248 research outputs found
Free cyclic actions on surfaces and the Borsuk-Ulam theorem
Let and be topological spaces, let be a group, and let be a proper free action of . In this
paper, we define a Borsuk-Ulam-type property for homotopy classes of maps from
to with respect to the pair that generalises the classical
antipodal Borsuk-Ulam theorem of maps from the -sphere to
. In the cases where is a finite pathwise-connected
CW-complex, is a finite, non-trivial Abelian group, is a proper free
cellular action, and is either or a compact surface without
boundary different of and , we give an algebraic
criterion involving braid groups to decide whether a free homotopy class has the Borsuk-Ulam property. As an application of this criterion,
we consider the case where is a compact surface without boundary equipped
with a free action of the finite cyclic group . In terms
of the orientability of the orbit space of by the action ,
the value of modulo and a certain algebraic condition involving the
first homology group of , we are able to determine if the single
homotopy class of maps from to possesses the Borsuk-Ulam
property with respect to . Finally, we give some examples
of surfaces on which the symmetric group acts, and for these cases, we obtain
some partial results regarding the Borsuk-Ulam property for maps whose target
is .Comment: 18 pages, 2 figure
The Borsuk-Ulam property for homotopy classes on bundles, parametrized braids groups and applications for surfaces bundles
Let and be fiber bundles over the same base , where is endowed
with a free involution over . A homotopy class
(over ) is said to have the Borsuk-Ulam property with respect to if
for every fiber-preserving map over which represents
there exists a point such that . In the
cases that is a -space and the fibers of the projections and are closed surfaces and , respectively,
we show that the problem of decide if a homotopy class of a fiber-preserving
map over has the Borsuk-Ulam property is equivalent of an
algebraic problem involving the fundamental groups of , the orbit space of
by and a type of generalized braid groups of that we call
parametrized braid groups. As an application, we determine the homotopy classes
of self fiber-preserving maps of some 2-torus bundles over that
satisfy the Borsuk-Ulam property with respect to certain involutions
over
IndustrializaciĂłn de un absorbedor modular de vibraciones
Se trata de la industrializaciĂłn de un absorbedor modular de vibraciones basado en la tecnologĂa TMD (Tuned Mass Damper) a travĂ©s de la construcciĂłn de una maqueta digital parametrizada con el objetivo de crear una gama de producto que pueda ser comercializada. La evoluciĂłn de este producto, partiendo de un prototipo inicial, presenta mejoras tecnolĂłgicas las cuales hacen que nuestro producto se diferencie de otros TMD.
Cada producto concreto se define mediante una hoja de cĂĄlculo donde obtendremos como salida los valores de los parĂĄmetros del modelo TMD de CATIA, en funciĂłn de los datos de entrada que nos ofrece el cliente. La hoja de cĂĄlculo fue construida empleando una hoja EXCEL donde presentamos todas las ecuaciones que rigen el TMD.
Finalmente, se presentarĂĄ el prototipo de TMD construido en el laboratorio de estructuras, el cual fue empleado para testar las nuevas soluciones tecnolĂłgicas implementadas en la maqueta digital ofrecida a los clientes.It is about the industrialization of a modular absorber of vibrations using the TMDâs technologies (Tuned Mass Damper) through the construction of a parametric digital mock-up with the goal of creating a range of this product that could be marketable. The evolution of this product, based on an initial prototype, provides some technological improvements which make our product different from other TMDs.
The different models of this product are based on a spreadsheet where we obtain the parameterÂŽs values of the TMD model of CATIA, depending on the input data offered by the client. The spreadsheet was developed using an EXCEL sheet where we show all TMDâs equations.
Finally, both the digital mock-up and the mockup of the prototype are presented. They were built in the laboratory of structures and the mockup of the prototype was used to test these new solutions.Departamento de Construcciones ArquitectĂłnicas, IngenierĂa del Terreno y MecĂĄnica de los Medios Continuos y TeorĂa de EstructurasMĂĄster en IngenierĂa Industria
First evidence of borings in calamitean stems and other plant-arthropod interactions from the late Pennsylvanian of the Saale Basin
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The probiotic Escherichia coli strain Nissle 1917 (EcN) stops acute diarrhoea in infants and toddlers
In most cases, acute diarrhoea will become self-limiting during the first few days after onset. For young children, however, health risks may develop when the disease lasts longer than 3 days. The purpose of the present trial was to determine whether the stool frequency of infants and toddlers suffering from acute diarrhoea could be normalised more quickly by administering the probiotic Escherichia coli Nissle 1917 (EcN) solution than by administering a placebo. The safety of EcN were also assessed. A total of 113 children (aged 2â47 months) with acute diarrhoea (> three watery or loose stools in 24 h) were randomised to either a group receiving the probiotic EcN suspension (nâ=â55) or a group receiving the placebo suspension (nâ=â58) in a confirmative, double-blind clinical trial. Depending on the age of patients, 1â3 ml per day of verum suspension (10(8) viable EcN cells per millilitre) or placebo were administered orally. The causes of the diarrhoea were viral rather than bacterial, but they were mainly unspecific infections. The median onset of treatment response (reduction of daily stool frequency to †three watery or loose stools over at least 2 consecutive days) occurred more rapidly in the children receiving the EcN solution (2.5 days) than in those receiving the placebo (4.8 days), a significant difference (2.3 days; pâ=â0.0007). The number of patients showing a response was clearly higher (pâ<â0.0001) in the EcN group (52/55; 94.5%) than in the placebo group (39/58; 67.2%). EcN was found to be safe and well-tolerated, and it showed a significant superiority compared to the placebo in the treatment of acute diarrhoea in infants and toddlers. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:http://dx.doi.org/10.1007/s00431-007-0419-x) contains supplementary material, which is available to authorized users
Identification of chitinase-3-like protein 1 as a novel neutrophil antigenic target in Crohnâs disease
Background and Aims
There is an increasing incidence of inflammatory bowel disease [IBD]. Autoimmune responses are involved in the pathophysiology of IBD, but their underlying pathways and target antigens have not yet been fully elucidated.
Methods
Autoantigenic targets in IBD were identified after separation of whole cell proteins isolated from neutrophils using two-dimensional electrophoresis and matrix assisted laser desorption ionization â time of flight mass spectrometry-based protein identification of the spots that displayed Western blotting signals with anti-neutrophil cytoplasmic antibody-positive sera. The prevalence of IgG, IgA and secretory IgA [sIgA] to chitinase 3-like protein 1 [CHI3L1] was analysed by enzyme-linked immunosorbent assays using recombinant CHI3L1 in 110 patients with Crohnâs disease [CD], 95 with ulcerative colitis [UC], 126 with coeliac disease [CeD] and 86 healthy controls [HCs].
Results
The 18-glycosylhydrolase family member CHI3L1 was identified as a neutrophil autoantigenic target. CD patients displayed significantly higher levels of IgG to CHI3L1 than patients with UC and CeD (p < 0.0001, respectively). IgA and sIgA to CHI3L1 was significantly higher in CD than in UC, CeD and HCs [p < 0.0001, respectively]. IgA and sIgA to CHI3L1 demonstrated the highest prevalence in CD [25.5%, 28/110; and 41.8%%, 46/110] compared to HCs [2.3%, 2/86; and 4.7%%, 4/86; p = 0.0015 and p < 0.0001] and are associated with a more complicated progression of CD.
Conclusion
CHI3L1 is a novel neutrophil autoantigenic target in CD. IgA and sIgA to CHI3L1 may serve as novel markers for CD and may facilitate the serological diagnosis of IBD
PR3-ANCAs Detected by Third-Generation ELISA Predicts Severe Disease and Poor Survival in Primary Sclerosing Cholangitis
A highly sensitive detection of anti-neutrophil cytoplasmic antibodies to serine
proteinase-3 (PR3-ANCAs) aids in the serological diagnosis of autoimmune liver disorders and the
prediction of severity in primary sclerosing cholangitis (PSC). Here, we evaluate a novel thirdgeneration ELISA for the detection of PR3-ANCAs. In total, 309 patients with PSC, 51 with primary
biliary cholangitis (PBC), and 120 healthy blood donors (BD) were analyzed. For the survival
analysis in PSC, the outcome was defined as liver-transplantation-free survival during the followup. Positive PR3-ANCA levels were found in 74/309 (24.0%) of patients with PSC. No BDs and one
patient with PBC demonstrated PR3-ANCA positivity. PR3-ANCAs were revealed as independent
predictors for a poor PSC outcome (study endpoint: liver transplantation/death, log-rank test, p =
0.02). PR3-ANCA positivity, lower albumin levels, and higher bilirubin concentrations were
independent risks of a poor survival (Cox proportional-hazards regression analysis, p < 0.05). The
Mayo risk score for PSC was associated with PR3-ANCA positivity (p = 0.01) and the disease
severity assessed with a model of end-stage liver disease (MELD) and extended MELD-Na (p < 0.05).
PR3-ANCAs detected by a third-generation ELISA are diagnostic and prognostic markers for PSC.
Their wider use could help to identify patients who are at-risk of a more severe disease
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