The evolution of signal design in manakin plumage ornaments

Animal signals are characterized by two design components: efficacy (detectability) and content (message being conveyed). Selection for efficient signal perception should favor the evolution of traits that exhibit an optimal balance between these two design components. We examined the evolution of signal design in the colorful plumage ornaments of manakins (Aves: Pipridae). We used a model of avian color space to quantify how differences in plumage coloration would be perceived by a typical passerine bird and examined patterns of coloration across 50 species of manakin. Using phylogenetically independent contrasts, we show that plumage contrast against the background increases with sexual dichromatism in males but not females, suggesting that sexual selection has favored the evolution of male plumage ornaments that enhance signal efficacy. Plumage contrast within individuals also increased with dichromatism in males but not females. Finally, plumage colors produced by different mechanisms, which may reveal different aspects of quality, resulted in different degrees of contrast against the background. Our findings suggest that selection for signal efficacy and content may sometimes be opposing, creating a trade-off between these two components of signal design. Manakins may mediate this trade-off by combining multiple plumage ornaments that differ in efficacy and content. © 2007 by The University of Chicago

Estudio Taxonómico de Poblaciones de Peltamigratus longistylus. Doucet,1980 y P. perscitus Doucet, 1980 (NEMATODA: TYLENCHIDA)

Se detallan los caracteres morfométricos de dos poblaciones de Peltramigratus longistylus Doucet, 1980 y de una población de P. perscitus Doucet, 1980, así como los caracteres morfológicos más importantes de la poblaciones mencionadas

El cultivar de tomate superman y una población del nematodo nacobbus aberrans

Fil: Cabrera, V. Universidad Nacional de Córdoba. Instituto Multidiciplinario de Biología Vegetal; Argentina.Fil: Dottori, N. Universidad Nacional de Córdoba. Instituto Multidiciplinario de Biología Vegetal; Argentina.Fil: Doucet, M. E. Universidad Nacional de Córdoba. CZA. Laboratorio de Nematología; Argentina.El tomate es una hortaliza de gran importancia en numerosos países; su cultivo ha adquirido relevancia económica en todo el mundo. Sin embargo, la productividad está severamente limitada por plagas y enfermedadesFil: Cabrera, V. Universidad Nacional de Córdoba. Instituto Multidiciplinario de Biología Vegetal; Argentina.Fil: Dottori, N. Universidad Nacional de Córdoba. Instituto Multidiciplinario de Biología Vegetal; Argentina.Fil: Doucet, M. E. Universidad Nacional de Córdoba. CZA. Laboratorio de Nematología; Argentina.Ciencias de las Plantas, Botánic

El cultivar de tomate mykonos y su relación con una población del neamatodo nacobbus aberrans

Fil: Cabrera, V. Universidad Nacional de Córdoba. Instituto Multidiciplinario de Biología Vegetal; ArgentinaFil: Dottori, N. Universidad Nacional de Córdoba. Instituto Multidiciplinario de Biología Vegetal; Argentina.Fil: Doucet, M. E. Universidad Nacional de Córdoba. CZA. Laboratorio de Nematología; Argentina.El tomate es la hortaliza más cultivada mundialmente y de mayor valor económico. Su productividad está limitada por plagas, destacándose el nematodo fitoparásito Nacobbus aberrans. El cultivar Mykonos se comercializa como resistente a nematodos, sin precisar la identidad específica del parásito.Fil: Cabrera, V. Universidad Nacional de Córdoba. Instituto Multidiciplinario de Biología Vegetal; ArgentinaFil: Dottori, N. Universidad Nacional de Córdoba. Instituto Multidiciplinario de Biología Vegetal; Argentina.Fil: Doucet, M. E. Universidad Nacional de Córdoba. CZA. Laboratorio de Nematología; Argentina.Ciencias de las Plantas, Botánic

Comparison of CO2 capture by ex-situ accelerated carbonation and in in-situ naturally weathered coal fly ash

Natural weathering at coal power plants ash dams occurs via processes such as carbonation, dissolution, co-precipitation and fluid transport mechanisms which are responsible for the long-term chemical, physical and geochemical changes in the ash. Very little information is available on the natural carbon capture potential of wet or dry ash dams. This study investigated the extent of carbon capture in a wet-dumped ash dam and the mineralogical changes promoting CO2 capture, comparing this natural phenomenon with accelerated ex-situ mineral carbonation of fresh fly ash (FA). Significant levels of trace elements of Sr, Ba and Zr were present in both fresh and weathered ash. However Nb, Y, Sr, Th and Ba were found to be enriched in weathered ash compared to fresh ash. Mineralogically, fresh ash is made up of quartz, mullite, hematite, magnetite and lime while weathered and carbonated ashes contained additional phases such as calcite and aragonite. Up to 6.5 wt % CO2 was captured by the fresh FA with a 60% conversion of calcium to CaCO3 via accelerated carbonation (carried out at 2 h, 4Mpa, 90 o C, bulk ash and a S/L ratio of 1). On the other hand 6.8 wt % CO2 was found to have been captured by natural carbonation over a period of 20 years of wet disposed ash. Thus natural carbonation in the ash dumps is significant and may be effective in capturing CO2.Web of Scienc

The structure of the protoplanetary disk surrounding three young intermediate mass stars. II. Spatially resolved dust and gas distribution

[Abridged] We present the first direct comparison of the distribution of the gas, as traced by the [OI] 6300 AA emission, and the dust, as traced by the 10 micron emission, in the protoplanetary disk around three intermediate-mass stars: HD 101412, HD 135344 B and HD 179218. N-band visibilities were obtained with VLTI/MIDI. Simple geometrical models are used to compare the dust emission to high-resolution optical spectra in the 6300 AA [OI] line of the same targets. The disks around HD 101412 and HD 135344 B appear strongly flared in the gas, but self-shadowed in the dust beyond ~ 2 AU. In both systems, the 10 micron emission is rather compact (< 2 AU) while the [OI] brightness profile shows a double peaked structure. The inner peak is strongest and is consistent with the location of the dust, the outer peak is fainter and is located at 5-10 AU. Spatially extended PAH emission is found in both disks. The disk around HD 179218 is flared in the dust. The 10 micron emission emerges from a double ring-like structure with the first ring peaking at ~ 1 AU and the second at ~ 20 AU. No dust emission is detected between ~ 3 -- 15 AU. The oxygen emission seems also to come from a flared structure, however, the bulk of this emission is produced between ~ 1 -- 10 AU. This could indicate a lack of gas in the outer disk or could be due to chemical effects which reduce the abundance of OH -- the parent molecule of the observed [OI] emission -- further away from the star. The three systems, HD 179218, HD 135344 B and HD 101412, may form an evolutionary sequence: the disk initially flared becomes flat under the combined action of gas-dust decoupling, grain growth and dust settling.Comment: Accepted for publication in A&

Neuromuscular Electrical Stimulation Effects on Skeletal Muscle Fatigue in Older Adults

Neuromuscular electrical stimulation (NMES) is often used as a rehabilitative modality and evidence has suggested that high frequencies of NMES may elicit increases in muscle strength. However, little is known regarding the effects of a high-frequency NMES intervention on voluntary skeletal muscle fatigue. PURPOSE: The aim of this study was to determine the effect of a 4-week high-frequency NMES intervention on voluntary muscular fatigue and changes in neuromuscular activation patterns of the quadriceps during voluntary fatiguing muscle contractions in older adults. METHODS: Seventeen healthy, older adults (68.8 ± 1.8 years old) participated in the study (NMES: n = 12; SHAM: n = 5). Each participant was seated on an isokinetic dynamometer, and a 40-min NMES treatment was applied to the quadriceps muscles of each leg 3x/week for 4 weeks with the stimulation frequency set at 60 Hz. Stimulation intensity was set to achieve 15% of knee extension maximal voluntary contraction (MVC). Those in the SHAM group underwent the same treatment procedures but did not receive the NMES treatment. All subjects performed maximal voluntary contractions (MVC) and an intermittent knee extension isometric submaximal voluntary fatigue task at 50% MVC until the fatigue criteria were met for pre-post testing. Surface electromyography (sEMG) of the vastus lateralis (VL) and vastus medialis (VM) muscles were recorded during the fatigue task to examine changes in muscle activation. EMG data were quantified for root mean square (RMS) EMG and reported as a percent rate of change over the duration of the fatigue task and median frequency (MF) is reported as the average MF during the fatigue task. Repeated measures ANOVAs were used to determine differences pre-post NMES for muscular endurance time, MVC and EMG measures. Statistical significance was set at p \u3c 0.05. RESULTS: MVC increased pre-post NMES in the NMES group (117.1 ± 8.7 Nm vs 127.6 ± 11.1 Nm, p = 0.049; pre- and post-training, respectively) with no change in SHAM (p = 0.96). Muscular endurance time did not change pre-post NMES (NMES: 159.3 ± 20.1s vs 141.9 ± 21.2s, p = 0.29; SHAM: 242.2 ± 43.3s vs 202.9 ± 23.3s, p = 0.13; pre- and post-training, respectively). RMS EMG rate of change did not change following NMES treatment (NMES: VL: 16.6 ± 3.6% vs 18.8 ± 10.4%, p = 0.84; VM: 11.4 ± 2.1% vs 19.6 ± 5.5%, p = 0.15; SHAM: VL: 7.8 ± 1.6% vs 7.1 ± 3.0%, p = 0.81; VM: 7.1 ± 3.3% vs 5.9 ± 2.2%, p = 0.55; pre- and post-training, respectively). Also, there was no difference in MF EMG with NMES training (NMES: VL: 77.6 ± 4.1 Hz vs 74.9 ± 3.6 Hz, p = 0.13; VM: 72.5 ± 2.4 Hz vs 72.6 ± 2.2 Hz, p = 0.97; SHAM: VL: 79.3 ± 3.4 Hz vs 80.2 ± 4.9 Hz, p = 0.85; VM: 76.9 ± 3.7 Hz vs 83.9 ± 5.1 Hz, p = 0.12; pre- and post-training, respectively). CONCLUSION: Treatment with high-frequency NMES did not improve muscle endurance or related EMG parameters. It is possible that NMES induced adaptations may be frequency-specific and that high-frequency NMES may not be efficacious when the goal is to improve skeletal muscle endurance

Robust Online Hamiltonian Learning

In this work we combine two distinct machine learning methodologies, sequential Monte Carlo and Bayesian experimental design, and apply them to the problem of inferring the dynamical parameters of a quantum system. We design the algorithm with practicality in mind by including parameters that control trade-offs between the requirements on computational and experimental resources. The algorithm can be implemented online (during experimental data collection), avoiding the need for storage and post-processing. Most importantly, our algorithm is capable of learning Hamiltonian parameters even when the parameters change from experiment-to-experiment, and also when additional noise processes are present and unknown. The algorithm also numerically estimates the Cramer-Rao lower bound, certifying its own performance.Comment: 24 pages, 12 figures; to appear in New Journal of Physic

EphA4 signaling regulates phospholipase Cgamma1 activation, cofilin membrane association, and dendritic spine morphology

Specialized postsynaptic structures known as dendritic spines are the primary sites of glutamatergic innervation at synapses of the CNS. Previous studies have shown that spines rapidly remodel their actin cytoskeleton to modify their shape and this has been associated with changes in synaptic physiology. However, the receptors and signaling intermediates that restructure the actin network in spines are only beginning to be identified. We reported previously that the EphA4 receptor tyrosine kinase regulates spine morphology. However, the signaling pathways downstream of EphA4 that induce spine retraction on ephrin ligand binding remain poorly understood. Here, we demonstrate that ephrin stimulation of EphA4 leads to the recruitment and activation of phospholipase Cgamma1 (PLCgamma1) in heterologous cells and in hippocampal slices. This interaction occurs through an Src homology 2 domain of PLCgamma1 and requires the EphA4 juxtamembrane tyrosines. In the brain, PLCgamma1 is found in multiple compartments of synaptosomes and is readily found in postsynaptic density fractions. Consistent with this, PLC activity is required for the maintenance of spine morphology and ephrin-induced spine retraction. Remarkably, EphA4 and PLC activity modulate the association of the actin depolymerizing/severing factor cofilin with the plasma membrane. Because cofilin has been implicated previously in the structural plasticity of spines, this signaling may enable cofilin to depolymerize actin filaments and restructure spines at sites of ephrin-EphA4 contact