105,697 research outputs found
Sustainable and solar light assisted photocatalytic degradation of methylene blue and malachite green dyes by Co3O4/g-C3N4 nanocomposite
No full textCo3O4 nanoparticles were prepared by a simple co-precipitation method and subsequently hybridized with various weight percentages of g-C3N4 by a facile mixing method. The Co3O4/(x)g-C3N4 (where, x = 10, 20 and 30%) composites were analysed by several analytical techniques (XRD, TEM, FE-SEM, EDS, FT-IR, UV–Vis -DRS, XPS, PL, and BET surface area) to investigate their chemical composition, as well as morphological and optical characteristics. The photocatalytic degradation of methylene blue (MB) and malachite green (MG) was investigated by the Co3O4/(x)g-C3N4 with changing parameters, such as pH, catalyst dose, initial dye concentration and agitation time under solar light irradiation. Amongst the tested catalysts Co3O4/(20)g-C3N4 exhibited highest photo-degradation of MB dye (97%) at pH ∼ 11 and for MG (98%) at pH ∼ 9 in 60 min compared to 85 and 88% respectively for neat Co3O4 and 89 and 86% respectively for pure g-C3N4. The radical detection test was carried out with trapping agents Na2-EDTA, BQ and IPA that established the vital role of hydroxyl radicals in the photo-degradation of dyes. Eventually, the high stability and recyclability of the Co3O4/(20)g-C3N4 photocatalyst was confirmed after five consecutive runs. The mechanistic pathway of the dye degradation was explained by Z-scheme model on the basis of p-n hetero-junction
Locally Computing Edge Orientations
No full textWe consider the question of orienting the edges in a graph G such that every vertex has bounded out-degree. For graphs of arboricity α, there is an orientation in which every vertex has out-degree at most α and, moreover, the best possible maximum out-degree of an orientation is at least α - 1. We are thus interested in algorithms that can achieve a maximum out-degree of close to α. A widely studied approach for this problem in the distributed algorithms setting is a "peeling algorithm" that provides an orientation with maximum out-degree α(2+ε) in a logarithmic number of iterations.
We consider this problem in the local computation algorithm (LCA) model, which quickly answers queries of the form "What is the orientation of edge (u,v)?" by probing the input graph. When the peeling algorithm is executed in the LCA setting by applying standard techniques, e.g., the Parnas-Ron paradigm, it requires Ω(n) probes per query on an n-vertex graph. In the case where G has unbounded degree, we show that any LCA that orients its edges to yield maximum out-degree r must use Ω(√ n/r) probes to G per query in the worst case, even if G is known to be a forest (that is, α = 1). We also show several algorithms with sublinear probe complexity when G has unbounded degree. When G is a tree such that the maximum degree Δ of G is bounded, we demonstrate an algorithm that uses Δ n^{1-log_Δ r + o(1)} probes to G per query. To obtain this result, we develop an edge-coloring approach that ultimately yields a graph-shattering-like result. We also use this shattering-like approach to demonstrate an LCA which 4-colors any tree using sublinear probes per query
Bibliographie Hilarion G. Petzold 1958 – 2009 mit Anhang als Einführung
No full textDieses Archiv enthält die Gesamtbibliographie der Werke des Autors nebst einiger Texte „Über H. G. Petzold“ im Schlussteil der Bibliographie sowie einen Anhang mit einer Einführung in die Architektur des Werkes in seinem wissenslogischen Aufbau als Ausarbeitung seines „Tree of Science Modells“ (2007).This archive contains the complete bibliography of the author and some texts about H. G. Petzold, moreover an epilogue with an introduction to the architecture of the works in its epistemological structure and composition and as an elaborations of Petzold’s „Tree of Science Modell (2007).https://www.fpi-publikation.de/polyloge/01-2009-petzold-h-g-gesamtbibliographie-h-g-petzold-1958-2009-updating-november2009/peerReviewedpublishedVersio
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Deformation theory of nearly G₂-structures and nearly G₂ instantons
No full textWe study two different deformation theory problems on manifolds with a nearly G₂-structure. The first involves studying the deformation theory of nearly G₂ manifolds. These are seven dimensional manifolds admitting real Killing spinors. We show that the infinitesimal deformations of nearly G₂-structures are obstructed in general. Explicitly, we prove that the infinitesimal deformations of the homogeneous nearly G₂-structure on the Aloff–Wallach space are all obstructed to second order. We also completely describe the de Rham cohomology of nearly G₂ manifolds.
In the second problem we study the deformation theory of G₂ instantons on nearly G₂ manifolds. We make use of the one-to-one correspondence between nearly parallel G₂-structures and real Killing spinors to formulate the deformation theory in terms of spinors and Dirac operators. We prove that the space of infinitesimal deformations of an instanton is isomorphic to the kernel of an elliptic operator. Using this formulation we prove that abelian instantons are rigid. Then we apply our results to explicitly describe the deformation space of the canonical connection on the four normal homogeneous nearly G₂ manifolds.
We also describe the infinitesimal deformation space of the SU(3) instantons on Sasaki–Einstein 7-folds which are nearly G₂ manifolds with two Killing spinors. A Sasaki–Einstein structure on a 7-dimensional manifold is equivalent to a 1-parameter family of nearly G₂-structures. We show that the deformation space can be described as an eigenspace of a twisted Dirac operator
Recommended from our members
3346: Samuel G. Freedman, author, 2013
No full textPhotograph of author Samuel G. Freedman, at NT Daily Slash meeting in the Mayborn School of Journalism at UNT
On the Impossibility of Min-Process Non-Blocking Checkpointing and an Efficient Checkpointing Algorithm for Mobile Computing Systems
No full textMobile computing raises many new issues, such as lack of stable storage, low bandwidth of wireless channel, high mobility, and limited battery life. These new issues make traditional checkpointing algorithms unsuitable. Prakash and Singhal [14] proposed the first coordinated checkpointing algorithm for mobile computing systems. However, we showed that their algorithm may result in an inconsistency [3]. In this paper, we prove a more general result about coordinated checkpointing: there does not exist a non-blocking algorithm that forces only a minimum number of processes to take their checkpoints. Based on the proof, we propose an efficient algorithm for mobile computing systems, which forces only a minimum number of processes to take checkpoints and dramatically reduces the blocking time during the checkpointing process. Correctness proofs and performance analysis of the algorithm are provided
Factors affecting prepubertal growth in homozygous sickle cell disease
No full textOBJECTIVE:To investigate the role of haematological indices, socioeconomic status, and morbidity in prepubertal growth in homozygous sickle cell (SS) disease.METHOD:Height, weight, and haematology were serially recorded in a cohort study of 315 children with SS disease from birth to 9 years at the sickle cell clinic of the University Hospital of the West Indies, Kingston, Jamaica.RESULTS:Height increment between 3 and 9 years correlated positively with total haemoglobin at age 7 years in boys but not girls. Attained height and weight at age 7 years correlated positively with haemoglobin and fetal haemoglobin in boys but not girls. Only the correlation between haemoglobin and weight showed a significant gender difference. Partial correlation analysis suggested that the effect of haemoglobin was accounted for by the effect of fetal haemolglobin and further analysis indicated that height correlated with F reticulocyte count (a measure of fetal haemoglobin production) in both sexes but not with the ratio of F cells to F reticulocytes (a measure of F cell enrichment). Growth was not significantly related to mean red cell volume, proportional reticulocyte count, alpha thalassaemia, socioeconomic status, or morbidity.CONCLUSION:A high concentration of fetal haemoglobin in boys with SS disease is associated with greater linear growth. It is postulated that in boys, low concentrations of fetal haemoglobin increase haemolysis and hence metabolic requirements for erythropoiesis, putting them at greater risk of poor growth. Differences in the relationship of haematology and growth between boys and girls with SS disease dictate that future analyses of growth take gender into account
- …
