts
(LACIs). The aetiology of IS was large artery atherosclerosis in
6.9%, cardioembolism in 23.3% and small artery occlusion in
35.6%. The incidence of PICH increased by 11.8% (95% CI:
3.8–20.4%) for each degree drop in the diurnal temperature
range in the preceding day. The incidence of IS increased by
3.9% (95% CI: 1.6–6.3%) and cardioembolic IS by 5.0% (95%
CI: 0.2–10.1%) for a 1 ° C drop in minimum temperature in the
same hazard period. The incidence of TACIs followed the IS
pattern while for PACIs and POCIs there were stronger effects
of longer hazard periods and no association was found
for LACIs. The relative risk of a fatal versus a non-fatal stroke
increased by 15.5% (95% CI: 6.1–25.4%) for a 1 ° C drop in maximum
temperature over the previous day. Conclusions: Outdoor
temperature and related meteorological parameters
are associated with stroke occurrence and severity. The different
hazard periods for temperature effects and the absence
of association with LACIs may explain the heterogeneous
effects of weather on stroke occurrence found in community-
based and hospital admission studies. Emergency
services should be aware that specific weather conditions
are more likely to prompt calls for more severe strokes
The isotopic composition (d15N, d13C) of agricultural wastes and derived composts.
The aim of this study was to measure variations in the isotopic composition (d13C and d15N) during the composting of different agricultural wastes using bench-scale bioreactors. Four different feedstocks of agricultural wastes (Horse bedding manure + legumes residues; Dairy manure + Jatropha mill cake; Dairy manure + sugarcane residues; Dairy manure) were used for aerobic-thermophilic composting. During composting no significant differences were found between the d13C values of the source material and the compost, except for Dairy manure + sugarcane residues. d15N values increased significantly in composts of Horse bedding manure + legumes residues and Dairy manure + Jatropha mill cake. d15N values of composts may be related to NH3 volatilization during the composting process. Isotopic signatures (d13C, d15N) can be used to differentiate composts from different feedstock sources and d15N values may be a quantitative indicator of NH3 volatilization during composting. Use of bench-scale bioreactors is a promising apparatus to study the dynamics of C and N and stable isotopes signatures during composting, but future adjustments regarding sampling methodology are necessary
An Ultra-Stable Referenced Interrogation System in the Deep Ultraviolet for a Mercury Optical Lattice Clock
We have developed an ultra-stable source in the deep ultraviolet, suitable to
fulfill the interrogation requirements of a future fully-operational lattice
clock based on neutral mercury. At the core of the system is a Fabry-P\'erot
cavity which is highly impervious to temperature and vibrational perturbations.
The mirror substrate is made of fused silica in order to exploit the
comparatively low thermal noise limits associated with this material. By
stabilizing the frequency of a 1062.6 nm Yb-doped fiber laser to the cavity,
and including an additional link to LNE-SYRTE's fountain primary frequency
standards via an optical frequency comb, we produce a signal which is both
stable at the 1E-15 level in fractional terms and referenced to primary
frequency standards. The signal is subsequently amplified and frequency-doubled
twice to produce several milliwatts of interrogation signal at 265.6 nm in the
deep ultraviolet.Comment: 7 pages, 6 figure
Functionalizing self-assembled GaN quantum dot superlattices by Eu-implantation
Self-assembled GaN quantum dots (QDs) stacked in superlattices (SL) with AlN spacer layers were implanted with Europium ions to fluences of 1013, 1014, and 1015 cm−2. The damage level introduced in the QDs by the implantation stays well below that of thick GaN epilayers. For the lowest fluence, the structural properties remain unchanged after implantation and annealing while for higher fluences the implantation damage causes an expansion of the SL in the [0001] direction which increases with implantation fluence and is only partly reversed after thermal annealing at 1000 °C. Nevertheless, in all cases, the SL quality remains very good after implantation and annealing with Eu ions incorporated preferentially into near-substitutional cation sites. Eu3+ optical activation is achieved after annealing in all samples. In the sample implanted with the lowest fluence, the Eu3+ emission arises mainly from Eu incorporated inside the QDs while for the higher fluences only the emission from Eu inside the AlN-buffer, capping, and spacer layers is observed.
© 2010 American Institute of PhysicsFCT-PTDC/CTM/100756/2008program PESSOA EGIDE/GRICESFCT-SFRH/BD/45774/2008FCT-SFRH/BD/44635/200
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