Foraging Behavior of Nerodia clarkii compressicauda, with Special Reference to Lingual Luring

Predators use a variety of tactics with which to obtain prey. Here, I describe lingual luring by the mangrove saltmarsh snake (Nerodia clarkii compressicauda), a somewhat unique behavior that involves the use of the tongue to attract fish prey close enough to permit their capture. The lure is characterized by considerable upward curling of the distal portion of the tongue as it protrudes from the mouth. In addition, luring tongue flicks are significantly greater in duration than chemosensory tongue flicks. Both visual and chemical cues are sufficient to stimulate lingual luring, the latter more so than the former. However, both types of cues together have a strong synergistic effect on elicitation of the behavior. Luring behavior presents primarily a visual stimulus, as its frequency was reduced in the dark. Although prey density had no effect on the exhibition of luring by these snakes, prey density did have an effect on their activity level and their choice of foraging sites. N. c. compressicauda was a fairly active forager under the conditions tested in these studies, but its use of a largely sit-and-wait tactic such as predatory luring indicates that this species uses more of a mixed foraging strategy. The foraging behavior of the snakes differed at different levels of habitat structural density, created by using simulated prop roots in a laboratory arena. When no prop-root structure was present, the snakes rarely ventured into open water. However, they spent significantly more time in the water if prop roots were present. Such habitat structure may serve as protection from larger predators that may be impeded by it

Synchronous photoinjection using a frequency-doubled gain-switched fiber-coupled seed laser and ErYb-doped fiber amplifier

Light at 1560 nm from a gain-switched fiber-coupled diode laser and ErYb-doped fiber amplifier was frequency doubled to obtain over 2 Waverage power at 780 nm with ~40 ps pulses and pulse repetition rate of 499 MHz. This light was used to drive the 100 kV DC high voltage GaAs photoemission gun at the Continuous Electron Beam Accelerator Facility at Jefferson Laboratory to produce a high average current beam (100 μA) of highly spin-polarized electrons ( \u3e 80%). This new drive-laser system represents a significant advance over laser systems used previously, providing significantly higher power and enhanced reliability

Synchronous photoinjection using a frequency-doubled gain-switched fiber-coupled seed laser and ErYb-doped fiber amplifier

Light at 1560 nm from a gain-switched fiber-coupled diode laser and ErYb-doped fiber amplifier was frequency doubled to obtain over 2 Waverage power at 780 nm with ~40 ps pulses and pulse repetition rate of 499 MHz. This light was used to drive the 100 kV DC high voltage GaAs photoemission gun at the Continuous Electron Beam Accelerator Facility at Jefferson Laboratory to produce a high average current beam (100 μA) of highly spin-polarized electrons ( \u3e 80%). This new drive-laser system represents a significant advance over laser systems used previously, providing significantly higher power and enhanced reliability

Fast Robust Shortest Path Computations

We develop a fast method to compute an optimal robust shortest path in large networks like road networks, a fundamental problem in traffic and logistics under uncertainty. In the robust shortest path problem we are given an s-t-graph D(V,A) and for each arc a nominal length c(a) and a maximal increase d(a) of its length. We consider all scenarios in which for the increased lengths c(a) + bar{d}(a) we have bar{d}(a) <= d(a) and sum_{a in A} (bar{d}(a)/d(a)) <= Gamma. Each path is measured by the length in its worst-case scenario. A classic result [Bertsimas and Sim, 2003] minimizes this path length by solving (|A| + 1)-many shortest path problems. Easily, (|A| + 1) can be replaced by |Theta|, where Theta is the set of all different values d(a) and 0. Still, the approach remains impractical for large graphs. Using the monotonicity of a part of the objective we devise a Divide and Conquer method to evaluate significantly fewer values of Theta. This methods generalizes to binary linear robust problems. Specifically for shortest paths we derive a lower bound to speed-up the Divide and Conquer of Theta. The bound is based on carefully using previous shortest path computations. We combine the approach with non-preprocessing based acceleration techniques for Dijkstra adapted to the robust case. In a computational study we document the value of different accelerations tried in the algorithm engineering process. We also give an approximation scheme for the robust shortest path problem which computes a (1 + epsilon)-approximate solution requiring O(log(d^ / (1 + epsilon))) computations of the nominal problem where d^ := max d(A) / min (d(A){0})

Tanapseudes gutui, a New Species of Apseudomorphan Tanaidacea (Crustacea: Peracarida) from the Caribbean Sea and the Taxonomic Status of the Family Tanapseudidae Băcescu

Tanapseudes gutui, n. sp., is described from depths of 3–34 m off San Juan, Puerto Rico, and 4– 5 m off Goat Island, Tobago. Tanapseudes sinensis Bamber from Hong Kong waters is re-examined and determined to represent a junior synonym of the type species T. ormuzana Băcescu which was originally collected in the Straights of Hormuz off Iran. Tanapseudes gutui can be distinguished from T. ormuzana by several characters including details of the mouth parts, the presence of a reduced spiniform seta on the distotergal margin of the propodus of pereopod 1, pereonites 3–6 with rounded anterior margins, and a pleotelson lacking a mid-lateral lobe. A neotype is established for T. ormuzana based on a specimen collected from near the original type locality, and its mouth parts and pereopod 1 are illustrated. Largely based on the absence of a palp on the maxillule and the presence of a bifurcate seta on the dactyl of pereopod 1, the family Tanapseudidae Băcescu is now considered a subfamily within the family Kalliapseudidae Lang sensu Gutu. The genus Paradoxapseudes Gutu, formerly within the family Tanapseudidae sensu Gutu, is tentatively transferred to the family Apseudidae Leach

Carpoapseudes heardi N. Sp. (Tanaidacea: Apseudomorpha) from Caribbean Waters Near Tobago

Carpoapseudes heardi n. sp. is described from samples collected from depths of 421 and 537 m off Tobago and is the first Caribbean record for the genus. The new species bears a resemblance to Carpoapseudes serratospinosus Lang, 1968 and other related species in the shortened dactylus unguis combination of pereopod 1, but has parallel eyespines like Carpoapseudes bacescui Guţu, 1975 and Carpoapseudes simplicirostris (Norman and Stebbing, 1886). Other diagnostic characters include pereopods 2 and 3 with basal spurs, labrum with paired lobes, labial palp with two terminal setae, maxillipedal bases with outer crenulations, and pleopods with 1-articled rami. It was found to lack an epistomal spine and has an unusual form of the third pereopod short propodal spine

Convergence of Successive Linear Programming Algorithms for Noisy Functions

Gradient-based methods have been highly successful for solving a variety of both unconstrained and constrained nonlinear optimization problems. In real-world applications, such as optimal control or machine learning, the necessary function and derivative information may be corrupted by noise, however. Sun and Nocedal have recently proposed a remedy for smooth unconstrained problems by means of a stabilization of the acceptance criterion for computed iterates, which leads to convergence of the iterates of a trust-region method to a region of criticality, Sun and Nocedal (2022). We extend their analysis to the successive linear programming algorithm, Byrd et al. (2023a,2023b), for unconstrained optimization problems with objectives that can be characterized as the composition of a polyhedral function with a smooth function, where the latter and its gradient may be corrupted by noise. This gives the flexibility to cover, for example, (sub)problems arising image reconstruction or constrained optimization algorithms. We provide computational examples that illustrate the findings and point to possible strategies for practical determination of the stabilization parameter that balances the size of the critical region with a relaxation of the acceptance criterion (or descent property) of the algorithm

Tanaidacea (Crustacea: Peracardia) of the Gulf of Mexico. IX. Geographical Occurrence of Apseudes olimpiae Gutu, 1986 with a Review of Previous Records for the Genus Apseudes in the Gulf

Examination of tanaidacean specimens collected from shelf waters of the eastern Gulf of Mexico (Gulf) revealed the presence of the apseudomorph Apseudes olimpiaeGutu, 1986, whose type locality was unknown, but suspected to be Bermuda. It is now determined that the type material actually came from the northeastern Gulf. Although the specific station locality information for the type material has been lost; records indicate that specimens from the Gulf were sent to Romania for study by M. Băcescu and apparently became mixed with material from Bermuda. Based on additional material from the present study, new locality records are established for A. olimpiae in shelf waters (19–47 m) off the coasts of Alabama and northwestern Florida. The original illustrations of Gutu (1986) are reproduced to facilitate the identification of A. olimpiae and a map of its known distribution is provided. A brief review of previous records for the genus Apseudes Leach, 1814 indicates that A. olimpiae is currently the only described species of the genus sensu stricto known with certainty from Gulf waters. The taxonomic status for Gulf specimens of another species in the A. intermedius-bermudeus complex and the “Apseudes sp. A” of Flint and Holland (1980) remain unresolved