The particle tracking silicon microscope PTSM Sadrozinski, H.F.-W.; Bashkirov, V.; Bruzzi, M. ...
IEEE transactions on nuclear science,
2004-Oct., 2004-10-00, 20041001, Letnik:
51, Številka:
5
Journal Article
Recenzirano
Odprti dostop
A novel position- and energy-sensitive particle detector for radiobiological application is described. The aim is to support research in radiation response of biological systems, for example in the ...induction of mutations in C. elegans, where precise knowledge of location and intensity of the radiation is crucial to understand radiation sensitivity of individual cells. The "Particle Tracking Silicon Microscope" (PTSM) consists of a silicon strip detector in direct contact with radiobiological samples (e.g., C. elegans), such that the location and intensity of particle radiation can be controlled at the 10 /spl mu/m scale. The readout is performed with low-noise readout electronics, which allows the determination of the particle's position from the hit strip address and its energy from the specific energy loss. In our implementation, the energy loss is measured through the time-over-threshold (TOT). The noise rate at acceptable thresholds is so low that the single particles can be detected with 100% efficiency. The performance of the front-end ASIC is described, and the results of initial environmental tests are reported. These include placing biological samples and saline solutions in direct contact with the silicon detectors.
The BB detector: Upgrades, operation and performance Martinelli, M.; Zhu, Y.S.; Gill, M.S. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
11/2013, Letnik:
729, Številka:
C
Journal Article
BaBar silicon vertex tracker: Status and prospects Re, V.; Bondioli, M.; Bruinsma, M. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
12/2006, Letnik:
569, Številka:
1
Journal Article
Costea, M. (Department of Biology, Wilfrid Laurier University, ON, Canada, N2L 3C5; mcostea@wlu.ca), G. L. Nesom (Botanical Research Institute of Texas, 509 Pecan Street, Fort Worth, TX 76102-4060, ...U.S.A.; gnesom@brit.org) & F. J. Tardif (Department of Plant Agriculture, University of Guelph, Guelph, ON N1G 2W1, Canada; ftardif@uoguelph.ca). Taxonomic status of Cuscuta nevadensis and C. veatchii (Convolvulaceae) in North America. Brittonia 57: 264–272. 2005.—The taxonomy of Cuscuta nevadensis and C. veatchii is investigated. Cuscuta nevadensis is more closely related to C. veatchii and C. denticulata than to C. salina, and the former two taxa are accepted as species. A summary of relevant taxonomic and biological information is provided, including synonymy, distribution and ecology, keys, and a comparison of the morphology of flowers and seeds are examined. The morphological basis of vivipary in C. nevadensis is discussed. The status of Cuscuta vivipara, an invalid name in recent use, is clarified.
Myxamoebae of the cellular slime mold Dicytostelium discoideum aggregate in response to a chemotactic substance identified as adenosine 3′:5′-cyclic monophosphate. Upon aggregation cell division is ...suppressed, the cells become adhesive, and differentiation is initiated. Freeze-fracture studies of myxamoebae were conducted to determine the effect of cyclic AMP and calcium on plasma membrane ultrastructure. The inner surfaces of the plasma membranes exhibited particulate structures whose sizes (43-187 angstrom) and frequency distribution were determined. Cyclic AMP and calcium induced within 2 hr the formation of particles having average diameters 1.7-times and 1.5-times greater, respectively, than those of the vegetative myxamoebae controls. These data suggest that cyclic AMP mobilizes the intracellular calcium which may be effective in changing plasma membrane structure.
B a B ar silicon vertex tracker: Status and prospects Re, V.; Bondioli, M.; Bruinsma, M. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
2006, Letnik:
569, Številka:
1
Journal Article
Recenzirano
The
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ar Silicon Vertex Tracker (SVT) has been efficiently operated for six years since the start of data taking in 1999. Due to higher than expected background levels some unforeseen effects ...have appeared. We discuss: a shift in the pedestal for the channels of the AToM readout chips that are most exposed to radiation; an anomalous increase in the bias leakage current for the modules in the outer layers. Estimates of future radiation doses and occupancies are shown together with the extrapolated detector performance and lifetime, in light of the new observations.
Galax, a monotype endemic to the southern Appalachian Mountains and outlying areas, has been reported to comprise both a diploid and tetraploid cytotype (x = 6). In this study more than 850 ...chromosome counts of Galax urceolata from 460 locations, including numerous intra-populational counts, were made and mapped along with most of Baldwin's original counts in order to obtain a clear picture of the geographic distribution of the cytotypes. A strong correlation between guard cell size and chromosome number allowed estimation of ploidy level of herbarium collections. The diploid race occurs over most of the range of the species. Tetraploids occupy a relatively smaller portion of the range; they are abundant along the area of the Blue Ridge escarpment, sharply bounded on the northwest by the escarpment in northern North Carolina and by the Blue Ridge divide further south. On the Virginia coastal plain and north-central piedmont of North Carolina tetraploids occur exclusive of diploids. Along the escarpment diploids and tetraploids occur in complex patterns of sympatry and triploids are abundant, usually growing intermixed with or immediately adjacent to one of the other cytotypes. Along the escarpment there is much overlap in habitat preference, but commonly the more xeric habitats are occupied by diploids and the more mesic ones by tetraploids. No differences in habitat are apparent on the piedmont and coastal plain where the cytotypes are allopatric.
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