bluuebunny/crossref_metadata_2025 huggingface dataset:
A Molecular CO2 Reduction Catalyst Based on Giant Polyoxometalate {Mo368}
Authors: Das Santu , Balaraju Tuniki , Barman Soumitra , Sreejith S. S. , Pochamoni Ramudu , Roy Soumyajit
Published: November 2018

Photocatalytic CO2 reduction in water is one of the most attractive research pursuits of our time. In this article we report a giant polyoxometalate {Mo368} based homogeneous catalytic system, which efficiently reduces CO2 to formic acid with a maximum turnover number (TON) of 27,666, turnover frequency (TOF) of 4,611 h−1 and external quantum efficiency of the reaction is 0.6%. The catalytic system oxidizes water and releases electrons, and these electrons are further utilized for the reduction of CO2 to formic acid. A maximum of 8.3 mmol of formic acid was observed with the loading of 0.3 μmol of the catalyst. Our catalyst material is also stable throughout the reaction. The starting materials for this experiment are CO2 and H2O and the end products are HCOOH and O2. The formic acid formed in this reaction is an important H2 gas carrier and thus significant in renewable energy research.
Characterization of Mesoscale Waves in the Jupiter NEB by Jupiter InfraRed Auroral Mapper on board Juno
Authors: Adriani A. , Moriconi M. L. , Altieri F. , Sindoni G. , Ingersoll A. P. , Grassi D. , Mura A. , Atreya S. K. , Orton G. , Lunine J. I. , Fletcher L. N. , Simon A. A. , Melin H. , Tosi F. , Cicchetti A. , Noschese R. , Sordini R. , Levin S. , Bolton J. , Plainaki C. , Olivieri A.
Published: November 2018

In 2017, the Jupiter InfraRed Auroral Mapper (JIRAM), on board the NASA-ASI Juno mission, observed a wide longitude region (50° W–80° E in System III) that was perturbed by a wave pattern centered at 15° N in the Jupiter’s North Equatorial Belt (NEB). We analyzed JIRAM data acquired on 2017 July 10 using the M-channel and on 2017 February 2 with the spectrometer. The two observations occurred at different times and at slightly different latitudes. The waves appear as clouds blocking the deeper thermal emission. The wave crests are oriented north–south, and the typical wave packet contains 10 crests and 10 troughs. We used Fourier analysis to rigorously determine the wavenumbers associated with the observed patterns at a confidence level of 90%. Wavelet analysis was also used to constrain the spatial localization of the largest energies involved in the process and determine the wavelengths carrying the major contribution. We found wavelengths ranging from 1400 to 1900 km, and generally decreasing toward the west. Where possible, we also computed a vertical location of the cloud pressure levels from the inversion of the spectral radiances measured by the JIRAM spectrometer. The waves were detected at pressure levels consistent with the NH3 as well as NH4SH clouds. Phase velocities could not be determined with sufficient confidence to discriminate whether the alternating crests and troughs are a propagating wave or a manifestation of a fluid dynamical instability.
Radial Velocity and Chemical Composition of Evolved Stars in the Open Clusters NGC 6940 and Tombaugh 5
Authors: Baratella Martina , Carraro Giovanni , D’Orazi Valentina , Semenko Eugene A.
Published: November 2018

We present and discuss medium resolution (R ∼ 13000), high signal-to-noise (

), spectroscopic observations in the field of the open clusters NGC 6940 and Tombaugh 5. Spectra were recorded for seven candidate red giant stars in both clusters. For the latter, we present the very first chemical abundance analysis. We derive radial velocities for all the stars in NGC 6940, confirming membership to the cluster for all of them, while on the same ground, we exclude two stars in To 5. We perform a chemical abundance analysis of different atomic species, in particular Fe i, Si i, Ca i, Ti i, and Ni i. The mean metallicity of NGC 6940 is [Fe/H] = +0.09 ± 0.06 dex, in good agreement with previous works, while for To 5 is [Fe/H] = +0.06 ± 0.11 dex. Therefore, both clusters exhibit a chemical composition close to the solar value and do not deviate from the [Fe/H] Galactic radial abundance gradient. With these new values, we estimate the fundamental cluster parameters, after having derived clusters’ distances from the Gaia DR2 database. By adopting these distances, we derive updated estimated for the clusters ages: 1.0 ± 0.1 Gyr of NGC 6940 and 0.25 ± 0.05 Gyr for Tombaugh 5.
Probing Oort Clouds around Milky Way Stars with CMB Surveys
Authors: Baxter Eric J. , Blake Cullen H. , Jain Bhuvnesh
Published: November 2018

Long-period comets observed in our solar system are believed to originate from the Oort cloud, which is estimated to extend from roughly a few thousand to 105 au from the Sun. Despite many theoretical arguments for the existence of the Oort cloud, no direct observations of outer Oort cloud objects have been reported. Here, we explore the possibility of measuring Oort clouds around other stars through their emission at submillimeter wavelengths. Observations with the 545 and 857 GHz bands of the Planck satellite are well matched to the expected temperatures of Oort cloud bodies (on the order of 10 K). By correlating the Planck maps with catalogs of stars observed by the Gaia mission, we are able to constrain interesting regions of the exo-Oort cloud (EXOC) parameter space, placing limits on the total mass and the minimum size of grains in the cloud. We compare our measurements with known debris disk systems—in the case of Vega and Fomalhaut, we find a significant excess that is in agreement with measurements from Herschel. We use the measurements around Fomalhaut to constrain a possible EXOC of that system. We explore an observed excess around the brightest and nearest stars in our sample as arising from possible EXOCs or other extended sources of thermal emission. We argue that future CMB surveys and targeted observations with far-infrared and millimeter wavelength telescopes have the potential to detect EXOCs or other extended sources of thermal emission beyond ∼1000 au from the parent stars.
Kinematic Identification of Young Nearby Moving Groups from a Sample of Chromospherically Active Stars in the RAVE Catalog
Authors: Ramírez-Preciado Valeria G. , Román-Zúñiga Carlos G. , Aguilar Luis , Suárez Genaro , Downes Juan José
Published: November 2018

The purpose of this study is the identification of young (1 < age < 100 Myr), nearby (d ≤ 100 pc) moving groups (YNMGs) through their kinematic signature. YNMGs could be the result of the recent dispersal of young embedded clusters, such that they still represent kinematically cold groups, carrying the residual motion of their parental cloud. Using the fact that a large number (∼14,000) of the RAVE sources with evidence of chromospheric activity also present signatures of stellar youth, we selected a sample of solar-type sources with the highest probability of chromospheric activity to look for common kinematics. We made use of radial velocity information from RAVE and astrometric parameters from GAIA DR2 to construct a 6D position–velocity vector catalog for our full sample. We developed a method based on the grouping of stars with similar orientation of their velocity vectors, which we call the Cone Method Sampling. Using this method, we detected 646 sources with high significance in the velocity space, with respect to the average orientation of artificial distributions made from a purely Gaussian velocity ellipsoid with null vertex deviation. We compared this sample of highly significant sources with a catalog of YNMGs reported in previous studies, which yield 75 confirmed members. From the remaining sample, about 50% of the sources have ages younger than 100 Myr, which indicate they are highly probable candidates to be new members of identified or even other YNMGs in the solar neighborhood.
The Widespread Presence of Nanometer-size Dust Grains in the Interstellar Medium of Galaxies
Authors: Xie Yanxia , Ho Luis C. , Li Aigen , Shangguan Jinyi
Published: November 2018

Interstellar dust spans a wide range in size distribution, ranging from ultrasmall grains of a few Ångströms to micrometer-size grains. While the presence of nanometer-size dust grains in the Galactic interstellar medium was speculated six decades ago and was previously suggested based on early infrared observations, systematic and direct analysis of their properties over a wide range of environments has been lacking. Here we report the detection of nanometer-size dust grains that appear to be universally present in a wide variety of astronomical environments, from Galactic high-latitude clouds to nearby star-forming galaxies and galaxies with low levels of nuclear activity. The prevalence of such a grain population is revealed conclusively as prominent mid-infrared continuum emission at λ ≲ 10 μm seen in the Spitzer/Infrared Spectrograph data, characterized by temperatures of ∼300–400 K that are significantly higher than the equilibrium temperatures of common, submicron-size grains in typical galactic environments. We propose that the optimal carriers of this pervasive, featureless hot dust component are very small carbonaceous (e.g., graphite) grains of nanometer size that are transiently heated by single-photon absorption. This grain population accounts for ∼1.4% of the total infrared emission at ∼5–3000 μm and ∼0.4% of the total interstellar dust mass.
A Systematic Study of Hale and Anti-Hale Sunspot Physical Parameters
Authors: Li Jing
Published: November 2018

We present a systematic study of sunspot physical parameters using full-disk magnetograms from the Michelson Doppler Imager/Solar and Heliospheric Observatory and the Helioseismic and Magnetic Imager/Solar Dynamic Observatory. Our aim is to use uniform data sets and analysis procedures to characterize the sunspots, paying particular attention to the differences and similarities between “Hale” and “anti-Hale” spots. Included are measurements of the magnetic tilt angles, areas, fluxes, and polarity pole separations for 4385 sunspot groups in Cycles 23 and 24 each measured, on average, at ∼66 epochs centered on meridian crossing. The sunspots are classified as either “Hale” or “anti-Hale,” depending on whether their polarities align or anti-align with Hale’s hemispheric polarity rule. We find that (1) the “anti-Hale” sunspots constitute a fraction (8.1 ± 0.4)% of all sunspots, and this fraction is the same in both hemispheres and cycles; (2) “Hale” sunspots obey Joy’s law in both hemispheres and cycles but “anti-Hale” sunspots do not—three equivalent forms of Joy’s law are derived:

γ = (0.39 ± 0.06) ϕ, and

, where γ is the tilt angle and ϕ is the heliospheric latitude; (3) the average Hale sunspot tilt angle is

and (4) the tilt angles, magnetic fluxes, and pole separations of sunspots are interrelated, with larger fluxes correlated with larger pole separations and smaller tilt angles. We present empirical relations between these quantities. Cycle 24 is a much weaker cycle than Cycle 23 in sunspot numbers, cumulative magnetic flux, and average sunspot magnetic flux. The “anti-Hale” sunspots are also much weaker than “Hale” sunspots in those parameters, but they share similar magnetic flux distributions and average latitudes. We characterize the two populations, and aim to shed light on the origin of “anti-Hale” sunspots.
Data on Inelastic Processes in Low-energy Calcium–Hydrogen Ionic Collisions
Authors: Belyaev Andrey K. , Voronov Yaroslav V. , Gadéa Florent Xavier
Published: November 2018

The nonadiabatic nuclear dynamics for the 17 low-lying molecular states of the

collisional system is studied by the probabilistic version of the hopping probability current method based on the accurate ab initio adiabatic potentials. Inelastic Ca+ + H, Ca + H+, and Ca2+ + H− collisions are treated, and partial cross sections and rate coefficients for all transitions between the considered scattering channels are calculated for excitation, de-excitation, charge exchange, ion-pair formation, and neutralization processes. The cross sections and the rate coefficients for the 272 partial inelastic processes are computed. It is found that the reaction mechanism for the partial processes with high-valued rates is due to the long-range ionic–covalent interaction, while for some processes with moderate-valued rates it is due to short-range nonadiabatic regions. It is shown that the largest rate coefficients correspond to the neutralization and also charge exchange processes from the optimal window. The largest rate coefficient exceeds the value

. It is also found that some two-electron-transition charge exchange processes have rate coefficients as large as one-electron-transition processes. The processes with large and moderate values of rate coefficients are likely to be important for stellar spectra modeling.
AstroSat and Chandra View of the High Soft State of 4U 1630–47 (4U 1630–472): Evidence of the Disk Wind and a Rapidly Spinning Black Hole
Authors: Pahari Mayukh , Bhattacharyya Sudip , Rao A R , Bhattacharya Dipankar , Vadawale Santosh V , Dewangan Gulab C , McHardy I M , Gandhi Poshak , Corbel Stéphane , Schulz Norbert S , Altamirano Diego
Published: November 2018

We present the X-ray spectral and timing analysis of the transient black hole X-ray binary 4U 1630–47, observed with the AstroSat, Chandra, and MAXI space missions during its soft X-ray outburst in 2016. The outburst, from the rising phase until the peak, is detected neither in hard X-rays (15–50 keV) by the Swift/BAT nor in radio. Such nondetection, along with the source behavior in the hardness–intensity and color–color diagrams obtained using MAXI data, confirms that both Chandra and AstroSat observations were performed during the HS spectral state. The High Energy Grating (HEG) spectrum from the Chandra High-Energy Transmission Grating Spectrometer shows two strong, moderately blueshifted absorption lines at

keV and

keV, which are produced by Fe xxv and Fe xxvi in a low-velocity ionized disk wind. The corresponding outflow velocity is determined to be 366 ± 56 km s−1. Separate spectral fits of Chandra/HEG, AstroSat/SXT+LAXPC, and Chandra/HEG+AstroSat/SXT+LAXPC data show that the broadband continuum can be well described with a relativistic disk blackbody model, with a disk flux fraction of ∼0.97. Based on the best-fit continuum spectral modeling of Chandra, AstroSat, and Chandra+AstroSat joint spectra and using the Markov chain Monte Carlo simulations, we constrain the spectral hardening factor at

and the dimensionless black hole spin parameter at 0.92 ± 0.04 within the 99.7% confidence interval. Our conclusion of a rapidly spinning black hole in 4U 1630–47 using the continuum spectrum method is in agreement with a previous finding applying the reflection spectral fitting method.
Conducting Replication Studies With Confidence
Authors: Morin Karen H.
Published: November 2018

Although essential to the development of a robust evidence base for nurse educators, the concepts of replication and reproducibility have received little attention in the nursing education literature. In this Methodology Corner installment, the concepts of study replication and reproducibility are explored in depth. In designing, conducting, and documenting the findings of studies in nursing education, researchers are encouraged to make design choices that improve study replicability and reproducibility of study findings. [
J Nurs Educ.
2018;57(11):638–640.]
Perceived Effectiveness of an English-as-an-Additional-Language Nursing Student Support Program
Authors: Choi Liza Lai Shan
Published: November 2018

Background:

English-as-an-Additional-Language (EAL) nursing students are more likely to experience academic challenges than nursing students whose primary language is English. To improve the learning environment for this disadvantaged group of students, a novel support group was established to address both academic and nonacademic issues faced by these students.

Method:

Using a hermeneutic analytic approach, the impact and perceived effectiveness of this support group are explored.

Results:

The deliberate design of this support group provided significant support for EAL nursing students in both the academic and non-academic realms.

Conclusion:

Participants perceived the formation of a holistic, curriculum-specific tailored support group as an effective tool for educating EAL nursing students. [
J Nurs Educ
. 2018;57(11):641–647.]
Virtual Interprofessional Learning
Authors: Fowler Terri , Phillips Shannon , Patel Sachin , Ruggiero Ken , Ragucci Kelly , Kern Donna , Stuart Gail
Published: November 2018

Background:

Interprofessional education is a challenge given the current constraints of clinical education, which is bound by space, location, off-campus clinical rotations, and conflicting academic schedules. New approaches need to be developed if academic settings are to provide high-impact interprofessional education.

Method:

Virtual Interprofessional (VIP) Learning was developed as an innovative, online, asynchronous learning platform utilizing avatars that engages learners in interprofessional clinical learning opportunities across disciplines and settings. Teams of interprofessional students worked together to complete a real-life case scenario focused on patient quality and safety using root cause analysis and interprofessional communication.

Results:

Evaluation via focus groups, self-assessment survey, and a platform usability assessment found an increase in students' interprofessional knowledge, attitudes, and preference for virtual interprofessional experiences.

Conclusion:

VIP Learning is an innovative approach to advance interprofessional education from siloed, limited experiences to accessible and interactive opportunities that are not bound by time or place. [
J Nurs Educ
. 2018;57(11):668–674.]
Identifying Motivational Factors for Enrolling in a Doctor of Nursing Practice Program
Authors: Robb Meigan , Hunker Diane F.
Published: November 2018

Background:

Students enter Doctor of Nursing Practice (DNP) programs for varying reasons. An understanding of motivational factors is needed so nurse educators can address upon program entry student engagement strategies to promote retention and success in completing a DNP program. This article presents the findings of a descriptive study that explored newly admitted students' motivational factors for pursing DNP education.

Method:

A 20-item online survey was distributed to newly admitted DNP students at a university in western Pennsylvania. The survey consisted of eight demographic questions and 12 statements that reflected six intrinsic and six extrinsic motivational factors.

Results:

Intrinsic motivational factors were reported as slightly more influential than extrinsic motivational factors. Relationships were found between length of employment, length of experience, length of time considering to enroll, and motivational factors.

Conclusion:

Cultivating intrinsic motivation upon program entry may positively influence engagement, retention, and successful program completion of DNP students'. [
J Nurs Educ
. 2018;57(11):680–683.]
Using Think Aloud in Health Assessment: A Mixed-Methods Study
Authors: Verkuyl Margaret , Hughes Michelle , Fyfe Mary Clare
Published: November 2018

Background:

Health assessment courses are foundational to prepare students in nursing baccalaureate programs for clinical practice. Nurse educators are interested in testing strategies to improve students' ability to perform physical assessment techniques.

Method:

A mixed-methods design was used to examine nursing students' experiences with the Think Aloud (TA) approach and its affect on their ability and perceived self-efficacy when performing physical assessment skills.

Results:

The participants in the TA intervention group made significant pre–post self-efficacy score gains and had higher focused physical examination marks. There was no significant difference in pre–post self-efficacy scores with the control group. A focus group yielded the following themes: benefits of TA, student challenges, and transferring physical assessment skills to practice.

Conclusion:

The TA approach encourages students to focus on the critical steps in physical assessment skills aiding memory, knowledge gains and preparation for practical testing, and transition to clinical practice. [
J Nurs Educ
. 2018;57(11):684–686.]
Mitochondrial Deacetylase SIRT3 Plays an Important Role in Donor T Cell Responses after Experimental Allogeneic Hematopoietic Transplantation
Authors: Toubai Tomomi , Tamaki Hiroya , Peltier Daniel C. , Rossi Corinne , Oravecz-Wilson Katherine , Liu Chen , Zajac Cynthia , Wu Julia , Sun Yaping , Fujiwara Hideaki , Henig Israel , Kim Stephanie , Lombard David B. , Reddy Pavan
Published: November 2018

Allogeneic hematopoietic cell transplantation (allo-HCT) through its graft-versus-tumor (GVT) effects is a curative therapy against many hematological malignancies. However, GVT is linked to harmful graft-versus-host disease (GVHD) after allo-HCT. Both GVT and GVHD require allogeneic T cell responses, which is an energetically costly process that causes oxidative stress. Sirtuin 3 (SIRT3), a mitochondrial histone deacetylase (HDAC), plays an important role in cellular processes through inhibition of reactive oxygen species (ROS). Nonmitochondrial class of HDACs regulate T cell responses, but the role of mitochondrial HDACs, specifically SIRT3, on donor T cell responses after allo-HCT remains unknown. In this study, we report that SIRT3-deficient (SIRT3−/−) donor T cells cause reduced GVHD severity in multiple clinically relevant murine models. The GVHD protective effect of allogeneic SIRT3−/− T cells was associated with a reduction in their activation, reduced CXCR3 expression, and no significant impact on cytokine secretion or cytotoxic functions. Intriguingly, the GVHD protective effect of SIRT3−/− T cells was associated with a reduction in ROS production, which is contrary to the effect of SIRT3 deficiency on ROS production in other cells/tissues and likely a consequence of their deficient activation. Notably, the reduction in GVHD in the gastrointestinal tract was not associated with a substantial reduction in the GVT effect. Collectively, these data reveal that SIRT3 activity promotes allogeneic donor T cell responses and ROS production without altering T cell cytokine or cytolytic functions and identify SIRT3 as a novel target on donor T cells to improve outcomes after allo-HCT.
T Regulatory Cell Subpopulations Associated with Recent Ultraviolet Radiation Exposure in a Skin Cancer Screening Cohort
Authors: Hesterberg Rebecca S. , Amorrortu Rossybelle P. , Zhao Yayi , Hampras Shalaka , Akuffo Afua A. , Fenske Neil , Cherpelis Basil , Balliu Juliana , Vijayan Laxmi , Epling-Burnette Pearlie K. , Rollison Dana E.
Published: November 2018

UV radiation (UVR) causing DNA damage is a well-documented risk factor for nonmelanoma skin cancer. Although poorly understood, UVR may also indirectly contribute to carcinogenesis by promoting immune evasion. To our knowledge, we report the first epidemiological study designed to investigate the association between quantitative measures of UVR, obtained using a spectrophotometer, and circulating T regulatory (Treg) cells. In addition to total Treg cells, the proportion of functionally distinct Treg cell subsets defined by CD45RA and CD27 phenotypic markers, graded expression of FOXP3 and CD25, and those expressing cutaneous lymphocyte–associated Ag and the chemokine receptor CCR4 were enumerated in 350 individuals undergoing routine skin cancer screening exams and determined not to have prevalent skin cancer. No associations were identified for UVR exposure or the overall proportion of circulating Treg cells; however, Treg cell subpopulations with an activation-associated phenotype, CD45RA−/CD27−, and those expressing cutaneous homing receptors were significantly positively associated with UVR. These subpopulations of Treg cells also differed by age, sex, and race. After stratification by natural skin tone, and adjusting for age and sex, we found that spectrophotometer-based measures of UVR exposure, but not self-reported measures of past sun exposure, were positively correlated with the highest levels of these Treg cell subpopulations, particularly among lighter-skinned individuals. Findings from this large epidemiologic study highlight the diversity of human Treg cell subpopulations associated with UVR, thus raising questions about the specific coordinated expression of CD45RA, CD27, CCR4, and cutaneous lymphocyte–associated Ag on Treg cells and the possibility that UVR contributes to nonmelanoma skin cancer carcinogenesis through Treg cell–mediated immune evasion.
Prediking as kommunikasie
Authors: Beukes M.J. Du P.
Published: November 2018

No abstract available.
Vyftig jaar kerk, teologie en universiteit
Authors: Oberholzer J.P.
Published: November 2018

No abstract available.
Boekbespreking
Authors: Van der Westhuizen H.G. , Botha S.J.
Published: November 2018

No abstract available.
Realization of aperiodic subshifts and uniform densities in groups
Authors: Aubrun Nathalie , Barbieri Sebastián , Thomassé Stéphan
Published: November 2018

A theorem of Gao, Jackson and Seward, originally conjectured to be false by Glasner and Uspenskij, asserts that every countable group admits a 2-coloring. A direct consequence of this result is that every countable group has a strongly aperiodic subshift on the alphabet

\{0,1\}

. In this article, we use Lovász local lemma to first give a new simple proof of said theorem, and second to prove the existence of a

G

-effectively closed strongly aperiodic subshift for any finitely generated group

G

. We also study the problem of constructing subshifts which generalize a property of Sturmian sequences to finitely generated groups. More precisely, a subshift over the alphabet

\{0,1\}

has uniform density

\alpha \in [0,1]

if for every configuration the density of 1's in any increasing sequence of balls converges to

\alpha

. We show a slightly more general result which implies that these subshifts always exist in the case of groups of subexponential growth.
Topological full groups of minimal subshifts and the classification problem for finitely generated complete groups
Authors: Thomas Simon
Published: November 2018

Using results on the structure of the topological full groups ofminimal subshifts, we prove that the isomorphism relation on the space of finitely generated complete groups is not smooth.
Entropy inequalities for factors of IID
Authors: Backhausz Ágnes , Gerencsér Balázs , Harangi Viktor
Published: November 2018

This paper is concerned with certain invariant random processes (called
factors of IID
) on infinite trees. Given such a process, one can assign entropies to different finite subgraphs of the tree. There are linear inequalities between these entropies that hold for any factor of IID process (e.g. “edge versus vertex” or “star versus edge”). These inequalities turned out to be very useful: they have several applications already, the most recent one is the Backhausz–Szegedy result on the eigenvectors of random regular graphs.

We present new entropy inequalities in this paper. In fact, our approach provides a general “recipe” for how to find and prove such inequalities. Our key tool is a generalization of the edge-vertex inequality for a broader class of factor processes with fewer symmetries.
Additional global climate cooling by clouds due to ice crystal complexity
Authors: Järvinen Emma , Jourdan Olivier , Neubauer David , Yao Bin , Liu Chao , Andreae Meinrat O. , Lohmann Ulrike , Wendisch Manfred , McFarquhar Greg M. , Leisner Thomas , Schnaiter Martin
Published: November 2018

Abstract. Ice crystal submicron structures have a large impact on the optical
properties of cirrus clouds and consequently on their radiative effect.
Although there is growing evidence that atmospheric ice crystals are rarely
pristine, direct in situ observations of the degree of ice crystal complexity
are largely missing. Here we show a comprehensive in situ data set of ice
crystal complexity coupled with measurements of the cloud angular scattering
functions collected during a number of observational airborne campaigns at
diverse geographical locations. Our results demonstrate that an overwhelming
fraction (between 61 % and 81 %) of atmospheric ice crystals sampled
in the different regions contain mesoscopic deformations and, as a
consequence, a similar flat and featureless angular scattering function is
observed. A comparison between the measurements and a database of optical
particle properties showed that severely roughened hexagonal aggregates
optimally represent the measurements in the observed angular range. Based on
this optical model, a new parameterization of the cloud bulk asymmetry factor
was introduced and its effects were tested in a global climate model. The
modelling results suggest that, due to ice crystal complexity, ice-containing
clouds can induce an additional short-wave cooling effect of
−1.12 W m2 on the top-of-the-atmosphere radiative budget that has
not yet been considered.
Trends and trend reversal detection in two decades of tropospheric NO2 satellite observations
Authors: Georgoulias Aristeidis K. , van der A Ronald J. , Stammes Piet , Boersma K. Folkert , Eskes Henk J.
Published: November 2018

Abstract. In this work, a ~ 21-years self-consistent global dataset from four different satellite sensors with a mid-morning overpass (GOME/ERS-2, SCIAMACHY/ENVISAT, GOME-2/Metop-A and GOME-2/Metop-B) is compiled to study the long-term tropospheric NO2 patterns and trends. The GOME and GOME-2 data are corrected relative to the SCIAMACHY data in order to reproduce what SCIAMACHY would measure if it was in orbit for the period 4/1996–9/2017. The highest tropospheric NO2 concentrations are seen over urban, industrialized and highly populated areas and over ship tracks in the oceans. Tropospheric NO2 has generally decreased during the last two decades over the industrialized and highly populated regions of the Western World (e.g. average decrease of the order of ~ 49 % over the U.S., the Netherlands and the U.K., ~ 36 % over Italy and Japan and ~ 32 % over Germany and France) and increased over developing regions (e.g. average increase of ~ 160 % over China and ~ 33 % over India). It is suggested here that linear trends cannot be used efficiently worldwide for such long periods. Tropospheric NO2 is very sensitive to socioeconomic changes (e.g. environmental protection policies, economic recession, warfare, etc.) which may cause either short term changes or even a reversal of the trends. The application of a method capable of detecting the year when a reversal of trends happened shows that tropospheric NO2 concentrations switched from positive to negative trends and vice versa over several regions around the globe. A country-level analysis revealed clusters of countries that exhibit similar positive-to-negative or negative-to-positive reversals while 29 out of a total of 64 examined megacities and large urban agglomerations experienced a trend reversal at some point within the last two decades.
Ideas and perspectives: Tree–atmosphere interaction responds to water-related stem variations
Authors: van Emmerik Tim , Steele-Dunne Susan , Gentine Pierre , Oliveira Rafael S. , Bittencourt Paulo , Barros Fernanda , van de Giesen Nick
Published: November 2018

Abstract. Land–atmosphere interactions depend on momentum transfer from the atmosphere
to the canopy, which in turn depends on the tree drag coefficient. It is
known that the drag coefficient, and thus tree–atmosphere momentum transfer,
can vary strongly within a canopy. Yet, only few measurements are available
to study the variation of tree–atmosphere momentum transfer in time and
space, and in response to tree water deficit. In this paper we use
accelerometers to estimate tree–atmosphere momentum transfer for 19
individual trees of 7 different species in the Brazilian Amazon. The 5-month
monitoring period included the transition from wet to dry months. Here, we
demonstrate that, under field conditions, tree–atmosphere momentum transfer
can vary considerably in time and space (up to a factor of 2.5). Increased
water-related stem variations during the dry months are related to observed
changes in tree–atmosphere momentum transfer, which is hypothesized to be
caused by tree-water-deficit-induced changes in tree mass.
Evaluation of atmospheric nitrogen inputs into marine ecosystems of the North Sea and Baltic Sea – part B: contribution by shipping and agricultural emissions
Authors: Neumann Daniel , Radtke Hagen , Karl Matthias , Neumann Thomas
Published: November 2018

Abstract. Atmospheric nitrogen deposition constitutes 20 % to 40 % of the nitrogen input into the North Sea and the Baltic Sea contributing to phytoplankton growth and inducing eutrophication. Major contributors to the atmospheric nitrogen emissions in the vicinity of marine water bodies are shipping and agricultural activities. The contribution of individual emission sectors to the biogeochemical nitrogen cycle needs to be evaluated in order to assess improvement of marine water quality through emission reductions of these sectors. Hence, one focus of this modeling study was to evaluate the contribution of total, shipping-related, and agricultural-related nitrogen deposition to dissolved inorganic nitrogen (DIN), particulate organic nitrogen (PON), chlorophyll-a. A second focus of this study was to compare both water bodies with respect to the accumulation and processing of nitrogen from the mentioned sources. These two research questions were evaluated by a modeling study with the coupled physical-biogeochemical model HBM-ERGOM. The fate of atmospheric deposition in total and of atmospheric nitrogen deposition from two individual sources – shipping and agricultural activities – was traced in the marine ecosystem by a tagging method. In the Baltic Sea it was found that the atmospheric nitrogen deposition contributes up to 50 % to the DIN pool at individual locations during summer. On annual average, 13 % are contributed. Approximately 5 % of DIN originated from agricultural activities and 2 % from the shipping sector. In the western and central Baltic Sea, the shipping sector contributed nearly 5 %. The pattern was similar for the agricultural share indicating that these two sources have a higher relevance in these regions. In the Baltic Sea, the atmospheric nitrogen shares of chlorophyll-a and bioavailable PON were 19 % and 18 %, respectively, and, hence, higher than of DIN. In contrast in offshore regions only, atmospheric nitrogen shares to DIN, PON, and chlorophyll-a were on a similar level compared to each other (20 % to 35 %). This difference is caused by high DIN loads and phosphorus limitation in coastal regions of the Baltic Sea. In the North Sea, the atmospheric contribution to DIN was on a similar level but showed considerable spatial variability caused by a north-south gradient. The shipping contribution to DIN was slightly lower (approximately 1.4 %) and the agricultural contribution higher (6 %) compared to the Baltic Sea. The atmospheric contribution to chlorophyll-a and bioavailable PON was considerably lower than in the Baltic Sea and on the level of the atmospheric DIN shares, which is a result of short residence times of nutrients in the North Sea compared to the Baltic Sea. The shipping and agricultural contributions to PON and chlorophyll-a were also lower.
Residential self-selection in quasi-experimental and natural experimental studies: An extended conceptualization of the relationship between the built environment and travel behavior
Authors: Heinen Eva , Wee Bert van , Panter Jenna , Mackett Roger , Ogilvie David
Published: November 2018

Despite a large body of research suggesting that the built environment influences individual travel behavior, uncertainty remains about the true nature, size, and strength of any causal relationships between the built environment and travel behavior. Residential self-selection, the phenomenon whereby individuals or households select a residential area based on their transport attitudes, is a frequently proposed alternative explanation for the reported associations. To resolve the issue of residential self-selection, longitudinal studies are often recommended.
In this paper, we argue that intervention study designs are insufficient to fully resolve the problem and that intervention studies on the built environment and travel behavior may still be biased by residential self-selection. The aim of this paper is to extend existing conceptualizations of the relationships between the built environment, travel behavior, and attitudes and to provide suggestions for how a causal relationship between the built environment and travel behavior may be ascertained with more accurate estimates of effect sizes. We discuss the complexities of determining causal effects in intervention studies with participants who relocate, and the biases that may occur. We illustrate the complexities by presenting extended conceptualizations. Based on these conceptualizations, we provide considerations for future research. We suggest repeating analyses with and without individuals who relocated during the study, and with and without statistical controls for residential relocation. Additional quantitative and qualitative analyses will be necessary to obtain more accurate effect size estimates and a better understanding of the causal relationships.
Sport, politique, constructions identitaires en Guyane
Authors: Collomb Gérard
Published: November 2018

En quelques années, ledjokan(un art martial que son inventeur présente comme « une fusion des arts guerriers et des pratiques traditionnelles amérindiennes, businenge et créoles ») a acquis en Guyane une grande lisibilité dans les médias mais aussi dans le champ politique, alors même qu’il peine à recruter des pratiquants et que son développement comme sport demeure encore très incertain. Cette situation interroge la manière avec laquelle le champ des pratiques martiales se développe, est mis en forme et structuré dans les pays occidentaux, mais elle est aussi l’occasion de porter un éclairage indirect sur les logiques traversant la société guyanaise. Il faut pour cela prendre en compte la manière avec laquelle le discours dont ledjokanest porteur est en quelque sorte entré en résonnance avec les attentes, parfois les inquiétudes, d’une société qui tente de repenser un « vivre-ensemble » dans une Guyane en mutation.
Lorsque les oiseaux donnent le rythme
Authors: Laugrand Frédéric B. , Laugrand Antoine , Tremblay Guy
Published: November 2018

Les Blaans de Little Baguio vivent d’agriculture et de chasse dans des montagnes situées au sud-est de l’île de Mindanao (Philippines). Ils ont été exposés au christianisme, mais ont conservé nombre de leurs traditions. Les auteurs se concentrent ici sur les connaissances et les relations que les Blaans entretiennent avec les oiseaux qui les entourent. Ils montrent que les oiseaux structurent leur temporalité – en particulier la cosmogonie et la vie quotidienne –, et définissent en partie leurs rituels et leurs règles sociales. Considérés comme d’anciens humains, les oiseaux constituent des médiateurs qui relient mieux que d’autres animaux les mondes visible et invisible. Dans cette perspective, les Blaans ne cherchent pas tant à prédire ou à prévoir l’avenir qu’à suivre les rythmes que leur donnent les oiseaux.
Plasmodium-specific atypical memory B cells are short-lived activated B cells
Authors: Pérez-Mazliah Damián , Gardner Peter J , Schweighoffer Edina , McLaughlin Sarah , Hosking Caroline , Tumwine Irene , Davis Randall S , Potocnik Alexandre J , Tybulewicz Victor LJ , Langhorne Jean
Published: November 2018

A subset of atypical memory B cells accumulates in malaria and several infections, autoimmune disorders and aging in both humans and mice. It has been suggested these cells are exhausted long-lived memory B cells, and their accumulation may contribute to poor acquisition of long-lasting immunity to certain chronic infections, such as malaria and HIV. Here, we generated an immunoglobulin heavy chain knock-in mouse with a BCR that recognizes MSP1 of the rodent malaria parasite, Plasmodium chabaudi. In combination with a mosquito-initiated P. chabaudi infection, we show that Plasmodium-specific atypical memory B cells are short-lived and disappear upon natural resolution of chronic infection. These cells show features of activation, proliferation, DNA replication, and plasmablasts. Our data demonstrate that Plasmodium-specific atypical memory B cells are not a subset of long-lived memory B cells, but rather short-lived activated cells, and part of a physiologic ongoing B-cell response.
Altered hippocampal interneuron activity precedes ictal onset
Authors: Miri Mitra L , Vinck Martin , Pant Rima , Cardin Jessica A
Published: November 2018

Although failure of GABAergic inhibition is a commonly hypothesized mechanism underlying seizure disorders, the series of events that precipitate a rapid shift from healthy to ictal activity remain unclear. Furthermore, the diversity of inhibitory interneuron populations poses a challenge for understanding local circuit interactions during seizure initiation. Using a combined optogenetic and electrophysiological approach, we examined the activity of identified mouse hippocampal interneuron classes during chemoconvulsant seizure induction in vivo. Surprisingly, synaptic inhibition from parvalbumin- (PV) and somatostatin-expressing (SST) interneurons remained intact throughout the preictal period and early ictal phase. However, these two sources of inhibition exhibited cell-type-specific differences in their preictal firing patterns and sensitivity to input. Our findings suggest that the onset of ictal activity is not associated with loss of firing by these interneurons or a failure of synaptic inhibition but is instead linked with disruptions of the respective roles these interneurons play in the hippocampal circuit.
Structure, dynamics and predicted functional role of the gut microbiota of the blue (Haliotis fulgens) and yellow (H. corrugata) abalone from Baja California Sur, Mexico
Authors: Cicala Francesco , Cisterna-Céliz José Alejandro , Moore James D. , Rocha-Olivares Axayácatl
Published: November 2018

The GI microbiota of abalone contains a highly complex bacterial assemblage playing an essential role in the overall health of these gastropods. The gut bacterial communities of abalone species characterized so far reveal considerable interspecific variability, likely resulting from bacterial interactions and constrained by the ecology of their abalone host species; however, they remain poorly investigated. Additionally, the extent to which structural changes in the microbiota entail functional shifts in metabolic pathways of bacterial communities remains unexplored. In order to address these questions, we characterized the gut microbiota of the northeast Pacific blue (Haliotis fulgensor HF) and yellow (Haliotis corrugataor HC) abalone by16S rRNAgene pyrosequencing to shed light on: (i) their gut microbiota structure; (ii) how bacteria may interact among them; and (iii) predicted shifts in bacterial metabolic functions associated with the observed structural changes. Our findings revealed thatMycoplasmadominated the GI microbiome in both species. However, the structure of the bacterial communities differed significantly in spite of considerable intraspecific variation. This resulted from changes in predominant species composition in each GI microbiota, suggesting host-specific adaptation of bacterial lineages to these sympatric abalone. We hypothesize that the presence of exclusive OTUs in each microbiota may relate to host-specific differences in competitive pressure. Significant differences in bacterial diversity were found between species for the explored metabolic pathways despite their functional overlap. A more diverse array of bacteria contributed to each function in HC, whereas a single or much fewer OTUs were generally observed in HF. The structural and functional analyses allowed us to describe a significant taxonomic split and functional overlap between the microbiota of HF and HC abalone.
imGLAD: accurate detection and quantification of target organisms in metagenomes
Authors: Castro Juan C. , Rodriguez-R Luis M. , Harvey William T. , Weigand Michael R. , Hatt Janet K. , Carter Michelle Q. , Konstantinidis Konstantinos T.
Published: November 2018

Accurate detection of target microbial species in metagenomic datasets from environmental samples remains limited because the limit of detection of current methods is typically inaccessible and the frequency of false-positives, resulting from inadequate identification of regions of the genome that are either too highly conserved to be diagnostic (e.g., rRNA genes) or prone to frequent horizontal genetic exchange (e.g., mobile elements) remains unknown. To overcome these limitations, we introduce imGLAD, which aims to detect (target) genomic sequences in metagenomic datasets. imGLAD achieves high accuracy because it uses the sequence-discrete population concept for discriminating between metagenomic reads originating from the target organism compared to reads from co-occurring close relatives, masks regions of the genome that are not informative using the MyTaxa engine, and models both the sequencing breadth and depth to determine relative abundance and limit of detection. We validated imGLAD by analyzing metagenomic datasets derived from spinach leaves inoculated with the enteric pathogen Escherichia coli O157:H7 and showed that its limit of detection can be comparable to that of PCR-based approaches for these samples (∼1 cell/gram).
A trait-based ecology to assess the acclimation of a sperm-dependent clonal fish compared to its sexual host
Authors: Leung Christelle , Breton Sophie , Angers Bernard
Published: November 2018

Background

Survival in temporally or spatially changing environments is a prerequisite for the perpetuation of a given species. In addition to genetic variation, the role of epigenetic processes is crucial in the persistence of organisms. For instance, mechanisms such as developmental flexibility enable the adjustment of the phenotype of a given individual to changing conditions throughout its development. However, the extent of factors other than genetic variability, like epigenetic processes, in the production of alternative phenotype and the consequences in realized ecological niches is still unclear.

Methods

In this study, we compared the extent of realized niches between asexual and sexual individuals from different environments. We used a trait-based ecology approach exploiting trophic and locomotive structures to infer the environment that each biotype actually used. More specifically, we compared the morphology of the all-female clonal and sperm-dependent fishChrosomus eos-neogaeusto that of their sexual host speciesC. eosin common garden and natural conditions.

Results

Transfer from natural to controlled conditions resulted in a similar shift in measured morphology for clonal and sexual individuals suggesting comparable level of flexibility in both kinds of organisms. However, clonal, but not sexual, individuals displayed a consistent phenotype when reared in uniform conditions indicating that in absence of genetic variation, one phenotype corresponds to one niche. This contrasted with results from natural conditions where clones were morphologically as variable as sexual individuals within a sampled site. In addition, similar phenotypic changes for both clonal and sexual individuals were observed among the majority of sampled sites, indicating that they responded similarly to the same environments.

Discussion

Our results indicated that clones can efficiently use different niches and may evolve in a range of environmental conditions comparable to that of a sexual species, thus underlying the importance of factors other than genetic variability, like epigenetic processes, for coping with environmental heterogeneity.
Election Night
Authors: Beck Andrew F.
Published: November 2024

While watching the 2024 election night results and considering possible health care policies, a pediatrician reflects on his role in engaging in conversations about politics and policy as an advocate for patients.