2,075 research outputs found
Lowest order Virtual Element approximation of magnetostatic problems
We give here a simplified presentation of the lowest order Serendipity
Virtual Element method, and show its use for the numerical solution of linear
magneto-static problems in three dimensions. The method can be applied to very
general decompositions of the computational domain (as is natural for Virtual
Element Methods) and uses as unknowns the (constant) tangential component of
the magnetic field on each edge, and the vertex values of the
Lagrange multiplier (used to enforce the solenoidality of the magnetic
induction ). In this respect the method can be seen
as the natural generalization of the lowest order Edge Finite Element Method
(the so-called "first kind N\'ed\'elec" elements) to polyhedra of almost
arbitrary shape, and as we show on some numerical examples it exhibits very
good accuracy (for being a lowest order element) and excellent robustness with
respect to distortions
Regulação da produção da eritropoietina e perspectivas terapêuticas na anemia
About 30 years ago, the treatment of chronic renal disease anaemia was revolutionized by the introduction of recombinant human erythropoietin, which reduced the need for blood transfusions. In spite of this huge advance, the first recombinant human erythropoietin has a relatively short half-life and needs to be administered two to three times per week. Subsequently, other molecules were developed, such as darbepoetin alfa, continuous erythropoietin receptor activator (CERA) and peginesatide, with longer half-life, but the route of administration still remains a problem. Erythropoietin has an action that exceeds erythropoiesis and plays an important role in cell protection. Based on knowledge of the molecular mechanisms that control erythropoiesis, namely the regulation of EPO gene expression, through HIF system, GATA-2 and NF-kB, several upcoming therapeutic agents and strategies for stimulating and treating anaemia emerged.
The main effort in developing these treatments is to achieve other routes of administration, more convenient for the patient, such as oral therapy, not disregarding an easier production, storage and frequency of administration. Some of them are still in laboratory phase and others already in clinical trials phase II or III. In this work, based on a literature search of studies using MEDLINE, our objective is to review the regulation of erythropoietin production and its functions, as well as treatment approach for anaemia of chronic kidney disease, with particular focus on new therapiesHá cerca de 30 anos atrás, o tratamento da anemia da doença renal crónica foi revolucionado pela introdução da eritropoietina (EPO) humana recombinante que permitiu reduzir drasticamente a necessidade de transfusões sanguÃneas. Apesar deste grande avanço, a primeira EPO humana recombinante tem uma semivida relativamente curta e tem de ser administrada duas a três vezes por semana. Subsequentemente, foram desenvolvidas outras moléculas, como a darbepoetina alfa, o ativador contÃnuo do EPO-R (CERA) e o peginesatide, com uma semivida mais longa, mas a via de administração continua a ser exclusivamente parenteral. A eritropoietina desempenha várias funções além da eritropoiética. Tendo por base os mecanismos moleculares que controlam a eritropoiese, nomeadamente a regulação da expressão do gene da EPO, através do sistema do HIF, GATA-2 e NF-kB, surgiram vários fármacos e estratégias terapêuticas para o tratamento da anemia. O principal objetivo destes novos tratamentos passa por desenvolver outras vias de administração, mais cómodas para o doente, como a terapia oral, e facilitar a produção, armazenamento e frequência de administração dos fármacos. Alguns destes ainda se encontram em fase laboratorial, enquanto outros já estão em ensaios clÃnicos fase II ou III. Neste trabalho, baseado na revisão bibliográfica de artigos cientÃficos publicados na MEDLINE, procuramos rever a regulação da produção da EPO e respetivas funções, bem como abordar o tratamento da anemia da doença renal crónica, com especial enfoque nas novas terapêutica
SUPG-stabilized Virtual Elements for diffusion-convection problems: a robustness analysis
The objective of this contribution is to develop a convergence analysis for
SUPG-stabilized Virtual Element Methods in diffusion-convection problems that
is robust also in the convection dominated regime. For the original method
introduced in [Benedetto et al, CMAME 2016] we are able to show an "almost
uniform" error bound (in the sense that the unique term that depends in an
unfavorable way on the parameters is damped by a higher order mesh-size
multiplicative factor). We also introduce a novel discretization of the
convection term that allows us to develop error estimates that are fully robust
in the convection dominated cases. We finally present some numerical result
A family of three-dimensional virtual elements with applications to magnetostatic
We consider, as a simple model problem, the application of Virtual Element
Methods (VEM) to the linear Magnetostatic three-dimensional problem in the
formulation of F. Kikuchi. In doing so, we also introduce new serendipity VEM
spaces, where the serendipity reduction is made only on the faces of a general
polyhedral decomposition (assuming that internal degrees of freedom could be
more easily eliminated by static condensation). These new spaces are meant,
more generally, for the combined approximation of -conforming (-forms),
-conforming (-forms), and -conforming
(-forms) functional spaces in three dimensions, and they would surely be
useful for other problems and in more general contexts.Comment: Submitted to SINU
Spatially Resolved Spitzer-IRS Spectral Maps of the Superwind in M82
We have mapped the superwind/halo region of the nearby starburst galaxy M82
in the mid-infrared with . The spectral regions covered include
the H, [NeII], [NeIII] emission lines and PAH features. We
estimate the total warm H mass and the kinetic energy of the outflowing
warm molecular gas to be between M and
erg. Using the ratios of the 6.2, 7.7 and 11.3
micron PAH features in the IRS spectra, we are able to estimate the average
size and ionization state of the small grains in the superwind. There are large
variations in the PAH flux ratios throughout the outflow. The 11.3/7.7 and the
6.2/7.7 PAH ratios both vary by more than a factor of five across the wind
region. The Northern part of the wind has a significant population of PAH's
with smaller 6.2/7.7 ratios than either the starburst disk or the Southern
wind, indicating that on average, PAH emitters are larger and more ionized. The
warm molecular gas to PAH flux ratios (H) are enhanced in the outflow
by factors of 10-100 as compared to the starburst disk. This enhancement in the
H ratio does not seem to follow the ionization of the atomic gas (as
measured with the [NeIII]/[NeII] line flux ratio) in the outflow. This suggests
that much of the warm H in the outflow is excited by shocks. The observed
H line intensities can be reproduced with low velocity shocks ( km
s) driven into moderately dense molecular gas (
cm) entrained in the outflow.Comment: 19 pages and 12 figures; accepted in MNRA
Urinary Biomarkers for Kidney Disease in ATTR Amyloidosis
Aim: The detection and prognosis of nephropathy in transthyretin amyloidosis depends on albuminuria and renal function. Knowing that urinary levels of alpha-1 microglobulin and beta-2 microglobulin reflect tubular dysfunction while urinary alpha-2 macroglobulin implies glomerular damage, we decide investigate the diagnostic value of these markers in the patients with transthyretin amyloidosis.
Methods: Serum and urinary samples collected from 30 patients and 11 asymptomatic carriers were tested for alpha-1 microglobulin, beta-2 microglobulin, alpha-2 macroglobulin, albumin, creatinine and cystatin C.
Results: Pathological urinary alpha-1 microglobulin was detected in 17 patients, beta-2 microglobulin in 6 and alpha-2 macroglobulin in 5; 5 patients had albuminuria (mg/g creatinine) 30-300 and in 20 patients values >300 were present. Asymptomatic carriers did not present pathological excretion of these biomarkers and albuminuria was >30 in 1 individual. The excretion rates of alpha-1 microglobulin and beta-2 microglobulin were positively correlated with albuminuria (P<0.001), serum creatinine (P<0.05) and cystatin C (P<0.001). Urinary alpha-2 macroglobulin was almost exclusively found in the presence of albuminuria, although their levels do not correlate.
Conclusion: Urinary biomarkers emerge as a potential approach to detect renal disease but unexpectedly, urinary alpha-2 macroglobulin was not a marker of the severity of albuminuria
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