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Search Results: 1 - 10 of 87 matches for " Klapp "
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Chlamydienpr vention - auch für Jungen?
Klapp C
Blickpunkt der Mann , 2007,
Abstract: In Deutschland infizieren sich j hrlich gesch tzte 300.000 400.000 vorwiegend junge Menschen mit Chlamydia trachomatis (Serogruppe D K). Mit ihren h ufigen Komplikationen gilt diese sexuell übertragbare Infektion (STI) als Hauptverursacher infektionsbedingter Sterilit t bislang fast nur bei Frauen. Inzwischen mehren sich Hinweise, da M nner durch Chlamydien nicht nur oft übertr ger, sondern auch unmittelbar in ihrer Reproduktionsf higkeit beeintr chtigt sind. Mangelnde Kenntnis, frühe sexuelle Aktivit t und unzureichendes Verhütungsverhalten lassen vermuten, da hier eine "schleichende Epidemie" im Gange ist, deren Ausma aufgrund fehlender epidemiologischer Daten für Deutschland nicht bekannt ist. Daten aus Gro britannien, den Niederlanden und einigen skandinavischen L ndern mit Meldepflicht lassen auf einen besorgniserregenden Anstieg in den vergangenen Jahren schlie en. Unsere Pr valenzbeobachtung bei 18j hrigen M dchen in Berlin fand z. B. bei 10 % der meist symptomlosen 17j hrigen eine frische Infektion mit Chlamydia trachomatis (CT). Ohne rechtzeitige Therapie kann sich eine chronische, über Jahre persistierende Infektion entwickeln. Gleichzeitig ergab unsere Untersuchung, da fast 90 % noch nie etwas von CT und ihren m glichen Folgen erfahren hatten und da weniger als 20 % dieser Paare beim letzten Verkehr mit Kondomen geschützt waren. Ziel der wenigen einzelnen prim r- und sekund rpr ventiven Ma nahmen waren bislang vorwiegend junge Frauen, hier müssen breitangelegte Aufkl rungskampagnen starten, die auch Jungen und junge M nner mit einbeziehen, denn Pr vention ist hier einfach und wirkungsvoll, notwendige Komplikationsprophylaxe sinnvoll und notwendig. Kondome k nnen hier positiv besetzt werden, n mlich als Schutz der eigenen und gemeinsamen Fruchtbarkeit.
Dimensionality Effects in Dipolar Fluids: A Density Functional Theory Study  [PDF]
Remi Geiger, Sabine H. L. Klapp
Journal of Modern Physics (JMP) , 2013, DOI: 10.4236/jmp.2013.43A056
Abstract:
Using classical density functional theory (DFT) in a modified mean-field approximation we investigate the fluid phase behavior of quasi-two dimensional dipolar fluids confined to a plane. The particles carry three-dimensional dipole moments and interact via a combination of hard-sphere, van-der-Waals, and dipolar interactions. The DFT predicts complex phase behavior involving first- and second-order isotropic-to-ferroelectric transitions, where the ferroelectric ordering is characterized by global polarization within the plane. We compare this phase behavior, particularly the onset of ferroelectric ordering and the related tri-critical points, with corresponding three-dimensional systems, slab-like systems (with finite extension into the third direction), and true two-dimensional systems with two-dimensional dipole moments.
The final fate of very massive first stars
Klapp, J;Bahena, D;
Revista mexicana de física , 2008,
Abstract: a generation of stars which formed from primordial nearly pure h/he gas, the so-called first stars or population iii stars, must have existed since heavy elements can only be synthesized in the interior of the stars. these stars were responsible for the initial heavy elements enrichment of the intergalactic medium. in this work we analyze the possible outcome of the evolution of very massive population iii stars and whether their final fate can avoid the pair instability supernovae explosion. we have recently calculated the evolution and nucleosynthesis of mass losing very massive population iii stars during the hydrogen and helium burning phases, and proposed a new scenario for the first stars in the universe. according to this scenario, the first stars were born very massive, but evolve with mass loss, and its possible endpoint is a hypernovae stage. at low metallicity the effects on the presupernova structure depends on the initial mass and the mass loss rate during the main sequence evolution. presupernova stars of lower metallicity have different characteristics depending if they are galactic or pregalactic, and if they evolve without or with mass loss. when these stars evolve with mass loss, their convective core size increase and their helium- or carbon-oxygen core mass decreases. then, the stars could explode like hypernovae or supernovae.
The final fate of very massive first stars
J. Klapp,D. Bahena
Revista mexicana de física , 2008,
Abstract: Una primera generación de estrellas formada de gas primordial casi puro de H y He, las llamadas primeras estrellas o estrellas de Población III, debió haber existido ya que los elementos pesados solo pueden ser sintetizados en el interior de las estrellas. Estas estrellas fueron responsables del enriquecimiento inicial del medio intergaláctico en elementos pesados. En este trabajo, analizamos el posible desenlace de la evolución de estrellas muy masivas de la Población III y cuando, su destino final, puede evitar la explosión de supernova por inestabilidad de pares. Recientemente hemos calculado la evolución y nucleosíntesis de estrellas muy masivas de población III con pérdida de masa durante los quemados de hidrógeno y helio, y propuesto un nuevo escenario para las primeras estrellas del universo. De acuerdo a este escenario, las primeras estrellas nacieron muy masivas pero evolucionaron con perdida de masa terminando su vida como hipernovas. A baja metalicidad los efectos de la estructura presupernova depende de la masa inicial y de la tasa de perdida de masa durante la secuencia principal. Las estrellas de presupernova de baja metalicidad tienen diferentes características dependiendo de si son galácticas o pregalácticas y si evolucionan con o sin pérdida de masa. Cuando evolucionan con pérdida de masa, el tama o de su núcleo convectivo aumenta y las masas de sus nucleos de helio o de carbono-oxígeno disminuyen. Por consiguiente, estas estrellas podrían explotar como supernovas o hipernovas.
EPR of borax-alanine mixtures irradiated with thermal neutrons
S. Galindo,J. Klapp +
Revista mexicana de física , 2005,
Abstract: Se reporta la Resonancia Paramagnética Electrónica (EPR) de mezclas de alanina y borax irradiadas con neutrones. El objetivo de estos experimentos es establecer una técnica de dosimetría EPR para neutrones térmicos basada en el incremento de la se al de alanina debido al contenido de boro en las mezclas vía una reacción de captura neutrónica. Se presenta la respuesta de la se al como función del contenido de boro y del tama o de los cristalitos de las mezclas.
Arqueoastronomía y la traza urbana en Teotihuacan
Salvador Galindo,Jaime Klapp
Ciencia Ergo Sum , 2009,
Abstract: Al examinar la orientación de trazas urbanas a lo largo de México se puede observar una alineación particular al este de la dirección norte que coincide con la alineación de la antigua ciudad de Teotihuacan. Este trabajo recoge las distintas explicaciones surgidas sobre el origen de esta característica peculiar de Teotihuacan.
First Stars. I. Evolution without mass loss
D. Bahena,J. Klapp
Physics , 2010, DOI: 10.1007/s10509-010-0322-1
Abstract: The first generation of stars was formed from primordial gas. Numerical simulations suggest that the first stars were predominantly very massive, with typical masses M > 100 Mo. These stars were responsible for the reionization of the universe, the initial enrichment of the intergalactic medium with heavy elements, and other cosmological consequences. In this work, we study the structure of Zero Age Main Sequence stars for a wide mass and metallicity range and the evolution of 100, 150, 200, 250 and 300 Mo galactic and pregalactic Pop III very massive stars without mass loss, with metallicity Z=10E-6 and 10E-9, respectively. Using a stellar evolution code, a system of 10 equations together with boundary conditions are solved simultaneously. For the change of chemical composition, which determines the evolution of a star, a diffusion treatment for convection and semiconvection is used. A set of 30 nuclear reactions are solved simultaneously with the stellar structure and evolution equations. Several results on the main sequence, and during the hydrogen and helium burning phases, are described. Low metallicity massive stars are hotter and more compact and luminous than their metal enriched counterparts. Due to their high temperatures, pregalactic stars activate sooner the triple alpha reaction self-producing their own heavy elements. Both galactic and pregalactic stars are radiation pressure dominated and evolve below the Eddington luminosity limit with short lifetimes. The physical characteristics of the first stars have an important influence in predictions of the ionizing photon yields from the first luminous objects; also they develop large convective cores with important helium core masses which are important for explosion calculations.
Comparing Gluon to Quark Jets with DELPHI
Oliver Klapp,Patrick Langefeld
Physics , 1999,
Abstract: This is a summary of the latest results of the DELPHI Collaboration on the properties of identified quark and gluon jets. It covers the measurement of the fragmentation functions of gluons and quarks and their scaling violation behaviour as well as an analysis of the scale dependence of the multiplicities in gluon and quark jets. Further, a precision measurement of CA/CF from the multiplicities in symmetric three jet events is discussed.
Simulations of Colliding Uniform Density H2 Clouds  [PDF]
Guillermo Arreaga-García, Jaime Klapp, Julio Saucedo Morales
International Journal of Astronomy and Astrophysics (IJAA) , 2014, DOI: 10.4236/ijaa.2014.41018
Abstract: In this paper we present a set of numerical simulations designed to study the interaction process of HII molecular clouds. For the initial conditions we assume head-on and oblique collisions of binary identical clouds placedadjacent to one another, with their surfaces just in contact. The colliding initial clouds are uniform density molecular gas spheres with rigid body rotation. The cloud initial conditions are chosen to favor its gravitational collapse as an isolated system. To study the effect of the self-gravity of the cloud in the collision process, we consider several models in which the approaching speed of the colliding clouds increases from zero up to several times the initial sound speed of the barotropic gas. We present the outcome of these collision models for several values of the impact parameter b, which depends on
Dimensionality effects in dipolar fluids
R. Geiger,S. H. Klapp
Physics , 2010, DOI: 10.4236/jmp.2013.43A056
Abstract: Using classical density functional theory (DFT) in a modified mean-field approximation we investigate the fluid phase behavior of quasi-two dimensional dipolar fluids confined to a plane. The particles carry three-dimensional dipole moments and interact via a combination of hard-sphere, van-der-Waals, and dipolar interactions. The DFT predicts complex phase behavior involving first- and second-order isotropic-to-ferroelectric transitions, where the ferroelectric ordering is characterized by global polarization within the plane. We compare this phase behavior, particularly the onset of ferroelectric ordering and the related tricritical points, with corresponding three-dimensional systems, slab-like systems (with finite extension into the third direction), and true two-dimensional systems with two-dimensional dipole moments.
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