@article{XueLiuWangetal.2019, author = {Xue, Rui and Liu, Ruo-Yu and Wang, Xiang-Yu and Yan, Huirong and B{\"o}ttcher, Markus}, title = {On the minimum jet power of TeV BL Lac objects in the p-gamma model}, series = {The astrophysical journal : an international review of spectroscopy and astronomical physics}, volume = {871}, journal = {The astrophysical journal : an international review of spectroscopy and astronomical physics}, number = {1}, publisher = {IOP Publ. Ltd.}, address = {Bristol}, issn = {0004-637X}, doi = {10.3847/1538-4357/aaf720}, pages = {10}, year = {2019}, abstract = {We study the requirement of the jet power in the conventional p-gamma models (photopion production and Bethe-Heitler pair production) for TeV BL Lac objects. We select a sample of TeV BL Lac objects whose spectral energy distributions are difficult to explain by the one-zone leptonic model. Based on the relation between the p-gamma interaction efficiency and the opacity of gamma gamma absorption, we find that the detection of TeV emission poses upper limits on the p-gamma interaction efficiencies in these sources and hence minimum jet powers can be derived accordingly. We find that the obtained minimum jet powers exceed the Eddington luminosity of the supermassive black holes (SMBHs). Implications for the accretion mode of the SMBHs in these BL Lac objects and the origin of their TeV emissions are discussed.}, language = {en} } @article{LiuYanWangetal.2019, author = {Liu, Ruo-Yu and Yan, Huirong and Wang, Xiang-Yu and Shao, Shi and Li, Hui}, title = {Gamma-Ray production in the extended halo of the galaxy and possible implications for the origin of galactic cosmic rays}, series = {The astrophysical journal : an international review of spectroscopy and astronomical physics}, volume = {871}, journal = {The astrophysical journal : an international review of spectroscopy and astronomical physics}, number = {1}, publisher = {IOP Publ. Ltd.}, address = {Bristol}, issn = {0004-637X}, doi = {10.3847/1538-4357/aaf567}, pages = {11}, year = {2019}, abstract = {Various studies have implied the existence of a gaseous halo around the Galaxy extending out to similar to 100 kpc. Galactic cosmic rays (CRs) that propagate to the halo, either by diffusion or by convection with the possibly existing large-scale Galactic wind, can interact with the gas therein and produce gamma-rays via proton-proton collision. We calculate the CR distribution in the halo and the gamma-ray flux, and explore the dependence of the result on model parameters such as diffusion coefficient, CR luminosity, and CR spectral index. We find that the current measurement of isotropic gamma-ray background (IGRB) at less than or similar to TeV with the Fermi Large Area Telescope already approaches a level that can provide interesting constraints on the properties of Galactic CR (e.g., with CR luminosity L-CR <= 1041 erg s(-1)). We also discuss the possibilities of the Fermi bubble and IceCube neutrinos originating from the proton-proton collision between CRs and gas in the halo, as well as the implication of our results for the baryon budget of the hot circumgalactic medium of our Galaxy. Given that the isotropic gamma-ray background is likely to be dominated by unresolved extragalactic sources, future telescopes may extract more individual sources from the IGRB, and hence put even more stringent restrictions on the relevant quantities (such as Galactic CR luminosity and baryon budget in the halo) in the presence of a turbulent halo that we consider.}, language = {en} } @misc{LewandowskyCowtanRisbeyetal.2018, author = {Lewandowsky, Stephan and Cowtan, Kevin and Risbey, James S. and Mann, Michael E. and Steinman, Byron A. and Oreskes, Naomi and Rahmstorf, Stefan}, title = {The 'pause' in global warming in historical context}, series = {Environmental research letters}, volume = {13}, journal = {Environmental research letters}, number = {12}, publisher = {IOP Publ. Ltd.}, address = {Bristol}, issn = {1748-9326}, doi = {10.1088/1748-9326/aaf372}, pages = {25}, year = {2018}, abstract = {We review the evidence for a putative early 21st-century divergence between global mean surface temperature (GMST) and Coupled Model Intercomparison Project Phase 5 (CMIP5) projections. We provide a systematic comparison between temperatures and projections using historical versions of GMST products and historical versions of model projections that existed at the times when claims about a divergence were made. The comparisons are conducted with a variety of statistical techniques that correct for problems in previous work, including using continuous trends and a Monte Carlo approach to simulate internal variability. The results show that there is no robust statistical evidence for a divergence between models and observations. The impression of a divergence early in the 21st century was caused by various biases in model interpretation and in the observations, and was unsupported by robust statistics.}, language = {en} } @article{BaranOstensenTeltingetal.2018, author = {Baran, Andrzej S. and Ostensen, R. H. and Telting, J. H. and Vos, Joris and Kilkenny, D. and Vuckovic, Maja and Reed, M. D. and Silvotti, R. and Jeffery, C. Simon and Parsons, Steven G. and Dhillon, V. S. and Marsh, T. R.}, title = {Pulsations and eclipse-time analysis of HW Vir}, series = {Monthly notices of the Royal Astronomical Society}, volume = {481}, journal = {Monthly notices of the Royal Astronomical Society}, number = {2}, publisher = {Oxford Univ. Press}, address = {Oxford}, issn = {0035-8711}, doi = {10.1093/mnras/sty2473}, pages = {2721 -- 2735}, year = {2018}, abstract = {We analysed recent K2 data of the short-period eclipsing binary system HW Vir, which consists of a hot subdwarf-B type primary with an M-dwarf companion. We determined the mid-times of eclipses, calculated O-C diagrams, and an average shift of the secondary minimum. Our results show that the orbital period is stable within the errors over the course of the 70 days of observations. Interestingly, the offset from mid-orbital phase between the primary and the secondary eclipses is found to be 1.62 s. If the shift is explained solely by light-travel time, the mass of the sdB primary must be 0.26 M-circle dot, which is too low for the star to be core-helium burning. However, we argue that this result is unlikely to be correct and that a number of effects caused by the relative sizes of the stars conspire to reduce the effective light-travel time measurement. After removing the flux variation caused by the orbit, we calculated the amplitude spectrum to search for pulsations. The spectrum clearly shows periodic signal from close to the orbital frequency up to 4600 mu Hz, with the majority of peaks found below 2600 mu Hz. The amplitudes are below 0.1 part-per-thousand, too low to be detected with ground-based photometry. Thus, the high-precision data from the Kepler spacecraft has revealed that the primary of the HW Vir system is a pulsating sdBV star. We argue that the pulsation spectrum of the primary in HW Vir differs from that in other sdB stars due to its relatively fast rotation that is (nearly) phase-locked with the orbit.}, language = {en} } @misc{DolezalovaKubatovaKubatetal.2019, author = {Dolezalova, Barbora and Kubatova, Brankica and Kubat, Jiri and Hamann, Wolf-Rainer}, title = {The Quasi-WR Star HD 45166 Revisited}, series = {Radiative signatures from the cosmos}, volume = {519}, journal = {Radiative signatures from the cosmos}, publisher = {Astronomical soc pacific}, address = {San Fransisco}, isbn = {978-1-58381-925-8}, issn = {1050-3390}, pages = {197 -- 200}, year = {2019}, abstract = {We studied the wind of the quasi Wolf-Rayet (qWR) star HD 45166. As a first step we modeled the observed UV spectra of this star by means of the state-of-the-art Potsdam Wolf-Rayet (PoWR) atmosphere code. We inferred the wind parameters and compared them with previous findings.}, language = {en} } @article{GajdaWylomanskaKantzetal.2018, author = {Gajda, J. and Wylomanska, Agnieszka and Kantz, Holger and Chechkin, Aleksei V. and Sikora, Grzegorz}, title = {Large deviations of time-averaged statistics for Gaussian processes}, series = {Statistics \& Probability Letters}, volume = {143}, journal = {Statistics \& Probability Letters}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0167-7152}, doi = {10.1016/j.spl.2018.07.013}, pages = {47 -- 55}, year = {2018}, abstract = {In this paper we study the large deviations of time averaged mean square displacement (TAMSD) for Gaussian processes. The theory of large deviations is related to the exponential decay of probabilities of large fluctuations in random systems. From the mathematical point of view a given statistics satisfies the large deviation principle, if the probability that it belongs to a certain range decreases exponentially. The TAMSD is one of the main statistics used in the problem of anomalous diffusion detection. Applying the theory of generalized chi-squared distribution and sub-gamma random variables we prove the upper bound for large deviations of TAMSD for Gaussian processes. As a special case we consider fractional Brownian motion, one of the most popular models of anomalous diffusion. Moreover, we derive the upper bound for large deviations of the estimator for the anomalous diffusion exponent. (C) 2018 Elsevier B.V. All rights reserved.}, language = {en} } @article{MardoukhiChechkinMetzler2020, author = {Mardoukhi, Yousof and Chechkin, Aleksei V. and Metzler, Ralf}, title = {Spurious ergodicity breaking in normal and fractional Ornstein-Uhlenbeck process}, series = {New Journal of Physics}, volume = {22}, journal = {New Journal of Physics}, publisher = {IOP}, address = {London}, issn = {1367-2630}, doi = {10.1088/1367-2630/ab950b}, pages = {18}, year = {2020}, abstract = {The Ornstein-Uhlenbeck process is a stationary and ergodic Gaussian process, that is fully determined by its covariance function and mean. We show here that the generic definitions of the ensemble- and time-averaged mean squared displacements fail to capture these properties consistently, leading to a spurious ergodicity breaking. We propose to remedy this failure by redefining the mean squared displacements such that they reflect unambiguously the statistical properties of any stochastic process. In particular we study the effect of the initial condition in the Ornstein-Uhlenbeck process and its fractional extension. For the fractional Ornstein-Uhlenbeck process representing typical experimental situations in crowded environments such as living biological cells, we show that the stationarity of the process delicately depends on the initial condition.}, language = {en} } @book{Feldmeier2019, author = {Feldmeier, Achim}, title = {Theoretical Fluid Dynamics}, series = {Theoretical and Mathematical Physics}, journal = {Theoretical and Mathematical Physics}, publisher = {Springer}, address = {Cham}, isbn = {978-3-030-31021-9 (online)}, doi = {10.1007/978-3-030-31022-6}, pages = {XVI, 569}, year = {2019}, language = {en} } @misc{GruendePaterShowalteretal.2006, author = {Gr{\"u}n, Eberhard and de Pater, Imke and Showalter, Mark and Spahn, Frank and Srama, Ralf}, title = {Physics of dusty rings: History and perspective}, series = {Planetary and space science}, volume = {54}, journal = {Planetary and space science}, number = {9-10}, publisher = {Elsevier}, address = {Oxford}, issn = {0032-0633}, doi = {10.1016/j.pss.2006.05.005}, pages = {837 -- 843}, year = {2006}, language = {en} } @article{MakuchBrilliantovSremcevicetal.2006, author = {Makuch, Martin and Brilliantov, Nikolai V. and Sremcevic, Miodrag and Spahn, Frank and Krivov, Alexander V.}, title = {Stochastic circumplanetary dynamics of rotating non-spherical dust particles}, series = {Planetary and space science}, volume = {54}, journal = {Planetary and space science}, number = {9-10}, publisher = {Elsevier}, address = {Oxford}, issn = {0032-0633}, doi = {10.1016/j.pss.2006.05.006}, pages = {855 -- 870}, year = {2006}, abstract = {We develop a model of stochastic radiation pressure for rotating non-spherical particles and apply the model to circumplanetary dynamics of dust grains. The stochastic properties of the radiation pressure are related to the ensemble-averaged characteristics of the rotating particles, which are given in terms of the rotational time-correlation function of a grain. We investigate the model analytically and show that an ensemble of particle trajectories demonstrates a diffusion-like behaviour. The analytical results are compared with numerical simulations, performed for the motion of the dusty ejecta from Deimos in orbit around Mars. We find that the theoretical predictions are in a good agreement with the simulation results. The agreement however deteriorates at later time, when the impact of non-linear terms, neglected in the analytic approach, becomes significant. Our results indicate that the stochastic modulation of the radiation pressure can play an important role in the circumplanetary dynamics of dust and may in case of some dusty systems noticeably alter an optical depth. (c) 2006 Elsevier Ltd. All rights reserved.}, language = {en} } @article{BeckerPettiniRafelskietal.2019, author = {Becker, George D. and Pettini, Max and Rafelski, Marc and Boera, Elisa and Christensen, Lise and Cupani, Guido and Ellison, Sara L. and Farina, Emanuele Paolo and Fumagalli, Michele and Lopez, Sebastian and Neeleman, Marcel and Ryan-Weber, Emma and Worseck, Gabor}, title = {The Evolution of OI over 3.2 < z < 6.5: Reionization of the Circumgalactic Medium}, series = {The astrophysical journal : an international review of spectroscopy and astronomical physics}, volume = {883}, journal = {The astrophysical journal : an international review of spectroscopy and astronomical physics}, number = {2}, publisher = {IOP Publ. Ltd.}, address = {Bristol}, issn = {0004-637X}, doi = {10.3847/1538-4357/ab3eb5}, pages = {37}, year = {2019}, abstract = {We present a survey for metal absorption systems traced by neutral oxygen over 3.2 < z < 6.5. Our survey uses Keck/ESI and VLT/X-Shooter spectra of 199 QSOs with redshifts up to 6.6. In total, we detect 74 OI absorbers, of which 57 are separated from the background QSO by more than 5000 km s(-1). We use a maximum likelihood approach to fit the distribution of OI lambda 1302 equivalent widths in bins of redshift and from this determine the evolution in number density of absorbers with W-1302 > 0.05 angstrom, of which there are 49 nonproximate systems in our sample. We find that the number density does not monotonically increase with decreasing redshift, as would naively be expected from the buildup of metal-enriched circumgalactic gas with time. The number density over 4.9 < z < 5.7 is a factor of 1.7-4.1 lower (68\% confidence) than that over 5.7 < z < 6.5, with a lower value at z < 5.7 favored with 99\% confidence. This decrease suggests that the fraction of metals in a low-ionization phase is larger at z similar to 6 than at lower redshifts. Absorption from highly ionized metals traced by CIV is also weaker in higher-redshift OI systems, supporting this picture. The evolution of OI absorbers implies that metal-enriched circumgalactic gas at z similar to 6 is undergoing an ionization transition driven by a strengthening ultraviolet background. This in turn suggests that the reionization of the diffuse intergalactic medium may still be ongoing at or only recently ended by this epoch.}, language = {en} } @article{WilkinParrishYangetal.2019, author = {Wilkin, Kyle J. and Parrish, Robert M. and Yang, Jie and Wolf, Thomas J. A. and Nunes, J. Pedro F. and G{\"u}hr, Markus and Li, Renkai and Shen, Xiaozhe and Zheng, Qiang and Wang, Xijie and Martinez, Todd J. and Centurion, Martin}, title = {Diffractive imaging of dissociation and ground-state dynamics in a complex molecule}, series = {Physical review : A, Atomic, molecular, and optical physics}, volume = {100}, journal = {Physical review : A, Atomic, molecular, and optical physics}, number = {2}, publisher = {American Physical Society}, address = {College Park}, issn = {2469-9926}, doi = {10.1103/PhysRevA.100.023402}, pages = {10}, year = {2019}, abstract = {We have investigated the structural dynamics in photoexcited 1,2-diiodotetrafluoroethane molecules (C2F4I2) in the gas phase experimentally using ultrafast electron diffraction and theoretically using FOMO-CASCI excited-state dynamics simulations. The molecules are excited by an ultraviolet femtosecond laser pulse to a state characterized by a transition from the iodine 5p perpendicular to orbital to a mixed 5p parallel to sigma hole and CF2 center dot antibonding orbital, which results in the cleavage of one of the carbon-iodine bonds. We have observed, with sub-Angstrom resolution, the motion of the nuclear wave packet of the dissociating iodine atom followed by coherent vibrations in the electronic ground state of the C2F4I radical. The radical reaches a stable classical (nonbridged) structure in less than 200 fs.}, language = {en} } @article{WolfParrishMyhreetal.2019, author = {Wolf, Thomas J. A. and Parrish, Robert M. and Myhre, Rolf H. and Martinez, Todd J. and Koch, Henrik and G{\"u}hr, Markus}, title = {Observation of Ultrafast Intersystem Crossing in Thymine by Extreme Ultraviolet Time-Resolved Photoelectron Spectroscopy}, series = {The journal of physical chemistry : A, Molecules, spectroscopy, kinetics, environment \& general theory}, volume = {123}, journal = {The journal of physical chemistry : A, Molecules, spectroscopy, kinetics, environment \& general theory}, number = {32}, publisher = {American Chemical Society}, address = {Washington}, issn = {1089-5639}, doi = {10.1021/acs.jpca.9b05573}, pages = {6897 -- 6903}, year = {2019}, abstract = {We studied the photoinduced ultrafast relaxation dynamics of the nucleobase thymine using gas-phase time-resolved photoelectron spectroscopy. By employing extreme ultraviolet pulses from high harmonic generation for photoionization, we substantially extend our spectral observation window with respect to previous studies. This enables us to follow relaxation of the excited state population all the way to low-lying electronic states including the ground state. In thymine, we observe relaxation from the optically bright (1)pi pi* state of thymine to a dark (1)n pi* state within 80 +/- 30 fs. The (1)n pi* state relaxes further within 3.5 +/- 0.3 ps to a low-lying electronic state. By comparison with quantum chemical simulations, we can unambiguously assign its spectroscopic signature to the (3)pi pi* state. Hence, our study draws a comprehensive picture of the relaxation mechanism of thymine including ultrafast intersystem crossing to the triplet manifold.}, language = {en} } @article{RinaldiFormisanoKappeletal.2019, author = {Rinaldi, G. and Formisano, M. and Kappel, David and Capaccioni, F. and Bockelee-Morvan, D. and Cheng, Y-C and Vincent, J-B and Deshapriya, P. and Arnold, G. and Capria, M. T. and Ciarniello, M. and De Sanctis, M. C. and Doose, L. and Erard, S. and Federico, C. and Filacchione, G. and Fink, U. and Leyrat, C. and Longobardo, A. and Magni, G. and Mighorini, A. and Mottola, S. and Naletto, G. and Raponi, A. and Taylor, F. and Tosi, F. and Tozzi, G. P. and Salatti, M.}, title = {Analysis of night-side dust activity on comet 67P observed by VIRTIS-M}, series = {Astronomy and astrophysics : an international weekly journal}, volume = {630}, journal = {Astronomy and astrophysics : an international weekly journal}, publisher = {EDP Sciences}, address = {Les Ulis}, issn = {1432-0746}, doi = {10.1051/0004-6361/201834907}, pages = {16}, year = {2019}, abstract = {On 2015 July 18, near perihelion at a heliocentric distance of 1.28 au, the Visible InfraRed Thermal Imaging Spectrometer (VIRTIS-M) on board the Rosetta spacecraft had the opportunity of observing dust activity in the inner coma with a view of the night side (shadowed side) of comet 67P/Churyumov-Gerasimenko. At the time of the measurements we present here, we observe a dust plume that originates on the far side of the nucleus. We are able to identify the approximate location of its source at the boundary between the Hapi and Anuket regions, and we find that it has been in darkness for some hours before the observation. Assuming that this time span is equal to the conductive time scale, we obtain a thermal inertia in the range 25-36 W K-1 m(-2) s(-1/2). These thermal inertia values can be used to verify with a 3D finite-element method (REM) numerical code whether the surface and subsurface temperatures agree with the values found in the literature. We explored three different configurations: (1) a layer of water ice mixed with dust beneath a dust mantle of 5 mm with thermal inertia of 36 J m(-2) K-1 S-0.5 ; (2) the same structure, but with thermal inertia of 100 J m(-2) K-1 S-0.5; (3) an ice-dust mixture that is directly exposed. Of these three configurations, the first seems to be the most reasonable, both for the low thermal inertia and for the agreement with the surface and subsurface temperatures that have been found for the comet 67P/Churyumov-Gerasimenko. The spectral properties of the plume show that the visible dust color ranged from 16 +/- 4.8\%/100 nm to 13 +/- 2.6\%/100 nm, indicating that this plume has no detectable color gradient. The morphology of the plume can be classified as a narrow jet that has an estimated total ejected mass of between 6 and 19 tons when we assume size distribution indices between -2.5 and -3.}, language = {en} } @article{TubianaRinaldiGuettleretal.2019, author = {Tubiana, C. and Rinaldi, G. and Guettler, C. and Snodgrass, C. and Shi, X. and Hu, X. and Marschall, R. and Fulle, M. and Bockeele-Morvan, D. and Naletto, G. and Capaccioni, F. and Sierks, H. and Arnold, G. and Barucci, M. A. and Bertaux, J-L and Bertini, I and Bodewits, D. and Capria, M. T. and Ciarniello, M. and Cremonese, G. and Crovisier, J. and Da Deppo, V and Debei, S. and De Cecco, M. and Deller, J. and De Sanctis, M. C. and Davidsson, B. and Doose, L. and Erard, S. and Filacchione, G. and Fink, U. and Formisano, M. and Fornasier, S. and Gutierrez, P. J. and Ip, W-H and Ivanovski, S. and Kappel, David and Keller, H. U. and Kolokolova, L. and Koschny, D. and Krueger, H. and La Forgia, F. and Lamy, P. L. and Lara, L. M. and Lazzarin, M. and Levasseur-Regourd, A. C. and Lin, Z-Y and Longobardo, A. and Lopez-Moreno, J. J. and Marzari, F. and Migliorini, A. and Mottola, S. and Rodrigo, R. and Taylor, F. and Toth, I and Zakharov, V}, title = {Diurnal variation of dust and gas production in comet 67P/Churyumov-Gerasimenko at the inbound equinox as seen by OSIRIS and VIRTIS-M on board Rosetta}, series = {Astronomy and astrophysics : an international weekly journal}, volume = {630}, journal = {Astronomy and astrophysics : an international weekly journal}, publisher = {EDP Sciences}, address = {Les Ulis}, issn = {1432-0746}, doi = {10.1051/0004-6361/201834869}, pages = {14}, year = {2019}, abstract = {Context. On 27 April 2015, when comet 67P/Churyumov-Gerasimenko was at 1.76 au from the Sun and moving toward perihelion, the OSIRIS and VIRTIS-M instruments on board the Rosetta spacecraft simultaneously observed the evolving dust and gas coma during a complete rotation of the comet. Aims. We aim to characterize the spatial distribution of dust, H2O, and CO2 gas in the inner coma. To do this, we performed a quantitative analysis of the release of dust and gas and compared the observed H2O production rate with the rate we calculated using a thermophysical model. Methods. For this study we selected OSIRIS WAC images at 612 nm (dust) and VIRTIS-M image cubes at 612 nm, 2700 nm (H2O emission band), and 4200 nm (CO2 emission band). We measured the average signal in a circular annulus to study the spatial variation around the comet, and in a sector of the annulus to study temporal variation in the sunward direction with comet rotation, both at a fixed distance of 3.1 km from the comet center. Results. The spatial correlation between dust and water, both coming from the sunlit side of the comet, shows that water is the main driver of dust activity in this time period. The spatial distribution of CO2 is not correlated with water and dust. There is no strong temporal correlation between the dust brightness and water production rate as the comet rotates. The dust brightness shows a peak at 0 degrees subsolar longitude, which is not pronounced in the water production. At the same epoch, there is also a maximum in CO2 production. An excess of measured water production with respect to the value calculated using a simple thermophysical model is observed when the head lobe and regions of the southern hemisphere with strong seasonal variations are illuminated (subsolar longitude 270 degrees-50 degrees). A drastic decrease in dust production when the water production (both measured and from the model) displays a maximum occurs when typical northern consolidated regions are illuminated and the southern hemisphere regions with strong seasonal variations are instead in shadow (subsolar longitude 50 degrees-90 degrees). Possible explanations of these observations are presented and discussed.}, language = {en} } @article{BaranTeltingJefferyetal.2019, author = {Baran, Andrzej S. and Telting, J. H. and Jeffery, C. Simon and Ostensen, R. H. and Vos, Joris and Reed, M. D. and Vŭcković, Maja}, title = {K2 observations of the sdBV plus dM/bd binaries PHL457 and EQPsc}, series = {Monthly notices of the Royal Astronomical Society}, volume = {489}, journal = {Monthly notices of the Royal Astronomical Society}, number = {2}, publisher = {Oxford Univ. Press}, address = {Oxford}, issn = {0035-8711}, doi = {10.1093/mnras/stz2209}, pages = {1556 -- 1571}, year = {2019}, abstract = {We present an analysis of two pulsating subdwarf B stars PHL 457 and EQ Psc observed during the K2 mission. The K2 light curves of both stars show variation consistent with irradiation of a cooler companion by the hot subdwarf. They also show higher frequency oscillations consistent with pulsation. Using new spectroscopic data, we measured the radial velocity, effective temperature, surface gravity, and helium abundance of both hot subdwarfs as a function of orbital phase. We confirm the previously published spectroscopic orbit of PHL 457, and present the first spectroscopic orbit of EQ Psc. The orbital periods are 0.313 and 0.801 d, respectively. For EQPsc, we find a strong correlation between T-eff and orbital phase, due to contribution of light from the irradiated companion. We calculated amplitude spectra, identified significant pulsation frequencies, and searched for multiplets and asymptotic period spacings. By means of multiplets and period spacing, we identified the degrees of several pulsation modes in each star. The g-mode multiplets indicate subsynchronous core rotation with periods of 4.6 d (PHL 457) and 9.4 d (EQ Psc). We made spectral energy disctribution (SED) fits of PHL 457 and EQ Psc using available broad-band photometry and Gaia data. While the SED of PHL 457 shows no evidence of a cool companion, the SED for EQPsc clearly shows an infrared (IR) access consistent with a secondary with a temperature of about 6800K and a radius of 0.23 R-circle dot. This is the first detection of an IR access in any sdB + dM binary.}, language = {en} } @article{EliazarMetzlerReuveni2019, author = {Eliazar, Iddo and Metzler, Ralf and Reuveni, Shlomi}, title = {Poisson-process limit laws yield Gumbel max-min and min-max}, series = {Physical review : E, Statistical, nonlinear and soft matter physics}, volume = {100}, journal = {Physical review : E, Statistical, nonlinear and soft matter physics}, number = {2}, publisher = {American Physical Society}, address = {College Park}, issn = {2470-0045}, doi = {10.1103/PhysRevE.100.022129}, pages = {12}, year = {2019}, abstract = {"A chain is only as strong as its weakest link" says the proverb. But what about a collection of statistically identical chains: How long till all chains fail? The answer to this question is given by the max-min of a matrix whose (i,j)entry is the failure time of link j of chain i: take the minimum of each row, and then the maximum of the rows' minima. The corresponding min-max is obtained by taking the maximum of each column, and then the minimum of the columns' maxima. The min-max applies to the storage of critical data. Indeed, consider multiple backup copies of a set of critical data items, and consider the (i,j) matrix entry to be the time at which item j on copy i is lost; then, the min-max is the time at which the first critical data item is lost. In this paper we address random matrices whose entries are independent and identically distributed random variables. We establish Poisson-process limit laws for the row's minima and for the columns' maxima. Then, we further establish Gumbel limit laws for the max-min and for the min-max. The limit laws hold whenever the entries' distribution has a density, and yield highly applicable approximation tools and design tools for the max-min and min-max of large random matrices. A brief of the results presented herein is given in: Gumbel central limit theorem for max-min and min-max}, language = {en} } @article{EliazarMetzlerReuveni2019, author = {Eliazar, Iddo and Metzler, Ralf and Reuveni, Shlomi}, title = {Gumbel central limit theorem for max-min and min-max}, series = {Physical review : E, Statistical, nonlinear and soft matter physics}, volume = {100}, journal = {Physical review : E, Statistical, nonlinear and soft matter physics}, number = {2}, publisher = {American Physical Society}, address = {College Park}, issn = {2470-0045}, doi = {10.1103/PhysRevE.100.020104}, pages = {6}, year = {2019}, abstract = {The max-min and min-max of matrices arise prevalently in science and engineering. However, in many real-world situations the computation of the max-min and min-max is challenging as matrices are large and full information about their entries is lacking. Here we take a statistical-physics approach and establish limit laws—akin to the central limit theorem—for the max-min and min-max of large random matrices. The limit laws intertwine random-matrix theory and extreme-value theory, couple the matrix dimensions geometrically, and assert that Gumbel statistics emerge irrespective of the matrix entries' distribution. Due to their generality and universality, as well as their practicality, these results are expected to have a host of applications in the physical sciences and beyond.}, language = {en} } @article{PoeschelBrilliantovFormella2006, author = {Poeschel, Thorsten and Brilliantov, Nikolai V. and Formella, Arno}, title = {Impact of high-energy tails on granular gas properties}, series = {Physical review : E, Statistical, nonlinear and soft matter physics}, volume = {74}, journal = {Physical review : E, Statistical, nonlinear and soft matter physics}, number = {4}, publisher = {The American Physical Society}, address = {College Park}, issn = {1539-3755}, doi = {10.1103/PhysRevE.74.041302}, pages = {5}, year = {2006}, abstract = {The velocity distribution function of granular gases in the homogeneous cooling state as well as some heated granular gases decays for large velocities as f proportional to exp(-const x nu). That is, its high-energy tail is overpopulated as compared with the Maxwell distribution. At the present time, there is no theory to describe the influence of the tail on the kinetic characteristics of granular gases. We develop an approach to quantify the overpopulated tail and analyze its impact on granular gas properties, in particular on the cooling coefficient. We observe and explain anomalously slow relaxation of the velocity distribution function to its steady state.}, language = {en} } @article{BaptistaGrebogiKoberle2006, author = {Baptista, Murilo da Silva and Grebogi, Celso and Koberle, Roland}, title = {Dynamically multilayered visual system of the multifractal fly}, series = {Physical review letters}, volume = {97}, journal = {Physical review letters}, number = {17}, publisher = {American Physical Society}, address = {College Park}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.97.178102}, pages = {4}, year = {2006}, language = {en} } @article{HamannGraefenerLiermann2006, author = {Hamann, Wolf-Rainer and Graefener, G. and Liermann, A.}, title = {The galactic WN stars - Spectral analyses with line-blanketed model atmospheres versus stellar evolution models with and without rotation}, series = {Astronomy and astrophysics : an international weekly journal}, volume = {457}, journal = {Astronomy and astrophysics : an international weekly journal}, number = {3}, publisher = {EDP Sciences}, address = {Les Ulis}, issn = {0004-6361}, doi = {10.1051/0004-6361:20065052}, pages = {1015 -- 1031}, year = {2006}, abstract = {Context. Very massive stars pass through the Wolf-Rayet (WR) stage before they finally explode. Details of their evolution have not yet been safely established, and their physics are not well understood. Their spectral analysis requires adequate model atmospheres, which have been developed step by step during the past decades and account in their recent version for line blanketing by the millions of lines from iron and iron-group elements. However, only very few WN stars have been re-analyzed by means of line-blanketed models yet. Aims. The quantitative spectral analysis of a large sample of Galactic WN stars with the most advanced generation of model atmospheres should provide an empirical basis for various studies about the origin, evolution, and physics of the Wolf-Rayet stars and their powerful winds. Methods. We analyze a large sample of Galactic WN stars by means of the Potsdam Wolf-Rayet (PoWR) model atmospheres, which account for iron line blanketing and clumping. The results are compared with a synthetic population, generated from the Geneva tracks for massive star evolution. Results. We obtain a homogeneous set of stellar and atmospheric parameters for the GalacticWN stars, partly revising earlier results. Conclusions. Comparing the results of our spectral analyses of the Galactic WN stars with the predictions of the Geneva evolutionary calculations, we conclude that there is rough qualitative agreement. However, the quantitative discrepancies are still severe, and there is no preference for the tracks that account for the effects of rotation. It seems that the evolution of massive stars is still not satisfactorily understood.}, language = {en} } @article{ZaikinKurths2006, author = {Zaikin, Alexey and Kurths, J{\"u}rgen}, title = {Optimal length transportation hypothesis to model proteasome product size distribution}, series = {Journal of biological physics : emphasizing physical principles in biological research ; an international journal for the formulation and application of mathematical models in the biological sciences}, volume = {32}, journal = {Journal of biological physics : emphasizing physical principles in biological research ; an international journal for the formulation and application of mathematical models in the biological sciences}, number = {3-4}, publisher = {Springer}, address = {Dordrecht}, issn = {0092-0606}, doi = {10.1007/s10867-006-9014-z}, pages = {231 -- 243}, year = {2006}, abstract = {This paper discusses translocation features of the 20S proteasome in order to explain typical proteasome length distributions. We assume that the protein transport depends significantly on the fragment length with some optimal length which is transported most efficiently. By means of a simple one-channel model, we show that this hypothesis can explain both the one- and the three-peak length distributions found in experiments. A possible mechanism of such translocation is provided by so-called fluctuation-driven transport.}, language = {en} } @article{DierckeKuckeinDenker2019, author = {Diercke, Andrea and Kuckein, Christoph and Denker, Carsten}, title = {Dynamics and connectivity of an extended arch filament system}, series = {Astronomy and astrophysics : an international weekly journal}, volume = {629}, journal = {Astronomy and astrophysics : an international weekly journal}, publisher = {EDP Sciences}, address = {Les Ulis}, issn = {1432-0746}, doi = {10.1051/0004-6361/201935583}, pages = {14}, year = {2019}, abstract = {Aims. In this study, we analyzed a filament system, which expanded between moving magnetic features (MMFs) of a decaying sunspot and opposite flux outside of the active region from the nearby quiet-Sun network. This configuration deviated from a classical arch filament system (AFS), which typically connects two pores in an emerging flux region. Thus, we called this system an extended AFS. We contrasted classical and extended AFSs with an emphasis on the complex magnetic structure of the latter. Furthermore, we examined the physical properties of the extended AFS and described its dynamics and connectivity. Methods. The extended AFS was observed with two instruments at the Dunn Solar Telescope (DST). The Rapid Oscillations in the Solar Atmosphere (ROSA) imager provided images in three different wavelength regions, which covered the dynamics of the extended AFS at different atmospheric heights. The Interferometric Bidimensional Spectropolarimeter (IBIS) provided spectroscopic Ha data and spectropolarimetric data that was obtained in the near-infrared (NIR) Call lambda 8542 angstrom line. We derived the corresponding line-of-sight (LOS) velocities and used He II lambda 304 angstrom extreme ultraviolet (EUV) images of the Atmospheric Imaging Assembly (AIA) and LOS magnetograms of the Helioseismic and Magnetic Imager (HMI) on board the Solar Dynamics Observatory (SDO) as context data. Results. The NIR Call Stokes-V maps are not suitable to definitively define a clear polarity inversion line and to classify this chromospheric structure. Nevertheless, this unusual AFS connects the MMFs of a decaying sunspot with the network field. At the southern footpoint, we measured that the flux decreases over time. We find strong downflow velocities at the footpoints of the extended AFS, which increase in a time period of 30 min. The velocities are asymmetric at both footpoints with higher velocities at the southern footpoint. An EUV brigthening appears in one of the arch filaments, which migrates from the northern footpoint toward the southern one. This activation likely influences the increasing redshift at the southern footpoint. Conclusions. The extended AFS exhibits a similar morphology as classical AFSs, for example, threaded filaments of comparable length and width. Major differences concern the connection from MMFs around the sunspot with the flux of the neighboring quietSun network, converging footpoint motions, and longer lifetimes of individual arch filaments of about one hour, while the extended AFS is still very dynamic.}, language = {en} } @article{SahaOwenOrretal.2019, author = {Saha, Sourav and Owen, Lewis A. and Orr, Elizabeth N. and Caffee, Marc W.}, title = {High-frequency Holocene glacier fluctuations in the Himalayan-Tibetan orogen}, series = {Quaternary science reviews : the international multidisciplinary research and review journal}, volume = {220}, journal = {Quaternary science reviews : the international multidisciplinary research and review journal}, publisher = {Elsevier}, address = {Oxford}, issn = {0277-3791}, doi = {10.1016/j.quascirev.2019.07.021}, pages = {372 -- 400}, year = {2019}, abstract = {Holocene glacial chronostratigraphies in glaciated valleys spread throughout the Himalayan-Tibetan orogen, including the Himalaya, Tibet, Pamir, and Tian Shan, are developed using a landsystems approach, detailed geomorphic mapping, and new and published Be-10 surface exposure dating. New studies in the Kulti valley of Lahul and the Parkachik valley of the Nun Kun massif of the Himalaya of northern India define three glacier advances at similar to 14.7, 12.2, 0.5 ka, in addition to one historically dated late 19th Century advance in the Kulti valley, and one Late Holocene advance at similar to 0.2 ka in the Parkachik valley. Three major climatic groups (subdivided into five climatic zones) are defined across the orogen using Cluster Analysis (CA) and Principal Component Analysis (PCA) to identify glaciated regions with comparable climatic characteristics to evaluate the timing, and extent of Holocene glacier advances across these regions. Our regional analyses across the Himalayan-Tibetan orogen suggest at least one Lateglacial (similar to 15.3-11.8 ka) and five Himalayan-Tibetan Holocene glacial stages (HTHS) at similar to 11.5-9.5, similar to 8.8-7.7, similar to 7.0-3.2, similar to 2.3-1.0, and <1 ka. The extent (amplitude) of glacier advances in 77 glaciated valleys is reconstructed and defined using equilibrium-line altitudes (ELAs). Modern glacier hypsometries are also assessed to help explain the intra-regional variations in glacier amplitudes during each regional glacier advance. A linear inverse glacier flow model is used to decipher the net changes in temperature (Delta T) between periods of reconstructed regional glacier advances in 66 glaciated valleys across different climatic regions throughout the orogen. The Be-10, ELAs, and Delta T data suggest enhanced monsoonal and increased precipitation during the Early Holocene, followed by relative cooling and increased aridity during the Mid- and Late Holocene that influenced glaciation. The sublimation-dominated cold-based glaciers in the northern regions of Himalayan-Tibetan orogen are more affected during these shifts in climate than the temperate glaciers in the south. (C) 2019 Elsevier Ltd. All rights reserved.}, language = {en} } @article{LiuYanZhang2019, author = {Liu, Ruo-Yu and Yan, Huirong and Zhang, Heshou}, title = {Role of Anisotropic Diffusion of Particles}, series = {Physical review letters}, volume = {123}, journal = {Physical review letters}, number = {22}, publisher = {American Physical Society}, address = {College Park}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.123.221103}, pages = {5}, year = {2019}, abstract = {In this Letter, we propose that the x-ray and the TeV observations in the vicinity of Geminga can be understood in the framework of anisotropic diffusion of injected electrons or positrons. This interpretation only requires the turbulence in the vicinity of Geminga to be sub-Alfvenic with the local mean magnetic field direction approximately aligned with our line of sight towards Geminga, without invoking extreme conditions for the environment, such as an extremely small diffusion coefficient and a weak magnetic field of submicrogauss as suggested in previous literature.}, language = {en} } @article{LeverRamelowGuehr2019, author = {Lever, Fabiano and Ramelow, Sven and G{\"u}hr, Markus}, title = {Effects of time-energy correlation strength in molecular entangled photon spectroscopy}, series = {Physical review : A, Atomic, molecular, and optical physics}, volume = {100}, journal = {Physical review : A, Atomic, molecular, and optical physics}, number = {5}, publisher = {American Physical Society}, address = {College Park}, issn = {2469-9926}, doi = {10.1103/PhysRevA.100.053844}, pages = {6}, year = {2019}, abstract = {In this paper, we explore the time-energy domain quantum-classical transition comparing a classical pump-probe experiment on a diatomic molecule to its quantum enhanced counterpart, where the pump and probe pulses are substituted by the signal and idler beams of a spontaneous parametric down conversion (SPDC) source. Absorption of biphotons generated with SPDC exploits quantum time-energy entanglement to enhance the overall yield and selectivity of the process, when compared with a classical pump-probe setup, while maintaining femtosecond time resolution. We systematically study the effects of correlation strength on process efficiency and selectivity, comparing the results to classical pump-probe spectra. An excitation scheme to improve the yield based on spectral narrowing of biphotons is shown. The results indicate that the quantum improvements in yield are caused by a more efficient use of the total power available for the process.}, language = {en} } @article{BerrahSanchezGonzalezJureketal.2019, author = {Berrah, N. and S{\´a}nchez-Gonz{\´a}lez, {\´A}lvaro and Jurek, Zoltan and Obaid, Razib and Xiong, H. and Squibb, R. J. and Osipov, T. and Lutman, A. and Fang, L. and Barillot, T. and Bozek, J. D. and Cryan, J. and Wolf, T. J. A. and Rolles, Daniel and Coffee, R. and Schnorr, Kirsten and Augustin, S. and Fukuzawa, Hironobu and Motomura, K. and Niebuhr, Nina Isabelle and Frasinski, L. J. and Feifel, Raimund and Schulz, Claus-Peter and Toyota, Kenji and Son, Sang-Kil and Ueda, K. and Pfeifer, T. and Marangos, J. P. and Santra, Robin}, title = {Femtosecond-resolved observation of the fragmentation of buckminsterfullerene following X-ray multiphoton ionization}, series = {Nature physics}, volume = {15}, journal = {Nature physics}, number = {12}, publisher = {Nature Publ. Group}, address = {London}, issn = {1745-2473}, doi = {10.1038/s41567-019-0665-7}, pages = {1279 -- 1301}, year = {2019}, abstract = {X-ray free-electron lasers have, over the past decade, opened up the possibility of understanding the ultrafast response of matter to intense X-ray pulses. In earlier research on atoms and small molecules, new aspects of this response were uncovered, such as rapid sequences of inner-shell photoionization and Auger ionization. Here, we studied a larger molecule, buckminsterfullerene (C-60), exposed to 640 eV X-rays, and examined the role of chemical effects, such as chemical bonds and charge transfer, on the fragmentation following multiple ionization of the molecule. To provide time resolution, we performed femtosecond-resolved X-ray pump/X-ray probe measurements, which were accompanied by advanced simulations. The simulations and experiment reveal that despite substantial ionization induced by the ultrashort (20 fs) X-ray pump pulse, the fragmentation of C-60 is considerably delayed. This work uncovers the persistence of the molecular structure of C-60, which hinders fragmentation over a timescale of hundreds of femtoseconds. Furthermore, we demonstrate that a substantial fraction of the ejected fragments are neutral carbon atoms. These findings provide insights into X-ray free-electron laser-induced radiation damage in large molecules, including biomolecules.}, language = {en} } @article{RuedigerSchultz2019, author = {R{\"u}diger, G{\"u}nther and Schultz, M.}, title = {Non-diffusive angular momentum transport in rotating z-pinches}, series = {Journal of plasma physics}, volume = {85}, journal = {Journal of plasma physics}, number = {6}, publisher = {Cambridge Univ. Press}, address = {New York}, issn = {0022-3778}, doi = {10.1017/S0022377819000606}, pages = {16}, year = {2019}, abstract = {The stability of conducting Taylor-Couette flows under the presence of toroidal magnetic background fields is considered. For strong enough magnetic amplitudes such magnetohydrodynamic flows are unstable against non-axisymmetric perturbations which may also transport angular momentum. In accordance with the often used diffusion approximation, one expects the angular momentum transport to be vanishing for rigid rotation. In the sense of a non-diffusive Lambda effect, however, even for rigidly rotating z-pinches, an axisymmetric angular momentum flux appears which is directed outward (inward) for large (small) magnetic Mach numbers. The internal rotation in a magnetized rotating tank can thus never be uniform. Those particular rotation laws are used to estimate the value of the instability-induced eddy viscosity for which the non-diffusive Lambda effect and the diffusive shear-induced transport compensate each other. The results provide the Shakura \& Sunyaev viscosity ansatz leading to numerical values linearly growing with the applied magnetic field.}, language = {en} } @article{SchroetterBoucheZabletal.2019, author = {Schroetter, Ilane and Bouche, Nicolas F. and Zabl, Johannes and Contini, Thierry and Wendt, Martin and Schaye, Joop and Mitchell, Peter and Muzahid, Sowgat and Marino, Raffaella Anna and Bacon, Roland and Lilly, Simon J. and Richard, Johan and Wisotzki, Lutz}, title = {MusE GAs FLOw andWind (MEGAFLOW)}, series = {Monthly notices of the Royal Astronomical Society}, volume = {490}, journal = {Monthly notices of the Royal Astronomical Society}, number = {3}, publisher = {Oxford Univ. Press}, address = {Oxford}, issn = {0035-8711}, doi = {10.1093/mnras/stz2822}, pages = {4368 -- 4381}, year = {2019}, abstract = {We present results from our on-going MusE GAs FLOw and Wind (MEGAFLOW) survey, which consists of 22 quasar lines of sight, each observed with the integral field unit MUSE and the UVES spectrograph at the ESO Very Large Telescopes (VLT). The goals of this survey are to study the properties of the circumgalactic medium around z similar to 1 star-forming galaxies. The absorption-line selected survey consists of 79 strong MgII absorbers (with rest-frame equivalent width greater than or similar to 0.3 angstrom) and, currently, 86 associated galaxies within 100 projected kpc of the quasar with stellar masses (M-star) from 109 to 1011 M-circle dot. We find that the cool halo gas traced by MgII is not isotropically distributed around these galaxies from the strong bi-modal distribution in the azimuthal angle of the apparent location of the quasar with respect to the galaxy major axis. This supports a scenario in which outflows are bi-conical in nature and co-exist with a co-planar gaseous structure extending at least up to 60-80 kpc. Assuming that absorbers near the minor axis probe outflows, the current MEGAFLOW sample allowed us to select 26 galaxy-quasar pairs suitable for studying winds. From this sample, using a simple geometrical model, we find that the outflow velocity only exceeds the escape velocity when M-star less than or similar to 4 x 10(9) M-circle dot, implying the cool material is likely to fall back except in the smallest haloes. Finally, we find that the mass loading factor., the ratio between the ejected mass rate and the star formation rate, appears to be roughly constant with respect to the galaxy mass.}, language = {en} } @misc{Goychuk2019, author = {Goychuk, Igor}, title = {Comment on "Anomalous Escape Governed by Thermal 1/f Noise" Reply (R. K. Singh)}, series = {Physical review letters}, volume = {123}, journal = {Physical review letters}, number = {23}, publisher = {American Physical Society}, address = {College Park}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.123.238902}, pages = {1}, year = {2019}, language = {en} } @article{PetitgirardSpiekermannGlazyrinetal.2019, author = {Petitgirard, Sylvain and Spiekermann, Georg and Glazyrin, Konstantin and Garrevoet, Jan and Murakami, Motohiko}, title = {Density of amorphous GeO2 to 133 GPa with possible pyritelike structure and stiffness at high pressure}, series = {Physical review : B, Condensed matter and materials physics}, volume = {100}, journal = {Physical review : B, Condensed matter and materials physics}, number = {21}, publisher = {American Physical Society}, address = {College Park}, issn = {2469-9950}, doi = {10.1103/PhysRevB.100.214104}, pages = {8}, year = {2019}, abstract = {Germanium oxide is a prototype network-forming oxide with pressure-induced structural changes similar to those found in crystals and amorphous silicate oxides at high pressure. Studying density and coordination changes in amorphous GeO2 allows for insight into structural changes in silicate oxides at very high pressure, with implications for the properties of planetary magmas. Here, we report the density of germanium oxide glass up to 133 GPa using the x-ray absorption technique, with very good agreement with previous experimental data at pressure below 40 GPa and recent calculation up to 140 GPa. Our data highlight four distinct compressibility domains, corresponding to changes of the local structure of GeO2. Above 80 GPa, our density data show a compressibility and bulk modulus similar to the counterpart crystal phase, and we propose that a compact distorted sixfold coordination, similar to the structural motif of the pyritelike crystalline GeO2 polymorph, is likely to be stable in that pressure range. Our density data point to a smooth continuous evolution of the average coordination for pressure above 20 GPa with persistent sixfold coordination, without sharp density or density slope discontinuities. These observations are in very good agreement with theoretical calculations and spectroscopic measurements, and our results indicate that glasses and melts may behave similarly to their high-pressure solid counterparts with comparable densities, compressibility, and possibly average coordination.}, language = {en} } @article{KrapfMetzler2019, author = {Krapf, Diego and Metzler, Ralf}, title = {Strange interfacial molecular dynamics}, series = {Physics today}, volume = {72}, journal = {Physics today}, number = {9}, publisher = {American Institute of Physics}, address = {Melville}, issn = {0031-9228}, doi = {10.1063/PT.3.4294}, pages = {48 -- 54}, year = {2019}, language = {en} } @article{TeichmannRosenblum2019, author = {Teichmann, Erik and Rosenblum, Michael}, title = {Solitary states and partial synchrony in oscillatory ensembles with attractive and repulsive interactions}, series = {Chaos : an interdisciplinary journal of nonlinear science}, volume = {29}, journal = {Chaos : an interdisciplinary journal of nonlinear science}, number = {9}, publisher = {American Institute of Physics}, address = {Melville}, issn = {1054-1500}, doi = {10.1063/1.5118843}, pages = {11}, year = {2019}, abstract = {We numerically and analytically analyze transitions between different synchronous states in a network of globally coupled phase oscillators with attractive and repulsive interactions. The elements within the attractive or repulsive group are identical, but natural frequencies of the groups differ. In addition to a synchronous two-cluster state, the system exhibits a solitary state, when a single oscillator leaves the cluster of repulsive elements, as well as partially synchronous quasiperiodic dynamics. We demonstrate how the transitions between these states occur when the repulsion starts to prevail over attraction.}, language = {en} } @misc{CestnikAbel2019, author = {Cestnik, Rok and Abel, Markus}, title = {Erratum: Inferring the dynamics of oscillatory systems using recurrent neural networks (Chaos : an interdisciplinary journal of nonlinear science. - 29 (2019) 063128)}, series = {Chaos : an interdisciplinary journal of nonlinear science}, volume = {29}, journal = {Chaos : an interdisciplinary journal of nonlinear science}, number = {8}, publisher = {American Institute of Physics}, address = {Melville}, issn = {1054-1500}, doi = {10.1063/1.5122803}, pages = {1}, year = {2019}, language = {en} } @article{MeyerKreplinKrausetal.2019, author = {Meyer, Dominique M.-A. and Kreplin, Alexander and Kraus, S. and Vorobyov, E. I. and Haemmerl{\´e}, Lionel and Eisl{\"o}ffel, Jochen}, title = {On the ALMA observability of nascent massive multiple systems formed by gravitational instability}, series = {Monthly notices of the Royal Astronomical Society}, volume = {487}, journal = {Monthly notices of the Royal Astronomical Society}, number = {4}, publisher = {Oxford Univ. Press}, address = {Oxford}, issn = {0035-8711}, doi = {10.1093/mnras/stz1585}, pages = {4473 -- 4491}, year = {2019}, abstract = {Massive young stellar objects (MYSOs) form during the collapse of high-mass pre-stellar cores, where infalling molecular material is accreted through a centrifugally balanced accretion disc that is subject to efficient gravitational instabilities. In the resulting fragmented accretion disc of the MYSO, gaseous clumps and low-mass stellar companions can form, which will influence the future evolution of massive protostars in the Hertzsprung-Russell diagram. We perform dust continuum radiative transfer calculations and compute synthetic images of disc structures modelled by the gravito-radiation-hydrodynamics simulation of a forming MYSO, in order to investigate the Atacama Large Millimeter/submillimeter Array (alma) observability of circumstellar gaseous clumps and forming multiple systems. Both spiral arms and gaseous clumps located at similar or equal to a few from the protostar can be resolved by interferometric alma Cycle 7 C43-8 and C43-10 observations at band 6 (), using a maximal 0.015 aracsec beam angular resolution and at least exposure time for sources at distances of . Our study shows that substructures are observable regardless of their viewing geometry or can be inferred in the case of an edge-viewed disc. The observation probability of the clumps increases with the gradually increasing efficiency of gravitational instability at work as the disc evolves. As a consequence, large discs around MYSOs close to the zero-age-main-sequence line exhibit more substructures than at the end of the gravitational collapse. Our results motivate further observational campaigns devoted to the close surroundings of the massive protostars S255IR-NIRS3 and NGC 6334I-MM1, whose recent outbursts are a probable signature of disc fragmentation and accretion variability.}, language = {en} } @article{NivenAbelSchlegeletal.2019, author = {Niven, Robert K. and Abel, Markus and Schlegel, Michael and Waldrip, Steven H.}, title = {Maximum Entropy Analysis of Flow Networks: Theoretical Foundation and Applications}, series = {Entropy}, volume = {21}, journal = {Entropy}, number = {8}, publisher = {MDPI}, address = {Basel}, issn = {1099-4300}, doi = {10.3390/e21080776}, pages = {776}, year = {2019}, abstract = {The concept of a "flow network"-a set of nodes and links which carries one or more flows-unites many different disciplines, including pipe flow, fluid flow, electrical, chemical reaction, ecological, epidemiological, neurological, communications, transportation, financial, economic and human social networks. This Feature Paper presents a generalized maximum entropy framework to infer the state of a flow network, including its flow rates and other properties, in probabilistic form. In this method, the network uncertainty is represented by a joint probability function over its unknowns, subject to all that is known. This gives a relative entropy function which is maximized, subject to the constraints, to determine the most probable or most representative state of the network. The constraints can include "observable" constraints on various parameters, "physical" constraints such as conservation laws and frictional properties, and "graphical" constraints arising from uncertainty in the network structure itself. Since the method is probabilistic, it enables the prediction of network properties when there is insufficient information to obtain a deterministic solution. The derived framework can incorporate nonlinear constraints or nonlinear interdependencies between variables, at the cost of requiring numerical solution. The theoretical foundations of the method are first presented, followed by its application to a variety of flow networks.}, language = {en} } @article{SeilerSeissHoffmannetal.2019, author = {Seiler, Michael and Seiß, Martin and Hoffmann, Holger and Spahn, Frank}, title = {Hydrodynamic Simulations of Asymmetric Propeller Structures in Saturn's Rings}, series = {The astrophysical journal : an international review of spectroscopy and astronomical physics ; Supplement series}, volume = {243}, journal = {The astrophysical journal : an international review of spectroscopy and astronomical physics ; Supplement series}, number = {2}, publisher = {IOP Publ. Ltd.}, address = {Bristol}, issn = {0067-0049}, doi = {10.3847/1538-4365/ab26b0}, pages = {16}, year = {2019}, abstract = {The observation of the non-Keplerian behavior of propeller structures in Saturn's outer A ring raises the question: how does the propeller respond to the wandering of the central embedded moonlet? Here, we study numerically how the structural imprint of the propeller changes for a libration of the moonlet. It turns out that the libration induces an asymmetry in the propeller, which depends on the libration period and amplitude of the moonlet. Further, we study the dependence of the asymmetry on the libration period and amplitude for a moonlet with a 400 m Hill radius, which is located in the outer A ring. This allows us to apply our findings to the largest known propeller Bl{\´e}riot, which is expected to be of a similar size. For Bl{\´e}riot, we can conclude that, supposing the moonlet is librating with the largest observed period of 11.1 yr and an azimuthal amplitude of about 1845 km, a small asymmetry should be measurable but depends on the moonlet's libration phase at the observation time. The longitude residuals of other trans-Encke propellers (e.g., Earhart) show amplitudes similar to Bl{\´e}riot, which might allow us to observe larger asymmetries due to their smaller azimuthal extent, allowing us to scan the whole gap structure for asymmetries in one observation. Although the librational model of the moonlet is a simplification, our results are a first step toward the development of a consistent model for the description of the formation of asymmetric propellers caused by a freely moving moonlet.}, language = {en} } @article{RichterVollhardt2006, author = {Richter, Lothar and Vollhardt, Dieter}, title = {Force measuring methods for determination of surface tension of liquids: A comparison}, series = {Tenside, surfactants, detergents}, volume = {43}, journal = {Tenside, surfactants, detergents}, number = {5}, publisher = {Hanser}, address = {M{\"u}nchen}, issn = {0932-3414}, doi = {10.3139/113.100314}, pages = {256 -- 261}, year = {2006}, abstract = {Three methods for the determination of the surface tension of liquids based on force measurements namely, the vertical plate method of Wilhelmy, the frame method of Lenard and the ring method of du Nouy are compared and studied in respect of a common principle of correction. It is shown that these three most important force-based methods allow the determination of the surface tension under static conditions. The force components of the corresponding liquid column below the measuring wire obtained for the straight part of the withdrawal curve up to the transition in its curved part provides exact surface tension values. The experimentally accessible value of the force component describes the physical background of the measured value correction contrary to the approximate equations obtained by mathematical way. Usually the determination of surface tension of liquids is based merely at the vertical plate method on exact equations thermodynamically derived whereas in the case of the frame and ring methods correction factors in approximate equations are used. At usual application of the force-based methods under the non-static condition of the withdrawal of a liquid column, the force maximum measured at withdrawal of the measuring object (plate, frame, or ring) is the basis for the determination of surface tension. In these cases, the measured surface tension values are compensated by correction equations for the frame and ring methods which are based on an correction factor and correction tables empirically obtained. The surface tension values obtained in this usual way agree with those obtained by using the force component of the corresponding liquid column below the measuring wire for the straight part of the withdrawal curve up to the transition in its curved part. Problems arising at the force measurements with increasing thickness of the measuring wires inside and outside the rings are discussed.}, language = {en} } @article{AssmannThielRomanoetal.2006, author = {Assmann, Birte and Thiel, Marco and Romano, Maria Carmen and Niemitz, Carsten}, title = {Recurrence plot analyses suggest a novel reference system involved in newborn spontaneous movements}, series = {Behavior research methods : a journal of the Psychonomic Society}, volume = {38}, journal = {Behavior research methods : a journal of the Psychonomic Society}, number = {3}, publisher = {Springer}, address = {New York}, issn = {1554-351X}, doi = {10.3758/BF03192793}, pages = {400 -- 406}, year = {2006}, abstract = {The movements of newborns have been thoroughly studied in terms of reflexes, muscle synergies, leg coordination, and target-directed arm/hand movements. Since these approaches have concentrated mainly on separate accomplishments, there has remained a clear need for more integrated investigations. Here, we report an inquiry in which we explicitly concentrated on taking such a perspective and, additionally, were guided by the methodological concept of home base behavior, which Ilan Golard developed for studies of exploratory behavior in animals. Methods from nonlinear dynamics, such as symbolic dynamics and recurrence plot analyses of kinematic data received from audiovisual newborn recordings, yielded new insights into the spatial and temporal organization of limb movements. In the framework of home base behavior, our approach uncovered a novel reference system of spontaneous newborn movements.}, language = {en} } @article{DiezTauerSchulz2006, author = {Diez, Isabel and Tauer, Klaus and Schulz, Burkhard}, title = {Unusual polymer dispersions-polypyrrole suspensions made of rings, frames, and platelets}, series = {Colloid and polymer science : official journal of the Kolloid-Gesellschaft}, volume = {284}, journal = {Colloid and polymer science : official journal of the Kolloid-Gesellschaft}, publisher = {Springer}, address = {New York}, issn = {0303-402X}, doi = {10.1007/s00396-006-1521-8}, pages = {1431 -- 1442}, year = {2006}, abstract = {Experimental results show that the polymerization of pyrrole in the presence of beta-naphthalenesulfonic acid and different fluorosurfactants like perfluorooctanesulfonic acid, perfluorooctyldiethanolamide, and ammonium perfluorooctanoate leads to polypyrrole with special morphologies, such as rings or disks and rectangular frames or plates. The formation of these unusually shaped particles of polymer dispersions is explained by the chemical and colloidal peculiarities of the oxidative pyrrole polymerization with ammonium peroxodisulfate in aqueous medium.}, language = {en} } @article{GiesersKamannDreizleretal.2019, author = {Giesers, Benjamin David and Kamann, Sebastian and Dreizler, Stefan and Husser, Tim-Oliver and Askar, Abbas and G{\"o}ttgens, Fabian and Brinchmann, Jarle and Latour, Marilyn and Weilbacher, Peter Michael and Wendt, Martin and Roth, Martin M.}, title = {A stellar census in globular clusters with MUSE: Binaries in NGC 3201}, series = {Astronomy and astrophysics : an international weekly journal}, volume = {632}, journal = {Astronomy and astrophysics : an international weekly journal}, publisher = {EDP Sciences}, address = {Les Ulis}, issn = {0004-6361}, doi = {10.1051/0004-6361/201936203}, pages = {20}, year = {2019}, abstract = {We utilise multi-epoch MUSE spectroscopy to study binary stars in the core of the Galactic globular cluster NGC 3201. Our sample consists of 3553 stars with 54 883 spectra in total comprising 3200 main-sequence stars up to 4 magnitudes below the turn-off. Each star in our sample has between 3 and 63 (with a median of 14) reliable radial velocity measurements within five years of observations. We introduce a statistical method to determine the probability of a star showing radial velocity variations based on the whole inhomogeneous radial velocity sample. Using HST photometry and an advanced dynamical MOCCA simulation of this specific cluster we overcome observational biases that previous spectroscopic studies had to deal with. This allows us to infer a binary frequency in the MUSE field of view and enables us to deduce the underlying true binary frequency of (6.75 +/- 0.72)\% in NGC 3201. The comparison of the MUSE observations with the MOCCA simulation suggests a large portion of primordial binaries. We can also confirm a radial increase in the binary fraction towards the cluster centre due to mass segregation. We discovered that in the core of NGC 3201 at least (57.5 +/- 7.9)\% of blue straggler stars are in a binary system. For the first time in a study of globular clusters, we were able to fit Keplerian orbits to a significant sample of 95 binaries. We present the binary system properties of eleven blue straggler stars and the connection to SX Phoenicis-type stars. We show evidence that two blue straggler formation scenarios, the mass transfer in binary (or triple) star systems and the coalescence due to binary-binary interactions, are present in our data. We also describe the binary and spectroscopic properties of four sub-subgiant (or red straggler) stars. Furthermore, we discovered two new black hole candidates with minimum masses (M sin i) of (7.68 +/- 0.50)M-circle dot, (4.4 +/- 2.8)M-circle dot, and refine the minimum mass estimate on the already published black hole to (4.53 +/- 0.21)M-circle dot, These black holes are consistent with an extensive black hole subsystem hosted by NGC 3201.}, language = {en} } @article{LatourHusserGiesersetal.2019, author = {Latour, Marlyn and Husser, Tim Oliver and Giesers, Benjamin David and Kamann, S. and G{\"o}ttgens, Fabian and Dreizler, Stefan and Brinchmann, Jan and Bastian, Nate and Wendt, Martin and Weilbacher, Peter Michael and Molinski, N. S.}, title = {A stellar census in globular clusters with MUSE: multiple populations chemistry in NGC 2808 star star star}, series = {Astronomy and astrophysics : an international weekly journal}, volume = {631}, journal = {Astronomy and astrophysics : an international weekly journal}, publisher = {EDP Sciences}, address = {Les Ulis}, issn = {1432-0746}, doi = {10.1051/0004-6361/201936242}, pages = {14}, year = {2019}, abstract = {Context. Galactic globular clusters (GCs) are now known to host multiple populations displaying particular abundance variations. The different populations within a GC can be well distinguished following their position in the pseudo two-colors diagrams, also referred to as "chromosome maps". These maps are constructed using optical and near-UV photometry available from the Hubble Space Telescope (HST) UV survey of GCs. However, the chemical tagging of the various populations in the chromosome maps is hampered by the fact that HST photometry and elemental abundances are both only available for a limited number of stars. Aims. The spectra collected as part of the MUSE survey of globular clusters provide a spectroscopic counterpart to the HST photometric catalogs covering the central regions of GCs. In this paper, we use the MUSE spectra of 1115 red giant branch (RGB) stars in NGC 2808 to characterize the abundance variations seen in the multiple populations of this cluster. Methods. We used the chromosome map of NGC 2808 to divide the RGB stars into their respective populations. We then combined the spectra of all stars belonging to a given population, resulting in one high signal-to-noise ratio spectrum representative of each population. Results. Variations in the spectral lines of O, Na, Mg, and Al are clearly detected among four of the populations. In order to quantify these variations, we measured equivalent width differences and created synthetic populations spectra that were used to determine abundance variations with respect to the primordial population of the cluster. Our results are in good agreement with the values expected from previous studies based on high-resolution spectroscopy. We do not see any significant variations in the spectral lines of Ca, K, and Ba. We also do not detect abundance variations among the stars belonging to the primordial population of NGC 2808. Conclusions. We demonstrate that in spite of their low resolution, the MUSE spectra can be used to investigate abundance variations in the context of multiple populations.}, language = {en} } @article{FoxRichterAshleyetal.2019, author = {Fox, Andrew J. and Richter, Philipp and Ashley, Trisha and Heckman, Timothy M. and Lehner, Nicolas and Werk, Jessica K. and Bordoloi, Rongmon and Peeples, Molly S.}, title = {The Mass Inflow and Outflow Rates of the Milky Way}, series = {The astrophysical journal : an international review of spectroscopy and astronomical physics}, volume = {884}, journal = {The astrophysical journal : an international review of spectroscopy and astronomical physics}, number = {1}, publisher = {IOP Publ. Ltd.}, address = {Bristol}, issn = {0004-637X}, doi = {10.3847/1538-4357/ab40ad}, pages = {7}, year = {2019}, abstract = {We present new calculations of the mass inflow and outflow rates around the Milky Way (MW), derived from a catalog of ultraviolet metal-line high-velocity clouds (HVCs). These calculations are conducted by transforming the HVC velocities into the Galactic standard of rest (GSR) reference frame, identifying inflowing (vGSR.<.0 km s(-1)) and outflowing (vGSR > 0 km s(-1)) populations, and using observational constraints on the distance, metallicity, dust content, covering fractions, and total silicon column density of each population. After removing HVCs associated with the Magellanic Stream and the Fermi Bubbles, we find inflow and outflow rates in cool (T similar to 10(4) K) ionized gas of dM(in)/dt greater than or similar to.(0.53 +/- 0.23)(d/12 kpc)(Z/0.2Z(circle dot))-1M(circle dot) yr(-1) and dM(out)/dt greater than or similar to (0.16 +/- 0.07)(d/12 kpc)(Z/0.5Z(circle dot))M--1(circle dot) yr(-1). The apparent excess of inflowing over outflowing gas suggests that the MW is currently in an inflow-dominated phase, but the presence of substantial mass flux in both directions supports a Galactic fountain model, in which gas is constantly recycled between the disk and the halo. We also find that the metal flux in both directions (in and out) is indistinguishable. By comparing the outflow rate to the Galactic star formation rate, we present the first estimate of the mass loading factor (eta(HVC)) of the disk-wide MW wind, finding eta(HVC) greater than or similar to (0.10 +/- 0.06)(d/12 kpc)(Z/0.5Z(circle dot))(-1). Including the contributions from low- and intermediatevelocity clouds and from hot gas would increase these inflow and outflow estimates.}, language = {en} } @article{MeiKochovskiRoaetal.2019, author = {Mei, Shilin and Kochovski, Zdravko and Roa, Rafael and Gu, Sasa and Xu, Xiaohui and Yu, Hongtao and Dzubiella, Joachim and Ballauff, Matthias and Lu, Yan}, title = {Enhanced Catalytic Activity of Gold@Polydopamine Nanoreactors with Multi-compartment Structure Under NIR Irradiation}, series = {Nano-Micro Letters}, volume = {11}, journal = {Nano-Micro Letters}, number = {1}, publisher = {Shanghai JIAO TONG univ press}, address = {Shanghai}, issn = {2311-6706}, doi = {10.1007/s40820-019-0314-9}, pages = {16}, year = {2019}, abstract = {Photothermal conversion (PTC) nanostructures have great potential for applications in many fields, and therefore, they have attracted tremendous attention. However, the construction of a PTC nanoreactor with multi-compartment structure to achieve the combination of unique chemical properties and structural feature is still challenging due to the synthetic difficulties. Herein, we designed and synthesized a catalytically active, PTC gold (Au)@polydopamine (PDA) nanoreactor driven by infrared irradiation using assembled PS-b-P2VP nanosphere as soft template. The particles exhibit multi-compartment structure which is revealed by 3D electron tomography characterization technique. They feature permeable shells with tunable shell thickness. Full kinetics for the reduction reaction of 4-nitrophenol has been investigated using these particles as nanoreactors and compared with other reported systems. Notably, a remarkable acceleration of the catalytic reaction upon near-infrared irradiation is demonstrated, which reveals for the first time the importance of the synergistic effect of photothermal conversion and complex inner structure to the kinetics of the catalytic reduction. The ease of synthesis and fresh insights into catalysis will promote a new platform for novel nanoreactor studies.}, language = {en} } @article{SahaOwenOrretal.2019, author = {Saha, Sourav and Owen, Lewis A. and Orr, Elizabeth N. and Caffee, Marc W.}, title = {Cosmogenic Be-10 and equilibrium-line altitude dataset of Holocene glacier advances in the Himalayan-Tibetan orogen}, series = {Data in brief}, volume = {26}, journal = {Data in brief}, publisher = {Elsevier}, address = {Amsterdam}, issn = {2352-3409}, doi = {10.1016/j.dib.2019.104412}, pages = {13}, year = {2019}, abstract = {A comprehensive analysis of the variable temporal and spatial responses of tropical-subtropical high-altitude glaciers to climate change is critical for successful model predictions and environmental risk assessment in the Himalayan-Tibetan orogen. High-frequency Holocene glacier chronostratigraphies are therefore reconstructed in 79 glaciated valleys across the orogen using 519 published and 16 new terrestrial cosmogenic 10Be exposure age dataset. Published 10Be ages are compiled only for moraine boulders (excluding bedrock ages). These ages are recalculated using the latest ICE-D production rate calibration database and the scaling scheme models. Outliers for the individual moraine are detected using the Chauvenet's criterion. In addition, past equilibrium-line altitudes (ELAs) are determined using the area-altitude (AA), area accumulation ratio (AAR), and toe-headwall accumulation ratio (THAR) methods for each glacier advance. The modern maximum elevations of lateral moraines (MELM) are also used to estimate modern ELAs and as an independent check on mean ELAs derived using the above three methods. These data may serve as an essential archive for future studies focusing on the cryospheric and environmental changes in the Himalayan-Tibetan orogen. A more comprehensive analysis of the published and new 10Be ages and ELA results and a list of references are presented in Saha et al. (2019, High-frequency Holocene glacier fluctuations in the Himalayan-Tibetan orogen. Quaternary Science Reviews, 220, 372-400).}, language = {en} } @article{TeomyMetzler2019, author = {Teomy, Eial and Metzler, Ralf}, title = {Transport in exclusion processes with one-step memory: density dependence and optimal acceleration}, series = {Journal of physics : A, Mathematical and theoretical}, volume = {52}, journal = {Journal of physics : A, Mathematical and theoretical}, number = {38}, publisher = {IOP Publ. Ltd.}, address = {Bristol}, issn = {1751-8113}, doi = {10.1088/1751-8121/ab37e4}, pages = {19}, year = {2019}, abstract = {We study a lattice gas of persistent walkers, in which each site is occupied by at most one particle and the direction each particle attempts to move to depends on its last step. We analyse the mean squared displacement (MSD) of the particles as a function of the particle density and their persistence (the tendency to continue moving in the same direction). For positive persistence the MSD behaves as expected: it increases with the persistence and decreases with the density. However, for strong anti-persistence we find two different regimes, in which the dependence of the MSD on the density is non-monotonic. For very strong anti-persistence there is an optimal density at which the MSD reaches a maximum. In an intermediate regime, the MSD as a function of the density exhibits both a minimum and a maximum, a phenomenon which has not been observed before. We derive a mean-field theory which qualitatively explains this behaviour.}, language = {en} } @article{PalyulinBlackburnLomholtetal.2019, author = {Palyulin, Vladimir V. and Blackburn, George and Lomholt, Michael A. and Watkins, Nicholas W. and Metzler, Ralf and Klages, Rainer and Chechkin, Aleksei V.}, title = {First passage and first hitting times of Levy flights and Levy walks}, series = {New journal of physics : the open-access journal for physics}, volume = {21}, journal = {New journal of physics : the open-access journal for physics}, number = {10}, publisher = {IOP Publ. Ltd.}, address = {Bristol}, issn = {1367-2630}, doi = {10.1088/1367-2630/ab41bb}, pages = {23}, year = {2019}, abstract = {For both L{\´e}vy flight and L{\´e}vy walk search processes we analyse the full distribution of first-passage and first-hitting (or first-arrival) times. These are, respectively, the times when the particle moves across a point at some given distance from its initial position for the first time, or when it lands at a given point for the first time. For L{\´e}vy motions with their propensity for long relocation events and thus the possibility to jump across a given point in space without actually hitting it ('leapovers'), these two definitions lead to significantly different results. We study the first-passage and first-hitting time distributions as functions of the L{\´e}vy stable index, highlighting the different behaviour for the cases when the first absolute moment of the jump length distribution is finite or infinite. In particular we examine the limits of short and long times. Our results will find their application in the mathematical modelling of random search processes as well as computer algorithms.}, language = {en} } @article{TeomyMetzler2019, author = {Teomy, Eial and Metzler, Ralf}, title = {Correlations and transport in exclusion processes with general finite memory}, series = {Journal of statistical mechanics: theory and experiment}, volume = {2019}, journal = {Journal of statistical mechanics: theory and experiment}, number = {10}, publisher = {IOP Publ. Ltd.}, address = {Bristol}, issn = {1742-5468}, doi = {10.1088/1742-5468/ab47fb}, pages = {31}, year = {2019}, language = {en} } @article{KurzkeKietheHeueretal.2017, author = {Kurzke, Henning and Kiethe, Jan and Heuer, Axel and Jechow, Andreas}, title = {Frequency doubling of incoherent light from a superluminescent diode in a periodically poled lithium niobate waveguide crystal}, series = {Laser physics letters}, volume = {14}, journal = {Laser physics letters}, publisher = {IOP Publ.}, address = {Bristol}, issn = {1612-2011}, doi = {10.1088/1612-202X/aa6889}, pages = {5}, year = {2017}, abstract = {The amplified spontaneous emission from a superluminescent diode was frequency doubled in a periodically poled lithium niobate waveguide crystal. The temporally incoherent radiation of such a superluminescent diode is characterized by a relatively broad spectral bandwidth and thermal-like photon statistics, as the measured degree of second order coherence, g((2))(0)= 1.9 +/- 0.1, indicates. Despite the non-optimized scenario in the spectral domain, we achieve six orders of magnitude higher conversion efficiency than previously reported with truly incoherent light. This is possible by using single spatial mode radiation and quasi phase matched material with a waveguide architecture. This work is a principle step towards efficient frequency conversion of temporally incoherent radiation in one spatial mode to access wavelengths where no radiation from superluminescent diodes is available, especially with tailored quasi phase matched crystals. The frequency doubled light might find application in imaging, metrology and quantum optics experiments.}, language = {en} } @phdthesis{Schmoll2001, author = {Schmoll, J{\"u}rgen}, title = {3D-Spektrofotometrie extragalaktischer Emissionslinienobjekte}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-0000372}, school = {Universit{\"a}t Potsdam}, year = {2001}, abstract = {Popul{\"a}rwissenschaftlicher Abstract: Bislang gibt es in der beobachtenden optischen Astronomie zwei verschiedene Herangehensweisen: Einerseits werden Objekte durch Kameras abbildend erfaßt, andererseits werden durch die wellenl{\"a}ngenabh{\"a}ngige Zerlegung ihres Lichtes Spektren gewonnen. Das Integral - Field - Verfahren ist eine relativ neue Technik, welche die genannten Beobachtungsmethoden vereint. Das Objektbild im Teleskopfokus wird in r{\"a}umlich zerlegt und jedes Ortselement einem gemeinsamen Spektrografen zugef{\"u}hrt. Hierdurch wird das Objekt nicht nur zweidimensional r{\"a}umlich erfaßt, sondern zus{\"a}tzlich die spektrale Kompenente als dritte Dimension erhalten, weswegen das Verfahren auch als 3D-Methode bezeichnet wird. Anschaulich kann man sich das Datenresultat als eine Abbildung vorstellen, in der jeder einzelne Bildpunkt nicht mehr nur einen Intensit{\"a}tswert enth{\"a}lt, sondern gleich ein ganzes Spektrum. Diese Technik erm{\"o}glicht es, ausgedehnte Objekte im Unterschied zu g{\"a}ngigen Spaltspektrografen komplett zu erfassen. Die besondere St{\"a}rke der Methode ist die M{\"o}glichkeit, die Hintergrundkontamination der unmittelbaren Umgebung des Objektes zu erfassen und in der Auswertung zu ber{\"u}cksichtigen. Durch diese F{\"a}higkeit erscheint die 3D-Methode pr{\"a}destiniert f{\"u}r den durch moderne Großteleskope erschlossenen Bereich der extragalaktischen Stellarastronomie. Die detaillierte Untersuchung aufgel{\"o}ster stellare Populationen in nahegelegenen Galaxien ist erst seit kurzer Zeit dank der Fortschritte mit modernen Grossteleskopen und fortschrittlicher Instrumentierung m{\"o}glich geworden. Wegen der Bedeutung f{\"u}r die Entstehung und Evolution von Galaxien werden diese Arbeiten zuk{\"u}nftig weiter an Bedeutung gewinnen. In der vorliegenden Arbeit wurde die Integral-Field-Spektroskopie an zwei planetarischen Nebeln in der n{\"a}chstgelegenen großen Spiralgalaxie M31 (NGC 224) getestet, deren Helligkeiten und Koordinaten aus einer Durchmusterung vorlagen. Hierzu wurden Beobachtungen mit dem MPFS-Instrument am russischen 6m - Teleskop in Selentschuk/Kaukasus sowie mit INTEGRAL/WYFFOS am englischen William-Herschel-Teleskop auf La Palma gewonnen. Ein {\"u}berraschendes Ergebnis war, daß eins der beiden Objekte falsch klassifiziert wurde. Sowohl die meßbare r{\"a}umliche Ausdehnung des Objektes als auch das spektrale Erscheinungsbild schlossen die Identit{\"a}t mit einem planetarischen Nebel aus. Mit hoher Wahrscheinlichkeit handelt es sich um einen Supernova{\"u}berrest, zumal im Rahmen der Fehler an gleicher Stelle eine vom R{\"o}ntgensatelliten ROSAT detektierte R{\"o}ntgenquelle liegt. Die in diesem Projekt verwendeten Integral-Field-Instrumente wiesen zwei verschiedene Bauweisen auf, die sich miteinander vergleichen ließen. Ein Hauptkritikpunkt der verwendeten Instrumente war ihre geringe Lichtausbeute. Die gesammelten Erfahrung fanden Eingang in das Konzept des derzeit in Potsdam in der Fertigung befindlichen 3D-Instruments PMAS (Potsdamer Multi - Apertur - Spektrophotometer), welcher zun{\"a}chst f{\"u}r das 3.5m-Teleskop des Calar - Alto - Observatoriums in S{\"u}dspanien vorgesehen ist. Um die Effizienz dieses Instrumentes zu verbessern, wurde in dieser Arbeit die Kopplung der zum Bildrasterung verwendeten Optik zu den Lichtleitfasern im Labor untersucht. Die Untersuchungen zur Maximierung von Lichtausbeute und Stabilit{\"a}t zeigen, daß sich die Effizienz durch Auswahl einer geeigneten Koppelmethode um etwa 20 Prozent steigern l{\"a}sst.}, language = {de} }