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Search Results: 1 - 10 of 202079 matches for " P. Hoffmann "
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Marijuana Use and Depressive Symptoms among Young People: Examining Unidirectional and Bidirectional Effects  [PDF]
John P. Hoffmann
Health (Health) , 2018, DOI: 10.4236/health.2018.108080
Abstract: Research suggests that the prevalence of marijuana use and depression are increasing in the United States. Although it is not entirely clear what accounts for these coincident trends, several studies have shown that these two health concerns are associated among young people. This study assessed four hypotheses regarding the association between marijuana use and depression: 1) whether marijuana use affects subsequent symptoms of depression; 2) whether depressive symptoms affect subsequent marijuana use; 3) whether they are associated in a bidirectional (reciprocal) manner; and 4) whether the association between the two is confounded by stressful life events. Using eight years of longitudinal data from the Family Wellness and Health Study, a fixed-effects regression model provided empirical support for the first hypothesis only, but not for the others. Future research should explore in greater detail why marijuana use may have a causal impact on experiences with depression among young people.
Diagnose Prostatakarzinom: Ja - Therapie: Nein?
Gathmann P,Hoffmann E
Journal für Urologie und Urogyn?kologie , 2009,
Pitting corrosion in the wet section of the automotive exhaust systems
C. Hoffmann,P. Gümpel
Journal of Achievements in Materials and Manufacturing Engineering , 2009,
Abstract: Purpose: In the rear section of the automotive exhaust systems condensates bearing appreciable chloride ion concentrations and often low pH-values together with particles of electrochemical active soot can lead to pronounced pitting corrosion on the inner surfaces. For selection of an appropriate material that can enable cost-effective construction, the corrosion resistance of different candidate grades has to be rated.Design/methodology/approach: The different types of occurring corrosion, both general attack and pitting corrosion demands a combination of evaluation methods of the corrosion attack: mass loss measurements and the measure of the average depth of a certain number of pits with an optical 3D-Measuring System MicroCAD were used.Findings: The two methods for the evaluation of the corrosion attack provide the same ranking of the materials. Both methods are complementary to each other and together they provide a noticeable differentiation between some of the investigated materials.Research limitations/implications: The average depth of the pits gives no information about the entire rate of the corrosion attack, about the total number of the pits and their depth. In the future, research with the same optical 3D-Measuring System MicroCAD and new software will be carried out. This will form a structured analysis of the entire pits for the quantification of the corrosion.Practical implications: A higher quantification of the pitting corrosion leads to a better rating of the different stainless steel grades for using them in the wet section of the automotive exhaust systems.Originality/value: The evaluation of the pitting corrosion by means of the new measurement methods with the optical 3D-Measuring System MicroCAD is more accurate, work fast and is an obligatory complement of the previous methods of evaluation of the pitting corrosion: mass loss and the depth of the deepest pit.
Nichtmedikament se Therapie der arteriellen Hypertonie
Schmid P,Hoffmann P,Pokan R
Journal für Hypertonie , 2002,
Aspect génétique de l'abduction des membres ("splayleg") dans les lignées de porcs large white et piétrain et leurs croisements
JP Hoffmann, P Sellier, L Ollivier
Genetics Selection Evolution , 1980, DOI: 10.1186/1297-9686-12-4-422b
Trends in MLT region winds and planetary waves, Collm (52° N, 15° E)
Ch. Jacobi, P. Hoffmann,D. Kürschner
Annales Geophysicae (ANGEO) , 2008,
Abstract: Long-period oscillations in the period range 2–30 days, interpreted as planetary wave (PW) signatures, have been analysed using daily mesosphere/lower thermosphere wind measurements near 90 km over Collm (52° N, 15° E) in the time interval 1980–2005. Interannual and interdecadal variability of PW are found. Since the 1990s, a tendency for larger zonal amplitudes compared to meridional ones has been observed, i.e. some long-term trends are visible, which are positive in the zonal component, but negative in the meridional component. There is a tendency of the trend to be non-linear for waves with periods lower than 7 days, so that a climatic transition appears around 1990, with smaller changes before and after that time. A solar cycle effect on PW is weak, but there is a tendency for a positive correlation between solar flux and wave activity, if a time lag of PW activity with respect to the solar flux of about 2 years is taken into consideration.
Aspect génétique de l'abduction des membres ("splayleg") dans les lignées de porcs large white et piétrain et leurs croisements
Hoffmann JP,Sellier P,Ollivier L
Genetics Selection Evolution , 1980,
Errors in Measurement of Microwave Interferograms Using Antenna Matrix
J. Zela,K. Hoffmann,P. Hudec
Radioengineering , 2008,
Abstract: New antenna matrices for both scalar and vector measurement of microwave interferograms for the frequency 2.45 GHz were developed and used for an analysis of sources of measurement errors. Influence of mutual coupling between individual antennas in an antenna matrix on a measurement of microwave interferograms, particularly on a measurement of interferogram minimum values, was studied. Simulations and measurements of interferograms, proposal of a new calibration procedure and correction method are presented. Influence of differences in radiation patterns of individual antennas of an antenna matrix on a measurement of microwave interferograms was studied as well.
Geomagnetic control of polar mesosphere summer echoes
J. Bremer,P. Hoffmann,T. L. Hansen
Annales Geophysicae (ANGEO) , 2003,
Abstract: Using observations with the ALOMAR SOUSY radar near Andenes (69.3°N, 16.0°E) from 1994 until 1997 polar mesosphere summer echoes (PMSE) have been investigated in dependence on geomagnetic K indices derived at the Auroral Observatory Troms (69.66°N, 18.94°E). During night-time and morning hours a significant correlation between the signal-to-noise ratio (SNR) of the radar results and the geomagnetic K indices could be detected with a maximum correlation near midnight. The correlation becomes markedly smaller in the afternoon and early evening hours with a minimum near 17 UT. This diurnal variation is in reasonable agreement with riometer absorption at Ivalo (68.55°N, 27.28°E) and can be explained by the diurnal variation of ionization due to precipitating high energetic particles. Therefore, a part of the diurnal PMSE variation is caused by this particle precipitation. The variability of the solar EUV variation, however, has no significant influence on the PMSE during the observation period. Keywords: Ionosphere (auroral ionosphere) - Magnetospheric physics (energetic particles, precipitating) - Radio science (remote sensing)
Connections of the superior colliculus to shoulder muscles of the rat: a dual tracing study
M. Rothermel,K.-P. Hoffmann
Frontiers in Neuroanatomy , 2013, DOI: 10.3389/fnana.2013.00017
Abstract: Previous investigations indicate that the superior colliculus (SC) is involved in the initiation and execution of forelimb movements. In the present study we investigated the tectofugal, in particular the tecto-reticulo-spinal projections to the shoulder and arm muscles in the rat. We simultaneously retrogradely labeled the premotor neurons in the brainstem by injection of the pseudorabies virus PrV Bartha 614 into the m. rhomboideus minor and m. acromiodeltoideus, and anterogradely visualized the tectofugal projections by intracollicular injection of the tracer FITC dextrane. Our results demonstrate that the connection of the SC to the skeletal muscles of the forelimb is at least trisynaptic. This was confirmed by long survival times after virus injections into the muscles (98–101 h) after which numerous neurons in the deep layers of the SC were labeled. Transsynaptically retrogradely labeled brainstem neurons connected disynaptically to the injected muscles with adjacent tectal terminals were predominantly located in the gigantocellular nuclear complex of the reticular formation. In addition, putative relay neurons were found in the caudal part of the pontine reticular nucleus. Both tectal projections to the nucleus gigantocellularis and the pontine reticular nucleus were bilateral but ipsilaterally biased. We suggest this projection to be involved in more global functions in motivated behavior like general arousal allowing fast voluntary motor activity.
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