Estimating Population Growth Rate From Capture–Recapture Data in Presence of Capture Heterogeneity

The direct estimation and modeling of population growth rate from capture–recapture data has now seen a number of applications. However, the original model cannot accommodate heterogeneous capture probabilities. While studying a population of small mammals Peromyscus maniculatus, we became concerned that the peak of population size may be estimated too late in the year because of heterogeneous catchability. Hence, we developed a variation of the original model with a finite number of catchability classes. The results obtained with the new model are more in agreement with the known biology of this population. A bibliographic appendix and computer code are available online.     

Comparison of Fick and thermodilution cardiac output determinations in standing horses

The Fick and thermodilution (TD) methods are two currently popular techniques for determination of cardiac output (CO) in adult horses. To our knowledge, a comparison of these two techniques has not been reported. Six healthy, resting, fit, adult horses of either sex and weighing 516.5+/-33.2 kg (mean+/-SD) were instrumented to enable measurement of cardiac output. Resting CO was determined by the Fick method and by thermodilution while the horses stood quietly in the stocks. Fick and thermodilution CO measurements were repeated under conditions of increased cardiac output achieved with the use of a dobutamine infusion (5 microg kg(-1) min(-1), IV), and again under conditions of decreased CO induced by administration of xylazine (0.5 mg/kg, IV). Fick and thermodilution cardiac outputs were compared using Bland-Altman analysis for repeated measures. The mean of the differences+/-1.96SD (bias and precision) between the two techniques was 1.88+/-24.17 L/min. Variability between measurements with the two techniques was decreased to 3.41+/-46.78 mL kg(-1) min(-1) when CO was normalized for body size by calculation of cardiac index.     

Effect of ENSO on the distribution and concentration of catches and reproductive activity of anchovy Engraulis ringens in northern Chile

Anchovy makes up 90% of pelagic fishery catches in northern Chile. For the present work, anchovy (Engraulis ringens, Jenyns 1842) catches between 1997 and 2016 were analyzed to determine changes in distribution, concentration, and reproductive behavior before, during, and after ENSO events, using spatial indexes: gravity center (GC), inertia, coverage (CI), Gini index, and gonadosomatic index (GI). At the start of ENSO, anchovy catches increased and concentrated along the coast (rising Gini index), while CI decreased. During ENSO, Gini decreased, registering a southward displacement of the GC and smaller catches. In the long run, anchovy occupied lesser area (<CI) starting from 2008, concentrating in coastal areas. It developed a size structure composed mainly of specimens smaller than 17.0 cm. In addition, specimens < 12.0 cm were positively correlated with thermal anomalies, CI and MEI, reaching more than 60% of the catches during the 1997–1998 and 2015–2016 ENSO cycles. Results suggest that the warm phase of ENSO alters the anchovies’ reproductive activity, delaying its onset up to 4 weeks, and reducing GI intensity to 50%, due to increased participation in the reproductive process of individuals 12.0–13.5 cm. Therefore, large‐scale environmental processes, such as ENSO, significantly affect size structure and contribute to reduction of occupied area and higher reproductive activity of small‐size anchovies.     

Cuticular calcium penetration is directly related to the area covered by calcium within droplet spread area

Calcium penetration from salt solutions of calcium chloride and calcium acetate was measured through isolated tomato fruit (Solanum lycopersicum L., cultivar ‘Panovy’) cuticles after 4, 24, and 48 h. Droplet spread area (volume = 1 μL) and the area ultimately covered with calcium were determined with a scanning electron microscope which has an integrated energy dispersive X-ray microanalysis system. An ethoxylated rapeseed oil surfactant (RSO 5) was used for inducing different degrees of droplet spread and together with different calcium concentrations of the solutions to vary the concentration gradient in the penetration experiments. As a rule, penetration of calcium from CaCl₂ was higher than that of Ca(CH₃COO)₂. The addition of RSO 5 to salt solutions resulted in enhanced calcium penetration in comparison to unformulated solutions. However, extending penetration time from 4 to 48 h predominantly did not enhance the penetrated calcium amount significantly. Droplet spread area was enhanced up to 4-fold after adding RSO 5, whereas the area ultimately covered with calcium did not exceed twice as much. This resulted in lower percentage area covered by calcium in droplet footprints from formulated solutions in comparison to solutions without addition of RSO 5. Correlation analyses showed that penetration was not related to droplet spread area but significantly correlated with the area covered by calcium. These observations were true for unformulated calcium salts as well as for calcium solutions with addition of RSO 5. Therefore, the area ultimately covered with calcium or even other xenobiotics within a droplet footprint should be considered in developing mathematical models to simulate active ingredient (a.i.) penetration.     

Effect of incubation temperature on the embryonic development and yolk‐sac larvae of the Pacific red snapper Lutjanus peru (Nichols & Murphy, 1922)

The effect of incubation temperature on embryonic development and yolk‐sac larva of the Pacific red snapper Lutjanus peru were evaluated by testing the effect of 26, 28 and 30°C, as this is the natural thermal interval reported during the spawning season of Pacific red snapper in the Gulf of California, Mexico. Sixteen developmental stages were observed. The incubation temperature affected the rate of development and time to hatching, being shorter at 30 than at 26°C, but no significant effect (P < 0.05) on larval length at hatching was registered. The depletion rate of yolk sac and oil globule was affected by incubation temperature particularly during the first 12 h post hatching (hph). At the end of the experiment (48 hph), significantly (P < 0.05) larger larvae were recorded at 26°C (TL = 3.22 ± 0.01 mm) than at 28° (TL = 3.01 ± 0.02 mm) and 30°C (TL = 2.97 ± 0.05 mm). Incubation of newly fertilized eggs at 26°C produces larger larvae, which may help to improve feeding efficiency and survival during first feeding.     

Understanding overbidding: using the neural circuitry of reward to design economic auctions

We take advantage of our knowledge of the neural circuitry of reward to investigate a puzzling economic phenomenon: Why do people overbid in auctions? Using functional magnetic resonance imaging (fMRI), we observed that the social competition inherent in an auction results in a more pronounced blood oxygen level-dependent (BOLD) response to loss in the striatum, with greater overbidding correlated with the magnitude of this response. Leveraging these neuroimaging results, we design a behavioral experiment that demonstrates that framing an experimental auction to emphasize loss increases overbidding. These results highlight a role for the contemplation of loss in understanding the tendency to bid "too high." Current economic theories suggest overbidding may result from either "joy of winning" or risk aversion. By combining neuroeconomic and behavioral economic techniques, we find that another factor, namely loss contemplation in a social context, may mediate overbidding in auctions.     

Retrospective and prospective studies of transmissible viral proventriculitis in broiler chickens in Brazil

We investigated the occurrence and pathologic findings of transmissible viral proventriculitis (TVP) associated with the chicken proventricular necrosis virus (CPNV) in commercial broiler chickens in southeastern Brazil. Seventy-three broilers, 25–36 d old, with a history of reduced growth, were referred to our veterinary pathology services from 2013 to 2017. Broilers were clinically examined, weighed, and euthanized for postmortem examination. Broilers of different ages with proventricular histologic lesions were positive for CPNV by RT-PCR; however, the intensity of histologic lesions was higher among 33-d-old animals, and viral RNA detection was more frequent among those that were 28 d old. In the proventriculi of 35 of 73 (48%) broilers, lesions were characterized by glandular epithelial necrosis, lymphoplasmacytic and histiocytic infiltrates, and metaplasia of glandular epithelium to ductal epithelium. In 24 of 73 (36%) broilers with histologic TVP-compatible lesions, CPNV was detected by RT-PCR for the viral protein 1 (VP1) gene. Broilers with histologic lesions were lighter than expected compared to the Cobb 500 standard weight. TVP has not been reported previously in broiler chickens in Brazil, to our knowledge.     

Chemical composition, nutritive value, and toxicology evaluation of Mexican wild lupins.

The nutrient composition, toxic factors content, and nutritional and toxicological value of Lupinus splendens, L. rotundiflorus, L. elegans, L. simulans, L. exaltatus, L. reflexus, and L. madrensis species from Mexico were analyzed. The seeds of these species were a good source of protein. All the species showed a high lysine and tryptophan content, though sulfur amino acids were limiting. Cyanogenic glycosides were absent, and lectins, trypsin inhibitors, and tannins were present in low concentrations. Lupanine was the major alkaloid in almost all the samples, although sparteine was the major alkaloid in Lupinus reflexus (26.63 mg/g of sample). Cytisine was not found in any of the studied lupins. L. reflexus showed the highest acute toxicity, and L. elegans exhibited no toxicity as evaluated using a mice model. The alkaloid was reduced by hot-water extraction. The protein efficiency ratio in water-debittered seeds was relatively poor (1.1-1.5). These results suggest that the wild lupins studied represent a potential protein supply, and they could be domesticated and used for animal feed if the alkaloids were eliminated and the protein was supplemented with methionine, or if the lupins were used in mixture with cereals.