Auxin regulates SCFTIR1-dependent degradation of AUX/IAA proteins

The plant hormone auxin is central in many aspects of plant development. Previous studies have implicated the ubiquitin-ligase SCFTIR1 and the AUX/IAA proteins in auxin response. Dominant mutations in several AUX/IAA genes confer pleiotropic auxin-related phenotypes, whereas recessive mutations affecting the function of SCFTIR1 decrease auxin response. Here we show that SCFTIR1 is required for AUX/IAA degradation. We demonstrate that SCFTIR1 interacts with AXR2/IAA7 and AXR3/IAA17, and that domain II of these proteins is necessary and sufficient for this interaction. Further, auxin stimulates binding of SCFTIR1 to the AUX/IAA proteins, and their degradation. Because domain II is conserved in nearly all AUX/IAA proteins in Arabidopsis, we propose that auxin promotes the degradation of this large family of transcriptional regulators, leading to diverse downstream effects

An iterative joint codebook and classifier improvement algorithm for finite-state vector quantization

A finite-state vector quantizer (FSVQ) is a multicodebook system in, which the current state (or codebook) is chosen as a function of the previously quantized vectors. The authors introduce a novel iterative algorithm for joint codebook and next state function design of full search finite-state vector quantizers. They consider the fixed-rate case, for which no optimal design strategy is known. A locally optimal set of codebooks is designed for the training data and then predecessors to the training vectors associated with each codebook are appropriately labelled and used in designing the classifier. The algorithm iterates between next state function and state codebook design until it arrives at a suitable solution. The proposed design consistently yields better performance than the traditional FSVQ design method (under identical state space and codebook constraints)

Effects of digital approximation in statistical estimation Final technical report

Digital approximation in statistical estimatio

Forced-flow once-through boilers

A compilation and review of NASA-sponsored research on boilers for use in spacecraft electrical power generation systems is presented. Emphasis is on the heat-transfer and fluid-flow problems. In addition to space applications, much of the boiler technology is applicable to terrestrial and marine uses such as vehicular power, electrical power generation, vapor generation, and heating and cooling. Related research areas are discussed such as condensation, cavitation, line and boiler dynamics, the SNAP-8 project (Mercury-Rankine cycle), and conventional terrestrial boilers (either supercritical or gravity-assisted liquid-vapor separation types). The research effort was directed at developing the technology for once-through compact boilers with high heat fluxes to generate dry vapor stably, without utilizing gravity for phase separations. A background section that discusses, tutorially, the complex aspects of the boiling process is presented. Discussions of tests on alkali metals are interspersed with those on water and other fluids on a phenomenological basis

Analysis and acoustooptical measurements of bulk and surface acoustic wave fields

The development of multielement ultrasonic transducers having full field amplitude and phase control is discussed. In addition, the measurement of the surface particle displacement caused by an idealized impulse load on the surface, the three dimensional mapping of acoustic fields using optical scanning techniques, and the measurement of two dimensional stress distributions using embedded optical fiber sensors are addressed

Auxin-induced SCFTIR1-Aux/IAA interaction involves stable modification of the SCFTIR1 complex

The plant hormone auxin can regulate gene expression by destabilizing members of the Aux/IAA family of transcriptional repressors. Auxin-induced Aux/IAA degradation requires the protein-ubiquitin ligase SCFTIR1, with auxin acting to enhance the interaction between the Aux/IAAs and SCIFTIR1. SKP1, Cullin, and an F-box-containing protein (SCF)-mediated degradation is an important component of many eukaryotic signaling pathways. In all known cases to date, the interaction between the targets and their cognate SCFs is regulated by signal-induced modification of the target. The mechanism by which auxin promotes the interaction between SCFTIR1 and Aux/IAAs is not understood, but current hypotheses propose auxin-induced phosphorylation, hydroxylation, or proline isomerization of the Aux/IAAs. We found no evidence to support these hypotheses or indeed that auxin induces any stable modification of Aux/IAAs to increase their affinity for SCFTIR1. Instead, we present data suggesting that auxin promotes the SCIFTIR1-Aux/IAA interaction by affecting the SCIF component, TIR1, or proteins tightly associated with it

Stability of adversarial Markov chains, with an application to adaptive MCMC algorithms

We consider whether ergodic Markov chains with bounded step size remain bounded in probability when their transitions are modified by an adversary on a bounded subset. We provide counterexamples to show that the answer is no in general, and prove theorems to show that the answer is yes under various additional assumptions. We then use our results to prove convergence of various adaptive Markov chain Monte Carlo algorithms.Comment: Published at http://dx.doi.org/10.1214/14-AAP1083 in the Annals of Applied Probability (http://www.imstat.org/aap/) by the Institute of Mathematical Statistics (http://www.imstat.org

Bisectors of the HARPS Cross-Correlation-Function. The dependence on stellar atmospheric parameters

Bisectors of the HARPS cross-correlation function (CCF) can discern between planetary radial-velocity (RV) signals and spurious RV signals from stellar magnetic activity variations. However, little is known about the effects of the stellar atmosphere on CCF bisectors or how these effects vary with spectral type and luminosity class. Here we investigate the variations in the shapes of HARPS CCF bisectors across the HR diagram in order to relate these to the basic stellar parameters, surface gravity and temperature. We use archive spectra of 67 well studied stars observed with HARPS and extract mean CCF bisectors. We derive previously defined bisector measures (BIS, v_bot, c_b) and we define and derive a new measure called the CCF Bisector Span (CBS) from the minimum radius of curvature on direct fits to the CCF bisector. We show that the bisector measures correlate differently, and non-linearly with log g and T_eff. The resulting correlations allow for the estimation of log g and T_eff from the bisector measures. We compare our results with 3D stellar atmosphere models and show that we can reproduce the shape of the CCF bisector for the Sun.Comment: 13 pages, 20 figures. Accepted by A&