83 research outputs found
Geometric Hermite interpolation by rational curves of constant width
A constructive characterization of the support function for a rationally parameterized curve of constant width is given. In addition, a Hermite interpolation problem for such kind of curves is solved, which yields a method to determine a rational curve of constant width that passes through a set of free points with the corresponding tangent directions. Finally, the case of piecewise rational support functions is considered, which increases the design freedom. The procedure is presented in the general case of hedgehogs of constant width taking the advantage of projective hedgehogs, so that some constraints must be taken to ensure convexity of the desired curve.Funding for the other authors not affiliated with BCAM:
Grant PID2021-124577NBI00 funded by MCIN/AEI/10.13039/501100011033 and by “ERDF A way of making Europe”.
Project PID2019-104927GB-C21 funded by MCIN/AEI/10.13039/501100011033.
Project UJI-B2022-19 funded by Universitat Jaume I.
Project CIAICO/2021/180 funded by Generalitat Valenciana
Efectos del abandono de las políticas públicas de vivienda en barrios populares y multiculturales
Los barrios periféricos del desarrollismo franquista atraviesan procesos de diversificación y precarización similares, acogiendo hoy a una población multicultural y con posiciones de clase po-pulares. El estudio cuantitativo de los cambios sociodemográficos en dos barrios de Zaragoza y Madrid es complementado, mediante una aproximación cualitativa, con el análisis de las estrategias vecina-les, tanto colectivas como individuales. Estas se despliegan, con mayor o menor éxito, ante la ausencia de unas políticas públicas de vivienda que frenen el deterioro urbanístico y social de estos territorios. Concluimos que los contextos políticos locales, tanto institucionales como asociativos, propician diferentes ritmos en la evolución de la precarización de la vivienda y sus habitantes. En ambos casos, estas fases convergen en escenarios de reperiferización. The peripheral neighborhoods of Francoist “desarrollismo” period are going through similar diversification and precarization processes. Nowadays, they are the place of residence of a multicultural population with popular class positions. The quantitative study of the sociodemographic changes in two neighborhoods of Zaragoza and Madrid is complemented, through a qualitative approach, with the analysis of neighborhood strategies, both collective and individual. These strategies are deployed with diverse success, and in the absence of public housing policies that could stop the urban and social deterioration of these territories. We conclude that local political contexts, both institutional and associative, foster different rhythms in the evolution of the precariousness of housing and its inhabitants. In both cases, these stages converge in scenarios of re-peripheralization
A survey of partial differential equations in geometric design
YesComputer aided geometric design is an area
where the improvement of surface generation techniques
is an everlasting demand since faster and more accurate
geometric models are required. Traditional methods
for generating surfaces were initially mainly based
upon interpolation algorithms. Recently, partial differential
equations (PDE) were introduced as a valuable
tool for geometric modelling since they offer a number
of features from which these areas can benefit. This work
summarises the uses given to PDE surfaces as a surface
generation technique togethe
Prilog istraživanju promjena na škrgama zebrice (Danio rerio) prilikom izloženosti dioksinu
This study determined cell changes in the gills of zebrafish (Danio rerio, Hamilton, 1822) as a result of a dietary supply of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). 50 zebrafish were divided into five groups, one control group and four experimental ones. The experimental groups were supplied 10, 40, 100 and 270 ng/day/fish TCDD, respectively. Structural, ultrastructural and
morphometric studies of the fish gill were carried out, indicating that, in low concentrations, fish gills presented hyperemia with progressive erosion of the endothelium of the capillaries resulting in
edema and microhaemorrhages. In the non-respiratory gill, in those groups with low concentrations, it could be observed that the chloride cells presented hypertrophy as a result of dilatation of the intracellular canal and swelling of the microvilli, losing their activity in the degradation of chemical substances (according to some authors) in those groups with a higher concentration. Mucous cells
presented hyperplasia and hypertrophy. The sensory buds were not directly affected, but, due to the presence of interstitial edema, swelling of the supporting cells occurred without the involvement of the neurosensory cells. We concluded that dioxins affect the gills to a greater or lesser extent
depending on their concentration in the fish’s diet, which alters their functionality.Ovim istraživanjem utvrđene su promjene na stanicama škrga zebrice (Danio rerio, Hamilton, 1822) kao rezultat hranjena 2,3,7,8 tetraklorodibenzo p-dioksinom (TCDD). Pedeset jedinki zebrice
podijeljeno je u pet grupa, jednu kontrolnu grupu i četiri eksperimentalne. Eksperimentalnim grupama davano je 10, 40, 100 i 270 ng/riba/dan TCDD. Provedena su strukturalna, ultrastrukturalna i morfološka istraživanja škrga ribe, ukazujući da su škrge riba pokazivale hiperemiju s progresivnom
erozijom endotel kapilara koja je rezultirala edemima i mikrokrvarenjima. Kod grupa kojima je dana manja koncentracija, u škrgama koje ne služe za disanje može se primijetiti da kloridne stanice pokazuju hipertrofiju kao posljedicu dilatacije međustaničnog kanala i oticanje mikroresica kojima se smanjuje aktivnost tijekom razgradnje kemijskih tvari (prema mišljenjima nekih autora) u onim grupama koje su bile izložene većim koncentracijama. Mukozne stanice pokazuju hiperplaziju i
hipertrofiju. Osjetni pupoljci nisu bili izravno pogođeni, ali, zbog prisutnosti intersticijskog edema, oticanja potpornih stanica bez uključivanja neurosenzornih stanica. Zaključak je da dioksini utječu
na škrge u većoj ili manjoj mjeri ovisno o njihovoj koncentraciji u ishrani ribe, što mijenja njihovu funkcionalnost
On the computation of zone and double zone diagrams
Classical objects in computational geometry are defined by explicit
relations. Several years ago the pioneering works of T. Asano, J. Matousek and
T. Tokuyama introduced "implicit computational geometry", in which the
geometric objects are defined by implicit relations involving sets. An
important member in this family is called "a zone diagram". The implicit nature
of zone diagrams implies, as already observed in the original works, that their
computation is a challenging task. In a continuous setting this task has been
addressed (briefly) only by these authors in the Euclidean plane with point
sites. We discuss the possibility to compute zone diagrams in a wide class of
spaces and also shed new light on their computation in the original setting.
The class of spaces, which is introduced here, includes, in particular,
Euclidean spheres and finite dimensional strictly convex normed spaces. Sites
of a general form are allowed and it is shown that a generalization of the
iterative method suggested by Asano, Matousek and Tokuyama converges to a
double zone diagram, another implicit geometric object whose existence is known
in general. Occasionally a zone diagram can be obtained from this procedure.
The actual (approximate) computation of the iterations is based on a simple
algorithm which enables the approximate computation of Voronoi diagrams in a
general setting. Our analysis also yields a few byproducts of independent
interest, such as certain topological properties of Voronoi cells (e.g., that
in the considered setting their boundaries cannot be "fat").Comment: Very slight improvements (mainly correction of a few typos); add DOI;
Ref [51] points to a freely available computer application which implements
the algorithms; to appear in Discrete & Computational Geometry (available
online
Modular classes of skew algebroid relations
Skew algebroid is a natural generalization of the concept of Lie algebroid.
In this paper, for a skew algebroid E, its modular class mod(E) is defined in
the classical as well as in the supergeometric formulation. It is proved that
there is a homogeneous nowhere-vanishing 1-density on E* which is invariant
with respect to all Hamiltonian vector fields if and only if E is modular, i.e.
mod(E)=0. Further, relative modular class of a subalgebroid is introduced and
studied together with its application to holonomy, as well as modular class of
a skew algebroid relation. These notions provide, in particular, a unified
approach to the concepts of a modular class of a Lie algebroid morphism and
that of a Poisson map.Comment: 20 page
Draft Genome Sequence of Xylella fastidiosa subsp. Fastidiosa Strain IVIA5235, Isolated from Prunus avium in Mallorca Island, Spain
We report the complete annotated genome sequence of the plant-pathogenic bacterium Xylella fastidiosa subsp. fastidiosa strain IVIA5235. This strain was recovered from a cherry tree in Mallorca, Spain
SARS-CoV-2 infection induces a dual response in liver function tests: Association with mortality during hospitalization
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is associated with abnormal liver function tests. We hypothesized that early altered liver biochemistries at admission might have different clinical relevance than subsequent changes during hospitalization. A single-center retrospective study was conducted on 540 consecutive hospitalized patients, PCR-diagnosed with SARS-CoV-2. Liver test abnormalities were defined as the elevation of either gamma-glutamyltransferase (GGT), alanine aminotransferase (ALT), or aspartate aminotransferase (AST), above the upper limit of normality set by our laboratory. Linear mixed models (LMM) evaluated longitudinal associations, incorporating all available follow-up laboratory chemistries. By the end of the follow-up period, 502 patients (94.5%) were discharged (109 (20.5%) died). A total of 319 (64.3%) had at least one abnormal liver test result at admission. More prevalent were elevated AST (40.9%) and GGT (47.3%). Abnormalities were not associated with survival but with respiratory complications at admission. Conversely, LMM models adjusted for age and sex showed that longitudinal increases during hospitalization in ferritin, GGT, and alkaline phosphatase (ALP), as well as a decreased albumin levels, were associated with reduced survival. This dual pattern of liver damage might reconcile previous conflicting reports. GGT and ALP trajectories could be useful to determine who might need more surveillance and intensive care
Supercoherent States, Super K\"ahler Geometry and Geometric Quantization
Generalized coherent states provide a means of connecting square integrable
representations of a semi-simple Lie group with the symplectic geometry of some
of its homogeneous spaces. In the first part of the present work this point of
view is extended to the supersymmetric context, through the study of the
OSp(2/2) coherent states. These are explicitly constructed starting from the
known abstract typical and atypical representations of osp(2/2). Their
underlying geometries turn out to be those of supersymplectic OSp(2/2)
homogeneous spaces. Moment maps identifying the latter with coadjoint orbits of
OSp(2/2) are exhibited via Berezin's symbols. When considered within
Rothstein's general paradigm, these results lead to a natural general
definition of a super K\"ahler supermanifold, the supergeometry of which is
determined in terms of the usual geometry of holomorphic Hermitian vector
bundles over K\"ahler manifolds. In particular, the supergeometry of the above
orbits is interpreted in terms of the geometry of Einstein-Hermitian vector
bundles. In the second part, an extension of the full geometric quantization
procedure is applied to the same coadjoint orbits. Thanks to the super K\"ahler
character of the latter, this procedure leads to explicit super unitary
irreducible representations of OSp(2/2) in super Hilbert spaces of
superholomorphic sections of prequantum bundles of the Kostant type. This work
lays the foundations of a program aimed at classifying Lie supergroups'
coadjoint orbits and their associated irreducible representations, ultimately
leading to harmonic superanalysis. For this purpose a set of consistent
conventions is exhibited.Comment: 53 pages, AMS-LaTeX (or LaTeX+AMSfonts
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