3,843 research outputs found
Factors affecting the learning of English as a second language macroskills among Tongan secondary students
This study aimed at determining factors which might have impact on the learning of English as a second language macroskills (reading, writing, listening, and speaking) by Tongan secondary learners. The study was correlational in design and it worked from a synthetic perspective in that it looked at the way in which many aspects of language are interrelated to make the whole language system. The study looked at learning English language macroskills from a multiple interdisciplinary perspective taking into consideration linguistic, psycholinguistic, sociolinguistic factors and classroom and bilingual education perspectives. The framework for language use required the learner to know the grammar (linguistic competence) of English and also to have the knowledge of how to use it appropriately in a variety of contexts. The subjects of the study were 100 Form 5 ESL Secondary students and 24 Form 5 ESL Secondary teachers. The three main instruments used were a test and a questionnaire for the students and a questionnaire for the teachers. Students\u27 performance in the four English language macroskills were correlated with their perception of factors hypothesised to be associated with their learning of those English language macroskills at school (bivariate correlations). Standard multiple regressions were also performed (with only a few of the investigated factors selected as independent variables) to determine how much of the variance in the students\u27 performance can be accounted for by the selected variables. Seven factors were shown to have significant correlations with the students\u27 learning of English macroskills at secondary school. They were: the age of the students; their perceived ability in English; frequency of use of English with non-Tongan speakers; use of English to read for enjoyment; use of English for communication at home; integrative motivation; and career aspirations. The multiple regressions showed that 40% to 50% of the variances in reading, writing and listening could be accounted for by the same seven factors. All for speaking, 48.5% of the variance could be accounted for by five of these factors: age; perceived ability in English; frequency of use of English with non-Tongan speakers; use of English to read for enjoyment; and career aspirations. The findings of the study were accounted for in the light of appropriate and relevant linguistic theories
Organizational analysis of the seed sector of rice in Guinea: stakeholders, perception and institutional linkages
This paper analyses the organization of the rice seed sector in Guinea with the overall objectives to assess how organizational settings affect seed supply to small-scale farmers and to suggest institutional changes that would favour seed service and uptake of varieties. Data were collected in Guinea, West Africa, using focus group discussions with extension workers, farmers, representatives of farmers’ associations, agro-input dealers, researchers and non-governmental organization (NGO) staff, and surveys of 91 rice farming households and 41 local seed dealers. Findings suggest that the current institutional settings and perceptions of stakeholders from the formal seed sector inhibit smallholder farmers’ access to seed. Seed interventions in the past two decades have mainly relied on the national extension system, the research institute, NGOs, farmers’ associations and contract seed producers to ensure seed delivery. Although local seed dealers play a central role in providing seed to farmers, governmental organizations operating in a linear model of formal seed sector development have so far ignored their role. We discuss the need to find common ground and alternative models of seed sector development. In particular we suggest the involvement of local seed dealers in seed development activities to better link the formal and the informal seed systems and improve smallholder farmers’ access to seed from the formal sector
Effect of balconies on air quality in deep street canyons
This study discusses the effect of balconies on the dispersion of vehicular pollutants inside a deep street
canyon and on the mass transfer rate between the canyon and the above atmosphere. 3D computational
fluid dynamics (CFD) simulations were performed considering the presence of balconies of different
dimensions in a deep street canyon with aspect ratio H/W ÂĽ 3. The effect of two geometrical parameters
has been investigated: the balcony depth and the horizontal distance between two balconies, the other
geometrical parameters remaining constant. CFD simulations have been carried out adopting the scale
adaptive simulation (SAS) model. Results show that the presence of balconies can determine a significant
modification in the flow field inside the street canyon with a less homogeneous dispersion of pollutants
emitted by vehicles circulating in the street and a less effective mass exchange with the above atmosphere.
At the present models developed to assess pollutant concentration levels in street canyons do not
consider the presence of balconies. As consequence, an underestimation of real concentration levels
could occur. Therefore, results obtained can give a contribution in the development of more feasible air
pollution models in urban areas at local scale, and useful information for design of building facades that
minimize the entrapping of vehicular pollutants at pedestrian level in street canyon
Nanotube Piezoelectricity
We combine ab initio, tight-binding methods and analytical theory to study
piezoelectric effect of boron nitride nanotubes. We find that piezoelectricity
of a heteropolar nanotube depends on its chirality and diameter and can be
understood starting from the piezoelectric response of an isolated planar
sheet, along with a structure specific mapping from the sheet onto the tube
surface. We demonstrate that coupling between the uniaxial and shear
deformation are only allowed in the nanotubes with lower chiral symmetry. Our
study shows that piezoelectricity of nanotubes is fundamentally different from
its counterpart in three dimensional (3D) bulk materials.Comment: 4 pages, with 3 postscript figures embedded. Uses REVTEX4 macros.
Also available at
http://www.physics.upenn.edu/~nsai/preprints/bn_piezo/index.htm
Web-mediated communication experiences at Istituto Nazionale di Geofisica e Vulcanologia
The newer communication tools have changed the relationship between science and society. Internet
pervasiveness led citizens to rapidly inform through on line sources, and, on the other hand, to provide
themselves information. From an institutional communication' perspective this new sociotechnical
landscape forces scientists to rapidly adequate to web population requirements.
Questions and comments posted to INGV web sites during the 2009 L'Aquila (Italy) seismic sequence
gave significant hints about demand of information. They included: questions concerning possible
evolution of the sequence; clarifications about news reported by media, asking for detailed explanations
and/or qualified opinions; requests for help in providing information to population; notices about
information available on INGV web sites; communication of felt seismic effects.
P eople who post questions to INGV institutional web sites are themselves information suppliers, in
providing: what they felt, in case of posting macroseismic effects; what they heard about the earthquake
from other sources; how they feel (worried, confident, grateful ...); what they know and what they want to
know; what they actually understand from the scientific website.
From the point of view of a scientific organization, this kind of web-mediated communication is precious in
that it can reveal and provide many clues about: 1) public expectations and understanding of on going
scientific activities 2) to what extent information dissemination, communication and outreach activities
can be considered effective or to which extent they need improvements.
A mutual approaching is needed. Seismologists acting as responders during an emergency perform a
delicate job: they have to be transparent and make themselves understood; comprehension of scientific
information would benefit of appropriate outreach activities carried on during all the time.
Consisting the INGV web disseminating system of several institutional and thematic web sites, similar
patterns of questions and comments emerge: "network effect", when questions are posted at the end of a
navigation session through different web sites, and may not pertain to the content of that specific website;
"resonance effect", when more questions about earthquakes are posted soon after a big one. A "welcome"
effect is also manifest, as experts providing accurate replies in a timely fashion stimulate web visitors in
posting new questions.
Case studies of web-mediated communication will be discussed, as experimented by the Institute through
the nodes of its web disseminating system
Performance of the INGV National Seismic Network from 1997 to 2007
Seismic monitoring in Italy has strongly improved since the 1997 Umbria-Marche earthquake sequence. This has made the National Seismic Network (RSN) a powerful tool both to rapidly locate and quantify thousands of earthquakes occurring in Italy every year, and to study the seismic activity in detail, accumulating an impressive high quality data set that will be exploited in the coming years to understand earthquake processes and to investigate the deep structure.
This paper summarizes and compares the basic features of the seismicity recorded in 2000 and 2006, before and after the implementation of the new RSN, showing that the number of well located earthquakes has more than doubled and that the completeness magnitude has dropped from ~2.3 to ~1.7. In addition, we concentrate on the evaluation of the current automatic location and magnitudes versus the revised ones, published routinely in the INGV bulletins. We show that the rapid estimates of locations and magnitudes are robust and reliable for most regions in Italy: more than 75% of the earthquakes are located in real time within 10km from the «true» locations, whereas the rapid magnitudes ML are within ±0.4 from the revised values in 90% of cases. The comparison between real-time and revised locations shows that there are a few regions in Italy where a further network improvement is still desirable. These include all the off-shore regions, Calabria, western Sicily, the Alpine and Po Plain region, and some small areas along the peninsula
Task 3- Deliverable 5
Il data-base dei dati accelerometrici italiani (Italian Strong Motion Data Base) copre un periodo di tempo di oltre 20 anni durante i quali non solo le reti sismiche italiane hanno subito una evoluzione notevolissima, ma l’intera sismologia mondiale e la tecnologia ad essa applicata è stata completamente rivoluzionata. La rete Sismica Nazionale gestita dall’INGV (ING fino al 1999), è cresciuta da 12 strumenti riportati nei bollettini del 1972 a oltre 180 nel 2004. Il Bollettino Sismico Italiano dell’anno 1972 include le fasi di 6 sismometri per un terremoto di magnitudo 5 avvenuto al largo di Ancona il 14 giugno 1972. Un terremoto di magnitudo analoga avvenuto il 25 novembre 2004 nell’Adriatico centrale, ben più lontano del precedente dalle coste italiane, è stato registrato da oltre 70 stazioni della Rete Sismica Nazionale. Occorre tenere presente questi dati nell’utilizzo del data-base accelerometrico perché la precisione con cui sono stati valutati i parametri ipocentrali dei terremoti è variata nell’arco di tempo coperto dal data-base di un ordine di grandezza
Snake states and their symmetries in graphene
Snake states are open trajectories for charged particles propagating in two
dimensions under the influence of a spatially varying perpendicular magnetic
field. In the quantum limit they are protected edge modes that separate
topologically inequivalent ground states and can also occur when the particle
density rather than the field is made nonuniform. We examine the correspondence
of snake trajectories in single-layer graphene in the quantum limit for two
families of domain walls: (a) a uniform doped carrier density in an
antisymmetric field profile and (b) antisymmetric carrier distribution in a
uniform field. These families support different internal symmetries but the
same pattern of boundary and interface currents. We demonstrate that these
physically different situations are gauge equivalent when rewritten in a Nambu
doubled formulation of the two limiting problems. Using gauge transformations
in particle-hole space to connect these problems, we map the protected
interfacial modes to the Bogoliubov quasiparticles of an interfacial
one-dimensional p-wave paired state. A variational model is introduced to
interpret the interfacial solutions of both domain wall problems
A completeness analysis of the national seismic network of Italy
We present the first detailed study of earthquake detection capabilities of the Italian National Seismic Network and of the completeness threshold of its earthquake catalog. The network in its present form started operating on 16 April 2005 and is a significant improvement over the previous networks. For our analysis, we employed the PMC method as introduced by Schorlemmer and Woessner (2008). This method does not estimate completeness from earthquakes samples as traditional methods, mostly based on the linearity of earthquake-size distributions. It derives detection capabilities for each station of the network and synthesizes them into maps of detection probabilities for earthquakes of a given magnitude. Thus, this method avoids the many assumptions about earthquake distributions that traditional methods make. The results show that the Italian National Seismic Network is complete at M=2.9 for the entire territory excluding the islands of Sardinia, Pantelleria, and Lampedusa. At the M=2.5 level, which is the reporting threshold level of the Italian Civil Protection, the network may miss events in southern parts of Apulia and the western part of Sicily. The stations are connected through many different telemetry links to the operational datacenter in Rome. Scenario computations show that no significant drop in completeness occurs if one of the three major links fail, indicating a well-balanced network setup
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