Mapping aboveground biomass by integrating geospatial and forest inventory data through a k-nearest neighbor strategy in North Central Mexico

As climate change negotiations progress,monitoring biomass and carbon stocks is becoming an important part of the current forest research.Therefore,national governments are interested in developing forest-monitoring strategies using geospatial technology.Among statistical methods for mapping biomass,there is a nonparametric approach called k-nearest neighbor(kNN).We compared four variations of distance metrics of the kNN for the spatially-explicit estimation of aboveground biomass in a portion of the Mexican north border of the intertropical zone.Satellite derived,climatic,and topographic predictor variables were combined with the Mexican National Forest Inventory(NFI)data to accomplish the purpose.Performance of distance metrics applied into the kNN algorithm was evaluated using a cross validation leave-one-out technique.The results indicate that the Most Similar Neighbor(MSN)approach maximizes the correlation between predictor and response variables(r=0.9).Our results are in agreement with those reported in the literature.These findings confirm the predictive potential of the MSN approach for mapping forest variables at pixel level under the policy of Reducing Emission from Deforestation and Forest Degradation(REDD+).     

Application of different doses of calcium hydroxide in the farming shrimp Litopenaeus vannamei with the biofloc technology (BFT)

The reduction in alkalinity and pH occurs due to the consumption of inorganic carbon by bacteria present in the biofloc. The objective of the study was to evaluate the effects of different doses of calcium hydroxide on the water quality and growth performance of the Litopenaeus vannamei in a biofloc system. The experiment consisted of four treatments with three repetitions for each treatment: Control treatment (TC), in which the pH maintained above 7.2 due to the application of 0.05 g L^?1 of calcium hydroxide, and treatments T10, T20 and T40, in which daily doses of calcium hydroxide equivalent to 10, 20 and 40 % of the total amount of feed offered to the shrimp, respectively, were added to the environment. Twelve experimental units (150 L) were stocked with 85 juveniles of L. vannamei (0.18 ± 0.06 g), corresponding to a density of 425 shrimp m^?3, and cultivated for 56 days. The values of alkalinity and pH for treatments TC and T10 were similar and significantly lower (p < 0.05) than those for treatments T20 and T40, which differed (p < 0.05) between each other. In terms of growth performance, TC, T10 and T20 performed significantly better (p < 0.05) than T40. There were no significant differences (p > 0.05) in the survival rates. The results obtained indicate that doses of 0.05 g L^?1 of calcium hydroxide or daily applications between 10 and 20 % of the total amount of feed offered to the shrimp can be used for the correction of alkalinity and pH.     

Iron Tolerance in Calla Lilies (Zantedeschia aethiopica)

Excess iron in soils affects many agricultural areas worldwide, causing great losses in cultivated plants particularly in waterlogged environments. Plants, such as the calla lily (Zantedeschia aethiopica), which grows in such wetlands, have been widely used for the treatment of wastewater. White calla lily plants were grown hydroponically from seeds in a greenhouse in Tunja, Colombia, under either of three different levels of iron (0, 100 or 200 ppm Fe) to evaluate the plant’s tolerance to excess iron. The total dry mass production, water uptake, water use efficiency (WUE), dry matter partitioning and root to shoot ratio were recorded four months after transplanting. The dry mass production per plant decreased as the iron level increased. Although water uptake decreased inversely proportional to the iron level, the WUE was not affected by iron. On the other hand, iron affected dry matter partitioning to the plant organs, accumulating more dry matter in the roots than in the shoot with higher iron levels. Hence, we suggest that the calla plant is moderately tolerant to excess iron and would be appropriate for the phytoremediation of wetlands contaminated with this metal.     

Can spleen aspirations be safely used for the parasitological diagnosis of canine visceral leishmaniosis? A study on assymptomatic and polysymptomatic animals

The purpose of this study was to evaluate the safety of spleen aspiration as a sampling technique for the parasitological detection by culture and microscopy of Leishmania (chagasi) infantum. Two hundred and nine domiciled dogs from an endemic area for visceral leishmaniasis in Bahia State, Brazil, were studied. Most dogs (87%) were seropositive for anti-L. chagasi antibodies by ELISA. Clinical signs of disease were recorded and the animals monitored during and after spleen puncture in order to detect possible complications associated with the procedure. From a total of 257 splenic punctures in the 209 animals, only three minor events occurred, with no significant consequence for the animals and no association with risk factors. Leishmania was isolated from 149/180 (83%) seropositive dogs, and from 6/26 (23%) seronegative animals. The procedure did not cause adverse side effects or unnecessary suffering and confirmed the diagnosis in a large percentage of dogs. We conclude that spleen aspiration can be considered an effective and safe procedure for the definitive diagnosis of canine visceral leishmaniosis.     

Comparison of ozone and UV-C treatments on the postharvest stilbenoid monomer, dimer, and trimer induction in var. 'Superior' white table grapes

Postharvest treatment of seedless white table grapes (var. 'Superior') with different gas ozone concentrations (3.88 and 1.67 g/h) for 1, 3, and 5 h induced an increase in stilbenoid biosynthesis [trans-resveratrol, piceatannol, and viniferinas (resveratrol dehydrodimers and dehydrotrimers)] during storage at 22 degrees C and 95% relative humidity. The maximal resveratrol concentration was reached after 2 days of storage, and this amount was similar to that induced by optimized UV-C treatments (1 min, 510 W, 40 cm). Although similar resveratrol concentrations accumulated in grapes after both UV-C and O3 treatments (maximum ozone production and time), the ozone treatment was more efficient in inducing viniferins accumulation in grape berries. A sequence in the biosynthesis of stilbenoids was observed, starting with the resveratrol monomer, continuing with the resveratrol dehydrodimers epsilon-viniferin and delta-viniferin, and ending with four different resveratrol dehydrotrimers. These trimers were different from alpha-viniferin, a trimer previously reported to be induced in grapes after biotic and abiotic stresses. Two alpha-viniferin isomers were also detected in the ozone-treated grapes, although at very low concentrations that prevented their quantification.     

Determination of fluoroquinolones in milk samples by postcolumn derivatization liquid chromatography with luminescence detection

A liquid chromatography (LC) method with luminescence detection for the determination of eight quinolone antibiotics is reported. The system encompasses three consecutive steps: (a) chromatographic separation using reverse-phase mode (RP-LC), (b) postcolumn derivatization reaction, and (c) luminescence detection by monitoring fluorescence (FL) and time-resolved (TR) signals. The derivatization step is based on the reaction between quinolones and terbium(III) to form luminescent chelates, which were determined at lambda(ex) 340 and lambda(em) 545 nm (FL mode) or at lambda(ex) 281 and lambda(em) 545 nm (TR mode). Dynamic ranges of the calibration graphs, obtained with standard solutions of analytes and FL and TR modes, respectively, were 190-3500 and 316-2000 ng mL-1 for marbofloxacin, 8-3500 and 8.1-1500 ng mL-1 for ciprofloxacin, 6.2-3500 and 13-1500 ng mL-1 for danofloxacin, 7.4-3500 and 8.4-1500 ng mL-1 for enrofloxacin, 14-3500 and 20-2000 ng mL-1 for sarafloxacin, 12.5-3500 and 13.9-1200 ng mL-1 for difloxacin, 7.6-3500 and 13-3000 ng mL-1 for oxolinic acid, and 9-2000 and 130-3000 ng mL-1 for flumequine. Limit of detection values obtained using FL and TR modes, respectively, were 60 and 95 ng mL-1 for marbofloxacin, 2 and 2.4 ng mL-1 for ciprofloxacin, 1.9 and 3.9 ng mL-1 for danofloxacin, 2.2 and 2.5 ng mL-1 for enrofloxacin, 3.8 and 7 ng mL-1 for sarafloxacin, 4 and 4.2 ng mL-1 for difloxacin, 2.3 and 4 ng mL-1 for oxolinic acid, and 2.7 and 40 ng mL-1 for flumequine. The precision was established at two concentration levels of each analyte and expressed as the percentage of relative standard deviation with values ranging between 1.9 and 7.8%. The validation procedure for the analysis of samples was carried out using European Community recommendations, and the decision limit and detection capability were calculated for bovine whole milk. The method was applied to whole, semiskimmed, and skimmed milk samples spiked with the target analytes, and the recoveries ranged between 93.3 and 106.0%.     

Pharmacokinetics of difloxacin after intravenous, intramuscular, and intragastric administration to horses

OBJECTIVE: To study the pharmacokinetics of difloxacin (5 mg/kg) following IV, IM, and intragastric (IG) administration to healthy horses. ANIMALS: 6 healthy mature horses. PROCEDURES: A crossover study design with 3 phases was used (15-day washout periods between treatments). An injectable formulation of difloxacin (5%) was administered IV and IM in single doses (5 mg/kg); for IG administration, an oral solution was prepared and administered via nasogastric tube. Blood samples were collected before and at intervals after each administration. A high-performance liquid chromatography assay with fluorescence detection was used to determine plasma difloxacin concentrations. Pharmacokinetic parameters of difloxacin were analyzed. Plasma creatine kinase activity was monitored to assess tissue damage. RESULTS: Difloxacin plasma concentration versus time data after IV administration were best described by a 2-compartment open model. The disposition of difloxacin following IM or IG administration was best described by a 1-compartment model. Mean half-life for difloxacin administered IV, IM, and IG was 2.66, 5.72, and 10.75 hours, respectively. Clearance after IV administration was 0.28 L/kg.h. After IM administration, the absolute mean +/- SD bioavailability was 95.81 +/- 3.11% and maximum plasma concentration (Cmax) was 1.48 +/- 0.12 mg/L. After IG administration, the absolute bioavailability was 68.62 +/- 10.60% and Cmax was 0.732 +/- 0.05 mg/L. At 12 hours after IM administration, plasma creatine kinase activity had increased 7-fold, compared with the preinjection value. CONCLUSIONS AND CLINICAL RELEVANCE: Data suggest that difloxacin is likely to be effective for treating susceptible bacterial infections in horses.