957 research outputs found
Ein Blick in die Blase—der Mensch dahinter
Zusammenfassung: Der Blick ins Innere des Menschen ist ein alter Wunsch in der Medizin. Die Entwicklung der Zystoskopie ist den dafür Interessierten bekannt. Nachfolgend steht diese Untersuchung nicht im Zentrum des Blickpunktes, sondern die Menschen, die dahinter stehen, die ihre Energien und ihre Phantasie einsetzen, um das einmal Erreichte zu verbessern. Dabei kommt man nicht darum herum, über Menschliches—Allzumenschliches—zu berichte
Histomorphological changes after neodymium: YAG laser-coagulation of the human prostate with the Side Focus fiber: Effect of power setting and time
The objective of our study was to determine optimal treatment parameters and appropriate methods of examination for neodymium:yttrium-aluminum-garnet (Nd:YAG) high-power laser coagulation of the human prostate in relation to power setting and time. Transurethral free-beam laser coagulation was performed with the Side-Focus side-firing laser fiber in ten patients prior to planned radical surgery, of whom six underwent transperitoneal laparoscopic lymphadenectomy and laser coagulation 4-9 days prior to open surgery. Depth and volume of coagulated prostatic tissue were measured at power setting/time combinations of 40 W/90 s and 60 W/60 s, respectively, while holding total energy delivery constant. Microscopic examination in the early phase showed that epithelial cells had become loose from the basal-cell membrane. By 4-9 days there was evidence of conspicuous squamous epithelial metaplasia with a high proliferation rate as a sign of reepithelialization. Using the Side Focus side-firing laser fiber, both treatment modalities showed comparable volume coagulation. In contrast there was a significant difference between those prostates removed at 4-9 days and those removed at 60-210 min after laser coagulation. We conclude that laser-induced changes in the human prostate are conclusively discernible only after 4 day
CO2 content beneath northern Iceland and the variability of mantle carbon
Primitive basalt melt inclusions from Borgarhraun, northern Iceland, display large correlated variations in CO2 and non-volatile incompatible trace elements (ITEs) such as Nb, Th, Rb, and Ba. The average CO2/ITE ratios of the Borgarhraun melt inclusion population are precisely determined (e.g., CO2/Nb = 391 ± 16; 2M, n = 161). These data, along with published data on five other populations of undegassed MORB glasses and melt inclusions, demonstrate that upper mantle CO2/Ba and CO2/Rb are nearly homogenous, while CO2/Nb and CO2/Th are broadly correlated with long-term indices of mantle heterogeneity reflected in Nd isotopes (143Nd/144Nd) in five out of the six regions of the upper mantle examined thus far. Our results suggest that heterogeneous carbon contents of the upper mantle are long-lived features, and that average carbon abundances of the mantle sources of Atlantic mid-ocean ridge basalts (MORB) are higher by a factor of two than those of Pacific MORB. This observation is correlated with a similar distinction in water contents (Michael, 1995) and trace elements characteristic of subduction fluids (Ba, Rb; Arevalo and McDonough, 2010). We suggest that the upper mantle beneath the younger Atlantic Ocean basin contains components of hydrated and carbonated subduction-modified mantle from prior episodes of Iapetus subduction that were entrained and mixed into the upper mantle during opening of the Atlantic Ocean basin.Maclennan is supported by Natural Environment Research Council grant NE/M000427/1. This research was supported by the Carnegie Institution of Washington and is a contribution to the Deep Carbon Observatory
Direct health costs of environmental tobacco smoke exposure and indirect health benefits due to smoking ban introduction
Background: Introducing comprehensive smoke-free policies to public places is expected to reduce health costs. This includes prevented health damages by avoiding environmental tobacco smoke (ETS) exposure as well as indirect health benefits from reduced tobacco consumption. Methods: The aim of this study was to estimate direct health costs of ETS exposure in public places and indirect health benefits from reduced tobacco consumption. We calculated attributable hospital days and years of life lost (YLL), based on the observed passive smoking and disease rates in Switzerland. The exposure-response associations of all relevant health outcomes were derived by meta-analysis from prospective cohort studies in order to calculate the direct health costs. To assess the indirect health benefits, a meta-analysis of smoking ban studies on hospital admissions for acute myocardial infarction was conducted. Results: ETS exposure in public places in Switzerland causes 32 000 preventable hospital days (95% CI: 10 000-61 000), 3000 YLL (95% CI: 1000-5000), corresponding to health costs of 330 Mio CHF. The number of hospital days for ischaemic heart disease attributable to passive smoking is much larger if derived from smoking ban studies (41 000) than from prospective cohort studies (3200), resulting in additional health costs of 89 Mio CHF, which are attributed to the indirect health benefits of a smoking ban introduction. Conclusion: The example of smoking ban studies on ischaemic heart disease hospitalization rates suggests that total health costs that can be prevented with smoking bans are considerably larger than the costs arising from the direct health impact of ETS exposure in public place
Spatiotemporal Amplitude and Phase Retrieval of Bessel-X pulses using a Hartmann-Shack Sensor
We propose a new experimental technique, which allows for a complete
characterization of ultrashort optical pulses both in space and in time.
Combining the well-known Frequency-Resolved-Optical-Gating technique for the
retrieval of the temporal profile of the pulse with a measurement of the
near-field made with an Hartmann-Shack sensor, we are able to retrieve the
spatiotemporal amplitude and phase profile of a Bessel-X pulse. By following
the pulse evolution along the propagation direction we highlight the
superluminal propagation of the pulse peak
Radioactive Probes of the Supernova-Contaminated Solar Nebula: Evidence that the Sun was Born in a Cluster
We construct a simple model for radioisotopic enrichment of the protosolar
nebula by injection from a nearby supernova, based on the inverse square law
for ejecta dispersion. We find that the presolar radioisotopes abundances
(i.e., in solar masses) demand a nearby supernova: its distance can be no
larger than 66 times the size of the protosolar nebula, at a 90% confidence
level, assuming 1 solar mass of protosolar material. The relevant size of the
nebula depends on its state of evolution at the time of radioactivity
injection. In one scenario, a collection of low-mass stars, including our sun,
formed in a group or cluster with an intermediate- to high-mass star that ended
its life as a supernova while our sun was still a protostar, a starless core,
or perhaps a diffuse cloud. Using recent observations of protostars to estimate
the size of the protosolar nebula constrains the distance of the supernova at
0.02 to 1.6 pc. The supernova distance limit is consistent with the scales of
low-mass stars formation around one or more massive stars, but it is closer
than expected were the sun formed in an isolated, solitary state. Consequently,
if any presolar radioactivities originated via supernova injection, we must
conclude that our sun was a member of such a group or cluster that has since
dispersed, and thus that solar system formation should be understood in this
context. In addition, we show that the timescale from explosion to the creation
of small bodies was on the order of 1.8 Myr (formal 90% confidence range of 0
to 2.2 Myr), and thus the temporal choreography from supernova ejecta to
meteorites is important. Finally, we can not distinguish between progenitor
masses from 15 to 25 solar masses in the nucleosynthesis models; however, the
20 solar mass model is somewhat preferred.Comment: ApJ accepted, 19 pages, 3 figure
Pb isotopic variability in melt inclusions from the EMI–EMII–HIMU mantle end-members and the role of the oceanic lithosphere
Melt inclusions from four individual lava samples representing the HIMU (Mangaia Island), EMI (Pitcairn Island) and EMII (Tahaa Island) end member components, have heterogeneous Pb isotopic composition larger than that defined by the erupted lavas in each island. The broad linear trend in ^(207)Pb/^(206)Pb–^(208)Pb/^(206)Pb space produced by the melt inclusions from Mangaia, Tahaa and fPitcairn samples reproduces the entire trend defined by the Austral chain, the Society islands and the Pitcairn island and seamount groups. The inclusions preserve a record of melt composition of far greater isotopic diversity than that sampled in whole rock basalts. These results can be explained by mixing of a common depleted component with the HIMU, EMI and EMII lavas, respectively. We favor a model that considers the oceanic lithosphere to be that common component. We suggest that the Pb isotopic compositions of the melt inclusions reflect wall rock reaction of HIMU, EMI and EMII melts during their percolation through the oceanic lithosphere. Under these conditions, the localized rapid crystallization of olivine from primitive basalt near the reaction zone would allow the entrapment of melt inclusions with different isotopic composition
Extremely high He isotope ratios in MORB-source mantle from the proto-Iceland plume
The high <sup>3</sup>He/<sup>4</sup>He ratio of volcanic rocks thought to be derived from mantle plumes is taken as evidence for the existence of a mantle reservoir that has remained largely undegassed since the Earth's accretion. The helium isotope composition of this reservoir places constraints on the origin of volatiles within the Earth and on the evolution and structure of the Earth's mantle. Here we show that olivine phenocrysts in picritic basalts presumably derived from the proto-Iceland plume at Baffin Island, Canada, have the highest magmatic <sup>3</sup>He/<sup>4</sup>He ratios yet recorded. A strong correlation between <sup>3</sup>He/<sup>4</sup>He and <sup>87</sup>Sr/<sup>86</sup>Sr, <sup>143</sup>Nd/<sup>144</sup>Nd and trace element ratios demonstrate that the <sup>3</sup>He-rich end-member is present in basalts that are derived from large-volume melts of depleted upper-mantle rocks. This reservoir is consistent with the recharging of depleted upper-mantle rocks by small volumes of primordial volatile-rich lower-mantle material at a thermal boundary layer between convectively isolated reservoirs. The highest <sup>3</sup>He/<sup>4</sup>He basalts from Hawaii and Iceland plot on the observed mixing trend. This indicates that a <sup>3</sup>He-recharged depleted mantle (HRDM) reservoir may be the principal source of high <sup>3</sup>He/<sup>4</sup>He in mantle plumes, and may explain why the helium concentration of the 'plume' component in ocean island basalts is lower than that predicted for a two-layer, steady-state model of mantle structure
Empirical comparison of high gradient achievement for different metals in DC and pulsed mode
For the SwissFEL project, an advanced high gradient low emittance gun is
under development. Reliable operation with an electric field, preferably above
125 MV/m at a 4 mm gap, in the presence of an UV laser beam, has to be achieved
in a diode configuration in order to minimize the emittance dilution due to
space charge effects. In the first phase, a DC breakdown test stand was used to
test different metals with different preparation methods at voltages up to 100
kV. In addition high gradient stability tests were also carried out over
several days in order to prove reliable spark-free operation with a minimum
dark current. In the second phase, electrodes with selected materials were
installed in the 250 ns FWHM, 500 kV electron gun and tested for high gradient
breakdown and for quantum efficiency using an ultra-violet laser.Comment: 25 pages, 13 figures, 5 tables. Follow up from FEL 2008 conference
(Geyongju Korea 2008) New Title in JVST A (2010) : Vacuum breakdown limit and
quantum efficiency obtained for various technical metals using DC and pulsed
voltage source
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