907 research outputs found

    Warranty Deed (Twitchell to Slavin) (1919)

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    Warranty Deed (Twitchell to Slavin) (1919) Warranty Deed from Emma P. Twitchell to Thomas Slavin, dated June 17, 1919. Property on Washington Street in Bath, Maine that will become the future site of the synagogue.https://digitalcommons.usm.maine.edu/jud_povich/1071/thumbnail.jp

    Low Power Microwave Signal Detection With a Spin-Torque Nano-Oscillator in the Active Self-Oscillating Regime

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    A spin-torque nano-oscillator (STNO) driven by a ramped bias current can perform spectrum analysis quickly over a wide frequency bandwidth. The STNO spectrum analyzer operates by injection locking to external microwave signals and produces an output DC voltage VdcV_{\rm dc} that temporally encodes the input spectrum. We found, via numerical analysis with a macrospin approximation, that an STNO is able to scan a 10 GHz10~\rm GHz bandwidth in less than 100 ns100~\rm ns (scanning rate RR exceeds 100 MHz/ns100~\rm MHz/ns). In contrast to conventional quadratic microwave detectors, the output voltage of the STNO analyzer is proportional to the amplitude of the input microwave signal IrfI_{\rm rf} with sensitivity S=dVdc/dIrf750 mV/mAS = dV_{\rm dc}/dI_{\rm rf} \approx 750~\rm mV/mA. The minimum detectable signal of the analyzer depends on the scanning rate RR and, at low R1 MHz/nsR \approx 1~\rm MHz/ns, is about 1 pW1~\rm pW.Comment: 5 pages, 5 figure

    Noise properties of a resonance-type spin-torque microwave detector

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    We analyze performance of a resonance-type spin-torque microwave detector (STMD) in the presence of noise and reveal two distinct regimes of STMD operation. In the first (high-frequency) regime the minimum detectable microwave power PminP_{\rm min} is limited by the low-frequency Johnson-Nyquist noise and the signal-to-noise ratio (SNR) of STMD is proportional to the input microwave power PRFP_{\rm RF}. In the second (low-frequency) regime PminP_{\rm min} is limited by the magnetic noise, and the SNR is proportional to PRF\sqrt{P_{\rm RF}}. The developed formalism can be used for the optimization of the practical noise-handling parameters of a STMD.Comment: 3 pages, 2 figure

    Ion‐scale structure in Mercury’s magnetopause reconnection diffusion region

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    The strength and time dependence of the electric field in a magnetopause diffusion region relate to the rate of magnetic reconnection between the solar wind and a planetary magnetic field. Here we use ~150 ms measurements of energetic electrons from the Mercury Surface, Space Environment, GEochemistry, and Ranging (MESSENGER) spacecraft observed over Mercury’s dayside polar cap boundary (PCB) to infer such small‐scale changes in magnetic topology and reconnection rates. We provide the first direct measurement of open magnetic topology in flux transfer events at Mercury, structures thought to account for a significant portion of the open magnetic flux transport throughout the magnetosphere. In addition, variations in PCB latitude likely correspond to intermittent bursts of ~0.3–3 mV/m reconnection electric fields separated by ~5–10 s, resulting in average and peak normalized dayside reconnection rates of ~0.02 and ~0.2, respectively. These data demonstrate that structure in the magnetopause diffusion region at Mercury occurs at the smallest ion scales relevant to reconnection physics.Key PointsEnergetic electrons at Mercury map magnetic topology at ~150 msFirst direct observation of flux transfer event open‐field topology at MercuryModulations of the reconnection rate at Mercury occur at ion kinetic scalesPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/133575/1/grl54476_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/133575/2/grl54476.pd

    Increasing doses of fiber do not influence short-term satiety or food intake and are inconsistently linked to gut hormone levels

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    Background: People who eat more fiber often have a lower body weight than people who eat less fiber. The mechanism for this relationship has been explained, in part, by increased satiety, which may occur as a result of changes in appetite-suppressing gut hormone levels, and decreases in food intake at subsequent meals. Objective: We hypothesized that increasing doses of mixed fiber, consumed in muffins for breakfast, would proportionally influence satiety, gut hormone levels, and subsequent food intake. Design: This was a randomized, double-blind, crossover study. Healthy men (n=10) and women (n=10) with a BMI of 24±2 (mean±SEM) participated in this study. Fasting subjects consumed a muffin with 0, 4, 8, or 12 g of mixed fibers and approximately 500 kcal. Visual analog scales rated hunger and satiety for 3 h; blood was drawn to measure ghrelin, glucagon-like peptide-1 (GLP-1), and peptide YY3–36 (PYY3–36) at various intervals; and food intake was measured at an ad libitum lunch. Results: Responses to satiety-related questions did not differ among treatments. However, despite lack of differences in satiety, gut hormone levels differed among treatments. Ghrelin was higher after the 12 g fiber dose than after the 4 and 8 g fiber doses. GLP-1 was higher after the 0 g fiber dose than after the 12 and 4 g fiber doses, and PYY3–36 did not differ among fiber doses. Food intake was also indistinguishable among doses. Conclusion: Satiety, gut hormone response, and food intake did not change in a dose-dependent manner after subjects consumed 0, 4, 8, and 12 g of mixed fiber in muffins for breakfast

    The Boundary Conditions of the Heliosphere: Photoionization Models Constrained by Interstellar and In Situ Data

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    The boundary conditions of the heliosphere are set by the ionization, density and composition of inflowing interstellar matter. Constraining the properties of the Local Interstellar Cloud (LIC) at the heliosphere requires radiative transfer ionization models. We model the background interstellar radiation field using observed stellar FUV and EUV emission and the diffuse soft X-ray background. We also model the emission from the boundary between the LIC and the hot Local Bubble (LB) plasma, assuming that the cloud is evaporating because of thermal conduction. We create a grid of models covering a plausible range of LIC and LB properties, and use the modeled radiation field as input to radiative transfer/thermal equilibrium calculations using the Cloudy code. Data from in situ observations of He^O, pickup ions and anomalous cosmic rays in the heliosphere, and absorption line measurements towards epsilon CMa were used to constrain the input parameters. A restricted range of assumed LIC HI column densities and LB plasma temperatures produce models that match all the observational constraints. The relative weakness of the constraints on N(HI) and T_h contrast with the narrow limits predicted for the H^O and electron density in the LIC at the Sun, n(H^0) = 0.19 - 0.20 cm^-3, and n(e) = 0.07 +/- 0.01 cm^-3. Derived abundances are mostly typical for low density gas, with sub-solar Mg, Si and Fe, possibly subsolar O and N, and S about solar; however C is supersolar. The interstellar gas at the Sun is warm, low density, and partially ionized, with n(H) = 0.23 - 0.27 cm^-3, T = 6300 K, X(H^+) ~ 0.2, and X(He^+) ~ 0.4. These results appear to be robust since acceptable models are found for substantially different input radiation fields. Our results favor low values for the reference solar abundances for the LIC composition.Comment: 14 pages, 4 figures, submitted to Astronomy & Astrophysics together with papers from the International Space Sciences Institute workshop on Interstellar Hydrogen in the Heliospher

    Mercury Orbiter: Report of the Science Working Team

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    The results are presented of the Mercury Orbiter Science Working Team which held three workshops in 1988 to 1989 under the auspices of the Space Physics and Planetary Exploration Divisions of NASA Headquarters. Spacecraft engineering and mission design studies at the Jet Propulsion Lab were conducted in parallel with this effort and are detailed elsewhere. The findings of the engineering study, summarized herein, indicate that spin stabilized spacecraft carrying comprehensive particles and fields experiments and key planetology instruments in high elliptical orbits can survive and function in Mercury orbit without costly sun shields and active cooling systems
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