Bright Stripes Research Articles

Feed fluctuation of ball screw feed systems and its effects on part surface quality

Feed fluctuation plays an important role on the part surface quality during the precision machining. In this paper, an analytical electromechanical model is developed to reveal the essential characteristics of the feed fluctuation for ball screw feed system, where the feedback control and driving circuit are equivalent to a “controlled current-source” and the mechanical transmission is modeled as a two-mass system. The analytical expression of displacement fluctuation is deduced and then the characteristics of feed fluctuation are investigated. Finally the influence of feed fluctuation on machining quality is analyzed. The results show that when the frequency of torque ripple is closer to the natural frequency of feed systems, the amplitude of displacement fluctuation increases significantly while that of the torque ripple has a sharp decrease. The displacement fluctuation along the feed direction contributes to the bright and dark stripes on the surface of workpiece in a precise cylindrical turning.

First Report of Cucumber mosaic virus in Tulipa sp. in Serbia.

Tulips (Tulipa sp. L.), popular spring-blooming perennials in the Liliaceae family, are one of the most important ornamental bulbous plants, which have been cultivated for cut flower, potted plant, garden plant, and for landscaping. In May 2013, during a survey to determine the presence of Cucumber mosaic virus (CMV, Cucumovirus, Bromoviridae) on ornamentals in Serbia, virus-like symptoms, including the presence of bright streaks, stripe and distortion of leaves, and reduced growth and flower size, were observed in an open field tulip production in the Krnjaca locality (a district of Belgrade, Serbia). Disease incidence was estimated at 20%. Symptomatic tulip plants were collected and tested for the presence of CMV by double-antibody sandwich (DAS)-ELISA using commercial diagnostic kit (Bioreba, AG, Reinach, Switzerland). Commercial positive and negative controls were included in each ELISA. Of the six tulip plants tested, all were positive for CMV. In bioassay, five plants of each Chenopodium quinoa, Nicotiana tabacum 'Samsun,' and N. glutinosa were mechanically inoculated with sap from selected ELISA-positive sample (79-13) using 0.01 M phosphate buffer (pH 7). Chlorotic local lesions on C. quinoa, and severe mosaic and leaf malformations on N. tabacum 'Samsun' and N. glutinosa, were observed 5 and 14 days post-inoculation, respectively. All mechanically inoculated plants were positive for CMV in DAS-ELISA testing. For further confirmation of CMV presence in tulip, total RNAs from all ELISA-positive symptomatic tulip plants were extracted with the RNeasy Plant Mini Kit (Qiagen, Hilden, Germany). Reverse transcription (RT)-PCR was performed with the One-Step RT-PCR Kit (Qiagen) using specific primer pair CMVCPfwd and CMVCPrev (1), which flank conserved fragment of the RNA3 including the entire coat protein (CP) gene and part of 3'- and 5'-UTRs. Total RNAs obtained from the Serbian watermelon CMV isolate (GenBank Accession No. JX280942) and healthy tulip leaves served as the positive and negative controls, respectively. The RT-PCR products of 871 bp were obtained from all six samples that were serologically positive to CMV, as well as from the positive control. No amplicon was recorded in the healthy control. The amplified product which derived from isolate 79-13 was purified (QIAquick PCR Purification Kit, Qiagen), directly sequenced in both directions using the same primer pair as in RT-PCR, deposited in GenBank (KJ854451), and analyzed by MEGA5 software (4). Sequence comparison of the complete CP gene (657 nt) revealed that the Serbian isolate 79-13 shared the highest nucleotide identity of 99.2% (99% amino acid identity) with CMV isolates from Japan (AB006813) and the United States (S70105). To our knowledge, this is the first report on the occurrence of CMV causing mosaic on Tulipa sp. in Serbia. Taking into account vegetative reproduction of tulips and the large scale of international trade with tulip seeding material, as well as wide host range of CMV including a variety of ornamentals (2,3), this is a very important discovery representing a serious threat for the floriculture industry in Serbia.

On-Sky Measurements of the Transverse Electric Fields’ Effects in the Dark Energy Camera CCDs

Photogenerated charge in thick, back-illuminated, fully-depleted CCDs is transported by electric fields from the silicon substrate to the collecting well at the front gate of the CCDs. However, electric fields transverse to the surface of the CCD—with diverse origins such as doping gradients, guard rings around the imaging area of the sensor, and physical stresses on the silicon lattice—displace this charge, effectively modifying the pixel area and producing noticeable signals in astrometric and photometric measurements. We use data from the science verification period of the Dark Energy Survey (DES) to characterize these effects in the Dark Energy Camera (DECam) CCDs. The transverse fields mainly manifest as concentric rings (‘‘tree rings’’) and bright stripes near the boundaries of the detectors (‘‘edge distortions’’) with relative amplitudes of about 1% and 10% in the flat-field images, respectively. Their nature as pixel size variations is confirmed by comparing their photometric and astrometric signatures. Using flat-field images from DECam, we derive templates in the five DES photometric bands (grizY) for the tree rings and the edge distortions as a function of their position in each DECam detector. These templates can be directly incorporated into the derivation of photometric and astrometric solutions, helping to meet the DES photometric and astrometric requirements.

Transverse electric fields' effects in the Dark Energy Camera CCDs

Spurious electric fields transverse to the surface of thick CCDs displace the photo-generated charges, effectively modifying the pixel area and producing noticeable signals in astrometric and photometric measurements. We use data from the science verification period of the Dark Energy Survey (DES) to characterize these effects in the Dark Energy Camera (DECam) CCDs, where the transverse fields manifest as concentric rings (impurity gradients or ``tree rings'') and bright stripes near the boundaries of the detectors (``edge distortions'') with relative amplitudes of about 1% and 10%, respectively. Using flat-field images, we derive templates in the five DES photometric bands (grizY) for the tree rings and the edge distortions as a function of their position on each DECam detector. Comparison of the astrometric and photometric residuals confirms their nature as pixel-size variations. The templates are directly incorporated into the derivation of photometric and astrometric residuals.The results presented in these proceedings are a partial report of analysis performed before the workshop ``Precision Astronomy with Fully depleted CDDs'' at Brookhaven National Laboratory. Additional work is underway, and the final results and analysis will be published elsewhere (Plazas, Bernstein & Sheldon 2014, in prep.).

HEREDITY OF BAND PATTERN IN CLOWN FISH, Amphiprion percula

One of marine ornamental fishes which was succeeded on its breeding, from eggs production to larval and juvenile rearing at Institute for Mariculture Research and Development, Gondol was Clown fish, Amphiprion percula. In local name, the fish also known as Biak Clown fish. In culture development, the fish frequently faced the problem on color pattern which was not meet with export demand. The fish should be bright orange and thin black stripe pattern. In this experiment, analysis was conducted to understand the juvenile color variation produced from 3 pairs broodstock. Larvae and juvenile were reared in the indoor hatchery for 2-3 months,then reared at outdoor tanks for other 3-4 months. Amplification of broodstock and juvenile genoms using specific primer for pigment sequens. Parameters observed on juvenile were classified into three color pattern classes i.e., class I (thick black stripe and disperse), class II(thick black stripe), and class III (thin black stripe). Numbers of juvenile analyzed from its pair broodstock and each class were 2-3 fishes. Color perform similarity coefficient was analyzed molecularly using sequencing. Sequencing process followed: DNA isolation, amplification using gen Tyr primer, purification PCR product and finally DNA sequencing. Sequencing analyses of PCR product, after alignment showed that similarity coefficient of color pattern of class I, II, and III between broodstock and juvenile was only 50 %, and phenotipically, color pattern appeared on juvenile were different than its broodstock. The changes of color perform on Clown fish also affected by interaction between genotype and environment and feed pigment concentration.Keywords: heredity, color pattern, Tyr gene, clown fish, A. percula

Dynamic biophotonics: female squid exhibit sexually dimorphic tunable leucophores and iridocytes

Loliginid squid use tunable multilayer reflectors to modulate the optical properties of their skin for camouflage and communication. Contained inside specialized cells called iridocytes, these photonic structures have been a model for investigations into bio-inspired adaptive optics. Here, we describe two distinct sexually dimorphic tunable biophotonic features in the commercially important species Doryteuthis opalescens: bright stripes of rainbow iridescence on the mantle just beneath each fin attachment and a bright white stripe centered on the dorsal surface of the mantle between the fins. Both of these cellular features are unique to the female; positioned in the same location as the conspicuously bright white testis in the male, they are completely switchable, transitioning between transparency and high reflectivity. The sexual dimorphism, location and tunability of these features suggest that they may function in mating or reproduction. These features provide advantageous new models for investigation of adaptive biophotonics. The intensely reflective cells of the iridescent stripes provide a greater signal-to-noise ratio than the adaptive iridocytes studied thus far, while the cells constituting the white stripe are adaptive leucophores--unique biological tunable broadband scatterers containing Mie-scattering organelles activated by acetylcholine, and a unique complement of reflectin proteins.

A new species of Elachistocleis (Anura: Microhylidae) from north-western Argentina.

Elachistocleis haroi sp. nov. is described from El Algarrobal, Jujuy province, north-western Argentina. The new species is diagnosed by the dorsal pattern of mid-longitudinal bright yellow stripe from the intraocular zone, surpassing the post-cephalic transverse skin fold, to vent; dorsum grayish brown mottled with a paravertebral symmetric pattern of dark spots resembling a pine tree; and a thin regular yellow line on the posterior surface of the thighs and tibiae. The advertisement call is a long trill with an average duration of 3.18 seconds, multipulsed with a mean dominant frequency of 4.56 kHz. The tadpole is characterized by the oral dermal flaps with papillae-like edges.

Observation of the Magnetic Skyrmion Lattice in a MnSi Nanowire by Lorentz TEM

We report here the real-space observation of skyrmions and helical magnetic domains in a MnSi nanowire (NW) using Lorentz transmission electron microscopy (LTEM). The MnSi NW was thinned to a rectangular cross-section by focused-ion beam milling to reduce obstructive Fresnel fringes. Helimagnetic domains, imaged as alternating bright and dark contrast stripes with an 18 nm period, were observed to be the spontaneous magnetic ground state at 6 K, while the hexagonal skyrmion lattice (SkX) with a domain diameter of 18 nm was observed under a normal magnetic field of 210 mT. Temperature-dependent measurements reveal that the SkX is stable over a larger range in this NW system (6-35 K) compared to the narrow temperature regime of skyrmion phase in bulk MnSi (26-30 K) and thin films of MnSi (5-23 K).

Iridophores and sexual dimorphism in the squid Doryteuthis gahi (Loliginidae) from the southwestern Atlantic

Light reflecting structures (iridophores) were examined in live Doryteuthis gahi with mantle lengths (ML) between 50 and 420 mm, both during trawl surveys onboard ship and in shallow-water spawning grounds (10–15 m depth) by SCUBA divers around the Falkland Islands. Several types of iridophores were distinguished based on their shape, colour reflection and position on the body. Ventrally, silvery iridophores cover pigmented organs such as the eyeballs and ink sac and might be used for countershading the squid body. Pink iridophores (splotches) cover the whole mantle, head, fins and arm bases. Green-red iridophores on the dorsal side of the eyeballs, as well as pink splotches on the dorsal and lateral mantle, head and arm bases can be either uncovered or masked by overlaying chromatophores. Two specific bright green stripes of iridophores develop under the fins only in females with ML .80 mm; these may be involved with distant sex recognition, both in forming unisex schools and in ‘preliminary mating’ in the twilight feeding grounds located at the shelf edge. During solitary egg laying in shallow waters, females mask these green stripes almost completely using the overlying chromatophores.

Dynamical Behavior of Prewavy Pattern near Nematic–Isotropic Transition

We report new results about a type of electrohydrodynamic instability, the prewavy instability, in a homeotropic nematic liquid crystal in a high-frequency electric field. This instability is seen in the form of a series of bright and dark stripes in between two crossed polarizers. The stripe formation corresponds to the periodic modulation of the rotation angle of the director in the \(xy\)-plane with periodicity along the \(x\)-direction. The dynamical behavior of prewavy patterns near the nematic–isotropic transition is reported. We found that the isotropic phase, due to the Joule heating effect, starts to grow in the dark stripes, i.e., in the vicinity of in-plane rotation angle α = 0.

Self-organized pattern formation in helium dielectric barrier discharge cryoplasmas

Self-organized patterns appear in many biological, chemical and physical systems, including electric discharges. Under certain conditions, self-organized patterns also form in plasmas generated below room temperature. These so-called cryoplasmas have also shown promise for low-damage materials processing; however, the underlying mechanisms and experimental conditions that lead to either uniform discharges or those containing self-organized patterns are still not understood completely. Here, we investigated the formation and dynamics of self-organized patterns in dielectric barrier cryoplasmas generated at plasma gas temperatures ranging from 264 down to 7 K at a constant gas density ρ = 5 × 1019 cm−3. The electrode gap was 0.15 mm and the cryoplasmas were generated at voltages between 0.8 and 1.5 kV, at frequencies ranging from 20 to 30 kHz. The discharges were characterized by time-resolved imaging, optical emission spectroscopy and current–voltage measurements. For temperatures down to 250 K, the discharges are uniform, whereas between 250 and about 140 K, self-organized, bright filamentary patterns form. Below that temperature, the discharge regime changes again to a uniform glow and for temperatures below 20 K, different types of discharges—uniform, but also self-organized dark solitons and bright stripe patterns—are observed. The cryoplasmas show current–voltage characteristics that are similar to atmospheric pressure glow discharges and the different types of uniform or self-organized discharges are suggested to be caused by the disappearance of impurities in the plasma as the temperature is lowered, and changes in the mobilities of ion species and surface charges.

COSMIC-RAY-INDUCED FILAMENTATION INSTABILITY IN COLLISIONLESS SHOCKS

We used unprecedentedly large 2D and 3D hybrid (kinetic ions - fluid electrons) simulations of non-relativistic collisionless strong shocks in order to investigate the effects of self-consistently accelerated ions on the overall shock dynamics. The current driven by suprathermal particles streaming ahead of the shock excites modes transverse to the background magnetic field. The Lorentz force induced by these self-amplified fields tends to excavate tubular, underdense, magnetic-field-depleted cavities that are advected with the fluid and perturb the shock surface, triggering downstream turbulent motions. These motions further amplify the magnetic field, up to factors of 50-100 in knot-like structures. Once downstream, the cavities tend to be filled by hot plasma plumes that compress and stretch the magnetic fields in elongated filaments; this effect is particularly evident if the shock propagates parallel to the background field. Highly-magnetized knots and filaments may provide explanations for the rapid X-ray variability observed in RX J1713.7-3946 and for the regular pattern of X-ray bright stripes detected in Tycho's supernova remnant.

Measurement of Stress and Displacement Fields in Particle Assembly subjected to Shallow Foundation Loading via Photoelasticity Technique

본 논문의 목적은 얕은 기초 하중을 받는 입상체 내의 응력의 분포와 변위를 측정하는 광탄성 기법의 적용 방안을 제시하는 데 있다. 광탄성 측정기법은 입자 집합체의 힘 전달을 시각화하기 위해 사용 되었다. 실내 모형시험은 스틸 프레임으로 경계면을 만들고 폴리카보네이트 탄성중합체로 만들어진 이차원 원형 입자들을 적층하여 구성하였다. 광탄성 시트를 원형 입자에 코팅함으로써 힘 전달의 패턴을 밝은 빛의 줄무늬 형태로 확인할 수 있었고, 광탄성 측정 기법을 통해 접촉되어 있는 입자들에서의 주 응력차의 크기, 방향 또한 측정 할 수 있었다. 변위장은 디지털 이미지 해석 기법을 사용하여 측정 하였다. 하중 재하 초기 상태와 파괴 근처의 상태에서 서로 다른 접촉력의 분포를 정량적으로 분석하였다. 파괴 이전 단계에서 관측된 광탄성 패턴과 변위장은 접촉력 사슬의 좌굴 발생 이후 즉시 사라짐을 확인하였다. The purpose of this paper is to present an photoelasticity technique for measuring the displacement and stress distribution in particle assembly subjected to shallow foundation loading. Photoelastic measurement technique was employed to visualize the force transmission of a particle assembly. A model assembly bounded by a steel frame was built by stacking bi-dimensional circular particles made of polycarbonate elastomer. Each particle was coated by a thin photoelastic sheet so that the force transmission represented by bright light stripes can be visualized. In a contacted particle, both magnitude and orientation of principal stress difference can also be measured via the photoelasticity technique. The different distributions of the contact stresses at the initial loading and near the failure were quantitatively compared. The photoelastic patterns and displacement fields observed in the pre-failure state disappears immediately after the buckling of confined force chains.

Research on the Dark Stripes Extraction Algorithm for Measuring Diameter with Diffraction

The optical diffraction is a major means of minute diameter measurements. Since the light intensity of the diffraction fringe, mainly distributed in the central bright stripes, and that will lead to a relatively low SNR for the signal of the senior stripes. The traditional dark stripes extraction algorithm affected greatly by the noise. So this paper presents an algorithm that could effectively eliminate the gross errorcaused by the noise. Than by curve fitting the local signal of the diffraction pattern with the least square principle, the system could achieve a high measurement precision.

Scanning capacitance imaging of compressible and incompressible quantum Hall effect edge strips

We use dynamic scanning capacitance microscopy to image compressible and incompressible strips at the edge of a Hall bar in a two-dimensional electron gas (2DEG) in the quantum Hall effect (QHE) regime. This method gives access to the complex local conductance, Gts, between a sharp metallic tip scanned across the sample surface and ground, comprising the complex sample conductance. Near integer filling factors we observe a bright stripe along the sample edge in the imaginary part of Gts. The simultaneously recorded real part exhibits a sharp peak at the boundary between the sample interior and the stripe observed in the imaginary part. The features are periodic in the inverse magnetic field and consistent with compressible and incompressible strips forming at the sample edge. For currents larger than the critical current of the QHE break-down the stripes vanish sharply and a homogeneous signal is recovered, similar to zero magnetic field. Our experiments directly illustrate the formation and a variety of properties of the conceptually important QHE edge states at the physical edge of a 2DEG.

Silver–gold core-shell nanoparticles containing methylene blue as SERS labels for probing and imaging of live cells

We report on silver-gold core-shell nanostruc- tures that contain Methylene Blue (MB) at the gold-silver interface. They can be used as reporter molecules in surface- enhanced Raman scattering (SERS) labels. The labels are stable and have strong SERS activity. TEM imaging revealed that these nanoparticles display bright and dark stripe structures. In addition, these labels can act as probes that can be detected and imaged through the specific Raman signatures of the reporters. We show that such SERS probes can identify cellular structures due to enhanced Raman spectra of intrinsic cellular molecules measured in the local optical fields of the core-shell nanostructures. They also provide structural information on the cellular environment as demonstrated for these nanoparticles as new SERS-active and biocompatible substrates for imaging of live cells.

Hydrocolpos or Hematocolpos?

AJR 2012; 198:W324 0361–803X/12/1983–W324 © American Roentgen Ray Society Hydrocolpos or Hematocolpos? We congratulate Phillips et al. [1] on their instructive article in the May 2011 issue of the AJR, which highlights the important causes of lower abdomen pain in children, many of which are easily overlooked by clinicians and radiologists alike. Scenario 3 related the history of a 5-yearold girl with lower abdomen pain and was accompanied by two images from a pelvic ultrasound examination (Fig. 5 in the article). The authors described a fluid-distended vagina and diagnosed a hydrocolpos. In reviewing the relevant images, we agree that the vagina is distended with debris-laden fluid; however, the authors fail to point out that the uterus in Figure 5B is pubertal in configuration, with an echo-bright endometrial stripe. Such an appearance can only be secondary to stimulation by estrogen. The normal (nonneonatal) prepubertal uterus is small (less than 3–4 cm in length) with the fundus narrower than the cervix and no evidence of an endometrial bright stripe. If this image is indeed that of a 5-yearold girl, then further investigation for an endogenous or exogenous source of estrogen needs to be instituted; a hormone-secreting neoplasm is a possibility. Recognition of an ageappropriate uterus is vital for all who perform and interpret female pelvic imaging. We believe the images presented are more in keeping with an adolescent girl with primary amenorrhea and a diagnosis of hematocolpos. Anne Paterson Susan C. Gowdy Louise E. Sweeney Royal Belfast Hospital for Sick Children, Belfast, Northern Ireland, United Kingdom

Reverse contrast and substructures in protein micro-patterns on 3D polymer surfaces

We characterize an approach enabling protein patterning over broad polymer areas based on selective protein adsorption on surfaces of spin-cast amino-terminated polystyrene structured topographically with elastomer molds (capillary force lithography) and passivated locally against adsorption with poly(ethylene oxide)-silanes printed with flat elastomer stamps (inverted micro-contact printing). Atomic force microscopy reveals uniformity of PS-NH 2 films with stripes of grooves and elevations alternating with periodicity 4 < λ < 200 μm. Film morphologies, prior and after selective adsorption of model protein, are mapped with optical and fluorescence microscopes, respectively. The examination with the Fourier analysis shows that elevated regions of polymer relief are replicated as dark or bright stripes on fluorescent micrographs for elevations forming plateaus (>3 μm) or narrow ridges, respectively. Reverse contrast in protein micro-patterns is induced by modified relief geometry, which affects surface flux of silanes from stamp to polymer surface both within and away from contact zones of micro-contact printing. In addition, protein substructures with a fraction λ/ n of relief periodicity are observed on surfaces with elevated ridges ( n = 2) and plateaus ( n = 2 and 4). This is due to the locally modified protein adsorption with silane concentration and surface topography, respectively.

EASTERN COLLARED LIZARD

The foreground shows a glade on Stegall Mountain that was colonized by collared lizards after prescribed woodland fires were initiated. Thorny Mountain is in the background, showing the glades imbedded in the woodland matrix. The Thorny Mountain glades were colonized by lizards from Stegall Mountain after the fire management area was expanded to include Thorny Mountain and the valley between Stegall and Thorny Mountains. Photograph by Alan Templeton. The eastern collared lizard (Crotaphytus collaris collaris) lives on Ozark glades habitats of exposed bedrock imbedded in a woodland matrix. Effective fire suppression began in the 1940s in the Stegall and Thorny Mountain region of the Ozarks. The unburned woodlands became a barrier to lizard dispersal between glades, leading to extinction by 1980. Starting in 1984 we translocated lizards onto restored glades. The translocated populations persisted, but did not disperse. In 1994 woodland fires were initiated, which unleashed much dispersal. The populations underwent a dramatic transition from isolated fragments, to a nonequilibrium colonizing metapopulation, and finally to a stable metapopulation. A collared lizard hatchling. Hatchlings have a low probability of dispersal during the colonizing phase, but once a stable metapopulation has been established, ~50% of the hatchlings disperse, and they disperse long distances. All dispersal between mountains was mediated by hatchlings. This photograph also illustrates the main capture technique of noosing lizards with a dental floss noose tied to a fishing pole. Photograph by Jennifer L. Neuwald. A gravid adult collared lizard female. Female shave bright orange stripes and spots induced by hormonal changes after their eggs are fertilized. Adult females have the lowest probabilities of dispersal and the lowest dispersal distances. Photograph by Alan Templeton. Adult male collared lizards. About 25% of adult males disperse once a stable metapopulation has been established, and they disperse long distances, although they always remain on the same mountain. A male showing the more typical male coloration. This male lizard has more yellow coloration. The increase in the frequency of these yellowish males was associated with the founding of populations on Thorny Mountain by a small number of lizards dispersing from Stegall Mountain. Photographs by Alan Templeton. An adult male/female pair of collared lizards. Both males and females are territorial, but male territories typically include several female territories. Territories are aggressively defended, particularly by males against other males. Photograph by Alan Templeton. These photographs illustrate the article “The transition from isolated patches to a metapopulation in the eastern collared lizard in response to prescribed fires” by Alan R. Templeton, Hilary Brazeal, and Jennifer L. Neuwald, tentatively scheduled to appear in Ecology 92(9), September 2011. [doi: 10.1890/10-1994.1].

Synthesis of p-aminothiophenol-embedded gold/silver core-shell nanostructures as novel SERS tags for biosensing applications

We describe a novel surface-enhanced Raman scattering (SERS) tag that is based on Au/Ag core-shell nanostructures embedded with p-aminothiophenol. The Au/Ag core-shell sandwich nanostructures demonstrate bright and dark stripe structure and possess very strong SERS activity. Under optimum conditions, the maximum SERS signal was obtained with a 10 nm thick Ag nanoshell, and the enhancement factor is 3.4 × 104 at 1077 cm−1. After conjugation to the antibody of muramidase releasing protein (MRP), the Au/Ag core-shell nanostructures were successfully applied to an SERS-based detection scheme for MRP based on a sandwich type of immunoassay.