3,577 research outputs found
Bichromatic Local Oscillator for Detection of Two-Mode Squeezed States of Light
We present a new technique for the detection of two-mode squeezed states of
light that allows for a simple characterization of these quantum states. The
usual detection scheme, based on heterodyne measurements, requires the use of a
local oscillator with a frequency equal to the mean of the frequencies of the
two modes of the squeezed field. As a result, unless the two modes are close in
frequency, a high-frequency shot-noise-limited detection system is needed. We
propose the use of a bichromatic field as the local oscillator in the
heterodyne measurements. By the proper selection of the frequencies of the
bichromatic field, it is possible to arbitrarily select the frequency around
which the squeezing information is located, thus making it possible to use a
low-bandwidth detection system and to move away from any excess noise present
in the system.Comment: 11 pages, 3 figure
Structural and spectropotentiometric analysis of Blastochloris viridis heterodimer mutant reaction center
Heterodimer mutant reaction centers (RCs) of Blastochloris viridis were crystallized using microďŹuidic
technology. In this mutant, a leucine residue replaced the histidine residue which had acted as a ďŹfth ligand
to the bacteriochlorophyll (BChl) of the primary electron donor dimer M site (HisM200). With the loss of the
histidine-coordinated Mg, one bacteriochlorophyll of the special pair was converted into a bacteriopheophytin (BPhe), and the primary donor became a heterodimer supermolecule. The crystals had dimensions
400 Ă 100 Ă100 Îźm, belonged to space group P43212, and were isomorphous to the ones reported earlier for
the wild type (WT) strain. The structure was solved to a 2.5 Ă
resolution limit. Electron-density maps
conďŹrmed the replacement of the histidine residue and the absence of Mg. Structural changes in the
heterodimer mutant RC relative to the WT included the absence of the water molecule that is typically
positioned between the M side of the primary donor and the accessory BChl, a slight shift in the position of
amino acids surrounding the site of the mutation, and the rotation of the M194 phenylalanine. The
cytochrome subunit was anchored similarly as in the WT and had no detectable changes in its overall
position. The highly conserved tyrosine L162, located between the primary donor and the highest potential
heme C380, revealed only a minor deviation of its hydroxyl group. Concomitantly to modiďŹcation of the BChl
molecule, the redox potential of the heterodimer primary donor increased relative to that of the WT
organism (772 mV vs. 517 mV). The availability of this heterodimer mutant and its crystal structure provides
opportunities for investigating changes in light-induced electron transfer that reďŹect differences in redox
cascades
A Note on Flux Induced Superpotentials in String Theory
Non-vanishing fluxes in M-theory and string theory compactifications induce a
superpotential in the lower dimensional theory. Gukov has conjectured the
explicit form of this superpotential. We check this conjecture for the
heterotic string compactified on a Calabi-Yau three-fold as well as for warped
M-theory compactifications on Spin(7) holonomy manifolds, by performing a
Kaluza-Klein reduction.Comment: 19 pages, no figure
The Lantern Vol. 53, No. 2, Spring 1987
⢠The One ⢠Homecoming-1946 ⢠Puff ⢠Victory ⢠The Prelude ⢠Playtime ⢠There\u27s a Killer in My Heart ⢠Who is Keats? ⢠Relationships ⢠It\u27s OK ⢠Rasping ⢠Wearers of Underwear ⢠Conjecture ⢠Look Her in the Eye ⢠Counterpoint ⢠When the Air is Biting ⢠A Stream of Consciousness ⢠Bach\u27s Concerto in E ⢠Tomorrow Morn ⢠Ruminations on Bob Dylan ⢠Last Night a Dream ⢠Stephen ⢠A Baseball Story ⢠I Am Sorry ⢠And Baby Makes Two ⢠Next on Mr. Steinbeck\u27s Itinerary ⢠Upon Visiting the Nursing Home ⢠Taps for Ralph ⢠Yes, I Believe ⢠The Morning After ⢠Conversation ⢠Dear Man ⢠Autumn Leaveshttps://digitalcommons.ursinus.edu/lantern/1130/thumbnail.jp
A magnetically-driven piston pump for ultra-clean applications
A magnetically driven piston pump for xenon gas recirculation is presented.
The pump is designed to satisfy extreme purity and containment requirements, as
is appropriate for the recirculation of isotopically enriched xenon through the
purification system and large liquid xenon TPC of EXO-200. The pump, using
sprung polymer gaskets, is capable of pumping more than 16 standard liters per
minute (SLPM) of xenon gas with 750 torr differential pressure.Comment: 6 pages, 5 figure
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