905 research outputs found
Train unit scheduling with bi-level capacity requirements
Train unit scheduling concerns the assignment of train unit vehicles to cover all the journeys in a fixed timetable allowing the possibility of coupling and decoupling to achieve optimal utilization while satisfying passenger demands. While the scheduling methods usually assume unique and well-defined train capacity requirements, in practice most UK train operators consider different levels of capacity provisions. Those capacity provisions are normally influenced by information such as passenger count surveys, historic provisions and absolute minimums required by the authorities. In this paper, we study the problem of train unit scheduling with bi-level capacity requirements and propose a new integer multicommodity flow model based on previous researches. Computational experiments on real-world data show the effectiveness of our proposed methodology
Comparison of molecular patterns and virulence behaviour of potato cyst nematodes
Sept populations de nématodes à kyste de la pomme de terre (#Globodera rostochiensis et #G. pallida) ont été analysées au moyen de marqueurs provenant de fragments d'ADN amplifiés au hasard (RAPD), d'amorces de microsatellites amplifiés en chaîne par réaction de polymérase (PCR) et d'électrophorèse de protéines totales en deux dimensions sur gel. Un degré élevé de polymorphisme a été détecté chez tous les types de marqueurs. De plus, des réactions de virulence des populations et de l'hôte, de même qu'une interaction hautement significative entre ces deux variables, ont été observés. Les distances génétiques entre populations de nématodes, fondées sur les données moléculaires et les réactions de virulence ont été estimées. Des analyses en grappes ont été réalisées et les matrices de distance en résultant comparées. Une bonne consistance entre les différents dendrogrammes, de même que des coefficients de corrélation hautement significatifs ont été observés lorsque l'on a comparé les matrices de distance dérivées des données moléculaires, et les réactions de virulence. L'application pratique de telles analyses moléculaires à l'étude des populations de nématodes permettrait d'obtenir des tests indirects de virulence et donc de pouvoir recommander les cultivars appropriés de pomme de terre dans le cas de sols infestés. (Résumé d'auteur
Estructura y morfología de las regiones degradadas del polietileno de ultra alto peso molecular en prótesis articulares
Se realiza el presente estudio en material de 3 prótesis articulares de rodilla para valorar las diferencias morfológicas y estructurales entre las zonas degradadas y no degradadas encontradas en el polietileno de ultra alto peso molecular (PEUAPM). Los implantes estudiados comprenden material degradado tras implante y retirada, material degradado sin implantar y material no
degradado sin implantar. Mediante microscopía electrónica de barrido, se analiza la morfología de la zona degradada que explica la pérdida de transparencia del material en la llamada banda blanca.
Mediante FTIR, se comprueba la degradación química de la zona de banda y se obtiene el índice de
degradación del material, correlacionado con su cristalinidad. Mediante DSC y difractogramas de
rayos X, se manifiesta en el material degradado la presencia de fase ortorrómbica pero también
monoclínica, cuya cuantificación mediante rayos X abre un nuevo camino para investigar la relación
entre degradación del material y fracaso del implante.Peer Reviewe
Fossil group origins - VI. Global X-ray scaling relations of fossil galaxy clusters
We present the first pointed X-ray observations of 10 candidate fossil galaxy
groups and clusters. With these Suzaku observations, we determine global
temperatures and bolometric X-ray luminosities of the intracluster medium (ICM)
out to for six systems in our sample. The remaining four systems show
signs of significant contamination from non-ICM sources. For the six objects
with successfully determined properties, we measure global
temperatures in the range ,
bolometric X-ray luminosities of , and estimate masses,
as derived from , of .
Fossil cluster scaling relations are constructed for a sample that combines our
Suzaku observed fossils with fossils in the literature. Using measurements of
global X-ray luminosity, temperature, optical luminosity, and velocity
dispersion, scaling relations for the fossil sample are then compared with a
control sample of non-fossil systems. We find the fits of our fossil cluster
scaling relations are consistent with the relations for normal groups and
clusters, indicating fossil clusters have global ICM X-ray properties similar
to those of comparable mass non-fossil systems.Comment: 17 pages, 7 figures, 8 tables. Accepted for publication in MNRA
VGCF Detection of Galaxy Systems at Intermediate Redshift
We continue the development of our Voronoi Galaxy Cluster Finder (VGCF)
technique by applying it to galaxy catalogs obtained with B and R band
observations of four high galactic latitude fields of 0.5x0.5 square degrees
each. These fields are deep R_lim ~23, B_lim ~26 and partially overlap the
Palomar Distant Cluster Survey (PDCS) fields at 0h and 2h. We run the VGCF also
on the original V and I bands PDCS galaxy catalogs.
We identify a total of 48 clusters that are particularly reliable being
detected in at least two bands. The analysis of color-magnitude diagrams and,
in a few cases, spectroscopic observations allow us to further increase the
reliability of 25 of the 48 clusters. For these 26 clusters we also estimate
redshifts that fall in the approximate range 0.2 < z < 0.6.
We detect 41 VGCF clusters within the strict limits of the PDCS fields at 0h
and 2h. The PDCS catalog for the same regions consists of 28 clusters. The two
catalogs have 20 clusters in common. These clusters together with the remaining
PDCS and VGCF clusters lead to a total number of 46 "independent" clusters. The
total number of clusters is therefore 20% larger than the number of VGCF
clusters and more than 60% larger than the number of PDCS clusters. These
results confirm a) that the VGCF is a competitive algorithm for the
identification of optical clusters, and b) that a combined catalog of
matched-filter and VGCF clusters constitutes a significant progress toward a
more complete selection of clusters from bidimensional optical data.Comment: 15 pages, 6 figures, accepted in A&
Cluster Abell 520: a perspective based on member galaxies. A cluster forming at the crossing of three filaments?
The connection of cluster mergers with the presence of extended, diffuse
radio sources in galaxy clusters is still debated. An interesting case is the
rich, merging cluster Abell 520, containing a radio halo. A recent
gravitational analysis has shown in this cluster the presence of a massive dark
core suggested to be a possible problem for the current cold dark matter
paradigm.
We aim to obtain new insights into the internal dynamics of Abell 520
analyzing velocities and positions of member galaxies.
Our analysis is based on redshift data for 293 galaxies in the cluster field
obtained combining new redshift data for 86 galaxies acquired at the TNG with
data obtained by CNOC team and other few data from the literature. We also use
new photometric data obtained at the INT telescope. We combine galaxy
velocities and positions to select 167 cluster members around z~0.201. We
analyze the cluster structure using the weighted gap analysis, the KMM method,
the Dressler-Shectman statistics and the analysis of the velocity dispersion
profiles. We compare our results with those from X-ray, radio and gravitational
lensing analyses.
We find that Abell 520 is definitely a very complex system. Our results
suggest that we are looking at a cluster forming at the crossing of three
filaments of the large scale structure. In particular, we detect a filament
aligned with the LOS and projected onto the center of the forming cluster. It
might explain the apparent massive dark core shown by gravitational lensing
analysis.Comment: 18 pages, 16 figures, 4 tables. Accepted for publication on A&
Fossil group origins V. The dependence of the luminosity function on the magnitude gap
In nature we observe galaxy aggregations that span a wide range of magnitude
gaps between the two first-ranked galaxies of a system (). There
are systems with gaps close to zero (e.g., the Coma cluster), and at the other
extreme of the distribution, the largest gaps are found among the so-called
fossil systems. Fossil and non-fossil systems could have different galaxy
populations that should be reflected in their luminosity functions. In this
work we study, for the first time, the dependence of the luminosity function
parameters on using data obtained by the fossil group origins
(FOGO) project. We constructed a hybrid luminosity function for 102 groups and
clusters at . We stacked all the individual luminosity functions,
dividing them into bins of , and studied their best-fit
Schechter parameters. We additionally computed a relative luminosity function,
expressed as a function of the central galaxy luminosity, which boosts our
capacity to detect differences, especially at the bright end. We find trends as
a function of at both the bright and faint ends of the
luminosity function. In particular, at the bright end, the larger the magnitude
gap, the fainter the characteristic magnitude . We also find
differences at the faint end. In this region, the larger the gap, the flatter
the faint-end slope . The differences found at the bright end support a
dissipationless, dynamical friction-driven merging model for the growth of the
central galaxy in group- and cluster-sized halos. The differences in the faint
end cannot be explained by this mechanism. Other processes, such as enhanced
tidal disruption due to early infall and/or prevalence of eccentric orbits, may
play a role. However, a larger sample of systems with is
needed to establish the differences at the faint end.Comment: 11 pages, 10 figures, accepted for publication in A&
Sonication of intramedullary nails: Clinically-related infection and contamination
Background and Aim: Sonication is currently considered the best procedure for microbiological diagnosis of
implant-related osteoarticular infection, but studies in nail-related infections are lacking. The study aim was to evaluate
implant sonication after intramedullary nail explantation, and relate it to microbiological cultures and clinical outcome.
Patients and Methods: A study was performed in two University Hospitals from the same city. Thirty-one patients with
implanted nails were prospectively included, whether with clinical infection (8 cases) or without (23 cases). Retrieved
nails underwent sonication according a previously published protocol. The clinical and microbiological outcome patient
was related to the presence of microorganisms in the retrieved implant.
Results: Positive results appeared in 15/31 patients (9 with polymicrobial infections) almost doubling those clinically
infected cases. The most commonly isolated organisms were Staphylococcus epidermidis (19.2 %) and Staphylococcus
aureus (15.4 %). A significant relationship was found between the presence of positive cultures and previous local
superficial infection (p=0.019). The presence of usual pathogens was significantly related to clinical infection (p=0.005)
or local superficial infection (p=0.032). All patients with positive cultures showed pain diminution or absence of pain after
nail removal (15/15), but this only occurred in 8 (out of 16) patients with negative cultures.
Conclusions: In patients with previously diagnosed infection or local superficial infection, study of the hardware is
mandatory. In cases where pain or patient discomfort is observed, nail sonication can help diagnose the implant
colonization with potential pathogens that might require specific treatment to improve the final outcomePart of this work was funded by grants from the
Comunidad de Madrid (S2009/MAT-1472) and from the
CONSOLIDER-INGENIO Program (FUNCOAT-CSD2008-
00023). DMM was funded by a grant from the Fundación
Conchita Rábago de Jiménez Día
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