A cost-effective method to quantify biological surface sediment reworking

We propose a simple and inexpensive method to determine the rate and pattern of surface sediment reworking by benthic organisms. Unlike many existing methods commonly used in bioturbation studies, which usually require sediment sampling, our approach is fully non-destructive and is well suited for investigating non-cohesive fine sediments in streams and rivers. Optical tracer (e.g., luminophores or coloured sand) disappearance or appearance is assessed through time based on optical quantification of surfaces occupied by tracers. Data are used to calculate surface sediment reworking (SSR) coefficients depicting bioturbation intensities. Using this method, we evaluated reworking activity of stream organisms (three benthic invertebrates and a fish) in laboratory microcosms mimicking pool habitats or directly in the field within arenas set in depositional zones. Our method was sensitive enough to measure SSR as low as 0.2 cm2.d-1, such as triggered by intermediate density (774 m-2) of Gammarus fossarum (Amphipoda) in microcosms. In contrast, complex invertebrate community in the field and a fish (Barbatula barabatula) in laboratory microcosms were found to yield to excessively high SSR (>60 cm2.d-1). Lastly, we suggest that images acquired during experiments can be used for qualitative evaluation of species-specific effects on sediment distribution

Search for composite and exotic fermions at LEP 2

A search for unstable heavy fermions with the DELPHI detector at LEP is reported. Sequential and non-canonical leptons, as well as excited leptons and quarks, are considered. The data analysed correspond to an integrated luminosity of about 48 pb^{-1} at an e^+e^- centre-of-mass energy of 183 GeV and about 20 pb^{-1} equally shared between the centre-of-mass energies of 172 GeV and 161 GeV. The search for pair-produced new leptons establishes 95% confidence level mass limits in the region between 70 GeV/c^2 and 90 GeV/c^2, depending on the channel. The search for singly produced excited leptons and quarks establishes upper limits on the ratio of the coupling of the excited fermio

Search for lightest neutralino and stau pair production in light gravitino scenarios with stau NLSP

Promptly decaying lightest neutralinos and long-lived staus are searched for in the context of light gravitino scenarios. It is assumed that the stau is the next to lightest supersymmetric particle (NLSP) and that the lightest neutralino is the next to NLSP (NNLSP). Data collected with the Delphi detector at centre-of-mass energies from 161 to 183 \GeV are analysed. No evidence of the production of these particles is found. Hence, lower mass limits for both kinds of particles are set at 95% C.L.. The mass of gaugino-like neutralinos is found to be greater than 71.5 GeV/c^2. In the search for long-lived stau, masses less than 70.0 to 77.5 \GeVcc are excluded for gravitino masses from 10 to 150 \eVcc . Combining this search with the searches for stable heavy leptons and Minimal Supersymmetric Standard Model staus a lower limit of 68.5 \GeVcc may be set for the stau mas

A trend towards the better assessment of a seismic hazard - the Hestia and Hestia Mapa systems

W artykule przedstawiono opracowane w Centrum EMAG systemy komputerowe Hestia i Hestia Mapa, których zadaniem jest wspomaganie pracowników stacji geofizycznych w kopalniach węgla kamiennego. Głównym zadaniem systemów jest gromadzenie i wizualizacja danych pochodzących z systemów monitorujących aktywność sejsmiczną wyrobiska. Na podstawie gromadzonych danych systemy generują ocenę zagrożenia tąpaniami metodami szczegółowymi (sejsmologiczną, sejsmoakustyczną, wierceń małośrednicowych) i metodą kompleksową, a także umożliwiają wizualizację zarejestrowanej sejsmiczności w kopalniach na mapach pokładowych. Oba systemy posiadają bogaty zestaw funkcji raportujących. W artykule przedstawiono również najnowsze prace związane z rozwojem systemów Hestia i Hestia Mapa.The Hestia and Hestia Mapa computer-aided systems developed by the EMAG Centre and helping personnel of geophysical stations in hard coal mines have been presented in the paper. The main task of those systems is acquisition and visualisation of data from seismic activity monitoring systems located in mine workings. On the basis of the data to be gathered, the systems generate the evaluation of a bump hazard made by detailed methods like seismological, seismoacoustic, small-diameter drilling ones as well as by a complex method. The systems allow also seismicity registered in mines to be visualized on the mining seam maps. The both systems have a rich set of reporting functions. The latest works on a development of the Hestia and Hestia Mapa systems have been presented in the paper as well