4,124 research outputs found
Building for the Long Term
Endowed professorships support the work of select faculty -- and help to attract talented new professors
Tuning the excited state of photoactive building blocks for metal-templated self-assembly.
The reaction of 2,2':4,4'':4',4'''-quaterpyridyl (qtpy), with d(6) ruthenium(II) (Ru(II) ), and rhenium(I) (Re(I) ) metal centers has been investigated. The pendant pyridyl groups on the products have also been methylated to produce a second series of complexes containing coordinated Meqtpy(2+). The absorption spectra of the complexes are dominated by intraligand and charge-transfer bands. The ruthenium(II) complexes display broad unstructured luminescence consistent with emission from a Ru(d)→diimine(π*) manifold in acetonitrile solutions. In aqueous solutions, their emissions are weaker and the lifetimes are shorter. This effect is particularly acute for complexes incorporating coordinated dipyridylpyrazine, dppz, ligands. Although the emission of the ruthenium(II) complexes containing Meqtpy(2+) is generally shorter than their qtpy analogs, it is notable that solvent-dependent effects are much less intense. The rhenium(I) complexes also display broad unstructured luminescence but, compared with the ruthenium(II) systems, they have a relatively short lifetime in acetonitrile. Electrochemical studies reveal that all of the Ru(II) complexes display chemically reversible metal-based oxidations. Re(I) complexes only display irreversible metal-based oxidations. In most cases, the reduction processes were not fully chemically reversible. The electrochemical and optical studies reveal that the nature of the lowest excited state of these complexes--particularly, the systems incorporating dppz--is highly dependent on the nature of the coordinated ligands. Calculations indicate that, although the excited state of most of the complexes is centered on the qtpy or Meqtpy(2+) ligands, the excited state of the complexes containing dppz ligands is switched away from the dppz by qtpy methylation. A crystallographic study on one of the dicationic ruthenium(II) structures reveals that it forms an inclusion complex with benzene
From Visualization to Visually Enabled Reasoning
Interactive Visualization has been used to study scientific phenomena, analyze data, visualize information, and to explore large amounts of multi-variate data. It enables the human mind to gain novel insights by empowering the human visual system, encompassing the brain and the eyes, to discover properties that were previously unknown. While it is believed that the process of creating interactive visualizations is reasonably well understood, the process of stimulating and enabling human reasoning with the aid of interactive visualization tools is still a highly unexplored field.
We hypothesize that visualizations make an impact if they successfully influence a thought process or a decision. Interacting with visualizations is part of this process. We present exemplary cases where visualization was successful in enabling human reasoning, and instances where the interaction with data helped in understanding the data and making a better informed decision.
We suggest metrics that help in understanding the evolution of a decision making process. Such a metric would measure the efficiency of the reasoning process, rather than the performance of the visualization system or the user. We claim that the methodology of interactive visualization, which has been studied to a great extent, is now sufficiently mature, and we would like to provide some guidance regarding the evaluation of knowledge gain through visually enabled reasoning. It is our ambition to encourage the reader to take on the next step and move from information visualization to visually enabled reasoning
Finite Temperature Lattice QCD with Clover Fermions
We report on our simulation of finite temperature lattice QCD with two
flavors of Symanzik-improved fermions and
Symanzik-improved glue. Our thermodynamic simulations were performed on an lattice, and we have performed complementary zero temperature
simulations on an lattice. We compare our results to those from
simulations with two flavors of Wilson fermions and discuss the improvement
resulting from use of the improved action.Comment: 3 pages, 4 figures, Talk presented at Lattice 9
Exotic hybrid mesons with light quarks
Hybrid mesons, made from a quark, an antiquark and gluons, can have quantum
numbers inaccessible to conventional quark-antiquark states. Confirmation of
such states would give information on the role of "dynamical" color in low
energy QCD. We present preliminary results for hybrid meson masses using light
Wilson valence quarks.Comment: 4 pages, 4 figures, Talk presented at LATTICE96(spectrum
A qualitative investigation of obese men\u27s experiences with their weight
Objectives: To investigate obese men\u27s health behaviors and strategies for change. Methods: Qualitative interviews with 36 men (BMI 30 and over). Results: All men felt personally responsible for their weight gain. Sedentary lifestyles, stress, lack of worklife balance and weight-based stigma were all significant causes of weight gain and barriers to weight loss. These factors also contributed to men\u27s unwillingness to seek help for their overweight. Conclusion: Addressing the self-blame and stigma associated with obesity is important in developing strategies to improve the health and well-being of obese men
Update on the hadron spectrum with two flavors of staggered quarks
We present an update on the MILC Collaboration's light hadron spectrum
calculation with two flavors of dynamical, staggered quarks. We present
extrapolations of the nucleon to rho mass ratio to the continuum limit for
fixed values of the pi to rho mass ratio including the physical one.Comment: 3 pages, LaTex with espcrc2 and epsf, 5 postscript figures included,
Lattice '97 Proceeding
Heavy-light decay constants---MILC results with the Wilson action
We present the current status of our ongoing calculations of pseudoscalar
meson decay constants for mesons that contain one light and one heavy quark
(f_B, f_{B_s}, f_D, f_{D_s}). We are currently generating new gauge
configurations that include dynamical quarks and calculating the decay
constants. In addition, we have several new results for the static
approximation. Those results, as well as several refinements to the analysis,
are new since Lattice '96. Our current (still preliminary) value for f_B is 156
+- 11 +- 30 +- 14 MeV, where the first error is from statistical and fitting
errors, the second error is an estimate of other systematic errors within the
quenched approximation and the third error is an estimate of the quenching
error. For the ratio f_{B_s}/f_B, we get 1.11 +- 0.02 +- 0.03 +- 0.07.Comment: 8 pages, 9 figures, LaTeX, uses espcrs2, epsf, Invited talk presented
by S. Gottlieb at Lattice QCD on Parallel Computers, University of Tsukuba,
March, 1997, to appear in the proceeding
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