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  • 1
    Electronic Resource
    Electronic Resource
    Monte Carlo integration to optimize geometry in gravitational experiments (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 3556-3563 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The torsion balance has been the experimental apparatus of choice for centuries, both in precision measurements of the Newtonian gravitational constant and in searches for weak anomalous interactions outside of gravity. If the form of the interaction is modeled, it is often possible to optimize the interacting bodies so that the apparatus has the greatest sensitivity to the interaction under study. Other researchers have applied this strategy in the case of the gravitational interaction between cylinders, and between a cylinder and sphere. Whereas their work focused on developing an analytical expression for the force between the masses, we present here a numerical method−Monte Carlo integration−which is general enough to aid in the design of bodies interacting under arbitrary potentials and with any desired geometric shape (as long as an accurate absolute value of the force is not needed). This numerical method is used to compute the gravitational torsion constant produced between an external hollow cylinder and sphere, and demonstrates the behavior studied previously through analysis. However, the main purpose for which we have used this numerical technique is in the design of interacting bodies used in a torsion-pendulum search for interactions that depend on net intrinsic spin. We demonstrate how the method may be used to determine the optimum aspect ratio (l/r) of the polarized test masses, as well as the most sensitive orientation of the masses. Two different interactions are considered: the dipole–dipole interaction between two polarized bodies, and the monopole–dipole interaction between a polarized and unpolarized body. In the case of the monopole–dipole interaction, we also show how the numerical method can indicate which orientation between test bodies is most susceptible to a false signal caused by gravity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1143764
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  • 2
    Electronic Resource
    Electronic Resource
    Imaging system to monitor the pendulum mode of a vibrationally driven torsion balance (1997)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 68 (1997), S. 4275-4281 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A digital-imaging system based on a personal computer was tested for its ability to track in real time periodic motion with a frequency near 1 Hz. When imaging a vibrationally isolated stationary target, the system displayed a limitation in positional measurement of 0.3×10−6 m. Further tests indicate that this limitation arises from environmental vibrations driving the target, even though it is mounted on a vibration-isolation table. This work demonstrates the feasibility of using digital imaging to measure motions other than the (usually very low frequency) torsion motion of a torsion balance, where the ultimate goal is to remove the effects of these motions from the torsion signal of interest. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1148385
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  • 3
    Electronic Resource
    Electronic Resource
    Measurement of small electrical forces using a torsion balance and capacitive position transducer (1986)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 57 (1986), S. 3019-3023 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A method for measuring the force arising from the attraction between a charged electrode and another electrode on which charges have been induced has been developed using a torsion balance operated in the ac mode far above the resonance frequency of the balance. The movement of the balance is sensed by a capacitive position transducer which uses two lock-in amplifiers to demodulate the position signal. The balance itself and the position transducer are described. The sensitivity of the position transducer is given, and results from three electrode geometries are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1138984
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  • 4
    Electronic Resource
    Electronic Resource
    The separation of small amounts of free fatty acids from large amounts of neutral fats on Sephadex LH-20
    Amsterdam : Elsevier
    Journal of Chromatography A 70 (1972), S. 164-167 
    Details
    ISSN: 0021-9673
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/S0021-9673(01)91073-8
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  • 5
    Electronic Resource
    Electronic Resource
    Gas-liquid chromatographic analysis of cardiolipin from fetal and maternal liver of the rat
    Amsterdam : Elsevier
    Biochimica et Biophysica Acta (BBA)/Lipids and Lipid Metabolism 231 (1971), S. 535-536 
    Details
    ISSN: 0005-2760
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology , Medicine , Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0005-2760(71)90122-6
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  • 6
    Electronic Resource
    Electronic Resource
    The visceral yolk sac - an important site of synthesis and secretion of apolipoprotein B containing lipoproteins in the feto-placental unit of the rat
    Amsterdam : Elsevier
    Biochimica et Biophysica Acta (BBA)/Lipids and Lipid Metabolism 1127 (1992), S. 174-185 
    Details
    ISSN: 0005-2760
    Keywords: (Rat yolk sac) ; Apolipoprotein B ; Lipoprotein ; Mathematical model ; Perinatal period
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology , Medicine , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/0005-2760(92)90275-Z
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  • 7
    Electronic Resource
    Electronic Resource
    Sulphur-containing “perfumes” attract flower-visiting bats (2000)
    Springer
    Journal of comparative physiology 186 (2000), S. 143-153 
    Details
    ISSN: 1432-1351
    Keywords: Key words Bat pollination ; Olfactory orientation ; Floral scents ; Sulphur compounds ; Dimethyl disulphide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  We tested the attractiveness of individual scent compounds of bat-pollinated flowers to their pollinators, small flower-visiting bats of the genus Glossophaga (Phyllostomidae). Twenty compounds belonging to four different chemical substance classes were tested, both in the laboratory and in the field. In the laboratory, the bats (Glossophaga soricina) approached odour sources spontaneously and without preceding experience. Without ever receiving any reward they preferred the scent of a sulphur-containing compound, dimethyl disulphide, to several other odour components emitted by bat-pollinated flowers, and to scentless controls. In the field, at La Selva station in the tropical lowland rain forest of Costa Rica, G. commissarisi were attracted by two sulphur-containing compounds, dimethyl disulphide and 2,4-dithiapentane, to visit artificial flowers filled with sugar water. Thus, in nectarivorous bats the sense of smell obviously plays an important role in searching for and localising food sources, and even single components of the scent bouquets of bat-pollinated flowers are attractive. The preference for sulphur-containing odours seems to be innate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003590050014
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  • 8
    Electronic Resource
    Electronic Resource
    Die Aktivität der Phosphatidase A und der Lysophosphatidase in Placenta, mütterlicher und foetaler Leber bei trächtigen Ratten (1964)
    Springer
    Naturwissenschaften 51 (1964), S. 340-340 
    Details
    ISSN: 1432-1904
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Natural Sciences in General
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00625087
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  • 9
    Electronic Resource
    Electronic Resource
    Synthesis, secretion and immunoelectron microscopic demonstration of apolipoprotein B-containing lipoprotein particles in the visceral rat yolk sac (1992)
    Springer
    Histochemistry and cell biology 97 (1992), S. 283-292 
    Details
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Electron microscopic investigations on the involvement of the fetal membranes of the rat (visceral yolk sac) in the lipid metabolism revealed the occurrence of lipoprotein-sized particles located in cisternal Golgi stacks, Golgi vesicles and secretory vesicles of the cells of the visceral yolk sac epithelium as well as in distended areas of the intercellular space between adjacent epithelial cells. Application of the protein A-gold technique with specific anti-apoB antiserum resulted in a specific location of immunogold both over the different compartments of the lipoprotein pathway (RER, Golgi complex, secretory vesicles) as well as over the distended intercellular spaces, thus confirming these particles to be lipoproteins in nature. Isolated visceral epithelial cells prepared by a tryptic digestion method exhibited some ultrastructural alterations, such as a loss of apical brush border, a change from columnar to spherical cell shape, a decrease in phagolysosomes, but an increase in autophagosomal structures after 6 h incubation at a vitality rate of at least 85%. Within this period the epithelial cells secreted measurable amounts of apoB-containing lipoproteins into the medium floating in the density classes d〈1.006 g/ml, d=1.006–1.020 g/ml and d=1.020–1.064 g/ml. The production of the lipoproteins was partly inhibited by cycloheximide indicating the secretion of particles with preformed as well as newly synthesized apoB. Negative staining of the particles revealed an average diameter of 34 nm of VLDL, 31 nm of IDL and 24 nm of LDL. In summary, our studies demonstrate that in the feto-placental unit of the rat the fetal membranes are capable of synthesizing and secreting lipoproteins. The cells of the visceral yolk sac epithelium were shown to be the producers of apoB-containing particles.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00267640
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  • 10
    Electronic Resource
    Electronic Resource
    Thermal conductivity and thermal Hall effect in Bi- and Y-based high-T c superconductors (2001)
    Springer
    The European physical journal 20 (2001), S. 189-208 
    Details
    ISSN: 1434-6036
    Keywords: PACS. 74.72.-h High Tc compounds – 74.25.Fy Transport properties (electric and thermal conductivity, thermoelectric effects, etc.)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract: Measurements of the thermal conductivity (kxx) and the thermal Hall effect (kxy) in high magnetic fields in Y- and Bi-based high-T c superconductors are presented. We describe the experimental technique and test measurements on a simple metal (niobium). In the high-T c superconductors kxx and kxy increase below T c and show a maximum in their temperature dependence. kxx has contributions from phonons and quasiparticle (QP) excitations, whereas kxy is purely electronic. The strong increase of kxy below T c gives direct evidence for a strong enhancement of the QP contribution to the heat current and thus for a strong increase of the QP mean free path. Using kxy and the magnetic field dependence of kxx we separate the electronic thermal conductivity ( k xx el ) of the CuO 2 -planes from the phononic thermal conductivity ( k xx ph ). In YBa2Cu3O 7 - δ k xx el shows a pronounced maximum in the superconducting state. This maximum is much weaker in Bi2Sr2CaCu2O 8 + δ , due to stronger impurity scattering. The maximum of k xx el is strongly suppressed by a magnetic field, which we attribute to the scattering of QPs on vortices. An additional magnetic field independent contribution to the maximum of kxx occurs in YBa2Cu3O 7 - δ , reminiscent of the contribution of the CuO-chains, as determined from the anisotropy in untwined single crystals. Our data analysis reveals that below T c as in the normal state a transport (τ) and a Hall ( ) relaxation time must be distinguished: The inelastic (i.e. temperature dependent) contribution to τ is strongly enhanced in the superconducting state, whereas displays the same temperature dependence as above T c . We determine also the electronic thermal conductivity in the normal state from kxy and the electrical Hall angle. It shows an unusual linear increase with temperature.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00011098
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