3,411 research outputs found

    Halting Neotropical Deforestation: Do the Forest Principles Have What It Takes?

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    INTRODUCTION I crashed into the thick secondary growth, stopping suddenly to duck a certain branch in my path: a fat black bullet ant crawled along it with indifference, an attitude that would have quickly changed had I brushed up against him. I headed toward the large patch of Heliconia just to the right. We had earlier mapped out the clump, and finding it to contain seventeen flower clusters, it was one of the prize patches in the study plot. I took my spot ten paces from the outer clusters, started my stop watch, and waited with field book in hand. The Birds of Paradise were dripping nectar from their red fingertips. With such a gold mine, I did not have to wait long for a hummingbird. Like an Evinrude-powered flat bottom whizzing up a winding lagoon, the bird\u27s sound reached me before I saw him. He appeared from the back of the patch, taking a drink here, then there, then here again, then at some other spot, then there again and back to here. He did not sit and sip for long at each spot, but he did pause long enough for me to see him gleam green and deep violet. He was a red-footed plumeleteer, emerald green on the head, changing to dark purple through his body and on to his tail. His feet and straight bill were distinctively red. Without a doubt he owned this lucrative Heliconia patch. But then from my right came another whir. A ..

    Labeling Fruits and Vegetables for Sale in Ohio

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    Classification of lower extremity movement patterns based on visual assessment: reliability and correlation with 2-dimensional video analysis

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    CONTEXT: Abnormal movement patterns have been implicated in lower extremity injury. Reliable, valid, and easily implemented assessment methods are needed to examine existing musculoskeletal disorders and investigate predictive factors for lower extremity injury. OBJECTIVE: To determine the reliability of experienced and novice testers in making visual assessments of lower extremity movement patterns and to characterize the construct validity of the visual assessments. DESIGN: Cross-sectional study. SETTING: University athletic department and research laboratory. PATIENTS OR OTHER PARTICIPANTS: Convenience sample of 30 undergraduate and graduate students who regularly participate in athletics (age = 19.3 ± 4.5 years). Testers were 2 experienced physical therapists and 1 novice postdoctoral fellow (nonclinician). MAIN OUTCOME MEASURE(S): We took videos of 30 athletes performing the single-legged squat. Three testers observed the videos on 2 occasions and classified the lower extremity movement as dynamic valgus, no change, or dynamic varus. The classification was based on the estimated change in frontal-plane projection angle (FPPA) of the knee from single-legged stance to maximum single-legged squat depth. The actual FPPA change was measured quantitatively. We used percentage agreement and weighted κ to examine tester reliability and to determine construct validity of the visual assessment. RESULTS: The κ values for intratester and intertester reliability ranged from 0.75 to 0.90, indicating substantial to excellent reliability. Percentage agreement between the visual assessment and the quantitative FPPA change category was 90%, with a κ value of 0.85. CONCLUSIONS: Visual assessments were made reliably by experienced and novice testers. Additionally, movement-pattern categories based on visual assessments were in excellent agreement with objective methods to measure FPPA change. Therefore, visual assessments can be used in the clinic to assess movement patterns associated with musculoskeletal disorders and in large epidemiologic studies to assess the association between lower extremity movement patterns and musculoskeletal injury

    Multiplexed Readout of Transmon Qubits with Josephson Bifurcation Amplifiers

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    Achieving individual qubit readout is a major challenge in the development of scalable superconducting quantum processors. We have implemented the multiplexed readout of a four transmon qubit circuit using non-linear resonators operated as Josephson bifurcation amplifiers. We demonstrate the simultaneous measurement of Rabi oscillations of the four transmons. We find that multiplexed Josephson bifurcation is a high-fidelity readout method, the scalability of which is not limited by the need of a large bandwidth nearly quantum-limited amplifier as is the case with linear readout resonators.Comment: 7 pages, 6 figures, and 31 reference

    Charm and Beauty in Particle Physics

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    The spectra of states containing charmed and beauty quarks, and their regularities, are reviewed.Comment: 29 pages, LaTeX, 10 EPSF figures submitted separately. Presented at CERN in September, 1994 at a symposium in honor of Andre Martin To be submitted to Comments on Nuclear and Particle Physic

    Fission decay of N = Z nuclei at high angular momentum: 60^{60}Zn

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    Using a unique two-arm detector system for heavy ions (the BRS, binary reaction spectrometer) coincident fission events have been measured from the decay of 60^{60}Zn compound nuclei formed at 88MeV excitation energy in the reactions with 36^{36}Ar beams on a 24^{24}Mg target at Elab(36E_{lab}(^{36}Ar) = 195 MeV. The detectors consisted of two large area position sensitive (x,y) gas telescopes with Bragg-ionization chambers. From the binary coincidences in the two detectors inclusive and exclusive cross sections for fission channels with differing losses of charge were obtained. Narrow out-of-plane correlations corresponding to coplanar decay are observed for two fragments emitted in binary events, and in the data for ternary decay with missing charges from 4 up to 8. After subtraction of broad components these narrow correlations are interpreted as a ternary fission process at high angular momentum through an elongated shape. The lighter mass in the neck region consists dominantly of two or three-particles. Differential cross sections for the different mass splits for binary and ternary fission are presented. The relative yields of the binary and ternary events are explained using the statistical model based on the extended Hauser-Feshbach formalism for compound nucleus decay. The ternary fission process can be described by the decay of hyper-deformed states with angular momentum around 45-52 hbarhbar.Comment: 23 pages, 25 figure

    Pauli problem for a spin of arbitrary length: A simple method to determine its wave function

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    The problem of determining a pure state vector from measurements is investigated for a quantum spin of arbitrary length. Generically, only a finite number of wave functions is compatible with the intensities of the spin components in two different spatial directions, measured by a Stern-Gerlach apparatus. The remaining ambiguity can be resolved by one additional well-defined measurement. This method combines efficiency with simplicity: only a small number of quantities have to be measured and the experimental setup is elementary. Other approaches to determine state vectors from measurements, also known as the ‘‘Pauli problem,’’ are reviewed for both spin and particle systems

    Aeronautical Ad Hoc Network for Civil Aviation

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    Aeronautical communication systems are constantly evolving in order to handle the always increasing flow of data generated by civil aviation. In this article we first present communication systems currently used for en-route aircraft. We then propose Aeronautical Ad hoc NETwork (AANET) as a complementary communication system and demonstrate its connectivity and assess the throughput by simulations based on real aircraft trajectories over the French sky and over the Atlantic ocean
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