bluuebunny/crossref_metadata_2025 huggingface dataset:
Strong wave–mean-flow coupling in baroclinic acoustic streaming
Authors: Michel Guillaume , Chini Gregory P.
Published: November 2018

The interaction of an acoustic wave with a stratified fluid can drive strong streaming flows owing to the baroclinic production of fluctuating vorticity, as recently demonstrated by Chini et al. (J. Fluid Mech., 744, 2014, pp. 329–351). In the present investigation, a set of wave/mean-flow interaction equations is derived that governs the coupled dynamics of a standing acoustic-wave mode of characteristic (small) amplitude $\unicode[STIX]{x1D716}$ and the streaming flow it drives in a thin channel with walls maintained at differing temperatures. Unlike classical Rayleigh streaming, the resulting mean flow arises at $O(\unicode[STIX]{x1D716})$ rather than at $O(\unicode[STIX]{x1D716}^{2})$. Consequently, fully two-way coupling between the waves and the mean flow is possible: the streaming is sufficiently strong to induce $O(1)$ rearrangements of the imposed background temperature and density fields, which modifies the spatial structure and frequency of the acoustic mode on the streaming time scale. A novel Wentzel–Kramers–Brillouin–Jeffreys analysis is developed to average over the fast wave dynamics, enabling the coupled system to be integrated strictly on the slow time scale of the streaming flow. Analytical solutions of the reduced system are derived for weak wave forcing and are shown to reproduce results from prior direct numerical simulations (DNS) of the compressible Navier–Stokes and heat equations with remarkable accuracy. Moreover, numerical simulations of the reduced system are performed in the regime of strong wave/mean-flow coupling for a fraction of the computational cost of the corresponding DNS. These simulations shed light on the potential for baroclinic acoustic streaming to be used as an effective means to enhance heat transfer.
Team Leaders Matter in Knowledge Sharing: A Cross-Level Analysis of the Interplay between Leaders’ and Members’ Goal Orientations in the Chinese Context
Authors: Zhang Jiamin , Wang Yi , Zhang Marina Yue
Published: November 2018

This article investigates the impact of cross-level interplay between team members’ and their leaders’ goal orientations (learning, performance approach, and performance avoidance) on knowledge sharing using samples from design teams in two companies in China. Our results show that team leaders’ learning goal orientation plays a critical moderating role. Specifically, team leaders’ learning goal orientation strengthens the positive relationship between team members’ learning orientation and knowledge sharing; positively moderates the relationship between team members’ performance approach orientation and knowledge sharing; and weakens the negative relationship between team members’ performance avoidance orientation and knowledge sharing. Team leaders’ performance approach orientation demonstrates a positive moderating effect when there is congruence between the performance approach orientation of leaders and members. Finally, team leaders’ performance avoidance orientation negatively moderates the relationship between team members’ learning and performance approach orientation on knowledge sharing. This research enhances our understanding of the conditions under which knowledge sharing occurs among team members, using the lens of Trait Activation Theory.
Hyper-longirostry and kinematic disparity in extinct toothed whales
Authors: McCurry Matthew R. , Pyenson Nicholas D.
Published: November 2018

Toothed cetacean (Odontoceti) lineages in the Miocene and Pliocene evolved rostra that are proportionally more elongate than any other aquatic mammal or reptile, living or extinct. Their similarities in cranial proportions to billfish may suggest a convergent feeding style, where the rostrum is swept through the water to hit and stun prey. Here we calculated second moment of area from rostral cross sections of these fossil odontocete taxa, as well as from extant ecological analogues, to infer variation in feeding behavior. Our results show that the extremely long rostra of extinct toothed whales vary considerably in functionally relevant measures of shape and likely exhibited a diversity of feeding behaviors, ranging from those similar to modern odontocetes to those convergent with billfish. Eustatic sea-level and temperature maxima of the Miocene likely led to changes in prey characteristics or abundance that enabled the repeated evolution of this extreme morphotype, which later went extinct during late Pliocene climatic deterioration.
How conceptualizing influences fluency in first and second language speech production
Authors: FELKER EMILY R. , KLOCKMANN HEIDI E. , DE JONG NIVJA H.
Published: November 2018

When speaking in any language, speakers must conceptualize what they want to say before they can formulate and articulate their message. We present two experiments employing a novel experimental paradigm in which the formulating and articulating stages of speech production were kept identical across conditions of differing conceptualizing difficulty. We tracked the effect of difficulty in conceptualizing during the generation of speech (Experiment 1) and during the abandonment and regeneration of speech (Experiment 2) on speaking fluency by Dutch native speakers in their first (L1) and second (L2) language (English). The results showed that abandoning and especially regenerating a speech plan taxes the speaker, leading to disfluencies. For most fluency measures, the increases in disfluency were similar across L1 and L2. However, a significant interaction revealed that abandoning and regenerating a speech plan increases the time needed to solve conceptual difficulties while speaking in the L2 to a greater degree than in the L1. This finding supports theories in which cognitive resources for conceptualizing are shared with those used for later stages of speech planning. Furthermore, a practical implication for language assessment is that increasing the conceptual difficulty of speaking tasks should be considered with caution.
COMBINING ESTIMATES OF CONDITIONAL TREATMENT EFFECTS
Authors: Rolling Craig A. , Yang Yuhong , Velez Dagmar
Published: November 2018

Estimating a treatment’s effect on an outcome conditional on covariates is a primary goal of many empirical investigations. Accurate estimation of the treatment effect given covariates can enable the optimal treatment to be applied to each unit or guide the deployment of limited treatment resources for maximum program benefit. Applications of conditional treatment effect estimation are found in direct marketing, economic policy, and personalized medicine. When estimating conditional treatment effects, the typical practice is to select a statistical model or procedure based on sample data. However, combining estimates from the candidate procedures often provides a more accurate estimate than the selection of a single procedure. This article proposes a method of model combination that targets accurate estimation of the treatment effect conditional on covariates. We provide a risk bound for the resulting estimator under squared error loss and illustrate the method using data from a labor skills training program.
Nutrition risk among an ethnically diverse sample of community-dwelling older adults
Authors: Sheean Patricia , Farrar Isabel C , Sulo Suela , Partridge Jamie , Schiffer Linda , Fitzgibbon Marian
Published: November 2018

Objective

To assess the prevalence of nutritional risk among an ethnically diverse group of urban community-dwelling older adults and to explore if risk varied by race/ethnicity.

Design

Demographic characteristics, Katz’s activities of daily living and health-care resource utilization were ascertained cross-sectionally via telephone surveys with trained interviewers. Nutrition risk and nutrition symptomology were assessed via the abridged Patient Generated Subjective Global Assessment (abPG-SGA); scores of ≥6 points delineated ‘high’ nutrition risk. Descriptive statistics and logistic regression analyses were conducted.

Setting

Urban.

Participants

White, Black or Hispanic community-dwelling adults, ≥55 years of age, fluent in English or Spanish, residing in the city limits of Chicago, IL, USA.

Results

A total of 1001 participants (37 % white, 37 % Black, 26 % Hispanic) were surveyed. On average, participants were 66·9 years old, predominantly female and overweight/obese. Twenty-six per cent (n 263) of participants were classified as ‘high’ nutrition risk with 24, 14 and 31 % endorsing decreased oral intake, weight loss and compromised functioning, respectively. Black respondents constituted the greatest proportion of those with high risk scores, yet Hispanic participants displayed the most concerning nutrition risk profiles. Younger age, female sex, Black or Hispanic race/ethnicity, emergency room visits, eating alone and taking three or more different prescribed or over-the-counter drugs daily were significantly associated with high risk scores (P<0·05).

Conclusions

One in four older adults living in an urban community prone to health disparities was classified as ‘high’ nutrition risk. Targeted interventions to promote healthy ageing are needed, especially for overweight/obese and minority community members.
Infant and young child feeding practices, sociodemographic factors and their association with nutritional status of children aged <3 years in India: findings of the National Nutrition Monitoring Bureau survey, 2011–2012
Authors: Meshram Indrapal Ishwarji , Mallikharjun Rao K , Balakrishna Nagalla , Harikumar R , Arlappa N , Sreeramakrishna Kakani , Laxmaiah Avula
Published: November 2018

Objective

To study infant and young child feeding (IYCF) practices and their association with nutritional status among young children.

Design

A community-based, cross-sectional study was carried out in ten states of India, using a multistage random sampling method. Anthropometric measurements such as length/height and weight were conducted and nutritional assessment was done using the WHO child growth standards.

Setting

National Nutrition Monitoring Bureau survey, 2011–2012.

Participants

Children aged <3 years and their mothers.

Results

Only 36 % of infants received breast-feeding within an hour of birth and 50 % were exclusively breast-fed up to 6 months. Prevalence of underweight, stunting and wasting was 38, 41 and 22 %, respectively. The chance of undernutrition among <3-year-old children was significantly higher among those from scheduled caste/scheduled tribe communities, the lowest-income group, with illiterate mothers and lack of sanitary latrine. Among infants, the chance of undernutrition was significantly higher among low-birth-weight babies, and among children whose mother had not consumed iron–folic acid tablets during pregnancy. Immunization practices and minimum dietary diversity were observed to be associated with undernutrition among 12–23-month-old children.

Conclusions

Undernutrition is still an important public health problem in India and observed to be associated with low socio-economic status, illiteracy of mother, low birth weight and dietary diversity. Improving socio-economic and literacy status of mothers can help in improving maternal nutrition during pregnancy and thus low birth weight. Also, improving knowledge of mothers about IYCF practices will help in improving children’s nutritional status.
In praise of outlaws
Authors: King Rachel
Published: November 2018

‘Outlaw’ is not a common category of archaeological thought but it is perhaps more useful than meets the eye. ‘Outlaws’ are typically viewed as contingent on legal and capitalist systems; they are, I suggest, also material, affective phenomena that draw our attention to how transgression, dissent and disorder are conceived through archaeological thinking. Here, I outline some ways in which ‘outlaw’ figures are ‘good to think with’, particularly for historical and colonial contexts but also for broader, more global frontier situations. Through three sketches of archetypal ‘outlaws’ in southern Africa's recent past, I consider where these disruptive figures draw attention to how mobility, violence, rebellion and state imagination (and the limits thereof) have been imagined through material misbehaviours.
The perils of ethnographic analogy. Parallel logics in ethnoarchaeology and Victorian Bible customs books
Authors: Cunningham Jerimy J. , McGeough Kevin M.
Published: November 2018

In recent years, ethnoarchaeology and the use of ethnographic analogy have come under increasing criticism. Analogy seems necessary because, as post-industrial academics, archaeologists worry that they do not possess the knowledge necessary to interpret archaeological materials directly and thus must consult with coeval ‘premodern’ peoples to develop interpretive baselines. In this paper, we draw attention to a form of scholarly enquiry – 19th-century Bible customs books – that faced a similar challenge and used methodologies that parallel archaeology's use of ethnoarchaeological data. These were books written by missionaries who lived in Palestine for extended periods of time and studied Palestinian life to make sense of obscure elements of the biblical text, believing that life there had remained fundamentally unchanged for the past three thousand years. Using the Bible customs books as a kind of ‘cautionary tale’ typical of ethnoarchaeology, we argue that a consideration of this literature brings into focus some of the challenges faced by archaeologists’ use of analogy. Specifically, Bible customs books expose significant issues in how relations are conceptualized between archaeologists, others and ancients, and show how a strict empirical focus in ethnographic research can insulate key assumptions from critical scrutiny.
A taphonomy of a dark Anthropocene. A response to Þóra Pétursdóttir's OOO-inspired ‘Archaeology and Anthropocene’
Authors: Ion Alexandra
Published: November 2018

Þóra Pétursdóttir raises the point that archaeology is limited regarding what it can achieve, including the challenges posed by the Anthropocene, by a series of theoretical assumptions. She challenges the ‘traditional’ archaeological ‘key tropes’ in matters of this new epoch, namely the concepts of culture history, deep time/distant pasts, and the nature–culture divide. Instead, she proposes a number of new guiding points to orient archaeological inquiries, framed as part of the object-oriented ontological (OOO) philosophies. In reply, I claim that the use of OOO theories is rather unhelpful for addressing the topic of the Anthropocene, given that they lead to important ethical and political consequences: a fetishization of things, an abandoning of responsibility and an alienation of humans. They are also based on the confusion that analytical distinctions are in some way the ones responsible for the existence of inequalities, ecological destruction, racism or discrimination. Paradoxically, precisely through their annihilation, there is no room left for acknowledging the alterity of the past.
Ultrastructural Deformities in the Scales of Cyprinus carpio Inhabiting Two Government-Sponsored Fish Farms in North-East India Contaminated by Municipal Wastes and Other Pollutants
Authors: Pala Eva M.
Published: November 2018

Scanning electron microscopy of the scales of Cyprinus carpio, inhabiting two government-sponsored fish farms, with different sources of pollutants, in the North-East state of Meghalaya, India revealed extensive damage to them. Lepidonts, which are teeth-like structures present on the edge of circulii, were discovered to be either partly or completely damaged. The dislodgment of complete rows of lepidonts along with broken lepidonts was also observed. Loss of symmetry and torn areas of circulii are some of the abnormalities also observed as compared to control samples. The alterations observed could be because of the high sensitivity of the scales to environmental stress and their capacity to react to low concentrations of pollutants, which makes them a sensitive bioindicator of water pollution. The study hence not only represents an advance in pollution research, by employing a highly sophisticated analytical approach to reveal the above-mentioned microstructural scale abnormalities, but it can also have scientific impact on the society at large and the fish culturist in particular in understanding the destructive impact of pollution caused by mismanagement of city garbage and agricultural effluents.
Joining of TiAl Alloy Using Novel Ag–Cu Sputtered Coated Ti Brazing Filler
Authors: Simões Sónia , Soares Ana , Tavares Carlos José , Guedes Aníbal
Published: November 2018

The aim of this study is to evaluate the potential use of titanium foil coated with sputtered silver and copper films as a novel brazing filler for joining TiAl alloys. For this purpose, a detailed microstructural characterization of the resulting brazing interfaces was carried out. The development of brazing fillers that allow the joining of TiAl alloys without compromising the service temperature is a fruitful prospect. Brazing experiments were performed in a vacuum at 900, 950, and 980°C, with a dwell time of 30 min. Microstructural characterization reveals that brazing joints can be obtained successfully at 950 and 980°C. The interface consists of a large central region of α-Ti with an amount of Al and Ti–Ag compound and thin layers, mainly composed of intermetallic compounds, formed close to the base material. A novel brazing filler consisting of Ti foil coated with sputtered Ag and Cu films inhibits the extensive formation of soft (Ag) zones or coarse brittle Ti–Al–(Cu,Ni) particles. Hence, the need for post-brazing heat treatments for the joining of TiAl alloys was avoided.
TWO SYLLOGISMS IN THEMOZI: CHINESE LOGIC AND LANGUAGE
Authors: YI BYEONG-UK
Published: November 2018

This article examines two syllogistic arguments contrasted in an ancient Chinese book, theMozi, which expounds doctrines of the Mohist school of philosophers. While the arguments seem to have the same form, one of them (theone-horse argument) is valid but the other (thetwo-horse argument) is not. To explain this difference, the article uses English plural constructions to formulate the arguments. Then it shows that the one-horse argument is valid because it has a valid argument form, the plural cousin of a standard form of valid categorical syllogisms (Plural Barbara), and argues that the two-horse argument involves equivocal uses of a key predicate (the Chinese counterpart of ‘have four feet’) that has the distributive/nondistributive ambiguity. In doing so, the article discusses linguistic differences between Chinese and English and explains why the logic of plural constructions is applicable to Chinese arguments that involve no plural constructions.
Can GNSS Reflectometry Detect Precipitation Over Oceans?
Authors: Asgarimehr Milad , Zavorotny Valery , Wickert Jens , Reich Sebastian
Published: November 2018

For the first time, a rain signature in Global Navigation Satellite System Reflectometry (GNSS‐R) observations is demonstrated. Based on the argument that the forward quasi‐specular scattering relies upon surface gravity waves with lengths larger than several wavelengths of the reflected signal, a commonly made conclusion is that the scatterometric GNSS‐R measurements are not sensitive to the surface small‐scale roughness generated by raindrops impinging on the ocean surface. On the contrary, this study presents an evidence that the bistatic radar cross section σ0 derived from TechDemoSat‐1 data is reduced due to rain at weak winds, lower than ≈ 6 m/s. The decrease is as large as ≈ 0.7 dB at the wind speed of 3 m/s due to a precipitation of 0–2 mm/hr. The simulations based on the recently published scattering theory provide a plausible explanation for this phenomenon which potentially enables the GNSS‐R technique to detect precipitation over oceans at low winds.
Quantifying East Asian Summer Monsoon Dynamics in the ECP4.5 Scenario With Reference to the Mid‐Piacenzian Warm Period
Authors: Sun Yong , Ramstein Gilles , Li Laurent Z. X. , Contoux Camille , Tan Ning , Zhou Tianjun
Published: November 2018

The mid‐Piacenzian (~3.3–3.0 Ma), which was characterized by high pCO2 (~400 ppm) and global surface air temperatures that were 1.84–3.60 °C above pre‐Industrial levels, provides clues to the likely changes in atmospheric dynamics in a future climate affected by anthropogenic warming, although its suitability as an analogue of the future climate has yet to be assessed. This study investigates the extent to which the dynamics of the East Asian summer monsoon during the mid‐Piacenzian can aid our understanding of East Asian summer monsoon behavior in the Extended Concentration Pathway version 4.5 scenario, using water vapor and moist static energy equations. The temperature‐dependent large‐scale moisture transport explains the similar pattern of precipitation increase in the two climates, whereas regional patterns of vertical motion differ significantly. Two of the main terms of the moist static energy equation control the changes in regional dynamics relative to the pre‐Industrial period. These terms relate to zonal advection of stationary eddy dry enthalpy by the mean zonal wind and meridional stationary eddy velocity over East Asia. Topographic differences between the two cases have a negligible effect on regional precipitation.
Evolution of Asymmetrically Displaced Footpoints During Substorms
Authors: Ohma A. , Østgaard N. , Reistad J. P. , Tenfjord P. , Laundal K. M. , Snekvik K. , Haaland S. E. , Fillingim M. O.
Published: November 2018

It is well established that a transverse (y) component in the interplanetary magnetic field (IMF) induces a By component in the closed magnetosphere through asymmetric loading and/or redistribution of magnetic flux. Simultaneous images of the aurora in the two hemispheres have revealed that conjugate auroral features are displaced longitudinally during such conditions. Although the direction and magnitude of this displacement show correlations with IMF clock angle and dipole tilt, single events show large temporal and spatial variability of this displacement. For instance, we know little about how the displacement changes during a substorm. A previous case study demonstrated that displaced auroral forms, associated with the prevailing IMF orientation, returned to a more symmetric configuration during the expansion phase of two substorms. Using the far ultraviolet cameras on board the Imager for Magnetopause‐to‐Aurora Global Exploration and Polar satellites, we have identified multiple events where conjugate auroral images are available during periods with substorm activity and IMF By≠0. We identify conjugate auroral features and investigate how the asymmetry evolves during the expansion phase. We find that the system returns to a more symmetric state in the events with a clear increase in the nightside reconnection rate and that the displacement remains unchanged in the events with little or no net closure of open magnetic flux. The return to a more symmetric state can therefore be interpreted as the result of increased reconnection rate in the magnetotail during the expansion phase, which reduces the asymmetric lobe pressure.
The Study of Momentum, Mass, and Heat Transfer in a Droplet‐Laden Turbulent Airflow Over a Waved Water Surface by Direct Numerical Simulation
Authors: Druzhinin O. A. , Troitskaya Yu. I. , Zilitinkevich S. S.
Published: November 2018

This paper investigates turbulent exchange processes in a droplet‐laden air flow over a waved water surface by performing direct numerical simulation (DNS). Turbulent Couette flow is considered in DNS as a model of a constant‐flux layer in the marine atmospheric surface layer. Two‐dimensional stationary waves at the water surface are prescribed and assumed to be unaffected by the airflow and/or droplets. Evaporating droplets of different sizes are injected into the air in the vicinity of wave crests with initial velocities and temperatures of water, and thus mimicking spume sea‐spray droplets. Evolution equations of the airflow velocity, temperature, and humidity are solved in a Eulerian framework simultaneously with the equations of individual droplets coordinates and velocities, temperatures, and masses tracked in a Lagrangian framework. The momentum (Qm) and sensible (QS) and latent (QL) heat fluxes from the droplets to air are evaluated both as phase‐averaged Eulerian fields and as fluxes integrated over time along Lagrangian droplets trajectories. The results show that droplets extract momentum from the surrounding air (Qm < 0), and QL > 0 and increases with droplet diameter, d, whereas QS < 0, reaches maximum for droplets with diameters of the order of 200 μm, and saturates for larger droplets. The resulting enthalpy flux QS + QL > 0 vanishes for droplets with diameters d < 100 μm, and increases with d for larger droplets. DNS results also show that droplets reduce mean air velocity and temperature and increase relative humidity as compared to the droplet‐free flow.
A New Number Format for Ensemble Simulations
Authors: Düben Peter D.
Published: November 2018

A new number format for ensemble simulations for weather and climate predictions is presented. The new format exploits similarities between ensemble members to reduce overall data usage. Data use and movement is the most important performance bottleneck for weather and climate models on modern supercomputers. The new format can be realized on standard hardware and with standard computing languages such as Fortran. The format is tested in simulations with a shallow water model. Advantages and disadvantages are discussed.
Calibrating HF Radar Elevation Angle Measurements Using E Layer Backscatter Echoes
Authors: Ponomarenko P. , St.‐Maurice J.‐P. , McWilliams K. A.
Published: November 2018

One of the most important observed parameters of the ionospheric radar returns in the high‐frequency range is the vertical arrival angle (elevation angle), which provides information about ionospheric conditions along the propagation path, as well as characterizes the propagation mode of the radio signals. The most advanced network of ionospheric high‐frequency (HF) radars, SuperDARN (Super Dual Auroral Radar Network) utilizes two‐array interferometry to estimate this parameter. However, due to the intrinsic technical difficulties with direct (instrumental) calibration of a time offset between measurements made by the two arrays, td, the SuperDARN elevation angle data have been rarely used in the past. The present work is a further development of the calibration technique recently proposed by Ponomarenko et al. (2015, https://doi.org/10.1186/s40623-015-0310-3), which was based on the well‐defined propagation properties of the F layer ground scatter echoes. The main disadvantage of the original technique is that the F layer propagation conditions may vary considerably, even on a day‐to‐day basis, so its application requires visual analysis of data records. In order to address this issue, the new method utilizes the E layer ionospheric scatter whose range and altitude coverage are much more constrained. This allowed to quantify calibration criteria and to develop an automated procedure for td estimation. The improved technique has been applied to 1 year of data records from the Rankin Inlet SuperDARN radar and has demonstrated the capability for reliable td monitoring on a daily basis. Importantly, the proposed technique does not require access to the radar hardware and allows for calibrating historic data.
Time‐Window Approaches to Space‐Weather Forecast Metrics: A Solar Wind Case Study
Authors: Owens Mathew J.
Published: November 2018

Metrics are an objective, quantitative assessment of forecast (or model) agreement with observations. They are essential for assessing forecast accuracy and reliability and consequently act as a diagnostic for forecast development. Partly as a result of limited spatial sampling of observations, much of space‐weather forecasting is focused on the time domain rather than inherent spatial variability. Thus, metrics are primarily point‐by‐point approaches, in which observed conditions at time t are compared directly (and only) with the forecast conditions at time t. Such metrics are undoubtedly useful. But in lacking an explicit consideration of timing uncertainties, they have limitations as diagnostic tools and can, under certain conditions, be misleading. Using a near‐Earth solar wind speed forecast as an illustrative example, this study briefly reviews the most commonly used point‐by‐point metrics and advocates for complementary time window approaches. In particular, a scale‐selective approach, originally developed in numerical weather prediction for validation of spatially patchy rainfall forecasts, is adapted to the time domain for space‐weather purposes. This simple approach readily determines the time scales over which a forecast is and is not valuable, allowing the results of point‐by‐point metrics to be put in greater context.
Reply to Comment by Pedreira et al. on “Reconstruction of the Exhumed Mantle Across the North Iberian Margin by Crustal‐Scale 3‐D Gravity Inversion and Geological Cross Section”
Authors: Pedrera A. , García‐Senz J. , Ayala C. , Ruiz‐Constán A. , Rodríguez‐Fernández L. R. , Robador A. , González Menéndez L.
Published: November 2018

Key Points

A continuous high‐density body is regarded as exhumed mantle rocks beneath the Basque‐Cantabrian Basin extending along the Northern Pyrenees

Pedreira et al. () doubts our 3‐D gravity model, the view of the high‐density body as exhumed mantle, and the proposed geodynamic model

We defend point by point our model that offers important keys to understand the extension and inversion of the North Iberian Margin
Defective DNA damage repair leads to frequent catastrophic genomic events in murine and human tumors
Authors: Ratnaparkhe Manasi , Wong John K. L. , Wei Pei-Chi , Hlevnjak Mario , Kolb Thorsten , Simovic Milena , Haag Daniel , Paul Yashna , Devens Frauke , Northcott Paul , Jones David T. W. , Kool Marcel , Jauch Anna , Pastorczak Agata , Mlynarski Wojciech , Korshunov Andrey , Kumar Rajiv , Downing Susanna M. , Pfister Stefan M. , Zapatka Marc , McKinnon Peter J. , Alt Frederick W. , Lichter Peter , Ernst Aurélie
Published: November 2018

Chromothripsis and chromoanasynthesis are catastrophic events leading to clustered genomic rearrangements. Whole-genome sequencing revealed frequent complex genomic rearrangements (n = 16/26) in brain tumors developing in mice deficient for factors involved in homologous-recombination-repair or non-homologous-end-joining. Catastrophic events were tightly linked to Myc/Mycn amplification, with increased DNA damage and inefficient apoptotic response already observable at early postnatal stages. Inhibition of repair processes and comparison of the mouse tumors with human medulloblastomas (n = 68) and glioblastomas (n = 32) identified chromothripsis as associated with MYC/MYCN gains and with DNA repair deficiencies, pointing towards therapeutic opportunities to target DNA repair defects in tumors with complex genomic rearrangements.
Author Correction: Division of labour between Myc and G1 cyclins in cell cycle commitment and pace control
Authors: Dong Peng , Maddali Manoj V. , Srimani Jaydeep K. , Thélot François , Nevins Joseph R. , Mathey-Prevot Bernard , You Lingchong
Published: November 2018

This Article contains errors in Supplementary Table 3, which are described in the Author Correction associated with this Article. The simulation results in the Article were based on the correct formula and thus the results are not affected by this correction. The errors have not been fixed in the original Article.
Dynamic Greenland ice sheet driven by pCO2 variations across the Pliocene Pleistocene transition
Authors: Tan Ning , Ladant Jean-Baptiste , Ramstein Gilles , Dumas Christophe , Bachem Paul , Jansen Eystein
Published: November 2018

It is generally considered that the perennial glaciation of Greenland lasting several orbital cycles began around 2.7 Ma along with the intensification of Northern Hemisphere glaciation (NHG). Both data and model studies have demonstrated that a decline in atmospheric pCO2 was instrumental in establishing a perennial Greenland ice sheet (GrIS), yet models have generally used simplistic pCO2 constraints rather than data-inferred pCO2 evolution. Here, using a method designed for the long-term coupling of climate and cryosphere models and pCO2 scenarios from different studies, we highlight the pivotal role of pCO2 on the GrIS expansion across the Plio-Pleistocene Transition (PPT, 3.0–2.5 Ma), in particular in the range between 280 and 320 ppm. Good qualitative agreement is obtained between various IRD reconstructions and some of the possible evolutions of the GrIS simulated by our model. Our results underline the dynamism of the GrIS waxing and waning under pCO2 levels similar to or lower than today, which supports recent evidence of a dynamic GrIS during the Plio-Pleistocene.
Designer liquid-liquid interfaces made from transient double emulsions
Authors: Dockx Greet , Geisel Steffen , Moore David G. , Koos Erin , Studart Andre R. , Vermant Jan
Published: November 2018

Current methods for generating liquid-liquid interfaces with either controlled composition or coverage often rely on adsorption equilibria which limits the freedom to design such multiphase materials, in particular when different components are used. Moreover, when interfaces become densely populated, slowing down of adsorption may impose additional constraints. Up to now, it is not possible to control surface coverage and composition of droplet interfaces at will. Here, we report a generic and versatile method to create designer liquid-liquid interfaces, using transient double emulsions. We demonstrate how the surface coverage in Pickering emulsions can be controlled at will, even for dense particulate layers going up to multilayers. Moreover, composite droplet interfaces with compositional control can be generated, even with particles which would have intrinsically different or even opposite adsorption characteristics. Given its simplicity, this method offers a general approach for control of composition of liquid-liquid interfaces in a variety of multiphase systems.
Two novel, putative mechanisms of action for citalopram-induced platelet inhibition
Authors: Roweth Harvey G. , Cook Aaron A. , Moroi Masaaki , Bonna Arkadiusz M. , Jung Stephanie M. , Bergmeier Wolfgang , Sage Stewart O. , Jarvis Gavin E.
Published: November 2018

Citalopram, a selective serotonin reuptake inhibitor (SSRI), inhibits platelet function in vitro. We have previously shown that this action is independent of citalopram’s ability to block serotonin uptake by the serotonin transporter and must therefore be mediated via distinct pharmacological mechanisms. We now report evidence for two novel and putative mechanisms of citalopram-induced platelet inhibition. Firstly, in platelets, citalopram blocked U46619-induced Rap1 activation and subsequent platelet aggregation, but failed to inhibit U46619-induced increases in cytosolic Ca2+. Similarly, in neutrophils, citalopram inhibited Rap1 activation and downstream functions but failed to block PAF-induced Ca2+ mobilisation. In a cell-free system, citalopram also reduced CalDAG-GEFI-mediated nucleotide exchange on Rap1B. Secondly, the binding of anti-GPVI antibodies to resting platelets was inhibited by citalopram. Furthermore, citalopram-induced inhibition of GPVI-mediated platelet aggregation was instantaneous, reversible and displayed competitive characteristics, suggesting that these effects were not caused by a reduction in GPVI surface expression, but by simple competitive binding. In conclusion, we propose two novel, putative and distinct inhibitory mechanisms of action for citalopram: (1) inhibition of CalDAG-GEFI/Rap1 signalling, and (2) competitive antagonism of GPVI in platelets. These findings may aid in the development of novel inhibitors of CalDAG-GEFI/Rap1-dependent nucleotide exchange and novel GPVI antagonists.
Collective antiskyrmion-mediated phase transition and defect-induced melting in chiral magnetic films
Authors: Pierobon L. , Moutafis C. , Li Y. , Löffler J. F. , Charilaou M.
Published: November 2018

Magnetic phase transitions are a manifestation of competing interactions whose behavior is critically modified by defects and becomes even more complex when topological constraints are involved. In particular, the investigation of skyrmions and skyrmion lattices offers insight into fundamental processes of topological-charge creation and annihilation upon changing the magnetic state. Nonetheless, the exact physical mechanisms behind these phase transitions remain unresolved. Here, we show numerically that it is possible to collectively reverse the polarity of a skyrmion lattice in a field-induced first-order phase transition via a transient antiskyrmion-lattice state. We thus propose a new type of phase transformation where a skyrmion lattice inverts to another one due to topological constraints. In the presence of even a single defect, the process becomes a second-order phase transition with gradual topological-charge melting. This radical change in the system’s behavior from a first-order to a second-order phase transition demonstrates that defects in real materials could prevent us from observing collective topological phenomena. We have systematically compared ultra-thin films with isotropic and anisotropic Dzyaloshinskii-Moriya interactions (DMIs), and demonstrated a nearly identical behavior for such technologically relevant interfacial systems.
Deciphering the immune microenvironment of a tissue by digital imaging and cognition network
Authors: Lopès A. , Cassé Al H. , Billard E. , Boulcourt-Sambou E. , Roche G. , Larois C. , Barnich N. , Naimi S. , Bonnet M. , Dumas B.
Published: November 2018

Evidence has highlighted the importance of immune cells in various gut disorders. Both the quantification and localization of these cells are essential to the understanding of the complex mechanisms implicated in these pathologies. Even if quantification can be assessed (e.g., by flow cytometry), simultaneous cell localization and quantification of whole tissues remains technically challenging. Here, we describe the use of a computer learning-based algorithm created in the Tissue Studio interface that allows for a semi-automated, robust and rapid quantitative analysis of immunofluorescence staining on whole colon sections according to their distribution in different tissue areas. Indeed, this algorithm was validated to characterize gut immune microenvironment. Its application to the preclinical colon cancer APCMin/+ mouse model is illustrated by the simultaneous counting of total leucocytes and T cell subpopulations, in the colonic mucosa, lymphoid follicles and tumors. Moreover, we quantify T cells in lymphoid follicles for which quantification is not possible with classical methods. Thus, this algorithm is a new and robust preclinical research tool, for investigating immune contexture exemplified by T cells but it is also applicable to other immune cells such as other myeloid and lymphoid populations or other cellular phenomenon along mouse gut.
Comparison of linear frequency and amplitude modulation for intraneural sensory feedback in bidirectional hand prostheses
Authors: Valle G. , Petrini F. M. , Strauss I. , Iberite F. , D’Anna E. , Granata G. , Controzzi M. , Cipriani C. , Stieglitz T. , Rossini P. M. , Mazzoni A. , Raspopovic S. , Micera S.
Published: November 2018

Recent studies have shown that direct nerve stimulation can be used to provide sensory feedback to hand amputees. The intensity of the elicited sensations can be modulated using the amplitude or frequency of the injected stimuli. However, a comprehensive comparison of the effects of these two encoding strategies on the amputees’ ability to control a prosthesis has not been performed. In this paper, we assessed the performance of two trans-radial amputees controlling a myoelectric hand prosthesis while receiving grip force sensory feedback encoded using either linear modulation of amplitude (LAM) or linear modulation of frequency (LFM) of direct nerve stimulation (namely, bidirectional prostheses). Both subjects achieved similar and significantly above-chance performance when they were asked to exploit LAM or LFM in different tasks. The feedbacks allowed them to discriminate, during manipulation through the robotic hand, objects of different compliances and shapes or different placements on the prosthesis. Similar high performances were obtained when they were asked to apply different levels of force in a random order on a dynamometer using LAM or LFM. In contrast, only the LAM strategy allowed the subjects to continuously modulate the grip pressure on the dynamometer. Furthermore, when long-lasting trains of stimulation were delivered, LFM strategy generated a very fast adaptation phenomenon in the subjects, which caused them to stop perceiving the restored sensations. Both encoding approaches were perceived as very different from the touch feelings of the healthy limb (natural). These results suggest that the choice of specific sensory feedback encodings can have an effect on user performance while grasping. In addition, our results invite the development of new approaches to provide more natural sensory feelings to the users, which could be addressed by a more biomimetic strategy in the future.
Hepatitis A virus infections, immunisations and demographic determinants in children and adolescents, Germany
Authors: Michaelis Kai , Poethko-Müller Christina , Kuhnert Ronny , Stark Klaus , Faber Mirko
Published: November 2018

Hepatitis A is a vaccine-preventable disease with a global distribution. It predominantly occurs in regions with inadequate living conditions, but also affects populations in industrialised countries. Children are frequently involved in the transmission of hepatitis A virus (HAV) and thus play a central role in the epidemiology of hepatitis A. Here, we investigated HAV infections, immunisations, and associated demographic determinants in a nationwide, population-based, cross-sectional survey conducted in Germany from 2003–2006. Out of 17,640 children and adolescents, complete data sets (HAV serology, demographic information and vaccination card) were available for 12,249 (69%), all aged 3–17 years. We found protective antibody levels (>=20 IU/L) in 1,755 (14%) individuals, 1,395 (11%) were vaccinated against hepatitis A, 360 (3%) individuals were HAV seropositive without prior hepatitis A vaccination, thus indicating a previous HAV infection. Antibody prevalence (attributable to vaccination or infection) increased significantly with age. Multivariate logistic regression revealed that predominantly children and adolescents with migration background–even if they were born in Germany–are affected by HAV infections. Our results provide a rationale to emphasise existing vaccination recommendations and, moreover, to consider additional groups with a higher risk of infection for targeted vaccination, especially children with a migration background.
Magnetic field driven complex phase diagram of antiferromagnetic heavy-fermion superconductor Ce3PtIn11
Authors: Das Debarchan , Gnida Daniel , Bochenek Łukasz , Rudenko Andriy , Daszkiewicz Marek , Kaczorowski Dariusz
Published: November 2018

We present the results of our comprehensive investigation on the antiferromagnetic heavy-fermion superconductor Ce3PtIn11 carried out by means of electrical transport, heat capacity and ac magnetic susceptibility measurements, performed on single-crystalline specimens down to 50 mK in external magnetic fields up to 9 T. Our experimental results elucidate a complex magnetic field – temperature phase diagram which contains both first- and second-order field-induced magnetic transitions and highlights the emergence of field stabilized phases. Remarkably, a prominent metamagnetic transition was found to occur at low temperatures and strong magnetic fields. In turn, the results obtained in the superconducting phase of Ce3PtIn11 corroborate an unconventional nature of Cooper pairs formed by heavy quasiparticles. The compound is an almost unique example of a heavy fermion system in which superconductivity may coexist microscopically with magnetically ordered state.
Spin-torque devices with hard axis initialization as Stochastic Binary Neurons
Authors: Ostwal Vaibhav , Debashis Punyashloka , Faria Rafatul , Chen Zhihong , Appenzeller Joerg
Published: November 2018

Employing the probabilistic nature of unstable nano-magnet switching has recently emerged as a path towards unconventional computational systems such as neuromorphic or Bayesian networks. In this letter, we demonstrate proof-of-concept stochastic binary operation using hard axis initialization of nano-magnets and control of their output state probability (activation function) by means of input currents. Our method provides a natural path towards addition of weighted inputs from various sources, mimicking the integration function of neurons. In our experiment, spin orbit torque (SOT) is employed to “drive” nano-magnets with perpendicular magnetic anisotropy (PMA) -to their metastable state, i.e. in-plane hard axis. Next, the probability of relaxing into one magnetization state (+mi) or the other (−mi) is controlled using an Oersted field generated by an electrically isolated current loop, which acts as a “charge” input to the device. The final state of the magnet is read out by the anomalous Hall effect (AHE), demonstrating that the magnetization can be probabilistically manipulated and output through charge currents, closing the loop from charge-to-spin and spin-to-charge conversion. Based on these building blocks, a two-node directed network is successfully demonstrated where the status of the second node is determined by the probabilistic output of the previous node and a weighted connection between them. We have also studied the effects of various magnetic properties, such as magnet size and anisotropic field on the stochastic operation of individual devices through Monte Carlo simulations of Landau Lifshitz Gilbert (LLG) equation. The three-terminal stochastic devices demonstrated here are a critical step towards building energy efficient spin based neural networks and show the potential for a new application space.
Exploring representations of human grasping in neural, muscle and kinematic signals
Authors: Sburlea Andreea I. , Müller-Putz Gernot R.
Published: November 2018

Movement covariates, such as electromyographic or kinematic activity, have been proposed as candidates for the neural representation of hand control. However, it remains unclear how these movement covariates are reflected in electroencephalographic (EEG) activity during different stages of grasping movements. In this exploratory study, we simultaneously acquired EEG, kinematic and electromyographic recordings of human subjects performing 33 types of grasps, yielding the largest such dataset to date. We observed that EEG activity reflected different movement covariates in different stages of grasping. During the pre-shaping stage, centro-parietal EEG in the lower beta frequency band reflected the object’s shape and size, whereas during the finalization and holding stages, contralateral parietal EEG in the mu frequency band reflected muscle activity. These findings contribute to the understanding of the temporal organization of neural grasping patterns, and could inform the design of noninvasive neuroprosthetics and brain-computer interfaces with more natural control.