Microsimulation of urban land use

The project ILUMASS (Integrated Land-Use Modelling and Transportation System Simulation) aims at embedding a microscopic dynamic simulation model of urban traffic flows into a comprehensive model system incorporating both changes of land use and the resulting changes in transport demand. The land-use component of ILUMASS will be based on the land-use parts of an existing urban simulation model, but is to be microscopic like the transport parts of ILUMASS. Microsimulation modules will include models of demographic development, household formation, firm lifecycles, residential and non-residential construction, labour mobility on the regional labour market and household mobility on the regional housing market. These modules will be closely linked with the models of daily activity patterns and travel and goods movements modelled in the transport parts of ILUMASS developed by other partners of the project team. The design of the land use model takes into account that the collection of individual micro data (i.e. data which because of their micro location can be associated with individual buildings or small groups of buildings) or the retrieval of individual micro data from administrative registers for planning purposes is neither possible nor, for privacy reasons, desirable. The land use model therefore works with synthetic micro data which can be retrieved from generally accessible public data. ILUMASS is a group project of institutes of the universities of Aachen, Bamberg, Dortmund, Cologne and Wuppertal under the co-ordination of the Transport Research Institute of the German Aerospace Centre (DLR). Study region for tests and first applications of the model is the urban region of Dortmund. The common database will be compiled in co-operation with the City of Dortmund. After its completion the integrated model is to be used for assessing the impacts of potential transport and land use policies for the new land use plan of the city. The paper will focus on the land-use parts of the ILUMASS model. It will present the underlying behavioural theories and how they are made operational in the model design, explain how the synthetic population is generated, show first model results and demonstrate the potential usefulness of the model for the planning process.

Interaction Quench in the Hubbard model

Motivated by recent experiments in ultracold atomic gases that explore the nonequilibrium dynamics of interacting quantum many-body systems, we investigate the opposite limit of Landau's Fermi liquid paradigm: We study a Hubbard model with a sudden interaction quench, that is the interaction is switched on at time t=0. Using the flow equation method, we are able to study the real time dynamics for weak interaction U in a systematic expansion and find three clearly separated time regimes: i) An initial buildup of correlations where the quasiparticles are formed. ii) An intermediate quasi-steady regime resembling a zero temperature Fermi liquid with a nonequilibrium quasiparticle distribution function. iii) The long time limit described by a quantum Boltzmann equation leading to thermalization with a temperature T proportional to U.Comment: Final version as publishe

Exploiting the nonlinear impact dynamics of a single-electron shuttle for highly regular current transport

The nanomechanical single-electron shuttle is a resonant system in which a suspended metallic island oscillates between and impacts at two electrodes. This setup holds promise for one-by-one electron transport and the establishment of an absolute current standard. While the charge transported per oscillation by the nanoscale island will be quantized in the Coulomb blockade regime, the frequency of such a shuttle depends sensitively on many parameters, leading to drift and noise. Instead of considering the nonlinearities introduced by the impact events as a nuisance, here we propose to exploit the resulting nonlinear dynamics to realize a highly precise oscillation frequency via synchronization of the shuttle self-oscillations to an external signal.Comment: 5 pages, 4 figure

Estimating Grassland Biomass - Potentials and Limitations of Point Cloud Analysis

Quantifying above ground biomass of grasslands is important information for grassland management and the understanding of ecological processes in grassland habitats. Often, allometric relationships between grassland height and biomass are used for biomass estimation. While these methods may be used in intensively used grassland with a homogenous canopy surface, in heterogenous grasslands it is not possible to repeat these measurements on larger areas. Recent technological advances in active and passive remote sensing offering new opportunities for estimations of grassland biomass. Many studies using remote sensing data for biomass estimation are based on the analysis of optical remote sensing sensors and are situated in forests and agricultural crops. Small temporal and spatially heterogenous grasslands were often neglected due to their complex vegetation structure. Just recently, point cloud data based either on terrestrial laser measurements (TLS) or on photogrammetric image analysis (SfM) approaches were investigated for their potential of biomass estimation in grasslands. The focus of this talk will be on evaluating the potential of TLS and SfM derived point clouds in deriving biomass estimation of grasslands with very different land use intensities. Both approaches show promising results for predicting grassland biomass (R2 ranging from 0.48 to 0.79 and from 0.35 to 0.81 for TLS and SfM respectively). TLS always performs better, which could be explained by the higher point densities and thus higher information content about the vegetation structure. However, under consideration of price and expert knowledge UAV based point clouds also produce satisfying results. Another aspect of the talk will be the comparison of performance aspects (e.g. computing time) of different point cloud analysis strategies. It can be shown that two scans of the same location from different aspects already provide detailed information about biomass and additional scans only lead to an unnecessary increase in data volume while maintaining consistent prediction quality. Various analysis methods will be test for extracting information from the point clouds. Here methods based on canopy surface height show the best prediction performance for biomass. Concluding, it is possible to say that both TLS and SfM-based point clouds have a good potential for deriving biomass information of grasslands, independent of land use intensity. However, to derive final conclusions the stability of the statistical relationships needs to be test over several growing periods. For the future, also the fusion of point cloud information with spectral information should be tested, as better biomass prediction models can be expected from this

implementation of an in-house management routine

Background Coma of unknown origin is an emergency caused by a variety of possibly life-threatening pathologies. Although lethality is high, there are currently no generally accepted management guidelines. Methods We implemented a new interdisciplinary standard operating procedure (SOP) for patients presenting with non-traumatic coma of unknown origin. It includes a new in- house triage process, a new alert call, a new composition of the clinical response team and a new management algorithm (altogether termed “coma alarm”). It is triggered by two simple criteria to be checked with out-of-hospital emergency response teams before the patient arrives. A neurologist in collaboration with an internal specialist leads the in-hospital team. Collaboration with anaesthesiology, trauma surgery and neurosurgery is organised along structured pathways that include standardised laboratory tests and imaging. Patients were prospectively enrolled. We calculated response times as well as sensitivity and false positive rates, thus proportions of over- and undertriaged patients, as quality measures for the implementation in the SOP. Results During 24 months after implementation, we identified 325 eligible patients. Sensitivity was 60 % initially (months 1–4), then fluctuated between 84 and 94 % (months 5–24). Overtriage never exceeded 15 % and undertriage could be kept low at a maximum of 11 % after a learning period. We achieved a median door-to-CT time of 20 minutes. 85 % of patients needed subsequent ICU treatment, 40 % of which required specialised neuro- ICUs. Discussion Our results indicate that our new simple in-house triage criteria may be sufficient to identify eligible patients before arrival. We aimed at ensuring the fastest possible proceedings given high portions of underlying time-sensitive neurological and medical pathologies while using all available resources as purposefully as possible. Conclusions Our SOP may provide an appropriate tool for efficient management of patients with non- traumatic coma. Our results justify the assignment of the initial diagnostic workup to neurologists and internal specialists in collaboration with anaesthesiologists

Renal recovery following orthotopic liver transplant after prolonged kidney injury: Perspectives on diagnosing hepatorenal syndrome and determining which patients should undergo simultaneous liver kidney transplantation

We present a case of an individual with cirrhosis and renal failure. This case is notable because the patient was found to have hepatorenal syndrome (HRS) superimposed on Immunoglobulin A (IgA) nephropathy. After 8 months of dialysis, the patient had significant renal recovery following orthotopic liver transplant (OLT). Cases such as this are not likely to be rare, as case series have shown that IgA deposits are a common occurrence in patients with cirrhosis, including those who have HRS. While current diagnostic criteria for HRS emphasize the importance of excluding glomerular lesions, we argue that this approach should be reconsidered. More specifically, we feel that the diagnostic approach to HRS should be more inclusive of cases in which patients have simultaneous HRS and glomerular injury. In addition, our case highlights the challenges in determining which patients will benefit most from simultaneous liver–kidney transplants over OLTs alone

Crossover from adiabatic to sudden interaction quenches in the Hubbard model: Prethermalization and nonequilibrium dynamics

The recent experimental implementation of condensed matter models in optical lattices has motivated research on their nonequilibrium behavior. Predictions on the dynamics of superconductors following a sudden quench of the pairing interaction have been made based on the effective BCS Hamiltonian; however, their experimental verification requires the preparation of a suitable excited state of the Hubbard model along a twofold constraint: (i) a sufficiently nonadiabatic ramping scheme is essential to excite the nonequilibrium dynamics, and (ii) overheating beyond the critical temperature of superconductivity must be avoided. For commonly discussed interaction ramps there is no clear separation of the corresponding energy scales. Here we show that the matching of both conditions is simplified by the intrinsic relaxation behavior of ultracold fermionic systems: For the particular example of a linear ramp we examine the transient regime of prethermalization [M. Moeckel and S. Kehrein, Phys. Rev. Lett. 100, 175702 (2008)] under the crossover from sudden to adiabatic switching using Keldysh perturbation theory. A real-time analysis of the momentum distribution exhibits a temporal separation of an early energy relaxation and its later thermalization by scattering events. For long but finite ramping times this separation can be large. In the prethermalization regime the momentum distribution resembles a zero temperature Fermi liquid as the energy inserted by the ramp remains located in high energy modes. Thus ultracold fermions prove robust to heating which simplifies the observation of nonequilibrium BCS dynamics in optical lattices.Comment: 27 pages, 8 figures Second version with small modifications in section

Real-time evolution for weak interaction quenches in quantum systems

Motivated by recent experiments in ultracold atomic gases that explore the nonequilibrium dynamics of interacting quantum many-body systems, we investigate the nonequilibrium properties of a Fermi liquid. We apply an interaction quench within the Fermi liquid phase of the Hubbard model by switching on a weak interaction suddenly; then we follow the real-time dynamics of the momentum distribution by a systematic expansion in the interaction strength based on the flow equation method. In this paper we derive our main results, namely the applicability of a quasiparticle description, the observation of a new type of quasi-stationary nonequilibrium Fermi liquid like state and a delayed thermalization of the momentum distribution. We explain the physical origin of the delayed relaxation as a consequence of phase space constraints in fermionic many-body systems. This brings about a close relation to similar behavior of one-particle systems which we illustrate by a discussion of the squeezed oscillator; we generalize to an extended class of systems with discrete energy spectra and point out the generic character of the nonequilibrium Fermi liquid results for weak interaction quenches. Both for discrete and continuous systems we observe that particular nonequilibrium expectation values are twice as large as their corresponding analogues in equilibrium. For a Fermi liquid, this shows up as an increased correlation-induced reduction of the quasiparticle residue in nonequilibrium.Comment: 54 page

Dynamical evolution of star-forming regions

We model the dynamical evolution of star-forming regions with a wide range of initial properties. We follow the evolution of the regions’ substructure using the Q-parameter, we search for dynamical mass segregation using the !MSR technique, and we also quantify the evolution of local density around stars as a function of mass using the "LDR method. The amount of dynamical mass segregation measured by !MSR is generally only significant for subvirial and virialized, substructured regions – which usually evolve to form bound clusters. The "LDR method shows that massive stars attain higher local densities than the median value in all regions, even those that are supervirial and evolve to form (unbound) associations. We also introduce the Q − "LDR plot, which describes the evolution of spatial structure as a function of mass-weighted local density in a star-forming region. Initially dense (>1000 stars pc−2), bound regions always have Q > 1, "LDR > 2 after 5 Myr, whereas dense unbound regions always have Q 2 after 5 Myr. Less dense regions (<100 stars pc−2) do not usually exhibit "LDR > 2 values, and if relatively high local density around massive stars arises purely from dynamics, then the Q − "LDR plot can be used to estimate the initial density of a star-forming region

Dynamical population synthesis: Constructing the stellar single and binary contents of galactic field populations

[abridged] The galactic field's late-type stellar single and binary population is calculated on the supposition that all stars form as binaries in embedded star clusters. A recently developed tool (Marks, Kroupa & Oh) is used to evolve the binary star distributions in star clusters for a few Myr so that a particular mixture of single and binary stars is achieved. On cluster dissolution the population enters the galactic field with these characteristics. The different contributions of single stars and binaries from individual star clusters which are selected from a power-law embedded star cluster mass function are then added up. This gives rise to integrated galactic field binary distribution functions (IGBDFs) resembling a galactic field's stellar content (Dynamical Population Synthesis). It is found that the binary proportion in the galactic field of a galaxy is larger the lower the minimum cluster mass, the lower the star formation rate, the steeper the embedded star cluster mass function and the larger the typical size of forming star clusters in the considered galaxy. In particular, period-, mass-ratio- and eccentricity IGBDFs for the Milky Way are modelled. The afore mentioned theoretical IGBDFs agree with independently observed distributions. Of all late-type binaries, 50% stem from M<300M_sun clusters, while 50% of all single stars were born in M>10^4M_sun clusters. Comparison of the G-dwarf and M-dwarf binary population indicates that the stars formed in mass-segregated clusters. In particular it is pointed out that although in the present model all M-dwarfs are born in binary systems, in the Milky Way's Galactic field the majority ends up being single stars. This work predicts that today's binary frequency in elliptical galaxies is lower than in spiral and in dwarf-galaxies. The period and mass-ratio distributions in these galaxies are explicitly predicted.Comment: 14 pages, 9 figures, accepted for publication in MNRA