Aqwest (United States)

Analysis of ancient desiccated feces - termed paleofeces or coprolites - can unlock insights into the lives of ancient people. We collected desiccated feces from caves in the Rio Zape Valley in Mexico (725-920 CE). First, we extracted DNA with methods previously optimized for paleofeces. Then, we applied highly sensitive modern molecular tools (i.e., PCR pre-amplification followed by multi-parallel qPCR) to assess the presence of 30 enteric pathogens. We detected ≥1 pathogen associated gene in each of the ten samples and a mean of 3.9 pathogens per sample. The targets detected included Blastocystis spp. (n=7), atypical enteropathogenic E. coli (n=7), Enterobius vermicularis (n=6), Entamoeba spp. (n=5), enterotoxigenic E. coli (n=5), Shigella spp./enteroinvasive E. coli (n=3), Giardia spp. (n=2), and E. coli O157:H7 (n=1). The protozoan pathogens we detected (i.e., Giardia spp. and Entamoeba spp.) have been previously detected in paleofeces via enzyme-linked immunoassay (ELISA), but have not via PCR. This work represents the first detection of Blastocystis spp. atypical enteropathogenic E. coli, enterotoxigenic E. coli, Shigella spp./enteroinvasive E. coli, and E. coli O157:H7 in paleofeces. These results suggest that sensitive modern molecular tools, such as PCR, can be used to evaluate ancient materials for genes of interest.

Tm:Lu2O3 has a multi–featured absorption spectrum in the usual pump band around 796 nm with peaks and valleys narrower than the bandwidth of conventional pump diodes in this range. As a result, accurate prediction of the spatial deposition of absorbed pump power is rather challenging. This is of particular importance for the edge-pumped disk laser where the spatial gain profile is adjusted by temperature tuning of the laser pump diodes to optimize performance for amplification of pulses with spatial top hat or with spatial Gaussian profiles. The frequently used lumped-line pump model was found inadequate for Tm:Lu2O3. This work reports on the development of a spectral absorption model for a more accurate prediction of pump power deposition and its correlation with the gain uniformity and amplifier output pulse energy.

We report on a Yb:YAG laser amplifier for ultrashort pulse applications at kW-class average power. The laser uses two large-aperture, disk-type gain elements fabricated from composite ceramic YAG material, and a multi-pass extraction architecture to obtain high gain in a chirped-pulse amplification system. The disks are edge-pumped, thus allowing for reduced doping of host material with laser ions, which translates to lower lasing threshold and lower heat dissipation in the Yb:YAG material. The latter makes it possible to amplify a near diffraction-limited seed without significant thermo-optical distortions. This work presents results of testing the laser amplifier with relay optics configured for energy extraction with up to 40 passes through the disks. Applications for the ultrashort pulse laser amplifier include producing laser-induced plasma channel, laser material ablation, and laser acceleration of atomic particles.

We report on a new class of laser amplifiers for inertial confinement fusion (ICF) drivers based on a Yb:YAG ceramic disk in an edge-pumped configuration and cooled by a high-velocity gas flow. The Yb lasant offers very high efficiency and low waste heat. The ceramic host material has a thermal conductivity nearly 15-times higher than the traditionally used glass and it is producible in sizes suitable for a typical 10- to 20-kJ driver beam line. The combination of high lasant efficiency, low waste heat, edge-pumping, and excellent thermal conductivity of the host, enable operation at 10 to 20 Hz at over 20% wall plug efficiency while being comparably smaller and less costly than recently considered face-pumped alternative drivers using Nd:glass, Yb:S-FAP, and cryogenic Yb:YAG. Scalability of the laser driver over a broad range of sizes is presented.

We report on a novel heat sink for high-power laser diodes offering unparalleled capacity in high-heat flux handling and temperature control. The heat sink uses a liquid coolant flowing at high speed in a miniature closed and sealed loop. Diode waste heat is received at high flux and transferred to environment, coolant fluid, heat pipe, or structure at a reduced flux. When pumping solid-state or alkali vapor lasers, diode wavelength can be electronically tuned to the absorption features of the laser gain medium. This paper presents the heat sink physics, engineering design, performance modeling, and configurations.