bluuebunny/crossref_metadata_2025 huggingface dataset:
Soft X-Ray Images of the Solar Corona Using Normal Incidence Optics
Authors: Bruner M.E. , Haisch B.M. , Brown W.A. , Acton L.W. , Underwood J.H.
Published: July 2016

A solar coronal loop system has been photographed in soft X-rays using a normal incidence telescope based on multilayer mirror technology. The telescope consisted of a spherical objective mirror of 4 cm aperture and 1 m focal length, a film cassette, and a focal plane shutter. A metallized thin plastic film filter was used to exclude visible light. The objective mirror was covered with a multilayer coating consisting of alternating layers of tungsten and carbon whose combined thicknesses satisfied the Bragg diffraction condition for 44 Å radiation. The image was recorded during a rocket flight on 1985 October 25, and was dominated by emission lines arising from the Si XII spectrum. The rocket also carried a high resolution soft X-ray spectrograph that confirmed the presence of Si XII line radiation in the source. This image represents the first successful use of multilayer technology for astrophysical observations.
Review of X-ray Spectroscopy from Laser-Produced Plasmas
Authors: Kauffman R.L.
Published: July 2016

Recent progress in x-ray spectroscopy from laser plasmas is reviewed. Advances in the use of K-shell spectra as a diagnostic tool is discussed. Much activity in understanding complex spectra especially from Ne I and Ni I isoelectronic series have been made. Much of the progress has been due to observation of amplification from Δn=0 transitions from these configurations. The spectroscopy will be discussed and examples of spectra of the amplified lines will be shown. Finally, recent work on using x-ray spectroscopy to diagnose high density implosions will be discussed.
Spectroscopic Diagnostics of Tokamaks
Authors: de Michelis C.
Published: July 2016

Impurities being an important concern in tokamaks, spectroscopy plays a key role in their understanding. Techniques for the evaluation of concentrations, power losses and transport properties are surveyed, and a few developments are outlined.
Continuous Ultraviolet Absorption BY Si+(4Pe): an Exploratory R-Matrix Calculation
Authors: Tully J.A.
Published: July 2016

The R-matrix method is used to calculate photoionisation from the first excited state 3s3p23Pe of Si+. The lowest two triplet terms 3s3p3Poand 3p23Peof the residual ion Si++are included in the calculation. They are approximated by configuration interaction wavefunctions which are constructed from six spectroscopic orbitals: 1s,2s,2p,3s,3p,3d. Partial and total cross-sections are tabulated for photon energies ranging from threshold (705 A) up to 2.5 Ryd (365 A). Some of the 3p2np autoionising resonances are delineated and shown graphically.
The Diagnostics of Astrophysical Plasmas, using the Oxygen VII Soft X-Ray Lines
Authors: Gabriel A.H. , Bely-Dubau F. , Faucher P. , Acton L.W.
Published: July 2016

We present a revised theory and atomic model for the line intensities emitted by O VII, taking into account all of the processes responsible for the emission. This is used to provide a revision of the density measurements made during solar flares, as well as in an attempt to understand the spectrum of the Puppis A supernova remnant. In order to explain the strange intensity ratios observed from Puppis A, previous authors have proposed an interpretation based upon a high temperature thermal plasma (>5 106K), in a non-equilibrium ionisation state. We present here an alternative model, based upon the assumed presence of a proportion of fast non-thermal electrons imbedded in an otherwise thermal plasma at a temperature of below 1 106K. This can adequately explain the observations, without the necessity of invoking departures from ionisation balance.
Determination of Space and Time Resolved Plasma Diagnostics in Laser Produced Plasmas
Authors: Cauble R. , Lee R.W.
Published: July 2016

Spectroscopic data from a variety of Nd glass laser-irradiated planar targets is examined. The experiments were performed for a number of purposes, including development of intense x-ray sources for absorption studies important in ICF, as well as investigations of target material properties. The data are examined with the non-LTE atomic rate equation code package, RATION. RATION solves for and displays detailed theoretical spectra for a number of H-like, He-like, and Li-like atomic transitions and is presently available to users of the MFE Computer Center network. The package has been enhanced to include a larger number of Li-like levels, some in full detail, and the ability to include time-dependent and space-dependent hydrodynamic information. The main results are spectral line ratios and displays of the full spectrum employing the RATION atomic model. Using these tools, time- and space-dependent plasma temperature and density diagnostics are produced and compared with the experimental data.
Quick Interpretation of Unresolved Hyperfine and/or Zeeman Structures in Stellar Spectra
Authors: Bauche J. , Oreg J.
Published: July 2016

Some atomic or ionic lines emitted by the stellar atmospheres are very useful clues for estimating the local magnetic fields. However, their use is often complicated by insufficient experimental resolution and by the occurence of hyperfine structure. But the average wavelength and the width of the component set corresponding to each type of polarisation are given by compact formulae, in terms of the magnetic field, and of the Landé factors and hyperfine magnetic and electric constants of both involved levels.
Results of the Leban Diagnostic Procedure Applied to Two SMM - Observed Flares
Authors: Sylwester B. , Sylwester J. , Jakimiec J.
Published: July 2016

In a previous paper (B. Sylwester et al., 1986) we proposed a new procedure called LEBAN (Loop Energy Balance Analysis) for deriving the basic geometrical parameters of flaring loops. In a subsequent paper (B. Sylwester et al., 1987) the Palermo Code resuits of hydrodynamic flare loop modelling have been used to confirm the validity of the LEBAN procedure for this purpose. In the present investigation the LEBAN procedure has been applied to analyse two SMM-observed flares (on 12 Nov. 1980, ∼17:00 UT and on 18 Nov. 1980, ∼15:00 UT). Estimated flare loop lengths and cross-sections have been compared with those derived from deconvolved HXIS images and/or estimated in different way by other authors. If the loop semi-length L is known from other observations, this allows to estimate the portionβof the loop which was heated. Time variations of other important parameters characterizing the flare plasma (the heating rate, the mean density, the total energy content) are also discussed.
Theoretical Spectra of Fe XXIII - Fe XIX Ions in Two Calculation Methods
Authors: Cornille M. , Dubau J. , Loulergue M. , Bely-Dubau F. , Faucher P. , Safronova U.I. , Shlyaptseva A.S.
Published: July 2016

Two different calculation methods are compared for Fe XXIII – Fe XIX spectra in the X-ray range between 1.85–2 Å, for transitions of the type 1s2sk2pn−1s22sk2pn−1. Wavelengths, radiative transition and autoionization probabilities as well as the intensity factors are compared. These parameters are given in order to diagnosis low density plasmas as found in solar flares and Tokamak devices.
Axial Observation of X-Ray Spectra from a Beam-Foil Source
Authors: Laming J.M. , Silver J.D. , Barnsley R. , Dunn J. , Evans K.D. , Peacock N.J.
Published: July 2016

New observations of x-ray spectra from foil-excited heavy ion beams are reported. By observing the target in a direction along the beam axis, an improvement in spectral resolution, δλ/λ, by about a factor of two is achieved, due to the reduced Doppler broadening in this geometry.
A Perturbation Theory for the Population of Atomic Energy Levels in Non-Lte Plasmas
Authors: Klapisch M.
Published: July 2016

A formal expansion of the CRM in powers of a small parameter is presented. The terms of the expansion are products of matrices. Inverses are interpreted as effects of cascades.It will be shown that this allows for the separation of the different contributions to the populations, thus providing a natural classification scheme for processes involving atoms in plasmas. Sum rules can be formulated, allowing the population of the levels, in some simple cases, to be related in a transparent way to the quantum numbers.
VUV Spectroscopy of Ar9+ and Kr9+ Low Energy Collision with H2
Authors: Druetta M. , Bouchama T. , Martin S. , Désesquelles J.
Published: July 2016

Photon spectroscopy of low energy collisions between multicharged ions and neutrals has opened new possibilities of wavelength and energy level determination since recent multicharged ion sources like the E.C.R. source, giving μA electric current of highly multicharged ions, are available.

The experimental set-up has been already described (1.2) The ion beam is produced by an E.C.R. ion source. Light emitted as a result of the collision is observed at 25* to the beam axis with a 3m grazing incidence (82*) spectrometer equipped with a 300 or 600 lines/mm grating blazed at 55.2 or 27.6 nm respectively. The detection is realised by micro-channel plates (MCP). Typical beam currents are 0.45 and 0.40 μA for Kr9+and Ar9+respectively, through the 8 mm diameter entrance hole of the gas cell. The gas pressure was kept at 5 × 10−5mbar. The emission cross sections of all the new observed lines have been mesured. Taking into account the statistics; the error on the beam intensity due to double collisions; the errors on the pressure, on the relative efficiency curve of the spectrometer and on the absolute calibration; we may estimate the error bar to ± 30%.
Doppler Shift in X-Ray Spectrum for Laser-Imploded Spherical Microshells
Authors: Fiedorowicz H. , Denus S. , Jeziak K. , Kolanowski M. , Parys P. , Pawłowicz W. , Wołowski J.
Published: July 2016

Doppler shifts due to plasma motion have been observed in the space-resolved X-ray spectra for the laser-imploded spherical microshells. The analysis of the X-ray spectrum makes it possible to study the ablation process from the microshell surface.
Mirrors: Fabrication, Processing, Testing and Tolerances
Authors: Meinel A.B. , Meinel M.P. , Shannon R.R. , Parks R.E.
Published: July 2016

The construction of very large telescopes is impeded by very large costs. Much effort is going into finding ways to get below the traditional cost-scaling trend line. We will address several factors that lead to reduction in cost without reduction in performance. Clearly, a very fast primary f-ratio is necessary. The practical lower limit is set by three factors:

1) width of the Nasmyth platform

2) new optical processing techniques

and 3) maintenance of collimation.
Pointing Errors of Large Telescopes Due to Wind
Authors: Ulich Bobby L.
Published: July 2016

Scaling laws are presented which show the dependence of the tracking error of large telescopes on structural materials, mechanical properties and dimensions of the mount, and wind speed. Based on direct measurements on the Multiple Mirror Telescope, predictions are made for future very large telescopes. It is shown that good tracking can be achieved most of the time even without a traditional dome to block the wind, and this may result in better images by eliminating “dome seeing”.
Large European Solar Telescope (LEST) - a Solar Telescope for High Spatial Resolution and Polarimetric Observations
Authors: Engvold Oddbjørn
Published: July 2016

In 1969 European solar physists formed the Joint Organization for Solar Observation (JOSO). The goals of JOSO were to find an, ideal site for a large solar instrument, and to create an observatory on this site equipped with a solar telescope for high spatial resolution and polarimetric observations. This instrument is referred to by the acronym LEST which stands for Large European Solar Telescope.
Pathlength Stability of Synthetic Aperture Telescopes - the Case of the 25 cm CERGA Interferometer
Authors: Mariotti J.M. , Di Benedetto G.P.
Published: July 2016

Synthetic aperture telescopes are more and more considered as a promising scheme for the next generation of Very Large Telescopes : the basic idea is to combine the beams of two or more independent telescopes. The question immediately raising when considering such a technique is the pathlength stability and the amount of pathlength difference that can be tolerated, assuming a reasonable bandwidth, to preserve coherent addition of the wavefronts and hence, high spatial frequencies observations.

To that respect the I2T (two telescopes interferometer) in operation at CERGA constitutes a remarkable test-bench for studies of mechanical, optical and atmospheric constraints that are to be faced when dealing with amplitude interferometry between several telescopes.
16 m Large Slit Aperture Telescope for Very High Angular Resolution Astronomy
Authors: Petrov R.G. , Aime C. , Borgnino J. , Martin F. , Ricort G.
Published: July 2016

The expected progress of diffraction limited imaging methods and the apparition of new super resolution techniques like differential speckle interferometry would justify the construction of a 15 m class telescope dedicated to diffraction limited observations in order to fulfil the potential of high angular resolution astrophysics of 15 m class instruments, but the construction of such a telescope is conceivable only if its cost is much smaller than the cost of the equivalent all purposes VLT. In this paper we suggest that a telescope with a long and thin rectangular primary ( 16 m X.4m say ) , able to rotate around the optical axis to ensure a full coverage of the frequency plane, would do almost as well than a conventional 16 m aperture telescope for high angular resolution astronomy for a cost substancially reduced. The performances of such a Large Slit Aperture Telescope ( LSAT ) for classical and differential speckle interferometry are examined and the releases on the optical and mechanical constraints allowed by the dedication of the instrument to speckle techniques are discussed.
The Mersenne-Schmidt Telescope
Authors: Willstrop R.V.
Published: July 2016

A three-mirror telescope is described which covers a field 4° in diameter at f/1.6 with images smaller than 0.31 arcsec total spread (0.17 arcsec r.m.s.); an alternative version, also f/1.6, covers a field 2° in diameter with images smaller than 0.049 arcsec (0.023 arcsec r.m.s.). Both forms of this telescope are fully baffled against sky fog contamination, the illumination is uniform over the central 2° field and decreases by about 13 per cent at the edge of the 4° field, and the tube length is little more than the focal length.
Optical and Infrared Instruments Requirements for a VLT
Authors: Butcher Harvey R.
Published: July 2016

I have been asked to remark on the instrumentation which, at least from the viewpoint of the 1980's, seems most important for early implementation on a VLT in the 1990's. To avoid simply making a long list of many possibilities, each of which has some advantage over its competitors, I will divide the discussion into three parts: a summary of the principal observational advances made possible by a VLT in the 15-20 meter class; a list of what is arguably the resulting basic set of needed instruments; and a brief consideration of the telescope design features, technology development programs, and political/financial efforts required to make those instruments a reality.
System Requirements for Polarization Capability
Authors: Tinbergen J.
Published: July 2016

The purpose of this paper is to point out that

1) proper treatment of polarization by a telescope is not only important for polarimetry, but also for other observations requiring high signal-to-noise ratio, and

2) this does put a constraint on telescope design, which, however, is not unduly restrictive.

Polarimetry is the observational technique which can detect anisotropics in point sources, their environment, or the medium between them and us. Modern optical polarimetry can be linear or circular, and is making progress towards spectropolarimetry and imaging polarimetry using panoramic detectors (e.g. McLean, 1984). Given sufficient photons, the precision obtained is as high as 1 part in 50 000 (see Odell, 1981 for a project requiring this precision), but more often a precision between 1 part in 1 000 to 10 000 is sufficient. (Spectro)polarimetry has been applied to planets, the Sun and other stars, stellar systems and galaxy nuclei; for a few modern investigations, see Baur, 1981; Jones et al, 1981; Schmidt and Miller, 1980. Experience in radio-astronomy has shown that when facilities for polarimetry are offered, many applications emerge from the astronomical community, yielding data that cannot be obtained by other techniques. It is essential that at least some of the large optical telescopes are capable of ob-serving polarization cleanly.
Two-Dimensional Infrared Detector Arrays
Authors: McCreight C.R.
Published: July 2016

The technology and terminology of integrated infrared detector arrays are discussed. Specific infrared array multiplexer designs include the charge-coupled device (CCD) and charge-injection device (CID). Laboratory data and telescope imagery obtained with three arrays (inSb CCD, Si:In CCD, and Si:Bi CID) are used to illustrate the performance and promise of integrated arrays in astronomical applications.
Very Large Telescopes and Stellar Astrophysics
Authors: Castellani Vittorio
Published: July 2016

Let me start by reminding you in a very general frame what kind of information we expect to be able to derive from the observation of stars.

First of all, there are observations - of photometric nature - which allow us to detect the location of stars in the sky. Modern astrophysics enables us, in the general case, to add more or less stringent information on the star distances. On the whole, one reaches in this way a picture of the galactic distribution of stars, i.e. information on the space location.

A second kind of information we can derive from photometric measurements is that concerned with the age of stellar objects. As is well known, this is done - mainly - by constructing HR diagrams for stars which are members of stellar clusters.
Uses of Very Large Telescopes for Galaxy Research
Authors: Ulrich M.-H.
Published: July 2016

Many areas of extragalactic research will greatly benefit from observations with a very large telescope. We concentrate, here, on four of them as illustrative examples:

First we briefly discuss the study of the absorption lines in quasar spectra.

In the second section we suggest the possibility of doing serendipity large field imaging during high spectral resolution exposures on point sources.

In sections 3 and 4 we discuss two topics which have long been recognized as important drivers for the construction of very large telescopes, the determination of the nature of the missing mass, and the study of elliptical galaxies.
ESO 16 Metre Very Large Telescope: The Linear Array Concept
Authors: Enard Daniel
Published: July 2016

VLT preliminary studies were initiated at ESO as early as 1978 (1). After ESO's move from Geneva to Munich (1980) a study group chaired first by R. Wilson, then by J.P. Swings was set up and among a number of conceptual ideas that were analysed, the concept of a “limited array” emerged as the most attractive (2). A significant driver was then, interferometry; however after a theoretical analysis performed by F. Roddier and P. Lena (3), it became clear that interferometry with large telescopes would not be cost-effective in the visible range. In the IR, the situation would be more favorable but the overall efficiency would depend on factors that are not reliably known at present. The conclusion was that it might be difficult to justify a huge investment too exclusively oriented towards interferometry, such as an array of movable large telescopes, but on the other hand the possibility of a coherent coupling in the IR should be maintained as a prime requirement since new developments in detectors and in adaptive optics could make it effective and scientifically very rewarding.
The University of Texas 7.6-m Telescope
Authors: Tull Robert G.
Published: July 2016

In late 1979 a plan to build a very large telescope was presented to University of Texas President Peter Flawn. A small startup budget was subsequently granted by the University administration, and we asked Aden and Marjorie Meinel to carry out a design concept study, which they completed in early 1980. Following their report, a study contract was awarded to the Western Development Laboratories Division of Ford Aerospace & Communications Corp., for a preliminary design and cost estimate.

It is generally agreed that construction of monolithic mirrors up to 8-10 meters aperture is within current technology. The major concern that has prevented construction of telescopes larger than the Palomar 5-m telescope outside the Soviet Union has been cost; it has been shown (Meinel and Meinel, 1980a) that the single most important item in determining the cost of a large telescope is the weight of its primary mirror. We chose a monolithic, lightweight 7.6-m (300-inch) mirror as representing a significant advance from presently existing telescope apertures while also being well within the current state-of-the-art. Because a lightweight mirror cannot support its figure against gravity and other disturbances as well as can a conventional thick mirror, we have investigated methods of active control of the mirror's figure. The now maturing technology of adaptive optics (Hardy 1980, 1981, 1982) has been drawn upon extensively in planning this telescope. Results of finite element analyses of an ultra-lightweight monolithic 7.6-m mirror blank have been published (Ray et.al., 1982, 1983). A description of the proposed mirror figure monitoring system has been given (Tull and Young, 1983).
The Double-Mode Cepheids
Authors: Balona L. A.
Published: July 2016

Recent observations of double-mode Cepheids and proposed candidates are reviewed. It appears that the change of modal content reported in some stars may not be real. Observations show that the double-mode Cepheids are indistinguishable from normal Cepheids of similar period. This poses a severe problem for pulsation theory which predicts very low masses from the ratio of first overtone to fundamental period. Attempts to resolve this problem and the problem of modal selection are discussed.
Infrared Observations of Galactic Cepheids
Authors: Fernley J. A. , Jameson R. F. , Sherrington M. R.
Published: July 2016

Infrared photometry enables radii, and hence absolute magnitudes, to be derived more accurately than is possible using purely optical photometry. In this paper we present BVJHK observations of the galactic cepheids T Vul, U Vul and T Mon. Using this data we find reasonable agreement with current versions of the Period-Luminosity relations, in both the optical and infrared.

From these relations and existing optical and infrared data for LMC Cepheids we find for the LMC (i) Av = 0.35 and (ii) a distance modulus of 18.50. In addition we show that the P-L-C relation has the form

 = – 3.10 log P + 1.70 (–) – 2.37
Classical Cepheids: Period Changes and Mass Loss
Authors: Deasy H.
Published: July 2016

The period is an ideal parameter for monitoring minute changes in the structure of a star passing through the instability strip, as it can be measured with an accuracy of up to one part per million. The view of Parenago (1956) that only abrupt period changes occur in cepheids is no longer prevalent, and it is generally accepted that random period changes are superposed on the secular variation due to evolution. One possible mechanism for the random fluctuations in period or phase is convection or semiconvection, which Sweigert & Renzini (1979) showed could account for the period changes of RR Lyrae stars. Other mechanisms include the influence of binary companions and mass loss. The latter mechanism forms the basis for a separate study involving the use of IUE spectra to search for evidence of matter being ejected from cepheids.
Duplicity, Mass Loss and the Cepheid Mass Anomaly
Authors: Burki G.
Published: July 2016

The rate of binaries among cepheid stars is 25 - 35% (Burki, 1984a), a value which is in agreement with the rate among F-M supergiants (31-38%) obtained by Burki and Mayor (1983) from a radial velocity survey.

For binary cepheids, the Wesselink radius RW is affected by the light of the companion. Balona (1977) found that RW is too small if the companion is a blue main sequence star and too large if it is a red giant star. This effect has been quantitatively examined by Burki (1984a). For example, it was found that, in the case of a cepheid of period P = 32d with a companion fainter by 2 mag., RW is 70% of its correct value if we are dealing with a main sequence companion and 130% in the case of a companion redder by 0.6 in B-V. The bias on RW becomes negligible when the companion is fainter than the cepheid by more than 4 mag.
A Search For Cepheid Binaries Using the Call H And K Lines
Authors: Evans Nancy Remage
Published: July 2016

A survey of 24 classical Cepheids has been made to search for blue companions using the Call H and K lines. It is shown that this technique can detect an early A companion for a typical Cepheid. A blue companion of SU Cas was discovered and upper limits for the companions for a number of previously suspected binaries were established.
Theoretical Study of Cepheid Light Curves
Authors: Davis C. G.
Published: July 2016

Starting with the initial understanding that pulsation in variable stars is caused by the heat engine of Hydrogen and Helium ionization in their atmospheres (A.S. Eddington in Cox 1980) it was soon realized that non-linear effects were responsible for the detailed features on their light and velocity curves. With the advent of the computer we were able to solve the coupled set of hydrodynamics and radiation diffusion equations to model these non-linear features (Christy 1968, Cox et. al. 1966). Calculations including the effects of multi-frequency radiative transfer (Davis 1975) showed that grey diffusion was adequate for modeling Cepheids but not for the RR Lyrae or W Virginis type variables.
Some Remarks Concerning the Accuracy of Photometric Reddenings for Classical Cepheids
Authors: Turner D. G.
Published: July 2016

Considerable effort has been spent over the years in deriving colour excesses for classical Cepheids using their observed photometric indices. Various broad band, intermediate band, and narrow band systems have been used for this purpose, all with varying degrees of success. Reddenings derived in this manner are extremely useful, and most of the factors which limit their accuracy seem to be reasonably well known. Two others, which often tend to be overlooked but which are addressed here, are the presence of photometric companions to many Cepheids and the tendency to treat interstellar reddening in a prescriptive manner. The point is not necessarily to raise doubts about the validity of published photometric reddenings for classical Cepheids, but rather to examine the possibility that one can derive slightly more reliable colour excesses using the available observational data.
Leavitt Variables: The Brightest Cepheids Variables and their Implications for the Distance Scale
Authors: Grieve Gerald R. , Madore Barry F. , Welch Douglas L.
Published: July 2016

Two low-amplitude variable supergiants in the Large Magellanic Cloud, S65-08 and S65-48 are each found to have periods of approximately 250 days. The cfptical data suggest that these stars are high-luminosity cepheid variables falling more than one magnitude brighter than any other known Cepheids in the LMC. Confirmation of the cepheid nature of these stars comes from their H-band magnitudes which place them accurately on a simple linear extrapolation of the narrower infrared Period-Luminosity relation. So it appears that the cepheid Period-Luminosity relation extends up to Mv ~ -8.5. To honour the astronomer who discovered the first of these highest-liminosity Cepheids, we have sub-classified the variables with log P > 1.8 as being “Leavitt variables”. As soon as these long-period variables are discovered in other external galaxies, reliable distances should be possible out to (m-M) ~30.
Hydrodynamic Models of Population II Cepheids
Authors: Fadeyev Yu.A. , Fokin A. B.
Published: July 2016

This is a short report on hydrodynamic modelling for BL Her and W Vir pulsating variables. We present only a qualitative summary of the results obtained, whereas detailed paper will appear soon.

We studied radial self-exciting stellar oscillations with convection ignored. The Massevitch I mixture (X=0.7, Z=0.004) was assumed for calculating the opacity coefficient. All models have a mass M=0.6Mʘ, but their absolute magnitudes are in the range from -0.5 to -3 mag. The study covers the period range from 1.3 to 20 days.
Two Mid-Giant Branch Stars in M15
Authors: Chu Y-H , Clement C. M. , Hogg H. Sawyer , Wells T. R.
Published: July 2016

High precision photographic photometry indicates that two stars lying on the giant branch in the C-M diagram of M15 are small amplitude (~0.2 mag) variables. The two stars are Kustner 64 and 152. This investigation is based on plates taken with three telescopes: the Dominion Astrophysical Observatory 1.8-metre reflector, the David Dunlap 1.9-metre reflector and the Yunnan 1-metre reflector in China. The existing data is not sufficient for period determination.
Physical Properties of Frozen Volatiles–Their Relevance to the Study of Comet Nuclei
Authors: Klinger J.
Published: July 2016

The structural and thermodynamical properties of water ice and ice mixtures containing CO, CO2, CH4, and NH3 are thought to be important for the evolution of cometary nuclei. Based on recent laboratory studies performed by several groups, an overview is given of the properties of various ices condensed at low temperatures and of their evolution during heating up to a temperature of about 200 K, typical of the perihelion temperature of a comet such as P/Halley. It is shown that the porous surface of amorphous water ice plays an important role in the retention of other volatiles. The kinetics of formation and of decomposition of clathrate hydrates are discussed. The molecular hydrates formed by NH3 are briefly presented, and the possibility of their occurrence in comet nuclei is discussed. With special attention drawn to amorphous ices and clathrate hydrates, a qualitative discussion of the influence of the physical properties of various types of ices on the thermal behavior of comet nuclei and on gas production rates of comets is presented.
Do Muslim Women Need Freedom? Traditionalist Feminisms and Transnational Politics
Authors: Khader Serene J.
Published: July 2016

The idea that Muslim women need to be liberated from religion and tradition has animated feminist support for imperialist projects. The idea that tradition itself is women's oppressor prevents Western feminists from perceiving cultural and religious destruction as potentially harmful. In this article, I make conceptual space for traditionalist feminisms by showing that feminism does not require any particular stance toward tradition as such. What should matter to feminists is whether the content of a given tradition is oppressive—not whether it belongs to a worldview that places a high value on traditional adherence. I show this by arguing that, contra some liberal feminists, opposition to sexist oppression does not entail value for what I call “Enlightenment freedom.” I draw on Islamic feminisms to demonstrate the possibility of opposition to sexist oppression grounded in worldviews that value traditional adherence, and even ones that hold certain traditional dictates to be beyond question.
Granzyme M has a critical role in providing innate immune protection in ulcerative colitis
Authors: Souza-Fonseca-Guimaraes F , Krasnova Y , Putoczki T , Miles K , MacDonald K P , Town L , Shi W , Gobe G C , McDade L , Mielke L A , Tye H , Masters S L , Belz G T , Huntington N D , Radford-Smith G , Smyth M J
Published: July 2016

Inflammatory bowel disease (IBD) is an immunoregulatory disorder, associated with a chronic and inappropriate mucosal immune response to commensal bacteria, underlying disease states such as ulcerative colitis (UC) and Crohn’s disease (CD) in humans. Granzyme M (GrzM) is a serine protease expressed by cytotoxic lymphocytes, in particular natural killer (NK) cells. Granzymes are thought to be involved in triggering cell death in eukaryotic target cells; however, some evidence supports their role in inflammation. The role of GrzM in the innate immune response to mucosal inflammation has never been examined. Here, we discover that patients with UC, unlike patients with CD, display high levels of GrzM mRNA expression in the inflamed colon. By taking advantage of well-established models of experimental UC, we revealed that GrzM-deficient mice have greater levels of inflammatory indicators during dextran sulfate sodium (DSS)-induced IBD, including increased weight loss, greater colon length reduction and more severe intestinal histopathology. The absence of GrzM expression also had effects on gut permeability, tissue cytokine/chemokine dynamics, and neutrophil infiltration during disease. These findings demonstrate, for the first time, that GrzM has a critical role during early stages of inflammation in UC, and that in its absence colonic inflammation is enhanced.
Quantum coherent tractor beam effect for atoms trapped near a nanowaveguide
Authors: Sadgrove Mark , Wimberger Sandro , Nic Chormaic Síle
Published: July 2016

We propose several schemes to realize a tractor beam effect for ultracold atoms in the vicinity of a few-mode nanowaveguide. Atoms trapped near the waveguide are transported in a direction opposite to the guided mode propagation direction. We analyse three specific examples for ultracold 23Na atoms trapped near a specific nanowaveguide (i.e. an optical nanofibre): (i) a conveyor belt-type tractor beam effect, (ii) an accelerator tractor beam effect and (iii) a quantum coherent tractor beam effect, all of which can effectively pull atoms along the nanofibre toward the light source. This technique provides a new tool for controlling the motion of particles near nanowaveguides with potential applications in the study of particle transport and binding as well as atom interferometry.
Cable energy function of cortical axons
Authors: Ju Huiwen , Hines Michael L. , Yu Yuguo
Published: July 2016

Accurate estimation of action potential (AP)-related metabolic cost is essential for understanding energetic constraints on brain connections and signaling processes. Most previous energy estimates of the AP were obtained using the Na+-counting method, which seriously limits accurate assessment of metabolic cost of ionic currents that underlie AP conduction along the axon. Here, we first derive a full cable energy function for cortical axons based on classic Hodgkin-Huxley (HH) neuronal equations and then apply the cable energy function to precisely estimate the energy consumption of AP conduction along axons with different geometric shapes. Our analytical approach predicts an inhomogeneous distribution of metabolic cost along an axon with either uniformly or nonuniformly distributed ion channels. The results show that the Na+-counting method severely underestimates energy cost in the cable model by 20–70%. AP propagation along axons that differ in length may require over 15% more energy per unit of axon area than that required by a point model. However, actual energy cost can vary greatly depending on axonal branching complexity, ion channel density distributions and AP conduction states. We also infer that the metabolic rate (i.e. energy consumption rate) of cortical axonal branches as a function of spatial volume exhibits a 3/4 power law relationship.
The Large Scale Synthesis of Aligned Plate Nanostructures
Authors: Zhou Yang , Nash Philip , Liu Tian , Zhao Naiqin , Zhu Shengli
Published: July 2016

We propose a novel technique for the large-scale synthesis of aligned-plate nanostructures that are self-assembled and self-supporting. The synthesis technique involves developing nanoscale two-phase microstructures through discontinuous precipitation followed by selective etching to remove one of the phases. The method may be applied to any alloy system in which the discontinuous precipitation transformation goes to completion. The resulting structure may have many applications in catalysis, filtering and thermal management depending on the phase selection and added functionality through chemical reaction with the retained phase. The synthesis technique is demonstrated using the discontinuous precipitation of a γ′ phase, (Ni, Co)3Al, followed by selective dissolution of the γ matrix phase. The production of the nanostructure requires heat treatments on the order of minutes and can be performed on a large scale making this synthesis technique of great economic potential.
Magnetic field effects in dye-sensitized solar cells controlled by different cell architecture
Authors: Klein M. , Pankiewicz R. , Zalas M. , Stampor W.
Published: July 2016

The charge recombination and exciton dissociation are generally recognized as the basic electronic processes limiting the efficiency of photovoltaic devices. In this work, we propose a detailed mechanism of photocurrent generation in dye-sensitized solar cells (DSSCs) examined by magnetic field effect (MFE) technique. Here we demonstrate that the magnitude of the MFE on photocurrent in DSSCs can be controlled by the radius and spin coherence time of electron-hole (e-h) pairs which are experimentally modified by the photoanode morphology (TiO2 nanoparticles or nanotubes) and the electronic orbital structure of various dye molecules (ruthenium N719, dinuclear ruthenium B1 and fully organic squaraine SQ2 dyes). The observed MFE is attributed to magnetic-field-induced spin-mixing of (e-h) pairs according to the Δg mechanism.
How will Somali coastal upwelling evolve under future warming scenarios?
Authors: deCastro M. , Sousa M. C. , Santos F. , Dias J. M. , Gómez-Gesteira M.
Published: July 2016

Somali upwelling system, the fifth in the world, presents some unique features compared with the other major upwelling systems: 1) it is a Western Boundary Upwelling System located near the Equator and 2) upwelling affects the moisture responsible for monsoon rainfall. The intensity of Somali coastal upwelling during summer was projected for the twenty first century by means of an ensemble of Global Climate Models and Regional Climate Models within the framework of CMIP5 and CORDEX projects, respectively. Regardless global or regional circulation models and the chosen greenhouse warming scenario, the strengthening of Somali coastal upwelling, which increases with latitude, is even higher than observed for the Eastern Boundary Upwelling System. In addition, coastal upwelling strengthening is mainly due to Ekman transport since Ekman pumping shows no clear trend for most of the latitudes. Projected land-sea air temperature and pressure show a clear intensification of land-sea thermal and pressure gradient as a consequence of the global warming, which is likely to affect the strengthening of Somali upwelling verifying the hypothesis of Bakun. As a consequence, projected sea surface temperature warming is less intense nearshore than at oceanic locations, especially at latitudes where upwelling strengthening is more intense.
Electronic absorption spectra of imidazolium-based ionic liquids studied by far-ultraviolet spectroscopy and quantum chemical calculations
Authors: Tanabe Ichiro , Kurawaki Yuji , Morisawa Yusuke , Ozaki Yukihiro
Published: July 2016

Electronic absorption spectra of imidazolium-based ionic liquids were studied by far- and deep-ultraviolet spectroscopy and quantum chemical calculations.
Improving the robustness of cobalt porphyrin water oxidation catalysts by chlorination of aryl groups
Authors: Nakazono Takashi , Sakai Ken
Published: July 2016

A chlorinated cobalt porphyrin (CoClPS) shows extremely high resistance against singlet oxygen and activity for photochemical water oxidation.
A novel 3D energetic MOF of high energy content: synthesis and superior explosive performance of a Pb(ii) compound with 5,5′-bistetrazole-1,1′-diolate
Authors: Shang Yu , Jin Bo , Peng Rufang , Liu Qiangqiang , Tan Bisheng , Guo Zhicheng , Zhao Jun , Zhang Qingchun
Published: July 2016

A novel 3D energetic metal–organic framework (MOF) of exceptionally high energy content, [Pb(BTO)(H2O)]n, was synthesized and structurally characterized by single crystal X-ray diffraction.
A strategically designed porous magnetic N-doped Fe/Fe3C@C matrix and its highly efficient uranium(vi) remediation
Authors: Wen Tao , Wang Xiangxue , Wang Jian , Chen Zhongshan , Li Jiaxing , Hu Jun , Hayat Tasawar , Alsaedi Ahmed , Grambow Bernd , Wang Xiangke
Published: July 2016

Magnetic N-doped Fe/Fe3C@C derived from metal–organic frameworks and highly efficient U(vi)-contaminated wastewater remediation.
Racemization barriers of atropisomeric 3,3′-bipyrroles: an experimental study with theoretical verification
Authors: Chatterjee Sourav , Butterfoss Glenn L. , Mandal Madhumita , Paul Bishwajit , Gupta Sreya , Bonneau Richard , Jaisankar Parasuraman
Published: July 2016

The activation barrier of racemization was determined for atropisomeric 3,3′-bipyrroles and they are found to be configurationally stable.
Three-dimensional carbon boron nitrides with a broken, hollow, spherical shell for water treatment
Authors: Jia Huichao , Li Jie , Liu Zhenya , Gao Ruoyuan , Abbas Saleem , Fang Yi , Yu Chao , Tang Chengchun
Published: July 2016

Broken hollow spherical shell like 3D C-BNs with a very fast dye adsorption rate for water purification.
Photolysis and photocatalytic decomposition of sulfamethazine antibiotics in an aqueous solution with TiO2
Authors: Tzeng Tai-Wei , Wang Shan-Li , Chen Chiing-Chang , Tan Chen-Chung , Liu Yu-Ting , Chen Tsan-Yao , Tzou Yu-Min , Chen C.C. , Hung J. T.
Published: July 2016

Photo-decomposition of sulfamethazine (SMT) involves photolytic and photo-catalytic reactions, which occur simultaneously.
Combined toxicity of Fe3O4 nanoparticles and cadmium chloride in mice
Authors: Zhang Yan , Xu Xiaolong , Zhu Shanshan , Song Jiajia , Yan Xincheng , Gao Shang
Published: July 2016

Co-exposure to nano-Fe3O4 and CdCl2 attenuated CdCl2-induced damage in mice through mutually competitive inhibition of Fe and Cd uptake.
NLRP3 inflammasome as a target of berberine in experimental murine liver injury: interference with P2X7 signalling
Authors: Vivoli Elisa , Cappon Andrea , Milani Stefano , Piombanti Benedetta , Provenzano Angela , Novo Erica , Masi Alessio , Navari Nadia , Narducci Roberto , Mannaioni Guido , Moneti Gloriano , Oliveira Claudia P. , Parola Maurizio , Marra Fabio
Published: July 2016

Berberine (BRB) is commonly used in herbal medicine, but its mechanisms of action are poorly understood. In the present study, we tested BRB in steatohepatitis induced by a methionine- and choline-deficient (MCD) diet, in acute acetaminophen intoxication and in cultured murine macrophages. BRB markedly improved parameters of liver injury and necroinflammation induced by the MCD diet, although increased mortality was observed by mechanisms independent of bacterial infections or plasma levels of BRB. The MCD diet induced up-regulation of all components of the NLRP3 (NACHT, LRR and PYD domain-containing protein 3) inflammasome, and increased hepatic levels of mature IL-1β (interleukin 1β). All of these parameters were significantly reduced in mice treated with BRB. In mice administered an acetaminophen overdose, a model dependent on inflammasome activation, BRB reduced mortality and ALT (alanine aminotransferase) elevation, and limited the expression of inflammasome components. In vitro, LPS (lipopolysaccharide)-induced activation of NLRP3 inflammasome in RAW264.7 murine macrophages was markedly decreased by pre-incubation with BRB. BRB significantly limited the activation of the purinergic receptor P2X7, involved in the late phases of inflammasome activation. Upon P2X7 knockdown, the ability of BRB to block LPS-induced secretion of IL-1β was lost. These data indicate that administration of BRB ameliorates inflammation and injury in two unrelated murine models of liver damage. We demonstrate for the first time that BRB interferes with activation of the NLRP3 inflammasome pathway in vivo and in vitro, through a mechanism based on interference with activation of P2X7, a purinergic receptor involved in inflammasome activation.
Coupling of an acoustic wave to shear motion due to viscous heating
Authors: Liu Bin , Goree J.
Published: July 2016

Viscous heating due to shear motion in a plasma can result in the excitation of a longitudinal acoustic wave, if the shear motion is modulated in time. The coupling mechanism is a thermal effect: time-dependent shear motion causes viscous heating, which leads to a rarefaction that can couple into a longitudinal wave, such as an acoustic wave. This coupling mechanism is demonstrated in an electrostatic three-dimensional (3D) simulation of a dusty plasma, in which a localized shear flow is initiated as a pulse, resulting in a delayed outward propagation of a longitudinal acoustic wave. This coupling effect can be profound in plasmas that exhibit localized viscous heating, such as the dusty plasma we simulated using parameters typical of the PK-4 experiment. We expect that a similar phenomenon can occur with other kinds of plasma waves.
Hydrogen-related complexes in Li-diffused ZnO single crystals
Authors: Corolewski Caleb D. , Parmar Narendra S. , Lynn Kelvin G. , McCluskey Matthew D.
Published: July 2016

Zinc oxide (ZnO) is a wide band gap semiconductor and a potential candidate for next generation white solid state lighting applications. In this work, hydrogen-related complexes in lithium diffused ZnO single crystals were studied. In addition to the well-known Li-OH complex, several other hydrogen defects were observed. When a mixture of Li2O and ZnO is used as the dopant source, zinc vacancies are suppressed and the bulk Li concentration is very high (>1019 cm−3). In that case, the predominant hydrogen complex has a vibrational frequency of 3677 cm−1, attributed to surface O-H species. When Li2CO3 is used, a structured blue luminescence band and O-H mode at 3327 cm−1 are observed at 10 K. These observations, along with positron annihilation measurements, suggest a zinc vacancy–hydrogen complex, with an acceptor level ∼0.3 eV above the valence-band maximum. This relatively shallow acceptor could be beneficial for p-type ZnO.
Thermal cloak-concentrator
Authors: Shen Xiangying , Li Ying , Jiang Chaoran , Ni Yushan , Huang Jiping
Published: July 2016

For macroscopically manipulating heat flow at will, thermal metamaterials have opened a practical way, which possesses a single function, such as either cloaking or concentrating the flow of heat even though environmental temperature varies. By developing a theory of transformation heat transfer for multiple functions, here we introduce the concept of intelligent thermal metamaterials with a dual function, which is in contrast to the existing thermal metamaterials with single functions. By assembling homogeneous isotropic materials and shape-memory alloys, we experimentally fabricate a kind of intelligent thermal metamaterials, which can automatically change from a cloak (or concentrator) to a concentrator (or cloak) when the environmental temperature changes. This work paves an efficient way for a controllable gradient of heat, and also provides guidance both for arbitrarily manipulating the flow of heat and for efficiently designing similar intelligent metamaterials in other fields.