Strong Elongation Research Articles

Intuition for the radial penetration of flux surface shaping in tokamaks

Using analytic calculations, the effects of the edge flux surface shape and the toroidal current profile on the penetration of flux surface shaping are investigated in a tokamak. It is shown that the penetration of shaping is determined by the poloidal variation of the poloidal magnetic field on the surface. This fact is used to investigate how different flux surface shapes penetrate from the edge. Then, a technique to separate the effects of magnetic pressure and tension in the Grad–Shafranov equation is presented and used to calculate radial profiles of strong elongation for nearly constant current profiles. Lastly, it is shown that more hollow toroidal current profiles are significantly better at conveying shaping from the edge to the core.

Fusidic Acid Targets Elongation Factor G in Several Stages of Translocation on the Bacterial Ribosome

The antibiotic fusidic acid (FA) targets elongation factor G (EF-G) and inhibits ribosomal peptide elongation and ribosome recycling, but deeper mechanistic aspects of FA action have remained unknown. Using quench flow and stopped flow experiments in a biochemical system for protein synthesis and taking advantage of separate time scales for inhibited (10 s) and uninhibited (100 ms) elongation cycles, a detailed kinetic model of FA action was obtained. FA targets EF-G at an early stage in the translocation process (I), which proceeds unhindered by the presence of the drug to a later stage (II), where the ribosome stalls. Stalling may also occur at a third stage of translocation (III), just before release of EF-G from the post-translocation ribosome. We show that FA is a strong elongation inhibitor (K50% ≈ 1 μm), discuss the identity of the FA targeted states, and place existing cryo-EM and crystal structures in their functional context.

High-Frequency Asymptotics for the Radar Cross-Section Computation of a Prolate Spheroid With High Aspect Ratio

The problem of high-frequency diffraction by elongated bodies is discussed in this paper. The asymptotics are governed by the elongation parameter, which is the ratio of the longitudinal wave dimensions of the body to its cross-section. The cases of axial incidence and that of incidence at a grazing angle to the axis are considered, and the asymptotics of the far field amplitude are developed. Comparisons with numerical results for a set of test problems show that the leading terms of the new asymptotics provide good approximation with respect to the rate of elongation in a uniform manner. Effects of strong elongation on the RCS are discussed .

VEGF-B selectively regenerates injured peripheral neurons and restores sensory and trophic functions.

VEGF-B primarily provides neuroprotection and improves survival in CNS-derived neurons. However, its actions on the peripheral nervous system have been less characterized. We examined whether VEGF-B mediates peripheral nerve repair. We found that VEGF-B induced extensive neurite growth and branching in trigeminal ganglia neurons in a manner that required selective activation of transmembrane receptors and was distinct from VEGF-A-induced neuronal growth. VEGF-B-induced neurite elongation required PI3K and Notch signaling. In vivo, VEGF-B is required for normal nerve regeneration: mice lacking VEGF-B showed impaired nerve repair with concomitant impaired trophic function. VEGF-B treatment increased nerve regeneration, sensation recovery, and trophic functions of injured corneal peripheral nerves in VEGF-B-deficient and wild-type animals, without affecting uninjured nerves. These selective effects of VEGF-B on injured nerves and its lack of angiogenic activity makes VEGF-B a suitable therapeutic target to treat nerve injury.

Process‐induced phase and crystal morphologies in water‐assisted injection molded polypropylene/polymeric β‐nucleating agent blend parts

By adding a polymeric β‐nucleating agent (acrylonitrile–styrene copolymer, SAN), in situ microfibril reinforced isotactic polypropylene (iPP)/SAN blend parts with high contents of β‐form crystals and transcrystals were molded via water‐assisted injection molding (WAIM). Thanks to the unique stress and temperature fields occurring during the WAIM, SAN microfibers formed across the whole residual wall of iPP/SAN blend parts with relatively large thickness. Numerical simulations on high‐pressure water penetration and cooling stages of the WAIM were carried out to reveal the stress and temperature fields. Comprehensive analysis of both experimental and simulated results showed that not only the shear flow field but also elongational flow field occurring during the WAIM was responsible for the formation of SAN microfibers and unique crystal morphology distribution in the WAIM iPP/SAN blend part. Moreover, during the WAIM, the high cooling rate also played an important role in the formation of both phase and crystal morphologies. The preferential formation of transcrystals in the inner layer of WAIM iPP/SAN blend part could be ascribed to the strong elongation, rather than the strong shear. It was believed that the quantification of stress and temperature fields of the WAIM via numerical simulation could provide a guidence for molding high‐performance products. POLYM. ENG. SCI., 55:1698–1705, 2015. © 2014 Society of Plastics Engineers

Spatial relationship between the mental foramen and mandibular developing teeth in modern humans, chimpanzees, and hamadryas baboons.

The mental foramen (MF) of adult human mandibles is characterized by its high position and posterosuperior opening orientation, compared with that of nonhuman primates. In this study, to examine when and how such interspecies variations in MF position/orientation are manifested in the context of dental development, positional relationships between the MF and nearby forming teeth (dc, dm1, C, P3) were assessed using CT-scanned growth-series mandibles of the following three species with various MF positions and anterior dental sizes: modern humans, chimpanzees, and hamadryas baboons. Results showed that modern humans have more antero-superiorly located MF and dc than the two nonhuman samples during growth, whereas the MF and dm1 of hamadryas baboons are the most inferiorly positioned. Considering that the mandibular canal generally reaches the dc/dm1 position during infancy, the species differences in MF position can be attributed largely to the positions where the anterior deciduous teeth first appear. Specifically, the distinctive dental position of modern humans should stem eventually from the comparatively small anterior dental size. Furthermore, human MF position shifted slightly upwards with alveolar development, unlike in the nonhuman samples, accompanied by strong curvature and vertical elongation of the anterior mandibular canal. Meanwhile, the human MF shifted from a forward to a lateral/backward orientation in association with human-specific growth-related alveolar recession. The findings of this study, thus, collectively indicate that taxonomic variations in adult MF position/orientation can be interpreted partly by the positions of the surrounding developing teeth.

MP-BaP₃: a new phase from an old binary system.

A polyphosphide, mP-BaP3, with a unique two-dimensional phosphorus layer has been discovered and characterized. It crystallizes in the monoclinic space group P2₁/c with unit-cell parameters a=6.486(1), b=7.710(1), c=8.172(2) Å; β=104.72(3)°; Z=4. Its phosphorus polyanion can be derived from the strong elongation of 2/3 of the P-P bonds present in the layers of black phosphorus. The unit-cell volume of the mP-BaP3 phase is 1.4% larger than the volume of another polymorph, mS-BaP3, reported more than 40 years ago. The latter phase features the presence of one-dimensional phosphorus chains separated by Ba atoms. The differences in the structures of the phosphorus fragments in both polymorphs of barium triphosphide result in large differences in both the thermal stability of these materials as well as in their properties as evidenced by DSC, (31)P solid-state MAS NMR, UV/Vis, and surface photovoltage spectroscopies, alongside quantum-chemical calculations.

Strong Elongation Versus a Large Transverse Curvature in the Problems of High-Frequency Diffraction

The effects of the high transverse curvature and of the strong elongation on the high-frequency diffraction are studied on the examples of the perfectly conducting elliptic cylinders and spheroids with high aspect ratio.

DUST IN THE POLAR REGION AS A MAJOR CONTRIBUTOR TO THE INFRARED EMISSION OF ACTIVE GALACTIC NUCLEI

(abridged) It is generally assumed that the distribution of dust on parsec scales forms a geometrically- and optically-thick entity in the equatorial plane around the accretion disk and broad-line region - dubbed "dust torus" - that emits the bulk of the sub-arcsecond-scale IR emission and gives rise to orientation-dependent obscuration. Here we report detailed interferometry observations of the unobscured (type 1) AGN in NGC 3783 that allow us to constrain the size, elongation, and direction of the mid-IR emission with high accuracy. The mid-IR emission is characterized by a strong elongation toward position angle PA -52 deg, closely aligned with the polar axis (PA -45 deg). We determine half-light radii along the major and minor axes at 12.5 {\mu}m of (4.23 +/- 0.63) pc x (1.42 +/- 0.21) pc, which corresponds to intrinsically-scaled sizes of (69.4 +/- 10.8) rin x (23.3 +/- 3.5) rin for the inner dust radius of rin = 0.061 pc as inferred from near-IR reverberation mapping. This implies an axis ratio of 3:1, with about 60-90% of the 8-13 {\mu}m emission associated with the polar-elongated component. These observations are difficult to reconcile with the standard interpretation that most of the parsec-scale mid-IR emission in AGN originates from the torus and challenges the justification of using simple torus models to model the broad-band IR emission. It is quite likely that the hot-dust emission in NGC 3783 as recently resolved by near-IR interferometry is misaligned with the mid-IR emitting source, which also finds a correspondence in the two distinct 3-5 {\mu}m and 20 {\mu}m bumps seen in the high-angular resolution spectral energy distribution (SED). We conclude that these observations support a scenario where the majority of the mid-IR emission in Seyfert AGN originates from a dusty wind in the polar region of the AGN.

Anomalous variation of the ocean’s inertial oscillations at the Hawaii shelf

The data of acoustic Doppler profilometers placed at the edge of the steep shelf of Oahu Island, Hawaii, are analyzed for the currents. The specific character of inertial oscillations is revealed in the region: strong elongation of inertial orbits, a large amount of anomalous (cyclonic) current rotation, and sharp weakening in the divergence layer of the background (low-frequency) oscillations, the strong variation of which results in significant deviations of the effective inertial frequency from its local geographical value. It is suggested that cyclonic rotation of the inertial currents is related to a strong decrease in the effective oscillation frequency of the oceanic waves on the shelf.

Complete submergence escape with shoot elongation ability by underwater photosynthesis in African rice, Oryza glaberrima Steud.

Flooding imposes severe selection pressure on plants, principally because excess water in their surroundings deprives the plants certain basic resources such as oxygen, carbon dioxide, and light for photosynthesis. In recent years, reports of damage caused by flooding to rice plants have increased concomitantly with the expansion of rainfed lowland rice cultivation throughout the world. Strong submergence-induced elongation, a common escape mechanism, helps submerged individuals regain and retain contact with the aerobic environment. This study analyzed physiological mechanisms of escape from complete submergence by evaluating photosynthesis, photochemical reaction, and plant behavior during and after submergence in Oryza glaberrima Steud. Partially submerged plants were unaffected by excess water because their photosynthetic rate was maintained during and after submergence. Escape mechanisms, when under complete submergence, restrain shoot elongation per shoot dry weight per day during submergence (shoot elongation index). Our results demonstrate that the leaf area and shoot biomass of the submerged plants during submergence affects their post-submergence photosynthetic rate and the PSII maximum efficiency to some degree. Under deeply prolonged submergence, O. glaberrima genotypes were characterized by faster shoot elongation, anaerobic tillering, larger leaf area extension, higher photosynthetic rate, and maintenance of PSII maximum efficiency compared with Oryza sativa genotypes without an escape mechanism. O. glaberrima employs a submergence escape strategy that effectively uses stored carbohydrates for shoot elongation and leaf extension in a severely photosynthesis-limited environment under complete submergence.

Genetic parameters for fertility of dairy heifers and cows at different parities and relationships with production traits in first lactation

The objectives of this study were to estimate genetic parameters for fertility of Brown Swiss cattle, considering reproductive measures in different parities as different traits, and to estimate relationships between production traits of first lactation and fertility of heifers and first-parity and second-parity cows. Reproductive indicators were interval from parturition to first service, interval from first service to conception, interval from parturition to conception, number of inseminations to conception, conception rate at first service, and nonreturn rate at 56 d after first service. Production traits were peak milk yield (pMY), lactation milk yield, and lactation length (LL). Data included 37,546 records on heifers, and 24,098 and 15,653 records on first- and second-parity cows, respectively. Cows were reared in 2,035 herds, calved from 1999 to 2007, and were progeny of 527 AI bulls. Gibbs sampling was implemented to obtain (co)variance components using both univariate and bivariate threshold and censored linear sire models. Estimates of heritability for reproductive traits in heifers (0.016 to 0.026) were lower than those in first-parity (0.017 to 0.142) and second-parity (0.026 to 0.115) cows. Genetic correlations for fertility in first- and second-parity cows were very high (>0.920), whereas those between heifers and lactating cows were moderate (0.348 to 0.709). The latter result indicates that fertility in heifers is a different trait than fertility in lactating cows, and hence it cannot be used as robust indicator of cow fertility. Heifer fertility was not related to production traits in first lactation (genetic correlations between −0.215 and 0.251). Peak milk yield exerted a moderate and unfavorable effect on the interval from parturition to first service (genetic correlations of 0.414 and 0.353 after first and second calving, respectively), and a low and unfavorable effect on other fertility traits (genetic correlations between −0.281 and 0.295). Infertility after first calving caused a strong elongation of the lactation, and LL was negatively correlated with fertility of cows after second calving, so that LL can itself be regarded as a measure of fertility. Lactation milk yield depends on both pMY and LL, and, as such, is a cause and consequence of (in)fertility.

Variable density self consistent field study on bounded polymer layer around spherical nanoparticles

A computational study focused on the interfacial region between polymer bulk and solid surface of spherical nanoparticles is presented. Our tool is a recently developed, properly modified for curved surfaces, variable density self-consistent field method. Grafted poly(styrene) on flat or curved surfaces and physically adsorbed poly(dimethylsiloxane) macromolecular chains on silica are examined. In the poly(styrene) study the existence of a depletion layer and an associating strong elongation of the polymeric chains is observed. On the detailed investigation of poly(dimethylsiloxane)/silica interface good agreement of the numerical results with the experimental data for the dependence of the width and the structure of the rigid amorphous inter-phase on the radius of the nanoparticle is reported. Moreover, a well understood dependence of the bounded polymer layer structure on the polydispersity (mainly bipolar structures) of the polymeric sample was found. Overall, we have shown evidence for the chain immobilization in the interfacial region and found that the thickness of the interphase is sensitive to the strength of the polymer-nanoparticle interaction and strongly depends on the curvature of the surface. Based on the unique behavior of bimodal brushes in equilibrium, confirmed by our findings, we have tried to enlighten silent and unclarified polymeric characteristics, which are not experimentally observable, and point the significance of the thermodynamic factor.

The male reproductive system of Zorotypus caudelli Karny (Zoraptera): Sperm structure and spermiogenesis

Considering the overall uniformity of the morphology of Zoraptera, the structural diversity of the male genital system is remarkable. Structures related to the male reproductive system of Zorotypus caudelli differ profoundly from those of Zorotypus hubbardi. The testes are elongated rather than spherical, the seminal vesicle is apparently absent, and the deferent ducts are very long. A feature shared by these two species and other zorapterans examined is that the two accessory glands are closely adherent to each other and form a single large structure, from which the ejaculatory duct originates. This is a potential zorapteran autapomorphy. Another feature possibly present in the groundplan of the order is the strong elongation of the sperm cells. This may be connected with a reproductive strategy of males trying to avoid re-mating of females with other males after the first copulation. The extremely long and coiled spermathecal duct of Z. caudelli and other zorapteran species is possibly correlated with the sperm elongation, and both features combined may result in a sexual isolating mechanism. The short duration of mating of Zorotypus barberi and Zorotypus gurneyi suggests that the male introduces sperm into the female tract up to the opening of the spermathecal duct using their long coiled aedeagus. A thick glycocalyx around the sperm in the distal part of the deferent ducts probably protects the sperm cells during their forward progression towards the long spermathecal duct, and is removed when they reach the apical receptacle. The spermatogenesis of Z. caudelli follows a pattern commonly found in insects, but differs distinctly from that of Z. hubbardi in the number of spermatids in each sperm cyst. An unusual and possibly autapomorphic feature of Z. caudelli is a disconnection of sub-tubules A and B at the level of microtubule doublets 1 and 6 of the mature sperm cells. It is conceivable that this results in a shorter period of sperm motility. The character combination found in different zorapteran species supports the view that the sperm, a very compact functional unit, does not evolve as a unit, but like in other more complex body regions, sperm components can also be modified independently from each other. This results in different mosaic patterns of plesiomorphic and derived features in a very compact entity in different species of the very small and otherwise uniform order Zoraptera. In Z. caudelli, for instance, the bi-layered acrosome and small accessory bodies are plesiomorphic states among several others, whereas the mitochondrial derivatives and the elongate nucleus are apparently derived conditions. Other combinations likely occur in other zorapteran species. Only few but noteworthy sperm characters indicate possible phylogenetic affinities of Zoraptera. A possible synapomorphic feature, the presence of dense laminae radiating in a cartwheel array between neighbouring centriolar triplets, is shared with Phasmatodea and Embioptera. Another potential synapomorphy shared with Phasmatodea is the presence of 17 protofilaments in the tubular wall of the outer accessory microtubules.

Gluon correlations from a glasma flux-tube model compared to measured hadron correlations on transverse momentum(pt,pt)and angular differences(ηΔ,φΔ)

A Glasma flux-tube model has been proposed to explain strong elongation on pseudorapidity $\eta$ of the same-side 2D peak in minimum-bias angular correlations from $\sqrt{s_{NN}} = 200$ GeV \auau collisions. The same-side peak or "soft ridge" is said to arise from coupling of flux tubes to radial flow. Gluons radiated transversely from flux tubes are boosted by radial flow to form a narrow structure or ridge on azimuth. In this study we test the conjecture by comparing predictions for particle production, spectra and correlations from the Glasma model and conventional fragmentation processes with measurements. We conclude that the Glasma model is contradicted by measured hadron yields, spectra and correlations, whereas a two-component model of hadron production, including minimum-bias parton fragmentation, provides a quantitative description of most data, although $\eta$ elongation remains unexplained.

Deformation of an elliptical inclusion in two-dimensional incompressible power-law viscous flow

An iterative, semi-analytical solution is derived for deformation of an elliptical (in cross-section) power-law viscous inclusion within an infinite linear viscous matrix undergoing a general 2D incompressible flow. Finite-element numerical models are used to extend the analysis to that of a power-law viscous matrix. The general behaviour of a deformable elliptical inclusion is not dramatically changed by power-law viscous rheology, but the effective viscosity is now a function of the orientation and axial ratio of the inclusion. Overall, the effect is similar to a markedly increased viscosity ratio for a stronger inclusion, or a decreased ratio for a weaker inclusion, when compared to the linear viscous case. As a result, rather low reference state viscosity ratios between inclusion and matrix (e.g., 2 to 3, determined at the same effective strain rate for both materials) can produce marked differences in behaviour for the range of power-law stress exponents established experimentally for many minerals and rocks (typically 3–6). Even for very high strain within a shear zone ( γ > 100), initially nearly circular inclusions ( R < 2) can maintain low axial ratios ( R < 2–3) and widely variable orientations. These inclusions deform internally and are not rigid, but continue to rotate or oscillate without strong elongation.

Sustained Elongation of Sperm Tail Promoted by Local Remodeling of Giant Mitochondria in Drosophila

Sperm length in Drosophilidae varies from a few hundred microns to 6 cm as a result of evolutionary selection. In postcopulatory competition, longer sperm have an advantage in positioning their head closer to the egg. Sperm cell elongation can proceed in the absence of an axoneme, suggesting that a mechanism besides intraflagellar transport emerged to sustain it. Here we report that sperm elongation in Drosophila melanogaster is driven by the interdependent extension of giant mitochondria and microtubule array that is formed around the mitochondrial surface. In primary cultures of elongating spermatids, we demonstrated that the mitochondrial integrity and local dynamics of microtubules at the tail tip region are essential for uniaxial elongation of the sperm tail. Mitochondria-microtubule linker protein Milton accumulated on mitochondria near the tail tip and is required for the sliding movement of microtubules. Disruption of Milton and its associated protein dMiro, and of potential microtubule crosslinkers Nebbish and Fascetto, caused strong elongation defects, indicating that mitochondria-microtubule association and microtubule crosslinking are required for spermatid tail elongation. Mitochondria play unexpected roles in sperm tail elongation in Drosophila by providing a structural platform for microtubule reorganization to support the robust elongation taking place at the tip of the very long sperm tail. The identification of mitochondria as an organizer of cytoskeletal dynamics extends our understanding of mechanisms of cell morphogenesis.

Characterization of microstructures and interpretation of flow mechanisms in naturally deformed, fine-grained anhydrite by means of EBSD analysis

Abstract Anhydrite-rich layers within foreland fold and thrust belts are frequently observed to be the weakest horizon of the sequence. Characterizing the microstructure of anhydrite is therefore important for interpreting the larger-scale deformation history of these rocks. Two microstructures from naturally deformed, fine-grained (&lt;15 µm mean grain size) anhydrite samples from the Triassic Evaporites of the Umbria–Marche Apennines, Italy were analysed using electron backscatter diffraction (EBSD). Microstructural observations, misorientation analysis and crystallographic preferred orientation (CPO) determination were carried out on these samples. Both samples have a CPO characterized by alignment of 〈001〉 and distribution of 〈100〉 and 〈010〉 on a great circle normal to this. This anhydrite 〈001〉 ‘fibre texture’ has not been described before. Microstructure A is characterized by a moderate to weak CPO and a weak shape preferred orientation at 55° to 70° from the trace of the 〈001〉 maximum. Low-angle boundaries are revealed by misorientation analysis. A change in grain size from c . 10 to c . 7 µm corresponds to reduction in strength of CPO and reduction in the number of low-angle grain boundaries. Microstructure B is characterized by a very strong CPO. The orientation of the CPO changes between different microstructural domains. The 〈001〉 maximum is always perpendicular to the trace of a strong grain elongation and high-angle grain boundaries have misorientations close to 〈001〉, suggesting that the CPO is geometrically controlled: anhydrite grains are platy with 〈001〉 short axes. The origin of the CPO is therefore unclear but it need not relate to dislocation creep deformation. Whether or not CPO relates to dislocation creep, both samples have a high number of lower-angle grain boundaries and internal grain distortions with 〈010〉 and 〈001〉 misorientation axes. These are indicative of dislocation activity and the data are best explained by slip on either (100)[010] (dominant) and (001)[100] or a combination of these. Neither of these slip systems has been recognized before. Both microstructures are interpreted to have undergone dynamic recrystallization, and the weakening of the CPO with decreasing grain size in microstructure A is suggested to be indicative of a grain-boundary sliding mechanism becoming active. Comparison with experimental data shows that creep mechanisms involving dislocations at the observed grain sizes require the differential stress magnitudes driving deformation to be greater than c . 100 MPa.

Poly[[μ2-(1Z,N′E)-2-(1,3-benzothiazol-2-ylsulfanyl)-N′-(2-oxidobenzylidene-κ2O:O)acetohydrazidato-κ2O,N′](pyridine-κN)copper(II)

In the title compound, [Cu(C16H11N3O2S2)(C5H5N)]n, the CuII atom displays a square-pyramidal CuN2O3 coordination geometry with strong elongation in the vertex direction. The hydrazone mol­ecule is coordinated to the CuII atom in a tridentate manner in the enolic form, creating five- and six-membered chelate metallarings. The pyridine mol­ecule completes the square-planar base of the copper coordination environment. The crystal structure displays zigzag polymeric Cu—O—Cu chains along [001]. Several weak π–π inter­actions between benzothia­zole rings were found in the same direction [centroid–centroid distances = 3.7484 (16), 3.7483 (16), 3.6731 (17) and 3.7649 (17) Å].

A combinatorial screening of human fibroblast responses on micro-structured surfaces

Biomaterial surfaces structured with topographical features have been predicted to play an important role in the next generation of biomedical implants. Specific trends with regard to the influence of the topographical effect on cellular behavior are however challenging to establish due to differences in the topographical features and geometries in the various studies. Here, we demonstrate the use of a highly versatile combinatorial screening approach to identify the effect of 169 distinct surface topographies, consisting of pillars, on fibroblast proliferation and mechanical response. Altering the inter-pillar gap size of the structures revealed a significant change in fibroblast proliferation and identified obvious stress-induced changes in the cytoskeleton and focal adhesion morphology. Larger (4–6 μm) inter-pillar gap sizes reduced fibroblast proliferation and elicited a strong elongation leading to a disruption of the actin cytoskeleton anchored primarily to focal adhesions located between the pillars. Smaller (1–2 μm) inter-pillar gap sizes, on the contrary, caused the fibroblasts to proliferate comparable to cells on a non-structured surface with cells having a clear actin cytoskeleton attached to focal adhesions located mostly on top of the pillars. The approach reveals a strong correlation between the exact topographical periodicities and cellular responses such as cell proliferation, cell morphology and focal adhesion.