Sample records for tatjana oja vello

  1. The nature of very low luminosity objects (VeLLOs)

    NASA Astrophysics Data System (ADS)

    Vorobyov, Eduard I.; Elbakyan, Vardan; Dunham, Michael M.; Guedel, Manuel

    2017-04-01

    Aims: The nature of very low luminosity objects (VeLLOs) with the internal luminosity Lobj ≤ 0.1 L⊙ is investigated by means of numerical modeling coupling the core collapse simulations with the stellar evolution calculations. Methods: The gravitational collapse of a large sample of model cores in the mass range 0.1-2.0 M⊙ is investigated. Numerical simulations were started at the pre-stellar phase and terminated at the end of the embedded phase when 90% of the initial core mass had been accreted onto the forming protostar plus disk system. The disk formation and evolution was studied using numerical hydrodynamics simulations, while the formation and evolution of the central star was calculated using a stellar evolution code. Three scenarios for mass accretion from the disk onto the star were considered: hybrid accretion in which a fraction of accreted energy absorbed by the protostar depends on the accretion rate, hot accretion wherein a fraction of accreted energy is constant, and cold accretion wherein all accretion energy is radiated away. Results: Our conclusions on the nature of VeLLOs depend crucially on the character of protostellar accretion. In the hybrid accretion scenario, most VeLLOs (90.6%) are expected to be the first hydrostatic cores (FHSCs) and only a small fraction (9.4%) are true protostars. In the hot accretion scenario, all VeLLOs are FHSCs due to overly high photospheric luminosity of protostars. In the cold accretion scenario, on the contrary, the majority of VeLLOs belong to the Class I phase of stellar evolution. The reason is that the stellar photospheric luminosity, which sets the floor for the total internal luminosity of a young star, is lower in cold accretion, thus enabling more VeLLOs in the protostellar stage. VeLLOs are relatively rare objects occupying 7%-11% of the total duration of the embedded phase and their masses do not exceed 0.3 M⊙. When compared with published observations inferring a fraction of VeLLOs in the

  2. The Nature of VeLLOs

    NASA Astrophysics Data System (ADS)

    Huard, Tracy L.; Pound, Marc W.; Mundy, Lee; Dunham, Michael

    2018-01-01

    Very Low Luminosity Objects (VeLLOs) are young stellar sources that are defined by luminosities less than 0.1 solar luminosity and rising mid-infrared spectral energy distributions. But, what exactly are they? Brown dwarfs or low-mass stars in formation? Systems exhibiting low accretion rates? Extremely young objects? We have completed an ALMA survey of 33 candidates in the nearby Serpens, Ophiuchus, and Lupus star-forming molecular clouds. Continuum emission at 1.3 mm, consistent with the presence of an inner envelope and/or disk, was detected toward 17 candidates, with at least 6 of these candidates exhibiting CO outflow emission, suggesting ongoing formation. We will present these observations and results, and discuss their implications concerning the nature of VeLLOs.

  3. Modulated Hebb-Oja learning rule--a method for principal subspace analysis.

    PubMed

    Jankovic, Marko V; Ogawa, Hidemitsu

    2006-03-01

    This paper presents analysis of the recently proposed modulated Hebb-Oja (MHO) method that performs linear mapping to a lower-dimensional subspace. Principal component subspace is the method that will be analyzed. Comparing to some other well-known methods for yielding principal component subspace (e.g., Oja's Subspace Learning Algorithm), the proposed method has one feature that could be seen as desirable from the biological point of view--synaptic efficacy learning rule does not need the explicit information about the value of the other efficacies to make individual efficacy modification. Also, the simplicity of the "neural circuits" that perform global computations and a fact that their number does not depend on the number of input and output neurons, could be seen as good features of the proposed method.

  4. Simple modification of Oja rule limits L1-norm of weight vector and leads to sparse connectivity.

    PubMed

    Aparin, Vladimir

    2012-03-01

    This letter describes a simple modification of the Oja learning rule, which asymptotically constrains the L1-norm of an input weight vector instead of the L2-norm as in the original rule. This constraining is local as opposed to commonly used instant normalizations, which require the knowledge of all input weights of a neuron to update each one of them individually. The proposed rule converges to a weight vector that is sparser (has more zero weights) than the vector learned by the original Oja rule with or without the zero bound, which could explain the developmental synaptic pruning.

  5. Mass Accretion Rate of Very Low Luminosity Objects

    NASA Astrophysics Data System (ADS)

    Sung, Ren-Shiang; Lai, Shih-Ping; Hsieh, Tien-Hao

    2013-08-01

    We propose to measure the mass accretion rate of six Very Low Luminosity Objects (VeLLOs) using Near-infrared Integral Spectrometer (NIFS). The extremely low luminosity of VeLLOs, L_int ≤ 0.1 L_⊙, was previously thought not existing in the nature because the typical accretion rate gives much larger accretion luminosity even for the lowest mass star (``Luminosity Problem''). The commonly accepted solution is that the accretion rate is not constant but episodic. Thus, VeLLOs could be interpreted as protostars being in the quiescent phase of accretion activities. However, there is no observational data directly measuring the mass accretion rate of VeLLOs. The main goal of this proposal is to examine such theory and directly measure the mass accretion rate of VeLLOs for the first time. We propose to measure the blue continuum excess (veiling) of the stellar spectrum, which is the most reliable method for measuring the accretion rate. The measurements have to be made in infrared due to the very high extinction for highly embedded protostars. Our proposal provide a first opportunity to explain the long time ``Luminosity Problem'' through the observational aspects, and Gemini is the only instrument that can provide accurate and high sensitivity infrared spectroscopy measurements within reasonably short time scale.

  6. Detection of Metallothionein in Javanese Medaka (Oryzias javanicus), Using a scFv-Immobilized Protein Chip

    PubMed Central

    Lee, Euiyeon; Jeon, Hyunjin; Kang, Chungwon; Woo, Seonock; Yum, Seungshic; Kwon, Youngeun

    2018-01-01

    Environmental pollution by various industrial chemicals and biological agents poses serious risks to human health. Especially, marine contamination by potentially toxic elements (PTEs) has become a global concern in recent years. Many efforts have been undertaken to monitor the PTE contamination of the aquatic environment. However, there are few approaches available to assess the PTE exposure of aquatic organisms. In this research, we developed a strategy to evaluate the heavy metal exposure of marine organisms, by measuring the expression levels of metallothionein protein derived from Oryzias javanicus (OjaMT). OjaMT is a biomarker of heavy metal exposure because the expression level increases upon heavy metal exposure. The developed assay is based on a real-time, label-free surface plasmon resonance (SPR) measurement. Anti-OjaMT antibody and anti-OjaMT single-chain fragment of variable region (scFv) were used as detection probes. Two types of SPR sensor chips were fabricated, by immobilizing antibody or Cys3-tagged scFv (scFv-Cys3) in a controlled orientation and were tested for in situ label-free OjaMT detection. Compared to the antibody-presenting sensor chips, the scFv-presenting sensor chips showed improved performance, displaying enhanced sensitivity and enabling semi-quantitative detection. The portable SPR system combined with scFv-immobilized sensor chips is expected to provide an excellent point-of-care testing system that can monitor target biomarkers in real time. PMID:29614840

  7. All Prime Contract Awards by State or Country, Place, and Contractor, FY83, Part 1 (Argentina-Goodyear, Arizona).

    DTIC Science & Technology

    1983-01-01

    C Z 5 2 2 5110 000 69 HAND TOOLS EDGED NONPOWERED 7 9 3 5 L 06 1 B 4 1 0 100 WAESCHEREI KRAUSE GERMANY 088616 0000 GY I L OJA37 2913 DAJA37-82-00210 B...0 27 WOLFGANG PRAYON GERMANY 090010 0000 GY I D OJA37 0369 DAJA37-82-DO261 B C 2 5 3 2 V212 000 S MOTOR PASSENGER SERVICE 7 9 4 5 L 06 1 B J 1 J 34

  8. Earth observations taken during STS-83 mission

    NASA Image and Video Library

    2016-08-24

    STS083-749-084 (4-8 April 1997) --- Laguna Oja De Liebre, Baja, gray whale breeding ground Laguna Oja De Liebre, Baja (Scammons Lagoon) is located on the west coast in the plains of the central Baja. This lagoon and others like it along the Baja coast are used for breeding grounds for the gray whale. One group of gray whales inhabits the Sea of Okhotsk in summer, migrating south in winter then breed off southern Korea. The other summers in the Bering and Chukchi seas and travels south to winter breeding grounds along the coast of Baja California. The gray whale was hunted almost to extinction by 1925 but was placed under complete international protection and since the 1940s has increased in numbers. The white grids seen in the photo are commercial salt ponds.

  9. Why Do Some Cores Remain Starless?

    NASA Astrophysics Data System (ADS)

    Anathpindika, S.

    2016-08-01

    Prestellar cores, by definition, are gravitationally bound but starless pockets of dense gas. Physical conditions that could render a core starless (in the local Universe) is the subject of investigation in this work. To this end, we studied the evolution of four starless cores, B68, L694-2, L1517B, L1689, and L1521F, a VeLLO. We demonstrate: (i) cores contracted in quasistatic manner over a timescale on the order of ~ 105 yr. Those that remained starless briefly acquired a centrally concentrated density configuration that mimicked the profile of a unstable BonnorEbert sphere before rebounding, (ii) three cores viz. L694-2, L1689-SMM16, and L1521F remained starless despite becoming thermally super-critical. By contrast, B68 and L1517B remained sub-critical; L1521F collapsed to become a VeLLO only when gas-cooling was enhanced by increasing the size of dust-grains. This result is robust, for other starless cores viz. B68, L694-2, L1517B, and L1689 could also be similarly induced to collapse. The temperature-profile of starless cores and those that collapsed was found to be radically different. While in the former type, only very close to the centre of a core was there any evidence of decline in gas temperature, by contrast, a core of the latter type developed a more uniformly cold interior. Our principle conclusions are: (a) thermal super-criticality of a core is insufficient to ensure it will become protostellar, (b) potential star-forming cores (the VeLLO L1521F here), could be experiencing dust-coagulation that must enhance gasdust coupling and in turn lower gas temperature, thereby assisting collapse. This also suggests, mere gravitational/virial boundedness of a core is insufficient to ensure it will form stars.

  10. Global Realities: Celebrating Our Differences, Honoring Our Connections.

    ERIC Educational Resources Information Center

    Walz, Garry R., Ed.; Knowdell, Richard L., Ed.

    This publication contains papers based on program presentations from the 2003 International Career Development Conference. Chapters include: (1) How to Turn Your Passion into a Profit (S. Abbott); (2) Harnessing the Power of Career Transition Groups (M. Adoradio and A. Oja); (3) All the Worlds a Stage Using Theatre in Career Counseling (P.…

  11. Effects of Dose Frequency of Early Communication Intervention in Young Children with and without Down Syndrome

    ERIC Educational Resources Information Center

    Yoder, Paul; Woynaroski, Tiffany; Fey, Marc; Warren, Steven

    2014-01-01

    Children with intellectual disability were randomly assigned to receive Milieu Communication Teaching (MCT) at one 1-hr session per week (low dose frequency, LDF) or five 1-hr sessions per week (high dose frequency, HDF) over 9 months (Fey, Yoder, Warren, & Bredin-Oja, 2013. Non-Down syndrome (NDS) and Down syndrome (DS) subgroups were matched…

  12. Photoinduced Electronic Energy Transfer: Theoretical and Experimental Issues for Light Harvesting Applications

    DTIC Science & Technology

    2013-10-21

    PHOTOINDUCED ELECTRONIC ENERGY TRANSFER - THEORETICAL AND EXPERIMENTAL ISSUES FOR LIGHT HARVESTING APPLICATIONS PAUL BRUMER UNIV OF TORONTO 10/21... Applications 5a. CONTRACT NUMBER 5b. GRANT NUMBER FA9550-10-1-0260 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT...Harvesting Applications Grant Number: FA9550-10-1-0260 Program Manager: Dr. Tatjana Curcic, AFOSR Stated aims of the project

  13. Refractive Index Enhancement in Gases

    DTIC Science & Technology

    2012-02-29

    Associate Professor Deniz D. Yavuz Graduate Ph. D. Students: Nick Proite, Tyler Green, Dan Sikes, Zach Simmons, and Jared Miles Se. TASK NUMBER Sf...NUMBER OF PAGES 8 19a. NAME OF RESPONSIBLE PERSON Assoc. Prof. Deniz D. Yavuz 19b. TELEPHONE NUMBER (Include area code) Reset 608-263-9399...Refractive Index Enhancement in Gases Grant/Contract Number: FA9550-09-1-0124 Program Manager: Tatjana Curcic Principal Investigator: Deniz D. Yavuz Our

  14. Surface Observation Climatic Summaries (SOCS) for March AFB, California

    DTIC Science & Technology

    1989-11-01

    ANl , IL U’T4MMAkIZEU AS FOLLOWS: BY EIGAT 3 4OjA STANDARD) TIME PEK~ l . * LALII MONfl (AL, (LAP,-. !3NE) *BY MONTH (ALL TEARS AWL’ .lL - ~k 4-b;NfT...09 11 i .. 4t MS U 1 6034 2610 42 1095812-14. 75.3 13.679 10959 0 0 8227 4224 1409 10959 15-17’ 73.8 13.216 10957 0 0 7928 3897 96i 10957 18-20 ,,.8

  15. Magnetic field structure around cores with very low luminosity objects

    NASA Astrophysics Data System (ADS)

    Soam, A.; Maheswar, G.; Lee, Chang Won; Dib, Sami; Bhatt, H. C.; Tamura, Motohide; Kim, Gwanjeong

    2015-01-01

    Aims: We carried out optical polarimetry of five dense cores, (IRAM 04191, L1521F, L328, L673-7, and L1014) which are found to harbour very low luminosity objects (VeLLOs; Lint ≲ 0.1 L⊙). This study was conducted mainly to understand the role played by the magnetic field in the formation of very low and substellar mass range objects. Methods: Light from the stars, while passing through the dust grains that are aligned with their short axis parallel to an external magnetic field, becomes linearly polarised. The polarisation position angles measured for the stars can provide the plane-of-the sky magnetic field orientation. Because the light in the optical wavelength range is most efficiently polarised by the dust grains typically found at the outer layers of the molecular clouds, optical polarimetry mostly traces the magnetic field orientation of the core envelope. Results: The polarisation observations of stars projected on IRAM 04191, L328, L673-7, and L1014 were obtained in the R-band and those of L1521F were obtained in the V-band. The angular offsets between the envelope magnetic field direction (inferred from optical polarisation measurements) and the outflow position angles from the VeLLOs in IRAM 04191, L1521F, L328, L673-7, and L1014 are found to be 84°, 53°, 24°, 08°, and 15°, respectively. The mean value of the offsets for all the five clouds is ~ 37°. If we exclude IRAM 04191, the mean value reduces to become ~ 25°. In IRAM 04191, the offset between the projected envelope and the inner magnetic field (inferred from the submillimetre data obtained using SCUBA-POL) is found to be ~ 68°. The inner magnetic field, however, is found to be nearly aligned with the projected position angles of the minor axis, the rotation axis of the cloud, and the outflow from the IRAM 04191-IRS. We discuss a possible explanation for the nearly perpendicular orientation between the envelope and core scale magnetic fields in IRAM 04191. The angular offset between the

  16. IRAS 16253–2429: THE FIRST PROTO-BROWN DWARF BINARY CANDIDATE IDENTIFIED THROUGH THE DYNAMICS OF JETS

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Hsieh, Tien-Hao; Lai, Shih-Ping; Belloche, Arnaud

    2016-07-20

    The formation mechanism of brown dwarfs (BDs) is one of the long-standing problems in star formation because the typical Jeans mass in molecular clouds is too large to form these substellar objects. To answer this question, it is crucial to study a BD in the embedded phase. IRAS 16253–2429 is classified as a very low-luminosity object (VeLLO) with an internal luminosity of <0.1 L {sub ⊙}. VeLLOs are believed to be very low-mass protostars or even proto-BDs. We observed the jet/outflow driven by IRAS 16253–2429 in CO (2–1), (6–5), and (7–6) using the IRAM 30 m and Atacama Pathfinder Experimentmore » telescopes and the Submillimeter Array (SMA) in order to study its dynamical features and physical properties. Our SMA map reveals two protostellar jets, indicating the existence of a proto-binary system as implied by the precessing jet detected in H{sub 2} emission. We detect a wiggling pattern in the position–velocity diagrams along the jet axes, which is likely due to the binary orbital motion. Based on this information, we derive the current mass of the binary as ∼0.032 M{sub ⊙}. Given the low envelope mass, IRAS 16253–2429 will form a binary that probably consist of one or two BDs. Furthermore, we found that the outflow force as well as the mass accretion rate are very low based on the multi-transition CO observations, which suggests that the final masses of the binary components are at the stellar/substellar boundary. Since IRAS 16253 is located in an isolated environment, we suggest that BDs can form through fragmentation and collapse, similar to low-mass stars.« less

  17. VLA Ammonia Observations of IRAS 16253-2429: A Very Young and Low Mass Protostellar System

    NASA Technical Reports Server (NTRS)

    Wiseman, Jennifer J.

    2011-01-01

    IRAS l6253-2429. the source of the Wasp-Waist Nebula seen in Spitzer IRAC images, is an isolated very low luminosity ("VeLLO") Class 0 protostar in the nearby rho Ophiuchi cloud. We present VLA ammonia mapping observations of the dense gas envelope feeding the central core accreting system. We find a flattened envelope perpendicular to the outflow axis, and gas cavities that appear to cradle the outflow lobes as though carved out by the flow and associated (apparently precessing) jet. Based on the NH3 (1,1) and (2,2) emission distribution, we derive the mass, velocity fields and temperature distribution for the envelope. We discuss the combined evidence for this source as possibly one of the youngest and lowest mass sources in formation yet known.

  18. M-X Environmental Technical Report. Socioeconomic Impact Estimates for New Mexico ROI Counties. Detailed Tables.

    DTIC Science & Technology

    1980-12-22

    I - I l r 0(nMr P I I 0 i I ’. !s.IV 0 nI W I I I - I W I 4’ l PO a.4 C’) In I CV a M 1I 00 rAVV - V) oj~A" .0. i 1I I10...W %n D a ta E n te re d) R E ADI N S T R U C T I O N S REPORT DOCUMENTATION PAGE READ INSTRUCTIONS BEFORE COMPLETING FORM 1. REPORT NUMBER 12. GOVT...report relate to the following areas: (continued on reverse) DD , oANF 1473 EDITION OF I NOV 6S IS OBSOLETE

  19. Earth observations taken from Space Shuttle Columbia during STS-93 mission

    NASA Image and Video Library

    1999-07-23

    STS093-704-087 (23-27 July 1999) --- This low angle, early morning shot over Chile was photographed from the Earth-orbiting Space Shuttle Columbia during the STS-93 mission. In the words of one of the scientists studying the STS-93 Earth imagery, Laguna Verde, in the Atacama Province of Chile (near the Argentine border), lies like a turquoise jewel among the stark black and white snow covered volcanic peaks of the High Andes. The ambient elevation in this part of the Andes is 16,000 feet (4,877 meters) with the highest local peak, Nevada Ojas de Salado (just to the right of the lake), reaching to 23,240 feet. (7084 meters.)

  20. Excitement and synchronization of small-world neuronal networks with short-term synaptic plasticity.

    PubMed

    Han, Fang; Wiercigroch, Marian; Fang, Jian-An; Wang, Zhijie

    2011-10-01

    Excitement and synchronization of electrically and chemically coupled Newman-Watts (NW) small-world neuronal networks with a short-term synaptic plasticity described by a modified Oja learning rule are investigated. For each type of neuronal network, the variation properties of synaptic weights are examined first. Then the effects of the learning rate, the coupling strength and the shortcut-adding probability on excitement and synchronization of the neuronal network are studied. It is shown that the synaptic learning suppresses the over-excitement, helps synchronization for the electrically coupled network but impairs synchronization for the chemically coupled one. Both the introduction of shortcuts and the increase of the coupling strength improve synchronization and they are helpful in increasing the excitement for the chemically coupled network, but have little effect on the excitement of the electrically coupled one.

  1. A new modulated Hebbian learning rule--biologically plausible method for local computation of a principal subspace.

    PubMed

    Jankovic, Marko; Ogawa, Hidemitsu

    2003-08-01

    This paper presents one possible implementation of a transformation that performs linear mapping to a lower-dimensional subspace. Principal component subspace will be the one that will be analyzed. Idea implemented in this paper represents generalization of the recently proposed infinity OH neural method for principal component extraction. The calculations in the newly proposed method are performed locally--a feature which is usually considered as desirable from the biological point of view. Comparing to some other wellknown methods, proposed synaptic efficacy learning rule requires less information about the value of the other efficacies to make single efficacy modification. Synaptic efficacies are modified by implementation of Modulated Hebb-type (MH) learning rule. Slightly modified MH algorithm named Modulated Hebb Oja (MHO) algorithm, will be also introduced. Structural similarity of the proposed network with part of the retinal circuit will be presented, too.

  2. Holloman AFB, New Mexico. Revised Uniform Summary of Surface Weather Observations (RUSSWO). Parts A-F.

    DTIC Science & Technology

    1982-04-12

    A RC ..... sl6 3i4 ~ N0 A.o 0 o2 *I A3 05 .7 0 to TRACE A 5S :S TRAC .29 .0.0 *2.. *,.j st16 &TRC T ACt la S4 :01 o Ŕ TRAC risAc *4 ?P.TAC *I .0 .02...2l 046 t.2 145 .14 TRACE TRACI T*A TRI 004....~ 60 A001. sOJa .. , 46 .31 .04 .01 6 at .0 .2 .10 47 1_ 1_ - -A .121 __ 48 1.2 .61 .0 TRAC 2.9 l.9 al...r - sea--vu 6s 23.6 *7.6 20 1 9 26 1.9 7 02__1 wo 10mS 0 .5 02U*1*7 9 w 91 "m,. om .4FVC%. LA ~im wm ul 19 292 Ze* ~ U -A- GLiCBAL CLIMATOLOGY

  3. Noch ein "Geheimnis des Jazz": Saying "Oja" to Afro-German Studies.

    ERIC Educational Resources Information Center

    Divers, Greg

    1995-01-01

    Introduces classroom materials with which African American students who are studying German can identify. The article shows that contemporary German poetry and the work of African American poets in German translation offer many possibilities for exercises that speak directly to African American students at all levels. (25 references) (Author/CK)

  4. Independet Component Analyses of Ground-based Exoplanetary Transits

    NASA Astrophysics Data System (ADS)

    Silva Martins-Filho, Walter; Griffith, Caitlin Ann; Pearson, Kyle; Waldmann, Ingo; Biddle, Lauren; Zellem, Robert Thomas; Alvarez-Candal, Alvaro

    2016-10-01

    Most observations of exoplanetary atmospheres are conducted when a "Hot Jupiter" exoplanet transits in front of its host star. These Jovian-sized planets have small orbital periods, on the order of days, and therefore a short transit time, making them more ameanable to observations. Measurements of Hot Jupiter transits must achieve a 10-4 level of accuracy in the flux to determine the spectral modulations of the exoplanetary atmosphere. In order to accomplish this level of precision, we need to extract systematic errors, and, for ground-based measurements, the effects of Earth's atmosphere, from the signal due to the exoplanet, which is several orders of magnitudes smaller. Currently, the effects of the terrestrial atmosphere and the some of the time-dependent systematic errors are treated by dividing the host star by a reference star at each wavelength and time step of the transit. More recently, Independent Component Analyses (ICA) have been used to remove systematic effects from the raw data of space-based observations (Waldmann 2014,2012; Morello et al.,2015,2016). ICA is a statistical method born from the ideas of the blind-source separation studies, which can be used to de-trend several independent source signals of a data set (Hyvarinen and Oja, 2000). One strength of this method is that it requires no additional prior knowledge of the system. Here, we present a study of the application of ICA to ground-based transit observations of extrasolar planets, which are affected by Earth's atmosphere. We analyze photometric data of two extrasolar planets, WASP-1b and GJ3470b, recorded by the 61" Kuiper Telescope at Stewart Observatory using the Harris B and U filters. The presentation will compare the light curve depths and their dispersions as derived from the ICA analysis to those derived by analyses that ratio of the host star to nearby reference stars.References: Waldmann, I.P. 2012 ApJ, 747, 12, Waldamann, I. P. 2014 ApJ, 780, 23; Morello G. 2015 ApJ, 806

  5. Extremely Low Mass: The Circumstellar Envelope of a Potential Proto-Brown Dwarf

    NASA Technical Reports Server (NTRS)

    Wiseman, Jennifer

    2011-01-01

    What is the environment for planet formation around extremely low mass stars? Is the environment around brown dwarfs and extremely low mass stars conducive and sufficiently massive for planet production? The determining conditions may be set very early in the process of the host object's formation. IRAS 16253-2429, the source of the Wasp-Waist Nebula seen in Spitzer IRAC images, is an isolated, very low luminosity ("VeLLO") Class 0 protostar in the nearby rho Ophiuchi cloud. We present VLA ammonia mapping observations of the dense gas envelope feeding the central core accreting system. We find a flattened envelope perpendicular to the outflow axis, and gas cavities that appear to cradle the outflow lobes as though carved out by the flow and associated (apparently precessing) jet, indicating environmental disruption. Based on the NH3 (1,1) and (2,2) emission distribution, we derive the mass, velocity fields and temperature distribution for the envelope. We discuss the combined evidence for this source to be one of the youngest and lowest mass sources in formation yet known, and discuss the ramifications for planet formation potential in this extremely low mass system.

  6. VizieR Online Data Catalog: Very Low-Luminosity Objects (VeLLOs) from 1.25-850um (Kim+, 2016)

    NASA Astrophysics Data System (ADS)

    Kim, M.-R.; Lee, C. W.; Dunham, M. M.; Evans, N. J., II; Kim, G.; Allen, L. E.

    2016-10-01

    The Spitzer Gould Belt Survey (GBS) is a project to survey about 21 square degrees of 11 nearby molecular clouds at 3.6-160um to provide a census of star formation in nearby large clouds (P.I. L. Allen). Spitzer has mapped a total of 11 molecular clouds, CMC, Chamaeleon I, Chamaeleon III, Musca, Lupus V, Lupus VI, Ophiuchus North, Aquila, CrA, Cepheus, and IC 5146 with the IRAC and MIPS between 2004 March and 2008 October. We utilized the data provided by the c2d/GBS projects (Evans et al. 2009, J/ApJS/181/321; Dunham et al. 2015, J/ApJS/220/11). There are two cloud complexes which were not listed in the c2d/GBS projects, but observed by other projects, the Taurus molecular clouds and the Orion molecular clouds. The Taurus molecular clouds have been observed over an area of ~44 square degrees by one of the GTO programs (P.I. D. Padgett) with the IRAC and the MIPS instruments. The Orion molecular clouds have been surveyed in ~9°2 area by Spitzer (P.I. T. Megeath). See section 2.1 for further details. Complementary archive infrared data were retrieved from 2MASS and Herschel PACS and SPIRE and JCMT SCUBA-2; see section 2.2. We observed our sources with the N2H+(1-0) line with the Korean Very Long Baseline Interferometry Network (KVN) 21m radio telescopes from 2011 October to 2016 May for the northern hemisphere sources, and the Mopra 22m telescope in 2012 April for the southern hemisphere sources. See section 2.3 for further explanations. (8 data files).

  7. A critical review of concept of aging in Ayurveda

    PubMed Central

    Devi, Durgawati; Srivastava, Rajeev; Dwivedi, B. K.

    2010-01-01

    Ayurveda has a holistic approach toward all the miseries of man and aging is one of these. It is classified as one of the natural and Yapya (palliative) diseases. It is the process of becoming old and decaying. As age advances, several changes take place in the body, in the external appearance, in the condition of Dosha, Dhatu, Mala, Agni, Oja, and so on, as well as in the mental and cognitive functions. Elderly people are susceptible to several chronic diseases also. The problems of the elderly are becoming a matter of great concern as increased life expectancy due to better medical services and improved technology is resulting in an increasing population of the aged. By the year 2020, the World will have more than one billion people aged 60 and over, and more than two-thirds of them will be living in the developing countries. A major concern related to the rapid increase in the population of the aged is that there will be an increase in the prevalence of chronic diseases and disabilities, both being conditions that tend to accompany the aging process. This burden is increasing day by day. In the Ayurvedic texts, a comprehensive description has been given of aging. The aim of this conceptual article is to compile and re-evaluate the various principles related to different aspects of aging. PMID:22048551

  8. Algorithms for accelerated convergence of adaptive PCA.

    PubMed

    Chatterjee, C; Kang, Z; Roychowdhury, V P

    2000-01-01

    We derive and discuss new adaptive algorithms for principal component analysis (PCA) that are shown to converge faster than the traditional PCA algorithms due to Oja, Sanger, and Xu. It is well known that traditional PCA algorithms that are derived by using gradient descent on an objective function are slow to converge. Furthermore, the convergence of these algorithms depends on appropriate choices of the gain sequences. Since online applications demand faster convergence and an automatic selection of gains, we present new adaptive algorithms to solve these problems. We first present an unconstrained objective function, which can be minimized to obtain the principal components. We derive adaptive algorithms from this objective function by using: 1) gradient descent; 2) steepest descent; 3) conjugate direction; and 4) Newton-Raphson methods. Although gradient descent produces Xu's LMSER algorithm, the steepest descent, conjugate direction, and Newton-Raphson methods produce new adaptive algorithms for PCA. We also provide a discussion on the landscape of the objective function, and present a global convergence proof of the adaptive gradient descent PCA algorithm using stochastic approximation theory. Extensive experiments with stationary and nonstationary multidimensional Gaussian sequences show faster convergence of the new algorithms over the traditional gradient descent methods.We also compare the steepest descent adaptive algorithm with state-of-the-art methods on stationary and nonstationary sequences.

  9. Conceptual analysis of diabetic retinopathy in Ayurveda.

    PubMed

    Sahoo, Prasanta Kumar; Fiaz, Shamsa

    Inclusion of Prameha among the eight major disorders in Charaka Samhita shows the importance of the disease given by ancient seers. The risk of development of blindness in diabetics increases by 20-25 times as compared to the normal population. High prevalence rate of Diabetic Retinopathy (34.6%), proliferative diabetic retinopathy (7%), diabetic macular edema (6.8%), and Vision threatening Diabetic retinopathy (10.2%) in diabetics was great concerns which led to search and analyze the disease process on the basis of modern pathogenesis and different Timirvyadhi mentioned in Ayurvedic authoritative texts. Thus the present study endeavors to discuss the similarities and differences among the various components of Prameha/Madhumehajanya Timir with Diabetic retinopathy and its stages. To establish a probable etiopathogenesis of the disease from Ayurveda prospective, all the important literature of both modern medicine and Ayurveda along with online sources were searched and analyzed. All the three dosha along with Raktadosha and Saptadhatu with four internal Dristipatals of eye are affected in Madhumehajanya timir in different stages of the disease. Avarana and Dhatu kshaya too have important role in development of diabetic retinopathy due to prolonged and uncontrolled hyperglycemia. Agnimandya related Ama formation has a role in pathology of diabetic retinopathy which is quite similar to oxidative theory of diabetic retinopathy explained in modern pathology. Urdhwaga raktapitta, Ojas kshaya, Raktavritta vata, and Pranavritta vyana are other causes in development of diabetic retinopathy. Copyright © 2017 Transdisciplinary University, Bangalore and World Ayurveda Foundation. Published by Elsevier B.V. All rights reserved.

  10. 3D numerical calculations and synthetic observations of magnetized massive dense core collapse and fragmentation.

    NASA Astrophysics Data System (ADS)

    Commerçon, B.; Hennebelle, P.; Levrier, F.; Launhardt, R.; Henning, Th.

    2012-03-01

    I will present radiation-magneto-hydrodynamics calculations of low-mass and massive dense core collapse, focusing on the first collapse and the first hydrostatic core (first Larson core) formation. The influence of magnetic field and initial mass on the fragmentation properties will be investigated. In the first part reporting low mass dense core collapse calculations, synthetic observations of spectral energy distributions will be derived, as well as classical observational quantities such as bolometric temperature and luminosity. I will show how the dust continuum can help to target first hydrostatic cores and to state about the nature of VeLLOs. Last, I will present synthetic ALMA observation predictions of first hydrostatic cores which may give an answer, if not definitive, to the fragmentation issue at the early Class 0 stage. In the second part, I will report the results of radiation-magneto-hydrodynamics calculations in the context of high mass star formation, using for the first time a self-consistent model for photon emission (i.e. via thermal emission and in radiative shocks) and with the high resolution necessary to resolve properly magnetic braking effects and radiative shocks on scales <100 AU (Commercon, Hennebelle & Henning ApJL 2011). In this study, we investigate the combined effects of magnetic field, turbulence, and radiative transfer on the early phases of the collapse and the fragmentation of massive dense cores (M=100 M_⊙). We identify a new mechanism that inhibits initial fragmentation of massive dense cores, where magnetic field and radiative transfer interplay. We show that this interplay becomes stronger as the magnetic field strength increases. We speculate that highly magnetized massive dense cores are good candidates for isolated massive star formation, while moderately magnetized massive dense cores are more appropriate to form OB associations or small star clusters. Finally we will also present synthetic observations of these

  11. Independent Component Analysis applied to Ground-based observations

    NASA Astrophysics Data System (ADS)

    Martins-Filho, Walter; Griffith, Caitlin; Pearson, Kyle; Waldmann, Ingo; Alvarez-Candal, Alvaro; Zellem, Robert Thomas

    2018-01-01

    Transit measurements of Jovian-sized exoplanetary atmospheres allow one to study the composition of exoplanets, largely independent of the planet’s temperature profile. However, measurements of hot-Jupiter transits must archive a level of accuracy in the flux to determine the spectral modulation of the exoplanetary atmosphere. To accomplish this level of precision, we need to extract systematic errors, and, for ground-based measurements, the effects of Earth’s atmosphere, from signal due to the exoplanet, which is several orders of magnitude smaller. The effects of the terrestrial atmosphere and some of the time-dependent systematic errors of ground-based transit measurements are treated mainly by dividing the host star by a reference star at each wavelength and time step of the transit. Recently, Independent Component Analysis (ICA) have been used to remove systematics effects from the raw data of space-based observations (Waldmann, 2014, 2012; Morello et al., 2016, 2015). ICA is a statistical method born from the ideas of the blind-source separations studies, which can be used to de-trend several independent source signals of a data set (Hyvarinen and Oja, 2000). This technique requires no additional prior knowledge of the data set. In addition, this technique has the advantage of requiring no reference star. Here we apply the ICA to ground-based photometry of the exoplanet XO-2b recorded by the 61” Kuiper Telescope and compare the results of the ICA to those of a previous analysis from Zellem et al. (2015), which does not use ICA. We also simulate the effects of various conditions (concerning the systematic errors, noise and the stability of object on the detector) to determine the conditions under which an ICA can be used with high precision to extract the light curve of exoplanetary photometry measurements

  12. Action spectra of photosystems II and I and quantum yield of photosynthesis in leaves in State 1.

    PubMed

    Laisk, Agu; Oja, Vello; Eichelmann, Hillar; Dall'Osto, Luca

    2014-02-01

    The spectral global quantum yield (YII, electrons/photons absorbed) of photosystem II (PSII) was measured in sunflower leaves in State 1 using monochromatic light. The global quantum yield of PSI (YI) was measured using low-intensity monochromatic light flashes and the associated transmittance change at 810nm. The 810-nm signal change was calibrated based on the number of electrons generated by PSII during the flash (4·O2 evolution) which arrived at the PSI donor side after a delay of 2ms. The intrinsic quantum yield of PSI (yI, electrons per photon absorbed by PSI) was measured at 712nm, where photon absorption by PSII was small. The results were used to resolve the individual spectra of the excitation partitioning coefficients between PSI (aI) and PSII (aII) in leaves. For comparison, pigment-protein complexes for PSII and PSI were isolated, separated by sucrose density ultracentrifugation, and their optical density was measured. A good correlation was obtained for the spectral excitation partitioning coefficients measured by these different methods. The intrinsic yield of PSI was high (yI=0.88), but it absorbed only about 1/3 of quanta; consequently, about 2/3 of quanta were absorbed by PSII, but processed with the low intrinsic yield yII=0.63. In PSII, the quantum yield of charge separation was 0.89 as detected by variable fluorescence Fv/Fm, but 29% of separated charges recombined (Laisk A, Eichelmann H and Oja V, Photosynth. Res. 113, 145-155). At wavelengths less than 580nm about 30% of excitation is absorbed by pigments poorly connected to either photosystem, most likely carotenoids bound in pigment-protein complexes. Copyright © 2013 Elsevier B.V. All rights reserved.

  13. Independent Component Analysis applied to Ground-based observations

    NASA Astrophysics Data System (ADS)

    Martins-Filho, Walter; Griffith, Caitlin Ann; Pearson, Kyle; Waldmann, Ingo; Alvarez-Candal, Alvaro; Zellem, Robert

    2017-10-01

    Transit measurements of Jovian-sized exoplanetary atmospheres allow one to study the composition of exoplanets, largely independent of the planet’s temperature profile. However, measurements of hot-Jupiter transits must archive a level of accuracy in the flux to determine the spectral modulations of the exoplanetary atmosphere. To accomplish this level of precision, we need to extract systematic errors, and, for ground-based measurements, the effects of Earth’s atmosphere, from signal due to the exoplanet, which is several orders of magnitudes smaller.The effects of the terrestrial atmosphere and some of the time dependent systematic errors of ground-based transit measurements are treated mainly by dividing the host star by a reference star at each wavelength and time step of the transit. Recently, Independent Component Analyses (ICA) have been used to remove systematics effects from the raw data of space-based observations (Waldmann, 2014, 2012; Morello et al., 2016, 2015). ICA is a statistical method born from the ideas of the blind-source separations studies, which can be used to de-trend several independent source signals of a data set (Hyvarinen and Oja, 2000). This technique requires no additional prior knowledge of the data set. In addition this technique has the advantage of requiring no reference star.Here we apply the ICA to ground-based photometry of the exoplanet XO-2b recorded by the 61” Kuiper Telescope and compare the results of the ICA to those of a previous analysis from Zellem et al. (2015), which does not use ICA. We also simulate the effects of various conditions (concerning the systematic errors, noise and the stability of object on the detector) to determine the conditions under which an ICA can be used with high precision to extract the light curve of exoplanetary photometry measurements.

  14. PREFACE: 2nd International Conference on Innovative Materials, Structures and Technologies

    NASA Astrophysics Data System (ADS)

    Ručevskis, Sandris

    2015-11-01

    Bajare, Laura Sele, Liga Radina and Jana Galilejeva for their major contribution to organizing the conference and to the literary editor Tatjana Smirnova and technical editor Daira Erdmane for their hard work on the conference proceedings.

  15. Lagrange constraint neural network for audio varying BSS

    NASA Astrophysics Data System (ADS)

    Szu, Harold H.; Hsu, Charles C.

    2002-03-01

    Lagrange Constraint Neural Network (LCNN) is a statistical-mechanical ab-initio model without assuming the artificial neural network (ANN) model at all but derived it from the first principle of Hamilton and Lagrange Methodology: H(S,A)= f(S)- (lambda) C(s,A(x,t)) that incorporates measurement constraint C(S,A(x,t))= (lambda) ([A]S-X)+((lambda) 0-1)((Sigma) isi -1) using the vector Lagrange multiplier-(lambda) and a- priori Shannon Entropy f(S) = -(Sigma) i si log si as the Contrast function of unknown number of independent sources si. Szu et al. have first solved in 1997 the general Blind Source Separation (BSS) problem for spatial-temporal varying mixing matrix for the real world remote sensing where a large pixel footprint implies the mixing matrix [A(x,t)] necessarily fill with diurnal and seasonal variations. Because the ground truth is difficult to be ascertained in the remote sensing, we have thus illustrated in this paper, each step of the LCNN algorithm for the simulated spatial-temporal varying BSS in speech, music audio mixing. We review and compare LCNN with other popular a-posteriori Maximum Entropy methodologies defined by ANN weight matrix-[W] sigmoid-(sigma) post processing H(Y=(sigma) ([W]X)) by Bell-Sejnowski, Amari and Oja (BSAO) called Independent Component Analysis (ICA). Both are mirror symmetric of the MaxEnt methodologies and work for a constant unknown mixing matrix [A], but the major difference is whether the ensemble average is taken at neighborhood pixel data X's in BASO or at the a priori sources S variables in LCNN that dictates which method works for spatial-temporal varying [A(x,t)] that would not allow the neighborhood pixel average. We expected the success of sharper de-mixing by the LCNN method in terms of a controlled ground truth experiment in the simulation of variant mixture of two music of similar Kurtosis (15 seconds composed of Saint-Saens Swan and Rachmaninov cello concerto).

  16. ESPAS: the European e-science platform to access near-Earth space data (Invited)

    NASA Astrophysics Data System (ADS)

    Belehaki, A.; Hapgood, M. A.; Ritschel, B.; Manola, N.

    2013-12-01

    Lebesis, Bruno Zolesi, Tatjana Gerzen, Ingemar Häggström, Anna Charisi, Ivan Galkin, Jurgen Watermann, Matthew Angling, Timo Asikainen, Alan Aylward, Henrike Barkmann, Peter Bergqvist, Andrew Bushell, Fabien Darrouzet, Dimitris Dialetis, Carl-Fredrik Enell, Daniel Heynderickx, Norbert Jakowski, Magnar Johnsen, Jean Lilensten, Ian McCrea, Kalevi Mursula, Bogdan Nicula, Michael Pezzopane, Viviane Pierrard, Bodo Reinisch, Bernd Ritschel, Luca Spogli, Iwona Stanislawska, Claudia Stolle, Eija Tanskanen, Ioanna Tsagouri, Esa Turunen, Thomas Ulich, Matthew Wild, Tim Yeoman

  17. The Prevalence, Risk Factors and Changes in Symptoms of Self Reported Asthma, Rhinitis and Eczema Among Pregnant Women in Ogbomoso, Nigeria

    PubMed Central

    Adeyemi, Adewale Samson; Adebayo, Philip Babatunde; Tanimowo, Moses O.; Ayodele, Olugbenga Edward

    2015-01-01

    Background Allergic disorders have become a major public health concern worldwide. No Nigerian study has examined the epidemiology of allergic diseases among women. Aim To document the prevalence, risk factors and the changes in the symptoms of allergic disorders during pregnancy. Settings and Design Cross-sectional study conducted at the booking and antenatal clinics of LAUTECH Teaching Hospital and Millennium Development Goals (MDG) Clinic of the Comprehensive Health Center, Oja Igbo, Ogbomoso, Nigeria. Materials and Methods Study enrolled 432 women from two public hospitals. Sociodemographic and clinical history were obtained and allergic disorders were diagnosed using ISAAC questionnaires. Results The prevalence of wheezing, eczema and rhinitis in pregnancy are 7.5%, 4.0% and 5.8% respectively. The prevalence of wheezing and eczema was slightly higher among the pregnant in past 12 months. Wheeze worsened in 70% (18/26), improved in 15% (2/26), and stable in 15% (2/26). Eczema worsened in 50% (7/14), improved in 7.1% (1/14) and stable in 42.9% (6/14), while allergic rhinitis worsened in 50% (11/22), improved in 22.7% (5/22) and stabilized in 27.3 % (6/22). In multivariate analysis, the risk of allergic diseases in pregnancy was increase 2 times by low income earning (CI: 1.2 – 2.1, p = 0.002), low level education (OR = 0.6, CI: 0.3 – 0.9, p = 0.011) and by family history of asthma, OR-4.3, CI – 1.3 – 13.9, p = 0.015. Family history of asthma increase the chances of asthma by 18.7 times, CI-2.3 – 152.2, p = 0.006, while the odd of eczema was increased 9.1 times (CI-2.7 – 30.6, p<0.001) and 2.4 times (CI: 1.2 – 4.7, p = 0.008) by second hand home smoking and low-family income respectively. The risk of allergic rhinitis were raised 1.8 times by low family income (CI 1.1 – 2.8, p = 0.013) and 3.9 times by family history of rhinitis (OR = 3.9, CI 1.2 – 12.7, p = 0.024). Conclusion Prevalence of wheezing and eczema are higher in pregnancy probably

  18. Characterizing Active Ingredients of eHealth Interventions Targeting Persons With Poorly Controlled Type 2 Diabetes Mellitus Using the Behavior Change Techniques Taxonomy: Scoping Review.

    PubMed

    Kebede, Mihiretu M; Liedtke, Tatjana P; Möllers, Tobias; Pischke, Claudia R

    2017-10-12

    explicit to avoid ambiguity. Response: Checked and avoided of a certain behavior Author: Please note that the journal discourages the use of parenthesis to denote either and/or and prefers to be explicit to avoid ambiguity. Response: Checked and avoided "and/or" and prefers to be explicit to avoid ambiguity. Response: Checked and avoided, and feedback on outcomes of behavior. Our results suggest that the majority of BCTs employed in interventions targeting persons with T2DM revolve around the promotion of self-regulatory behavior to manage the disease or to assist patients in performing health behaviors necessary to prevent further complications of the disease. Detailed reporting of the BCTs included in interventions targeting this population may facilitate the replication and further investigation of such interventions. ©Mihiretu M Kebede, Tatjana P Liedtke, Tobias Möllers, Claudia R Pischke. Originally published in the Journal of Medical Internet Research (http://www.jmir.org), 12.10.2017.

  19. Application of blind source separation to gamma ray spectra acquired by GRaND around Vesta

    NASA Astrophysics Data System (ADS)

    Mizzon, H.; Toplis, M. J.; Forni, O.; Prettyman, T. H.; Raymond, C. A.; Russell, C. T.

    2012-12-01

    of elements present in the spacecraft, of energy in the range 1 to 3.5 MeV. At energy >3.5 MeV, the dominant independent component highlighted by this method has no significant peaks, suggesting that it is not influenced by Vesta itself which is known to have a strong signal associated with iron at 7.6 MeV. Our method therefore represents a first step in retrieving the contribution of the spacecraft that could be used in conjunction with the mixing equation (1) to determine the contribution from the planet itself. 1 : Prettyman, T. H., Mcsween, Jr., H. Y., Feldman, W. C., JUN 2010. Dawn's GRaND to map the chemical composition of asteroids Vesta and Ceres. Geochimica and Cosmochimica Acta 74 (12, 1), A832, Con- ference on Goldschmidt 2010 - Earth, Energy, and the Environment, Knoxville, TN, JUN 13-18, 2010. 2 : Hyvarinen, A., Oja, E., May-Jun 2000. Independent component analysis: algorithms and applications. Neural Networks 13 (4-5), 411-430.

  20. Titanium (IV) sol-gel chemistry in varied gravity environments

    NASA Astrophysics Data System (ADS)

    Hales, Matthew; Martens, Wayde; Steinberg, Theodore

    . The test systems and experimental results obtained will be presented. 1. Okubo, T., Tsuchida, A., Okuda, T., Fujitsuna, K., Ishikawa, M., Morita, T., Tada, T. , Kinetic Analyses of Colloidal Crystallization in Microgravity -Aircraft Experiments. . Colloids and Surfaces A: Physicochemical and Engineering Aspects, 1999. 153: p. 515-524. 2. Okubo, T., Tsuchida, A., Kobayashi, K., Kuno, A., Morita, T., Fujishima, M., Kohno, Y., Kinetic Study of the Formation Reaction of Colloidal Silica Spheres in Microgravity Using Aircraft. Colloid Polymer Science, 1999. 277(5): p. 474-478. 3. Pienaar, C.L., Chiffoleau, G. J. A., Follens, L. R. A., Martens, J. A., Kirschhock, C. E. A., Steinberg, T. A., Effect of Gravity on the Gelation of Silica Sols. Chem. Mater., 2007. 19(4): p. 660-664. 4. Smith, D.D., et al., Effect of Microgravity on the Growth of Silica Nanostructures. Langmuir, 2000. 16(26): p. 10055-10060. 5. Zhang, X., Johnson, D.P., Manerbino, A.R., Moore, J.J., Schowengerdt, F. , Recent Mi-crogravity Results in the Synthesis of Porous Materials. AIP Conference Proceedings (Space Technology and Applications International Forum-1999, Pt. 1), 1999. 458: p. 88-93. 6. Dunbar, P.B., Bendzko, N.J.,, 1H and 13C NMR observation of the reaction of acetic acid with titanium isopropoxide. Materials Chemistry and Physics, 1999. 59: p. 26-35. 7. Krunks, M., Oja, I., T˜nsuaadu, K., Es-Souni, M., Gruselle, M., Niinistü,. L, Thermoanalytical study of acetylacetonate-modified titanium (iv) isopropoxide as precursor for TiO2 films. Journal of Thermal Analysis and Calorimetry, 2005: p. 483-488. 8. Moran, P.D., Bowmaker, G. A., Cooney, R. P., Vibrational Spectra and Molecular Associa-tion of Titanium Tetraisopropoxide. Inorg. Chem., 1998. 37(1): p. 2741-2748. 9. Somogyvari, A., Serpone, N.,, Evidence for five-coordination in titanium(1V) complexes. A nuclear magnetic resonance investigation. Canadian Journal of Chemistry, 1977. 56: p. 316-319.

  1. Recent progresses of neural network unsupervised learning: I. Independent component analyses generalizing PCA

    NASA Astrophysics Data System (ADS)

    Szu, Harold H.

    1999-03-01

    The early vision principle of redundancy reduction of 108 sensor excitations is understandable from computer vision viewpoint toward sparse edge maps. It is only recently derived using a truly unsupervised learning paradigm of artificial neural networks (ANN). In fact, the biological vision, Hubel- Wiesel edge maps, is reproduced seeking the underlying independent components analyses (ICA) among 102 image samples by maximizing the ANN output entropy (partial)H(V)/(partial)[W] equals (partial)[W]/(partial)t. When a pair of newborn eyes or ears meet the bustling and hustling world without supervision, they seek ICA by comparing 2 sensory measurements (x1(t), x2(t))T equalsV X(t). Assuming a linear and instantaneous mixture model of the external world X(t) equals [A] S(t), where both the mixing matrix ([A] equalsV [a1, a2] of ICA vectors and the source percentages (s1(t), s2(t))T equalsV S(t) are unknown, we seek the independent sources approximately equals [I] where the approximated sign indicates that higher order statistics (HOS) may not be trivial. Without a teacher, the ANN weight matrix [W] equalsV [w1, w2] adjusts the outputs V(t) equals tanh([W]X(t)) approximately equals [W]X(t) until no desired outputs except the (Gaussian) 'garbage' (neither YES '1' nor NO '-1' but at linear may-be range 'origin 0') defined by Gaussian covariance G equals [I] equals [W][A] Oja, Bell-Sejnowski, Amari-Cichocki, Cardoso), the LYAPONOV function L(v1,...,vn, w1,...wn,) equals E(v1,...,vn) - H(w1,...wn) is constructed as the HELMHOTZ free energy to prove both convergences of supervised energy E and unsupervised entropy H learning. Consequently, rather

  2. Preliminary observations of the SELENE Gamma Ray Spectrometer

    NASA Astrophysics Data System (ADS)

    Forni, O.; Diez, B.; Gasnault, O.; Munoz, B.; D'Uston, C.; Reedy, R. C.; Hasebe, N.

    2008-09-01

    model, the data variables are assumed to be linear mixtures of some unknown latent variables, and the mixing system is also unknown. The latent variables are assumed non- Gaussian and mutually independent and they are called the independent components of the observed data. These independent components, also called sources or factors, can be found by ICA. This is done by maximising a non-gaussianity criterion of the sources. As in [8], we have used the JADE algorithm developed and described in [9] for our analysis that we focused in the energy range from 750 to 3000 keV. We identify at least three meaningful components. The first one is correlated to the Thorium map (Fig. 4). The corresponding correlation coefficient spectrum exhibits the lines of Thorium, Potassium and Uranium (Fig. 5). The second component (Fig. 6) is clearly correlated with the Iron as shown on its corresponding spectrum (Fig. 5). A third component, identified at lower resolution, seems to be partly correlated with the altitude of the spacecraft (not shown). Further improvement in the data reduction, like corrections for altitude, cosmic ray, and neutron current variations should allow a better interpretation of the data. Acknowledgement. The SELENE GRS team members are: N. Hasebe, O. Okudaira, N. Yamashita, S. Kobayashi, Y. Karouji, M. Hareyama, S. Kodaira, S. Komatsu, K. Hayatsu, K. Iwabuchi, S. Nemoto, E. Shibamura, M.-N. Kobayashi, R.C. Reedy, K.J. Kim, C. d'Uston, S. Maurice, O. Gasnault, O. Forni, B. Diez. References. [1] Hasebe, N. et al. (2008) Earth, Planets and Space, 60, 299-312.. [2] Lawrence, D.J. et al. (1999) Geophys. Res. Lett., 26 (17), 2681-2684. [3] Evans, L.E. et al. (2006) J. Geophys. Res., 111, E03S04. [4] Prettyman, T.H. et al. (2006) J. Geophys. Res., 111, E12007. [5] Gillis, J.J. et al. (2004) Geo. et Cosmo. Acta, 68 (18), 3791-3805. [6] Comon P. (1994) Signal Processing, 36, 287-314. [7] Hyvärinen, A. and E. Oja (2000) Neural Networks, 13(4-5), 411-430. [8] Forni O. et al