bluuebunny/crossref_metadata_2025 huggingface dataset:
Optical Spectroscopy of V393 Scorpii During its Long Cycle
Authors: Mennickent Ronald E. , Kołaczkowski Zbigniew , Djurasevic Gojko , Diaz M. , Niemczura Ewa
Published: April 2012

V393 Scorpii is a bright Galactic Double Periodic Variable showing a long photometric cycle of ≈253 days. The ASAS V-band light curve has been disentangled into an orbital and long cycle component. The orbital light curve was modeled with two stellar components and a circumprimary accretion disk. Based on this model, and the careful choice of a template spectrum for the donor, the contribution of the donor to the line+continuum spectrum was removed at every orbital phase. The remaining residual spectra were analyzed. Notable findings are the larger line emissivity observed during the long cycle maximum that is concentrated to low velocities and the presence of discrete absorption components in the wings of the OI 7773 line, whose visibility strongly depends on the orbital phase. In addition, weak emission is observed in donor metallic absorption lines. Finally, we present the first Hα Doppler map for V 393 Scorpii. A modulated wind explains many observational features.
Advanced Tools for Exploring Large EB Datasets
Authors: Devinney E. J. , Pršsa A. , Guinan E. F. , Degeorge M.
Published: April 2012

Thanks to OGLE, Kepler, CoRoT and planned new ambitious survey projects, the eclipsing binary (EB) community is beginning to experience a long-predicted data deluge. Beyond the analysis of the many fascinating individual objects yielded by these programs, these complete datasets themselves should yield further insights. Because objects in such datasets are characterized by many parameters, tools that assist in understanding high-dimensional data are acquiring increasing relevance. Chiefly among these are new Advanced Visualization (AV) tools and various methods of clustering data, both approaches complementing each other naturally. We illustrate the use of these tools as applied to OGLE II LMC EB data and respective EBAI light curve solutions.
Physical Parameters of the Detached Eclipsing Binary KIC3858884 with a δ-Scuti Type Pulsating Component
Authors: Lee C.-U. , Kim S.-L. , Lee J. W. , Pavlovski K. , Southworth J.
Published: April 2012

We present physical parameters for the detached eclipsing binary KIC3858884 which has a δ-Scuti type pulsating secondary component. To derive orbital elements from the radial-velocity curve, high resolution Echelle spectra were obtained at the Bohyunsan Optical Astronomy Observatory in Korea. The BOES spectra and Kepler photometric data were analyzed with well-known codes: JKTEBOP and Wilson-Devinney model for eclipsing light-curve synthesis, and Period04 for pulsation frequency analysis. After the iterative curve fitting, we determined the physical parameters of KIC3858884 as M1=2.02 ± 0.23M⊙, M2=2.02 ± 0.16M⊙, R1=3.61 ± 0.12R⊙, R2=2.84 ± 0.10R⊙, respectively.
Mass and Orbit Constraints of the Gamma-ray Binary LS 5039
Authors: Szalai T. , Sarty G. E. , Kiss L. L. , Matthews J. M. , Vinkó J. , Kiss C.
Published: April 2012

We present the results of space-based photometric and ground-based spectroscopic observing campaigns on the γ-ray binary LS 5039. The new orbital and physical parameters of the system are similar to former results, except we found a lower eccentricity. Our MOST-data show that any broad-band optical photometric variability at the orbital period is below the 2 mmag level. Light curve simulations support the lower value of eccentricity and imply that the mass of the compact object is higher than 1.8 M⊙.
Towards an Increased Accuracy of Fundamental Properties of Stars: Proposing a Set of Nominal Astrophysical Parameters and Constants
Authors: Prša A. , Harmanec P.
Published: April 2012

With the precision of space-borne photometers better than 100 ppm (i.e. MOST, CoRoT and Kepler), the derived stellar properties often suffer from systematic offsets due to the values used for solar mass, radius and luminosity, and to fundamental astrophysical constants. Stellar parameters are often expressed in terms of L⊙, M⊙ and R⊙, but the actual values used vary from study to study. Here, we propose to adopt a nominal set of fundamental solar parameters that will impose consistency across published works and eliminate systematics that stem from inconsistent values. We further implore the community to rigorously use the official values of fundamental astrophysical constants set forth by the Committee on Data for Science and Technology (CODATA).
The Disentangling of Stellar Spectra
Authors: Hadrava P.
Published: April 2012

The techniques of disentangling were originally developed to separate spectra of individual components from time series of spectra of binaries and, simultaneously, to determine either the corresponding radial velocities or directly to solve for orbital parameters.

Generalizations of the disentangling method enable us to include also intrinsic line-profile variability of the component spectra into the underlying model, and thus to solve for additional physical parameters of the stars (either single or components of multiple systems). Depending on the problem in question, it may also be helpful to constrain the space of separated spectra by templates or to bound the solution in the parameter space by photometry, interferometry or other observational data.
The Rossiter-McLaughlin Effect for Planets and Low-Mass Binaries
Authors: Triaud Amaury H. M. J.
Published: April 2012

The Rossiter-McLaughlin effect occurs during the eclipse or transit of an object in front of another one. In our case, it appears as an anomaly on the radial velocity Doppler reflex motion. The modelling of that effect allows one to measure the sky-projected angle between the rotation spin of the primary and the orbital spin of the secondary. In the case of exoplanets, it gave clues about the formation of the hot Jupiters. In this paper, I will talk about how the data are acquired, how models are adjusted to them, and which results have been made.
Period Analyses Without O-C Diagrams
Authors: Mikulášek Zdeněk , Zejda Miloslav , Janík Jan
Published: April 2012

We present a versatile method appropriate for the period analyses of observations containing phase information of all kinds of periodic or nearly periodic variable stars on the basis of phenomenological modelling of their phase curves and phase functions. The approach is based on rigorous application of a non-linear weighted least-squares method exploiting all available observational data and does not need an O-C diagram as an intermediate stage for period analyses. However, this approach enables us to determine precise times of extrema of light curves, to calculate ephemerides and construct plausible O-C diagrams. We substantiate the general applicability of the method on eclipsing binaries research.
Non-Conservative Evolution of Binary Stars
Authors: Tout Christopher A.
Published: April 2012

Various processes can lead to non-conservative evolution in binary stars. Under conservative mass transfer, both the total mass and the orbital angular momentum of the system are conserved. Thus, the transfer of angular momentum between the orbit and the spins of the stars can represent one such effect. Stars generally lose mass and angular momentum in a stellar wind so, even with no interaction, evolution is non-conservative. Indeed, a strong wind can actually drive mass transfer. During Roche lobe overflow itself, mass transfer becomes non-conservative when the companion cannot accrete all the material transferred by the donor. In some cases, material is simply temporarily stored in an accretion disc. In others, the companion may swell up and initiate common envelope evolution. Often the transferred material carries enough angular momentum to spin the companion up to break-up, at which point it could not accrete more. We investigate how this is alleviated by non-conservative evolution.
Direct Imaging of Bridged Twin Protoplanetary Disks in a Young Multiple Star
Authors: Mayama Satoshi , Tamura Motohide , Hanawa Tomoyuki , Matsumoto Tomoaki , Ishii Miki , Pyo Tae-Soo , Suto Hiroshi , Naoi Takahiro , Kudo Tomoyuki , Hashimoto Jun , Nishiyama Shogo , Kuzuhara Masayuki , Hayashi Masahiko
Published: April 2012

Protoplanetary disks are ubiquitously observed around young solar-mass stars and are considered to be not only natural by-products of stellar evolution but also precursors of planet formation. If a forming star has close companions, the protoplanetary disk may be seriously influenced. It is important to consider this effect because most stars form as multiples. Thus, studies of protoplanetary disks in multiple systems are essential to describe the general processes of star and planet formation.

We present the direct image of an interacting binary protoplanetary system. We obtained an infrared image of a young multiple circumstellar disk system, SR24, with the Subaru 8.2-m Telescope. Both circumprimary and circumsecondary disks are clearly resolved with a 0.1 arcsecond resolution. The binary system exhibits a bridge of infrared emission connecting the two disks and a long spiral arm extending from the circumprimary disk. A spiral arm would suggest that the SR24 system rotates counter-clockwise. The orbital period of the binary is 15,000 yr. Numerical simulations reveal that the bridge corresponds to gas flow and a shock wave caused by the collision of gas rotating around the primary and secondary stars. The simulations also show that fresh material streams along the spiral arm, confirming the theoretical proposal that gas is replenished from a circum-multiple reservoir. These results reveal the mechanism of interacting protoplanetary disks in young multiple systems. Furthermore, our observations provide the first direct image that enables a comparison with theoretical models of mass accretion in binary systems. The observations of this binary system provide a great opportunity to test and refine theoretical models of star and planet formation in binary systems.
Formation and Orbital Evolution of Planets
Authors: Kley Wilhelm
Published: April 2012

The formation of planetary systems is a natural byproduct of the star formation process. Planets can form inside the protoplanetary disk by two alternative processes. Either through a sequence of sticking collisions, the so-called sequential accretion scenario, or via gravitational instability from an over-dense clump inside the protoplanetary disk. The first process is believed to have occurred in the solar system. The most important steps in this process will be outlined. The observed orbital properties of exoplanetary systems are distinctly different from our own Solar System. In particular, their small distance from the star, their high eccentricity and large mass point to the existence of a phase with strong mutual excitations. These are believed to be a result of early evolution of planets due to planet-disk interaction. The importance of this process in shaping the dynamical structure of planetary systems will be presented.
Eclipse Timing Variations of Planets in P-Type Binary Star Systems
Authors: Schwarz Richard , Haghighipour Nader , Funk Barbara , Eggl Siegfried , Pilat-Lohinger Elke
Published: April 2012

In close eclipsing binaries, measurements of the variations in the binary's eclipse timing may be used to infer information about the existence of planets in P-Type motion. To study the possibility of detecting such planets with CoRoT and Kepler, we calculated eclipse timing variations (ETV) for different values of the mass and orbital elements of the perturbing planet. These investigations are a continuation of the work of Schwarz et al. (2011).
New Insights into the Dynamics of Planets in P-Type Motion Around Binaries
Authors: Funk Barbara , Eggl Siegfried , Gyergyovits Markus , Schwarz Richard , Pilat-Lohinger Elke
Published: April 2012

Up to now, more than 500 extra-solar planets have been discovered. Many of these extrasolar systems consist of one star and only one giant planet. However, recently more and more different types of systems have become known, including also extrasolar planets in binaries. In our study, we will concentrate on such systems, since a large percentage of all G-M stars are expected to be part of binary or multiple stellar systems. Therefore, these kinds of systems are worthy of investigation in detail. In particular, we will concentrate on planets in P-Type motion, where the planet orbits around both stars. During the last few years, four such systems (NN Ser, HW Vir, HU Aqr and DP Leo) have been discovered. In our study, we performed dynamical studies for three multi-planetary systems in binaries (NN Ser, HW Vir, HU Aqr), and compared simulated eclipse timing variations (ETV) to current observational data.
The Evolution of Low Mass Contact Binaries
Authors: Stępień Kazimierz , Gazeas Kosmas
Published: April 2012

We discuss the origin and evolution of low mass contact binaries with Porb shorter than 0.3 d that have properties somewhat different from the rest of the contact binaries. A comparison of an evolutionary model set with observations shows that both components are on the main sequence, the age of the binaries is at least several Gyr, while the contact phase lasts only less than 1 Gyr.
Kinematic Properties of Chromospheric Active Binary Stars
Authors: Tüysüz M. , Soydugan F. , Bilir S. , Demircan O.
Published: April 2012

The kinematic behaviour of 362 chromospherically active binary stars (CABs) in the solar neighbourhood were investigated. The Third CABs Catalog by Eker et al. (2008) was used as the main source. The spatial distribution and the components of the Galactic space velocities of the programme stars were determined. The effects of differential rotation and Local Standard of Rest (LSR) were corrected for all systems.

Forty probable moving group (MG) members were determined by Eggen's criteria. The kinematic age of the young systems, which are probable members of MGs, was calculated as 0.79 (0.21) Gyr and the rest of 322 field stars were found to have a kinematic age of 4.38 (1.1) Gyr. Field CABs were separated into two sub-groups: dwarf systems, which were formed by main sequence (dwarf) stars, and evolved systems included at least one evolved (giant or sub-giant) component. The kinematic age of 134 dwarf systems was calculated as 4.69 (0.75) Gyr and 4.15 (1.29) Gyr for 188 evolved CABs.
Age Dependent Angular Momentum, Orbital Period and Total Mass of Detached Binaries
Authors: Demircan O. , Tüysüz M. , Soydugan F. , Bilir S.
Published: April 2012

The orbital angular momenta OAM (J) of detached binaries (including both cool and hot binaries) were estimated and nine subgroups were formed according to their OAM (J) distribution. The mean kinematical ages of all subgroups have been estimated by using their space velocity distributions and, thus, the age dependent variations of the mean OAM (J), orbital period (P), and total mass (M) of all subgroups were investigated. It was discovered that: i) The orbital period of detached binaries with radiative components decrease very slowly during the main sequence (MS) evolution. It is interesting that the large amount of mass loss is almost balanced by the OAM loss, and not much change in the orbital periods is observed. ii) The nuclear evolution of radiative components beyond the MS initiates the increase of the periods until the components have convective upper layers, i.e. until they become later than F5 IV, and the system becomes a cool binary with sub-giant or giant components. iii) The large co-rotating distance of the magnetically-driven wind in cool binaries (CAB) carries out a large amount of OAM and then the periods of such binaries decrease significantly, and the orbits shrink until another effect such as mass transfer dominates the period changes.
Li and Be Depletion in Stars with Exoplanets?
Authors: Delgado Mena E. , Israelian G. , González Hernández J. I. , Rebolo R. , Santos N. C. , Sousa S. G. , Fernandes J.
Published: April 2012

It is well known that stars with orbiting giant planets have a higher metallic content than stars without detected planets. In addition, we have found that solar-type stars with planets present an extra Li depletion when compared with field stars. On the other hand, Be needs a greater temperature to be destroyed, so we may find such a relation in cooler stars, whose convective envelopes are deep enough to carry material to layers where Be can be burned. We present Li and Be abundances for an extensive sample of stars with and without detected planets, covering a wide range of effective temperatures (4700-6500 K) with the aim of studying possible differences between the abundances of both groups. The processes that take place in the formation of planetary systems may affect the mixing of material inside their host stars and hence the abundances of light elements.
Binary Systems As Gravitational Wave Sources
Authors: Köse O. , Yakut K.
Published: April 2012

Binary systems with compact components and some newly discovered systems with relatively short orbital periods are studied as gravitational-wave sources. The gravitational wave amplitudes of these systems have been compared with the limit of gravitational wave interferometers (e.g. LISA, LIGO, and VIRGO).
The Keck I/HIRES and TNG/SARG Radial Velocity Survey of Speckle Binaries
Authors: Ratajczak Milena , Konacki Maciej , Kulkarni Shrinivas R. , Muterspaugh Matthew W.
Published: April 2012

A sample of about 160 speckle binary stars was observed with the Keck I telescope and its Échelle HIRES spectrograph over the years 2003-2007 in an effort to detect substellar and planetary companions to components of binary and multiple star systems. This data set was supplemented with the data obtained at the TNG telescope equipped with the SARG Échelle spectrograph over the years 2006-2007. The high-resolution (R = 65000 for HIRES and R = 86000 for SARG) and high signal-to-noise (typically 75-150) spectra were used to derive radial velocities of the components of the observed speckle binaries. Here, we present a summary of this effort, which includes the discovery of new triple star systems and improved orbital solutions of a few known binaries.
First Catalogue of Optically Variable Sources Observed by OMC Onboard INTEGRAL
Authors: Alfonso-Garzón Julia , Domingo Albert , Miguel Mas-Hesse José
Published: April 2012

In this work, we present the first catalogue of optically variable sources observed by the Optical Monitoring Camera (OMC), with information about the variability of more than 5000 objects and periodicity of ~ 1000 sources.
Day-Night Side Cooling of a Strongly Irradiated Giant Planet
Authors: Budaj Ján , Burrows Adam , Hubeny Ivan
Published: April 2012

The internal heat loss or cooling of a planet determines its structure and evolution. We address in a consistent fashion the coupling between the day and the night sides by means of model atmosphere calculations with heat redistribution. We assume that a strong convection leads to the same entropy on the day and night side and that the gravity is the same on both hemispheres. We argue that the core cooling rate from the two hemispheres of a strongly irradiated planet may not be the same and that the difference depends on several important parameters. If the day-night heat redistribution is very effective, or if it takes place at a large optical depth, then the day-side and the night-side cooling may be comparable. However, if the day-night heat transport is not effective, or if it takes place at a shallow optical depth, then there can be a big difference between the day-side and the night-side cooling and the night side may cool more effectively. If the stellar irradiation gets stronger e.g. due to the stellar evolution or migration, this will reduce both the day and the night side cooling. Enhanced metallicity in the atmosphere acts as a “blanket” and reduces both the day- and the night-side cooling. However, the stratosphere on the day side of the planet can enhance the day-side cooling since its opacity acts as a “shield” which screens the stellar irradiation. These results might affect the well known gravity darkening and bolometric albedo effects in interacting binaries, especially for strongly irradiated cold objects.
Surface Brightness Variation of the Contact Binary SW Lac: Clues From Doppler Imaging
Authors: Şenavcı Hakan Volkan
Published: April 2012

In this study, we present the preliminary light curve analysis of the contact binary SW Lac, using B, V light curves of the system spanning 2 years (2009 - 2010). During the spot modeling process, we used the information coming from the Doppler maps of the system, which was performed using the high resolution and phase dependent spectra obtained at the 2.1m Otto Struve Telescope of the McDonald Observatory, in 2009. The results showed that the spot modeling from the light curve analysis are in accordance with the Doppler maps, while the non-circular spot modeling technique is needed in order to obtain much better and reliable spot models.
Panel Discussion III
Authors: Allard F. , Batten A. , Budding E. , Devinney E. , Eggleton P. , Hatzes A. , Hubeny I. , Kley W. , Lammer H. , Linnell A. , Trimble V. , Wilson R. E.
Published: April 2012

I. Hubeny Does anyone from the panel have a theme question to start with today?

V. Trimble It's another one-liner: From an active galaxy meeting many years ago when people talked about spiral structure. I was reminded by Dr. Rucinski's talk of Lodewijk Woltjer's remark: “The larger our ignorance, the stronger the magnetic field.”
Flow Structure in Magnetic CVs
Authors: Bisikalo Dmitry V. , Zhilkin Andrey G.
Published: April 2012

We present a review of the modern concept of physical processes which go on in magnetic CVs with the mass transfer between the components. Using results of 3D MHD simulations, we investigated variations of the main characteristics of accretion disks depending on the value of the magnetic induction on the surface of the accreting star. In the frame of a self-consistent description of the MHD flow structure in close binaries, we formulate conditions of the disk formation and find a criterion that separates two types of flows corresponding to intermediate polars (intermediate magnetic field) and polars (strong field).

The influence of asynchronous rotation of the accretor on the flow structure in magnetic close binaries is also discussed. Simulations show that the accretion instability arising in binaries with rapid rotation of accretor (“propeller” regime) can explain the mechanism of quasi-periodic dwarf nova outbursts observed in DQ Her systems.
How Common Envelope Interactions Change the Lives of Stars and Planets
Authors: De Marco O. , Passy J.-C. , Herwig F. , Fryer C. L. , Mac Low M.-M. , Oishi J. S.
Published: April 2012

The common envelope interaction between a giant star and a stellar or substellar companion is at the origin of several compact binary classes, including the progenitors of Type Ia SN. A common envelope is also what will happen when the Sun expands and swallows its planets as far out as Jupiter. The basic idea and physics of the common envelope interaction has been known since the 1970s. However, the outcome of a common envelope interaction - what systems survive and what their parameters are - depends sensitively on the details of the engagement. To advance our knowledge of the common envelope interaction between stars and their stellar and substellar companions, we have carried out a series of simulations with Eulerian, grid-based and Lagrangian, smoothed particle hydrodynamics codes between a 0.88-M⊙, 85-R⊙, red giant branch star and companions in the mass range 0.1-0.9 M⊙. In this contribution, we will discuss the reliability of the techniques, the physics that is not included in the codes but is likely important, the state of the ejected common envelope, and the final binary separation. We also carry out a comparison with the observations. Finally, we discuss the common envelope efficiency parameter, α and the survival of planets.
Dynamical Stability and Habitability of Extra-Solar Planets
Authors: Pilat-Lohinger Elke
Published: April 2012

Observations of about 60 binary star systems hosting exoplanets indicate the necessity of stability studies of planetary motion in such multi-stellar systems. For wide binary systems with separations between hundreds and thousands of AU, the results from single-star systems may be applicable but, in tight double stars systems, we have to take the stellar interactions into account which influences the planetary motion significantly.

This review discusses the different types of planetary motion in double stars and the stability of the planets for different binary configurations. An application to the most famous tight binary system (γ Cephei) is also shown. Finally, we analyze the habitability from the dynamical point of view in such systems, where we discuss the motion of terrestrial-like planets in the so-called habitable zone.
Summary of Theoretical Techniques
Authors: Burrows Adam
Published: April 2012

In this summary, I address the next generation of theoretical tools with which it may be necessary to interpret the data anticipated as both stellar and planetary astronomy enter their next decades.
Global Environmental Constitutionalism: Getting There from Here
Authors: Kysar Douglas A.
Published: April 2012

Dominant analytical approaches to environmental law exhibit a similar, problematic form: they treat that which should be outcome determining as, instead, outcome determined. This form is most evident and influential in the welfare economic technique of regulatory cost–benefit analysis, which treats all resources – including the monetary value of human lives – as potential means towards seemingly higher yielding ends. In contrast, an environmental constitutionalism, in which certain needs and interests of present and future generations, the global community, and other forms of life are given foundational legal importance, would help to restore conceptual coherence and normative priority to the subjects of environmental law.
Look at Mother Nature on the Run in the 21stCentury: Responsibility, Research and Innovation
Authors: Lee Robert G.
Published: April 2012

There is growing interest in a framework for responsible research and innovation within Europe. This paper explores why this has come about and suggests that it is related to a concern with emerging and converging technologies that goes beyond a narrow conception of risk to the environment or to human health. Rather, there is a trepidation arising out of the transformative capacity of modern technologies and their stated aspiration to manipulate the natural world. In this context, the paper poses three central questions about the shape of any framework for responsible research and innovation. First, why is the target that of research and innovation? Secondly, at what scale should the framework operate? Thirdly, what form of governance structure would be best suited to the oversight of research and innovation?
“Hidden” threats to science education
Authors: Huntoon J. E. , Buchanan R. , Buhr S. M. , Kirst S. , Newton S. , Van Norden W.
Published: April 2012

Many readers of Eos are involved with education. Most would agree that what happens at precollege levels will ultimately affect the geoscience profession; after all, future scientists are today's precollege students. While a growing number of scientists are working to improve the quality of precollege programs, only a few are addressing what we term the “hidden” threats to science education. Hidden threats have nothing to do with scientific content; rather, they result from social, political, and bureaucratic forces operating within and outside of schools and universities.
Mechanical and field studies of deformation localization in rocks
Authors: Chemenda Alexandre , Petit Jean‐Pierre
Published: April 2012

Refining Constitutive Characterization of Geomaterials and Identifying Their Rupture Mechanisms in Natural Conditions; Montpellier, France, 7–8 September 2011 Results from rock testing and geological observations of different types of deformation bands and fractures highlight the problem of understanding the underlying formation mechanisms from granular (micro) to outcrop scale. Particularly puzzling are recently discovered compaction and dilatancy bands that are completely antipodal features. Both are narrow (several grain diameters thick), generally not planar but rather irregular and zigzagging (depending on the observation scale) bands that can form in the uniformly stressed rocks. The difference between them is that the compaction bands form at a relatively high pressure (mean stress) normal to the maximal compressive stress. The material within the compaction bands undergoes volume reduction due to the more dense grain packing and/ or crushing. Conversely, the dilatancy bands form at low pressure and normal to the least compressive stress. The material within them undergoes a volume increase due to grain rearrangements and/or formation of intragranular and intergranular microfractures. The dilatancy bands can become opened fractures with further deformation.
Nominations sought for inaugural Gilbert F. White Lecture
Authors: Williams Danica
Published: April 2012

Nominations for the first Gilbert F. White Distinguished Lecture Award, sponsored by AGU's Natural Hazards Focus Group, are due 1 May. The lecture, established last year, will be given during the 2012 AGU Fall Meeting in San Francisco, 3–7 December. The lecture is named for Gilbert F. White (1911–2006), an AGU Fellow who was internationally known for his significant contributions to natural hazards research. Some of White's most notable work involved the identification and classification of adjustment mechanisms for flooding in the United States, perceptions of natural hazards, and the importance of sound water management in contemporary society. White advocated, where feasible, adaptation to or accommodation of food hazards rather than the “structural” solutions (e.g., dams, levees, and foodwalls) that dominated policy in the early twentieth century
Deep‐sea sediments
Authors: Mekik Figen
Published: April 2012

Often unnoticed by the casual observer, every second of every day the oceans record the passing of time and the interaction of ocean, land, and atmosphere, grain after grain, precipitate after precipitate. Deep marine sediments serve as archives recording the history of ocean basins and lend insights into the rates and magnitudes of climatic and environmental change. As such, a collection of articles on recent cutting‐edge research summarizing various marine environments and processes is important and necessary for any Earth scientist. Such a compilation is particularly important for undergraduate and graduate audiences as well as educators charged with teaching them.
North American rivers a sizable source of atmospheric carbon
Authors: Schultz Colin
Published: April 2012

To fulfill the need for an ever more granular, accurate, and complete understanding of the flow of carbon through the Earth system, a flurry of research has taken place in the past decade on previously overlooked aspects of the carbon cycle. Researchers have investigated the roles of rivers, lakes, and streams in transporting carbon, often with mixed, or only broadly constrained, results. Further, many investigations have traditionally focused on a small number of sites. Although such focused measurements are important for pinning down spatial and temporal changes in the local exchange of carbon, they make expanding the results to broader regions difficult.
El Niño related to changes in sardine spawning
Authors: Balcerak Ernie
Published: April 2012

The Pacific sardine, an important species for commercial fishing, spawns off the coast of California. The area and quality of its spawning habitat have been observed to vary from year to year, sometimes changing with El Niño–Southern Oscillation conditions, but smaller‐scale mechanisms also play a role. To sort out the physical forcing mechanisms affecting sardine spawning, Song et al. used data assimilation, combining observational data on sea surface height, sea surface temperature, and salinity data with a physical ocean model. They then looked at how the physical mechanics could explain observed interannual variations in sardine spawning range and egg density
Thermokarst lakes increased atmospheric methane levels
Authors: Balcerak Ernie
Published: April 2012

Ice cores taken from Greenland indicate that during the last deglaciation, approximately 10,000 years ago, increases in temperature occurred at the same times as increases in atmospheric methane, a potent greenhouse gas. The source of the increase in atmospheric methane is still debated, but it has been suggested that thermokarst lakes, which form from thawing permafrost, contributed to the increased atmospheric methane. By establishing pathways of regionally varying hydrogen isotopes found in permafrost ground ice to methane produced in thermokarst lakes, Brosius et al. reconciled bottom‐up estimates of emission of methane from thermokarst lakes in various Arctic regions with isotope constraints from ice core records; they show that thermokarst lakes were indeed an important source of atmospheric methane during the deglacial period. (Journal of Geophysical Research‐Biogeosciences, doi:10.1029/2011JG001810, 2012)
Non‐thermal escape of molecular hydrogen from Mars
Authors: Gacesa M. , Zhang P. , Kharchenko V.
Published: April 2012

We present a detailed theoretical analysis of non‐thermal escape of molecular hydrogen from Mars induced by collisions with hot atomic oxygen from the Martian corona. To accurately describe the energy transfer in O + H2(v, j) collisions, we performed extensive quantum‐mechanical calculations of state‐to‐state elastic, inelastic, and reactive cross sections. The escape flux of H2molecules was evaluated using a simplified 1D column model of the Martian atmosphere with realistic densities of atmospheric gases and hot oxygen production rates for low solar activity conditions. An average intensity of the non‐thermal escape flux of H2 of 1.9 × 105 cm−2s−1 was obtained considering energetic O atoms produced in dissociative recombinations of O2+ions. Predicted ro‐vibrational distribution of the escaping H2was found to contain a significant fraction of higher rotational states. While the non‐thermal escape rate was found to be lower than Jeans rate for H2molecules, the non‐thermal escape rates of HD and D2 are significantly higher than their respective Jeans rates. The accurate evaluation of the collisional escape flux of H2and its isotopes is important for understanding non‐thermal escape of molecules from Mars, as well as for the formation of hot H2 Martian corona. The described molecular ejection mechanism is general and expected to contribute to atmospheric escape of H2 and other light molecules from planets, satellites, and exoplanetary bodies.
The Wind Imaging Interferometer (WINDII) on the Upper Atmosphere Research Satellite: A 20 year perspective
Authors: Shepherd G. G. , Thuillier G. , Cho Y.‐M. , Duboin M.‐L. , Evans W. F. J. , Gault W. A. , Hersom C. , Kendall D. J. W. , Lathuillère C. , Lowe R. P. , McDade I. C. , Rochon Y. J. , Shepherd M. G. , Solheim B. H. , Wang D.‐Y. , Ward W. E.
Published: April 2012

The Wind Imaging Interferometer (WINDII) was launched on the NASA's Upper Atmosphere Research Satellite on 12 September 1991 and operated until 2003. Its role in the mission was to measure vector winds in the Earth's atmosphere from 80 to 110 km, but its measurements extended to nearly 300 km. The approach employed was to measure Doppler shifts from a suite of visible region airglow lines emitted over this altitude range. These included atomic oxygen O(1S) and O(1D) lines, as well as lines in the OH Meinel (8,3) and O2 Atmospheric (0,0) bands. The instrument employed was a Doppler Michelson Interferometer that measured the Doppler shift as a phase shift of the cosinusoidal interferogram generated by single airglow lines. An extensive validation program was conducted after launch to confirm the accuracy of the measurements. The dominant wind field, the first one observed by WINDII, was that of the migrating diurnal tide at the equator. The overall most notable WINDII contribution followed from this: determining the influence of dynamics on the transport of atmospheric species. Currently, nonmigrating tides are being studied in the thermosphere at both equatorial and high latitudes. Other aspects investigated included solar and geomagnetic influences, temperatures from atmospheric‐scale heights, nitric oxide concentrations, and the occurrence of polar mesospheric clouds. The results of these observations are reviewed from a perspective of 20 years. A future perspective is then projected, involving more recently developed concepts. It is intended that this description will be helpful for those planning future missions.
Body Composition at 6 months of Life: Comparison Of Air Displacement Plethysmography and Dual‐Energy X‐Ray Absorptiometry
Authors: Fields David A. , Demerath Ellen W. , Pietrobelli Angelo , Chandler‐Laney Paula C.
Published: April 2012

Body composition assessment during infancy is important because it is a critical period for obesity risk development, thus valid tools are needed to accurately, precisely, and quickly determine both fat and fat‐free mass. The purpose of this study was to compare body composition estimates using dual‐energy x‐ray absorptiometry (DXA) and air displacement plethysmography (ADP) at 6 months old. We assessed the agreement between whole body composition using DXA and ADP in 84 full‐term average‐for‐gestational‐age boys and girls using DXA (Lunar iDXA v11–30.062; Infant whole body analysis enCore 2007 software, GE, Fairfield, CT) and ADP (Infant Body Composition System v3.1.0, COSMED USA, Concord, CA). Although the correlations between DXA and ADP for %fat (r = 0.925), absolute fat mass (r = 0.969), and absolute fat‐free mass (r = 0.945) were all significant, body composition estimates by DXA were greater for both %fat (31.1 ± 3.6% vs. 26.7 ± 4.7%; P < 0.001) and absolute fat mass (2,284 ± 449 vs. 1,921 ± 492 g; P < 0.001), and lower for fat‐free mass (5,022 ± 532 vs. 5,188 ± 508 g; P < 0.001) vs. ADP. Inter‐method differences in %fat decreased with increasing adiposity and differences in fat‐free mass decreased with increasing infant age. Estimates of body composition determined by DXA and ADP at 6 months of age were highly correlated, but did differ significantly. Additional work is required to identify the technical basis for these rather large inter‐method differences in infant body composition.
Towards the prediction of order parameters from molecular dynamics simulations in proteins
Authors: Perilla Juan R. , Woolf Thomas B.
Published: April 2012

A molecular understanding of how protein function is related to protein structure requires an ability to understand large conformational changes between multiple states. Unfortunately these states are often separated by high free energy barriers and within a complex energy landscape. This makes it very difficult to reliably connect, for example by all-atom molecular dynamics calculations, the states, their energies, and the pathways between them. A major issue needed to improve sampling on the intermediate states is an order parameter – a reduced descriptor for the major subset of degrees of freedom – that can be used to aid sampling for the large conformational change. We present a method to combine information from molecular dynamics using non-linear time series and dimensionality reduction, in order to quantitatively determine an order parameter connecting two large-scale conformationally distinct protein states. This new method suggests an implementation for molecular dynamics calculations that may be used to enhance sampling of intermediate states.
Novel exposure system using light-emitting diodes and an optical fiber array for printing serial numbers and code marks
Authors: Iwasaki J. , Horiuchi T.
Published: April 2012

Feasibility of a novel exposure system to print serial numbers and two-dimensional code marks was demonstrated. The new system used light-emitting diodes (LEDs) combined with an optical fiber matrix array as a light source. At first, as preparatory experiments, code mark patterns were printed using a prototype exposure system without using the optical fiber array but using the combination of arrayed LEDs with a central wavelength of 428 nm, spherical lenses, and rod lenses. Although the code mark patterns were successfully printed, it took too much exposure time. For this reason, bullet-type LEDs with a high power and a shorter wavelength of 405 nm were used and the optical fiber matrix array was adopted. Because the emitted light rays were efficiently taken into the fiber, and the resist sensitivity was improved, practically available short exposure time of less than 2 s was obtained.
A scattering model for nano-textured interfaces and its application in opto-electrical simulations of thin-film silicon solar cells
Authors: Jäger K. , Fischer M. , van Swaaij R. A. C. M. M. , Zeman M.
Published: April 2012

We present a scattering model based on the scalar scattering theory that allows estimating far field scattering properties in both transmission and reflection for nano-textured interfaces. We first discuss the theoretical formulation of the scattering model and validate it for nano-textures with different morphologies. Second, we combine the scattering model with the opto-electric asa simulation software and evaluate this combination by simulating and measuring the external parameters and the external quantum efficiency of solar cells with different interface morphologies. This validation shows that the scattering model is able to predict the influence of nano-textured interfaces on the solar cell performance. The scattering model presented in this manuscript can support designing nano-textured interfaces with optimized morphologies.
Photovoltaic properties of the p-CuO/n-Si heterojunction prepared through reactive magnetron sputtering
Authors: Gao Fei , Liu Xiao-Jing , Zhang Jun-Shan , Song Mei-Zhou , Li Ning
Published: April 2012

Films of p-CuO were deposited on glass and n-Si substrates through reactive magnetron sputtering. The influence of flow rate ratio of O2 to Ar on the structural and electrical properties of the CuO films was studied. By increasing the flow rate ratio, the hole concentration of the CuO films decreased while the mobility and resistivity increase. At a flow rate ratio of 0.5, the average crystal size, hole concentration, mobility, resistivity, and optical bandgap of the deposited p-CuO films are ∼8 nm, 2.76×1015 cm−3, 0.134 cm2/Vs, 0.217 Ωcm, and 1.07 eV, respectively. A p-CuO film/n-Si substrate heterojunction cell has been fabricated and has an open-circuit voltage of 0.33 V and short-circuit current density of 6.27 mA/cm2 under AM 1.5D illumination. The fill factor and energy conversion efficiency are 0.2 and 0.41%, respectively.
Ligand migration in myoglobin: A combined study of computer simulation and x-ray crystallography
Authors: Tsuduki Takayuki , Tomita Ayana , Koshihara Shin-ya , Adachi Shin-ichi , Yamato Takahisa
Published: April 2012

A ligand-migration mechanism of myoglobin was studied by a multidisciplinary approach that used x-ray crystallography and molecular dynamics simulation. The former revealed the structural changes of the protein along with the ligand migration, and the latter provided the statistical ensemble of protein conformations around the thermal average. We developed a novel computational method, homogeneous ensemble displacement, and generated the conformational ensemble of ligand-detached species from that of ligand-bound species. The thermally averaged ligand-protein interaction was illustrated in terms of the potential of mean force. Although the structural changes were small, the presence of the ligand molecule in the protein matrix significantly affected the 3D scalar field of the potential of mean force, in accordance with the self-opening model proposed in the previous x-ray study.
Relaxation dynamics of ionic liquid—VO2 interfaces and influence in electric double-layer transistors
Authors: Zhou You , Ramanathan Shriram
Published: April 2012

Oxide semiconductor systems are often electrostatically doped with ionic liquids as gate insulators towards modulating carrier density and inducing phase transitions, while simultaneously serving as a means to probe their electronic phase diagram. The electronic and electrochemical properties of ionic liquid/correlated oxide interfaces are, therefore, important in interpreting such field-effect phenomena. Here, we use DEME-TFSI and VO2 as a model system to investigate the interface properties, slow relaxations, as well as field-effect in electric double layer transistor geometry. The stability of these interfaces is probed by combination of current-voltage measurements, x-ray photoelectron spectroscopy, impedance spectroscopy, and constant current charging. Three-terminal field effect transistor-type devices fabricated by photolithography are used to investigate kinetics of channel resistance modulations under varying gate bias polarity. Bias regions for reversible modulation of channel conductance have been determined. A time-dependent transconductance effect and as large as 20× increase in conductance are observed.
High electronegativity multi-dipolar electron cyclotron resonance plasma source for etching by negative ions
Authors: Stamate E. , Draghici M.
Published: April 2012

A large area plasma source based on 12 multi-dipolar ECR plasma cells arranged in a 3 × 4 matrix configuration was built and optimized for silicon etching by negative ions. The density ratio of negative ions to electrons has exceeded 300 in Ar/SF6 gas mixture when a magnetic filter was used to reduce the electron temperature to about 1.2 eV. Mass spectrometry and electrostatic probe were used for plasma diagnostics. The new source is free of density jumps and instabilities and shows a very good stability for plasma potential, and the dominant negative ion species is F−. The magnetic field in plasma volume is negligible and there is no contamination by filaments. The etching rate by negative ions measured in Ar/SF6/O2 mixtures was almost similar with that by positive ions reaching 700 nm/min.
New accurate reference energies for the G2/97 test set
Authors: Haunschild Robin , Klopper Wim
Published: April 2012

A recently proposed computational protocol is employed to obtain highly accurate atomization energies for the full G2/97 test set, which consists of 148 diverse molecules. This computational protocol is based on the explicitly correlated coupled-cluster method with iterative single and double excitations as well as perturbative triple excitations, using quadruple-ζ basis sets. Corrections for higher excitations and core/core-valence correlation effects are accounted for in separate calculations. In this manner, suitable reference values are obtained with a mean deviation of −0.75 kJ/mol and a standard deviation of 1.06 kJ/mol with respect to the active thermochemical tables. Often, in the literature, new approximate methods (e.g., in the area of density functional theory) are compared to, or fitted to, experimental heats of formation of the G2/97 test set. We propose to use our atomization energies for this purpose because they are more accurate on average.
Relative importance of mega electronvolt-electron energy deposition by collisions and field effects in fast ignition
Authors: Cao Lihua , Chen Mo , He X. T. , Yu Wei , Yu M. Y.
Published: April 2012

The rates of energy deposition of MeV electrons by return-current Ohmic heating and Coulomb collisions are compared in the context of the fast ignition scheme of inertial confinement fusion. A criterion for distinguishing the relative importance of the two heating mechanisms is presented. It depends on the kinetic energy of the relativistic electrons, the temperature of the background plasma, as well as the ratio between the densities of the two groups of electrons. A critical density ratio is also found.