618 research outputs found
Challenging the paradigms of gut architecture and feeding biomechanics in shallow water polychaetes
No full textFor well over a century a great deal of effort has been expended into investigation of how polychaetes capture their food but there has been a relative lack of attention paid to the processing of ingested material in the various forms and functioning of the anterior gut in errant polychaetes. The principal focus of this study was the examination of the functional anatomy of the anterior digestive tracts from three families of polychaetes; the Arenicolidae; sedentary detritivores, the Nereidae; errant omnivores and the Nephtyidae; errant carnivores. Comparisons were made with the already well-studied gut anatomy and particularly the pharyngeal anatomy of Arenicola marina, so as to establish a baseline for the other families of polychaetes.Particular attention was focused on the method of pharyngeal stabilisation in relation to food capture and processing.It is universally accepted that ‘coelomic pressure’ has been the primary factor in the eversion of the pharynx and proboscis in polychaete worms. This study challenges this hypothesis. This was done with the use of micro-dissection in anaesthetised polychaetes, electro-stimulation, modern light microscopy methods and novel application of micro-computed x-ray tomography. Investigations using scanningelectron microscopy with freeze dried and freeze fractured specimens have revealed a very unusual interlacing muscle fibre pattern, in the Nephtys pharynx. This suggests that specialised pharyngeal muscles, and particularly a newly named muscle, the ventral coelomic muscle (VCM), in Nephtys, may be a primary mover of proboscis eversion rather than as a consequence of an increase in coelomicpressure. To date, only one other study has recognised this muscle, describing it as a ‘ventral retensor’ that possibly aided in the retraction of the extruded pharynx. The VCM has its origin in the ventral pharynx; it is connected to the anterior intestine, and inserted into the ventral body wall from segment 40-45. This, at least, suggests a stabilising muscle for the pharynx and proximal intestine. The present study’s observations suggest that this muscle is in fact a major player in a primarily muscular driving force for proboscis extrusion. These findings strongly suggest that coelomic pressure increases, associated with proboscis extrusion, are secondary factors in proboscis extrusion in the Nephtyidae. In the Nereidae, it would appear, that the combined action of the powerful longitudinal and circular muscles, together with the firm integrity of the outer body wall, are important players in the muscular extrusion of the pharynx and jaws. Associated increases in coelomic pressure are possibly a secondary effect and linked more with burrowing and body movementand hydrostatic support.In errant polychaetes with relatively short straight guts the anterior sections of the gut should be expected to play an important role in food processing, especially as examination of the intestines of many species, especially Nephtyidae, have revealed many of them to be empty
Virtual Institute for Spin and Strong QCD
No full textThe Virtual Institue on Spin-physics and strong QCD is composed by 7 European Universities and Research Institutes (from Germany, Italy, Switzerland and Paoland). The Institute has the goal of supporting research in the field of hadron physics favouring exchange of you physicists and scientific collaboration between the involved institutes
Simvastatin preserves the structure of coronary adventitial vasa vasorum in experimental hypercholesterolemia independent of lipid lowering
No full textNew structures in sound, November 30, 1973
No full textRecorded during a live performance at Oakland Recital Hall, Western Michigan University, Kalamazoo, Michigan, November 30, 1973, program no. 81 of the Department of Music’s 1973-1974 season.Various performers.2nd work sung in English.Information from performance program.Reel 1: Seven pieces for woodwind [i.e. wind] quintet / Gyorgy Ligeti (Charles Osborne, flute ; Robert Humiston, oboe ; Daniel Kyser, clarinet ; William Allgood, bassoon ; Neill Sanders, French horn) -- (13:28) Voices: a multi-sound piece for amplified soprano and four-channel magnetic tape (1972) / Ramon Zupko (Joyce Zostrow, soprano) -- (27:37) Violin sonata no. 2 / Charles Ives (Gerald Fischbach, violin ; Phyllis Rappeport, piano).Reel 2: Ordres (1973) / C. Curtis-Smith -- (15:49) Fugue and white numbers (1973) / Robert Ritman (Joe Narkewitz, video ; Robert Ritman, magnetic tape) -- (22:00) Octandre / Edgard Varese (Ed Sabrack, flute ; Gayle Petrick, oboe ; Tim Riley, clarinet ; Chip King, bassoon ; Cary Belcher, trumpet ; John Dickey, trombone ; Ingrid Felt, French horn ; Bill Ritchie, double bass).Reel 3: Speedball / Lee Morgan ; (8:18) U.B. / Bob Ricci ; (17:20) Killer Joe / Benny Golson (Bob Ricci, piano ; Tom Shirah, trumpet ; Bill Kennedy, Trent Kynaston, saxophones ; Ron Harvill, double bass ; Scott Bradley, percussion)
The PANDA Detector at the GSI-FAIR Project
No full textA major component of the approved upgrade of the GSI facility in Darmstadt, Germany is the High Energy Storage Ring (HESR) for high intensity, phase space cooled antiprotons with momenta up to 15 GeV/c. At this facility a wide physics program is planned to investigate both the structure of hadrons in the charmonium mass range and the spectroscopy of double hypernuclei. To serve the many experiments planned at this new facility, a general purpose detector called PANDA (Proton ANtiproton Detector Array) is planned. An overview of the PANDA detector concept, as well as selected results from simulation of the detector's performance will be presented
Particle identification using the time-over-threshold measurements in straw tube detectors
No full textThe identification of charged particles based on energy losses in straw tube detectors has been simulated. The response of a new front-end chip developed for the PANDA straw tube tracker was implemented in the simulations and corrections for track distance to sense wire were included. Separation power for p-K, p-@p and K-@p pairs obtained using the time-over-threshold technique was compared with the one based on the measurement of collected charge
A sampling ADC as a universal tool for data processing and trigger application
No full textFor the particle identification via energy loss measurement and algorithm tests for the PANDA Straw Tube Tracker (STT), a new dedicated FPGA firmware for the 16 channel 240 MHz sampling ADC has been developed. New FPGA firmware can simultaneously deliver charge, amplitude and time informations which are extracted from the detector signals. It also provide the possibilities to record raw signal information in an intelligent oscilloscope mode. The sampling ADC with the new FPGA firmware has scaler capabilities and can be used for self triggering and as a coincidence unit
Application of straw detector for particle identification - Feasibility studies with PANDA STT prototype
No full textIn the PANDA experiment at the HESR antiproton storage ring of the FAIR facility in Darmstadt (Germany) the central tracker is a key element which will provide information about decay vertices, momenta and the type of charged particle emitted in antiproton annihilation. Various techniques are known for the extraction of energy-loss information from analog signals of gaseous detectors like straw chambers. These include electronical techniques as well as off-line treatment of the data. The main difficulty lies in the poor statistics of the formation of electron-ion clusters and in the strong asymmetry of the Landau distribution. A general-purpose chain of electronics and data acquisition based on sampling ADCs has been developed which permits off-line application of various techniques
Experimental results of the dE/dx resolution measurement in PANDA-type Straw Tube Tracker
No full textStraw tubes are known as excellent tools for particle tracking. A multilayer, densely packed ensemble of about 5000 straw tubes - so called Straw Tube Trackers (STT) is considered as an option for the central tracker of the future PANDA@FAIR experiment. Simulations indicate that the energy loss of particles traversing several layers of straw tubes can in addition result in a decisive contribution to particle discrimination in the momentum range up to 1.5 GeV/c. Experimental investigation of the energy resolution in prototype of the PANDA-type STT have been undertaken in Research Center Jülich (Germany). The experimental setup, readout electronics, method of data treatment and the encouraging results are presented
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