bluuebunny/crossref_metadata_2025 huggingface dataset:
Validation of etching model of polypropylene layers exposed to argon plasmas
Authors: Corbella Carles , Pranda Adam , Portal Sabine , de los Arcos Teresa , Grundmeier Guido , Oehrlein Gottlieb S. , von Keudell Achim
Published: March 2019

Thin layers of polypropylene (PP) have been treated by argon low‐temperature plasmas in an inductively coupled plasma setup. The etched thickness of PP was monitored in situ by means of single‐wavelength ellipsometry. The ellipsometric model of the polymer surface exposed to plasma consists of a UV‐modified layer, a dense amorphous carbon layer because of ion bombardment, and an effective medium approximation layer, which accounts for moderate surface roughness. The etching behavior has been compared to a model based on argon ion beam irradiation experiments. In this approach, surface processes are described in terms of etching yields and crosslinking probabilities as a function of incident fluxes and energies of Ar ions and UV photons. The ion beam model fits well with the plasma etching results.
Intermittent hypoxia in preterm infants: Measurement using the desaturation index
Authors: Wellington Grace , Campbell Angela , Elder Dawn
Published: March 2019

Objective

The aims of this study were to: (i) Determine in preterm infants at neonatal discharge the prevalence of intermittent hypoxia (IH), as measured by the oxygen desaturation index (DSI) recorded by pulse oximetry and (ii) Determine the change in values for very preterm infants at 1‐month post discharge.

Methods

Preterm infants were recruited from the Wellington regional neonatal intensive care unit (NICU) and 24‐h pulse oximetry recordings performed immediately before discharge. Infants born <32 weeks gestational age (GA) had repeat oximetry 1‐month post discharge. Oxygenation measures included the 3% and 4% desaturation (DSI 3%, DSI 4%) indices.

Results

At discharge from the neonatal unit the median and interquartile range (IQR) for DSI 4% was 51 (31‐74) events per hour with normal mean SpO2 (median of 97.9% [97.2‐98.8 IQR]). Episodes of IH 1 month post discharge decreased with improvements of between 42% and 57% seen for the three DSI measures. Infants <32 weeks GA had higher median DSI 3 and 4% values at discharge but differences when compared with late preterm infants were not significant.

Conclusions

Preterm infants have frequent episodes of IH as measured by the 3% and 4% DSI when deemed otherwise ready for discharge home. Further research in a larger cohort of very preterm infants and also in term infants is needed to determine the significance of this finding.
Routing algorithm design of satellite network architecture based on SDN and ICN
Authors: Liu Zhiguo , Zhu Jie , Zhang Jiangmei , Liu Qingli
Published: March 2019

In view of the problems of low routing efficiency, complex control process, and difficult network management in big data environment in the traditional integrated space‐terrestrial network, in the paper, we propose a satellite network architecture called software‐defined information centric satellite networking (SDICSN) based on software‐defined networking (SDN) and information‐centric networking (ICN), and we design a virtual node matrix routing algorithm (VNMR) under the SDICSN architecture. The SDICSN architecture realizes the flexibility of network management and business deployment through the features of the separation of forwarding and controlling by the SDN architecture and improves the response speed of requests in the network by the centric of “content” as the ICN idea. According to the periodicity and predictability of the satellite network, the VNMR algorithm obtains the routing matrix through the relative orientation of the source and destination nodes, thus reducing the spatial complexity of the input matrix of the Dijkstra algorithm and then reducing the time complexity of the routing algorithm. For forwarding information base (FIB), the mechanism of combination of event driven and polling can be quickly updated in real time. Finally, the advantages of the SDICSN architecture in routing efficiency, request delay, and request aggregation are verified by simulation.
Real‐Time Mapping of Ultratrace Singlet Oxygen in Rat during Acute and Chronic Inflammations via a Chemiluminescent Nanosensor
Authors: Zhang Shenghai , Cui Hongbo , Gu Min , Zhao Na , Cheng Mengqi , Lv Jiagen
Published: March 2019

Sensing nonradiation‐induced singlet oxygen (1O2) in whole‐animal is deemed as one of the most challenging tasks in noninvasive techniques due to the µs level lifetime of 1O2 and quenching by numerous reductants in tissues. Here a distinct chemiluminescent (CL) nanosensor (NTPE‐PH) that boasts ultrahigh concentrated CL units in one nanoparticle is reported. Taking advantage of the intramolecular energy transfer mechanism that promises high energy transfer efficiency and the aggregation‐induced emission behavior that guarantees high CL amplification, the NTPE‐PH sensor is sensitive to a nm level 1O2. Experiments demonstrate that the NTPE‐PH yields a highly selective CL response toward 1O2 among common reactive oxygen species. With proved low cytotoxicity and good animal compatibility, real‐time mapping of ultratrace 1O2 in whole‐animal during acute and chronic inflammations is first achieved. It is anticipated that the NTPE‐PH sensor can be a useful tool for monitoring 1O2 variation during immune response and pathological processes corresponding to different stimuli, even with drug treatment included.
New Templated Ostwald Ripening Process of Mesostructured FeOOH for Third‐Harmonic Generation Bioimaging
Authors: Lee Chien‐Wei , Wu Pei‐Chun , Hsu I‐Ling , Liu Tzu‐Ming , Chong Wai‐How , Wu Cheng‐Ham , Hsieh Tsung‐Yuan , Guo Lun‐Zhang , Tsao Yu , Wu Po‐Ting , Yu Jiashing , Tsai Pei‐Jane , Huang Huei‐Sheng , Chuang Yu‐Chun , Huang Chih‐Chia
Published: March 2019

Emerging advances in iron oxide nanoparticles exploit their high magnetization for various applications, such as bioseparation, hyperthermia, and magnetic resonance imaging. In contrast to their excellent magnetic performance, the harmonic generation and luminescence properties of iron oxide nanoparticles have not been thoroughly explored, thus limiting their development as a tool in photomedicine. In this work, a seed/growth‐inspired synthesis is developed combined with primary mineralization and a ligand‐assisted secondary growth strategy to prepare mesostructured α‐FeOOH nanorods (NRs). The sub‐wavelength heterogeneity of the refractive index leads to enhanced third‐harmonic generation (THG) signals under near‐infrared excited wavelengths at 1230 nm. The as‐prepared NRs exhibit an 11‐fold stronger THG intensity compared to bare α‐FeOOH NRs. Using these unique nonlinear optical properties, it is demonstrated that mesostructured α‐FeOOH NRs can serve as biocompatible and nonbleaching contrast agents in THG microscopy for long‐term labeling of cells as well as in angiography in vivo by modifying lectin to enhance the binding efficiency to the glycocalyx layers on the wall of blood vessels. These results provide a new insight into Fe‐based nanoplatforms capable of emitting coherent light as molecular probes in optical microscopy, thus establishing a complementary microscopic imaging method for macroscopic magnetic imaging systems.
Maintenance process modeling and dynamic estimations based on Bayesian networks and association rules
Authors: Chatzimparmpas Angelos , Bibi Stamatia
Published: March 2019

Managing the maintenance process and estimating accurately the effort and duration required for a new release is considered to be a crucial task as it affects successful software project survival and progress over time. In this study, we propose the combination of two well‐known machine learning (ML) techniques, Bayesian networks (BNs), and association rules (ARs) for modeling the maintenance process by identifying the relationships among the internal and external quality metrics related to a particular project release to both the maintainability of the project and the maintenance process indicators (ie, effort and duration). We also exploit Bayesian inference, to test the effect of certain changes in internal and external project factors to the maintainability of a project. We evaluate our approach through a case study on 957 releases of five open source JavaScript applications. The results show that the maintainability of a release, the changes observed between subsequent releases, and the time required between two releases can be accurately predicted from size, complexity, and activity metrics. The proposed combined approach achieves higher accuracy when evaluated against the BN model accuracy.
Stabilization of Short Oligonucleotides in the Prebiotic Mix: The Potential Role of Amino Alcohols
Authors: Pino Samanta , Di Mauro Ernesto , Costanzo Giovanna , Saladino Raffaele , Šedo Ondrej , Zdráhal Zbyněk , Šponer Jiří , Šponer Judit E.
Published: March 2019

Alkylation of RNA oligonucleotides by the amino alcohols 2‐amino‐2‐hydroxymethyl‐propane‐1,3‐diol (commonly known as Tris‐base) and 2‐amino‐2‐methyl‐1‐propanol has been observed in strongly acidic environments. The reaction occurs according to a carbocationic mechanism and is time‐, temperature‐, concentration‐ and, strictly, pH‐dependent. Our results suggest that amino alcohols present in the prebiotic mix could not only alter the chemical composition of the oligonucleotides formed on dry land under hydrothermal conditions, but, more importantly, they could protect the first informational polymers from degradation.
Added distance, entry mode choice, and the moderating effect of experience: The case of British MNEs in emerging markets
Authors: Batsakis Georgios , Singh Satwinder
Published: March 2019

Distance has been viewed as a crucial determinant of the internationalization strategy of firms. Nonetheless, in recent years, there has been considerable debate with regards to, first, the type of distance considered most important when it comes to explaining the internationalization strategy of firms, and, second, how distance should be measured. In our study, we argue that a developed market multinational enterprise (DMNE)’s decision regarding the mode of entry into an emerging market (EM) will be affected by the geographic and administrative distance between the locations in which the MNE has previously held operations. Drawing our arguments on transaction costs economics (TCE) and Internalization Theory, we propose that, for low and high geographic and administrative distance, DMNEs will opt to enter EMs via a wholly owned subsidiary, while for moderate levels of distance via a joint venture. Furthermore, we argue that DMNEs’ previous international experience in EMs will have a positive effect on the suggested U‐shaped relationship, alleviating the negative effects associated with the coordination and knowledge dissipation costs incurred as a result of the level of distance. Our study contributes to existing literature both theoretically—notably via the examination of under‐researched facets of distance on entry mode choice—and also methodologically—through the adoption of a novel methodological approach in measuring distance. We test our hypotheses against a data set comprising 316 entries of FTSE 250 British MNEs in 39 EMs spanning the period 1971–2010.
Massive scattering amplitudes in six dimensions
Authors: Jha Rishabh , Krishnan Chethan , Pavan Kumar K. V.
Published: March 2019

Abstract

We show that a natural spinor-helicity formalism that can describe massive scattering amplitudes exists in D = 6 dimensions. This is arranged by having helicity spinors carry an index in the Dirac spinor 4 of the massive little group, SO(5) ∼ Sp(4). In the high energy limit, two separate kinds of massless helicity spinors emerge as required for consistency with arXiv:0902.0981, with indices in the two SU(2)’s of the massless little group SO(4). The tensors of 4 lead to particles with arbitrary spin, and using these and demanding consistent factorization, we can fix 3− and 4-point tree amplitudes of arbitrary masses and spins: we provide examples. We discuss the high energy limit of scattering amplitudes and the Higgs mechanism in this language, and make some preliminary observations about massive BCFW recursion.
Use of Magnetic Induction to Activate a “Touchless” Shape Memory Alloy Implantable Penile Prosthesis
Authors: Le Brian V. , McVary Kevin T. , McKenna Kevin , Colombo Alberto
Published: March 2019

Introduction

We describe a novel physiologic penile prosthesis that uses shape memory alloy properties to mimic the transition between a flaccid and erect penis using magnetic induction instead of hydraulic pressure.

Aim

To evaluate the parameters of magnetic induction to activate a shape memory alloy implantable penile prosthesis.

Methods

We prototyped an implantable penile prosthesis cylinder using temperature-tuned nickel titanium alloy tubes laser cut to specifications.

The device was then tested implanted in an animal tissue model and in cadaveric tissue. Testing consisted of placing the device deactivated in its more malleable and compressed state, then activating it using an external inducer wand while measuring temperature changes that occur on the surface of the device, within the tissue, and at the skin surface.

Main Outcome Measures

Our main outcome measures were the efficiency of activation and thermal safety of this approach.

Results

Using a handheld magnetic inductor, we were able to successfully activate the SMA penile prosthesis with no direct contact under 45 seconds. This handheld wand produced a magnetic field that penetrated tissue and caused the appropriate phase change within the prosthesis. Tissue temperature (middle and surface probes) in the animal tissue model increased only a few degrees Celsius during the activation process, and never exceeded 28 degrees Celsius from a baseline at room temperature ∼ 25 degrees Celsius. We encountered similar results without a notable change in tissue temperature in the cadaveric tests. The fully activated device resisted buckling forces of 2.66 kgf ± 0.045.

Clinical Implications

This non-hydraulic shape memory prosthesis obviates the needs for reservoirs and pumps, and the wand-based interaction with the device may be easier to use.

Strength & Limitations

This technology represents a fundamental departure from the hydraulic-based penile prosthesis and has comparable mechanical properties as current-marked devices. It appears to show thermal safety in controlled environments, however real-world use would need further studies. Further optimization of prototypes needs to be done prior to human clinical trials.

Conclusion

A shape memory penile prosthesis is a promising alternative to hydraulic-based penile prostheses and can be activated safely and efficiently using magnetic induction in our models of the human penis.
Hegel on Addiction
Authors: Deligiorgi Katerina
Published: March 2019

The aim of this paper is to show how certain distinctive elements of Hegel's theory of action can provide a fresh philosophical perspective on the phenomenon of addiction. What motivates the turn to Hegel is a set of puzzles that arise out of contemporary medical and philosophical discussions of addiction. Starting with questions concerning ongoing attempts to define addiction, the paper examines the resources needed for addiction to be classed as a disorder, as it commonly is. Provisionally settling with the notion of akrasia, the paper turns to Hegel for a theory of agency that fills in the gaps of the account of akrasia used in the contemporary literature on addiction and helps resolve the puzzles that occasioned the paper.
Emotional contagion in children with autism spectrum disorder varies with stimulus familiarity and task instructions
Authors: Helt Molly S. , Fein Deborah A. , Vargas Jacob E.
Published: March 2019

Although deficits in cognitive empathy are well established in individuals with autism spectrum disorder (ASD), the literature on emotional empathy, or emotional contagion, in individuals with ASD is sparse and contradictory. The authors tested susceptibility to contagious yawning and laughter in children with ASD (n= 60) and typically developing (TD) children (n= 60), ages 5–17 years, under various conditions, to elucidate factors that may affect emotional contagion in these populations. Although TD children showed equal amounts of emotional contagion across conditions, children with ASD were highly influenced by the familiarity of the target stimulus, as well as task instructions that encourage eye gaze to target. More specifically, children with ASD exhibited less contagious yawning and laughter than their TD peers except when their attention was explicitly directed to the eyes or (and even more so) when their parents served as the stimulus targets. The authors explore the implications of these findings for theories about the mechanisms underlying empathic deficits in ASD as well as the clinical implications of having parents involved in treatment.
People will enter the downtown – the postwar ruralisation of the proletarian city of Łódź (1945–55)
Authors: Zysiak Agata
Published: March 2019

This article deals with the postwar confrontation of the rural and the urban in Poland. It sheds light on a time of mass migration to the cities and the postwar reconstruction in Central Europe, heading towards state-socialism, and focuses on official discourses concerning peasants as new social and political subjects and the intelligentsia’s response to rural newcomers. A testing ground for these processes was the Polish city of Łódź, the biggest textile industrial centre.

These processes became the subject of both journalistic and academic inquiries framed by political efforts to reshape the ‘social imaginary’ (Taylor) through the state’s ‘socialist modernization’. Along with the scale of migration, there was another unprecedented aspect: peasants were becoming citizens, recognised political subjects, later even as privileged representatives of the People’s Republic. The postwar press and political speeches encouraged them to become a part of the modernisation project. Almost immediately, counter-narratives followed and lamented the newcomers’ ‘improper’ uses of the city. The term ‘ruralisation of the city’ was coined to describe the misuses of urban spaces, a moral decline and even the negative influence of peasants on the urban working class.
The Mechanisms of Social Norms’ Influence on Consumer Decision Making
Authors: Melnyk Vladimir , van Herpen Erica , Jak Suzanne , van Trijp Hans C. M.
Published: March 2019

Abstract. In the past decades, marketing practitioners have embraced social norms as a powerful instrument of influencing consumers’ behavior. An important distinction has been made between descriptive norms (what most others do) and injunctive norms (what others approve of), and this meta-analysis across 297 studies examines the effects of these types of social norms on consumer decision-making processes. We argue that descriptive norms directly influence behavior, and consequently that their effect on behavior should be stronger than that of injunctive norms. Injunctive norms, by contrast, should be more strongly related to intentions than descriptive norms. Results of the meta-analysis support these predictions, and furthermore provide new insights into the moderating effects of aspects of the norm (specificity of the norm, norm source) and of the target person (gender, age).
Impaired Interparental Relationships in Families of Children With	Attention-Deficit/Hyperactivity Disorder (ADHD)
Authors: Weyers Lena , Zemp Martina , Alpers Georg W.
Published: March 2019

Abstract. Research on attention-deficit/hyperactivity disorder (ADHD) in children and adolescents has traditionally focused on the genetic and neurobiological aspects of the disorder, but the role of family relationships has been much less systematically examined. There is growing evidence that the quality of interparental relationships and a child’s ADHD symptoms are reciprocally related. Because the literature appears to be inconsistent, this meta-analysis aims to summarize previous research and assess whether there are robust differences in the quality of interparental relationships between parents of children with ADHD and parents of healthy children. This meta-analysis of 15 studies with 43 effect sizes revealed a small but significant difference ( d = .24), which indicates that parents of a child with ADHD report poorer relationship quality than parents of healthy children. This effect was moderated by the child’s age and did not depend on whether the child had a comorbid oppositional defiant disorder (ODD) or conduct disorder (CD). The causality of this relationship has yet to be determined.
Accurate Measurement of Small Features in X‐Ray CT Data Volumes, Demonstrated Using Gold Grains
Authors: Ketcham R. A. , Mote A. S.
Published: March 2019

We present a method for measuring small, discrete features near the resolution limit of X‐ray computed tomography (CT) data volumes with the aim of providing consistent answers across instruments and data resolutions. The appearances of small features are impacted by the partial volume effect and blurring due to the data point‐spread function, and we call our approach the partial‐volume and blurring (PVB) method. Features are segmented to encompass their total attenuation signal, which is then converted to a volume, in turn allowing a subset of voxels to be used to measure shape and orientation. We demonstrate the method on a set of gold grains, scanned with two instruments at a range of resolutions and with various surrounding media. We recover volume accurately over a factor of 27 range in grain volume and factor of 5 range in data resolution, successfully characterizing particles as small as 5.4 voxels in true volume. Shape metrics are affected variably by resolution effects and are more reliable when based on image‐based caliper measurements than perimeter length or surface area. Orientations are reproducible when maximum or minimum axis lengths are sufficiently different from the intermediate axis. Calibration requires end‐member CT numbers for the materials of interest, which we obtained empirically; we describe a first‐principles calculation and discuss its challenges. The PVB method is accurate, reproducible, resolution invariant, and objective, all important improvements over any method based on global thresholds.
Prediction of Northern Hemisphere Regional Surface Temperatures Using Stratospheric Ozone Information
Authors: Stone Kane A. , Solomon Susan , Kinnison Douglas E. , Baggett Cory F. , Barnes Elizabeth A.
Published: March 2019

Correlations between springtime stratospheric ozone extremes and subsequent surface temperatures have been previously reported for both models and observations at particular locations in the Northern Hemisphere. Here we quantify for the first time the potential use of ozone information for Northern Hemisphere seasonal forecasts, using observations and a nine‐member chemistry climate model ensemble. The ensemble composite correlations between March total column ozone (TCO) and April surface temperatures display a similar structure to observations, but with slightly lower correlation magnitudes. This is likely due to the larger number of cases smoothing out sampling error in the pattern, which is visible in the difference between correlations calculated from individual ensemble members. Using a linear regression model with March TCO as the predictor, predictions of the following April surface temperatures in regions that show large correlations are possible up to 4 years following the regression model end date in individual ensemble members, and up to 6 years in observations. We create an empirical forecast model to predict the sign of the observed as well as the modeled surface temperature anomalies using March TCO. Through a leave‐three‐years‐out cross‐validation method, we show that March TCO can forecast the sign of the April surface temperature anomalies well in parts of Eurasia that show the lowest model internal variability.
Uncertainty in Assessing Temperature Impact on U.S. Maize Yield Under Global Warming: The Role of Compounding Precipitation Effect
Authors: Leng Guoyong
Published: March 2019

High temperature alone would lead to a well‐understood loss of crop yields, but the compounding effects by other global change factors are much less well understood and can either amplify or reduce temperature‐driven yield change. Analysis focusing on U.S. maize yield shows that the concurrent changes in precipitation have nonnegligible influence on temperature‐yield relations. For the country as a whole, ~27% of the observed strength of temperature‐yield relation relates to the compounding precipitation effects. Further analysis shows that precipitation exerted the compounding effects mainly through its direct influence on yields rather than indirectly from its feedback to temperature. Under 2 and 1.5°C global warming, maize yield for the country as a whole is projected to decrease by ‐13.53 to ‐14.37% and ‐9.02 to ‐9.29%, respectively, with the magnitude of change depending on the climate model. Around 30% of the benefit by constraining global warming to 1.5°C would be contributed by the compounding precipitation effects, pointing to the important role of precipitation in regulating the impacts of temperature rise on yields. The results can greatly improve our understanding and interpretation of the important but uncertain temperature‐yield relations.
Spatioseasonal Variations of Atmospheric Ammonia Concentrations Over the United States: Comprehensive Model‐Observation Comparison
Authors: Nair Arshad Arjunan , Yu Fangqun , Luo Gan
Published: March 2019

Atmospheric ammonia plays an important role in a number of environmental issues, including new particle formation and aerosol indirect radiative forcing. Over the United States, atmospheric ammonia has seen an increasing trend due in most part to the declining SO2 and NOx emissions. We conduct the first comprehensive assessment of multiyear Goddard Earth Observing System (GEOS)‐Chem simulated ammonia concentration ([NH3]) over conterminous United States along with surface observations from all 90 National Atmospheric Deposition Program Ammonia Monitoring Network (AMoN) sites that have at least 2 years of continuous measurements. Model‐simulated [NH3] is along empirically expected lines with regard to temporal trends, seasonal variations, and spatial distribution. GEOS‐Chem‐simulated [NH3], compared to AMoN observed values, has weighted average correlation (τ) of 0.50 ± 0.15 and mean fractional bias (MFB) of −8.8 ± 56%. Most sites (63 out of 90) have −60% < MFB < +60%. The deviations from observed values vary spatially and seasonally, and there is significant wintertime underestimation (−44 ± 58%) across most of conterminous United States (except the Pacific states). The largest positive deviations occur in the Pacific states (101 ± 46%) and the largest negative deviations in the Southern Plain states (−73 ± 39%) and the Mountain states (−73 ± 84%), both in the winter months. Over the Great Plains region, GEOS‐Chem simulated [NH3] shows a much stronger dependence to emissions than AMoN observed [NH3], indicating scope for improved representation of emissions for the region. Over Southeast United States, there appears to be the strong effect of the changing emissions of SO2 and NOx in both modeled and observed [NH3].
Wave‐Driven Sediment Resuspension Within a Model Eelgrass Meadow
Authors: Zhang Yinghao , Nepf Heidi
Published: March 2019

Wave velocity and suspended sediment concentration were measured over a sand bed with and without a model eelgrass meadow. The model meadow was geometrically and dynamically similar to the marine eelgrass Zostera marina. Meadows were constructed with three stem densities: 280, 600, and 820 stems/m2. Ripples formed within the meadow only when the spacing between stem rows was larger than the wave excursion. When ripples formed, the ripple geometry was the same as that observed for bare bed. When ripples were present, the near‐bed turbulent kinetic energy (TKE) was dominated by the ripple‐generated turbulence, and both the near‐bed TKE and averaged suspended sediment concentration were similar across all meadow densities and bare bed at the same wave velocity. When ripples were absent, the near‐bed TKE was dominated by the stem‐generated turbulence, and the averaged suspended sediment concentration was reduced, compared to cases with ripples but at the same wave velocity. For conditions with and without a model meadow, the sediment diffusivity inferred from vertical profiles of suspended sediment concentration increased linearly with distance from the bed.
Rest in Peace, Spirit and Opportunity
Authors: Anderson Ryan
Published: March 2019

A scientist on the rover team offers a remembrance of two intrepid explorers.
Sea Ice Meltwater and Circumpolar Deep Water Drive Contrasting Productivity in Three Antarctic Polynyas
Authors: Moreau S. , Lannuzel D. , Janssens J. , Arroyo M. C. , Corkill M. , Cougnon E. , Genovese C. , Legresy B. , Lenton A. , Puigcorbé V. , Ratnarajah L. , Rintoul S. , Roca‐Martí M. , Rosenberg M. , Shadwick E. H. , Silvano A. , Strutton P. G. , Tilbrook B.
Published: March 2019

In the Southern Ocean, polynyas exhibit enhanced rates of primary productivity and represent large seasonal sinks for atmospheric CO2. Three contrasting east Antarctic polynyas were visited in late December to early January 2017: the Dalton, Mertz, and Ninnis polynyas. In the Mertz and Ninnis polynyas, phytoplankton biomass (average of 322 and 354 mg chlorophyll a (Chl a)/m2, respectively) and net community production (5.3 and 4.6 mol C/m2, respectively) were approximately 3 times those measured in the Dalton polynya (average of 122 mg Chl a/m2 and 1.8 mol C/m2). Phytoplankton communities also differed between the polynyas. Diatoms were thriving in the Mertz and Ninnis polynyas but not in the Dalton polynya, where Phaeocystis antarctica dominated. These strong regional differences were explored using physiological, biological, and physical parameters. The most likely drivers of the observed higher productivity in the Mertz and Ninnis were the relatively shallow inflow of iron‐rich modified Circumpolar Deep Water onto the shelf as well as a very large sea ice meltwater contribution. The productivity contrast between the three polynyas could not be explained by (1) the input of glacial meltwater, (2) the presence of Ice Shelf Water, or (3) stratification of the mixed layer. Our results show that physical drivers regulate the productivity of polynyas, suggesting that the response of biological productivity and carbon export to future change will vary among polynyas.
Understanding Ice Cloud‐Precipitation Properties of Three Modes of Mesoscale Convective Systems During PECAN
Authors: Cui Wenjun , Dong Xiquan , Xi Baike , Fan Jiwen , Tian Jingjing , Wang Jingyu , McHardy Theodore M.
Published: March 2019

This study analyzes the precipitation and ice cloud microphysical features of three common modes of linear mesoscale convective systems during the Plains Elevated Convection at Night (PECAN) campaign. Three cases, one for each linear mesoscale convective system archetype (trailing stratiform, leading stratiform, and parallel stratiform precipitation), are selected. We focus primarily on analyzing ice cloud microphysical properties and precipitation rates (PRs) over the classified convective core (CC) and stratiform rain (SR) regions, as well as the two stratiform regions that developed behind (SR1) and ahead (SR2) of the convective line relative to the storm motion. In the three selected cases, the ice water path (IWP) and PR have strong correlations in the CC, but not in the SR. In terms of the temporal evolution of the mean IWPs and PRs, both CC and SR IWPs, as well as CC PRs, reach peaks quickly but take a longer time to dissipate than the increase period. For all the three cases, both SR1 and SR2 IWPs are 20–70% of their corresponding CC values in both the leading stratiform and parallel stratiform cases and up to 95% for the trailing stratiform case, while all of their PRs are only 7–25% of their CC values. These values suggest not only that the SR PRs may depend on IWPs but also that the microphysical properties of ice particles such as habit and size distribution may play an important role. Utilizing cloud‐resolving simulations of these systems may provide better understanding of the physical meanings behind the results in the future.
Hydrogen sulfide: a gaseous signaling molecule modulates tissue homeostasis: implications in ophthalmic diseases
Authors: Han Yuyi , Shang Qianwen , Yao Jin , Ji Yong
Published: March 2019

Hydrogen sulfide (H2S) serves as a gasotransmitter in the regulation of organ development and maintenance of homeostasis in tissues. Its abnormal levels are associated with multiple human diseases, such as neurodegenerative disease, myocardial injury, and ophthalmic diseases. Excessive exposure to H2S could lead to cellular toxicity, orchestrate pathological process, and increase the risk of various diseases. Interestingly, under physiological status, H2S plays a critical role in maintaining cellular physiology and limiting damages to tissues. In mammalian species, the generation of H2S is catalyzed by cystathionine beta-synthase (CBS), cystathionine gamma-lyase (CSE), 3-mercapto-methylthio pyruvate aminotransferase (3MST) and cysteine aminotransferase (CAT). These enzymes are found inside the mammalian eyeballs at different locations. Their aberrant expression and the accumulation of substrates and intermediates can change the level of H2S by orders of magnitude, causing abnormal structures or functions in the eyes. Detailed investigations have demonstrated that H2S donors’ administration could regulate intraocular pressure, protect retinal cells, inhibit oxidative stress and alleviate inflammation by modulating the function of intra or extracellular proteins in ocular tissues. Thus, several slow-releasing H2S donors have been shown to be promising drugs for treating multiple diseases. In this review, we discuss the biological function of H2S metabolism and its application in ophthalmic diseases.
Stacking angle-tunable photoluminescence from interlayer exciton states in twisted bilayer graphene
Authors: Patel Hiral , Huang Lujie , Kim Cheol-Joo , Park Jiwoong , Graham Matt W.
Published: March 2019

Twisted bilayer graphene (tBLG) is a metallic material with two degenerate van Hove singularity transitions that can rehybridize to form interlayer exciton states. Here we report photoluminescence (PL) emission from tBLG after resonant 2-photon excitation, which tunes with the interlayer stacking angle, θ. We spatially image individual tBLG domains at room-temperature and show a five-fold resonant PL-enhancement over the background hot-electron emission. Prior theory predicts that interlayer orbitals mix to create 2-photon-accessible strongly-bound (~0.7 eV) exciton and continuum-edge states, which we observe as two spectral peaks in both PL excitation and excited-state absorption spectra. This peak splitting provides independent estimates of the exciton binding energy which scales from 0.5–0.7 eV with θ = 7.5° to 16.5°. A predicted vanishing exciton-continuum coupling strength helps explain both the weak resonant PL and the slower 1 ps−1 exciton relaxation rate observed. This hybrid metal-exciton behavior electron thermalization and PL emission are tunable with stacking angle for potential enhancements in optoelectronic and fast-photosensing graphene-based applications.
Ventral tegmental area astrocytes orchestrate avoidance and approach behavior
Authors: Gomez J. A. , Perkins J. M. , Beaudoin G. M. , Cook N. B. , Quraishi S. A. , Szoeke E. A. , Thangamani K. , Tschumi C. W. , Wanat M. J. , Maroof A. M. , Beckstead M. J. , Rosenberg P. A. , Paladini C. A.
Published: March 2019

The ventral tegmental area (VTA) is a heterogeneous midbrain structure, containing neurons and astrocytes, that coordinates behaviors by integrating activity from numerous afferents. Within neuron-astrocyte networks, astrocytes control signals from distinct afferents in a circuit-specific manner, but whether this capacity scales up to drive motivated behavior has been undetermined. Using genetic and optical dissection strategies we report that VTA astrocytes tune glutamatergic signaling selectively on local inhibitory neurons to drive a functional circuit for learned avoidance. In this circuit, astrocytes facilitate excitation of VTA GABA neurons to increase inhibition of dopamine neurons, eliciting real-time and learned avoidance behavior that is sufficient to impede expression of preference for reward. Loss of one glutamate transporter (GLT-1) from VTA astrocytes selectively blocks these avoidance behaviors and spares preference for reward. Thus, VTA astrocytes selectively regulate excitation of local GABA neurons to drive a distinct avoidance circuit that opposes approach behavior.
Human RAD51 paralogue SWSAP1 fosters RAD51 filament by regulating the anti-recombinase FIGNL1 AAA+ ATPase
Authors: Matsuzaki Kenichiro , Kondo Shizuka , Ishikawa Tatsuya , Shinohara Akira
Published: March 2019

RAD51 assembly on single-stranded (ss)DNAs is a crucial step in the homology-dependent repair of DNA damage for genomic stability. The formation of the RAD51 filament is promoted by various RAD51-interacting proteins including RAD51 paralogues. However, the mechanisms underlying the differential control of RAD51-filament dynamics by these factors remain largely unknown. Here, we report a role for the human RAD51 paralogue, SWSAP1, as a novel regulator of RAD51 assembly. Swsap1-deficient cells show defects in DNA damage-induced RAD51 assembly during both mitosis and meiosis. Defective RAD51 assembly in SWSAP1-depleted cells is suppressed by the depletion of FIGNL1, which binds to RAD51 as well as SWSAP1. Purified FIGNL1 promotes the dissociation of RAD51 from ssDNAs. The dismantling activity of FIGNL1 does not require its ATPase but depends on RAD51-binding. Purified SWSAP1 inhibits the RAD51-dismantling activity of FIGNL1. Taken together, our data suggest that SWSAP1 protects RAD51 filaments by antagonizing the anti-recombinase, FIGNL1.
Enhancing oxygen evolution efficiency of multiferroic oxides by spintronic and ferroelectric polarization regulation
Authors: Li Xiaoning , Liu Huan , Chen Zezhi , Wu Qingmei , Yu Zheyin , Yang Mengmeng , Wang Xiaolin , Cheng Zhenxiang , Fu Zhengping , Lu Yalin
Published: March 2019

Regulating the electronic structure of catalysts is the most efficient strategy yet, despite its limitations, to improve their oxygen evolution efficiency. Instead of only adjusting the electronic structure, here we utilize ferroelectric polarization to accelerate the oxygen evolution reaction as well. This is demonstrated on a multiferroic layered perovskite Bi5CoTi3O15 with in-situ grown BiCoO3. Thanks to the superimposed effects of electronic regulation and ferroelectric polarization, the as-prepared multiferroic electrocatalysts are more efficient than the benchmark IrO2 (with a final 320 mV overpotential at the current density of 10 mA cm−2 and a 34 mV dec−1 Tafel slope). This work not only demonstrates a low-cost and high-efficient OER electrocatalyst, but also provides a strategic design for multi-component electrocatalytic material systems by consideration of both spin and polarization degrees of freedom.
Rad52 prevents excessive replication fork reversal and protects from nascent strand degradation
Authors: Malacaria Eva , Pugliese Giusj Monia , Honda Masayoshi , Marabitti Veronica , Aiello Francesca Antonella , Spies Maria , Franchitto Annapaola , Pichierri Pietro
Published: March 2019

Stabilisation of stalled replication forks prevents excessive fork reversal and their pathological degradation, which can undermine genome integrity. Here we investigate a physiological role of RAD52 at stalled replication forks by using human cell models depleted of RAD52, a specific small-molecule inhibitor of the RAD52-ssDNA interaction, in vitro and single-molecule analyses. We demonstrate that RAD52 prevents excessive degradation of reversed replication forks by MRE11. Mechanistically, RAD52 binds to the stalled replication fork, promotes its occlusion and counteracts loading of SMARCAL1 in vitro and in vivo. Loss of the RAD52 function results in a slightly-defective replication restart, persistence of under-replicated regions and chromosome instability. Moreover, the RAD52-inhibited cells rely on RAD51 for completion of replication and viability upon replication arrest. Collectively, our data suggest an unexpected gatekeeper mechanism by which RAD52 limits excessive remodelling of stalled replication forks, thus indirectly assisting RAD51 and BRCA2 in protecting forks from unscheduled degradation and preventing genome instability.
Multiplex imaging relates quantal glutamate release to presynaptic Ca2+ homeostasis at multiple synapses in situ
Authors: Jensen Thomas P. , Zheng Kaiyu , Cole Nicholas , Marvin Jonathan S. , Looger Loren L. , Rusakov Dmitri A.
Published: March 2019

Information processing by brain circuits depends on Ca2+-dependent, stochastic release of the excitatory neurotransmitter glutamate. Whilst optical glutamate sensors have enabled detection of synaptic discharges, understanding presynaptic machinery requires simultaneous readout of glutamate release and nanomolar presynaptic Ca2+ in situ. Here, we find that the fluorescence lifetime of the red-shifted Ca2+ indicator Cal-590 is Ca2+-sensitive in the nanomolar range, and employ it in combination with green glutamate sensors to relate quantal neurotransmission to presynaptic Ca2+ kinetics. Multiplexed imaging of individual and multiple synapses in identified axonal circuits reveals that glutamate release efficacy, but not its short-term plasticity, varies with time-dependent fluctuations in presynaptic resting Ca2+ or spike-evoked Ca2+ entry. Within individual presynaptic boutons, we find no nanoscopic co-localisation of evoked presynaptic Ca2+ entry with the prevalent glutamate release site, suggesting loose coupling between the two. The approach enables a better understanding of release machinery at central synapses.
Ligand design strategies to increase stability of gadolinium-based magnetic resonance imaging contrast agents
Authors: Clough Thomas J. , Jiang Lijun , Wong Ka-Leung , Long Nicholas J.
Published: March 2019

Gadolinium(III) complexes have been widely utilised as magnetic resonance imaging (MRI) contrast agents for decades. In recent years however, concerns have developed about their toxicity, believed to derive from demetallation of the complexes in vivo, and the relatively large quantities of compound required for a successful scan. Recent efforts have sought to enhance the relaxivity of trivalent gadolinium complexes without sacrificing their stability. This review aims to examine the strategic design of ligands synthesised for this purpose, provide an overview of recent successes in gadolinium-based contrast agent development and assess the requirements for clinical translation.
The architecture of functional lateralisation and its relationship to callosal connectivity in the human brain
Authors: Karolis Vyacheslav R. , Corbetta Maurizio , Thiebaut de Schotten Michel
Published: March 2019

Functional lateralisation is a fundamental principle of the human brain. However, a comprehensive taxonomy of functional lateralisation and its organisation in the brain is missing. Here, we report the first complete map of functional hemispheric asymmetries in the human brain, reveal its low dimensional structure, and its relationship with structural inter-hemispheric connectivity. Our results suggest that the lateralisation of brain functions is distributed along four functional axes: symbolic communication, perception/action, emotion, and decision-making. The similarity between this finding and recent work on neurological symptoms give rise to new hypotheses on the mechanisms that support brain recovery after a brain lesion. We also report that cortical regions showing asymmetries in task-evoked activity have reduced connections with the opposite hemisphere. This latter result suggests that during evolution, brain size expansion led to functional lateralisation to avoid excessive conduction delays between the hemispheres.
Semi-solid prodrug nanoparticles for long-acting delivery of water-soluble antiretroviral drugs within combination HIV therapies
Authors: Hobson James J. , Al-khouja Amer , Curley Paul , Meyers David , Flexner Charles , Siccardi Marco , Owen Andrew , Meyers Caren Freel , Rannard Steve P.
Published: March 2019

The increasing global prevalence of human immunodeficiency virus (HIV) is estimated at 36.7 million people currently infected. Lifelong antiretroviral (ARV) drug combination dosing allows management as a chronic condition by suppressing circulating viral load to allow for a near-normal life; however, the daily burden of oral administration may lead to non-adherence and drug resistance development. Long-acting (LA) depot injections of nanomilled poorly water-soluble ARVs have shown highly promising clinical results with drug exposure largely maintained over months after a single injection. ARV oral combinations rely on water-soluble backbone drugs which are not compatible with nanomilling. Here, we evaluate a unique prodrug/nanoparticle formation strategy to facilitate semi-solid prodrug nanoparticles (SSPNs) of the highly water-soluble nucleoside reverse transcriptase inhibitor (NRTI) emtricitabine (FTC), and injectable aqueous nanodispersions; in vitro to in vivo extrapolation (IVIVE) modelling predicts sustained prodrug release, with activation in relevant biological environments, representing a first step towards complete injectable LA regimens containing NRTIs.
Coordination of capsule assembly and cell wall biosynthesis in Staphylococcus aureus
Authors: Rausch Marvin , Deisinger Julia P. , Ulm Hannah , Müller Anna , Li Wenjin , Hardt Patrick , Wang Xiaogang , Li Xue , Sylvester Marc , Engeser Marianne , Vollmer Waldemar , Müller Christa E. , Sahl Hans Georg , Lee Jean Claire , Schneider Tanja
Published: March 2019

The Gram-positive cell wall consists of peptidoglycan functionalized with anionic glycopolymers, such as wall teichoic acid and capsular polysaccharide (CP). How the different cell wall polymers are assembled in a coordinated fashion is not fully understood. Here, we reconstitute Staphylococcus aureus CP biosynthesis and elucidate its interplay with the cell wall biosynthetic machinery. We show that the CapAB tyrosine kinase complex controls multiple enzymatic checkpoints through reversible phosphorylation to modulate the consumption of essential precursors that are also used in peptidoglycan biosynthesis. In addition, the CapA1 activator protein interacts with and cleaves lipid-linked CP precursors, releasing the essential lipid carrier undecaprenyl-phosphate. We further provide biochemical evidence that the subsequent attachment of CP is achieved by LcpC, a member of the LytR-CpsA-Psr protein family, using the peptidoglycan precursor native lipid II as acceptor substrate. The Ser/Thr kinase PknB, which can sense cellular lipid II levels, negatively controls CP synthesis. Our work sheds light on the integration of CP biosynthesis into the multi-component Gram-positive cell wall.