Discriminant Analysis; Telecommunications and Economic Development; Taking a Stand: Extension and Public Policy Issues

Reviews of Discriminant Analysis, by William R. Klecka; Telecommunications and Economic Development by Robert J. Saunders, Jeremy J. Warford, and Bjorn Wellenius; Taking a Stand: Extension and Public Policy Issues, by Richard L. Barrows

Second harmonic generating (SHG) nanoprobes for in vivo imaging

Fluorescence microscopy has profoundly changed cell and molecular biology studies by permitting tagged gene products to be followed as they function and interact. The ability of a fluorescent dye to absorb and emit light of different wavelengths allows it to generate startling contrast that, in the best cases, can permit single molecule detection and tracking. However, in many experimental settings, fluorescent probes fall short of their potential due to dye bleaching, dye signal saturation, and tissue autofluorescence. Here, we demonstrate that second harmonic generating (SHG) nanoprobes can be used for in vivo imaging, circumventing many of the limitations of classical fluorescence probes. Under intense illumination, such as at the focus of a laser-scanning microscope, these SHG nanocrystals convert two photons into one photon of half the wavelength; thus, when imaged by conventional two-photon microscopy, SHG nanoprobes appear to generate a signal with an inverse Stokes shift like a fluorescent dye, but with a narrower emission. Unlike commonly used fluorescent probes, SHG nanoprobes neither bleach nor blink, and the signal they generate does not saturate with increasing illumination intensity. The resulting contrast and detectability of SHG nanoprobes provide unique advantages for molecular imaging of living cells and tissues

Time-resolved impulse response of the magnetoplasmon resonance in a two-dimensional electron gas

We have used optically excited ultrashort electrical pulses to measure the magnetoplasmon resonance of a two-dimensional electron gas formed in an AlGaAs/GaAs heterostructure at frequencies up to 200 gigahertz. This is accomplished by incorporating the sample into a guided wave probe operating in a pumped (^{3}He) system. We are able to detect the resonance by launching a stimulus pulse in the guide, and monitoring the system response in a time resolved pump-probe arrangement. Data obtained from measurements yield resonant frequencies that agree with the magnetoplasmon dispersion relation.Comment: 4 pages, 4 figure

Herbicide-resistant weeds : from research and knowledge to future needs

Synthetic herbicides have been used globally to control weeds in major field crops. This has imposed a strong selection for any trait that enables plant populations to survive and reproduce in the presence of the herbicide. Herbicide resistance in weeds must be minimized because it is a major limiting factor to food security in global agriculture. This represents a huge challenge that will require great research efforts to develop control strategies as alternatives to the dominant and almost exclusive practice of weed control by herbicides. Weed scientists, plant ecologists and evolutionary biologists should join forces and work towards an improved and more integrated understanding of resistance across all scales. This approach will likely facilitate the design of innovative solutions to the global herbicide resistance challenge

Pennsylvania Folklife Vol. 14, No. 1

• The Oley Valley Basketmaker • The Sheen of Copper • Pennsylvania Corncribs • Land-Clearing in Lycoming County, Pennsylvania • Funerals in My Childhood Days • Folk Medicine from Western Pennsylvania • Peddlers I Rememberhttps://digitalcommons.ursinus.edu/pafolklifemag/1017/thumbnail.jp

Pennsylvania Folklife Vol. 27, Folk Festival Supplement

• Hex Signs: A Living Tradition • Decoys and How to Make Them • Kutztown\u27s Plain People • The Old Country Kitchen: Where Food Preparation was an Art • Wooden Toys, Games and Puzzles: The Delight of All Children • A Sketch of the Seminar Stage Programs • Festival Focus • Folk Festival Programs • The Furniture-Makers at the Kutztown Festival • The Muzzle-Loading Gunsmith • Those Rare Things Called Antiques! • Mouth-Watering Baked Goods, Fresh From the Ovens! • The Art of the Potterhttps://digitalcommons.ursinus.edu/pafolklifemag/1079/thumbnail.jp

A high precision, compact electromechanical ground rotation sensor

We present a mechanical rotation sensor consisting of a balance pivoting on a tungsten carbide knife edge. These sensors are important for precision seismic isolation systems, as employed in land-based gravitational wave interferometers and for the new field of rotational seismology. The position sensor used is an air-core linear variable differential transformer with a demonstrated noise floor of 1×10^(−11)m/√Hz. We describe the instrument construction and demonstrate low noise operation with a noise floor upper bound of 5.7×10^(−9)rad/√Hz at 10 mHz and 6.4×10^(−10)rad/√Hz at 0.1 Hz. The performance of the knife edge hinge is compatible with a behaviorur free of noise from dislocation self-organized criticality