Natural Nuclear Reactor Oklo and Variation of Fundamental Constants Part 1: Computation of Neutronics of Fresh Core

Using modern methods of reactor physics we have performed full-scale calculations of the natural reactor Oklo. For reliability we have used recent version of two Monte Carlo codes: Russian code MCU REA and world wide known code MCNP (USA). Both codes produce similar results. We have constructed a computer model of the reactor Oklo zone RZ2 which takes into account all details of design and composition. The calculations were performed for three fresh cores with different uranium contents. Multiplication factors, reactivities and neutron fluxes were calculated. We have estimated also the temperature and void effects for the fresh core. As would be expected, we have found for the fresh core a significant difference between reactor and Maxwell spectra, which was used before for averaging cross sections in the Oklo reactor. The averaged cross section of Sm-149 and its dependence on the shift of resonance position (due to variation of fundamental constants) are significantly different from previous results. Contrary to results of some previous papers we find no evidence for the change of the fine structure constant in the past and obtain new, most accurate limits on its variation with time: -4 10^{-17}year^{-1} < d alpha/dt/alpha < 3 10^{-17} year^{-1} A further improvement in the accuracy of the limits can be achieved by taking account of the core burnup. These calculations are in progress.Comment: 25 pages, 14 figures, 12 tables, minor corrections, typos correcte

Porewater methane transport within the gas vesicles of diurnally migrating Chaoborus spp.: An energetic advantage

We show that diurnally migrating Chaoborus sp. (phantom midge larvae), which can be highly abundant in eutrophic lakes with anoxic bottom, utilises sediment methane to inflate their tracheal sacs, which provides positive buoyancy to aid vertical migration. This process also effectively transports sediment methane bypassing oxidation to the upper water column, adding to the total methane outflux to the atmosphere

Dementia diagnostics in primary care : a representative 8-year follow-up study in Lower Saxony, Germany

AIM: To investigate whether primary-care physicians' competency regarding dementia diagnostics improved from 1993 to 2001. METHODS: In a representative follow-up survey 122 out of 170 (71.8%) family physicians (FPs) were randomly assigned to 2 written case samples presenting patients with slight memory impairment (case 1a: female vs. case 1b: male) and moderate dementia [vascular type (case 2a) vs. Alzheimer's disease (case 2b)]. Potential diagnostic workup was inquired by a structured face-to-face interview. RESULTS: 'Basic' diagnostics like history taking or laboratory investigations were considered in the first place. In case 1, neuropsychological screening was significantly more frequently considered at follow-up (19.3% in 1993 vs. 31.1% in 2001); it still would have been applied rarely in case 2 (2a: 14.1 vs. 14.8%; 2b: 23.5 vs. 24.6%). Neuroimaging remained not to be considered as a standard procedure, and only a minority of FPs would have performed a screening for depression (2001: 1a: 6.7%; 1b: 11.3%; 2a: 0.0%; 2b: 1.6%). CONCLUSIONS: With regard to dementia diagnostics in primary care, guideline adherence remained low at follow-up. Structured training efforts aiming at FPs appear to be necessary

Primary care physicians' attitudes related to cognition enhancers in early dementia : a representative eight-year follow-up study in Lower Saxony, Germany

OBJECTIVE: By means of a representative follow-up survey, we investigated changes in family physicians' (FPs) attitudes towards cognition enhancers in early dementia during 1993 and 2001. METHODS: One hundred and twenty-two FPs (response rate 71.8%) in Lower Saxony, Germany, were randomly assigned to one of two written case samples presenting a patient with cognitive decline suggestive of early Alzheimer's disease (DAT; case A: female patient vs case B: male patient). Using a structured face-to-face interview, they were asked to suggest their potential drug treatment. The results were compared to corresponding data from our previous survey in 1993. RESULTS: FPs' readiness to start antidementia drug treatment decreased from 70.4% in 1993 to 43.4% at follow-up, although underlying DAT was significantly more frequently suggested (11.0% vs 26.2%, p > 0.05). Substances with questionable efficacy such as Piracetame were prescribed less frequently in 2001 whereas evidence-based medication like cholinesterase inhibitors (ChEIs) failed to compensate for this drop. Compared to 1993, when 55.2% of FPs expected no therapeutic impact, at follow-up, 75.4% expected slowdown of disease progression, stabilisation or improvement of symptoms (p > 0.05). CONCLUSIONS: Our results demonstrate a significant decrease of therapeutic nihilism in primary care within eight years. However, in patients with suspicion of DAT, this is not reflected accordingly in potential treatment

Developing innovative solutions for traffic noise control in Europe

The objective of the DISTANCE project is to provide NRAs with guidelines to improve the optimization of traffic noise abatement in the future on main road networks. The guidelines will help to improve quality of noise maps and outline which noise asset information should ideally be gathered. Accurate noise maps will allow more reliable identification of areas where noise abatement is required. A vision for future noise abatement measures is developed. The traffic and road network, as it is expected to develop in the future, is investigated, based on development of traffic volumes, composition, noise emissions and low-noise pavements on the network