Guidance of a low l/d vehicle entering the earth's atmosphere at speeds up to 50,000 feet per second

Guidance of low lift-drag ratio vehicle during earth atmosphere reentr

Conifer phytotoxicity and vegetation control efficacy of ten selected herbicides

Ten herbicides (atrazine, azafenidin, chlorsulfuron, clopyralid, hexazinone, imazapic, imazapyr, metsulfuron, pendimethalin, and sulfometuron) were evaluated for phytotoxicity in first-year seedlings of eight conifer species (Douglas-fir, grand fir, noble fir, redwood, Sitka spruce, western hemlock, western red cedar, and western white pine). Six of these herbicides (atrazine, clopyralid, hexazinone, imazapyr, metsulfuron, and sulfometuron) were also evaluated for vegetation control efficacy. Azafenedin, chiorsulfuron, imazapic, imazapyr, metsulfuron, pendimethalin, and sulfometuron were applied as fail site preparation treatments prior to spring conifer planting. Atrazine, clopyralid, hexazinone, and sulfometuron were applied as spring release treatments after conifer planting. All herbicides were applied at an operational rate (lx), as determined by label recommendations and industry standards, and a rate equal to three times the operational rate (3x). Treatments were replicated at three sites in western Oregon and Washington. Most of the herbicides tested in this study exhibited high levels of conifer safety. At the operational rate, hexazinone and sulfometuron were the only herbicides to cause significant injury to any of the conifer species tested. The hexazinone lx treatment caused mortality in western red cedar. The spring sulfometuron lx treatment caused mortality in grand fir and both sulfometuron lx treatments caused growth reductions in western red cedar. In addition, sulfometuron produced a subtle but non-significant trend of growth inhibition in five of the remaining six species, and appears to be a mild growth inhibitor in most conifers. Otherwise, none of the herbicides caused significant injury at the operational rate. Hexazinone and sulfometuron afforded the best overall weed control of the herbicides tested, Sulfometuron provided equal or better weed control as a fall site preparation treatment than as a spring release treatment. Atrazine provided the best combination of weed control efficacy and overall conifer safety. Clopyralid provided good control of weeds in the Asteraceae and Polygonaceae families, but was generally ineffective against other species. Metsulfuron and imazapyr were generally ineffective against the herbaceous species present in this study. Herbicide recommendations for various combinations of conifer crop and target weed species are provided in convenient reference tables. These tables facilitate the design of herbicide prescriptions for a variety of reforestation scenarios in the Pacific Northwest. Few of these herbicides are acutely toxic to any of the conifer species tested. We specify the conifer/herbicide combinations that should be avoided. Otherwise, foresters have a great deal of flexibility in developing vegetation management prescriptions with these chemicals

Signaling about norms: socialization under strategic uncertainty

We consider a signaling model where adults possess information about the dominant social norm. Children want to conform to whatever norm is dominant but, lacking accurate information, take the observed behavior of their parent as representative. We show that this causes a signaling distortion in adult behavior, even in the absence of conflicts of interest. Parents adopt attitudes that encourage their children to behave in a socially safe way, i.e. the way that would be optimal under maximum uncertainty about the prevailing social norm. We discuss applications to sexual attitudes, collective reputation, and trust

Purinergic Signaling Controls Spontaneous Activity in the Auditory System throughout Early Development

Spontaneous bursts of electrical activity in the developing auditory system arise within the cochlea before hearing onset and propagate through future sound-processing circuits of the brain to promote maturation of auditory neurons. Studies in isolated cochleae revealed that this intrinsically generated activity is initiated by ATP release from inner supporting cells (ISCs), resulting in activation of purinergic autoreceptors, K+ efflux, and subsequent depolarization of inner hair cells. However, it is unknown when this activity emerges or whether different mechanisms induce activity during distinct stages of development. Here we show that spontaneous electrical activity in mouse cochlea from both sexes emerges within ISCs during the late embryonic period, preceding the onset of spontaneous correlated activity in inner hair cells and spiral ganglion neurons, which begins at birth and follows a base to apex developmental gradient. At all developmental ages, pharmacological inhibition of P2Y1 purinergic receptors dramatically reduced spontaneous activity in these three cell types. Moreover, in vivo imaging within the inferior colliculus revealed that auditory neurons within future isofrequency zones exhibit coordinated neural activity at birth. The frequency of these discrete bursts increased progressively during the postnatal prehearing period yet remained dependent on P2RY1. Analysis of mice with disrupted cholinergic signaling in the cochlea indicate that this efferent input modulates, rather than initiates, spontaneous activity before hearing onset. Thus, the auditory system uses a consistent mechanism involving ATP release from ISCs and activation of P2RY1 autoreceptors to elicit coordinated excitation of neurons that will process similar frequencies of sound.Fil: Babola, Travis A.. University Johns Hopkins; Estados UnidosFil: Li, Sally. University Johns Hopkins; Estados UnidosFil: Wang, Zhirong. University Of Georgetown; Estados UnidosFil: Kersbergen, Calvin J.. University Johns Hopkins; Estados UnidosFil: Elgoyhen, Ana Belen. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Ingeniería Genética y Biología Molecular "Dr. Héctor N. Torres"; ArgentinaFil: Coate, Thomas M.. University Johns Hopkins; Estados UnidosFil: Bergles, Dwight E.. University Johns Hopkins; Estados Unido

Self-fulfilling regression and statistical discrimination

This paper provides a simple model which explains that statistical discrimination can arise in a purely self‐fulfilling manner. The story is as follows. (i) At the point of hiring, employers cannot observe workers’ productivities but can observe only their signals, such as test scores, and under perfect competition they pay for expected labor productivity conditional on signal observation, based on their belief about return to signal. (ii) Given the employers’ belief, workers choose an effort level, which affects the joint probability distribution over productivity–signal pairs. (iii) In equilibrium, the employers’ belief proves to be statistically consistent. We show that there may be multiple equilibria, and that equilibrium selection has nothing to do with economic fundamentals

Computing welfare losses from data under imperfect competition with heterogeneous goods

We study the percentage of welfare losses (PWL) yielded by imperfect competition under product differentiation. When demand is linear, if prices, outputs, costs and the number of firms can be observed, PWL is arbitrary in both Cournot and Bertrand equilibria. If in addition, the elasticity of demand (resp. cross elasticity of demand) is known, we can calculate PWL in Cournot (resp. Bertrand) equilibrium. When demand is isoelastic and there are many firms, PWL can be computed from prices, outputs, costs and the number of .rms. In all these cases we find that price-marginal cost margins and demand elasticities may influence PWL in a counterintuitive way. We also provide conditions under which PWL increases or decreases with concentration