bluuebunny/crossref_metadata_2025 huggingface dataset:
Little string theories on curved manifolds
Authors: Aharony Ofer , Evtikhiev Mikhail , Feldman Andrey
Published: October 2019

Abstract

In this paper, we study the 6d Little String Theory (LST) (the decoupled theory on the worldvolume of N NS5-branes) on curved manifolds, by using its holographic duality to Type II string theory in asymptotically linear dilaton backgrounds. We focus on backgrounds with a large number of Killing vectors (namely, products of maximally symmetric spaces), without requiring supersymmetry (we do not turn on any background fields except the metric). LST is non-local so it is not obvious which spaces it can be defined on; we show that holography implies that the theory cannot be put on negatively curved spaces, but only on spaces with zero or positive curvature. For example, one cannot put LST on a product of an anti-de Sitter space times another space, without turning on extra background fields. On spaces with positive curvature, such as S
6, ℝ2
× S
4, S
3
× S
3, etc., we typically find (for large N) dual holographic backgrounds which are weakly coupled and weakly curved everywhere, so that they can be well-described by Type II supergravity. In some cases more than one smooth solution exists for LST on the same space, and they all contribute to the partition function. We also study the thermodynamical properties of LST compactified on spheres, finding the leading correction to the Hagedorn behavior of the spectrum, which is different on curved space than on flat space. We discuss the holographic renormalization procedure, which must be implemented in order to get a finite free energy for the LST; we do not know how to implement it for general spaces, but we can (and we do) implement it for the theory compactified on S
4.
The holographic dual to supergravity instantons in AdS5× S5/ℤk
Authors: Katmadas S. , Ruggeri D. , Trigiante M. , Van Riet T.
Published: October 2019

Abstract

We investigate the holographic dual to supergravity instanton solutions in AdS5 × S5
/ ℤk, which are described entirely in terms of geodesics on the AdS moduli space. These instantons are expected to be holographically dual to instantons in an

$$ \mathcal{N} $$

N

= 2 necklace quiver gauge theory in four dimensions with k gauge nodes, at large N. For the supersymmetric instantons we find a precise match between the on-shell actions and the vevs of Tr[F
2] and Tr[F ∧ F ] computed on both sides of the duality. This correspondence requires an exact identification between the massless supergravity scalars and the dual gauge couplings which we give in detail. We also find a candidate for the supergravity dual of a quasi-instanton in the quiver theory, which is a non-supersymmetric extremal solution.
Evidence for natural attenuation of 1,4-dioxane in a glacial aquifer system
Authors: Jackson Leah E. , Lemke Lawrence D.
Published: October 2019

Although 1,4-dioxane is generally thought to be recalcitrant, recent studies suggest it may degrade in the subsurface under ideal conditions. A fuller understanding of natural attenuation processes affecting 1,4-dioxane is therefore needed to assess its potential for in situ bioremediation. This investigation employed multiple lines of evidence to evaluate attenuation of 1,4-dioxane at the Gelman Site beneath the city of Ann Arbor, Michigan, USA. Data from a network of groundwater monitoring wells were used to determine attenuation metrics at individual wells and at the scale of a prominent 1,4-dioxane plume. A series of plume maps and historical remediation data were used to calculate changes in aqueous phase mass storage, mass influx rates, and mass removal rates over a 12-year period (2005–2017). Individual point and plume-scale metrics indicate that attenuation may be occurring at rates too small to meaningfully contribute to remediation results at the site. Conversely, plume-scale mass balance calculations reveal a 1,4-dioxane storage surplus for the first 6 years, followed by a storage deficit during the remaining 6 years that cannot be explained by mass influx or removal estimates, respectively. Mass balance deficits observed in this aquifer system are attributable to biodegradation and/or unrecognized discharge to surface water and storm drain systems at rates similar to remedial pump-and-treat mass removal during 2011–2017.
Comparison of adsorption of selected antibiotics on the filters in continuous renal replacement therapy circuits: in vitro studies
Authors: Onichimowski Dariusz , Ziółkowski Hubert , Nosek Krzysztof , Jaroszewski Jerzy , Rypulak Elżbieta , Czuczwar Mirosław
Published: October 2019

The aim of this study was to assess the adsorption of selected antibiotics: vancomycin, gentamicin, ciprofloxacine and tigecycline in an experimental continuous veno-venous hemofiltration circuit with the use of both polyethyleneimine-treated polyacrylonitrile (PAN) and the polysulfone (PS) filter membranes. The crystalloid fluid dosed with one of antibiotic was pumped from a reservoir through a hemofiltration circuit (with PAN or PS membrane) and back to reservoir. All ultrafiltrate was also returned to the reservoir. During the procedures samples were collected from the post-hemofilter port at 5, 15, 30, 45, 60, 90, and 120 min. To determine spontaneous degradation of the antimicrobials, an additional bag with each study drug was prepared, which was not attached to the hemofiltration circuit. The samples from these bags were used as controls. In the case of vancomycin, gentamycin and tigecycline there was a statistically significant decrease in the drug concentration in the hemofiltration circuit in comparison to the control for PAN membrane (P < 0.05,P < 0.001,P < 0.001, respectively). In the case of ciprofloxacine adsorption was reversible and the drug concentrations increase to achieve the initial level for both membranes. Our studies indicated that a large portion of the administered dose of antibiotics may be adsorbed on a PAN membrane. In the case of gentamicin and tigecycline this amount is sufficiently big (over 90% of the administered dose) to be of clinical importance. In turn, adsorption on PS membranes is clearly lower (up to 10%) and may be clinically unimportant.
How averse are the UK general public to inequalities in health between socioeconomic groups? A systematic review
Authors: McNamara Simon , Holmes John , Stevely Abigail K. , Tsuchiya Aki
Published: October 2019

There is growing interest in the use of “distributionally-sensitive” forms of economic evaluation that capture both the impact of an intervention upon average population health and the distribution of that health amongst the population. This review aims to inform the conduct of distributionally sensitive evaluations in the UK by answering three questions: (1) How averse are the UK public towards inequalities in lifetime health between socioeconomic groups? (2) Does this aversion differ depending upon the type of health under consideration? (3) Are the UK public as averse to inequalities in health between socioeconomic groups as they are to inequalities in health between neutrally framed groups? EMBASE, MEDLINE, EconLit, and SSCI were searched for stated preference studies relevant to these questions in October 2017. Of the 2155 potentially relevant papers identified, 15 met the predefined hierarchical eligibility criteria. Seven elicited aversion to inequalities in health between socioeconomic groups, and eight elicited aversion between neutrally labelled groups. We find general, although not universal, evidence for aversion to inequalities in lifetime health between socioeconomic groups, albeit with significant variation in the strength of that preference across studies. Second, limited evidence regarding the impact of the type of health upon aversion. Third, some evidence that the UK public are more averse to inequalities in lifetime health when those inequalities are presented in the context of socioeconomic inequality than when presented in isolation.
Analysis of the shortest relay queue policy in a cooperative random access network with collisions
Authors: Saxena M. , Dimitriou I. , Kapodistria S.
Published: October 2019

The aim of this work concerns the performance analysis of systems with interacting queues under the join the shortest queue policy. The case of two interacting queues results in a two-dimensional random walk with bounded transitions to non-neighboring states, which in turn results in complicated boundary behavior. Although this system violates the conditions of the compensation approach due to the transitions to non-neighboring states, we show how to extend the framework of the approach and how to apply it to the system at hand. Moreover, as an additional level of theoretic validation, we have compared the results obtained with the compensation approach with those obtained using the power series algorithm and we have shown that the compensation approach outperforms the power series algorithm in terms of numerical efficiency. In addition to the fundamental contribution, the results obtained are also of practical value, since our analysis constitutes a first attempt toward gaining insight into the performance of such interacting queues under the join the shortest queue policy. To fully comprehend the benefits of such a protocol, we compare its performance to the Bernoulli routing scheme as well as to that of the single relay system. Extensive numerical results show interesting insights into the system’s performance.
Phenotyping reproductive stage chilling and frost tolerance in wheat using targeted metabolome and lipidome profiling
Authors: Cheong Bo Eng , Ho William Wing Ho , Biddulph Ben , Wallace Xiaomei , Rathjen Tina , Rupasinghe Thusitha W. T. , Roessner Ute , Dolferus Rudy
Published: October 2019

Introduction

Frost events lead to A$360 million of yield losses annually to the Australian wheat industry, making improvement of chilling and frost tolerance an important trait for breeding.

Objectives

This study aimed to use metabolomics and lipidomics to explore genetic variation in acclimation potential to chilling and to identify metabolite markers for chilling tolerance in wheat.

Methods

We established a controlled environment screening assay that is able to reproduce field rankings of wheat germplasm for chilling and frost tolerance. This assay, together with targeted metabolomics and lipidomics approaches, were used to compare metabolite and lipid levels in flag leaves of two wheat varieties with contrasting chilling tolerance.

Results

The sensitive variety Wyalkatchem showed a strong reduction in amino acids after the first cold night, followed by accumulation of osmolytes such as fructose, glucose, putrescine and shikimate over a 4-day period. Accumulation of osmolytes is indicative of acclimation to water stress in Wyalkatchem. This response was not observed for tolerant variety Young. The two varieties also displayed significant differences in lipid accumulation. Variation in two lipid clusters, resulted in a higher unsaturated to saturated lipid ratio in Young after 4 days cold treatment and the lipids PC(34:0), PC(34:1), PC(35:1), PC(38:3), and PI(36:4) were the main contributors to the unsaturated to saturated ratio change. This indicates that Young may have superior ability to maintain membrane fluidity following cold exposure, thereby avoiding membrane damage and water stress observed for Wyalkatchem.

Conclusion

Our study suggests that metabolomics and lipidomics markers could be used as an alternative phenotyping method to discriminate wheat varieties with differences in cold acclimation.
Integrating diversity of smallholder coffee cropping systems in environmental analysis
Authors: Acosta-Alba Ivonne , Boissy Joachim , Chia Eduardo , Andrieu Nadine
Published: October 2019

Purpose

Coffee represents an important trade asset internationally. Around 70% of global coffee production is provided by 25 million smallholders farmers. In recent decades, coffee systems have been transformed into more intensified systems of coffee monoculture. The general objectives of this paper are to provide a better picture of the traditional coffee cropping systems and postharvest processes on-farm and to assess the environmental impacts, integrating the diversity of smallholder cropping systems.

Methods

A Life Cycle Assessment from cradle to farm gate was performed for three cropping systems representative of Colombian coffee cultivation according to the associated crops and shadow trees: coffee alone (CA), coffee with transition shade (CTS), and coffee with permanent shade (CPS). The system studied includes inputs, agricultural production and postharvest operations using the wet method. The final product of farms is parchment bean coffee at farm gate. The technology used is representative of the average practices of smallholder coffee growers in the region. To address multiple functions of coffee, three functional units (FU) were selected: area by time (ha*year−1 unit area), productivity (ton of parchment coffee) and farmers income (1000 USD$). Seven midpoint categories were selected: climate change, acidification, terrestrial eutrophication, freshwater eutrophication, marine eutrophication, freshwater ecotoxicity, and water resource depletion.

Results and discussion

We present the life cycle inventory and impact assessment results from three types of cropping systems CA, CTS and CPS. For all FU, the CPS system has the lowest potential impact, excepted for marine eutrophication. CPS also has the highest coffee yields, however it has also the highest costs. Even if cropping system diversification is only one of multiple factors that influence environmental performance, agroforestry seems to be a promising path to reduce and mitigate environmental impacts by decreasing off-fam contributions (input fabrication).

Conclusions

Results show the possibility that diversified cropping systems have an influence when assessing potential environmental impacts of coffee at farm gate and differences found might be influenced by shading in traditional coffee systems. Future work is needed to consider the real potential of CTS cropping system including land use and carbon dynamics. Assessments including social indicators and the rest of the value chain in particular coffee industrial transformation and utilization are also needed since the consumption stages are also a key driver to reduce the environmental footprint of coffee.
Hypomagnesaemia and its determinants in a contemporary primary care cohort of persons with type 2 diabetes
Authors: Waanders Femke , Dullaart Robin P. F. , Vos Michel J. , Hendriks Steven H. , van Goor Harry , Bilo Henk J. G. , van Dijk Peter R.
Published: October 2019

Aims

Among persons with type 2 diabetes mellitus (T2DM) hypomagnesaemia has been reported in 14–48% of patients. This may be of significance given the emerging associations of hypomagnesaemia with glucometabolic disturbances and possibly even complications. We assessed the prevalence of hypomagnesaemia and its determinants, in a well-defined cohort of persons with T2DM treated in primary care.

Methods

Observational cohort study among persons with T2DM treated in primary care in the Northeast of the Netherlands. Magnesium was measured using a colorimetric endpoint assay (Roche). Hypomagnesaemia was defined as a serum magnesium level <0.70 mmol/L. Pearson correlations were performed to correlate variables with serum magnesium. Next, a stepwise backward regression model was made.

Results

Data of 929 persons (55% male) with a mean age of 65 (± 10) years, diabetes duration 6.5 [3.0–10.1] years, and HbA1c concentration 6.7 (± 0.7)% (50 (± 9) mmol/mol) were analysed. Serum magnesium was 0.79 (± 0.08) mmol/L. The percentage of persons with magnesium deficiency was 9.6%. Age, diabetes duration, BMI, HbA1c, use of metformin, sulfonylurea derivatives, and DPP4 inhibitors were negatively associated with magnesium concentrations. In contrast, LDL cholesterol and serum creatinine were positively associated serum magnesium.

Conclusions

Hypomagnesaemia was present in 9.6% of T2DM patients treated in primary care. This percentage is remarkably lower than reported previously, possibly due to the unselected nature of our population. Concerning T2DM-related factors, only BMI, HbA1c and the use of metformin, sulfonylurea derivatives and DPP4 inhibitors correlated negatively with magnesium concentrations.
Histone Methylations Define Neural Stem/Progenitor Cell Subtypes in the Mouse Subventricular Zone
Authors: Zhang Zhichao , Manaf Adeel , Li Yanjiao , Perez Sonia Peña , Suganthan Rajikala , Dahl John Arne , Bjørås Magnar , Klungland Arne
Published: October 2019

Neural stem/progenitor cells (NSPCs) persist in the mammalian brain throughout life and can be activated in response to the physiological and pathophysiological stimuli. Epigenetic reprogramming of NPSC represents a novel strategy for enhancing the intrinsic potential of the brain to regenerate after brain injury. Therefore, defining the epigenetic features of NSPCs is important for developing epigenetic therapies for targeted reprogramming of NSPCs to rescue neurologic function after injury. In this study, we aimed at defining different subtypes of NSPCs by individual histone methylations. We found the three histone marks, histone H3 lysine 4 trimethylation (H3K4me3), histone H3 lysine 27 trimethylation (H3K27me3), and histone H3 lysine 36 trimethylation (H3K36me3), to nicely and dynamically portray individual cell types during neurodevelopment. First, we found all three marks co-stained with NSPC marker SOX2 in mouse subventricular zone. Then, CD133, Id1, Mash1, and DCX immunostaining were used to define NSPC subtypes. Type E/B, B/C, and C/A cells showed high levels of H3K27me3, H3K36me3, and H3K4me3, respectively. Our results reveal defined histone methylations of NSPC subtypes supporting that epigenetic regulation is critical for neurogenesis and for maintaining NSPCs.
Impact of Barrier Breaching on Wetland Ecosystems under the Influence of Storm Surge, Sea-Level Rise and Freshwater Discharge
Authors: Li Xiaorong , Leonardi Nicoletta , Plater Andrew J.
Published: October 2019

Coastal wetland ecosystems and biodiversity are susceptible to changes in salinity brought about by the local effects of climate change, meteorological extremes, coastal evolution and human intervention. This study investigates changes in the salinity of surface water and the associated impacts on back-barrier wetlands as a result of breaching of a barrier beach and under the compound action of different surge heights, accelerated sea-level rise (SLR), river discharge and rainfall. We show that barrier breaching can have significant effects in terms of vegetation die-back even without the occurrence of large storm surges or in the absence of SLR, and that rainfall alone is unlikely to be sufficient to mitigate increased salinity due to direct tidal flushing. Results demonstrate that an increase in sea level corresponding to the RCP8.5 scenario for year 2100 causes a greater impact in terms of reedbed loss than storm surges up to 2 m with no SLR. In mitigation of the consequent changes in wetland ecology, regulation of relatively small and continuous river discharge can be regarded as a strategy for the management of coastal back-barrier wetland habitats and for the maintenance of brackish ecosystems. As such, this study provides a tool for scoping the potential impacts of storms, climate change and alternative management strategies on existing wetland habitats and species.
Guidelines on the use of fluoride for caries prevention in children: an updated EAPD policy document
Authors: Toumba K. J. , Twetman S. , Splieth C. , Parnell C. , van Loveren C. , Lygidakis N. Α.
Published: October 2019

Aim

To update the exisitng European Academy of Paediatric Dentistry (EAPD) 2009 fluoride guidelines.

Methods

Experts met in Athens, Greece duirng November 2018 for the following groups: I Fluoride toothpastes, II Fluoride gels, rinses and varnishes, III Fluoridated milk, fluoridated salt, tablets/lozenges and drops, IV Water fluoridation. Systematic reviews and meta-analyses were reviewed and discussed for each of the groups. The GRADE system was used to assess the quality of evidence which was judged as HIGH, MODERATE, LOW or VERY LOW based on the assessment of eight criteria which can influence the confidence of the results. Following the quality assessment, GRADE was then used to indicate the strength of recommendation for each fluoride agent as STRONG or WEAK/CONDITIONAL.

Results

Parents must be strongly advised to apply an age-related amount of toothpaste and assist/supervise tooth brushing until at least 7 years of age. The EAPD strongly endorses the daily use of fluoride as a major part of any comprehensive programme for the prevention and control of dental caries in children. Regardless of the type of programme, community or individually based, the use of fluoride must be balanced between the estimation of caries-risk and the possible risks of adverse effects of the fluorides. Fluoride use is considered safe when the manufacturer's instructions are followed. Preventive programmes should be re-evaluated at regular intervals and adapted to a patient's or population's needs and risks.

Conclusions

For the majority of European Countries, the EAPD recommends the appropriate use of fluoride toothpaste in conjunction with good oral hygiene to be the basic fluoride regimen.
Environmental Controls on the Distribution of Tidal Wetland Soil Organic Carbon in the Continental United States
Authors: Hinson A.L. , Feagin R.A. , Eriksson M.
Published: October 2019

Tidal wetlands are among the most valuable ecosystems in the world in terms of ecosystem service value, and the strategic management of their carbon resources is an important part of climate change mitigation. Tidal wetland soils contain relatively high quantities of soil organic carbon (SOC); yet there is little information about whether this SOC can be predicted based on easily identifiable environmental factors. We investigated how tidal wetland SOC density was distributed across the continental United States among various coastal locations, estuarine typologies, vegetation types, water regimes, and management regimes and found that knowledge of a wetland's coastal affiliation provided the most differentiation (whether on the East Coast, West Coast, or Gulf Coast). We then sought to identify whether SOC density was correlated with 47 different environmental variables and found that knowledge based on latitude and precipitation explained ~46% of the variance in SOC density for wetlands on the West Coast and Gulf Coast, respectively. Several other geographic, oceanic, terrestrial, and atmospheric factors were cross‐correlated along these axes, including oceanic salinity, temperature, and average catchment elevation. For the U.S. East Coast, SOC density was not simple to explain and was likely dependent on a wide range of interacting and complex factors. This synthetic work can provide a better understanding of how changing environmental and social conditions can lead to enhanced or degraded carbon sequestration rates in times of rapid global change.
The Imprint of Vegetation on Desert Dune Dynamics
Authors: Lee Dylan B. , Ferdowsi Behrooz , Jerolmack Douglas J.
Published: October 2019

Here we demonstrate the qualitative and quantitative influence that vegetation has on stabilizing desert dunes. We use topographic data to isolate translation and deformation of dune patterns, upwind of and across a sharp gradient of vegetation, at White Sands dune field, New Mexico. Barchanoid dunes are unstable due to an aerodynamic surface wave instability. The dynamics of vegetated parabolic dunes are different; deformation becomes localized, and random, once plant density reaches a critical value associated with the barchanoid‐parabolic transition. Plants stabilize dunes not only by slowing them down but also by shutting off the fundamental mechanism that generates new sand waves and destabilizes dunes. Increasing plant density downwind increases vegetation‐induced form drag and results in decreasing dune migration rate. We suggest that similar biological modulation of pattern‐forming instabilities may also occur in other landscapes.
Skilful Real‐Time Seasonal Forecasts of the Dry Northern European Summer 2018
Authors: Dunstone Nick , Smith Doug , Hardiman Steven , Eade Rosie , Gordon Margaret , Hermanson Leon , Kay Gillian , Scaife Adam
Published: October 2019

The Northern European summer of 2018 was the driest for 35 years with resulting impacts on health, agriculture, energy, and water resources. Here we show that this rainfall anomaly was well predicted by a real‐time seasonal forecast. An anticyclonic circulation anomaly was correctly forecast over the North Sea and Scandinavia in 2018 and also in the 1976 record dry summer. In both these exceptionally dry summers, a similar tripole anomaly pattern of North Atlantic sea surface temperatures was present. We perform perturbation experiments that reveal significant circulation, and European rainfall, responses due to changes in the Atlantic meridional temperature gradient. However, consistent with previous work, we find that the model dynamical response is weak relative to that observed and hence large ensembles are required to produce sufficiently skilful predictions. This case study illustrates the potential for the development of summer European climate services.
Multi‐Model Intercomparison of the Pan‐Arctic Ice‐Algal Productivity on Seasonal, Interannual, and Decadal Timescales
Authors: Watanabe Eiji , Jin Meibing , Hayashida Hakase , Zhang Jinlun , Steiner Nadja
Published: October 2019

Seasonal, interannual, and decadal variations in the Arctic ice‐algal productivity for 1980–2009 are investigated using daily outputs from five sea ice‐ocean ecosystem models participating in the Forum for Arctic Modeling and Observational Synthesis project. The models show a shelf‐basin contrast in the spatial distribution of ice‐algal productivity (ice‐PP). The simulated ice‐PP substantially varies among the four subregions (Chukchi Sea, Canada Basin, Eurasian Basin, and Barents Sea) and among the five models, respectively. The simulated annual total ice‐PP has no common decadal trend at least for 1980–2009 among the five models in any of the four subregions, although the simulated snow depth and sea‐ice thickness in spring are mostly declining. The model intercomparison indicates that an appropriate balance of stable ice‐algal habitat (i.e., sea‐ice cover) and enough light availability is necessary to retain the ice‐PP. The multi‐model averages show that the ice‐algal bloom timing shifts to an earlier date and that the bloom duration shortens in the four subregions. However, both the positive and negative decadal trends in the timing and duration are simulated. This difference in trends are attributed to temporal shifts among different types of ice‐algal blooms: long‐massive, short‐massive, long‐gentle, and short‐gentle bloom. The selected value for the maximum growth rate of the ice‐algal photosynthesis term is a key source for the inter‐model spreads. Understanding the simulated uncertainties on the pan‐Arctic and decadal scales is expected to improve coupled sea ice‐ocean ecosystem models. This step will be a baseline for further modeling/field studies and future projections.
Variable Raindrop Size Distributions in Different Rainbands Associated With Typhoon Fitow (2013)
Authors: Bao Xuwei , Wu Liguang , Tang Bi , Ma Leiming , Wu Dan , Tang Jie , Chen Haojun , Wu Lianyao
Published: October 2019

The microphysical characteristics of rain may vary in different rain regions of a tropical cyclone (TC), but few studies have demonstrated the differences in raindrop size distributions (RSDs) of convective rain in different rainbands of a specific TC. This study examines the RSD characteristics and evolution of convective rain within outer rainbands and a coastal‐front‐like rainband associated with Typhoon Fitow, based on observational data from a disdrometer at Shibo station in Shanghai, China, during 6–7 October 2013. Considering the fast passage of convective TC rainbands over the disdrometer and the low rain rate of stratiform rain in the outer area, this study proposes a modified rain‐type classification method based on the disdrometer data. This study indicates that convective outer‐rainband rain (ORR) and coastal‐front rain (CFR) have different rain parameters, three parameters of the gamma model, radar reflectivity–rain rate (Z‐R), and shape–slope (μ‐Λ) relationships. The convective ORR has higher concentrations at all drop sizes than the convective CFR as well as larger spectral width, leading to the greater rainfall rate. The different Z‐R relationships suggest the necessity of a variable relationship for quantitative precipitation estimation (QPE) in different rain regions of the TC. This study also demonstrates for the first time that the RSD evolution with increasing rain rate is different in various convective rainbands associated with Fitow, suggesting that different microphysical parameterization schemes may be required for different rainbands in TC models.
Upper Atmospheric Responses to Surface Disturbances: An Observational Perspective
Authors: Meng Xing , Vergados Panagiotis , Komjathy Attila , Verkhoglyadova Olga
Published: October 2019

We review observations on the coupling between Earth's surface disturbances and the upper atmosphere. In particular, we focus on the upper atmospheric responses to atmospheric acoustic‐gravity waves generated during impulsive surface disturbance events including earthquakes, tsunamis, volcanic eruptions, and explosions. We review the theoretical background for the generation and propagation of atmospheric acoustic‐gravity waves from surface disturbance events as well as of the ionospheric plasma response to such acoustic‐gravity waves. We review a variety of observational techniques that have been successfully utilized to detect upper atmospheric perturbations induced by surface disturbances and summarize the state‐of‐the‐art knowledge on the coupling processes learnt from these observations. Finally, we touch on some most recent advances in the field and propose directions for future research.
Surface Wave Reduction in Antenna Arrays Using Metasurface Inclusion for MIMO and SAR Systems
Authors: Alibakhshikenari Mohammad , Virdee Bal S. , See Chan H. , Abd‐Alhameed Raed A. , Falcone Francisco , Limiti Ernesto
Published: October 2019

An effective method is presented for suppressing mutual coupling between adjacent radiating elements which is based on metasurface isolation for multiple‐input multiple‐output (MIMO) and synthetic aperture radar (SAR) systems. This is achieved by choking surface current waves induced over the patch antenna by inserting a cross‐shaped metasurface structure between the radiating elements. Each arm of the cross‐shaped structure constituting the metasurface is etched with meander line slot. Effectiveness of the metasurface is demonstrated for a 2 × 2 antenna array that operates over six frequency subbands in X, Ku, and K bands. With the proposed technique, the maximum improvement achieved in attenuating mutual coupling between neighboring antennas is 8.5 dB (8–8.4 GHz), 28 dB (9.6–10.8 GHz), 27 dB (11.7–12.6 GHz), 7.5 dB (13.4–14.2 GHz), 13 dB (16.5–16.8 GHz), and 22.5 dB (18.5–20.3 GHz). Furthermore, with the proposed technique (i) minimum center‐to‐center separation between the radiating elements can be reduced to 0.26λ0, where λ0 is 8.0 GHz; (ii) use of ground‐plane or defected ground structures are unnecessary; (iii) use of short‐circuited via‐holes are avoided; (iv) it eliminates the issue with poor front‐to‐back ratio; and (v) it can be applied to existing arrays retrospectively.
Nogo receptor–vimentin interaction: a novel mechanism for the invasive activity of glioblastoma multiforme
Authors: Kang Yun Hee , Han Seung Ro , Jeon Hyungtaek , Lee Suhyuk , Lee Jisu , Yoo Seung-Min , Park Jong Bae , Park Myung-Jin , Kim Jong-Tae , Lee Hee Gu , Lee Myung-Shin , Lee Seung-Hoon
Published: October 2019

Nogo receptor (NgR) has been shown to inhibit the migration and invasion of human glioma cells. However, little is known regarding the regulatory mechanisms of NgR in glioblastoma multiforme (GBM). In this study, we propose a novel mechanism that regulates the maturation process of NgR through an interaction with vimentin. The inhibition of TGFβ1 activity by LY2109761 attenuated the migration/invasion of GBM cells by upregulating cell-surface NgR. Conversely, the treatment of GBM cells with TGFβ1 suppressed NgR maturation. We showed that NgR and vimentin interact, which could be a possible mechanism for the suppression of NgR maturation. The knockdown of vimentin suppressed the migration/invasion of GBM cells through the increased maturation of NgR. Finally, TCGA (The Cancer Genome Atlas) analysis also supported the association of NgR and vimentin. The maturation of NgR is regulated by the interaction of vimentin and NgR, which attenuates the invasive activity of GBM, and might be a potential therapeutic target for brain cancer.
Structural variation of the complete chloroplast genome and plastid phylogenomics of the genus Asteropyrum (Ranunculaceae)
Authors: He Jian , Yao Min , Lyu Ru-Dan , Lin Le-Le , Liu Hui-Jie , Pei Lin-Ying , Yan Shuang-Xi , Xie Lei , Cheng Jin
Published: October 2019

Two complete chloroplast genome sequences of Asteropyrum, as well as those of 25 other species from Ranunculaceae, were assembled using both Illumina and Sanger sequencing methods to address the structural variation of the cp genome and the controversial systematic position of the genus. Synteny and plastome structure were compared across the family. The cp genomes of the only two subspecies of Asteropyrum were found to be differentiated with marked sequence variation and different inverted repeat-single copy (IR-SC) borders. The plastomes of both subspecies contains 112 genes. However, the IR region of subspecies peltatum carries 27 genes, whereas that of subspecies cavaleriei has only 25 genes. Gene inversions, transpositions, and IR expansion-contraction were very commonly detected in Ranunculaceae. The plastome of Asteropyrum has the longest IR regions in the family, but has no gene inversions or transpositions. Non-coding regions of the cp genome were not ideal markers for inferring the generic relationships of the family, but they may be applied to interpret species relationship within the genus. Plastid phylogenomic analysis using complete cp genome with Bayesian method and partitioned modeling obtained a fully resolved phylogenetic framework for Ranunculaceae. Asteropyrum was detected to be sister to Caltha, and diverged early from subfamily Ranunculoideae.
Development, characterisation andin vitroevaluation of lanthanide-based FPR2/ALX-targeted imaging probes
Authors: Boltersdorf Tamara , Ansari Junaid , Senchenkova Elena Y. , Jiang Lijun , White Andrew J. P. , Coogan Michael , Gavins Felicity N. E. , Long Nicholas J.
Published: October 2019

Formyl Peptide Receptor (FPR)-targeted lanthanide complexes with long-lived emission in stimulated human neutrophils.
On the development of a new approach to the design of lanthanide-based materials for solution-processed OLEDs
Authors: Kozlov Makarii I. , Aslandukov Andrey N. , Vashchenko Andrey A. , Medvedko Alexey V. , Aleksandrov Alexey E. , Grzibovskis Raitis , Goloveshkin Alexander S. , Lepnev Leonid S. , Tameev Alexey R. , Vembris Aivars , Utochnikova Valentina V.
Published: October 2019

The targeted design of lanthanide-based emitters for solution-processed OLEDs was aimed at the combination of high luminescence efficiency with solubility and charge carrier mobility.
Correction: Biosynthesized silver nanorings as a highly efficient and selective electrocatalysts for CO2 reduction
Authors: Pan Yani , Paschoalino Waldemir J. , Bayram Serene S. , Blum Amy Szuchmacher , Mauzeroll Janine
Published: October 2019

Correction for ‘Biosynthesized silver nanorings as a highly efficient and selective electrocatalysts for CO2 reduction’ by Yani Pan et al., Nanoscale, 2019, 11, 18595–18603.
Both increasing the Iso-to-Col transition and lowering the solidifying temperatures of a triazine-based dendrimer by introducing CN polar groups in the dendritic core
Authors: Lee Cheng-Hua , Huang Chun-Chi , Li Chia-Ying , Lai Long-Li , Lee Jey-Jau , Hsu Hsiu-Fu
Published: October 2019

The CN polarity in the linker effectively broadens the mesogenic range and lowers the solidifying temperature of the dendrimer.
Electrically small, planar, wideband filtering antenna with dual ring patches
Authors: Tang Ming‐Chun , Li Chaofang , Chen Yingjie
Published: October 2019

A simple, planar, electrically small antenna with both wide bandwidth and good out‐of‐band filtering selectivity is presented. The proposed filtering antenna is mainly composed of a small driven patch and a slotted ground plane. Two slots are etched in the ground plane to form two square ring patches that can generate a new resonant mode and two radiation zeros, and a T‐shaped stub is loaded not only to enhance the impedance bandwidth but also to increase the out‐of‐band rejection level. A prototype is fabricated and measured. The measured −10 dB fractional impedance bandwidth is 23.05% (2.61–3.29 GHz) centred at 2.95 GHz with the realised gain values 2.95 ± 0.34 dBi in the operational band, with two radiation zeros located at 2.27 and 3.62 GHz, respectively, even with electrically small size ka = 0.98. The experimental results are in good agreement with the simulated values.
Visual tracking enhancement by trajectory simulation based on hidden semi‐Markov model
Authors: Ha S. , Kwon J.
Published: October 2019

In this Letter, the authors present a novel tracking system, in which tracking accuracy can be enhanced by trajectory simulation. They generate synthetic trajectories based on observed trajectories by adopting the hidden semi‐Markov model (HSMM). In the course of trajectory simulation, HSMM can encode representative states and speeds of the targets. The simulated trajectories enforce the proposed tracker to focus on the areas where targets will move at following frames. Experimental results demonstrate that it is easy to integrate the proposed trajectory simulation into traditional visual tracking methods and the trajectory simulation can considerably improve the accuracy of visual trackers.
1.3‐µm buried‐heterostructure VCSELs with GaAs/AlGaAs metamorphic DBRs grown by MOCVD
Authors: Ohiso Y. , Sato T. , Shindo T. , Matsuzaki H.
Published: October 2019

The authors report buried‐heterostructure long‐wavelength VCSELs with GaAs/AlGaAs metamorphic DBRs, which has a potential for low thermal resistance and operation in the single transverse mode with a large emission area. In spite of their being upside‐up and unmounted, they achieve CW operation at 17°C, and VCSELs with a 15‐µm mesa exhibit single‐mode operation.
Active common‐mode filter for capacitive‐coupled isolated signalling
Authors: Angerer M. , Schwanninger R. , März M.
Published: October 2019

Capacitive coupling is a well‐established principle in isolated signalling. A major challenge esp. in power electronics is common‐mode transient immunity caused by the displacement currents at the coupling capacitors. Digital isolator integrated circuits (ICs) employ modulated signalling, the authors propose an active filter circuit to remove common‐mode components from baseband signals. This allows for reliable data transmission during transients in power semiconductor control, AC‐coupled RS‐485 or transformer‐less Ethernet. The filter structure is simple and consists of two current mirrors, one for positive transients, and one for the negative. A current on one differential signal line is ‘mirrored’ onto the other, common‐mode currents are conducted to ground. Differential signals are minimally affected. The proposed filter is verified in simulation and experiment: baseband signalling with 50 Mbps in presence of 30 kV/ burst transients is achieved using discrete semiconductors. Even better results are expected when monolithically embedding the filter in an integrated circuit.
Tractable performance analysis of small‐cell networks with a novel bounded path loss model
Authors: Chen Chen , Yang Songjiang , Zhang Jiliang , Chu Xiaoli , Zhang Jie
Published: October 2019

The analysis of dense small‐cell networks has largely relied on the use of either unbounded path loss models that may violate the conservation of energy at very short distances, or bounded path loss models that are not tractable. In this Letter, the authors derive the coverage probability and area spectral efficiency (ASE) in closed‐forms for dense small‐cell networks by using a novel bounded path loss model. Their analytical results demonstrate that the coverage probability will monotonically decrease with the increase of base station (BS) density, and the ASE will first increase with the BS density and then reduce to zero when the network becomes ultra dense. They also give the closed‐form expression of the optimal BS density that maximises the ASE.
High step‐down/high step‐up interleaved bidirectional DC–DC converter with low voltage stress on switches
Authors: Mousavinezhad Fardahar Sara , Sabahi Mehran
Published: October 2019

A DC–DC bidirectional converter which has low voltage stress on its semiconductor elements is presented in this study. This study presents a novel interleaved coupled‐inductor‐based non‐isolated bidirectional DC–DC converter which is able to provide a high voltage gain conversion ratio. The high voltage gain of the proposed converter is achieved through its symmetrical topology with coupled inductors in its structure. Based on the fact that the voltage of the high‐voltage side is shared between the two separate modules of the converter, the voltage stress across the switches is decreased. There are two blocking capacitors in the primary side, which help the converter to have symmetrical topology. Also, the switching pattern of the proposed converter is simple and the converter is able to provide a single voltage gain for the whole range of duty cycle. The theoretical results are approved through the prototype of the converter for 400 W.
Electricity theft detection by sources of threats for smart city planning
Authors: Otuoze Abdulrahaman Okino , Mustafa Mohd Wazir , Mohammed Olatunji Obalowu , Saeed Muhammad Salman , Surajudeen‐Bakinde Nazmat Toyin , Salisu Sani
Published: October 2019

Smart city adoption and deployment has taken the centre stage worldwide with its realisation clearly hinged on energy efficiency, but its planning is threatened by the vulnerability of smart grids (SGs). Adversaries launch attacks with various motives, but the rampaging electricity theft menace is causing major concerns to SGs deployments and consequently, energy efficiency. Smart electricity meters deployments via the advanced metering infrastructure present promising solutions and even greater potential as it provides adequate data for analytical inferences for achieving proactive measures against various cyberattacks. This study suggests the sources of threats as the first step of such proactive measures of curbing electricity thefts. It provides a framework for monitoring, identifying and curbing the threats based on factors indicative of electricity thefts in a smart utility network. The proposed framework basically focuses on these symptoms of the identified threats indicative of possible electricity theft occurrence to decide on preventing thefts. This study gives a useful background to smart city planners in realising a more reliable, robust and secured energy management scheme required for a sustainable city.
An electric power trading framework for smart residential community in smart cities
Authors: Hanumantha Rao Bokkisam , Arun Saravana Loganathan , Selvan Manickavasagam Parvathy
Published: October 2019

This study proposes a multi‐agent‐based framework for Peer‐to‐Peer (P2P) power trading in a locality electricity market (LEM) for self‐interested smart residential prosumers. In LEM, prosumers may sell (buy) their excess generation (demand) at a profitable market prices compared to utility prices to achieve a win–win outcome. In LEM, three agents namely locality electricity trading system (LETS), utility and prosumer act together to achieve P2P power trading in a day‐ahead market. LETS computes the internal market prices employing any one of the market‐clearing mechanisms and broadcasts it to the prosumers. Prosumers optimise the generation‐demand schedule for the next day using residential energy management and trading system to achieve minimum electricity bill. The performance of the proposed framework is validated through different case studies on a residential locality with ten prosumers. The simulation is carried out using MATLAB parallel computation tool box and the load data is collected from the residential locality of National Institute of Technology Tiruchirappalli, India. It is evident from the simulation results that all the participants are economically benefited by P2P power trading. It is also found that the SDR mechanism in P2P outperforms and reduces the locality electricity bill by 27–68% under different operating conditions.
Study on the start‐up and fault‐restart strategies and reactive power analysis of DC distribution systems
Authors: Li Rui , Sun Lijing , Yang Linze , Gu Hanwen , Wang Yueqi , Jiao Zaibin
Published: October 2019

The DC distribution network is becoming the basic supporting component of the urban distribution network. A variety of power supplies, loads, and energy storage devices can be directly integrated into a DC distribution network, which can improve the economical and energy efficiency of the power system. This study proposes two charging strategies, two‐stage charging and one‐by‐one charging, to make the converter start up safely or quickly return to the normal operation state after the fault clearance. Owing to the existence of numerous DC capacitors in voltage source converters, the reactive power consumption in the start‐up process needs to be explicitly calculated. Mathematical expressions of reactive power requirements for different charging strategies are investigated in detail, from where it can be seen that the current‐limiting resistance can significantly affect the reactive power and the entire charging time. Simulation results show that the AC voltage can be seriously affected by the oscillation of the reactive power, which will lead to voltage drop and waveform distortion in mode switching.
Study on silicon drift detector efficiency using Monte–Carlo simulation and experimental methods
Authors: Guo Siming , Wu Jinjie , Zhang Jian , Fan Zihao , Che Weina , Li Mengshi , Hou Dongjie , Wang Ji
Published: October 2019

The energy calibration and efficiency calibration of one silicon drift detector (SDD) are introduced here. The energy calibration is achieved using four radioactive sources, and the linear correlation coefficient is close to one. The efficiency curve of the SDD is obtained by Monte–Carlo simulations from 0.5 keV to 40 keV. Then, the efficiency of the SDD is calibrated using two radioactive sources. The results of experiments are compared with the calculated and the relative deviation are within 5.6%.
Sliding mode‐based velocity and torque controllers for permanent magnet synchronous motor drives system
Authors: Zhao Kaihui , Yin Tonghuan , Zhang Changfan , Li Xiangfei , Chen Yue , Li Tao , He Jing
Published: October 2019

To minimise the torque ripple for vector control of interior permanent magnet synchronous motor (IPMSM) of railway traction system, this study proposes a new velocity, torque and current three‐loop control system, and designs a velocity and torque sliding mode controller (SMC) for permanent magnet synchronous motor (PMSM) driven system. First, the mathematical model of IPMSM is described and the new velocity and torque closed‐loop control system for PMSM is designed. Second, the velocity SMC and torque SMC are designed. The fast convergence of the motor velocity and torque is realised, and the torque ripple is reduced effectively. The stability of the designed SMC is analysed. Finally, the effectiveness of the proposed scheme was compared with PI by simulations and experiments. The results show that the proposed method has good control performance and strong robustness.