Pedestrian level of interaction on platform conflict areas by real-scale laboratory experiments

The objective of this work was to develop a new method to measure the interaction of passengers boarding and alighting at metro stations. This method included the Level of Interaction (LOI) as more precise indicator compared to the Level of Service (LOS). The method consisted of building a mock-up of a metro car and a series of simulation experiments in University College London’s Pedestrian Accessibility Movement Environmental Laboratory (PAMELA) based on observation at two London Underground station. This mock-up included Platform Edge Doors (PEDs) and a new space defined as Platform Conflict Area in front of the train doors in which the density of passengers was high. Results of the laboratory experiments were expressed according to the types of queues, formation of lanes, density by layer, and distance between passengers, in which the interaction followed a Logarithmic Distribution and no statistical differences were found with PEDs. These results are helpful for traffic engineers and policy makers to measure the interaction and use the LOI as a new indicator for the design of spaces in metro systems

Estimation of the passenger space in the boarding and alighting at metro stations

Platform edge doors (PEDs) have been used in various metro stations to improve safety and ventilation conditions, however limited research has been done to estimate the passenger space (PS) in the boarding and alighting process when PEDs are installed. The aim of this study was to estimate the space needed for boarding and alighting at metro stations. The method was based on a mock-up carriage and the relevant portion of the platform at University College London´s Pedestrian Accessibility Movement Environmental Laboratory (PAMELA), in which different load scenarios of boarding and alighting were conducted. The scenarios were based in a preliminary analysis observed at Westminster Station, in which PEDs are installed. To obtain the position of each passenger on the platform a tracking tool was used. The hypothesis of this research was that PS for alighting passengers can be represented as an asymmetrical ellipse, in which the longitudinal and lateral radii changed according to the negotiation with other passengers alighting or waiting on the platform to board the train. Therefore, there is a relationship between PS and the level of interaction, which suggests that passengers adjust their PS to avoid collision. This research can be used by traffic engineers to estimate PS of passengers boarding and alighting when PEDs are used. This in turn can help in designing the platform train interface (PTI) and platforms at transport infrastructures

Temperature-driven transition from the Wigner Crystal to the Bond-Charge-Density Wave in the Quasi-One-Dimensional Quarter-Filled band

It is known that within the interacting electron model Hamiltonian for the one-dimensional 1/4-filled band, the singlet ground state is a Wigner crystal only if the nearest neighbor electron-electron repulsion is larger than a critical value. We show that this critical nearest neighbor Coulomb interaction is different for each spin subspace, with the critical value decreasing with increasing spin. As a consequence, with the lowering of temperature, there can occur a transition from a Wigner crystal charge-ordered state to a spin-Peierls state that is a Bond-Charge-Density Wave with charge occupancies different from the Wigner crystal. This transition is possible because spin excitations from the spin-Peierls state in the 1/4-filled band are necessarily accompanied by changes in site charge densities. We apply our theory to the 1/4-filled band quasi-one-dimensional organic charge-transfer solids in general and to 2:1 tetramethyltetrathiafulvalene (TMTTF) and tetramethyltetraselenafulvalene (TMTSF) cationic salts in particular. We believe that many recent experiments strongly indicate the Wigner crystal to Bond-Charge-Density Wave transition in several members of the TMTTF family. We explain the occurrence of two different antiferromagnetic phases but a single spin-Peierls state in the generic phase diagram for the 2:1 cationic solids. The antiferromagnetic phases can have either the Wigner crystal or the Bond-Charge-Spin-Density Wave charge occupancies. The spin-Peierls state is always a Bond-Charge-Density Wave.Comment: 12 pages, 8 EPS figures. Longer version of previous manuscript. Contains new numerical data as well as greatly expanded discussio

Cluster dynamical mean-field study of the Hubbard model on a 3D frustrated hyperkagome lattice

We study the Hubbard model on a geometrically-frustrated hyperkagome lattice by a cluster extension of the dynamical mean field theory. We calculate the temperature ($T$) dependences of the specific heat ($C$) and the spin-lattice relaxation time ($T_1$) in correlated metallic region. $C/T$ shows a peak at $T=T_{p1}$ and rapidly decreases as $T->0$. On the other hand, $1/T_1T$ has a peak at a higher temperature $T_{p2}$ than $T_{p1}$, and largely decreases below $T_{p2}$, followed by the Korringa law $1/T_1 propto T$ as $T->0$. Both peak temperatures are suppressed and the peaks become sharper as electron correlation is increased. These behaviors originate from strong renormalization of the energy scales in the peculiar electronic structure in this frustrated system; a pseudo-gap like feature, the van-Hove singularity, and the flat band. The results are discussed in comparison with the experimental data in the hyperkagome material, Na$_4$Ir$_3$O$_8$.Comment: 4 pages, 4 figures, Conference proceedings for Highly Frustrated Magnetism 200

ECT seizure duration: Database information

Aim: In this naturalistic study the aim was to examine the impact on seizure duration of stimulus intensity, previous treatments (during the first course of ECT), age, gender, and electrode placement. Method: The database of the ECT Service of the Royal Hobart Hospital was examined for the 15 years ending in 2010. First courses of ECT were identified in which the stimulus intensity was not altered and at least 5 treatments were provided. Seizure duration was determined by cessation of clonic movements. Result: 383 patients (164 males) met selection criteria. A multiple regression analysis revealed that previous treatments, age, gender, and electrode placement had non-significant regression coefficient on the seizure length. The stimulus intensity, however, showed significant regression coefficient (-.267, p <.001), indicating that higher stimulus intensity induced shorter seizure duration. Conclusion: It was suggested that electrode placement and the number of treatments had negligible influence on seizure duration, while high stimulus intensity reduced seizure duration. If fixed high dose ECT is being provided, and there is concern due to the brevity of seizures, rather than taking steps to increase the output of the machine, a modest reduction of dose (perhaps to < 428.4 mC, or < 85% of machine output) may increase seizure duration (German J Psychiatry 2011; 14: 35–39)

Compensation of Effective Field in the Field-Induced Superconductor k-(BETS)2FeBr4 Observed by 77Se NMR

We report results of 77Se NMR frequency shift in the normal state of the organic charge-transfer-salt k-(BETS)2FeBr4 which shows magnetic field-induced superconductivity (FISC). From a simple mean field analysis, we determined the field and the temperature dependences of the magnetization m_{pi} of the \pi conduction electrons on BETS molecules. We found that the Fe spins are antiferromagnetically coupled to the pi electrons and determined the exchange field to be J = -2.3T/mu_B. The exchange field from the fully saturated Fe moments (5 mu_B) is compensated by an external field of 12T. This is close to the central field of the FISC phase, consistent with the Jaccarino-Peter local field-compensation mechanism for FISC (Phys. Rev. Lett. 9, 290 (1962))

A New Framework to Evaluate Passenger Interactions at Platform Train Interfaces

Platform train interfaces (PTIs) are spaces with high interactions between passengers boarding and alighting. A simple framework is proposed to help designers and planners to identify and benchmark the degree of interaction when crowd management measures are used such as platform edge doors (PEDs). Firstly, a conceptual model is created to represent the interaction problems, followed by the definition of variables. Then, the degree of interaction is defined based on the density and perception of risk. Finally, the results are presented in a matrix that groups the variables according to the area where the interaction happens, and to the type of users that are affected. As a case study, the framework is applied in this paper to two existing stations (with and without PEDs). The results show that the new framework is able to describe well the phenomena of high interactions and can be used to evaluate suitable crowd management measures in railway infrastructure and to communicate interaction problems in a simple and effective way

Boarding and alighting matrix on behaviour and interaction at the platform train interface

The platform train interface (PTI) is a space with high interactions between passengers boarding and alighting. The increasing need for faster and safer boarding/alighting led the Rail Safety Standards Board to publish the Platform Train Interface Strategy (2015). Because of the complex and multi-dimensional nature of these interactions, a simple framework is required to help designers and planners identify and benchmark the degree of interaction. This paper aims to create such a framework. This new framework consists of four steps. Firstly, a model is created to represent the interaction problems at the PTI. This model discretises the PTI into a square grid and divides the platform into concentric layers around the doors. Secondly, the model variables are identified and classified into physical, spatial and operational. Thirdly, the degree of interaction between passengers is defined as high, medium or low based on the density and perception of risk, and each of the variables is assigned one degree of interaction. Finally, the results are presented in a matrix that groups the variables according to the area where the interaction happens (vehicle, PTI, or platform) and to the type of users that are affected by this interaction (boarders only, alighters only, or both). As case study, this paper applies the framework to two existing stations. The results show that the new framework is able to describe well the phenomena of high interactions. In the case study, the presence of door position indications on the platform, the density, the location of passengers and the formation of lanes were the most relevant variables in the matrix. This paper further shows how this framework can be used to suggest or evaluate suitable crowd management measures in railway infrastructure and to summarise and communicate interaction problems in a simple and effective way