43 research outputs found
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Estimation of ionospheric reflection height using long wave propagation
Phase height measurements of low frequency radio waves are used to study the long-term variability of the mesosphere over Europe. Phase height measurements use a characteristic pattern in field strength registration of radio waves interpreted as phase relations between sky wave and surface wave to obtain the apparent height of the reflection point, the Standard Phase Height (SPH). Based on this SPH-method a homogenized daily series was generated since 1959 at Kühlungsborn. Improvements of the measuring method show that the signal is significantly influenced by lower atmospheric layers. Mesospheric reflection is not the exclusive source of the measured behavior. Tropospheric influence can not be neglected. Taking this into account one has to conclude that the strong coherency of the SPH data to mesospheric heights is not as significant as previously assumed. © Author(s) 2019
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Distortion of meteor count rates due to cosmic radio noise and atmospheric particularities
The determination of the meteoroid flux is still a scientifically challenging task. This paper focusses on the impact of extraterrestrial noise sources as well as atmospheric phenomena on the observation of specular meteor echoes. The effect of cosmic radio noise on the meteor detection process is estimated by computing the relative difference between radio loud and radio quiet areas and comparing the monthly averaged meteor flux for fixed signal-to-noise ratios or fixed electron line density measurements. Related to the cosmic radio noise is the influence of D-layer absorption or interference with sporadic E-layers, which can lead to apparent day-to-day variation of the meteor flux of 15-20%. © 2010 Author(s)
Distortion of meteor count rates due to cosmic radio noise and atmospheric particularities
The determination of the meteoroid flux is still a scientifically challenging
task. This paper focusses on the impact of extraterrestrial noise sources as
well as atmospheric phenomena on the observation of specular meteor echoes.
The effect of cosmic radio noise on the meteor detection process is estimated
by computing the relative difference between radio loud and radio quiet areas
and comparing the monthly averaged meteor flux for fixed signal-to-noise
ratios or fixed electron line density measurements. Related to the cosmic
radio noise is the influence of D-layer absorption or interference with
sporadic E-layers, which can lead to apparent day-to-day variation of the
meteor flux of 15–20%
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Long-term variations of the mesospheric wind field at mid-latitudes
Continuous MF radar observations at the station Juliusruh (54.6° N; 13.4° E) have been analysed for the time interval between 1990 and 2005, to obtain information about solar activity-induced variations, as well as long-term trends in the mesospheric wind field. Using monthly median values of the zonal and the meridional prevailing wind components, as well as of the amplitude of the semidiurnal tide, regression analyses have been carried out with a dependence on solar activity and time. The solar activity causes a significant amplification of the zonal winds during summer (increasing easterly winds) and winter (increasing westerly winds). The meridional wind component is positively correlated with the solar activity during summer but during winter the correlation is very small and non significant. Also, the solar influence upon the amplitude of the semidiurnal tidal component is relatively small (in dependence on height partly positive and partly negative) and mostly non-significant.
The derived trends in the zonal wind component during summer are below an altitude of about 83 km negative and above this height positive. During the winter months the trends are nearly opposite compared with the trends in summer (transition height near 86 km). The trends in the meridional wind components are below about 85 km positive in summer (significant) and near zero (nonsignificant) in winter; above this height during both seasons negative trends have been detected. The trends in the semidiurnal tidal amplitude are at all heights positive, but only partly significant.
The detected trends and solar cycle dependencies are compared with other experimental results and model calculations. There is no full agreement between the different results, probably caused by different measuring techniques and evaluation methods used. Also, different heights and observation periods investigated may contribute to the detected differences
Verbesserung der Osseointegration orthopädischer Implantate
In dieser Arbeit werden osteoinduktive Beschichtungsverfahren für orthopädische Implantate entwickelt. Für diese Untersuchungen werden zwei Implantatmodelle designt, die ganz bestimmte Charakteristika von orthopädischen Implantaten widerspiegeln. Die Charakterisierung der Modelle und der Beschichtung erfolgt durch experimentalphysikalische Untersuchungsmethoden. Die Beschreibung der Ossifikation wird durch die Auswertung von präklinischen In-vivo-Studien erbracht
Long-term variability of mean winds in the mesosphere and lower thermosphere at low latitudes
Long-term variations of monthly mean zonal and meridional winds in the Mesosphere and Lower Thermosphere (MLT) at low-latitudes are analyzed using four medium frequency (MF) radars and three meteor radars located in the Asia-Oceania region. Radar data taken at close-by latitudes are appended to construct long-term data sets. With this, we have long-term data from five distinct latitudes within ±22° (viz., 22°N, ∼9°N, 0–2°N, 6–7°S and 21°S). The data length varies at different latitudes and spans a maximum of two decades during 1990–2010. The zonal winds show semiannual oscillation (SAO) at all locations with westward (eastward) winds during equinoxes (solstices). The month height pattern of SAO is similar within ±9° and is different at ±22°. The westward winds in the March equinox were enhanced every two or three years during 1990–2002. We define this phenomenon as Mesospheric Quasi-Biennial Enhancement (MQBE). Such signature is not clear after 2002. The meridional winds show annual oscillation (AO), with northward and southward winds during the December and June solstices, respectively. However, the timing at which the wind direction changes does not coincide at all latitudes. The amplitude of the AO is enhanced after 2004 and 2008 at ∼9°N and ∼7°S, respectively. Orthogonal components of SAO and AO are detected with persistent phase relation, which suggests that the zonal and meridional winds are coupled. The meridional winds show long-term trends at latitudes of ∼9°N and ∼6–7°S, but not at other latitudes. The zonal winds do not show significant long-term trends.N. Venkateswara Rao, T. Tsuda, D. M. Riggin, S. Gurubaran, I. M. Reid, and R. A. Vincen
Early Detection and Monitoring of Cancer with the Anti-Malignin Antibody Test "
ABSTRACT: The serum anti-malignin antibody (AMA) test determines the antibody to malignin. a IO,OOO-Da peptide present in patients with a wide variety of cancers.l~ A total of 3315 double-blind tests demonstrated that AMA is a general transformation antibody, elevated in active no.nterminal cancer, regardless of the site or tissue type, with sensitivity and specificity of95% on the flTst determination and >99% on repeat determinations. - 9 Data have not however been published yet that indicate whether, in daily clinical practice, the AMA test provides accurate prospective and predictive information. Fony-two physicians from II states, who ordered the AMA test, performed blind, report here on their results on 208 determinations in the first consecutive 181 patients and controls. Used in monitoring treatment in 56 patients, the test predicted or agreed 94.1 % overall with the clinical status. Used in early detection in 125 patients and controls, of which 118 now have confirmed diagnoses. AMA was elevated in 21, all of whom were proven to have cancer; AMA was normal in 97, none of whom had cancer. Transient elevated AMA occurred in 3%, followed by normal values. Seven patients with still uncertain diagnosis who have had elevated AMA on repeated tests for I year or longer include six who are symptomatic, and three whose families have a high frequency of cancer. The conditions of these 7 may include undetected cancer because of the 118 with now certain diagnosis the AMA test predicted all correctly. From our experience, the AMA test should be used together with other routine procedures whenever signs and symptoms suggest cancer to facilitate early detection