Video sensor with range measurement capability

A video sensor device is provided which incorporates a rangefinder function. The device includes a single video camera and a fixed laser spaced a predetermined distance from the camera for, when activated, producing a laser beam. A diffractive optic element divides the beam so that multiple light spots are produced on a target object. A processor calculates the range to the object based on the known spacing and angles determined from the light spots on the video images produced by the camera

Stopping Light on a Defect

Gap solitons are localized nonlinear coherent states which have been shown both theoretically and experimentally to propagate in periodic structures. Although theory allows for their propagation at any speed $v$, $0\le v\le c$, they have been observed in experiments at speeds of approximately 50% of $c$. It is of scientific and technological interest to trap gap solitons. We first introduce an explicit multiparameter family of periodic structures with localized defects, which support linear defect modes. These linear defect modes are shown to persist into the nonlinear regime, as {\it nonlinear defect modes}. Using mathematical analysis and numerical simulations we then investigate the capture of an incident gap soliton by these defects. The mechanism of capture of a gap soliton is resonant transfer of its energy to nonlinear defect modes. We introduce a useful bifurcation diagram from which information on the parameter regimes of gap soliton capture, reflection and transmission can be obtained by simple conservation of energy and resonant energy transfer principles.Comment: 45 pages, Submitted to Journal of the Optical Society

Detection of pulsar beams deflected by the black hole in Sgr A*: effects of black hole spin

Some Galactic models predict a significant population of radio pulsars close to the our galactic center. Beams from these pulsars could get strongly deflected by the supermassive black hole (SMBH) believed to reside at the galactic center and reach the Earth. Earlier work assuming a Schwarzschild SMBH gave marginal chances of observing this exotic phenomenon with current telescopes and good chances with future telescopes. Here we calculate the odds of observability for a rotating SMBH. We find that the estimates of observation are not affected by the SMBH spin, but a pulsar timing analysis of deflected pulses might be able to provide an estimate of the spin of the central black hole.Comment: 15 pages aastex, 8 Fig

Civil and Mechanical Engineering Students Learning Mechanics in a Multidisciplinary Engineering Foundation Spiral

This paper describes how mechanical and civil engineering students are introduced to and develop an understanding of mechanics concepts through a sequence of integrated courses as part of a new curriculum taken during the freshman and sophomore years. The Multi- Disciplinary Engineering Foundation Spiral is a four-semester sequence of engineering courses, matched closely with the development of students’ mathematical sophistication and analytical capabilities and integrated with course work in the sciences. Students develop a conceptual understanding of engineering basics in this series of courses, which stress practical applications of these principles. Mechanics concepts are introduced in a pair of first year courses, EAS107P, Project-Based Introduction to Engineering and EAS112, Methods of Engineering Analysis. During the second year, students’ understanding of these concepts is further developed in three courses, two offered during the fall semester, EAS211, Introduction to Modeling of Engineering Systems and EAS213, Materials in Engineering Systems and one during the spring semester, EAS222, Fundamentals of Mechanics and Materials. In the third semester of discipline specific classes, ME300 Rigid Body Dynamics and CE312 Structural Analysis for mechanical and civil engineering respectively, students are evaluated compared to their peers who have either transferred in from other universities or taken a previous traditional sequence of mechanics courses. The first course, EAS107P, introduces students to concepts related to structural systems and trusses, such as internal and external forces, reactions, compression and tension. This is done in the context of a team project in which students gain a qualitative understanding of these concepts using computer simulation models. In the second course EAS112, students use computer tools such as spreadsheets to solve problems including the analysis of trusses. Mechanics of materials are explored as students use spreadsheets to analyze tensile test properties. In the second year, resolution of forces is further developed in EAS211 as students use force balances to solve various statics problems. Students study the properties, behavior and application of materials in EAS213, including discussion of such concepts as torsion, compression, tension, fatigue, creep and fracture. This course focuses on the differences between materials and selection of materials for engineering applications. In EAS222, students develop an understanding of the basic principles and applications of engineering mechanics including the behavior of structures under various loads, bending and Mohr’s circle. This paper discusses how the mechanics topics are threaded through this sequence of courses and how mastery of these topics is being assessed at the disciplinary level in the junior year. Assessment of students’ understanding of mechanics topics includes the following instruments: data drawn from quiz/exam grades and/or particular question(s) on exams/quizzes related to specific concepts; and faculty observations gathered using a survey tool. Our current data evaluates the first group of students to reach the junior level in the new curriculum that was implemented during the 2004-05 academic year

A Radio Survey for Linear and Circular Polarization in Low Luminosity Active Galactic Nuclei

We conducted a Very Large Array survey of eleven low luminosity active galactic nuclei for linear and circular polarization at 8.4 GHz. We detected circular polarization in one source (M81*) and linear polarization in 3 sources. Sensitivity limits were ~0.1% for both modes of polarization in 9 of 11 sources. The detections confirm the importance of nonthermal emission in LLAGN. However, detection rates for circular and linear polarization are lower for these sources than for more powerful AGN. Fractional linear polarization in detected sources is also lower than in more powerful AGN. The weak linear polarization in the survey sources indicates their overall similarity to Sgr A*. Confusion with thermal sources, depolarization and weaker, less extended jets may contribute to these differences. We detect a rotation measure >~ 7 x 10^4 rad m^-2 for NGC 4579. This may arise from magnetized plasma in the accretion, outflow or interstellar regions. Inverted spectra are present in both M81* and Sagittarius A* and absent from all sources in which circular polarization is not detected. This suggests that optical depth effects are important in the creation of circular polarization.Comment: 12 pages, 2 figures, accepted for publication in ApJ

Range-Measuring Video Sensors

Optoelectronic sensors of a proposed type would perform the functions of both electronic cameras and triangulation- type laser range finders. That is to say, these sensors would both (1) generate ordinary video or snapshot digital images and (2) measure the distances to selected spots in the images. These sensors would be well suited to use on robots that are required to measure distances to targets in their work spaces. In addition, these sensors could be used for all the purposes for which electronic cameras have been used heretofore. The simplest sensor of this type, illustrated schematically in the upper part of the figure, would include a laser, an electronic camera (either video or snapshot), a frame-grabber/image-capturing circuit, an image-data-storage memory circuit, and an image-data processor. There would be no moving parts. The laser would be positioned at a lateral distance d to one side of the camera and would be aimed parallel to the optical axis of the camera. When the range of a target in the field of view of the camera was required, the laser would be turned on and an image of the target would be stored and preprocessed to locate the angle (a) between the optical axis and the line of sight to the centroid of the laser spot

From Digitalis to Ziagen: The University of Minnesota's Department of Medicinal Chemistry

A comprehensive history of Medicinal Chemistry beginning with the founding of the University of Minnesota’s College of Pharmacy in 1892 until today. In turn that same period of time—1892 to 2012—also represents the most revolutionary era in the history of the entire discipline of medicinal chemistry, witnessing the transformation of the field from an artisanal, trial-and-error approach to isolating and testing therapeutic elements in natural elements to today’s high-tech, computer-assisted discovery and design of new, targeted drugs.Department of Medicinal Chemistr

Observability of pulsar beam bending by the Sgr~A* black hole

According to some models, there may be a significant population of radio pulsars in the Galactic center. In principle, a beam from one of these pulsars could pass close to the supermassive black hole (SMBH) at the center, be deflected, and be detected by Earth telescopes. Such a configuration would be an unprecedented probe of the properties of spacetime in the moderate- to strong-field regime of the SMBH. We present here background on the problem, and approximations for the probability of detection of such beams. We conclude that detection is marginally probable with current telescopes, but that telescopes that will be operating in the near future, with an appropriate multiyear observational program, will have a good chance of detecting a beam deflected by the SMBH.Comment: 18 pages, 16 figure

Effect of Alfalfa Silage Storage Structure and Roasting Corn on Production and Ruminal Metabolism of Lactating Dairy Cows

Abstract The objective of this study was to determine if feeding roasted corn would improve production and nutrient utilization when supplemented to lactating cows fed 1 of 3 different alfalfa silages (AS). Forty-two lactating Holstein cows (6 fitted with ruminal cannulas) averaging 77 d in milk and 43kg of milk/d pretrial were assigned to 2 cyclic changeover designs. Treatments were AS ensiled in bag, bunker, or O 2 -limiting tower silos and supplemented with ground shelled corn (GSC) or roasted GSC (RGSC). Silages were prepared from second-cutting alfalfa, field-wilted an average of 24h, and ensiled over 2 d. Production and N utilization were evaluated in 36 cows during four 28-d periods, and ruminal fermentation was evaluated with 6 cows during five 21-d periods. Experimental diets contained 40% AS, 15% corn silage, and 35% of either GSC or RGSC on a dry matter basis. No significant interactions between AS and corn sources were detected for any production trait. Although the chemical composition of the 3 AS was similar, feeding AS from the O 2 -limited tower silo elicited positive production responses. Yields of 3.5% fat-corrected milk and fat were increased 1.7kg/d and 150g/d, and milk fat content was increased 0.3% when cows were fed diets based on AS from the O 2 -limiting silo compared with the other 2 silages. The responses in milk fat were paralleled by an average increase in acid detergent fiber digestibility of 270g/d for cows fed AS from the O 2 -limiting tower silo. However, ruminal concentrations of lipogenic volatile fatty acids were unchanged with AS source. Cows fed RGSC consumed 0.6kg/d more dry matter and yielded 30g/d more protein and 50g/d more lactose than cows fed GSC diets. There was no evidence of increased total tract digestibility of organic matter or starch, or reduced ruminal NH 3 concentration, when feeding RGSC. Free amino acids increased, and isovalerate decreased in rumen fluid from cows fed RGSC diets. However, responses in production with roasted corn were mainly due to increased dry matter intake, which increased the supply of energy and nutrients available for synthesis of milk and milk components