Undulator Line Research Articles

Comparative studies of the complete mitochondrial genomes of four Paphia clams and reconsideration of subgenus Neotapes (Bivalvia: Veneridae)

The extreme variability of the mitochondrial (mito) genomes of bivalves makes it difficult to understand their evolutionary dynamics, given that species from different families do not share comparable features. We compared the mitogenomes from four Paphia clams (three of them were firstly sequenced) and found that mitogenome reorganization among the four congeneric species is not random but follows phylogenetic trends. Start/stop codon variations are species-correlated rather than gene-correlated, and bear useful phylogenetic information. Unique start/stop codon usage in P. euglypta and A+T content in P. amabilis indicates that these mitogenome-level characters, usually considered to be conservative features in other lineages, may not be phylogenetically evolved, but may have evolved via species-specific mitogenomic maintenance mechanisms. Variable divergence of two trnM genes in different lineages may demonstrate differences in mechanisms by which paralogous trnM genes are maintained. Sequence alignment analysis indicates that the VNTRs in the four mitogenomes have a common origin. The rationale of the subgenus Neotapes Kuroda and Habe, 1971 was supported by evidence from morphological characters, mitogenomic features, as well as phylogenetic analyses using cox1 and rrnS genes. The data suggest that the taxonomic basis of the subgenus should be “smooth surface” but not “undulated lines,” and P. textile should be classified to the Neotapes subgenus.

Numerical study of focusing lattice impact on the saturation length and power in SASE FEL

An adjustment of the electron and photon beams angular and transverse phase-space characteristics along the undulator line and the resonant interaction of the electron beam with co-propagating radiation are of basic conditions to drive the SASE-FEL process. In the real facility the SASE-FEL process can degrade due to electron beam orbit distortion caused by quadrupole misalignments in undulator section. Both those issues are in dependence of the focusing lattice arrangement in undulator section. In this paper the comparative study of the SASE-FEL process for conventional FODO focusing lattices, the undulator section arrangement with central focusing lattice and the FEL performance without external focusing system are presented. The impact of the quadrupole misalignments on the radiation saturation length and power for different focusing systems is analyzed. The numerical simulations for European XFEL project are given.

Nano-Tribological Properties of Topographically Undulated Nanocrystalline Diamond Patterns

Surface roughness-controlled nanocrystalline diamond film was fabricated as an undulated line and space pattern on a silicon oxide surface. To simulate a MEMS (Micro-/Electro-Mechanical System) and NEMS (Nano-/Electro-Mechanical System) patterned surface, 800 nm and 1 microm wide lines with a 200 nm wide space pattern were prepared on the substrate using E-beam lithography and an ESAND (Electrostatic Self-assembly of NanoDiamond) seeding layer lift-off process. Through this process, an undulated pattern of a nanocrystalline CVD diamond successfully formed by a conventional micro crystalline diamond growth system. The roughness of the deposited surface was controlled by regulating the size of the seeding nanodiamond particles. Crushing of the nanodiamond aggregates and dispersion of the nanodiamond solution was performed in an attrition milling system. An AFM (Atomic Force Microscopy) probe was used for the wear test and surface profiling of nanocrystalline diamond coatings. 2-D friction coefficient mapping by LFM (Lateral Force Microscopy) scanning showed a low friction coefficient (< 0.1) on the line-patterned diamond surface, and a higher friction coefficient (< 0.3) on a narrow area adjacent to the undulated pattern edges. With prolonged LFM scanning, the high coefficient of friction was reduced to less than 0.1. The bonding status of the nanocrystalline diamond was analyzed with Raman spectroscopy.

Ultrasonographic examination of the small intestine, large intestine and greater omentum in 30 Saanen goats

The small and large intestine of 30 healthy Saanen goats were examined ultrasonographically using a 5.0 MHz-linear transducer. The goats were examined on the right side, from the eighth rib to the caudal aspect of the flank. The small and large intestine could be easily differentiated. The descending duodenum could be imaged in 19 goats, and the jejunum and ileum seen in all goats. The jejunum and ileum were most often seen in cross-section and rarely in longitudinal section in the ventral region of the right flank. The intestinal contents were usually homogenously echoic, and active motility was observed in all the goats. The diameter of the small intestine was 0.8-2.7 cm (1.6 [0.33] cm). The spiral ansa of the colon was imaged in all the goats, and in 21 the caecum was also seen. Both these sections of large intestine were most commonly seen in the dorsal region of the right flank. The spiral ansa of the colon was easily identified by its spiral arrangement of centripetal and centrifugal gyri, which had a garland-like appearance. Because of intraluminal gas, only the wall of the colon closest to the transducer could be imaged. The diameter of the spiral colon ranged from 0.8 to 2.0 cm (1.1 [0.24] cm). Usually only the wall of the caecum closest to the transducer could be imaged and it appeared as a thick, echoic, slightly undulating line. The greater omentum could be seen in all the goats.

Cholesteric blue phases: effect of strong confinement

After an overview of cholesteric blue phases, we review our recent numerical studies on possible defect structures when blue phase I (BP I) is confined in a thin cell composed of two parallel surfaces imposing homeotropic anchoring. The cell thickness is of the order of the unit cell dimension of the bulk cubic BP I. We find several structures of disclination lines which, to our knowledge, have never been discussed in the field of liquid crystals as equilibrium structures. Those structures include a parallel array of double helix disclination lines, and two parallel arrays of undulating disclination lines almost (but not exactly) perpendicular to each other. A first-order transition between those two structures is possible, and the similarity between them is discussed.

How to Define Variation of Physical Properties Normal to an Undulating One-Dimensional Object

One-dimensional flexible objects are abundant in physics, from polymers to vortex lines to defect lines and many more. These objects structure their environment and it is natural to assume that the influence these objects exert on their environment depends on the distance from the line object. But how should this be defined? We argue here that there is an intrinsic length scale along the undulating line that is a measure of its stiffness (i.e., orientational persistence), which yields a natural way of defining the variation of physical properties normal to the undulating line. We exemplify how this normal variation can be determined from a computer simulation for the case of a so-called bottle-brush polymer, where side chains are grafted onto a flexible backbone.

POLFEL - Free Electron Laser in Poland

Free electron laser in Poland ? POLFEL is a coherent light source of the IV th generation, characterized by very short pulses in the range of 10-100fs, of big power 0,2GW and UV wavelength of 27nm of average power 1W, with effective high power third harmonic of 9nm. The laser consists of a linear superconducting accelerator 100m in length, undulator and experimental lines. It generates a monochromatic and coherent radiation and can be tuned from THz range to UV. The linac works in quasi-CW or real-CW mode. It is planned by XFEL-Poland consortium as a part of the ESFRI priority EuroFEL infrastructure collaboration network, part of the ERA

Evaluation of the relationship between maize yield spatial and temporal variability and different topographic attributes

Maize yield data were collected in seven agricultural fields irrigated by centre-pivot irrigation systems, in Southern Portugal, from 2002 to 2004. These data were then correlated with different primary and secondary topographic attributes. The attained correlation coefficients were used to evaluate the relationship between yield spatial variability and each individual topographic attribute. In this three-year period applied water was always lower than crop water requirements. The increase of applied water in 2004 resulted in an improvement in average yield and especially in yield spatial stability. Average yield showed a strong dependency on topography, with high correlation coefficients between yield and elevation and slope. It presented also a high correlation with topographic indices that reflect field water availability, such as the wetness index and distance to flow accumulation lines (DFL). The DFL index was the topographic index with higher correlation coefficients with yield. The negative coefficients of correlation between yield and DFL, attained in most fields in the three-year study period, show that, in general, yield increases with the decrease of DFL, i.e. , with the increase of water availability. In undulating land areas flow lines are very abundant, which means that, in these conditions, the DFL index can be a good tool to evaluate yield spatial variability.

Utility of novel electrocardiogram-lead system from cardiac surface using telemetry systems in free-moving dog

( Experiment 1) BS and CS ECGs of undosed dogs were recorded and compared in terms of various factors such as commingling of noise (electromyogram etc.) resulting from an animal's movement and deviation of the axis of the heart, irregularly undulating base line, and waveform change due to an animal's posture.

LCLS undulator—recent developments: Undulator tapering to compensate for particle energy loss (simulations, continuous case). First article measurements and tuning

Computer simulations using a continuous change in particle energy are an important tool in improving the performance at the final stage of the Linac Coherent Light Source (LCLS) undulator line. Changes in the particle energy cause the break length between undulator segments to no longer be optimized. Radiation losses less than 0.1%/undulator segment can be easily compensated by adjustment of an undulator deflection parameter K. For higher losses, up to 0.4%, adjustment of K can still be compensated, but careful optimization is required. Compensating for losses greater than 0.4% requires tapering of the field within the undulator segment. The LCLS undulator segments are in mass production at this time. The first two undulators for the LCLS project were delivered to the APS magnetic measurement facility. They have already been tuned, and meet all requirements for the LCLS free-electron laser (FEL). The final results of this tuning will be presented, with emphasis on the FEL-specific requirements. A systematic zero shift in the Sentron [ 〈http://www.sentron.ch/〉. [1]] 2-axis Hall probe was discovered, which required correction in order to obtain the proper field integrals.

Periodic travelling wave solutions of a curvature flow equation in the plane

In the plane, we consider a curvature flow equation in heterogeneous media with periodic horizontal striations, the periodicity in space is expressed by periodic (in vertical direction) coefficients in the equation. We prove the existence and uniqueness of a curve which travels upward periodically with an average speed. At each time, the graph of the curve is a periodic undulating line at a finite distance from a straight line with a given inclination angle. We also show that the average speed depends on the inclination angle monotonously. Moreover, for homogenization problem as the spatial period tends to zero, we estimate the average speed by the inclination angle and some means of the periodic coefficients.

A new species of Coelopleurus (Echinodermata: Echinoidea: Arbaciidae) from New Caledonia

Coelopleurus exquisitus sp. nov. Coppard &amp; Schultz, 2006 occurs at depths of 240 m to 520 m off of New Caledonia in the South Pacific. This new species is distinctive in having large naked interambulacral median regions that are purple with an undulating lavender line, in conjunction with highly curved primary spines that are banded red and pale-green on their dorsal surface for three quarters of the distal length, pointed secondary spines and aboral ophicephalous pedicellariae that have constricted valves.

High-resolution accelerator alignment using x-ray optics

We propose a novel alignment technique utilizing the x-ray beam of an undulator in conjunction with pinholes and position-sensitive detectors for positioning components of the accelerator, undulator, and beam line in an x-ray free-electron laser. Two retractable pinholes at each end of the undulator define a stable and reproducible x-ray beam axis (XBA). Targets are precisely positioned on the XBA using a pinhole camera technique. Position-sensitive detectors responding to both x-ray and electron beams enable direct transfer of the position setting from the XBA to the electron beam. This system has the potential to deliver superior alignment accuracy ($1\char21{}3\text{ }\ensuremath{\mu}\mathrm{m}$) for target pinholes in the transverse directions over a long distance (200 m or longer). It can be used to define the beam axis of the electron-beam\char21{}based alignment, enabling high reproducibility of the latter. This x-ray\char21{}based concept should complement the electron-beam\char21{}based alignment and the existing survey methods to raise the alignment accuracy of long accelerators to an unprecedented level. Further improvement of the transverse accuracy using x-ray zone plates will be discussed. We also propose a concurrent measurement scheme during accelerator operation to allow real-time feedback for transverse position correction.

Structure and Stability of Silica Particle Monolayers at Horizontal and Vertical Octane−Water Interfaces

Monolayers of silica particles at horizontal and vertical octane-water interfaces have been studied by microscopy. It is found that their structure and stability depend strongly on the particle hydrophobicity. Very hydrophobic silica particles, with a contact angle of 152 degrees measured through the water, give well-ordered monolayers at interparticle distances larger than 5 particle diameters which are stable toward aggregation and sedimentation. In contrast, monolayers of less-hydrophobic particles are disordered and unstable. Two-dimensional particle sedimentation has been observed in the case of vertical monolayers. The results have been analyzed with a simple two-particle model considering the sedimentation equilibrium as a balance between the long-range electrostatic repulsion through the oil, the gravity force, and the capillary attraction due to deformation of the fluid interface around particles. The value of the charge density at the particle-octane interface, 14.1 muC/m(2), found for the most hydrophobic particles is reasonable. It drastically decreases for particles with lower hydrophobicity, which is consistent with the order-disorder transition in monolayer structure reported by us before. The pair interactions between particles at a horizontal octane-water interface have been analyzed including the capillary attraction due to undulated three-phase contact line caused by nonuniform wetting (the contact angle hysteresis). The results are in agreement with the great stability of very hydrophobic silica particle monolayers detected experimentally, even at low pH at the point of zero charge of the particle-water interface, and with the aggregated structure of hydrophilic particle monolayers.

Interactions between particles with an undulated contact line at a fluid interface: Capillary multipoles of arbitrary order

A colloidal particle adsorbed at a fluid interface could have an undulated, or irregular contact line in the presence of surface roughness and/or chemical inhomogeneity. The contact-line undulations produce distortions in the surrounding liquid interface, whose overlap engenders capillary interaction between the particles. The convex and concave local deviations of the meniscus shape from planarity can be formally treated as positive and negative “capillary charges,” which form “capillary multipoles.” Here, we derive theoretical expressions for the interaction between two capillary multipoles of arbitrary order. Depending on the angle of mutual orientation, the interaction energy could exhibit a minimum, or it could represent a monotonic attraction. For undulation amplitudes larger than 5 nm, the interaction energy is typically much greater than the thermal energy kT. As a consequence, a monolayer from capillary multipoles exhibits considerable shear elasticity, and such monolayer is expected to behave as a two-dimensional elastic solid. These theoretical results could be helpful for the understanding of phenomena related to aggregation and ordering of particles adsorbed at a fluid interface, and for the interpretation of rheological properties of particulate monolayers. Related research fields are the particle-stabilized (Pickering) emulsions and the two-dimensional self-assembly of microscopic particles.

Undulator for the LCLS project—from the prototype to the full-scale manufacturing

The design of a new hybrid-type undulator with a fixed gap of 6.4 mm, a period of 30 mm and a length of 3.4 m is presented. The fractional variations in deflection parameter K between segments of 130.4-m-long undulator line for the Linac Coherent Light Source (LCLS) must be ⩽1.5×10 −4. Major design features and their choices are discussed. Lessons learned while working with this prototype are critical for successful project execution. Although the prototype undulator met all of the LCLS specifications, development continued in order to simplify the system. A canted-pole geometry was adopted, which allows the K value to be changed by lateral translation of the entire undulator segment. The prototype undulator was subsequently modified to test the canted-pole concept. Magnetic measurements demonstrated that the undulator with canted poles meets all LCLS specifications and is more cost effective to implement.

Variable height slot-outcoupling for the compact UH THz-FEL

The quest for tunable, compact coherent radiation sources in the THz region of the electro-magnetic spectrum is growing and stimulating further developments and research activities in this area. The THz-FEL Group of the University of Hawaii (UH) pursues the concept of minimizing size and cost of a recirculating-beam electrostatic accelerator THz-FEL. The system employs a low voltage (1.7 MeV) pelletron accelerator in conjunction with a short period ( λ u=8 mm) hybrid undulator and miniature beam line components. The continuous tunability offered by the system over a spectral range between 230 and 640 μm necessitates a broad-band outcoupling mechanism. Holes on the axis in resonator mirrors have been previously employed in long wavelength FELs as a means to couple out optical radiation from the cavity. The UH THz-FEL adopted a parallel plate waveguide resonator design introducing a height adjustable slot-aperture on one of the cylindrical metal mirrors. Based on the mode-matching method employed in treating waveguide discontinuities, we examine the characteristics of the chosen outcoupling mechanism and its influence on the intracavity optical fields.

Consideration on the BPM alignment tolerance in X-ray FELs

The effects of the trajectory error on the FEL amplification process are studied analytically and numerically in order to estimate the alignment tolerance of the beam position monitor (BPM) installed in the undulator line of the SASE-based FEL. Analytical investigations show that an angle error on the electron beam disturbs the FEL amplification process by two mechanisms: one is a decrease in radiation efficiency, and the other is smearing of microbunch. Simple formulae to denote these two effects are derived, and a critical angle is introduced as a criterion for the single kick error to be allowed. Then, numerical simulations are performed to estimate the tolerance of the BPM alignment to be required practically. These are in good agreement with the results of the analytical investigations.

Injection of Magnetic Energy and Magnetic Helicity into the Solar Atmosphere by an Emerging Magnetic Flux Tube

We present a detailed investigation of the dynamical behavior of emerging magnetic flux using three-dimensional MHD numerical simulation. A magnetic flux tube with a left-handed twist, initially placed below the photosphere, emerges into the solar atmosphere. This leads to a dynamical expansion of emerging field lines as well as an injection of magnetic energy and magnetic helicity into the atmosphere. The field-aligned distributions of forces and plasma flows show that emerging field lines can be classified as either expanding field lines or undulating field lines. A key parameter determining the type of emerging field line is the aspect ratio of its shape (the ratio of height to footpoint distance). The emergence generates not only vertical but also horizontal flows in the photosphere, both of which contribute to injecting magnetic energy and magnetic helicity. The contributions of vertical flows are dominant at the early phase of flux emergence, while horizontal flows become a dominant contributor later. The emergence starts with a simple dipole structure formed in the photosphere, which is subsequently deformed and fragmented, leading to a quadrupolar magnetic structure.

Fractal Design Strategies for Enhancement of Knowledge Work Environments

Converging lines of research suggest a deep linkage between cognitive and emotional processes and settings displaying a rich visual fractal structuring in the 1.3–1.5 dimensional range. Reanalysis of a previous empirical study on interior design inducing reduction of performance stress from knowledge work suggests that this fractal dimensionality of a cabin panel surface pattern was the key environmental modification affecting subjects. in natural environments, fractal dimensionality in this range is most often associated with sinuous watercourses, undulating horizon lines and branching tree structures, all of which had high survival value for human ancestors in our evolutionary history. Other empirical research indicates that cognitive performance associated with visual search and access to working memory can be improved by inducing a ‘convergence to pattern’ of fractal environmental structure and the neural processes to which it seems particularly attuned. These in turn imply significant fractal design enhancements for work settings which are either semi-isolated and/or confined for technology/health/security reasons, or habitats in remote and harsh environments.