bluuebunny/crossref_metadata_2025 huggingface dataset:
Supersoft Sources
Authors: Kahabka P.
Published: March 2016

Supersoft X-ray sources are a new class of luminous X-ray binaries discovered with the X-ray telescopes of the Einstein and ROSAT satellites and extensively studied in the optical with ground based telescopes, in the UV with IUE and HST and in X-rays with ROSAT, Beppo-SAX and ASCA (cf. Kahabka & van den Heuvel 1997, van Teeseling 1997). The luminosities derived for a first sample of supersoft sources studied with moderate resolution X-ray spectroscopy (using Beppo-SAX LECS and ASCA SIS detectors, Parmar et al. 1997, Ebisawa et al. 1997) have been predicted to follow Iben’s stability line (Iben 1982), i.e. the location in the Hertzsprung-Russell diagram which separates the plateau phase from the cooling phase. This is not unreasonable as any system experiencing steady-state accretion, i.e. accretion at a rate equalling about the nuclear burning rate will be found close to the stability line. If the accretion rate exceeds this limit then the white dwarf gets bloated and disappears in X-rays. If the accretion rate falls below this limit the white dwarf envelope cools, the luminosity as well as the temperature ceases and the source enters unstable recurrent nuclear burning. From the population synthesis calculations of Yungelson (1996) follows that there exit for the Milky Way a few sources at any epoch which are more massive than 1.2 MQ. They are expected to be extremely X-ray bright and may be standard candles (cf. Table 1 and Figure 1 for the brightest known supersoft sources per galaxy Milky Way to NGC 55). Their spectral distribution is expected to be similar to that of the extremely hot galactic source RXJ0925.7-4758 (it peaks at 1 keV and the flux is distributed from 0.5 to 2 keV, see Figure 2 for the ASCA spectrum of RX J0925.7-4758 (and CAL 87) as derived by Ebisawa et al. 1997).
Heating of Chromospheres and Coronae
Authors: Ulmschneider P.
Published: March 2016

Almost all nondegenerate stars have chromospheres and coronae. These hot outer layers are produced by mechanical heating. The heating mechanisms of chromospheres and coronae, classified as hydrodynamic and magnetic mechanisms, are reviewed here. Both types of mechanisms can be further subdivided on basis of the fluctuation frequency into acoustic and pulsational waves for hydrodynamic and into AC- and DC-mechanisms for magnetic heating. Intense heating is usually associated with the formation of very small spatial scales, which are difficult to observe. Yet, global stellar observations, because of the dependence of the mechanical energy generation on the basic stellar parameters (Teff, gravity, rotation, metallicity) can be extremely important to identify the dominant heating mechanisms.
Acceleration of the Solar Wind: A New View
Authors: Hansteen V.H. , Leer E.
Published: March 2016

The last few years have seen the development of solar wind models characterized by high coronal proton temperatures, low electron temperatures and low densities in the inner corona. In addition the emphasis on “additional” acceleration via Alfvén waves has been muted and been replaced by models where the acceleration is essentially complete within 1OR0. This work has, in part, been spurred by Ulysses observations of the high speed wind and by the expectations of the observations to be made by the various instruments on the SOHO satellite. In this paper we show how these new models differ from earlier ones.
Modern Astronomical Developments in India
Authors: Kochhar Rajesh
Published: March 2016

Modern astronomy came to India in tow with the Europeans and was institutionalized more than 200 years ago by the (English) East India Company with the establishment in 1790 of Madras Observatory for assistance in navigational and geographical surveys. One hundred years later, in 1899, it was replaced by a solar observatory at Kodaikanal set up by the government to meet the European scientists’ demand for sunny skies and in the hope that a study of the Sun would help predict the failure of monsoons, the key factor then as now in Indian economy. It is mildly interesting to note that, when the scientific agenda was laid down by the Royal Society, no mention was made of climate or rains [1].
Astronomy in the Former Soviet Union
Authors: Bochkarev Nikolai G.
Published: March 2016

The Soviet Union developed science (including astronomy) to a high level, although largely isolated from the rest of the world. In 1990 about 2% of GDP, i.e. tenths of a billion dollars per year, were invested in science. The USSR occupied fourth place in the world in respect of its investment in science. More than a million persons worked in scientific research, with about 3,000 of those in astronomy.
How Does the United Nations Contribute to the Worldwide Development of Astronomy?
Authors: Haubold H.J.
Published: March 2016

Of the 185 countries that are Member States of the United Nations, nearly 100 have professional or amateur astronomical organizations. Only about 60 of these countries, however, are sufficiently involved in astronomy to belong to the International Astronomical Union. Only about 20 countries, representing 15% of the world’s population, have access to the full range of astronomical facilities and information.
Training in Astronomy
Authors: Gerbaldi M.
Published: March 2016

Astronomy offers a unique opportunity for promoting the science teaching in its present crisis. Astronomy can be introduced at various levels and become the medium by which both primary science education and public understanding of science are stimulated.

At the University level, astronomy can be introduced in the curricula of university colleges and be a subject for M.Sc. and Ph.D. degrees. Astronomy, can give students the opportunity to work scientifically from observations and known physical laws in order to derive knowledge in another field of science. Astronomy can be taught with less formalism and more experimentation, giving students a feel for the link between a phenomenon and its theoretical representation, and how and why a given observation can be represented by different theoretical models.
Popularization as an Aid for Formal Education
Authors: Fierro Julieta
Published: March 2016

In the following article we present the way in which professional astronomers are trying to influence the general understanding of astronomy in Mexico. The long-term goal is to have a population that includes science as part of its culture. The paper is mainly a list of some of the many things that can be done to enhance understanding of science, descriptions of the different items can be found in the references, which include the proceedings of three meetings on astronomy education and magazines dedicated to the teaching of astronomy.
What can We do from Japan?
Authors: Kodaira Keiichi
Published: March 2016

Although the importance of astronomy as a field of basic science and a discipline of fundamental education is well recognized among us, it is not always easy to share this recognition with those people whose interests are tightly bound to their daily lives on the Earth, even within one country. The activities of the Japanese within the “Neighborhood Program” are reviewed and brief discussions of them are presented.
Access to Journals
Authors: Abt Helmut A.
Published: March 2016

We want to help scientists in developing countries (DC) do research because of their intelligence and devotion to science. But frankly, observational and even theoretical research is very expensive. For a developed country an estimate of the average project cost that includes salaries, the equipment used, and the institutional overhead is roughly $100,000 (US). In DC the salaries are lower, but not necessarily the equipment.
OH Megamaser Pumping Models
Authors: Kylafis N. D. , Pavlakis K. G.
Published: March 2016

We would like to review the current status of OH megamaser pumping models. Contrary to the quantity and quality of observations of OH megamasers, surprisingly little theoretical modeling has been done on them so far.
Properties of OH Megamaser Galaxies
Authors: Kandalyan Rafik
Published: March 2016

An analysis of a sample of OH megamaser galaxies is presented. It is shown that the dependence of OH luminosity on FIR (far infrared) luminosity is not quadratic, as previously assumed, but closer to linear. Using a luminosity function of the luminous infrared galaxies, as well as linear relationship between OH and FIR luminosities the expected number of OH megamaser galaxies has been estimated. Spectral energy distributions (SED) of 16 megamaser galaxies have been constructed using multiwavelength (from radio to X-ray) data. The SED of megamasers look closely similar from radio to X-ray. It is shown that the maser amplification coefficient depends both on the OH main line to 60 micron ratio and the main line to 2.2 micron ratio. The OH main lines ratio (f1667/f1665) decreases, while the flux density at 10 micron is increasing.
H2O Megamasers and Black Holes
Authors: Moran J. M.
Published: March 2016

Twenty-one H2O masers have been identified in the nuclei of active galaxies. The detection rate is about 7 percent. Very Long Baseline Interferometric data of four of these maser systems (NGC 4258, NGC 1068, NGC 4945, and NGC 3079) show evidence of Keplerian disks on a subparsec scale. The best example is NGC 4258. There the masers trace a thin warped disk in nearly perfect circular Keplerian motion. If the apparent thinness is indicative of hydrostatic equilibrium, then the kinetic temperature must be less than 1000K, the magnetic field less than 200 mG, and the mass accretion rate less than about α10-3 M⊙/yr, where a is the viscosity parameter. From direct Zeeman measurements the toroidal magnetic field strength is less than 300 mG. The proper motions of the systemic maser feature imply a distance to the galaxy of 7.3 ± 0.3 Mpc. The high-velocity features show no detectable proper motions or accelerations, which confirms the model of circular Keplerian motion, and puts severe constraints on any alternative model. A feature in the systemic group flared to 20 Jy, offering opportunities to study the physics of the maser emission.
Pumping of H2O Megamasers
Authors: Elitzur Moshe
Published: March 2016

Strong H2O maser emission is detected from active galactic nuclei (AGN) as well as Galactic objects such as star-forming regions and late-type stars. In spite of the widely different luminosities of the different masers, a common pump mechanism seems adequate: neutral collisions at densities of ˜ 108-1010 cm-3 and temperatures of ˜ 250-500 K. The different properties of the various masers can be attributed to geometry. Although disk rotation controls the AGN maser geometry it does not directly determine the dimensions. X-ray radiation and spiral shocks have been suggested as the heating sources of H2O megamasers. Both are capable of explaining the observations, and the radiative scenario seems best understood in terms of chance alignment of standard broad-line-region clouds. It is not yet clear whether these different proposals produce distinct maser signatures.
Variability of Interstellar Water Vapor Masers
Authors: Mendoza-Torres J.E. , Lekht E.E.
Published: March 2016

We present some results of observations of H2O masers (1.35 cm line) in Star-Forming Regions. The observations have been made from the beginning of the eighties at the 22 m radiotelescope at Pushchino, Russia (Lekht et al. 1995). The time interval between two consecutive observations is about one month. The spectral resolution is 0.1 km/sec and the sensitivity, for a time integration of 15 minutes, is about 10 Jy. The sources with which we deal in this work are: ONI, ON2, W31A, W75S, S128 and S252A. We pay attention to results of flux variations that are either common to all the sources or are results that allow to establish differences between them.
Global VLBA Observations of NGC 3079
Authors: Satoh Satoko , Inoue M. , Nakai N. , Shibata K.M. , Kameno S. , Migenes V. , Diamond P. J.
Published: March 2016

NGC 3079 has very luminous water megamaser from the nucleus, the peak of the spectrum being blueshifted by 180 km s-1 from the systemic velocity of the galaxy (Vsys = 1131 km s-1) (Henkel et al. 1984, Haschick & Baan 1985). Core-jet like continuum structure is also found in the nuclear region (Irwin & Seaquist 1988). No velocity drift for main features of water maser (VLSR — 941-975 km s1) has been shown (Nakai et al. 1995). However, the drift was recently detected for the maser of 1190 km s-1 (Nakai 1997). HI and OH absorptions were detected in the nucleus (Haschick & Baan 1985, Irwin & Seaquist 1991). Thus this galaxy is very unique object to investigate water masers, continuum structure and absorption features all together with VLBI.
VLBI from the Moon
Authors: Gurvits L. I.
Published: March 2016

Very Long Baseline Interferometry (VLBI) technique occupies a special place among tools for studying the Universe due to its record high angular resolution. The latter is in the inverse proportion to the length of interferometer baseline at any given wavelength. Until recently, the available angular resolution in radio domain of about 1 milliarcsecond at centimeter wavelengths was limited by the diameter of the Earth. However, many astrophysical problems require a higher angular resolution. The only way to achieve this at a given wavelength is to create an interferometer with the baseline larger than the Earth’s diameter by placing at least one telescope in space. In February 1997, the first dedicated Space VLBI mission, VLBI Space Observatory Program (VSOP), led by the Institute of Space and Astronautical Sciences (Japan) has been launched (Hirabayashi 1997). The VSOP mission opens a new dimension in the development of radio astronomy of extremely high angular resolution and will be followed by other Space VLBI missions. A review of scientific drives and technological challenges of the next generation Space VLBI mission have been discussed, for example, by Gurvits et al. (1996) and Ulvestad et al. (1997).
Advanced Technology Lunar Astronomy Mission, the Moon as an Immense Optical Bench in Vacuum
Authors: Chen Peter C. , Kondo Yoji , Oliversen Ronald J.
Published: March 2016

The Moon combines some of the most attractive features for astronomical observations from space (no atmospheric absorption, perfect seeing, etc.) and those from ground (large steady optical bench, ease of control from Earth, etc.). Astronomers have planned for telescopes on the Moon for decades but, due to its primary obstacle – high cost – they have not yet been built, save one small telescope that was carried to the Moon on an Apollo mission.
The Leonids and the Comet:- History and Theory
Authors: Williams I.P.
Published: March 2016

The recorded history of the appearances of spectacular Leonid displays have been discussed for example in Yeomans (1981) and also in other papers at this meeting. The similarity in the orbits and that of comet 55P/Tempel-Tuttle is a strong indication that they are related. Further proof of this comes from the fact that the most spectacular displays associated with this stream are seen at time intervals that are multiples of the orbital period of the comet. The explanation for the occurrence of storms is thus that a well populated group of meteoroids are located close to the parent comet. Such a grouping of meteoroids would be formed if the comet were still active, not an unreasonable assumption. However, this raises an other question, namely why have the older of these meteoroids ejected perhaps several thousand years ago, not spread about the orbit. Standard models (eg Williams 1992) suggest that in 20 or so orbits meteoroids will have spread all the way from being close to the comet to being at the opposite point of the orbit. Hence, meteors in similar numbers should be seen every November coming from the Leonid stream. This is not the case, the average zenithal hourly rate of meteors in non-storm years being less than 10 as opposed to several thousand during a storm.
Recent Visual Observations of the Leonid Meteor Shower
Authors: Brown P.
Published: March 2016

We know the Leonid shower primarily from its record of visual appearances over the last millenium. The period of the stream and its status as a cosmic phenomenon are all intimately linked to historical visual observations of the stream. The advent of modern observational techniques in meteor astronomy such as radar and photography has not decreased the value of visual recordings of the stream; on the contrary, visual observations form our primary means of long-term monitoring of the shower.
Observations of the Leonids in Central Asia
Authors: Babadzhanov P.B.
Published: March 2016

Observations in Central Asia in 1965-1966 by both photographic and radar methods allowed a determination of the radiants and orbits of Leonids (Babadzhanov and Getman 1970). Photographs showed that meteoroids undergo quasi-continuous fragmentation (QCF) in the Earth’s atmosphere. Taking account of QCF, the density of the Leonid meteoroids were found to lie between 1 and Agcm-3 the average being 2gcm-3 (Babadzhanov 1994), in agreement with the density range of between 0.2 and 6gcm-3 given by Maas et al (1990) for dust grains from comet P/1 Halley, with values below 0.6 being rare. Further, the icy grains have a density of about 1gcm-3 while silicate grains have a mean density 2.5 times higher.
The Three Galileos Conference: An Overview of the Event
Authors: Barbieri C.
Published: March 2016

A conference having the title The Three Galileos: the Man, the Spacecraft, the Telescope, was held at the University of Padova from 7-10 January 1997. The conference was jointly organized by the U.S. space agency NASA, JPL, the German space agency DARA, the University and Astronomical Observatory of Padova, and the Telescopio Nazionale Galileo, with the added support of the International Astronomical Union. The scientific committee was composed of: C. Barbieri (Chairman, University of Padova), S. Atreya (University of Michigan), E. Bellone (University of Padova), M. Belton (NOAO), P. Benvenuti (ESA), F. Bertola (University of Padova), M. Calvani (Astronomical Observatory of Padova), G. Cariolaro (University of Padova), W. Ip (Max-Planck-Institute for Aeronomy), T. Johnson (JPL), T. Owen (University of Hawaii), J. Rahe (NASA), and R. West (ESO). The purpose was to discuss the discovery of the Medicean Moons by Galileo Galilei in Padova from 7-15 January 1610, the results of the Galileo spacecraft during the cruise phase and while orbiting the Jovian system, and the construction of the 3.5-m active-optics Italian telescope Galileo (TNG) in the Canary Islands.
The Infrared Space Observatory (ISO): Overview and Status
Authors: Kessler M.F.
Published: March 2016

The Infrared Space Observatory (ISO) is a cryogenically-cooled satellite giving the astronomical community, for the first time, the capability of making detailed observations at infrared wavelengths (2.5-240 ˜m) with a sophisticated and sensitive set of observatory-class instruments for a period in excess of two years.

The proposal for ISO was made to ESA in 1979 and it was selected in 1983 to be the next new start. The instruments were chosen in 1985 and ISO’s main industrial development started in 1988. Launch took place in November 1995 and the helium coolant is expected to last until April 1998. The calibration and data analysis will be improved during the post-operations phase, which is funded to the end of 2001.
Observations with Isophot
Authors: Lemke D.
Published: March 2016

While all channels of the instrument (Lemke et al. 1996) are fully operational in the 21st month of the mission, some have turned out to be particularly productive: (1) far infrared mapping in the 200 /im range and (2) spectrophotometry in the middle infrared. The detection sensitivity of these modes is close to the preflight expectation. The photometric calibration of the instrument is a demanding task. Transient and memory effects of the low background detectors, responsivity drifts and spikes caused by the cosmic radiation as well as nonlinearities due to the preamps and the complex optical subsystems require corrections. Fortunately almost all of these effects are reproducable and correction algorithms are under development. While spectrophotometric (Klaas et al. 1997) and staring observations are already calibrated to better than ±20..30% in the pipeline data products, similar values will be achieved for all observing modes in the near future.
The Interstellar Dust Emission Seen by ISO
Authors: Puget J.L.
Published: March 2016

Among the important contributions of ISO to the physics of the interstellar medium, this paper concentrates only on the emission from the solid phase (the interstellar grains) and the small atom clusters which are the bridge between the grains and the small molecules with less than about 10 atoms.
Molecular Spectroscopy with ISO
Authors: Puget J.L.
Published: March 2016

Among the important contributions of ISO to the physics of the interstellar medium, this paper concentrates only on the emission from the solid phase (the interstellar grains) and the small atom clusters which are the bridge between the grains and the small molecules with less than about 10 atoms.
Observations of Supernova Remnants With ISO
Authors: Tuffs R.J.
Published: March 2016

Pointed observations with ISO have been made, or are planned, towards 58 supernova remnants (SNRs) in the galaxy and Magellanic clouds. The main emphasis is on detailed studies of gas, dust and synchrotron emission from selected regions within 24 well studied galactic remants. First results are available for Cas A (Lagage et al. 1996, 1997; Tuffs et al. 1997; Unger et al. 1997), the Cygnus Loop (deCourchelle et al 1997; Fischera et al. 1997), RCW103 (Oliva et al. 1997; Wright et al. 1997), and W44 and 3C391 (Reach and Rho 1996). These are providing insights into issues such as the yield and composition of condensates in supernova ejecta, the processing of grains by adiabatic and radiative shocks, and the measurement of cold gas, inaccessible to optical observations, both from cool regions in radiative shocks and from unshocked ejecta. In this progress report these points are illustrated with reference to Cas A, the prototype of an ejecta-dominated remnant of a massive core-collapse supernova, and the Cygnus Loop and RCW103 as prime examples of radiative shocks delineating the interaction of fast blast waves with diffuse atomic and dense molecular clouds, respectively.
Comets
Authors: Keller H.U.
Published: March 2016

Comets, the most pristine members of our solar system, are faint at large heliocentric distances (rh > 3 au) and therefore difficult to observe. Data reduction of these faint objects (periodic comets) is time consuming and hence most often just preliminary results can be discussed. Only the orbits of short periodic comets can be predicted and most of those that have been accessible for ISO have been covered within the guaranteed time programme. About 10 proposals were accepted by the selection for open time proposals. A target of opportunity team was formed. The outstanding comet Hale-Bopp (C/1995 01), one of the brightest and therefore most active comets of this century, was suggested and accepted as TOO. The important results from the ISO cometary programme are derived from its observations. In addition to the observations of "classic" comets the newly detected (Jewitt and Luu, 1993) transneptunian objects, probably objects from the Kuiper belt, are observed in an attempt to determine their physical properties.
Lay Brothers: The Other Men in the Mendicant Orders of New Spain-ERRATUM
Authors: Lavrin Asunción
Published: March 2016

The original publication of this article contained an incorrect email address for the author. The correct address is reproduced below.

The publisher regrets the error.
“If they remained as mere words”: Trent, Marriage, and Freedom in the Viceroyalty of Peru, Sixteenth to Eighteenth Centuries
Authors: Latasa Pilar
Published: March 2016

The right of persons to marry without coercion and live their marriage freely was one of the foremost and frequently mentioned topics among synod and council fathers, moralists, and canon lawyers in colonial Spanish America. Within the territory of the viceroyalty of Peru, the recommendations of the Council of Trent in this regard took the form of a new set of ecclesiastical regulations, derived from synods and councils that occurred from the sixteenth through the eighteenth century.
Columbus and the Quest for Jerusalem: How Religion Drove the Voyages that Led to America. By Carol Delaney. New York: Free Press, 2011. Pp. 319. Illustrations. Appendix. Bibliography. Index. $16 paper.
Authors: Schwaller John F.
Published: March 2016

Carole Delaney has written a very approachable and highly readable book about Columbus for the general public, choosing to deal most thoroughly with his millenarian beliefs, ties to the Franciscan order, and the religious ideas behind his voyages. The book draws on published materials, many of them primary sources, but introduces no new archival findings. Delaney manages the sources well. The Times Literary Supplement hailed her work as one of the 100 best books of 2011.
Simuliertes Glücksspiel
Authors: Meyer Gerhard , Brosowski Tim , Meduna Marc von , Hayer Tobias
Published: March 2016

Zusammenfassung. In internetbasierten sozialen Netzwerken, in Form von Demoversionen kommerzieller Spielangebote sowie Computer- und Videospielen erfreuen sich simulierte Glücksspiele, die aufgrund fehlender Geldeinsätze die formal-juristischen Kriterien für ein Glücksspiel nicht erfüllen und damit bspw. keinen Altersrestriktionen unterliegen, wachsender Beliebtheit. Ziel des Beitrages ist es, die mutmaßlichen gesundheitsrelevanten Gefährdungspotenziale dieser Spielformen durch eine Literaturrecherche aufzuzeigen, den aktuellen Kenntnisstand anhand der vorliegenden empirischen Befunde systematisch zusammenzufassen sowie mögliche Forschungslücken zu identifizieren. Die Datenbanken PubMed/MEDLINE, PsycInfo und Web of Science wurden anhand relevanter Schlagwörter nach peer-reviewten, empirischen Beiträgen durchsucht und um Dissertationen und Marktanalysen ergänzt. Insgesamt sind 56 Fundstellen in die Analyse eingeflossen. Querschnittbefragungen aus verschiedenen Ländern bestätigen die Attraktivität der Angebote, insbesondere für Kinder und Jugendliche. Während spielimmanente Faktoren wie gesteuerte Spielausgänge offenbar die Spiellust und kognitive Verzerrungsmuster fördern, bestätigt eine erste Längsschnittstudie den prädiktiven Wert von Mikrotransaktionen für den Umstieg von simuliertem zu klassischem Glücksspiel. Derartige Migrationsprozesse werden durch gezielte Werbung noch verstärkt. Ob von der Einbindung sozialer Komponenten risikoerhöhende Effekte ausgehen, muss zum gegenwärtigen Zeitpunkt offen bleiben. Weitere Befunde liegen zu Teilnahmemotiven, Konsummustern, Komorbiditäten und potentiellen Positiveffekten vor. Die Erhebung empirischer Daten zu psychosozialen Auswirkungen simulierter Glücksspiele stellt eine wichtige Aufgabe zukünftiger Forschung dar, um wissenschaftlich abgesicherte Forderungen zu notwendigen Präventions- und Regulierungsmaßnahmen dieser Angebote aufstellen zu können.
The Moderating Impact of Distal Regularities on the Effect of	Stimulus Pairings
Authors: Hughes Sean , De Houwer Jan , Barnes-Holmes Dermot
Published: March 2016

Abstract. Throughout much of the past century psychologists have focused their attention on a seemingly simple question: How do people come to like or dislike stimuli in the environment? Evaluative Conditioning (EC) – a change in liking due to the pairing of stimuli – has been offered as one avenue through which novel preferences may be formed and existing ones altered. In the current article, we offer a new look at EC from the perspective of Contextual Behavioral Science (CBS) and, more specifically, Relational Frame Theory (RFT). We briefly review the EC literature, introduce Contextual Behavioral Science (CBS), Relational Frame Theory (RFT), and then describe a behavioral phenomenon known as arbitrarily applicable relational responding (AARR). Afterwards, we examine the relationship between EC and AARR. This novel perspective offers ways to organize existing as well as predict new EC effects, contributes to debates on “genuine” EC, human versus nonhuman EC, and further facilitates the development and refinement of cognitive theories of EC.
Pneumococcal Pneumolysin Induces DNA Damage and Cell Cycle Arrest
Authors: Rai Prashant , He Fang , Kwang Jimmy , Engelward Bevin P. , Chow Vincent T.K.
Published: March 2016

Streptococcus pneumoniae produces pneumolysin toxin as a key virulence factor against host cells. Pneumolysin is a cholesterol-dependent cytolysin (CDC) toxin that forms lytic pores in host membranes and mediates pneumococcal disease pathogenesis by modulating inflammatory responses. Here, we show that pneumolysin, which is released during bacterial lysis, induces DNA double strand breaks (DSBs), as indicated by ataxia telangiectasia mutated (ATM)-mediated H2AX phosphorylation (γH2AX). Pneumolysin-induced γH2AX foci recruit mediator of DNA damage checkpoint 1 (MDC1) and p53 binding protein 1 (53BP1), to sites of DSBs. Importantly, results show that toxin-induced DNA damage precedes cell cycle arrest and causes apoptosis when DNA-dependent protein kinase (DNA-PK)-mediated non-homologous end joining is inhibited. Further, we observe that cells that were undergoing DNA replication harbored DSBs in greater frequency during pneumolysin treatment. This observation raises the possibility that DSBs might be arising as a result of replication fork breakdown. Additionally, neutralizing the oligomerization domain of pneumolysin with monoclonal antibody suppresses DNA damage and also cell cycle arrest, indicating that pneumolysin oligomerization is important for causing DNA damage. Taken together, this study reveals a previously unidentified ability of pneumolysin to induce cytotoxicity via DNA damage, with implications in the pathophysiology of S. pneumoniae infection.
Influence of humidity on the initial emittable concentration of formaldehyde and hexaldehyde in building materials: experimental observation and correlation
Authors: Huang Shaodan , Xiong Jianyin , Cai Chaorui , Xu Wei , Zhang Yinping
Published: March 2016

Humidity is one of the main environmental factors affecting the emission rate and key parameters of formaldehyde and volatile organic compounds (VOCs) from building materials. Meanwhile, the initial emittable concentration (Cm,0) is proved to be the most sensitive key parameter to the emission behaviours. However, there is no report on the relationship between humidity and Cm,0. In this paper, Cm,0 of formaldehyde and hexaldehyde from a type of medium density fiberboard in absolute humidity (AH) range of 4.6–19.6 g/m3 at 25 °C were tested by virtue of a C-history method. Experimental results indicate that Cm,0 is dramatically dependent on AH, increased by 10 and 2 times for formaldehyde and hexaldehyde when AH rising from 4.6 g/m3 to 19.6 g/m3. A linear relationship between the logarithm of Cm,0 and AH is obtained based on the measured results. In addition, a correlation characterizing the association of emission rate and AH is derived. The effectiveness of the correlation is verified with our experimental results as well as data from literature. With the correlations, the Cm,0 or emission rate different from the test AH conditions can be conveniently obtained. This study should be useful for predicting the emission characteristics of humidity changing scenarios and for source control.
On the dynamics of Liesegang-type pattern formation in a gaseous system
Authors: Ramírez-Álvarez Elizeth , Montoya Fernando , Buhse Thomas , Rios-Herrera Wady , Torres-Guzmán José , Rivera Marco , Martínez-Mekler Gustavo , Müller Markus F.
Published: March 2016

Liesegang pattern formations are widely spread in nature. In spite of a comparably simple experimental setup under laboratory conditions, a variety of spatio-temporal structures may arise. Presumably because of easier control of the experimental conditions, Liesegang pattern formation was mainly studied in gel systems during more than a century. Here we consider pattern formation in a gas phase, where beautiful but highly complex reaction-diffusion-convection dynamics are uncovered by means of a specific laser technique. A quantitative analysis reveals that two different, apparently independent processes, both highly correlated and synchronized across the extension of the reaction cloud, act on different time scales. Each of them imprints a different structure of salt precipitation at the tube walls.
An atomistic view of Hsp70 allosteric crosstalk: from the nucleotide to the substrate binding domain and back
Authors: Chiappori Federica , Merelli Ivan , Milanesi Luciano , Colombo Giorgio , Morra Giulia
Published: March 2016

The Hsp70 is an allosterically regulated family of molecular chaperones. They consist of two structural domains, NBD and SBD, connected by a flexible linker. ATP hydrolysis at the NBD modulates substrate recognition at the SBD, while peptide binding at the SBD enhances ATP hydrolysis. In this study we apply Molecular Dynamics (MD) to elucidate the molecular determinants underlying the allosteric communication from the NBD to the SBD and back. We observe that local structural and dynamical modulation can be coupled to large-scale rearrangements, and that different combinations of ligands at NBD and SBD differently affect the SBD domain mobility. Substituting ADP with ATP in the NBD induces specific structural changes involving the linker and the two NBD lobes. Also, a SBD-bound peptide drives the linker docking by increasing the local dynamical coordination of its C-terminal end: a partially docked DnaK structure is achieved by combining ATP in the NBD and peptide in the SBD. We propose that the MD-based analysis of the inter domain dynamics and structure modulation could be used as a tool to computationally predict the allosteric behaviour and functional response of Hsp70 upon introducing mutations or binding small molecules, with potential applications for drug discovery.
Mechanisms-based viscoplasticity: Theoretical approach and experimental validation for steel 304L
Authors: Zubelewicz Aleksander , Oliferuk Wiera
Published: March 2016

We propose a mechanisms-based viscoplasticity approach for metals and alloys. First, we derive a stochastic model for thermally-activated motion of dislocations and, then, introduce power-law flow rules. The overall plastic deformation includes local plastic slip events taken with an appropriate weight assigned to each angle of the plane misorientation from the direction of maximum shear stress. As deformation progresses, the material experiences successive reorganizations of the slip systems. The microstructural evolution causes that a portion of energy expended on plastic deformation is dissipated and the rest is stored in the defect structures. We show that the reorganizations are stable in a homogeneously deformed material. The concept is tested for steel 304L, where we reproduce experimentally obtained stress-strain responses, we construct the Frost-Ashby deformation map and predict the rate of the energy storage. The storage is assessed in terms of synchronized measurements of temperature and displacement distributions on the specimen surface during tensile loading.
Layered transition metal dichalcogenides: promising near-lattice-matched substrates for GaN growth
Authors: Gupta Priti , Rahman A. A. , Subramanian Shruti , Gupta Shalini , Thamizhavel Arumugam , Orlova Tatyana , Rouvimov Sergei , Vishwanath Suresh , Protasenko Vladimir , Laskar Masihhur R. , Xing Huili Grace , Jena Debdeep , Bhattacharya Arnab
Published: March 2016

Most III-nitride semiconductors are grown on non-lattice-matched substrates like sapphire or silicon due to the extreme difficulty of obtaining a native GaN substrate. We show that several layered transition-metal dichalcogenides are closely lattice-matched to GaN and report the growth of GaN on a range of such layered materials. We report detailed studies of the growth of GaN on mechanically-exfoliated flakes WS2 and MoS2 by metalorganic vapour phase epitaxy. Structural and optical characterization show that strain-free, single-crystal islands of GaN are obtained on the underlying chalcogenide flakes. We obtain strong near-band-edge emission from these layers and analyse their temperature-dependent photoluminescence properties. We also report a proof-of-concept demonstration of large-area growth of GaN on CVD MoS2. Our results show that the transition-metal dichalcogenides can serve as novel near-lattice-matched substrates for nitride growth.
Dimerization of human uridine diphosphate glucuronosyltransferase allozymes 1A1 and 1A9 alters their quercetin glucuronidation activities
Authors: Liu Yan-Qing , Yuan Ling-Min , Gao Zhang-Zhao , Xiao Yong-Sheng , Sun Hong-Ying , Yu Lu-Shan , Zeng Su
Published: March 2016

Uridine diphosphate glucuronosyltransferase 1A (UGT1A) is a major phase II drug-metabolism enzyme superfamily involved in the glucuronidation of endobiotics and xenobiotics in humans. Many polymorphisms in UGT1A genes are reported to inhibit or decrease UGT1A activity. In this study, two UGT1A1 allozymes, UGT1A1 wild-type and a splice mutant, as well as UGT1A9 wild-type and its three UGT1A9 allozymes, UGT1A9*2(C3Y), UGT1A9*3(M33T) and UGT1A9*5(D256N) were single- or double-expressed in a Bac-to-Bac expression system. Dimerization of UGT1A1 or UGT1A9 allozymes was observed via fluorescence resonance energy transfer (FRET) and co-immunoprecipitation analysis. SNPs of UGT1A altered the ability of protein-protein interaction, resulting in differential FRET efficiencies and donor-acceptor r distances. Dimerization changed the chemical regioselectivity, substrate-binding affinity and enzymatic activity of UGT1A1 and UGT1A9 in glucuronidation of quercetin. These findings provide molecular insights into the consequences of homozygous and heterozygous UGT1A1 and UGT1A9 allozymes expression on quercetin glucuronidation.
Substrate complexes of human dipeptidyl peptidase III reveal the mechanism of enzyme inhibition
Authors: Kumar Prashant , Reithofer Viktoria , Reisinger Manuel , Wallner Silvia , Pavkov-Keller Tea , Macheroux Peter , Gruber Karl
Published: March 2016

Human dipeptidyl-peptidase III (hDPP III) is a zinc-dependent hydrolase cleaving dipeptides off the N-termini of various bioactive peptides. Thus, the enzyme is likely involved in a number of physiological processes such as nociception and is also implicated in several forms of cancer. We present high-resolution crystal structures of hDPP III in complex with opioid peptides (Met-and Leu-enkephalin, endomorphin-2) as well as with angiotensin-II and the peptide inhibitor IVYPW. These structures confirm the previously reported large conformational change of the enzyme upon ligand binding and show that the structure of the closed conformation is independent of the nature of the bound peptide. The overall peptide-binding mode is also conserved ensuring the correct positioning of the scissile peptide bond with respect to the catalytic zinc ion. The structure of the angiotensin-II complex shows, how longer peptides are accommodated in the binding cleft of hDPP III. Differences in the binding modes allow a distinction between real substrates and inhibitory peptides or “slow” substrates. The latter displace a zinc bound water molecule necessitating the energetically much less favoured anhydride mechanism as opposed to the favoured promoted-water mechanism. The structural data also form the necessary framework for the design of specific hDPP III inhibitors.
Pramipexole-Induced Hypothermia Reduces Early Brain Injury via PI3K/AKT/GSK3β pathway in Subarachnoid Hemorrhage rats
Authors: Ma Junwei , Wang Zhong , Liu Chenglin , Shen Haitao , Chen Zhouqing , Yin Jia , Zuo Gang , Duan Xiaochun , Li Haiying , Chen Gang
Published: March 2016

Previous studies have shown neuroprotective effects of hypothermia. However, its effects on subarachnoid hemorrhage (SAH)-induced early brain injury (EBI) remain unclear. In this study, a SAH rat model was employed to study the effects and mechanisms of pramipexole-induced hypothermia on EBI after SAH. Dose-response experiments were performed to select the appropriate pramipexole concentration and frequency of administration for induction of mild hypothermia (33–36 °C). Western blot, neurobehavioral evaluation, Terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) and Fluoro-Jade B (FJB) staining were used to detect the effects of pramipexole-induced hypothermia on SAH-induced EBI, as well as to study whether controlled rewarming could attenuate these effects. Inhibitors targeting the PI3K/AKT/GSK3β pathway were administered to determine whether the neuroprotective effect of pramipexole-induced hypothermia was mediated by PI3K/AKT/GSK3β signaling pathway. The results showed that intraperitoneal injection of pramipexole at 0.25 mg/kg body weight once per 8 hours was found to successfully and safely maintain rats at mild hypothermia. Pramipexole-induced hypothermia ameliorated SAH-induced brain cell death, blood-brain barrier damage and neurobehavioral deficits in a PI3K/AKT/GSK3β signaling-dependent manner. Therefore, we may conclude that pramipexole-induced hypothermia could effectively inhibit EBI after SAH in rats via PI3K/AKT/GSK3β signaling pathway.
Overexpression of SlUPA-like induces cell enlargement, aberrant development and low stress tolerance through phytohormonal pathway in tomato
Authors: Cui Baolu , Hu Zongli , Hu Jingtao , Zhang Yanjie , Yin Wencheng , Zhu Zhiguo , Feng Ye , Chen Guoping
Published: March 2016

upa20 induces cell enlargement and hypertrophy development. In our research, overexpression of SlUPA-like, orthologous to upa20, severely affected the growth of vegetative and reproductive tissues. Wilted leaves curled upwardly and sterile flowers were found in transgenic lines. Through anatomical analysis, palisade and spongy tissues showed fluffy and hypertrophic development in transgenic plants. Gene expression analysis showed that GA responsive, biosynthetic and signal transduction genes (e.g. GAST1, SlGA20OXs, SlGA3OXs, SlGID1s and SlPREs) were significantly upregulated, indicating that GA response is stimulated by overproduction of SlUPA-like. Furthermore, SlUPA-like was strongly induced by exogenous JA and wounding. Decreased expression of PI-I and induced expression of SlJAZs (including SlJAZ2, SlJAZ10 and SlJAZ11) were observed in transgenic plants, suggesting that JA response is repressed. In addition, SlUPA-like overexpressed plant exhibited more opened stoma and higher water loss than the control when treated with dehydration stress, which was related to decreased ABA biosynthesis, signal transduction and response. Particularly, abnormal developments of transgenic plants promote the plant susceptibility to Xanthomonas campestris pv. campestris. Therefore, it is deduced from these results that SlUPA-like plays vital role in regulation of plant development and stress tolerance through GA, JA and ABA pathways.
Effects of carbon vacancies on the structures, mechanical properties, and chemical bonding of zirconium carbides: a first-principles study
Authors: Xie Congwei , Oganov Artem R. , Li Duan , Debela Tekalign Terfa , Liu Ning , Dong Dong , Zeng Qingfeng
Published: March 2016

The distribution of carbon vacancies has a great effect on Pugh's ratio of interstitial carbides.
On-chip droplet production regimes using surface acoustic waves
Authors: Brenker Jason C. , Collins David J. , Van Phan Hoang , Alan Tuncay , Neild Adrian
Published: March 2016

Aqueous droplets suspended in an immiscible carrier fluid are a key tool in microfluidic chemical analysis platforms.
Cross-linked methyl cellulose/graphene oxide rate controlling membranes for in vitro and ex vivo permeation studies of diltiazem hydrochloride
Authors: Sarkar Gunjan , Saha Nayan Ranjan , Roy Indranil , Bhattacharyya Amartya , Adhikari Arpita , Rana Dipak , Bhowmik Manas , Bose Madhura , Mishra Roshnara , Chattopadhyay Dipankar
Published: March 2016

Permeability characteristics of the anti-hypertensive drug, diltiazem hydrochloride, from uncross-linked and cross-linked methylcellulose (MC)/graphene oxide (GO) rate controlling membranes (RCMs) were investigated.
Thermo-responsive polymer aided spheroid culture in cryogel based platform for high throughput drug screening
Authors: Sarkar J. , Kumar A.
Published: March 2016

A versatile and widely applicable cryogel-based high throughput platform for spheroid culture in the presence of a thermo-responsive polymer and drug screening.
Synthesis of 3-fluoroalkenyl-3-trifluoromethyl-2-oxindoles by the reaction of indoline-2,3-diones with difluoromethylene phosphabetaine
Authors: Liu Yingle , Zhang Ke , Huang Yangen , Pan Shen , Liu Xiao-Qiang , Yang Yi , Jiang Yan , Xu Xiu-Hua
Published: March 2016

The reaction of indoline-2,3-diones and (triphenylphosphonio)difluoroacetate (PDFA) afforded novel 3-fluoroalkenyl-3-trifluoromethyl-2-oxindoles in moderate to excellent yields.
A TICT-based fluorescent probe for rapid and specific detection of hydrogen sulfide and its bio-imaging applications
Authors: Ren Mingguang , Deng Beibei , Kong Xiuqi , Zhou Kai , Liu Keyin , Xu Gaoping , Lin Weiying
Published: March 2016

Through rational design, the first TICT based fluorescent H2S probe was developed, which exhibited ideal properties such as fast response, good selectivity, high sensitivity, and it was suitable for visualization of exogenous and endogenous H2S in living cells.
Facile stabilization of cyclodextrin metal–organic frameworks under aqueous conditions via the incorporation of C60 in their matrices
Authors: Li Haiqing , Hill Matthew R. , Huang Runhong , Doblin Christian , Lim Seng , Hill Anita J. , Babarao Ravichandar , Falcaro Paolo
Published: March 2016

A facile method to improve the stability of γ-cyclodextrin metal–organic frameworks in an aqueous environment has been developed through the incorporation of hydrophobic C60 in their matrices.
Novel chemoselective 18F-radiolabeling of thiol-containing biomolecules under mild aqueous conditions
Authors: Chiotellis Aristeidis , Sladojevich Filippo , Mu Linjing , Müller Herde Adrienne , Valverde Ibai E. , Tolmachev Vladimir , Schibli Roger , Ametamey Simon M. , Mindt Thomas L.
Published: March 2016

[18F]FPOS: a novel prosthetic group for the chemoselective 18F-radiolabeling of thiol-containing biomolecules under mild aqueous conditions.
Serpentine polymorphism: a quantitative insight from first-principles calculations
Authors: Demichelis Raffaella , De La Pierre Marco , Mookherjee Mainak , Zicovich-Wilson Claudio M. , Orlando Roberto
Published: March 2016

Ab initiocalculations measure strain energy, curling and lattice misfit of single-walled chrysotile nanotubes.
Design, synthesis and anti-proliferative activities of novel 7′-O-substituted schisantherin A derivatives
Authors: Venkanna A. , Kumar Ch. Pavan , Poornima B. , Siva Bandi , Jain Nishant , Suresh Babu K.
Published: March 2016

A series of schisantherin A (1) derivatives were efficiently synthesized utilizing Yamaguchi esterification (2,4,6-trichlorobenzoyl chloride, Et3N, THF, DMAP, toluene) at the C-7′ position of the schisantherin A core.
Effects of the multiple O-glycosylation states on antibody recognition of the immunodominant motif in MUC1 extracellular tandem repeats
Authors: Rangappa Shobith , Artigas Gerard , Miyoshi Risho , Yokoi Yasuhiro , Hayakawa Shun , Garcia-Martin Fayna , Hinou Hiroshi , Nishimura Shin-Ichiro
Published: March 2016

The conformational impact of the clusteredO-glycans strongly influences recognition by antibodies of the cancer-relevant epitope in the MUC1 extracellular tandem repeat domain.
Synthesis and biological evaluation of new spirooxindoles with embedded pharmacophores
Authors: Mathusalini Sadasivam , Arasakumar Thangaraj , Lakshmi Krishnasamy , Lin Chia-Her , Mohan Palathurai Subramaniam , Ramnath Madhusudhanan Gogul , Thirugnanasampandan Ramaraj
Published: March 2016

The newly synthesized spirooxindole derivatives have shownin vitroantioxidant, antidiabetic and acetylcholinesterase inhibitory activities.