How Much Pigment Should Flowers Have? Flowers With Moderate Pigmentation Have Highest Color Contrast

Floral pigments are a core component of flower colors, but how much pigment a flower should have to yield a strong visual signal to pollinators is unknown. Using an optical model and taking white, blue, yellow and red flowers as case studies, I investigate how the amount of pigment determines a flower’s color contrast. Modeled reflectance spectra are interpreted using established insect color vision models. Contrast as a function of the amount of pigment shows a pattern of diminishing return. Low pigment amounts yield pale colors, intermediate amounts yield high contrast, and extreme amounts of pigment do not further increase, and sometimes even decrease, a flower’s color contrast. An intermediate amount of floral pigment thus yields the highest visibility, a finding that is corroborated by previous behavioral experiments on bees. The implications for studies on plant-pollinator signaling, intraspecific flower color variation and the costs of flower color are discussed.

Optimal Endogenous Neural Noise Speeds Reaction Time

Objective: To determine whether the detection of weak visual stimuli is facilitated by a particular level of endogenous neural noise.Method: We measured the EEG while subjects responded to the occurrence of weak luminance increments. We used independent component (IC) analysis and dipole fitting to locate the neural sources of EEG responses to the stimuli in occipital, frontal, and temporal cortex. We then determined the relationship between the variability of the frequency-specific oscillations of the relevant neural sources in the 1 sec before stimulus presentation and the RT on hit (correct detection of the increment) trials.Results: An intermediate amount of power variability yielded the fastest RTs. This nonlinear relationship was found for occipital and frontal cortical sources and was strongest for theta (4- 8 Hz) and alpha (9-14 Hz) frequencies, but was also present for gamma (30-50 Hz) in frontal cortex.Conclusion: These results support the idea that an intermediate level of endogenous neural noise optimizes the brain’s response to a weak visual stimulus.

Characterization of Licorice Root Waste for Prospective Use as Filler in more Eco-Friendly Composite Materials

The extraction of glycyrrhizin from licorice root and stolon with ethanol/water solutions leaves a lignocellulosic residue, which could be potentially applied in biocomposites. This process proved difficult in principle, given the considerable hardness of this material as received, which impedes its use in polymer resins in large amounts. After ball milling, up to 10% of this fibrous residue, which shows very variable aspect ratio, was introduced into an epoxy matrix, to investigate its possible future application in sustainable polymers. Of the three composites investigated, containing 1, 5 and 10 wt% of licorice waste, respectively, by performing flexural testing, it was found that the introduction of an intermediate amount of filler proved the most suitable for possible development. Thermal characterization by thermogravimetry (TGA) did not indicate large variation of degradation properties due to the introduction of the filler. Despite the preliminary characteristics of this study, an acceptable resin-filler interface has been obtained for all filler contents. Issues to be solved in future study would be the possibility to include a larger amount of filler by better compatibilization and a more uniform distribution of the filler, considering their orientation, since most of it maintains an elongated geometry after ball milling.

Shape-Controlled Synthesis of Copper Indium Sulfide Nanostructures: Flowers, Platelets and Spheres

Colloidal semiconductor nanostructures have been widely investigated for several applications, which rely not only on their size but also on shape control. CuInS2 (often abbreviated as CIS) nanostructures have been considered as candidates for solar energy conversion. In this work, three-dimensional (3D) colloidal CIS nanoflowers and nanospheres and two-dimensional (2D) nanoplatelets were selectively synthesized by changing the amount of a sulfur precursor (tert-dodecanethiol) serving both as a sulfur source and as a co-ligand. Monodisperse CIS nanoflowers (~15 nm) were formed via the aggregation of smaller CIS nanoparticles when the amount of tert-dodecanethiol used in reaction was low enough, which changed towards the formation of larger (70 nm) CIS nanospheres when it significantly increased. Both of these structures crystallized in a chalcopyrite CIS phase. Using an intermediate amount of tert-dodecanethiol, 2D nanoplatelets were obtained, 90 nm in length, 25 nm in width and the thickness of a few nanometers along the a-axis of the wurtzite CIS phase. Based on a series of experiments which employed mixtures of tert-dodecanethiol and 1-dodecanethiol, a ligand-controlled mechanism is proposed to explain the manifold range of the resulting shapes and crystal phases of CIS nanostructures.

Disclosures Undisclosed

Category: Ethics Introduction/Purpose: The objective of our study was to analyze COI nondisclosure for US based research articles that were published to three prevalent orthopaedic journals from the beginning of 2014 to the end of 2016. Methods: All US-based research articles published to FAI, JBJS, and JOA from the beginning of 2014 to the end of 2016 were reviewed. COI disclosure sections were analyzed to determine if a disclosure was made for first and/or last authors. Authors disclosing any financial relationship involving employment, royalties/licensing, speaking, and consulting fees were recorded as having disclosed a potential COI. First and last authors were then searched for using CMS Open Payments search tool to determine if they had received any of the aforementioned payment types. To determine if a COI nondisclosure (disclosure discrepancy) was present, an author’s disclosure statement for a published article was compared to CMS Open Payments data from the year prior to publication of the article. We used CMS data from the year prior to a publication to account for the time it takes to construct a paper and have it published. Results: Across all journals and years, we obtained disclosure accuracy data for 3,465 total first and last authors publishing 1,770 research articles. Within this sample, 7.1% (245/3,465) of the authors had a recorded undisclosed conflict-of-interest and 13.2% (233/1,770) of articles had a first and/or last author with an undisclosed potential conflict-of-interest. When looking at each journal individually over the three-year period, FAI contained the highest percentage of authors with undisclosed COI’s (42.3%), JBJS contained the lowest percent of authors with an undisclosed COI (4.6%), and JOA had an intermediate amount of authors with an undisclosed COI (7.0%). Conclusion: Discrepancies between payment disclosures made by authors and those published in the CMS database were present in all three journals reviewed in this study. The percentage of articles containing an author with a disclosure discrepancy varies widely between these journals. However, when analyzing the percentage of disclosure discrepancies by year, no trend was found.

A Political Theory of Populism *

When voters fear that politicians may be influenced or corrupted by the rich elite, signals of integrity are valuable. As a consequence, an honest politician seeking reelection chooses “populist” policies—that is, policies to the left of the median voter—as a way of signaling that he is not beholden to the interests of the right. Politicians that are influenced by right-wing special interests respond by choosing moderate or even left-of-center policies. This populist bias of policy is greater when the value of remaining in office is higher for the politician; when there is greater polarization between the policy preferences of the median voter and right-wing special interests; when politicians are perceived as more likely to be corrupt; when there is an intermediate amount of noise in the information that voters receive; when politicians are more forward-looking; and when there is greater uncertainty about the type of the incumbent. We also show that soft term limits may exacerbate, rather than reduce, the populist bias of policies.

Impact of epistasis and pleiotropy on evolutionary adaptation

Evolutionary adaptation is often likened to climbing a hill or peak. While this process is simple for fitness landscapes where mutations are independent, the interaction between mutations (epistasis) as well as mutations at loci that affect more than one trait (pleiotropy) are crucial in complex and realistic fitness landscapes. We investigate the impact of epistasis and pleiotropy on adaptive evolution by studying the evolution of a population of asexual haploid organisms (haplotypes) in a model of N interacting loci, where each locus interacts with K other loci. We use a quantitative measure of the magnitude of epistatic interactions between substitutions, and find that it is an increasing function of K . When haplotypes adapt at high mutation rates, more epistatic pairs of substitutions are observed on the line of descent than expected. The highest fitness is attained in landscapes with an intermediate amount of ruggedness that balance the higher fitness potential of interacting genes with their concomitant decreased evolvability. Our findings imply that the synergism between loci that interact epistatically is crucial for evolving genetic modules with high fitness, while too much ruggedness stalls the adaptive process.

Patterns of tree diversity in response to logging in Algonquin Provincial Park

The acceleration of human disturbance on natural systems necessitates the understanding of the effects of disturbance on species diversity, in order to mitigate its impacts. The Intermediate Disturbance Hypothesis (IDH) provides a general framework for predicting how these effects will unfold, centered on the premise that diversity will be maximized at intermediate levels of disturbance, or after an intermediate amount of time has passed since the last disturbance. We investigated the impact of disturbance by logging in Algonquin Provincial Park, ON, Canada, on tree species diversity. We sampled 7 sites, with known times since the last logging event, ranging between 4 and 149 years. We found that species richness and diversity indeed peaked at an intermediate disturbance regime of approximately 80 years since logging. We also found that this maximum diversity was caused by a combination of early, pioneer, post-pioneer, sub-climax, and climax species. Our experiment shows that IDH is applicable to the mixed forests of Algonquin, and therefore, provided that sites are logged after a suitable amount of time has passed, it is possible to harvest trees and maintain diversity.

Computer-Assisted versus Teacher-Directed Teaching of Community Living Skills in People with a Mild Learning Disability

An experiment was carried out in which adults with a learning disability of the mild type undertook either computer-assisted or teacher-implemented instruction in community living skills, with a third group acting as a control group. All groups were pre-tested on a standardised psychometric measure of community living skills (the HANC 2 subscale of the Hampshire Assessment for Living with Others test), after which the experimental groups received one half-day per week training in such skills as money handling and budgeting for 3 months, when all groups were reassessed. It was found that both the teacher-led and computer-assisted instruction groups appeared to gain more than the control group, but only the teacher-led group differed significantly from the control group. The computer-assisted group improved in their scores by an intermediate amount, with their gains being non-significantly different from either the control or the teacher-led groups. The strengths and weaknesses of the software used in the study are discussed.