5,507 research outputs found
Buckling of a growing tissue and the emergence of two-dimensional patterns
The process of biological growth and the associated generation of residual stress has previously been considered as a driving mechanism for tissue buckling and pattern selection in numerous areas of biology. Here, we develop a two-dimensional thin plate theory to simulate the growth of cultured intestinal epithelial cells on a deformable substrate, with the goal of elucidating how a tissue engineer might best recreate the regular array of invaginations (crypts of LieberkĂźhn) found in the wall of the mammalian intestine. We extend the standard von KĂĄrmĂĄn equations to incorporate inhomogeneity in the plateâs mechanical properties and surface stresses applied to the substrate by cell proliferation. We determine numerically the configurations of a homogeneous plate under uniform cell growth, and show how tethering to an underlying elastic foundation can be used to promote higher-order buckled configurations. We then examine the independent effects of localised softening of the substrate and spatial patterning of cellular growth, demonstrating that (within a two-dimensional framework, and contrary to the predictions of one-dimensional models) growth patterning constitutes a more viable mechanism for control of crypt distribution than does material inhomogeneity
A novel mass spectrometric strategy "bEMAP" reveals Extensive O-linked protein glycosylation in Enterotoxigenic Escherichia coli
Š The Author(s) 2016. The attachment of sugars to proteins via side-chain oxygen atoms (O-linked glycosylation) is seen in all three domains of life. However, a lack of widely-applicable analytical tools has restricted the study of this process, particularly in bacteria. In E. coli, only four O-linked glycoproteins have previously been characterized. Here we present a glycoproteomics technique, termed BEMAP, which is based on the beta-elimination of O-linked glycans followed by Michael-addition of a phosphonic acid derivative, and subsequent titanium dioxide enrichment. This strategy allows site-specific mass-spectrometric identification of proteins with O-linked glycan modifications in a complex biological sample. Using BEMAP we identified cell surface-associated and membrane vesicle glycoproteins from Enterotoxigenic E. coli (ETEC) and non-pathogenic E. coli K-12. We identified 618 glycosylated Serine and Threonine residues mapping to 140 proteins in ETEC, including several known virulence factors, and 34 in E. coli K-12. The two strains had 32 glycoproteins in common. Remarkably, the majority of the ETEC glycoproteins were conserved in both strains but nevertheless were only glycosylated in the pathogen. Therefore, bacterial O-linked glycosylation is much more extensive than previously thought, and is especially important to the pathogen
Will more of the same achieve malaria elimination? Results from an integrated macroeconomic epidemiological demographic model
This is the author accepted manuscript. The final version is available from the publisher via the DOI in this recordThe data underlying the model framework are available
from the authors on request and selected parameters are also tabulated in the methods paper,22 and from the Malaria Atlas Project http://
www.map.ox.ac.uk/Historic levels of funding have reduced the global burden of malaria in recent years. Questions remain,
however, as to whether scaling up interventions, in parallel with economic growth, has made malaria elimination more
likely today than previously. The consequences of âtrying but failingâ to eliminate malaria are also uncertain. Reduced
malaria exposure decreases the acquisition of semi-immunity during childhood, a necessary phase of the immunological
transition that occurs on the pathway to malaria elimination. During this transitional period, the risk of malaria resurgence
increases as proportionately more individuals across all age-groups are less able to manage infections by immune
response alone. We developed a robust model that integrates the effects of malaria transmission, demography, and
macroeconomics in the context of Plasmodium falciparum malaria within a hyperendemic environment. We analyzed the
potential for existing interventions, alongside economic development, to achieve malaria elimination. Simulation results
indicate that a 2% increase in future economic growth will increase the US7.2 billion, although increasing regional insecticide-treated net coverage rates by 25% will lower
malaria reproduction numbers by just 9%, reduce population-wide morbidity by â0.1%, and reduce prevalence from 54%
to 46% by 2034. As scaling up current malaria control tools, combined with economic growth, will be insufficient to
interrupt malaria transmission in Ghana, high levels of malaria control should be maintained and investment in research
and development should be increased to maintain the gains of the past decade and to minimize the risk of resurgence, as
transmission dropsMedical Research Council (MRC
Forskning og udvikling i økologisk Ìgproduktion
NĂŚrvĂŚrende rapport er en beskrivelse og diskussion af forskningsprojekter gennemført under FĂJO i ĂĽrene 1996-1999. I korthed vidste forskningen følgende:
OpdrĂŚtning og belĂŚgning
Det har vist sig at konventionel opdrĂŚt giver en del problemer og der er anvendt en del krĂŚfter pĂĽ at belyse konsekvensen af forskellige opdrĂŚtningsmetoder, herunder lysintensitet, adgang til udeareal, opdrĂŚt pĂĽ blivende sted eller flytning.
Konklusionen fra disse undersøgelser er, at:
Tidlig adgang til udearealet giver øget brug af udearealet senere, tendens til fÌrre gulvÌg og signifikant fÌrre snavsede Ìg
OpdrÌtning i hytte giver større kropsvÌgt, større ÌgvÌgt, fÌrre gulvÌg, fÌrre snavsede Ìg og bedre fjerdragt end opdrÌtning under konventionelle forhold.
Lav belÌgning i ÌglÌgningsperioden med 3.5 høner pr. m2 giver højere lÌggeprocent, bedre fodereffektivitet, tendens til fÌrre gulvÌg og signifikant fÌrre snavsede Ìg samt bedre fjerdragt, dog kun hos de høner, der var opdrÌttet i stald
Avl og selektion
Avlsmaterialets kvalitet har vĂŚret en vigtig del af forskningsarbejdet, dels fordi der kun er fĂĽ avlsvirksomheder tilbage, der sĂŚlger afstamninger med en vis ĂŚglĂŚgningskapacitet, dels fordi disse afstamninger primĂŚrt er fremavlet med sigte pĂĽ burĂŚgsproduktion.
Den konklusion, der kan drages af de genetiske studier er, at süfremt fjerpilningsadfÌrd inddrages i et passende selektionsprogram, vil et af de største velfÌrdsproblemer inden for Ìgproduktion blive løst.
Parasitter
Et problem, som møder den økologiske høne, er indvoldsorme. Mulighederne for at forebygge pü dette omrüde er i projektet blevet undersøgt i forskellige sammenhÌnge. Konklusionen er, at man mü regne med, at indvoldorme altid vil vÌre til stede i en vis udstrÌkning, nür besÌtningen har adgang til udendørs arealer. FuldstÌndig udryddelse er ikke mulig.
I dag findes der kun konventionelle antiparasitÌre midler til behandling og kontrol af parasitÌre infektioner. Disse midler anses ikke for at vÌre anvendelige, da tilbageholdelsestiderne er lange. Pü sigt bør man avlsmÌssigt arbejde mod at etablere specielle racer til udendørsproduktion som er resistente mod parasitÌre og andre infektioner.
Grovfoder
Forsøg med tildeling af grovfoder har haft en positiv effekt pü Ìgproduktion, forbrug af fuldfoder og der var en markant lavere dødelighed. Der kan iagttages mindre fjerpilning og en forbedring af fjerdragtens kvalitet, nür der gives grovfoder. Endelig kunne der hvad angür tarmsundhed konstateres en øget krüseaktivitet og øget fermentering i blindtarmene samt lavere antal af coliforme bakterier, laktose negative bakterier og enterokokker.
Pü temamødet pü Forskningscenter Foulum, berettede flere landmÌnd om grÌsrodsprojekterne, og deres resultater og erfaringer er beskrevet i denne rapport. I sit afsnit vurderer Arne BÌk Jensen bl.a., at det økologiske opdrÌt og anvendelsen af kyllingemødre har vÌret en succes idet:
Kyllingerne har levet under forhold, som har givet en forøgelse af dyrevelfÌrden.
Indeklimaet i opdrÌtsstalden har vÌret godt som følge af et tørt gulv
Energiforbruget er blevet reduceret
Den tidlige prĂŚgning har haft sin virkning
I ÌglÌgningsstalden sidder ca. 90 pct. af hønerne pü siddepindene om natten efter ca. 14 dage
Noget tyder pü, at de høner, som ikke kommer pü pindene om natten, ogsü lÌgger deres Ìg pü gulvet, hvor de overnatter. Hønerne pü siddepindene har en bedre redesøgningsadfÌrd
Ved indsÌtning ligger hønerne et pÌnt stykke over normen for vÌg
Finding 2-Edge and 2-Vertex Strongly Connected Components in Quadratic Time
We present faster algorithms for computing the 2-edge and 2-vertex strongly
connected components of a directed graph, which are straightforward
generalizations of strongly connected components. While in undirected graphs
the 2-edge and 2-vertex connected components can be found in linear time, in
directed graphs only rather simple -time algorithms were known. We use
a hierarchical sparsification technique to obtain algorithms that run in time
. For 2-edge strongly connected components our algorithm gives the
first running time improvement in 20 years. Additionally we present an -time algorithm for 2-edge strongly connected components, and thus
improve over the running time also when . Our approach
extends to k-edge and k-vertex strongly connected components for any constant k
with a running time of for edges and for vertices
The macro-economic effects of health co-benefits associated with climate change mitigation strategies
The UK government has specific targets for greenhouse gas (GHG) emission reduction to
lower the risk of dangerous climate change. Strategies to reduce GHG emissions are
sometimes perceived as expensive and difficult to implement but previous work has
demonstrated significant potential health co-benefits from âActive Travel and low carbon
drivingâ, âHousing Insulation/Ventilationâ, and âHealthy Dietâ scenarios which may be
attractive to policymakers. Here a Computable General Equilibrium model is used to assess
the financial effects of such health co-benefits on the wider economy including changes in
labour force, social security payments and healthcare costs averted. Results suggest that for
all scenarios the financial impacts of the health co-benefits will be positive and increased
active travel in particular is likely to make a substantial contribution, largely due to health
care costs averted.
Strategies to reduce GHG emissions and improve health are likely to result in substantial and
increasing positive contributions to the economy which may offset some potential economic
costs and thereby be seen more favourably in times of economic austerity
The impact of Covid-19, associated behaviours and policies on the UK economy: A computable general equilibrium model
This is the final version. Available on open access from Elsevier via the DOI in this record.âŻWe estimate the potential impact of COVID-19 on the United Kingdom economy, including direct disease effects, preventive public actions and associated policies. A sectoral, whole-economy macroeconomic model was linked to a population-wide epidemiological demographic model to assess the potential macroeconomic impact of COVID-19, together with policies to mitigate or suppress the pandemic by means of home quarantine, school closures, social distancing and accompanying business closures. Our simulations indicate that, assuming a clinical attack rate of 48% and a case fatality ratio of 1.5%, COVID-19 alone would impose a direct health-related economic burden of ÂŁ39.6bn (1.73% of GDP) on the UK economy. Mitigation strategies imposed for 12 weeks reduce case fatalities by 29%, but the total cost to the economy is ÂŁ308bn (13.5% of GDP); ÂŁ66bn (2.9% of GDP) of which is attributable to labour lost from working parents during school closures, and ÂŁ201bn (8.8% of GDP) of which is attributable to business closures. Suppressing the pandemic over a longer period of time may reduce deaths by 95%, but the total cost to the UK economy also increases to ÂŁ668bn (29.2% of GDP), where ÂŁ166bn (7.3% of GDP) is attributable to school closures and 502bn (21.9% of GDP) to business closures. Our analyses suggest Covid-19 has the potential to impose unprecedented economic costs on the UK economy, and whilst public actions are necessary to minimise mortality, the duration of school and business closures are key to determining the economic cost. The initial economic support package promised by the UK government may be proportionate to the costs of mitigating Covid-19, but without alternative measures to reduce the scale and duration of school and business closures, the economic support may be insufficient to compensate for longer term suppression of the pandemic which could generate an even greater health impact through major recession.EU Horizon 202
Adaptive introgression underlies polymorphic seasonal camouflage in snowshoe hares
Snowshoe hares (Lepus americanus) maintain seasonal camouflage by molting to a white winter coat, but some hares remain brown during the winter in regions with low snow cover. We show that cis-regulatory variation controlling seasonal expression of the Agouti gene underlies this adaptive winter camouflage polymorphism. Genetic variation at Agouti clustered by winter coat color across multiple hare and jackrabbit species, revealing a history of recurrent interspecific gene flow. Brown winter coats in snowshoe hares likely originated from an introgressed black-tailed jackrabbit allele that has swept to high frequency in mild winter environments. These discoveries show that introgression of genetic variants that underlie key ecological traits can seed past and ongoing adaptation to rapidly changing environments. (c) The Authors, Some Rights Reserved
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