1,035 research outputs found

    Applications of active microwave imagery

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    The following topics were discussed in reference to active microwave applications: (1) Use of imaging radar to improve the data collection/analysis process; (2) Data collection tasks for radar that other systems will not perform; (3) Data reduction concepts; and (4) System and vehicle parameters: aircraft and spacecraft

    Femtosecond Laser-Produced Plasma X-Rays from Periodically Modulated Surface Targets

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    We have studied theoretically and experimentally the x-ray production above 1 keV from femtosecond laser plasmas generated on periodically modulated surface targets. Laser energy coupling to plasma surface waves has been modeled using a numerical differential method. Almost total absorption of incident laser radiation is predicted for optimized interaction conditions. Silicon gratings have been irradiated by a 120fs Ti:sapphire laser at irradiances in excess of 1016 W/cm2. X-ray intensities above 1.5 keV (K-shell lines) have been measured as a function of the incidence angle. Results show a distinct x-ray emission maximum for the first order diffraction angle and are in good qualitative agreement with our theoretical predictions

    Local modes, phonons, and mass transport in solid 4^4He

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    We propose a model to treat the local motion of atoms in solid 4^{4}He as a local mode. In this model, the solid is assumed to be described by the Self Consistent Harmonic approximation, combined with an array of local modes. We show that in the bcc phase the atomic local motion is highly directional and correlated, while in the hcp phase there is no such correlation. The correlated motion in the bcc phase leads to a strong hybridization of the local modes with the T1(110)_{1}(110) phonon branch, which becomes much softer than that obtained through a Self Consistent Harmonic calculation, in agreement with experiment. In addition we predict a high energy excitation branch which is important for self-diffusion. Both the hybridization and the presence of a high energy branch are a consequence of the correlation, and appear only in the bcc phase. We suggest that the local modes can play the role in mass transport usually attributed to point defects (vacancies). Our approach offers a more overall consistent picture than obtained using vacancies as the predominant point defect. In particular, we show that our approach resolves the long standing controversy regarding the contribution of point defects to the specific heat of solid 4^{4}He.Comment: 10 pages, 10 figure

    \u3cem\u3eHerschel\u3c/em\u3e Observations of the Centaurus Oluster - the Dynamics of Cold Gas in a Cool Core

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    Brightest cluster galaxies (BCGs) in the cores of galaxy clusters have distinctly different properties from other low-redshift massive ellipticals. The majority of the BCGs in cool-core clusters show signs of active star formation. We present observations of NGC 4696, the BCG of the Centaurus galaxy cluster, at far-infrared (FIR) wavelengths with theHerschel space telescope. Using the PACS spectrometer, we detect the two strongest coolants of the interstellar medium, [C II] at 157.74 μm and [O I] at 63.18 μm, and in addition [N II] at 121.90 μm. The [C II] emission is extended over a region of 7 kpc with a similar spatial morphology and kinematics to the optical Hα emission. This has the profound implication that the optical hydrogen recombination line, Hα, the optical forbidden lines, [N II] λ6583 Å, the soft X-ray filaments and the FIR [C II] line all have the same energy source. We also detect dust emission using the PACS and SPIRE photometers at all six wavebands. We perform a detailed spectral energy distribution fitting using a two-component modified blackbody function and find a cold 19-K dust component with mass 1.6 × 106 M⊙ and a warm 46-K dust component with mass 4.0 × 103 M⊙. The total FIR luminosity between 8 and 1000 μm is 7.5 × 108 L⊙, which using Kennicutt relation yields a low star formation rate of 0.13 M⊙ yr−1. This value is consistent with values derived from other tracers, such as ultraviolet emission. Combining the spectroscopic and photometric results together with optical Hα, we model emitting clouds consisting of photodissociation regions adjacent to ionized regions. We show that in addition to old and young stellar populations, there is another source of energy, such as cosmic rays, shocks or reconnection diffusion, required to excite the Hα and [C II] filaments

    Reliability of Bioelectrical Impedance Analysis for Estimating Whole‐Fish Energy Density and Percent Lipids

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    We evaluated bioelectrical impedance analysis (BIA) as a nonlethal means of predicting energy density and percent lipids for three fish species: Yellow perch Perca flavescens, walleye Sander vitreus, and lake whitefish Coregonus clupeaformis. Although models that combined BIA measures with fish wet mass provided strong predictions of total energy, total lipids, and total dry mass for whole fish, including BIA provided only slightly better predictions than using fish mass alone. Regression models that used BIA measures to directly predict the energy density or percent lipids of whole fish were generally better than those using body mass alone (based on Akaike’s information criterion). However, the goodness of fit of models that used BIA measures varied widely across species and at best explained only slightly more than one‐half the variation observed in fish energy density or percent lipids. Models that combined BIA measures with body mass for prediction had the strongest correlations between predicted and observed energy density or percent lipids for a validation group of fish, but there were significant biases in these predictions. For example, the models underestimated energy density and percent lipids for lipid‐rich fish and overestimated energy density and percent lipids for lipid‐poor fish. A comparison of observed versus predicted whole‐fish energy densities and percent lipids demonstrated that models that incorporated BIA measures had lower maximum percent error than models without BIA measures in them, although the errors for the BIA models were still generally high (energy density: 15‐18%; percent lipids: 82‐89%). Considerable work is still required before BIA can provide reliable predictions of whole‐fish energy density and percent lipids, including understanding how temperature, electrode placement, and the variation in lipid distribution within a fish affect BIA measures.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/141722/1/tafs1519.pd

    Immunohistochemical detection of macrophage migration inhibitory factor in fetal and adult bovine epididymis: Release by the apocrine secretion mode?

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    Originally defined as a lymphokine inhibiting the random migration of macrophages, the macrophage migration inhibitory factor (MIF) is an important mediator of the host response to infection. Beyond its function as a classical cytokine, MIF is currently portrayed as a multifunctional protein with growth-regulating properties present in organ systems beyond immune cells. In previous studies, we detected substantial amounts of MIF in the rat epididymis and epididymal spermatozoa, where it appears to play a role during post-testicular sperm maturation and the acquisition of fertilization ability. To explore its presence in other species not yet examined in this respect, we extended the range of studies to the bull. Using a polyclonal antibody raised against MIF purified from bovine eye lenses, we detected MIF in the epithelium of the adult bovine epididymis with the basal cells representing a prominently stained cell type. A distinct accumulation of MIF at the apical cell pole of the epithelial cells and in membranous vesicles localized in the lumen of the epididynnal duct was obvious. In the fetal bovine epididymis, we also detected MIF in the epithelium, whereas MIF accumulation was evident at the apical cell surface and in apical protrusions. By immuno-electron microscopy of the adult bovine epididymis, we localized MIF in apical protrusions of the epithelial cells and in luminal membrane-bound vesicles that were found in close proximity to sperm cells. Although the precise origin of the MIF-containing vesicles remains to be delineated, our morphological observations support the hypothesis that they become detached from the apical surface of the epididymal epithelial cells. Additionally, an association of MIF with the outer dense fibers of luminal spermatozoa was demonstrated. Data obtained in this study suggest MIF release by an apocrine secretion mode in the bovine epididymis. Furthermore, MIF localized in the basal cells of the epithelium and in the connective tissue could be responsible for regulating the migration of macrophages in order to avoid contact of immune cells with spermatozoa that carry a wide range of potent antigens. Copyright (c) 2006 S. Karger AG, Basel

    Involvement of RDR6 in short-range intercellular RNA silencing in Nicotiana benthamiana

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    In plants, non-cell autonomous RNA silencing spreads between cells and over long distances. Recent work has revealed insight on the genetic and molecular components essential for cell-to-cell movement of RNA silencing in Arabidopsis. Using a local RNA silencing assay, we report on a distinct mechanism that may govern the short-range (6–10 cell) trafficking of virus-induced RNA silencing from epidermal to neighbouring palisade and spongy parenchyma cells in Nicotiana benthamiana. This process involves a previously unrecognised function of the RNA-dependent RNA polymerase 6 (RDR6) gene. Our data suggest that plants may have evolved distinct genetic controls in intercellular RNA silencing among different types of cells

    Bishops who live like princes: Bishop Tebartz-van Elst and the challenge of defining corruption

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    This article contributes to the debate on defining corruption. Rather than attempting to provide a definitive definition, it uses the case of Franz-Peter Tebartz-van Elst, a German bishop from the diocese of Limburg who stepped down in 2014, to illustrate that the disciplines of law, political science, economics, and anthropology all make important contributions to understanding what corruption is and how it should be conceptualized. Seen through these different lenses, the article argues, the case of “Bishop Bling” can be understood in strikingly different ways. This has ramifications not just for the case itself but also for how analysts understand corruption more broadly. Adopting an overtly interdisciplinary approach does not represent a way to “solve” the definitional dilemma, but it can help analysts understand more about corruption’s multiplicity
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