516 Delaware St Se Pwb Fourth Floor, Clinic 4A
Minneapolis MN 55455
Medical School: Other - Unknown
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License #: LP2163
Taxonomy Codes:103T00000X 103TM1800X
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Cyclohexadiene Revisited - a Time Resolved Photoelectron Spectroscopy and Ab Initio Study. - The journal of physical chemistry. A
We have studied the excited state dynamics of cyclohexa-1,3-diene (CHD) with time-resolved photoelectron spectroscopy and linear response time-dependent density functional theory fewest switches surface hopping after excitation to the lowest lying ï°ï°* (1B)-state. The combination of both theory and experiment revealed that the dynamics likely progress on a single excited state surface. After an incubation time of (35 Â± 10) fs on the excited state, the dynamics proceed to the ground state in an additional (60 Â± 10) fs, either via a conrotatory ring-opening to hexatriene or back to the cyclohexa-1,3-diene ground state. Ring-opening predominantly occurs when the wavepacket crosses the region of strong non-adiabatic coupling with a positive velocity in the bond alternation coordinate. After 100 fs, trajectories remaining in the excited state must return to the CHD ground state. This extra time-delay induces a revival of the photoelectron signal and is a direct proof that both channels are accessed. Moreover, our simulations suggest that the trans-Z isomer of hexatriene is formed directly upon ring-opening and that, after 1 ps, the thermodynamical equilibrium of three possible isomers is formed. Finally, we address the role of intermediate Rydberg resonances in the probe process of the experiment and their influence on the photoelectron spectra.
Analysis of human rotaviruses from a single location over an 18-year time span suggests that protein coadaption influences gene constellations. - Journal of virology
Rotaviruses (RVs) are 11-segmented, double-stranded RNA viruses that cause severe gastroenteritis in children. In addition to an error-prone genome replication mechanism, RVs can increase their genetic diversity by reassorting genes during host coinfection. Such exchanges allow RVs to acquire advantageous genes and adapt in the face of selective pressures. However, reassortment may also impose fitness costs if it unlinks genes/proteins that have accumulated compensatory, coadaptive mutations and that operate best when kept together. To better understand human RV evolutionary dynamics, we analyzed the genome sequences of 135 strains (genotype G1/G3/G4-P-I1-C1-R1-A1-N1-T1-E1-H1) that were collected at a single location in Washington, DC, during the years 1974 to 1991. Intragenotypic phylogenetic trees were constructed for each viral gene using the nucleotide sequences, thereby defining novel allele level gene constellations (GCs) and illuminating putative reassortment events. The results showed that RVs with distinct GCs cocirculated during the vast majority of the collection years and that some of these GCs persisted in the community unchanged by reassortment. To investigate the influence of protein coadaptation on GC maintenance, we performed a mutual information-based analysis of the concatenated amino acid sequences and identified an extensive covariance network. Unexpectedly, amino acid covariation was highest between VP4 and VP2, which are structural components of the RV virion that are not thought to directly interact. These results suggest that GCs may be influenced by the selective constraints placed on functionally coadapted, albeit noninteracting, viral proteins. This work raises important questions about mutation-reassortment interplay and its impact on human RV evolution.Rotaviruses are devastating human pathogens that cause severe diarrhea and kill >450,000 children each year. The virus can evolve by accumulating mutations and by acquiring new genes from other strains via a process called reassortment. However, little is known about the relationship between mutation accumulation and gene reassortment for rotaviruses and how it impacts viral evolution. In this study, we analyzed the genome sequences of human strains found in clinical fecal specimens that were collected at a single hospital over an 18-year time span. We found that many rotaviruses did not reassort their genes but instead maintained them as specific sets (i.e., constellations). By analyzing the encoded proteins, we discovered concurrent amino acid changes among them, which suggests that they are functionally coadapted to operate best when kept together. This study increases our understanding of how rotaviruses evolve over time in the human population.Copyright Â© 2014, American Society for Microbiology. All Rights Reserved.
Conversion efficiency of skutterudite-based thermoelectric modules. - Physical chemistry chemical physics : PCCP
Presently, the only commercially available power generating thermoelectric (TE) modules are based on bismuth telluride (Bi2Te3) alloys and are limited to a hot side temperature of 250 Â°C due to the melting point of the solder interconnects and/or generally poor power generation performance above this point. For the purposes of demonstrating a TE generator or TEG with higher temperature capability, we selected skutterudite based materials to carry forward with module fabrication because these materials have adequate TE performance and are mechanically robust. We have previously reported the electrical power output for a 32 couple skutterudite TE module, a module that is type identical to ones used in a high temperature capable TEG prototype. The purpose of this previous work was to establish the expected power output of the modules as a function of varying hot and cold side temperatures. Recent upgrades to the TE module measurement system built at the Fraunhofer Institute for Physical Measurement Techniques allow for the assessment of not only the power output, as previously described, but also the thermal to electrical energy conversion efficiency. Here we report the power output and conversion efficiency of a 32 couple, high temperature skutterudite module at varying applied loading pressures and with different interface materials between the module and the heat source and sink of the test system. We demonstrate a 7% conversion efficiency at the module level when a temperature difference of 460 Â°C is established. Extrapolated values indicate that 7.5% is achievable when proper thermal interfaces and loading pressures are used.
Joseph v. Brady: synthesis reunites what analysis has divided. - The Behavior analyst / MABA
Joseph V. Brady (1922-2011) created behavior-analytic neuroscience and the analytic framework for understanding how the external and internal neurobiological environments and mechanisms interact. Brady's approach offered synthesis as well as analysis. He embraced Findley's approach to constructing multioperant behavioral repertoires that found their way into designing environments for astronauts as well as studying drug effects on human social behavior in microenvironments. Brady created translational neurobehavioral science before such a concept existed. One of his most lasting contributions was developing a framework for ethical decision making to protect the rights of the people who participate in scientific research.
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515 Delaware St Se Cleft Palate Clinic - 6Th Floor Moos Tower
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