Determination of atmospheric Hg by collection on iodated carbon,acid digestion and CVAFS detection     

Nicolas S. Bloom  Eric M. Prestbo  Björn Hall  Eric J. Von Der Geest 《Water, air, and soil pollution》1995,80(1-4):1315-1318

An established industrial monitoring technique has been refined to allow the accurate determination of total gaseous Hg in air at background levels (1–3 ng·m^?3). Samples are collected under vacuum through a commercially available iodide-impregnated carbon trap. For analysis, the trap is digested in a 7∶3 (v/v) mixture of HNO₃+H₂SO₄, and an aliquot of the digest analyzed by SnCl₂ reduction, dual gold amalgamation, and cold vapor atomic fluorescence spectrometric (CVAFS) detection. The traps exhibit little breakthrough (<5%) under flow rates of up to 1.0 l·min^?1 for periods up to 10 days. The mean value for the blank on the half traps was found to be 0.40±0.16 ng (n=20), resulting in a 3 α detection limit of 0.07 ng·m (1 week sample at 1.0 L·m^?3). Replicate field collections show a between-trap RSD of ± 6.4%, while field intercomparison with gold trapping resulted in 104±20% recovery in the 1–4 ng/m³ concentration range.  相似文献   

An open letter to Elias Zerhouni     

Altman S  Bassler BL  Beckwith J  Belfort M  Berg HC  Bloom B  Brenchley JE  Campbell A  Collier RJ  Connell N  Cozzarelli NR  Craig NL  Darst S  Ebright RH  Elledge SJ  Falkow S  Galan JE  Gottesman M  Gourse R  Grindley ND  Gross CA  Grossman A  Hochschild A  Howe M  Hurwitz J  Isberg RR  Kaplan S  Kornberg A  Kustu SG  Landick RC  Landy A  Levy SB  Losick R  Long SR  Maloy SR  Mekalanos JJ  Neidhardt FC  Pace NR  Ptashne M  Roberts JW  Roth JR  Rothman-Denes LB  Salyers A  Schaechter M  Shapiro L  Silhavy TJ  Simon MI  Walker G 《Science (New York, N.Y.)》2005,307(5714):1409-1410

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Electron-microscopic autoradiography of rat hypothalamus after intraventricular h3-norepinephrine     

Aghajanian GK  Bloom FE 《Science (New York, N.Y.)》1966,153(3733):308-310

Tritiated norepinephrine was injected into the lateral ventricles of rats, and its localization in the hypothalamus was determined by light and electron-microscopic autoradiography. Eighty percent of the autoradiographic grains were located over nerve endings and unmyelinated axons. Large, dense synaptic vesicles were present in most of the endings and axons with activity. Grains were rarely seen over myelinated axons, glia, or blood vessels.  相似文献   

7 billion and counting   总被引：1，自引：0，他引：1  

Bloom DE 《Science (New York, N.Y.)》2011,333(6042):562-569

The world is currently in the midst of the greatest demographic upheaval in human history. Dramatic reductions in mortality, followed (but with a lag) by equally marked reductions in fertility, resulted in a doubling of world population between 1960 and 2000. A further increase of 2 to 4.5 billion is projected for the current half-century, with the increase concentrated in the world's least developed countries. Despite alarmist predictions, historical increases in population have not been economically catastrophic. Moreover, changes in population age structure have opened the door to increased prosperity. Demographic changes have had and will continue to have profound repercussions for human well-being and progress, with some possibilities for mediating those repercussions through policy intervention.  相似文献   

Urbanization and the wealth of nations   总被引：3，自引：0，他引：3  

Bloom DE  Canning D  Fink G 《Science (New York, N.Y.)》2008,319(5864):772-775

The proportion of a country's population living in urban areas is highly correlated with its level of income. Urban areas offer economies of scale and richer market structures, and there is strong evidence that workers in urban areas are individually more productive, and earn more, than rural workers. However, rapid urbanization is also associated with crowding, environmental degradation, and other impediments to productivity. Overall, we find no evidence that the level of urbanization affects the rate of economic growth. Our findings weaken the rationale for either encouraging or discouraging urbanization as part of a strategy for economic growth.  相似文献   

Circumstellar material in type Ia supernovae via sodium absorption features     

Sternberg A  Gal-Yam A  Simon JD  Leonard DC  Quimby RM  Phillips MM  Morrell N  Thompson IB  Ivans I  Marshall JL  Filippenko AV  Marcy GW  Bloom JS  Patat F  Foley RJ  Yong D  Penprase BE  Beeler DJ  Allende Prieto C  Stringfellow GS 《Science (New York, N.Y.)》2011,333(6044):856-859

Type Ia supernovae are key tools for measuring distances on a cosmic scale. They are generally thought to be the thermonuclear explosion of an accreting white dwarf in a close binary system. The nature of the mass donor is still uncertain. In the single-degenerate model it is a main-sequence star or an evolved star, whereas in the double-degenerate model it is another white dwarf. We show that the velocity structure of absorbing material along the line of sight to 35 type Ia supernovae tends to be blueshifted. These structures are likely signatures of gas outflows from the supernova progenitor systems. Thus, many type Ia supernovae in nearby spiral galaxies may originate in single-degenerate systems.  相似文献   

A cocoon of freshly accelerated cosmic rays detected by Fermi in the Cygnus superbubble     

Ackermann M  Ajello M  Allafort A  Baldini L  Ballet J  Barbiellini G  Bastieri D  Belfiore A  Bellazzini R  Berenji B  Blandford RD  Bloom ED  Bonamente E  Borgland AW  Bottacini E  Brigida M  Bruel P  Buehler R  Buson S  Caliandro GA  Cameron RA  Caraveo PA  Casandjian JM  Cecchi C  Chekhtman A  Cheung CC  Chiang J  Ciprini S  Claus R  Cohen-Tanugi J  de Angelis A  de Palma F  Dermer CD  do Couto E Silva E  Drell PS  Dumora D  Favuzzi C  Fegan SJ  Focke WB  Fortin P  Fukazawa Y  Fusco P  Gargano F  Germani S  Giglietto N  Giordano F 《Science (New York, N.Y.)》2011,334(6059):1103-1107

The origin of Galactic cosmic rays is a century-long puzzle. Indirect evidence points to their acceleration by supernova shockwaves, but we know little of their escape from the shock and their evolution through the turbulent medium surrounding massive stars. Gamma rays can probe their spreading through the ambient gas and radiation fields. The Fermi Large Area Telescope (LAT) has observed the star-forming region of Cygnus X. The 1- to 100-gigaelectronvolt images reveal a 50-parsec-wide cocoon of freshly accelerated cosmic rays that flood the cavities carved by the stellar winds and ionization fronts from young stellar clusters. It provides an example to study the youth of cosmic rays in a superbubble environment before they merge into the older Galactic population.  相似文献   

ON THE VITAMIN Bc CONJUGATE IN YEAST     

Binkley SB  Bird OD  Bloom ES  Brown RA  Calkins DG  Campbell CJ  Emmett AD  Pfiffner JJ 《Science (New York, N.Y.)》1944,100(2585):36-37

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ISOLATION OF AN ANTIANEMIA FACTOR (VITAMIN Bc CONJUGATE) IN CRYSTALLINE FORM FROM YEAST     

Pfiffner JJ  Calkins DG  O'dell BL  Bloom ES  Brown RA  Campbell CJ  Bird OD 《Science (New York, N.Y.)》1945,102(2644):228-230

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Immunoglobulin production by human lymphocytoid lines and clones: absence of genic exclusion   总被引：5，自引：0，他引：5  

A D Bloom  K W Choi  B J Lamb 《Science (New York, N.Y.)》1971,172(981):382-383

Immunoglobulin production was studied in established lines of normal human lymphocytes. Three lines which produced both immunoglobulin G and immunoglobulin M were cloned. Among the 25 immunoglobulin-producing clones, 23 produced both classes of immunoglobulins. These findings suggest that the phenomenon of genic exclusion does not hold for immunoglobulin production in lymphocytoid cells in culture.  相似文献