bluuebunny/crossref_metadata_2025_split huggingface dataset:
The NuSTAR Extragalactic Surveys: X-Ray Spectroscopic Analysis of the Bright Hard-band Selected Sample
Authors: Zappacosta L. , Comastri A. , Civano F. , Puccetti S. , Fiore F. , Aird J. , Moro A. Del , Lansbury G. B. , Lanzuisi G. , Goulding A. , Mullaney J. R. , Stern D. , Ajello M. , Alexander D. M. , Ballantyne D. R. , Bauer F. E. , Brandt W. N. , Chen C.-T. J. , Farrah D. , Harrison F. A. , Gandhi P. , Lanz L. , Masini A. , Marchesi S. , Ricci C. , Treister E. 
Published: February 2018

Abstract
We discuss the spectral analysis of a sample of 63 active galactic nuclei (AGN) detected above a limiting flux of

in the multi-tiered NuSTAR extragalactic survey program. The sources span a redshift range

(median

). The spectral analysis is performed over the broad 0.5–24 keV energy range, combining NuSTAR with Chandra and/or XMM-Newton data and employing empirical and physically motivated models. This constitutes the largest sample of AGN selected at

to be homogeneously spectrally analyzed at these flux levels. We study the distribution of spectral parameters such as photon index, column density (

), reflection parameter (

), and 10–40 keV luminosity (

). Heavily obscured (

) and Compton-thick (CT;

) AGN constitute ∼25% (15–17 sources) and ∼2–3% (1–2 sources) of the sample, respectively. The observed

distribution agrees fairly well with predictions of cosmic X-ray background population-synthesis models (CXBPSM). We estimate the intrinsic fraction of AGN as a function of

, accounting for the bias against obscured AGN in a flux-selected sample. The fraction of CT AGN relative to

AGN is poorly constrained, formally in the range 2–56% (90% upper limit of 66%). We derived a fraction (f
abs) of obscured AGN (

) as a function of

in agreement with CXBPSM and previous

X-ray determinations. Furthermore, f
abs at

and

agrees with observational measurements/trends obtained over larger redshift intervals. We report a significant anti-correlation of R with

(confirmed by our companion paper on stacked spectra) with considerable scatter around the median R values.
The JCMT Transient Survey: Stochastic and Secular Variability of Protostars and Disks In the Submillimeter Region Observed over 18 Months
Authors: Johnstone Doug , Herczeg Gregory J. , Mairs Steve , Hatchell Jennifer , Bower Geoffrey C. , Kirk Helen , Lane James , Bell Graham S. , Graves Sarah , Aikawa Yuri , Chen Huei-Ru Vivien , Chen Wen-Ping , Kang Miju , Kang Sung-Ju , Lee Jeong-Eun , Morata Oscar , Pon Andy , Scicluna Peter , Scholz Aleks , Takahashi Satoko , Yoo Hyunju ,   The JCMT Transient Team
Published: February 2018

Abstract
We analyze results from the first 18 months of monthly submillimeter monitoring of eight star-forming regions in the JCMT Transient Survey. In our search for stochastic variability in 1643 bright peaks, only the previously identified source, EC 53, shows behavior well above the expected measurement uncertainty. Another four sources—two disks and two protostars—show moderately enhanced standard deviations in brightness, as expected for stochastic variables. For the two protostars, this apparent variability is the result of single epochs that are much brighter than the mean. In our search for secular brightness variations that are linear in time, we measure the fractional brightness change per year for 150 bright peaks, 50 of which are protostellar. The ensemble distribution of slopes is well fit by a normal distribution with σ ∼ 0.023. Most sources are not rapidly brightening or fading at submillimeter wavelengths. Comparison against time-randomized realizations shows that the width of the distribution is dominated by the uncertainty in the individual brightness measurements of the sources. A toy model for secular variability reveals that an underlying Gaussian distribution of linear fractional brightness change σ = 0.005 would be unobservable in the present sample, whereas an underlying distribution with σ = 0.02 is ruled out. Five protostellar sources, 10% of the protostellar sample, are found to have robust secular measures deviating from a constant flux. The sensitivity to secular brightness variations will improve significantly with a sample over a longer time duration, with an improvement by factor of two expected by the conclusion of our 36 month survey.
Laboratory Gas-phase Infrared Spectra of Two Astronomically Relevant PAH Cations: Diindenoperylene,
and Dicoronylene,
Authors: Zhen Junfeng , Candian Alessandra , Castellanos Pablo , Bouwman Jordy , Linnartz Harold , Tielens Alexander G. G. M. 
Published: February 2018

Abstract
The first gas-phase infrared spectra of two isolated astronomically relevant and large polycyclic aromatic hydrocarbon (PAH) cations—diindenoperylene (DIP) and dicoronylene (DC)—in the 530–1800 cm−1 (18.9−5.6 μm) range—are presented. Vibrational band positions are determined for comparison to the aromatic infrared bands. The spectra are obtained via infrared multiphoton dissociation spectroscopy of ions stored in a quadrupole ion trap using the intense and tunable radiation of the free electron laser for infrared experiments (FELIX). DIP+ shows its main absorption peaks at 737 (13.57), 800 (12.50), 1001 (9.99), 1070 (9.35), 1115 (8.97), 1152 (8.68), 1278 (7.83), 1420 (7.04), and 1550 (6.45) cm−1(μm), in good agreement with density functional theory (DFT) calculations that are uniformly scaled to take anharmonicities into account. DC+ has its main absorption peaks at 853 (11.72), 876 (11.42), 1032 (9.69), 1168 (8.56), 1300 (7.69), 1427 (7.01), and 1566 (6.39) cm−1(μm), which also agree well with the scaled DFT results presented here. The DIP+ and DC+ spectra are compared with the prominent infrared features observed toward NGC 7023. This results both in matches and clear deviations. Moreover, in the 11.0–14.0 μm region, specific bands can be linked to CH out-of-plane (oop) bending modes of different CH edge structures in large PAHs. The molecular origin of these findings and their astronomical relevance are discussed.
Observations of Electron-driven Evaporation in a Flare Precursor
Authors: Li Dong , Li Ying , Su Wei , Huang Yu , Ning Zongjun 
Published: February 2018

Abstract
We investigate the relationship between the blueshifts of a hot emission line and the nonthermal emissions in microwave and hard X-ray (HXR) wavelengths in the precursor of a solar flare on 2014 October 27. The flare precursor is identified as a small but well-developed peak in the soft X-ray and extreme-ultraviolet passbands before the GOES flare onset, which is accompanied by a pronounced burst in microwave 17 and 34 GHz and in HXR 25–50 keV. The slit of the Interface Region Imaging Spectrograph (IRIS) stays on one ribbon-like transient during the flare precursor phase, which shows visible nonthermal emissions in Nobeyama Radioheliograph and RHESSI images. The IRIS spectroscopic observations show that the hot line of Fe xxi 1354.09 Å (log T ∼ 7.05) displays blueshifts, while the cool line of Si iv 1402.77 Å (log T ∼ 4.8) exhibits redshifts. The blueshifts and redshifts are well correlated with each other, indicative of an explosive chromospheric evaporation during the flare precursor phase combining a high nonthermal energy flux with a short characteristic timescale. In addition, the blueshifts of Fe xxi 1354.09 Å are well correlated with the microwave and HXR emissions, implying that the explosive chromospheric evaporation during the flare precursor phase is driven by nonthermal electrons.
Spitzer Observations of the North Ecliptic Pole
Authors: Nayyeri H. , Ghotbi N. , Cooray A. , Bock J. , Clements D. L. , Im M. , Kim M. G. , Korngut P. , Lanz A. , Lee H. M. , Lee D. H. , Malkan M. , Matsuhara H. , Matsumoto T. , Matsuura S. , Nam U. W. , Pearson C. , Serjeant S. , Smidt J. , Tsumura K. , Wada T. , Zemcov M. 
Published: February 2018

Abstract
We present a photometric catalog for Spitzer Space Telescope warm mission observations of the North Ecliptic Pole (NEP; centered at R.A. = 18h00m00s, decl. = 66d33m38.ˢ552). The observations are conducted with IRAC in the 3.6 and 4.5 μm bands over an area of 7.04 deg2, reaching 1σ depths of 1.29 μJy and 0.79 μJy in the 3.6 μm and 4.5 μm bands, respectively. The photometric catalog contains 380,858 sources with 3.6 and 4.5 μm band photometry over the full-depth NEP mosaic. Point-source completeness simulations show that the catalog is 80% complete down to 19.7 AB. The accompanying catalog can be used for constraining the physical properties of extragalactic objects, studying the AGN population, measuring the infrared colors of stellar objects, and studying the extragalactic infrared background light.
Benchmarking Atomic Data for Astrophysics: Be-like Ions between B ii and Ne vii
Authors: Wang Kai , Chen Zhan Bin , Zhang Chun Yu , Si Ran , Jönsson Per , Hartman Henrik , Gu Ming Feng , Chen Chong Yang , Yan Jun 
Published: February 2018

Abstract
Large-scale self-consistent multiconfiguration Dirac–Hartree–Fock and relativistic configuration interaction calculations are reported for the

levels in Be-like ions from B ii to Ne vii. Effects from electron correlation are taken into account by means of large expansions in terms of a basis of configuration state functions, and a complete and accurate data set of excitation energies; lifetimes; wavelengths; electric dipole, magnetic dipole, electric quadrupole, and magnetic quadrupole line strengths; transition rates; and oscillator strengths for these levels is provided for each ion. Comparisons are made with available experimental and theoretical results. The uncertainty of excitation energies is assessed to be 0.01% on average, which makes it possible to find and rule out misidentifications and aid new line identifications involving high-lying levels in astrophysical spectra. The complete data set is also useful for modeling and diagnosing astrophysical plasmas.
La croyance à l’épreuve du groupe
Authors: Gozlan Angélique , Potier Rémy 
Published: February 2018

Cet article rend compte de l’enjeu groupal dans une prise en charge multifocale d’un adolescent au sein de l’association O.S.E (Œuvre de Secours aux Enfants). Nous interrogeons la notion de la croyance au regard d’un groupe thérapeutique de parole pour adolescents. La question de la croyance est pensée dans l’une de ses dimensions comme entrave aux processus de soin, échec lié à un mécanisme de défense face à l’étranger. Comment la croyance pour un adolescent s’avère-t-elle être un mécanisme de défense ? S’agit-il ici de croyance ou de crédulité ? Le développement et l’analyse du cas de Yigdal mettront en relief les alliances et résonnances inconscientes autour de la croyance dans ce groupe. Ils permettront de saisir la transformation d’une croyance groupale en une crédulité toute individuelle qui s’aménagera comme défense à l’altérité et au processus de subjectivation adolescent.
“The Prince and the Magic Magnet”: An Ethnographic Tale of Technology, Power and Health in Africa
Authors: Werner Jean-François 
Published: February 2018

Sous la forme d’un conte ethnographique, l’auteur décrit dans quelles circonstances, au début du XXIe siècle, un équipement d’imagerie par résonance magnétique (IRM) fut installé et mis en service dans un petit pays d’Afrique de l’Ouest de par la volonté du Prince qui le gouvernait. Il montre ensuite qu’en agissant ainsi ce dernier reprenait à son compte la croyance selon laquelle l’imagerie médicale, en rendant le corps transparent, améliorait la qualité des soins et permettait de faire des économies. Deux assertions qui n’ont pas été confirmées, comme le montre la suite de l’histoire. En cause, le coût trop élevé des examens qui limitait l’accès à cette technologie à la minorité de la population (15 %) pourvue d’une assurance maladie. Avec pour conséquence le fait que, au lieu d’améliorer le fonctionnement du système de santé, l’introduction de cette technologie n’a fait que renforcer les inégalités d’accès aux soins et souligner les insuffisances et faiblesses de l’appareil de soins. En conclusion, l’auteur attire l’attention sur la difficulté d’échapper à l’attraction du mythe de la technologie en tant que facteur indispensable au développement social et économique, tant celui-ci est enraciné dans une construction socio-historique établie de longue date et désormais mondialisée.
Improved optical flow velocity analysis in SO2 camera images of volcanic plumes – implications for emission-rate retrievals investigated at Mt Etna, Italy and Guallatiri, Chile
Authors: Gliß Jonas , Stebel Kerstin , Kylling Arve , Sudbø Aasmund 
Published: February 2018

Abstract. Accurate gas velocity measurements in emission plumes are highly desirable for various atmospheric remote sensing applications. The imaging technique of UV SO2 cameras is commonly used to monitor SO2 emissions from volcanoes and anthropogenic sources (e.g. power plants, ships). The camera systems capture the emission plumes at high spatial and temporal resolution. This allows the gas velocities in the plume to be retrieved directly from the images. The latter can be measured at a pixel level using optical flow (OF) algorithms. This is particularly advantageous under turbulent plume conditions. However, OF algorithms intrinsically rely on contrast in the images and often fail to detect motion in low-contrast image areas. We present a new method to identify ill-constrained OF motion vectors and replace them using the local average velocity vector. The latter is derived based on histograms of the retrieved OF motion fields. The new method is applied to two example data sets recorded at Mt Etna (Italy) and Guallatiri (Chile). We show that in many cases, the uncorrected OF yields significantly underestimated SO2 emission rates. We further show that our proposed correction can account for this and that it significantly improves the reliability of optical-flow-based gas velocity retrievals. In the case of Mt Etna, the SO2 emissions of the north-eastern crater are investigated. The corrected SO2 emission rates range between 4.8 and 10.7 kg s−1 (average of 7.1  ±  1.3 kg s−1) and are in good agreement with previously reported values. For the Guallatiri data, the emissions of the central crater and a fumarolic field are investigated. The retrieved SO2 emission rates are between 0.5 and 2.9 kg s−1 (average of 1.3  ±  0.5 kg s−1) and provide the first report of SO2 emissions from this remotely located and inaccessible volcano.
Effects of storage temperature on the physiological characteristics and vegetative propagation of desiccation-tolerant mosses
Authors: Guo Yuewei , Zhao Yunge 
Published: February 2018

Abstract. Mosses, as major components of later successional biological soil crusts (biocrusts), play many critical roles in arid and semiarid ecosystems. Recently, some species of desiccation-tolerant mosses have been artificially cultured with the aim of accelerating the recovery of biocrusts. Revealing the factors that influence the vegetative propagation of mosses, which is an important reproductive mode of mosses in dry habitats, will benefit the restoration of moss crusts. In this study, three air-dried desiccation-tolerant mosses (Barbula unguiculata, Didymodon vinealis, and Didymodon tectorum) were hermetically sealed and stored at five temperature levels (0, 4, 17, 25, and 30 °C) for 40 days. Then, the vegetative propagation and physiological characteristics of the three mosses were investigated to determine the influence of storage temperature on the vegetative propagation of desiccation-tolerant mosses and the mechanism. The results showed that the vegetative propagation of the three mosses varied with temperature. The most variation in vegetative propagation among storage temperatures was observed in D. tectorum, followed by the variation observed in B. unguiculata. In contrast, no significant difference in propagation among temperatures was found in D. vinealis. The regenerative capacity of the three mosses increased with increasing temperature from 0 to 17 °C, accompanied by a decrease in malondialdehyde (MDA) content, and decreased thereafter. As the temperature increased, the chlorophyll and soluble protein contents increased in B. unguiculata but decreased in D. vinealis and D. tectorum. As to storage, the MDA and soluble sugar contents increased after storage. The MDA content of the three mosses increased at each of the investigated temperatures by more than 50 % from the initial values, and the soluble sugar content became higher than before in the three mosses. The integrity of cells and cell membranes is likely the most important factor influencing the vegetative propagation of desiccation-tolerant mosses. A 40-day storage period caused cell injury. Our results suggest that storage temperature can enhance or suppress such injury and change the regenerative capacity of the three mosses. The data indicate that the suitable storage temperature is 4 °C for B. unguiculata and 17 °C for both D. vinealis and D. tectorum.
Human influences on streamflow drought characteristics in England and Wales
Authors: Tijdeman Erik , Hannaford Jamie , Stahl Kerstin 
Published: February 2018

Abstract. Human influences can affect streamflow drought characteristics and
propagation. The question is where, when and why? To answer these questions,
the impact of different human influences on streamflow droughts were assessed
in England and Wales, across a broad range of climate and catchments
conditions. We used a dataset consisting of catchments with near-natural flow
as well as catchments for which different human influences have been
indicated in the metadata (“Factors Affecting Runoff”) of the UK National
River Flow Archive (NRFA). A screening approach was applied on the streamflow
records to identify human-influenced records with drought characteristics
that deviated from those found for catchments with near-natural flow. Three
different deviations were considered, specifically deviations in (1) the
relationship between streamflow drought duration and the base flow index, BFI
(specifically, BFIHOST, the BFI predicted from the hydrological properties of
soils), (2) the correlation between streamflow and precipitation and (3) the
temporal occurrence of streamflow droughts compared to precipitation
droughts, i.e. an increase or decrease in streamflow drought months relative
to precipitation drought months over the period of record. The identified
deviations were then related to the indicated human influences. Results
showed that the majority of catchments for which human influences were
indicated did not show streamflow drought characteristics that deviated from
those expected under near-natural conditions. For the catchments that did
show deviating streamflow drought characteristics, prolonged streamflow
drought durations were found in some of the catchments affected by
groundwater abstractions. Weaker correlations between streamflow and
precipitation were found for some of the catchments with reservoirs, water
transfers or groundwater augmentation schemes. An increase in streamflow
drought occurrence towards the end of their records was found for some of the
catchments affected by groundwater abstractions and a decrease in streamflow
drought occurrence for some of the catchments with either reservoirs or
groundwater abstractions. In conclusion, the proposed screening approaches
were sometimes successful in identifying streamflow records with deviating
drought characteristics that are likely related to different human
influences. However, a quantitative attribution of the impact of human
influences on streamflow drought characteristics requires more detailed
case-by-case information about the type and degree of all different human
influences. Given that, in many countries, such information is often not
readily accessible, the approaches adopted here could provide useful in
targeting future efforts. In England and Wales specifically, the catchments
with deviating streamflow drought characteristics identified in this study
could serve as the starting point of detailed case study research.
On a grain of sand – a microhabitat for the opportunistic agglutinated foraminifera &lt;i&gt;Hemisphaerammina apta&lt;/i&gt; n. sp., from the early Eocene Arctic Ocean
Authors: McNeil David H. , Neville Lisa A. 
Published: February 2018

Abstract. Hemisphaerammina apta n. sp. is an attached monothalamous agglutinated foraminifera discovered in shelf sediments of the early Eocene Arctic Ocean. It is a simple yet distinctive component of the endemic agglutinated foraminiferal assemblage that colonized the Arctic Ocean after the microfaunal turnover caused by the Paleocene–Eocene Thermal Maximum. Associated foraminifera are characterized by a high percentage of monothalamous species (up to 60 %) and are entirely agglutinated indicating a brackish (mesohaline) early Eocene Arctic Ocean. Hemisphaerammina apta occurs exclusively as individuals attached to fine detrital grains (0.2 to 1.8 mm) of sediment. It is a small species (0.06 to 0.2 mm in diameter), fine-grained, with a low hemispherical profile, no floor across the attachment area, no substantive marginal flange, no internal structures, and no aperture. Lacking an aperture, it apparently propagated and fed through minute (micrometre-sized) interstitial pores in the test wall. Attachment surfaces vary from concave to convex and rough to smooth. Grains for attachment are diverse in shape and type but are predominantly of quartz and chert. The presence of H. apta in the early Eocene was an opportunistic response to an environment with an active hydrological system (storm events). Attachment to grains of sand would provide a more stable base on a sea floor winnowed by storm-generated currents. Active transport is indicated by the relative abundance of reworked foraminifera mixed with in situ species. Contemporaneous reworking and colonization by H. apta is suggested by its attachment to a reworked specimen of Cretaceous foraminifera.