The project Lunar Volatiles Mobile Instrumentation-Extended (LUVMI-X) developed an initial system design as well as payload and mobility breadboards for a small, lightweight rover dedicated for in ...situ exploration of the lunar south pole. One of the proposed payloads is the Volatiles Identification by Laser Analysis instrument (VOILA), which uses laser-induced breakdown spectroscopy (LIBS) to analyze the elemental composition of the lunar surface with an emphasis on sampling regolith and the detection of hydrogen for the inference of the presence of water. It is designed to analyze targets in front of the rover at variable focus between 300 mm and 500 mm. The spectrometer covers the wavelength range from 350 nm to 790 nm, which includes the hydrogen line at 656.3 nm as well as spectral lines of most major rock-forming elements. We report here the scientific input that fed into the concept and design of the VOILA instrument configuration for the LUVMI-X rover. Moreover, we present the measurements performed with the breadboard laboratory setup for VOILA at DLR Berlin that focused on verifying the performance of the designed LIBS instrument in particular for the detection and quantification of hydrogen and other major rock forming elements in the context of in situ lunar surface analysis.
Gain dynamics and refractive index changes in fiber amplifiers are important in many areas. For example, the knowledge of the frequency responses for seed and pump power modulation are required to ...actively stabilize low noise fiber amplifiers. Slow and fast light via coherent population oscillations rely on the change of group index to delay or advance pulses, and refractive index changes in fiber amplifiers are a possible explanation for mode fluctuations in high power fiber amplifiers. Here, we analyze the frequency dependent influence of seed and pump power modulation on the fiber amplifier output power and the refractive index. We explain the observed power and refractive index modulation with an analytic model originally developed for telecom amplifiers and discuss a further simplification of the model.
Acquired mutations or altered gene expression patterns in brain metastases (BM) and/or leptomeningeal metastases (LM) of breast cancer may play a role in therapy-resistance and offer new molecular ...targets and treatment options. Despite expanding knowledge of genetic alterations in breast cancer and their metastases, clinical applications for patients with central nervous system (CNS) metastases are currently limited. An emerging tool are DNA-techniques that may detect genetic alterations of the CNS metastases in the cerebrospinal fluid (CSF). In this review we discuss genetic studies in breast cancer and CNS metastases and the role of liquid biopsies in CSF.
We report on theoretical and experimental investigations on spontaneous and stimulated Brillouin scattering during operation of a high-power single-frequency polarization-maintaining ytterbium doped ...fiber amplifier. For different amplifier configurations with co- and counter-propagating seed and pump radiation the evolution of Brillouin scattering spectra was investigated with a heterodyne detection scheme. Spontaneous Brillouin gain spectra at low powers were additionally investigated using a pump-probe technique. The data obtained from these experiments have been compared with a theoretical model based on coupled intensity equations. A Brillouin scattering suppression has been investigated theoretically and experimentally with externally applied temperature gradients along the fiber resulting in up to 3.5 dB suppression and 115 W of amplifier output power.
In view of the rapid extension of offshore wind farms, there is an urgent need to improve our knowledge on possible adverse effects of underwater sound generated by pile-driving. Mortality and ...injuries have been observed in fish exposed to loud impulse sounds, but knowledge on the sound levels at which (sub-)lethal effects occur is limited for juvenile and adult fish, and virtually non-existent for fish eggs and larvae. A device was developed in which fish larvae can be exposed to underwater sound. It consists of a rigid-walled cylindrical chamber driven by an electro-dynamical sound projector. Samples of up to 100 larvae can be exposed simultaneously to a homogeneously distributed sound pressure and particle velocity field. Recorded pile-driving sounds could be reproduced accurately in the frequency range between 50 and 1000 Hz, at zero to peak pressure levels up to 210 dB re 1µPa(2) (zero to peak pressures up to 32 kPa) and single pulse sound exposure levels up to 186 dB re 1µPa(2)s. The device was used to examine lethal effects of sound exposure in common sole (Solea solea) larvae. Different developmental stages were exposed to various levels and durations of pile-driving sound. The highest cumulative sound exposure level applied was 206 dB re 1µPa(2)s, which corresponds to 100 strikes at a distance of 100 m from a typical North Sea pile-driving site. The results showed no statistically significant differences in mortality between exposure and control groups at sound exposure levels which were well above the US interim criteria for non-auditory tissue damage in fish. Although our findings cannot be extrapolated to fish larvae in general, as interspecific differences in vulnerability to sound exposure may occur, they do indicate that previous assumptions and criteria may need to be revised.
To the best of our knowledge we report for the first time on an Yb-sensitized Er-doped cladding pumped fiber amplifier which is simultaneously seeded by two single-frequency lasers operating at 1556 ...nm and 1064 nm, respectively. This mode of operation ensures stable amplifier operation by reducing the gain around 1 microm wavelength to the large signal gain value, while having no significant effect on the slope efficiency of the amplification process at 1556 nm when pumping at 976 nm. We were able to demonstrate stable output power of 8.7 W at 1556 nm with an amplifier gain of > 22 dB, a co-propagating pumping scheme and the power limitation only being set by the available amount of pump power.
An increase in public awareness of noise pollution and the impact of noise on human health has led to the need for enhanced insight in complex noise situations. This insight is commonly obtained ...either by brief measurements or by evaluation of a simplified acoustic model. Both of these approaches however have limitations in complex noise situations. Noise monitoring can be an appropriate and cost efficient measure to obtain more insight, for it allows to measure at many locations for long periods of time. Monitoring can for example be used to improve the accuracy of models or to assess and respond to changes in the acoustic situation. Several monitoring approaches, for various applications, have been developed or are under development. In the first part of this paper an overview is given of current developments in acoustic monitoring networks and their key aspects. Sensor networks for environmental noise monitoring are here divided into four different categories, distinguished by five aspects: hardware costs, scalability, flexibility, reliability and accuracy. These five aspects determine the range of applications for which a network is suited. In the second part of this paper a monitoring network developed in-house is used to further illustrate the relevance of these aspects. This network was designed to facilitate research into the field of acoustic monitoring networks and is used to experiment with and learn from a broad field of applications.
Since the network is not designed for just one application, it has a special focus on flexibility and scalability. This allows the network to cope with the requirement of various applications with different scales. In the third section of this paper three applications of the network are shown to illustrate the five aspects.
Collinear coherent combination of multiple single frequency fiber amplifiers is a promising approach to realize the high power laser sources required for 3rd generation gravitational wave detectors ...(GWD), as long as the stringent requirements on the beam quality and noise properties can be met. Here, we report the beam quality and noise properties of two coherently combined 10 W single frequency amplifiers with respect to the requirements of GWD. The combining efficiency was larger than 95% with 97% of the combined beam in the fundamental spatial mode. There was no significant noise increase compared to the fluctuations of the single amplifier.
Background: Primary vitreoretinal lymphoma (PVRL) is either unilateral or bilateral at initial presentation. Progression to a central nervous system (CNS) lymphoma is regularly observed and these ...patients seem to have an inferior survival. Knowledge of the predictive value of laterality for CNS progression may facilitate risk stratification and the development of more effective treatment strategies, and eventually, improve outcomes. The objective of this analysis is to estimate the risk of CNS progression for patients with bilateral versus unilateral involvement of PVRL. Methods: Systematic literature search for studies on CNS progression in PVRL with bilateral and unilateral involvement according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. We assessed the risk of bias and the methodological quality of studies using the Quality in Prognosis Studies (QUIPS) tool. Risk ratios of CNS progression in PVRL with bilateral and unilateral involvement were calculated and combined via a meta-analysis. Results: Twenty-five small-sized (total n = 371 cases) studies were included. The majority of the studies were at medium to high risk of bias. Results suggest no significant difference in CNS progression between bilateral and unilateral PVRL, with a pooled relative risk ratio of 1.12 (95% confidence interval 0.89–1.41). Conclusions: CNS progression is common in PVRL. From the limited available evidence, there is no significant difference in CNS progression between bilateral and unilateral PVRL.
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