235 research outputs found
Real-time testing of the on-site warning algorithm in southern California and its performance during the July 29 2008 M_w5.4 Chino Hills earthquake
The real-time performance of the τ_c -P_d on-site early warning algorithm currently is being tested within the California Integrated Seismic Network (CISN). Since January 2007, the algorithm has detected 58 local earthquakes in southern California and Baja with moment magnitudes of 3.0 ≤ M_w ≤ 5.4. Combined with newly derived station corrections the algorithm allowed for rapid determination of moment magnitudes and Modified Mercalli Intensity (MMI) with uncertainties of ±0.5 and ±0.7 units, respectively. The majority of reporting delays ranged from 9 to 16 s. The largest event, the July 29 2008 M_w5.4 Chino Hills earthquake, triggered a total of 60 CISN stations in epicentral distances of up to 250 km. Magnitude predictions at these stations ranged from M_w4.4 to M_w6.5 with a median of M_w5.6. The closest station would have provided up to 6 s warning at Los Angeles City Hall, located 50 km to the west-northwest of Chino Hills
Characterization of Megatrypanum trypanosomes from European Cervidae
Megatrypanum trypanosomes have been isolated from a number of different European Cervidae, but on the basis of morphology it has not been possible to define the species to which these isolates belong. We isolated Trypanosoma (Megatrypanum) theileri from 10 cattle, and Megatrypanum trypanosomes from 11 fallow deer (Cervus dama), 9 red deer (Cervus elaphus), and 4 roe deer (Capreolus capreolus) by blood culture on a biphasic medium (NNN agar slopes). Trypanosomes were propagated in Schneider's Drosophila medium and characterized by isoenzyme analysis and molecular karyotyping. Isocitrate dehydrogenase and phosphoglucomutase were visualized after starch gel electrophoresis of trypanosome lysates. By cluster analysis of this data all isolates from deer were clearly separated from the T. (M.) theileri isolates from cattle. Isolates from roe deer were different not only from T. (M.) theileri but also from the other deer isolates. Isolates from fallow deer and red deer were grouped together. Thus, there are probably at least two different species of Megatrypanum trypanosomes in the three Cervidae. One parasitizing roe deer, the other, apparently less host specific species, infecting red deer and fallow deer. Separation of the chromosomes of Megatrypanum trypanosomes by pulsed-field gradient gel electrophoresis (PFGE) showed that each isolate contained a large number (> 18) of chromosomes ranging in size from 300 to > 2200 kb. The molecular karyotypes were similar for all isolates, although no isolate was identical to anothe
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A correlative analysis of gold nanoparticles internalized by A549 cells
Fluorescently labeled nanoparticles are widely used to investigate nanoparticle cell interactions by fluorescence microscopy. Owing to limited lateral and axial resolution, nanostructures (<100 nm) cannot be resolved by conventional light microscopy techniques. Especially after uptake into cells, a common fate of the fluorescence label and the particle core cannot be taken for granted. In this study, a correlative approach is presented to image fluorescently labeled gold nanoparticles inside whole cells by correlative light and electron microscopy (CLEM). This approach allows for detection of the fluorescently labeled particle shell as well as for the gold core in one sample. In this setup, A549 cells are exposed to 8 nm Atto 647N-labeled gold nanoparticles (3.3 × 109 particles mL−1, 0.02 μg Au mL−1) for 5 h and are subsequently imaged by confocal laser scanning microscopy (CLSM) and transmission electron microscopy (TEM). Eight fluorescence signals located at different intracellular positions are further analyzed by TEM. Five of the eight fluorescence spots are correlated with isolated or agglomerated gold nanoparticles. Three fluorescence signals could not be related to the presence of gold, indicating a loss of the particle shell
Changes in wave climate over the northwest European shelf seas during the last 12,000 years
Because of the depth attenuation of wave orbital velocity, wave-induced bed shear stress is much more sensitive to changes in total water depth than tidal-induced bed shear stress. The ratio between wave- and tidal-induced bed shear stress in many shelf sea regions has varied considerably over the recent geological past because of combined eustatic changes in sea level and isostatic adjustment. In order to capture the high-frequency nature of wind events, a two-dimensional spectral wave model is here applied at high temporal resolution to time slices from 12 ka BP to present using paleobathymetries of the NW European shelf seas. By contrasting paleowave climates and bed shear stress distributions with present-day conditions, the model results demonstrate that, in regions of the shelf seas that remained wet continuously over the last 12,000 years, annual root-mean-square (rms) and peak wave heights increased from 12 ka BP to present. This increase in wave height was accompanied by a large reduction in the annual rms wave- induced bed shear stress, primarily caused by a reduction in the magnitude of wave orbital velocity penetrating to the bed for increasing relative sea level. In regions of the shelf seas which remained wet over the last 12,000 years, the annual mean ratio of wave- to (M-2) tidal-induced bed shear stress decreased from 1 (at 12 ka BP) to its present-day value of 0.5. Therefore compared to present- day conditions, waves had a more important contribution to large-scale sediment transport processes in the Celtic Sea and the northwestern North Sea at 12 ka BP
A New Trigger Criterion for Improved Real-Time Performance of Onsite Earthquake Early Warning in Southern California
We have implemented and tested an algorithm for onsite earthquake early warning (EEW) in California using the infrastructure of the Southern California Seismic Network (SCSN). The algorithm relies on two parameters derived from the initial 3 sec of P waveform data at a single seismic sensor: period parameter τ_c and high-pass filtered displacement amplitude P_d. Previous studies have determined empirical relationships between c and the moment magnitude M_w of an earthquake, and between P_d and the peak ground velocity (PGV) at the site of observation. In 2007, seven local earthquakes in southern California with 4.0≤M_L≤4.7 have triggered the calculation of M_w and PGV by the EEW algorithm. While the mean values of estimated parameters were in the expected range, the scatter was large, in particular for the smallest events. During the same time period the EEW algorithm produced a large number of false triggers due to low trigger thresholds. To improve the real-time performance of the onsite approach, we have developed a new trigger criterion that is based on combinations of observed τ _c and P_d values. This new criterion removes 97% of previous false triggers and leads to a significant reduction of the scatter in magnitude estimates for small earthquakes
The {\eta}'-carbon potential at low meson momenta
The production of mesons in coincidence with forward-going
protons has been studied in photon-induced reactions on C and on a
liquid hydrogen (LH) target for incoming photon energies of 1.3-2.6 GeV at
the electron accelerator ELSA. The mesons have been identified
via the decay
registered with the CBELSA/TAPS detector system. Coincident protons have been
identified in the MiniTAPS BaF array at polar angles of . Under these kinematic constraints the
mesons are produced with relatively low kinetic energy (
150 MeV) since the coincident protons take over most of the momentum of the
incident-photon beam. For the C-target this allows the determination of the
real part of the -carbon potential at low meson momenta by
comparing with collision model calculations of the kinetic energy
distribution and excitation function. Fitting the latter data for
mesons going backwards in the center-of-mass system yields a potential depth of
V = (44 16(stat)15(syst)) MeV, consistent with earlier
determinations of the potential depth in inclusive measurements for average
momenta of 1.1 GeV/. Within the experimental
uncertainties, there is no indication of a momentum dependence of the
-carbon potential. The LH data, taken as a reference to check
the data analysis and the model calculations, provide differential and integral
cross sections in good agreement with previous results for
photoproduction off the free proton.Comment: 9 pages, 13 figures. arXiv admin note: text overlap with
arXiv:1608.0607
Photoproduction of eta mesons from the neutron: cross sections and double polarization observable E
Photoproduction of mesons from neutrons} \abstract{Results from
measurements of the photoproduction of mesons from quasifree protons and
neutrons are summarized. The experiments were performed with the CBELSA/TAPS
detector at the electron accelerator ELSA in Bonn using the
decay. A liquid deuterium target was used for the
measurement of total cross sections and angular distributions. The results
confirm earlier measurements from Bonn and the MAMI facility in Mainz about the
existence of a narrow structure in the excitation function of . The current angular distributions show a forward-backward
asymmetry, which was previously not seen, but was predicted by model
calculations including an additional narrow state. Furthermore, data
obtained with a longitudinally polarized, deuterated butanol target and a
circularly polarized photon beam were analyzed to determine the double
polarization observable . Both data sets together were also used to extract
the helicity dependent cross sections and . The
narrow structure in the excitation function of
appears associated with the helicity-1/2 component of the reaction
Experimental constraints on the -nucleus real potential
In a search for mesic states, the production of -mesons in
coincidence with forward going protons has been studied in photon induced
reactions on C for incident photon energies of 1250 - 3100 MeV. The
pairs from decays of bound or quasi-free -mesons have
been measured with the CBELSA/TAPS detector system in coincidence with protons
registered in the MiniTAPS forward array. Structures in the total energy
distribution of the pairs, which would indicate the population
and decay of bound B states, are not observed. The
cross section of 0.3 nb/MeV/sr observed in the bound state energy regime
between -100 and 0 MeV may be accounted for by yield leaking into the bound
state regime because of the large in-medium width of the -meson. A
comparison of the measured total energy distribution with calculations suggests
the real part of the B potential to be small and only
weakly attractive with 35(stat) 20(syst) MeV
in contrast to some theoretical predictions of attractive potentials with a
depth of 100 - 150 MeV.Comment: 13 pages, 8 figure
First measurement of the helicity asymmetry for in the resonance region
The first measurement of the helicity dependence of the photoproduction cross
section of single neutral pions off protons is reported for photon energies
from 600 to 2300\,MeV, covering nearly the full solid angle. The data are
compared to predictions from the SAID, MAID, and BnGa partial wave analyses.
Strikingly large differences between data and predictions are observed which
are traced to differences in the helicity amplitudes of well known and
established resonances. Precise values for the helicity amplitudes of several
resonances are reported
The polarization observables T, P, and H and their impact on multipoles
Data on the polarization observables T, P, and H for the reaction are reported. Compared to earlier data from other experiments, our
data are more precise and extend the covered range in energy and angle
substantially. The results were extracted from azimuthal asymmetries measured
using a transversely polarized target and linearly polarized photons. The data
were taken at the Bonn electron stretcher accelerator ELSA with the CBELSA/TAPS
detector. Within the Bonn-Gatchina partial wave analysis, the new polarization
data lead to a significant narrowing of the error band for the multipoles for
neutral-pion photoproduction
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