Review of river fisheries valuation in Central and South America

Unlike Africa and Asia, where a large part of the population are heavily dependent upon fishing for their livelihoods, fishing for a living in the interior of Central and South America (CSA) remains a marginal occupation for all but the most isolated of families. As such, the economics and management of fisheries on the continent have received little attention from within the continent and the rest of the world. This study shows that while a number of studies have been carried out on fishing in the region, they tend to be limited in their geographical focus and time scale. Although fishing of freshwater species may appear to be comparatively insignificant in the region, the rivers of CSA are very important. This report attempts to analyze the literature available on CSA river fisheries and attempts to draw out an economic value of these fisheries. It is divided into a number of sections. First, the authors describe the major river basins on the continent, characterize their fisheries, and place freshwater fisheries in CSA into a global context. Second, the authors provide a review of valuation techniques for fisheries and use this analytical framework to review the principal literature on freshwater fisheries in the region. Then they turn their attention to the economic impact of dams and water abstraction schemes, reviewing the available literature to ascertain how/if economic values are computed for the impact on fisheries. Finally, they offer some conclusions and recommendations on the direction for future studies of freshwater fisheries in CSA

Phase-stabilized, 1.5-W frequency comb at 2.8 to 4.8 micron

We present a high-power optical parametric oscillator-based frequency comb in the mid-infrared wavelength region using periodically poled lithium niobate. The system is synchronously pumped by a 10-W femtosecond Yb:fiber laser centered at 1.07 um and is singly resonant for the signal. The idler (signal) wavelength can be continuously tuned from 2.8 to 4.8 um (1.76 to 1.37 um) with a simultaneous bandwidth as high as 0.3 um and a maximum average idler output power of 1.50 W. We also demonstrate the performance of the stabilized comb by recording the heterodyne beat with a narrow-linewidth diode laser. This OPO is an ideal source for frequency comb spectroscopy in the mid-IR.Comment: 4 figure

Magnetic properties of microtektites Semiannual status report, 1 Jan. - 31 Jun. 1969

Magnetic susceptibility, magnetization, and Curie constants for normal and bottle-green microtektites found in deep-sea sediment core

Extremely Anisotropic Scintillations

A small number of quasars exhibit interstellar scintillation on time-scales less than an hour; their scintillation patterns are all known to be anisotropic. Here we consider a totally anisotropic model in which the scintillation pattern is effectively one-dimensional. For the persistent rapid scintillators J1819+3845 and PKS1257-326 we show that this model offers a good description of the two-station time-delay measurements and the annual cycle in the scintillation time-scale. Generalising the model to finite anisotropy yields a better match to the data but the improvement is not significant and the two additional parameters which are required to describe this model are not justified by the existing data. The extreme anisotropy we infer for the scintillation patterns must be attributed to the scattering medium rather than a highly elongated source. For J1819+3845 the totally anisotropic model predicts that the particular radio flux variations seen between mid July and late August should repeat between late August and mid November, and then again between mid November and late December as the Earth twice changes its direction of motion across the scintillation pattern. If this effect can be observed then the minor-axis velocity component of the screen and the orientation of that axis can both be precisely determined. In reality the axis ratio is finite, albeit large, and spatial decorrelation of the flux pattern along the major axis may be observable via differences in the pairwise fluxes within this overlap region; in this case we can also constrain both the major-axis velocity component of the screen and the magnitude of the anisotropy.Comment: 5 pages, 4 figures, MNRAS submitte

Preliminary ultraviolet reflectance of some rocks and minerals from 2000 angstrom to 3000 angstrom

Ultraviolet reflectance measurements of rocks and minerals from 2000 A to 3000

Variability of the southern Antarctic Circumpolar Current front north of South Georgia

South Georgia (54°S, 37°W) is an island in the eastern Scotia Sea, South Atlantic that lies in the path of the Antarctic Circumpolar Current (ACC). The southern ACC front (SACCF), one of three major fronts associated with the ACC, wraps anticyclonically around South Georgia and then retroflects north of the island. This paper investigates temporal variability in the position of the SACCF north of South Georgia that is likely to have an effect on the South Georgia ecosystem by contributing to the variability in local krill abundance. A meridional hydrographic section that crossed the SACCF three times demonstrates that the SACCF is associated with a geopotential anomaly of 4.5 J kg-1 in the eastern Scotia Sea. A high resolution (1/4°×1/4°) map of historical geopotential anomaly shows the mean position of the SACCF retroflection north of South Georgia to be at 36°W, 400 km further east than in previous work. It also reveals temporal variability associated with the SACCF in the South Georgia region. A near-surface drifter provides evidence for variability in the western extent of the SACCF north of South Georgia and for the presence of eddies in the region. Output from a 3-year (1993–1995) high frequency wind forced run of the eddy-permitting Ocean Circulation and Climate Advanced Modelling project (OCCAM) model, used to investigate the frontal variability, shows two periods of anomalous westward extent of the SACCF north of South Georgia and associated eddy-shedding. The SACCF variability affects the near-surface transport of passive drifters into the region with implications for the South Georgia ecosystem

Carbon-ammonia pairs for adsorption refrigeration applications : ice making, air conditioning and heat pumping

A thermodynamic cycle model is used to select an optimum adsorbent-refrigerant pair in respect of a chosen figure of merit that could be the cooling production (MJ m(-3)), the heating production (MJ m(-3)) or the coefficient of performance (COP). This model is based mainly on the adsorption equilibrium equations of the adsorbent-refrigerant pair and heat flows. The simulation results of 26 various activated carbon-ammonia pairs for three cycles (single bed, two-bed and infinite number of beds) are presented at typical conditions for ice making, air conditioning and heat pumping applications. The driving temperature varies from 80 degrees C to 200 degrees C. The carbon absorbents investigated are mainly coconut shell and coal based types in multiple forms: monolithic, granular, compacted granular, fibre, compacted fibre, cloth, compacted cloth and powder. Considering a two-bed cycle, the best thermal performances based on power density are obtained with the monolithic carbon KOH-AC, with a driving temperature of 100 degrees C; the cooling production is about 66 MJ m(-3) (COP = 0.45) and 151 MJ m(-3) (COP = 0.61) for ice making and air conditioning respectively; the heating production is about 236 MJ m(-3) (COP = 1.50)

The analysis of samples of milk referred to the Government Laboratory in connection with the Sale of Food and Drugs Act

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New rapid-curing, stable polyimide polymers with high-temperature strength and thermal stability

Additive-type polymerization reaction forms thermally stable polyimide polymers, thereby eliminating the volatile matter attendant with the condensation reaction. It is based on the utilization of reactive alicyclic rings positioned on the ends of polyimide prepolymers having relatively low molecular weights