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E Fischbach

Publications and source records attributed to E Fischbach.

At least 19 recordsLinked to original sources

Comment on "temperature dependence of the Casimir effect".

Recently, Brevik [Phys. Rev. E, 71, 056101 (2005)] adduced arguments against the traditional approach to the thermal Casimir force between real metals and in favor of one of the alternative approaches. The latter assume zero contribution from the transverse electric mode at zero frequency in qualitative disagreement with unity as given by the thermal quantum field theory for ideal metals. Those authors claim that their approach is consistent with experiments as well as with thermodynamics. We demonstrate that these conclusions are incorrect. We show specifically that their results are contradicted by four recent experiments and also violate the third law of thermodynamics (the Nernst heat theorem).

Comment↗

Measurement of the Casimir force between dissimilar metals.

The first precise measurement of the Casimir force between dissimilar metals is reported. The attractive force, between a Cu layer evaporated on a microelectromechanical torsional oscillator and an Au layer deposited on an Al2O3 sphere, was measured dynamically with a noise level of 6 fN/sqrt[Hz]. Measurements were performed for separations in the 0.2-2 micro m range. The results agree to better than 1% in the 0.2-0.5 micro m range with a theoretical model that takes into account the finite conductivity and roughness of the two metals. The observed discrepancies, which are much larger than the experimental precision, can be attributed to a lack of a complete characterization of the optical properties of the specific samples used in the experiment.

Journal Article↗

New experimental limits on strongly interacting massive particles at the TeV scale.

We have carried out a search for strongly interacting massive particles (SIMPs) bound to Au and Fe nuclei, which could manifest themselves as anomalously heavy isotopes of these elements. Our samples included gold from the NASA Long Duration Exposure Facility satellite, RHIC at Brookhaven National Laboratory, and from various geological sources. We find no evidence for SIMPs in any of our samples, and our results set stringent limits (as low as approximately 10(-12)) on the abundances of anomalous Au or Fe isotopes with masses up to 1.67 and 0.65 TeV/c(2), respectively.

Journal Article↗

Deflection of spacecraft trajectories as a new test of general relativity.

We derive a simple formula which gives the general relativistic deflection of a spacecraft, idealized as a point mass, for all values of the asymptotic speed V(infinity) (0< or =V(infinity)< or =1). Using this formula we suggest a new test of general relativity (GR) which can be carried out during a proposed interstellar mission that involves a close pass of the Sun. We show that, with foreseeable improvements in spacecraft tracking sensitivity, the deflection of a spacecraft's trajectory in the gravitational field of the Sun could provide a new test of GR.

Gravitation↗

New experimental test of the pauli exclusion principle using accelerator mass spectrometry

We report the results of a new experimental search for the Pauli-forbidden 1s(4) state of Be, denoted by Be ('). Using the Accelerator Mass Spectrometer facility at Purdue University, we set limits on the abundance of Be (') in metallic Be, Be ore, natural gas, and air. Our results improve on those obtained in a previous search for Be (') by a factor of approximately 300.

Journal Article↗

Purification and characterization of two different thymidine-5'-triphosphosphate-hydrolysing enzymes in human serum.

Two different enzymes capable of hydrolysing dTTP to the corresponding diphosphate were purified from human serum in order to investigate their enzymatic properties. A specific dTTPase was purified to apparent homogeneity with a purification factor of ca. 10,000 and showed a molecular mass of 46,000 Da, consisting of two identical subunits. This enzyme revealed an isoelectric point of 5.8 and a Km value of 38 microM. The other enzyme showed substrate specificity for dTTP and dCTP and was purified with a factor of ca. 5,000. It seems to be a multifunctional enzyme of one subunit (96,000 Da) with two different catalytic sites for dTTP and dCTP. The isoelectric point was 5.2, the Km values were 20 microM for dTTP and 17 microM for dCTP, respectively. Both enzymes were sensitive to inorganic phosphate, but the dTTPase to a minor extent. In contrast to the dCTPase-dTTPase, the dTTPase was strongly inhibited by ZnSO4. Physico-chemical and biochemical data suggest the purification of two different enzymes.

Chromatography, Liquid↗