Investigation into the factors associated with poor water quality in intensively cultured prawn ponds

Water quality problems are reported to be the factor limiting prawn production in the local prawn farm. This investigation was carried out to monitor water quality and its relationship to physical, chemical and biological conditions in the ponds in order to establish what factors should be monitored in order to predict problems. Pond collapse was found to be associated with high concentrations of ammonium, high pH and blue-green algae dominated phytoplankton populations. There was no easy means of predicting the imminent collapse of ponds as the phenomenon was never associated with the extreme of any of the conditions monitored. Rather it seemed to be related to the stability of the pond's algal population, which was largely unaccounted for. Recommendations toward improving water quality are proposed.

A preliminary assessment of water quality in fish cages on Lake Kariba, Zimbabwe

The water quality in fish cages on Lake Kariba was studied. The Kruskal-Wallis test was used to determine whether the water quality parameters differed significantly among the cage-types (cage-type effect). Secchi disc readings ranged from 2 to 4 metres, while temperature ranged from 23 degree C to 29.5 degree C. The observed conductivity was between 98.7 mu S/cm and 102.3 mu S/cm. The pH was between 6.31 and 7.82. Concentrations of dissolved oxygen varied from 1.55 to 6.47 mg/l, while dissolved oxygen saturation ranged from 22.3% to 83.1%. Within the same month, temperature did not differ significantly among cages. Conductivity, pH, dissolved oxygen concentration and dissolved oxygen saturation differed significantly among the 3 cage-types. Temperature and pH levels in the cages were close to the optimum levels for the culture of cichlids. Sub-optimal levels of dissolved oxygen occurred occasionally in the octagonal cages.

A New Method for Feedback on the Quality of Chest Compressions during Cardiopulmonary Resuscitation

Quality of cardiopulmonary resuscitation (CPR) improves through the use of CPR feedback devices. Most feedback devices integrate the acceleration twice to estimate compression depth. However, they use additional sensors or processing techniques to compensate for large displacement drifts caused by integration. This study introduces an accelerometer-based method that avoids integration by using spectral techniques on short duration acceleration intervals. We used a manikin placed on a hard surface, a sternal triaxial accelerometer, and a photoelectric distance sensor (gold standard). Twenty volunteers provided 60 s of continuous compressions to test various rates (80-140 min(-1)), depths (3-5 cm), and accelerometer misalignment conditions. A total of 320 records with 35312 compressions were analysed. The global root-mean-square errors in rate and depth were below 1.5 min(-1) and 2 mm for analysis intervals between 2 and 5 s. For 3 s analysis intervals the 95% levels of agreement between the method and the gold standard were within -1.64-1.67 min(-1) and -1.69-1.72 mm, respectively. Accurate feedback on chest compression rate and depth is feasible applying spectral techniques to the acceleration. The method avoids additional techniques to compensate for the integration displacement drift, improving accuracy, and simplifying current accelerometer-based devices.

Feedback systems for the quality of chest compressions during cardiopulmonary resuscitation

167 p.

Cuando el miedo invade la ficción. Análisis de Perdidos (Lost) y de otros quality dramas de la era Post 11S.

521 p.

Assessment of habitat quality for juvenile California halibut (Paralichthys californicus) in a seasonally arid estuary

We evaluated habitat quality for juvenile California halibut (Paralichthys californicus) in a Pacific Coast estuary lacking in strong salinity gradients by examining density, recent otolith growth rates, and gut fullness levels of wild-caught and caged juveniles for one year. Juveniles <200 mm standard length were caught consistently in the inner, central, and outer sections of the estuary. The density of juveniles was two times higher in the inner estuary during most of the year, consistent with active habitat selection by part of the population. A generalized linear model indicated temperature, sampling time, and the interaction between salinity and temperature were significantly related to density. However, the model explained only 21% of the variance. Gut fullness levels of wild-caught juveniles were highest during the summer, but recent otolith growth rates were not related to temperature. The proportion of individuals feeding successfully indicated that seasonal differences in food availability are more important than spatial variation in prey abundance in driving feeding success. Feeding success of caged fishes was limited, precluding the use of growth rates as indicators of local habitat quality. However, marginal increment widths were reliable indicators of somatic growth at low growth rates over two-week periods. The relatively high growth rates and abundance of small wild-caught juveniles found throughout the estuary indicates that the entire estuary system has the potential for serving as nursery habitat.

Aspects of quality control of wind profiler measurements in complex topography

It is well known in the scientific community that some remote sensing instruments assume that sample volumes present homogeneous conditions within a defined meteorological profile. At complex topographic sites and under extreme meteorological conditions, this assumption may be fallible depending on the site, and it is more likely to fail in the lower layers of the atmosphere. This piece of work tests the homogeneity of the wind field over a boundary layer wind profiler radar located in complex terrain on the coast under different meteorological conditions. The results reveal the qualitative importance of being aware of deviations in this homogeneity assumption and evaluate its effect on the final product. Patterns of behavior in data have been identified in order to simplify the analysis of the complex signal registered. The quality information obtained from the homogeneity study under different meteorological conditions provides useful indicators for the best alternatives the system can offer to build wind profiles. Finally, the results are also to be considered in order to integrate them in a quality algorithm implemented at the product level.