1,361 research outputs found
Estimation of losses for adobe buildings in Pakistan
Adobe buildings are vulnerable to seismic forces. Large scale destructions and casualties have been caused due
to the collapse of adobe buildings during the past earthquakes. A significant number of adobe structures exist in
different parts of Pakistan, similar to other parts of the world. Since Pakistan lies in a seismic active region, it is
necessary to assess the level of vulnerability of these buildings in order to estimate associated losses during a
seismic event. This paper presents the results of a study which was conducted to quantify damages to adobe
buildings based on their fragility curves. The adobe buildings were found to be highly vulnerable to low intensity
earthquakes. The vulnerability of these buildings has been compared with the European adobe buildings. It was
noted that Pakistani adobe buildings were slightly less resistant to earthquakes as compared to similar buildings
in Europe. Retrofitting solutions were suggested in order to increase the seismic capacity of adobe buildings in
Pakistan
Empirical analysis of vegetation dynamics and the possibility of a catastrophic desertification transition
The process of desertification in the semi-arid climatic zone is considered
by many as a catastrophic regime shift, since the positive feedback of
vegetation density on growth rates yields a system that admits alternative
steady states. Some support to this idea comes from the analysis of static
patterns, where peaks of the vegetation density histogram were associated with
these alternative states. Here we present a large-scale empirical study of
vegetation dynamics, aimed at identifying and quantifying directly the effects
of positive feedback. To do that, we have analyzed vegetation density across
of the African Sahel region, with spatial
resolution of meters, using three consecutive snapshots. The
results are mixed. The local vegetation density (measured at a single pixel)
moves towards the average of the corresponding rainfall line, indicating a
purely negative feedback. On the other hand, the chance of spatial clusters (of
many "green" pixels) to expand in the next census is growing with their size,
suggesting some positive feedback. We show that these apparently contradicting
results emerge naturally in a model with positive feedback and strong
demographic stochasticity, a model that allows for a catastrophic shift only in
a certain range of parameters. Static patterns, like the double peak in the
histogram of vegetation density, are shown to vary between censuses, with no
apparent correlation with the actual dynamical features
Assessment of seismic performance of adobe structures in Pakistan and Portugal
Adobe buildings exist in different parts of the world. The construction of these buildings can be carried out
economically, using locally available materials and skills that do not require use of modern machinery.
Therefore, adobe buildings provide an economic housing option. The construction of adobe structures is carried
out based on traditional construction practices which vary from region to region. This paper presents the results
of a study which was conducted to study the construction practices of adobe buildings in Pakistan and Portugal
in the context of their seismic vulnerability. The adobe buildings in both these countries were found to be
subjected to seismic hazard levels which, although is low in some regions, may cause significant damages. Lack of essential elements or details for the adequate seismic performance was found in the adobe buildings in both regions
Weak Kaon Production off the Nucleon
The weak kaon production off the nucleon induced by neutrinos is studied at
the low and intermediate energies of interest for some ongoing and future
neutrino oscillation experiments. This process is also potentially important
for the analysis of proton decay experiments. We develop a microscopical model
based on the SU(3) chiral Lagrangians. The basic parameters of the model are
fpi, the pion decay constant, Cabibbo's angle, the proton and neutron magnetic
moments and the axial vector coupling constants for the baryons octet, D and F,
that are obtained from the analysis of the semileptonic decays of neutron and
hyperons. The studied mechanisms are the main source of kaon production for
neutrino energies up to 1.2 to 1.5 GeV for the various channels and the cross
sections are large enough to be amenable to be measured by experiments such as
Minerva and T2K
Antineutrino induced antikaon production off the nucleon
The charged current antikaon production off nucleons induced by antineutrinos
is studied at low and intermediate energies. We extend here our previous
calculation on kaon production induced by neutrinos. We have developed a
microscopic model that starts from the SU(3) chiral Lagrangians and includes
background terms and the resonant mechanisms associated to the lowest lying
resonance in the channel, namely, the Sigma*(1385). Our results could be of
interest for the background estimation of various neutrino oscillation
experiments like MiniBooNE and SuperK. They can also be helpful for the planned
antineutrino experiments like MINERvA, NOvA and T2K phase II and for beta-beam
experiments with antineutrino energies around 1 GeV.Comment: 15 pages and 6 figures. This version matches accepted version for
publication in Physical Review
Weak Production of Strange Particles and Mesons off the Nucleon
The strange particle production induced by (anti)neutrino off nucleon has
been studied for and channels.
The reactions those we have considered are for the production of single
kaon/antikaon, eta and associated particle production processes.
We have developed a microscopical model based on the SU(3) chiral Lagrangian.
The basic parameters of the model are , the pion decay constant, Cabibbo
angle, the proton and neutron magnetic moments and the axial vector coupling
constants for the baryons octet. For antikaon production we have also included
(1385) resonance and for eta production (1535) and
(1650) resonances are included.Comment: To appear in AIP Conf. Proc. of the Workshop CETUP*14, 12 Pages, 13
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