bluuebunny/crossref_metadata_2025 huggingface dataset:
Flow Hydrodynamics across Open Channel Flows with Riparian Zones: Implications for Riverbank Stability
Authors: Liu Da , Valyrakis Manousos , Williams Richard
Published: September 2017

Riverbank vegetation is of high importance both for preserving the form (morphology) and function (ecology) of natural river systems. Revegetation of riverbanks is commonly used as a means of stream rehabilitation and management of bank instability and erosion. In this experimental study, the effect of different riverbank vegetation densities on flow hydrodynamics across the channel, including the riparian zone, are reported and discussed. The configuration of vegetation elements follows either linear or staggered arrangements as vegetation density is progressively increased, within a representative range of vegetation densities found in nature. Hydrodynamic measurements including mean streamwise velocity and turbulent intensity flow profiles are recorded via acoustic Doppler velocimetry (ADV)—both at the main channel and within the riverbank. These results show that for the main channel and the toe of riverbank, turbulence intensity for the low densities (λ ≈ 0 to 0.12 m−1) can increase up to 40% compared the case of high densities (λ = 0.94 to 1.9 m−1). Further analysis of these data allowed the estimation of bed-shear stresses, demonstrating 84% and 23% increase at the main channel and near the toe region, for increasing densities (λ = 0 to 1.9 m−1). Quantifying these hydrodynamic effects is important for assessing the contribution of physically representative ranges of riparian vegetation densities on hydrogeomorphologic feedback.
Investigating Hydrochemical Groundwater Processes in an Inland Agricultural Area with Limited Data: A Clustering Approach
Authors: Wu Xin , Zheng Yi , Zhang Juan , Wu Bin , Wang Sai , Tian Yong , Li Jinguo , Meng Xue
Published: September 2017

Groundwater chemistry data are normally scarce in remote inland areas. Effective statistical approaches are highly desired to extract important information about hydrochemical processes from the limited data. This study applied a clustering approach based on the Gaussian Mixture Model (GMM) to a hydrochemical dataset of groundwater collected in the middle Heihe River Basin (HRB) of northwestern China. Independent hydrological data were introduced to examine whether the clustering results led to an appropriate interpretation on the hydrochemical processes. The main findings include the following. First, in the middle HRB, although groundwater chemistry reflects primarily a natural salinization process, there are evidence for significant anthropogenic influence such as irrigation and fertilization. Second, the regional hydrological cycle, particularly surface water-groundwater interaction, has a profound and spatially variable impact on groundwater chemistry. Third, the interaction between the regional agricultural development and the groundwater quality is complicated. Overall, this study demonstrates that the GMM clustering can effectively analyze hydrochemical datasets and that these clustering results can provide insights into hydrochemical processes, even with a limited number of observations. The clustering approach introduced in this study represents a cost-effective way to investigate groundwater chemistry in remote inland areas where groundwater monitoring is difficult and costly.
Cost-effectiveness of antibiotic treatment of uncomplicated urinary tract infection in women: a comparison of four antibiotics
Authors: Sadler Susannah , Holmes Michael , Ren Shijie , Holden Stephen , Jha Swati , Thokala Praveen
Published: September 2017

Background

Urinary tract infections (UTIs) are one of the most common reasons for women to attend primary care. There are four different antibiotics currently recommended in England for treatment of uncomplicated UTI but little evidence on their comparative cost-effectiveness.

Aim

To assess the relative cost-effectiveness of the four antibiotics currently recommended in England for treatment of uncomplicated UTI in adult women.

Design & setting

A cost-effectiveness model in adult women with signs and symptoms of uncomplicated UTI in primary care in England treated with fosfomycin, nitrofurantoin, pivmecillinam, or trimethoprim.

Method

A decision tree economic model of the treatment pathway encompassed up to two rounds of treatment, accounting for different resistance levels. End points included recovery, persistence, pyelonephritis, and/or hospitalisation. Prescription, primary and secondary care treatment, and diagnostic testing costs were aggregated. Cost-effectiveness was assessed as cost per UTI resolved.

Results

Trimethoprim 200 mg twice daily (for 3 or 7 days) was estimated to be the most cost-effective treatment (£70 per UTI resolved) when resistance was <30%. However, if resistance to trimethoprim was ≥30%, fosfomycin 3 g once became more cost-effective; at resistance levels of ≥35% for trimethoprim, both fosfomycin 3 g once and nitrofurantoin 100 mg twice daily for 7 days were shown to be more cost-effective.

Conclusion

Knowing local resistance levels is key to effective and cost-effective empirical prescribing. Recent estimates of trimethoprim resistance rates are close to 50%, in which case a single 3 g dose of fosfomycin is likely to be the most cost-effective treatment option.
Cancer suspicion in general practice, urgent referral, and time to diagnosis: a population-based GP survey nested within a feasibility study using information technology to flag-up patients with symptoms of colorectal cancer
Authors: Kidney Elaine , Greenfield Sheila , Berkman Lindy , Dowswell George , Hamilton William , Wood Sally , Marshall Tom
Published: September 2017

Background

Patients with symptoms of possible colorectal cancer are not always referred for investigation.

Aim

To ascertain barriers and facilitators to GP referral of patients meeting the National Institute for Health and Care Excellence (NICE) guidelines for urgent referral for suspected colorectal cancer.

Design & setting

Qualitative study in the context of a feasibility study using information technology in GP practices to flag-up patients meeting urgent referral criteria for colorectal cancer.

Method

Semi-structured interview with 18 GPs and 12 practice managers, focusing on early detection of colorectal cancer, issues in the use of information technology to identify patients and GP referral of these patients for further investigation were audiotaped, transcribed verbatim, and analysed according to emergent themes.

Results

There were two main themes: wide variation in willingness to refer and uncertainty about whether to refer; and barriers to referral. Three key messages emerged: there was a desire to avoid over-referral, lack of knowledge of guidelines, and the use of individually-derived decision rules for further investigation or referral of symptoms. Some GPs were unaware that iron deficiency anaemia or persistent diarrhoea are urgent referral criteria. Alternatives to urgent referral included undertaking no investigations, trials of iron therapy, use of faecal occult blood tests (FOBt) and non-urgent referral. In minority ethnic groups (South Asians) anaemia was often accepted as normal.

Concerns about over-referral were linked to financial pressures and perceived criticism by healthcare commissioners, and a reluctance to scare patients by discussing suspected cancer.

Conclusion

GPs’ lack of awareness of referral guidelines and concerns about over-referral are barriers to early diagnosis of colorectal cancer.
Worldwide Experiences with Assisted Peritoneal Dialysis
Authors: Giuliani Anna , Karopadi Akash Nayak , Prieto-Velasco Mario , Manani Sabrina Milan , Crepaldi Carlo , Ronco Claudio
Published: September 2017

End-stage renal disease (ESRD) is common in the elderly population, and renal replacement therapy (RRT) is often required. However, in this particular subgroup of patients, the choice between hemodialysis (HD) and peritoneal dialysis (PD) is often not an easy decision to make. Published literature has adequately demonstrated that PD prevalence is significantly less than HD across all patient age groups despite several advantages. We also know that elderly patients are less likely to complete a PD assessment, due to both medical and social barriers. Additionally, elderly patients are often reluctant to go ahead with PD despite being eligible PD candidates, mainly due to the fear of performing self-therapy. Recently, many new assisted PD (asPD) programs have cropped up in several countries. The main aim of these programs is to overcome barriers to PD and to promote PD utilization among elderly and non-self-sufficient patients. Although asPD has proven to be associated with good clinical results, there still remain concerns about its greater use. In this review, we will first describe an ideal asPD model and then enumerate examples of strategies and outcomes associated with successful asPD programs worldwide.
Prevalence and Characteristics of Patients with Severe Hyperacusis among Patients Seen in a Tinnitus and Hyperacusis Clinic
Authors: Aazh Hashir , Moore Brian C. J.
Published: September 2017

Purpose:The purpose was to assess the proportion of patients seeking help for tinnitus and/or hyperacusis who have severe hyperacusis and to examine factors associated with severe hyperacusis.Research Design:This was a retrospective cross-sectional study based on 362 consecutive
patients who attended a National Health Service audiology clinic for tinnitus and/or hyperacusis rehabilitation and for whom uncomfortable loudness levels (ULLs) had been measured. The criterion for severe hyperacusis was taken as a ULL of 30 dB HL or less for at least one of the measured
frequencies for at least one ear.Results:Thirteen patients had severe hyperacusis, and eight of those had normal hearing. The lowest average ULL across frequencies was 28 dB HL. The difference in average ULLs between ears was 5 dB or less for nine patients. The range of ULLs across
frequencies was between 5 and 60 dB, ULLs often being lowest at 8 kHz. Eleven patients had tinnitus, eight had otological abnormalities, twelve had mental health problems, and six were taking antidepressants.Conclusions:Severe hyperacusis is characterized by low ULLs for specific frequencies
and no or mild hearing loss. Given the high incidence of tinnitus, otological abnormalities, and mental health problems, the management of patients with severe hyperacusis should involve otologists and psychiatrists in addition to audiologists.
Are there differences between partial and total periodontal examination of the mouth?
Authors: Coelho Renata S , Gusmao Estela S , Siqueira Rafael Amorim Cavalcanti de , Donos Nikos , Vajgel Bruna Carvalho Farias , Cimões Renata
Published: September 2017

Background: Diagnosis of periodontal disease for epidemiologic survey is difficult due to complexity of periodontal exam. The aim of this study was  to compare data from a full-mouth examination and a partial-mouth examination, observing the agreement between both methods of presenting the Community Periodontal Index (CPI).

Methods and Findings: The population comprised of male and female subjects, aged 18 years and over, attending public health centers in the city of Recife, Brazil. A total of 505 patients participated in this study. Each participant completed a form and underwent periodontal examination. Firstly, for each tooth present one of the periodontal conditions was determined: periodontal health, gingival bleeding, dental calculus, shallow periodontal pockets and deep periodontal pockets, according to CPI. Finally, partial data (10 index teeth) was recorded derived from the total version of CPI. Bivariate analysis of frequencies and means was performed. Mc Nemar test was used to calculate the level of statistical significance of the association tested. There are significant statistical differences between partial and full-mouth examination (p<0.001). According to gender, men classified as score 1 presented the same prevalence in both methods; partial recording overestimated 0.2% of women classified as score 1; percentile difference among men was higher for subjects classified as score 0. Among subjects with at least one tooth with deep periodontal pocket, percentile difference between different approaches was higher among elders (60 years and over).

Conclusions: Considering the variable age, the smaller amount of lost information refers to periodontal pockets in individuals aged 18 to 30 years of age. In older individuals classified as periodontally healthy and with gingival bleeding no loss of information was observed. Partial examination of the mouth underestimated the presence of periodontal pockets and overestimated the presence of calculus and bleeding. A high concordance between the partial and total examination was observed.
First Spectropolarimetric Measurement of a Brown Dwarf Magnetic Field in Molecular Bands
Authors: Kuzmychov Oleksii , Berdyugina Svetlana V. , Harrington David M.
Published: September 2017

We present the first measurements of the surface magnetic field of a late-M dwarf, LSR J1835+3259, with the help of the full-Stokes spectropolarimetry in the bands of diatomic molecules. Our measurements at different rotational phases of a dwarf yielded one 5σ and two 3σ magnetic field detections. The observational data have been obtained with the LRISp polarimeter at the Keck observatory on 2012 August 22 and 23. These data have been compared against synthetic full-Stokes spectra in the bands of the molecules CrH, FeH, and TiO, which have been calculated for a range of the stellar parameters and magnetic field strengths. Making use of χ
2-minimization and maximum likelihood estimation, we determine the net magnetic field strength B (and not flux Bf) of LSR J1835+3259 to ∼5 kG with the help of the Paschen–Back effect in the CrH lines. Our measurements at different rotational phases suggest that the dwarf’s surface might be covered with strong small-scale magnetic fields. In addition, recent findings of the dwarf’s hydrogen emission and the Stokes V signal from the lower chromosphere indicate that its surface magnetic field might be changing rapidly giving rise to flare activity, similar to young dMe dwarfs. We substantiate the substellar origin of LSR J1835+3259 by making use of our own data as well as the photometric data from the all-sky surveys 2MASS and WISE.
The Circumestellar Disk of the B0 Protostar Powering the HH 80-81 Radio Jet
Authors: Girart J. M. , Estalella R. , Fernández-López M. , Curiel S. , Frau P , Galvan-Madrid R. , Rao R. , Busquet G. , Juárez C.
Published: September 2017

We present subarcsecond angular resolution observations carried out with the Submillimeter Array (SMA) at 880 μm centered at the B0-type protostar GGD27 MM1, the driving source of the parsec scale HH 80-81 jet. We constrain its polarized continuum emission to ≲0.8% at this wavelength. Its submillimeter spectrum is dominated by sulfur-bearing species tracing a rotating-disk-like structure (SO and SO2 isotopologues mainly), but also shows HCN-bearing and CH3OH lines, which trace the disk and the outflow cavity walls excavated by the HH 80-81 jet. The presence of many sulfurated lines could indicate the presence of shocked gas at the disk’s centrifugal barrier or that MM1 is a hot core at an evolved stage. The resolved SO2 emission traces the disk kinematics very well and we fit the SMA observations using a thin-disk Keplerian model, which gives the inclination (47°), the inner (≲170 au) and outer (∼950–1300 au) radii, and the disk’s rotation velocity (3.4 km s−1 at a putative radius of 1700 au). We roughly estimate a protostellar dynamical mass of 4–18

. MM2 and WMC cores show, comparatively, an almost empty spectra, suggesting that they are associated with extended emission detected in previous low-angular resolution observations, and therefore indicating youth (MM2) or the presence of a less massive object (WMC).
Turbulent Magnetic Relaxation in Pulsar Wind Nebulae
Authors: Zrake Jonathan , Arons Jonathan
Published: September 2017

We present a model for magnetic energy dissipation in a pulsar wind nebula. A better understanding of this process is required to assess the likelihood that certain astrophysical transients may be powered by the spin-down of a “millisecond magnetar.” Examples include superluminous supernovae, gamma-ray bursts, and anticipated electromagnetic counterparts to gravitational wave detections of binary neutron star coalescence. Our model leverages recent progress in the theory of turbulent magnetic relaxation to specify a dissipative closure of the stationary magnetohydrodynamic (MHD) wind equations, yielding predictions of the magnetic energy dissipation rate throughout the nebula. Synchrotron losses are self-consistently treated. To demonstrate the model’s efficacy, we show that it can reproduce many features of the Crab Nebula, including its expansion speed, radiative efficiency, peak photon energy, and mean magnetic field strength. Unlike ideal MHD models of the Crab (which lead to the so-called σ-problem), our model accounts for the transition from ultra to weakly magnetized plasma flow and for the associated heating of relativistic electrons. We discuss how the predicted heating rates may be utilized to improve upon models of particle transport and acceleration in pulsar wind nebulae. We also discuss implications for the Crab Nebula’s γ-ray flares, and point out potential modifications to models of astrophysical transients invoking the spin-down of a millisecond magnetar.
iPTF17cw: An Engine-driven Supernova Candidate Discovered Independent of a Gamma-Ray Trigger
Authors: Corsi A. , Cenko S. B. , Kasliwal M. M. , Quimby R. , Kulkarni S. R. , Frail D. A. , Goldstein A. M. , Blagorodnova N. , Connaughton V. , Perley D. A. , Singer L. P. , Copperwheat C. M. , Fremling C. , Kupfer T. , Piascik A. S. , Steele I. A. , Taddia F. , Vedantham H. , Kutyrev A. , Palliyaguru N. T. , Roberts O. , Sollerman J. , Troja E. , Veilleux S.
Published: September 2017

We present the discovery, classification, and radio-to-X-ray follow-up observations of iPTF17cw, a broad-lined (BL) type Ic supernova (SN) discovered by the intermediate Palomar Transient Factory (iPTF). Although it is unrelated to the gravitational wave trigger, this SN was discovered as a happy by-product of the extensive observational campaign dedicated to the follow-up of Advanced LIGO event GW 170104. The spectroscopic properties and inferred peak bolometric luminosity of iPTF17cw are most similar to the gamma-ray-burst (GRB)-associated SN, SN 1998bw, while the shape of the r-band light curve is most similar to that of the relativistic SN, SN 2009bb. Karl G. Jansky Very Large Array (VLA) observations of the iPTF17cw field reveal a radio counterpart ≈10 times less luminous than SN 1998bw, and with a peak radio luminosity comparable to that of SN 2006aj/GRB 060218 and SN 2010bh/GRB 100316D. Our radio observations of iPTF17cw imply a relativistically expanding outflow. However, further late-time observations with the VLA in its most extended configuration are needed to confirm fading of the iPTF17cw radio counterpart at all frequencies. X-ray observations carried out with Chandra reveal the presence of an X-ray counterpart with a luminosity similar to that of SN 2010bh/GRB 100316D. Searching the Fermi catalog for possible γ-rays reveals that GRB 161228B is spatially and temporally compatible with iPTF17cw. The similarity to SN 1998bw and SN 2009bb, the radio and X-ray detections, and the potential association with GRB 161228B all point to iPTF17cw being a new candidate member of the rare sample of optically discovered engine-driven BL-Ic SNe associated with relativistic ejecta.
The Mira-Titan Universe. II. Matter Power Spectrum Emulation
Authors: Lawrence Earl , Heitmann Katrin , Kwan Juliana , Upadhye Amol , Bingham Derek , Habib Salman , Higdon David , Pope Adrian , Finkel Hal , Frontiere Nicholas
Published: September 2017

We introduce a new cosmic emulator for the matter power spectrum covering eight cosmological parameters. Targeted at optical surveys, the emulator provides accurate predictions out to a wavenumber

Mpc−1 and redshift

. In addition to covering the standard set of ΛCDM parameters, massive neutrinos and a dynamical dark energy of state are included. The emulator is built on a sample set of 36 cosmological models, carefully chosen to provide accurate predictions over the wide and large parameter space. For each model, we have performed a high-resolution simulation, augmented with 16 medium-resolution simulations and TimeRG perturbation theory results to provide accurate coverage over a wide k-range; the data set generated as part of this project is more than 1.2Pbytes. With the current set of simulated models, we achieve an accuracy of approximately 4%. Because the sampling approach used here has established convergence and error-control properties, follow-up results with more than a hundred cosmological models will soon achieve

accuracy. We compare our approach with other prediction schemes that are based on halo model ideas and remapping approaches. The new emulator code is publicly available.
Shocks and Spatially Offset Active Galactic Nuclei Produce Velocity Offsets in Emission Lines
Authors: Comerford Julia M. , Barrows R. Scott , Greene Jenny E. , Pooley David
Published: September 2017

While 2% of active galactic nuclei (AGNs) exhibit narrow emission lines with line-of-sight velocities that are significantly offset from the velocity of the host galaxy’s stars, the nature of these velocity offsets is unknown. We investigate this question with Chandra/ACIS and Hubble Space Telescope/Wide Field Camera 3 observations of seven velocity-offset AGNs at

; all seven galaxies have a central AGN, but a peak in emission that is spatially offset by <kpc from the host galaxy’s stellar centroid. These spatial offsets are responsible for the observed velocity offsets and are due to shocks, either from AGN outflows (in four galaxies) or gas inflowing along a bar (in three galaxies). We compare our results with a velocity-offset AGN whose velocity offset originates from a spatially offset AGN in a galaxy merger. The optical line flux ratios of the offset AGN are consistent with pure photoionization, while the optical line flux ratios of our sample are consistent with contributions from photoionization and shocks. We conclude that these optical line flux ratios could be efficient for separating velocity-offset AGNs into subgroups of offset AGNs—which are important for studies of AGN fueling in galaxy mergers—and central AGNs with shocks, where the outflows are biased toward the most energetic outflows that are the strongest drivers of feedback.
Blueberry Galaxies: The Lowest Mass Young Starbursts
Authors: Yang Huan , Malhotra Sangeeta , Rhoads James E. , Wang Junxian
Published: September 2017

Searching for extreme emission line galaxies allows us to find low-mass metal-poor galaxies that are good analogs of high redshift Lyα emitting galaxies. These low-mass extreme emission line galaxies are also potential Lyman-continuum leakers. Finding them at very low redshifts (

) allows us to be sensitive to even lower stellar masses and metallicities. We report on a sample of extreme emission line galaxies at

(blueberry galaxies). We selected them from SDSS broadband images on the basis of their broadband colors and studied their properties with MMT spectroscopy. From the entire SDSS DR12 photometric catalog, we found 51 photometric candidates. We spectroscopically confirm 40 as blueberry galaxies. (An additional seven candidates are contaminants, and four remain without spectra.) These blueberries are dwarf starburst galaxies with very small sizes (<1 kpc) and very high ionization ([O iii]/[O ii] ∼ 10–60). They also have some of the lowest stellar masses (

) and lowest metallicities (

) of starburst galaxies. Thus, they are small counterparts to green pea galaxies and high redshift Lyα emitting galaxies.
Do Low Surface Brightness Galaxies Host Stellar Bars?
Authors: Cervantes Sodi Bernardo , Sánchez García Osbaldo
Published: September 2017

With the aim of assessing if low surface brightness galaxies host stellar bars and by studying the dependence of the occurrence of bars as a function of surface brightness, we use the Galaxy Zoo 2 data set to construct a large volume-limited sample of galaxies and then segregate these galaxies as having low or high surface brightness in terms of their central surface brightness. We find that the fraction of low surface brightness galaxies hosting strong bars is systematically lower than that found for high surface brightness galaxies. The dependence of the bar fraction on the central surface brightness is mostly driven by a correlation of the surface brightness with the spin and the gas richness of the galaxies, showing only a minor dependence on the surface brightness. We also find that the length of the bars is strongly dependent on the surface brightness, and although some of this dependence is attributed to the gas content, even at a fixed gas-to-stellar mass ratio, high surface brightness galaxies host longer bars than their low surface brightness counterparts, which we attribute to an anticorrelation of the surface brightness with the spin.
Two-dimensional Radiative Magnetohydrodynamic Simulations of Partial Ionization in the Chromosphere. II. Dynamics and Energetics of the Low Solar Atmosphere
Authors: Martínez-Sykora Juan , Pontieu Bart De , Carlsson Mats , Hansteen Viggo H. , Nóbrega-Siverio Daniel , Gudiksen Boris V.
Published: September 2017

We investigate the effects of interactions between ions and neutrals on the chromosphere and overlying corona using 2.5D radiative MHD simulations with the Bifrost code. We have extended the code capabilities implementing ion–neutral interaction effects using the generalized Ohm’s law, i.e., we include the Hall term and the ambipolar diffusion (Pedersen dissipation) in the induction equation. Our models span from the upper convection zone to the corona, with the photosphere, chromosphere, and transition region partially ionized. Our simulations reveal that the interactions between ionized particles and neutral particles have important consequences for the magnetothermodynamics of these modeled layers: (1) ambipolar diffusion increases the temperature in the chromosphere; (2) sporadically the horizontal magnetic field in the photosphere is diffused into the chromosphere, due to the large ambipolar diffusion; (3) ambipolar diffusion concentrates electrical currents, leading to more violent jets and reconnection processes, resulting in (3a) the formation of longer and faster spicules, (3b) heating of plasma during the spicule evolution, and (3c) decoupling of the plasma and magnetic field in spicules. Our results indicate that ambipolar diffusion is a critical ingredient for understanding the magnetothermodynamic properties in the chromosphere and transition region. The numerical simulations have been made publicly available, similar to previous Bifrost simulations. This will allow the community to study realistic numerical simulations with a wider range of magnetic field configurations and physics modules than previously possible.
New ZZ Ceti Stars from the LAMOST Survey
Authors: Su Jie , Fu Jianning , Lin Guifang , Chen Fangfang , Khokhuntod Pongsak , Li Chunqian
Published: September 2017

The spectroscopic sky survey carried out by the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) provides the largest stellar spectra library in the world to date. A large number of new DA white dwarfs had been identified based on the LAMOST spectra. The effective temperature (

) and surface gravity (

) of most DA white dwarfs were determined and published in the catalogs. We selected ZZ Ceti candidates from the published catalogs by considering whether their

are situated in the ZZ Ceti instability strip. The follow-up time-series photometric observations for the candidates were performed in 2015 and 2016. Four stars: LAMOST J004628.31+343319.90, LAMOST J062159.49+252335.9, LAMOST J010302.46+433756.2, and LAMOST J013033.90+273757.9 are finally confirmed to be new ZZ Ceti stars. They show dominant peaks with amplitudes rising above the 99.9% confidence level in the amplitude spectra. As LAMOST J004628.31+343319.90 has an estimated mass of ∼0.40

, and LAMOST J013033.90+273757.9 has a mass of ∼0.45

derived from their

values, these two stars are inferred to be potential helium-core white dwarfs.
Aerosol Properties of the Atmospheres of Extrasolar Giant Planets
Authors: Lavvas P. , Koskinen T.
Published: September 2017

We use a model of aerosol microphysics to investigate the impact of high-altitude photochemical aerosols on the transmission spectra and atmospheric properties of close-in exoplanets, such as HD 209458 b and HD 189733 b. The results depend strongly on the temperature profiles in the middle and upper atmospheres, which are poorly understood. Nevertheless, our model of HD 189733 b, based on the most recently inferred temperature profiles, produces an aerosol distribution that matches the observed transmission spectrum. We argue that the hotter temperature of HD 209458 b inhibits the production of high-altitude aerosols and leads to the appearance of a clearer atmosphere than on HD 189733 b. The aerosol distribution also depends on the particle composition, photochemical production, and atmospheric mixing. Due to degeneracies among these inputs, current data cannot constrain the aerosol properties in detail. Instead, our work highlights the role of different factors in controlling the aerosol distribution that will prove useful in understanding different observations, including those from future missions. For the atmospheric mixing efficiency suggested by general circulation models, we find that the aerosol particles are small (∼nm) and probably spherical. We further conclude that a composition based on complex hydrocarbons (soots) is the most likely candidate to survive the high temperatures in hot-Jupiter atmospheres. Such particles would have a significant impact on the energy balance of HD 189733 b’s atmosphere and should be incorporated in future studies of atmospheric structure. We also evaluate the contribution of external sources to photochemical aerosol formation and find that their spectral signature is not consistent with observations.
Fully Kinetic versus Reduced-kinetic Modeling of Collisionless Plasma Turbulence
Authors: Grošelj Daniel , Cerri Silvio S. , Navarro Alejandro Bañón , Willmott Christopher , Told Daniel , Loureiro Nuno F. , Califano Francesco , Jenko Frank
Published: September 2017

We report the results of a direct comparison between different kinetic models of collisionless plasma turbulence in two spatial dimensions. The models considered include a first-principles fully kinetic (FK) description, two widely used reduced models (gyrokinetic (GK) and hybrid-kinetic (HK) with fluid electrons), and a novel reduced gyrokinetic approach (KREHM). Two different ion beta (

) regimes are considered: 0.1 and 0.5. For

, good agreement between the GK and FK models is found at scales ranging from the ion to the electron gyroradius, thus providing firm evidence for a kinetic Alfvén cascade scenario. In the same range, the HK model produces shallower spectral slopes, presumably due to the lack of electron Landau damping. For

, a detailed analysis of spectral ratios reveals a slight disagreement between the GK and FK descriptions at kinetic scales, even though kinetic Alfvén fluctuations likely still play a significant role. The discrepancy can be traced back to scales above the ion gyroradius, where the FK and HK results seem to suggest the presence of fast magnetosonic and ion Bernstein modes in both plasma beta regimes, but with a more notable deviation from GK in the low-beta case. The identified practical limits and strengths of reduced-kinetic approximations, compared here against the FK model on a case-by-case basis, may provide valuable insight into the main kinetic effects at play in turbulent collisionless plasmas, such as the solar wind.
A Multiwavelength Study of Nearby Millisecond Pulsar PSR J1400−1431: Improved Astrometry and an Optical Detection of Its Cool White Dwarf Companion
Authors: Swiggum J. K. , Kaplan D. L. , McLaughlin M. A. , Lorimer D. R. , Bogdanov S. , Ray P. S. , Lynch R. , Gentile P. , Rosen R. , Heatherly S. A. , Barlow B. N. , Hegedus R. J. , Soto A. Vasquez , Clancy P. , Kondratiev V. I. , Stovall K. , Istrate A. , Penprase B. , Bellm E. C.
Published: September 2017

In 2012, five high-school students involved in the Pulsar Search Collaboratory discovered the millisecond pulsar (MSP) PSR J1400−1431, and initial timing parameters were published in Rosen et al. a year later. Since then, we have obtained a phase-connected timing solution spanning five years, resolving a significant position discrepancy and measuring

, proper motion, parallax, and a monotonic slope in dispersion measure over time. Due to PSR J1400−1431’s proximity and significant proper motion, we use the Shklovskii effect and other priors to determine a 95% confidence interval for PSR J1400−1431’s distance,

pc. With an improved timing position, we present the first detection of the pulsar’s low-mass white dwarf (WD) companion using the Goodman Spectrograph on the 4.1 m SOAR telescope. Deeper imaging suggests that it is a cool DA-type WD with

K and

. We show a convincing association between PSR J1400−1431 and a γ-ray point source, 3FGL J1400.5−1437, but only weak (3.3σ) evidence of pulsations after folding γ-ray photons using our radio timing model. We detect an X-ray counterpart with XMM-Newton, but the measured X-ray luminosity (1×1029 erg s−1) makes PSR J1400−1431 the least X-ray luminous rotation-powered MSP detected to date. Together, our findings present a consistent picture of a nearby (

pc) MSP in a 9.5-day orbit around a cool ∼0.3 M
⊙ WD companion, with orbital inclination

.
Fast Molecular Cloud Destruction Requires Fast Cloud Formation
Authors: Mac Low Mordecai-Mark , Burkert Andreas , Ibáñez-Mejía Juan C.
Published: September 2017

A large fraction of the gas in the Galaxy is cold, dense, and molecular. If all this gas collapsed under the influence of gravity and formed stars in a local free-fall time, the star formation rate in the Galaxy would exceed that observed by more than an order of magnitude. Other star-forming galaxies behave similarly. Yet, observations and simulations both suggest that the molecular gas is indeed gravitationally collapsing, albeit hierarchically. Prompt stellar feedback offers a potential solution to the low observed star formation rate if it quickly disrupts star-forming clouds during gravitational collapse. However, this requires that molecular clouds must be short-lived objects, raising the question of how so much gas can be observed in the molecular phase. This can occur only if molecular clouds form as quickly as they are destroyed, maintaining a global equilibrium fraction of dense gas. We therefore examine cloud formation timescales. We first demonstrate that supernova and superbubble sweeping cannot produce dense gas at the rate required to match the cloud destruction rate. On the other hand, Toomre gravitational instability can reach the required production rate. We thus argue that, although dense, star-forming gas may last only around a single global free-fall time; the dense gas in star-forming galaxies can globally exist in a state of dynamic equilibrium between formation by gravitational instability and disruption by stellar feedback. At redshift z ≳ 2, the Toomre instability timescale decreases, resulting in a prediction of higher molecular gas fractions at early times, in agreement with the observations.
Probing Large-scale Coherence between Spitzer IR and Chandra X-Ray Source-subtracted Cosmic Backgrounds
Authors: Cappelluti N. , Arendt R. , Kashlinsky A. , Li Y. , Hasinger G. , Helgason K. , Urry M. , Natarajan P. , Finoguenov A.
Published: September 2017

We present new measurements of the large-scale clustering component of the cross-power spectra of the source-subtracted Spitzer-IRAC cosmic infrared background and Chandra-ACIS cosmic X-ray background surface brightness fluctuations Our investigation uses data from the Chandra Deep Field South, Hubble Deep Field North, Extended Groth Strip/AEGIS field, and UDS/SXDF surveys, comprising 1160 Spitzer hours and ∼12 Ms of Chandra data collected over a total area of 0.3 deg2. We report the first (>5σ) detection of a cross-power signal on large angular scales >20″ between [0.5–2] keV and the 3.6 and 4.5 μm bands, at ∼5σ and 6.3σ significance, respectively. The correlation with harder X-ray bands is marginally significant. Comparing the new observations with existing models for the contribution of the known unmasked source population at z < 7, we find an excess of about an order of magnitude at 5σ confidence. We discuss possible interpretations for the origin of this excess in terms of the contribution from accreting early black holes (BHs), including both direct collapse BHs and primordial BHs, as well as from scattering in the interstellar medium and intra-halo light.
Montée en puissance de la Chine : l’Europe et les États-Unis peuvent-ils coopérer ?
Authors: Le Corre Philippe
Published: September 2017

Cet article aborde la montée en puissance de la Chine et tente d’éclairer le débat que ce phénomène suscite des deux côtés de l’Atlantique. Depuis 2010, la Chine a en effet lancé de nombreuses initiatives sur la scène internationale, en particulier en matière de commerce et d’investissements à l’étranger. Cette affirmation de la Chine incite à se poser deux questions : les gouvernements européens peuvent-ils s’accorder sur une politique commune envers la Chine ? et une plus grande coordination entre les États-Unis et l’Union européenne (UE) est-elle envisageable ? L’élaboration d’une nouvelle stratégie de politique étrangère aux États-Unis sous l’administration Trump et au sein de l’UE après les échéances électorales de 2017 présente l’opportunité d’inscrire l’harmonisation des politiques américaine et européennes envers la Chine au premier rang de leurs objectifs économiques et politiques. Cet article émet des suggestions quant à ces priorités.
Does it really rain more often on weekends than on weekdays? A case study for Slovenia
Authors: Plečko Jaka , Bezak Nejc , Škapin Rugelj Marjeta , Šraj Mojca
Published: September 2017

The article presents the results of precipitation and aerosol (PM10) data analyses in Slovenia. Analyses of rainfall data for some areas of Slovenia, such as the Ljubljana Basin, Zasavje, Šalek Valley, Celje Basin, and the coastal area, suggest that rain on the weekend is more frequent than on weekdays; nevertheless, these deviations are not statistically significant. A comparison of three separate decades showed that the pattern of weekly rainfall in the 21st century is different than that in the last period of the 20th century. The weekly cycle of PM10 for the considered stations is quite similar to that of some of the more contaminated regions of the world. Furthermore, the connection between PM10 and precipitation in most of the analyzed cases was statistically significant.
Agriculture in modern landscapes: A factor hindering or facilitating development?
Authors: Razpotnik Visković Nika , Komac Blaž
Published: September 2017

Agriculture plays an important role in both protecting and developing farmland. In Slovenia, the main reasons for this loss are urbanization and the implementation of large development projects that require the destruction of fertile farmland. About 3000 ha of farmland has been lost each year since Slovenia’s independence. The importance of agriculture and farmland is touched upon in this special issue of Acta geographica Slovenica. The authors focus on management of farmland, analyse the development potential for agriculture, observe the changes in the landscape by remote sensing, soil quality and its pollution, and land cover as an element of biodiversity. They draw attention to the lack of participation in spatial planning procedures and the question of the importance of agriculture and jobs in this sector in national economy. This introductory paper brings a short analysis of how the issue of farms’ spatial constraints and moving farm structures to new locations is perceived by municipal offices, nature parks, and the Slovenian Chamber of Agriculture and Forestry and its regional offices.
Fernando VII contra los periodistas. Los procesos seguidos por la Comisión de Causas de Estado
Authors: Sánchez Hita Beatriz
Published: September 2017

En el siguiente estudio se analizan los documentos relativos a procesos contra editores y periodistas conservados en la Comisión de Causas de Estado del Archivo Histórico Nacional (Madrid, España). A través de dichos expedientes puede dibujarse cómo se produjo la persecución de aquellos que habían tratado de crear una opinión pública favorable al régimen constitucional durante la época de las Cortes tras la reinstauración del absolutismo, qué aspectos fueron los que más ofendieron a Fernando VII y cómo los encausados articularon sus defensas para lograr ser sancionados con la menor pena posible.
Declinaciones de la reacción eclesiástica contra la Revolución francesa en España (1789-1808)
Authors: Artola Renedo Andoni , Calvo Maturana Antonio
Published: September 2017

El objetivo de este trabajo es estudiar la respuesta de la Iglesia a la amenaza planteada por la Revolución francesa. Con tal fin, se utilizarán fuentes impresas y documentos de la época que nos permitirán conocer las diferentes posturas adoptadas por el clero español, siempre desde el punto de vista de la reacción. Así, se desarrollarán cuatro epígrafes que intenten abarcar la complejidad del pensamiento eclesial a partir de 1789. El primero, se dedicará al pensamiento contrailustrado, ya existente en las décadas previas, que verá en las Luces y la revolución a un solo rival. El segundo se centrará en la tentativa de renovación de la sinergia entre el poder eclesiástico y el monárquico, producida en los textos de los eclesiásticos más cercanos al poder, generalmente más próximos también a las Luces. El tercer epígrafe pone de manifiesto cómo un sector de la Iglesia comenzó a experimentar un proceso de desafección hacia el monarca absoluto y a acercarse a posturas ultramontanas. Finalmente, el cuarto apartado se centra en el cardenal Lorenzana como ejemplo de ese proceso. La conclusión de este artículo es que el pensamiento reaccionario español fue, ya en 1789, mucho más complejo de lo que la historiografía ha percibido tradicionalmente y que ni fue absolutamente oscurantista ni totalmente afecto a la monarquía.
Constitución y verdad. La controversia entre Rafael de Vélez y Joaquín Lorenzo Villanueva a propósito de la Apología del Trono
Authors: Escrig Rosa Josep , García Monerris Encarna
Published: September 2017

El trabajo aborda el lugar del discurso antiliberal reaccionario en los primeros años de la Revolución en España. Se centra para ello en la controversia que mantuvieron el diputado liberal Joaquín Lorenzo Villanueva y el publicista y fraile capuchino Rafael de Vélez entre 1820 y 1825. Las fuentes utilizadas remiten directamente a los escritos de ambos polemistas tomando como punto de partida la «Apología del Trono» del Padre Vélez. Metodológicamente, la perspectiva de análisis adoptada parte de la consideración teórica de que la crítica al liberalismo, en sus diversas manifestaciones, fue parte inherente al proceso revolucionario y no un elemento marginal del mismo. El examen confrontado de dichas fuentes revela la complejidad histórica de la dialéctica revolución - reacción, al tiempo que trasciende el campo de la doctrina para situar a los actores en el plano de la disputa y de la acción política. Los trabajos sobre las propuestas antiliberales reaccionarias han merecido escasa atención de la historiografía. Rechazando interpretaciones sesgadas y condicionadas por viejos paradigmas historiográficos liberales o marxistas, los autores se plantean en este estudio contribuir a una comprensión integrada del proceso revolucionario entrando en la lógica interna de quiénes se opusieron a él, sus códigos de valores, las lecturas del pasado que hicieron y el futuro que proyectaron.
La faute et son ralenti. Le cadrage temporel et visuel de l’action normée
Authors: Camus Laurent
Published: September 2017

Cet article s’interroge sur le lien réflexif entre la temporalité d’une rencontre sportive et celle de sa diffusion à la télévision en direct. À partir d’une enquête vidéo-ethnographique menée en régie auprès de techniciens de l’audiovisuel qui réalisent des matches de football, cet article propose d’étudier les pratiques professionnelles par lesquelles sont traitées les pauses d’une rencontre sportive. Nous montrons comment ces pauses, pour la plupart initiées par un coup de sifflet de l’arbitre, posent un problème pratique pour la télévision. Quand le jeu est arrêté, les actions qui se déroulent ne sont plus directement orientées par la normativité propre au jeu. Or pendant ces pauses, les techniciens en régie doivent continuer à donner quelque chose à voir du match aux téléspectateurs. Grâce à une micro-analyse de l’interaction, on montre comment le coup de sifflet de l’arbitre constitue un point de transition pour l’insertion de ralentis, c’est-à-dire des séquences enregistrées donnant à revoir un phénomène de la partie sous un angle alternatif. Cela nous permet de montrer comment un élément propre au déroulement du jeu est réutilisé comme une ressource temporelle et descriptive pour l’activité de mise en images.
Rebondir après « l’échec » en centre de formation : analyse séquentielle des trajectoires socioprofessionnelles d’ex-apprentis footballeurs
Authors: Tia Pierre-Cédric
Published: September 2017

Le devenir socioprofessionnel des ex-apprentis footballeurs est un phénomène social encore insuffisamment analysé à ce jour. Les différents travaux de Frédéric Rasera (2010 ; 2014), explorant les conditions sociales individuelles de la recomposition vocationnelle chez un ex-apprenti footballeur, font office d’exception. Face à ce constat, cet article entend contribuer à la réflexion portant sur ces jeunes sportifs. À travers l’étude des trajectoires d’une vingtaine d’ex-apprentis footballeurs, nous verrons qu’il est possible de trouver des similarités biographiques caractérisant leur processus de recomposition vocationnelle. Plus précisément, nous montrerons qu’une analyse en termes de temporalités vécues (Dubar, 2014) permet de dévoiler la résurgence de quatre séquences de vie (choc, persévérance, dilemme et metanoïa) au cours de leur recomposition vocationnelle, révélant ainsi, les dimensions collectives de ce processus.
Socialisations temporelles dans le sport de haut niveau
Authors: Julla-Marcy Mathilde , Burlot Fabrice , Mancq Fanny Le
Published: September 2017

À travers une enquête qualitative par entretiens menée auprès des sportifs de haut niveau de l’INSEP, nous nous intéressons à leur rythme de vie qui articule des temps nombreux et variés : temps sportif (entraînement, préparation, compétition), temps scolaire ou universitaire, temps professionnel, temps de récupération, temps de loisir privé et social, etc. Dans ce contexte il apparaît que leur temps objectif (l’organisation de leur emploi du temps) et leur temps subjectif (le vécu de celui-ci) ne coïncident pas toujours. Nous identifions à la fois une capacité générale de ces sportifs à gérer une organisation temporelle particulièrement chargée (dont ils sont souvent demandeurs), mais aussi de profondes variations d’un profil de sportif à l’autre, d’où l’idée d’une construction sociale du temps subjectif. Après avoir présenté l’organisation objective des temps à l’INSEP, nous analysons le poids de plusieurs facteurs sportifs et extra-sportifs pour expliquer cette disjonction et comprendre quels éléments ont tendance à favoriser un meilleur vécu d’un emploi du temps objectivement chargé. Cela nous conduit à ouvrir la discussion sur la conception des différentes temporalités de la préparation des sportifs qui demeure floue, entre temps de travail et temps de loisir. Cette préparation s’inscrit elle-même dans un contexte institutionnel spécifique : la construction du rythme de vie de ces sportifs est alors la recherche d’un compromis entre temps collectif (et contraignant) et temps individuel (et maîtrisé).