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  • 1
    Publication Date: 2017-05-12
    Description: Author(s): Yu He, X. Ding, Z.-E. Su, H.-L. Huang, J. Qin, C. Wang, S. Unsleber, C. Chen, H. Wang, Y.-M. He, X.-L. Wang, W.-J. Zhang, S.-J. Chen, C. Schneider, M. Kamp, L.-X. You, Z. Wang, S. Höfling, Chao-Yang Lu, and Jian-Wei Pan Boson sampling is a problem strongly believed to be intractable for classical computers, but can be naturally solved on a specialized photonic quantum simulator. Here, we implement the first time-bin-encoded boson sampling using a highly indistinguishable ( ∼ 94 % ) single-photon source based on a singl… [Phys. Rev. Lett. 118, 190501] Published Wed May 10, 2017
    Keywords: General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.
    Print ISSN: 0031-9007
    Electronic ISSN: 1079-7114
    Topics: Physics
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  • 2
    Publication Date: 2005-02-07
    Print ISSN: 0003-6951
    Electronic ISSN: 1077-3118
    Topics: Physics
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  • 3
    Publication Date: 2020-05-01
    Print ISSN: 0034-6748
    Electronic ISSN: 1089-7623
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
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  • 4
    ISSN: 1520-510X
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1520-510X
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Algorithmica 25 (1999), S. 176-195 
    ISSN: 1432-0541
    Keywords: Key words. Evolutionary trees, Approximation algorithms, Lower bounds.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract. Different phylogenetic trees for the same group of species are often produced either by procedures that use diverse optimality criteria [16] or from different genes [12] in the study of molecular evolution. Comparing these trees to find their similarities and dissimilarities (i.e., distance ) is thus an important issue in computational molecular biology. Several distance metrics including the nearest neighbor interchange (nni) distance and the subtree-transfer distance have been proposed and extensively studied in the literature. This article considers a natural extension of the subtree-transfer distance, called the linear-cost subtree-transfer distance, and studies the complexity and efficient approximation algorithms for this distance as well as its relationship to the nni distance. The linear-cost subtree-transfer model seems more suitable than the (unit-cost) subtree-transfer model in some applications. The following is a list of our results: 1. The linear-cost subtree-transfer distance is in fact identical to the nni distance on unweighted phylogenies. 2. There is an algorithm to compute an optimal linear-cost subtree-transfer sequence between unweighted phylogenies in O(n ⋅ 2 O(d) ) time, where d denotes the linear-cost subtree-transfer distance. Such an algorithm is useful when d is small. 3. Computing the linear-cost subtree-transfer distance between two weighted phylogenetic trees is NP-hard, provided we allow multiple leaves of a tree to share the same label (i.e., the trees are not necessarily uniquely labeled). 4. There is an efficient approximation algorithm for computing the linear-cost subtree-transfer distance between weighted phylogenies with performance ratio 2 .
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Algorithmica 19 (1997), S. 354-368 
    ISSN: 1432-0541
    Keywords: Key words. Parallel algorithms, Maximal acyclic sets, Planar graphs.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract. Given a graph G=(V,E), the well-known spanning forest problem of G can be viewed as the problem of finding a maximal subset F of edges in G such that the subgraph induced by F is acyclic. Although this problem has well-known efficient NC algorithms, its vertex counterpart, the problem of finding a maximal subset U of vertices in G such that the subgraph induced by U is acyclic, has not been shown to be in NC (or even in RNC) and is not believed to be parallelizable in general. In this paper we present NC algorithms for solving the latter problem for two special cases. First, we show that, for a planar graph with n vertices, the problem can be solved in $O(\log^3 n)$ time with O(n) processors on an EREW PRAM. Second, we show that the problem is solvable in NC if the input graph G has only vertex-induced paths of length polylogarithmic in the number of vertices of G. As a consequence of this result, we show that certain natural extensions of the well-studied maximal independent set problem remain solvable in NC. Moreover, we show that, for a constant-degree graph with n vertices, the problem can be solved in $O(\sqrt{n}\log^3n)$ time with O(n 2 ) processors on an EREW PRAM.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Biology and fertility of soils 11 (1991), S. 145-150 
    ISSN: 1432-0789
    Keywords: Nitrogen-15 ; Ammonia fixation ; Organic matter-fixed NH3 ; Clay-fixed NH inf4 sup+
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The application of liquid anhydrous NH3 to soil leads to chemical fixation of NH3 by organic matter and of NH inf4 sup+ by clay minerals. A laboratory study was conducted to ascertain the biological transformations of newly fixed liquid anhydrous 15NH3 in a Drummer silty clay loam by incubation of the 15N-labelled soil with glucose for 0, 7, 30, and 90 days and by sequential extraction of organic-matter-fixed 15NH3 with 0.15 M Na4P2O7, 0.15 M KOH, 0.1 M NaOH, and acidified dimethyl sulfoxide. About 16% of the 15NH3 injected was fixed, of which 52% was accounted for by clay fixation. The various humic fractions (fulvic acid, humic acid, and humin) were obtained, and the distribution patterns of the fixed 15NH3-N in these fractions were compared. The potential availability of the fixed 15NH3-N was also estimated. The percentage of the 15NH3 recovered as organic-matter-fixed 15NH3 decreased as the length of incubation increased (to 28% after 90 days); the decrease was attributed in part to an increase in the amount recovered as clay-fixed NH inf4 sup+ (from 52 to 64%). Changes in the distribution of the organic-matter-fixed 15NH3-N in the humic fractions included: (1) an increase in the relative amount of the fixed 15NH3 as humic acid in both the Na4P2O7 and KOH extracts, (2) an increase in the percentage of organic-matter-fixed 15NH3-N in the fulvic acid fractions as high-molecular-weight components (determined by dialysis) or as generic fulvic acid (determined by sorption-desorption from XAD-8 resin), and (3) an increase in the percentage of the organic-matter-fixed 15NH3 as humin. The potential availability of the organic-matter-fixed 15NH3-N decreased as the length of the incubation increased, from 22 to 4% over the 90-day incubation period, and was correlated significantly (0.05 level) with Na4P2O7-extractable N. These results suggest that organic-matter-fixed liquid anhydrous NH3 is initially more labile than the native soil N but becomes less labile with time.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 330-332 (Feb. 2007), p. 975-978 
    ISSN: 1013-9826
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: An environmentally friendly direct foaming method was investigated to produce porousalumina ceramics. Egg white protein was used as a binder and foaming agent. The microstructuresshow that pores are interconnected with pore size of a few hundreds μm and pore window size of ca.50 μm. The compressive strength of alumina foam is up to 100 MPa depending on porosity.Bioactivation of alumina was carried out using an alkaline solution treatment. Hydroxylation ofalumina was achieved using 5M NaOH at 80°C for 4 days. In vitro assessments of the alumina in ahuman osteoblast cell-like cell (MG63) culture showed that the bioactivated alumina foamsexhibited better cellularity and alkaline phosphatase (ALP) activity compared to untreated aluminafoams. The results indicate that it is possible to improve the osseointgration of alumina ceramics bystructural and surface modifications and to extend the applications of biocompatible aluminaceramics in biomedical implants and tissue engineering scaffolds
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 41 (1985), S. 244-251 
    ISSN: 1600-5724
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: The established procedure for analyzing molecular vibrations in terms of normal modes has been adapted so that experimental anisotropic thermal parameters can be used to study low-frequency internal vibrations of simple molecules in crystals. This involves quasinormal modes, which are linear combinations of selected low-frequency internal modes such as the torsional librations about individual bonds. Higher-frequency modes are neglected, since their contribution to the atomic mean-square displacements should be small. The force constants for selected low- frequency internal modes, together with the tensor components (T,L,S) that describe the overall molecular vibration, become the variables in an iterative least-squares refinement in which the observations are the atomic Uij values. As a result, the concerted motion of the atoms for each quasinormal mode is defined and also its vibrational frequency. Corrections to bond lengths and angles due to internal vibrations can be calculated. In tests involving two different lipid crystal structures, the internal motions were introduced as torsions about two or three bonds occurring near the junction of an extended hydrocarbon chain with a relatively rigid massive atomic grouping. Compared with the simple rigid-body model, there were highly significant improvements in agreement between experimental and calculated Uij values. Force constants for torsion about three C-S bonds were also in agreement [26 (5), 23 (6) and 22 (6) J mol-1 deg-2]. In one of the crystal structures (determined at 123 K), the six C-C bonds of a paraffin chain have average lengths 1.526 (2) Å before correction, 1.527 (3) Å after correction for simple rigid-body libration and 1.536 (4) Å after corrections including the quasinormal vibrations. The latter agrees with the electron diffraction value 1.542 (4) Å for n-hexadecane.
    Type of Medium: Electronic Resource
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