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471.
472.
Effects of mechanical aeration on evaporation rate and water temperature in aquaculture ponds
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Water temperature and water loss by evaporation were monitored in control ponds and in ponds with different rates of aeration (9.2, 18.4, 27.6 and 36.9 kW/ha). The mean decrease in water temperature at 70‐cm depth was greater than that at the surface in aerated ponds than in control ponds. The greater the aeration rate, the cooler was water, both at the surface and at 70 cm. Evaporation rates were found to increase with greater aeration rate. Water loss increased by 32%–92% over 24‐hr periods in ponds with one to four 0.37‐kW Air‐O‐Lator aerators, respectively. The nutrient‐enriched control pond was more turbid, had cooler surface and deep water temperature, and had greater evaporation loss than the control pond without nutrient addition and less turbid water. But, aeration did not increase turbidity. Aeration can increase water loss from ponds and result in lower water temperature. Although aeration should not be used excessively in order to conserve water and reduce production cost, it is essential for many types of feed‐based aquaculture. 相似文献
473.
Busetto ML Moretti VM Moreno-Rojas JM Caprino F Giani I Malandra R Bellagamba F Guillou C 《Journal of agricultural and food chemistry》2008,56(8):2742-2750
Fatty acid composition and stable isotope ratios of carbon (delta(13)C) and nitrogen (delta(15)N) were determined in muscle tissue of turbot (Psetta maxima). The multivariate analysis of the data was performed to evaluate their utility in discriminating wild and farmed fish. Wild (n=30) and farmed (n=30) turbot of different geographical origins (Denmark, The Netherlands, and Spain) were sampled from March 2006 to February 2007. The application of linear discriminant analysis (LDA) and soft independent modeling of class analogy (SIMCA) to analytical data demonstrated the combination of fatty acids and isotopic measurements to be a promising method to discriminate between wild and farmed fish and between wild fish of different geographical origin. In particular, IRMS (Isotope Ratio Mass Spectrometry) alone did not permit us to separate completely farmed from wild samples, resulting in some overlaps between Danish wild and Spanish farmed turbot. On the other hand, fatty acids alone differentiated between farmed and wild samples by 18:2n-6 but were not able to distinguish between the two groups of wild turbot. When applying LDA isotope ratios, 18:2n-6, 18:3n-3, and 20:4n-6 fatty acids were decisive to distinguish farmed from wild turbot of different geographical origin, while delta(15)N, 18:2n-6, and 20:1n-11 were chosen to classify wild samples from different fishing zones. In both cases, 18:2n-6 and delta(15)N were determinant for classification purposes. We would like to emphasize that IRMS produces rapid results and could be the most promising technique to distinguish wild fish of different origin. Similarly, fatty acid composition could be used to easily distinguish farmed from wild samples. 相似文献
474.
François Rineau Jean-Paul Maurice Claude Nys Hubert Voiry Jean Garbaye 《Annals of Forest Science》2010,67(1):110-110
475.
Andrew K Claude Dean H Riedesel Elizabeth A Riedesel 《Veterinary anaesthesia and analgesia》2010,37(2):97-105
Objective To compare the success rates of central venous catheter placement (CVCP) in dogs using electrocardiograph (ECG)‐guided and external landmark (‘blind’) techniques. To report success rates determined retrospectively of CVCPs in dogs using external landmarks at a tertiary referral institution. Study design Prospective blinded comparison of techniques. Retrospective analysis of case records. Animals Adult Beagles weighing 11.9 ± 2.6 kg were used in the experimental group (n = 38). Various breeds of dogs were in the retrospective clinical group (n = 33). Methods Laboratory dogs were anesthetized and CVCPs were placed using a modified Seldinger technique. Catheter tip position was first based on external landmarks and then the catheter was repositioned using an ECG‐guided placement. The ECG‐guided technique used the V‐lead with the positive electrode attached to the guide wire. Catheter placement was determined by moving the catheter cephalad and caudad to the point of maximum p‐wave amplitude and then withdrawing the catheter 1–2 cm from this point. Catheter position with each technique was determined using a lateral thoracic radiograph. Retrospective data were collected from the medical records of dogs that had CVCPs using anatomical landmarks and corresponding thoracic radiographs. Results The number of successful CVCP attempts was the same for both prospective groups (21/38). There was no statistically significant difference in success between the ECG‐guided technique and the blind technique. From the retrospective investigation 10/33 of the cases that fit the criteria had correct CVCPs. Conclusions and clinical relevance The odds of correctly placing a central venous catheter by ECG‐guidance were the same as the external landmark technique. The ECG‐guided technique may be useful in situations where external landmarks are not readily available. 相似文献
476.
Renaud Ioos Tadeusz Kowalski Claude Husson Ottmar Holdenrieder 《European journal of plant pathology / European Foundation for Plant Pathology》2009,125(2):329-335
Chalara fraxinea is a fungus currently threatening ash trees (Fraxinus excelsior) in several European countries. This emerging pathogen was assigned to the EPPO’s alert list and therefore accurate detection and identification tools are needed. Because of its slow growth rate on agar media and the frequent presence of fast-growing saprotrophic fungi within the host tissue, classical isolation techniques are time-consuming and sometimes inefficient. In this study, we used species-specific polymorphisms observed within the internal transcribed spacer region to design a primer pair and a dual-labelled probe to be used in a real-time PCR assay for the detection of C. fraxinea. The test proved to be specific, based on in silico and in vitro assessments, and could detect as little as 20 fg of C. fraxinea DNA. A protocol was developed in order to detect the pathogen directly in plant tissue and proved to be more efficient and rapid than isolation on agar plates. This new tool should be useful both for monitoring and to conduct epidemiology research on this emerging pathogen. 相似文献
477.
Reciprocal recurrent selection (RRS) exploits the genetic complementarity of dura populations of palms with a small number of large bunches and tenera/pisifera group of palms with large number of small bunches. An extra phase was introduced to RRS just after the second cycle of selection
where outstanding dura derived from (DA3D × DA5D) combinations of the second cycle were self-pollinated for seed production. Best palms based on
the phenotype were selected and crossed with pisifera of second cycle offspring of LM2T. [(DA3D × DA5D) self-pollinated × LM2T self-pollinated] progenies were field tested at
La Dibamba (Cameroun) from 1987 to 1997. They were precocious with regard to the three-first years’ bunch yields (13.16–15.77 t/ha).
Homogeneity for all bunch yield components and homogeneity for vertical growth were illustrated by low values of the variation
coefficient (5.75–7.75%). The oil yield was 107% of the control against 115% from [(DA3D × DA5D) × LM2T self-pollinated] progenies
of the second cycle of RRS, mostly due to poor mesocarp to fruit and poor oil to mesocarp ratios which led to a low oil extraction
rate. The extra selection phase led mainly to homogenisation of progenies but also reduced the fruit quality. However, three
progenies whose average oil yield represented 115% of the control (4.87 t/ha) in addition to their precocity can be released
to oil palm growers. The extension of RRS did not fully meet expectations and poses the problem of its reliability. 相似文献
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