3,990 research outputs found
Construction and application of a questionnaire for the social scientific investigation of environmental noise effects
A social psychological questionnair has been developed to study the effects of environmental noise and was applied to 636 people living in 19 different areas of Hamburg. The theoretical foundations and the statistical means employed in its development are described. Four main reactions to noise are isolated statistically, and it is determined that these are moderated by several intervening variables, chief of which are coping capacity for noise, the perceived dangerousness of the noise souce, other daily loads and the individual's liability
Significant association of a M129V independent polymorphism in the 5\prime UTR of the PRNP gene with sporadic Creutzfeldt-Jakob disease in a large German case-control study
Background: A single nucleotide polymorphism (SNP) in the coding region of the prion protein gene (PRNP) at codon 129 has been repeatedly shown to be an associated factor to sporadic Creutzfeldt-Jakob disease (sCJD), but additional major predisposing DNA variants for sCJD are still unknown. Several previous studies focused on the characterisation of polymorphisms in PRNP and the prion-like doppel gene (PRND), generating contradictory results on relatively small sample sets. Thus, extensive studies are required for validation of the polymorphisms in PRNP and PRND.Methods: We evaluated a set of nine SNPs of PRNP and one SNP of PRND in 593 German sCJD patients and 748 German healthy controls. Genotyping was performed using MALDI-TOF mass spectrometry.Results: In addition to PRNP 129, we detected a significant association between sCJD and allele frequencies of six further PRNP SNPs. No significant association of PRND T174M with sCJD was shown. We observed strong linkage disequilibrium within eight adjacent PRNP SNPs, including PRNP 129. However, the association of sCJD with PRNP 1368 and PRNP 34296 appeared to be independent on the genotype of PRNP 129. We additionally identified the most common haplotypes of PRNP to be over-represented or under-represented in our cohort of patients with sCJD.Conclusion: Our study evaluated previous findings of the association of SNPs in the PRNP and PRND genes in the largest cohorts for association study in sCJD to date, and extends previous findings by defining for the first time the haplotypes associated with sCJD in a large population of the German CJD surveillance study
Synthetic metabolic pathways for photobiological conversion of CO2 into hydrocarbon fuel
Liquid fuels sourced from fossil sources are the dominant energy form for mobile transport today. The consumption of fossil fuels is still increasing, resulting in a continued search for more sustainable methods to renew our supply of liquid fuel. Photosynthetic microorganisms naturally accumulate hydrocarbons that could serve as a replacement for fossil fuel, however productivities remain low. We report successful introduction of five synthetic metabolic pathways in two green cell factories, prokaryotic cyanobacteria and eukaryotic algae. Heterologous thioesterase expression enabled high-yield conversion of native fatty acyl-acyl carrier protein (ACP) into free fatty acids (FFA) in Synechocystis sp. PCC 6803 but not in Chlamydomonas reinhardtii where the polar lipid fraction instead was enhanced. Despite no increase in measurable FFA in Chlamydomonas, genetic recoding and over-production of the native fatty acid photodecarboxylase (FAP) resulted in increased accumulation of 7-heptadecene. Implementation of a carboxylic acid reductase (CAR) and aldehyde deformylating oxygenase (ADO) dependent synthetic pathway in Synechocystis resulted in the accumulation of fatty alcohols and a decrease in the native saturated alkanes. In contrast, the replacement of CAR and ADO with Pseudomonas mendocina UndB (so named as it is responsible for 1-undecene biosynthesis in Pseudomonas) or Chlorella variabilis FAP resulted in high-yield conversion of thioesterase-liberated FFAs into corresponding alkenes and alkanes, respectively. At best, the engineering resulted in an increase in hydrocarbon accumulation of 8- (from 1 to 8.5 mg/g cell dry weight) and 19-fold (from 4 to 77 mg/g cell dry weight) for Chlamydomonas and Synechocystis, respectively. In conclusion, reconstitution of the eukaryotic algae pathway in the prokaryotic cyanobacteria host generated the most effective system, highlighting opportunities for mix-and-match synthetic metabolism. These studies describe functioning synthetic metabolic pathways for hydrocarbon fuel synthesis in photosynthetic microorganisms for the first time, moving us closer to the commercial implementation of photobiocatalytic systems that directly convert CO2 into infrastructure-compatible fuels
Epidemiological and clinical features of travel-associated cryptosporidiosis
ABSTRACTData concerning the clinical and epidemiological features of travel-associated cryptosporidiosis are lacking. In order to investigate the impact of this disease on travellers' health, a retrospective study was conducted at the Institute of Tropical Medicine, Berlin. In total, 57 cryptosporidial infections were identified between 2000 and 2004, resulting in a prevalence of 2.9% in patients with travel-associated diarrhoea. Travel to south-central Asia, especially India, was associated with a higher prevalence of infection than was travel to other destinations. Clinically, the disease resembled giardiasis, but fever and arthralgias seemed to occur more frequently
Near-Infrared Studies of V1280 Sco (Nova Scorpii 2007)
We present spectroscopic and photometric results of Nova V1280 Sco which was
discovered in outburst in early 2007 February. The large number of spectra
obtained of the object leads to one of the most extensive, near-infrared
spectral studies of a classical nova. The spectra evolve from a P-Cygni phase
to an emission-line phase and at a later stage is dominated by emission from
the dust that formed in this nova. A detailed model is computed to identify and
study characteristics of the spectral lines. Inferences from the model address
the vexing question of which novae have the ability to form dust. It is
demonstrated, and strikingly corroborated with observations, that the presence
of lines in the early spectra of low-ionization species like Na and Mg -
indicative of low temperature conditions - appear to be reliable indicators
that dust will form in the ejecta. It is theoretically expected that mass loss
during a nova outburst is a sustained process. Spectroscopic evidence for such
a sustained mass loss, obtained by tracing the evolution of a P-Cygni feature
in the Brackett gamma line, is presented here allowing a lower limit of 25-27
days to be set for the mass-loss duration. Photometric data recording the
nova's extended 12 day climb to peak brightness after discovery is used to
establish an early fireball expansion and also show that the ejection began
well before maximum brightness. The JHK light curves indicate the nova had a
fairly strong second outburst around 100 days after the first.Comment: Accepted in MNRAS. The paper contains 8 figures and 4 tables. Few
typographical errors were correcte
Eclipsing Binaries in the OGLE Variable Star Catalog. IV. The Pre-Contact, Equal-Mass Systems
We used the database of eclipsing binaries detected by the OGLE microlensing
project in the pencil-beam search volume toward Baade's Window to define a
sample of 74 detached, equal-mass, main-sequence binary stars with short
orbital periods in the range 0.19<P<8 days. The logarithmic slope of the period
distribution, logN propto (-0.8 pm 0.2) logP, was used to infer the
angular-momentum-loss (AML) efficiency for the late, rapidly-rotating members
of close binaries. It is very likely that the main cause of the negative slope
is a discovery selection bias that progressively increases with the orbital
period length. Assuming a power-law dependence for the correction for the bias:
bias propto -C logP (with C ge 0), the AML braking-efficiency exponent alpha in
dH/dt = P^-alpha can take any value alpha = (-1.1 pm 0.2) + C. Very simple
considerations of discovery biases suggest C simeq 4/3, which would give an AML
braking law very close to the "saturated" one, with no dependence on the
period. However, except for plausibility arguments, we have no firm data to
support this estimate of C, so that alpha remains poorly constrained. The
results signal the utmost importance of the detection bias evaluation for
variable star databases used in analyses similar to the one presented in this
study.Comment: accepted by AJ, October 1999. AASTEX-4. 9 PS figures and 3 table
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