Improving tall fescue shade tolerance : identifying candidate genotypes

Paper presented at the 11th North American Agroforesty Conference, which was held May 31-June 3, 2009 in Columbia, Missouri.In Gold, M.A. and M.M. Hall, eds. Agroforestry Comes of Age: Putting Science into Practice. Proceedings, 11th North American Agroforestry Conference, Columbia, Mo., May 31-June 3, 2009.Tall fescue (Schedonorus arundinaceus) is genetically variable for many agronomic traits, so it might be possible to increase its persistence and productivity in shaded agroforestry applications. The objective of this research was to identify high yielding, shade-tolerant genotypes. Seed was obtained from eight families: seven plant introductions of European origin: 234718, 234720, 234882, 234884, 235018, 235019, 235036, and one cultivar (Kentucky 31). Two sequential experiments were conducted to select genotypes for dry mass yield during April to September. Experiment (Exp) 1 included 30 genotypes of each of the eight families randomly assigned to each of two microenvironments: artificially shaded with fabric and unshaded. Maximum and minimum yields were 93.9 and 47.1 g family-1 for Kentucky 31 and 235036, respectively. After 1 yr, the proportion of vigorous survivors in Exp 1 was greater in the unshaded than shaded environment (0.40 and 0.09, respectively), and ranged from 0 to 0.56 (235036 and Kentucky 31, respectively). Forty robust genotypes (one later died) from four families (234718, 234720, 235019, and Kentucky 31) were selected from shaded and unshaded microenvironments of Exp 1, clonally propagated, and evaluated in pots for 2 yr in Exp 2. Shade-selected Kentucky 31 yielded more (31.0 g plant-1) in shade than other shade-selected families (25.2 to 25.8 g plant-1). Eleven genotypes in the top quartile (yield [greater than] 33.0 g plant-1) were selected for further testing. All genotypes were endophyte (Neotyphodium coenophialum)-infected. Future research will include seed increases and measuring yield in shaded, water-deficit conditions of a tree understory.David M. Burner (1) and Chuck P. West (2) ; 1. USDA-ARS, Dale Bumpers Small Farms Research Center, 6883 South State Hwy. 23, Booneville, AR 72927. 2. University of Arkansas, 1366 W. Altheimer Drive, Fayetteville, AR 72704.Includes bibliographical references

Buried Ion-Exchanged Glass Wavelengths: Burial-Depth Dependence on Waveguide Width

A detailed theoretical and experimental study of the depth dependence of buried ion-exchanged waveguides on waveguide width is reported. Modeling, which includes the effect of nonhomogeneous time-dependent electric field distribution, agrees well with our experiments showing that burial depth increases linearly with waveguide width. These results may be used in the proper design of integrated optical circuits that need waveguides of different widths at different sections, such as arrayed waveguide gratings

The ACS Fornax Cluster Survey. II. The Central Brightness Profiles of Early-Type Galaxies: A Characteristic Radius on Nuclear Scales and the Transition from Central Luminosity Deficit to Excess

We analyse HST surface brightness profiles for 143 early-type galaxies in the Virgo and Fornax Clusters. Sersic models provide accurate descriptions of the global profiles with a notable exception: the observed profiles deviate systematically inside a characteristic "break" radius of R_b ~ 0.02R_e where R_e is the effective radius of the galaxy. The sense of the deviation is such that bright galaxies (M_B < -20) typically show central light deficits with respect to the inward extrapolation of the Sersic model, while the great majority of low- and intermediate-luminosity galaxies (-19.5 < M_B < -15) show central light excesses; galaxies occupying a narrow range of intermediate luminosities (-20 < M_B < -19.5) are usually well fitted by Sersic models over all radii. The slopes of the central surface brightness profiles, when measured at fixed fractions of R_e, vary smoothly as a function of galaxy luminosity in a manner that depends sensitively on the choice of measurement radius. We show that a recent claim of strong bimodality in slope is likely an artifact of the galaxy selection function used in that study. To provide a more robust characterization of the inner regions of galaxies, we introduce a parameter that describes the central luminosity deficit or excess relative to the inward extrapolation of the outer Sersic model. We find that this parameter varies smoothly over the range of ~ 720 in blue luminosity spanned by the Virgo and Fornax sample galaxies, with no evidence for a dichotomy. We argue that the central light excesses (nuclei) in M_B > -19 galaxies may be the analogs of the dense central cores that are predicted by some numerical simulations to form via gas inflows. (ABRIDGED)Comment: To appear in the Astrophysical Journal, December 2007. Full resolution paper available at http://www.cfa.harvard.edu/~ajordan/ACSFCS/Home.htm

Reliability of a 2-Bout exercise test on a Wattbike cycle ergometer

Purpose: To determine the intraday and interday reliability of a 2 × 4-min performance test on a cycle ergometer (Wattbike) separated by 30 min of passive recovery (2 × 4MMP). Methods: Twelve highly trained cyclists (mean ± SD; age = 20 ± 2 y, predicted VO2max = 59.0 ± 3.6 mL · kg–1 · min–1) completed six 2 × 4MMP cycling tests on a Wattbike ergometer separated by 7 d. Mean power was measured to determine intraday (test 1 [T1] to test 2 [T2]) and interday reliability (weeks 1–6) over the repeated trials. Results: The mean intraday reliabilities of the 2 × 4MMP test, as expressed by the typical error of measurement (TEM, W) and coefficient of variation (CV, %) over the 6 wk, were 10.0 W (95% confidence limits [CL] 8.2–11.8), and 2.6% (95%CL 2.1–3.1), respectively. The mean interday reliability TEM and CV for T1 over the 6 wk were 10.4 W (95%CL 8.7–13.3) and 2.7% (95%CL 2.3–3.5), respectively, and 11.7 W (95%CL 9.8–15.1) and 3.0% (95%CL 2.5–3.9) for T2. Conclusion: The testing protocol performed on a Wattbike cycle ergometer in the current study is reproducible in highly trained cyclists. The high intraday and interday reliability make it a reliable method for monitoring cycling performance and for investigating factors that affect performance in cycling events

The presumption of sociality: Social learning in diverse contexts in brown-headed cowbirds (Molothrus ater).

Data are presented on social and vocal learning in cowbirds (Molothrus ater) housed in large aviaries and given more degrees of freedom than in conventional experimental studies. The studies show that social and vocal outcomes are facultative responses to social contexts. Several findings are reviewed: First, cowbirds quickly self-organize into groups by age and sex; second, opportunities to interact across age and sex do exist and affect courtship competence; third, female cowbirds organize themselves differently in the presence and absence of male competition; and fourth, young, naive cowbirds show rapid and differential sensitivity to group dynamics. Taken as a whole, the data show that social Umwelten are dynamic, developmental ecologies. Solitude is a human presumption. Every quiet step is thunder to beetle life underfoot, a tug of impalpable thread on the web pulling the mate to mate and predator to prey, a beginning or an end. Every choice is a new beginning for the chosen.-Barbara Kingsolver, Prodigal Summer Terra firma provides humans with sure footing but sometimes narrow thinking about the sensory world of other inhabitants. The air-ground complex is one of myriad environments, many neithe

The Christmas Cove Dyke of coastal Maine, USA, and regional sources for Early Mesozoic flood basalts in northeastern North America

 A large Early Mesozoic quartz tholeiite dyke has been mapped discontinuously for 190 km in southern coastal Maine, USA. Including its type locality at Christmas Cove (South Bristol, Maine, USA), the dyke has features of a generally ENE strike; dip usually steep to the SSE but abruptly turning very shallow in short sections; and widths of 9 to 35 m. The dyke rock has a distinctive cross-columnar field appearance, and a subophitic to micro-porphyritic texture with abundant Ti-bearing augite, calcic plagioclase, scattered euhedral orthopyroxene phenocrysts, and coarse-grained glomerophyric clumps of augite with plagioclase. Several 40Ar/39Ar whole-rock dates for this and associated regional dykes are close to 201 Ma, in agreement with ages of other Early Mesozoic dykes and basalts of the Central Atlantic Magmatic Province (CAMP). The geographic position, age, whole-rock chemistry, and petrography indicate that the Christmas Cove Dyke is co-magmatic or contiguous with the Higganum-Holden Dyke of southern New England, which was a source for the Talcott Basalt of the Early Mesozoic Hartford rift basin. The dyke system is a 700-km long fissure source for the earliest rift basin basalts preserved in northeastern North America, and it virtually connects the Hartford Basin and the Fundy Basin in Atlantic Canada. The Caraquet Dyke of New Brunswick and central Maine may be co-magmatic with the Buttress Dyke and Holyoke Basalt of southern New England, but lava from it is not preserved in Atlantic Canada or Maine.

Improved timber harvest techniques maintain biodiversity in tropical forests

Tropical forests are selectively logged at 20 times the rate at which they are cleared, and at least a fifth have already been disturbed in this way. In a recent pan-tropical assessment, Burivalova et al. demonstrate the importance of logging intensity as a driver of biodiversity decline in timber estates. Their analyses reveal that species richness of some taxa could decline by 50% at harvest intensities of 38 m3 ha-1. However, they did not consider the extraction techniques that lead to these intensities. Here, we conduct a complementary meta-analysis of assemblage responses to differing logging practices: conventional logging and reduced-impact logging. We show that biodiversity impacts are markedly less severe in forests that utilise reduced-impact logging, compared to those using conventional methods. While supporting the initial findings of Burivalova et al., we go on to demonstrate that best practice forestry techniques curtail the effects of timber extraction regardless of intensity. Therefore, harvest intensities are not always indicative of actual disturbance levels resulting from logging. Accordingly, forest managers and conservationists should advocate practices that offer reduced collateral damage through best practice extraction methods, such as those used in reduced-impact logging. Large-scale implementation of this approach would lead to improved conservation values in the 4 million km2 of tropical forests that are earmarked for timber extraction

Depositional constraints from detrital zircon geochronology of strata from multiple lithotectonic belts in south-central Maine, USA

The bedrock geology of south-central Maine is characterized by a series of fault-bounded lithotectonic terranes that were accreted onto the Laurentian margin during Silurian-Devonian orogenesis.  The multiple phases of deformation and metamorphism associated with this tectonism obscured most primary features in the protolith rocks, leading to uncertainties in their pre-accretionary history. Here we present the results of detrital zircon geochronology from five of these terranes and make interpretations on their depositional ages, sediment provenance, and tectonic setting of deposition.Detrital zircon from Silurian rocks of the Vassalboro Group in the eastern-most portion of the Central Maine basin indicate sediment input in an extensional setting from both Laurentian and Ordovician sources.  Results from Ordovician rocks of the Casco Bay Group of the Liberty-Orrington belt support earlier findings that these rocks have strong peri-Gondwanan affinities.  Detrital zircon from the Appleton Ridge Formation and Ghent phyllite of the Fredericton trough are consistent with a peri-Gondwanan sediment source with no evidence of Laurentian sediment input.  These findings are consistent with that of Dokken et al. (2018) for older Fredericton trough strata (i.e., Digdeguash Formation) east of the Fredericton fault in southern New Brunswick.  Two samples from the Jam Brook complex reveal extreme differences in depositional age (Ordovician vs. Mesoproterozoic) and tectonic affinity and support the hypothesis that this narrow belt represents a fault complex containing a wide variety of stratigraphic units.  Detrital zircon from Ordovician rocks of the Benner Hill Sequence indicate a peri-Gondwanan sediment source with no Laurentian input.Collectively, the pre-Silurian rocks of the Liberty-Orrington belt, Jam Brook complex, Benner Hill Sequence, and Late Ordovician-Early Silurian strata from the Appleton Ridge and Ghent phyllite in the Fredericton trough show peri-Gondwanan affinities with no evidence of Laurentian sediment input.  This suggests a barrier exisited between the Laurentian margin and these peri-Gondwanan terranes prior to about 435 Ma.  In contrast, Silurian strata from the eastern portion of the Central Maine basin do show evidence of a Laurentian sediment source, along with deposition in an extensional setting (lacking in all other samples), thus signaling a fundamental change in tectonic regime

Alpha‐melanocyte stimulating hormone increases the activity of melanocortin‐3 receptor‐expressing neurons in the ventral tegmental area

The mesocorticolimbic dopamine system, the brain’s reward system, regulates multiple behaviours, including food intake and food reward. There is substantial evidence that the melanocortin system of the hypothalamus, an important neural circuit controlling feeding and body weight, interacts with the mesocorticolimbic dopamine system to affect feeding, food reward and body weight. For example, melanocortin‐3 receptors (MC3Rs) are expressed in the ventral tegmental area (VTA) and our laboratory previously showed that intra‐VTA injection of the MC3R agonist, MTII, decreases home‐cage food intake and operant responding for sucrose pellets. However, the cellular mechanisms underlying the effects of intra‐VTA alpha‐melanocyte stimulating hormone (α‐MSH) on feeding and food reward are unknown. To determine how α‐MSH acts in the VTA to affect feeding, we performed electrophysiological recordings in acute brain slices from mice expressing enhanced yellow fluorescent protein in MC3R neurons to test how α‐MSH affects the activity of VTA MC3R neurons. α‐MSH significantly increased the firing rate of VTA MC3R neurons without altering the activity of non‐MC3R expressing VTA neurons. In addition, the α‐MSH‐induced increase in MC3R neuron activity was independent of fast synaptic transmission and intracellular Ca2+ levels. Finally, we show that the effect of α‐MSH on MC3R neuron firing rate is probably activity‐dependent. Overall, these studies provide an important advancement in the understanding of how α‐MSH acts in the VTA to affect feeding and food reward.Key pointsAlpha‐melanocyte stimulating hormone (α‐MSH) is an anorexigenic peptide. Injection of the α‐MSH analog MTII into the ventral tegmental area (VTA) decreases food and sucrose intake and food reward.Melanocortin‐3 receptors (MC3R) are highly expressed in the VTA, suggesting that the effects of intra‐VTA α‐MSH may be mediated by α‐MSH changing the activity of MC3R‐expressing VTA neurons.α‐MSH increased the firing rate of MC3R VTA neurons in acute brain slices from mice, although it did not affect the firing rate of non‐MC3R VTA neurons.The α‐MSH induced increase in MC3R neuron firing rate is probably activity‐dependent, and was independent of fast synaptic transmission and intracellular Ca2+ levels.These results help us to better understand how α‐MSH acts in the VTA to affect feeding and other dopamine‐dependent behaviours.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/149572/1/tjp13547.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/149572/2/tjp13547_am.pd