733 research outputs found

    Nuevo registro de la biota ediacárica en la Arenisca de Jodhpur (Supergrupo de Marwar), Rajasthan occidental, India

    Get PDF
    In western Rajasthan, India, the Jodhpur Sandstone of the Marwar Supergroup has yielded a new Ediacaran fossil assemblage comprising macroscopic well-preserved specimens of Aspidella, Hiemalora, large Ediacaran discs, Tirasiana disciformis, Medusinites asteroides, Anfesta-like Ediacaran body fossils and microbial mat structures (Arumberia banksi, Kinneyia mat structures, wrinkle mat structures and other mat structures). The fossil record allows suggesting a broad correlation with the Fermuse Formation, Newfoundland, South Australia, White Sea of Russia and Norway, and regionally correlated with the Bhander Group of Vindhyan Supergroup and Krol Group of Lesser Himalaya.En el oeste de Rajasthan, India, la Arenisca de Jodhpur (Supergrupo de Marwar) ha librado un nuevo conjunto fósil ediacárico que comprende especímenes macroscópicos bien conservados de Aspidella, Hiemalora, grandes discos ediacáricos, Tirasiana disciformis, asteroides de Medusinites, fósiles de cuerpo blando ediacáricos similares a Anfesta y estructuras de tapices microbianas (Arumberia banksi, estructuras microbianas de tipo Kinneyia, estructuras microbianas arrugadas y otras estructuras microbianas). El registro fósil permite sugerir una amplia correlación con la Formación de Fermuse, Terranova, Australia meridional, el Mar Blanco de Rusia y Noruega, y la correlación regional con el Grupo de Bhander (Supergroup de Vindhyan) y el Grupo de Krol del Himalaya Interior

    Aspidella: un fósil de cuerpo blando ediacárico de la Arenisca de Jodhpur (Supergrupo de Marwar), área de Sursagar, Jodhpur, Rajasthan occidental, India

    Get PDF
    This paper describes well-preserved Aspidella remains, the Ediacaran body fossils from the Jodhpur Sandstone of the Marwar Supergroup in Sursagar area, Jodhpur, western Rajasthan, India. They show distinct morphological features previously described in other famous Ediacaran fossil sites, such as the Fermuse Formation of Newfoundland, South Australia and White Sea of RussiaSe describen en este trabajo los restos bien conservados de Aspidella, fósiles de cuerpo blando ediacáricos de la Arenisca de Jodhpur (Supergrupo de Marwar) el área de Sursagar, Jodhpur, al oeste de Rajasthan, India. Éstos muestran características morfológicas características descritas anteriormente en otros famosos yacimientos fósiles ediacáricos, como los de la Formación de Fermuse (Terranova), Australia meridional y el Mar Blanco de Rusia

    Surface modification of silicate, borosilicate and phosphate bioactive glasses to improve/control protein adsorption: PART I

    Get PDF
    Bioactive glasses (BGs) are promising for bone tissue regeneration. BG composition can be tailored, according to the application of interest, and/or functionalized with organic molecules/biomolecules to improve their performances. However, despite the wide knowledge concerning BGs, their interaction with proteins, fundamental for controlling the fate of the implant, has not been deeply investigated yet. Controlling or predicting protein adsorption requires a full understanding of the materials surface physico-chemical properties. In this work, four different BGs (S53P4, B25, SCNB, PhGlass) were surface-modified by four different treatments: 72 h-soaking in TRIS, 72 h soaking in simulated body fluid, APTES grafting and quaternized APTES grafting. The surfaces were then characterized both untreated and after each treatment by contact angle, zeta potential analysis, X-ray photoelectron spectroscopy, Fourier Transform InfraRed–Attenuated Total Reflectance spectroscopy and Scanning Electron Microscopy and Energy Dispersive Spectroscopy. Inductively Coupled Plasma – Optical Emission Spectrometry was then performed to investigate the ion leaching. The aim of this study (Part I) is the physico-chemical characterization of BGs as a function of the implemented treatments, aiming to better understand how the superficial properties are successively affecting protein adsorption. Protein adsorption on untreated and treated BGs will be discussed in a following manuscript (Part II)

    Thermal Time Scales in a Color Glass Condensate

    Full text link
    In a model of relativistic heavy ion collisions wherein the unconfined quark-gluon plasma is condensed into glass, we derive the Vogel-Fulcher-Tammann cooling law. This law is well known to hold true in condensed matter glasses. The high energy plasma is initially created in a very hot negative temperature state and cools down to the Hagedorn glass temperature at an ever decreasing rate. The cooling rate is largely determined by the QCD string tension derived from hadronic Regge trajectories. The ultimately slow relaxation time is a defining characteristic of a color glass condensate.Comment: 5 pages, ReVTeX format, nofigure

    A Review and an Approach of Flying Electric Generators as Alternate Source of Energy

    Full text link
    This paper presents a review of flying electric generators which are used to harness kinetic energy in powerful, persistent high altitude winds. It has been found that FEGs could give individual output of up to 40MW. It is a lighter wind turbine that rotates about a horizontal axis in response to wind, generating electrical energy. This electrical energy is transferred down for immediate use, or to a set of batteries for later use, or to the power grid. This paper presents the critical analysis of existing literature which is relevant to flying electric generator Though, the literature consists of a lot many research contributions, but, here, we have analyzed some important research and review papers. The existing approaches are categorized based on the basic concepts involved in the mechanisms. The emphasis is on the concepts used by the concerned authors, the database used for experimentations and the performance evaluation parameters. Their claims are also highlighted. Finally, the findings are summarized related to the studied and analyzed research papers. Paper concludes with the motivation behind identified problem

    A Review and an Approach of Water Pollution Indication using Arduino Uno

    Full text link
    Drinking water is critical for the wellbeing and prosperity of all people and creatures because water play major role in all living beings and most danger disease are caused by water and it is our duty to provide clean and safe water and also to monitor the pollution level in water it is additionally essential for farming utilization for good product yielding and natural way of life linkage wellbeing issues. With over 200 children dying per day due to unsafe water, drinking water crisis is ranked one on the global risk by World Economic Forum, 2015. This paper presents an easy and comprehensive methodology is microcontroller sensor based system continuous observing and pollution recognition for both drinking and non-drinking water dissemination frameworks and in addition for customer locales

    Automatic Overhead Water Tank Cleaning System: A Review and an Approach

    Full text link
    Aim of this paper is to develop a mechanical system for cleaning domestic cylindrical water tank. The mechanical system includes two main mechanisms which are rack and pinion gear mechanism and reciprocating four bar linkage mechanism. The rack and pinion arrangement is used to move whole mechanical system up and down for cleaning the cylindrical tank. The rack is fixed on the motor and the four-bar mechanism is attached to the motor shaft. PVC brushes are attached to the ends of the four-bar linkage. Four bar linkage is made in such a way that it can be adjusted according to inside diameter of the tank. When the motor is started the linkage rotates and with the help of brushes, cleaning of wall and base of tank takes place. The purpose of this project is to reduce the human efforts and to avoid the chemical influence on health of person entering the tank for cleaning. In this modern world, cleaning of overhead tanks manually is a tedious job. To overcome this we have aimed at tackling the disadvantages of cleaning overhead tanks, so an automatic system overhead tank cleaning is designed to provide high safety, high efficiency, less time for cleaning and to avoid environmental pollution problems. Purpose of this paper is to clean domestic cylindrical water tank with the help of mechatronics system. The mechatronics system consists of a grooved gear rod attached to two arms with brushes at ends. The two arms are connected to the gear rod by nut. By rotating the gear rod, the up and down motion of the two arms is achieved. The gear rod is rotated with the help of a D.C gear motor. The main grooved shaft is powered by an A.C motor. The motor and the shaft are connected by a rubber belt. The clockwise rotation of the main shaft will make the arms move and vice versa. The whole operation is controlled by a circuit consisting of relay switches, buttons, and PIC microcontroller. The number of times for the operation to repeat can be fed into the circuit. The achievement of this project is reduction of cost and manual labour because there will be harmful diseases for the person who will go inside and it will affect the health as well as the other human being who consumes water from the tank

    Optical observations of the bright long duration peculiar GRB 021004 afterglow

    Full text link
    The CCD magnitudes in Johnson B,VB,V and Cousins RR and II photometric passbands are determined for the bright long duration GRB 021004 afterglow from 2002 October 4 to 16 starting \sim 3 hours after the γ\gamma-ray burst. Light curves of the afterglow emission in BB,VV,RR and II passbands are obtained by combining these measurements with other published data. The earliest optical emission appears to originate in a revese shock. Flux decay of the afterglow shows a very uncommon variation relative to other well-observed GRBs. Rapid light variations, especially during early times (Δt<2\Delta t < 2 days) is superposed on an underlying broken power law decay typical of a jetted afterglow. The flux decay constants at early and late times derived from least square fits to the light curve are 0.99±0.050.99\pm0.05 and 2.0±0.22.0\pm0.2 respectively, with a jet break at around 7 day. Comparison with a standard fireball model indicates a total extinction of E(BV)=0.20E(B-V)=0.20 mag in the direction of the burst. Our low-resolution spectra corrected for this extinction provide a spectral slope β=0.6±0.02\beta = 0.6\pm0.02. This value and the flux decay constants agree well with the electron energy index p2.27p\sim 2.27 used in the model. The derived jet opening angle of about 77^{\circ} implies a total emitted gamma-ray energy Eγ=3.5×1050E_{\gamma} = 3.5\times10^{50} erg at a cosmological distance of about 20 Gpc. Multiwavelength observations indicate association of this GRB with a star forming region, supporting the case for collapsar origin of long duration GRBs.Comment: 19 pages, 3 figures, BASI, 31, 1

    An unusual very low-mass high-amplitude pre-main sequence periodic variable

    Full text link
    We have investigated the nature of the variability of CHS7797, an unusual periodic variable in the Orion Nebula Cluster. An extensive I-band photometric data set of CHS7797 was compiled between 2004-2010 using various telescopes. Further optical data have been collected in R and z' bands. In addition, simultaneous observations of the ONC region including CHS7797 were performed in the I, J, Ks and IRAC [3.6] and [4.5] bands over a time interval of about 40d. CHS7797 shows an unusual large-amplitude variation of about 1.7 mag in the R, I, and z' bands with a period 17.786. The amplitude of the brightness modulation decreases only slightly at longer wavelengths. The star is faint during 2/3 of the period and the shape of the phased light-curves for seven different observing seasons shows minor changes and small-amplitude variations. Interestingly, there are no significant colour-flux correlations for wavelengths smaller than 2microns, while the object becomes redder when fainter at longer wavelengths. CHS7797 has a spectral type of M6 and an estimated mass between 0.04-0.1Msun. The analysis of the data suggests that the periodic variability of CHS7797 is most probably caused by an orbital motion. Variability as a result of rotational brightness modulation by spots is excluded by the lack of any color-brightness correlation in the optical. The latter indicates that CHS7797 is most probably occulted by circumstellar matter in which grains have grown from typical 0.1 microns to 1-2 micron sizes. We discuss two possible scenarios in which CHS7797 is periodically eclipsed by structures in a disc, namely that CHS7797 is a single object with a circumstellar disc, or that CHS7797 is a binary system, similar to KH15D, in which an inclined circumbinary disc is responsible of the variability. Possible reasons for the typical 0.3mag variations in I-band at a given phase are discussed.Comment: 11 pages, 9 figures, accepted for publication A&
    corecore