Investigation of possibilities for solar powered high energy lasers in space

The feasibility of solar powered high energy lasers in space has been studied. Preliminary analysis indicates that both direct and indirect pumping methods lead to high energy lasers having interesting efficiencies and capabilities. Many topics for further research have been identified

Previously Unidentified Changes in Renal Cell Carcinoma Gene Expression Identified by Parametric Analysis of Microarray Data

BACKGROUND. Renal cell carcinoma is a common malignancy that often presents as a metastatic-disease for which there are no effective treatments. To gain insights into the mechanism of renal cell carcinogenesis, a number of genome-wide expression profiling studies have been performed. Surprisingly, there is very poor agreement among these studies as to which genes are differentially regulated. To better understand this lack of agreement we profiled renal cell tumor gene expression using genome-wide microarrays (45,000 probe sets) and compare our analysis to previous microarray studies. METHODS. We hybridized total RNA isolated from renal cell tumors and adjacent normal tissue to Affymetrix U133A and U133B arrays. We removed samples with technical defects and removed probesets that failed to exhibit sequence-specific hybridization in any of the samples. We detected differential gene expression in the resulting dataset with parametric methods and identified keywords that are overrepresented in the differentially expressed genes with the Fisher-exact test. RESULTS. We identify 1,234 genes that are more than three-fold changed in renal tumors by t-test, 800 of which have not been previously reported to be altered in renal cell tumors. Of the only 37 genes that have been identified as being differentially expressed in three or more of five previous microarray studies of renal tumor gene expression, our analysis finds 33 of these genes (89%). A key to the sensitivity and power of our analysis is filtering out defective samples and genes that are not reliably detected. CONCLUSIONS. The widespread use of sample-wise voting schemes for detecting differential expression that do not control for false positives likely account for the poor overlap among previous studies. Among the many genes we identified using parametric methods that were not previously reported as being differentially expressed in renal cell tumors are several oncogenes and tumor suppressor genes that likely play important roles in renal cell carcinogenesis. This highlights the need for rigorous statistical approaches in microarray studies.National Institutes of Healt

Quantum limit of deterministic theories

We show that the quantum linear harmonic oscillator can be obtained in the large $N$ limit of a classical deterministic system with SU(1,1) dynamical symmetry. This is done in analogy with recent work by G.'t Hooft who investigated a deterministic system based on SU(2). Among the advantages of our model based on a non--compact group is the fact that the ground state energy is uniquely fixed by the choice of the representation.Comment: 4 pages, 2 figures, minor corrections added. To appear in the Proceedings of Waseda International Symposium on Fundamental Physics: "New Perspectives in Quantum Physics", 12-15 November 2002, Waseda University, Tokyo, Japa

Quantization, group contraction and zero point energy

We study algebraic structures underlying 't Hooft's construction relating classical systems with the quantum harmonic oscillator. The role of group contraction is discussed. We propose the use of SU(1,1) for two reasons: because of the isomorphism between its representation Hilbert space and that of the harmonic oscillator and because zero point energy is implied by the representation structure. Finally, we also comment on the relation between dissipation and quantization.Comment: 6 pages, 3 figure

Plasma Electronics

Contains reports on five research projects.National Science Foundation (Grant GK-19)Lincoln Laboratory (Purchase Order DDL BB-107)U. S. Air Force (Contract AF 19(628)-500)U. S. Atomic Energy Commission (Contract AT(30-1)-3221)U. S. Atomic Energy Commission (Contract AT(30-1)-3285

Pound-locking for characterization of superconducting microresonators

We present a new application and implementation of the so-called Pound locking technique for the interrogation of superconducting microresonators. We discuss how by comparing against stable frequency sources this technique can be used to characterize properties of resonators that can not be accessed using traditional methods. Specifically, by analyzing the noise spectra and the Allan deviation we obtain valuable information about the nature of the noise in superconducting planar resonators. This technique also greatly improves the read-out accuracy and measurement throughput compared to conventional methods.Comment: 5 page

Multiwavelength Observations of the Low Metallicity Blue Compact Dwarf Galaxy SBS 0335-052

New infrared and millimeter observations from Keck, Palomar, ISO, and OVRO and archival data from the NRAO VLA and IRAS are presented for the low metallicity blue compact dwarf galaxy SBS 0335-052. Mid-infrared imaging shows this young star-forming system is compact (0.31"; 80 pc) at 12.5 microns. The large Br-gamma equivalent width (235 Angstroms) measured from integral field spectroscopy is indicative of a ~5 Myr starburst. The central source appears to be optically thin in emission, containing both a warm (~80 K) and a hot (~210 K) dust component, and the overall interstellar radiation field is quite intense, about 10,000 times the intensity in the solar neighborhood. CO emission is not detected, though the galaxy shows an extremely high global H I gas-to-dust mass ratio, high even for blue compact dwarfs. Finally, the galaxy's mid-infrared-to-optical and mid-to-near-infrared luminosity ratios are quite high, whereas its far-infrared-to-radio and far-infrared-to-optical flux ratios are surprisingly similar to what is seen in normal star-forming galaxies. The relatively high bolometric infrared-to-radio ratio is more easily understood in the context of such a young system with negligible nonthermal radio continuum emission. These new lines of evidence may outline features common to primordial galaxies found at high redshift.Comment: 28 pages including 6 figures; accepted for publication in the Astronomical Journa

Interferometry with Photon-Subtracted Thermal Light

We propose and implement a quantum procedure for enhancing the sensitivity with which one can determine the phase shift experienced by a weak light beam possessing thermal statistics in passing through an interferometer. Our procedure entails subtracting exactly one (which can be generalized to m) photons from the light field exiting an interferometer containing a phase-shifting element in one of its arms. As a consequence of the process of photon subtraction, and somewhat surprisingly, the mean photon number and signal-to-noise ratio of the resulting light field are thereby increased, leading to enhanced interferometry. This method can be used to increase measurement sensitivity in a variety of practical applications, including that of forming the image of an object illuminated only by weak thermal light

Path Integrals in Polar Field Variables in QFT

We show how to transform a $d$-dimensional Euclidean path integral in terms of two (Cartesian) fields to a path integral in terms of polar field variables. First we present a conjecture that states how this transformation should be done. Then we show that this conjecture is correct in the case of two toy models. Finally the conjecture will be proven for a general QFT model with two fields

Quantum statistical properties of some new classes of intelligent states associated with special quantum systems

Based on the {\it nonlinear coherent states} method, a general and simple algebraic formalism for the construction of \textit{`$f$-deformed intelligent states'} has been introduced. The structure has the potentiality to apply to systems with a known discrete spectrum as well as the generalized coherent states with known nonlinearity function $f (n)$. As some physical appearance of the proposed formalism, a few new classes of intelligent states associated with \textit{`center of-mass motion of a trapped ion'}, \textit{`harmonious states'} and \textit{`hydrogen-like spectrum'} have been realized. Finally, the nonclassicality of the obtained states has been investigated. To achieve this purpose the quantum statistical properties using the Mandel parameter and the squeezing of the quadratures of the radiation field corresponding to the introduced states have been established numerically.Comment: 13page