The Trapping and Characterization of a Single Hydrogen Molecule in a Continuously Tunable Nanocavity

Using inelastic electron tunneling spectroscopy with the scanning tunneling microscope (STM-IETS) and density functional theory calculations (DFT), we investigated properties of a single H2 molecule trapped in nanocavities with controlled shape and separation between the STM tip and the Au (110) surface. The STM tip not only serves for the purpose of characterization, but also is directly involved in modification of chemical environment of molecule. The bond length of H2 expands in the atop cavity, with a tendency of dissociation when the gap closes, whereas it remains unchanged in the trough cavity. The availability of two substantially different cavities in the same setup allows understanding of H2 adsorption on noble metal surfaces and sets a path for manipulating a single chemical bond by design.Comment: 11 pages, 4 figure

The Effects of Service-Learning Participation on Pre-Internship Educators’ Teachers’ Sense of Efficacy

This study aimed to determine if pre-internship teacher education students’ participation in service-learning activities in K-12 classrooms would significantly affect their teachers’ sense of efficacy (TSE). A secondary focus sought to determine if one type of service-learning activity (e.g., whole-class instruction) would affect teacher efficacy more than another (e.g., small-group tutoring). Findings revealed that pre-internship service-learners in both types of service-learning activities increased significantly in their TSE. However, neither type of service-learning activity was superior to the other as measured by the minimally accepted .05 level. The discussion focuses on factors shared between the two service-learning designs that might mediate a positive mastery experience.L’objectif de cette étude était de déterminer si la participation par des étudiants en pédagogie à des activités de bénévolat dans des classes de la maternelle à la 12e année augmenterait de façon significative leur sentiment d’être efficaces comme enseignants. Un deuxième objectif consistait à déterminer si un type d’activité de bénévolat (par ex. l’enseignement à toute la classe) affecterait l’efficacité d’un enseignant plus qu’une autre (par ex. le tutorat à de petits groupes). Les résultats indiquent que les deux types d’activité ont accru de façon significative le sentiment d’efficacité comme enseignants chez les étudiants bénévoles. Toutefois, les paramètres selon le seuil minimal de 0,05 ont révélé qu’aucune activité n’était supérieure à l’autre. La discussion porte sur des facteurs communs aux deux activités de bénévolat et qui pourraient entrainer une expérience d’apprentissage fructueuse

GeneFishing to reconstruct context specific portraits of biological processes.

Rapid advances in genomic technologies have led to a wealth of diverse data, from which novel discoveries can be gleaned through the application of robust statistical and computational methods. Here, we describe GeneFishing, a semisupervised computational approach to reconstruct context-specific portraits of biological processes by leveraging gene-gene coexpression information. GeneFishing incorporates multiple high-dimensional statistical ideas, including dimensionality reduction, clustering, subsampling, and results aggregation, to produce robust results. To illustrate the power of our method, we applied it using 21 genes involved in cholesterol metabolism as "bait" to "fish out" (or identify) genes not previously identified as being connected to cholesterol metabolism. Using simulation and real datasets, we found that the results obtained through GeneFishing were more interesting for our study than those provided by related gene prioritization methods. In particular, application of GeneFishing to the GTEx liver RNA sequencing (RNAseq) data not only reidentified many known cholesterol-related genes, but also pointed to glyoxalase I (GLO1) as a gene implicated in cholesterol metabolism. In a follow-up experiment, we found that GLO1 knockdown in human hepatoma cell lines increased levels of cellular cholesterol ester, validating a role for GLO1 in cholesterol metabolism. In addition, we performed pantissue analysis by applying GeneFishing on various tissues and identified many potential tissue-specific cholesterol metabolism-related genes. GeneFishing appears to be a powerful tool for identifying related components of complex biological systems and may be used across a wide range of applications

Simultaneous measurements of Ca2+ in the intracellular stores and the cytosol of hepatocytes during hormone-induced Ca2+ oscillations

AbstractSimultaneous Ca2+ measurements in the cytosol and intracellular stores (IS) of rat hepatocytes were performed using two Ca2+-sensitive probes (Fluo-3 and Mag-fura-2), and combined whole-cell patch clamp and fluorescence microscopy. A steady-state Ca2+ concentration of ∼630 μM was estimated in the IS. α1-Adrenergic stimulation induced periodic elevations of cytosolic Ca2+ and parallel synchronized transient declines in the IS. Subsequent application of the intracellular Ca2+-pump inhibitor thapsigargin resulted in a release of Ca2+ from the IS to reach a level of Ca2+ depletion much lower than the lowest transient decline observed during the oscillations

A matrix-based approach to searching colored paths in a weighted colored multidigraph

An algebraic approach to finding all edge-weighted-colored paths within a weighted colored multidigraph is developed. Generally, the adjacency matrix represents a simple digraph and determines all paths between any two vertices, and is not readily extendable to colored multidigraphs. To bridge the gap, a conversion function is proposed to transform the original problem of searching edge-colored paths in a colored multidigraph to a standard problem of finding paths in a simple digraph. Moreover, edge weights can be used to represent some preference attribute. Its potentially wide realm of applicability is illustrated by a case study: status quo analysis in the graph model for conflict resolution. The explicit matrix function is more convenient than other graphical representations for computer implementation and for adapting to other applications. Additionally, the algebraic approach reveals the relationship between a colored multidigraph and a simple digraph, thereby providing new insights into algebraic graph theory

A matrix approach to status quo analysis in the graph model for conflict resolution

An algebraic method is developed to carry out status quo analysis within the framework of the graph model for conflict resolution. As a form of post-stability analysis, status quo analysis aims at confirming that possible equilibria, or states stable for all decision-makers, are in fact reachable from the status quo or any other initial state. Although pseudo-codes for status quo analysis have been developed, they have never been implemented within a practical decision support system. The novel matrix approach to status quo analysis designed here is convenient for computer implementation and easy to employ, as is illustrated by an application to a real-world conflict case. Moveover, the proposed explicit matrix approach reveals an inherent link between status quo analysis and the traditional stability analysis and, hence, provides the possibility of establishing an integrated paradigm for stability and status quo analyses

A DEA-TOPSIS method for multiple criteria decision analysis in emergency management

A hybrid approach of DEA (data envelopment analysis) and TOPSIS (technique for order performance (preference) by similarity to ideal solution) is proposed for multiple criteria decision analysis in emergency management. Two DEA-based optimization models are constructed to facilitate identifying parameter information regarding criterion weights and quantifying qualitative criteria in TOPSIS. An emergency management case study utilizing data from the Emergency Management Australia (EMA) Disasters Database is provided to demonstrate the feasibility of the proposed analysis procedure

Piperine derivatives enhance fusion and axonal transport of mitochondria by activating mitofusins

Piperine (1-piperoylpiperidine) is the major pungent component of black pepper (Piper nigrum) and exhibits a spectrum of pharmacological activities. The molecular bases for many of piperine’s biological effects are incompletely defined. We noted that the chemical structure of piperine generally conforms to a pharmacophore model for small bioactive molecules that activate mitofusin (MFN)-mediated mitochondrial fusion. Piperine, but not its isomer chavicine, stimulated mitochondrial fusion in MFN-deficient cells with EC50 of ~8 nM. We synthesized piperine analogs having structural features predicted to optimize mitofusin activation and defined structure-activity relationships (SAR) in live-cell mitochondrial elongation assays. When optimal spacing was maintained between amide and aromatic groups the derivatives were potent mitofusin activators. Compared to the prototype phenylhexanamide mitofusin activator, 2, novel molecules containing the piperidine structure of piperine exhibited markedly enhanced passive membrane permeability with no loss of fusogenic potency. Lead compounds 5 and 8 enhanced mitochondrial motility in cultured murine Charcot-Marie-Tooth disease type 2A (CMT2A) neurons, but only 8 improved mitochondrial transport in sciatic nerve axons of CMT2A mice. Piperine analogs represent a new chemical class of mitofusin activators with potential pharmaceutical advantages