Parameter-induced uncertainty quantification of soil N 2 O, NO and CO 2 emission from Höglwald spruce forest (Germany) using the LandscapeDNDC model

Assessing the uncertainties of simulation results of ecological models is becoming increasingly important, specifically if these models are used to estimate greenhouse gas emissions on site to regional/national levels. Four general sources of uncertainty effect the outcome of process-based models: (i) uncertainty of information used to initialise and drive the model, (ii) uncertainty of model parameters describing specific ecosystem processes, (iii) uncertainty of the model structure, and (iv) accurateness of measurements (e.g., soil-atmosphere greenhouse gas exchange) which are used for model testing and development. The aim of our study was to assess the simulation uncertainty of the process-based biogeochemical model LandscapeDNDC. For this we set up a Bayesian framework using a Markov Chain Monte Carlo (MCMC) method, to estimate the joint model parameter distribution. Data for model testing, parameter estimation and uncertainty assessment were taken from observations of soil fluxes of nitrous oxide (N2O), nitric oxide (NO) and carbon dioxide (CO2) as observed over a 10 yr period at the spruce site of the Höglwald Forest, Germany. By running four independent Markov Chains in parallel with identical properties (except for the parameter start values), an objective criteria for chain convergence developed by Gelman et al. (2003) could be used. Our approach shows that by means of the joint parameter distribution, we were able not only to limit the parameter space and specify the probability of parameter values, but also to assess the complex dependencies among model parameters used for simulating soil C and N trace gas emissions. This helped to improve the understanding of the behaviour of the complex LandscapeDNDC model while simulating soil C and N turnover processes and associated C and N soil-atmosphere exchange. In a final step the parameter distribution of the most sensitive parameters determining soil-atmosphere C and N exchange were used to obtain the parameter-induced uncertainty of simulated N2O, NO and CO2 emissions. These were compared to observational data of an calibration set (6 yr) and an independent validation set of 4 yr. The comparison showed that most of the annual observed trace gas emissions were in the range of simulated values and were predicted with a high certainty (Root-mean-squared error (RMSE) NO: 2.4 to 18.95 g N ha−1 d−1, N2O: 0.14 to 21.12 g N ha−1 d−1, CO2: 5.4 to 11.9 kg C ha−1 d−1). However, LandscapeDNDC simulations were sometimes still limited to accurately predict observed seasonal variations in fluxes

Kratkoročni učinci prirodnog protoka na kvalitetu vode duž dva urbana potoka – pilot-istraživanje

In this pilot-study, we investigated the short-term effects of natural stream discharge on the stream water quality at six sites located along the two urban streams - Bliznec (B) and Veliki potok (VP) - flowing through Zagreb, capital of Croatia. The streams source within the Medvednica Nature Park (upper stream reaches) and flow along an increasing urban gradient in central Zagreb region (middle and lower stream reaches). The following physico-chemical parameters were measured every other day over the two-week period in October 2017: stream discharge, water temperature and oxygen concentration, conductivity, pH, chemical oxygen demand (CODKMnO4), and in-stream concentrations of nutrients (nitrites, nitrates, orthophosphates). Nutrients were the most variable parameters during the two-week period. Bliznec generally showed significantly higher discharge and oxygen levels compared to Veliki potok, which had significantly higher CODKMnO4 and nitrite concentrations. Middle and lower stream reaches had significantly higher temperature, nitrite and nitrate concentrations in comparison to the upper reaches. Several physico-chemical parameters (discharge, nitrites, nitrates, orthophosphates, conductivity and CODKMnO44) evidenced to be highly synchronized between the two streams, among the three stream reaches and among the six sites over time, which was corroborated by relatively high proxy for temporal concordance (τ > 0.60) of these parameters. This indicated that environmental conditions (stream water quality) synchronously vary across space and over time along our study streams. The data also revealed significant between-site and temporal changes of the physico-chemical parameters after a major storm event. Moreover, conductivity was found to correlate with discharge. Findings of the present pilot study indicate that urban streams are very dynamic ecosystems showing an increased sensitivity to environmental changes, such as anthropogenic influences and local weather conditions. We suggest that the extensive environmental variability of urban streams should be considered in the scope of ecological studies and environmental management approaches within urban zones.U ovom pilot-istraživanju istražili smo kratkoročne učinke prirodnog protoka na kakvoću vode na šest postaja smještenih duž dva urbana potoka - Blizneca (B) i Velikog potoka (VP) - koji protječu kroz Zagreb, glavni grad Hrvatske. Potoci izviru unutar Parka prirode Medvednica (gornji tok) i teku duž rastućeg urbanog gradijenta, kroz središnji dio Zagreba (srednji i donji tok). Svaki drugi dan tijekom dva tjedna u listopadu 2017. mjereni su sljedeći fizičko-kemijski parametri za vodu: protok, temperatura vode i koncentracija kisika, konduktivitet, pH, kemijska potrošnja kisika (KPKKMnO4) i koncentracija hranjivih soli (nitrita, nitrata, ortofosfata) u vodi. Najvarijabilniji parametri tijekom dva tjedna bile su koncentracije hranjivih soli. Bliznec je općenito pokazao značajno više vrijednosti protoka i koncentracije kisika u odnosu na Veliki potok, koji je imao značajno više vrijednosti KPKKMnO4 i koncentracije nitrita. Srednji i donji dijelovi toka oba potoka imali su značajno više temperature te koncentracije nitrita i nitrata u odnosu na gornji tok. Nekoliko fizičko-kemijskih parametara (protok, koncentracije nitrita, nitrata i ortofosfata, konduktivitet i KPKKMnO4) pokazali su veliku podudarnost vremenskih trendova između dva potoka, između tri dijela toka i između šest postaja, što je i dokazano relativno visokim koeficijentom (τ > 0.60) koji ukazuje na vremensko podudaranje parametara. To je nadalje ukazalo da se okolišni uvjeti (kakvoća vode) duž naših potoka ujednačeno mijenjaju u prostoru i vremenu. Podaci su također ukazali na značajne promjene mjerenih fizikalno-kemijskih parametara nakon nevremena (razdoblja povišenog protoka vode). Nadalje, korelacijskom analizom je utvrđeno da konduktivitet značajno ovisi o protoku. Rezultati ovog pilot-istraživanja pokazuju da su urbani potoci vrlo dinamični ekosustavi koji pokazuju povećanu osjetljivost na promjene u okolišu, kao što su antropogeni utjecaji i lokalni vremenski uvjeti. Predlažemo da se u okviru ekoloških studija i pri upravljanju okolišem unutar urbanih zona uzme u obzir značajna ekološka varijabilnost urbanih vodotoka

Spectral analysis of the sdO K 648, the exciting star of the planetary nebula Ps 1 in the globular cluster M 15 (NGC 7078)

We present a spectral analysis of the sdO central star K 648 based on medium-resolution optical and high-resolution UV spectra. The photospheric parameters are determined by means of state-of-the-art NLTE model atmosphere techniques. We found Teff = 39 +/- 2 kK and log g = 3.9 +/- 0.2. The helium (He/H=0.08) and oxygen (O/H=0.001) abundances are about solar while carbon is enriched by a factor of 2.5 (C/H=0.001). Nitrogen (N/H = 10**(-6), [N/H] = -2.0) appears at a sub-solar value. However, these metal abundances are much higher than the cluster's metallicity M 15: [Fe/H] = -2.25). The surface composition appears to be a mixture of the original hydrogen-rich material and products of helium burning (3 alpha process) which have been mixed up to the surface. The abundances of He, C, and N are consistent with the nebular abundance, while O is considerably more abundant in the photosphere than in the nebula. From a comparison of its position in the log Teff - log g plane with evolutionary calculations a mass of 0.57 (+0.02, -0.01) Msun and a luminosity of 3810 +/- 1200 Lsun are deduced. Our spectroscopic distance d = 11.1 (+2.4, -2.9) kpc is in agreement with the distance of M 15 as determined by Alves et al. (2000). From the GHRS spectra we measure a radial velocity of vrad = -130 km/sec.Comment: 8 pages, 13 figure

Quantifying the anisotropy in the infrared emission of powerful AGN

We use restframe near- and mid-IR data of an isotropically selected sample of quasars and radio galaxies at 1.0 \leq z \leq 1.4, which have been published previously, to study the wavelength-dependent anisotropy of the IR emission. For that we build average SEDs of the quasar subsample (= type 1 AGN) and radio galaxies (= type 2 AGN) from ~1-17 {\mu}m and plot the ratio of both average samples. From 2 to 8 {\mu}m restframe wavelength the ratio gradually decreases from 20 to 2 with values around 3 in the 10{\mu}m silicate feature. Longward of 12{\mu}m the ratio decreases further and shows some high degree of isotropy at 15 {\mu}m (ratio ~1.4). The results are consistent with upper limits derived from the X-ray/mid-IR correlation of local Seyfert galaxies. We find that the anisotropy in our high-luminosity radio-loud sample is smaller than in radio-quiet lower-luminosity AGN which may be interpreted in the framework of a receding torus model with luminosity-dependent obscuration properties. It is also shown that the relatively small degree of anisotropy is consistent with clumpy torus models.Comment: 6 pages, 2 figures; accepted by Ap

Актуализация принципов планирования деятельности предприятия

Рассматриваются вопросы развития некоторых принципов планирования показателей деятельности предприятий в контексте современной парадигмы менеджмента, дается характеристика принципов планирования и условий их применения

Human-Robotic Variable-Stiffness Grasps of Small-Fruit Containers Are Successful Even Under Severely Impaired Sensory Feedback

Application areas of robotic grasping extend to delicate objects like groceries. The intrinsic elasticity offered by variable-stiffness actuators (VSA) appears to be promising in terms of being able to adapt to the object shape, to withstand collisions with the environment during the grasp acquisition, and to resist the weight applied to the fingers by a lifted object during the actual grasp. It is hypothesized that these properties are particularly useful in the absence of high-quality sensory feedback, which would otherwise be able to guide the shape adaptation and collision avoidance, and that in this case, VSA hands perform better than hands with fixed stiffness. This hypothesis is tested in an experiment where small-fruit containers are picked and placed using a newly developed variable-stiffness robotic hand. The grasp performance is measured under different sensory feedback conditions: full or impaired visual feedback, full or impaired force feedback. The hand is switched between a variable-stiffness mode and two fixed-stiffness modes. Strategies for modulating the stiffness and exploiting environmental constraints are observed from human operators that control the robotic hand. The results show consistently successful grasps under all stiffness and feedback conditions. However, the performance is affected by the amount of available visual feedback. Different stiffness modes turn out to be beneficial in different feedback conditions and with respect to different performance criteria, but a general advantage of VSA over fixed stiffness cannot be shown for the present task. Guidance of the fingers along cracks and gaps is observed, which may inspire the programming of autonomously grasping robots

Innovation durch Kooperation - Analyse handelsüblicher Radialdichtelemente und Entwicklung einer neuen Bauform mit erweiterten Leistungsgrenzen

In vielen Bereichen der Technik sind Fluide unter Druck bei gleichzeitig hoher Gleitgeschwindigkeit zuverlässig abzudichten. Alternativ zu den verhältnismäßig teuren, komplexen und groß bauenden Axial-Gleitringdichtungen werden für Drücke kleiner 1 MPa preisgünstige, klein bauende Polymer-Radialdichtungen angeboten. Steigende Leistungsanforderungen hinsichtlich Druck und Gleitgeschwindigkeit führen dazu, daß die Einsatzgrenzen diese Dichtelemente überschritten werden. Am Institut für Maschinenelemente der Universität Stuttgart wurde ein Dichtsystem mit einem neuen Funktionsprinzip entwickelt. Der 'Entlastete Wellendichtring' hat ein wesentlich erweitertes Leistungsspektrum. Durch die enge Zusammenarbeit mit der Merkel Freudenberg Fluidtechnic, Hamburg, liegt jetzt ein praxisreifes, fertigungs- und montagetechnisch optimiertes, innovatives Dichtelement vor

Was ist Elite?

Was bedeutet wissenschaftliche »Exzellenz« an Universitäten in Deutschland? Wir nähern uns dieser Frage, indem wir anhand empirischer Daten untersuchen, wie Medien einerseits und Studierende andererseits die Zuerkennung wissenschaftlicher »Elite« und »Exzellenz« deuten. Dabei betrachten wir den Übergang zu einer Exzellenzuniversität als unprogrammierte »Statuspassage«. Da die Konzepte »Elite« und »Exzellenz« hinsichtlich ihrer Bedeutungen und Konsequenzen unterbestimmt sind, sind Akteure, die die Statuspassage zur »Exzellenz« betreten, entsprechend unsicher in der Deutung dieser Passage. Sie entwickeln heterogene Strategien, um mit dieser Unsicherheit umzugehen, gleichen sich jedoch dahingehend, dass sie außerwissenschaftliche Deutungsschemata mobilisieren, um wissenschaftliche »Exzellenz« erklärbar und einschätzbar zu machen. Während diese Deutungsmuster den Medien (und Universitätsrepräsentanten) dazu dienen, das Exzellenzetikett der Universität zu legitimieren – etwa mittels Mythologisierungen –, stehen studentische Deutungen der Statuspassage dazu in einem auffälligen Spannungsverhältnis: Ambivalenzen, Unwissenheit und Fatalisierungen kennzeichnen studentische Strategien der Identifizierung mit der neuerdings exzellenten Universität. What does scientific »excellence« mean at German universities? In this paper we analyze this question on the basis of empirical data and show how both the media and students interpret the nomination of »elite« universities. We regard the transition to an »elite« university as an unfamiliar »status passage«. The meanings and consequences of the terms »elite« and »excellence« are undefined so actors have problems and are uncertain when interpreting the new status passage. They develop heterogeneous strategies in order to cope with this uncertainty. Both actorgroups use non-scientific categories to explicate and assess scientific »excellence«. Whereas the media (and representatives of the university) use these categories to legitimize the new »elite« label – e.g., by converting it into a myth – students react very differently: Their coping strategies can be characterized as ambivalent, ignorant, and fatalistic

Clustering of red galaxies around the z=1.53 quasar 3C270.1

In the paradigm of hierarchical galaxy formation, luminous radio galaxies mark mass assembly peaks that should contain clusters of galaxies. Observations of the z=1.53 quasar 3C270.1 with the Spitzer Space Telescope at 3.6-24 micron and with the 6.5-m MMT in the z'- and Y-bands allow detection of potential cluster members via photometric redshifts. Compared with nearby control fields, there is an excess of 11 extremely red objects (EROs) at 1.33 < z_phot < 1.73, consistent with a proto-cluster around the quasar. The spectral energy distributions (SEDs) of 3/4 of the EROs are better fitted with passive elliptical galaxies than withdust-reddened starbursts, and of four sources well-detected on an archival HST snapshot image, all have undisturbed morphologies. However, one ERO, not covered by the HST image, is a double source with 0.8" separation on the z' image and a marginal (2sigma) 24 micron detection indicating a dust-enshrouded starburst. The EROs are more luminous than L* (H = -23.6 AB mag at z=1.5).Comment: 12 pages, 7 figures, accepted by Ap