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  1. Rapid Assessment of Earthquake Source Characteristics

    Lui, Semechah K. Y.; Helmberger, Don; Yu, Junjie; Wei, Shengji
    Recent studies emphasize the rapid assessment of earthquake source properties, such as moment magnitude, to help alleviate the impact of earthquakes. Depending on local crustal structure, earthquakes occurring at different depths can differ greatly in high‐frequency motions, which emphasizes the importance in constraining focal depth for the predictions of strong motions. For large earthquakes, assessing rupture directivity is also essential in estimating ground‐motion effects throughout the source region. In this article, we perform an in‐depth study on a group of recent earthquakes near the intersection of the San Jacinto and San Andreas fault systems in southern California. We develop a...

  2. Modeling the organization of the WUSCHEL expression domain in the shoot apical meristem

    Jönsson, Henrik; Heisler, Marcus; Reddy, G. Venugopala; Agrawal, Vikas; Gor, Victoria; Shapiro, Bruce E.; Mjolsness, Eric; Meyerowitz, Elliot M.
    Motivation: The above-ground tissues of higher plants are generated from a small region of cells situated at the plant apex called the shoot apical meristem. An important genetic control circuit modulating the size of the Arabidopsis thaliana meristem is a feed-back network between the CLAVATA3 and WUSCHEL genes. Although the expression patterns for these genes do not overlap, WUSCHEL activity is both necessary and sufficient (when expressed ectopically) for the induction of CLAVATA3 expression. However, upregulation of CLAVATA3 in conjunction with the receptor kinase CLAVATA1 results in the downregulation of WUSCHEL. Despite much work, experimental data for this network are...

  3. Contrasting cloud composition between coupled and decoupled marine boundary layer clouds

    Wang, Zhen; Ramirez, Marco Mora; Dadashazar, Hossein; MacDonald, Alex B.; Crosbie, Ewan; Bates, Kelvin H.; Coggon, Matthew M.; Craven, Jill S.; Lynch, Peng; Campbell, James R.; Aghdam, Mojtaba Azadi; Woods, Roy K.; Jonsson, Haflidi; Flagan, Richard C.; Seinfeld, John H.; Sorooshian, Armin
    Marine stratocumulus clouds often become decoupled from the vertical layer immediately above the ocean surface. This study contrasts cloud chemical composition between coupled and decoupled marine stratocumulus clouds for dissolved nonwater substances. Cloud water and droplet residual particle composition were measured in clouds off the California coast during three airborne experiments in July–August of separate years (Eastern Pacific Emitted Aerosol Cloud Experiment 2011, Nucleation in California Experiment 2013, and Biological and Oceanic Atmospheric Study 2015). Decoupled clouds exhibited significantly lower air-equivalent mass concentrations in both cloud water and droplet residual particles, consistent with reduced cloud droplet number concentration and subcloud...

  4. Colour formation on the wings of the butterfly Hypolimnas salmacis by scale stacking

    Siddique, Radwanul Hasan; Vignolini, Silvia; Bartels, Carolin; Wacker, Irene; Hölscher, Hendrik
    The butterfly genus Hypolimnas features iridescent blue colouration in some areas of its dorsal wings. Here, we analyse the mechanisms responsible for such colouration on the dorsal wings of Hypolimnas salmacis and experimentally demonstrate that the lower thin lamina in the white cover scales causes the blue iridescence. This outcome contradicts other studies reporting that the radiant blue in Hypolimnas butterflies is caused by complex ridge-lamellar architectures in the upper lamina of the cover scales. Our comprehensive optical study supported by numerical calculation however shows that scale stacking primarily induces the observed colour appearance of Hypolimnas salmacis.

  5. The Dynamic Free Rider Problem: A Laboratory Study

    Battaglini, Marco; Nunnari, Salvatore; Palfrey, Thomas R.
    We report the results of an experiment that investigates free riding in the accumulation of durable public goods. We consider economies with reversibility, where contributions can be positive or negative; and economies with irreversibility, where contributions are nonnegative. Aggregate outcomes support the qualitative predictions of the Markov Perfect Equilibria (MPE) characterized in Battaglini, Nunnari, and Palfrey (2014): steady state levels of public good are lower with reversibility than irreversibility; accumulation is inefficiently slow; and the public good is under-provided in both regimes. On the other hand, public good levels are higher than MPE, and some evidence of history dependence is...

  6. Motion-corrected Fourier ptychography

    Bian, Liheng; Zheng, Guoan; Guo, Kaikai; Suo, Jinli; Yang, Changhuei; Chen, Feng; Dai, Qionghai
    Fourier ptychography (FP) is a recently proposed computational imaging technique for high space-bandwidth product imaging. In real setups such as endoscope and transmission electron microscope, the common sample motion largely degrades the FP reconstruction and limits its practicability. In this paper, we propose a novel FP reconstruction method to efficiently correct for unknown sample motion. Specifically, we adaptively update the sample’s Fourier spectrum from low spatial-frequency regions towards high spatial-frequency ones, with an additional motion recovery and phase-offset compensation procedure for each sub-spectrum. Benefiting from the phase retrieval redundancy theory, the required large overlap between adjacent sub-spectra offers an accurate...

  7. Analysis of Flow Timescales on a Periodically Pitching/Surging Airfoil

    Dunne, R.; Schmid, P. J.; McKeon, B. J.
    Time-resolved velocity fields around a pitching and surging NACA 0018 airfoil were analyzed to investigate the influence of three independent timescales associated with the unsteady flowfield. The first of these timescales, the period of the pitch/surge motion, is directly linked to the development of dynamic stall. A simplified model of the flow using only a time constant mode and the first two harmonics of the pitch surge frequency has been shown to accurately model the flow. Full stall and leading-edge flow separation, however, were found to take place before the maximum angle of attack, indicating that a different timescale was...

  8. Approximate sorting of data streams with limited storage

    Farnoud, Farzad; Yaakobi, Eitan; Bruck, Jehoshua
    We consider the problem of approximate sorting of a data stream (in one pass) with limited internal storage where the goal is not to rearrange data but to output a permutation that reflects the ordering of the elements of the data stream as closely as possible. Our main objective is to study the relationship between the quality of the sorting and the amount of available storage. To measure quality, we use permutation distortion metrics, namely the Kendall tau, Chebyshev, and weighted Kendall metrics, as well as mutual information, between the output permutation and the true ordering of data elements. We...

  9. Deep vs. shallow networks: An approximation theory perspective

    Mhaskar, Hrushikesh N.; Poggio, Tomaso
    The paper briefly reviews several recent results on hierarchical architectures for learning from examples, that may formally explain the conditions under which Deep Convolutional Neural Networks perform much better in function approximation problems than shallow, one-hidden layer architectures. The paper announces new results for a non-smooth activation function — the ReLU function — used in present-day neural networks, as well as for the Gaussian networks. We propose a new definition of relative dimension to encapsulate different notions of sparsity of a function class that can possibly be exploited by deep networks but not by shallow ones to drastically reduce the...

  10. Transitional annealed adaptive slice sampling for Gaussian process hyper-parameter estimation

    Garbuno-Inigo, Alfredo; DiazDelaO, F. A.; Zuev, Konstantin M.
    Surrogate models have become ubiquitous in science and engineering for their capability of emulating expensive computer codes, necessary to model and investigate complex phenomena. Bayesian emulators based on Gaussian processes adequately quantify the uncertainty that results from the cost of the original simulator, and thus the inability to evaluate it on the whole input space. However, it is common in the literature that only a partial Bayesian analysis is carried out, whereby the underlying hyper-parameters are estimated via gradient-free optimization or genetic algorithms, to name a few methods. On the other hand, maximum a posteriori (MAP) estimation could discard important...

  11. Benchmarking numerical models of brittle thrust wedges

    Buiter, Susanne J. H.; Schreurs, Guido; Albertz, Markus; Gerya, Taras V.; Kaus, Boris; Landry, Walter; le Pourhiet, Laetitia; Mishin, Yury; Egholm, David L.; Cooke, Michele; Maillot, Bertrand; Thieulot, Cedric; Crook, Tony; May, Dave; Souloumiac, Pauline; Beaumont, Christopher
    We report quantitative results from three brittle thrust wedge experiments, comparing numerical results directly with each other and with corresponding analogue results. We first test whether the participating codes reproduce predictions from analytical critical taper theory. Eleven codes pass the stable wedge test, showing negligible internal deformation and maintaining the initial surface slope upon horizontal translation over a frictional interface. Eight codes participated in the unstable wedge test that examines the evolution of a wedge by thrust formation from a subcritical state to the critical taper geometry. The critical taper is recovered, but the models show two deformation modes characterised...

  12. HANABA TARANU Is a GATA Transcription Factor That Regulates Shoot Apical Meristem and Flower Development in Arabidopsis

    Zhao, Yusnxiang; Medrano, Leonard; Ohashi, Kazuaki; Fletcher, Jennifer C.; Yu, Hao; Sakai, Hajime; Meyerowitz, Elliot M.
    We have isolated a new mutant, hanaba taranu (han), which affects both flower and shoot apical meristem (SAM) development in Arabidopsis thaliana. Mutants have fused sepals and reduced organ numbers in all four whorls, especially in the 2nd (petal) and 3rd (stamen) whorls. han meristems can become flatter or smaller than in the wild type. HAN encodes a GATA-3–like transcription factor with a single zinc finger domain. HAN is transcribed at the boundaries between the meristem and its newly initiated organ primordia and at the boundaries between different floral whorls. It is also expressed in vascular tissues, developing ovules and...

  13. Bloch wave buckling analysis of axially loaded periodic cylindrical shells

    Ning, Xin; Pellegrino, Sergio
    This paper presents an efficient computational method for predicting the onset of buckling of axially loaded, corrugated or stiffened cylindrical shells. This method is a modification of the Bloch wave method which builds on the stiffness matrix method. A numerical method and an efficient algorithm have been developed to implement the proposed method in the commercial finite element package Abaqus. Numerical examples have shown that, compared to the nonlinear buckling analyses based on detailed full finite element models, the proposed method can obtain highly accurate buckling loads and buckling modes and can achieve very significant reductions in computational time.

  14. Genome-Wide Analysis of Spatial Gene Expression in Arabidopsis Flowers

    Wellmer, Frank; Riechmann, José Luis; Alves-Ferreira, Márcio; Meyerowitz, Elliot M.
    We have compared the gene expression profiles of inflorescences of the floral homeotic mutants apetala1, apetala2, apetala3, pistillata, and agamous with that of wild-type plants using a flower-specific cDNA microarray and a whole genome oligonucleotide array. By combining the data sets from the individual mutant/wild type comparisons, we were able to identify a large number of genes that are, within flowers, predicted to be specifically or at least predominantly expressed in one type of floral organ. We have analyzed the expression patterns of several of these genes by in situ hybridization and found that they match the predictions that were...

  15. Two MscS Homologs Provide Mechanosensitive Channel Activities in the Arabidopsis Root

    Haswell, Elizabeth S.; Peyronnet, Rémi; Barbier-Brygoo, Hélène; Meyerowitz, Elliot M.; Frachisse, Jean-Marie
    In bacterial and animal systems, mechanosensitive (MS) ion channels are thought to mediate the perception of pressure, touch, and sound 1, 2 and 3. Although plants respond to a wide variety of mechanical stimuli, and although many mechanosensitive channel activities have been characterized in plant membranes by the patch-clamp method, the molecular nature of mechanoperception in plant systems has remained elusive [4]. Likely candidates are relatives of MscS (Mechanosensitive channel of small conductance), a well-characterized MS channel that serves to protect E. coli from osmotic shock [5]. Ten MscS-Like (MSL) proteins are found in the genome of the model flowering...

  16. A Repressor Complex Governs the Integration of Flowering Signals in Arabidopsis

    Li, Dan; Liu, Chang; Shen, Lisha; Wu, Yang; Chen, Hongyan; Robertson, Masumi; Helliwell, Chris A.; Ito, Toshiro; Meyerowitz, Elliot; Yu, Hao
    Multiple genetic pathways act in response to developmental cues and environmental signals to promote the floral transition, by regulating several floral pathway integrators. These include FLOWERING LOCUS T (FT) and SUPPRESSOR OF OVEREXPRESSION OF CONSTANS 1 (SOC1). We show that the flowering repressor SHORT VEGETATIVE PHASE (SVP) is controlled by the autonomous, thermosensory, and gibberellin pathways, and directly represses SOC1 transcription in the shoot apex and leaf. Moreover, FT expression in the leaf is also modulated by SVP. SVP protein associates with the promoter regions of SOC1 and FT, where another potent repressor FLOWERING LOCUS C (FLC) binds. SVP consistently...

  17. MscS-like Proteins Control Plastid Size and Shape in Arabidopsis thaliana

    Haswell, Elizabeth S.; Meyerowitz, Elliot M.
    Background Mechanosensitive (MS) ion channels provide a mechanism for the perception of mechanical stimuli such as sound, touch, and osmotic pressure. The bacterial MS ion channel MscS opens in response to increased membrane tension and serves to protect against cellular lysis during osmotic downshock. MscS-like proteins are found widely in bacterial and archaeal species and have also been identified in fission yeast and plants. None of the eukaryotic members of the family have yet been characterized. Results Here, we characterize two MscS-like (MSL) proteins from Arabidopsis thaliana, MSL2 and MSL3. MSL3 can rescue the osmotic-shock sensitivity of a bacterial mutant lacking MS-ion-channel activity,...

  18. Characterizing Truthfulness In Discrete Domains

    Mu'alem, Ahuva; Schapira, Michael
    Algorithmic mechanism design [9; 10] focuses on the design of algorithms that aim to achieve global objectives in settings in which the "input" is provided by self-interested strategic players2. This necessitates the design of algorithms that are incentive-compatible (a.k.a. truthful 3) in the sense that players are incentivized via payments to behave as instructed. The most natural approach to designing incentive-compatible algorithms is coming up with an algorithm and an explicit payment scheme that guarantees its incentive-compatibility. However, finding appropriate payments is often a difficult, setting-specific, task, which is mostly achievable for very simple types of algorithms.

  19. SPLAYED, a Novel SWI/SNF ATPase Homolog, Controls Reproductive Development in Arabidopsis

    Wagner, Doris; Meyerowitz, Elliot M.
    Background: The plant-specific transcriptional activator LEAFY (LFY) is a central regulator of the transition to reproductive development in Arabidopsis. LFY has a second, later role in the induction of floral homeotic gene expression. Available data suggests that, while LFY activity is controlled via interaction with tissue-specific coactivators, other mechanisms exist that regulate LFY activity, the identity of which are not known. Results: We have identified a novel component in the temporal control of the switch from vegetative to reproductive development in Arabidopsis thaliana. The SPLAYED (SYD) gene product acts with LFY to regulate shoot apical meristem identity. SYD is also involved...

  20. Architecture

    Messina, Paul; Culler, David; Pfeiffer, Wayne; Martin, William; Oden, J. Tinsley; Smith, Gary
    Uniting commodity processors by the thousands, emerging parallel architectures promise solutions to complex calculations—at least until the laws of physics impose a fundamental barrier to human innovation.

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