8 research outputs found
Within-Host Dynamics of Multi-Species Infections:Facilitation, Competition and Virulence
No full textHost individuals are often infected with more than one parasite species (parasites defined broadly, to include viruses and bacteria). Yet, research in infection biology is dominated by studies on single-parasite infections. A focus on single-parasite infections is justified if the interactions among parasites are additive, however increasing evidence points to non-additive interactions being the norm. Here we review this evidence and theoretically explore the implications of non-additive interactions between co-infecting parasites. We use classic Lotka-Volterra two-species competition equations to investigate the within-host dynamical consequences of various mixes of competition and facilitation between a pair of co-infecting species. We then consider the implications of these dynamics for the virulence (damage to host) of co-infections and consequent evolution of parasite strategies of exploitation. We find that whereas one-way facilitation poses some increased virulence risk, reciprocal facilitation presents a qualitatively distinct destabilization of within-host dynamics and the greatest risk of severe disease.</p
Single Port Laparoscopic Surgery for Complex Crohn's Disease Is Safe with a Lower Conversion Rate
No full textThe Impact of Health Insurance Schemes for the Informal Sector in Low- and Middle-Income Countries: A Systematic Review
No full textThis paper summarizes the literature on the impact of state subsidized or social health insurance schemes that have been offered, mostly on a voluntary basis, to the informal sector in low-and middle-income countries. A substantial number of papers provide estimations of average treatment on the treated effect for insured persons. We summarize papers that correct for the problem of self-selection into insurance and papers that estimate the average intention to treat effect. Summarizing the literature was difficult because of the lack of (1) uniformity in the use of meaningful definitions of outcomes that indicate welfare improvements and (2) clarity in the consideration of selection issues. We find the uptake of insurance schemes, in many cases, to be less than expected. In general, we find no strong evidence of an impact on utilization, protection from financial risk, and health status. However, a few insurance schemes afford significant protection from high levels of out-of-pocket expenditures. In these cases, however, the impact on the poor is weaker. More information is needed to understand the reasons for low enrollment and to explain the limited impact of health insurance among the insured. JEL codes: I10, I15. © The Author 2012. Published by Oxford University Press on behalf of the International Bank for Reconstruction and Development/ THE WORLD BANK. All rights reserved
The factors which influence the selection of physical targets by terrorist groups
No full textThe aim of terrorism is to influence a group of people
or institutions - the psychological target or targets - by
attacking the appropriate physical targets in order to prompt
the desired response. Several factors influence the selection
of physical targets by non-state terrorist groups. These
include the ideology of the terrorist group concerned, the
strategy adopted by the group and its capabilities, its need
to take account of external opinion - including that of
supporters, the measures adopted to protect likely targets,
and the security environment within which the terrorist group
operates. In addition, decision-making is affected by the
dynamics within the group which are in turn affected by the
psychological pressures of clandestinity and the frequent
risk of death or capture which many terrorists run.
The relationship between these factors varies from
group to group, which is inevitable given the idiosyncratic
nature of most terrorist groups, and the different
circumstances in which they find themselves. However, it can
generally be said that ideology sets out the moral framework
within which terrorists operate - and which determines
whether terrorists judge it to be legitimate to attack a
range of target. After this, the determination of which
targets it will actually be beneficial to attack depends upon
the strategy which the group has adopted as a means of
achieving its political objectives. The determination of
their strategic objectives depends upon the effects which the
terrorists hope their attacks will achieve. Thus, strategy
further refines the range of targets initially delimited by
the group's ideology.
The other factors mentioned tend to act as constraints
upon the group, partly - as with security measures - in
restricting them from carrying out the types of attacks which
they would desire but also in encouraging them to carry out
attacks on certain targets in the hope of gaining benefits
such as the approval of their supporters, or of gaining
publicity for their cause. Underlying all of this is the
human factor, whereby relations within the group, the impact
of psychological pressure, and individual differences in
moral judgements may influence the targets chosen by
terrorists
ВОЗМОЖНОСТИ ПРИМЕНЕНИЯ ЛАКТОФЕРРИНА У ДЕТЕЙ ПЕРВОГО ГОДА ЖИЗНИ
No full textThe author summarizes the results of research of the antibacterial, antiviral and antifungal properties of multifunctional human protein — lactoferrin, in order to determine the prospects for its use in the prevention and treatment of infectious diseases of children in their first year of life. The mechanisms of anti-infectious effect of this protein with breastfed children have been described. Basic differences between human lactoferrin and cattle lactoferrin have been shown. Biotechnology of obtaining recombinant human lactoferrin from the milk of genetically engineered dairy animals (goat-producers) has been described. According to the studies, both by physical and chemical parameters and biological activity, human lactoferrin, obtained from milk-producing goats, corresponds to its natural counterpart.В статье обобщены результаты исследований, посвященных изучению антибактериальных, противовирусных и противогрибковых свойств многофункционального белка человека — лактоферрина, для определения перспектив его применения с целью профилактики и лечения инфекционной патологии у детей первого года жизни. Описаны механизмы противоинфекционного действия этого белка у детей, находящихся на грудном вскармливании. Показаны основные различия между лактоферрином человека и лактоферрином крупного рогатого скота. Описана биотехнология получения рекомбинантного лактоферрина человека из молока генно-инженерных молочных животных (коз-продуцентов). Согласно проведенным исследованиям, как по физико-химическим параметрам, так и по биологической активности лактоферрин человека, выделенный из молока коз-продуцентов, соответствует его природному аналогу
Hetrocyclic methacrylate systems as vehicles for the release of active species.
No full textPhDThe room temperature polymerising heterocyclic polymer system, poly(ethyl
methacrylate)/tetrahydrofurfuryl methacrylate (PEM/THFM) has been shown
previously to be biocompatible and supported tissue repair, specifically for bone
and cartilage, and biologically inert when in contact with the dental pulp. It
proved more effective, than other glassy methacrylates in the release of active
species.
The PEM/THFM system is a rigid material. The aim of this study was to develop
and characterise the use of this system as a flexible patch, for application and
retention to the buccal mucosa, thus facilitating sustained regulated release.
Model species, dextrans, were used to represent macromolecular drugs whereby
the effect of molecular weight could be studied. N-methyl pyrrolidone was added
to the polymer system as a biocompatible plasticiser to enhance molecular
mobility, and hence the transport of species. The effect of the addition of chitosan
was also studied, due to its bioadhesiveness and permeation enhancing ability.
A range of systems was investigated both in terms of water and species release.
The release of the agent was measured by a fluorometer, the leachable
components by HPLC and Confocal microscopy demonstrated the transport of
water and active species through the system. Immunological and viability studies
established whether the leachants or released components of the polymeric
systems had an inflammatory or irritant action on `in vitro' stratified epithelium.
The addition of N-methyl pyrrolidone, dextran and chitosan substantially
increased water uptake, thus affecting the release kinetics. Analysis of the
kinetics of water uptake showed Case I, combination of Case I and Case II, and
Case II kinetics, depending on the systems studied. Dextran release was largely
diffusion controlled, from which diffusion coefficients were calculated; the
amount released varied between the systems studied
Perception of, and adjustment to, drought hazard by farmers in southern SRI Lanka
No full textIn Sri Lanka, two thirds of the land mass lies within the Dry Zone where agriculture is the most important economic activity. In this climatic zone, rainfall is highly uncertain, seasonal, and limited to a few months. Consequently, the farmers in the area have to face drought as a natural hazard. This study focusses on how the farmers in the southern Dry Zone of Sri Lanka perceive drought as a hazard, the adjustments they make to reduce their vulnerability to droughts and how human behaviour affects the growing hazardousness of the study area. The results of this study show that the farmers in the study area have perceived drought as one of their major problems, and that the vulnerability to this natural phenomenon is growing as a result of the power abuse and environmental mismanagement of those high ranking people responsible. However, the farmers’ deeper understanding regarding their living environment (natural and man-made) has enhanced their power to combat the hazardous effects of droughts by way of a variety of adjustments. Considering and studying the above problems and issues the researcher has come to some conclusions and has put forward some suggestions, the most important of which, lie with changing the self-centered attitudes and activities of the powerful people in the direction of a socially and environmentally more sustainable and wholesome path
