6,358 research outputs found
Business and Information Technology Alignment Measurement -- a recent Literature Review
Since technology has been involved in the business context, Business and
Information Technology Alignment (BITA) has been one of the main concerns of IT
and Business executives and directors due to its importance to overall company
performance, especially today in the age of digital transformation. Several
models and frameworks have been developed for BITA implementation and for
measuring their level of success, each one with a different approach to this
desired state. The BITA measurement is one of the main decision-making tools in
the strategic domain of companies. In general, the classical-internal alignment
is the most measured domain and the external environment evolution alignment is
the least measured. This literature review aims to characterize and analyze
current research on BITA measurement with a comprehensive view of the works
published over the last 15 years to identify potential gaps and future areas of
research in the field.Comment: 12 pages, Preprint version, BIS 2018 International Workshops, Berlin,
Germany, July 18 to 20, 2018, Revised Paper
On the universality of density profiles
We use the secondary infall model described in Del Popolo (2009), which takes
into account the effect of dynamical friction, ordered and random angular
momentum, baryons adiabatic contraction and dark matter baryons interplay, to
study how in- ner slopes of relaxed LCDM dark matter (DM) halos with and
without baryons (baryons+DM, and pure DM) depend on redshift and on halo mass.
We apply the quoted method to structures on galactic scales and clusters of
galaxies scales. We find that the inner logarithmic density slope, of dark
matter halos with baryons has a significant dependence on halo mass and
redshift with slopes ranging from 0 for dwarf galaxies to 0.4 for objects of M
= 10^13M_solar and 0.94 for M = 10^15M_solar clusters of galaxies. Structures
slopes increase with increasing redshift and this trend reduces going from
galaxies to clusters. In the case of density profiles constituted just of dark
matter the mass and redshift dependence of slope is very slight. In this last
case, we used the Merrit et al. (2006) analysis who compared N-body density
profiles with various parametric models finding systematic variation in profile
shape with halo mass. This last analysis suggests that the galaxy-sized halos
obtained with our model have a different shape parameter, i.e. a different mass
distribution, than the cluster-sized halos, obtained with the same model. The
results of the present paper argue against universality of density profiles
constituted by dark matter and baryons and confirm claims of a systematic
variation in profile shape with halo mass, for dark matter halos.Comment: 11 pages, 5 figure
Improved Kidney Stone Recognition Through Attention and Multi-View Feature Fusion Strategies
This contribution presents a deep learning method for the extraction and
fusion of information relating to kidney stone fragments acquired from
different viewpoints of the endoscope. Surface and section fragment images are
jointly used during the training of the classifier to improve the
discrimination power of the features by adding attention layers at the end of
each convolutional block. This approach is specifically designed to mimic the
morpho-constitutional analysis performed in ex-vivo by biologists to visually
identify kidney stones by inspecting both views. The addition of attention
mechanisms to the backbone improved the results of single view extraction
backbones by 4% on average. Moreover, in comparison to the state-of-the-art,
the fusion of the deep features improved the overall results up to 11% in terms
of kidney stone classification accuracy.Comment: This work has been submitted to the IEEE for possible publication.
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The sizes of mini-voids in the local universe: an argument in favor of a warm dark matter model?
Using high-resolution simulations within the Cold and Warm Dark Matter models
we study the evolution of small scale structure in the Local Volume, a sphere
of 8 Mpc radius around the Local Group. We compare the observed spectrum of
mini-voids in the Local Volume with the spectrum of mini-voids determined from
the simulations. We show that the \LWDM model can easily explain both the
observed spectrum of mini-voids and the presence of low-mass galaxies observed
in the Local Volume, provided that all haloes with circular velocities greater
than 20 km/s host galaxies. On the contrary within the LCDM model the
distribution of the simulated mini-voids reflects the observed one if haloes
with maximal circular velocities larger than 35 km/s host galaxies. This
assumption is in contradiction with observations of galaxies with circular
velocities as low as 20 km/s in our Local Universe. A potential problem of the
LWDM model could be the late formation of the haloes in which the gas can be
efficiently photo-evaporated. Thus star formation is suppressed and low-mass
haloes might not host any galaxy at all.Comment: 13 pages, 10 figures, version 2, subsection 3.1 added, accepted to
MNRA
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A SNP-based consensus genetic map for synteny-based trait targeting in faba bean (Vicia faba L.)
Faba bean (Vicia faba L.) is a globally important nitrogen-fixing legume, which is widely grown in a diverse range of environments. In this work, we mine and validate a set of 845 SNPs from the aligned transcriptomes of two contrasting inbred lines. Each V. faba SNP is assigned by BLAST analysis to a single Medicago orthologue. This set of syntenically anchored polymorphisms were then validated as individual KASP assays, classified according to their informativeness and performance on a panel of 37 inbred lines, and the best performing 757 markers used to genotype six mapping populations. The six resulting linkage maps were merged into a single consensus map on which 687 SNPs were placed on six linkage groups, each presumed to correspond to one of the six V. faba chromosomes. This sequence-based consensus map was used to explore synteny with the most closely related crop species, lentil and the most closely related fully sequenced genome, Medicago. Large tracts of uninterrupted colinearity were found between faba bean and Medicago, making it relatively straightforward to predict gene content and order in mapped genetic interval. As a demonstration of this, we mapped a flower colour gene to a 2-cM interval of Vf chromosome 2 which was highly colinear with Mt3. The obvious candidate gene from 78 gene models in the collinear Medicago chromosome segment was the previously characterized MtWD40-1 gene controlling anthocyanin production in Medicago and resequencing of the Vf orthologue showed a putative causative deletion of the entire 50 end of the gene.Peer reviewe
Dark Matter Subhalos in the Ursa Minor Dwarf Galaxy
Through numerical simulations, we study the dissolution timescale of the Ursa
Minor cold stellar clump, due to the combination of phase-mixing and
gravitational encounters with compact dark substructures in the halo of Ursa
Minor. We compare two scenarios; one where the dark halo is made up by a smooth
mass distribution of light particles and one where the halo contains 10% of its
mass in the form of substructures (subhalos). In a smooth halo, the stellar
clump survives for a Hubble time provided that the dark matter halo has a big
core. In contrast, when the point-mass dark substructures are added, the clump
survives barely for \sim 1.5 Gyr. These results suggest a strong test to the
\Lambda-cold dark matter scenario at dwarf galaxy scale.Comment: accepted for publication in Ap
On the physical origin of dark matter density profiles
The radial mass distribution of dark matter haloes is investigated within the
framework of the spherical infall model. We present a new formulation of
spherical collapse including non-radial motions, and compare the analytical
profiles with a set of high-resolution N-body simulations ranging from galactic
to cluster scales. We argue that the dark matter density profile is entirely
determined by the initial conditions, which are described by only two
parameters: the height of the primordial peak and the smoothing scale. These
are physically meaningful quantities in our model, related to the mass and
formation time of the halo. Angular momentum is dominated by velocity
dispersion, and it is responsible for the shape of the density profile near the
centre. The phase-space density of our simulated haloes is well described by a
power-law profile, rho/sigma^3 = 10^{1.46\pm0.04} (rho_c/Vvir^3)
(r/Rvir)^{-1.90\pm0.05}. Setting the eccentricity of particle orbits according
to the numerical results, our model is able to reproduce the mass distribution
of individual haloes.Comment: 12 pages, 13 figures, submitted to MNRA
Galactic halo cusp-core: tidal compression in mergers
We explain in simple terms how the buildup of dark haloes by merging compact
satellites, as in the CDM cosmology, inevitably leads to an inner cusp of
density profile with \alpha \gsim 1, as seen in
cosmological N-body simulations. A flatter halo core with exerts on
the satellites tidal compression in all directions, which prevents deposit of
stripped satellite material in the core region. This makes the satellite orbits
decay from the radius where to the halo centre with no local
tidal mass transfer and thus causes a rapid steepening of the inner profile to
. These tidal effects, the resultant steepening of the profile to a
cusp, and the stability of this cusp to tandem mergers with compact satellites,
are demonstrated using N-body simulations. The transition at is
then addressed using toy models in the limiting cases of impulse and adiabatic
approximations and using tidal radii for satellites on radial and circular
orbits. In an associated paper we address the subsequent slow convergence from
either side to an asymptotic stable cusp with \alpha \gsim 1. Our analysis
thus implies that an inner cusp is enforced when small haloes are typically
more compact than larger haloes, as in the CDM scenario, such that enough
satellite material makes it intact into the inner halo and is deposited there.
We conclude that a necessary condition for maintaining a flat core, as
indicated by observations, is that the inner regions of the CDM satellite
haloes be puffed up by about 50% such that when they merge into a bigger halo
they would be disrupted outside the halo core. This puffing up could be due to
baryonic feedback processes in small haloes, which may be stimulated by the
tidal compression in the halo cores.Comment: 19 pages, Latex, mn2e.cls, some revisions, MNRAS in pres
Density profiles of dark matter haloes on Galactic and Cluster scales
In the present paper, we improve the "Extended Secondary Infall Model" (ESIM)
of Williams et al. (2004) to obtain further insights on the cusp/core problem.
The model takes into account the effect of ordered and random angular momentum,
dynamical friction and baryon adiabatic contraction in order to obtain a
secondary infall model more close to the collapse reality. The model is applied
to structures on galactic scales (normal and dwarf spiral galaxies) and on
cluster of galaxies scales. The results obtained suggest that angular momentum
and dynamical friction are able, on galactic scales, to overcome the competing
effect of adiabatic contraction eliminating the cusp. The NFW profile can be
reobtained, in our model only if the system is constituted just by dark matter
and the magnitude of angular momentum and dynamical friction are reduced with
respect to the values predicted by the model itself. The rotation curves of
four LSB galaxies from de Blok & Bosma (2002) are compared to the rotation
curves obtained by the model in the present paper obtaining a good fit to the
observational data. On scales smaller than
the slope and on cluster scales we observe a similar
evolution of the dark matter density profile but in this case the density
profile slope flattens to for a cluster of . The total mass profile, differently from that of dark
matter, shows a central cusp well fitted by a NFW model.Comment: 26 pages; 4 figures A&A Accepte
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