Polar features in the flagellar propulsion of E. coli bacteria

E. coli bacteria swim following a run and tumble pattern. In the run state all flagella join in a single helical bundle that propels the cell body along approximately straight paths. When one or more flagellar motors reverse direction the bundle unwinds and the cell randomizes its orientation. This basic picture represents an idealization of a much more complex dynamical problem. Although it has been shown that bundle formation can occur at either pole of the cell, it is still unclear whether this two run states correspond to asymmetric propulsion features. Using holographic microscopy we record the 3D motions of individual bacteria swimming in optical traps. We find that most cells possess two run states characterised by different propulsion forces, total torque and bundle conformations. We analyse the statistical properties of bundle reversal and compare the hydrodynamic features of forward and backward running states. Our method is naturally multi-particle and opens up the way towards controlled hydrodynamic studies of interacting swimming cells

Assessing the Frequency and Influences of Secondary Traumatic Stress Symptoms Among Crisis Intervention Workers

This study examined the differences in secondary traumatic stress symptomotology in crisis intervention workers by their field of work (job title), level of experience, level of participation in stress reducing activities, and perception of having received adequate training to meet the challenges of disaster and trauma work. The purpose of the study was to contribute to developing a better understanding of factors that influence crisis intervention workers\u27 experience of secondary traumatic stress. Analysis of variance (ANOVA) was used to study 206 crisis intervention workers drawn from four different crisis intervention fields (personal care/nurses\u27 aides, disaster relief workers, police officers, and professional counselors). Evidence of STS symptoms was determined by scores on the Compassion Fatigue (CF) subscale of the Compassion Satisfaction and Fatigue Test (CSF; Stamm and Figley, 1998). Demographic variables such as field of work, level of experience, participation in stress-reducing activities, and training were assessed on the Demographic/Trauma Work Questionnaire. No statistical significance was found to indicate a difference in the level of STS symptomotology in crisis intervention workers in relation to the variables studied. Because past research seems to support the idea that adequate self-care, greater experience, and adequate training reduce the level of STS symptoms in crisis intervention workers, the results were unexpected. Within the sample population, there existed substantial groups scoring at both ends of the spectrum (very low and very high risk for CF). This investigation was not able to determine what accounted for the difference between the high and low risk individuals. However, it was noted that a significantly larger portion of the personal care/nurses\u27 aides group scored in the very-high risk for CF range than did the other groups. It may have been possible to determine the reason for this with more in-depth querying of the individual respondents. Future research might consider a more comprehensive and specific questionnaire to gain better insights into the personal and professional life experiences of these individuals that may impact STS symptom development

Indoor radon survey in university buildings: a case study of Sapienza - University of Rome

The indoor radon concentration in underground workplaces pertaining to Sapienza – University of Rome have been monitored since the 90’s according to prescription of Italian Legislative Decree 230/95. In the last years, the recommendations contained in the Council Directive 2013/59/Euratom have shifted the focus to all indoor exposure situations by promoting actions to identify workplaces and dwellings with radon concentrations exceeding the reference level of 300 Bq/m3. In response to the upcoming transposition into national legislation, Sapienza has promoted the first Italian survey addressing workplaces in university buildings, regardless of the position with respect to the ground floor. The survey has interested more than three hundred workplaces, i.e. administration and professors’ offices, research and educational laboratories, conference rooms and classrooms, distributed in fifteen different buildings. Places monitored are strongly heterogeneous in terms of users’ habit, occupancy pattern and building characteristics. The influence of these parameters into seasonal variation have been addressed by organizing the survey in four quarters. The indoor radon concentration is measured by solid state nuclear track detectors, CR39. The aim of the paper is to present features, methods and intermediate results of the survey. The work, relying on the analysis of previous measurements interesting underground workplaces, focuses on methodology followed during all the preliminary and preparatory phases: active measurements by ionization chamber radon continuous monitor, radon progeny equilibrium factor estimations by radon daughters monitor, strategies for occupants’ awareness, positioning protocol and provisions to maximize representativity of results

Oligopoly Intermediation, Relative Rivalry, and the Mode of Competition

Policy design in oligopolistic settings depends critically on the mode of competition between firms. We develop a model of oligopoly intermediation that reveals the mode of competition to be an equilibrium outcome that depends on the relative degree of rivalry between firms in the upstream and downstream markets. We examine two forms of sequential pricing games: Purchasing to stock (PTS), in which firms select input prices prior to setting consumer prices; and purchasing to order (PTO), in which firms sell forward contracts to consumers prior to selecting input prices. The equilibrium outcomes of the model range between Bertrand and Cournot depending on the relative degree of rivarly between firms in the upstream and downstream markets. Prices are strategic complements and the equilibrium prices coincide with the Bertrand outcome when the markets are equally rivalrous, while prices are strategic substitutes when the degree of rivalry is sufficiently high in one market relative to the other. Cournot outcomes emerge under circumstances in which prices are strategically independent in either the upstream or downstream market. We derive testable implications for the mode of competition that depend only on primitive conditions of supply and demand functions

Oligopoly Intermediation, Relative Rivalry, and the Mode of Competition

Policy design in oligopolistic settings depends critically on the mode of competition between firms. We develop a model of oligopoly intermediation that reveals the mode of competition to be an equilibrium outcome that depends on the relative degree of rivalry between firms in the upstream and downstream markets. We examine two forms of sequential pricing games: Purchasing to stock (PTS), in which firms select input prices prior to setting consumer prices; and purchasing to order (PTO), in which firms sell forward contracts to consumers prior to selecting input prices. The equilibrium outcomes of the model range between Bertrand and Cournot depending on the relative degree of rivarly between firms in the upstream and downstream markets. Prices are strategic complements and the equilibrium prices coincide with the Bertrand outcome when the markets are equally rivalrous, while prices are strategic substitutes when the degree of rivalry is sufficiently high in one market relative to the other. Cournot outcomes emerge under circumstances in which prices are strategically independent in either the upstream or downstream market. We derive testable implications for the mode of competition that depend only on primitive conditions of supply and demand functions

Experimental evaluation of an advanced Space Shuttle main engine hot-gas manifold design concept

This study, using an extensively modified, full-scale space shuttle main engine (SSME) hot-gas manifold (HGM), established a detailed aerodynamic data base to support development of an advanced, three-dimensional, fluid-dynamic analysis computer model. In addition, the advanced SSME hot-gas manifold design used in this study demonstrated improved flow environment (uniformity) in the fuel side turbine exit and transfer duct exit regions. Major modifications were incorporated in the full-scale HGM flow test article model using two large transfer ducts on the fuel turbine side of the HGM in place of the three small transfer ducts in the present design. Other model features included an increases in the flow areas downstream of the 180-degree turn and in the fishbowl regions

An Experimental Study on the Influence of Soundscapes on People’s Behaviour in an Open Public Space

Several studies have investigated how environmental sounds and music can modulate people’s behaviours, particularly in marketing research. However, there are relatively few examples of research about such relationships with a focus on the management of urban public spaces. The current study investigated an open public space used mainly as a pedestrian crossing to analyse the relationship between the audio stimuli and peoples’ behaviours. An experiment relying on covert behavioural observation was performed. During the experiment, three different music stimuli and a control condition (i.e., no music) were reproduced in order to find out firstly whether music compared to no music could elicit an increase in the number of people stopping in the investigated area, and secondly whether music is associated with a longer duration of stay for those who stop. Results showed that the presence of music had no effect on the number of people stopping in the area, but it had a statistically significant effect on the duration of stay for those who stopped. The above findings support the idea that people felt more invited to stay in the area with music rather than with no music, and suggest that the acoustical manipulation of the existing sound environment could provide soundscape strategies capable of promoting social cohesion in public spaces

Statistical hadronization and hadronic microcanonical ensemble I

We present a full treatment of the microcanonical ensemble of the ideal hadron-resonance gas in a quantum-mechanical framework which is appropriate for the statistical model of hadronization. By using a suitable transition operator for hadronization we are able to recover the results of the statistical theory, particularly the expressions of the rates of different channels. Explicit formulae are obtained for the phase space volume or density of states of the ideal relativistic gas in quantum statistics which, for large volumes, turn to a cluster decomposition whose terms beyond the leading one account for Bose-Einstein and Fermi-Dirac correlations. The problem of the computation of the microcanonical ensemble and its comparison with the canonical one, which will be the main subject of a forthcoming paper, is addressed.Comment: 15 pages, LaTeX macros svjour.cls and svepj.clo needed, revised version to be published in Eur. Phys. J.