1,742 research outputs found
How Prevalent is Functional Alternative Splicing in the
No full textthis article can be found at doi: 10.1016/j.tig.2003.12.004 Corresponding author: Gil Ast ([email protected]
Ant Colony Optimization for Control
No full textThe very basis of this thesis is the collective behavior of ants in colonies. Ants are an excellent example of how rather simple behavior on a local level can lead to complex behavior on a global level that is beneficial for the individuals. The key in the self-organization of ants is communication through pheromones. When an ant forages for food, it is biased to search along trails of stronger pheromone concentrations. The moment it finds food, it will walk back to the nest while depositing pheromones and thereby contributing to the reinforcement of a successful trail. Inspired by this mechanism, research within an engineering context has led to the development of the field of Ant Colony Optimization (ACO). Specifically developed for efficiently solving combinatorial optimization problems, ACO has been successfully applied to routing in road traffic and Internet networks. In this thesis, we take the principles behind ACO to the domain of control policy learning. A control policy is a mapping from states to actions and our objective is to develop methods to learn the optimal control policy for a given dynamic system by interacting with it. We call our methods Ant Colony Learning (ACL) and their power lies in the fact that there is a set of ants, from which each ant interacts with the system and influences the other ants through updating pheromone levels associated with the visited state-action pairs. In experiments involving control problems that have a discrete state space and deterministic state transitions, it turns out that ACL converges quickly to the optimal solution. We also observe that increasing the number of ants in the algorithm results in a decrease of the number of trials required for convergence to the optimal policy. An analytical study of the convergence behavior of ACL reveals that for systems with discrete and noiseless state transitions, the expected policy converges to the optimal policy in the case of using only one ant. Another major part of this thesis deals with the application of ACL to control problems with continuous state spaces. In order to capture a continuous space with a finite number of elements, we study two ways of partitioning the state space and their incorporation in the ACL framework. In crisp ACL, the state space is partitioned using bins. Each state measurement is assigned to exactly one bin, which leads to the introduction of discretization noise, rendering an originally deterministic system non-deterministic and restricting the performance of the algorithm. We find that a better way of partitioning the state space is by using fuzzy triangular membership functions. The continuous state measurement then belongs to multiple membership functions to a certain degree. With fuzzy partitioning, the continuity of the state variables is preserved and no non-determinism is introduced. We call this method fuzzy ACL. The developed generalized ACL algorithm unifies both crisp and fuzzy ACL. The behavior and performance of crisp and fuzzy ACL are further studied using simulation experiments. We study the influence of the local and global pheromone decay rates, the number of ants, and the density of the state space partitioning grid on the learning performance. Especially, the performance of crisp ACL improves for a small local pheromone decay rate, while fuzzy ACL outperforms crisp ACL over the whole line. In general, crisp ACL is much more sensitive to the choice of the pheromone decay parameters than fuzzy ACL. We find that using more ants leads to faster convergence, but that the number of ants does not need to be extremely large to obtain a satisfactory performance. With regard to the scaling of ACL, crisp ACL reveals a slow, but gradual improvement of the learning for an increasing state space partitioning density. Fuzzy ACL, on the other hand, improves more rapidly and requires fewer ants to learn a better control policy. Finally, we present a general modeling framework for swarms of moving agents. It turns out that ACL fits within this framework and as such can be unified with other swarm intelligence techniques. In the future, this could result in beneficial integration of elements from other swarm intelligence techniques into ACL, or the other way around.Delft Center for Systems and ControlMechanical, Maritime and Materials Engineerin
Mid-infrared galaxy morphology from the Spitzer survey of stellar structure in galaxies (S^4G): the imprint of the De Vaucouleurs revised Hubble-Sandage classification system at 3.6 μm
No full text© 2010. The American Astronomical Society. All rights reserved. Artículo firmado por 21 autores. We thank the referee for many helpful comments that improved the presentation of this paper. We also thank D.L. Block for additional comments and for pointing us to a useful reference, as well as the other members of the S^(4)G Team for helping to make the project possible. R.B. acknowledges the support of NSF grant AST 05-07140. K.S. acknowledges support from the National Radio Astronomy Observatory, which is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. E.A. and A.B. thank the Centre National d'Etudes Spatiales for financial support. K. L. M. acknowledges funding from the Peter and Patricia Gruber Foundation as the 2008 IAU Fellow, from the University of Portsmouth and from SEPnet (www.sepnet.ac.uk). H. S. and E. L. acknowledge the Academy of Finland for support. J.H.K. acknowledges support by the Instituto de Astrofísica de Canarias (312407). K.M.D. is supported by an NSF Astronomy and Astrophysics Postdoctoral Fellowship under award AST-0802399. A.G.dP. and J.C.M.M. are partially financed by the Spanish Programa Nacional de Astronomía y Astrofísica under grants AyA2006-02358 and AyA2009-10368, and by the Spanish MEC under the Consolider-Ingenio 2010 Program grant CSD2006-00070: first Science with the GTC.A.G.dP. is also financed by the Spanish Ramón y Cajal program. J.C.M.M. acknowledges the receipt of a Formación del Profesorado Universitario fellowship. S.C. is supported by a KASI Postdoctoral Fellowship. This work is based (in part) on archival data obtained with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology under a contract with NASA. Support for this work was provided by an award issued by JPL/Caltech. Funding for the OSUBSGS was provided by grants from the NSF (grants AST 92-17716 and AST 96-17006), with additional funding from the Ohio State University. Funding for the creation and distribution of the SDSS Archive has been provided by the Alfred P. Sloan Foundation, the Participating Institutions, NASA, NSF, the U.S. Department of Energy, the Japanese Monbukagakusho, and Max Planck Society. NED is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with NASA.Spitzer Space Telescope Infrared Array Camera imaging provides an opportunity to study all known morphological types of galaxies in the mid-IR at a depth significantly better than ground-based near-infrared and optical images. The goal of this study is to examine the imprint of the de Vaucouleurs classification volume in the 3.6 μm band, which is the best Spitzer waveband for galactic stellar mass morphology owing to its depth and its reddening-free sensitivity mainly to older stars. For this purpose, we have prepared classification images for 207 galaxies from the Spitzer archive, most of which are formally part of the Spitzer Survey of Stellar Structure in Galaxies (S^4G), a Spitzer post-cryogenic ("warm") mission Exploration Science Legacy Program survey of 2331 galaxies closer than 40 Mpc. For the purposes of morphology, the galaxies are interpreted as if the images are blue light, the historical waveband for classical galaxy classification studies. We find that 3.6 μm classifications are well correlated with blue-light classifications, to the point where the essential features of many galaxies look very similar in the two very different wavelength regimes. Drastic differences are found only for the most dusty galaxies. Consistent with a previous study by Eskridge et al., the main difference between blue-light and mid-IR types is an ≈1 stage interval difference for S0/a to Sbc or Sc galaxies, which tend to appear "earlier" in type at 3.6 μm due to the slightly increased prominence of the bulge, the reduced effects of extinction, and the reduced (but not completely eliminated) effect of the extreme population I stellar component. We present an atlas of all of the 207 galaxies analyzed here and bring attention to special features or galaxy types, such as nuclear rings, pseudobulges, flocculent spiral galaxies, I0 galaxies, double-stage and double-variety galaxies, and outer rings, that are particularly distinctive in the mid-IR.National Science Foundation (NSF)Centre National d'Etudes Spatiales (CNES)Peter and Patricia Gruber FoundationUniversity of PortsmouthSEPnetAcademy of FinlandInstituto de Astrofísica de Canarias (IAC)Programa Nacional de Astronomía y Astrofísica, MINECOMinisterio de Economía y Competitividad (MINECO); EspañaPrograma Ramón y CajalFormación del Profesorado Universitario fellowshipKASINational Aeronautics and Space Administration (NASA)JPL/CaltechOhio State UniversityAlfred P. Sloan FoundationU.S. Department of EnergyJapanese MonbukagakushoMax Planck SocietyDepto. de Física de la Tierra y AstrofísicaFac. de Ciencias FísicasTRUEpu
Regulation of alternative splicing through coupling with transcription and chromatin structure
No full textAlternative precursor messenger RNA (pre-mRNA) splicing plays a pivotal role in the flow of genetic information from DNA to proteins by expanding the coding capacity of genomes. Regulation of alternative splicing is as important as regulation of transcription to determine cell- and tissue-specific features, normal cell functioning, and responses of eukaryotic cells to external cues. Its importance is confirmed by the evolutionary conservation and diversification of alternative splicing and the fact that its deregulation causes hereditary disease and cancer. This review discusses the multiple layers of cotranscriptional regulation of alternative splicing in which chromatin structure, DNA methylation, histone marks, and nucleosome positioning play a fundamental role in providing a dynamic scaffold for interactions between the splicing and transcription machineries. We focus on evidence for how the kinetics of RNA polymerase II (RNAPII) elongation and the recruitment of splicing factors and adaptor proteins to chromatin components act in coordination to regulate alternative splicing.Fil: Naftelberg S. Sackler Medical School - Tel Aviv University; IsraelFil: Schor, Ignacio Esteban. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Fisiología, Biología Molecular y Neurociencias; ArgentinaFil: Ast, Gil. Sackler Medical School, Tel Aviv; IsraelFil: Kornblihtt, Alberto Rodolfo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Fisiología, Biología Molecular y Neurociencias; Argentin
Suzanne Jovet-Ast (8 février 1914, Paris - 22 février 2006, Biarritz)
No full textSuzanne Jovet-Ast (Paris, 8 February 1914 – Biarritz, 22 February 2006) devoted her life to botany and, especially, to bryology. In 1941, she joined the Laboratoire de Cryptogamie ([PC], Muséum national d’Histoire naturelle, Paris) as “assistant”, and achieved her career by the directorship of this laboratory (1975-1982). Retired in 1982, she continued working until her death. Interested in taxonomy and biogeography, she was a specialist of the genus Riccia. The author has taken the opportunity of this biography for giving some data on the evolution of the laboratory of Cryptogamy during the stay of Jovet- Ast. A complete list of the botanical works of Jovet-Ast including publication dates is given.</p
DIPOLE MOMENTS OF THE STATES OF FORMYL FLUORIDE AND DIFLUORODIAZIRINE
No full textAuthor Institution: Department of Chemistry, Harvard UniversityA study is made of the Stark effect on the high resolution electronic absorption spectra of formyl fluoride (HFCO) and difluorodiazirine . The transition involved is . From splittings of the rotational lines (using polarized exciting light) the dipole moment of the excited is determined. In addition the Stark effect is used as an aid in the assignment of the rotational spectrum
AST-120 ameliorates lowered exercise capacity and mitochondrial biogenesis in the skeletal muscle from mice with chronic kidney disease via reducing oxidative stress
No full textBackground. Exercise capacity and quality of life are markedly impaired in chronic kidney disease (CKD). Increased plasma uremic toxins such as indoxyl sulfate (IS), which induce oxidative stress, may be involved in this process. An oral adsorbent, AST-120, can reduce circulating IS, however, its effects on skeletal muscle and exercise capacity have not been investigated in CKD. Methods. Subtotal-nephrectomy or sham operation was performed in 8-week-old C57BL/6J mice. They were divided into two groups with or without 8% (w/w) of AST-120 in standard diet for 20 weeks. Sham, Sham + AST-120, CKD and CKD + AST-120 (n = 12, each group) were studied. We also conducted a C2C12 cell culture study to determine the direct effects of IS on oxidative stress. Results. Plasma IS levels were significantly increased in CKD compared with Sham (1.05 +/- 0.11 versus 0.21 +/- 0.03 mg/dL, P < 0.05), which was significantly ameliorated in CKD + AST120 (0.41 +/- 0.06 mg/dL). The running distance to exhaustion determined by treadmill tests was significantly reduced in CKD compared with Sham (267 +/- 17 versus 427 +/- 36 m, P < 0.05), and this reduction was also significantly ameliorated in CKD + AST-120 (407 +/- 38 m) without altering skeletal muscle weight. Citrate synthase activity and mitochondrial biogenesis gene were downregulated, and superoxide production was significantly increased in the skeletal muscle from CKD, and these changes were normalized in CKD + AST-120. Incubation of C2C12 cells with IS significantly increased NAD(P) H oxidase activity. Conclusions. The administration of AST-120 improved exercise capacity and mitochondrial biogenesis of skeletal muscle via reducing oxidative stress. AST-120 may be a novel therapeutic agent against exercise intolerance in CKD
FTMW STUDIES OF HYDROGEN-BONDED TRIMERS
No full text Work supported by NSF and PRF. T.J. Balle and W.H. Flygare, Rev. Sci. Instrum. 52, 33 (1981).Author Institution: Noyes Chemical Laboratory, University of IllinoisRotational spectra have been observed with a Flygare FTMW for a number of hydrogen-bonded trimers, most of which are linear and have the HCN dimer as a subunit. Spectroscopic constants have been determined, usually for several isotopic species of each trimer. Their values are given below for the Itain species. Symmetries, hydrogen-bond lengths and the separation of torsional and charge redistribution effects on the quarupolar hyperfine structure of will be discussed. [FIGURE
Training school counselors in Interpersonal Psychotherapy-Adolescent Skills Training (IPT-AST): an examination of barriers to and facilitators of implementation
No full textInitial evidence suggests that school counselors can be trained in evidence-based prevention programs and treatments; however, the application of these interventions in the school setting is influenced by a variety of factors, including characteristics of the intervention, the provider, and the organization. Understanding and attending to these factors is crucial to promoting the successful implementation of evidence-based interventions in school settings. This study examined the initial feasibility and acceptability of a training and implementation package for Interpersonal Psychotherapy – Adolescent Skills Training (IPT-AST), a school-based preventive intervention for adolescent depression. Participants consisted of 33 school counselors from middle and high schools in six school districts in New Jersey who were invited to receive training in IPT-AST. Approximately six months following the training, participants completed 20-30 minute individual, semi-structured interviews regarding a) whether or not they ran IPTAST groups, b) perceived barriers to and facilitators of implementation, and c) suggestions for improvements to the IPT-AST training package. Of the 33 counselors interviewed at six-month follow up, only one had implemented an IPT-AST group (with significant modifications), and two others had attempted to run a group together. About half of the participants (N=16) reported incorporating components of IPT-AST (e.g., communication skills, closeness circle), into their individual, group, or dyadic work. Participant responses highlighted numerous barriers to implementation of IPT-AST that generally grouped into six categories: 1) time, 2) support from school community, 3) fit with school priorities and needs, 4) logistics, 5) readiness for implementation, and 6) beliefs. The facilitators of implementation of IPT-AST groups, as reported by three participants, fell into similar categories: 1) support from school community, 2) logistics, 3) readiness for implementation, 4) beliefs, and 5) provider characteristics. Implications for future training and implementation efforts are discussed.Psy.D.Includes bibliographical referencesby Caroline Axelrod Mende
DIRECTION OF POLARIZATION OF TRANSITIONS.
No full textAuthor Institution: Department of Chemistry and Laboratory for Research on the Structure of Matter, University of Pennsylvania, PhiladelphiaPolarized absorption measurements have been made on benzophenone and substituted benzophenones of know crystal structure. It has been shown conclusively that the singlet transition in benzophenone is polarized parallel to the carbonyl direction, whereas in the case of 4,4-dimethoxybenzophenone the transition is polarized perpendicular to the carbonyl direction. The polarization of the singlet triplet transitions in these molecules has also been determined. The symmetries and structures of the singlet and triplet states will be discussed, as well as the vibronic nature of the transitions that are manifest in the low temperature spectra
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