81 research outputs found
No-splitting property and boundaries of random groups
We prove that random groups in the Gromov density model, at any density,
satisfy property (FA), i.e. they do not act non-trivially on trees. This
implies that their Gromov boundaries, defined at density less than 1/2, are
Menger curves.Comment: 20 page
Compactifications and algebraic completions of Limit groups
In this paper we consider the existence of dense embeddings of Limit groups
in locally compact groups generalizing earlier work of Breuillard, Gelander,
Souto and Storm [GBSS] where surface groups were considered. Our main results
are proved in the context of compact groups and algebraic groups over local
fields. In addition we prove a generalization of the classical Baumslag lemma
which is a useful tool for generating eventually faithful sequences of
homomorphisms. The last section is dedicated to correct a mistake from [BGSS]
and to get rid of the even genus assumption.Comment: v2: Substantial changes to sections 7 and 8.2. Typos corrected.
References added. v3: Acknowledgement correcte
Role of urothelial cells in BCG immunotherapy for superficial bladder cancer
Intravesical instillation of Bacillus Calmette-GuΓ©rin (BCG) is used for the treatment of superficial bladder cancer, both to reduce the recurrence rate of bladder tumour and to diminish the risk of progression. Since its first therapeutic application in 1976, major research efforts have been directed to decipher the exact mechanism of action of the BCG-associated antitumour effect. Bacillus Calmette-GuΓ©rin causes an extensive local inflammatory reaction in the bladder wall. Of this, the massive appearance of cytokines in the urine of BCG-treated patients stands out. Activated lymphocytes and macrophages are the most likely sources of these cytokines, but at present other cellular sources such as urothelial tumour cells cannot be ruled out. Bacillus Calmette-GuΓ©rin is internalised and processed both by professional antigen-presenting cells and urothelial tumour cells, resulting in an altered gene expression of these cells that accumulates in the presentation of BCG antigens and secretion of particular cytokine
Anosov representations: Domains of discontinuity and applications
The notion of Anosov representations has been introduced by Labourie in his
study of the Hitchin component for SL(n,R). Subsequently, Anosov
representations have been studied mainly for surface groups, in particular in
the context of higher Teichmueller spaces, and for lattices in SO(1,n). In this
article we extend the notion of Anosov representations to representations of
arbitrary word hyperbolic groups and start the systematic study of their
geometric properties. In particular, given an Anosov representation of
into G we explicitly construct open subsets of compact G-spaces, on which
acts properly discontinuously and with compact quotient.
As a consequence we show that higher Teichmueller spaces parametrize locally
homogeneous geometric structures on compact manifolds. We also obtain
applications regarding (non-standard) compact Clifford-Klein forms and
compactifications of locally symmetric spaces of infinite volume.Comment: 63 pages, accepted for publication in Inventiones Mathematica
Prevalence and risk factors of helminths and intestinal protozoa infections among children from primary schools in western Tajikistan
BACKGROUND: Intestinal parasitic infections represent a public health problem in Tajikistan, but epidemiological evidence is scarce. The present study aimed at assessing the extent of helminths and intestinal protozoa infections among children of 10 schools in four districts of Tajikistan, and to make recommendations for control.
METHODS: A cross-sectional survey was carried out in early 2009. All children attending grades 2 and 3 (aged 7-11 years) from 10 randomly selected schools were invited to provide a stool sample and interviewed about sanitary situation and hygiene behaviour. A questionnaire pertaining to demographic and socioeconomic characteristics was addressed to the heads of households. On the spot, stool samples were subjected to duplicate Kato-Katz thick smear examination for helminth diagnosis. Additionally, 1-2 g of stool was fixed in sodium acetate-acetic acid formalin, transferred to a specialized laboratory in Europe and examined for helminths and intestinal protozoa. The results from both methods combined served as diagnostic 'gold' standard.
RESULTS: Out of 623 registered children, 602 participated in our survey. The overall prevalence of infection with helminths and pathogenic intestinal protozoa was 32.0% and 47.1%, respectively. There was pronounced spatial heterogeneity. The most common helminth species was Hymenolepis nana (25.8%), whereas the prevalences of Ascaris lumbricoides, hookworm and Enterobius vermicularis were below 5%. The prevalence of pathogenic intestinal protozoa, namely Giardia intestinalis and Entamoeba histolytica/E. dispar was 26.4% and 25.9%, respectively. Almost half of the households draw drinking water from unimproved sources, such as irrigation canals, rivers and unprotected wells. Sanitary facilities were pit latrines, mostly private, and a few shared with neighbours. The use of public tap/standpipe as a source of drinking water emerged as a protective factor for G. intestinalis infection. Protecte spring water reduced the risk of infection with E. histolytica/E. dispar and H. nana.
CONCLUSIONS: Our data obtained from the ecological 'lowland' areas in western Tajikistan call for school-based deworming (recommended drugs: albendazole and metronidazole), combined with hygiene promotion and improved sanitation. Further investigations are needed to determine whether H. nana represents a public health problem
Insect Pollinated Crops, Insect Pollinators and US Agriculture: Trend Analysis of Aggregate Data for the Period 1992β2009
In the US, the cultivated area (hectares) and production (tonnes) of crops that require or benefit from insect pollination (directly dependent crops: apples, almonds, blueberries, cucurbits, etc.) increased from 1992, the first year in this study, through 1999 and continued near those levels through 2009; aggregate yield (tonnes/hectare) remained unchanged. The value of directly dependent crops attributed to all insect pollination (2009 USD) decreased from 10.69 billion in 2001, but increased thereafter, reaching 11.68 billion and 15.45 billion in 1996 to 5.39 billion and 4.99 and $7.04 billion. Trend analysis demonstrates that US producers have a continued and significant need for insect pollinators and that a diminution in managed or wild pollinator populations could seriously threaten the continued production of insect pollinated crops and crops grown from seeds resulting from insect pollination
Gene expression profile of mouse fibroblasts exposed to a biodegradable iron alloy for stents.
Iron-based materials could constitute an interesting option for cardiovascular biodegradable stent applications due to their superior ductility compared to their counterparts - magnesium alloys. Since the predicted degradation rate of pure iron is considered slow, manganese (35% w/w), an alloying element for iron, was explored to counteract this problem through the powder metallurgy process (Fe-35 Mn). However, manganese presents a high cytotoxic potential; thus its effect on cells must first be established. Here, we established the gene expression profile of mouse 3T3 fibroblasts exposed to Fe-35 Mn degradation products in order to better understand cell response to potentially cytotoxic degradable metallic material (DMM). Mouse 3T3 cells were exposed to degradation products eluting through tissue culture insert filter (3 ΞΌm pore size) containing cytostatic amounts of 3.25 mg ml(-1) of Fe-35 Mn powder, 0.25 mg ml(-1) of pure Mn powder or 5 mg ml(-1) of pure iron powder for 24 h. We then conducted a gene expression profiling study from these cells. Exposure of 3T3 cells to Fe-35 Mn was associated with the up-regulation of 75 genes and down-regulation of 59 genes, while 126 were up-regulated and 76 down-regulated genes in the presence of manganese. No genes were found regulated for the iron powder. When comparing the GEP of 3T3 fibroblasts in the presence of Fe-35 Mn and Mn, 68 up-regulated and 54 down-regulated genes were common. These results were confirmed by quantitative RT-PCR for a subset of these genes. This GEP study could provide clues about the mechanism behind degradation products effects on cells of the Fe-35 Mn alloy and may help in the appraisal of its potential for DMM applications
Attitude measurement transfer systems study Final report
European Space Agency contract reportAvailable from British Library Document Supply Centre- DSC:3425.929(ESA-CR(P)--3949(v.1)) / BLDSC - British Library Document Supply CentreSIGLEGBUnited Kingdo
Attitude measurement transfer systems study Executive summary
European Space Agency contract reportAvailable from British Library Document Supply Centre- DSC:3425.929(ESA-CR(P)--3949(v.2)) / BLDSC - British Library Document Supply CentreSIGLEGBUnited Kingdo
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