bluuebunny/crossref_metadata_2025 huggingface dataset:
Onset of oscillatory Rayleigh-Bénard magnetoconvection with rigid horizontal boundaries
Authors: Mondal Hiya , Das Alaka , Kumar Krishna
Published: January 2018

We present the results of linear stability analysis of oscillatory Rayleigh-Bénard magnetoconvection with rigid and thermally conducting boundaries. We have investigated two types of horizontal surfaces: (i) electrically conducting and (ii) boundaries which do not allow any outward current normal to the surface (magnetic vacuum conditions). For the case of electrically conducting boundaries, the critical Rayleigh number Rao(Q,Pr,Pm), the critical wave number ko(Q,Pr,Pm), and the frequency at the instability onset ω(Q,Pr,Pm) increase as the Chandrasekhar number Q is raised for fixed non-zero values of thermal Prandtl Pr and magnetic Prandtl number Pm. For small values of Pr, the frequency of oscillation ω at the primary instability shows a rapid increase with Pm for very small values of Pm followed by a decrease at relatively larger values of Pm. In the limit of Pr→0, Rao and ko are found to be independent of Q. However, the frequency ω increases with Q, but decreases with Pm in this limit. The oscillatory instability is possible at the onset of magnetoconvection if and only if Chandrasekhar's criterion is valid (i.e., Pm > Pr) and Q is raised above a critical value Qc(Pr,Pm) such that the product Pm*Qc≈91 for large Pm. For the stellar interior of an astrophysical body (Pm≈10−4 and Pr≈10−8), the value of this product Pm*Qc≈230. The boundary conditions for magnetic vacuum change the critical values of Rayleigh number, wave number, and frequency of oscillation at the onset. The oscillatory magnetoconvection occurs in this case, if Q>Qc, where Pm*Qc≈42 for large Pm. For steller interior, this value is approximately 64. A low-dimensional model is also constructed to study various patterns near the onset of oscillatory convection for rigid, thermally and electrically conducting boundaries. The model shows standing and drifting fluid patterns in addition to flow reversal close to the onset of magnetoconvection.
A simplified focusing and astigmatism correction method for a scanning electron microscope
Authors: Lu Yihua , Zhang Xianmin , Li Hai
Published: January 2018

Defocus and astigmatism can lead to blurred images and poor resolution. This paper presents a simplified method for focusing and astigmatism correction of a scanning electron microscope (SEM). The method consists of two steps. In the first step, the fast Fourier transform (FFT) of the SEM image is performed and the FFT is subsequently processed with a threshold to achieve a suitable result. In the second step, the threshold FFT is used for ellipse fitting to determine the presence of defocus and astigmatism. The proposed method clearly provides the relationships between the defocus, the astigmatism and the direction of stretching of the FFT, and it can determine the astigmatism in a single image. Experimental studies are conducted to demonstrate the validity of the proposed method.
EUV polarimetry for thin film and surface characterization and EUV phase retarder reflector development
Authors: Gaballah A. E. H. , Nicolosi P. , Ahmed Nadeem , Jimenez K. , Pettinari G. , Gerardino A. , Zuppella P.
Published: January 2018

The knowledge and the manipulation of light polarization state in the vacuum ultraviolet and extreme ultraviolet (EUV) spectral regions play a crucial role from materials science analysis to optical component improvements. In this paper, we present an EUV spectroscopic ellipsometer facility for polarimetry in the 90-160 nm spectral range. A single layer aluminum mirror to be used as a quarter wave retarder has been fully characterized by deriving the optical and structural properties from the amplitude component and phase difference δ measurements. The system can be suitable to investigate the properties of thin films and optical coatings and optics in the EUV region.
Strongly bound excitons in monolayer PtS2 and PtSe2
Authors: Sajjad M. , Singh N. , Schwingenschlögl U.
Published: January 2018

Based on first-principles calculations, the structural, electronic, and optical properties of monolayers PtS2 and PtSe2 are investigated. The bond stiffnesses and elastic moduli are determined by means of the spring constants and strain-energy relations, respectively. Dynamic stability is confirmed by calculating the phonon spectra, which shows excellent agreement with experimental reports for the frequencies of the Raman-active modes. The Heyd-Scuseria-Ernzerhof functional results in electronic bandgaps of 2.66 eV for monolayer PtS2 and 1.74 eV for monolayer PtSe2. G0W0 calculations combined with the Bethe-Salpeter equation are used to predict the optical spectra and exciton binding energies (0.78 eV for monolayer PtS2 and 0.60 eV for monolayer PtSe2). It turns out that the excitons are strongly bound and therefore very stable against external perturbations.
Generation and characterization of field-emitting surface dielectric barrier discharges in liquids
Authors: Kawamura Tomohisa , Kanno Moriyuki , Stauss Sven , Kuribara Koichi , Pai David Z. , Ito Tsuyohito , Terashima Kazuo
Published: January 2018

Field-emitting surface dielectric barrier discharges (FESDBDs), previously generated in CO2 from high pressures up to supercritical conditions using 10 kHz ac excitation, were investigated in non-aqueous liquid CO2 and liquid silicone oil. In both liquids, the maximum amount of negative charge Q−deposited as a function of the applied voltage amplitude was consistent with the Fowler–Nordheim equation, which demonstrated the presence of field emission. Furthermore, purely continuum optical emission spectra attributable to electron-neutral bremsstrahlung were confirmed. The fact that these characteristics were identical to those in high-pressure CO2 reported from previous research shows that FESDBDs can be generated independently of the medium type and that they are low-power (on the order of 10 mW) discharges. To investigate the charging function of FESDBDs, the motion of fine particles suspended above the FESDBDs was studied by high-speed imaging. It revealed that the speed of fine particles affected by the FESDBDs depends on the particle size, the FESDBDs' function being to charge fine particles.
Compressibility effects on a shear flow in strongly coupled dusty plasma. I. A study using computational fluid dynamics
Authors: Gupta Akanksha , Ganesh Rajaraman
Published: January 2018

We study compressibility effects on the two-dimensional strongly coupled dusty plasma by means of computational fluid dynamics (CFD) with the Kolmogorov flow as an initial shear flow profile. Nonlinear compressible vortex flow dynamics and other linear and nonlinear properties of such flow in the presence of variable density, pressure, and electrostatic potential are addressed using a generalised compressible hydrodynamic model. The stabilizing effect of compressibility on the unstable shear flows in the presence of strong correlation (τm>0) is presented. Increasing the Mach number relatively reduces the growth-rate of perturbation. On the other hand, strong correlation makes the medium to be more unstable and increases the growth rate. Using an eigen value solver, various linear properties of compressible Kolmogorov flow have been investigated for a range of variable parameters, for example, Mach number, Reynolds number, and viscoelastic coefficient (τm). Compressible Kolmogorov flow becomes unstable above a critical value of the Reynolds number (Rc), and below Rc, the shear flow is found to be neutrally stable. In this study, it is found that the viscoelasticity reduces the value of Rc. For our choice of parameters, at τm=τmc, the compressible Kolmogorov flow becomes unconditionally unstable and no Rc exists for values of τm higher than τmc. To address the nonlinear properties, for example, mode-mode interaction due to the presence of nonlinearity in the fluid, vortex formation, etc., a massively parallelized Advanced Generalized SPECTral Code (AG-Spect) has been developed. AG-Spect, a newly developed code, is an efficient tool to solve any set of nonlinear fluid dynamic equations. A good agreement in linear growth rates obtained from the eigen value solver and time dependent simulation (AG-Spect) is found. In our CFD study, the suppression of instability, elongated vortex structures, pattern formation, nonlinear saturation, and visco-elastic oscillations in perturbed kinetic energy have been observed for various values of Mach number, Reynolds number and τm.
High growth rate hydride vapor phase epitaxy at low temperature through use of uncracked hydrides
Authors: Schulte Kevin L. , Braun Anna , Simon John , Ptak Aaron J.
Published: January 2018

We demonstrate hydride vapor phase epitaxy (HVPE) of GaAs with unusually high growth rates (RG) at low temperature and atmospheric pressure by employing a hydride-enhanced growth mechanism. Under traditional HVPE growth conditions that involve growth from Asx species, RG exhibits a strong temperature dependence due to slow kinetics at the surface, and growth temperatures >750 °C are required to obtain RG > 60 μm/h. We demonstrate that when the group V element reaches the surface in a hydride, the kinetic barrier is dramatically reduced and surface kinetics no longer limit RG. In this regime, RG is dependent on mass transport of uncracked AsH3 to the surface. By controlling the AsH3 velocity and temperature profile of the reactor, which both affect the degree of AsH3 decomposition, we demonstrate tuning of RG. We achieve RG above 60 μm/h at temperatures as low as 560 °C and up to 110 μm/h at 650 °C. We incorporate high-RG GaAs into solar cell devices to verify that the electronic quality does not deteriorate as RG is increased. The open circuit voltage (VOC), which is a strong function of non-radiative recombination in the bulk material, exhibits negligible variance in a series of devices grown at 650 °C with RG = 55–110 μm/h. The implications of low temperature growth for the formation of complex heterostructure devices by HVPE are discussed.
Interface engineering of CsPbI3-black phosphorus van der Waals heterostructure
Authors: Liu Biao , Long Mengqiu , Cai Meng-Qiu , Yang Junliang
Published: January 2018

Interface Engineering is an effective route to tune structural and electrical properties in semiconductor heterostructures. Two kinds of typical van der Waals (vdW)-type electrical contacts, i.e., the electrical contacts of the Pb-I interface and Cs-I interface with a black phosphorus (BP) monolayer, respectively, in CsPbI3-BP heterostructures are studied by first-principles calculations. The electronic band structures of both CsPbI3 slabs and the BP monolayer are preserved in the combined vdW CsPbI3-BP heterostructures. The heterostructure of the Pb-I interface contacting with BP demonstrates the type-I band alignment, and the Cs-I interface contacting with the BP heterostructure demonstrates the type-II band alignment. The reason for the energy level shift is the work function difference of CsPbI3 slabs relative to the BP monolayer, which drives electrons and holes to move spontaneously. In addition, the CsPbI3-BP heterostructures show much better optical properties than CsPbI3 slabs. The light absorptions are enhanced in the CsPbI3-BP heterostructures, especially in the infrared region, which would improve the use of infrared light in CsPbI3 perovskite solar cells. This work suggests that such inorganic perovskite-BP heterostructures have significant potential for future optoelectronic applications and can enable broad possibilities with compositional tunability in inorganic perovskites.
Amplification and stabilization of large-amplitude propagating spin waves by parametric pumping
Authors: Verba Roman , Carpentieri Mario , Finocchio Giovanni , Tiberkevich Vasil , Slavin Andrei
Published: January 2018

The interaction of a localized parametric pumping with spin waves of different amplitudes, propagating in a ferromagnetic nanowire, is studied analytically and by micromagnetic simulations. It is shown that parametric amplification of spin waves by localized pumping becomes less efficient with an increase in the spin wave amplitude due to the influence of nonlinear 4-magnon processes. In a certain range of spin wave amplitudes, the parametric amplifier acts as a stabilizer of the spin wave amplitude, as its action significantly reduces the spread of the spin wave amplitude in the vicinity of a certain mean value. The stabilization effect becomes more pronounced for higher pumping strength and larger relative lengths of the pumping localization region, compared to the spin wave mean free path. In contrast, the use of relatively short pumping localization regions allows one to efficiently amplify large-amplitude nonlinear spin waves.
Relation between level of autumn dormancy and salt tolerance in lucerne (Medicago sativa)
Authors: Huang Kunyong , Dai Xiaoxia , Xu Yiquan , Dang Shibing , Shi Tianran , Sun Jianmin , Wang Kehua
Published: January 2018

Experiments were conducted to study the relationship between autumn (fall) dormancy rating (FDR) and salt tolerance of lucerne (alfalfa, Medicago sativa L.). Seeds of eight cultivars with different FDRs (range 2.0–10.2) were germinated in a growth chamber under five concentrations of NaCl (range 0–1.2%). A subordinate function value method was adopted for comprehensive evaluation of salt tolerance of the lucerne cultivars. Seed germination rate and germination potential, and seedling electrolyte leakage, shoot length, root length, fresh weight, root : shoot length ratio, Na+ and K+ concentrations and K+ : Na+ ratio were used as the indices of evaluation. Under 1.2% salt treatment, salt-tolerance ranking of the cultivars was WL656HQ > WL440HQ > WL712HQ > WL525HQ > WL343HQ > WL319HQ > WL363HQ > WL168HQ, with respective FDRs of 9.3, 6.0, 10.2, 8.2, 3.9, 2.8, 4.9 and 2.0. The results of this study show that non-dormant cultivars were generally more salt tolerant than dormant cultivars.
No longer a west-side story – pesticide resistance discovered in the eastern range of a major Australian crop pest, Halotydeus destructor (Acari: Penthaleidae)
Authors: Maino James L. , Binns Matthew , Umina Paul
Published: January 2018

The redlegged earth mite, Halotydeus destructor (Tucker) (Acari: Penthaleidae), is an important pest of pastures, broad-acre crops, and vegetables across southern Australia. Populations of H. destructor in Western Australia have been known to be resistant to pyrethroid and organophosphorus pesticides since 2006 and 2014, respectively. Resistant populations are currently widespread across Western Australia’s southern growing region but have, until now, remained undetected in the large south-eastern Australian range of H. destructor, despite ongoing resistance screening since 2006. Following reports of a field control failure in the Upper South East district in South Australia in 2016, resistance testing determined this South Australian population was resistant to pyrethroid and organophosphorus pesticides. The levels of resistance discovered were similar to resistant H. destructor populations in Western Australia, which are associated with chemical control failures. This work confirms for the first-time that pesticide resistant populations of H. destructor are no longer isolated to Western Australia.
Climate vulnerability and resilience in the most valuable North American fishery
Authors: Le Bris Arnault , Mills Katherine E. , Wahle Richard A. , Chen Yong , Alexander Michael A. , Allyn Andrew J. , Schuetz Justin G. , Scott James D. , Pershing Andrew J.
Published: January 2018

Significance

Climate change is impacting global fisheries and societies that depend on them. Identifying climate adaptation measures requires understanding how environmental changes and management policies interact in driving fishery productivity. Coincident with the recent exceptional warming of the northwest Atlantic Ocean, the American lobster has become the most valuable fishery resource in North America. Here we show that interactions between warming waters, ecosystem changes, and differences in conservation efforts led to the simultaneous collapse of lobster fishery in southern New England and record-breaking landings in the Gulf of Maine. Our results demonstrate that sound, widely adopted fishery conservation measures based on fundamental biological principles can help capitalize on gains and mitigate losses caused by global climate change.
Methyltransferases of gentamicin biosynthesis
Authors: Li Sicong , Guo Junhong , Reva Anna , Huang Fanglu , Xiong Binbin , Liu Yuanzhen , Deng Zixin , Leadlay Peter F. , Sun Yuhui
Published: January 2018

Gentamicin C complex from
Micromonospora echinospora
remains a globally important antibiotic, and there is revived interest in the semisynthesis of analogs that might show improved therapeutic properties. The complex consists of five components differing in their methylation pattern at one or more sites in the molecule. We show here, using specific gene deletion and chemical complementation, that the gentamicin pathway up to the branch point is defined by the selectivity of the methyltransferases GenN, GenD1, and GenK. Unexpectedly, they comprise a methylation network in which early intermediates are ectopically modified. Using whole-genome sequence, we have also discovered the terminal 6′-
N
-methyltransfer required to produce gentamicin C2b from C1a or gentamicin C1 from C2, an example of an essential biosynthetic enzyme being located not in the biosynthetic gene cluster but far removed on the chromosome. These findings fully account for the methylation pattern in gentamicins and open the way to production of individual gentamicins by fermentation, as starting materials for semisynthesis.
Heritable aspects of biological motion perception and its covariation with autistic traits
Authors: Wang Ying , Wang Li , Xu Qian , Liu Dong , Chen Lihong , Troje Nikolaus F. , He Sheng , Jiang Yi
Published: January 2018

Significance

Impaired visual processing of biological motion (BM) is inextricably linked to compromised social cognitive abilities in autism spectrum disorder (ASD). Using behavioral genetic methodology, we demonstrate that genes contribute to interindividual variation in BM perception abilities and autistic traits. More importantly, the ability to process the local motion rather than the global configuration of BM is heritable, and the former is negatively correlated with autistic traits, with the covariance mainly attributable to shared genetic factors. These findings provide evidence that the ability to process BM and its close connection with social cognitive skills have a genetic basis and highlight the potential for treating the ability to process local BM information as a distinct hallmark of social cognition.
Centipedes subdue giant prey by blocking KCNQ channels
Authors: Luo Lei , Li Bowen , Wang Sheng , Wu Fangming , Wang Xiaochen , Liang Ping , Ombati Rose , Chen Junji , Lu Xiancui , Cui Jianmin , Lu Qiumin , Zhang Longhua , Zhou Ming , Tian Changlin , Yang Shilong , Lai Ren
Published: January 2018

Centipedes can subdue giant prey by using venom, which is metabolically expensive to synthesize and thus used frugally through efficiently disrupting essential physiological systems. Here, we show that a centipede (Scolopendra subspinipes mutilans, ∼3 g) can subdue a mouse (∼45 g) within 30 seconds. We found that this observation is largely due to a peptide toxin in the venom, SsTx, and further established that SsTx blocks KCNQ potassium channels to exert the lethal toxicity. We also demonstrated that a KCNQ opener, retigabine, neutralizes the toxicity of a centipede’s venom. The study indicates that centipedes’ venom has evolved to simultaneously disrupt cardiovascular, respiratory, muscular, and nervous systems by targeting the broadly distributed KCNQ channels, thus providing a therapeutic strategy for centipede envenomation.
Tactile distance illusions reflect a coherent stretch of tactile space
Authors: Fiori Federico , Longo Matthew R.
Published: January 2018

Significance

Spatial illusions, such as the classic horizontal–vertical illusion, have played a major role in theories of visual organization. Although analogous illusions in touch have been known since the 19th century, they have been much less studied, and there is no general theory of their mechanistic basis. We developed and tested a model of tactile distance illusions in terms of a geometrically simple stretch of tactile space. We demonstrate that the pattern of perceived tactile distances across orientations is consistent with the model’s predictions. Similar results were apparent on the hand dorsum, palm, and forehead, suggesting it is a general characteristic of tactile spatial perception. These results show that tactile distance illusions reflect a geometrically simple deformation of tactile space.
Redirection of lipid flux toward phospholipids in yeast increases fatty acid turnover and secretion
Authors: Ferreira Raphael , Teixeira Paulo Gonçalves , Siewers Verena , Nielsen Jens
Published: January 2018

Significance

Replacement of nonrenewable petrochemicals and liquid fuels requires sustainable production of oleochemicals. Free fatty acids (FFAs) are versatile molecules that can be produced by microbial fermentation and are used as precursors for production of these oleochemicals. In the past few years, we have seen major advancements in improving the yeast
Saccharomyces cerevisiae
for FFA production. Despite these successes, lipid metabolism is highly complex, and the pathways and metabolites involved in the formation of FFAs in yeast remain incompletely understood. In this work, we make important advancements in understanding the dynamics of FFA formation in the cell and explore the role of phospholipids in this process.
High-resolution cryo-EM structures of actin-bound myosin states reveal the mechanism of myosin force sensing
Authors: Mentes Ahmet , Huehn Andrew , Liu Xueqi , Zwolak Adam , Dominguez Roberto , Shuman Henry , Ostap E. Michael , Sindelar Charles V.
Published: January 2018

Myosins adjust their power outputs in response to mechanical loads in an isoform-dependent manner, resulting in their ability to dynamically adapt to a range of motile challenges. Here, we reveal the structural basis for force-sensing based on near-atomic resolution structures of one rigor and two ADP-bound states of myosin-IB (myo1b) bound to actin, determined by cryo-electron microscopy. The two ADP-bound states are separated by a 25° rotation of the lever. The lever of the first ADP state is rotated toward the pointed end of the actin filament and forms a previously unidentified interface with the N-terminal subdomain, which constitutes the upper half of the nucleotide-binding cleft. This pointed-end orientation of the lever blocks ADP release by preventing the N-terminal subdomain from the pivoting required to open the nucleotide binding site, thus revealing how myo1b is inhibited by mechanical loads that restrain lever rotation. The lever of the second ADP state adopts a rigor-like orientation, stabilized by class-specific elements of myo1b. We identify a role for this conformation as an intermediate in the ADP release pathway. Moreover, comparison of our structures with other myosins reveals structural diversity in the actomyosin binding site, and we reveal the high-resolution structure of actin-bound phalloidin, a potent stabilizer of filamentous actin. These results provide a framework to understand the spectrum of force-sensing capacities among the myosin superfamily.
A neurochemical hypothesis for the origin of hominids
Authors: Raghanti Mary Ann , Edler Melissa K. , Stephenson Alexa R. , Munger Emily L. , Jacobs Bob , Hof Patrick R. , Sherwood Chet C. , Holloway Ralph L. , Lovejoy C. Owen
Published: January 2018

Significance

Two factors vital to the human clade are our unique demographic success and our social facilities including language, empathy, and altruism. These have always been difficult to reconcile with individual reproductive success. However, the striatum, a region of the basal ganglia, modulates social behavior and exhibits a unique neurochemical profile in humans. The human signature amplifies sensitivity to social cues that encourage social conformity and affiliative behavior and could have favored provisioning and monogamy in emergent hominids, consilient with the simultaneous origin of upright walking and elimination of the sectorial canine. Such exceptional neurochemistry would have favored individuals especially sensitive to social cues throughout later human evolution and may account for cerebral cortical expansion and the emergence of language.
Pulse electrodeposited RuO2 electrodes for high-performance supercapacitor applications
Authors: Arunachalam R. , Prataap R. K.Vishnu , Pavul Raj R. , Mohan S. , Vijayakumar J. , Péter L. , Al Ahmad Mahmoud
Published: January 2018

The present work addresses high-performance Ruthenium Oxide (RuO2) electrodes prepared by using a simple pulse electrodeposition method. For the comparison purpose, two different precursors, namely, ruthenium (III) nitrosyl sulphate (RuNS) and ruthenium trichloride (RuCl3), were used in this study. The coatings were subjected to material characterisation such as Field Emission Scanning Electron Microscopy and Energy-Dispersive X-ray Spectroscopy, X-ray diffraction and Transmission electron microscopy as well as electrochemical characterisation such as Cyclic Voltammetry, Electrochemical Impedance Spectroscopy and charge/discharge. The RuNS–RuO2 coating exhibited excellent specific capacitance (1724 F/g at 5 A/g) with a remarkable rate capability. This value is significantly higher (52%) than the value obtained for RuCl3–RuO2 electrode material at 5 A/g. The findings provide valuable information on the potential use of RuNS as a precursor for synthesising RuO2 and pulse electrodeposition process to produce electrodes for supercapacitors.
Characterization of Trichuris muris secreted proteins and extracellular vesicles provides new insights into host–parasite communication
Authors: Eichenberger Ramon M. , Talukder Md Hasanuzzaman , Field Matthew A. , Wangchuk Phurpa , Giacomin Paul , Loukas Alex , Sotillo Javier
Published: January 2018

Whipworms are parasitic nematodes that live in the gut of more than 500 million people worldwide. Owing to the difficulty in obtaining parasite material, the mouse whipworm Trichuris muris has been extensively used as a model to study human whipworm infections. These nematodes secrete a multitude of compounds that interact with host tissues where they orchestrate a parasitic existence. Herein we provide the first comprehensive characterization of the excretory/secretory products of T. muris. We identify 148 proteins secreted by T. muris and show for the first time that the mouse whipworm secretes exosome‐like extracellular vesicles (EVs) that can interact with host cells. We use an Optiprep® gradient to purify the EVs, highlighting the suitability of this method for purifying EVs secreted by a parasitic nematode. We also characterize the proteomic and genomic content of the EVs, identifying >350 proteins, 56 miRNAs (22 novel) and 475 full‐length mRNA transcripts mapping to T. muris gene models. Many of the miRNAs putatively mapped to mouse genes are involved in regulation of inflammation, implying a role in parasite‐driven immunomodulation. In addition, for the first time to our knowledge, colonic organoids have been used to demonstrate the internalization of parasite EVs by host cells. Understanding how parasites interact with their host is crucial to develop new control measures. This first characterization of the proteins and EVs secreted by T. muris provides important information on whipworm–host communication and forms the basis for future studies.
The Cullin-3–Rbx1–KCTD10 complex controls endothelial barrier function via K63 ubiquitination of RhoB
Authors: Kovačević Igor , Sakaue Tomohisa , Majoleé Jisca , Pronk Manon C. , Maekawa Masashi , Geerts Dirk , Fernandez-Borja Mar , Higashiyama Shigeki , Hordijk Peter L.
Published: January 2018

RhoGTPases control endothelial cell (EC) migration, adhesion, and barrier formation. Whereas the relevance of RhoA for endothelial barrier function is widely accepted, the role of the RhoA homologue RhoB is poorly defined. RhoB and RhoA are 85% identical, but RhoB’s subcellular localization and half-life are uniquely different. Here, we studied the role of ubiquitination for the function and stability of RhoB in primary human ECs. We show that the K63 polyubiquitination at lysine 162 and 181 of RhoB targets the protein to lysosomes. Moreover, we identified the RING E3 ligase complex Cullin-3–Rbx1–KCTD10 as key modulator of endothelial barrier integrity via its regulation of the ubiquitination, localization, and activity of RhoB. In conclusion, our data show that ubiquitination controls the subcellular localization and lysosomal degradation of RhoB and thereby regulates the stability of the endothelial barrier through control of RhoB-mediated EC contraction.
A Service Ready for Total War? The State of the Royal Navy in July 1914
Authors: Seligmann Matthew S
Published: January 2018

In early 1914 Britain’s naval leadership decided to call a conference of flag officers at which the most pressing issues then facing the Royal Navy could be aired and discussed. The conference was scheduled for the end of July 1914. Owing to the European crisis that erupted at just the very moment when it was supposed to take place, the conference was never held. However, the bulk of the paperwork still exists. This documentation provides a unique snapshot of the thinking of Britain’s key naval commanders on strategic, tactical and materiel considerations at the very moment when they were about to embark upon the most serious of examinations, the test of a major war. This article uses these files to evaluate the extent to which the Royal Navy was aware of the challenges that were about to confront it and the strengths and weaknesses that would aid or hinder them in this task. It thereby assesses the service’s readiness for total war, concluding that it was far from the conservative body of popular caricature.
Mechanistic peculiarities of activation-induced mobilization of cytotoxic effector proteins in human T cells
Authors: Lettau Marcus , Armbrust Fred , Dohmen Katharina , Drews Lisann , Poch Tobias , Dietz Michelle , Kabelitz Dieter , Janssen Ottmar
Published: January 2018

It is widely accepted that cytotoxic T and NK cells store effector proteins including granzymes, perforin and Fas ligand (FasL) in intracellular granules, often referred to as secretory lysosomes. Upon target cell encounter, these organelles are transported to the cytotoxic immunological synapse, where they fuse with the plasma membrane to release the soluble effector molecules and to expose transmembrane proteins including FasL on the cell surface. We previously described two distinct species of secretory vesicles in T and NK cells that differ in size, morphology and protein loading, most strikingly regarding FasL and granzyme B. We now show that the signal requirements for the mobilization of one or the other granule also differ substantially. We report that prestored FasL can be mobilized independent of extracellular Ca2+, whereas the surface exposure of lysosome-associated membrane proteins (Lamps; CD107a and CD63) and the release of granzyme B are calcium-dependent. The use of selective inhibitors of actin dynamics unequivocally points to different transport mechanisms for individual vesicles. While inhibitors of actin polymerization/dynamics inhibit the surface appearance of prestored FasL, they increase the activation-induced mobilization of CD107a, CD63 and granzyme B. In contrast, inhibition of the actin-based motor protein myosin 2a facilitates FasL-, but impairs CD107a-, CD63- and granzyme B mobilization. From our data, we conclude that distinct cytotoxic effector granules are differentially regulated with respect to signaling requirements and transport mechanisms. We suggest that a T cell might ‘sense’ which effector proteins it needs to mobilize in a given context, thereby increasing efficacy while minimizing collateral damage.
All-dielectric meta-optics and non-linear nanophotonics
Authors: Kivshar Yuri
Published: January 2018

Most optical metamaterials fabricated and studied to date employ metallic components resulting in significant losses, heat and overall low efficiencies. A new era of metamaterial physics is associated with all-dielectric meta-optics, which employs electric and magnetic Mie resonances of subwavelength particles with high refractive index for an optically induced magnetic response, thus underpinning a new approach to design and fabricate functional and practical metadevices. Here we review the recent developments in meta-optics and subwavelength dielectric photonics and demonstrate that the Mie resonances can play a crucial role in the realization of the unique functionalities of meta-atoms, also driving novel effects in the fields of metamaterials and nanophotonics. We discuss the recent research frontiers in all-dielectric meta-optics and uncover how Mie resonances can be employed for a flexible control of light with full phase and amplitude engineering, including unidirectional metadevices, highly transparent metasurfaces, non-linear nanophotonics and topological photonics.
Evidence for GeV cosmic rays from white dwarfs in the local cosmic ray spectra and in the gamma-ray emissivity of the inner Galaxy
Authors: Kamae Tuneyoshi , Lee Shiu-Hang , Makishima Kazuo , Shibata Shinpei , Shigeyama Toshikazu
Published: January 2018

Recent observations found that electrons are accelerated to ∼10 GeV and emit synchrotron hard X-rays in two magnetic white dwarfs (WDs), also known as cataclysmic variables (CVs). In nova outbursts of WDs, multi-GeV gamma-rays were detected, implying that protons are accelerated to 100 GeV or higher. In recent optical surveys, the WD density is found to be higher near the Sun than in the Galactic disk by a factor ∼2.5. The cosmic rays (CRs) produced by local CVs and novae will accumulate in the local bubble for 106–107 yr. On these findings, we search for CRs from historic CVs and novae in the observed CR spectra. We model the CR spectra at the heliopause as sums of Galactic and local components based on observational data as much as possible. The initial Galactic CR electron and proton spectra are deduced from the gamma-ray emissivity, the local electron spectrum from the hard X-ray spectra at the CVs, and the local proton spectrum from gamma-ray spectra at novae. These spectral shapes are then expressed in a simple set of polynomial functions of CR energy and regressively fitted until the high-energy (>100 GeV) CR spectra near Earth and the Voyager-1 spectra at the heliopause are reproduced. We then extend the modeling to nuclear CR spectra and find that one spectral shape fits all local nuclear CRs, and that the apparent hardening of the nuclear CR spectra is caused by the roll-down of local nuclear spectra around 100–200 GeV. All local CR spectra populate a limited energy band below 100–200 GeV and enhance gamma-ray emissivity below ∼10 GeV. Such an enhancement is observed in the inner Galaxy, suggesting the CR fluxes from CVs and novae are substantially higher there.
National Beef Quality Audit–2016: assessment of cattle hide characteristics, offal condemnations, and carcass traits to determine the quality status of the market cow and bull beef industry
Authors: Harris McKensie K , Eastwood L Clay , Boykin Courtney A , Arnold Ashley N , Gehring Kerri B , Hale Daniel S , Kerth Christopher R , Griffin Davey B , Savell Jeffrey W , Belk Keith E , Woerner Dale R , Hasty Josh D , Delmore Robert J , Martin Jennifer N , Lawrence Ty E , McEvers Trenton J , VanOverbeke Deborah L , Mafi Gretchen G , Pfeiffer Morgan M , Schmidt Ty B , Maddock Robert J , Johnson D Dwain , Carr Chad C , Scheffler Jason M , Pringle T Dean , Stelzleni Alexander M
Published: January 2018

To continue the series that began in 1994, the National Beef Quality Audit (NBQA) – 2016 was conducted to quantify the quality status of the market cow and bull beef sector, as well as determine improvements made in the beef and dairy industry since 2007. The NBQA-2016 was conducted from March through December of 2016, and assessed hide-on carcasses (n = 5,278), chilled carcasses (n = 4,285), heads (n = 5,720), and offal items (n = 4,800) in 18 commercial processing facilities throughout the United States. Beef cattle were predominantly black-hided; 68.0% of beef cows and 67.2% of beef bulls possessed a black hide. Holstein was the predominant type of dairy animal observed. Just over half (56.0%) of the cattle surveyed had no mud contamination on the hide, and when mud was present, 34.1% of cattle only had small amounts. Harvest floor assessments found 44.6% of livers, 23.1% of lungs, 22.3% of hearts, 20.0% of viscera, 8.2% of heads, and 5.9% of tongues were condemned. Liver condemnations were most frequently due to abscess presence. In contrast, contamination was the primary reason for condemnation of all other offal items. Of the cow carcasses surveyed, 17.4% carried a fetus at the time of harvest. As expected, mean carcass weight and loin muscle area values observed for bulls were heavier and larger than cows. The marbling scores represented by cull animal carcasses were most frequently slight and traces amounts. Cow carcasses manifested a greater amount of marbling on average than bull carcasses. The predominant fat color score showed all carcasses surveyed had some level of yellow fat. Only 1.3% of carcasses exhibited signs of arthritic joints. Results of the NBQA-2016 indicate there are areas in which the beef and dairy industries have improved and areas that still need attention to prevent value loss in market cows and bulls.
Effects of shade-coffee certification programs on bird, trees and butterfly diversity in Colombia
Authors: Gomez Juan Pablo , Ortiz-Acevedo Elena , Botero Jorge E.
Published: January 2018

In the last decade coffee certification programs have grown rapidly in Latin America, encouraging producers to harvest coffee based on production standards intended to enhance biodiversity conservation. However, few studies have tested whether such programs have a positive conservation impact. To date, research has focused on comparing community similarity between forests and plantations, but the question of whether certified plantations provide refuges for biodiversity in regions where all the forest has been lost remains untested. Here, we compare bird, butterfly and plant communities in highly deforested regions in Santander, Colombia, to determine the potential conservation role of two certification programs: Rainforest Alliance and Rainforest Alliance+Organic. We used 13 farms to census birds, butterflies, and trees, and quantified structural characteristics of the shade. We found little difference in most measures of diversity and composition of birds, butterfly and plant communities between types of plantations. However, despite high variation across farms, butterfly richness and abundance increased with the decrease in the use of pesticides in plantations. These results suggest that reduced use of chemical compounds in certified coffee plantations might enhance conservation of butterfly communities. The biodiversity associated with these coffee plantations and the high deforestation rates in Santander, suggest that irrespective of their certification type they provide the last refuges for biodiversity conservation in this region.
Aerothermodynamic study of a small hypersonic plane
Authors: D’Oriano Vera , Savino Raffaele , Visone Michele
Published: January 2018

Purpose

This paper aims to present an aerothermodynamic analysis of a new concept of a small hypersonic airplane. Aerodynamics characteristics for different flow conditions encountered during the missions are analyzed. The effects of elevons deflection for pitch control and of the presence of engines on aerodynamic performances are also investigated for different flight conditions. The effects of boundary layer laminar–turbulent transition on aerodynamic heating are studied to preliminarily identify proper materials that can sustain the hypersonic phase.

Design/methodology/approach

Aerodynamic characteristics are predicted by means of the semi-empirical aerodynamic prediction code Missile DATCOM and computational fluid dynamics simulations. Computational fluid dynamics analysis is also performed to investigate aerodynamic heating phenomenon.

Findings

Major discrepancies between the results offered by the two methods have been registered in transonic regime, whereas in subsonic and super-hypersonic conditions, Missile DATCOM confirms to be a suitable tool for preliminary design steps. The results of the analysis show that for the identification of the materials that can sustain the hypersonic phase, the turbulent solution must be taken into account. Carbon fiber reinforced ceramics composite materials seem particularly well suited for the nose, wing and vertical tail leasing edges and control surfaces, while titanium alloys could be used for the rest of the vehicle surface.

Originality/value

This new concept of vehicle is designed both for point-to-point medium range hypersonic transportation and long duration suborbital space tourism missions, by integrating available technologies developed for aeronautical and space systems.
PIL simulations of an FWUAV under windy conditions
Authors: Ülker Hakan , Baykara Cemal , Özsoy Can
Published: January 2018

Purpose

A fixed wing unmanned aerial vehicle (FWUAV) is targeted to perform processor in the loop (PIL) simulations for the flight scenarios such as straight and level, level climb, level turn, climbing turn and level steady heading sideslip under windy conditions such as steady wind (SW) and wind gust (WG) in a desired and controlled manner.

Design/methodology/approach

The constrained multi-input–multi-output (MIMO) lateral and longitudinal linear models-based model predictive controllers (MPCs) which are proposed in a previous study (Ulker et al., 2017) are tested in the PIL simulations under specified windy conditions. BeagleBone Black Rev C is used as a target hardware or processor in the PIL simulations.

Findings

The results of the PIL simulations show that the MPCs proposed in the previous study can achieve satisfactory performance and flying qualities for the all flight scenarios handled in this paper under windy conditions.

Practical implications

The MPCs proposed in the previous study can be easily implemented in the real world to a low-cost and small-sized board like BeagleBone Black Rev C which is used in this paper.

Originality/value

The proposed MPCs in the previous study which are capable of providing more flexibility in terms of tracking complex trajectories are showed to be able to be implemented to real system by means of PIL simulations under the changeable windy conditions which are difficult for performance tests.
Swarm system for CubeSats
Authors: Zanette Luca , Reyneri Leonardo , Bruni Giuseppe
Published: January 2018

Purpose

This paper aims to present an innovative system able to establish an inter-satellite communication crosslink and to determine the mutual physical positioning for CubeSats belonging to a swarm.

Design/methodology/approach

Through a system involving a smart antenna array managed by a beamforming control strategy, every CubeSat of the swarm can measure the direction of arrival (DOA) and the distance (range) to estimate the physical position of the received signal. Moreover, during the transmission phase, the smart antenna shapes the beam to establish a reliable and directive communication link with the other spacecraft and/or with the ground station. Furthermore, the authors introduce a deployable structure fully developed at Politecnico di Torino that is able to increase the external surface of CubeSats: this surface allows to gain the interspace between elements of the smart antenna.

Findings

As a consequence, the communication crosslink, the directivity and the detection performance of the DOA system in terms of directivity and accuracy are improved.

Practical implications

Moreover, the deployable structure offers a greater usable surface, so a larger number of solar panels can be used. This guarantees up to 25 W of average power supply for the on-board systems and for transmission on a one-unit (1U) CubeSat (10 × 10 × 10 cm).

Originality/value

This paper describes the physical implementation of the antenna array system on a 1U CubeSat by using the deployable structure developed. Depending on actuators and ability that every CubeSat disposes, various interaction levels between elements can be achieved, thus making the CubeSat constellation an efficient and valid solution for space missions.
System identification-based aeroelastic modelling for wing flutter
Authors: F. Promio Charles , Samikkannu Raja , Sura Niranjan K. , Mulla Shanwaz
Published: January 2018

Purpose

Ground vibration testing (GVT) results can be used as system parameters for predicting flutter, which is essential for aeroelastic clearance. This paper aims to compute GVT-based flutter in time domain, using unsteady air loads by matrix polynomial approximations.

Design/methodology/approach

The experimental parameters, namely, frequencies and mode shapes are interpolated to build an equivalent finite element model. The unsteady aerodynamic forces extracted from MSC NASTRAN are approximated using matrix polynomial approximations. The system matrices are condensed to the required shaker location points to build an aeroelastic reduced order state space model in SIMULINK.

Findings

The computed aerodynamic forces are successfully reduced to few input locations (optimal) for flutter simulation on unknown structural system (where stiffness and mass are not known) through a case study. It is demonstrated that GVT data and the computed unsteady aerodynamic forces of a system are adequate to represent its aeroelastic behaviour.

Practical implications

Airforce of every nation continuously upgrades its fleet with advanced weapon systems (stores), which demands aeroelastic flutter clearance. As the original equipment manufacturers does not provide the design data (stiffness and mass) to its customers, a new methodology to build an aeroelastic system of unknown aircraft is devised.

Originality/value

A hybrid approach is proposed, involving GVT data to build an aeroelastic state space system, using rationally approximated air loads (matrix polynomial approximations) computed on a virtual FE model for ground flutter simulation.
Aerodynamic performance of flying discs
Authors: Kamaruddin Noorfazreena , Potts Jonathan , Crowther William
Published: January 2018

Purpose

The purpose of this paper is to examine geometrical design influence of various types of flying discs on their flight performance from the aerodynamics perspective.

Design/methodology/approach

The lift, drag and moment coefficients of the discs were measured experimentally using a wind tunnel. Three types of golf discs and four sets of simpler parametric discs were studied to analyze and isolate the effect of design factors on these aerodynamic characteristics. Full six degree-of-freedom simulations of the discs were performed to visualize their flight trajectories and attitudes. These simulations, combined with the experimental data, provide details on the well-known “S-shaped” ground-path traced by a flying disc.

Findings

This paper reveals two key parameters to evaluate the flight performance of a disc: its coefficient of lift-to-drag ratio (CL/CD) and, more importantly, its coefficient of pitching moment (CM). The latter influences the tendency of the disc to yaw from its intended path, and the former influences its throwing distance.

Practical implications

The work suggests that to optimize the flight performance of a disc, the magnitudes and gradient of its CM should be minimized and its trim-point shifted from origin, while its CL/CD should be maximized with a flatter peak.

Originality/value

In this paper, the design parameters and the aerodynamic characteristics of various types of flying discs are analysed, compared and discussed in depth. Recommendations of design improvements to enhance the performance of any flying disc are offered as well.