Hk Values Research Articles

Analysis of the public HARPS/ESO spectroscopic archive

Context. Magnetic activity is currently the primary limiting factor in radial velocity (RV) exoplanet searches. Even inactive stars, such as the Sun, exhibit RV jitter of the order of a few m s−1 due to active regions on their surfaces. Time series of chromospheric activity indicators, such as the Ca II H&K lines, can be utilized to reduce the impact of such activity phenomena on exoplanet search programmes. In addition, the identification and correction of instrumental effects can improve the precision of RV exoplanet surveys. Aims. We aim to update the HARPS -RVBANK RV database and include an additional 3.5 yr of time series and Ca II H&K lines (R′HK) chromospheric activity indicators. This additional data will aid in the analysis of the impact of stellar magnetic activity on the RV time series obtained with the HARPS instrument. Our updated database aims to provide a valuable resource for the exoplanet community in understanding and mitigating the effects of such stellar magnetic activity on RV measurements. Methods. The new HARPS-RVBANK database includes all stellar spectra obtained with the HARPS instrument prior to January 2022. The RVs corrected for small but significant nightly zero-point variations were calculated using an established method. The R′HK estimates were determined from both individual spectra and co-added template spectra with the use of model atmospheres. As input for our derivation of R′HK, we derived stellar parameters from co-added, high signal-to-noise ratio templates for a total of 3230 stars using the stellar parameter code SPECIES. Results. The new version of the HARPS RV database has a total of 252 615 RVs of 5239 stars. Of these, 195 387 have R′HK values, which corresponds to 77% of all publicly available HARPS spectra. Currently, this is the largest public database of high-precision (down to ~1 m s−1) RVs, and the largest compilation of R′HK measurements. We also derived lower limits for the RV jitter of F-, G-, and K-type stars as a function of R′HK.

Ca II H&K stellar activity parameter: a proxy for extreme ultraviolet stellar fluxes

Atmospheric escape is an important factor shaping the exoplanet population and hence drives our understanding of planet formation. Atmospheric escape from giant planets is driven primarily by the stellar X-ray and extreme ultraviolet (EUV) radiation. Furthermore, EUV and longer wavelength UV radiation power disequilibrium chemistry in the middle and upper atmospheres. Our understanding of atmospheric escape and chemistry, therefore, depends on our knowledge of the stellar UV fluxes. While the far-ultraviolet (FUV) fluxes can be observed for some stars, most of the EUV range is unobservable due to the lack of a space telescope with EUV capabilities and, for the more distant stars, due to interstellar medium absorption. Therefore, it becomes essential to have an indirect means for inferring EUV fluxes from features observable at other wavelengths. We present here analytic functions for predicting the EUV emission of F-, G-, K-, and M-type stars from the log R′HK activity parameter that is commonly obtained from ground-based optical observations of the Ca II H&K lines. The scaling relations are based on a collection of about 100 nearby stars with published log R′HK and EUV flux values, the latter of which are either direct measurements or inferences from high-quality FUV spectra. The scaling relations presented here return EUV flux values with an accuracy of about a factor of three, which is slightly lower than that of other similar methods based on FUV or X-ray measurements.

Decision-Making of Green Space Utilization and Protection in Urban Fringe Based on Biodiversity Trade-Off

Urbanization leads to the continuous expansion of urban built-up areas and the erosion of green space in urban fringe areas, leading to the continuous decline of biodiversity. Urban planners and managers need corresponding decision support tools to coordinate the contradiction between the utilization and protection of green space, ensure the maintenance capacity of biodiversity in green space, and realize the sustainable development of regional economy, society and ecology. Therefore, based on the Hellwig Method, this study designed a decision-making method of green space utilization and protection in urban fringe areas and applied the method to the decision simulation of single or multiple green space utilization and protection modes. In the decision simulation of a green space utilization mode, we evaluated the Hk values of one or several green space sample units, respectively. The smaller the Hk value, the smaller the influence of the green space unit on the biodiversity maintenance function of the whole green space in the region, so the green space unit can be selected first when making green space utilization planning decisions in the urban fringe. In the decision simulation of green space protection mode, the higher the Hk value of single green space sample unit combination or multiple green space sample unit combination, the greater the influence of the green space unit in the combination on the maintenance function of the overall green space biodiversity in the region. Then, when planning the green space protection in the urban fringe, the combination of such green space sample units should be given priority as the key protection and control objects. As a decision support tool for optimal scheme of green space utilization and protection in urban fringe areas, the method is practical, instructive, reasonable, operable, flexible, and universal.

Mössbauer spectroscopic study of σ-Fe68V32 compound

Sigma-phase Fe68V32 compound was investigated by means of Mössbauer spectroscopy. Spectra were recorded in a transmission mode in the temperature range of 5–427 K. They were analyzed in terms of five components associated with five lattice sites using a transmission integral method. The analysis yielded values of the hyperfine magnetic field, Hk, center shift, CSk, and the main component of the electric field gradient, Vzz(k), for each component k = A, B, C, D and E. Based on these quantities and taking into account relative contributions of the components average values of the hyperfine field, <H>, and that of the center shift, <CS>, were calculated. Temperature dependences of CSk and <CS> were used to determine Debye temperatures, TD(k) and <TD>, respectively. From the temperature dependence of <H> the record high value of the Curie temperature equal to 331(1) K was found. Magnetic moments of Fe atoms occupying particular lattice sites were estimated based on the Hk values at 5 K.

High performance dental resin composites with hydrolytically stable monomers

ObjectiveThe objectives of this project were to: 1) develop strong and durable dental resin composites by employing new monomers that are hydrolytically stable, and 2) demonstrate that resin composites based on these monomers perform superiorly to the traditional bisphenol A glycidyl dimethacrylate/triethylene glycol dimethacrylate (Bis-GMA/TEGDMA) composites under testing conditions relevant to clinical applications. MethodsNew resins comprising hydrolytically stable, ether-based monomer, i.e., triethylene glycol divinylbenzyl ether (TEG-DVBE), and urethane dimethacrylate (UDMA) were produced via composition-controlled photo-polymerization. Their composites contained 67.5wt% of micro and 7.5wt% of nano-sized filler. The performances of both copolymers and composites were evaluated by a battery of clinically-relevant assessments: degree of vinyl conversion (DC: FTIR and NIR spectroscopy); refractive index (n: optical microscopy); elastic modulus (E), flexural strength (F) and fracture toughness (KIC) (universal mechanical testing); Knoop hardness (HK; indentation); water sorption (Wsp) and solubility (Wsu) (gravimetry); polymerization shrinkage (Sv; mercury dilatometry) and polymerization stress (tensometer). The experimental UDMA/TEG-DVBE composites were compared with the Bis-GMA/TEGDMA composites containing the identical filler contents, and with the commercial micro hybrid flowable composite. ResultsUDMA/TEG-DBVE composites exhibited n, E, Wsp, Wsu and Sv equivalent to the controls. They outperformed the controls with respect to F (up to 26.8% increase), KIC (up to 27.7% increase), modulus recovery upon water sorption (full recovery vs. 91.9% recovery), and stress formation (up to 52.7% reduction). In addition, new composites showed up to 27.7% increase in attainable DC compared to the traditional composites. Bis-GMA/TEGDMA controls exceeded the experimental composites with respect to only one property, the composite hardness. Significantly, up to 18.1% lower HK values in the experimental series (0.458GPa) were still above the clinically required threshold of approx. 0.4GPa. SignificanceHydrolytic stability, composition-controlled polymerization and the overall enhancement in clinically-relevant properties of the new resin composites make them viable candidates to replace traditional resin composites as a new generation of strong and durable dental restoratives.

Using stable-hydrogen isotopes to reveal immigration in an Arctic-breeding songbird population.

BackgroundKnowledge of immigration and emigration rates is crucial for understanding of population dynamics, yet little is known about these vital rates, especially for arctic songbirds. We estimated immigration in an Arctic population of northern wheatears on Baffin Island, Canada, by the use of stable hydrogen isotopes in tail feathers (δ2HK). We assumed that δ2HK values of juvenile (hatch-year) feathers grown at the breeding grounds were representative of the local population, while those of breeding adults were indicative of where they grew their feathers during their post-breeding molt the previous year. The extent to which adult isotope values differ from those of juveniles provides an estimate of the minimum level of immigration into the breeding population.ResultsMean δ2HK values did not differ in juvenile birds between years. Breeding adult birds did not differ significantly in mean δ2HK values compared to juveniles but did differ in their respective standard deviations, reflecting a significantly wider range of isotopic signatures in adults than in juveniles. Thirty-eight percent of the δ2HK values in adults were greater ± 2 SD of the mean δ2HK values of juveniles, suggesting that at least 38 % of the breeding adults were of non-local origin, thus immigrants from elsewhere.ConclusionsAlthough the use of stable isotopes has limitations, the use of stable-hydrogen isotopic markers has the potential to contribute valuable information towards understanding immigration rates in bird populations. In our study, hydrogen isotope measurements of the feathers of northern wheatears indicated a high rate of immigration into the breeding population, which is consistent with low return rates of banded breeding adults as well as implying high emigration rates of local breeders.Electronic supplementary materialThe online version of this article (doi:10.1186/s40462-016-0081-x) contains supplementary material, which is available to authorized users.

Magnetoimpedance studies on laser and microwave annealed Fe66Ni7si7B20 ribbons

Magnetoimpedance (MI) has been investigated in the laser and microwave annealed Fe66Ni7Si7B20 ribbons. The largest MI [(MI)m] values of the ribbons annealed using laser with energies of 150, 200 and 250mJ/pulse (mJp) are 25% (at 7MHz), 30% (at 5MHz) and 21% (at 7MHz) respectively. The effect of domain wall pinning on MI was observed as field insensitive regions in the MI profiles in the ribbon annealed using 150mJp energy. Flower shaped grains in amorphous matrix in the ribbon annealed with 200mJp energy are responsible for highest (MI)m due to the least anisotropy. In the ribbons annealed for 40, 45 and 50min at 400°C using microwaves, (MI)m values are 35% (at 5MHz), 46% (at 6MHz) and 29% (at 7MHz) respectively. The large DC conductivity and the least anisotropy (smallest Hk values) in the ribbon microwave annealed for 45min at 400°C resulted in (MI)m reaching its highest value in the ribbons investigated.

A Comparison of Hong Kong and United Kingdom SF-6D Health States Valuations Using a Nonparametric Bayesian Method

ObjectivesThere is interest in the extent to which valuations of health may differ between different countries and cultures, but few studies have compared preference values of health states obtained in different countries. The present study applies a nonparametric model to estimate and compare two HK and UK standard gamble values for six-dimensional health state short form (derived from short-form 36 health survey) (SF-6D) health states using Bayesian methods. MethodsThe data set is the HK and UK SF-6D valuation studies in which two samples of 197 and 249 states defined by the SF-6D were valued by representative samples of the HK and UK general populations, respectively, both using the standard gamble technique. We estimated a function applicable across both countries that explicitly accounts for the differences between them, and is estimated using the data from both countries. ResultsThe results suggest that differences in SF-6D health state valuations between the UK and HK general populations are potentially important. In particular, the valuations of Hong Kong were meaningfully higher than those of the United Kingdom for most of the selected SF-6D health states. The magnitude of these country-specific differences in health state valuation depended, however, in a complex way on the levels of individual dimensions. ConclusionsThe new Bayesian nonparametric method is a powerful approach for analyzing data from multiple nationalities or ethnic groups to understand the differences between them and potentially to estimate the underlying utility functions more efficiently.

Validity of a portable microhardness testing system (Cariotester) for diagnosis of progression in active caries lesions

This study aimed to evaluate the validity of a portable microhardness testing system (Cariotester) for diagnosis of progression in active caries lesions by comparing data from this device and a laser fluorescence device (DIAGNOdent). Carious dentin in 12 specimens (stained clearly with a caries detector dye) was incrementally removed with a round bur at 150 μm depth intervals from the dentin surface in the direction of the pulp chamber. After each increment (total 138 sites), the Knoop hardness (HK) (evaluated with Cariotester) and DIAGNOdent (D) values were measured. HK values increased as D values decreased (regression formula: HK=0.419+238.342/D (p<0.001); coefficient of determination (R(2)): 0.602). Although DIAGNOdent quantitatively evaluates the degree of caries progression and bacterial infection status in caries lesions, our results demonstrate the validity and convenience of alternatively using microhardness measurements during caries removal to evaluate disease progression.

3D face detection using transform invariant features

A generic, transform invariant 3D facial feature detection method based on mean (H) and Gaussian (K) curvature analysis is proposed. A scale space of the HK values is constructed differently from the previous HK attempts. The 3D features are extracted from this scale space and used in a global topology, which is trained with a Gaussian model using only faces with neutral and frontal poses. The model is then tested against 1323 faces with various poses and expressions. The method is compared with four other representative algorithms from the previous literature for 3D facial feature localisation and face detection purposes.

Microwave studies of magnetic anisotropy of Co nanowire arrays

The effect of magnetocrystalline anisotropy and dipolar interactions in Co nanowire arrays is studied by ferromagnetic resonance (FMR). Microwave measurements performed by the microstripline method are reported for two series of crystalline hcp Co (with the c axis nominally perpendicular [Co(c⊥)] and parallel to the wires [Co(c∥)]) and an amorphous alloy with Co as the main component—Co94Fe5B1. Extrapolation of the high field linear part of the resonance curve (frequency versus dc field) permitted an evaluation of the effective anisotropy fields for saturated samples, as well as of the intrinsic fields HK, showing that the great differences between the three series are due to the magnetocrystalline anisotropy. The HK values for the two series of Co are discussed in terms of a model which accounts for the effect of the distributions of the c axis orientation in systems of uniaxial ferromagnets. The observed dependence of the effective anisotropy fields on the array geometry (wire length and diameter) is interpreted in terms of the interwire dipolar interactions and found to be in agreement with theoretical predictions based on a micromagnetic model. The fact that the resonance frequencies at Hdc=0 are geometry dependent shows that magnetostatic interactions are still significant at remanence. A second series of FMR experiments was performed at constant frequency (38 GHz), with the purpose of obtaining the angle dependence of the resonance field. These experiments provided an alternative method for the evaluation of the effective anisotropy field. The angle dependence of the resonance field for Co(c⊥) fitted the simplest equation for magnets with uniaxial anisotropy, obtained considering only the first order term in the expression of the magnetocrystalline energy as a function of the magnetization orientation. The same is not true for Co(c∥), which required inclusion of a second order term.

An activity catalogue of southern stars

We have acquired high-resolution echelle spectra of 225 F6-M5 type stars in the Southern hemisphere. The stars are targets or candidates to be targets for the Anglo-Australian Planet Search. Ca ii H& K line cores were used to derive activity indices for all of these objects. The indices were converted to the Mt. Wilson system of measurements and log R′HK values determined. A number of these stars had no previously derived activity indices. In addition, we have also included the stars from Tinney et al. using our Mt. Wilson calibration. The radial-velocity instability (also known as jitter) level was determined for all 21 planet-host stars in our data set. We find the jitter to be at a level considerably below the radial-velocity signatures in all but one of these systems. 19 stars from our sample were found to be active (logR′HK > −4.5) and thus have high levels of jitter. Radial-velocity analysis for planetary companions to these stars should proceed with caution.

Fe–Co–B/[Ni–Fe/Si] soft magnetic underlayer with high anisotropy field along cross-track direction on disk substrate

The origin of high anisotropy field Hk and low coercivity Hc of Fe–Co–B/Ni–Fe double-layered films with high saturation magnetization 4πMs was investigated. In-plane and out-of-plane X-ray diffractometry studies clarified that the lattice spacing of crystallites along the easy axis direction was expanded compared to that along the hard axis direction. It was confirmed that such an anisotropic residual stress caused the magnetic anisotropy energy of the double-layered film through magnetoelastic effect. Investigation of Ar gas pressure dependence of Hk suggested that the origin of the residual stress was due to the oblique incidence of sputtered particles. In order to align the orientation of magnetic anisotropy field along the cross-track direction, a Fe–Co–B/Ni–Fe double-layered soft magnetic underlayer was deposited on a rotating disk. The Fe–Co–B/Ni–Fe double-layered films on the rotating disk exhibited Hk values above 200Oe along the radial direction of the disk in the whole area of the disk.

Surface modification of the γ-TiAl alloys by the nitridation

The nitridation of Ti–47%Al–2%Nb–2%Cr (MJ12) and Ti–47%Al–2%Nb–2%Mn–0.8% TiB 2 (MJ47) was studied using purified NH 3. The flow rate of the gas was kept constant at 10 ml s −1. The nitridation process was done at temperatures of 800, 900 and 1000 °C for 36.0 ks (10 h). The alloys were then characterized using a scanning electron microscope (SEM), an X-ray diffractometer (XRD), a tribometer and a microhardness tester. The Knoop hardness (HK) values of the nitrided alloys were increased with an increase in the nitridation temperature and time. The HK values of MJ12 and MJ47 with 1000 °C nitridation for 36.0 ks were 2.1 and 1.5 times that of the non-nitrided alloys, respectively. The wear rates of MJ12 and MJ47 with 800–1000 °C nitridation were reduced by one or two orders of magnitude in comparison to the non-nitrided alloys. Hardness and wear resistance of the alloys were successfully improved by the nitridation which was in agreement with the formation of the TiN on the alloy surfaces. The SEM micrographs of the nitrided alloys showed a rough surface which could effect the wear resistance.

Hämatologische Variablen und Plasmacortisol bei Milchrindern in Laufstallhaltung nach der Kalbung und bei deren Kälbern. Effekte einiger konstanter und variabler Faktoren

Abstract. Title of the paper: Hematological variables and plasma cortisol in dairy cattle kept loose house and in their newborn calves. Effects of some constant and variable factors On 80 dairy cows (72 Holstein Friesian, 8 German Red and White, kept loose house) and on their newborn calves hemoglobin (Hb), hematocrite (Hk), mean corpuscular hemoglobin concentration (MCHC), plasma cortisol and body temperature (RT) and in calves saliva cortisol and body weight (KM) measurements were done and analysed considering lactation number (LANR) and gestation length (TD) of the cow, sex and KM of the calf, day time and type of birth (GV) and the time between parturition and measurement (ZGM). Type of birth was specified as GV1 (without assistance), GV2 (with moderate assistance by the herdsman, in some cases with mechanical support), and GV 3 (with heavy traction, most with mechanical support). The mean value of Hb and of MCHC was smaller and that of plasma cortisol was greater in calves comparing dams. In GV2 and GV3 the number of male calves was two times that of female calves. Mean Hb and Hk of cows were greater in GV2 comparing GV1 and GV3 but this difference was only significant for Hk between GV1 and GV2. In calves Hb, Hk and MCHC values became smaller from GV1 to GV3. Mean values of the differences calf-cow of Hb and Hk were significantly different between GV1, GV2 and GV3. Cows and calves with GV1 had significant smaller plasma cortisol concentrations than those with GV2 and GV3. Significant effects on calf plasma cortisol could be established for ZGM, GV, pCO2 and pH group and those on plasma cortisol of cows for ZGM and pCO2 of calf blood. Saliva cortisol had a stronger correlation with plasma cortisol in calves of group GV1 (r = 0.749) than in those calves of group GV2 (r = 0.432). The Q-Q Plots of the day time of birth and plasma cortisol concentration confirmed effects of the type of birth suggesting a role for diurnal effects. Results show effects of birth assistance measures common used in dairy cattle production on the variation of physiological variables in cows and calves and they were discussed regarding development quality and the reactivity of calves as affected by delivery.

Changes in high molecular weight kininogen levels during and after cardiopulmonary bypass surgery measured using a chromogenic peptide substrate assay.

High molecular weight kininogen (HK) is a co-factor in the blood-contact activation system. A chromogenic peptide substrate assay for HK (HKcs) has been developed in which test plasmas are mixed with diluted HK-deficient plasma and incubated with a soluble contact system activator that activates prekallikrein and factor XII. Calcium chloride, a synthetic thrombin inhibitor and a chromogenic peptide substrate for activated factor X (FXa) are then added. The FXa generated cleaves the FXa substrate releasing p-nitroanaline, which is measured photometrically. Test plasma HK values were calculated from a standard curve generated using a pooled normal plasma. Acceptable intra-assay and inter-assay precision values were obtained and levels of HK up to 200% were measurable. The assay measured HK in plasmas deficient in factor XII, prekallikrein and factor XI, was not affected by antiphospholipid antibodies and gave an acceptable correlation (r = 0.95) when normal plasmas and mixtures of HK-deficient and normal pooled plasma, calculated to give HK levels of 25 and 50%, were compared using HKcs and a HK one-stage clotting assay. The HKcs was used to measure HK levels in seven patients undergoing cardiopulmonary bypass (CPB). HK levels fell significantly during CPB (P = 0.0014) and were significantly higher (P = 0.016) 6 days after CPB, suggesting that HK may be a positive acute-phase reacting protein.

Magnetic and thermal properties of IrMn/FeTaN films

The antiferromagnetic–ferromagnetic exchange coupling between IrMn and FeTaN films has been investigated to study the effects of the exchange field on the high frequency response and the thermal stability of the anisotropy field of FeTaN. Ferromagnetic resonance, vibrating sample magnetometer, and torque measurements were used to determine the values of the unidirectional exchange bias field Hp, the uniaxial anisotropy field Hk and the interfacial energy J. Permeameter measurements to 3 GHz were used to study the effect of the exchange field on the low-frequency permeability and the high-frequency cutoff. Measurements on varying thicknesses of IrMn and FeTaN films gave Hp values from 4 to 115 Oe, Hk values from 10 to 20 Oe, Hc values from 10 to 20 Oe, and an interfacial energy J=0.075 ergs/cm2. The exchange coupling was found to have significant effects on the permeability and the thermal stability of the anisotropy.

Photometric Abundance Calibration of δ Scuti Stars Using [ITAL]hk[/ITAL] Photometry

The hk index has been used as a metallicity indicator for RR Lyrae variable stars. It is now being applied to the shorter period δ Scuti variables. Employing spectroscopic abundances of stars with published hk values and photometric indices calculated from stellar atmosphere models, a three-dimensional interpolation is used to determine [Fe/H] from intrinsic b-y, c1, and hk values. The resulting [Fe/H], log g, and Teff values for 10 δ Scuti stars are presented.

Phase transformation and magnetic properties of Sm(Co0.91−xFexCu0.07Zr0.02)z powders for bonded magnet applications

Structural and magnetic properties of Sm(Co0.91−xFexCu0.07Zr0.02)8.0, where x=0, 0.12, 0.21, 0.29, and 0.32, and Sm(Co0.64Fe0.28Cu0.06Zr0.02)z, where z ranged from 6.9 to 8.6, have been systematically investigated by x-ray powder diffraction. It was found that most of these alloys exhibit a hexagonal Th2Ni17 structure with a space group P63/mmc after an optimum solid solution treatment with rapid quench. The fully processed materials (after precipitation hardening) all exhibit a rhombohedral Th2Zn17 structure with a space group of R3̄m as the primary phase. For Sm(Co0.91−xFexCu0.07Zr0.02)8.0, the lattice parameters, a and c, and cell volume, V, increase slightly at first with increasing x, and then more sharply when x is increased above 0.28. The latter drastic increase in lattice parameters and cell volume results in a sharp decrease in the Hci, Hc, and Hk values of fully processed materials. For Sm(Co0.64Fe0.28Cu0.06Zr0.02)z, the lattice parameters, a and c, and cell volume increase slightly when z is varied from 6.8 to 7.8, then exhibit a drastic decrease when z is further increased beyond 8.0. A Br of 11.3 kG, Hci of 27 kOe, and BHmax of 30 MGOe have been obtained on Sm(Co0.63Fe0.28Cu0.07Zr0.02)8.0 after a solid solution at 1160 °C and aging at 850 °C.

On integrating the techniques of direct methods with anomalous dispersion. IV. A simplified perturbation treatment for SAS phasing.

Results from probabilistic theory for the single-wavelength anomalous-scattering (SAS) Friedel pair, two-phase structure invariants, psi H = phi H + phi-H, are used to show that the SAS three-phase structure invariants, psi HK = phi H + phi K + phi-H-K, tend to positive values that are easily estimated. Appropriate averages of the estimates provide SAS perturbation corrections in the form of positive origin shifts for the probability distribution of psi HK values and for the tangent formula. The theoretical probabilistic results are verified by empirical statistical analyses of model-calculated phases and experimentally measured structure-factor magnitudes for a small-molecule and a protein crystal structure.