Absolute Mode Research Articles

A New Kind of Real‐Time PPP Method for GPS Single‐Frequency Receiver Using CORS Network

AbstractRapid and precise positioning using cheaper single‐frequency receivers in wide areas has become one of the research hot spots in present satellite geodesy field. The author proposes a new real‐time modeling method based on regional CORS network. A new precise point positioning service for single‐frequency receiver is also designed and realized. Through serial analysis of practical examples from the CORS networks of Shanxi Province, Hubei Province and Wuhan in China, this paper testifies the feasibility of providing real‐time positioning service for single‐frequency users based on the above methods developed. Results verify that, for reference network with station separation of less than 71 km, user's SD L1 ambiguity can be fixed within several seconds. Once the ambiguity is fixed, single‐frequency user could gain rapid and cm‐level positioning service in absolute positioning mode. Our work provides a new way of rapid and precise point positioning using single‐frequency receivers.

Targeting Proteases in Cardiovascular Diseases by Mass Spectrometry-Based Proteomics

Proteases hydrolyze peptide bonds, thereby controlling the function of proteins and peptides on the posttranslational level. In the cardiovascular system, proteases play pivotal roles in the regulation of blood pressure, coagulation and other essential physiological processes. Accordingly, proteases are prime targets for therapeutic interventions and diagnostics. Proteases are part of complex proteolytic networks comprised of enzymes, inhibitors, activators, substrates and cleavage products. Analyzing these networks on a system-wide level is essential to understanding cardiovascular function and how dysregulation can lead to pathological conditions. Mass spectrometry-based quantitative and dynamic proteomics approaches are leading the way to enhance our knowledge of proteolytic networks such as the renin-angiotensin-system. Here, we critically review proteomics tools utilized in protease biology and provide an overview on how these methods can be used to characterize and validate protease function.

A study on the pressure gradient effect due to a leak in a pressure calibration system

Leaks in a pressure calibration system should be as small as possible in order to reduce the pressure difference between the pressure standard and the device under test (DUT). However, a pressure calibration system that is perfectly sealed from the external environment does not exist, and a pressure difference due to leakage can affect the calibration results. This type of effect should be evaluated precisely because DUTs, such as precise digital pressure gauges with resolutions of less than 1 part in 106, are used widely in industry and the pressure difference due to the leak effect is expected to be larger than the resolution of the DUTs. In addition, precise digital pressure gauges for intercomparisons have been used as transfer standards to determine the degree of equivalence of pressure measurement standards among national measurement institutes (NMIs). This paper explores the leak effect using a leak control valve when a precise digital pressure gauge is calibrated using a pressure balance up to 100 kPa in an absolute mode. Experiments were performed according to an applied pressure, leak amount, tube length and pressure media. It is concluded that the uncertainty caused by a possible leak should be included in the uncertainty evaluation of the calibration results.

Age-corrected reference values for the Heidelberg multi-color anomaloscope

To determine reference values for the HMC anomaloscope (Heidelberg multi-color anomaloscope) of healthy subjects. One hundred and thirteen healthy subjects were divided into four age groups: <20 years of age (ten female, five male), 20-39 years of age (23 female, 15 male), 40-59 years of age (23 female, ten male) and >60 years of age (nine female, 18 male). Match midpoint, matching range (MR) and anomaly quotient (AQ), according to the Moreland equation [blue (436 nm) + blue-green (490 nm) = cyan (480 nm) + yellow (589 nm)] and according to the Rayleigh equation [green (546 nm) + red (671 nm) = yellow (589 nm)] were determined. The neutral adaptation was done showing white light every 5 seconds in absolute mode and every 15 seconds in relative mode. The mean match midpoint according to the Rayleigh equation was 43.9 ± 2.6 scale units in absolute mode. It was highest between 20-39 years (45.2 ± 2.2) and lowest in subjects >60 years of age (42.2 ± 2.2). The mean MR in absolute mode was 3.1 ± 3.5 scale units with a maximum >60 years (4.4 ± 4.4). The MR in relative mode was between 1.6 ± 1.9 (20-39 years) and 4.4 ± 3.8 (>60 years). The resulting mean AQ was 1.01 ± 0.15 in both modes. The mean match midpoint of the Moreland equation was 51.0 ± 5.2 scale units in absolute mode. It was highest between 20-39 years (52.5 ± 5.7), and lowest in subjects >60 years of age (48.7 ± 3.6). The mean MR according to the Moreland equation was lower in absolute mode (13.4 ± 15.6) than in relative mode (16.2 ± 15.2). The mean resulting AQ was 1.02 ± 0.21 in both modes. The values of this study can be used as references for the diagnosis of red-green and blue perception impairment with the HMC anomaloscope.

An initial investigation of the damped resonant behaviour of gas-operated pressure balances

The aim of this investigation into the damped resonant behaviour of the piston of gas-operated pressure balances is to provide insights into ways of improving the short-term performance of gas-operated pressure balances. Initial measurement results are reported for the damped resonant behaviour of two different pressure balances as a function of system volume. The pressure balances are operated using air in absolute mode at 100kPa and the system volume is varied from about 10mL to 250mL. Values for the period, the logarithmic decrement λ and the Q of the oscillation are obtained by fitting the measured damped oscillatory motion of the piston height to a classical damped oscillator model. Results show that the damping is dominated by non-adiabatic pressure variations in the system volume and not by viscous damping of the vertical motion of the piston in the cylinder. The settling time for the oscillations to damp out is primarily determined by the period of oscillation with a lesser influence from variations in λ. Implications for improving pressure balance performance are discussed.

Development of low-pressure calibration system using a pressure balance

A new calibration system for low-pressure is now under development at NMIJ/AIST. The new system is designed to calibrate pressure transducers in the pressure range of less than 10kPa in absolute mode. The pressure generation technique needs only a single pressure balance and the pressure in the bell-jar is used as a calibration pressure instead of the system pressure. In this paper, the outline of the calibration system and the measurement results are described.

FEA calculation of pressure distortion coefficients of gas-operated pressure balances – EURAMET project 1039

Finite element analysis methods were developed and applied to gas piston–cylinder units (PCUs) of piston- and cylinder-floating configuration (2, 5, 10 and 20)cm2 nominal effective area, operated in gauge and absolute mode at pressures (0.06–7.5)MPa to determine their zero pressure and pressure-dependent effective areas, as well as pressure distortion coefficients (λ) with associated uncertainties. Real dimensional properties of the PCUs were used. λ were found to be independent of gas (ideal, N2, He) within the viscous flow model, but strongly dependent on the gap shape, operation mode and elastic properties. Results demonstrate good agreement for λ, with its uncertainty for different PCUs varying between (0.03 and 0.21)×10−6MPa−1 corresponding to maximum relative uncertainties in pressure of (0.07–0.34)×10−6.

High-accuracy Fabry–Perot displacement interferometry using fiber lasers

We describe ongoing work in a Fabry–Perot interferometry system designed to measure displacements over a range of 50 mm with sub-pm uncertainty. The apparatus involves probing two nearby modes of the Fabry–Perot cavity with narrow-linewidth fiber telecom lasers and measuring both the mode spacing and the absolute mode frequencies relative to a third, frequency-stabilized, fiber laser. We explore the improvement in resolution obtained as the frequency separation between the two modes is increased and employ an internal consistency requirement to infer the magnitude of residual systematic errors. The measurement uncertainty is sufficiently small that we are easily able to see the Gouy phase shift as the cavity length is changed over several millimeters.

The heterogeneous photo-oxidation of difenoconazole in the atmosphere

A photo-chemical reactor coupled to a UV spectrometer was used to investigate the degradation of difenoconazole deposited on a quartz surface by atmospheric oxidants, namely ozone and OH radicals. OH-oxidation experiments were conducted relative to a reference compound, the terbuthylazine . The rate constant of heterogeneous OH-oxidation of difenoconazole was found to be (7.1 ± 0.8) 10 −14 cm 3 molecule −1 s −1 . Meanwhile, ozone oxidation experiments were performed in the absolute mode and were interpreted by both, the Langmuir–Rideal (LR) and the Langmuir-Hinshelwood (LH) models of heterogeneous reactions. In the case of ozonolysis, a comparison between both models shows that, within the range of ozone concentration employed in this study, both models fit the experimental data correctly. The obtained results show that the atmospheric life-time of difenoconazole with respect to both oxidants is in the order of several months, meaning that this pesticide is relatively persistent, and may be transported over long distances. ► Heterogeneous reactivity. ► LH and LR models. ► Atmospheric life-time.

Relationship Between Traditional and Ballistic Squat Exercise With Vertical Jumping and Maximal Sprinting

The purpose of this study was to quantify the magnitude of the relationship between vertical jumping and maximal sprinting at different distances with performance in the traditional and ballistic concentric squat exercise in well-trained sprinters. Twenty-one men performed 2 types of barbell squats (ballistic and traditional) across different loads with the aim of determining the maximal peak and average power outputs and 1 repetition maximum (1RM) values. Moreover, vertical jumping (countermovement jump test [CMJ]) and maximal sprints over 10, 20, 30, 40, 60, and 80 m were also assessed. In respect to 1RM in traditional squat, (a) no significant correlation was found with CMJ performance; (b) positive strong relationships (p < 0.01) were obtained with all the power measures obtained during both ballistic and traditional squat exercises (r = 0.53-0.90); (c) negative significant correlations (r = -0.49 to -0.59, p < 0.05) were found with sprint times in all the sprint distances measured when squat strength was expressed as a relative value; however, in the absolute mode, no significant relationships were observed with 10- and 20-m sprint times. No significant relationship was found between 10-m sprint time and relative or absolute power outputs using either ballistic or traditional squat exercises. Sprint time at 20 m was only related to ballistic and traditional squat performance when power values were expressed in relative terms. Moderate significant correlations (r = -0.39 to -0.56, p < 0.05) were observed between sprint times at 30 and 40 m and the absolute/relative power measures attained in both ballistic and traditional squat exercises. Sprint times at 60 and 80 m were mainly related to ballistic squat power outputs. Although correlations can only give insights into associations and not into cause and effect, from this investigation, it can be seen that traditional squat strength has little in common with CMJ performance and that relative 1RM and power outputs for both squat exercises are statistically correlated to most sprint distances underlying the importance of strength and power to sprinting.

Reproductive System and Molecular Phylogenetic Relationships of Fonio Millets (Digitaria spp., Poaceae) with Some Polyploid Wild Relatives

Fonio millets (Digitaria exilis, D. iburua) are minor but important indigenous cereals in the semiarid areas of West-Africa. Recent interest in breeding strategies for these crops requires a better understanding of their biology and genetics. Amplified Fragment Length Polymorphism (AFLP) markers were employed to assess the phylogenetic relationships among cultivated fonio species and some polyploid wild relatives and examine proposed hypotheses on fonio ancestry. The AFLP analysis was found quite suitable for identifying each species. A very strong genetic affinity (over 92% similarity) was detected between the wild D. longiflora and D. ternata and the cultivated D. exilis and D. iburua, respectively. These data provided additional molecular evidence supporting the previous view of direct domestication of fonio millets from these two wild species. High genetic divergences were expectedly found between fonio species and the other taxonomically distant Digitaria taxa investigated. The results also revealed D. ciliaris and D. sanguinalis as separate species sharing close ancestry. Selfing experiments and subsequent progeny analyses using three isozymes supplemented by AFLPs were further conducted to determine the reproductive system in fonio millets. The results revealed apomixis as absolute mode of reproduction of these crops, except D. exilis in which 2% residual sexuality was detected. Additional data documented on seed set and pollen viability suggested that apomixis in fonio would be of pseudogamous type. The data also revealed fonio crops as highly self-compatible and of allopolyploid origin. This study adds new information about the reproductive system and the evolution of fonio, contributing to the knowledge on their biology, and thus providing useful subsides for future genetic improvement of these valuable crops.

Mechanism of sustained oscillations in a fluid flowing past a circular cylinder obstacle

The mechanism of sustained oscillation in the flow past a circular cylinder is investigated numerically, in which impulsive force is given at a certain point in the flow and subsequent spatiotemporal development of induced disturbance is observed. The impulsive force generates an intense localized disturbance at the point of forcing, which is transmitted immediately up to a region just behind the cylinder, and there it yields an transient and eigen modes of disturbance having a packet form. Extending the conventional notions of convective and absolute modes of instability established on the parallel flow approximation to nonparallel flows, we define "passive" and "active" modes of instability, respectively, and evaluate the growth rate of each mode. It was found that the entire flow field is stable to active mode below the critical Reynolds number for the global instability though some extent of the flow behind the cylinder is unstable to passive mode, while the flow becomes unstable to active mode everywhere simultaneously when the Reynolds number exceeds the critical value. The numerical analysis brought us a conclusion that the oscillation is sustained by superiority of the growth of disturbance due to instability over the decrease due to advection of the packet.

Optimal velocity and density profiles for the onset of absolute instability in jets

The absolute/convective character of the linear instability of axisymmetric jets is investigated for a wide range of parallel velocity and density profiles. An adjoint-based sensitivity analysis is carried out in order to maximize the absolute growth rate of jet profiles with and without density variations. It is demonstrated that jets without counterflow may display absolute instability at density ratios well above the previously assumed threshold ρjet/ρ∞ = 0.72, and even in homogeneous settings. Absolute instability is promoted by a strong velocity gradient in the low-velocity region of the shear layer, as well as by a step-like density variation near the location of maximum shear. A new efficient algorithm for the computation of the absolute instability mode is presented.

Mapeamento da Araucaria angustifolia utilizando receptores GPS

Compararam-se, neste trabalho, os resultados do mapeamento planimétrico das árvores de Araucária (Araucaria angustifolia), utilizando a tecnologia GPS nos modos estático diferencial (posicionamento relativo) e estático absoluto. A área de estudo refere-se ao Campus Universitário de Irati - UNICENTRO, no estado do Paraná, Brasil. O mapeamento apontou a presença de 264 Araucárias, sendo possível o posicionamento relativo de 141 árvores, com a precisão variando de 6 a 84 cm; o posicionamento absoluto, possível em todas as Araucárias, apresentou variação de 5 a 14 m. O posicionamento relativo foi possível em 30% das Araucárias onde a declividade foi &gt; 30% e em 57% dos casos em que a área basal foi &gt; 16 m²/ha. Pode-se concluir que o posicionamento relativo possui precisão suficiente para a localização das Araucárias, enquanto o posicionamento absoluto pode causar confusão devido ao baixo grau de precisão quanto ao posicionamento planimétrico. O resultado do posicionamento relativo foi influenciado pela declividade e área basal, principalmente em condições de elevada declividade e elevada área basal.

Progress in Noise Thermometry at 505 K and 693 K Using Quantized Voltage Noise Ratio Spectra

Technical advances and new results in noise thermometry at temperatures near the tin freezing point and the zinc freezing point using a quantized voltage noise source (QVNS) are reported. The temperatures are derived by comparing the power spectral density of QVNS synthesized noise with that of Johnson noise from a known resistance at both 505 K and 693 K. Reference noise is digitally synthesized so that the average power spectra of the QVNS match those of the thermal noise, resulting in ratios of power spectra close to unity in the low-frequency limit. Three-parameter models are used to account for differences in impedance-related time constants in the spectra. Direct comparison of noise temperatures to the International Temperature Scale of 1990 (ITS-90) is achieved in a comparison furnace with standard platinum resistance thermometers. The observed noise temperatures determined by operating the noise thermometer in both absolute and relative modes, and related statistics together with estimated uncertainties are reported. The relative noise thermometry results are combined with results from other thermodynamic determinations at temperatures near the tin freezing point to calculate a value of T − T90 = +4(18) mK for temperatures near the zinc freezing point. These latest results achieve a lower uncertainty than that of our earlier efforts. The present value of T − T90 is compared to other published determinations from noise thermometry and other methods.

SU-GG-T-266: Impacts of the Sensitomertic Curve Depending on Scanning Parameters and Post-Operative Corrections on Radiochromic Film Dosimetry

Purpose: Impacts of sensitometric curve depending on scanning parameters and post‐operative processes to correct active layer and background effects on radiochromic film dosimetry were investigated to determine the key factors for more accurate dose verification. Method and Materials: Dose discrepancies were evaluated in the 60°‐enhanced dynamic wedged field and intensity‐modulated beams using the GafChromic EBT2 films and the software developed in‐house. Dosimetric effects were analyzed as the following conditions were applied: adjustment of the scanning contrast and brightness, background corrections in relative and absolute mode using non‐irradiated or irradiated film corresponding delivered dose levels, and active layer correction to lessen the thickness difference of the response material. Maximum dose and pass ratio applied the gamma criteria (distance‐to‐agreement of 3 mm and dose difference of 3%) were compared with planning system results in the wedged and the modulated field, respectively. Results: Absolute dose discrepancies of 3–6 %, pass ratio difference of 1–9% were generated by the effect of the applied sensitometric curve. Dose discrepancies were lower than 1% according to the correction methods of background or active layer correction. Slope variations of sensitometric curves led to different dose differences at each dose range. Thus under the same scanning conditions, lower pass ratio was represented in modulated beams, although the discrepancy at the point of maximum dose was decreased in wedged field. When the exposed film was used for background correction, dose differences in the portion of irradiated field were reduced, but the pass ratio was not improved because of the non‐uniform film response according to the dose levels. Conclusion: Determination of the sensitometric curve influenced by the scanning parameters was the primary factor to the dose differences. Under the selection of the sensitometric curve and post‐operative correction methods, dose discrepancy can be minimized for required radiochromic film dosimetry.

The linear regime of the two-plasmon decay instability in inhomogeneous plasmas

A linear fluid code solving the equations for the two-plasmon decay (TPD) instability has been developed and used to study the TPD instability. Both absolute and convective modes are observed in the simulations using this code, which show that the absolute modes are located close to the quarter-critical-density surface while the convective modes are located in the lower-density region. The maximum growth rates of the absolute modes measured in the simulations agree well with the theoretical results in the limits of large and small values of the parameter β∝Te2/(Iλ2), where Te is the electron temperature, I is the laser intensity, and λ is the laser wavelength. The simulation results also agree with the β-dependent threshold for absolute TPD. A derivation of the convective gain that retains the dependence on electron temperature and perpendicular mode number is presented and it is in good agreement with the simulation results.

1–15,000 Pa Absolute mode comparisons between the NIST ultrasonic interferometer manometers and non-rotating force-balanced piston gauges

The National Institute of Standards and Technology (NIST) Low Pressure Manometry Project maintains and operates primary standard ultrasonic interferometer manometers (UIMs) over the pressure range of 1 mPa to 360 kPa. Over the past decade a new type of customer gauge, the non-rotating force-balanced piston gauge or FPG (model 8601, DH Instruments, a Fluke Company 1 Certain commercial equipment, instruments, or materials are identified in this paper to foster understanding. Such identification does not imply endorsement by NIST nor does it imply that the equipment or materials are necessarily the best for the purpose. 1 ) has been introduced to the standards community that covers the range of ≈1–15,000 Pa and is capable of both absolute and differential measurement modes. Since 2002, NIST customers 2 NIST customers shall not be identified. 2 have requested that four different FPG units be compared to the NIST primary pressure ultrasonic interferometer manometer standards (UIMs). The results of the comparisons were that all four FPG units were within manufacturers stated uncertainty (0.008 Pa + 30 × 10 −6 × P for absolute mode) when compared against the NIST UIMs at pressures between 10 Pa and 15,000 Pa (absolute mode). At pressures between 5 Pa and 10 Pa, the results were generally within manufacturer’s specifications. Below 5 Pa some of the FPG units were outside of manufacturer’s uncertainty specifications. The use of an isolating capacitance diaphragm gauge (CDG) was necessary during the comparisons to prevent humidified gas from the FPG from entering the NIST 160 kPa mercury UIM primary pressure standard. The results of these four different comparison tests will be discussed in detail, along with test conditions, equipment set-up, and test uncertainty analysis.

Direct Evidence for Nitrogen Ligation to the High Stability Semiquinone Intermediate in Escherichia coli Nitrate Reductase A

The membrane-bound heterotrimeric nitrate reductase A (NarGHI) catalyzes the oxidation of quinols in the cytoplasmic membrane of Escherichia coli and reduces nitrate to nitrite in the cytoplasm. The enzyme strongly stabilizes a menasemiquinone intermediate at a quinol oxidation site (Q(D)) located in the vicinity of the distal heme b(D). Here molecular details of the interaction between the semiquinone radical and the protein environment have been provided using advanced multifrequency pulsed EPR methods. (14)N and (15)N ESEEM and HYSCORE measurements carried out at X-band ( approximately 9.7 GHz) on the wild-type enzyme or the enzyme uniformly labeled with (15)N nuclei reveal an interaction between the semiquinone and a single nitrogen nucleus. The isotropic hyperfine coupling constant A(iso)((14)N) approximately 0.8 MHz shows that it occurs via an H-bond to one of the quinone carbonyl group. Using (14)N ESEEM and HYSCORE spectroscopies at a lower frequency (S-band, approximately 3.4 GHz), the (14)N nuclear quadrupolar parameters of the interacting nitrogen nucleus (kappa = 0.49, eta = 0.50) were determined and correspond to those of a histidine N(delta), assigned to the heme b(D) ligand His-66 residue. Moreover S-band (15)N ESEEM spectra enabled us to directly measure the anisotropic part of the nitrogen hyperfine interaction (T((15)N) = 0.16 MHz). A distance of approximately 2.2 Abetween the carbonyl oxygen and the nitrogen could then be calculated. Mechanistic implications of these results are discussed in the context of the peculiar properties of the menasemiquinone intermediate stabilized at the Q(D) site of NarGHI.

Absolute and convective instability of cylindrical Couette flow with axial and radial flows

Imposing axial flow in the annulus and/or radial flow through the cylindrical walls in a Taylor–Couette system alters the stability of the flow. Theoretical methods and numerical simulations were used to determine the impact of imposed axial and radial flows, homogeneous in the axial direction, on the first transition of Taylor–Couette flow in the framework of convective and absolute instabilities. At low axial Reynolds numbers the convective instability is axisymmetric, but convective helical modes with an increasing number of helices having a helicity opposite that of the base flow dominate as the axial flow increases. The number of helices and the critical Taylor number are affected only slightly by the radial flow. The flow becomes absolutely unstable at higher Taylor numbers. Absolutely unstable axisymmetric modes occur for inward radial flows, while helical absolute instability modes having a helicity identical to that of the base flow occur at high enough axial Reynolds numbers for outward radial flow.