Effects on Brood Development in the Carpenter Ant Mayr after Exposure to the Yeast Associate Kloecker.

The yeast is associated with the infrabuccal pocket in the carpenter ant (Hymenoptera: Formicidae), but its role in ant development is poorly defined. The potential effects of this yeast on brood development were examined on sets of larval groups and workers over a 12 week period. Worker-larval sets were fed variations of a completely artificial, holidic diet and exposed or not exposed to live Worker-larval sets in half of the experiment were defaunated using a two-step heat and chemical process.

Singular value decomposition approach to coherent averaging in digital holography.

We present a new approach to coherent averaging in digital holography using singular value decomposition (SVD). Digital holography enables the extraction of phase information from intensity measurements. For this reason, SVD can be used to statistically determine the orthogonal vectors that align the complex-valued measurements from multiple frames and group common modes accounting for constant phase shift terms.

Role of Leaf Litter in Above-Ground Wood Decay.

The effects of leaf litter on moisture content and fungal decay development in above-ground wood specimens were assessed. Untreated southern pine specimens were exposed with or without leaf litter contact. Two types of leaf litter were evaluated; aged (decomposed) and young (early stages of decomposition).

Imaging through extreme scattering in extended dynamic media.

Critical to navigation, situational awareness, and object identification is the ability to image through turbid water and fog. To date, the longest imaging ranges in such environments rely on active illumination and selection of ballistic photons by means of time gating. Here we show that the imaging range can be extended by using time-gated holography in combination with multi-frame processing.

Gated holographic imaging for structured illumination through obscurations.

We describe a pulsed phase conjugator system that projects a laser beam possessing a scene-dependent energy distribution. We expand upon the inherent properties of optical phase conjugation (OPC) to include not only corrections for phase aberrations but to provide targeted laser beam illumination of partially obscured objects. For instance, if incorporated into a foliage-penetrating lidar system, OPC could significantly enhance performance.

Laboratory Evaluations of Durability of Southern Pine Pressure Treated With Extractives From Durable Wood Species.

Extracts from sawdust of four naturally durable wood species [Alaskan yellow cedar, AYC, Cupressus nootkanansis D. Don 1824; eastern red cedar, ERC, Juniperus virginiana L.; honey mesquite, HM, Prosopis glandulosa Torr.

Weak-signal iterative holography.

An iterative holographic table-top experiment is presented, where a recorded hologram is used to re-illuminate the initial target. With this beam shaping setup, more light is directed to the target for each iteration until a convergence limit is met. We experimentally examine convergence properties of this iterative hologram reconstruction approach for weak object signals and compare with theory.

Limits of bootstrapping in a weak-signal holographic conjugator.

We explore the effect of noise on the energy convergence for extremely weak signals in the object field of a holographic experiment. The impact of noise for the energy-on-target in the iterative, bootstrapping process of a holographic phase conjugator system is theoretically derived to obtain a recursive analytical solution. Theoretical results are compared with numerical simulations for a weak-signal holographic conjugator.

Effect of simulated rainfall and weathering on release of preservative elements from CCA treated wood.

The release of arsenic from wood pressure-treated with chromated copper arsenate (CCA) can be decreased by application of wood finishes, but little is known about the types of finishes that are best suited for this purpose. This study evaluated the effects of finish water repellent content and ultraviolet (UV) radiation on the release of arsenic, copper, and chromium from CCA-treated wood exposed to simulated rainfall. Deck boards treated with CCA were either left unfinished or dipped in a finish prepared with 1%, 3%, or 5% water repellent.

Optimization of the field of view of a Brillouin-enhanced four-wave-mixing phase conjugator.

A Brillouin-enhanced four-wave mixing phase conjugator featuring a field of view that varies by approximately an order of magnitude, i.e., from 2 to 20 mrad, is described.

Phase conjugation through Brillouin-enhanced four-wave mixing over an extended atmospheric path.

We report what is to our knowledge the first demonstration of Brillouin-enhanced four-wave mixing over a long atmospheric path. Weak laser light reflected from a remote retroreflector was input to a high-gain conjugate mirror. The resulting amplified output returns to the retroreflector owing to its phase-conjugate nature.

Improvements to a home-built nitrogen laser.

Several major design improvements to a previously described nitrogen laser are presented. The active region has a larger cross section but shorter length resulting in an output beam of better optical quality and a laser channel which is cheaper and easier to build. The gas flow is transverse to the channel, and the pressure is more uniform.

Improvements to a home-built nitrogen laser.

Several major design improvements to a previously described nitrogen laser are presented. The active region has a larger cross section but shorter length resulting in an output beam of better optical quality and a laser channel which is cheaper and easier to build. The gas flow is transverse to the channel, and the pressure is more uniform.