6,807 research outputs found
Exposing the human nude phenotype [4]
Peer reviewedSubmitted Versio
Evaluating a Second Life PBL Demonstrator Project: What Can We Learn?
This article reports the findings of a demonstrator project to evaluate how effectively Immersive Virtual Worlds (IVWs) could support Problem-based Learning. The project designed, created and evaluated eight scenarios within Second Life (SL) for undergraduate courses in health care management and paramedic training. Evaluation was primarily qualitative, using illuminative evaluation which provided multiple perspectives through interviews, focus groups and questionnaires with designers, facilitators, learning technologists and students. Results showed that SL provided a rich, engaging environment which enhanced authenticity of the scenarios, though there were issues of access and usability. The article concludes by drawing together the lessons learned which will inform educators who seek to design and develop learning scenarios in this medium
Listado anotado de Solanum L. (Solanaceae) en el Peru.
The genus Solanum is among the most species-rich genera both of the Peruvian flora and of the tropical Andes in general. The present revised checklist treats 276 species of Solanum L., of which 253 are native, while 23 are introduced and/or cultivated. A total of 74 Solanum species (29% of native species) are endemic to Peru. Additional 58 species occur only in small number of populations outside Peru, and these species are here labelled as near-endemics to highlight the role Peru playes in their future protection. Species diversity is observed to peak between 2500 – 3000 m elevation, but endemic species diversity is highest between 3000 – 3500 m elevation. Cajamarca has the highest number of endemic (29 spp.) and total species (130 spp.), even when considering the effect of area. Centers of endemic species diversity are observed in provinces of Cajamarca (Cajamarca), Huaraz and Carhuaz (Ancash), and Canta and Huarochirí (Lima). Secondary centres of endemism with high concentrations of both endemics and near-endemics are found in San Ignacio and Cutervo (Cajamarca), Santiago de Chuco (La Libertad), Oxapampa (Pasco), and Cusco (Cusco). Current diversity patterns are highly correlated with collection densities, and further collecting is needed across all areas, especially from Arequipa, Ayacucho, Puno, Ancash, Huánuco, Amazonas and Cajamarca, where high levels of species diversity and endemism are indicated but only a few collections of many species are known.Solanum L. es uno de los géneros que posee una alta riqueza de especies dentro de la flora peruana y dentro de los Andes tropicales en general. Presentamos una lista revisada de 276 especies de Solanum para el Perú, de estas 253 son nativas, mientras que 23 son introducidas y/o cultivadas. Un total de 74 especies de Solanum (29% de las especies nativas) son endémicas de Perú. Además 58 especies se encuentran solamente en pequeñas poblaciones fuera del Perú, y estas especies están designadas aquí como casi endémicas para destacar el rol importante del Perú en la futura protección de estas especies. El pico de diversidad de especies es observado entre 2500 – 3000 m de elevación, pero la diversidad de especies endémicas es más alta entre 3000 – 3500 m. Cajamarca tiene el más alto número de especies (130 spp.) y de especies endémicas (29 spp.), incluso si se considera el efecto del área. Centros de diversidad de especies endémicas se localizan en las provincias de Cajamarca (Cajamarca), Huaraz y Carhuaz (Ancash), Canta y Huarochirí (Lima). Centros de endemismos secundarios con una alta concentración tanto de especies endémicas y de casi endémicas se encuentran en San Ignacio y Cutervo (Cajamarca), Santiago de Chuco (La Libertad), Oxapampa (Pasco), y Cusco (Cusco): Los actuales patrones de diversidad están altamente correlacionados con la densidad de colecciones, por lo que es necesario una mayor colecta en todas las regiones, especialmente en Arequipa, Ayacucho, Puno, Ancash, Huánuco, Amazonas y Cajamarca, donde se indican altos niveles de diversidad y endemismo de especies, pero de las cuales existen pocas colecciones
Spin observables in deuteron-proton radiative capture at intermediate energies
A radiative deuteron-proton capture experiment was carried out at KVI using
polarized-deuteron beams at incident energies of 55, 66.5, and 90 MeV/nucleon.
Vector and tensor-analyzing powers were obtained for a large angular range. The
results are interpreted with the help of Faddeev calculations, which are based
on modern two- and three-nucleon potentials. Our data are described well by the
calculations, and disagree significantly with the observed tensor anomaly at
RCNP.Comment: 10 pages, 4 figures, submitted to PL
Neutrons from multiplicity-selected La-La and Nb-Nb collisions at 400A MeV and La-La collisions at 250A MeV
Triple-differential cross sections for neutrons from high-multiplicity La-La
collisions at 250 and 400 MeV per nucleon and Nb-Nb collisions at 400 MeV per
nucleon were measured at several polar angles as a function of the azimuthal
angle with respect to the reaction plane of the collision. The reaction plane
was determined by a transverse-velocity method with the capability of
identifying charged-particles with Z=1, Z=2, and Z > 2. The flow of neutrons
was extracted from the slope at mid-rapidity of the curve of the average
in-plane momentum vs the center-of-mass rapidity. The squeeze-out of the
participant neutrons was observed in a direction normal to the reaction plane
in the normalized momentum coordinates in the center-of-mass system.
Experimental results of the neutron squeeze-out were compared with BUU
calculations. The polar-angle dependence of the maximum azimuthal anisotropy
ratio was found to be insensitive to the mass of the colliding
nuclei and the beam energy. Comparison of the observed polar-angle dependence
of the maximum azimuthal anisotropy ratio with BUU calculations for
free neutrons revealed that is insensitive also to the
incompressibility modulus in the nuclear equation of state.Comment: ReVTeX, 16 pages, 17 figures. To be published in Physical Review
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Problem-based learning approaches in meteorology
Problem-Based Learning, despite recent controversies about its effectiveness, is used extensively as a teaching method throughout higher education. In meteorology, there has been little attempt to incorporate Problem-Based Learning techniques into the curriculum. Motivated by a desire to enhance the reflective engagement of students within a current field course module, this project describes the implementation of two test Problem-Based Learning activities and testing and improvement using several different and complementary means of evaluation. By the end of a 2-year program of design, implementation, testing, and reflection and re-evaluation, two robust, engaging activities have been developed that provide an enhanced and diverse learning environment in the field course. The results suggest that Problem-Based Learning techniques would be a useful addition to the meteorology curriculum and suggestions for courses and activities that may benefit from this approach are included in the conclusions
Azimuthal Correlations in the Target Fragmentation Region of High Energy Nuclear Collisions
Results on the target mass dependence of proton and pion pseudorapidity
distributions and of their azimuthal correlations in the target rapidity range
are presented. The data have been taken with the
Plastic-Ball detector set-up for 4.9 GeV p + Au collisions at the Berkeley
BEVALAC and for 200 GeV/ p-, O-, and S-induced reactions on
different nuclei at the CERN-SPS. The yield of protons at backward rapidities
is found to be proportional to the target mass. Although protons show a typical
``back-to-back'' correlations, a ``side-by-side'' correlation is observed for
positive pions, which increases both with target mass and with impact parameter
of a collision. The data can consistently be described by assuming strong
rescattering phenomena including pion absorption effects in the entire excited
target nucleus.Comment: 7 pages, figures included, complete postscript available at
ftp://qgp.uni-muenster.de/pub/paper/azi-correlations.ps submitted to Phys.
Lett.
Wanted dead or alive : high diversity of macroinvertebrates associated with living and ’dead’ Posidonia oceanica matte
The Mediterranean endemic seagrass Posidonia
oceanica forms beds characterised by a dense leaf canopy
and a thick root-rhizome ‘matte’. Death of P. oceanica
shoots leads to exposure of the underlying matte, which
can persist for many years, and is termed ‘dead’ matte.
Traditionally, dead matte has been regarded as a degraded
habitat. To test whether this assumption was
true, the motile macroinvertebrates of adjacent living
(with shoots) and dead (without shoots) matte of
P. oceanica were sampled in four different plots located
at the same depth (5–6 m) in Mellieha Bay, Malta
(central Mediterranean). The total number of species
and abundance were significantly higher (ANOVA;
P<0.05 and P<0.01, respectively) in the dead matte
than in living P. oceanica matte, despite the presence of
the foliar canopy in the latter. Multivariate analysis
(MDS) clearly showed two main groups of assemblages,
corresponding to the two matte types. The amphipods
Leptocheirus guttatus and Maera grossimana, and the
polychaete Nereis rava contributed most to the dissimilarity
between the two different matte types. Several
unique properties of the dead matte contributing to the
unexpected higher number of species and abundance of
motile macroinvertebrates associated with this habitat
are discussed. The findings have important implications
for the conservation of bare P. oceanica matte, which
has been generally viewed as a habitat of low ecological
value.peer-reviewe
Artificial drainage of peatlands: hydrological and hydrochemical process and wetland restoration
Peatlands have been subject to artificial drainage for centuries. This drainage has been in response to agricultural demand, forestry, horticultural and energy properties of peat and alleviation of flood risk. However, the are several environmental problems associated with drainage of peatlands. This paper describes the nature of these problems and examines the evidence for changes in hydrological and hydrochemical processes associated with these changes. Traditional black-box water balance approaches demonstrate little about wetland dynamics and therefore the science of catchment response to peat drainage is poorly understood. It is crucial that a more process-based approach be adopted within peatland ecosystems. The environmental problems associated with peat drainage have led, in part, to a recent reversal in attitudes to peatlands and we have seen a move towards wetland restoration. However, a detailed understanding of hydrological, hydrochemical and ecological process-interactions will be fundamental if we are to adequately restore degraded peatlands, preserve those that are still intact and understand the impacts of such management actions at the catchment scale
Search for Production via Trilepton Final States in collisions at TeV
We have searched for associated production of the lightest chargino,
, and next-to-lightest neutralino, , of the
Minimal Supersymmetric Standard Model in collisions at
\mbox{ = 1.8 TeV} using the \D0 detector at the Fermilab Tevatron
collider. Data corresponding to an integrated luminosity of 12.5 \ipb
were examined for events containing three isolated leptons. No evidence for
pair production was found. Limits on
BrBr are
presented.Comment: 17 pages (13 + 1 page table + 3 pages figures). 3 PostScript figures
will follow in a UUEncoded, gzip'd, tar file. Text in LaTex format. Submitted
to Physical Review Letters. Replace comments - Had to resumbmit version with
EPSF directive
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