449 research outputs found
Accessibility impacts of tod experiences in European metropolitan areas
The study investigates how Transit Oriented Development - TOD structure affect accessibility in cities with the aim of establishing whether TOD patterns of urban expansion, in terms of network connectivity and inhabitants and job density, could be associated with measures of rail accessibility. In particular the paper addresses the following overarching questions: is TOD informed structure related to high accessibility by rail public transport? Which features of TOD structure affect accessibility? The paper provides a cross- comparative empirical analysis of six metropolitan areas in Europe, where the TOD degree is measured as the amount of urban development clustering along rail corridors and stations; this feature is then related to cumulative opportunity measures of accessibility to jobs and inhabitants. The research demonstrate that accessibility increases in cities that are developed around the rail network and with higher value of network connectivity, but no correlation is found between accessibility and mean density values. The research furthermore provide an application of the node-place model demonstrating its useful potential in accessibility planning processes
Aspects of symmetry breaking in SO(10) GUTs
I review some recent results on the Higgs sector of minimal SO(10) grand
unified theories both with and without supersymmetry. It is shown that
nonsupersymmetric SO(10) with just one adjoint triggering the first stage of
the symmetry breaking does provide a successful gauge unification when
radiative corrections are taken into account in the scalar potential, while in
the supersymmetric case it is argued that the troubles in achieving a
phenomenologically viable breaking with representations up to the adjoint are
overcome by considering the flipped SO(10) embedding of the hypercharge.Comment: 8 pages, 1 figure; prepared for the proceedings of DISCRETE'10 -
Symposium on Prospects in the Physics of Discrete Symmetrie
A comparison of four different methods to estimate population size of Alpine marmot (Marmota marmota)
Obtaining reliable information on animal abundance in mountainous landscapes is challenging. Highly heterogeneous habitats tend to reduce detection probabilities, and the three-dimensional, rugged nature of the terrain poses severe limits to the fulfilment of a number of assumptions underlying several statistical methods. In this study, we aimed to compare the performance of 4 different methods to estimate population size of Alpine marmot (Marmota marmota), a highly social semifossorial rodent widely distributed on the European Alps. Between May and August 2015, in a study area within the Stelvio National Park (Italy) we conducted 8 sessions of capture-mark-recapture, 6 sessions of mark-resight from vantage points, 8 sessions of line distance sampling along 4 transects, and 2 sessions using double-observer methods from vantage points. The minimum number of animals alive, obtained during the mark-resight surveys, was n=54 individuals. Capture-mark-recapture models estimated a population size of n=56 individuals [95% CI (45,87)]; similar, but more precise estimates were obtained with the mark-resight approach {Bowden’s estimator: n=62 [95% CI (54,71)]; Poisson log-normal estimator: n=62 [95% CI (55,69)]}. Line distance sampling and double-observer methods were severely biased low {Line distance sampling: n=24 individuals [95% CI (19,31)]; Independent double-observer: n=24 [95% CI (22, 35)]; Dependent double-observer: n=15 [95% CI (15,20)]}. Our results suggest that the probabilistic approach based on marked individuals yielded fairly robust estimates of population size. The underestimates obtained using distance sampling and double-observer methods were likely due to the violation of some underlying assumptions. While the topography of the mountainous landscape makes it difficult to randomize the sampling scheme, the semifossorial behaviour of the target species is likely to lower the detection probabilities and violate the assumption of perfect detection on the transect
Seesaw Scale in the Minimal Renormalizable SO(10) Grand Unification
Simple SO(10) Higgs models with the adjoint representation triggering the
grand-unified symmetry breaking, discarded a long ago due to inherent
tree-level tachyonic instabilities in the physically interesting scenarios,
have been recently brought back to life by quantum effects. In this work we
focus on the variant with 45_H+126_H in the Higgs sector and show that there
are several regions in the parameter space of this model that can support
stable unifying configurations with the B-L breaking scale as high as 10^14
GeV, well above the previous generic estimates based on the minimal survival
hypothesis. This admits for a renormalizable implementation of the canonical
seesaw and makes the simplest potentially realistic scenario of this kind a
good candidate for a minimal SO(10) grand unification. Last, but not least,
this setting is likely to be extensively testable at future large-volume
facilities such as Hyper-Kamiokande.Comment: 21 pages, 9 figures, 5 table
Structure and prospects of the simplest SO(10) GUTs
We recapitulate the latest results on the class of the simplest SO(10) grand
unified models in which the GUT-scale symmetry breaking is triggered by an
adjoint Higgs representation. We argue that the minimal survival approximation
traditionally used in the GUT- and seesaw-scale estimates tends to be blind to
very interesting parts of the parameter space in which some of the
intermediate-scale states necessary for non-supersymmetric unification of the
SM gauge couplings can be as light as to leave their imprints in the TeV
domain. The stringent minimal-survival-based estimates of the B-L scale are
shown to be relaxed by as much as four orders of magnitude, thus admitting for
a consistent implementation of the standard seesaw mechanism even without
excessive fine-tuning implied by the previous studies. The prospects of the
minimal renormalizable SO(10) GUT as a potential candidate for a
well-calculable theory of proton decay are discussed in brief.Comment: 9 pages, 6 figures; to appear in the proceedings of the CETUP'12
worksho
Vascular and Cardiac CT in Small Animals
Computed tomography (CT) is increasingly available in veterinary practice. As for humans, CT has a tremendous potential in various clinical scenario. Oncology and traumatized dogs and cats are probably the veterinary patients that get more benefit from new CT applications. However, the most amazing progresses are in vascular and cardiac applications. The advent and rapid diffusion of advanced scanner technology (multidetector row) offer unparalleled diagnostic opportunity in daily practice for comprehensive evaluation of complex cardiovascular diseases. New skills and knowledge are necessary for radiologists and nonradiologists for understanding this revolutionary field of radiology
Direct CP Violation in B->phi K_s and New Physics
In the presence of large New Physics contributions to loop-induced b->s
transitions, sizable direct CP violation in B-> phi K decays is expected on
general grounds. We compute explicitly CP-violating effects using QCD
factorization and find that, even in the restricted case in which New Physics
has the same penguin structure as the Standard Model, the rate asymmetry can be
of order one. We briefly discuss a more general scenario and comment on the
inclusion of power-suppressed corrections to factorization.Comment: 3 page
Investigation on the effect of supplementary cementitious materials on the critical chloride threshold of steel in concrete
open3noThe critical chloride threshold is a key parameter in the service life design of reinforced concrete structures exposed to chloride-bearing environments. This paper investigates the role of concrete composition, and particularly the effect of supplementary cementing materials, on the chloride threshold. To simulate real exposure conditions, ponding tests were carried out on reinforced concrete specimens with bars in free corrosion conditions and corrosion initiation was detected through corrosion potential and corrosion rate measurements. After two and a half years, the ponding was followed by an ageing period and the initiation of corrosion was further detected with anodic potentiostatic polarisation tests. Results of the tests showed several limitations of the approach based on chloride penetration and monitoring of free corrosion parameters to investigate the chloride threshold. In spite of this, a possible role of natural pozzolan and coal fly ash additions in leading to higher values of the chloride threshold and ground limestone in promoting lower values of the chloride threshold could be observed.Lollini, Federica; Redaelli, Elena; Bertolini, LucaLollini, Federica; Redaelli, Elena; Bertolini, Luc
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