Slow-light enhanced optical detection in liquid-infiltrated photonic crystals

Slow-light enhanced optical detection in liquid-infiltrated photonic crystals is theoretically studied. Using a scattering-matrix approach and the Wigner-Smith delay time concept, we show that optical absorbance benefits both from slow-light phenomena as well as a high filling factor of the energy residing in the liquid. Utilizing strongly dispersive photonic crystal structures, we numerically demonstrate how liquid-infiltrated photonic crystals facilitate enhanced light-matter interactions, by potentially up to an order of magnitude. The proposed concept provides strong opportunities for improving existing miniaturized absorbance cells for optical detection in lab-on-a-chip systems.Comment: Paper accepted for the "Special Issue OWTNM 2007" edited by A. Lavrinenko and P. J. Robert

Electro-hydrodynamics of binary electrolytes driven by modulated surface potentials

We study the electro-hydrodynamics of the Debye screening layer that arises in an aqueous binary solution near a planar insulating wall when applying a spatially modulated AC-voltage. Combining this with first order perturbation theory we establish the governing equations for the full non-equilibrium problem and obtain analytic solutions in the bulk for the pressure and velocity fields of the electrolyte and for the electric potential. We find good agreement between the numerics of the full problem and the analytics of the linear theory. Our work provides the theoretical foundations of circuit models discussed in the literature. The non-equilibrium approach also reveals unexpected high-frequency dynamics not predicted by circuit models.Comment: 9 pages including 4 figures. Accepted for PRE

Iowa Swiss-type cheese

New types of cheese for Iowa have been receiving the attention of the Iowa Agricultural Experiment Station for a number of years. A previous publication (1) described the method of manufacture which has been used in the production of many thousands of pounds of Iowa Blue Cheese. This publication deals with the process used in the Iowa State College laboratories in manufacturing a Swiss-type cheese. In the course of these experiments a total of 25,136 lbs. of the cheese has been manufactured and marketed, utilizing approximately a quarter of a million pounds of milk

Iowa blue cheese

Iowa is an importer of cheese. In 1933 Iowa dairy plants manufactured 1,491,822 pounds of cheese.2 In the same year consumption is estimated to have been 10,254,397 pounds, using the 1933 United States Department of Agriculture figure of 4.15 pounds per capita and 1930 Iowa census figures as a basis of computation. In 1933 Iowa dairy plants produced 14.6 percent of the cheese consumed in the state. If this percentage could be greatly increased it would result in a larger and more diversified market for Iowa milk. Production of cured cheese in Iowa has up to the present consisted almost entirely of the staple variety known as Cheddar or American cheese. Small production has not been the result either of lack of milk or of inability to produce an acceptable cheese. Rather it has been the inability of the average dairy plant to pay enough more for milk to be used for cheesemaking to divert the milk from other manufacturing uses, principally butter. The high value placed by the Iowa farmer upon skimmilk for feeding purposes when used as a supplement to corn in hog production has undoubtedly been one important factor in limiting the production of cheese. When milk is made into cheese the skimmilk is not available for feeding on the farm. Instead, whey, which is estimated to possess half the value of skimmilk, is available for the feeding operations. This and other factors require that the dairy plants must be able to pay a substantially higher price for milk fat for cheesemaking than for buttermaking if milk is to be available for the former. Expansion of cheese production in Iowa apparently depends upon some method of increasing the returns which can be obtained from cheese so that a relatively larger payment can be made to the milk producer

Frequency response in surface-potential driven electro-hydrodynamics

Using a Fourier approach we offer a general solution to calculations of slip velocity within the circuit description of the electro-hydrodynamics in a binary electrolyte confined by a plane surface with a modulated surface potential. We consider the case with a spatially constant intrinsic surface capacitance where the net flow rate is in general zero while harmonic rolls as well as time-averaged vortex-like components may exist depending on the spatial symmetry and extension of the surface potential. In general the system displays a resonance behavior at a frequency corresponding to the inverse RC time of the system. Different surface potentials share the common feature that the resonance frequency is inversely proportional to the characteristic length scale of the surface potential. For the asymptotic frequency dependence above resonance we find a 1/omega^2 power law for surface potentials with either an even or an odd symmetry. Below resonance we also find a power law omega^alpha with alpha being positive and dependent of the properties of the surface potential. Comparing a tanh potential and a sech potential we qualitatively find the same slip velocity, but for the below-resonance frequency response the two potentials display different power law asymptotics with alpha=1 and alpha~2, respectively.Comment: 4 pages including 1 figure. Accepted for PR

Revitalizing the Retail Trade Sector in Rural Communities: Experiences of 13 North Dakota Towns

Community/Rural/Urban Development,

'Raising the bar' : improving the standard and utility of weed and invasive plant research

Fil: Murray, Justine V.. Water for Healthy Country Flagship; AustraliaFil: Lehnhoff, Erik A.. Montana State University; Estados UnidosFil: Neve, Paul. University of Warwick; Reino UnidoFil: Poggio, Santiago Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía; ArgentinaFil: Webber, Bruce L.. CSIRO Ecosystems Sciences; Australia. The University of Western Australia; Australi

Coulomb Drag in Coherent Mesoscopic Systems

We present a theory for Coulomb drag between two mesoscopic systems. Our formalism expresses the drag in terms of scattering matrices and wave functions, and its range of validity covers both ballistic and disordered systems. The consequences can be worked out either by analytic means, such as the random matrix theory, or by numerical simulations. We show that Coulomb drag is sensitive to localized states, which usual transport measurements do not probe. For chaotic 2D-systems we find a vanishing average drag, with a nonzero variance. Disordered 1D-wires show a finite drag, with a large variance, giving rise to a possible sign change of the induced current.Comment: 4 pages including 2 figures. Minor changes. Accepted for publication in Phys. Rev. Let