Large Fiber Research Articles

Analysis of Five Double-lined Spectroscopic Eclipsing Binaries Observed with TESS and LAMOST

Based on analysis of high-precision photometry from the Transiting Exoplanet Survey Satellite combining with spectroscopy from the medium-resolution spectra of the Large Sky Area Multi-Object Fiber Spectroscopic Telescope, we investigated five double-lined spectroscopic eclipsing binaries (TIC 0165626871, TIC 0159105847, TIC 0122446076, TIC 0349294422, and TIC 0155968973). With the help of Wilson–Devinney program, we accurately derived their absolute stellar parameters. TIC 0165626871, TIC 0159105847, and TIC 0122446076 were identified as detached binaries, while TIC 0349294422 and TIC 0155968973 were recognized as A-subtype and W-subtype W UMa-type systems, respectively. Especially, absolute parameters of four binaries except for TIC 0122446076 were obtained for the first time. TIC 0165626871 also shows light variations of out-of-eclipse phases, which are probably contributed by starspots. The light pulsations of TIC 0122446076 could originate from the primary star that is located in the classical Cepheid instability strip. Evolutionary states of all stars were also discussed.

Design of non-zero dispersion shifted fiber with large effective area based on variational method

The determination of design parameters of large effective area fiber with segmented-core profile is presented by using simple variational method to obtain the effective area, mode field diameter, and dispersion of the fiber. The designed fiber has a large effective area of 171.1 μm2 with mode field diameter, dispersion, and normalized cut off frequency of 9.7 μm, 2.85 ps/nm.km, 2.491, respectively. The results have shown that the fiber with a bending radius of 35 mm, has a very low bending loss of 0.0053 dB/km. The calculated of parameters values of designed non-zero dispersion-shifted fiber (NZDSF) have shown that with a segmented-core profile of radius 3.5 μm, with a ring width of 0.2 μm, the core effective area Aeff increases from 152.3 μm2 to 189 μm2, which in practical point of view, is an achievement to reduce the nonlinearity effects in the NZDSF as transmission medium.

Fine-grained all-fiber nonlocal dispersion compensation in the telecommunications O-band.

Nonlocal dispersion compensation between broadband nondegenerate photon pairs propagated over fiber corresponding to the ITU-T G.652D telecommunications standard was studied extensively via fine-grained measurements of the temporal correlation between them. We demonstrated near-ideal levels of nonlocal dispersion compensation by adjusting the propagation distance of the photon pairs to preserve photon timing correlations close to the effective instrument resolution of our detection apparatus (41.0±0.1ps). Experimental data indicates that this degree of compensation can be achieved with relatively large fiber increments (1km), compatible with real-world deployment. Ultimately, photon timing correlations were preserved down to 51ps±21ps over two multi-segmented 10km spans of deployed metropolitan fiber.

The Preliminary Statistical Analysis of LAMOST DR8 Low Resolution AFGK Stars

Abstract We download the Large sky Area Multi-Object fiber Spectroscopic Telescope Data Release 8 (LAMOST DR8) low resolution catalog for 6,478,063 AFGK type stars and plot the figures of effective temperature, gravitational acceleration and metal abundance. Some small and medium mass stars are evolved from pre-main sequence or main sequence stage to planetary nebula stage or white dwarf stage by the stellar evolution code MESA. We analyze the observed statistical data and model calculation results, and then obtain some basic conclusions preliminarily. Most red giant and asymptotic giant branch stars with log g less than 0.85 have poor metal abundance. Most hot A type main-sequence stars are metal-rich stars with log g from 3.5 to 4.5. The conclusions are reasonable within a certain error range. The theory of a gap area in the Hertzsprung–Russell diagram for stellar evolutions of medium mass stars is reflected in the statistical plots. The central core hydrogen burning stage and the central core helium burning stage correspond to the peak structures in the statistical plots for gravitational acceleration. The metal abundances among A, F, G and K type stars have a wide distribution. We cannot simply replace the metal abundances of these stars with the metal abundance of the Sun when doing fine research work.

Discovery of Nine Super Li-rich Unevolved Stars from the LAMOST Survey

Abstract Based on the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) medium-resolution spectroscopic survey (MRS), we report the discovery of nine super Li-rich unevolved stars with A(Li) > 3.8 dex. These objects show unusually high levels of lithium abundances, up to three times higher than the meteoritic value of 3.3 dex, which indicates that they must have experienced a history of lithium enrichment. It is found that seven of our program stars are fast rotators with v sin i > 9 km s−1, which suggests that the accretion of circumstellar matter may be the main contributor to the lithium enhancement of these unevolved stars; however, other sources cannot be excluded.

Large mode area multi segmented-trench crisscross fiber with resonance and leakage

In this paper, a multi segmented-trench crisscross fiber (STCF) is proposed. The multi STCF is designed from the segmented cladding fiber (SCF) and multi-trench fiber (MTF). A multi STCF is a SCF whose low index claddings are cut off by two layers of high index rings, then rotate the middle layer claddings. The high index rings are inserted into claddings to add the effect of resonance. The rotation of middle layer claddings makes the claddings distribution crisscross, thus restricting the excessive loss of core modes. Multi STCF is researched and compared to others four fibers with similar structures. The multi STCF has great advantages on large mode area and single-mode operation. When the bending radius is 20 cm, the multi STCF core radius can extend to 27 μm. And the mode area achieves 987 μm2 while simultaneously keeping large high order modes suppression. Multi STCF combines the resonance and leakage effects to adjust mode loss while enlarging the mode area. Besides, the fiber can also suit single-mode operation under certain heat load. This research has meaningful values on high power fiber lasers.

Objective Separation between CP1 and CP2 Based on Feature Extraction with Machine Learning

In the eighth data release (DR8) of the Large Sky Area Multi-Object Fiber Spectroscopic Telescope, more than 318,740 low-resolution stellar spectra with types from B to early F and signal-to-noise ratios >50 were released. With this large volume of the early-type stars, we tried machine-learning algorithms to search for class-one and class-two chemical peculiars (CP1 and CP2), and to detect spectral features to distinguish the two classes in low-resolution spectra. We selected the XGBoost algorithm after comparing the classification efficiency of three machine-learning ensemble algorithms. Using XGBoost followed by the visual investigation, we presented a catalog of 20,694 sources, including 17,986 CP1 and 2708 CP2, in which 6917 CP1 and 1652 CP2 are newly discovered. We also list the spectral features to separate CP1 from CP2 discovered through XGBoost. The stellar parameters (including effective temperature (T eff), surface gravity (log g), metallicity [Fe/H]), the spatial distribution in Galactic coordinates, and the color magnitude were provided for all of the entries of the catalog. The T eff for CP1 distributes from ∼6000 to ∼8500 K, while for CP2 it distributes from ∼7000 to ∼13,700 K. The log g of CP1 ranges from 2.8 to 4.8 dex, peaking at 4.5 dex, and of CP2 it ranges from 2.0 to 5.0 dex, peaking at 3.6 dex, respectively. The [Fe/H] of CP1 and CP2 are from −1.4 to 0.4 dex, and the [Fe/H] of CP1 are on average higher than that of CP2. Almost all of the targets in our sample locate around the Galactic plane.

The Apollo ATCA design for the CMS track finder and the pixel readout at the HL-LHC

The challenging conditions of the High-Luminosity LHC require tailored hardware designs for the trigger and data acquisition systems. The Apollo platform features a “Service Module” with a powerful system-on-module computer that provides standard ATCA communications and application-specific “Command Modules” with large FPGAs and high speed optical fiber links. The CMS version of Apollo will be used for the track finder and the pixel readout. It features up to two large FPGAs and more than 100 optical links with speeds up to 25 Gb/s. We study carefully the design and performance of the board by using customized firmware to test power consumption, heat dissipation, and optical link integrity. This paper presents the results of these performance tests, design updates, and future plans.

Fabrication and structure optimization of expanded polystyrene (EPS) waste fiber for high-performance air filtration

Recycling waste polymer into a high-value product is a challenge the community faces. Therefore, we presented an approach to transform expanded polystyrene (EPS) into a high-value product of air filter media using multi-input needleless electrospinning. An optimum combination of large and small fiber diameter could produce an air filter with a filtration efficiency of up to 99.4%. The high filtration efficiency followed by the low pressure drop between 48 and 58 Pa (face velocity at 5.3 cm/s) resulted in a quality factor (QF) of 0.099 Pa−1, which is as good as the QF of the conventional electrospinning-air filter. The EPS-based air filter had a hydrophobic surface suitable for making a good face mask filter. In sum, the results of this study could give a comprehensive understanding of structural modification of EPS-based air filter properties and a significant impact on the development of large-scale air filter production for the face mask.

Revisit NGC 5466 tidal stream withGaia, SDSS/SEGUE, and LAMOST

ABSTRACTBy mining the data from Gaia Early Data Release 3, Sloan Digital Sky Survey/Sloan Extension for Galactic Understanding and Exploration Data Release 16, and Large Sky Area Multi-Object Fiber Spectroscopic Telescope Data Release 8, 11 member stars of the NGC 5466 tidal stream are detected and 7 of them are newly identified. To reject contaminators, a variety of cuts are applied in sky position, colour–magnitude diagram, metallicity, proper motion, and radial velocity. We compare our data to a mock stream generated by modelling the cluster’s disruption under a smooth Galactic potential plus the Large Magellanic Cloud (LMC). The concordant trends in phase space between the model and observations imply that the stream might have been perturbed by the LMC. The two most distant stars among the 11 detected members trace the stream’s length to 60° of sky, supporting and extending the previous length of 45°. Given that NGC 5466 is so distant and potentially has a longer tail than previously thought, we expect that the NGC 5466 tidal stream could be a useful tool in constraining the Milky Way gravitational field.

Spatial beam reshaping and large-band nonlinear conversion in rectangular-core phosphate glass fibers

Here we present the ability of Nd3+-doped zinc-phosphate glasses to be shaped into rectangular core fibers. At first, the physico-chemical properties of the developed P2O5-based materials are investigated for different concentrations of neodymium oxide and core and cladding glass compositions are selected for further fiber development. A modified stack-and-draw technique is used to produce multimode large rectangular-core optical fibers. Self-guided nonlinear effects acting as spatial beam reshaping processes occurring in these newly-developed photonic structures lead to the generation of spectral broadenings in the visible and near-infrared spectral domains.Graphic

The Value-added Catalog for LAMOST DR8 Low-resolution Spectra

Abstract We present a value-added catalog containing stellar parameters estimated from 7.10 million low-resolution spectra for 5.16 million unique stars with spectral signal-to-noise ratios (S/N) higher than 10 obtained by the Large Sky Area Multi-Object Fibre Spectroscopic Telescope (LAMOST) Galactic spectroscopic surveys. The catalog presents values of stellar atmospheric parameters (effective temperature T eff, surface gravity log g, metallicity [Fe/H]/[M/H]), α-element to metal abundance ratio [α/M], carbon and nitrogen to iron abundance ratios [C/Fe] and [N/Fe], and 14 bands’ absolute magnitudes deduced from LAMOST spectra using the neural network method. The spectrophotometric distances of those stars are also provided based on the distance modulus. For stars with a spectral S/N larger than 50, precisions of T eff, log g, [Fe/H], [M/H], [C/Fe], [N/Fe], and [α/M] are 85 K, 0.098 dex, 0.05 dex, 0.05 dex, 0.052 dex, 0.082 dex, and 0.027 dex, respectively. The errors of 14 band’s absolute magnitudes are 0.16–0.22 mag for stars with a spectral S/N larger than 50. The spectrophotometric distance is accurate to 8.5% for stars with a spectral S/N larger than 50 and is more accurate than the geometrical distance for stars with a distance larger than 2.0 kpc. Our estimates of [Fe/H] are reliable down to [Fe/H] ∼−3.5 dex, significantly better than previous results. The catalog provides 26,868 unique very metal-poor star candidates ([Fe/H] ≤−2.0). The catalog would be a valuable dataset to study the structure and evolution of the galaxy, especially the solar neighborhood and the outer disk.

Large Mode Area Single Mode Fiber with a Twisted Polygon-Shaped Core

We present numerical studies on twisted polygon-shaped core fibers for achieving single mode operation with a large mode area propagation in this paper. These large mode area fibers can achieve single mode operation due to twisting-induced high losses to higher order modes and coupling higher order modes with leaky modes. A tail-like profile will appear in higher order modes when they couple with leaky modes, and the tail-like profile also indicates that these modes carry angular momentum. Numerical simulations show that twisted octagon-shaped core fiber with a core diameter of 80 μm can obtain first higher order mode losses larger than 19 dB/m while maintaining fundamental mode losses at about 0.15 dB/m. In the case of twisted heptagon-shaped core, an 80 μm diameter fiber design exists with more than 17 dB/m first higher order modes propagation losses and less than 0.14 dB/m fundamental mode losses.

Validation and Improvement of the Pan-STARRS Photometric Calibration with the Stellar Color Regression Method

Abstract As one of the best ground-based photometric data set, Pan-STARRS1 (PS1) has been widely used as the reference to calibrate other surveys. In this work, we present an independent validation and recalibration of the PS1 photometry using spectroscopic data from the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) DR7, and photometric data from the corrected Gaia Early Data Release 3 (EDR3) with the Stellar Color Regression (SCR) method. Using per band typically a total of 1.5 million LAMOST-PS1-Gaia stars as standards, we show that the PS1 photometric calibration precisions in the grizy filters are around 4 ∼ 5 mmag when averaged over 20′ regions. However, significant large- and small-scale spatial variation of magnitude offset, up to over 1%, probably caused by the calibration errors in the PS1, are found for all the grizy filters. The calibration errors in different filters are uncorrelated, and are slightly larger for the g and y filters. We also detect moderate magnitude-dependent errors (0.005, 0.005, 0.005, 0.004, 0.003 mag per magnitude in the 14–17 mag range for the grizy filters, respectively) in the PS1 photometry by comparing with the Gaia EDR3 and other catalogs. The errors are likely caused by the systematic uncertainties in the PSF magnitudes. We provide two-dimensional maps to correct for such magnitude offsets in the LAMOST footprint at different spatial resolutions from 20′ to 160′. The results demonstrate the power of the SCR method in improving the calibration precision of wide-field surveys when combined with the LAMOST spectroscopy and Gaia photometry.

Thermo-optical numerical modal analysis of multicore fibers for high power lasers and amplifiers

Lasers for modern industrial and research applications are required to provide a high average beam power and at the same time be reliable, efficient, and compact. Rare-earth doped single-mode fiber lasers are the most promising solution. Large mode area fibers are effectively used to reduce nonlinear effects and scaling up the beam power which is now bounded by thermal effects. A new cutting-edge approach to the issue involves the use of Multi-Core Fibers (MCFs), coherently combining several lower power beams into a higher power one, and thus pushing the threshold of nonlinearities and transverse mode instabilities to higher power. The amplification process involves heat generation in the doped cores due to quantum defect, which propagates radially and creates a temperature gradient across the fiber cross-section. Even though the cores are optically uncoupled, the refractive index gradient due to thermo-optical effects could cause cross-talk and core mode coupling. In this work, we numerically analyze the performances of 9-core MCFs for high power fiber lasers by taking into account the coupling and bending effects due to the heat load generated by the quantum defect between pump and laser radiation. MCFs show very low sensitivity to heat load and bending, with effectively single-mode behaviour up to 15 μm core diameter (effective area 181 μm2) and down to 35 μm pitch.

The Role of Neuropathy Screening Tools in Patients Affected by Fibromyalgia.

Fibromyalgia syndrome (sFM) is one of the most common causes of chronic pain. This study aimed to assess the presence of small and large fiber impairment in fibromyalgic patients by applying validated scores used in the screening for diabetic neuropathy. The endpoints for the study were the assessment of neuropathy prevalence in sFM patients using the NerveCheck Master (NCM), the Michigan Neuropathy Screening Instrument (MNSI), the Diabetic Neuropathy Symptom (DNS) and the Douleur Neuropathique 4 Questions (DN4). The sample was composed of 46 subjects: subjects with sFM (n = 23) and healthy controls (HC) (n = 23). The positivity rates in each group for DN4 were significantly different (p < 0.001), with a prevalence in symptomatic subjects of 56.3% (n = 9) among sFM individuals. A similar difference was also observed with the DNS total score (p < 0.001). NCM and MNSI did not disclose significant differences between the two groups. This finding seems to confirm the data regarding the prevalence of a neuropathic pain in sFM patients.

Prognostic value of cutaneous reinnervation with GAP-43 in oxaliplatin-induced neuropathy

Background and purposeOxaliplatin-induced neuropathy (OIN) implies axonal damage of both small and large sensory nerve fibers. We aimed at comparing the neurophysiological changes occurred after treatment and the capability to recovery based on histological marker of re-innervation GAP-43.Methods48 patients with cancer were assessed before and after chemotherapy (at 3 months and 12 months if available). We recorded ulnar and sural sensory nerve action potentials (SNAP), determined quantitative sensory thresholds for warm and cold (WDT, CDT), pain thresholds and collected a distal biopsy of skin to assess the intra-epidermal nerve fiber density (IENFD) with PGP9.5 and GAP-43 markers (in a subgroup of 19 patients).ResultsIncreased WDT and CDT as well as diminished IENFD at distal leg were already found in 30% of oncologic patients before treatment. After oxaliplatin, there was a significant increase in thermal thresholds in 52% of patients, and a decrease of SNAP amplitude in the sural nerve in 67% patients. IENFD was reduced in 47% and remained unchanged in 37% after oxiplatin. The density of GAP-43 + fibers and GAP-43/PGP 9.5 ratio was similar before and after treatment showing that cutaneous re-innervation is preserved despite no clinical recovery was observed after one year.ConclusionNon-selective axonal loss affects sensory fibers in OIN. However, the presence of intra-epidermal regenerative sprouts detected by GAP-43 may reduce the impact of neurotoxicity in the small fibers with long-term sequelae mostly on myelinated nerve endings. Pre-oxaliplatin GAP-43 failed to identify patients with higher risk of damage or worse recovery after treatment.

Axonal Excitability Does Not Differ between Painful and Painless Diabetic or Chemotherapy-Induced Distal Symmetrical Polyneuropathy in a Multicenter Observational Study.

ObjectiveAxonal excitability reflects ion channel function, and it is proposed that this may be a biomarker in painful (vs painless) polyneuropathy. Our objective was to investigate the relationship between axonal excitability parameters and chronic neuropathic pain in deeply phenotyped cohorts with diabetic or chemotherapy‐induced distal symmetrical polyneuropathy.MethodsTwo hundred thirty‐nine participants with diabetic polyneuropathy were recruited from sites in the UK and Denmark, and 39 participants who developed chemotherapy‐induced polyneuropathy were recruited from Denmark. Participants were separated into those with probable or definite neuropathic pain and those without neuropathic pain. Axonal excitability of large myelinated fibers was measured with the threshold tracking technique. The stimulus site was the median nerve, and the recording sites were the index finger (sensory studies) and abductor pollicis brevis muscle (motor studies).ResultsParticipants with painless and painful polyneuropathy were well matched across clinical variables. Sensory and motor axonal excitability measures, including recovery cycle, threshold electrotonus, strength–duration time constant, and current–threshold relationship, did not show differences between participants with painful and painless diabetic polyneuropathy, and there were only minor changes for chemotherapy‐induced polyneuropathy.InterpretationAxonal excitability did not significantly differ between painful and painless diabetic or chemotherapy‐induced polyneuropathy in a multicenter observational study. Threshold tracking assesses the excitability of myelinated axons; the majority of nociceptors are unmyelinated, and although there is some overlap of the "channelome" between these axonal populations, our results suggest that alternative measures such as microneurography are required to understand the relationship between sensory neuron excitability and neuropathic pain. ANN NEUROL 2022;91:506–520

Neurological manifestations of hereditary transthyretin amyloidosis: a focus on diagnostic delays

Background The recent availability of disease-modifying therapies for hereditary transthyretin amyloid (ATTRv) amyloidosis warrants urgency for earlier diagnosis and timely identification of active disease state among genetic carriers. Methods We reviewed clinical neurological data of all patients with ATTRv amyloidosis with initial visits at our amyloidosis centre between January 2016 and December 2018. We abstracted the signs and symptoms of neurological manifestations, as well as rates and patterns of diagnostic testing. Results Of 92 patients with 19 different transthyretin (TTR) mutations, 66 and 36% had symptoms attributed to large-fibre and small-fibre neuropathy, respectively, compared to 75 and 66% with corresponding examination findings. Thirty-six patients with V122I ATTR mutation had asymptomatic polyneuropathy identified on neurological examination, eight without concurrent cardiac disease. Seventy-three percent of patients had symptoms of carpal tunnel syndrome (CTS), while 26% had dysautonomia. The average delays between the onset of symptoms of large fibre neuropathy (LFN) or CTS to ATTRv amyloidosis diagnosis were 2.9 and 6.7 years, respectively. Discussion Our study found higher rates of polyneuropathy by examination than patient-reported symptoms, especially among those with V122I TTR amyloidosis, signalling asymptomatic polyneuropathy. Our findings suggest the need for routine neurological examinations and other testing for genetic carriers to achieve earlier identification of active disease state.

The Role of Typha angustifilia Fiber-Matrix Bonding Parameters on Interfacial Shear Strength Analysis.

The microbond test of natural fibers tends to produce scattered interfacial shear stress (IFSS) values. The sources of this scattering are known, but the roles they play in producing high IFSS scattering remain to be investigated. In this study, a numerical method was used to simulate microbond testing and to examine the experimental parameters in a microbond test of Typha angustifolia fiber/epoxy. Three parameters were considered: fiber diameter, fiber length embedded in the epoxy, and the distance between the vise and the specimen. The geometries were modeled and analyzed by ABAQUS software using its cohesive zone model features. There were two types of contact used in this analysis: tie constraint and surface-to-surface. The results showcased the roles of the following experimental parameters: a larger fiber diameter from a sample increased the IFSS value, a longer embedded length reduced the IFSS value, and a shorter vise–specimen distance increased the IFSS value. The IFSS scattering in the microbond test could have originated from the interaction between these parameters. Of the three parameters, only the vise–specimen distance was found to be able to be reasonably controlled. When the IFSS value was atypically large, fiber diameter and/or embedded length potentially drove the scattering. This study advises further compilation and classification of the role of each experimental parameter in modulating the IFSS value.