382 research outputs found
Continuous Lyman-alpha generation by four-wave mixing in mercury for laser-cooling of antihydrogen
Cooling antihydrogen atoms is important for future experiments both to test
the fundamental CPT symmetry by high-resolution laser spectroscopy and also to
measure the gravitational acceleration of antimatter. Laser-cooling of
antihydrogen can be done on the strong 1S-2P transition at the wavelength of
Lyman-alpha (121.6nm). A continuous-wave laser at the Lyman-alpha wavelength
based on solid-state fundamental lasers is described. By using a two-photon and
a near one photon resonance a scan across the whole phasematching curve of the
four-wave mixing process is possible. Furthermore the influence of the beam
profile of one fundamental beam on the four-wave mixing process is studied.Comment: 4 pages, 4 figure
Connecting Angular Momentum and Galactic Dynamics: The complex Interplay between Spin, Mass, and Morphology
The evolution and distribution of the angular momentum of dark matter (DM)
halos have been discussed in several studies over the past decades. In
particular, the idea arose that angular momentum conservation should allow to
infer the total angular momentum of the entire DM halo from measuring the
angular momentum of the baryonic component, which is populating the center of
the halo, especially for disk galaxies. To test this idea and to understand the
connection between the angular momentum of the DM halo and its galaxy, we use
the Magneticum simulations. We successfully produce populations of spheroidal
and disk galaxies self-consistently. Thus, we are able to study the dependence
of galactic properties on their morphology. We find that (1) the specific
angular momentum of stars in disk and spheroidal galaxies as a function of
their stellar mass compares well with observational results; (2) the specific
angular momentum of the stars in disk galaxies is slightly smaller compared to
the specific angular momentum of the cold gas, in good agreement with
observations; (3) simulations including the baryonic component show a dichotomy
in the specific stellar angular momentum distribution when splitting the
galaxies according to their morphological type (this dichotomy can also be seen
in the spin parameter, where disk galaxies populate halos with slightly larger
spin compared to spheroidal galaxies); (4) disk galaxies preferentially
populate halos in which the angular momentum vector of the DM component in the
central part shows a better alignment to the angular momentum vector of the
entire halo; and (5) the specific angular momentum of the cold gas in disk
galaxies is approximately 40 percent smaller than the specific angular momentum
of the total DM halo and shows a significant scatter.Comment: 25 pages, accepted by ApJ, www.magneticum.or
High power, continuous-wave, single frequency fiber amplifier at 1091 nm and frequency doubling to 545.5 nm
We present a high power single-frequency ytterbium fiber amplifier system
with an output power of 30 W at 1091 nm. The amplifier system consists of two
stages, a preamplifier stage in which amplified spontaneous emission is
efficiently suppressed (>40 dB) and a high power amplifier with an efficiency
of 52 %. Two different approaches of frequency doubling are compared. We
achieve 8.6 W at 545.5 nm by single-pass frequency doubling in a MgO-doped
periodically poled stoichiometric LiTaO3 and up to 19.3 W at 545.5 nm by
frequency doubling with a lithium-triborate (LBO) crystal in an external
enhancement cavity
The use of shape-selective stationary phases in GC. Part 1: Cyclodextrin phases
ABSTRACT -Cyclodextrin phases are one of the most interesting geometry selective stationary phase in GC. 'beyare outstanding in their ability to separate isomeric and enantiomeric compounds. Two examples of the separation of cyclic compounds on cyclodextrins are given. The combination of chiral and achiral phases in series coupled columns is a useful tool for complicate separation and identification problems
Identification of extremely GC-rich micro RNAs for RT-qPCR data normalization in human plasma
We aimed at extending the repertoire of high-quality miRNA normalizers for reverse transcription-quantitative PCR (RT-qPCR) of human plasma with special emphasis on the extremely guanine-cytosine-rich portion of the miRNome. For high-throughput selection of stable candidates, microarray technology was preferred over small-RNA sequencing (sRNA-seq) since the latter underrepresented miRNAs with a guanine-cytosine (GC) content of at least 75% (p = 0.0002, n = 2). miRNA abundances measured on the microarray were ranked for consistency and uniformity using nine normalization approaches. The eleven most stable sequences included miRNAs of moderate, but also extreme GC content (45%–65%: miR-320d, miR-425-5p, miR-185-5p, miR-486-5p; 80%–95%: miR-1915-3p, miR-3656-5p, miR-3665-5p, miR-3960-5p, miR-4488-5p, miR-4497 and miR-4787-5p). In contrast, the seven extremely GC-rich miRNAs were not found in the two plasma miRNomes screened by sRNA-seq. Stem-loop RT-qPCR was employed for stability verification in 32 plasma samples of healthy male Caucasians (age range: 18–55 years). The lowest inter-individual variance of miRNA abundance was determined for miR-3665 and miR-1915-3p [coefficient of variation (CV) values: 0.08 and 0.50, respectively]. The eight most stable sequences included four extremely GC-rich miRNAs (miR-1915-3p, miR-3665, miR-4787-5p and miR-4497). The best-performing duo normalization factor (NF) for the condition of human plasma, miR-320d and miR-4787-5p, also included a GC-extreme miRNA. In summary, the identification of extremely guanine-cytosine-rich plasma normalizers will help to increase accuracy of PCR-based miRNA quantification, thus raise the potential that miRNAs become markers for psychological stress reactions or early and precise diagnosis of clinical phenotypes. The novel miRNAs might also be useful for orthologous contexts considering their conservation in related animal genomes
Element Mapping and Biomarker Analyses in an Early Byzantine City (CariÄŤin Grad, Serbia)
Soil analyses have a high potential to contribute to the investigation of daily life in ancient settlements. They can help to locate areas of food production, areas of waste disposal, latrines, stables and further functional areas. However, the applicability of these analyses is still restricted by a limited number of studies and a limited knowledge of their validity. In a multi-disciplinary project investigating the daily life in an early byzantine city (Caričin Grad), a multi-element-mapping and biomarker analyses were performed. The study focused on a comparison of the soil data with the data from other disciplines. The Caričin Grad Caričin Grad site in southern Serbia offered excellent conditions for this methodological study. It is supposed to be identical to Iustiniana Prima, an administrative center founded by the emperor Justinian. The period of occupation covered less than 90 years from circa 530 to 615 AD. The site remained undisturbed from later settlement encroachments. Therefore, it allows a rare archaeological ’snapshot’ of a short period of very intensive use. By analyses of the amounts of total organic carbon, total phosphorus and further elements (aqua-regia extraction), it was possible to divide different functional areas within the city. Element ratios and biomarkers including faecal steroids were used to get information on the specific use of the functional areas as well as on animal husbandry within the settlement. Data of soil analyses were compared and correlated with data that were obtained by consequent single point measurement and examination of the archaeological remains, 3D photography of the structures as well as archaeobotanical and archaeozoological analyses
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A semiconductor laser system for the production of antihydrogen
Laser-controlled charge exchange is a promising method for producing cold antihydrogen. Caesium atoms in Rydberg states collide with positrons and create positronium. These positronium atoms then interact with antiprotons, forming antihydrogen. Laser excitation of the caesium atoms is essential to increase the cross section of the charge-exchange collisions. This method was demonstrated in 2004 by the ATRAP collaboration by using an available copper vapour laser. For a second generation of charge-exchange experiments we have designed a new semiconductor laser system that features several improvements compared to the copper vapour laser. We describe this new laser system and show the results from the excitation of caesium atoms to Rydberg states within the strong magnetic fields in the ATRAP apparatus
Positive expectations predict improved mental-health outcomes linked to psychedelic microdosing
Psychedelic microdosing describes the ingestion of near-threshold perceptible doses of classic psychedelic substances. Anecdotal reports and observational studies suggest that microdosing may promote positive mood and well-being, but recent placebo-controlled studies failed to fnd compelling evidence for this. The present study collected web-based mental health and related data using a prospective (before, during and after) design. Individuals planning a weekly microdosing regimen completed surveys at strategic timepoints, spanning a core four-week test period. Eightyone participants completed the primary study endpoint. Results revealed increased self-reported psychological well-being, emotional stability and reductions in state anxiety and depressive symptoms at the four-week primary endpoint, plus increases in psychological resilience, social connectedness, agreeableness, nature relatedness and aspects of psychological fexibility. However, positive expectancy scores at baseline predicted subsequent improvements in well-being, suggestive of a signifcant placebo response. This study highlights a role for positive expectancy in predicting positive outcomes following psychedelic microdosing and cautions against zealous inferences on its putative therapeutic value
Antitumor activity of an Artemisia annua herbal preparation and identification of active ingredients
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