Highlights • The phytoplanktonic neurotoxin BMAA detected in human central nervous system. • 12 ALS patients and 13 controls examined for BMAA with UHPLC–MS/MS. • BMAA found in cerebrospinal fluid of ...1 ALS patient and 2 controls. • BMAA was not prevalent in ALS patients.
β-methylamino-L-alanine (BMAA), a neurotoxic nonprotein amino acid produced by most cyanobacteria, has been proposed to be the causative agent of devastating neurodegenerative diseases on the island ...of Guam in the Pacific Ocean. Because cyanobacteria are widespread globally, we hypothesized that BMAA might occur and bioaccumulate in other ecosystems. Here we demonstrate, based on a recently developed extraction and HPLC-MS/MS method and long-term monitoring of BMAA in cyanobacterial populations of a temperate aquatic ecosystem (Baltic Sea, 2007—2008), that BMAA is biosynthesized by cyanobacterial genera dominating the massive surface blooms of this water body. BMAA also was found at higher concentrations in organisms of higher trophic levels that directly or indirectly feed on cyanobacteria, such as zooplankton and various vertebrates (fish) and invertebrates (mussels, oysters). Pelagic and benthic fish species used for human consumption were included. The highest BMAA levels were detected in the muscle and brain of bottom-dwelling fishes. The discovery of regular biosynthesis of the neurotoxin BMAA in a large temperate aquatic eco-system combined with its possible transfer and bioaccumulation within major food webs, some ending in human consumption, is alarming and requires attention.
Measurement of the contribution of neutrons to hadron calorimeter signals Akchurin, N.; Berntzon, L.; Cardini, A. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
11/2007, Letnik:
581, Številka:
3
Journal Article
Recenzirano
Odprti dostop
The contributions of neutrons to hadronic signals from the DREAM calorimeter are measured by analyzing the time structure of these signals. The neutrons, which mainly originate from the evaporation ...stage of nuclear breakup in the hadronic shower development process, contribute through elastic scattering off protons in the plastic scintillating fibers which provide the
d
E
/
d
x
information in this calorimeter. This contribution is characterized by an exponential tail in the pulse shape, with a time constant of
∼
25
ns
. The relative contribution of neutrons to the signals increases with the distance from the shower axis. As expected, the neutrons do not contribute to the DREAM Cherenkov signals.
Results are presented of detailed measurements of the signals generated by high-energy electrons and muons in lead tungstate crystals. A significant fraction of the light produced in these crystals ...and detected by photomultiplier tubes is the result of the Cherenkov mechanism. This is concluded from the angular dependence of the signals and from their time structure. Depending on the orientation of the crystals and on the particle type, Cherenkov light may account for up to 15% of the total signals.
Dual-readout calorimetry with lead tungstate crystals Akchurin, N.; Berntzon, L.; Cardini, A. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
01/2008, Letnik:
584, Številka:
2
Journal Article
Recenzirano
Odprti dostop
Results are presented of beam tests in which a small electromagnetic calorimeter consisting of lead tungstate crystals was exposed to 50
GeV electrons and pions. This calorimeter was backed up by the ...DREAM Dual-Readout calorimeter, which measures the scintillation and Cherenkov light produced in the shower development, using two different media. The signals from the crystal calorimeter were analyzed in great detail in an attempt to determine the contributions from these two types of light to the signals, event by event. This information makes it possible to eliminate the dominating source of fluctuations and thus achieve an important improvement in hadronic calorimeter performance.
Results of detailed measurements of the Čerenkov light yield from lead tungstate (PbWO4) crystals are presented. A single crystal as well as a small homogeneous calorimeter (ECAL), consisting of 19 ...PbWO4 crystals, were exposed to electrons, muons and pions at the H4 beam line at CERN. It turns out that a significant fraction of the detected light is not the result of scintillation processes, but rather of the Čerenkov mechanism. This can be assessed from the analysis of both the angular dependence of the signals and their time structure. Detailed studies of the ECAL signals, corroborated by the measurements taken with the Dual-Readout calorimeter (DREAM), backing up the ECAL during beam tests, show that it is possible to estimate the independent contributions of scintillation and Čerenkov light. This information makes it possible to account for one of the dominant sources of fluctuations in hadronic showers and thus to achieve a significant improvement in hadronic calorimetry performance.
The production of single- and multi-photon events has been studied in the reaction e(+) e(-) --> gamma(gamma) + invisible particles. The data collected with the DELPHI detector during the years 1999 ...and 2000 at centre-of-mass energies between 191 GeV and 209 GeV was combined with earlier data to search for phenomena beyond the Standard Model. The measured number of light neutrino families was consistent with three and the absence of an excess of events beyond that predicted by the Standard Model processes was used to set limits on new physics. Both model-independent searches and searches for new processes predicted by supersymmetric and extra-dimensional models have been made. Limits on new non-standard model interactions between neutrinos and electrons were also determined.
A search for single top production (e(+)e(-) --> t (c) over bar) via flavour changing neutral currents (FCNC) was performed using the data taken by the DELPHI detector at LEP2. The data analyzed have ...been accumulated at center-of-mass energies ranging from 189 to 208 GeV. Limits at 95% confidence level were obtained on the anomalous coupling parameters kappa(gamma) and kappa(Z). (C) 2004 Published by Elsevier B.V.
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