Static aeroelasticity of a composite oblique wing in transonic flows

One aircraft configuration that shows great promise in achieving high performance is that of an asymmetrically swept wing. When compared to conventional swept wings, these advantages include higher lift to drag ratios and reduced takeoff and landing speeds, which translate into greater performance in terms of fuel comsumption, loiter time, and range. However, the oblique wing has a number of disadvantages because of its asymmetric configuration. The question is how to best achieve maximum stability and roll equilibrium without compromising performance. Using aeroelastic tailoring to enhance aeroelastic stability and control has been demonstrated in several analyses, especially for the forward swept wing. The advantages and disadvantages for the oblique wing configuration are discussed

Segmented Switchers and Retailer Pricing Strategies

Empirical studies reveal a surprisingly wide variety of pricing strategies among retailers, even among Internet sellers of undifferentiated homogeneous goods, such as books and music CDs. Several empirical findings remain puzzling; for example, within the same market, some small retailers decide to discount deeply, whereas others forgo the price-sensitive switchers and price high. The authors present theoretical and empirical analyses that address these varied pricing strategies. A model of three asymmetric firms shows that under multiple switcher segments, in which different switchers compare prices at different retailers, firm-specific loyalty is not sufficient to explain the variety of pricing strategies. The authors demonstrate that a retailer's strategy to discount deeply or frequently is driven by the ratio of the size of switcher segments for which the retailer competes to its loyal segment size. The relative switcher-to-loyal ratios among retailers explain situations in which a small retailer finds it optimal to price high, despite having few loyals, or to discount and go for the switchers. The results of two empirical studies confirm the model's predictions for varied pricing strategies in the context of Internet booksellers. The analyses also present several implications. A small retailer can sometimes benefit from strategically limiting its access to switchers to soften price competition. A midsized retailer can benefit from targeting its switcher acquisition activities toward its larger rival, given the shallower discounts involved. When most switchers widely compare prices, a large retailer should offer few shallow discounts because other firms will more aggressively discount. The importance of switcher segmentation suggests that managers should carefully measure switching behavior in devising pricing strategies

Magnetization of Bi2_{2}Sr2_{2}CaCu2_{2}O8+δ_{8+\delta} micrometer thin ring and its depinning line

We demonstrate a geometrical effect on the depinning line (DL) of the flux line lattice of the Bi$_{2}$Sr$_{2}$CaCu$_{2}$O$_{8+\delta}$ high-T$_c$ superconductor (HTSC) micrometer ring. The DL shifts to notably lower temperatures in comparison to bulk crystals and thin flakes of the same sample. The shift is attributed to a decrease in the overall pinning potential due to a double size effect, namely: a) the ring thickness $\sim 1~\mu$m being smaller than the pinning correlation length, and b) the increase in the effective London penetration depth of the vortices (Pearl vortices). The large shift of the DL to lower temperatures may influence the suitability of this HTSC for applications in microstrip antennas and THz emitters.Comment: Reviewed, AAM. 13 pages, 10 figure

Pricing best sellers and traffic generators: the role of asymmetric cross-selling

Among the many items online retailers sell, some stand out as best sellers and are often sold at considerable discounts. Best seller discounting can encourage customer traffic and the purchase of a basket of other products in the same transaction. Although most studies treat retailers as symmetric, the cross-selling potential is generally asymmetric across retailers, since some online retailers have more products to sell. In addition, the cross-selling effect works both ways – customers intending to buy a best seller may buy other items in their shopping basket, while other customers intending to buy a basket may buy a best seller while visiting the retailer. The authors model the pricing implications of this rich variety of asymmetric cross-selling, with both best sellers and typical baskets acting as traffic generators and cross-sold products. The common wisdom that loss leader pricing leads to neither a significant increase in store traffic nor an increase in profits does not apply in an asymmetric case where one retailer has more products to cross-sell. The cross-selling potential of products even far down the best seller list is demonstrated. Empirical analyses provide support for key findings of the theoretical model using book pricing and sales rank data from multiple online retailers

Continuous vertical aerosol profiling with a multi-wavelength Raman polarization lidar over the Pearl River Delta, China

A dataset of particle optical properties of the highly polluted atmosphere over the Pearl River Delta (PRD), Guangzhou, China, is presented in this paper. The data were derived from the measurements of a multi-wavelength Raman and depolarization lidar PollyXT and a co-located AERONET sun photometer. The measurement campaign was conducted from November 2011 to mid-June 2012. These are the first Raman lidar measurements in the PRD that lasted for several months. A mean value of aerosol optical depth (AOD) of 0.54 ± 0.33 was observed by the sun photometer at 500 nm in the polluted atmosphere over this megacity for the whole measurement period. The lidar profiles frequently show lofted aerosol layers, which reach altitudes of up to 2 to 3 km and, especially during the spring season, up to 5 km. These layers contain between 12 and 56 % of the total AOD, with the highest values in spring. The aerosol types in these lofted layers are classified by their optical properties. The observed lidar ratio values range from 30 to 80 sr with a mean value of 48.0 ± 10.7 sr at 532 nm. The linear particle depolarization ratio at 532 nm lies mostly below 5 %, with a mean value of 3.6 ± 3.7 %. The majority of the Ångström exponents lie between 0.5 and 1.5, indicating a mixture of fine- and coarse-mode aerosols. These results reveal that mostly urban pollution particles mixed with particles produced from biomass and industrial burning are present in the atmosphere above the Pearl River Delta. Trajectory analyses show that these pollution mixtures arise mainly from local and regional sources

(3R,4S,5S,8S,10R,13R)-3-Hy­droxy­kaura-9(11),16-dien-18-oic acid

The title compound, C20H28O3, was isolated during our investigation into the chemical composition and pharmacological activity of Centipeda cunninghamii (DC.) A. Braun & Asch. (Asteraceae). The enanti­opure compound, a diterpene with a carbon skeleton, is composed of three six- and one five-membered rings in chair, twist-boat, half-chair and envelope conformations, respectively. Each mol­ecule makes one intra- and one inter­molecular O—H⋯O hydrogen bond in the crystal lattice, forming hydrogen-bonded chains along [010]. The absolute configuration of the compound was assigned on the basis of optical rotation measurements

Thiarubrine A, a bioactive constituent of Aspilia (Asteraceae) consumed by wild chimpanzees

Two African species of Aspilia (Asteraceae), which are used medicinally by man and which are eaten by wild chimpanzees in an unusual manner, were found to contain the potent antibiotic thiarubrine A as a major leaf phytochemical. Its presence in leaf material strengthens the view that the feeding behavior of wild chimpanzees is related to special physiological or pharmacological effects on the animals.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/42789/1/18_2005_Article_BF02004537.pd