bluuebunny/crossref_metadata_2025 huggingface dataset:
Mirror representations innate versus determined by experience: A viewpoint from learning theory
Authors: Giese Martin A.
Published: April 2014

From the viewpoint of pattern recognition and computational learning, mirror neurons form an interesting multimodal representation that links action perception and planning. While it seems unlikely that all details of such representations are specified by the genetic code, robust learning of such complex representations likely requires an appropriate interplay between plasticity, generalization, and anatomical constraints of the underlying neural architecture.
Higher-level processes in the formation and application of associations during action understanding
Authors: Heil Lieke , van Pelt Stan , Kwisthout Johan , van Rooij Iris , Bekkering Harold
Published: April 2014

The associative account described in the target article provides a viable explanation for the origin of mirror neurons. We argue here that if mirror neurons develop purely by associative learning, then they cannot by themselves explain intentional action understanding. Higher-level processes seem to be involved in the formation of associations as well as in their application during action understanding.
Associative and sensorimotor learning for parenting involves mirror neurons under the influence of oxytocin
Authors: Ho S. Shaun , MacDonald Adam , Swain James E.
Published: April 2014

Mirror neuron–based associative learning may be understood according to associative learning theories, in addition to sensorimotor learning theories. This is important for a comprehensive understanding of the role of mirror neurons and related hormone modulators, such as oxytocin, in complex social interactions such as among parent–infant dyads and in examples of mirror neuron function that involve abnormal motor systems such as depression.
Reconciling genetic evolution and the associative learning account of mirror neurons through data-acquisition mechanisms
Authors: Lotem Arnon , Kolodny Oren
Published: April 2014

An associative learning account of mirror neurons should not preclude genetic evolution of its underlying mechanisms. On the contrary, an associative learning framework for cognitive development should seek heritable variation in the learning rules and in the data-acquisition mechanisms that construct associative networks, demonstrating how small genetic modifications of associative elements can give rise to the evolution of complex cognition.
Vocal coordination and vocal imitation: A role for mirror neurons?
Authors: Newman John D.
Published: April 2014

Some birds and mammals have vocal communication systems in which coordination between individuals is important. Examples would include duetting or antiphonal calling in some birds and mammals, rapid exchanges of the same vocalization, and vocal exchanges between paired individuals and other nearby pairs. Mirror neurons may play a role in such systems but become functional only after experience.
Contagious behavior: An alternative approach to mirror-like phenomena
Authors: Provine Robert R.
Published: April 2014

Contagious behaviors such as yawning and itching/scratching have mirror-like properties and clearly defined stimulus and motor parameters; they are also relatively easy to study and should be part of the debate about mirror neurons and the neurological mechanisms of social behavior. The broadly tuned, multimodal stimuli of contagious behavior challenge present accounts of mirror mechanisms that focus on specific, mirrored acts.
Confounding the origin and function of mirror neurons
Authors: Rizzolatti Giacomo
Published: April 2014

Cook et al. argue that mirror neurons originate in sensorimotor associative learning and that their function is determined by their origin. Both these claims are hard to accept. It is here suggested that a major role in the origin of the mirror mechanism is played by top-down connections rather than by associative learning.
Image-based robotic control with unknown camera parameters and joint velocities
Authors: Hua Changchun , Liu Yinjuan , Yang Yana
Published: April 2014

A new image-based controller is proposed for the robotic system with the joint velocity signals unavailable. The Immersion and Invariance (I&I) observer is applied to estimate the unknown velocity information. Compared with the general velocity observer, the I&I observer can estimate the unknown velocity exponentially. We consider the case that the exact camera parameters are not known. The corresponding adaptive controller is designed for the robot system and the stability is rigorously proven by using Lyapunov theorem. Finally, simulations are performed and the results show the effectiveness of the proposed control approach.
ETHICS EXPERTISE FOR HEALTH TECHNOLOGY ASSESSMENT: A CANADIAN NATIONAL SURVEY
Authors: Bond Kenneth , Oremus Mark , Duthie Katherine M. , Griener Glenn G.
Published: April 2014

Objectives: The aim of this study was to identify individuals with expertise in ethics analysis in Canada, who might contribute to health technology assessment (HTA); to gauge these individuals’ familiarity with, and experience participating in, the production of HTA.

Methods: A contact list was developed using the Canadian Bioethics Society membership list and faculty listings of Canadian universities, bioethics centers, and health agencies. An eighteen-question email survey was distributed to potential respondents to collect data on demographic information, education and work experience in applied ethics, and involvement in HTA.

Results: The survey response rate was 52.8 percent (350/663). Respondents worked primarily in academic institutions (50.4 percent) or hospitals (15.4 percent). Many respondents (83.1 percent) had education, formal training, or work-related experience in practical ethics related to health care, with many having a doctorate (34.5 percent) or master's degree (19.0 percent). One quarter (24.5 percent; n = 87) of respondents indicated they had been involved in an analysis of ethical issues for HTA. Almost two-thirds (65.4 percent; n = 165) of those who had not previously participated in ethics analysis believed they might usefully contribute to an analysis of ethical issues in HTA. Experts who have conducted ethics analysis in HTA had more than twice the odds of having education and training in ethics and a PhD than those who might contribute to ethics analysis.

Conclusion: Many people have contributed to ethics analysis in HTA in Canada, and more are willing to do so. Given the absence of a reliable credential for ethics expertise, HTA producers should exercise caution when enlisting ethics experts.
BOOTSTRAPPING DENSITY-WEIGHTED AVERAGE DERIVATIVES
Authors: Cattaneo Matias D. , Crump Richard K. , Jansson Michael
Published: April 2014

We investigate the properties of several bootstrap-based inference procedures for semiparametric density-weighted average derivatives. The key innovation in this paper is to employ an alternative asymptotic framework to assess the properties of these inference procedures. This theoretical approach is conceptually distinct from the traditional approach (based on asymptotic linearity of the estimator and Edgeworth expansions), and leads to different theoretical prescriptions for bootstrap-based semiparametric inference. First, we show that the conventional bootstrap-based approximations to the distribution of the estimator and its classical studentized version are both invalid in general. This result shows a fundamental lack of “robustness” of the associated, classical bootstrap-based inference procedures with respect to the bandwidth choice. Second, we present a new bootstrap-based inference procedure for density-weighted average derivatives that is more “robust” to perturbations of the bandwidth choice, and hence exhibits demonstrable superior theoretical statistical properties over the traditional bootstrap-based inference procedures. Finally, we also examine the validity and invalidity of related bootstrap-based inference procedures and discuss additional results that may be of independent interest. Some simulation evidence is also presented.
From Administrative Infrastructure to Biomedical Resource: Danish Population Registries, the “Scandinavian Laboratory,” and the “Epidemiologist's Dream”
Authors: Bauer Susanne
Published: April 2014

Argument

Since the 1970s, Danish population registries were increasingly used for research purposes, in particular in the health sciences. Linked with a large number of disease registries, these data infrastructures became laboratories for the development of both information technology and epidemiological studies. Denmark's system of population registries had been centralized in 1924 and was further automated in the 1960s, with individual identification numbers (CPR-numbers) introduced in 1968. The ubiquitous presence of CPR-numbers in administrative routines and everyday lives created a continually growing data archive of the entire population. The resulting national-level database made possible unprecedented record linkage, a feature epidemiologists and biomedical scientists used as a resource for population health research. The specific assemblages that emerged with their practices of data mining were constitutive of registry-based epidemiology as a style of thought and of a distinct relationship between science, citizens, and the state that emerged as “Scandinavian.”
Producing Standards, Producing the Nordic Region: Antibiotic Susceptibility Testing, from 1950–1970
Authors: Lie Anne Kveim
Published: April 2014

Argument

During the 1950s it became apparent that antibiotics could not conquer all microbes, and a series of tests were developed to assess the susceptibility of microbes to antibiotics. This article explores the development and standardization of one such testing procedure which became dominant in the Nordic region, and how the project eventually failed in the late 1970s. The standardization procedures amounted to a comprehensive scheme, standardizing not only the materials used, but also the methods and the interpretation of the results. Focusing on Sweden and Norway in particular, the article shows how this comprehensive standardization procedure accounted for several co-dependent factors and demanded collaboration within and across laboratories. Whereas literature on standardization has focused mostly on how facts and artefacts move within and across laboratories, I argue for the importance of also attending to regions and territories. More particularly, while arguing that the practices, ideals, and politics related to what have been called the “Nordic welfare state” were contributing to the design of the standardized procedure in the laboratory, I also argue that Scandinavia was drawn together as a unified region with and by these very same practices.
InventingHomo gardarensis: Prestige, Pressure, and Human Evolution in Interwar Scandinavia
Authors: Kjærgaard Peter C.
Published: April 2014

Argument

In the 1920s there were still very few fossil human remains to support an evolutionary explanation of human origins. Nonetheless, evolution as an explanatory framework was widely accepted. This led to a search for ancestors in several continents with fierce international competition. With so little fossil evidence available and the idea of a Missing Link as a crucial piece of evidence in human evolution still intact, many actors participated in the scientific race to identify the human ancestor. The curious case ofHomo gardarensisserves as an example of how personal ambitions and national pride were deeply interconnected as scientific concerns were sometimes slighted in interwar palaeoanthropology.
A New Method to Accelerate PPP Convergence Time by using a Global Zenith Troposphere Delay Estimate Model
Authors: Yao Yibin , Yu Chen , Hu Yufeng
Published: April 2014

This paper presents a new algorithm to accelerate Precise Point Positioning (PPP) convergence. The main idea is to consider the station tropospheric zenith total delay, which is obtained by a global zenith troposphere delay estimate model, as virtual observation and combine it with phase and pseudo-range observations to formulate observation equations. Without relying on any other external enhancement information, it only requires four satellites to quickly complete the positioning with centimetre-level accuracy. Compared with the conventional method, the new one brings about 15% improvement in convergence time.
The spatial diffusion of norovirus epidemics over three seasons in Tokyo
Authors: INAIDA S. , SHOBUGAWA Y. , MATSUNO S. , SAITO R. , SUZUKI H.
Published: April 2014

We studied the spatial trend of norovirus (NoV) epidemics using sentinel gastroenteritis surveillance data for patients aged <15 years (n = 140) in the Tokyo area for the 2006–2007 to 2008–2009 seasons utilizing the kriging method of geographical information system (GIS). This is the first study of the spreading pattern of NoV epidemics using sentinel surveillance data. Correlations of sentinel cases between the seasons and with demographic data were examined to identify the trend and related factors. A similar pattern of diffusion was observed over the seasons, and its mean correlation between seasons was significantly high. A higher number of cases were found in the peripheral area, which surrounds the most populated central area, and showed a correlation with the ratio of the children population (r = 0·321, P < 0·01) and the ratio of residents in larger families (r = 0·263, P < 0·01). While NoV susceptibility remained, the results suggest a transmission route in the local community as a possible epidemic factor. Prevention with focus on the peripheral area is desirable.
Multiple vectors of unidirectional dialect change in eastern New England
Authors: Stanford James N. , Severance Nathan A. , Baclawski Kenneth P.
Published: April 2014

Traditional eastern New England (ENE) dialect features are rapidly receding in many parts of northern New England. Because this ENE shift involves seven different phonological features, it provides a prime opportunity to explore different rates of change across multiple linguistic variables at the same time in the same social setting. The present study is the first acoustic sociophonetic investigation of central New Hampshire, and it is based on new field data from 51 adult speakers. Results show that young generations are discarding many traditional ENE pronunciations in favor of leveled, nonregional forms, yet the changes are affecting some variables more quickly than others. Many distinctive traditional ENE variants (nonrhotic speech, intrusive-r, frontedfather, “broad-a” inbath) are quickly receding, while others (frontedstartandhoarse/horsedistinction) are somewhat more conservative, being “overshadowed” by the presence of (r) as a variable within the same syllable. We frame our apparent-time analysis in terms of Sankoff's (2013a) notion of “age vectors” and Labov's (2012) “outward orientation” of the language faculty, illustrating how different generations are juggling multiple age vectors within the same overall shift, and how one variable can overshadow another variable within the same syllable.
Cycles Are Strongly Ramsey-Unsaturated
Authors: SKOKAN J. , STEIN M.
Published: April 2014

We call a graph H Ramsey-unsaturated if there is an edge in the complement of H such that the Ramsey number r(H) of H does not change upon adding it to H. This notion was introduced by Balister, Lehel and Schelp in [J. Graph Theory51 (2006), pp. 22–32], where it is shown that cycles (except for C4) are Ramsey-unsaturated, and conjectured that, moreover, one may add any chord without changing the Ramsey number of the cycle Cn, unless n is even and adding the chord creates an odd cycle.

We prove this conjecture for large cycles by showing a stronger statement. If a graph H is obtained by adding a linear number of chords to a cycle Cn, then r(H)=r(Cn), as long as the maximum degree of H is bounded, H is either bipartite (for even n) or almost bipartite (for odd n), and n is large.

This motivates us to call cycles strongly Ramsey-unsaturated. Our proof uses the regularity method.
In mouse oocytes the mitochondrion-originated germinal body-like structures accumulate mouseVasahomologue (MVH) protein
Authors: Reunov Arkadiy A. , Reunova Yulia A.
Published: April 2014

MouseVasahomologue (MVH) antibodies were applied to mouse Graafian oocytes to clarify if mitochondrion-originated germinal body-like structures, described previously by conventional electron microscopy, were associated with the germ plasm. It was found that both the mitochondrion-like structures with cristae and the germinal body-like structures that lacked any signs of cristae were labelled specifically by the anti-MVH antibody. Moreover, some granules were MVH-positive ultrastructural hybrids of the mitochondria and germinal body-like structures, the presence of which clearly supported the idea of a mitochondrial origin for the germinal body-like structures. This finding is the first evidence that mitochondrion-originated germinal body-like granules represent mouse germ plasm.
Socioeconomic and Psychological Aspects of Disasters
Authors: Glittenberg JoAnn
Published: April 2014

Recovery and reconstruction following major sociocultural upheavals, such as natural disasters and war, result in multiple changes. In addition to loss of life and property, social structures and ways of life are temporarily and sometimes permanently altered. Sources of change are both from within due to loss and damage as well as from the outside through new ideas, relief, and economic aid. Some aspects of change may be viewed positively, as a society measures the benefits, while still other aspects may be worthless or detrimental to the survival of the group.

Because of the magnitude of the 1976 Guatemalan Earthquake, as well as the unprecedented outpouring of disaster relief and reconstruction aid, a longitudinal study funded by National Science Foundation was begun in 1977 (18 months after the event) and extended through 1982 (in selected areas). Chiefly because of financial expense, most research studies of disasters are limited to short-term follow-up studies of several weeks to a year after the traumatic event. However, many scientists have urged the importance of doing longitudinal studies (1–3). This study had as an overall goal, the study of the process of recovery over a five year period post-Earthquake. A quasiexperimental design was used to compare the recovery process in 19 experimental and 7 control sites. The overall guiding research question was: Does a catastrophy or social upheaval stimulate the recovery of the society so that the level of living post-disaster is higher than the pre-disaster state? Level of Living was operationalized to include housing conditions, cost of living, as well as quality of life measures. The results of a specific portion of the 1976 Guatemalan Earthquake Study (as it is popularly called), the urban resettlements, is presented in this paper.
MODELS AND MATHEMATICS: HOW PIGOU CAME TO ADOPT THE IS-LM-MODEL REASONING
Authors: Takami Norikazu
Published: April 2014

The paper investigates how Arthur Pigou came to adopt the reasoning essentially based on the working of the IS-LM model and to admit that money wage cuts are neutral to employment under the liquidity trap. This occurred through his involvement in the controversy with John Maynard Keynes in 1937–38. In the first instance, Pigou used a simple model to oppose Keynes’s assertion on such neutrality. Pigou (and Keynes too) applied verbal logical analysis to the model to derive his conclusions. Submitting a paper to the Economic Journal, Nicholas Kaldor analyzed Pigou’s model in mathematical terms and asserted that Pigou derived inconsistent conclusions from his model. Kaldor’s method eventually convinced Pigou, Keynes, and Dennis Robertson (who participated in the debate in correspondence). The paper thus argues that the controversy was concluded when one form of model analysis replaced another; specifically, when mathematical analysis replaced verbal logical analysis. This study provides a case study to the first category of Mary Morgan’s two functions of economic modeling: models as an object to inquire into and models as an object with which to inquire.
Interpersonal Processes and Attachment in Voice-Hearers
Authors: Robson George , Mason Oliver
Published: April 2014

Background: Studies of both clinical and non-clinical voice hearers suggest that distress is rather inconsistently associated with the perceived relationship between voice and hearer. It is also not clear if their beliefs about voices are relevant. Aims: This study investigated the links between attachment anxiety/avoidance, interpersonal aspects of the voice relationship, and distress whilst considering the impact of beliefs about voices and paranoia. Method: Forty-four voice-hearing participants completed a number of self-report measures tapping attachment, interpersonal processes in the voice relationship, beliefs about voices, paranoia, distress and depression. Results: Attachment avoidance was related to voice intrusiveness, hearer distance and distress. Attachment anxiety was related to voice intrusiveness, hearer dependence and distress. A series of simple mediation analyses were conducted that suggest that the relationship between attachment and voice related distress may be mediated by interpersonal dynamics in the voice-hearer relationship, beliefs about voices and paranoia. Conclusions: Beliefs about voices, the hearer's relationship with their voices, and the distress voices sometimes engender appear to be meaningfully related to their attachment style. This may be important to consider in therapeutic work.
Microlensing Constraints on the Abundance of Extrasolar Planets
Authors: Cassan Arnaud ,   PLANET,   OGLE
Published: April 2014

Galactic gravitational microlensing is a powerful technique to detect extrasolar planets at large orbital distances from their stars, from giant down to Earth-mass planets. We report a statistical analysis (Cassan et al. 2012) that combines six years of microlensing observations gathered between 2002 to 2007 by the PLANET and OGLE collaborations. From these data, we estimate the frequency of cool extrasolar planets, with masses ranging from 5 Earths to 10 Jupiters and orbits between 0.5 to 10 Astronomical Units. We find that in average, one in six stars has a Jupiter-like gas giant as companion planet, that about half the stars are orbited by a Neptune-like giant, and two-thirds are associated to super-Earths. Our study also suggests that planets should be ubiquitous throughout the Galaxy. Current deployment of wide-field imagers and possible space-based observations onboard ESA spacecraft EUCLID will soon allow a large increase of the number of monitored microlensing events. These new observatories should provide in a near future a more detailed view on planet abundance as a function of mass.
Detection of O2 Produced Abiotically on Habitable but Lifeless Planets around M-dwarfs
Authors: Li Tong , Tian Feng
Published: April 2014

High atmospheric abundances of oxygen has been widely considered to be a reliable biosignature for life on exoplanets in the habitable zones of all types of stars. Recently it was proposed that the unique UV spectra of observed planet-hosting M dwarfs could lead to the buildup of molecular oxygen in the atmospheres of habitable but lifeless planets around these stars (Tian et al. 2014). However, the detectability of the accumulated O2 was not modeled. In this work we developed a new line by line radiative transfer model based on HITRAN database and used the model to simulate the reflectivity in the visible and near IR range. We show that abiotically produced and maintained O2 in the 0.2% level is observable at 13105 cm−1 (0.76 μm) with the spectra resolution of 70.
Habitable Zone Super-Earths with Non-Stabilised Spectrographs
Authors: Wright Duncan J. , Tinney Christopher G. , Wittenmyer Robert A.
Published: April 2014

Detecting the small velocity amplitudes (≤ 10 m/s) produced by habitable zone rocky planets around M Dwarfs requires radial velocity precisions of a few m s−1. However, an iodine absorption cell, commonly used as a high precision wavelength reference on non-stabilised spectrographs, is not efficient for very red and faint objects like M Dwarfs. Instead, arc lamps have to be used. With the exception of the ultra-stabilised HARPS spectrograph, achieving ~m s−1 calibration with arc lamps has not been possible because typical spectrographs experience drifts of several hundred m s−1 due to local atmospheric changes in pressure and temperature. We outline and present results from an innovative differential wavelength calibration method that enables ~m s−1 precision from non-stabilised, high-resolution spectrographs. This technique allows the detection of rocky planets with radial velocity amplitudes of a few m s−1.
A Step Toward Eta-sub-Earth
Authors: Traub Wesley A.
Published: April 2014

The Kepler mission observed exoplanet transits for 4 full years (greater than its expected lifetime of 3.5 years) until it became inoperable for its original purpose, as a result of a reaction wheel failure. Kepler was spectacularly successful in its goal of observing exoplanet transits of host star disks for the purpose of measuring the statistics of such transits in its target star sample. The Kepler data, when fully analyzed, will determine the statistics of planets in the underlying population, and in particular the expected number of terrestrial planets in habitable zone orbits per solar-type star, the quantity known as eta-sub-Earth. This report is an initial examination of Kepler's third catalog (Feb. 2012) of planets and candidate planets. I find that the apparent projected value of eta-sub-Earth is several times smaller than I had found from the second catalog, but that the data are now approaching the point where intrinsic biases can be uncovered. When all bias factors are eventually found, it is likely that the true value of eta-sub-Earth will be substantially greater than its current apparent value.
Auto-Vetting Transiting Planet Candidates Identified by the Kepler Pipeline
Authors: Jenkins Jon M. , McCauliff Sean , Burke Christopher , Seader Shawn , Twicken Joseph , Klaus Todd , Sanderfer Dwight , Srivastava Ashok , Haas Michael R.
Published: April 2014

The Kepler Mission simultaneously measures the brightness of more than 150,000 stars every 29.4 minutes primarily for the purpose of transit photometry. Over the course of its 3.5-year primary mission Kepler has observed over 190,000 distinct stars, announcing 2,321 planet candidates, 2,165 eclipsing binaries, and 105 confirmed planets. As Kepler moves into its 4-year extended mission, the total number of transit-like features identified in the light curves has increased to as many as ~18,000. This number of signals has become intractable for human beings to inspect by eye in a thorough and timely fashion. To mitigate this problem we are developing machine learning approaches to perform the task of reviewing the diagnostics for each transit signal candidate to establish a preliminary list of planetary candidates ranked from most credible to least credible. Our preliminary results indicate that random forests can classify potential transiting planet signatures with an accuracy of more than 98.6% as measured by the area under a receiver-operating curve.
The Configuration Formation of Planetary Systems Observed by Kepler
Authors: Wang Su , Ji Jianghui
Published: April 2014

The Kepler mission has found many planetary systems, among them more than 80 systems host three planet candidates which reveal a configuration of near 4:2:1 mean motion resonance. In this paper, we focus on the configuration formation of resonant systems. As shown from our model and N-body simulations, we find that 3:2 mean motion resonance always forms at the early stage of star evolution and planets undergo high rate of migration, while 2:1 mean motion resonance happens at the late stage of the star formation, more often.
On the Planetary Orbital Period Ratio Distribution In Multiple Planet Systems
Authors: Xie Ji-Wei
Published: April 2014

Many multiple planet systems have been found by both radial velocity (RV) and transit surveys, such as theKeplermission. Period ratio distribution of these planet candidates show that they do not prefer to be in or near Mean Motion Resonance (MMR). Nevertheless, there are small but significant excesses of candidate pairs both spaced slightly exterior to exact resonance, particular near the first order of MMR, such as 2:1 and 3:2. Here, we first review recent observational constraints on these multiple transiting systems and theoretical models, which attempt to understand their period ratio distributions. Then we identify a statistical effect based on an intrinsic asymmetry associated with MMR, and find it play an important role in shaping the period ratio distribution near MMR. Last but least, we also find such an intrinsic asymmetry is existing in asteroids of our solar system.
Inclinations of Circumbinary Planets: Assembly of Protoplanetary Discs and Secular Binary-Disc Interaction
Authors: Lai Dong , Foucart Francois
Published: April 2014

The Kepler satellite has discovered a number of transiting planets around close binary stars. These circumbinary systems have highly aligned planetary and binary orbits. In this paper, we explore how the mutual inclination between the planetary and binary orbits may reflect the physical conditions of the assembly of protoplanetary discs and the interaction between protostellar binaries and circumbinary discs. Given the turbulent nature of star-forming molecular clouds, it is possible that the infalling gas onto the outer region of a circumbinary disc rotates around a different axis compared to the central protostellar binary. Thus, the newly assembled circumbinary disc can be misaligned with respect to the binary. However, the gravitational torque from the binary produces warp and twist in the disc, and the back-reaction torque tends to align the disc and the binary orbital plane. We present a new, analytic calculation of this alignment torque, and show that the binary-disc inclination angle can be reduced appreciably after the binary accretes a few percent of its mass from the disc. Since mass accretion onto the proto-binary is very likely to occur, our calculation suggests that in the absence of other disturbances, circumbinary discs and planets around close (sub-AU) stellar binaries are highly aligned with the binary orbits, while discs and planets around wide binaries can be misaligned.
Trojans in Exosystems with Two Massive Planets
Authors: Dvorak Rudolf , Zhou Li-Yong , Baudisch Helmut
Published: April 2014

We take as dynamical model for extrasolar planetary systems a central star like our Sun and two giant planets m1 and m2 like Jupiter and Saturn. We change the mass ratio μ=m2/m1 of the two large planets for a wide range of 1/16 < μ < 16. We also change the ratio between the initial semi-major axes (ν=a2/a1) in the range of 1.2 < ν < 3 to model the different architecture of extrasolar planetary systems hosting two giant planets. The results for possible Trojans (Trojan planets) in the equilateral equilibrium points of the inner planet m1 and the outer planet m2 were derived with the aid of numerical integration. It turned out that in many configurations – depending on the mass ratios μ and the semi-major axes ratio ν – giant planets may host Trojans.
Constraints on the Habitability of Extrasolar Moons
Authors: Heller René , Barnes Rory
Published: April 2014

Detections of massive extrasolar moons are shown feasible with the Kepler space telescope. Kepler's findings of about 50 exoplanets in the stellar habitable zone naturally make us wonder about the habitability of their hypothetical moons. Illumination from the planet, eclipses, tidal heating, and tidal locking distinguish remote characterization of exomoons from that of exoplanets. We show how evaluation of an exomoon's habitability is possible based on the parameters accessible by current and near-future technology.
Activity-Induced Radial Velocity Variation of M Dwarf Stars
Authors: Andersen Jan Marie , Korhonen Heidi
Published: April 2014

Stellar magnetic activity manifests itself in a variety of ways including starspots–cool, dark regions on the stellar surface. Starspots can cause variations (‘jitter’) in spectral line-profiles which can mimic the radial velocity (RV) variations caused by an orbiting planet, or create RV noise that can drown out a planetary signature. Cool, low-mass M dwarf stars can be highly active, which can make detection of potentially habitable planets around these stars difficult. We investigate radial velocity variations caused by different activity (spot) patterns on M dwarf stars in order to determine the limits of detectability for small planets orbiting active M dwarfs. We report on our progress toward the aim of answering the following questions: What types of spot patterns are realistic for M dwarf stars? What effect will spots have on M dwarf RV measurements? Can jitter from M dwarf spots mimic planetary signals? What is the ideal observing wavelength to reduce M dwarf jitter?
The Elemental Compositions of Extrasolar Planetesimals
Authors: Jura M.
Published: April 2014

Evidence is now compelling that most externally-polluted white dwarfs derive their heavy atoms by accretion from asteroids – the building blocks of rocky planets. Optical and ultraviolet spectroscopy of a small sample of suitable white dwarf stars shows that to zeroth order, the accreted extrasolar parent bodies compositionally resemble bulk Earth. (1) Extrasolar planetesimals are at least 85% by mass composed of O, Mg, Si and Fe. (2) Compared to the Sun, C is often deficient, usually by at least a factor of 10 and therefore comprises less than 1% of an extrasolar planetesimal's mass. At least to-date, C has never been found to be enhanced as would be expected if carbon-rich planetesimals have formed. (3) While there may be individual exceptions, considered as a whole, the population of extrasolar asteroids accreted onto a well-defined sample of local white dwarf stars is less than 1% water by mass.
Laminar Accretion in the Habitable Zone of Protoplanetary Disks
Authors: Bai Xue-Ning , Stone James M.
Published: April 2014

Protoplanetary disks (PPDs) are widely believed to be turbulent as a result of the magnetorotational instability (MRI). We perform magnetohydrodynamical simulations of PPDs that for the first time, take into account both Ohmic resistivity and ambipolar diffusion in a self-consistent manner. We show that in the inner region of PPDs that corresponds the habitable zone, the MRI is completely suppressed due to the interplay between magnetic field and ambipolar diffusion. The gas in this region is laminar throughout the entire vertical extent of the disk. Instead of MRI-driven accretion, a strong magnetocentrifugal wind is launched that efficiently carries away disk angular momentum. A physical wind geometry requires the presence of a strong current layer that is offset from the disk midplane where horizontal magnetic fields flip. We show that the entire accretion flow proceeds through this strong current layer. The non-turbulent nature of the gas flow strongly favors the habitable zone as the site for planetesimal formation, and has important implications for their subsequent growth into terrestrial planets.
Type I Planet Migration in Weakly Magnetized Laminar Disks
Authors: Guilet Jérôme , Baruteau Clément , Papaloizou John C. B.
Published: April 2014

Planet migration plays a crucial role in shaping planetary systems, and has therefore received a lot of attention in recent years in an effort to compare the statistical properties of observed exoplanets with the predictions of planet formation and migration theories. By modifying the propagation properties of the waves induced by the planet in the disk, the presence of a strong magnetic field can dramatically influence planet migration, in some cases reversing its direction. The more realistic case of a weaker magnetic field is less clear, although turbulent MHD simulations by Baruteau et al. (2011) suggest an effect on the corotation torque. Here, we present a study of the corotation torque in 2D laminar disks containing a toroidal magnetic field. We performed MHD simulations of the interaction between the magnetic field and the horseshoe motion of the gas, and found that this results in an additional corotation torque. This additional torque can be strong enough to reverse migration even for a field which pressure is only one percent of the thermal pressure. We speculate that this could lead to long range outward migration in the outer part of protoplanetary disks and may explain the observations by direct imaging of planets at several tens of AU from their star like the 4 planets system HR 8799.
Determining the Origin of Inner Planetary System Debris Orbiting the Dustiest Main Sequence Stars
Authors: Melis Carl , Zuckerman B. , Rhee Joseph H. , Song Inseok , Murphy S. J. , Bessell M. S.
Published: April 2014

We develop a means to distinguish between warm dusty circumstellar debris disks produced by steady state collisional evolution of a planetesimal belt or through transient events.
Angular Momenta of Collided Rarefied Preplanetesimals
Authors: Ipatov Sergei I.
Published: April 2014

The angular momenta of rarefied preplanetesimals needed for formation of small-body binaries can be obtained at collisions of preplanetesimals. Trans-Neptunian objects, including trans-Neptunian binaries, could be formed from contracting rarefied preplanetesimals.
Atmospheric Characterization of Cold Exoplanets Using a 1.5-m Space Coronagraph
Authors: Maire Anne-Lise , Galicher Raphaël , Boccaletti Anthony , Baudoz Pierre , Schneider Jean , Cahoy Kerri , Stam Daphne , Traub Wesley
Published: April 2014

We present numerical results of the science performance of the SPICES mission, which aims to characterize the spectro-polarimetric properties of cold exoplanets and circumstellar disks in the visible. We focus on the instrument ability to retrieve the spectral signatures of molecular species, clouds and surface of super-Earths in the habitable zone of solar-type stars. Considering realistic reflected planet spectra and instrument limitation, we show that SPICES could analyse the atmosphere and surface of a few super-Earths within 5 pc of the Sun.
Cloud and Gas Ionisation in Atmosphere of Gas-Giant Planets
Authors: Helling Ch. , Jardine M. , Stark C. , Rimmer P. , Diver D.
Published: April 2014

The steady increase of the sample of know extrasolar planets broadens our knowledge and at the same time, reveals our lack of understanding. Habitability is a wide expression, needing planet formation theory and microphysics of cloud formation at the same time. The habitability of a planet depends, amongst other things, on how much radiation reached the ground and how much of potentially dangerous radiation is absorbed on the way through the atmosphere. For this, we need to understand cloud formation and it's impact on the atmosphere.

We have studied the formation of mineral clouds on planetary atmospheres by a kinetic approach which allows us to predict the size distribution and material composition of the cloud particles. With these results we show that mineral cloud particles can be electrically charged and at which point inside a cloud charge separation will cause an electric field breakdown. Such streamer processes result in an extreme increase of the local number of free charges. Given the strong magnetic field in Brown Dwarfs and maybe in giant gas planets, these charges will than be accelerated upward out of the atmosphere where they become detectable as radio emission.
Climate of Eccentric Terrestrial Planets with Carbonate-Silicate Geochemical Cycle
Authors: Kadoya Shintaro , Tajika Eiichi , Watanabe Yoshiyasu
Published: April 2014

Recent discovery of extrasolar planets indicates that some of them have much higher eccentricity than the planets in the solar system. Here, we investigate the climate of such eccentric terrestrial planets with oceans and carbonate-silicate geochemical cycles. We find that the climate of the planets are dependent on the annual mean insolation as shown in previous works. We also find that the planets orbiting slightly further from our Sun than the Earth are globally ice-covered even if the carbonate-silicate geochemical cycle works under the same CO2 degassing rate as on the present Earth. However, when the CO2 degassing rate is higher, the planets avoid being globally ice-covered owing to the high level.
Climate of Extraterrestrial Planets with Oceans and Carbonate-Silicate Geochemical Cycle Under Various Obliquities
Authors: Watanabe Yoshiyasu , Tajika Eiichi , Kadoya Shintaro
Published: April 2014

We systematically investigated the climate of water-rich terrestrial planets with a negative feedback mechanism of carbonate-silicate geochemical cycle against the climate under various obliquities and semi-major axes. We found that, while the permanent ice-cap mode (partially ice-covered throughout the year) and the seasonal ice-cap mode (partially ice-covered seasonally) exist stably at low obliquity conditions, the ranges of semi-major axis for these climate modes shrink and finally disappear with an increase of obliquity. When carbonate-silicate geochemical cycle is taken into account, the ranges of semi-major axis for all the climate modes expand at any obliquities, compared with the cases without carbonate-silicate geochemical cycle, indicating that the carbonate-silicate geochemical cycle strongly stabilizes the climate for the planets with any obliquities inside the habitable zone.
The Complete Evaporation Limit of Land Planets
Authors: Takao Yuya , Genda Hidenori , Wakida Miyuki , Abe Yutaka
Published: April 2014

Planets with very little amount of water on their surface, called “land planets”, have wider habitable zones than that of Earth-like “aqua planets” (Abe et al. 2011). We investigated complete evaporation of surface liquid water for land planets using 1D energy balance model (EBM). We found that complete evaporation occurs when the planetary flux at the dry edge, which is defined as the boundary between the dry zone and the wet zone, exceeds the critical radiation flux of water saturated atmosphere. We define “complete evaporation limit” as the minimum insolation for complete evaporation that a planet receives. This limit depends on latitude of the dry edge, efficiency of meridional heat transport, and atmospheric character that modify the value of the critical flux.
Mass-Radius Relationships of Rocky Exoplanets
Authors: Sohl Frank , Wagner Frank W. , Rauer Heike
Published: April 2014

Mass and radius of planets transiting their host stars are provided by radial velocity and photometric observations. Structural models of solid exoplanet interiors are then constructed by using equations of state for the radial density distribution, which are compliant with the thermodynamics of the high-pressure limit. However, to some extent those structural models suffer from inherent degeneracy or non-uniqueness problems owing to a principal lack of knowledge of the internal differentiation state and/or the possible presence of an optically thick atmosphere. We here discuss the role of corresponding measurement errors, which adversely affect determinations of a planet's mean density and bulk chemical composition. Precise measurements of planet radii will become increasingly important as key observational constraints for radial density models of individual solid low-mass exoplanets or super-Earths.
Anelastic Tidal Dissipation in Multi-Layer Planets
Authors: Remus Françcoise , Mathis Stéphane , Zahn Jean-Paul , Lainey Valéry
Published: April 2014

Earth-like planets have anelastic mantles, whereas giant planets may have anelastic cores. As for the fluid parts, the tidal dissipation of these regions, gravitationally perturbed by a companion, highly depends on its internal friction and thus its internal structure. Therefore, modeling this kind of interaction presents a high interest to constrain planetary interiors, whose properties are still quite uncertain. Here, we examine the anelastic tidal dissipation in deep planetary interiors, in presence of a fluid envelope, and taking into account its dependence on the rheology.

Taking plausible values for the anelastic parameters, and discussing the frequency-dependence of the anelastic dissipation, we show how this mechanism may compete with the dissipation in fluid layers, when applied to Jupiter- and Saturn-like planets. We also discuss the case of the icy giants Uranus and Neptune. Finally, we show how the results may be implemented to describe the dynamical evolution of planetary systems.
Direct Imaging of Planet Transit Events
Authors: van Belle Gerard T. , von Braun Kaspar , Boyajian Tabetha , Schaefer Gail
Published: April 2014

Exoplanet transit events are attractive targets for the ultrahigh-resolution capabilities afforded by optical interferometers. The intersection of two developments in astronomy enable direct imaging of exoplanet transits: first, improvements in sensitivity and precision of interferometric instrumentation; and second, identification of ever-brighter host stars. Efforts are underway for the first direct high-precision detection of closure phase signatures with the CHARA Array and Navy Precision Optical Interferometer. When successful, these measurements will enable recovery of the transit position angle on the sky, along with characterization of other system parameters, such as stellar radius, planet radius, and other parameters of the transit event. This technique can directly determine the planet's radius independent of any outside observations, and appears able to improve substantially upon other determinations of that radius; it will be possible to extract wavelength dependence of that radius determination, for connection to characterization of planetary atmospheric composition & structure. Additional directly observed parameters - also not dependent on transit photometry or spectroscopy - include impact parameter, transit ingress time, and transit velocity.
Starspot-Induced Radial Velocity Jitter During a Stellar Cycle
Authors: Korhonen Heidi , Andersen Jan Marie , Järvinen Silva
Published: April 2014

Late-type stars exhibit cool regions on their surface, the stellar equivalent of sunspots. These dark starspots can also mimic the radial velocity variations caused by orbiting planets, making it at times difficult to distinguish between planets and activity signatures. The amount of spots on the Sun and other cool stars changes cyclically during an activity cycle, which has length varying from about a year to longer than the solar 11 years. In this work we investigate the influence of varying amount of starspots on the sparsely sampled radial velocity observations - which are the norm in the radial velocity studies searching for exoplanets on wide orbits. We study two simulated cases: one with a random spot configuration, and one where the spot occurrence is concentrated. In addition we use Doppler images of young solar analogue V889 Her as a high activity case.
Superflares on Late-Type Stars
Authors: Maehara Hiroyuki , Shibayama Takuya , Notsu Yuta , Notsu Shota , Nagao Tanashi , Honda Satoshi , Nogami Daisaku , Shibata Kazunari
Published: April 2014

We present the results of an extensive survey of superflares on late-type stars (G, K, and M-type main sequence stars) using the Kepler satellite data. Wefound about 6,800 superflares on late-type stars from the data of about 120,000 stars observed over 500 days. The total bolometric energy of superflares in oursample ranges from 1032 erg to 1036 erg. Our data suggest that the occurrencefrequency of superflares depends on the surface temperature and the rotationperiod of stars. Superflares on M-type stars occur about 10-100 times morefrequently than those on G-type stars. Our results suggest that the average frequency ofsuperflares releasing 1034–1035 erg of energy (100-1,000 times larger than the largestsolar flares) on M-type stars and Sun-like stars is once in 10 years and once in a few thousand years respectively.