535 research outputs found
Effects of hatching timing on red-eyed treefrog tadpoles: relative vulnerability varies among predators but not with hatchling age-structure, growth varies with the presence of more vulnerable tadpoles [poster]
In Gamboa, Panama, undisturbed red-eyed treefrog embryos typically hatch at age 6 days, but they can hatch as early as 4 days if attacked by egg predators. Early hatchlings are less developed and more vulnerable to predatory shrimp and fish. Here we assess the effect of hatching timing on risk of predation by three common insects, with different foraging styles, that prey on red-eyed treefrog larvae. Further, we examine whether the consequences of hatching early vary with the presence of later-hatched tadpoles. We induced hatching at 4 and 6 days and exposed tadpoles to giant water bugs or aeshnid or libellulid dragonfly larvae over 24 hrs, quantifying tadpole behavior and mortality. We used substitutive designs with three treatments: early hatched, late hatched and mixed hatching ages. In no case did presence of the other age class alter mortality. Hatching age did not affect libelullid predation, which was low in both cases. Early-hatched tadpoles had higher mortality than late hatchlings with water bugs, which move throughout the water column. In contrast, early hatchlings had lower mortality than late hatchlings with aeshnids, which cue strongly on movement. Late-hatched tadpoles were more active than early hatchlings, and movement was reduced in the presence of aeshnids. Combining across this and previously published studies, early hatchlings are more vulnerable than late hatchlings to most (3/5) predators. Variation in relative, age-specific hatchling vulnerability to predators with different foraging styles is consistent with developmental changes in tadpole behavior
The Cost of Hatching Early: Vulnerability and Exposure to Predators [poster]
Arboreal red-eyed treefrog embryos can hatch prematurely in response to egg predators. Induced early hatchlings face aquatic predators when less developed and for longer than do later hatchlings; both factors may alter survival through the high-risk early larval period. Prior work focused on developmental effects of induced hatching. In 24 h trials, less developed hatchlings were more vulnerable to three aquatic predators (shrimp, fish, water bugs) but had similar or better survival than full-term hatchlings with libellulid and aeschnid dragonfly nymphs. However, it is unknown how developmental effects and duration of exposure to predators combine to create the net effect of early hatching. Here we measured costs of early hatching over a 72 h period, from first hatching competence past peak spontaneous hatching. Embryos hatched at age 4 or 6 days were exposed to water bugs, aeshnids, or libellulids. Early-hatched tadpoles suffered higher mortality than late hatchlings with all three predators. The longer exposure of early hatchlings to aquatic predators reversed their initial phenotypic advantage with aeshnids and revealed a cost of early hatching with libellulids where none was apparent from phenotypes alone. In other experiments, early-hatched tadpoles reared without predators grew more quickly than those reared with predators cues, which grew more quickly than age-matched embryos, revealing phenotypic effects of both predator cues and the egg vs. aquatic environment. Nonetheless, any potential benefits of predator-induced phenotypes on tadpole survival were insufficient to compensate for the increased duration of predator exposure that is a consequence of hatching early.
From the Conference Program at http://www.sicb.org/meetings/2011/schedule/abstractdetails.php3?id=23
Genomics-Integrated Breeding for Carotenoids and Folates in Staple Cereal Grains to Reduce Malnutrition
Globally, two billion people suffer from micronutrient deficiencies. Cereal grains provide
more than 50% of the daily requirement of calories in human diets, but they often
fail to provide adequate essential minerals and vitamins. Cereal crop production in
developing countries achieved remarkable yield gains through the efforts of the Green
Revolution (117% in rice, 30% in wheat, 530% in maize, and 188% in pearl millet).
However, modern varieties are often deficient in essential micronutrients compared
to traditional varieties and land races. Breeding for nutritional quality in staple cereals
is a challenging task; however, biofortification initiatives combined with genomic tools
increase the feasibility. Current biofortification breeding activities include improving rice
(for zinc), wheat (for zinc), maize (for provitamin A), and pearl millet (for iron and zinc).
Biofortification is a sustainable approach to enrich staple cereals with provitamin A,
carotenoids, and folates. Significant genetic variation has been found for provitamin A
(96–850 mg and 12–1780 mg in 100 g in wheat and maize, respectively), carotenoids
(558–6730 mg in maize), and folates in rice (11–51 mg) and wheat (32.3–89.1 mg)
in 100 g. This indicates the prospects for biofortification breeding. Several QTLs
associated with carotenoids and folates have been identified in major cereals, and the
most promising of these are presented here. Breeding for essential nutrition should be
a core objective of next-generation crop breeding. This review synthesizes the available
literature on folates, provitamin A, and carotenoids in rice, wheat, maize, and pearl
millet, including genetic variation, trait discovery, QTL identification, gene introgressions,
and the strategy of genomics-assisted biofortification for these traits. Recent evidence
shows that genomics-assisted breeding for grain nutrition in rice, wheat, maize, and
pearl millet crops have good potential to aid in the alleviation of micronutrient malnutrition
in many developing countries
Risk assessment based on indirect predation cues: revisiting fine-grained variation
To adaptively express inducible defenses, prey must gauge risk based on indirect cues of predation. However, the information contained in indirect cues that enable prey to fine-tune their phenotypes to variation in risk is still unclear. In aquatic systems, research has focused on cue concentration as the key variable driving threat-sensitive responses to risk. However, while risk is measured as individuals killed per time, cue concentration may vary with either the number or biomass killed. Alternatively, fine-grained variation in cue, that is, frequency of cue pulses irrespective of concentration, may provide a more reliable signal of risk. Here, we present results from laboratory experiments that examine the relationship between red-eyed treefrog tadpole growth and total cue, cue per pulse, and cue pulse frequency. We also reanalyze an earlier study that examined the effect of fine-grained variation in predator cues on wood frog tadpole growth. Both studies show growth declines with increasing cue pulse frequency, even though individual pulses in high-frequency treatments contained very little cue. This result suggests that counter to earlier conclusions, tadpoles are using fine-grained variation in cue arising from the number of predation events to assess and respond to predation risk, as predicted by consumer–resource theory.ECU Open Access Publishing Support Fund;
National Science Foundation Grant Numbers: 0716923, 071722
Genetic improvement of chickpea for western Canada
Non-Peer ReviewedThe chickpea crop has experienced a roller-coaster ride over the past decade in western Canada. Production rose rapidly in the late 1990’s, followed by dramatic declines in the past two years. Instability can be attributed to many factors including commodity prices, erratic weather patterns, Ascochyta blight and late maturity. This paper summarizes current research on genetic improvement of chickpea at the University of Saskatchewan, with particular emphasis on efforts to improve Ascochyta blight resistance and to develop varieties with earlier maturity. Under ‘average’ weather conditions, chickpea remains an excellent nitrogen-fixing crop for the Brown and Dark Brown soil zones
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Getting it right: a model for compliance assessment
Compliance is important for organisations but models and tools to aid understanding of compliance behaviour is limited. This paper argues that the understanding of the interaction between subjects and objects and their intention to comply with requirements of rules and regulations may be a predictor of compliance behaviour. Thus, a Conceptual Compliance Assessment Model (CAM) is developed by extension of Technology Acceptance Model and Activity theory for assessment of compliance behaviour. Data collected and evaluated showed that the awareness and understanding of the mediational tool is critical in realizing the outcome. It also showed that other factors like the perceived usefulness, perceived ease of use, the community and the management set up also affected compliance behaviour. Essentially, the use of CAM will be useful in assessing the compliance activities of subjects which may aid in formulation of behaviour support systems to improve compliance behaviour
Cyber security fear appeals:unexpectedly complicated
Cyber security researchers are starting to experiment with fear appeals, with a wide variety of designs and reported efficaciousness. This makes it hard to derive recommendations for designing and deploying these interventions. We thus reviewed the wider fear appeal literature to arrive at a set of guidelines to assist cyber security researchers. Our review revealed a degree of dissent about whether or not fear appeals are indeed helpful and advisable. Our review also revealed a wide range of fear appeal experimental designs, in both cyber and other domains, which confirms the need for some standardized guidelines to inform practice in this respect. We propose a protocol for carrying out fear appeal experiments, and we review a sample of cyber security fear appeal studies, via this lens, to provide a snapshot of the current state of play. We hope the proposed experimental protocol will prove helpful to those who wish to engage in future cyber security fear appeal research
Quasi-free Compton Scattering from the Deuteron and Nucleon Polarizabilities
Cross sections for quasi-free Compton scattering from the deuteron were
measured for incident energies of 236--260 MeV at the laboratory angle -135
degrees. The recoil nucleons were detected in a liquid-scintillator array
situated at 20 degrees. The measured differential cross sections were used,
with the calculations of Levchuk et al., to determine the polarizabilities of
the bound nucleons. For the bound proton, the extracted values were consistent
with the accepted value for the free proton. Combining our results for the
bound neutron with those from Rose et al., we obtain one-sigma constraints of
alpha_n = 7.6-14.0 and beta_n = 1.2-7.6.Comment: 4 pages, 3 figures, accepted in PR
Mapping Quantitative Trait Loci for Carotenoid Concentration in Three F2 Populations of Chickpea
Three F2 populations derived from crosses between
cultivars with green and yellow cotyledon colors were used to identify quantitative trait loci (QTLs) associated with carotenoid components in chickpea (Cicer arietinum L.) seeds developed by the Crop Development Centre (CDC). Carotenoids including violaxanthin, lutein, zeaxanthin, b-cryptoxanthin, and b-carotene were assessed in the F2:3 seeds via high-performance liquid chromatography (HPLC). In the ‘CDC Jade’ × ‘CDC Frontier’ population, 1068 bin markers derived from the 50K Axiom CicerSNP array were mapped onto eight linkage groups (LGs). Eight QTLs, including two each for b-carotene and zeaxanthin and
one each for total carotenoids, b-cryptoxanthin, b-carotene, and violaxanthin were identified in this population. In the ‘CDC Cory’ × ‘CDC Jade’ population, 694 bin markers were mapped onto eight LGs and one partial LG. Quantitative trait loci for b-cryptoxanthin, b-carotene, violaxanthin, lutein, and total carotenoids were
identified on LG8. A map with eight LGs was developed from 581 bin markers in the third population derived from the ‘ICC4475’ × ‘CDC Jade’ cross. One QTL for b-carotene and four QTLs, one each for b-cryptoxanthin, b-carotene, lutein, and total carotenoids, were identified in this population. The highest phenotypic variation explained by the QTLs was for b-carotene, which ranged from 58
to 70% in all three populations. A major gene for cotyledon color was mapped on LG8 in each population. A significant positive correlation between cotyledon color and carotenoid concentration was observed. Potential candidate genes associated with carotenoid components were obtained and their locations on the chickpea genome are presented
E-government adoption: A cultural comparison
This is the author's accepted manuscript. The final published article is available from the link below. Copyright @ Springer Science + Business Media, LLC 2008.E-government diffusion is an international phenomenon. This study compares e-government adoption in the U.K. to adoption in the U.S. In particular, this study seeks to determine if the same factors are salient in both countries. Several studies have explored citizen acceptance of e-government services in the U.S. However, few studies have explored this phenomenon in the U.K. To identify the similarities and differences between the U.K. and the U.S. a survey is conducted in the U.K. and the findings are compared to the literature that investigates diffusion in the U.S. This study proposes a model of e-government adoption in the U.K. based on salient factors in the U.S. A survey is administered to 260 citizens in London to assess the importance of relative advantage, trust and the digital divide on intention to use e-government. The results of binary logistic regression indicate that there are cultural differences in e-government adoption in the U.K. and the U.S. The results indicate that of the prevailing adoption constructs, relative advantage and trust are pertinent in both the U.S. and the U.K., while ICT adoption barriers such as access and skill may vary by culture. Implications for research and practice are discussed
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