Properties of pedestrians walking in line: Stepping behavior

In human crowds, interactions among individuals give rise to a variety of self-organized collective motions that help the group to effectively solve the problem of coordination. However, it is still not known exactly how humans adjust their behavior locally, nor what are the direct consequences on the emergent organization. One of the underlying mechanisms of adjusting individual motions is the stepping dynamics. In this paper, we present first quantitative analysis on the stepping behavior in a one-dimensional pedestrian flow studied under controlled laboratory conditions. We find that the step length is proportional to the velocity of the pedestrian, and is directly related to the space available in front of him, while the variations of the step duration are much smaller. This is in contrast with locomotion studies performed on isolated pedestrians and shows that the local density has a direct influence on the stepping characteristics. Furthermore, we study the phenomena of synchronization -walking in lockstep- and show its dependence on flow densities. We show that the synchronization of steps is particularly important at high densities, which has direct impact on the studies of optimizing pedestrians flow in congested situations. However, small synchronization and antisynchronization effects are found also at very low densities, for which no steric constraints exist between successive pedestrians, showing the natural tendency to synchronize according to perceived visual signals.Comment: 8 pages, 5 figure

Properties of pedestrians walking in line - Fundamental diagrams

We present experimental results obtained for a one-dimensional flow using high precision motion capture. The full pedestrians' trajectories are obtained. In this paper, we focus on the fundamental diagram, and on the relation between the instantaneous velocity and spatial headway (distance to the predecessor). While the latter was found to be linear in previous experiments, we show that it is rather a piecewise linear behavior which is found if larger density ranges are covered. Indeed, our data clearly exhibits three distinct regimes in the behavior of pedestrians that follow each other. The transitions between these regimes occur at spatial headways of about 1.1 and 3 m, respectively. This finding could be useful for future modeling.Comment: 9 figures, 3 table

Generalized Centrifugal Force Model for Pedestrian Dynamics

A spatially continuous force-based model for simulating pedestrian dynamics is introduced which includes an elliptical volume exclusion of pedestrians. We discuss the phenomena of oscillations and overlapping which occur for certain choices of the forces. The main intention of this work is the quantitative description of pedestrian movement in several geometries. Measurements of the fundamental diagram in narrow and wide corridors are performed. The results of the proposed model show good agreement with empirical data obtained in controlled experiments.Comment: 10 pages, 14 figures, accepted for publication as a Regular Article in Physical Review E. This version contains minor change

Intraventricular Sialidase Administration Enhances GM1 Ganglioside Expression and Is Partially Neuroprotective in a Mouse Model of Parkinson\u27s Disease.

BACKGROUND: Preclinical and clinical studies have previously shown that systemic administration of GM1 ganglioside has neuroprotective and neurorestorative properties in Parkinson\u27s disease (PD) models and in PD patients. However, the clinical development of GM1 for PD has been hampered by its animal origin (GM1 used in previous studies was extracted from bovine brains), limited bioavailability, and limited blood brain barrier penetrance following systemic administration. OBJECTIVE: To assess an alternative therapeutic approach to systemic administration of brain-derived GM1 to enhance GM1 levels in the brain via enzymatic conversion of polysialogangliosides into GM1 and to assess the neuroprotective potential of this approach. METHODS: We used sialidase from Vibrio cholerae (VCS) to convert GD1a, GD1b and GT1b gangliosides to GM1. VCS was infused by osmotic minipump into the dorsal third ventricle in mice over a 4-week period. After the first week of infusion, animals received MPTP injections (20 mg/kg, s.c., twice daily, 4 hours apart, for 5 consecutive days) and were euthanized 2 weeks after the last injection. RESULTS: VCS infusion resulted in the expected change in ganglioside expression with a significant increase in GM1 levels. VCS-treated animals showed significant sparing of striatal dopamine (DA) levels and substantia nigra DA neurons following MPTP administration, with the extent of sparing of DA neurons similar to that achieved with systemic GM1 administration. CONCLUSION: The results suggest that enzymatic conversion of polysialogangliosides to GM1 may be a viable treatment strategy for increasing GM1 levels in the brain and exerting a neuroprotective effect on the damaged nigrostriatal DA system

Mechanistic drivers of mycorrhizal type effects on soil carbon and nitrogen cycling across scales

A large portion of terrestrial carbon (C) and nitrogen (N) are stored in soil organic matter (SOM) yet the factors driving the balance between C and N storage versus loss from SOM remain unclear. Tree-mycorrhizal association has emerged as a promising predictor of SOM dynamics with ECM stands characterized by slow C and N cycling and AM stands characterized by rapid C and N cycling. This dissertation investigates the mechanisms driving formation of distinct mycorrhizal nutrient syndromes at the neighborhood, stand and watershed scales. First, I found that ECM effects on SOM dynamics and N cycling can differ in magnitude and direction between watersheds that differ in soil pH and fertility, demonstrating the potential for intrinsic soil properties to mediate the effects of ECM trees and associated fungi on SOM formation and persistence in the tropics. Second, I found that underlying soil acid-base chemistry can shape fungal communities that lead to variation in ECM effects on SOM accumulation and N cycling. Third, I found that litter chemical quality and environmental conditions mediate the manifestation of slower decomposition in ECM stands such that leaf litter decomposition rates cannot be predicted directly from litter mycorrhizal type or stand mycorrhizal type. Finally, I show that gross N mineralization rates can be greater in ECM relative to AM stands despite slow nitrification and minimal N losses, demonstrating that suppressed mineralization of low quality ECM leaf litter does not directly drive closed N cycling in ECM stands. This work revealed the central role of environmental and geologic context in determining the mechanisms driving ectomycorrhizal (ECM) effects at spatial scales from individual trees to forest stands to watersheds. I conclude that the mechanisms driving mycorrhizal effects can vary across ecosystems, informing efforts to predict mycorrhizal effects at the global scale

Inference of Soil Hydrologic Parameters from Electronic Soil Moisture Records

Soil moisture is an important control on hydrologic function, as it governs vertical fluxes from and to the atmosphere, groundwater recharge, and lateral fluxes through the soil. Historically, the traditional model parameters of saturation, field capacity, and permanent wilting point have been determined by laboratory methods. This approach is challenged by issues of scale, boundary conditions, and soil disturbance. We develop and compare four methods to determine values of field saturation, field capacity, plant extraction limit (PEL), and initiation of plant water stress from long term in-situ monitoring records of TDR-measured volumetric water content (Θ). The monitoring sites represent a range of soil textures, soil depths, effective precipitation and plant cover types in a semi-arid climate. The Θ records exhibit attractors (high frequency values) that correspond to field capacity and the PEL at both annual and longer time scales, but the field saturation values vary by year depending on seasonal wetness in the semi-arid setting. The analysis for five sites in two watersheds is supported by comparison to values determined by a common pedotransfer function and measured soil characteristic curves. Frozen soil is identified as a complicating factor for the analysis and users are cautioned to filter data by temperature, especially for near surface soils

Assessing Biodegradability of Chemical Compounds from Microbial Community Growth Using Flow Cytometry.

Compound biodegradability tests with natural microbial communities form an important keystone in the ecological assessment of chemicals. However, biodegradability tests are frequently limited by a singular focus either on the chemical and potential transformation products or on the individual microbial species degrading the compound. Here, we investigated a methodology to simultaneously analyze community compositional changes and biomass growth on dosed test compound from flow cytometry (FCM) data coupled to machine-learned cell type recognition. We quantified the growth of freshwater microbial communities on a range of carbon dosages of three readily biodegradable reference compounds, phenol, 1-octanol, and benzoate, in comparison to three fragrances, methyl jasmonate, myrcene, and musk xylene (as a nonbiodegradable control). Compound mass balances with between 0.1 to 10 mg C · liter <sup>-1</sup> phenol or 1-octanol, inferred from cell numbers, parent compound analysis, and CO <sub>2</sub> evolution, as well as use of <sup>14</sup> C-labeled compounds, showed between 6 and 25% mg C · mg C <sup>-1</sup> substrate incorporation into biomass within 2 to 4 days and 25 to 45% released as CO <sub>2</sub> In contrast, similar dosage of methyl jasmonate and myrcene supported slower (4 to 10 days) and less (2.6 to 6.6% mg C · mg C <sup>-1</sup> with 4.9 to 22% CO <sub>2</sub> ) community growth. Community compositions inferred from machine-learned cell type recognition and 16S rRNA amplicon sequencing showed substrate- and concentration-dependent changes, with visible enrichment of microbial subgroups already at 0.1 mg C · liter <sup>-1</sup> phenol and 1-octanol. In general, community compositions were similar at the start and after the stationary phase of the microbial growth, except at the highest used substrate concentrations of 100 to 1,000 mg C · liter <sup>-1</sup> Flow cytometry cell counting coupled to deconvolution of communities into subgroups is thus suitable to infer biodegradability of organic chemicals, permitting biomass balances and near-real-time assessment of relevant subgroup changes.IMPORTANCE The manifold effects of potentially toxic compounds on microbial communities are often difficult to discern. Some compounds may be transformed or completely degraded by few or multiple strains in the community, whereas others may present inhibitory effects. In this study, we benchmark a new method based on machine-learned microbial cell recognition to rapidly follow dynamic changes in aquatic communities. We further determine productive biodegradation upon dosing of a number of well-known readily biodegradable tester compounds at a variety of concentrations. Microbial community growth was quantified using flow cytometry, and the multiple cell parameters measured were used in parallel to deconvolute the community on the basis of similarity to previously standardized cell types. Biodegradation was further confirmed by chemical analysis, showing how distinct changes in specific populations correlate to degradation. The method holds great promise for near-real-time community composition changes and deduction of compound biodegradation in natural microbial communities

Forging a performance practice for Debussy’s Douze Études: a historical and analytical approach

This document integrates discussions of historical and analytical findings to support a performance practice surrounding Debussy’s Douze Études (1915). Historical observations are used to build comparative relationships between the compositional techniques and piano techniques used in the Études and those established by The French Clavecinistes; Debussy’s teachers, mentors and peers at The Paris Conservatory; Frédéric Chopin; and Robert Schumann. These relationships are used to highlight stylistic nuances that are paramount to the interpretation of Debussy’s music. While the Études provide the lens through which Debussy’s piano style is examined, this document is organized by topic, drawing upon individual études to illustrate various elements of style. These include: French Baroque unmeasured préludes, keyboard technique of the French Baroque, keyboard technique of the Paris Conservatory, keyboard technique of Chopin, Chopin’s rubato, Chopin’s rhythmic vernacular, Schumann’s explorations in sonority, Schumann’s use of repetition, Schumann’s use of quotation, and finally, Schumann’s use of contrasting characters

Pre- and postbariatric subtypes and their predictive value for health-related outcomes measured three years after surgery

Background: Although bariatric surgery is the most effective treatment for severe obesity, a subgroup of patients shows insufficient postbariatric outcomes. Differences may at least in part result from heterogeneous patient profiles regarding reactive and regulative temperament, emotion dysregulation, and disinhibited eating. This study aims to subtype patients based on these aspects before and two years after bariatric surgery and tests the predictive value of identified subtypes for health-related outcomes three years after surgery