Alacsony D-vitamin-szint a Semmelweis Egyetem betegei körében

Even in developed countries the prevalence of subjects with suboptimal vitamin D levels is high. The aim of this retrospective data analysis was to evaluate the prevalence of severe and moderate vitamin D deficiencies (defined as vitamin D levels<15 ng/ml and 15-30 ng/ml, respectively) among patients evaluated at Semmelweis University during a period between April, 2009 and March, 2010. Methods and results: The average vitamin D level of 5808 subjects (3936 women and 1872 men) was 25.5 +/- 10.9 ng/ml. The prevalence of moderate and severe vitamin D deficiency in whole population was 72% and 12%, respectively. Higher than normal vitamin D levels were measured in 0.8% of subjects. Female gender, older age and winter season were independent risk factors for vitamin D deficiency. Vitamin D levels were measured repeatedly in 1307 subjects. Interestingly, vitamin D levels measured later were lower compared to those measured at the first time (27.07+/-13.2 vs. 25.9+/-9.11 ng/ml, p<0.001). The prevalence of severe and moderate vitamin D deficiency was 8.1 and 71.5 per cent when vitamin D levels were measured at the second time. Of the 110 patients with severe vitamin D deficiency measured repeatedly only 11 patients (10%) presented with normal vitamin D levels at the second time. Conclusions: These data indicate that severe and moderate vitamin D deficiencies are common in patients evaluated at Semmelweis University. Repeated measurements of vitamin D levels raise the notion that the efficacy of supplementation used for correction of vitamin D levels is not optimal

Global circuit response to the 11-year solar cycle: Changes in source or in medium?

© International Conference on Atmospheric Electricity, ICAE 2014 Modifications to both the DC and AC global circuits are considered on both short time scales and on the 11-year solar cycle time scale. New long-term records of Schumann resonances are considered as documentation of the AC global circuit. In most cases, changes in the medium of the global circuit provide a better qualitative explanation than intrinsic source changes (i.e., lightning and electrified clouds) for the variations in the global circuit. Further work is needed with the quantitative details

Schumann Resonance spectral characteristics: A useful tool to study Transient Luminous Events (TLEs) on a global scale

© International Conference on Atmospheric Electricity, ICAE 2014 The background Schumann Resonance (SR) spectra require a natural stabilization period of ~10-12 minutes for the three modal parameters, namely, the frequency, intensity and Q-factor to be derived from Lorentzian fitting. Before the spectra are computed and the fitting process is initiated, the raw time series data need to be properly filtered for local cultural noise, narrow band interference as well as large transients in the form of global Q-bursts. Mushtak and Williams [2009] describe an effective technique named as Isolated Lorentzian (I-LOR), in which, the contribution from local cultural and various other noises are minimized to a great extent, and enabling the problem of inter-modal interference to be more effectively addressed in the SR background spectra. An automated technique based on median filtering of time series data and the rejection of events exceeding 16 core standard deviations (CSD) (where \u27core\u27 pertains to the central portion of the spectral power content ) from the average of the period of interest has also been developed by Mushtak et al. [2012]. This cleaning of data before obtaining the modal parameters is essential for work related to the background SR, for example, finding the source strength of tropical \u27chimney\u27 regions by inversion of multi-station data. The methodology used for removing the effect of Q-bursts from background SR spectra could also be used to search for big sprite-producing positive lightning flashes in mesoscale convective systems worldwide. These special lightning flashes are known to have greater contribution in the ELF range (below 1 kHz) compared to negative CG strikes [Cummer 2006]. The global distributions of these Q-bursts have been studied by Huang et al., [1999] and Hobara et al. [2006] by wave impedance methods from single station ELF measurements at Rhode Island, USA. The present work aims to demonstrate the effect of Q-bursts on SR spectra using GPS time-stamped observation of TLEs and average energy data from the VLF World Wide Lightning Location Network (WWLLN). It is observed that the Q-bursts selected for the present work do alias with the background spectra over a five second period, through the amplitudes of these Q-bursts are far below the 16 CSD limit so that they do not strongly alias the background spectra of 10-12 minute duration. The extent of this aliasing is yet to be investigated thoroughly. It is expected that the spectral ELF methodology could be used effectively to detect TLEs globally with a small number of networked stations, especially during daylight conditions, when optical measurements of sprites are not possible

Aliasing of the Schumann resonance background signal by sprite-associated Q-bursts

The Earth's naturally occurring Schumann resonances (SR) are composed of a quasi-continuous background component and a larger-amplitude, short-duration transient component, otherwise called ‘Q-burst’ (Ogawa et al., 1967). Sprites in the mesosphere are also known to accompany the energetic positive ground flashes that launch the Q-bursts (Boccippio et al., 1995). Spectra of the background Schumann Resonances (SR) require a natural stabilization period of ~10–12 min for the three conspicuous modal parameters to be derived from Lorentzian fitting. Before the spectra are computed and the fitting process is initiated, the raw time series data need to be properly filtered for local cultural noise, narrow band interference as well as for large transients in the form of global Q-bursts. Mushtak and Williams (2009) describe an effective technique called Isolated Lorentzian (I-LOR), in which, the contributions from local cultural and various other noises are minimized to a great extent. An automated technique based on median filtering of time series data has been developed. These special lightning flashes are known to have greater contribution in the ELF range (below 1 kHz) compared to general negative CG strikes (Huang et al., 1999; Cummer et al., 2006). The global distributions of these Q-bursts have been studied by Huang et al. (1999) Rhode Island, USA by wave impedance methods from single station ELF measurements at Rhode Island, USA and from Japan Hobara et al. (2006). The present work aims to demonstrate the effect of Q- bursts on SR background spectra using GPS time-stamped observation of TLEs. It is observed that the Q-bursts selected for the present work do alias the background spectra over a 5-s period, though the amplitudes of these Q- bursts are far below the background threshold of 16 Core Standard Deviation (CSD) so that they do not strongly alias the background spectra of 10–12 min duration. The examination of one exceptional Q-burst shows that appreciable spectral aliasing can occur even when 12-min spectral integrations are considered. The statistical result shows that for a 12-min spectrum, events above 16 CSD are capable of producing significant frequency aliasing of the modal frequencies, although the intensity aliasing might have a negligible effect unless the events are exceptionally large (~200 CSD). The spectral CSD methodology may be used to extract the time of arrival of the Q-burst transients. This methodology may be combined with a hyperbolic ranging, thus becoming an effective tool to detect TLEs globally with a modest number of networked observational stations.Peer ReviewedPostprint (published version

Schumann Resonance spectral characteristics: a useful tool to study Transient Luminous Events (TLEs) on global scale

Postprint (published version

Rizeni sluzeb informatiky v podminakch outsourcingu.

Available from STL, Prague, CZ / NTK - National Technical LibrarySIGLECZCzech Republi

Schupy : a python package for modeling and analyzing Schumann resonances

Schupy is an open-source python package aimed at modeling and analyzing Schumann resonances (SRs), the global electromagnetic resonances of the Earth-ionosphere cavity resonator in the lowest part of the extremely low frequency band (<100 Hz). Its very-first function forward_tdte applies the solution of the 2-D telegraph-equation introduced recently by Prácser et al. (2019) for a uniform cavity and is able to determine theoretical SR spectra for arbitrary source-observer configurations. It can be applied for modeling both the amplitude and phase of extraordinarily large SR-transients and the power spectral density of SRs excited by incoherently superimposed lightning strokes within an extended source region. In this contribution, test results of planned new functionalities of the package are presented. A new function aims at removing sections of the measured data, e.g. Q-bursts, which bias spectral characteristics of natural “background” electromagnetic noise. This way, PSD will be calculated from a sanitized time series. Other new functions are introduced for determining the spectral parameters (amplitude/intensity, frequency, Q-factor) of SR modes using different approaches, i.e., symmetrical and asymmetrical Lorentzian fitting, complex demodulation, and the weighted average method. We would like to encourage the community to join our project in developing open-source modeling and signal analyzing capacities for SR research as part of the schupy package

Aliasing of the Schumann resonance background signal by sprite-associated Q-bursts

The Earth's naturally occurring Schumann resonances (SR) are composed of a quasi-continuous background component and a larger-amplitude, short-duration transient component, otherwise called ‘Q-burst’ (Ogawa et al., 1967). Sprites in the mesosphere are also known to accompany the energetic positive ground flashes that launch the Q-bursts (Boccippio et al., 1995). Spectra of the background Schumann Resonances (SR) require a natural stabilization period of ~10–12 min for the three conspicuous modal parameters to be derived from Lorentzian fitting. Before the spectra are computed and the fitting process is initiated, the raw time series data need to be properly filtered for local cultural noise, narrow band interference as well as for large transients in the form of global Q-bursts. Mushtak and Williams (2009) describe an effective technique called Isolated Lorentzian (I-LOR), in which, the contributions from local cultural and various other noises are minimized to a great extent. An automated technique based on median filtering of time series data has been developed. These special lightning flashes are known to have greater contribution in the ELF range (below 1 kHz) compared to general negative CG strikes (Huang et al., 1999; Cummer et al., 2006). The global distributions of these Q-bursts have been studied by Huang et al. (1999) Rhode Island, USA by wave impedance methods from single station ELF measurements at Rhode Island, USA and from Japan Hobara et al. (2006). The present work aims to demonstrate the effect of Q- bursts on SR background spectra using GPS time-stamped observation of TLEs. It is observed that the Q-bursts selected for the present work do alias the background spectra over a 5-s period, though the amplitudes of these Q- bursts are far below the background threshold of 16 Core Standard Deviation (CSD) so that they do not strongly alias the background spectra of 10–12 min duration. The examination of one exceptional Q-burst shows that appreciable spectral aliasing can occur even when 12-min spectral integrations are considered. The statistical result shows that for a 12-min spectrum, events above 16 CSD are capable of producing significant frequency aliasing of the modal frequencies, although the intensity aliasing might have a negligible effect unless the events are exceptionally large (~200 CSD). The spectral CSD methodology may be used to extract the time of arrival of the Q-burst transients. This methodology may be combined with a hyperbolic ranging, thus becoming an effective tool to detect TLEs globally with a modest number of networked observational stations.Peer Reviewe