Price competition and store competition: Store brands vs. national brand

This paper studies pricing strategies in a market channel composed of one national brand manufacturer and two retailers who, each, carry their own store brand and a national brand products. The model accounts for product competition between store brands and the national brand products, as well as for store competition between retailers.     

Near-complete suppression of quantum dot blinking in ambient conditions

Colloidal semiconductor quantum dots are attractive fluorophores for multicolor imaging because of broad absorption and narrow emission spectra, and they are brighter and far more photostable than organic dyes. However, severe intermittence in emission (also known as blinking) has been universally observed from single dots and has been considered an intrinsic limitation difficult to overcome. This is unfortunate because growing applications in spectroscopy of single biological molecules and quantum information processing using single photon sources could greatly benefit from long-lasting and nonblinking single-molecule emitters. For instance, in a recent application of single-dot imaging, the tracking of membrane receptors was interrupted frequently due to the stroboscopic nature of recording. Blinking can also reduce the brightness in ensemble imaging via signal saturation. Here we show that the quantum dot blinking can be suppressed with the emission duty cycle approaching 100% while maintaining biocompatibility.     

Stiffness quantification of conductive polymers for bioelectrodes

Conductive polymer (CP) coatings can improve the performance of metallic bioelectrodes in implantable devices, a benefit which is partially attributed to the “softer” material interface. However, due to the nature of CP fabrication on metallic substrates, accurate quantification of mechanical properties has been difficult to achieve. This study demonstrates that peak‐force quantitative nanomechanical mapping (PF‐QNM) is a robust technique for determining the modulus of CP coatings. The effect of dopant size, chemistry, and film hydration on the mechanical properties of poly(3,4‐ethylene dioxythiophene) (PEDOT) is also examined. Analysis of PEDOT doped with poly(styrene sulfonate) produced across five different thicknesses confirms the utility of PF‐QNM in yielding quantitative, repeatable moduli in both the dry and hydrated state. By doping PEDOT with paratoluene sulfonate and perchlorate (ClO₄) it is shown that the hydrophilicity and the size of the dopant are both critical factors influencing CP mechanical properties in the hydrated environment. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014 , 52, 666–675     

Single-molecule quantum-dot fluorescence resonance energy transfer.

Colloidal semiconductor quantum dots are promising for single-molecule biological imaging due to their outstanding brightness and photostability. As a proof of concept for single-molecule fluorescence resonance energy transfer (FRET) applications, we measured FRET between a single quantum dot and a single organic fluorophore Cy5. DNA Holliday junction dynamics measured with the quantum dot/Cy5 pair are identical to those obtained with the conventional Cy3/Cy5 pair, that is, conformational changes of individual molecules can be observed by using the quantum dot as the donor.     

The Invariance Principle for the Total Length of the Nearest-Neighbor Graph

Let be the Poisson point process with intensity 1 in R^d and let be . We obtain a strong invariance principle for the total length of the nearest-neighbor graph on .     

Isomeric yield ratios for the natNd(γ, xn) 139m,g; 141m,gNd reactions in the bremsstrahlung energy region from 45 to 60 MeV

The independent isomeric yield ratios (IR) for the ^139m,gNd and the ^141m,gNd isomeric pairs produced from the ^natNd(γ, xn) reactions were determined by the activation and the off-line γ-ray spectrometric technique at the end-point bremsstrahlung energies of 45, 50, 55, and 60 MeV in the 100 MeV electron Linac of the Pohang accelerator laboratory, Korea. The present IR for the ^141m,gNd isomeric pair were compared with those from the literature measured by the bremsstrahlung and the neutron to examine the role of excitation energy. The obtained IR for the ^139m,gNd and the ^141m,gNd isomeric pairs from ^natNd(γ, xn) reactions were compared with those from the ¹⁴¹Pr(p, x), the ^natCe(³He, x), and the ¹³⁶Ce(α, n) reactions to examine the role of parameters in entrance channel i.e. excitation energy and the effect of the input angular momentum. The present IR of ^139m,gNd and ^141m,gNd were compared with those calculated by using the TALYS 1.4 code as well as those from the literature data of above mentioned reactions.     

Intrinsic Z-DNA is stabilized by the conformational selection mechanism of Z-DNA-binding proteins

Z-DNA, a left-handed isoform of Watson and Crick’s B-DNA, is rarely formed without the help of high salt concentrations or negative supercoiling. However, Z-DNA-binding proteins can efficiently convert specific sequences of the B conformation into the Z conformation in relaxed DNA under physiological salt conditions. As in the case of many other specific interactions coupled with structural rearrangements in biology, it has been an intriguing question whether the proteins actively induce Z-DNAs or passively trap transiently preformed Z-DNAs. In this study, we used single-molecule fluorescence assays to observe intrinsic B-to-Z transitions, protein association/dissociation events, and accompanying B-to-Z transitions. The results reveal that intrinsic Z-DNAs are dynamically formed and effectively stabilized by Z-DNA-binding proteins through efficient trapping of the Z conformation rather than being actively induced by them. Our study provides, for the first time, detailed pictures of the intrinsic B-to-Z transition dynamics and protein-induced B-to-Z conversion mechanism at the single-molecule level.     

Conductive Hydrogels: Mechanically Robust Hybrids for Use as Biomaterials

A hybrid system for producing conducting polymers within a doping hydrogel mesh is presented. These conductive hydrogels demonstrate comparable electroactivity to conventional conducting polymers without requiring the need for mobile doping ions which are typically used in literature. These hybrids have superior mechanical stability and a modulus significantly closer to neural tissue than materials which are commonly used for medical electrodes. Additionally they are shown to support the attachment and differentiation of neural like cells, with improved interaction when compared to homogeneous hydrogels. The system provides flexibility such that biologic incorporation can be tailored for application.