2,301 research outputs found
Tracking a non-cooperative target using a Doppler radar wireless sensor network
Tracking or target localization is used in a wide range of important tasks from knowing when your flight will arrive to ensuring your mail is received on time. Tracking provides the location of resources enabling solutions to complex logistical problems. Wireless Sensor Networks (WSN) create new opportunities when applied to tracking, such as more flexible deployment and real-time information. When radar is used as the sensing element in a tracking WSN better results can be obtained; because radar has a comparatively larger range both in distance and angle to other sensors commonly used in WSNs. This allows for less nodes deployed covering larger areas, saving money. In this report I implement a tracking WSN platform similar to what was developed by Lim, Wang, and Terzis. This consists of several sensor nodes each with a radar, a sink node connected to a host PC, and a Matlab© program to fuse sensor data. I have re-implemented their experiment with my WSN platform for tracking a non-cooperative target to verify their results and also run simulations to compare. The results of these tests are discussed and some future improvements are proposed
IMPORTANCE OF THE NONLINEAR TIME SERIES ANALYSIS IN SPORTS
New possibilities for characterizing and discussing variability are obtained by means of nonlinear techniques of time series. Calculation of the fractal dimension allows determination of a measure of the degree of freedom. This fact is demonstrated using the example of standing balance. When the conditions are difficult the fractal dimension decreases. Another fact we discovered in a study of the breaststroke: When the load is increased the efficiency of the movement and the fractal dimension are also reduced
A high-reflectivity high-Q micromechanical Bragg-mirror
We report on the fabrication and characterization of a micromechanical
oscillator consisting only of a free-standing dielectric Bragg mirror with high
optical reflectivity and high mechanical quality. The fabrication technique is
a hybrid approach involving laser ablation and dry etching. The mirror has a
reflectivity of 99.6%, a mass of 400ng, and a mechanical quality factor Q of
approximately 10^4. Using this micromirror in a Fabry Perot cavity, a finesse
of 500 has been achieved. This is an important step towards designing tunable
high-Q high-finesse cavities on chip.Comment: 3 pages, 2 figure
Force-Velocity and Power Characteristics of Rat Soleus Muscle Fibers after Hindlimb Suspension
The effects of 1, 2, and 3 wk of Hindlimb Suspension (HS) on force-velocity and power characteristics of single rat soleus fibers were determined. After 1, 2, or 3 wk of HS, small fiber bundles were isolated, placed in skinning solution, and stored at -20 C until studied. Single fibers were isolated and placed between a motor arm and force transducer, functional properties were studied, and fiber protein content was subsequently analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Additional fibers were isolated from soleus of control and after 1 and 3 wk of HS, and fiber type distribution and myosin light chain stoichiometry were determined from SDS-PAGE analysis. After 1 wk of HS, percent type I fibers declined from 82 to 74%, whereas hybrid fibers increased from 10 to 18%. Percent fast type 11 fibers increased from 8% in control and 1 wk of HS to 26% by 3 wk of HS. Most fibers showed an increased unloaded maximal shortening velocity (V(sub 0)), but myosin heavy chain remained entirely slow type I. The mechanism for increased V(sub 0) is unknown. There was a progressive decrease in fiber diameter (14, 30, and 38%) and peak force (38, 56, and 63%) after 1, 2, and 3 wk of HS, respectively. One week of HS resulted in a shift of the force-velocity curve, and between 2 and 3 wk of HS the curve shifted further such that V(sub 0) was higher than control at all relative loads less than 45% peak isometric force. Peak absolute power output of soleus fibers progressively decreased through 2 wk of HS but showed no further change at 3 wk. The results suggest that between 2 and 3 wk the HS-induced alterations in the force-velocity relationship act to maintain the power output of single soleus fibers despite a continued reduction in fiber force
Self-cooling of a micro-mirror by radiation pressure
We demonstrate passive feedback cooling of a mechanical resonator based on
radiation pressure forces and assisted by photothermal forces in a high-finesse
optical cavity. The resonator is a free-standing high-reflectance micro-mirror
(of mass m=400ng and mechanical quality factor Q=10^4) that is used as
back-mirror in a detuned Fabry-Perot cavity of optical finesse F=500. We
observe an increased damping in the dynamics of the mechanical oscillator by a
factor of 30 and a corresponding cooling of the oscillator modes below 10 K
starting from room temperature. This effect is an important ingredient for
recently proposed schemes to prepare quantum entanglement of macroscopic
mechanical oscillators.Comment: 11 pages, 9 figures, minor correction
Das Interpersonelle Aufmerksamkeitsmanagement-Inventar: Ein neues Instrument zur Erfassung unterschiedlicher Selbst- und Fremdwahrnehmungsfähigkeiten. = Interpersonal Attention Management Inventory: A New Instrument to Capture Different Self- and External Perception Skills
Hintergrund: Das Interpersonelle Aufmerksamkeitsmanagement-Inventar (IAMI) stellt ein neues Instrument zur Erfassung der Kompetenz in Selbst- und Fremdwahrnehmung dar. Ihm liegt ein theoretisches Modell bestehend aus den 3 mentalen Aufmerksamkeitsstandorten (intrapersoneller Raum, extrapersoneller Raum und fremder intrapersoneller Raum) einer anderen Person zugrunde. Methoden: Das IAMI wurde anhand einer größeren Stichprobe (n = 1089) hinsichtlich seiner Faktorenstruktur untersucht und gekürzt, und es wurden testtheoretische Kennwerte sowie erste Vergleichswerte berechnet. Ergebnisse: Eine Faktorenanalyse konnte die Einteilung in die übergeordneten Skalen weitgehend bestätigen. Die gekürzte Version mit 31 Items und 3 übergeordneten Skalen weist eine gute interne Konsistenz des Gesamtwertes (Cronbachs α = 0,81) auf und zeigt hinsichtlich der konvergenten Validität einen mittleren Zusammenhang (r = 0,41) des Gesamtwertes mit Achtsamkeit, gemessen mit dem Freiburger Fragebogen zur Achtsamkeit. Schlussfolgerungen: Weitere Validierungsstudien sind erwünscht, sodass das IAMI als (Verlaufs-)Diagnostikum für die Therapie psychischer Störungen sowie für die Forschung im Bereich der sozialen Neurowissenschaften eingesetzt werden kann, z.B. bei der Erforschung von Achtsamkeit, Mitgefühl, Empathie, der Theory-of-Mind und der Ich-Grenze
Migration of Zebrafish Primordial Germ Cells: A Role for Myosin Contraction and Cytoplasmic Flow
SummaryThe molecular and cellular mechanisms governing cell motility and directed migration in response to the chemokine SDF-1 are largely unknown. Here, we demonstrate that zebrafish primordial germ cells whose migration is guided by SDF-1 generate bleb-like protrusions that are powered by cytoplasmic flow. Protrusions are formed at sites of higher levels of free calcium where activation of myosin contraction occurs. Separation of the acto-myosin cortex from the plasma membrane at these sites is followed by a flow of cytoplasm into the forming bleb. We propose that polarized activation of the receptor CXCR4 leads to a rise in free calcium that in turn activates myosin contraction in the part of the cell responding to higher levels of the ligand SDF-1. The biased formation of new protrusions in a particular region of the cell in response to SDF-1 defines the leading edge and the direction of cell migration
Testing the equivalence principle: why and how?
Part of the theoretical motivation for improving the present level of testing
of the equivalence principle is reviewed. The general rationale for optimizing
the choice of pairs of materials to be tested is presented. One introduces a
simplified rationale based on a trichotomy of competing classes of theoretical
models.Comment: 11 pages, Latex, uses ioplppt.sty, submitted to Class. Quantum Gra
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