bluuebunny/crossref_metadata_2025 huggingface dataset:
Thermal performance comparison of different sun tracking configurations
Authors: Achkari O. , El Fadar A.
Published: February 2020

Parabolic trough collector (PTC) is one of the most widespread solar concentration technologies and represents the biggest share of the CSP market; it is currently used in various applications, such as electricity generation, heat production for industrial processes, water desalination in arid regions and industrial cooling. The current paper provides a synopsis of the commonly used sun trackers and investigates the impact of various sun tracking modes on thermal performance of a parabolic trough collector. Two sun-tracking configurations, full automatic and semi-automatic, and a stationary one have numerically been investigated. The simulation results have shown that, under the system conditions (design, operating and weather), the PTC's performance depends strongly on the kind of sun tracking technique and on how this technique is exploited. Furthermore, the current study has proven that there are some optimal semi-automatic configurations that are more efficient than one-axis sun tracking systems. The comparison of the mathematical model used in this paper with the thermal profile of some experimental data available in the literature has shown a good agreement with a remarkably low relative error (2.93%).
Optimization of machining parameters in turning of Inconel 718 Nickel-base super alloy
Authors: Frifita Wassila , Ben Salem Sahbi , Haddad Abdelkrim , Yallese Mohamed Athmane
Published: February 2020

The high hardness and low thermal diffusivity along with the tremendous strength at high temperatures has rendered the nickel-base super alloys Inconel 718 one of the most difficult to cut material. It possesses a wide range of applications including aerospace as well as chemical and petrochemical industries, and is primarily used in the manufacture of aircraft gas turbines, space vehicles, nuclear power systems, and medical equipment. The present study is mainly focused on the cutting parameters optimization that leads to minimum surface roughness, cutting force and power, specific energy and maximum productivity during the turning of the molded Inconel 718 using a carbide cutting tool. The analysis of variance (ANOVA) method is applied to identify the cutting parameters that most influence the response criteria, and the response surface methodology (RSM) along with the desirability function (DF) approaches are further used to develop the prediction model that addresses the optimization procedure. The different parameters are considered one at a time in order to evaluate the sensitivity of the response (OFAT). This procedure led to identify the nose radius (rε), the feed rate (f), the depth of cut (ap) and the cutting speed (Vc) as the most significant factors on both the surface roughness and the cutting forces. Furthermore, the product (f × ap) and the cutting speed (Vc) were found to be the most dominant factors on the specific energy.
Orbitale Entzündung: aktuelle Trends
Authors: Pitz Susanne
Published: February 2020

In das Feld der idiopathischen orbitalen Entzündung ist „Bewegung“ gekommen: Mit der Erstbeschreibung der IgG4-assoziierten Erkrankung vor etwa 10 Jahren ist die Gruppe der idiopathischen Läsionen um etwa die Hälfte geschrumpft. Die Differenzialdiagnose ist deutlich anspruchsvoller geworden, weil die klinische und bildgebende Überlappung dieser Krankheitsbilder erheblich ist. Der vorliegende Artikel gibt einen Überblick über dieses im Umbruch befindliche Feld.
Lösungsmöglichkeiten bei fehlgeschlagenen Osteosynthesen an der Hand
Authors: Langer Martin F. , Raschke Michael J.
Published: February 2020

Für Revisionsoperationen bei Osteosynthesen der Hand braucht der Chirurg viel Kreativität, Erfahrung und technisches Geschick. Die Osteosynthesen im karpalen Bereich benötigen Stabilität und Ruhe, während die Osteosynthesen an den Fingern Stabilität für eine frühzeitige Beübung benötigen. Die Stabilität an den Fingern muss so erreicht werden, dass die Weichteile nicht kompromittiert werden. Hier werden einige der Lösungsmöglichkeiten im karpalen, metakarpalen und phalangealen Bereich vorgestellt.
Performance of two Methods for Cardiac MRI Edema Mapping: Dual-Contrast Fast Spin-Echo and T2 Prepared Balanced Steady State Free Precession
Authors: Krumm Patrick , Martirosian Petros , Rath Dominik , Gawaz Meinrad , Nikolaou Konstantin , Klumpp Bernhard Daniel , Hornung Andreas , Kramer Ulrich , Schick Fritz , Geisler Tobias , Zitzelsberger Tanja
Published: February 2020

Purpose To compare true positive and false negative results of myocardial edema mapping in two methods. Myocardial edema may be difficult to detect on cardiac MRI.

Materials and Methods 76 patients (age 59 ± 11 years, 15 female) with acute myocardial infarction (MI) and 10 healthy volunteers were prospectively included in this single-center study. 1.5 T cardiac MRI was performed in patients 2.5 days after revascularization (median) for edema mapping: Steady State Free Precession (SSFP) mapping sequence with T2-preparation pulses (T2prep); and dual-contrast Fast Spin-Echo (dcFSE) signal decay edema mapping. Late gadolinium enhancement (LGE) was used as the reference for expected edema in acute MI.

Results 311 myocardial segments in patients were acutely infarcted with mean T2 73 ms for T2prep SSFP vs. 87 ms for dcFSE edema mapping. In healthy volunteers the mean T2 was 56 ms for T2prep SSFP vs. 50 ms for dcFSE edema mapping. Receiver operating characteristic (ROC) curve for T2prep SSFP show area under the curve (AUC) 0.962, p < 0.0001, Youden index J 0.8266, associated criterion > 60 ms, sensitivity 94 %, specificity 89 %. dcFSE ROC AUC 0.979, p < 0.0001, J 0.9219, associated criterion > 64 ms, sensitivity 93 %, specificity 99 %.

Conclusion Both edema mapping methods indicate high-grade edema with high sensitivity. Nevertheless, edema in acute infarction may be focally underestimated in both mapping methods.

Key Points: 

Citation Format
Imaging in Obstructive Jaundice: What a Radiologist Needs to Know before Doing a Percutaneous Transhepatic Biliary Drainage
Authors: Gupta Pankaj , Gupta Jyoti , Kumar-M Praveen
Published: February 2020

Percutaneous transhepatic biliary drainage (PTBD) is one of the commonly performed biliary interventions. In patients with obstructive jaundice, PTBD may be a lifesaving emergency procedure or may serve as an alternative intervention in patients who fail to undergo endoscopic drainage or those who are too sick to be considered for endoscopic drainage. The key factor in technical and clinical success of PTBD is a thorough preprocedure imaging evaluation. In this review, we highlight the imaging aspects that should be evaluated and reported by a radiologist when evaluating a patient planned for biliary drainage.
Periorbital Inner Canthal Arteriovenous Malformations: Percutaneous Glue Embolization in Three Cases
Authors: Nagarajan Krishnan , Babu Arul A. S. , Sabarish Sekar , Elango Swamiappan , Babu Krishna Ramesh , Saxena Sunil Kumar
Published: February 2020

Inner canthal or palpebral arteriovenous malformations (AVMs) are uncommon and difficult lesions to treat if they are of high-flow type. Though they may present with mainly cosmetic reasons, they derive feeders from the ophthalmic artery and are associated with dangerous anastomoses. Percutaneous liquid embolic agent has been used to treat various head and neck vascular malformations and tumors and, if done in meticulous attention to detail, can offer cure or control before surgical excision. We report three adults who presented with medial canthal swelling and on imaging diagnosed to have high-flow AVMs. They underwent percutaneous n-butyl cyanoacrylate (glue) embolization and subsequently operated to excise the embolized malformation without any blood loss or complications.
Cerebral Proliferative Angiopathy: An Uncommon and Misdiagnosed Entity
Authors: Tiwari Sarbesh , Garg Pawan K. , Khera Pushpinder S. , Babu Santhosh , Sureka Binit , Yadav Taruna
Published: February 2020

Cerebral proliferative angiopathy (CPA), previously known as diffuse nidus-type arteriovenous malformation (AVM) is an entity distinct from cerebral AVM, characterized by multiple small arterial feeders, large-size nidus involving entire lobe or hemisphere, and no early draining veins with normal brain parenchyma interspersed between the abnormal vessels. It is usually seen in younger age group and is more common in females. We hereby report a case of diffuse cerebral proliferative angiopathy in a 29-year-old man who presented with intracranial hemorrhage. It is important to recognize this entity to avoid aggressive treatment, thus preventing permanent damage to the normal intermingled brain tissue.
Comparative Fluoride Release and Antimicrobial Analysis of Commercial and Experimental Bioactive Glass/Nano-Oxide-Based Dentifrices
Authors: Gul Hashmat , Nayyer Maleeha , Gilani Mehreen , Aman Nadia , Azad Azad Ali , Shah Asma Tufail , Chaudhry Aqif Anwar , Kaleem Muhammad , Khan Abdul Samad
Published: February 2020

Objectives The objectives were to measure fluoride release and assess the antimicrobial behavior of fluoride-doped nano bioactive glass (F-nBG) and nano zinc oxide (ZnO)-enriched novel dentifrices.

Materials and Methods Experimental dentifrices were synthesized by incorporating ZnO nanoparticles and F-nBG (1.5 wt% and 4 wt%) as active ingredients. The fluoride release behavior of suspensions and elutes of samples were analyzed by ion selective electrode. Antimicrobial activity and minimum bactericidal concentration against Streptococcus mutans and Lactobacillus casei were evaluated. Microbial stability against contamination was also assessed by a challenge test.

Results The fluoride release behavior of experimental dentifrices was higher than that of commercial dentifrices and was dependent on filler loading. The fluoride release was more from suspensions than elutes. Zones of inhibition (ZOIs) and minimum bactericidal concentration values for novel dentifrices showed direct proportionality with filler loading, and effectiveness was exhibited against both strains. Experimental dentifrices exhibited effective antibacterial potential, which could possibly be due to release of sufficient fluoride and zinc ions in aqueous media from F-nBG and ZnO present in their formulations.

Conclusion Combination of F-nBG and ZnO may provide a multi-benefit approach for simultaneously treating early white spot lesions, reducing bacterial growth, and providing core plaque control.
Higher Component Malposition Rates with Patient-Specific Cruciate Retaining TKA than Contemporary Posterior Stabilized TKA
Authors: Kumar Prakrit , Elfrink Jacob , Daniels James P. , Aggarwal Ajay , Keeney James A.
Published: February 2020

Customized individually manufactured total knee arthroplasty (CIM-TKA) was developed to improve kinematic total knee arthroplasty (TKA) performance. Component placement accuracy may influence the success of CIM-TKA designs. We performed this study to compare radiographic component alignment and revision rates of a cruciate retaining (CR) CIM-TKA and a contemporary posterior stabilized TKA (PS-TKA). After obtaining Institutional Review Board approval, we identified 94 CR CIM-TKAs (76 patients) and 91 PS-TKAs (82 patients) performed between July 1, 2013 and December 31, 2014 with a minimum 2-year follow-up (mean 41.1 months, range 24–59 months). We performed a retrospective electronic medical record review to identify patient demographic characteristics and revision procedures performed. Postoperative plain radiographs were reviewed to assess component alignment including cruciate ligament imbalance, femoral overhang, and femoral notching. Demographic characteristics, component malalignment, and revision surgery rates were assessed using a student's t-test or two-tailed Fisher's exact test, with a p-value < 0.05 designating significance. Technical errors were more commonly identified with CR CIM-TKA (29.8 vs. 9.9%, p < 0.001), including higher rates of tibiofemoral instability (13.8 vs. 1.1%, p < 0.01), femoral notching (12.8 vs. 3.3%, p = 0.03), and patellofemoral malalignment (20.2 vs. 7.7%, p = 0.02). CR CIM-TKA had more frequent coronal plane malposition (26.6 vs. 9.9%, p < 0.01) or sagittal plane reconstruction > 3 degrees outside of an optimized range (20.2 vs. 9.9%, p = 0.06). Aseptic revisions occurred more frequently with the CR CIM-TKA design (9.6 vs. 3.3%, p = 0.13). Demographic characteristics were not significantly different between the treatment groups. CR CIM-TKA may improve kinematic performance for patients undergoing knee replacement surgery. However, our study observations suggest that careful attention to surgical technique is important for optimizing implant survivorship with the CR CIM-TKA design. Additional study is needed to determine whether higher revision rates identified during this study are related to patient selection, surgical technique, or implant design.
Electron self-injection threshold for the tandem-pulse laser wakefield accelerator
Authors: Chitgar Zahra M. , Gibbon Paul , Böker Jürgen , Lehrach Andreas , Büscher Markus
Published: February 2020

A controllable injection scheme is key to producing high quality laser-driven electron beams and x rays. Self-injection is the most straightforward scheme leading to high current and peak energies but is susceptible to variations in laser parameters and target characteristics. In this work, improved control of electron self-injection in the nonlinear cavity regime using two laser-pulses propagating in tandem is investigated. In particular, the advantages of the tandem-pulse scheme in terms of injection threshold, electron energy, and beam properties in a regime relevant to betatron radiation are demonstrated. Moreover, it is shown that the laser power threshold for electron self-injection can be reduced by up to a factor of two compared to the standard, single-pulse wakefield scheme.
Steering an intense relativistic electron beam in a linear induction accelerator
Authors: Ekdahl Carl , Allison P. , Coleman J. E. , Kaupilla T. , McCuistian B. T. , Moir D. C. , Schulze M.
Published: February 2020

The best electron beam transport through a linear induction accelerator (LIA) is achieved when the beam is well centered on the magnetic axis of the focusing solenoids. Since the beam may be injected offset from, or at an angle to, the centerline, dipole magnets are usually provided as a means to steer the beam and center it. Steering may be accomplished by trial and error, but this is very time consuming, especially for accelerators with a low repetition rate for beam position measurements and dipole adjustments. This article presents a steering method requiring a minimal number of measurements and adjustments to position the beam at any desired location, including positioning on the centerline.
Interactions between interstitial oxygen and substitutional niobium atoms in Ti–Nb–O BCC alloys: First-principles calculations
Authors: Liu Chenguang , Yu Liming , Liu Yongchang , Ma Zongqing , Li Huijun , Li Chong , Liu Chenxi
Published: February 2020

In this paper, the interactions between interstitial oxygen atoms and substitutional atoms in Ti–Nb–O alloys were investigated by first-principles calculations based on the density functional theory. The binding energies and formation energies of oxygen atoms sited were calculated in various interstices with different geometries, element species, and atomic arrangements. The calculation results showed that there was a strong repulsive binding energy between the interstitial oxygen and the substitutional niobium atoms. On this basis, the energetically favored sites and the distribution of interstitial oxygen atoms in Ti–Nb–O alloys were discussed and demonstrated by an electron energy loss spectroscopy method. Furthermore, the diffusion activation energies of interstitial oxygen atoms based on the formation energy results were presented, and the diffusion behaviors of interstitial oxygen atoms in Ti–Nb–O alloys were also discussed.
A modular ultra-high vacuum millikelvin scanning tunneling microscope
Authors: Wong Dillon , Jeon Sangjun , Nuckolls Kevin P. , Oh Myungchul , Kingsley Simon C. J. , Yazdani Ali
Published: February 2020

We describe the design, construction, and performance of an ultra-high vacuum (UHV) scanning tunneling microscope (STM) capable of imaging at dilution-refrigerator temperatures and equipped with a vector magnet. The primary objective of our design is to achieve a high level of modularity by partitioning the STM system into a set of easily separable, interchangeable components. This naturally segregates the UHV needs of STM instrumentation from the typically non-UHV construction of a dilution refrigerator, facilitating the usage of non-UHV materials while maintaining a fully bakeable UHV chamber that houses the STM. The modular design also permits speedy removal of the microscope head from the rest of the system, allowing for repairs, modifications, and even replacement of the entire microscope head to be made at any time without warming the cryostat or compromising the vacuum. Without using cryogenic filters, we measured an electron temperature of 184 mK on a superconducting Al(100) single crystal.
Interfacial Dzyaloshinskii-Moriya interaction between ferromagnetic insulator and heavy metal
Authors: Xia Siyu , Zhang Sheng , Luan Zhongzhi , Zhou Lifan , Liang Jinghua , Liu Gan , Yang Bin , Yang Hongxin , Liu Ronghua , Wu D.
Published: February 2020

Recent demonstration of the interfacial Dzyaloshinskii-Moriya interaction (DMI) between a heavy metal and a magnetic insulator provides the possibility to manipulate chiral spin textures in the magnetic insulator for the extremely low power consumption devices. However, the origin and strength of the interfacial DMI remain in dispute in this system. We used the electrical transport measurements to determine the DMI strength to be ∼0.040 pJ/m at room temperature in Pt/Tm3Fe5O12 (TmIG) bilayers. The TmIG saturation magnetization and DMI strength exhibit different temperature dependences, which is attributed to the DMI being mainly contributed by Fe ions instead of Tm ions. With a Cu layer inserted between Pt and TmIG, the DMI strength is reduced to ∼0.012 pJ/m and the topological Hall effect vanishes, strongly suggesting that the Pt/TmIG interface has important contribution to the DMI.
Influence of rectilinear vs radial advection on the yield of A + B → C reaction fronts: A comparison
Authors: Brau Fabian , De Wit A.
Published: February 2020

In the presence of advection at a constant flow rate in a rectilinear geometry, the properties of planar A + B → C reaction fronts feature the same temporal scalings as in the pure reaction–diffusion case. In a radial injection geometry where A is injected into B radially at a constant flow rate Q, temporal scalings are conserved, but the related coefficients depend on the injection flow rate Q and on the ratio γ of initial concentrations of the reactants. We show here that this dependence of the front properties on the radial velocity allows us to tune the amount of product obtained in the course of time by varying the flow rate. We compare theoretically the efficiency of the rectilinear and radial geometries by computing the amount of product C generated in the course of time or per volume of reactant injected. We show that a curve γc(Q) can be defined in the parameter space (γ, Q) below which, for similar experimental conditions, the total amount of C is larger in the radial case. In addition, another curve γ*(Q) < γc(Q) can be defined such that for γ < γ*, the total amount of C produced is larger in the radial geometry, even if the production of C per unit area of the contact interface between the two reactants is larger in the rectilinear case. This comes from the fact that the length of the contact zone increases with the radius in the radial case, which allows us to produce in fine more product C for a same injected volume of reactant or in reactors of a same volume than in the rectilinear case. These results pave the way to the geometrical optimization of the properties of chemical fronts.
Thermoelastic equation of state and melting of Mg metal at high pressure and high temperature
Authors: Courac Alexandre , Le Godec Yann , Solozhenko Vladimir L. , Guignot Nicolas , Crichton Wilson A.
Published: February 2020

The p-V-T equation of state of magnesium metal has been measured up to 20 GPa and 1500 K using both multianvil and opposite anvil techniques combined with synchrotron x-ray diffraction. To fit the experimental data, the model of Anderson–Grüneisen has been used with fixed parameter δT. The 300-K bulk modulus of B0 = 32.5(1) GPa and its first pressure derivative, B0′ = 3.73(2), have been obtained by fitting available data up to 20 GPa to the Murnaghan equation of state. Thermal expansion at ambient pressure has been described using second order polynomial with coefficients a = 25(2) × 10−6 K−1 and b = 9.4(4) × 10−9 K−2. The parameter describing simultaneous pressure and temperature impact on the thermal expansion coefficient (and, therefore, volume) is δT = 1.5(5). The good agreement between fitted and experimental isobars has been achieved to relative volumes of 0.75. The Mg melting observed by x-ray diffraction and in situ electrical resistivity measurements confirms previous results and additionally confirms the p-T estimations in the vicinity of melting.
Spin-glass behavior in Co-based antiperovskite compound SnNCo3
Authors: Liu Chaocheng , Tao Xuyingnan , Kan Xucai , Liu Xiansong , Zhang Chenghong , Feng Shuangjiu , Yang Yujie , Lv Qingrong , Hu Jiyu , Shezad Mudssir
Published: February 2020

Spin-glass (SG) behavior is observed in the antiperovskite compound SnNCo3, which is confirmed by the relevant measurements and specific parameters [τ0 = 1.397 × 10−11 s, T0 = 2.705 K, zv = 6.857 for χ′(T)]. The typical relaxation behavior of isothermal remanent magnetization (MIRM) exhibits strong spin frustration in the system. The δM plots illustrate the strong exchange coupling and demagnetizing interaction around the freezing temperature (Tf). Besides, the density functional theory calculations demonstrate that the antiferromagnetic ground has lower energy than that of the ferrimagnetic and ferromagnetic states. Our calculations exhibit that the electrons of Co-3d play a dominant role around the Fermi energy (EF), while Sn-5p and N-2p are mainly distributed from −8 eV to −5 eV and −5 eV to 5 eV, respectively. The interactions of Sn-Co and N-Co disclose the magnetic ground state and bond nature of the compound, which should be an evidential response to the SG behavior in SnNCo3.
Rheology of sodium and zinc ionomers: Effects of neutralization and valency
Authors: Zuliki Muaad , Zhang Shiling , Nyamajaro Kudzanai , Tomkovic Tanja , Hatzikiriakos Savvas G.
Published: February 2020

Using a parallel-plate rheometer equipped with a partitioned plate and the Sentmanat extensional rheometer fixture, a full rheological characterization of several commercial ionomers (sodium and zinc) and their corresponding parent copolymers has been carried out. Particular emphasis has been placed on the distribution of the relaxation times to identify the characteristic times, such as reptation, Rouse, and lifetime of associations that are associated with entanglements, ionic and hydrogen bonding associations. As such, scaling laws have been used to calculate the order of magnitude of these characteristic times that are important parameters to gain a better understanding of their rheological behavior. To study the effects of ionic reversible associations, the commercial ionomers were completely un-neutralized and their rheological behavior was compared directly with their associative counterparts. The rheological comparison included the linear viscoelastic moduli, the damping function, and extensional rheology, demonstrating the significant effects of ionic interactions. Moreover, the rheological properties of sodium and zinc ionomers are also compared addressing the effect of valency of ions (Na+ vs Zn++).
Mechanisms of a Small Membrane-Active Antimicrobial Peptide from Hyla punctata
Authors: Chen Charles H. , Ulmschneider Jakob P. , Ulmschneider Martin B.
Published: February 2020

Thousands of antimicrobial peptides have been observed and studied in the past decades; however, their membrane-active mechanisms are ambiguous due to their dynamic structure in the cell membrane. Here, we applied both molecular dynamics (MD) simulations and biophysical experiments to study the small membrane-active antimicrobial peptide Hylaseptin P1 (HSP1), which has significant selectivity towards anionic 1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-(1′-rac-glycerol) (POPG) and bacterial model membranes. HSP1 does not bind and fold onto human red blood cell model membranes, and it only binds, but does not fold, in zwitterionic 1-palmitoyl-2-oleoyl-glycero-3-phosphocholine (POPC) membranes. This suggests that the lipid chemistry and membrane rigidity are key to prevent HSP1 binding onto membranes, and the lipid headgroup charge may further promote peptide folding in the membrane. Our experiment-validated MD simulations suggest a carpet-like model mechanism for HSP1 through peptide binding, folding, aggregation, and assembly. HSP1 is shorter than the membrane thickness; therefore, the folded peptides aggregate on the surface, cross the membrane, and the oligomeric structure is supported by several surface-bound peptides in both bilayer leaflets.
Nomenclature survey of the genus Amaranthus (Amaranthaceae). 6. Names linked to the Australian flora
Authors: Iamonico Duilio , Palmer Jo
Published: February 2020

In this paper, nomenclatural issues concerning nine Amaranthus taxa in the Australian flora are clarified. Lectotypes are designated for names of three currently accepted species (A. interruptus R.Br., A. rhombeus R.Br. and A. undulatus R.Br.) and two names now being considered to be taxonomic synonyms (A. lineatus R.Br. and A. macrocarpus var. pallidus Benth.). The earlier ‘holotype’ citations for the taxonomic synonym A. incurvatus Timeroy ex Gren. & Godr. and the currently accepted species A. quitensis Kunth are here considered effective lectotypifications. The holotype material for the nomenclatural synonym A. mitchellii var. grandiflorus J.M.Black is clarified. A neotype is designated for A. pallidiflorus var. viridiflorus Thell. (now considered to be a taxonomic synonym).
Standing dead trees contribute significantly to carbon budgets in Australian savannas
Authors: Cook Garry D. , Liedloff Adam C. , Meyer C. P. (Mick) , Richards Anna E. , Bray Steven G.
Published: February 2020

Previous estimates of greenhouse gas emissions from Australian savanna fires have incorporated on-ground dead wood but ignored standing dead trees. However, research from eucalypt woodlands in southern Queensland has shown that the two pools of dead wood burn at similar rates. New field data from semiarid savannas across northern Australia confirmed that standing dead trees comprise about four times the mass of on-ground dead wood. Further, the proportion of total woody biomass comprising dead wood increases with decreasing fire frequency and a decreasing proportion of late dry season (August to December) fires. This gives scope for increasing the carbon stock in the dead wood pool with a reduced fire frequency. Following a previously published approach to quantify total dead wood loads in savannas, new and previously collected data on tree stand structures were used across the whole savanna zone to quantify dead wood loads in equilibrium with historic fire regimes. New parameters are presented for calculating dead wood dynamics including dead trees in Australia’s savannas.
The significance of the adversative connectives aber, mais, ma (‘but’) as indicators in young
children’s argumentation
Authors: Rocci Andrea , Greco Sara , Schär Rebecca , Convertini Josephine , Perret-Clermont Anne-Nelly , Iannaccone Antonio
Published: February 2020

Adversative connectives have been analyzed as articulating explicit and implicit facets of argumentative moves and
have been thus recognized as potential argumentative indicators. Here we examine adversative connectives Ger.
aber, Fr. mais, It. ma (‘but’) in young children’s speech in the context of
the ArgImp project, a research endeavor seeking to understand in which situations children aged between two and six years engage
in argumentation and how their contributions are structured. Two multilingual corpora have been collected for the project: (1)
everyday family conversations, (2) semi-structured play activities and problem solving in a kindergarten setting. Through the
detailed analysis of a small collection of examples, we consider the indicative potential of adversative connectives for
identifying argumentative episodes in interactions involving young children and for the reconstruction of the inferential
configurations of children’s contributions to these argumentative discussions. The results show that fully fledged argumentative
interpretations of adversatives occur as a possibility in children’s speech, and that adversative connectives can be used
profitably to identify less apparent argumentative confrontations and implicit standpoints in children’s speech.
Implicit argumentation and persuasion
Authors: Lombardi Vallauri Edoardo , Baranzini Laura , Cimmino Doriana , Cominetti Federica , Coppola Claudia , Mannaioli Giorgia
Published: February 2020

The paper provides evidence that linguistic strategies based on the implicit encoding of information are effective
means of deceptive argumentation and manipulation, as they can ease the acceptance of doubtful arguments by distracting
addressees’ attention and by encouraging shallow processing of doubtful contents. The persuasive and manipulative functions of
these rhetorical strategies are observed in commercial and political propaganda. Linguistic implicit strategies are divided into
two main categories: the implicit encoding of content, mainly represented by implicatures and vague expressions, and the implicit
encoding of responsibility, mainly represented by presuppositions and topics. The paper also suggests that the amount of
persuasive implicitness contained in texts can be measured. For this purpose, a measuring model is proposed and applied to some
Italian political speeches. The possible social usefulness of this approach is showed by sketching the operation of a website in
which the measuring model is used to monitor contemporary political speeches.
Grammaticalization of reflexivity in Basque
Authors: Salaberri Iker
Published: February 2020

The purpose of this paper is to provide a detailed overview of the changes undergone by the reflexiveburu-construction in Basque under the light of grammaticalization theory. On the basis of quantitative historical data, the reflexive construction is argued to have undergone changes predicted by the grammaticalization path of reflexive markers: the distinction between regular and reflexive possessive pronouns is lost; anaphoric, non-reflexive uses ofburudisappear; and number agreement between the subject andburuis no longer obligatory. Theburu-construction is furthermore argued to have become more prevalent at the expense of other reflexivization strategies. As opposed to these changes, the reflexive construction seems to have degrammaticalized as well: the number of direct object uses of this construction decreases over time, and it occurs in subject position with more predicates in present-day written Basque than in the historical period. In view of these facts, an argument is made against unidirectional conceptions of grammaticalization. External motivations for these developments, such as the standardization of the language, are also considered.
Seasonal metaphors in Arab journalistic discourse
Authors: Chatti Sami
Published: February 2020

The rhetorical fabric of the recent Arab uprisings resorts to mythology and metaphoricity to elicit an ideologically-biased polarization of the popular revolts. Building on some striking resemblances the Greek myth of Persephone and the journalistic construction of the Arab revolts hold in common, this paper delves into the oblique parallelism that informs the use of seasonal metaphors to serve ideological functions. The analysis of this pragmatic aspect of metaphorical structuring elaborates on findings of a corpus study, focusing on the collocational tendencies of the Arab Spring and Arab Autumn metaphors in Tunisian and Saudi press outlets. Empirical results show that the anti-revolts agenda selects negatively valued collocates to occur with the Arab Autumn metaphor, whereas the pro-revolts ideology recruits positively-valued lexis to mirror the emancipatory journey voiced by the Arab Spring trope. The paper uses a blend of cognitive theories of metaphor with research from a critical metaphor perspective to elucidate the ideologies which motivate and guide the figurative construal of the popular uprisings in Arab journalistic discourse.
Metaphors in communication about pregnancy loss
Authors: Littlemore Jeannette , Turner Sarah
Published: February 2020

Pregnancy loss, encompassing miscarriage, stillbirth and termination for foetal abnormality, can be considered a
particularly intense and unique form of bereavement, which engenders difficult or painful emotions. When people are talking about
such emotions, they have been found to make extensive use of metaphor (Semino, 2011).
In this paper, we use metaphor analysis of a small corpus of interviews with individuals in England who have suffered such losses,
and people who support them, to explore the nature of the bereavement. In particular, we focus on the ways in which metaphor is
used to describe the experience of the loss, the effects that this loss has on people’s conceptions of themselves and their
bodies, and the implications this has for recovery. We identify a number of characteristics that can lead the bereaved to
conceptualise their realities in different ways, which have implications for the grieving process, the ways in which people
respond to their grief, and ultimately their recovery.
Un análisis sociofonético de la aspiración de las oclusivas sordas en el español guatemalteco monolingüe y bilingüe (español-kaqchikel)
Authors: McKinnon Sean
Published: February 2020

El estudio empírico de la sociofonética del español en contacto con otras lenguas ha aumentado en la última década. Siguiendo con esta área de investigación, el presente estudio examina la aspiración de las oclusivas sordas en el español guatemalteco comparando los factores (extra-)lingüísticos que afectan a la variación en las comunidades monolingües y bilingües (español-kaqchikel), mediante el marco teórico de la sociolingüística comparativa (Poplack y Levey 2010). Los resultados demuestran que, en general, el VOT de esta muestra del español guatemalteco es más largo de lo que se ha descubierto para las variedades sin contacto, pero es paralelo al español en contacto con el maya yucateco (Michnowicz y Carpenter 2013). Aunque, mayoritariamente, los factores lingüísticos afectaron a la variación del VOT, el sexo biológico también resultó relevante. Se discutirán tres puntos clave que señalan la posibilidad de contacto lingüístico como causa, pero se necesitan investigaciones futuras para confirmar definitivamente los efectos del contacto.
Las perífrasis modales con deber en el español actual
Authors: Criado de Diego Cecilia , San Mateo Valdehíta Alicia
Published: February 2020

Las Academias de la lengua establecen prescripciones y recomendaciones sobre el uso de las perífrasis verbales con
deber cuyo cumplimiento en el español actual se ha visto cuestionado por algunos lingüistas, como Blas Arroyo (2013) y Gómez Molina (2013),
entre otros. Analizamos, en el Corpus del Español del Siglo XXI, el uso de deber (de) + infinitivo
(n = 3364) para expresar las modalidades epistémica y deóntica, y su posible condicionamiento por factores
lingüísticos, estilísticos y geográficos. Los resultados muestran que la norma académica, ya sea estricta o moderada, es acorde
con la realidad de la lengua únicamente en la expresión de la modalidad deóntica. Asimismo, los usos no recomendados se ven
favorecidos por la oralidad, por algunos tiempos verbales, como el presente de indicativo en la modalidad epistémica y el
condicional simple en la modalidad deóntica, y por la procedencia dialectal de los hablantes.
Ethics, accuracy, and interpreting in social settings
Authors: Gil-Bardají Anna
Published: February 2020

Accuracy tops most of the codes of ethics for public service interpreting. This dominant position is not
accidental, since the lack of truth in the transmission of the message may entail a violation of the users’ and providers’
fundamental right to truth. In Catalonia, where intercultural mediators have taken on the role of interpreters for many years, the
issue of accuracy becomes even more complex due to their dual roles as professional mediators and non-professional interpreters.
Drawing on more than four hours of video recordings and post-task interviews with study participants, this paper analyzes the accuracy
of five intercultural mediators working with Arabic, Spanish, and Catalan when in the role of interpreter.
Effect of annealing temperature on structure-property correlations in Zn2SnO4 nanostructured films for optoelectronics
Authors: Arora Isha , Kumar Praveen
Published: February 2020

In the present work, the effect of annealing temperature on structural, optical and electrical properties for sol gel synthesized Zn2SnO4 nanostructured films has been investigated for their suitability in optoelectronics. These samples were probed by using XRD, UV-Visible spectroscopy, photoluminescence spectroscopy and Hall measurements. The x-ray diffraction study divulges the polycrystalline nature and phase transition from cubic inverse spinal Zn2SnO4 phase to pervoskite ZnSnO3 phase in the synthesized films. The optical transmission of ∼43 %–73 % in the visible region while the optical gap varies from 3.61–3.95 eV has been observed for the annealed films. The defect related emission peaks at 423, 445 and 481 nm has been observed. The lowest electrical resistivity (5.8 × 10–3 Ω cm) and highest figure of merit  (10–3 Ω−1) for the films annealed at 600 °C has been observed. These results are very important for the development of new n-type transparent conductor for various optoelectronic devices.
Effects of frequency on supercapacitor properties of multi walled carbon nanotubes-polypyrrole film prepared by alternating current-electrophoretic deposition method
Authors: Mohd Saini Muhammad Syafiq Adham , Wahab Nor Aimi Abdul , Yusof Azmi Mohamed , Yusoff Mohd Zaki Mohd , Hashim Abd Hakim , Yahya Muhammad Syarifuddin , Zainie Intan Syaffinazzilla
Published: February 2020

An electroactive supercapacitor electrodes have been prepared through deposition of multi walled carbon nanotubes-polypyrrole (MWCNTs-PPy) via alternating current electrophoretic deposition method (AC-EPD). Using safranin (SAF) as co-dispersant, a stable and well-dispersed MWCNTs were obtained and the deposits of MWCNTs-PPy were successfully formed using AC peak to peak voltage of 8 V but at difference frequencies of 0.01 Hz, 4 Hz and 250 Hz. Varying the frequencies of the applied voltage has been found influencing the morphology and electrochemical properties of the deposited films. A more porous and highest deposited mass of 0.021 g was obtained at frequency of 4 Hz, while at 250 Hz the deposited mass reduces to 0.017 g. The lowest deposited mass of 0.015 g was obtained at the lowest frequency (0.01 Hz). In addition, the morphology structure of the composite film at 4 Hz shows that the PPy were well-distributed throughout MWCNTs surface. The XRD result shows the presence of amorphous PPy and graphite-like MWCNTs for all deposited samples. It has been shown that the specific capacitance values for the composites also strongly depends on the frequency of applied voltage. In the case of frequency of 4 Hz, higher values can be found at 76.08 F g−1 which was more than two folds increment from the lowest frequency (0.01 Hz), however at the highest frequency (250 Hz) a specific capacitance values of 65.03 F g−1 have been measured. The AC-EPD provides avenue for depositing nanocomposites film at relatively low apllied voltage however, there have no linear correllations been observed on the morphology and electrochemical properties of the deposited films as the frequencies of applied voltage increases.
Astronomers raise concerns over SpaceX's Starlink
Authors: Cooper Keith
Published: February 2020

The threat from SpaceX’s fledgling satellite constellation, Starlink, could do irreparable damage to the night sky. That is according to astronomers at some of the biggest observatories in the world, who claim that the system is causing havoc with astronomical observations.
Searching for new worlds
Authors: Pool Rebecca
Published: February 2020

After sharing the 2019 Nobel Prize for Physics for the discovery of the first exoplanet, Didier Queloz talks to Rebecca Pool about the future of planetary exploration
A 2020 vision
Authors: Durrani Matin
Published: February 2020

The start of a new decade is always a perfect time for taking stock and looking optimistically to the future. I’m not sure how long my own optimism will last, and for sure there will be plenty of downs as well as ups over the next 10 years.
Transmogrified physics
Authors: Crease Robert P
Published: February 2020

Robert P Crease seeks your input on an entirely new realm of phenomena
The physics of public opinion
Authors: Brazil Rachel
Published: February 2020

Rachel Brazil investigates how physicists are trying to predict the dynamics of shifting opinions using laws that describe the physical world
The secret of the synchronized pendulums
Authors: Ramirez Jonatan Pena , Nijmeijer Henk
Published: February 2020

The fact that pairs of moving pendulums can become synchronized was first observed by the great Dutch scientist Christiaan Huygens back in the 17th century. But as Jonatan Pena Ramirez and Henk Nijmeijer explain, synchronized pendulums still have today’s researchers scratching their heads
We still don't understand physics
Authors: Prescod-Weinstein Chanda
Published: February 2020

Anthony Aguirre's Cosmological Koans: a Journey to the Heart of Physics adapts the idea of a Zen koan, a story meant to provoke a Zen Buddhist practitioner's intellect. Each section provides insight into some aspect of fundamental physics, while also highlighting questions that are left unanswered, because they remain beyond our current understanding.
Agustina Ruiz Dupont: the greatest physicist you've never heard of
Authors: Dacey James
Published: February 2020

Agustina Ruiz Dupont is the fictional physicist at the heart of a recent Spanish-language docufiction film El Enigma Agustina, directed by astrophysicists Manuel Gonzalez and Emilio J Garcia.
Entanglement points to scalable quantum computers
Authors: Cartlidge Edwin
Published: February 2020

A technique for remotely entangling ions of strontium much more accurately and at far higher rates than previously possible has been unveiled by physicists in the UK.
Hydrogen detection using membrane-type surface stress sensor
Authors: Yakabe Taro , Imamura Gaku , Yoshikawa Genki , Kitajima Masahiro , Itakura Akiko N
Published: February 2020

This study shows a possibility of the application of a membrane-type surface stress sensor (MSS) with a Pd film to a hydrogen sensor. It was able to detect hydrogen concentrations from 5 to 40000 ppm in a nitrogen gas mixture. In the case of a conventional sensor using a hydrogen-occluding material, it is necessary to wait for a state of saturation. In contrast, the proposed method can detect hydrogen quickly by the initial rate of hydrogen absorption. The relationship between the initial absorption rate and hydrogen concentration is explained by considering the two-step reaction kinetics of hydrogen absorption into bulk Pd via Langmuir dissociative adsorption on surface.
Remarks on rational points of universal curves
Authors: Watanabe Tatsunari
Published: February 2020

In this note, we will give some remarks on the results in [J. Amer. Math. Soc. 24 (2011), no. 3, pp. 709–769] by Hain. In particular, we consider the universal curves

M

g
,
n
+
1

→

M

g
,
n

{\mathcal {M}}_{g,n+1}\to {\mathcal {M}}_{g,n}

and the sections of their algebraic fundamental groups.
Univalent functions with quasiconformal extensions: Becker’s class and estimates of the third coefficient
Authors: Gumenyuk Pavel , Hotta Ikkei
Published: February 2020

We investigate univalent functions

f
(
z
)
=
z
+

a
2

z
2

+

a
3

z
3

+
…

f(z)=z+a_2z^2+a_3z^3+\ldots

in the unit disk 

D

\mathbb {D}

extendible to

k
k

-q.c.(=quasiconformal) automorphisms of 

C

\mathbb {C}

. In particular, we answer a question on estimation of 

|

a
3

|

|a_3|

raised by Kühnau and Niske [Math. Nachr. 78 (1977), pp. 185–192]. This is one of the results we obtain studying univalent functions that admit q.c.-extensions via a construction, based on Loewner’s parametric representation method, due to Becker [J. Reine Angew. Math. 255 (1972), pp. 23–43]. Another problem we consider is to find the maximal

k
∗

∈
(
0
,
1
]

k_*\in (0,1]

such that every univalent function 

f
f

in 

D

\mathbb {D}

having a

k
k

-q.c. extension to 

C

\mathbb {C}

with

k
>

k
∗

k>k_*

admits also a Becker q.c.-extension, possibly with a larger upper bound for the dilatation. We prove that

k
∗

>
1

/

6

k_*>1/6

. Moreover, we show that in some cases, Becker’s extension turns out to be the optimal one. Namely, given any

k
∈
(
0
,
1
)

k\in (0,1)

, to each finite Blaschke product there corresponds a univalent function

f
f

in 

D

\mathbb {D}

that admits a Becker

k
k

-q.c. extension but no

k
′

k’

-q.c. extensions to 

C

\mathbb {C}

with 

k
′

>
k

k’>k

.
Essential dimension of the moduli stack of polarized K3 surfaces
Authors: Gao Anningzhe
Published: February 2020

We compute the essential dimension of the moduli stack of polarized K3 surfaces of degree

d
d

, for char

p
=
0

p=0

or

p
>
22

p>22

. The main tool we use is the genericity theorem proved in [Ann. of Math. 171 (2010), pp. 533–544].
Galois extensions and a conjecture of Ogg
Authors: Klosin Krzysztof , Papikian Mihran
Published: February 2020

Let

N
=
p
q

N=pq

be a product of two distinct primes. There is an isogeny

J
0

(
N

)

n
e
w

→

J
N

J_0(N)^\mathrm {new}\to J^N

defined over

Q

\mathbf {Q}

between the new quotient

J
0

(
N
)

J_0(N)

and the Jacobian of the Shimura curve attached to indefinite quaternion algebra of discriminant

N
N

. In the case when

p
=
2
,
3
,
5
,
7
,
13

p=2,3,5,7,13

, Ogg made predictions about the kernels of these isogenies. We show that Ogg’s conjecture is false in general. Afterwards, we propose a strategy for proving results toward Ogg’s conjecture in certain situations. Finally, we discuss this strategy in detail for

N
=
5
⋅
13

N=5\cdot 13

.