Swords and Plowshares

Cactus, chaos and caudillos: this awkwardly alliterative phrase unfortunately characterizes the views of many North Americans towards their neighbors south of the Rio Grande

Microbial Dehalogenation of Synthetic Organohalogen Compounds: Hydrolytic Dehalogenases

Hydrolytic removal of halogen substitutents is commonly the first step in the degradation of haloaliphatic compounds by aerobic bacteria, whereas initial dehalogenation of aryl halides is rare. Hydrolytic dehalogenations are catalyzed by specific dehalogenases, a group of enzymes which has been extensively studied in bacteria and which does not seem to occur in mammals. Questions pertaining to the origin and evolution of dehalogenases in soil bacteria have recently become tractable by the establishment of dehalogenase gene sequences. At the protein level, new dehalogenases are being discovered and known dehalogenases are being analyzed with respect to their mechanisms of catalysis. Finally, microbial dehalogenases, either as cells of dehalogenative bacteria or as enzyme preparations, have potential for applications in environmental biotechnology and biotransformation

Simulation of the daytime boundary layer evolution in deep mountain valleys

December, 1981.Bibliography: pages 96-100.Sponsored by the National Science Foundation ATM76-84405.Sponsored by the National Science Foundation ATM80-15309

Delta Self-Consistent Field as a method to obtain potential energy surfaces of excited molecules on surfaces

We present a modification of the $\Delta$SCF method of calculating energies of excited states, in order to make it applicable to resonance calculations of molecules adsorbed on metal surfaces, where the molecular orbitals are highly hybridized. The $\Delta$SCF approximation is a density functional method closely resembling standard density functional theory (DFT), the only difference being that in $\Delta$SCF one or more electrons are placed in higher lying Kohn-Sham orbitals, instead of placing all electrons in the lowest possible orbitals as one does when calculating the ground state energy within standard DFT. We extend the $\Delta$SCF method by allowing excited electrons to occupy orbitals which are linear combinations of Kohn-Sham orbitals. With this extra freedom it is possible to place charge locally on adsorbed molecules in the calculations, such that resonance energies can be estimated. The method is applied to N$_2$, CO and NO adsorbed on different metallic surfaces and compared to ordinary $\Delta$SCF without our modification, spatially constrained DFT and inverse-photoemission spectroscopy (IPES) measurements. This comparison shows that the modified $\Delta$SCF method gives results in close agreement with experiment, significantly closer than the comparable methods. For N$_2$ adsorbed on ruthenium (0001) we map out a 2-dimensional part of the potential energy surfaces in the ground state and the 2$\pi$-resonance. Finally we compare the $\Delta$SCF approach on gas-phase N$_2$ and CO, to higher accuracy methods. Excitation energies are approximated with accuracy close to that of time-dependent density functional theory, and we see very good agreement in the minimum shift of the potential energy surfaces in the excited state compared to the ground state.Comment: 11 pages, 7 figure

Multimodale Interaktion in Multi-Display-Umgebungen

Interaktive Umgebungen entwickeln sich mehr und mehr weg von Einzelarbeitsplätzen, hin zu Multi-Display-/Multi-User-Umgebungen. Diese stellen neue Anforderungen an Eingabegeräte und Interaktionstechniken. Im Rahmen dieser Arbeit werden neue Ansätze zur Interaktion auf Basis von Handgesten und Blick als neuartige Eingabemodalitäten entwickelt und untersucht

Multimodale Interaktion in Multi-Display-Umgebungen

Interaktive Umgebungen entwickeln sich mehr und mehr weg von Einzelarbeitsplätzen, hin zu Multi-Display-/Multi-User-Umgebungen. Diese stellen neue Anforderungen an Eingabegeräte und Interaktionstechniken. Im Rahmen dieser Arbeit werden neue Ansätze zur Interaktion auf Basis von Handgesten und Blick als neuartige Eingabemodalitäten entwickelt und untersucht

Discovering Behavioral Predispositions in Data to Improve Human Activity Recognition

The automatic, sensor-based assessment of challenging behavior of persons with dementia is an important task to support the selection of interventions. However, predicting behaviors like apathy and agitation is challenging due to the large inter- and intra-patient variability. Goal of this paper is to improve the recognition performance by making use of the observation that patients tend to show specific behaviors at certain times of the day or week. We propose to identify such segments of similar behavior via clustering the distributions of annotations of the time segments. All time segments within a cluster then consist of similar behaviors and thus indicate a behavioral predisposition (BPD). We utilize BPDs by training a classifier for each BPD. Empirically, we demonstrate that when the BPD per time segment is known, activity recognition performance can be substantially improved.Comment: Submitted to iWOAR 2022 - 7th international Workshop on Sensor-Based Activity Recognition and Artificial Intelligenc

Polarization and Charge Transfer in the Hydration of Chloride Ions

A theoretical study of the structural and electronic properties of the chloride ion and water molecules in the first hydration shell is presented. The calculations are performed on an ensemble of configurations obtained from molecular dynamics simulations of a single chloride ion in bulk water. The simulations utilize the polarizable AMOEBA force field for trajectory generation, and MP2-level calculations are performed to examine the electronic structure properties of the ions and surrounding waters in the external field of more distant waters. The ChelpG method is employed to explore the effective charges and dipoles on the chloride ions and first-shell waters. The Quantum Theory of Atoms in Molecules (QTAIM) is further utilized to examine charge transfer from the anion to surrounding water molecules. From the QTAIM analysis, 0.2 elementary charges are transferred from the ion to the first-shell water molecules. The default AMOEBA model overestimates the average dipole moment magnitude of the ion compared with the estimated quantum mechanical value. The average magnitude of the dipole moment of the water molecules in the first shell treated at the MP2 level, with the more distant waters handled with an AMOEBA effective charge model, is 2.67 D. This value is close to the AMOEBA result for first-shell waters (2.72 D) and is slightly reduced from the bulk AMOEBA value (2.78 D). The magnitude of the dipole moment of the water molecules in the first solvation shell is most strongly affected by the local water-water interactions and hydrogen bonds with the second solvation shell, rather than by interactions with the ion.Comment: Slight revision, in press at J. Chem. Phy