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 & Aerosol. The organization has 8749 authors who have published 20843 publications receiving 795706 citations. The organization is also known as: UMBC.

Nitrogen Fluxes and Retention in Urban Watershed Ecosystems

Abstract: Although the watershed approach has long been used to study whole-ecosystem function, it has seldom been applied to study human-dominated systems, especially those dominated by urban and suburban land uses. Here we present 3 years of data on nitrogen (N) losses from one completely forested, one agricultural, and six urban/suburban watersheds, and input– output N budgets for suburban, forested, and agricultural watersheds. The work is a product of the Baltimore Ecosystem Study, a longterm study of urban and suburban ecosystems, and a component of the US National Science Foundation’s long-term ecological research (LTER) network. As expected, urban and suburban watersheds had much higher N losses than did the completely forested watershed, with N yields ranging from 2.9 to 7.9 kg N ha 1 y 1 in the urban and suburban watersheds compared with less than 1 kg N ha 1 y 1 in the completely forested watershed. Yields from urban and suburban watersheds were lower than those from an agricultural watershed (13–19.8 kg Nh a 1 y 1 ). Retention of N in the suburban watershed was surprisingly high, 75% of inputs, which were dominated by home lawn fertilizer (14.4 kg N ha 1 y 1 ) and atmospheric deposition (11.2 kg N ha 1 y 1 ). Detailed analysis of mechanisms of N retention, which must occur in the significant amounts of pervious surface present in urban and suburban watersheds, and which include storage in soils and vegetation and gaseous loss, is clearly warranted.

Fault-tolerant clustering of wireless sensor networks

Abstract: During the past few years distributed wireless sensor networks have been the focus of considerable research for both military and civil applications. Sensors are generally constrained in on-board energy supply therefore efficient management of the network is crucial to extend the life of the system. Sensors' energy cannot support long haul communication to reach a remote command site, thus they require multi-tier architecture to forward data. An efficient way to enhance the lifetime of the system is to partition the network into distinct clusters with a high-energy node called a gateway as cluster-head. Failures are inevitable in sensor networks due to the inhospitable environment and unattended deployment. However, failures in higher level of hierarchy e.g. cluster-head cause more damage to the system because they also limit accessibility to the nodes that are under their supervision. In this paper we propose an efficient mechanism to recover sensors from a failed cluster. Our approach avoids a full-scale re-clustering and does not require deployment of redundant gateways.

Structure of the Amino-Terminal Core Domain of the HIV-1 Capsid Protein

Abstract: The three-dimensional structure of the amino-terminal core domain (residues 1 through 151) of the human immunodeficiency virus-type 1 (HIV-1) capsid protein has been solved by multidimensional heteronuclear magnetic resonance spectroscopy. The structure is unlike those of previously characterized viral coat proteins and is composed of seven alpha helices, two beta hairpins, and an exposed partially ordered loop. The domain is shaped like an arrowhead, with the beta hairpins and loop exposed at the trailing edge and the carboxyl-terminal helix projecting from the tip. The proline residue Pro1 forms a salt bridge with a conserved, buried aspartate residue (Asp51), which suggests that the amino terminus of the protein rearranges upon proteolytic maturation. The binding site for cyclophilin A, a cellular rotamase that is packaged into the HIV-1 virion, is located on the exposed loop and encompasses the essential proline residue Pro90. In the free monomeric domain, Pro90 adopts kinetically trapped cis and trans conformations, raising the possibility that cyclophilin A catalyzes interconversion of the cis- and trans-Pro90 loop structures.

MODIS Collection 6 MAIAC Algorithm

Abstract: . This paper describes the latest version of the algorithm MAIAC used for processing the MODIS Collection 6 data record. Since initial publication in 2011–2012, MAIAC has changed considerably to adapt to global processing and improve cloud/snow detection, aerosol retrievals and atmospheric correction of MODIS data. The main changes include (1) transition from a 25 to 1 km scale for retrieval of the spectral regression coefficient (SRC) which helped to remove occasional blockiness at 25 km scale in the aerosol optical depth (AOD) and in the surface reflectance, (2) continuous improvements of cloud detection, (3) introduction of smoke and dust tests to discriminate absorbing fine- and coarse-mode aerosols, (4) adding over-water processing, (5) general optimization of the LUT-based radiative transfer for the global processing, and others. MAIAC provides an interdisciplinary suite of atmospheric and land products, including cloud mask (CM), column water vapor (CWV), AOD at 0.47 and 0.55 µ m, aerosol type (background, smoke or dust) and fine-mode fraction over water; spectral bidirectional reflectance factors (BRF), parameters of Ross-thick Li-sparse (RTLS) bidirectional reflectance distribution function (BRDF) model and instantaneous albedo. For snow-covered surfaces, we provide subpixel snow fraction and snow grain size. All products come in standard HDF4 format at 1 km resolution, except for BRF, which is also provided at 500 m resolution on a sinusoidal grid adopted by the MODIS Land team. All products are provided on per-observation basis in daily files except for the BRDF/Albedo product, which is reported every 8 days. Because MAIAC uses a time series approach, BRDF/Albedo is naturally gap-filled over land where missing values are filled-in with results from the previous retrieval. While the BRDF model is reported for MODIS Land bands 1–7 and ocean band 8, BRF is reported for both land and ocean bands 1–12. This paper focuses on MAIAC cloud detection, aerosol retrievals and atmospheric correction and describes MCD19 data products and quality assurance (QA) flags.

Maternal Depression and the Quality of Early Attachment: An Examination of Infants, Preschoolers, and Their Mothers.

Abstract: Relations between maternal depression and attachment security among 50 infant-mother and 54 preschool child-mother dyads were examined using the classification system of M.D.S. Ainsworth, M.C. Blehar, E. Waters, and S. Wall (1979) and M. Main and J. Solomon (1990) for infants and the Preschool Assessment (P.M. Crittenden, 1992b) for preschoolers. Attachment insecurity was significantly associated with maternal depression among infants and preschoolers. Futhermore, children without unitary, coherent attachment strategies tended to have more chronically impaired mothers than did children with coherent, organzed attachment strategies. Results stress the importance of severity-chronicity of parental illness in the study of depression and early attachment relations, and that differences between children with and without coherent, organized attachment strategies are as clinically informative as are differences between secure and insecure children