Drawing Graphs within Restricted Area

We study the problem of selecting a maximum-weight subgraph of a given graph such that the subgraph can be drawn within a prescribed drawing area subject to given non-uniform vertex sizes. We develop and analyze heuristics both for the general (undirected) case and for the use case of (directed) calculation graphs which are used to analyze the typical mistakes that high school students make when transforming mathematical expressions in the process of calculating, for example, sums of fractions

Properties of metabolic graphs: biological organization or representation artifacts?

<p>Abstract</p> <p>Background</p> <p>Standard graphs, where each edge links two nodes, have been extensively used to represent the connectivity of metabolic networks. It is based on this representation that properties of metabolic networks, such as hierarchical and small-world structures, have been elucidated and null models have been proposed to derive biological organization hypotheses. However, these graphs provide a simplistic model of a metabolic network's connectivity map, since metabolic reactions often involve more than two reactants. In other words, this map is better represented as a hypergraph. Consequently, a question that naturally arises in this context is whether these properties truly reflect biological organization or are merely an artifact of the representation.</p> <p>Results</p> <p>In this paper, we address this question by reanalyzing topological properties of the metabolic network of <it>Escherichia coli </it>under a hypergraph representation, as well as standard graph abstractions. We find that when clustering is properly defined for hypergraphs and subsequently used to analyze metabolic networks, the scaling of clustering, and thus the hierarchical structure hypothesis in metabolic networks, become unsupported. Moreover, we find that incorporating the distribution of reaction sizes into the null model further weakens the support for the scaling patterns.</p> <p>Conclusions</p> <p>These results combined suggest that the reported scaling of the clustering coefficients in the metabolic graphs and its specific power coefficient may be an artifact of the graph representation, and may not be supported when biochemical reactions are atomically treated as hyperedges. This study highlights the implications of the way a biological system is represented and the null model employed on the elucidated properties, along with their support, of the system.</p

De novo implantation vs. upgrade cardiac resynchronization therapy: a systematic review and meta-analysis

Patients with conventional pacemakers or implanted defibrillators are often considered for cardiac resynchronization therapy (CRT). Our aim was to summarize the available evidences regarding the clinical benefits of upgrade procedures. A systematic literature search was performed from studies published between 2006 and 2017 in order to compare the outcome of CRT upgrade vs. de novo implantations. Outcome data on all-cause mortality, heart failure events, New York Heart Association (NYHA) Class, QRS narrowing and echocardiographic parameters were analysed. A total of 16 reports were analysed comprising 489,568 CRT recipients, of whom 468,205 patients underwent de novo and 21,363 upgrade procedures. All-cause mortality was similar after CRT upgrade compared to de novo implantations (RR 1.19, 95% CI 0.88-1.60, p = 0.27). The risk of heart failure was also similar in both groups (RR 0.96, 95% CI 0.70-1.32, p = 0.81). There was no significant difference in clinical response after CRT upgrade compared to de novo implantations in terms of improvement in left ventricular ejection fraction (DeltaEF de novo - 6.85% vs. upgrade - 9.35%; p = 0.235), NYHA class (DeltaNYHA de novo - 0.74 vs. upgrade - 0.70; p = 0.737) and QRS narrowing (DeltaQRS de novo - 9.6 ms vs. upgrade - 29.5 ms; p = 0.485). Our systematic review and meta-analysis of currently available studies reports that CRT upgrade is associated with similar risk for all-cause mortality compared to de novo resynchronization therapy. Benefits on reverse remodelling and functional capacity improved similarly in both groups suggesting that CRT upgrade may be safely and effectively offered in routine practice. CLINICAL TRIAL REGISTRATION: Prospero Database-CRD42016043747

A calorimetric study of pTS (bis-p-toluenesulphonate of 2,4-hexadiyne 1,6-diol) and its phase transitions as a function of polymerization

The specific heat Cp of pTS was measured from 135 to 225 K, for polymer contents 0 ≲ p ≲ 1. For p ≲ 0.01, two endotherms near 156 and 192 K limit the incommensurable phase. For p ≳ 0.01, two other transitions occur near 161 and 182 K. The corresponding enthalpies decrease from about 25 to less than 1 cal./mol, and the transitions are no longer detected for p ≳ 0.04 (182 and 192 K) and for p ≳ 0.12 (150 and 161 K). For p > 0.95 a transition is again observed near 189 K with ΔH ∼ 10 cal./mol.On a mesuré la chaleur spécifique de pTS entre 135 et 225 K, pour des taux de polymère 0 ≲ p ≲ 1. Pour p ≲ 0,01, deux endothermes entre 156 et 192 K limitent la phase incommensurable. Pour 0,01 ≲ p deux autres transitions s'y ajoutent vers 161 et 182 K. Les enthalpies correspondantes diminuent de 25 à moins de 1 cal./mole et les transitions cessent d'être observables à p > 0,04 (182 et 192 K) ou 0,12 (150 et 161 K). Une transition est à nouveau observable vers 189 K pour p ≳ 0,95, avec ΔH ∼ 10 cal./mole

Détermination du moment angulaire de quelques états du radon 219 et du polonium 215

The multipolarities of the 269 keV transition of Rn 219 and of the 272 keV transition of Po 215 have been determined from measurements of conversion electron ratios K/L and K/L + M. Thèse results have authorized the interpretation of α-γ angular correlation measurements and the spin assignment of 5/2 for the 269 keV level of Rn 219 and the 272 keV of Po 215. The nature of these levels is looked at and the mean-life of Po 215 has been measured.Les multipolarités des transitions électromagnétiques de 269 keV du Rn 219 et de 272 keV du Po 215 ont été déduites des mesures des rapports de coefficient de conversion K/L et K/L + M. Ceci a permis d'interpréter les mesures de corrélation angulaire (α-γ) et de déterminer la valeur 5/2 pour le moment angulaire du niveau de 269 keV du Rn 219 et du niveau de 272 keV du Po 215. La nature de ces niveaux est envisagée et la période du niveau de 272 keV de Po 215 a été mesurée

Experimental Evidence on the Influence of Extended Defects on a Structural Phase Transition: Polymer Chains in a Monomer Matrix

The influence of the polymerization on the static aspects of the structural phase transition in a monomer-polymer pTS-diacetylene system is studied by neutron scattering. The disorder arises probably from the frustration of the incommensurate modulation present in the pure monomer; the influence of the polymer chains acting as extended defects appears the determining factor in the observed phenomena.Nous étudions les aspects statiques des transitions de phase dans un système mixte monomère-polymère par diffusion de neutrons. Le désordre provient probablement d'une frustration de la modulation incommensurable qui existe dans les cristaux de monomère pur. L'influence des défauts étendus que constituent les chaines de polymètres est le facteur prépondérant qui apparait dans les phénomènes observés