A Visualization of the Internet

Recent advances in event-driven information and real-time configurations have paved the way for evolutionary programming. In fact, few system administrators would disagree with the robust unification of 802.11 mesh networks and write-ahead logging, which embodies the appropriate principles of hardware and architecture. In this paper we introduce an analysis of the UNIVAC computer (YUX), arguing that Lamport clocks and DHCP are rarely incompatible

Phase noise in low-power radio communications

Thesis (Elec. E.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1996.Includes bibliographical references (leaves 99-101).by Donald C. Wilcoxson.Elec.E

Comparison of fish assemblages in two littoral habitats in a Neotropical morichal stream in Venezuela

Morichales are lowland streams in South American savannas with riparian forest dominated by the moriche palm (Mauritia flexuosa). We sampled littoral habitats from ten flooded vegetated patches (dominated by Mauritiella aculeate) and six sand banks in two months of the dry season (Feb-Mar 2005) in a stream in the savannas of Apure State, Venezuela. We collected samples that compromised 12,407 individual fishes of 107 species. Small-bodied fishes (\u3c 100 mm), representing diverse trophic and life history strategies, were abundant. The most abundant species were in the families Characidae and Cichlidae. Fish assemblages from flooded vegetated patches differed significantly from those on adjacent sand banks. High structural complexity along vegetated shoreline habitats of morichal streams likely contributes to species richness and affects assemblage composition

Novel one-dimensional structures and solution behaviour of copper(II) bromide and chloride complexes of a new pentapyridyldiamine ligand

Copper(II) bromide and chloride complexes of the new heptadentate ligand 2,6-bis(bis(2-pyridylmethyl)amino)methylpyridine (L) have been prepared. For the bromide complexes, chains of novel, approximately C-2-symmetric, chiral [Cu-2(L)Br-2](2+) 'wedge-shaped' tectons are found. The links between the dicopper tectons and the overall chirality and packing of the chains are dictated by the bromide ion content, not the counter anion. In contrast, the chloride complexes exhibit linked asymmetric [Cu-2(L)Cl-3](+) tectons with distinct N3CuCl2 and N4CuCl2 centres in the solid. The overall structures of the dicopper bromide and chloride units persist in solution irrespective of the halide. The redox chemistry of the various species is also described

Multicomponent Compatibility and its Verification

Software architecture has been introduced with promise of better re-use of software, greater flexibility, scalability and higher quality of software services. Software architecture uses components as the basic building blocks of software systems. Components represent high-level software models; they must be generic enough to work in a variety of contexts and in cooperation with other components, but they also must be specific enough to provide easy reuse. To be composable with other (third-party) components, a component needs to be sufficiently self-contained. Also, it needs a clear specification of what it requires and what it provides. In other words, a component needs to encapsulate its implementation and interact with its environment by means of well-defined interfaces

Tetra­phenyl­phospho­nium hydrogen oxalate

In the title compound, C24H20P+·C2HO4 −, two symmetry-independent ion pairs are present. The cations aggregate into puckered sheets via zigzag infinite chains of sixfold phenyl embraces and parallel fourfold phenyl embraces, while the anions form hydrogen-bonded chains between the sheets of cations. In the two independent oxalate anions, the angles between the normals to the two least-squares carboxyl­ate COO planes are unusually large, viz. 72.5 (1) and 82.1 (1)°

7α,15α-Dibromo-8,16-diphenyl-6,7,14,15-tetra­hydro-6α,14α-epithio­cyclo­octa­[1,2-b:5,6-b′]diquinoline deuterochloro­form solvate

In the racemic title compound, C34H22Br2N2S·CDCl3, pairs of diquinoline host mol­ecules form centrosymmetric brick-like dimers utilizing three different aryl edge-to-face inter­actions (EF1–3). The dimeric (EF)6 (i.e. 2 × EF1–3) building blocks pack with the deuterochloro­form guest mol­ecules positioned near each of their corners. The Cl atoms of the latter are disordered over two sets of sites in a 0.53 (2):0.47 (2) ratio

(1R*,2R*,4S*,5R*,6R*,8S*)-4,8-Dimethyl-2,6-diphenyl­bicyclo­[3.3.1]nonane-2,6-diol

The racemic title compound, C23H28O2, crystallizes in the space group C2/c as a layered structure in which a centrosymmetric three hydrogen bond sequence links four molecules. Both hydroxy groups are involved in this arrangement, but they differ in that one participates in two hydrogen bonds while the other takes part in only one. Between layers, the aromatic rings take part in edge-face interactions [shortest C—H⋯C distances 3.04, 3.10 and 3.12 Å and angle between normal to planes 86.7(2)°], forming a centrosymmetric dimer. The lattice is further stabilized by C—H⋯π interactions involving both methyl (shortest C⋯C 3.82 and 3.97 Å) and methylene (shortest C⋯C 3.60 Å) groups

Deep Near-Infrared Observations of L1014: Revealing the nature of the core and its embedded source

Recently, the Spitzer Space Telescope discovered L1014-IRS, a mid-infrared source with protostellar colors, toward the heretofore "starless" core L1014. We present deep near-infrared observations that show a scattered light nebula extending from L1014-IRS. This nebula resembles those typically associated with protostars and young stellar objects, tracing envelope cavities presumably evacuated by an outflow. The northern lobe of the nebula has an opening angle of ~100 degrees, while the southern lobe is barely detected. Its morphology suggests that the bipolar cavity and inferred protostellar disk is not inclined more than 30 degrees from an edge-on orientation. The nebula extends at least 8" from the source at Ks, strongly suggesting that L1014-IRS is embedded within L1014 at a distance of 200 pc rather than in a more distant cloud associated with the Perseus arm at 2.6 kpc. In this case, the apparently low luminosity of L1014-IRS, 0.090 Lsun, is consistent with it having a substellar mass. However, if L1014-IRS is obscured by a circumstellar disk, its luminosity and inferred mass may be greater. Using near-infrared colors of background stars, we investigate characteristics of the L1014 molecular cloud core. We determine a mass of 3.6 Msun for regions of the core with Av > 2 magnitudes. A comparison of the radial extinction profile of L1014 with other cores suggests that L1014 may be among the most centrally condensed cores known, perhaps indicative of the earliest stages of brown dwarf or star formation processes.Comment: Replacement includes revision to mass of core. 22 pages, 6 figures. Accepted by Ap

2,8-Dimethyl­tricyclo­[5.3.1.13,9]dodecane-syn-2,syn-8-diol–propanoic acid (1/1)

The racemic title compound, C14H24O2·C3H6O2, crystallizes in the monoclinic space group P21/c as a 1:1 diol/carboxylic acid cocrystal, A–B. The lattice incorporates infinite chains of the alcohol–carboxylic acid–alcohol supra­molecular synthon, (⋯O—H⋯O=C(R)—O—H⋯O—H⋯), in which the hydrogen-bonded mol­ecules (A—B—A)n surround a pseudo-threefold screw axis. The carboxylic acid group functions like an extended alcohol hydr­oxy group. Each diol, A, takes part in two such threefold screw arrangements, leading to a hydrogen-bonded layer structure, with adjacent layers containing diol mol­ecules of opposite handedness. The central C atom of the propano bridge is disordered over two sites of occupancies 0.75 (1) and 0.25 (1). The methyl group of the propanoic acid molecule is disordered over two sites of occupancies 0.68 (1) and 0.32 (1)