The University of Maryland University College is an American public university located in the unincorporated community of Adelphi in Prince George's County, Maryland in the United States. It is known primarily for its distance learning classes and programs, but UMUC also offers classes on campus at its Academic Center in Largo, and at satellite campuses across the Baltimore-Washington Metropolitan Area, throughout Maryland, as well as in Europe, the Middle East, and Asia. UMUC serves over 90,000 students worldwide and is one of the largest distance learning institutions in the world. UMUC is open to all applicants with a 100 percent acceptance rate for undergraduate programs. The university offers 120 academic programs in instructor-led and online classes, including bachelor, masters, and doctoral degrees as well as undergraduate and graduate certificates. UMUC is a member of the University System of Maryland, which includes eleven separate public universities in Maryland. Wikipedia.
University of Maryland University College, United States Of America, George Mason University and George Washington University | Date: 2016-10-19
A nanostructure sensing device comprises a semiconductor nanostructure having an outer surface, and at least one of metal or metal-oxide nanoparticle clusters functionalizing the outer surface of the nanostructure and forming a photoconductive nanostructure/nanocluster hybrid sensor enabling light-assisted sensing of a target analyte.
The United States Of America and University of Maryland University College | Date: 2015-04-17
An approach is presented to recontruct image data for an object using a partial set of magnetic resonance (MR) measurements. A subset of data points in a data space representing an object are selected (e.g. through random sampling) for MR data acquisition. Partial MR data corresponding to the subset of data points is received and used for image reconstruction. The overall speed of image reconstruction can be reduced dramatically by relying on acquisition of data for the subset of data points rather than for all data points in the data space representing the object. Compressive sensing type arguments are used to fill in missing measurements, using a priori knowledge of the structure of the data. A compressed data matrix can be recovered from measurements that form a tight frame. It can be established that these measurements satisfy the restricted isometry property (RIP). The zeroth-order regularization minimization problem can then be solved, for example, using a 2D ILT approach.
Cooper E.D.,University of Maryland University College
Trends in Plant Science | Year: 2014
Phylogenetic analysis is an increasingly common and valuable component of plant science. Knowledge of the phylogenetic relationships between plant groups is a prerequisite for understanding the origin and evolution of important plant features, and phylogenetic analysis of individual genes and gene families provides fundamental insights into how those genes and their functions evolved. However, despite an active research community exploring and improving phylogenetic methods, the analytical methods commonly used, and the phylogenetic results they produce, are accorded far more confidence than they warrant. In this opinion article, I emphasise that important parts of the green plant phylogeny are inconsistently resolved and I argue that the lack of consistency arises due to inadequate modelling of changes in the substitution process. © 2014 Elsevier Ltd.
A'Hearn M.F.,University of Maryland University College
Annual Review of Astronomy and Astrophysics | Year: 2011
Recent results, many but not all from flybys of comets by spacecraft, particularly the results from Deep Impact, have dramatically improved our understanding of the physical properties of cometary nuclei. Characteristic features are modest size (R<20 km), high porosity, low strength, and heterogeneity. There is also evidence that can be interpreted as showing the original cometesimals in a cometary nucleus and suggesting radial migration of macroscopic cometesimals during the aggregation of nuclei, which in turn aggregated into the cores of the giant planets. © 2011 by Annual Reviews. All rights reserved.
Levin M.,University of Maryland University College
Physical Review X | Year: 2013
We discuss the question of when a gapped two-dimensional electron system without any symmetry has a protected gapless edge mode. While it is well known that systems with a nonzero thermal Hall conductance, KH ≠ 0, support such modes, here we show that robust modes can also occur when KH = 0-if the system has quasiparticles with fractional statistics. We show that some types of fractional statistics are compatible with a gapped edge, while others are fundamentally incompatible. More generally, we give a criterion for when an electron system with Abelian statistics and KH = 0 can support a gapped edge: We show that a gapped edge is possible if and only if there exists a subset of quasiparticle typesMsuch that (1) all the quasiparticles inMhave trivial mutual statistics, and (2) every quasiparticle that is not in M has nontrivial mutual statistics with at least one quasiparticle in M. We derive this criterion using three different approaches: a microscopic analysis of the edge, a general argument based on braiding statistics, and finally a conformal field theory approach that uses constraints from modular invariance. We also discuss the analogous result for two-dimensional boson systems. © Published by the American Physical Society.
Isaacs L.,University of Maryland University College
Accounts of Chemical Research | Year: 2014
ConspectusThis Account focuses on stimuli responsive systems that function in aqueous solution using examples drawn from the work of the Isaacs group using cucurbit[n]uril (CB[n]) molecular containers as key recognition elements. Our entry into the area of stimuli responsive systems began with the preparation of glycoluril derived molecular clips that efficiently distinguish between self and nonself by H-bonds and π-π interactions even within complex mixtures and therefore undergo self-sorting. We concluded that the selectivity of a wide variety of H-bonded supramolecular assemblies was higher than previously appreciated and that self-sorting is not exceptional behavior. This lead us to examine self-sorting within the context of CB[n] host-guest chemistry in water.We discovered that CB[n] homologues (CB and CB) display remarkably high binding affinity (Ka up to 1017 M-1) and selectivity toward their guests, which renders CB[n]s prime components for the construction of stimuli responsive host-guest systems. The CB ·adamantaneammonium ion complex, which is particularly privileged (K a = 4.2 × 1012 M-1), was introduced by us as a stimulus to trigger constitutional changes in multicomponent self-sorting systems. For example, we describe how the free energy associated with the formation of host-guest complexes of CB[n]-type receptors can drive conformational changes of included guests like triazene-arylene foldamers and cationic calixarenes, as well as induced conformational changes (e.g., ammonium guest size dependent homotropic allostery, metal ion triggered folding, and heterochiral dimerization) of the hosts themselves.Many guests display large pKa shifts within their CB[n]-guest complexes, which we used to promote pH controlled guest swapping and thermal trans-to-cis isomerization of azobenzene derivatives. We also used the high affinity and selectivity of CB toward its guests to outcompete an enzyme (bovine carbonic anhydrase) for a two-faced inhibitor, which allowed stimuli responsive regulation of enzymatic activity. These results prompted us to examine the use of CB[n]-type receptors in both in vitro and in vivo biological systems. We demonstrated that adamantaneammonium ion can be used to intracellularly sequester CB from gold nanoparticles passivated with hexanediammonium ion·CB complexes and thereby trigger cytotoxicity. CB derivatives bearing a biotin targeting group enhance the cytotoxicity of encapsulated oxaliplatin toward L1210FR cells. Finally, acyclic CB[n]-type receptors function as solubilizing excipients for insoluble drugs for drug delivery purposes and as a broad spectrum reversal agent for the neuromuscular blocking agents rocuronium, vecuronium, and cis-atracurium in rats. The work highlights the great potential for integration of CB[n]-type receptors with biological systems. © 2014 American Chemical Society.
Nagarajan N.,Genome Institute of Singapore |
Pop M.,University of Maryland University College
Nature Reviews Genetics | Year: 2013
Advances in sequencing technologies and increased access to sequencing services have led to renewed interest in sequence and genome assembly. Concurrently, new applications for sequencing have emerged, including gene expression analysis, discovery of genomic variants and metagenomics, and each of these has different needs and challenges in terms of assembly. We survey the theoretical foundations that underlie modern assembly and highlight the options and practical trade-offs that need to be considered, focusing on how individual features address the needs of specific applications. We also review key software and the interplay between experimental design and efficacy of assembly. © 2013 Macmillan Publishers Limited. All rights reserved.
Cohen H.B.,University of Maryland University College
Blood | Year: 2013
Sepsis is a highly fatal disease caused by an initial hyperinflammatory response followed by a state of profound immunosuppression. Although it is well appreciated that the initial production of proinflammatory cytokines by macrophages accompanies the onset of sepsis, it remains unclear what causes the transition to an immunosuppressive state. In this study, we reveal that macrophages themselves are key regulators of this transition and that the surface enzyme CD39 plays a critical role in self-limiting the activation process. We demonstrate that Toll-like receptor (TLR)-stimulated macrophages modulate their activation state by increasing the synthesis and secretion of adenosine triphosphate (ATP). This endogenous ATP is paradoxically immunosuppressive due to its rapid catabolism into adenosine by CD39. Macrophages lacking CD39 are unable to transition to a regulatory state and consequently continue to produce inflammatory cytokines. The importance of this transition is demonstrated in a mouse model of sepsis, where small numbers of CD39-deficient macrophages were sufficient to induce lethal endotoxic shock. Thus, these data implicate CD39 as a key "molecular switch" that allows macrophages to self-limit their activation state. We propose that therapeutics targeting the release and hydrolysis of ATP by macrophages may represent new ways to treat inflammatory diseases.
Vedernikov A.N.,University of Maryland University College
Accounts of Chemical Research | Year: 2012
A tom economy and the use of "green" reagents in organic oxidation, including oxidation of hydrocarbons, remain challenges for organic synthesis. Solutions to this problem would lead to a more sustainable economy because of improved access to energy resources such as natural gas. Although natural gas is still abundant, about a third of methane extracted in distant oil fields currently cannot be used as a chemical feedstock because of a dearth of economically and ecologically viable methodologies for partial methane oxidation. Two readily available "atom-economical" "green" oxidants are dioxygen and hydrogen peroxide, but few methodologies have utilized these oxidants effectively in selective organic transformations. Hydrocarbon oxidation and C-H functionalization reactions rely on Pd II and Pt II complexes. These reagents have practical advantages because they can toleratemoisture and atmospheric oxygen. But this tolerance for atmospheric oxygen also makes it challenging to develop novel organometallic palladium and platinumcatalyzed C-H oxidation reactions utilizing O 2 or H 2O 2. This Account focuses on these challenges: the development of M-C bond (M = Pt II, Pd II) functionalization and related selective hydrocarbon C-H oxidations with O 2 or H 2O 2. Reactions discussed in this Account do not involve mediators, since the latter can impart low reaction selectivity and catalyst instability. As an efficient solution to the problem of directM-C oxidation and functionalization with O 2 and H 2O 2, this Account introduces the use of facially chelating semilabile ligands such as di(2-pyridyl)methanesulfonate and the hydrated form of di(2-pyridyl)ketone that enable selective and facile M II-C(sp n) bond functionalization with O 2 (M = Pt, n = 3; M = Pd, n =3(benzylic)) or H 2O 2 (M = Pd,n = 2). The reactions proceed efficiently in protic solvents such as water, methanol, or acetic acid. With the exception of benzylic Pd II complexes, the organometallic substrates studied form isolable high-valent Pt IV or Pd IV intermediates as a result of an oxidant attack at theM II atom. The resulting high-valentM IV intermediates undergo C-O reductive elimination, leading to products in high yields. Guidelines for the synthesis of products containing other Pd III bonds (X = OAc, Cl, Br) while using O 2 or H 2O 2 as oxidants are also discussed. Although the M II-C bond functionalization reactions including high-valent intermediates are well understood, the mechanism for the aerobic functionalization of benzylic Pd II complexes will require a more detailed exploration. Importantly, further optimization of the systems suitable for stoichiometric M II-C bond functionalization led to the development of catalytic reactions, including selective acetoxylation of benzylic C-H bonds with O 2 as the oxidant and hydroxylation of aromatic C-H bonds with H 2O 2 in acetic acid solutions. Both reactions proceed efficiently with substrates that contain a directing heteroatom. This Account also describes catalytic methods for ethylene dioxygenation with H 2O 2 using M II complexes supported by facially chelating ligands. Mechanistic studies of these new oxidation reactions point to important ways to improve their substrate scope and to develop "green" CH functionalization chemistry. © 2011 American Chemical Society.
Via S.,University of Maryland University College
Philosophical Transactions of the Royal Society B: Biological Sciences | Year: 2012
In allopatric populations, geographical separation simultaneously isolates the entire genome, allowing genetic divergence to accumulate virtually anywhere in the genome. In sympatric populations, however, the strong divergent selection required to overcome migration produces a genetic mosaic of divergent and non-divergent genomic regions. In some recent genome scans, each divergent genomic region has been interpreted as an independent incidence of migration/selection balance, such that the reduction of gene exchange is restricted to a few kilo bases around each divergently selected gene. I propose an alternative mechanism, 'divergence hitchhiking' (DH), in which divergent selection can reduce gene exchange for several mega bases around a gene under strong divergent selection. Not all genes/markers within a DH region are divergently selected, yet the entire region is protected to some degree from gene exchange, permitting genetic divergence from mechanisms other than divergent selection to accumulate secondarily. After contrasting DH and multilocus migration/ selection balance (MM/SB), I outline a model in which genomic isolation at a given genomic location is jointly determined by DH and genome-wide effects of the progressive reduction in realized migration, then illustrate DH using data from several pairs of incipient species in the wild. © 2011 The Royal Society.