78 research outputs found

    Early Growth in Weight of Kemp\u27s Ridley Sea Turtles (Lepidochelys kempii) in Captivity

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    Growth in individual weight (w, kg) of Kemp’s ridley sea turtles (Lepidochelys kempii) in captivity was described for 15 year-classes (1978-1992) of turtles between ages (t) 0.17 to 1.22 yr, using In linear regression: Inw = lnc + dt1/2, where Inc is the intercept and d is the slope (growth rate index). There was significant (P \u3c 0.001) heterogeneity in d among year-classes, with slowest growth (d = 3.798) exhibited by the 1983 year-class and fastest growth (d = 6.929) by the 1985 year-class, but there was no significant trend in d (P = 0.307) over year-classes. The variance of residuals from regression, s2reg, ranged from 0.2032 for the 1978 year-class to 0.0075 for the 1992 year-class, and showed a significant (P = 0.0001) logarithmic decrease over the year-classes. This decline in variation among individuals was probably due to a a shift toward sex ratios dominated by one sex (females), improvements in rearing facilities, year-around control of seawater temperature which reduced disease incidence, improved diet, and reduced feeding levels. The relationship between w and scl (straight carapace length) was also described

    Lippia citriodora (verbascoside) extract supplementation: Effect on rabbit semen quality in vivo and in vitro

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    Verbascoside, the main component of Lippia citriodora extract, is one of the most powerful free radical scavengers exhibiting a wide biological activity. In in vivo study 20 adult New Zealand white rabbit bucks were divided into two homogeneous groups, one control (CON) and one verbascoside-supplemented (0.1%) in feed mixture (EXP) and later in vitro effects of verbascoside on the motility aspects of rabbit spermatozoa were analysed. The spermatozoa concentration, ejaculate volume, spermatozoa motility, progressive motility, distance parameters, velocity parameters and type of spermatozoa movement were negatively affected by Lippia citriodora leaves extract after the first 4 weeks of dietary treatment, till the end of experiment (8 weeks). Four weeks after the suspension of feed additive supplementation, all spermatozoa traits values returned to the normality, and in line with CON group. For in vitro findings, ejaculates from 10 male New Zealand white bucks were collected using an artificial vagina. Then it was diluted in physiological saline solution containing different concentrations of verbascoside at the concentration of 0, 0.0024, 0.0219, 0.157, 120.0 mg/ml (Ctrl, VB1, VB2, VB3, VB4 groups, respectively), using a dilution ratio of 1: 4. The obtained data proved that verbascoside at the concentration of 0.0024 and 0.0219 mg/ml had no adverse effect on spermatozoa. Additionally, we found that verbascoside at higher concentrations (0.157 and 120.0 mg/ml) significantly altered all the motility parameters analysed in the experiment. In conclusion a possible negative effect of verbascoside supplementation into feed mixture (0.1%) on semen quality parameters in rabbit bucks as well as in vitro can be stated, obviously considering that target organs of antioxidant activities of phenylpropanoid glycosides are various. In addition it has to be emphasized that the extract showed a reversible action, since the semen traits of treated animals returned to the normality after the dietary administration period

    FACTORS AFFECTING THE FREQUENCY OF ONLINE SHOPPING OF YOUNG CONSUMERS IN THE POST-COVID19 ERA

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    Background: Understanding of drivers of online shopping is crucial in today’s digitized world. The COVID-19 pandemic highly influenced young consumers shopping behavior and rapidly raised their preference for online shopping. Aims: The aim of this paper was to investigate which factors affect the frequency of young consumers’ online shopping in the post-pandemic era. Methods: The data were evaluated by application of the Generalized linear model. Sample: The primary data were collected through a self-administered questionnaire with 635 respondents. Results: The results showed that the perceived e-trust and the usage of social media (expressed through factors such as frequency of use and promotion on social media) influence the frequency of online shopping of these consumers. The research also revealed that males tend to shop online more than females. Conclusions: Social media usage, e-trust and promotion on social media proved as significant factors affecting the frequency of online shopping of young consumers. The factor of gender showed up significant too. Implications: It is important to differentiate the contents of the messages on social media based on gender and the customer segments to whom the communication and promotions on social media are addressed

    R&D Structure in a Changing World

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    Concentration, distribution, and fractionation of metals in the filter material of 29 bioretention facilities: a field study

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    Pollutant loads stemming from anthropogenic activities conveyed in urban stormwater runoff contribute to the impairment of downstream water bodies. Cities and municipalities are increasingly turning toward green infrastructure stormwater control measures to treat pollutants at the source of runoff. One example of these technologies is bioretention, which is commonly applied for stormwater treatment in urban areas due to its demonstrated effectiveness in removing various pollutants from water, including sediment, nutrients (e.g., N and P), and metals. As metals are mainly removed by filtration or adsorption to soil particles, the filter media is important for metal removal in bioretention. However, the capacity to remove metals through adsorption by bioretention media is finite; thus, the media may need to be replaced and disposed of after maintenance or at the end of its operational lifespan. Pollutant accumulation in bioretention media has the potential to approach toxicity thresholds, which may introduce complexities for safe handling and disposal. To fully capture the potential challenges associated with metals accumulation in media over time, it is important to understand the accumulation processes and mobility of metals in bioretention facilities as they age. Although several studies have investigated metal accumulation and distribution in bioretention media, few have assessed metal mobility by fractionation using sequential extraction methods in older (i.e., >7 years) facilities. In November 2019, we conducted a comprehensive field study of older facilities in Ohio, Michigan, and Kentucky (USA) to improve the understanding of the accumulation processes and metal mobility in bioretention. In this study, concentrations of several metals (i.e., Cr, Cu, Ni, Pb, and Zn) were analyzed in samples of filter material from 29 bioretention sites in operation for 7–16 years. Except for Cd, all metals were found in all samples. Metals accumulation was clear with highest concentrations found in the top (0–5 cm) layer of the filter material, attributable to the filtration of particles percolating through the media profile. Lower concentrations were observed in deeper (i.e., >10 cm) layers of the bioretention media. The fractionation showed that the metals of interest were present at high levels with a risk of leaching over time, among which Cd, Zn, and Pb were suggested to be mobile from the filter material during precipitation. Thus, there is a potential risk of leakage from filter material or sediment removed from biofilters, e.g., during maintenance and disposal. The results of principal component analysis indicated specifically correlations between metal concentrations and the filter material soil texture including the organic matter content. These results contribute to improved design and operation and suggest regular maintenance to reduce long-term risks associated with the accumulation of metals in bioretention and similar urban stormwater treatment facilities. Since most metals are trapped in the top layer of the filter it may be enough to remove only the top layer. However, metal fractionation should be considered when handling the material
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