Keck system

The assumptions of transition state theory allow for the derivation of a kinetic rate constant from equilibrium properties of the system. That seems almost too good to be true. In fact, it sometimes is [8,18-21]. Violations of the assumptions of TST do occur. In those cases, a more detailed description of the system dynamics is necessary for the accurate estimate of the kinetic rate constant. Keck [22] first demonstrated how molecular dynamics could be combined with transition state theory to evaluate the reaction rate constant (see also Ref. 17). In this section, an attempt is made to explain the essence of these dynamic corrections to TST. 

Another indicator of the performance of AO systems is the number of refereed publications per year based on observations made using AO. This has been rising steadily over the last decade and is now >30 per year (see http //www2.keck.hawaii.edu 3636/realpublic/inst/ao/ao sciJist.html). 

W.M. Keck Observatory. A LGS system similar to the Lick Observatory design has been commissioned at the Keck Observatory (see Section 14.4.3.4). 

A Systems Design Example The Keck Laser Guide Star. 

System Design. For the Keck AO, LGS requirements are 0.3 ph/cm /ms for the return flux and 0.6 arcsec for the spot diameter. The resulting laser system specifications are given in Table 2. The repetition rate was increased by a factor of 2 relative to the Lick system to improve the sodium return. 

Figure 18. Layout of the pulsed dye laser guide star system at the Keck observatory.

The pump lasers were designed and built at LLNL. Two laser cavity configurations are employed. Two "L" shaped cavities run at the full system repetition rate of 26 kHz, producing 40-50 W per laser. They pump the DM0 and preamplifier dye cells. Four "Z" cavity lasers run at 13 kHz, each producing between 60-80 W. They are interleaved in the power amplifier dye cell to produce an effective 26 kHz repetition rate. Flashlamps were used to pump the frequency-doubled YAG lasers as diode-pumps were much more expensive at the time the Keck LGS was designed. In addition, high wavefront quality is not required... 

Under 1 arcsec seeing, the LGS FWHM was 1.4 arcsec. Images taken with the Keck primary mirror defocused (Fig. 24) demonstrated the level of distortion expected for an off-axis projection system. Low-level scattering was also minimal, consistent with expectations and seeing conditions. 

LGS/AO System Integration. A number of modifications have been implemented in the Keck II AO system to accommodate LGS/AO (Contos et al., 2002) a tip-tilt sensor to provide NGS- based tip-tilt, a low bandwidth WFS (LBWFS) to measure long term focus using a NGS, focus tracking for the high bandwidth WFS (HBWFS) looking at the LGS, and a tip-tilt control loop for the laser pointing. 

On September 20, 2003, all subsystems finally came together to reveal the unique capability of the Keck LGS/AO system. The system locked on HK Tau, a 15 magnitude well-known T Tauri binary, revealing details of the cir-cumstellar disk of its companion (Fig. 25). This was the first demonstration of a LGS/AO system on a large telescope. The FWHM is 50 milli-arcsec, compared to 183 milli- arcsec for the uncorrected image. While locked on a 14 magnitude star, the LGS/AO system recorded Strehls 0.36 (at 2.1/rm), 30-sec exposure time, compared to 0.04 for uncorrected images. 

Of the above Na LGS/AO systems, only 4 have obtained sharpened images, namely those at Lick, MMT, Calar Alto and most recently Keck. They show that the technology is available today to deploy LGSs, but a substantial amount... 

Figure 25. First light image of the Keck LGS AO system. The lens-like nebula at upper left is a disk of dust and gas surrounding the young star HK Tau B, The star is hidden from direct view, seen only in light reflected off the upper and lower surfaces of the disk.

Keck, J. C. (1978). Rate-controlled constrained equilibrium method for treating reactions in complex systems. In Maximum Entropy Formalism" (R. D. Levine and M. Tribus, eds). M.I.T. Press, Cambridge, MA. 

Compound (Miles Laboratories, Elkhart, IN), snap-frozen, and cut into sections for comparison with paraffin-embedded cell sections (3) FFPE Cell Blocks Six cell pellets were fixed in 10% neutral buffered formalin immediately after harvest, at room temperature for 6,12,24h, 3,7, and 30 days, respectively. For further comparison with the cell model system, recently collected sample of human breast cancer tissues were processed by OCT-embedding and snap-freezing the corresponding routine FFPE block that was obtained from the Norris Cancer Hospital and Research Institute at the University of Southern California Keck School of Medicine (USC). This tissue block was processed routinely (formalin-fixed 24h and processed by automatic equipment). 

Kudlich M, Keck A, Klein J, Stolz A (1997) Localization of the enzyme system involved in anaerobic reduction of azo dyes by Sphingomonas sp. strain BN6 and effect of artificial redox mediators on the rate of azo dye reduction. Appl Env Microbiol 63 3691-3694... 

Taking into account the central role of the HPA-axis for the regulation of anxiety, a variety of genetically altered mice has been developed, aimed at targeting the hormonal stress system (Muller and Keck 2002 Sillaber et al. 2002 Stenzel-Poore et al. 1992 Timpl et al. 1998). These models are described extensively in the chapter by Keck and Muller and will, therefore, be omitted here. 

M iiller MB, Landgraf R, SiUaber I, Kresse AE, Keck ME, Zimmermann S, Holsboer F, Wurst W (2000) Selective activation of the hypothalamic vasopressin ergic system in mice deficient for the corticotropin-releasing hormone receptor 1 is dependent on glucocorticoids. Endocrinology 141 4262-4269... 

Keck ME, Holsboer F (2001) Hyperactivity of CRH neiu-onal circuits as a target for therapeutic interventions in affective disorders. Peptides 22 835-844 Kellner M, Wiedemann K, Holsboer F (1992) ANF inhibits the CRH-stimulated secretion of ACTH and cortisol in man. Life Sci 50 1835-1842 Kellner M, Herzog L, Yassouridis A, Holsboer F, Wiedemann K (1995) A possible role of atrial natriuretic hormone in pituitary-adrenocortical imresponsiveness in lactate-induced panic disorder. Am J Psychiatry 152 1365-1367 Kennedy JL, Bradwein J, Koszycki D (1999) Investigation of cholecystokinin system genes in panic disorder. Mol Psychiatry 4 284-285... 

Keck Observatory on Mauna Kea, ffawaii, installs an adaptive optics system. 

Regarding the 5-HT system, Keck et al. (286) cite several lines of evidence to support that the thymolytic effects of clozapine (and perhaps other agents with similar properties) are mediated by the antagonism of 5-HT2 receptors, including the following ... 

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