428 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
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
Element Mapping and Biomarker Analyses in an Early Byzantine City (Caričin 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
Convulsive status epilepticus management in adults and children: Report of the Working Group of the Polish Society of Epileptology
Introduction
The Working Group was established at the initiative of the General Board of the Polish Society of Epileptology (PSE) to develop an expert position on the treatment of convulsive status epilepticus (SE) in adults and children in Poland. Generalized convulsive SE is the most common form and also represents the greatest threat to life, highlighting the importance of the choice of appropriate therapeutic treatment.
Aim of guideline
We present the therapeutic options separately for treatment during the early preclinical (>5–30min), established (30–60min), and refractory (>60min) SE phases. This division is based on time and response to AEDs, and indicates a practical approach based on pathophysiological data.
Results
Benzodiazepines (BZD) are the first-line drugs. In cases of ineffective first-line treatment and persistence of the seizure, the use of second-line treatment: phenytoin, valproic acid or phenobarbital is required. SE that persists after the administration of benzodiazepines and phenytoin or another second-line AED at appropriate doses is defined as refractory and drug resistant and requires treatment in the intensive care unit (ICU). EEG monitoring is essential during therapy at this stage. Anesthesia is typically continued for an initial period of 24h followed by a slow reversal and is re-established if seizures recur. Anesthesia is usually administered either to the level of the “burst suppression pattern” or to obtain the “EEG suppression” pattern.
Conclusions
Experts agree that close and early cooperation with a neurologist and anesthetist aiming to reduce the risk of pharmacoresistant cases is an extremely important factor in the treatment of patients with SE. This report has educational, practical and organizational aspects, outlining a standard plan for SE management in Poland that will improve therapeutic efficacy
Mathematical Properties of a New Levin-Type Sequence Transformation Introduced by \v{C}\'{\i}\v{z}ek, Zamastil, and Sk\'{a}la. I. Algebraic Theory
\v{C}\'{\i}\v{z}ek, Zamastil, and Sk\'{a}la [J. Math. Phys. \textbf{44}, 962
- 968 (2003)] introduced in connection with the summation of the divergent
perturbation expansion of the hydrogen atom in an external magnetic field a new
sequence transformation which uses as input data not only the elements of a
sequence of partial sums, but also explicit estimates
for the truncation errors. The explicit
incorporation of the information contained in the truncation error estimates
makes this and related transformations potentially much more powerful than for
instance Pad\'{e} approximants. Special cases of the new transformation are
sequence transformations introduced by Levin [Int. J. Comput. Math. B
\textbf{3}, 371 - 388 (1973)] and Weniger [Comput. Phys. Rep. \textbf{10}, 189
- 371 (1989), Sections 7 -9; Numer. Algor. \textbf{3}, 477 - 486 (1992)] and
also a variant of Richardson extrapolation [Phil. Trans. Roy. Soc. London A
\textbf{226}, 299 - 349 (1927)]. The algebraic theory of these transformations
- explicit expressions, recurrence formulas, explicit expressions in the case
of special remainder estimates, and asymptotic order estimates satisfied by
rational approximants to power series - is formulated in terms of hitherto
unknown mathematical properties of the new transformation introduced by
\v{C}\'{\i}\v{z}ek, Zamastil, and Sk\'{a}la. This leads to a considerable
formal simplification and unification.Comment: 41 + ii pages, LaTeX2e, 0 figures. Submitted to Journal of
Mathematical Physic
Fibroblast activation protein-α expression in fibroblasts is common in the tumor microenvironment of colorectal cancer and may serve as a therapeutic target
Background: Colorectal cancer (CRC) is still one of the leading causes of cancer death worldwide, emphasizing the need for further diagnostic and therapeutic approaches. Cancer invasion and metastasis are affected by the tumor microenvironment (TME), with cancer-associated fibroblasts (CAF) being the predominant cellular component. An important marker for CAF is fibroblast activation protein-α (FAP) which has been evaluated as therapeutic target for, e.g., radioligand therapy. The aim of this study was to examine CRC regarding the FAP expression as a candidate for targeted therapy.Methods: 67 CRC, 24 adenomas, 18 tissue samples of inflammation sites and 28 non-neoplastic, non-inflammatory tissue samples of colonic mucosa were evaluated for immunohistochemical FAP expression of CAF in tissue microarrays. The results were correlated with clinicopathological data, tumor biology and concurrent expression of additional immunohistochemical parameters.Results: 53/67 (79%) CRC and 6/18 (33%) inflammatory tissue specimens showed expression of FAP. However, FAP was only present in 1/24 (4%) adenomas and absent in normal mucosa (0/28). Thus, FAP expression in CRC was significantly higher than in the other investigated groups. Within the CRC cohort, expression of FAP did not correlate with tumor stage, grading or the MSI status. However, it was observed that tumors exhibiting high immunohistochemical expression of Ki-67, CD3, p53, and β-Catenin showed a significantly higher incidence of FAP expression.Conclusion: In the crosstalk between tumor cells and TME, CAF play a key role in carcinogenesis and metastatic spread. Expression of FAP was detectable in the majority of CRC but nearly absent in precursor lesions and non-neoplastic, non-inflammatory tissue. This finding indicates that FAP has the potential to emerge as a target for new diagnostic and therapeutic concepts in CRC. Additionally, the association between FAP expression and other immunohistochemical parameters displays the interaction between different components of the TME and demands further investigation
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