1,155 research outputs found
Ultrasonic Doppler measurement of renal artery blood flow
An extensive evaluation of the practical and theoretical limitations encountered in the use of totally implantable CW Doppler flowmeters is provided. Theoretical analyses, computer models, in-vitro and in-vivo calibration studies describe the sources and magnitudes of potential errors in the measurement of blood flow through the renal artery, as well as larger vessels in the circulatory system. The evaluation of new flowmeter/transducer systems and their use in physiological investigations is reported
Ultrasonic Doppler measurement of renal artery blood flow
Studies were made of (1) blood flow redistribution during lower body negative pressure (LBNP), (2) the profile of blood flow across the mitral annulus of the heart (both perpendicular and parallel to the commissures), (3) testing and evaluation of a number of pulsed Doppler systems, (4) acute calibration of perivascular Doppler transducers, (5) redesign of the mitral flow transducers to improve reliability and ease of construction, and (6) a frequency offset generator designed for use in distinguishing forward and reverse components of blood flow by producing frequencies above and below the offset frequency. Finally methodology was developed and initial results were obtained from a computer analysis of time-varying Doppler spectra
Finite-temperature magnetism of FePd and CoPt alloys
The finite-temperature magnetic properties of FePd and
CoPt alloys have been investigated. It is shown that the
temperature-dependent magnetic behaviour of alloys, composed of originally
magnetic and non-magnetic elements, cannot be described properly unless the
coupling between magnetic moments at magnetic atoms (Fe,Co) mediated through
the interactions with induced magnetic moments of non-magnetic atoms (Pd,Pt) is
included. A scheme for the calculation of the Curie temperature () for
this type of systems is presented which is based on the extended Heisenberg
Hamiltonian with the appropriate exchange parameters obtained from
{\em ab-initio} electronic structure calculations. Within the present study the
KKR Green's function method has been used to calculate the parameters.
A comparison of the obtained Curie temperatures for FePd and
CoPt alloys with experimental data shows rather good agreement.Comment: 10 pages, 12 figure
Optical Scattering Lengths in Large Liquid-Scintillator Neutrino Detectors
For liquid-scintillator neutrino detectors of kiloton scale, the transparency
of the organic solvent is of central importance. The present paper reports on
laboratory measurements of the optical scattering lengths of the organic
solvents PXE, LAB, and Dodecane which are under discussion for next-generation
experiments like SNO+, Hanohano, or LENA. Results comprise the wavelength range
from 415 to 440nm. The contributions from Rayleigh and Mie scattering as well
as from absorption/re-emission processes are discussed. Based on the present
results, LAB seems to be the preferred solvent for a large-volume detector.Comment: 9 pages, 3 figures, accepted for publication by Rev. Scient. Instr
Analyses and localization of pectin-like carbohydrates in cell wall and mucilage of the green alga Netrium digitus
The unicellular, simply shaped desmid Netrium digitus inhabiting acid bog ponds grows in two phases. Prior to division, the cell elongates at its central zone, whereas in a second phase, polar tip growth occurs. Electron microscopy demonstrates that Netrium is surrounded by a morphologically homogeneous cell wall, which lacks pores. Immunocytochemical and biochemical analyses give insight into physical wall properties and, thus, into adaptation to the extreme environment. The monoclonal antibodies JIM5 and JIM7 directed against pectic epitopes with different degrees of esterification label preferentially growing wall zones in Netrium. In contrast, 2F4 marks the cell wall only after experimental de-esterification. Electron energy loss spectroscopy reveals Ca-binding capacities of pectins and gives indirect evidence for the degree of their esterification. An antibody raised against Netrium mucilage is not only specific to mucilage but also recognizes wall components in transmission electron microscopy and dot blots. These results indicate a smooth transition between mucilage and the cell wall in Netrium
Extrovert Followership and its Impact on Agreeable Leadership
This study recons the need for research on effective role of followership in mentoring a leader to set pattern or direction for leader. A reinvented concept of leader being a team man needs active participation from followers in changing business dynamics. The sample consisting of middle level management having leader (heads/ supervisors from education sector) above it has been taken and results are achieved using inferential statistics, so to verify the need of followers for result oriented leadership. The results depict that certain personality traits backed by âBig Five Modelâ are found to be important for followers to have an impact on leaderâs decision making. As this study analyses the mutual characteristic of leader follower relation statistically while putting follower on the fore front, the originality of study is ensured. As for limitation, this study may show different results as per variant geographical and economical regions in which followersâ expectations may vary accordingly
Muon and Cosmogenic Neutron Detection in Borexino
Borexino, a liquid scintillator detector at LNGS, is designed for the
detection of neutrinos and antineutrinos from the Sun, supernovae, nuclear
reactors, and the Earth. The feeble nature of these signals requires a strong
suppression of backgrounds below a few MeV. Very low intrinsic radiogenic
contamination of all detector components needs to be accompanied by the
efficient identification of muons and of muon-induced backgrounds. Muons
produce unstable nuclei by spallation processes along their trajectory through
the detector whose decays can mimic the expected signals; for isotopes with
half-lives longer than a few seconds, the dead time induced by a muon-related
veto becomes unacceptably long, unless its application can be restricted to a
sub-volume along the muon track. Consequently, not only the identification of
muons with very high efficiency but also a precise reconstruction of their
tracks is of primary importance for the physics program of the experiment. The
Borexino inner detector is surrounded by an outer water-Cherenkov detector that
plays a fundamental role in accomplishing this task. The detector design
principles and their implementation are described. The strategies adopted to
identify muons are reviewed and their efficiency is evaluated. The overall muon
veto efficiency is found to be 99.992% or better. Ad-hoc track reconstruction
algorithms developed are presented. Their performance is tested against muon
events of known direction such as those from the CNGS neutrino beam, test
tracks available from a dedicated External Muon Tracker and cosmic muons whose
angular distribution reflects the local overburden profile. The achieved
angular resolution is 3-5 deg and the lateral resolution is 35-50 cm, depending
on the impact parameter of the crossing muon. The methods implemented to
efficiently tag cosmogenic neutrons are also presented.Comment: 42 pages. 32 figures on 37 files. Uses JINST.cls. 1 auxiliary file
(defines.tex) with TEX macros. submitted to Journal of Instrumentatio
Muon and Cosmogenic Neutron Detection in Borexino
Borexino, a liquid scintillator detector at LNGS, is designed for the
detection of neutrinos and antineutrinos from the Sun, supernovae, nuclear
reactors, and the Earth. The feeble nature of these signals requires a strong
suppression of backgrounds below a few MeV. Very low intrinsic radiogenic
contamination of all detector components needs to be accompanied by the
efficient identification of muons and of muon-induced backgrounds. Muons
produce unstable nuclei by spallation processes along their trajectory through
the detector whose decays can mimic the expected signals; for isotopes with
half-lives longer than a few seconds, the dead time induced by a muon-related
veto becomes unacceptably long, unless its application can be restricted to a
sub-volume along the muon track. Consequently, not only the identification of
muons with very high efficiency but also a precise reconstruction of their
tracks is of primary importance for the physics program of the experiment. The
Borexino inner detector is surrounded by an outer water-Cherenkov detector that
plays a fundamental role in accomplishing this task. The detector design
principles and their implementation are described. The strategies adopted to
identify muons are reviewed and their efficiency is evaluated. The overall muon
veto efficiency is found to be 99.992% or better. Ad-hoc track reconstruction
algorithms developed are presented. Their performance is tested against muon
events of known direction such as those from the CNGS neutrino beam, test
tracks available from a dedicated External Muon Tracker and cosmic muons whose
angular distribution reflects the local overburden profile. The achieved
angular resolution is 3-5 deg and the lateral resolution is 35-50 cm, depending
on the impact parameter of the crossing muon. The methods implemented to
efficiently tag cosmogenic neutrons are also presented.Comment: 42 pages. 32 figures on 37 files. Uses JINST.cls. 1 auxiliary file
(defines.tex) with TEX macros. submitted to Journal of Instrumentatio
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