Fiber Spacing Research Articles

Nielsen equivalence and trisections

The goal of this paper is to construct distinct trisections of the same genus on a fixed 4-manifold. For every $$k \ge 2$$ , we exhibit infinitely many manifolds with $$2^{k}-1$$ non-diffeomorphic (3k, k)-trisections. Here, the manifolds are spun Seifert fiber spaces and the trisections come from Meier’s spun trisections. The technique used to distinguish the trisections parallels a common setup for distinguishing Heegaard splittings. In particular, we show that the Nielsen classes of the generators of the fundamental group, obtained from spines of the 4-dimensional 1-handlebodies of the trisection, are isotopy invariants of the trisection. If we additionally consider the action of the automorphism group on the Nielsen classes we obtain diffeomorphism invariants. Once the invariance is established, we analyze the Nielsen classes of the spun trisections in terms of the Nielsen classes of the original Heegaard splitting, and leverage work of Lustig, Moriah, and Rosenberger on Nielsen classes of Fuchsian groups in order to distinguish the trisections.

Higher dimensional elliptic fibrations and Zariski decompositions

We study the existence and properties of birationally equivalent models for elliptically fibered varieties. In particular these have either the structure of Mori fiber spaces or, assuming some standard conjectures, minimal models with a Zariski decomposition compatible with the elliptic fibration. We prove relations between the birational invariants of the elliptically fibered variety, the base of the fibration and of its Jacobian.

Two-dimensional dose distribution measurement based on rotational optical fiber array: A Monte Carlo simulation study

Quality assurance is particularly important for modulated radiotherapies which improve dose conformity and involve complex processes of dose delivery. This work proposes a dose measurement method based on a rotational optical fiber array and the Cherenkov effect as an alternative pretreatment quality assurance method. Monte Carlo simulation toolkit Geant4 is used to study the accuracy and influencing factors of this method. Four different shapes of radiation field are designed to explore the influence of different reconstruction algorithms, fiber spacing, rotation angles, and radiation types on the accuracy of dose field measurement. The results show that the difference between the reconstructed dose field and the reference dose field is within 8% under the irradiation of uniform radiation field. To obtain high-precision reconstructed images, the fiber spacing should be within 2 mm, and at least 60 angles of projection data should be acquired when the fiber array is rotated 180°. In conclusion, the proposed new method using a rotating fiber array can reconstruct the radiation field distribution rapidly, and provides accurate information on the shape and intensity distribution of the radiation field. Further studies are needed to improve the accuracy and feasibility in real clinical practice.

Selective Conversion of Carbon Dioxide to Formate with High Current Densities

Selective conversion of CO2 to formate with high current densities is highly desirable but still challenging. Copper hollow fibers with interconnected pore structures were fabricated via a facile method and used as a stand-alone cathode for highly efficient electrochemical reduction of CO2 to formate. Our studies revealed that delivering the reactant CO2 gas to the inner space of the hollow fiber could build up a higher CO2 partial pressure in the pores and presumably reduce the concentration of H[Formula: see text] from the electrolyte to effectively suppress the major competing reaction, hydrogen evolution reaction (HER), from 46.9% faradaic efficiency (FE) to 15.0%. A high selectivity for CO2 reduction to formate with a maximum FE of 77.1% was achieved with a high current density of 34.7[Formula: see text]mA cm[Formula: see text], which is one of the highest FEs on Cu-based materials. Mechanistic studies suggest that the abundant active sites along with the unique crystal facets induced by the high pressure of CO2 at the pore surface in the “gas in” mode are attributed to the superior electroactivity and selectivity for the CO2 reduction to formate. The Cu hollow fiber electrodes exhibit an outstanding long-term stability at high current density, showing great potential for large-scale practical applications.

Space and structure activation of collagen fiber for high efficient capture iodine in off-gas

High efficiency capture of radioactive iodine-129 (129I) is of great significance in spent fuel treatment. In this study, we report a new method of space and structure activation for collagen fiber (CF) using strong alkali NaOH under ultrasonic-assisted to obtain activated collagen fiber (ACF) with active spatial structure and functional group. The as-prepared material was used for the capture of volatile iodine. The results show that the structure and morphology of ACF were characterized, indicating that the interchain hydrogen bonds were destroyed and the three-strand helix structure of CF was partially opened, resulting in more OH, CONH2 and NH2 groups on ACF surface were released. The iodine vapor capture capacity of ACF reached 1068.6 mg/g, which is higher than that of CF (428.3 mg/g) and most inorganic adsorbents. Furthermore, in iodine cyclohexane solution, the adsorption process accorded with pseudo first order kinetic and Langmuir isothermal model. With hydrogen bonds analysis and the experimental analysis of functional group shielding before and after adsorption, the mechanism is mainly the electron transfer between the OH, CONH2 and NH2 groups on ACF surface and iodine to form I3− coordination complex, indicating that CF exposed more beneficial iodine capture groups after alkali activation. Therefore, ACF is an efficient adsorption material for capturing radioactive iodine in spent fuel treatment off-gas.

Constitutive model of steel fiber reinforced concrete by coupling the fiber inclining and spacing effect

This study aims to establish a new constitutive model considering the fiber spacing and inclining effect for steel fiber reinforced concrete (SFRC) with high fiber content. To consider the influence of the fiber spacing, the fiber group effect factor is proposed for revising the reinforcement effect, and the critical fiber volume fraction is determined as 4.58%. Moreover, the fiber inclined effect factor is established by coupling the snubbing and matrix spalling effect factors, with the optimal inclining angle calculated as 32 degrees. The proposed constitutive model is introduced into Abaqus by the Umat of Fortran code, and the finite element models are established to simulate the tensile and flexural tests of SFRC. The results show that as for the tensile test of SFRC, as the fiber volume increased from zero to 7%, and 10%, the peak stress increased as high as 2.2, and 3.8 times and the strain at the peak point increased 2 and 3.5 times; and under the four-point bending test of SFRC, the toughness index has been greatly improved and reach 36. By comparing with the experimental results, it can be obtained that the proposed constitutive model is feasible for exploring the mechanical property of SFRC.

Birational geometry of singular Fano double spaces of index two

We describe the birational geometry of Fano double spaces of index 2 and dimension with at most quadratic singularities of rank , satisfying certain additional conditions of general position: we prove that these varieties have no structures of a rationally connected fibre space over a base of dimension , that every birational map onto the total space of a Mori fibre space induces an isomorphism of the blow-up of along , where is a linear subspace of codimension 2, and that every birational map of onto a Fano variety with -factorial terminal singularities and Picard number 1 is an isomorphism. We give an explicit lower estimate, quadratic in , for the codimension of the set of varieties that have worse singularities or do not satisfy the conditions of general position. The proof makes use of the method of maximal singularities and the improved -inequality for the self-intersection of a mobile linear system. Bibliography: 20 titles.

Einstein Poisson warped product space

In this paper, we provide some results on Poisson manifold (M, Π) with contravariant Levi–Civita connection associated to pair (Π, g). We introduce the notion of Einstein Poisson warped product space (M = B × f F, Π, g f ) (where Π = Π1 + Π2). Moreover, we show that if M is an Einstein Poisson warped product space with nonpositive scalar curvature and compact base B, J 1 is a field endomorphism on T*B satisfies , then M is simply a Riemannian Poisson product. For a contravariant Lorentzian Poisson warped space (M = B × f F, g, Π) (where ) one can determine contravariant Einstein equations and the cosmological constant Λ corresponding to the contravariant Einstein equation G = −Λg. Moreover, it is shown that Einstein equation G = −Λg, induces the contravariant Einstein equation with cosmological constant Λ F on fiber space (F, g F , Π F ).

Extrapolation of operator-valued multiplication operators

We study the construction of extrapolation spaces of operator-valued multiplication operators on Bochner L p -spaces by means of L p -fiber spaces.

A Menagerie of SU(2)-Cyclic 3-Manifolds

Abstract We classify $SU(2)$-cyclic and $SU(2)$-abelian 3-manifolds, for which every representation of the fundamental group into $SU(2)$ has cyclic or abelian image, respectively, among geometric 3-manifolds that are not hyperbolic. As an application, we give examples of hyperbolic 3-manifolds that do not admit degree-1 maps to any Seifert Fibered manifold other than $S^3$ or a lens space. We also produce infinitely many one-cusped hyperbolic manifolds with at least four $SU(2)$-cyclic Dehn fillings, one more than the number of cyclic fillings allowed by the cyclic surgery theorem.

Silkworm-inspired electrohydrodynamic jet 3D printing of composite scaffold with ordered cell scale fibers for bone tissue engineering

The combination of biomimetic and 3D printing has created novel opportunities for the manufacture of 3D engineered materials. A sub-microscale E-Jet 3D printing method, inspired by the dehydration and protein enrichment process of silkworm, was developed to fabricate composite bone tissue scaffold with the characteristics of controllability, fast and inexpensive. By applying the resultant effects of thermal field and flow field to low viscous composite ink, the concentration gradient biopolymer ink was obtained near the needle tip, mimicking the advanced dehydration of natural spinning apparatus. After electrical shearing force were applied on concentration gradient ink, a stable and fine jet formed. Various printing modes (droplet, continuous fiber) and structure resolutions were achieved by adjusting local solvent evaporation. Thin film, high resolution 2D structures, high aspect ratio well-bonding 3D structures were fabricated. The printed result showed that a 100 μm-sized needle could be employed directly to print patterning down to 800 nm. The printed composite scaffold with controllability of fiber size and space has been proved the feasibility as a medium for bone tissue regeneration. It can be estimated that the novel biomimetic E-Jet 3D printing technique is a new and promising way for bone tissue repairing.

Digital Measurement of the Diameter of the Collagen Fibers by Transmission Electron Microscopy for Diagnosis of Ehlers-Danlos Syndrome-Like in Small Animals

Background: Ehlers-Danlos-Like Syndrome (EDS) is a rare disease in small animals, whose diagnosis is based on the clinical findings and histopathological examination. The definitive diagnosis may require transmission electron microscopy. Despite this, the ultrastructural changes are poorly described in the literature. The aim of the present study is to describe the ultrastructural findings of collagen fibers and fibroblasts present in the dermis of two animals with EDS, and to evaluate the digital measurement of the diameter of the collagen fibers by transmission electron microscopic images.Cases: Two animals were evaluated with EDS by transmission electron microscopy. The first animal was an 1-year-old mixed breed female cat, due to spontaneous skin laceration, increased skin elasticity and an extensibility index corresponding to 25%. The second animal evaluated was a 5-month-old Golden Retriever female dog due to articular hypermobility, increased skin elasticity and an extensibility index corresponding to 16.6%. After a skin biopsy of the interscapular and lumbar regions, the samples were fixed in formalin 10% and glutaraldehyde for, respectively, histopathological examination by HE staining, and transmission electron microscopy. The histopathology of the affected cat revealed collagen fibers shortened and sometimes fragmented. The histopathology of the affected dog revealed disarranged and more eosinophilic staining collagen fibers. The collagen fibers were also of unequal sizes, shortened and slightly undulate. At the transmission electron microscopy of the affected cat was evidenced a greater spacing of the collagen fibers of variable diameters. Further this, the fibroblasts showed elongated nuclei with heterochromatic regions, which was surrounded externally by scant cytoplasm. The cytoplasm showed elongated and discrete organelles. At the transmission electron microscopy of the affected dog was evidenced a greater spacing of the collagen fibers of variable diameters. Further this, fibroblasts exhibited intense cytoplasmic vacuolization with similar appearance to that found in the dying process by autophagy. In addition, the images obtained by transmission electron microscopy were submitted to digital analysis to measure the diameter of the collagen fibers using the software Image J. For this purpose, it was obtained the average of the diameter of 10 collagen fibers in cross-section into four quadrants of 1μm each. The digital analysis of collagen fibers revealed significant alterations in the ultrastructure of collagen. In addition, it was verified cellular changes, such as the large amount of intracytoplasmic vesicles and the small amount of collagen fibers dispersed around the cells.Discussion: Microscopic abnormalities visualized by HE staining in this present study were compatible with the literature Transmission electron microscopy is fundamental to confirm the suspicion, since it revealed dermal alterations in the ultrastructure of collagen and fibroblasts. These findings indicate possible failure mechanisms of secretion and release of cellular products, as well as collagen. The digital measurement of the diameter of the collagen fibers contributed to the confirmation of the disease, since it was made randomly and reduced the subjectivity inherent of the evaluator. However, there are no studies using this method to allocate a range of significance for the diameter of collagen fibers that may be considered suggestive for the syndrome in small animals.

Effects of Fiber Stiffening to a Soft Actuator with PEDOT/PSS Electrode Films on Actuation Cycling Stability.

In this work, we fabricated a fiber-stiffened soft actuator with PEDOT/PSS films as electrode. Embedding nylon fibers in the soft actuator successfully suppressed twisting deformations, resulting in a large and persistent actuation displacement. We evaluated the effects of the fiber spacing (1, 2, 3 and 4 mm) on the displacement and assessed the actuation displacement as a function of applied voltage (0.5, 1.0 and 1.5 V) and frequency (0.2 and 1 Hz) with an actuation time of 500 s. We demonstrated that the fiberstiffened actuator with 2 mm fiber spacing exhibited steady actuation cycles (4.2 mm average displacement) in comparison with those with different spacings (1, 3, and 4 mm) and that without the fiber.

A Simple WDM-PON Architecture Together With Private Interconnected ONUs

In this paper, we present and investigate a wavelength-division-multiplexing passive optical network (WDM-PON) with symmetrical 28 Gbit/s on-off keying (OOK) access signals and 3 Gbit/s virtual private network (VPN) link between the optical network units (ONUs) simultaneously. To achieve the VPN connection, a ring-based network architecture is designed to link every ONU. Here, a direct modulation laser diode (LD) of 1311.6 nm wavelength is applied in ONU for VPN transmission to separate from PON network. In the investigation, the fiber and free space optical communication (FSO) based connections are also exploited to connect every ONU. In addition, the corresponding signal behaviors of WDM-PON and VPN networks are also analyzed and discussed.

Performance Analysis of Modulation Formats for Next Generation RoF Systems

Radio over fiber (RoF) has found to be one of the most effective communication techniques. It has the tendency to incorporate both optical fiber and free space radio paths. In this research article, importance, benefits, and applications of RoF system are discussed in detail for futuristic networks. The performance of RoF system is visualized by modulating the data with the RF signal having same frequency at both transmitter and receiver ends. Initially, the performance is checked using non-return to zero (NRZ) format and later compared with duobinary (DB) and carrier suppressed return to zero (CSRZ). Various simulations are performed which directly affect the system performance. Important parameters such as RoF link distance, data rate, transmitter power, amplifier gain, and RF signal frequency are tested. The operation is carried out at 1550 nm wavelength and 30 GHz RF frequency. System is optimized to receive the transmitted waveforms successfully. Simulations are performed in Optisystem 17.0 and MATLAB. For the analysis, the results are plotted using Q-factor and BER values.

Self-sensing cement-based sensor with carbon nanotube: Fabrication and properties – A review

Structural health monitoring is currently becoming more and more vital as it detects damage and warns users early. Since metallic sensors are less reliable and incompatible with concrete, their use in structural health monitoring is limited. This leads to the development of a nanomaterial embedded cement-based sensor. Cement composite is converted to a cement-based sensor due to its piezoresistive property. Thus, the paper examines the use of carbon nanotubes (CNT) in the development of cement-based sensors. The properties and optimum dosage of the CNT are also investigated to prepare the cement-based sensor. The manufacturing process determines the cement-based sensor properties, which is carefully examined and a manufacturing process is also proposed. The review explored that the sensor shows greater elongation capacity, compressive and flexural strength due to the CNT reinforcing capability, CNT properties, and stable interface connection with O–H bond formation. The cement-based conductive properties increase with an increase in CNT content due to contact conduction and tunnelling conduction. The analysis shows that the CNT disperses and distributes favourably in the composite through the acid treatment and sonication process, resulting in improved mechanical, conductive and piezoresistive properties. The cement composite exhibits stable piezoresistive properties with hybrid embedment due to pore filling capability, contact point increase, fiber spacing shortening and tunnelling effect. The reason for property enhancement was validated with the help of SEM investigations. This review gives a detailed insight into the material properties, sensor fabrication, mechanical, conductive and piezoresistive properties of the developed cement-based sensor.

О максимальной размерности алгебр Ли инфинитезимальных аффинных преобразований касательных расслоений с синектической связностью А.П. Широкова

The theory of tangent bundles over a differentiable manifold M be­longs to the geometry and topology of manifolds and is an intensively developing area of the theory of fiber spaces. The foundations of the theo­ry of fibered spaces were laid in the works of S. Eresman, A. Weil, A. Mo­ri­moto, S. Sasaki, K. Yano, S. Ishihara. Among Russian scientists, tangent bund­les were investigated by A. P. Shirokov, V. V. Vishnevsky, V. V. Shu­rygin, B. N. Shapukov and their students. In the study of automorphisms of generalized spaces, the question of infinitesimal transformations of connections in these spaces is of great importance. K. Yano, G. Vrancianu, P. A. Shirokov, I. P. Egorov, A. Z. Pet­rov, A. V. Aminova and others have studied movements in different spac­es. The works of K. Sato and S. Tanno are devoted to the motions and au­tomorphisms of tangent bundles. Infinitesimal affine collineations in tan­gent bundles with a synectic connection were considered by H. Shadyev. At present, the question of the motions of fibered spaces is considered in the works of A. Ya. Sultanov, in which infinitesimal transformations of a bundle of linear frames with a complete lift connection, the Lie algebra of holomorphic affine vector fields in arbitrary Weyl bundles are investi­gated. In this paper we obtain exact upper bounds for the dimensions of Lie algebras of infinitesimal affine transformations in tangent bundles with a synectic connection A. P. Shyrokov.

On-chip tunable SOI interferometer for quantum random number generation based on phase diffusion in lasers

Quantum random number generators (QRNG) derive randomness from quantum mechanical processes and therefore are considered a reliable source of randomness. However large size, high cost and instability issues due to conventional bulk, fiber or free space implementations restrict widespread use into complex systems and significantly affect the scalability and reliability of such solutions. Recently there has been a huge interest in photonic integration technologies for quantum optics in order to overcome aforementioned issues. We report demonstration of a QRNG based on phase diffusion in gain switched (GS) lasers. It produces random numbers by translating random phases of GS pulses (generated at 2.5 GHz rate) into amplitude fluctuations using a packaged on-chip silicon on insulator (SOI) tunable unbalanced Mach–Zehnder interferometer (uMZI). The 400 ps delay line in uMZI has been specially designed by using the combination of multi-mode and single mode waveguides to reduce the losses. The combination of tunable loss control (balancing), low waveguide losses and shorter delay improve interference quality and increase random number generation rates to gigabit scale. The mid-way and output monitoring ports on the chip can potentially be used for health checks to improve the long-term stability and reliability of QRNG in line with NIST recommendations for entropy source. True random numbers are extracted by offline post processing of the raw data. The extracted random numbers show low correlation coefficients and passed all NIST randomness tests achieving 10 Gb/s generation rate.

Topological Analysis of Fibrations in Multidimensional (C, R) Space

A holomorphically fibred space generates locally trivial bundles with positive dimensional fibers. This paper proposes two varieties of fibrations (compact and non-compact) in the non-uniformly scalable quasinormed topological (C, R) space admitting cylindrically symmetric continuous functions. The projective base space is dense, containing a complex plane, and the corresponding surjective fiber projection on the base space can be fixed at any point on real subspace. The contact category fibers support multiple oriented singularities of piecewise continuous functions within the topological space. A composite algebraic operation comprised of continuous linear translation and arithmetic addition generates an associative magma in the non-compact fiber space. The finite translation is continuous on complex planar subspace under non-compact projection. Interestingly, the associative magma resists transforming into a monoid due to the non-commutativity of composite algebraic operation. However, an additive group algebraic structure can be admitted in the fiber space if the fibration is a non-compact variety. Moreover, the projection on base space supports additive group structure, if and only if the planar base space passes through the real origin of the topological (C, R) space. The topological analysis shows that outward deformation retraction is not admissible within the dense topological fiber space. The comparative analysis of the proposed fiber space with respect to Minkowski space and Seifert fiber space illustrates that the group algebraic structures in each fiber spaces are of different varieties. The proposed topological fiber bundles are rigid, preserving sigma-sections as compared to the fiber bundles on manifolds.

The proatherogenic effect of high salt diet combined with focal hypoperfusion on spontaneous hypertension rat

Objective: To explore the histopathology, monocytes phenotypes and brain mRNA transcription of angiogenic and atherogenic factors preliminarily in spontaneous hypertensive rats (SHRs) fed with high salt diet and subjected to chronic focal hypoperfusion. Methods: A total of 21 SHRs were randomly assigned into SHR with normal diet (SHR-ND group, n=7), SHR fed with high salt (8%) chows (SHR-HSD group, n=14) groups. After induction of high salt diet for 20 weeks, unilateral carotid artery occlusion was applied to one half of SHR-HSD (SHR-HSD-UCAO, n=7) group for 10 weeks to mimic chronic focal cerebral hypoperfusion. The neuropathology, monocytes phenotypes and brain transcription of fibroblast growth factor (FGF-b), platelet-derived endothelial cell growth factor (PD-ECGF), angiogenin (ANG), transforming growth factor-β (TGF-β) and vascular endothelial growth factor A (VEGF-A) among three groups were compared. Results: The systolic blood pressure ((246±12) mmHg vs (220±16) mmHg, P=0.0291, 1 mmHg=0.133 kPa) and diastolic blood pressure ((189±15) mmHg vs (164±12) mmHg, P=0.0143) of SHR-HSD group were elevated significantly compared with those of SHR-ND group. Compared with normotensive Wistar-Kyoto (WKY), SHR-ND, SHR-HSD and SHR-HSD-UCAO groups demonstrated lipohyalinosis, vessel wall thickening, lumen narrowing and multiple enlarged perivascular space and diffuse disarrangement of nerve fiber and myelin vacuolation in corpus callosum pathologically. The ratio of CD11b(+) CD68(+) monocytes in peripheral blood of SHR-HSD group was higher compared with both SHR-ND and SHR-HSD-UCAO groups (P=0.000 8). The mean inflorescence index (MFI) of CD86 and CD206 showd considerable decline in SHR-HSD-UCAO group compared with those of SHR-HSD group (P=0.018 7 and 0.016 8, respectively). The CD86 MFI of CD11b+CD68+ monocytes in SHR-HSD-UCAO group was remarkably higher than that of SHR-ND and SHR-HSD groups (P=0.000 5). Compared with SHR-ND and SHR-HSD groups, the brain mRNA transcription of angiogenic factors including PD-ECGF and ANG were down-regulated (P=0.004 6 and 0.000 2, respectively), while the atherogenic factors including TGF-β and VEGF-A were up-regulated in SHR-HSD-UCAO group (P<0.000 1 and P=0.045, respectively). Conclusion: SHR-HSD-UCAO group shares the pathophysiological characteristics with advanced stage arteriosclerotic cerebral small vessel disease (aCSVD), including neuropathology, imbalanced circulating monocytes phenotypes and down-regulated angiogenic factors.