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Sample records for array finely tuned

  1. Hydrothermal growth of ZnO nanowire arrays: fine tuning by precursor supersaturation

    DOE PAGES

    Yan, Danhua; Cen, Jiajie; Zhang, Wenrui; ...

    2016-12-20

    In this paper, we develop a technique that fine tunes the hydrothermal growth of ZnO nanowires to address the difficulties in controlling their growth in a conventional one-pot hydrothermal method. In our technique, precursors are separately and slowly supplied with the assistance of a syringe pump, through the entire course of the growth. Compared to the one-pot method, the significantly lowered supersaturation of precursors helps eliminating competitive homogeneous nucleation and improves the reproducibility. The supersaturation degree can be readily tuned by the precursor quantity and injection rate, thus forming ZnO nanowire arrays of various geometries and packing densities in amore » highly controllable fashion. The precise control of ZnO nanowire growth enables systematic studies on the correlation between the material's properties and its morphology. Finally, in this work, ZnO nanowire arrays of various morphologies are studied as photoelectrochemical (PEC) water splitting photoanodes, in which we establish clear correlations between the water splitting performance and the nanowires' size, shape, and packing density.« less

  2. Hydrothermal growth of ZnO nanowire arrays: fine tuning by precursor supersaturation

    SciTech Connect

    Yan, Danhua; Cen, Jiajie; Zhang, Wenrui; Orlov, Alexander; Liu, Mingzhao

    2016-12-20

    In this paper, we develop a technique that fine tunes the hydrothermal growth of ZnO nanowires to address the difficulties in controlling their growth in a conventional one-pot hydrothermal method. In our technique, precursors are separately and slowly supplied with the assistance of a syringe pump, through the entire course of the growth. Compared to the one-pot method, the significantly lowered supersaturation of precursors helps eliminating competitive homogeneous nucleation and improves the reproducibility. The supersaturation degree can be readily tuned by the precursor quantity and injection rate, thus forming ZnO nanowire arrays of various geometries and packing densities in a highly controllable fashion. The precise control of ZnO nanowire growth enables systematic studies on the correlation between the material's properties and its morphology. Finally, in this work, ZnO nanowire arrays of various morphologies are studied as photoelectrochemical (PEC) water splitting photoanodes, in which we establish clear correlations between the water splitting performance and the nanowires' size, shape, and packing density.

  3. Automated Camera Array Fine Calibration

    NASA Technical Reports Server (NTRS)

    Clouse, Daniel; Padgett, Curtis; Ansar, Adnan; Cheng, Yang

    2008-01-01

    Using aerial imagery, the JPL FineCalibration (JPL FineCal) software automatically tunes a set of existing CAHVOR camera models for an array of cameras. The software finds matching features in the overlap region between images from adjacent cameras, and uses these features to refine the camera models. It is not necessary to take special imagery of a known target and no surveying is required. JPL FineCal was developed for use with an aerial, persistent surveillance platform.

  4. Tuned air gun array

    SciTech Connect

    Ruehle, W.H.

    1983-05-10

    The present invention provides a method for determining the spacing and size of air guns in a tuned air gun array. Volume ratios are calculated based upon a predetermined maximum volume for any individual air gun. The volumes are cross-referenced to spacings for optimum air gun interaction. The resulting air gun array operates as a broadband high-energy point source.

  5. Fine-tune the spectrum of indium-tin-oxide nanorod arrays in the visible range

    NASA Astrophysics Data System (ADS)

    Guo, Peijun; Diroll, Benjamin T.; Ketterson, John B.; Schaller, Richard D.; Chang, Robert P. H.

    2016-09-01

    All-optical modulation of light using metallic nanostructures can potentially enable processing of information with speed in the terahertz range. This is because the optical nonlinearity of metals dictated by the electron-phonon coupling is intrinsically fast. Nobel metals have achieved great success to this end due to their superior plasmonic properties in the visible. However, each type of noble metals only works in a specific wavelength range and therefore broadband spectral response covering the wide visible spectrum can be a challenge. Here we introduce indium-tin-oxide nanorod arrays (ITO-NRAs) which exhibit broadband response covering the visible spectrum. We show that the static spectral response of ITO-NRAs does not depend on the incident polarization and is insensitive to whether the lattice is a square or a rectangle. We further demonstrate that the transmission spectrum can be slightly shifted by changing the sample temperature, as well as adjusting the doping concentration which can be achieved by annealing the sample in oxygen rich environments. When pumped by an optical pulse with photon energy above the bandgap, the transmission can be modified in the entire visible range. These preliminary results show that ITONRAs offer unique opportunities for all-optical modulation in optical frequencies.

  6. Revisiting fine-tuning in the MSSM

    NASA Astrophysics Data System (ADS)

    Ross, Graham G.; Schmidt-Hoberg, Kai; Staub, Florian

    2017-03-01

    We evaluate the amount of fine-tuning in constrained versions of the minimal supersymmetric standard model (MSSM), with different boundary conditions at the GUT scale. Specifically we study the fully constrained version as well as the cases of non-universal Higgs and gaugino masses. We allow for the presence of additional non-holomorphic soft-terms which we show further relax the fine-tuning. Of particular importance is the possibility of a Higgsino mass term and we discuss possible origins for such a term in UV complete models. We point out that loop corrections typically lead to a reduction in the fine-tuning by a factor of about two compared to the estimate at tree-level, which has been overlooked in many recent works. Taking these loop corrections into account, we discuss the impact of current limits from SUSY searches and dark matter on the fine-tuning. Contrary to common lore, we find that the MSSM fine-tuning can be as small as 10 while remaining consistent with all experimental constraints. If, in addition, the dark matter abundance is fully explained by the neutralino LSP, the fine-tuning can still be as low as ˜ 20 in the presence of additional non-holomorphic soft-terms. We also discuss future prospects of these models and find that the MSSM will remain natural even in the case of a non-discovery in the foreseeable future.

  7. Understanding the Fine Tuning in Our Universe

    ERIC Educational Resources Information Center

    Cohen, Bernard L.

    2008-01-01

    It is often stated that the physical properties of our universe are "fine tuned"--that is, they must be almost exactly as they are to make the development of intelligent life possible. The implications of this statement, called the "anthropic principle," have been widely discussed in a philosophical context, but the scientific basis for the…

  8. Understanding the Fine Tuning in Our Universe

    ERIC Educational Resources Information Center

    Cohen, Bernard L.

    2008-01-01

    It is often stated that the physical properties of our universe are "fine tuned"--that is, they must be almost exactly as they are to make the development of intelligent life possible. The implications of this statement, called the "anthropic principle," have been widely discussed in a philosophical context, but the scientific basis for the…

  9. Fine-Tuning in a Design Experiment

    ERIC Educational Resources Information Center

    Ho, Foo Him; Toh, Pee Choon; Toh, Tin Lam

    2013-01-01

    Quek, Tay, Toh, Leong, and Dindyal (2011) proposed that a design-theory-practice troika should always be considered for a designed package to be acceptable to the research users who, in this case, are teachers and schools. This paper describes the fine-tuning to the MProSE problem-solving design made by the teachers in the school after first round…

  10. Fine-tuning in DBI inflationary mechanism

    SciTech Connect

    Chen, Xingang

    2008-12-15

    We show a model-independent fine-tuning issue in the DBI inflationary mechanism. DBI inflation requires a warp factor h small enough to sufficiently slow down the inflation. On the other hand, the Einstein equation in extra dimensions under the inflationary background deforms the warp space on the IR side. Generically these two locations coincide with each other, spoiling the DBI inflation. The origin and tuning of this 'h problem' is closely related, through the AdS/CFT duality, to those of the well-known '{eta} problem' in the slow-roll inflationary mechanism.

  11. Resistive Fine Tuning of Resonant Circuit

    NASA Technical Reports Server (NTRS)

    Mclyman, C. W.

    1985-01-01

    Simple fixed-inductance/fixed-capacitance tank circuit modified for fine adjustment of resonant frequency by addition of small inductance with potentiometer across it. Additional winding built into full winding as integral part or added externally. Technique provides quick way of tuning reactance out of power-transformer circuit to maximize power transfer or to adjust frequency of oscillator. Applications include rotary transformers, servo amplifiers, and analog computer modules.

  12. Multi-TeV Gamma-Ray Observation from the Crab Nebula Using the Tibet-III Air Shower Array Finely Tuned by the Cosmic Ray Moon's Shadow

    NASA Astrophysics Data System (ADS)

    Amenomori, M.; Bi, X. J.; Chen, D.; Cui, S. W.; Danzengluobu; Ding, L. K.; Ding, X. H.; Fan, C.; Feng, C. F.; Feng, Zhaoyang; Feng, Z. Y.; Gao, X. Y.; Geng, Q. X.; Guo, H. W.; He, H. H.; He, M.; Hibino, K.; Hotta, N.; Hu, Haibing; Hu, H. B.; Huang, J.; Huang, Q.; Jia, H. Y.; Kajino, F.; Kasahara, K.; Katayose, Y.; Kato, C.; Kawata, K.; Labaciren; Le, G. M.; Li, A. F.; Li, J. Y.; Lou, Y.-Q.; Lu, H.; Lu, S. L.; Meng, X. R.; Mizutani, K.; Mu, J.; Munakata, K.; Nagai, A.; Nanjo, H.; Nishizawa, M.; Ohnishi, M.; Ohta, I.; Onuma, H.; Ouchi, T.; Ozawa, S.; Ren, J. R.; Saito, T.; Saito, T. Y.; Sakata, M.; Sako, T. K.; Shibata, M.; Shiomi, A.; Shirai, T.; Sugimoto, H.; Takita, M.; Tan, Y. H.; Tateyama, N.; Torii, S.; Tsuchiya, H.; Udo, S.; Wang, B.; Wang, H.; Wang, X.; Wang, Y.; Wang, Y. G.; Wu, H. R.; Xue, L.; Yamamoto, Y.; Yan, C. T.; Yang, X. C.; Yasue, S.; Ye, Z. H.; Yu, G. C.; Yuan, A. F.; Yuda, T.; Zhang, H. M.; Zhang, J. L.; Zhang, N. J.; Zhang, X. Y.; Zhang, Y.; Zhang, Yi; Zhaxisangzhu; Zhou, X. X.

    2009-02-01

    The Tibet-III air shower array, consisting of 533 scintillation detectors, has been operating successfully at Yangbajing in Tibet, China since 1999. Using the data set collected by this array from 1999 November through 2005 November, we obtained the energy spectrum of γ-rays from the Crab Nebula, expressed by a power law as (dJ/dE) = (2.09 ± 0.32) × 10-12(E/3 TeV)-2.96±0.14 cm-2 s-1 TeV-1 in the energy range of 1.7-40 TeV. This result is consistent with other independent γ-ray observations by imaging air Cherenkov telescopes. In this paper, we carefully checked and tuned the performance of the Tibet-III array using data on the Moon's shadow in comparison with a detailed Monte Carlo (MC) simulation. The shadow is shifted to the west of the Moon's apparent position as an effect of the geomagnetic field, although the extent of this displacement depends on the primary energy of positively charged cosmic rays. This finding enables us to estimate the systematic error in determining the primary energy from its shower size. This error is estimated to be less than ±12% in our experiment. This energy scale estimation is the first attempt among cosmic ray experiments at ground level. The systematic pointing error is also estimated to be smaller than 0fdg011. The deficit rate and the position of the Moon's shadow are shown to be very stable within a statistical error of ±6% year by year. This guarantees the long-term stability of pointlike source observation with the Tibet-III array. These systematic errors are adequately taken into account in our study of the Crab Nebula.

  13. Pre - big bang inflation requires fine tuning

    SciTech Connect

    Turner, Michael S.; Weinberg, Erick J.

    1997-10-01

    The pre-big-bang cosmology inspired by superstring theories has been suggested as an alternative to slow-roll inflation. We analyze, in both the Jordan and Einstein frames, the effect of spatial curvature on this scenario and show that too much curvature --- of either sign --- reduces the duration of the inflationary era to such an extent that the flatness and horizon problems are not solved. Hence, a fine-tuning of initial conditions is required to obtain enough inflation to solve the cosmological problems.

  14. Nonsingular multidimensional cosmologies without fine tuning

    NASA Astrophysics Data System (ADS)

    Bronnikov, Kirill A.; Fabris, Julio C.

    2002-09-01

    Exact cosmological solutions for effective actions in D dimensions inspired by the tree-level superstring action are studied. For a certain range of free parameters existing in the model, nonsingular bouncing solutions are found. Among them, of particular interest can be open hyperbolic models, in which, without any fine tuning, the internal scale factor and the dilaton field (connected with string coupling in string theories) tend to constant values at late times. A cosmological singularity is avoided due to nonminimal dilaton-gravity coupling and, for D>11, due to pure imaginary nature of the dilaton, which conforms to currently discussed unification models. The existence of such and similar solutions supports the opinion that the Universe had never undergone a stage driven by full-scale quantum gravity.

  15. Fine tuning of cytosolic Ca 2+ oscillations

    PubMed Central

    Dupont, Geneviève; Combettes, Laurent

    2016-01-01

    Ca 2+ oscillations, a widespread mode of cell signaling, were reported in non-excitable cells for the first time more than 25 years ago. Their fundamental mechanism, based on the periodic Ca 2+ exchange between the endoplasmic reticulum and the cytoplasm, has been well characterized. However, how the kinetics of cytosolic Ca 2+ changes are related to the extent of a physiological response remains poorly understood. Here, we review data suggesting that the downstream targets of Ca 2+ are controlled not only by the frequency of Ca 2+ oscillations but also by the detailed characteristics of the oscillations, such as their duration, shape, or baseline level. Involvement of non-endoplasmic reticulum Ca 2+ stores, mainly mitochondria and the extracellular medium, participates in this fine tuning of Ca 2+ oscillations. The main characteristics of the Ca 2+ exchange fluxes with these compartments are also reviewed. PMID:27630768

  16. A cyclic universe approach to fine tuning

    DOE PAGES

    Alexander, Stephon; Cormack, Sam; Gleiser, Marcelo

    2016-04-05

    We present a closed bouncing universe model where the value of coupling constants is set by the dynamics of a ghost-like dilatonic scalar field. We show that adding a periodic potential for the scalar field leads to a cyclic Friedmann universe where the values of the couplings vary randomly from one cycle to the next. While the shuffling of values for the couplings happens during the bounce, within each cycle their time-dependence remains safely within present observational bounds for physically-motivated values of the model parameters. Our model presents an alternative to solutions of the fine tuning problem based on stringmore » landscape scenarios. (C) 2016 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). Funded by SCOAP(3).« less

  17. Approaching {lambda} without fine-tuning

    SciTech Connect

    Matarrese, Sabino; Baccigalupi, Carlo; Perrotta, Francesca

    2004-09-15

    We address the fine-tuning problem of dark energy cosmologies which arises when the dark energy density needs to initially lie in a narrow range in order for its present value to be consistent with observations. As recently noticed, this problem becomes particularly severe in canonical quintessence scenarios, when trying to reproduce the behavior of a cosmological constant, i.e., when the dark energy equation of state w{sub Q} approaches -1: these models may be reconciled with a large basin of attraction only by requiring a rapid evolution of w{sub Q} at low redshifts, which is in conflict with the most recent estimates from type Ia Supernovae discovered by Hubble space telescope. Next, we focus on scalar-tensor theories of gravity, discussing the implications of a coupling between the quintessence scalar field and the Ricci scalar ('extended quintessence'). We show that, even if the equation of state today is very close to -1, by virtue of the scalar-tensor coupling the quintessence trajectories still possess the attractive feature which allows to reach the present level of cosmic acceleration starting by a set of initial conditions which covers tens of orders of magnitude; this effect, entirely of gravitational origin, represents a new important consequence of the possible coupling between dark energy and gravity. We illustrate this effect in typical extended quintessence scenarios.

  18. Fine tuning of activity for nanoscale catalysts.

    SciTech Connect

    Strmcnik, D.; van derVliet, D.; Lucas, C.; Karapetrov, G.; Markovic, N.; Stamenkovic, V.; Materials Science Division

    2008-01-01

    similar levels of catalytic enhancement have been established for corresponding nanoscale materials. In addition to electronic properties we have found how catalytic activity could be affected by the arrangement of surface defects on nanoscale surfaces. Ability to control surface and near surface catalyst properties enables fine tuning of catalytic activity and stability of nanoscale surfaces.

  19. Fine tunings for inflation with simple potentials

    NASA Astrophysics Data System (ADS)

    Izawa, K.-I.

    2014-11-01

    We continue to investigate possible parameter choices for primordial inflation with simple potentials such as power-law and two-term potentials. We examine the amount of parameter tuning required to make the slow-roll inflation eternal. In particular, we adopt the critical coupling for marginally eternal inflation and see whether realistic primordial inflation is attainable under such a parameter choice. It turns out that potentials with mass scale of grand unification provide, after tuning, consistent results with experimental data so that the considered tuning is allowed observationally. Namely, the primordial inflation is possibly marginal in such a setup.

  20. Fine-Tuning Your Ensemble's Jazz Style.

    ERIC Educational Resources Information Center

    Garcia, Antonio J.

    1991-01-01

    Proposes instructional strategies for directors of jazz groups, including guidelines for developing of skills necessary for good performance. Includes effective methods for positive changes in ensemble style. Addresses jazz group problems such as beat, tempo, staying in tune, wind power, and solo/ensemble lines. Discusses percussionists, bassists,…

  1. The Doctoral Comprehensive Examination: Fine-Tuning the Process.

    ERIC Educational Resources Information Center

    Loughead, Teri Olisky

    1997-01-01

    Uses Bloom's Taxonomy of Educational Objectives to fine-tune the process of designing, preparing for, evaluating, and providing feedback about the doctoral comprehensive examination. Examines the purpose and objectives of comprehensive examinations, curriculum design, preparation for the exam, test item development, evaluation criteria, and…

  2. Why Cosmic Fine-Tuning Needs to BE Explained

    NASA Astrophysics Data System (ADS)

    Manson, Neil Alan

    Discoveries in modern physics and Big Bang cosmology indicate that if either the initial conditions of the universe or the physical laws governing its development had differed even slightly, life could never have developed. It is for this reason that the universe is said to be ``fine-tuned'' for life. I argue that cosmic fine-tuning, which some want to dismiss as the way things just happen to be, in fact needs to be explained. In Chapter One I provide an overview of the evidence that the universe is fine-tuned for life. In Chapter Two I present a set of sufficient conditions for a fact's needing to be explained. The conditions are that the fact is improbable and that a ``tidy'' explanation of it is available. A tidy explanation of a fact is considerably less improbable than that fact and makes the obtaining of that fact considerably less improbable. Chapters Three, Four, and Five are devoted to showing that cosmic Chapter Three I argue that the universe's being finely tuned for life can meaningfully be considered improbable. In Chapter Four I claim that there is at least one tidy explanation of cosmic fine-tuning: that the universe was created by some sort of extramundane designer. In Chapters Four and Five I respond to three objections. The first is that the design hypothesis is ad hoc. The second is that we have no reason to believe a supernatural designer would prefer life-permitting cosmoi to other possible cosmoi and that our tendency to believe otherwise is the result of anthropocentrism. The third is that the design hypothesis never buys us an explanatory advantage.

  3. The Fine-Tuning of the Universe for Intelligent Life

    NASA Astrophysics Data System (ADS)

    Barnes, L. A.

    2012-06-01

    The fine-tuning of the universe for intelligent life has received a great deal of attention in recent years, both in the philosophical and scientific literature. The claim is that in the space of possible physical laws, parameters and initial conditions, the set that permits the evolution of intelligent life is very small. I present here a review of the scientific literature, outlining cases of fine-tuning in the classic works of Carter, Carr and Rees, and Barrow and Tipler, as well as more recent work. To sharpen the discussion, the role of the antagonist will be played by Victor Stenger's recent book The Fallacy of Fine-Tuning: Why the Universe is Not Designed for Us. Stenger claims that all known fine-tuning cases can be explained without the need for a multiverse. Many of Stenger's claims will be found to be highly problematic. We will touch on such issues as the logical necessity of the laws of nature; objectivity, invariance and symmetry; theoretical physics and possible universes; entropy in cosmology; cosmic inflation and initial conditions; galaxy formation; the cosmological constant; stars and their formation; the properties of elementary particles and their effect on chemistry and the macroscopic world; the origin of mass; grand unified theories; and the dimensionality of space and time. I also provide an assessment of the multiverse, noting the significant challenges that it must face. I do not attempt to defend any conclusion based on the fine-tuning of the universe for intelligent life. This paper can be viewed as a critique of Stenger's book, or read independently.

  4. Fine tuning and MOND in a metamaterial "multiverse".

    PubMed

    Smolyaninov, Igor I; Smolyaninova, Vera N

    2017-08-14

    We consider the recently suggested model of a multiverse based on a ferrofluid. When the ferrofluid is subjected to a modest external magnetic field, the nanoparticles inside the ferrofluid form small hyperbolic metamaterial domains, which from the electromagnetic standpoint behave as individual "Minkowski universes" exhibiting different "laws of physics", such as different strength of effective gravity, different versions of modified Newtonian dynamics (MOND) and different radiation lifetimes. When the ferrofluid "multiverse" is populated with atomic or molecular species, and these species are excited using an external laser source, the radiation lifetimes of atoms and molecules in these "universes" depend strongly on the individual physical properties of each "universe" via the Purcell effect. Some "universes" are better fine-tuned than others to sustain the excited states of these species. Thus, the ferrofluid-based metamaterial "multiverse" may be used to study models of MOND and to illustrate the fine-tuning mechanism in cosmology.

  5. Stop search with acceptable fine-tuning in Susy models

    NASA Astrophysics Data System (ADS)

    Ćiçi, Ali; Ün, Cem Salih; Kirca, Zerrin

    2017-02-01

    Supersymmetry (SUSY) is one of the forefront candidates for the models beyond the Standard Model (SM) in resolving the gauge hierarchy problem by proposing new supersymmetric partners for the SM fields. In SUSY, stop, the supersymmetric partner of top quark, is of a special importance, since it cancels the largest quadratic contributions to the Higgs boson mass from top quark loop. Despite heavy stop mass requirement from the Higgs boson searches and fine-tuning demands, it is still possible to find stops of mass about a few hundred GeV, even as light as top quark. In this study, we search for light stop solutions within the SUSY Grand Unified Theory (GUT) models in light of acceptable fine-tuning and current experimental constraints. Afterwards, we analyze the possible signals through which the implications can be tested at the Large Hadron Collider (LHC) experiments.

  6. Cosmologically Safe QCD Axion without Fine-Tuning

    NASA Astrophysics Data System (ADS)

    Yamada, Masaki; Yanagida, Tsutomu T.; Yonekura, Kazuya

    2016-02-01

    Although QCD axion models are widely studied as solutions to the strong C P problem, they generically confront severe fine-tuning problems to guarantee the anomalous Peccei-Quinn (PQ) symmetry. In this Letter, we propose a simple QCD axion model without any fine-tunings. We introduce an extra dimension and a pair of extra quarks living on two branes separately, which is also charged under a bulk Abelian gauge symmetry. We assume a monopole condensation on our brane at an intermediate scale, which implies that the extra quarks develop chiral symmetry breaking and the PQ symmetry is broken. In contrast to Kim's original model, our model explains the origin of the PQ symmetry thanks to the extra dimension and avoids the cosmological domain wall problem because of chiral symmetry breaking in Abelian gauge theory.

  7. Cosmologically Safe QCD Axion without Fine-Tuning.

    PubMed

    Yamada, Masaki; Yanagida, Tsutomu T; Yonekura, Kazuya

    2016-02-05

    Although QCD axion models are widely studied as solutions to the strong CP problem, they generically confront severe fine-tuning problems to guarantee the anomalous Peccei-Quinn (PQ) symmetry. In this Letter, we propose a simple QCD axion model without any fine-tunings. We introduce an extra dimension and a pair of extra quarks living on two branes separately, which is also charged under a bulk Abelian gauge symmetry. We assume a monopole condensation on our brane at an intermediate scale, which implies that the extra quarks develop chiral symmetry breaking and the PQ symmetry is broken. In contrast to Kim's original model, our model explains the origin of the PQ symmetry thanks to the extra dimension and avoids the cosmological domain wall problem because of chiral symmetry breaking in Abelian gauge theory.

  8. Low fine-tuning in Yukawa-deflected gauge mediation

    NASA Astrophysics Data System (ADS)

    Ahmed, Waqas; Calibbi, Lorenzo; Li, Tianjun; Mustafayev, Azar; Raza, Shabbar

    2017-05-01

    We discuss a class of models with gauge-mediated supersymmetry-breaking characterized by a nonunified messenger sector inducing nonstandard gaugino mass ratios, as well as by additional contributions to the soft mass terms from a matter-messenger coupling. The well-known effect of this coupling is to generate A-terms at one-loop level, hence raising the Higgs mass without relying on superheavy stops. At the same time, a hierarchy between Wino and gluino masses, as induced by the nonunified messenger fields, can greatly lower the radiative corrections to the Higgs soft mass term driven by the high-energy parameters, thus reducing the fine-tuning. We search for models with low fine-tuning within this scenario, and we discuss the spectrum, collider phenomenology, constraints, and prospects of the found solutions. We find that some setups are accessible or already excluded by searches at the Large Hadron Collider, and all our scenarios with a tuning better than about 2% can be tested at the International Linear Collider.

  9. Towards understanding fine-tuning in fundamental physics

    NASA Astrophysics Data System (ADS)

    Larsen, Grant Edward

    The standard models of particle physics and cosmology are enjoying wild success, but are beset by surprising features. Chief among these are the mysterious smallness of general relativity's cosmological constant (known as the cosmological constant "problem"), and the mysteriously tremendous strength of all other forces relative to gravity (known as the hierarchy "problem"). Both are instances of a physically relevant quantity that (due to quantum effects) is a sum of many (unknown) quantities; in both cases, these summands seem to cancel out to remarkable precision to give a much smaller sum, a phenomenon called fine-tuning. The size of the cosmological constant has proved robust against explanation on the grounds of physical principles like symmetry. Such explanations of the electroweak/gravity hierarchy abound, but recent experimental efforts have ruled many of them out, or forced them to introduce new fine-tuning. In both cases, arguments about selection effects and priors have emerged. Here, a dialectic approach is taken to understanding this apparent fine-tuning in nature: First, symmetry is employed. Supersymmetry famously resolves the hierarchy problem, but is under siege by increasing experimental constraints ruling out much of its natural parameter space. A class of supersymmetry models with supersymmetry broken at a low scale is proposed which evade experimental constraints without needing fine-tuning. The key ingredient is some anti-correlation between supersymmetry-breaking effects and electroweak-breaking effects on a field, e.g. if the symmetry-breaking fields are localized at different points along an extra dimension. Then, a careful argument employing selection effects and Bayesian reasoning is undertaken to show that the size of the cosmological constant is not surprising. Previous such arguments have suggested many different probability measures on the space of different possibilities, but a careful review of quantum mechanics shows a unique

  10. Phased waveguide array with fixed tuning elements

    SciTech Connect

    Motley, R.W.; Bernabei, S.; Hooke, W.M.; Paoloni, F.J.

    1980-04-01

    The waveguide grill excites both penetrating lower hybrid waves and surface plasma waves. Quarter wavelength tuning elements attached to the sides of a twin waveguide are shown to reduce the surface wave component by a factor of approx. 3..

  11. Modern Cosmology and Anthropic Fine-Tuning: Three approaches

    NASA Astrophysics Data System (ADS)

    Collins, Robin

    The anthropic fine-tuning of the cosmos refers to the claim that the laws of nature, the constants of physics, and the initial conditions of the universe must be set to an enormous degree of precision for embodied conscious agents to exist. Three major responses have been offered to this fine-tuning: the multiverse explanation; theism; and the claim that it is just a brute fact that requires no further explanation. In this chapter, I will consider each explanation in turn, and provide some novel arguments for the superiority of a theistic or related explanation. In the last section, I will show how whether or not one adopts a theistic or related explanation can significantly influence what features of the universe one considers in need of further scientific explanation, and the type of scientific explanation that one should find satisfactory. In particular, I will argue that in some cases atheism, not theism, serves as a science stopper in discouraging a search for deeper scientific explanations of phenomena.

  12. Hearing aid fine-tuning based on Dutch descriptions.

    PubMed

    Thielemans, Thijs; Pans, Donné; Chenault, Michelene; Anteunis, Lucien

    2017-07-01

    The aim of this study was to derive an independent fitting assistant based on expert consensus. Two questions were asked: (1) what (Dutch) terms do hearing impaired listeners use nowadays to describe their specific hearing aid fitting problems? (2) What is the expert consensus on how to resolve these complaints by adjusting hearing aid parameters? Hearing aid dispensers provided descriptors that impaired listeners use to describe their reactions to specific hearing aid fitting problems. Hearing aid fitting experts were asked "How would you adjust the hearing aid if its user reports that the aid sounds…?" with the blank filled with each of the 40 most frequently mentioned descriptors. 112 hearing aid dispensers and 15 hearing aid experts. The expert solution with the highest weight value was considered the best solution for that descriptor. Principal component analysis (PCA) was performed to identify a factor structure in fitting problems. Nine fitting problems could be identified resulting in an expert-based, hearing aid manufacturer independent, fine-tuning fitting assistant for clinical use. The construction of an expert-based, hearing aid manufacturer independent, fine-tuning fitting assistant to be used as an additional tool in the iterative fitting process is feasible.

  13. Coarse-fine adaptive tuned vibration absorber with high frequency resolution

    NASA Astrophysics Data System (ADS)

    Wang, Xi; Yang, Bintang; You, Jiaxin; Gao, Zhe

    2016-11-01

    The speed fluctuation of satellite-rotary-mechanisms causes vibration of slightly different frequencies. The critical requirements of satellites need a vibration control device with high frequency resolution to suppress the vibration. This paper presents a coarse-fine adaptive tuned vibration absorber (ATVA) with high frequency resolution. The coarse-fine ATVA which simultaneously satisfies the requirements of high resolution and relatively wide effective bandwidth is capable of tracking the variable exciting frequency adaptively to suppress the vibration of the primary system. The coarse-fine ATVA is divided into a coarse tuning segment and a fine tuning segment. The coarse tuning segment is used to tune the required natural frequency in a relatively wide effective bandwidth and the fine tuning segment can achieve precise tune in a tiny-scale bandwidth. The mathematical model of the coarse tuning and the fine tuning is proposed to design the parameters of the coarse-fine ATVA. The experimental test results indicate the coarse tuning bandwidth of the coarse-fine ATVA is 8.7 Hz to 29 Hz and the minimum resolution of the fine tuning is 0.05 Hz. Moreover, a significant vibration attenuation of 15dB is verified in the effective bandwidth.

  14. Phase lock acquisition system having FLL for coarse tuning and PLL for fine tuning

    NASA Astrophysics Data System (ADS)

    Caldwell, S. P.; Decker, M. J.; Jelen, R. A.

    1986-04-01

    The acquisition of phase lock to a reference frequency by a signal acquisition system is accomplished using a voltage controlled oscillator, a wideband frequency discriminator, a prepositioning circuit, and a phase lock loop. The voltage controlled oscillator is prepositioned within a loop bandwidth of the reference frequency by the prepositioning circuit and the wide band frequency discriminator which provide coarse tuning. The voltage controlled oscillator achieves phase lock with the reference frequency when it receives the fine tune signal from the phase lock loop. Using both the discriminator and the phase lock loop allows fast acquisition without the need to calibrate the voltage controlled oscillator. Since the discriminator pull-in range is much larger than the phase-lock loop bandwidth, the number of bits can be much smaller than in acquisition circuit using a digital prepositioning circuit alone.

  15. Relaxion cosmology and the price of fine-tuning

    NASA Astrophysics Data System (ADS)

    Di Chiara, Stefano; Kannike, Kristjan; Marzola, Luca; Racioppi, Antonio; Raidal, Martti; Spethmann, Christian

    2016-05-01

    The relaxion scenario presents an intriguing extension of the standard model in which the particle introduced to solve to the strong C P problem, the axion, also achieves the dynamical relaxation of the Higgs boson mass term. In this work we complete this framework by proposing a scenario of inflationary cosmology that is consistent with all the observational constraints: the relaxion hybrid inflation with an asymmetric waterfall. In our scheme, the vacuum energy of the inflaton drives inflation in a natural way while the relaxion slow rolls. The constraints on the present inflationary observables are then matched through a subsequent inflationary epoch driven by the inflaton. We quantify the amount of fine-tuning of the proposed inflation scenario, concluding that the inflaton sector severely decreases the naturalness of the theory.

  16. Fine-tuning tomato agronomic properties by computational genome redesign.

    PubMed

    Carrera, Javier; Fernández Del Carmen, Asun; Fernández-Muñoz, Rafael; Rambla, Jose Luis; Pons, Clara; Jaramillo, Alfonso; Elena, Santiago F; Granell, Antonio

    2012-01-01

    Considering cells as biofactories, we aimed to optimize its internal processes by using the same engineering principles that large industries are implementing nowadays: lean manufacturing. We have applied reverse engineering computational methods to transcriptomic, metabolomic and phenomic data obtained from a collection of tomato recombinant inbreed lines to formulate a kinetic and constraint-based model that efficiently describes the cellular metabolism from expression of a minimal core of genes. Based on predicted metabolic profiles, a close association with agronomic and organoleptic properties of the ripe fruit was revealed with high statistical confidence. Inspired in a synthetic biology approach, the model was used for exploring the landscape of all possible local transcriptional changes with the aim of engineering tomato fruits with fine-tuned biotechnological properties. The method was validated by the ability of the proposed genomes, engineered for modified desired agronomic traits, to recapitulate experimental correlations between associated metabolites.

  17. Fine-Tuning Tomato Agronomic Properties by Computational Genome Redesign

    PubMed Central

    Carrera, Javier; Fernández del Carmen, Asun; Fernández-Muñoz, Rafael; Rambla, Jose Luis; Pons, Clara; Jaramillo, Alfonso; Elena, Santiago F.; Granell, Antonio

    2012-01-01

    Considering cells as biofactories, we aimed to optimize its internal processes by using the same engineering principles that large industries are implementing nowadays: lean manufacturing. We have applied reverse engineering computational methods to transcriptomic, metabolomic and phenomic data obtained from a collection of tomato recombinant inbreed lines to formulate a kinetic and constraint-based model that efficiently describes the cellular metabolism from expression of a minimal core of genes. Based on predicted metabolic profiles, a close association with agronomic and organoleptic properties of the ripe fruit was revealed with high statistical confidence. Inspired in a synthetic biology approach, the model was used for exploring the landscape of all possible local transcriptional changes with the aim of engineering tomato fruits with fine-tuned biotechnological properties. The method was validated by the ability of the proposed genomes, engineered for modified desired agronomic traits, to recapitulate experimental correlations between associated metabolites. PMID:22685389

  18. Fine-tuning challenges for the matter bounce scenario

    NASA Astrophysics Data System (ADS)

    Levy, Aaron M.

    2017-01-01

    A bouncing universe with a long period of contraction during which the average density is pressureless (the same equation of state as matter) as cosmologically observable scales exit the Hubble horizon has been proposed as an explanation for producing a nearly scale-invariant spectrum of adiabatic scalar perturbations. A well-known problem with this scenario is that, unless suppressed, the energy density associated with anisotropy grows to dominate that of the pressureless matter, so the matter-like phase is unstable. Previous models introduced an ekpyrotic phase after the matter-like phase to prevent the anisotropy from generating chaotic mixmaster behavior. In this work, though, we point out that, unless the anisotropy is suppressed first, the matter-like phase will never start and that suppressing the anisotropy requires extraordinary, exponential fine-tuning.

  19. Myosin phosphatase Fine-tunes Zebrafish Motoneuron Position during Axonogenesis

    PubMed Central

    Granato, Michael

    2016-01-01

    During embryogenesis the spinal cord shifts position along the anterior-posterior axis relative to adjacent tissues. How motor neurons whose cell bodies are located in the spinal cord while their axons reside in adjacent tissues compensate for such tissue shift is not well understood. Using live cell imaging in zebrafish, we show that as motor axons exit from the spinal cord and extend through extracellular matrix produced by adjacent notochord cells, these cells shift several cell diameters caudally. Despite this pronounced shift, individual motoneuron cell bodies stay aligned with their extending axons. We find that this alignment requires myosin phosphatase activity within motoneurons, and that mutations in the myosin phosphatase subunit mypt1 increase myosin phosphorylation causing a displacement between motoneuron cell bodies and their axons. Thus, we demonstrate that spinal motoneurons fine-tune their position during axonogenesis and we identify the myosin II regulatory network as a key regulator. PMID:27855159

  20. Pentagone internalises glypicans to fine-tune multiple signalling pathways

    PubMed Central

    Norman, Mark; Vuilleumier, Robin; Springhorn, Alexander; Gawlik, Jennifer; Pyrowolakis, George

    2016-01-01

    Tight regulation of signalling activity is crucial for proper tissue patterning and growth. Here we investigate the function of Pentagone (Pent), a secreted protein that acts in a regulatory feedback during establishment and maintenance of BMP/Dpp morphogen signalling during Drosophila wing development. We show that Pent internalises the Dpp co-receptors, the glypicans Dally and Dally-like protein (Dlp), and propose that this internalisation is important in the establishment of a long range Dpp gradient. Pent-induced endocytosis and degradation of glypicans requires dynamin- and Rab5, but not clathrin or active BMP signalling. Thus, Pent modifies the ability of cells to trap and transduce BMP by fine-tuning the levels of the BMP reception system at the plasma membrane. In addition, and in accordance with the role of glypicans in multiple signalling pathways, we establish a requirement of Pent for Wg signalling. Our data propose a novel mechanism by which morphogen signalling is regulated. DOI: http://dx.doi.org/10.7554/eLife.13301.001 PMID:27269283

  1. Fine tuning points of generating function construction for linear recursions

    NASA Astrophysics Data System (ADS)

    Yolcu, Bahar; Demiralp, Metin

    2014-10-01

    Recursions are quite important mathematical tools since many systems are mathematically modelled to ultimately take us to these equations because of their rather easy algebraic natures. They fit computer programming needs quite well in many circumstances to produce solutions. However, it is generally desired to find the asymptotic behaviour of the general term in the relevant sequence for convergence and therefore practicality issues. One of the general tendencies to find the general term asymptotic behaviour, when its ordering number grows unboundedly, is the integral representation over a generating function which does not depend on individual sequence elements. This is tried to be done almost for all types of recursions, even though the linear cases gain more importance than the others because they can be more effectively investigated by using many linear algebraic tools. Despite this may seem somehow to be rather trivial, there are a lot of theoretical fine tuning issues in the construction of true integral representations over true intervals on real axis or paths in complex domains. This work is devoted to focus on this issue starting from scratch for better understanding of the matter. The example cases are chosen to best illuminate the situations to get information for future generalization even though the work can be considered at somehow introductory level.

  2. ''Fine tuning'' programmable pacemakers using the MUGA study

    SciTech Connect

    Videen, J.S.; Huang, S.K.; Bazgan, I.D.; Mechling, E.; Patton, D.D.

    1985-05-01

    Programmable pacemakers (PPM) can be programmed to sense, stimulate, or inhibit atrial (A) and/or ventricular (V) electrical activity, and include variable A-V delays and other options. Selecting the optimum combination of settings for an individual patient can be a formidable task in the absence of noninvasive, objective, quantifiable measures of cardiac function. The authors attempt to determine whether the MUGA study could be adapted to such a task. MUGA studies were performed on 13 patients (pts) with PPM who had varying degrees of A-V block, during various settings of the PPM's. Studies were carried out 5-10 min. after pacing mode and A-V delay were changed, with the pt resting and supine. All 5 MUGA studies were carried out after a single injection of Tc-99m labeled autologous red blood cells. The results show that the VDD mode brings about a higher left ventricular ejection fraction (LVEF) and cardiac output (CO) than the DVI mode, and that either of these dual-chamber pacing modes produces a higher LVEF and CO than single-chamber pacing (VVI). Furthermore, a longer A-V delay was shown to improve LVEF and CO in patients with initially low LVEF. The MUGA study is simple, noninvasive, objective, and quantifiable, and can easily be repeated several times following a single injection. It can be used to ''fine tune'' programmable pacemakers for optimum hemodynamic performance.

  3. Fine tuning chloroplast movements through physical interactions between phototropins

    PubMed Central

    Sztatelman, Olga; Łabuz, Justyna; Hermanowicz, Paweł; Banaś, Agnieszka Katarzyna; Bażant, Aneta; Zgłobicki, Piotr; Aggarwal, Chhavi; Nadzieja, Marcin; Krzeszowiec, Weronika; Strzałka, Wojciech; Gabryś, Halina

    2016-01-01

    Phototropins are plant photoreceptors which regulate numerous responses to blue light, including chloroplast relocation. Weak blue light induces chloroplast accumulation, whereas strong light leads to an avoidance response. Two Arabidopsis phototropins are characterized by different light sensitivities. Under continuous light, both can elicit chloroplast accumulation, but the avoidance response is controlled solely by phot2. As well as continuous light, brief light pulses also induce chloroplast displacements. Pulses of 0.1s and 0.2s of fluence rate saturating the avoidance response lead to transient chloroplast accumulation. Longer pulses (up to 20s) trigger a biphasic response, namely transient avoidance followed by transient accumulation. This work presents a detailed study of transient chloroplast responses in Arabidopsis. Phototropin mutants display altered chloroplast movements as compared with the wild type: phot1 is characterized by weaker responses, while phot2 exhibits enhanced chloroplast accumulation, especially after 0.1s and 0.2s pulses. To determine the cause of these differences, the abundance and phosphorylation levels of both phototropins, as well as the interactions between phototropin molecules are examined. The formation of phototropin homo- and heterocomplexes is the most plausible explanation of the observed phenomena. The physiological consequences of this interplay are discussed, suggesting the universal character of this mechanism that fine-tunes plant reactions to blue light. Additionally, responses in mutants of different protein phosphatase 2A subunits are examined to assess the role of protein phosphorylation in signaling of chloroplast movements. PMID:27406783

  4. Fine-tuning of macrophage activation using synthetic rocaglate derivatives

    PubMed Central

    Bhattacharya, Bidisha; Chatterjee, Sujoy; Devine, William G.; Kobzik, Lester; Beeler, Aaron B.; Porco, John A.; Kramnik, Igor

    2016-01-01

    Drug-resistant bacteria represent a significant global threat. Given the dearth of new antibiotics, host-directed therapies (HDTs) are especially desirable. As IFN-gamma (IFNγ) plays a central role in host resistance to intracellular bacteria, including Mycobacterium tuberculosis, we searched for small molecules to augment the IFNγ response in macrophages. Using an interferon-inducible nuclear protein Ipr1 as a biomarker of macrophage activation, we performed a high-throughput screen and identified molecules that synergized with low concentration of IFNγ. Several active compounds belonged to the flavagline (rocaglate) family. In primary macrophages a subset of rocaglates 1) synergized with low concentrations of IFNγ in stimulating expression of a subset of IFN-inducible genes, including a key regulator of the IFNγ network, Irf1; 2) suppressed the expression of inducible nitric oxide synthase and type I IFN and 3) induced autophagy. These compounds may represent a basis for macrophage-directed therapies that fine-tune macrophage effector functions to combat intracellular pathogens and reduce inflammatory tissue damage. These therapies would be especially relevant to fighting drug-resistant pathogens, where improving host immunity may prove to be the ultimate resource. PMID:27086720

  5. Fine tuning chloroplast movements through physical interactions between phototropins.

    PubMed

    Sztatelman, Olga; Łabuz, Justyna; Hermanowicz, Paweł; Banaś, Agnieszka Katarzyna; Bażant, Aneta; Zgłobicki, Piotr; Aggarwal, Chhavi; Nadzieja, Marcin; Krzeszowiec, Weronika; Strzałka, Wojciech; Gabryś, Halina

    2016-09-01

    Phototropins are plant photoreceptors which regulate numerous responses to blue light, including chloroplast relocation. Weak blue light induces chloroplast accumulation, whereas strong light leads to an avoidance response. Two Arabidopsis phototropins are characterized by different light sensitivities. Under continuous light, both can elicit chloroplast accumulation, but the avoidance response is controlled solely by phot2. As well as continuous light, brief light pulses also induce chloroplast displacements. Pulses of 0.1s and 0.2s of fluence rate saturating the avoidance response lead to transient chloroplast accumulation. Longer pulses (up to 20s) trigger a biphasic response, namely transient avoidance followed by transient accumulation. This work presents a detailed study of transient chloroplast responses in Arabidopsis. Phototropin mutants display altered chloroplast movements as compared with the wild type: phot1 is characterized by weaker responses, while phot2 exhibits enhanced chloroplast accumulation, especially after 0.1s and 0.2s pulses. To determine the cause of these differences, the abundance and phosphorylation levels of both phototropins, as well as the interactions between phototropin molecules are examined. The formation of phototropin homo- and heterocomplexes is the most plausible explanation of the observed phenomena. The physiological consequences of this interplay are discussed, suggesting the universal character of this mechanism that fine-tunes plant reactions to blue light. Additionally, responses in mutants of different protein phosphatase 2A subunits are examined to assess the role of protein phosphorylation in signaling of chloroplast movements. © The Author 2016. Published by Oxford University Press on behalf of the Society for Experimental Biology.

  6. P2 receptor web: complexity and fine-tuning.

    PubMed

    Volonté, Cinzia; Amadio, Susanna; D'Ambrosi, Nadia; Colpi, Monica; Burnstock, Geoffrey

    2006-10-01

    The present review offers a new perspective on a family of receptors, termed P2 receptors, specific for nucleoside tri- and diphosphates of purines/pyrimidines. We emphasize here that while decoding the inputs of various related extracellular ligands, P2 receptors are a clear example of increasing biological complexity. They are represented by 7 ionotropic P2X and 8 metabotropic P2Y receptors; they have very heterogeneous ligands and binding characteristics, molecular properties, transduction mechanisms, cellular localization and protein-protein interactions. While the reason for this sophistication is unknown, a few compelling issues emerge while looking at such a rich variety. We ask, for instance, why so many different receptor subtypes are necessary for triggering biological properties and functions, and if these receptors are more than the sum of their single entities. A first possibility is that newly synthesized P2 proteins are casually located on the cell surface (stochastic hypothesis). Alternatively, distinct subunits are engaged on different cell phenotypes by genetic control (genetic determinism) and/or selective recruitment under physiopathological conditions and epigenetic stimuli (epigenetic determinism). Nevertheless, an appropriate way to both dissect the vast biological scenario and molecular complexity among P2 receptors and to integrate and upgrade their assortment is to regard them as a "combinatorial receptor web", that is, a dynamic architecture of P2 proteins demonstrating economic efficiency and involving a process of "fine-tuning", a mechanism which endorses the dynamic nature of all biological reactions. In the present analysis, we stimulate a scientific query about what contributes to such a vast P2 receptor sophistication.

  7. Tuning the Spring Constant of Cantilever-free Probe Arrays

    NASA Astrophysics Data System (ADS)

    Eichelsdoerfer, Daniel J.; Brown, Keith A.; Boya, Radha; Shim, Wooyoung; Mirkin, Chad A.

    2013-03-01

    The versatility of atomic force microscope (AFM) based techniques such as scanning probe lithography is due in part to the utilization of a cantilever that can be fabricated to match a desired application. In contrast, cantilever-free scanning probe lithography utilizes a low cost array of probes on a compliant backing layer that allows for high throughput nanofabrication but lacks the tailorability afforded by the cantilever in traditional AFM. Here, we present a method to measure and tune the spring constant of probes in a cantilever-free array by adjusting the mechanical properties of the underlying elastomeric layer. Using this technique, we are able to fabricate large-area silicon probe arrays with spring constants that can be tuned in the range from 7 to 150 N/m. This technique offers an advantage in that the spring constant depends linearly on the geometry of the probe, which is in contrast to traditional cantilever-based lithography where the spring constant varies as the cube of the beam width and thickness. To illustrate the benefit of utilizing a probe array with a lower spring constant, we pattern a block copolymer on a delicate 50 nm thick silicon nitride window.

  8. SUSY models under siege: LHC constraints and electroweak fine-tuning

    NASA Astrophysics Data System (ADS)

    Baer, Howard; Barger, Vernon; Mickelson, Dan; Padeffke-Kirkland, Maren

    2014-06-01

    Recent null results from LHC8 supersymmetry (SUSY) searches along with the discovery of a standard model (SM)-like Higgs boson with mass mh≃125.5 GeV indicates sparticle masses in the TeV range, causing tension with conventional measures of electroweak fine-tuning. We propose a simple fine-tuning rule which should be followed under any credible evaluation of fine-tuning. We believe that overestimates of electroweak fine-tuning by conventional measures all arise from violations of this rule. We show that to gain accord with the fine-tuning rule, then both the Higgs mass and the traditional ΔBG fine-tuning measures reduce to the model-independent electroweak fine-tuning measure ΔEW. This occurs by combining dependent contributions to mZ or mh into independent units. Then, using ΔEW, we evaluate EW fine-tuning for a variety of SUSY models including mSUGRA, NUHM1, NUHM2, mGMSB, mAMSB, hyper-charged AMSB, gaugino AMSB and nine cases of mixed moduli-anomaly (mirage) mediated SUSY breaking models while respecting LHC Higgs mass and B-decay constraints (we do not impose LHC8 sparticle mass constraints due to the possibility of compressed spectra within many of these models). We find mSUGRA, mGMSB and the AMSB models all to be highly fine-tuned. The NUHM1 model is moderately fine-tuned while NUHM2 which allows for radiatively driven naturalness (RNS) allows for fine-tuning at a meager 10% level in the case where m(Higgsinos)˜100-200 GeV and the TeV-scale top squarks are well mixed. Models with RNS may or may not be detectable at LHC14. A √s ˜500 GeV e+e- collider will be required to make a definitive search for the requisite light Higgsinos.

  9. Reducing the fine-tuning of gauge-mediated SUSY breaking

    NASA Astrophysics Data System (ADS)

    Casas, J. Alberto; Moreno, Jesús M.; Robles, Sandra; Rolbiecki, Krzysztof

    2016-08-01

    Despite their appealing features, models with gauge-mediated supersymmetry breaking (GMSB) typically present a high degree of fine-tuning, due to the initial absence of the top trilinear scalar couplings, A_t=0. In this paper, we carefully evaluate such a tuning, showing that is worse than per mil in the minimal model. Then, we examine some existing proposals to generate A_t≠ 0 term in this context. We find that, although the stops can be made lighter, usually the tuning does not improve (it may be even worse), with some exceptions, which involve the generation of A_t at one loop or tree level. We examine both possibilities and propose a conceptually simplified version of the latter; which is arguably the optimum GMSB setup (with minimal matter content), concerning the fine-tuning issue. The resulting fine-tuning is better than one per mil, still severe but similar to other minimal supersymmetric standard model constructions. We also explore the so-called "little A_t^2/m^2 problem", i.e. the fact that a large A_t-term is normally accompanied by a similar or larger sfermion mass, which typically implies an increase in the fine-tuning. Finally, we find the version of GMSB for which this ratio is optimized, which, nevertheless, does not minimize the fine-tuning.

  10. Fine-tuned Bee-Flower Coevolutionary State Hidden within Multiple Pollination Interactions

    PubMed Central

    Shimizu, Akira; Dohzono, Ikumi; Nakaji, Masayoshi; Roff, Derek A.; Miller III, Donald G.; Osato, Sara; Yajima, Takuya; Niitsu, Shûhei; Utsugi, Nozomu; Sugawara, Takashi; Yoshimura, Jin

    2014-01-01

    Relationships between flowers and pollinators are generally considered cases of mutualism since both agents gain benefits. Fine-tuned adaptations are usually found in the form of strict one-to-one coevolution between species. Many insect pollinators are, however, considered generalists, visiting numerous kinds of flowers, and many flower species (angiosperms) are also considered generalists, visited by many insect pollinators. We here describe a fine-tuned coevolutionary state of a flower-visiting bee that collects both nectar and pollen from an early spring flower visited by multiple pollinators. Detailed morphology of the bee proboscis is shown to be finely adjusted to the floral morphology and nectar production of the flower. Behavioral observations also confirm the precision of this mutualism. Our results suggest that a fine-tuned one-to-one coevolutionary state between a flower species and a pollinator species might be common, but frequently overlooked, in multiple flower-pollinator interactions. PMID:24496444

  11. Fine-tuning in GGM and the 126 GeV Higgs particle

    NASA Astrophysics Data System (ADS)

    Lalak, Zygmunt; Lewicki, Marek

    2013-05-01

    In this paper we reanalyze the issue of fine-tuning in supersymmetric models which feature Generalized Gauge Mediation (GGM) in the light of recent measurement of the mass of the light Higgs particle and taking into account available data on the value of the muon magnetic moment {g_{μ }}-2 . We consider GGM models with 3, 5 and 6 input parameters and reduce the fine-tuning by assuming simple relations between them at the high scale. We are able to find solutions which give the correct value of the light Higgs mass and are less fine-tuned than models with standard gauge mediation (and with gravity mediation), however one never finds fine-tung measure lower than about 102 if one neglects the data on {g_{μ }}-2 and and about four times more if one takes the constraint given by {g_{μ }}-2 into account. In general the current {g_{μ }}-2 data push the models towards the high fine-tuning region. It is interesting to note, that once one removes the contributions to the finetuning induced by μ and B μ , then in the case with neglected {g_{μ }}-2 constraint one can easily find realistic vacua with fine-tuning of order 1 or lower, while the fine-tung remains always large when the {g_{μ }}-2 constraint is enforced. One should note, that in the last case even a small shift of the light Higgs mass towards smaller values both reduces fine-tuning and helps to improve agreement of a model with {g_{μ }}-2 data.

  12. Optical properties of Ag nanoparticle arrays: Tuning the plasmon resonance

    NASA Astrophysics Data System (ADS)

    Simpson, J. R.; Drew, H. D.; Guo, S. H.; Phaneuf, R.

    2006-03-01

    Potential applications in the optical spectral range of meta-materials displaying negative permittivity and negative permeability has driven recent interest in nanostructured materials. Electromagnetic radiation incident on metallic nanoparticles induces a collective electronic excitation, or plasmon, which results in a detectable optical resonance. We report polarization-dependent transmission measurements of Ag nanoparticle arrays in the near-infrared to visible frequency range. E-beam lithography patterns arrays of nanoparticles from Ag deposited on transparent ITO-glass substrates. The array grid spacing is several hundred nanometers and the nanoparticle thickness and width are approximately 75,m. We vary the length to provide an in-plane aspect ratio (length to width) from 1,,to 4,,. The resonance shifts to lower (higher) energy with increasing aspect ratio for polarizations parallel to the long (short) axis. This work demonstrates the ability to tune optical resonance energies and widths in nanostructured materials with quality factors Q exceeding 10. Additionally, we discuss the effects of radiation damping, carrier scattering, and inhomogeneous broadening on the resonance widths.

  13. Localized electrical fine tuning of passive microwave and radio frequency devices

    DOEpatents

    Findikoglu, Alp T.

    2001-04-10

    A method and apparatus for the localized electrical fine tuning of passive multiple element microwave or RF devices in which a nonlinear dielectric material is deposited onto predetermined areas of a substrate containing the device. An appropriate electrically conductive material is deposited over predetermined areas of the nonlinear dielectric and the signal line of the device for providing electrical contact with the nonlinear dielectric. Individual, adjustable bias voltages are applied to the electrically conductive material allowing localized electrical fine tuning of the devices. The method of the present invention can be applied to manufactured devices, or can be incorporated into the design of the devices so that it is applied at the time the devices are manufactured. The invention can be configured to provide localized fine tuning for devices including but not limited to coplanar waveguides, slotline devices, stripline devices, and microstrip devices.

  14. A low-phase-noise ring oscillator with coarse and fine tuning in a standard CMOS process

    NASA Astrophysics Data System (ADS)

    Haijun, Gao; Lingling, Sun; Xiaofei, Kuang; Liheng, Lou

    2012-07-01

    A low-phase-noise wideband ring oscillator with coarse and fine tuning techniques implemented in a standard 65 nm CMOS process is presented. Direct frequency modulation in the ring oscillator is analyzed and a switched capacitor array is introduced to produce the lower VCO gain required to suppress this effect. A two-dimensional high-density stacked MOM-capacitor was adopted as the switched capacitor to make the proposed ring VCO compatible with standard CMOS processes. The designed ring VCO exhibits an output frequency from 480 to 1100 MHz, resulting in a tuning range of 78%, and the measured phase noise is -120 dBc/Hz @ 1 MHz at 495 MHz output. The VCO core consumes 3.84 mW under a 1.2 V supply voltage and the corresponding FOM is -169 dBc/Hz.

  15. Fine-Tuning Language Policy in Hong Kong Education: Stakeholders' Perceptions, Practices and Challenges

    ERIC Educational Resources Information Center

    Chan, Jim Y. H.

    2014-01-01

    The present study evaluates the impact of the fine-tuning medium of instruction (MOI) policy in Hong Kong in the early stages of its implementation. It explores the key stakeholders' perspectives on a school-based policy via a case study, which gathered multiple sources of qualitative data (i.e. focus groups/interviews, open-ended questionnaires,…

  16. Fine-tuning criteria for inflation and the search for primordial gravitational waves

    SciTech Connect

    Bird, Simeon; Peiris, Hiranya V.; Easther, Richard

    2008-10-15

    We revisit arguments that simple models of inflation with a small red tilt in the scalar power spectrum generically yield an observable tensor spectrum. We show that criteria for fine-tuning based upon the algebraic simplicity of the potential depend strongly upon the explicit assumptions they incorporate, particularly regarding the end of inflation. In addition, some models with algebraically simple potentials require carefully tuned initial field configurations, and not all types of fine-tuning are identifiable via the algebraic simplicity of the potential. Conversely, in the absence of a strong prior on the mechanism that ends inflation, we demonstrate the existence of potentials with vanishingly small tensor amplitudes which are natural in terms of both their algebraic form and initial conditions. We thus argue that proposed experiments (CMBPol or BBO) which make highly sensitive measurements of the tensor amplitude cannot definitively rule out the inflationary paradigm.

  17. Emission wavelength tuning of fluorescence by fine structural control of optical metamaterials with Fano resonance.

    PubMed

    Moritake, Y; Kanamori, Y; Hane, K

    2016-09-13

    We demonstrated fine emission wavelength tuning of quantum dot (QD) fluorescence by fine structural control of optical metamaterials with Fano resonance. An asymmetric-double-bar (ADB), which was composed of only two bars with slightly different bar lengths, was used to obtain Fano resonance in the optical region. By changing the short bar length of ADB structures with high dimensional accuracy in the order of 10 nm, resonant wavelengths of Fano resonance were controlled from 1296 to 1416 nm. Fluorescence of QDs embedded in a polymer layer on ADB metamaterials were modified due to coupling to Fano resonance and fine tuning from 1350 to 1376 nm was observed. Wavelength tuning of modified fluorescence was reproduced by analysis using absorption peaks of Fano resonance. Tuning range of modified fluorescence became narrow, which was interpreted by a simple Gaussian model and resulted from comparable FWHM in QD fluorescence and Fano resonant peaks. The results will help the design and fabrication of metamaterial devices with fluorophores such as light sources and biomarkers.

  18. Emission wavelength tuning of fluorescence by fine structural control of optical metamaterials with Fano resonance

    NASA Astrophysics Data System (ADS)

    Moritake, Y.; Kanamori, Y.; Hane, K.

    2016-09-01

    We demonstrated fine emission wavelength tuning of quantum dot (QD) fluorescence by fine structural control of optical metamaterials with Fano resonance. An asymmetric-double-bar (ADB), which was composed of only two bars with slightly different bar lengths, was used to obtain Fano resonance in the optical region. By changing the short bar length of ADB structures with high dimensional accuracy in the order of 10 nm, resonant wavelengths of Fano resonance were controlled from 1296 to 1416 nm. Fluorescence of QDs embedded in a polymer layer on ADB metamaterials were modified due to coupling to Fano resonance and fine tuning from 1350 to 1376 nm was observed. Wavelength tuning of modified fluorescence was reproduced by analysis using absorption peaks of Fano resonance. Tuning range of modified fluorescence became narrow, which was interpreted by a simple Gaussian model and resulted from comparable FWHM in QD fluorescence and Fano resonant peaks. The results will help the design and fabrication of metamaterial devices with fluorophores such as light sources and biomarkers.

  19. Emission wavelength tuning of fluorescence by fine structural control of optical metamaterials with Fano resonance

    PubMed Central

    Moritake, Y.; Kanamori, Y.; Hane, K.

    2016-01-01

    We demonstrated fine emission wavelength tuning of quantum dot (QD) fluorescence by fine structural control of optical metamaterials with Fano resonance. An asymmetric-double-bar (ADB), which was composed of only two bars with slightly different bar lengths, was used to obtain Fano resonance in the optical region. By changing the short bar length of ADB structures with high dimensional accuracy in the order of 10 nm, resonant wavelengths of Fano resonance were controlled from 1296 to 1416 nm. Fluorescence of QDs embedded in a polymer layer on ADB metamaterials were modified due to coupling to Fano resonance and fine tuning from 1350 to 1376 nm was observed. Wavelength tuning of modified fluorescence was reproduced by analysis using absorption peaks of Fano resonance. Tuning range of modified fluorescence became narrow, which was interpreted by a simple Gaussian model and resulted from comparable FWHM in QD fluorescence and Fano resonant peaks. The results will help the design and fabrication of metamaterial devices with fluorophores such as light sources and biomarkers. PMID:27622503

  20. Death receptors on reactive astrocytes: a key role in the fine tuning of brain inflammation?

    PubMed

    Dietrich, Pierre-Yves; Walker, Paul R; Saas, Philippe

    2003-02-25

    Immune responses protect the CNS against pathogens. However, the fact that there is little dispensable tissue in the brain makes regulation necessary to avoid disastrous immune-mediated damage. Astrocytes respond vigorously to any brain injury (e.g., tumor, stroke, AD, MS, HIV) and are postulated to play an important role in the fine tuning of brain inflammation. The authors propose that astrocytes use death receptors to modulate pro- and anti-inflammatory effects.

  1. An Undecanuclear Ferrimagnetic Cu9Dy2 Single Molecule Magnet Achieved through Ligand Fine-Tuning.

    PubMed

    Kühne, Irina A; Kostakis, George E; Anson, Christopher E; Powell, Annie K

    2016-05-02

    We describe the concept of increasing the nuclearity of a previously reported high-spin Cu5Gd2 core using a "fine-tuning" ligand approach. Thus, two Cu9Ln2 coordination clusters, with Ln = Dy (1) and Gd (2), were synthesized with the Gd compound having a ground spin state of (17)/2 and the Dy analogue showing single-molecule-magnet behavior in zero field.

  2. Post-fabrication fine-tuning of photonic crystal quantum well infrared photodetectors

    NASA Astrophysics Data System (ADS)

    Schartner, S.; Kalchmair, S.; Andrews, A. M.; Klang, P.; Schrenk, W.; Strasser, G.

    2009-06-01

    Photonic crystal (PC) devices require high fabrication accuracy for on demand positioning of resonances. We describe post-fabrication fine-tuning of a PC quantum well infrared photodetector (QWIP) by sidewall-deposition of silicon nitride. The PC resonance was shifted over a bandwidth of 43 cm-1. From photoresponse measurements we calculated a tuning coefficient of ∂ν/∂dSiN=-0.06 cm-1/nm. The QWIP responsivity did not suffer from nitride absorption while the PC resonance increased by a factor of 1.6. This shows that post-fabrication tuning by dielectric deposition with, e.g., silicon nitride is a feasible method to achieve precise implementations of PC devices.

  3. Fine-tuning of magnetic and microfluidic viscous forces for specific magnetic bead-based immunocomplex formation

    NASA Astrophysics Data System (ADS)

    Cornaglia, M.; Tekin, H. C.; Lehnert, T.; Gijs, M. A. M.

    2013-08-01

    We investigate the working principle of a novel type of microfluidic sandwich immunoassay, as used for the detection of biomarkers. The heterogeneous assay is based on the specific interactions between an array of functionalized superparamagnetic beads and a flow of secondary superparamagnetic beads that carry the antigens and are simultaneously used as detection labels. We identify the main forces governing the immunoassay performance and develop a combined finite element method/analytical model to predict and control these forces. The clue for the improved assay specificity is in the fine-tuning of inter-bead magnetic dipolar and microfluidic viscous forces, which allows strongly reducing non-specific interactions, while enhancing the specific formation of immunocomplexes. We exploit our theoretical model to explain the enhanced sensitivity of magnetic bead-based immunoassay experiments performed in microfluidic chips.

  4. Controlling the fine-tuning problem with singlet scalar dark matter

    NASA Astrophysics Data System (ADS)

    Chakraborty, Indrani; Kundu, Anirban

    2013-03-01

    Assuming that no other conventional new physics is found immediately at the LHC, we investigate how just the consistent solution of the scalar mass hierarchy problem points towards the minimal necessary field content. We show that to ameliorate the fine-tuning problem, one needs to introduce more scalar degrees of freedom. The simplest solution is one or more real singlets (with the possibility of combining two of them in a complex singlet), which may act as viable cold dark matter candidates, because the constraints on the scalar potential disfavor any mixing between the new scalar(s) with the SM doublet. Furthermore, the fine-tuning problem of the new scalars necessitates the introduction of vectorlike fermions. Thus, singlet scalar(s) and vector fermions are minimal enhancements over the Standard Model to alleviate the fine-tuning problem. We also show that the model predicts Landau poles for all the scalar couplings, whose positions depend only on the number of such singlets. Thus, introduction of some new physics at that scale becomes inevitable. We also discuss how the model confronts the LHC constraints and the latest XENON100 data.

  5. Fine-tuned grayscale optofluidic maskless lithography for three-dimensional freeform shape microstructure fabrication.

    PubMed

    Song, Suk-Heung; Kim, Kibeom; Choi, Sung-Eun; Han, Sangkwon; Lee, Ho-Suk; Kwon, Sunghoon; Park, Wook

    2014-09-01

    This article presents free-floating three-dimensional (3D) microstructure fabrication in a microfluidic channel using direct fine-tuned grayscale image lithography. The image is designed as a freeform shape and is composed of gray shades as light-absorbing features. Gray shade levels are modulated through multiple reflections of light in a digital micromirror device (DMD) to produce different height formations. Whereas conventional photolithography has several limitations in producing grayscale colors on photomask features, our method focuses on a maskless, single-shot process for fabrication of freeform 3D micro-scale shapes. The fine-tuned gray image is designed using an 8-bit grayscale color; thus, each pixel is capable of displaying 256 gray shades. The pattern of the UV light reflecting on the DMD is transferred to a photocurable resin flowing through a microfluidic channel. Here, we demonstrate diverse free-floating 3D microstructure fabrication using fine-tuned grayscale image lithography. Additionally, we produce polymeric microstructures with locally embedded gray encoding patterns, such as grayscale-encoded microtags. This functional microstructure can be applied to a biophysical detection system combined with 3D microstructures. This method would be suitable for fabricating 3D microstructures that have a specific morphology to be used for particular biological or medical applications.

  6. How conventional measures overestimate electroweak fine-tuning in supersymmetric theory

    NASA Astrophysics Data System (ADS)

    Baer, Howard; Barger, Vernon; Mickelson, Dan

    2013-11-01

    The lack of evidence for superparticles at the CERN LHC, along with the rather high value of the Higgs boson mass, has sharpened the perception that what remains of supersymmetric model parameter space suffers a high degree of electroweak fine-tuning (EWFT). We compare three different measures of fine-tuning in supersymmetric models. First, ΔHS measures a subset of terms containing large log contributions to mZ (and mh) that are inevitable in models defined at scales much higher than the electroweak scale. Second, the traditional ΔBG measures fractional variation in mZ against fractional variation of model parameters and allows for correlations among high scale parameters which are not included in ΔHS. Third, the model-independent ΔEW measures how naturally a model can generate the measured value of mZ=91.2GeV (or mh) in terms of weak scale parameters alone. We hypothesize an overarching ultimate theory (UTH) wherein the high scale soft terms are all correlated. The UTH might be contained within the more general effective supersymmetry theories which are popular in the literature. In the case of ΔHS, EWFT can be grossly overestimated by neglecting additional nonindependent terms which lead to large cancellations. In the case of ΔBG, EWFT can be overestimated by applying the measure to the effective theories instead of to the UTH. The measure ΔEW allows for the possibility of parameter correlations which should be present in the UTH and, since it is model independent, provides the same value of EWFT for the effective theories as should occur for the UTH. We find that the well-known minimal supergravity model/constrained minimal supersymmetric model is fine-tuned under all three measures so that it is unlikely to contain the UTH. The nonuniversal Higgs model NUHM2 appears fine-tuned with ΔHS,BG≳103. But since ΔEW can be as small as 7 (corresponding to 14% fine-tuning), it may contain the UTH for parameter ranges which allow for low true EWFT.

  7. Maskless lithography using point array technique for fine patterns

    NASA Astrophysics Data System (ADS)

    Nakajima, Fumitaka; Ohta, Eiji; Nakagawa, Takashi; Tachikawa, Masahiro; Takeda, Nobuo; Nishimoto, Nirou

    2015-07-01

    We made a steady progress in designing a maskless exposure system using the point array technique. An epoch-making high-resolution maskless lithography system with resolution of less than 1 micron half-pitch has been developed. Exposure results indicated that patterns were resolved up to 0.8 microns half-pitch. Smooth edges of the photoresist for various directions were also confirmed. It is distinctive characteristics of the point array technique. Another merit is coexistence of high resolution and high throughput. 4 inches wafers used in this evaluation were exposed within 30 minutes. Therefore, we consider that tact time of manufacturing a photomask can be shortened drastically. Finally we have challenged to apply an annular stop to our new projection optics system in order to achieve further improvement of optical performance. However, we confirmed that a sidelobe of optical spots, which became stronger by using the annular stop, exerted an undesirable influence upon imaging for fine patterns. Consequently, it became clear that suppressing the sidelobe as well as narrowing the mainlobe of optical spots is important for microlithography using the point array technique.

  8. Fine-tuning with brane-localized flux in 6D supergravity

    NASA Astrophysics Data System (ADS)

    Niedermann, Florian; Schneider, Robert

    2016-02-01

    There are claims in the literature that the cosmological constant problem could be solved in a braneworld model with two large (micron-sized) supersymmetric extra dimensions. The mechanism relies on two basic ingredients: first, the cosmological constant only curves the compact bulk geometry into a rugby shape while the 4D curvature stays flat. Second, a brane-localized flux term is introduced in order to circumvent Weinberg's fine-tuning argument, which otherwise enters here through a backdoor via the flux quantization condition. In this paper, we show that the latter mechanism does not work in the way it was designed: the only localized flux coupling that guarantees a flat on-brane geometry is one which preserves the scale invariance of the bulk theory. Consequently, Weinberg's argument applies, making a fine-tuning necessary again. The only remaining window of opportunity lies within scale invariance breaking brane couplings, for which the tuning could be avoided. Whether the corresponding 4D curvature could be kept under control and in agreement with the observed value will be answered in our companion paper [1].

  9. Fine-Tuning the Properties of Doped Multifunctional Materials by Controlled Reduction of Dopants.

    PubMed

    Barroux, Hugo; Jiang, Tengfei; Paul, Camille; Massuyeau, Florian; Génois, Romain; Gordon, Elijah E; Whangbo, Myung-Hwan; Jobic, Stéphane; Gautier, Romain

    2017-03-02

    The physical properties of doped multifunctional compounds are commonly tuned by controlling the amount of dopants, but this control is limited because all the properties are influenced simultaneously by this single parameter. Here, we present a strategy that enables the fine-tuning of a specific combination of properties by controlling the reduction of dopants. The feasibility of this approach was demonstrated by optimizing the near-IR photoluminescence of strontium titanate SrTiO3 :Ni for potential applications in biomedicine for a range of absorbance in the visible/near-IR region. We discussed how material properties, such as luminescence, conductivity, or photocatalytic properties can be designed by carefully controlling the ratio of dopants in different oxidation states.

  10. An Ensemble of Fine-Tuned Convolutional Neural Networks for Medical Image Classification.

    PubMed

    Kumar, Ashnil; Kim, Jinman; Lyndon, David; Fulham, Michael; Feng, Dagan

    2017-01-01

    The availability of medical imaging data from clinical archives, research literature, and clinical manuals, coupled with recent advances in computer vision offer the opportunity for image-based diagnosis, teaching, and biomedical research. However, the content and semantics of an image can vary depending on its modality and as such the identification of image modality is an important preliminary step. The key challenge for automatically classifying the modality of a medical image is due to the visual characteristics of different modalities: some are visually distinct while others may have only subtle differences. This challenge is compounded by variations in the appearance of images based on the diseases depicted and a lack of sufficient training data for some modalities. In this paper, we introduce a new method for classifying medical images that uses an ensemble of different convolutional neural network (CNN) architectures. CNNs are a state-of-the-art image classification technique that learns the optimal image features for a given classification task. We hypothesise that different CNN architectures learn different levels of semantic image representation and thus an ensemble of CNNs will enable higher quality features to be extracted. Our method develops a new feature extractor by fine-tuning CNNs that have been initialized on a large dataset of natural images. The fine-tuning process leverages the generic image features from natural images that are fundamental for all images and optimizes them for the variety of medical imaging modalities. These features are used to train numerous multiclass classifiers whose posterior probabilities are fused to predict the modalities of unseen images. Our experiments on the ImageCLEF 2016 medical image public dataset (30 modalities; 6776 training images, and 4166 test images) show that our ensemble of fine-tuned CNNs achieves a higher accuracy than established CNNs. Our ensemble also achieves a higher accuracy than methods in

  11. Fine-tuning and vacuum stability in the Wilsonian effective action

    NASA Astrophysics Data System (ADS)

    Krajewski, Tomasz; Lalak, Zygmunt

    2015-10-01

    We have computed the Wilsonian effective action in a simple model with a spontaneously broken chiral parity. The Wilsonian running of relevant parameters makes it possible to discuss in a consistent manner the issues of fine-tuning and the stability of the scalar potential. This has been compared with the standard picture based on a Gell-Mann-Low running. Since the Wilsonian running automatically includes integration of heavy degrees of freedom, the running differs markedly from the Gell-Mann-Low version. Similar behavior can be observed: the scalar mass-squared parameter and the quartic coupling can change sign from a positive to a negative one, due to the running which causes a spontaneous symmetry breaking or an instability in the renormalizable part of the potential for a given range of scales. However, care must be taken when drawing conclusions, because of the truncation of higher-dimension operators. Taking the scalar field's amplitude near the cutoff Λ may cancel the suppression due to the scale, and only the suppression due to small couplings partially justifies the truncation in this region. Also, when taking the cutoff higher, to include larger amplitudes of the fields, the higher-order irrelevant operators, whose coefficients grow with the scale, may affect the conclusion about the stability. The Gell-Mann-Low running allows one to resume relatively easily a class of operators corresponding to large logarithms to the form of the renormalization group equation improved effective potential which is valid over a huge range of scales. In the Wilsonian approach this would correspond to following the running of a large number of irrelevant operators, which is technically problematic. As for the issue of the fine-tuning, since in the Wilsonian approach power-law terms are not subtracted, one can clearly observe the quadratic sensitivity of a fine-tuning measure to the change of the cutoff scale. The Wilsonian version of the radiative symmetry

  12. Group I Metabotropic Glutamate Receptor Interacting Proteins: Fine-Tuning Receptor Functions in Health and Disease

    PubMed Central

    Kalinowska, Magdalena; Francesconi, Anna

    2016-01-01

    Group I metabotropic glutamate receptors mediate slow excitatory neurotransmission in the central nervous system and are critical to activity-dependent synaptic plasticity, a cellular substrate of learning and memory. Dysregulated receptor signaling is implicated in neuropsychiatric conditions ranging from neurodevelopmental to neurodegenerative disorders. Importantly, group I metabotropic glutamate receptor signaling functions can be modulated by interacting proteins that mediate receptor trafficking, expression and coupling efficiency to signaling effectors. These interactions afford cell- or pathway-specific modulation to fine-tune receptor function, thus representing a potential target for pharmacological interventions in pathological conditions. PMID:27296642

  13. Fine-tune lens-heating-induced focus drift with different process and illumination settings

    NASA Astrophysics Data System (ADS)

    Cui, Yuanting

    2001-09-01

    This study is to establish the relationship of lens heating (LH) performance with related process variables and develop the methodology for reducing LH induced focus drift for different products based on ASML LH algorithms and experiment data. Focus drift data is collected at certain LH machine constants for different process settings, such as different clear window images (CLW) in stepper jobs, different exposure doses, reticle transmission rates, and substrates. The further study is done at different illumination settings to establish the correlation between NA/sigma settings, focus drift and LH scaling factors ((mu) 1 (mu) 2). The characteristic (mu) 1, (mu) 2 -- NA/Ill relationship for this i-line stepper is generated using production batches. LH machine constants are fine-tuned based on the Poly layer for 0.30 micrometer Logic Mix-mode, 0.30 micrometer SRAM and 0.35 micrometer Embedded SRAM products. This work provides an accurate and practical way to fine-tune LH for all the i-line/DUV steppers based on the critical layer of representative products in a foundry fab.

  14. Fine-tuning convolutional deep features for MRI based brain tumor classification

    NASA Astrophysics Data System (ADS)

    Ahmed, Kaoutar B.; Hall, Lawrence O.; Goldgof, Dmitry B.; Liu, Renhao; Gatenby, Robert A.

    2017-03-01

    Prediction of survival time from brain tumor magnetic resonance images (MRI) is not commonly performed and would ordinarily be a time consuming process. However, current cross-sectional imaging techniques, particularly MRI, can be used to generate many features that may provide information on the patient's prognosis, including survival. This information can potentially be used to identify individuals who would benefit from more aggressive therapy. Rather than using pre-defined and hand-engineered features as with current radiomics methods, we investigated the use of deep features extracted from pre-trained convolutional neural networks (CNNs) in predicting survival time. We also provide evidence for the power of domain specific fine-tuning in improving the performance of a pre-trained CNN's, even though our data set is small. We fine-tuned a CNN initially trained on a large natural image recognition dataset (Imagenet ILSVRC) and transferred the learned feature representations to the survival time prediction task, obtaining over 81% accuracy in a leave one out cross validation.

  15. Adiponectin fine-tuning of liver regeneration dynamics revealed through cellular network modeling.

    PubMed

    Correnti, Jason M; Cook, Daniel; Aksamitiene, Edita; Swarup, Aditi; Ogunnaike, Babatunde; Vadigepalli, Rajanikanth; Hoek, Jan B

    2014-11-10

    Following partial hepatectomy, the liver initiates a regenerative program involving hepatocyte priming and replication driven by coordinated cytokine and growth factor actions. We investigated the mechanisms underlying Adiponectin's (Adn) regulation of liver regeneration through modulation of these mediators. Adn-/- mice showed delayed onset of hepatocyte replication, but accelerated cell cycle progression relative to wild-type mice, suggesting Adn has multiple effects fine-tuning the kinetics of liver regeneration. We developed a computational model describing the molecular and physiological kinetics of liver regeneration in Adn-/- mice. We employed this computational model to evaluate the underlying regulatory mechanisms. Our analysis predicted that Adn is required for an efficient early cytokine response to partial hepatectomy, but is inhibitory to later growth factor actions. Consistent with this prediction, Adn knockout reduced hepatocyte responses to IL-6 during the priming phase, but enhanced growth factor levels through peak hepatocyte replication. By contrast, supraphysiological concentrations of Adn resulting from rosiglitazone treatment suppressed regeneration by reducing growth factor levels during S phase, consistent with computational predictions. Together, these results revealed that Adn fine-tunes the progression of liver regeneration through dynamically modulating molecular mediator networks and cellular interactions within the liver. This article is protected by copyright. All rights reserved.

  16. Adiponectin fine-tuning of liver regeneration dynamics revealed through cellular network modelling.

    PubMed

    Correnti, Jason M; Cook, Daniel; Aksamitiene, Edita; Swarup, Aditi; Ogunnaike, Babatunde; Vadigepalli, Rajanikanth; Hoek, Jan B

    2015-01-15

    Following partial hepatectomy, the liver initiates a regenerative programme involving hepatocyte priming and replication driven by the coordinated actions of cytokine and growth factors. We investigated the mechanisms underlying adiponectin's (Adn) regulation of liver regeneration through modulation of these mediators. Adn(-/-) mice showed delayed onset of hepatocyte replication, but accelerated cell cycle progression relative to wild-type mice, suggesting Adn has multiple effects fine-tuning the kinetics of liver regeneration. We developed a computational model describing the molecular and physiological kinetics of liver regeneration in Adn(-/-) mice. We employed this computational model to evaluate the underlying regulatory mechanisms. Our analysis predicted that Adn is required for an efficient early cytokine response to partial hepatectomy, but is inhibitory to later growth factor actions. Consistent with this prediction, Adn knockout reduced hepatocyte responses to interleukin-6 during the priming phase, but enhanced growth factor levels through peak hepatocyte replication. By contrast, supraphysiological concentrations of Adn resulting from rosiglitazone treatment suppressed regeneration by reducing growth factor levels during S phase, consistent with computational predictions. Together, these results revealed that Adn fine-tunes the progression of liver regeneration through dynamically modulating molecular mediator networks and cellular interactions within the liver.

  17. Nonparametric Fine Tuning of Mixtures: Application to Non-Life Insurance Claims Distribution Estimation

    NASA Astrophysics Data System (ADS)

    Sardet, Laure; Patilea, Valentin

    When pricing a specific insurance premium, actuary needs to evaluate the claims cost distribution for the warranty. Traditional actuarial methods use parametric specifications to model claims distribution, like lognormal, Weibull and Pareto laws. Mixtures of such distributions allow to improve the flexibility of the parametric approach and seem to be quite well-adapted to capture the skewness, the long tails as well as the unobserved heterogeneity among the claims. In this paper, instead of looking for a finely tuned mixture with many components, we choose a parsimonious mixture modeling, typically a two or three-component mixture. Next, we use the mixture cumulative distribution function (CDF) to transform data into the unit interval where we apply a beta-kernel smoothing procedure. A bandwidth rule adapted to our methodology is proposed. Finally, the beta-kernel density estimate is back-transformed to recover an estimate of the original claims density. The beta-kernel smoothing provides an automatic fine-tuning of the parsimonious mixture and thus avoids inference in more complex mixture models with many parameters. We investigate the empirical performance of the new method in the estimation of the quantiles with simulated nonnegative data and the quantiles of the individual claims distribution in a non-life insurance application.

  18. Non-volatile resonance modes of a photonic cavity in diamond produced by fine-tuning

    NASA Astrophysics Data System (ADS)

    Lozovik, A.; Tordjman, M.; Meyler, B.; Bayn, I.; Salzman, J.; Kalish, R.

    2016-10-01

    Methods of fine-tuning the properties of 1D triangular nanobeam diamond based photonic devices, with the aim of enhancing the photon collection efficiency at predetermined wavelengths at ambient temperature, are described. Delicate control of the physical dimensions of the device, which is required to obtain these advantages, is achieved by the deposition of HfO2 monolayers (thickening) and by H2 plasma etching (thinning). These shift the optical properties of the thus-treated photonic crystal to the red and to the blue, respectively. The methods described here demonstrate a practical and straight-forward way to fine-tune the diamond photonic nanocavity into resonance with the zero-phonon line of the Nitrogen-Vacancy (NV-) centers at room temperature with the availability to be kept storable. This approach paves the way to obtain a non-volatile nanobeam structure available at a desired predetermined resonance mode for a subsequent usage of the NV- emission in ambient conditions. It may find valuable applications in diamond-based quantum computing and communications.

  19. An intramolecular disulfide bond designed in myoglobin fine-tunes both protein structure and peroxidase activity.

    PubMed

    Wu, Lei-Bin; Yuan, Hong; Zhou, Hu; Gao, Shu-Qin; Nie, Chang-Ming; Tan, Xiangshi; Wen, Ge-Bo; Lin, Ying-Wu

    2016-06-15

    Disulfide bond plays crucial roles in stabilization of protein structure and in fine-tuning protein functions. To explore an approach for rational heme protein design, we herein rationally introduced a pair of cysteines (F46C/M55C) into the scaffold of myoglobin (Mb), mimicking those in native neuroglobin. Molecular modeling suggested that it is possible for Cys46 and Cys55 to form an intramolecular disulfide bond, which was confirmed experimentally by ESI-MS analysis, DTNB reaction and CD spectrum. Moreover, it was shown that the spontaneously formed disulfide bond of Cys46-Cys55 fine-tunes not only the heme active site structure, but also the protein functions. The substitution of Phe46 with Ser46 in F46S Mb destabilizes the protein while facilitates H2O2 activation. Remarkably, the formation of an intramolecular disulfide bond of Cys46-Cys55 in F46C/M55C Mb improves the protein stability and regulates the heme site to be more favorable for substrate binding, resulting in enhanced peroxidase activity. This study provides valuable information of structure-function relationship for heme proteins regulated by an intramolecular disulfide bond, and also suggests that construction of such a covalent bond is useful for design of functional heme proteins. Copyright © 2016 Elsevier Inc. All rights reserved.

  20. Anthropic Reasoning about Fine-Tuning, and Neoclassical Cosmology: Providence, Omnipresence, and Observation Selection Theory

    NASA Astrophysics Data System (ADS)

    Walker, Theodore, Jr.

    2011-10-01

    Anthropic reasoning about observation selection effects upon the appearance of cosmic providential fine-tuning (fine-tuning that provides for life) is often motivated by a desire to avoid theological implications (implications favoring the idea of a divine cosmic provider) without appealing to sheer lucky-for-us-cosmic-jackpot happenstance and coincidence. Cosmic coincidence can be rendered less incredible by appealing to a multiverse context. Cosmic providence can be rendered non-theological by appealing to an agent-less providential purpose, or by appealing to less-than-omnipresent/local providers, such as alien intelligences creating life- providing baby universes. Instead of choosing either cosmic coincidence or cosmic providence, as though they were mutually exclusive; it is better to accept both. Neoclassical thought accepts coincidence and providence, plus many local providers and one omnipresent provider. Moreover, fundamental observation selection theory should distinguish the many local observers of some events from the one omnipresent observer of all events. Accepting both coincidence and providence avoids classical theology (providence without coincidence) and classical atheism (coincidence without providence), but not neoclassical theology (providence with coincidence). Cosmology cannot avoid the idea of an all-inclusive omnipresent providential dice-throwing living-creative whole of reality, an idea essential to neoclassical theology, and to neoclassical cosmology.

  1. Design and Fine-tuning Redox Potentials of Metalloproteins Involved in Electron Transfer in Bioenergetics

    PubMed Central

    Hosseinzadeh, Parisa; Lu, Yi

    2015-01-01

    Redox potentials are the major contributors to controlling the ET rates and thus regulating ET processes in the bioenergetics. To maximize the efficiency of the ET process, one needs to master the art of tuning of the E°, especially metalloproteins, as they represent major classes of ET proteins. In this review, we first describe the importance of tuning E° of ET centers, including the metalloproteins described above, and its role in regulating the ET in bioenergetic processes including photosynthesis and respiration. The major focus of this review is to summarize recent work in designing the ET centers, namely cupredoxins, cytochromes, and iron-sulfur proteins, and examples in design of protein networks involved these ET centers. We then discuss the factors that affect redox potentials of these ET centers including metal ion, the ligands to metal center and interactions beyond the primary ligand, especially non-covalent secondary coordination sphere interactions. We gave examples of strategies to fine-tune the redox potential using both natural and unnatural amino acids and native and nonnative cofactors. Several case studies are used to illustrate recent successes in this area. Outlooks for future endeavors are also provided. PMID:26301482

  2. Fine-tuning optical and electronic properties of graphene oxide for highly efficient perovskite solar cells

    NASA Astrophysics Data System (ADS)

    Liu, Tongfa; Kim, Dongcheon; Han, Hongwei; Mohd Yusoff, Abd. Rashid Bin; Jang, Jin

    2015-06-01

    Simplifying the process of fine-tuning the electronic and optical properties of graphene oxide (GO) is of importance in order to fully utilize it as the hole interfacial layer (HIL). We introduced silver trifluoromethanesulfonate (AgOTf), an inorganic chemical dopant, that tunes and controls the properties of single-layered GO films synthesized by chemical vapor deposition. The morphology, work function, mobility, sheet resistance, and transmittance of the GO film were systematically tuned by various doping concentrations. We further developed a solution-processable low-temperature hole interfacial layer (HIL) poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS):AgOTf-doped GO HIL in highly efficient perovskite solar cells. The PEDOT:PSS:AgOTf-doped GO HIL grants the desirable charge-collection in the HIL allowing the entire device to be prepared at temperatures less than 120 °C. The fabricated perovskite solar cells utilize a rigid substrate and demonstrate compelling photovoltaic performance with a power conversion efficiency (PCE) of 11.90%. Moreover, flexible devices prepared using a polyethylene terephthalate (PET)/ITO demonstrate a PCE of 9.67%, while ITO-free flexible devices adopting PET/aluminum doped zinc oxide (AZO)/silver (Ag)/AZO demonstrate a PCE of 7.97%. This study shows that the PEDOT:PSS:AgOTf-doped GO HIL has significant potential to contribute to the development of low-cost solar cells.

  3. Fine-tuning optical and electronic properties of graphene oxide for highly efficient perovskite solar cells.

    PubMed

    Liu, Tongfa; Kim, Dongcheon; Han, Hongwei; Yusoff, Abd Rashid bin Mohd; Jang, Jin

    2015-06-28

    Simplifying the process of fine-tuning the electronic and optical properties of graphene oxide (GO) is of importance in order to fully utilize it as the hole interfacial layer (HIL). We introduced silver trifluoromethanesulfonate (AgOTf), an inorganic chemical dopant, that tunes and controls the properties of single-layered GO films synthesized by chemical vapor deposition. The morphology, work function, mobility, sheet resistance, and transmittance of the GO film were systematically tuned by various doping concentrations. We further developed a solution-processable low-temperature hole interfacial layer (HIL) poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) ( PSS):AgOTf-doped GO HIL in highly efficient perovskite solar cells. The PSS:AgOTf-doped GO HIL grants the desirable charge-collection in the HIL allowing the entire device to be prepared at temperatures less than 120 °C. The fabricated perovskite solar cells utilize a rigid substrate and demonstrate compelling photovoltaic performance with a power conversion efficiency (PCE) of 11.90%. Moreover, flexible devices prepared using a polyethylene terephthalate (PET)/ITO demonstrate a PCE of 9.67%, while ITO-free flexible devices adopting PET/aluminum doped zinc oxide (AZO)/silver (Ag)/AZO demonstrate a PCE of 7.97%. This study shows that the PSS:AgOTf-doped GO HIL has significant potential to contribute to the development of low-cost solar cells.

  4. Bandgap tuning of silicon nanowire arrays for application to all-silicon tandem solar cells

    NASA Astrophysics Data System (ADS)

    Kurokawa, Yasuyoshi; Yano, Mitsugu; Miyajima, Shinsuke; Yamada, Akira

    2017-04-01

    To reduce the diameter of silicon nanowire (SiNW) arrays for bandgap tuning, a diameter reduction (DR) process incorporating H3PO4 oxidation and HF etching was conducted for SiNW arrays with a diameter of 30 nm and a length of 15 µm. After the DR process, the diameter of SiNW arrays around the tip was successfully reduced to below 10 nm. From the cathode luminescence measurement, the bandgap around the tip of SiNW arrays was estimated to be 1.2 eV, suggesting that bandgap widening occurred owing to the quantum size effect.

  5. Radiative natural supersymmetry: Reconciling electroweak fine-tuning and the Higgs boson mass

    NASA Astrophysics Data System (ADS)

    Baer, Howard; Barger, Vernon; Huang, Peisi; Mickelson, Dan; Mustafayev, Azar; Tata, Xerxes

    2013-06-01

    Models of natural supersymmetry seek to solve the little hierarchy problem by positing a spectrum of light Higgsinos ≲200-300GeV and light top squarks ≲600GeV along with very heavy squarks and TeV-scale gluinos. Such models have low electroweak fine-tuning and satisfy the LHC constraints. However, in the context of the minimal supersymmetric standard model, they predict too low a value of mh, are frequently in conflict with the measured b→sγ branching fraction, and the relic density of thermally produced Higgsino-like weakly interacting massive particles (WIMPs) falls well below dark matter measurements. We propose a framework dubbed radiative natural supersymmetry (RNS), which can be realized within the minimal supersymmetric standard model (avoiding the addition of extra exotic matter) and which maintains features such as gauge coupling unification and radiative electroweak symmetry breaking. The RNS model can be generated from supersymmetry (SUSY) grand unified theory type models with nonuniversal Higgs masses. Allowing for high-scale soft SUSY breaking Higgs mass mHu>m0 leads to automatic cancellations during renormalization group running and to radiatively-induced low fine-tuning at the electroweak scale. Coupled with large mixing in the top-squark sector, RNS allows for fine-tuning at the 3%-10% level with TeV-scale top squarks and a 125 GeV light Higgs scalar h. The model allows for at least a partial solution to the SUSY flavor, CP, and gravitino problems since first-/second-generation scalars (and the gravitino) may exist in the 10-30 TeV regime. We outline some possible signatures for RNS at the LHC, such as the appearance of low invariant mass opposite-sign isolated dileptons from gluino cascade decays. The smoking gun signature for RNS is the appearance of light Higgsinos at a linear e+e- collider. If the strong CP problem is solved by the Peccei-Quinn mechanism, then RNS naturally accommodates mixed axion-Higgsino cold dark matter, where the

  6. Phenotypic flexibility of gape anatomy fine-tunes the aquatic prey-capture system of newts.

    PubMed

    Van Wassenbergh, Sam; Heiss, Egon

    2016-07-07

    A unique example of phenotypic flexibility of the oral apparatus is present in newts (Salamandridae) that seasonally change between an aquatic and a terrestrial habitat. Newts grow flaps of skin between their upper and lower jaws, the labial lobes, to partly close the corners of the mouth when they adopt an aquatic lifestyle during their breeding season. Using hydrodynamic simulations based on μCT-scans and cranial kinematics during prey-capture in the smooth newt (Lissotriton vulgaris), we showed that this phenotypic flexibility is an adaptive solution to improve aquatic feeding performance: both suction distance and suction force increase by approximately 15% due to the labial lobes. As the subsequent freeing of the corners of the mouth by resorption of the labial lobes is assumed beneficial for the terrestrial capture of prey by the tongue, this flexibility of the mouth fine-tunes the process of capturing prey throughout the seasonal switching between water and land.

  7. Phenotypic flexibility of gape anatomy fine-tunes the aquatic prey-capture system of newts

    PubMed Central

    Van Wassenbergh, Sam; Heiss, Egon

    2016-01-01

    A unique example of phenotypic flexibility of the oral apparatus is present in newts (Salamandridae) that seasonally change between an aquatic and a terrestrial habitat. Newts grow flaps of skin between their upper and lower jaws, the labial lobes, to partly close the corners of the mouth when they adopt an aquatic lifestyle during their breeding season. Using hydrodynamic simulations based on μCT-scans and cranial kinematics during prey-capture in the smooth newt (Lissotriton vulgaris), we showed that this phenotypic flexibility is an adaptive solution to improve aquatic feeding performance: both suction distance and suction force increase by approximately 15% due to the labial lobes. As the subsequent freeing of the corners of the mouth by resorption of the labial lobes is assumed beneficial for the terrestrial capture of prey by the tongue, this flexibility of the mouth fine-tunes the process of capturing prey throughout the seasonal switching between water and land. PMID:27383663

  8. Phenotypic flexibility of gape anatomy fine-tunes the aquatic prey-capture system of newts

    NASA Astrophysics Data System (ADS)

    van Wassenbergh, Sam; Heiss, Egon

    2016-07-01

    A unique example of phenotypic flexibility of the oral apparatus is present in newts (Salamandridae) that seasonally change between an aquatic and a terrestrial habitat. Newts grow flaps of skin between their upper and lower jaws, the labial lobes, to partly close the corners of the mouth when they adopt an aquatic lifestyle during their breeding season. Using hydrodynamic simulations based on μCT-scans and cranial kinematics during prey-capture in the smooth newt (Lissotriton vulgaris), we showed that this phenotypic flexibility is an adaptive solution to improve aquatic feeding performance: both suction distance and suction force increase by approximately 15% due to the labial lobes. As the subsequent freeing of the corners of the mouth by resorption of the labial lobes is assumed beneficial for the terrestrial capture of prey by the tongue, this flexibility of the mouth fine-tunes the process of capturing prey throughout the seasonal switching between water and land.

  9. Spectral Fine Tuning of Cyanine Dyes: Electron Donor-Acceptor Substituted Analogues of Thiazole Orange†

    PubMed Central

    Rastede, Elizabeth E.; Tanha, Matteus; Yaron, David; Watkins, Simon C.; Waggoner, Alan S.; Armitage, Bruce A.

    2015-01-01

    The introduction of electron donor and acceptor groups at strategic locations on a fluorogenic cyanine dye allows fine-tuning of the absorption and emission spectra while preserving the ability of the dye to bind to biomolecular hosts such as double-stranded DNA and a single-chain antibody fragment originally selected for binding to the parent unsubstituted dye, thiazole orange (TO). The observed spectral shifts are consistent with calculated HOMO-LUMO energy gaps and reflect electron density localization on the quinoline half of TO in the LUMO. A dye bearing donating methoxy and withdrawing trifluoromethyl groups on the benzothiazole and quinoline rings, respectively, shifts the absorption spectrum to sufficiently longer wavelengths to allow excitation at green wavelengths as opposed to the parent dye, which is optimally excited in the blue. PMID:26171668

  10. Lorentz invariance and quantum gravity: an additional fine-tuning problem?

    PubMed

    Collins, John; Perez, Alejandro; Sudarsky, Daniel; Urrutia, Luis; Vucetich, Héctor

    2004-11-05

    Trying to combine standard quantum field theories with gravity leads to a breakdown of the usual structure of space time at around the Planck length, 1.6x10(-35) m, with possible violations of Lorentz invariance. Calculations of preferred-frame effects in quantum gravity have further motivated high precision searches for Lorentz violation. Here, we explain that combining known elementary particle interactions with a Planck-scale preferred frame gives rise to Lorentz violation at the percent level, some 20 orders of magnitude higher than earlier estimates, unless the bare parameters of the theory are unnaturally strongly fine tuned. Therefore an important task is not just the improvement of the precision of searches for violations of Lorentz invariance, but also the search for theoretical mechanisms for automatically preserving Lorentz invariance.

  11. Spontaneous fine-tuning to environment in many-species chemical reaction networks

    NASA Astrophysics Data System (ADS)

    Horowitz, Jordan M.; England, Jeremy L.

    2017-07-01

    A chemical mixture that continually absorbs work from its environment may exhibit steady-state chemical concentrations that deviate from their equilibrium values. Such behavior is particularly interesting in a scenario where the environmental work sources are relatively difficult to access, so that only the proper orchestration of many distinct catalytic actors can power the dissipative flux required to maintain a stable, far-from-equilibrium steady state. In this article, we study the dynamics of an in silico chemical network with random connectivity in an environment that makes strong thermodynamic forcing available only to rare combinations of chemical concentrations. We find that the long-time dynamics of such systems are biased toward states that exhibit a fine-tuned extremization of environmental forcing.

  12. Zipf's Law and Criticality in Multivariate Data without Fine-Tuning

    NASA Astrophysics Data System (ADS)

    Schwab, David J.; Nemenman, Ilya; Mehta, Pankaj

    2014-08-01

    The joint probability distribution of states of many degrees of freedom in biological systems, such as firing patterns in neural networks or antibody sequence compositions, often follows Zipf's law, where a power law is observed on a rank-frequency plot. This behavior has been shown to imply that these systems reside near a unique critical point where the extensive parts of the entropy and energy are exactly equal. Here, we show analytically, and via numerical simulations, that Zipf-like probability distributions arise naturally if there is a fluctuating unobserved variable (or variables) that affects the system, such as a common input stimulus that causes individual neurons to fire at time-varying rates. In statistics and machine learning, these are called latent-variable or mixture models. We show that Zipf's law arises generically for large systems, without fine-tuning parameters to a point. Our work gives insight into the ubiquity of Zipf's law in a wide range of systems.

  13. Fine-tuning by strigolactones of root response to low phosphate.

    PubMed

    Kapulnik, Yoram; Koltai, Hinanit

    2016-03-01

    Strigolactones are plant hormones that regulate the development of different plant parts. In the shoot, they regulate axillary bud outgrowth and in the root, root architecture and root-hair length and density. Strigolactones are also involved with communication in the rhizosphere, including enhancement of hyphal branching of arbuscular mycorrhizal fungi. Here we present the role and activity of strigolactones under conditions of phosphate deprivation. Under these conditions, their levels of biosynthesis and exudation increase, leading to changes in shoot and root development. At least for the latter, these changes are likely to be associated with alterations in auxin transport and sensitivity. On the other hand, strigolactones may positively affect plant-mycorrhiza interactions and thereby promote phosphate acquisition by the plant. Strigolactones may be a way for plants to fine-tune their growth pattern under phosphate deprivation.

  14. How SUMOylation Fine-Tunes the Fanconi Anemia DNA Repair Pathway

    PubMed Central

    Coleman, Kate E.; Huang, Tony T.

    2016-01-01

    Fanconi anemia (FA) is a rare human genetic disorder characterized by developmental defects, bone marrow failure and cancer predisposition, primarily due to a deficiency in the repair of DNA interstrand crosslinks (ICLs). ICL repair through the FA DNA repair pathway is a complicated multi-step process, involving at least 19 FANC proteins and coordination of multiple DNA repair activities, including homologous recombination, nucleotide excision repair and translesion synthesis (TLS). SUMOylation is a critical regulator of several DNA repair pathways, however, the role of this modification in controlling the FA pathway is poorly understood. Here, we summarize recent advances in the fine-tuning of the FA pathway by small ubiquitin-like modifier (SUMO)-targeted ubiquitin ligases (STUbLs) and other SUMO-related interactions, and discuss the implications of these findings in the design of novel therapeutics for alleviating FA-associated condition, including cancer. PMID:27148358

  15. Origin of the fundamental plane of elliptical galaxies in the Coma cluster without fine-tuning

    NASA Astrophysics Data System (ADS)

    Chiu, Mu-Chen; Ko, Chung-Ming; Shu, Chenggang

    2017-03-01

    Thirty years after the discovery of the fundamental plane, explanations of the tilt of the fundamental plane with respect to the virial plane are still in need of fine-tuning. In this paper, we try to explore the origin of this tilt from the perspective of modified Newtonian dynamics (MOND) by applying the 16 Coma galaxies available in J. Thomas et al. [Mon. Not. R. Astron. Soc. 415, 545 (2011), 10.1111/j.1365-2966.2011.18725.x]. Based on the mass models that can reproduce de Vaucouleurs' law closely, we find that the tilt of the traditional fundamental plane is naturally explained by the simple form of the MONDian interpolating function, if we assume a well motivated choice of anisotropic velocity distribution, and adopt the Kroupa or Salpeter stellar mass-to-light ratio. Our analysis does not necessarily rule out a varying stellar mass-to-light ratio.

  16. Resazurin Live Cell Assay: Setup and Fine-Tuning for Reliable Cytotoxicity Results.

    PubMed

    Rodríguez-Corrales, José Á; Josan, Jatinder S

    2017-01-01

    In vitro cytotoxicity tests allow for fast and inexpensive screening of drug efficacy prior to in vivo studies. The resazurin assay (commercialized as Alamar Blue(®)) has been extensively utilized for this purpose in 2D and 3D cell cultures, and high-throughput screening. However, improper or lack of assay validation can generate unreliable results and limit reproducibility. Herein, we report a detailed protocol for the optimization of the resazurin assay to determine relevant analytical (limits of detection, quantification, and linear range) and biological (growth kinetics) parameters, and, thus, provide accurate cytotoxicity results. Fine-tuning of the resazurin assay will allow accurate and fast quantification of cytotoxicity for drug discovery. Unlike more complicated methods (e.g., mass spectrometry), this assay utilizes fluorescence spectroscopy and, thus, provides a less costly alternative to observe changes in the reductase proteome of the cells.

  17. A voltage-dependent chloride channel fine-tunes photosynthesis in plants

    PubMed Central

    Herdean, Andrei; Teardo, Enrico; Nilsson, Anders K.; Pfeil, Bernard E.; Johansson, Oskar N.; Ünnep, Renáta; Nagy, Gergely; Zsiros, Ottó; Dana, Somnath; Solymosi, Katalin; Garab, Győző; Szabó, Ildikó; Spetea, Cornelia; Lundin, Björn

    2016-01-01

    In natural habitats, plants frequently experience rapid changes in the intensity of sunlight. To cope with these changes and maximize growth, plants adjust photosynthetic light utilization in electron transport and photoprotective mechanisms. This involves a proton motive force (PMF) across the thylakoid membrane, postulated to be affected by unknown anion (Cl−) channels. Here we report that a bestrophin-like protein from Arabidopsis thaliana functions as a voltage-dependent Cl− channel in electrophysiological experiments. AtVCCN1 localizes to the thylakoid membrane, and fine-tunes PMF by anion influx into the lumen during illumination, adjusting electron transport and the photoprotective mechanisms. The activity of AtVCCN1 accelerates the activation of photoprotective mechanisms on sudden shifts to high light. Our results reveal that AtVCCN1, a member of a conserved anion channel family, acts as an early component in the rapid adjustment of photosynthesis in variable light environments. PMID:27216227

  18. viral silencing suppressors: Tools forged to fine-tune host-pathogen coexistence.

    PubMed

    Csorba, Tibor; Kontra, Levente; Burgyán, József

    2015-05-01

    RNA silencing is a homology-dependent gene inactivation mechanism that regulates a wide range of biological processes including antiviral defense. To deal with host antiviral responses viruses evolved mechanisms to avoid or counteract this, most notably through expression of viral suppressors of RNA silencing. Besides working as silencing suppressors, these proteins may also fulfill other functions during infection. In many cases the interplay between the suppressor function and other "unrelated" functions remains elusive. We will present host factors implicated in antiviral pathways and summarize the current status of knowledge about the diverse viral suppressors' strategies acting at various steps of antiviral silencing in plants. Besides, we will consider the multi-functionality of these versatile proteins and related biochemical processes in which they may be involved in fine-tuning the plant-virus interaction. Finally, we will present the current applications and discuss perspectives of the use of these proteins in molecular biology and biotechnology.

  19. Fine-tuning the size and minimizing the noise of solid-state nanopores.

    PubMed

    Beamish, Eric; Kwok, Harold; Tabard-Cossa, Vincent; Godin, Michel

    2013-10-31

    Solid-state nanopores have emerged as a versatile tool for the characterization of single biomolecules such as nucleic acids and proteins. However, the creation of a nanopore in a thin insulating membrane remains challenging. Fabrication methods involving specialized focused electron beam systems can produce well-defined nanopores, but yield of reliable and low-noise nanopores in commercially available membranes remains low and size control is nontrivial. Here, the application of high electric fields to fine-tune the size of the nanopore while ensuring optimal low-noise performance is demonstrated. These short pulses of high electric field are used to produce a pristine electrical signal and allow for enlarging of nanopores with subnanometer precision upon prolonged exposure. This method is performed in situ in an aqueous environment using standard laboratory equipment, improving the yield and reproducibility of solid-state nanopore fabrication.

  20. Fine-tuning the Size and Minimizing the Noise of Solid-state Nanopores

    PubMed Central

    Beamish, Eric; Kwok, Harold; Tabard-Cossa, Vincent; Godin, Michel

    2013-01-01

    Solid-state nanopores have emerged as a versatile tool for the characterization of single biomolecules such as nucleic acids and proteins1. However, the creation of a nanopore in a thin insulating membrane remains challenging. Fabrication methods involving specialized focused electron beam systems can produce well-defined nanopores, but yield of reliable and low-noise nanopores in commercially available membranes remains low2,3 and size control is nontrivial4,5. Here, the application of high electric fields to fine-tune the size of the nanopore while ensuring optimal low-noise performance is demonstrated. These short pulses of high electric field are used to produce a pristine electrical signal and allow for enlarging of nanopores with subnanometer precision upon prolonged exposure. This method is performed in situ in an aqueous environment using standard laboratory equipment, improving the yield and reproducibility of solid-state nanopore fabrication. PMID:24300128

  1. Dosage compensation in Drosophila melanogaster: epigenetic fine-tuning of chromosome-wide transcription.

    PubMed

    Conrad, Thomas; Akhtar, Asifa

    2012-01-18

    Dosage compensation is an epigenetic mechanism that normalizes gene expression from unequal copy numbers of sex chromosomes. Different organisms have evolved alternative molecular solutions to this task. In Drosophila melanogaster, transcription of the single male X chromosome is upregulated by twofold in a process orchestrated by the dosage compensation complex. Despite this conceptual simplicity, dosage compensation involves multiple coordinated steps to recognize and activate the entire X chromosome. We are only beginning to understand the intriguing interplay between multiple levels of local and long-range chromatin regulation required for the fine-tuned transcriptional activation of a heterogeneous gene population. This Review highlights the known facts and open questions of dosage compensation in D. melanogaster.

  2. Spontaneous fine-tuning to environment in many-species chemical reaction networks.

    PubMed

    Horowitz, Jordan M; England, Jeremy L

    2017-07-18

    A chemical mixture that continually absorbs work from its environment may exhibit steady-state chemical concentrations that deviate from their equilibrium values. Such behavior is particularly interesting in a scenario where the environmental work sources are relatively difficult to access, so that only the proper orchestration of many distinct catalytic actors can power the dissipative flux required to maintain a stable, far-from-equilibrium steady state. In this article, we study the dynamics of an in silico chemical network with random connectivity in an environment that makes strong thermodynamic forcing available only to rare combinations of chemical concentrations. We find that the long-time dynamics of such systems are biased toward states that exhibit a fine-tuned extremization of environmental forcing.

  3. Improved transgene expression fine-tuning in mammalian cells using a novel transcription-translation network.

    PubMed

    Malphettes, Laetitia; Fussenegger, Martin

    2006-08-05

    Following the discovery of RNA interference (RNAi) and related phenomena, novel regulatory processes, attributable to small non-protein-coding RNAs, continue to emerge. Capitalizing on the ability of artificial short interfering RNAs (siRNAs) to trigger degradation of specific target transcripts, and thereby silence desired gene expression, we designed and characterized a generic transcription-translation network in which it is possible to fine-tune heterologous protein production by coordinated transcription and translation interventions using macrolide and tetracycline antibiotics. Integration of siRNA-specific target sequences (TAGs) into the 5' or 3' untranslated regions (5'UTR, 3'UTR) of a desired constitutive transcription unit rendered transgene-encoded protein (erythropoietin, EPO; human placental alkaline phosphatase, SEAP; human vascular endothelial growth factor 121, VEGF(121)) production in mammalian cells responsive to siRNA levels that can be fine-tuned by macrolide-adjustable RNA polymerase II- or III-dependent promoters. Coupling of such macrolide-responsive siRNA-triggered translation control with tetracycline-responsive transcription of tagged transgene mRNAs created an antibiotic-adjustable two-input transcription-translation network characterized by elimination of detectable leaky expression with no reduction in maximum protein production levels. This transcription-translation network revealed transgene mRNA depletion to be dependent on siRNA and mRNA levels and that translation control was able to eliminate basal expression inherent to current transcription control modalities. Coupled transcription-translation circuitries have the potential to lead the way towards composite artificial regulatory networks, to enable complex therapeutic interventions in future biopharmaceutical manufacturing, gene therapy and tissue engineering initiatives.

  4. Synthetic Core Promoters as Universal Parts for Fine-Tuning Expression in Different Yeast Species.

    PubMed

    Portela, Rui M C; Vogl, Thomas; Kniely, Claudia; Fischer, Jasmin E; Oliveira, Rui; Glieder, Anton

    2017-03-17

    Synthetic biology and metabolic engineering experiments frequently require the fine-tuning of gene expression to balance and optimize protein levels of regulators or metabolic enzymes. A key concept of synthetic biology is the development of modular parts that can be used in different contexts. Here, we have applied a computational multifactor design approach to generate de novo synthetic core promoters and 5' untranslated regions (UTRs) for yeast cells. In contrast to upstream cis-regulatory modules (CRMs), core promoters are typically not subject to specific regulation, making them ideal engineering targets for gene expression fine-tuning. 112 synthetic core promoter sequences were designed on the basis of the sequence/function relationship of natural core promoters, nucleosome occupancy and the presence of short motifs. The synthetic core promoters were fused to the Pichia pastoris AOX1 CRM, and the resulting activity spanned more than a 200-fold range (0.3% to 70.6% of the wild type AOX1 level). The top-ten synthetic core promoters with highest activity were fused to six additional CRMs (three in P. pastoris and three in Saccharomyces cerevisiae). Inducible CRM constructs showed significantly higher activity than constitutive CRMs, reaching up to 176% of natural core promoters. Comparing the activity of the same synthetic core promoters fused to different CRMs revealed high correlations only for CRMs within the same organism. These data suggest that modularity is maintained to some extent but only within the same organism. Due to the conserved role of eukaryotic core promoters, this rational design concept may be transferred to other organisms as a generic engineering tool.

  5. Synthetic Core Promoters as Universal Parts for Fine-Tuning Expression in Different Yeast Species

    PubMed Central

    2016-01-01

    Synthetic biology and metabolic engineering experiments frequently require the fine-tuning of gene expression to balance and optimize protein levels of regulators or metabolic enzymes. A key concept of synthetic biology is the development of modular parts that can be used in different contexts. Here, we have applied a computational multifactor design approach to generate de novo synthetic core promoters and 5′ untranslated regions (UTRs) for yeast cells. In contrast to upstream cis-regulatory modules (CRMs), core promoters are typically not subject to specific regulation, making them ideal engineering targets for gene expression fine-tuning. 112 synthetic core promoter sequences were designed on the basis of the sequence/function relationship of natural core promoters, nucleosome occupancy and the presence of short motifs. The synthetic core promoters were fused to the Pichia pastoris AOX1 CRM, and the resulting activity spanned more than a 200-fold range (0.3% to 70.6% of the wild type AOX1 level). The top-ten synthetic core promoters with highest activity were fused to six additional CRMs (three in P. pastoris and three in Saccharomyces cerevisiae). Inducible CRM constructs showed significantly higher activity than constitutive CRMs, reaching up to 176% of natural core promoters. Comparing the activity of the same synthetic core promoters fused to different CRMs revealed high correlations only for CRMs within the same organism. These data suggest that modularity is maintained to some extent but only within the same organism. Due to the conserved role of eukaryotic core promoters, this rational design concept may be transferred to other organisms as a generic engineering tool. PMID:27973777

  6. The Parametric Study and Fine-Tuning of Bow-Tie Slot Antenna with Loaded Stub

    PubMed Central

    2017-01-01

    A printed Bow-Tie slot antenna with loaded stub is proposed and the effects of changing the dimensions of the slot area, the stub and load sizes are considered in this paper. These parameters have a considerable effect on the antenna characteristics as well as its performance. An in-depth parametric study of these dimensions is presented. This paper proposes the necessary conditions for initial approximation of dimensions needed to design this antenna. In order to achieve the desired performance of the antenna fine tuning of all sizes of these parameters is required. The parametric studies used in this paper provide proper trends for initiation and tuning the design. A prototype of the antenna for 1.7GHz to 2.6GHz band is fabricated. Measurements conducted verify that the designed antenna has wideband characteristics with 50% bandwidth around the center frequency of 2.1GHz. Conducted measurements for reflection coefficient (S11) and radiation pattern also validate our simulation results. PMID:28114354

  7. The Parametric Study and Fine-Tuning of Bow-Tie Slot Antenna with Loaded Stub.

    PubMed

    Shafiei, M M; Moghavvemi, Mahmoud; Wan Mahadi, Wan Nor Liza

    2017-01-01

    A printed Bow-Tie slot antenna with loaded stub is proposed and the effects of changing the dimensions of the slot area, the stub and load sizes are considered in this paper. These parameters have a considerable effect on the antenna characteristics as well as its performance. An in-depth parametric study of these dimensions is presented. This paper proposes the necessary conditions for initial approximation of dimensions needed to design this antenna. In order to achieve the desired performance of the antenna fine tuning of all sizes of these parameters is required. The parametric studies used in this paper provide proper trends for initiation and tuning the design. A prototype of the antenna for 1.7GHz to 2.6GHz band is fabricated. Measurements conducted verify that the designed antenna has wideband characteristics with 50% bandwidth around the center frequency of 2.1GHz. Conducted measurements for reflection coefficient (S11) and radiation pattern also validate our simulation results.

  8. Finely tuning MOFs towards high-performance post-combustion CO2 capture materials.

    PubMed

    Wang, Qian; Bai, Junfeng; Lu, Zhiyong; Pan, Yi; You, Xiaozeng

    2016-01-11

    CO2 capture science and technology, particularly for the post-combustion CO2 capture, has become one of very important research fields, due to great concern of global warming. Metal-organic frameworks (MOFs) with a unique feature of structural fine-tunability, unlike the traditional porous solid materials, can provide many and powerful platforms to explore high-performance adsorbents for post-combustion CO2 capture. Until now, several strategies for finely tuning MOF structures have been developed, in which either the larger quadrupole moment and polarizability of CO2 are considered: metal ion change (I), functional groups attachment (II) and functional group insertion (III), vary the electronic nature of the pore surface; or targeting the smaller kinetic diameter of CO2 over N2 is focused on: framework interpenetration (IV), ligand shortening (V) and coordination site shifting (VI) contract the pore size of frameworks to improve their CO2 capture properties. In this review, from the viewpoint of synthetic materials scientists/chemists, we would like to introduce and summarize these strategies based upon recent work published by other groups and ourselves.

  9. Microglia and synapse interactions: fine tuning neural circuits and candidate molecules

    PubMed Central

    Miyamoto, Akiko; Wake, Hiroaki; Moorhouse, Andrew J.; Nabekura, Junichi

    2013-01-01

    Brain function depends critically on the interactions among the underlying components that comprise neural circuits. This includes coordinated activity in pre-synaptic and postsynaptic neuronal elements, but also in the non-neuronal elements such as glial cells. Microglia are glial cells in the central nervous system (CNS) that have well-known roles in neuronal immune function, responding to infections and brain injury and influencing the progress of neurodegenerative disorders. However, microglia are also surveyors of the healthy brain, continuously extending and retracting their processes and making contacts with pre- and postsynaptic elements of neural circuits, a process that clearly consumes considerable energy. Pruning of synapses during development and in response to injury has also been documented, and we propose that this extensive surveillance of the brain parenchyma in adult healthy brain results in similar “fine-tuning” of neural circuits. A reasonable extension is that a dysfunction of such a homeostatic role of microglia could be a primary cause of neuronal disease. Indeed, neuronal functions including cognition, personality, and information processing are affected by immune status. In this review we focus on the interactions between microglia and synapses, the possible cellular and molecular mechanisms that mediate such contacts, and the possible implications these interactions may have in the fine tuning of neural circuits that is so important for physiological brain function. PMID:23720611

  10. Fine tuning of optical signals in nanoporous anodic alumina photonic crystals by apodized sinusoidal pulse anodisation.

    PubMed

    Santos, Abel; Law, Cheryl Suwen; Chin Lei, Dominique Wong; Pereira, Taj; Losic, Dusan

    2016-11-03

    In this study, we present an advanced nanofabrication approach to produce gradient-index photonic crystal structures based on nanoporous anodic alumina. An apodization strategy is for the first time applied to a sinusoidal pulse anodisation process in order to engineer the photonic stop band of nanoporous anodic alumina (NAA) in depth. Four apodization functions are explored, including linear positive, linear negative, logarithmic positive and logarithmic negative, with the aim of finely tuning the characteristic photonic stop band of these photonic crystal structures. We systematically analyse the effect of the amplitude difference (from 0.105 to 0.840 mA cm(-2)), the pore widening time (from 0 to 6 min), the anodisation period (from 650 to 950 s) and the anodisation time (from 15 to 30 h) on the quality and the position of the characteristic photonic stop band and the interferometric colour of these photonic crystal structures using the aforementioned apodization functions. Our results reveal that a logarithmic negative apodisation function is the most optimal approach to obtain unprecedented well-resolved and narrow photonic stop bands across the UV-visible-NIR spectrum of NAA-based gradient-index photonic crystals. Our study establishes a fully comprehensive rationale towards the development of unique NAA-based photonic crystal structures with finely engineered optical properties for advanced photonic devices such as ultra-sensitive optical sensors, selective optical filters and all-optical platforms for quantum computing.

  11. Firsthand in situ observation of active fine laser tuning by combining a temperature gradient and a CLC wedge cell structure.

    PubMed

    Jeong, Mi-Yun; Cha, Jihun

    2015-08-10

    In situ direct observation of the lasing process in a cholesteric liquid crystal (CLC) laser array using a CMOS camera was used to investigate discontinuous laser tuning in a parallel CLC cell. In accordance with the discontinuous pitch change by thermal energy transfer, at the same time the laser wavelength undergoes an immediate and discontinuous shift. And we found out the reason why the CLC phase has domain textures. And this work develops a simple active tunable laser array by forming a spatial temperature gradient along a wedge CLC cell. With this new strategy, only just about 7 nm laser tuning range at room temperature is extremely widened over the 105 nm wavelength range with about 0.2 nm tuning resolution. Furthermore, there is no aging effect because the employed CLC array has only one chiral molecular concentration. This strategy could be used in a practical CLC laser device application.

  12. Automated tuning of an eight-channel cardiac transceive array at 7 tesla using piezoelectric actuators

    PubMed Central

    Keith, Graeme A; Rodgers, Christopher T; Hess, Aaron T; Snyder, Carl J; Vaughan, J Thomas; Robson, Matthew D

    2015-01-01

    Purpose Ultra-high field (UHF) MR scanning in the body requires novel coil designs due to B1 field inhomogeneities. In the transverse electromagnetic field (TEM) design, maximum B1 transmit power can only be achieved if each individual transmit element is tuned and matched for different coil loads, which requires a considerable amount of valuable scanner time. Methods An integrated system for autotuning a multichannel parallel transmit (pTx) cardiac TEM array was devised, using piezoelectric actuators, power monitoring equipment and control software. The reproducibility and performance of the system were tested and the power responses of the coil elements were profiled. An automated optimization method was devised and evaluated. Results The time required to tune an eight-element pTx cardiac RF array was reduced from a mean of 30 min to less than 10 min with the use of this system. Conclusion Piezoelectric actuators are an attractive means of tuning RF coil arrays to yield more efficient B1 transmission into the subject. An automated mechanism for tuning these elements provides a practical solution for cardiac imaging at UHF, bringing this technology closer to clinical use. Magn Reson Med 73:2390–2397, 2015. © 2014 The Authors. Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine. PMID:24986525

  13. Fine-Tuning Medium-of-Instruction Policy in Hong Kong: Acquisition of Language and Content-Based Subject Knowledge

    ERIC Educational Resources Information Center

    Poon, Anita Y. K.; Lau, Connie M. Y.

    2016-01-01

    Facing a dramatic decline in English standards over the past decade, the Hong Kong Government introduced the "Fine-tuning Medium of Instruction (MOI) policy" in 2010 to address the grievances arising from different sectors in the community. Integrating content and language has become popular in second/foreign language teaching in recent…

  14. Fine-Tuning Medium-of-Instruction Policy in Hong Kong: Acquisition of Language and Content-Based Subject Knowledge

    ERIC Educational Resources Information Center

    Poon, Anita Y. K.; Lau, Connie M. Y.

    2016-01-01

    Facing a dramatic decline in English standards over the past decade, the Hong Kong Government introduced the "Fine-tuning Medium of Instruction (MOI) policy" in 2010 to address the grievances arising from different sectors in the community. Integrating content and language has become popular in second/foreign language teaching in recent…

  15. Graphene-based fine-tunable optical delay line for optical beamforming in phased-array antennas.

    PubMed

    Tatoli, Teresa; Conteduca, Donato; Dell'Olio, Francesco; Ciminelli, Caterina; Armenise, Mario N

    2016-06-01

    The design of an integrated graphene-based fine-tunable optical delay line on silicon nitride for optical beamforming in phased-array antennas is reported. A high value of the optical delay time (τg=920  ps) together with a compact footprint (4.15  mm2) and optical loss <27  dB make this device particularly suitable for highly efficient steering in active phased-array antennas. The delay line includes two graphene-based Mach-Zehnder interferometer switches and two vertically stacked microring resonators between which a graphene capacitor is placed. The tuning range is obtained by varying the value of the voltage applied to the graphene electrodes, which controls the optical path of the light propagation and therefore the delay time. The graphene provides a faster reconfigurable time and low values of energy dissipation. Such significant advantages, together with a negligible beam-squint effect, allow us to overcome the limitations of conventional RF beamformers. A highly efficient fine-tunable optical delay line for the beamsteering of 20 radiating elements up to ±20° in the azimuth direction of a tile in a phased-array antenna of an X-band synthetic aperture radar has been designed.

  16. Automated SQUID tuning procedure for kilo-pixel arrays of TES bolometers on the Atacama Cosmology Telescope

    NASA Astrophysics Data System (ADS)

    Battistelli, E. S.; Amiri, M.; Burger, B.; Devlin, M. J.; Dicker, S. R.; Doriese, W. B.; Dünner, R.; Fisher, R. P.; Fowler, J. W.; Halpern, M.; Hasselfield, M.; Hilton, G. C.; Hincks, A. D.; Irwin, K. D.; Kaul, M.; Klein, J.; Knotek, S.; Lau, J. M.; Limon, M.; Marriage, T. A.; Niemack, M. D.; Page, L.; Reintsema, C. D.; Staggs, S. T.; Swetz, D. S.; Switzer, E. R.; Thornton, R. J.; Zhao, Y.

    2008-07-01

    The Atacama Cosmology Telescope observes the Cosmic Microwave Background with arcminute resolution from the Atacama desert in Chile. For the first observing season one array of 32 x 32 Transition Edge Sensor (TES) bolometers was installed in the primary ACT receiver, the Millimeter Bolometer Array Camera (MBAC). In the next season, three independent arrays working at 145, 220 and 280 GHz will be installed in MBAC. The three bolometer arrays are each coupled to a time-domain multiplexer developed at the National Institute of Standard and Technology, Boulder, which comprises three stages of superconducting quantum interference devices (SQUIDs). The arrays and multiplexers are read-out and controlled by the Multi Channel Electronics (MCE) developed at the University of British Columbia, Vancouver. A number of experiments plan to use the MCE as read-out electronics and thus the procedure for tuning the three stage SQUID system is of general interest. Here we describe the automated array tuning procedures and algorithms we have developed. During array tuning, the SQUIDs are biased near their critical currents. SQUID feedback currents and lock points are selected to maximize linearity, dynamic range, and gain of the SQUID response curves. Our automatic array characterization optimizes the tuning of all three stages of SQUIDs by selecting over 1100 parameters per array during the first observing season and over 2100 parameters during the second observing season. We discuss the timing, performance, and reliability of this array tuning procedure as well as planned and recently implemented improvements.

  17. Development of monotonic neuronal tuning in the monkey inferotemporal cortex through long-term learning of fine shape discrimination.

    PubMed

    Suzuki, Wataru; Tanaka, Keiji

    2011-02-01

    Visual expertise in discriminating fine differences among a group of similar objects can be obtained through extensive long-term training. Here we investigated the neural bases of this superior capability. The inferotemporal cortex, located at the final stage along the ventral visual pathway, was a candidate site in monkeys because cells there respond to various complex features of objects. To identify the changes that underlie the development of visual expertise in fine discrimination, we created a set of parametrically designed object stimuli and compared the stimulus selectivity of inferotemporal cells between two different training histories. One group of recordings was conducted after the monkeys had been extensively trained for fine discrimination (fine-discrimination period) and the other after the monkeys had been exposed only for coarse discrimination (coarse-discrimination period). We found that the tuning of responses recorded in the fine-discrimination period was more monotonic in the stimulus parameter space. The stimuli located at the extreme in the parameter space evoked the maximum responses in a larger proportion of cells and the direction of response decrease in the parameter space was more consistent. Moreover, the stimulus arrangement reconstructed from the responses recorded during the fine-discrimination period was more similar to the original stimulus arrangement. These results suggest that visual expertise could be based on the development, in the inferotemporal cortex, of neuronal selectivity monotonically tuned over the parameter space of the object images.

  18. Fine-tuned PEGylation of chitosan to maintain optimal siRNA-nanoplex bioactivity.

    PubMed

    Guţoaia, Andra; Schuster, Liane; Margutti, Simona; Laufer, Stefan; Schlosshauer, Burkhard; Krastev, Rumen; Stoll, Dieter; Hartmann, Hanna

    2016-06-05

    Polyethylene glycol (PEG) is a widely used modification for drug delivery systems. It reduces undesired interaction with biological components, aggregation of complexes and serves as a hydrophilic linker of ligands for targeted drug delivery. However, PEGylation can also lead to undesired changes in physicochemical characteristics of chitosan/siRNA nanoplexes and hamper gene silencing. To address this conflicting issue, PEG-chitosan copolymers were synthesized with stepwise increasing degrees of PEG substitution (1.5% to 8.0%). Subsequently formed PEG-chitosan/siRNA nanoplexes were characterized physicochemically and biologically. The results showed that small ratios of chitosan PEGylation did not affect nanoplex stability and density. However, higher PEGylation ratios reduced nanoplex size and charge, as well as cell uptake and final siRNA knockdown efficiency. Therefore, we recommend fine-tuning of PEGylation ratios to generate PEG-chitosan/siRNA delivery systems with maximum bioactivity. The degree of PEGylation for chitosan/siRNA nanoplexes should be kept low in order to maintain optimal nanoplex efficiency.

  19. Fine-tuning the ubiquitin code at DNA double-strand breaks: deubiquitinating enzymes at work

    PubMed Central

    Citterio, Elisabetta

    2015-01-01

    Ubiquitination is a reversible protein modification broadly implicated in cellular functions. Signaling processes mediated by ubiquitin (ub) are crucial for the cellular response to DNA double-strand breaks (DSBs), one of the most dangerous types of DNA lesions. In particular, the DSB response critically relies on active ubiquitination by the RNF8 and RNF168 ub ligases at the chromatin, which is essential for proper DSB signaling and repair. How this pathway is fine-tuned and what the functional consequences are of its deregulation for genome integrity and tissue homeostasis are subject of intense investigation. One important regulatory mechanism is by reversal of substrate ubiquitination through the activity of specific deubiquitinating enzymes (DUBs), as supported by the implication of a growing number of DUBs in DNA damage response processes. Here, we discuss the current knowledge of how ub-mediated signaling at DSBs is controlled by DUBs, with main focus on DUBs targeting histone H2A and on their recent implication in stem cell biology and cancer. PMID:26442100

  20. Activity-dependent relocation of the axon initial segment fine-tunes neuronal excitability.

    PubMed

    Grubb, Matthew S; Burrone, Juan

    2010-06-24

    In neurons, the axon initial segment (AIS) is a specialized region near the start of the axon that is the site of action potential initiation. The precise location of the AIS varies across and within different neuronal types, and has been linked to cells' information-processing capabilities; however, the factors determining AIS position in individual neurons remain unknown. Here we show that changes in electrical activity can alter the location of the AIS. In dissociated hippocampal cultures, chronic depolarization with high extracellular potassium moves multiple components of the AIS, including voltage-gated sodium channels, up to 17 mum away from the soma of excitatory neurons. This movement reverses when neurons are returned to non-depolarized conditions, and depends on the activation of T- and/or L-type voltage-gated calcium channels. The AIS also moved distally when we combined long-term LED (light-emitting diode) photostimulation with sparse neuronal expression of the light-activated cation channel channelrhodopsin-2; here, burst patterning of activity was successful where regular stimulation at the same frequency failed. Furthermore, changes in AIS position correlate with alterations in current thresholds for action potential spiking. Our results show that neurons can regulate the position of an entire subcellular structure according to their ongoing levels and patterns of electrical activity. This novel form of activity-dependent plasticity may fine-tune neuronal excitability during development.

  1. Drosophila SETDB1 and caspase cooperatively fine-tune cell fate determination of sensory organ precursor.

    PubMed

    Shinoda, Natsuki; Obata, Fumiaki; Zhang, Liu; Miura, Masayuki

    2016-04-01

    Drosophila produce a constant number of mechanosensory bristles called macrochaetae (MC), which develop from sensory organ precursor (SOP) cells within a proneural cluster (PNC). However, what ensures the precise determination of SOP cells remains to be elucidated. In this study, we conducted RNAi screening in PNC for genes involved in epigenetic regulation. We identified a H3K9 histone methyltransferase, SETDB1/eggless, as a regulator of SOP development. Knockdown of SETDB1 in PNC led to additional SOPs. We further tested the relationship between SETDB1 and non-apoptotic function of caspase on SOP development. Reinforcing caspase activation by heterozygous Drosophila inhibitor of apoptosis protein 1 (DIAP1) mutation rescued ectopic SOP development caused by SETDB1 knockdown. Knockdown of SETDB1, however, had little effect on caspase activity. Simultaneous loss of SETDB1 and caspase activity resulted in further increase in MC, indicating that the two components work cooperatively. Our study suggests the fine-tuning mechanisms for SOP development by epigenetic methyltransferase and non-apoptotic caspase function.

  2. Fine tuning of social integration by two myrmecophiles of the ponerine army ant, Leptogenys distinguenda.

    PubMed

    Witte, Volker; Foitzik, Susanne; Hashim, Rosli; Maschwitz, Ulrich; Schulz, Stefan

    2009-03-01

    Myrmecophiles are animals that live in close association with ants and that frequently develop elaborate mechanisms to infiltrate their well-defended host societies. We compare the social integration strategies of two myrmecophilic species, the spider, Gamasomorpha maschwitzi, and the newly described silverfish, Malayatelura ponerophila gen. n. sp. n., into colonies of the ponerine army ant, Leptogenys distinguenda (Emery) (Hymenoptera: Formicidae). Both symbionts use chemical mimicry through adoption of host cuticular hydrocarbons. Exchange experiments between L. distinguenda and an undetermined Leptogenys species demonstrate that reduced aggression toward alien ants and increased social acceptance occurred with individuals of higher chemical similarity in their cuticular hydrocarbon profiles. We found striking differences in chemical and behavioral strategies between the two myrmecophiles. Spider cuticular hydrocarbon profiles were chemically less similar to the host than silverfish profiles were. Nevertheless, spiders received significantly fewer attacks from host ants and survived longer in laboratory colonies, whereas silverfish were treated with high aggression and were killed more frequently. When discovered and confronted by the host, silverfish tended to escape and were chased aggressively, whereas spiders remained in contact with the confronting host ant until aggression ceased. Thus, spiders relied less on chemical mimicry but were nevertheless accepted more frequently by the host on the basis of behavioral mechanisms. These findings give insights into the fine tuning of social integration mechanisms and show the significance of qualitative differences among strategies.

  3. Tissue-Specific Regulation of Gibberellin Signaling Fine-Tunes Arabidopsis Iron-Deficiency Responses.

    PubMed

    Wild, Michael; Davière, Jean-Michel; Regnault, Thomas; Sakvarelidze-Achard, Lali; Carrera, Esther; Lopez Diaz, Isabel; Cayrel, Anne; Dubeaux, Guillaume; Vert, Grégory; Achard, Patrick

    2016-04-18

    Iron is an essential element for most living organisms. Plants acquire iron from the rhizosphere and have evolved different biochemical and developmental responses to adapt to a low-iron environment. In Arabidopsis, FIT encodes a basic helix-loop-helix transcription factor that activates the expression of iron-uptake genes in root epidermis upon iron deficiency. Here, we report that the gibberellin (GA)-signaling DELLA repressors contribute substantially in the adaptive responses to iron-deficient conditions. When iron availability decreases, DELLAs accumulate in the root meristem, thereby restraining root growth, while being progressively excluded from epidermal cells in the root differentiation zone. Such DELLA exclusion from the site of iron acquisition relieves FIT from DELLA-dependent inhibition and therefore promotes iron uptake. Consistent with this mechanism, expression of a non-GA-degradable DELLA mutant protein in root epidermis interferes with iron acquisition. Hence, spatial distribution of DELLAs in roots is essential to fine-tune the adaptive responses to iron availability.

  4. Fine-tuning the metallic core-shell nanostructures for plasmonic perovskite solar cells

    NASA Astrophysics Data System (ADS)

    Tang, Mingyao; Zhou, Lin; Gu, Shuai; Zhu, Weidong; Wang, Yang; Xu, Jun; Deng, Zhengtao; Yu, Tao; Lu, Zhenda; Zhu, Jia

    2016-10-01

    Plasmonic nanostructures have been widely applied in various types of solar cells for improving light absorption and therefore energy conversion efficiency. In this work, we demonstrate that Au@SiO2 core-shell nanorods with finely tuned aspect ratios are highly beneficial for the CH3NH3PbI3 perovskite solar cell, with the simultaneous enhancement of solar absorption and external quantum efficiency across a broad range of wavelength, which can contribute to the increased cross-sectional scattering and spectrally absorbing energy density. Therefore, a 16.1% improvement (from 12.4% to 14.4%) of the maximal external quantum efficiency can be achieved by such structures, accompanied with a 13.5% improvement (from 20.0 to 22.7 mA/cm2) of the maximal short-circuit current density and little improvement of the open-circuit voltage and fill factor. Our findings also provide a general guideline to design solar cell structures with thinner absorber layers and improve the absorption in other poorly light-absorbing devices like lead free perovskite solar cells as well.

  5. Metalloprotease OMA1 Fine-tunes Mitochondrial Bioenergetic Function and Respiratory Supercomplex Stability

    PubMed Central

    Bohovych, Iryna; Fernandez, Mario R.; Rahn, Jennifer J.; Stackley, Krista D.; Bestman, Jennifer E.; Anandhan, Annadurai; Franco, Rodrigo; Claypool, Steven M.; Lewis, Robert E.; Chan, Sherine S. L.; Khalimonchuk, Oleh

    2015-01-01

    Mitochondria are involved in key cellular functions including energy production, metabolic homeostasis, and apoptosis. Normal mitochondrial function is preserved by several interrelated mechanisms. One mechanism – intramitochondrial quality control (IMQC) – is represented by conserved proteases distributed across mitochondrial compartments. Many aspects and physiological roles of IMQC components remain unclear. Here, we show that the IMQC protease Oma1 is required for the stability of the respiratory supercomplexes and thus balanced and tunable bioenergetic function. Loss of Oma1 activity leads to a specific destabilization of respiratory supercomplexes and consequently to unbalanced respiration and progressive respiratory decline in yeast. Similarly, experiments in cultured Oma1-deficient mouse embryonic fibroblasts link together impeded supercomplex stability and inability to maintain proper respiration under conditions that require maximal bioenergetic output. Finally, transient knockdown of OMA1 in zebrafish leads to impeded bioenergetics and morphological defects of the heart and eyes. Together, our biochemical and genetic studies in yeast, zebrafish and mammalian cells identify a novel and conserved physiological role for Oma1 protease in fine-tuning of respiratory function. We suggest that this unexpected physiological role is important for cellular bioenergetic plasticity and may contribute to Oma1-associated disease phenotypes in humans. PMID:26365306

  6. Lidar Applications for Fine Tuning Forest Inventory Estimates in the Nonforest and Understory Carbon Pools

    NASA Astrophysics Data System (ADS)

    Johnson, K. D.; Birdsey, R.; Huang, W.; Dolan, K. A.; Finley, A. O.; Domke, G. M.; Russell, M.; ONeil-Dunne, J.; Dubayah, R.; Hurtt, G. C.

    2016-12-01

    The Forest Inventory and Analysis (FIA) program within the USDA Forest Service maintains permanent sample plots that provide valuable data for robust and consistent estimates of major forest carbon pools in the United States, and are currently used for official estimates to the greenhouse gas inventories compiled by EPA and reported to the UNFCCC and other entities. Nonetheless, there exist some carbon accounting gaps and indirectly measured pools that may be improved. Carbon in both "trees outside forest" and the understory is not currently measured directly in FIA plots. Understory carbon is predicted as a portion of total aboveground biomass, rather than from measurements of shrub, forbs or graminoid mass. In the current study, lidar data obtained at FIA plot locations was used to predict carbon in "trees outside forest" and the understory in the forests of Pennsylvania, Maryland, and Delaware, USA, potentially improving current estimates. Results indicate that carbon in "trees outside forests" represent a significant and under-estimated stock in this region. Understory carbon remains difficult to quantify at the plot level, but meaningful relationships with lidar canopy height (a proxy for stand succession) suggest that reliable population estimates may be aided by lidar data. Fine tuning these estimates is important, not only for improving the accuracy of estimates, but also for reconciling estimates with independently created forest carbon maps.

  7. Hypothermia Promotes Interleukin-22 Expression and Fine-Tunes Its Biological Activity.

    PubMed

    Chichelnitskiy, Evgeny; Himmelseher, Britta; Bachmann, Malte; Pfeilschifter, Josef; Mühl, Heiko

    2017-01-01

    Disturbed homeostasis as a result of tissue stress can provoke leukocyte responses enabling recovery. Since mild hypothermia displays specific clinically relevant tissue-protective properties and interleukin (IL)-22 promotes healing at host/environment interfaces, effects of lowered ambient temperature on IL-22 were studied. We demonstrate that a 5-h exposure of endotoxemic mice to 4°C reduces body temperature by 5.0° and enhances splenic and colonic il22 gene expression. In contrast, tumor necrosis factor-α and IL-17A were not increased. In vivo data on IL-22 were corroborated using murine splenocytes and human peripheral blood mononuclear cells (PBMC) cultured upon 33°C and polyclonal T cell activation. Upregulation by mild hypothermia of largely T-cell-derived IL-22 in PBMC required monocytes and associated with enhanced nuclear T-cell nuclear factor of activated T cells (NFAT)-c2. Notably, NFAT antagonism by cyclosporin A or FK506 impaired IL-22 upregulation at normothermia and entirely prevented its enhanced expression upon hypothermic culture conditions. Data suggest that intact NFAT signaling is required for efficient IL-22 induction upon normothermic and hypothermic conditions. Hypothermia furthermore boosted early signal transducer and activator of transcription 3 activation by IL-22 and shaped downstream gene expression in epithelial-like cells. Altogether, data indicate that hypothermia supports and fine-tunes IL-22 production/action, which may contribute to regulatory properties of low ambient temperature.

  8. Fine-tuned Remote Laser Welding of Aluminum to Copper with Local Beam Oscillation

    NASA Astrophysics Data System (ADS)

    Fetzer, Florian; Jarwitz, Michael; Stritt, Peter; Weber, Rudolf; Graf, Thomas

    Local beam oscillation in remote laser welding of aluminum to copper was investigated. Sheets of 1 mm thickness were welded in overlap configuration with aluminum as top material. The laser beam was scanned in a sinusoidal mode perpendicular to the direction of feed and the influence of the oscillation parameters frequency and amplitude on the weld geometry was investigated. Scanning frequencies up to 1 kHz and oscillation amplitudes in the range from 0.25 mm to 1 mm were examined. Throughout the experiments the laser power and the feed rate were kept constant. A decrease of welding depth with amplitude and frequency is found. The scanning amplitude had a strong influence and allowed coarse setting of the welding depth into the lower material, while the frequency allowed fine tuning in the order of 10% of the obtained depth. The oscillation parameters were found to act differently on the aluminum sheet compared to copper sheet regarding the amount of fused material. It is possible to influence the geometry of the fused zones separately for both sheets. Therefore the average composition in the weld can be set with high precision via the oscillation parameters. A setting of the generated intermetallics in the weld zone is possible without adjustment of laser power and feed rate.

  9. To blink or not to blink: fine cognitive tuning of the defensive peripersonal space.

    PubMed

    Sambo, C F; Forster, B; Williams, S C; Iannetti, G D

    2012-09-12

    The blink reflex elicited by the electrical stimulation of the median nerve at the wrist [hand blink reflex (HBR)] is a subcortical, defensive response that is enhanced when the stimulated hand is inside the peripersonal space of the face. Such enhancement results from a tonic, top-down modulation of the excitability of the brainstem interneurons mediating the HBR. Here we aim to (1) characterize the somatotopical specificity of this top-down modulation and investigate its dependence on (2) cognitive expectations and (3) the presence of objects protecting the face, in healthy humans. Experiment 1 showed that the somatotopical specificity of the HBR enhancement is partially homosegmental, i.e., it is greater for the HBR elicited by the stimulation of the hand near the face compared with the other hand, always kept far from the face. Experiment 2 showed that the HBR is enhanced only when participants expect to receive stimuli on the hand close to the face and is thus strongly dependent on cognitive expectations. Experiment 3 showed that the HBR enhancement by hand-face proximity is suppressed when a thin wooden screen is placed between the participants' face and their hand. Thus, the screen reduces the extension of the defensive peripersonal space, so that the hand is never inside the peripersonal space of the face, even in the "near" condition. Together, these findings indicate a fine somatotopical and cognitive tuning of the excitability of brainstem circuits subserving the HBR, whose strength is adjusted depending on the context in a purposeful manner.

  10. Fine-tuning somatostatin receptor signalling by agonist-selective phosphorylation and dephosphorylation: IUPHAR Review 5

    PubMed Central

    Schulz, Stefan; Lehmann, Andreas; Kliewer, Andrea; Nagel, Falko

    2014-01-01

    The biological actions of somatostatin are mediated by a family of five GPCRs, named sst1 to sst5. Somatostatin receptors exhibit equally high-binding affinities to their natural ligand somatostatin-14 and largely overlapping distributions. The overexpression of somatostatin receptors in human tumours is the molecular basis for diagnostic and therapeutic application of the stable somatostatin analogues octreotide, lanreotide and pasireotide. The efficiency of somatostatin receptor signalling is tightly regulated and ultimately limited by the coordinated phosphorylation and dephosphorylation of intracellular carboxyl-terminal serine and threonine residues. Here, we review and discuss recent progress in the generation and application of phosphosite-specific antibodies for human sst2 and sst5 receptors. These phosphosite-specific antibodies are unique tools to monitor the spatial and temporal dynamics of receptors phosphorylation and dephosphorylation. Using a combined approach of phosphosite-specific antibodies and siRNA knock-down screening, relevant kinases and phosphatases were identified. Emerging evidence suggests distinct mechanisms of agonist-selective fine-tuning for individual somatostatin receptors. The recently uncovered differences in phosphorylation and dephosphorylation of these receptors may hence be of physiological significance in mediating responses to acute, persistent or repeated stimuli in a variety of target tissues. PMID:24328848

  11. Statistical-Mechanical Analysis of Pre-training and Fine Tuning in Deep Learning

    NASA Astrophysics Data System (ADS)

    Ohzeki, Masayuki

    2015-03-01

    In this paper, we present a statistical-mechanical analysis of deep learning. We elucidate some of the essential components of deep learning — pre-training by unsupervised learning and fine tuning by supervised learning. We formulate the extraction of features from the training data as a margin criterion in a high-dimensional feature-vector space. The self-organized classifier is then supplied with small amounts of labelled data, as in deep learning. Although we employ a simple single-layer perceptron model, rather than directly analyzing a multi-layer neural network, we find a nontrivial phase transition that is dependent on the number of unlabelled data in the generalization error of the resultant classifier. In this sense, we evaluate the efficacy of the unsupervised learning component of deep learning. The analysis is performed by the replica method, which is a sophisticated tool in statistical mechanics. We validate our result in the manner of deep learning, using a simple iterative algorithm to learn the weight vector on the basis of belief propagation.

  12. Fungal Endophytes as a Metabolic Fine-Tuning Regulator for Wine Grape

    PubMed Central

    Huang, Zhi-Yu; Yang, Wei-Xi; Zhang, Han-Bo; Huang, Li-Hua; Ren, An-Yun; Shan, Hui

    2016-01-01

    Endophytes proved to exert multiple effects on host plants, including growth promotion, stress resistance. However, whether endophytes have a role in metabolites shaping of grape has not been fully understood. Eight endophytic fungal strains which originally isolated from grapevines were re-inoculated to field-grown grapevines in this study, and their effects on both leaves and berries of grapevines at maturity stage were assessed, with special focused on secondary metabolites and antioxidant activities. High-density inoculation of all these endophytic fungal strains modified the physio-chemical status of grapevine to different degrees. Fungal inoculations promoted the content of reducing sugar (RS), total flavonoids (TF), total phenols (TPh), trans-resveratrol (Res) and activities of phenylalanine ammonia-lyase (PAL), in both leaves and berries of grapevine. Inoculation of endophytic fungal strains, CXB-11 (Nigrospora sp.) and CXC-13 (Fusarium sp.) conferred greater promotion effects in grape metabolic re-shaping, compared to other used fungal strains. Additionally, inoculation of different strains of fungal endophytes led to establish different metabolites patterns of wine grape. The work implies the possibility of using endophytic fungi as fine-tuning regulator to shape the quality and character of wine grape. PMID:27656886

  13. Finely tuned response of native prey to an invasive predator in a freshwater system.

    PubMed

    Bourdeau, Paul E; Pangle, Kevin L; Reed, Emily M; Peacor, Scott D

    2013-07-01

    Lack of shared evolutionary history reduces the expectation that native prey will detect and respond to invasive predators. Four mechanisms may explain the adaptive response that is nevertheless seen in various systems: prey may perceive the invasive predator through cue similarity with preexisting predators, cues of conspecifics eaten by the invasive predator, a learned response based on experience with the invasive predator (e.g., cue association), and cues from the invasive predator that are specific to it. We performed laboratory experiments in which zooplankton (Daphnia mendotae) responded adaptively to the zooplanktivore Bythotrephes longimanus (migrating downward), showed no response to taxonomically similar predatory cladocerans, and responded adaptively to more taxonomically distant native fish (migrating downward) and native shrimp (migrating upward). Conspecific cues associated with Bythotrephes predation actually reduced the response of D. mendotae to Bythotrephes. Combined with previous experiments that rule out learning, our experiments rule out the first three mechanisms above, demonstrating that D. mendotae respond to cues specific to and produced directly by Bythotrephes. This finely tuned response may be retained from an ancestral species that coevolved with Bythotrephes in its native range, or may have rapidly evolved due to strong selection by the invasive predator.

  14. Redirecting abiraterone metabolism to fine-tune prostate cancer anti-androgen therapy.

    PubMed

    Li, Zhenfei; Alyamani, Mohammad; Li, Jianneng; Rogacki, Kevin; Abazeed, Mohamed; Upadhyay, Sunil K; Balk, Steven P; Taplin, Mary-Ellen; Auchus, Richard J; Sharifi, Nima

    2016-05-26

    Abiraterone blocks androgen synthesis and prolongs survival in patients with castration-resistant prostate cancer, which is otherwise driven by intratumoral androgen synthesis. Abiraterone is metabolized in patients to Δ(4)-abiraterone (D4A), which has even greater anti-tumour activity and is structurally similar to endogenous steroidal 5α-reductase substrates, such as testosterone. Here, we show that D4A is converted to at least three 5α-reduced and three 5β-reduced metabolites in human serum. The initial 5α-reduced metabolite, 3-keto-5α-abiraterone, is present at higher concentrations than D4A in patients with prostate cancer taking abiraterone, and is an androgen receptor agonist, which promotes prostate cancer progression. In a clinical trial of abiraterone alone, followed by abiraterone plus dutasteride (a 5α-reductase inhibitor), 3-keto-5α-abiraterone and downstream metabolites were depleted by the addition of dutasteride, while D4A concentrations rose, showing that dutasteride effectively blocks production of a tumour-promoting metabolite and permits D4A accumulation. Furthermore, dutasteride did not deplete the three 5β-reduced metabolites, which were also clinically detectable, demonstrating the specific biochemical effects of pharmacological 5α-reductase inhibition on abiraterone metabolism. Our findings suggest a previously unappreciated and biochemically specific method of clinically fine-tuning abiraterone metabolism to optimize therapy.

  15. Community-integrated omics links dominance of a microbial generalist to fine-tuned resource usage

    PubMed Central

    Muller, Emilie E. L.; Pinel, Nicolás; Laczny, Cédric C.; Hoopmann, Michael R.; Narayanasamy, Shaman; Lebrun, Laura A.; Roume, Hugo; Lin, Jake; May, Patrick; Hicks, Nathan D.; Heintz-Buschart, Anna; Wampach, Linda; Liu, Cindy M.; Price, Lance B.; Gillece, John D.; Guignard, Cédric; Schupp, James M.; Vlassis, Nikos; Baliga, Nitin S.; Moritz, Robert L.; Keim, Paul S.; Wilmes, Paul

    2014-01-01

    Microbial communities are complex and dynamic systems that are primarily structured according to their members’ ecological niches. To investigate how niche breadth (generalist versus specialist lifestyle strategies) relates to ecological success, we develop and apply an integrative workflow for the multi-omic analysis of oleaginous mixed microbial communities from a biological wastewater treatment plant. Time- and space-resolved coupled metabolomic and taxonomic analyses demonstrate that the community-wide lipid accumulation phenotype is associated with the dominance of the generalist bacterium Candidatus Microthrix spp. By integrating population-level genomic reconstructions (reflecting fundamental niches) with transcriptomic and proteomic data (realised niches), we identify finely tuned gene expression governing resource usage by Candidatus Microthrix parvicella over time. Moreover, our results indicate that the fluctuating environmental conditions constrain the accumulation of genetic variation in Candidatus Microthrix parvicella likely due to fitness trade-offs. Based on our observations, niche breadth has to be considered as an important factor for understanding the evolutionary processes governing (microbial) population sizes and structures in situ. PMID:25424998

  16. Core formation in dwarf haloes with self-interacting dark matter: no fine-tuning necessary

    NASA Astrophysics Data System (ADS)

    Elbert, Oliver D.; Bullock, James S.; Garrison-Kimmel, Shea; Rocha, Miguel; Oñorbe, Jose; Peter, Annika H. G.

    2015-10-01

    We investigate the effect of self-interacting dark matter (SIDM) on the density profiles of Vmax ≃ 40km s-1 isolated dwarf dark matter haloes - the scale of relevance for the too big to fail problem (TBTF) - using very high resolution cosmological zoom simulations. Each halo has millions of particles within its virial radius. We find that SIDM models with cross-sections per unit mass spanning the range σ/m = 0.5-50 cm2 g-1 alleviate TBTF and produce constant-density cores of size 300-1000 pc, comparable to the half-light radii of M⋆ ˜ 105 - 7 M⊙ dwarfs. The largest, lowest density cores develop for cross-sections in the middle of this range, σ/m ˜ 5-10 cm2 g-1. Our largest SIDM cross-section run (σ/m = 50 cm2 g-1) develops a slightly denser core owing to mild core-collapse behaviour, but it remains less dense than the cold dark matter case and retains a constant-density core profile. Our work suggests that SIDM cross-sections as large or larger than 50 cm2 g-1 remain viable on velocity scales of dwarf galaxies (vrms ˜ 40 km s-1). The range of SIDM cross-sections that alleviate TBTF and the cusp/core problem spans at least two orders of magnitude and therefore need not be particularly fine-tuned.

  17. Metabolomic profiling reveals a finely tuned, starvation-induced metabolic switch in Trypanosoma cruzi epimastigotes.

    PubMed

    Barisón, María Julia; Rapado, Ludmila Nakamura; Merino, Emilio F; Furusho Pral, Elizabeth Mieko; Mantilla, Brian Suarez; Marchese, Letícia; Nowicki, Cristina; Silber, Ariel Mariano; Cassera, Maria Belen

    2017-05-26

    Trypanosoma cruzi, the etiological agent of Chagas disease, is a protozoan parasite with a complex life cycle involving a triatomine insect and mammals. Throughout its life cycle, the T. cruzi parasite faces several alternating events of cell division and cell differentiation in which exponential and stationary growth phases play key biological roles. It is well accepted that arrest of the cell division in the epimastigote stage, both in the midgut of the triatomine insect and in vitro, is required for metacyclogenesis, and it has been previously shown that the parasites change the expression profile of several proteins when entering this quiescent stage. However, little is known about the metabolic changes that epimastigotes undergo before they develop into the metacyclic trypomastigote stage. We applied targeted metabolomics to measure the metabolic intermediates in the most relevant pathways for energy metabolism and oxidative imbalance in exponentially growing and stationary growth-arrested epimastigote parasites. We show for the first time that T. cruzi epimastigotes transitioning from the exponential to the stationary phase exhibit a finely tuned adaptive metabolic mechanism that enables switching from glucose to amino acid consumption, which is more abundant in the stationary phase. This metabolic plasticity appears to be crucial for survival of the T. cruzi parasite in the myriad different environmental conditions to which it is exposed during its life cycle. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

  18. Neuronal Target Identification Requires AHA-1-Mediated Fine-Tuning of Wnt Signaling in C. elegans

    PubMed Central

    Zhang, Jingyan; Li, Xia; Jevince, Angela R.; Guan, Liying; Wang, Jiaming; Hall, David H.; Huang, Xun; Ding, Mei

    2013-01-01

    Electrical synaptic transmission through gap junctions is a vital mode of intercellular communication in the nervous system. The mechanism by which reciprocal target cells find each other during the formation of gap junctions, however, is poorly understood. Here we show that gap junctions are formed between BDU interneurons and PLM mechanoreceptors in C. elegans and the connectivity of BDU with PLM is influenced by Wnt signaling. We further identified two PAS-bHLH family transcription factors, AHA-1 and AHR-1, which function cell-autonomously within BDU and PLM to facilitate the target identification process. aha-1 and ahr-1 act genetically upstream of cam-1. CAM-1, a membrane-bound receptor tyrosine kinase, is present on both BDU and PLM cells and likely serves as a Wnt antagonist. By binding to a cis-regulatory element in the cam-1 promoter, AHA-1 enhances cam-1 transcription. Our study reveals a Wnt-dependent fine-tuning mechanism that is crucial for mutual target cell identification during the formation of gap junction connections. PMID:23825972

  19. Calmodulin-mediated signal transduction pathways in Arabidopsis are fine-tuned by methylation.

    PubMed

    Banerjee, Joydeep; Magnani, Roberta; Nair, Meera; Dirk, Lynnette M; DeBolt, Seth; Maiti, Indu B; Houtz, Robert L

    2013-11-01

    Calmodulin N-methyltransferase (CaM KMT) is an evolutionarily conserved enzyme in eukaryotes that transfers three methyl groups to a highly conserved lysyl residue at position 115 in calmodulin (CaM). We sought to elucidate whether the methylation status of CaM plays a role in CaM-mediated signaling pathways by gene expression analyses of CaM KMT and phenotypic characterization of Arabidopsis thaliana lines wherein CaM KMT was overexpressed (OX), partially silenced, or knocked out. CaM KMT was expressed in discreet spatial and tissue-specific patterns, most notably in root tips, floral buds, stamens, apical meristems, and germinating seeds. Analysis of transgenic plants with genetic dysfunction in CaM KMT revealed a link between the methylation status of CaM and root length. Plants with suppressed CaM methylation had longer roots and CaM KMT OX lines had shorter roots than wild type (Columbia-0). CaM KMT was also found to influence the root radial developmental program. Protein microarray analyses revealed a number of proteins with specificity for methylated forms of CaM, providing candidate functional intermediates between the observed phenotypes and the target pathways. This work demonstrates that the functionality of the large CaM family in plants is fine-tuned by an overarching methylation mechanism.

  20. Calmodulin-Mediated Signal Transduction Pathways in Arabidopsis Are Fine-Tuned by Methylation[W

    PubMed Central

    Banerjee, Joydeep; Magnani, Roberta; Nair, Meera; Dirk, Lynnette M.; DeBolt, Seth; Maiti, Indu B.; Houtz, Robert L.

    2013-01-01

    Calmodulin N-methyltransferase (CaM KMT) is an evolutionarily conserved enzyme in eukaryotes that transfers three methyl groups to a highly conserved lysyl residue at position 115 in calmodulin (CaM). We sought to elucidate whether the methylation status of CaM plays a role in CaM-mediated signaling pathways by gene expression analyses of CaM KMT and phenotypic characterization of Arabidopsis thaliana lines wherein CaM KMT was overexpressed (OX), partially silenced, or knocked out. CaM KMT was expressed in discreet spatial and tissue-specific patterns, most notably in root tips, floral buds, stamens, apical meristems, and germinating seeds. Analysis of transgenic plants with genetic dysfunction in CaM KMT revealed a link between the methylation status of CaM and root length. Plants with suppressed CaM methylation had longer roots and CaM KMT OX lines had shorter roots than wild type (Columbia-0). CaM KMT was also found to influence the root radial developmental program. Protein microarray analyses revealed a number of proteins with specificity for methylated forms of CaM, providing candidate functional intermediates between the observed phenotypes and the target pathways. This work demonstrates that the functionality of the large CaM family in plants is fine-tuned by an overarching methylation mechanism. PMID:24285794

  1. Maternal expression of communicative intentions and pragmatic fine tuning in early infancy.

    PubMed

    Rivero, Magda

    2010-12-01

    This study focuses on pragmatic characteristics of infant-directed speech and pragmatic fine tuning during the first 18 months of life. The subjects of the study were a mother-child dyad involved in a longitudinal/observational study in a familial context. Audiovisual recordings were transcribed according to the conventions of the Child Language Data Exchange System (MacWhinney, 2000; MacWhinney & Snow, 1990). The Ninio and Wheeler's (1988) system for coding communicative intentions was adapted. The results of this research show that most of the communicative exchanges identified at 14, 20 and 32 months by Snow, Pan, Imbens-Bailey, and Herman (1996) appear in mother-child interaction from the beginning, while other communicative interchanges appear later. With respect to speech acts, the results highlight, from an early age, the general tendencies discussed by Snow et al. and some novelties. Interestingly, changes in some pragmatic measures were identified around 8 months of age, and the appearance of new communicative interchanges also took place around this age. These changes are interpreted as maternal adjustments to the child's communicative competence.

  2. Tuning Piezo ion channels to detect molecular-scale movements relevant for fine touch

    PubMed Central

    Poole, Kate; Herget, Regina; Lapatsina, Liudmila; Ngo, Ha-Duong; Lewin, Gary R.

    2014-01-01

    In sensory neurons, mechanotransduction is sensitive, fast and requires mechanosensitive ion channels. Here we develop a new method to directly monitor mechanotransduction at defined regions of the cell-substrate interface. We show that molecular-scale (~13 nm) displacements are sufficient to gate mechanosensitive currents in mouse touch receptors. Using neurons from knockout mice, we show that displacement thresholds increase by one order of magnitude in the absence of stomatin-like protein 3 (STOML3). Piezo1 is the founding member of a class of mammalian stretch-activated ion channels, and we show that STOML3, but not other stomatin-domain proteins, brings the activation threshold for Piezo1 and Piezo2 currents down to ~10 nm. Structure–function experiments localize the Piezo modulatory activity of STOML3 to the stomatin domain, and higher-order scaffolds are a prerequisite for function. STOML3 is the first potent modulator of Piezo channels that tunes the sensitivity of mechanically gated channels to detect molecular-scale stimuli relevant for fine touch. PMID:24662763

  3. Tuning Piezo ion channels to detect molecular-scale movements relevant for fine touch

    NASA Astrophysics Data System (ADS)

    Poole, Kate; Herget, Regina; Lapatsina, Liudmila; Ngo, Ha-Duong; Lewin, Gary R.

    2014-03-01

    In sensory neurons, mechanotransduction is sensitive, fast and requires mechanosensitive ion channels. Here we develop a new method to directly monitor mechanotransduction at defined regions of the cell-substrate interface. We show that molecular-scale (~13 nm) displacements are sufficient to gate mechanosensitive currents in mouse touch receptors. Using neurons from knockout mice, we show that displacement thresholds increase by one order of magnitude in the absence of stomatin-like protein 3 (STOML3). Piezo1 is the founding member of a class of mammalian stretch-activated ion channels, and we show that STOML3, but not other stomatin-domain proteins, brings the activation threshold for Piezo1 and Piezo2 currents down to ~10 nm. Structure-function experiments localize the Piezo modulatory activity of STOML3 to the stomatin domain, and higher-order scaffolds are a prerequisite for function. STOML3 is the first potent modulator of Piezo channels that tunes the sensitivity of mechanically gated channels to detect molecular-scale stimuli relevant for fine touch.

  4. Tuning Piezo ion channels to detect molecular-scale movements relevant for fine touch.

    PubMed

    Poole, Kate; Herget, Regina; Lapatsina, Liudmila; Ngo, Ha-Duong; Lewin, Gary R

    2014-03-24

    In sensory neurons, mechanotransduction is sensitive, fast and requires mechanosensitive ion channels. Here we develop a new method to directly monitor mechanotransduction at defined regions of the cell-substrate interface. We show that molecular-scale (~13 nm) displacements are sufficient to gate mechanosensitive currents in mouse touch receptors. Using neurons from knockout mice, we show that displacement thresholds increase by one order of magnitude in the absence of stomatin-like protein 3 (STOML3). Piezo1 is the founding member of a class of mammalian stretch-activated ion channels, and we show that STOML3, but not other stomatin-domain proteins, brings the activation threshold for Piezo1 and Piezo2 currents down to ~10 nm. Structure-function experiments localize the Piezo modulatory activity of STOML3 to the stomatin domain, and higher-order scaffolds are a prerequisite for function. STOML3 is the first potent modulator of Piezo channels that tunes the sensitivity of mechanically gated channels to detect molecular-scale stimuli relevant for fine touch.

  5. Fibroblast Growth Factor 21 Protects against Atherosclerosis via Fine-Tuning the Multiorgan Crosstalk

    PubMed Central

    Jin, Leigang; Lin, Zhuofeng

    2016-01-01

    Fibroblast growth factor 21 (FGF21) is a metabolic hormone with pleiotropic effects on energy metabolism and insulin sensitivity. Besides its antiobese and antidiabetic activity, FGF21 also possesses the protective effects against atherosclerosis. Circulating levels of FGF21 are elevated in patients with atherosclerosis, macrovascular and microvascular complications of diabetes, possibly due to a compensatory upregulation. In apolipoprotein E-deficient mice, formation of atherosclerotic plaques is exacerbated by genetic depletion of FGF21, but is attenuated upon replenishment with recombinant FGF21. However, the blood vessel is not the direct target of FGF21, and the antiatherosclerotic activity of FGF21 is attributed to its actions in adipose tissues and liver. In adipocytes, FGF21 promotes secretion of adiponectin, which in turn acts directly on blood vessels to reduce endothelial dysfunction, inhibit proliferation of smooth muscle cells and block conversion of macrophages to foam cells. Furthermore, FGF21 suppresses cholesterol biosynthesis and attenuates hypercholesterolemia by inhibiting the transcription factor sterol regulatory element-binding protein-2 in hepatocytes. The effects of FGF21 on elevation of adiponectin and reduction of hypercholesterolemia are also observed in a phase-1b clinical trial in patients with obesity and diabetes. Therefore, FGF21 exerts its protection against atherosclerosis by fine-tuning the interorgan crosstalk between liver, brain, adipose tissue, and blood vessels. PMID:26912152

  6. Redirecting abiraterone metabolism to fine tune prostate cancer anti-androgen therapy

    PubMed Central

    Li, Zhenfei; Alyamani, Mohammad; Li, Jianneng; Rogacki, Kevin; Abazeed, Mohamed; Upadhyay, Sunil K.; Balk, Steven P.; Taplin, Mary-Ellen; Auchus, Richard J.; Sharifi, Nima

    2016-01-01

    Abiraterone blocks androgen synthesis and prolongs survival in castration-resistant prostate cancer, which is otherwise driven by intratumoral androgen synthesis1,2. Abiraterone is metabolized in patients to D4A, which has even greater anti-tumor activity and structural similarities to endogenous steroidal 5α-reductase substrates, such as testosterone3. Here, we show that D4A is converted to at least 3 5α-reduced and 3 5β-reduced metabolites. The initial 5α-reduced metabolite, 3-keto-5α-abi, is more abundant than D4A in patients with prostate cancer taking abiraterone, and is an androgen receptor (AR) agonist, which promotes prostate cancer progression. In a clinical trial of abiraterone alone, followed by abiraterone plus dutasteride (a 5α-reductase inhibitor), 3-keto-5α-abi and downstream metabolites are depleted, while D4A concentrations rise, effectively blocking production of a tumor-promoting metabolite and permitting D4A accumulation. Furthermore, dutasteride does not deplete three 5β-reduced metabolites, which were also clinically detectable, demonstrating the specific biochemical effects of pharmacologic 5α-reductase inhibition on abiraterone metabolism. Our findings suggest a previously unappreciated and biochemically specific method of clinically fine-tuning abiraterone metabolism to optimize therapy. PMID:27225130

  7. Fine-tuning of whispering gallery modes in on-chip silica microdisk resonators within a full spectral range

    NASA Astrophysics Data System (ADS)

    Henze, Rico; Pyrlik, Christoph; Thies, Andreas; Ward, Jonathan M.; Wicht, Andreas; Benson, Oliver

    2013-01-01

    We investigate an efficient method for fine-tuning whispering gallery mode resonances in disk-type silica microresonators to reach an arbitrary frequency within the free spectral range of the system. This method is based on a post-production hydrofluoric acid etching process to precisely resize the radius of such microresonators. We show the effectiveness of this approach by tuning their resonance frequency within 10 GHz of specific hydrogen cyanide reference lines (P16, P18). This technique allows for simple and exact matching of narrow-linewidth lasers or spectroscopic lines with the high-Q resonances of on-chip silica microresonators.

  8. Measured and calculated acoustic attenuation rates of tuned resonator arrays for two surface impedance distribution models with flow

    NASA Technical Reports Server (NTRS)

    Parrott, Tony L.; Abrahamson, A. Louis; Jones, Michael G.

    1988-01-01

    An experiment was performed to validate two analytical models for predicting low frequency attenuation of duct liner configurations built from an array of seven resonators that could be individually tuned via adjustable cavity depths. These analytical models had previously been developed for high frequency aero-engine inlet duct liner design. In the low frequency application, the liner surface impedance distribution is unavoidably spatially varying by virtue of available fabrication techniques. The characteristic length of this spatial variation may be a significant fraction of the acoustic wavelength. Comparison of measured and predicted attenuation rates and transmission losses for both modal decomposition and finite element propagation models were in good to excellent agreement for a test frequency range that included the first and second cavity resonance frequencies. This was true for either of two surface impedance distribution modeling procedures used to simplify the impedance boundary conditions. In the presence of mean flow, measurements revealed a fine scale structure of acoustic hot spots in the attenuation and phase profiles. These details were accurately predicted by the finite element model. Since no impedance changes due to mean flow were assumed, it is concluded that this fine scale structure was due to convective effects of the mean flow interacting with the surface impedance nonuniformities.

  9. Photoassisted photoluminescence fine-tuning of gold nanodots through free radical-mediated ligand-assembly

    NASA Astrophysics Data System (ADS)

    Tseng, Yu-Ting; Cherng, Rochelle; Harroun, Scott G.; Yuan, Zhiqin; Lin, Tai-Yuan; Wu, Chien-Wei; Chang, Huan-Tsung; Huang, Chih-Ching

    2016-05-01

    In this study, we have developed a simple photoassisted ligand assembly to fine-tune the photoluminescence (PL) of (11-mercaptoundecyl)-N,N,N-trimethylammonium bromide-capped gold nanodots (11-MUTAB-Au NDs). The 11-MUTAB-Au NDs (size: ca. 1.8 nm), obtained from the reaction of gold nanoparticles (ca. 3 nm) and 11-MUTAB, exhibited weak, near-infrared (NIR) PL at 700 nm with a quantum yield (QY) of 0.37% upon excitation at 365 nm. The PL QY of the Au NDs increased to 11.43% after reaction with 11-mercaptoundecanoic acid (11-MUA) for 30 min under ultraviolet (UV) light, which was accompanied by a PL wavelength shift to the green region (~520 nm). UV-light irradiation accelerates 11-MUA assembly on the 11-MUTABAu NDs (11-MUA/11-MUTAB-Au NDs) through a radical-mediated reaction. Furthermore, the PL wavelength of the 11-MUA/11-MUTAB-Au NDs can be switched to 640 nm via cysteamine under UV-light irradiation. We propose that the PL of the Au NDs with NIR and visible emissions was originally from the surface thiol-Au complexes and the Au core, respectively. These dramatically different optical properties of the Au NDs were due to variation in the surface ligands, as well as the densities and surface oxidant states of the surface Au atoms/ions. These effects can be controlled by assembling surface thiol ligands and accelerated by UV irradiation.In this study, we have developed a simple photoassisted ligand assembly to fine-tune the photoluminescence (PL) of (11-mercaptoundecyl)-N,N,N-trimethylammonium bromide-capped gold nanodots (11-MUTAB-Au NDs). The 11-MUTAB-Au NDs (size: ca. 1.8 nm), obtained from the reaction of gold nanoparticles (ca. 3 nm) and 11-MUTAB, exhibited weak, near-infrared (NIR) PL at 700 nm with a quantum yield (QY) of 0.37% upon excitation at 365 nm. The PL QY of the Au NDs increased to 11.43% after reaction with 11-mercaptoundecanoic acid (11-MUA) for 30 min under ultraviolet (UV) light, which was accompanied by a PL wavelength shift to the green region

  10. Cdc5-Dependent Asymmetric Localization of Bfa1 Fine-Tunes Timely Mitotic Exit

    PubMed Central

    Bahk, Young Yil; Song, Kiwon

    2012-01-01

    In budding yeast, the major regulator of the mitotic exit network (MEN) is Tem1, a GTPase, which is inhibited by the GTPase-activating protein (GAP), Bfa1/Bub2. Asymmetric Bfa1 localization to the bud-directed spindle pole body (SPB) during metaphase also controls mitotic exit, but the molecular mechanism and function of this localization are not well understood, particularly in unperturbed cells. We identified four novel Cdc5 target residues within the Bfa1 C-terminus: 452S, 453S, 454S, and 559S. A Bfa1 mutant in which all of these residues had been changed to alanine (Bfa14A) persisted on both SPBs at anaphase and was hypo-phosphorylated, despite retaining its GAP activity for Tem1. A Bfa1 phospho-mimetic mutant in which all of these residues were switched to aspartate (Bfa14D) always localized asymmetrically to the SPB. These observations demonstrate that asymmetric localization of Bfa1 is tightly linked to its Cdc5-dependent phosphorylation, but not to its GAP activity. Consistent with this, in kinase-defective cdc5-2 cells Bfa1 was not phosphorylated and localized to both SPBs, whereas Bfa14D was asymmetrically localized. BFA14A cells progressed through anaphase normally but displayed delayed mitotic exit in unperturbed cell cycles, while BFA14D cells underwent mitotic exit with the same kinetics as wild-type cells. We suggest that Cdc5 induces the asymmetric distribution of Bfa1 to the bud-directed SPB independently of Bfa1 GAP activity at anaphase and that Bfa1 asymmetry fine-tunes the timing of MEN activation in unperturbed cell cycles. PMID:22253605

  11. Selective loss of fine tuning of Gq/11 signaling by RGS2 protein exacerbates cardiomyocyte hypertrophy.

    PubMed

    Zhang, Wei; Anger, Thomas; Su, Jialin; Hao, Jianming; Xu, Xiaomei; Zhu, Ming; Gach, Agnieszka; Cui, Lei; Liao, Ronglih; Mende, Ulrike

    2006-03-03

    Alterations in cardiac G protein-mediated signaling, most prominently G(q/11) signaling, are centrally involved in hypertrophy and heart failure development. Several RGS proteins that can act as negative regulators of G protein signaling are expressed in the heart, but their functional roles are still poorly understood. RGS expression changes have been described in hypertrophic and failing hearts. In this study, we report a marked decrease in RGS2 (but not other major cardiac RGS proteins (RGS3-RGS5)) that occurs prior to hypertrophy development in different models with enhanced G(q/11) signaling (transgenic expression of activated Galpha(q)(*) and pressure overload due to aortic constriction). To assess functional consequences of selective down-regulation of endogenous RGS2, we identified targeting sequences for effective RGS2 RNA interference and used lipid-based transfection to achieve uptake of fluorescently labeled RGS2 small interfering RNA in >90% of neonatal and adult ventricular myocytes. Endogenous RGS2 expression was dose-dependently suppressed (up to 90%) with no major change in RGS3-RGS5. RGS2 knockdown increased phenylephrine- and endothelin-1-induced phospholipase Cbeta stimulation in both cell types and exacerbated the hypertrophic effect (increase in cell size and radiolabeled protein) in neonatal myocytes, with no major change in G(q/11)-mediated ERK1/2, p38, or JNK activation. Taken together, this study demonstrates that endogenous RGS2 exerts functionally important inhibitory restraint on G(q/11)-mediated phospholipase Cbeta activation and hypertrophy in ventricular myocytes. Our findings point toward a potential pathophysiological role of loss of fine tuning due to selective RGS2 down-regulation in G(q/11)-mediated remodeling. Furthermore, this study shows the feasibility of effective RNA interference in cardiomyocytes using lipid-based small interfering RNA transfection.

  12. A versatile apparatus for the fine-tuned synthesis of cluster-based materials

    SciTech Connect

    Fischer, A. Kruk, R.; Hahn, H.

    2015-02-15

    In this paper, a custom-designed experimental setup for the fine-tuned synthesis of various cluster–based materials is presented. Providing custom-designed deposition stages and special sample holders it offers a high degree of control over the sample characteristics such as the cluster size, cluster amounts, and sample homogeneity in combination with high sample purity. The system is capable of producing thin films of pure clusters and various cluster-matrix combinations with cluster sizes ranging from single atoms up to aggregates of several thousand atoms. Two custom-designed deposition stages are available, one utilizes the full cluster beam, yielding micrograms of pure clusters within a few hours and the second one uses mass-separated clusters (mass-resolution between 2% and 10%), yielding nanograms of pure clusters in the same timescale. Furthermore, at the second deposition stage, a variety of matrix materials can be co-deposited at a controlled sample temperature between 153 K and 673 K. In order to prove the capabilities of the apparatus, a series of experiments with Fe clusters embedded in Ag matrices with different volume fractions of clusters were carried out. Energy dispersive X-ray spectroscopy measurements revealed that the amount of deposited clusters as well as the sample homogeneity can be controlled with an outstanding accuracy of 10%. Additional measurements of the magnetic properties indicated the presence of separated clusters for volume fractions of clusters around 2 volume percent (vol. %), while above this concentration (10 vol. %) a partial aggregation of the clusters was observed. It was also shown that the resulting thin films are nearly oxygen free, which ascertains that oxygen sensitive materials can be safely handled in this newly developed apparatus.

  13. Fine-tuning of NADH oxidase decreases byproduct accumulation in respiration deficient xylose metabolic Saccharomyces cerevisiae

    PubMed Central

    2014-01-01

    Background Efficiently utilizing all available carbon from lignocellulosic feedstock presents a major barrier to the production of economically feasible biofuel. Previously, to enable xylose utilization, we introduced a cofactor-dependent xylose reductase (XR) and xylitol dehydrogenase (XDH) pathway, or a cofactor-independent xylose isomerase (XI) pathway, into Saccharomyces cerevisiae. The resulting strains metabolized xylose with high efficiency. However, in both pathway recombinant strains, the cofactor imbalance caused accumulation of the byproducts glycerol and/or xylitol and reduced the ethanol production efficiency. Results In this study, we introduced NADH oxidase from Lactococcus lactis into both XI and XR-XDH pathway recombinant strains. To reduce byproduct accumulation while maintaining xylose metabolism, we optimized the expression level of NADH oxidase by comparing its expression under the control of different promoters and plasmids. In recombinant XI strains, NADH oxidase was expressed at different levels, regulated by the GPD2 promoter or TEF1 promoter in the 2 μ plasmid. The expression under the control of GPD2 promoter decreased glycerol production by 84% and increased the ethanol yield and specific growth rate by 8% and 12%, respectively. In contrast, in the recombinant XR-XDH strains, such expression level was not efficient enough to decrease the byproduct accumulation. Therefore, higher NADH oxidase expression levels were tested. In the strain expressing NADH oxidase under the control of the TEF1 promoter in the centromeric plasmids, xylitol and glycerol production were reduced by 60% and 83%, respectively, without significantly affecting xylose consumption. Conclusions By fine-tuning NADH oxidase expression, we decreased the glycerol or/and xylitol production in both recombinant XI and XR-XDH xylose-metabolizing yeast strains. The optimal NADH oxidase expression levels depend on metabolic pathways. Similar cofactor engineering strategies

  14. A role for TRIANGULAR HULL1 in fine-tuning spikelet morphogenesis in rice.

    PubMed

    Sato, Dai-Suke; Ohmori, Yoshihiro; Nagashima, Haruka; Toriba, Taiyo; Hirano, Hiro-Yuki

    2014-01-01

    The lemma and palea, which enclose the pistil, stamens, and lodicules, are the most conspicuous organs in the rice spikelet. We isolated a mutant line (ng6569) in which the lemma and palea were narrower than those of the wild type, and found that the mutant had a defect in TRIANGULAR HULL1 (TH1), which encodes a nuclear protein with an ALOG domain. Detailed morphological analysis indicated that the th1 mutation caused a reduction in the size of tubercles, which are convex structures on the surface of the lemma and palea. This reduction was more pronounced in the apical region of the lemma than in the basal region, resulting in the formation of a beak-like spikelet. By contrast, the number of tubercle rows and their spatial distribution on the lemma were not affected in the th1 mutant. Thus, the TH1 gene seems to be involved in fine-tuning the morphogenesis of the lemma and palea. In situ hybridization analysis revealed that TH1 was highly expressed in the primordia of the lemma and palea, but only weakly expressed in the primordia of the sterile lemma and rudimentary glume. We then examined the effect of th1 mutation on the lemma-like structure formed in the long sterile lemma/glume1 (g1) and extra glume1 (eg1) mutants. The result showed that the th1 mutation strongly affected the morphology of the extra lemma of eg1, but had no significant effect on the transformed lemma of g1.

  15. Conformational Fine-Tuning of Pore-Forming Peptide Potency and Selectivity

    PubMed Central

    2015-01-01

    To better understand the sequence–structure–function relationships that control the activity and selectivity of membrane-permeabilizing peptides, we screened a peptide library, based on the archetypal pore-former melittin, for loss-of-function variants. This was accomplished by assaying library members for failure to cause leakage of entrapped contents from synthetic lipid vesicles at a peptide-to-lipid ratio of 1:20, 10-fold higher than the concentration at which melittin efficiently permeabilizes the same vesicles. Surprisingly, about one-third of the library members are inactive under these conditions. In the negative peptides, two changes of hydrophobic residues to glycine were especially abundant. We show that loss-of-function activity can be completely recapitulated by a single-residue change of the leucine at position 16 to glycine. Unlike the potently cytolytic melittin, the loss-of-function peptides, including the single-site variant, are essentially inactive against phosphatidylcholine vesicles and multiple types of eukaryotic cells. Loss of function is shown to result from a shift in the binding–folding equilibrium away from the active, bound, α-helical state toward the inactive, unbound, random-coil state. Accordingly, the addition of anionic lipids to synthetic lipid vesicles restored binding, α-helical secondary structure, and potent activity of the “negative” peptides. While nontoxic to mammalian cells, the single-site variant has potent bactericidal activity, consistent with the anionic nature of bacterial membranes. The results show that conformational fine-tuning of helical pore-forming peptides is a powerful way to modulate their activity and selectivity. PMID:26632653

  16. Quasi-Yukawa unification and fine-tuning in U(1) extended SSM

    NASA Astrophysics Data System (ADS)

    Hiçyılmaz, Yaşar; Ceylan, Meltem; Altaş, Aslı; Solmaz, Levent; Ün, Cem Salih

    2016-11-01

    We consider the low scale implications in the U(1 ) ' extended minimal supersymmetric Standard Model (UMSSM). We restrict the parameter space such that the lightest supersymmetric particle (LSP) is always the lightest neutralino. In addition, we impose quasi-Yukawa unification (QYU) at the grand unification scale (MGUT). QYU strictly requires the ratios among the Yukawa couplings as yt/yb˜1.2 , yτ/yb˜1.4 , and yt/yτ˜0.8 . We find that the need for fine-tuning over the fundamental parameter space of QYU is in the acceptable range (ΔEW≤1 03), even if the universal boundary conditions are imposed at MGUT, in contrast to CMSSM and nonuniversal Higgs masses. The UMSSM with universal boundary conditions yields heavy stops (mt ˜≳2.5 TeV ), gluinos (mg ˜≳2 TeV ), and squarks from the first two families (mq ˜≳4 TeV ). Similarly, the stau mass is bounded from below at about 1.5 TeV. Despite this heavy spectrum, we find ΔEW≳300 , which is much lower than that needed for the minimal supersymmetric models. In addition, the UMSSM yields a relatively small μ term, and the LSP neutralino is mostly formed by the Higgsinos of mass ≳700 GeV . We also obtain bino-like dark matter of mass about 400 GeV. The wino is usually found to be heavier than Higgsinos and binos, but there is a small region where μ ˜M1˜M2˜1 TeV . We also identify a chargino-neutralino coannihilation channel and A -resonance solutions which reduce the relic abundance of LSP neutralinos down to the ranges compatible with the current WMAP and Planck measurements.

  17. Finely tuned regulation of the aromatic amine degradation pathway in Escherichia coli.

    PubMed

    Zeng, Ji; Spiro, Stephen

    2013-11-01

    FeaR is an AraC family regulator that activates transcription of the tynA and feaB genes in Escherichia coli. TynA is a periplasmic topaquinone- and copper-containing amine oxidase, and FeaB is a cytosolic NAD-linked aldehyde dehydrogenase. Phenylethylamine, tyramine, and dopamine are oxidized by TynA to the corresponding aldehydes, releasing one equivalent of H2O2 and NH3. The aldehydes can be oxidized to carboxylic acids by FeaB, and (in the case of phenylacetate) can be further degraded to enter central metabolism. Thus, phenylethylamine can be used as a carbon and nitrogen source, while tyramine and dopamine can be used only as sources of nitrogen. Using genetic, biochemical and computational approaches, we show that the FeaR binding site is a TGNCA-N8-AAA motif that occurs in 2 copies in the tynA and feaB promoters. We show that the coactivator for FeaR is the product rather than the substrate of the TynA reaction. The feaR gene is upregulated by carbon or nitrogen limitation, which we propose reflects regulation of feaR by the cyclic AMP receptor protein (CRP) and the nitrogen assimilation control protein (NAC), respectively. In carbon-limited cells grown in the presence of a TynA substrate, tynA and feaB are induced, whereas in nitrogen-limited cells, only the tynA promoter is induced. We propose that tynA and feaB expression is finely tuned to provide the FeaB activity that is required for carbon source utilization and the TynA activity required for nitrogen and carbon source utilization.

  18. Cell-Specific Fine-Tuning of Neuronal Excitability by Differential Expression of Modulator Protein Isoforms

    PubMed Central

    Jepson, James; Sheldon, Amanda; Shahidullah, Mohammad; Fei, Hong; Koh, Kyunghee

    2013-01-01

    SLOB (SLOWPOKE-binding protein) modulates the Drosophila SLOWPOKE calcium-activated potassium channel. We have shown previously that SLOB deletion or RNAi knockdown decreases excitability of neurosecretory pars intercerebralis (PI) neurons in the adult Drosophila brain. In contrast, we found that SLOB deletion/knockdown enhances neurotransmitter release from motor neurons at the fly larval neuromuscular junction, suggesting an increase in excitability. Because two prominent SLOB isoforms, SLOB57 and SLOB71, modulate SLOWPOKE channels in opposite directions in vitro, we investigated whether divergent expression patterns of these two isoforms might underlie the differential modulation of excitability in PI and motor neurons. By performing detailed in vitro and in vivo analysis, we found strikingly different modes of regulatory control by the slob57 and slob71 promoters. The slob71, but not slob57, promoter contains binding sites for the Hunchback and Mirror transcriptional repressors. Furthermore, several core promoter elements that are absent in the slob57 promoter coordinately drive robust expression of a luciferase vector by the slob71 promoter in vitro. In addition, we visualized the expression patterns of the slob57 and slob71 promoters in vivo and found clear spatiotemporal differences in promoter activity. SLOB57 is expressed prominently in adult PI neurons, whereas larval motor neurons exclusively express SLOB71. In contrast, at the larval neuromuscular junction, SLOB57 expression appears to be restricted mainly to a subset of glial cells. Our results illustrate how the use of alternative transcriptional start sites within an ion channel modulator locus coupled with functionally relevant alternative splicing can be used to fine-tune neuronal excitability in a cell-specific manner. PMID:24133277

  19. The S1 helix critically regulates the finely tuned gating of Kv11.1 channels

    PubMed Central

    Phan, Kevin; Ng, Chai Ann; David, Erikka; Shishmarev, Dmitry; Kuchel, Philip W.; Vandenberg, Jamie I.; Perry, Matthew D.

    2017-01-01

    Congenital mutations in the cardiac Kv11.1 channel can cause long QT syndrome type 2 (LQTS2), a heart rhythm disorder associated with sudden cardiac death. Mutations act either by reducing protein expression at the membrane and/or by perturbing the intricate gating properties of Kv11.1 channels. A number of clinical LQTS2-associated mutations have been reported in the first transmembrane segment (S1) of Kv11.1 channels, but the role of this region of the channel is largely unexplored. In part, this is due to problems defining the extent of the S1 helix, as a consequence of its low sequence homology with other Kv family members. Here, we used NMR spectroscopy and electrophysiological characterization to show that the S1 of Kv11.1 channels extends seven helical turns, from Pro-405 to Phe-431, and is flanked by unstructured loops. Functional analysis suggests that pre-S1 loop residues His-402 and Tyr-403 play an important role in regulating the kinetics and voltage dependence of channel activation and deactivation. Multiple residues within the S1 helix also play an important role in fine-tuning the voltage dependence of activation, regulating slow deactivation, and modulating C-type inactivation of Kv11.1 channels. Analyses of LQTS2-associated mutations in the pre-S1 loop or S1 helix of Kv11.1 channels demonstrate perturbations to both protein expression and most gating transitions. Thus, S1 region mutations would reduce both the action potential repolarizing current passed by Kv11.1 channels in cardiac myocytes, as well as the current passed in response to premature depolarizations that normally helps protect against the formation of ectopic beats. PMID:28280240

  20. Lysine succinylation of Mycobacterium tuberculosis isocitrate lyase (ICL) fine-tunes the microbial resistance to antibiotics.

    PubMed

    Zhou, Mingliang; Xie, Longxiang; Yang, Zhaozhen; Zhou, Jiahai; Xie, Jianping

    2017-04-01

    Lysine succinylation (Ksucc) is a newly identified protein posttranslational modification (PTM), which may play an important role in cellular physiology. However, the role of lysine succinylation in antibiotic resistance remains elusive. Isocitrate lyase (ICL) is crucial for broad-spectrum antibiotics tolerance in Mycobacterium tuberculosis (Mtb). We previously found that MtbICL (Rv0467) has at least three succinylated lysine residues, namely K189, K322, and K334.To explore the effect of succinylation on the activity of MtbICL, mutants' mimicry of the lysine succinylation were generated by site-directed mutagenesis. ICL-K189E mutant strain is more sensitive than the wild-type to rifampicin and streptomycin, but not isoniazid. For the in vitro activity of the purified isocitrate lyase, only K189E mutant showed significantly decreased activity. Crystal structure analysis showed that Lys189 Glu dramatically increased the pKa of Glu188 and decreased the pKa of Lys190, whereas had negligible effect on other residues within 5 Å as well as disruption of the electrostatic interaction between Lys189 and Glu182, which might prevent the closure of the active site loop and cause severe reduction of the enzyme activity. Considering the genetic, biochemical, and crystallographical evidences together, the succinylation of specific ICL residue can fine-tune the bacterial resistance to selected antibiotics. The decreased enzymatic activity resulting from the succinylation-changed electrostatic interaction might underlie this phenotype. This study provided the first insight into the link between lysine succinylation and antibiotic resistance.

  1. The Formation of Uranus and Neptune: Fine-tuning in Core Accretion

    NASA Astrophysics Data System (ADS)

    Frelikh, Renata; Murray-Clay, Ruth A.

    2017-09-01

    Uranus and Neptune are ice giants with ∼15% atmospheres by mass, which places them in a category intermediate between rocky planets and gas giants. These atmospheres are too massive to have been primarily outgassed, but they never underwent runaway gas accretion. The ice giants never reached critical core mass ({M}{crit}) in a full gas disk, but their cores are ≳ {M}{crit}, suggesting that their envelopes were mainly accreted at the end of the disk lifetime. Pebble accretion calls into question traditional slow atmospheric growth during this phase. We show that the full-sized ice giants predominantly accreted gas from a disk depleted by at least a factor of ∼100. Such a disk dissipates in ≲105 years. Why would both cores stay subcritical for the entire ∼Myr disk lifetime, only to reach {M}{crit} in the final 105 years? This is fine tuned. Ice giants in the outer disk have atmospheric mass fractions comparable to the disk gas-to-solid ratio during the bulk of their gas accretion. This point in disk evolution coincides with a dynamical upheaval: the gas loses its ability to efficiently damp the core random velocities, allowing them to be gravitationally excited by Jupiter and Saturn. We suggest that the ice giants’ cores began growing on closer-in orbits (staying subcritical), and migrated out during this dynamical instability. There, their orbits circularized after accreting much of their mass in solids. Finally, they accreted their envelopes from a depleted nebula, where the sparseness of feeding-zone gas prevented runaway.

  2. Fine-tuned evaluation of olfactory function in patients operated for nasal polyposis.

    PubMed

    Sonnet, Marie-Hortense; Nguyen, Duc Trung; Nguyen-Thi, Phi-Linh; Arous, Fabien; Jankowski, Roger; Rumeau, Cécile

    2017-07-01

    Given the forced-choice procedure of the identification test, patients with profound anosmia are more likely to have higher identification scores by chance than patients with hyposmia or normosmia. This may be a confusing factor when assessing the sense of smell, which alters the appreciation of real olfaction improvement. The aim of this study was to fine-tune the results of the identification Sniffin' Sticks test before and 6 weeks after surgery using the real identification score. A total of 133 patients underwent the Identification (I) and Threshold (T) tests the day before and 6 weeks after nasalization surgery. The scores of the identification test, called I G (global identification), were ranked from 0 to 16. Patients had to specify if their forced-choice answers were given either surely or randomly, called I H (hazard identification). The real score of identification I R was obtained as follow: I R = I G - I H. Patients with an immeasurable threshold according to the T test were more prone to give randomly correct answers. On the basis of I G scores, 43.6% of patients remained hypo-anosmic after surgery compared to 72.9% before surgery. Using I R scores, only 3.8% of patients remained anosmic (I R = 0) at 6 weeks after surgery. Hence, patients with real anosmia (I R = 0) were less prone to improve their olfaction than patients with I R > 0. The analysis of random factor when using identification test allows differentiating a real anosmia from a hyposmia. An I G ≤ 4 could be considered as a profound/real anosmia or a severe hyposmia. This procedure cannot, however, replace the forced-choice method in odor identification testing.

  3. New approach to assess sperm DNA fragmentation dynamics: Fine-tuning mathematical models.

    PubMed

    Ortiz, Isabel; Dorado, Jesús; Morrell, Jane; Gosálvez, Jaime; Crespo, Francisco; Jiménez, Juan M; Hidalgo, Manuel

    2017-01-01

    Sperm DNA fragmentation (sDF) has been proved to be an important parameter in order to predict in vitro the potential fertility of a semen sample. Colloid centrifugation could be a suitable technique to select those donkey sperm more resistant to DNA fragmentation after thawing. Previous studies have shown that to elucidate the latent damage of the DNA molecule, sDF should be assessed dynamically, where the rate of fragmentation between treatments indicates how resistant the DNA is to iatrogenic damage. The rate of fragmentation is calculated using the slope of a linear regression equation. However, it has not been studied if sDF dynamics fit this model. The objectives of this study were to evaluate the effect of different after-thawing centrifugation protocols on sperm DNA fragmentation and elucidate the most accurate mathematical model (linear regression, exponential or polynomial) for DNA fragmentation over time in frozen-thawed donkey semen. After submitting post-thaw semen samples to no centrifugation (UDC), sperm washing (SW) or single layer centrifugation (SLC) protocols, sDF values after 6 h of incubation were significantly lower in SLC samples than in SW or UDC. Coefficient of determination (R(2)) values were significantly higher for a second order polynomial model than for linear or exponential. The highest values for acceleration of fragmentation (aSDF) were obtained for SW, followed by SLC and UDC. SLC after thawing seems to preserve longer DNA longevity in comparison to UDC and SW. Moreover, the fine-tuning of models has shown that sDF dynamics in frozen-thawed donkey semen fit a second order polynomial model, which implies that fragmentation rate is not constant and fragmentation acceleration must be taken into account to elucidate hidden damage in the DNA molecule.

  4. Causes and consequences of repeatability, flexibility and individual fine-tuning of migratory timing in pike.

    PubMed

    Tibblin, Petter; Forsman, Anders; Borger, Tobias; Larsson, Per

    2016-01-01

    Many organisms undertake migrations between foraging and breeding habitats and while it is assumed that reproductive timing affects fitness, little is known about the degree of individual consistency, and about the causes and consequences of individual variation in migratory timing in organisms other than birds. Here, we report on a 6-year mark-recapture study, including 2048 individuals, of breeding migration in anadromous pike (Esox lucius), an iteroparous top-predatory fish that displays homing behaviour. By repeated sampling across years at a breeding site, we first quantify individual variation both within and between breeding events and then investigate phenotypic correlates and fitness consequences of arrival timing to the breeding site. Our data demonstrate that males arrive before females, that large males arrive later than small males, that the timing of breeding migration varies among years and that individuals are consistent in their timing across years relative to other individuals in the population. Furthermore, data on return rates indicate that arrival time is under stabilizing viability selection, and that individuals who are more flexible in their timing of arrival during the first reproductive years survive longer compared with less flexible individuals. Finally, longitudinal data demonstrate that individuals consistently fine-tune their arrival timing across years, showing that the timing of arrival to breeding sites is influenced by experience. These findings represent rare evidence of how between- and within-individual variations in migratory timing across breeding events are correlated with phenotypic and fitness traits in an ecologically important keystone species. Our results emphasize the importance of considering variation in migratory timing both between and within individuals in studies investigating the fitness consequences of migratory behaviour and have implications for future management. © 2015 The Authors. Journal of Animal

  5. Leaf color is fine-tuned on the solar spectra to avoid strand direct solar radiation.

    PubMed

    Kume, Atsushi; Akitsu, Tomoko; Nasahara, Kenlo Nishida

    2016-07-01

    The spectral distributions of light absorption rates by intact leaves are notably different from the incident solar radiation spectra, for reasons that remain elusive. Incident global radiation comprises two main components; direct radiation from the direction of the sun, and diffuse radiation, which is sunlight scattered by molecules, aerosols and clouds. Both irradiance and photon flux density spectra differ between direct and diffuse radiation in their magnitude and profile. However, most research has assumed that the spectra of photosynthetically active radiation (PAR) can be averaged, without considering the radiation classes. We used paired spectroradiometers to sample direct and diffuse solar radiation, and obtained relationships between the PAR spectra and the absorption spectra of photosynthetic pigments and organs. As monomers in solvent, the spectral absorbance of Chl a decreased with the increased spectral irradiance (W m(-2) nm(-1)) of global PAR at noon (R(2) = 0.76), and was suitable to avoid strong spectral irradiance (λmax = 480 nm) rather than absorb photon flux density (μmol m(-2) s(-1) nm(-1)) efficiently. The spectral absorption of photosystems and the intact thallus and leaves decreased linearly with the increased spectral irradiance of direct PAR at noon (I dir-max), where the wavelength was within the 450-650 nm range (R(2) = 0.81). The higher-order structure of photosystems systematically avoided the strong spectral irradiance of I dir-max. However, when whole leaves were considered, leaf anatomical structure and light scattering in leaf tissues made the leaves grey bodies for PAR and enabled high PAR use efficiency. Terrestrial green plants are fine-tuned to spectral dynamics of incident solar radiation and PAR absorption is increased in various structural hierarchies.

  6. Body appendages fine-tune posture and moments in freely manoeuvring fruit flies.

    PubMed

    Berthé, Ruben; Lehmann, Fritz-Olaf

    2015-10-01

    The precise control of body posture by turning moments is key to elevated locomotor performance in flying animals. Although elevated moments for body stabilization are typically produced by wing aerodynamics, animals also steer using drag on body appendages, shifting their centre of body mass, and changing moments of inertia caused by active alterations in body shape. To estimate the instantaneous contribution of each of these components for posture control in an insect, we three-dimensionally reconstructed body posture and movements of body appendages in freely manoeuvring fruit flies (Drosophila melanogaster) by high-speed video and experimentally scored drag coefficients of legs and body trunk at low Reynolds number. The results show that the sum of leg- and abdomen-induced yaw moments dominates wing-induced moments during 17% of total flight time but is, on average, 7.2-times (roll, 3.4-times) smaller during manoeuvring. Our data reject a previous hypothesis on synergistic moment support, indicating that drag on body appendages and mass-shift inhibit rather than support turning moments produced by the wings. Numerical modelling further shows that hind leg extension alters the moments of inertia around the three main body axes of the animal by not more than 6% during manoeuvring, which is significantly less than previously reported for other insects. In sum, yaw, pitch and roll steering by body appendages probably fine-tune turning behaviour and body posture, without providing a significant advantage for posture stability and moment support. Motion control of appendages might thus be part of the insect's trimming reflexes, which reduce imbalances in moment generation caused by unilateral wing damage and abnormal asymmetries of the flight apparatus. © 2015. Published by The Company of Biologists Ltd.

  7. Experimental methods of post-growth-tuning of the excitonic fine structure splitting in semiconductor quantum dots.

    PubMed

    Plumhof, Johannes D; Trotta, Rinaldo; Rastelli, Armando; Schmidt, Oliver G

    2012-01-01

    Deterministic sources of polarization entangled photon pairs on demand are considered as important building block for quantum communication technology. It has been demonstrated that semiconductor quantum dots (QDs), exhibiting a sufficiently small excitonic fine structure splitting (FSS) can be used as triggered, on-chip sources of polarization entangled photon pairs. As-grown QDs usually do not exhibit the required values of the FSS, making the availability of post-growth tuning techniques highly desired. This article reviews the effect of different post-growth treatments and external fields on the FSS such as thermal annealing, magnetic fields, the optical Stark effect, electric fields and anisotropic stress. As a consequence of the tuning of the FSS for some tuning techniques a rotation of the polarization of the emitted light is observed. The joint modification of polarization orientation and FSS can be described by an anticrossing of the bright excitonic states.

  8. Survey of plasmonic gaps tuned at sub-nanometer scale in self-assembled arrays

    NASA Astrophysics Data System (ADS)

    Qian, Li-Hua; Yi, Li-Zhi; Wang, Gui-Sheng; Zhang, Chao; Yuan, Song-Liu

    2016-04-01

    Creating nanoscale and sub-nanometer gaps between noble metal nanoparticles is critical for the applications of plasmonics and nanophotonics. To realize simultaneous attainments of both the optical spectrum and the gap size, the ability to tune these nanoscale gaps at the sub-nanometer scale is particularly desirable. Many nanofabrication methodologies, including electron beam lithography, self-assembly, and focused ion beams, have been tested for creating nanoscale gaps that can deliver significant field enhancement. Here, we survey recent progress in both the reliable creation of nanoscale gaps in nanoparticle arrays using self-assemblies and in the in-situ tuning techniques at the sub-nanometer scale. Precisely tunable gaps, as we expect, will be good candidates for future investigations of surface-enhanced Raman scattering, non-linear optics, and quantum plasmonics.

  9. Coupling and tuning of modal frequencies in direct current biased microelectromechanical systems arrays

    SciTech Connect

    Kambali, Prashant N.; Swain, Gyanadutta; Pandey, Ashok Kumar; Buks, Eyal; Gottlieb, Oded

    2015-08-10

    Understanding the coupling of different modal frequencies and their tuning mechanisms has become essential to design multi-frequency MEMS devices. In this work, we fabricate a MEMS beam with fixed boundaries separated from two side electrodes and a bottom electrode. Subsequently, we perform experiments to obtain the frequency variation of in-plane and out-of-plane mechanical modes of the microbeam with respect to both DC bias and laser heating. We show that the frequencies of the two modes coincide at a certain DC bias, which in turn can also be varied due to temperature. Subsequently, we develop a theoretical model to predict the variation of the two modes and their coupling due to a variable gap between the microbeam and electrodes, initial tension, and fringing field coefficients. Finally, we discuss the influence of frequency tuning parameters in arrays of 3, 33, and 40 microbeams, respectively. It is also found that the frequency bandwidth of a microbeam array can be increased to as high as 25 kHz for a 40 microbeam array with a DC bias of 80 V.

  10. Coarse and fine N1 tuning for print in younger and older Chinese children: Orthography, phonology, or semantics driven?

    PubMed

    Tong, Xiuhong; Lo, Jason Chor Ming; McBride, Catherine; Ho, Connie Suk-Han; Waye, Mary Miu Yee; Chung, Kevin Kien Hoa; Wong, Simpson Wai Lap; Chow, Bonnie Wing-Yin

    2016-10-01

    Visual expertise in distinguishing words from objects and word-like stimuli is a fundamental skill that is important for children to become proficient readers. This expertise can be indexed by the N1 component of ERPs at the neural level. However, the nature of N1 tuning for print is controversial in terms of onset of the latency, lateralization and the neural mechanism of the N1. This study aimed to investigate whether two groups of Chinese children could discriminate characters/character-like stimuli from visual controls (i.e., coarse N1 tuning) and distinguish characters from character-like stimuli (i.e., fine N1 tuning). We also explored the cognitive-linguistic correlates of N1 tuning. Seventeen children in the younger group (M=7.7 years) and 13 in the older group (M=9.4 years) were all required to finish a character decision task with character, pseudocharacter, noncharacter, and stroke combination conditions using ERP testing. Both the pseudocharacters and noncharacters were unpronounceable, and the main difference between the two conditions was in orthographic presentation (i.e., radical position). Children were also administered measures of reading fluency, reading accuracy, RAN, phonological skill and vocabulary knowledge. ERP results showed that a significantly larger N1 was observed in the characters, pseudocharacters, and noncharacters as compared to the stroke combinations in both groups. The N1 for characters and pseudocharacters was also significantly larger than that for noncharacters in both groups. Both coarse and fine N1s were larger for younger children than for older children, and the N1 was bilateral in younger children, but left lateralized in older children. Correlational analyses showed that the coarse N1 tuning of real characters versus visual controls was moderately correlated with reading fluency and accuracy but not RAN, phonology, or vocabulary. Taken together, our study suggests that both coarse and fine N1 tuning occurs in both

  11. Decoding techniques for fine-fine geometry multi-anode microchannel arrays

    NASA Technical Reports Server (NTRS)

    Kasle, David B.

    1988-01-01

    The Multi-Anode Microchannel Array (MAMA) is a photon-counting detector which decodes the position of an event through coincidence discrimination. The decoding algorithm which associates a given event with the appropriate pixel is determined by the geometry of the array. The decoding process can be divided into two tasks: anode encoding and pixel decoding. Techniques for performing both tasks are described and contrasted in light of application requirements. Decode times of 75 nanoseconds have been achieved, and considerably faster decoders are possible given new architectures and technologies.

  12. Decoding techniques for fine-fine geometry multi-anode microchannel arrays

    NASA Technical Reports Server (NTRS)

    Kasle, David B.

    1988-01-01

    The Multi-Anode Microchannel Array (MAMA) is a photon-counting detector which decodes the position of an event through coincidence discrimination. The decoding algorithm which associates a given event with the appropriate pixel is determined by the geometry of the array. The decoding process can be divided into two tasks: anode encoding and pixel decoding. Techniques for performing both tasks are described and contrasted in light of application requirements. Decode times of 75 nanoseconds have been achieved, and considerably faster decoders are possible given new architectures and technologies.

  13. Nanostructured Arrays Formed by Finely Focused Ion Beams

    SciTech Connect

    Budai, J.D.; Datsos, P.G.; Feldman, L.C.; Heinig, K.-H.; Meldrum, A.; Strobel, M.; Thomas, K.A.; Warmack, R.J.; White, C.W.; Zuhr, R.A.

    1998-11-30

    Amorphous, polycrystalline, and single crystal nanometer dimension particles can be formed in a variety of substrates by ion implantation and subsequent annealing. Such composite colloidal materials exhibit unique optical properties that could be useful in optical devices, switches, and waveguides. However colloids formed by blanket implantation are not uniform in size due to the nonuniform density of the implant, resulting in diminution of the size dependent optical properties. The object of the present work is to form more uniform size particles arranged in a 2-dimensional lattice by using a finely focused ion beam to implant identical ion doses only into nanometer size regions located at each point of a rectangular lattice. Initial work is being done with a 30 keV Ga beam implanted into Si. Results of particle formation as a function of implant conditions as analyzed by Rutherford backscattering, x-ray analysis, atomic force microscopy, and both scanning and transmission electron microscopy will be presented and discussed.

  14. Fine-Tuning of Mast Cell Activation by FcεRIβ Chain

    PubMed Central

    Ra, Chisei; Nunomura, Satoshi; Okayama, Yoshimichi

    2012-01-01

    Mast cells play a key role in allergic reaction and disorders through the high affinity receptor for IgE (FcεRI) which is primarily activated by IgE and antigen complex. In humans, mast cells express two types of FcεRI on the cell surface, tetrameric αβγ2 and trimeric αγ2, whereas in mice, the tetrameric αβγ2 type is exclusively expressed. In human allergic inflammation lesions, mast cells increase in number and preferentially express the αβγ2 type FcεRI. By contrast, in the lesion of non-allergic inflammation, mast cells mainly express the αγ2type. Since the β chain amplifies the expression and signaling of FcεRI, mast cell effector functions and allergic reaction in vivo are enhanced in the presence of the β chain. In contrast, a truncated β chain-isoform (βT) inhibits FcεRI surface expression. The human FcεRIβ gene contains seven exons and a repressor element located in the forth intron, through which FcεRIβ transcription is repressed in the presence of GM-CSF. Regarding the additional signal regulatory function of the β chain, the β chain ITAM has dual (positive and negative) functions in the regulation of the mast cell activation. Namely, the FcεRIβ chain ITAM enhances the mast cell activation signal triggered by a low-intensity (weak) stimulation whereas it suppresses the signal triggered by high-intensity (strong) stimulation. In an oxazolone-induced mouse CHS model, IgE-mediated mast cell activation is required and the β chain ITAM is crucially involved. Adenosine receptor, one of the GPCRs, triggers a synergistic degranulation response with FcεRI in mast cells, for which the β chain ITAM critically plays positive role, possibly reflecting the in vivo allergic response. These regulatory functions of the FcεRIβ ITAM finely tune FcεRI-induced mast cell activation depending on the stimulation strength, enabling the FcεRIβ chain to become a potential molecular target for the development of new strategies for therapeutic

  15. Self-replicating RNA vaccine functionality modulated by fine-tuning of polyplex delivery vehicle structure.

    PubMed

    Démoulins, Thomas; Ebensen, Thomas; Schulze, Kai; Englezou, Pavlos C; Milona, Panagiota; Pelliccia, Maria; Guzmán, Carlos A; Ruggli, Nicolas; McCullough, Kenneth C

    2017-09-18

    The major limitations with large and complex self-amplifying RNA vaccines (RepRNA) are RNase-sensitivity and inefficient translation in dendritic cells (DCs). Condensing RepRNA with polyethylenimine (PEI) gave positive in vitro readouts, but was largely inferior to virus-like replicon particles (VRP) or direct electroporation. In the present study, we improved such polyplex formulation and determined that fine-tuning of the polyplex structure is essential for ensuring efficacious translation. Thereby, three parameters dominate: (i) PEI molecular weight (MW); (ii) RepRNA:PEI (weight:weight) ratio; and (iii) inclusion of cell penetrating peptides (CPPs). Seven commercially available linear PEIs (MW 2500-250,000) were classified as strong, intermediate or low for their aptitude at complexing and protecting RepRNA for delivery into porcine blood DCs. Inclusion of (Arg)9 or TAT(57-57) CPPs further modified the translation readouts, but varied for different gene expressions. Dependent on the formulation, translation of the gene of interest (GOI) inserted into the RepRNA (luciferase, or influenza virus hemagglutinin or nucleoprotein) could decrease, while the RepRNA structural gene (E2) translation increased. This was noted in the porcine SK6 cell line, as well as both porcine and, for the first time, human DCs. Two formulations - [Rep/PEI-4000 (1:3)] and [Rep/PEI-40,000 (1:2)/(Arg)9] were efficacious in vivo in mice and pigs, where specific CD8(+) T and CD4(+) T-cell responses against the GOI-encoded antigen were observed for the first time. The results demonstrate that different polyplex formulations differ in their interaction with the RepRNA such that only certain genes can be translated. Thus, delivery of these large self-replicating RNA molecules require definition with respect to translation of different genes, rather than just the GOI as is the norm, for identifying optimal delivery for the desired immune activation in vivo. Copyright © 2017. Published by

  16. Local temperature fine-tunes the timing of spring migration in birds.

    PubMed

    Tøttrup, Anders P; Rainio, Kalle; Coppack, Timothy; Lehikoinen, Esa; Rahbek, Carsten; Thorup, Kasper

    2010-09-01

    Evidence for climate-driven phenological changes is rapidly increasing at all trophic levels. Our current poor knowledge of the detailed control of bird migration from the level of genes and hormonal control to direct physiological and behavioral responses hampers our ability to understand and predict consequences of climatic change for migratory birds. In order to better understand migration phenology and adaptation in environmental changes, we here assess the scale at which weather affects timing of spring migration in passerine birds. We use three commonly used proxies of spring-time climatic conditions: (1) vegetation "greenness" (NDVI) in Europe, (2) local spring temperatures in northern Europe, and (3) the North Atlantic Oscillation Index (NAO) as predictors of the phenology of avian migration as well as the strength of their effect on different subsets of populations and the dependence of correlations on species-specific migratory strategy. We analyze phenological patterns of the entire spring migration period in 12 Palaearctic passerine species, drawing on long-term data collected at three locations along a longitudinal gradient situated close to their northern European breeding area. Local temperature was the best single predictor of phenology with the highest explanatory power achieved in combination with NAO. Furthermore, early individuals are more affected by climatic variation compared to individuals on later passage, indicating that climatic change affects subsets of migratory populations differentially. Species wintering closer to the breeding areas were affected more than were those travelling longer distances and this pattern was strongest for the earliest subsets of the population. Overall, our results suggest that at least early subsets of the population are affected by local conditions and early birds use local conditions to fine-tune the date of their spring arrival while individuals arriving later are driven by other factors than local

  17. Polarization-tuned Dynamic Color Filters Incorporating a Dielectric-loaded Aluminum Nanowire Array

    PubMed Central

    Raj Shrestha, Vivek; Lee, Sang-Shin; Kim, Eun-Soo; Choi, Duk-Yong

    2015-01-01

    Nanostructured spectral filters enabling dynamic color-tuning are saliently attractive for implementing ultra-compact color displays and imaging devices. Realization of polarization-induced dynamic color-tuning via one-dimensional periodic nanostructures is highly challenging due to the absence of plasmonic resonances for transverse-electric polarization. Here we demonstrate highly efficient dynamic subtractive color filters incorporating a dielectric-loaded aluminum nanowire array, providing a continuum of customized color according to the incident polarization. Dynamic color filtering was realized relying on selective suppression in transmission spectra via plasmonic resonance at a metal-dielectric interface and guided-mode resonance for a metal-clad dielectric waveguide, each occurring at their characteristic wavelengths for transverse-magnetic and electric polarizations, respectively. A broad palette of colors, including cyan, magenta, and yellow, has been attained with high transmission beyond 80%, by tailoring the period of the nanowire array and the incident polarization. Thanks to low cost, high durability, and mass producibility of the aluminum adopted for the proposed devices, they are anticipated to be diversely applied to color displays, holographic imaging, information encoding, and anti-counterfeiting. PMID:26211625

  18. Fine-Tuning the Antimicrobial Profile of Biocompatible Gold Nanoparticles by Sequential Surface Functionalization Using Polyoxometalates and Lysine

    PubMed Central

    Daima, Hemant K.; Selvakannan, P. R.; Shukla, Ravi; Bhargava, Suresh K.; Bansal, Vipul

    2013-01-01

    Antimicrobial action of nanomaterials is typically assigned to the nanomaterial composition, size and/or shape, whereas influence of complex corona stabilizing the nanoparticle surface is often neglected. We demonstrate sequential surface functionalization of tyrosine-reduced gold nanoparticles (AuNPsTyr) with polyoxometalates (POMs) and lysine to explore controlled chemical functionality-driven antimicrobial activity. Our investigations reveal that highly biocompatible gold nanoparticles can be tuned to be a strong antibacterial agent by fine-tuning their surface properties in a controllable manner. The observation from the antimicrobial studies on a gram negative bacterium Escherichia coli were further validated by investigating the anticancer properties of these step-wise surface-controlled materials against A549 human lung carcinoma cells, which showed a similar toxicity pattern. These studies highlight that the nanomaterial toxicity and biological applicability are strongly governed by their surface corona. PMID:24147146

  19. Tuning exciton energy and fine-structure splitting in single InAs quantum dots by applying uniaxial stress

    SciTech Connect

    Su, Dan; Dou, Xiuming; Wu, Xuefei; Liao, Yongping; Zhou, Pengyu; Ding, Kun; Ni, Haiqiao; Niu, Zhichuan; Zhu, Haijun; Jiang, Desheng; Sun, Baoquan

    2016-04-15

    Exciton and biexciton emission energies as well as excitonic fine-structure splitting (FSS) in single InAs/GaAs quantum dots (QDs) have been continuously tuned in situ in an optical cryostat using a developed uniaxial stress device. With increasing tensile stress, the red shift of excitonic emission is up to 5 nm; FSS decreases firstly and then increases monotonically, reaching a minimum value of approximately 10 μeV; biexciton binding energy decreases from 460 to 106 μeV. This technique provides a simple and convenient means to tune QD structural symmetry, exciton energy and biexciton binding energy and can be used for generating entangled and indistinguishable photons.

  20. Multiple excitatory and inhibitory neural signals converge to fine-tune Caenorhabditis elegans feeding to food availability

    PubMed Central

    Dallière, Nicolas; Bhatla, Nikhil; Luedtke, Zara; Ma, Dengke K.; Woolman, Jonathan; Walker, Robert J.; Holden-Dye, Lindy; O’Connor, Vincent

    2016-01-01

    How an animal matches feeding to food availability is a key question for energy homeostasis. We addressed this in the nematode Caenorhabditis elegans, which couples feeding to the presence of its food (bacteria) by regulating pharyngeal activity (pumping). We scored pumping in the presence of food and over an extended time course of food deprivation in wild-type and mutant worms to determine the neural substrates of adaptive behavior. Removal of food initially suppressed pumping but after 2 h this was accompanied by intermittent periods of high activity. We show pumping is fine-tuned by context-specific neural mechanisms and highlight a key role for inhibitory glutamatergic and excitatory cholinergic/peptidergic drives in the absence of food. Additionally, the synaptic protein UNC-31 [calcium-activated protein for secretion (CAPS)] acts through an inhibitory pathway not explained by previously identified contributions of UNC-31/CAPS to neuropeptide or glutamate transmission. Pumping was unaffected by laser ablation of connectivity between the pharyngeal and central nervous system indicating signals are either humoral or intrinsic to the enteric system. This framework in which control is mediated through finely tuned excitatory and inhibitory drives resonates with mammalian hypothalamic control of feeding and suggests that fundamental regulation of this basic animal behavior may be conserved through evolution from nematode to human.—Dallière, N., Bhatla, N., Luedtke, Z., Ma, D. K., Woolman, J., Walker, R. J., Holden-Dye, L., O’Connor, V. Multiple excitatory and inhibitory neural signals converge to fine-tune Caenorhabditis elegans feeding to food availability. PMID:26514165

  1. Investigation of double-mode operation and fast fine tuning properties of a grating-coupled external cavity diode laser configuration

    NASA Astrophysics Data System (ADS)

    Bayrakli, Ismail

    2017-01-01

    Double-mode operation and fast piezo fine tuning properties of a gain chip on a thermoelectric cooler in an external cavity are investigated. A widely course double-mode tuning range of 120 nm for the spectral range between 1470 and 1590 nm is achieved by rotating the diffraction gratings forming a double Littrow-type configuration. A fast piezo fine tuning range over 7cm-1 (1.5 nm, 210 GHz) in a single-mode operation is obtained by scanning the external cavity length with scan rates up to 0.5 kHz.

  2. Discrete tuning concept for fiber-integrated lasers based on tailored FBG arrays and a theta cavity layout.

    PubMed

    Tiess, Tobias; Becker, Martin; Rothhardt, Manfred; Bartelt, Hartmut; Jäger, Matthias

    2017-03-15

    We demonstrate a novel tuning concept for pulsed fiber-integrated lasers with a fiber Bragg grating (FBG) array as a discrete and tailored spectral filter, as well as a modified laser design. Based on a theta cavity layout, the structural delay lines originating from the FBG array are balanced, enabling a constant repetition rate and stable pulse properties over the full tuning range. The emission wavelength is electrically tuned with respect to the filter properties based on an adapted temporal gating scheme using an acousto-optic modulator. This concept has been investigated with an Yb-doped fiber laser, demonstrating excellent emission properties with high signal contrast (>35  dB) and narrow linewidth (<150  pm) over a tuning range of 25 nm.

  3. Fine Tuning of Chlorophyll Spectra by Protein-Induced Ring Deformation.

    PubMed

    Bednarczyk, Dominika; Dym, Orly; Prabahar, Vadivel; Peleg, Yoav; Pike, Douglas H; Noy, Dror

    2016-06-06

    The ability to tune the light-absorption properties of chlorophylls by their protein environment is the key to the robustness and high efficiency of photosynthetic light-harvesting proteins. Unfortunately, the intricacy of the natural complexes makes it very difficult to identify and isolate specific protein-pigment interactions that underlie the spectral-tuning mechanisms. Herein we identify and demonstrate the tuning mechanism of chlorophyll spectra in type II water-soluble chlorophyll binding proteins from Brassicaceae (WSCPs). By comparing the molecular structures of two natural WSCPs we correlate a shift in the chlorophyll red absorption band with deformation of its tetrapyrrole macrocycle that is induced by changing the position of a nearby tryptophan residue. We show by a set of reciprocal point mutations that this change accounts for up to 2/3 of the observed spectral shift between the two natural variants. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. High-resolution dynamic pressure sensor array based on piezo-phototronic effect tuned photoluminescence imaging.

    PubMed

    Peng, Mingzeng; Li, Zhou; Liu, Caihong; Zheng, Qiang; Shi, Xieqing; Song, Ming; Zhang, Yang; Du, Shiyu; Zhai, Junyi; Wang, Zhong Lin

    2015-03-24

    A high-resolution dynamic tactile/pressure display is indispensable to the comprehensive perception of force/mechanical stimulations such as electronic skin, biomechanical imaging/analysis, or personalized signatures. Here, we present a dynamic pressure sensor array based on pressure/strain tuned photoluminescence imaging without the need for electricity. Each sensor is a nanopillar that consists of InGaN/GaN multiple quantum wells. Its photoluminescence intensity can be modulated dramatically and linearly by small strain (0-0.15%) owing to the piezo-phototronic effect. The sensor array has a high pixel density of 6350 dpi and exceptional small standard deviation of photoluminescence. High-quality tactile/pressure sensing distribution can be real-time recorded by parallel photoluminescence imaging without any cross-talk. The sensor array can be inexpensively fabricated over large areas by semiconductor product lines. The proposed dynamic all-optical pressure imaging with excellent resolution, high sensitivity, good uniformity, and ultrafast response time offers a suitable way for smart sensing, micro/nano-opto-electromechanical systems.

  5. Using membrane composition to fine-tune the pKa of an optical liposome pH sensor.

    PubMed

    Clear, Kasey J; Virga, Katelyn; Gray, Lawrence; Smith, Bradley D

    2016-04-14

    Liposomes containing membrane-anchored pH-sensitive optical probes are valuable sensors for monitoring pH in various biomedical samples. The dynamic range of the sensor is maximized when the probe pKa is close to the expected sample pH. While some biomedical samples are close to neutral pH there are several circumstances where the pH is 1 or 2 units lower. Thus, there is a need to fine-tune the probe pKa in a predictable way. This investigation examined two lipid-conjugated optical probes, each with appended deep-red cyanine dyes containing indoline nitrogen atoms that are protonated in acid. The presence of anionic phospholipids in the liposomes stabilized the protonated probes and increased the probe pKa values by < 1 unit. The results show that rational modification of the membrane composition is a general non-covalent way to fine-tune the pKa of an optical liposome sensor for optimal pH sensing performance.

  6. The WD40 Domain Protein MSI1 Functions in a Histone Deacetylase Complex to Fine-Tune Abscisic Acid Signaling.

    PubMed

    Mehdi, Saher; Derkacheva, Maria; Ramström, Margareta; Kralemann, Lejon; Bergquist, Jonas; Hennig, Lars

    2016-01-01

    MSI1 belongs to a family of histone binding WD40-repeat proteins. Arabidopsis thaliana contains five genes encoding MSI1-like proteins, but their functions in diverse chromatin-associated complexes are poorly understood. Here, we show that MSI1 is part of a histone deacetylase complex. We copurified HISTONE DEACETYLASE19 (HDA19) with MSI1 and transcriptional regulatory SIN3-like proteins and provide evidence that MSI1 and HDA19 associate into the same complex in vivo. These data suggest that MSI1, HDA19, and HISTONE DEACETYLATION COMPLEX1 protein form a core complex that can integrate various SIN3-like proteins. We found that reduction of MSI1 or HDA19 causes upregulation of abscisic acid (ABA) receptor genes and hypersensitivity of ABA-responsive genes. The MSI1-HDA19 complex fine-tunes ABA signaling by binding to the chromatin of ABA receptor genes and by maintaining low levels of acetylation of histone H3 at lysine 9, thereby affecting the expression levels of ABA receptor genes. Reduced MSI1 or HDA19 levels led to increased tolerance to salt stress corresponding to the increased ABA sensitivity of gene expression. Together, our results reveal the presence of an MSI1-HDA19 complex that fine-tunes ABA signaling in Arabidopsis.

  7. The lesson of causal discovery algorithms for quantum correlations: causal explanations of Bell-inequality violations require fine-tuning

    NASA Astrophysics Data System (ADS)

    Wood, Christopher J.; Spekkens, Robert W.

    2015-03-01

    An active area of research in the fields of machine learning and statistics is the development of causal discovery algorithms, the purpose of which is to infer the causal relations that hold among a set of variables from the correlations that these exhibit . We apply some of these algorithms to the correlations that arise for entangled quantum systems. We show that they cannot distinguish correlations that satisfy Bell inequalities from correlations that violate Bell inequalities, and consequently that they cannot do justice to the challenges of explaining certain quantum correlations causally. Nonetheless, by adapting the conceptual tools of causal inference, we can show that any attempt to provide a causal explanation of nonsignalling correlations that violate a Bell inequality must contradict a core principle of these algorithms, namely, that an observed statistical independence between variables should not be explained by fine-tuning of the causal parameters. In particular, we demonstrate the need for such fine-tuning for most of the causal mechanisms that have been proposed to underlie Bell correlations, including superluminal causal influences, superdeterminism (that is, a denial of freedom of choice of settings), and retrocausal influences which do not introduce causal cycles.

  8. Expression analysis of aquaporins from desert truffle mycorrhizal symbiosis reveals a fine-tuned regulation under drought.

    PubMed

    Navarro-Ródenas, Alfonso; Bárzana, Gloria; Nicolás, Emilio; Carra, Andrea; Schubert, Andrea; Morte, Asunción

    2013-09-01

    We have performed the isolation, functional characterization, and expression analysis of aquaporins in roots and leaves of Helianthemum almeriense, in order to evaluate their roles in tolerance to water deficit. Five cDNAs, named HaPIP1;1, HaPIP1;2, HaPIP2;1, HaPIP2;2, and HaTIP1;1, were isolated from H. almeriense. A phylogenetic analysis of deduced proteins confirmed that they belong to the water channel proteins family. The HaPIP1;1, HaPIP2;1, and HaTIP1;1 genes encode functional water channel proteins, as indicated by expression assays in Saccharomyces cerevisiae, showing divergent roles in the transport of water, CO2, and NH3. The expression patterns of the genes isolated from H. almeriense and of a previously described gene from Terfezia claveryi (TcAQP1) were analyzed in mycorrhizal and nonmycorrhizal plants cultivated under well-watered or drought-stress conditions. Some of the studied aquaporins were subjected to fine-tuned expression only under drought-stress conditions. A beneficial effect on plant physiological parameters was observed in mycorrhizal plants with respect to nonmycorrhizal ones. Moreover, stress induced a change in the mycorrhizal type formed, which was more intracellular under drought stress. The combination of a high intracellular colonization, together with the fine-tuned expression of aquaporins could result in a morphophysiological adaptation of this symbiosis to drought conditions.

  9. Fine-tuning of xylose metabolism in genetically engineered Saccharomyces cerevisiae by scattered integration of xylose assimilation genes.

    PubMed

    Zuo, Qi; Zhao, Xin-Qing; Xiong, Liang; Liu, Hai-Jun; Xu, You-Hai; Hu, Shi-Yang; Ma, Zhong-Yi; Zhu, Qing-Wei; Bai, Feng-Wu

    2013-10-18

    Manipulation of multiple genes is a common experience in metabolic engineering and synthetic biology studies. Chromosome integration of multiple genes in one single position is always performed, however, there is so far no study on the integration of multiple genes separately in various positions (here in after referred to as "scattered integration") and its effect on fine-tuning of cellular metabolism. In this study, scattered integration of the xylose assimilation genes PsXR, PsXDH and ScXK was investigated in Saccharomyces cerevisiae, and transcription analysis of these genes as well as their enzyme activities were compared with those observed when the genes were integrated into one single site (defined as "tandem integration" here). Not only notable differences in transcription levels and enzyme activities were observed when the genes were integrated by the two strategies, but also change of the cofactor preference of PsXR gene was validated. Xylose fermentation was further studied with the strains developed with these strategies, and elevated xylose utilization rate was obtained in the scattered integration strain. These results proved that by positioning multiple genes on different chromosomes, fine-tuning of cellular metabolism could be achieved in recombinant S. cerevisiae.

  10. Observation of anticrossings in the exciton state of single quantum dots via electrical tuning of the fine-structure splitting

    NASA Astrophysics Data System (ADS)

    Pooley, M. A.; Bennett, A. J.; Stevenson, R. M.; Ward, M. B.; Patel, R. B.; Boyer de la Giroday, A.; Sköld, N.; Farrer, I.; Nicoll, C. A.; Ritchie, D. A.; Shields, A. J.

    2011-03-01

    Single quantum dots have many potential applications across the field of quantum computation, ranging from the generation of single photons or entangled photon pairs to the storage and manipulation of qubits. Single InAs quantum dots are optically active and thus can be used as an interface between photonic flying qubits and spin-based stationary qubits. Incorporating single InAs quantum dots into semiconductor devices allows the stationary qubits to be manipulated, making this system a promising candidate for quantum computation. It is well known that the exciton state of quantum dots is split into two polarisation dependent states; the energy difference between the states is the fine-structure splitting, (s). A vertical electric field has been used to tune |s| over a large range of ~ 100μeV, such that a dot which has |s| over 50μeV at zero field has been tuned to emit polarisation entangled photon pairs[1]. We observe coherent coupling between the two polarisation eigenstates. This coupling results in an anticrossing as the two states are tuned close to each other, and a rotation of the eigenstates through 90° as |s| is swept through its minimum value.

  11. Fine tuning of optical transition energy of twisted bilayer graphene via interlayer distance modulation

    NASA Astrophysics Data System (ADS)

    del Corro, Elena; Peña-Alvarez, Miriam; Sato, Kentaro; Morales-Garcia, Angel; Bousa, Milan; Mračko, Michal; Kolman, Radek; Pacakova, Barbara; Kavan, Ladislav; Kalbac, Martin; Frank, Otakar

    2017-02-01

    Twisted bilayer graphene (tBLG) represents a family of unique materials with optoelectronic properties tuned by the rotation angle between the two layers. The presented work shows an additional way of tweaking the electronic structure of tBLG by modifying the interlayer distance, for example by a small uniaxial out-of-plane compression. We have focused on the optical transition energy, which shows a clear dependence on the interlayer distance, both experimentally and theoretically.

  12. In situ fine tuning of bendable soft x-ray mirrors using a lateral shearing interferometer

    NASA Astrophysics Data System (ADS)

    Merthe, Daniel J.; Goldberg, Kenneth A.; Yashchuk, Valeriy V.; McKinney, Wayne R.; Celestre, Richard; Mochi, Iacopo; MacDougall, James; Morrison, Gregory Y.; Rekawa, Senajith B.; Anderson, Erik; Smith, Brian V.; Domning, Edward E.; Padmore, Howard

    2013-05-01

    Broadly applicable, in situ at-wavelength metrology methods for x-ray optics are currently under development at the Advanced Light Source. We demonstrate the use of quantitative wavefront feedback from a lateral shearing interferometer for the suppression of aberrations. With the high sensitivity provided by the interferometer we were able to optimally tune the bending couples of a single elliptical mirror (NA=2.7 mrad) in order to focus a beam of soft x-rays (1.24 keV) to a nearly diffraction-limited beam waist size of 156(±10) nm.

  13. Fine-tuning of atomic point charges: Classical simulations of pyridine in different environments

    NASA Astrophysics Data System (ADS)

    Macchiagodena, Marina; Mancini, Giordano; Pagliai, Marco; Del Frate, Gianluca; Barone, Vincenzo

    2017-06-01

    A correct description of electrostatic contributions in force fields for classical simulations is mandatory for an accurate modeling of molecular interactions in pure liquids or solutions. Here, we propose a new protocol for point charge fitting, aimed to take into the proper account different polarization effects due to the environment employing virtual sites and tuning the point charge within the polarizable continuum model framework. The protocol has been validated by means of molecular dynamics simulations on pure pyridine liquid and on pyridine aqueous solution, reproducing a series of experimental observables and providing the information for their correct interpretation at atomic level.

  14. Perspective. Extremely fine tuning of doping enabled by combinatorial molecular-beam epitaxy

    DOE PAGES

    Wu, J.; Bozovic, I.

    2015-04-06

    Chemical doping provides an effective method to control the electric properties of complex oxides. However, the state-of-art accuracy in controlling doping is limited to about 1%. This hampers elucidation of the precise doping dependences of physical properties and phenomena of interest, such as quantum phase transitions. Using the combinatorial molecular beam epitaxy, we improve the accuracy in tuning the doping level by two orders of magnitude. We illustrate this novel method by two examples: a systematic investigation of the doping dependence of interface superconductivity, and a study of the competing ground states in the vicinity of the insulator-to-superconductor transition.

  15. Perspective: Extremely fine tuning of doping enabled by combinatorial molecular-beam epitaxy

    SciTech Connect

    Wu, J.; Božović, I.

    2015-06-01

    Chemical doping provides an effective method to control the electric properties of complex oxides. However, the state-of-art accuracy in controlling doping is limited to about 1%. This hampers elucidation of the precise doping dependences of physical properties and phenomena of interest, such as quantum phase transitions. Using the combinatorial molecular beam epitaxy, we improve the accuracy in tuning the doping level by two orders of magnitude. We illustrate this novel method by two examples: a systematic investigation of the doping dependence of interface superconductivity, and a study of the competing ground states in the vicinity of the insulator-to-superconductor transition.

  16. Post-LHC7 fine-tuning in the minimal supergravity/CMSSM model with a 125 GeV Higgs boson

    NASA Astrophysics Data System (ADS)

    Baer, Howard; Barger, Vernon; Huang, Peisi; Mickelson, Dan; Mustafayev, Azar; Tata, Xerxes

    2013-02-01

    The recent discovery of a 125 GeV Higgs-like resonance at LHC, coupled with the lack of evidence for weak scale supersymmetry (SUSY), has severely constrained SUSY models such as minimal supergravity (mSUGRA)/CMSSM. As LHC probes deeper into SUSY model parameter space, the little hierarchy problem—how to reconcile the Z and Higgs boson mass scale with the scale of SUSY breaking—will become increasingly exacerbated unless a sparticle signal is found. We evaluate two different measures of fine-tuning in the mSUGRA/CMSSM model. The more stringent of these, ΔHS, includes effects that arise from the high-scale origin of the mSUGRA parameters while the second measure, ΔEW, is determined only by weak scale parameters: hence, it is universal to any model with the same particle spectrum and couplings. Our results incorporate the latest constraints from LHC7 sparticle searches, LHCb limits from Bs→μ+μ- and also require a light Higgs scalar with mh˜123-127GeV. We present fine-tuning contours in the m0 vs m1/2 plane for several sets of A0 and tan⁡β values. We also present results for ΔHS and ΔEW from a scan over the entire viable model parameter space. We find a ΔHS≳103, or at best 0.1%, fine-tuning. For the less stringent electroweak fine-tuning, we find ΔEW≳102, or at best 1%, fine-tuning. Two benchmark points are presented that have the lowest values of ΔHS and ΔEW. Our results provide a quantitative measure for ascertaining whether or not the remaining mSUGRA/CMSSM model parameter space is excessively fine-tuned and so could provide impetus for considering alternative SUSY models.

  17. Enhanced processing in arrays of optimally tuned nonlinear biomimetic sensors: A coupling-mediated Ringelmann effect and its dynamical mitigation

    NASA Astrophysics Data System (ADS)

    Nikitin, Alexander P.; Bulsara, Adi R.; Stocks, Nigel G.

    2017-03-01

    Inspired by recent results on self-tunability in the outer hair cells of the mammalian cochlea, we describe an array of magnetic sensors where each individual sensor can self-tune to an optimal operating regime. The self-tuning gives the array its "biomimetic" features. We show that the overall performance of the array can, as expected, be improved by increasing the number of sensors but, however, coupling between sensors reduces the overall performance even though the individual sensors in the system could see an improvement. We quantify the similarity of this phenomenon to the Ringelmann effect that was formulated 103 years ago to account for productivity losses in human and animal groups. We propose a global feedback scheme that can be used to greatly mitigate the performance degradation that would, normally, stem from the Ringelmann effect.

  18. Functional Role of PPARs in Ruminants: Potential Targets for Fine-Tuning Metabolism during Growth and Lactation

    PubMed Central

    Chen, Shuowen; Khan, Muhammad J.; Loor, Juan J.

    2013-01-01

    Characterization and biological roles of the peroxisome proliferator-activated receptor (PPAR) isotypes are well known in monogastrics, but not in ruminants. However, a wealth of information has accumulated in little more than a decade on ruminant PPARs including isotype tissue distribution, response to synthetic and natural agonists, gene targets, and factors affecting their expression. Functional characterization demonstrated that, as in monogastrics, the PPAR isotypes control expression of genes involved in lipid metabolism, anti-inflammatory response, development, and growth. Contrary to mouse, however, the PPARγ gene network appears to controls milk fat synthesis in lactating ruminants. As in monogastrics, PPAR isotypes in ruminants are activated by long-chain fatty acids, therefore, making them ideal candidates for fine-tuning metabolism in this species via nutrients. In this regard, using information accumulated in ruminants and monogastrics, we propose a model of PPAR isotype-driven biological functions encompassing key tissues during the peripartal period in dairy cattle. PMID:23737762

  19. Single Heteroatom Fine-Tuning of the Emissive Properties in Organoboron Complexes with 7-(Azaheteroaryl)indole Systems.

    PubMed

    Más-Montoya, Miriam; Usea, Laura; Espinosa Ferao, Arturo; Montenegro, María F; Ramírez de Arellano, Carmen; Tárraga, Alberto; Rodríguez-López, José N; Curiel, David

    2016-04-15

    The application of organoboron compounds as light-absorbing or light-emitting species in areas as relevant as organic electronics or biomedicine has motivated the search for new materials which contribute to the progress of those applications. This article reports the synthesis of four-coordinate boron complexes based on the unexplored 7-(azaheteroaryl)indole ligands. An easy synthetic approach has enabled the fine-tuning of the electronic structure of the organoboron species by modifying a heteroaromatic component in the conjugated system. Furthermore, a comprehensive characterization by X-ray diffraction, absorption and emission spectroscopy, both in solution and in the solid state, cyclic voltammetry, and computational methods has evidenced the utility of this simple strategy. Large Stokes shifts have been achieved in solid thin-films which show a range of emitted light from blue to orange. The synthesized compounds have been used as biocompatible fluorophores in cell bioimaging.

  20. Fine-tuning the electrostatic properties of an alkali-linked organic adlayer on a metal substrate.

    PubMed

    Floris, Andrea; Comisso, Alessio; De Vita, Alessandro

    2013-09-24

    The performance of modern organic electronic devices is often determined by the electronic level alignment at a metal-organic interface. This property can be controlled by introducing an interfacial electrostatic dipole via the insertion of a stable interlayer between the metallic and the organic phases. Here, we use density functional theory to investigate the electrostatic properties of an assembled structure formed by alkali metals coadsorbed with 7,7,8,8-tetracyanoquinodimethane (TCNQ) molecules on a Ag(100) substrate. We find that the interfacial dipole buildup is regulated by the interplay of adsorption energetics, steric constraints and charge transfer effects, so that choosing chemical substitutions within TCNQ and different alkali metals provides a rich playground to control the systems' electrostatics and in particular fine-tune its work-function shift.

  1. Fine-tuning of a radical-based reaction by radical S-adenosyl-L-methionine tryptophan lyase.

    PubMed

    Sicoli, Giuseppe; Mouesca, Jean-Marie; Zeppieri, Laura; Amara, Patricia; Martin, Lydie; Barra, Anne-Laure; Fontecilla-Camps, Juan C; Gambarelli, Serge; Nicolet, Yvain

    2016-03-18

    The radical S-adenosyl-L-methionine tryptophan lyase NosL converts L-tryptophan into 3-methylindolic acid, which is a precursor in the synthesis of the thiopeptide antibiotic nosiheptide. Using electron paramagnetic resonance spectroscopy and multiple L-tryptophan isotopologues, we trapped and characterized radical intermediates that indicate a carboxyl fragment migration mechanism for NosL. This is in contrast to a proposed fragmentation-recombination mechanism that implied Cα-Cβ bond cleavage of L-tryptophan. Although NosL resembles related tyrosine lyases, subtle substrate motions in its active site are responsible for a fine-tuned radical chemistry, which selects the Cα-C bond for disruption. This mechanism highlights evolutionary adaptation to structural constraints in proteins as a route to alternative enzyme function. Copyright © 2016, American Association for the Advancement of Science.

  2. Knowledge based functions for routine use at a German university hospital setting: the issue of fine tuning.

    PubMed Central

    Bürkle, T.; Prokosch, H. U.; Hussak, G.; Dudeck, J.

    1997-01-01

    In this paper we present the introduction of knowledge based functions into clinical routine at Giessen University Hospital. For this purpose a therapy planning module at the medical intensive care unit has been extensively redesigned in order to support the structured documentation of drug prescriptions. After introduction of this new HIS component in January 1996 research has been initiated to establish a basic drug therapy knowledge base. The main components of a knowledge based system have been fully incorporated into the hospital information system WING and are in routine use since December 1996. During a pre-production phase warnings of reminder functions were logged and reviewed by an interdisciplinary team in order to adapt the system to the actual clinical environment. The paper describes experiences during this fine tuning and adaptation process which was necessary to bring a small set of knowledge modules into clinical routine. PMID:9357589

  3. Fine-tuning of process conditions to improve product uniformity of polystyrene particles used for wind tunnel velocimetry

    NASA Technical Reports Server (NTRS)

    Ray, Asit K.

    1990-01-01

    Monodisperse polymer particles (having uniform diameter) were used for the last two decades in physical, biological, and chemical sciences. In NASA Langley Research Center monodisperse polystyrene particles are used in wind tunnel laser velocimeters. These polystyrene (PS) particles in latex form were formulated at the Engineering Laboratory of FENGD using emulsion-free emulsion polymerization. Monodisperse PS latices particles having different particle diameters were formulated and useful experimental data involving effects of process conditions on particle size were accumulated. However, similar process conditions and chemical recipes for polymerization of styrene monomer have often yielded monodisperse particles having varying diameters. The purpose was to improve the PS latex product uniformity by fine-tuning the process parameters based on the knowledge of suspension and emulsion polymerization.

  4. MicroRNA inhibition fine-tunes and provides robustness to the restriction point switch of the cell cycle

    PubMed Central

    del Rosario, Ricardo C. H.; Damasco, Joseph Ray Clarence G.; Aguda, Baltazar D.

    2016-01-01

    The restriction point marks a switch in G1 from growth factor-dependent to growth factor-independent progression of the cell cycle. The proper regulation of this switch is important for normal cell processes; aberrations could result in a number of diseases such as cancer, neurodegenerative disorders, stroke and myocardial infarction. To further understand the regulation of the restriction point, we extended a mathematical model of the Rb-E2F pathway to include members of the microRNA cluster miR-17-92. Our mathematical analysis shows that microRNAs play an essential role in fine-tuning and providing robustness to the switch. We also demonstrate how microRNA regulation can steer cells in or out of cancer states. PMID:27610602

  5. Gap orientation tuning in split ring resonator array for increased energy absorption

    NASA Astrophysics Data System (ADS)

    Ji, Liming; Varadan, Vasundara V.

    2017-06-01

    Metamaterials have been proposed for absorber application. The research on absorber design has been highly focused on the design of each unit that is periodically laid out in an array. In this study, we present the layout of a unit structure as a new tuning factor for absorber performance based on the analysis of split ring resonator (SRR) resonances. Gap orientation of each SRR is the only variable in this approach. Simulation results show that random gap orientation layout exhibits much higher energy absorption compared to the other designs with periodic gap orientations. This significant absorption enhancement is neither due to a particular gap orientation nor due to the dimension of each SRR. Instead, it is due to the combination of the different gap orientations, which generates a particular layout for high energy absorption. The major part of absorbed energy goes to dielectric loss in substrate. The layout with high energy absorption creates higher localized electric field intensity that permeates into the substrate. We also present a new design that is periodically laid out but have four specially oriented SRRs in each unit "super cell". The periodicity of this super cell is easier to design since it is much more economical to simulate than randomly oriented SRRs. The maximum absorption of the super cell design is 80%, which is much higher than the other designs with the single SRR orientation. The high energy absorption of the super cell design proves that orientation of SRRs within a unit cell, a "supercell" can be a very useful tuning factor.

  6. Fine frequency tuning in sum-frequency generation of continuous-wave single-frequency coherent light at 252 nm with dual-wavelength enhancement.

    PubMed

    Kumagai, Hiroshi

    2007-01-01

    Fine frequency tuning of the deep-ultraviolet single-mode coherent light at 252 nm was conducted through the PID feedback system automatically by changing the temperature of a beta-BaB(2)O(4) (BBO) crystal in a doubly resonant external cavity for the sum-frequency mixing of 373 and 780 nm light. The temperature-dependent frequency tuning rate is 19.3 MHzK(-1), which is sufficiently fine to realize the laser cooling of neutral silicon atoms because the natural width of the laser cooling transition is 28.8 MHz.

  7. Fine-tuning the onset of myogenesis by homeobox proteins that interact with the Myf5 limb enhancer.

    PubMed

    Daubas, Philippe; Duval, Nathalie; Bajard, Lola; Langa Vives, Francina; Robert, Benoît; Mankoo, Baljinder S; Buckingham, Margaret

    2015-11-04

    Skeletal myogenesis in vertebrates is initiated at different sites of skeletal muscle formation during development, by activation of specific control elements of the myogenic regulatory genes. In the mouse embryo, Myf5 is the first myogenic determination gene to be expressed and its spatiotemporal regulation requires multiple enhancer sequences, extending over 120 kb upstream of the Mrf4-Myf5 locus. An enhancer, located at -57/-58 kb from Myf5, is responsible for its activation in myogenic cells derived from the hypaxial domain of the somite, that will form limb muscles. Pax3 and Six1/4 transcription factors are essential activators of this enhancer, acting on a 145-bp core element. Myogenic progenitor cells that will form the future muscle masses of the limbs express the factors necessary for Myf5 activation when they delaminate from the hypaxial dermomyotome and migrate into the forelimb bud, however they do not activate Myf5 and the myogenic programme until they have populated the prospective muscle masses. We show that Msx1 and Meox2 homeodomain-containing transcription factors bind in vitro and in vivo to specific sites in the 145-bp element, and are implicated in fine-tuning activation of Myf5 in the forelimb. Msx1, when bound between Pax and Six sites, prevents the binding of these key activators, thus inhibiting transcription of Myf5 and consequent premature myogenic differentiation. Meox2 is required for Myf5 activation at the onset of myogenesis via direct binding to other homeodomain sites in this sequence. Thus, these homeodomain factors, acting in addition to Pax3 and Six1/4, fine-tune the entry of progenitor cells into myogenesis at early stages of forelimb development.

  8. Competitive Coordination Strategy to Finely Tune Pore Environment of Zirconium-Based Metal-Organic Frameworks.

    PubMed

    He, Ting; Ni, Bing; Xu, Xiaobin; Li, Haoyi; Lin, Haifeng; Yuan, Wenjuan; Luo, Jun; Hu, Wenping; Wang, Xun

    2017-07-12

    Metal-organic frameworks (MOFs) are a class of crystalline porous materials with reticular architectures. Precisely tuning pore environment of MOFs has drawn tremendous attention but remains a great challenge. In this work, we demonstrate a competitive coordination approach to synthesize a series of zirconium-metalloporphyrinic MOFs through introducing H2O and monocarboxylic acid as modulating reagents, in which well-ordered mesoporous channels could be observed clearly under conventional transmission electron microscopy. Owing to plenty of unsaturated Lewis acid catalytic sites exposed in the visualized mesoporous channels, these structures exhibit outstanding catalytic activity and excellent stability in the chemical fixation of carbon dioxide to cyclic carbonates. The zirconium-based MOFs with ordered channel structures are expected to pave the way to expand the potential applications of MOFs.

  9. Fine tuning a well-oiled machine: Influence of NK1.1 and NKG2D on NKT cell development and function

    PubMed Central

    Joshi, Sunil K.; Lang, Mark L.

    2013-01-01

    Natural Killer T cells (NKT) represent a group of CD1d-restricted T-lineage cells that that provide a functional interface between innate and adaptive immune responses in infectious disease, cancer, allergy and autoimmunity. There have been remarkable advances in understanding the molecular events that underpin NKT development in the thymus and in the complex array of functions in the periphery. Most functional studies have focused on activation of T cell antigen receptors expressed by NKT cells and their responses to CD1d presentation of glycolipid and related antigens. Receiving less attention has been several molecules that are hallmarks of Natural Killer (NK) cells, but nonetheless expressed by NKT cells. These include several activating and inhibitory receptors that may fine-tune NKT development and survival, as well as activation via antigen receptors. Herein, we review the possible roles of the NK1.1 and NKG2D receptors in regulating development and function of NKT cells in health and disease. We suggest that pharmacological alteration of NKT activity should consider the potential complexities commensurate with NK1.1 and NKG2D expression. PMID:23800654

  10. Fine-Tuning of the Actin Cytoskeleton and Cell Adhesion During Drosophila Development by the Unconventional Guanine Nucleotide Exchange Factors Myoblast City and Sponge.

    PubMed

    Biersmith, Bridget; Wang, Zong-Heng; Geisbrecht, Erika R

    2015-06-01

    The evolutionarily conserved Dock proteins function as unconventional guanine nucleotide exchange factors (GEFs). Upon binding to engulfment and cell motility (ELMO) proteins, Dock-ELMO complexes activate the Rho family of small GTPases to mediate a diverse array of biological processes, including cell motility, apoptotic cell clearance, and axon guidance. Overlapping expression patterns and functional redundancy among the 11 vertebrate Dock family members, which are subdivided into four families (Dock A, B, C, and D), complicate genetic analysis. In both vertebrate and invertebrate systems, the actin dynamics regulator, Rac, is the target GTPase of the Dock-A subfamily. However, it remains unclear whether Rac or Rap1 are the in vivo downstream GTPases of the Dock-B subfamily. Drosophila melanogaster is an excellent genetic model organism for understanding Dock protein function as its genome encodes one ortholog per subfamily: Myoblast city (Mbc; Dock A) and Sponge (Spg; Dock B). Here we show that the roles of Spg and Mbc are not redundant in the Drosophila somatic muscle or the dorsal vessel. Moreover, we confirm the in vivo role of Mbc upstream of Rac and provide evidence that Spg functions in concert with Rap1, possibly to regulate aspects of cell adhesion. Together these data show that Mbc and Spg can have different downstream GTPase targets. Our findings predict that the ability to regulate downstream GTPases is dependent on cellular context and allows for the fine-tuning of actin cytoskeletal or cell adhesion events in biological processes that undergo cell morphogenesis.

  11. Fine-Tuning of the Actin Cytoskeleton and Cell Adhesion During Drosophila Development by the Unconventional Guanine Nucleotide Exchange Factors Myoblast City and Sponge

    PubMed Central

    Biersmith, Bridget; Wang, Zong-Heng; Geisbrecht, Erika R.

    2015-01-01

    The evolutionarily conserved Dock proteins function as unconventional guanine nucleotide exchange factors (GEFs). Upon binding to engulfment and cell motility (ELMO) proteins, Dock–ELMO complexes activate the Rho family of small GTPases to mediate a diverse array of biological processes, including cell motility, apoptotic cell clearance, and axon guidance. Overlapping expression patterns and functional redundancy among the 11 vertebrate Dock family members, which are subdivided into four families (Dock A, B, C, and D), complicate genetic analysis. In both vertebrate and invertebrate systems, the actin dynamics regulator, Rac, is the target GTPase of the Dock-A subfamily. However, it remains unclear whether Rac or Rap1 are the in vivo downstream GTPases of the Dock-B subfamily. Drosophila melanogaster is an excellent genetic model organism for understanding Dock protein function as its genome encodes one ortholog per subfamily: Myoblast city (Mbc; Dock A) and Sponge (Spg; Dock B). Here we show that the roles of Spg and Mbc are not redundant in the Drosophila somatic muscle or the dorsal vessel. Moreover, we confirm the in vivo role of Mbc upstream of Rac and provide evidence that Spg functions in concert with Rap1, possibly to regulate aspects of cell adhesion. Together these data show that Mbc and Spg can have different downstream GTPase targets. Our findings predict that the ability to regulate downstream GTPases is dependent on cellular context and allows for the fine-tuning of actin cytoskeletal or cell adhesion events in biological processes that undergo cell morphogenesis. PMID:25908317

  12. Fine-tuning of proximal TCR signaling by ZAP-70 tyrosine residues in Jurkat cells.

    PubMed

    Szabo, M; Czompoly, T; Kvell, K; Talaber, G; Bartis, D; Nemeth, P; Berki, T; Boldizsar, F

    2012-02-01

    Zeta-chain-associated protein kinase of 70kDa (ZAP-70) kinase is a key regulator in the early steps of TCR signaling but some aspects of its fine regulation are still unclear. From its 31 tyrosine (Y) residues, 11 phosphorylation sites have been identified, some with activator (Y315 and Y493) or inhibitory (Y292 and Y492) and others with unknown function (Y069, Y126 and Y178). In our present work, we aimed to elucidate the role of different Y residues of ZAP-70, especially those with unknown function, in calcium signaling and the autoregulation of the kinase. ZAP-70-deficient Jurkat cells (P116) were stably reconstituted with point-mutated ZAP-70 constructs where tyrosine residues 069, 126, 178, 238, 292, 315, 492 or 493 were replaced with phenylalanine (F). The anti-CD3-elicited calcium signal increased in F069-, F292- and F492-ZAP-70-expressing cell lines but decreased in the F126-, F315- and F493-ZAP-70-expressing cell lines. ZAP-70 point mutations led to phosphorylation changes predominantly in SH2 domain containing leukocyte protein of 76kDa (SLP-76) but not linker of activated T cells (LAT) during CD3-activation; moreover, we detected basal hyperphosphorylation of SLP-76 Y128 in the F126-, F178- and F492-ZAP-70-expressing cell lines. In summary, Y069, Y178, Y292 and Y492 have inhibitory, while Y126, Y315 and Y493 activator role in anti-CD3-induced T-cell activation. Phosphorylation changes in LAT and SLP-76 suggest that fine regulation of ZAP-70 on calcium signaling is rather transmitted through SLP-76 not LAT. Additionally, negative or positive autoregulatory function of Y292 and Y493 or Y315, respectively, was revealed in ZAP-70. These data indicate that previously not characterized Y069, Y126 and Y178 in ZAP-70 participate in the fine regulation of TCR signaling.

  13. Self-assembly based plasmonic arrays tuned by atomic layer deposition for extreme visible light absorption.

    PubMed

    Hägglund, Carl; Zeltzer, Gabriel; Ruiz, Ricardo; Thomann, Isabell; Lee, Han-Bo-Ram; Brongersma, Mark L; Bent, Stacey F

    2013-07-10

    Achieving complete absorption of visible light with a minimal amount of material is highly desirable for many applications, including solar energy conversion to fuel and electricity, where benefits in conversion efficiency and economy can be obtained. On a fundamental level, it is of great interest to explore whether the ultimate limits in light absorption per unit volume can be achieved by capitalizing on the advances in metamaterial science and nanosynthesis. Here, we combine block copolymer lithography and atomic layer deposition to tune the effective optical properties of a plasmonic array at the atomic scale. Critical coupling to the resulting nanocomposite layer is accomplished through guidance by a simple analytical model and measurements by spectroscopic ellipsometry. Thereby, a maximized absorption of light exceeding 99% is accomplished, of which up to about 93% occurs in a volume-equivalent thickness of gold of only 1.6 nm. This corresponds to a record effective absorption coefficient of 1.7 × 10(7) cm(-1) in the visible region, far exceeding those of solid metals, graphene, dye monolayers, and thin film solar cell materials. It is more than a factor of 2 higher than that previously obtained using a critically coupled dye J-aggregate, with a peak width exceeding the latter by 1 order of magnitude. These results thereby substantially push the limits for light harvesting in ultrathin, nanoengineered systems.

  14. Over 11% Efficiency in Tandem Polymer Solar Cells Featured by a Low-Band-Gap Polymer with Fine-Tuned Properties.

    PubMed

    Zheng, Zhong; Zhang, Shaoqing; Zhang, Jianqi; Qin, Yunpeng; Li, Wanning; Yu, Runnan; Wei, Zhixiang; Hou, Jianhui

    2016-07-01

    Highly efficient polymer solar cells with tandem structure are fabricated by using two excellent photovoltaic polymers and a highly transparent intermediate recombination layer. Power conversion efficiencies over 11% can be realized featured by a low-band-gap polymer with fine-tuned properties.

  15. Rational diversification of a promoter providing fine-tuned expression and orthogonal regulation for synthetic biology.

    PubMed

    Blount, Benjamin A; Weenink, Tim; Vasylechko, Serge; Ellis, Tom

    2012-01-01

    Yeast is an ideal organism for the development and application of synthetic biology, yet there remain relatively few well-characterised biological parts suitable for precise engineering of this chassis. In order to address this current need, we present here a strategy that takes a single biological part, a promoter, and re-engineers it to produce a fine-graded output range promoter library and new regulated promoters desirable for orthogonal synthetic biology applications. A highly constitutive Saccharomyces cerevisiae promoter, PFY1p, was identified by bioinformatic approaches, characterised in vivo and diversified at its core sequence to create a 36-member promoter library. TetR regulation was introduced into PFY1p to create a synthetic inducible promoter (iPFY1p) that functions in an inverter device. Orthogonal and scalable regulation of synthetic promoters was then demonstrated for the first time using customisable Transcription Activator-Like Effectors (TALEs) modified and designed to act as orthogonal repressors for specific PFY1-based promoters. The ability to diversify a promoter at its core sequences and then independently target Transcription Activator-Like Orthogonal Repressors (TALORs) to virtually any of these sequences shows great promise toward the design and construction of future synthetic gene networks that encode complex "multi-wire" logic functions.

  16. Rational Diversification of a Promoter Providing Fine-Tuned Expression and Orthogonal Regulation for Synthetic Biology

    PubMed Central

    Blount, Benjamin A.; Weenink, Tim; Vasylechko, Serge; Ellis, Tom

    2012-01-01

    Yeast is an ideal organism for the development and application of synthetic biology, yet there remain relatively few well-characterised biological parts suitable for precise engineering of this chassis. In order to address this current need, we present here a strategy that takes a single biological part, a promoter, and re-engineers it to produce a fine-graded output range promoter library and new regulated promoters desirable for orthogonal synthetic biology applications. A highly constitutive Saccharomyces cerevisiae promoter, PFY1p, was identified by bioinformatic approaches, characterised in vivo and diversified at its core sequence to create a 36-member promoter library. TetR regulation was introduced into PFY1p to create a synthetic inducible promoter (iPFY1p) that functions in an inverter device. Orthogonal and scalable regulation of synthetic promoters was then demonstrated for the first time using customisable Transcription Activator-Like Effectors (TALEs) modified and designed to act as orthogonal repressors for specific PFY1-based promoters. The ability to diversify a promoter at its core sequences and then independently target Transcription Activator-Like Orthogonal Repressors (TALORs) to virtually any of these sequences shows great promise toward the design and construction of future synthetic gene networks that encode complex “multi-wire” logic functions. PMID:22442681

  17. Fine-tuning transmission electron microscopy methods to evaluate the cellular architecture of Ulvacean seaweeds (Chlorophyta).

    PubMed

    Farias, D R; Simioni, C; Poltronieri, E; Bouzon, Z L; Macleod, C K

    2017-02-20

    Chemical fixation is a critical step in the analysis of the ultrastructure of seaweeds because the wrong approach can compromise the ability to distinguish fine-scale cellular composition. Fixation agents, fixation time and type of tissue are important factors to consider for transmission electron microscopy (TEM), and not every protocol is suitable for all cell types. We evaluated a range of fixation agents, post-fixation time and dehydration solutions to determine a TEM protocol for seaweeds in the Family Ulvaceae. We assessed Ulva lactuca using 5 protocols. The level of preservation obtained differed markedly between fixation methods The best result was obtained by fixing the sample with 2.5% glutaraldehyde, 0.05M sodium cacodylate buffer and 2% paraformaldehyde overnight, and 8h post-fixation in 1% in osmium tetroxide 1%. This approach and fixation time ensured that the membranes, especially the thylakoid membranes of chloroplasts, remained intact. Ethanol is recommended for dehydration as the use of acetone for dehydration resulted in the collapse of cellular membranes. This new protocol will ensure the ultrastructure of Ulvacean seaweeds can be clearly ascertained in the future.

  18. Scaling behavior of the magnetic-field-tuned superconductor-insulator transition in two-dimensional Josephson-junction arrays

    SciTech Connect

    Chen, C.D.; Delsing, P.; Haviland, D.B.; Harada, Y.; Claeson, T.

    1995-06-01

    We have studied the superconductor-insulator (SI) phase transition for two-dimensional (2D) arrays of small Josephson junctions in a weak magnetic field. The data were analyzed within the context of the theory of the magnetic-field-tuned SI transition in 2D superconductors. We show resistance scaling curves over several orders of magnitude for the 2D arrays. The critical exponent {ital z}{sub {ital B}} is determined to be 1.05, in good agreement with the theory. Moreover, the transverse (Hall) resistance at the critical field is found to be very small in comparison to the longitudinal resistance.

  19. Fine tuning the heavy fermion ground state: A new handle on cerium cobalt indium

    NASA Astrophysics Data System (ADS)

    Pham, Long D.

    A Two Fluid Description of the Kondo Lattice CeCoIn5 has been extended to include additional entropy terms that were not considered in the original work by S. Nakatsuji et al. [1]. The use of a Matlab computer code was successful at iteratively solving for f, the fraction of itinerant interacting heavy quasiparticles, and showed that it converges to a temperature dependent function invariant under successive iterations. The linear specific heat coefficient, gamma, was extracted from transport consideration in conjunction with f(T) and the Kadowacki-Woods ratio to be 204mJ/mole-K2, in good agreement from heat capacity measurements of 290mJ/mole-K2 for CeCoIn 5 [32]. Antiferromagnetism has been induced in CeCoIn5 as well as its two isostructural, isovalent sister compounds CeRhIn5 and CeIrIn 5. Cadmium-doping the heavy-fermion superconductor CeCoIn5 at the percent level acts as an electronic tuning agent, sensitively shifting the balance between superconductivity and antiferromagnetism and opening new ambient-pressure phase space in the study of heavy-fermion ground states. At nominal concentrations of x>0.070, CeCo(In1-xCd x)5 displays a two phase region of antiferromagnetism coexisting with superconductivity up to x<0.15, above which no trace of superconductivity persists in specific heat. Similar results was seen in CeIr(In1-xCd x)5 where a quantum critical point (QCP) was observed, separating superconductivity from antiferromagnetism at a nominal critical concentration of x≈0.0475, while CeRh(In1-xCdx)5 goes through an incommensurate to commensurate antiferromagnetic transition nominally at x≈0.10. Amazingly, pressure completely recovers Tc in CeCo(In1-x Cdx)5 measured at nominal concentrations of x=0.10, and 0.15. Phase diagrams were constructed from specific heat and confirmed with resistivity and magnetization. An introduction to strongly correlated physics, relevant to the 115 family, will be worked out followed by a description of general techniques of

  20. Tomato Yield Heterosis Is Triggered by a Dosage Sensitivity of the Florigen Pathway That Fine-Tunes Shoot Architecture

    PubMed Central

    Jiang, Ke; Liberatore, Katie L.; Park, Soon Ju; Alvarez, John P.; Lippman, Zachary B.

    2013-01-01

    The superiority of hybrids has long been exploited in agriculture, and although many models explaining “heterosis” have been put forth, direct empirical support is limited. Particularly elusive have been cases of heterozygosity for single gene mutations causing heterosis under a genetic model known as overdominance. In tomato (Solanum lycopersicum), plants carrying mutations in SINGLE FLOWER TRUSS (SFT) encoding the flowering hormone florigen are severely delayed in flowering, become extremely large, and produce few flowers and fruits, but when heterozygous, yields are dramatically increased. Curiously, this overdominance is evident only in the background of “determinate” plants, in which the continuous production of side shoots and inflorescences gradually halts due to a defect in the flowering repressor SELF PRUNING (SP). How sp facilitates sft overdominance is unclear, but is thought to relate to the opposing functions these genes have on flowering time and shoot architecture. We show that sft mutant heterozygosity (sft/+) causes weak semi-dominant delays in flowering of both primary and side shoots. Using transcriptome sequencing of shoot meristems, we demonstrate that this delay begins before seedling meristems become reproductive, followed by delays in subsequent side shoot meristems that, in turn, postpone the arrest of shoot and inflorescence production. Reducing SFT levels in sp plants by artificial microRNAs recapitulates the dose-dependent modification of shoot and inflorescence production of sft/+ heterozygotes, confirming that fine-tuning levels of functional SFT transcripts provides a foundation for higher yields. Finally, we show that although flowering delays by florigen mutant heterozygosity are conserved in Arabidopsis, increased yield is not, likely because cyclical flowering is absent. We suggest sft heterozygosity triggers a yield improvement by optimizing plant architecture via its dosage response in the florigen pathway. Exploiting

  1. Tuning the self-assembly of surfactants by the confinement of carbon nanotube arrays: a cornucopia of lamellar phase variants

    NASA Astrophysics Data System (ADS)

    Li, Zhen; Wang, Pan; Ma, Yunyun; Zhang, Jun; Dai, Caili; Yan, Youguo; Liu, Bing

    2015-03-01

    Tuning the self-assembly of building blocks to obtain a kaleidoscope of nanostructures is very important and challenging for the preparation of advanced nanomaterials. Amphiphiles confined within carbon nanotube (CNT) arrays can self-assemble into complex structures that maintain the ``bilayer'' characteristic of a lamellar phase, we call them ``lamellar phase variants (LPVs)''. In this work, we carried out coarse-grained molecular dynamics (MD) studies to uncover novel LPVs. By varying the pattern of a CNT array, we obtained the ``bilayer tube (BT) series'', which contains circular, hexagonal, octagonal, and elliptical nanotubes. Furthermore, by introducing dislocation to CNT arrays, we obtained the ``bilayer scroll (BS) series'' that contains polymorphic nano-scrolls. These nanostructures are very novel and intriguing. To gain insights into the formation of LPVs, we studied the morphology evolution, which was demonstrated to be an unfamiliar ``successive self-assembly process''. These unusual self-assembling nanostructures and the formation process could provide clues for further studies on tuning the self-assembly of building blocks. The strategies developed in this work to obtain novel nanostructures are expected to facilitate the design and fabrication of nano-devices.Tuning the self-assembly of building blocks to obtain a kaleidoscope of nanostructures is very important and challenging for the preparation of advanced nanomaterials. Amphiphiles confined within carbon nanotube (CNT) arrays can self-assemble into complex structures that maintain the ``bilayer'' characteristic of a lamellar phase, we call them ``lamellar phase variants (LPVs)''. In this work, we carried out coarse-grained molecular dynamics (MD) studies to uncover novel LPVs. By varying the pattern of a CNT array, we obtained the ``bilayer tube (BT) series'', which contains circular, hexagonal, octagonal, and elliptical nanotubes. Furthermore, by introducing dislocation to CNT arrays, we obtained

  2. Fine-tuning of synaptic upscaling at excitatory synapses by endocannabinoid signaling is mediated via the CB1 receptor

    PubMed Central

    Song, Yunping; Zhang, Jian; Chen, Chu

    2015-01-01

    The endocannabinoid 2-arachidonoylglycerol (2-AG) functions as a retrograde signaling molecule mediating synaptic transmission and plasticity at both inhibitory and excitatory synapses. However, little is known about whether 2-AG signaling is involved in homeostatic regulation of miniature synaptic events at excitatory synapses in response to activity deprivation. Here, we report that chronic blockade of firing by tetrodotoxin (TTX) for two days resulted in increases both in the frequency and amplitude of spontaneous miniature excitatory postsynaptic currents (mEPSCs) in cultured mouse hippocampal neurons. However, treatment with 2-AG alone or JZL184, a potent and selective inhibitor for monoacylglycerol lipase (MAGL) that hydrolyzes 2-AG, induced a CB1 receptor-dependent reduction of the frequency of mEPSCs, but not the amplitude. The TTX-increased frequency was blunted by 2-AG or JZL184 and this effect was eliminated by pharmacological or genetic inhibition of CB1 receptors. In addition, TTX still increased frequency and amplitude of mEPSCs in the presence of CB1 receptor inhibition. Our results suggest that while endocannabinoids are not required for induction of synaptic scaling at excitatory glutamate synapses after chronic activity deprivation, 2-AG signaling may play a role in fine-tuning of synaptic strengths via presynaptically-expressed CB1 receptors. PMID:26541090

  3. 5-Azacytidine-induced Protein 2 (AZI2) Regulates Bone Mass by Fine-tuning Osteoclast Survival*

    PubMed Central

    Maruyama, Kenta; Fukasaka, Masahiro; Uematsu, Satoshi; Takeuchi, Osamu; Kondo, Takeshi; Saitoh, Tatsuya; Martino, Mikaël M.; Akira, Shizuo

    2015-01-01

    5-Azacytidine-induced protein 2 (AZI2) is a TNF receptor (TNFR)-associated factor family member-associated NF-κB activator-binding kinase 1-binding protein that regulates the production of IFNs. A previous in vitro study showed that AZI2 is involved in dendritic cell differentiation. However, the roles of AZI2 in immunity and its pleiotropic functions are unknown in vivo. Here we report that AZI2 knock-out mice exhibit normal dendritic cell differentiation in vivo. However, we found that adult AZI2 knock-out mice have severe osteoporosis due to increased osteoclast longevity. We revealed that the higher longevity of AZI2-deficient osteoclasts is due to an augmented activation of proto-oncogene tyrosine-protein kinase Src (c-Src), which is a critical player in osteoclast survival. We found that AZI2 inhibits c-Src activity by regulating the activation of heat shock protein 90 (Hsp90), a chaperone involved in c-Src dephosphorylation. Furthermore, we demonstrated that AZI2 indirectly inhibits c-Src by interacting with the Hsp90 co-chaperone Cdc37. Strikingly, administration of a c-Src inhibitor markedly prevented bone loss in AZI2 knock-out mice. Together, these findings indicate that AZI2 regulates bone mass by fine-tuning osteoclast survival. PMID:25691576

  4. Finely Tuned Asymmetric Platinum(IV) Anticancer Complexes: Structure-Activity Relationship and Application as Orally Available Prodrugs.

    PubMed

    Yap, Siew Qi; Chin, Chee Fei; Hong Thng, Agnes Hwee; Pang, Yi Yun; Ho, Han Kiat; Ang, Wee Han

    2017-02-20

    Platinum(IV) bis-carboxylates are highly versatile prodrug scaffolds with different axial ligands that can be functionalized while keeping the platinum(II) pharmacophore intact. Using a sequential acylation strategy, we developed a class of Pt(IV) prodrugs of cisplatin with contrasting lipophilic and hydrophilic ligands. We investigated their stability, reduction rates, lipophilicity, aqueous solubility, and antiproliferative efficacies, and assessed for correlations among the parameters that could be useful in drug design. We showed that compounds with high lipophilicity result in better antiproliferative effects in vitro and in vivo, with one of the three compounds tested showing better efficacy than satraplatin against an animal model of colorectal cancer, owing to its higher solubility and lower reduction rates. Our asymmetric Pt(IV) prodrugs may pave the way for a highly predictable, fine-tuned class of orally available Pt(IV) prodrugs for the treatment of colorectal cancer. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Evident Improvement of Electrochemical Water Oxidation by Fine Tuning the Structure of Tetradentate N4 Ligands of Molecular Copper Catalysts.

    PubMed

    Shen, Junyu; Wang, Mei; Gao, Jinsuo; Han, Hongxian; Liu, Hong; Sun, Licheng

    2017-09-03

    Two copper complexes, [L1Cu(OH2)](BF4)2 [1, L1 = N,N'-dimethyl-N,N'-bis(pyridin-2-ylmethyl)-1,2-diaminoethane] and [L2Cu(OH2)](BF4)2 [2, L2 = 2,7-bis(2-pyridyl)-3,6-diaza-2,6-octadiene], were prepared as molecular water oxidation catalysts. Complex 1 displayed an overpotential (η) of 1.07 V at 1 mA cm-2 and an observed rate constant (kobs) of 13.5 s-1 at η 1.0 V in pH 9.0 phosphate buffer solution, while 2 exhibited a significantly smaller η (0.70 V) to reach 1 mA cm-2 and a higher kobs (50.4 s-1) than 1 under identical test conditions. Additionally, 2 displayed a better stability than 1 in controlled potential electrolysis experiments in a Faradaic efficiency of 94% for O2 evolution at 1.58 V, when a casing tube was used for Pt cathode. The possible mechanism for 1- and 2-catalyzed O2 evolution reactions is discussed based on the experimental evidence. These comparative results indicate that fine tuning structures of tetradentate N4 ligands can bring about significant change in the performance of copper complexes for electrochemical water oxidation. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Fine Tuning of MOF-505 Analogues To Reduce Low-Pressure Methane Uptake and Enhance Methane Working Capacity.

    PubMed

    Zhang, Mingxing; Zhou, Wei; Pham, Tony; Forrest, Katherine A; Liu, Wenlong; He, Yabing; Wu, Hui; Yildirim, Taner; Chen, Banglin; Space, Brian; Pan, Yi; Zaworotko, Michael J; Bai, Junfeng

    2017-09-11

    We present a crystal engineering strategy to fine tune the pore chemistry and CH4 -storage performance of a family of isomorphic MOFs based upon PCN-14. These MOFs exhibit similar pore size, pore surface, and surface area (around 3000 m(2)  g(-1) ) and were prepared with the goal to enhance CH4 working capacity. [Cu2 (L2)(H2 O)2 ]n (NJU-Bai 41: NJU-Bai for Nanjing University Bai's group), [Cu2 (L3)(H2 O)2 ]n (NJU-Bai 42), and [Cu2 (L4)(DMF)2 ]n (NJU-Bai 43) were prepared and we observed that the CH4 volumetric working capacity and volumetric uptake values are influenced by subtle changes in structure and chemistry. In particular, the CH4 working capacity of NJU-Bai 43 reaches 198 cm(3) (STP: 273.15 K, 1 atm) cm(-3) at 298 K and 65 bar, which is amongst the highest reported for MOFs under these conditions and is much higher than the corresponding value for PCN-14 (157 cm(3) (STP) cm(-3) ). © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. A family of enantiopure Fe(III)4 single molecule magnets: fine tuning of energy barrier by remote substituent.

    PubMed

    Zhu, Yuan-Yuan; Cui, Chang; Qian, Kang; Yin, Ji; Wang, Bing-Wu; Wang, Zhe-Ming; Gao, Song

    2014-08-21

    A new family of enantiopure star-shaped Fe(III)4 single-molecule magnets (SMMs) with the general formula [Fe4(L(K))6] (H2L = (R or S)-2-((2-hydroxy-1-phenylethylimino methyl)phenol); K = H (), Cl (), Br (), I (), and t-Bu ()), were structurally and magnetically characterized. Complex was reported in our previous paper (Chem. Commun., 2011, 47, 8049-8051). Detailed magnetic measurements and a systematic magneto-structural correlation study revealed that the SMM properties of this series of compounds can be finely tuned by the remote substituent of the ligands. Although the change in the coordination environment of the central Fe(3+) ions is very small, the properties of SMM behavior are changed considerably. All five complexes display frequency dependence of the ac susceptibility. However, the χ peaks of complexes and cannot be observed down to 0.5 K. The fitted anisotropy energy barriers (Ueff) of complexes , , and were 5.9, 7.1, and 11.0 K, respectively. Moreover, the hysteresis loops of these three complexes can be also observed around 0.5 K. Magneto-structural correlation analyses revealed that the coordination symmetry of the central Fe(3+) ion and the intermolecular interaction are two key factors affecting the SMM properties. Deviation to a trigonal prism coordination environment and the existence of intermolecular interactions between neighboring clusters may both reduce the anisotropy energy barriers.

  8. Transcriptional control of flavonoid biosynthesis: fine-tuning of the MYB-bHLH-WD40 (MBW) complex.

    PubMed

    Li, Shutian

    2014-01-01

    Flavonoids are plant secondary polyphenolic metabolites and fulfil many vital biological functions, offering a valuable metabolic and genetic model for studying transcriptional control of gene expression. Arabidopsis thaliana mainly accumulates 3 types of flavonoids, including flavonols, anthocyanins, and proanthocyanidins (PAs). Flavonoid biosynthesis involves a multitude of well-characterized enzymatic and regulatory proteins. Three R2R3-MYB proteins (MYB11, MYB12, and MYB111) control flavonol biosynthesis via activating the early biosynthetic steps, whereas the production of anthocyanins and PAs requires the MYB-bHLH-WD40 (MBW) complex to activate the late biosynthetic genes. Additional regulators of flavonoid biosynthesis have recently come to light, which interact with R2R3-MYBs or bHLHs to organize or disrupt the formation of the MBW complex, leading to enhanced or compromised flavonoid production. This mini-review gives an overview of how these novel players modulate flavonoid metabolism and thus plant developmental processes and further proposes a fine-tuning mechanism to complete the complex regulatory network controlling flavonoid biosynthesis.

  9. Fine-tuning Structures from Molecules to Nanophases: Insight into the Origin of Superior Organic Photovoltaic Efficiency

    NASA Astrophysics Data System (ADS)

    Chen, Wei; Darling, Seth

    2012-02-01

    Organic photovoltaics (OPV) represent one of the most promising technologies for next-generation solar energy conversion due to their low-cost and scalability. To realize this potential, efficiencies must be improved for which a deeper understanding of the nanoscale morphology and molecular organization is required. Using the state-of-the-art PTB series of conjugated copolymers synthesized at the University of Chicago, we probed the internal structure of these materials both in solution and in films containing polymer/fullerene blends using a suite of tools spearheaded by neutron and x-ray scattering and, thereby, conceive the structural evolution from solution to thin films. Fine-tuning molecular structures via selective atomic replacement on the main chain of PTB copolymers, we gained unique insights into the structure-performance relationships, especially key features such as intermixing of polymers with fullerenes. Progress established in the course of these structural and morphological characterizations outline above will serve as the foundation for further improving the efficiency of polymer solar cells to realize their large-scale commercial use.

  10. miR-17-92 fine-tunes MYC expression and function to ensure optimal B cell lymphoma growth

    PubMed Central

    Mihailovich, Marija; Bremang, Michael; Spadotto, Valeria; Musiani, Daniele; Vitale, Elena; Varano, Gabriele; Zambelli, Federico; Mancuso, Francesco M.; Cairns, David A.; Pavesi, Giulio; Casola, Stefano; Bonaldi, Tiziana

    2015-01-01

    The synergism between c-MYC and miR-17-19b, a truncated version of the miR-17-92 cluster, is well-documented during tumor initiation. However, little is known about miR-17-19b function in established cancers. Here we investigate the role of miR-17-19b in c-MYC-driven lymphomas by integrating SILAC-based quantitative proteomics, transcriptomics and 3′ untranslated region (UTR) analysis upon miR-17-19b overexpression. We identify over one hundred miR-17-19b targets, of which 40% are co-regulated by c-MYC. Downregulation of a new miR-17/20 target, checkpoint kinase 2 (Chek2), increases the recruitment of HuR to c-MYC transcripts, resulting in the inhibition of c-MYC translation and thus interfering with in vivo tumor growth. Hence, in established lymphomas, miR-17-19b fine-tunes c-MYC activity through a tight control of its function and expression, ultimately ensuring cancer cell homeostasis. Our data highlight the plasticity of miRNA function, reflecting changes in the mRNA landscape and 3′ UTR shortening at different stages of tumorigenesis. PMID:26555894

  11. Activation of oxygen-mediating pathway using copper ions: fine-tuning of growth kinetics in gold nanorod overgrowth.

    PubMed

    Liu, Wenqi; Zhang, Hui; Wen, Tao; Yan, Jiao; Hou, Shuai; Shi, Xiaowei; Hu, Zhijian; Ji, Yinglu; Wu, Xiaochun

    2014-10-21

    Growth kinetics plays an important role in the shape control of nanocrystals (NCs). Herein, we presented a unique way to fine-tune the growth kinetics via oxidative etching activated by copper ions. For the overgrowth of gold nanorods (Au NRs), competitive adsorption of dissolved oxygen on rod surface was found to slow down the overgrowth rate. Copper ions were able to remove the adsorbed oxygen species from the Au surface via oxidative etching, thus exposing more reaction sites for Au deposition. In this way, copper ions facilitated the overgrowth process. Furthermore, Cu(2+) rather than Cu(+) acted as the catalyst for the oxidative etching. Comparative study with Ag(+) indicated that Cu(2+) cannot regulate NC shapes via an underpotential deposition mechanism. In contrast, Ag(+) led to the formation of Au tetrahexahedra (THH) and a slight decrease of the growth rate at similar growth conditions. Combining the distinct roles of the two ions enabled elongated THH to be produced. Copper ions activating the O2 pathway suggested that dissolved oxygen has a strong affinity for the Au surface. Moreover, the results of NC-sensitized singlet oxygen ((1)O2) indicated that the absorbed oxygen species on the surface of Au NCs bounded with low-index facets mainly existed in the form of molecular O2.

  12. Angiogenic sprouting requires the fine tuning of endothelial cell cohesion by the Raf-1/Rok-α complex.

    PubMed

    Wimmer, Reiner; Cseh, Botond; Maier, Barbara; Scherrer, Karina; Baccarini, Manuela

    2012-01-17

    Sprouting angiogenesis, crucial for the development of new blood vessels, is a prime example of collective migration in which endothelial cells migrate as a group joined via cadherin-containing adherens junctions (AJ). The actomyosin apparatus is connected to AJ and generates contractile forces, which, depending on their strength and duration, increase or decrease cell cohesion. Thus, appropriate spatiotemporal control of junctional myosin is critical, but the mechanisms underlying it are incompletely understood. We show that Raf-1 is an essential component of this regulatory network and that its ablation impairs endothelial cell cohesion, sprouting, and tumor-induced angiogenesis. Mechanistically, Raf-1 is recruited to VE-cadherin complexes by a mechanism involving the small G protein Rap1 and is required to bring the Rho effector Rok-α to nascent AJs. This Raf-1-mediated fine tuning of Rok-α signaling allows the activation of junctional myosin and the timely maturation of AJ essential for maintaining cell cohesion during sprouting angiogenesis. Copyright © 2012 Elsevier Inc. All rights reserved.

  13. Disulfide-activated protein kinase G Iα regulates cardiac diastolic relaxation and fine-tunes the Frank-Starling response.

    PubMed

    Scotcher, Jenna; Prysyazhna, Oleksandra; Boguslavskyi, Andrii; Kistamas, Kornel; Hadgraft, Natasha; Martin, Eva D; Worthington, Jenny; Rudyk, Olena; Rodriguez Cutillas, Pedro; Cuello, Friederike; Shattock, Michael J; Marber, Michael S; Conte, Maria R; Greenstein, Adam; Greensmith, David J; Venetucci, Luigi; Timms, John F; Eaton, Philip

    2016-10-26

    The Frank-Starling mechanism allows the amount of blood entering the heart from the veins to be precisely matched with the amount pumped out to the arterial circulation. As the heart fills with blood during diastole, the myocardium is stretched and oxidants are produced. Here we show that protein kinase G Iα (PKGIα) is oxidant-activated during stretch and this form of the kinase selectively phosphorylates cardiac phospholamban Ser16-a site important for diastolic relaxation. We find that hearts of Cys42Ser PKGIα knock-in (KI) mice, which are resistant to PKGIα oxidation, have diastolic dysfunction and a diminished ability to couple ventricular filling with cardiac output on a beat-to-beat basis. Intracellular calcium dynamics of ventricular myocytes isolated from KI hearts are altered in a manner consistent with impaired relaxation and contractile function. We conclude that oxidation of PKGIα during myocardial stretch is crucial for diastolic relaxation and fine-tunes the Frank-Starling response.

  14. The TORC1 effector kinase Npr1 fine tunes the inherent activity of the Mep2 ammonium transport protein.

    PubMed

    Boeckstaens, Mélanie; Llinares, Elisa; Van Vooren, Pascale; Marini, Anna Maria

    2014-01-01

    The TORC1 complex controls cell growth upon integrating nutritional signals including amino-acid availability. TORC1 notably adapts the plasma membrane protein content by regulating arrestin-mediated endocytosis of amino-acid transporters. Here we demonstrate that TORC1 further fine tunes the inherent activity of the ammonium transport protein, Mep2, a yeast homologue of mammalian Rhesus factors, independently of arrestin-mediated endocytosis. The TORC1 effector kinase Npr1 and the upstream TORC1 regulator Npr2 control Mep2 transport activity by phospho-silencing a carboxy-terminal autoinhibitory domain. Under poor nitrogen supply, Npr1 enables Mep2 S457 phosphorylation and thus ammonium transport activity. Supplementation of the preferred nitrogen source glutamine leads to Mep2 inactivation and instant S457 dephosphorylation via plasma membrane Psr1 and Psr2 redundant phosphatases. This study underscores that TORC1 also adjusts nutrient permeability to regulate cell growth in a fast and flexible response to environmental perturbation, establishing a hierarchy in the transporters to be degraded, inactivated or maintained active at the plasma membrane.

  15. A Negative Feedback Loop between PHYTOCHROME INTERACTING FACTORs and HECATE Proteins Fine-Tunes Photomorphogenesis in Arabidopsis

    PubMed Central

    Zhu, Ling; Bu, Qingyun; Shen, Hui; Dang, Jonathan

    2016-01-01

    The phytochrome interacting factors (PIFs), a small group of basic helix-loop-helix transcription factors, repress photomorphogenesis both in the dark and light. Light signals perceived by the phytochrome family of photoreceptors induce rapid degradation of PIFs to promote photomorphogenesis. Here, we show that HECATE (HEC) proteins, another small group of HLH proteins, antagonistically regulate PIFs to promote photomorphogenesis. HEC1 and HEC2 heterodimerize with PIF family members. PIF1, HEC1, and HEC2 genes are spatially and temporally coexpressed, and HEC2 is localized in the nucleus. hec1, hec2, and hec3 single mutants and the hec1 hec2 double mutant showed hyposensitivity to light-induced seed germination and accumulation of chlorophyll and carotenoids, hallmark processes oppositely regulated by PIF1. HEC2 inhibits PIF1 target gene expression by directly heterodimerizing with PIF1 and preventing DNA binding and transcriptional activation activity of PIF1. Conversely, PIFs directly activate the expression of HEC1 and HEC2 in the dark, and light reduces the expression of these HECs possibly by degrading PIFs. HEC2 is partially degraded in the dark through the ubiquitin/26S-proteasome pathway and is stabilized by light. HEC2 overexpression also reduces the light-induced degradation of PIF1. Taken together, these data suggest that PIFs and HECs constitute a negative feedback loop to fine-tune photomorphogenesis in Arabidopsis thaliana. PMID:27073231

  16. Large-Scale Phenomics Identifies Primary and Fine-Tuning Roles for CRKs in Responses Related to Oxidative Stress

    PubMed Central

    Rayapuram, Channabasavangowda; Idänheimo, Niina; Hunter, Kerri; Kimura, Sachie; Merilo, Ebe; Vaattovaara, Aleksia; Oracz, Krystyna; Kaufholdt, David; Pallon, Andres; Anggoro, Damar Tri; Glów, Dawid; Lowe, Jennifer; Zhou, Ji; Mohammadi, Omid; Puukko, Tuomas; Albert, Andreas; Lang, Hans; Ernst, Dieter; Kollist, Hannes; Brosché, Mikael; Durner, Jörg; Borst, Jan Willem; Collinge, David B.; Karpiński, Stanisław; Lyngkjær, Michael F.; Robatzek, Silke; Wrzaczek, Michael; Kangasjärvi, Jaakko

    2015-01-01

    Cysteine-rich receptor-like kinases (CRKs) are transmembrane proteins characterized by the presence of two domains of unknown function 26 (DUF26) in their ectodomain. The CRKs form one of the largest groups of receptor-like protein kinases in plants, but their biological functions have so far remained largely uncharacterized. We conducted a large-scale phenotyping approach of a nearly complete crk T-DNA insertion line collection showing that CRKs control important aspects of plant development and stress adaptation in response to biotic and abiotic stimuli in a non-redundant fashion. In particular, the analysis of reactive oxygen species (ROS)-related stress responses, such as regulation of the stomatal aperture, suggests that CRKs participate in ROS/redox signalling and sensing. CRKs play general and fine-tuning roles in the regulation of stomatal closure induced by microbial and abiotic cues. Despite their great number and high similarity, large-scale phenotyping identified specific functions in diverse processes for many CRKs and indicated that CRK2 and CRK5 play predominant roles in growth regulation and stress adaptation, respectively. As a whole, the CRKs contribute to specificity in ROS signalling. Individual CRKs control distinct responses in an antagonistic fashion suggesting future potential for using CRKs in genetic approaches to improve plant performance and stress tolerance. PMID:26197346

  17. Fnr (EtrA) acts as a fine-tuning regulator of anaerobic metabolism in Shewanella oneidensis MR-1

    SciTech Connect

    Cruz-Garza, Claribel; Murray, Alison E.; Rodrigues, Jorge L.M.; Gralnick, Jeffrey A.; McCue, Lee Ann; Romine, Margaret F.; Loffler, F. E.; Tiedje, James M.

    2011-03-30

    EtrA in Shewanella oneidensis MR-1, a model organism for study of adaptation to varied redox niches, shares 73.6% and 50.8% amino acid sequence identity with the oxygen-sensing regulators Fnr in E. coli and Anr in Pseudomonas aeruginosa, respectively; however, its regulatory role of anaerobic metabolism in Shewanella spp. is not well understood. The expression of the nap genes, nrfA, cymA and hcp was significantly reduced in etrA deletion mutant EtrA7-1; however, limited anaerobic growth and nitrate reduction occurred, suggesting that multiple regulators control nitrate reduction in this strain. Dimethyl sulfoxide (DMSO) and fumarate reductase gene expression was down regulated at least 2-fold and the EtrA7-1 mutant grew poorly with fumarate and dimethyl sulfoxide (DMSO), suggesting both respiratory pathways are under EtrA control. Transcript analysis further suggested a role of EtrA in prophage activation and down regulation of genes implicated in aerobic metabolism. In contrast to previous studies that attributed a minor regulatory role to EtrA in Shewanella spp., this study demonstrates that EtrA acts as a global transcriptional regulator and confers physiological advantages to strain MR-1 under certain growth conditions. In conjunction with other regulators, EtrA fine-tunes the expression of genes involved in anaerobic metabolism in S. oneidensis strain MR-1.

  18. Comparative phosphoproteome profiling reveals a function of the STN8 kinase in fine-tuning of cyclic electron flow (CEF)

    PubMed Central

    Reiland, Sonja; Finazzi, Giovanni; Endler, Anne; Willig, Adrian; Baerenfaller, Katja; Grossmann, Jonas; Gerrits, Bertran; Rutishauser, Dorothea; Gruissem, Wilhelm; Rochaix, Jean-David; Baginsky, Sacha

    2011-01-01

    Important aspects of photosynthetic electron transport efficiency in chloroplasts are controlled by protein phosphorylation. Two thylakoid-associated kinases, STN7 and STN8, have distinct roles in short- and long-term photosynthetic acclimation to changes in light quality and quantity. Although some substrates of STN7 and STN8 are known, the complexity of this regulatory kinase system implies that currently unknown substrates connect photosynthetic performance with the regulation of metabolic and regulatory functions. We performed an unbiased phosphoproteome-wide screen with Arabidopsis WT and stn8 mutant plants to identify unique STN8 targets. The phosphorylation status of STN7 was not affected in stn8, indicating that kinases other than STN8 phosphorylate STN7 under standard growth conditions. Among several putative STN8 substrates, PGRL1-A is of particular importance because of its possible role in the modulation of cyclic electron transfer. The STN8 phosphorylation site on PGRL1-A is absent in both monocotyledonous plants and algae. In dicots, spectroscopic measurements with Arabidopsis WT, stn7, stn8, and stn7/stn8 double-mutant plants indicate a STN8-mediated slowing down of the transition from cyclic to linear electron flow at the onset of illumination. This finding suggests a possible link between protein phosphorylation by STN8 and fine-tuning of cyclic electron flow during this critical step of photosynthesis, when the carbon assimilation is not commensurate to the electron flow capacity of the chloroplast. PMID:21768351

  19. Disulfide-activated protein kinase G Iα regulates cardiac diastolic relaxation and fine-tunes the Frank–Starling response

    PubMed Central

    Scotcher, Jenna; Prysyazhna, Oleksandra; Boguslavskyi, Andrii; Kistamas, Kornel; Hadgraft, Natasha; Martin, Eva D.; Worthington, Jenny; Rudyk, Olena; Rodriguez Cutillas, Pedro; Cuello, Friederike; Shattock, Michael J.; Marber, Michael S.; Conte, Maria R.; Greenstein, Adam; Greensmith, David J.; Venetucci, Luigi; Timms, John F.; Eaton, Philip

    2016-01-01

    The Frank–Starling mechanism allows the amount of blood entering the heart from the veins to be precisely matched with the amount pumped out to the arterial circulation. As the heart fills with blood during diastole, the myocardium is stretched and oxidants are produced. Here we show that protein kinase G Iα (PKGIα) is oxidant-activated during stretch and this form of the kinase selectively phosphorylates cardiac phospholamban Ser16—a site important for diastolic relaxation. We find that hearts of Cys42Ser PKGIα knock-in (KI) mice, which are resistant to PKGIα oxidation, have diastolic dysfunction and a diminished ability to couple ventricular filling with cardiac output on a beat-to-beat basis. Intracellular calcium dynamics of ventricular myocytes isolated from KI hearts are altered in a manner consistent with impaired relaxation and contractile function. We conclude that oxidation of PKGIα during myocardial stretch is crucial for diastolic relaxation and fine-tunes the Frank–Starling response. PMID:27782102

  20. Fine-tuning of DDES and IDDES formulations to the k-ω shear stress transport model

    NASA Astrophysics Data System (ADS)

    Gritskevich, M. S.; Garbaruk, A. V.; Menter, F. R.

    2013-06-01

    Modifications are proposed of two recently developed hybrid CFD (computational fluid dynamics) strategies, Delayed Detached Eddy Simulation (DDES), and DDES with Improved wall-modeling capability (IDDES). The modifications are aimed at fine-tuning of these approaches to the k-ω SST (shear stress transport) background RANS (Reynolds-averaged Navier-Stokes) model. The first one includes recalibrated empirical constants in the shielding function of the Spalart-Allmaras (SA) based DDES which are shown to be suboptimal (not providing a needed level of elimination of the Model Stress Depletion (MSD)) for the SST-based DDES model. For the SST-IDDES variant, in addition to that, a simplification of the original SA-based formulation is proposed, which does not cause any visible degradation of the model performance. Both modifications are extensively tested on a range of attached and separated flows (developed channel, backward-facing step, periodic hills, wall-mounted hump, and hydrofoil with trailing edge separation).

  1. Fine tuning of Rac1 and RhoA alters cuspal shapes by remolding the cellular geometry.

    PubMed

    Li, Liwen; Tang, Qinghuang; Nakamura, Takashi; Suh, Jun-Gyo; Ohshima, Hayato; Jung, Han-Sung

    2016-11-28

    The anatomic and functional combinations of cusps and lophs (ridges) define the tooth shape of rodent molars, which distinguishes species. The species-specific cusp patterns result from the spatiotemporal induction of enamel knots (EKs), which require precisely controlled cellular behavior to control the epithelial invagination. Despite the well-defined roles of EK in cusp patterning, the determinants of the ultimate cuspal shapes and involvement of epithelial cellular geometry are unknown. Using two typical tooth patterns, the lophodont in gerbils and the bunodont in mice, we showed that the cuspal shape is determined by the dental epithelium at the cap stage, whereas the cellular geometry in the inner dental epithelium (IDE) is correlated with the cuspal shape. Intriguingly, fine tuning Rac1 and RhoA interconvert cuspal shapes between two species by remolding the cellular geometry. Either inhibition of Rac1 or ectopic expression of RhoA could region-distinctively change the columnar shape of IDE cells in gerbils to drive invagination to produce cusps. Conversely, RhoA reduction in mice inhibited invagination and developed lophs. Furthermore, we found that Rac1 and RhoA modulate the choices of cuspal shape by coordinating adhesion junctions, actin distribution, and fibronectin localization to drive IDE invagination.

  2. The role of post-translational modifications in fine-tuning BLM helicase function during DNA repair

    PubMed Central

    Böhm, Stefanie; Bernstein, Kara Anne

    2014-01-01

    RecQ-like helicases are a highly conserved family of proteins which are critical for preserving genome integrity. Genome instability is considered a hallmark of cancer and mutations within three of the five human RECQ genes cause hereditary syndromes that are associated with cancer predisposition. The human RecQ-like helicase BLM has a central role in DNA damage signaling, repair, replication, and telomere maintenance. BLM and its budding yeast orthologue Sgs1 unwind double-stranded DNA intermediates. Intriguingly, BLM functions in both a pro- and anti-recombinogenic manner upon replicative damage, acting on similar substrates. Thus, BLM activity must be intricately controlled to prevent illegitimate recombination events that could have detrimental effects on genome integrity. In recent years it has become evident that post-translational modifications (PTMs) of BLM allow a fine-tuning of its function. To date, BLM phosphorylation, ubiquitination, and SUMOylation have been identified, in turn regulating its subcellular localization, protein-protein interactions, and protein stability. In this review, we will discuss the cellular context of when and how these different modifications of BLM occur. We will reflect on the current model of how PTMs control BLM function during DNA damage repair and compare this to what is known about post-translational regulation of the budding yeast orthologue Sgs1. Finally, we will provide an outlook towards future research, in particular to dissect the cross-talk between the individual PTMs on BLM. PMID:25150915

  3. Auto-Regulatory RNA Editing Fine-Tunes mRNA Re-Coding and Complex Behaviour in Drosophila

    PubMed Central

    Savva, Yiannis A.; Jepson, James E.C; Sahin, Asli; Sugden, Arthur U.; Dorsky, Jacquelyn S.; Alpert, Lauren; Lawrence, Charles; Reenan, Robert A.

    2014-01-01

    Auto-regulatory feedback loops are a common molecular strategy used to optimize protein function. In Drosophila many mRNAs involved in neuro-transmission are re-coded at the RNA level by the RNA editing enzyme dADAR, leading to the incorporation of amino acids that are not directly encoded by the genome. dADAR also re-codes its own transcript, but the consequences of this auto-regulation in vivo are unclear. Here we show that hard-wiring or abolishing endogenous dADAR auto-regulation dramatically remodels the landscape of re-coding events in a site-specific manner. These molecular phenotypes correlate with altered localization of dADAR within the nuclear compartment. Furthermore, auto-editing exhibits sexually dimorphic patterns of spatial regulation and can be modified by abiotic environmental factors. Finally, we demonstrate that modifying dAdar auto-editing affects adaptive complex behaviors. Our results reveal the in vivo relevance of auto-regulatory control over post-transcriptional mRNA re-coding events in fine-tuning brain function and organismal behavior. PMID:22531175

  4. Fine-Tuning Translation Kinetics Selection as the Driving Force of Codon Usage Bias in the Hepatitis A Virus Capsid

    PubMed Central

    Aragonès, Lluís; Guix, Susana; Ribes, Enric; Bosch, Albert; Pintó, Rosa M.

    2010-01-01

    Hepatitis A virus (HAV), the prototype of genus Hepatovirus, has several unique biological characteristics that distinguish it from other members of the Picornaviridae family. Among these, the need for an intact eIF4G factor for the initiation of translation results in an inability to shut down host protein synthesis by a mechanism similar to that of other picornaviruses. Consequently, HAV must inefficiently compete for the cellular translational machinery and this may explain its poor growth in cell culture. In this context of virus/cell competition, HAV has strategically adopted a naturally highly deoptimized codon usage with respect to that of its cellular host. With the aim to optimize its codon usage the virus was adapted to propagate in cells with impaired protein synthesis, in order to make tRNA pools more available for the virus. A significant loss of fitness was the immediate response to the adaptation process that was, however, later on recovered and more associated to a re-deoptimization rather than to an optimization of the codon usage specifically in the capsid coding region. These results exclude translation selection and instead suggest fine-tuning translation kinetics selection as the underlying mechanism of the codon usage bias in this specific genome region. Additionally, the results provide clear evidence of the Red Queen dynamics of evolution since the virus has very much evolved to re-adapt its codon usage to the environmental cellular changing conditions in order to recover the original fitness. PMID:20221432

  5. Control of Wnt5b secretion by Wntless modulates chondrogenic cell proliferation through fine-tuning fgf3 expression.

    PubMed

    Wu, Bo-Tsung; Wen, Shih-Hsien; Hwang, Sheng-Ping L; Huang, Chang-Jen; Kuan, Yung-Shu

    2015-06-15

    Wnts and Fgfs regulate various tissues development in vertebrates. However, how regional Wnt or Fgf activities are established and how they interact in any given developmental event is elusive. Here, we investigated the Wnt-mediated craniofacial cartilage development in zebrafish and found that fgf3 expression in the pharyngeal pouches is differentially reduced along the anteroposterior axis in wnt5b mutants and wntless (wls) morphants, but its expression is normal in wnt9a and wnt11 morphants. Introducing fgf3 mRNAs rescued the cartilage defects in Wnt5b- and Wls-deficient larvae. In wls morphants, endogenous Wls expression is not detectable but maternally deposited Wls is present in eggs, which might account for the lack of axis defects in wls morphants. Secretion of endogenous Wnt5b but not Wnt11 was affected in the pharyngeal tissue of Wls morphants, indicating that Wls is not involved in every Wnt secretion event. Furthermore, cell proliferation but not apoptosis in the developing jaw was affected in Wnt5b- and Wls-deficient embryos. Therefore, Wnt5b requires Wls for its secretion and regulates the proliferation of chondrogenic cells through fine-tuning the expression of fgf3 during jaw cartilage development.

  6. Fine tuning of Rac1 and RhoA alters cuspal shapes by remolding the cellular geometry

    PubMed Central

    Li, Liwen; Tang, Qinghuang; Nakamura, Takashi; Suh, Jun-Gyo; Ohshima, Hayato; Jung, Han-Sung

    2016-01-01

    The anatomic and functional combinations of cusps and lophs (ridges) define the tooth shape of rodent molars, which distinguishes species. The species-specific cusp patterns result from the spatiotemporal induction of enamel knots (EKs), which require precisely controlled cellular behavior to control the epithelial invagination. Despite the well-defined roles of EK in cusp patterning, the determinants of the ultimate cuspal shapes and involvement of epithelial cellular geometry are unknown. Using two typical tooth patterns, the lophodont in gerbils and the bunodont in mice, we showed that the cuspal shape is determined by the dental epithelium at the cap stage, whereas the cellular geometry in the inner dental epithelium (IDE) is correlated with the cuspal shape. Intriguingly, fine tuning Rac1 and RhoA interconvert cuspal shapes between two species by remolding the cellular geometry. Either inhibition of Rac1 or ectopic expression of RhoA could region-distinctively change the columnar shape of IDE cells in gerbils to drive invagination to produce cusps. Conversely, RhoA reduction in mice inhibited invagination and developed lophs. Furthermore, we found that Rac1 and RhoA modulate the choices of cuspal shape by coordinating adhesion junctions, actin distribution, and fibronectin localization to drive IDE invagination. PMID:27892530

  7. Fine-tuning the stimulation of MLL1 methyltransferase activity by a histone H3-based peptide mimetic

    SciTech Connect

    Avdic, Vanja; Zhang, Pamela; Lanouette, Sylvain; Voronova, Anastassia; Skerjanc, Ilona; Couture, Jean-Francois

    2011-08-24

    The SET1 family of methyltransferases carries out the bulk of histone H3 Lys-4 methylation in vivo. One of the common features of this family is the regulation of their methyltransferase activity by a tripartite complex composed of WDR5, RbBP5, and Ash2L. To selectively probe the role of the SET1 family of methyltransferases, we have developed a library of histone H3 peptide mimetics and report herein the characterization of an N{alpha} acetylated form of histone H3 peptide (N{alpha}H3). Binding and inhibition studies reveal that the addition of an acetyl moiety to the N terminus of histone H3 significantly enhances its binding to WDR5 and prevents the stimulation of MLL1 methyltransferase activity by the WDR5-RbBP5-Ash2L complex. The crystal structure of N{alpha}H3 in complex with WDR5 reveals that a high-affinity hydrophobic pocket accommodates the binding of the acetyl moiety. These results provide the structural basis to control WDR5-RbBP5-Ash2L-MLL1 activity and a tool to manipulate stem cell differentiation programs.-Avdic, V., Zhang, P., Lanouette, S., Voronova, A., Skerjanc, I., Couture, J.-F. Fine-tuning the stimulation of MLL1 methyltransferase activity by a histone H3-based peptide mimetic.

  8. Fine-tuning of Notch signaling sets the boundary of the organ of Corti and establishes sensory cell fates

    PubMed Central

    Basch, Martin L; Brown, Rogers M; Jen, Hsin-I; Semerci, Fatih; Depreux, Frederic; Edlund, Renée K; Zhang, Hongyuan; Norton, Christine R; Gridley, Thomas; Cole, Susan E; Doetzlhofer, Angelika; Maletic-Savatic, Mirjana; Segil, Neil; Groves, Andrew K

    2016-01-01

    The signals that induce the organ of Corti and define its boundaries in the cochlea are poorly understood. We show that two Notch modifiers, Lfng and Mfng, are transiently expressed precisely at the neural boundary of the organ of Corti. Cre-Lox fate mapping shows this region gives rise to inner hair cells and their associated inner phalangeal cells. Mutation of Lfng and Mfng disrupts this boundary, producing unexpected duplications of inner hair cells and inner phalangeal cells. This phenotype is mimicked by other mouse mutants or pharmacological treatments that lower but not abolish Notch signaling. However, strong disruption of Notch signaling causes a very different result, generating many ectopic hair cells at the expense of inner phalangeal cells. Our results show that Notch signaling is finely calibrated in the cochlea to produce precisely tuned levels of signaling that first set the boundary of the organ of Corti and later regulate hair cell development. DOI: http://dx.doi.org/10.7554/eLife.19921.001 PMID:27966429

  9. Tuning the wavelength of spoof plasmons by adjusting the impedance contrast in an array of penetrable inclusions

    NASA Astrophysics Data System (ADS)

    Cordero, M. L.; Maurel, A.; Mercier, J.-F.; Félix, S.; Barra, F.

    2015-08-01

    While spoof plasmons have been proposed in periodic arrays of sound-hard inclusions, we show that they also exist when inclusions are penetrable. Moreover, we show that their wavelength can be tuned by the impedance mismatch between the inclusion material and the surrounding medium, beyond the usual effect of filling fraction in the array. It is demonstrated that sound-soft materials increase the efficiency in the generation of sub-wavelength plasmons, with much lower wavelengths than sound-hard materials and than a homogeneous slab. An application to the generation of acoustic spoof plasmons by an ultra compact array of air/polydimethylsiloxane inclusions in water is proposed with plasmon wavelength tunable up to deep sub-wavelength scales.

  10. Multilayered membranes with tuned well arrays to be used as regenerative patches.

    PubMed

    Martins, Nádia I; Sousa, Maria P; Custódio, Catarina A; Pinto, Vânia C; Sousa, Paulo J; Minas, Graça; Cleymand, Franck; Mano, João F

    2017-07-15

    Membranes have been explored as patches in tissue repair and regeneration, most of them presenting a flat geometry or a patterned texture at the nano/micrometer scale. Herein, a new concept of a flexible membrane featuring well arrays forming pore-like environments to accommodate cell culture is proposed. The processing of such membranes using polysaccharides is based on the production of multilayers using the layer-by-layer methodology over a patterned PDMS substrate. The detached multilayered membrane exhibits a layer of open pores at one side and a total thickness of 38±2.2µm. The photolithography technology used to produce the molds allows obtaining wells on the final membranes with a tuned shape and micro-scale precision. The influence of post-processing procedures over chitosan/alginate films with 100 double layers, including crosslinking with genipin or fibronectin immobilization, on the adhesion and proliferation of human osteoblast-like cells is also investigated. The results suggest that the presence of patterned wells affects positively cell adhesion, morphology and proliferation. In particular, it is seen that cells colonized preferentially the well regions. The geometrical features with micro to sub-millimeter patterned wells, together with the nano-scale organization of the polymeric components along the thickness of the film will allow to engineer highly versatile multilayered membranes exhibiting a pore-like microstructure in just one of the sides, that could be adaptable in the regeneration of multiple tissues. Flexible multilayered membranes containing multiple micro-reservoirs are found as potential regenerative patches. Layer-by-layer (LbL) methodology over a featured PDMS substrate is used to produce patterned membranes, composed only by natural-based polymers, that can be easily detached from the PDMS substrate. The combination of nano-scale control of the polymeric organization along the thickness of the chitosan/alginate (CHT

  11. Tuning the self-assembly of surfactants by the confinement of carbon nanotube arrays: a cornucopia of lamellar phase variants.

    PubMed

    Li, Zhen; Wang, Pan; Ma, Yunyun; Zhang, Jun; Dai, Caili; Yan, Youguo; Liu, Bing

    2015-04-14

    Tuning the self-assembly of building blocks to obtain a kaleidoscope of nanostructures is very important and challenging for the preparation of advanced nanomaterials. Amphiphiles confined within carbon nanotube (CNT) arrays can self-assemble into complex structures that maintain the "bilayer" characteristic of a lamellar phase, we call them "lamellar phase variants (LPVs)". In this work, we carried out coarse-grained molecular dynamics (MD) studies to uncover novel LPVs. By varying the pattern of a CNT array, we obtained the "bilayer tube (BT) series", which contains circular, hexagonal, octagonal, and elliptical nanotubes. Furthermore, by introducing dislocation to CNT arrays, we obtained the "bilayer scroll (BS) series" that contains polymorphic nano-scrolls. These nanostructures are very novel and intriguing. To gain insights into the formation of LPVs, we studied the morphology evolution, which was demonstrated to be an unfamiliar "successive self-assembly process". These unusual self-assembling nanostructures and the formation process could provide clues for further studies on tuning the self-assembly of building blocks. The strategies developed in this work to obtain novel nanostructures are expected to facilitate the design and fabrication of nano-devices.

  12. Fine-tuning terminal solvent ligands to rationally enhance the energy barrier in dinuclear dysprosium single-molecule magnets.

    PubMed

    Zhang, Kun; Yuan, Chen; Guo, Fu-Sheng; Zhang, Yi-Quan; Wang, Yao-Yu

    2016-12-20

    In search of simple approaches to rationally enhance the energy barriers in polynuclear dysprosium single-molecule magnets, a new system containing two structurally closely related dinuclear dysprosium complexes, namely [Dy2(L)2(DBM)2(DMF)2] (1) and [Dy2(L)2(DBM)2(DMA)2]·2DMA (2) (HDBM = dibenzoylmethane, H2L = 2-hydroxy-N'-(2-hydroxy-3-methoxybenzylidene)benzohydrazide), is introduced and the structure-dependent magnetic properties are investigated. The two complexes display only slight variations in the coordination geometries of the Dy(iii) ion but display remarkably different magnetic behaviors. By replacing the DMF (dimethylformamide) ligand in complex 1 with DMA (dimethylacetamide) in 2 while retaining the same coordination atoms, we were able to create a 3-fold enhancement in the energy barrier, from 24 K for complex 1 to 77 K for complex 2. Complete-active-space self-consistent field (CASSCF) calculations revealed that the charge distribution surrounding the Dy(iii) centers in 1 and 2 is the key factor in determining the relaxation properties of the SMMs. The introduction of an electron-donating CH3 group in DMA to replace the hydrogen in DMF resulted in a larger average charge along the magnetic axes of complex 2 compared to complex 1, which resulted in a stronger easy-axis ligand field, thus increasing the energy difference between the ground and the first excited states of complex 2. This work presents a simple method to rationally enhance the energy barrier in polynuclear lanthanide SMMs through fine-tuning of the electrostatic potential of the atoms along the magnetic axis.

  13. Catecholamines as immunomodulators: a role for adrenoceptor-mediated mechanisms in fine tuning of T-cell development.

    PubMed

    Leposavić, Gordana; Pilipović, Ivan; Radojević, Katarina; Pesić, Vesna; Perisić, Milica; Kosec, Dusko

    2008-12-15

    In its simplest form, effective T cell-mediated immunity emanates from the expansion of specific T cells activated in response to antigen. In establishing and maintaining the peripheral T-cell pool, the thymus plays a critical role. It does so by providing a microenvironment within which T-cell precursors proliferate, differentiate and undergo selection processes to create a fully functional population of major histocompatibility complex restricted, self-tolerant T cells. The control of the thymic function involves intrathymic, as well as sympathetic nervous and endocrine system signalling. In addition to postganglionic noradrenergic fibres, both thymic lymphoid and non-lymphoid cells, including epithelial cells and macrophages, have been demonstrated to express tyrosine hydroxylase (TH), and suggested to form a local non-neural catecholaminergic cell network. A higher level of noradrenaline has been found in male than in female rat thymi, and a role of gonadal hormones in providing this dimorphism has been demonstrated. In addition, thymic lymphoid and non-lymphoid cells, including those expressing TH, have been found to bear beta- and alpha1-adrenoceptors (ARs) and a role of gonadal hormones in regulation of, at least, beta-AR density and signalling has been suggested. These findings have also entailed conclusion that catecholamines (CAs) influence T-cell development, not only via neurocrine/endocrine, but also via autocrine/paracrine action. Generally, CAs have been shown to exert an inhibitory influence on thymopoiesis. Role of alpha1- and beta-AR-mediated mechanisms in maintaining thymic homeostasis and in fine tuning of both conventional and regulatory T-cell development is discussed in the manuscript.

  14. Fine-Tuning of the Cpx Envelope Stress Response Is Required for Cell Wall Homeostasis in Escherichia coli

    PubMed Central

    Delhaye, Antoine; Collet, Jean-François

    2016-01-01

    ABSTRACT The envelope of Gram-negative bacteria is an essential compartment that constitutes a protective and permeability barrier between the cell and its environment. The envelope also hosts the cell wall, a mesh-like structure made of peptidoglycan (PG) that determines cell shape and provides osmotic protection. Since the PG must grow and divide in a cell-cycle-synchronized manner, its synthesis and remodeling are tightly regulated. Here, we discovered that PG homeostasis is intimately linked to the levels of activation of the Cpx system, an envelope stress response system traditionally viewed as being involved in protein quality control in the envelope. We first show that Cpx is activated when PG integrity is challenged and that this activation provides protection to cells exposed to antibiotics inhibiting PG synthesis. By rerouting the outer membrane lipoprotein NlpE, a known Cpx activator, to a different envelope subcompartment, we managed to manipulate Cpx activation levels. We found that Cpx overactivation leads to aberrant cellular morphologies, to an increased sensitivity to β-lactams, and to dramatic division and growth defects, consistent with a loss of PG homeostasis. Remarkably, these phenotypes were largely abrogated by the deletion of ldtD, a Cpx-induced gene involved in noncanonical PG cross-linkage, suggesting that this transpeptidase is an important link between PG homeostasis and the Cpx system. Altogether our data show that fine-tuning of an envelope quality control system constitutes an important layer of regulation of the highly organized cell wall structure. PMID:26908573

  15. The S1 Helix Critically Regulates the Finely-tuned Gating of Kv11.1 Channels.

    PubMed

    Phan, Kevin; Ng, Chai Ann; David, Erikka; Shishmarev, Dmitry; Kuchel, Philip W; Vandenberg, Jamie I; Perry, Matthew D

    2017-03-09

    Congenital mutations in the cardiac Kv11.1 channel can cause long QT syndrome type 2 (LQTS2), a heart rhythm disorder associated with sudden cardiac death. Mutations act either by reducing protein expression at the membrane, and/or by perturbing the intricate gating properties of Kv11.1 channels. A number of clinical LQTS2-associated mutations have been reported in the first transmembrane segment (S1) of Kv11.1 channels but the role of this region of the channel is largely unexplored. In part this is due to problems defining the extent of the S1 helix, as a consequence of its low sequence homology with other Kv family members. Here we used NMR spectroscopy and electrophysiological characterization to show that the S1 of Kv11.1 channels extends seven helical turns, from Pro405 to Phe431, and is flanked by unstructured loops. Functional analysis suggests that pre-S1 loop residues His402 and Tyr403 play an important role in regulating the kinetics and voltage dependence of channel activation and deactivation. Multiple residues within the S1 helix also play an important role in fine-tuning the voltage dependence of activation, regulating slow deactivation, and modulating C-type inactivation of Kv11.1 channels. Analyses of LQTS2-associated mutations in the pre-S1 loop or S1 helix of Kv11.1 channels demonstrate perturbations to both protein expression and most gating transitions. Thus S1 region mutations would reduce both the action potential repolarizing current passed by Kv11.1 channels in cardiac myocytes, as well as the current passed in response to premature depolarizations that normally helps protect against the formation of ectopic beats.

  16. Fine-tuning of Hh signaling by the RNA-binding protein Quaking to control muscle development.

    PubMed

    Lobbardi, Riadh; Lambert, Guillaume; Zhao, Jue; Geisler, Robert; Kim, Hyejeong R; Rosa, Frederic M

    2011-05-01

    The development of the different muscles within the somite is a complex process that involves the Hedgehog (Hh) signaling pathway. To specify the proper number of muscle cells and organize them spatially and temporally, the Hh signaling pathway needs to be precisely regulated at different levels, but only a few factors external to the pathway have been described. Here, we report for the first time the role of the STAR family RNA-binding protein Quaking A (QkA) in somite muscle development. We show in zebrafish that the loss of QkA function affects fast muscle fiber maturation as well as Hh-induced muscle derivative specification and/or morphogenesis. Mosaic analysis reveals that fast fiber maturation depends on the activity of QkA in the environment of fast fiber progenitors. We further show that Hh signaling requires QkA activity for muscle development. By an in silico approach, we screened the 3'UTRs of known Hh signaling component mRNAs for the Quaking response element and found the transcription factor Gli2a, a known regulator of muscle fate development. Using destabilized GFP as a reporter, we show that the gli2a mRNA 3'UTR is a functional QkA target. Consistent with this notion, the loss of QkA function rescued slow muscle fibers in yot mutant embryos, which express a dominant-negative Gli2a isoform. Thus, our results reveal a new mechanism to ensure muscle cell fate diversity by fine-tuning of the Hh signaling pathway via RNA-binding proteins.

  17. Fine-Tuning the Activity of Metal-Organic Framework-Supported Cobalt Catalysts for the Oxidative Dehydrogenation of Propane.

    PubMed

    Li, Zhanyong; Peters, Aaron W; Platero-Prats, Ana E; Liu, Jian; Kung, Chung-Wei; Noh, Hyunho; DeStefano, Matthew R; Schweitzer, Neil M; Chapman, Karena W; Hupp, Joseph T; Farha, Omar K

    2017-10-04

    Few-atom cobalt-oxide clusters, when dispersed on a Zr-based metal-organic framework (MOF) NU-1000, have been shown to be active for the oxidative dehydrogenation (ODH) of propane at low temperatures (< 230 °C), affording a selective and stable propene production catalyst. In our current work, a series of promoter ions with varying Lewis acidity, including Ni(II), Zn(II), Al(III), Ti(IV) and Mo(VI), are anchored as metal-oxide,hydroxide clusters to NU-1000 followed by Co(II) ion deposition, yielding a series of NU-1000-supported bimetallic-oxo,hydroxo,aqua clusters. Using difference envelope density (DED) analyses, the spatial locations of the promoter ions and catalytic cobalt ions are determined. For all samples the promoter ions are sited between pairs of Zr6 nodes along the MOF c axis whereas the location of the cobalt ions varies with the promoter ions. These NU-1000-supported bimetallic-oxide clusters are active for propane ODH after thermal activation under O2 to open a cobalt coordination site and to oxidize Co(II) to Co(III), as evidenced by operando X-ray absorption spectroscopy at the Co K-edge. In accord with the decreasing Lewis acidity of the promoter ion, catalytic activity increases in the order: Mo(VI)fine-tune the structure-dependent activity of MOF-supported heterogeneous catalysts. Coupled with mechanistic studies-computational or experimental-this ability may translate into informed prediction of improved catalysts for propane ODH and other chemical reactions.

  18. Fine-Tuning Motile Cilia and Flagella: Evolution of the Dynein Motor Proteins from Plants to Humans at High Resolution

    PubMed Central

    Kollmar, Martin

    2016-01-01

    The flagellum is a key innovation linked to eukaryogenesis. It provides motility by regulated cycles of bending and bend propagation, which are thought to be controlled by a complex arrangement of seven distinct dyneins in repeated patterns of outer- (OAD) and inner-arm dynein (IAD) complexes. Electron tomography showed high similarity of this axonemal repeat pattern across ciliates, algae, and animals, but the diversity of dynein sequences across the eukaryotes has not yet comprehensively been resolved and correlated with structural data. To shed light on the evolution of the axoneme I performed an exhaustive analysis of dyneins using the available sequenced genome data. Evidence from motor domain phylogeny allowed expanding the current set of nine dynein subtypes by eight additional isoforms with, however, restricted taxonomic distributions. I confirmed the presence of the nine dyneins in all eukaryotic super-groups indicating their origin predating the last eukaryotic common ancestor. The comparison of the N-terminal tail domains revealed a most likely axonemal dynein origin of the new classes, a group of chimeric dyneins in plants/algae and Stramenopiles, and the unique domain architecture and origin of the outermost OADs present in green algae and ciliates but not animals. The correlation of sequence and structural data suggests the single-headed class-8 and class-9 dyneins to localize to the distal end of the axonemal repeat and the class-7 dyneins filling the region up to the proximal heterodimeric IAD. Tracing dynein gene duplications across the eukaryotes indicated ongoing diversification and fine-tuning of flagellar functions in extant taxa and species. PMID:27880711

  19. Fine-tune optical absorption and light emitting behavior of the CdS/PVA hybridized film nanocomposite

    NASA Astrophysics Data System (ADS)

    Heiba, Z. K.; Mohamed, Mohamed Bakr; Imam, N. G.

    2017-05-01

    CdS nanoparticles (NPs) nucleated at different temperatures were composited with PVA to control and fine-tune optical absorption and emission of the nano-hybrid composite by varying the sizes of the CdS NPs which in turn depends on the nucleation temperature. The implanting of CdS NPs into PVA matrix was confirmed by XRD hand in hand with absorption and photoluminescence spectroscopic techniques. UV/VIS absorption spectra confirm the formation of hybridized film CdS/PVA nanocomposite with refractive index in the range of 2-4. UV/VIS measurements were also used in calculating different optical and dielectric parameters such as refractive index, extinction coefficient, dielectric constants, and optical conductivity. The optical parameters varied with the incorporation of CdS NPs within PVA matrix; accordingly, the optical constants of the nanocomposite films could be controlled by size of CdS content. Tauc's relation was used to determine the optical band gap and to determine the type of electronic transition. It is found that the direct allowed transition is more probable in CdS/PVA nanocomposite film of direct band gap around 3.8 eV. Blue and green light emissions from CdS/PVA nanocomposite film have been observed. Further, the PL studies indicated the emission peak observed at UV band represents band to band transition, while the blue and green emissions could be assigned to the optical transition of the first excitonic state of the CdS NPs and emission from interstitial sulfur respectively. The blue shift in the PL spectra was parallel to the shift observed in UV/VIS spectra. Because of its excellent fluorescence and highly transparent performance, the composite film of CdS nucleated at 200 °C was found to be suitable for bio-related applications such as bio-labeling, bio-imaging, drug delivery, and LEDs as well as a window layer in solar cell.

  20. Metabolic control of respiratory levels in coenzyme Q biosynthesis-deficient Escherichia coli strains leading to fine-tune aerobic lactate fermentation.

    PubMed

    Wu, Hui; Bennett, George N; San, Ka-Yiu

    2015-08-01

    A novel strategy to finely control the electron transfer chain (ETC) activity of Escherichia coli was established. In this study, the fine-tuning of the ubiquinone biosynthesis pathway was applied to further controlling ETC function in coenzyme Q8 biosynthesis-deficient E. coli strains, HW108 and HW109, which contain mutations in ubiE and ubiG, respectively. A competing pathway on the intermediate substrates of the Q8 synthesis pathway, catalyzed by diphosphate:4-hydroxybenzoate geranyltransferase (PGT-1) of Lithospermum erythrorhizon, was introduced into these mutant strains. A nearly theoretical yield of lactate production can be achieved under fully aerobic conditions via an in vivo, genetically fine-tunable means to further control the activity of the ETC of the Q8 biosynthesis-deficient E. coli strains.

  1. Listeria monocytogenes 10403S Arginine Repressor ArgR Finely Tunes Arginine Metabolism Regulation under Acidic Conditions

    PubMed Central

    Cheng, Changyong; Dong, Zhimei; Han, Xiao; Sun, Jing; Wang, Hang; Jiang, Li; Yang, Yongchun; Ma, Tiantian; Chen, Zhongwei; Yu, Jing; Fang, Weihuan; Song, Houhui

    2017-01-01

    Listeria monocytogenes is able to colonize human and animal intestinal tracts and to subsequently cross the intestinal barrier, causing systemic infection. For successful establishment of infection, L. monocytogenes must survive the low pH environment of the stomach. L. monocytogenes encodes a functional ArgR, a transcriptional regulator belonging to the ArgR/AhrC arginine repressor family. We aimed at clarifying the specific functions of ArgR in arginine metabolism regulation, and more importantly, in acid tolerance of L. monocytogenes. We showed that ArgR in the presence of 10 mM arginine represses transcription and expression of the argGH and argCJBDF operons, indicating that L. monocytogenes ArgR plays the classical role of ArgR/AhrC family proteins in feedback inhibition of the arginine biosynthetic pathway. Notably, transcription and expression of arcA (encoding arginine deiminase) and sigB (encoding an alternative sigma factor B) were also markedly repressed by ArgR when bacteria were exposed to pH 5.5 in the absence of arginine. However, addition of arginine enabled ArgR to derepress the transcription and expression of these two genes. Electrophoretic mobility shift assays showed that ArgR binds to the putative ARG boxes in the promoter regions of argC, argG, arcA, and sigB. Reporter gene analysis with gfp under control of the argG promoter demonstrated that ArgR was able to activate the argG promoter. Unexpectedly, deletion of argR significantly increased bacterial survival in BHI medium adjusted to pH 3.5 with lactic acid. We conclude that this phenomenon is due to activation of arcA and sigB. Collectively, our results show that L. monocytogenes ArgR finely tunes arginine metabolism through negative transcriptional regulation of the arginine biosynthetic operons and of the catabolic arcA gene in an arginine-independent manner during lactic acid-induced acid stress. ArgR also appears to activate catabolism as well as sigB transcription by anti

  2. Improving putrescine production by Corynebacterium glutamicum by fine-tuning ornithine transcarbamoylase activity using a plasmid addiction system.

    PubMed

    Schneider, Jens; Eberhardt, Dorit; Wendisch, Volker F

    2012-07-01

    Corynebacterium glutamicum shows a great potential for the production of the polyamide monomer putrescine (1,4-diaminobutane). Previously, we constructed the putrescine-producing strain PUT1 by deletion of argF, the gene for ornithine transcarbamoylase (OTC), and argR, encoding the L-arginine repressor, combined with heterologous expression of the Escherichia coli gene for L-ornithine decarboxylase SpeC. As a consequence of argF deletion, this strain requires supplementation of L-arginine and shows growth-decoupled putrescine production. To avoid costly supplementation with L-arginine and the strong feedback inhibition of the key enzyme N-acetylglutamate kinase (ArgB) by L-arginine, a plasmid addiction system for low-level argF expression was developed. By fine-tuning argF expression through modifications of the promoter, the translational start codon and/or the ribosome binding site, high productivity and titer could be obtained. OTC activity varied almost thousandfold between 960 and 1 mU mg⁻¹ resulting in putrescine yields on glucose from less than 0.001 up to 0.26 g g⁻¹, the highest yield in bacteria reported to date. The most promising strain, designated PUT21, was characterized comprehensively. PUT21 strain grew with a rate of 0.19 h⁻¹ in mineral salt medium without the need for L-arginine supplementation and produced putrescine with a yield of 0.16 g g⁻¹ glucose at a volumetric productivity of 0.57 g L⁻¹ h⁻¹ and a specific productivity of 0.042 g g⁻¹ h⁻¹. The carbon balance suggested that no major unidentified by-product was produced. Compared to the first-generation strain PUT1, the putrescine yield observed with PUT21 was increased by 60%. In fed-batch cultivation with C. glutamicum PUT21, a putrescine titer of 19 g L⁻¹ at a volumetric productivity of 0.55 g L⁻¹ h⁻¹ and a yield of 0.16 g g⁻¹ glucose could be achieved. Moreover, while plasmid segregation of the initial strain required antibiotic selection

  3. Organization of Vagal Afferents in Pylorus: Mechanoreceptors Arrayed for High Sensitivity and Fine Spatial Resolution?

    PubMed Central

    Powley, Terry L.; Hudson, Cherie N.; McAdams, Jennifer L.; Baronowsky, Elizabeth A.; Martin, Felecia N.; Mason, Jacqueline K.; Phillips, Robert J.

    2014-01-01

    The pylorus is innervated by vagal mechanoreceptors that project to gastrointestinal smooth muscle, but the distributions and specializations of vagal endings in the sphincter have not been fully characterized. To evaluate their organization, the neural tracer dextran biotin was injected into the nodose ganglia of rats. Following tracer transport, animals were perfused, and their pylori and antra were prepared as whole mounts. Specimens were processed to permanently label the tracer, and subsets were counterstained with Cuprolinic blue or immunostained for c-Kit. Intramuscular arrays (IMAs) in the circular muscle comprised the principal vagal afferent innervation of the sphincter. These pyloric ring IMAs were densely distributed and evidenced a variety of structural specializations. Morphometric comparisons between the arbors innervating the pylorus and a corresponding sample of IMAs in the adjacent antral circular muscle highlighted that sphincter IMAs branched profusely, forming more than twice as many branches as did antral IMAs (means of 405 vs. 165, respectively), and condensed their numerous neurites into compact receptive fields (~48% of the area of antral IMAs) deep in the circular muscle (~6 μm above the submucosa). Separate arbors of IMAs in the sphincter interdigitated and overlapped to form a 360° band of mechanoreceptors encircling the pyloric canal. The annulus of vagal IMA arbors, putative stretch receptors tightly intercalated in the sphincter ring and situated near the lumen of the pyloric canal, creates an architecture with the potential to generate gut reflexes on the basis of pyloric sensory maps of high sensitivity and fine spatial resolution. PMID:24656895

  4. Vapor-melt Ratio in Laser Fine Cutting of Slot Arrays

    NASA Astrophysics Data System (ADS)

    Xuyue, Wang; Qingxuan, Meng; Renke, Kang; Wenji, Xu; Dongming, Guo; Lianji, Wang

    2011-05-01

    In order to improve cut quality for slot arrays, a new method of laser fine cutting under the consideration of the ratio of vapor to melt is presented. Laser cutting of 6063 aluminum alloy sheet, 0.5 mm in thickness, was carried out on a JK701H Nd:YAG pulse laser cutting system. The effects of vapor-melt ratio on kerf width, surface roughness and recast layer were studied which relate cutting qualities. Observation on the cut samples with different vapor-melt ratios (0.687, 1.574, 3.601 varied with laser power increasing, and 1.535, 3.601, 7.661 with decreasing of beam cutting speed) shows that high vapor-melt ratio improves laser cut quality clearly. Kerf width 0.2 mm of smooth area on kerf top area and thickness 2.03 μm of recast layer are obtained. No dross was found on the kerf bottom and the percentage of the smooth area is up to 40% out of whole kerf side. The research on vapor-melt ratio provides a deeper understanding of laser cutting and improves laser cut quality effectively.

  5. Quantum Cascade Laser Tuning by Digital Micromirror Array-controlled External Cavity

    DTIC Science & Technology

    2014-01-01

    DISTRIBUTION/AVAILABILITY STATEMENT Approved for public release; distribution unlimited 13. SUPPLEMENTARY NOTES 14. ABSTRACT A quantum cascade laser ( QCL ...modulation (~30kHz modulation rate), and stable wavelength locking of the laser output. With one or more QCL gain elements built into the cavity, it...Proving Ground, MD 21010-5424 ABSTRACT A quantum cascade laser ( QCL ) tuning mechanism based on an external laser cavity containing a Micro

  6. Capability for Fine Tuning of the Refractive Index Sensing Properties of Long-Period Gratings by Atomic Layer Deposited Al2O3 Overlays

    PubMed Central

    Śmietana, Mateusz; Myśliwiec, Marcin; Mikulic, Predrag; Witkowski, Bartłomiej S.; Bock, Wojtek J.

    2013-01-01

    This work presents an application of thin aluminum oxide (Al2O3) films obtained using atomic layer deposition (ALD) for fine tuning the spectral response and refractive-index (RI) sensitivity of long-period gratings (LPGs) induced in optical fibers. The technique allows for an efficient and well controlled deposition at monolayer level (resolution ∼ 0.12 nm) of excellent quality nano-films as required for optical sensors. The effect of Al2O3 deposition on the spectral properties of the LPGs is demonstrated experimentally and numerically. We correlated both the increase in Al2O3 thickness and changes in optical properties of the film with the shift of the LPG resonance wavelength and proved that similar films are deposited on fibers and oxidized silicon reference samples in the same process run. Since the thin overlay effectively changes the distribution of the cladding modes and thus also tunes the device's RI sensitivity, the tuning can be simply realized by varying number of cycles, which is proportional to thickness of the high-refractive-index (n > 1.6 in infrared spectral range) Al2O3 film. The advantage of this approach is the precision in determining the film properties resulting in RI sensitivity of the LPGs. To the best of our knowledge, this is the first time that an ultra-precise method for overlay deposition has been applied on LPGs for RI tuning purposes and the results have been compared with numerical simulations based on LP mode approximation.

  7. Fine tuning of the quantum criticality in the heavy fermion superlattices CeRhIn5/YbRhIn5

    NASA Astrophysics Data System (ADS)

    Endo, Ryota; Toda, Rintaro; Hanaoka, Yousuke; Shimozawa, Masaaki; Yamashita, Takuya; Shimoyama, Yusuke; Kasahara, Shigeru; Tokiwa, Yoshi; Kasahara, Yuiti; Shibauchi, Takasada; Terashima, Takahito; Matsuda, Yuji

    2015-03-01

    Bulk CeRhIn5 shows an antiferromagnetic order at TN = 3.8 K. Using molecular beam epitaxy, we fabricate artificial superlattices CeRhIn5 (m) /YbRhIn5(7) (m = 2, 3, 4, 5, 9) containing m layers of CeRhIn5 alternating with seven layers of the nonmagnetic metal YbRhIn5. With decreasing m, TN is seriously reduced and nearly vanishes at the m = 3, indicating the dimensional tuning of the quantum criticality. When the magnetic field is applied to m = 3 superlattice perpendicular to the plane, T-linear resistivity, a hallmark of non-Fermi liquid, persists down to 50 mK, demonstrating the fine tuning of the quantum critical point

  8. Gate-tuned negative differential resistance observed at room temperature in an array of gold nanoparticles

    NASA Astrophysics Data System (ADS)

    Huong, Tran Thi Thu; Matsumoto, Kazuhiko; Moriya, Masataka; Shimada, Hiroshi; Kimura, Yasuo; Hirano-Iwata, Ayumi; Mizugaki, Yoshinao

    2017-04-01

    We fabricated a single-electron (SE) device using gold nanoparticles (Au NPs). Drain, source, and gate electrodes on a SiO{_2}/Si substrate were formed using electron beam lithography (EBL) and thermal evaporation of Au. Subsequently, solutions of 3-nm-diameter and 5-nm-diameter Au NPs were dropped on the device to make current paths through Au NPs among the electrodes. Measurements of the device exhibited negative differential resistance (NDR) in the current-voltage characteristics between the drain and source electrodes at room temperature (298 K). The NDR behavior was tuned by applying a gate voltage.

  9. Detection of Regional Infrasound Signals Using Array Data - Testing, Tuning, and Physical Interpretation

    NASA Astrophysics Data System (ADS)

    Park, J.; Stump, B. W.; Hayward, C.; Arrowsmith, S.; Che, I. Y.; Drob, D. P.

    2015-12-01

    In order to understand the impact environmental conditions have on infrasound detection, an automated detector that accounts for both correlated and uncorrelated noise is run on data from a number of infrasonic arrays, all in a regional context. Data from six seismo-acoustic arrays in South Korea (BRDAR, CHNAR, KMPAR, KSGAR, TJIAR, and YPDAR), which are cooperatively operated by Korea Institute of Geoscience and Mineral Resources (KIGAM) and Southern Methodist University (SMU), were used. An adaptive F-detector (AFD) (Arrowsmith et al., 2009) is applied that utilizes the F-statistic (Blandford, 1974) with an adaptive procedure that assesses variations in coherent noise in order to reduce false alarms. The adaptive procedure is characterized by the time dependent C-value that is found to depend on the weather conditions and local site effects. Arrays located on islands or near the coast produce noise power densities that are higher, consistent with both higher wind speeds as well as ocean wave contributions that vary seasonally. These results suggest that optimal detection processing requires careful characterization of background noise level and its relationship to enviornmental measures at individual arrays. This study also documents significant seasonal variations in infrasound detections including daily time of occurrence, total number of detections, and phase velocity/azimuth estimates. These time-dependent effects in most part explained by atmospheric models across the Korean peninsula as described by Drob et al. (2003).

  10. Experimental Profiling of a Non-truncated Focused Gaussian Beam and Fine-tuning of the Quadratic Phase in the Fresnel Gaussian Shape Invariant

    SciTech Connect

    S., Juan Manuel Franco; Cywiak, Moises; Cywiak, David; Mourad, Idir

    2015-06-24

    A homodyne profiler is used for recording the intensity distribution of focused non-truncated Gaussian beams. The spatial distributions are obtained at planes in the vicinity of the back-focal plane of a focusing lens placed at different distances from a He–Ne laser beam with a Gaussian intensity profile. Comparisons of the experimental data with those obtained from the analytical equations for an ideal focusing lens allow us to propose formulae to fine-tune the quadratic term in the Fresnel Gaussian shape invariant at each interface of the propagated field. Furthermore, we give analytical expressions to calculate adequately the propagation of the field through an optical system.

  11. Fine-tuning problems in quantum field theory and Lorentz invariance: A scalar-fermion model with a physical momentum cutoff

    NASA Astrophysics Data System (ADS)

    Cortés, J. L.; López-Sarrión, Justo

    2017-05-01

    In this paper, we study the consistency of having Lorentz invariance as a low energy approximation within the quantum field theory framework. A model with a scalar and a fermion field is used to show how a Lorentz invariance violating high momentum scale, a physical cutoff rendering the quantum field theory finite, can be made compatible with a suppression of Lorentz invariance violations at low momenta. The fine tuning required to get this suppression and to have a light scalar particle in the spectrum are determined at one loop.

  12. Tuning of Automatic Signal Detection Algorithms for IMS Style Infrasound Arrays

    DTIC Science & Technology

    2000-09-01

    Virginia. The synthetic signals were implanted into conventional array channel data using an implant strategy that allowed the signal to noise ratio ( SNR ...of the signal to be specified in a fashion that accounts for the spectral composition of the background. SNR values ranging from 0.01 to 100 were used...of Signal to Noise Ratio ( SNR ). RESEARCH ACCOMPLISHED In meeting this objective it was determined that the following steps constitute a workable

  13. Tuning the crystallinity of thermoelectric Bi2Te3 nanowire arrays grown by pulsed electrodeposition

    NASA Astrophysics Data System (ADS)

    Lee, Jongmin; Farhangfar, Shadyar; Lee, Jaeyoung; Cagnon, Laurent; Scholz, Roland; Gösele, Ulrich; Nielsch, Kornelius

    2008-09-01

    Arrays of thermoelectric bismuth telluride (Bi2Te3) nanowires were grown into porous anodic alumina (PAA) membranes prepared by a two-step anodization. Bi2Te3 nanowire arrays were deposited by galvanostatic, potentiostatic and pulsed electrodeposition from aqueous solution at room temperature. Depending on the electrodeposition method and as a consequence of different growth mechanisms, Bi2Te3 nanowires exhibit different types of crystalline microstructure. Bi2Te3 nanowire arrays, especially those grown by pulsed electrodeposition, have a highly oriented crystalline structure and were grown uniformly as compared to those grown by other electrodeposition techniques used. X-ray diffraction (XRD) analyses are indicative of the existence of a preferred growth orientation. High resolution transmission electron microscopy (HRTEM) and selected area electron diffraction (SAED) confirm the formation of a preferred orientation and highly crystalline structure of the grown nanowires. The nanowires were further analyzed by scanning electron microscopy (SEM). Energy dispersive x-ray spectrometry (EDX) indicates that the composition of Bi-Te nanowires can be controlled by the electrodeposition method and the relaxation time in the pulsed electrodeposition approach. The samples fabricated by pulsed electrodeposition were electrically characterized within the temperature range 240 K<=T<=470 K. Below T≈440 K, the nanowire arrays exhibited a semiconducting behavior. Depending on the relaxation time in the pulsed electrodeposition, the semiconductor energy gaps were estimated to be 210-290 meV. At higher temperatures, as a consequence of the enhanced carrier-phonon scattering, the measured electrical resistances increased slightly. The Seebeck coefficient was measured for every Bi2Te3 sample at room temperature by a very simple method. All samples showed a positive value (12-33 µV K-1), indicating a p-type semiconductor behavior.

  14. Detection of regional infrasound signals using array data: Testing, tuning, and physical interpretation.

    PubMed

    Park, Junghyun; Stump, Brian W; Hayward, Chris; Arrowsmith, Stephen J; Che, Il-Young; Drob, Douglas P

    2016-07-01

    This work quantifies the physical characteristics of infrasound signal and noise, assesses their temporal variations, and determines the degree to which these effects can be predicted by time-varying atmospheric models to estimate array and network performance. An automated detector that accounts for both correlated and uncorrelated noise is applied to infrasound data from three seismo-acoustic arrays in South Korea (BRDAR, CHNAR, and KSGAR), cooperatively operated by Korea Institute of Geoscience and Mineral Resources (KIGAM) and Southern Methodist University (SMU). Arrays located on an island and near the coast have higher noise power, consistent with both higher wind speeds and seasonably variable ocean wave contributions. On the basis of the adaptive F-detector quantification of time variable environmental effects, the time-dependent scaling variable is shown to be dependent on both weather conditions and local site effects. Significant seasonal variations in infrasound detections including daily time of occurrence, detection numbers, and phase velocity/azimuth estimates are documented. These time-dependent effects are strongly correlated with atmospheric winds and temperatures and are predicted by available atmospheric specifications. This suggests that commonly available atmospheric specifications can be used to predict both station and network detection performance, and an appropriate forward model improves location capabilities as a function of time.

  15. Detection of regional infrasound signals using array data: Testing, tuning, and physical interpretation

    DOE PAGES

    Park, Junghyun; Stump, Brian W.; Hayward, Chris; ...

    2016-07-14

    This work quantifies the physical characteristics of infrasound signal and noise, assesses their temporal variations, and determines the degree to which these effects can be predicted by time-varying atmospheric models to estimate array and network performance. An automated detector that accounts for both correlated and uncorrelated noise is applied to infrasound data from three seismo-acoustic arrays in South Korea (BRDAR, CHNAR, and KSGAR), cooperatively operated by Korea Institute of Geoscience and Mineral Resources (KIGAM) and Southern Methodist University (SMU). Arrays located on an island and near the coast have higher noise power, consistent with both higher wind speeds and seasonablymore » variable ocean wave contributions. On the basis of the adaptive F-detector quantification of time variable environmental effects, the time-dependent scaling variable is shown to be dependent on both weather conditions and local site effects. Significant seasonal variations in infrasound detections including daily time of occurrence, detection numbers, and phase velocity/azimuth estimates are documented. These time-dependent effects are strongly correlated with atmospheric winds and temperatures and are predicted by available atmospheric specifications. As a result, this suggests that commonly available atmospheric specifications can be used to predict both station and network detection performance, and an appropriate forward model improves location capabilities as a function of time.« less

  16. Detection of regional infrasound signals using array data: Testing, tuning, and physical interpretation

    SciTech Connect

    Park, Junghyun; Stump, Brian W.; Hayward, Chris; Arrowsmith, Stephen J.; Che, Il-Young; Drob, Douglas P.

    2016-07-14

    This work quantifies the physical characteristics of infrasound signal and noise, assesses their temporal variations, and determines the degree to which these effects can be predicted by time-varying atmospheric models to estimate array and network performance. An automated detector that accounts for both correlated and uncorrelated noise is applied to infrasound data from three seismo-acoustic arrays in South Korea (BRDAR, CHNAR, and KSGAR), cooperatively operated by Korea Institute of Geoscience and Mineral Resources (KIGAM) and Southern Methodist University (SMU). Arrays located on an island and near the coast have higher noise power, consistent with both higher wind speeds and seasonably variable ocean wave contributions. On the basis of the adaptive F-detector quantification of time variable environmental effects, the time-dependent scaling variable is shown to be dependent on both weather conditions and local site effects. Significant seasonal variations in infrasound detections including daily time of occurrence, detection numbers, and phase velocity/azimuth estimates are documented. These time-dependent effects are strongly correlated with atmospheric winds and temperatures and are predicted by available atmospheric specifications. As a result, this suggests that commonly available atmospheric specifications can be used to predict both station and network detection performance, and an appropriate forward model improves location capabilities as a function of time.

  17. Detection of regional infrasound signals using array data: Testing, tuning, and physical interpretation

    SciTech Connect

    Park, Junghyun; Stump, Brian W.; Hayward, Chris; Arrowsmith, Stephen J.; Che, Il-Young; Drob, Douglas P.

    2016-07-14

    This work quantifies the physical characteristics of infrasound signal and noise, assesses their temporal variations, and determines the degree to which these effects can be predicted by time-varying atmospheric models to estimate array and network performance. An automated detector that accounts for both correlated and uncorrelated noise is applied to infrasound data from three seismo-acoustic arrays in South Korea (BRDAR, CHNAR, and KSGAR), cooperatively operated by Korea Institute of Geoscience and Mineral Resources (KIGAM) and Southern Methodist University (SMU). Arrays located on an island and near the coast have higher noise power, consistent with both higher wind speeds and seasonably variable ocean wave contributions. On the basis of the adaptive F-detector quantification of time variable environmental effects, the time-dependent scaling variable is shown to be dependent on both weather conditions and local site effects. Significant seasonal variations in infrasound detections including daily time of occurrence, detection numbers, and phase velocity/azimuth estimates are documented. These time-dependent effects are strongly correlated with atmospheric winds and temperatures and are predicted by available atmospheric specifications. As a result, this suggests that commonly available atmospheric specifications can be used to predict both station and network detection performance, and an appropriate forward model improves location capabilities as a function of time.

  18. Facile Access to Twisted Intramolecular Charge-Transfer Fluorogens Bearing Highly Pretwisted Donor-Acceptor Systems Together with Readily Fine-Tuned Charge-Transfer Characters.

    PubMed

    Luo, Yanju; Wang, Yan; Chen, Shiqi; Wang, Ning; Qi, Yige; Zhang, Xiaogen; Yang, Minghui; Huang, Yan; Li, Ming; Yu, Junsheng; Luo, Daibing; Lu, Zhiyun

    2017-05-01

    Twisted intramolecular charge-transfer (TICT) fluorogens bearing highly pretwisted geometries and readily-fine-tuned charge-transfer characters are quite promising sensor and electroluminescence (EL) materials. In this study, by using 4-aryloxy-1,8-naphthalimide derivatives as the molecular framework, it is demonstrated for the first time that a CO bond could serve as the central bond to construct new TICT D-A systems. Photophysical and quantum chemical studies confirm that rotation around central CO bonds is responsible for the formation of a stable TICT state in these compounds. More importantly, owing to the structural adjustability of the aryl moiety and the strong steric interactions between the naphthalimide and the aryl ring systems, these compounds can display readily-fine-tuned TICT characters, hence exhibiting an adjustable solvent polarity threshold for aggregation-induced emission (AIE) activity, and could be AIE-active even in less-polar toluene and nonpolar cyclohexane. Furthermore, these compounds could possess highly-pretwisted ground-state geometries, hence could show good EL performance. The findings reveal a facile but effective molecular constructive strategy for versatile, high-performance optoelectronic TICT compounds. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Enhancement of magnetic domain topologies in Co/Pt thin films by fine tuning the magnetic field path throughout the hysteresis loop

    NASA Astrophysics Data System (ADS)

    Westover, Andrew S.; Chesnel, Karine; Hatch, Kelsey; Salter, Philip; Hellwig, Olav

    2016-02-01

    We have studied the influence of magnetic history on the topology of perpendicular magnetic domains in a thin ferromagnetic film made of [Co(8 Å)/Pt(7 Å)]50 multilayers. More specifically, we have followed the morphological changes in the domain pattern when applying a magnetic field perpendicular to the layer, throughout minor and major magnetization loops, and in the resulting remanent state. We carried out this study by using MFM microscopy with an in-situ magnetic field. We find that the morphology of the magnetic domain pattern is greatly influenced by the magnetic history of the material and that some features, such as the degree of bubbliness (i.e., the extent of bubble domain formation) and density of isolated domains can be enhanced by fine tuning the magnetic field path within the major hysteresis loop towards different remanent states. In particular, we see how hysteresis is correlated to irreversible changes in the domain morphology. More interestingly, we find that the magnetic domain morphology at remanence can be changed from an interconnected labyrinthine stripe state to a state of many separated bubble domains by fine tuning the magnitude of the field previously applied to the material. These results agree well with other findings, such as the magnetic reversal behavior and magnetic memory effects in Co/Pt multilayers, and provide opportunities for potential technological applications.

  20. A three-component signalling system fine-tunes expression kinetics of HPPK responsible for folate synthesis by positive feedback loop during stress response of Xanthomonas campestris.

    PubMed

    Wang, Fang-Fang; Deng, Chao-Ying; Cai, Zhen; Wang, Ting; Wang, Li; Wang, Xiao-Zheng; Chen, Xiao-Ying; Fang, Rong-Xiang; Qian, Wei

    2014-07-01

    During adaptation to environments, bacteria employ two-component signal transduction systems, which contain histidine kinases and response regulators, to sense and respond to exogenous and cellular stimuli in an accurate spatio-temporal manner. Although the protein phosphorylation process between histidine kinase and response regulator has been well documented, the molecular mechanism fine-tuning phosphorylation levels of response regulators is comparatively less studied. Here we combined genetic and biochemical approaches to reveal that a hybrid histidine kinase, SreS, is involved in the SreK-SreR phosphotransfer process to control salt stress response in the bacterium Xanthomonas campestris. The N-terminal receiver domain of SreS acts as a phosphate sink by competing with the response regulator SreR to accept the phosphoryl group from the latter's cognate histidine kinase SreK. This regulatory process is critical for bacterial survival because the dephosphorylated SreR protein participates in activating one of the tandem promoters (P2) at the 5' end of the sreK-sreR-sreS-hppK operon, and then modulates a transcriptional surge of the stress-responsive gene hppK, which is required for folic acid synthesis. Therefore, our study dissects the biochemical process of a positive feedback loop in which a 'three-component' signalling system fine-tunes expression kinetics of downstream genes. © 2013 Society for Applied Microbiology and John Wiley & Sons Ltd.

  1. Single-mode tuning of the plasmon resonance in high-density pillar arrays

    NASA Astrophysics Data System (ADS)

    Arnold, Matthew D.

    2017-03-01

    The Maxwell–Garnett (MG) effective medium model has a pure resonance controlled by volume fraction f, but is usually invalid at high density. I present special 2D structures that match quasistatic MG over the entire range 0  <  f  <  1, in several regular and semi-regular arrays, expanding the applicability of MG. Optimal contours depend on both lattice and fill-factor, transforming from circular at low f to nearly polygonal at high f. A key insight is the direct relationship between optimal surface polarization and surface position. Electrodynamic calculations underline the effect of constituent permittivity on spatial dispersion and required sizes for quasistatic response in various materials.

  2. Single-mode tuning of the plasmon resonance in high-density pillar arrays.

    PubMed

    Arnold, Matthew D

    2017-03-22

    The Maxwell-Garnett (MG) effective medium model has a pure resonance controlled by volume fraction f, but is usually invalid at high density. I present special 2D structures that match quasistatic MG over the entire range 0  <  f  <  1, in several regular and semi-regular arrays, expanding the applicability of MG. Optimal contours depend on both lattice and fill-factor, transforming from circular at low f to nearly polygonal at high f. A key insight is the direct relationship between optimal surface polarization and surface position. Electrodynamic calculations underline the effect of constituent permittivity on spatial dispersion and required sizes for quasistatic response in various materials.

  3. Tuning of structural, optical, and magnetic properties of ultrathin and thin ZnO nanowire arrays for nano device applications

    PubMed Central

    2014-01-01

    One-dimensional (1-D) ultrathin (15 nm) and thin (100 nm) aligned 1-D (0001) and (0001¯) oriented zinc oxide (ZnO) nanowire (NW) arrays were fabricated on copper substrates by one-step electrochemical deposition inside the pores of polycarbonate membranes. The aspect ratio dependence of the compressive stress because of the lattice mismatch between NW array/substrate interface and crystallite size variations is investigated. X-ray diffraction results show that the polycrystalline ZnO NWs have a wurtzite structure with a = 3.24 Å, c = 5.20 Å, and [002] elongation. HRTEM and SAED pattern confirmed the polycrystalline nature of ultrathin ZnO NWs and lattice spacing of 0.58 nm. The crystallite size and compressive stress in as-grown 15- and 100-nm wires are 12.8 nm and 0.2248 GPa and 22.8 nm and 0.1359 GPa, which changed to 16.1 nm and 1.0307 GPa and 47.5 nm and 1.1677 GPa after annealing at 873 K in ultrahigh vacuum (UHV), respectively. Micro-Raman spectroscopy showed that the increase in E2 (high) phonon frequency corresponds to much higher compressive stresses in ultrathin NW arrays. The minimum-maximum magnetization magnitude for the as-grown ultrathin and thin NW arrays are approximately 8.45 × 10−3 to 8.10 × 10−3 emu/g and approximately 2.22 × 10−7 to 2.190 × 10−7 emu/g, respectively. The magnetization in 15-nm NW arrays is about 4 orders of magnitude higher than that in the 100 nm arrays but can be reduced greatly by the UHV annealing. The origin of ultrathin and thin NW array ferromagnetism may be the exchange interactions between localized electron spin moments resulting from oxygen vacancies at the surfaces of ZnO NWs. The n-type conductivity of 15-nm NW array is higher by about a factor of 2 compared to that of the 100-nm ZnO NWs, and both can be greatly enhanced by UHV annealing. The ability to tune the stresses and the structural and relative occupancies of ZnO NWs in a wide range by annealing has

  4. 4 T Actively-Detuneable Double-Tuned 1H/31P Head Volume Coil and Four-Channel 31P Phased Array for Human Brain Spectroscopy

    PubMed Central

    Avdievich, N.I.; Hetherington1, H.P.

    2009-01-01

    Typically 31P in vivo magnetic resonance spectroscopic studies are limited by SNR considerations. Although phased arrays can improve the SNR; to date 31P phased arrays for high-field systems have not been combined with 31P volume transmit coils. Additionally, to provide anatomical reference for the 31P studies, without removal of the coil or patient from the magnet, double-tuning (31P/ 1H) of the volume coil is required. In this work we describe a series of methods for active detuning and decoupling enabling use of phased arrays with double-tuned volume coils. To demonstrate these principles we have built and characterized an actively detuneable 31P/1H TEM volume transmit/ four-channel 31P phased array for 4 T magnetic resonance spectroscopic imaging (MRSI) of the human brain. The coil can be used either in volume-transmit/array-receive mode or in TEM transmit/receive mode with the array detuned. Three-fold SNR improvement was obtained at the periphery of the brain using the phased array as compared to the volume coil. PMID:17379554

  5. 4 T Actively detuneable double-tuned 1H/ 31P head volume coil and four-channel 31P phased array for human brain spectroscopy

    NASA Astrophysics Data System (ADS)

    Avdievich, N. I.; Hetherington, H. P.

    2007-06-01

    Typically 31P in vivo magnetic resonance spectroscopic studies are limited by SNR considerations. Although phased arrays can improve the SNR; to date 31P phased arrays for high-field systems have not been combined with 31P volume transmit coils. Additionally, to provide anatomical reference for the 31P studies, without removal of the coil or patient from the magnet, double-tuning ( 31P/ 1H) of the volume coil is required. In this work we describe a series of methods for active detuning and decoupling enabling use of phased arrays with double-tuned volume coils. To demonstrate these principles we have built and characterized an actively detuneable 31P/ 1H TEM volume transmit/four-channel 31P phased array for 4 T magnetic resonance spectroscopic imaging (MRSI) of the human brain. The coil can be used either in volume-transmit/array-receive mode or in TEM transmit/receive mode with the array detuned. Threefold SNR improvement was obtained at the periphery of the brain using the phased array as compared to the volume coil.

  6. High-speed photon energy tuning of x-rays with high duty cycle by use of Clessidra prism arrays

    NASA Astrophysics Data System (ADS)

    Jark, Werner; Last, Arndt; Márkus, Ottó

    2013-09-01

    The refractive index for matter in the hard X-ray range changes rather rapidly with increasing photon energy. In fact away from absorption edges the refractive index decrement varies with the square of the photon energy. As the photon energy dispersion depends on the refractive index decrement, prisms, as used in the visible spectral range, can also be used in the X-ray range for monochromatising or dispersing an incident polychromatic X-ray beam. The dispersion in a single prism is rather small and it is thus mandatory to use ensembles of many prisms for the dispersion process. A particular prism assembly is the Clessidra X-ray lens. The name of the lens, which is Italian for hourglass, describes its appearance as many tiny prisms form two larger prisms with opposing areas. In this form the device can focus an incident plane X-ray wave by refraction. Then the dispersion will make the focusing suffer from chromatic aberrations. The latter can be used in order to operate the structure as a monochromator in combination with an exit slit. For this operation it was found to be advantageous to use a central obstruction in the lens. As the prism array focuses only onedimensionally the object rotation around an axis, which is perpendicular to the incident X-ray beam and which lies in the dispersion plane, is now an available degree of freedom. In a monochromator one can make good use of it, as it permits us to tune the photon energy in a fixed slit. This contribution will discuss the limits for such an operation in terms of achievable spectral resolution and in terms of rapid tuning.

  7. Optimizing the Field Emission Properties of ZnO Nanowire Arrays by Precisely Tuning the Population Density and Application in Large-Area Gated Field Emitter Arrays.

    PubMed

    Li, Yufeng; Zhang, Zhipeng; Zhang, Guofu; Zhao, Long; Deng, Shaozhi; Xu, Ningsheng; Chen, Jun

    2017-02-01

    Zinc oxide (ZnO) nanowires are prepared for application in large area gated field emitter arrays (FEAs). By oxidizing Al-coated Zn films, the population density of the ZnO nanowires was tuned precisely by varying the thickness of the Al film. The nanowire density decreased linearly as the thickness of the Al film increased. Optimal field emission properties with a turn-on field of 6.21 V μm(-1) and current fluctuations less than 1% are obtained. This can be explained by the minimized screening effect and good electrical conductivity of the back-contact layer. The mechanism responsible for the linear variation in the nanowire density is investigated in detail. Addressable FEAs using the optimal ZnO nanowire cathodes were fabricated and applied in a display device. Good gate-controlled characteristics and the display of video images are realized. The results indicate that ZnO nanowires could be applied in large area FEAs.

  8. Self-powered ultraviolet photodetectors based on selectively grown ZnO nanowire arrays with thermal tuning performance.

    PubMed

    Bai, Zhiming; Chen, Xiang; Yan, Xiaoqin; Zheng, Xin; Kang, Zhuo; Zhang, Yue

    2014-05-28

    A self-powered Schottky-type ultraviolet photodetector with Al-Pt interdigitated electrodes has been fabricated based on selectively grown ZnO nanowire arrays. At zero bias, the fabricated photodetector exhibited high sensitivity and excellent selectivity to UV light illumination with a fast response time of 81 ms. By tuning the Schottky barrier height through the thermally induced variation of the interface chemisorbed oxygen, an ultrahigh sensitivity of 3.1 × 10(4) was achieved at 340 K without an external power source, which was 82% higher than that obtained at room temperature. According to the thermionic emission-diffusion theory and the solar cell theory, the changes in the photocurrent of the photodetector at zero bias with various system temperatures were calculated, which agreed well with the experimental data. This work demonstrates a promising approach to modulating the performance of a self-powered photodetector by heating and provides theoretical support for studying the thermal effect on the future photoelectric device.

  9. Applying high-resolution sequence stratigraphic tools to the Texas continental margin to fine-tune conventional sequence stratigraphic models and improve reservoir prediction

    SciTech Connect

    Anderson, J.A.; Banfield, L.A.; Eckles, B.J.

    1996-12-31

    A regional sequence stratigraphic study of the Texas continental margin resulted in an improved understanding of Pleistocene-Holocene eustatic sea level fluctuations and their influence on depositional environments associated with several distinct systems: the Colorado/Brazos system, the Texas interfluve region, and the Rio Grande system. The dataset consists of approximately 7500 kilometers of high-resolution seismic profiloes, 200 borehole descriptions, and 12 sediment cores. The study involved analysis of three independent variables to better constrain Pleistocene-Holocene sea level history: coastal onlap derived from high-resolution seismic profiles; oxygen isotope data determined from selected sediment cores; and paleoenvironmental data developed from high-resolution micropaleontologic analyses. Combined lithologic data and seismic facies analysis is used to map the distribution of major depositional systems on the shelf during one complete glacial eustatic cycle. Our study provided anopportunity to fine tune conventional stratigraphic models with regard to the distribution of potential reservoirs relative to regionally mappable stratigraphic surfaces.

  10. Applying high-resolution sequence stratigraphic tools to the Texas continental margin to fine-tune conventional sequence stratigraphic models and improve reservoir prediction

    SciTech Connect

    Anderson, J.A.; Banfield, L.A.; Eckles, B.J. )

    1996-01-01

    A regional sequence stratigraphic study of the Texas continental margin resulted in an improved understanding of Pleistocene-Holocene eustatic sea level fluctuations and their influence on depositional environments associated with several distinct systems: the Colorado/Brazos system, the Texas interfluve region, and the Rio Grande system. The dataset consists of approximately 7500 kilometers of high-resolution seismic profiloes, 200 borehole descriptions, and 12 sediment cores. The study involved analysis of three independent variables to better constrain Pleistocene-Holocene sea level history: coastal onlap derived from high-resolution seismic profiles; oxygen isotope data determined from selected sediment cores; and paleoenvironmental data developed from high-resolution micropaleontologic analyses. Combined lithologic data and seismic facies analysis is used to map the distribution of major depositional systems on the shelf during one complete glacial eustatic cycle. Our study provided anopportunity to fine tune conventional stratigraphic models with regard to the distribution of potential reservoirs relative to regionally mappable stratigraphic surfaces.

  11. Fine-Tuning of Polymeric Resins and Their Interfaces with Amorphous Calcium Phosphate. A Strategy for Designing Effective Remineralizing Dental Composites.

    PubMed

    Antonucci, Joseph M; Skrtic, Drago

    2010-09-01

    For over a decade our group has been designing, preparing and evaluating bioactive, remineralizing composites based on amorphous calcium phosphate (ACP) fillers embedded in polymerized methacrylate resin matrices. In these studies a major focus has been on exploring structure-property relationships of the matrix phase of these composites on their anti-cariogenic potential. The main challenges were to gain a better understanding of polymer matrix/filler interfacial properties through controlling the surface properties of the fillers or through fine-tuning of the resin matrix. In this work, we describe the effect of chemical structure and composition of the resin matrices on some of the critical physicochemical properties of the copolymers and their ACP composites. Such structure-property studies are essential in formulating clinically effective products, and this knowledge base is likely to have strong impact on the future design of therapeutic materials, appropriate for mineral restoration in defective tooth structures.

  12. Fine-Tuning of Polymeric Resins and Their Interfaces with Amorphous Calcium Phosphate. A Strategy for Designing Effective Remineralizing Dental Composites

    PubMed Central

    Antonucci, Joseph M.; Skrtic, Drago

    2011-01-01

    For over a decade our group has been designing, preparing and evaluating bioactive, remineralizing composites based on amorphous calcium phosphate (ACP) fillers embedded in polymerized methacrylate resin matrices. In these studies a major focus has been on exploring structure-property relationships of the matrix phase of these composites on their anti-cariogenic potential. The main challenges were to gain a better understanding of polymer matrix/filler interfacial properties through controlling the surface properties of the fillers or through fine-tuning of the resin matrix. In this work, we describe the effect of chemical structure and composition of the resin matrices on some of the critical physicochemical properties of the copolymers and their ACP composites. Such structure-property studies are essential in formulating clinically effective products, and this knowledge base is likely to have strong impact on the future design of therapeutic materials, appropriate for mineral restoration in defective tooth structures. PMID:21283507

  13. SpxA1 and SpxA2 Act Coordinately To Fine-Tune Stress Responses and Virulence in Streptococcus pyogenes

    PubMed Central

    Port, Gary C.; Cusumano, Zachary T.; Tumminello, Paul R.

    2017-01-01

    ABSTRACT SpxA is a unique transcriptional regulator highly conserved among members of the phylum Firmicutes that binds RNA polymerase and can act as an antiactivator. Why some Firmicutes members have two highly similar SpxA paralogs is not understood. Here, we show that the SpxA paralogs of the pathogen Streptococcus pyogenes, SpxA1 and SpxA2, act coordinately to regulate virulence by fine-tuning toxin expression and stress resistance. Construction and analysis of mutants revealed that SpxA1− mutants were defective for growth under aerobic conditions, while SpxA2− mutants had severely attenuated responses to multiple stresses, including thermal and oxidative stresses. SpxA1− mutants had enhanced resistance to the cationic antimicrobial molecule polymyxin B, while SpxA2− mutants were more sensitive. In a murine model of soft tissue infection, a SpxA1− mutant was highly attenuated. In contrast, the highly stress-sensitive SpxA2− mutant was hypervirulent, exhibiting more extensive tissue damage and a greater bacterial burden than the wild-type strain. SpxA1− attenuation was associated with reduced expression of several toxins, including the SpeB cysteine protease. In contrast, SpxA2− hypervirulence correlated with toxin overexpression and could be suppressed to wild-type levels by deletion of speB. These data show that SpxA1 and SpxA2 have opposing roles in virulence and stress resistance, suggesting that they act coordinately to fine-tune toxin expression in response to stress. SpxA2− hypervirulence also shows that stress resistance is not always essential for S. pyogenes pathogenesis in soft tissue. PMID:28351920

  14. Maximizing T2-exchange in Dy3+DOTA-(amide)X chelates: Fine-tuning the water molecule exchange rate for enhanced T2 contrast in MRI

    PubMed Central

    Soesbe, Todd C.; Ratnakar, S. James; Milne, Mark; Zhang, Shanrong; Do, Quyen N.; Kovacs, Zoltan; Sherry, A. Dean

    2014-01-01

    Purpose The water molecule exchange rates in a series of DyDOTA-(amide)X chelates were fine-tuned to maximize the effects of T2-exchange line broadening and improve T2 contrast. Methods Four DyDOTA-(amide)X chelates having a variable number of glycinate side-arms were prepared and characterized as T2-exchange agents. The non-exchanging DyTETA chelate was also used to measure the bulk water T2 reduction due solely to T2*. The total transverse relaxivity (r2tot) at 22, 37, and 52 °C for each chelate was measured in vitro at 9.4 T (400 MHz) by fitting plots of total T2−1 versus concentration. The water molecule exchange rates for each complex were measured by fitting 17O line-width versus temperature data taken at 9.4 T (54.3 MHz). Results The measured transverse relaxivities due to water molecule exchange (r2ex) and bound water lifetimes (τM) were in excellent agreement with Swift-Connick theory, with DyDOTA-(gly)3 giving the largest r2ex = 11.8 s−1 mM−1 at 37 °C. Conclusion By fine-tuning the water molecule exchange rate at 37 °C, the transverse relaxivity has been increased by 2 to 30 times compared to previously studied Dy3+-based chelates. Polymerization or dendrimerization of the optimal chelate could yield a highly sensitive, molecule-sized T2 contrast agent for improved molecular imaging applications. PMID:24390729

  15. Fine Tuning of Nanocrystal and Pore Sizes of TiO2 Submicrospheres toward High Performance Dye-Sensitized Solar Cells.

    PubMed

    Li, Zhao-Qian; Ding, Yong; Mo, Li-E; Hu, Lin-Hua; Wu, Ji-Huai; Dai, Song-Yuan

    2015-10-14

    In general, the properties and performance of mesoporous TiO2 are greatly dependent on its crystal size, crystallinity, porosity, surface area, and morphology; in this regard, design and fine-tuning the crystal and pore sizes of the TiO2 submicrospheres and investigating the effect of these factors on the properties and photoelectric performance of dye-sensitized solar cells (DSSCs) is essential. In this work, uniform TiO2 submicrospheres were synthesized by a two-step procedure containing hydrolysis and solvothermal process. The crystal and pore sizes of the TiO2 submicrospheres were fine-tuned and controlled in a narrow range by adjusting the quantity of NH4OH during the solvothermal process. The effect of crystal and pore size of TiO2 submicrosphere on the performance of the DSSCs and their properties including dye-loading capacity, light scattering effect, power conversion efficiency (PCE), incident photon-to-electron conversion efficiencies (IPCEs), and electron recombination were compared and analyzed. The results show that increasing pore size plays a more significant role in improving the dye-loading capacity and PCE than increasing surface area, and an overall PCE value of 8.62% was obtained for the device with a 7.0 μm film thickness based on the TiO2 submicrospheres treated with 0.6 mL of NH4OH. Finally, the best TiO2 submicrosphere based photoanode film was optimized by TiCl4 treatment, and increasing film thickness and a remarkable PCE up to 11.11% were achieved.

  16. Ultra-fine pitch individually addressable visible laser arrays for high speed digital printing applications

    NASA Astrophysics Data System (ADS)

    Kowalski, O. P.; McDougall, S. D.; Qiu, B. C.; Masterton, G. H.; Armstrong, M. L.; Robertson, S.; Caldecott, S.; Marsh, J. H.

    2009-02-01

    An individually addressable visible semiconductor laser diode array with a 20 μm pitch is demonstrated that is highly suited for deployment in next-generation digital print systems. The array, operating at 660 nm, comprises 22 single mode lasers fabricated on a single GaInP/AlGaInP/GaAs substrate. The laser array is flip-chip bonded onto a patterned ceramic submount that enables the individual elements to be driven independently and is integrated into a 26-pin butterfly package. Arrays tested CW exhibit low threshold current (<20 mA per emitter), up to 50 mW output power per channel with a high slope efficiency (0.9 W/A) and a high characteristic temperature of over 100 K.

  17. Fine tuning of emission property of white light-emitting diodes by quantum-dot-coating on YAG:Ce nanophosphors

    NASA Astrophysics Data System (ADS)

    Kong, Dal Sung; Kim, Min Jeong; Song, Hee Jo; Cho, In Sun; Jeong, Sohee; Shin, Hyunjung; Lee, Sangwook; Jung, Hyun Suk

    2016-08-01

    We report fine tuning of emission color of Ce-doped yttrium aluminum garnet (Y3Al5O12:Ce3+, YAG:Ce) nanophosphor-based white light-emitting diodes (WLED), by coating CdSe/CdS/ZnS quantum dots (QDs) onto the surface of the YAG:Ce nanoparticles via surface functionalization of both the QDs and the YAG:Ce. Mixture of bromo-functionalized QDs and amino-functionalized YAG:Ce nanoparticles results in conformal coating of the QDs onto the YAG:Ce nanoparticles (QD@YAG:Ce). By varying the QD to YAG:Ce weight ratios, the luminescence spectra of the QD@YAG:Ce are tuned. A high-quality warm-white-light emission is achieved by appropriate combination of the yellow and red emissions from the QD@YAG:Ce, and the blue emission from InGaN LED chip. However, without surface functionalization, irregular mixtures of YAG:Ce and QDs are formed, which consequently make it hard to control the emission spectra. This study demonstrates a promising way to prepare uniformly QD-coated nanophosphors and an approach to control the emission spectra the nanophosphors.

  18. Design of Far-Red Sensitizing Squaraine Dyes Aiming Towards the Fine Tuning of Dye Molecular Structure.

    PubMed

    Morimoto, Takuya; Fujikawa, Naotaka; Ogomi, Yuhei; Pandey, Shyam S; Ma, Tingli; Hayase, Shuzi

    2016-04-01

    Model squaraine dyes having sharp and narrow absorptions mainly in the far-red wavelength region has been logically designed, synthesized and used for their application as sensitizer in the dyesensitized solar cells (DSSC). In order to have fine control on energetics, dyes having same mother core and alkyl chain length varying only in molecular symmetry and position of substituent were designed. It has been found that even keeping all other structural factor constant, only positional variation of substituent leads to not only in the variation of energetics by 0.1 eV but affects the photovoltaic characteristics also. Optimum concentration of dye de-aggregating agent was found to be 100 times with respect to the sensitizing dye concentration. Amongst dyes utilized in this work best performance was obtained for unsymmetrical dye SQ-40 giving a photoconversion efficiency of 4.01% under simulated solar irradiation at global AM 1.5.

  19. Charge Sharing and Charge Loss in a Cadmium-Zinc-Telluride Fine-Pixel Detector Array

    NASA Technical Reports Server (NTRS)

    Gaskin, J. A.; Sharma, D. P.; Ramsey, B. D.; Six, N. Frank (Technical Monitor)

    2002-01-01

    Because of its high atomic number, room temperature operation, low noise, and high spatial resolution a Cadmium-Zinc-Telluride (CZT) multi-pixel detector is ideal for hard x-ray astrophysical observation. As part of on-going research at MSFC (Marshall Space Flight Center) to develop multi-pixel CdZnTe detectors for this purpose, we have measured charge sharing and charge loss for a 4x4 (750micron pitch), lmm thick pixel array and modeled these results using a Monte-Carlo simulation. This model was then used to predict the amount of charge sharing for a much finer pixel array (with a 300micron pitch). Future work will enable us to compare the simulated results for the finer array to measured values.

  20. High Thermoelectric Power Factor of a Diketopyrrolopyrrole-Based Low Bandgap Polymer via Finely Tuned Doping Engineering

    NASA Astrophysics Data System (ADS)

    Jung, In Hwan; Hong, Cheon Taek; Lee, Un-Hak; Kang, Young Hun; Jang, Kwang-Suk; Cho, Song Yun

    2017-03-01

    We studied the thermoelectric properties of a diketopyrrolopyrrole-based semiconductor (PDPP3T) via a precisely tuned doping process using Iron (III) chloride. In particular, the doping states of PDPP3T film were linearly controlled depending on the dopant concentration. The outstanding Seebeck coefficient of PDPP3T assisted the excellent power factors (PFs) over 200 μW m-1K-2 at the broad range of doping concentration (3-8 mM) and the maximum PF reached up to 276 μW m-1K-2, which is much higher than that of poly(3-hexylthiophene), 56 μW m-1K-2. The high-mobility of PDPP3T was beneficial to enhance the electrical conductivity and the low level of total dopant volume was important to maintain high Seebeck coefficients. In addition, the low bandgap PDPP3T polymer effiectively shifted its absorption into near infra-red area and became more colorless after doping, which is great advantage to realize transparent electronic devices. Our results give importance guidance to develop thermoelectric semiconducting polymers and we suggest that the use of low bandgap and high-mobility polymers, and the accurate control of the doping levels are key factors for obtaining the high thermoelectric PF.

  1. High Thermoelectric Power Factor of a Diketopyrrolopyrrole-Based Low Bandgap Polymer via Finely Tuned Doping Engineering

    PubMed Central

    Jung, In Hwan; Hong, Cheon Taek; Lee, Un-Hak; Kang, Young Hun; Jang, Kwang-Suk; Cho, Song Yun

    2017-01-01

    We studied the thermoelectric properties of a diketopyrrolopyrrole-based semiconductor (PDPP3T) via a precisely tuned doping process using Iron (III) chloride. In particular, the doping states of PDPP3T film were linearly controlled depending on the dopant concentration. The outstanding Seebeck coefficient of PDPP3T assisted the excellent power factors (PFs) over 200 μW m−1K−2 at the broad range of doping concentration (3–8 mM) and the maximum PF reached up to 276 μW m−1K−2, which is much higher than that of poly(3-hexylthiophene), 56 μW m−1K−2. The high-mobility of PDPP3T was beneficial to enhance the electrical conductivity and the low level of total dopant volume was important to maintain high Seebeck coefficients. In addition, the low bandgap PDPP3T polymer effiectively shifted its absorption into near infra-red area and became more colorless after doping, which is great advantage to realize transparent electronic devices. Our results give importance guidance to develop thermoelectric semiconducting polymers and we suggest that the use of low bandgap and high-mobility polymers, and the accurate control of the doping levels are key factors for obtaining the high thermoelectric PF. PMID:28317929

  2. Photochemical fine-tuning of luminescent color of cadmium selenide nanoparticles: fabricating a single-source multicolor luminophore.

    PubMed

    Torimoto, Tsukasa; Murakami, Shin-ya; Sakuraoka, Miwa; Iwasaki, Kentaro; Okazaki, Ken-ichi; Shibayama, Tamaki; Ohtani, Bunsho

    2006-07-13

    Size-selective photoetching was applied to silica-coated cadmium selenide (SiO2/CdSe) nanoparticles to precisely control their photoluminescence properties. The absorption spectra of CdSe was blue-shifted by irradiation of monochromatic light, and finally, the absorption onset agreed with the wavelength of irradiation light, indicating that CdSe particles were photoetched to smaller ones until the irradiated photons were not absorbed by the photoetched particles and that the SiO2 shell layer surrounding the CdSe core prevented coalescence between the photoetched particles. Although as-prepared SiO2/CdSe did not exhibit photoluminescence, the application of size-selective photoetching to SiO2/CdSe resulted in the development of the band gap emission, with the degree being enhanced with progress of the photoetching. The peak wavelength of photoluminescence decreased with a decrease in the wavelength used for the photoetching, so that the luminescence color could be tuned between red and blue. Partial photoetching of SiO2/CdSe nanoparticle films produced intense band gap emission of CdSe at the photoetched area, while the remainder of the SiO2/CdSe films did not exhibit detectable photoluminescence, resulting in the formation of a clear photoluminescence image under UV irradiation. This technique makes it possible to produce a multicolored photoluminescence image by irradiation with monochromatic lights having various wavelengths using a single source material.

  3. Fine tuning of copper(II)-chlorophyll interactions in organic media. Metalation versus oxidation of the macrocycle.

    PubMed

    Orzeł, Łukasz; Szmyd, Bartłomiej; Rutkowska-Żbik, Dorota; Fiedor, Leszek; van Eldik, Rudi; Stochel, Grażyna

    2015-04-07

    The nature of chlorophyll interactions with copper(II) ions varies considerably in organic solvents, depending on the dominant coordinative form. Besides formation of the metallo tetrapyrrolic complex, Cu(II) ions can cause oxidation of the pigment, reversible or irreversible, which can lead to the destruction of the macrocyclic structure. All these reaction types can be distinguished within a quite narrow range of reaction conditions. The ability to form new metallo derivatives in either metalation or transmetalation reactions is obviously limited by the concentration of the potential oxidant, but can be secured below this level via suitable composition of the reaction system. The decisive factor in the selection of a specific reaction pathway is the presence of a potential ligand that can affect the reactivity of Cu(II) for example by shifting its redox potential. Spectroscopic and electrochemical studies were performed in order to determine the predominant species of Cu(II) in methanol, nitromethane and acetonitrile in the presence of chloride and acetate ions, as well as to assign their appropriate oxidizing ability. This allowed us to estimate the boundary conditions for the electron transfer processes in chlorophyll-Cu(II) systems. Chlorophyll and its free base can undergo both types of electron transfer processes, however, they reveal different susceptibilities that make this class of ligands quite versatile markers in tuning the reactivity of metal ions in solutions.

  4. Single side strapping: a new approach to fine tuning the anion recognition properties of calix[4]pyrroles.

    PubMed

    Lee, Chang-Hee; Na, Hee-Kyung; Yoon, Dae-Wi; Won, Dong-Hoon; Cho, Won-Seob; Lynch, Vincent M; Shevchuk, Sergey V; Sessler, Jonathan L

    2003-06-18

    Three calix[4]pyrroles bearing m-orcinol-derived diether straps of different lengths on one side of the tetrapyrrolic core have been synthesized and characterized. Structural information for an analogous diester bridged strapped system reported previously (Yoon, D. W.; Hwang, H.; Lee, C. H. Angew. Chem., Int. Ed. Engl. 2002, 41, 1757-1759) is also provided as are bromide and chloride anion affinities for all four systems determined by Isothermal Titration Calorimetry (ITC) in acetonitrile. Although both sets of the strapped calix[4]pyrroles displayed enhanced affinities for chloride and bromide anion, differences were seen among the various receptors that support the conclusion that the anion binding ability of calixpyrrole-type systems can be effectively tuned by modifying the length and nature of the bridging straps. In the specific case of the diether systems, the largest chloride affinity was seen with the shortest strap, whereas the largest affinity for bromide anion was recorded in the case of the longest strap. On the basis of these findings, as well as supporting (1)H NMR spectroscopic studies, it is postulated that not only cavity size per se, but also the ability of the aryl portion of the strap to serve as a CH hydrogen bond donor site are important in regulating the observed anion affinities.

  5. Fine mapping of copy number variations on two cattle genome assemblies using high density SNP array

    USDA-ARS?s Scientific Manuscript database

    Btau_4.0 and UMD3.1 are two distinct cattle reference genome assemblies. In our previous study using the low density BovineSNP50 array, we reported a copy number variation (CNV) analysis on Btau_4.0 with 521 animals of 21 cattle breeds, yielding 682 CNV regions with a total length of 139.8 megabases...

  6. Structural control of ultra-fine CoPt nanodot arrays via electrodeposition process

    NASA Astrophysics Data System (ADS)

    Wodarz, Siggi; Hasegawa, Takashi; Ishio, Shunji; Homma, Takayuki

    2017-05-01

    CoPt nanodot arrays were fabricated by combining electrodeposition and electron beam lithography (EBL) for the use of bit-patterned media (BPM). To achieve precise control of deposition uniformity and coercivity of the CoPt nanodot arrays, their crystal structure and magnetic properties were controlled by controlling the diffusion state of metal ions from the initial deposition stage with the application of bath agitation. Following bath agitation, the composition gradient of the CoPt alloy with thickness was mitigated to have a near-ideal alloy composition of Co:Pt =80:20, which induces epitaxial-like growth from Ru substrate, thus resulting in the improvement of the crystal orientation of the hcp (002) structure from its initial deposition stages. Furthermore, the cross-sectional transmission electron microscope (TEM) analysis of the nanodots deposited with bath agitation showed CoPt growth along its c-axis oriented in the perpendicular direction, having uniform lattice fringes on the hcp (002) plane from the Ru underlayer interface, which is a significant factor to induce perpendicular magnetic anisotropy. Magnetic characterization of the CoPt nanodot arrays showed increase in the perpendicular coercivity and squareness of the hysteresis loops from 2.0 kOe and 0.64 (without agitation) to 4.0 kOe and 0.87 with bath agitation. Based on the detailed characterization of nanodot arrays, the precise crystal structure control of the nanodot arrays with ultra-high recording density by electrochemical process was successfully demonstrated.

  7. Mapping the fine structure of cortical activity with different micro-ECoG electrode array geometries

    NASA Astrophysics Data System (ADS)

    Wang, Xi; Gkogkidis, C. Alexis; Iljina, Olga; Fiederer, Lukas D. J.; Henle, Christian; Mader, Irina; Kaminsky, Jan; Stieglitz, Thomas; Gierthmuehlen, Mortimer; Ball, Tonio

    2017-10-01

    Objective. Innovations in micro-electrocorticography (µECoG) electrode array manufacturing now allow for intricate designs with smaller contact diameters and/or pitch (i.e. inter-contact distance) down to the sub-mm range. The aims of the present study were: (i) to investigate whether frequency ranges up to 400 Hz can be reproducibly observed in µECoG recordings and (ii) to examine how differences in topographical substructure between these frequency bands and electrode array geometries can be quantified. We also investigated, for the first time, the influence of blood vessels on signal properties and assessed the influence of cortical vasculature on topographic mapping. Approach. The present study employed two µECoG electrode arrays with different contact diameters and inter-contact distances, which were used to characterize neural activity from the somatosensory cortex of minipigs in a broad frequency range up to 400 Hz. The analysed neural data were recorded in acute experiments under anaesthesia during peripheral electrical stimulation. Main results. We observed that µECoG recordings reliably revealed multi-focal cortical somatosensory response patterns, in which response peaks were often less than 1 cm apart and would thus not have been resolvable with conventional ECoG. The response patterns differed by stimulation site and intensity, they were distinct for different frequency bands, and the results of functional mapping proved independent of cortical vascular. Our analysis of different frequency bands exhibited differences in the number of activation peaks in topographical substructures. Notably, signal strength and signal-to-noise ratios differed between the two electrode arrays, possibly due to their different sensitivity for variations in spatial patterns and signal strengths. Significance. Our findings that the geometry of µECoG electrode arrays can strongly influence their recording performance can help to make informed decisions that maybe

  8. Mapping the fine structure of cortical activity with different micro-ECoG electrode array geometries.

    PubMed

    Wang, Xi; Gkogkidis, C Alexis; Iljina, Olga; Fiederer, Lukas D J; Henle, Christian; Mader, Irina; Kaminsky, Jan; Stieglitz, Thomas; Gierthmuehlen, Mortimer; Ball, Tonio

    2017-10-01

    Innovations in micro-electrocorticography (µECoG) electrode array manufacturing now allow for intricate designs with smaller contact diameters and/or pitch (i.e. inter-contact distance) down to the sub-mm range. The aims of the present study were: (i) to investigate whether frequency ranges up to 400 Hz can be reproducibly observed in µECoG recordings and (ii) to examine how differences in topographical substructure between these frequency bands and electrode array geometries can be quantified. We also investigated, for the first time, the influence of blood vessels on signal properties and assessed the influence of cortical vasculature on topographic mapping. The present study employed two µECoG electrode arrays with different contact diameters and inter-contact distances, which were used to characterize neural activity from the somatosensory cortex of minipigs in a broad frequency range up to 400 Hz. The analysed neural data were recorded in acute experiments under anaesthesia during peripheral electrical stimulation. We observed that µECoG recordings reliably revealed multi-focal cortical somatosensory response patterns, in which response peaks were often less than 1 cm apart and would thus not have been resolvable with conventional ECoG. The response patterns differed by stimulation site and intensity, they were distinct for different frequency bands, and the results of functional mapping proved independent of cortical vascular. Our analysis of different frequency bands exhibited differences in the number of activation peaks in topographical substructures. Notably, signal strength and signal-to-noise ratios differed between the two electrode arrays, possibly due to their different sensitivity for variations in spatial patterns and signal strengths. Our findings that the geometry of µECoG electrode arrays can strongly influence their recording performance can help to make informed decisions that maybe important in number of clinical contexts, including

  9. Fine-tuning notes in the behavioral symphony: parent-of-origin allelic gene expression in the brain.

    PubMed

    Sittig, Laura J; Redei, Eva E

    2014-01-01

    The gene encoding the thyroid hormone (TH)-metabolizing enzyme, deiodinase type III (Dio3), exhibits a preferential paternal expression in most tissues. Dio3 is part of the Dlk1-Dio3 imprinted locus, so named according to its ancestral genes, Delta-like homolog 1 (Dlk1) and Dio3, which among other important functions control metabolic programming in the developing embryo and fetus. Here, we describe the aspects of the genomic imprinting patterns exhibited by Dio3 across brain regions and development. The corresponding local changes in the dosage of the Dio3 enzyme are inversely related to TH levels that vary from one brain region to another, and affect social and cognitive behaviors. We show that this regional tuning of brain region-specific expression is dependent on parent of origin-specific genetic polymorphisms in the rat, is sexually dimorphic, and is affected by the early environmental challenge of fetal exposure to alcohol, opening the possibility that the potential for variant expression patterns of the Dio3 gene is quite large. The multiple regulatory genomic features within the Dlk1-Dio3 locus, and other imprinted loci, allow mammals to specifically modulate parent-of-origin allelic gene expression brain region. These regulatory structures seem to have evolved as a possible mechanism of adaptation in response to the simultaneous need for highly regulated expression in some tissues during development, but variable expression across specific regions of the brain over the complete life span. Here, we use Dio3 as a single gene example of the epigenetic parent-of-origin allelic expression in specific brain regions and discuss the potential of this general phenomenon to shape evolutionarily relevant social and cognitive behavior in eutherian mammals. Copyright © 2014 Elsevier Inc. All rights reserved.

  10. Conference on Children and Television: Worldwide Fine Tuning for Children, University of Miami, Parts I and II. Transcript of the Panel Discussion on the Television Series "Big Blue Marble"

    ERIC Educational Resources Information Center

    Brown, Les; And Others

    This paper describes the proceedings of a conference on children and television, "Worldwide Fine Tuning for Children," held on 11 February 1977 by the University of Miami Department of Communications. The purpose of the conference was to survey the world of television as experienced by children and to explore how communications experts,…

  11. Conference on Children and Television: Worldwide Fine Tuning for Children, University of Miami, Parts I and II. Transcript of the Panel Discussion on the Television Series "Big Blue Marble"

    ERIC Educational Resources Information Center

    Brown, Les; And Others

    This paper describes the proceedings of a conference on children and television, "Worldwide Fine Tuning for Children," held on 11 February 1977 by the University of Miami Department of Communications. The purpose of the conference was to survey the world of television as experienced by children and to explore how communications experts,…

  12. Perilipin 5 fine-tunes lipid oxidation to metabolic demand and protects against lipotoxicity in skeletal muscle

    PubMed Central

    Laurens, Claire; Bourlier, Virginie; Mairal, Aline; Louche, Katie; Badin, Pierre-Marie; Mouisel, Etienne; Montagner, Alexandra; Marette, André; Tremblay, Angelo; Weisnagel, John S.; Guillou, Hervé; Langin, Dominique; Joanisse, Denis R.; Moro, Cedric

    2016-01-01

    Lipid droplets (LD) play a central role in lipid homeostasis by controlling transient fatty acid (FA) storage and release from triacylglycerols stores, while preventing high levels of cellular toxic lipids. This crucial function in oxidative tissues is altered in obesity and type 2 diabetes. Perilipin 5 (PLIN5) is a LD protein whose mechanistic and causal link with lipotoxicity and insulin resistance has raised controversies. We investigated here the physiological role of PLIN5 in skeletal muscle upon various metabolic challenges. We show that PLIN5 protein is elevated in endurance-trained (ET) subjects and correlates with muscle oxidative capacity and whole-body insulin sensitivity. When overexpressed in human skeletal muscle cells to recapitulate the ET phenotype, PLIN5 diminishes lipolysis and FA oxidation under basal condition, but paradoxically enhances FA oxidation during forskolin- and contraction- mediated lipolysis. Moreover, PLIN5 partly protects muscle cells against lipid-induced lipotoxicity. In addition, we demonstrate that down-regulation of PLIN5 in skeletal muscle inhibits insulin-mediated glucose uptake under normal chow feeding condition, while paradoxically improving insulin sensitivity upon high-fat feeding. These data highlight a key role of PLIN5 in LD function, first by finely adjusting LD FA supply to mitochondrial oxidation, and second acting as a protective factor against lipotoxicity in skeletal muscle. PMID:27922115

  13. Fine-tuned regulation of the K(+) /H(+) antiporter KEA3 is required to optimize photosynthesis during induction.

    PubMed

    Wang, Caijuan; Yamamoto, Hiroshi; Narumiya, Fumika; Munekage, Yuri Nakajima; Finazzi, Giovanni; Szabo, Ildiko; Shikanai, Toshiharu

    2017-02-01

    KEA3 is a thylakoid membrane localized K(+) /H(+) antiporter that regulates photosynthesis by modulating two components of proton motive force (pmf), the proton gradient (∆pH) and the electric potential (∆ψ). We identified a mutant allele of KEA3, disturbed proton gradient regulation (dpgr) based on its reduced non-photochemical quenching (NPQ) in artificial (CO2 -free with low O2 ) air. This phenotype was enhanced in the mutant backgrounds of PSI cyclic electron transport (pgr5 and crr2-1). In ambient air, reduced NPQ was observed during induction of photosynthesis in dpgr, the phenotype that was enhanced after overnight dark adaptation. In contrast, the knockout allele of kea3-1 exhibited a high-NPQ phenotype during steady state in ambient air. Consistent with this kea3-1 phenotype in ambient air, the membrane topology of KEA3 indicated a proton efflux from the thylakoid lumen to the stroma. The dpgr heterozygotes showed a semidominant and dominant phenotype in artificial and ambient air, respectively. In dpgr, the protein level of KEA3 was unaffected but the downregulation of its activity was probably disturbed. Our findings suggest that fine regulation of KEA3 activity is necessary for optimizing photosynthesis.

  14. The fine-tuning of thermosensitive and degradable polymer micelles for enhancing intracellular uptake and drug release in tumors.

    PubMed

    Li, Wei; Li, Jinfeng; Gao, Jie; Li, Bohua; Xia, Yu; Meng, Yanchun; Yu, Yongsheng; Chen, Huaiwen; Dai, Jianxin; Wang, Hao; Guo, Yajun

    2011-05-01

    Focusing on high temperature and low pH of tumor tissue, we prepared temperature and pH responsive poly(N-isopropylacrylamide-co-N,N-dimethylacrylamide-b-lacitde) (PID(118)-b-PLA(59)) and poly(N-isopropylacrylamide-co-N,N-dimethylacrylamide-b-ε-caprolactone) (PID(118)-b-PCL(60)) diblock copolymers with symmetric hydrophobic blocks by the reversible addition-fragmentation chain transfer (RAFT). The corresponding dual functional polymeric micelles were fabricated by dialysis methods. Their well-defined core-shell structure was characterized by (1)H NMR in D(2)O and further confirmed by TEM. Their structural and physical chemistry properties such as diameters (D), core corona dimension (R(core), R(shell)), distribution (PDI), M(w), aggregation number (N(agg)), second virial coefficient (A(2)), critical micellization concentration (CMC) and z-potential were firstly systemically investigated by dynamic and static laser light scattering. The volume phase transition temperature (VPTT) was around 40 °C above which the intracellular uptake of adriamycin (ADR) was significantly enhanced. Both flow cytometry and fluorescent microscopy showed that the ADR transported by these micelles was about 4 times higher than that by the commercial ADR formulation Taxotere®. In vitro cytotoxicity assay against N-87 cancer cell and confocal laser scanning microscopy (CLSM) also confirmed such promoting efficiency. In addition, it was interesting to find that cell surviving bounced back as T = 42 °C due to the inter-micellar aggregation. The well clarified mechanism strongly support that our finely tailored dual functional core-shell micelles are potent in enhancing cellular uptake and drug release.

  15. Fine-Tuning of the Carbon Dioxide Capture Capability of Diamine-Grafted Metal-Organic Framework Adsorbents Through Amine Functionalization.

    PubMed

    Jo, Hyuna; Lee, Woo Ram; Kim, Nam Woo; Jung, Hyun; Lim, Kwang Soo; Kim, Jeong Eun; Kang, Dong Won; Lee, Hanyeong; Hiremath, Vishwanath; Seo, Jeong Gil; Jin, Hailian; Moon, Dohyun; Han, Sang Soo; Hong, Chang Seop

    2017-02-08

    A combined sonication and microwave irradiation procedure provides the most effective functionalization of ethylenediamine (en) and branched primary diamines of 1-methylethylenediamine (men) and 1,1-dimethylethylenediamine (den) onto the open metal sites of Mg2 (dobpdc) (1). The CO2 capacities of the advanced adsorbents 1-en and 1-men under simulated flue gas conditions are 19 wt % and 17.4 wt %, respectively, which are the highest values reported among amine-functionalized metal-organic frameworks (MOFs) to date. Moreover, 1-den exhibits both a significant working capacity (12.2 wt %) and superb CO2 uptake (11 wt %) at 3 % CO2 . Additionally, this framework showcases the superior recyclability; ultrahigh stability after exposure to O2 , moisture, and SO2 ; and exceptional CO2 adsorption capacity under humid conditions, which are unprecedented among MOFs. We also elucidate that the performance of CO2 adsorption can be controlled by the structure of the diamine ligands grafted such as the number of amine end groups or the presence of side groups, which provides the first systematic and comprehensive demonstration of fine-tuning of CO2 uptake capability using different amines.

  16. Sox2 in the dermal papilla niche controls hair growth by fine-tuning Bmp signaling in differentiating hair shaft progenitors

    PubMed Central

    Clavel, Carlos; Grisanti, Laura; Zemla, Roland; Rezza, Amelie; Barros, Rita; Sennett, Rachel; Mazloom, Amin; Chung, Chi-Yeh; Cai, Xiaoqiang; Cai, Chen-Leng; Pevny, Larysa; Nicolis, Silvia; Ma’ayan, Avi; Rendl, Michael

    2012-01-01

    SUMMARY How dermal papilla (DP) niche cells regulate hair follicle progenitors to control hair growth remains unclear. Using Tbx18Cre to target embryonic DP precursors, we ablate the transcription factor Sox2 early and efficiently, resulting in diminished hair shaft outgrowth. We find that DP niche expression of Sox2 controls the migration rate of differentiating hair shaft progenitors. Transcriptional profiling of Sox2 null DPs reveals increased Bmp6 and decreased Bmp inhibitor Sostdc1, a direct Sox2 transcriptional target. Subsequently, we identify upregulated Bmp signaling in knockout hair shaft progenitors and demonstrate that Bmps inhibit cell migration, an effect that can be attenuated by Sostdc1. A shorter and Sox2-negative hair type lacks Sostdc1 in the DP and shows reduced migration and increased Bmp activity of hair shaft progenitors. Collectively, our data identify Sox2 as a key regulator of hair growth that controls progenitor migration by fine-tuning Bmp-mediated mesenchymal-epithelial crosstalk. PMID:23153495

  17. Full phosphorescent white-light organic light-emitting diodes with improved color stability and efficiency by fine tuning primary emission contributions

    SciTech Connect

    Hua, Wang E-mail: wanghua001@tyut.edu.cn; Du, Xiaogang; Su, Wenming E-mail: wanghua001@tyut.edu.cn; Zhang, Dongyu; Lin, Wenjing

    2014-02-15

    In this paper, a novel type of white-light organic light emitting diode (OLED) with high color stability was reported, in which the yellow-light emission layer of (4,4{sup ′}-N,N{sup ′}-dicarbazole)biphenyl (CBP) : tris(2-phenylquinoline-C2,N{sup ′})iridium(III) (Ir(2-phq){sub 3}) was sandwiched by double blue-light emission layers of 1,1-bis-[(di-4-tolylamino)pheny1]cyclohexane (TAPC) : bis[4,6-(di-fluorophenyl)-pyridinato-N,C2{sup ′}]picolinate (FIrpic) and tris[3-(3-pyridyl)mesityl]borane (3TPYMB):FIrpic. And, it exhibited the maximum current efficiency of 33.1 cd/A, the turn-on voltage at about 3 V and the maximum luminance in excess of 20000 cd/m{sup 2}. More important, it realized very stable white-light emission, and its CIE(x, y) coordinates only shift from (0.34, 0.37) to (0.33, 0.37) as applied voltage increased from 5 V to 12 V. It is believed that the new scheme in emission layer of white-light OLED can fine tune the contribution of primary emission with applied voltage changed, resulting in high quality white-light OLED.

  18. Plasma Membrane CRPK1-Mediated Phosphorylation of 14-3-3 Proteins Induces Their Nuclear Import to Fine-Tune CBF Signaling during Cold Response.

    PubMed

    Liu, Ziyan; Jia, Yuxin; Ding, Yanglin; Shi, Yiting; Li, Zhen; Guo, Yan; Gong, Zhizhong; Yang, Shuhua

    2017-04-06

    In plant cells, changes in fluidity of the plasma membrane may serve as the primary sensor of cold stress; however, the precise mechanism and how the cell transduces and fine-tunes cold signals remain elusive. Here we show that the cold-activated plasma membrane protein cold-responsive protein kinase 1 (CRPK1) phosphorylates 14-3-3 proteins. The phosphorylated 14-3-3 proteins shuttle from the cytosol to the nucleus, where they interact with and destabilize the key cold-responsive C-repeat-binding factor (CBF) proteins. Consistent with this, the crpk1 and 14-3-3κλ mutants show enhanced freezing tolerance, and transgenic plants overexpressing 14-3-3λ show reduced freezing tolerance. Further study shows that CRPK1 is essential for the nuclear translocation of 14-3-3 proteins and for 14-3-3 function in freezing tolerance. Thus, our study reveals that the CRPK1-14-3-3 module transduces the cold signal from the plasma membrane to the nucleus to modulate CBF stability, which ensures a faithfully adjusted response to cold stress of plants. Copyright © 2017 Elsevier Inc. All rights reserved.

  19. The CCR4 deadenylase acts with Nanos and Pumilio in the fine-tuning of Mei-P26 expression to promote germline stem cell self-renewal.

    PubMed

    Joly, Willy; Chartier, Aymeric; Rojas-Rios, Patricia; Busseau, Isabelle; Simonelig, Martine

    2013-01-01

    Translational regulation plays an essential role in Drosophila ovarian germline stem cell (GSC) biology. GSC self-renewal requires two translational repressors, Nanos (Nos) and Pumilio (Pum), which repress the expression of differentiation factors in the stem cells. The molecular mechanisms underlying this translational repression remain unknown. Here, we show that the CCR4 deadenylase is required for GSC self-renewal and that Nos and Pum act through its recruitment onto specific mRNAs. We identify mei-P26 mRNA as a direct and major target of Nos/Pum/CCR4 translational repression in the GSCs. mei-P26 encodes a protein of the Trim-NHL tumor suppressor family that has conserved functions in stem cell lineages. We show that fine-tuning Mei-P26 expression by CCR4 plays a key role in GSC self-renewal. These results identify the molecular mechanism of Nos/Pum function in GSC self-renewal and reveal the role of CCR4-NOT-mediated deadenylation in regulating the balance between GSC self-renewal and differentiation.

  20. Listeria monocytogenes CadC regulates cadmium efflux and fine-tunes lipoprotein localization to escape the host immune response and promote infection.

    PubMed

    Pombinho, Rita; Camejo, Ana; Vieira, Ana; Reis, Olga; Carvalho, Filipe; Almeida, Maria Teresa; Pinheiro, Jorge Campos; Sousa, Sandra; Cabanes, Didier

    2017-03-23

    Listeria monocytogenes (Lm) is a major intracellular human foodborne bacterial pathogen. We previously revealed Lm-cadC as highly expressed during mouse infection. Here we show that Lm-CadC is a sequence-specific, DNA-binding and cadmium-dependent regulator of CadA, an efflux pump conferring cadmium resistance. CadC, but not CadA, is required for Lm infection in vivo. Interestingly, CadC also directly represses lspB, a gene encoding a lipoprotein signal peptidase whose expression appears detrimental for infection. lspB overexpression promotes the release of the LpeA lipoprotein to the extracellular medium, inducing TNF- and IL-6 expression, thus impairing Lm survival in macrophages. We propose that Lm uses CadC to repress lspB expression during infection to avoid LpeA exposure to the host immune system, diminishing inflammatory cytokine expression and promoting intramacrophage survival and virulence. CadC appears as the first metal efflux pump regulator repurposed during infection to fine-tune lipoprotein processing and host responses.

  1. Fine-tuning of NFκB by Glycogen Synthase Kinase 3β directs the fate of glomerular podocytes upon injury

    PubMed Central

    Bao, Hui; Ge, Yan; Peng, Ai; Gong, Rujun

    2014-01-01

    NFκB is regulated by a myriad of signaling cascades including glycogen synthase kinase (GSK) 3β and plays a Janus role in podocyte injury. In vitro, lipopolysaccharide or adriamycin elicited podocyte injury and cytoskeletal disruption, associated with NFκB activation and induced expression of NFκB target molecules, including pro-survival Bcl-xL and podocytopathic mediators like MCP-1, cathepsin L and B7-1. Broad range inhibition of NFκB diminished the expression of all NFκB target genes, restored cytoskeleton integrity, but potentiated apoptosis. In contrast, blockade of GSK3β by lithium or TDZD-8, mitigated the expression of podocytopathic mediators, ameliorated podocyte injury, but barely affected Bcl-xL expression or sensitized apoptosis. Mechanistically, GSK3β was sufficient and essential for RelA/p65 phosphorylation specifically at serine 467, which specifies the expression of selective NFκB target molecules, including podocytopathic mediators, but not Bcl-xL. In vivo, lithium or TDZD-8 therapy improved podocyte injury and proteinuria in mice treated with lipopolysaccharide or adriamycin, concomitant with suppression of podocytopathic mediators but retained Bcl-xL in glomerulus. Broad range inhibition of NFκB conferred similar but much weakened antiproteinuric and podoprotective effects accompanied with a blunted glomerular expression of Bcl-xL and marked podocyte apoptosis. Thus, the GSK3β dictated fine-tuning of NFκB may serve as a novel therapeutic target for podocytopathy. PMID:25629551

  2. Preserved fine-tuning of face perception and memory: evidence from the own-race bias in high- and low-performing older adults

    PubMed Central

    Komes, Jessica; Schweinberger, Stefan R.; Wiese, Holger

    2014-01-01

    Previous research suggests specific deficits in face perception and memory in older adults, which could reflect a dedifferentiation in the context of a general broadening of cognitive architecture with advanced age. Such dedifferentiation could manifest in a less specialized face processing system. A promising tool to investigate the fine-tuning of face processing in older age is the own-race bias (ORB), a phenomenon reflecting more accurate memory for own-relative to other-race faces, which is related to an expertise-based specialization of early perceptual stages. To investigate whether poor face memory in older age is accompanied by reduced expertise-based specialization of face processing, we assessed event-related brain potential correlates of the ORB in high- vs. low-performing older adults (mean age = 69 years; N = 24 per group). Intriguingly, both older groups demonstrated an equivalent pattern of a behavioral ORB, and a parallel increase in N170 for other-race faces, reflecting less efficient early perceptual processing for this face category. Group differences only emerged independent of face ethnicity: whereas low-performers exhibited a right-lateralized N170, high-performers showed a more bilateral response. This finding may suggest a compensatory mechanism counteracting age-related decline in face perception enabling more efficient encoding into memory in high performers. Overall, our results demonstrate that even a less efficient face processing system in older adults can exhibit preserved expertise-related specialization toward own-race faces. PMID:24772080

  3. Fine-Tuning of the Coordination Environment To Regulate the Magnetic Behavior in Solvent/Anion-Dependent Dy(III) Compounds: Synthesis, Structure, Magnetism, and Ab Initio Calculations.

    PubMed

    Sun, Lin; Zhang, Sheng; Qiao, Chengfang; Chen, Sanping; Yin, Bing; Wang, Wenyuan; Wei, Qing; Xie, Gang; Gao, Shengli

    2016-10-17

    It is crucial to understand and elucidate the self-assembly mechanism in solution systems for the construction of Dy(III)-based single-molecule magnets (SMMs). Herein, through fine-tuning of the anion and solvent, we prepared three nine-coordinate mononuclear dysprosium compounds, [Dy(2,3'-pcad)(NO3)2(CH3OH)2] (1), [Dy(2,3'-Hpcad)2(H2O)3]·3Cl·5H2O (2), and [Dy(2,3'-pcad)(NO3)(H2O)4]·NO3·H2O (3) [2,3'-Hpcad = N(3)-(2-pyridoyl)-3-pyridinecarboxamidrazone]. The reactions of formation for 1-3 are in situ thermodynamically monitored by isothermal titration calorimetry. Magnetic data analysis reveals that 2 shows SMM behavior under a zero direct-current (dc) field, whereas 1 and 3 exhibit distinct slow magnetic relaxation processes upon a 1200 Oe dc field. To deeply understand the different magnetic behaviors, the magnetic anisotropy of 1-3 has been systematically studied by ab initio calculations, which is consistent with the experimental observations. Moreover, the semiconductor behaviors of 1-3 have been investigated by experimental measurements of UV-vis spectroscopy.

  4. Enzymatic profiling of cellulosomal enzymes from the human gut bacterium, Ruminococcus champanellensis, reveals a fine-tuned system for cohesin-dockerin recognition.

    PubMed

    Moraïs, Sarah; Ben David, Yonit; Bensoussan, Lizi; Duncan, Sylvia H; Koropatkin, Nicole M; Martens, Eric C; Flint, Harry J; Bayer, Edward A

    2016-02-01

    Ruminococcus champanellensis is considered a keystone species in the human gut that degrades microcrystalline cellulose efficiently and contains the genetic elements necessary for cellulosome production. The basic elements of its cellulosome architecture, mainly cohesin and dockerin modules from scaffoldins and enzyme-borne dockerins, have been characterized recently. In this study, we cloned, expressed and characterized all of the glycoside hydrolases that contain a dockerin module. Among the 25 enzymes, 10 cellulases, 4 xylanases, 3 mannanases, 2 xyloglucanases, 2 arabinofuranosidases, 2 arabinanases and one β-glucanase were assessed for their comparative enzymatic activity on their respective substrates. The dockerin specificities of the enzymes were examined by ELISA, and 80 positives out of 525 possible interactions were detected. Our analysis reveals a fine-tuned system for cohesin-dockerin specificity and the importance of diversity among the cohesin-dockerin sequences. Our results imply that cohesin-dockerin pairs are not necessarily assembled at random among the same specificity types, as generally believed for other cellulosome-producing bacteria, but reveal a more organized cellulosome architecture. Moreover, our results highlight the importance of the cellulosome paradigm for cellulose and hemicellulose degradation by R. champanellensis in the human gut. © 2015 Society for Applied Microbiology and John Wiley & Sons Ltd.

  5. MicroRNA-29 Fine-tunes the Expression of Key FOXA2-Activated Lipid Metabolism Genes and Is Dysregulated in Animal Models of Insulin Resistance and Diabetes

    PubMed Central

    Kurtz, C. Lisa; Peck, Bailey C.E.; Fannin, Emily E.; Beysen, Carine; Miao, Ji; Landstreet, Stuart R.; Ding, Shengli; Turaga, Vandana; Lund, P. Kay; Turner, Scott; Biddinger, Sudha B.; Vickers, Kasey C.

    2014-01-01

    MicroRNAs (miRNAs) have emerged as biomarkers of metabolic status, etiological factors in complex disease, and promising drug targets. Recent reports suggest that miRNAs are critical regulators of pathways underlying the pathophysiology of type 2 diabetes. In this study, we demonstrate by deep sequencing and real-time quantitative PCR that hepatic levels of Foxa2 mRNA and miR-29 are elevated in a mouse model of diet-induced insulin resistance. We also show that Foxa2 and miR-29 are significantly upregulated in the livers of Zucker diabetic fatty (fa/fa) rats and that the levels of both returned to normal upon treatment with the insulin-sensitizing agent pioglitazone. We present evidence that miR-29 expression in human hepatoma cells is controlled in part by FOXA2, which is known to play a critical role in hepatic energy homeostasis. Moreover, we demonstrate that miR-29 fine-tunes FOXA2-mediated activation of key lipid metabolism genes, including PPARGC1A, HMGCS2, and ABHD5. These results suggest that miR-29 is an important regulatory factor in normal metabolism and may represent a novel therapeutic target in type 2 diabetes and related metabolic syndromes. PMID:24722248

  6. 3′-UTR engineering to improve soluble expression and fine-tuning of activity of cascade enzymes in Escherichia coli

    PubMed Central

    Song, Ji-Won; Woo, Ji-Min; Jung, Gyoo Yeol; Bornscheuer, Uwe T.; Park, Jin-Byung

    2016-01-01

    3′-Untranslated region (3′UTR) engineering was investigated to improve solubility of heterologous proteins (e.g., Baeyer-Villiger monooxygenases (BVMOs)) in Escherichia coli. Insertion of gene fragments containing putative RNase E recognition sites into the 3′UTR of the BVMO genes led to the reduction of mRNA levels in E. coli. Importantly, the amounts of soluble BVMOs were remarkably enhanced resulting in a proportional increase of in vivo catalytic activities. Notably, this increase in biocatalytic activity correlated to the number of putative RNase E endonucleolytic cleavage sites in the 3′UTR. For instance, the biotransformation activity of the BVMO BmoF1 (from Pseudomonas fluorescens DSM50106) in E. coli was linear to the number of RNase E cleavage sites in the 3′UTR. In summary, 3′UTR engineering can be used to improve the soluble expression of heterologous enzymes, thereby fine-tuning the enzyme activity in microbial cells. PMID:27406241

  7. Pore radius fine tuning of a silica matrix (MCM-41) based on the synthesis of alumina nanolayers with different thicknesses by atomic layer deposition

    SciTech Connect

    Zemtsova, Elena G. Arbenin, Andrei Yu.; Plotnikov, Alexander F.; Smirnov, Vladimir M.

    2015-03-15

    The authors investigated a new approach to modify the surface of the mesoporous silica matrix MCM-41. This approach is based on manipulating the chemical composition of the porous surface layer and also on fine tuning the pore radius by applying the atomic layer deposition (ALD) technique. The synthesis of alumina nanolayers was performed on the planar and the porous matrix (MCM-41) by the ALD technique using aluminum tri-sec-butoxide and water as precursors. The authors show that one cycle on silicon, using aluminum tri-sec-butoxide and water as precursors, results in a 1–1.2 Å increase in alumina nanolayer thickness. This is comparable to the increase in thickness per cycle for other precursors such as trimethylaluminum and aluminum chloride. The authors show that the synthesis of an Al{sub 2}O{sub 3} nanolayer on the pore surface of the mesoporous silica matrix MCM-41 by the ALD technique results in a regular change in the porous structure of the samples. The specific porosity (ml/g) of the MCM-41 was 0.95 and that of MCM-41 after 5 ALD cycles was 0.39. The pore diameter (nm) of MCM-41 was 3.3 and that of MCM-41 after 5 ALD cycles was 2.3.

  8. MicroRNA-29 fine-tunes the expression of key FOXA2-activated lipid metabolism genes and is dysregulated in animal models of insulin resistance and diabetes.

    PubMed

    Kurtz, C Lisa; Peck, Bailey C E; Fannin, Emily E; Beysen, Carine; Miao, Ji; Landstreet, Stuart R; Ding, Shengli; Turaga, Vandana; Lund, P Kay; Turner, Scott; Biddinger, Sudha B; Vickers, Kasey C; Sethupathy, Praveen

    2014-09-01

    MicroRNAs (miRNAs) have emerged as biomarkers of metabolic status, etiological factors in complex disease, and promising drug targets. Recent reports suggest that miRNAs are critical regulators of pathways underlying the pathophysiology of type 2 diabetes. In this study, we demonstrate by deep sequencing and real-time quantitative PCR that hepatic levels of Foxa2 mRNA and miR-29 are elevated in a mouse model of diet-induced insulin resistance. We also show that Foxa2 and miR-29 are significantly upregulated in the livers of Zucker diabetic fatty (fa/fa) rats and that the levels of both returned to normal upon treatment with the insulin-sensitizing agent pioglitazone. We present evidence that miR-29 expression in human hepatoma cells is controlled in part by FOXA2, which is known to play a critical role in hepatic energy homeostasis. Moreover, we demonstrate that miR-29 fine-tunes FOXA2-mediated activation of key lipid metabolism genes, including PPARGC1A, HMGCS2, and ABHD5. These results suggest that miR-29 is an important regulatory factor in normal metabolism and may represent a novel therapeutic target in type 2 diabetes and related metabolic syndromes.

  9. The Catalytic and Non-catalytic Functions of the Brahma Chromatin-Remodeling Protein Collaborate to Fine-Tune Circadian Transcription in Drosophila

    PubMed Central

    Kwok, Rosanna S.; Li, Ying H.; Lei, Anna J.; Edery, Isaac; Chiu, Joanna C.

    2015-01-01

    Daily rhythms in gene expression play a critical role in the progression of circadian clocks, and are under regulation by transcription factor binding, histone modifications, RNA polymerase II (RNAPII) recruitment and elongation, and post-transcriptional mechanisms. Although previous studies have shown that clock-controlled genes exhibit rhythmic chromatin modifications, less is known about the functions performed by chromatin remodelers in animal clockwork. Here we have identified the Brahma (Brm) complex as a regulator of the Drosophila clock. In Drosophila, CLOCK (CLK) is the master transcriptional activator driving cyclical gene expression by participating in an auto-inhibitory feedback loop that involves stimulating the expression of the main negative regulators, period (per) and timeless (tim). BRM functions catalytically to increase nucleosome density at the promoters of per and tim, creating an overall restrictive chromatin landscape to limit transcriptional output during the active phase of cycling gene expression. In addition, the non-catalytic function of BRM regulates the level and binding of CLK to target promoters and maintains transient RNAPII stalling at the per promoter, likely by recruiting repressive and pausing factors. By disentangling its catalytic versus non-catalytic functions at the promoters of CLK target genes, we uncovered a multi-leveled mechanism in which BRM fine-tunes circadian transcription. PMID:26132408

  10. Direct flow cytometry measurements reveal a fine-tuning of symbiotic cell dynamics according to the host developmental needs in aphid symbiosis

    PubMed Central

    Simonet, Pierre; Duport, Gabrielle; Gaget, Karen; Weiss-Gayet, Michèle; Colella, Stefano; Febvay, Gérard; Charles, Hubert; Viñuelas, José; Heddi, Abdelaziz; Calevro, Federica

    2016-01-01

    Endosymbiotic associations constitute a driving force in the ecological and evolutionary diversification of metazoan organisms. Little is known about whether and how symbiotic cells are coordinated according to host physiology. Here, we use the nutritional symbiosis between the insect pest, Acyrthosiphon pisum, and its obligate symbiont, Buchnera aphidicola, as a model system. We have developed a novel approach for unculturable bacteria, based on flow cytometry, and used this method to estimate the absolute numbers of symbionts at key stages of aphid life. The endosymbiont population increases exponentially throughout nymphal development, showing a growing rate which has never been characterized by indirect molecular techniques. Using histology and imaging techniques, we have shown that the endosymbiont-bearing cells (bacteriocytes) increase significantly in number and size during the nymphal development, and clustering in the insect abdomen. Once adulthood is reached and the laying period has begun, the dynamics of symbiont and host cells is reversed: the number of endosymbionts decreases progressively and the bacteriocyte structure degenerates during insect aging. In summary, these results show a coordination of the cellular dynamics between bacteriocytes and primary symbionts and reveal a fine-tuning of aphid symbiotic cells to the nutritional demand imposed by the host physiology throughout development. PMID:26822159

  11. Sox2 in the dermal papilla niche controls hair growth by fine-tuning BMP signaling in differentiating hair shaft progenitors.

    PubMed

    Clavel, Carlos; Grisanti, Laura; Zemla, Roland; Rezza, Amelie; Barros, Rita; Sennett, Rachel; Mazloom, Amin Reza; Chung, Chi-Yeh; Cai, Xiaoqiang; Cai, Chen-Leng; Pevny, Larysa; Nicolis, Silvia; Ma'ayan, Avi; Rendl, Michael

    2012-11-13

    How dermal papilla (DP) niche cells regulate hair follicle progenitors to control hair growth remains unclear. Using Tbx18(Cre) to target embryonic DP precursors, we ablate the transcription factor Sox2 early and efficiently, resulting in diminished hair shaft outgrowth. We find that DP niche expression of Sox2 controls the migration speed of differentiating hair shaft progenitors. Transcriptional profiling of Sox2 null DPs reveals increased Bmp6 and decreased BMP inhibitor Sostdc1, a direct Sox2 transcriptional target. Subsequently, we identify upregulated BMP signaling in knockout hair shaft progenitors and demonstrate that Bmp6 inhibits cell migration, an effect that can be attenuated by Sostdc1. A shorter and Sox2-negative hair type lacks Sostdc1 in the DP and shows reduced migration and increased BMP activity of hair shaft progenitors. Collectively, our data identify Sox2 as a key regulator of hair growth that controls progenitor migration by fine-tuning BMP-mediated mesenchymal-epithelial crosstalk.

  12. A general and high yielding fragment coupling synthesis of heteroatom-bridged calixarenes and the unprecedented examples of calixarene cavity fine-tuned by bridging heteroatoms.

    PubMed

    Wang, Mei-Xiang; Yang, Hai-Bo

    2004-12-01

    A number of aza- and/or oxo-bridged calix[2]arene[2]triazines have been synthesized through an unusually high yielding and efficient fragment coupling approach starting from cyanuric chloride and resorcinol, 3-aminophenol, m-phenylenediamine, and N,N'-dimethyl-m-phenylenediamine. These novel macrocycles, which belong to the next generation of calixarenes or cyclophanes, form a unique cavity that is resulted from two isolated benzene planes and two bis-heteroatom-conjugated triazine planes in a 1,3-alternate fashion. The nature of the bridging heteroatoms, i.e., combination of the electronic, conjugative, and steric effects of the nitrogen and oxygen atoms, strongly regulates the cavity size, generating a set of fine-tuned cavities in which the distance between two benzene rings at the upper rim ranges from 5.011 to 7.979 A. The multiple intermolecular hydrogen bond interactions among N,N'-dimethylated tetraazacalix[2]arene[2]triazines and among tetraazacalix[2]arene[2]triazines lead to the formation of infinite one-dimensional chain structure and two-dimensional zigzag layered structure, respectively, in the solid state. The ease of preparation and further chemical manipulations, and the readily tunable cavity structures render these aza- and/or oxo-bridged calix[2]arene[2]triazines the unique platforms in the study of supramolecular chemistry.

  13. Listeria monocytogenes CadC regulates cadmium efflux and fine-tunes lipoprotein localization to escape the host immune response and promote infection.

    PubMed

    Pombinho, Rita; Camejo, Ana; Vieira, Ana; Reis, Olga; Carvalho, Filipe; Almeida, Maria Teresa; Pinheiro, Jorge Campos; Sousa, Sandra; Cabanes, Didier

    2017-03-09

    Listeria monocytogenes (Lm) is a major intracellular human foodborne bacterial pathogen. We previously revealed Lm-cadC as highly expressed during mouse infection. Here we show that Lm-CadC is a sequence-specific, DNA-binding and cadmium-dependent regulator of CadA, an efflux pump conferring cadmium resistance. CadC, but not CadA, is required for Lm infection in vivo. Interestingly, CadC also directly represses lspB, a gene encoding a lipoprotein signal peptidase whose expression appears detrimental for infection. lspB overexpression promotes the release of the LpeA lipoprotein to the extracellular medium, inducing TNF- and IL-6 expression, thus impairing Lm survival in macrophages. We propose that Lm uses CadC to repress lspB expression during infection to avoid LpeA exposure to the host immune system, diminishing inflammatory cytokine expression and promoting intramacrophage survival and virulence. CadC appears as the first metal efflux pump regulator repurposed during infection to fine-tune lipoprotein processing and host responses.

  14. High energy, widely tunable Si-prism-array coupled terahertz-wave parametric oscillator with a deformed pump and optimal crystal location for angle tuning.

    PubMed

    Zhang, Ruiliang; Qu, Yanchen; Zhao, Weijiang; Chen, Zhenlei

    2017-03-20

    A high energy, widely tunable Si-prism-array coupled terahertz-wave parametric oscillator (TPO) has been demonstrated by using a deformed pump. The deformed pump is cut from a beam spot of 2 mm in diameter by a 1-mm-wide slit. In comparison with a small pump spot (1-mm diameter), the THz-wave coupling area for the deformed pump is increased without limitation to the low-frequency end of the tuning range. Besides, the crystal location is specially designed to eliminate the alteration of the output position of the pump during angle tuning, so the initially adjusted nearest pumped region to the THz-wave exit surface is maintained throughout the tuning range. The tuning range is 0.58-2.5 THz for the deformed pump, while its low frequency end is limited at approximately 1.2 THz for the undeformed pump with 2 mm diameter. The highest THz-wave output of 2 μJ, which is 2.25 times as large as that from the pump of 1 mm in diameter, is obtained at 1.15 THz under 38 mJ (300  MW/cm2) pumping. The energy conversion efficiency is 5.3×10-5.

  15. Multibeam Phased Array Antennas

    NASA Technical Reports Server (NTRS)

    Popovic, Zoya; Romisch, Stefania; Rondineau, Sebastien

    2004-01-01

    In this study, a new architecture for Ka-band multi-beam arrays was developed and demonstrated experimentally. The goal of the investigation was to demonstrate a new architecture that has the potential of reducing the cost as compared to standard expensive phased array technology. The goals of this specific part of the project, as stated in the yearly statement of work in the original proposal are: 1. Investigate bounds on performance of multi-beam lens arrays in terms of beamwidths, volume (size), isolation between beams, number of simultaneous beams, etc. 2. Design a small-scale array to demonstrate the principle. The array will be designed for operation around 3OGHz (Ka-band), with two 10-degree beamwidth beams. 3. Investigate most appropriate way to accomplish fine-tuning of the beam pointing within 5 degrees around the main beam pointing angle.

  16. The fine structure of microseisms: observations from a three-component array in Central France

    NASA Astrophysics Data System (ADS)

    Riahi, N.; Saenger, E. H.

    2012-12-01

    We study the wave type composition and directionality of microseisms in the frequency range 0.1 to 1.1 Hz using data from a temporary three-component seismic array in Central France. The data were acquired in April and November 2010 during four and eight days, respectively. Two seasonal snapshots of the ambient seismic wave field are thus available for a location in the vicinity of several large water bodies (North Sea, Atlantic Sea, and Mediterranean Sea). Fourier-domain beam-forming is applied simultaneously on all components to jointly estimate propagation (back azimuth, phase velocity) and polarization features as a function of frequency. We find that the relative contribution of Rayleigh and Love wave modes strongly varies by frequency as well as back azimuth. Body waves with narrow back azimuth ranges are also observed, in particular around the secondary microseism peak (P waves from the North Sea) and around 0.7 Hz (SV waves with back azimuth NNW). Interestingly, the observed wave field composition and directionality does not differ much between the April and November snapshots, although seismic power is about 10 dB higher in November. Implications of these results for microseism source studies and interferometry are discussed.

  17. Dynamically tuning emission band of CdSe/ZnS quantum dots assembled on Ag nanorod array: plasmon-enhanced Stark shift.

    PubMed

    Peng, Xiao-Niu; Zhou, Zhang-Kai; Zhang, Wei; Hao, Zhong-Hua

    2011-11-21

    We demonstrate tuning emission band of CdSe/ZnS semiconductor quantum dots (SQDs) closely-packed in the proximity of Ag nanorod array by dynamically adjusting exciton-plasmon interaction. Large red-shift is observed in two-photon luminescence (TPL) spectra of the SQDs when the longitudinal surface plasmon resonance (LSPR) of Ag nanorod array is adjusted to close to excitation laser wavelength, and the spectral red-shift of TPL reaches as large as 101 meV by increasing excitation power, which is slightly larger than full width at half-maximum of emission spectrum of the SQDs. The observed LSPR-dependent spectral shifting behaviors are explained by a theoretical model of plasmon-enhanced quantum-confined Stark effect. These observations could find the applications in dynamical information processing in active plasmonic and photonic nanodevices.

  18. Fine-tuning Philippine transactions

    SciTech Connect

    Vitale, R.

    1994-11-01

    Expanding the power generation and distribution capability of the Philippines remains a top priority of the Philippine government. It is therefore not surprising that a number of the most significant legislative initiatives approved by the Philippine legislature in the past few years have been designed to encourage these activities in particular. There are several recent, significant statutes that will affect both power and non-power projects undertaken in the Philippines.

  19. Fine-Tuning Teacher Evaluation

    ERIC Educational Resources Information Center

    Marshall, Kim

    2012-01-01

    As many states and districts rethink teacher supervision and evaluation, the team at the Measures of Effective Teaching (MET) Project, funded by the Bill and Melinda Gates Foundation, has analyzed thousands of lesson videotapes and studied the shortcomings of current practices. The tentative conclusion: Teachers should be evaluated on three…

  20. The weak, fine-tuned binding of ubiquitous transcription factors to the Il-2 enhancer contributes to its T cell-restricted activity.

    PubMed Central

    Hentsch, B; Mouzaki, A; Pfeuffer, I; Rungger, D; Serfling, E

    1992-01-01

    The T lymphocyte-specific enhancers of the murine and human Interleukin 2 (Il-2) genes harbour several binding sites for ubiquitous transcription factors. All these sites for the binding of AP-1, NF-kB or Oct-1 are non-canonical sites, i.e. they differ in one or a few base pairs from consensus sequences for the optimal binding of these factors. Although the factors bind weakly to these sites, the latter are functionally important because their mutation to non-binding sites results in a decrease of inducible activity of the Il-2 enhancer. Conversion of three sites to canonical binding sites of Octamer factors, AP-1 and NF-kB results in a drastic increase in enhancer activity and the induction of the Il-2 enhancer in non-T cells, such as B cell lines, murine L cells and human HeLa cells. The introduction of two or three canonical sites into the enhancer leads to a further increase of its activity. Il-2 enhancer induction is also observed in B cells when the concentration of AP-1 and Oct factors increases as a result of cotransfections with FosB and Octamer expression plasmids. When Il-2 enhancer constructs carrying canonical factor binding sites were injected into Xenopus oocytes the strong binding of ubiquitous factors substantially overcomes the silencing effect of negatively acting factors present in resting primary T lymphocytes. These results suggest a fine-tuned interplay between ubiquitous and lymphoid-specific factors binding to and transactivating the Il-2 enhancer and show that the binding affinity of ubiquitous factors to the enhancer contributes to its cell-type specific activity. Moreover, we believe that a dramatic increase of transcriptional activity brought about by single point mutations at strategic important factor binding sites may also have relevance to the activation of nuclear oncogenes. Images PMID:1614851

  1. Fine Tuning of CaV1.3 Ca2+ channel properties in adult inner hair cells positioned in the most sensitive region of the Gerbil Cochlea.

    PubMed

    Zampini, Valeria; Johnson, Stuart L; Franz, Christoph; Knipper, Marlies; Holley, Matthew C; Magistretti, Jacopo; Russo, Giancarlo; Marcotti, Walter; Masetto, Sergio

    2014-01-01

    Hearing relies on faithful signal transmission by cochlear inner hair cells (IHCs) onto auditory fibres over a wide frequency and intensity range. Exocytosis at IHC ribbon synapses is triggered by Ca(2+) inflow through Ca(V)1.3 (L-type) Ca(2+) channels. We investigated the macroscopic (whole-cell) and elementary (cell-attached) properties of Ca(2+) currents in IHCs positioned at the middle turn (frequency ∼ 2 kHz) of the adult gerbil cochlea, which is their most sensitive hearing region. Using near physiological recordings conditions (body temperature and a Na(+) based extracellular solution), we found that the macroscopic Ca(2+) current activates and deactivates very rapidly (time constant below 1 ms) and inactivates slowly and only partially. Single-channel recordings showed an elementary conductance of 15 pS, a sub-ms latency to first opening, and a very low steady-state open probability (Po: 0.024 in response to 500-ms depolarizing steps at ∼-18 mV). The value of Po was significantly larger (0.06) in the first 40 ms of membrane depolarization, which corresponds to the time when most Ca(2+) channel openings occurred clustered in bursts (mean burst duration: 19 ms). Both the Po and the mean burst duration were smaller than those previously reported in high-frequency basal IHCs. Finally, we found that middle turn IHCs are likely to express about 4 times more Ca(2+) channels per ribbon than basal cells. We propose that middle-turn IHCs finely-tune Ca(V)1.3 Ca(2+) channel gating in order to provide reliable information upon timing and intensity of lower-frequency sounds.

  2. Fine-tuning of histone H3 Lys4 methylation during pseudohyphal differentiation by the CDK submodule of RNA polymerase II.

    PubMed

    Law, Michael J; Ciccaglione, Kerri

    2015-02-01

    Transcriptional regulation is dependent upon the interactions between the RNA pol II holoenzyme complex and chromatin. RNA pol II is part of a highly conserved multiprotein complex that includes the core mediator and CDK8 subcomplex. In Saccharomyces cerevisiae, the CDK8 subcomplex, composed of Ssn2p, Ssn3p, Ssn8p, and Srb8p, is thought to play important roles in mediating transcriptional control of stress-responsive genes. Also central to transcriptional control are histone post-translational modifications. Lysine methylation, dynamically balanced by lysine methyltransferases and demethylases, has been intensively studied, uncovering significant functions in transcriptional control. A key question remains in understanding how these enzymes are targeted during stress response. To determine the relationship between lysine methylation, the CDK8 complex, and transcriptional control, we performed phenotype analyses of yeast lacking known lysine methyltransferases or demethylases in isolation or in tandem with SSN8 deletions. We show that the RNA pol II CDK8 submodule components SSN8/SSN3 and the histone demethylase JHD2 are required to inhibit pseudohyphal growth-a differentiation pathway induced during nutrient limitation-under rich conditions. Yeast lacking both SSN8 and JHD2 constitutively express FLO11, a major regulator of pseudohyphal growth. Interestingly, deleting known FLO11 activators including FLO8, MSS11, MFG1, TEC1, SNF1, KSS1, and GCN4 results in a range of phenotypic suppression. Using chromatin immunoprecipitation, we found that SSN8 inhibits H3 Lys4 trimethylation independently of JHD2 at the FLO11 locus, suggesting that H3 Lys4 hypermethylation is locking FLO11 into a transcriptionally active state. These studies implicate the CDK8 subcomplex in fine-tuning H3 Lys4 methylation levels during pseudohyphal differentiation. Copyright © 2015 by the Genetics Society of America.

  3. In response to partial plant shading, the lack of phytochrome A does not directly induce leaf senescence but alters the fine-tuning of chlorophyll biosynthesis.

    PubMed

    Brouwer, Bastiaan; Gardeström, Per; Keech, Olivier

    2014-07-01

    Phytochrome is thought to control the induction of leaf senescence directly, however, the signalling and molecular mechanisms remain unclear. In the present study, an ecophysiological approach was used to establish a functional connection between phytochrome signalling and the physiological processes underlying the induction of leaf senescence in response to shade. With shade it is important to distinguish between complete and partial shading, during which either the whole or only a part of the plant is shaded, respectively. It is first shown here that, while PHYB is required to maintain chlorophyll content in a completely shaded plant, only PHYA is involved in maintaining the leaf chlorophyll content in response to partial plant shading. Second, it is shown that leaf yellowing associated with strong partial shading in phyA-mutant plants actually correlates to a decreased biosynthesis of chlorophyll rather than to an increase of its degradation. Third, it is shown that the physiological impact of this decreased biosynthesis of chlorophyll in strongly shaded phyA-mutant leaves is accompanied by a decreased capacity to adjust the Light Compensation Point. However, the increased leaf yellowing in phyA-mutant plants is not accompanied by an increase of senescence-specific molecular markers, which argues against a direct role of PHYA in inducing leaf senescence in response to partial shade. In conclusion, it is proposed that PHYA, but not PHYB, is essential for fine-tuning the chlorophyll biosynthetic pathway in response to partial shading. In turn, this mechanism allows the shaded leaf to adjust its photosynthetic machinery to very low irradiances, thus maintaining a positive carbon balance and repressing the induction of leaf senescence, which can occur under prolonged periods of shade. © The Author 2014. Published by Oxford University Press on behalf of the Society for Experimental Biology.

  4. Enhancing signal to noise ratio by fine-tuning tapers of cladded/uncladded buffer rods in ultrasonic time domain reflectometry in smelters.

    PubMed

    Viumdal, Håkon; Mylvaganam, Saba

    2014-03-01

    Buffer rods (BR) as waveguides in ultrasonic time domain reflectometry (TDR) can somewhat extend the range of industrial applications of ultrasonics. Level, temperature and flow measurements involving elevated temperatures, corrosive fluids and generally harsh environments are some of the applications in which conventional ultrasonic transducers cannot be used directly in contact with the media. In such cases, BRs with some design modifications can make ultrasonic TDR measurements possible with limited success. This paper deals with TDR in conjunction with distance measurements in extremely hot fluids, using conventional ultrasonic transducers in combination with BRs. When using BRs in the ultrasonic measurement systems in extreme temperatures, problems associated with size and the material of the buffer, have to be addressed. The resonant frequency of the transducer and the relative size of the transducer with respect to the diameter of BR are also important parameters influencing the signal to noise ratio (SNR) of the signal processing system used in the ultrasonic TDR. This paper gives an overview of design aspects related to the BRs with special emphasis on tapers and cladding used on BRs. As protective cladding, zirconium oxide-yttrium oxide composite was used, with its proven thermal stability in withstanding temperatures in rocket and jet engines up to 1650 °C. In general a BR should guide the signals through to the medium and from and back to the transducer without excessive attenuation and at the same time not exacerbate the noise in the measurement system. The SNR is the decisive performance indicator to consider in the design of BR based ultrasonic TDR, along with appropriate transducer, with suitable size and operating frequency. This work presents and analyses results from extensive experiments related to fine-tuning both geometry of and signals in cladded/uncladded BRs used in high temperature ultrasonic TDR with focus on overall performance based on

  5. Arabidopsis AtHB7 and AtHB12 evolved divergently to fine tune processes associated with growth and responses to water stress.

    PubMed

    Ré, Delfina A; Capella, Matías; Bonaventure, Gustavo; Chan, Raquel L

    2014-05-31

    Arabidopsis AtHB7 and AtHB12 transcription factors (TFs) belong to the homeodomain-leucine zipper subfamily I (HD-Zip I) and present 62% amino acid identity. These TFs have been associated with the control of plant development and abiotic stress responses; however, at present it is not completely understood how AtHB7 and AtHB12 regulate these processes. By using different expression analysis approaches, we found that AtHB12 is expressed at higher levels during early Arabidopsis thaliana development whereas AtHB7 during later developmental stages. Moreover, by analysing gene expression in single and double Arabidopsis mutants and in transgenic plants ectopically expressing these TFs, we discovered a complex mechanism dependent on the plant developmental stage and in which AtHB7 and AtHB12 affect the expression of each other. Phenotypic analysis of transgenic plants revealed that AtHB12 induces root elongation and leaf development in young plants under standard growth conditions, and seed production in water-stressed plants. In contrast, AtHB7 promotes leaf development, chlorophyll levels and photosynthesis and reduces stomatal conductance in mature plants. Moreover AtHB7 delays senescence processes in standard growth conditions. We demonstrate that AtHB7 and AtHB12 have overlapping yet specific roles in several processes related to development and water stress responses. The analysis of mutant and transgenic plants indicated that the expression of AtHB7 and AtHB12 is regulated in a coordinated manner, depending on the plant developmental stage and the environmental conditions. The results suggested that AtHB7 and AtHB12 evolved divergently to fine tune processes associated with development and responses to mild water stress.

  6. In response to partial plant shading, the lack of phytochrome A does not directly induce leaf senescence but alters the fine-tuning of chlorophyll biosynthesis

    PubMed Central

    Brouwer, Bastiaan; Gardeström, Per; Keech, Olivier

    2014-01-01

    Phytochrome is thought to control the induction of leaf senescence directly, however, the signalling and molecular mechanisms remain unclear. In the present study, an ecophysiological approach was used to establish a functional connection between phytochrome signalling and the physiological processes underlying the induction of leaf senescence in response to shade. With shade it is important to distinguish between complete and partial shading, during which either the whole or only a part of the plant is shaded, respectively. It is first shown here that, while PHYB is required to maintain chlorophyll content in a completely shaded plant, only PHYA is involved in maintaining the leaf chlorophyll content in response to partial plant shading. Second, it is shown that leaf yellowing associated with strong partial shading in phyA-mutant plants actually correlates to a decreased biosynthesis of chlorophyll rather than to an increase of its degradation. Third, it is shown that the physiological impact of this decreased biosynthesis of chlorophyll in strongly shaded phyA-mutant leaves is accompanied by a decreased capacity to adjust the Light Compensation Point. However, the increased leaf yellowing in phyA-mutant plants is not accompanied by an increase of senescence-specific molecular markers, which argues against a direct role of PHYA in inducing leaf senescence in response to partial shade. In conclusion, it is proposed that PHYA, but not PHYB, is essential for fine-tuning the chlorophyll biosynthetic pathway in response to partial shading. In turn, this mechanism allows the shaded leaf to adjust its photosynthetic machinery to very low irradiances, thus maintaining a positive carbon balance and repressing the induction of leaf senescence, which can occur under prolonged periods of shade. PMID:24604733

  7. Arabidopsis AtHB7 and AtHB12 evolved divergently to fine tune processes associated with growth and responses to water stress

    PubMed Central

    2014-01-01

    Background Arabidopsis AtHB7 and AtHB12 transcription factors (TFs) belong to the homeodomain-leucine zipper subfamily I (HD-Zip I) and present 62% amino acid identity. These TFs have been associated with the control of plant development and abiotic stress responses; however, at present it is not completely understood how AtHB7 and AtHB12 regulate these processes. Results By using different expression analysis approaches, we found that AtHB12 is expressed at higher levels during early Arabidopsis thaliana development whereas AtHB7 during later developmental stages. Moreover, by analysing gene expression in single and double Arabidopsis mutants and in transgenic plants ectopically expressing these TFs, we discovered a complex mechanism dependent on the plant developmental stage and in which AtHB7 and AtHB12 affect the expression of each other. Phenotypic analysis of transgenic plants revealed that AtHB12 induces root elongation and leaf development in young plants under standard growth conditions, and seed production in water-stressed plants. In contrast, AtHB7 promotes leaf development, chlorophyll levels and photosynthesis and reduces stomatal conductance in mature plants. Moreover AtHB7 delays senescence processes in standard growth conditions. Conclusions We demonstrate that AtHB7 and AtHB12 have overlapping yet specific roles in several processes related to development and water stress responses. The analysis of mutant and transgenic plants indicated that the expression of AtHB7 and AtHB12 is regulated in a coordinated manner, depending on the plant developmental stage and the environmental conditions. The results suggested that AtHB7 and AtHB12 evolved divergently to fine tune processes associated with development and responses to mild water stress. PMID:24884528

  8. Fine Tuning of CaV1.3 Ca2+ Channel Properties in Adult Inner Hair Cells Positioned in the Most Sensitive Region of the Gerbil Cochlea

    PubMed Central

    Zampini, Valeria; Johnson, Stuart L.; Franz, Christoph; Knipper, Marlies; Holley, Matthew C.; Magistretti, Jacopo; Russo, Giancarlo; Marcotti, Walter; Masetto, Sergio

    2014-01-01

    Hearing relies on faithful signal transmission by cochlear inner hair cells (IHCs) onto auditory fibres over a wide frequency and intensity range. Exocytosis at IHC ribbon synapses is triggered by Ca2+ inflow through CaV1.3 (L-type) Ca2+ channels. We investigated the macroscopic (whole-cell) and elementary (cell-attached) properties of Ca2+ currents in IHCs positioned at the middle turn (frequency ∼2 kHz) of the adult gerbil cochlea, which is their most sensitive hearing region. Using near physiological recordings conditions (body temperature and a Na+ based extracellular solution), we found that the macroscopic Ca2+ current activates and deactivates very rapidly (time constant below 1 ms) and inactivates slowly and only partially. Single-channel recordings showed an elementary conductance of 15 pS, a sub-ms latency to first opening, and a very low steady-state open probability (Po: 0.024 in response to 500-ms depolarizing steps at ∼−18 mV). The value of Po was significantly larger (0.06) in the first 40 ms of membrane depolarization, which corresponds to the time when most Ca2+ channel openings occurred clustered in bursts (mean burst duration: 19 ms). Both the Po and the mean burst duration were smaller than those previously reported in high-frequency basal IHCs. Finally, we found that middle turn IHCs are likely to express about 4 times more Ca2+ channels per ribbon than basal cells. We propose that middle-turn IHCs finely-tune CaV1.3 Ca2+ channel gating in order to provide reliable information upon timing and intensity of lower-frequency sounds. PMID:25409445

  9. MicroRNA-15a fine-tunes the level of Delta-like 1 homolog (DLK1) in proliferating 3T3-L1 preadipocytes

    SciTech Connect

    Andersen, Ditte C.; Schneider, Mikael; Eskildsen, Tilde; Teisner, Borge; and others

    2010-06-10

    Delta like 1 homolog (Dlk1) exists in both transmembrane and soluble molecular forms, and is implicated in cellular growth and plays multiple roles in development, tissue regeneration, and cancer. Thus, DLK1 levels are critical for cell function, and abnormal DLK1 expression can be lethal; however, little is known about the underlying mechanisms. We here report that miR-15a modulates DLK1 levels in preadipocytes thus providing a mechanism for DLK1 regulation that further links it to cell cycle arrest and cancer since miR-15a is deregulated in these processes. In preadipocytes, miR-15a increases with cell density, and peaks at the same stage where membrane DLK1{sup M} and soluble DLK1{sup S} are found at maximum levels. Remarkably, miR-15a represses the amount of all Dlk1 variants at the mRNA level but also the level of DLK1{sup M} protein while it increases the amount of DLK1{sup S} supporting a direct repression of DLK1 and a parallel effect on the protease that cleaves off the DLK1 from the membrane. In agreement with previous studies, we found that miR-15a represses cell numbers, but additionally, we report that miR-15a also increases cell size. Conversely, anti-miR-15a treatment decreases cell size while increasing cell numbers, scenarios that were completely rescued by addition of purified DLK1{sup S}. Our data thus imply that miR-15a regulates cell size and proliferation by fine-tuning Dlk1 among others, and further emphasize miR-15a and DLK1 levels to play important roles in growth signaling networks.

  10. Surface charge fine tuning of reversed-phase/weak anion-exchange type mixed-mode stationary phases for milder elution conditions.

    PubMed

    Zimmermann, Aleksandra; Horak, Jeannie; Sánchez-Muñoz, Orlando L; Lämmerhofer, Michael

    2015-08-28

    A series of new mixed-mode reversed-phase/weak anion-exchange (RP/WAX) phases have been synthesized by immobilization of N-undecenyl-3-α-aminotropane onto thiol-modified silica gel by thiol-ene click chemistry and subsequent introduction of acidic thiol-endcapping functionalities of different type and surface densities. Click chemistry allowed to adjust a controlled surface concentration of the RP/WAX ligand in such a way that a sufficient quantity of residual thiols remained unmodified which have been capped by thiol click with either 3-butenoic acid or allylsulfonic acid as co-ligands. In another embodiment, performic acid oxidation of N-undecenyl-3-α-aminotropane-derivatized thiol-modified silica gave a RP/WAX phase with high density of sulfonic acid end-capping groups. ζ-Potential determinations confirmed the fine-tuned pI of these mixed-mode stationary phases which was shifted from 9.5 to 8.2, 7.8, and 6.5 with 3-butenoic acid and allylsulfonic acid end-capping as well as performic acid oxidation. For acidic solutes, the co-ionic endcapping leads to strongly reduced retention times and clearly allowed elution of these analytes under lower ionic strength thus milder elution conditions. In spite of the acidic endcapping, the new mixed-mode phases maintained their hydrophobic and anion-exchange selectivity as well as their multimodal nature featuring RP and HILIC elution domains at acetonitrile percentages below and above 50%, respectively. Column classification by principal component analysis of an extended retention map in comparison to a set of polar commercial and in-house synthesized stationary phases confirmed complementarity of the new mixed-mode phases with respect to HILIC, polar RP, amino and commercial mixed-mode phases.

  11. Inadequate fine-tuning of protein synthesis and failure of amino acid homeostasis following inhibition of the ATPase VCP/p97

    PubMed Central

    Parzych, K; Chinn, T M; Chen, Z; Loaiza, S; Porsch, F; Valbuena, G N; Kleijnen, M F; Karadimitris, A; Gentleman, E; Keun, H C; Auner, H W

    2015-01-01

    The cellular mechanisms that control protein degradation may constitute a non-oncogenic cancer cell vulnerability and, therefore, a therapeutic target. Although this proposition is supported by the clinical success of proteasome inhibitors in some malignancies, most cancers are resistant to proteasome inhibition. The ATPase valosin-containing protein (VCP; p97) is an essential regulator of protein degradation in multiple pathways and has emerged as a target for cancer therapy. We found that pharmacological depletion of VCP enzymatic activity with mechanistically different inhibitors robustly induced proteotoxic stress in solid cancer and multiple myeloma cells, including cells that were insensitive, adapted, or clinically resistant to proteasome inhibition. VCP inhibition had an impact on two key regulators of protein synthesis, eukaryotic initiation factor 2α (eIF2α) and mechanistic target of rapamycin complex 1 (mTORC1), and attenuated global protein synthesis. However, a block on protein translation that was itself cytotoxic alleviated stress signaling and reduced cell death triggered by VCP inhibition. Some of the proteotoxic effects of VCP depletion depended on the eIF2α phosphatase, protein phosphatase 1 regulatory subunit 15A (PPP1R15A)/PP1c, but not on mTORC1, although there appeared to be cross-talk between them. Thus, cancer cell death following VCP inhibition was linked to inadequate fine-tuning of protein synthesis and activity of PPP1R15A/PP1c. VCP inhibitors also perturbed intracellular amino acid levels, activated eukaryotic translation initiation factor 2α kinase 4 (EIF2AK4), and enhanced cellular dependence on amino acid supplies, consistent with a failure of amino acid homeostasis. Many of the observed effects of VCP inhibition differed from the effects triggered by proteasome inhibition or by protein misfolding. Thus, depletion of VCP enzymatic activity triggers cancer cell death in part through inadequate regulation of protein synthesis and

  12. Modulation of the Substitution Pattern of 5-Aryl-2-Aminoimidazoles Allows Fine-Tuning of Their Antibiofilm Activity Spectrum and Toxicity

    PubMed Central

    Peeters, Elien; Hooyberghs, Geert; Robijns, Stijn; Waldrant, Kai; De Weerdt, Ami; Delattin, Nicolas; Liebens, Veerle; Kucharíková, Soňa; Tournu, Hélène; Verstraeten, Natalie; Dovgan, Barbara; Girandon, Lenart; Fröhlich, Mirjam; De Brucker, Katrijn; Michiels, Jan; Cammue, Bruno P. A.; Thevissen, Karin; Vanderleyden, Jozef; Van der Eycken, Erik

    2016-01-01

    We previously synthesized several series of compounds, based on the 5-aryl-2-aminoimidazole scaffold, that showed activity preventing the formation of Salmonella enterica serovar Typhimurium and Pseudomonas aeruginosa biofilms. Here, we further studied the activity spectrum of a number of the most active N1- and 2N-substituted 5-aryl-2-aminoimidazoles against a broad panel of biofilms formed by monospecies and mixed species of bacteria and fungi. An N1-substituted compound showed very strong activity against the biofilms formed by Gram-negative and Gram-positive bacteria and the fungus Candida albicans but was previously shown to be toxic against various eukaryotic cell lines. In contrast, 2N-substituted compounds were nontoxic and active against biofilms formed by Gram-negative bacteria and C. albicans but had reduced activity against biofilms formed by Gram-positive bacteria. In an attempt to develop nontoxic compounds with potent activity against biofilms formed by Gram-positive bacteria for application in antibiofilm coatings for medical implants, we synthesized novel compounds with substituents at both the N1 and 2N positions and tested these compounds for antibiofilm activity and toxicity. Interestingly, most of these N1-,2N-disubstituted 5-aryl-2-aminoimidazoles showed very strong activity against biofilms formed by Gram-positive bacteria and C. albicans in various setups with biofilms formed by monospecies and mixed species but lost activity against biofilms formed by Gram-negative bacteria. In light of application of these compounds as anti-infective coatings on orthopedic implants, toxicity against two bone cell lines and the functionality of these cells were tested. The N1-,2N-disubstituted 5-aryl-2-aminoimidazoles in general did not affect the viability of bone cells and even induced calcium deposition. This indicates that modulating the substitution pattern on positions N1 and 2N of the 5-aryl-2-aminoimidazole scaffold allows fine-tuning of both the

  13. Codon optimization of xylA gene for recombinant glucose isomerase production in Pichia pastoris and fed-batch feeding strategies to fine-tune bioreactor performance.

    PubMed

    Ata, Özge; Boy, Erdem; Güneş, Hande; Çalık, Pınar

    2015-05-01

    The objectives of this work are the optimization of the codons of xylA gene from Thermus thermophilus to enhance the production of recombinant glucose isomerase (rGI) in P. pastoris and to investigate the effects of feeding strategies on rGI production. Codons of xylA gene from T. thermophilus were optimized, ca. 30 % of the codons were replaced with those with higher frequencies according to the codon usage bias of P. pastoris, codon optimization resulted in a 2.4-fold higher rGI activity. To fine-tune bioreactor performance, fed-batch bioreactor feeding strategies were designed as continuous exponential methanol feeding with pre-calculated feeding rate based on the pre-determined specific growth rate, and fed-batch methanol-stat feeding. Six feeding strategies were designed, as follows: (S1) continuous exponential methanol- and pulse- sorbitol feeding; (S2) continuous exponential methanol- and peptone- feeding; (S3) continuous exponential methanol- and pulse- mannitol feeding; (S4) continuous exponential methanol- and peptone- feeding and pulse-mannitol feeding; (S5) methanol-stat feeding by keeping methanol concentration at 5 g L(-1); and, (S6) methanol-stat feeding by keeping methanol concentration at 5 g L(-1) and pulse-mannitol feeding. The highest cell and rGI activity was attained as 117 g L(-1) at t = 66 h and 32530 U L(-1) at t = 53 h, in strategy-S5. The use of the co-substrate mannitol does not increase the rGI activity in methanol-stat feeding, where 4.1-fold lower rGI activity was obtained in strategy-S6. The overall cell yield on total substrate was determined at t = 53 h as 0.21 g g(-1) in S5 strategy.

  14. Modulation of the Substitution Pattern of 5-Aryl-2-Aminoimidazoles Allows Fine-Tuning of Their Antibiofilm Activity Spectrum and Toxicity.

    PubMed

    Peeters, Elien; Hooyberghs, Geert; Robijns, Stijn; Waldrant, Kai; De Weerdt, Ami; Delattin, Nicolas; Liebens, Veerle; Kucharíková, Soňa; Tournu, Hélène; Verstraeten, Natalie; Dovgan, Barbara; Girandon, Lenart; Fröhlich, Mirjam; De Brucker, Katrijn; Van Dijck, Patrick; Michiels, Jan; Cammue, Bruno P A; Thevissen, Karin; Vanderleyden, Jozef; Van der Eycken, Erik; Steenackers, Hans P

    2016-11-01

    We previously synthesized several series of compounds, based on the 5-aryl-2-aminoimidazole scaffold, that showed activity preventing the formation of Salmonella enterica serovar Typhimurium and Pseudomonas aeruginosa biofilms. Here, we further studied the activity spectrum of a number of the most active N1- and 2N-substituted 5-aryl-2-aminoimidazoles against a broad panel of biofilms formed by monospecies and mixed species of bacteria and fungi. An N1-substituted compound showed very strong activity against the biofilms formed by Gram-negative and Gram-positive bacteria and the fungus Candida albicans but was previously shown to be toxic against various eukaryotic cell lines. In contrast, 2N-substituted compounds were nontoxic and active against biofilms formed by Gram-negative bacteria and C. albicans but had reduced activity against biofilms formed by Gram-positive bacteria. In an attempt to develop nontoxic compounds with potent activity against biofilms formed by Gram-positive bacteria for application in antibiofilm coatings for medical implants, we synthesized novel compounds with substituents at both the N1 and 2N positions and tested these compounds for antibiofilm activity and toxicity. Interestingly, most of these N1-,2N-disubstituted 5-aryl-2-aminoimidazoles showed very strong activity against biofilms formed by Gram-positive bacteria and C. albicans in various setups with biofilms formed by monospecies and mixed species but lost activity against biofilms formed by Gram-negative bacteria. In light of application of these compounds as anti-infective coatings on orthopedic implants, toxicity against two bone cell lines and the functionality of these cells were tested. The N1-,2N-disubstituted 5-aryl-2-aminoimidazoles in general did not affect the viability of bone cells and even induced calcium deposition. This indicates that modulating the substitution pattern on positions N1 and 2N of the 5-aryl-2-aminoimidazole scaffold allows fine-tuning of both the

  15. Inadequate fine-tuning of protein synthesis and failure of amino acid homeostasis following inhibition of the ATPase VCP/p97.

    PubMed

    Parzych, K; Chinn, T M; Chen, Z; Loaiza, S; Porsch, F; Valbuena, G N; Kleijnen, M F; Karadimitris, A; Gentleman, E; Keun, H C; Auner, H W

    2015-12-31

    The cellular mechanisms that control protein degradation may constitute a non-oncogenic cancer cell vulnerability and, therefore, a therapeutic target. Although this proposition is supported by the clinical success of proteasome inhibitors in some malignancies, most cancers are resistant to proteasome inhibition. The ATPase valosin-containing protein (VCP; p97) is an essential regulator of protein degradation in multiple pathways and has emerged as a target for cancer therapy. We found that pharmacological depletion of VCP enzymatic activity with mechanistically different inhibitors robustly induced proteotoxic stress in solid cancer and multiple myeloma cells, including cells that were insensitive, adapted, or clinically resistant to proteasome inhibition. VCP inhibition had an impact on two key regulators of protein synthesis, eukaryotic initiation factor 2α (eIF2α) and mechanistic target of rapamycin complex 1 (mTORC1), and attenuated global protein synthesis. However, a block on protein translation that was itself cytotoxic alleviated stress signaling and reduced cell death triggered by VCP inhibition. Some of the proteotoxic effects of VCP depletion depended on the eIF2α phosphatase, protein phosphatase 1 regulatory subunit 15A (PPP1R15A)/PP1c, but not on mTORC1, although there appeared to be cross-talk between them. Thus, cancer cell death following VCP inhibition was linked to inadequate fine-tuning of protein synthesis and activity of PPP1R15A/PP1c. VCP inhibitors also perturbed intracellular amino acid levels, activated eukaryotic translation initiation factor 2α kinase 4 (EIF2AK4), and enhanced cellular dependence on amino acid supplies, consistent with a failure of amino acid homeostasis. Many of the observed effects of VCP inhibition differed from the effects triggered by proteasome inhibition or by protein misfolding. Thus, depletion of VCP enzymatic activity triggers cancer cell death in part through inadequate regulation of protein synthesis and

  16. Functional Characterization of MODY2 Mutations Highlights the Importance of the Fine-Tuning of Glucokinase and Its Role in Glucose Sensing

    PubMed Central

    García-Herrero, Carmen-María; Rubio-Cabezas, Oscar; Azriel, Sharona; Gutierrez-Nogués, Angel; Aragonés, Angel; Vincent, Olivier; Campos-Barros, Angel; Argente, Jesús; Navas, María-Angeles

    2012-01-01

    Glucokinase (GK) acts as a glucose sensor in the pancreatic beta-cell and regulates insulin secretion. Heterozygous mutations in the human GK-encoding GCK gene that reduce the activity index increase the glucose-stimulated insulin secretion threshold and cause familial, mild fasting hyperglycaemia, also known as Maturity Onset Diabetes of the Young type 2 (MODY2). Here we describe the biochemical characterization of five missense GK mutations: p.Ile130Thr, p.Asp205His, p.Gly223Ser, p.His416Arg and p.Ala449Thr. The enzymatic analysis of the corresponding bacterially expressed GST-GK mutant proteins show that all of them impair the kinetic characteristics of the enzyme. In keeping with their position within the protein, mutations p.Ile130Thr, p.Asp205His, p.Gly223Ser, and p.His416Arg strongly decrease the activity index of GK, affecting to one or more kinetic parameters. In contrast, the p.Ala449Thr mutation, which is located in the allosteric activator site, does not affect significantly the activity index of GK, but dramatically modifies the main kinetic parameters responsible for the function of this enzyme as a glucose sensor. The reduced Kcat of the mutant (3.21±0.28 s−1 vs 47.86±2.78 s−1) is balanced by an increased glucose affinity (S0.5 = 1.33±0.08 mM vs 7.86±0.09 mM) and loss of cooperativity for this substrate. We further studied the mechanism by which this mutation impaired GK kinetics by measuring the differential effects of several competitive inhibitors and one allosteric activator on the mutant protein. Our results suggest that this mutation alters the equilibrium between the conformational states of glucokinase and highlights the importance of the fine-tuning of GK and its role in glucose sensing. PMID:22291974

  17. Gene expression analyses in tomato near isogenic lines provide evidence for ethylene and abscisic acid biosynthesis fine-tuning during arbuscular mycorrhiza development.

    PubMed

    Fracetto, Giselle Gomes Monteiro; Peres, Lázaro Eustáquio Pereira; Lambais, Marcio Rodrigues

    2017-07-01

    colonization in tomato roots, indicating that, besides hormonal interactions, a fine-tuning of each hormone level is required for AM development.

  18. Two-dimensional ultrasound receive array using an angle-tuned Fabry-Perot polymer film sensor for transducer field characterization and transmission ultrasound imaging.

    PubMed

    Beard, Paul Christopher

    2005-06-01

    A 2-D optical ultrasound receive array has been investigated. The transduction mechanism is based upon the detection of acoustically induced changes in the optical thickness of a thin polymer film acting as a Fabry-Perot sensing interferometer (FPI). By illuminating the sensor with a large-area laser beam and mechanically scanning a photodiode across the reflected output beam, while using a novel angle-tuned phase bias control system to optimally set the FPI working point, a notional 2-D ultrasound array was synthesized. To demonstrate the concept, 1-D and 2-D ultrasound field distributions produced by planar 3.5-MHz and focused 5-MHz PZT ultrasound transducers were mapped. The system was also evaluated by performing transmission ultrasound imaging of a spatially calibrated target. The "array" aperture, defined by the dimensions of the incident optical field, was elliptical, of dimensions 16 x 12 mm and spatially sampled in steps of 0.1 mm or 0.2 mm. Element sizes, defined by the photodiode aperture, of 0.8, 0.4, and 0.2 mm were variously used for these experiments. Two types of sensor were evaluated. One was a discrete 75-microm-thick polyethylene terephthalate FPI bonded to a polymer backing stub which had a wideband peak noise-equivalent pressure of 6.5 kPa and an acoustic bandwidth 12 MHz. The other was a 40-microm Parylene film FPI which was directly vacuum-deposited onto a glass backing stub and had an NEP of 8 kPa and an acoustic bandwidth of 17.5 MHz. It is considered that this approach offers an alternative to piezoelectric ultrasound arrays for transducer field characterization, transmission medical and industrial ultrasound imaging, biomedical photoacoustic imaging, and ultrasonic nondestructive testing.

  19. The role of Rabi splitting tuning in the dynamics of strongly coupled J-aggregates and surface plasmon polaritons in nanohole arrays

    NASA Astrophysics Data System (ADS)

    Wang, Hai; Toma, Andrea; Wang, Hai-Yu; Bozzola, Angelo; Miele, Ermanno; Haddadpour, Ali; Veronis, Georgios; de Angelis, Francesco; Wang, Lei; Chen, Qi-Dai; Xu, Huai-Liang; Sun, Hong-Bo; Zaccaria, Remo Proietti

    2016-07-01

    We have investigated the influence of Rabi splitting tuning on the dynamics of strongly coupled J-aggregate/surface plasmon polariton systems. In particular, the Rabi splitting was tuned by modifying the J-aggregate molecule concentration while a polaritonic system was provided by a nanostructure formed by holes array in a golden layer. From the periodic and concentration changes we have identified, through numerical and experimental steady-state analyses, the best geometrical configuration for maximizing Rabi splitting, which was then used for transient absorption measurements. It was found that in transient absorption spectra, under upper band excitation, two bleaching peaks appear when a nanostructured polaritonic pattern is used. Importantly, their reciprocal distance increases upon increase of J-aggregate concentration, a result confirmed by steady-state analysis. In a similar manner it was also found that the lifetime of the upper band is intimately related to the coupling strength. In particular, we argue that with strong coupling strength, i.e. high J-aggregate concentration, a short lifetime of the upper band has to be expected due to the suppression of the bottleneck effect. This result supports the idea that the dynamics of hybrid systems is profoundly dependent on Rabi splitting.

  20. Fine-tuning of age integrating magnetostratigraphy, radiocarbon dating, and carbonate cyclicity: Example of lacustrine sediments from Heqing basin (Yunnan, China) covering the past 1 Myr

    NASA Astrophysics Data System (ADS)

    Hu, Shouyun; Goddu, Srinivasa Rao; Appel, Erwin; Verosub, Ken

    2007-05-01

    convincing Milankovitch spectrum of whole-core carbonate data. The Fourier spectra of whole-core carbonate and susceptibility time series calibrated by the optimum age model show clear Milankovitch cyclicities (95, 41, 23, and 19 kyr) indicating that a global palaeoclimatic signal is recorded. According to this result the Heqing core spans almost the complete past 1 Myr (5-1001 ka). Detailed depth-to-age conversion is listed. The optimum age model can be used as a fine-tuned time basis for interpreting the existing data set of palaeoclimatic proxies which have been already measured for this sequence.

  1. Magnetic Field-Tuned Superconductor-Insulator Transition in One-Dimensional Arrays of Small Josephson Junctions

    NASA Astrophysics Data System (ADS)

    Kuo, Watson; Chen, C. D.

    2003-03-01

    We have studied experimentally the magnetic field induced superconductor-insulator quantum phase transition in one-dimensional arrays of small Josephson junctions. It is found that the critical magnetic field that separates the two phases corresponds to the onset of Coulomb blockade of Cooper pairs tunneling in the current-voltage characteristics. The resistance data are analyzed in the context of the superfluid-insulator transition in one dimension. Combining results from Haviland et. al.,2 we construct an experimental phase diagram using Josepshon coupling-to-charging energy ratio(EJ/ECP) and dissipation strength.

  2. Acoustic Beam Forming Array Using Feedback-Controlled Microphones for Tuning and Self-Matching of Frequency Response

    NASA Technical Reports Server (NTRS)

    Radcliffe, Eliott (Inventor); Naguib, Ahmed (Inventor); Humphreys, Jr., William M. (Inventor)

    2014-01-01

    A feedback-controlled microphone includes a microphone body and a membrane operatively connected to the body. The membrane is configured to be initially deflected by acoustic pressure such that the initial deflection is characterized by a frequency response. The microphone also includes a sensor configured to detect the frequency response of the initial deflection and generate an output voltage indicative thereof. The microphone additionally includes a compensator in electric communication with the sensor and configured to establish a regulated voltage in response to the output voltage. Furthermore, the microphone includes an actuator in electric communication with the compensator, wherein the actuator is configured to secondarily deflect the membrane in opposition to the initial deflection such that the frequency response is adjusted. An acoustic beam forming microphone array including a plurality of the above feedback-controlled microphones is also disclosed.

  3. Size tuning of Ag-decorated TiO₂ nanotube arrays for improved bactericidal capacity of orthopedic implants.

    PubMed

    Esfandiari, N; Simchi, A; Bagheri, R

    2014-08-01

    Surface modification of orthopedic implants using titanium dioxide nanotubes and silver nanoparticles (SNs) is a promising approach to prevent bacteria adhesion, biofilm formation, and implant infection. Herein, we utilized a straightforward and all-solution process to prepare silver-decorated TiO2 nanotube arrays with surface density of 10(3) to 10(4) per µm(2). With controlling the synthesis conditions, hexagonal closed-packed nanotubes with opening diameter of 30-100 nm that are decorated with SNs with varying sizes (12-40 nm) were prepared. Various analytical techniques were utilized to characterize the size, morphology, distribution, valance state, surface roughness, and composition of the prepared antibacterial films. The bactericidal capacity of the films were studied on Escherichia coli (E. coli) by drop-test method and correlated with the size and percentage of Ag as well as the surface density of TiO2 nanotube arrays. Synergetic effect of TiO2 nanotubes and SNs on the antibacterial activity of the composite films is shown. The bactericidal capacity is found to depend on the size characteristics of the Ag-TiO2 coating. The highest antibacterial activity is obtained for TiO2 nanotubes with opening diameter of about 100 nm and SNs with an average size of 20 nm. MTT assay using osteoblast MG63 cells was performed to examine the cell viability. We suggest that release rate of the silver ions is an important factor controlling the antibacterial activity. Additionally, the size dependency of the bactericidal capacity implies that electrical coupling between silver and TiO2 nanotubes and improved hydrophobicity of the coating might influence the bacterial behavior of the hybrid nanostructures.

  4. Extended x-ray absorption fine structure studies of a retrovirus: equine infectious anemia virus cysteine arrays are coordinated to zinc.

    PubMed

    Chance, M R; Sagi, I; Wirt, M D; Frisbie, S M; Scheuring, E; Chen, E; Bess, J W; Henderson, L E; Arthur, L O; South, T L

    1992-11-01

    Zinc finger arrays have been established as a critical structural feature of proteins involved in DNA recognition. Retroviral nucleocapsid proteins, which are involved in the binding of viral RNA, contain conserved cysteine-rich arrays that have been suggested to coordinate zinc. We provide metalloprotein structural data from an intact virus preparation that validate this hypothesis. Extended x-ray absorption fine structure (EXAFS) spectroscopy of well-characterized and active preparations of equine infectious anemia virus, compared with a peptide with known coordination and in combination with available biochemical and genetic data, defines a Cys3His1 coordination environment for zinc. The average of the Zn-S distances is 2.30(1) A and that of the Zn-N distance (to histidine) is 2.01(3) A.

  5. Importance of Hydrogen Bonding in Fine Tuning the [2Fe-2S] Cluster Redox Potential of HydC from Thermotoga maritima.

    PubMed

    Birrell, James A; Laurich, Christoph; Reijerse, Edward J; Ogata, Hideaki; Lubitz, Wolfgang

    2016-08-09

    Iron-sulfur clusters form one of the largest and most diverse classes of enzyme cofactors in nature. They may serve as structural factors, form electron transfer chains between active sites and external redox partners, or form components of enzyme active sites. Their specific role is a consequence of the cluster type and the surrounding protein environment. The relative effects of these factors are not completely understood, and it is not yet possible to predict the properties of iron-sulfur clusters based on amino acid sequences or rationally tune their properties to generate proteins with new desirable functions. Here, we generate mutations in a [2Fe-2S] cluster protein, the TmHydC subunit of the trimeric [FeFe]-hydrogenase from Thermotoga maritima, to study the factors that affect its redox potential. Saturation mutagenesis of Val131 was used to tune the redox potential over a 135 mV range and revealed that cluster redox potential and electronic properties correlate with amino acid hydrophobicity and the ability to form hydrogen bonds to the cluster. Proline scanning mutagenesis between pairs of ligating cysteines was used to remove backbone amide hydrogen bonds to the cluster and decrease the redox potential by up to 132 mV, without large structural changes in most cases. However, substitution of Gly83 with proline caused a change of HydC to a [4Fe-4S] cluster protein with a redox potential of -526 mV. Together, these results confirm the importance of hydrogen bonding in tuning cluster redox potentials and demonstrate the versatility of iron-sulfur cluster protein folds at binding different types of clusters.

  6. NHC-Ag/Pd-Catalyzed Reductive Carboxylation of Terminal Alkynes with CO2 and H2 : A Combined Experimental and Computational Study for Fine-Tuned Selectivity.

    PubMed

    Yu, Dingyi; Zhou, Feng; Lim, Diane S W; Su, Haibin; Zhang, Yugen

    2017-03-09

    Reductive carboxylation of terminal alkynes utilizing CO2 and H2 as reactants is an interesting and challenging transformation. Theoretical calculations indicated it would be kinetically possible to obtain cinnamic acid, the reductive carboxylation product, from phenylacetylene in a CO2 /H2 system with an N-heterocyclic carbene (NHC)-supported Ag/Pd bimetallic catalysts through competitive carboxylation/hydrogenation cascade reactions in one step. These calculations were verified experimentally with a poly-NHC-supported Ag/Pd catalyst. By tuning the catalyst composition and reaction temperature, phenylacetylene was selectively converted to cinnamic acid, hydrocinnamic acid, or phenylpropiolic acid in excellent yields.

  7. Characterization of nonlinear dielectric films for the tuning of microwave cavities for axion searches

    NASA Astrophysics Data System (ADS)

    Salemi, Chiara; Bowring, Daniel; Sonnenschein, Andrew

    2016-09-01

    The axion is a hypothetical particle that can solve the strong CP problem and that may be the primary component of dark matter in the universe. Experiments such as the Axion Dark Matter eXperiment (ADMX) hope to find the axion through its coupling to photons in the presence of a strong magnetic field. This coupling can be detected using a microwave cavity whose fundamental resonance frequency is matched to that of the photons. By tuning the cavity resonance frequency, the corresponding axion mass range can be scanned. For axion searches above 1GHz, future generations of ADMX may use an array of small cavities locked to the same frequency. These cavities will be coarsely tuned using a tuning rod as is done in the current generation of ADMX, but fine tuning of individual resonators will be necessary for multi-cavity arrays. A candidate fine tuning method uses nonlinear dielectric films inside the cavities. DC-biasing the films changes their dielectric constant, affecting the frequencies of the cavity modes. This method makes frequency-matched resonator arrays more practical by saving space and minimizing heat load inside the cryostat. This poster presents RF design and simulation and preliminary measurements on the coplanar waveguide resonators used to test the films.

  8. Thermoelectric properties of fine-grained FeVSb half-Heusler alloys tuned to p-type by substituting vanadium with titanium

    SciTech Connect

    Zou, Minmin; Li, Jing-Feng; Kita, Takuji

    2013-02-15

    Fine-grained Ti-doped FeVSb half-Heusler alloys were synthesized by combining mechanical alloying and spark plasma sintering and their thermoelectric properties were investigated with an emphasis on the influences of Ti doping and phase purity. It was found that substituting V with Ti can change the electrical transport behavior from n-type to p-type due to one less valence electron of Ti than V, and the sample with nominal composition FeV{sub 0.8}Ti{sub 0.4}Sb exhibits the largest Seebeck coefficient and the maximum power factor. By optimizing the sintering temperature and applying annealing treatment, the power factor is significantly improved and the thermal conductivity is reduced simultaneously, resulting in a ZT value of 0.43 at 500 Degree-Sign C, which is relatively high as for p-type half-Heusler alloys containing earth-abundant elements. - Graphical abstract: Fine-grained Ti-doped FeVSb alloys were prepared by the MA-SPS method. The maximum ZT value reaches 0.43 at 500 Degree-Sign C, which is relatively high for p-type half-Heusler alloys. Highlights: Black-Right-Pointing-Pointer Ti-doped FeVSb half-Heusler alloys were synthesized by combining MA and SPS. Black-Right-Pointing-Pointer Substituting V with Ti changes the electrical behavior from n-type to p-type. Black-Right-Pointing-Pointer Thermoelectric properties are improved by optimizing sintering temperature. Black-Right-Pointing-Pointer Thermoelectric properties are further improved by applying annealing treatment. Black-Right-Pointing-Pointer A high ZT value of 0.43 is obtained at 500 Degree-Sign C for p-type Ti-doped FeVSb alloys.

  9. Fine tuning of magnetite nanoparticle size distribution using dissymmetric potential pulses in the presence of biocompatible surfactants and the electrochemical characterization of the nanoparticles.

    PubMed

    Rodríguez-López, A; Cruz-Rivera, J J; Elías-Alfaro, C G; Betancourt, I; Ruiz-Silva, H; Antaño-López, R

    2015-01-01

    The effects of varying the surfactant concentration and the anodic pulse potential on the properties and electrochemical behaviors of magnetite nanoparticles were investigated. The nanoparticles were synthesized with an electrochemical method based on applying dissymmetric potential pulses, which offers the advantage that can be used to tune the particle size distribution very precisely in the range of 10 to 50 nm. Under the conditions studied, the surfactant concentration directly affects the size distribution, with higher concentrations producing narrower distributions. Linear voltammetry was used to characterize the electrochemical behavior of the synthesized nanoparticles in both the anodic and cathodic regions, which are attributed to the oxidation of Fe(2+) and the reduction of Fe(3+); these species are part of the spinel structure of magnetite. Electrochemical impedance spectroscopy data indicated that the reduction and oxidation reactions of the nanoparticles are not controlled by the mass transport step, but by the charge transfer step. The sample with the highest saturation magnetization was that synthesized in the presence of polyethylene glycol.

  10. Codon populations in single-stranded whole human genome DNA Are fractal and fine-tuned by the Golden Ratio 1.618.

    PubMed

    Perez, Jean-Claude

    2010-09-01

    This new bioinformatics research bridges Genomics and Mathematics. We propose a universal "Fractal Genome Code Law": The frequency of each of the 64 codons across the entire human genome is controlled by the codon's position in the Universal Genetic Code table. We analyze the frequency of distribution of the 64 codons (codon usage) within single-stranded DNA sequences. Concatenating 24 Human chromosomes, we show that the entire human genome employs the well known universal genetic code table as a macro structural model. The position of each codon within this table precisely dictates its population. So the Universal Genetic Code Table not only maps codons to amino acids, but serves as a global checksum matrix. Frequencies of the 64 codons in the whole human genome scale are a self-similar fractal expansion of the universal genetic code. The original genetic code kernel governs not only the micro scale but the macro scale as well. Particularly, the 6 folding steps of codon populations modeled by the binary divisions of the "Dragon fractal paper folding curve" show evidence of 2 attractors. The numerical relationship between the attractors is derived from the Golden Ratio. We demonstrate that: (i) The whole Human Genome Structure uses the Universal Genetic Code Table as a tuning model. It predetermines global codons proportions and populations. The Universal Genetic Code Table governs both micro and macro behavior of the genome. (ii) We extend the Chargaff's second rule from the domain of single TCAG nucleotides to the larger domain of codon triplets. (iii) Codon frequencies in the human genome are clustered around 2 fractal-like attractors, strongly linked to the golden ratio 1.618.

  11. The diatom Phaeodactylum tricornutum adjusts nonphotochemical fluorescence quenching capacity in response to dynamic light via fine-tuned Lhcx and xanthophyll cycle pigment synthesis.

    PubMed

    Lepetit, Bernard; Gélin, Gautier; Lepetit, Mariana; Sturm, Sabine; Vugrinec, Sascha; Rogato, Alessandra; Kroth, Peter G; Falciatore, Angela; Lavaud, Johann

    2017-04-01

    Diatoms contain a highly flexible capacity to dissipate excessively absorbed light by nonphotochemical fluorescence quenching (NPQ) based on the light-induced conversion of diadinoxanthin (Dd) into diatoxanthin (Dt) and the presence of Lhcx proteins. Their NPQ fine regulation on the molecular level upon a shift to dynamic light conditions is unknown. We investigated the regulation of Dd + Dt amount, Lhcx gene and protein synthesis and NPQ capacity in the diatom Phaeodactylum tricornutum after a change from continuous low light to 3 d of sine (SL) or fluctuating (FL) light conditions. Four P. tricornutum strains with different NPQ capacities due to different expression of Lhcx1 were included. All strains responded to dynamic light comparably, independently of initial NPQ capacity. During SL, NPQ capacity was strongly enhanced due to a gradual increase of Lhcx2 and Dd + Dt amount. During FL, cells enhanced their NPQ capacity on the first day due to increased Dd + Dt, Lhcx2 and Lhcx3; already by the second day light acclimation was accomplished. While quenching efficiency of Dt was strongly lowered during SL conditions, it remained high throughout the whole FL exposure. Our results highlight a more balanced and cost-effective photoacclimation strategy of P. tricornutum under FL than under SL conditions.

  12. Linking landscape characteristics to mineral site use by band-tailed pigeons in Western Oregon: Coarse-filter conservation with fine-filter tuning

    USGS Publications Warehouse

    Overton, C.T.; Schmitz, R.A.; Casazza, M.L.

    2006-01-01

    Mineral sites are scarce resources of high ion concentration used heavily by the Pacific Coast subpopulation of band-tailed pigeons. Over 20% of all known mineral sites used by band-tailed pigeons in western Oregon, including all hot springs, have been abandoned. Prior investigations have not analyzed stand or landscape level habitat composition in relation to band-tailed pigeon use of mineral sites. We used logistic regression models to evaluate the influence of habitat types, identified from Gap Analysis Program (GAP) products at two spatial scales, on the odds of mineral site use in Oregon (n = 69 currently used and 20 historically used). Our results indicated that the odds of current use were negatively associated with non-forested terrestrial and private land area around mineral sites. Similarly, the odds of current mineral site use were positively associated with forested and special status (GAP stewardship codes 1 and 2) land area. The most important variable associated with the odds of mineral site use was the amount of non-forested land cover at either spatial scale. Our results demonstrate the utility of meso-scale geographic information designed for regional, coarse-filter approaches to conservation in fine-filter investigation of wildlife-habitat relationships. Adjacent landcover and ownership status explain the pattern of use for known mineral sites in western Oregon. In order for conservation and management activities for band-tailed pigeons to be successful, mineral sites need to be addressed as important and vulnerable resources. Management of band-tailed pigeons should incorporate the potential for forest management activities and land ownership patterns to influence the risk of mineral site abandonment.

  13. Effects of fine metal oxide particle dopant on the acoustic properties of silicone rubber lens for medical array probe.

    PubMed

    Hosono, Yasuharu; Yamashita, Yohachi; Itsumi, Kazuhiro

    2007-08-01

    The effects of fine metal oxide particles, particularly those of high-density elements (7.7 to 9.7 x 10(3) kg/m3), on the acoustic properties of silicone rubber have been investigated in order to develop an acoustic lens with a low acoustic attenuation. Silicone rubber doped with Yb2O3 powder having nanoparticle size of 16 nm showed a lower acoustic attenuation than silicone rubber doped with powders of CeO2, Bi2O3, Lu2O3 and HfO2. The silicone rubber doped with Yb2O3 powder showed a sound speed of 0.88 km/s, an acoustic impedance of 1.35 x 10(6) kg/m2s, an acoustic attenuation of 0.93 dB/mmMHz, and a Shore A hardness of 55 at 37 degrees C. Although typical silicone rubber doped with SiO2 (2.6 x 10(3) kg/m3) shows a sound speed of about 1.00 km/s, heavy metal oxide particles decreased the sound velocities to lower than 0.93 km/s. Therefore, an acoustic lens of silicone rubber doped with Yb2O3 powder provides increased sensitivity because it realizes a thinner acoustic lens than is conventionally used due to its low sound speed. Moreover, it has an advantage in that a focus point is not changed when the acoustic lens is pressed to a human body due to its reasonable hardness.

  14. Pressure-driven assembly of spherical nanoparticles and formation of 1D nanostructure arrays.

    SciTech Connect

    Wu, Huimeng

    2010-08-01

    External pressure was used to engineer nanoparticle assembly. Reversible manipulation of the unit-cell dimensions of a 3D ordered nanoparticle array under a hydrostatic pressure field enabled the fine-tuning of the interparticle distance. Under a uniaxial pressure field, nanoparticles were forced to contact and coalesce into nanorods or nanowires and ordered ultrahigh-density arrays (see picture; small arrows denote pressure).

  15. Tuning Parameters in Heuristics by Using Design of Experiments Methods

    NASA Technical Reports Server (NTRS)

    Arin, Arif; Rabadi, Ghaith; Unal, Resit

    2010-01-01

    With the growing complexity of today's large scale problems, it has become more difficult to find optimal solutions by using exact mathematical methods. The need to find near-optimal solutions in an acceptable time frame requires heuristic approaches. In many cases, however, most heuristics have several parameters that need to be "tuned" before they can reach good results. The problem then turns into "finding best parameter setting" for the heuristics to solve the problems efficiently and timely. One-Factor-At-a-Time (OFAT) approach for parameter tuning neglects the interactions between parameters. Design of Experiments (DOE) tools can be instead employed to tune the parameters more effectively. In this paper, we seek the best parameter setting for a Genetic Algorithm (GA) to solve the single machine total weighted tardiness problem in which n jobs must be scheduled on a single machine without preemption, and the objective is to minimize the total weighted tardiness. Benchmark instances for the problem are available in the literature. To fine tune the GA parameters in the most efficient way, we compare multiple DOE models including 2-level (2k ) full factorial design, orthogonal array design, central composite design, D-optimal design and signal-to-noise (SIN) ratios. In each DOE method, a mathematical model is created using regression analysis, and solved to obtain the best parameter setting. After verification runs using the tuned parameter setting, the preliminary results for optimal solutions of multiple instances were found efficiently.

  16. Dark interactions and cosmological fine-tuning

    SciTech Connect

    Quartin, Miguel; Calvao, Mauricio O; Joras, Sergio E; Reis, Ribamar R R; Waga, Ioav E-mail: orca@if.ufrj.br E-mail: ribamar@if.ufrj.br

    2008-05-15

    Cosmological models involving an interaction between dark matter and dark energy have been proposed in order to solve the so-called coincidence problem. Different forms of coupling have been studied, but there have been claims that observational data seem to narrow (some of) them down to something annoyingly close to the {Lambda}CDM (CDM: cold dark matter) model, thus greatly reducing their ability to deal with the problem in the first place. The smallness problem of the initial energy density of dark energy has also been a target of cosmological models in recent years. Making use of a moderately general coupling scheme, this paper aims to unite these different approaches and shed some light on whether this class of models has any true perspective in suppressing the aforementioned issues that plague our current understanding of the universe, in a quantitative and unambiguous way.

  17. Strigolactones fine-tune the root system.

    PubMed

    Rasmussen, Amanda; Depuydt, Stephen; Goormachtig, Sofie; Geelen, Danny

    2013-10-01

    Strigolactones were originally discovered to be involved in parasitic weed germination, in mycorrhizal association and in the control of shoot architecture. Despite their clear role in rhizosphere signaling, comparatively less attention has been given to the belowground function of strigolactones on plant development. However, research has revealed that strigolactones play a key role in the regulation of the root system including adventitious roots, primary root length, lateral roots, root hairs and nodulation. Here, we review the recent progress regarding strigolactone regulation of the root system and the antagonism and interplay with other hormones.

  18. Fine Tuning Gene Expression: The Epigenome

    PubMed Central

    Mohtat, Davoud; Susztak, Katalin

    2011-01-01

    An epigenetic trait is a stably inherited phenotype resulting from changes in a chromosome without alterations in the DNA sequence. Epigenetic modifications, such as; DNA methylation, together with covalent modification of histones, are thought to alter chromatin density and accessibility of the DNA to cellular machinery, thereby modulating the transcriptional potential of the underlying DNA sequence. As epigenetic marks under environmental influence, epigenetics provides an added layer of variation that might mediate the relationship between genotype and internal and external environmental factors. Integration of our knowledge in genetics, epigenomics and genomics with the use of systems biology tools may present investigators with new powerful tools to study many complex human diseases such as kidney disease. PMID:21044758

  19. Riboregulators: Fine-Tuning Virulence in Shigella.

    PubMed

    Fris, Megan E; Murphy, Erin R

    2016-01-01

    Within the past several years, RNA-mediated regulation (ribo-regulation) has become increasingly recognized for its importance in controlling critical bacterial processes. Regulatory RNA molecules, or riboregulators, are perpetually responsive to changes within the micro-environment of a bacterium. Notably, several characterized riboregulators control virulence in pathogenic bacteria, as is the case for each riboregulator characterized to date in Shigella. The timing of virulence gene expression and the ability of the pathogen to adapt to rapidly changing environmental conditions is critical to the establishment and progression of infection by Shigella species; ribo-regulators mediate each of these important processes. This mini review will present the current state of knowledge regarding RNA-mediated regulation in Shigella by detailing the characterization and function of each identified riboregulator in these pathogens.

  20. Riboregulators: Fine-Tuning Virulence in Shigella

    PubMed Central

    Fris, Megan E.; Murphy, Erin R.

    2016-01-01

    Within the past several years, RNA-mediated regulation (ribo-regulation) has become increasingly recognized for its importance in controlling critical bacterial processes. Regulatory RNA molecules, or riboregulators, are perpetually responsive to changes within the micro-environment of a bacterium. Notably, several characterized riboregulators control virulence in pathogenic bacteria, as is the case for each riboregulator characterized to date in Shigella. The timing of virulence gene expression and the ability of the pathogen to adapt to rapidly changing environmental conditions is critical to the establishment and progression of infection by Shigella species; ribo-regulators mediate each of these important processes. This mini review will present the current state of knowledge regarding RNA-mediated regulation in Shigella by detailing the characterization and function of each identified riboregulator in these pathogens. PMID:26858941

  1. Mechanism of Fine-tuning pH Sensors in Proprotein Convertases: IDENTIFICATION OF A pH-SENSING HISTIDINE PAIR IN THE PROPEPTIDE OF PROPROTEIN CONVERTASE 1/3.

    PubMed

    Williamson, Danielle M; Elferich, Johannes; Shinde, Ujwal

    2015-09-18

    The propeptides of proprotein convertases (PCs) regulate activation of cognate protease domains by sensing pH of their organellar compartments as they transit the secretory pathway. Earlier experimental work identified a conserved histidine-encoded pH sensor within the propeptide of the canonical PC, furin. To date, whether protonation of this conserved histidine is solely responsible for PC activation has remained unclear because of the observation that various PC paralogues are activated at different organellar pH values. To ascertain additional determinants of PC activation, we analyzed PC1/3, a paralogue of furin that is activated at a pH of ∼5.4. Using biophysical, biochemical, and cell-based methods, we mimicked the protonation status of various histidines within the propeptide of PC1/3 and examined how such alterations can modulate pH-dependent protease activation. Our results indicate that whereas the conserved histidine plays a crucial role in pH sensing and activation of this protease an additional histidine acts as a "gatekeeper" that fine-tunes the sensitivity of the PC1/3 propeptide to facilitate the release inhibition at higher proton concentrations when compared with furin. Coupled with earlier analyses that highlighted the enrichment of the amino acid histidine within propeptides of secreted eukaryotic proteases, our work elucidates how secreted proteases have evolved to exploit the pH of the secretory pathway by altering the spatial juxtaposition of titratable groups to regulate their activity in a spatiotemporal fashion.

  2. Transcriptomics of the interaction between the monopartite phloem-limited geminivirus tomato yellow leaf curl Sardinia virus and Solanum lycopersicum highlights a role for plant hormones, autophagy and plant immune system fine tuning during infection.

    PubMed

    Miozzi, Laura; Napoli, Chiara; Sardo, Luca; Accotto, Gian Paolo

    2014-01-01

    Tomato yellow leaf curl Sardinia virus (TYLCSV), a DNA virus belonging to the genus Begomovirus, causes severe losses in tomato crops. It infects only a limited number of cells in the vascular tissues, making difficult to detect changes in host gene expression linked to its presence. Here we present the first microarray study of transcriptional changes induced by the phloem-limited geminivirus TYLCSV infecting tomato, its natural host. The analysis was performed on the midrib of mature leaves, a material naturally enriched in vascular tissues. A total of 2206 genes were up-regulated and 1398 were down-regulated in infected plants, with an overrepresentation of genes involved in hormone metabolism and responses, nucleic acid metabolism, regulation of transcription, ubiquitin-proteasome pathway and autophagy among those up-regulated, and in primary and secondary metabolism, phosphorylation, transcription and methylation-dependent chromatin silencing among those down-regulated. Our analysis showed a series of responses, such as the induction of GA- and ABA-responsive genes, the activation of the autophagic process and the fine tuning of the plant immune system, observed only in TYLCSV-tomato compatible interaction so far. On the other hand, comparisons with transcriptional changes observed in other geminivirus-plant interactions highlighted common host responses consisting in the deregulation of biotic stress responsive genes, key enzymes in the ethylene biosynthesis and methylation cycle, components of the ubiquitin proteasome system and DNA polymerases II. The involvement of conserved miRNAs and of solanaceous- and tomato-specific miRNAs in geminivirus infection, investigated by integrating differential gene expression data with miRNA targeting data, is discussed.

  3. Improving Electrocatalysts for O2 Reduction by Fine-Tuning the Pt-Support Interaction: Pt Monolayer on the Surfaces of a Pd3Fe(111) Single-Crystal Alloy

    SciTech Connect

    Zhou, W.P.; Yang, X.; Vukmirovic, M.B.; Koel, B.E.; Jiao, J.; Peng, G.; Mavrikakis, M.; Adzic, R.R.

    2009-09-09

    We improved the effectiveness of Pt monolayer electrocatalysts for the oxygen-reduction reaction (ORR) using a novel approach to fine-tuning the Pt monolayer interaction with its support, exemplified by an annealed Pd{sub 3}Fe(111) single-crystal alloy support having a segregated Pd layer. Low-energy ion scattering and low-energy electron diffraction studies revealed that a segregated Pd layer, with the same structure as Pd (111), is formed on the surface of high-temperature-annealed Pd{sub 3}Fe(111). This Pd layer is considerably more active than Pd(111); its ORR kinetics is comparable to that of a Pt(111) surface. The enhanced catalytic activity of the segregated Pd layer compared to that of bulk Pd apparently reflects the modification of Pd surface's electronic properties by underlying Fe. The Pd{sub 3}Fe(111) suffers a large loss in ORR activity when the subsurface Fe is depleted by potential cycling (i.e., repeated excursions to high potentials in acid solutions). The Pd{sub 3}Fe(111) surface is an excellent substrate for a Pt monolayer ORR catalyst, as verified by its enhanced ORR kinetics on PT{sub ML}/Pd/Pd{sub 3}Fe(111). Our density functional theory studies suggest that the observed enhancement of ORR activity originates mainly from the destabilization of OH binding and the decreased Pt-OH coverage on the Pt/Pd/Pd{sub 3}Fe(111) surface. The activity of Pt{sub ML}/Pd(111) and Pt(111) is limited by OH removal, whereas the activity of Pt{sub ML}/Pd/Pd{sub 3}Fe(111) is limited by the O-O bond scission, which places these two surfaces on the two sides of the volcano plot.

  4. Improving Electrocatalysts for O2 Reduction by Fine-Tuning the Pt-Support Interaction: Pt Monolayer on the Surfaces of a Pd3Fe(111) Single-Crystal Alloy

    SciTech Connect

    Zhou, Wei-Ping; Yang, Xiaofang; Vukmirovic, Miomir B.; Koel, Bruce E.; Jiao, Jiao; Peng, Guowen; Mavrikakis, Manos; Adzic, Radoslav R.

    2009-09-09

    We improved the effectiveness of Pt monolayer electrocatalysts for the oxygen-reduction reaction (ORR) using a novel approach to fine-tuning the Pt monolayer interaction with its support, exemplified by an annealed Pd3Fe(111) single-crystal alloy support having a segregated Pd layer. Low-energy ion scattering and low-energy electron diffraction studies revealed that a segregated Pd layer, with the same structure as Pd (111), is formed on the surface of high-temperature-annealed Pd3Fe(111). This Pd layer is considerably more active than Pd(111); its ORR kinetics is comparable to that of a Pt(111) surface. The enhanced catalytic activity of the segregated Pd layer compared to that of bulk Pd apparently reflects the modification of Pd surface’s electronic properties by underlying Fe. The Pd3Fe(111) suffers a large loss in ORR activity when the subsurface Fe is depleted by potential cycling (i.e., repeated excursions to high potentials in acid solutions). The Pd3Fe(111) surface is an excellent substrate for a Pt monolayer ORR catalyst, as verified by its enhanced ORR kinetics on PTML/Pd/Pd3Fe(111). Our density functional theory studies suggest that the observed enhancement of ORR activity originates mainly from the destabilization of OH binding and the decreased Pt-OH coverage on the Pt/Pd/Pd3Fe(111) surface. The activity of PtML/Pd(111) and Pt(111) is limited by OH removal, whereas the activity of PtML/Pd/Pd3Fe(111) is limited by the O-O bond scission, which places these two surfaces on the two sides of the volcano plot.

  5. A new direction in dye-sensitized solar cells redox mediator development: in situ fine-tuning of the cobalt(II)/(III) redox potential through Lewis base interactions.

    PubMed

    Kashif, Muhammad K; Axelson, Jordan C; Duffy, Noel W; Forsyth, Craig M; Chang, Christopher J; Long, Jeffrey R; Spiccia, Leone; Bach, Udo

    2012-10-10

    Dye-sensitized solar cells (DSCs) are an attractive renewable energy technology currently under intense investigation. In recent years, one area of major interest has been the exploration of alternatives to the classical iodide/triiodide redox shuttle, with particular attention focused on cobalt complexes with the general formula [Co(L)(n)](2+/3+). We introduce a new approach to designing redox mediators that involves the application of [Co(PY5Me(2))(MeCN)](2+/3+) complexes, where PY5Me(2) is the pentadentate ligand, 2,6-bis(1,1-bis(2-pyridyl)ethyl)pyridine. It is shown, by X-ray crystallography, that the axial acetonitrile (MeCN) ligand can be replaced by more strongly coordinating Lewis bases (B) to give complexes with the general formula [Co(PY5Me(2))(B)](2+/3+), where B = 4-tert-butylpyridine (tBP) or N-methylbenzimidazole (NMBI). These commonly applied DSC electrolyte components are used for the first time to fine-tune the potential of the redox couple to the requirements of the dye through coordinative interactions with the Co(II/III) centers. Application of electrolytes based on the [Co(PY5Me(2))(NMBI)](2+/3+) complex in combination with a commercially available organic sensitizer has enabled us to attain DSC efficiencies of 8.4% and 9.2% at a simulated light intensity of 100% sun (1000 W m(-2) AM1.5 G) and at 10% sun, respectively, higher than analogous devices applying the [Co(bpy)(3)](2+/3+) redox couple, and an open circuit voltage (V(oc)) of almost 1.0 V at 100% sun for devices constructed with the tBP complex.

  6. TUNE: Compiler-Directed Automatic Performance Tuning

    SciTech Connect

    Hall, Mary

    2014-09-18

    This project has developed compiler-directed performance tuning technology targeting the Cray XT4 Jaguar system at Oak Ridge, which has multi-core Opteron nodes with SSE-3 SIMD extensions, and the Cray XE6 Hopper system at NERSC. To achieve this goal, we combined compiler technology for model-guided empirical optimization for memory hierarchies with SIMD code generation, which have been developed by the PIs over the past several years. We examined DOE Office of Science applications to identify performance bottlenecks and apply our system to computational kernels that operate on dense arrays. Our goal for this performance-tuning technology has been to yield hand-tuned levels of performance on DOE Office of Science computational kernels, while allowing application programmers to specify their computations at a high level without requiring manual optimization. Overall, we aim to make our technology for SIMD code generation and memory hierarchy optimization a crucial component of high-productivity Petaflops computing through a close collaboration with the scientists in national laboratories.

  7. Beam tuning

    SciTech Connect

    Pardo, R.C.; Zinkann, G.P.

    1995-08-01

    A program for configuring the linac, based on previously run configurations for any desired beam was used during the past year. This program uses only a small number of empirical tunes to scale resonator fields to properly accelerate a beam with a different charge-to-mass (q/A) ratio from the original tune configuration. The program worked very well for the PII linac section where we can easily match a new beam`s arrival phase and velocity to the tuned value. It was also fairly successful for the Booster and ATLAS sections of the linac, but not as successful as for the PII linac. Most of the problems are associated with setting the beam arrival time correctly for each major linac section. This problem is being addressed with the development of the capacitive pickup beam phase monitor discussed above. During the next year we expect to improve our ability to quickly configure the linac for new beams and reduce the time required for linac tuning. Already the time required for linac tuning as a percentage of research hours has decreased from 22% in FY 1993 to 15% in the first quarter of FY 1995.

  8. Shrunk to femtolitre: Tuning high-throughput monodisperse water-in-oil droplet arrays for ultra-small micro-reactors

    NASA Astrophysics Data System (ADS)

    Wu, Tianzhun; Hirata, Katsuki; Suzuki, Hiroaki; Xiang, Rong; Tang, Zikang; Yomo, Tetsuya

    2012-08-01

    We report a facile, low-cost, and high-yielding microfluidic technology for in situ generating and arraying water-in-oil droplets by shrinking them to the order of femtolitres (fLs) as scalable batch micro-reactors. Instead of generating ultra-small droplets by the direct atomization, which requires dedicate control and high energy input, we shrink droplets to stable smaller ones by utilizing the controlled water diffusion in oil. This "shrunk to fL" method is combined with a three-dimensional microwell design to create high-density addressable droplet arrays. As the result, scalable, high-throughput, and well-aligned W/O arrays with excellent long-term stability and predicable droplet sizes have been achieved.

  9. Collapse of the EPR fine structure of a one-dimensional array of weakly interacting binuclear units: A dimensional quantum phase transition

    NASA Astrophysics Data System (ADS)

    Calvo, Rafael; Abud, Julián E.; Sartoris, Rosana P.; Santana, Ricardo C.

    2011-09-01

    Binuclear (also called dimeric) compounds with pairs of antiferromagnetically coupled spins ½, S1 and S2 (Hex = -J0 S1.S2, with J0<0 for antiferromagnets), have been around for ˜60 years, providing roots to the field of molecular magnetism. In addition, as reported in recent years, weak interactions between binuclear units in a crystalline network give rise to interesting systems of interacting bosons having an energy gap, which are important in the study of quantum phenomena in many body systems coupled by stochastic distributions of interactions. Binuclear compounds have gained new relevance in the last decade with the observation of Bose-Einstein condensation. In this work, we use electron paramagnetic resonance (EPR) to study the role of weak inter-binuclear exchange couplings J’ (|J’| ≪|J0|) in the spectra, elementary excitations, and spin dynamics of a one-dimensional (1-D) array of antiferromagnetic (AFM) binuclear units in the hybrid (organic-inorganic) CuII compound [Cu(CH3COO)(phen)(H2O)]2·(NO3)2·4H2O. In this material, the acetate (CH3COO)- anion supports the intra-binuclear exchange coupling J0, and the stacking of the (phen) = 1,10-phenanthroline rings of neighbor units supports the inter-binuclear interactions J', giving rise to well-isolated chains. This has advantages over other binuclear compounds studied previously because magnetically equal units are arranged in a 1-D spatial arrangement along the direction of their symmetry axis, simplifying the analysis of the data and allowing a simpler treatment. In addition, single crystals of good quality allow detailed EPR experiments.EPR spectra were collected at ˜33.8 and ˜9.4-9.8 GHz in oriented single crystals at room temperature and in powder samples at temperatures (T) between 10 and 300 K. By varying the energy levels of the binuclear units with the magnetic field orientation, or changing the population of the excited triplet state with temperature and, consequently, the effective

  10. Tuning Optical Properties of Two-Dimensional Ordered Arrays of Silica/Gold and Silver Core/Shell Structured Nanoparticles in Near-Infrared Region

    NASA Astrophysics Data System (ADS)

    Sugawa, Kosuke; Sakai, Tatsuya; Tanaka, Daido; Akiyama, Tsuyoshi

    2012-04-01

    Core/shell type nanoparticles, in which the shell consists of a thin layer of metal and the core consists of monodispersed dielectric nanoparticles, are of great interest owing to their characteristic plasmonic properties. In this study, we have fabricated highly regular two-dimensional arrays of silica-core/gold (or silver)-shell nanoparticles protected with polyvinylpyrrolidone (PVP) by drop-casting their colloidal ethanol solutions onto tilted glass plates. The structure and plasmonic properties of the arrays were evaluated by visible/near-infrared transmission absorption spectroscopy and scanning electron microscopy (SEM). The characteristic broad plasmon band in the near-infrared wavelength region, derived from a hybridized mode of dipolar plasmon modes of the individual core/shell nanoparticle, appeared by changing the concentration of PVP added.

  11. 3D Ta/TaO x /TiO2/Ti synaptic array and linearity tuning of weight update for hardware neural network applications

    NASA Astrophysics Data System (ADS)

    Wang, I.-Ting; Chang, Chih-Cheng; Chiu, Li-Wen; Chou, Teyuh; Hou, Tuo-Hung

    2016-09-01

    The implementation of highly anticipated hardware neural networks (HNNs) hinges largely on the successful development of a low-power, high-density, and reliable analog electronic synaptic array. In this study, we demonstrate a two-layer Ta/TaO x /TiO2/Ti cross-point synaptic array that emulates the high-density three-dimensional network architecture of human brains. Excellent uniformity and reproducibility among intralayer and interlayer cells were realized. Moreover, at least 50 analog synaptic weight states could be precisely controlled with minimal drifting during a cycling endurance test of 5000 training pulses at an operating voltage of 3 V. We also propose a new state-independent bipolar-pulse-training scheme to improve the linearity of weight updates. The improved linearity considerably enhances the fault tolerance of HNNs, thus improving the training accuracy.

  12. Tunable elastomer-based virtually imaged phased array.

    PubMed

    Metz, Philipp; Block, Hendrik; Behnke, Christopher; Krantz, Matthias; Gerken, Martina; Adam, Jost

    2013-02-11

    Virtually imaged phased arrays (VIPAs) offer a high potential for wafer-level integration and superior optical properties compared to conventional gratings. We introduce an elastomer-based tunable VIPA enabling fine tuning of the dispersion characteristics. It consists of a poly-dimethylsiloxane (PDMS) layer sandwiched between silver bottom and top coatings, which form the VIPA's high reflective and semi-transparent mirror, respectively. The latter also acts as an electrode for Joule heating, such that the optical PDMS resonator cavity tuning is carried out via a combination of thermal expansion and the thermo-optic effect. Analogous to the free spectral range (FSR), based on a VIPA specific dispersion law, we introduce a new characteristic VIPA performance measure, namely the free angular range (FAR). We report a tuning span of one FAR achieved by a 7.2K temperature increase of a 170μm PDMS VIPA. Both resonance quality and tunability are analyzed in numerical simulations and experiments.

  13. Tuning the magnetic anisotropy of Co-Ni nanowires: comparison between single nanowires and nanowire arrays in hard-anodic aluminum oxide membranes.

    PubMed

    Vega, V; Böhnert, T; Martens, S; Waleczek, M; Montero-Moreno, J M; Görlitz, D; Prida, V M; Nielsch, K

    2012-11-23

    Co(x)Ni(1-x) alloy nanowires with varying Co content (0 ≤ x ≤ 0.95), having a diameter of 130 nm and length of around 20 μm, are synthesized by template-assisted electrodeposition into the nanopores of SiO(2) conformal coated hard-anodic aluminum oxide membranes. The magneto-structural properties of both single isolated nanowires and hexagonally ordered nanowire arrays of Co-Ni alloys are systematically studied by means of magneto-optical Kerr effect magnetometry and vibrating sample magnetometry, respectively, allowing us to compare different alloy compositions and to distinguish between the magnetostatic and magnetocrystalline contributions to the effective magnetic anisotropy for each system. The excellent tunable soft magnetic properties and magnetic bistability exhibited by low Co content Co-Ni nanowires indicate that they might become the material of choice for the development of nanostructured magnetic systems and devices as an alternative to Fe-Ni alloy based systems, being chemically more robust. Furthermore, Co contents higher than 51 at.% allow us to modify the magnetic behavior of Co-rich nanowires by developing well controlled magnetocrystalline anisotropy, which is desirable for data storage applications.

  14. Array-CGH fine mapping of minor and cryptic HR-CGH detected genomic imbalances in 80 out of 590 patients with abnormal development.

    PubMed

    Lybaek, Helle; Meza-Zepeda, Leonardo A; Kresse, Stine H; Høysaeter, Trude; Steen, Vidar M; Houge, Gunnar

    2008-11-01

    During a 6-year period, 590 patients suspected of having a minor or cryptic genomic imbalance as the cause of mental retardation with dysmorphic signs +/- malformations have been investigated with high-resolution comparative genomic hybridisation (HR-CGH) in our diagnostic laboratory. Thirty-six patients had a small chromosomal aberration detected by routine karyotyping, and 554 patients had a normal G-banded karyotype. In the latter group, a genomic imbalance was detected by HR-CGH in 40 patients (7.2%): 29 deletions, 3 duplications, 4 unbalanced translocations, and 4 occult trisomy mosaicisms. When microarray-based comparative genomic hybridisation (array-CGH) became available, all HR-CGH-positive samples were also investigated by 1 Mb resolution array-CGH for more precise mapping. From the 514 patients with normal HR-CGH findings, a subset of 20 patients with particularly high suspicion of having a chromosomal imbalance was selected for array-CGH. In four of them (20%), an imbalance was detected: three deletions and one duplication. Of note, 73 out of the 80 array-CGH mapped patients had a de novo chromosomal rearrangement (91%). Taken together, this work provides phenotype-genotype information on 80 patients with minor and cryptic chromosomal imbalances.

  15. Fabrication of large-sized two-dimensional ordered surface array with well-controlled structure via colloidal particle lithography.

    PubMed

    Meng, Xiaohui; Zhang, Xinping; Ye, Lei; Qiu, Dong

    2014-06-17

    Epoxy resin coated glass slides were used for colloidal particle lithography, in order to prepare well-defined 2D surface arrays. Upon the assistance of a large-sized 2D colloidal single crystal as template, centimeter-sized ordered surface arrays of bowl-like units were obtained. Systematic studies revealed that the parameters of obtained surface arrays could be readily controlled by some operational factors, such as temperature, epoxy resin layer thickness, and template particle size. With epoxy resin substituting for normal linear polymer, the height/diameter ratio of bowls in the formed surface arrays can be largely increased. With further reactive plasma etching, the parameters of ordered surface arrays could be finely tuned through controlling etching time. This study provides a facile way to prepare large-sized 2D surface arrays with tunable parameters.

  16. Optimal deployment of attentional gain during fine discriminations.

    PubMed

    Scolari, Miranda; Byers, Anna; Serences, John T

    2012-05-30

    Most models assume that top-down attention enhances the gain of sensory neurons tuned to behaviorally relevant stimuli (on-target gain). However, theoretical work suggests that when targets and distracters are highly similar, attention should enhance the gain of neurons that are tuned away from the target, because these neurons better discriminate neighboring features (off-target gain). While it is established that off-target neurons support difficult fine discriminations, it is unclear if top-down attentional gain can be optimally applied to informative off-target sensory neurons or if gain is always applied to on-target neurons, regardless of task demands. To test the optimality of attentional gain in human visual cortex, we used functional magnetic resonance imaging and an encoding model to estimate the response profile across a set of hypothetical orientation-selective channels during a difficult discrimination task. The results suggest that top-down attention can adaptively modulate off-target neural populations, but only when the discriminanda are precisely specified in advance. Furthermore, logistic regression revealed that activation levels in off-target orientation channels predicted behavioral accuracy on a trial-by-trial basis. Overall, these data suggest that attention does not only increase the gain of sensory-evoked responses, but may bias population response profiles in an optimal manner that respects both the tuning properties of sensory neurons and the physical characteristics of the stimulus array.

  17. Optimal deployment of attentional gain during fine discriminations

    PubMed Central

    Scolari, Miranda; Byers, Anna; Serences, John T.

    2012-01-01

    Most models assume that top-down attention enhances the gain of sensory neurons tuned to behaviorally-relevant stimuli (on-target gain). However, theoretical work suggests that when targets and distracters are highly similar, attention should enhance the gain of neurons that are tuned away from the target, because these neurons better discriminate neighboring features (off-target gain). While it is established that off-target neurons support difficult fine discriminations, it is unclear if top-down attentional gain can be optimally applied to informative off-target sensory neurons or if gain is always applied to on-target neurons, irrespective of task demands. To test the optimality of attentional gain in human visual cortex, we used fMRI and an encoding model to estimate the response profile across a set of hypothetical orientation-selective channels during a difficult discrimination task. The results suggest that top-down attention can adaptively modulate off-target neural populations, but only when the discriminanda are precisely specified in advance. Furthermore, logistic regression revealed that activation levels in off-target orientation channels predicted behavioral accuracy on a trial-by-trial basis. Overall, these data suggest that attention does not always increase the gain of sensory-evoked responses, but instead may bias population response profiles in an optimal manner that respects both the tuning properties of sensory neurons and the physical characteristics of the stimulus array. PMID:22649250

  18. An optimal tuning strategy for tidal turbines

    NASA Astrophysics Data System (ADS)

    Vennell, Ross

    2016-11-01

    Tuning wind and tidal turbines is critical to maximizing their power output. Adopting a wind turbine tuning strategy of maximizing the output at any given time is shown to be an extremely poor strategy for large arrays of tidal turbines in channels. This `impatient-tuning strategy' results in far lower power output, much higher structural loads and greater environmental impacts due to flow reduction than an existing `patient-tuning strategy' which maximizes the power output averaged over the tidal cycle. This paper presents a `smart patient tuning strategy', which can increase array output by up to 35% over the existing strategy. This smart strategy forgoes some power generation early in the half tidal cycle in order to allow stronger flows to develop later in the cycle. It extracts enough power from these stronger flows to produce more power from the cycle as a whole than the existing strategy. Surprisingly, the smart strategy can often extract more power without increasing maximum structural loads on the turbines, while also maintaining stronger flows along the channel. This paper also shows that, counterintuitively, for some tuning strategies imposing a cap on turbine power output to limit loads can increase a turbine's average power output.

  19. An optimal tuning strategy for tidal turbines.

    PubMed

    Vennell, Ross

    2016-11-01

    Tuning wind and tidal turbines is critical to maximizing their power output. Adopting a wind turbine tuning strategy of maximizing the output at any given time is shown to be an extremely poor strategy for large arrays of tidal turbines in channels. This 'impatient-tuning strategy' results in far lower power output, much higher structural loads and greater environmental impacts due to flow reduction than an existing 'patient-tuning strategy' which maximizes the power output averaged over the tidal cycle. This paper presents a 'smart patient tuning strategy', which can increase array output by up to 35% over the existing strategy. This smart strategy forgoes some power generation early in the half tidal cycle in order to allow stronger flows to develop later in the cycle. It extracts enough power from these stronger flows to produce more power from the cycle as a whole than the existing strategy. Surprisingly, the smart strategy can often extract more power without increasing maximum structural loads on the turbines, while also maintaining stronger flows along the channel. This paper also shows that, counterintuitively, for some tuning strategies imposing a cap on turbine power output to limit loads can increase a turbine's average power output.

  20. Efficient receiver tuning using differential evolution strategies

    NASA Astrophysics Data System (ADS)

    Wheeler, Caleb H.; Toland, Trevor G.

    2016-08-01

    Differential evolution (DE) is a powerful and computationally inexpensive optimization strategy that can be used to search an entire parameter space or to converge quickly on a solution. The Kilopixel Array Pathfinder Project (KAPPa) is a heterodyne receiver system delivering 5 GHz of instantaneous bandwidth in the tuning range of 645-695 GHz. The fully automated KAPPa receiver test system finds optimal receiver tuning using performance feedback and DE. We present an adaptation of DE for use in rapid receiver characterization. The KAPPa DE algorithm is written in Python 2.7 and is fully integrated with the KAPPa instrument control, data processing, and visualization code. KAPPa develops the technologies needed to realize heterodyne focal plane arrays containing 1000 pixels. Finding optimal receiver tuning by investigating large parameter spaces is one of many challenges facing the characterization phase of KAPPa. This is a difficult task via by-hand techniques. Characterizing or tuning in an automated fashion without need for human intervention is desirable for future large scale arrays. While many optimization strategies exist, DE is ideal for time and performance constraints because it can be set to converge to a solution rapidly with minimal computational overhead. We discuss how DE is utilized in the KAPPa system and discuss its performance and look toward the future of 1000 pixel array receivers and consider how the KAPPa DE system might be applied.

  1. Water transport control in carbon nanotube arrays

    PubMed Central

    2014-01-01

    Based on a recent scaling law of the water mobility under nanoconfined conditions, we envision novel strategies for precise modulation of water diffusion within membranes made of carbon nanotube arrays (CNAs). In a first approach, the water diffusion coefficient D may be tuned by finely controlling the size distribution of the pore size. In the second approach, D can be varied at will by means of externally induced electrostatic fields. Starting from the latter strategy, switchable molecular sieves are proposed, where membranes are properly designed with sieving and permeation features that can be dynamically activated/deactivated. Areas where a precise control of water transport properties is beneficial range from energy and environmental engineering up to nanomedicine. PMID:25313305

  2. Fine Arts.

    ERIC Educational Resources Information Center

    Danzer, Gerald A.; Newman, Mark

    1992-01-01

    Discusses the use of fine arts as sources to enrich the study of history. Suggests that such works will serve as barometers of change, examples of cross-cultural influences, and political messages. Includes suggestions of works and artists from different historic periods. (DK)

  3. Fine Arts.

    ERIC Educational Resources Information Center

    Danzer, Gerald A.; Newman, Mark

    1992-01-01

    Discusses the use of fine arts as sources to enrich the study of history. Suggests that such works will serve as barometers of change, examples of cross-cultural influences, and political messages. Includes suggestions of works and artists from different historic periods. (DK)

  4. Tuning of Pectin Methylesterification

    PubMed Central

    Sénéchal, Fabien; L'Enfant, Mélanie; Domon, Jean-Marc; Rosiau, Emeline; Crépeau, Marie-Jeanne; Surcouf, Ogier; Esquivel-Rodriguez, Juan; Marcelo, Paulo; Mareck, Alain; Guérineau, François; Kim, Hyung-Rae; Mravec, Jozef; Bonnin, Estelle; Jamet, Elisabeth; Kihara, Daisuke; Lerouge, Patrice; Ralet, Marie-Christine; Pelloux, Jérôme; Rayon, Catherine

    2015-01-01

    Pectin methylesterases (PMEs) catalyze the demethylesterification of homogalacturonan domains of pectin in plant cell walls and are regulated by endogenous pectin methylesterase inhibitors (PMEIs). In Arabidopsis dark-grown hypocotyls, one PME (AtPME3) and one PMEI (AtPMEI7) were identified as potential interacting proteins. Using RT-quantitative PCR analysis and gene promoter::GUS fusions, we first showed that AtPME3 and AtPMEI7 genes had overlapping patterns of expression in etiolated hypocotyls. The two proteins were identified in hypocotyl cell wall extracts by proteomics. To investigate the potential interaction between AtPME3 and AtPMEI7, both proteins were expressed in a heterologous system and purified by affinity chromatography. The activity of recombinant AtPME3 was characterized on homogalacturonans (HGs) with distinct degrees/patterns of methylesterification. AtPME3 showed the highest activity at pH 7.5 on HG substrates with a degree of methylesterification between 60 and 80% and a random distribution of methyl esters. On the best HG substrate, AtPME3 generates long non-methylesterified stretches and leaves short highly methylesterified zones, indicating that it acts as a processive enzyme. The recombinant AtPMEI7 and AtPME3 interaction reduces the level of demethylesterification of the HG substrate but does not inhibit the processivity of the enzyme. These data suggest that the AtPME3·AtPMEI7 complex is not covalently linked and could, depending on the pH, be alternately formed and dissociated. Docking analysis indicated that the inhibition of AtPME3 could occur via the interaction of AtPMEI7 with a PME ligand-binding cleft structure. All of these data indicate that AtPME3 and AtPMEI7 could be partners involved in the fine tuning of HG methylesterification during plant development. PMID:26183897

  5. Model-independent particle accelerator tuning

    SciTech Connect

    Scheinker, Alexander; Pang, Xiaoying; Rybarcyk, Larry

    2013-10-21

    We present a new model-independent dynamic feedback technique, rotation rate tuning, for automatically and simultaneously tuning coupled components of uncertain, complex systems. The main advantages of the method are: 1) It has the ability to handle unknown, time-varying systems, 2) It gives known bounds on parameter update rates, 3) We give an analytic proof of its convergence and its stability, and 4) It has a simple digital implementation through a control system such as the Experimental Physics and Industrial Control System (EPICS). Because this technique is model independent it may be useful as a real-time, in-hardware, feedback-based optimization scheme for uncertain and time-varying systems. In particular, it is robust enough to handle uncertainty due to coupling, thermal cycling, misalignments, and manufacturing imperfections. As a result, it may be used as a fine-tuning supplement for existing accelerator tuning/control schemes. We present multi-particle simulation results demonstrating the scheme’s ability to simultaneously adaptively adjust the set points of twenty two quadrupole magnets and two RF buncher cavities in the Los Alamos Neutron Science Center Linear Accelerator’s transport region, while the beam properties and RF phase shift are continuously varying. The tuning is based only on beam current readings, without knowledge of particle dynamics. We also present an outline of how to implement this general scheme in software for optimization, and in hardware for feedback-based control/tuning, for a wide range of systems.

  6. Carbon nanotube array: a new MIP platform.

    PubMed

    Choong, Chwee-Lin; Bendall, James S; Milne, William I

    2009-11-15

    Here we demonstrate that a free-standing carbon nanotube (CNT) array can be used as a large surface area and high porosity 3D platform for molecular imprinted polymer (MIP), especially for surface imprinting. The thickness of polymer grafted around each CNT can be fine-tuned to imprint different sizes of target molecules, and yet it can be thin enough to expose every imprint site to the target molecules in solution without sacrificing the capacity of binding sites. The performance of this new CNT-MIP architecture was first assessed with a caffeine-imprinted polypyrrole (PPy) coating on two types of CNT arrays: sparse and dense CNTs. Real-time pulsed amperometric detection was used to study the rebinding of the caffeine molecules onto these CNT-MIPPy sensors. The dense CNT-MIPPy sensor presented the highest sensitivity, about 15 times better when compared to the conventional thin film, whereas an improvement of 3.6 times was recorded on the sparse CNT. However, due to the small tube-to-tube spacing in the dense CNT array, electrode fouling was observed during the detection of concentrated caffeine in phosphate buffer solution. A new I-V characterization method using pulsed amperometry was introduced to investigate the electrical characterization of these new devices. The resistance value derived from the I-V plot provides insight into the electrical conductivity of the CNT transducer and also the effective surface area for caffeine imprinting.

  7. Tuning Metamaterials by using Amorphous Magnetic Microwires.

    PubMed

    Lopez-Dominguez, V; Garcia, M A; Marin, P; Hernando, A

    2017-08-24

    In this work, we demonstrate theoretically and experimentally the possibility of tuning the electromagnetic properties of metamaterials with magnetic fields by incorporating amorphous magnetic microwires. The large permeability of these wires at microwave frequencies allows tuning the resonance of the metamaterial by using magnetic fields of the order of tens of Oe. We describe here the physical basis of the interaction between a prototypical magnetic metamaterial with magnetic microwires and electromagnetic waves plus providing detailed calculations and experimental results for the case of an array of Split Ring Resonators with Co-based microwires.

  8. Thiadiazoloquinoxalines: tuning physical properties through smart synthesis.

    PubMed

    Dallos, Timea; Hamburger, Manuel; Baumgarten, Martin

    2011-04-15

    The synthesis of π-conjugated acceptors based on thiadiazoloquinoxaline (TQ) derivatives is described. Apart from reporting on the functionalization of the TQ core, the influence of the substituents was studied by UV-vis absorption and emission spectroscopy, cyclic voltammetry measurements, and DFT calculations. By changing the donor as well as the π-spacer, a fine-tuning of the photo- and electrochemical properties was achieved.

  9. PERI auto-tuning.

    SciTech Connect

    Chame, J.; Chen, C.; Dongarra, J.; Hall, M.; Hollingsworth, J. K.; Hovland, P.; Moore, S.; Seymour, K.; Shin, J.; Tiwari, A.; Williams, S.; You, H.; Bailey, D. H.

    2008-01-01

    The enormous and growing complexity of today's high-end systems has increased the already significant challenges of obtaining high performance on equally complex scientific applications. Application scientists are faced with a daunting challenge in tuning their codes to exploit performance-enhancing architectural features. The Performance Engineering Research Institute (PERI) is working toward the goal of automating portions of the performance tuning process. This paper describes PERI's overall strategy for auto-tuning tools and recent progress in both building auto-tuning tools and demonstrating their success on kernels, some taken from large-scale applications.

  10. Simultaneous multispectral framing infrared camera using an embedded diffractive optical lenslet array

    NASA Astrophysics Data System (ADS)

    Hinnrichs, Michele

    2011-06-01

    Recent advances in micro-optical element fabrication using gray scale technology have opened up the opportunity to create simultaneous multi-spectral imaging with fine structure diffractive lenses. This paper will discuss an approach that uses diffractive optical lenses configured in an array (lenslet array) and placed in close proximity to the focal plane array which enables a small compact simultaneous multispectral imaging camera [1]. The lenslet array is designed so that all lenslets have a common focal length with each lenslet tuned for a different wavelength. The number of simultaneous spectral images is determined by the number of individually configured lenslets in the array. The number of spectral images can be increased by a factor of 2 when using it with a dual-band focal plane array (MWIR/LWIR) by exploiting multiple diffraction orders. In addition, modulation of the focal length of the lenslet array with piezoelectric actuation will enable spectral bin fill-in allowing additional spectral coverage while giving up simultaneity. Different lenslet array spectral imaging concept designs are presented in this paper along with a unique concept for prefiltering the radiation focused on the detector. This approach to spectral imaging has applications in the detection of chemical agents in both aerosolized form and as a liquid on a surface. It also can be applied to the detection of weaponized biological agent and IED detection in various forms from manufacturing to deployment and post detection during forensic analysis.

  11. Ecotin-Like ISP of L. major Promastigotes Fine-Tunes Macrophage Phagocytosis by Limiting the Pericellular Release of Bradykinin from Surface-Bound Kininogens: A Survival Strategy Based on the Silencing of Proinflammatory G-Protein Coupled Kinin B2 and B1 Receptors

    PubMed Central

    Svensjö, Erik; Vellasco, Lucas; Scharfstein, Julio

    2014-01-01

    Inhibitors of serine peptidases (ISPs) expressed by Leishmania major enhance intracellular parasitism in macrophages by targeting neutrophil elastase (NE), a serine protease that couples phagocytosis to the prooxidative TLR4/PKR pathway. Here we investigated the functional interplay between ISP-expressing L. major and the kallikrein-kinin system (KKS). Enzymatic assays showed that NE inhibitor or recombinant ISP-2 inhibited KKS activation in human plasma activated by dextran sulfate. Intravital microscopy in the hamster cheek pouch showed that topically applied L. major promastigotes (WT and Δisp2/3 mutants) potently induced plasma leakage through the activation of bradykinin B2 receptors (B2R). Next, using mAbs against kininogen domains, we showed that these BK-precursor proteins are sequestered by L. major promastigotes, being expressed at higher % in the Δisp2/3 mutant population. Strikingly, analysis of the role of kinin pathway in the phagocytic uptake of L. major revealed that antagonists of B2R or B1R reversed the upregulated uptake of Δisp2/3 mutants without inhibiting macrophage internalization of WT L. major. Collectively, our results suggest that L. major ISP-2 fine-tunes macrophage phagocytosis by inhibiting the pericellular release of proinflammatory kinins from surface bound kininogens. Ongoing studies should clarify whether L. major ISP-2 subverts TLR4/PKR-dependent prooxidative responses of macrophages by preventing activation of G-protein coupled B2R/B1R. PMID:25294952

  12. Commentary on: "Redirecting abiraterone metabolism to fine-tune prostate cancer anti-androgen therapy." Li Z, Alyamani M, Li J, Rogacki K, Abazeed M, Upadhyay SK, Balk SP, Taplin ME, Auchus RJ, Sharifi N. Nature. 2016 May 25;533(7604):547-51.

    PubMed

    Lee, Byron H

    2017-09-01

    Abiraterone blocks androgen synthesis and prolongs survival in patients with castration-resistant prostate cancer, which is otherwise driven by intratumoral androgen synthesis. Abiraterone is metabolized in patients to Δ(4)-abiraterone (D4A), which has even greater antitumour activity and is structurally similar to endogenous steroidal 5α-reductase substrates, such as testosterone. Here, we show that D4A is converted to at least three 5α-reduced and three 5β-reduced metabolites in human serum. The initial 5α-reduced metabolite, 3-keto-5α-abiraterone, is present at higher concentrations than D4A in patients with prostate cancer taking abiraterone, and is an androgen receptor agonist, which promotes prostate cancer progression. In a clinical trial of abiraterone alone, followed by abiraterone plus dutasteride (a 5α-reductase inhibitor), 3-keto-5α-abiraterone and downstream metabolites were depleted by the addition of dutasteride, while D4A concentrations rose, showing that dutasteride effectively blocks production of a tumor-promoting metabolite and permits D4A accumulation. Furthermore, dutasteride did not deplete the three 5β-reduced metabolites, which were also clinically detectable, demonstrating the specific biochemical effects of pharmacological 5α-reductase inhibition on abiraterone metabolism. Our findings suggest a previously unappreciated and biochemically specific method of clinically fine-tuning abiraterone metabolism to optimize therapy. Copyright © 2017 Elsevier Inc. All rights reserved.

  13. Natural tuning: towards a proof of concept

    NASA Astrophysics Data System (ADS)

    Dubovsky, Sergei; Gorbenko, Victor; Mirbabayi, Mehrdad

    2013-09-01

    The cosmological constant problem and the absence of new natural physics at the electroweak scale, if confirmed by the LHC, may either indicate that the nature is fine-tuned or that a refined notion of naturalness is required. We construct a family of toy UV complete quantum theories providing a proof of concept for the second possibility. Low energy physics is described by a tuned effective field theory, which exhibits relevant interactions not protected by any symmetries and separated by an arbitrary large mass gap from the new "gravitational" physics, represented by a set of irrelevant operators. Nevertheless, the only available language to describe dynamics at all energy scales does not require any fine-tuning. The interesting novel feature of this construction is that UV physics is not described by a fixed point, but rather exhibits asymptotic fragility. Observation of additional unprotected scalars at the LHC would be a smoking gun for this scenario. Natural tuning also favors TeV scale unification.

  14. Tuning innate immunity by translation.

    PubMed

    Rauscher, Robert; Ignatova, Zoya

    2015-12-01

    In multicellular organisms, the epithelia is a contact surface with the surrounding environment and is exposed to a variety of adverse biotic (pathogenic) and abiotic (chemical) factors. Multi-layered pathways that operate on different time scales have evolved to preserve cellular integrity and elicit stress-specific response. Several stress-response programs are activated until a complete elimination of the stress is achieved. The innate immune response, which is triggered by pathogenic invasion, is rather harmful when active over a prolonged time, thus the response follows characteristic oscillatory trajectories. Here, we review different translation programs that function to precisely fine-tune the time at which various components of the innate immune response dwell between active and inactive. We discuss how different pro-inflammatory pathways are co-ordinated to temporally offset single reactions and to achieve an optimal balance between fighting pathogens and being less harmful for healthy cells.

  15. Nanostructured gold architectures formed through high pressure-driven sintering of spherical nanoparticle arrays.

    PubMed

    Wu, Huimeng; Bai, Feng; Sun, Zaicheng; Haddad, Raid E; Boye, Daniel M; Wang, Zhongwu; Huang, Jian Yu; Fan, Hongyou

    2010-09-22

    We have demonstrated pressure-directed assembly for preparation of a new class of chemically and mechanically stable gold nanostructures through high pressure-driven sintering of nanoparticle assemblies at room temperature. We show that under a hydrostatic pressure field, the unit cell dimension of a 3D ordered nanoparticle array can be reversibly manipulated allowing fine-tuning of the interparticle separation distance. In addition, 3D nanostructured gold architecture can be formed through high pressure-induced nanoparticle sintering. This work opens a new pathway for engineering and fabrication of different metal nanostructured architectures.

  16. Wavelength tunable, 264 J laser diode array for 10 Hz/1ms Yb:YAG pumping

    NASA Astrophysics Data System (ADS)

    Chanteloup, J.-C.; Albach, D.; Assémat, F.; Bahbah, S.; Bourdet, G.; Piatti, P.; Pluvinage, M.; Vincent, B.; LeTouzé, G.; Mattern, T.; Biesenbach, J.; Müntz, H.; Noeske, A.; Venohr, R.

    2008-05-01

    The Lucia [1,2] Laser program, under development at the LULI laboratory, aims at delivering a 1030 nm, 100J, 10 Hz, 10 ns pulse train. The two laser heads used in the amplification stage relies on water-cooled mm-thick Yb:YAG disks, each of them pumped by a 34×13 cm2 Laser Diode Array (LDA). For each LDA, the 88 QCW diodes stacks manufactured by DILAS GmbH will be tiled in an 8×11 arrangement. Fine wavelength tuning is performed through bias current adjustment, water temperature control and conductivity adjustment. Wavelength homogeneity experimental verification has been validated.

  17. Tuning micropillar cavity birefringence by laser induced surface defects

    SciTech Connect

    Bonato, Cristian; Ding Dapeng; Gudat, Jan; Exter, Martin P. van; Thon, Susanna; Kim, Hyochul; Petroff, Pierre M.; Bouwmeester, Dirk

    2009-12-21

    We demonstrate a technique to tune the optical properties of micropillar cavities by creating small defects on the sample surface near the cavity region with an intense focused laser beam. Such defects modify strain in the structure, changing the birefringence in a controllable way. We apply the technique to make the fundamental cavity mode polarization-degenerate and to fine tune the overall mode frequencies, as needed for applications in quantum information science.

  18. Tuned borehole gravity gradiometer

    SciTech Connect

    Lautzenhiser, T.V.; Nekut, A.G. Jr.

    1986-04-15

    A tuned borehole gravity gradiometer is described for detecting variations in gravity gradient which consists of: a suspended dipole mass system having symmetrically distributed dipole masses and suspension means for suspending the dipole masses such that the gravity gradient to be measured produces an angular displacement about a rotation axis of the dipole mass system from a reference position; and tuning means with the dipole mass system for selectively varying the sensitivity to angular displacements with respect to the rotation axis of the dipole mass system to variations in gravity gradient, wherein the tuning means includes means for selectively varying the metacentric height of the dipole mass system.

  19. Active impedance metasurface with full 360° reflection phase tuning

    PubMed Central

    Zhu, Bo O.; Zhao, Junming; Feng, Yijun

    2013-01-01

    Impedance metasurface is composed of electrical small scatters in two dimensional plane, of which the surface impedance can be designed to produce desired reflection phase. Tunable reflection phase can be achieved by incorporating active element into the scatters, but the tuning range of the reflection phase is limited. In this paper, an active impedance metasurface with full 360° reflection phase control is presented to remove the phase tuning deficiency in conventional approach. The unit cell of the metasurface is a multiple resonance structure with two resonance poles and one resonance zero, capable of providing 360° reflection phase variation and active tuning within a finite frequency band. Linear reflection phase tuning can also be obtained. Theoretical analysis and simulation are presented and validated by experiment at microwave frequency. The proposed approach can be applied to many cases where fine and full phase tuning is needed, such as beam steering in reflectarray antennas. PMID:24162366

  20. Prediction of fine-tuned promoter activity from DNA sequence

    PubMed Central

    Siwo, Geoffrey; Rider, Andrew; Tan, Asako; Pinapati, Richard; Emrich, Scott; Chawla, Nitesh; Ferdig, Michael

    2016-01-01

    The quantitative prediction of transcriptional activity of genes using promoter sequence is fundamental to the engineering of biological systems for industrial purposes and understanding the natural variation in gene expression. To catalyze the development of new algorithms for this purpose, the Dialogue on Reverse Engineering Assessment and Methods (DREAM) organized a community challenge seeking predictive models of promoter activity given normalized promoter activity data for 90 ribosomal protein promoters driving expression of a fluorescent reporter gene. By developing an unbiased modeling approach that performs an iterative search for predictive DNA sequence features using the frequencies of various k-mers, inferred DNA mechanical properties and spatial positions of promoter sequences, we achieved the best performer status in this challenge. The specific predictive features used in the model included the frequency of the nucleotide G, the length of polymeric tracts of T and TA, the frequencies of 6 distinct trinucleotides and 12 tetranucleotides, and the predicted protein deformability of the DNA sequence. Our method accurately predicted the activity of 20 natural variants of ribosomal protein promoters (Spearman correlation r = 0.73) as compared to 33 laboratory-mutated variants of the promoters (r = 0.57) in a test set that was hidden from participants. Notably, our model differed substantially from the rest in 2 main ways: i) it did not explicitly utilize transcription factor binding information implying that subtle DNA sequence features are highly associated with gene expression, and ii) it was entirely based on features extracted exclusively from the 100 bp region upstream from the translational start site demonstrating that this region encodes much of the overall promoter activity. The findings from this study have important implications for the engineering of predictable gene expression systems and the evolution of gene expression in naturally occurring biological systems. PMID:27347373

  1. Prediction of fine-tuned promoter activity from DNA sequence.

    PubMed

    Siwo, Geoffrey; Rider, Andrew; Tan, Asako; Pinapati, Richard; Emrich, Scott; Chawla, Nitesh; Ferdig, Michael

    2016-01-01

    The quantitative prediction of transcriptional activity of genes using promoter sequence is fundamental to the engineering of biological systems for industrial purposes and understanding the natural variation in gene expression. To catalyze the development of new algorithms for this purpose, the Dialogue on Reverse Engineering Assessment and Methods (DREAM) organized a community challenge seeking predictive models of promoter activity given normalized promoter activity data for 90 ribosomal protein promoters driving expression of a fluorescent reporter gene. By developing an unbiased modeling approach that performs an iterative search for predictive DNA sequence features using the frequencies of various k-mers, inferred DNA mechanical properties and spatial positions of promoter sequences, we achieved the best performer status in this challenge. The specific predictive features used in the model included the frequency of the nucleotide G, the length of polymeric tracts of T and TA, the frequencies of 6 distinct trinucleotides and 12 tetranucleotides, and the predicted protein deformability of the DNA sequence. Our method accurately predicted the activity of 20 natural variants of ribosomal protein promoters (Spearman correlation r = 0.73) as compared to 33 laboratory-mutated variants of the promoters (r = 0.57) in a test set that was hidden from participants. Notably, our model differed substantially from the rest in 2 main ways: i) it did not explicitly utilize transcription factor binding information implying that subtle DNA sequence features are highly associated with gene expression, and ii) it was entirely based on features extracted exclusively from the 100 bp region upstream from the translational start site demonstrating that this region encodes much of the overall promoter activity. The findings from this study have important implications for the engineering of predictable gene expression systems and the evolution of gene expression in naturally occurring biological systems.

  2. Musicians have fine-tuned neural distinction of speech syllables

    PubMed Central

    Parbery-Clark, Alexandra; Tierney, Adam; Strait, Dana L.; Kraus, Nina

    2012-01-01

    One of the benefits musicians derive from their training is an increased ability to detect small differences between sounds. Here, we asked whether musicians’ experience discriminating sounds on the basis of small acoustic differences confers advantages in the subcortical differentiation of closely-related speech sounds (e.g., /ba/ and /ga/), distinguishable only by their harmonic spectra (i.e., their second formant trajectories). Although the second formant is particularly important for distinguishing stop consonants, auditory brainstem neurons do not phase-lock to its frequency range (above 1000 Hz). Instead, brainstem nuclei convert this high-frequency content into neural response timing differences. As such, speech tokens with higher formant frequencies elicit earlier brainstem responses than those with lower formant frequencies. By measuring the degree to which subcortical response timing differs to the speech syllables /ba/, /da/, and /ga/ in adult musicians and nonmusicians, we reveal that musicians demonstrate enhanced subcortical discrimination of closely related speech sounds. Furthermore, the extent of subcortical consonant discrimination correlates with speech-in-noise perception. Taken together, these findings show a musician enhancement for the neural processing of speech and reveal a biological mechanism contributing to musicians’ enhanced speech perception. PMID:22634507

  3. Fine tuning by miRNAs in development

    NASA Astrophysics Data System (ADS)

    McHale, Peter; Levine, Erel; Levine, Herbert

    2007-03-01

    The unique role played by microRNA in a developing embryo is a topic of much current research interest. One possibility is that microRNA diffuse within a developing tissue, acting as communicators between different cells. Here we pursue this possibility in two different contexts. The first case occurs when the transcription profiles of the microRNA and its target are spatially anticorrelated, as for example is the case in the iab4-Ubx system in fly. Conversely, in the second context the two transcription profiles are correlated in space, as may be the case for the mir10-Hoxb4 system in mouse. In each context we identify a major function for a mobile miRNA. In the first, miRNA serve to induce an all-or-nothing response of the mRNA profile to its morphogen by generating a sharp boundary between domains of high and (ultimately) low target expression. In the second, miRNA amplify polarity in the target expression pattern by removing residual mRNAs. Importantly, our model predicts that these two functions require very different type of diffusion. While our results are highly quantitative, we propose ways of realizing them in experiments, taking into account limitations of standard experimental techniques.

  4. Fine tuning of graphene-metal adhesion by surface alloying.

    PubMed

    Alfè, D; Pozzo, M; Miniussi, E; Günther, S; Lacovig, P; Lizzit, S; Larciprete, R; Santos Burgos, B; Menteş, T O; Locatelli, A; Baraldi, A

    2013-01-01

    We show that bimetallic surface alloying provides a viable route for governing the interaction between graphene and metal through the selective choice of the elemental composition of the surface alloy. This concept is illustrated by an experimental and theoretical characterization of the properties of graphene on a model PtRu surface alloy on Ru(0001), with a concentration of Pt atoms in the first layer between 0 and 50%. The progressive increase of the Pt content determines the gradual detachment of graphene from the substrate, which results from the modification of the carbon orbital hybridization promoted by Pt. Alloying is also found to affect the morphology of graphene, which is strongly corrugated on bare Ru, but becomes flat at a Pt coverage of 50%. The method here proposed can be readily extended to several supports, thus opening the way to the conformal growth of graphene on metals and to a full tunability of the graphene-substrate interaction.

  5. Fine Tuning Cell Migration by a Disintegrin and Metalloproteinases

    PubMed Central

    Theodorou, K.

    2017-01-01

    Cell migration is an instrumental process involved in organ development, tissue homeostasis, and various physiological processes and also in numerous pathologies. Both basic cell migration and migration towards chemotactic stimulus consist of changes in cell polarity and cytoskeletal rearrangement, cell detachment from, invasion through, and reattachment to their neighboring cells, and numerous interactions with the extracellular matrix. The different steps of immune cell, tissue cell, or cancer cell migration are tightly coordinated in time and place by growth factors, cytokines/chemokines, adhesion molecules, and receptors for these ligands. This review describes how a disintegrin and metalloproteinases interfere with several steps of cell migration, either by proteolytic cleavage of such molecules or by functions independent of proteolytic activity. PMID:28260841

  6. Fine Tuning Cell Migration by a Disintegrin and Metalloproteinases.

    PubMed

    Dreymueller, D; Theodorou, K; Donners, M; Ludwig, A

    2017-01-01

    Cell migration is an instrumental process involved in organ development, tissue homeostasis, and various physiological processes and also in numerous pathologies. Both basic cell migration and migration towards chemotactic stimulus consist of changes in cell polarity and cytoskeletal rearrangement, cell detachment from, invasion through, and reattachment to their neighboring cells, and numerous interactions with the extracellular matrix. The different steps of immune cell, tissue cell, or cancer cell migration are tightly coordinated in time and place by growth factors, cytokines/chemokines, adhesion molecules, and receptors for these ligands. This review describes how a disintegrin and metalloproteinases interfere with several steps of cell migration, either by proteolytic cleavage of such molecules or by functions independent of proteolytic activity.

  7. Spanish "fine tuning" of language to describe depression and anxiety.

    PubMed

    Noguera, Antonio; Centeno, Carlos; Carvajal, Ana; Tejedor, María Angustias Portela; Urdiroz, Juliana; Martínez, Marina

    2009-08-01

    On screening tools for emotional distress, the terms "depression" and "anxiety" are commonly used for patients with advanced cancer. However, these terms could have negative connotations in Spanish such that cultural and unexpected differences in perception may invalidate or skew the results of the screening if the best terms are not chosen. The goal of this study was to determine the best expression that can be used to explore anxiety and depression in Spanish. A prospective study of 100 Spanish-speaking patients was performed. Spanish patients with cancer completed the Hospital Anxiety and Depression Scale (HADS) and six Verbal Numerical Scales (VNS) exploring the level of anxiety using the terms ansioso (anxious), nervioso (nervous), or intranquilo (uneasy/disquiet), and the level of depression using the terms deprimido (depressed), desanimado (discouraged), or triste (sad). The correlation, sensitivity, and specificity for all the VNS and HADS (8 and 11 cutoff points) were analyzed. The correlation (Spearman rho) between HADS and the anxiety VNS was r = 0.557 using "anxious"; r = 0.603 using "nervous"; and r = 0.594 using "uneasy." The correlation for the depression VNS was r = 0.662 using "depression"; r = 0.759 using "discouraged" and r = 0.596 using "sad"; alpha < 0.001 was used in all VNS. A cutoff point of 4 of 10 for any term used to explore anxiety achieved the best levels for sensitivity (0.80) and specificity (0.70). The term "discouraged" with a cutoff point of 4 of 10 shows a sensitivity of 0.89, a specificity of 0.84, as well as a predictive positive value of 0.77 and a negative value of 0.93. In Spanish, the term desanimado seems to be more suitable in screening for depression. Alternate terms could be used to explore anxiety in Spanish. Exploring depression with simple questions in Spanish achieves greater accuracy than the same approach to exploring anxiety.

  8. Silicon quantum dots: fine-tuning to maturity.

    PubMed

    Morello, Andrea

    2015-12-18

    Quantum dots in semiconductor heterostructures provide one of the most flexible platforms for the study of quantum phenomena at the nanoscale. The surging interest in using quantum dots for quantum computation is forcing researchers to rethink fabrication and operation methods, to obtain highly tunable dots in spin-free host materials, such as silicon. Borselli and colleagues report in Nanotechnology the fabrication of a novel Si/SiGe double quantum dot device, which combines an ultra-low disorder Si/SiGe accumulation-mode heterostructure with a stack of overlapping control gates, ensuring tight confining potentials and exquisite tunability. This work signals the technological maturity of silicon quantum dots, and their readiness to be applied to challenging projects in quantum information science.

  9. tRNA concentration fine tunes protein solubility.

    PubMed

    Fedyunin, Ivan; Lehnhardt, Lothar; Böhmer, Nadine; Kaufmann, Paul; Zhang, Gong; Ignatova, Zoya

    2012-09-21

    Clusters of codons pairing to low-abundance tRNAs synchronize the translation with co-translational folding of single domains in multidomain proteins. Although proven with some examples, the impact of the ribosomal speed on the folding and solubility on a global, cell-wide level remains elusive. Here we show that upregulation of three low-abundance tRNAs in Escherichia coli increased the aggregation propensity of several cellular proteins as a result of an accelerated elongation rate. Intriguingly, alterations in the concentration of the natural tRNA pool compromised the solubility of various chaperones consequently rendering the solubility of some chaperone-dependent proteins.

  10. Novel players fine-tune plant trade-offs.

    PubMed

    Gimenez-Ibanez, Selena; Boter, Marta; Solano, Roberto

    2015-01-01

    Jasmonates (JAs) are essential signalling molecules that co-ordinate the plant response to biotic and abiotic challenges, as well as co-ordinating several developmental processes. Huge progress has been made over the last decade in understanding the components and mechanisms that govern JA perception and signalling. The bioactive form of the hormone, (+)-7-iso-jasmonyl-L-isoleucine (JA-Ile), is perceived by the COI1-JAZ co-receptor complex. JASMONATE ZIM DOMAIN (JAZ) proteins also act as direct repressors of transcriptional activators such as MYC2. In the emerging picture of JA-Ile perception and signalling, COI1 operates as an E3 ubiquitin ligase that upon binding of JA-Ile targets JAZ repressors for degradation by the 26S proteasome, thereby derepressing transcription factors such as MYC2, which in turn activate JA-Ile-dependent transcriptional reprogramming. It is noteworthy that MYCs and different spliced variants of the JAZ proteins are involved in a negative regulatory feedback loop, which suggests a model that rapidly turns the transcriptional JA-Ile responses on and off and thereby avoids a detrimental overactivation of the pathway. This chapter highlights the most recent advances in our understanding of JA-Ile signalling, focusing on the latest repertoire of new targets of JAZ proteins to control different sets of JA-Ile-mediated responses, novel mechanisms of negative regulation of JA-Ile signalling, and hormonal cross-talk at the molecular level that ultimately determines plant adaptability and survival.

  11. Fine-tuning Food Safety Objectives and risk assessment.

    PubMed

    Havelaar, Arie H; Nauta, Maarten J; Jansen, Jaap T

    2004-05-15

    Food Safety Objectives (FSOs) have been proposed as a practical tool to translate public health targets for food safety into tolerable levels of pathogens in a food product. The FSO concept is subject to intensive debate, and has not been developed in detail. We evaluate the proposed definition of FSOs and their implementation from the perspective of Quantitative Microbiological Risk Assessment (QMRA). The relationship between QMRA and FSOs is illustrated by a model for the public health risk of Shiga-producing Escherichia coli in steak tartare. We conclude that the proposed definition of FSOs needs to be modified to properly account for variability in and uncertainty about the contamination of food with pathogenic microorganisms and emphasize that both prevalence and concentration of pathogens must be considered. For this purpose, we propose the P-D equivalence curve, a simple graphical tool to separate "tolerable" from "non-tolerable" combinations of prevalence and concentration (dose).

  12. Fine tuning GPS clock estimation in the MCS

    NASA Technical Reports Server (NTRS)

    Hutsell, Steven T.

    1995-01-01

    With the completion of a 24 operational satellite constellation, GPS is fast approaching the critical milestone, Full Operational Capability (FOC). Although GPS is well capable of providing the timing accuracy and stability figures required by system specifications, the GPS community will continue to strive for further improvements in performance. The GPS Master Control Station (MCS) recently demonstrated that timing improvements are always composite Clock, and hence, Kalman Filter state estimation, providing a small improvement to user accuracy.

  13. Fine-tuned shuttles for bone morphogenetic proteins.

    PubMed

    Wharton, Kristi A; Serpe, Mihaela

    2013-08-01

    Bone morphogenetic proteins (BMPs) are potent secreted signaling factors that trigger phosphorylation of Smad transcriptional regulators through receptor complex binding at the cell-surface. Resulting changes in target gene expression impact critical cellular responses during development and tissue homeostasis. BMP activity is tightly regulated in time and space by secreted modulators that control BMP extracellular distribution and availability for receptor binding. Such extracellular regulation is key for BMPs to function as morphogens and/or in the formation of morphogen activity gradients. Here, we review shuttling systems utilized to control the distribution of BMP ligands in tissue of various geometries, developing under different temporal constraints. We discuss the biological advantages for employing specific strategies for BMP shuttling and roles of varied ligand forms.

  14. Fine-Tuning the Wilson-Bappu Effect

    NASA Astrophysics Data System (ADS)

    Gomez, T.; Wallerstein, G.

    2011-12-01

    We have used the re-reduced Hipparcos parallaxes and extensive new observations from various sources to investigate the details of the Ca II emission line width vs. Mv relation first noted in Wilson & Vainu Bappu (1957). Only stars whose parallaxes exceed their probably error by at least a factor of 5 were used. The full range of Mv now extends from Mv =+14 to -5. Small but well defined deviations from a linear relationship are clearly present. The data have also been separately plotted for each luminosity class from V to Ib. Main sequence stars show significant curvature from Mv = 14 to 8. Stars of class III show a very nice linear curve. The supergiants, almost all of which are of class Ib, show the greatest scatter as originally noted by Wallerstein et al. (1999). For those stars the Wilson-Bappu Effect is not a useful method for deriving Mv. We discus the shape of the dispersion in log W0 at a given Mv and show that it is asymmetric. Individual measurements of logW0 are more likely to be above the mean rather than below it. This is probably due to intermittent activity that enhances the width of the Ca II emission line.

  15. Fine-Tuning ADAS Algorithm Parameters for Optimizing Traffic ...

    EPA Pesticide Factsheets

    With the development of the Connected Vehicle technology that facilitates wirelessly communication among vehicles and road-side infrastructure, the Advanced Driver Assistance Systems (ADAS) can be adopted as an effective tool for accelerating traffic safety and mobility optimization at various highway facilities. To this end, the traffic management centers identify the optimal ADAS algorithm parameter set that enables the maximum improvement of the traffic safety and mobility performance, and broadcast the optimal parameter set wirelessly to individual ADAS-equipped vehicles. After adopting the optimal parameter set, the ADAS-equipped drivers become active agents in the traffic stream that work collectively and consistently to prevent traffic conflicts, lower the intensity of traffic disturbances, and suppress the development of traffic oscillations into heavy traffic jams. Successful implementation of this objective requires the analysis capability of capturing the impact of the ADAS on driving behaviors, and measuring traffic safety and mobility performance under the influence of the ADAS. To address this challenge, this research proposes a synthetic methodology that incorporates the ADAS-affected driving behavior modeling and state-of-the-art microscopic traffic flow modeling into a virtually simulated environment. Building on such an environment, the optimal ADAS algorithm parameter set is identified through an optimization programming framework to enable th

  16. Researchers fine-tune production of energy crops

    SciTech Connect

    Parish, D.J. )

    1990-04-01

    Renewable energy sources, plant materials that can be processed into liquid fuels, are becoming increasingly important as fossil fuel sources dwindle and environmental impacts of releasing fossilized carbon into the atmosphere become more evident. But which plant species provide the most material and can be grown on land not used to produce food, feed, and fiber Switchgrass exceeds all other herbaceous species we have tested in production of biomass on marginal sites in the Virginia Piedmont reports David J. Parrish, Virginia Tech (Blacksburg, VA) professor of crop and soil environmental sciences. In a study sponsored by the U.S. Department of Energy (DOE) at Virginia Tech, graduate student Steven Nagle, Parrish, professor Dale Wolf, and associate professor W.L. Daniels are comparing the biomass productivity of switchgrass, weeping lovegrass, and tall fescue. Since 1985, the crops - selected for their marginal crop value - have been grown on 12 sites in the Virginia Piedmont. Planting was done using no-till procedures that slice but do not turn the soil, because the sites are subject to erosion. The two warm-season grasses are harvested once a year, the fescue twice. Switchgrass has been the most productive on clay soils, and lovegrass on sandy soil. In a second DOE-sponsored study - this one by graduate student Preston Sullivan, Parish, Wolf, Daniels, and Nagle - the Virginia Tech researchers have begun to investigate planting winter-annual legumes in with switchgrass as a source of nitrogen to reduce cost of production, and as a means to increase biomass. In the fall of 1988, crimson clover, arrowleaf clover, and hairy vetch were planted into the switchgrass stubble. Other plots of switchgrass are being provided with various levels of nitrogen fertilizer to compare those yields with legume-planted plots. Crimson clover had provided the most fall growth, but by mid-May 1989, the hairy vetch had produced a dense webbing of biomass over the new switchgrass.

  17. EARLY FLOWERING3 Redundancy Fine-Tunes Photoperiod Sensitivity.

    PubMed

    Rubenach, Andrew J S; Hecht, Valérie; Vander Schoor, Jacqueline K; Liew, Lim Chee; Aubert, Gregoire; Burstin, Judith; Weller, James L

    2017-04-01

    Three pea (Pisum sativum) loci controlling photoperiod sensitivity, HIGH RESPONSE (HR), DIE NEUTRALIS (DNE), and STERILE NODES (SN), have recently been shown to correspond to orthologs of Arabidopsis (Arabidopsis thaliana) circadian clock genes EARLY FLOWERING3 (ELF3), ELF4, and LUX ARRHYTHMO, respectively. A fourth pea locus, PHOTOPERIOD (PPD), also contributes to the photoperiod response in a similar manner to SN and DNE, and recessive ppd mutants on a spring-flowering hr mutant background show early, photoperiod-insensitive flowering. However, the molecular identity of PPD has so far remained elusive. Here, we show that the PPD locus also has a role in maintenance of diurnal and circadian gene expression rhythms and identify PPD as an ELF3 co-ortholog, termed ELF3b Genetic interactions between pea ELF3 genes suggest that loss of PPD function does not affect flowering time in the presence of functional HR, whereas PPD can compensate only partially for the lack of HR These results provide an illustration of how gene duplication and divergence can generate potential for the emergence of more subtle variations in phenotype that may be adaptively significant. © 2017 American Society of Plant Biologists. All Rights Reserved.

  18. Forecasting RVF Outbreaks-FineTuning a Model

    USDA-ARS?s Scientific Manuscript database

    An outbreak of Rift Valley Fever, causing severe illness in more than 600 people, resulting in more than 150 deaths, occurred in several locations in Kenya from November 2006 until early March 2007. The symposium (I and II) will review the epidemic and present findings from the multi-faceted invest...

  19. A "New" ERIC Thesaurus, Fine Tuned for Searching.

    ERIC Educational Resources Information Center

    Booth, Barbara

    1979-01-01

    Notes the history of the ERIC indexing vocabulary and the Identifier Cleanup undertaken to reduce scattering in the identifier field. Described in detail is the Vocabulary Improvement Project to review and revise the controlled vocabulary and produce a new Thesaurus of ERIC Descriptors. (CWM)

  20. Fine tuning of graphene properties by modification with aryl halogens.

    PubMed

    Bouša, D; Pumera, M; Sedmidubský, D; Šturala, J; Luxa, J; Mazánek, V; Sofer, Z

    2016-01-21

    Graphene and its derivatives belong to one of the most intensively studied materials. The radical reaction using halogen derivatives of arene-diazonium salts can be used for effective control of graphene's electronic properties. In our work we investigated the influence of halogen atoms (fluorine, chlorine, bromine and iodine) as well as their position on the benzene ring towards the electronic and electrochemical properties of modified graphenes. The electronegativity as well as the position of the halogen atoms on the benzene ring has crucial influence on graphene's properties due to the inductive and mesomeric effects. The results of resistivity measurement are in good agreement with the theoretical calculations of electron density within chemically modified graphene sheets. Such simple chemical modifications of graphene can be used for controllable and scalable synthesis of graphene with tunable transport properties.

  1. Carbohydrate-binding modules: fine-tuning polysaccharide recognition

    PubMed Central

    2004-01-01

    The enzymic degradation of insoluble polysaccharides is one of the most important reactions on earth. Despite this, glycoside hydrolases attack such polysaccharides relatively inefficiently as their target glycosidic bonds are often inaccessible to the active site of the appropriate enzymes. In order to overcome these problems, many of the glycoside hydrolases that utilize insoluble substrates are modular, comprising catalytic modules appended to one or more non-catalytic CBMs (carbohydrate-binding modules). CBMs promote the association of the enzyme with the substrate. In view of the central role that CBMs play in the enzymic hydrolysis of plant structural and storage polysaccharides, the ligand specificity displayed by these protein modules and the mechanism by which they recognize their target carbohydrates have received considerable attention since their discovery almost 20 years ago. In the last few years, CBM research has harnessed structural, functional and bioinformatic approaches to elucidate the molecular determinants that drive CBM–carbohydrate recognition. The present review summarizes the impact structural biology has had on our understanding of the mechanisms by which CBMs bind to their target ligands. PMID:15214846

  2. A Presynaptic Gain Control Mechanism Fine-Tunes Olfactory Behavior

    PubMed Central

    Root, Cory M.; Masuyama, Kaoru; Green, David S.; Enell, Lina E.; Nässel, Dick R.; Lee, Chi-Hon; Wang, Jing W.

    2008-01-01

    Early sensory processing can play a critical role in sensing environmental cues. We have investigated the physiological and behavioral function of gain control at the first synapse of olfactory processing in Drosophila. We report that olfactory receptor neurons (ORNs) express the GABAB receptor (GABABR) and its expression expands the dynamic range of ORN synaptic transmission that is preserved in projection neuron responses. Strikingly, we find that different ORN channels have unique baseline levels of GABABR expression. ORNs that sense the aversive odorant CO2 do not express GABABRs nor exhibit any presynaptic inhibition. In contrast, pheromone-sensing ORNs express a high level of GABABRs and exhibit strong presynaptic inhibition. Furthermore, a behavioral significance of presynaptic inhibition was revealed by a courtship behavior in which pheromone-dependent mate localization is impaired in flies that lack GABABRs in specific ORNs. Together, these findings indicate that different olfactory receptor channels may employ heterogeneous presynaptic gain control as a mechanism to allow an animal’s innate behavioral responses to match its ecological needs. PMID:18667158

  3. Fine-Tuning ADAS Algorithm Parameters for Optimizing Traffic ...

    EPA Pesticide Factsheets

    With the development of the Connected Vehicle technology that facilitates wirelessly communication among vehicles and road-side infrastructure, the Advanced Driver Assistance Systems (ADAS) can be adopted as an effective tool for accelerating traffic safety and mobility optimization at various highway facilities. To this end, the traffic management centers identify the optimal ADAS algorithm parameter set that enables the maximum improvement of the traffic safety and mobility performance, and broadcast the optimal parameter set wirelessly to individual ADAS-equipped vehicles. After adopting the optimal parameter set, the ADAS-equipped drivers become active agents in the traffic stream that work collectively and consistently to prevent traffic conflicts, lower the intensity of traffic disturbances, and suppress the development of traffic oscillations into heavy traffic jams. Successful implementation of this objective requires the analysis capability of capturing the impact of the ADAS on driving behaviors, and measuring traffic safety and mobility performance under the influence of the ADAS. To address this challenge, this research proposes a synthetic methodology that incorporates the ADAS-affected driving behavior modeling and state-of-the-art microscopic traffic flow modeling into a virtually simulated environment. Building on such an environment, the optimal ADAS algorithm parameter set is identified through an optimization programming framework to enable th

  4. Fine-Tuning Development Through Antagonistic Peptides: An Emerging Theme.

    PubMed

    Lee, Jin Suk; De Smet, Ive

    2016-12-01

    Peptide ligand-receptor kinase interactions have emerged as a key component of plant growth and development. Now, highly related small signaling peptides have been shown to act antagonistically on the same receptor kinase, providing new insights into how plants optimize developmental processes using competitive peptides.

  5. ESP Needs Washback and the Fine Tuning of Driving Instruction

    ERIC Educational Resources Information Center

    Freiermuth, Mark R.

    2007-01-01

    Workplace needs are often difficult for English for Specific Purposes (ESP) teachers to assess due to a variety of obstacles that can restrict opportunities to analyze the existing needs. Nevertheless, the workers' needs may be recognized by employing techniques aimed at extracting information from the workers themselves. Japanese university…

  6. Diffractive digital lensless holographic microscopy with fine spectral tuning.

    PubMed

    Mendoza-Yero, Omel; Tajahuerce, Enrique; Lancis, Jesús; Garcia-Sucerquia, Jorge

    2013-06-15

    We experimentally demonstrate an all-diffractive optical setup for digital lensless holographic microscopy with easy wavelength line selection and micrometric resolution. In the proposed system, an ultrashort laser pulse is focused with a diffractive lens (DL) onto a pinhole of diameter close to its central wavelength to achieve a highly spatially coherent illumination cone as well as a spectral line with narrow width. To scan the complete spectrum of the light source the DL is displaced with respect to the pinhole plane. The proposed microscopy setup allows us to spectrally separate contributions from different sections of a sample, which may be attractive for several applications in life sciences.

  7. Fine tuning of graphene properties by modification with aryl halogens

    NASA Astrophysics Data System (ADS)

    Bouša, D.; Pumera, M.; Sedmidubský, D.; Šturala, J.; Luxa, J.; Mazánek, V.; Sofer, Z.

    2016-01-01

    Graphene and its derivatives belong to one of the most intensively studied materials. The radical reaction using halogen derivatives of arene-diazonium salts can be used for effective control of graphene's electronic properties. In our work we investigated the influence of halogen atoms (fluorine, chlorine, bromine and iodine) as well as their position on the benzene ring towards the electronic and electrochemical properties of modified graphenes. The electronegativity as well as the position of the halogen atoms on the benzene ring has crucial influence on graphene's properties due to the inductive and mesomeric effects. The results of resistivity measurement are in good agreement with the theoretical calculations of electron density within chemically modified graphene sheets. Such simple chemical modifications of graphene can be used for controllable and scalable synthesis of graphene with tunable transport properties.Graphene and its derivatives belong to one of the most intensively studied materials. The radical reaction using halogen derivatives of arene-diazonium salts can be used for effective control of graphene's electronic properties. In our work we investigated the influence of halogen atoms (fluorine, chlorine, bromine and iodine) as well as their position on the benzene ring towards the electronic and electrochemical properties of modified graphenes. The electronegativity as well as the position of the halogen atoms on the benzene ring has crucial influence on graphene's properties due to the inductive and mesomeric effects. The results of resistivity measurement are in good agreement with the theoretical calculations of electron density within chemically modified graphene sheets. Such simple chemical modifications of graphene can be used for controllable and scalable synthesis of graphene with tunable transport properties. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr06295k

  8. Is Fine-Tuning Possible with Grade-Focused Students?

    ERIC Educational Resources Information Center

    Frost, Gail; Connolly, Maureen

    2016-01-01

    In our service-learning courses, students work with real people and record and reflect on these experiences, to learn appropriate professional behavior, how to think creatively, and how to respond to changing circumstances. Many of our students are strategic learners, characterized by alertness to assessment and intention to achieve the highest…

  9. Fine-Tuning the Craft of Teaching by Discussion

    ERIC Educational Resources Information Center

    Huang, Li-Shih

    2005-01-01

    Extensive research in cognitive psychology and education shows that discussion facilitates "depth of processing" (Craik & Lockhart, 1972), which in turn promotes thinking, understanding, and retaining information. It is also well recognized that an effectively facilitated discussion is one of the most valuable vehicles for learning. In MBA…

  10. Fine-Tuning the Craft of Teaching by Discussion

    ERIC Educational Resources Information Center

    Huang, Li-Shih

    2005-01-01

    Extensive research in cognitive psychology and education shows that discussion facilitates "depth of processing" (Craik & Lockhart, 1972), which in turn promotes thinking, understanding, and retaining information. It is also well recognized that an effectively facilitated discussion is one of the most valuable vehicles for learning. In MBA…

  11. Improving fine-tuning in composite Higgs models

    NASA Astrophysics Data System (ADS)

    Banerjee, Avik; Bhattacharyya, Gautam; Ray, Tirtha Sankar

    2017-08-01

    In this paper we investigate the next-to-minimal composite Higgs model with a SO (6 ) /SO (5 ) coset, whose pseudo-Nambu-Goldstone boson sector includes a Standard Model singlet in addition to the usual Higgs doublet. The fermions are embedded in the representation 6 of SO(6). We study the region of parameter space of the model where the radiatively generated potential has global minima with both the doublet and the singlet fields developing vacuum expectation values. We investigate the consequences of kinetic and mass mixing between the Higgs and the singlet scalar that arise in this framework. We demonstrate that the ensuing doublet-singlet mixing can provide a handle to accommodate heavier resonances (top partners) for a given compositeness scale as compared to the minimal composite Higgs model, thus relaxing the tension with the direct LHC bounds. The main phenomenological consequence of this is a sizable deviation of the Higgs couplings from the Standard Model predictions. While the present experimental precision in the measurement of the Higgs couplings still allows for considerable release of this tension, future measurements of the Higgs branching ratios with increased precision would lead to stringent constraints on this setup.

  12. Fine-tunable plasma nano-machining for fabrication of 3D hollow nanostructures: SERS application.

    PubMed

    Mehrvar, L; Hajihoseini, H; Mahmoodi, H; Tavassoli, S H; Fathipour, M; Mohseni, S M

    2017-08-04

    Novel processing sequences for the fabrication of artificial nanostructures are in high demand for various applications. In this paper, we report on a fine-tunable nano-machining technique for the fabrication of 3D hollow nanostructures. This technique originates from redeposition effects occurring during Ar dry etching of nano-patterns. Different geometries of honeycomb, double ring, nanotube, cone and crescent arrays have been successfully fabricated from various metals such as Au, Ag, Pt and Ti. The geometrical parameters of the 3D hollow nanostructures can be straightforwardly controlled by tuning the discharge plasma pressure and power. The structure and morphology of nanostructures are probed using atomic force microscopy (AFM), scanning electron microscopy (SEM), optical emission spectroscopy (OES) and energy dispersive x-ray spectroscopy (EDS). Finally, a Ag nanotube array was assayed for application in surface enhanced Raman spectroscopy (SERS), resulting in an enhancement factor (EF) of 5.5 × 10(5), as an experimental validity proof consistent with the presented simulation framework. Furthermore, it was found that the theoretical EF value for the honeycomb array is in the order of 10(7), a hundred times greater than that found in nanotube array.

  13. Fine-tunable plasma nano-machining for fabrication of 3D hollow nanostructures: SERS application

    NASA Astrophysics Data System (ADS)

    Mehrvar, L.; Hajihoseini, H.; Mahmoodi, H.; Tavassoli, S. H.; Fathipour, M.; Mohseni, S. M.

    2017-08-01

    Novel processing sequences for the fabrication of artificial nanostructures are in high demand for various applications. In this paper, we report on a fine-tunable nano-machining technique for the fabrication of 3D hollow nanostructures. This technique originates from redeposition effects occurring during Ar dry etching of nano-patterns. Different geometries of honeycomb, double ring, nanotube, cone and crescent arrays have been successfully fabricated from various metals such as Au, Ag, Pt and Ti. The geometrical parameters of the 3D hollow nanostructures can be straightforwardly controlled by tuning the discharge plasma pressure and power. The structure and morphology of nanostructures are probed using atomic force microscopy (AFM), scanning electron microscopy (SEM), optical emission spectroscopy (OES) and energy dispersive x-ray spectroscopy (EDS). Finally, a Ag nanotube array was assayed for application in surface enhanced Raman spectroscopy (SERS), resulting in an enhancement factor (EF) of 5.5 × 105, as an experimental validity proof consistent with the presented simulation framework. Furthermore, it was found that the theoretical EF value for the honeycomb array is in the order of 107, a hundred times greater than that found in nanotube array.

  14. Model-independent particle accelerator tuning

    DOE PAGES

    Scheinker, Alexander; Pang, Xiaoying; Rybarcyk, Larry

    2013-10-21

    We present a new model-independent dynamic feedback technique, rotation rate tuning, for automatically and simultaneously tuning coupled components of uncertain, complex systems. The main advantages of the method are: 1) It has the ability to handle unknown, time-varying systems, 2) It gives known bounds on parameter update rates, 3) We give an analytic proof of its convergence and its stability, and 4) It has a simple digital implementation through a control system such as the Experimental Physics and Industrial Control System (EPICS). Because this technique is model independent it may be useful as a real-time, in-hardware, feedback-based optimization scheme formore » uncertain and time-varying systems. In particular, it is robust enough to handle uncertainty due to coupling, thermal cycling, misalignments, and manufacturing imperfections. As a result, it may be used as a fine-tuning supplement for existing accelerator tuning/control schemes. We present multi-particle simulation results demonstrating the scheme’s ability to simultaneously adaptively adjust the set points of twenty two quadrupole magnets and two RF buncher cavities in the Los Alamos Neutron Science Center Linear Accelerator’s transport region, while the beam properties and RF phase shift are continuously varying. The tuning is based only on beam current readings, without knowledge of particle dynamics. We also present an outline of how to implement this general scheme in software for optimization, and in hardware for feedback-based control/tuning, for a wide range of systems.« less

  15. Three-dimensional cavity nanoantennas with resonant-enhanced surface plasmons as dynamic color-tuning reflectors.

    PubMed

    Fan, J R; Wu, W G; Chen, Z J; Zhu, J; Li, J

    2017-03-09

    As plasmonic antennas for surface-plasmon-assisted control of optical fields at specific frequencies, metallic nanostructures have recently emerged as crucial optical components for fascinating plasmonic color engineering. Particularly, plasmonic resonant nanocavities can concentrate lightwave energy to strongly enhance light-matter interactions, making them ideal candidates as optical elements for fine-tuning color displays. Inspired by the color mixing effect found on butterfly wings, a new type of plasmonic, multiresonant, narrow-band (the minimum is about 45 nm), high-reflectance (the maximum is about 95%), and dynamic color-tuning reflector is developed. This is achieved from periodic patterns of plasmonic resonant nanocavities in free-standing capped-pillar nanostructure arrays. Such cavity-coupling structures exhibit multiple narrow-band selective and continuously tunable reflections via plasmon standing-wave resonances. Consequently, they can produce a variety of dark-field vibrant reflective colors with good quality, strong color signal and fine tonal variation at the optical diffraction limit. This proposed multicolor scheme provides an elegant strategy for realizing personalized and customized applications in ultracompact photonic data storage and steganography, colorimetric sensing, 3D holograms and other plasmon-assisted photonic devices.

  16. Reviews Book: At Home: A Short History of Private Life Book: The Story of Mathematics Book: Time Travel: A Writer's Guide to the Real Science of Plausible Time Travel Equipment: Rotational Inertial Wands DVD: Planets Book: The Fallacy of Fine-Tuning Equipment: Scale with Dial Equipment: Infrared Thermometers Book: 300 Science and History Projects Book: The Nature of Light and Colour in the Open Air Equipment: Red Tide Spectrometer Web Watch

    NASA Astrophysics Data System (ADS)

    2011-09-01

    WE RECOMMEND The Story of Mathematics Book shows the link between maths and physics Time Travel: A Writer's Guide to the Real Science of Plausible Time Travel Book explains how to write good time-travelling science fiction Rotational Inertial Wands Wands can help explore the theory of inertia Infrared Thermometers Kit measures temperature differences Red Tide Spectrometer Spectrometer gives colour spectra WORTH A LOOK At Home: A Short History of Private Life Bryson explores the history of home life The Fallacy of Fine-Tuning Book wades into the science/religion debate Scale with Dial Cheap scales can be turned into Newton measuring scales 300 Science History Projects Fun science projects for kids to enjoy The Nature of Light and Colour in the Open Air Text looks at fascinating optical effects HANDLE WITH CARE Planets DVD takes a trip through the solar system WEB WATCH Websites offer representations of nuclear chain reactions

  17. Magnetic tuning of electrically resonant metamaterial with inclusion of ferrite

    NASA Astrophysics Data System (ADS)

    Kang, Lei; Zhao, Qian; Zhao, Hongjie; Zhou, Ji

    2008-10-01

    We experimentally demonstrate a magnetic tuning of electrically resonant metamaterial (EMM) at microwave frequencies by introducing microwave ferrite rods into the periodic array of electrically resonant element. Different from those based on controlling the capacitance of equivalent LC circuit, this tunability arises from a mechanism of magnetically tuning the inductance of resonant element via the active ambient effective permeability. For magnetic fields from 0 to 5000 Oe, resonance frequency of the EMM can be continuously and reversibly tuned in a range of about 800 MHz. The active effective permittivity has also been investigated through the simulated scattering parameters.

  18. Spatially selective optical tuning of quantum dot thin film luminescence.

    PubMed

    Chen, Jixin; Chan, Yang-Hsiang; Yang, Tinglu; Wark, Stacey E; Son, Dong Hee; Batteas, James D

    2009-12-30

    Photolithographically generated patterns have been created on immobilized CdSe QD thin films by fine-tuning their optical properties (intensity and emission wavelength) postsynthetically. These optically modified QDs show enhanced selectivity for binding of different ligands, affording the ability to fabricate optically reconfigurable surfaces for display or sensing applications. The patterns may be readily generated with any typical optical lithographic approach.

  19. Dancing to a Different Tune: Adaptive Evolution Fine-Tunes Protein Dynamics

    DTIC Science & Technology

    2015-09-01

    techniques………………………………………… 238 8.1.1 Sterilisation technique………………………………………… 238 8.1.2 Bacterial strains and plasmids………………………………… 238 8.1.3 Media...preparation…………………………………………….. 239 8.1.4 Antibiotics……………………………………………………. 239 8.1.5 Inoculation of bacterial culture………………………………… 239 8.1.6...human) interventions against them.8 For instance, therapeutic agents, such as antibiotics, are introduced as a treatment for bacterial infections

  20. Tuned Chamber Core Panel Acoustic Test Results

    NASA Technical Reports Server (NTRS)

    Schiller, Noah H.; Allen, Albert R.

    2016-01-01

    This report documents acoustic testing of tuned chamber core panels, which can be used to supplement the low-frequency performance of conventional acoustic treatment. The tuned chamber core concept incorporates low-frequency noise control directly within the primary structure and is applicable to sandwich constructions with a directional core, including corrugated-, truss-, and fluted-core designs. These types of sandwich structures have long, hollow channels (or chambers) in the core. By adding small holes through one of the facesheets, the hollow chambers can be utilized as an array of low-frequency acoustic resonators. These resonators can then be used to attenuate low-frequency noise (below 400 Hz) inside a vehicle compartment without increasing the weight or size of the structure. The results of this test program demonstrate that the tuned chamber core concept is effective when used in isolation or combined with acoustic foam treatments. Specifically, an array of acoustic resonators integrated within the core of the panels was shown to improve both the low-frequency absorption and transmission loss of the structure in targeted one-third octave bands.

  1. Complier-Directed Automatic Performance Tuning (TUNE) Final Report

    SciTech Connect

    Chame, Jacqueline

    2013-06-07

    TUNE was created to develop compiler-directed performance tuning technology targeting the Cray XT4 system at Oak Ridge. TUNE combines compiler technology for model-guided empirical optimization for memory hierarchies with SIMD code generation. The goal of this performance-tuning technology is to yield hand-tuned levels of performance on DOE Office of Science computational kernels, while allowing application programmers to specify their computations at a high level without requiring manual optimization. Overall, TUNE aims to make compiler technology for SIMD code generation and memory hierarchy optimization a crucial component of high-productivity Petaflops computing through a close collaboration with the scientists in national laboratories.

  2. Left-handed extraordinary optical transmission through a photonic crystal of subwavelength hole arrays.

    PubMed

    Beruete, Miguel; Sorolla, Mario; Campillo, Igor

    2006-06-12

    Metamaterial structures are artificial materials that show unconventional electromagnetic properties such as photonic band-gap, extraordinary optical transmission and left-handed propagation. Up to now, relations of photonic crystals and negative refraction have been shown as well as of photonic crystals and sub-wavelength hole arrays. Here we report a left-handed metamaterial engineered by a combination of sub-wavelength hole array plates periodically stacked to form a photonic crystal structure. It is shown the possibility of fine-tuning the metamaterial in order to permit extraordinary optical transmission and left-handed behaviour. Our work demonstrates the feasibility of engineering left-handed metamaterials by just drilling holes in metallic plates and brings together single structure photonic crystals, extraordinary optical transmission and left-handed behaviour.

  3. Tuning the Blend

    ERIC Educational Resources Information Center

    Schaffhauser, Dian

    2012-01-01

    "Tuning the blend" is a phrase that educators hear a lot these days. It refers to finding the correct balance of online activities and face-to-face instruction in hybrid--or blended--courses. Finding a mix that meets the needs of both faculty and students requires experimentation, experience, and constant tweaking. And, as with coffee, the same…

  4. Electronically Tuned Microwave Oscillator

    NASA Technical Reports Server (NTRS)

    Lakshminarayana, Mysore

    1987-01-01

    Features include low phase noise and frequency stability. Bias-tuned, low-phase-noise microwave oscillator circuit based on npn bipolar transistor and dielectric resonator. Operating at frequency of about 8.4 GHz, oscillator adjusted to give low phase noise, relatively flat power output versus frequency, and nearly linear frequency versus bias voltage.

  5. Tuning the Blend

    ERIC Educational Resources Information Center

    Schaffhauser, Dian

    2012-01-01

    "Tuning the blend" is a phrase that educators hear a lot these days. It refers to finding the correct balance of online activities and face-to-face instruction in hybrid--or blended--courses. Finding a mix that meets the needs of both faculty and students requires experimentation, experience, and constant tweaking. And, as with coffee, the same…

  6. Tuning toward Completion

    ERIC Educational Resources Information Center

    Kolb, Marcus; Kalina, Michelle; Chapman, Adina

    2013-01-01

    The Obama administration and the Lumina Foundation have been the principal drivers focusing the nation on increasing the number of high-quality degrees and credentials. Tuning, a faculty-driven process for defining clear student learning outcomes--what a student should know, understand, and be able to do--is one of the ways to support this goal.

  7. New design concepts for ferrite-tuned low-energy-booster cavities

    SciTech Connect

    Schaffer, G.

    1991-05-01

    The design concepts for ferrite-tuned accelerating cavities discussed in this paper differ from conventional solutions using thick ferrite toroids for frequency tuning. Instead, tuners consisting of an array of ferrite-loaded striplines are investigated. These promise more efficient cooling and higher operational reliability. Layout examples for the SSC-LEB rf system are presented (tuning range 47.5 to 59.8 MHz, repetition frequency 10 Hz). 15 refs., 4 figs., 1 tab.

  8. RF tuning element

    NASA Technical Reports Server (NTRS)

    McGrath, William R. (Inventor); Lubecke, Victor M. (Inventor)

    1992-01-01

    A device for tuning a circuit includes a substrate, a transmission line on the substrate that includes first and second conductors coupled to a circuit to be tuned, and a movable short-circuit for varying the impedance the transmission line presents to the circuit to be tuned. The movable short-circuit includes a dielectric layer disposed atop the transmission line and a distributed shorting element in the form of a conductive member that is configured to be slid along at least a portion of the transmission line atop the dielectric layer. The conductive member is configured to span the first and second conductors of the transmission line and to define at least a first opening that spans the two conductors so that the conductive member includes first and second sections separated by the first opening. The first and second sections of the conductive member combine with the first and second conductors of the transmission line to form first and second low impedance sections of transmission line, and the opening combines with the first and second conductors of the transmission line and the dielectric layer to form a first high impedance section of transmission line intermediate the first and second low impedance sections. Each of the first low impedance section and the first high impedance section have a length along the transmission line of approximately one-quarter wavelength, thus providing a periodic variation of transmission line impedance. That enhances reflection of rf power.

  9. Magnetic arrays

    DOEpatents

    Trumper, D.L.; Kim, W.; Williams, M.E.

    1997-05-20

    Electromagnet arrays are disclosed which can provide selected field patterns in either two or three dimensions, and in particular, which can provide single-sided field patterns in two or three dimensions. These features are achieved by providing arrays which have current densities that vary in the windings both parallel to the array and in the direction of array thickness. 12 figs.

  10. Magnetic arrays

    SciTech Connect

    Trumper, David L.; Kim, Won-jong; Williams, Mark E.

    1997-05-20

    Electromagnet arrays which can provide selected field patterns in either two or three dimensions, and in particular, which can provide single-sided field patterns in two or three dimensions. These features are achieved by providing arrays which have current densities that vary in the windings both parallel to the array and in the direction of array thickness.

  11. A Ka-Band (26 GHz) Circularly Polarized 2x2 Microstrip Patch Sub-Array with Compact Feed

    NASA Technical Reports Server (NTRS)

    Chrysler, Andrew; Furse, Cynthia; Simons, Rainee N.; Miranda, Felix A.

    2017-01-01

    A Ka-Band (26 gigahertz) 2 by 2 sub-array with square-shaped microstrip patch antenna elements having two truncated corners for circular polarization (CP) is presented. In addition, the layout for a new compact microstrip feed network for the sub-array is also presented. The compact feed network offers a footprint size reduction of near 60 percent over traditional sub-array at 26 gigahertz. Experimental data indicates that a truncation amount a equals 0.741 millimeters for an isolated patch element results in a return loss (S (sub II)) of minus 35 decibels at 26.3 gigahertz. Furthermore, the measured S (sub II) for the proof-of-concept sub-array with the above elements is better than minus 10.0 decibels at 27.7 gigahertz. However, the impedance match and the operating frequency can be fine-tuned to 26 gigahertz by adjusting the feed network dimensions. Lastly, good agreement is observed between the measured and simulated S (sub II) for the subarray for both right hand and left hand CP. The goal of this effort is utilize the above sub-array as a building block for a larger N by N element array, which would serve as a feed for a reflector antenna for satellite communications.

  12. Fine Arts Evaluation.

    ERIC Educational Resources Information Center

    Nanaimo School District #68 (British Columbia).

    The fine arts as defined by the Ministry of Education (British Columbia) include music, art, and drama with the curriculum focusing on two concepts: creation and appreciation. One of the aims of School District #68 (Nanaimo) is to provide students with the opportunity to gain exposure to, and experience in, fine arts. The Fine Arts Evaluation…

  13. Electronically tuned optical filters

    NASA Technical Reports Server (NTRS)

    Castellano, J. A.; Pasierb, E. F.; Oh, C. S.; Mccaffrey, M. T.

    1972-01-01

    A detailed account is given of efforts to develop a three layer, polychromic filter that can be tuned electronically. The operation of the filter is based on the cooperative alignment of pleochroic dye molecules by nematic liquid crystals activated by electric fields. This orientation produces changes in the optical density of the material and thus changes in the color of light transmitted through the medium. In addition, attempts to improve materials and devices which employ field induced changes of a cholesteric to a nematic liquid crystal are presented.

  14. A Cyber Expert System for Auto-Tuning Powered Prosthesis Impedance Control Parameters.

    PubMed

    Huang, He; Crouch, Dustin L; Liu, Ming; Sawicki, Gregory S; Wang, Ding

    2016-05-01

    Typically impedance control parameters (e.g., stiffness and damping) in powered lower limb prostheses are fine-tuned by human experts (HMEs), which is time and resource intensive. Automated tuning procedures would make powered prostheses more practical for clinical use. In this study, we developed a novel cyber expert system (CES) that encoded HME tuning decisions as computer rules to auto-tune control parameters for a powered knee (passive ankle) prosthesis. The tuning performance of CES was preliminarily quantified on two able-bodied subjects and two transfemoral amputees. After CES and HME tuning, we observed normative prosthetic knee kinematics and improved or slightly improved gait symmetry and step width within each subject. Compared to HME, the CES tuning procedure required less time and no human intervention. Hence, using CES for auto-tuning prosthesis control was a sound concept, promising to enhance the practical value of powered prosthetic legs. However, the tuning goals of CES might not fully capture those of the HME. This was because we observed that HME tuning reduced trunk sway, while CES sometimes led to slightly increased trunk motion. Additional research is still needed to identify more appropriate tuning objectives for powered prosthetic legs to improve amputees' walking function.

  15. Grating tuned unstable resonator laser cavity

    DOEpatents

    Johnson, Larry C.

    1982-01-01

    An unstable resonator to be used in high power, narrow line CO.sub.2 pump lasers comprises an array of four reflectors in a ring configuration wherein spherical and planar wavefronts are separated from each other along separate optical paths and only the planar wavefronts are impinged on a plane grating for line tuning. The reflector array comprises a concave mirror for reflecting incident spherical waves as plane waves along an output axis to form an output beam. A plane grating on the output axis is oriented to reflect a portion of the output beam off axis onto a planar relay mirror spaced apart from the output axis in proximity to the concave mirror. The relay mirror reflects plane waves from the grating to impinge on a convex expanding mirror spaced apart from the output axis in proximity to the grating. The expanding mirror reflects the incident planar waves as spherical waves to illuminate the concave mirror. Tuning is provided by rotating the plane grating about an axis normal to the output axis.

  16. On the sensing and tuning of progressive structural vibration waves.

    PubMed

    Minikes, Adi; Gabay, Ran; Bucher, Izhak; Feldman, Michael

    2005-09-01

    Progressive flexural waves can be generated only in finite structures by fine tuning the excitation and the boundary conditions. The tuning process eliminates the reflected waves arising from discontinuities and edge effects. This work presents and expands two new methods for the identification and tuning of traveling waves. One is a parametric method based on fitting an ellipse to the complex spatial amplitude distribution. The other is a nonparametric method based on the Hilbert transform providing a space-localized estimate. With these methods, an optimization-based tuning of transverse flexural waves in a one-dimensional structure, a vibrating beam, is developed. Existing methods are designed for a single frequency and are based on either combining two vibration modes or mechanical impedance matching. Such methods are limited to a designated excitation frequency determined by a specific configuration of the system. With the proposed methods, structural progressive waves can be generated for a wide range of frequencies under the same given system configuration and can be tuned in real time to accommodate changes in boundary conditions. An analytical study on the nature of the optimal excitation conditions has been carried out, revealing singular configurations. The experimental verification of the sensing and tuning methods is demonstrated on a dedicated laboratory prototype. The proposed methods are not confined to mechanical waves and present a comprehensive approach applicable for other physical wave phenomena.

  17. Generation of steep phase anisotropy with zero-backscattering by arrays of coupled dielectric nano-resonators

    SciTech Connect

    Wang, Feng; Wei, Qi-Huo; Htoon, Han

    2014-09-22

    The interaction of light with high-permittivity dielectric nano-resonators can lead to zero-backscattering (i.e., full transmission), attributed to the simultaneous excitation of electric and magnetic dipolar modes in these resonators. In this paper, we numerically demonstrate that 2-dimensional Si nanocuboid arrays with anisotropic periodicity and finely tuned cuboid height can generate up to 2π optical phase anisotropy with zero-backscattering. Especially, by introducing strong Fano-type coupling into unit cells of the array, the induced phase anisotropy becomes ultra-steep with excitation wavelength. These special optical properties promise applications in various transmissive photonic devices, and we discuss their potential applications in transmissive polarization conversion and sensing.

  18. Dynamical Tuning of the Initial Condition in Small Field Inflations - Can We Testify the CW Mechanism in the Universe

    NASA Astrophysics Data System (ADS)

    Iso, Satoshi

    I explain the cosmological consequence of the particle physics models with the Coleman-Weinberg (CW) type potential. Such particle physics models generally predict the small field inflation (SFI), but the SFI requires a very unnatural fine-tuning of the initial condi- tion. In this talk, I reviewed our proposal1 to solve the fine-tuning problem dynamically by a trapping of the inflaton field due to the preheating before the SFI starts.

  19. Tuning Broadband Microwave Amplifiers

    SciTech Connect

    Alaniz, Gabriel

    2003-09-05

    The PEP-II/DA {Phi} NE/ALS longitudinal feedback systems are complex wide bandwidth systems requiring analog, digital and microwave circuits. The solid-state amplifier is one of the components in the microwave circuit that is required to suppress the coupled bunch instabilities that exist in the PEP-II accelerator. The suppression is achieved by using an antenna as a kicker structure that provides an electric field in order to increase or decrease the energy of particles passing through the structure. The amplifier is made up of sixteen 30 to 35W microstrip GaAs FET modules that are combined to obtain 500W over a bandwidth of 850MHz to 1850MHz. The amplifier malfunctioned causing a reduction in the functionality and power output of the individual GaAs FET modules. The amplifier must be repaired. After repair, the amplifier must be tuned to optimize the gain while maintaining proper power output. The amplifier is tuned using microstrip circuit techniques. A variety of microstrip methods are used to obtain the proper line impedance. The result is a working amplifier that operates efficiently.

  20. Reversible hysteresis loop tuning

    NASA Astrophysics Data System (ADS)

    Berger, A.; Binek, Ch.; Margulies, D. T.; Moser, A.; Fullerton, E. E.

    2006-02-01

    We utilize antiferromagnetically coupled bilayer structures to magnetically tune hysteresis loop properties. Key element of this approach is the non-overlapping switching field distribution of the two magnetic layers that make up the system: a hard magnetic CoPtCrB layer (HL) and a soft magnetic CoCr layer (SL). Both layers are coupled antiferromagnetically through an only 0.6-nm-thick Ru interlayer. The non-overlapping switching field distribution allows the measurement of magnetization reversal in the SL at low fields while keeping the magnetization state of the HL unperturbed. Applying an appropriate high field or high field sequence changes the magnetic state of the HL, which then influences the SL magnetization reversal due to the interlayer coupling. In this way, the position and shape of the SL hysteresis loop can be changed or tuned in a fully reversible and highly effective manner. Here, we study specifically how the SL hysteresis loop characteristics change as we move the HL through an entire high field hysteresis loop sequence.

  1. ORMOSIL thin films: tuning mechanical properties via a nanochemistry approach.

    PubMed

    Palmisano, Giovanni; Le Bourhis, Eric; Ciriminna, Rosaria; Tranchida, Davide; Pagliaro, Mario

    2006-12-19

    The mechanical properties (hardness and elastic modulus) of organically modified silicate thin films can be finely tuned by varying the degree of alkylation and thus the fraction of six- and four-membered siloxane rings in the organosilica matrix. This opens the way to large tunability of parameters that are of crucial practical importance for films that are finding increasing application in numerous fields ranging from microelectronics to chemical sensing.

  2. Multimodal tuned dynamic absorber for split Stirling linear cryocooler

    NASA Astrophysics Data System (ADS)

    Veprik, A.; Tuito, A.

    2017-02-01

    Forthcoming low size, weight, power and price split Stirling linear cryocoolers may rely on electro-dynamically driven single-piston compressors and pneumatically driven expanders interconnected by the configurable transfer line. For compactness, compressor and expander units may be placed in a side-by-side manner, thus producing tonal vibration export comprising force and moment components. In vibration sensitive applications, this may result in excessive angular line of sight jitter and translational defocusing affecting the image quality. The authors present Multimodal Tuned Dynamic Absorber (MTDA), having one translational and two tilting modes essentially tuned to the driving frequency. The dynamic reactions (force and moment) produced by such a MTDA are simultaneously counterbalancing force and moment vibration export produced by the cryocooler. The authors reveal the design details, the method of fine modal tuning and outcomes of numerical simulation on attainable performance.

  3. Multimodal tuned dynamic absorber for split Stirling linear cryocooler

    NASA Astrophysics Data System (ADS)

    Veprik, Alexander; Tuito, Avi

    2016-05-01

    Low size, weight, power and price split Stirling linear cryocooler usually comprises electro-dynamically driven compressor and pneumatically driven expander which are side-by-side fixedly mounted upon the common frame and interconnected by the configurable transfer line. Vibration export produced by such a cryocooler comprises of a pair of tonal forces, the frequency of which essentially equals fixed driving frequency. In vibration sensitive applications, this may result in excessive angular line of sight jitter and translational defocusing affecting the image quality. The authors present Multimodal Tuned Dynamic Absorber, having one translational and two tilting modes essentially tuned to the driving frequency. Dynamic analysis shows that the dynamic reactions (force and moment) produced by such a dynamic absorber are capable of simultaneous attenuation of translational and tilting components of cryocooler induced vibration. The authors reveal the preferable design, the method of fine tuning and outcomes of numerical simulation on attainable performance.

  4. Kokkos Array

    SciTech Connect

    Edwards Daniel Sunderland, Harold Carter

    2012-09-12

    The Kokkos Array library implements shared-memory array data structures and parallel task dispatch interfaces for data-parallel computational kernels that are performance-portable to multicore-CPU and manycore-accelerator (e.g., GPGPU) devices.

  5. Nanoplasmonics tuned "click chemistry".

    PubMed

    Tijunelyte, I; Guenin, E; Lidgi-Guigui, N; Colas, F; Ibrahim, J; Toury, T; Lamy de la Chapelle, M

    2016-04-07

    Nanoplasmonics is a growing field of optical condensed matter science dedicated to optical phenomena at the nanoscale level in metal systems. Extensive research on noble metallic nanoparticles (NPs) has emerged within the last two decades due to their ability to keep the optical energy concentrated in the vicinity of NPs, in particular, the ability to create optical near-field enhancement followed by heat generation. We have exploited these properties in order to induce a localised "click" reaction in the vicinity of gold nanostructures under unfavourable experimental conditions. We demonstrate that this reaction can be controlled by the plasmonic properties of the nanostructures and we propose two physical mechanisms to interpret the observed plasmonic tuning of the "click" chemistry.

  6. Tune Variations due to Septum Stray Field F. Pederson &

    SciTech Connect

    Rinolfi, L.

    1986-10-12

    Two types of antiproton instabilities due to trapped ions are harmful in the AA. One is a coherent instability occurring when an ion pocket resonates with a 3-Q mode (hiccups), the other is excitation of 11th and 15th order non-linear resonances due to the non-linear focusing fields from localized ion clouds trapped in uncleared potential well pockets. Accumulation with a good injection yield of antiprotons forces us to locate the tune of the dense core in the general area of the array of 15th order resonances. To avoid harmful blow-up of the dense core the tune is located between the resonances 11Q{sub H} + 4Q{sub V} = 34, 10Q{sub H} + 5Q{sub V} = 34, and 11Q{sub H} = 25, requiring a tune of Q{sub H} = 2.2722 to be maintained with a precision of a few 10{sup -4} (Fig. 4). Different angles of the injection and ejection trajectories require the septum current to be changed from 3860 A during accumulation to 3920 A, during ejection mode. Variations in the septum stray field due to these changes in current cause tune changes in the order of 10{sup -3}. In addition, at a given septum current, a pronounced hysteresis of the stray field causes tune variations of about the same order of magnitude, so also the past history of the septum excitation must be carefully controlled to obtain a reproducible tune.

  7. Nanoplasmonics tuned ``click chemistry''

    NASA Astrophysics Data System (ADS)

    Tijunelyte, I.; Guenin, E.; Lidgi-Guigui, N.; Colas, F.; Ibrahim, J.; Toury, T.; Lamy de La Chapelle, M.

    2016-03-01

    Nanoplasmonics is a growing field of optical condensed matter science dedicated to optical phenomena at the nanoscale level in metal systems. Extensive research on noble metallic nanoparticles (NPs) has emerged within the last two decades due to their ability to keep the optical energy concentrated in the vicinity of NPs, in particular, the ability to create optical near-field enhancement followed by heat generation. We have exploited these properties in order to induce a localised ``click'' reaction in the vicinity of gold nanostructures under unfavourable experimental conditions. We demonstrate that this reaction can be controlled by the plasmonic properties of the nanostructures and we propose two physical mechanisms to interpret the observed plasmonic tuning of the ``click'' chemistry.Nanoplasmonics is a growing field of optical condensed matter science dedicated to optical phenomena at the nanoscale level in metal systems. Extensive research on noble metallic nanoparticles (NPs) has emerged within the last two decades due to their ability to keep the optical energy concentrated in the vicinity of NPs, in particular, the ability to create optical near-field enhancement followed by heat generation. We have exploited these properties in order to induce a localised ``click'' reaction in the vicinity of gold nanostructures under unfavourable experimental conditions. We demonstrate that this reaction can be controlled by the plasmonic properties of the nanostructures and we propose two physical mechanisms to interpret the observed plasmonic tuning of the ``click'' chemistry. Electronic supplementary information (ESI) available: NMR study on reaction initiation, SERS spectra and temperature calculations. See DOI: 10.1039/c5nr09018k

  8. Nanocylinder arrays

    DOEpatents

    Tuominen, Mark; Schotter, Joerg; Thurn-Albrecht, Thomas; Russell, Thomas P.

    2007-03-13

    Pathways to rapid and reliable fabrication of nanocylinder arrays are provided. Simple methods are described for the production of well-ordered arrays of nanopores, nanowires, and other materials. This is accomplished by orienting copolymer films and removing a component from the film to produce nanopores, that in turn, can be filled with materials to produce the arrays. The resulting arrays can be used to produce nanoscale media, devices, and systems.

  9. Nanocylinder arrays

    DOEpatents

    Tuominen, Mark; Schotter, Joerg; Thurn-Albrecht, Thomas; Russell, Thomas P.

    2009-08-11

    Pathways to rapid and reliable fabrication of nanocylinder arrays are provided. Simple methods are described for the production of well-ordered arrays of nanopores, nanowires, and other materials. This is accomplished by orienting copolymer films and removing a component from the film to produce nanopores, that in turn, can be filled with materials to produce the arrays. The resulting arrays can be used to produce nanoscale media, devices, and systems.

  10. Investigating a Quadrant Surface Coil Array for NQR Remote Sensing

    DTIC Science & Technology

    2014-10-23

    resonant at the same frequency. Coils will be in a “quadrant surface layout” in which all coils are in a four square arrangement to measure mutual ...Coil Array, probe, Nuclear Magnetic Resonance, tuning, decoupling, RLC, mutual coupling, RLC I. INTRODUCTION N Nuclear quadrupole resonance (NQR...same tuning to the 28.578MHz resonant frequency. III. QUADRANT MUTUAL COUPLING Now that the probes are tuned individually, the focus is now on

  11. Varactor tuned transistor oscillators /Survey/

    NASA Astrophysics Data System (ADS)

    Deriugin, I. A.; Kitaev, Iu. I.; Solodovnikov, N. P.

    1981-03-01

    Major developments in the theory and technology of varactor tuned solid state oscillators are surveyed on the basis of data appearing in periodical and patent literature. Attention is given to problems in general theory, modulation characteristics, transient processes occurring during tuning, stability properties, and circuit fabrication aspects.

  12. Fine-Grained, Local Maps and Coarse, Global Representations Support Human Spatial Working Memory

    PubMed Central

    Katshu, Mohammad Zia Ul Haq; d'Avossa, Giovanni

    2014-01-01

    While sensory processes are tuned to particular features, such as an object's specific location, color or orientation, visual working memory (vWM) is assumed to store information using representations, which generalize over a feature dimension. Additionally, current vWM models presume that different features or objects are stored independently. On the other hand, configurational effects, when observed, are supposed to mainly reflect encoding strategies. We show that the location of the target, relative to the display center and boundaries, and overall memory load influenced recall precision, indicating that, like sensory processes, capacity limited vWM resources are spatially tuned. When recalling one of three memory items the target distance from the display center was overestimated, similar to the error when only one item was memorized, but its distance from the memory items' average position was underestimated, showing that not only individual memory items' position, but also the global configuration of the memory array may be stored. Finally, presenting the non-target items at recall, consequently providing landmarks and configurational information, improved precision and accuracy of target recall. Similarly, when the non-target items were translated at recall, relative to their position in the initial display, a parallel displacement of the recalled target was observed. These findings suggest that fine-grained spatial information in vWM is represented in local maps whose resolution varies with distance from landmarks, such as the display center, while coarse representations are used to store the memory array configuration. Both these representations are updated at the time of recall. PMID:25259601

  13. Color-tuned channelrhodopsins for multiwavelength optogenetics.

    PubMed

    Prigge, Matthias; Schneider, Franziska; Tsunoda, Satoshi P; Shilyansky, Carrie; Wietek, Jonas; Deisseroth, Karl; Hegemann, Peter

    2012-09-14

    Channelrhodopsin-2 is a light-gated ion channel and a major tool of optogenetics. It is used to control neuronal activity via blue light. Here we describe the construction of color-tuned high efficiency channelrhodopsins (ChRs), based on chimeras of Chlamydomonas channelrhodopsin-1 and Volvox channelrhodopsin-1. These variants show superb expression and plasma membrane integration, resulting in 3-fold larger photocurrents in HEK cells compared with channelrhodopsin-2. Further molecular engineering gave rise to chimeric variants with absorption maxima ranging from 526 to 545 nm, dovetailing well with maxima of channelrhodopsin-2 derivatives ranging from 461 to 492 nm. Additional kinetic fine-tuning led to derivatives in which the lifetimes of the open state range from 19 ms to 5 s. Finally, combining green- with blue-absorbing variants allowed independent activation of two distinct neural cell populations at 560 and 405 nm. This novel panel of channelrhodopsin variants may serve as an important toolkit element for dual-color cell stimulation in neural circuits.

  14. Color-tuned Channelrhodopsins for Multiwavelength Optogenetics

    PubMed Central

    Prigge, Matthias; Schneider, Franziska; Tsunoda, Satoshi P.; Shilyansky, Carrie; Wietek, Jonas; Deisseroth, Karl; Hegemann, Peter

    2012-01-01

    Channelrhodopsin-2 is a light-gated ion channel and a major tool of optogenetics. It is used to control neuronal activity via blue light. Here we describe the construction of color-tuned high efficiency channelrhodopsins (ChRs), based on chimeras of Chlamydomonas channelrhodopsin-1 and Volvox channelrhodopsin-1. These variants show superb expression and plasma membrane integration, resulting in 3-fold larger photocurrents in HEK cells compared with channelrhodopsin-2. Further molecular engineering gave rise to chimeric variants with absorption maxima ranging from 526 to 545 nm, dovetailing well with maxima of channelrhodopsin-2 derivatives ranging from 461 to 492 nm. Additional kinetic fine-tuning led to derivatives in which the lifetimes of the open state range from 19 ms to 5 s. Finally, combining green- with blue-absorbing variants allowed independent activation of two distinct neural cell populations at 560 and 405 nm. This novel panel of channelrhodopsin variants may serve as an important toolkit element for dual-color cell stimulation in neural circuits. PMID:22843694

  15. Testing of Josephson Array Antennas and Trim Current Tuning

    DTIC Science & Technology

    2002-09-01

    Zhuravel ’, V. G. Efremenko, and B. B. Banduryan, Sov. J. Low Temp. Phys. 12, 311 (1986) [4] Yu. Ya. Divin, F. Ya. Nad’, V. Ya. Pokrovski, P. M...Shadrin, IEEE Transactions on Magnetics, 27, No.2, 1101 (1991) [5] A. G. Sivakov, A. P. Zhuravel ’, O. G. Turutanov, I. M. Dmitrenko, Appl. Surf. Sci. 106

  16. Gaussian Schell-model arrays.

    PubMed

    Mei, Zhangrong; Zhao, Daomu; Korotkova, Olga; Mao, Yonghua

    2015-12-01

    We introduce a novel class of planar, quasi-homogeneous Schell-model source for producing far fields with optical lattice average intensity patterns and derive the corresponding beam conditions. The array dimension, lobes intensity profile, and periodicity of the optical lattice can be flexibly tuned by changing the correlation parameters of the source field. It is also found that, with an appropriate choice of the source parameters, the radiant intensity may possess flat-topped intensity patterns.

  17. Plasmonic color tuning

    NASA Astrophysics Data System (ADS)

    Lee, Byoungho; Yun, Hansik; Lee, Seung-Yeol; Kim, Hwi

    2016-03-01

    In general, color filter is an optical component to permit the transmission of a specific color in cameras, displays, and microscopes. Each filter has its own unchangeable color because it is made by chemical materials such as dyes and pigments. Therefore, in order to express various colorful images in a display, one pixel should have three sub-pixels of red, green, and blue colors. Here, we suggest new plasmonic structure and method to change the color in a single pixel. It is comprised of a cavity and a metal nanoaperture. The optical cavity generally supports standing waves inside it, and various standing waves having different wavelength can be confined together in one cavity. On the other hand, although light cannot transmit sub-wavelength sized aperture, surface plasmons can propagate through the metal nanoaperture with high intensity due to the extraordinary transmission. If we combine the two structures, we can organize the spatial distribution of amplitudes according to wavelength of various standing waves using the cavity, and we can extract a light with specific wavelength and amplitude using the nanoaperture. Therefore, this cavity-aperture structure can simultaneously tune the color and intensity of the transmitted light through the single nanoaperture. We expect that the cavity-apertures have a potential for dynamic color pixels, micro-imaging system, and multiplexed sensors.

  18. Tuning the engine

    PubMed Central

    2012-01-01

    In the last years post-transcriptional regulation (PTR) of gene expression has been increasingly recognized to be a powerful and general determinant of the quantitative changes in proteomes, and therefore a driving force for cell phenotypes. By means of networks of trans-factors on one hand, and cis-elements found primarily in untranslated regions (UTRs) of mRNA on the other hand, mRNA availability to translation and translation rates are tightly controlled and can be rapidly tuned according to the changing state of the cell. A number of dedicated resources and tools, including databases and predictive algorithms, have been proposed as bioinformatics aids for the study of this fundamental layer of gene expression regulation. Their use, however, is rendered difficult by heterogeneity and fragmentation. This review aims to locate these resources in their proper space, classifying them according to their goals, limitations and integration capabilities and, in the end, to provide the user with an initial toolbox for the bioinformatic analysis of post-transcriptional regulation of gene expression. The accompanying website, available at www.ptrguide.org, lists all resources, provides summary and features for each one and will be regularly updated in the future. PMID:22995832

  19. Tuning surface plasmons in graphene ribbons with liquid crystal layer

    NASA Astrophysics Data System (ADS)

    Reshetnyak, Viktor Yu.; Bunning, Timothy J.; Evans, Dean R.

    2016-09-01

    Surface plasmons in graphene possess stronger mode confinement and lower propagation loss. One way to excite the surface plasmons is placing a periodic array of graphene nano-ribbons on top of a dielectric substrate. However once the system is fabricated it is not possible to change its optical properties. Liquid crystals (LC) are a uniaxial medium with an optical axis easily controlled by external stimuli. We suggest tuning the surface plasmons in an array of graphene ribbons by placing a LC slab on top of the ribbons. A voltage applied to the LC layer shifts the graphene ribbons plasmonic notch and changes its depth.

  20. Mississippi Fine Arts Framework.

    ERIC Educational Resources Information Center

    Mississippi State Dept. of Education, Jackson.

    The Mississippi Fine Arts Framework is designed to develop K-12 students' interest and expertise in dance, music, theater arts, and visual arts. The introductory fine arts course, for secondary level students, explores the relationship and the function of the arts in both historical and contemporary culture through creative projects, performance,…