Absolute Zero Point Research Articles

Vrijeme sela u novom saznajnom okviru

The sociological cognitive framework of analyzing and interpreting the village time is founded on the trilogy of human, man's and humanity time. The general theoretical approach is specified on the village time with the sovereignty of human time, peasant's (man's) time and the village community (humanity) time. All three types of time have special roles, functions, importance, meaning and sense in the constitutive and regulatory establishment of the method of production of the village and social life on the whole. In their interference, the energy is manifested of the absolute zero point of the social universe time, as man's - social time. The work sketches an ideal-type form of the village time, which can be only a theoretical-methodological means revealing logos assumptions of the positive correlation of the human, peasant's and village community time. Such ideal-type form of the village of time has a cognitive and practical character. The cognitive one implies discovering the symmetry of human, peasant's and humanity time of the village community, and the causes of the appearance of asymmetry. The practical one implies the construction of a constitutive and regulatory structure of the social system of a certain society and the place and role of the village community in that society, with the aim of achieving progress as the fulfilment of fundamental human needs.

Descriptive Statistics in Medical Research

Related Article, see p 1474KEY POINT: “…the object of statistical methods is the reduction of data. A quantity of data …is to be replaced by relative few quantities which shall adequately represent the whole.” —Sir Ronald Fisher, 1922In this issue of Anesthesia & Analgesia, Meersch et al1 report results of an observational study on the role of vascular adhesion protein (VAP)-1 in the development of acute kidney injury (AKI) after cardiac surgery. The authors are commended for applying a range of descriptive statistics to characterize the patients and appropriately using and clearly reporting these statistics (Figure).Figure.: Excerpt of Table 1 from Meersch et al.1 Nominal (sex) and ordinal (ASA physical status score) data are reported as counts (absolute frequencies) and percentages (relative frequencies). Note that the numerators (counts per category per group: inside red squares) and denominators (total number of patients per group: inside blue squares) are appropriately presented. Quantitative data are reported as the mean (SD)—which is generally preferred to mean ± SD—or as the median with the Q1, Q3 values. ASA indicates American Society of Anesthesiologists; SD, standard deviation.The choice of the most appropriate summary statistic depends on the type and distribution of data. The following data types are distinguished:2 Nominal data have 2 (eg, sex) or more (eg, blood type) nonordered categories. Ordinal data have categories with a logical order (eg, American Society of Anesthesiologists [ASA] physical status score). Interval data are numeric and have an arbitrary zero point (eg, temperature in Celsius), while ratio data have an absolute zero point (eg, weight). Nominal and ordinal data are correctly summarized with the counts (absolute frequencies) and proportions or percentages (relative frequencies) of observations within the categories. When reporting relative frequencies, the numerator and denominator should both be presented. Interval and ratio data can also be summarized by frequencies within specific strata of the quantitative data (eg, number of patients with age 0–10 years, 11–20 years, etc). These frequencies are commonly reported as a histogram, providing a useful visual display of the data distribution. Two key characteristics of an interval or ratio dataset are (a) its central tendency characteristic—the “average” location of the data and (b) its variability—the extent to which individual values vary around the center. Both should be reported. For approximately normally distributed data, the arithmetic mean appropriately describes the center of the data.3 It is the sum of all observed values, divided by the number of observations. The mean is commonly accompanied by the standard deviation (SD), which describes how far the data points are dispersed around the mean. For normally distributed data, 68% are within 1 SD, 95% are within 2 SDs, and >99% are within 3 SDs on both sides of the mean.3 The median is the value that divides a dataset into 2 equal-sized parts, with the same number of datapoints above and below it.3 It is relatively robust to asymmetric (skewed) distributions, and extreme values (outliers). Therefore, the median is preferred to the mean for non-normally distributed data, and it can also be used for ordinal data.3 The median is commonly reported with the first and third quartiles (Q1, Q3), often loosely referred to as interquartile range. Quartiles divide the dataset into4 equally sized parts, and the interval between Q1 and Q3 contains the middle 50% of the data points. Descriptive statistics are also sometimes used as point estimates of population parameters (eg, using a sample to estimate a proportion or a mean in the population). In this case, they should be accompanied by a confidence interval as a measure of the estimate precision.4

Study of the thermal expansion coefficient of metals using the structural units method

The technique for calculating the thermal expansion coefficient using the structural units method are proposed, allowing to calculate and investigate the dependence of the volume compression and thermal expansion coefficients near the absolute zero point depending on structural units properties and substance thermodynamic parameters. The article presents calculations for some metals. The results can be used in various substance studies near the temperature of absolute zero

High-precision angle sensor based on a Köster’s prism with absolute zero-point

In this publication, a novel approach will be presented to use a compact white-light interferometer based on a Köster’s prism for angle measurements. Experiments show that the resolution of this angle interferometer is in the range of a commercial digital autocollimator, with a focal length of f = 300 mm, but with clearly reduced signal noise and without overshoot artifacts in the signal caused by digital filters. The angle detection of the reference mirror in the Köster’s interferometer is based on analysing the rotation angle of the fringe pattern, which is projected on a CMOS-matrix. The fringe pattern is generated by two displaced spherical wave fronts coming from one fiber-coupled white-light source and getting divided into a reference and a measurement beam by the Köster’s prism. The displacement correlates with the reference angle mirror in one linear direction and with the angle aberrations of the prism in the other orthogonal direction on the CMOS sensor. We will present the experimental and optical setup, the method and algorithms for the image-to-angle processing as well as the experimental results obtained in calibration and long-term measurements.

Fundamentals of Research Data and Variables: The Devil Is in the Details.

Designing, conducting, analyzing, reporting, and interpreting the findings of a research study require an understanding of the types and characteristics of data and variables. Descriptive statistics are typically used simply to calculate, describe, and summarize the collected research data in a logical, meaningful, and efficient way. Inferential statistics allow researchers to make a valid estimate of the association between an intervention and the treatment effect in a specific population, based upon their randomly collected, representative sample data. Categorical data can be either dichotomous or polytomous. Dichotomous data have only 2 categories, and thus are considered binary. Polytomous data have more than 2 categories. Unlike dichotomous and polytomous data, ordinal data are rank ordered, typically based on a numerical scale that is comprised of a small set of discrete classes or integers. Continuous data are measured on a continuum and can have any numeric value over this continuous range. Continuous data can be meaningfully divided into smaller and smaller or finer and finer increments, depending upon the precision of the measurement instrument. Interval data are a form of continuous data in which equal intervals represent equal differences in the property being measured. Ratio data are another form of continuous data, which have the same properties as interval data, plus a true definition of an absolute zero point, and the ratios of the values on the measurement scale make sense. The normal (Gaussian) distribution ("bell-shaped curve") is of the most common statistical distributions. Many applied inferential statistical tests are predicated on the assumption that the analyzed data follow a normal distribution. The histogram and the Q-Q plot are 2 graphical methods to assess if a set of data have a normal distribution (display "normality"). The Shapiro-Wilk test and the Kolmogorov-Smirnov test are 2 well-known and historically widely applied quantitative methods to assess for data normality. Parametric statistical tests make certain assumptions about the characteristics and/or parameters of the underlying population distribution upon which the test is based, whereas nonparametric tests make fewer or less rigorous assumptions. If the normality test concludes that the study data deviate significantly from a Gaussian distribution, rather than applying a less robust nonparametric test, the problem can potentially be remedied by judiciously and openly: (1) performing a data transformation of all the data values; or (2) eliminating any obvious data outlier(s).

Non-LTE line formation of Fe in late-type stars – IV. Modelling of the solar centre-to-limb variation in 3D

Our ability to model the shapes and strengths of iron lines in the solar spectrum is a critical test of the accuracy of the solar iron abundance, which sets the absolute zero-point of all stellar metallicities. We use an extensive 463-level Fe atom with new photoionisation cross-sections for FeI as well as quantum mechanical calculations of collisional excitation and charge transfer with neutral hydrogen; the latter effectively remove a free parameter that has hampered all previous line formation studies of Fe in non-local thermodynamic equilibrium (NLTE). For the first time, we use realistic 3D NLTE calculations of Fe for a quantitative comparison to solar observations. We confront our theoretical line profiles with observations taken at different viewing angles across the solar disk with the Swedish 1-m Solar Telescope. We find that 3D modelling well reproduces the observed centre-to-limb behaviour of spectral lines overall, but highlight aspects that may require further work, especially cross-sections for inelastic collisions with electrons. Our inferred solar iron abundance is log(eps(Fe))=7.48+-0.04.

Ion Coulomb crystals: from quantum technology to chemistry close to the absolute zero point

Ion Coulomb crystals are ordered structures of atomic or molecular ions stored in ion traps at temperatures close to the absolute zero point. These unusual “crystals” form the basis of extremely accurate clocks, provide an environment for precise studies of chemical reactions and enable advanced implementations of the technology for a quantum computer. In this article, we discuss the techniques for generating atomic and molecular Coulomb crystals and highlight some of their applications.

Monitoring the Coldhead of Magnetic Resonance Imaging Systems by Means of Vibration Analysis

Magnetic resonance imaging (MRI) systems require a cooling close to the absolute zero point. This is necessary to avoid thermal losses due to the extremely high currents in the coils of the electromagnet used to generate the static magnetic field. The cooling is usually achieved using helium based refrigerating machine. The coldhead is an important and critical mechanical component in this system. An inefficient or failed coldhead can lead to severe damages to the MRI system or to the loss of helium. Hence, a continuous and reliable monitoring of this system component is necessary but not always available. To tackle this problem, we propose a monitoring system by means of analyzing the structure-borne noises caused by the mechanical activities of the coldhead. For this purpose, a measurement system based on piezoelectric elements was designed and implemented. Vibrations were measured at various locations at the MRI scanner with and without MR imaging. In all positions, the function of the coldhead could be detected. Hence, the developed system is suitable for monitoring an MRI’s coldhead without directly accessing the MR scanner’s hardware or software. For a future long-term monitoring, the aim is to predict a failure of the MRI’s coldhead based on changes in the vibrations signals.

Bilateral fitting subtracting confocal microscopy.

This paper proposes a bilateral fitting subtracting confocal microscopy (BFSCM) based on the optical arrangement of conventional confocal microscopy (CM). BFSCM first uses the data in both sides of a confocal axial response curve, which are very sensitive to the axial position of the sample, for respective linear fitting to obtain two fitting straight lines, and then obtains a difference confocal line by subtraction of the two fitting lines. Finally, it calculates the zero position of the difference confocal line to precisely capture the focus position of the confocal system, and thereby achieving a high-precision measurement of the 3D structure of the sample. The theoretical analyses and experiments indicate that BFSCM can improve the axial resolution, and has anti-interference capability and focusing ability with bipolar absolute zero point tracking, while it does not change the structure and lateral resolution of CM. BFSCM provides a novel method for the improvement of CM axial resolution.

GaiaData Release 1

Context. Gaia is an ESA cornerstone mission launched on 19 December 2013 aiming to obtain the most complete and precise 3D map of our Galaxy by observing more than one billion sources. This paper is part of a series of documents explaining the data processing and its results for Gaia Data Release 1, focussing on the G band photometry. Aims. This paper describes the calibration model of the Gaia photometric passband for Gaia Data Release 1. Methods. The overall principle of splitting the process into internal and external calibrations is outlined. In the internal calibration, a self-consistent photometric system is generated. Then, the external calibration provides the link to the absolute photometric flux scales. Results. The Gaia photometric calibration pipeline explained here was applied to the first data release with good results. Details are given of the various calibration elements including the mathematical formulation of the models used and of the extraction and preparation of the required input parameters (e.g. colour terms). The external calibration in this first release provides the absolute zero point and photometric transformations from the Gaia G passband to other common photometric systems. Conclusions. This paper describes the photometric calibration implemented for the first Gaia data release and the instrumental effects taken into account. For this first release no aperture losses, radiation damage, and other second-order effects have not yet been implemented in the calibration.

Classical Cepheids, what else?

AbstractWe present new and independent estimates of the distances to the Magellanic Clouds (MCs) using near-infrared (NIR) and optical–NIR period–Wesenheit (PW) relations. The slopes of the PW relations are, within the dispersion, linear over the entire period range and independent of metal content. The absolute zero points were fixed using Galactic Cepheids with distances based on the infrared surface-brightness method. The true distance modulus we found for the Large Magellanic Cloud—(m − M)0 = 18.48 ± 0.01 ± 0.10 mag—and the Small Magellanic Cloud—(m − M)0 = 18.94 ± 0.01 ± 0.10 mag—agree quite well with similar distance determinations based on robust distance indicators. We also briefly discuss the evolutionary and pulsation properties of MC Cepheids.

车载激光系统光束控制反射镜角位移测量装置

To control of a Fast Steering Mirror(FSM) stably and precisely in the circumstances of vehicles and ships,a high precision device for angle displacement measurement was designed to provide the mirror sway angle information as a feedback signal to realize the servo closed loop control.As traditional detectors for the FSM are disadvantageous to high-precision work in the mobile circumstance,a precision grating based on the Moire fringe counting measurement principle was designed by using the Chinese characters Tian' splitting phase method.At the same time,the absolute zero point signal against jamming and temperature changing was designed through computer simulation and its contrast ratio was 0.25.Furthermore,in order to realize the miniature,the signal processing circuit was highly integrated.Experimental results indicate that the resolution of the measurement device is 0.15″and the angle precision is higher than 0.4″.This device satisfies the requirements of angle measurement precision in the mobile condition for the high-energy laser projecting systems.

THE CARNEGIE HUBBLE PROGRAM

We present an overview of and preliminary results from an ongoing comprehensive program that has a goal of determining the Hubble constant to a systematic accuracy of 2%. As part of this program, we are currently obtaining 3.6 micron data using the Infrared Array Camera (IRAC) on Spitzer, and the program is designed to include JWST in the future. We demonstrate that the mid-infrared period-luminosity relation for Cepheids at 3.6 microns is the most accurate means of measuring Cepheid distances to date. At 3.6 microns, it is possible to minimize the known remaining systematic uncertainties in the Cepheid extragalactic distance scale. We discuss the advantages of 3.6 micron observations in minimizing systematic effects in the Cepheid calibration of the Hubble constant including the absolute zero point, extinction corrections, and the effects of metallicity on the colors and magnitudes of Cepheids. We are undertaking three independent tests of the sensitivity of the mid-IR Cepheid Leavitt Law to metallicity, which when combined will allow a robust constraint on the effect. Finally, we are providing a new mid-IR Tully-Fisher relation for spiral galaxies.

GRANULATION SIGNATURES IN THE SPECTRUM OF THE VERY METAL-POOR RED GIANT HD 122563

A very high resolution (R=200,000), high signal-to-noise ratio (S/N=340) blue-green spectrum of the very metal-poor ([Fe/H]=-2.6) red giant star HD122563 has been obtained by us at McDonald Observatory. We measure the asymmetries and core wavelengths of a set of unblended FeI lines covering a wide range of line strength. Line bisectors exhibit the characteristic C-shape signature of surface convection (granulation) and they span from about 100 m/s in the strongest FeI features to 800 m/s in the weakest ones. Core wavelength shifts range from about -100 to -900 m/s, depending on line strength. In general, larger blueshifts are observed in weaker lines, but there is increasing scatter with increasing residual flux. Assuming local thermodynamic equilibrium (LTE), we synthesize the same set of spectral lines using a state-of-the-art three-dimensional hydrodynamic simulation for a stellar atmosphere of fundamental parameters similar to those of HD122563. We find good agreement between model predictions and observations. This allows us to infer an absolute zero-point for the line shifts and radial velocity. Moreover, it indicates that the structure and dynamics of the simulation are realistic, thus providing support to previous claims of large 3D-LTE corrections, based on the hydrodynamic model used here, to elemental abundances and fundamental parameters of very metal-poor red giant stars obtained with standard 1D-LTE spectroscopic analyses.

Intracranial landmarks and other techniques to further improve the precision of stereotaxic tracer injections

This study is meant to combine traditional aspects of tracer microinjections using bone landmarks like bregma and lambda with novel procedures in which specific parts of the brain can serve as reference points. For telencephalic and diencephalic injections, the brain surface, the interhemispheric groove and the straight sinus can be used as absolute zero points for dorso-ventral, medio-lateral and rostro-caudal coordinates, respectively. In case of brainstem targets, the surface of the rhomboid fossa, the posterior spinal artery and the obex could serve as reference points along the above-mentioned coordinates. The application of high-precision stereotaxic measurements based on intracranial landmarks and sophisticated surgical procedures can yield well-targeted, small and well circumscribed injection sites that make possible the mapping of discrete nuclear subdivisions or delicate nuclei in the brain.

An absolutely calibratedTeffscale from the infrared flux method

Various effective temperature scales have been proposed over the years. Despite much work and the high internal precision usually achieved, systematic differences of order 100 K (or more) among various scales are still present. We present an investigation based on the infrared flux method aimed at assessing the source of such discrepancies and pin down their origin. We break the impasse among different scales by using a large set of solar twins, stars which are spectroscopically and photometrically identical to the Sun, to set the absolute zero point of the effective temperature scale to within few degrees. Our newly calibrated, accurate and precise temperature scale applies to dwarfs and subgiants, from super-solar metallicities to the most metal-poor stars currently known. At solar metallicities our results validate spectroscopic effective temperature scales, whereas for [Fe/H] -2.5 our temperatures are roughly 100 K hotter than those determined from model fits to the Balmer lines and 200 K hotter than those obtained from the excitation equilibrium of Fe lines. Empirical bolometric corrections and useful relations linking photometric indices to effective temperatures and angular diameters have been derived. Our results take full advantage of the high accuracy reached in absolute calibration in recent years and are further validated by interferometric angular diameters and space based spectrophotometry over a wide range of effective temperatures and metallicities.

Classical Cepheid Pulsation Models. X. The Period‐Age Relation

We present new period-age (PA) and period-age-color (PAC) relations for fundamental and first-overtone classical Cepheids. Current predictions rely on homogeneous sets of evolutionary and pulsation models covering a broad range of stellar masses and chemical compositions. We found that PA and PAC relations present a mild dependence on metal content. Moreover, the use of different PA and PAC relations for fundamental and first-overtone Cepheids improves the accuracy of age estimates in the short-period (log P < 1) range (old Cepheids), because they present smaller intrinsic dispersions. At the same time, the use of the PAC relations improves the accuracy in the long-period (log P ≥ 1) range (young Cepheids), since they account for the position of individual objects inside the instability strip. We performed a detailed comparison between evolutionary and pulsation ages for a sizable sample of LMC (15) and SMC (12) clusters which host at least two Cepheids. In order to avoid deceptive uncertainties in the photometric absolute zero point, we adopted the homogeneous set of B, V, and I data for clusters and Cepheids collected by OGLE. We also adopted the same reddening scale. The different age estimates agree at the level of 20% for LMC clusters and of 10% for SMC clusters. We also performed the same comparison for two Galactic clusters (NGC 6067, NGC 7790), and the difference in age is smaller than 20%. These findings support the use of PA and PAC relations to supply accurate estimates of individual stellar ages in the Galaxy and in external Galaxies. The main advantage of this approach is its independence from the distance.

The Distance to the Large Magellanic Cloud Cluster Reticulum from theK‐Band Period‐Luminosity‐Metallicity Relation of RR Lyrae Stars

We present new and accurate near-infrared J- and Ks-band data of the Large Magellanic Cloud cluster Reticulum. Data were collected with SOFI at the New Technology Telescope and covered an area of approximately 5' × 5' around the center of the cluster. Current data allowed us to derive accurate mean K-band magnitudes for 21 fundamental (RRab) and 9 first-overtone (RRc) RR Lyrae stars. On the basis of the semiempirical K-band period-luminosity-metallicity (PLZK) relation we have recently derived, we find that the absolute distance to this cluster is 18.52 ± 0.005 (random) ±0.117 (systematic). Note that the current error budget is dominated by systematic uncertainty affecting the absolute zero-point calibration and the metallicity scale.

Determination of accurate stellar radial-velocity measures

Wavelength measurements in stellar spectra cannot readily be interpreted as true stellar motion on the sub-km s 1 accuracy level due to the presence of many other eects, such as gravitational redshift and stellar convection, which also produce line shifts. Following a recommendation by the IAU, the result of an accurate spectroscopic radial-velocity observation should therefore be given as the radial-velocity measure, i.e. the absolute spectral shift as measured by an observer at zero gravitational potential located at the solar-system barycentre. Standard procedures for reducing accurate radial-velocity observations should be reviewed to take into account this recommendation. We describe a procedure to determine accurate barycentric radial-velocity measures of bright stars, based on digital cross-correlation of spectra obtained with the ELODIE spectrometer (Observatoire de Haute-Provence) with a synthetic template of Fei lines. The absolute zero point of the radial- velocity measures is linked to the wavelength scale of the Kurucz (1984) Solar Flux Atlas via ELODIE observations of the Moon. Results are given for the Sun and 42 stars, most of them members of the Hyades and Ursa Major clusters. The median internal standard error is 27 m s 1 . The external error is estimated at around 120 m s 1 , mainly reflecting the uncertainty in the wavelength scale of the Solar Flux Atlas. For the Sun we find a radial-velocity measure of+257 11 m s 1 referring to the full-disk spectrum of the selected Fei lines.

The distance to Supernova 1998aq in NGC 3982

The distance to NGC 3982, host galaxy to the Type Ia supernova SN 1998aq, is derived using 32 Cepheids discovered in archival multi-epoch Hubble Space Telescope observations. Employing recent Large Magellanic Cloud Cepheid period–luminosity relations and absolute zero-point, we find a distance to NGC 3982 of , including both random (r) and systematic (s) uncertainties, and ignoring any metallicity dependence in the Cepheid period–luminosity relation. Still unpublished light curve photometry promises to make SN 1998aq one of the most important calibrators for the Type Ia supernova decline rate–peak luminosity relationship.