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

Laser action in Cr4+ doped yttrium‐orthosilicate Cr4+:Y2SiO5 cooled to 77 K was demonstrated for the first time with 1064 and 532 nm pumping from a pulsed Nd:YAG laser and broad band (@ 840 nm) pumping from a Q‐switched Cr:LiSAF laser.

/pdf/laser-performance-of-cr4-y2sio5-1n5hhefcxo.pdf

Laser performance of Cr4+:Y2SiO5

Geometrical and physical optics, polarized light, components and instruments

Spectroscopic properties of neodymium-doped yttrium orthovanadate crystals were measured in the temperature range between 5 and 350 K. Crystals fabricated by different suppliers, with 0.3 and 1 at% Nd3+, were compared. For each temperature, the stimulated emission cross sections of the Nd3+ 4F3/2 decay to the 4I9/2, 4I11/2, and 4I13/2 states were obtained using the Fuchtbauer-Ladenburg and the reciprocity techniques. Nd:YVO4 shows higher absorption at room temperature and higher stimulated emission cross section with similar variation with temperature when compared with Nd:YAG. The anomalous dependence on temperature of the Nd3+ 4F3/2 excited-state lifetime is discussed and an explanation is suggested.

Michael Bass

Papers

Laser performance of Cr4+:Y2SiO5

Geometrical and physical optics, polarized light, components and instruments

Temperature-dependent stimulated emission cross section in Nd 3+ :YVO 4 crystals

Design, fabrication, and testing; sources and detectors; radiometry and photometry

Up conversion luminescence of Yb3+-Er3+ codoped CeO2 nanocrystals with imaging applications