The Case for Dynamic Cities

Cities today are confronting never-before-seen challenges to their top spot in the economic hierarchy. In this chapter, we lay out four challenges, past and future, that cities face today and identify policies that can help address the problems we identify. We call attention to the need for many U.S. cities to redevelop the large amount of aging postwar single-family housing, while reforming past exclusionary zoning and infrastructure decisions that exacerbated inequality. Cities will have to fix these past mistakes against the backdrop of an aging population and the rise of remote working, both of which undercut cities’ traditional source of growth by reducing the flow of younger and middle-aged people willing to live in urban centers. The common theme running throughout this paper is that cities, their residents and their business leaders will need to embrace a dynamic ethos and be given a freer hand to reposition their municipalities to face a future that is shaping up to be quite different from the past

Meta-análisis de la historia del estudio de las tortugas continentales de Colombia

Analizamos las referencias incluidas en una reciente revisión literaria sobre el estado de conocimiento de las tortugas continentales de Colombia. La tasa de publicaciones sobre estas especies ha incrementado exponencialmente desde los años 1950s, aunque muchas de éstas no podrían haber sido detectadas usando búsquedas de literatura por internet. Los tópicos más comunes de las publicaciones fueron sistemática y filo-geografía, ecología de anidación, y manejo. En los años 1970s y 1980s, la tasa de publicaciones sobre temas de ecología y genética de poblaciones ocupando el territorio colombiano, estuvo por debajo de publicaciones sobre estos dos tópicos con poblaciones de las mismas especies en otras regiones de Suramérica. Sin embargo, actualmente la producción en ambas regiones es comparable. En otros países, detectamos una tendencia temporal significativa de publicar cada vez más en inglés y en revistas de mayor impacto; esta tendencia no fue significativa para las publicaciones sobre poblaciones de tortugas colombianas. En Colombia, un número desproporcionado de las publicaciones son sobre especies de tamaños grandes que enfrentan problemas de conservación. Argumentamos que estudios futuros de las especies de tortugas continentales de Colombia relativamente bien conocidas, se deberían enfocar en evaluar la efectividad de los programas de manejo, y también debemos dar prioridad a investigaciones que aumenten el estado de conocimiento de las especies de tortugas continentales poco estudiadas en el país, especialmente de aquellas que actualmente están categorizadas por la UICN como con datos deficientes (DD).The citations contained in a recent literature review on the freshwater turtle and tortoise species of Colombia were analyzed. Publishing rates on these species have been increasing exponentially since the 1950s, although many of the publications would not be detected using internet-based literature searches. The most common topics of publications were systematics and phylogeography, nesting ecology, and management. In the 1970s and 1980s, the rate of publishing on the ecology and genetics of Colombian populations lagged behind the rate of publishing on these topics for populations of Colombian freshwater turtle and tortoise species located in other countries, but currently the production of the two regions is comparable. Also, in other countries there were trends towards publishing more over time in English and in journals with higher impact factors, but these trends were not significant for publications on Colombian populations. In Colombia, a disproportionate number of studies have been published on large-bodied species that face conservation problems. We argue that future studies of already well-studied Colombian species should focus on evaluating the effectiveness of management programs, and priority also should be given to increasing our knowledge of the many poorly-studied species in the country, especially those currently classified by the IUCN as data deficient (DD)

A comprehensive study of GRB 070125, a most energetic gamma ray burst

We present a comprehensive multiwavelength analysis of the bright, long duration gamma-ray burst GRB 070125, comprised of observations in $\gamma$-ray, X-ray, optical, millimeter and centimeter wavebands. Simultaneous fits to the optical and X-ray light curves favor a break on day 3.78, which we interpret as the jet break from a collimated outflow. Independent fits to optical and X-ray bands give similar results in the optical bands but shift the jet break to around day 10 in the X-ray light curve. We show that for the physical parameters derived for GRB 070125, inverse Compton scattering effects are important throughout the afterglow evolution. While inverse Compton scattering does not affect radio and optical bands, it may be a promising candidate to delay the jet break in the X-ray band. Radio light curves show rapid flux variations, which are interpreted as due to interstellar scintillation, and are used to derive an upper limit of $2.4 \times 10^{17}$ cm on the radius of the fireball in the lateral expansion phase of the jet. Radio light curves and spectra suggest a high synchrotron self absorption frequency indicative of the afterglow shock wave moving in a dense medium. Our broadband modeling favors a constant density profile for the circumburst medium over a wind-like profile ($R^{-2}$). However, keeping in mind the uncertainty of the parameters, it is difficult to unambiguously distinguish between the two density profiles. Our broadband fits suggest that \event is a burst with high radiative efficiency ($> 60$).Comment: 50 pages, 33 figures, sty file included, Appeared in 20 Aug 2008 edition of Astrophysical Journa

IR Background Anisotropies in Spitzer GOODS images and constraints on first galaxies

We describe the angular power spectrum of unresolved 3.6 micron IR light in Spitzer GOODS fields. The amplitude of the anisotropy spectrum decreases with decreasing flux threshold to which resolved sources are removed from images. When all pixels brighter than a Vega magnitude of 24.6 are removed, the amplitude of the power spectrum at arcminute angular scales can be described with an extra component of z>8 sources with a IRB contribution around 0.4 nW m^-2 sr-1. The shape of the power spectrum, however, is more consistent with that expected for unresolved, faint galaxies at lower redshifts with Vega magnitudes fainter than 23 with a total 3.6 micron intensity between 0.1 to 0.8 nW m^-2 sr^-1. We confirm this assumption by showing that large-scale power decreases rapidly when the unresolved clustering spectrum is measured from a processed HDF-N IRAC image where locations of faint ACS sources with no IR counterparts were also masked. Based on resolved counts and unresolved fluctuations, we find that, at most, about 7.0 nW m^-2 sr^-1 can be ascribed to galaxies.Comment: 4 pages, 3 figures; for additional information see astro-ph/0609451 ; data products are available at http://www.cooray.org/spitzer.htm

HerMES: the rest-frame UV emission and a lensing model for the z= 6.34 luminous dusty starburst galaxy HFLS3

We discuss the rest-frame ultraviolet emission from the starbursting galaxy HFLS3 at a redshift of 6.34. The galaxy was discovered in Herschel/SPIRE data due to its red color in the submillimeter wavelengths from 250 to 500 μm. Keck/NIRC2 K s -band adaptive optics imaging data showed two potential near-IR counterparts near HFLS3. Previously, the northern galaxy was taken to be in the foreground at z = 2.1, while the southern galaxy was assumed to be HFLS3's near-IR counterpart. The recently acquired Hubble/WFC3 and Advanced Camera for Surveys (ACS) imaging data show conclusively that both optically bright galaxies are in the foreground at z < 6. A new lensing model based on the Hubble imaging data and the millimeter-wave continuum emission yields a magnification factor of 2.2 ± 0.3, with a 95% confidence upper limit on the magnification of 3.5. When corrected for lensing, the instantaneous star formation rate is 1320 M ☉ yr–1, with the 95% confidence lower limit around 830 M ☉ yr–1. The dust and stellar masses of HFLS3 from the same spectral energy distribution (SED) models are at the level of 3 × 108 M ☉ and ~5 × 1010 M ☉, respectively, with large systematic uncertainties on assumptions related to the SED model. With Hubble/WFC3 images, we also find diffuse near-IR emission about 0.5 arcsec (~3 kpc) to the southwest of HFLS3 that remains undetected in the ACS imaging data. The emission has a photometric redshift consistent with either z ~ 6 or a dusty galaxy template at z ~ 2

CMB polarimetry with BICEP: instrument characterization, calibration, and performance

BICEP is a ground-based millimeter-wave bolometric array designed to target the primordial gravity wave signature on the polarization of the cosmic microwave background (CMB) at degree angular scales. Currently in its third year of operation at the South Pole, BICEP is measuring the CMB polarization with unprecedented sensitivity at 100 and 150 GHz in the cleanest available 2% of the sky, as well as deriving independent constraints on the diffuse polarized foregrounds with select observations on and off the Galactic plane. Instrument calibrations are discussed in the context of rigorous control of systematic errors, and the performance during the first two years of the experiment is reviewed.Comment: 12 pages, 15 figures, updated version of a paper accepted for Millimeter and Submillimeter Detectors and Instrumentation for Astronomy IV, Proceedings of SPIE, 7020, 200

Absolute polarization angle calibration using polarized diffuse Galactic emission observed by BICEP

We present a method of cross-calibrating the polarization angle of a polarimeter using BICEP Galactic observations. \bicep\ was a ground based experiment using an array of 49 pairs of polarization sensitive bolometers observing from the geographic South Pole at 100 and 150 GHz. The BICEP polarimeter is calibrated to +/-0.01 in cross-polarization and less than +/-0.7 degrees in absolute polarization orientation. BICEP observed the temperature and polarization of the Galactic plane (R.A= 100 degrees ~ 270 degrees and Dec. = -67 degrees ~ -48 degrees). We show that the statistical error in the 100 GHz BICEP Galaxy map can constrain the polarization angle offset of WMAP Wband to 0.6 degrees +\- 1.4 degrees. The expected 1 sigma errors on the polarization angle cross-calibration for Planck or EPIC are 1.3 degrees and 0.3 degrees at 100 and 150 GHz, respectively. We also discuss the expected improvement of the BICEP Galactic field observations with forthcoming BICEP2 and Keck observations.Comment: 13 pages, 10 figures and 2 tables. To appear in Proceedings of SPIE Astronomical Telescopes and Instrumentation 201

A Comprehensive Study of GRB 070125, A Most Energetic Gamma-Ray Burst

We present a comprehensive multiwavelength analysis of the bright, long-duration gamma-ray burst GRB 070125, comprised of observations in gamma-ray, X-ray, optical, millimeter, and centimeter wave bands. Simultaneous fits to the optical and X-ray light curves favor a break on day 3.78, which we interpret as the jet break from a collimated outflow. Independent fits to optical and X-ray bands give similar results in the optical bands but shift the jet break to around day 10 in the X-ray light curve. We show that for the physical parameters derived for GRB 070125, inverse Compton scattering effects are important throughout the afterglow evolution. While inverse Compton scattering does not affect radio and optical bands, it may be a promising candidate to delay the jet break in the X-ray band. Radio light curves show rapid flux variations, which are interpreted as due to interstellar scintillation and used to derive an upper limit of 2.4 × 10 17 cm on the radius of the fireball in the lateral expansion phase of the jet. Radio light curves and spectra suggest a high synchrotron self-absorption frequency indicative of the afterglow shock wave moving in a dense medium. Our broadband modeling favors a constant density profile for the circumburst medium over a windlike profile (R -2). However, keeping in mind the uncertainty of the parameters, it is difficult to unambiguously distinguish between the two density profiles. Our broadband fits suggest that GRB 070125 is a burst with high radiative efficiency (>60%).R. A. C. was supported in part by NASA grant NNG06GJ33G

Refractory testicular germ cell tumors are highly sensitive to the second generation DNA methylation inhibitor guadecitabine

Testicular germ cell tumors (TGCTs) are the most common cancers of young males. A substantial portion of TGCT patients are refractory to cisplatin. There are no effective therapies for these patients, many of whom die from progressive disease. Embryonal carcinoma (EC) are the stem cells of TGCTs. In prior in vitro studies we found that EC cells were highly sensitive to the DNA methyltransferase inhibitor, 5-aza deoxycytidine (5-aza). Here, as an initial step in bringing demethylation therapy to the clinic for TGCT patients, we evaluated the effects of the clinically optimized, second generation demethylating agent guadecitabine (SGI-110) on EC cells in an animal model of cisplatin refractory testicular cancer. EC cells were exquisitely sensitive to guadecitabine and the hypersensitivity was dependent on high levels of DNA methyltransferase 3B. Guadecitabine mediated transcriptional reprogramming of EC cells included induction of p53 targets and repression of pluripotency genes. As a single agent, guadecitabine completely abolished progression and induced complete regression of cisplatin resistant EC xenografts even at doses well below those required to impact somatic solid tumors. Low dose guadecitabine also sensitized refractory EC cells to cisplatin in vivo. Genome-wide analysis indicated that in vivo antitumor activity was associated with activation of p53 and immune-related pathways and the antitumor effects of guadecitabine were dependent on p53, a gene rarely mutated in TGCTs. These preclinical findings suggest that guadecitabine alone or in combination with cisplatin is a promising strategy to treat refractory TGCT patients