409 research outputs found
The current concept of primary IgA deficiency and its prevalence in Iceland
Neðst á síðunni er hægt að nálgast greinina í heild sinni með því að smella á hlekkinn View/OpenIgA deficiency is among the most common primary immune deficiency known. Its prevalence, ranging from 1/324-1/1850, depends upon the study group geographic location and its ethnicity. IgA deficiency is commonly associated with other immune defects such as IgG2, and IgG4 deficiency. In addition, ataxia telangiectasia has been associated with IgA deficiency as well. The clinical significans of IgA deficiency is presently unclear. However, increased susceptibility to atopy, autoimmunity, infections and cancer has been reported. Furthermore, majority of these diseases are bound to the mucosal surfaces; the organ where IgA is thought to have its most protective role. Recent studies focusing on the genealogy of primary IgA deficiency have found linkages to chromosome 6, 14, 18 and 22. In addition, a link to certain HLA haplotypes has been reported. Thus, further studies into the immunogenetics of IgA deficiency are needed, particularly focusing upon the question why some individuals with IgA deficiency are prone to diseases whereas others are not. In this article some of these questions are addressed, and the current literature on the topic reviewed.IgA skortur er einn algengasti meðfæddi ónæmisgallinn og ræðst algengi hans meðal annars af kynþætti og þjóðerni. Hjá þjóðum N-Evrópu er algengið á bilinu 1/400-1/700. Einnig er þekkt að aðrir ónæmisgallar eins og IgG2 skortur og Louis-Bar heilkenni (ataxia telangiectasia) finnist hjá einstaklingum með IgA skort. IgA finnst í hvað mestum mæli á yfirborði slímhúðarinnar. Því er athyglivert að IgA skortur eykur líkur einstaklinga á að fá sjúkdóma er herja einna helst á slímhúðina og má þar nefna endurteknar sýkingar, ofnæmi og sjálfsofnæmissjúkdóma. Auk þess virðist þessum einstaklingum hættara við að fá krabbamein. Komið hefur í ljós að í sumum tilvikum hefur IgA skortur legið í ættum. Ættfræðilegar rannsóknir hafa þannig leitt í ljós tengsl við genasvæði á litningum 6, 14, 18 og 22. Auk þess virðast ákveðnar HLA samsætur hafa sterk tengsl við sjúkdóminn. Þrátt fyrir ítarlegar rannsóknir á orsökum og afleiðingum IgA skorts er mörgum lykilspurningum enn ósvarað og þá sérstaklega hvaða aðrir hugsanlegir virkir áhættuþættir leiða til ofangreindra sjúkdóma
Humus- und Nährstoffhaushalt in der ökologischen Landwirtschaft: Einfluss von Bodenbearbeitung und Düngung
Gait and Force Analysis of Provoked Pig Gait on Clean and Fouled Concrete Surfaces
Gait and force analysis have proven to be useful methods in linking claw injuries to surface material conditions. To determine the relationship between claw disorder and floor properties such as friction and surface abrasiveness, the factors controlling gait must be characterised. The effects of fouled concrete floor conditions on the gait of 10 pigs walking in a curve, using kinematics and kinetics to record gait parameters and slip frequency are described and compared with clean conditions. Pigs adapted to fouled floor conditions by reducing their walking speed and stride length, using a higher number of 3-foot support phases and by lowering diagonality. This adaption produced lower vertical forces, a twofold reduction in propulsion and outward stabilisation force and a threefold increase in braking force, without reducing the peak utilised coefficient of friction (UCOF). The UCOF values for both limbs of the curve walking pigs exceeded the recorded dynamic coefficient of friction and the corresponding UCOF values for pigs walking a straight line in fouled floor condition. As UCOF increased and available friction from the fouled floor surface decreased, this resulted in higher forward and backward slip frequency in both limbs for pigs walking in a curve. Pigs provoked to walk in a curve can adapt to fouled floor condition, but if the floor is heavily fouled this adaption is not sufficient to ensure safe walking
OGLE-2005-BLG-018: Characterization of Full Physical and Orbital Parameters of a Gravitational Binary Lens
We present the analysis result of a gravitational binary-lensing event
OGLE-2005-BLG-018. The light curve of the event is characterized by 2 adjacent
strong features and a single weak feature separated from the strong features.
The light curve exhibits noticeable deviations from the best-fit model based on
standard binary parameters. To explain the deviation, we test models including
various higher-order effects of the motions of the observer, source, and lens.
From this, we find that it is necessary to account for the orbital motion of
the lens in describing the light curve. From modeling of the light curve
considering the parallax effect and Keplerian orbital motion, we are able to
measure not only the physical parameters but also a complete orbital solution
of the lens system. It is found that the event was produced by a binary lens
located in the Galactic bulge with a distance kpc from the Earth.
The individual lens components with masses and are separated with a semi-major axis of AU and
orbiting each other with a period yr. The event demonstrates
that it is possible to extract detailed information about binary lens systems
from well-resolved lensing light curves.Comment: 19 pages, 6 figure
Unstable Flow and Non-Monotonic Constitutive Equation of Transient Networks
We have measured the nonlinear rheological response of a model transient
network over a large range of steady shear rates. The system is built up from
an oil in water droplet microemulsion into which a telechelic polymer is
incorporated. The phase behaviour is characterized which comprises a liquid-gas
phase separation and a percolation threshold. The rheological measurements are
performed in the one phase region above the percolation line. Shear thinning is
observed for all samples, leading in most cases to an unstable stress response
at intermediate shear rates. We built up a very simple mean field model which
involves the reduction of the residence time of the stickers in the droplets
due to the chain tensions at high shear. The computed constitutive equation is
non-monotonic with a range where the stress is a decreasing function of the
rate, a feature that indeed makes homogeneous flows unstable. The computed the
flow curves compare well to the experiments.Comment: mai 200
Epidemiologic evidence for asthma and exposure to air toxics: linkages between occupational, indoor, and community air pollution research.
Outdoor ambient air pollutant exposures in communities are relevant to the acute exacerbation and possibly the onset of asthma. However, the complexity of pollutant mixtures and etiologic heterogeneity of asthma has made it difficult to identify causal components in those mixtures. Occupational exposures associated with asthma may yield clues to causal components in ambient air pollution because such exposures are often identifiable as single-chemical agents (e.g., metal compounds). However, translating occupational to community exposure-response relationships is limited. Of the air toxics found to cause occupational asthma, only formaldehyde has been frequently investigated in epidemiologic studies of allergic respiratory responses to indoor air, where general consistency can be shown despite lower ambient exposures. The specific volatile organic compounds (VOCs) identified in association with occupational asthma are generally not the same as those in studies showing respiratory effects of VOC mixtures on nonoccupational adult and pediatric asthma. In addition, experimental evidence indicates that airborne polycyclic aromatic hydrocarbon (PAH) exposures linked to diesel exhaust particles (DEPs) have proinflammatory effects on airways, but there is insufficient supporting evidence from the occupational literature of effects of DEPs on asthma or lung function. In contrast, nonoccupational epidemiologic studies have frequently shown associations between allergic responses or asthma with exposures to ambient air pollutant mixtures with PAH components, including black smoke, high home or school traffic density (particularly truck traffic), and environmental tobacco smoke. Other particle-phase and gaseous co-pollutants are likely causal in these associations as well. Epidemiologic research on the relationship of both asthma onset and exacerbation to air pollution is needed to disentangle effects of air toxics from monitored criteria air pollutants such as particle mass. Community studies should focus on air toxics expected to have adverse respiratory effects based on biological mechanisms, particularly irritant and immunological pathways to asthma onset and exacerbation
Impact Factor: outdated artefact or stepping-stone to journal certification?
A review of Garfield's journal impact factor and its specific implementation
as the Thomson Reuters Impact Factor reveals several weaknesses in this
commonly-used indicator of journal standing. Key limitations include the
mismatch between citing and cited documents, the deceptive display of three
decimals that belies the real precision, and the absence of confidence
intervals. These are minor issues that are easily amended and should be
corrected, but more substantive improvements are needed. There are indications
that the scientific community seeks and needs better certification of journal
procedures to improve the quality of published science. Comprehensive
certification of editorial and review procedures could help ensure adequate
procedures to detect duplicate and fraudulent submissions.Comment: 25 pages, 12 figures, 6 table
Total costs and benefits of biomass in selected regions of the European Union
The paper describes results of the BioCosts project in which a comprehensive analysis of the economic and environmental performance of the energy use of biomass was carried out for selected existing facilities throughout the European Union. It is demonstrated that the appropriately organized use of biofuels has significant environmental advantages compared to the use of fossil fuels. Mitigation of global warming is the largest single incentive to use biofuels. However, only a few technologies are economically competitive under prevailing conditions, while others lead to up to 100% higher energy production costs than fossil fuels. Employment effects of using biofuels are small but positive.http://www.sciencedirect.com/science/article/B6V2S-41JM99D-4/1/514a3253589af4590f84544e2966bcb
Robust Phase Behavior of Model Transient networks
In order to study the viscoelastic properties of certain complex fluids which
are described in terms of a multiconnected transient network we have developed
a convenient model system composed of microemulsion droplets linked by
telechelic polymers. The phase behavior of such systems has two characteristic
features: a large monophasic region which consists of two sub-regions (a fluid
sol phase and a viscoelastic gel phase) separated by a percolation line and a
two phase region at low volume fraction with separation into a dilute sol phase
and a concentrated gel phase. From the plausible origin of these features we
expect them to be very similar in different systems. We describe here the phase
behavior of four different systems we prepared in order to vary the time scale
of the dynamical response of the transient network; they consist of the
combination of two oil(decane) in water microemulsions differing by the
stabilizing surfactant monolayer (Cetyl pyridinium chloride/octanol or
TX100/TX35) and of two telechelic polymers which are end-grafted poly (ethylene
oxide) chains, differing by the end-grafted hydrophobic aliphatic chains
(C12H25 or C18H37).Comment: April 9 200
Governance Conditions for Improving Quality Drinking Water Resources: the Need for Enhancing Connectivity
Realising the water quality objectives of the European Water Framework Directive have appeared to stagnate over the last decade all across Europe because of their highly complex nature. In the literature, interactive governance approaches tend to be regarded as the best way of dealing with complex water issues, but so far little empirical evidence has been reported on this perspective in regard to water quality issues. In this paper we have analysed how conditions of governance contribute to the realisation of water quality objectives at different types of drinking water resources in the Netherlands. The analysis demonstrates the importance of addressing different hydrological scales, institutional levels and sectors and thus enhance connectivity in order to improve water quality. The two other important conditions of governance approaches for water quality improvement which were identified are the use of joint fact-finding to gain a shared perception of risks, and the use of explicit decision-making and close monitoring of outcomes (re. water quality improvement), both of which contribute to this enhanced connectivity
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