10,498 research outputs found

    Poetry: The Bananas that Move North

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    Poetry: A Star\u27s Biography

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    Upholding Liberty and Justice through the Virtue of Citizen Volunteerism

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    Alexis de Tocqueville observed that colonial Americans were preoccupied with civic duty, and he spoke to the beneficial power of early American volunteer associations which did not rely on government solutions. Colonial Americans resolved immediate communal needs through volunteerism and charity via civic and religious organizations. From de Tocqueville’s perspective, an essential element of being a good citizen was contributing to your community through volunteerism and charity. State and federal government overreach could be avoided by resolving local issues locally. The true nature of citizenship was to ensure liberty and justice through voluntary, philanthropic efforts and avoiding the mandated funding of government-sponsored programs through forced taxes. Communities benefit from hosting civic and charitable organizations, staffed by their own residents, to provide for the needs of those within their municipalities. For these organizations to be successful, they need volunteers with various skills to run business functions and financial donations in equal measure. Recent studies in American volunteerism support concepts of upholding liberty and justice through charity and volunteerism. This article will research American volunteerism, compare the successes and failures of various charitable organizations and the encroachment of governmental programs to replace these services, and offer suggestions for strengthening local volunteer participation levels in the future. In limiting government interventions through the virtues of volunteerism and charity, citizens can collectively use their individual skills and resources to ensure liberty by providing for their neighbors in need and nurturing their communities while promoting the Christian virtue to “love thy neighbor.

    Can dry merging explain the size evolution of early-type galaxies?

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    The characteristic size of early-type galaxies (ETGs) of given stellar mass is observed to increase significantly with cosmic time, from redshift z>2 to the present. A popular explanation for this size evolution is that ETGs grow through dissipationless ("dry") mergers, thus becoming less compact. Combining N-body simulations with up-to-date scaling relations of local ETGs, we show that such an explanation is problematic, because dry mergers do not decrease the galaxy stellar-mass surface-density enough to explain the observed size evolution, and also introduce substantial scatter in the scaling relations. Based on our set of simulations, we estimate that major and minor dry mergers increase half-light radius and projected velocity dispersion with stellar mass (M) as M^(1.09+/-0.29) and M^(0.07+/-0.11), respectively. This implies that: 1) if the high-z ETGs are indeed as dense as estimated, they cannot evolve into present-day ETGs via dry mergers; 2) present-day ETGs cannot have assembled more than ~45% of their stellar mass via dry mergers. Alternatively, dry mergers could be reconciled with the observations if there was extreme fine tuning between merger history and galaxy properties, at variance with our assumptions. Full cosmological simulations will be needed to evaluate whether this fine-tuned solution is acceptable.Comment: 5 pages, 2 figures. Accepted for publication in ApJ Letter

    Towards Laser Driven Hadron Cancer Radiotherapy: A Review of Progress

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    It has been known for about sixty years that proton and heavy ion therapy is a very powerful radiation procedure for treating tumours. It has an innate ability to irradiate tumours with greater doses and spatial selectivity compared with electron and photon therapy and hence is a tissue sparing procedure. For more than twenty years powerful lasers have generated high energy beams of protons and heavy ions and hence it has been frequently speculated that lasers could be used as an alternative to RF accelerators to produce the particle beams necessary for cancer therapy. The present paper reviews the progress made towards laser driven hadron cancer therapy and what has still to be accomplished to realise its inherent enormous potential.Comment: 40 pages, 24 figure

    Nose controls on delta wings at supersonic speeds

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    Expressions are derived for lÎľ and a2 of nose ailerons and nose elevators on a delta wing, as depicted in Fig. 1, in supersonic flight. Nose and trailing edge controls on delta wings in supersonic flight are compared

    The domestic policy of Robert Harley and the Tory Party from 1710 to 1714

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    This policy has been considered in special detail with regard to financial administration generally and Harley's achievements in the way of a revival of credit and trade particularly. The treatment of the commercial policy, inasmuch as it touches foreign policy, must necessarily be inadequate, since there exists an enormous mass of unexplored material concerned with the Utrecht negotiations. The chapter on spies, informers and pamphleteers, together with Appendix I, throws some interesting sidelights on the administration of Justice at this period, as well as bearing out what other writers have said on the main theme. The uncalendared State Papers Domestic reveal a wealth of information on these points. "Ministerial Relations and Intrigues" supports with intricate detail the theory that the Cabinet divisions were the essential cause of the 1714 debacle, while the chapter on the Church illustrates this point further, emphasises the immense political importance of that body and throws, perhaps, a new light on the relations between Harley, Harcourt and Atterbury. The Succession Question has been considered with regard first to the Stuarts and then to Hanover and the Ministry's relations with Marlborough. The conclusion drawn is that the Tories were not Jacobite. The trimming policy of Harley in Scotland and his essential non-Jacobitisim have been deduced from a variety of documents and other sources, the Portland Papers particularly illustrating the political, and the Treasury Papers the financial side of Harley's work. The chapter on Ireland has been based to a large extent on well-explored sources, but a close examination of these four years has again revealed Harley as ultimately a Trimmer, in his appointment of Phipps to build up the High church interest and his subsequent sending of Shrewsbury, too late, to mitigate the extremism that the Chancellor had provoked.<p

    The Structure & Dynamics of Massive Early-type Galaxies: On Homology, Isothermality and Isotropy inside one Effective Radius

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    Based on 58 SLACS strong-lens early-type galaxies with direct total-mass and stellar-velocity dispersion measurements, we find that inside one effective radius massive elliptical galaxies with M_eff >= 3x10^10 M_sun are well-approximated by a power-law ellipsoid with an average logaritmic density slope of = -dlog(rho_tot)/dlog(r)=2.085^{+0.025}_{-0.018} (random error on mean) for isotropic orbits with beta_r=0, +-0.1 (syst.) and sigma_gamma' <= 0.20^{+0.04}_{-0.02} intrinsic scatter (all errors indicate the 68 percent CL). We find no correlation of gamma'_LD with galaxy mass (M_eff), rescaled radius (i.e. R_einst/R_eff) or redshift, despite intrinsic differences in density-slope between galaxies. Based on scaling relations, the average logarithmic density slope can be derived in an alternative manner, fully independent from dynamics, yielding =1.959 +- 0.077. Agreement between the two values is reached for =0.45 +- 0.25, consistent with mild radial anisotropy. This agreement supports the robustness of our results, despite the increase in mass-to-light ratio with total galaxy mass: M_eff ~ L_{V,eff}^(1.363+-0.056). We conclude that massive early-type galaxies are structurally close-to homologous with close-to isothermal total density profiles (<=10 percent intrinsic scatter) and have at most some mild radial anisotropy. Our results provide new observational limits on galaxy formation and evolution scenarios, covering four Gyr look-back time.Comment: Accepted for publication by ApJL; 4 pages, 2 figure

    How cold is cold dark matter? Small scales constraints from the flux power spectrum of the high-redshift Lyman-alpha forest

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    We present constraints on the mass of warm dark matter (WDM) particles derived from the Lyman-alpha flux power spectrum of 55 high- resolution HIRES spectra at 2.0 < z < 6.4. From the HIRES spectra, we obtain a lower limit of mwdm > 1.2 keV 2 sigma if the WDM consists of early decoupled thermal relics and mwdm > 5.6 keV (2 sigma) for sterile neutrinos. Adding the Sloan Digital Sky Survey Lyman-alpha flux power spectrum, we get mwdm > 4 keV and mwdm > 28 keV (2 sigma) for thermal relics and sterile neutrinos. These results improve previous constraints by a factor two.Comment: Some issues clarified (especially resolution related). Conclusions unchanged. Accepted version by PR

    The Sloan Lens ACS Survey. IX. Colors, Lensing and Stellar Masses of Early-type Galaxies

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    We present the current photometric dataset for the Sloan Lens ACS (SLACS) Survey, including HST photometry from ACS, WFPC2, and NICMOS. These data have enabled the confirmation of an additional 15 grade `A' (certain) lens systems, bringing the number of SLACS grade `A' lenses to 85; including 13 grade `B' (likely) systems, SLACS has identified nearly 100 lenses and lens candidates. Approximately 80% of the grade `A' systems have elliptical morphologies while ~10% show spiral structure; the remaining lenses have lenticular morphologies. Spectroscopic redshifts for the lens and source are available for every system, making SLACS the largest homogeneous dataset of galaxy-scale lenses to date. We have developed a novel Bayesian stellar population analysis code to determine robust stellar masses with accurate error estimates. We apply this code to deep, high-resolution HST imaging and determine stellar masses with typical statistical errors of 0.1 dex; we find that these stellar masses are unbiased compared to estimates obtained using SDSS photometry, provided that informative priors are used. The stellar masses range from 10^10.5 to 10^11.8 M⊙_\odot and the typical stellar mass fraction within the Einstein radius is 0.4, assuming a Chabrier IMF. The ensemble properties of the SLACS lens galaxies, e.g. stellar masses and projected ellipticities, appear to be indistinguishable from other SDSS galaxies with similar stellar velocity dispersions. This further supports that SLACS lenses are representative of the overall population of massive early-type galaxies with M* >~ 10^11 M⊙_\odot, and are therefore an ideal dataset to investigate the kpc-scale distribution of luminous and dark matter in galaxies out to z ~ 0.5.Comment: 20 pages, 18 figures, 5 tables, published in Ap
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