15,571 research outputs found

    Workshop on entrepreneurial finance: a summary

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    This Policy Discussion Paper summarizes papers that were presented at the Workshop on Entrepreneurial Finance, which was held March 12?13, 2009, at the Federal Reserve Bank of Cleveland. Researchers presented new empirical research that exploits data sets on entrepreneurial activity that are based on broad and representative data samples. Papers in the workshop focused primarily on analyses of the sources and structure of start-up finance, including the importance of bank lending, venture capital, angel investors, and owner equity.Small business - Finance

    How the Screw Is Turned: Henry James’s Amusette

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    Parrot as Paradigms: Infinite Deferral of Meaning in "Flaubert's Parrot"

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    Alien Registration- Scott, James B. (Benton, Kennebec County)

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    https://digitalmaine.com/alien_docs/18893/thumbnail.jp

    Differential localization of glutamate receptor subunits at the drosophila neuromuscular junction

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    The subunit composition of postsynaptic neurotransmitter receptors is a key determinant of synaptic physiology. Two glutamate receptor subunits, Drosophila glutamate receptor IIA (DGluRIIA) and DGluRIIB, are expressed at the Drosophila neuromuscular junction and are redundant for viability, yet differ in their physiological properties. We now identify a third glutamate receptor subunit at the Drosophila neuromuscular junction, DGluRIII, which is essential for viability. DGluRIII is required for the synaptic localization of DGluRIIA and DGluRIIB and for synaptic transmission. Either DGluRIIA or DGluRIIB, but not both, is required for the synaptic localization of DGluRIII. DGluRIIA and DGluRIIB compete with each other for access to DGluRIII and subsequent localization to the synapse. These results are consistent with a model of a multimeric receptor in which DGluRIII is an essential component. At single postsynaptic cells that receive innervation from multiple motoneurons, DGluRIII is abundant at all synapses. However, DGluRIIA and DGluRIIB are differentially localized at the postsynaptic density opposite distinct motoneurons. Hence, innervating motoneurons may regulate the subunit composition of their receptor fields within a shared postsynaptic cell. The capacity of presynaptic inputs to shape the subunit composition of postsynaptic receptors could be an important mechanism for synapse-specific regulation of synaptic function and plasticity

    Structural basis for sequence specific DNA binding and protein dimerization of HOXA13.

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    The homeobox gene (HOXA13) codes for a transcription factor protein that binds to AT-rich DNA sequences and controls expression of genes during embryonic morphogenesis. Here we present the NMR structure of HOXA13 homeodomain (A13DBD) bound to an 11-mer DNA duplex. A13DBD forms a dimer that binds to DNA with a dissociation constant of 7.5 nM. The A13DBD/DNA complex has a molar mass of 35 kDa consistent with two molecules of DNA bound at both ends of the A13DBD dimer. A13DBD contains an N-terminal arm (residues 324 - 329) that binds in the DNA minor groove, and a C-terminal helix (residues 362 - 382) that contacts the ATAA nucleotide sequence in the major groove. The N370 side-chain forms hydrogen bonds with the purine base of A5* (base paired with T5). Side-chain methyl groups of V373 form hydrophobic contacts with the pyrimidine methyl groups of T5, T6* and T7*, responsible for recognition of TAA in the DNA core. I366 makes similar methyl contacts with T3* and T4*. Mutants (I366A, N370A and V373G) all have decreased DNA binding and transcriptional activity. Exposed protein residues (R337, K343, and F344) make intermolecular contacts at the protein dimer interface. The mutation F344A weakens protein dimerization and lowers transcriptional activity by 76%. We conclude that the non-conserved residue, V373 is critical for structurally recognizing TAA in the major groove, and that HOXA13 dimerization is required to activate transcription of target genes

    Exploring a search for long-duration transient gravitational waves associated with magnetar bursts

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    Soft gamma repeaters and anomalous X-ray pulsars are thought to be magnetars, neutron stars with strong magnetic fields of order ∼1013\mathord{\sim} 10^{13}--1015 gauss10^{15} \, \mathrm{gauss}. These objects emit intermittent bursts of hard X-rays and soft gamma rays. Quasiperiodic oscillations in the X-ray tails of giant flares imply the existence of neutron star oscillation modes which could emit gravitational waves powered by the magnetar's magnetic energy reservoir. We describe a method to search for transient gravitational-wave signals associated with magnetar bursts with durations of 10s to 1000s of seconds. The sensitivity of this method is estimated by adding simulated waveforms to data from the sixth science run of Laser Interferometer Gravitational-wave Observatory (LIGO). We find a search sensitivity in terms of the root sum square strain amplitude of hrss=1.3Γ—10βˆ’21 Hzβˆ’1/2h_{\mathrm{rss}} = 1.3 \times 10^{-21} \, \mathrm{Hz}^{-1/2} for a half sine-Gaussian waveform with a central frequency f0=150 Hzf_0 = 150 \, \mathrm{Hz} and a characteristic time Ο„=400 s\tau = 400 \, \mathrm{s}. This corresponds to a gravitational wave energy of EGW=4.3Γ—1046 ergE_{\mathrm{GW}} = 4.3 \times 10^{46} \, \mathrm{erg}, the same order of magnitude as the 2004 giant flare which had an estimated electromagnetic energy of EEM=∼1.7Γ—1046(d/8.7 kpc)2 ergE_{\mathrm{EM}} = \mathord{\sim} 1.7 \times 10^{46} (d/ 8.7 \, \mathrm{kpc})^2 \, \mathrm{erg}, where dd is the distance to SGR 1806-20. We present an extrapolation of these results to Advanced LIGO, estimating a sensitivity to a gravitational wave energy of EGW=3.2Γ—1043 ergE_{\mathrm{GW}} = 3.2 \times 10^{43} \, \mathrm{erg} for a magnetar at a distance of 1.6 kpc1.6 \, \mathrm{kpc}. These results suggest this search method can probe significantly below the energy budgets for magnetar burst emission mechanisms such as crust cracking and hydrodynamic deformation
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