bluuebunny/crossref_metadata_2025 huggingface dataset:
Práticas de escrita escolar no ensino de História: indícios de significação do tempo em manuscritos escolares
Authors: Lima dos Santos Maria Aparecida
Published: February 2016

Neste artigo, assumindo como base teórico-metodológica as teorias da enunciação e do ensino de História no concernente aos processos de significação do tempo na História ensinada, analiso aspectos expressivos e contextuais de um manuscrito escolar de uma aluna de 6º ano, cuja produção é, socialmente, considerada insuficiente do ponto de vista de uma escrita convencional. Pautando-me pela relevância teórica dos dados singulares e pela compreensão do escrito pela estudante como prática discursiva, objetivo dar visibilidade a indícios que subsidiam a compreensão de aspectos da relação entre processos de significação do passado e da língua escrita, a fim de confrontar essa perspectiva social. Concluo destacando as potencialidades e a necessidade de se pensar os textos escritos por crianças e adolescentes como parte do intrincado mecanismo cultural e historicamente instituído através do qual o discurso histórico escolar se reproduz.
Jogos do tempo e processos de identificação hegemonizados nos textos curriculares de História
Authors: Gabriel Carmen Teresa
Published: February 2016

As pesquisas em ensino de história tendem a evidenciar a importância das questões de temporalidade e de identidade para a reflexão sobre os processos de produção e de distribuição desse conhecimento. O professor de História é sistematicamente interpelado e convocado a contribuir na construção e fixação de identidades  por meio da mobilização de experiências (passado) e projetos (futuro) coletivos e individuais selecionados como conteúdos a serem ensinados em cada presente. Em diálogo com as teorizações do discurso e os estudos narrativos, este texto tem por objetivo explorar os jogos do tempo que articulam passado, presente e futuro nas narrativas identitárias hegemonizadas nos Parâmetros Curriculares Nacionais de História que tem como leitor potencial o professor desta disciplina.
História Ensinada e Dialogismo: prática de letramento no 6º ano do Ensino Fundamental
Authors: Bastos de Azevedo Patricia
Published: February 2016

O presente estudo buscou investigar a produção de sentido em práticas de letramento na história ensinada, operando conceitualmente com o campo da linguagem a partir do Círculo de Bakhtin como arcabouço teórico em interface com o currículo. Como foco e recorte metodológico, investigou-se, em um tempo determinado do ano de 2009, o 6º ano de escolaridade do ensino fundamental no espaço específico da sala de aula de história de uma escola estadual no Rio de Janeiro/Baixada Fluminense. Na perspectiva teórica adotada, os enunciados se constituem no processo relacional situado, com um pano de fundo sociocultural, e o cenário composicional se relaciona diretamente com o emprego das enunciações e de suas relações intersubjetivas.
Ensino de História e Currículo: interfaces teóricas e metodológicas
Authors: Guerra Filho Sérgio Armando Diniz , De Lacerda Nascentes Isabelle
Published: February 2016

MONTEIRO, Ana Maria (et al.). Pesquisa em Ensino de História: entre desafios epistemológicos e apostas políticas. Rio de Janeiro: Mauad X: Faperj, 2014 (280 p).
As noções de usos do passado e de cultura histórica como instrumental analítico para a prática e a pesquisa no Ensino de História
Authors: Santana Silva Célia
Published: February 2016

ROCHA, Helenice; MAGALHÃES, Marcelo; RIBEIRO, Jaime; CIAMBARELLA,Alessandra (Org.). Ensino de História: usos do passado, memória e mídia. Rio de Janeiro: Ed. FGV, 2014. 280p.
High-Definition Logging-While-Drilling Microimages Provided in Real Time
Authors: Climer Eric , Ozol Christopher
Published: February 2016

Technology Update

The development of conventional reservoirs has typically involved minimal logging-while-drilling (LWD) technology, usually consisting of survey, gamma ray, and possibly resistivity tools. As production from conventional reservoirs declines, the need to obtain more production from each well increases. With attention shifting toward the development of vast unconventional and source rock reservoirs, achieving and sustaining economic production rates depends on new drilling and evaluation technologies.

More information is needed about the formation target and reservoir in order to understand the challenges of these unconventional plays. When thinking about a well’s production potential, key characteristics must be taken into consideration, such as stress orientation, anisotropy, secondary porosity, natural fractures, and the potential of fracture propagation. New tools and technologies are necessary to determine these formation characteristics in the complicated reservoirs being developed.

One tool that is used to provide information for optimizing stimulation and well placement is the LWD microimager. These tools produce detailed electrical images of the borehole and show natural and induced fractures, faults, formation breakout, vugs, and other fine details of the formation. An accurate depiction of these features from high-resolution borehole images enables improvements in completion design.

When developing an LWD microimager, several factors must be addressed to achieve an optimal image quality. These include the need for

A conductive wellbore fluid such as water-based drilling mud

A rotating drillpipe

Reasonable contrast between the mud resistivity and formation resistivity

Minimal clearance between measurement electrodes and the wellbore

These parameters are common to all LWD microimaging tools and some counterpart wireline tools, and are acknowledged in the tool specifications. Knowing these key constraints and the desired measurement outcomes, Weatherford developed the high-definition SineWave microimager with two measurement electrode sizes to match the resolution capability of wireline tools and mitigate the negative effects of standoff and eccentricity in the borehole.
Changing the Equation: Refracturing Shale Oil Wells
Authors: Jacobs Trent
Published: February 2016

Refracturing Revolution

As shale operators look for ways to survive amid the current downturn in oil prices, accelerating the refracturing of older horizontal wells is turning into one of the most attractive options. In years past, when oil prices were significantly higher, the more accepted proposition was to drill and complete new wells to increase production, book new reserves, and hold onto leases.

However, since late last year, the equation has been turned on its head. In many oil-rich plays, companies are realizing that refracturing is the more budget-friendly way to achieve cash flow. Compared with the USD 8 million to USD 16 million needed for a new well, most refracture jobs are reported to cost from USD 1 million to USD 3 million. In a well where all of the sunk costs have been recovered, the extra production and incremental reserves from refracturing can net several million dollars of added profit.

Tim Leshchyshyn, founder of FracKnowledge, said the current low-price market environment has become the biggest driver for companies to reinvest in their old oil wells. One operator that his company tracks is so sold on the idea that it is considering refracturing 500 to 1,000 wells this year.

“Refracturing is what everybody is banking on,” he said. “It is the thing they are trying to get figured out because there are going to be a lot of wells to do.” As operators and service companies climb their way up the learning curve, they are trying to determine which wells to refracture, which ones to bypass, and which plays it will work best in.

Only a few unconventional producers have published the results of their refracturing programs in oil-rich plays, and many others do not acknowledge having such programs at all. But there are years’ worth of case studies from gas-rich plays such as the Marcellus, Haynesville, and the Barnett, the birthplace of unconventional shale development, that indicate refracturing can be successfully applied in the oil-rich plays as well.

Mike Vincent, an independent consultant, is seeing unprecedented demand from operating companies for his courses on how, why, and where to do refracturing. While eager to learn all they can about refracturing, many of his clients are reluctant to discuss the topic publicly. “I think there are multiple reasons why there is radio silence right now,” Vincent said.

Companies still unsure of the success rate of refracturing may be trying to avoid overselling its potential to investors. Others are certain that it works quite well, Vincent said, but are staying quiet for competitive reasons, which includes the desire to buy out other operators’ offset wells and refracture them.
Low Oil Prices Increase Value of Big Data in Fracturing
Authors: Betz Jack
Published: February 2016

Shale operators are searching for insights to get the most value from hydraulic fracturing at a time of low oil prices.

Discovering these insights requires a closer analysis of well data in order to make more cost-effective field development decisions. “We are often working with short-term data and need to find a way to turn that into long-term well performance,” said Craig Cipolla, a senior completions engineering adviser at Hess, who spoke at the recent 2015 SPE Hydraulic Fracturing Technology Conference in The Woodlands, Texas.

Companies such as Hess and Noble Energy have invested in drilling test wells with hopes of recuperating costs by optimizing future treatments. “These [ studies] require significant resources and manpower, and we can only do a limited number of these, if any at all in some cases,” Cipolla said.

Southwestern Energy has taken a different approach. It takes less expensive measurements and feeds them into models that are custom-built to be more predictive for the given play. The company already has made cost-saving adjustments to its operations based on the results of its models.

Each approach aims to make fracturing more profitable, whether by improving recovery or finding ways to achieve the same level of production at a lower cost.

Productivity Index

Southwestern has created long-term flow simulations of its Marcellus Shale gas wells from what reservoir engineering manager and technical lead Michael Lynch called “nearly free data.”

His team learned from simulations that proppant loading was one of the most important variables for productivity. Wells with high proppant loading overperformed by 40% compared with the company’s 30-well production average in the Marcellus, and those with low proppant loading underperformed by 20%.

The team also found that close spacing between fracture stages in its Marcellus assets did not significantly drive productivity. So to save money, the company has been using a wider spacing of up to 500 ft and more proppant per stage.

The main measurement that Lynch and his colleagues use to populate flow simulations is the initial productivity index, which is determined by shutting the well in and slowly opening the choke over the course of 2 to 3 days after breaking through to gas.
National Profile of Physical Therapists in Critical Care Units of Sri Lanka: Lower Middle-Income Country
Authors: Sigera Ponsuge Chathurani , Tunpattu Tunpattu Mudiyanselage Upul Sanjeewa , Jayashantha Thambawitage Pasan , De Silva Ambepitiyawaduge Pubudu , Athapattu Priyantha Lakmini , Dondorp Arjen , Haniffa Rashan
Published: February 2016

Background

The availability and role of physical therapists in critical care is variable in resource-poor settings, including lower middle-income countries.

Objective

The aim of this study was to determine: (1) the availability of critical care physical therapist services, (2) the equipment and techniques used and needed, and (3) the training and continuous professional development of physical therapists.

Methods

All physical therapists working in critical care units (CCUs) of state hospitals in Sri Lanka were contacted. The study tool used was an interviewer-administered telephone questionnaire.

Results

The response rate was 100% (N=213). Sixty-one percent of the physical therapists were men. Ninety-four percent of the respondents were at least diploma holders in physical therapy, and 6% had non–physical therapy degrees. Most (n=145, 68%) had engaged in some continuous professional development in the past year. The majority (n=119, 56%) attended to patients after referral from medical staff. Seventy-seven percent, 98%, and 96% worked at nights, on weekends, and on public holidays, respectively. Physical therapists commonly perform manual hyperinflation, breathing exercises, manual airway clearance techniques, limb exercises, mobilization, positioning, and postural drainage in the CCUs. Lack of specialist training, lack of adequate physical therapy staff numbers, a heavy workload, and perceived lack of infection control in CCUs were the main difficulties they identified.

Limitations

Details on the proportions of time spent by the physical therapists in the CCUs, wards, or medical departments were not collected.

Conclusions

The availability of physical therapist services in CCUs in Sri Lanka, a lower middle-income country, was comparable to that in high-income countries, as per available literature, in terms of service availability and staffing, although the density of physical therapists remained very low, critical care training was limited, and resource limitations to physical therapy practices were evident.
Utilization of the Expanded Disability Status Scale as a distinctive instrument for walking impairment in persons with multiple sclerosis with mild disability
Authors: Kahraman Turhan , Savci Sema , Coskuner Poyraz Esra , Ozakbas Serkan , Idiman Egemen
Published: February 2016

BACKGROUND:

The Expanded Disability Status Scale (EDSS) is a well-established clinical measure to assess disability in multiple sclerosis (MS). Gait dysfunction is primarily considered for scoring only above EDSS 3.5. However, the changes in functional systems in below EDSS 3.5 may result gait disturbances.

OBJECTIVE:

To determine the distinctive ability of the EDSS 2.0 in terms of walking impairment as well as fatigue, depression, and quality of life in persons with MS with mild disability.

METHODS:

All participants underwent the neurological examination for generating an EDSS score and completed the measures of walking performance, as well as other measures of fatigue, depression, and quality of life. The participants were divided into two groups according to the EDSS scores (i.e. EDSS <2.0 and 2.0–3.5).

RESULTS:

Participants with EDSS 2.0–3.5 had significantly worse walking performance, as well as fatigue, depression, and quality of life levels than the participants with EDSS <2.0 ( p <  0.05). The EDSS significantly correlated with the measures of walking performance, as well as other measures of fatigue, depression, and quality of life.

CONCLUSIONS:

The EDSS 2.0 has a distinctive ability in terms of walking impairment as well as fatigue, depression, and quality of life.
Transvertebral direct current stimulation paired with locomotor training in chronic spinal cord injury: A case study
Authors: Powell Elizabeth Salmon , Carrico Cheryl , Raithatha Ravi , Salyers Emily , Ward Andrea , Sawaki Lumy
Published: February 2016

STUDY DESIGN:

This double-blind, sham-controlled, crossover case study combined transvertebral direct current stimulation (tvDCS) and locomotor training on a robot-assisted gait orthosis (LT-RGO).

OBJECTIVE:

Determine whether cathodal tvDCS paired with LT-RGO leads to greater changes in function and neuroplasticity than sham tvDCS paired with LT-RGO.

SETTING:

University of Kentucky (UK) HealthCare Stroke and Spinal Cord Neurorehabilitation Research at HealthSouth Cardinal Hill Hospital.

METHODS:

A single subject with motor incomplete spinal cord injury (SCI) participated in 24 sessions of sham tvDCS paired with LT-RGO before crossover to 24 sessions of cathodal tvDCS paired with LT-RGO. Functional outcomes were measured with 10 Meter Walk Test (10MWT), 6 Minute Walk Test (6MWT), Spinal Cord Independence Measure-III (SCIM-III) mobility component, lower extremity manual muscle test (MMT), and Berg Balance Scale (BBS). Corticospinal changes were assessed using transcranial magnetic stimulation.

RESULTS:

Improvement in 10MWT speed, SCIM-III mobility component, and BBS occurred with both conditions. 6MWT worsened after sham tvDCS and improved after cathodal tvDCS. MMT scores for both lower extremities improved following sham tvDCS but decreased following cathodal tvDCS. Corticospinal excitability increased following cathodal tvDCS but not sham tvDCS.

CONCLUSION:

These results suggest that combining cathodal tvDCS and LT-RGO may improve functional outcomes, increase corticospinal excitability, and possibly decrease spasticity. Randomized controlled trials are needed to confirm these conclusions.

SPONSORSHIP:

This publication was supported by the National Center for Research Resources and the National Center for Advancing Translational Sciences, National Institutes of Health, through Grant UL1TR000117, and the HealthSouth Cardinal Hill Stroke and Spinal Cord Endowment (1215375670).
Participation in leisure activities after stroke: A survey of community-residing stroke survivors in Nigeria
Authors: Vincent-Onabajo Grace , Blasu Cephas
Published: February 2016

BACKGROUND:

Leisure provides pleasure and relaxation, and has health benefits even after a stressful and life-changing event such as a stroke.

OBJECTIVE:

This study examined leisure participation among a sample of community-residing stroke survivors in Nigeria.

METHODS:

Fifty-five stroke survivors undergoing rehabilitation were consecutively recruited from two government hospitals in Northern Nigeria. Data on pre- and post-stroke participation, and socio-demographic (age, sex, marital, employment, and educational status) and clinical (level of disability, post-stroke duration, stroke type and side of hemiplegia/hemiparesis) attributes of the stroke survivors were obtained. Leisure participation was assessed in four domains of recreational, social, cognitive, and productive/creative activities. Associations between leisure participation and the socio-demographic and clinical variables were examined using bivariate analysis.

RESULTS:

Mean (SD) age of the stroke survivors was 53.55 (14.39) years. Prevalence of leisure participation was 89.1%. Participation in specific leisure domains however varied thus: social (83.6%), cognitive (60%), recreational (41.8%), productive/creative activities (30.9%). Significant associations were observed between participation in cognitive, productive/creative, and recreational leisure activities, and specific socio-demographic and clinical attributes.

CONCLUSIONS:

Leisure participation was high in a general sense but marginal in recreational and productive/creative activities. The observed socio-demographic and clinical associations with post-stroke leisure participation may assist in providing effective leisure rehabilitation strategies.
Using reliability of change analysis to evaluate post-acute neuro-rehabilitation
Authors: Palmer Christina , Kneebone Ian I. , Strauss Clara , Jones Anna-Marie
Published: February 2016

BACKGROUND:

It is important to evaluate change in order to re-assure commissioners, staff and patients of the effectiveness of interventions, but also in order to identify areas for improvement.

OBJECTIVE:

To consider whether analysis of improvement at the level of the individual, taking into account measurement error, may offer a further valuable way to assess change and inform service development over considering change at the group level in a post-acute neuro-rehabilitation unit.

METHOD:

Pre and post intervention Scores on the FIM+FAM Full Scale and Cognitive and Motor subscales were considered for eighteen patients aged between 35 and 81 with mixed diagnoses who attended a post-acute inpatient neuro-rehabilitation unit for treatment.

RESULTS:

Statistically significant improvements were achieved on the FIM+FAM Full Scale and Cognitive and Motor subscales in a whole group analysis. Reliable change analyses for each patient within each subscale however identified only half of the sample achieved reliable improvement within the Motor domain and just one person within the Cognitive domain (5.6%).

CONCLUSIONS:

Findings are consistent with the emphasis of the rehabilitation unit on physical/motor function, and unsurprising as many of those assessed had multiple sclerosis, an often deteriorative condition. Use of reliable change analysis allowed a more detailed understanding of intervention impact, potentially identifying what services reliably work for whom, thereby informing future planning.
A CONSTRAINT ON QUASAR CLUSTERING AT z = 5 FROM A BINARY QUASAR*
Authors: McGreer Ian D. , Eftekharzadeh Sarah , Myers Adam D. , Fan Xiaohui
Published: February 2016

We report the discovery of a quasar pair at z = 5 separated by 21″. Both objects were identified as quasar candidates using simple color selection techniques applied to photometric catalogs from the Canada–France–Hawaii Telescope (CFHT) Legacy Survey (CFHTLS). Spectra obtained with the MMT present no discernible offset in redshift between the two objects; on the other hand, there are clear differences in the emission line profiles and in the multiwavelength spectral energy distributions that strongly disfavor the hypothesis that they are gravitationally lensed images of a single quasar. Both quasars are surprisingly bright given their proximity (a projected separation of ∼135 kpc), with i = 19.4 and i = 21.4. Previous measurements of the luminosity function demonstrate that luminous quasars are extremely rare at z = 5; the existence of this pair suggests that quasars have strong small-scale clustering at high redshift. Assuming a real-space correlation function of the form ξ(r) ∝ (r/r
0)−2, this discovery implies a correlation length of r
0 ≳ 20h
−1 Mpc, consistent with a rapid strengthening of quasar clustering at high redshift as seen in previous observations and predicted by theoretical models where feedback effects are inefficient at shutting down black hole growth at high redshift.
A MULTIRATE VARIABLE-TIMESTEP ALGORITHM FOR N-BODY SOLAR SYSTEM SIMULATIONS WITH COLLISIONS
Authors: Sharp P. W. , Newman W. I.
Published: February 2016

We present and analyze the performance of a new algorithm for performing accurate simulations of the solar system when collisions between massive bodies and test particles are permitted. The orbital motion of all bodies at all times is integrated using a high-order variable-timestep explicit Runge–Kutta Nyström (ERKN) method. The variation in the timestep ensures that the orbital motion of test particles on eccentric orbits or close to the Sun is calculated accurately. The test particles are divided into groups and each group is integrated using a different sequence of timesteps, giving a multirate algorithm. The ERKN method uses a high-order continuous approximation to the position and velocity when checking for collisions across a step. We give a summary of the extensive testing of our algorithm. In our largest simulation—that of the Sun, the planets Earth to Neptune and 100,000 test particles over 100 million years—the relative error in the energy after 100 million years was of the order of 10−11.
SIMULTANEOUS OBSERVATIONS OF GIANT PULSES FROM PULSAR PSR B0031-07 AT 38 AND 74 MHz
Authors: Tsai Jr-Wei , Simonetti John H. , Bear Brandon , Gough Jonathan D. , Newton Joseph R. , Kavic Michael
Published: February 2016

The first station of the Long Wavelength Array was used to study PSR B0031-07 with simultaneous observations at 38 and 74 MHz. We found that 158 (0.35%) of the observed pulses at 38 MHz and 221 (0.49%) of the observed pulses at 74 MHz qualified as giant pulses (GPs) in a total of 12 hr of observations. GPs are defined as having flux densities of a factor of ≥90 times that of an average pulse (AP) at 38 MHz and ≥80 times that of an AP at 74 MHz. The cumulative distribution of pulse strength follows a power law, with an index of −4.2 at 38 MHz and −4.9 at 74 MHz. This distribution has a much more gradual slope than would be expected if observing the tail of a Gaussian distribution of normal pulses. The dispersion measure (DM) value which resulted in the largest signal to noise for dedispersed pulses was DM = 10.9 pc cm−3. No other transient pulses were detected in the data in the wide DM range from 1 to 5000 pc cm−3. There were 12 GPs detected within the same period from both 38 and 74 MHz, meaning that the majority of them are not generated in a wide band.
PHOTOMETRIC AND PERIOD INVESTIGATION OF THE LATE F-TYPE OVERCONTACT BINARY II UMa
Authors: Zhou X. , Qian S.-B. , Zhang J. , Zhang B. , Kreiner J.
Published: February 2016

II UMa is a late F-type (F5) contact binary with a close-in tertiary and a distant visual companion. According to the four-color (B V R

c

I

c
) light curves’ solutions of II UMa, it is a high fill-out (f = 

) and low-mass ratio (q = 0.172) contact binary system, which indicates that it is at the late evolutionary stage of late-type tidal-locked binary stars. The masses of the primary star and secondary star are calculated to be

and

. The primary star has evolved from the zero-age main sequence, but it still appeared before the terminal-age main sequence, and the secondary star is even more evolved. Considering the mass ratio (

) obtained by spectroscopic observations, the mass of the close-in tertiary is estimated to be

. The period variations of the binary system are investigated for the first time. According to the observed–calculated (O−C) curve analysis, a continuous period increase at a rate of

is determined. The parabolic variation in the O−C curve may be part of a cyclic period of change, or the combined period of change of a parabolic variation and a cyclic one. More instances of minimum light are needed to confirm this. The presence of the tertiary component may play an important role in the formation and evolution of this binary system by drawing angular momentum from the central system during the pre-contact stage.
REVERBERATION MAPPING WITH INTERMEDIATE-BAND PHOTOMETRY: DETECTION OF BROAD-LINE Hα TIME LAGS FOR QUASARS AT 0.2 < z < 0.4
Authors: Jiang Linhua , Shen Yue , McGreer Ian D. , Fan Xiaohui , Morganson Eric , Windhorst Rogier A.
Published: February 2016

We present a reverberation mapping (RM) experiment that combines broad- and intermediate-band photometry; it is the first such attempt targeting 13 quasars at 0.2 < z < 0.9. The quasars were selected to have strong Hα or Hβ emission lines that are located in one of three intermediate bands (with FWHM around 200 Å) centered at 8045, 8505, and 9171 Å. The imaging observations were carried out in the intermediate bands and the broad i and z bands using the prime-focus imager 90Prime on the 2.3 m Bok telescope. Because of the large (∼1 deg2) field of view (FOV) of 90Prime, we included the 13 quasars within only five telescope pointings or fields. The five fields were repeatedly observed over 20–30 epochs that were unevenly distributed over a duration of 5–6 months. The combination of the broad- and intermediate-band photometry allows us to derive accurate light curves for both optical continuum emission (from the accretion disk) and line emission (from the broad-line region, or BLR). We detect Hα time lags between the continuum and line emission in six quasars. These quasars are at relatively low redshifts 0.2 < z < 0.4. The measured lags are consistent with the current BLR size–luminosity relation for Hβ at z < 0.3. While this experiment appears successful in detecting lags of the bright Hα line, further investigation is required to see if it can also be applied to the fainter Hβ line for quasars at higher redshifts. Finally we demonstrate that, by using a small telescope with a large FOV, intermediate-band photometric RM can be efficiently executed for a large sample of quasars at z > 0.2.
A UNIFIED FRAMEWORK FOR THE ORBITAL STRUCTURE OF BARS AND TRIAXIAL ELLIPSOIDS
Authors: Valluri Monica , Shen Juntai , Abbott Caleb , Debattista Victor P.
Published: February 2016

We examine a large random sample of orbits in two self-consistent simulations of N-body bars. Orbits in these bars are classified both visually and with a new automated orbit classification method based on frequency analysis. The well-known prograde x1 orbit family originates from the same parent orbit as the box orbits in stationary and rotating triaxial ellipsoids. However, only a small fraction of bar orbits (∼4%) have predominately prograde motion like their periodic parent orbit. Most bar orbits arising from the x1 orbit have little net angular momentum in the bar frame, making them equivalent to box orbits in rotating triaxial potentials. In these simulations a small fraction of bar orbits (∼7%) are long-axis tubes that behave exactly like those in triaxial ellipsoids: they are tipped about the intermediate axis owing to the Coriolis force, with the sense of tipping determined by the sign of their angular momentum about the long axis. No orbits parented by prograde periodic x2 orbits are found in the pure bar model, but a tiny population (∼2%) of short-axis tube orbits parented by retrograde x4 orbits are found. When a central point mass representing a supermassive black hole (SMBH) is grown adiabatically at the center of the bar, those orbits that lie in the immediate vicinity of the SMBH are transformed into precessing Keplerian orbits that belong to the same major families (short-axis tubes, long-axis tubes and boxes) occupying the bar at larger radii. During the growth of an SMBH, the inflow of mass and outward transport of angular momentum transform some x1 and long-axis tube orbits into prograde short-axis tubes. This study has important implications for future attempts to constrain the masses of SMBHs in barred galaxies using orbit-based methods like the Schwarzschild orbit superposition scheme and for understanding the observed features in barred galaxies.
A SYMMETRIC INNER CAVITY IN THE HD 141569A CIRCUMSTELLAR DISK
Authors: Mazoyer J. , Boccaletti A. , Choquet É. , Perrin M. D. , Pueyo L. , Augereau J.-C. , Lagrange A.-M. , Debes J. , Wolff S. G.
Published: February 2016

Some circumstellar disks, called transitional or hybrid disks, present characteristics of both protoplanetary disks (significant amount of gas) and debris disks (evolved structures around young main-sequence stars, composed of second generation dust, from collisions between planetesimals). Therefore, they are ideal astrophysical laboratories to witness the last stages of planet formation. The circumstellar disk around HD 141569A was intensively observed and resolved in the past from space, but also from the ground. However, the recent implementation of high contrast imaging systems has opened up new opportunities to re-analyze this object. We analyzed Gemini archival data from the Near-infrared Coronagraphic Imager obtained in 2011 in the H band, using several angular differential imaging techniques (classical ADI, LOCI, KLIP). These images reveal the complex structures of this disk with an unprecedented resolution. We also include archival Hubble Space Telescope images as an independent data set to confirm these findings. Using an analysis of the inner edge of the disk, we show that the inner disk is almost axisymmetrical. The measurement of an offset toward the east observed by previous authors is likely due to the fact that the eastern part of this disk is wider and more complex in substructure. Our precise reanalysis of the eastern side shows several structures, including a splitting of the disk and a small finger detached from the inner edge to the southeast. Finally, we find that the arc at 250 AU is unlikely to be a spiral, at least not at the inclination derived from the first ring, but instead could be interpreted as a third belt at a different inclination. If the very symmetrical inner disk edge is carved by a companion, the data presented here put additional constraints on its position. The observed very complex structures will be confirmed by the new generation of coronagraphic instrument (GPI, SPHERE). However, a full understanding of this system will require gas observations at millimetric wavelengths.
CALIBRATION OF THE MEARTH PHOTOMETRIC SYSTEM: OPTICAL MAGNITUDES AND PHOTOMETRIC METALLICITY ESTIMATES FOR 1802 NEARBY M-DWARFS
Authors: Dittmann Jason A. , Irwin Jonathan M. , Charbonneau David , Newton Elisabeth R.
Published: February 2016

The MEarth Project is a photometric survey systematically searching the smallest stars near the Sun for transiting rocky planets. Since 2008, MEarth has taken approximately two million images of 1844 stars suspected to be mid-to-late M dwarfs. We have augmented this survey by taking nightly exposures of photometric standard stars and have utilized this data to photometrically calibrate the MEarth system, identify photometric nights, and obtain an optical magnitude with 1.5% precision for each M dwarf system. Each optical magnitude is an average over many years of data, and therefore should be largely immune to stellar variability and flaring. We combine this with trigonometric distance measurements, spectroscopic metallicity measurements, and 2MASS infrared magnitude measurements in order to derive a color–magnitude–metallicity relation across the mid-to-late M dwarf spectral sequence that can reproduce spectroscopic metallicity determinations to a precision of 0.1 dex. We release optical magnitudes and metallicity estimates for 1567 M dwarfs, many of which did not have an accurate determination of either prior to this work. For an additional 277 stars without a trigonometric parallax, we provide an estimate of the distance, assuming solar neighborhood metallicity. We find that the median metallicity for a volume-limited sample of stars within 20 pc of the Sun is [Fe/H] = −0.03 ± 0.008, and that 29/565 of these stars have a metallicity of [Fe/H] = −0.5 or lower, similar to the low-metallicity distribution of nearby G dwarfs. When combined with the results of ongoing and future planet surveys targeting these objects, the metallicity estimates presented here will be important for assessing the significance of any putative planet–metallicity correlation.
MECHANICAL ENERGY FLUXES ASSOCIATED WITH SATURATED CORONAL HEATING IN M DWARFS: COMPARISON WITH PREDICTIONS OF A TURBULENT DYNAMO
Authors: Mullan D. J. , MacDonald J.
Published: February 2016

Empirically, the X-ray luminosity L
X from M dwarfs has been found to have an upper limit of about 0.2% of the bolometric flux L
bol. In the limit where magnetic fields in M dwarfs are generated in equipartition with convective motions, we use stellar models to calculate the energy flux of Alfvén waves F
A as a function of depth in the sub-surface convection zone. Since Alfvén waves have the optimal opportunity for wave modes to reach the corona, we suggest that F
A sets an upper limit on the mechanical flux F
mech which causes coronal heating. This suggestion accounts quantitatively for the “saturated” values of L
X/L
bol which have been reported empirically for M dwarfs.
A DISK-BASED DYNAMICAL CONSTRAINT ON THE MASS OF THE YOUNG BINARY DQ TAU
Authors: Czekala I. , Andrews S. M. , Torres G. , Jensen E. L. N. , Stassun K. G. , Wilner D. J. , Latham D. W.
Published: February 2016

We present new Atacama Large Millimeter/Submillimeter Array (ALMA) observations of CO J = 2−1 line emission from the DQ Tau circumbinary disk. These data are used to tomographically reconstruct the Keplerian disk velocity field in a forward-modeling inference framework, and thereby provide a dynamical constraint on the mass of the DQ Tau binary of

. Those results are compared with an updated and improved orbital solution for this double-lined system based on long-term monitoring of its stellar radial velocities. Both of these independent dynamical constraints on the binary mass are in excellent agreement: taken together, they demonstrate that the DQ Tau system mass is 1.21 ± 0.26 M
⊙ and that the disk and binary orbital planes are aligned within 3° (at 3σ confidence). The predictions of various theoretical models for pre-main-sequence stellar evolution are also consistent with these masses, though more detailed comparisons are difficult due to lingering uncertainties regarding the photospheric properties of the individual components. DQ Tau is the third, nearly equal-mass, double-lined spectroscopic binary with a circumbinary disk that has been dynamically “weighed” with these two independent techniques: all show consistent results, validating the overall accuracy of the disk-based approach and demonstrating that it can be robustly applied to large samples of young, single stars as ALMA ramps up to operations at full capacity.
STABILITY OF RIGIDLY ROTATING SUPERMASSIVE STARS AGAINST GRAVITATIONAL COLLAPSE
Authors: Shibata Masaru , Uchida Haruki , Sekiguchi Yu-ichiro
Published: February 2016

We revisit secular stability against quasi-radial collapse for rigidly rotating supermassive stars (SMSs) in general relativity. We suppose that the SMSs are in a nuclear-burning phase and can be modeled by polytropic equations of state with the polytropic index n
p slightly smaller than 3. The stability is determined in terms of the turning point method. We find a fitting formula of the stability condition for the plausible range of n
p (

) for SMSs. This condition reconfirms that while non-rotating SMSs with a mass of

–

may undergo a general relativistically induced quasi-radial collapse, rigidly rotating SMSs with a ratio of rotational to gravitational potential energy (β) of

are likely to be stable against collapse unless they are able to accrete ∼5 times more mass during the (relatively brief) hydrogen-burning phase of their evolution. We discuss the implications of our results.
A NUMERICAL SCHEME FOR SPECIAL RELATIVISTIC RADIATION MAGNETOHYDRODYNAMICS BASED ON SOLVING THE TIME-DEPENDENT RADIATIVE TRANSFER EQUATION
Authors: Ohsuga Ken , Takahashi Hiroyuki R.
Published: February 2016

We develop a numerical scheme for solving the equations of fully special relativistic, radiation magnetohydrodynamics (MHDs), in which the frequency-integrated, time-dependent radiation transfer equation is solved to calculate the specific intensity. The radiation energy density, the radiation flux, and the radiation stress tensor are obtained by the angular quadrature of the intensity. In the present method, conservation of total mass, momentum, and energy of the radiation magnetofluids is guaranteed. We treat not only the isotropic scattering but also the Thomson scattering. The numerical method of MHDs is the same as that of our previous work. The advection terms are explicitly solved, and the source terms, which describe the gas–radiation interaction, are implicitly integrated. Our code is suitable for massive parallel computing. We present that our code shows reasonable results in some numerical tests for propagating radiation and radiation hydrodynamics. Particularly, the correct solution is given even in the optically very thin or moderately thin regimes, and the special relativistic effects are nicely reproduced.
APODIZED PUPIL LYOT CORONAGRAPHS FOR ARBITRARY APERTURES. V. HYBRID SHAPED PUPIL DESIGNS FOR IMAGING EARTH-LIKE PLANETS WITH FUTURE SPACE OBSERVATORIES
Authors: N’Diaye Mamadou , Soummer Rémi , Pueyo Laurent , Carlotti Alexis , Stark Christopher C. , Perrin Marshall D.
Published: February 2016

We introduce a new class of solutions for Apodized Pupil Lyot Coronagraphs (APLC) with segmented aperture telescopes to remove broadband diffracted light from a star with a contrast level of 1010. These new coronagraphs provide a key advance to enabling direct imaging and spectroscopy of Earth twins with future large space missions. Building on shaped pupil (SP) apodization optimizations, our approach enables two-dimensional optimizations of the system to address any aperture features such as central obstruction, support structures, or segment gaps. We illustrate the technique with a design that could reach a 1010 contrast level at 34 mas for a 12 m segmented telescope over a 10% bandpass centered at a wavelength of

500 nm. These designs can be optimized specifically for the presence of a resolved star and, in our example, for stellar angular size up to 1.1 mas. This would allow one to probe the vicinity of Sun-like stars located beyond 4.4 pc, therefore, fully retiring this concern. If the fraction of stars with Earth-like planets is

, with 18% throughput, assuming a perfect, stable wavefront and considering photon noise only, 12.5 exo-Earth candidates could be detected around nearby stars with this design and a 12 m space telescope during a five-year mission with two years dedicated to exo-Earth detection (one total year of exposure time and another year of overheads). Our new hybrid APLC/SP solutions represent the first numerical solution of a coronagraph based on existing mask technologies and compatible with segmented apertures, and that can provide contrast compatible with detecting and studying Earth-like planets around nearby stars. They represent an important step forward toward enabling these science goals with future large space missions.
AN X-RAY SPECTRAL MODEL OF REPROCESSING BY SMOOTH AND CLUMPY MOLECULAR TORI IN ACTIVE GALACTIC NUCLEI WITH THE MONACO FRAMEWORK
Authors: Furui Shun’ya , Fukazawa Yasushi , Odaka Hirokazu , Kawaguchi Toshihiro , Ohno Masanori , Hayashi Kazuma
Published: February 2016

We construct an X-ray spectral model of reprocessing by a torus in an active galactic nucleus (AGN) with the Monte Carlo simulation framework MONACO. Two torus geometries of smooth and clumpy cases are considered and compared. In order to reproduce a Compton shoulder accurately, MONACO includes not only free electron scattering but also bound electron scattering. Raman and Rayleigh scattering are also treated, and scattering cross sections dependent on chemical states of hydrogen and helium are included. Doppler broadening by turbulence velocity can be implemented. Our model gives results consistent with other available models, such as MYTorus, except for differences due to different physical parameters and assumptions. We studied the dependence on torus parameters for a Compton shoulder, and found that a intensity ratio of a Compton shoulder to the line core mainly depends on column density, inclination angle, and metal abundance. For instance, an increase of metal abundance makes a Compton shoulder relatively weak. Also, the shape of a Compton shoulder depends on the column density. Furthermore, these dependences become different between smooth and clumpy cases. Then, we discuss the possibility of ASTRO-H/SXS spectroscopy of Compton shoulders in AGN reflection spectra.
SYSTEMATIC STUDIES OF SHOCK REVIVAL AND THE SUBSEQUENT EVOLUTIONS IN CORE-COLLAPSE SUPERNOVAE WITH PARAMETRIC PROGENITOR MODELS
Authors: Yamamoto Yu , Yamada Shoichi
Published: February 2016

We conducted one-dimensional and two-dimensional hydrodynamic simulations of post-shock revival evolutions in core-collapse supernovae, employing the simple neutrino light bulb approximation to produce explosions rather easily. In order to estimate the explosion energy, we took into proper account nuclear recombinations and fusions consistently with the equation of state for matter not in statistical equilibrium in general. The methodology is similar to our previous work, but is somehow improved. In this paper, we studied the influence of the progenitor structure on the dynamics systematically. In order to expedite our understanding of the systematics, we constructed six parametric progenitor models, which are different in masses of Fe iron core and Si+S layer, instead of employing realistic models provided by stellar evolution calculations, which are sometimes of stochastic nature as a function of stellar mass on the main sequence. We found that the explosion energy is tightly correlated with the mass accretion rate at shock revival irrespective of dimension and the progenitors with light iron cores but with rather high entropies, which have yet to be produced by realistic stellar evolution calculations, may reproduce the canonical values of explosion energy and nickel mass. The mass of the Si+S layer is also important in the mass accretion history after bounce, on the other hand; the higher mass accretion rates and resultant heavier cores tend to hamper strong explosions.
BAROCLINIC INSTABILITY IN THE SOLAR TACHOCLINE. II. THE EADY PROBLEM
Authors: Gilman Peter A.
Published: February 2016

We solve the nongeostrophic baroclinic instability problem for the tachocline for a continuous model with a constant vertical rotation gradient (the Eady problem), using power series generated by the Frobenius method. The results confirm and greatly extend those from a previous two-layer model. For effective gravity G independent of height, growth rates and ranges of unstable longitudinal wavenumbers m and latitudes increase with decreasing G. As with the two-layer model, the overshoot tachocline is much more unstable than the radiative tachocline. The e-folding growth times range from as short as 10 days to as long as several years, depending on latitude, G, and wavenumber. For a more realistic effective gravity that decreases linearly from the radiative interior to near zero at the top of the tachocline, we find that only m = 1, 2 modes are unstable, with growth rates somewhat larger than for constant G, with the same value as at the bottom of the tachocline. All results are the same whether we assume that the vertical velocity or the perturbation pressure is zero at the top of the layer; this is a direct consquence of not employing the geostrophic assumption for perturbations. We explain most of the properties of the instability in terms of the Rossby deformation radius. We discuss further improvements in the realism of the model, particularly adding toroidal fields that vary in height, and including latitudinal gradients of both rotation and toroidal fields.
DOES THE INTERMEDIATE-MASS BLACK HOLE IN LEDA 87300 (RGG 118) FOLLOW THE NEAR-QUADRATIC Mbh–Mspheroid RELATION?
Authors: Graham Alister W. , Ciambur Bogdan C. , Soria Roberto
Published: February 2016

The mass scaling relation between supermassive black holes and their host spheroids has previously been described by a quadratic or steeper relation at low masses (105 < M
bh/M
⊙ ≲ 107). How this extends into the realm of intermediate-mass black holes (102 < M
bh/M
⊙ < 105) is not yet clear, although for the barred Sm galaxy LEDA 87300, Baldassare et al. recently reported a nominal virial mass of M
bh = 5 × 104 M
⊙ residing in a “spheroid” of stellar mass equal to 6.3 × 108 M
⊙. We point out, for the first time, that LEDA 87300 therefore appears to reside on the near-quadratic M
bh–M
sph,* relation. However, Baldassare et al. modeled the bulge and bar as the single spheroidal component of this galaxy. Here we perform a 3-component bulge+bar+disk decomposition and find a bulge luminosity which is 7.7 times fainter than the published “bulge” luminosity. After correcting for dust, we find that M
bulge = 0.9 × 108 M
⊙ and M
bulge/M
disk = 0.04—which is now in accord with ratios typically found in Scd–Sm galaxies. We go on to discuss slight revisions to the stellar velocity dispersion (40 ± 11 km s−1) and black hole mass (

) and show that LEDA 87300 remains consistent with the M
bh–σ relation, and also the near-quadratic M
bh–M
sph,* relation when using the reduced bulge mass. LEDA 87300 therefore offers the first support for the rapid but regulated (near-quadratic) growth of black holes, relative to their host bulge/spheroid, extending into the domain of intermediate-mass black holes.