Southern California partyboat sampling study Quarterly Report no. 1

Estimates of the total yearly catch from the partyboat fishery have been collected and published on a routine basis since 1935. Important data relating to the size and age composition of this segment of the marine sportfishery have been lacking. As a consequence, a southern California partyboat sampling study was initiated on April 1, 1975. The main objective of this sampling is to identify and measure all fishes taken by sportsmen on partyboats with primary emphasis given to California barracuda, Sphyraena argentea; yellowtail, Seriola dorsalis; white seabass, Cynoscion nobilis; and rockfishes, Sebastes spp. (22pp.

Southern California partyboat sampling study Quarterly Report No. 4

From 1 April through 30 June, 1976, Department personnel made 146 trips aboard southern California partyboats. A total of 18,218 fishes from 76 species was identified and measured. Otoliths were removed from 674 rockfish carcasses for use in age determination studies. The 10 most common species sampled during this quarter represented 85.2% of the total number of fishes measured. These were, in order of importance: bocaccio, Sebastes paucispinis; kelp bass, Paralabrax clathratus; Pacific bonito, Sarda chiliensis; barred sand bass, Paralabrax nebulifer; chilipepper, Sebastes goodei; California barracuda, Sphyraena argentea; olive rockfish; Sebastes serranoides; white croaker, Genyonemus lineatus; ocean whitefish, Caulolatilus princeps; and vermilion rockfish, Sebastes miniatus. Pacific bonito and California barracuda partyboat landings exceeded those of the entire 1975 season, and sampling data indicate the average length of barracuda caught from partyboats was significantly larger than that of the previous season. (15pp.

Southern California partyboat sampling study Quarterly Report no. 3

During the period January 1 to March 31, 1976, Department personnel made 139 sampling trips aboard southern California partyboats. A total of 22,122 fishes from 73 species was identified and measured. Otoliths were removed from 1,536 rockfish carcasses representing 31 species for use in age determination. Sampling personnel tagged and released 68 California barracuda, Sphyraena argentea, and 18 sablefish, Anoplopoma fimbria. The five most common species sampled during this period represented approximately 79% of the total number of fishes measured. These were, in order of importance; bocaccio, Sebastes paucispinis; chilipepper, Sebastes goodei; olive rockfish, Sebastes serranoides; greenspotted rockfish, Sebastes chlorostictus; and vermilion rockfish, Sebastes miniatus. Bocaccio alone accounted for 52% of the sampled catch. (15pp.

Dichroic atomic vapor laser lock with multi-gigahertz stabilization range

A dichroic atomic vapor laser lock (DAVLL) system exploiting buffer-gas-filled millimeter-scale vapor cells is presented. This system offers similar stability as achievable with conventional DAVLL system using bulk vapor cells, but has several important advantages. In addition to its compactness, it may provide continuous stabilization in a multi-gigahertz range around the optical transition. This range may be controlled either by changing the temperature of the vapor or by application of a buffer gas under an appropriate pressure. In particular, we experimentally demonstrate the ability of the system to lock the laser frequency between two hyperfine components of the $^{85}$Rb ground state or as far as 16 GHz away from the closest optical transition.Comment: 11 pages, 7 figures. Published in Review of Scientific Instruments 201

Stochastic Algorithms for Large-Scale Composite Optimization: the Case of Single-Shot X-FEL Imaging

We apply a recently developed framework for analyzing the convergence of stochastic algorithms to the general problem of large-scale nonconvex composite optimization more generally, and nonconvex likelihood maximization in particular. Our theory is demonstrated on a stochastic gradient descent algorithm for determining the electron density of a molecule from random samples of its scattering amplitude. Numerical results on an idealized synthetic example provide a proof of concept. This opens the door to a broad range of algorithmic possibilities and provides a basis for evaluating and comparing different strategies. While this case study is very specific, it shares a structure that transfers easily to many problems of current interest, particularly in machine learning.Comment: 20 pages, 10 figure

Utilized Metabolizable Energy and its Impacts on the Management of Grass Pastures in the Central Chaco of Paraguay

Animal production from sown pastures of Gatton Panic (Panicum maximum Jacq.) and Estrella (Cynodon nlemfuënsis Vand.) on a luvic Kastanozem in the Central Chaco of Paraguay (mean annual rainfall 850 mm) was measured over two years (Sep. 1992 to Nov. 1994). The pastures were grazed continuously by Brahman X Hereford steers at six stocking densities, ranging from 0.5 to 2.0 American Animal Units (1 AU = 454 kg) per hectare. Herbage availability, chemical composition (ME, XP, fibre) and cattle liveweight gains were measured at four weekly intervals. Building regression models for Utilized metabolizable energy (UME in GJ/ha) and ME requirements for maintenance (RM in GJ/ha) over stocking densities, the maximum energy conversion was obtained with 1.8 AU/ha. At this stocking density, 29 % of UME was transformed into liveweight gain. The calculated intersect of the UME and RM functions occured at a stocking density of 3.4 AU/ha when, theoretically, animals only maintain their body weight

Measuring rhizosphere hydraulic properties: impact of root mucilage on soil hydraulic conductivity and water retention curve

Roots are hypothesized to alter rhizosphere hydraulic properties by release of mucilage. This mechanism is expected to have strong implications for root water uptake under drought conditions. Direct measurement of rhizosphere hydraulic properties is hindered by the dynamic nature of the components involved; root hydraulics change with ontology; mucilage production, composition and diffusion are not constant; soil water content changes. An experimental approach was developed which enables to simultaneously measure hydraulic conductivity and apparent water retention curve in a radial flow setup, mimicking the flow geometry around roots. The method consists of extracting water at constant suction via a suction cup, which is centrally placed in a soil filled cylinder and recording water outflow and soil matric potential. In the past, the setup was tested for homogeneous distribution of a model substance (calcium-polygalacturonic acid) frequently used to mimic the properties of root mucilage. Now the system has been applied to investigate the impact of plant root mucilage collected from white lupine. As the system allows a local placement of mucilage treated soil around the suction cup to simulate a ‘rhizosphere’ between bulk soil and suction cup, it can be set up with the limited quantity of natural plant root mucilage available from direct collection. Quartz sand has been treated with lupine root mucilage by mixing liquid mucilage with dry sand at a concentration of 2 mg mucilage per gram soil. Treated sand has been placed as a circular layer with 3.75 mm thickness around the suction cup, which has a radius of 1.25 mm. All around this layer, the device has been filled up with untreated sand. The radius of the whole device was 25 mm. To determine soil hydraulic conductivity we inversely fitted the outflow curves and soil matric potential by solving the Richards’ equation in radial coordinates. Water outflow curves show a significant impact of lupine mucilage on water flow rate – it slows water flow from bulk soil to suction cup. Currently modelling is in process to determine soil hydraulic conductivity and water retention curves. Decreasing hydraulic conductivities and increasing water retention due to lupine mucilage treatment are expected