378 research outputs found

    Parents And Children Thriving Together: A Framework For Two-Generation Policy And System Reform

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    This brief explores the lessons learned from the 2016 Parents and Children Thriving Together: Two Generation State Policy Network (PACTT Network), a collaboration between the National Governors Association (NGA) and the Center for Law and Social Policy (CLASP) with funding from the Doris Duke Charitable Foundation, W.K. Kellogg Foundation and the Annie E. Casey Foundation. Through this initiative, five states explored how to use the two-generation approach to improve their state systems that serve children and parents. This brief summarizes the lessons learned from the two-year initiative and provides a framework to help guide state leaders trying to implement two-generation strategies

    Variability of the Centimeter-Submillimeter Spectrum and Polarization of 3C 273 during Outburst

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    Original article can be found at: http://www.journals.uchicago.edu/ApJ/--Copyright University of Chicago Press/ AASCentimeter to submillimeter total flux and polarization monitoring data are used to investigate the nature of a prominent flare in the quasar 3C 273 during 1995/6. After removal of the quiescent level, the resulting “flare spectra" are well fitted by a simple homogeneous synchrotron source model, which in turn allows the movement of the self-absorption turnover to be tracked during the flare. Both the flare amplitude/time delay relationship and the overall spectral evolution are qualitatively consistent with existing models. The early evolution of the spectrum is best determined and is shown to be in excellent agreement with the Compton stage of the Marscher & Gear shock model. However, the polarization behavior during the flare is different at millimeter and centimeter wavelengths and the observations are difficult to reconcile with a simple transverse shock. They are, however, consistent with a conical shock for which the observed polarization properties vary with distance along the jet. Such variations may be caused, for example, by a change in cone angle owing to disruption caused by the growing component of the magnetic field parallel to the jet axis or by a moderate change in viewing angle.Peer reviewe

    Variability and polarization in the inner jet of 3C395

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    We present new results on the parsec-scale jet of the quasar 3C395, derived from VLBI polarization sensitive observations made in 1995.91 and 1998.50 at 8.4, 15.4 and 22.2 GHz. The observations show a complex one-sided jet extending up to 20 mas, with a projected magnetic field essentially aligned with the radio jet. The emission is strongly dominated, in total intensity and polarization, by the core and the inner jet region (of ~3 mas length). We have studied the details of this dominant region finding clear structural variations during this ~2.5 years period, in contrast with the apparent quietness of the jet structure inferred from lower resolution VLBI observations. We observe the ejection of a new component from the core and variations in the degree of polarization of the inner jet components. We estimate a high Faraday Rotation Measure close to the core, with a strong decrease along the inner jet.Comment: 7 pages, 4 figures, A&A in pres

    The magnetic field and geometry of the oblique shock in the jet of 3C 346

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    We investigate the brightest regions of the kpc-scale jet in the powerful radio galaxy 3C 346, using new optical HST ACS/F606W polarimetry together with Chandra X-ray data and 14.9 GHz and 22.5 GHz VLA radio polarimetry. The jet shows a close correspondence in optical and radio morphology, while the X-ray emission shows an 0.80 +/- 0.17 kpc offset from the optical and radio peak positions. Optical and radio polarimetry show the same apparent magnetic field position angle and fractional polarization at the brightest knot, where the jet undergoes a large kink of almost 70 degrees in the optical and radio images. The apparent field direction here is well-aligned with the new jet direction, as predicted by earlier work that suggested the kink was the result of an oblique shock. We have explored models of the polarization from oblique shocks to understand the geometry of the 3C 346 jet, and find that the upstream flow is likely to be highly relativistic (0.91 +0.05 / -0.07 c), where the plane of the shock front is inclined at an angle of 51 (+/- 11) degrees to the upstream flow which is at an angle 14 (+8 / -7) degrees to our line of sight. The actual deflection angle of the jet in this case is only 22 degrees.Comment: 11 pages, 5 figures. Accepted by MNRA

    Polarimetric Observations of 15 AGNs at High Frequencies

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    Original paper can be found at: http://www.astrosociety.org/pubs/cs/328.html--Copyright Astronomical Society of the PacificWe have obtained total and polarized intensity images of 15 AGNs with the VLBA at 7 mm at 17 epochs from 25/26 March 1998 to 14 April 2001. The VLBA observations are accompanied at many epochs by simultaneous mea- surements of polarization at 1.35/0.85 mm as well as less frequent simultaneous optical polarization measurements. We discuss the similarities and complexities of polarization behavior at different frequencies along with the VLBI properties

    Resonant-Cavity-Induced Phase Locking and Voltage Steps in a Josephson Array

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    We describe a simple dynamical model for an underdamped Josephson junction array coupled to a resonant cavity. From numerical solutions of the model in one dimension, we find that (i) current-voltage characteristics of the array have self-induced resonant steps (SIRS), (ii) at fixed disorder and coupling strength, the array locks into a coherent, periodic state above a critical number of active Josephson junctions, and (iii) when NaN_a active junctions are synchronized on an SIRS, the energy emitted into the resonant cavity is quadratic with NaN_a. All three features are in agreement with a recent experiment [Barbara {\it et al}, Phys. Rev. Lett. {\bf 82}, 1963 (1999)]}.Comment: 4 pages, 3 eps figures included. Submitted to PRB Rapid Com

    A caspase-3 'death-switch' in colorectal cancer cells for induced and synchronous tumor apoptosis in vitro and in vivo facilitates the development of minimally invasive cell death biomarkers

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    Novel anticancer drugs targeting key apoptosis regulators have been developed and are undergoing clinical trials. Pharmacodynamic biomarkers to define the optimum dose of drug that provokes tumor apoptosis are in demand; acquisition of longitudinal tumor biopsies is a significant challenge and minimally invasive biomarkers are required. Considering this, we have developed and validated a preclinical 'death-switch' model for the discovery of secreted biomarkers of tumour apoptosis using in vitro proteomics and in vivo evaluation of the novel imaging probe [ 18 F]ML-10 for non-invasive detection of apoptosis using positron emission tomography (PET). The 'death-switch' is a constitutively active mutant caspase-3 that is robustly induced by doxycycline to drive synchronous apoptosis in human colorectal cancer cells in vitro or grown as tumor xenografts. Deathswitch induction caused caspase-dependent apoptosis between 3 and 24 hours in vitro and regression of 'death-switched' xenografts occurred within 24 h correlating with the percentage of apoptotic cells in tumor and levels of an established cell death biomarker (cleaved cytokeratin-18) in the blood. We sought to define secreted biomarkers of tumor apoptosis from cultured cells using Discovery Isobaric Tag proteomics, which may provide candidates to validate in blood. Early after caspase-3 activation, levels of normally secreted proteins were decreased (e.g. Gelsolin and Midkine) and proteins including CD44 and High Mobility Group protein B1 (HMGB1) that were released into cell culture media in vitro were also identified in the bloodstream of mice bearing death-switched tumors. We also exemplify the utility of the death-switch model for the validation of apoptotic imaging probes using [ 18 F]ML-10, a PET tracer currently in clinical trials. Results showed increased tracer uptake of [ 18 F]ML-10 in tumours undergoing apoptosis, compared with matched tumour controls imaged in the same animal. Overall, the death-switch model represents a robust and versatile tool for the discovery and validation of apoptosis biomarkers. © 2013 Macmillan Publishers Limited. All rights reserved

    X-ray Properties of the GigaHertz-Peaked and Compact Steep Spectrum Sources

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    We present {\it Chandra} X-ray Observatory observations of Giga-Hertz Peaked Spectrum (GPS) and Compact Steep Spectrum (CSS) radio sources. The {\it Chandra} sample contains 13 quasars and 3 galaxies with measured 2-10 keV X-ray luminosity within 1042104610^{42} - 10^{46} erg s1^{-1}. We detect all of the sources, five of which are observed in X-ray for the first time. We study the X-ray spectral properties of the sample. The measured absorption columns in the quasars are different than those in the galaxies in the sense that the quasars show no absorption (with limits 1021cm2\sim 10^{21} \rm cm^{-2}) while the galaxies have large absorption columns (>1022cm2> 10^{22} \rm cm^{-2}) consistent with previous findings. The median photon index of the sources with high S/N is Γ=1.84±0.24\Gamma=1.84 \pm0.24 and it is larger than the typical index of radio loud quasars. The arcsec resolution of {\it Chandra} telescope allows us to investigate X-ray extended emission, and look for diffuse components and X-ray jets. We found X-ray jets in two quasars (PKS 1127-145, B2 0738+32), an X-ray cluster surrounding a CSS quasar (z=1.1, 3C 186), detected a possible binary structure in 0941-080 galaxy and an extended diffuse emission in galaxy PKS B2 1345+12. We discuss our results in the context of X-ray emission processes and radio source evolution. We conclude that the X-ray emission in these sources is most likely unrelated to a relativistic jet, while the sources' radio-loudness may suggest a high radiative efficiency of the jet power in these sources.Comment: 15 pages, to be published in Ap

    Dynamics of a Josephson Array in a Resonant Cavity

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    We derive dynamical equations for a Josephson array coupled to a resonant cavity by applying the Heisenberg equations of motion to a model Hamiltonian described by us earlier [Phys. Rev. B {\bf 63}, 144522 (2001); Phys. Rev. B {\bf 64}, 179902 (E)]. By means of a canonical transformation, we also show that, in the absence of an applied current and dissipation, our model reduces to one described by Shnirman {\it et al} [Phys. Rev. Lett. {\bf 79}, 2371 (1997)] for coupled qubits, and that it corresponds to a capacitive coupling between the array and the cavity mode. From extensive numerical solutions of the model in one dimension, we find that the array locks into a coherent, periodic state above a critical number of active junctions, that the current-voltage characteristics of the array have self-induced resonant steps (SIRS's), that when NaN_a active junctions are synchronized on a SIRS, the energy emitted into the resonant cavity is quadratic in NaN_a, and that when a fixed number of junctions is biased on a SIRS, the energy is linear in the input power. All these results are in agreement with recent experiments. By choosing the initial conditions carefully, we can drive the array into any of a variety of different integer SIRS's. We tentatively identify terms in the equations of motion which give rise to both the SIRS's and the coherence threshold. We also find higher-order integer SIRS's and fractional SIRS's in some simulations. We conclude that a resonant cavity can produce threshold behavior and SIRS's even in a one-dimensional array with appropriate experimental parameters, and that the experimental data, including the coherent emission, can be understood from classical equations of motion.Comment: 15 pages, 10 eps figures, submitted to Phys. Rev.

    Eigenstates of a Small Josephson Junction Coupled to a Resonant Cavity

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    We carry out a quantum-mechanical analysis of a small Josephson junction coupled to a single-mode resonant cavity. We find that the eigenstates of the combined junction-cavity system are strongly entangled only when the gate voltage applied at one of the superconducting islands is tuned to certain special values. One such value corresponds to the resonant absorption of a single photon by Cooper pairs in the junction. Another special value corresponds to a {\em two-photon} absorption process. Near the single-photon resonant absorption, the system is accurately described by a simplified model in which only the lowest two levels of the Josephson junction are retained in the Hamiltonian matrix. We noticed that this approximation does not work very well as the number of photons in the resonator increases. Our system shows also the phenomenon of ``collapse and revival'' under suitable initial conditions, and our full numerical solution agrees with the two level approximation result.Comment: 7 pages, and 6 figures. To be published in Phys. Rev.
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