bluuebunny/crossref_metadata_2025 huggingface dataset:
Ruptures revoked: why the Central African Republic's unprecedented crisis has not altered deep-seated patterns of governance
Authors: Glawion Tim , de Vries Lotje
Published: August 2018

The Central African Republic experienced unprecedented violence between 2012 and 2014. We analyse three recent ruptures that developed as a result of this crisis, suggesting a break with the country's past. First, the Séléka rebellion that started in 2012; second, the establishment of a robust UN Peacekeeping mission in 2014; and finally, the democratic election of a civilian president in 2016. However, three deep-rooted patterns of governance have in each case transformed these ruptures. A history of outsourced politics, a plurality of violence and peripheral neglect push actors to perpetuate the violent past rather than breaking with it. We conclude that after an initial attempt to break with the CAR's long-term political economic trends, rebel groups, the UN mission and the democratic government have backtracked and now risk reinforcing the violence that mark politics and everyday life in the country.
Beyond post-apartheid politics? Cleavages, protest and elections in South Africa
Authors: Paret Marcel
Published: August 2018

Declining electoral support for South Africa's ruling party, the African National Congress (ANC), suggests a potential weakening of the anti-apartheid nationalism that defined the immediate post-apartheid period. Using two surveys of voters in primarily poor and working-class black areas, conducted during the 2014 (national) and 2016 (local) elections, as well as three case studies of protest by workers, poor communities and students, this article examines the social cleavages and political dynamics that underpinned deepening political competition. Results show that voting decisions varied according to gender, age, ethnicity and receipt of welfare benefits. Different public provisions mattered most during national versus local elections, demonstrating that voters paid close attention to government operations. Underscoring political fluidity, some instances of protest reinforced ANC dominance while others fed into support for the opposition. The findings challenge notions of uncontested one party dominance, revealing instead that some poor black voters are critically evaluating the ANC's performance and developing oppositional political identities.
Going beyond dyadic consultation relationships: information exchange in multi-step participation procedures
Authors: Fink Simon , Ruffing Eva
Published: August 2018

For decades, political scientists have observed the diffusion of complex governance arrangements including public participation procedures to ameliorate the democratic deficit inherent in these often-opaque structures. This article asks how the information provided in consultation statements is used by the consulting actors. To account for the multi-step character, the article combines exchange theory with a principal-agent approach, acknowledging that several actors in a delegation chain might be interested in the provided information. We use a typical case of a multi-step procedure – participation in German grid development – to test both theories. Neither the private firms nor the regulator use information provided in their own consultations, contradicting exchange theory. But the regulator considers ecological submissions made in the firms’ consultation, as the principal-agent approach suggests. Thus, a principal-agent approach allows us to find influence of consultation statements that exchange theory cannot detect.
A survey on routing problems and robotic systems
Authors: Macharet Douglas G. , Campos Mario F. M.
Published: August 2018

Planning paths that are length or time optimized or both is an age-long problem for which numerous approaches have been proposed with varied degree of success depending on the imposed constraints. Among classical instances in the literature, the Traveling Salesman Problem and the Vehicle Routing Problem have been widely studied and frequently considered in the realm of mobile robotics. Understandably, the classical formulation for such problems do not take into account many different issues that arise in real-world scenarios, such as motion constraints and dynamic environments, commonly found in actual robotic systems, and consequently the solutions have been generalized in several ways. In this work, we present a broad and comprehensive review of the classical works and recent breakthroughs regarding the routing techniques ordinarily used in robotic systems and provide references to the most fundamental works in the literature.
A Markley Variables-based Attitude Estimation Method Using Optical Flow and a Star Vector for Spinning Spacecraft
Authors: Ning Xiaolin , Ding Zonghe , Xu Mingzhu , Fang Jiancheng , Liu Gang
Published: August 2018

Markley variables have advantages of slow variation, easy numerical integration and high precision in describing the attitude of spinning spacecraft. Previous attitude estimation methods based on Markley variables for spinning spacecraft usually employ a sun vector from the sun sensor, a magnetic vector from the magnetometer, or the angular rate from the gyro as the measurement. This paper proposes a Markley variables-based attitude estimation method using optical flow and a star vector from a star sensor as the measurement, where optical flow provides rate information and the star vector provides direction information. This method can estimate the direction of the spin axis and spin angular rate very well by using only one star sensor. In addition, the star sensor has higher accuracy than the traditional sun sensor and magnetometer, and the star sensor can also replace the gyro in case the gyro is out of action. The impact factors of this method are also analysed, which include spin angular rate, spin axis orientation and spacecraft moment of inertia tensor error.
Who Owns My Autonomous Vehicle? Ethics and Responsibility in Artificial and Human Intelligence
Authors: HARRIS JOHN
Published: August 2018

This article investigates both the claims made for, and the dangers or opportunities posed by, the development of (allegedly), aspiring or “would-be” autonomous vehicles and other artificially superintelligent machines. It also examines the dilemmas posed by the fact that these individuals might develop ideas above their station. These ideas may also limit or challenge the legitimacy of the proposed management and safety strategies that might be devised to limit the ways in which they might function or malfunction.
Appropriate use of a beta-blocker in paediatric coronary CT angiography
Authors: Watanabe Hirofumi , Kamiyama Hiroshi , Kato Masataka , Komori Akiko , Abe Yuriko , Ayusawa Mamoru
Published: August 2018

Background

There is no standard dose or protocol for beta-blocker administration as preconditioning in children undergoing coronary CT angiography.

Methods

A total of 63 consecutive patients, with a mean age of 10.0±3.1 years, who underwent coronary CT angiography to assess possible coronary complications were enrolled in a single-centre, retrospective study. All patients were given an oral beta-blocker 1 hour before coronary CT angiography. Additional oral beta-blocker or intravenous beta-blocker was given to those with a high heart rate. We compared image quality, radiation exposure, and adverse events among the patients without additional beta-blocker, with additional oral beta-blocker, and with additional intravenous beta-blocker.

Results

There were no significant differences in image quality or radiation exposure among the groups. The heart rate just before scanning was significantly correlated with image quality (p<0.001, r=−0.533) but was not correlated with radiation exposure (p=0.45, r=0.096). There were no adverse events related to any allergic reaction, thereby showing the effectiveness of the beta-blocker.

Conclusion

Initial oral beta-blocker administration (0.8 mg/kg/dose) should be administered to all children undergoing coronary CT angiography. Additional intravenous beta-blocker should be given to those with poor heart rate control to improve image quality without increasing radiation exposure or allowing adverse events.
A neural approach for inducing multilingual resources and natural language processing tools for low-resource languages
Authors: ZENNAKI O. , SEMMAR N. , BESACIER L.
Published: August 2018

This work focuses on the rapid development of linguistic annotation tools for low-resource languages (languages that have no labeled training data). We experiment with several cross-lingual annotation projection methods using recurrent neural networks (RNN) models. The distinctive feature of our approach is that our multilingual word representation requires only a parallel corpus between source and target languages. More precisely, our approach has the following characteristics: (a) it does not use word alignment information, (b) it does not assume any knowledge about target languages (one requirement is that the two languages (source and target) are not too syntactically divergent), which makes it applicable to a wide range of low-resource languages, (c) it provides authentic multilingual taggers (one tagger forNlanguages). We investigate both uni and bidirectional RNN models and propose a method to include external information (for instance, low-level information from part-of-speech tags) in the RNN to train higher level taggers (for instance, Super Sense taggers). We demonstrate the validity and genericity of our model by using parallel corpora (obtained by manual or automatic translation). Our experiments are conducted to induce cross-lingual part-of-speech and Super Sense taggers. We also use our approach in a weakly supervised context, and it shows an excellent potential for very low-resource settings (less than 1k training utterances).
What Are We Talking about When We Talk about Digital Protectionism?
Authors: AARONSON SUSAN ARIEL
Published: August 2018

For almost a decade, executives, scholars, and trade diplomats have argued that filtering, censorship, localization requirements, and domestic regulations are distorting the cross-border information flows that underpin the internet. Herein I use process tracing to examine the state and implications of digital protectionism. I make five points: First, I note that digital protectionism differs from protectionism of goods and other services. Information is intangible, highly tradable, and some information is a public good. Secondly, I argue that it will not be easy to set international rules to limit digital protectionism without shared norms and definitions. Thirdly, the US, EU, and Canada have labeled other countries policies’ protectionist, yet their arguments and actions sometimes appear hypocritical. Fourth, I discuss the challenge of Chinese failure to follow key internet governance norms. China allegedly has used a wide range of cyber strategies, including distributed denial of service (DDoS) attacks (bombarding a web site with service requests) to censor information flows and impede online market access beyond its borders. WTO members have yet to discuss this issue and the threat it poses to trade norms and rules. Finally, I note that digital protectionism may be self-defeating. I then draw conclusions and make policy recommendations.
CHABAUTY LIMITS OF ALGEBRAIC GROUPS ACTING ON TREES THE QUASI-SPLIT CASE
Authors: Stulemeijer Thierry
Published: August 2018

Given a locally finite leafless tree $T$, various algebraic groups over local fields might appear as closed subgroups of $\operatorname{Aut}(T)$. We show that the set of closed cocompact subgroups of $\operatorname{Aut}(T)$ that are isomorphic to a quasi-split simple algebraic group is a closed subset of the Chabauty space of $\operatorname{Aut}(T)$. This is done via a study of the integral Bruhat–Tits model of $\operatorname{SL}_{2}$ and $\operatorname{SU}_{3}^{L/K}$, that we carry on over arbitrary local fields, without any restriction on the (residue) characteristic. In particular, we show that in residue characteristic $2$, the Tits index of simple algebraic subgroups of $\operatorname{Aut}(T)$ is not always preserved under Chabauty limits.
CHABAUTY LIMITS OF SIMPLE GROUPS ACTING ON TREES
Authors: Caprace Pierre-Emmanuel , Radu Nicolas
Published: August 2018

Let$T$be a locally finite tree without vertices of degree $1$. We show that among the closed subgroups of$\text{Aut}(T)$acting with a bounded number of orbits, the Chabauty-closure of the set of topologically simple groups is the set of groups without proper open subgroup of finite index. Moreover, if all vertices of$T$have degree${\geqslant}3$, then the set of isomorphism classes of topologically simple closed subgroups of$\text{Aut}(T)$acting doubly transitively on$\unicode[STIX]{x2202}T$carries a natural compact Hausdorff topology inherited from Chabauty. Some of our considerations are valid in the context of automorphism groups of locally finite connected graphs. Applications to Weyl-transitive automorphism groups of buildings are also presented.
A Soldier’s Faith: The Civil War Experiences and Reflections of William Porcher DuBose
Authors: Slocum Robert B.
Published: August 2018

The noted Episcopal theologian William Porcher DuBose was a seminarian when the American Civil War began. He was torn between continuing his studies for ordination and joining the Confederate Army. He felt duty bound to defend his homeland, and he served heroically, wounded in combat, and taken as a prisoner of war. Troubled by the senselessness and inhumanity of war, he was eventually ordained and served as a military chaplain. He devoted himself to faith and ministry when he realized his country and culture were lost. DuBose vividly presents his views on war and faith in his wartime correspondence with his fiancée and later wife Anne Barnwell Perroneau, and other writings. His experiences of loss and poverty were the basis for his theology of the cross and his understanding of the role of suffering in the Christian life, and he subsequently dedicated himself to faith, peace, and reconciliation.
Effect of biofertilizers and diatomaceous earth on life and movement of subterranean termites under laboratory conditions
Authors: Ahmed Sohail , Hassan Babar , Farooq Muhammad Umer
Published: August 2018

The presence of biofertilizers can affect the life and movement of subterranean organisms in the soil. In the current study, the effect of three biofertilizers (Unigrow, Rhizogold and Rhizogold Plus) alone and in combination with diatomaceous earth (DE) and insecticides on mortality and movement of subterranean termites, Coptotermes heimi (Wasmann), was investigated under laboratory conditions. The mortality of termites in soil mixed with biofertilizers was low as compared to the control treatment, which led to significant mortality. Length of galleries formed by termites with the addition of Unigrow in the soil was significantly higher as compared to the other two biofertilizers and control treatments. Mortality increased in the presence of insecticides and DE in the soil substrate. Unigrow mixed soil having chlorfenapyr had maximum mortality and minimum gallery length followed by Rhizogold and Rhizogold Plus. The addition of DE and insecticide further enhances mortality, and we recommend that some toxic elements should be incorporated in biofertilizers to control subterranean termites.
An analysis of the feasibility of an extreme operational risk pool for banks
Authors: Li Yifei , Allan Neil , Evans John
Published: August 2018

Operational risk events in banks include extreme events with significant losses being incurred and with substantial impact on share prices. A pooling arrangement between banks that would be able to reduce overall costs and reduce share price impacts would seem desirable, but one of the major inhibiting factors to establish the feasibility of such a pooling arrangement is that statistical models of these extreme events are difficult to build with any reliability. This paper uses both quantitative and qualitative analysis of operational risk losses for EU and US banks over the period 2008–2014 to establish the feasibility of creating a pooling arrangement between the banks and concludes that such an arrangement might be feasible but would require compulsory membership of the pool and capping of losses.
Wideband radar cross-section reduction of a microstrip antenna using slots
Authors: Zhang Jiakai , Li Haixiong , Zheng Qi , Ding Jun , Guo Chenjiang
Published: August 2018

In this study, a new microstrip patch antenna with wideband radar cross-section (RCS) reduction is presented. The RCS of the proposed antenna was reduced by subtracting the current-direction slots of the patch, with the radiation performance sustained not only for the current-direction subtraction, but also for the no modification in the ground plane. Modified and reference antenna were fabricated and measured. The simulation and measurement results showed that the modified antenna reduced the in-band and out-band RCS simultaneously with no detriment to the radiation performance. In the frequency band from 3.9 to 8.1 GHz, the RCS of the modified antenna was reduced in the whole band compared with the RCS of the reference antenna. The maximum RCS reduction was 7 dB at a frequency of 6.7 GHz.
Localization Effects on the Dissipation of Gravity Wave Packets in the Upper Mesosphere and Lower Thermosphere
Authors: Heale C. J. , Walterscheid R. L. , Snively J. B.
Published: August 2018

Gravity waves not subject to breaking or filtering will dissipate due to viscosity and thermal conduction in the thermosphere. However, the evolutions of wave packets, and the altitudes they reach, are highly dependent upon the spectral content. In this paper, a 2‐D numerical model is used to investigate the effect of spatial localization (and thus spectral content) of a wave packet on its dissipation, dispersion, and spectral evolution. It is found that most wave packets launched below the thermosphere evolve to smaller central vertical wavelengths as the faster, longer vertical wavelength components reach the dissipative thermosphere and are removed first, leaving the shorter, slower components to become dominant at later times. This effect is greater for more spatially localized packets (spectrally broadband) as rapid dispersion leads to the rapid spreading of the wave over large altitude regions that could be interpreted as different waves (i.e., from different sources) by instruments observing different altitudes. Dispersion can also be accelerated by the refractive effects of the thermospheric temperature gradient. Initially, Gaussian broadband packets can evolve into asymmetric distributions which are not well described by standard assumptions (e.g., Gaussian packets), requiring instead numerical simulation to properly describe them. In the case that the vertical scale is smaller than the scale height, and dissipation acts immediately on the packet (i.e., it is generated in situ in the dissipative thermosphere), then the scale‐dependent nature of dissipation removes the shorter wavelengths components first, leading to the spectrum evolving toward larger vertical wavelengths.
Observations From a Global Database of Impact Craters on Mercury With Diameters Greater than 5 km
Authors: Herrick R. R. , Bateman E. M. , Crumpacker W. G. , Bates D.
Published: August 2018

We created a global database of Mercurian impact craters with diameters over 5 km, excluding obvious secondary craters. For craters over 10 km in diameter, we assessed basic morphological parameters, including an evaluation of whether significant postimpact filling occurred, the nature of any central structure, a three‐point assessment of degradation state, and a recording of the presence of rays and other atypical features. We used the database to evaluate the spatial patterns of different subsets of the crater population. The distribution of craters with diameters of 5 to 10 km compared to the distribution of larger craters shows many background secondaries associated with primary craters with diameters over 150 km, and their abundance would distort crater counts for surface dating. Counting only unfilled craters gives an estimate of the last possible date of endogenic geologic activity on a surface. Only a third of craters with diameters over 20 km are classified as unfilled, and the highest spatial density of unfilled craters is about half the total population at the same location. Our results support a globally rapid cessation in volcanism, with variations in the volume of late stage volcanism accounting for variations in the number of filled craters. We see regional variations of interior morphology for craters ~100 km in diameter that do not obviously correlate with other patterns derived from surface observations; our observations imply that there are variations in the mechanical properties of the upper several kilometers of crust.
Response of Surface Topography to Basal Variability Along Glacial Flowlines
Authors: Ng Felix S. L. , Ignéczi Ádám , Sole Andrew J. , Livingstone Stephen J.
Published: August 2018

Predicting the amplitude and distribution of surface undulations on ice sheets and glaciers is useful because of their influence on surface mass and energy balance, atmospheric boundary layer processes, and supraglacial meltwater routing. We develop an approximate method of calculating the surface elevation response due to spatial perturbations in basal topography and slipperiness, on two‐dimensional flow sections whose thickness, surface slope, and basal slip ratio vary along flow. Our main result is an integral expressing nonuniform transfer of basal variability to the surface. It uses published Fourier transfer functions derived through perturbing plane‐slab Stokes flow but circumvents the need to subwindow the spatial domain to estimate the response. We test the method on ice flow synthesized by a finite‐element model of Stokes flow with constant viscosity and known basal topography and slipperiness perturbations; in this case, it predicts the observed size and shape of the surface undulations well, capturing more than 90% of their variance. Application of the method to the central flowline of Columbia Glacier, Alaska, and a flowline on the Greenland Ice Sheet ending on Nordenskiöld Glacier, using knowledge of the approximate bed topography and ignoring the unknown slipperiness forcing, yields less faithful prediction of their surface undulations (40–50% of their variance) but demonstrates the method's potential to reproduce their qualitative features. We discuss the factors limiting the method's performance on real flowlines.
Influence of Solar Activity on Penetration of Traveling Planetary‐Scale Waves From the Troposphere Into the Thermosphere
Authors: Koval A. V. , Gavrilov N. M. , Pogoreltsev A. I. , Shevchuk N. O.
Published: August 2018

In this study, numerical simulations of planetary‐scale waves (PSWs), generated in the troposphere, were performed for altitudes from the Earth's surface up to 300 km. The influence of thermospheric effects of solar activity (SA) on the amplitudes and phases of westward traveling PSWs with zonal wave numbers 1 and 2 and periods 4–16 days propagating from the troposphere was simulated. Such simulations for a large number of PSW modes in the thermosphere were made for the first time. The effects of SA changes at altitudes above 100 km were involved in the general circulation model MUAM. The ionospheric conductivities for minimum and maximum SA levels were included into the MUAM. The simulation results were averaged over two ensembles of model runs with different PSW phases for conditions corresponding to the high and low SA levels for January–February. PSW atmospheric refractivity index and Eliassen‐Palm flux were calculated. They correspond to simulated changes in PSW amplitudes. Changes in the zonal velocity and temperature caused by the SA variations can modify spatial distributions of the westward traveling PSWs. Wave amplitudes significantly (up to 100%) decrease at the thermospheric heights under high SA, which is accompanied by decreasing vertical component of the Eliassen‐Palm flux. The 7‐, 10‐, and 16‐day PSWs could have larger partial reflection and worse propagation conditions than the 4‐ and 5‐day waves in the Southern Hemisphere under the high SA. At altitudes below 100 km, minor differences in zonal velocity and PSW amplitudes between high and low SA are found.
Effect of Gas Flow Rate on Hydrate Formation Within the Hydrate Stability Zone
Authors: Meyer Dylan W. , Flemings Peter B. , DiCarlo David
Published: August 2018

We form methane hydrate in brine‐saturated, coarse‐grained samples, under hydrate‐stable conditions, by injecting methane vapor at various flow rates. Decreasing the flow rate results in higher hydrate saturation, lower brine saturation, a smaller affected volume, and larger average pressure differentials across the sample. We interpret that the longer execution times at lower flow rates allow for additional methane transport and hydrate formation at the hydrate‐brine interface. As a result, the hydrate skin is thicker at lower flow rates and thus is capable of sustaining larger pressure differentials. In several experiments, we stop brine flow and supply methane gas to the sample for an additional 800 hrs. During this period, hydrate continues to form, pressure differentials develop, and the bulk density changes within the affected volume. We interpret that there is gas present in the sample that is disconnected from the gas source. Hydrate forms around the disconnected gas due to methane transport through the skin that surrounds it, causing the internal gas pressure to decline and leading to inward collapse and net volume decrease. This lowers the brine pressure and creates a differential pressure across the sample that induces gas flow. This study indicates that lower gas flow rates through the hydrate stability zone can produce very high saturations of hydrate but require a larger differential pressure to sustain flow. Ultimately, this process is an alternative mechanism for sustained upward gas flow and hydrate formation far above the base of the hydrate stability zone.
Subannual and Seasonal Variability of Atlantic‐Origin Waters in Two Adjacent West Greenland Fjords
Authors: Carroll D. , Sutherland D. A. , Curry B. , Nash J. D. , Shroyer E. L. , Catania G. A. , Stearns L. A. , Grist J. P. , Lee C. M. , de Steur L.
Published: August 2018

Greenland fjords provide a pathway for the inflow of warm shelf waters to glacier termini and outflow of glacially modified waters to the coastal ocean. Characterizing the dominant modes of variability in fjord circulation, and how they vary over subannual and seasonal time scales, is critical for predicting ocean heat transport to the ice. Here we present a 2‐year hydrographic record from a suite of moorings in Davis Strait and two neighboring west Greenland fjords that exhibit contrasting fjord and glacier geometry (Kangerdlugssuaq Sermerssua and Rink Isbræ). Hydrographic variability above the sill exhibits clear seasonality, with a progressive cooling of near‐surface waters and shoaling of deep isotherms above the sill during winter to spring. Renewal of below‐sill waters coincides with the arrival of dense waters at the fjord mouth; warm, salty Atlantic‐origin water cascades into fjord basins from winter to midsummer. We then use Seaglider observations at Davis Strait, along with reanalysis of sea ice and wind stress in Baffin Bay, to explore the role of the West Greenland Current and local air‐sea forcing in driving fjord renewal. These results demonstrate the importance of both remote and local processes in driving renewal of near‐terminus waters, highlighting the need for sustained observations and improved ocean models that resolve the complete slope‐trough‐fjord‐ice system.
Potential Impacts of Sahara Dust Aerosol on Rainfall Vertical Structure Over the Atlantic Ocean as Identified From EOF Analysis
Authors: Dong Xue , Li Rui , Wang Yu , Fu Yunfei , Zhao Chun
Published: August 2018

The current study investigates the potential impacts of Sahara dust on rainfall vertical structure over the Atlantic Ocean by employing multisensor satellite observations. The variabilities in rainfall vertical structure are decomposed by empirical orthogonal function (EOF) analysis. For a given near surface rain rate, the mean storm height of stratiform rain under dust‐laden condition is significantly higher than that under the dust‐free condition. The stratiform rain rate at the layers well above the freezing level is substantially enhanced under dust‐laden condition. Those changes may result from dynamic and thermodynamic effect of Sahara Air Layer effect and/or the effect that dust aerosol acting as additional ice nuclei. For convective rain, there is no significant difference in the leading three normalized EOF modes between the dust‐laden and dust‐free sectors, implying that dust effect, if exists, is not strong enough to cause evident changes in convective rainfall profiles. For stratiform rain, the EOF1 shows no signals of dust effect either. However, significant difference is found in the EOF2 and EOF3 modes between dust‐laden and dust‐free conditions. The normalized EOF2 and EOF3 under dust‐laden condition both represent enhanced rain rate at the upper layer well above the freezing level, where heterogeneous ice nucleation prevails. The statistical study shows consistent results with the case study, except that the aerosol‐related changes in stratiform rainfall vertical structure is isolated in the EOF3 only. This study suggests that EOF analysis is a promising way for isolating the potential and relatively weak aerosol effects on precipitation from the strong dynamic effects.
Circulation‐Conditioned Wintertime Temperature Bias in EURO‐CORDEX Regional Climate Models Over Central Europe
Authors: Lhotka Ondřej , Kyselý Jan
Published: August 2018

We analyze circulation‐conditioned wintertime temperature biases in regional climate models (RCMs) over Central Europe and link them to simulation of cold days. Daily minimum and maximum temperatures from the European Coordinated Regional Climate Downscaling Experiment RCMs are evaluated against reference data from the E‐OBS gridded data set. Flow direction is analyzed through u‐ and v‐wind components at the 850‐hPa pressure level taken from the ERA‐Interim reanalysis. Cloud cover and snow‐area fraction from the same reanalysis are used to associate the temperature biases with physical mechanisms. Distribution of flow directions during cold days is evaluated using efficiency coefficients, calculated as ratios of the relative abundance of flow directions during cold days and their wintertime climatology. RCMs driven by the reanalysis have both positive and negative minimum temperature biases, ranging from +0.7 to −2.7 °C. By contrast, all reanalysis‐driven RCMs have negative maximum temperature biases, especially during northerly and westerly advection, which is probably related to overestimated cloud cover. The too‐cold westerly and northerly flows are associated with an overestimated number of cold days and relatively high values of efficiency coefficients under these directions. Efficiency coefficients are simulated better under southeasterly advection, during which the temperature bias tends to be the lowest. The results suggest that simulated cold events should be analyzed and interpreted with caution, since they may develop also under zonal flow in some models, which contradicts observations.
Characteristics of Lightning Flashes Associated With the Charge Layer Near the 0 °C Isotherm in the Stratiform Region of Mesoscale onvective Systems
Authors: Wang Fei , Liu Hengyi , Dong Wansheng , Zhang Yijun , Meng Qing
Published: August 2018

Data from an S‐band Doppler radar system and a three‐dimensional very high frequency (VHF) radiation source location system in Chongqing, China, were combined to analyze the characteristics of stratiform lightning flashes associated with the charge layer near the 0 °C isotherm (SL0s) in 10 mesoscale convective systems during the summers of 2014–2015. Most of the SL0 events occurred during the dissipating stage of two thunderstorms. The bright band was found to have a very close relationship with the initiation of the SL0 events. The noninductive and inductive charging mechanisms associated with the process of melting ice particles were inferred to contribute to the charge of the bright band area. The reflectivity at the first located VHF radiation source (FirstS) of the SL0s was always weaker than that in the reflectivity core within the lightning area. The stronger the reflectivity core, the greater the difference between the reflectivity and the reflectivity core. The SL0s generated by the thunderstorms with low SL0 frequency tended to have weaker reflectivity at the FirstS but a stronger reflectivity core in the lightning area than that of the thunderstorms with high SL0 frequency. In the storms with low SL0 frequency, SL0s occurred only when the initiation height of the stratiform lightning flashes decreased gradually toward the height range of the SL0s; but in one storm with high SL0 frequency, the SL0s were generated simultaneously with the stratiform lightning flashes initiated at a high level. It gives a clue that the melting charging mechanisms may enhance the charge density of the bright band area.
Joint Transmitter Selection and Resource Management Strategy Based on Low Probability of Intercept Optimization for Distributed Radar Networks
Authors: Shi C. G. , Wang F. , Salous S. , Zhou J. J.
Published: August 2018

In this paper, a joint transmitter selection and resource management (JTSRM) strategy based on low probability of intercept (LPI) is proposed for target tracking in distributed radar network system. The basis of the JTSRM strategy is to utilize the optimization technique to control transmitting resources of radar networks in order to improve the LPI performance while guaranteeing a specified target‐tracking accuracy. The weighted intercept probability and transmit power of radar networks is defined and subsequently employed as the optimization criterion for the JTSRM strategy. The resulting optimization problem is to minimize the LPI performance criterion of radar networks by optimizing the revisit interval, dwell time, transmitter selection, and transmit power subject to a desired target‐tracking performance and some resource constraints. An efficient and fast three‐step solution technique is also developed to solve this problem. The presented mechanism implements the optimal working parameters based on the feedback information in the tracking recursion cycle in order to improve the LPI performance for radar networks. Numerical simulations are provided to verify the superior performance of the proposed JTSRM strategy.
Detection of Low‐Frequency Continuum Radiation
Authors: Füllekrug Martin , Koh Kuang , Liu Zhongjian , Mezentsev Andrew
Published: August 2018

The electromagnetic spectrum at low frequencies from ∼3 to 300 kHz is dominated by impulses from lightning discharges and anthropogenic radio transmissions used for communication. Electromagnetic waves generated in near‐Earth space exhibit generally smaller amplitudes that are attenuated when travelling through the ionosphere before they can be observed at high and midlatitudes. Electromagnetic waves with yet smaller amplitudes contribute to the overall electromagnetic energy trapped within the Earth‐ionosphere cavity. At this point, the electromagnetic waves from all possible sources blend into an unstructured continuum radiation near the instrumental noise floor, which is often considered to be a fundamental limit to scientific discovery. As a result, the sources of continuum radiation have been little studied and are essentially unknown. Here we show how low‐frequency continuum radiation is detected and discriminated against known radio sources and instrumental noise by use of rigorous criteria inferred from novel precision measurements with an array of radio receivers. In particular, it is found that coherent continuum radiation from intermittent radio transmitters exhibits electric field strengths 0.5–0.7 μV/m, which are almost 2 orders of magnitude smaller when compared to the noise floor of the radio receivers ∼25 μV/m. Another part of the continuum radiation is found at local zenith above the array when it is caused by random instrumental noise. The results exemplify the possibility to extract sources from continuum radiation to study their origin and physical properties, which can contribute to an improved understanding of the impact of space weather and solar variability on the Earth's upper atmosphere.
CircularRNA_104670 plays a critical role in intervertebral disc degeneration by functioning as a ceRNA
Authors: Song Jian , Wang Hong-Li , Song Ke-Han , Ding Zhi-Wen , Wang Hai-Lian , Ma Xiao-Sheng , Lu Fei-Zhou , Xia Xin-Lei , Wang Ying-Wei , Fei-Zou  , Jiang Jian-Yuan
Published: August 2018

This study was carried out to explore the roles of circular RNAs (circRNAs) in nucleus pulposus (NP) tissues in intervertebral disc degeneration (IDD). Differentially expressed circRNAs in IDD and normal NP tissues were identified based on the results of microarray analysis. Bioinformatics techniques were employed to predict the direct interactions of selected circRNAs, microRNAs (miR), and mRNAs. CircRNA_104670 was selected as the target circRNA due to its large multiplier expression in IDD tissues. After luciferase reporter and EGFP/RFP reporter assays, we confirmed that circRNA_104670 directly bound to miR-17-3p, while MMP-2 was the direct target of miR-17-3p. The receiver-operating characteristic (ROC) curve showed that circRNA_104670 and miR-17-3p had good diagnostic significance for IDD (AUC circRNA_104670 = 0.96; AUC miRNA-17-3p = 0.91). A significant correlation was detected between the Pfirrmann grade and expression of circRNA_104670 (r = 0.63; p = 0.00) and miR-17-3p (r = −0.62; p = 0.00). Flow-cytometric analysis and the MTT assay showed that interfering with circRNA_104670 using small interfering RNA (siRNA) inhibited NP cell apoptosis (p < 0.01), and this inhibition was reduced by interfering with miR-17-3p. Interfering with circRNA_104670 suppressed MMP-2 expression and increased extracellular matrix (ECM) formation, which were also reduced by interfering with miR-17-3p. Finally, an MRI evaluation showed that circRNA_104670 inhibition mice had a lower IDD grade compared with control mice (p < 0.01), whereas circRNA_104670 and miRNA-17-3p inhibition mice had a higher IDD grade compared with circRNA_104670 inhibition mice (p < 0.05). CircRNA_104670 is highly expressed in the NP tissues of IDD and acts as a ceRNA during NP degradation.
Hybrid graphene metasurfaces for high-speed mid-infrared light modulation and single-pixel imaging
Authors: Zeng Beibei , Huang Zhiqin , Singh Akhilesh , Yao Yu , Azad Abul K. , Mohite Aditya D. , Taylor Antoinette J. , Smith David R. , Chen Hou-Tong
Published: August 2018

During the past decades, major advances have been made in both the generation and detection of infrared light; however, its efficient wavefront manipulation and information processing still encounter great challenges. Efficient and fast optoelectronic modulators and spatial light modulators are required for mid-infrared imaging, sensing, security screening, communication and navigation, to name a few. However, their development remains elusive, and prevailing methods reported so far have suffered from drawbacks that significantly limit their practical applications. In this study, by leveraging graphene and metasurfaces, we demonstrate a high-performance free-space mid-infrared modulator operating at gigahertz speeds, low gate voltage and room temperature. We further pixelate the hybrid graphene metasurface to form a prototype spatial light modulator for high frame rate single-pixel imaging, suggesting orders of magnitude improvement over conventional liquid crystal or micromirror-based spatial light modulators. This work opens up the possibility of exploring wavefront engineering for infrared technologies for which fast temporal and spatial modulations are indispensable.
CiRS-7 promotes growth and metastasis of esophageal squamous cell carcinoma via regulation of miR-7/HOXB13
Authors: Li Rui-chao , Ke Shun , Meng Fan-kai , Lu Jun , Zou Xiao-jing , He Zhi-gang , Wang Weng-feng , Fang Ming-hao
Published: August 2018

The circular RNA ciRS-7 has been reported to be involved in the pathogenesis of various tumors, including gastric and colorectal cancer. However, the role of ciRS-7 in esophageal squamous cell carcinoma (ESCC) remains unsolved. In this study, we found that the ciRS-7 expression was significantly upregulated in ESCC cancer tissues compared with matched normal tissues and associated with poor patient survival. Overexpression of ciRS-7 abrogated the tumor-suppressive roles of miR-7 including cell proliferation, migration and invasion in vitro as well as tumor growth and lung metastasis in vivo. Mechanistically, ciRS-7 functioned as the sponge of miR-7 and reactivated its downstream HOXB13-mediated NF-κB/p65 pathway. Conclusively, our findings demonstrate how ciRS-7 induces malignant progression of ESCC and that ciRS-7 may act as a novel prognostic marker and therapeutic target for this lethal disease.
Cbl-b deficiency provides protection against UVB-induced skin damage by modulating inflammatory gene signature
Authors: Singh Tej Pratap , Vieyra-Garcia Pablo A. , Wagner Karin , Penninger Josef , Wolf Peter
Published: August 2018

Exposure of skin to ultraviolet (UV) radiation induces DNA damage, inflammation, and immune suppression that ultimately lead to skin cancer. However, some of the pathways that regulate these events are poorly understood. We exposed mice to UVB to study its early effects in the absence of Cbl-b, a known suppressor of antitumor immune response in the skin. Cbl-b−/− mice were protected from UV-induced cell damage as shown by the lower number of cyclobutane pyrimidine dimers and sunburn cells in exposed skin compared to wild-type mice. Microarray data revealed that deficiency of Cbl-b resulted in differential expression of genes involved in apoptosis evasion, tumor suppression and cell survival in UV-exposed skin. After UVB, Cbl-b−/− mice upregulated gene expression pattern associated with regulation of epidermal cell proliferation linked to Wnt signaling mediators and enzymes that relate to cell removal and tissue remodeling like MMP12. Additionally, the skin of Cbl-b−/− mice was protected from chronic inflammatory responses and epidermal hyperplasia in a 4-weeks UVB treatment protocol. Overall, our results suggest a novel role for Cbl-b in regulating inflammation and physiologic clearance of damaged cells in response to UVB by modulating inflammatory gene signature.
Mesenchymal stem cells ameliorate hyperglycemia-induced endothelial injury through modulation of mitophagy
Authors: Zhu Wuzheng , Yuan Yujia , Liao Guangneng , Li Lan , Liu Jingping , Chen Younan , Zhang Jie , Cheng Jingqiu , Lu Yanrong
Published: August 2018

Mitochondrial dysfunction and excessive mitochondrial reactive oxygen species (ROS) are fundamental contributors to endothelial injury in diabetic states. Mesenchymal stem cells (MSCs) have exhibited an extraordinary cytoprotective effect that extends to the modulation of mitochondrial homeostasis. However, the underlying mechanisms have not been clearly defined. Emerging evidence has suggested that mitophagy could counteract mitochondrial-derived oxidative stress through the selective elimination of impaired or dysfunctional mitochondria. Therefore, we investigated whether MSCs could ameliorate high-glucose-induced endothelial injury through the modulation of mitophagy. We observed that exposure of human umbilical vein endothelial cells (HUVECs) to high glucose triggers mitochondrial impairment with excessive mitochondrial fragmentation and ROS generation, loss of membrane potential and reduced ATP production. Furthermore, mitophagy was blunted upon high glucose insult, which accelerated dysfunctional mitochondrial accumulation, initiating the mitochondrial apoptotic pathway and, eventually, endothelial dysfunction. MSCs treatment notably attenuated these perturbations accompanied by an enhancement of Pink1 and Parkin expression, whereas these beneficial effects of MSCs were abolished when either Pink1 or Parkin was knocked down. In aortas of diabetic rats, defective mitophagy was observed, which coincided with marked mitochondrial dysfunction. Ultrastructurally, RAECs from diabetic rats revealed a significant reduction in autophagic vacuoles and a marked increase in fragmented mitochondria. Importantly, the infusion of MSCs restored Pink1/Parkin-mediated mitophagy, ameliorated mitochondrial dysfunction and attenuated apoptosis in endothelial cells in diabetic rats. These results suggest that MSCs may protect endothelial cells from hyperglycemia-induced injury by ameliorating mitochondrial dysfunction via Pink1/Parkin –mediated mitophagy
Nano-sized Al2O3 particle-induced autophagy reduces osteolysis in aseptic loosening of total hip arthroplasty by negative feedback regulation of RANKL expression in fibroblasts
Authors: Li De , Wang Chenglong , Li Zhuokai , Wang Hui , He Jiye , Zhu Junfeng , Zhang Yuehui , Shen Chao , Xiao Fei , Gao Yuan , Zhang Xiang , Li Yang , Wang Peng , Peng Jianping , Cai Guiquan , Zuo Bin , Yang Yuehua , Shen Yun , Song Weidong , Zhang Xiaoling , Shen Lei , Chen Xiaodong
Published: August 2018

Aseptic loosening is mainly caused by wear debris generated by friction that can increase the expression of receptor activation of nuclear factor (NF)-κB (RANKL). RANKL has been shown to support the differentiation and maturation of osteoclasts. Although autophagy is a key metabolic pathway for maintaining the metabolic homeostasis of cells, no study has determined whether autophagy induced by Al2O3 particles is involved in the pathogenesis of aseptic loosening. The aim of this study was to evaluate RANKL levels in patients experiencing aseptic loosening after total hip arthroplasty (THA) and hip osteoarthritis (hOA) and to consequently clarify the relationship between RANKL and LC3II expression. We determined the levels of RANKL and autophagy in fibroblasts treated with Al2O3 particles in vitro while using shBECN-1 interference lentivirus vectors to block the autophagy pathway and BECN-1 overexpression lentivirus vectors to promote autophagy. We established a novel rat model of femoral head replacement and analyzed the effects of Al2O3 particles on autophagy levels and RANKL expression in synovial tissues in vivo. The RANKL levels in the revision total hip arthroplasty (rTHA) group were higher than those in the hOA group. In patients with rTHA with a ceramic interface, LC3II expression was high, whereas RANKL expression was low. The in vitro results showed that Al2O3 particles promoted fibroblast autophagy in a time- and dose-dependent manner and that RANKL expression was negatively correlated with autophagy. The in vivo results further confirmed these findings. Al2O3 particles induced fibroblast autophagy, which reduced RANKL expression. Decreasing the autophagy level promoted osteolysis and aseptic prosthetic loosening, whereas increasing the autophagy level reversed this trend.