University of Maryland, Baltimore County

About: University of Maryland, Baltimore County is a education organization based out in Baltimore, Maryland, United States. It is known for research contribution in the topics: Population & Galaxy. The organization has 8749 authors who have published 20843 publications receiving 795706 citations. The organization is also known as: UMBC.

Fermi Observations of High-Energy Gamma-Ray Emission from GRB 080916C

Abstract: Gamma-ray bursts (GRBs) are highly energetic explosions signaling the death of massive stars in distant galaxies. The Gamma-ray Burst Monitor and Large Area Telescope onboard the Fermi Observatory together record GRBs over a broad energy range spanning about 7 decades of gamma-ray energy. In September 2008, Fermi observed the exceptionally luminous GRB 080916C, with the largest apparent energy release yet measured. The high-energy gamma rays are observed to start later and persist longer than the lower energy photons. A simple spectral form fits the entire GRB spectrum, providing strong constraints on emission models. The known distance of the burst enables placing lower limits on the bulk Lorentz factor of the outflow and on the quantum gravity mass.

The versatile epsilon-proteobacteria: key players in sulphidic habitats.

Abstract: The epsilon-proteobacteria have recently been recognized as globally ubiquitous in modern marine and terrestrial ecosystems, and have had a significant role in biogeochemical and geological processes throughout Earth's history. To place this newly expanded group, which consists mainly of uncultured representatives, in an evolutionary context, we present an overview of the taxonomic classification for the class, review ecological and metabolic data in key sulphidic habitats and consider the ecological and geological potential of the epsilon-proteobacteria in modern and ancient systems. These integrated perspectives provide a framework for future culture- and genomic-based studies.

Advancing E-Government at the Grassroots: Tortoise or Hare?

Abstract: American grassroots governments have rushed to join the e-government revolution. Although there is a growing body of e-government literature, little of it is empirical. Using data from two nationwide surveys, we conduct a longitudinal examination of local government adoption of e-government, Web site sophistication, the perceived impacts of e-government, and barriers to the adoption and sophistication of e-government. We also discuss correlates of e-government adoption and sophistication with selected institutional factors. We find that e-government adoption at the grassroots is progressing rapidly (if measured solely by deployment of Web sites). However, the movement toward integrated and transactional e-government is progressing much more slowly. Continuing research, particularly longitudinal study, is needed to monitor the evolution of e-government among U.S. local governments, especially to keep pace with the practice and to ascertain the actual impacts of e-government.

Two-photon imaging with thermal light.

Abstract: We report the first experimental demonstration of two-photon imaging with a pseudothermal source. Similarly to the case of entangled states, a two-photon Gaussian thin lens equation is observed, indicating EPR type correlation in position. We introduce the concepts of two-photon coherent and two-photon incoherent imaging. The differences between the entangled and the thermal cases are explained in terms of these concepts.

Structure of the HIV-1 Nucleocapsid Protein Bound to the SL3 Ψ-RNA Recognition Element

Abstract: The three-dimensional structure of the human immunodeficiency virus–type 1 (HIV-1) nucleocapsid protein (NC) bound to the SL3 stem-loop recognition element of the genomic Ψ RNA packaging signal has been determined by heteronuclear magnetic resonance spectroscopy. Tight binding (dissociation constant, ∼100 nM) is mediated by specific interactions between the amino- and carboxyl-terminal CCHC-type zinc knuckles of the NC protein and the G7 and G9 nucleotide bases, respectively, of the G6-G7-A8-G9 RNA tetraloop. A8 packs against the amino-terminal knuckle and forms a hydrogen bond with conserved Arg32, and residues Lys3 to Arg10 of NC form a 310helix that binds to the major groove of the RNA stem and also packs against the amino-terminal zinc knuckle. The structure provides insights into the mechanism of viral genome recognition, explains extensive amino acid conservation within NC, and serves as a basis for the development of inhibitors designed to interfere with genome encapsidation.