Science.gov

Sample records for geomagnetic cut-off rigidity

  1. Upper cut-off rigidity for corotation anisotropy during solar activity cycles 20 and 21

    NASA Technical Reports Server (NTRS)

    Ahluwalia, H. S.; Riker, J. F.

    1985-01-01

    At the Eleventh International Conference on Cosmic Rays in 1969, the results of a study of the solar diurnal variations of solar rays observed during the ascending phase of solar activity cycle twenty was discussed. The diurnal variation, observed underground during 1965-68 period, and results from an extraterrestrial anisotropy having a continuously increasing upper cut-off rigidity R sub c were reported. However, the coupling functions applicable to underground telescopes were controversial then. This situation has improved now. Those results wsere re-examined and extended to cover the period 1965-78. The coupling functions given by Murakami et al. for underground muons and those given by Lockwood and Weber for neutron monitors were used showed that a great deal of care should be exercised in the value of R sub c was calculated. Although numerical values of R sub c are a little different, the trend for 1965-68 period remains unchanged. Highest value of R sub c occur in 1970 and the lowest value occurs in 1976.

  2. Atmospheric secondary charged cosmic radiation at a place of 11.5 GV geomagnetic cut-off

    NASA Astrophysics Data System (ADS)

    Azcarate, I. N.

    2002-04-01

    An experiment performed with a balloon-borne plastic scintillator is described. The detector system was transported by a stratospheric balloon, that was launched from Reconquista, province of Santa Fe, Argentina, on 24 February 1992. The geomagnetic cut-off of the site was 11.5 GV. The energy-loss spectra of both the atmospheric gamma radiation ( for E^γ>= 4.15 MeV) and the charged component of the secondary cosmic radiation were alternatively measured at different altitudes, during the ascent of the balloon, and at ceiling altitude. The author analyzed the atmospheric gamma-ray spectrum in a previous paper ( Azcárate, 2000). It was necessary to perform the computation of the response of the detector to the charged radiation in order to explain , at least qualitatively, the energy-loss spectrum in the detector produced by this type of radiation. It is argued that at ceiling altitude the observed feature in the spectrum is produced mainly by relativistic muons falling horizontally upon the detector. The growth curve for the counting rate below this feature and the intensity of relativistic μ-mesons were also obtained. References : Azcárate, I.N., Revista Mexicana de Astronomía y Astrofísica, 36, 81, 2000.

  3. Geomagnetic Cutoff Rigidity Computer Program: Theory, Software Description and Example

    NASA Technical Reports Server (NTRS)

    Smart, D. F.; Shea, M. A.

    2001-01-01

    The access of charged particles to the earth from space through the geomagnetic field has been of interest since the discovery of the cosmic radiation. The early cosmic ray measurements found that cosmic ray intensity was ordered by the magnetic latitude and the concept of cutoff rigidity was developed. The pioneering work of Stoermer resulted in the theory of particle motion in the geomagnetic field, but the fundamental mathematical equations developed have 'no solution in closed form'. This difficulty has forced researchers to use the 'brute force' technique of numerical integration of individual trajectories to ascertain the behavior of trajectory families or groups. This requires that many of the trajectories must be traced in order to determine what energy (or rigidity) a charged particle must have to penetrate the magnetic field and arrive at a specified position. It turned out the cutoff rigidity was not a simple quantity but had many unanticipated complexities that required many hundreds if not thousands of individual trajectory calculations to solve. The accurate calculation of particle trajectories in the earth's magnetic field is a fundamental problem that limited the efficient utilization of cosmic ray measurements during the early years of cosmic ray research. As the power of computers has improved over the decades, the numerical integration procedure has grown more tractable, and magnetic field models of increasing accuracy and complexity have been utilized. This report is documentation of a general FORTRAN computer program to trace the trajectory of a charged particle of a specified rigidity from a specified position and direction through a model of the geomagnetic field.

  4. Supplemental Summary of Cutoff Rigidities Calculated Using the International Geomagnetic Reference Field for Various Epochs.

    DTIC Science & Technology

    1982-11-01

    Rigidities Calculated Using the International -Geomagnetic Reference Field for Various Epochs M.A. SHEA D.F. SMART 1 NOVEMBER 1982 Approved for publie...SUMMARY OF CUTOFF Scientific. Interim. RIGIDITIES CALCULATED USING THE INTER -_ _________ NATIONAL GEOMAGNETIC REFERENCE FIELD 6 PERFORMING 01G. REPORT...n-b.’I Cosmic rays Cutoff rigidities Geomagnetic field 20 ABSTRACT (ContinuC0 e o, sid. it ---. 0, -,d id- 5,.- 550,5- Tables of cosmic-ray cutoff

  5. The Development of a Dynamic Geomagnetic Cutoff Rigidity Model for the International Space Station

    NASA Technical Reports Server (NTRS)

    Smart, D. F.; Shea, M. A.

    1999-01-01

    We have developed a computer model of geomagnetic vertical cutoffs applicable to the orbit of the International Space Station. This model accounts for the change in geomagnetic cutoff rigidity as a function of geomagnetic activity level. This model was delivered to NASA Johnson Space Center in July 1999 and tested on the Space Radiation Analysis Group DEC-Alpha computer system to ensure that it will properly interface with other software currently used at NASA JSC. The software was designed for ease of being upgraded as other improved models of geomagnetic cutoff as a function of magnetic activity are developed.

  6. 49 CFR 229.93 - Safety cut-off device.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 4 2011-10-01 2011-10-01 false Safety cut-off device. 229.93 Section 229.93 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION... Equipment § 229.93 Safety cut-off device. The fuel line shall have a safety cut-off device that— (a)...

  7. 49 CFR 229.93 - Safety cut-off device.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Safety cut-off device. 229.93 Section 229.93 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION... Equipment § 229.93 Safety cut-off device. The fuel line shall have a safety cut-off device that— (a)...

  8. Magnetospheric effects of cosmic rays. 1. Long-term changes in the geomagnetic cutoff rigidities for the stations of the global network of neutron monitors

    NASA Astrophysics Data System (ADS)

    Gvozdevskii, B. B.; Abunin, A. A.; Kobelev, P. G.; Gushchina, R. T.; Belov, A. V.; Eroshenko, E. A.; Yanke, V. G.

    2016-07-01

    Vertical geomagnetic cutoff rigidities are obtained for the stations of the global network of neutron monitors via trajectory calculations for each year of the period from 1950 to 2020. Geomagnetic cutoff rigidities are found from the model of the Earth's main field International Geomagnetic Reference Field (IGRF) for 1950-2015, and the forecast until 2020 is provided. In addition, the geomagnetic cutoff rigidities for the same period are obtained by Tsyganenko model T89 (Tsyganenko, 1989) with the average annual values of the Kp-index. In each case, the penumbra is taken into account in the approximation of the flat and power spectra of variations of cosmic rays. The calculation results show an overall decrease in geomagnetic cutoff rigidities, which is associated with the overall decrease and restructuring of the geomagnetic field during the reporting period, at almost all points.

  9. Rigidity Dependence of Cosmic Ray Modulation

    NASA Astrophysics Data System (ADS)

    Agarwal Mishra, Rekha; Mishra, Rajesh Kumar

    2012-07-01

    The various observed harmonics of the cosmic ray variation may be understood on a unified basis if the free space cosmic ray anisotropy is non-sinusoidal in form. The major objective of this paper is to study the first three harmonics of cosmic ray intensity on geo-magnetically quiet days over the period 1965-1990 for Deep River, Goose Bay and Tokyo neutron monitoring stations. The amplitude of first harmonic remains high for Deep River having low cutoff rigidity as compared to Tokyo neutron monitor having high cutoff rigidity on quiet days. The diurnal amplitude significantly decreases in 1987 at Deep River and in 1986 at Tokyo during solar activity minimum years. The diurnal time of maximum significantly shifts to an earlier time as compared to the corotational direction at both the stations having different cutoff rigidities. The time of maximum for first harmonic significantly shifts towards later hours and for second harmonic it shifts towards earlier hours at low cutoff rigidity station i.e. Deep River as compared to the high cut off rigidity station i.e. Tokyo on quiet days. The amplitude of second/third harmonics shows a good positive correlation with solar wind velocity, while the others (i.e. amplitude and phase) have no significant correlation on quiet days. The solar wind velocity significantly remains in the range 350 to 425 km/s i.e. being nearly average on quiet days. The amplitude and direction of the anisotropy on quiet days are weakly dependent on high-speed solar wind streams for these neutron monitoring stations of low and high cutoff rigidity threshold. Keywords: cosmic ray, cut off rigidity, quiet days, harmonics.

  10. Environmental sampling: Issues for the cut-off regime

    SciTech Connect

    Fearey, B.L.

    1995-09-01

    The fissile material cut-off treaty (FMCT) initiative under the Conference on Disarmament mandate is envisioned to include certain aspects of environmental sampling and monitoring. One of the intents of this treaty is to bring certain non-NPT signatories (e.g., threshold states) under this treaty agreement along with the nuclear weapon states (NWSs). This paper provides a brief overview of some of the relevant issues that may be involved in the implementation and use of environmental monitoring for (1) verification of the cut-off regime declarations, (2) the detection of undeclared activities, and, (3) application in non-routine inspections. The intent is to provide backstopping information important for treaty negotiators. Specific issues addressed within this paper include signature sampling, differences in the proposed detection regime, potential signature integrators, specific examples and spoofing concerns. Many of these issues must be carefully considered and weighed in order to create a credibly verifiable inspection regime. Importantly, the cut-off treaty must enable nondiscriminatory implementation, while carefully assuring that nonproliferation treaty requirements are maintained (i.e., preventing unintentional release of critical weapons design information--potentially through environmental sampling and analysis).

  11. 76 FR 33161 - Installation and Use of Engine Cut-off Switches on Recreational Vessels

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-06-08

    ... SECURITY Coast Guard 33 CFR Parts 175 and 183 RIN 1625-AB34 Installation and Use of Engine Cut-off Switches... on whether it should require engine cut-off switches as a standard safety feature on propulsion... whether it should require operators of these recreational vessels to use engine cut-off switches....

  12. Energetics of southeastern Pacific cut-off lows

    NASA Astrophysics Data System (ADS)

    Gan, Manoel Alonso; Piva, Everson Dal

    2016-06-01

    The existence of cut-off lows (COLs) over South Pacific and South America is often associated with adverse weather events such as intense precipitation over the central region of South America, frost episodes in southern Brazil and the development of Andes lee cyclones and intense cyclones over the southern coast of Brazil. Despite this importance, the formation and maintenance mechanisms of the COLs are not well understood. To detail the significant variability in terms of the eddy kinetic energy equation for fifty cases of COLs that formed over the southeastern Pacific Ocean is the aim of this study. Only the cases of COLs that formed over the ocean and remained there during most of their life were chosen. The main terms of the equation [ageostrophic flux convergence (AFC), baroclinic conversion (BRC) and barotropic conversion (BRT)] were calculated using the 6-hourly gridded data from the National Centers for Environmental Prediction/Department of Energy reanalysis. The formation mechanism of the COLs was associated with BRC and AFC. During the midlife period, the BRC term converted eddy kinetic energy to eddy potential energy and the AFC had a positive contribution until 6 h after the midlife point. In the dissipation phase, the BRC term remained positive and AFC became negative. The BRT extracted kinetic energy from the COL during the entire life cycle. The AFC term was the most important in all phases of the cut-off lifetime, and it was the responsible for extending the cut-off lifetime while the others terms were negatives.

  13. Permeability porosity relationships (K, Phi cut-off)

    SciTech Connect

    Djettou, F.; Reda, H.

    1995-08-01

    Several reservoirs of Lower Devonian in Ghadames basin present porosities greater than 10 Pu, but during the test they are rather impermeable. It seems that this phenomena extends to BERKINE and Rhourd Messaoud areas. This seriously affect the estimation of recovery reserves. The best we can do is to study and try to understand reservoir problems. The method we choose is based on statistical analysis of test results and their comparison with core and log measurements. It concerns mainly cummulative curves of productive and non-productive tests (dry test). This involves about 20 wells where are can define: Siegenian with: Fine grained in BBK and ROM Coarse grained toward BRN - Emsian is rather homogeneous in the region. The sand cut-off porosity is greater than 11 Pu. However the reservoir can`t produce itself then we can not take account in reserve estimation. In conclusion, a sandy reservoir of Lower Devonian in Ghadames basin may be very porous (11-12%) and impermeable while in the other cases reservoirs can produce with porosity of 7 or 8 Po. However a HC definition based on cut-off porosity in Ghadames basin should be done before net pay an recovery reserves estimation.

  14. Polypharmacy Cut-Off for Gait and Cognitive Impairments

    PubMed Central

    Pothier, Kristell; Morello, Remy; Lelong-Boulouard, Véronique; Lescure, Pascale; Bocca, Marie-Laure; Marcelli, Christian; Descatoire, Pablo; Chavoix, Chantal

    2016-01-01

    Background: Polypharmacy is a well-established risk factor for falls, and these are one of the major health problems that affect the quality of life as people age. However, the risk of mobility and cognitive impairments consecutive to polypharmacy has been little addressed, despite the association between these adverse outcomes and falls. Moreover, the rare polypharmacy cut-offs were all but one arbitrarily determined. Objective: Studying relationships between polypharmacy and both mobility and cognitive impairments, and statistically determining a cut-off point in the number of medicinal molecule beyond which polypharmacy has deleterious consequences with respect to mobility and cognitive impairment. Methods: We enrolled 113 community-dwelling adults aged 55 years and older with a fall history, with or without injury, in the previous year. We carefully collected information about daily medicinal molecules taken. We assessed basic mobility and global cognition with the Time-Up-and-Go and the Montreal Cognitive Assessment (MoCA) test, respectively (clinicaltrials.gov NCT02292316). Results: Timed-Up and Go test and MoCA scores were both significantly correlated with the number of molecule, used. Receiver Operating Characteristic curves indicate, with high prediction (p < 0.002), that daily consumption of five or more molecules is associated with risk for both impaired mobility and global cognition. These relationships were independent of the number of comorbidities and of the pharmacological class. Conclusion: Community-dwelling adults aged 55 years and older who take five or more daily medicinal molecules are at high risk for both mobility and cognitive impairments. Physicians and patients should be aware of these new findings, especially when there are multiple prescribers involved in the care of the patient. PMID:27630572

  15. Effect of cut-off points on performance of laser fluorescence for detecting occlusal caries.

    PubMed

    Braga, Mariana M; Mendes, Fausto M; Imparato, José Carlos P; Rodrigues, Célia R M D

    2007-01-01

    This in vitro study aimed to evaluate the influence of cut-off points on the performance of laser fluorescence (LF) in detecting occlusal caries in permanent and primary teeth. The use of different cut-off points influenced the performance of LF device in detection of occlusal caries in both kind of teeth, but the performance in permanent teeth suffered more influence from variation of cut-off points scales than in primary group.

  16. Geomagnetic and atmospheric effects

    NASA Astrophysics Data System (ADS)

    Stoker, P. H.

    1983-08-01

    Geomagnetic and atmospheric processes affecting cosmic-ray earthbound spectrometry are analyzed. The topics discussed include: cutoff rigidities and asymptotic directions; cosmic ray secondaries in the atmosphere and magnetosphere; neutron counters without lead and neutron monitors; and coupling coefficients/yield functions and response functions of cosmic ray detectors. Theoretical simulations of the atmosphere and geomagnetism are presented, taking into account such factors as geomagnetic ring currents and meteorological effects. Diagrams and cutoff rigidity contours are included.

  17. Diagnostics principle of microwave cut-off probe for measuring absolute electron density

    SciTech Connect

    Jun, Hyun-Su

    2014-08-15

    A generalized diagnostics principle of microwave cut-off probe is presented with a full analytical solution. In previous studies on the microwave cut-off measurement of weakly ionized plasmas, the cut-off frequency ω{sub c} of a given electron density is assumed to be equal to the plasma frequency ω{sub p} and is predicted using electromagnetic simulation or electric circuit model analysis. However, for specific plasma conditions such as highly collisional plasma and a very narrow probe tip gap, it has been found that ω{sub c} and ω{sub p} are not equal. To resolve this problem, a generalized diagnostics principle is proposed by analytically solving the microwave cut-off condition Re[ε{sub r,eff}(ω = ω{sub c})] = 0. In addition, characteristics of the microwave cut-off condition are theoretically tested for correct measurement of the absolute electron density.

  18. Surface Tension of Methanol as a Function of cut-off Radius and Temperature Controllers

    NASA Astrophysics Data System (ADS)

    Obeidat, Abdalla; Jaradat, Adnan; Hamdan, Bushra

    Molecular dynamics is used to calculate the surface tension of van Leeuwen methanol. The van Leeuwen model of methanol is chosen over other models of methanol, since this model is widely used to study nucleation at low temperature. Usually, scientists use the cut-off radius to be three order of magnitude of segment diameter. In this study, we varied the cut-off radius to estimate the best cut-off at which the surface tension reaches its plateau. After deciding the best cut-off radius for van der Waals and Coulomb interactions (CUT-OFF and PME were used for Coulomb interaction), we varied the temperature controller (van-Housen, Berendsen, and v-rescale) to decide the best temperature controller to be used to study methanol. In all simulations, Gromacs is used at T =200-300K with periodic boundary conditions in all dimensions. JUST.

  19. Symptom-dependent cut-offs of urine metanephrines improve diagnostic accuracy for detecting pheochromocytomas in two separate cohorts, compared to symptom-independent cut-offs.

    PubMed

    Cho, Yoon Young; Song, Kee-Ho; Kim, Young Nam; Ahn, Seong Hee; Kim, Hyeonmok; Park, Sooyoun; Suh, Sunghwan; Kim, Beom-Jun; Lee, Soo-Youn; Chun, Sail; Koh, Jung-Min; Lee, Seung Hun; Kim, Jae Hyeon

    2016-10-01

    The development of advanced imaging techniques has increased the detection of subclinical pheochromocytomas. Because of the substantial proportions of subclinical pheochromocytomas, measurement of urine metanephrine concentrations is crucial due to detect or exclude pheochromocytoma. Although urine metanephrines are elevated in symptomatic subjects, diagnostic cut-offs according to the presence of adrenergic symptoms have not been studied. Pheochromocytomas patients who underwent adrenalectomy at Samsung Medical Center and a control group were compared to determine cut-off concentrations of urine metanephrines. An independent population was analyzed for urine metanephrines with different kits to validate the improvement in diagnostic accuracy using adjusted cut-offs. Symptom-dependent cut-offs of urine metanephrines were higher for symptomatic patients (307 μg/day in males, 235 μg/day in females for urine metanephrine, and 1,045 μg/day in males and 457 μg/day in females for urine normetanephrine) than for asymptomatic patients (206 μg/day in males, 199 μg/day in females for urine metanephrine, and 489 μg/day in males and 442 μg/day in females for urine normetanephrine). Symptom-dependent cut-offs of urine metanephrines improved a specificity from 92.7 % to 96.3 % and a high sensitivity of 97.8 % was maintained. Using the Symptom-dependent cut-offs raised diagnostic accuracy by 5.5 % (p <0.001). Similar trend was also observed in an independent population using different hormone kits. Using symptom-dependent cut-offs of urine metanephrines in symptomatic patients for pheochromocytomas resulted in a significant improvement in diagnostic accuracy in two separate cohorts.

  20. Cut-off fuel exhaust mechanism in fuel injection pump

    SciTech Connect

    Ikeuchi, H.

    1988-08-23

    This patent describes a fuel injection pump having an exhaust means for exhausting fuel from the fuel pump at the time of cut-off of fuel flow through the pump, comprising: a pump body for positioning in a pump space for containing fuel to be pumped, the pump body having a fuel passage extending thereinto from the pump space and a valve means in the fuel passage; a plunger barrel mounted in the pump body and having a plunger bore therein and a fuel intake port extending through the plunger barrel from a position opposite the inner end of the fuel passage into the plunger bore; a plunger rotatably and slidably mounted in the plunger bore and defining a pressurizing chamber at the inner end of the plunger bore; the plunger barrel having an oil passage extending from the end within which the pressurizing chamber is defined to the periphery of the plunger barrel; the pump body having a lead hole therethrough from a position opposite the end of the oil passage at the periphery of the plunger barrel to the outside of the pump body, and further having an oil chamber extending thereinto from a position on the pump body near the end of the oil passage and an exhaust passage extending from the inner part of the oil chamber to the outside of the pump body and opening into the pump space; a valve housing mounted on the pump body over the end of the lead hole and the opening into the oil chamber and having a valve guide hole therein opening into the oil chamber and having a valve seat around the end thereof and having an oil induction hole therethrough from a position opposite the end of the lead hole and into the valve guide hole.

  1. Optimal cut-off values and population means of waist circumference in different populations.

    PubMed

    Wang, Zhiqiang; Ma, Jun; Si, Damin

    2010-12-01

    Abdominal obesity is a risk factor for cardiometabolic disease, and has become a major public health problem in the world. Waist circumference is generally used as a simple surrogate marker to define abdominal obesity for population screening. An increasing number of publications solely rely on the method that maximises sensitivity and specificity to define 'optimal' cut-off values. It is well documented that the optimal cut-off values of waist circumference vary across different ethnicities. However, it is not clear if the variation in cut-off values is a true biological phenomenon or an artifact of the method for identifying optimal cut-off points. The objective of the present review was to assess the relationship between optimal cut-offs and population waist circumference levels. Among sixty-one research papers, optimal cut-off values ranged from 65·5 to 101·2 cm for women and 72·5 to 103·0 cm for men. Reported optimal cut-off values were highly correlated with population means (correlation coefficient: 0·91 for men and 0·93 for women). Such a strong association was independent of waist circumference measurement techniques or the health outcomes (dyslipidaemia, hypertension or hyperglycaemia), and existed in some homogeneous populations such as the Chinese and Japanese. Our findings raised some concerns about applying the sensitivity and specificity approach to determine cut-off values. Further research is needed to understand whether the differences among populations in waist circumference were genetically or environmentally determined, and to understand whether using region-specific cut-off points can identify individuals with the same absolute risk levels of metabolic and cardiovascular outcomes among different populations.

  2. Upper and lower bounds for the speed of pulled fronts with a cut-off

    NASA Astrophysics Data System (ADS)

    Benguria, R. D.; Depassier, M. C.; Loss, M.

    2008-02-01

    We establish rigorous upper and lower bounds for the speed of pulled fronts with a cut-off. For all reaction terms of KPP type a simple analytic upper bound is given. The lower bounds however depend on details of the reaction term. For a small cut-off parameter the two leading order terms in the asymptotic expansion of the upper and lower bounds coincide and correspond to the Brunet-Derrida formula. For large cut-off parameters the bounds do not coincide and permit a simple estimation of the speed of the front.

  3. Integrated optical isolator based on nonreciprocal-mode cut-off.

    PubMed

    Hemme, H; Dötsch, H; Hertel, P

    1990-06-20

    A concept of an integrated optical isolator is presented which uses the TM(0) mode propagating perpendicular to the in-plane magnetization of a planar magnetooptical waveguide. The cut-off thickness of the waveguide depends on the propagation direction. If the magnetic film has a strong Faraday rotation and is weakly guiding, the cut-off thicknesses for forward and backward propagation differ markedly. Operating close to cut-off yields a large difference between coupling efficiencies to the waveguide for forward and backward propagation.

  4. Flow Characteristics with Variations of Cut-Off Angle of Multi-Blade Fan for Ventilation

    NASA Astrophysics Data System (ADS)

    Kang, Kyung Jun; Park, Jun Geon; Shin, You Hwan; Kim, Kwang Ho

    2010-06-01

    This study investigated on details of flow characteristics of a multi-blade fan for domestic ventilation. Experiments and analysis were carried out to describe on flow pattern with variations of cut-off angle near the scroll-housing throat, which were performed by PIV measurement for the flow field and by total pressure probes. The stagnation point at cut-off region of the fan moves to the exit of the scroll housing as cut-off angle increases. The movement of stagnation point and the variation of throat area of the scroll housing influence to the distribution of velocity magnitude at the exit of the fan. Furthermore, a large distortion of the velocity distribution at the scroll exit causes to increase mixing loss along the flow path. The improvement of the fan design on cut-off is expected through understanding the flow pattern.

  5. Variation of the first cut-off frequency of the Earth-ionosphere waveguide observed by DEMETER

    NASA Astrophysics Data System (ADS)

    Toledo-Redondo, S.; Parrot, M.; Salinas, A.

    2012-04-01

    More than four years of VLF electric field data recorded by DEMETER have been analyzed, in order to monitor the first cut-off frequency (QTM1) of the Earth-ionosphere waveguide, at around 1.6-1.8 kHz. Since losses in a waveguide are maximized right at the cut-off frequency, DEMETER (˜700 km orbit) can detect the minimum of energy of the leaking fields coming from the waveguide. This measurement permits to draw a global map of its value (f1), which is directly related to the effective height of the ionosphere (h) by the relation f1 = c/2h (c is the speed of light). It enables the remote sensing of the D region, which is one of the less known layers of the ionosphere, because it is too low for satellites to orbit inside it and too high for balloons to reach it. The effective height depends mainly on the electron density (Ne) and neutral density (Nn) profiles, which determine the plasma frequency and the electron mobility. The effective height shifts downward 5-10 km in southern warm season in the South Pacific Ocean. Another effect is observed in the Indian and Atlantic Oceans; the effective height decreases its value twice a year, in the area of roughly ±15° from the geomagnetic equator. The main causes for the changes on the effective reflection height are the solar radiation and the thunderstorm activity. However, the observed shifts are more prominent over the oceans, and a possible explanation for this difference could be attributed to i) less polluted conditions above the oceans (aerosols change the atmospheric conductivity and then the global atmospheric electric circuit), ii) the effect of the current associated to the thunderclouds on the bottom of the ionosphere because thunderstorms are much more numerous above land, or iii) ionization by elves because their occurrence is larger above oceans.

  6. Resistive magneto-hydrodynamical cut-off of Alfvén wave in fully ionized plasmas

    SciTech Connect

    Vranjes, J.; Kono, M.

    2014-01-15

    The term cut-off in the theory of the Alfvén wave is used to describe several different phenomena. In this work, the cut-off due to magnetohydrodynamic resistive damping in fully ionized plasmas is revisited. This cut-off requires short enough wavelengths, it is routinely discussed in numerous works, and graphs depicting it are available even in textbooks. We show that this cut-off is hardly ever possible in real plasmas. This is due to the fact that some essential criteria and conditions become strongly violated in order to achieve the cut-off.

  7. The critical wave speed for the Fisher Kolmogorov Petrowskii Piscounov equation with cut-off

    NASA Astrophysics Data System (ADS)

    Dumortier, Freddy; Popovic, Nikola; Kaper, Tasso J.

    2007-04-01

    The Fisher-Kolmogorov-Petrowskii-Piscounov (FKPP) equation with cut-off was introduced in (Brunet and Derrida 1997 Shift in the velocity of a front due to a cut-off Phys. Rev. E 56 2597-604) to model N-particle systems in which concentrations less than ɛ = 1/N are not attainable. It was conjectured that the cut-off function, which sets the reaction terms to zero if the concentration is below the small threshold ɛ, introduces a substantial shift in the propagation speed of the corresponding travelling waves. In this paper, we prove the conjecture of Brunet and Derrida, showing that the speed of propagation is given by c_crit(\\varepsilon)=2-{\\pi^2}/{(\\ln\\varepsilon)^2}+\\cal{O}((\\ln\\varepsilon)^{-3}) , as ɛ → 0, for a large class of cut-off functions. Moreover, we extend this result to a more general family of scalar reaction-diffusion equations with cut-off. The main mathematical techniques used in our proof are the geometric singular perturbation theory and the blow-up method, which lead naturally to the identification of the reasons for the logarithmic dependence of ccrit on ɛ as well as for the universality of the corresponding leading-order coefficient (π2).

  8. Epidemiological cut-off values for Flavobacterium psychrophilum MIC data generated by a standard test protocol.

    PubMed

    Smith, P; Endris, R; Kronvall, G; Thomas, V; Verner-Jeffreys, D; Wilhelm, C; Dalsgaard, I

    2016-02-01

    Epidemiological cut-off values were developed for application to antibiotic susceptibility data for Flavobacterium psychrophilum generated by standard CLSI test protocols. The MIC values for ten antibiotic agents against Flavobacterium psychrophilum were determined in two laboratories. For five antibiotics, the data sets were of sufficient quality and quantity to allow the setting of valid epidemiological cut-off values. For these agents, the cut-off values, calculated by the application of the statistically based normalized resistance interpretation method, were ≤16 mg L(-1) for erythromycin, ≤2 mg L(-1) for florfenicol, ≤0.025 mg L(-1) for oxolinic acid (OXO), ≤0.125 mg L(-1) for oxytetracycline and ≤20 (1/19) mg L(-1) for trimethoprim/sulphamethoxazole. For ampicillin and amoxicillin, the majority of putative wild-type observations were 'off scale', and therefore, statistically valid cut-off values could not be calculated. For ormetoprim/sulphadimethoxine, the data were excessively diverse and a valid cut-off could not be determined. For flumequine, the putative wild-type data were extremely skewed, and for enrofloxacin, there was inadequate separation in the MIC values for putative wild-type and non-wild-type strains. It is argued that the adoption of OXO as a class representative for the quinolone group would be a valid method of determining susceptibilities to these agents.

  9. Calculating broad neutron resonances in a cut-off Woods-Saxon potential

    NASA Astrophysics Data System (ADS)

    Baran, Á.; Noszály, Cs.; Salamon, P.; Vertse, T.

    2015-07-01

    In a cut-off Woods-Saxon (CWS) potential with realistic depth S -matrix poles being far from the imaginary wave number axis form a sequence where the distances of the consecutive resonances are inversely proportional with the cut-off radius value, which is an unphysical parameter. Other poles lying closer to the imaginary wave number axis might have trajectories with irregular shapes as the depth of the potential increases. Poles being close repel each other, and their repulsion is responsible for the changes of the directions of the corresponding trajectories. The repulsion might cause that certain resonances become antibound and later resonances again when they collide on the imaginary axis. The interaction is extremely sensitive to the cut-off radius value, which is an apparent handicap of the CWS potential.

  10. A New Regularization Mechanism for the Boltzmann Equation Without Cut-Off

    NASA Astrophysics Data System (ADS)

    Silvestre, Luis

    2016-11-01

    We apply recent results on regularity for general integro-differential equations to derive a priori estimates in Hölder spaces for the space homogeneous Boltzmann equation in the non cut-off case. We also show an a priori estimate in {L^∞} which applies in the space inhomogeneous case as well, provided that the macroscopic quantities remain bounded.

  11. The INTEGRAL high energy cut-off distribution of Seyfert galaxies

    NASA Astrophysics Data System (ADS)

    Malizia, Angela; Ubertini, Pietro; Bird, Antony; Bazzano, Angela; Stephen, John; Molina, Manuela; Bassani, Loredana

    We present the primary continuum parameters, the photon index and the high energy cut-off, of Seyfert galaxies extracted from the INTEGRAL complete sample of AGN. We performed a broad band (0.3-100 keV) spectral analysis by fitting simultaneously the soft and hard X-ray spectra obtained by XMM and INTEGRAL/IBIS-Swift/BAT respectively in order to investigate the general properties of these parameters in particular their distribution and mean values. We present the mean photon index for the t type 1 and type 2 objects of the whole sample as well as their mean high energy cut-off. This is the first time that the cut-off energy is constrained in a such large number of AGN. Using the main parameters of the primary continuum, we are able to obtain the actual physical parameters of the Comptonizing region i.e. the plasma temperature kTe the optical depth tau. Finally, with the high S/N spectra starting to come from NuSTAR it will soon be possible to better constrain the cut-off values in many AGN, allowing the determination of more physical models and so to better understand the continuum emission and geometry of the region surrounding black holes.

  12. 76 FR 35378 - Installation and Use of Engine Cut-Off Switches on Recreational Vehicles

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-06-17

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF HOMELAND SECURITY Coast Guard 33 CFR Parts 175 and 183 RIN 1825-AB34 Installation and Use of Engine Cut-Off Switches on Recreational Vehicles Correction Proposed Rule document 2011-14140 was inadvertently published...

  13. Starting the polypill: the use of a single age cut-off in males and females.

    PubMed

    Wald, Nicholas J; Luteijn, Johannes M; Morris, Joan K

    2017-03-01

    Objective Age screening and preventive medication for future myocardial infarction and stroke has been previously described. We aimed to ascertain whether different age cut-offs are needed for males and females. Methods We determined five parameters for each sex according to age cut-off: detection rate (sensitivity), false-positive rate, proportion of the population eligible for treatment with a polypill, proportion who benefit from taking a polypill (simvastatin 20 mg, losartan 25 mg, hydrochlorothiazide 12.5 mg, amlodipine 2.5 mg), and among these, years of life gained without a first myocardial infarction or stroke. Results Approximately one-third benefit, regardless of the age cut-off. For males and females combined, using ages 40 and 80, the detection rates are 98% and 52%, false-positive rates are 51% and 7%, population percentages eligible for treatment are 52% and 7%, and years of life gained without a first myocardial infarction or stroke are 8.4 and 3.6. Using age 50, detection rates are 93% (males) 98% (females), false-positive rates 37% (males) 40% (females), percentage of the population eligible for treatment 38% (males) 41% (females), percentage who benefit 35% (males) 33% (females), and years of life gained without an event 8.5 (males) 7.0 (females). At a given age cut-off, the sex differences are relatively small. Conclusion A single age cut-off can be used for both sexes.

  14. Starting the polypill: the use of a single age cut-off in males and females

    PubMed Central

    Luteijn, Johannes M; Morris, Joan K

    2016-01-01

    Objective Age screening and preventive medication for future myocardial infarction and stroke has been previously described. We aimed to ascertain whether different age cut-offs are needed for males and females. Methods We determined five parameters for each sex according to age cut-off: detection rate (sensitivity), false-positive rate, proportion of the population eligible for treatment with a polypill, proportion who benefit from taking a polypill (simvastatin 20 mg, losartan 25 mg, hydrochlorothiazide 12.5 mg, amlodipine 2.5 mg), and among these, years of life gained without a first myocardial infarction or stroke. Results Approximately one-third benefit, regardless of the age cut-off. For males and females combined, using ages 40 and 80, the detection rates are 98% and 52%, false-positive rates are 51% and 7%, population percentages eligible for treatment are 52% and 7%, and years of life gained without a first myocardial infarction or stroke are 8.4 and 3.6. Using age 50, detection rates are 93% (males) 98% (females), false-positive rates 37% (males) 40% (females), percentage of the population eligible for treatment 38% (males) 41% (females), percentage who benefit 35% (males) 33% (females), and years of life gained without an event 8.5 (males) 7.0 (females). At a given age cut-off, the sex differences are relatively small. Conclusion A single age cut-off can be used for both sexes. PMID:27072544

  15. Multiple Sclerosis Questionnaire for Job Difficulties (MSQ-Job): definition of the cut-off score.

    PubMed

    Schiavolin, Silvia; Giovannetti, Ambra Mara; Leonardi, Matilde; Brenna, Greta; Brambilla, Laura; Confalonieri, Paolo; Frangiamore, Rita; Mantegazza, Renato; Moscatelli, Marco; Clerici, Valentina Torri; Cortese, Francesca; Covelli, Venusia; Ponzio, Michela; Zaratin, Paola; Raggi, Alberto

    2016-05-01

    Multiple Sclerosis (MS) mainly affects people of working age. The Multiple Sclerosis Questionnaire for Job Difficulties (MSQ-Job) was designed to measure difficulties in work-related tasks. Our aim is to define cut-off score of MSQ-Job to identify potential critical situations that might require specific attention. A sample of patients with MS completed the MSQ-Job, WHODAS 2.0 and MSQOL-54 respectively for work difficulties, disability and health-related quality of life (HRQoL) evaluation. K-means Cluster Analysis was used to divide the sample in three groups on the basis of HRQoL and disability. ANOVA test was performed to compare the response pattern between these groups. The cut-off score was defined using the receiver operating characteristic (ROC) curve analyses for MSQ-Job total and count of MSQ-Job items scores ≥3: a score value corresponding to the maximum of the sensitivity-to-specificity ratio was chosen as the cut-off. Out of 180 patients enrolled, twenty were clustered in the higher severity group. The area under the ROC curve was 0.845 for the MSQ-Job total and 0.859 for the count of MSQ-Job items scores ≥3 while the cut-off score was 15.8 for MSQ-Job total and 8 for count of items scored ≥3. We recommend the use of MSQ-Job with this calculation as cut-off for identifying critical situations, e.g. in vocational rehabilitation services, where work-related difficulties have a significant impact in terms of lower quality of life and higher disability.

  16. THE INTEGRAL HIGH-ENERGY CUT-OFF DISTRIBUTION OF TYPE 1 ACTIVE GALACTIC NUCLEI

    SciTech Connect

    Malizia, A.; Molina, M.; Bassani, L.; Stephen, J. B.; Bazzano, A.; Ubertini, P.; Bird, A. J.

    2014-02-20

    In this Letter we present the primary continuum parameters, the photon index Γ, and the high-energy cut-off E {sub c} of 41 type-1 Seyfert galaxies extracted from the International Gamma-Ray Astrophysics Laboratory (INTEGRAL) complete sample of active galactic nuclei (AGNs). We performed broadband (0.3-100 keV) spectral analysis by simultaneously fitting the soft and hard X-ray spectra obtained by XMM and INTEGRAL/IBIS-Swift/BAT, respectively, in order to investigate the general properties of these parameters, in particular their distribution and mean values. We find a mean photon index of 1.73 with a standard deviation of 0.17 and a mean high-energy cut-off of 128 keV with a standard deviation of 46 keV for the whole sample. This is the first time that the cut-off energy is constrained in such a large number of AGNs. We have 26 measurements of the cut-off, which corresponds to 63% of the entire sample, distributed between 50 and 200 keV. There are a further 11 lower limits mostly below 300 keV. Using the main parameters of the primary continuum, we have been able to obtain the actual physical parameters of the Comptonizing region, i.e., the plasma temperature kT {sub e} from 20 to 100 keV and the optical depth τ < 4. Finally, with the high signal-to-noise ratio spectra starting to come from NuSTAR it will soon be possible to better constrain the cut-off values in many AGNs, allowing the determination of more physical models and thus better understand the continuum emission and geometry of the region surrounding black holes.

  17. The INTEGRAL High-energy Cut-off Distribution of Type 1 Active Galactic Nuclei

    NASA Astrophysics Data System (ADS)

    Malizia, A.; Molina, M.; Bassani, L.; Stephen, J. B.; Bazzano, A.; Ubertini, P.; Bird, A. J.

    2014-02-01

    In this Letter we present the primary continuum parameters, the photon index Γ, and the high-energy cut-off E c of 41 type-1 Seyfert galaxies extracted from the International Gamma-Ray Astrophysics Laboratory (INTEGRAL) complete sample of active galactic nuclei (AGNs). We performed broadband (0.3-100 keV) spectral analysis by simultaneously fitting the soft and hard X-ray spectra obtained by XMM and INTEGRAL/IBIS-Swift/BAT, respectively, in order to investigate the general properties of these parameters, in particular their distribution and mean values. We find a mean photon index of 1.73 with a standard deviation of 0.17 and a mean high-energy cut-off of 128 keV with a standard deviation of 46 keV for the whole sample. This is the first time that the cut-off energy is constrained in such a large number of AGNs. We have 26 measurements of the cut-off, which corresponds to 63% of the entire sample, distributed between 50 and 200 keV. There are a further 11 lower limits mostly below 300 keV. Using the main parameters of the primary continuum, we have been able to obtain the actual physical parameters of the Comptonizing region, i.e., the plasma temperature kT e from 20 to 100 keV and the optical depth τ < 4. Finally, with the high signal-to-noise ratio spectra starting to come from NuSTAR it will soon be possible to better constrain the cut-off values in many AGNs, allowing the determination of more physical models and thus better understand the continuum emission and geometry of the region surrounding black holes.

  18. 40 CFR 53.53 - Test for flow rate accuracy, regulation, measurement accuracy, and cut-off.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... measurement accuracy, coefficient of variability measurement accuracy, and the flow rate cut-off function. The... flow measurements are made at intervals not to exceed 5 minutes. The flow rate cut-off test, conducted... definitions. (1) Sample flow rate means the quantitative volumetric flow rate of the air stream caused by...

  19. 40 CFR 53.53 - Test for flow rate accuracy, regulation, measurement accuracy, and cut-off.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... measurement accuracy, coefficient of variability measurement accuracy, and the flow rate cut-off function. The... flow measurements are made at intervals not to exceed 5 minutes. The flow rate cut-off test, conducted... definitions. (1) Sample flow rate means the quantitative volumetric flow rate of the air stream caused by...

  20. 40 CFR 53.53 - Test for flow rate accuracy, regulation, measurement accuracy, and cut-off.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... measurement accuracy, coefficient of variability measurement accuracy, and the flow rate cut-off function. The... flow measurements are made at intervals not to exceed 5 minutes. The flow rate cut-off test, conducted... definitions. (1) Sample flow rate means the quantitative volumetric flow rate of the air stream caused by...

  1. 40 CFR 53.53 - Test for flow rate accuracy, regulation, measurement accuracy, and cut-off.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... measurement accuracy, coefficient of variability measurement accuracy, and the flow rate cut-off function. The... flow measurements are made at intervals not to exceed 5 minutes. The flow rate cut-off test, conducted... definitions. (1) Sample flow rate means the quantitative volumetric flow rate of the air stream caused by...

  2. 40 CFR 53.53 - Test for flow rate accuracy, regulation, measurement accuracy, and cut-off.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... measurement accuracy, coefficient of variability measurement accuracy, and the flow rate cut-off function. The... flow measurements are made at intervals not to exceed 5 minutes. The flow rate cut-off test, conducted... definitions. (1) Sample flow rate means the quantitative volumetric flow rate of the air stream caused by...

  3. Treatment of amitriptyline intoxications by extended high cut-off dialysis.

    PubMed

    Schmidt, Julius J; Bertram, Anna; Kühn-Velten, W Nikolaus; Suhling, Hendrik; Wiesner, Olaf; Schneider, Andrea; Kielstein, Jan T

    2015-12-01

    Antidepressants, especially amitriptyline, are among the most frequent drug classes involved in intoxications. Despite its small molecular weight, amitriptyline is not considered to be eliminated by extracorporeal treatment methods due to its high protein binding and large volume of distribution. New high cut-off dialysers have so far not been used for removal of amitriptyline. We report two cases of amitriptyline poisoning in which we measured the amitriptyline elimination using extended high cut-off (HCO) dialysis. Despite dialyser clearances of 33 and 58 mL/min, resulting in the reduction of initial serum concentrations by ∼30%, only 211 and 920 µg of amitryptilin, respectively, (<3% of the ingested amount) could be recovered in the total collected dialysate. Hence, due to the high volume of distribution of amitriptyline, even HCO dialysis does not contribute substantially to the extracorporeal removal of amitryptilin.

  4. Treatment of amitriptyline intoxications by extended high cut-off dialysis

    PubMed Central

    Schmidt, Julius J.; Bertram, Anna; Kühn-Velten, W. Nikolaus; Suhling, Hendrik; Wiesner, Olaf; Schneider, Andrea; Kielstein, Jan T.

    2015-01-01

    Antidepressants, especially amitriptyline, are among the most frequent drug classes involved in intoxications. Despite its small molecular weight, amitriptyline is not considered to be eliminated by extracorporeal treatment methods due to its high protein binding and large volume of distribution. New high cut-off dialysers have so far not been used for removal of amitriptyline. We report two cases of amitriptyline poisoning in which we measured the amitriptyline elimination using extended high cut-off (HCO) dialysis. Despite dialyser clearances of 33 and 58 mL/min, resulting in the reduction of initial serum concentrations by ∼30%, only 211 and 920 µg of amitryptilin, respectively, (<3% of the ingested amount) could be recovered in the total collected dialysate. Hence, due to the high volume of distribution of amitriptyline, even HCO dialysis does not contribute substantially to the extracorporeal removal of amitryptilin. PMID:26613042

  5. Edge plasmons and cut-off behavior of graphene nano-ribbon waveguides

    NASA Astrophysics Data System (ADS)

    Hou, Haowen; Teng, Jinghua; Palacios, Tomás; Chua, Soojin

    2016-07-01

    Graphene nano-ribbon waveguides with ultra-short plasmon wavelength are a promising candidate for nanoscale photonic applications. Graphene edge plasmons are the fundamental and lowest losses mode. Through finite element method, edge plasmons show large effective refractive index and strong field confinement on nanoscale ribbons. The edge plasmons follow a k1/2 dispersion relation. The wavelengths of the edge plasmons and center plasmons differ by a fixed factor. The width of edge plasmon is inversely proportional to wave vector of edge plasmon kedge. Edge defects associate with graphene nano-ribbon induce extra losses and reduce the propagation length. Cut-off width of edge plasmons reduces with increasing frequency. Cut-off width of center plasmon is enlarged by edge component but the enlargement effect diminishing with the increase of kedge. The results are important for the application of graphene plasmon towards ultra-compact photonic devices.

  6. "Cut-off" effect of antioxidants and/or probes of variable lipophilicity in microheterogeneous media.

    PubMed

    Aliaga, Carolina; López de Arbina, Amaia; Rezende, Marcos Caroli

    2016-09-01

    The activities of two hydrophilic (ascorbic acid and Trolox) and two hydrophobic (α-tocopherol and BHT) antioxidants were measured by reaction with a series of 4-alkanoyloxyTEMPO radical probes 1 in buffered (pH 7), aqueous, micellar solutions of reduced Triton-X 100. In all cases, a cut-off effect was observed, in line with previous observations of the same effect for the partitioning of probe series 1 in this medium. These results support an interpretation of the cut-off effect in food emulsions, based on the "amphiphobic" nature of either the antioxidants or probes: competition between two molecular moieties, for the micellar hydrophobic core, tends to expose a reacting fragment differently to a more hydrophilic microenvironment, as the probe or antioxidant hydrophobicity increases.

  7. Solutions to the 1d Klein Gordon equation with cut-off Coulomb potentials

    NASA Astrophysics Data System (ADS)

    Hall, Richard L.

    2007-12-01

    In a recent paper by Barton [G. Barton, J. Phys. A: Math. Gen. 40 (2007) 1011], the 1-dimensional Klein Gordon equation was solved analytically for the non-singular Coulomb-like potential V(|x|)=-α/(|x|+a). In the present Letter, these results are completely confirmed by a numerical formulation that also allows a solution for an alternative cut-off Coulomb potential V(|x|)=-α/|x|, |x|>a, and otherwise V(|x|)=-α/a.

  8. Evaluation of Novel Large Cut-Off Ultrafiltration Membranes for Adenovirus Serotype 5 (Ad5) Concentration

    PubMed Central

    Peixoto, Cristina; Roederstein, Susanne; Schleuss, Tobias; Alves, Paula M.; Mota, José P. B.; Carrondo, Manuel J. T.

    2014-01-01

    The purification of virus particles and viral vectors for vaccine and gene therapy applications is gaining increasing importance in order to deliver a fast, efficient, and reliable production process. Ultrafiltration (UF) is a widely employed unit operation in bioprocessing and its use is present in several steps of the downstream purification train of biopharmaceuticals. However, to date few studies have thoroughly investigated the performance of several membrane materials and cut-offs for virus concentration/diafiltration. The present study aimed at developing a novel class of UF cassettes for virus concentration/diafiltration. A detailed study was conducted to evaluate the effects of (i) membrane materials, namely polyethersulfone (PES), regenerated cellulose (RC), and highly cross-linked RC (xRC), (ii) nominal cut-off, and (iii) UF device geometry at different production scales. The results indicate that the xRC cassettes with a cut-off of approximately 500 kDa are able to achieve a 10-fold concentration factor with 100% recovery of particles with a process time twice as fast as that of a commercially available hollow fiber. DNA and host cell protein clearances, as well as hydraulic permeability and fouling behavior, were also assessed. PMID:25546428

  9. Clustered star formation as a natural explanation for the Halpha cut-off in disk galaxies.

    PubMed

    Pflamm-Altenburg, Jan; Kroupa, Pavel

    2008-10-02

    The rate of star formation in a galaxy is often determined by the observation of emission in the Halpha line, which is related to the presence of short-lived massive stars. Disk galaxies show a strong cut-off in Halpha radiation at a certain galactocentric distance, which has led to the conclusion that star formation is suppressed in the outer regions of disk galaxies. This is seemingly in contradiction to recent observations in the ultraviolet which imply that disk galaxies have star formation beyond the Halpha cut-off, and that the star-formation-rate surface density is linearly related to the underlying gas surface density, which is a shallower relationship than that derived from Halpha luminosities. In a galaxy-wide formulation, the clustered nature of star formation has recently led to the insight that the total galactic Halpha luminosity is nonlinearly related to the galaxy-wide star formation rate. Here we show that a local formulation of the concept of clustered star formation naturally leads to a steeper radial decrease in the Halpha surface luminosity than in the star-formation-rate surface density, in quantitative agreement with the observations, and that the observed Halpha cut-off arises naturally.

  10. Cut-off proposal for the detection of ketamine in hair.

    PubMed

    Salomone, A; Gerace, E; Diana, P; Romeo, M; Malvaso, V; Di Corcia, D; Vincenti, M

    2015-03-01

    Ketamine is a powerful anesthetic drug used in both human and veterinary surgery, but it is also commonly misused because of its psychotropic properties. Since the abuse of this drug has been reported in many countries worldwide, its determination in hair samples is offered as a specialist test by hundreds of laboratories. However, unlike other common drugs of abuse, a cut-off level for ketamine in hair has not been fixed yet. Therefore, aim of this study is to propose a concentration value for ketamine in hair analysis, in order to discriminate between chronic and occasional use, and between active use and external contamination. After considering the chemical properties of this molecule, and the experimental data collected in our laboratory or reported in several other published studies, we propose a cut-off level of 0.5ng/mg, as indicative of repeated exposure to ketamine. Additionally, we suggest that the detection of the metabolite norketamine should be mandatory to prove active intake and exclude false positive result from external contamination. Thus, a reasonable cut-off value for norketamine could be fixed at 0.1ng/mg, while the minimal concentration ratio norketamine/ketamine may be positively established at 0.05.

  11. A review of the cut-off points for the diagnosis of vitamin B12 deficiency in the general population.

    PubMed

    Aparicio-Ugarriza, Raquel; Palacios, Gonzalo; Alder, Monika; González-Gross, Marcela

    2015-07-01

    Vitamin B12 deficit is one of the most common vitamin deficiencies. However, there is no consensus on the cut-off points for vitamin B12 and its co-markers, such as folate, holotranscobalamin, methylmalonic acid and homocysteine. In order to establish the state of the art about cut-off points used to determine vitamin B12 deficiency in the last decades, the database MEDLINE was used for searching studies published in adults between December 1992 and May 2014 (69 articles), using search terms like 'vitamin B12', 'cobalamin', 'cut-off', 'deficiency' alone or in combinations. Broad ranges of cut-off points for vitamin B12 and its biomarkers were identified: vitamin B12 ranged between 100 pmol/L and 350 pmol/L, holotranscobalamin 20-50 pmol/L, methylmalonic acid 0.210-0.470 μmol/L, homocysteine 10-21.6 μmol/L, serum folate 3.7-15.9 nmol/L and red blood cell 124-397 nmol/L. For the majority of studies, the potential influence of age, analytical methods, gender and fortified food consumption was not taken in account when choosing cut-off values. This could explain the discrepancies between studies on vitamin B12 and folate deficiency prevalences. We conclude that there is inconsistency in the literature regarding vitamin B12 cut-offs. It would be necessary to establish different reference cut-offs according to age, considering the analytical methods used.

  12. Defining a BMI Cut-Off Point for the Iranian Population: The Shiraz Heart Study

    PubMed Central

    Babai, Mohammad Ali; Arasteh, Peyman; Hadibarhaghtalab, Maryam; Naghizadeh, Mohammad Mehdi; Salehi, Alireza; Askari, Alireza; Homayounfar, Reza

    2016-01-01

    In this study we evaluated and redefined the optimum body mass index (BMI) cut-off point for the Iranian population based on metabolic syndrome (MeS) risk factors. We further evaluated BMI cut-off points with and without waist circumference (WC) as a cofactor of risk and compared the differences. This study is part of the largest surveillance programs conducted in Shiraz, Iran, termed the Shiraz Heart study. Our study sample included subjects between the ages of 20 to 65 years old. After excluding pregnant women, those with missing data and those with comorbid disease, a total of 12283 made up the study population. The participants underwent a series of tests and evaluations by trained professionals in accordance with WHO recommendations. Hypertension, abnormal fasting blood sugar (FBS), triglyceride (TG) and high density lipoprotein cholesterol (HDL) (in the context of the definition of metabolic syndrome) were prevalent among 32.4%, 27.6%, 42.1 and 44.2% of our participants, respectively. Women displayed higher rates of overall obesity compared to men (based on the definition by the WHO as higher than 30 kg/m2). Regarding MeS, 38.9% of our population had the all symptoms of MeS which was more prevalent among women (41.5% vs. 36%). When excluding WC in the definition of MeS, results showed that males tend to show a higher rate of metabolic risk factors (19.2% vs. 15.6%). Results of multivariate analysis showed that parallel to an increase in BMI, the odds ratio (OR) for acquiring each component of the metabolic syndrome increased (OR = 1.178; CI: 1.166–1.190). By excluding WC, the previous OR decreased (OR = 1.105; CI: 1.093–1.118). Receiver Operating Characteristic (ROC) curve analysis showed that the optimum BMI cut-off point for predicting metabolic syndrome was 26.1 kg/m2 and 26.2 kg/m2 [Accuracy (Acc) = 69% and 61%, respectively)] for males and females, respectively. The overall BMI cut-off for both sexes was 26.2 kg/m2 (Acc = 65%) with sensitivity and

  13. Cut-off wavenumber of Alfvén waves in partially ionized plasmas of the solar atmosphere

    NASA Astrophysics Data System (ADS)

    Zaqarashvili, T. V.; Carbonell, M.; Ballester, J. L.; Khodachenko, M. L.

    2012-08-01

    Context. Alfvén wave dynamics in partially ionized plasmas of the solar atmosphere shows that there is indeed a cut-off wavenumber, i.e. the Alfvén waves with wavenumbers higher than the cut-off value are evanescent. The cut-off wavenumber appears in single-fluid magnetohydrodynamic (MHD) approximation but it is absent in a multi-fluid approach. Up to now, an explanation for the existence of the cut-off wavenumber is still missing. Aims: The aim of this paper is to point out the reason for the appearance of a cut-off wavenumber in single-fluid MHD. Methods: Beginning with three-fluid equations (with electrons, protons and neutral hydrogen atoms), we performed consecutive approximations until we obtained the usual single-fluid description. We solved the dispersion relation of linear Alfvén waves at each step and sought the approximation responsible of the cut-off wavenumber appearance. Results: We have found that neglecting inertial terms significantly reduces the real part of the Alfvén frequency although it never becomes zero. Therefore, the cut-off wavenumber does not exist at this stage. However, when the inertial terms together with the Hall term in the induction equation are neglected, the real part of the Alfvén frequency becomes zero. Conclusions: The appearance of a cut-off wavenumber, when Alfvén waves in partially ionized regions of the solar atmosphere are studied, is the result of neglecting inertial and Hall terms, therefore it has no physical origin.

  14. Comparing Approaches to Optimize Cut-off Scores for Short Cognitive Screening Instruments in Mild Cognitive Impairment and Dementia

    PubMed Central

    O’Caoimh, Rónán; Gao, Yang; Svendovski, Anton; Gallagher, Paul; Eustace, Joseph; Molloy, D. William

    2017-01-01

    Background: Although required to improve the usability of cognitive screening instruments (CSIs), the use of cut-off scores is controversial yet poorly researched. Objective: To explore cut-off scores for two short CSIs: the Standardized Mini-Mental State Examination (SMMSE) and Quick Mild Cognitive Impairment (Qmci) screen, describing adjustments in scores for diagnosis (MCI or dementia), age (≤, >75 years), and education (<, ≥12 years), comparing two methods: the maximal accuracy approach, derived from receiver operating characteristic curves, and Youden’s Index. Methods: Pooled analysis of assessments from patients attending memory clinics in Canada between 1999–2010 : 766 with mild cognitive impairment (MCI) and 1,746 with dementia, and 875 normal controls. Results: The Qmci was more accurate than the SMMSE in differentiating controls from MCI or cognitive impairment (MCI and dementia). Employing the maximal accuracy approach, the optimal SMMSE cut-off for cognitive impairment was <28/30 (AUC 0.86, sensitivity 74%, specificity 88%) versus <63/100 for the Qmci (AUC 0.93, sensitivity 85%, specificity 85%). Using Youden’s Index, the optimal SMMSE cut-off remained <28/30 but fell slightly to <62/100 for the Qmci (sensitivity 83%, specificity 87%). The optimal cut-off for MCI was <29/30 for the SMMSE and <67/100 for the Qmci, irrespective of technique. The maximal accuracy approach generally produced higher Qmci cut-offs than Youden’s Index, both requiring adjustment for age and education. There were no clinically meaningful differences in SMMSE cut-off scores by age and education or method employed. Conclusion: Caution should be exercised selecting cut-offs as these differ by age, education, and method of derivation, with the extent of adjustment varying between CSIs. PMID:28222528

  15. Enhanced trans-Himalaya pollution transport to the Tibetan Plateau by cut-off low systems

    NASA Astrophysics Data System (ADS)

    Zhang, Ruixiong; Wang, Yuhang; He, Qiusheng; Chen, Laiguo; Zhang, Yuzhong; Qu, Hang; Smeltzer, Charles; Li, Jianfeng; Alvarado, Leonardo M. A.; Vrekoussis, Mihalis; Richter, Andreas; Wittrock, Folkard; Burrows, John P.

    2017-02-01

    Long-range transport followed by deposition of black carbon on glaciers of Tibet is one of the key issues of climate research as it induces changes on radiative forcing and subsequently impacting the melting of glaciers. The transport mechanism, however, is not well understood. In this study, we use short-lived reactive aromatics as proxies to diagnose transport of pollutants to Tibet. In situ observations of short-lived reactive aromatics across the Tibetan Plateau are analyzed using a regional chemistry and transport model. The model performance using the current emission inventories over the region is poor due to problems in the inventories and model transport. Top-down emissions constrained by satellite observations of glyoxal are a factor of 2-6 higher than the a priori emissions over the industrialized Indo-Gangetic Plain. Using the top-down emissions, agreement between model simulations and surface observations of aromatics improves. We find enhancements of reactive aromatics over Tibet by a factor of 6 on average due to rapid transport from India and nearby regions during the presence of a high-altitude cut-off low system. Our results suggest that the cut-off low system is a major pathway for long-range transport of pollutants such as black carbon. The modeling analysis reveals that even the state-of-the-science high-resolution reanalysis cannot simulate this cut-off low system accurately, which probably explains in part the underestimation of black carbon deposition over Tibet in previous modeling studies. Another model deficiency of underestimating pollution transport from the south is due to the complexity of terrain, leading to enhanced transport. It is therefore challenging for coarse-resolution global climate models to properly represent the effects of long-range transport of pollutants on the Tibetan environment and the subsequent consequence for regional climate forcing.

  16. Cut-off values of blessed dementia rating scale and its clinical application in elderly Taiwanese.

    PubMed

    Yang, Yuan-Han; Lai, Chiou-Lian; Lin, Ruey-Tay; Tai, Chih-Ta; Liu, Ching-Kuan

    2006-08-01

    Although the Blessed Dementia Rating Scale (BDRS), a clinical screening instrument, has been applied extensively, no suitable cut-off values and clinical application have been proposed, particularly in mild cognitive impairment (MCI), the precursor of dementia. The BDRS, Mini Mental State Examination (MMSE), and Clinical Dementia Rating Scale (CDR) were administrated in people aged 65 years and above, who were enrolled from southern Taiwan with multistep stratified random sampling and followed-up for 2 years. All subjects (total number = 3,027), with new onset of MCI (defined as CDR = 0.5) in the first year and dementia (defined as CDR > or = 1) in the second and third years were subjected to statistical analysis. In distinguishing normal from MCI, except in the literate group aged 65-74 years, MMSE was superior to BDRS, with cut-off values of 1 in both literate groups aged 65-74 years and > or = 75 years, and 1.5 and 2 in less educated groups aged 65-74 and > or = 75 years, respectively. In distinguishing MCI from dementia, BDRS had cut-off values of 2.5 in both literate groups aged 65-74 and > or = 75 years, and 2.5 and 3 in less educated groups aged 65-74 and > or = 75 years, respectively. These values were better than those for MMSE in all groups. BDRS might be considered as a better tool than MMSE to screen for MCI and dementia in the increasing proportion of literate elderly aged 65-74 years in the aging population.

  17. Revisiting AdS/CFT at a finite radial cut-off

    NASA Astrophysics Data System (ADS)

    Mandal, Gautam; Nayak, Pranjal

    2016-12-01

    We revisit AdS/CFT at a finite radial cut-off, specifically in the context of double trace perturbations, O_n=O(x){({partial}^2)}^nO(x) , with arbitrary powers n. As well-known, the standard GKPW prescription, applied to a finite radial cut-off, leads to contact terms in correlators. de Haro et al. [1] introduced bulk counterterms to remove these. This prescription, however, yields additional terms in the correlator corresponding to spurious double trace deformations. Further, if we view the GKPW prescription coupled with the prescription in [1], in terms of a boundary wavefunction, we find that it is incompatible with radial Schrödinger evolution (in the spirit of holographic Wilsonian RG). We consider a more general wavefunction satisfying the Schrödinger equation, and find that generically such wavefunctions generate both (a) double trace deformations and (b) contact terms. However, we find that there exist special choices of these wavefunctions, amounting to a new AdS/CFT prescription at a finite cut-off, so that both (a) and (b) are removed and we obtain a pure power law behaviour for the correlator. We compare these special wavefunctions with a specific RG scheme in field theory. We give a geometric interpretation of these wavefunctions; these correspond to some specific smearing of boundary points in the Witten diagrams. We present a comprehensive calculation of exact double-trace beta-functions for all couplings O_n and match with a holographic computation using the method described above. The matching works with a mapping between the field theory and bulk couplings; such a map is highly constrained because the beta-functions are quadratic and exact on both sides. Our discussions include a generalization of the standard double-trace Wilson-Fisher flow to the space of the infinite number of couplings.

  18. Optimised cut-off function for Tersoff-like potentials for a BN nanosheet: a molecular dynamics study

    NASA Astrophysics Data System (ADS)

    Kumar, Rajesh; Rajasekaran, G.; Parashar, Avinash

    2016-02-01

    In this article, molecular dynamics based simulations were carried out to study the tensile behaviour of boron nitride nanosheets (BNNSs). Four different sets of Tersoff potential parameters were used in the simulations for estimating the interatomic interactions between boron and nitrogen atoms. Modifications were incorporated in the Tersoff cut-off function to improve the accuracy of results with respect to fracture stress, fracture strain and Young’s modulus. In this study, the original cut-off function was optimised in such a way that small and large cut-off distances were made equal, and hence a single cut-off distance was used with all sets of Tersoff potential parameters. The single value of cut-off distance for the Tersoff potential was chosen after analysing the potential energy and bond forces experienced by boron and nitrogen atoms subjected to bond stretching. The simulations performed with the optimised cut-off function help in identifying the Tersoff potential parameters that reproduce the experimentally evaluated mechanical behaviour of BNNSs.

  19. Cut-off effect of radical TEMPO derivatives in olive oil-in-water emulsions.

    PubMed

    Lopez de Arbina, Amaia; Rezende, Marcos Caroli; Aliaga, Carolina

    2017-06-01

    Three oil-in-water emulsions were prepared from mixtures of olive oil and Tween 20 in water. The effectiveness of a series of radical 2,2,6,6-tetramethylpiperidinoxyl (TEMPO) derivatives of variable lipophilicity in reactions with antioxidant Trolox, and as pyrene-fluorescence quenchers, was compared in the three emulsions. A "cut-off" effect was observed for the pyrene quenching by the probes, but not for their reaction with Trolox. The results were rationalized in terms of the amphiphobic nature of the probes, and the different locations of probe, pyrene and Trolox in the three-phase microheterogeneous systems.

  20. Interstellar Flow Longitude from Pickup Ion Cut-off Observations at 1 AU

    NASA Astrophysics Data System (ADS)

    Moebius, E.; Lee, M. A.; Gloeckler, G.; Drews, C.

    2015-12-01

    The precise determination of the interstellar neutral (ISN) flow direction is important in several different ways. As a cardinal axis of the heliosphere it has strong leverage on the plane subtended by the ISN velocity and interstellar magnetic field vector, which controls the shape of the heliosphere and its interaction with the interstellar medium. The observation of the ISN flow through the heliosphere for several decades has initiated a discussion about potential temporal variations in the ISN flow. To tackle these questions, a precision measurement of the ISN flow velocity vector is needed over a long time period. Recent efforts to obtain a consistent ISN vector and temperature with Ulysses and IBEX point to remaining uncertainties and potential systematic effects. In particular, IBEX measurements provide a very precise relation between ISN flow longitude and speed via the hyperbolic trajectory equation, but they contain larger uncertainties separately for longitude and speed. Pickup ion (PUI) observations of the ISN flow pattern at 1 AU can provide a complementary determination of the flow longitude with high precision. The interstellar PUI cut-off speed is a function of the ratio of the radial ISN flow component and the solar wind speed at the observer location [Möbius et al., 1999, GRL, 26, 3181]. We have compared STEREO A PLASTIC observations with a simple analytic model of the cut-off and performed a Pearson correlation analysis of the cut-off as a function of ecliptic longitude with its mirrored function. The two complementary approaches demonstrate that the ISN flow longitude can be obtained with a precision on the order of 0.1o. The cut-off speed is much less sensitive to systematic effects on PUIs, such as variations in the solar wind parameters, ionization, and transport. ACE SWICS, STEREO PLASTIC, and SOHO CTOF data are available that span almost two decades, which will allow long term studies with high precision. The availability of O and Ne PUI

  1. Detection of stratosphere troposphere exchange in cut-off low systems

    NASA Technical Reports Server (NTRS)

    Price, Jeremy D.; Vaughan, Geraint

    1994-01-01

    The Aberystwyth MST radar has been used as part of the TOASTE program to study the structure of the tropopause in cut-off-low system with an aim to identifying regions where stratosphere-troposphere exchange are taking place. Theory predicts that the vertical gradient in reflected power is proportional to the static stability of the reflecting region, and should therefore resolve tropopause structure. Comparisons of MST power profiles with radiosonde data are presented and show good agreement, revealing regions of indefinite tropopauses, where stratosphere-troposphere exchange is thought to take place. The continuous nature of MST data allows an estimation of the size of these regions.

  2. Transaminase abnormalities and adaptations of the liver lobule manifest at specific cut-offs of steatosis

    PubMed Central

    Hall, Andrew; Covelli, Claudia; Manuguerra, Roberta; Luong, Tu Vinh; Buzzetti, Elena; Tsochatzis, Emmanuel; Pinzani, Massimo; Dhillon, Amar Paul

    2017-01-01

    There is little documented evidence suggesting that liver fat is responsible for liver injury in the absence of other disease processes. We investigated the relationships between liver fat, aminotransferases and hepatic architecture in liver biopsies with simple steatosis. We identified 136 biopsies with simple steatosis from the Royal Free Hospital Archives with both clinical data and sufficient material. Digital image analysis was employed to measure fat proportionate area (mFPA). Hepatocyte area (HA) and lobule radius (LR) were also measured. There were significant increases in ALT (p < 0.001) and AST (p = 0.013) with increased fat content and evidence to suggest both 5% and 20% mFPA as a cut-off for raised ALT. In liver with increased fat content there were significant increases in HA (p < 0.001). LR also increased as mFPA increased to 10% (p < 0.001), at which point the lobule ceased to expand further and was counterbalanced with a decrease in the number of hepatocytes per lobule (p = 0.029). Consequently there are mechanisms of adaption in the liver architecture to accommodate the accumulation of fat and these are accompanied by significant increases in transaminases. These results support the generally accepted cut-off of 5% fat for steatosis and indicate 20% as a threshold of more severe liver injury. PMID:28106158

  3. Cut-Off Values of Visceral Adiposity to Predict NAFLD in Brazilian Obese Adolescents

    PubMed Central

    Grotti Clemente, Ana Paula; Molin Netto, Bárbara Dal; Ganen, Aline di Piano; Tock, Lian; Arisa Caranti, Danielle; de Mello, Marco Túlio; Tufik, Sergio; Dâmaso, Ana R.

    2013-01-01

    Objectives. The present study aimed at determining cut-off points of visceral fat to predict NAFLD and analyzed metabolic disorders of obese adolescents. Methods. Cross-sectional study involved 165 obese adolescents ranged in age from 15 to 19 years. Glycemia, hepatic transaminases, lipid profile, and insulin resistance were analyzed. Visceral and subcutaneous fat were measured by ultrasound and body composition by plesthysmography. Results. The NAFLD adolescents had significantly higher values for body mass, BMI-for-age, BMI, total fat, waist circumference, and visceral fat when compared with non-NAFLD obese adolescents in both genders. Moreover, there were significant positive correlations between visceral fat with the variables BMI-for-age (r = 0.325,), TG (r = 0.277), AST (r = 0.509), ALT (r = 0.519), WC (r = 0.390), and visceral/subcutaneous ratio (r = 0.790) for NAFLD group. Total fat, triglycerides, and visceral fat were the independent predictors to NAFLD. Analysis of the ROC curves revealed cut-off points of visceral fat of 4.47 cm for girls and 4.21 cm for boys. Conclusions. The results may suggest that abdominal ultrasonography procedure may be a safe alternative method of assessing visceral adiposity aiming to be considered to the development of preventive and treatment strategies in obese individuals. This clinial trial is registered with ClinicalTrial.gov (NCT01358773). PMID:24381750

  4. Characterization of thermal cut-off mechanisms in prismatic lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Venugopal, Ganesh

    Lithium-ion (Li-ion) cells that are subjected to electrical abuse, overcharge and external short-circuit in particular, exhibit a rapid increase in cell temperature that could potentially lead to catastrophic disassembly of the cell. For this reason these cells are integrated or combined with one or more safety components that are designed to restrict or even prevent current flow through the cell under abusive conditions. In this work, the characteristics of these components in several prismatic Li-ion cells are studied by monitoring the impedance ( Z) at 1 kHz and the open circuit voltage (OCV) of the discharged cells as a function of temperature. All the cells studied were found to use polyethylene-based shutdown (SD) separators that were irreversibly activated within a narrow temperature range between 130 and 135°C. In some cells irreversible cut-off was also provided by a current interrupt device (CID) or a thermal fuse. Both these devices had a circuit-breaker effect, causing the impedance of the cell to rise infinitely and the OCV to drop to zero. In addition to these irreversible cut-off mechanisms, some cells also contained internal or external positive-temperature-coefficient (PTC) devices that could provide current-limiting capability over a very wide temperature range. The interdependence of the thermal behavior of these components on each other and on other thermally dependant processes like cell venting, separator meltdown and weld joint failure are also discussed.

  5. DAS28-CRP and DAS28-ESR cut-offs for high disease activity in rheumatoid arthritis are not interchangeable

    PubMed Central

    Fleischmann, Roy M; van der Heijde, Désirée; Gardiner, Philip V; Szumski, Annette; Marshall, Lisa; Bananis, Eustratios

    2017-01-01

    Background In most patients with rheumatoid arthritis (RA), Disease Activity Score 28-joint count C reactive protein (DAS28-CRP) is lower than DAS28 erythrocyte sedimentation rate (DAS28-ESR), suggesting that use of the DAS28-ESR cut-off to assess high disease activity (HDA) with DAS28-CRP may underestimate the number of patients with HDA. We determined the DAS28-CRP value corresponding to the validated DAS28-ESR cut-off for HDA. Methods Baseline data were pooled from 2 clinical studies evaluating etanercept (ETN) plus methotrexate (MTX) or MTX in early RA; DAS28-CRP and DAS28-ESR were obtained, allowing the determination of the DAS28-CRP HDA value best corresponding to the DAS28-ESR cut-off of >5.1. Results At baseline, as expected, fewer patients had HDA by DAS28-CRP than DAS28-ESR; DAS28-CRP>5.1 and DAS28-ESR>5.1 had only modest agreement (κ coefficients 0.45–0.54). Mean DAS28-CRP and DAS28-ESR were 5.7 and 6.2, respectively, in the ETN+MTX group (n=571), and 6.0 and 6.5 in the MTX group (n=262). A DAS28-CRP cut-off of 4.6 corresponded to a DAS28-ESR cut-off of 5.1. Conclusions We have shown that a DAS28-CRP of 4.6 corresponds to 5.1 for DAS28-ESR. Since this is substantially lower than the DAS28-ESR cut-off of 5.1, using 5.1 as the cut-off for DAS28-CRP underestimates disease activity in RA. Trial registration number NCT00195494; NCT00913458. PMID:28255449

  6. The Cut-off Values of Triglycerides and Glucose Index for Metabolic Syndrome in American and Korean Adolescents

    PubMed Central

    2017-01-01

    The aim of this study was to establish ethnic- and gender-specific cut-off values of triglycerides and glucose index (TyG index) for clinical usefulness in a representative sample of Mexican American, Non-Hispanic White, Non-Hispanic Black, and Korean adolescents. The data were collected from datasets of the National Health and Nutrition Examination Survey between 1999 and 2012, and the Korean National Health and Nutrition Examination Survey between 2005 and 2013. Receiver operating characteristic curve analysis was used to find valid cut-off values of the TyG index for metabolic syndrome. The total number of eligible participants was 3,164 in the US and 4,873 in Korea. The optimal cut-off value with the Cook et al. definition revealed 8.55 in Mexican American, 8.55 in Non-Hispanic White, 8.35 in Non-Hispanic Black, and 8.45 in Korean, respectively. The cut-off value with the de Ferranti et al. definition was 8.45, 8.45, 8.15, and 8.35, and the cut-off value with the International Diabetes Federation definition was 8.65, 8.65, 8.15, and 8.55, respectively. These findings may be clinically useful for evaluating insulin resistance for determining metabolic abnormalities in adolescents. PMID:28145645

  7. Determination of hair ketamine cut-off value from Hong Kong ketamine users by LC-MS/MS analysis.

    PubMed

    Leung, K Wing; Wong, Zack C F; Ho, Janet Y M; Yip, Ada W S; Ng, Jenny S C; Ip, Stanley P H; Ng, Winki Y Y; Ho, Karen K L; Duan, Ran; Zhu, Kevin Y; Tsim, Karl W K

    2016-02-01

    Ketamine is one of the most frequent abused drugs in Hong Kong and South-East Asia, and the cases of ketamine abused have been reported worldwide. Hair has been commonly used as a specimen for the proof of chronic drug abused because of its non-invasiveness and long detection windows. The determinations of ketamine in hair with varieties of state-of-the-art instruments and detection methods have been developed in the past decade; however, the cut-off value for ketamine abuser has not been developed according to the international guidelines. The aim of this study is to propose a cut-off value for ketamine in hair by analyzing ketamine and its metabolite norketamine by LC-MS/MS method in a population of ketamine users in Hong Kong. The limit of detection (LOD) and limit of quantification (LOQ) for ketamine and norketamine were 20pg/mg and 100pg/mg, respectively. From 977 ketamine abusers, the cut-off value for ketamine in hair was proposed to be 400pg/mg of hair. This proposed cut-off value is the concentration of hair ketamine when over 90% of samples are being detected with the presence of norketamine, which is a proof of ketamine abuse. This value could be applied as a screening or occupational cut-off for reference.

  8. Cut-off characterisation of energy spectra of bright fermi sources: Current instrument limits and future possibilities

    NASA Astrophysics Data System (ADS)

    Romoli, C.; Taylor, A. M.; Aharonian, F.

    2017-02-01

    In this paper some of the brightest GeV sources observed by the Fermi-LAT were analysed, focusing on their spectral cut-off region. The sources chosen for this investigation were the brightest blazar flares of 3C 454.3 and 3C 279 and the Vela pulsar with a reanalysis with the latest Fermi-LAT software. For the study of the spectral cut-off we first explored the Vela pulsar spectrum, whose statistics in the time interval of the 3FGL catalog allowed strong constraints to be obtained on the parameters. We subsequently performed a new analysis of the flaring blazar SEDs. For these sources we obtained constraints on the cut-off parameters under the assumption that their underlying spectral distribution is described by a power-law with a stretched exponential cut-off. We then highlighted the significant potential improvements on such constraints by observations with next generation ground based Cherenkov telescopes, represented in our study by the Cherenkov Telescope Array (CTA). Adopting currently available simulations for this future observatory, we demonstrate the considerable improvement in cut-off constraints achievable by observations with this new instrument when compared with that achievable by satellite observations.

  9. The Cut-off Values of Triglycerides and Glucose Index for Metabolic Syndrome in American and Korean Adolescents.

    PubMed

    Moon, Shinje; Park, Joon Sung; Ahn, Youhern

    2017-03-01

    The aim of this study was to establish ethnic- and gender-specific cut-off values of triglycerides and glucose index (TyG index) for clinical usefulness in a representative sample of Mexican American, Non-Hispanic White, Non-Hispanic Black, and Korean adolescents. The data were collected from datasets of the National Health and Nutrition Examination Survey between 1999 and 2012, and the Korean National Health and Nutrition Examination Survey between 2005 and 2013. Receiver operating characteristic curve analysis was used to find valid cut-off values of the TyG index for metabolic syndrome. The total number of eligible participants was 3,164 in the US and 4,873 in Korea. The optimal cut-off value with the Cook et al. definition revealed 8.55 in Mexican American, 8.55 in Non-Hispanic White, 8.35 in Non-Hispanic Black, and 8.45 in Korean, respectively. The cut-off value with the de Ferranti et al. definition was 8.45, 8.45, 8.15, and 8.35, and the cut-off value with the International Diabetes Federation definition was 8.65, 8.65, 8.15, and 8.55, respectively. These findings may be clinically useful for evaluating insulin resistance for determining metabolic abnormalities in adolescents.

  10. From Newton's Law to the Linear Boltzmann Equation Without Cut-Off

    NASA Astrophysics Data System (ADS)

    Ayi, Nathalie

    2017-03-01

    We provide a rigorous derivation of the linear Boltzmann equation without cut-off starting from a system of particles interacting via a potential with infinite range as the number of particles N goes to infinity under the Boltzmann-Grad scaling. More particularly, we will describe the motion of a tagged particle in a gas close to global equilibrium. The main difficulty in our context is that, due to the infinite range of the potential, a non-integrable singularity appears in the angular collision kernel, making no longer valid the single-use of Lanford's strategy. Our proof relies then on a combination of Lanford's strategy, of tools developed recently by Bodineau, Gallagher and Saint-Raymond to study the collision process, and of new duality arguments to study the additional terms associated with the long-range interaction, leading to some explicit weak estimates.

  11. Extraordinary transmission beyond the cut-off through sub- λ annular aperture arrays

    NASA Astrophysics Data System (ADS)

    Baida, Fadi I.; Poujet, Yannick; Salvi, Jérôme; Labeke, Daniel Van; Guizal, Brahim

    2009-04-01

    It was recently established that coaxial nano-aperture arrays perforated in optically thick silver films exhibit an extraordinary transmission in the visible range thanks to a guided mode. However this mode has a cut-off wavelength beyond which the transmission dramatically decreases. We propose here a cascaded structure that is shown to act as a high quality spectral filter in the visible range (finesse up to 200). It is also found that the transmission is enhanced by a factor of 150 for specific wavelengths. This kind of cascaded nano-structured metallic layers offers many promising applications in nano-photonics such as the integration of functionalities for optical signal processing. It opens up the path for the conception of a new generation of integrated components based on metallo-dielectric structures that can be easily tailored as tunable devices.

  12. Percentile curves for body fatness and cut-offs to define malnutrition in Russians

    NASA Astrophysics Data System (ADS)

    Nikolaev, D. V.; Rudnev, S. G.; Starunova, O. A.; Eryukova, T. A.; Kolesnikov, V. A.; Ponomareva, E. G.; Soboleva, N. P.; Sterlikov, S. A.

    2013-04-01

    Here, we report first results of the large-scale ongoing bioelectrical impedance body composition study in Russians. By the end of 2012, 216 out of 800 Russian Health Centres submitted raw bioimpedance data on 844,221 adults and children aged 5-80 years, representing nearly 0.6% of the Russian population, who were accessed cross-sectionally using the same type of bioimpedance meter, ABC-01 Medas. Estimates of overweight, obesity, and normal weight obesity prevalence in the general population, as well as characteristics of diagnostic sensitivity and specificity of the conventional WHO BMI-based criteria of obesity depending on age are obtained. The smoothed reference centile curves for percentage fat mass are constructed, and localized cut-offs for fatness and thinness are provided that can be used both at the individual and epidemiological levels.

  13. Viscous holographic dark energy universe with Nojiri-Odintsov cut-off

    NASA Astrophysics Data System (ADS)

    Khurshudyan, Martiros

    2016-12-01

    In this paper we consider a toy model of large scale universe, when one of the dark components is a generalized holographic DE with a Nojiri-Odintsov cut-off. On the other hand, we made another assumption concerning to the companion of considered DE model due to impossibility of exact parameterization of dark side of the large scale universe. In particular, we assume an inhomogeneous viscous dark fluid discussed in literature very actively, to be possible candidate for the companion. In addition to cosmographic analysis we discuss the results from Om and two point Om analysis and estimated present day values of statefinder parameters (r,s) and (ω^' }_{de}, ω_{de}). Moreover, validity of generalized second law of thermodynamics is studied showing that theoretical results are well consistent with observational data. Constraints on cosmological parameters are due to Planck 2015 experiments.

  14. From Newton's Law to the Linear Boltzmann Equation Without Cut-Off

    NASA Astrophysics Data System (ADS)

    Ayi, Nathalie

    2017-01-01

    We provide a rigorous derivation of the linear Boltzmann equation without cut-off starting from a system of particles interacting via a potential with infinite range as the number of particles N goes to infinity under the Boltzmann-Grad scaling. More particularly, we will describe the motion of a tagged particle in a gas close to global equilibrium. The main difficulty in our context is that, due to the infinite range of the potential, a non-integrable singularity appears in the angular collision kernel, making no longer valid the single-use of Lanford's strategy. Our proof relies then on a combination of Lanford's strategy, of tools developed recently by Bodineau, Gallagher and Saint-Raymond to study the collision process, and of new duality arguments to study the additional terms associated with the long-range interaction, leading to some explicit weak estimates.

  15. Cut-off point for WHOQOL-bref as a measure of quality of life of older adults.

    PubMed

    Silva, Patrícia Aparecida Barbosa; Soares, Sônia Maria; Santos, Joseph Fabiano Guimarães; Silva, Líliam Barbosa

    2014-06-01

    OBJECTIVE To propose a cut-off for the World Health Organization Quality of Life-Bref (WHOQOL-bref) as a predictor of quality of life in older adults.METHODS Cross-sectional study with 391 older adults registered in the Northwest Health District in Belo Horizonte, MG, Southeastern Brazil, between October 8, 2010 and May 23, 2011. The older adults' quality of life was measured using the WHOQOL-bref. The analysis was rationalized by outlining two extreme and simultaneous groups according to perceived quality of life and satisfaction with health (quality of life good/satisfactory - good or very good self-reported quality of life and being satisfied or very satisfied with health - G5; and poor/very poor quality of life - poor or very poor self-reported quality of life and feeling dissatisfied or very dissatisfied with health - G6). A Receiver-Operating Characteristic curve (ROC) was created to assess the diagnostic ability of different cut-off points of the WHOQOL-bref.RESULTS ROC curve analysis indicated a critical value 60 as the optimal cut-off point for assessing perceived quality of life and satisfaction with health. The area under the curve was 0.758, with a sensitivity of 76.8% and specificity of 63.8% for a cut-off of ≥ 60 for overall quality of life (G5) and sensitivity 95.0% and specificity of 54.4% for a cut-off of < 60 for overall quality of life (G6).CONCLUSIONS Diagnostic interpretation of the ROC curve revealed that cut-off < 60 for overall quality of life obtained excellent sensitivity and negative predictive value for tracking older adults with probable worse quality of life and dissatisfied with health.

  16. Cut-off point for WHOQOL-bref as a measure of quality of life of older adults

    PubMed Central

    Silva, Patrícia Aparecida Barbosa; Soares, Sônia Maria; Santos, Joseph Fabiano Guimarães; Silva, Líliam Barbosa

    2014-01-01

    OBJECTIVE To propose a cut-off for the World Health Organization Quality of Life-Bref (WHOQOL-bref) as a predictor of quality of life in older adults. METHODS Cross-sectional study with 391 older adults registered in the Northwest Health District in Belo Horizonte, MG, Southeastern Brazil, between October 8, 2010 and May 23, 2011. The older adults’ quality of life was measured using the WHOQOL-bref. The analysis was rationalized by outlining two extreme and simultaneous groups according to perceived quality of life and satisfaction with health (quality of life good/satisfactory – good or very good self-reported quality of life and being satisfied or very satisfied with health – G5; and poor/very poor quality of life – poor or very poor self-reported quality of life and feeling dissatisfied or very dissatisfied with health – G6). A Receiver-Operating Characteristic curve (ROC) was created to assess the diagnostic ability of different cut-off points of the WHOQOL-bref. RESULTS ROC curve analysis indicated a critical value 60 as the optimal cut-off point for assessing perceived quality of life and satisfaction with health. The area under the curve was 0.758, with a sensitivity of 76.8% and specificity of 63.8% for a cut-off of ≥ 60 for overall quality of life (G5) and sensitivity 95.0% and specificity of 54.4% for a cut-off of < 60 for overall quality of life (G6). CONCLUSIONS Diagnostic interpretation of the ROC curve revealed that cut-off < 60 for overall quality of life obtained excellent sensitivity and negative predictive value for tracking older adults with probable worse quality of life and dissatisfied with health. PMID:25119934

  17. Shear avalanches in metallic glasses under nanoindentation: Deformation units and rate dependent strain burst cut-off

    SciTech Connect

    Bian, X. L.; Wang, G.; Gao, Y. L.; Zhai, Q. J.; Chan, K. C.; Ren, J. L.

    2013-09-02

    Indented metallic glasses at the nanoscale deform via strain bursts. Conventional continuum descriptions are not appropriate for such highly stochastic, intermittent deformations. In this study, after a statistical analysis of strain bursts in five metallic glasses, the dependence of the cut-off of the strain burst size on deformation units and loading rate is established. For soft metallic glasses with smaller deformation units, cut-off of the strain burst size truncates the scale-free behavior at larger strain burst sizes. For hard metallic glasses, scale-free behavior occurs in a wide range of strain burst sizes.

  18. Definition of advanced age in HIV infection: looking for an age cut-off.

    PubMed

    Blanco, José R; Jarrín, Inmaculada; Vallejo, Manuel; Berenguer, Juan; Solera, Carmen; Rubio, Rafael; Pulido, Federico; Asensi, Victor; del Amo, Julia; Moreno, Santiago

    2012-09-01

    The age of 50 has been considered as a cut-off to discriminate older subjects within HIV-infected people according to the Centers for Disease Control and Prevention (CDC). However, the International AIDS Society (IAS) mentions 60 years of age and the Department of Health and Human Services (DHHS) makes no consideration. We aimed to establish an age cut-off that could differentiate response to highly active antiretroviral therapy (HAART) and, therefore, help to define advanced age in HIV-infected patients. CoRIS is an open, prospective, multicenter cohort of HIV adults naive to HAART at entry (January 2004 to October 2009). Survival, immunological response (IR) (CD4 increase of more than 100 cell/ml), and virological response (VR) (HIV RNA less than 50 copies/ml) were compared among 5-year age intervals at start of HAART using Cox proportional hazards models, stratified by hospital and adjusted for potential confounders. Among 5514 patients, 2726 began HAART. During follow-up, 2164 (79.4%) patients experienced an IR, 1686 (61.8%) a VR, and 54 (1.9%) died. Compared with patients aged <25 years at start of HAART, those aged 50-54, 55-59, 60-64, 65-59, and 70 or older were 32% (aHR: 0.68, 95% CI: 0.52-0.87), 29% (aHR: 0.71, 95% CI: 0.53-0.96), 34% (aHR: 0.66, 95% CI: 0.46-0.95), 39% (aHR: 0.61, 95% CI: 0.37-1.00), and 43% (aHR: 0.57, 95% CI: 0.31-1.04) less likely to experience an IR. The VR was similar across all age groups. Finally, patients aged 50-59 showed a 3-fold increase (aHR: 3.58; 95% CI: 1.07-11.99) in their risk of death compared to those aged <30 years. In HIV infection, patients aged ≥50 years have a poorer immunological response to HAART and a poorer survival. This age could be used to define medically advanced age in HIV-infected people.

  19. Definition of Advanced Age in HIV Infection: Looking for an Age Cut-Off

    PubMed Central

    Jarrín, Inmaculada; Vallejo, Manuel; Berenguer, Juan; Solera, Carmen; Rubio, Rafael; Pulido, Federico; Asensi, Victor; del Amo, Julia; Moreno, Santiago

    2012-01-01

    Abstract The age of 50 has been considered as a cut-off to discriminate older subjects within HIV-infected people according to the Centers for Disease Control and Prevention (CDC). However, the International AIDS Society (IAS) mentions 60 years of age and the Department of Health and Human Services (DHHS) makes no consideration. We aimed to establish an age cut-off that could differentiate response to highly active antiretroviral therapy (HAART) and, therefore, help to define advanced age in HIV-infected patients. CoRIS is an open, prospective, multicenter cohort of HIV adults naive to HAART at entry (January 2004 to October 2009). Survival, immunological response (IR) (CD4 increase of more than 100 cell/ml), and virological response (VR) (HIV RNA less than 50 copies/ml) were compared among 5-year age intervals at start of HAART using Cox proportional hazards models, stratified by hospital and adjusted for potential confounders. Among 5514 patients, 2726 began HAART. During follow-up, 2164 (79.4%) patients experienced an IR, 1686 (61.8%) a VR, and 54 (1.9%) died. Compared with patients aged <25 years at start of HAART, those aged 50–54, 55–59, 60–64, 65–59, and 70 or older were 32% (aHR: 0.68, 95% CI: 0.52–0.87), 29% (aHR: 0.71, 95% CI: 0.53–0.96), 34% (aHR: 0.66, 95% CI: 0.46–0.95), 39% (aHR: 0.61, 95% CI: 0.37–1.00), and 43% (aHR: 0.57, 95% CI: 0.31–1.04) less likely to experience an IR. The VR was similar across all age groups. Finally, patients aged 50–59 showed a 3-fold increase (aHR: 3.58; 95% CI: 1.07–11.99) in their risk of death compared to those aged <30 years. In HIV infection, patients aged ≥50 years have a poorer immunological response to HAART and a poorer survival. This age could be used to define medically advanced age in HIV-infected people. PMID:22607516

  20. Establishing pathological cut-offs of brain atrophy rates in multiple sclerosis

    PubMed Central

    De Stefano, Nicola; Stromillo, Maria Laura; Giorgio, Antonio; Bartolozzi, Maria Letizia; Battaglini, Marco; Baldini, Mariella; Amato, Maria Pia; Sormani, Maria Pia

    2016-01-01

    Objective To assess whether it is feasible to establish specific cut-off values able to discriminate ‘physiological’ or ‘pathological’ brain volume rates in patients with multiple sclerosis (MS). Methods The study was based on the analysis of longitudinal MRI data sets of patients with MS (n=206, 87% relapsing–remitting, 7% secondary progressive and 6% primary progressive) and healthy controls (HC; n=35). Brain atrophy rates were computed over a mean follow-up of 7.5 years (range 1–12) for patients with MS and 6.3 years (range 1–12.5) for HC with the SIENA software and expressed as annualised per cent brain volume change (PBVC/y). A weighted (on the follow-up length) receiver operating characteristic analysis and the area under the curve (AUC) were used for statistics. Results The weighted PBVC/y was −0.51±0.27% in patients with MS and −0.27±0.15% in HC (p<0.0001). There was a significant age-related difference in PBVC/y between HC older and younger than 35 years of age (p=0.02), but not in patients with MS (p=0.8). The cut-off of PBVC/y, as measured by SIENA that could maximise the accuracy in discriminating patients with MS from HC, was −0.37%, with 67% sensitivity and 80% specificity. According to the observed distribution, values of PBVC/y as measured by SIENA that could define a pathological range were above −0.52% with 95% specificity, above −0.46% with 90% specificity and above −0.40% with 80% specificity. Conclusions Our evidence-based criteria provide values able to discriminate the presence or absence of ‘pathological’ brain volume loss in MS with high specificity. Such results could be of great value in a clinical setting, particularly in assessing treatment efficacy in MS. PMID:25904813

  1. Intense, Narrow-band THz Emission from a Current Source Immersed in Cut-off of Plasma-like Media

    NASA Astrophysics Data System (ADS)

    Hur, Min Sup; Ersfeld, Bernhard; Noble, Adam; Suk, Hyyong; Jaroszynski, Dino

    2016-10-01

    Recently we found an interesting behavior of the electromagnetic radiation emerging from cut-off condition of a plasma-like medium, when it is driven by a current source. Differently from conventional total reflection of the incident wave at the cut-off, we found a spatially diffusing and temporally growing electromagnetic field from the current source. Direct result of such diffusion-growth is the selectively enhanced emission (SEE) at the cut-off frequency from a generally broadband current oscillation. We demonstrate examples demonstrating the SEE. One is the two-color-driven THz emission from field ionization of the gas slab located in a tapered waveguide. The emission propagating through the waveguide exhibits a significantly enhanced spectral density at the cut-off frequency. The other example is the THz emission from a magnetized plasma driven by two colliding ultra-short laser pulses. Since a very narrow-band emission can be selectively enhanced from a broadband radiation source, the SEE concept can be used for conversion of a general broadband THz source to a narrow-band one by locating it in a meta-structure such as the waveguide or a plasma-like medium. We discuss other possible systems to which SEE can be applied.

  2. On determining the most appropriate test cut-off value: the case of tests with continuous results

    PubMed Central

    Habibzadeh, Parham; Yadollahie, Mahboobeh

    2016-01-01

    There are several criteria for determination of the most appropriate cut-off value in a diagnostic test with continuous results. Mostly based on receiver operating characteristic (ROC) analysis, there are various methods to determine the test cut-off value. The most common criteria are the point on ROC curve where the sensitivity and specificity of the test are equal; the point on the curve with minimum distance from the left-upper corner of the unit square; and the point where the Youden’s index is maximum. There are also methods mainly based on Bayesian decision analysis. Herein, we show that a proposed method that maximizes the weighted number needed to misdiagnose, an index of diagnostic test effectiveness we previously proposed, is the most appropriate technique compared to the aforementioned ones. For determination of the cut-off value, we need to know the pretest probability of the disease of interest as well as the costs incurred by misdiagnosis. This means that even for a certain diagnostic test, the cut-off value is not universal and should be determined for each region and for each disease condition. PMID:27812299

  3. 26 CFR 1.585-7 - Elective cut-off method of changing from the reserve method of section 585.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... loans. (d) Effect of disposing of loans—(1) In general. Except as provided in paragraphs (d)(2) and (d... into the shoes of the transferor in the section 381(a) transaction with respect to using the cut-off...) received in the transaction, the acquiror does not step into the shoes of the transferor with respect...

  4. 26 CFR 1.585-7 - Elective cut-off method of changing from the reserve method of section 585.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... loans. (d) Effect of disposing of loans—(1) In general. Except as provided in paragraphs (d)(2) and (d... into the shoes of the transferor in the section 381(a) transaction with respect to using the cut-off...) received in the transaction, the acquiror does not step into the shoes of the transferor with respect...

  5. 26 CFR 1.585-7 - Elective cut-off method of changing from the reserve method of section 585.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... loans. (d) Effect of disposing of loans—(1) In general. Except as provided in paragraphs (d)(2) and (d... into the shoes of the transferor in the section 381(a) transaction with respect to using the cut-off...) received in the transaction, the acquiror does not step into the shoes of the transferor with respect...

  6. 26 CFR 1.585-7 - Elective cut-off method of changing from the reserve method of section 585.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... loans. (d) Effect of disposing of loans—(1) In general. Except as provided in paragraphs (d)(2) and (d... into the shoes of the transferor in the section 381(a) transaction with respect to using the cut-off...) received in the transaction, the acquiror does not step into the shoes of the transferor with respect...

  7. 26 CFR 1.585-7 - Elective cut-off method of changing from the reserve method of section 585.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... loans. (d) Effect of disposing of loans—(1) In general. Except as provided in paragraphs (d)(2) and (d... into the shoes of the transferor in the section 381(a) transaction with respect to using the cut-off...) received in the transaction, the acquiror does not step into the shoes of the transferor with respect...

  8. Dynamic monitoring of menopause hormone therapy and defining the cut-off value of endometrial thickness during uterine bleeding

    PubMed Central

    Sheng, Qiu; Yang, Jun; Zhao, Qiaoling; Li, Fen

    2016-01-01

    Abstract The aim of this study was to evaluate the effects of low-dose tibolone therapy on ovarian area, uterine volume and endometrial thickness, and define the cut-off value of endometrial thickness for curettage during uterine bleeding. We followed 619 postmenopausal women, aged 40-60 years, for two years. There were 301 subjects in the low-dose tibolone treatment group and 318 subjects in the control group. The ovarian area, uterine volume and endometrial thickness in all participants were measured by transvaginal ultrasound prior to, one and two years post enrollment, respectively. Endometrial specimens were collected from all subjects with abnormal uterine bleeding during the follow-up period. We found that the uterine volume in the treatment group was greater than that in the control group, and the difference was significant (P<0.05), but there were no significant differences in ovarian area and endometrial thickness between the two groups (P>0.05). When the cut-off value for endometrial thickness was 7.35 mm, the sensitivity and specificity were 100% and 79.07%, respectively, and 85.71% and 93.02% when 7.55 mm was set as the cut-off during tibolone therapy. The results indicate that low-dose tibolone therapy may postpone uterine atrophy and the cut-off value of endometrial thickness may be appropriately adjusted for curettage. PMID:27533929

  9. Extended characterization of a new class of membranes for blood purification: the high cut-off membranes.

    PubMed

    Boschetti-de-Fierro, Adriana; Voigt, Manuel; Storr, Markus; Krause, Bernd

    2013-07-01

    High cut-off membranes are a new class of blood purification membranes whose particular characteristics present challenges for commonly-used characterization methods. Dextran sieving curves for representative blood purification membranes of the high-flux and high cut-off types were measured and compared to curves for the glomerular filtration barrier (GFB). The performance was also determined after blood exposure for the most permeable synthetic membranes. High cut-off membranes were observed to be more open than the GFB before blood exposure, but become tighter and more selective after the exposure, keeping the permeation for low and middle molecules while restraining the filtration of large species. Based on dextran sieving experiments for a variety of commercially available blood purification membranes, we present a novel method for classifying blood purification membranes. By using a well-established technique and introducing a new characteristic parameter for the sieving curve--the molecular weight retention onset (MWRO)--a graph of molecular weight cut-off versus molecular weight retention onset provides the landscape of dialysis membrane types. This meaningful representation is based on only one in vitro method, and allows the membrane classification by indirectly considering two structural parameters: pore size and pore size distribution. In this way, the families of low-flux, high-flux, protein leaking, and high cut-off membranes are clearly differentiated. The differentiation allows for the definition of MWCO/MWRO regions for the different types, so that further classification of newly developed membranes can be easily achieved.

  10. Estimate of a predictive cut-off value for serum 25-hydroxyvitamin D reflecting abdominal obesity in Korean adolescents.

    PubMed

    Nam, Ga Eun; Kim, Do Hoon; Cho, Kyung Hwan; Park, Yong Gyu; Han, Kyung Do; Choi, Youn Seon; Kim, Seon Mee; Ko, Byung Joon; Kim, Yang Hyun; Lee, Kyung Shik

    2012-06-01

    Vitamin D deficiency is a serious global issue. Although the serum 25-hydroxyvitamin D [25(OH)D] test is generally the most accurate way to assess vitamin D levels, the optimal range of 25(OH)D has yet to be established. Moreover, the optimal level may vary according to race, region, and age. Suboptimal vitamin D status is associated with obesity and metabolic syndrome, which are the major risk factors for cardiovascular disorders; however, these relationships in children and adolescents have yet to be clearly determined. Therefore, we identified the best predictive cut-off value for reflecting abdominal obesity and, based on this value, we investigated the relationship between suboptimal 25(OH)D status and the risk for having abdominal obesity, being overweight or obese, and having metabolic syndrome in Korean adolescents. We performed a cross-sectional analysis of 713 Korean adolescents, between 12-19 years of age, and used data collected from the 2008 Korea National Health and Nutrition Examination Survey (KNHANES). Receiver operation characteristic curve analysis was used to identify the cut-off value that reflected abdominal obesity. The cut-off value of serum 25(OH)D that reflected abdominal obesity in Korean adolescents was 17.6 ng/mL. After making adjustments for gender, age, and regular physical exercise, the group that had lower levels of serum 25(OH)D compared to the cut-off value had a significantly higher risk for abdominal obesity, obesity, and metabolic syndrome than the group with 25(OH)D levels higher than the cut-off value. Suboptimal vitamin D status based on this value is associated with increased risk for abdominal obesity, obesity, and metabolic syndrome among Korean adolescents.

  11. Susceptibility profile and epidemiological cut-off values of Cryptococcus neoformans species complex from Argentina.

    PubMed

    Córdoba, Susana; Isla, Maria G; Szusz, Wanda; Vivot, Walter; Altamirano, Rodrigo; Davel, Graciela

    2016-06-01

    Epidemiological cut-off values (ECVs) based on minimal inhibitory concentration (MIC) distribution have been recently proposed for some antifungal drug/Cryptococcus neoformans combinations. However, these ECVs vary according to the species studied, being serotypes and the geographical origin of strains, variables to be considered. The aims were to define the wild-type (WT) population of the C. neoformans species complex (C. neoformans) isolated from patients living in Argentina, and to propose ECVs for six antifungal drugs. A total of 707 unique C. neoformans isolates obtained from HIV patients suffering cryptococcal meningitis were studied. The MIC of amphotericin B, flucytosine, fluconazole, itraconazole, voriconazole and posaconazole was determined according to the EDef 7.2 (EUCAST) reference document. The MIC distribution, MIC50 , MIC90 and ECV for each of these drugs were calculated. The highest ECV, which included ≥95% of the WT population modelled, was observed for flucytosine and fluconazole (32 μg ml(-1) each). For amphotericin B, itraconazole, voriconazole and posaconazole, the ECVs were: 0.5, 0.5, 0.5 and 0.06 μg ml(-1) respectively. The ECVs determined in this study may aid in identifying the C. neoformans strains circulating in Argentina with decreased susceptibility to the antifungal drugs tested.

  12. Accuracy of Cameriere's cut-off value for third molar in assessing 18 years of age.

    PubMed

    De Luca, S; Biagi, R; Begnoni, G; Farronato, G; Cingolani, M; Merelli, V; Ferrante, L; Cameriere, R

    2014-02-01

    Due to increasingly numerous international migrations, estimating the age of unaccompanied minors is becoming of enormous significance for forensic professionals who are required to deliver expert opinions. The third molar tooth is one of the few anatomical sites available for estimating the age of individuals in late adolescence. This study verifies the accuracy of Cameriere's cut-off value of the third molar index (I3M) in assessing 18 years of age. For this purpose, a sample of orthopantomographs (OPTs) of 397 living subjects aged between 13 and 22 years (192 female and 205 male) was analyzed. Age distribution gradually decreases as I3M increases in both males and females. The results show that the sensitivity of the test was 86.6%, with a 95% confidence interval of (80.8%, 91.1%), and its specificity was 95.7%, with a 95% confidence interval of (92.1%, 98%). The proportion of correctly classified individuals was 91.4%. Estimated post-test probability, p was 95.6%, with a 95% confidence interval of (92%, 98%). Hence, the probability that a subject positive on the test (i.e., I3M<0.08) was 18 years of age or older was 95.6%.

  13. Sloshing in the Liquid Hydrogen and Liquid Oxygen Propellant Tanks After Main Engine Cut Off

    NASA Technical Reports Server (NTRS)

    Kim, Sura; West, Jeff

    2011-01-01

    NASA Marshall Space Flight Center is designing and developing the Main Propulsion System (MPS) for Ares launch vehicles. Propellant sloshing in the liquid hydrogen (LH2) and liquid oxygen (LO2) propellant tanks after Main Engine Cut Off (MECO) was modeled using the Volume of Fluid (VOF) module of the computational fluid dynamics code, CFD-ACE+. The present simulation shows that there is substantial sloshing side forces acting on the LH2 tank during the deceleration of the vehicle after MECO. The LH2 tank features a side wall drain pipe. The side loads result from the residual propellant mass motion in the LH2 tank which is initiated by the stop of flow into the drain pipe at MECO. The simulations show that radial force on the LH2 tank wall is less than 50 lbf and the radial moment calculated based up through the center of gravity of the vehicle is predicted to be as high as 300 lbf-ft. The LO2 tank features a bottom dome drain system and is equipped with sloshing baffles. The remaining LO2 in the tank slowly forms a liquid column along the centerline of tank under the zero gravity environments. The radial force on the LO2 tank wall is predicted to be less than 100 lbf. The radial moment calculated based on the center of gravity of the vehicle is predicted as high as 4500 lbf-ft just before MECO and dropped down to near zero after propellant draining stopped completely.

  14. Mechanically robust 39 GHz cut-off frequency graphene field effect transistors on flexible substrates.

    PubMed

    Wei, Wei; Pallecchi, Emiliano; Haque, Samiul; Borini, Stefano; Avramovic, Vanessa; Centeno, Alba; Amaia, Zurutuza; Happy, Henri

    2016-08-07

    Graphene has been regarded as a promising candidate channel material for flexible devices operating at radio-frequency (RF). In this work we fabricated and fully characterized double bottom-gate graphene field effect transistors on flexible polymer substrates for high frequency applications. We report a record high as-measured current gain cut-off frequency (ft) of 39 GHz. The corresponding maximum oscillation frequency (fmax) is 13.5 GHz. These state of the art high frequency performances are stable against bending, with a typical variation of around 10%, for a bending radius of up to 12 mm. To demonstrate the reliability of our devices, we performed a fatigue stress test for RF-GFETs which were dynamically bend tested 1000 times at 1 Hz. The devices are mechanically robust, and performances are stable with typical variations of 15%. Finally we investigate thermal dissipation, which is a critical parameter for flexible electronics. We show that at the optimum polarization the normalized power dissipated by the GFETs is about 0.35 mW μm(-2) and that the substrate temperature is around 200 degree centigrade. At a higher power, irreversible degradations of the performances are observed. Our study on state of the art flexible GFETs demonstrates mechanical robustness and stability upon heating, two important elements to assess the potential of GFETs for flexible electronics.

  15. Azole susceptibility of Malassezia pachydermatis and Malassezia furfur and tentative epidemiological cut-off values.

    PubMed

    Cafarchia, Claudia; Iatta, Roberta; Immediato, Davide; Puttilli, Maria Rita; Otranto, Domenico

    2015-09-01

    This study aims to determine the minimal inhibitory concentration (MIC) distribution and the epidemiological cut-off values (ECVs) of Malassezia pachydermatis and Malassezia furfur isolates for fluconazole (FLZ), itraconazole (ITZ), posaconazole (POS), and voriconazole (VOR). A total of 62 M. pachydermatis strains from dogs with dermatitis and 78 M. furfur strains from humans with bloodstream infections (BSI) were tested by a modified broth microdilution Clinical and Laboratory Standards Institute (CLSI) method. ITZ and POS displayed lower MICs than VOR and FLZ, regardless of the Malassezia species. The MIC data for azoles of M. pachydermatis were four two-fold dilutions lower than those of M. furfur. Based on the ECVs, about 94% of Malassezia strains might be categorized within susceptible population for all azoles, except for FLZ, and azole cross-resistance was detected in association with FLZ in M. pachydermatis but not in M. furfur.The study proposes, for the first time, tentative azole ECVs for M. pachydermatis and M. furfur for monitoring the emergence of isolates with decreased susceptibilities and shows that the azole MIC distribution varied according to the Malassezia species tested, thus suggesting the usefulness of determining the susceptibility profile for effective treatment of each species.

  16. The Objective Borderline Method (OBM): A Probability-Based Model for Setting up an Objective Pass/Fail Cut-Off Score in Medical Programme Assessments

    ERIC Educational Resources Information Center

    Shulruf, Boaz; Turner, Rolf; Poole, Phillippa; Wilkinson, Tim

    2013-01-01

    The decision to pass or fail a medical student is a "high stakes" one. The aim of this study is to introduce and demonstrate the feasibility and practicality of a new objective standard-setting method for determining the pass/fail cut-off score from borderline grades. Three methods for setting up pass/fail cut-off scores were compared: the…

  17. Mechanically robust 39 GHz cut-off frequency graphene field effect transistors on flexible substrates

    NASA Astrophysics Data System (ADS)

    Wei, Wei; Pallecchi, Emiliano; Haque, Samiul; Borini, Stefano; Avramovic, Vanessa; Centeno, Alba; Amaia, Zurutuza; Happy, Henri

    2016-07-01

    Graphene has been regarded as a promising candidate channel material for flexible devices operating at radio-frequency (RF). In this work we fabricated and fully characterized double bottom-gate graphene field effect transistors on flexible polymer substrates for high frequency applications. We report a record high as-measured current gain cut-off frequency (ft) of 39 GHz. The corresponding maximum oscillation frequency (fmax) is 13.5 GHz. These state of the art high frequency performances are stable against bending, with a typical variation of around 10%, for a bending radius of up to 12 mm. To demonstrate the reliability of our devices, we performed a fatigue stress test for RF-GFETs which were dynamically bend tested 1000 times at 1 Hz. The devices are mechanically robust, and performances are stable with typical variations of 15%. Finally we investigate thermal dissipation, which is a critical parameter for flexible electronics. We show that at the optimum polarization the normalized power dissipated by the GFETs is about 0.35 mW μm-2 and that the substrate temperature is around 200 degree centigrade. At a higher power, irreversible degradations of the performances are observed. Our study on state of the art flexible GFETs demonstrates mechanical robustness and stability upon heating, two important elements to assess the potential of GFETs for flexible electronics.Graphene has been regarded as a promising candidate channel material for flexible devices operating at radio-frequency (RF). In this work we fabricated and fully characterized double bottom-gate graphene field effect transistors on flexible polymer substrates for high frequency applications. We report a record high as-measured current gain cut-off frequency (ft) of 39 GHz. The corresponding maximum oscillation frequency (fmax) is 13.5 GHz. These state of the art high frequency performances are stable against bending, with a typical variation of around 10%, for a bending radius of up to 12 mm. To

  18. Galactomannan Assay and Invasive Pulmonary Aspergillosis - Comparison of the Test Performance at an in-house and the Kit Cut-off

    PubMed Central

    Menon, Nikhilesh Ravikumar; Sudharma, Arun Ramachandran; Jairaj, Vinutha; Mathew, Joshila

    2016-01-01

    Introduction Invasive Pulmonary Aspergillosis (IPA) is an important opportunistic infection with a high degree of mortality and morbidity. Galactomannan assay (GM assay) is found to be useful for diagnosis of IPA in patients with neutropenia. However the utility of this assay has not been evaluated in a mixed patient population with other co-morbid conditions. Though a kit cut-off of 0.5 has been recommended for the diagnosis of IPA, studies have reported a higher sensitivity with cut-offs more than 0.5. Aim To establish an in-house cut-off and compare its utility with the kit cut-off to diagnose and categorize IPA as proven, probable and possible in patients with varied underlying risk factors. Materials and Methods This observational study was done in St John’s Medical College, Bangalore, Karnataka, India from January 2013-December 2014. GM assay was performed on 25 each of healthy controls and clinically diagnosed cases of IPA. The in-house cut-off was calculated by plotting the Receiver Operating Characteristic Curve (ROC). Results The in-house cut-off was calculated to be 0.52. Using this and the kit cut-off (0.5), the Sensitivity, Specificity, Positive Predictive Value (PPV) and the Negative Predictive Value (NPV) were found to be 75%, 79%, 76%, 82% and 79%, 71%, 77%, 82% respectively. Diabetes mellitus was found to be associated with more than 50% of the patients. Conclusion The established in house cut-off using healthy controls and patients with clinical diagnosis of IPA was not significantly different from that of the kit cut-off. Using either of these cut-offs, we could re-categorize two of the possible IPA cases in the probable group. This study helped to understand the clinical utility of this assay even in a mixed patient population with multiple co-morbidities. PMID:27656435

  19. Sloshing in Liquid Hydrogen and LOX Propellant Tanks After Main Engine Cut-off

    NASA Technical Reports Server (NTRS)

    Kim, Sura

    2011-01-01

    NASA Marshall Space Flight Center is designing and developing the Main Propulsion System (MPS) for Ares launch vehicles. The objective of this study is to calculate the sloshing forces and moments in the LH2 and LO2 propellant tanks using a CFD/VOF analysis under realistic flight conditions. Propellant sloshing in the liquid hydrogen (LH2) and the liquid oxygen (LO2) propellant tanks after Main Engine Cut Off (MECO) was modeled using the Volume of Fluid (VOF) module of the computational fluid dynamics code, CFD-ACE+. The present simulation shows that there are substantial sloshing side forces acting on the LH2 tank during the deceleration of the vehicle after MECO. The LH2 tank features a side wall drain pipe. The side loads result from the residual propellant mass motion in the LH2 tank which is initiated by the stop of flow into the drain pipe at MECO. The simulations show that radial force on the LH2 tank wall is less than 50 lbf and the radial moment calculated based up the center of gravity of the vehicle is predicted to be as high as 300 lbf-ft. The LO2 tank features a bottom dome drain system and is equipped with sloshing baffles. The remaining LO2 in the tank slowly forms a liquid column along the centerline of tank under the zero gravity environments. The radial force on the LO2 tank wall is predicted less than 100 lbf. The radial moment calculated based on the center of gravity of the vehicle is predicted as high as 4500 lbf-ft just before MECO and dropped down to near zero after propellant draining stopped completely.

  20. Metacognitive impairments in schizophrenia are arrested at extreme levels of psychopathy: The cut-off effect.

    PubMed

    Abu-Akel, Ahmad; Heinke, Dietmar; Gillespie, Steven M; Mitchell, Ian J; Bo, Sune

    2015-11-01

    Psychopathy and metacognitive difficulties have been associated with the occurrence of violence in schizophrenia. However, evidence suggests that nonschizophrenic psychopaths match or even outperform healthy controls on tests of metacognition. We hypothesize that the metacognitive difficulties associated with schizophrenia may be ameliorated by comorbid psychopathy. To this end, metacognition (using the Metacognition Assessment Scale-Abbreviated [MAS-A]) and psychopathy (using the Hare Psychopathy Checklist-Revised [PCL-R]) are assessed in 79 patients with schizophrenia with a history of criminal offending. Piecewise regression reveals that the association between metacognition and psychopathy changes from a negative to a positive association at a breakpoint corresponding to a score of 24 on the PCL-R. This score is within the range of the cut-off point used for the diagnosis of psychopathy in Europe, which corresponds to a score of 26 on the PCL-R. The patients scoring above 24 on the PCL-R demonstrated better overall metacognitive abilities, suggesting that these patients constitute a specific group in which schizophrenia has an attenuated impairing effect on metacognition. However, this effect was absent for the Mastery subscale of the MAS-A, which refers to the ability to use one's own mental states to solve social and psychological dilemmas. Our results suggest that the relative preservation of metacognitive abilities in schizophrenic patients with extreme levels of psychopathy may contribute to their offending behavior as it may enable them to understand how to manipulate and extort their victims. However, enhancing the Mastery domain of metacognition in these patients may attenuate this offending behavior.

  1. [Receiver operating characteristic analysis and the cost--benefit analysis in determination of the optimal cut-off point].

    PubMed

    Vránová, J; Horák, J; Krátká, K; Hendrichová, M; Kovaírková, K

    2009-01-01

    An overview of the use of Receiver Operating Characteristic (ROC) analysis within medicine is provided. A survey of the theory behind the analysis is offered together with a presentation on how to create a ROC curve and how to use Cost--Benefit analysis to determine the optimal cut-off point or threshold. The use of ROC analysis is exemplified in the "Cost--Benefit analysis" section of the paper. In these examples, it can be seen that the determination of the optimal cut-off point is mainly influenced by the prevalence and the severity of the disease, by the risks and adverse events of treatment or the diagnostic testing, by the overall costs of treating true and false positives (TP and FP), and by the risk of deficient or non-treatment of false negative (FN) cases.

  2. Cut-off analysis of 19-cell Yb-doped double-cladding rod-type photonic crystal fibers.

    PubMed

    Poli, F; Coscelli, E; Alkeskjold, T T; Passaro, D; Cucinotta, A; Leick, L; Broeng, J; Selleri, S

    2011-05-09

    Yb-doped double-cladding large mode area rod-type photonic crystal fibers are a key component for power scaling in fiber laser systems. Recently, designs with 19-cell core defect, that is with 19 missing air-holes in the center of the photonic crystal cladding, have been proposed, with reported core diameter up to 100 μm. In this paper an analysis of the cut-off wavelength of the first high-order mode in such low-NA fibers is reported, accounting for different approaches for the definition of the cladding effective index. Results have shown that taking into account the finite fiber cross-section and considering the first cladding mode of the actual fiber is mandatory to obtain a correct estimate of the cut-off wavelength.

  3. Gestational Age-specific Cut-off Values Are Needed for Diagnosis of Subclinical Hypothyroidism in Early Pregnancy.

    PubMed

    Kim, Hye Sung; Kim, Byoung Jae; Oh, Sohee; Lee, Da Young; Hwang, Kyu Ri; Jeon, Hye Won; Lee, Seung Mi

    2015-09-01

    During the first trimester of pregnancy, thyroid-stimulating hormone (TSH) >2.5 mIU/L has been suggested as the universal criterion for subclinical hypothyroidism. However, TSH levels change continuously during pregnancy, even in the first trimester. Therefore the use of a fixed cut-off value for TSH may result in a different diagnosis rate of subclinical hypothyroidism according to gestational age. The objective of this study was to obtain the normal reference range of TSH during the first trimester in Korean gravida and to determine the diagnosis rate of subclinical hypothyroidism using the fixed cut-off value (TSH >2.5 mIU/L). The study population consisted of pregnant women who were measured for TSH during the first trimester of pregnancy (n=492) and nonpregnant women (n=984). Median concentration of TSH in pregnant women was lower than in non-pregnant women. There was a continuous decrease of median TSH concentration during the first trimester of pregnancy (median TSH concentration: 1.82 mIU/L for 3+0 to 6+6 weeks; 1.53 mIU/L for 7+0 to 7+6 weeks; and 1.05 mIU/L for 8+0 to 13+6 weeks). Using the fixed cut-off value of TSH >2.5 mIU/L, the diagnosis rate of subclinical hypothyroidism decreased significantly according to the gestational age (GA) at TSH (25% in 3+0 to 6+6 weeks, 13% in 7+0 to 7+6 weeks, and 9% for 8+0 to 13+6 weeks, P<0.001), whereas the diagnosis rate was 5% in all GA with the use of a GA-specific cut-off value (P=0.995). Therefore, GA-specific criteria might be more appropriate for the diagnosis of subclinical hypothyroidism.

  4. Cut-Off Value for Pain Sensitivity Questionnaire in Predicting Surgical Success in Patients with Lumbar Disc Herniation

    PubMed Central

    Azimi, Parisa; Benzel, Edward C.

    2016-01-01

    Various factors related to predict surgical success were studied; however, a standard cut-off point for the Pain Sensitivity Questionnaire (PSQ) measure has not yet been established for a favorable surgical outcome for lumbar disc herniation (LDH). This study was to find the optimal cut-off point on the PSQ to distinguish surgical success in patients with LDH. A total of 154 patients with LDH consecutively referred to our clinic were enrolled into this prospective study between February 2011 and January 2014. All participants completed the PSQ. Patients completed the Oswestry Disability Index (ODI) score before surgery, and at 2 years after surgery. Surgical success was defined as a 13-point improvement from the baseline ODI scores. The cut-off value for PSQ was determined by the receiver-operating characteristic curve (ROC). The mean age of patients was 49.3±9.6 years, and there were 80 women. The mean time for follow-up assessment was 31±5 months (range 24–35). Post-surgical success was 79.9% (n = 123) at 2 years follow up. The mean score for the total PSQ, PSQ-minor, and PSQ-moderate were 6.0 (SD = 1.6), 5.4 (SD = 1.9) and 6.5 (SD = 1.7), respectively. Total PSQ score was also significantly correlated with the total scores of the ODI. The optimal total PSQ cut-off point was determined as > 5.2 to predict surgical success in LDH patients, with 80.0% sensitivity and 75.6% specificity (AUC-0.814, 95% CI 0.703–0.926). This study showed that the PSQ could be considered a parameter for predicting surgical success in patients with LDH, and can be useful in clinical practice. PMID:27494617

  5. Some Factors Affecting the Reproducibility of Penetration and the Cut-Off of Oil Sprays for Fuel-injection Engines

    NASA Technical Reports Server (NTRS)

    Beardsley, E G

    1928-01-01

    This investigation was undertaken at the Langley Memorial Aeronautical Laboratory in connection with a general research on fuel-injection for aircraft. The purpose of the investigation was to determine the factors controlling the reproducibility of spray penetration and secondary discharges after cut-off. The development of single sprays from automatic injection valves was recorded by means of special high-speed photographic apparatus capable of taking 25 consecutive pictures of the moving spray at a rate of 4,000 per second. The effect of two types of injection valves, injection-valve tube length, initial pressure in the injection-valve tube, speed of the injection control mechanism, and time of spray cut-off, on the reproducibility of spray penetration, and on secondary discharges were investigated. It was found that neither type of injection valve materially affected spray reproducibility. The initial pressure in the injection-valve tube controlled the reproducibility of spray penetrations. An increase in the initial pressure or in the length of the injection-valve tube slightly increased the spray penetration within the limits of this investigation. The speed of the injection-control mechanism did not affect the penetration. Analysis of the results indicates that secondary discharges were caused in this apparatus by pressure waves initiated by the rapid opening of the cut-off valve. The secondary discharges were eliminated in this investigation by increasing the length of the injection-valve tube. (author)

  6. Cut-off values of blood mercury concentration in relation to increased body mass index and waist circumference in Koreans.

    PubMed

    Bae, Suhyun; Park, Soo-Jung; Yeum, Kyung-Jin; Choi, Beomhee; Kim, Young-Sang; Joo, Nam-Seok

    2016-04-01

    Blood mercury (methyl-mercury) from environmental exposure may be related to inflammation in our body. We investigated the cut-off values of blood mercury concentration in relation to increased body mass index (BMI) and waist circumference. On the basis of data obtained from the Korea National Health and Nutrition Examination Survey (KNHANES, 2008-2012), 11,159 subjects (5543 males and 5616 females) were analyzed cross-sectionally. Partial correlation, linear regression, and analysis of covariance (according to the mercury quartile) tests were performed to evaluate the relationship between blood mercury and BMI or waist circumference. In addition, we determined the cut-off values of blood mercury concentration in relation to increased BMI and waist circumference in both genders. Mean values of blood mercury concentration were 5.07 ± 0.07 μg/L in males and 3.59 ± 0.04 μg/L in females. After log transformation of blood mercury, significant (p < 0.001) correlation was found between blood mercury concentration and BMI or waist circumference. BMI and waist circumference showed a significant and gradual increase as mercury quartile increased in both genders. Blood mercury concentration was weakly but significantly (p < 0.001) associated with BMI and waist circumference. Cut-off values of blood mercury concentration correlated with increased BMI and waist circumference were around 3.95 μg/L in males and 3.40 μg/L in females.

  7. Ozone transport during a cut-off low event studied in the frame of the TOASTE program

    NASA Technical Reports Server (NTRS)

    Ancellet, G.; Beekmann, M.; Papayannis, A.; Megie, G.

    1994-01-01

    A study of ozone transfer to the troposphere has been performed during two phases of the evolution of a cut-off low using both ozone vertical profiles and objective analysis of the ECMWF to compute potential vorticity distributions and air mass trajectories. Ozone profiles were measured by a ground based lidar system at the Observatoire de Haute Provence (OHP, 43 deg 55 N, 5 deg 42 E). A stratospheric ozone transport into the troposphere has been observed during a tropopause fold which occurred at the beginning of the cut-off low formation and during the erosion phase of the cut-off low. From the estimate of the maximum ozone content transferred to the troposphere, both mechanisms have the same order of magnitude of influence on the ozone flux to the troposphere. On a time scale of a few days, the correlation is very good between the potential vorticity and the ozone time evolution in the vicinity of the upper level frontal system.

  8. Interstellar flow longitude from pickup ion cut-off observations at 1 AU with STEREO and ACE

    NASA Astrophysics Data System (ADS)

    Möbius, E.; Lee, M. A.; Gloeckler, G.; Drews, C.; Keilbach, D.

    2016-11-01

    A precision determination of the interstellar neutral (ISN) flow direction is important in several ways. As a cardinal axis of the heliosphere it has strong leverage on the plane subtended by the ISN velocity and interstellar magnetic field vector, which controls the shape of the heliosphere and its interaction with the interstellar medium. Continuing observations of the ISN flow through the heliosphere for several decades allow the search for potential temporal variations of the ISN flow and comparison with astronomical observations. Recent efforts to obtain a consistent ISN vector and temperature with Ulysses and IBEX neutral gas observations point to remaining uncertainties and potential systematic effects. In particular, IBEX measurements provide a very precise relation between ISN flow longitude and speed via the hyperbolic trajectory equation, but they contain larger uncertainties along the parameter tube defined by this relation. The pickup ion (PUI) cut-off variation with ecliptic longitude at 1 AU can provide a complementary determination of the ISN flow longitude with high precision. We compare STEREO PLASTIC and ACE SWICS observations with a simple analytical model of the cut-off. We perform a Pearson correlation analysis of the cut-off as a function of ecliptic longitude with its mirrored function and obtain the symmetry axis with a statistical uncertainty <0.1°. Here we test variations of this value due to Poisson fluctuations in the original data with simulations and due to systematic effects with multi year and location ACE SWICS and STEREO PLASTIC samples.

  9. Insulin sensitivity indices: a proposal of cut-off points for simple identification of insulin-resistant subjects.

    PubMed

    Radikova, Z; Koska, J; Huckova, M; Ksinantova, L; Imrich, R; Vigas, M; Trnovec, T; Langer, P; Sebokova, E; Klimes, I

    2006-05-01

    Demanding measurement of insulin sensitivity using clamp methods does not simplify the identification of insulin resistant subjects in the general population. Other approaches such as fasting- or oral glucose tolerance test-derived insulin sensitivity indices were proposed and validated with the euglycemic clamp. Nevertheless, a lack of reference values for these indices prevents their wider use in epidemiological studies and clinical practice. The aim of our study was therefore to define the cut-off points of insulin resistance indices as well as the ranges of the most frequently obtained values for selected indices. A standard 75 g oral glucose tolerance test was carried out in 1156 subjects from a Caucasian rural population with no previous evidence of diabetes or other dysglycemias. Insulin resistance/sensitivity indices (HOMA-IR, HOMA-IR2, ISI Cederholm, and ISI Matsuda) were calculated. The 75th percentile value as the cut-off point to define IR corresponded with a HOMA-IR of 2.29, a HOMA-IR2 of 1.21, a 25th percentile for ISI Cederholm, and ISI Matsuda of 57 and 5.0, respectively. For the first time, the cut-off points for selected indices and their most frequently obtained values were established for groups of subjects as defined by glucose homeostasis and BMI. Thus, insulin-resistant subjects can be identified using this simple approach.

  10. Amphetamines and 3,4-methylendioxymetamphetamine (MDMA): evaluation of KIMS (kinetic interaction of microparticles in solution) assay at two cut-off levels.

    PubMed

    Marchioro, Lucio; Bassetto, Flavia; Dall'Olio, Giuliano; Tedeschi, Luciano; Castagna, Franca; Plebani, Mario

    2004-05-01

    Two screening methods for the assay of amphetamines and their derivatives have been applied to the same analytical instrument for their evaluation. In addition to an assay at a cut-off of 1000 microg/l, a new specific reagent was evaluated for an ultra-sensitive assay of amphetamines and 3,4-methylendioxymetamphetamine with a cut-off of 300 microg/l. The assay confirmation was performed using high-performance liquid chromatography and gas chromatography/ mass spectrometry techniques. The results were positive for both screening methods, confirming the efficacy of two simultaneous methods with different cut-off levels.

  11. Geomagnetism applications

    USGS Publications Warehouse

    Campbell, Wallace H.

    1995-01-01

    The social uses of geomagnetism include the physics of the space environment, satellite damage, pipeline corrosion, electric power-grid failure, communication interference, global positioning disruption, mineral-resource detection, interpretation of the Earth's formation and structure, navigation, weather, and magnetoreception in organisms. The need for continuing observations of the geomagnetic field, together with careful archiving of these records and mechanisms for dissemination of these data, is emphasized.

  12. High frequency cut-off in 1/f conductivity noise of hole-doped La1-x Ca x MnO3 manganite single crystals

    NASA Astrophysics Data System (ADS)

    Przybytek, Jacek; Fink-Finowicki, Jan; Puźniak, Roman; Jung, Grzegorz

    2016-05-01

    High frequency bias and temperature-dependent Lorentzian cut-off has been observed in the 1/f spectra of the conductivity fluctuations in low hole-doped ferromagnetic insulating La1-x Ca x MnO3 manganite at low temperatures. The cut-off frequency depends on dc current bias and temperature. The high frequency cut-off has been tentatively associated with intrinsic limits of the appearance of 1/f noise in the hopping regime of the Coulomb glass state. The assumption is validated by the fact that the Efros-Shklovskii temperature {{T}\\text{ES}} , estimated from the fit of the model to the experimentally measured temperature dependence of the cut-off frequency, has the same value as the temperature {{T}\\text{ES}} evaluated independently from the temperature dependence of the resistivity in the corresponding temperature range.

  13. Elevated d-dimer cut-off values for computed tomography pulmonary angiography—d-dimer correlates with location of embolism

    PubMed Central

    Kubak, Mateuzs Piotr; Borthne, Arne; Ruud, Espen Asak; Ashraf, Haseem

    2016-01-01

    Background Acute pulmonary embolism (APE) is a potentially fatal condition, and making a timely diagnosis can be challenging. Computed tomography pulmonary angiography (CTPA) has become the modality of choice, and this contributes to the increasing load on emergency room CT scanners. Our purpose was to investigate whether an elevated d-dimer cut-off could reduce the demand for CTPA while maintaining a high sensitivity and negative predictive value (NPV). Methods We retrospectively reviewed all patients referred for CTPA with suspicion of APE in 2012, and collected d-dimer values and CTPA results. We investigated the diagnostic performance of d-dimer using a 0.5 mg/L cut-off and an age adjusted cut-off. We also evaluated a new and elevated cut-off. Cases were categorized according to their CTPA result into: no embolism, peripheral embolism, lobar embolism and central embolism. Finally we investigated a possible correlation between d-dimer values and location of embolism. Results We included 1,051 CTPAs, from which 216 (21%) showed pulmonary embolism. There were concomitant d-dimer analyses in 822 CTPA examinations. The current 0.5 mg/L cut-off achieved a sensitivity and NPV of 99%. The age-adjusted cut-off achieved a sensitivity and NPV of 98%, and our suggested cut-off of 0.9 mg/L achieved a sensitivity and NPV of 97%. Conclusions We conclude that the elevated d-dimer cut-off of 0.9 mg/L achieved a high sensitivity and NPV, while reducing the number of CTPA by 27%. The correlation between d-dimer values and location of embolisms supports the suggestion of an elevated d-dimer value. PMID:27386486

  14. Different diagnostic cut-off values of urinary fractionated metanephrines according to sex for the diagnosis of pheochromocytoma in Korean subjects.

    PubMed

    Sohn, Seo Young; Park, Hyung Doo; Lee, Soo Youn; Kim, Jung Han; Jung, Byong Chang; Kim, Hye Jeong; Jang, Hye Won; Kim, Kwang Won; Lee, Moon Kyu; Min, Yong Ki; Kim, Jae Hyeon

    2012-01-01

    The diagnosis of pheochromocytoma depends on the documentation of catecholamine overproduction. The use of urinary fractionated metanephrines has recently become common for the diagnosis of pheochromocytoma. In order to avoid false positive and false negative results, optimal cut-off levels are necessary; however, there have been few published reports on whether different cut-off levels are needed to diagnose pheochromocytoma according to sex. We reviewed the medical records of 815 subjects (including 103 pheochromocytoma patients) whose of 24-h urinary fractionated metanephrine was measured using high-performance liquid chromatography methods and adrenal imaging at Samsung Medical Center. Receiver operating characteristic (ROC) curves were used to determine cut-off values according to sex. The upper limit values of fractionated metanephrine in healthy volunteers and the control group were significantly higher in male subjects compared with females. When we applied cut-off values according to sex, the diagnostic efficacies (defining a positive test as either metanephrine or normetanephrine levels above the cut-off value) were a sensitivity of 96% in male subjects and 98.1% in female subjects and a specificity of 88.6% in male subjects and 94.1% in female subjects. However, when we applied cut-off values without considering sex, the specificity decreased from 88.6% to 77.8% in male subjects. In this study, urinary fractionated metanephrines had a high level of sensitivity and specificity for the diagnosis of pheochromocytoma. However, diagnostic cut-off values were higher in male subjects than in female subjects. Therefore, different cut-off values may be needed according to sex to diagnose pheochromocytoma in Koreans.

  15. Aeromonas Diversity and Antimicrobial Susceptibility in Freshwater—An Attempt to Set Generic Epidemiological Cut-Off Values

    PubMed Central

    Baron, Sandrine; Granier, Sophie A.; Larvor, Emeline; Jouy, Eric; Cineux, Maelan; Wilhelm, Amandine; Gassilloud, Benoit; Le Bouquin, Sophie; Kempf, Isabelle; Chauvin, Claire

    2017-01-01

    The importance of the role of environment in the dissemination of antimicrobial resistant bacteria is now well recognized. Thus, bacterial indicators to monitor the phenomena are required. The Aeromonas genus is autochthonous in the aquatic environment and easy to detect in any water type, such as freshwater, or wastewater. These microorganisms are also causing infections in humans and animals (including fish). Furthermore, as Aeromonas spp. is able to acquire antimicrobial resistance mechanisms, it is candidate for indicator bacteria to follow antimicrobial resistance dissemination in aquatic environments. Unfortunately, to date, interpretation criteria for Aeromonas spp. for antimicrobial susceptibility tests are scarce in the literature. No epidemiological cut-off values for Aeromonas are currently available at EUCAST to interpret Minimum Inhibitory Concentrations (MIC). The only interpretation criteria available are clinical breakpoints from CLSI that are adapted from Enterobacteriaceae. Based on the results of MIC distributions obtained for a collection of environmental isolates of Aeromonas, this study aimed at proposing tentative epidemiological cut-off values (COWT) for Aeromonas spp. assessing whether the genus is an acceptable level of definition. Thus, 233 isolates collected from 16 rivers were identified at species level using Maldi-Tof (Bruker). Eleven different species were identified, the most abundant were A. bestiarum (n = 54), A. salmonicida (n = 45), A. sobria (n = 41), and A. eucrenophila (n = 37). 96-well micro-plates containing different concentrations of 15 antimicrobials, namely cefotaxime, ceftazidime, chloramphenicol, colistin, enrofloxacin, erythromycin, florfenicol, flumequine, gentamicin, nalidixic acid, oxolinic acid, streptomycin, temocillin, tetracycline, and trimethoprim-sulfamethoxazole, were prepared. The broth micro-dilution method was used to determine the antimicrobial susceptibility of each isolate. The estimation of COWT

  16. Bronchodilator response cut-off points and FEV 0.75 reference values for spirometry in preschoolers

    PubMed Central

    Burity, Edjane Figueiredo; Pereira, Carlos Alberto de Castro; Jones, Marcus Herbert; Sayão, Larissa Bouwman; de Andrade, Armèle Dornelas; de Britto, Murilo Carlos Amorim

    2016-01-01

    ABSTRACT Objective: To determine the cut-off points for FEV1, FEV0.75, FEV0.5, and FEF25-75% bronchodilator responses in healthy preschool children and to generate reference values for FEV0.75. Methods: This was a cross-sectional community-based study involving children 3-5 years of age. Healthy preschool children were selected by a standardized questionnaire. Spirometry was performed before and after bronchodilator use. The cut-off point of the response was defined as the 95th percentile of the change in each parameter. Results: We recruited 266 children, 160 (60%) of whom were able to perform acceptable, reproducible expiratory maneuvers before and after bronchodilator use. The mean age and height were 57.78 ± 7.86 months and 106.56 ± 6.43 cm, respectively. The success rate for FEV0.5 was 35%, 68%, and 70% in the 3-, 4-, and 5-year-olds, respectively. The 95th percentile of the change in the percentage of the predicted value in response to bronchodilator use was 11.6%, 16.0%, 8.5%, and 35.5% for FEV1, FEV0.75, FEV0.5, and FEF25-75%, respectively. Conclusions: Our results provide cut-off points for bronchodilator responsiveness for FEV1, FEV0.75, FEV0.5, and FEF25-75% in healthy preschool children. In addition, we proposed gender-specific reference equations for FEV0.75. Our findings could improve the physiological assessment of respiratory function in preschool children. PMID:27812631

  17. Geomagnetic anomaly maps of Central Victoria Land (East Antarctica) from ground measurements

    NASA Astrophysics Data System (ADS)

    Bozzo, E.; Meloni, A.

    1992-10-01

    The results of an extensive ground geomagnetic survey over the Central Victoria Land (East Antarctica) between the Transantarctic Mountains and the Ross Sea are used to plot the residual field map of the area under consideration. The data indicate that intense positive anomalies occur along two corridors, one near Mt. Nansen and the other near Mt. Melbourne. Further elaboration of our measurements has produced three other geomagnetic maps: (1) a high-pass filter (cut-off wavelength of 20 km) map; (2) a low-pass filter (cut-off wavelength of 80 km) map; and (3) an upward continuation of the geomagnetic field up to 12000 ft (3660 m) map. The residual field map and the high-pass filter geomagnetic map indicate that all the intense anomalies (both positive and negative) are of shallow origin. The low pass filter map and the upward continuation map show that the land mass of the Central Victoria Land is characterized-by a weak, negative geomagnetic anomaly whereas the near-shore area, close to Terra Nova Bay, displays a weak positive anomaly. Our measurements indicate that all rock types characterized by high susceptibility produce geomagnetic anomalies, even if their outcrop is not extensive. These rocks belong to the Mt. Melbourne volcanics, Jurassic dolerites and Granite Harbour plutons. None of the formations of the metamorphic complex are responsible for intense magnetic signals.

  18. Improving the intrinsic cut-off frequency of gate-all-around quantum-wire transistors without channel length scaling

    NASA Astrophysics Data System (ADS)

    Benali, A.; Traversa, F. L.; Albareda, G.; Aghoutane, M.; Oriols, X.

    2013-04-01

    Progress in high-frequency transistors is based on reducing electron transit time, either by scaling their lengths or by introducing materials with higher electron mobility. For gate-all-around quantum-wire transistors with lateral dimensions similar or smaller than their length, a careful analysis of the displacement current reveals that a time shorter than the transit time controls their high-frequency performance. Monte Carlo simulations of such transistors with a self-consistent solution of the 3D Poisson equation clearly show an improvement of the intrinsic cut-off frequency when their lateral areas are reduced, without length scaling.

  19. Cut-Off Value of Total Adiponectin for Managing Risk of Developing Metabolic Syndrome in Male Japanese Workers

    PubMed Central

    Hata, Akiko; Yonemoto, Koji; Shikama, Yosuke; Aki, Nanako; Kosugi, Chisato; Tamura, Ayako; Ichihara, Takako; Minagawa, Takako; Kuwamura, Yumi; Miyoshi, Masashi; Nakao, Takayuki; Funaki, Makoto

    2015-01-01

    Aim To determine the optimal cut-off value of serum total adiponectin for managing the risk of developing metabolic syndrome (MetS) in male Japanese workers. Methods A total of 365 subjects without MetS aged 20–60 years were followed up prospectively for a mean of 3.1 years. The accelerated failure-time model was used to estimate time ratio (TR) and cut-off value for developing MetS. Results During follow-up, 45 subjects developed MetS. Age-adjusted TR significantly declined with decreasing total adiponectin level (≤ 4.9, 5.0–6.6, 6.7–8.8 and ≥ 8.9 μg/ml, P for trend = 0.003). In multivariate analyses, TR of MetS was 0.12 (95% CI 0.02–0.78; P = 0.03) in subjects with total adiponectin level of 5.0–6.6 μg/ml, and 0.15 (95% CI 0.02–0.97; P = 0.047) in subjects with total adiponectin level ≤ 4.9 μg/ml compared with those with total adiponectin level ≥ 8.9 μg/ml. The accelerated failure-time model showed that the optimal cut-off value of total adiponectin for managing the risk of developing MetS was 6.2 μg/ml. In the multivariate-adjusted model, the mean time to the development of MetS was 78% shorter for total adiponectin level ≤ 6.2 μg/ml compared with > 6.2 μg/ml (TR 0.22, 95% CI: 0.08–0.64, P = 0.005). Conclusion Our findings suggest that the cut-off value for managing the risk of developing MetS is 6.2 μg/ml in male Japanese workers. Subjects with total adiponectin level ≤ 6.2 μg/ml developed MetS more rapidly than did those with total adiponectin level > 6.2 μg/ml. PMID:25705909

  20. Interstellar flow direction from pickup ion cut-off dependence on longitude, flow and solar wind speed

    NASA Astrophysics Data System (ADS)

    Möbius, Eberhard; Lee, Martin A.; Drews, Christian; Gloeckler, George

    2016-03-01

    The precise interstellar neutral (ISN) flow direction is important because of its strong leverage on the plane subtended by the ISN and magnetic field vectors, which controls the heliospheric shape and interaction with the interstellar medium. IBEX measurements provide a very precise relation between ISN flow longitude and speed via the hyperbolic trajectory equation, forming a 4-dimensional tube in the ISN parameter space, with substantially larger uncertainty along this tube and thus for the longitude alone. As demonstrated before, the interstellar pickup ion (PUI) cut-off speed is a function of the ratio of the radial ISN flow component and the solar wind speed at the observer location. The former is largest precisely upwind and decreases symmetrically with the angle from the upwind direction. Using this functional dependence and the observed solar wind speed, the PUI cut-off can be constructed solely as a function of the ISN flow longitude. From ACE SWICS and STEREO PLASTIC, data sets that span 18+ years are available. We will show, in particular, that by selecting observations for local interplanetary magnetic fields perpendicular to the solar wind and transforming the observed distributions into the solar wind frame, a comparison with data can be devised that is much less sensitive to PUI production and transport effects than methods that rely on pickup ion fluxes.

  1. Determination of the accuracy and optimal cut-off point for ELISA test in diagnosis of human brucellosis in Iran.

    PubMed

    Hasibi, Mehrdad; Jafari, Sirus; Mortazavi, Habibollah; Asadollahi, Marjan; Esmaeeli Djavid, Gholamreza

    2013-01-01

    In endemic area the most challenging problem for brucellosis is to find a reliable diagnostic method. In this case-control study, we investigated the accuracy of ELISA test for diagnosis of human brucellosis and determined the optimal cut-off value for ELISA results in Iran. The laboratory diagnosis of brucellosis was performed by blood isolation of Brucella organism with a BACTEC 9240 system and/or detection of Brucella antibodies by standard agglutination test (titer ≥ 1:160). Serum level of ELISA IgG and ELISA IgM from 56 confirmed cases of brucellosis and 126 controls were compared with each other by Box plot graph and Receiver Operating Characteristic (ROC) curve. Box plot graphs showed the high degree of dispersion for IgG and IgM data in patients compared with all controls. We observed partially overlapping for IgM data (not for IgG) between cases and controls in graphs. The area under ROC curve for distinguishing between cases and controls was larger for IgG compared to IgM. Based on results of this study, ELISA IgG test was more reliable than ELISA IgM test in diagnosis of human brucellosis in Iran. Using a cut-off of 10 IU/ml and 50 IU/ml had most sensitivity (92.9%) and most specificity (100%) for ELISA IgG test, respectively.

  2. Cut-off scaling of high-harmonic generation driven by a femtosecond visible optical parametric amplifier

    NASA Astrophysics Data System (ADS)

    Cirmi, Giovanni; Lai, Chien-Jen; Granados, Eduardo; Huang, Shu-Wei; Sell, Alexander; Hong, Kyung-Han; Moses, Jeffrey; Keathley, Phillip; Kärtner, Franz X.

    2012-10-01

    We studied high-harmonic generation (HHG) in Ar, Ne and He gas jets using a broadly tunable, high-energy optical parametric amplifier (OPA) in the visible wavelength range. We optimized the noncollinear OPA to deliver tunable, femtosecond pulses with 200-500 µJ energy at the 1 kHz repetition rate with excellent spatiotemporal properties, suitable for HHG experiments. By tuning the central wavelength of the OPA while keeping other parameters (energy, duration and beam size) constant, we experimentally studied the scaling law of cut-off energy with the driver wavelength in helium. Our measurements show a λ1.7 + 0.2 dependence of the HHG cut-off photon energy over the full visible range in agreement with previous experiments of near- and mid-IR wavelengths. By tuning the central wavelength of the driver source, the high-order harmonic spectra in the extreme ultraviolet cover the full range of photon energy between ˜25 and ˜100 eV. Due to the high coherence intrinsic in HHG, as well as the broad and continuous tunability in the extreme UV range, a high energy, high repetition rate version of this source might be an ideal seed for free electron lasers.

  3. STS-114: Engine Cut-Off Sensors Are a No-Go: Teaching Notes for NASA Case Study

    NASA Technical Reports Server (NTRS)

    Ransom, Khadijah S.; Johnson, Grace K.

    2013-01-01

    This case study format is intended to simulate the experience of facing the same difficult challenges and making the same critical decisions as managers, engineers, and scientists in the Space Shuttle Program. It has been designed for use in the classroom setting to help students develop skills related to decision-making. Students will read about the engine cut-off sensor anomaly which created challenges during the STS-114 mission and have the opportunity to make decisions as lead NASA engineers and Mission Management Team members. Included within this document are three case study presentation options - class discussion, group activity, and open-ended research. Please read the full case prior to in-class presentation to allow ample time for students' analysis and reflection, as well as to prepare additional questions. activities or exercises, material selection, etc. Depending upon the setting of your presentation and the number of participants, please choose at least one presentation format beforehand and plan accordingly. You may expect the following learning objectives by using the proposed formats. Learning Objectives: To enable students to experience the responsibilities of NASA management, engineers, and analysis; to discover possible procedures for investigating system anomalies; to become familiar with the liquid hydrogen low level engine cut-off sensor, including its function, connecting components, and location within the Space Shuttle; and to encourage critical analysis and stimulating discussion of Space Shuttle mission challenges.

  4. Accuracy of cut-off value by measurement of third molar index: Study of a Colombian sample.

    PubMed

    De Luca, Stefano; Aguilar, Lina; Rivera, Marcela; Palacio, Luz Andrea Velandia; Riccomi, Giulia; Bestetti, Fiorella; Cameriere, Roberto

    2016-04-01

    The aim of this cross-sectional study was to test the accuracy of cut-off value of 0.08 by measurement of third molar index (I3M) in assessing legal adult age of 18 years in a sample of Colombian children and young adults. Digital orthopantomographs of 288 Colombian children and young adults (163 girls and 125 boys), aged between 13 and 22 years, were analysed. Concordance correlation coefficient (ρc) and κ statistics (Cohen's Kappa coefficient) showed that repeatability and reproducibility are high for both intra- and inter-observer error. κ statistics for intra- and inter-observer agreement in decision on adult or minor was 0.913 and 0.877, respectively. Age distribution gradually decreases as I3M increases in both girls and boys. For girls, the sensitivity test was 95.1% (95% CI 87.1%-95%) and specificity was 93.8% (95% CI 87.1%-98.8%). The proportion of correctly classified individuals was 95.1%. For boys, the sensitivity test was 91.7% (95% CI 85.1%-96.8%) and specificity was 90.6% (95% CI 82.1%-97.8%). The proportion of correctly classified individuals was 89.7%. The cut-off value of 0.08 is highly useful to determine if a subject is 18 years of age or older or not.

  5. The cut-off values of anthropometric variables for predicting mild cognitive impairment in Malaysian older adults: a large population based cross-sectional study

    PubMed Central

    Won, Huiloo; Abdul, Manaf Zahara; Mat Ludin, Arimi Fitri; Omar, Mohd Azahadi; Razali, Rosdinom; Shahar, Suzana

    2017-01-01

    Purpose Older adults are at risk of mild cognitive impairment (MCI), and simple anthropometric measurements can be used to screen for this condition. Thus, the aim of this study was to explore the cut-off values of body mass index (BMI) and waist circumference (WC) for predicting the risk of MCI in older Malaysian adults. Methods A total of 2,240 Malaysian older adults aged ≥60 years were recruited using multistage random sampling in a population based cross-sectional study. Receiver operating characteristic (ROC) curve was used to determine the cut-off values of BMI and WC with optimum sensitivity and specificity for the detection of MCI. Age, gender, years of education, smoking habit, alcohol consumption, depression, and medical conditions were used as confounding factors in this analysis. Results A BMI cut-off value of 26 kg/m2 (area under the receiver operating characteristic curve [AUC] 0.725; sensitivity 90.5%; specificity 38.8%) was appropriate in identifying the risk of getting MCI in both men and women. The optimum WC cut-offs for likelihood of MCI were 90 cm (AUC 0.745; sensitivity 78.0%; specificity 59.8%) for men and 82 cm (AUC 0.714; sensitivity 84.3%; specificity 49.7%) for women. The optimum calf circumference (CC) cut-off values for identifying MCI were 29 cm (AUC 0.731; sensitivity 72.6%; specificity 61.1%) for men and 26 cm (AUC 0.598; sensitivity 79.1%; specificity 45.3%) for women. Conclusion The cut-off values could be advocated and used as part of the screening of MCI among older Malaysian adults. There is a need to further determine the predictive values of these cut-off points on outcomes through longitudinal study design. PMID:28223785

  6. The impact of an underground cut-off wall on nutrient dynamics in groundwater in the lower Wang River watershed, China.

    PubMed

    Kang, Pingping; Xu, Shiguo

    2017-03-01

    Underground cut-off walls in coastal regions are mainly used to prevent saltwater intrusion, but their impact on nutrient dynamics in groundwater is not clear. In this study, a combined analysis of multiple isotopes ([Formula: see text]) and nitrogen and phosphorus concentrations is used in order to assess the impact of the underground cut-off walls on the nutrient dynamics in groundwater in the lower Wang River watershed, China. Compared with the nitrogen and phosphorus concentrations in groundwater downstream of the underground cut-off walls, high [Formula: see text] and total dissolved nitrogen concentrations and similar concentration levels of [Formula: see text] and total dissolved phosphorus are found in groundwater upstream of the underground cut-off walls. The isotopic data indicated the probable occurrence of denitrification and nitrification processes in groundwater upstream, whereas the fingerprint of these processes was not shown in groundwater downstream. The management of fertilizer application is critical to control nitrogen concentrations in groundwater restricted by the underground cut-off walls.

  7. Psychometric properties and clinical cut-off scores of the Spanish version of the Social Anxiety Scale for Adolescents.

    PubMed

    Garcia-Lopez, Luis J; Inglés, Cándido J; García-Fernández, José M; Hidalgo, María D; Bermejo, Rosa; Puklek Levpušček, Melita

    2011-01-01

    This study examined the reliability and validity evidence drawn from the scores of the Spanish version of the Slovenian-developed Social Anxiety Scale for Adolescents (SASA; Puklek, 1997; Puklek & Vidmar, 2000) using a community sample (Study 1) and a clinical sample (Study 2). Confirmatory factor analysis in Study 1 replicated the 2-factor structure found by the original authors in a sample of Slovenian adolescents. Test-retest reliability was adequate. Furthermore, the SASA correlated significantly with other social anxiety scales, supporting concurrent validity evidence in Spanish adolescents. The results of Study 2 confirmed the correlations between the SASA and other social anxiety measures in a clinical sample. In addition, findings revealed that the SASA can effectively discriminate between adolescents with a clinical diagnosis of social anxiety disorder (SAD) and those without this disorder. Finally, cut-off scores for the SASA are provided for Spanish adolescents.

  8. A new perspective of the climatological features of upper-level cut-off lows in the Southern Hemisphere

    NASA Astrophysics Data System (ADS)

    Pinheiro, Henri Rossi; Hodges, Kevin Ivan; Gan, Manoel Alonso; Ferreira, Nelson Jesuz

    2017-01-01

    This study presents a detailed view of the seasonal variability of upper-level cut-off lows (COLs) in the Southern Hemisphere. The COLs are identified and tracked using data from a 36-year period of the European Centre for Medium Range Weather Forecast reanalysis (ERA-Interim). The objective identification of the COLs uses a new approach, which is based on 300 hPa relative vorticity minima, and three restrictive criteria of the presence of a cold-core, stratospheric potential vorticity intrusion, and cut-off cyclonic circulation. The highest COL activity is in agreement with previous studies, located near three main continental areas (Australia, South America, and Africa), with maximum frequencies usually observed in the austral autumn. The COL mean intensity values show a marked seasonal and spatial variation, with maximum (minimum) values during the austral winter (summer), a unique feature that has not been observed previously in studies based on the geopotential. The link between intensity and lysis is examined, and finds that weaker systems are more susceptible to lysis in the vicinity of the Andes Cordillera, associated with the topographic Rossby wave. Lysis and genesis regions are close to each other, confirming that COLs are quasi-stationary systems. Also, COLs tend to move eastward and are faster over the higher latitudes. The mean growth/decay rates coincide with the major genesis and lysis density regions, such as the significant decay values across the Andes all year. As a consequence of using vorticity for the tracking method a longer lifetime of COLs is detected than in other studies, but this does not affect the total frequency of occurrence. Comparisons with other studies suggest that the differences in seasonality are due to uncertainties in the reanalyses and the methods used to identify COLs.

  9. Use of the Azimuth Wavelength Cut-Off to Retrieve the Sea Surface Wind Speed from Sentinel 1 and COSMO-SkyMed SAR Data

    NASA Astrophysics Data System (ADS)

    Grieco, G.; Nirchio, F.; Montuori, A.; Migliaccio, M.; Lin, W.; Portabella, M.

    2016-08-01

    The dependency of the azimuth wavelength cut-off on the wind speed has been studied through a dataset of Sentinel-1 multi look SAR images co-located with wind speed measurements, significant wave height and mean wave direction from ECMWF operational output.A Geophysical Model Function (GMF) has been fitted and a retrieval exercise has been done comparing the results to a set of independent wind speed scatterometer measurements of the Chinese mission HY-2A. The preliminary results show that the dependency of the azimuth cut-off on the wind speed is linear only for fully developed sea states and that the agreement between the retrieved values and the measurements is good especially for high wind speed.A similar approach has been used to assess the dependency of the azimuth cut-off also for X-band COSMO-SkyMed data. The dataset is still incomplete but the preliminary results show a similar trend.

  10. Cut-Offs and Response Criteria for the Hospital Universitario La Princesa Index (HUPI) and Their Comparison to Widely-Used Indices of Disease Activity in Rheumatoid Arthritis

    PubMed Central

    Castrejón, Isabel; Ortiz, Ana M.; Toledano, Esther; Castañeda, Santos; García-Vadillo, Alberto; Carmona, Loreto

    2016-01-01

    Objective To estimate cut-off points and to establish response criteria for the Hospital Universitario La Princesa Index (HUPI) in patients with chronic polyarthritis. Methods Two cohorts, one of early arthritis (Princesa Early Arthritis Register Longitudinal [PEARL] study) and other of long-term rheumatoid arthritis (Estudio de la Morbilidad y Expresión Clínica de la Artritis Reumatoide [EMECAR]) including altogether 1200 patients were used to determine cut-off values for remission, and for low, moderate and high activity through receiver operating curve (ROC) analysis. The areas under ROC (AUC) were compared to those of validated indexes (SDAI, CDAI, DAS28). ROC analysis was also applied to establish minimal and relevant clinical improvement for HUPI. Results The best cut-off points for HUPI are 2, 5 and 9, classifying RA activity as remission if ≤2, low disease activity if >2 and ≤5), moderate if >5 and <9 and high if ≥9. HUPI’s AUC to discriminate between low-moderate activity was 0.909 and between moderate-high activity 0.887. DAS28’s AUCs were 0.887 and 0.846, respectively; both indices had higher accuracy than SDAI (AUCs: 0.832 and 0.756) and CDAI (AUCs: 0.789 and 0.728). HUPI discriminates remission better than DAS28-ESR in early arthritis, but similarly to SDAI. The HUPI cut-off for minimal clinical improvement was established at 2 and for relevant clinical improvement at 4. Response criteria were established based on these cut-off values. Conclusions The cut-offs proposed for HUPI perform adequately in patients with either early or long term arthritis. PMID:27603313

  11. Age-related differences in recommended anthropometric cut-off point validity to identify cardiovascular risk factors in ostensibly healthy women

    PubMed Central

    Björkelund, Cecilia; Guo, Xinxin; Skoog, Ingmar; Bosaeus, Ingvar; Lissner, Lauren

    2014-01-01

    Aim: To investigate validity of widely recommended anthropometric and total fat percentage cut-off points in screening for cardiovascular risk factors in women of different ages. Methods: A population-based sample of 1002 Swedish women aged 38, 50, 75 (younger, middle-aged and elderly, respectively) underwent anthropometry, health examinations and blood tests. Total fat was estimated (bioimpedance) in 670 women. Sensitivity, specificity of body mass index (BMI; ≥25 and ≥30), waist circumference (WC; ≥80 cm and ≥88 cm) and total fat percentage (TF; ≥35%) cut-off points for cardiovascular risk factors (dyslipidaemias, hypertension and hyperglycaemia) were calculated for each age. Cut-off points yielding high sensitivity together with modest specificity were considered valid. Women reporting hospital admission for cardiovascular disease were excluded. Results: The sensitivity of WC ≥80 cm for one or more risk factors was ~60% in younger and middle-aged women, and 80% in elderly women. The specificity of WC ≥80 cm for one or more risk factors was 69%, 57% and 40% at the three ages (p < .05 for age trends). WC ≥80 cm yielded ~80% sensitivity for two or more risk factors across all ages. However, specificity decreased with increasing age (p < .0001), being 33% in elderly. WC ≥88 cm provided better specificity in elderly women. BMI and TF % cut-off points were not better than WC. Conclusions: Validity of recommended anthropometric cut-off points in screening asymptomatic women varies with age. In younger and middle-age, WC ≥80 cm yielded high sensitivity and modest specificity for two or more risk factors, however, sensitivity for one or more risk factor was less than optimal. WC ≥88 cm showed better validity than WC ≥80 cm in elderly. Our results support age-specific screening cut-off points for women. PMID:25294689

  12. Comparison of Interferon-γ Release Assay to Two Cut-Off Points of Tuberculin Skin Test to Detect Latent Mycobacterium tuberculosis Infection in Primary Health Care Workers

    PubMed Central

    de Souza, Fernanda Mattos; do Prado, Thiago Nascimento; Pinheiro, Jair dos Santos; Peres, Renata Lyrio; Lacerda, Thamy Carvalho; Loureiro, Rafaela Borge; Carvalho, Jose Américo; Fregona, Geisa; Dias, Elias Santos; Cosme, Lorrayne Beliqui; Rodrigues, Rodrigo Ribeiro; Riley, Lee Wood; Maciel, Ethel Leonor Noia

    2014-01-01

    Background An interferon-γ release assay, QuantiFERON-TB (QFT) test, has been introduced an alternative test for the diagnosis of latent Mycobacterium tuberculosis infection (LTBI). Here, we compared the performance of QFT with tuberculin skin test (TST) measured at two different cut-off points among primary health care work (HCW) in Brazil. Methods A cross-sectional study was carried out among HCWs in four Brazilian cities with a known history of high incidence of TB. Results of the QFT were compared to TST results based on both ≥5 mm and ≥10 mm as cut-off points. Results We enrolled 632 HCWs. When the cut-off value of ≥10 mm was used, agreement between QFT and TST was 69% (k = 0.31), and when the cut-off of ≥5 mm was chosen, the agreement was 57% (k = 0.22). We investigated possible factors of discordance of TST vs QFT. Compared to the TST−/QFT− group, risk factors for discordance in the TST+/QFT− group with TST cut-off of ≥5 mm included age between 41–45 years [OR = 2.70; CI 95%: 1.32–5.51] and 46–64 years [OR = 2.04; CI 95%: 1.05–3.93], BCG scar [OR = 2.72; CI 95%: 1.40–5.25], and having worked only in primary health care [OR = 2.30; CI 95%: 1.09–4.86]. On the other hand, for the cut-off of ≥10 mm, BCG scar [OR = 2.26; CI 95%: 1.03–4.91], being a household contact of a TB patient [OR = 1.72; CI 95%: 1.01–2.92] and having had a previous TST [OR = 1.66; CI 95%: 1.05–2.62], were significantly associated with the TST+/QFT− group. No statistically significant associations were found among the TST−/QFT+ discordant group with either TST cut-off value. Conclusions Although we identified BCG vaccination to contribute to the discordance at both TST cut-off measures, the current Brazilian recommendation for the initiation of LTBI treatment, based on information gathered from medical history, TST, chest radiograph and physical examination, should not be changed. PMID:25137040

  13. Evaluation of total body weight and body mass index cut-offs for increased cefazolin dose for surgical prophylaxis.

    PubMed

    Hites, Maya; Deprez, Guillaume; Wolff, Fleur; Ickx, Brigitte; Verleije, Anita; Closset, Jean; Loi, Patrizia; Prévost, Jessica; Taccone, Fabio S; Racapé, Judith; Cotton, Frédéric; Jacobs, Frédérique

    2016-12-01

    French and American guidelines recommend increased dosage regimens of cefazolin (CFZ) for surgical prophylaxis in patients with a body mass index (BMI) ≥ 35 kg/m(2) or with a total body weight (TBW) ≥ 120 kg. The objective of this study was to evaluate the accuracy of these cut-offs in identifying patients who require CFZ dose adjustment. A pharmacokinetic study was conducted in patients of varying TBW and BMI who received 2 g of CFZ intravenously for prophylaxis prior to digestive surgery. Adequacy of therapy, defined as a serum concentration of unbound CFZ (fCFZ) ≥ 4 mg/L, was evaluated 180 min (T180) and 240 min (T240) after the start of CFZ infusion. Possible factors associated with insufficient fCFZ levels were also assessed. A P-value of <0.05 was considered statistically significant. A total of 63 patients were included in the study, categorised according to BMI (<35 kg/m(2), 20 patients; and ≥35 kg/m(2), 43 patients) and TBW (<120 kg, 41 patients; and ≥120 kg, 22 patients). All patients had adequate drug levels at T180 but only 40/63 patients (63%) had adequate levels at T240. At T240, therapy was adequate in 15/20 patients (75%) and 25/43 patients (58%) with BMI <35 kg/m(2) and ≥35 kg/m(2), respectively (P = 0.20), and in 28/41 patients (68%) and 12/22 patients (55%) with TBW <120 kg and ≥120 kg, respectively (P = 0.28). No factor associated with insufficient fCFZ was identified. In conclusion, current BMI and TBW cut-offs are poor indicators of which patients could benefit from increased CFZ dosage regimens.

  14. Prevalence of the metabolic syndrome and determination of optimal cut-off values of waist circumference in university employees from Angola

    PubMed Central

    Magalhães, Pedro; Capingana, Daniel P; Mill, José G

    2014-01-01

    Summary Background Estimates of the prevalence of the metabolic syndrome in Africans may be inconsistent due to lack of African-specific cut-off values of waist circumference (WC). This study determined the prevalence of the metabolic syndrome and defined optimal values of WC in Africans. Methods This cross-sectional study collected demographic, anthropometric and clinical data of 615 Universitary employees, in Luanda, Angola. The metabolic syndrome was defined using the third report of the National Cholesterol Education Program Adult Treatment Panel (ATPIII) and the Joint Interim Statement (JIS) criteria. Receiver operating characteristics curves were constructed to assess cut-off values of WC. Results The crude prevalence of the metabolic syndrome was higher with the JIS definition (27.8%, age-standardised 14.1%) than with the ATP III definition (17.6%, age-standardised 8.7%). Optimal cut-off values of WC were 87.5 and 80.5 cm in men and women, respectively. Conclusions There was a high prevalence of the metabolic syndrome among our African subjects. Our data suggest different WC cut-off values for Africans in relation to other populations. PMID:24626517

  15. Cosmological properties and reconstruction of scalar field models of the Holographic Dark Energy model with Granda-Oliveros cut-off in Kaluza-Klein cosmology

    NASA Astrophysics Data System (ADS)

    Pasqua, Antonio; Chattopadhyay, Surajit; Assaf, Khudhair A.; Salako, Ines G.

    2016-06-01

    In this paper, we study the properties of the Holographic Dark Energy (HDE) model in the context of Kaluza-Klein (KK) cosmology with infrared cut-off given by the recently proposed by Granda-Oliveros cut-off, which contains a term proportional to the time derivative of the Hubble parameter and one proportional to the Hubble parameter squared. Moreover, this cut-off is characterized by two free parameters which are the proportional constants of the two terms of the cut-off. We derive the expression of the Equation of State (EoS) parameter ωD and of the deceleration parameter q for both non-interacting and interacting Dark Sectors and in the limiting case of a flat Dark Dominated Universe. Moreover, we study the squared speed of the sound vs2 and the statefinder diagnostic \\{r,s\\} in order to understand the cosmological properties of the model considered. We also develop a correspondence between the model considered and three scalar field models: the tachyon, the k-essence and the quintessence ones.

  16. Estimation of Saliva Cotinine Cut-Off Points for Active and Passive Smoking during Pregnancy-Polish Mother and Child Cohort (REPRO_PL).

    PubMed

    Polanska, Kinga; Krol, Anna; Kaluzny, Pawel; Ligocka, Danuta; Mikolajewska, Karolina; Shaheen, Seif; Walton, Robert; Hanke, Wojciech

    2016-12-08

    A reliable assessment of smoking status has significant public health implications and is essential for research purposes. The aim of this study was to determine optimal saliva cotinine cut-off values for smoking during pregnancy. The analyses were based on data from 1771 women from the Polish Mother and Child Cohort. Saliva cotinine concentrations were assessed by high performance liquid chromatography coupled with tandem mass spectrometry (HPLC-ESI + MS/MS). The saliva cotinine cut-off value for active smoking was established at 10 ng/mL (sensitivity 96%, specificity 95%) and for passive smoking at 1.5 ng/mL (sensitivity 63%, specificity 71%). About 5% of the self-reported non-smoking women were classified as smokers based on the cotinine cut-off value. Significantly more younger, single, and less educated self-reported non-smokers had a cotinine concentration higher than 10 ng/mL compared to those who were older, married, and who had a university degree. Close to 30% of the non-smokers who indicated that smoking was not allowed in their home could be classified as exposed to passive smoking based on the cut-off value. The study suggests that self-reported smoking status is a valid measure of active smoking, whereas in the case of passive smoking, a combination of questionnaire data and biomarker verification may be required.

  17. Enhanced Narrow-band, Coherent Emission from a Current Source Immersed in Cut-off of a Plasma-like Medium

    NASA Astrophysics Data System (ADS)

    Hur, Min Sup; Ersfeld, Bernhard; Noble, Adam; Suk, Hyyong; Jaroszynski, Dino

    2016-10-01

    In plasma-like media sharing a similar dispersion relation, there exists a cut-off frequency to make the wave number zero. This particular situation has been understood classically in a way that the radiation impedance becomes infinite, resulting in a total reflection of an incident wave. However, in this framework of understanding the cut-off, a pure current source immersed in the cut-off region leads to infinite radiation power from Ohm's law. This is obviously unphysical and requires a different approach to address the problem. In this presentation, we show that by solving the driven time-dependent Schrödinger equation, the radiation at the cut-off frequency can be selectively enhanced by several times the pure vacuum-emission. Important question here is whether such current sources are available in practical systems. We find that quasi-current sources are actually ubiquitous as long as the conversion efficiency from the current driver to the radiation emission is low. We demonstrate two such cases by PIC simulations; THz radiation from a plasma driven by colliding laser pulses, and THz from two-color lasers enclosed by a tapered waveguide. We also discuss the previous experimental results in terms of this enhanced emission concept.

  18. Estimation of Saliva Cotinine Cut-Off Points for Active and Passive Smoking during Pregnancy—Polish Mother and Child Cohort (REPRO_PL)

    PubMed Central

    Polanska, Kinga; Krol, Anna; Kaluzny, Pawel; Ligocka, Danuta; Mikolajewska, Karolina; Shaheen, Seif; Walton, Robert; Hanke, Wojciech

    2016-01-01

    A reliable assessment of smoking status has significant public health implications and is essential for research purposes. The aim of this study was to determine optimal saliva cotinine cut-off values for smoking during pregnancy. The analyses were based on data from 1771 women from the Polish Mother and Child Cohort. Saliva cotinine concentrations were assessed by high performance liquid chromatography coupled with tandem mass spectrometry (HPLC-ESI + MS/MS). The saliva cotinine cut-off value for active smoking was established at 10 ng/mL (sensitivity 96%, specificity 95%) and for passive smoking at 1.5 ng/mL (sensitivity 63%, specificity 71%). About 5% of the self-reported non-smoking women were classified as smokers based on the cotinine cut-off value. Significantly more younger, single, and less educated self-reported non-smokers had a cotinine concentration higher than 10 ng/mL compared to those who were older, married, and who had a university degree. Close to 30% of the non-smokers who indicated that smoking was not allowed in their home could be classified as exposed to passive smoking based on the cut-off value. The study suggests that self-reported smoking status is a valid measure of active smoking, whereas in the case of passive smoking, a combination of questionnaire data and biomarker verification may be required. PMID:27941658

  19. Epidemiologic Behavior and Estimation of an Optimal Cut-Off Point for Homeostasis Model Assessment-2 Insulin Resistance: A Report from a Venezuelan Population

    PubMed Central

    Bermúdez, Valmore; Martínez, María Sofía; Apruzzese, Vanessa; Chávez-Castillo, Mervin; Gonzalez, Robys; Torres, Yaquelín; Bello, Luis; Añez, Roberto; Chacín, Maricarmen; Toledo, Alexandra; Cabrera, Mayela; Mengual, Edgardo; Ávila, Raquel; López-Miranda, José

    2014-01-01

    Background. Mathematical models such as Homeostasis Model Assessment have gained popularity in the evaluation of insulin resistance (IR). The purpose of this study was to estimate the optimal cut-off point for Homeostasis Model Assessment-2 Insulin Resistance (HOMA2-IR) in an adult population of Maracaibo, Venezuela. Methods. Descriptive, cross-sectional study with randomized, multistaged sampling included 2,026 adult individuals. IR was evaluated through HOMA2-IR calculation in 602 metabolically healthy individuals. For cut-off point estimation, two approaches were applied: HOMA2-IR percentile distribution and construction of ROC curves using sensitivity and specificity for selection. Results. HOMA2-IR arithmetic mean for the general population was 2.21 ± 1.42, with 2.18 ± 1.37 for women and 2.23 ± 1.47 for men (P = 0.466). When calculating HOMA2-IR for the healthy reference population, the resulting p75 was 2.00. Using ROC curves, the selected cut-off point was 1.95, with an area under the curve of 0.801, sensibility of 75.3%, and specificity of 72.8%. Conclusions. We propose an optimal cut-off point of 2.00 for HOMA2-IR, offering high sensitivity and specificity, sufficient for proper assessment of IR in the adult population of our city, Maracaibo. The determination of population-specific cut-off points is needed to evaluate risk for public health problems, such as obesity and metabolic syndrome. PMID:27379332

  20. On a holographic dark energy model with a Nojiri-Odintsov cut-off in general relativity

    NASA Astrophysics Data System (ADS)

    Khurshudyan, Martiros

    2016-07-01

    In this paper we consider the models of the accelerated expanding large scale universe (according to general relativity) containing a generalized holographic dark energy with a Nojiri-Odintsov cut-off. The second component of the darkness is assumed to be the pressureless cold dark matter according to observed symmetries of the large scale universe. Moreover, we assume specific forms of the interaction between these two components and besides the cosmographic analysis, we discuss appropriate results from Om and Om3 analysis and organize a closer look to the models via the statefinder hierarchy analysis, too. In this way we study mainly impact of the interaction on the dynamics of the background of our universe (within specific forms of interaction). To complete the cosmographic analysis, the present day values of the statefinder parameters (r,s) and (ω^'_{de}, ω_{de}) has been estimated for all cases and the validity of the generalized second law of thermodynamics is demonstrated. Our study showed that theoretical results from considered phenomenological models are consistent with the available observational data and symmetries.

  1. Kinetic Isotope Effects from QM/MM Subset Hessians: "Cut-Off" Analysis for SN2 Methyl Transfer in Solution.

    PubMed

    Williams, Ian H

    2012-02-14

    Isotopic partition-function ratios and kinetic isotope effects for reaction of S-adenosylmethionine with catecholate in water are evaluated using a subset of 324 atoms within its surrounding aqueous environment at the AM1/TIP3P level. Two alternative methods for treating motion in the six librational degrees of freedom of the subset atoms relative to their environment are compared. A series of successively smaller subset Hessians are generated by cumulative deletion of rows and columns from the initial 972 × 972 Hessian. We find that it is better to treat these librations as vibrations than as translations and rotations and that there is no need to invoke the Teller-Redlich product rule. The validity of "cut-off" procedures for computation of isotope effects with truncated atomic subsets is assessed: to ensure errors in ln(KIE) < 1% (or 2% for the quantum-corrected KIE) for all isotopic substitutions considered, it is necessary to use a less-restrictive procedure than is suggested by the familiar two-bond cutoff rule.

  2. Optimal Cut-Off Value of the Superior Articular Process Area as a Morphological Parameter to Predict Lumbar Foraminal Stenosis

    PubMed Central

    Lim, Tae-Ha; Choi, Soo Il; Cho, Hyung Rae; Kang, Keum Nae; Rhyu, Chang Joon; Chae, Eun Young; Lim, Young Su; Lee, Yongsoo

    2017-01-01

    Background. We devised a new morphological parameter called the superior articular process area (SAPA) to evaluate the connection between lumbar foraminal stenosis (LFS) and the superior articular process. Objective. We hypothesized that the SAPA is an important morphologic parameter in the diagnosis of LFS. Methods. All patients over 60 years of age were included. Data regarding the SAPA were collected from 137 patients with LFS. A total of 167 control subjects underwent lumbar magnetic resonance imaging (MRI) as part of a routine medical examination. We analyzed the cross-sectional area of the bone margin of the superior articular process at the level of L4-L5 facet joint in the axial plane. Results. The average SAPA was 96.3 ± 13.6 mm2 in the control group and 128.1 ± 17.2 mm2 in the LFS group. The LFS group was found to have significantly higher levels of SAPA (p < 0.001) in comparison to the control group. In the LFS group, the optimal cut-off value was 112.1 mm2, with 84.4% sensitivity, 83.9% specificity, and AUC of 0.94 (95% CI: 0.91–0.96). Conclusions. Higher SAPA values were associated with a higher possibility of LFS. These results are important in the evaluation of patients with LFS. PMID:28163566

  3. The acid phosphatase test two minute cut-off: an insufficient time to detect some semen stains.

    PubMed

    Redhead, Paul; Brown, Melanie K

    2013-06-01

    The ability to detect semen in sexual offence cases is a crucial first step to locating stains which may be suitable for DNA profiling. Since the development of the acid phosphatase test in the late 1950s by Stuart S. Kind, the process undertaken to perform the test has gone largely unchanged. The method currently accepted by operational forensic science laboratories allows 2 min for a reaction to be obtained, and until relatively recently, this has not been challenged. In this research, samples of semen were obtained from three donors and a range of dilutions for each sample were prepared. Each dilution was subjected to acid phosphatase testing using both direct testing and the 'press test' method. The results showed that semen could be detected in excess of 15 min in dilutions up to 1 in 400 using the press test method and in dilutions up to 1 in 1000 using the direct method. Of further significance was the observation that using the press test method, the two minute cut-off was insufficient to detect the majority of stains and in some cases, semen stains as strong as 1 in 20 dilutions. This research provides compelling evidence for protocols currently utilised in forensic practice to be reviewed in order that forensic scientists do not overlook potential evidential material that may prove suitable for body fluid identification such as DNA STR profiling.

  4. Accuracy of a cut-off value based on the third molar index: Validation in an Australian population.

    PubMed

    Franklin, Daniel; Karkhanis, Shalmira; Flavel, Ambika; Collini, Federica; DeLuca, Stefano; Cameriere, Roberto

    2016-09-01

    According to Recommendation N°196 of the Australian Law Reform Commission (ALRC), the age at which a child reaches adulthood for the purposes of criminal law should be 18 years in all Australian jurisdictions. With specific reference to age at majority, the only tooth with development spanning adolescence (and thus the legally relevant 18 years of age) is the third molar, which limits the number of methods that can be applied from those available in the published literature. The aim of the present study is to test the accuracy of the third molar index (I3M=0.08), based on the correlation between chronological age and normalized measures of the open apices and height of the third mandibular molar, in order to assess the legal adult age of 18 years. Digital orthopantomographs of 143 living Australian subjects (72 boys and 71 girls) are analyzed. The results demonstrate that the sensitivity is 0.90 in boys and 0.90 in girls; associated specificity values are 0.85 and 0.87 respectively. We conclude that the cut-off value of I3M=0.08 is statistically robust and thus valid for forensic application in an Australian population.

  5. Influence of temperature and upper cut-off voltage on the formation of lithium-ion cells

    NASA Astrophysics Data System (ADS)

    German, Florian; Hintennach, Andreas; LaCroix, Annette; Thiemig, Denny; Oswald, Steffen; Scheiba, Frieder; Hoffmann, Michael J.; Ehrenberg, Helmut

    2014-10-01

    The influences of temperature on the formation losses and subsequent electrical performance of Lix(Ni1/3Co1/3Mn1/3)yO2 (NCM)/graphite lithium-ion cells were investigated. It was shown that the total capacity loss during formation of a full cell at 25 °C consists of losses on the positive and negative electrode to about one half each. The losses of the negative electrode (ca. 10%) are due to solid electrolyte interphase (SEI) formation on graphite but are masked by the losses of the positive side (ca. 20%) which are mainly caused by a kinetic inhibition of NCM and are theoretically reversible when the cell is discharged to very low potentials. The total loss of a full cell fits with the loss of the positive electrode. With increased temperature the ratio of losses on positive and negative electrode decreases as the diffusion coefficient of lithium in NCM increases. In total, an elevated formation temperature leads to increased irreversible losses on both electrodes and significantly lower cell performance of graphite. The upper cut-off voltage has an influence on the positive electrode formation losses in a reversible manner. The constituents of the SEI identified via the combination of XPS and FTIR are mainly RCH2OCO2Li, RCOOLi and LiF for the outer SEI and mainly Li2CO3, Li2O and LiF for the inner SEI.

  6. Urinary hepcidin identifies a serum ferritin cut-off for iron supplementation in young athletes: a pilot study.

    PubMed

    Borrione, P; Spaccamiglio, A; Rizzo, M; Termine, A; Chierto, E; Campostrini, N; Quaranta, F; Di Gianfrancesco, A; Pigozzi, F

    2011-01-01

    The use of iron supplements should be a judicious choice, primarily when considering the possible risks deriving from an unjustified treatment. In trained athletes, levels of ferritin between 15 and 30 microg/L are frequently observed. Within this ferritin range, the usefulness of iron supplementation is still controversial. The aim of the present study is to evaluate the clinical usefulness of hepcidin assessment in the analysis of the iron status of young non-anemic athletes. Fifty young athletes were enrolled. The subjects were divided into 4 groups according to their ferritin levels. No statistically significant difference was found regarding hepcidin levels between athletes with ferritin lower than 15 microg/L and those in the 15-30 microg/L range. Similarly, no difference was found between athletes with ferritin higher than 50 microg/L and those in the 30-50 microg/L range. On the contrary, statistically significant differences were found between athletes with ferritin levels ranging from 15 to 30 microg/L and those in the 30-50 microg/L range. The present study suggests that serum ferritin levels below 30 microg/L indicate an asymptomatic iron deficiency status inhibiting hepcidin expression and that 30 microg/L should be considered the ferritin cut-off when considering an iron supplementation in young athletes.

  7. Forecasts of solar and geomagnetic activity

    NASA Technical Reports Server (NTRS)

    Joselyn, Joann

    1987-01-01

    Forecasts of solar and geomagnetic activity are critical since these quantities are such important inputs to the thermospheric density models. At this time in the history of solar science there is no way to make such a forecast from first principles. Physical theory applied to the Sun is developing rapidly, but is still primitive. Techniques used for forecasting depend upon the observations over about 130 years, which is only twelve solar cycles. It has been noted that even-numbered cycles systematically tend to be smaller than the odd-numbered ones by about 20 percent. Another observation is that for the last 12 cycle pairs, an even-numbered sunspot cycle looks rather like the next odd-numbered cycle, but with the top cut off. These observations are examples of approximate periodicities that forecasters try to use to achieve some insight into the nature of an upcoming cycle. Another new and useful forecasting aid is a correlation that has been noted between geomagnetic indices and the size of the next solar cycle. Some best estimates are given concerning both activities.

  8. The Vector Matching Method in Geomagnetic Aiding Navigation.

    PubMed

    Song, Zhongguo; Zhang, Jinsheng; Zhu, Wenqi; Xi, Xiaoli

    2016-07-20

    In this paper, a geomagnetic matching navigation method that utilizes the geomagnetic vector is developed, which can greatly improve the matching probability and positioning precision, even when the geomagnetic entropy information in the matching region is small or the geomagnetic contour line's variety is obscure. The vector iterative closest contour point (VICCP) algorithm that is proposed here has better adaptability with the positioning error characteristics of the inertial navigation system (INS), where the rigid transformation in ordinary ICCP is replaced with affine transformation. In a subsequent step, a geomagnetic vector information fusion algorithm based on Bayesian statistical analysis is introduced into VICCP to improve matching performance further. Simulations based on the actual geomagnetic reference map have been performed for the validation of the proposed algorithm.

  9. The Vector Matching Method in Geomagnetic Aiding Navigation

    PubMed Central

    Song, Zhongguo; Zhang, Jinsheng; Zhu, Wenqi; Xi, Xiaoli

    2016-01-01

    In this paper, a geomagnetic matching navigation method that utilizes the geomagnetic vector is developed, which can greatly improve the matching probability and positioning precision, even when the geomagnetic entropy information in the matching region is small or the geomagnetic contour line’s variety is obscure. The vector iterative closest contour point (VICCP) algorithm that is proposed here has better adaptability with the positioning error characteristics of the inertial navigation system (INS), where the rigid transformation in ordinary ICCP is replaced with affine transformation. In a subsequent step, a geomagnetic vector information fusion algorithm based on Bayesian statistical analysis is introduced into VICCP to improve matching performance further. Simulations based on the actual geomagnetic reference map have been performed for the validation of the proposed algorithm. PMID:27447645

  10. Detectability of small blood vessels with high-frequency power Doppler and selection of wall filter cut-off velocity for microvascular imaging.

    PubMed

    Pinter, Stephen Z; Lacefield, James C

    2009-07-01

    Power Doppler imaging of physiologic and pathologic angiogenesis is widely used in preclinical studies to track normal development, disease progression and treatment efficacy but can be challenging given the presence of small blood vessels and slow flow velocities. Power Doppler images can be plagued with false-positive color pixels or undetected vessels, thereby complicating the interpretation of vascularity metrics such as color pixel density (CPD). As an initial step toward improved microvascular quantification, flow-phantom experiments were performed to establish relationships between vessel detection and various combinations of vessel size (160, 200, 250, 300 and 360 microm), flow velocity (4, 3, 2, 1 and 0.5 mm/s) and transducer frequency (30 and 40 MHz) while varying the wall filter cut-off velocity. Receiver operating characteristic (ROC) curves and areas under ROC curves indicate that good vessel detection performance can be achieved with a 40-MHz transducer for flow velocities > or =2 mm/s and with a 30-MHz transducer for flow velocities > or =1 mm/s. In the second part of the analysis, CPD was plotted as a function of wall filter cut-off velocity for each flow-phantom data set. Three distinct regions were observed: overestimation of CPD at low cut-offs, underestimation of CPD at high cut-offs and a plateau at intermediate cut-offs. The CPD at the plateau closely matched the phantom's vascular volume fraction and the length of the plateau corresponded with the flow-detection performance of the Doppler system assessed using ROC analysis. Color pixel density vs. wall filter cut-off curves from analogous in vivo experiments exhibited the same shape, including a distinct CPD plateau. The similar shape of the flow-phantom and in vivo curves suggests that the presence of a plateau in vivo can be used to identify the best-estimate CPD value that can be treated as a quantitative vascularity metric. The ability to identify the best CPD estimate is expected to

  11. Body composition-derived BMI cut-offs for overweight and obesity in Indians and Creoles of Mauritius: comparison with Caucasians

    PubMed Central

    Hunma, S; Ramuth, H; Miles-Chan, J L; Schutz, Y; Montani, J-P; Joonas, N; Dulloo, A G

    2016-01-01

    Background and Aims: Global estimates of overweight and obesity prevalence are based on the World Health Organisation (WHO) body mass index (BMI) cut-off values of 25 and 30 kg m−2, respectively. To validate these BMI cut-offs for adiposity in the island population of Mauritius, we assessed the relationship between BMI and measured body fat mass in this population according to gender and ethnicity. Methods: In 175 young adult Mauritians (age 20-42 years) belonging to the two main ethnic groups—Indians (South Asian descent) and Creoles (African/Malagasy descent), body weight, height and waist circumference (WC) were measured, total body fat assessed by deuterium oxide (D2O) dilution and trunk (abdominal) fat by segmental bioimpedance analysis. Results: Compared to body fat% predicted from BMI using Caucasian-based equations, body fat% assessed by D2O dilution in Mauritians was higher by 3–5 units in Indian men and women as well as in Creole women, but not in Creole men. This gender-specific ethnic difference in body composition between Indians and Creoles is reflected in their BMI–Fat% relationships, as well as in their WC–Trunk Fat% relationships. Overall, WHO BMI cut-offs of 25 and 30 kg m−2 for overweight and obesity, respectively, seem valid only for Creole men (~24 and 29.5, respectively), but not for Creole women whose BMI cut-offs are 2–4 units lower (21–22 for overweight; 27–28 for obese) nor for Indian men and women whose BMI cut-offs are 3–4 units lower (21–22 for overweight; 26–27 for obese). Conclusions: The use of BMI cut-off points for classifying overweight and obesity need to take into account both ethnicity and gender to avoid gross adiposity status misclassification in this population known to be at high risk for type-2 diabetes and cardiovascular diseases. This is particularly of importance in obesity prevention strategies both in clinical medicine and public health. PMID:27698347

  12. Spectral properties and the effect on redshift cut-off of compact active galactic nuclei from the AT20G survey

    NASA Astrophysics Data System (ADS)

    Chhetri, R.; Ekers, R. D.; Mahony, E. K.; Jones, P. A.; Massardi, M.; Ricci, R.; Sadler, E. M.

    2012-05-01

    Spectral index has been traditionally used to separate extragalactic radio sources into compact and extended populations, with the spectral transition placed variably between -0.4 and -0.6. We use high angular resolution data, measured from visibility of sources at the longest baseline of 4500 m of the Australia Telescope Compact Array (ATCA), for the Australia Telescope 20 GHz (AT20G) survey to obtain angular size information for over 94 per cent of AT20G sources. We confirm the previous AT20G result that due to the high survey frequency of 20 GHz, the source population is strongly dominated by compact sources (79 per cent). At 0.15-arcsec angular resolution limit, we show a very strong correlation between the compact and extended sources with flat and steep-spectrum sources respectively for spectral indices obtained between 1 and 5 GHz. Thus, we provide a firm physical basis for the traditional spectral classification into flat and steep-spectrum sources to select compact and extended sources. We find that for spectral indices between 1 and 5 GHz, the cut-offs at -0.4 and -0.5 are quite similar to the optimum cut-off of -0.46 and, hence, recommend the continued use of -0.5 for future studies. We use the recently published redshift data to study the effect of spectral curvature on the redshift cut-off of compact active galactic nuclei (AGNs). Using spectral indices at different frequencies, we correct for the redshift effect and also produce rest-frame frequency spectra for compact sources for redshifts up to z˜ 5. We show that the spectra of most compact sources are flat to ˜30 GHz and then start to steepen. At higher frequencies, the spectra of both compact and extended sources are steep, so the use of spectral index does not separate the compact and extended source populations as well as in lower frequencies. We also find that due to spectral steepening at high frequencies, surveys of compact sources at higher frequencies (ν > 5 GHz) will have redshift cut-off

  13. Cut-off net acid generation pH in predicting acid-forming potential in mine spoils.

    PubMed

    Liao, B; Huang, L N; Ye, Z H; Lan, C Y; Shu, W S

    2007-01-01

    Acidification of mine wastes can lead to a series of environmental problems, such as acid drainage, heavy metal mobilization, and ecosystem degradation. Prediction of acid-forming potential is one of the key steps in management of sulfide-bearing mine wastes. In this paper, the acid-forming potential of 180 mine waste samples collected from 17 mine sites in China were studied using a net acid generation (NAG) method. The samples contained different contents of total sulfur (ranging from 0.6 to 200 g kg(-1)), pyritic sulfur (ranging from 0 to 100 g kg(-1)), and acid neutralization capacity (ANC, ranging from -41 to 274 kg H2SO4 t(-1)). Samples with high acid-forming potential are generally due to their high sulfur content or low acid neutralization capacity. After the samples were oxidized by H2O2, the amounts of acid generation and the final NAG pH were measured. Results indicated that the final NAG pH gave a well-defined demarcation between acid-forming and non-acid-forming materials. Samples with final NAG pH >or= 5 could be classified as non-acid-forming materials, while those with NAG pH 2.5, but < 5, had low risk of being acid-forming. The confirmation of cut-off NAG pH will be used as a rapid and cost-effective operational monitoring tool for the in-pit prediction of acid-forming potential of mine wastes and classification of waste types.

  14. Impact of oxygen cut off and starvation conditions on biological activity and physico-chemical properties of activated sludge.

    PubMed

    Villain, Maud; Clouzot, Ludiwine; Guibaud, Gilles; Marrot, Benoit

    2013-01-01

    Physico-chemical and biological parameters were monitored both throughout different oxygen cut off and starvation (OCS) times (6 h-72 h) and after the restoration of normal operational conditions. Sludge apparent viscosity and soluble extracellular polymeric substances (EPS) characteristics were measured to determine the activated sludge (AS) properties. Oxygen transfer, biological activity with specific oxygen uptake rate (SOUR) measurements during endogenous/exogenous conditions (without any external substrate/with external substrate consumption) and chemical oxygen demand (COD) removal were measured to assess the AS performances. During the different stress times, AS deflocculated as a decrease of apparent viscosity was observed and microorganisms biodegraded the released EPS to survive. After aeration return, and under endogenous conditions, size exclusion chromatographic fingerprints of soluble EPS were modified and macromolecules probably of type humic-like substances appeared in significant quantities. These new macromolecules presumably acted as biosurfactants. Consequently, the liquid surface tension, as well as the oxygen transfer rate (OTR), decreased. Under exogenous conditions, high biological activity (SOUR = 11.8 +/- 2.1 mg(O2 x g(MLVSS)(-1) x h(-1)) compensated the decrease of oxygen transfer. Finally, AS biomass maintained a constant COD degradation rate (15.7 +/- 1.9 mg(O2) x g(MLVSS)(-1) x h(-1)) before and after the disturbances for all times tested. This work demonstrates that AS microorganisms can counteract concomitant oxygen and nutrients shortage when the duration of such a condition does not exceed 72 h. Dissociation of endogenous/exogenous conditions appears to offer an ideal laboratory model to study EPS and biomass activity effects on oxygen transfer.

  15. Establishing New Cut-Off Limits for Galactose 1-Phosphate-Uridyltransferase Deficiency for the Dutch Newborn Screening Programme.

    PubMed

    Kemper, E A; Boelen, A; Bosch, A M; van Veen-Sijne, M; van Rijswijk, C N; Bouva, M J; Fingerhut, R; Schielen, P C J I

    2017-01-01

    Newborn screening for classical galactosemia in the Netherlands is performed by five laboratories and is based on the measurement of galactose 1-phosphate-uridyltransferase (GALT) activity and total galactose (TGAL) in heel prick blood spots. Unexpected problems with the GALT assay posed a challenge to switch to a new assay. The aim of this study was to make an analytical and clinical evaluation of GALT assays to replace the current assay and to establish new cut-off values (COVs).First, the manual assay from PerkinElmer (NG-1100) and the GSP assay were compared by analyzing 626 anonymous heel prick samples in parallel. Secondly, a manual GSP method was evaluated and 2,052 samples were compared with the automated GSP assay. Finally, a clinical evaluation was performed by collecting data from 93 referred newborns.No satisfactory correlation was observed between GALT activity measured with the manual NG-1100 assay and the automated GSP assay. An acceptable correlation was found between the manual and automated GSP assay. Intra- and inter-assay variation of the automated GSP were 1.8-10.0% and 3.1-13.9%, respectively. Evaluation of clinical data demonstrated that adjusting the COVs for GALT to 2.0 U/dl and TGAL to 1,100 μmol/l improved specificity of screening for classical galactosemia.An assay designed for automated processing to measure GALT activity in heel prick samples works equally well when processed manually. We therefore adopted both methods in the Dutch screening laboratories. As a result of this evaluation new COVs for GALT and TGAL have been introduced and are valid from July 2015.

  16. Combined Effect of an Atmospheric River and a Cut-off Low in Hiroshima Flooding Event on August 19, 2014

    NASA Astrophysics Data System (ADS)

    Takayabu, Y. N.; Hirota, N.; Kato, M.; Arakane, S.

    2015-12-01

    An extraordinary precipitation over 100 mmhr-1in Hiroshima on August 19, 2014, caused a flash flood which resulted in 74 fatalities and collapse of 330 houses. In order to examine the meteorological background of this flooding event, we carried out a detailed analysis utilizing rain gauge data, satellite precipitation dataset, and a meso scale and a global scale objective analyses provided from the Japan Meteorological Agency. Then, we performed numerical experiments using a nonhydrostatic compressible equation model called the Cloud-Resolving Storm Simulator (CReSS). As a result, a combined effect of an atmospheric river (AR) and a cut-off low (COL) in this flooding event was elucidated. During the event, a filamentary transport of moisture extending from the Indochina Peninsula to the Japanese Islands was observed along the southern side of the subtropical jet, forming an AR. This AR had a deep structure with an amount of free tropospheric moisture comparable to that of the boundary layer. Concurrently, there was a COL, detached from the Mid-Pacific Trough, moving northwestward toward the Japanese Archipelago. With various sensitivity experiments, we concluded that a mid-tropospheric instability associated with the cold core of the COL and a dynamical ascent induced in its foreside, collaboratively worked with the anomalous moisture in the free troposphere associated with the AR, to extraordinarily enhance the precipitation over Hiroshima region. An orographic effect to concentrate the precipitation in this region was also confirmed. An implication on a difference in effects of AR in this event with a climatologically moist boundary layer, from those in the US west coast with a very dry environment, was also obtained. Acknowledgment: This study is supported by the Environment Research and Technology Development Fund (2-1503) of the Ministry of the Environment, Japan, and by the Ministry of Education, Culture, Sports, Science and Technology, Japan.

  17. Cut-off values of serum IgE (total and A. fumigatus -specific) and eosinophil count in differentiating allergic bronchopulmonary aspergillosis from asthma.

    PubMed

    Agarwal, Ritesh; Aggarwal, Ashutosh N; Garg, Mandeep; Saikia, Biman; Chakrabarti, Arunaloke

    2014-11-01

    The cut-off values of immunological tests employed in diagnosis of allergic bronchopulmonary aspergillosis (ABPA) have never been validated. Herein, we compare the immunological findings in patients with ABPA and asthma using receiver operating characteristic analysis. Consecutive asthmatic subjects underwent all the following investigations: Aspergillus skin test, IgE levels (total and A. fumigatus-specific), Aspergillus precipitins, eosinophil count, chest radiograph and CT chest. There were 372 subjects (179 men, mean age 35.9 years) with a mean asthma duration of 8 years. ABPA was diagnosed in 76 patients (64 bronchiectasis, 12 without bronchiectasis). ABPA was separated from asthma using the best cut-off values of total IgE, A. fumigatus IgE and total eosinophil count of 2347 IU ml(-1) , 1.91 kUA l(-1) and 507 cells per μl respectively. The sensitivity/specificity of these parameters were 87/81%; 99/87%; and, 79/76% respectively. The corresponding AUC values were 0.95, 0.90 and 0.82 respectively. The combination of these three tests at the aforementioned cut-offs provided 100% specificity. Our study provides evidence-based cut-off values of IgE (total and A. fumigatus-specific) and eosinophil counts in differentiating ABPA from asthma. As this is a single centre retrospective study, further studies from different centres are required, as these values could vary by ethnicity and environmental exposure.

  18. The impact of lowering the cut-off value on the sensitivity of the Platelia Elisa IgG (Bio-Rad) test for toxoplasmosis diagnosis

    PubMed Central

    Mouri, Oussama; Kendjo, Eric; Touafek, Feriel; Fekkar, Arnaud; Konte, Ousmane; Imbert, Sebastien; Courtin, Régis; Mazier, Dominique; Paris, Luc

    2015-01-01

    Determining specific immune status against Toxoplasma gondii is essential for assessing the risk of reactivation in immunocompromised patients or defining serological monitoring and appropriate prophylactic measures during pregnancy. In France, toxoplasmosis serological screening requires systematic testing for IgM and IgG antibodies. The Platelia Toxo IgG and IgM test (Bio-Rad) is one of the most widely used tests for anti-toxoplasmic antibody detection. We performed a study on 384 sera, including 123 IgG negative (<6 IU/mL) and 261 IgG equivocal (6–9 IU/mL) sera tested with Platelia Toxo IgG and collected during routine screening at Pitié-Salpêtrière Hospital, Paris, France to determine the best-performing IgG titer cut-off value. Out of these 383 sera, 298 were IgM negative by Platelia Toxo IgM and 86 were IgM positive. All sera were also tested against Toxo IgG II LD BIO western blot test as confirmation. Our results indicated that an IgG titer cut-off value of ≥4.4 IU/mL for the Platelia Toxo IgG met the definition of positivity, a value significantly lower than that indicated by the manufacturers. In the presence of IgM antibodies, the IgG titer cut-off decreased significantly to a value ≥0.2 IU/mL. This latter cut-off also allowed adequate diagnosis of proven toxoplasmosis seroconversion in 76.7% of cases (33/43). Our findings may improve toxoplasmosis care by reducing therapeutic intervention time and eliminating the need for further serological monitoring. PMID:26187780

  19. Cut-off points for mild, moderate, and severe pain on the visual analogue scale for pain in patients with chronic musculoskeletal pain.

    PubMed

    Boonstra, Anne M; Schiphorst Preuper, Henrica R; Balk, Gerlof A; Stewart, Roy E

    2014-12-01

    The aim of this study was to find the cut-off points on the visual analogue scale (VAS) to distinguish among mild, moderate, and severe pain, in relation to the following: pain-related interference with functioning; verbal description of the VAS scores; and latent class analysis for patients with chronic musculoskeletal pain. A total of 456 patients were included. Pain was assessed using the VAS and verbal rating scale; functioning was assessed using the domains of the Short Form (36) Health Survey (SF-36). Eight cut-off point schemes were tested using multivariate analysis of variance (MANOVA), ordinal logistic regression, and latent class analysis. The study results showed that VAS scores ⩽ 3.4 corresponded to mild interference with functioning, whereas 3.5 to 6.4 implied moderate interference, and ⩾ 6.5 implied severe interference. VAS scores ⩽ 3.4 were best described for patients with chronic musculoskeletal pain as mild pain, 3.5 to 7.4 as moderate pain, and ⩾ 7.5 as severe pain. Latent class analysis found that a 3-class solution fitted best, resulting in the classes 0.1 to 3.8, 3.9 to 5.7, and 5.8 to 10 cm. Findings from our study agree with those of some other studies, although many other studies found different optimal cut-off point schemes. As there appear to be no universally accepted cut-off points, and in view of the low-to-moderate associations between VAS scores and functioning and between VAS and verbal rating scale scores, the correct classification of VAS scores as mild, moderate. or severe in clinical practice seems doubtful.

  20. Cerebrospinal Fluid Neopterin Analysis in Neuropediatric Patients: Establishment of a New Cut Off-Value for the Identification of Inflammatory-Immune Mediated Processes

    PubMed Central

    Molero-Luis, Marta; Fernández-Ureña, Sergio; Jordán, Iolanda; Serrano, Mercedes; Ormazábal, Aida; Garcia-Cazorla, Àngels; Artuch, Rafael

    2013-01-01

    Objective A high level of cerebrospinal fluid (CSF) neopterin is a marker of central nervous system inflammatory-immune mediated processes. We aimed to assess data from 606 neuropediatric patients, describing the clinical and biochemical features of those neurological disorders presenting CSF neopterin values above a new cut-off value that was defined in our laboratory. Methods To establish the new CSF neopterin cut-off value, we studied two groups of patients: Group 1 comprised 68 patients with meningoencephalitis, and Group 2 comprised 52 children with a confirmed peripheral infection and no central nervous system involvement. We studied 606 CSF samples from neuropediatric patients who were classified into 3 groups: genetic diagnosis (A), acquired/unknown etiologic neurologic diseases (B) and inflammatory-immune mediated processes (C). Results The CSF neopterin cut-off value was 61 nmol/L. Out of 606 cases, 56 presented a CSF neopterin level above this value. Group C had significantly higher CSF neopterin, protein and leukocyte values than the other groups. Sixteen of twenty-three patients in this group had a CSF neopterin level above the cut-off, whereas three and seven patients presented increased leukocyte and protein values, respectively. A significant association was found among CSF neopterin, proteins and leukocytes in the 606 patients. White matter disturbances were associated with high CSF neopterin concentrations. Conclusions Although children with inflammatory-immune mediated processes presented higher CSF neopterin values, patients with other neurological disorders also showed increased CSF neopterin concentrations. These results stress the importance of CSF neopterin analysis for the identification of inflammatory-immune mediated processes. PMID:24367586

  1. Return to Work: A Cut-Off of FIM Gain with Montebello Rehabilitation Factor Score in Order to Identify Predictive Factors in Subjects with Acquired Brain Injury

    PubMed Central

    2016-01-01

    Return to work (RTW) for people with acquired brain injury (ABI) represents a main objective of rehabilitation: this work presents a strong correlation between personal well-being and quality of life. The aim of this study is to investigate the prognostic factors that can predict RTW after ABI (traumatic or non- traumatic aetiology) in patients without disorders of consciousness (e.g. coma, vegetative or minimally conscious state) at the beginning of their admission to rehabilitation. At the end of a 6-month follow-up after discharge, data were successfully collected in 69 patients. The rehabilitation effectiveness (functional Recovery) between admission and discharge was assessed by Functional Independent Measure (FIM) gain, through the Montebello Rehabilitation Factor Score (MRFS), which was obtained as follows: (discharge FIM—admission FIM)/(Maximum possible FIM—Admission FIM) x 100. The cut-off value (criterion) deriving from MRFS, which helped identify RTW patients, resulted in .659 (sn 88.9%; sp 52.4%). Considering the Mini Mental State Examination (MMSE) and the MRFS data, the multivariable binary logistic regression analysis presented 62.96% of correct RTW classification cases, 80.95% of non-RTW leading to an overall satisfactory predictability of 73.91%. The results of the present study suggest that occupational therapy intervention could modify cut-off in patients with an MFRS close to target at the end of an in-hospital rehabilitative program thus developing their capabilities and consequently surpassing cut-off itself. PMID:27780215

  2. Return to Work: A Cut-Off of FIM Gain with Montebello Rehabilitation Factor Score in Order to Identify Predictive Factors in Subjects with Acquired Brain Injury.

    PubMed

    Franceschini, Marco; Massimiani, Maria Pia; Paravati, Stefano; Agosti, Maurizio

    2016-01-01

    Return to work (RTW) for people with acquired brain injury (ABI) represents a main objective of rehabilitation: this work presents a strong correlation between personal well-being and quality of life. The aim of this study is to investigate the prognostic factors that can predict RTW after ABI (traumatic or non- traumatic aetiology) in patients without disorders of consciousness (e.g. coma, vegetative or minimally conscious state) at the beginning of their admission to rehabilitation. At the end of a 6-month follow-up after discharge, data were successfully collected in 69 patients. The rehabilitation effectiveness (functional Recovery) between admission and discharge was assessed by Functional Independent Measure (FIM) gain, through the Montebello Rehabilitation Factor Score (MRFS), which was obtained as follows: (discharge FIM-admission FIM)/(Maximum possible FIM-Admission FIM) x 100. The cut-off value (criterion) deriving from MRFS, which helped identify RTW patients, resulted in .659 (sn 88.9%; sp 52.4%). Considering the Mini Mental State Examination (MMSE) and the MRFS data, the multivariable binary logistic regression analysis presented 62.96% of correct RTW classification cases, 80.95% of non-RTW leading to an overall satisfactory predictability of 73.91%. The results of the present study suggest that occupational therapy intervention could modify cut-off in patients with an MFRS close to target at the end of an in-hospital rehabilitative program thus developing their capabilities and consequently surpassing cut-off itself.

  3. Optimal Elasticity cut-off value for discriminating Healthy to Pathological Fibrotic patients employing Fuzzy C-Means automatic segmentation in Liver Shear Wave Elastography images

    NASA Astrophysics Data System (ADS)

    Gatos, Ilias; Tsantis, Stavros; Skouroliakou, Aikaterini; Theotokas, Ioannis; Zoumpoulis, Pavlos S.; Kagadis, George C.

    2015-09-01

    The aim of the present study is to determine an optimal elasticity cut-off value for discriminating Healthy from Pathological fibrotic patients by means of Fuzzy C-Means automatic segmentation and maximum participation cluster mean value employment in Shear Wave Elastography (SWE) images. The clinical dataset comprised 32 subjects (16 Healthy and 16 histological or Fibroscan verified Chronic Liver Disease). An experienced Radiologist performed SWE measurement placing a region of interest (ROI) on each subject's right liver lobe providing a SWE image for each patient. Subsequently Fuzzy C-Means clustering was performed on every SWE image utilizing 5 clusters. Mean Stiffness value and pixels number of each cluster were calculated. The mean stiffness value feature of the cluster with maximum pixels number was then fed as input for ROC analysis. The selected Mean Stiffness value feature an Area Under the Curve (AUC) of 0.8633 with Optimum Cut-off value of 7.5 kPa with sensitivity and specificity values of 0.8438 and 0.875 and balanced accuracy of 0.8594. Examiner's classification measurements exhibited sensitivity, specificity and balanced accuracy value of 0.8125 with 7.1 kPa cutoff value. A new promising automatic algorithm was implemented with more objective criteria of defining optimum elasticity cut-off values for discriminating fibrosis stages for SWE. More subjects are needed in order to define if this algorithm is an objective tool to outperform manual ROI selection.

  4. Prevalence of body mass index and body weight cut-off points for in vitro fertilization treatment at U.S. clinics and current clinic weight loss strategy recommendations.

    PubMed

    Turner-McGrievy, Gabrielle M; Grant, Breănna L

    2015-09-01

    The goal of this study was to determine how many clinics providing in vitro fertilization (IVF) in the United States require a body mass index (BMI) or body weight cut-off point to determine treatment eligibility. US clinics listed as members on the Society of Assisted Reproduction website in late 2013 were contacted by phone between January and March 2014. Clinic personnel were asked if a BMI or body weight cut-off points was used to determine IVF treatment eligibility and what strategies they recommended for their patients to achieve a healthy body weight. Of the 379 clinics contacted, 347 responded (92% response rate) and 35% (n = 120) reported using a BMI or body weight cut-off points to determine eligibility for IVF treatment. Mean BMI (± SD) cut-off points was 38.4 ± 5.2 kg/m(2) and mean body weight (± SD) cut-off points was 130.2 ± 14.8 kg. Of the clinics using a set cut-off points, half (46%) provided no weight loss recommendations for patients. A sizable portion of US IVF clinics report a required or preferred BMI or body weight cut-off points for treatment. Despite this, most clinics did not provide a recommended program or approach for weight loss with very few clinics reporting an in-house program.

  5. Endogenous gamma-hydroxybutyric acid (GHB) concentrations in post-mortem specimens and further recommendation for interpretative cut-offs.

    PubMed

    Andresen-Streichert, Hilke; Jensen, P; Kietzerow, J; Schrot, M; Wilke, N; Vettorazzi, E; Mueller, A; Iwersen-Bergmann, S

    2015-01-01

    When interpreting gamma-hydroxybutyric acid (GHB) concentrations in post-mortem specimens, a possible increase in GHB concentrations because of post-mortem generation must be considered. In this study, endogenous GHB concentrations in post-mortem biological fluids were investigated. Additionally, we review post-mortem GHB concentrations already published in the literature. Heart and peripheral blood samples, cerebrospinal fluid, urine, and vitreous humor were collected from 64 autopsies in subjects where the cause of death excluded GHB exposure. Sample analysis was carried out either on the day of autopsy or later after immediate freezing and storage at -20 °C. GHB concentrations in venous blood samples (n = 61) were <0.6-28.7 mg/L (mean 11.9 mg/L; median 10.6 mg/L), <0.6-65.3 mg/L (mean 15.2 mg/L; median 12.8 mg/L) in heart blood (n = 56), <0.6-25.1 mg/L (mean 6.0 mg/L; median 3.8 mg/L) in urine (n = 50), <0.6-39.0 mg/L (mean 9.6 mg/L; median 7.5 mg/L), in vitreous humor (n = 54), and <0.6-24.0 mg/L (mean 4.2 mg/L; median 3.2 mg/L) in cerebrospinal fluid (n = 52). There was no significant difference between GHB concentrations in cases where there were signs of beginning putrefaction at the time of autopsy (n = 9) and cases without obvious signs of putrefaction. In one case with advanced putrefaction, the GHB concentration in venous blood was 32.7 mg/L. In conclusion, for post-mortem venous blood, urine, and cerebrospinal fluid, an interpretative cut-off of 30 mg/L for GHB concentrations is suggested in cases where GHB analysis is conducted on the day of sample collection at autopsy or if samples have been stored at -20 °C immediately after collection.

  6. Medium Cut-Off (MCO) Membranes Reduce Inflammation in Chronic Dialysis Patients—A Randomized Controlled Clinical Trial

    PubMed Central

    Zickler, Daniel; Schindler, Ralf; Willy, Kevin; Martus, Peter; Pawlak, Michael; Storr, Markus; Hulko, Michael; Boehler, Torsten; Glomb, Marcus A.; Liehr, Kristin; Henning, Christian; Templin, Markus; Trojanowicz, Bogusz; Ulrich, Christof; Werner, Kristin; Fiedler, Roman; Girndt, Matthias

    2017-01-01

    Background To increase the removal of middle-sized uremic toxins a new membrane with enhanced permeability and selectivity, called Medium Cut-Off membrane (MCO-Ci) has been developed that at the same time ensures the retention of albumin. Because many middle-sized substances may contribute to micro-inflammation we hypothesized that the use of MCO-Ci influences the inflammatory state in hemodialysis patients. Methods The randomized crossover trial in 48 patients compared MCO-Ci dialysis to High-flux dialysis of 4 weeks duration each plus 8 weeks extension phase. Primary endpoint was the gene expression of TNF-α and IL-6 in peripheral blood mononuclear cells (PBMCs), secondary endpoints were plasma levels of specified inflammatory mediators and cytokines. Results After four weeks of MCO-Ci the expression of TNF-α mRNA (Relative quantification (RQ) from 0.92 ± 0.34 to 0.75 ± 0.31, -18.5%, p<0.001)-α and IL-6 mRNA (RQ from 0.78 ± 0.80 to 0.60 ± 0.43, -23.1%, p<0.01) was reduced to a significantly greater extent than with High-flux dialyzers (TNF mRNA-RQ: -14.3%; IL-6 mRNA-RQ: -3.5%). After retransformation of logarithmically transformed data, measurements after MCO were reduced to 82% of those after HF (95% CI 74%–91%). 4 weeks use of MCO-Ci resulted in long-lasting change in plasma levels of several cytokines and other substances with a significant decrease for sTNFR1, kappa and lambda free light chains, urea and an increase for Lp-PLA2 (PLA2G7) compared to High-flux. Albumin levels dropped significantly after 4 weeks of MCO dialysis but increased after additional 8 weeks of MCO dialysis. Twelve weeks treatment with MCO-Ci was well tolerated regarding the number of (S)AEs. In the extension period levels of CRP, TNF-α-mRNA and IL-6 mRNA remained stable in High-flux as well as in MCO-Ci. Conclusions MCO-Ci dialyzers modulate inflammation in chronic HD patients to a greater extent compared to High-flux dialyzers. Transcription of pro-inflammatory cytokines in

  7. Effect of Accelerometer Cut-Off Points on the Recommended Level of Physical Activity for Obesity Prevention in Children

    PubMed Central

    Dygrýn, Jan; Mitáš, Josef; Jakubec, Lukáš; Frömel, Karel

    2016-01-01

    There is no general consensus regarding which accelerometer cut-off point (CoP) is most acceptable to estimate the time spent in moderate-to-vigorous physical activity (MVPA) in children and choice of an appropriate CoP primarily remains a subjective decision. Therefore, this study aimed to analyze the influence of CoP selection on the mean MVPA and to define the optimal thresholds of MVPA derived from different accelerometer CoPs to avoid overweight/obesity and adiposity in children aged 7 to 12 years. Three hundred six children participated. Physical activity (PA) was monitored for seven consecutive days using an ActiGraph accelerometer (model GT3X) and the intensity of PA was estimated using the five most frequently published CoPs. Body adiposity was assessed using a multi-frequency bioelectrical impedance analysis. There was found a wide range of mean levels of MVPA that ranged from 27 (Puyau CoP) to 231 min∙d–1 (Freedson 2005 CoP). A receiver operating characteristic curve analysis indicated that the optimal thresholds for counts per minute (cpm) and MVPA derived from the Puyau CoP was the most useful in classifying children according to their body mass index (BMI) and fat mass percentage (FM%). In the total sample, the optimal thresholds of the MVPA derived from the Puyau CoP were 22 and 23 min∙d–1 when the categories based on BMI and FM%, respectively, were used. The children who did not meet these optimal thresholds had a significantly increased risk of being overweight/obese (OR = 2.88, P < 0.01) and risk of having excess fat mass (OR = 2.41, P < 0.01). In conclusion, the decision of selecting among various CoPs significantly influences the optimal levels of MVPA. The Puyau CoP of 3 200 cmp seems to be the most useful for defining the optimal level of PA for pediatric obesity prevention. PMID:27723835

  8. Further performance evaluation of 5.3 μm cut-off Hawaii-2RG detectors

    NASA Astrophysics Data System (ADS)

    Ives, Derek; Beckmann, Udo; Alvarez, Domingo; Finger, Gert; Geimer, Christoph; Heininger, Matthias; Mehrgan, Leander; Tulloch, Simon

    2016-07-01

    ESO has now delivered or tested in-house, four new 5.3 μm cut-off H2RG detectors, for various projects, such as MATISSE for the VLTI and the upgrade project for CRIRES, the cryogenic high-resolution infrared echelle spectrograph for the VLT. The specified instruments have required the implementation of some of the more unusual read out options for these detectors, which may have already been used by other groups, for example, the line-reset-read and line-read-reset modes rather than the standard global reset mode. The detectors are also offered with both output speed options, that is, the standard slow, low noise readout and the faster, higher noise readout, where > 10 frames/s are possible. In the process of building these detector systems and implementing these new options we have delved deeper into some of the lesser known features of these detectors and tried to characterize them more fully. It is important that these characteristics are well understood before delivery of the next generation of detectors for the ELTs where high speed and windowing options are required. We obtain very good performance at 2 Mpixel/s pixel speeds with less than 40 e- rms read noise, in all other aspects such as linearity, noise versus number of non-destructive reads and cross talk then the performance of the outputs is the same as slow speed operation. However, the high speed output stages are quite complex to operate, they need to be very well tuned and are prone to oscillation, if not set correctly. We will report on the best bias options to optimize their performance. Some stability issues are also seen with the slow outputs and this is also reported. Likewise we have observed differences between global reset and line reset for the detectors, manifested in a significant increase in detector full well for the line reset option, this also will be reported on. We have also determined that there may be signal induced by the detector readout clocking process for certain detector

  9. Fatty acid ethyl esters in hair as alcohol markers: estimating a reliable cut-off point by evaluation of 1,057 autopsy cases.

    PubMed

    Hastedt, Martin; Bossers, Lydia; Krumbiegel, Franziska; Herre, Sieglinde; Hartwig, Sven

    2013-06-01

    Alcohol abuse is a widespread problem, especially in Western countries. Therefore, it is important to have markers of alcohol consumption with validated cut-off points. For many years research has focused on analysis of hair for alcohol markers, but data on the performance and reliability of cut-off values are still lacking. Evaluating 1,057 cases from 2005 to 2011, included a large sample group for the estimation of an applicable cut-off value when compared to earlier studies on fatty acid ethyl esters (FAEEs) in hair. The FAEEs concentrations in hair, police investigation reports, medical history, and the macroscopic and microscopic alcohol-typical results from autopsy, such as liver, pancreas, and cardiac findings, were taken into account in this study. In 80.2 % of all 1,057 cases pathologic findings that may be related to alcohol abuse were reported. The cases were divided into social drinkers (n = 168), alcohol abusers (n = 502), and cases without information on alcohol use. The median FAEEs concentration in the group of social drinkers was 0.302 ng/mg (range 0.008-14.3 ng/mg). In the group of alcohol abusers a median of 1.346 ng/mg (range 0.010-83.7 ng/mg) was found. Before June 2009 the hair FAEEs test was routinely applied to a proximal hair segment of 0-6 cm, changing to a routinely investigated hair length of 3 cm after 2009, as proposed by the Society of Hair Testing (SoHT). The method showed significant differences between the groups of social drinkers and alcoholics, leading to an improvement in the postmortem detection of alcohol abuse. Nevertheless, the performance of the method was rather poor, with an area under the curve calculated from receiver operating characteristic (ROC curve AUC) of 0.745. The optimum cut-off value for differentiation between social and chronic excessive drinking calculated for hair FAEEs was 1.08 ng/mg, with a sensitivity of 56 % and a specificity of 80 %. In relation to the "Consensus on Alcohol Markers 2012

  10. Validation of two age dependent D-dimer cut-off values for exclusion of deep vein thrombosis in suspected elderly patients in primary care: retrospective, cross sectional, diagnostic analysis

    PubMed Central

    Koek, H L (Dineke); Oudega, Ruud; Geersing, Geert-Jan; Janssen, Kristel J M; van Delden, Johannes J M; Moons, Karel G M

    2012-01-01

    Objective To determine whether the use of age adapted D-dimer cut-off values can be translated to primary care patients who are suspected of deep vein thrombosis. Design Retrospective, cross sectional diagnostic study. Setting 110 primary care doctors affiliated with three hospitals in the Netherlands. Participants 1374 consecutive patients (936 (68.1%) aged >50 years) with clinically suspected deep vein thrombosis. Main outcome measures Proportion of patients with D-dimer values below two proposed age adapted cut-off levels (age in years×10 μg/L in patients aged >50 years, or 750 μg/L in patients aged ≥60 years), in whom deep vein thrombosis could be excluded; and the number of false negative results. Results Using the Wells score, 647 patients had an unlikely clinical probability of deep vein thrombosis. In these patients (at all ages), deep vein thrombosis could be excluded in 309 (47.8%) using the age dependent cut-off value compared with 272 (42.0%) using the conventional cut-off value of 500 μg/L (increase 5.7%, 95% confidence interval 4.1% to 7.8%). This exclusion rate resulted in 0.5% and 0.3% false negative cases, respectively (increase 0.2%, 0.004% to 8.6%).The increase in exclusion rate by using the age dependent cut-off value was highest in the oldest patients. In patients older than 80 years, deep vein thrombosis could be safely excluded in 22 (35.5%) patients using the age dependent cut-off value compared with 13 (21.0%) using the conventional cut-off value (increase 14.5%, 6.8% to 25.8%). Compared with the age dependent cut-off value, the cut-off value of 750 μg/L had a similar exclusion rate (307 (47.4%) patients) and false negative rate (0.3%). Conclusions Combined with a low clinical probability of deep vein thrombosis, use of the age dependent D-dimer cut-off value for patients older than 50 years or the cut-off value of 750 μg/L for patients aged 60 years and older resulted in a considerable increase in the proportion of patients in

  11. The Use of Innovative Two-Component Cluster Analysis and Serodiagnostic Cut-Off Methods to Estimate Prevalence of Pertussis Reinfections

    PubMed Central

    van Twillert, Inonge; Bonačić Marinović, Axel A.; van Gaans-van den Brink, Jacqueline A. M.; Kuipers, Betsy; Berbers, Guy A. M.; van der Maas, Nicoline A. T.; Verheij, Theo J. M.; Versteegh, Florens G. A.; Teunis, Peter F. M.; van Els, Cécile A. C. M.

    2016-01-01

    Bordetella pertussis circulates even in highly vaccinated countries affecting all age groups. Insight into the scale of concealed reinfections is important as they may contribute to transmission. We therefore investigated whether current single-point serodiagnostic methods are suitable to estimate the prevalence of pertussis reinfection. Two methods based on IgG-Ptx plasma levels alone were used to evaluate the proportion of renewed seroconversions in the past year in a cohort of retrospective pertussis cases ≥ 24 months after a proven earlier symptomatic infection. A Dutch population database was used as a baseline. Applying a classical 62.5 IU/ml IgG-Ptx cut-off, we calculated a seroprevalence of 15% in retrospective cases, higher than the 10% observed in the population baseline. However, this method could not discriminate between renewed seroconversion and waning of previously infection-enhanced IgG-Ptx levels. Two-component cluster analysis of the IgG-Ptx datasets of both pertussis cases and the general population revealed a continuum of intermediate IgG-Ptx levels, preventing the establishment of a positive population and the comparison of prevalence by this alternative method. Next, we investigated the complementary serodiagnostic value of IgA-Ptx levels. When modelling datasets including both convalescent and retrospective cases we obtained new cut-offs for both IgG-Ptx and IgA-Ptx that were optimized to evaluate renewed seroconversions in the ex-cases target population. Combining these cut-offs two-dimensionally, we calculated 8.0% reinfections in retrospective cases, being below the baseline seroprevalence. Our study for the first time revealed the shortcomings of using only IgG-Ptx data in conventional serodiagnostic methods to determine pertussis reinfections. Improved results can be obtained with two-dimensional serodiagnostic profiling. The proportion of reinfections thus established suggests a relatively increased period of protection to renewed

  12. The Use of Innovative Two-Component Cluster Analysis and Serodiagnostic Cut-Off Methods to Estimate Prevalence of Pertussis Reinfections.

    PubMed

    van Twillert, Inonge; Bonačić Marinović, Axel A; van Gaans-van den Brink, Jacqueline A M; Kuipers, Betsy; Berbers, Guy A M; van der Maas, Nicoline A T; Verheij, Theo J M; Versteegh, Florens G A; Teunis, Peter F M; van Els, Cécile A C M

    2016-01-01

    Bordetella pertussis circulates even in highly vaccinated countries affecting all age groups. Insight into the scale of concealed reinfections is important as they may contribute to transmission. We therefore investigated whether current single-point serodiagnostic methods are suitable to estimate the prevalence of pertussis reinfection. Two methods based on IgG-Ptx plasma levels alone were used to evaluate the proportion of renewed seroconversions in the past year in a cohort of retrospective pertussis cases ≥ 24 months after a proven earlier symptomatic infection. A Dutch population database was used as a baseline. Applying a classical 62.5 IU/ml IgG-Ptx cut-off, we calculated a seroprevalence of 15% in retrospective cases, higher than the 10% observed in the population baseline. However, this method could not discriminate between renewed seroconversion and waning of previously infection-enhanced IgG-Ptx levels. Two-component cluster analysis of the IgG-Ptx datasets of both pertussis cases and the general population revealed a continuum of intermediate IgG-Ptx levels, preventing the establishment of a positive population and the comparison of prevalence by this alternative method. Next, we investigated the complementary serodiagnostic value of IgA-Ptx levels. When modelling datasets including both convalescent and retrospective cases we obtained new cut-offs for both IgG-Ptx and IgA-Ptx that were optimized to evaluate renewed seroconversions in the ex-cases target population. Combining these cut-offs two-dimensionally, we calculated 8.0% reinfections in retrospective cases, being below the baseline seroprevalence. Our study for the first time revealed the shortcomings of using only IgG-Ptx data in conventional serodiagnostic methods to determine pertussis reinfections. Improved results can be obtained with two-dimensional serodiagnostic profiling. The proportion of reinfections thus established suggests a relatively increased period of protection to renewed

  13. Usefulness of the CAPE-P15 for detecting people at ultra-high risk for psychosis: Psychometric properties and cut-off values.

    PubMed

    Bukenaite, Akvile; Stochl, Jan; Mossaheb, Nilufar; Schäfer, Miriam R; Klier, Claudia M; Becker, Jana; Schloegelhofer, Monika; Papageorgiou, Konstantinos; Montejo, Angel L; Russo, Debra A; Jones, Peter B; Perez, Jesus; Amminger, G Paul

    2017-02-26

    A need for a brief, easy to complete self-report questionnaire to detect people at ultra-high risk for psychosis (UHR) in busy clinical settings has been recognised. Our aim was to explore whether the Community Assessment of Psychic Experiences - Positive 15-items Scale (CAPE-P15) could be used as a screening tool to identify people at UHR in a clinical setting. Our objectives were to confirm the CAPE-P15 factorial structure as well as its reliability and determine cut-off values for the detection of such individuals using the Comprehensive Assessment of At-Risk Mental States (CAARMS), a commonly used clinical interview for the detection of UHR. 165 participants aged between 13 and 18 referred to the General Hospital of Vienna were included in the analysis. 50.9% of the sample were "CAARMS-positive" and 49.1% "CAARMS-negative". The Youden method determined CAPE-P15 cut-off values for UHR detection of 1.47 for both frequency of and distress associated with psychotic experiences. The cut-off value of 1.47 for frequency showed sensitivity of 77%, specificity of 58%, a positive predictive value of 66% and a negative predictive value of 71%; whilst for distress it showed sensitivity of 73%, specificity of 63%, a positive predictive value of 69% and a negative predictive value of 66%. Good reliability and the previously suggested three-correlated factor model as well as an alternative bi-factor model of the CAPE-P15 were confirmed. The CAPE-P15 seems to be a promising screening tool for identifying people who might be at UHR in busy clinical settings.

  14. Using a 3% Proton Density Fat Fraction as a Cut-off Value Increases Sensitivity of Detection of Hepatic Steatosis, Based on Results from Histopathology Analysis.

    PubMed

    Nasr, Patrik; Forsgren, Mikael F; Ignatova, Simone; Dahlström, Nils; Cedersund, Gunnar; Leinhard, Olof Dahlqvist; Norén, Bengt; Ekstedt, Mattias; Lundberg, Peter; Kechagias, Stergios

    2017-03-09

    It is possible to estimate hepatic triglyceride content by calculating the proton density fat fraction (PDFF), using proton magnetic resonance spectroscopy ((1)H-MRS), instead of collecting and analyzing liver biopsies to detect steatosis. However, the current PDFF cut-off value (5%) used to define steatosis by magnetic resonance was derived from studies that did not use histopathology as the reference standard. We performed a prospective study to determine the accuracy of (1)H-MRS PDFF in measurement of steatosis using histopathology analysis as the standard. We collected clinical, serologic, (1)H-MRS PDFF, and liver biopsy data from 94 adult patients with increased levels of liver enzymes (6 months or more) referred to the Department of Gastroenterology and Hepatology at Linköping University Hospital in Sweden from 2007 through 2014. Steatosis was graded using the conventional histopathology method and fat content was quantified in biopsy samples using stereological point counts (SPCs). We correlated (1)H-MRS PDFF findings with SPCs (r = 0.92; P <.001). (1)H-MRS PDFF results correlated with histopathology results (ρ = 0.87; P <.001), and SPCs correlated with histopathology results (ρ = 0.88; P <.001). All 25 subjects with PDFF values of 5.0% or more had steatosis based on histopathology findings (100% specificity for PDFF). However, of 69 subjects with PDFF values below 5.0% (negative result), 22 were determined to have steatosis based on histopathology findings (53% sensitivity for PDFF). Reducing the PDFF cut-off value to 3.0% identified patients with steatosis with 100% specificity and 79% sensitivity; a PDFF cut-off value of 2.0% identified patients with steatosis with 94% specificity and 87% sensitivity. These findings might be used to improve non-invasive detection of steatosis.

  15. Insulin resistance (HOMA-IR) cut-off values and the metabolic syndrome in a general adult population: effect of gender and age: EPIRCE cross-sectional study

    PubMed Central

    2013-01-01

    Background Insulin resistance has been associated with metabolic and hemodynamic alterations and higher cardio metabolic risk. There is great variability in the threshold homeostasis model assessment of insulin resistance (HOMA-IR) levels to define insulin resistance. The purpose of this study was to describe the influence of age and gender in the estimation of HOMA-IR optimal cut-off values to identify subjects with higher cardio metabolic risk in a general adult population. Methods It included 2459 adults (range 20–92 years, 58.4% women) in a random Spanish population sample. As an accurate indicator of cardio metabolic risk, Metabolic Syndrome (MetS), both by International Diabetes Federation criteria and by Adult Treatment Panel III criteria, were used. The effect of age was analyzed in individuals with and without diabetes mellitus separately. ROC regression methodology was used to evaluate the effect of age on HOMA-IR performance in classifying cardio metabolic risk. Results In Spanish population the threshold value of HOMA-IR drops from 3.46 using 90th percentile criteria to 2.05 taking into account of MetS components. In non-diabetic women, but no in men, we found a significant non-linear effect of age on the accuracy of HOMA-IR. In non-diabetic men, the cut-off values were 1.85. All values are between 70th-75th percentiles of HOMA-IR levels in adult Spanish population. Conclusions The consideration of the cardio metabolic risk to establish the cut-off points of HOMA-IR, to define insulin resistance instead of using a percentile of the population distribution, would increase its clinical utility in identifying those patients in whom the presence of multiple metabolic risk factors imparts an increased metabolic and cardiovascular risk. The threshold levels must be modified by age in non-diabetic women. PMID:24131857

  16. Energy-averaged electron-ion momentum transport cross section in the Born approximation and Debye-Hückel potential: Comparison with the cut-off theory

    NASA Astrophysics Data System (ADS)

    Zaghloul, Mofreh R.; Bourham, Mohamed A.; Doster, J. Michael

    2000-04-01

    An exact analytical expression for the energy-averaged electron-ion momentum transport cross section in the Born approximation and Debye-Hückel exponentially screened potential has been derived and compared with the formulae given by other authors. A quantitative comparison between cut-off theory and quantum mechanical perturbation theory has been presented. Based on results from the Born approximation and Spitzer's formula, a new approximate formula for the quantum Coulomb logarithm has been derived and shown to be more accurate than previous expressions.

  17. Energy-averaged electron-ion momentum transport cross section in the Born Approximation and Debye-Hückel potential: Comparison with the cut-off theory

    NASA Astrophysics Data System (ADS)

    Zaghloul, Mofreh R.; Bourham, Mohamed A.; Doster, J. Michael

    2000-02-01

    An exact analytical expression for the energy-averaged electron-ion momentum transport cross section in the Born approximation and Debye-Hückel exponentially screened potential has been derived and compared with the formulae given by other authors. A quantitative comparison between cut-off theory and quantum mechanical perturbation theory has been presented. Based on results from the Born approximation and Spitzer's formula, a new approximate formula for the quantum Coulomb logarithm has been derived and shown to be more accurate than previous expressions.

  18. A preliminary evaluation of the occurrence and characteristics of cut-off ponds of the Maryland shores of the Chesapeake Bay

    SciTech Connect

    Not Available

    1980-10-01

    Under the auspices of the Maryland Power Plant Siting Program, a preliminary investigation of occurrence and characteristics of cut-off ponds in the Maryland portion of the Chesapeake Bay was conducted. These small ponds occur commonly along the Bay shore. A sand berm separates the freshwaters of the ponds from the saline waters of the Bay; this berm is occasionally breached permitting interchange between ponds and Bay. A survey of aerial maps and photographs has revealed approximately 1800 ponds bordering the mid and upper Bay.

  19. Abdominal rigidity

    MedlinePlus

    Rigidity of the abdomen ... is a sore area inside the belly or abdomen, the pain will get worse when a hand ... Causes can include: Abscess inside the abdomen Appendicitis ... small intestine, large bowel, or gallbladder ( gastrointestinal ...

  20. Geomagnetic cutoffs: a review for space dosimetry applications.

    PubMed

    Smart, D F; Shea, M A

    1994-10-01

    The earth's magnetic field acts as a shield against charged particle radiation from interplanetary space, technically described as the geomagnetic cutoff. The cutoff rigidity problem (except for the dipole special case) has "no solution in closed form". The dipole case yields the Stormer equation which has been repeatedly applied to the earth in hopes of providing useful approximations of cutoff rigidities. Unfortunately the earth's magnetic field has significant deviations from dipole geometry, and the Stormer cutoffs are not adequate for most applications. By application of massive digital computer power it is possible to determine realistic geomagnetic cutoffs derived from high order simulation of the geomagnetic field. Using this technique, "world-grids" of directional cutoffs for the earth's surface and for a limited number of satellite altitudes have been derived. However, this approach is so expensive and time consuming it is impractical for most spacecraft orbits, and approximations must be used. The world grids of cutoff rigidities are extensively used as lookup tables, normalization points and interpolation aids to estimate the effective geomagnetic cutoff rigidity of a specific location in space. We review the various options for estimating the cutoff rigidity for earth-orbiting satellites.

  1. One strategy to enhance electrochemical properties of Ni-based cathode materials under high cut-off voltage for Li-ion batteries

    NASA Astrophysics Data System (ADS)

    Liang, Longwei; Jiang, Feng; Cao, Yanbing; Hu, Guorong; Du, Ke; Peng, Zhongdong

    2016-10-01

    Well-distributed, nano-sized and amorphous or crystalized NaTi2(PO4)3 (NTP) coating layer with high ionic conductivity is successfully introduced onto the surface of LiNi0.6Co0.2Mn0.2O2 (LNCM) particles by a simple and effective mechanical activation method followed by adjusting the reheating temperature appropriately. The promoting influence of NTP coating on the structure stability, cycle life and high rate capability under elevated cut-off voltage has been investigated in-depth. Particularly for the crystalized NTP-coated LNCM, the main reason for the enhanced electrochemical performance can be attributed to the NTP layer with rhombohedral structure providing convenient and low activation barrier diffusion pathways for Li+ ions to insert/extract the interface of electrode/electrolyte. Besides, the NTP-coated layer with stable structure can effectively inhibit the surface side reaction during the long charge/discharge process under high cut-off voltage, which will reduce the harmful insulative by-products. It's worth mentioning that the cyclic stability of crystalized NTP-coated LNCM between 3.0 and 4.6 V is also improved significantly even under the rigorous test environment.

  2. Triceps and Subscapular Skinfold Thickness Percentiles and Cut-Offs for Overweight and Obesity in a Population-Based Sample of Schoolchildren and Adolescents in Bogota, Colombia

    PubMed Central

    Ramírez-Vélez, Robinson; López-Cifuentes, Mario Ferney; Correa-Bautista, Jorge Enrique; González-Ruíz, Katherine; González-Jiménez, Emilio; Córdoba-Rodríguez, Diana Paola; Vivas, Andrés; Triana-Reina, Hector Reynaldo; Schmidt-RioValle, Jacqueline

    2016-01-01

    The assessment of skinfold thickness is an objective measure of adiposity. The aims of this study were to establish Colombian smoothed centile charts and LMS L (Box–Cox transformation), M (median), and S (coefficient of variation) tables for triceps, subscapular, and triceps + subscapular skinfolds; appropriate cut-offs were selected using receiver operating characteristic (ROC) analysis based on a population-based sample of children and adolescents in Bogotá, Colombia. A cross-sectional study was conducted in 9618 children and adolescents (55.7% girls; age range of 9–17.9 years). Triceps and subscapular skinfold measurements were obtained using standardized methods. We calculated the triceps + subscapular skinfold (T + SS) sum. Smoothed percentile curves for triceps and subscapular skinfold thickness were derived using the LMS method. ROC curve analyses were used to evaluate the optimal cut-off point of skinfold thickness for overweight and obesity, based on the International Obesity Task Force definitions. Subscapular and triceps skinfolds and T + SS were significantly higher in girls than in boys (p < 0.001). The ROC analysis showed that subscapular and triceps skinfolds and T + SS have a high discriminatory power in the identification of overweight and obesity in the sample population in this study. Our results provide sex- and age-specific normative reference standards for skinfold thickness values from a population from Bogotá, Colombia. PMID:27669294

  3. Italians do it worse. Montreal Cognitive Assessment (MoCA) optimal cut-off scores for people with probable Alzheimer's disease and with probable cognitive impairment.

    PubMed

    Bosco, Andrea; Spano, Giuseppina; Caffò, Alessandro O; Lopez, Antonella; Grattagliano, Ignazio; Saracino, Giuseppe; Pinto, Katia; Hoogeveen, Frans; Lancioni, Giulio E

    2017-02-02

    Montreal cognitive assessment (MoCA) is a test providing a brief screening for people with cognitive impairment due to aging or neurodegenerative syndromes. In Italy, as in the rest of the world, several validation studies of MoCA have been carried out. This study compared, for the first time in Italy, a sample of people with probable Alzheimer's Disease (AD) with healthy counterparts. The study also compared two community-dwelling groups of aged participants with and without probable cognitive impairment, as discriminated by two cut-off points of adjusted MMSE score. All the comparisons were carried out according to ROC statistics. Optimal cutoff for a diagnosis of probable AD was a MoCA score ≤14. Optimal cutoff for the discrimination of probable cognitive impairment was a MoCA score ≤17 (associated to MMSE cutoff of 23.8). Results confirm the substantial discrepancy in cut-off points existing between Italian and other international validation studies, showing that Italian performance on MoCA seems to be globally lower than that in other Countries. Characteristics of population might explain these results.

  4. Increased impedance near cut-off in plasma-like media leading to emission of high-power, narrow-bandwidth radiation

    PubMed Central

    Hur, M. S.; Ersfeld, B.; Noble, A.; Suk, H.; Jaroszynski, D. A.

    2017-01-01

    Ultra-intense, narrow-bandwidth, electromagnetic pulses have become important tools for exploring the characteristics of matter. Modern tuneable high-power light sources, such as free-electron lasers and vacuum tubes, rely on bunching of relativistic or near-relativistic electrons in vacuum. Here we present a fundamentally different method for producing narrow-bandwidth radiation from a broad spectral bandwidth current source, which takes advantage of the inflated radiation impedance close to cut-off in a medium with a plasma-like permittivity. We find that by embedding a current source in this cut-off region, more than an order of magnitude enhancement of the radiation intensity is obtained compared with emission directly into free space. The method suggests a simple and general way to flexibly use broadband current sources to produce broad or narrow bandwidth pulses. As an example, we demonstrate, using particle-in-cell simulations, enhanced monochromatic emission of terahertz radiation using a two-colour pumped current source enclosed by a tapered waveguide. PMID:28071681

  5. Triceps and Subscapular Skinfold Thickness Percentiles and Cut-Offs for Overweight and Obesity in a Population-Based Sample of Schoolchildren and Adolescents in Bogota, Colombia.

    PubMed

    Ramírez-Vélez, Robinson; López-Cifuentes, Mario Ferney; Correa-Bautista, Jorge Enrique; González-Ruíz, Katherine; González-Jiménez, Emilio; Córdoba-Rodríguez, Diana Paola; Vivas, Andrés; Triana-Reina, Hector Reynaldo; Schmidt-RioValle, Jacqueline

    2016-09-24

    The assessment of skinfold thickness is an objective measure of adiposity. The aims of this study were to establish Colombian smoothed centile charts and LMS L (Box-Cox transformation), M (median), and S (coefficient of variation) tables for triceps, subscapular, and triceps + subscapular skinfolds; appropriate cut-offs were selected using receiver operating characteristic (ROC) analysis based on a population-based sample of children and adolescents in Bogotá, Colombia. A cross-sectional study was conducted in 9618 children and adolescents (55.7% girls; age range of 9-17.9 years). Triceps and subscapular skinfold measurements were obtained using standardized methods. We calculated the triceps + subscapular skinfold (T + SS) sum. Smoothed percentile curves for triceps and subscapular skinfold thickness were derived using the LMS method. ROC curve analyses were used to evaluate the optimal cut-off point of skinfold thickness for overweight and obesity, based on the International Obesity Task Force definitions. Subscapular and triceps skinfolds and T + SS were significantly higher in girls than in boys (p < 0.001). The ROC analysis showed that subscapular and triceps skinfolds and T + SS have a high discriminatory power in the identification of overweight and obesity in the sample population in this study. Our results provide sex- and age-specific normative reference standards for skinfold thickness values from a population from Bogotá, Colombia.

  6. Increased impedance near cut-off in plasma-like media leading to emission of high-power, narrow-bandwidth radiation

    NASA Astrophysics Data System (ADS)

    Hur, M. S.; Ersfeld, B.; Noble, A.; Suk, H.; Jaroszynski, D. A.

    2017-01-01

    Ultra-intense, narrow-bandwidth, electromagnetic pulses have become important tools for exploring the characteristics of matter. Modern tuneable high-power light sources, such as free-electron lasers and vacuum tubes, rely on bunching of relativistic or near-relativistic electrons in vacuum. Here we present a fundamentally different method for producing narrow-bandwidth radiation from a broad spectral bandwidth current source, which takes advantage of the inflated radiation impedance close to cut-off in a medium with a plasma-like permittivity. We find that by embedding a current source in this cut-off region, more than an order of magnitude enhancement of the radiation intensity is obtained compared with emission directly into free space. The method suggests a simple and general way to flexibly use broadband current sources to produce broad or narrow bandwidth pulses. As an example, we demonstrate, using particle-in-cell simulations, enhanced monochromatic emission of terahertz radiation using a two-colour pumped current source enclosed by a tapered waveguide.

  7. Rocking at 81 and Rolling at 34: ROC Cut-Off Scores for the Negative Acts Questionnaire–Revised in Serbia

    PubMed Central

    Petrović, Ivana B.; Vukelić, Milica; Čizmić, Svetlana

    2017-01-01

    Researchers are still searching for the ways to identify different categories of employees according to their exposure to negative acts and psychological experience of workplace bullying. We followed Notelaers and Einarsen’s application of the ROC analysis to determine the NAQ-R cut-off scores applying a “lower” and “higher” threshold. The main goal of this research was to develop and test different gold standards of personal and organizational relevance in determining the NAQ-R cut-off scores in a specific cultural and economic context of Serbia. Apart from combining self-labeling as a victim with self-perceived health, the objectives were to test the gold standards developed as a combination of self-labeling with life satisfaction, self-labeling with intention to leave and a complex gold standard based on self-labeling, self-perceived health, life satisfaction and intention to leave taken together. The ROC analysis on Serbian workforce data supports applying of different gold standards. For identifying employees in a preliminary stage of bullying, the most applicable was the gold standard based on self-labeling and intention to leave (score 34 and higher). The most accurate identification of victims could be based on the most complex gold standard (score 81 and higher). This research encourages further investigation of gold standards in different cultures. PMID:28119652

  8. Influence of the Lift-Off Effect on the Cut-Off Frequency of the EMAT-Generated Rayleigh Wave Signal

    PubMed Central

    Yi, Pengxing; Zhang, Kang; Li, Yahui; Zhang, Xuming

    2014-01-01

    The electromagnetic acoustic transducer (EMAT), a non-contact NDT tool with large lift-off, is becoming an attractive method for detecting the cracks in the metal parts. However, the lift-off of the transducer has a direct effect on the feature that is used to characterize the defects. A detailed investigation on the relationship between the feature and the lift-off of the EMAT is crucial in the detection process. This paper investigates the lift-off effect on the feature, cut-off frequency of EMAT in the Rayleigh wave. The study can be divided into two parts. Firstly, with a multi-field coupling environment, 2-D electromagnetic and wave generation EMAT models are built to simulate the interaction of the Rayleigh wave with the surface crack. Then, the lift-off effect on the cut-off frequency is investigated through simulation and experiment. Compared to the previous studies, it is found that lift-off would cause a negative result when the lift-off varies in the testing process. Besides, the calibration obtained from the tests at a random lift-off value can be used in other tests with any different lift off value provided that the lift-off is kept as a constant during the detection process. PMID:25340446

  9. Soro West: A non-seismically defined, fault cut-off prospect in the Papuan Fold and Thrust Belt, Papua New Guinea

    SciTech Connect

    Robinson, W.F.; Swift, C.M. Jr.

    1996-12-31

    Soro West is a fault cut-off prospect located in the frontal portion of the Papuan Fold and Thrust Belt. Prospective Toro and Imburu sandstones are interpreted to be in the hanging wall of the Soro Thrust. Truncation against the thrust, both updip and through lateral ramps, provides the trapping mechanism. The Soro West Prospect was defined using geological, geochemical, remote sensing, and geophysical data. The definition and location of the trap is a primary risk and work was focused on this aspect. Surface geological data (lithology, strikes, and dips) topography and synthetic aperture radar imagery were incorporated into the evaluation. Statistical curvature analysis techniques helped define the shape of the structure and the locations of the lateral ramps. Strontium isotope analyses of Darai Limestone surface samples refined erosional levels using a locally-derived reference curve. Severe karst precludes the acquisition of coherent surface seismic data, so the primary geophysical tool used was magnetotellurics (MT). A detailed, pre-survey feasibility study defined expected responses from alternative structural models. The MT data demonstrated that the limestone at surface is underlain by thick conductive clastics and not another Darai Limestone sheet. The data also constrained the range of fault cut-off positions significantly. Multiple, three-dimensionally consistent, restorable alternative structural models were created using results from all analyses. These led to a positive assessment of the prospect and an exploratory test is to be drilled in 1996.

  10. A cut-off of 2150 cytokeratin 19 mRNA copy number in sentinel lymph node may be a powerful predictor of non-sentinel lymph node status in breast cancer patients

    PubMed Central

    Terrenato, Irene; D’Alicandro, Valerio; Casini, Beatrice; Perracchio, Letizia; Rollo, Francesca; De Salvo, Laura; Di Filippo, Simona; Di Filippo, Franco; Pescarmona, Edoardo; Maugeri-Saccà, Marcello; Mottolese, Marcella

    2017-01-01

    Since 2007, one-step nucleic acid amplification (OSNA) has been used as a diagnostic system for sentinel lymph node (SLN) examination in patients with breast cancer. This study aimed to define a new clinical cut-off of CK19 mRNA copy number based on the calculation of the risk that an axillary lymph node dissection (ALND) will be positive. We analyzed 1529 SLNs from 1140 patients with the OSNA assay and 318 patients with positive SLNs for micrometastasis (250 copies) and macrometastasis (5000 copies) underwent ALND. Axillary non–SLNs were routinely examined. ROC curves and Youden’s index were performed in order to identify a new cut-off value. Logistic regression models were performed in order to compare OSNA categorical variables created on the basis of our and traditional cut-off to better identify patients who really need an axillary dissection. 69% and 31% of OSNA positive patients had a negative and positive ALND, respectively. ROC analysis identified a cut-off of 2150 CK19 mRNA copies with 95% sensitivity and 51% specificity. Positive and negative predictive values of this new cut-off were 47% and 96%, respectively. Logistic regression models indicated that the cut-off of 2150 copies better discriminates patients with node negative or positive in comparison with the conventional OSNA cut-off (p<0.0001). This cut-off identifies false positive and false negative cases and true-positive and true negative cases very efficiently, and therefore better identifies which patients really need an ALND and which patients can avoid one. This is why we suggest that the negative cut-off should be raised from 250 to 2150. Furthermore, we propose that for patients with a copy number that ranges between 2150 and 5000, there should be a multidisciplinary discussion concerning the clinical and bio-morphological features of primary breast cancer before any decision is taken on whether to perform an ALND or not. PMID:28187209

  11. The cut-off value for interleukin 34 as an additional potential inflammatory biomarker for the prediction of the risk of diabetic complications.

    PubMed

    Zorena, Katarzyna; Jachimowicz-Duda, Olga; Wąż, Piotr

    2016-01-01

    In the present study, we have decided to evaluate whether serum interleukin 34 (IL-34) levels may have diagnostic value in predicting the risk of vascular diabetic complications. The study included 49 patients with type 2 diabetes mellitus (T2DM) and 23 high-risk group. The receiver operating characteristic (ROC) curve analysis has shown that IL-34 has more discriminatory power than C-reactive protein (CRP) for the risk of diabetic complications. The cut-off value for IL-34 was established as 91.2 pg/mL. The gist of our research was identification of IL-34 as an additional potential inflammatory biomarker for the prediction of the risk of vascular diabetic complications.

  12. The optimum cut-off value to differentiate Echinococcus granulosus sensu stricto from other species of E. granulosus sensu lato using larval rostellar hook morphometry.

    PubMed

    Soriano, S V; Pierangeli, N B; Pianciola, L A; Mazzeo, M; Lazzarini, L E; Debiaggi, M F; Bergagna, H F J; Basualdo, J A

    2015-01-01

    Cystic echinococcosis caused by Echinococcus granulosus sensu lato is one of the most important helminth zoonoses in the world; it affects both humans and livestock. The disease is endemic in Argentina and highly endemic in the province of Neuquén. Considerable genetic and phenotypic variation has been demonstrated in E. granulosus, and ten different genotypes (G1-G10) have been identified using molecular tools. Echinococcus granulosus sensu lato may be considered a species complex, comprised of E. granulosus sensu stricto (G1-G3), E. equinus (G4), E. ortleppi (G5) and E. canadensis (G6-G10). In endemic areas, the characterization of cystic echinococcosis molecular epidemiology is important in order to apply adequate control strategies. A cut-off value for larval large hook total length to distinguish E. granulosus sensu stricto isolates from those produced by other species of the complex was defined for the first time. Overall, 1780 larval hooks of 36 isolates obtained from sheep (n= 11, G1), goats (n= 10, G6), cattle (n= 5, G6) and pigs (n= 10, G7) were analysed. Validation against molecular genotyping as gold standard was carried out using the receiver operating characteristic (ROC) curve analysis. The optimum cut-off value was defined as 26.5 μm. The proposed method showed high sensitivity (97.8%) and specificity (91.1%). Since in most endemic regions the molecular epidemiology of echinococcosis includes the coexistence of the widely distributed E. granulosus sensu stricto G1 strain and other species of the complex, this technique could be useful as a quick and economical tool for epidemiological and surveillance field studies, when fertile cysts are present.

  13. Clonidine-stimulated growth hormone concentrations (cut-off values) measured by immunochemiluminescent assay (ICMA) in children and adolescents with short stature

    PubMed Central

    de Fátima Borges, Maria; Teixeira, Flávia Carolina Cândida; Feltrin, Aline Karin; Ribeiro, Karina Alvarenga; Nascentes, Gabriel Antonio Nogueira; Resende, Elisabete Aparecida Mantovani Rodrigues; Ferreira, Beatriz Pires; Silva, Adriana Paula; Palhares, Heloísa Marcelina Cunha

    2016-01-01

    OBJECTIVES: To establish cut-off values for growth hormone concentrations using clonidine as a secretagogue and an immunochemiluminescent assay as the method of measurement and to analyze the response time as well as the influence of gender, nutritional status and pubertal stage. METHODS: A total of 225 tests were performed in 3 patient groups, categorized as group 1 (normal), group 2 (idiopathic short stature) and group 3 (growth hormone deficiency). Among the 199 disease-free individuals, 138 were prepubertal, and 61 were pubertal. Clonidine (0.1 mg/m2) was orally administered, and the growth hormone level was measured by immunochemiluminescent assay. The growth hormone peak and the difference between the growth hormone peak and the baseline level were then analyzed. Statistical analyses were performed using Student's t-test or the Mann-Whitney test and Kruskal-Wallis test followed by Dunn's post hoc test. Cut-off values were determined using a receiver operating characteristic curve. RESULTS: Group 1 and group 2 had no difference in growth hormone peak, gender, body mass index standard deviation score, or pubertal stage. Group 3 exhibited a significantly lower growth hormone peak than the other groups did. The receiver operating characteristic curve demonstrated that growth hormone concentrations ≥ 3.0 ng/mL defined responsiveness to clonidine. In total, 3.02% of individuals in group 1 and group 2 were considered false positive, i.e., these children lacked growth hormone deficiency and had a peak below 3.0 ng/mL. CONCLUSION: Clonidine-stimulated growth hormone concentrations ≥3 ng/mL, as measured by immunochemiluminescent assay, suggest responsiveness to the stimulus regardless of gender, body mass index standard deviation score or pubertal stage. PMID:27166774

  14. Utilization of a detection level of 25ng/mL for cannabinoids in urine using a CEDIA THCPLUS immunoassay: application of this cut-off to urines of school children.

    PubMed

    Madhavaram, Hima; Couch, Ronald A F

    2010-05-20

    Cannabis is the most widely used illicit drug in New Zealand. About 4 years ago schools in New Zealand began introducing drug programmes in order ascertain a pupil's likely cannabinoid use. Our toxicology laboratory screened such specimens for the presence of cannabinoids, using CEDIA immunoassay, at a cut-off of 50ng/mL as directed by the AS/NZS 4308:2001 standard. However, the consequent result that we reported, as not detected (<50ng/mL), in many cases did not parallel the pupil's confessed cannabis use. Our laboratory has therefore used a lower cut-off of 25ng/mL, by this immunoassay. We use this cut-off only for non-evidential analyses. Stored specimens were analysed over two time periods. Initially 2359 urine samples were screened for cannabinoids. 130 of these specimens had a value between 25 and 49ng/mL and 60 of this group were randomly selected for confirmation by GC-MS. In all the 60 specimens, the presence of THCCOOH was confirmed. A further 760 specimens were collected over a later time period. Of these, 48 specimens had an immunoassay value of 25-49ng/mL and all 48 specimens were confirmed positive for THCCOOH by GC-MS. This study indicates that the CEDIA THCPLUS immunoassay can be used to screen for the presence of urinary cannabinoids using a 25ng/mL cut-off. Use of such a cut-off will limit the occurrence of false negative cannabinoid screening results. For school children a lower cut-off may be important, as consequent remedial action, following a positive immunoassay result, may limit the adverse outcomes such as dependence and impairment of achievements as suggested in a New Zealand study by Fergusson and Joseph.

  15. Geomagnetism-Paleomagnetism Committee

    NASA Astrophysics Data System (ADS)

    Banerjee, Subir K.

    I n response to strong member concerns about the future of geomagnetism, Neil D. Opdyke, President of the Geomagnetism and Paleomagnetism Section, has appointed an ad hoc Committee for the Future of Geomagnetism and Paleomagnetism consisting of Subir K. Banerjee (chair; University of Minnesota, Minneapolis), Joseph Cain (U.S. Geological Survey, Denver, Colo.) and Rob Van der Voo (University of Michigan, Ann Arbor). The committee seeks, from the membership at large, perceptions of future directions of research, help in identifying a few expanding research areas that show a promise of delivering significant results in the next 5 to 10 years, and guidance in generating a strategy to bring these about.

  16. The Optimal Ethnic-Specific Waist-Circumference Cut-Off Points of Metabolic Syndrome among Low-Income Rural Uyghur Adults in Far Western China and Implications in Preventive Public Health

    PubMed Central

    He, Jia; Ma, Rulin; Liu, Jiaming; Zhang, Mei; Ding, Yusong; Guo, Heng; Mu, Lati; Zhang, Jingyu; Wei, Bin; Yan, Yizhong; Ma, Jiaolong; Pang, Hongrui; Li, Shugang; Guo, Shuxia

    2017-01-01

    Background: Metabolic syndrome is pandemic; however, the cut-off values for waist circumference (WC) vary widely depending on the ethnic groups studied and the criteria applied for WC measurement. Previous studies for defining optimal WC cut-off points included high-income and urban settings, and did not cover low-income, rural settings, especially for ethnic minorities. This study aimed at defining optimal ethnic-specific WC cut-off points in a low-income, rural population comprising the largest inhabitant minority group residing in far Western China. Methods: Questionnaire-based surveys, physical examinations, and blood testing of 3542 individuals were conducted in 2010, using a stratified cluster random sampling method in rural Uyghur residents (≥18 years old) from 12 villages in Xinjiang, China, approximately 4407 km away from the capital city, Beijing. Metabolic syndrome was defined according to the International Diabetes Federation (IDF) criteria. Optimal, ethnic-specific WC cut-off values for diagnosing metabolic syndrome were determined using receiver operator characteristic (ROC) curve analysis. Results: As WC increased, there was a significant, increasing trend of detection and risk in rural Uyghur adults, regardless of the presence of ≥1 or ≥2 components of metabolic syndrome by IDF criteria. The optimal ethnic-specific WC cut-off point to predict the presence of metabolic syndrome was 85 cm for men and 82 cm for women. With these cut-off points, the prevalence rates of metabolic syndrome among men, women, and overall population in Uyghur adults were 19.5%, 23.0%, and 21.3%, respectively. Conclusions: We report a high prevalence of metabolic syndrome, especially in women, among rural Uyghurs in Western China. A WC cut-off of 85 cm in men and 82 cm in women was the best predictor of metabolic syndrome in this population. Because of the cost-effectiveness in measuring WC, we recommend that these WC cut-off points be integrated into local preventive

  17. Cut-Off Points for Mild, Moderate, and Severe Pain on the Numeric Rating Scale for Pain in Patients with Chronic Musculoskeletal Pain: Variability and Influence of Sex and Catastrophizing

    PubMed Central

    Boonstra, Anne M.; Stewart, Roy E.; Köke, Albère J. A.; Oosterwijk, René F. A.; Swaan, Jeannette L.; Schreurs, Karlein M. G.; Schiphorst Preuper, Henrica R.

    2016-01-01

    Objectives: The 0–10 Numeric Rating Scale (NRS) is often used in pain management. The aims of our study were to determine the cut-off points for mild, moderate, and severe pain in terms of pain-related interference with functioning in patients with chronic musculoskeletal pain, to measure the variability of the optimal cut-off points, and to determine the influence of patients’ catastrophizing and their sex on these cut-off points. Methods: 2854 patients were included. Pain was assessed by the NRS, functioning by the Pain Disability Index (PDI) and catastrophizing by the Pain Catastrophizing Scale (PCS). Cut-off point schemes were tested using ANOVAs with and without using the PSC scores or sex as co-variates and with the interaction between CP scheme and PCS score and sex, respectively. The variability of the optimal cut-off point schemes was quantified using bootstrapping procedure. Results and conclusion: The study showed that NRS scores ≤ 5 correspond to mild, scores of 6–7 to moderate and scores ≥8 to severe pain in terms of pain-related interference with functioning. Bootstrapping analysis identified this optimal NRS cut-off point scheme in 90% of the bootstrapping samples. The interpretation of the NRS is independent of sex, but seems to depend on catastrophizing. In patients with high catastrophizing tendency, the optimal cut-off point scheme equals that for the total study sample, but in patients with a low catastrophizing tendency, NRS scores ≤ 3 correspond to mild, scores of 4–6 to moderate and scores ≥7 to severe pain in terms of interference with functioning. In these optimal cut-off schemes, NRS scores of 4 and 5 correspond to moderate interference with functioning for patients with low catastrophizing tendency and to mild interference for patients with high catastrophizing tendency. Theoretically one would therefore expect that among the patients with NRS scores 4 and 5 there would be a higher average PDI score for those with low

  18. The Optimal Ethnic-Specific Waist-Circumference Cut-Off Points of Metabolic Syndrome among Low-Income Rural Uyghur Adults in Far Western China and Implications in Preventive Public Health.

    PubMed

    He, Jia; Ma, Rulin; Liu, Jiaming; Zhang, Mei; Ding, Yusong; Guo, Heng; Mu, Lati; Zhang, Jingyu; Wei, Bin; Yan, Yizhong; Ma, Jiaolong; Pang, Hongrui; Li, Shugang; Guo, Shuxia

    2017-02-08

    Background: Metabolic syndrome is pandemic; however, the cut-off values for waist circumference (WC) vary widely depending on the ethnic groups studied and the criteria applied for WC measurement. Previous studies for defining optimal WC cut-off points included high-income and urban settings, and did not cover low-income, rural settings, especially for ethnic minorities. This study aimed at defining optimal ethnic-specific WC cut-off points in a low-income, rural population comprising the largest inhabitant minority group residing in far Western China. Methods: Questionnaire-based surveys, physical examinations, and blood testing of 3542 individuals were conducted in 2010, using a stratified cluster random sampling method in rural Uyghur residents (≥18 years old) from 12 villages in Xinjiang, China, approximately 4407 km away from the capital city, Beijing. Metabolic syndrome was defined according to the International Diabetes Federation (IDF) criteria. Optimal, ethnic-specific WC cut-off values for diagnosing metabolic syndrome were determined using receiver operator characteristic (ROC) curve analysis. Results: As WC increased, there was a significant, increasing trend of detection and risk in rural Uyghur adults, regardless of the presence of ≥1 or ≥2 components of metabolic syndrome by IDF criteria. The optimal ethnic-specific WC cut-off point to predict the presence of metabolic syndrome was 85 cm for men and 82 cm for women. With these cut-off points, the prevalence rates of metabolic syndrome among men, women, and overall population in Uyghur adults were 19.5%, 23.0%, and 21.3%, respectively. Conclusions: We report a high prevalence of metabolic syndrome, especially in women, among rural Uyghurs in Western China. A WC cut-off of 85 cm in men and 82 cm in women was the best predictor of metabolic syndrome in this population. Because of the cost-effectiveness in measuring WC, we recommend that these WC cut-off points be integrated into local preventive

  19. Cut-Off Points for Mild, Moderate, and Severe Pain on the Numeric Rating Scale for Pain in Patients with Chronic Musculoskeletal Pain: Variability and Influence of Sex and Catastrophizing.

    PubMed

    Boonstra, Anne M; Stewart, Roy E; Köke, Albère J A; Oosterwijk, René F A; Swaan, Jeannette L; Schreurs, Karlein M G; Schiphorst Preuper, Henrica R

    2016-01-01

    Objectives: The 0-10 Numeric Rating Scale (NRS) is often used in pain management. The aims of our study were to determine the cut-off points for mild, moderate, and severe pain in terms of pain-related interference with functioning in patients with chronic musculoskeletal pain, to measure the variability of the optimal cut-off points, and to determine the influence of patients' catastrophizing and their sex on these cut-off points. Methods: 2854 patients were included. Pain was assessed by the NRS, functioning by the Pain Disability Index (PDI) and catastrophizing by the Pain Catastrophizing Scale (PCS). Cut-off point schemes were tested using ANOVAs with and without using the PSC scores or sex as co-variates and with the interaction between CP scheme and PCS score and sex, respectively. The variability of the optimal cut-off point schemes was quantified using bootstrapping procedure. Results and conclusion: The study showed that NRS scores ≤ 5 correspond to mild, scores of 6-7 to moderate and scores ≥8 to severe pain in terms of pain-related interference with functioning. Bootstrapping analysis identified this optimal NRS cut-off point scheme in 90% of the bootstrapping samples. The interpretation of the NRS is independent of sex, but seems to depend on catastrophizing. In patients with high catastrophizing tendency, the optimal cut-off point scheme equals that for the total study sample, but in patients with a low catastrophizing tendency, NRS scores ≤ 3 correspond to mild, scores of 4-6 to moderate and scores ≥7 to severe pain in terms of interference with functioning. In these optimal cut-off schemes, NRS scores of 4 and 5 correspond to moderate interference with functioning for patients with low catastrophizing tendency and to mild interference for patients with high catastrophizing tendency. Theoretically one would therefore expect that among the patients with NRS scores 4 and 5 there would be a higher average PDI score for those with low

  20. On Saturnian cosmic ray cutoff rigidities

    NASA Astrophysics Data System (ADS)

    Sauer, H. H.

    1980-03-01

    It has been determined that Saturn possesses a relatively pure dipolar magnetic field through magnetometer measurements made by Ness et al. (1979, private comm.) and Smith et al. (1979). The paper briefly outlines the dipole geomagnetic cutoff theory and demonstrates the scaling required for its applicability to energetic particle measurements in the vicinity of Saturn. Since the cutoff rigidity is a function of viewing direction, the effective cutoff rigidity must be determined as an integration over the finite viewing angle of a physical detector.

  1. Geomagnetic excitation of nutation

    NASA Astrophysics Data System (ADS)

    Ron, C.; Vondrák, J.

    2015-08-01

    We tested the hypothesis of Malkin (2013), who demonstrated that the observed changes of Free Core Nutation parameters (phase, amplitude) occur near the epochs of geomagnetic jerks. We found that if the numerical integration of Brzeziński broad-band Liouville equations of atmospheric/oceanic excitations is re-initialized at the epochs of geomagnetic jerks, the agreement between the integrated and observed celestial pole offsets is improved (Vondrák & Ron, 2014). Nevertheless, this approach assumes that the influence of geomagnetic jerks leads to a stepwise change in the position of celestial pole, which is physically not acceptable. Therefore we introduce a simple continuous excitation function that hypothetically describes the influence of geomagnetic jerks, and leads to rapid but continuous changes of pole position. The results of numerical integration of atmospheric/oceanic excitations and this newly introduced excitation are then compared with the observed celestial pole offsets, and prove that the agreement is improved significantly.

  2. Alzheimer's disease dementia as the diagnosis best supported by the cerebrospinal fluid biomarkers: difference in cut-off levels from thai experience.

    PubMed

    Senanarong, V; Siwasariyanon, N; Washirutmangkur, L; Poungvarin, N; Ratanabunakit, C; Aoonkaew, N; Udomphanthurak, S

    2012-01-01

    Objectives. To determine how beta-amyloid 1-42 (Aβ 1-42), total tau (tTau), and phosphorylated tau (pTau) levels in CSF behave in a cohort of Thai patients from the Memory Clinic in Bangkok, Thailand. Methods. During 2009-2011, twenty eight subjects from the memory clinic at Siriraj Hospital had CSF analysis for AD biomarkers. Aβ 1-42, tTau, and pTau (at amino acid 181) were measured in CSF by ELISA technique. Results. Mean of Thai mental state examination (TMSE) of 28 Thai cohort was 16.48 (6.63). Fourteen had AD, ten had non-AD dementia, and four non-cases were those with subjective memory complaint (SMC) without dementia. Mean CSF Aβ 1-42, tTau, ptau (181), and pTau/Aβ 1-42 in the AD group were 241.36 (60.14) pg/mL, 222.79 (212.24) pg/mL, 40.79 (27.84) pg/mL, and 0.18 (0.12) accordingly. Mean CSF Aβ 1-42, tTau, pTau (181), and pTau/Aβ 1-42 in the non-AD dementia group were 430.40 (125.18) pg/mL, 349.30 (692.16) pg/mL, 36.80 (14.90) pg/mL, and 0.09 (0.04) accordingly. Mean CSF Aβ 1-42, tTau, pTau (181), and pTau/Aβ 1-42 in the non-cases with SMC without dementia were 499.75 (93.44) pg/mL, 137.25 (62.74) pg/mL, 31.75 (17.48) pg/mL, and 0.06 (0.02). There is significant difference (P < 0.05) among the 3 groups in CSF Aβ 1-42 and pTau/Aβ 1-42. We propose mean + 1.5 SD of CSF Aβ 1-42 in AD group (331.57 pg/mL) to be the cut-off point in Thai subjects. Conclusion. There are significant different in CSF Aβ 1-42 and CSF p-tau/Aβ 1-42 among those with AD, non-AD dementia and non cases with SMC without dementia in Thai cohort. Cut-off point of CSF Aβ 1-42 of 331.57 pg/mL is suggested in Thai study.

  3. Calculation of the ELISA’s cut-off based on the change-point analysis method for detection of Trypanosoma cruzi infection in Bolivian dogs in the absence of controls

    PubMed Central

    Lardeux, Frédéric; Torrico, Gino; Aliaga, Claudia

    2016-01-01

    In ELISAs, sera of individuals infected by Trypanosoma cruzi show absorbance values above a cut-off value. The cut-off is generally computed by means of formulas that need absorbance readings of negative (and sometimes positive) controls, which are included in the titer plates amongst the unknown samples. When no controls are available, other techniques should be employed such as change-point analysis. The method was applied to Bolivian dog sera processed by ELISA to diagnose T. cruzi infection. In each titer plate, the change-point analysis estimated a step point which correctly discriminated among known positive and known negative sera, unlike some of the six usual cut-off formulas tested. To analyse the ELISAs results, the change-point method was as good as the usual cut-off formula of the form “mean + 3 standard deviation of negative controls”. Change-point analysis is therefore an efficient alternative method to analyse ELISA absorbance values when no controls are available. PMID:27384081

  4. Removal of methadone by extended dialysis using a high cut-off dialyzer: implications for the treatment of overdose and for pain management in patients undergoing light chain removal.

    PubMed

    Arelin, Viktor; Schmidt, Julius J; Kayser, Nathalie; Kühn-Velten, W Nikolaus; Suhling, Hendrik; Eden, Gabriele; Kielstein, Jan T

    2016-06-01

    The synthetic opioid methadone hydrochloride has a low molecular weight of 346 D, a high volume of distribution (4 - 7 L/kg), and is lipophilic. It is used as an analgesic and for the maintenance treatment of opiate dependence. In drug addicts, methadone is frequently involved in mixed intoxications that can lead to death. Here we present the case of a drug addict in whom a high cut-off dialysis membrane together with extended dialysis was used in the setting of suspected overdose and acute kidney injury. Although the observed dialyzer plasma clearance (31.5 mL/min) and reduction ratio (38%) were higher than previously reported for standard hemodialysis, the total amount of methadone in the spent dialysate after 1 extended dialysis session was quite low. Hence, even extended dialysis with a high cut-off membrane does not seem to offer a clinically relevant benefit in the setting of overdose for enhanced methadone removal. On the other hand, in patients undergoing high cut-off dialysis for the removal of light chains, methadone could still be used as an analgesic without an additional dose after high cut-off hemodialysis.

  5. Optimal cut-off of homeostasis model assessment of insulin resistance (HOMA-IR) for the diagnosis of metabolic syndrome: third national surveillance of risk factors of non-communicable diseases in Iran (SuRFNCD-2007)

    PubMed Central

    2010-01-01

    Aim We have recently determined the optimal cut-off of the homeostatic model assessment of insulin resistance for the diagnosis of insulin resistance (IR) and metabolic syndrome (MetS) in non-diabetic residents of Tehran, the capital of Iran. The aim of the present study is to establish the optimal cut-off at the national level in the Iranian population with and without diabetes. Methods Data of the third National Surveillance of Risk Factors of Non-Communicable Diseases, available for 3,071 adult Iranian individuals aging 25-64 years were analyzed. MetS was defined according to the Adult Treatment Panel III (ATPIII) and International Diabetes Federation (IDF) criteria. HOMA-IR cut-offs from the 50th to the 95th percentile were calculated and sensitivity, specificity, and positive likelihood ratio for MetS diagnosis were determined. The receiver operating characteristic (ROC) curves of HOMA-IR for MetS diagnosis were depicted, and the optimal cut-offs were determined by two different methods: Youden index, and the shortest distance from the top left corner of the curve. Results The area under the curve (AUC) (95%CI) was 0.650 (0.631-0.670) for IDF-defined MetS and 0.683 (0.664-0.703) with the ATPIII definition. The optimal HOMA-IR cut-off for the diagnosis of IDF- and ATPIII-defined MetS in non-diabetic individuals was 1.775 (sensitivity: 57.3%, specificity: 65.3%, with ATPIII; sensitivity: 55.9%, specificity: 64.7%, with IDF). The optimal cut-offs in diabetic individuals were 3.875 (sensitivity: 49.7%, specificity: 69.6%) and 4.325 (sensitivity: 45.4%, specificity: 69.0%) for ATPIII- and IDF-defined MetS, respectively. Conclusion We determined the optimal HOMA-IR cut-off points for the diagnosis of MetS in the Iranian population with and without diabetes. PMID:20374655

  6. Evaluation of epidemiological cut-off values indicates that biocide resistant subpopulations are uncommon in natural isolates of clinically-relevant microorganisms.

    PubMed

    Morrissey, Ian; Oggioni, Marco Rinaldo; Knight, Daniel; Curiao, Tania; Coque, Teresa; Kalkanci, Ayse; Martinez, Jose Luis

    2014-01-01

    To date there are no clear criteria to determine whether a microbe is susceptible to biocides or not. As a starting point for distinguishing between wild-type and resistant organisms, we set out to determine the minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) distributions for four common biocides; triclosan, benzalkonium chloride, chlorhexidine and sodium hypochlorite for 3319 clinical isolates, with a particular focus on Staphylococcus aureus (N = 1635) and Salmonella spp. (N = 901) but also including Escherichia coli (N = 368), Candida albicans (N = 200), Klebsiella pneumoniae (N = 60), Enterobacter spp. (N = 54), Enterococcus faecium (N = 53), and Enterococcus faecalis (N = 56). From these data epidemiological cut-off values (ECOFFs) are proposed. As would be expected, MBCs were higher than MICs for all biocides. In most cases both values followed a normal distribution. Bimodal distributions, indicating the existence of biocide resistant subpopulations were observed for Enterobacter chlorhexidine susceptibility (both MICs and MBCs) and the susceptibility to triclosan of Enterobacter (MBC), E. coli (MBC and MIC) and S. aureus (MBC and MIC). There is a concern on the potential selection of antibiotic resistance by biocides. Our results indicate however that resistance to biocides and, hence any potential association with antibiotic resistance, is uncommon in natural populations of clinically relevant microorganisms.

  7. Determining cut-off values for neck circumference as a measure of the metabolic syndrome amongst a South African cohort: the SABPA study.

    PubMed

    Hoebel, S; Malan, L; de Ridder, J H

    2012-10-01

    The aim was to determine receiver operating characteristic (ROC) neck circumference (NC) cut offs best associated with the metabolic syndrome (MetS) in a South African cohort. We included 409 urban Africans and Caucasians and stratified them into gender and age groups (25-45 years; 45-65 years). Measurements included anthropometric, fasting overnight urine and biological markers for the MetS (systolic and diastolic blood pressure, glucose, triglycerides, and high density lipoprotein). ROC analysis determined pathological (NC) cut-points of 39 and 35 cm for young and older African men; 32 and 35 cm for young and old African women; 40 and 41 cm for Caucasian men; 34 and 33 cm for Caucasian women. Pathological NC cut-points significantly predicted MetS in all ethnic-gender-age groups except in African women (ORs 2.3-5.4; 95% CI 1.36-16.5). Multiple regression analyses revealed that MetS prevalence and ROC cut-points were not associated with renal impairment in any groups. ROC NC cut-points demonstrated that NC may be used as an additional anthropometric marker to predict the MetS in a South African cohort but not in African women.

  8. The Influence of the Changing Geomagnetic Field on Cosmic Ray Measurements

    DTIC Science & Technology

    1990-01-01

    spectrum a station in the equatorial regions is required. Unfortunately the station with the longest history of operation is located in Huancayo , Peru...the Huancayo neutron monitor prior to any correction for the decrease in the geomagnetic field over the 35-year period. A decreasing cutoff rigidity...at Huancayo (COOPIER and SIMPSON, 1979). Efforts are now underway to correct these cosmic ray intensity values for the changes in the geomagnetic

  9. Specific cut-off points for waist circumference and waist-to-height ratio as predictors of cardiometabolic risk in Black subjects: a cross-sectional study in Benin and Haiti

    PubMed Central

    EL Mabchour, Asma; Delisle, Hélène; Vilgrain, Colette; Larco, Philippe; Sodjinou, Roger; Batal, Malek

    2015-01-01

    Purpose Waist circumference (WC) and waist-to-height ratio (WHtR) are widely used as indicators of abdominal adiposity and the cut-off values have been validated primarily in Caucasians. In this study we identified the WC and WHtR cut-off points that best predicted cardiometabolic risk (CMR) in groups of African (Benin) and African ancestry (Haiti) Black subjects. Methods This cross-sectional study included 452 apparently healthy subjects from Cotonou (Benin) and Port-au-Prince (Haiti), 217 women and 235 men from 25 to 60 years. CMR biomarkers were the metabolic syndrome components. Additional CMR biomarkers were a high atherogenicity index (total serum cholesterol/high density lipoprotein cholesterol ≥4 in women and ≥5 in men); insulin resistance set at the 75th percentile of the calculated Homeostasis Model Assessment index (HOMA-IR); and inflammation defined as high-sensitivity C-reactive protein (hsCRP) concentrations between 3 and 10 mg/L. WC and WHtR were tested as predictors of two out of the three most prevalent CMR biomarkers. Receiver operating characteristic (ROC) curves, Youden’s index, and likelihood ratios were used to assess the performance of specific WC and WHtR cut-offs. Results High atherogenicity index (59.5%), high blood pressure (23.2%), and insulin resistance (25% by definition) were the most prevalent CMR biomarkers in the study groups. WC and WHtR were equally valid as predictors of CMR. Optimal WC cut-offs were 80 cm and 94 cm in men and women, respectively, which is exactly the reverse of the generic cut-offs. The standard 0.50 cut-off of WHtR appeared valid for men, but it had to be increased to 0.59 in women. Conclusion CMR was widespread in these population groups. The present study suggests that in order to identify Africans with high CMR, WC thresholds will have to be increased in women and lowered in men. Data on larger samples are needed. PMID:26604808

  10. [Establishment of a cut-off value for the diagnosis of acute myocardial infarction using a new CK-MB activity measurement reagent containing anti-MtCK antibody].

    PubMed

    Murakami, Mariko; Kodama, Mayumi; Yoshida, Risa; Asada, Takashi; Sano, Takahiro; Sano, Michitaka; Kamakura, Shiro; Nonogi, Hiroshi

    2011-07-01

    CK-MB is an important marker for the diagnosis of acute myocardial infarction (AMI). Since mitochondrial CK (MtCK) is universally present in the blood of healthy individuals, it is known to positively affect the measurement of CK-MB using the immunoinhibition method, causing false-positive results. We performed basic evaluation of ACCURAS AUTO CK-MB MtO, a new reagent containing anti-MtCK antibody that inhibits MtCK activity, and attempted to calculate a cut-off CK-MB level to diagnose AMI. The measurement was performed in samples submitted to the Clinical Laboratory of our center for the measurement of CK-MB. This method was confirmed to have satisfactory basic attributes concerning the reproducibility, linearity, lower detection limit, and effects of interfering substances. When 2886 samples were examined using this and conventional methods, the results of the two methods were correlated in some but not in others. In the samples that showed no correlation, MtCK was demonstrated by isozyme analysis using electrophoresis. The AUC calculated from the ROC curve in AMI patients was 0.912 with this method and 0.861 with the conventional method. The sensitivity and specificity of the new method were higher than those of the conventional method. The cut-off value determined by ROC analysis was 7.7 U/l using the new method and 13.6 U/l using the conventional method, causing an increase in false-positive results compared with the cut off value of 25 U/l widely used for the conventional method to date. However, the cut-off value for the new method that yielded a specificity comparable to 99.1%, which is the specificity of the conventional method using a cut-off value of 25 U/l, was 12 U/l. With a cut-off value of 12 U/l, the sensitivity was improved compared with that employing the conventional method, and both the sensitivity and specificity became comparable to those of the CK-MB mass method. This method is very useful for the accurate measurement of CK-MB activity.

  11. Cut off from supplies - sulfate exhaustion and implications for methane emissions in a brackish rewetted peatland after separation from the coast

    NASA Astrophysics Data System (ADS)

    Koebsch, Franziska; Liu, Bo; Schmiedinger, Iris; Spitzy, Alejandro; Köhler, Stefan; Koch, Marian; Jurasinski, Gerald; Gehre, Matthias; Sachs, Torsten; Böttcher, Michael

    2016-04-01

    Coastal ecosystems are at the interface between marine and freshwater and exhibit a special geochemistry. We investigate the S and C geochemistry of a coastal, degraded fen peatland. The site has been cut off from the Baltic Sea since 1995 and was rewetted with freshwater from the surrounding catchment in 2010. Despite of locally high pore water sulfate (SO42-) concentrations, the fen turned into a strong source for methane (CH4) with annual budgets up to 0.26±0.06 kg m-2 (Hahn et al. 2015). To reconcile this apparent contradiction we use concentration patterns and stable isotope signatures of water, SO42-, pyrite, dissolved carbon, and CH4 (δ2H, δ13C, δ18O, δ34S) along a transect with increasing distance to the Baltic coastline (300-1500 m). The current peatland geochemistry is characterized by a combination of relict signals reflecting former brackish water intrusion events and indicators of recent human activities such as internal eutrophication and increasing freshwater contribution. The shallow peat layer (depth mostly ≤ 55 cm) exhibited a pronounced vertical gradient with a freshwater-front lying on top of the brackish water layer. S geochemistry was decoupled from present brackish water distribution as marine SO42- was almost completely biotically reduced and converted to pyrite. The remaining pore water SO42- pool was remarkably 34S-enriched in relation to Baltic Sea SO42- (up to +86.4 and +21‰, respectively) and also δ34S-values of pyrite were comparatively high (+4.8‰), thereby demonstrating a distinct reservoir effect under closed-system conditions. However, one of the profiles situated 1150 m from the Baltic Sea coast line exhibited a contrasting S pattern with pronounced excess of isotopically lighter SO42- at depth (up to 32.8 mM and +22.7‰). We hypothesize, that local groundwater seeps might provide electron acceptors such as NO3- for the contemporary oxidation of pyrite. δ13C in DIC exhibited a pronounced vertical shift from -23.9

  12. The impact of cut-off lows on ozone in the upper troposphere and lower stratosphere over Changchun from ozonesonde observations

    NASA Astrophysics Data System (ADS)

    Song, Yushan; Lü, Daren; Li, Qian; Bian, Jianchun; Wu, Xue; Li, Dan

    2016-02-01

    In situ measurements of the vertical structure of ozone were made in Changchun (43.53°N, 125.13°E), China, by the Institute of Atmosphere Physics, in the summers of 2010-13. Analysis of the 89 validated ozone profiles shows the variation of ozone concentration in the upper troposphere and lower stratosphere (UTLS) caused by cut-off lows (COLs) over Changchun. During the COL events, an increase of the ozone concentration and a lower height of the tropopause are observed. Backward simulations with a trajectory model show that the ozone-rich airmass brought by the COL is from Siberia. A case study proves that stratosphere-troposphere exchange (STE) occurs in the COL. The ozone-rich air mass transported from the stratosphere to the troposphere first becomes unstable, then loses its high ozone concentration. This process usually happens during the decay stage of COLs. In order to understand the influence of COLs on the ozone in the UTLS, statistical analysis of the ozone profiles within COLs, and other profiles, are employed. The results indicate that the ozone concentrations of the in-COL profiles are significantly higher than those of the other profiles between ±4 km around the tropopause. The COLs induce an increase in UTLS column ozone by 32% on average. Meanwhile, the COLs depress the lapse-rate tropopause (LRT)/dynamical tropopause height by 1.4/1.7 km and cause the atmosphere above the tropopause to be less stable. The influence of COLs is durable because the increased ozone concentration lasts at least one day after the COL has passed over Changchun. Furthermore, the relative coefficient between LRT height and lower stratosphere (LS) column ozone is -0.62, which implies a positive correlation between COL strength and LS ozone concentration.

  13. Introduction to Geomagnetic Fields

    NASA Astrophysics Data System (ADS)

    Hinze, William J.

    Coincidentally, as I sat down in late October 2003 to read and review the second edition of Wallace H. Campbell's text, Introduction to Geomagnetic Fields, we received warnings from the news media of a massive solar flare and its possible effect on power supply systems and satellite communications. News programs briefly explained the source of Sun-Earth interactions. If you are interested in learning more about the physics of the connection between sun spots and power supply systems and their impact on orbiting satellites, I urge you to become acquainted with Campbell's book. It presents an interesting and informative explanation of the geomagnetic field and its applications to a wide variety of topics, including oil exploration, climate change, and fraudulent claims of the utility of magnetic fields for alleviating human pain. Geomagnetism, the study of the nature and processes of the Earth's magnetic fields and its application to the investigation of the Earth, its processes, and history, is a mature science with a well-developed theoretical foundation and a vast array of observations. It is discussed in varied detail in Earth physics books and most entry-level geoscience texts. The latter treatments largely are driven by the need to discuss paleomagnetism as an essential tool in studying plate tectonics. A more thorough explanation of geomagnetism is needed by many interested scientists in related fields and by laypersons. This is the objective of Campbell's book. It is particularly germane in view of a broad range of geomagnetic topics that are at the forefront of today's science, including environmental magnetism, so-called ``jerks'' observed in the Earth's magnetic field, the perplexing magnetic field of Mars, improved satellite magnetic field observations, and the increasing availability of high-quality continental magnetic anomaly maps, to name only a few.

  14. Improved cycle stability of high-capacity Ni-rich LiNi0.8Mn0.1Co0.1O2 at high cut-off voltage by Li2SiO3 coating

    NASA Astrophysics Data System (ADS)

    Zhao, Enyue; Chen, Minmin; Hu, Zhongbo; Chen, Dongfeng; Yang, Limei; Xiao, Xiaoling

    2017-03-01

    A high cut-off voltage is pretty pivotal for the improvement of the energy density of cathode materials. Unfortunately, high-capacity Ni-rich cathode materials usually show serious capacity attenuation at high cut-off voltage. Herein, we propose a Li2SiO3-surface modification strategy to highly improve the cycle performance of the Ni-rich LiNi0.8Mn0.1Co0.1O2 material at high voltage. The capacity retention of the pristine and Li2SiO3-coated electrodes is 57.6 and 77.7%, respectively, at the cut-off voltage of 4.6 V after 50 cycles. Meanwhile, the problems of polarization and voltage reduction of LiNi0.8Mn0.1Co0.1O2 are also alleviated. Our results show that Li2SiO3-surface modification is a very effective strategy for improving the cycle stability of Ni-rich cathode materials and can be used for other high capacity electrode materials.

  15. Foundations of Geomagnetism

    NASA Astrophysics Data System (ADS)

    Jackson, Andy

    The study of the magnetic field of the Earth, or geomagnetism, is one of the oldest lines of scientific enquiry. Indeed, it has often been said that William Gilbert's De Magnete, published in 1600 and predating Isaac Newton's Principia by 87 years, can claim to be the first true scientific textbook; his study was essentially the first of academic rather than practical interest.What then, we may ask, has been accomplished in the nearly 400 intervening years up to the publication of Foundations of Geomagnetism? In short, a wealth of observational evidence, considerable physical understanding, and a great deal of mathematical apparatus have accrued, placing the subject on a much surer footing.The latter two categories are described in considerable detail, and with attendant rigor, in this book. The sphericity of the Earth means that a frequent theme in the book is the solution of the partial differential equations of electrodynamics in a spherical geometry.

  16. On regional geomagnetic charts

    USGS Publications Warehouse

    Alldredge, L.R.

    1987-01-01

    When regional geomagnetic charts for areas roughly the size of the US were compiled by hand, some large local anomalies were displayed in the isomagnetic lines. Since the late 1960s, when the compilation of charts using computers and mathematical models was started, most of the details available in the hand drawn regional charts have been lost. One exception to this is the Canadian magnetic declination chart for 1980. This chart was constructed using a 180 degrees spherical harmonic model. -from Author

  17. Antimicrobial Susceptibility of Flavobacterium psychrophilum from Chilean Salmon Farms and Their Epidemiological Cut-Off Values Using Agar Dilution and Disk Diffusion Methods

    PubMed Central

    Miranda, Claudio D.; Smith, Peter; Rojas, Rodrigo; Contreras-Lynch, Sergio; Vega, J. M. Alonso

    2016-01-01

    Flavobacterium psychrophilum is the most important bacterial pathogen for freshwater farmed salmonids in Chile. The aims of this study were to determine the susceptibility to antimicrobials used in fish farming of Chilean isolates and to calculate their epidemiological cut-off (COWT) values. A number of 125 Chilean isolates of F. psychrophilum were isolated from reared salmonids presenting clinical symptoms indicative of flavobacteriosis and their identities were confirmed by 16S rRNA polymerase chain reaction. Susceptibility to antibacterials was tested on diluted Mueller-Hinton by using an agar dilution MIC method and a disk diffusion method. The COWT values calculated by Normalized Resistance Interpretation (NRI) analysis allow isolates to be categorized either as wild-type fully susceptible (WT) or as manifesting reduced susceptibility (NWT). When MIC data was used, NRI analysis calculated a COWT of ≤0.125, ≤2, and ≤0.5 μg mL-1 for amoxicillin, florfenicol, and oxytetracycline, respectively. For the quinolones, the COWT were ≤1, ≤0.5, and ≤0.125 μg mL-1 for oxolinic acid, flumequine, and enrofloxacin, respectively. The disk diffusion data sets obtained in this work were extremely diverse and were spread over a wide range. For the quinolones there was a close agreement between the frequencies of NWT isolates calculated using MIC and disk data. For oxolinic acid, flumequine, and enrofloxacin the frequencies were 45, 39, and 38% using MIC data, and 42, 41, and 44%, when disk data were used. There was less agreement with the other antimicrobials, because NWT frequencies obtained using MIC and disk data, respectively, were 24 and 10% for amoxicillin, 8 and 2% for florfenicol, and 70 and 64% for oxytetracycline. Considering that the MIC data was more precise than the disk diffusion data, MIC determination would be the preferred method for susceptibility testing for this species and the NWT frequencies derived from the MIC data sets should be considered

  18. Organ dysfunction during continuous veno-venous high cut-off hemodialysis in patients with septic acute kidney injury: A prospective observational study

    PubMed Central

    Chelazzi, Cosimo; Morettini, Elena; Zamidei, Lucia; Valente, Serafina; Caldini, A. Lucia; Zagli, Giovanni; De Gaudio, A. Raffaele; Romagnoli, Stefano

    2017-01-01

    Background Continuous veno-venous hemodialysis with high cut-off membranes (HCO-CVVHD) removes inflammatory mediators involved in organ dysfunction during sepsis. The aim of the present study was to assess the variations in SOFA score and identify early predictors of short-term mortality in a cohort of patients with septic shock, treated with HCO-CVVHD for acute kidney injury (AKI). Methods An observational prospective multicenter cohort study was conducted in four mixed medical-surgical ICUs. Thirty-eight patients with septic shock and AKI (KDIGO stage≥1) treated with HCO-CVVHD have been included in this study. Patients were divided into Survivors and non-Survivors according to mortality observed at 72nd hr of treatment. The variation of SOFA scores and clinical/biochemical parameters were described over time for the entire population and specifically for Survivors and non-Survivors. Similarly, circulating inflammatory mediators (as IL-6, TNF-a and IL-10) were described over time. A logistic regression analysis was used to identify the baseline clinical and biochemical parameters associated with 72 hrs-ICU mortality. Results Overall, the mean SOFA score was 12±3 at baseline, 10.9±3 at 6hrs, 9.8±3 at 12hrs, 8.9±3.3 at 24 hrs, and 8±3.5 at 48 hrs after HCO-CVVHD initiation; and 6.5±2.7 at 24 hrs and 6.6±3 at 48 hrs after HCO-CVVHD discontinuation. In the multivariate regression analysis, baseline serum lactate levels and AKI stage independently correlated with short-term mortality during HCO-CVVHD. A significant reduction was observed in circulating levels of TNFα and IL-6 among Survivors. Conclusions SOFA score significantly decreased early after initiation of HCO-CVVHD in patients with septic AKI. Baseline lactate levels and the AKI stage resulted to be associated to 72 hrs-ICU-mortality. PMID:28207795

  19. Antimicrobial Susceptibility of Flavobacterium psychrophilum from Chilean Salmon Farms and Their Epidemiological Cut-Off Values Using Agar Dilution and Disk Diffusion Methods.

    PubMed

    Miranda, Claudio D; Smith, Peter; Rojas, Rodrigo; Contreras-Lynch, Sergio; Vega, J M Alonso

    2016-01-01

    Flavobacterium psychrophilum is the most important bacterial pathogen for freshwater farmed salmonids in Chile. The aims of this study were to determine the susceptibility to antimicrobials used in fish farming of Chilean isolates and to calculate their epidemiological cut-off (COWT) values. A number of 125 Chilean isolates of F. psychrophilum were isolated from reared salmonids presenting clinical symptoms indicative of flavobacteriosis and their identities were confirmed by 16S rRNA polymerase chain reaction. Susceptibility to antibacterials was tested on diluted Mueller-Hinton by using an agar dilution MIC method and a disk diffusion method. The COWT values calculated by Normalized Resistance Interpretation (NRI) analysis allow isolates to be categorized either as wild-type fully susceptible (WT) or as manifesting reduced susceptibility (NWT). When MIC data was used, NRI analysis calculated a COWT of ≤0.125, ≤2, and ≤0.5 μg mL(-1) for amoxicillin, florfenicol, and oxytetracycline, respectively. For the quinolones, the COWT were ≤1, ≤0.5, and ≤0.125 μg mL(-1) for oxolinic acid, flumequine, and enrofloxacin, respectively. The disk diffusion data sets obtained in this work were extremely diverse and were spread over a wide range. For the quinolones there was a close agreement between the frequencies of NWT isolates calculated using MIC and disk data. For oxolinic acid, flumequine, and enrofloxacin the frequencies were 45, 39, and 38% using MIC data, and 42, 41, and 44%, when disk data were used. There was less agreement with the other antimicrobials, because NWT frequencies obtained using MIC and disk data, respectively, were 24 and 10% for amoxicillin, 8 and 2% for florfenicol, and 70 and 64% for oxytetracycline. Considering that the MIC data was more precise than the disk diffusion data, MIC determination would be the preferred method for susceptibility testing for this species and the NWT frequencies derived from the MIC data sets should be

  20. On extreme geomagnetic storms

    NASA Astrophysics Data System (ADS)

    Cid, Consuelo; Palacios, Judith; Saiz, Elena; Guerrero, Antonio; Cerrato, Yolanda

    2014-10-01

    Extreme geomagnetic storms are considered as one of the major natural hazards for technology-dependent society. Geomagnetic field disturbances can disrupt the operation of critical infrastructures relying on space-based assets, and can also result in terrestrial effects, such as the Quebec electrical disruption in 1989. Forecasting potential hazards is a matter of high priority, but considering large flares as the only criterion for early-warning systems has demonstrated to release a large amount of false alarms and misses. Moreover, the quantification of the severity of the geomagnetic disturbance at the terrestrial surface using indices as Dst cannot be considered as the best approach to give account of the damage in utilities. High temporal resolution local indices come out as a possible solution to this issue, as disturbances recorded at the terrestrial surface differ largely both in latitude and longitude. The recovery phase of extreme storms presents also some peculiar features which make it different from other less intense storms. This paper goes through all these issues related to extreme storms by analysing a few events, highlighting the March 1989 storm, related to the Quebec blackout, and the October 2003 event, when several transformers burnt out in South Africa.

  1. The national geomagnetic initiative

    NASA Technical Reports Server (NTRS)

    1993-01-01

    The Earth's magnetic field, through its variability over a spectrum of spatial and temporal scales, contains fundamental information on the solid Earth and geospace environment (the latter comprising the atmosphere, ionosphere, and magnetosphere). Integrated studies of the geomagnetic field have the potential to address a wide range of important processes in the deep mantle and core, asthenosphere, lithosphere, oceans, and the solar-terrestrial environment. These studies have direct applications to important societal problems, including resource assessment and exploration, natural hazard mitigation, safe navigation, and the maintenance and survivability of communications and power systems on the ground and in space. Studies of the Earth's magnetic field are supported by a variety of federal and state agencies as well as by private industry. Both basic and applied research is presently supported by several federal agencies, including the National Science Foundation (NSF), U.S. Geological Survey (USGS), U.S. Department of Energy (DOE), National Oceanic and Atmospheric Administration (NOAA), National Aeronautics and Space Administration (NASA), and U.S. Department of Defense (DOD) (through the Navy, Air Force, and Defense Mapping Agency). Although each agency has a unique, well-defined mission in geomagnetic studies, many areas of interest overlap. For example, NASA, the Navy, and USGS collaborate closely in the development of main field reference models. NASA, NSF, and the Air Force collaborate in space physics. These interagency linkages need to be strengthened. Over the past decade, new opportunities for fundamental advances in geomagnetic research have emerged as a result of three factors: well-posed, first-order scientific questions; increased interrelation of research activities dealing with geomagnetic phenomena; and recent developments in technology. These new opportunities can be exploited through a national geomagnetic initiative to define objectives and

  2. Torque Balances on the Taylor Cylinders in the Geomagnetic Data Assimilation

    NASA Technical Reports Server (NTRS)

    Kuang, Weijia; Tangborn, Andrew

    2004-01-01

    In this presentation we report on our continuing effort in geomagnetic data assimilation, aiming at understanding and predicting geomagnetic secular variation on decadal time scales. In particular, we focus on the effect of the torque balances on the cylindrical surfaces in the core co-axial with the Earth's rotation axis (the Taylor cylinders) on the time evolution of assimilated solutions. We use our MoSST core dynamics,model and observed geomagnetic field at the Earth's surface derived via Comprehensive Field Model (CFM) for the geomagnetic data assimilation. In our earlier studies, a model solution is selected randomly from our numerical database. It is then assimilated with the observations such that the poloidal field possesses the same field tomography on the core-mantel boundary (CMB) continued downward from surface observations. This tomography change is assumed to be effective through out the outer core. While this approach allows rapid convergence between model solutions and the observations, it also generates sevee numerical instabilities: the delicate balance between weak fluid inertia and the magnetic torques on the Taylor cylinders are completely altered. Consequently, the assimilated solution diverges quickly (in approximately 10% of the magnetic free-decay time in the core). To improve the assimilation, we propose a partial penetration of the assimilation from the CMB: The full-scale modification at the CMB decreases linearly and vanish at an interior radius r(sub a). We shall examine from our assimilation tests possible relationships between the convergence rate of the model solutions to observations and the cut-off radius r(sub a). A better assimilation shall serve our nudging tests in near future.

  3. Operational Geomagnetic Forecast Service

    NASA Astrophysics Data System (ADS)

    Semeniv, O.; Polonska, A.; Parnowski, A.

    2014-12-01

    The operational forecasting service for real-time geomagnetic indices Dst and Kp was described. The warning time for the Earth to the intersection of the Dst index is 1-4 hours, for the Kp index - 3 hours. The skillscore parameter, which is defined as a decrease of the relative mean square error with respect to the trivial model, was approximately 40% for Dst and 15% for Kp. The service works on-line freely available through STAFF http://www.staff.oma.be/ browser.

  4. Hazards of geomagnetic storms

    USGS Publications Warehouse

    Herzog, D.C.

    1992-01-01

    Geomagnetic storms are large and sometimes rapid fluctuations in the Earth's magnetic field that are related to disturbances on the Sun's surface. Although it is not widely recognized, these transient magnetic disturbances can be a significant hazard to people and property. Many of us know that the intensity of the auroral lights increases during magnetic storms, but few people realize that these storms can also cause massive power outages, interrupt radio communications and satellite operations, increase corrosion in oil and gas pipelines, and lead to spuriously high rejection rates in the manufacture of sensitive electronic equipment. 

  5. Rigid particulate matter sensor

    SciTech Connect

    Hall, Matthew

    2011-02-22

    A sensor to detect particulate matter. The sensor includes a first rigid tube, a second rigid tube, a detection surface electrode, and a bias surface electrode. The second rigid tube is mounted substantially parallel to the first rigid tube. The detection surface electrode is disposed on an outer surface of the first rigid tube. The detection surface electrode is disposed to face the second rigid tube. The bias surface electrode is disposed on an outer surface of the second rigid tube. The bias surface electrode is disposed to face the detection surface electrode on the first rigid tube. An air gap exists between the detection surface electrode and the bias surface electrode to allow particulate matter within an exhaust stream to flow between the detection and bias surface electrodes.

  6. Optimal cut-off values for the homeostasis model assessment of insulin resistance (HOMA-IR) and pre-diabetes screening: Developments in research and prospects for the future.

    PubMed

    Tang, Qi; Li, Xueqin; Song, Peipei; Xu, Lingzhong

    2015-12-01

    Diabetes mellitus (DM) appears to be increasing rapidly, threatening to reduce life expectancy for humans around the globe. The International Diabetes Federation (IDF) has estimated that there will be 642 million people living with the disease by 2040 and half as many again who will be not diagnosed. This means that pre-DM screening is a critical issue. Insulin resistance (IR) has emerged as a major pathophysiological factor in the development and progression of DM since it is evident in susceptible individuals at the early stages of DM, and particularly type 2 DM (T2DM). Therefore, assessment of IR via the homeostasis model assessment of IR (HOMA-IR) is a key index for the primary prevention of DM and is thus found in guidelines for screening of high-risk groups. However, the cut-off values of HOMA-IR differ for different races, ages, genders, diseases, complications, etc. due to the complexity of IR. This hampers the determination of specific cut-off values of HOMA-IR in different places and in different situations. China has not published an official index to gauge IR for primary prevention of T2DM in the diabetic and non-diabetic population except for children and adolescents ages 6-12 years. Hence, this article summarizes developments in research on IR, HOMA-IR, and pre-DM screening in order to provide a reference for optimal cut-off values of HOMA-IR for the diagnosis of DM in the Chinese population.

  7. Optimal Cut-Offs of Homeostasis Model Assessment of Insulin Resistance (HOMA-IR) to Identify Dysglycemia and Type 2 Diabetes Mellitus: A 15-Year Prospective Study in Chinese

    PubMed Central

    Lee, C. H.; Shih, A. Z. L.; Woo, Y. C.; Fong, C. H. Y.; Leung, O. Y.; Janus, E.; Cheung, B. M. Y.; Lam, K. S. L.

    2016-01-01

    Background The optimal reference range of homeostasis model assessment of insulin resistance (HOMA-IR) in normal Chinese population has not been clearly defined. Here we address this issue using the Hong Kong Cardiovascular Risk Factor Prevalence Study (CRISPS), a prospective population-based cohort study with long-term follow-up. Material & Methods In this study, normal glucose tolerance (NGT), impaired fasting glucose (IFG), impaired glucose tolerance (IGT) and type 2 diabetes mellitus (T2DM) were defined according to the 1998 World Health Organization criteria. Dysglycemia referred to IFG, IGT or T2DM. This study comprised two parts. Part one was a cross-sectional study involving 2,649 Hong Kong Chinese subjects, aged 25–74 years, at baseline CRISPS-1 (1995–1996). The optimal HOMA-IR cut-offs for dysglycemia and T2DM were determined by the receiver-operating characteristic (ROC) curve. Part two was a prospective study involving 872 subjects who had persistent NGT at CRISPS-4 (2010–2012) after 15 years of follow-up. Results At baseline, the optimal HOMA-IR cut-offs to identify dysglyceia and T2DM were 1.37 (AUC = 0.735; 95% confidence interval [CI] = 0.713–0.758; Sensitivity [Se] = 65.6%, Specificity [Sp] = 71.3%] and 1.97 (AUC = 0.807; 95% CI = 0.777–0.886; Se = 65.5%, Sp = 82.9%) respectively. These cut-offs, derived from the cross-sectional study at baseline, corresponded closely to the 75th (1.44) and 90th (2.03) percentiles, respectively, of the HOMA-IR reference range derived from the prospective study of subjects with persistent NGT. Conclusions HOMA-IR cut-offs, of 1.4 and 2.0, which discriminated dysglycemia and T2DM respectively from NGT in Southern Chinese, can be usefully employed as references in clinical research involving the assessment of insulin resistance. PMID:27658115

  8. Transient cosmic ray increase associated with a geomagnetic storm

    NASA Technical Reports Server (NTRS)

    Kudo, S.; Wada, M.; Tanskanen, P.; Kodama, M.

    1985-01-01

    On the basis of worldwide network data of cosmic ray nucleonic components, the transient cosmic ray increase due to the depression of cosmic ray cutoff rigidity during a severe geomagnetic storm was investigated in terms of the longitudinal dependence. Multiple correlation analysis among isotropic and diurnal terms of cosmic ray intensity variations and Dst term of the geomagnetic field is applied to each of various station's data. It is shown that the amplitude of the transient cosmic ray increase associated with Dst depends on the local time of the station, and that its maximum phase is found in the evening sector. This fact is consistent with the theoretical estimation based on the azimuthally asymmetric ring current model for the magnetic DS field.

  9. Bayesian inference in geomagnetism

    NASA Technical Reports Server (NTRS)

    Backus, George E.

    1988-01-01

    The inverse problem in empirical geomagnetic modeling is investigated, with critical examination of recently published studies. Particular attention is given to the use of Bayesian inference (BI) to select the damping parameter lambda in the uniqueness portion of the inverse problem. The mathematical bases of BI and stochastic inversion are explored, with consideration of bound-softening problems and resolution in linear Gaussian BI. The problem of estimating the radial magnetic field B(r) at the earth core-mantle boundary from surface and satellite measurements is then analyzed in detail, with specific attention to the selection of lambda in the studies of Gubbins (1983) and Gubbins and Bloxham (1985). It is argued that the selection method is inappropriate and leads to lambda values much larger than those that would result if a reasonable bound on the heat flow at the CMB were assumed.

  10. Thickness-Independent Ultrasonic Imaging Applied to Abrasive Cut-Off Wheels: An Advanced Aerospace Materials Characterization Method for the Abrasives Industry. A NASA Lewis Research Center Technology Transfer Case History

    NASA Technical Reports Server (NTRS)

    Roth, Don J.; Farmer, Donald A.

    1998-01-01

    Abrasive cut-off wheels are at times unintentionally manufactured with nonuniformity that is difficult to identify and sufficiently characterize without time-consuming, destructive examination. One particular nonuniformity is a density variation condition occurring around the wheel circumference or along the radius, or both. This density variation, depending on its severity, can cause wheel warpage and wheel vibration resulting in unacceptable performance and perhaps premature failure of the wheel. Conventional nondestructive evaluation methods such as ultrasonic c-scan imaging and film radiography are inaccurate in their attempts at characterizing the density variation because a superimposing thickness variation exists as well in the wheel. In this article, the single transducer thickness-independent ultrasonic imaging method, developed specifically to allow more accurate characterization of aerospace components, is shown to precisely characterize the extent of the density variation in a cut-off wheel having a superimposing thickness variation. The method thereby has potential as an effective quality control tool in the abrasives industry for the wheel manufacturer.

  11. An approach for the delineation of a generic cut-off value for local respiratory tract irritation by irritating or corrosive substances as a pragmatic tool to fulfill REACH requirements.

    PubMed

    Messinger, H

    2014-04-01

    Under the current European legislation for the Registration, Evaluation, Authorisation and restriction of Chemicals (REACHs) a Derived No Effect Level (DNEL) has to be delineated for acute and chronic inhalation effects. The majority of available experimental studies are performed by the oral route of exposure. Route to route extrapolation poses particular problems for irritating or corrosive substances but the necessity for additional animal studies with inhalation exposure needs to be balanced with the regulatory information requirements. Existing occupational exposure limits (OEL) as surrogate for cut-off limits representing safe exposure under working conditions were grouped under certain criteria for substances that are legally classified in Europe as irritating or corrosive. As a result, it was shown that the OEL for irritating substances in this dataset is not lower than 10mg/m(3) and for corrosives not lower than 1mg/m(3). Under certain conditions these generic limits could be applied as a pragmatic, but still sufficiently reliable and protective upper cut-off limit approach to avoid additional animal tests with irritating or corrosive chemicals. The respective systemic toxicity profiles and physical-chemical properties need to be considered. Specific exclusion criteria for the discussed concept apply.

  12. Which cut-off value of serum anti-Müllerian hormone level can predict poor ovarian reserve, poor ovarian response to stimulation and in vitro fertilization success? A prospective data analysis.

    PubMed

    Ficicioglu, Cem; Cenksoy, Pinar Ozcan; Yildirim, Gazi; Kaspar, Cigdem

    2014-05-01

    The aim of our study is to demonstrate which cut-off value of serum anti-Müllerian hormone (AMH) level can predict poor ovarian reserve, poor ovarian response to stimulation and IVF outcomes. About 311 of 520 women enrolled IVF treatment cycle that meets inclusion criteria were recruited for this prospective data analysis. Data were collected for: age, duration of infertility, basal FSH and AMH level, total dosage of gonadotropins, maximum estradiol levels, duration of stimulations, total number of oocytes retrieved and clinical PR. Mean AMH was 1.76 ± 1.4 ng/ml and mean age was 33.25 ± 5.5 years. Clinical PR was 39.8% (n = 124). AMH was inversely correlated to total dosage of gonadotropins and age, AMH positively had a significant correlation with maximum estradiol levels, duration of stimulations and total number of oocytes retrieved. The patients in both categories of AMH levels, ≤0.5 and ≤1 ng/ml responded poorly to ovarian stimulation, had significantly higher total dosage of gonadotropins used and FSH levels on cycle day 3, lower maximum E2 levels and clinical PR. AMH could be an acceptable screening test in prediction of ovarian reserve, response to ovarian stimulation and PRs. AMH cut-off value ≤1 ng/ml may predict poor ovarian reserve, poor ovarian response to stimulation and IVF outcomes.

  13. Would raising the total cholesterol diagnostic cut-off from 7.5 mmol/L to 9.3 mmol/L improve detection rate of patients with monogenic familial hypercholesterolaemia?

    PubMed Central

    Futema, M.; Kumari, M.; Boustred, C.; Kivimaki, M.; Humphries, S.E.

    2015-01-01

    A previous report suggested that 88% of individuals in the general population with total cholesterol (TC) > 9.3 mmol/L have familial hypercholesterolaemia (FH). We tested this hypothesis in a cohort of 4896 UK civil servants, mean (SD) age 44 (±6) years, using next generation sequencing to achieve a comprehensive genetic diagnosis. 25 (0.5%) participants (mean age 49.2 years) had baseline TC > 9.3 mmol/L, and overall we found an FH-causing mutation in the LDLR gene in seven (28%) subjects. The detection rate increased to 39% by excluding eight participants with triglyceride levels over 2.3 mmol/L, and reached 75% in those with TC > 10.4 mmol/L. By extrapolation, the detection rate would be ∼25% by including all participants with TC > 8.6 mmol/L (2.5 standard deviations from the mean). Based on the 1/500 FH frequency, 30% of all FH-cases in this cohort would be missed using the 9.3 mmol/L cut-off. Given that an overall detection rate of 25% is considered economically acceptable, these data suggest that a diagnostic TC cut-off of 8.6 mmol/L, rather than 9.3 mmol/L would be clinically useful for FH in the general population. PMID:25682026

  14. Correlation Based Geomagnetic Field Modeling

    NASA Astrophysics Data System (ADS)

    Holschneider, M.; Mauerberger, S.; Lesur, V.; Baerenzung, J.

    2015-12-01

    We present a new method for determining geomagnetic field models. It is based on the construction of an a priori correlation structure derived from our knowledge about characteristic length scales and sources of the geomagnetic field. The magnetic field measurements are then seen as correlated random variables too and the inversion process amounts to compute the a posteriori correlation structure using Bayes theorem. We show how this technique allows the statistical separation of the various field contributions and the assessment of their uncertainties.

  15. PAMELA's measurements of geomagnetic cutoff variations during the 14 December 2006 storm

    NASA Astrophysics Data System (ADS)

    Adriani, O.; Barbarino, G. C.; Bazilevskaya, G. A.; Bellotti, R.; Boezio, M.; Bogomolov, E. A.; Bongi, M.; Bonvicini, V.; Bottai, S.; Bruno, A.; Cafagna, F.; Campana, D.; Carlson, P.; Casolino, M.; Castellini, G.; De Donato, C.; Nolfo, G. A.; De Santis, C.; De Simone, N.; Di Felice, V.; Galper, A. M.; Karelin, A. V.; Koldashov, S. V.; Koldobskiy, S.; Krutkov, S. Y.; Kvashnin, A. N.; Leonov, A.; Malakhov, V.; Marcelli, L.; Martucci, M.; Mayorov, A. G.; Menn, W.; Mergé, M.; Mikhailov, V. V.; Mocchiutti, E.; Monaco, A.; Mori, N.; Munini, R.; Osteria, G.; Palma, F.; Panico, B.; Papini, P.; Pearce, M.; Picozza, P.; Ricci, M.; Ricciarini, S. B.; Sarkar, R.; Scotti, V.; Simon, M.; Sparvoli, R.; Spillantini, P.; Stozhkov, Y. I.; Vacchi, A.; Vannuccini, E.; Vasilyev, G. I.; Voronov, S. A.; Yurkin, Y. T.; Zampa, G.; Zampa, N.

    2016-03-01

    Data from the Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics (PAMELA) satellite experiment were used to measure the geomagnetic cutoff for high-energy (≳ 80MeV) protons during the 14 December 2006 geomagnetic storm. The variations of the cutoff latitude as a function of rigidity were studied on relatively short timescales, corresponding to spacecraft orbital periods (˜94 min). Estimated cutoff values were compared with those obtained by means of a trajectory-tracing approach based on a dynamical empirical modeling of the Earth's magnetosphere. We found significant variations in the cutoff latitude, with a maximum suppression of ˜7° at lowest rigidities during the main phase of the storm. The observed reduction in the geomagnetic shielding and its temporal evolution were related to the changes in the magnetospheric configuration, investigating the role of interplanetary magnetic field, solar wind, and geomagnetic parameters. PAMELA's results represent the first direct measurement of geomagnetic cutoffs for protons with kinetic energies in the sub-GeV and GeV region.

  16. a Millennium of Geomagnetism

    NASA Astrophysics Data System (ADS)

    Stern, David P.

    2002-11-01

    The history of geomagnetism began around the year 1000 with the discovery in China of the magnetic compass. Methodical studies of the Earth's field started in 1600 with William Gilbert's De Magnete [Gilbert, 1600] and continued with the work of (among others) Edmond Halley, Charles Augustin de Coulomb, Carl Friedrich Gauss, and Edward Sabine. The discovery of electromagnetism by Hans Christian Oersted and André-Marie Ampére led Michael Faraday to the notion of fluid dynamos, and the observation of sunspot magnetism by George Ellery Hale led Sir Joseph Larmor in 1919 to the idea that such dynamos could sustain themselves naturally in convecting conducting fluids. From that came modern dynamo theory, of both the solar and terrestrial magnetic fields. Paleomagnetic studies revealed that the Earth's dipole had undergone reversals in the distant past, and these became the critical evidence in establishing plate tectonics. Finally, the recent availability of scientific spacecraft has demonstrated the intricacy of the Earth's distant magnetic field, as well as the existence of magnetic fields associated with other planets and with satellites in our solar system.

  17. Rigidity of lattice domes

    NASA Technical Reports Server (NTRS)

    Savelyev, V. A.

    1979-01-01

    The means of ensuring total rigidity of lattice domes, using comparison with solid shells of 1-3 layers are discussed. Irregularities of manufacture, processing, and other factors are considered, as they relate to diminution of rigidity. The discussion uses the concepts of upper and lower critical loads on the structure in question.

  18. Measurements of developing teeth, and carpals and epiphyses of the ulna and radius for assessing new cut-offs at the age thresholds of 10, 11, 12, 13 and 14 years.

    PubMed

    Cameriere, R; De Luca, S; Cingolani, M; Ferrante, L

    2015-08-01

    The minimum age of criminal responsibility is the youngest age at which children may be held liable for infringements of penal laws. New cut-offs at the age thresholds of 10, 11, 12, 13 and 14 years were determined by applying three different methods: measurement of open apices in tooth roots (T); the ratio between the total area of carpal bones and epiphyses of the ulna and radius (HW); and the combined method (THW). The sample consisted of 291 Italian children (152 boys, 139 girls), aged between 5 and 15 years. The sensitivity and specificity were established. As regards THW, specificity reached the maximum of 95% in boys aged 10, and the minimum of 87% in boys aged 11. The best score of the Positive Predictive Value (PPV) was obtained in boys at 10 years with the THW method and the worst in girls of 12 with the HW method.

  19. Extreme geomagnetically induced currents

    NASA Astrophysics Data System (ADS)

    Kataoka, Ryuho; Ngwira, Chigomezyo

    2016-12-01

    We propose an emergency alert framework for geomagnetically induced currents (GICs), based on the empirically extreme values and theoretical upper limits of the solar wind parameters and of d B/d t, the time derivative of magnetic field variations at ground. We expect this framework to be useful for preparing against extreme events. Our analysis is based on a review of various papers, including those presented during Extreme Space Weather Workshops held in Japan in 2011, 2012, 2013, and 2014. Large-amplitude d B/d t values are the major cause of hazards associated with three different types of GICs: (1) slow d B/d t with ring current evolution (RC-type), (2) fast d B/d t associated with auroral electrojet activity (AE-type), and (3) transient d B/d t of sudden commencements (SC-type). We set "caution," "warning," and "emergency" alert levels during the main phase of superstorms with the peak Dst index of less than -300 nT (once per 10 years), -600 nT (once per 60 years), or -900 nT (once per 100 years), respectively. The extreme d B/d t values of the AE-type GICs are 2000, 4000, and 6000 nT/min at caution, warning, and emergency levels, respectively. For the SC-type GICs, a "transient alert" is also proposed for d B/d t values of 40 nT/s at low latitudes and 110 nT/s at high latitudes, especially when the solar energetic particle flux is unusually high.

  20. Prevalence of swallowing and speech problems in daily life after chemoradiation for head and neck cancer based on cut-off scores of the patient-reported outcome measures SWAL-QOL and SHI.

    PubMed

    Rinkel, Rico N; Verdonck-de Leeuw, Irma M; Doornaert, Patricia; Buter, Jan; de Bree, Remco; Langendijk, Johannes A; Aaronson, Neil K; Leemans, C René

    2016-07-01

    The objective of this study is to assess swallowing and speech outcome after chemoradiation therapy for head and neck cancer, based on the patient-reported outcome measures Swallowing Quality of Life Questionnaire (SWAL-QOL) and Speech Handicap Index (SHI), both provided with cut-off scores. This is a cross-sectional study. Department of Otolaryngology/Head and Neck Surgery of a University Medical Center. Sixty patients, 6 months to 5 years after chemoradiation for head and neck squamous cell carcinoma. Swallowing Quality of Life Questionnaire (SWAL-QOL) and SHI, both validated in Dutch and provided with cut-off scores. Associations were tested between the outcome measures and independent variables (age, gender, tumor stage and site, and radiotherapy technique, time since treatment, comorbidity and food intake). Fifty-two patients returned the SWAL-QOL and 47 the SHI (response rate 87 and 78 %, respectively). Swallowing and speech problems were present in 79 and 55 %, respectively. Normal food intake was noticed in 45, 35 % had a soft diet and 20 % tube feeding. Patients with soft diet and tube feeding reported more swallowing problems compared to patients with normal oral intake. Tumor subsite was significantly associated with swallowing outcome (less problems in larynx/hypopharynx compared to oral/oropharynx). Radiation technique was significantly associated with psychosocial speech problems (less problems in patients treated with IMRT). Swallowing and (to a lesser extent) speech problems in daily life are frequently present after chemoradiation therapy for head and neck cancer. Future prospective studies will give more insight into the course of speech and swallowing problems after chemoradiation and into efficacy of new radiation techniques and swallowing and speech rehabilitation programs.

  1. Diagnostic and prognostic value of brain natriuretic peptide (BNP) concentrations in very elderly heart disease patients: specific geriatric cut-off and impacts of age, gender, renal dysfunction, and nutritional status.

    PubMed

    Blondé-Cynober, F; Morineau, G; Estrugo, B; Fillie, E; Aussel, C; Vincent, J-P

    2011-01-01

    Confirming the presence of heart failure (HF) in geriatric patients is made difficult by the overlapping symptoms with other diseases and by limited access to investigative techniques such as echography, and the clinical signs are either non-constant or difficult to interpret. In this context, BNP measurement could prove highly useful. We determined a cut-off value of BNP for diagnosing HF in geriatric patients and gauged its predictive power in terms of cardiovascular events, dependence and death within a 6-month timeframe. This clinical and biological study was performed in patients, 44 women and 20 men, age>65 years with suspected HF hospitalized in the geriatric unit at Emile-Roux hospital. Echography was performed at baseline examination. BNP concentrations were determined at baseline examination and at 2 and 6 months later. Renal function was assessed via the Cockroft-Gault formula. Nutritional status was assessed using the geriatric nutritional risk index (GNRI). Final reference diagnosis was established by both cardiologist and geriatrician. The diagnostic value of BNP was assessed by area under the ROC curve. The average age of the 64 patients was 84.3±7.4 years. The final diagnosis was HF in 26 patients (41%). A BNP<129pg/ml had a negative predictive value of 90% (accuracy 80%) for excluding the diagnosis of HF. BNP values were predictive of cardiovascular events over a 2-month timeframe in patients with HF and over a 6-month timeframe in the global population. BNP values were not predictive of mortality in patients with or without HF. BNP testing should help to differentiate pulmonary from cardiac etiologies of dyspnea, but a specific cut-off point has to be used in geriatric settings, mainly for patients presenting nutritional and renal dysfunctions.

  2. Persistently anomalous Pacific geomagnetic fields

    NASA Astrophysics Data System (ADS)

    Johnson, Catherine L.; Constable, Catherine G.

    A new average geomagnetic field model for the past 3kyr (ALS3K) helps bridge a large temporal sampling gap between historical models and more traditional paleomagnetic studies spanning the last 5 Myr. A quasi-static feature seen historically in the central Pacific has the opposite sign in ALS3K; its structure is similar to, but of larger amplitude than, that in the time-averaged geomagnetic field for the last 5 Myr. Anomalous geomagnetic fields exist beneath the Pacific over timescales ranging from 10²-106 years. It is unlikely that bias over such long time scales arises from electromagnetic screening, but conceivable that the Lorentz force is influenced by long wavelength thermal variations and/or localized regions of increased electrical conductivity (associated with compositional anomalies and possibly partial melt). This is consistent with recent seismic observations of the lower mantle.

  3. Solar Influences on Geomagnetic and Related Phenomena

    NASA Technical Reports Server (NTRS)

    Vestine, E. H.

    1961-01-01

    A discussion of the geomagnetic effects of streams of electromagnetic and particular radiation from the sun. The interplay of forces between the geomagnetic field and solar streams is outlined; and the theoretical relationship between these, the solar storms, the trapped Van Allen radiations, the polar aurora, and geomagnetic field distortion are presented.

  4. Geomagnetic response to solar activity.

    NASA Technical Reports Server (NTRS)

    Mead, G. D.

    1972-01-01

    The relationship between solar activity and geomagnetic variations is discussed in the light of spacecraft data obtained during the last decade. The effects of centers of solar activity responsible for producing geomagnetic activity on earth are believed to be transmitted through the solar wind, and there is usually a delay of two or three days before the onset of magnetic activity. Attempts to make a one-to-one correspondence between specific solar events and specific magnetic storms, however, are usually unsuccessful, because of the complex and indirect processes linking the two phenomena. Normally, only statistical tendencies can be shown.

  5. On Geomagnetism and Paleomagnetism

    NASA Technical Reports Server (NTRS)

    Voorhies, Coerte V.

    1998-01-01

    A statistical description of Earth's broad scale, core-source magnetic field has been developed and tested. The description features an expected, or mean, spatial magnetic power spectrum that is neither "flat" nor "while" at any depth, but is akin to spectra advanced by Stevenson and McLeod. This multipole spectrum describes the magnetic energy range; it is not steep enough for Gubbins' magnetic dissipation range. Natural variations of core multipole powers about their mean values are to be expected over geologic time and are described via trial probability distribution functions that neither require nor prohibit magnetic isotropy. The description is thus applicable to core-source dipole and low degree non-dipole fields despite axial dipole anisotropy. The description is combined with main field models of modem satellite and surface geomagnetic measurements to make testable predictions of: (1) the radius of Earth's core, (2) mean paleomagnetic field intensity, and (3) the mean rates and durations of both dipole power excursions and durable axial dipole reversals. The predicted core radius is 0.7% above the 3480 km seismologic value. The predicted root mean square paleointensity (35.6 mu T) and mean Virtual Axial Dipole Moment (about 6.2 lx 1022 Am(exp 2)) are within the range of various mean paleointensity estimates. The predicted mean rate of dipole power excursions, as defined by an absolute dipole moment <20% of the 1980 value, is 9.04/Myr and 14% less than obtained by analysis of a 4 Myr paleointensity record. The predicted mean rate of durable axial dipole reversals (2.26/Myr) is 2.3% more than established by the polarity time-scale for the past 84 Myr. The predicted mean duration of axial dipole reversals (5533 yr) is indistinguishable from an observational value. The accuracy of these predictions demonstrates the power and utility of the description, which is thought to merit further development and testing. It is suggested that strong stable stratification

  6. Rigid-Rod Polyimides

    NASA Technical Reports Server (NTRS)

    Chuang, Kathy C.; Kinder, James D.; Hull, Diana L.; Youngs, Wiley J.

    1996-01-01

    Experimental polyimides relatively rigid synthesized in effort to exploit some of advantages of rodlike polymers, while alleviating disadvantages. Polymers used to make colorless fibers and transparent films for optical and electronic application.

  7. The limitations of using vertical cutoff rigidities determined from the IGRF magnetic field models for computing aircraft radiation dose.

    PubMed

    Smart, D F; Shea, M A

    2003-01-01

    Vertical cutoff rigidities derived from the International Geomagnetic Reference Fields (IGRF) are normally used to compute the radiation dose at a specific location and to organize the radiation dose measurements acquired at aircraft altitudes. This paper presents some of the usually ignored limits on the accuracy of the vertical cutoff rigidity models and describes some of the computational artifacts present in these models. It is noted that recent aircraft surveys of the radiation dose experienced along specific flight paths is sufficiently precise that the secular variation of the geomagnetic field is observable.

  8. Colonoscope flexural rigidity measurement.

    PubMed

    Wehrmeyer, J A; Barthel, J A; Roth, J P; Saifuddin, T

    1998-07-01

    A testing device is developed that determines the stiffness, or flexural rigidity, of an endoscope at specific locations down its length by subjecting it to a compressive axial force, a situation similar to the actual forces applied to the endoscope during a clinical procedure. The endoscope is made to deform in a similar fashion to a slender buckled column and the force causing this deformation is related to the flexural rigidity using column buckling theory. A direct relationship between the critical load needed to cause buckling and the square of column length L is demonstrated experimentally and is expected theoretically, giving confidence in the application of column buckling theory to endoscope testing. Additional confidence in the validity of the column buckling test results is obtained by their similarity to data obtained by subjecting the endoscope to a transverse load, determining deflection, and modelling the endoscope as a bent elastic beam. Several makes and models of endoscopes were tested, with flexural rigidity values typically ranging between 160 to 240 Ncm2. The effect of a metal stiffener inserted in an endoscope's accessory channel is quantified, as is the change in flexural rigidity down the insertion shaft of a graded-stiffness endoscope. Significant differences in flexural rigidity were obtained between identical endoscopes, each sharing similar usage histories, indicating the need for flexural rigidity measurements for each individual endoscope of a particular model line, though a more extensive study is required to reliably determine scope-to-scope stiffness variations for a particular model line.

  9. Klimovskaya: A new geomagnetic observatory

    NASA Astrophysics Data System (ADS)

    Soloviev, A. A.; Sidorov, R. V.; Krasnoperov, R. I.; Grudnev, A. A.; Khokhlov, A. V.

    2016-05-01

    In 2011 Geophysical Center RAS (GC RAS) began to deploy the Klimovskaya geomagnetic observatory in the south of Arkhangelsk region on the territory of the Institute of Physiology of Natural Adaptations, Ural Branch, Russian Academy of Sciences (IPNA UB RAS). The construction works followed the complex of preparatory measures taken in order to confirm that the observatory can be constructed on this territory and to select the optimal configuration of observatory structures. The observatory equipping stages are described in detail, the technological and design solutions are described, and the first results of the registered data quality control are presented. It has been concluded that Klimovskaya observatory can be included in INTERMAGNET network. The observatory can be used to monitor and estimate geomagnetic activity, because it is located at high latitudes and provides data in a timely manner to the scientific community via the web-site of the Russian-Ukrainian Geomagnetic Data Center. The role of ground observatories such as Klimovskaya remains critical for long-term observations of secular variation and for complex monitoring of the geomagnetic field in combination with low-orbiting satellite data.

  10. Johann von Lamont: A Pioneer in Geomagnetism

    NASA Astrophysics Data System (ADS)

    Soffel, Heinrich

    2006-06-01

    The 200th birthday of John Lamont (1805-1879, Figure 1), a pioneer in the study of geomagnetism, was marked on 13 December 2005. Lamont founded the Munich Geomagnetic Observatory in 1840 and was a member of the group of scientists including Carl Friedrich Gauss, Alexander von Humboldt, Eduard Sabine, Jonas Angstrøm, Humphret Lloyd, Adolf Kupffer, Karl Kreil, and Adolphe Quetelet who composed the Göttingen Magnetic Union. They organized an international network of geomagnetic observatories [Barraclough et al., 1992]. The present knowledge of the geomagnetic field and its secular variation is largely based on the data collected by the global network of geomagnetic observatories during the last 170 years. Lamont's talents and his dedication and enthusiasm for discovery are reflected in the depth and scope of his contributions to a broad variety of natural sciences such as astronomy, meteorology, geomagnetism, and geodesy. However, this article just touches on his merits in geomagnetism.

  11. Extreme Geomagnetic Storms - 1868 - 2010

    NASA Astrophysics Data System (ADS)

    Vennerstrom, S.; Lefevre, L.; Dumbović, M.; Crosby, N.; Malandraki, O.; Patsou, I.; Clette, F.; Veronig, A.; Vršnak, B.; Leer, K.; Moretto, T.

    2016-05-01

    We present the first large statistical study of extreme geomagnetic storms based on historical data from the time period 1868 - 2010. This article is the first of two companion papers. Here we describe how the storms were selected and focus on their near-Earth characteristics. The second article presents our investigation of the corresponding solar events and their characteristics. The storms were selected based on their intensity in the aa index, which constitutes the longest existing continuous series of geomagnetic activity. They are analyzed statistically in the context of more well-known geomagnetic indices, such as the Kp and Dcx/Dst index. This reveals that neither Kp nor Dcx/Dst provide a comprehensive geomagnetic measure of the extreme storms. We rank the storms by including long series of single magnetic observatory data. The top storms on the rank list are the New York Railroad storm occurring in May 1921 and the Quebec storm from March 1989. We identify key characteristics of the storms by combining several different available data sources, lists of storm sudden commencements (SSCs) signifying occurrence of interplanetary shocks, solar wind in-situ measurements, neutron monitor data, and associated identifications of Forbush decreases as well as satellite measurements of energetic proton fluxes in the near-Earth space environment. From this we find, among other results, that the extreme storms are very strongly correlated with the occurrence of interplanetary shocks (91 - 100 %), Forbush decreases (100 %), and energetic solar proton events (70 %). A quantitative comparison of these associations relative to less intense storms is also presented. Most notably, we find that most often the extreme storms are characterized by a complexity that is associated with multiple, often interacting, solar wind disturbances and that they frequently occur when the geomagnetic activity is already elevated. We also investigate the semiannual variation in storm occurrence

  12. Teaching Geomagnetism in High School

    NASA Astrophysics Data System (ADS)

    Stern, D. P.

    2001-05-01

    Many high school curricula include a one-year course in Earth Sciences, often in the 9th grade (essentially pre-algebra). That is a good time to teach about geomagnetism. Not only are dipole reversals and sea-floor magnetization central to this subject, but this is a good opportunity to introduce students to magnetism and its connection to electric currents. The story of Oersted and Faraday give a fascinating insight into the uneven path of scientific discovery, the magnetic compass and William Gilbert provide a view of the beginnings of the scientific revolution, and even basic concepts of dynamo theory and its connection to solar physics can be included. A resource including all the suitable material now exists on the world-wide web at http://www-spof.gsfc.nasa.gov/earthmag/demagint.htm (home page). A 1-month unit on geomagnetism will be outlined.

  13. Ice ages and geomagnetic reversals

    NASA Technical Reports Server (NTRS)

    Wu, Patrick

    1992-01-01

    There have been speculations on the relationship between climatic cooling and polarity reversals of the earth's magnetic field during the Pleistocene. Two of the common criticisms on this relationship have been the reality of these short duration geomagnetic events and the accuracy of their dates. Champion et al. (1988) have reviewed recent progress in this area. They identified a total of 10 short-duration polarity events in the last 1 Ma and 6 of these events have been found in volcanic rocks, which also have K-Ar dates. Supposing that the speculated relationship between climatic cooling and geomagnetic reversals actually exist, two mechanisms that assume climatic cooling causes short period magnetic reversals will be investigated. These two methods are core-mantle boundary topography and transfer of the rotational energy to the core.

  14. Correlative comparison of geomagnetic storms and auroral substorms using geomagnetic indeces. Master's thesis

    SciTech Connect

    Cade, W.B.

    1993-06-01

    Partial contents include the following: (1) Geomagnetic storm and substorm processes; (2) Magnetospheric structure; (3) Substorm processes; (4) Data description; (5) Geomagnetic indices; and (6) Data period and data sets.

  15. Rigid lenses: an overview.

    PubMed

    Bayshore, C A

    1979-03-01

    New gas permeable rigid contact lens materials, by allowing direct transmission of oxygen, provide significant advantages over PMMA. Edema resulting from oxygen deprivation with PMMA lenses is eliminated and comfort is increased. Three types of gas permeable materials are described: CAB, silicone, and a combination of CAB and silicone.

  16. Electrostatics of Rigid Polyelectrolytes

    SciTech Connect

    Wong, G.C.L.

    2009-06-04

    The organization of rigid biological polyelectrolytes by multivalent ions and macroions are important for many fundamental problems in biology and biomedicine, such as cytoskeletal regulation and antimicrobial sequestration in cystic fibrosis. These polyelectrolytes have been used as model systems for understanding electrostatics in complex fluids. Here, we review some recent results in theory, simulations, and experiments.

  17. Rigid molecular foams

    SciTech Connect

    Steckle, W.P. Jr.; Mitchell, M.A.; Aspen, P.G.

    1998-12-31

    This is the final report of a three-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). Organic analogues to inorganic zeolites would be a significant step forward in engineered porous materials and would provide advantages in range, selectivity, tailorability, and processing. Rigid molecular foams or {open_quotes}organic zeolites{close_quotes} would not be crystalline materials and could be tailored over a broader range of pore sizes and volumes. A novel process for preparing hypercrosslinked polymeric foams has been developed via a Friedel-Crafts polycondensation reaction. A series of rigid hypercrosslinked foams have been prepared using simple rigid polyaromatic hydrocarbons including benzene, biphenyl, m-terphenyl, diphenylmethane, and polystyrene, with dichloroxylene (DCX) as the pore size. After drying the foams are robust and rigid. Densities of the resulting foams can range from 0.15 g/cc to 0.75 g/cc. Nitrogen adsorption studies have shown that by judiciously selecting monomers and the crosslinking agent along with the level of crosslinking and the cure time of the resulting gel, the pore size, pore size distribution, and the total surface area of the foam can be tailored. Surface areas range from 160 to 1,200 m{sup 2}/g with pore sizes ranging from 6 {angstrom} to 2,000 {angstrom}.

  18. Geomagnetic effects caused by rocket exhaust jets

    NASA Astrophysics Data System (ADS)

    Lipko, Yuriy; Pashinin, Aleksandr; Khakhinov, Vitaliy; Rahmatulin, Ravil

    2016-09-01

    In the space experiment Radar-Progress, we have made 33 series of measurements of geomagnetic variations during ignitions of engines of Progress cargo spacecraft in low Earth orbit. We used magneto-measuring complexes, installed at observatories of the Institute of Solar-Terrestrial Physics of Siberian Branch of the Russian Academy of Sciences, and magnetotelluric equipment of a mobile complex. We assumed that engine running can cause geomagnetic disturbances in flux tubes crossed by the spacecraft. When analyzing experimental data, we took into account space weather factors: solar wind parameters, total daily mid-latitude geomagnetic activity index Kp, geomagnetic auroral electrojet index AE, global geomagnetic activity. The empirical data we obtained indicate that 18 of the 33 series showed geomagnetic variations in various time ranges.

  19. Extracorporeal light chain elimination: high cut-off (HCO) hemodialysis parallel to chemotherapy allows for a high proportion of renal recovery in multiple myeloma patients with dialysis-dependent acute kidney injury.

    PubMed

    Heyne, Nils; Denecke, Barbara; Guthoff, Martina; Oehrlein, Katharina; Kanz, Lothar; Häring, Hans-Ulrich; Weisel, Katja C

    2012-05-01

    Acute kidney injury (AKI) is frequent in multiple myeloma (MM) patients and strongly affects prognosis, with particularly poor outcomes in patients requiring hemodialysis. Introduction of the novel therapeutic agents to MM therapy has improved myeloma response and renal outcome. This case series reviews the efficacy of combined systemic and extracorporeal therapy to further optimize time to light chain (serum-free light chain (sFLC)) reduction and renal recovery in MM patients with dialysis-dependent AKI (n = 19). High cut-off (HCO) hemodialysis for extracorporeal sFLC removal was initiated in parallel to chemotherapy. Combined therapy resulted in early sFLC response after a median of 13 (range 4-48) days and 6 (3-22) HCO hemodialysis sessions. Time to sFLC response was shorter in patients recovering renal function. Median time to dialysis independence was 15 (4-64) days. By intent-to-treat analysis, sustained renal recovery was achieved in 73.7% (77.8% adjusted for death) of patients. In multivariate analysis, duration of AKI prior to initiation of therapy was an independent predictor of renal functional outcome. Combining HCO hemodialysis for extracorporeal sFLC elimination and effective chemotherapy is a novel treatment strategy allowing for early and sustained sFLC reduction and a high proportion of renal recovery in these patients. Timely diagnosis and onset of therapy is essential for improving renal outcome.

  20. Pressurized liquid extraction for the determination of cannabinoids and metabolites in hair: Detection of cut-off values by high performance liquid chromatography-high resolution tandem mass spectrometry.

    PubMed

    Montesano, Camilla; Simeoni, Maria Chiara; Vannutelli, Gabriele; Gregori, Adolfo; Ripani, Luigi; Sergi, Manuel; Compagnone, Dario; Curini, Roberta

    2015-08-07

    Hair analysis has become a routine procedure in most forensic laboratories since this alternative matrix presents clear advantages over classical matrices; particularly wider time window, non-invasive sampling and good stability of the analytes over time. There are, however, some major challenges for the analysis of cannabinoids in hair, mainly related to the low concentrations of 11-nor-9-carboxy-Δ(9)-tetrahydrocannabinol (THC-COOH), that is the major metabolite. In this study a fast, accurate and sensitive method for the determination of cannabinol, cannabidiol, THC and THC-COOH in hair has been developed. The extraction of analytes from hair (50mg) is based on an automated pressurized liquid extraction (PLE) using water modified with the surfactant sodium dodecyl sulphate as eluent phase. PLE extract is then cleaned up by SPE using polymeric reversed phase cartridges Strata XL before the injection in the HPLC-HRMS/MS system. Chromatographic conditions obtained with a fused-core column allowed a good separation of the analytes in less than 4min. The whole procedure has been validated according to SWGTOX guidelines. The LLOQs obtained for THC-COOH and the other analytes were respectively 0.1 and 2pg/mg. To the best of our knowledge, this is the first LC-MS/MS based method that allows the detection of THC-COOH in hair at values lower than the cut-off.

  1. Restoration project of geomagnetic survey in Latvia

    NASA Astrophysics Data System (ADS)

    Burlakovs, J.; Lembere, I.

    2003-04-01

    THE RESTORATION PROJECT OF GEOMAGNETIC SURVEY IN LATVIA J. Burlakovs, I. Lembere State Land Service of Latvia, Geodesy Board juris.burlakovs@gp.vzd.gov.lv / Fax: +371-7612736 The aim of geomagnetic survey measurements is to study the geomagnetic field at global, regional as well as local scales. To determine secular changes of the geomagnetic field it is very important to do a lot of regular field work. Recalculation and comparison of measured data for corrections must be made using the observatory or magnetic station data collected nearby the investigated area in the real-time. Field geomagnetic survey measurements in Latvia have not been made since 1991. The State Land Service of Latvia, the Geodesy Board plans to restart such kind of measurements in Latvia. The repeat station network must be renewed, regular magnetic declination, inclination and total field intensity data must be gathered, compared with the observatory data and secular changes of the geomagnetic field discovered. It is also possible to do regional correlations for data to determine future trends of the geomagnetic field changes. The detection of geomagnetic anomalies and the reason of the existence of those at particular territories could be made. Such kind of measurements demands the highest accuracy and therefore is necessary to cooperate with geomagnetic research network groups in neighbouring areas - Estonia, Finland and Poland, where permanent magnetic stations are situated. One permanent magnetic station also could be established in Latvia to do permanent recordings of geomagnetic field components, which give the possibility to do regional corrections for separate measurement recordings in the field. Geomagnetic field studies are important for cartography, navigational and military needs, also it is possible to use this information together with geological and geophysical data to create and specify the geological model for the territory. In future Latvia must participate within the

  2. The Geomagnetic Field During a Reversal

    NASA Technical Reports Server (NTRS)

    Heirtzler, James R.

    2003-01-01

    By modifying the IGRF it is possible to learn what may happen to the geomagnetic field during a geomagnetic reversal. If the entire IGRF reverses then the declination and inclination only reverse when the field strength is zero. If only the dipole component of the IGRF reverses a large geomagnetic field remains when the dipole component is zero and he direction of the field at the end of the reversal is not exactly reversed from the directions at the beginning of the reversal.

  3. New book discusses normal geomagnetic field

    SciTech Connect

    Pochtarev, V.I.

    1984-07-01

    Material on the normal geomagnetic field and its gradients over the Earth's surface at different elevations is presented. Methods are developed for plotting the normal geomagnetic field and mathematical approximations of the geomagnetic field are presented. The nature of the Earth's normal magnetic field is investigated on the basis of an analysis of geophysical, geological and geochemical data and data on the internal structure of the Earth.

  4. The Causes of Geomagnetic Storms During Solar Maximum

    NASA Technical Reports Server (NTRS)

    Tsurutani, B. T.; Gonzalez, W. D.

    1998-01-01

    One of the oldest mysteries in geomagnetism is the linkage between solar and geomagnetic activity. The 11-year cycles of both the numbers of sunspots and Earth geomagnetic storms were first noted by Sabine (1852).

  5. Obituary--rigid contact lenses.

    PubMed

    Efron, Nathan

    2010-10-01

    Scleral and corneal rigid lenses represented 100 per cent of the contact lens market immediately prior to the invention of soft lenses in the mid-1960s. In the United Kingdom today, rigid lenses comprise 2 per cent of all new lens fits. Low rates of rigid lens fitting are also apparent in 27 other countries which have recently been surveyed. Thus, the 1998 prediction of the author that rigid lenses--also referred to as 'rigid gas permeable' (RGP) lenses or 'gas permeable' (GP) lenses--would be obsolete by the year 2010 has essentially turned out to be correct. In this obituary, the author offers 10 reasons for the demise of rigid lens fitting: initial rigid lens discomfort; intractable rigid lens-induced corneal and lid pathology; extensive soft lens advertising; superior soft lens fitting logistics; lack of rigid lens training opportunities; redundancy of the rigid lens 'problem solver' function; improved soft toric and bifocal/varifocal lenses; limited uptake of orthokeratology; lack of investment in rigid lenses; and the emergence of aberration control soft lenses. Rigid lenses are now being fitted by a minority of practitioners with specialist skills/training. Certainly, rigid lenses can no longer be considered as a mainstream form of contact lens correction. May their dear souls (bulk properties) rest in peace.

  6. Sparkling Geomagnetic Field: Involving Schools in Geomagnetic Research

    NASA Astrophysics Data System (ADS)

    Bailey, Rachel; Leonhardt, Roman; Leichter, Barbara

    2014-05-01

    Solar activity will be reaching a maximum in 2013/2014 as the sun reaches the end of its cycle, bringing with it an opportunity to study in greater detail the effect of solar wind or "space weather" on our planet's magnetic field. Heightened solar activity leads to a larger amount of clouds of energetic particles bombarding the Earth. Although the Earth's magnetic field shields us from most of these particles, the field becomes distorted and compacted by the solar wind, which leads to magnetic storms that we detect from the surface. These storms cause aurorae at higher latitudes and can lead to widespread disruption of communication and navigation equipment all over the Earth when sufficiently strong. This project, "Sparkling Geomagnetic Field," is a part of Austria's Sparkling Science programme, which aims to involve schools in active scientific research to encourage interest in science from a young age. Researchers from the Central Institute for Meteorology and Geodynamics (ZAMG) in Vienna have worked hand-in-hand with three schools across Austria to set up regional geomagnetic stations consisting of state-of-the-art scalar and vector magnetometers to monitor the effects of the solar wind on the geomagnetic field. The students have been an active part of the research team from the beginning, first searching for a suitable location to set up the stations as well as later overseeing the continued running of the equipment and analysing the data output. Through this project the students will gain experience in contemporary scientific methods: data processing and analysis, field work, as well as equipment setup and upkeep. A total of three stations have been established with schools in Innsbruck, Tamsweg and Graz at roughly equal distances across Austria to run alongside the already active station in the Conrad Observatory near Vienna. Data acquisition runs through a data logger and software developed to deliver data in near realtime. This network allows for

  7. How rigid are viruses

    NASA Astrophysics Data System (ADS)

    Hartschuh, R. D.; Wargacki, S. P.; Xiong, H.; Neiswinger, J.; Kisliuk, A.; Sihn, S.; Ward, V.; Vaia, R. A.; Sokolov, A. P.

    2008-08-01

    Viruses have traditionally been studied as pathogens, but in recent years they have been adapted for applications ranging from drug delivery and gene therapy to nanotechnology, photonics, and electronics. Although the structures of many viruses are known, most of their biophysical properties remain largely unexplored. Using Brillouin light scattering, we analyzed the mechanical rigidity, intervirion coupling, and vibrational eigenmodes of Wiseana iridovirus (WIV). We identified phonon modes propagating through the viral assemblies as well as the localized vibrational eigenmode of individual viruses. The measurements indicate a Young’s modulus of ˜7GPa for single virus particles and their assemblies, surprisingly high for “soft” materials. Mechanical modeling confirms that the DNA core dominates the WIV rigidity. The results also indicate a peculiar mechanical coupling during self-assembly of WIV particles.

  8. Dynamic rigidity transition

    NASA Astrophysics Data System (ADS)

    Åström, J. A.; Latva-Kokko, M.; Timonen, J.

    2003-01-01

    An inflated closed loop (or membrane) is used to demonstrate a dynamic rigidity transition that occurs when impact energy is added to the loop in static equilibrium at zero temperature. The only relevant parameter in this transition is the ratio of the energy needed to collapse the loop and the impact energy. When this ratio is below a threshold value close to unity, the loop collapses into a high-entropy floppy state, and it does not return to the rigid state unless the impact energy can escape. The internal oscillations are in the floppy state dominated by 1/f2 noise. When the ratio is above the threshold, the loop does not collapse, and the internal oscillations resulting from the impact are dominated by the eigenfrequencies of the stretched membrane. In this state, the loop can bounce for a long time. It is still an open question whether bouncing will eventually vanish or whether a stationary bouncing state will be reached. The dynamic transition between the floppy and the rigid state is discontinuous.

  9. Electric utility industry experience with geomagnetic disturbances

    SciTech Connect

    Barnes, P.R.; Rizy, D.T.; McConnell, B.W. ); Taylor, E.R. Jr. ); Tesche, F.M.

    1991-09-01

    A geomagnetic disturbance (GMD) by its nature occurs globally and almost simultaneously. Severe geomagnetic storms cause problems for electric power systems. The vulnerability of electric power systems to such events has apparently increased during the last 10 to 20 years because power system transmission lines have become more interconnected and have increased in length and because power systems are now operated closer to their limits than in the past. In this report, the experience of electric utilities during geomagnetic storms is examined and analyzed. Measured data, effects on power system components, and power system impacts are considered. It has been found that electric power systems are susceptible to geomagnetically induced earth-surface potential gradients as small as few (2 to 3) volts per kilometer, corresponding to a storm of K-6 intensity over an area of high earth resistivity. The causes and effects are reasonably well understood, but additional research is needed to develop a better understanding of solar-induced geomagnetic storms and the responses of power systems to these types of storms. A better understanding of geomagnetic storms and the power systems' responses to GMDs is needed so that mitigation measures can be implemented that will make power systems less susceptible to severe geomagnetic disturbances. A GMD caused by a large high-altitude nuclear detonation is similar in many ways to that of solar-induced geomagnetic storms except that a nuclear-caused disturbance would be much more intense with a far shorter duration. 49 refs.

  10. Electric Utility Industry Experience with Geomagnetic Disturbances

    SciTech Connect

    Barnes, P.R.

    1991-01-01

    A geomagnetic disturbance (GMD) by its nature occurs globally and almost simultaneously. Severe geomagnetic storms cause problems for electric power systems. The vulnerability of electric power systems to such events has apparently increased during the last 10 to 20 years because power system transmission lines have become more interconnected and have increased in length and because power systems are now operated closer to their limits than in the past. In this report, the experience of electric utilities during geomagnetic storms is examined and analyzed. Measured data, effects on power system components, and power system impacts are considered. It has been found that electric power systems are susceptible to geomagnetically induced earth-surface potential gradients as small as a few (2 to 3) volts per kilometer, corresponding to a storm of K-6 intensity over an area of high earth resistivity. The causes and effects are reasonably well understood, but additional research is needed to develop a better understanding of solar-induced geomagnetic storms and the responses of power systems to these types of storms. A better understanding of geomagnetic storms and the power systems' responses to GMDs is needed so that mitigation measures can be implemented that will make power systems less susceptible to severe geomagnetic disturbances. A GMD caused by a large high-altitude nuclear detonation is similar in many ways to that of solar-induced geomagnetic storms except that a nuclear-caused disturbance would be much more intense with a far shorter duration.

  11. Electric utility industry experience with geomagnetic disturbances

    SciTech Connect

    Barnes, P.R.; Rizy, D.T.; McConnell, B.W.; Taylor, E.R. Jr.; Tesche, F.M.

    1991-09-01

    A geomagnetic disturbance (GMD) by its nature occurs globally and almost simultaneously. Severe geomagnetic storms cause problems for electric power systems. The vulnerability of electric power systems to such events has apparently increased during the last 10 to 20 years because power system transmission lines have become more interconnected and have increased in length and because power systems are now operated closer to their limits than in the past. In this report, the experience of electric utilities during geomagnetic storms is examined and analyzed. Measured data, effects on power system components, and power system impacts are considered. It has been found that electric power systems are susceptible to geomagnetically induced earth-surface potential gradients as small as few (2 to 3) volts per kilometer, corresponding to a storm of K-6 intensity over an area of high earth resistivity. The causes and effects are reasonably well understood, but additional research is needed to develop a better understanding of solar-induced geomagnetic storms and the responses of power systems to these types of storms. A better understanding of geomagnetic storms and the power systems` responses to GMDs is needed so that mitigation measures can be implemented that will make power systems less susceptible to severe geomagnetic disturbances. A GMD caused by a large high-altitude nuclear detonation is similar in many ways to that of solar-induced geomagnetic storms except that a nuclear-caused disturbance would be much more intense with a far shorter duration. 49 refs.

  12. A proteinuria cut-off level of 0.7 g/day after 12 months of treatment best predicts long-term renal outcome in lupus nephritis: data from the MAINTAIN Nephritis Trial

    PubMed Central

    Tamirou, Farah; Lauwerys, Bernard R; Dall'Era, Maria; Mackay, Meggan; Rovin, Brad; Cervera, Ricard; Houssiau, Frédéric A

    2015-01-01

    Background Although an early decrease in proteinuria has been correlated with good long-term renal outcome in lupus nephritis (LN), studies aimed at defining a cut-off proteinuria value are missing, except a recent analysis performed on patients randomised in the Euro-Lupus Nephritis Trial, demonstrating that a target value of 0.8 g/day at month 12 optimised sensitivity and specificity for the prediction of good renal outcome. The objective of the current work is to validate this target in another LN study, namely the MAINTAIN Nephritis Trial (MNT). Methods Long-term (at least 7 years) renal function data were available for 90 patients randomised in the MNT. Receiver operating characteristic curves were built to test the performance of proteinuria measured within the 1st year as short-term predictor of long-term renal outcome. We calculated the positive and negative predictive values (PPV, NPV). Results After 12 months of treatment, achievement of a proteinuria <0.7 g/day best predicted good renal outcome, with a sensitivity and a specificity of 71% and 75%, respectively. The PPV was high (94%) but the NPV low (29%). Addition of the requirement of urine red blood cells ≤5/hpf as response criteria at month 12 reduced sensitivity from 71% to 41%. Conclusions In this cohort of mainly Caucasian patients suffering from a first episode of LN in most cases, achievement of a proteinuria <0.7 g/day at month 12 best predicts good outcome at 7 years and inclusion of haematuria in the set of criteria at month 12 undermines the sensitivity of early proteinuria decrease for the prediction of good outcome. The robustness of these conclusions stems from the very similar results obtained in two distinct LN cohorts. Trial registration number: NCT00204022. PMID:26629352

  13. Electrochemical performance of a nickel-rich LiNi0.6Co0.2Mn0.2O2 cathode material for lithium-ion batteries under different cut-off voltages

    NASA Astrophysics Data System (ADS)

    Cheng, Kai-lin; Mu, Dao-bin; Wu, Bo-rong; Wang, Lei; Jiang, Ying; Wang, Rui

    2017-03-01

    A spherical-like Ni0.6Co0.2Mn0.2(OH)2 precursor was tuned homogeneously to synthesize LiNi0.6Co0.2Mn0.2O2 as a cathode material for lithium-ion batteries. The effects of calcination temperature on the crystal structure, morphology, and the electrochemical performance of the as-prepared LiNi0.6Co0.2Mn0.2O2 were investigated in detail. The as-prepared material was characterized by X-ray diffraction, scanning electron microscopy, laser particle size analysis, charge-discharge tests, and cyclic voltammetry measurements. The results show that the spherical-like LiNi0.6Co0.2Mn0.2O2 material obtained by calcination at 900°C displayed the most significant layered structure among samples calcined at various temperatures, with a particle size of approximately 10 μm. It delivered an initial discharge capacity of 189.2 mAh•g-1 at 0.2C with a capacity retention of 94.0% after 100 cycles between 2.7 and 4.3 V. The as-prepared cathode material also exhibited good rate performance, with a discharge capacity of 119.6 mAh•g-1 at 5C. Furthermore, within the cut-off voltage ranges from 2.7 to 4.3, 4.4, and 4.5 V, the initial discharge capacities of the calcined samples were 170.7, 180.9, and 192.8 mAh•g-1, respectively, at a rate of 1C. The corresponding retentions were 86.8%, 80.3%, and 74.4% after 200 cycles, respectively.

  14. Geomagnetic Disturbances Caused by Internal Atmospheric Dynamics

    NASA Technical Reports Server (NTRS)

    Sonneman, G.

    1984-01-01

    It is commonly believed that geomagnetic disturbances are caused by external influences connected with the solar wind. The 27-day recurrence of perturbations seems to be a strong hint for this interaction. But frequently geomagnetic disturbances occur without any relation to sunspot numbers or radiowave fluxes. This was one of the reasons for introducing hypothetical M-regions on the Sun and their relation to solar wind activities. Only one half of the variance of the geomagnetic AL-index could be related to the solar wind. Therefore it is concluded that internal processes of the magnetosphere were responsible for additional geomagnetic activity. Arguments, which might lead to the suggestion of geomagnetic disturbances as being caused by internal atmospheric dynamics are discussed and a rather preliminary scenario of those processes is proposed.

  15. History of the geomagnetic field

    USGS Publications Warehouse

    Doell, Richard R.

    1969-01-01

    Direct measurements of the direction and strength of the earth's magnetic field have provided a knowledge of the field's form and behavior during the last few hundreds of years. For older times, however, it has been necessary to measure the magnetism of certain rocks to learn what the geomagnetic field was like. For example, when a lava flow solidifies (at temperatures near 1000??C) and cools through the Curie point of the magnetic minerals contained in it (around 500??C) it acquires a remanent magnetism that is (1) very weak, (2) very stablel, (3) paralle to the direction of the ambient geomagnetic field, and (4) proportional in intensity to the ambient field. Separating, by various analytical means, this magnetization from other 'unwanted' magnetizations has allowed paleomagnetists to study the historical and prehistorical behavior of the earth's field. It has been learned, for example, that the strength of the field was almost twice its present value 2000 years ago and that it has often completely reversed its polarity. Paleo-magnetists have also confirmed that most oceans are, geologically speaking, relatively new features, and that the continents have markedly changed their positions over the surface of the earth. ?? 1969 The American Institute of Physics.

  16. Rigid porous filter

    DOEpatents

    Chiang, Ta-Kuan; Straub, Douglas L.; Dennis, Richard A.

    2000-01-01

    The present invention involves a porous rigid filter including a plurality of concentric filtration elements having internal flow passages and forming external flow passages there between. The present invention also involves a pressure vessel containing the filter for the removal of particulates from high pressure particulate containing gases, and further involves a method for using the filter to remove such particulates. The present filter has the advantage of requiring fewer filter elements due to the high surface area-to-volume ratio provided by the filter, requires a reduced pressure vessel size, and exhibits enhanced mechanical design properties, improved cleaning properties, configuration options, modularity and ease of fabrication.

  17. Birationally rigid Fano fibrations

    NASA Astrophysics Data System (ADS)

    Pukhlikov, A. V.

    2000-06-01

    We prove the birational superrigidity of a general Fano fibration \\pi\\colon V\\to\\mathbf P^1 whose fibre is a Fano hypersurface W_M\\subset\\mathbf P^M of index 1. If the fibration is sufficiently twisted over the base \\mathbf P^1, then V has no other structure of a fibration into rationally connected varieties. We also formulate and discuss conjectures on birational rigidity for a large class of Fano varieties and Fano fibrations over a base of arbitrary dimension.

  18. Improved geomagnetic referencing in the Arctic environment

    USGS Publications Warehouse

    Poedjono, B.; Beck, N.; Buchanan, A. C.; Borri, L.; Maus, S.; Finn, Carol; Worthington, Bill; White, Tim

    2016-01-01

    Geomagnetic referencing uses the Earth’s magnetic field to determine accurate wellbore positioning essential for success in today's complex drilling programs, either as an alternative or a complement to north-seeking gyroscopic referencing. However, fluctuations in the geomagnetic field, especially at high latitudes, make the application of geomagnetic referencing in those areas more challenging. Precise crustal mapping and the monitoring of real-time variations by nearby magnetic observatories is crucial to achieving the required geomagnetic referencing accuracy. The Deadhorse Magnetic Observatory (DED), located at Prudhoe Bay, Alaska, has already played a vital role in the success of several commercial ventures in the area, providing essential, accurate, real-time data to the oilfield drilling industry. Geomagnetic referencing is enhanced with real-time data from DED and other observatories, and has been successfully used for accurate wellbore positioning. The availability of real-time geomagnetic measurements leads to significant cost and time savings in wellbore surveying, improving accuracy and alleviating the need for more expensive surveying techniques. The correct implementation of geomagnetic referencing is particularly critical as we approach the increased activity associated with the upcoming maximum of the 11-year solar cycle. The DED observatory further provides an important service to scientific communities engaged in studies of ionospheric, magnetospheric and space weather phenomena.

  19. On the watch for geomagnetic storms

    USGS Publications Warehouse

    Green, Arthur W.; Brown, William M.

    1997-01-01

    Geomagnetic storms, induced by solar activity, pose significant hazards to satellites, electrical power distribution systems, radio communications, navigation, and geophysical surveys. Strong storms can expose astronauts and crews of high-flying aircraft to dangerous levels of radiation. Economic losses from recent geomagnetic storms have run into hundreds of millions of dollars. With the U.S. Geological Survey (USGS) as the lead agency, an international network of geomagnetic observatories monitors the onset of solar-induced storms and gives warnings that help diminish losses to military and commercial operations and facilities.

  20. Frequency of Proterozoic geomagnetic superchrons

    NASA Astrophysics Data System (ADS)

    Driscoll, Peter E.; Evans, David A. D.

    2016-03-01

    Long-term geodynamo evolution is expected to respond to inner core growth and changing patterns of mantle convection. Three geomagnetic superchrons, during which Earth's magnetic field maintained a near-constant polarity state through tens of Myr, are known from the bio/magnetostratigraphic record of Phanerozoic time, perhaps timed according to supercontinental episodicity. Some geodynamo simulations incorporating a much smaller inner core, as would have characterized Proterozoic time, produce field reversals at a much lower rate. Here we compile polarity ratios of site means within a quality-filtered global Proterozoic paleomagnetic database, according to recent plate kinematic models. Various smoothing parameters, optimized to successfully identify the known Phanerozoic superchrons, indicate 3-10 possible Proterozoic superchrons during the 1300 Myr interval studied. Proterozoic geodynamo evolution thus appears to indicate a relatively narrow range of reversal behavior through the last two billion years, implying either remarkable stability of core dynamics over this time or insensitivity of reversal rate to core evolution.

  1. Minimax confidence intervals in geomagnetism

    NASA Technical Reports Server (NTRS)

    Stark, Philip B.

    1992-01-01

    The present paper uses theory of Donoho (1989) to find lower bounds on the lengths of optimally short fixed-length confidence intervals (minimax confidence intervals) for Gauss coefficients of the field of degree 1-12 using the heat flow constraint. The bounds on optimal minimax intervals are about 40 percent shorter than Backus' intervals: no procedure for producing fixed-length confidence intervals, linear or nonlinear, can give intervals shorter than about 60 percent the length of Backus' in this problem. While both methods rigorously account for the fact that core field models are infinite-dimensional, the application of the techniques to the geomagnetic problem involves approximations and counterfactual assumptions about the data errors, and so these results are likely to be extremely optimistic estimates of the actual uncertainty in Gauss coefficients.

  2. Deciphering records of geomagnetic reversals

    NASA Astrophysics Data System (ADS)

    Valet, Jean-Pierre; Fournier, Alexandre

    2016-06-01

    Polarity reversals of the geomagnetic field are a major feature of the Earth's dynamo. Questions remain regarding the dynamical processes that give rise to reversals and the properties of the geomagnetic field during a polarity transition. A large number of paleomagnetic reversal records have been acquired during the past 50 years in order to better constrain the structure and geometry of the transitional field. In addition, over the past two decades, numerical dynamo simulations have also provided insights into the reversal mechanism. Yet despite the large paleomagnetic database, controversial interpretations of records of the transitional field persist; they result from two characteristics inherent to all reversals, both of which are detrimental to an ambiguous analysis. On the one hand, the reversal process is rapid and requires adequate temporal resolution. On the other hand, weak field intensities during a reversal can affect the fidelity of magnetic recording in sedimentary records. This paper is aimed at reviewing critically the main reversal features derived from paleomagnetic records and at analyzing some of these features in light of numerical simulations. We discuss in detail the fidelity of the signal extracted from paleomagnetic records and pay special attention to their resolution with respect to the timing and mechanisms involved in the magnetization process. Records from marine sediments dominate the database. They give rise to transitional field models that often lead to overinterpret the data. Consequently, we attempt to separate robust results (and their subsequent interpretations) from those that do not stand on a strong observational footing. Finally, we discuss new avenues that should favor progress to better characterize and understand transitional field behavior.

  3. Range indices of geomagnetic activity

    USGS Publications Warehouse

    Stuart, W.F.; Green, A.W.

    1988-01-01

    The simplest index of geomagnetic activity is the range in nT from maximum to minimum value of the field in a given time interval. The hourly range R was recommended by IAGA for use at observatories at latitudes greater than 65??, but was superceded by AE. The most used geomagnetic index K is based on the range of activity in a 3 h interval corrected for the regular daily variation. In order to take advantage of real time data processing, now available at many observatories, it is proposed to introduce a 1 h range index and also a 3 h range index. Both will be computed hourly, i.e. each will have a series of 24 per day, the 3 h values overlapping. The new data will be available as the range (R) of activity in nT and also as a logarithmic index (I) of the range. The exponent relating index to range in nT is based closely on the scale used for computing K values. The new ranges and range indices are available, from June 1987, to users in real time and can be accessed by telephone connection or computer network. Their first year of production is regarded as a trial period during which their value to the scientific and commercial communities will be assessed, together with their potential as indicators of regional and global disturbances' and in which trials will be conducted into ways of eliminating excessive bias at quiet times due to the rate of change of the daily variation field. ?? 1988.

  4. Fractal rigidity in migraine

    NASA Astrophysics Data System (ADS)

    Latka, Miroslaw; Glaubic-Latka, Marta; Latka, Dariusz; West, Bruce J.

    2004-04-01

    We study the middle cerebral artery blood flow velocity (MCAfv) in humans using transcranial Doppler ultrasonography (TCD). Scaling properties of time series of the axial flow velocity averaged over a cardiac beat interval may be characterized by two exponents. The short time scaling exponent (STSE) determines the statistical properties of fluctuations of blood flow velocities in short-time intervals while the Hurst exponent describes the long-term fractal properties. In many migraineurs the value of the STSE is significantly reduced and may approach that of the Hurst exponent. This change in dynamical properties reflects the significant loss of short-term adaptability and the overall hyperexcitability of the underlying cerebral blood flow control system. We call this effect fractal rigidity.

  5. The geomagnetic main field and the geodynamo

    NASA Technical Reports Server (NTRS)

    Bloxham, Jeremy; Roberts, Paul H.

    1991-01-01

    Information available on the geomagnetic main field and the geodynamo is presented. Attention is given to the process of mapping the magnetic field, the last version of International Geomagnetic Reference Field Model, and maps of the magnetic field at the core-mantle boundary and their interpretation. Particular consideration is given to the existing geodynamo theories, with special relation given to the Braginsky and Meytlis theory of core turbulence in which the turbulence differs fundamentally from classical turbulence of Kolmogorov type.

  6. Electric Utility Industry Experience with Geomagnetic Disturbances

    DTIC Science & Technology

    1991-09-01

    the March 13, 1989, geomagnetic storm. Source: North American Electric Reliability Council ................................................ 9 Fig. 2.2...Events and K intensity recorded in North America during the March 13, 1989, geomagnetic storm. Source: North American Electric Reliability Council. 2.2...Unit I experienced VAR excursions of 150 to 200 MVAR. Additional VARs were consumed by the saturated step-up transformers. An empirical equation

  7. The International Geomagnetic Reference Field, 2005

    USGS Publications Warehouse

    Rukstales, Kenneth S.; Love, Jeffrey J.

    2007-01-01

    This is a set of five world charts showing the declination, inclination, horizontal intensity, vertical component, and total intensity of the Earth's magnetic field at mean sea level at the beginning of 2005. The charts are based on the International Geomagnetic Reference Field (IGRF) main model for 2005 and secular change model for 2005-2010. The IGRF is referenced to the World Geodetic System 1984 ellipsoid. Additional information about the USGS geomagnetism program is available at: http://geomag.usgs.gov/

  8. How the geomagnetic field vector reverses polarity

    USGS Publications Warehouse

    Prevot, M.; Mankinen, E.A.; Gromme, C.S.; Coe, R.S.

    1985-01-01

    A highly detailed record of both the direction and intensity of the Earth's magnetic field as it reverses has been obtained from a Miocene volcanic sequence. The transitional field is low in intensity and is typically non-axisymmetric. Geomagnetic impulses corresponding to astonishingly high rates of change of the field sometimes occur, suggesting that liquid velocity within the Earth's core increases during geomagnetic reversals. ?? 1985 Nature Publishing Group.

  9. Geomagnetic main field modeling using magnetohydrodynamic constraints

    NASA Technical Reports Server (NTRS)

    Estes, R. H.

    1985-01-01

    The influence of physical constraints are investigated which may be approximately satisfied by the Earth's liquid core on models of the geomagnetic main field and its secular variation. A previous report describes the methodology used to incorporate nonlinear equations of constraint into the main field model. The application of that methodology to the GSFC 12/83 field model to test the frozen-flux hypothesis and the usefulness of incorporating magnetohydrodynamic constraints for obtaining improved geomagnetic field models is described.

  10. Geomagnetic disturbance effects on power systems

    SciTech Connect

    Albertson, V.D.; Bozoki, B.; Feero, W.E.; Kappenman, J.G.; Larsen, E.V.; Nordell, D.E.; Ponder, J.; Prabhakara, F.S.; Thompson, K.; Walling, R.

    1993-07-01

    In the northern hemisphere, the aurora borealis is visual evidence of simultaneous fluctuations in the earth's magnetic field (geomagnetic field). These geomagnetic disturbances (GMD's), or geomagnetic storms, can affect a number of man-made systems, including electric power systems. The GMD's are caused by the electromagnetic interaction of the solar wind plasma of protons and electrons with the geomagnetic field. These dynamic impulses in the solar wind are due to solar flares, coronal holes, and disappearing filaments, and reach the earth from one to six days after being emitted by a solar event. Instances of geomagnetic storms affecting telegraph systems were noted in England in 1846, and power system disturbances linked to GMD's were first reported in the United States in 1940. This Working Group report is a summary of the state of knowledge and research activity to the present time, and covers the GMD/Geomagnetically-induced currents (GIC) phenomena, transformer effects, the impact on generators, protective relay effects, and communication system effects. It also summarizes modeling and predicting GIC, measuring and monitoring GIC, mitigation methods, system operating guidelines during GMD's, and alerting and forecasting procedures and needs for the power industry.

  11. Electrically conductive rigid polyurethane foam

    DOEpatents

    Neet, T.E.; Spieker, D.A.

    1983-12-08

    A rigid, moldable polyurethane foam comprises about 2 to 10 weight percent, based on the total foam weight, of a carbon black which is CONDUCTEX CC-40-220 or CONDUCTEX SC, whereby the rigid polyurethane foam is electrically conductive and has essentially the same mechanical properties as the same foam without carbon black added.

  12. Electrically conductive rigid polyurethane foam

    DOEpatents

    Neet, Thomas E.; Spieker, David A.

    1985-03-19

    A rigid, polyurethane foam comprises about 2-10 weight percent, based on the total foam weight, of a carbon black which is CONDUCTEX CC-40-220 or CONDUCTEX SC, whereby the rigid polyurethane foam is electrically conductive and has essentially the same mechanical properties as the same foam without carbon black added.

  13. International rigid contact lens prescribing.

    PubMed

    Efron, Nathan; Morgan, Philip B; Helland, Magne; Itoi, Motozumi; Jones, Deborah; Nichols, Jason J; van der Worp, Eef; Woods, Craig A

    2010-06-01

    Rigid lenses have been fitted less since the introduction of soft lenses nearly 40 years ago. Data that we have gathered from annual contact lens fitting surveys conducted in Australia, Canada, Japan, the Netherlands, Norway, the UK and the USA between 2000 and 2008 facilitate an accurate characterization of the pattern of the decline of rigid lens fitting during the first decade of this century. There is a trend for rigid lenses to be utilized primarily for refitting those patients who are already successful rigid lens wearers-most typically older females being refit with higher Dk materials. Rigid lenses are generally fitted on a full-time basis (four or more days of wear per week) without a planned replacement schedule. Orthokeratology is especially popular in the Netherlands, but is seldom prescribed in the other countries surveyed.

  14. On the local Hurst exponent of geomagnetic field fluctuations: Spatial distribution for different geomagnetic activity levels

    NASA Astrophysics Data System (ADS)

    Michelis, Paola De; Consolini, Giuseppe

    2015-04-01

    This study attempts to characterize the spatial distribution of the scaling features of the short time scale magnetic field fluctuations obtained from 45 ground-based geomagnetic observatories distributed in the Northern Hemisphere. We investigate the changes of the scaling properties of the geomagnetic field fluctuations by evaluating the local Hurst exponent and reconstruct maps of this index as a function of the geomagnetic activity level. These maps permit us to localize the different latitudinal structures responsible for disturbances and related to the ionospheric current systems. We find that the geomagnetic field fluctuations associated with the different ionospheric current systems have different scaling features, which can be evidenced by the local Hurst exponent. We also find that in general, the local Hurst exponent for quiet magnetospheric periods is higher than that for more active periods suggesting that the dynamical processes that are activated during disturbed times are responsible for changes in the nature of the geomagnetic field fluctuations.

  15. Ionospheric redistribution during geomagnetic storms.

    PubMed

    Immel, T J; Mannucci, A J

    2013-12-01

    [1]The abundance of plasma in the daytime ionosphere is often seen to grow greatly during geomagnetic storms. Recent reports suggest that the magnitude of the plasma density enhancement depends on the UT of storm onset. This possibility is investigated over a 7year period using global maps of ionospheric total electron content (TEC) produced at the Jet Propulsion Laboratory. The analysis confirms that the American sector exhibits, on average, larger storm time enhancement in ionospheric plasma content, up to 50% in the afternoon middle-latitude region and 30% in the vicinity of the high-latitude auroral cusp, with largest effect in the Southern Hemisphere. We investigate whether this effect is related to the magnitude of the causative magnetic storms. Using the same advanced Dst index employed to sort the TEC maps into quiet and active (Dst<-100 nT) sets, we find variation in storm strength that corresponds closely to the TEC variation but follows it by 3-6h. For this and other reasons detailed in this report, we conclude that the UT-dependent peak in storm time TEC is likely not related to the magnitude of external storm time forcing but more likely attributable to phenomena such as the low magnetic field in the South American region. The large Dst variation suggests a possible system-level effect of the observed variation in ionospheric storm response on the measured strength of the terrestrial ring current, possibly connected through UT-dependent modulation of ion outflow.

  16. On Geomagnetism and Paleomagnetism I

    NASA Technical Reports Server (NTRS)

    Voorhies, Coerte V.

    2000-01-01

    A partial description of Earth's broad scale, core-source magnetic field has been developed and tested three ways. The description features an expected, or mean, spatial magnetic power spectrum that is approximately inversely proportional to horizontal wavenumber atop Earth's core. This multipole spectrum describes a magnetic energy range; it is not steep enough for Gubbins' magnetic dissipation range. Temporal variations of core multipole powers about mean values are to be expected and are described statistically, via trial probability distribution functions, instead of deterministically, via trial solution of closed transport equations. The distributions considered here are closed and neither require nor prohibit magnetic isotropy. The description is therefore applicable to, and tested against, both dipole and low degree non-dipole fields. In Part 1, a physical basis for an expectation spectrum is developed and checked. The description is then combined with main field models of twentieth century satellite and surface geomagnetic field measurements to make testable predictions of the radius of Earth's core. The predicted core radius is 0.7% above the 3480 km seismological value. Partial descriptions of other planetary dipole fields are noted.

  17. Geomagnetically trapped anomalous cosmic rays

    SciTech Connect

    Selesnick, R.S.; Cummings, A.C.; Cummings, J.R.

    1995-06-01

    Since its launch in July 1992, the polar-orbiting satellite SAMPEX has been collecting data on geomagnetically trapped heavy ions, predominantly O, N, and Ne, at energies {ge}15 MeV/nucleon and in a narrow L shell range L = 2. Their location, elemental composition, energy spectra, pitch angle distribution, and time variations all support the theory that these particles originated as singly ionized interplanetary anomalous cosmic rays that were stripped of electrons in the Earth`s upper atmosphere and subsequently trapped. The O are observed primarily at pitch angles outside the atmospheric loss cones, consistent with a trapped population, and their distribution there is nearly isotropic. The abundances relative to O of the N, possible Ne, and especially C are lower than the corresponding interplanetary values, which may be indicative of the trapping efficiencies. The distributions of trapped N, O, and Ne in energy and L shell suggest that most of the ions observed at the SAMPEX altitude of {approximately}600 km are not fully stripped when initially trapped. A comparison of the trapped intensity with the much lower interplanetary intensity of anomalous cosmic rays provides model-dependent estimates of the product of the trapping probability and the average trapped particle lifetime against ionization losses in the residual atmosphere for particles that mirror near the SAMPEX altitude. 36 refs., 13 figs., 1 tab.

  18. Cenozoic Eurasia is not a single rigid plate: Paleomagnetic evidence

    NASA Astrophysics Data System (ADS)

    Cogné, Jean-Pascal

    2013-11-01

    The widely distributed Cenozoic paleomagnetic inclination anomaly in Asia is usually attributed to either a widespread error of magnetic field recording due to an inclination flattening mechanism in sediments, or to the persistence of an anomalous non-dipolar component of the geomagnetic field throughout the Tertiary. Based on an analysis of the Asian paleomagnetic database for Meso-Cenozoic times, we suggest that instead this puzzling anomaly results from an overlooked global plate tectonics cause where the wide so-called Eurasian plate would have suffered from previously undetected transpressive north-south relative movements between its western and eastern ends since the Cretaceous. These relative movements are most probably accommodated by a component of right-lateral shear movement distributed in the Tornquist-Tesseyre zone, and a localized left-lateral shear movement in the Ural Mountain chain during the Tertiary. Therefore, Eurasia was not the single rigid plate that Cenozoic plate reconstructions have accepted.

  19. Bats Use Geomagnetic Field: Behavior and Mechanism

    NASA Astrophysics Data System (ADS)

    Pan, Y.; Tian, L.; Zhang, B.; Zhu, R.

    2015-12-01

    It has been known that numerous animals can use the Earth's magnetic field for spatial orientation and long-distance navigation, nevertheless, how animals can respond to the magnetic field remain mostly ambiguous. The intensities of the global geomagnetic field varies between 23 and 66 μT, and the geomagnetic field intensity could drop to 10% during geomagnetic polarity reversals or geomagnetic excursions. Such dramatic changes of the geomagnetic field may pose a significant challenge for the evolution of magnetic compass in animals. For examples, it is vital whether the magnetic compass can still work in such very weak magnetic fields. Our previous experiment has demonstrated that a migratory bat (Nyctalus plancyi) uses a polarity compass for orientation during roosting when exposed to an artificial magnetic field (100 μT). Recently, we experimentally tested whether the N. plancyi can sense very weak magnetic fields that were even lower than those of the present-day geomagnetic field. Results showed: 1) the bats can sense the magnetic north in a field strength of present-day local geomagnetic field (51μT); 2) As the field intensity decreased to only 1/5th of the natural intensity (10 μT), the bats still responded by positioning themselves at the magnetic north. Notably, as the field polarity was artificially reversed, the bats still preferred the new magnetic north, even at the lowest field strength tested (10 μT). Hence, N. plancyi is able to detect the direction of a magnetic field with intensity range from twice to 1/5th of the present-day field strength. This allows them to orient themselves across the entire range of present-day global geomagnetic field strengths and sense very weak magnetic fields. We propose that this high sensitivity might have evolved in bats as the geomagnetic field strength varied and the polarity reversed tens of times over the past fifty million years since the origin of bats. The physiological mechanisms underlying

  20. The causes of recurrent geomagnetic storms

    NASA Technical Reports Server (NTRS)

    Burlaga, L. F.; Lepping, R. P.

    1976-01-01

    The causes of recurrent geomagnetic activity were studied by analyzing interplanetary magnetic field and plasma data from earth-orbiting spacecraft in the interval from November 1973 to February 1974. This interval included the start of two long sequences of geomagnetic activity and two corresponding corotating interplanetary streams. In general, the geomagnetic activity was related to an electric field which was due to two factors: (1) the ordered, mesoscale pattern of the stream itself, and (2) random, smaller-scale fluctuations in the southward component of the interplanetary magnetic field Bz. The geomagnetic activity in each recurrent sequence consisted of two successive stages. The first stage was usually the most intense, and it occurred during the passage of the interaction region at the front of a stream. These large amplitudes of Bz were primarily produced in the interplanetary medium by compression of ambient fluctuations as the stream steepened in transit to 1 A.U. The second stage of geomagnetic activity immediately following the first was associated with the highest speeds in the stream.

  1. Principles of major geomagnetic storms forecasting

    NASA Astrophysics Data System (ADS)

    Zagnetko, Alexander; Applbaum, David; Dorman, Lev; Pustil'Nik, Lev; Sternlieb, Abraham; Zukerman, Igor

    According to NOAA Space Weather Scales, geomagnetic storms of scales G5 (3-hour index of geomagnetic activity Kp=9), G4 (Kp=8) and G3 (Kp=7) are dangerous for people technology and health (influence on power systems, on spacecraft operations, on HF radio-communications and others). To prevent these serious damages will be very important to forecast dangerous geomagnetic storms. In many papers it was shown that in principle for this forecasting can be used data on CR intensity and CR anisotropy changing before SC of major geomagnetic storms accompanied by sufficient Forbush-decreases (e.g., Dorman et al., 1995, 1999). In this paper we consider all types of observed precursor effects in CR what can be used for forecasting of great geomagnetic storms and possible mechanisms of these precursor effects origin. REFERENCES: Dorman L.I., et al. "Cosmic-ray forecasting features for big Forbush-decreases". Nuclear Physics B, 49A, 136-144 (1995). L.I.Dorman, et al, "Cosmic ray Forbush-decrease as indicators of space dangerous phenomenon and possible use of cosmic ray data for their pre-diction", Proc. of 26-th Intern. Cosmic Ray Conference, Salt Lake City, 6, 476-479 (1999).

  2. Neutral thermosphere modelling using sectorial geomagnetic indices

    NASA Astrophysics Data System (ADS)

    Bezdek, A.; Biancale, R.; Bruinsma, S.; Lathuillere, C.; Menvielle, M.; Valette, J. J.

    Since the 1970 s semi-empirical models of neutral thermospheric density are stuck at a 10--20 precision limit with respect to observations One of the reasons for this is the use of planetary geomagnetic indices i e one value for the whole Earth at a given UT However it is well known that the atmospheric variability related to geomagnetic activity at thermospheric heights is a function while not well known of geographical location cf different physical regimes governing the polar ionosphere In our tests we made use of the so-called a lambda longitude sector geomagnetic index that depends on both the geodetic latitude and longitude the DTM-2000 model of the neutral thermospheric density and the observed densities derived from the accelerometer measurements aboard the CHAMP satellite Using the sectorial index of geomagnetic activity instead of the planetary one improves the agreement of the modelled and observed densities especially during the geomagnetic storms The DTM-2000 algorithm was modified to accommodate these indices which in fact represents the first step of its upcoming complete revision in order to benefit most from the assimilation of the CHAMP and GRACE density data

  3. Coupling Functions for NM-64 and NM Without Lead Derived on the Basis of Calculated Apparent Cutoff Rigidities for CR Latitude Survey from Antarctica to Italy in Minimum of Solar Activity

    NASA Astrophysics Data System (ADS)

    Dorman, L.I.; Danilova, O.A.; Tyasto, M.I.; Ptitsina, N.G.; Villoresi, G.; Iucci, N.; Parisi, M.

    L. I. Dorman (1,2), O. A. Danilova (3), M. I. Tyasto (3), N. G. Ptitsina (3), G. Villoresi (4), N. Iucci (4) and M. Parisi (4) ? (1) Israel Cosmic Ray Center affiliated to Tel Aviv University, Technion and Israel Space Agency, Israel; (2) IZMIRAN, Troitsk, Russia; (3) SPbFIZMIRAN, St. Petersburg, Russia; (4) Dipartimento di Fisica "E. Amaldi", Università "Roma Tre", Rome, Italy In Dorman et al. (2007) it was calculate the apparent cut-off rigidities for the backward route (Antarctica-Italy) of the CR latitude survey performed on a ship during 1996-1997 solar minimum. These computations were done on the basis of results of trajectory calculations for inclined cut-off rigidities for various azimuth and zenith angles (0°, 15°, 30°, 45°, 60°) and azimuth directions changing from 0° to 360° in steps of 45°. The information on integral multiplicities of secondary neutrons detected by neutron monitor in dependence of zenith angle of incoming primary CR particles have been also used. This information is based on the theoretical calculations of meson-nuclear cascades of primary protons with different rigidities arriving to the Earth's atmosphere at zenith angles 0°, 15°, 30°, 45°, 60° and 75°. By using this information and data of CR latitude survey from Antarctica to Italy in minimum of solar activity we determine coupling functions for NM-64 and NM without lead. Reference: L.I. Dorman et al. “Apparent Cutoff Rigidities for Cosmic Ray Latitude Survey from Antarctica to Italy in Minimum of Solar Activity”, Adv. Space Res., 2007 (in press).

  4. Ionospheric redistribution during geomagnetic storms

    PubMed Central

    Immel, T J; Mannucci, A J

    2013-01-01

    [1]The abundance of plasma in the daytime ionosphere is often seen to grow greatly during geomagnetic storms. Recent reports suggest that the magnitude of the plasma density enhancement depends on the UT of storm onset. This possibility is investigated over a 7year period using global maps of ionospheric total electron content (TEC) produced at the Jet Propulsion Laboratory. The analysis confirms that the American sector exhibits, on average, larger storm time enhancement in ionospheric plasma content, up to 50% in the afternoon middle-latitude region and 30% in the vicinity of the high-latitude auroral cusp, with largest effect in the Southern Hemisphere. We investigate whether this effect is related to the magnitude of the causative magnetic storms. Using the same advanced Dst index employed to sort the TEC maps into quiet and active (Dst<−100 nT) sets, we find variation in storm strength that corresponds closely to the TEC variation but follows it by 3–6h. For this and other reasons detailed in this report, we conclude that the UT-dependent peak in storm time TEC is likely not related to the magnitude of external storm time forcing but more likely attributable to phenomena such as the low magnetic field in the South American region. The large Dst variation suggests a possible system-level effect of the observed variation in ionospheric storm response on the measured strength of the terrestrial ring current, possibly connected through UT-dependent modulation of ion outflow. PMID:26167429

  5. Stratospheric Balloon Gradient Geomagnetic Measurements

    NASA Astrophysics Data System (ADS)

    Filippov, Sergey; Tsvetkov, Yury

    The study of the interior structure of the Earth and laws of its evolution is one of the most difficult problems of natural science. Among the geophysical fields the anomaly magnetic field is one of the most informational in questions of the Earth's crust structure. Many important parameters of an environment are expedient for measuring at lower altitudes, than satellite ones. So, one of the alternatives is stratospheric balloon survey. The balloon flight altitudes cover the range from 20 to 50 km. At such altitudes there are steady zone air flows due to which the balloon flight trajectories can be of any direction, including round-the-world (round-the-pole). One of the examples of such sounding system have been designed, developed and maintained at IZMIRAN during already about 20 years. This system consists of three instrumental con-tainers uniformly placed along a vertical 6 km line. System allows measuring a module and vertical gradient of the geomagnetic field along the whole flight trajectory and so one's name is -stratospheric balloon magnetic gradiometer (SMBG). The GPS-receivers, located in each instrumental container, fix the flight coordinates to within several tens meters. Data trans-mission is carried out by Globalstar satellite link. The obtained data are used in solving the problems of deep sounding of the Earth's crust magnetic structure -an extraction of magnetic anomalies, determination of a depth of bedding of magnetoactive rocks and others. The developed launching technology, deployment in flight, assembly, data processing, transfer and landing the containers with the equipment can be used for other similar problems of monitoring and sounding an environment. Useful flight weights of each instrumental container may be reaching 50 kg. More than ten testing flights (1986-2009) at stratospheric altitudes (20-30 km) have proven the reliability of this system.

  6. Cosmic ray decreases and geomagnetic activity: list of events 1982-2002

    NASA Astrophysics Data System (ADS)

    Kudela, K.; Brenkus, R.

    2004-09-01

    Decreases in cosmic ray (CR) intensity provided by neutron monitors, for the time period 1982-2002, are summarized and compared with simultaneous changes in Dst index. Data from four neutron monitors with different vertical cutoff rigidities are used, namely Oulu (~0.8GV), Lomnický Štít (~4GV) and Haleakala/Huancayo (~13GV). The Dst behaviour during different periods of CR decreases is rather complex. Along with the events when CR decreases are accompanied by corresponding Dst depressions, there are several effects when geomagnetic activity (measured by Dst) is not changing significantly. In some cases large Dst depression is not marked by CR decreases. This work presents 2 tables of CR events as a function of geomagnetic activity. The tables, indicating 19% of CR decreases without Dst variability and 28% of Dst variabilities without clear CR decreases, may be useful for investigating the relation between CR flux values and atmospheric effects and for eventual discrimination between CR flux and geomagnetic activity level influence on the atmospheric processes.

  7. Magnetospheric mapping with quantitative geomagnetic field models

    NASA Technical Reports Server (NTRS)

    Fairfield, D. H.; Mead, G. D.

    1973-01-01

    The Mead-Fairfield geomagnetic field models were used to trace field lines between the outer magnetosphere and the earth's surface. The results are presented in terms of ground latitude and local time contours projected to the equatorial plane and into the geomagnetic tail. With these contours various observations can be mapped along field lines between high and low altitudes. Low altitudes observations of the polar cap boundary, the polar cusp, the energetic electron trapping boundary and the sunward convection region are projected to the equatorial plane and compared with the results of the model and with each other. The results provide quantitative support to the earlier suggestions that the trapping boundary is associated with the last closed field line in the sunward hemisphere, the polar cusp is associated with the region of the last closed field line, and the polar cap projects to the geomagnetic tail and has a low latitude boundary corresponding to the last closed field line.

  8. Quantifying Power Grid Risk from Geomagnetic Storms

    NASA Astrophysics Data System (ADS)

    Homeier, N.; Wei, L. H.; Gannon, J. L.

    2012-12-01

    We are creating a statistical model of the geophysical environment that can be used to quantify the geomagnetic storm hazard to power grid infrastructure. Our model is developed using a database of surface electric fields for the continental United States during a set of historical geomagnetic storms. These electric fields are derived from the SUPERMAG compilation of worldwide magnetometer data and surface impedances from the United States Geological Survey. This electric field data can be combined with a power grid model to determine GICs per node and reactive MVARs at each minute during a storm. Using publicly available substation locations, we derive relative risk maps by location by combining magnetic latitude and ground conductivity. We also estimate the surface electric fields during the August 1972 geomagnetic storm that caused a telephone cable outage across the middle of the United States. This event produced the largest surface electric fields in the continental U.S. in at least the past 40 years.

  9. Scaling laws from geomagnetic time series

    USGS Publications Warehouse

    Voros, Z.; Kovacs, P.; Juhasz, A.; Kormendi, A.; Green, A.W.

    1998-01-01

    The notion of extended self-similarity (ESS) is applied here for the X - component time series of geomagnetic field fluctuations. Plotting nth order structure functions against the fourth order structure function we show that low-frequency geomagnetic fluctuations up to the order n = 10 follow the same scaling laws as MHD fluctuations in solar wind, however, for higher frequencies (f > l/5[h]) a clear departure from the expected universality is observed for n > 6. ESS does not allow to make an unambiguous statement about the non triviality of scaling laws in "geomagnetic" turbulence. However, we suggest to use higher order moments as promising diagnostic tools for mapping the contributions of various remote magnetospheric sources to local observatory data. Copyright 1998 by the American Geophysical Union.

  10. An introduction to quiet daily geomagnetic fields

    USGS Publications Warehouse

    Campbell, W.H.

    1989-01-01

    On days that are quiet with respect to solar-terrestrial activity phenomena, the geomagnetic field has variations, tens of gamma in size, with major spectral components at about 24, 12, 8, and 6 hr in period. These quiet daily field variations are primarily due to the dynamo currents flowing in the E region of the earth's ionosphere, are driven by the global thermotidal wind systems, and are dependent upon the local tensor conductivity and main geomagnetic field vector. The highlights of the behavior and interpretation of these quiet field changes, from their discovery in 1634 until the present, are discussed as an introduction to the special journal issue on Quiet Daily Geomagnetic Fields. ?? 1989 Birkha??user Verlag.

  11. International Geomagnetic Reference Field: the third generation.

    USGS Publications Warehouse

    Peddie, N.W.

    1982-01-01

    In August 1981 the International Association of Geomagnetism and Aeronomy revised the International Geomagnetic Reference Field (IGRF). It is the second revision since the inception of the IGRF in 1968. The revision extends the earlier series of IGRF models from 1980 to 1985, introduces a new series of definitive models for 1965-1976, and defines a provisional reference field for 1975- 1980. The revision consists of: 1) a model of the main geomagnetic field at 1980.0, not continuous with the earlier series of IGRF models together with a forecast model of the secular variation of the main field during 1980-1985; 2) definitive models of the main field at 1965.0, 1970.0, and 1975.0, with linear interpolation of the model coefficients specified for intervening dates; and 3) a provisional reference field for 1975-1980, defined as the linear interpolation of the 1975 and 1980 main-field models.-from Author

  12. The causes of geomagnetic storms during solar maximum

    NASA Technical Reports Server (NTRS)

    Tsurutani, Bruce T.; Gonzalez, Walter D.

    1994-01-01

    One of the oldest mysteries in geomagnetism is the linkage between solar and geomagnetic activity. In investigating the causes of geomagnetic storms occurring during solar maximum, the following topics are discussed: solar phenomena; types of solar wind; magnetic reconnection and magnetic storms; an interplanetary example; and future space physics missions.

  13. Tsunami related to solar and geomagnetic activity

    NASA Astrophysics Data System (ADS)

    Cataldi, Gabriele; Cataldi, Daniele; Straser, Valentino

    2016-04-01

    The authors of this study wanted to verify the existence of a correlation between earthquakes of high intensity capable of generating tsunami and variations of solar and Earth's geomagnetic activity. To confirming or not the presence of this kind of correlation, the authors analyzed the conditions of Spaceweather "near Earth" and the characteristics of the Earth's geomagnetic field in the hours that preceded the four earthquakes of high intensity that have generated tsunamis: 1) Japan M9 earthquake occurred on March 11, 2011 at 05:46 UTC; 2) Japan M7.1 earthquake occurred on October 25, 2013 at 17:10 UTC; 3) Chile M8.2 earthquake occurred on April 1, 2014 at 23:46 UTC; 4) Chile M8.3 earthquake occurred on September 16, 2015 at 22:54 UTC. The data relating to the four earthquakes were provided by the United States Geological Survey (USGS). The data on ion density used to realize the correlation study are represented by: solar wind ion density variation detected by ACE (Advanced Composition Explorer) Satellite, in orbit near the L1 Lagrange point, at 1.5 million of km from Earth, in direction of the Sun. The instrument used to perform the measurement of the solar wind ion density is the Electron, Proton, and Alpha Monitor (EPAM) instrument, equipped on the ACE Satellite. To conduct the study, the authors have taken in consideration the variation of the solar wind protons density of three different energy fractions: differential proton flux 1060-1900 keV (p/cm^2-sec-ster-MeV); differential proton flux 761-1220 keV (p/cm^2-sec-ster-MeV); differential proton flux 310-580 keV (p/cm^2-sec-ster-MeV). Geomagnetic activity data were provided by Tromsø Geomagnetic Observatory (TGO), Norway; by Scoresbysund Geomagnetic Observatory (SCO), Greenland, Denmark and by Space Weather Prediction Center of Pushkov Institute of terrestrial magnetism, ionosphere and radio wave propagation (IZMIRAN), Troitsk, Moscow Region. The results of the study, in agreement with what already

  14. Large Geomagnetic Storms: Introduction to Special Section

    NASA Technical Reports Server (NTRS)

    Gopalswamy, N.

    2010-01-01

    Solar cycle 23 witnessed the accumulation of rich data sets that reveal various aspects of geomagnetic storms in unprecedented detail both at the Sun where the storm causing disturbances originate and in geospace where the effects of the storms are directly felt. During two recent coordinated data analysis workshops (CDAWs) the large geomagnetic storms (Dst < or = -100 nT) of solar cycle 23 were studied in order to understand their solar, interplanetary, and geospace connections. This special section grew out of these CDAWs with additional contributions relevant to these storms. Here I provide a brief summary of the results presented in the special section.

  15. Satellite Data for Geomagnetic Field Modeling

    NASA Technical Reports Server (NTRS)

    Langel, R. A.; Baldwin, R. T.

    1992-01-01

    Satellite measurements of the geomagnetic fields began with the launch of Sputnik 3 in May of 1958 and have continued sporadically. Spacecraft making significant contributions to main field geomagnetism will be reviewed and the characteristics of their data discussed, including coverage, accuracy, resolution and data availability. Of particular interest are Vanguard 3; Cosmos 49, Ogo's -2, -4, and -6; Magsat; DE-2; and POGS. Spacecraft make measurements on a moving platfrom above the ionosphere as opposed to measurements from fixed observatories and surveys, both below the ionosphere. Possible future missions, such as Aristoteles and GOS are reviewed.

  16. Satellite data for geomagnetic field modeling

    NASA Astrophysics Data System (ADS)

    Langel, R. A.; Baldwin, R. T.

    1992-06-01

    Satellite measurements of the geomagnetic fields began with the launch of Sputnik 3 in May of 1958 and have continued sporadically. Spacecraft making significant contributions to main field geomagnetism will be reviewed and the characteristics of their data discussed, including coverage, accuracy, resolution and data availability. Of particular interest are Vanguard 3; Cosmos 49, Ogo's -2, -4, and -6; Magsat; DE-2; and POGS. Spacecraft make measurements on a moving platfrom above the ionosphere as opposed to measurements from fixed observatories and surveys, both below the ionosphere. Possible future missions, such as Aristoteles and GOS are reviewed.

  17. Anencephalus, drinking water, geomagnetism and cosmic radiation.

    PubMed

    Archer, V E

    1979-01-01

    The mortality rates from anencephalus from 1950-1969 in Canadian cities are shown to be strongly correlated with city growth rate and with horizontal geomagnetic flux, which is directly related to the intensity of cosmic radiation. They are also shown to have some association with the magnesium content of drinking water. Prior work with these data which showed associations with magnesium in drinking water, mean income, latitude and longitude was found to be inadequate because it dismissed the observed geographic associations as having little biological meaning, and because the important variables of geomagnetism and city growth rate were overlooked.

  18. Atmospheric Entry Studies for Venus Missions: 45 Sphere-Cone Rigid Aeroshells and Ballistic Entries

    NASA Technical Reports Server (NTRS)

    Prabhu, Dinesh K.; Spilker, Thomas R.; Allen, Gary A., Jr.; Hwang, Helen H.; Cappuccio, Gelsomina; Moses, Robert W.

    2013-01-01

    The present study considers direct ballistic entries into the atmosphere of Venus using a 45deg sphere-cone rigid aeroshell, a legacy shape that has been used successfully in the past in the Pioneer Venus Multiprobe Mission. For a number of entry mass and heatshield diameter combinations (i.e., various ballistic coefficients) and entry velocities, the trajectory space in terms of entry flight path angles between skip out and -30deg is explored with a 3DoF trajectory code, TRAJ. From these trajectories, the viable entry flight path angle space is determined through the use of mechanical and thermal performance limits on the thermal protection material and science payload; the thermal protection material of choice is entry-grade carbon phenolic, for which a material thermal response model is available. For mechanical performance, a 200 g limit is placed on the peak deceleration load experienced by the science instruments, and 10 bar is assumed as the pressure limit for entry-grade carbon-phenolic material. For thermal performance, inflection points in the total heat load distribution are used as cut off criteria. Analysis of the results shows the existence of a range of critical ballistic coefficients beyond which the steepest possible entries are determined by the pressure limit of the material rather than the deceleration load limit.

  19. Attitude dynamics and control of spacecraft using geomagnetic Lorentz force

    NASA Astrophysics Data System (ADS)

    Abdel-Aziz, Yehia A.; Shoaib, Muhammad

    2015-01-01

    Attitude stabilization of a charged rigid spacecraft in Low Earth Orbit using torques due to Lorentz force in pitch and roll directions is considered. A spacecraft that generates an electrostatic charge on its surface in the Earth's magnetic field will be subject to perturbations from the Lorentz force. The Lorentz force acting on an electrostatically charged spacecraft may provide a useful thrust for controlling a spacecraft's orientation. We assume that the spacecraft is moving in the Earth's magnetic field in an elliptical orbit under the effects of gravitational, geomagnetic and Lorentz torques. The magnetic field of the Earth is modeled as a non-tilted dipole. A model incorporating all Lorentz torques as a function of orbital elements has been developed on the basis of electric and magnetic fields. The stability of the spacecraft orientation is investigated both analytically and numerically. The existence and stability of equilibrium positions is investigated for different values of the charge to mass ratio (α*). Stable orbits are identified for various values of α*. The main parameters for stabilization of the spacecraft are α* and the difference between the components of the moment of inertia for the spacecraft.

  20. Planetary distribution of geomagnetic pulsations during a geomagnetic storm at solar minimum

    NASA Astrophysics Data System (ADS)

    Kleimenova, N. G.; Kozyreva, O. V.

    2014-01-01

    We investigate the features of the planetary distribution of wave phenomena (geomagnetic pulsations) in the Earth's magnetic shell (the magnetosphere) during a strong geomagnetic storm on December 14-15, 2006, which is untypical of the minimum phase of solar activity. The storm was caused by the approach of the interplanetary magnetic cloud towards the Earth's magnetosphere. The study is based on the analysis of 1-min data of global digital geomagnetic observations at a few latitudinal profiles of the global network of ground-based magnetic stations. The analysis is focused on the Pc5 geomagnetic pulsations, whose frequencies fall in the band of 1.5-7 mHz ( T ˜ 2-10 min), on the fluctuations in the interplanetary magnetic field (IMF) and in the solar wind density in this frequency band. It is shown that during the initial phase of the storm with positive IMF Bz, most intense geomagnetic pulsations were recorded in the dayside polar regions. It was supposed that these pulsations could probably be caused by the injection of the fluctuating streams of solar wind into the Earth's ionosphere in the dayside polar cusp region. The fluctuations arising in the ionospheric electric currents due to this process are recorded as the geomagnetic pulsations by the ground-based magnetometers. Under negative IMF Bz, substorms develop in the nightside magnetosphere, and the enhancement of geomagnetic pulsations was observed in this latitudinal region on the Earth's surface. The generation of these pulsations is probably caused by the fluctuations in the field-aligned magnetospheric electric currents flowing along the geomagnetic field lines from the substorm source region. These geomagnetic pulsations are not related to the fluctuations in the interplanetary medium. During the main phase of the magnetic storm, when fluctuations in the interplanetary medium are almost absent, the most intense geomagnetic pulsations were observed in the dawn sector in the region corresponding to the

  1. Determining the Optimum Cut-Off Grades in Sulfide Copper Deposits / Określanie Optymalnej Wartości Odcięcia Zawartości Procentowej Pierwiastka Użytecznego W Złożach Siarczku Miedzi

    NASA Astrophysics Data System (ADS)

    Rahimi, Esmaeil; Oraee, Kazem; Shafahi, Zia Aldin; Ghasemzadeh, Hasan

    2015-03-01

    Optimum cut-off grades determination in mining life affects production planning and ultimate pit limit and it is also important from social, economical and environmental aspects. Calculation of optimum cut-off grades has been less considered for mines containing various mineral processing methods. In this paper, an optimization technique is applied to obtain optimum cut-off grades for both concentration and heap leaching processes. In this technique, production costs and different recoveries of heap leaching method directed into modeling different annual cash flows in copper mines. Considering the governing constraints, the Lagrange multiplier method is practiced to optimize the cut-off grades in which the objective function is supposed to maximize Net Present Value. The results indicate the effect of heap leaching process on the optimum cut-off grades of primary and secondary sulfide deposits. Określanie optymalnego poziomu odcięcia dla zawartości procentowej pierwiastka użytecznego ma poważny wpływ na planowanie produkcji, określanie ostatecznych limitów zasobów złoża; jest to także ważna kwestia z punktu widzenia kwestii społecznych, ekonomicznych i środowiskowych. Obliczanie optymalnego poziomu odcięcia dla zawartości procentowej pierwiastka użytecznego nie było zwykle szeroko rozważane w przypadku kopalni prowadzących ciągły system przeróbki. W pracy tej przedstawiono technikę optymalizacji określania poziomu zawartości procentowej pierwiastka użytecznego z uwzględnieniem zarówno procesów koncentracji jak i ługowania. W metodzie uwzględniono koszty produkcji i różne wskaźniki odzysku rudy, wielkości te wykorzystane zostały do modelowania rocznych przepływów gotówki w kopalniach miedzi. Uwzględniając narzucone ograniczenia, zastosowano metodę mnożników Lagrange'a w celu optymalizacji określania poziomu zawartości procentowej pierwiastka użytecznego, gdzie przyjętą funkcją celu jest

  2. Space radiation enhancement linked to geomagnetic disturbances.

    PubMed

    Tomita, F; Den, M; Doke, T; Hayashi, T; Nagaoka, T; Kato, M

    1998-01-01

    Space radiation dosimetry measurements have been made on board the Space Shuttle. A newly developed active detector called "Real-time Radiation Monitoring Device (RRMD)" was used (Doke et al., 1995; Hayashi et al., 1995). The RRMD results indicate that low Linear Energy Transfer (LET) particles steadily penetrate around the South Atlantic Anomaly (SAA) without clear enhancement of dose equivalent and some daily periodic enhancements of dose equivalent due to high LET particles are seen at the lower geomagnetic cutoff regions (Doke et al., 1996). We also have been analyzing the space weather during the experiment, and found that the anomalous high-energy particle enhancement was linked to geomagnetic disturbance due to the high speed solar wind from a coronal hole. Additional analysis and other experiments are necessary for clarification of these phenomena. If a penetration of high-energy particles into the low altitude occurs by common geomagnetic disturbances, the prediction of geomagnetic activity becomes more important in the next Space Station's era.

  3. On the causes of geomagnetic activity

    NASA Technical Reports Server (NTRS)

    Svalgaard, L.

    1975-01-01

    The causes of geomagnetic activity are studied both theoretically in terms of the reconnection model and empirically using the am-index and interplanetary solar wind parameters. It is found that two separate mechanisms supply energy to the magnetosphere. One mechanism depends critically on the magnitude and direction of the interplanetary magnetic field. Both depend strongly on solar wind speed.

  4. Geomagnetic referencing in the arctic environment

    USGS Publications Warehouse

    Podjono, Benny; Beck, Nathan; Buchanan, Andrew; Brink, Jason; Longo, Joseph; Finn, Carol A.; Worthington, E. William

    2011-01-01

    Geomagnetic referencing is becoming an increasingly attractive alternative to north-seeking gyroscopic surveys to achieve the precise wellbore positioning essential for success in today's complex drilling programs. However, the greater magnitude of variations in the geomagnetic environment at higher latitudes makes the application of geomagnetic referencing in those areas more challenging. Precise, real-time data on those variations from relatively nearby magnetic observatories can be crucial to achieving the required accuracy, but constructing and operating an observatory in these often harsh environments poses a number of significant challenges. Operational since March 2010, the Deadhorse Magnetic Observatory (DED), located in Deadhorse, Alaska, was created through collaboration between the United States Geological Survey (USGS) and a leading oilfield services supply company. DED was designed to produce real-time geomagnetic data at the required level of accuracy, and to do so reliably under the extreme temperatures and harsh weather conditions often experienced in the area. The observatory will serve a number of key scientific communities as well as the oilfield drilling industry, and has already played a vital role in the success of several commercial ventures in the area, providing essential, accurate data while offering significant cost and time savings, compared with traditional surveying techniques.

  5. Geomagnetic referencing in the arctic environment

    USGS Publications Warehouse

    Poedjono, B.; Beck, N.; Buchanan, A. C.; Brink, J.; Longo, J.; Finn, C.A.; Worthington, E.W.

    2011-01-01

    Geomagnetic referencing is becoming an increasingly attractive alternative to north-seeking gyroscopic surveys to achieve the precise wellbore positioning essential for success in today's complex drilling programs. However, the greater magnitude of variations in the geomagnetic environment at higher latitudes makes the application of geomagnetic referencing in those areas more challenging. Precise, real-time data on those variations from relatively nearby magnetic observatories can be crucial to achieving the required accuracy, but constructing and operating an observatory in these often harsh environments poses a number of significant challenges. Operational since March 2010, the Deadhorse Magnetic Observatory (DED), located in Deadhorse, Alaska, was created through collaboration between the United States Geological Survey (USGS) and a leading oilfield services supply company. DED was designed to produce real-time geomagnetic data at the required level of accuracy, and to do so reliably under the extreme temperatures and harsh weather conditions often experienced in the area. The observatory will serve a number of key scientific communities as well as the oilfield drilling industry, and has already played a vital role in the success of several commercial ventures in the area, providing essential, accurate data while offering significant cost and time savings, compared with traditional surveying techniques. Copyright 2011, Society of Petroleum Engineers.

  6. Geomagnetic storms: historical perspective to modern view

    NASA Astrophysics Data System (ADS)

    Lakhina, Gurbax S.; Tsurutani, Bruce T.

    2016-12-01

    The history of geomagnetism is more than 400 years old. Geomagnetic storms as we know them were discovered about 210 years ago. There has been keen interest in understanding Sun-Earth connection events, such as solar flares, CMEs, and concomitant magnetic storms in recent times. Magnetic storms are the most important component of space weather effects on Earth. We give an overview of the historical aspects of geomagnetic storms and the progress made during the past two centuries. Super magnetic storms can cause life-threatening power outages and satellite damage, communication failures and navigational problems. The data for such super magnetic storms that occurred in the last 50 years during the space era is sparce. Research on historical geomagnetic storms can help to create a database for intense and super magnetic storms. New knowledge of interplanetary and solar causes of magnetic storms gained from spaceage observations will be used to review the super magnetic storm of September 1-2, 1859. We discuss the occurrence probability of such super magnetic storms, and the maximum possible intensity for the effects of a perfect ICME: extreme super magnetic storm, extreme magnetospheric compression, and extreme magnetospheric electric fields.

  7. Incorporation of geomagnetic data and services into EPOS infrastructure

    NASA Astrophysics Data System (ADS)

    Hejda, Pavel; Chambodut, Aude; Curto, Juan-Jose; Flower, Simon; Kozlovskaya, Elena; Kubašta, Petr; Matzka, Jürgen; Tanskanen, Eija; Thomson, Alan

    2016-04-01

    Monitoring of the geomagnetic field has a long history across Europe that dates back to 1830', and is currently experiencing an increased interest within Earth observation and space weather monitoring. Our goals within EPOS-IP are to consolidate the community, modernise data archival and distribution formats for existing services and create new services for magnetotelluric data and geomagnetic models. Specific objectives are: • Enhance existing services providing geomagnetic data (INTERMAGNET- INTErnational Real-time MAGnetic observatory NETwork; World Data Centre for Geomagnetism; IMAGE- International Monitor for Auroral Geomagnetic Effects) and existing services providing geomagnetic indices (ISGI - International Service of Geomagnetic Indices). • Develop and enhance the geomagnetic community's metadata systems by creating a metadata database, filling it and putting in place processes to ensure that it is kept up to date in the future. • Develop and build access to magnetotelluric (MT) data including transfer functions and time series data from temporary, portable MT-arrays in Europe, as well as to lithospheric conductivity models derived from TM-data. • Develop common web and database access points to global and regional geomagnetic field and conductivity models. • Establish links from the geomagnetic data services, products and models to the Integrated Core Services. The immediate task in the current period is to identify data models of existing services, modify them and integrate into a common model of Geomagnetic Thematic Core Services.

  8. What do we mean by accuracy in geomagnetic measurements?

    USGS Publications Warehouse

    Green, A.W.

    1990-01-01

    High accuracy is what distinguishes measurements made at the world's magnetic observatories from other types of geomagnetic measurements. High accuracy in determining the absolute values of the components of the Earth's magnetic field is essential to studying geomagnetic secular variation and processes at the core mantle boundary, as well as some magnetospheric processes. In some applications of geomagnetic data, precision (or resolution) of measurements may also be important. In addition to accuracy and resolution in the amplitude domain, it is necessary to consider these same quantities in the frequency and space domains. New developments in geomagnetic instruments and communications make real-time, high accuracy, global geomagnetic observatory data sets a real possibility. There is a growing realization in the scientific community of the unique relevance of geomagnetic observatory data to the principal contemporary problems in solid Earth and space physics. Together, these factors provide the promise of a 'renaissance' of the world's geomagnetic observatory system. ?? 1990.

  9. Specifying spacecraft flexible appendage rigidity

    NASA Technical Reports Server (NTRS)

    Seltzer, S. M.; Shelton, H. L.

    1977-01-01

    As a method for specifying the required degree of rigidity of spacecraft flexible appendages, an analytical technique is proposed for establishing values for the frequency, damping ratio, and modal gain (deflection) of the first several bending modes. The shortcomings of the technique result from the limitations associated with the order of the equations that can be handled practically. An iterative method is prescribed for handling a system whose structural flexibility is described by more than one normal mode. The analytical technique is applied to specifying solar panel rigidity constraints for the NASA Space Telescope. The traditional nonanalytic procedure for specifying the required degree of rigidity of spacecraft flexible appendages has been to set a lower limit below which bending mode frequencies may not lie.

  10. Rigidly foldable origami gadgets and tessellations.

    PubMed

    Evans, Thomas A; Lang, Robert J; Magleby, Spencer P; Howell, Larry L

    2015-09-01

    Rigidly foldable origami allows for motion where all deflection occurs at the crease lines and facilitates the application of origami in materials other than paper. In this paper, we use a recently discovered method for determining rigid foldability to identify existing flat-foldable rigidly foldable tessellations, which are also categorized. We introduce rigidly foldable origami gadgets which may be used to modify existing tessellations or to create new tessellations. Several modified and new rigidly foldable tessellations are presented.

  11. Rigidly foldable origami gadgets and tessellations

    PubMed Central

    Evans, Thomas A.; Lang, Robert J.; Magleby, Spencer P.; Howell, Larry L.

    2015-01-01

    Rigidly foldable origami allows for motion where all deflection occurs at the crease lines and facilitates the application of origami in materials other than paper. In this paper, we use a recently discovered method for determining rigid foldability to identify existing flat-foldable rigidly foldable tessellations, which are also categorized. We introduce rigidly foldable origami gadgets which may be used to modify existing tessellations or to create new tessellations. Several modified and new rigidly foldable tessellations are presented. PMID:26473037

  12. A Study on local geomagnetic activity trend and singularity with geomagnetic data at Cheongyang Magnetic Observatory, Korea

    NASA Astrophysics Data System (ADS)

    Lee, Y.; Jeon, Y.; Ryoo, S.

    2011-12-01

    The KMA(Korea Meteorological Administration) has installed and operated the geomagnetic observatory at Cheongyang-gun, Chungcheongnam-do, Korea which started in April, 2009. As Cheongyang geomagnetic observatory, it has been automatically observing total-, X-, Y- and Z-component data at 1-sec interval and storing in real-time. The National Institute of Meteorological Research, which belongs to KMA, proceeded with their work on the production of K-index that is used for geomagnetic activity observation. In addition, we detect the starting and ending of geomagnetic storm as typical thing of global geomagnetic field change and utilize it for showing current status of geomagnetic storm occurrence. It has been reported that geomagnetic storm occurred seven times during from April, 2010 to July, 2011. It was 5 of the maximum K-index value during geomagnetic storm occurrence period and thought mostly to have been caused by coronal hole and CME(Coronal Mass Ejection). Yet the geomagnetic storm has not been had much of an impact locally. At Cheongyang Observatory, a significantly disturbed geomagnetic data was seen as related to the Tohoku, Japan Earthquake, Mw 9.0, on March 11, 2011. Compared to seismic wave data at Seosan seismic observatory 60km away from Cheongyang geomagnetic observatory, we identified the signal involved to the Tohoku, Japan Earthquake. The power spectral density of the disturbed signal has the dominant frequency band of about 0.05 to 0.1 Hz. We should proceed additional study about this in detail.

  13. Rigidity-tuning conductive elastomer

    NASA Astrophysics Data System (ADS)

    Shan, Wanliang; Diller, Stuart; Tutcuoglu, Abbas; Majidi, Carmel

    2015-06-01

    We introduce a conductive propylene-based elastomer (cPBE) that rapidly and reversibly changes its mechanical rigidity when powered with electrical current. The elastomer is rigid in its natural state, with an elastic (Young’s) modulus of 175.5 MPa, and softens when electrically activated. By embedding the cPBE in an electrically insulating sheet of polydimethylsiloxane (PDMS), we create a cPBE-PDMS composite that can reversibly change its tensile modulus between 37 and 1.5 MPa. The rigidity change takes ˜6 s and is initiated when a 100 V voltage drop is applied across the two ends of the cPBE film. This magnitude of change in elastic rigidity is similar to that observed in natural skeletal muscle and catch connective tissue. We characterize the tunable load-bearing capability of the cPBE-PDMS composite with a motorized tensile test and deadweight experiment. Lastly, we demonstrate the ability to control the routing of internal forces by embedding several cPBE-PDMS ‘active tendons’ into a soft robotic pneumatic bending actuator. Selectively activating the artificial tendons controls the neutral axis and direction of bending during inflation.

  14. Rigid gas permeable extended wear.

    PubMed

    Maehara, J R; Kastl, P R

    1994-04-01

    We have reviewed the pertinent literature on rigid gas permeable (RGP) extended wear contact lenses, and we discuss the benefits and adverse reactions of this contact lens modality, drawing conclusions from reviewed studies. We suggest parameters for success with these lenses and guidelines for the prevention of adverse reactions.

  15. [Can solar/geomagnetic activity restrict the occurrence of some shellfish poisoning outbreaks? The example of PSP caused by Gymnodinium catenatum at the Atlantic Portuguese coast].

    PubMed

    Vale, P

    2013-01-01

    Cyclic outbreaks of accumulation of paralytic shellfish poisoning (PSP) toxins in mussels attributed to Gymnodinium catenatum blooms displayed several of the highest inter-annual maxima coincidental with minima of the 11-year solar sunspot number (SSN) cycle. The monthly distribution of PSP was associated with low levels of the solar radio flux, a more quantitative approach than SSN for fluctuations in solar activity. A comparison between monthly distribution of PSP and other common biotoxins (okadaic acid (OA), dinophysistoxin-2 (DTX2) and amnesic shellfish poisoning (ASP) toxins) demonstrated that only PSP was significantly associated with low levels of radio flux (p < 0.01). PSP occurrence suggests a prior decline in solar activity could be required to act as a trigger, in a similar manner to a photoperiodic signal. The seasonal frequency increased towards autumn during the study period, which might be related to the progressive atmospheric cut-off of deleterious radiation associated with the seasonal change in solar declination, and might play an additional role in seasonal signal-triggering. PSP distribution was also associated with low levels of the geomagnetic index Aa. A comparison between monthly distribution of PSP and other common biotoxins, also demonstrated that only PSP was significantly associated with low levels of the Aa index (p < 0.01). In some years of SSN minima no significant PSP-outbreaks in mussels were detected. This was attributed to a steady rise in geomagnetic activity that could disrupt the triggering signal. Global distribution patterns show that hotspots for G. catenatum blooms are regions with deficient crustal magnetic anomalies. In addition to the variable magnetic field mostly of solar origin, static fields related to magnetized rocks in the crust and upper mantle might play a role in restricting worldwide geographic distribution.

  16. Steady induction effects in geomagnetism. Part 1A: Steady motional induction of geomagnetic chaos

    NASA Technical Reports Server (NTRS)

    Voorhies, Coerte V.

    1992-01-01

    Geomagnetic effects of magnetic induction by hypothetically steady fluid motion and steady magnetic flux diffusion near the top of Earth's core are investigated using electromagnetic theory, simple magnetic earth models, and numerical experiments with geomagnetic field models. The problem of estimating a steady fluid velocity field near the top of Earth's core which induces the secular variation indicated by broad-scale models of the observed geomagnetic field is examined and solved. In Part 1, the steady surficial core flow estimation problem is solved in the context of the source-free mantle/frozen-flux core model. In the first paper (IA), the theory underlying such estimates is reviewed and some consequences of various kinematic and dynamic flow hypotheses are derived. For a frozen-flux core, fluid downwelling is required to change the mean square normal magnetic flux density averaged over the core-mantle boundary. For surficially geostrophic flow, downwelling implies poleward flow. The solution of the forward steady motional induction problem at the surface of a frozen-flux core is derived and found to be a fine, easily visualized example of deterministic chaos. Geomagnetic effects of statistically steady core surface flow may well dominate secular variation over several decades. Indeed, effects of persistent, if not steady, surficially geostrophic core flow are described which may help explain certain features of the present broad-scale geomagnetic field and perhaps paleomagnetic secular variation.

  17. Geomagnetic modeling by optimal recursive filtering

    NASA Technical Reports Server (NTRS)

    Gibbs, B. P.; Estes, R. H.

    1981-01-01

    The results of a preliminary study to determine the feasibility of using Kalman filter techniques for geomagnetic field modeling are given. Specifically, five separate field models were computed using observatory annual means, satellite, survey and airborne data for the years 1950 to 1976. Each of the individual field models used approximately five years of data. These five models were combined using a recursive information filter (a Kalman filter written in terms of information matrices rather than covariance matrices.) The resulting estimate of the geomagnetic field and its secular variation was propogated four years past the data to the time of the MAGSAT data. The accuracy with which this field model matched the MAGSAT data was evaluated by comparisons with predictions from other pre-MAGSAT field models. The field estimate obtained by recursive estimation was found to be superior to all other models.

  18. Fluctuations in tides and geomagnetic variations

    NASA Astrophysics Data System (ADS)

    Kohsiek, A.; Kiefer, M.; Meek, C. E.; Manson, A. H.

    Middle atmosphere tidal winds and the daily geomagnetic Sq-variation show a day-to-day variability, both with a local behaviour. Due to the main cause of the Sq-variation, the ionospheric dynamo effect, day-to-day fluctuation of Sq could be raised by fluctuations in tides. This coupling of fluctuations is investigated with radar wind data measured at Saskatoon at around 100 km height and with magnetic data from four observatories in the vicinity of the radar. We show that our definition of fluctuations exhibits properties of atmospheric tides in the winds and that the magnetic data can be assumed to represent a local behaviour. We find that there are some significant correlations between fluctuations in winds and magnetic variations. Apparently the local fluctuation of geomagnetic variations is weakly coupled not only to the fluctuations of the semidiurnal tides but also to those of the mean winds.

  19. Solar wind charge exchange during geomagnetic storms

    NASA Astrophysics Data System (ADS)

    Robertson, I. P.; Cravens, T. E.; Sibeck, D. G.; Collier, M. R.; Kuntz, K. D.

    2012-04-01

    On 2001 March 31 a coronal mass ejection pushed the subsolar magnetopause to the vicinity of geosynchronous orbit at 6.6 R_E. The NASA/GSFC Community Coordinated Modeling Center (CCMC) employed a global magnetohydrodynamic (MHD) model to simulate the solar wind-magnetosphere interaction during the peak of this geomagnetic storm. Robertson et al. then modeled the expected soft X-ray emission due to solar wind charge exchange with geocoronal neutrals in the dayside cusp and magnetosheath. The locations of the bow shock, magnetopause and cusps were clearly evident in their simulations. Another geomagnetic storm took place on 2000 July 14 (Bastille Day). We again modeled X-ray emission due to solar wind charge exchange, but this time as observed from a moving spacecraft. This paper discusses the impact of spacecraft location on observed X-ray emission and the degree to which the locations of the bow shock and magnetopause can be detected in images.

  20. MAGSAT for geomagnetic studies over Indian region

    NASA Technical Reports Server (NTRS)

    Rastogi, R. G.; Bhargava, B. N.; Singh, B. P.; Rao, D. R. K.; Rangarajan, G. K.; Rajaram, R.; Roy, M.; Arora, B. R.; Seth, A. (Principal Investigator)

    1981-01-01

    Progress in the preparation of software for converting data tapes produced on an IBM system to data readable on a DEC-10 system, in the creation of awareness of the utility of MAGSAT data among users in India, and in making computer programs supplied by NASA operational on the DEC-10 system is reported. Papers presented to Indian users, at the IAGA fourth scientific assembly, at a symposium on interdisciplinary approaches to geomagnetism, and a paper published in Science Today are included.

  1. NOAA Plans for Geomagnetic Storm Observations

    NASA Astrophysics Data System (ADS)

    Diedrich, B. L.; Biesecker, D. A.; Mulligan, P.; Simpson, M.

    2012-12-01

    For many years, NOAA has issued geomagnetic storm watches and warnings based on coronal mass ejection (CME) imagery and in-situ solar wind measurements from research satellites. The NOAA Satellite and Information Service (NESDIS) recognizes the importance of this service to protecting technological infrastructure including power grids, polar air travel, and satellite navigation, so is actively planning to replace these assets to ensure their continued availability. NOAA, NASA, and the US Air Force are working on launching the first operational solar wind mission in 2014, the Deep Space Climate Observatory (DSCOVR), to follow NASA's Advanced Composition Explorer (ACE) in making solar wind measurements at the sun-Earth L1 for 15-60 minute geomagnetic storm warning. For continuing operations after the DSCOVR mission, one technology NOAA is looking at is solar sails that could greatly improve the lead time of geomagnetic storm warnings by stationkeeping closer to the sun than L1. We are working with NASA and private industry on the Sunjammer solar sail demonstration mission to test making solar wind measurements from a solar sail in the sun-Earth L1 region. NOAA uses CME imagery from the NASA/ESA Solar and Heliospheric Observatory (SOHO) and the NASA Solar Terrestrial Relations Observatory (STEREO) satellites to issue 1-3 day geomagnetic storm watches. For the future, NOAA worked with the Naval Research Laboratory (NRL) to develop a Compact Coronagraph (CCOR) through Phase A, and is studying ways to complete instrument development and test fly it for use in the future.

  2. Geomagnetic Jerks in the Swarm Era

    NASA Astrophysics Data System (ADS)

    Brown, William; Beggan, Ciaran; Macmillan, Susan

    2016-08-01

    The timely provision of geomagnetic observations as part of the European Space Agency (ESA) Swarm mission means up-to-date analysis and modelling of the Earth's magnetic field can be conducted rapidly in a manner not possible before. Observations from each of the three Swarm constellation satellites are available within 4 days and a database of close-to-definitive ground observatory measurements is updated every 3 months. This makes it possible to study very recent variations of the core magnetic field. Here we investigate rapid, unpredictable internal field variations known as geomagnetic jerks. Given that jerks represent (currently) unpredictable changes in the core field and have been identified to have happened in 2014 since Swarm was launched, we ask what impact this might have on the future accuracy of the International Geomagnetic Reference Field (IGRF). We assess the performance of each of the IGRF-12 secular variation model candidates in light of recent jerks, given that four of the nine candidates are novel physics-based predictive models.

  3. AI techniques in geomagnetic storm forecasting

    NASA Astrophysics Data System (ADS)

    Lundstedt, Henrik

    This review deals with how geomagnetic storms can be predicted with the use of Artificial Intelligence (AI) techniques. Today many different Al techniques have been developed, such as symbolic systems (expert and fuzzy systems) and connectionism systems (neural networks). Even integrations of AI techniques exist, so called Intelligent Hybrid Systems (IHS). These systems are capable of learning the mathematical functions underlying the operation of non-linear dynamic systems and also to explain the knowledge they have learned. Very few such powerful systems exist at present. Two such examples are the Magnetospheric Specification Forecast Model of Rice University and the Lund Space Weather Model of Lund University. Various attempts to predict geomagnetic storms on long to short-term are reviewed in this article. Predictions of a month to days ahead most often use solar data as input. The first SOHO data are now available. Due to the high temporal and spatial resolution new solar physics have been revealed. These SOHO data might lead to a breakthrough in these predictions. Predictions hours ahead and shorter rely on real-time solar wind data. WIND gives us real-time data for only part of the day. However, with the launch of the ACE spacecraft in 1997, real-time data during 24 hours will be available. That might lead to the second breakthrough for predictions of geomagnetic storms.

  4. Geomagnetic secular variation in the Indian Ocean

    NASA Astrophysics Data System (ADS)

    Heirtzler, J. R.; Nazarova, K.

    2003-02-01

    Annual repeat stations in Australia and in South Africa show that secular variation may change rapidly and over short geographical distances in the Indian Ocean area. Satellite models show large secular variations in the center of the Indian Ocean where there are few island geomagnetic observatories. This paper investigates marine geomagnetic measurements to see if they give more information about secular variations in this area. Between 1960 and 1988 there were more than 70 port-to-port cruises with ships towing proton precession magnetometers in the Indian Ocean. Change in field intensity from one cruise to another provides new information about the secular variation in this part of the world. Several methods were investigated to determine this change from the ship's data. Observing the change on closely parallel or crossing tracks provides an estimate of this change. These results indicate that there are short time and distance scales of secular variation in the Indian Ocean which have not been accounted for in geomagnetic field models.

  5. Domino model for geomagnetic field reversals.

    PubMed

    Mori, N; Schmitt, D; Wicht, J; Ferriz-Mas, A; Mouri, H; Nakamichi, A; Morikawa, M

    2013-01-01

    We solve the equations of motion of a one-dimensional planar Heisenberg (or Vaks-Larkin) model consisting of a system of interacting macrospins aligned along a ring. Each spin has unit length and is described by its angle with respect to the rotational axis. The orientation of the spins can vary in time due to spin-spin interaction and random forcing. We statistically describe the behavior of the sum of all spins for different parameters. The term "domino model" in the title refers to the interaction among the spins. We compare the model results with geomagnetic field reversals and dynamo simulations and find strikingly similar behavior. The aggregate of all spins keeps the same direction for a long time and, once in a while, begins flipping to change the orientation by almost 180 degrees (mimicking a geomagnetic reversal) or to move back to the original direction (mimicking an excursion). Most of the time the spins are aligned or antialigned and deviate only slightly with respect to the rotational axis (mimicking the secular variation of the geomagnetic pole with respect to the geographic pole). Reversals are fast compared to the times in between and they occur at random times, both in the model and in the case of the Earth's magnetic field.

  6. Solar generated quasi-biennial geomagnetic variation

    NASA Technical Reports Server (NTRS)

    Sugiura, M.; Poros, D. J.

    1977-01-01

    The existence of highly correlated quasi-biennial variations in the geomagnetic field and in solar activity is demonstrated. The analysis uses a numerical filter technique applied to monthly averages of the geomagnetic horizontal component and of the Zurich relative sunspot number. Striking correlations are found between the quasi-biennial geomagnetic variations determined from several magnetic observatories located at widely different longitudes, indicating a worldwide nature of the obtained variation. The correlation coefficient between the filtered Dst index and the filtered relative sunspot number is found to be -0.79 at confidence level greater than 99% with a time-lag of 4 months, with solar activity preceding the Dst variation. The correlation between the unfiltered data of Dst and of the sunspot number is also high with a similar time-lag. Such a timelag has not been discussed in the literature, and a further study is required to establish the mode of sun-earth relationship that gives this time delay.

  7. Geomagnetic Field Response at Southern and Northern Hemisphere

    NASA Astrophysics Data System (ADS)

    Chandel, Babita

    Geomagnetic Field Response at Southern and Northern Hemisphere Babita Chandel, Shailendra Saini, Sneha Yadav,S.K.Vijay and A.K.Gwal Space Science Laboratory, Department of Physics, Barkatullah University, Bhopal-462026, India ABSTRACT: This paper represents the geomagnetic field response at Southern Hemisphere (MAITRI) and Northern Hemisphere (TROMSO). The Indian Antarctic Station MAITRI is located at geomagnetic Long. (66.030, 53.210) where as TROMSO is at geomagnetic Long. (66.030, 53.210). We studied the behaviour of geomagnetic field with respect to geomagnetic storms at both the stations TROMSO and MAITRI. It was observed that at Southern Hemisphere there is more variation in winter as compared to the summer season, where as in Northern Hemisphere the variations are more in summer as compared to winter. As in the Northern hemisphere the magnetospheric plasma is strongly turbulized in summer and in Southern hemisphere the magentospheric plasma is strongly turbulized in winter.

  8. A sensitive geomagnetic activity index for space weather operation

    NASA Astrophysics Data System (ADS)

    Du, D.; Xu, W. Y.; Zhao, M. X.; Chen, B.; Lu, J. Y.; Yang, G. L.

    2010-12-01

    There is an ongoing demand for real-time geomagnetic indices in space services. The traditional 3 h K index and K-derived planetary indices cannot issue alters promptly during large storms, and the 3 h interval is much larger than the time scales of ionospheric responses. To overcome these difficulties, we define a new consecutive and linear geomagnetic activity index, the range of hourly H component index (rH) with 1 min resolution, and develop a local rH index nowcast system for space weather operation, which can issue geomagnetic storm alerts quickly. We also derive Kp/Ap indices conveniently from a single station data to describe the global geomagnetic activity. Then we make a statistic comparison between rH and other definite index values during storm and find that rH is sensitive to the geomagnetic disturbance and can reflect the geomagnetic activity more delicately.

  9. Torsional rigidity, isospectrality and quantum graphs

    NASA Astrophysics Data System (ADS)

    Colladay, Don; Kaganovskiy, Leon; McDonald, Patrick

    2017-01-01

    We study torsional rigidity for graph and quantum graph analogs of well-known pairs of isospectral non-isometric planar domains. We prove that such isospectral pairs are distinguished by torsional rigidity.

  10. Interplanetary magnetic sector polarity inferred from polar geomagnetic field observations

    NASA Technical Reports Server (NTRS)

    Friis-Christensen, E.; Lassen, K.; Wilcox, J. M.; Gonzalez, W.; Colburn, D. S.

    1971-01-01

    In order to infer the interplanetary sector polarity from polar geomagnetic field diurnal variations, measurements were carried out at Godhavn and Thule (Denmark) Geomagnetic Observatories. The inferred interplanetary sector polarity was compared with the polarity observed at the same time by Explorer 33 and 35 magnetometers. It is shown that the polarity (toward or away from the sun) of the interplanetary magnetic field can be reliably inferred from observations of the polar cap geomagnetic fields.

  11. Has the Next Geomagnetic Field Reversal Already Started?

    NASA Astrophysics Data System (ADS)

    de Santis, A.; Tozzi, R.; Wicht, J.

    2004-05-01

    Although in the past some speculations about an occurring geomagnetic field reversal were already formulated, only recently this has emerged as a really constructive hypothesis to be better investigated. From Information Content analysis of global models of the geomagnetic field and geodynamo simulations, it results that within 1000-1500 years the geomagnetic field will likely change its polarity. In this work we will present some considerations that support this possibility together with their geophysical implications.

  12. Geomagnetic excursions date early hominid migration to China

    NASA Astrophysics Data System (ADS)

    Bhattacharya, Atreyee

    2012-09-01

    Global-scale geomagnetic reversals, which are periods when the direction of Earth's magnetic field flips, leave imprints in magnetic minerals present in sediments. But so do smaller-scale, even local, changes in Earth's magnetic field direction. Paleomagnetists believe that the smaller-scale events represent “failed reversals” and refer to them as “geomagnetic excursions.” Scientists use geomagnetic excursions in sedimentary basins as markers to tie together events of Earth's history across the globe.

  13. Associative memory through rigid origami

    NASA Astrophysics Data System (ADS)

    Murugan, Arvind; Brenner, Michael

    2015-03-01

    Mechanisms such as Miura Ori have proven useful in diverse contexts since they have only one degree of freedom that is easily controlled. We combine the theory of rigid origami and associative memory in frustrated neural networks to create structures that can ``learn'' multiple generic folding mechanisms and yet can be robustly controlled. We show that such rigid origami structures can ``recall'' a specific learned mechanism when induced by a physical impulse that only need resemble the desired mechanism (i.e. robust recall through association). Such associative memory in matter, seen before in self-assembly, arises due to a balance between local promiscuity (i.e., many local degrees of freedom) and global frustration which minimizes interference between different learned behaviors. Origami with associative memory can lead to a new class of deployable structures and kinetic architectures with multiple context-dependent behaviors.

  14. Geomagnetic field models incorporating physical constraints on the secular variation

    NASA Technical Reports Server (NTRS)

    Constable, Catherine; Parker, Robert L.

    1993-01-01

    This proposal has been concerned with methods for constructing geomagnetic field models that incorporate physical constraints on the secular variation. The principle goal that has been accomplished is the development of flexible algorithms designed to test whether the frozen flux approximation is adequate to describe the available geomagnetic data and their secular variation throughout this century. These have been applied to geomagnetic data from both the early and middle part of this century and convincingly demonstrate that there is no need to invoke violations of the frozen flux hypothesis in order to satisfy the available geomagnetic data.

  15. International geomagnetic reference field 1965.0 in dipole coordinates

    NASA Technical Reports Server (NTRS)

    Mead, G. D.

    1970-01-01

    Computer program transforming spherical harmonic coefficients into arbitrarily tilted coordinate systems, tabulating coefficients of International Geomagnetic Reference Field 1965 in dipole coordinate system

  16. Rotating rigid motion in general relativity

    SciTech Connect

    Mason, D.P.; Pooe, C.A.

    1987-11-01

    Kinematic and dynamic expressions are derived for the Lie derivative of vorticity along a particle world line in a rigid motion. It is found that the evolution of vorticity in a rigid motion is governed by the electric part of the Weyl tensor. Necessary and sufficient kinematic and dynamic conditions are established for a rotating rigid motion to be isometric.

  17. Geomagnetically Induced Currents, a space weather hazard. Case study - Europe under intense geomagnetic storms of the solar cycle 23

    NASA Astrophysics Data System (ADS)

    Dobrica, V.; Demetrescu, Cr.; Stefan, C.; Greculeasa, R.

    2016-05-01

    The interaction of the solar wind and heliospheric magnetic field with the magnetosphere and ionosphere results in variations of the geomagnetic field that induce hazardous electric currents in grounded technological systems (electric power and hydrocarbon transportation networks), the so-called geomagnetically induced currents (GICs). In order to evaluate the hazard induced on the European continent, we present a study of the surface electric field induced by 16 intense (Dst < -150 nT) geomagnetic storms, based on the analysis of the geomagnetic records from the European network of observatories, study that tend to solve the geophysical part of the problem. The evolution during storm development and the sources of the disturbance field are explored in case of the largest geomagnetic storm in the cycle 23 (Dst = -422 nT, November 20-21, 2003), and the geographical distribution of the maximum induced surface geoelectric field over Europe by the 16 storms considered in the study is presented. As source proxies, the Dst geomagnetic index, showing the disturbed field produced by the magnetospheric ring current at the geomagnetic equator, the AL geomagnetic index, showing the disturbed field produced by the ionospheric electrojet at auroral latitude, and the PC geomagnetic index, showing the disturbed field produced by the polar cap current, were examined.

  18. A study of the composition and energy spectra of anomalous cosmic rays using the geomagnetic field

    SciTech Connect

    Mewaldt, R.A.; Cummings, J.R.; Leske, R.A.; Selesnick, R.S.; Stone, E.C.

    1996-03-15

    The authors use instrumentation on SAMPEX and the Earth`s field as a magnetic rigidity filter in a {open_quotes}double spectrometer{close_quotes} approach to measure the composition and energy spectra of anomalous cosmic rays (ACRs) with Z>6. A {open_quotes}pure{close_quotes} sample of anomalous cosmic ray C, N, O, and Ne is obtained, with no significant evidence for other species. The bulk of ACRs are now known to be singly-charged, and the geomagnetic filter allows their energy spectra to be measured to higher energies than before. The anomalous oxygen spectrum is found to extend to at least {approx} 100 MeV/nuc, which has implications for models of the acceleration of these ions. 27 refs., 3 fig., 1 tab.

  19. On the scaling features of high-latitude geomagnetic field fluctuations during a large geomagnetic storm

    NASA Astrophysics Data System (ADS)

    De Michelis, Paola; Federica Marcucci, Maria; Consolini, Giuseppe

    2015-04-01

    Recently we have investigated the spatial distribution of the scaling features of short-time scale magnetic field fluctuations using measurements from several ground-based geomagnetic observatories distributed in the northern hemisphere. We have found that the scaling features of fluctuations of the horizontal magnetic field component at time scales below 100 minutes are correlated with the geomagnetic activity level and with changes in the currents flowing in the ionosphere. Here, we present a detailed analysis of the dynamical changes of the magnetic field scaling features as a function of the geomagnetic activity level during the well-known large geomagnetic storm occurred on July, 15, 2000 (the Bastille event). The observed dynamical changes are discussed in relationship with the changes of the overall ionospheric polar convection and potential structure as reconstructed using SuperDARN data. This work is supported by the Italian National Program for Antarctic Research (PNRA) - Research Project 2013/AC3.08 and by the European Community's Seventh Framework Programme ([FP7/2007-2013]) under Grant no. 313038/STORM and

  20. Geomagnetic imprint of the Persani volcanism

    NASA Astrophysics Data System (ADS)

    Besutiu, Lucian; Seghedi, Ioan; Zlagnean, Luminita; Atanasiu, Ligia; Popa, Razvan-Gabriel; Pomeran, Mihai; Visan, Madalina

    2016-04-01

    The Persani small volume volcanism is located in the SE corner of the Transylvanian Depression, at the north-western edge of the intra-mountainous Brasov basin. It represents the south-easternmost segment of the Neogene-Quaternary volcanic chain of the East Carpathians. The alkaline basalt monogenetic volcanic field is partly coeval with the high-K calc-alkaline magmatism south of Harghita Mountains (1-1.6 Ma). Its eruptions post-dated the calc-alkaline volcanism in the Harghita Mountains (5.3-1.6 Ma), but pre-dated the high-K calc-alkaline emissions of Ciomadul volcano (1.0-0.03 Ma). The major volcanic forms have been mapped in previous geological surveys. Still, due to the small size of the volcanoes and large extent of tephra deposits and recent sediments, the location of some vents or other volcanic structures has been incompletely revealed. To overcome this problem, the area was subject to several near-surface geophysical investigations, including paleomagnetic research. However, due to their large-scale features, the previous geophysical surveys proved to be an inappropriate approach to the volcanological issues. Therefore, during the summers of 2014 and 2015, based on the high magnetic contrast between the volcanic rocks and the hosting sedimentary formations, a detailed ground geomagnetic survey has been designed and conducted, within central Persani volcanism area, in order to outline the presence of volcanic structures hidden beneath the overlying deposits. Additionally, information on the rock magnetic properties was also targeted by sampling and analysing several outcrops in the area. Based on the acquired data, a detailed total intensity scalar geomagnetic anomaly map was constructed by using the recent IGRF12 model. The revealed pattern of the geomagnetic field proved to be fully consistent with the direction of magnetisation previously determined on rock samples. In order to enhance the signal/noise ratio, the results were further processed by

  1. Historical variation of the geomagnetic axial dipole

    NASA Astrophysics Data System (ADS)

    Finlay, Christopher C.

    2008-09-01

    The geomagnetic axial dipole (hereinafter denoted g10) is the largest component of our planet's magnetic field. Its magnitude determines the morphology of solar-terrestrial electrical current systems and it is the most fundamental diagnostic property of the core-generated geodynamo. Elucidating past and future variations of g10(t) is consequently of central importance in geomagnetism. Previous historical geomagnetic field models, such as gufm1 of Jackson et al. [Jackson, A., Jonkers, A.R.T., Walker, M.R., 2000. Four centuries of geomagnetic secular variation from historical records. Philos. Trans. R. Soc. Lond. A 358, 957-990], used direct observations to constrain g10(t) only after 1840 A.D.; before this time a crude linear extrapolation of the post-1840 A.D. rate of change (15 nT/year) was employed. In this contribution I construct historical field models with g10(t) instead constrained from 1590 A.D. to 1840 A.D. by an archaeointensity dataset compiled by Korte et al. [Korte, M., Genevey, A., Constable, C.G., Frank, U., Schnepp, E., 2005. Continuous geomagnetic field models for the past 7 millennia. 1. A new global data compilation. Geochem. Geophys. Geosyst. 6, doi:10.1029/2004GC000800]. A range of possible linear models of the form g10(t)=g10(1840)+β(t-1840) are first explored; β=2.74±42.32 nT/year is found to explain the archaeointensity dataset with maximum likelihood, consistent with the recent findings of Gubbins et al. [Gubbins, D., Jones, A.L., Finlay, C.C., 2006. Fall in Earth's magnetic field is erratic. Science 312, 900-902]. Relaxing the linear constraint in an effort to find more physically plausible models, I find it is necessary to artificially increase the weight given to the archaeointensity data in order to obtain acceptable models. Despite satisfactorily explaining both the historical and archaeointensity data, and possessing reasonable spatial and temporal complexity, such free evolution models perform worse than the simpler linearly

  2. Analysis of geomagnetic secular variation during 1980-1985 and 1985- 1990, and geomagnetic models proposed for the 1991 revision of the International Geomagnetic Reference Field

    USGS Publications Warehouse

    Peddie, N.W.

    1992-01-01

    The secular variation of the main geomagnetic field during the periods 1980-1985 and 1985-1990 was analyzed in terms of spherical harmonics up to the eighth degree and order. Data from worldwide magnetic observatories and the Navy's Project MAGNET aerial surveys were used. The resulting pair of secular-variation models was used to update the Definitive Geomagnetic Reference Field (DGRF) model for 1980, resulting in new mainfield models for 1985.0 and 1990.0. These, along with the secular-variation model for 1985-1990, were proposed for the 1991 revision of the International Geomagnetic Reference Field (IGRF). -Author

  3. Rigid zeolite containing polyurethane foams

    DOEpatents

    Frost, C.B.

    1984-05-18

    A closed cell rigid polyurethane foam has been prepared which contains up to about 60% by weight of molecular sieves capable of sorbing molecules with effective critical diameters of up to about 10 A. The molecular sieve component of the foam can be preloaded with catalysts or with reactive compounds that can be released upon activation of the foam to control and complete crosslinking after the foam is formed. The foam can also be loaded with water or other flame-retarding agents, after completion. Up to about 50% of the weight of the isocyanate component of the foam can be replaced by polyimide resin precursors for incorporation into the final polymeric network.

  4. Rigid separator lead acid batteries

    SciTech Connect

    Cannone, A.G.; Salkind, A.J.; Stempin, J.L.; Wexell, D.R.

    1996-11-01

    Lead acid cells assembled with extruded separators displayed relatively uniform capacity and voltage parameters through 100{sup +} cycles of charge/discharge. This contrasts to failure of control cells with glass mat separators after 60 cycles. The mullite/alumina separators with 50, 60, and 70% porosity separators appear suitable for both flooded and sealed lead acid cell applications. The advantages of the rigid ceramic separators over fiber mat materials are in the uniformity of capacity and voltage, the ease of cell assembly, and the probability that firm stacking pressure on the active material will yield greater cycle life, especially at elevated temperatures.

  5. Rigid zeolite containing polyurethane foams

    DOEpatents

    Frost, Charles B.

    1985-01-01

    A closed cell rigid polyurethane foam has been prepared which contains up to about 60% by weight of molecular sieves capable of sorbing molecules with effective critical diameters of up to about 10 .ANG.. The molecular sieve component of the foam can be preloaded with catalysts or with reactive compounds that can be released upon activation of the foam to control and complete crosslinking after the foam is formed. The foam can also be loaded with water or other flame-retarding agents, after completion. Up to about 50% of the weight of the isocyanate component of the foam can be replaced by polyimide resin precursors for incorporation into the final polymeric network.

  6. Lubrication of rigid ellipsida solids

    NASA Technical Reports Server (NTRS)

    Hamrock, B. J.; Dowson, D.

    1982-01-01

    The influence of geometry on the isothermal hydrodynamic film separating two rigid solids was investigated. The minimum film thickness is derived for fully flooded conjunctions by using the Reynolds boundary conditions. It was found that the minimum film thickness had the same speed, viscosity, and load dependence as Kapitza' classical solution. However, the incorporation of Reynolds boundary conditions resulted in an additional geometry effect. Solutions using the parabolic film approximation are compared by using the exact expression for the film in the analysis. Contour plots are known that indicate in detail the pressure developed between the solids.

  7. Geomagnetically Induced Currents: Progress and Issues

    NASA Astrophysics Data System (ADS)

    Thomson, Alan

    2010-05-01

    Geomagnetically induced currents (GIC) are a hazard to conducting networks such as high-voltage power and pipeline grids. GIC have been known for decades to affect power systems at higher latitudes (e.g. Europe and North America), although more recently GIC have also been found to affect power networks at middle and lower latitudes. Mitigating the effects of GIC remains an issue for the power and pipeline industries and for governments concerned with the societal and economic implications. To understand, e.g. to model and predict, GIC in conducting grids needs expertise drawn from electrical engineering, geophysics and space weather science - a truly multi-disciplinary undertaking. In terms of geophysics and space physics, issues such as Earth structure (e.g. 3D versus 1D mantle and lithospheric conductivity structure), ocean/continent conductivity contrasts, ionospheric current systems and their variability and Sun-Earth magnetic interactions are all relevant. The start of solar cycle 24 provides an opportune time to consider the status of GIC research and to assess what new studies are required in geophysical modelling and in hazard analysis. What do we need to improve on to better specify/predict GIC flowing in power grids, from ‘up-stream' observations of coronal mass ejections through to geomagnetic field measurements made during magnetic storms? In this invited review we will consider aspects of a) Measurement: how do we measure GIC in grids; b) Analysis: how do measured GIC relate to geophysical and space physics data; c) Modelling: what methods exist for modelling GIC, again in relation to other data, and how accurate are models; and d) Prediction: how predictable are GIC and what are the implications for, e.g., the power industry and national governments. We will review the more recent developments in GIC and related geomagnetism and space weather science. We will outline what issues are widely believed to now be understood and what issues remain to be

  8. Long persistence effects of geomagnetic activity

    NASA Astrophysics Data System (ADS)

    Wrenn, Gordon L.

    1990-03-01

    The identification of the physical processes which perturb the dynamic equilibrium of the charged particle populations in the terrestrial magnetosphere is investigated. A planetary index was used and it was proved that the introduction of a persistence factor for a derived index, a time weighted accumulation of recent values, gives a better correlation with an estimation of characteristic persistence times in order to establish the temporal response of observed effects in relation to available measures of geomagnetic activity. The analysis procedure was illustrated by results pertaining to ionospheric foF2, cold plasma concentration at geosynchronous orbit and ring current strength.

  9. Interplanetary magnetic field and geomagnetic Dst variations.

    NASA Technical Reports Server (NTRS)

    Patel, V. L.; Desai, U. D.

    1973-01-01

    The interplanetary magnetic field has been shown to influence the ring current field represented by Dst. Explorer 28 hourly magnetic field observations have been used with the hourly Dst values. The moderate geomagnetic storms of 60 gammas and quiet-time fluctuations of 10 to 30 gammas are correlated with the north to south change of the interplanetary field component perpendicular to the ecliptic. This change in the interplanetary field occurs one to three hours earlier than the corresponding change in the Dst field.

  10. Halo Coronal Mass Ejections and Geomagnetic Storms

    NASA Technical Reports Server (NTRS)

    Gopalswamy, Nat

    2009-01-01

    In this letter, I show that the discrepancies in the geoeffectiveness of halo coronal mass ejections (CMEs) reported in the literature arise due to the varied definitions of halo CMEs used by different authors. In particular, I show that the low geoeffectiveness rate is a direct consequence of including partial halo CMEs. The geoeffectiveness of partial halo CMEs is lower because they are of low speed and likely to make a glancing impact on Earth. Key words: Coronal mass ejections, geomagnetic storms, geoeffectiveness, halo CMEs.

  11. Geomagnetic field behaviour preceding a Superchron: new evidence for a weak Devonian geomagnetic field

    NASA Astrophysics Data System (ADS)

    Hawkins, L.; Anwar, T.; Scherbakova, V.; Biggin, A. J.; Kravchinsky, V. A.; Shatsillo, A.; Holt, J.; Pavlov, V.

    2015-12-01

    The ~50 million year transition from the peak in reversal frequency in the Middle Jurassic (~170Ma), associated with a weak geomagnetic field, to the stable and apparently strong field during the Cretaceous Normal Superchron (84-121Ma), represents a dramatic change in time-averaged geomagnetic field behaviour during the Mesozoic Era. New evidence from Siberian samples suggests there is a similar transition in geomagnetic field behaviour during the Palaeozoic, with a weak geomagnetic field in the Upper Devonian preceding the Permo-Carboniferous Superchron (262-318Ma). Both sites, the Viluy Traps and the Zharovsk complex of the Patom Margin, have seemingly reliable, published palaeomagnetic directions and new age constraints, 364.4 ± 1.7Ma (40Ar/39A) 371-377Ma (U-Pb) respectively. The samples were measured using the Thermal Thellier-Coe protocol with partial thermo-remanent magnetisation (pTRM) and tail checks and the Microwave Thellier-IZZI protocol with pTRM checks. Accepted Arai plots show positive pTRM checks, a clear relation between distinct primary directional and palaeointensity components and little to no zig-zagging. Three distinct magneto-mineralogical types were identified from SEM and rock magnetic techniques; low Ti- and intermediate Ti- titanomagnetite and possible maghemite, with mineral type affecting the success rate of samples but resulting in no significant variation in palaeointensity results. The Arai plots also commonly have a distinct two-slope concave-up shape, although non-heating, pseudo-Thellier experiments have supported this resulting from a strong overprint component rather than alteration or multi-domain effects. Results from these experiments give low site mean values between 2.3-29.9μT (Virtual Dipole Moments 4-50.6 ZAm2). The apparently periodic (~180 million years) transitions in geomagnetic field behaviour may indicate the influence of mantle convection changing heat flow across the Core Mantle Boundary.

  12. Major geomagnetic storm due to solar activity (2006-2013).

    NASA Astrophysics Data System (ADS)

    Tiwari, Bhupendra Kumar

    Major geomagnetic storm due to solar activity (2006-2013). Bhupendra Kumar Tiwari Department of Physics, A.P.S.University, Rewa(M.P.) Email: - btiwtari70@yahoo.com mobile 09424981974 Abstract- The geospace environment is dominated by disturbances created by the sun, it is observed that coronal mass ejection (CME) and solar flare events are the causal link to solar activity that produces geomagnetic storm (GMS).CMEs are large scale magneto-plasma structures that erupt from the sun and propagate through the interplanetary medium with speeds ranging from only a few km/s to as large as 4000 km/s. When the interplanetary magnetic field associated with CMEs impinges upon the earth’s magnetosphere and reconnect occur geomagnetic storm. Based on the observation from SOHO/LASCO spacecraft for solar activity and WDC for geomagnetism Kyoto for geomagnetic storm events are characterized by the disturbance storm time (Dst) index during the period 2006-2013. We consider here only intense geomagnetic storm Dst <-100nT, are 12 during 2006-2013.Geomagnetic storm with maximum Dst< -155nT occurred on Dec15, 2006 associated with halo CME with Kp-index 8+ and also verify that halo CME is the main cause to produce large geomagnetic storms.

  13. Empirical analytic transformations between geographic and corrected geomagnetic coordinates

    NASA Technical Reports Server (NTRS)

    Comfort, R. H.

    1970-01-01

    Based upon a mathematical model of contours of constant corrected geomagnetic latitude in a polar projection of geographic coordinates, analytic equations are developed for converting geographic coordinates to corrected geomagnetic coordinates and vice versa. The equations were programmed for use on a small computer. This treatment is restricted to the Northern Hemisphere.

  14. Search for correlation between geomagnetic disturbances and mortality

    NASA Technical Reports Server (NTRS)

    Lipa, B. J.; Barnes, C. W.; Sturrock, P. A.; Feinleib, M.; Rogot, E.

    1975-01-01

    Statistical evaluation of death rates in the U.S.A. from heart diseases or stroke did not show any correlation with measured geomagnetic pulsations and thus do not support a claimed relationship between geomagnetic activity and mortality rates to low frequency fluctuations of the earth's magnetic field.

  15. The use of geomagnetic field models in magnetic surveys

    NASA Technical Reports Server (NTRS)

    Regan, R. D.; Gain, J. C.

    1974-01-01

    The importance of global geomagnetic field models for the reduction of magnetic surveys is discussed. It is demonstrated that a numerical model with adequate secular variation correction, provides a suitable representation of the regional field. The limitations of the presently available models are reported, with emphasis on the International Geomagnetic Reference Field.

  16. Geomagnetic disturbances imprints in ground and satellite altitude observatories

    NASA Astrophysics Data System (ADS)

    Yahiat, Yasmina; Lamara, Souad; Zaourar, Naima; Hamoudi, Mohamed

    2016-04-01

    The temporal evolution of the geomagnetic field and its variations have been repeatedly studied from both ground observatories and near-earth orbiting platforms. With the advent of the space ageand the launches of geomagnetic low altitude orbits satellites, a global coverage has been achieved. Since Magsat mission, more satellites were put into orbit and some of them are still collecting data enhancing the spatial and temporal descriptions of the field. Our study uses new data gathered by the latest SWARM satellite mission launched on November, 22nd 2013. It consists of a constellation of three identical satellites carrying on board high resolution and accuracy scientific equipment. Data from this constellation will allow better understanding the multiscale behavior of the geomagnetic field. Our goal is to analyze and interpret the geomagnetic data collected by this Swarm mission, for a given period and try to separate the external disturbances from internal contributions. We consider in the study the variation of the horizontal component H, for different virtual geomagnetic observatories at the satellite altitude. The analysis of data by Swarm orbital segments shows clearly the external disturbances of the magnetic field like that occurring on 27th of August 2014. This perturbation is shown on geomagnetic indexes and is related to a coronal mass ejection (CME). These results from virtual observatories are confirmed, by the equivalent analysis using ground observatories data for the same geographic positions and same epochs. Key words: Geomagnetic field, external field, geomagnetic index, SWARM mission, virtual observatories.

  17. Science outreach and capacity building in geomagnetism and space sciences—An Indian Institute of Geomagnetism endeavor

    NASA Astrophysics Data System (ADS)

    Gawali, Praveen; Bhaskar, Ankush; Dhar, Ajay; Ramesh, Durbha Sai

    2016-05-01

    We present an overview of science outreach and capacity building activities at the Indian Institute of Geomagnetism (IIG) against the backdrop of a long history of geomagnetic studies. We also present the future plans of the institute for strengthening these activities.

  18. Geomagnetic excursions reflect an aborted polarity state

    NASA Astrophysics Data System (ADS)

    Valet, Jean-Pierre; Plenier, Guillaume; Herrero-Bervera, E.

    2008-10-01

    Geomagnetic excursions represent short episodes of a few thousand years at most during which the field considerably exceeds its normal range of variability during a polarity state. Paleomagnetic records have now been obtained with extremely high temporal resolution which have improved our knowledge of these short events. We have compiled the most detailed records of excursions that had occurred during the Brunhes and Matuyama chrons. We show that virtual geomagnetic poles (VGPs) of at least one record of each event are able to reach the opposite polarity. In the next step, we have computed different simulations of excursions during which the dipole progressively vanishes before growing back without reversing. This scenario produces very few reversed directions which are only visible at some latitudes. We infer that it is impossible to reach the ratio of reversed to intermediate VGPs present in the paleomagnetic records if the excursions were not associated with a short period of reversed dipole field. Therefore, excursions should be regarded as two successive reversals bracketing an aborted polarity interval. We propose that the same underlying mechanisms prevail in both situations (excursions or reversals) and that below a certain strength the field reaches an unstable position which preludes either the achievement of a reversal or its return to the former polarity.

  19. Solar Wind Charge Exchange During Geomagnetic Storms

    NASA Technical Reports Server (NTRS)

    Robertson, Ina P.; Cravens, Thomas E.; Sibeck, David G.; Collier, Michael R.; Kuntz, K. D.

    2012-01-01

    On March 31st. 2001, a coronal mass ejection pushed the subsolar magnetopause to the vicinity of geosynchronous orbit at 6.6 RE. The NASA/GSFC Community Coordinated Modeling Center (CCMe) employed a global magnetohydrodynamic (MHD) model to simulate the solar wind-magnetosphere interaction during the peak of this geomagnetic storm. Robertson et aL then modeled the expected 50ft X-ray emission due to solar wind charge exchange with geocoronal neutrals in the dayside cusp and magnetosheath. The locations of the bow shock, magnetopause and cusps were clearly evident in their simulations. Another geomagnetic storm took place on July 14, 2000 (Bastille Day). We again modeled X-ray emission due to solar wind charge exchange, but this time as observed from a moving spacecraft. This paper discusses the impact of spacecraft location on observed X-ray emission and the degree to which the locations of the bow shock and magnetopause can be detected in images.

  20. Atmospheric helium and geomagnetic field reversals.

    NASA Technical Reports Server (NTRS)

    Sheldon, W. R.; Kern, J. W.

    1972-01-01

    The problem of the earth's helium budget is examined in the light of recent work on the interaction of the solar wind with nonmagnetic planets. It is proposed that the dominant mode of helium (He4) loss is ion pumping by the solar wind during geomagnetic field reversals, when the earth's magnetic field is very small. The interaction of the solar wind with the earth's upper atmosphere during such a period is found to involve the formation of a bow shock. The penetration altitude of the shock-heated solar plasma is calculated to be about 700 km, and ionization rates above this level are estimated for a cascade ionization (electron avalanche) process to average 10 to the 9th power ions/sq cm/sec. The calculated ionization rates and the capacity of the solar wind to remove ionized helium (He4) from the upper atmosphere during geomagnetic dipole reversals are sufficient to yield a secular equilibrium over geologic time scales. The upward transport of helium from the lower atmosphere under these conditions is found to be adequate to sustain the proposed loss rate.

  1. Mooring and ground handling rigid airships

    NASA Technical Reports Server (NTRS)

    Walker, H., Jr.

    1975-01-01

    The problems of mooring and ground handling rigid airships are discussed. A brief history of Mooring and Ground Handling Rigid Airships from July 2, 1900 through September 1, 1939 is included. Also a brief history of ground handling developments with large U. S. Navy nonrigid airships between September 1, 1939 and August 31, 1962 is included wherein developed equipment and techniques appear applicable to future large rigid airships. Finally recommendations are made pertaining to equipment and procedures which appear desirable and feasible for future rigid airship programs.

  2. Studies on the Geomagnetic Induction Vectors of China

    NASA Astrophysics Data System (ADS)

    Wang, Qiao; Zhang, Huiqian; Huang, Qinghua

    2016-04-01

    In this study, the geomagnetic data of 16 stations, near 6 years for most, provided by the National Geomagnetic Center of China, were used to study on the geomagnetic induction vectors. The stations cover the whole North China and part of southwestern China, both of which has a complicate geological and tectonic background. This study will not only advance the understanding of regional tectonic variations, but also provide some suggestions on the construction for geomagnetic observation network of earthquake monitoring. The time series of geomagnetic induction vectors were obtained by the robust estimation method, which has been verified and compared with the ordinary least square and the weighted square method. A principle of selecting a specified period's results from the robust estimation method was defined. Then, the results with the period of 640s for all stations were selected by this principle. The long-term trends (more than six months at least) within the time series were extracted by the Fourier harmonic analysis. Consistent phase variations exist for most stations within a similar tectonic background. About one-month period variations in the most stations' results after removing the long-term trends were found. Spectrum analysis for the results and geomagnetic activity index showed that those phenomena may relate to the period of the global geomagnetic activity. A preference azimuth of the geomagnetic induction vectors was found in each station by statistical analysis on the time series. It pointed out the possible relatively high conductivity structures. Exactly, geomagnetic vectors of BJI, JIH, LYH and TAY station, which surround the basin of North China, suggested a relatively higher conductivity layer; that of stations around the Erdos block suggested a complicated structure. Three-dimension inversion by ModEM verifies our results.

  3. Geomagnetically induced currents in the Irish power network during geomagnetic storms

    NASA Astrophysics Data System (ADS)

    Blake, Seán. P.; Gallagher, Peter T.; McCauley, Joe; Jones, Alan G.; Hogg, Colin; Campanyà, Joan; Beggan, Ciarán. D.; Thomson, Alan W. P.; Kelly, Gemma S.; Bell, David

    2016-12-01

    Geomagnetically induced currents (GICs) are a well-known terrestrial space weather hazard. They occur in power transmission networks and are known to have adverse effects in both high-latitude and midlatitude countries. Here we study GICs in the Irish power transmission network (geomagnetic latitude 54.7-58.5°N) during five geomagnetic storms (6-7 March 2016, 20-21 December 2015, 17-18 March 2015, 29-31 October 2003, and 13-14 March 1989). We simulate electric fields using a plane wave method together with two ground resistivity models, one of which is derived from magnetotelluric measurements (magnetotelluric (MT) model). We then calculate GICs in the 220, 275, and 400 kV transmission network. During the largest of the storm periods studied, the peak electric field was calculated to be as large as 3.8 V km-1, with associated GICs of up to 23 A using our MT model. Using our homogenous resistivity model, those peak values were 1.46 V km-1 and 25.8 A. We find that three 400 and 275 kV substations are the most likely locations for the Irish transformers to experience large GICs.

  4. Search for correlation between geomagnetic disturbances and mortality

    NASA Technical Reports Server (NTRS)

    Lipa, B. J.; Sturrock, P. A.; Rogot, F.

    1976-01-01

    A search is conducted for a possible correlation between solar activity and myocardial infarction and stroke in the United States. A statistical analysis is performed using data on geomagnetic activity and the daily U.S. mortality due to coronary heart disease and stroke for the years 1962 through 1966. None of the results are found to yield any evidence of a correlation. It is concluded that correlations claimed by Soviet workers between geomagnetic activity and the incidence of various human diseases are probably not statistically significant or probably are not due to a causal relation between geomagnetic activity and disease.

  5. Initial geomagnetic field model from MAGSAT

    NASA Technical Reports Server (NTRS)

    Langel, R. A.; Estes, R. H.; Mead, G. D.; Fabiano, E. B.; Lancaster, E. R.

    1980-01-01

    Magsat data from magnetically quiet days were used to derive a thirteenth degree and order spherical harmonic geomagnetic field model, MGST(3/80). The model utilized both scalar and vector data and fit that data with standard deviations of 8, 52, 55 and 97 nT for the scalar magnitude, B sub r, B sub theta and B sub phi respectively. When compared with earlier models, the Earth's dipole moment continues to decrease at a rate of about 26 nT/year. Evaluation of earlier models with Magsat data shows that the scalar field at the Magsat epoch is best predicted by the POGO(2/72) model but that the AWC/75 and IGS/75 are better for predicting vector fields.

  6. Geomagnetic Effect Caused by 1908 Tunguska Event

    NASA Astrophysics Data System (ADS)

    Losseva, T. V.; Kuzmicheva, M. Y.

    2010-12-01

    The analysis of the magnetograms of Irkutsk observatory on the 30th June 1908 showed that the explosion of Tunguska bolide was accompanied by variations of the Earth’s magnetic field, which were being continued for several hours [1]. Irkutsk geophysical observatory is located approximately in 950 km to the southeast from the point of Tunguska explosion and it was nearest point, where the continuous recording of the components of the geomagnetic field was in progress. We suppose that it was caused by magnetic field of the current system, generated in the E-layer of ionosphere by gas dynamical flow after the Tunguska explosion [2]. Plunging through the atmosphere, cosmic body forms a hot rarefied channel behind it; the hydrostatic equilibrium of pressure in the channel becomes broken. The particles of the body vapor and atmospheric air, involved in the motion, lift along this channel upward (so-called plume). In the rarefied layers of the atmosphere they move along the ballistic trajectories in the gravitational field. While falling down gas loses its kinetic energy in dense layers of the atmosphere, which is converted into thermal energy. Then the reflected shock wave is formed. The gas heated in it rises up and all these processes repeat. The effects of heating and ionization of gas at height of 100 km, caused by the oscillations in the atmosphere, can lead to a distortion of the existing current system in ionosphere and generation of new ones. Since the Tunguska body had an oblique trajectory, the plume was ejected in the direction opposite to motion of Tunguska body and provided ionized region at the distance about 700 km from the epicenter at time moment 400 seconds after explosion. Gas dynamical simulation and estimates of the plume parameters have been fulfilled to calculate conductivity profiles and the electric field. Magnetic field of the induced current system has been obtained by the numerical simulation of Maxwell’s equations. Analysis of calculation

  7. Stochastic resonance in geomagnetic polarity reversals.

    PubMed

    Consolini, Giuseppe; De Michelis, Paola

    2003-02-07

    Among noise-induced cooperative phenomena a peculiar relevance is played by stochastic resonance. In this paper we offer evidence that geomagnetic polarity reversals may be due to a stochastic resonance process. In detail, analyzing the distribution function P(tau) of polarity residence times (chrons), we found the evidence of a stochastic synchronization process, i.e., a series of peaks in the P(tau) at T(n) approximately (2n+1)T(Omega)/2 with n=0,1,...,j and T(omega) approximately 0.1 Myr. This result is discussed in connection with both the typical time scale of Earth's orbit eccentricity variation and the recent results on the typical time scale of climatic long-term variation.

  8. Geomagnetism and paleomagnetism 1979-1983

    NASA Astrophysics Data System (ADS)

    Fuller, M.

    My function, in writing these notes, is to bring you up to date in Geomagnetism and Paleomagnetism, in as painless a manner as possible—without tears, as the French language texts for tourists used to promise. In writing this account of progress in the past quadrennium, I must first acknowledge that it is a personal and subjective viewpoint;; another reporter would surely emphasize other developments. Yet, there is some virture in writing of things, about which one knows something, so I leave to future reporters the task of redresssing the balance in matters covered.At the outset, one very sad event must be recorded. On April 3, 1981, Sir Edward Bullard died. His published work alone marks him as one of the leaders of geomagnetism in our times. Yet his contribution was much greater; many an American geophysicist, as well as a whole generation of British colleagues, have felt the benefit of his perceptive advice on their research. To those who saw him in the last few months of his life, his courage in the face of his illness was a remarkable example of fortitude. It is by now well known that the definitive paper, which he wrote with Malin, on secular variation at London, was only completed immediately before his death. The transmittal letter had been typed, but death prevented him from signing it. Bullard returned in this final paper to a topic to which he had contributed much. In it, he notes the role of Halley, who first described the phenomenon of westward drift, to which Bullard gave a new numerical precision, two and a half centuries later. I seem to remember Bullard saying in a lecture years ago that, while the Newtons of this world seem other than mortal, Halley was a scientist whose life and acheivements could encourage one's own efforts. Bullard, like Halley, inspires and encourages us.

  9. Forecasting geomagnetic activities from the Boyle Index

    NASA Astrophysics Data System (ADS)

    Bala, R.; Reiff, P. H.

    2010-12-01

    The Boyle Index (BI), Φ =10-4}( {v{2}/{km/sec) + 11.7({(B)/(nT)})sin 3}{(θ /2) kV, has been successful in predicting the geomagnetic activity since its inception in October 2003. It is available in near-real-time from http://space.rice.edu/ISTP/wind.html and provides space weather predictions of geomagnetic indices (Kp, Dst and the AE) in real time through neural network algorithms. In addition, it provides free email alerts to its 700+ subscribers whenever the magnetospheric activity levels exceed certain pre-defined thresholds. We are constantly improving our algorithms, in the interest of either including more data or improving the accuracy and lead-time of forecasts. For example, with the inclusion of two more years of data (2008 and 2009) in the training, we have the advantage of modeling one of the deepest solar minimums, which has been exceptionally low in terms of the activity level. Our algorithms have been successful in capturing the effects of ``preconditioning" and the non-linearity in the solar wind parameters (for example, see figure 1). This paper presents our new attempts to include the effects of solar turbulence by incorporating the standard deviations in the solar wind parameters along with the BI, for greater the turbulence the higher the energy input into the magnetosphere as some of the previous studies have shown. Furthermore, we will also present how 3-hour averaged 1-hour sliding window scheme have improved our predictions with lead times of 3 hours or longer. Our predictions from a recent activity, 03 August 2010.

  10. Research on Historical Records of Geomagnetic Storms

    NASA Astrophysics Data System (ADS)

    Lakhina, G. S.; Alex, S.; Tsurutani, B. T.; Gonzalez, W. D.

    In recent times, there has been keen interest in understanding Sun-Earth connection events, such as solar flares, CMEs and concomitant magnetic storms. Magnetic storms are the most dramatic and perhaps important component of space weather effects on Earth. Super-intense magnetic storms (defined here as those with Dst < -500 nT, where Dst stands for the disturbance storm time index that measures the strength of the magnetic storm) although relatively rare, have the largest societal and technological relevance. Such storms can cause life-threatening power outages, satellite damage, communication failures and navigational problems. However, the data for such magnetic storms is rather scarce. For example, only one super-intense magnetic storm has been recorded (Dst=-640 nT, March 13, 1989) during the space-age (since 1958), although such storms may have occurred many times in the last 160 years or so when the regular observatory network came into existence. Thus, research on historical geomagnetic storms can help to create a good data base for intense and super-intense magnetic storms. From the application of knowledge of interplanetary and solar causes of storms gained from the spaceage observations applied to the super-intense storm of September 1-2, 1859, it has been possible to deduce that an exceptionally fast (and intense) magnetic cloud was the interplanetary cause of this geomagnetic storm with a Dst -1760 nT, nearly 3 times as large as that of March 13, 1989 super-intense storm. The talk will focus on super-intense storms of September 1-2, 1859, and also discuss the results in the context of some recent intense storms.

  11. The geocoronal responses to the geomagnetic disturbances

    NASA Astrophysics Data System (ADS)

    Kuwabara, M.; Yoshioka, K.; Murakami, G.; Tsuchiya, F.; Kimura, T.; Yamazaki, A.; Yoshikawa, I.

    2017-01-01

    Atomic hydrogen atoms in the terrestrial exosphere resonantly scatter solar Lyman alpha (121.6 nm) radiation, observed as the hydrogen geocorona. Measurements of scattered solar photons allow us to probe time-varying distributions of exospheric hydrogen atoms. The Hisaki satellite with the extreme ultraviolet spectrometer (EXtreme ultraviolet spectrosCope for ExosphEric Dynamics: EXCEED) was launched in September 2013. EXCEED acquires spectral images (52-148 nm) of the atmospheres/magnetospheres of planets from Earth orbit. Due to its low orbital altitude ( 1000 km), the images taken by the instrument also contain the geocoronal emissions. In this context, EXCEED has provided quasi-continuous remote sensing observations of the geocorona with high temporal resolution ( 1 min) since 2013. These observations provide a unique database to determine the long-term behavior of the exospheric density structure. In this paper, we report exospheric structural responses observed by EXCEED to geomagnetic disturbances. Several geomagnetic storms with decreases of Dst index occurred in February 2014 and the Lyman alpha column brightness on the night side of the Earth increased abruptly and temporarily by approximately 10%. Hisaki reveal that the time lag between the peaks of the magnetic activity and the changes in the Lyman alpha column brightness is found to be about 2 to 6 h during storms. In order to interpret the observational results, we evaluate quantitatively the factors causing the increase. On the basis of these results, a coupling effect via charge exchange between the exosphere and plasmasphere causes variations of the exospheric density structure.

  12. 21 CFR 868.5540 - Rigid laryngoscope.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Rigid laryngoscope. 868.5540 Section 868.5540 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5540 Rigid laryngoscope. (a) Identification....

  13. Unbiased rigid registration using transfer functions

    NASA Astrophysics Data System (ADS)

    Hahn, Dieter A.; Hornegger, Joachim; Bautz, Werner; Kuwert, Torsten; Roemer, Wolfgang

    2005-04-01

    The evaluation of tumor growth as regression under therapy is an important clinical issue. Rigid registration of sequentially acquired 3D-images has proven its value for this purpose. Existing approaches to rigid image registration use the whole volume for the estimation of the rigid transform. Non-rigid soft tissue deformation, however, will imply a bias to the registration result, because local deformations cannot be modeled by rigid transforms. Anatomical substructures, like bones or teeth, are not affected by these deformations, but follow a rigid transform. This important observation is incorporated in the proposed registration algorithm. The selection of anatomical substructure is done by manual interaction of medical experts adjusting the transfer function of the volume rendering software. The parameters of the transfer function are used to identify the voxels that are considered for registration. A rigid transform is estimated by a quaternion gradient descent algorithm based on the intensity values of the specified tissue classes. Commonly used voxel intensity measures are adjusted to the modified registration algorithm. The contribution describes the mathematical framework of the proposed registration method and its implementation in a commercial software package. The experimental evaluation includes the discussion of different similarity measures, the comparison of the proposed method to established rigid registration techniques and the evaluation of the efficiency of the new method. We conclude with the discussion of potential medical applications of the proposed registration algorithm.

  14. The Personality Characteristics of the Rigid Learner.

    ERIC Educational Resources Information Center

    Dean, Raymond S.; Garabedian, A. Alexander

    1981-01-01

    Investigated personality dimensions concomitant with learner's cognitive rigidity. Results indicated the personality dimensions of tenseness, compulsivity, group dependency, absent-mindedness, sensitivity, and emotional stability explained 36 percent of the variability in subjects' increasing levels of cognitive rigidity. Showed a pervasive use of…

  15. 21 CFR 882.1020 - Rigidity analyzer.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Rigidity analyzer. 882.1020 Section 882.1020 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES NEUROLOGICAL DEVICES Neurological Diagnostic Devices § 882.1020 Rigidity analyzer....

  16. 21 CFR 882.1020 - Rigidity analyzer.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Rigidity analyzer. 882.1020 Section 882.1020 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES NEUROLOGICAL DEVICES Neurological Diagnostic Devices § 882.1020 Rigidity analyzer....

  17. 21 CFR 882.1020 - Rigidity analyzer.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Rigidity analyzer. 882.1020 Section 882.1020 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES NEUROLOGICAL DEVICES Neurological Diagnostic Devices § 882.1020 Rigidity analyzer....

  18. 21 CFR 882.1020 - Rigidity analyzer.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Rigidity analyzer. 882.1020 Section 882.1020 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES NEUROLOGICAL DEVICES Neurological Diagnostic Devices § 882.1020 Rigidity analyzer....

  19. 21 CFR 882.1020 - Rigidity analyzer.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Rigidity analyzer. 882.1020 Section 882.1020 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES NEUROLOGICAL DEVICES Neurological Diagnostic Devices § 882.1020 Rigidity analyzer....

  20. Aggregation dynamics of rigid polyelectrolytes

    NASA Astrophysics Data System (ADS)

    Tom, Anvy Moly; Rajesh, R.; Vemparala, Satyavani

    2016-01-01

    Similarly charged polyelectrolytes are known to attract each other and aggregate into bundles when the charge density of the polymers exceeds a critical value that depends on the valency of the counterions. The dynamics of aggregation of such rigid polyelectrolytes are studied using large scale molecular dynamics simulations. We find that the morphology of the aggregates depends on the value of the charge density of the polymers. For values close to the critical value, the shape of the aggregates is cylindrical with height equal to the length of a single polyelectrolyte chain. However, for larger values of charge, the linear extent of the aggregates increases as more and more polymers aggregate. In both the cases, we show that the number of aggregates decrease with time as power laws with exponents that are not numerically distinguishable from each other and are independent of charge density of the polymers, valency of the counterions, density, and length of the polyelectrolyte chain. We model the aggregation dynamics using the Smoluchowski coagulation equation with kernels determined from the molecular dynamics simulations and justify the numerically obtained value of the exponent. Our results suggest that once counterions condense, effective interactions between polyelectrolyte chains short-ranged and the aggregation of polyelectrolytes are diffusion-limited.

  1. An Impending geomagnetic transition? Hints from the past.

    NASA Astrophysics Data System (ADS)

    Laj, Carlo; Kissel, Catherine

    2015-10-01

    The rapid decrease of the geomagnetic field intensity in the last centuries has led to speculations that an attempt to a reversal or an excursion might be under way. Here we investigate this hypothesis by examining past records of geomagnetic field intensity obtained from sedimentary cores and from the study of cosmogenic nuclides. The selected records describe geomagnetic changes with an unprecedented temporal resolution between 20 and 75 kyr B.P. We find that some aspects of the present-day geomagnetic field have some similarities with those documented for the Laschamp excursion 41 kyr ago. Under the assumption that the dynamo processes for an eventual future reversal or excursion would be similar to those of the Laschamp excursion, we tentatively suggest that, whilst irreversible processes that will drive the geodynamo into a polarity change may have already started, a reversal or an excursion should not be expected before 500 to 1000 years.

  2. Interplanetary magnetic sector polarity inferred from polar geomagnetic field observations

    NASA Technical Reports Server (NTRS)

    Eriss-Christensen, E.; Lassen, K.; Wilcox, J. M.; Gonzalez, W.; Colburn, D. S.

    1971-01-01

    With the use of a prediction technique it is shown that the polarity (toward or away from the sun) of the interplanetary magnetic field can be reliably inferred from observations of the polar geomagnetic field.

  3. Human physiological reaction to geomagnetic disturbances of solar origin

    NASA Astrophysics Data System (ADS)

    Dimitrova, Sv.; Stoilova, I.

    2002-12-01

    During the last two decades publications about the influence of geomagnetic activity on human health increase but there are not still strong evidences for this relationship. We performed measurements and observations of 86 working volunteers during the period of autumn and spring equinox. We examined systolic, diastolic blood pressure and pulse rate. We also collected data for some personal health condition complaints. Four-way analyses of variance (MANOVA method) were employed and the influence of factors geomagnetic activity level, sequence of the days of measurements with respect to the increased geomagnetic activity, medicaments and sex was investigated. We also performed three-way analyses of variance and investigated influence of atmospheric pressure, medicaments and sex on the physiological parameters under consideration. Our investigations indicate that most of the persons examined irrespectively to their health status could be sensitive to the geomagnetic changes, which influence directly self-confidence and working ability.

  4. Morphological Investigation of Disturbed Ionosphere during Intense Geomagnetic Storms

    NASA Astrophysics Data System (ADS)

    Malvi, Bhupendra; Srivastav, Prateek S.; Mansoori, Azad A.; Atulkar, Roshni; Bhardwaj, Shivangi; Purohit, P. K.

    2016-10-01

    Geomagnetic Storms are the disturbed magnetic conditions, influenced and induced by Interplanetary Magnetic Field and the Charged Particle's motion around the Earth, respectively, in Geospace. As the ionosphere is woven by the earth's magnetic field it responds to the change in that. During the geomagnetic storms the filled-in plasma between the magnetic field lines, geomagnetic flux tubes, redistributes itself in effect of the magnetic field forcing. In the present study we have done the investigation of the morphology of the ionosphere over the mid and high latitude regions during intense Geomagnetic Storms. We got fairly convincing results; in three cases decrease of the critical frequency of F2 layer (foF2) and in one case enhancement of the critical frequency of F2 layer (foF2) at mid and high latitudes.

  5. A model of geomagnetic secular variation for 1980-1983

    USGS Publications Warehouse

    Peddie, N.W.; Zunde, A.K.

    1987-01-01

    We developed an updated model of the secular variation of the main geomagnetic field during 1980 through 1983 based on annual mean values for that interval from 148 worldwide magnetic observatories. The model consists of a series of 80 spherical harmonics, up to and including those of degree and order 8. We used it to form a proposal for the 1985 revision of the International Geomagnetic Reference Field (IGRF). Comparison of the new model, whose mean epoch is approximately 1982.0, with the Provisional Geomagnetic Reference Field for 1975-1980 (PGRF 1975), indicates that the moment of the centered-dipole part of the geomagnetic field is now decreasing faster than it was 5 years ago. The rate (in field units) indicated by PGRF 1975 was about -25 nT a-1, while for the new model it is -28 nT a-1. ?? 1987.

  6. Geomagnetic Variations of Near-polar Regions and Human Health

    NASA Astrophysics Data System (ADS)

    Tchistova, Z. B.; Kutinov, Y. G.

    In polar region geomagnetic variations play active role to non-linear tectonic processes. This analysis is based on spatial-time spectral representation of geomagnetic variation and wave migration transformation. Many perturbations in electromagnetic fields may because by external factors (e.g. magnetic storms, ionosphere anomalies and other phenomena related to solar activity) "trigging" tectonic processes but having no direct relation to the processes of their preparation. Geophysical processes are responsible for perturbations in Earth's rotation and orientation on wide range of time-scale, from less than a day of millions of years. The geological structure of some sites of Earth's crust promotes occurrence of wave guides a number of geophysical fields (acoustic, seismic, electromagnetic), usually of transportation of acoustic, seismic, electromagnetic energy in Earth's crust are coincide spatially. During last 250 mln years Arctic Segment has been developing as an autonomous region with circumpolar zonality of geomagnetic fields, and mass - and-energy transfer in its bowlers as well as shitting of lithospheric plates and expansion of ocean are caused by rotation forces under of expanding planet. The dynamic structure of the geomagnetic variations may be characteriz ed by the variations of the order-chaos state. The order manifest itself in the rhythmic change of the medium state. Analysis of amplitude and phase of geomagnetic variations can be information on ecological state of regions. Geomagnetic variations is intrincically a multiscale process in time and space. One of the most important features of geomagnetic variations is multicyclic character, whish predetermined both extent and character of geomagnetic show, and specific features. Recently, there are collected many facts, show dependence between the processes in the Earth's biosphere, the elements of it, gelio- geo- physical and meteorological factors. The recent experimental data gives us opportunity

  7. The Geomagnetic Field and Radiation in Near-Earth Orbits

    NASA Technical Reports Server (NTRS)

    Heirtzler, J. R.

    1999-01-01

    This report shows, in detail, how the geomagnetic field interacts with the particle flux of the radiation belts to create a hazard to spacecraft and humans in near-Earth orbit. It illustrates the geometry of the geomagnetic field lines, especially around the area where the field strength is anomalously low in the South Atlantic Ocean. It discusses how the field will probably change in the future and the consequences that may have on hazards in near space.

  8. System identification of geomagnetic disturbances initiated by the solar wind.

    NASA Astrophysics Data System (ADS)

    Zhou, Xiaoyan; Tschu, Kangkun

    1991-05-01

    On the basis of linear and time-invariant supposition, the geomagnetic disturbances initiated by the solar wind have been studied in terms of least square non-parametric identification method. The macro-external description of the response of the magnetosphere to the solar wind is given by the impulse response function. The predicted geomagnetic disturbances are compared with the observations; they are found to agree quite well.

  9. The ROSCOE Manual. Volume 15. ambient geomagnetic field

    DTIC Science & Technology

    1975-06-13

    Continue on reverse side it necessary and identify by bloc;, number) ROSCOE\\ ~ Ambient Geomagnetic Model .3 ABSTRACT fC.-ntinue on re.erse side if...necesAary end idrnttlyhr block number) A preliminary model of the ambient geomagnetic field has been adopted for use in ROSCOE. The model fits a locally...presented derivations, flow d’,%rams, Fortran listings, and a test problem and evaluation. The model is found to he both fast and accurate. ream DD I

  10. Geomagnetic disturbance and the orientation of nocturnally migrating birds.

    PubMed

    Moore, F R

    1977-05-06

    Free-flying passerine migrants respond to natural fluctuations in the earth's magnetic field. The variability in flight directions of nocturnal migrants is significantly correlated with increasing geomagnetic disturbance as measured by both the K index and various components of the earth's magnetic field. The results indicate that such disturbances influence the orientation of free-flying migrants, but the evidence is not sufficient to show that geomagnetism is a cue in their orientation system.

  11. BACT/LAER Determination Cut-off Date

    EPA Pesticide Factsheets

    This document may be of assistance in applying the New Source Review (NSR) air permitting regulations including the Prevention of Significant Deterioration (PSD) requirements. This document is part of the NSR Policy and Guidance Database. Some documents in the database are a scanned or retyped version of a paper photocopy of the original. Although we have taken considerable effort to quality assure the documents, some may contain typographical errors. Contact the office that issued the document if you need a copy of the original.

  12. A cut-off tubular geometry of loop space

    NASA Astrophysics Data System (ADS)

    Mukhopadhyay, Partha

    Motivated by the computation of loop space quantum mechanics as indicated in [14], here we seek a better understanding of the tubular geometry of loop space ℒℳ corresponding to a Riemannian manifold ℳ around the submanifold of vanishing loops. Our approach is to first compute the tubular metric of (ℳ2N+1) C around the diagonal submanifold, where (ℳN) C is the Cartesian product of N copies of ℳ with a cyclic ordering. This gives an infinite sequence of tubular metrics such that the one relevant to ℒℳ can be obtained by taking the limit N →∞. Such metrics are computed by adopting an indirect method where the general tubular expansion theorem of [21] is crucially used. We discuss how the complete reparametrization isometry of loop space arises in the large-N limit and verify that the corresponding Killing equation is satisfied to all orders in tubular expansion. These tubular metrics can alternatively be interpreted as some natural Riemannian metrics on certain bundles of tangent spaces of ℳ which, for ℳ×ℳ, is the tangent bundle Tℳ.

  13. New oral cut-off time limits in NSW.

    PubMed

    Nittis, Maria; Franco, Michele; Cochrane, Clint

    2016-11-01

    Standard collection procedure for the investigation of allegations of penile - oral assault has traditionally been the oral swab. Review of both the literature and NSW forensic laboratory results from oral swabbing has highlighted the sub-optimal nature of this method for the recovery of both sperm and offender DNA. 554 oral swabs, collected in NSW from 2010 to 2015, were analysed. Sperm detection occurred in only 4.2%. In the same period there was analysis of 104 oral rinses (of which 16.4% were positive for sperm) and 71 peri-oral samples (of which 18.3% were positive for sperm). As a result, a decision was made to revise forensic collection guidelines for sample collection in cases of penile - oral assault. Oral swabbing is no longer recommended. Current NSW forensic collection guidelines recommend the collection of both an oral rinse and a peri-oral (lip) swab. Samples are to be taken in the first 12 h after a penile - oral assault in all cases where there is a suspicion of oral assault. Oral collections may be extended to 24 h post penile - oral assault in those cases where there is either a clear recollection of ejaculation into the mouth (or ejaculation elsewhere prior to penile penetration of the mouth) or in those cases where a complainant is clear that there had been penile penetration of the mouth but is unable to recall whether or not ejaculation has taken place.

  14. Characteristics Of Fused Couplers Below Cut-Off

    NASA Astrophysics Data System (ADS)

    Meyer, T. J.; Tekippe, V. J.

    1989-02-01

    A number of different architectures are being explored for the utilization of optical fiber in the subscriber loop. In addition to reliability and maintainability, cost is a prime consideration since full implementation of fiber in the local loop will not occur until it is economically viable. It is becoming increasingly clear that in order to accommodate a number of ISDN applications, including high definition television (HDTV), singlemode fiber with a singlemode laser at the terminal end will be required. The situation at the subscriber end is quite different, however. The data rates are expected to be low on the return path to allow for POTS ( plain old telephone service) and some data transfer. When this requirement is combined with cost and reliability considerations, the inexpensive lasers developed for the CD (compact disk) market become quite attractive. The biggest disadvantage of this source is that the fiber which is optimized for singlemode operation at 1300nm tends to be multimode in the 800nm band where these lasers operate. Previous papers have considered such effects as modal noise and pulse dispersion when using these lasers with fiber that is singlemode in the 1300nm band.[1] Another consideration is the passive components required to implement such an architecture. Figure 1 shows a typical bidirectional design with full duplex operation on a single fiber. The key component is the 800/1300 wavelength division multiplexer/demultiplexer (WDM). Because of the multimode nature of the fiber in the 800nm band, all fiber approaches to fabricating the WDM, such as the fused beconical taper (FBT) approach, raise new issues which are not encountered, for example, with 1300/1500nm WDM's.[2] In this paper we discuss the effects of the multimode behavior of the fiber on the performance of fused couplers and WDM's.

  15. [ANTHROPOMETRIC PARAMETERS' CUT-OFF POINTS FOR DIAGNOSIS OF SARCOPENIA].

    PubMed

    Canda Moreno, Alicia S

    2015-08-01

    Introducción: la sarcopenia es un síndrome caracterizado por baja masa muscular junto con pérdida de fuerza y/o disminución del rendimiento físico. Debido al envejecimiento de nuestra población, se ha producido un aumento de su prevalencia relacionada con la edad, a la que se suman otros factores causados por ciertas enfermedades o la malnutrición. Objetivo: ofrecer una herramienta para el diagnóstico de sarcopenia que determine de forma accesible la pérdida de masa muscular. Material y métodos: se realizó un protocolo antropométrico estandarizado en 883 varones y 506 mujeres, sanos y activos, de edad entre 20 y 39 años. Se calcularon los siguientes índices de desarrollo muscular: perímetros (brazo, antebrazo, muslo y pierna), perímetros corregidos (brazo, muslo y pierna), áreas musculares transversales (CSA de brazo, muslo y pierna) y masa muscular total (kg), en porcentaje (%) y relativa a la talla (kg/m2) mediante la ecuación de Lee. Se fijó como punto de corte el percentil 2,5 (rango inferior del 95% del intervalo de confianza) para las variables estudiadas. Resultados: se encontraron diferencias significativas (p < 0,0001) entre varones y mujeres en todos los indicadores. Los valores del punto de corte de diagnóstico de baja masa muscular fue en varones de 9,1 kg/m2, y en mujeres de 7,3 kg/m2. Y para las CSA (cm2) varón vs. mujer: brazo, 37,7 vs. 24,2; muslo, 154,3 vs. 115,8; y pierna, 78,8 vs. 60,2. Conclusiones: existe dimorfismo sexual que exige criterios diagnósticos diferenciados. La técnica antropométrica puede servir como screening de sarcopenia en el estudio de grandes poblaciones.

  16. Influence of geomagnetic activity and atmospheric pressure in hypertensive adults.

    PubMed

    Azcárate, T; Mendoza, B

    2017-03-30

    We performed a study of the systolic and diastolic arterial blood pressure behavior under natural variables such as the atmospheric pressure and the horizontal geomagnetic field component. We worked with a group of eight adult hypertensive volunteers, four men and four women, with ages between 18 and 27 years in Mexico City during a geomagnetic storm in 2014. The data was divided by gender, age, and day/night cycle. We studied the time series using three methods: correlations, bivariate analysis, and superposed epoch (within a window of 2 days around the day of occurrence of a geomagnetic storm) analysis, between the systolic and diastolic blood pressure and the natural variables. The correlation analysis indicated a correlation between the systolic and diastolic blood pressure and the atmospheric pressure and the horizontal geomagnetic field component, being the largest during the night. Furthermore, the correlation and bivariate analyses showed that the largest correlations are between the systolic and diastolic blood pressure and the horizontal geomagnetic field component. Finally, the superposed epoch analysis showed that the largest number of significant changes in the blood pressure under the influence of geomagnetic field occurred in the systolic blood pressure for men.

  17. Are migrating raptors guided by a geomagnetic compass?

    USGS Publications Warehouse

    Thorup, Kasper; Fuller, Mark R.; Alerstam, T.; Hake, M.; Kjellen, N.; Standberg, R.

    2006-01-01

    We tested whether routes of raptors migrating over areas with homogeneous topography follow constant geomagnetic courses more or less closely than constant geographical courses. We analysed the routes taken over land of 45 individual raptors tracked by satellite-based radiotelemetry: 25 peregrine falcons, Falco peregrinus, on autumn migration between North and South America, and seven honey buzzards, Pernis apivorus, and 13 ospreys, Pandion haliaetus, on autumn migration between Europe and Africa. Overall, migration directions showed a better agreement with constant geographical than constant geomagnetic courses. Tracks deviated significantly from constant geomagnetic courses, but were not significantly different from geographical courses. After we removed movements directed far from the mean direction, which may not be migratory movements, migration directions still showed a better agreement with constant geographical than constant geomagnetic courses, but the directions of honey buzzards and ospreys were not significantly different from constant geomagnetic courses either. That migration routes of raptors followed by satellite telemetry are in closer accordance with constant geographical compass courses than with constant geomagnetic compass courses may indicate that geographical (e.g. based on celestial cues) rather than magnetic compass mechanisms are of dominating importance for the birds' long-distance orientation.

  18. Local geomagnetic indices and their role in space weather

    NASA Astrophysics Data System (ADS)

    Guerrero, Antonio; Cid, Consuelo; Saiz, Elena; Palacios, Judith; Cerrato, Yolanda

    2016-04-01

    The analysis of local geomagnetic disturbances (specific longitude and latitude) have recently proved to play an important role in space weather research. Localized strong (high intensity) and impulsive (fast developed and fast recovered) geomagnetic disturbances are typically recorded at high latitudes and commonly related to field-aligned currents. These type of disturbances are also recorded, less frequently, at mid and low latitudes, representing an important hazard for technology. In order to obtain geomagnetic disturbances (geomagnetic index) from the records at a certain observatory, a baseline has to be removed. The baseline is usually determined taking into account geomagnetic secular variation and solar quiet time. At mid-latitudes the shape of the daily solar quiet component presents a strong day-to-day variability difficult to predict. In this work we present a new technique capable to determine the baseline at mid-latitudes which allows us to obtain a high resolution local geomagnetic index with the highest accuracy ever obtained at mid-latitudes.

  19. Globally strong geomagnetic field intensity circa 3000 years ago

    NASA Astrophysics Data System (ADS)

    Hong, Hoabin; Yu, Yongjae; Lee, Chan Hee; Kim, Ran Hee; Park, Jingyu; Doh, Seong-Jae; Kim, Wonnyon; Sung, Hyongmi

    2013-12-01

    High-fidelity geomagnetic field intensity determination was carried out using 191 baked fragments collected from 20 kilns or hearths with ages ranging between ∼1200 BC and ∼AD 1725 in South Korea. Geomagnetic field intensity variation displayed three narrow minima at ∼800-700 BC, ∼AD 700, and ∼AD 1600 and two maxima at ∼1200-1100 BC and ∼AD 1000-1100. In most time intervals, virtual axial dipole moment (VADM) variation is confined within 20% of the present VADM. However, geomagnetic field intensity circa 3000 yr ago is nearly 40% larger than the present value. Such high VADMs circa 3000 yr ago are in phase with those in other longitudinal bands in northern hemisphere centered at 5E (France), 30E (the Middle East) and 200E (Hawaii). Although strong geomagnetic field intensity circa 3000 yr ago is globally synchronous, the highest VADM occurs at slightly different time intervals in different locations. Hence it is possible that the globally strong geomagnetic field intensity circa 3000 yr ago reflects the migration of persistent hemispheric flux in northern hemisphere or an episode of geomagnetic field hemispheric asymmetry.

  20. Multifractal analysis of low-latitude geomagnetic fluctuations

    NASA Astrophysics Data System (ADS)

    Bolzan, M. J. A.; Rosa, R. R.; Sahai, Y.

    2009-02-01

    The technique of large deviation multifractal spectrum has shown that the high-latitude (77.5° N, 69.2° W) geomagnetic fluctuations can be described from direct dissipation process or loading-unloading regimes of the solar wind-magnetosphere coupling. In this paper, we analyze the H-component of low-latitude (22.4° S, 43.6° W) geomagnetic field variability observed during the month of July 2000 at the Geomagnetic Observatory, Vassouras, RJ, Brazil. The variability pattern during this period is a mixture of quiet and disturbed days including the Bastille Day intense geomagnetic storm on 15 July. Due to the complexity of this data, we pursue a detailed analysis of the geomagnetic fluctuations in different time scales including a multifractal approach using the singular power spectrum deviations obtained from the wavelet transform modulus maxima (WTMM). The results suggest, as observed from high-latitude data, the occurrence of low-latitude multifractal processes driving the intermittent coupling between the solar wind-magnetosphere and geomagnetic field variations. On finer scales possible physical mechanisms in the context of nonlinear magnetosphere response are discussed.

  1. A Quaternary Geomagnetic Instability Time Scale

    NASA Astrophysics Data System (ADS)

    Singer, B. S.

    2013-12-01

    Reversals and excursions of Earth's geomagnetic field create marker horizons that are readily detected in sedimentary and volcanic rocks worldwide. An accurate and precise chronology of these geomagnetic field instabilities is fundamental to understanding several aspects of Quaternary climate, dynamo processes, and surface processes. For example, stratigraphic correlation between marine sediment and polar ice records of climate change across the cryospheres benefits from a highly resolved record of reversals and excursions. The temporal patterns of dynamo behavior may reflect physical interactions between the molten outer core and the solid inner core or lowermost mantle. These interactions may control reversal frequency and shape the weak magnetic fields that arise during successive dynamo instabilities. Moreover, weakening of the axial dipole during reversals and excursions enhances the production of cosmogenic isotopes that are used in sediment and ice core stratigraphy and surface exposure dating. The Geomagnetic Instability Time Scale (GITS) is based on the direct dating of transitional polarity states recorded by lava flows using the 40Ar/39Ar method, in parallel with astrochronologic age models of marine sediments in which O isotope and magnetic records have been obtained. A review of data from Quaternary lava flows and sediments yields a GITS comprising 10 polarity reversals and 27 excursions during the past 2.6 million years. Nine of the ten reversals bounding chrons and subchrons are associated with 40Ar/39Ar ages of transitionally-magnetized lava flows. The tenth, the Guass-Matuyama chron boundary, is tightly bracketed by 40Ar/39Ar dated ash deposits. Of the 27 well-documented excursions, 14 occurred during the Matuyama chron and 13 during the Brunhes chron; 19 have been dated directly using the 40Ar/39Ar method on transitionally-magnetized volcanic rocks and form the backbone of the GITS. Excursions are clearly not the rare phenomena once thought

  2. Geomagnetic Field -- From Paleomagnetism to Dynamo Theory

    NASA Astrophysics Data System (ADS)

    Kono, M.

    2008-05-01

    Since 1995, self-consistent models of the geodynamo became available. There are certain problems, but some of these models have shown behaviors quite similar to those observed by paleomagnetism, including polarity reversals (Kono and Roberts, 2002). There is thus a hope that the combination of paleomagnetism and dynamo theory may provide us a very comprehensive understanding of the geomagnetic field. In this paper, I will try to highlight the possibilities and limitations in such studies. From satellite observations, it was shown that the power of the magnetic field contained in each degree is nearly the same if measured at the core-mantle boundary (CMB). The core field can be seen only to degree 13 or 14 where the field power is about (10 nT)2. Beyond that, the crustal magnetization dominates and the core signal is lost. The value of 10 nT is far larger than the accuracy of the present-day instruments, but much smaller than the resolution obtainable by paleomagnetic observations. We may safely assume that the error in paleomagnetic measurements (in direction) is of the order of 10 degrees. This error corresponds to the resolution of about 1/5. The relative powers of the low degree terms in the magnetic field at the surface are 1.0, 0.033, 0.019, 0.0055 (Langel and Estes, 1982). This means that only the degrees 1 to 3 terms may be distinguished by paleomagnetic data. From the combination of dipole, quadrupole, and octupole, what we can deduce about the fundamental properties of the geomagnetic field? Here are some of the possibilities, which may give important clues when we compare with dynamo simulation results. (1) The current dipole power is several times larger than the value expected from the trend line produced by degrees 2--13. Is this a persistent feature or transient? (2) In PSV analysis, the angular standard deviation increases with latitude. Kono and Tanaka (1995) showed that it is possible only if the (2,1) (degree, order) or (3,2) term is very large

  3. Secular variation of the middle and late Miocene geomagnetic field recorded by the Columbia River Basalt Group in Oregon, Idaho and Washington, USA

    NASA Astrophysics Data System (ADS)

    Dominguez, Ada R.; Van der Voo, Rob

    2014-06-01

    This study of 118 discrete volcanic flows from the Columbia River Basalt Group is aimed to determine their distribution of geomagnetic field directions and virtual geomagnetic poles (VGPs) and to compare the inherent secular variation parameters with those from other studies. The magnetic signature of these rocks is uniformly carried by primary titanomagnetite, indicating that magnetic changes are due to variations in the magnetic field. Although most flows are flat lying, those that are tilted pass the Tauxe and Watson tilt test. Sequential flows with statistically similar site means were grouped, and directions that were considered outliers were evaluated and removed using the Vandamme cut-off method. Three normal-polarity (N-polarity) and three reversed-polarity (R-polarity) intervals are revealed by the stratigraphically ordered flows and have mean directions of N polarity (dec/inc = 6.6°/+61.2°, k = 29.3, α95 = 4.2°), and R polarity (dec/inc = 178.2°/-59.2°, k = 16, α95 = 5.5°). Regression analysis indicates that the secular variation analysis has not been affected by regional rotation, and that apparent polar wander is negligible. The VGP distribution is almost perfectly circular and supports the preference of VGP positions for the dispersion analysis. Dispersion parameters with corrections for within-site scatter (Sb) show a range of 14.3°-25.5°, including error limits, and were consistently higher for R-polarity results than for those of N polarity. Published dispersion parameters for extrusives <5 Ma show Sb values slightly lower than ours, yielding values of 16°-19°, although the difference is not statistically significant. In contrast, published dispersion parameters from high quality data from the Cretaceous Normal Superchron are lower than those for the Neogene, which suggests that the noisiness of the magnetic field correlates with the frequency of reversals. Our new results allow us to extend the Plio-Pleistocene palaeosecular variation

  4. Periodic substorm activity in the geomagnetic tail

    NASA Technical Reports Server (NTRS)

    Huang, C. Y.; Eastman, T. E.; Frank, L. A.; Williams, D. J.

    1983-01-01

    On 19 May 1978 an anusual series of events is observed with the Quadrispherical LEPEDEA on board the ISEE-1 satellite in the Earth's geomagnetic tail. For 13 hours periodic bursts of both ions and electrons are seen in all the particle detectors on the spacecraft. On this day periodic activity is also seen on the ground, where multiple intensifications of the electrojets are observed. At the same time the latitudinal component of the interplanetary magnetic field shows a number of strong southward deflections. It is concluded that an extended period of substorm activity is occurring, which causes repeated thinnings and recoveries of the plasma sheet. These are detected by ISEE, which is situated in the plasma sheet boundary layer, as periodic dropouts and reappearances of the plasma. Comparisons of the observations at ISEE with those at IMP-8, which for a time is engulfed by the plasma sheet, indicate that the activity is relatively localized in spatial extent. For this series of events it is clear that a global approach to magnetospheric dynamics, e.g., reconnection, is inappropriate.

  5. Geomagnetism during solar cycle 23: Characteristics.

    PubMed

    Zerbo, Jean-Louis; Amory-Mazaudier, Christine; Ouattara, Frédéric

    2013-05-01

    On the basis of more than 48 years of morphological analysis of yearly and monthly values of the sunspot number, the aa index, the solar wind speed and interplanetary magnetic field, we point out the particularities of geomagnetic activity during the period 1996-2009. We especially investigate the last cycle 23 and the long minimum which followed it. During this period, the lowest values of the yearly averaged IMF (3 nT) and yearly averaged solar wind speed (364 km/s) are recorded in 1996, and 2009 respectively. The year 2003 shows itself particular by recording the highest value of the averaged solar wind (568 km/s), associated to the highest value of the yearly averaged aa index (37 nT). We also find that observations during the year 2003 seem to be related to several coronal holes which are known to generate high-speed wind stream. From the long time (more than one century) study of solar variability, the present period is similar to the beginning of twentieth century. We especially present the morphological features of solar cycle 23 which is followed by a deep solar minimum.

  6. The Livingston Island Geomagnetic and Ionospheric Observatory

    NASA Astrophysics Data System (ADS)

    Altadill, David; Marsal, Santiago; Blanch, Estefania; Miquel Torta, J.; Quintana-Seguí, Pere; Germán Solé, J.; Cid, Òscar; José Curto, Juan; Ibáñez, Miguel; Segarra, Antoni; Lluís Pijoan, Joan; Juan, Juan Miguel

    2014-05-01

    The Ebre Observatory Institute manages a geophysical observatory installed at the Spanish Antarctic Station (SAS) Juan Carlos I. It was set up in 1995 and it has been updated yearly by our team throughout several projects carried out since then. Nowadays, it hosts a magnetic station providing 1-second data of the 3 components (X, Y, Z) and the total force (F) during the entire year, and an ionospheric station providing vertical and oblique data during austral summer. This observatory has provided long data series of high scientific value from this remote region of the Earth. They have been used to improve the knowledge of the climate and weather behavior of the geomagnetic field and ionosphere in the area, and to model and expand the capacity of data transmission. This contribution aims to present a brief review of the instruments installed at SAS, the research results obtained from their data, and the developing activities under the current project. Finally, future perspectives are outlined with regard to adapting our geophysical observatory to the evolving needs of observatory practice.

  7. Historical Data for Geomagnetic Field Modelling

    NASA Technical Reports Server (NTRS)

    Jackson, Andrew

    1992-01-01

    Described here are the various types of historical data (by which we mean actual measurements of the field taken in the past) which are available for geomagnetic field modelling, concentrating exclusively on observations made prior to the 20th century. These data take quite diverse forms, being derived from voyages of discovery or scientific expeditions, from surveys on land, or from observatories after the formation of the Gottingen Magnetic Union. Toward the latter part of the 19th Century, declination was measured quite regularly by various naval vessels for the purpose of constructing charts. Prior to the invention of a method for measuring field intensities by Gauss in 1832, all measurements were of declination or inclination. During the 19th Century over 40,000 observations are available in one year (the first International Polar Year 1882-83). Prior to 1800 there are only of the order of 12,000 measurements. We discuss measurement methods and the types of instruments used, and focus on specific problems which have been noted, such as those associated with the measurement of intensity on iron ships in the late 19th Century.

  8. Geomagnetism during solar cycle 23: Characteristics

    PubMed Central

    Zerbo, Jean-Louis; Amory-Mazaudier, Christine; Ouattara, Frédéric

    2012-01-01

    On the basis of more than 48 years of morphological analysis of yearly and monthly values of the sunspot number, the aa index, the solar wind speed and interplanetary magnetic field, we point out the particularities of geomagnetic activity during the period 1996–2009. We especially investigate the last cycle 23 and the long minimum which followed it. During this period, the lowest values of the yearly averaged IMF (3 nT) and yearly averaged solar wind speed (364 km/s) are recorded in 1996, and 2009 respectively. The year 2003 shows itself particular by recording the highest value of the averaged solar wind (568 km/s), associated to the highest value of the yearly averaged aa index (37 nT). We also find that observations during the year 2003 seem to be related to several coronal holes which are known to generate high-speed wind stream. From the long time (more than one century) study of solar variability, the present period is similar to the beginning of twentieth century. We especially present the morphological features of solar cycle 23 which is followed by a deep solar minimum. PMID:25685427

  9. Major Geomagnetic Storms in Solar Cycle 24

    NASA Astrophysics Data System (ADS)

    Zheng, Y.

    2013-12-01

    Solar Cycle 24 has produced 11 major geomagnetic storms (where Dstmin < -100 nT) with three in 2011, six in 2012 and two in 2013 (as of 7 August 2013). Detailed analysis of each event will be given in terms of its solar driver(s): CME, coronal hole high speed solar wind stream (HSS), multiple CMEs or interactions between CME and HSS. While some of these storms are associated with a fast and wide CME, the few cases involving slow or common CMEs and interactions with HSS are particularly interesting. These events pose great challenges for accurate space weather forecasting, since operationally the slower or average CMEs tend to receive less attention and are sometimes overlooked altogether. The characteristics of such challenging, not-so-fast yet geoeffective CME events (such as their coronal signatures and interactions with surrounding solar wind structure(s), etc) will be examined in detail, with the goal of extracting common and telltale features, if any, of these CMEs that distinguish them from CMEs in a similar category.

  10. Low-dimensional analysis of geomagnetic reversals

    NASA Astrophysics Data System (ADS)

    Morzfeld, M.; Fournier, A.; Hulot, G.

    2015-12-01

    Low-dimensional models for Earth's magnetic dipole have attracted attention recently because they may be a powerful tool to study the dominant dynamics over geological time-scales, where direct numerical simulation remains challenging. We investigate the extent to which several low-dimensional models can explain the Earth's dipole dynamics by comparing them to the signed relative paleointensity over the past 2 million years. Our comparisons of models and data are done by Bayesian statistics, which allows us to incorporate nonlinearity and uncertainty into the computations. The comparison, or data assimilation, reveals the strengths and weaknesses of each low-dimensional model and suggests improvements to the low-dimensional models. We also investigate if low-dimensional models can predict dipole reversals by performing extensive numerical experiments, and by hind-casting the Laschamp event, the Bruhnes-Matuyama reversal, as well as four other reversals documented over the past two million years. Our analysis stresses the need for models of geomagnetic reversals to faithfully account for the full spectrum of variability of paleomagnetic intensity.

  11. History of the Munich-Maisach-Fürstenfeldbruck Geomagnetic Observatory

    NASA Astrophysics Data System (ADS)

    Soffel, H. C.

    2015-07-01

    The Munich-Maisach-Fürstenfeldbruck Geomagnetic Observatory is one of the observatories with the longest recordings of the geomagnetic field. It started with hourly measurements on 1 August 1840. The founder of the observatory in Munich was Johann von Lamont (1805-1879), the Director of the Royal Bavarian Astronomical Observatory. He had been stimulated to build his own observatory by the initiative of the Göttingen Magnetic Union founded in 1834 by Alexander von Humboldt (1769-1859) and Carl Friedrich Gauss (1777-1855). Before 1840 fewer than five observatories existed; the most prominent ones were those in London and Paris. At the beginning Lamont used equipment delivered by Gauss in Göttingen, but soon started to build instruments of his own design. Among them was a nonmagnetic theodolite which allowed precise geomagnetic measurements to be made also in the field. During the 1850s Lamont carried out geomagnetic surveys and produced geomagnetic maps for Germany and many other European countries. At the end of the nineteenth century accurate geomagnetic measurements in Munich became more and more disturbed by the magnetic stray fields from electric tramways and industry. During this period the quality of the data suffered and the measurements had to be interrupted several times. After a provisional solution in Maisach, a village 25 km west of Munich, a final solution could be found in the vicinity of the nearby city of Fürstenfeldbruck. Here the measurements started again on 1 January 1939. Since the 1980s the observatory has been part of INTERMAGNET, an organization providing almost real-time geomagnetic data of the highest quality.

  12. Some pathophysiological aspects of the parkinsonian rigidity.

    PubMed

    Delwaide, P J; Sabbatino, M; Delwaide, C

    1986-01-01

    The neurophysiological mechanisms explaining parkinsonian rigidity are still poorly understood. Its reflex nature is well established but the peripheral afferents causing it are likely multiple and not restricted to IA afferents. Few modifications appear in spinal cord reflex mechanisms and are limited to some interneurones (reciprocal inhibition and flexor reflex). At present, the most plausible explanation of rigidity relies on hyperactivity in long loop reflex pathways relaying in the brain.

  13. Langevin thermostat for rigid body dynamics.

    PubMed

    Davidchack, Ruslan L; Handel, Richard; Tretyakov, M V

    2009-06-21

    We present a new method for isothermal rigid body simulations using the quaternion representation and Langevin dynamics. It can be combined with the traditional Langevin or gradient (Brownian) dynamics for the translational degrees of freedom to correctly sample the canonical distribution in a simulation of rigid molecules. We propose simple, quasisymplectic second-order numerical integrators and test their performance on the TIP4P model of water. We also investigate the optimal choice of thermostat parameters.

  14. A study of geomagnetic field variations along the 80° S geomagnetic parallel

    NASA Astrophysics Data System (ADS)

    Lepidi, Stefania; Cafarella, Lili; Francia, Patrizia; Piancatelli, Andrea; Pietrolungo, Manuela; Santarelli, Lucia; Urbini, Stefano

    2017-01-01

    The availability of measurements of the geomagnetic field variations in Antarctica at three sites along the 80° S geomagnetic parallel, separated by approximately 1 h in magnetic local time, allows us to study the longitudinal dependence of the observed variations. In particular, using 1 min data from Mario Zucchelli Station, Scott Base and Talos Dome, a temporary installation during 2007-2008 Antarctic campaign, we investigated the diurnal variation and the low-frequency fluctuations (approximately in the Pc5 range, ˜ 1-7 mHz). We found that the daily variation is clearly ordered by local time, suggesting a predominant effect of the polar extension of midlatitude ionospheric currents. On the other hand, the pulsation power is dependent on magnetic local time maximizing around magnetic local noon, when the stations are closer to the polar cusp, while the highest coherence between pairs of stations is observed in the magnetic local nighttime sector. The wave propagation direction observed during selected events, one around local magnetic noon and the other around local magnetic midnight, is consistent with a solar-wind-driven source in the daytime and with substorm-associated processes in the nighttime.

  15. Rigid shells enhance survival of gekkotan eggs.

    PubMed

    Andrews, Robin M

    2015-11-01

    The majority of lizards and snakes produce permeable parchment-shelled eggs that require high moisture conditions for successful embryonic development. One clade of gekkotan lizards is an exception; females produce relatively impermeable rigid-shelled eggs that normally incubate successfully under low moisture conditions. I tested the hypothesis that the rigid-shell increases egg survival during incubation, but only under low moisture conditions. To test this hypothesis, I incubated rigid-shelled eggs of Chondrodactylus turneri under low and under high moisture conditions. Eggs were incubated with parchment-shelled eggs of Eublepharis macularius to insure that incubation conditions were suitable for parchment-shelled eggs. Chondrodactylus turneri eggs had very high survival (>90%) when they were incubated under low moisture conditions. In contrast, eggs incubated under high moisture conditions had low survival overall, and lower survival than those of the parchment-shelled eggs of E. macularius. Mortality of C. turneri and E. macularius eggs incubated under high moisture conditions was the result of fungal infection, a common source of egg mortality for squamates under laboratory and field conditions. These observations document high survival of rigid-shelled eggs under low moisture conditions because eggs escape from fungal infection. Highly mineralized rigid shells also make egg survival independent of moisture availability and may also provide protection from small invertebrates in nature. Enhanced egg survival could thus compensate for the low reproductive output of gekkotans that produce rigid-shelled eggs.

  16. Historically Large Geomagnetic Storms and Potential Electric Power Grid Impacts

    NASA Astrophysics Data System (ADS)

    Kappenman, J. G.

    2004-05-01

    While recent work has been done to examine the possible Dst Intensity of historically large geomagnetic storms, the impacts caused to modern day electric power grids from these storms occurs due to rapid rate-of-change of regional geomagnetic fields which in most cases are driven by large ionospheric electrojet current intensifications. These temporally and spatially dynamic disturbance morphologies are not well-characterized by Dst or other broad geomagnetic storm indices. For estimates of storm intensity that correctly scale the threat potential to electric power grids, it is necessary to describe the rate-of-change of geomagnetic field. The rate-of-change of the geomagnetic field (dB/dt usually measured in nT/min) creates at ground level a geoelectric field that causes the flow of geomagnetically-induced currents (GIC) through ground connection points in electric power grids. Therefore in general, the larger the dB/dt, the larger the resulting geo-electric field and GIC in exposed power grid infrastructures and the greater the operational impact these induced currents will have on the power grid. Both extensive modeling analysis and recent operational experience suggests that power grids are becoming more vulnerable to geomagnetic storms as they grow in size and complexity. Also, large power grid blackouts have occurred at relatively low geomagnetic storm intensities. For example, the regional disturbance intensity that triggered the Hydro Quebec collapse during the March 13, 1989 Superstorm only reached an intensity of 479 nT/min. Large numbers of power system impacts in the United States were also observed for intensities that ranged from 300 to 600 nT/min during this storm. Yet both recent and historical data indicate that storms with disturbance levels that range from 2000 nT/min to as much ~5000 nT/min may be possible over extensive regions at latitudes of concern for large continental power grids across North America and Europe. Large GIC have also been

  17. Intensity of the geomagnetic field in Europe for the last 3 ka: Influence of data quality on geomagnetic field modeling

    NASA Astrophysics Data System (ADS)

    Pavón-Carrasco, Francisco Javier; Gómez-Paccard, Miriam; Hervé, Gwenaël.; Osete, María. Luisa; Chauvin, Annick

    2014-06-01

    of the main challenges of paleomagnetic research is to obtain high-resolution geomagnetic field intensity reconstructions. For the last millennia, these reconstructions are mostly based on archeomagnetic data. However, the quality of the intensity data available in the databases is very variable, and the high scatter observed in the records clearly suggests that some of them might not be reliable. In this work we investigate how the geomagnetic field intensity reconstructions and, hence, our present knowledge of the geomagnetic field in the past, are affected by the quality of the data selected for modeling the Earth's magnetic field. For this purpose we rank the European archeointensity data in four quality categories following widely accepted paleomagnetic criteria based on the methodology used during the laboratory treatment of the samples and on the number of specimens retained to calculate the mean intensities. Four geomagnetic field regional models have been implemented by applying the revised spherical cap harmonic analysis to these four groups of input data. Geomagnetic field models strongly depend on the used data set. The model built using all the available data (without any preselection) appears to be the less accurate, indicating some internal inconsistencies of the data set. In addition, some features of this model are clearly dominated by the less reliable archeointensity data, suggesting that such features might not reflect real variations of the past geomagnetic field. On the contrary, the regional model built on selected high-quality intensity data shows a very consistent intensity pattern at the European scale, confirming that the main intensity changes observed in Europe in the recent history of the geomagnetic field occurred at the continental scale.

  18. Wavelet-based multiscale analysis of geomagnetic disturbance

    NASA Astrophysics Data System (ADS)

    Zaourar, N.; Hamoudi, M.; Mandea, M.; Balasis, G.; Holschneider, M.

    2013-12-01

    The dynamics of external contributions to the geomagnetic field is investigated by applying time-frequency methods to magnetic observatory data. Fractal models and multiscale analysis enable obtaining maximum quantitative information related to the short-term dynamics of the geomagnetic field activity. The stochastic properties of the horizontal component of the transient external field are determined by searching for scaling laws in the power spectra. The spectrum fits a power law with a scaling exponent β, a typical characteristic of self-affine time-series. Local variations in the power-law exponent are investigated by applying wavelet analysis to the same time-series. These analyses highlight the self-affine properties of geomagnetic perturbations and their persistence. Moreover, they show that the main phases of sudden storm disturbances are uniquely characterized by a scaling exponent varying between 1 and 3, possibly related to the energy contained in the external field. These new findings suggest the existence of a long-range dependence, the scaling exponent being an efficient indicator of geomagnetic activity and singularity detection. These results show that by using magnetogram regularity to reflect the magnetosphere activity, a theoretical analysis of the external geomagnetic field based on local power-law exponents is possible.

  19. Improving geomagnetic observatory data in the South Atlantic Anomaly

    NASA Astrophysics Data System (ADS)

    Matzka, Jürgen; Morschhauser, Achim; Brando Soares, Gabriel; Pinheiro, Katia

    2016-04-01

    The Swarm mission clearly proofs the benefit of coordinated geomagnetic measurements from a well-tailored constellation in order to recover as good as possible the contributions of the various geomagnetic field sources. A similar truth applies to geomagnetic observatories. Their scientific value can be maximised by properly arranging the position of individual observatories with respect to the geometry of the external current systems in the ionosphere and magnetosphere, with respect to regions of particular interest for secular variation, and with respect to regions of anomalous electric conductivity in the ground. Here, we report on our plans and recent efforts to upgrade geomagnetic observatories and to recover unpublished data from geomagnetic observatories at low latitudes in the South Atlantic Anomaly. In particular, we target the magnetic equator with the equatorial electrojet and low latitudes to characterise the Sq- and ring current. The observatory network that we present allows also to study the longitudinal structure of these external current systems. The South Atlantic Anomaly region is very interesting due to its secular variation. We will show newly recovered data and comparisons with existing data sets. On the technical side, we introduce low-power data loggers. In addition, we use mobile phone data transfer, which is rapidly evolving in the region and allows timely data access and quality control at remote sites that previously were not connected to the internet.

  20. Secular trends in storm-level geomagnetic activity

    USGS Publications Warehouse

    Love, J.J.

    2011-01-01

    Analysis is made of K-index data from groups of ground-based geomagnetic observatories in Germany, Britain, and Australia, 1868.0-2009.0, solar cycles 11-23. Methods include nonparametric measures of trends and statistical significance used by the hydrological and climatological research communities. Among the three observatory groups, German K data systematically record the highest disturbance levels, followed by the British and, then, the Australian data. Signals consistently seen in K data from all three observatory groups can be reasonably interpreted as physically meaninginful: (1) geomagnetic activity has generally increased over the past 141 years. However, the detailed secular evolution of geomagnetic activity is not well characterized by either a linear trend nor, even, a monotonic trend. Therefore, simple, phenomenological extrapolations of past trends in solar and geomagnetic activity levels are unlikely to be useful for making quantitative predictions of future trends lasting longer than a solar cycle or so. (2) The well-known tendency for magnetic storms to occur during the declining phase of a sunspot-solar cycles is clearly seen for cycles 14-23; it is not, however, clearly seen for cycles 11-13. Therefore, in addition to an increase in geomagnetic activity, the nature of solar-terrestrial interaction has also apparently changed over the past 141 years. ?? Author(s) 2011.

  1. Metrology of Non-Rigid Objects

    SciTech Connect

    Blaedel, K L; Smith, D W; Claudet, A A; Kasper, E P; Patterson, S R

    2002-01-01

    Dimensional characterization of non-rigid parts presents many challenges. For example, when a non-rigid part is mounted in an inspection apparatus the effects of fixturing constraints cause significant deformation of the part. If the part is not used in normal service with the same load conditions as during inspection, the dimensional characteristics in service will deviate from the reported values during inspection. Further, the solution of designing specialized fixturing to duplicate ''as-installed'' conditions does not fully resolve the problem because each inspection requires its own methodology. The goal of this project is to formulate the research problem and propose a method of assessing the dimensional characteristics of non-rigid parts. The measured dimension of a rigid component is traceable at some level of confidence to a single source (NIST in the USA). Hence the measurement of one component of an assembly can be related to the measurement of another component of that assembly. There is no generalized analog to this pedigreed process for dimensionally characterizing non-rigid bodies. For example, a measurement made on a sheet-metal automobile fender is heavily influenced by how it is held during the measurement making it difficult to determine how well that fender will assemble to the rest of the (non-rigid) car body. This problem is often overcome for specific manufacturing problems by constructing rigid fixtures that over-constrain the non-rigid parts to be assembled and then performing the dimensional measurement of the contour of each component to check whether each meets specification. Note that such inspection measurements will yield only an approximation to the assembled shape, which is a function of both the geometry and the compliance of the component parts of the assembly. As a result, non-rigid components are more difficult to specify and inspect and therefore are more difficult to purchase from outside vendors compared to rigid components

  2. Determination of geomagnetic archaeomagnitudes from clay pipes

    NASA Astrophysics Data System (ADS)

    Games, K. P.; Baker, M. E.

    1981-02-01

    Archaeomagnitude determinations of a selection of clay pipes dateable to AD 1645+/-10 as well as studies of pottery samples from the same site and of the same age have been made. Values of the magnitude of the ancient magnetic field (Banc), were obtained from two pottery sherds, two pipe bowls and three pipe stems. The values from the sherds and bowls agree within 2% and compare well with the average value of the magnitude of the magnetic field for the seventeenth century as determined by other archaeomagnetic studies. However, the pipe stems give values of Banc which are significantly less than those from the bowls and pottery. We have not yet been able to explain this and thus we suggest that reliable archaeomagnitude determinations can be made from the bowls of clay pipes but not from the stems. Nevertheless, this result provides a new source of material for investigating variations in the geomagnetic field strength over the past 400 yr. Clay pipes have been manufactured in England since the end of the sixteenth century. In the firing process some pipes were broken and disposed of without ever having been smoked. One such collection, discovered at Rainford, Lancashire, in 1978, consisted of a series of discrete dumps including pipes, kiln debris and a small collection of contemporary used earthenware sherds. The internal consideration of the dumps suggested a very short period of activity and archaeologists (P. Davey, personal communication) ascribe all the material to the period 1645+/-10 yr. With such well-dated material, we set out to check whether or not reliable archaeomagnitudes could be obtained from the pipes.

  3. Airport geomagnetic surveys in the United States

    USGS Publications Warehouse

    Berarducci, A.

    2006-01-01

    The Federal Aviation Administration (FAA) and the United States military have requirements for design, location, and construction of compass calibration pads (compass roses), these having been developed through collaboration with US Geological Survey (USGS) personnel. These requirements are detailed in the FAA Advisory Circular AC 150/5300-13, Appendix 4, and in various military documents, such as Handbook 1021/1, but the major requirement is that the range of declination measured within 75 meters of the center of a compass rose be less than or equal to 30 minutes of arc. The USGS Geomagnetism Group has developed specific methods for conducting a magnetic survey so that existing compass roses can be judged in terms of the needed standards and also that new sites can be evaluated for their suitability as potentially new compass roses. First, a preliminary survey is performed with a total-field magnetometer, with differences over the site area of less than 75nT being sufficient to warrant additional, more detailed surveying. Next, a number of survey points are established over the compass rose area and nearby, where declination is to be measured with an instrument capable of measuring declination to within 1 minute of arc, such as a Gurley transit magnetometer, DI Flux theodolite magnetometer, or Wild T-0. The data are corrected for diurnal and irregular effects of the magnetic field and declination is determined for each survey point, as well as declination range and average of the entire compass rose site. Altogether, a typical survey takes about four days to complete. ?? 2006 Springer.

  4. Simulations of the Geomagnetic Field Disturbances Caused by the Tunguska Event 1908

    NASA Astrophysics Data System (ADS)

    Kuzmicheva, M. Yu.; Losseva, T. V.

    2012-03-01

    The phenomena explaining the main features of geomagnetic perturbations caused by the Tunguska explosion: location, start time, and signs of disturbances of the geomagnetic field have been simulated. Azimuth of trajectory of the bolide has been defined.

  5. Patient comfort during flexible and rigid cystourethroscopy

    PubMed Central

    Zdrojowy, Romuald; Wojciechowska, Joanna; Kościelska, Katarzyna; Dembowski, Janusz; Matuszewski, Michał; Tupikowski, Krzysztof; Małkiewicz, Bartosz; Kołodziej, Anna

    2016-01-01

    Introduction Cystourethroscopy (CS) is an endoscopic method used to visualize the urethra and the bladder. Aim In this study, we prospectively evaluated pain in men undergoing cyclic cystoscopic assessment with rigid and flexible instruments after transurethral resection of bladder tumor (TURB). Material and methods One hundred and twenty male patients who were under surveillance after a TURB procedure due to urothelial cell carcinoma and who had undergone at least one rigid cystourethroscopy in the past were enrolled in the trial. Patients were prospectively randomized to age-matched groups for flexible (group F) or rigid (group R) CS. Patient's comfort was evaluated on an 11-grade scale, ranging from 0 (free from pain) to 10 points (unbearable pain). Results The patients described the pain during the previous rigid CS as ranging from 4 to 10 (mean: 6.8) in group F and from 0 to 10 (mean: 5.8) in group R. Group R patients described the pain during the current rigid CS as ranging from 0 to 10 (mean: 5.7). No mean change in the grade was observed between the two pain descriptions (no change 11 patients, weaker pain 25 patients, stronger pain 24 patients, gamma 0.51, p < 0.0001). Group F described the pain as 1 to 5 (mean: 2.1). In the case of flexible CS the pain experience was greatly lowered compared to the previous rigid CS. All flexible CS patients reported lowered pain (by 1 to 9 grades). Patients’ age did not influence the comfort of the flexible CS or the change in pain level. Conclusions Flexible CS is better tolerated than rigid cystoscopy by male patients regardless of patients’ age. PMID:27458489

  6. F layer positive response to a geomagnetic storm - June 1972

    NASA Technical Reports Server (NTRS)

    Miller, N. J.; Grebowsky, J. M.; Mayr, H. G.; Harris, I.; Tulunay, Y. K.

    1979-01-01

    A circulation model of neutral thermosphere-ionosphere coupling is used to interpret in situ spacecraft measurements taken during a topside midlatitude ionospheric storm. The data are measurements of electron density taken along the circular polar orbit of Ariel 4 at 550 km during the geomagnetically disturbed period June 17-18, 1972. It is inferred that collisional momentum transfer from the disturbed neutral thermosphere to the ionosphere was the dominant midday process generating the positive F-layer storm phase in the summer hemisphere. In the winter hemisphere the positive storm phase drifted poleward in the apparent response to magnetospheric E x B drifts. A summer F-layer positive phase developed at the sudden commencement and again during the geomagnetic main phase; a winter F-layer positive phase developed only during the geomagnetic main phase. The observed seasonal differences in both the onsets and the magnitudes of the positive phases are attributed to the interhemispheric asymmetry in thermospheric dynamics.

  7. Response of the high-latitude thermosphere to geomagnetic activity

    SciTech Connect

    Rees, D.

    1985-01-01

    Fuller-Rowell and Rees (1980) and Roble et al. (1982) have developed three-dimensional, time-dependent models which simulate the structure and dynamics of the thermosphere with considerable realism. These models are particularly useful for the evaluation of the individual contributions of the many distinct elements of the geomagnetic forcing of the polar thermosphere. A description is given of simulations of the steady-state structure and dynamics of the thermosphere for a level of moderately high solar activity, at the December and June solstices, and for moderately quiet and rather disturbed geomagnetic conditions. In the present paper, the simulations are used for reference purposes. Attention is given to time-dependent simulations of the thermospheric response to large geomagnetic disturbances. 24 references.

  8. Magnetospheric mapping with a quantitative geomagnetic field model

    NASA Technical Reports Server (NTRS)

    Fairfield, D. H.; Mead, G. D.

    1975-01-01

    Mapping the magnetosphere on a dipole geomagnetic field model by projecting field and particle observations onto the model is described. High-latitude field lines are traced between the earth's surface and their intersection with either the equatorial plane or a cross section of the geomagnetic tail, and data from low-altitude orbiting satellites are projected along field lines to the outer magnetosphere. This procedure is analyzed, and the resultant mappings are illustrated. Extension of field lines into the geomagnetic tail and low-altitude determination of the polar cap and cusp are presented. It is noted that while there is good agreement among the various data, more particle measurements are necessary to clear up statistical uncertainties and to facilitate comparison of statistical models.

  9. Midlatitude cooling caused by geomagnetic field minimum during polarity reversal.

    PubMed

    Kitaba, Ikuko; Hyodo, Masayuki; Katoh, Shigehiro; Dettman, David L; Sato, Hiroshi

    2013-01-22

    The climatic effects of cloud formation induced by galactic cosmic rays (CRs) has recently become a topic of much discussion. The CR-cloud connection suggests that variations in geomagnetic field intensity could change climate through modulation of CR flux. This hypothesis, however, is not well-tested using robust geological evidence. Here we present paleoclimate and paleoenvironment records of five interglacial periods that include two geomagnetic polarity reversals. Marine oxygen isotope stages 19 and 31 contain both anomalous cooling intervals during the sea-level highstands and the Matuyama-Brunhes and Lower Jaramillo reversals, respectively. This contrasts strongly with the typical interglacial climate that has the temperature maximum at the sea-level peak. The cooling occurred when the field intensity dropped to <40% of its present value, for which we estimate >40% increase in CR flux. The climate warmed rapidly when field intensity recovered. We suggest that geomagnetic field intensity can influence global climate through the modulation of CR flux.

  10. The geomagnetic elements in Denmark 1928-1980

    NASA Astrophysics Data System (ADS)

    Hansen, H. A.

    Geomagnetic surveys in Denmark from 1928 till 1980 are reported. The Danish Meteorological Institute initiated a new, geomagnetic survey of Denmark in 1928 by the establishment of 10 repeat statins for observation of the geomagnetic, secular variation. The stations were visited again in 1930 and since then every fifth year. The general survey was started in 1939 and continued during the years 1946 to 1957 with the mapping of Northern Jutland. In 1967 the survey taken with a coarser spacing of the measured points during the following years succeeded in completing the mapping of the country with primary consideration to the declination. The observations on the repeat stations during the time 1928-1980 allowed development of mathematical formulas for the secular change of the magnetic elements D, H and Z at any arbitrary point in the country.

  11. Geomagnetic observations on tristan da cunha, south atlantic ocean

    USGS Publications Warehouse

    Matzka, J.; Olsen, N.; Maule, C.F.; Pedersen, L.W.; Berarducci, A.M.; Macmillan, S.

    2009-01-01

    Few geomagnetic ground observations exist of the Earth's strongest core field anomaly, the South Atlantic Anomaly (SAA). The geomagnetic repeat station on the island Tristan da Cunha, located half-way between South Africa and South America at 37?? 05' S, 12?? 18' W, is therefore of crucial importance. We have conducted several sets of repeat station measurements during magnetically quiet conditions (Kp 2o or less) in 2004. The procedures are described and the results are compared to those from earlier campaigns and to the predictions of various global field models. Features of the local crustal bias field and the solar quiet daily variation are discussed. We also evaluate the benefit of continuous magnetic field recordings from Tristan da Cunha, and argue that such a data set is a very valuable addition to geomagnetic satellite data. Recently, funds were set up to establish and operate a magnetometer station on Tristan da Cunha during the Swarm magnetic satellite mission (2011-2014).

  12. Anomalous propagation of Omega VLF waves near the geomagnetic equator

    NASA Astrophysics Data System (ADS)

    Ohtani, A.; Kikuchi, T.; Nozaki, K.; Kurihara, N.; Kuratani, Y.; Ohse, M.

    1983-09-01

    Omega HAIKU, REUNION, and LIBERIA signals were received and anomalous propagation characteristics were obtained near the geomagnetic equator. Short-period fluctuations were found in the phase of the HAIKU 10.2 kHz signal in November 1979 and in the phase and amplitude of the HAIKU 13.6 kHz signal in November 1981. These cyclic fluctuations are in close correlation with the phase cycle slippings, which occur most frequently when the receiver is located at 6 S geomagnetic latitude. On the basis of anisotropic waveguide mode theory indicating much less attenuation in WE propagation than in EW propagation at the geomagnetic equator, it is concluded that the short-period fluctuations in the phase and amplitude are due to interference between the short-path and the long-path signals.

  13. Report of geomagnetic pulsation indices for space weather applications

    USGS Publications Warehouse

    Xu, Z.; Gannon, Jennifer L.; Rigler, Erin J.

    2013-01-01

    The phenomenon of ultra-low frequency geomagnetic pulsations was first observed in the ground-based measurements of the 1859 Carrington Event and has been studied for over 100 years. Pulsation frequency is considered to be “ultra” low when it is lower than the natural frequencies of the plasma, such as the ion gyrofrequency. Ultra-low frequency pulsations are considered a source of noise in some geophysical analysis techniques, such as aeromagnetic surveys and transient electromagnetics, so it is critical to develop near real-time space weather products to monitor these geomagnetic pulsations. The proper spectral analysis of magnetometer data, such as using wavelet analysis techniques, can also be important to Geomagnetically Induced Current risk assessment.

  14. Regional Geomagnetic Field Model for Croatia at 2009.5

    NASA Astrophysics Data System (ADS)

    Vujić, Eugen; Brkić, Mario; Kovács, Peter

    2016-02-01

    Geomagnetic data of north, east, and vertical components at Croatian repeat stations and ground survey sites, as well as European geomagnetic observatories and repeat stations, were used to obtain a regional geomagnetic model over Croatia at 2009.5 epoch. Different models were derived, depending on input data, and three modelling techniques were used: Taylor Polynomial, Adjusted Spherical Harmonic Analysis, and Spherical Harmonic Analysis. It was derived that the most accurate model over Croatia was the one when only Croatian data were used, and by using the Adjusted Spherical Harmonic Analysis. Based on Croatian repeat stations' data in the interval 2007.5-2010.5, and a global Enhanced Magnetic Model, it was possible to estimate the crustal field at those sites. It was also done by taking into account the empirical adjustment for long-term external field variations. The higher crustal field values were found at those stations which are on or close to the Adriatic anomaly.

  15. Geomagnetic inverse problem and data assimilation: a progress report

    NASA Astrophysics Data System (ADS)

    Aubert, Julien; Fournier, Alexandre

    2013-04-01

    In this presentation I will present two studies recently undertaken by our group in an effort to bring the benefits of data assimilation to the study of Earth's magnetic field and the dynamics of its liquid iron core, where the geodynamo operates. In a first part I will focus on the geomagnetic inverse problem, which attempts to recover the fluid flow in the core from the temporal variation of the magnetic field (known as the secular variation). Geomagnetic data can be downward continued from the surface of the Earth down to the core-mantle boundary, but not further below, since the core is an electrical conductor. Historically, solutions to the geomagnetic inverse problem in such a sparsely observed system were thus found only for flow immediately below the core mantle boundary. We have recently shown that combining a numerical model of the geodynamo together with magnetic observations, through the use of Kalman filtering, now allows to present solutions for flow throughout the core. In a second part, I will present synthetic tests of sequential geomagnetic data assimilation aiming at evaluating the range at which the future of the geodynamo can be predicted, and our corresponding prospects to refine the current geomagnetic predictions. Fournier, Aubert, Thébault: Inference on core surface flow from observations and 3-D dynamo modelling, Geophys. J. Int. 186, 118-136, 2011, doi: 10.1111/j.1365-246X.2011.05037.x Aubert, Fournier: Inferring internal properties of Earth's core dynamics and their evolution from surface observations and a numerical geodynamo model, Nonlinear Proc. Geoph. 18, 657-674, 2011, doi:10.5194/npg-18-657-2011 Aubert: Flow throughout the Earth's core inverted from geomagnetic observations and numerical dynamo models, Geophys. J. Int., 2012, doi: 10.1093/gji/ggs051

  16. 21 CFR 876.3630 - Penile rigidity implant.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Penile rigidity implant. 876.3630 Section 876.3630...) MEDICAL DEVICES GASTROENTEROLOGY-UROLOGY DEVICES Prosthetic Devices § 876.3630 Penile rigidity implant. (a) Identification. A penile rigidity implant is a device that consists of a pair of semi-rigid rods implanted in...

  17. 49 CFR 178.706 - Standards for rigid plastic IBCs.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 3 2014-10-01 2014-10-01 false Standards for rigid plastic IBCs. 178.706 Section... Performance-Oriented Standards § 178.706 Standards for rigid plastic IBCs. (a) The provisions in this section apply to rigid plastic IBCs intended to contain solids or liquids. Rigid plastic IBC types...

  18. 49 CFR 178.706 - Standards for rigid plastic IBCs.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 2 2010-10-01 2010-10-01 false Standards for rigid plastic IBCs. 178.706 Section... PACKAGINGS IBC Performance-Oriented Standards § 178.706 Standards for rigid plastic IBCs. (a) The provisions in this section apply to rigid plastic IBCs intended to contain solids or liquids. Rigid plastic...

  19. 49 CFR 178.706 - Standards for rigid plastic IBCs.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 3 2013-10-01 2013-10-01 false Standards for rigid plastic IBCs. 178.706 Section... Performance-Oriented Standards § 178.706 Standards for rigid plastic IBCs. (a) The provisions in this section apply to rigid plastic IBCs intended to contain solids or liquids. Rigid plastic IBC types...

  20. 49 CFR 178.706 - Standards for rigid plastic IBCs.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 3 2012-10-01 2012-10-01 false Standards for rigid plastic IBCs. 178.706 Section... Performance-Oriented Standards § 178.706 Standards for rigid plastic IBCs. (a) The provisions in this section apply to rigid plastic IBCs intended to contain solids or liquids. Rigid plastic IBC types...

  1. 49 CFR 178.706 - Standards for rigid plastic IBCs.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 3 2011-10-01 2011-10-01 false Standards for rigid plastic IBCs. 178.706 Section... Performance-Oriented Standards § 178.706 Standards for rigid plastic IBCs. (a) The provisions in this section apply to rigid plastic IBCs intended to contain solids or liquids. Rigid plastic IBC types...

  2. Rigidity loss in disordered network materials

    NASA Astrophysics Data System (ADS)

    Ellenbroek, Wouter G.; Hagh, Varda F.; Kumar, Avishek; Thorpe, M. F.; van Hecke, Martin

    Weakly jammed sphere packings show a very peculiar elasticity, with a ratio of compression modulus to shear modulus that diverges as the number of contacts approaches the minimum required for rigidity. Creating artificial isotropic network materials with this property is a challenge: so far, the least elaborate way to generate them is to actually simulate weakly compressed repulsive spheres. The next steps in designing such networks hinge upon a solid understanding of what properties of the sphere-packing derived network are essential for its elasticity. We elucidate the topological aspects of this question by comparing the rigidity transition in these networks to that in other random spring network models, including the common bond-diluted triangular net and a self-stress-free variant of that. We use the pebble game algorithm for identifying rigid clusters in mechanical networks to demonstrate that the marginally rigid state in sphere packings is perfectly isostatic everywhere, and the addition or removal of a single bond creates a globally stressed or globally floppy network, respectively. By contrast, the other classes of random network random networks show a more localized response to addition and removal of bonds, and, correspondingly, a more gradual rigidity transition.

  3. Crystal structure prediction of rigid molecules.

    PubMed

    Elking, Dennis M; Fusti-Molnar, Laszlo; Nichols, Anthony

    2016-08-01

    A non-polarizable force field based on atomic multipoles fit to reproduce experimental crystal properties and ab initio gas-phase dimers is described. The Ewald method is used to calculate both long-range electrostatic and 1/r(6) dispersion energies of crystals. The dispersion energy of a crystal calculated by a cutoff method is shown to converge slowly to the exact Ewald result. A method for constraining space-group symmetry during unit-cell optimization is derived. Results for locally optimizing 4427 unit cells including volume, cell parameters, unit-cell r.m.s.d. and CPU timings are given for both flexible and rigid molecule optimization. An algorithm for randomly generating rigid molecule crystals is described. Using the correct experimentally determined space group, the average and maximum number of random crystals needed to find the correct experimental structure is given for 2440 rigid single component crystals. The force field energy rank of the correct experimental structure is presented for the same set of 2440 rigid single component crystals assuming the correct space group. A complete crystal prediction is performed for two rigid molecules by searching over the 32 most probable space groups.

  4. GEOMAGNETIC REVERSALS DRIVEN BY ABRUPT SEA LEVEL CHANGES

    SciTech Connect

    Muller, R.A.; Morris, D.E.

    1986-10-01

    Changes in the moment of inertia of the earth, brought about by the redistribution of ocean water from the tropics to ice at high latitudes, couple energy from the spin of the earth into convection in the liquid core. This mechanism may help provide the driving energy for the earth's dynamo. Sufficiently rapid ocean level changes can disrupt the dynamo, resulting (in half of the cases) in a geomagnetic field reversal. The model can account for the previously mysterious correlation reported between geomagnetic reversals and mass extinctions.

  5. H-alpha response to geomagnetic disturbed activity at Arecibo.

    NASA Astrophysics Data System (ADS)

    Santos, Pedrina; Kerr, R.; Noto, J.; Brum, Christiano; Gonzalez, Sixto

    Configured with a spectral resolution of 0.0086 nm at 6563A, the low resolution Fabry-Perot Interferometer (FPI) installed at Arecibo Observatory sampled the geocoronal Balmer-alpha emission for sixty nights during new moon periods from September 2006 to September 2007. In this work two of these periods are analyzed according to the variability with the geomagnetic activity. With this purpose, the effect of the shadow height, local time and solar flux depen-dencies were found and isolated and only the possible variations due the geomagnetic activity were evaluated. The residuos of the relative H-alpha intensity and temperature are analyzed.

  6. Effects of a geomagnetic storm on thermospheric circulation. Master's thesis

    SciTech Connect

    Brinkman, D.G.

    1987-01-01

    The motions of the thermosphere and its interactions with the ionosphere during a geomagnetic storm are of current interest to space scientists. A two-dimensional model was used to simulate the thermospheric response to the impulsive high-latitude heating associated with a geomagnetic storm. The storm-induced motions can be characterized by an initial period of transient waves followed by the development of a mean circulation. These motions generate an electrical-current system that is on the same order of magnitude as, and in the opposite sense to the normal s/sub q/ current system. Model-simulated winds and electrical currents were then compared to observations.

  7. Poloidal and toroidal fields in geomagnetic field modeling

    NASA Astrophysics Data System (ADS)

    Backus, G.

    1986-02-01

    The application of surface operator theory to poloidal and toroidal fields in geomagnetic field modeling is described. Surface operators are obtained for the dimensionless surface gradient; the dimensionless surface curl; the dimensionless surface Laplacian, as well as for the Funk-Hecke operators, integral operators, and axisymmetric kernels. Methods are given for interpreting satellite measurements of the geomagnetic field B, assuming B is can vary significantly and rapidly with time, and there are electric fields in the sample. Approximation schemes for ionospheric currents are also described.

  8. Secular Variations of the Geomagnetic Field in Europe

    NASA Astrophysics Data System (ADS)

    Sas-Uhrynowski, A.; Welker, E.

    2009-09-01

    The international project MagNetE (Magnetic Net For Europe) was undertaken in 2003. The project has been accepted by the International Association of Geomagnetism and Aeronomy of the IUGG. The common research on the geomagnetic field space and time distribution in Europe, as well as collecting data and its analysis, constitutes the grounds for theoretical works on geomagnetic field models and their parameters. It is also the basis for studying the genesis of the geomagnetic field secular variations and its mechanism. The results of the project enable to increase the accuracy of models on the global, regional, and also on local scale. It has a vital meaning for the regions where the geomagnetic data are not available or, where the existing data, because of their low accuracy, cannot be used. Information about the secular variations of the geomagnetic field makes it possible to update the magnetic data, which is needed in navigation, topography, telecommunication, geology and geophysics and other domains. The enclosed maps of isopors presented have been compiled using the results of measuring campaigns in the years 2004-2006 together with the archive data. They show the secular variations of the magnetic declination D, the length H of the horizontal intensity vector and the lenght F of the total intensity vector of the geomagnetic field, in the intervals 1995-2000 and 2000-2005. The maps of isopors for Europe have been worked out using data from not only the magnetic observatories, but also from some hundred magnetic secular variation stations (repeated stations), located in 23 European countries. The secular variation differences between data obtained from terrestrial surveys and data from the IGRF model (International Geomagnetic Reference Field) have been presented in the form of maps and histograms. In several regions of Europe the unexpectedly large secular variation anomalies are visible. Anomalies of so high frequency and large amplitude cannot exist. They are

  9. Endoscope shaft-rigidity control mechanism: "FORGUIDE".

    PubMed

    Loeve, Arjo J; Plettenburg, Dick H; Breedveld, Paul; Dankelman, Jenny

    2012-02-01

    Recent developments in flexible endoscopy and other fields of medical technology have raised the need for compact slender shafts that can be made rigid and compliant at will. A novel compact mechanism, named FORGUIDE, with this functionality was developed. The FORGUIDE shaft rigidifies due to friction between a ring of cables situated between a spring and an inflated tube. A mathematical model for the FORGUIDE mechanism working principle was made and used to obtain understanding of this mechanism, predict the maximum rigidity of a FORGUIDE shaft design, and tune its design variables. The mathematical model gave suggestions for significant performance improvement by fine-tuning the design. A prototype FORGUIDE shaft was built and put to a series of bench tests. These tests showed that the FORGUIDE mechanism provides a reliable and simple way to control the rigidity of a flexible shaft.

  10. Quantum mechanics of a generalised rigid body

    NASA Astrophysics Data System (ADS)

    Gripaios, Ben; Sutherland, Dave

    2016-05-01

    We consider the quantum version of Arnold’s generalisation of a rigid body in classical mechanics. Thus, we quantise the motion on an arbitrary Lie group manifold of a particle whose classical trajectories correspond to the geodesics of any one-sided-invariant metric. We show how the derivation of the spectrum of energy eigenstates can be simplified by making use of automorphisms of the Lie algebra and (for groups of type I) by methods of harmonic analysis. We show how the method can be extended to cosets, generalising the linear rigid rotor. As examples, we consider all connected and simply connected Lie groups up to dimension 3. This includes the universal cover of the archetypical rigid body, along with a number of new exactly solvable models. We also discuss a possible application to the topical problem of quantising a perfect fluid.

  11. A statistical analysis of low frequency geomagnetic field pulsations at two Antarctic geomagnetic observatories in the polar cap region

    NASA Astrophysics Data System (ADS)

    Pietrolungo, M.; Lepidi, S.; Cafarella, L.; Di Mauro, D.

    2013-09-01

    The aim of this study is to investigate the characteristics of low frequency (˜0.5-5 mHz) geomagnetic field fluctuations as recorded at two Antarctic stations within the polar cap: the Italian observatory Mario Zucchelli Station (TNB) and the French-Italian observatory Dome C (DMC) in order to investigate the spatial extension and propagation characteristics of the phenomena observed at very high latitude. The stations have approximately the same geographic latitude, but a very different corrected geomagnetic latitude, being DMC close to the geomagnetic pole and TNB closer to the auroral oval. Our study focused on power spectra, coherence and phase difference between low frequency fluctuations analyzing the horizontal H component measured during the entire year 2006. The fluctuation power behavior during the day can be explained according to the positions of the stations with respect to the polar cap; indeed in the dayside sector it is higher in the cusp region, while in the nightside sector it is higher close to the geomagnetic pole. Furthermore the study of coherent fluctuations, focusing on their phase difference, indicated that the propagation direction within the cap is variable during the day: in the dayside and nightside regions it is from the auroral oval toward the geomagnetic pole, while in the magnetic local morning and afternoon sectors it is from the geomagnetic pole toward the dawn-dusk meridian. Finally the analysis of two individual pulsation events, consisting of short duration wave packets, is shown; it confirms the statistical considerations on the propagation direction and allows to estimate the wave number and apparent phase velocity, whose values are of the order of 3-4 and 30-15 km/s, respectively.

  12. Rigid spine syndrome and fatal cardiomyopathy.

    PubMed Central

    Colver, A F; Steer, C R; Godman, M J; Uttley, W S

    1981-01-01

    A 7 1/2-year-old girl had the clinical features of the rigid spine syndrome of Dubowitz. Muscle biopsy showed a predominance of type 2 fibres with neither myopathic features nor an increase in connective tissue. In addition, she had a hypertrophic cardiomyopathy with which she presented in heart failure and from which she died suddenly one month later. The association of rigid spine syndrome with cardiomyopathy has not been reported previously. Images Fig. 1 Fig. 2 Fig. 3 PMID:7193439

  13. Kinematic problem of rigid body orientation control

    NASA Astrophysics Data System (ADS)

    Plotnikov, P. K.; Sergeev, A. N.; Chelnokov, Iu. N.

    1991-10-01

    The problem of reducing a coordinate system linked with a rigid body to a reference coordinate system rotating with a specified (programmed) angular velocity is analyzed using a kinematic formulation. The mathematic model of motion includes kinematic equations of the angular motion of a rigid body in nonnormalized quaternions; used as the controls are projections of the absolute angular velocity of body rotation to the coordinate axes. Two kinds of correction are proposed which represent quaternion analogs of the positional and integral corrections. Linear error equations for the orientation control system are obtained for the types of correction proposed here.

  14. Thin structured rigid body for acoustic absorption

    NASA Astrophysics Data System (ADS)

    Starkey, T. A.; Smith, J. D.; Hibbins, A. P.; Sambles, J. R.; Rance, H. J.

    2017-01-01

    We present a thin acoustic metamaterial absorber, comprised of only rigid metal and air, that gives rise to near unity absorption of airborne sound on resonance. This simple, easily fabricated, robust structure comprising a perforated metal plate separated from a rigid wall by a deeply subwavelength channel of air is an ideal candidate for a sound absorbing panel. The strong absorption in the system is attributed to the thermo-viscous losses arising from a sound wave guided between the plate and the wall, defining the subwavelength channel.

  15. Rigid and semi rigid polyurethane resins: A structural investigation using DMA, SAXS and Le Bail method

    NASA Astrophysics Data System (ADS)

    Trovati, Graziella; Sanches, Edgar A.; de Souza, Sérgio M.; dos Santos, Amanda L.; Neto, Salvador C.; Mascarenhas, Yvonne P.; Chierice, Gilberto O.

    2014-10-01

    Two different types of polyurethane (PU) resins were synthesized with pre-polymer/polyol (-NCO/-OH) mass proportions of 1:1 (Rigid PU) and 1:1.5 (Semi rigid PU). Based on the results from Dynamic Mechanical Analysis (DMA), rigid PU showed a higher Storage Modulus (E‧) which may be related to the macromolecules crosslinking process. In contrast, the greater Loss Modulus (E″) in semi rigid PU was related to the greater ability to dissipate energy, suggesting that the change in polyol/pre-polymer ratio promotes structural changes in PU resins. Le Bail method was performed with a triclinic crystal structure (for rigid PU, a = 4.9117 (2) Å, b = 8.1103 (2) Å, c = 19.7224 (2) Å, α = 116.2831 (2)°, β = 125.4058 (2)° and γ = 83.6960 (2)°). Average crystallite size was found in the range of 26 (1) Å for rigid PU and somewhat smaller around 20 (1) Å for semi rigid PU. The Guinier radii of gyration (Rg) and the maximum particle sizes (Dmax) were calculated based on Small Angle X-ray Scattering (SAXS) curves. Two different values for Radii of gyration (Rg) were calculated, one obtained from Guinier’s plot using the program Microcal Origin 7.5 (RgORIGIN) and other from the pair-distance distribution function (p(r)) calculation, using the GNOM (RgGNOM) program package The possible highest values of (RgORIGIN) were obtained from Guinier’s curves. For rigid and semi rigid PU resins, the (RgORIGIN) values were, respectively, (320 ± 1) and (260 ± 1) Å. The average radii of gyration (RgGNOM) were obtained from the calculated pair-distance distribution function (p(r)). For rigid and semi rigid PU resins, the RgGNOM values were, respectively, (95 ± 1) Å and (86 ± 1) Å. Dmax values were obtained from the p(r) and ranged from (330 ± 3) Å to (260 ± 3) Å for rigid and semi rigid PU, respectively. Kratky curves showed that less organized systems were produced when the polyol amount was increased.

  16. Surface electric fields for North America during historical geomagnetic storms

    USGS Publications Warehouse

    Wei, Lisa H.; Homeier, Nichole; Gannon, Jennifer L.

    2013-01-01

    To better understand the impact of geomagnetic disturbances on the electric grid, we recreate surface electric fields from two historical geomagnetic storms—the 1989 “Quebec” storm and the 2003 “Halloween” storms. Using the Spherical Elementary Current Systems method, we interpolate sparsely distributed magnetometer data across North America. We find good agreement between the measured and interpolated data, with larger RMS deviations at higher latitudes corresponding to larger magnetic field variations. The interpolated magnetic field data are combined with surface impedances for 25 unique physiographic regions from the United States Geological Survey and literature to estimate the horizontal, orthogonal surface electric fields in 1 min time steps. The induced horizontal electric field strongly depends on the local surface impedance, resulting in surprisingly strong electric field amplitudes along the Atlantic and Gulf Coast. The relative peak electric field amplitude of each physiographic region, normalized to the value in the Interior Plains region, varies by a factor of 2 for different input magnetic field time series. The order of peak electric field amplitudes (largest to smallest), however, does not depend much on the input. These results suggest that regions at lower magnetic latitudes with high ground resistivities are also at risk from the effect of geomagnetically induced currents. The historical electric field time series are useful for estimating the flow of the induced currents through long transmission lines to study power flow and grid stability during geomagnetic disturbances.

  17. An empirical model of the quiet daily geomagnetic field variation

    USGS Publications Warehouse

    Yamazaki, Y.; Yumoto, K.; Cardinal, M.G.; Fraser, B.J.; Hattori, P.; Kakinami, Y.; Liu, J.Y.; Lynn, K.J.W.; Marshall, R.; McNamara, D.; Nagatsuma, T.; Nikiforov, V.M.; Otadoy, R.E.; Ruhimat, M.; Shevtsov, B.M.; Shiokawa, K.; Abe, S.; Uozumi, T.; Yoshikawa, A.

    2011-01-01

    An empirical model of the quiet daily geomagnetic field variation has been constructed based on geomagnetic data obtained from 21 stations along the 210 Magnetic Meridian of the Circum-pan Pacific Magnetometer Network (CPMN) from 1996 to 2007. Using the least squares fitting method for geomagnetically quiet days (Kp ??? 2+), the quiet daily geomagnetic field variation at each station was described as a function of solar activity SA, day of year DOY, lunar age LA, and local time LT. After interpolation in latitude, the model can describe solar-activity dependence and seasonal dependence of solar quiet daily variations (S) and lunar quiet daily variations (L). We performed a spherical harmonic analysis (SHA) on these S and L variations to examine average characteristics of the equivalent external current systems. We found three particularly noteworthy results. First, the total current intensity of the S current system is largely controlled by solar activity while its focus position is not significantly affected by solar activity. Second, we found that seasonal variations of the S current intensity exhibit north-south asymmetry; the current intensity of the northern vortex shows a prominent annual variation while the southern vortex shows a clear semi-annual variation as well as annual variation. Thirdly, we found that the total intensity of the L current system changes depending on solar activity and season; seasonal variations of the L current intensity show an enhancement during the December solstice, independent of the level of solar activity. Copyright 2011 by the American Geophysical Union.

  18. Possible helio-geomagnetic activity influence on cardiological cases

    NASA Astrophysics Data System (ADS)

    Katsavrias, Christos

    Eruptive solar events as flares and coronal mass ejections (CMEs) occur during solar activ-ity periods. Energetic particles, fast solar wind plasma and electromagnetic radiation pass through interplanetary space, arrive on Earth's ionosphere-magnetosphere and produce various disturbances. It is well known the negative influence of geomagnetic substorms on the human technological applications on geospace. During the last 25 years, many studies concerning the possible influence on the human health are published. Increase of the Acute Coronary Syn-dromes and disorders of the Cardiac Rhythm, increase of accidents as well as neurological and psychological disorders (e.g. increase of suicides) during or near to the geomagnetic storms time interval are reported. In this study, we research the problem in Greece, focusing on patients with Acute Myocardial Infraction, hospitalized in the 2nd Cardiological Department of the General Hospital of Nikaea (Piraeus City), for the time interval 1997-2007 (23rd solar cycle) and also to the arrival of emergency cardiological cases to Emergency Department of two greek hospitals, the General Hospital of Lamia City and the General Hospital of Veria City during the selected months, with or without helio-geomagnetic activity, of the 23rd solar cycle. Increase of cases is recorded during the periods with increase helio-geomagnetic activity. The necessity of continuing the research for a longer period and with a bigger sample is high; so as to exact more secure conclusions.

  19. Surface electric fields for North America during historical geomagnetic storms

    NASA Astrophysics Data System (ADS)

    Wei, Lisa H.; Homeier, Nicole; Gannon, Jennifer L.

    2013-08-01

    To better understand the impact of geomagnetic disturbances on the electric grid, we recreate surface electric fields from two historical geomagnetic storms—the 1989 "Quebec" storm and the 2003 "Halloween" storms. Using the Spherical Elementary Current Systems method, we interpolate sparsely distributed magnetometer data across North America. We find good agreement between the measured and interpolated data, with larger RMS deviations at higher latitudes corresponding to larger magnetic field variations. The interpolated magnetic field data are combined with surface impedances for 25 unique physiographic regions from the United States Geological Survey and literature to estimate the horizontal, orthogonal surface electric fields in 1 min time steps. The induced horizontal electric field strongly depends on the local surface impedance, resulting in surprisingly strong electric field amplitudes along the Atlantic and Gulf Coast. The relative peak electric field amplitude of each physiographic region, normalized to the value in the Interior Plains region, varies by a factor of 2 for different input magnetic field time series. The order of peak electric field amplitudes (largest to smallest), however, does not depend much on the input. These results suggest that regions at lower magnetic latitudes with high ground resistivities are also at risk from the effect of geomagnetically induced currents. The historical electric field time series are useful for estimating the flow of the induced currents through long transmission lines to study power flow and grid stability during geomagnetic disturbances.

  20. ISS Plasma Contactor Units Operations During Strong Geomagnetic Activity

    NASA Astrophysics Data System (ADS)

    Alred, J.; Mikatarian, R.; Barsamian, H.; Minow, J.; Koontz, S.

    2003-12-01

    The large structure and high voltage arrays of the ISS represent a complex system that interacts with the Earth's ionosphere. To mitigate spacecraft charging problems on the ISS, two Plasma Contactor Units discharge ionized xenon gas to "clamp" the potential of the ISS with respect to the low Earth orbit plasma. The Plasma Interaction Model, a model of ISS plasma interaction developed from the basic physics of the interaction phenomena, includes magnetic induction effects, plasma temperature and density effects, interaction of the high voltage solar arrays with ionospheric plasma, and accounts for other conductive areas on the ISS. To augment this model, the PCU discharge current has been monitored for the ISS in a variety of flight attitudes as well as during the annual seasons. A review of the PCU discharge currents shows a correlation to the geomagnetic activity. The variation in the PCU discharge current during strong geomagnetic activity will be presented. Also, the PCU discharge currents during periods of low geomagnetic activity will be discussed. The presentation will conclude with a comparison of satellite plasma measurements during different stages of geomagnetic activity.

  1. Solar Activity, Different Geomagnetic Activity Levels and Acute Myocardial Infarction

    NASA Astrophysics Data System (ADS)

    Dimitrova, Svetla; Jordanova, Malina; Stoilova, Irina; Taseva, Tatiana; Maslarov, Dimitar

    Results on revealing a possible relationship between solar activity (SA) and geomagnetic activity (GMA) and acute myocardial infarction (AMI) morbidity are presented. Studies were based on medical data covering the period from 1.12.1995 to 31.12.2004 and concerned daily distribution of patients with AMI diagnose (in total 1192 cases) from Sofia region on the day of admission at the hospital. Analysis of variance (ANOVA) was applied to check the significance of GMA intensity effect and the type of geomagnetic storms, those caused by Magnetic Clouds (MC) and by High Speed Solar Wind Streams (HSSWS), on AMI morbidity. Relevant correlation coefficients were calculated. Results revealed statistically significant positive correlation between considered GMA indices and AMI. ANOVA revealed that AMI number was signifi- cantly increased from the day before (-1st) till the day after (+1st) geomagnetic storms with different intensities. Geomagnetic storms caused by MC were related to significant increase of AMI number in comparison with the storms caused by HSSWS. There was a trend for such different effects even on -1st and +1st day.

  2. The Use of Dispersion Relations For The Geomagnetic Transfer Functions

    NASA Astrophysics Data System (ADS)

    Marcuello, A.; Queralt, P.; Ledo, J. J.

    The magnetotelluric responses are complex magnitudes, where real and imaginary parts contain the same information on the geoelectrical structure. It seems possible, from very general hypotheses on the geoelectrical models (causality, stability and passivity), to apply the Kramers-Krönig dispersion relations to the magnetotelluric responses (impedance, geomagnetic transfer functions,...). In particular, the applica- bility of these relations to the impedance is a current point of discussion, but there are not many examples of their application to the geomagnetic transfer functions (tipper). The aim of this paper is to study how the relations of dispersion are applied to the real and imaginary part of the geomagnetic transfer functions, and to check its validity. For this reason, we have considered data (or responses) from two- and three-dimensional structures, and for these data, we have taken two situations: 1.- Responses that have been synthetically generated from numerical modelling, that allows us to control the quality of the data. 2.- Responses obtained from fieldwork, that are affected by exper- imental error. Additionally, we have also explored the use of these relations to extrap- olate the geomagnetic transfer functions outside the interval of measured frequencies, in order to obtain constrains on the values of these extrapolated data. The results have shown that the dispersion relations are accomplished for the geomag- netic transfer functions, and they can offer information about how these responses are behaved outside (but near) the range of measured frequencies.

  3. On statistical relationship of solar, geomagnetic and human activities.

    PubMed

    Alania, M V; Gil, A; Modzelewska, R

    2004-01-01

    Data of galactic cosmic rays, solar and geomagnetic activities and solar wind parameters on the one side and car accident events (CAE) in Poland on the other have been analyzed in order to reveal the statistical relationships among them for the period of 1990-2001. Cross correlation and cross spectrum of the galactic cosmic ray intensity, the solar wind (SW) velocity, Kp index of geomagnetic activity and CAE in Poland have been carried out. It is shown that in some epochs of the above-mentioned period there is found a reliable relationship between CAE and solar and geomagnetic activities parameters in the range of the different periodicities, especially, 7 days. The periodicity of 7 days revealed in the data of the CAE has the maximum on Friday without any exception for the minimum and maximum epochs of solar activity. However, the periodicity of 7 days is reliably revealed in other parameters characterizing galactic cosmic rays, SW, solar and geomagnetic activities, especially for the minimum epoch of solar activity. The periodicity of 3.5 days found in the series of CAE data more or less can be completely ascribed to the social effects, while the periodicity of 7 days can be ascribed to the social effect or/to the processes on the Sun, in the interplanetary space and in the Earth's magnetosphere and atmosphere.

  4. Statistical Relationship between Sawtooth Oscillations and Geomagnetic Storms

    NASA Astrophysics Data System (ADS)

    Kim, Jae-Hun; Lee, Dae-Young; Choi, Cheong-Rim; Her, Young-Tae; Han, Jin-Wook; Hong, Sun-Hak

    2008-06-01

    We have investigated a statistical relationship between sawtooth oscillations and geomagnetic storms during 2000-2004. First of all we selected a total of 154 geomagnetic storms based on the Dst index, and distinguished between different drivers such as Coronal Mass Ejection (CME) and Co-rotating Interaction Region (CIR). Also, we identified a total of 48 sawtooth oscillation events based on geosynchronous energetic particle data for the same 2000-2004 period. We found that out of the 154 storms identified, 47 storms indicated the presence of sawtooth oscillations. Also, all but one sawtooth event identified occurred during a geomagnetic storm interval. It was also found that sawtooth oscillation events occur more frequently for storms driven by CME (˜62%) than for storms driven by CIR (˜30%). In addition, sawtooth oscillations occurred mainly (˜82%) in the main phase of storms for CME-driven storms while they occurred mostly (˜78%) during the storm recovery phase for CIR-driven storms. Next we have examined the average characteristics of the Bz component of IMF, and solar wind speed, which were the main components for driving geomagnetic storm. We found that for most of the sawtooth events, the IMF Bz corresponds to --15 to 0 nT and the solar wind speed was in the range of 400˜700 km/s. We found that there was a weak tendency that the number of teeth for a given sawtooth event interval was proportional to the southward IMF Bz magnitude.

  5. (abstract) A Geomagnetic Contribution to Climate Change in this Century

    NASA Technical Reports Server (NTRS)

    Feynman, J.; Ruzmaikin, A.; Lawrence, J.

    1996-01-01

    There is a myth that all solar effects can be parameterized by the sun spot number. This is not true. For example, the level of geomagnetic activity during this century was not proportional to the sunspot number. Instead there is a large systematic increase in geomagnetic activity, not reflected in the sunspot number. This increase occurred gradually over at least 60 years. The 11 year solar cycle variation was superimposed on this systematic increase. Here we show that this systematic increase in activity is well correlated to the simultaneous increase in terrestrial temperature that occurred during the first half of this century. We discuss these findings in terms of mechanisms by which geomagnetics can be coupled to climate. These mechanisms include possible changes in weather patterns and cloud cover due to increased cosmic ray fluxes, or to increased fluxes of high energy electrons. We suggest that this systematic increase in geomagnetic activity contributed (along with anthropogenic effects and possible changes in solar irradiance) to the changes in climate recorded during this period.

  6. New insights on geomagnetic storms from observations and modeling

    SciTech Connect

    Jordanova, Vania K

    2009-01-01

    Understanding the response at Earth of the Sun's varying energy output and forecasting geomagnetic activity is of central interest to space science, since intense geomagnetic storms may cause severe damages on technological systems and affect communications. Episodes of southward (Bzgeomagnetic conditions are associated either with coronal mass ejections (CMEs) and possess long and continuous negative IMF Bz excursions, or with high speed solar wind streams (HSS) whose geoeffectiveness is due to IMF Bz profiles fluctuating about zero with various amplitudes and duration. We show examples of ring current simulations during two geomagnetic storms representative of each interplanetary condition with our kinetic ring current atmosphere interactions model (RAM), and investigate the mechanisms responsible for trapping particles and for causing their loss. We find that periods of increased magnetospheric convection coinciding with enhancements of plasma sheet density are needed for strong ring current buildup. During the HSS-driven storm the convection potential is highly variable and causes small sporadic injections into the ring current. The long period of enhanced convection during the CME-driven storm causes a continuous ring current injection penetrating to lower L shells and stronger ring current buildup.

  7. The risk characteristics of solar and geomagnetic activity

    NASA Astrophysics Data System (ADS)

    Podolska, Katerina

    2016-04-01

    The main aim of this contribution is a deeper analysis of the influence of solar activity which is expected to have an impact on human health, and therefore on mortality, in particular civilization and degenerative diseases. We have constructed the characteristics that represent the risk of solar and geomagnetic activity on human health on the basis of our previous analysis of association between the daily numbers of death on diseases of the nervous system and diseases of the circulatory system and solar and geomagnetic activity in the Czech Republic during the years 1994 - 2013. We used long period daily time series of numbers of deaths by cause, long period time series of solar activity indices (namely R and F10.7), geomagnetic indicies (Kp planetary index, Dst) and ionospheric parameters (foF2 and TEC). The ionospheric parameters were related to the geographic location of the Czech Republic and adjusted for middle geographic latitudes. The risk characteristics were composed by cluster analysis in time series according to the phases of the solar cycle resp. the seasonal insolation at mid-latitudes or the daily period according to the impact of solar and geomagnetic activity on mortality by cause of death from medical cause groups of death VI. Diseases of the nervous system and IX. Diseases of the circulatory system mortality by 10th Revision of International Classification of Diseases WHO (ICD-10).

  8. Investigating dynamical complexity of geomagnetic jerks using various entropy measures

    NASA Astrophysics Data System (ADS)

    Balasis, Georgios; Potirakis, Stelios; Mandea, Mioara

    2016-06-01

    Recently, many novel concepts originated in dynamical systems or information theory have been developed, partly motivated by specific research questions linked to geosciences, and found a variety of different applications. This continuously extending toolbox of nonlinear time series analysis highlights the importance of the dynamical complexity to understand the behavior of the complex Earth's system and its components. Here, we propose to apply such new approaches, mainly a series of entropy methods to the time series of the geomagnetic field. Two datasets provided by Chambon la Foret (France) and Niemegk (Germany) observatories are considered for analysis to detect dynamical complexity changes associated with geomagnetic jerks, the abrupt changes in the second temporal derivative of the Earth's magnetic field. The results clearly demonstrate the ability of Shannon and Tsallis entropies as well as Fisher information to detect events in a regional manner having identified complexities lower than the background in time intervals when geomagnetic jerks have already been reported in the literature. Additionally, these information measures are directly applicable to the original data without having to derive the secular variation or acceleration from the observatory monthly means. The strength of the proposed analysis to reveal dynamical complexity features associated with geomagnetic jerks can be utilized for analyzing not only ground measurements, but also satellite data, as those provided by the current magnetic field mission of Swarm.

  9. Rigid Body Modes Influence On Microvibration Analysis-Application To Swarm

    NASA Astrophysics Data System (ADS)

    Laduree, G.; Fransen, S.; Baldesi, G.; Pflieger, I.

    2012-07-01

    Microvibrations are defined as low level mechanical disturbances affecting payload performance, generated by mobile parts or mechanism operating on-board the spacecraft, like momentum or reaction wheels, pointing mechanism, cryo-coolers or thrusters. The disturbances caused by these sources are transmitted through the spacecraft structure and excite modes of that structure or elements of the payload impacting its performance (e.g. Line of sight rotations inducing some image quality degradation). The dynamic interaction between these three elements (noise source, spacecraft structure and sensitive receiver) makes the microvibration prediction a delicate problem. Microvibration sources are generally of concern in the frequency range from a few Hz to 1000 Hz. However, in some specific cases, high stability at lower frequencies might be requested. This is the case of the SWARM mission, whose objectives are to provide the best ever survey of the geomagnetic field and its temporal evolution as well as supplementary information for studying the interaction of the magnetic field with other physical quantities describing the Earth system (e.g. ocean circulation). Among its instruments, SWARM is embarking a very sensitive 6-axis accelerometer in the low frequency range (10-8 m/s2 or rad/s2 between 10-4 and 0.1 Hz) located at its Centre of Gravity and an Absolute Scalar Magnetometer located at the tip of a boom far from the spacecraft body. The ASM performs its measurements by rotating an alternative magnetic field around its main axis thanks to a piezo-electric motor. This repeated disturbance might generate some pollution of the accelerometer science data. The objective of this work is to focus on the interaction of the rigid body mode calculation method with the elastic contribution of the normal modes excited by the noise source frequency content. It has indeed been reported in the past that NASTRAN Lanczos rigid body modes may lead to inaccurate rigid-body accelerations

  10. Assessment of extreme values in geomagnetic and geoelectric field variations for Canada

    NASA Astrophysics Data System (ADS)

    Nikitina, L.; Trichtchenko, L.; Boteler, D. H.

    2016-07-01

    Disturbances of the geomagnetic field produced by space weather events can have an impact on power systems and other critical infrastructure. To mitigate these risks it is important to determine the extreme values of geomagnetic activity that can occur. More than 40 years of 1 min magnetic data recorded at 13 Canadian geomagnetic observatories have been analyzed to evaluate extreme levels in geomagnetic and geoelectric activities in different locations of Canada. The hourly ranges of geomagnetic field variations and hourly maximum in rate of change of the magnetic variations have been used as measures of geomagnetic activity. Geoelectric activity is estimated by the hourly peak amplitude of the geoelectric fields calculated with the use of Earth resistivity models specified for different locations in Canada. A generalized extreme value distribution was applied to geomagnetic and geoelectric indices to evaluate extreme geomagnetic and geoelectric disturbances, which could happen once per 50 and once per 100 years with 99% confidence interval. Influence of geomagnetic latitude and Earth resistivity models on the results for the extreme geomagnetic and geoelectric activity is discussed. The extreme values provide criteria for assessing the vulnerability of power systems and other technology to geomagnetic activity for design or mitigation purposes.

  11. An Introduction to Data Assimilation and Predictability in Geomagnetism

    NASA Astrophysics Data System (ADS)

    Fournier, Alexandre; Hulot, Gauthier; Jault, Dominique; Kuang, Weijia; Tangborn, Andrew; Gillet, Nicolas; Canet, Elisabeth; Aubert, Julien; Lhuillier, Florian

    2010-08-01

    Data assimilation in geomagnetism designates the set of inverse methods for geomagnetic data analysis which rely on an underlying prognostic numerical model of core dynamics. Within that framework, the time-dependency of the magnetohydrodynamic state of the core need no longer be parameterized: The model trajectory (and the secular variation it generates at the surface of the Earth) is controlled by the initial condition, and possibly some other static control parameters. The primary goal of geomagnetic data assimilation is then to combine in an optimal fashion the information contained in the database of geomagnetic observations and in the dynamical model, by adjusting the model trajectory in order to provide an adequate fit to the data. The recent developments in that emerging field of research are motivated mostly by the increase in data quality and quantity during the last decade, owing to the ongoing era of magnetic observation of the Earth from space, and by the concurrent progress in the numerical description of core dynamics. In this article we review briefly the current status of our knowledge of core dynamics, and elaborate on the reasons which motivate geomagnetic data assimilation studies, most notably (a) the prospect to propagate the current quality of data backward in time to construct dynamically consistent historical core field and flow models, (b) the possibility to improve the forecast of the secular variation, and (c) on a more fundamental level, the will to identify unambiguously the physical mechanisms governing the secular variation. We then present the fundamentals of data assimilation (in its sequential and variational forms) and summarize the observations at hand for data assimilation practice. We present next two approaches to geomagnetic data assimilation: The first relies on a three-dimensional model of the geodynamo, and the second on a quasi-geostrophic approximation. We also provide an estimate of the limit of the predictability of

  12. Rigid polyurethane and kenaf core composite foams

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Rigid polyurethane foams are valuable in many construction applications. Kenaf is a bast fiber plant where the surface stem skin provides bast fibers whose strength-to-weight ratio competes with glass fiber. The higher volume product of the kenaf core is an under-investigated area in composite appli...

  13. Number Rigidity in Superhomogeneous Random Point Fields

    NASA Astrophysics Data System (ADS)

    Ghosh, Subhro; Lebowitz, Joel

    2017-02-01

    We give sufficient conditions for the number rigidity of a large class of point processes in dimension d=1 and 2, based on the decay of correlations. Number rigidity implies that the probability distribution of the number of particles in a bounded domain Λ subset R^d, conditional on the configuration on Λ ^\\complement , is concentrated on a single integer N_Λ . Our conditions are: (a) ρ _1(x)= - int _{R^d} ρ _tr^{(2)}(x,y) dy for all x, where ρ _1 and ρ _tr^{(2)} are the intensity and the truncated pair correlation function resp., and (b)|ρ _tr^{(2)}(x,y)| is bounded by C_1[|x-y|+1]^{-2} in d=1 and by C_2[|x-y|+1]^{-(4+ɛ)} in d=2. Condition (a) covers a wide class of processes, including translation invariant or periodic point process on R^d, d=1,2, that are superhomogeneous or hyperuniform (that is the variance of the number of particles in a bounded domain Ω subset R^d grows slower than the volume of Ω ). It also covers determinantal point processes having a projection kernel. Our conditions for number rigidity are satisfied by all known processes with number rigidity in d=1,2. We also observe, in the light of the results of [26], that no such criteria exist in d>2.

  14. Balancing of Rigid and Flexible Rotors

    DTIC Science & Technology

    1986-01-01

    rotor conr- Igjurations that can be "dialed In" are shown at left. (Cour- tesy of’ Schenak Trebel Corporation.) ŕ 1,4 BALANJCING MACHINES ANI...anice, For all rigid rotors in any grado , the specific balance requirement for that grade should provide smooth operation. Tlhe grstde number represents

  15. Plastic flow around rigid spherical inclusions

    NASA Technical Reports Server (NTRS)

    Ruoff, A. L.; Nelson, D. A., Jr.

    1974-01-01

    The extent of plastic flow in a spherical solid (assumed to be homogeneous and elastically and plastically isotropic), surrounding a concentric rigid sphere was calculated as a function of applied external pressure. The applied pressure necessary to cause plastic deformation throughout the solid was obtained.

  16. Rigid rod anchored to infinite membrane.

    PubMed

    Guo, Kunkun; Qiu, Feng; Zhang, Hongdong; Yang, Yuliang

    2005-08-15

    We investigate the shape deformation of an infinite membrane anchored by a rigid rod. The density profile of the rod is calculated by the self-consistent-field theory and the shape of the membrane is predicted by the Helfrich membrane elasticity theory [W. Helfrich, Z. Naturforsch. 28c, 693 (1973)]. It is found that the membrane bends away from the rigid rod when the interaction between the rod and the membrane is repulsive or weakly attractive (adsorption). However, the pulled height of the membrane at first increases and then decreases with the increase of the adsorption strength. Compared to a Gaussian chain with the same length, the rigid rod covers much larger area of the membrane, whereas exerts less local entropic pressure on the membrane. An evident gap is found between the membrane and the rigid rod because the membrane's curvature has to be continuous. These behaviors are compared with that of the flexible-polymer-anchored membranes studied by previous Monte Carlo simulations and theoretical analysis. It is straightforward to extend this method to more complicated and real biological systems, such as infinite membrane/multiple chains, protein inclusion, or systems with phase separation.

  17. Quantification of the UPDRS Rigidity Scale.

    PubMed

    Patrick, S K; Denington, A A; Gauthier, M J; Gillard, D M; Prochazka, A

    2001-03-01

    In the clinical setting, parkinsonian rigidity is assessed using subjective rating scales such as that of the Unified Parkinson's Disease Rating System (UPDRS). However, such scales are susceptible to problems of sensitivity and reliability. Here, we evaluate the reliability and validity of a device designed to quantify parkinsonian rigidity at the elbow and the wrist. The method essentially quantifies the clinical examination and employs small sensors to monitor forces and angular displacements imposed by the clinician onto the limb segment distal to the joint being evaluated. Force and displacement data are used to calculate elastic and viscous stiffnesses and their vectorial sum, mechanical impedance. Interexaminer agreement of measures of mechanical impedance in subjects with Parkinson's disease was comparable to that of clinical UPDRS scores. Examiners tended to overrate rigidity on the UPDRS scale during reinforcement manoeuvres. Mechanical impedance was nonlinearly related to UPDRS ratings of rigidity at the elbow and wrist; characterization of such relationships allows interpretation of impedance measurements in terms of the clinical rating scales.

  18. Analysis and Modeling of Rigid Microswimmers

    NASA Astrophysics Data System (ADS)

    Meshkati, Farshad

    In this thesis, we investigate magnetically actuated rigid microswimmers based on analytical and numerical schemes. These swimming micro-robots have medical applications such as drug delivery and in vivo diagnostics. Our model employs the method of regularized Stokeslets to faithfully incorporate the low-Reynolds-number hydrodynamics of arbitrary rigid geometries. We show how these magnetized swimmers can be actuated and controlled by externally rotating uniform magnetic fields. Our model predicts the swimming characteristics such as speed and direction. We show how to determine the dynamic stability of steadily rotating microswimmers. First, we address what is the simplest geometry capable of swimming. We illustrate that, despite the common belief that rigid microswimmers need to be chiral to be able to cause propulsion, a simple achiral 3-bead geometry can exhibit appreciable propulsion and controllability. We generalize this to explain the minimum geometric requirements for rigid rotating propulsion based on a symmetry analysis. Next, we investigate the implications of the stability analysis on the control of the 3-bead swimmer. We show that by adjusting the angle between the magnetic field and its rotation, one can control the existence of multiple stable rotation modes, leading to control of swimming direction and speed.

  19. Phosphorescence and Energy Transfer in Rigid Solutions.

    ERIC Educational Resources Information Center

    Enciso, E.; Cabello, A.

    1980-01-01

    Describes an experiment which illustrates the general aspects of intermolecular energy transfer between triplet states in rigid solutions of organic compounds solved in an ethanol-ether mixture. Measurements of quenching and energy transfer processes are made using the chemicals of benzophenone and naphthalene. (CS)

  20. Multiple-Purpose Rigid Foam Insulation

    NASA Technical Reports Server (NTRS)

    Liu, Matthew T.

    1989-01-01

    Plastic foam promises to serve as multiple-purpose thermal insulation. Material is rigid, closed-cell, thermally stable foam or urethane-modified isocyanate. Made by reacting polyol mixture with polymeric diphenyl methane disocyanate in presence of catalyst and flurocarbon blowing agent. Properties customized for particular application by adjusting proportions of ingredients in polyol mixture.