3,653 research outputs found
Adaptive stochastic Galerkin FEM for lognormal coefficients in hierarchical tensor representations
Stochastic Galerkin methods for non-affine coefficient representations are
known to cause major difficulties from theoretical and numerical points of
view. In this work, an adaptive Galerkin FE method for linear parametric PDEs
with lognormal coefficients discretized in Hermite chaos polynomials is
derived. It employs problem-adapted function spaces to ensure solvability of
the variational formulation. The inherently high computational complexity of
the parametric operator is made tractable by using hierarchical tensor
representations. For this, a new tensor train format of the lognormal
coefficient is derived and verified numerically. The central novelty is the
derivation of a reliable residual-based a posteriori error estimator. This can
be regarded as a unique feature of stochastic Galerkin methods. It allows for
an adaptive algorithm to steer the refinements of the physical mesh and the
anisotropic Wiener chaos polynomial degrees. For the evaluation of the error
estimator to become feasible, a numerically efficient tensor format
discretization is developed. Benchmark examples with unbounded lognormal
coefficient fields illustrate the performance of the proposed Galerkin
discretization and the fully adaptive algorithm
Integral Management: Adaptationsmöglichkeiten und Modifikationserfordnerisse des Balanced-Scorecard-Konzeptes bei der Anwendung in Non-Profit-Organisationen
Non-Profit-Organizations of the Third Sector have lately gained an increasing importance both in scientific research and as far as their economical weight is concerned. Adapting the concept of the Balanced Scorecard for those organizations, their particularities need to be determined and based on the findings, the need of changes within and additions to the concept need to be questioned and discussed.Non-Profit-Organisationen, Balanced Scorecard, Controlling, Performance, Measurement
Uptake and fecal excretion of Coxiella burnetii by Ixodes ricinus and Dermacentor marginatus ticks
Background:
The bacterium Coxiella burnetii is the etiological agent of Q fever and is mainly transmitted via inhalation of infectious aerosols. DNA of C. burnetii is frequently detected in ticks, but the role of ticks as vectors in the epidemiology of this agent is still controversial. In this study, Ixodes ricinus and Dermacentor marginatus adults as well as I. ricinus nymphs were fed on blood spiked with C. burnetii in order to study the fate of the bacterium within putative tick vectors.
Methods:
Blood-feeding experiments were performed in vitro in silicone-membrane based feeding units. The uptake, fecal excretion and transstadial transmission of C. burnetii was examined by quantitative real-time PCR as well as cultivation of feces and crushed tick filtrates in L-929 mouse fibroblast cells and cell-free culture medium.
Results:
Ticks successfully fed in the feeding system with engorgement rates ranging from 29% (D. marginatus) to 64% (I. ricinus adults). Coxiella burnetii DNA was detected in the feces of both tick species during and after feeding on blood containing 105 or 106 genomic equivalents per ml blood (GE/ml), but not when fed on blood containing only 104 GE/ml. Isolation and cultivation demonstrated the infectivity of C. burnetii in shed feces. In 25% of the I. ricinus nymphs feeding on inoculated blood, a transstadial transmission to the adult stage was detected. Females that molted from nymphs fed on inoculated blood excreted C. burnetii of up to 106 genomic equivalents per mg of feces.
Conclusions:
These findings show that transstadial transmission of C. burnetii occurs in I. ricinus and confirm that I. ricinus is a potential vector for Q fever. Transmission from both tick species might occur by inhalation of feces containing high amounts of viable C. burnetii rather than via tick bites
Conceiving time?: women who do or do not conceive
This article explores the importance of time for an understanding of women's experiences of reproductive identity. In order to do this we draw on data from two separate qualitative research projects. The first project is concerned with the experiences of conception, pregnancy, childbirth and early motherhood in primagravidae, whilst the second focuses on the experiences of individuals (especially women) who defined themselves (at the time of the fieldwork, or some time previously) as 'involuntarily childless' and/or 'infertile'. These two areas are usually treated as separate; however this article explores similarities between them in terms of time and medicalisation. Our central concern then is with exploring the similarities of experience for women who do or do not conceive
Serological differentiation of antibodies against Rickettsia helvetica, R. raoultii, R. slovaca, R. monacensis and R. felis in dogs from Germany by a micro-immunofluorescent antibody test
Background Spotted Fever Group (SFG) Rickettsiae can cause febrile diseases
with or without rash in humans worldwide. In Germany only limited data are
available about their medical significance. Serological screening tests for
antibodies against rickettsiae usually only distinguish between SFG and Typhus
Group (TG) Rickettsiae due to the strong cross reactivities within the groups.
Seroprevalence rates in dogs, as possible sentinels for tick-borne diseases,
could serve as an indicator for the distribution of different Rickettsia
species. Methods In this study, a micro-immunofluorescence assay (micro-IFA)
was established for detection and differentiation of antibodies against five
Rickettsia species in dogs (R. helvetica, R. raoultii, R. slovaca, R.
monacensis and R. felis). Dogs that never left Germany (n = 605) previously
investigated with an SFG-ELISA were included in this study and screened at a
1:128 dilution. Endpoint titres of fifty randomly selected seropositive
samples of each of the five investigated regions in Germany were determined in
order to allow a differentiation of the causative Rickettsia species.
Sensitivity and specificity of the micro-IFA were compared with ELISA results
of the previous study. Results A total of 93.9% of the dogs were positive for
antibodies of the SFG Rickettsiae at the screening titer of 1:128.
Differentiation of SFG Rickettsiae with the micro-IFA was possible in 70.4%,
but in 29.6% of the cases the detected antibodies were not differentiable.
Considering a clear differentiation by a twofold titre difference between
observed reactions, the seroprevalence rates were 66.0% for R. helvetica, 2.8%
for R. raoultii, 1.6% for R. slovaca, but no serological reaction could be
clearly attributed to R. monacensis or R. felis. No statistically significant
regional differences were found for R. helvetica, R. slovaca and R. raoultii
comparing the five regions of Germany. Comparison of micro-IFA with ELISA
revealed a sensitivity of 82.0% and a specificity of 83.8% for the Rickettsia
SFG ELISA. Conclusions The micro-IFA is a useful serological tool to
differentiate antibodies against different Rickettsia species in dogs.
Seroprevalence rates in dogs correspond to the prevalence rates and
distribution of Rickettsia-carrying tick species
Нові інтелектуальні технології та методи оптимізації для дослідження складних систем
Protein transport into the endoplasmic reticulum (ER) is essential for all eukaryotic cells and evolutionary related to protein transport into and across the cytoplasmic membrane of eubacteria and archaea. It is based on amino-terminal signal peptides in the precursor polypeptides plus various transport components in cytosol plus ER and can occur either cotranslationally or posttranslationally. The two mechanisms merge at the heterotrimeric Sec61 complex in the ER membrane, which forms an aqueous polypeptide-conducting channel. Since the mammalian ER is also the main intracellular calcium storage organelle, the Sec61 complex is tightly regulated in its dynamics between the open and closed conformations by various ligands, such as precursor polypeptides at the cytosolic face and the Hsp70-type molecular chaperone BiP at the ER lumenal face (Hsp, heat shock protein). Furthermore, BiP binding to the incoming precursor polypeptide contributes to unidirectionality and efficiency of transport. Recent insights into the structural dynamics of the Sec61 complex and related complexes in eubacteria and archaea have various mechanistic and functional implications
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Foundation-funded journalism, Philanthrocapitalism and Tainted donors
Not-for-profit news organisations are increasingly funded by private foundations, supported by wealthy entrepreneurs. This raises a range of ethical dilemmas for journalists, which are particularly serious when their donors are alleged to have been involved in unethical or illegal activities. Although this is a relatively common occurrence in the non-profit sector, so far there has been no critical discussion of these issues in relation to foundation-funded journalism. In this article, we interrogate a rich and detailed case study of the relations between a nonprofit news organisation and a donor accused of being involved in a massive, international fraud scandal. We document how the news outlet justified their acceptance of this donor’s money; the defensive strategies they used to protect their reputation, organisational values and editorial freedom; and the conditions that ultimately led to journalists parting ways with the foundation. In so doing, we draw on ideas about philanthrocapitalism, stakeholders and resource dependence in order to develop Dunn’s (2010) model of how nonprofits respond to “tainted” donors
The role of wild canids and felids in spreading parasites to dogs and cats in Europe. Part I: Protozoa and tick-borne agents.
Over the last few decades, the world has witnessed radical changes in climate, landscape, and ecosystems. These events, together with other factors such as increasing illegal wildlife trade and changing human behaviour towards wildlife, are resulting into thinning boundaries between wild canids and felids and their domestic counterparts. As a consequence, the epidemiology of diseases caused by a number of infectious agents is undergoing profound readjustements, as pathogens adapt to new hosts and environments. Therefore, there is a risk for diseases of wildlife to spread to domestic carnivores and vice versa, and for zoonotic agents to emerge or re-emerge in human populations. Hence, the identification of the hazards arising from the co-habitation of these species is critical in order to plan and develop adequate control strategies against these pathogens. In the first of this two-part article, we review the role that wild canids and felids may play in the transmission of protozoa and arthropod-borne agents to dogs and cats in Europe, and provide an account of how current and future progress in our understanding of the ecology and epidemiology of parasites, as well as of host-parasite interactions, can assist efforts aimed at controlling parasite transmission.This is the accepted manuscript. The final version is available at http://dx.doi.org/10.1016/j.vetpar.2015.04.02
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