Survival and Growth of Two \u3ci\u3eHydraecia\u3c/i\u3e Species (Noctuidae: Lepidoptera) on Eight Midwest Grass Species

Grasses play a critical role in the life cycles of both the hop vine borer (Hydraecia immanis) and potato stem borer (H. micacea), two potentially se­rious agriculture pests. Neonate larvae of both species (Noctuidae: Lepidoptera) were reared on eight selected grasses and corn for 14-18 days under greenhouse conditions to determine their survival and growth. These were quackgrass (Agropyron repens), smooth bromegrass (Bromus inermis), orchardgrass (Dactylis glomerata), large crabgrass (Digitaria sanguinalis), barnyardgrass (Echinochloa crusgalli), giant foxtail (Seteria faberii), wild prosso millet (Panicum millaceum), Johnsongrass (Sorghum halepense), and corn (Zea mays). In a separate, concurrent experiment, H. immanis and H. micacea larvae were reared on quackgrass, smooth bromegrass and orchardgrass (narrow-stemmed grasses) and sampled after 7, 10 and 14 days. H. immanis larvae generally grew more slowly and dispersed less quickly than H. micacea larvae. The fewest H. immanis and H. micacea larvae were recovered from giant foxtail. H. immanis larvae reared on quackgrass, smooth bromegrass and orchardgrass (thin-stemmed grasses) outgrew their hosts by the third instar and rapidly dispersed, particularly from quackgrass. Due to the unique internal stem-feeding behavior of these larvae the stem thickness becomes a constraining factor regarding duration of suitability to serve as a larval host. Grass feeding has tremendous significance regarding the geographic spread, local population densities, phenological damage periods, and cultural control methods such as crop rotation for these two noctuid species

Small‐Molecule Photovoltaics Based on Functionalized Squaraine Donor Blends

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/91166/1/1956_ftp.pd

Accumulation of electric-field-stabilized geminate polaron pairs in an organic semiconductor to attain high excitation density under low intensity pumping

The recombination dynamics of geminate polaron pair (PP) states are investigated by monitoring electric-field-induced delayed fluorescence in thin films consisting of the green laser dye, Coumarin-6 (C6) doped at 1 wt %1wt% into 4,4′4,4′-bis(NN-carbazolyl)biphenyl. We find that the PP decay follows τ−mτ−m (with m ∼ 0.1m∼0.1), where ττ is the time that the PPs are held in the field. This sublinear decay suggests the possibility for accumulation of PPs over time that can then be reconverted into excitons upon field removal. We demonstrate the generation of short ( ∼ 50 ns∼50ns full width at half maximum) bursts of C6 fluorescence with peak intensities >20>20 times the steady-state fluorescence intensity (corresponding to a C6 singlet exciton density NS>4×1015 cm3NS>4×1015cm3) when pumped continuously by a low intensity (<1 W/cm2(<1W∕cm2) laser in the presence of a pulsed electric field.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87790/2/193502_1.pd

Insights into the Molecular Mechanism of Axon Outgrowth by Myelin Associated Inhibitors.

Repair after injury to the adult mammalian central nervous system (CNS) is hindered by inhibitory proteins, including the myelin associated inhibitors (MAIs): NogoA, MAG, and OMgp. Blocking the function of MAIs and their receptors enhances axon regrowth following injury. These findings suggest that therapeutic control of these inhibitors may be a strategy for regulating axon outgrowth and plasticity, leading to restoration of neuronal connections lost in response to injury or disease. Thus, functional recovery after CNS injury is limited by MAIs, and small molecule compounds that can circumvent MAI inhibition are likely to enhance functional recovery after stroke or spinal cord injury. The precise intracellular molecular signaling mechanisms of MAIs are not well understood. Toward this goal, it is demonstrated here that the multi-domain scaffold protein POSH assembles a distinct signaling module composed of the mixed-lineage kinase LZK, the actin-myosin regulatory protein Shroom3, and Rho-associated kinase, ROCK. Through the receptor PirB, the POSH complex mediates growth inhibitory signals from extracellular NogoA and MAG, as well as cell autonomous NogoA signaling. PirB associates with the protein tyrosine phosphatase, Shp2, and we show that phosphatase activity of Shp2 is required for axonal growth inhibition. In addition, NogoA stimulation promotes trapping of LZK with Shp2, suggesting LZK is a potential substrate for dephosphorylation by Shp2. Lastly, interference with the function of any member of the POSH complex results in enhanced growth on MAIs, suggesting that chemicals that target protein-protein interactions within the POSH complex will reduce the inhibitory action of MAIs, facilitating axon outgrowth in the CNS. Towards this goal, high-throughput screening in the Center for Chemical Genomics at the University of Michigan has identified potential inhibitors of the Shroom3-ROCK interaction. Collectively, these studies delineate an intracellular signaling pathway emanating from MAIs through the receptor PirB to the POSH complex. Further insight into the molecular signaling mechanisms of this pathway may provide novel therapeutic targets for axonal repair following CNS injury.PHDBiological ChemistryUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/93965/1/dicksonh_1.pd

Microscopic approach to pion-nucleus dynamics

Elastic scattering of pions from finite nuclei is investigated utilizing a contemporary, momentum--space first--order optical potential combined with microscopic estimates of second--order corrections. The calculation of the first--order potential includes:\ \ (1)~full Fermi--averaging integration including both the delta propagation and the intrinsic nonlocalities in the $\pi$-$N$ amplitude, (2)~fully covariant kinematics, (3)~use of invariant amplitudes which do not contain kinematic singularities, and (4)~a finite--range off--shell pion--nucleon model which contains the nucleon pole term. The effect of the delta--nucleus interaction is included via the mean spectral--energy approximation. It is demonstrated that this produces a convergent perturbation theory in which the Pauli corrections (here treated as a second--order term) cancel remarkably against the pion true absorption terms. Parameter--free results, including the delta--nucleus shell--model potential, Pauli corrections, pion true absorption, and short--range correlations are presented. (2 figures available from authors)Comment: 13 page

Frequency-dependent photoreactivity in disordered molecular polaritons

We present a powerful formalism (d-CUT-E) to simulate the ultrafast quantum dynamics of molecular polaritons in the collective strong coupling regime, where a disordered ensemble of $N\gg10^{6}$ molecules couples to a cavity mode. Notably, we can capture this dynamics with a cavity hosting a single $\textit{effective}$ molecule with $\sim N_{bins}$ electronic states, where $N_{bins}\ll N$ is the number of bins discretizing the disorder distribution. Using d-CUT-E, we show that in highly disordered ensembles, total reaction yield upon broadband excitation converges to that outside of the cavity. Yet, strong coupling can bestow different reactivities upon individual molecules, leading to changes in reaction yield upon narrowband excitation. Crucially, this effect goes beyond changes in linear absorption due to optical filtering through polaritons.Comment: 13 pages, 12 figure

Reliability of Small Molecule Organic Photovoltaics with Electron‐Filtering Compound Buffer Layers

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/134933/1/aenm201601094.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/134933/2/aenm201601094_am.pd