Osteoclasts are specialized cells derived from the monocyte/macrophage haematopoietic lineage that develop and adhere to bone matrix, then secrete acid and lytic enzymes that degrade it in a specialized, extracellular compartment. Discovery of the RANK signalling pathway in the osteoclast has provided insight into the mechanisms of osteoclastogenesis and activation of bone resorption, and how hormonal signals impact bone structure and mass. Further study of this pathway is providing the molecular basis for developing therapeutics to treat osteoporosis and other diseases of bone loss.

Osteoclast differentiation and activation

Bevacizumab plus Irinotecan,Fluorouracil,and Leucovorin for Metastatic Colorectal Cancer

We describe the design, construction, and performance of the Sloan Digital Sky Survey telescope located at Apache Point Observatory. The telescope is a modified two-corrector Ritchey-Chretien design with a 2.5 m, f/2.25 primary, a 1.08 m secondary, a Gascoigne astigmatism corrector, and one of a pair of interchangeable highly aspheric correctors near the focal plane, one for imaging and the other for spectroscopy. The final focal ratio is f/5. The telescope is instrumented by a wide-area, multiband CCD camera and a pair of fiber-fed double spectrographs. Novel features of the telescope include the following: (1) A 3° diameter (0.65 m) focal plane that has excellent image quality and small geometric distortions over a wide wavelength range (3000-10,600 A) in the imaging mode, and good image quality combined with very small lateral and longitudinal color errors in the spectroscopic mode. The unusual requirement of very low distortion is set by the demands of time-delay-and-integrate (TDI) imaging. (2) Very high precision motion to support open-loop TDI observations. (3) A unique wind baffle/enclosure construction to maximize image quality and minimize construction costs. The telescope had first light in 1998 May and began regular survey operations in 2000.

https://iopscience.iop.org/article/10.1086/500975/pdf

The 2.5 m Telescope of the Sloan Digital Sky Survey

Catalytic protein subunits of telomerase from the ciliate Euplotes aediculatus and the yeast Saccharomyces cerevisiae contain reverse transcriptase motifs. Here the homologous genes from the fission yeast Schizosaccharomyces pombe and human are identified. Disruption of the S. pombe gene resulted in telomere shortening and senescence, and expression of mRNA from the human gene correlated with telomerase activity in cell lines. Sequence comparisons placed the telomerase proteins in the reverse transcriptase family but revealed hallmarks that distinguish them from retroviral and retrotransposon relatives. Thus, the proposed telomerase catalytic subunits are phylogenetically conserved and represent a deep branch in the evolution of reverse transcriptases.

https://science.sciencemag.org/content/sci/277/5328/955.full.pdf

Telomerase catalytic subunit homologs from fission yeast and human

Telomere Shortening and Tumor Formation by Mouse Cells Lacking Telomerase RNA

Dye-doped sol-gel materials for two-photon absorption induced fluorescence

We developed an accurate and fast three-dimensional computer model for simulating realistic solid-state laser systems. An iteration of the beam propagation calculation was developed to account for the counterpropagation of the laser beams in the saturated gain medium and eventually obtain the converged solution for the output beam. An analytic method was devised to account for the curved cavity mirror and the surface deformation of the gain medium induced by the temperature gradient due to pump absorption. The temperature gradient induced thermal lensing and stress birefringence is also properly included in the model calculation. This model has been validated and shown to be very accurate and efficient for modeling three-dimensional laser systems in a personal computer.

Three-dimensional computer model for simulating realistic solid-state lasers

Europium doped alkaline earth fluoride [Eu:AEF2 (AE = Ca, Sr, Ba)] nanoparticles were synthesized and systematically incorporated into the core of modified chemical vapor deposition (MCVD)-derived silica-based preforms by solution doping. The resulting preforms were examined to determine the impact of the nanoparticles chemistry on the spectroscopic behavior of the glass. The dominant existence of Eu3+ was demonstrated in all preforms, which is in contrast to conventional solution doped preforms employing dissolved europium salts where Eu2+ is primarily observed. Raman spectroscopy and fluorescence lifetime measurements indicated that the nanoparticles composition is effective in controlling, at a local chemical and structural level, the spectroscopic properties of active dopants in optical fiber glasses. Further, there is a systematic and marked increase in radiative lifetime, τ, of the Eu3+ emission that follows the cationic mass; τCa < τSr < τBa with the BaF2-derived sample yielding a 37% lengthening of the lifetime over the CaF2-derived one. Such nanoscale control of what otherwise is silica glass could be useful for realizing property-enhanced and tailored spectroscopic performance from otherwise “standard” materials, e.g., vapor-derived silica, in next generation optical fibers.

https://commons.erau.edu/cgi/viewcontent.cgi?article=1755&context=publication

Spectral engineering of optical fiber preforms through active nanoparticle doping

The fluorescence decay of the 4F3/2 state of the Nd3+ ions was studied in Nd3+, Er3+ and Nd3+, Ho3+ doped crystals of garnets and perovskites. Fast initial decays were observed in this system for the first time to our knowledge and are attributed to an energy transfer from the Nd3+ ion to the nearest codopant ions that can accept the energy. Mathematical models of the decay processes were tested, and agreement with the experimental data was obtained by including a short-range interaction responsible for the fast initial decay and a dipole–dipole interaction for the subsequent decay.

Nd 3+ to Er 3+ and Nd 3+ to Ho 3+ energy transfer in laser crystals

The fluorescence emission spectra of Cr:Nd:YAG crystal are measured and the effective stimulated emission cross-section of the crystal is obtained from −80 to +80 °C. A linear temperature dependence between −80 and +80 °C is reported for the 1.064-μm peak stimulated emission cross-section of Cr:Nd:YAG crystal.

Michael Bass

Papers

Dye-doped sol-gel materials for two-photon absorption induced fluorescence

Three-dimensional computer model for simulating realistic solid-state lasers

Spectral engineering of optical fiber preforms through active nanoparticle doping

Nd 3+ to Er 3+ and Nd 3+ to Ho 3+ energy transfer in laser crystals

Temperature dependence of the 1.064-μm stimulated emission cross-section of Cr:Nd:YAG crystal