Macro and Micro Dynamics of City Size Distributions: The Case of Israel

We study the distribution of sizes in the Israeli system of cities, using a rank-size representation of population distributions from 1950 to 2005. Based on a multiplicative model of proportionate growth, we develop a quantitative comparison relating the change in the rank-size curves to the change in the real data of Israeli cities during this period. At the level of macro dynamics, there is good agreement between the model and the real data. At the micro level, however, the model is less successful as the mean variation of the cities’ rank during the period studied is much larger in the model than in the real data. To illustrate this difference, we use the rankclock representation

Towards active microfluidics: Interface turbulence in thin liquid films with floating molecular machines

Thin liquid films with floating active protein machines are considered. Cyclic mechanical motions within the machines, representing microscopic swimmers, lead to molecular propulsion forces applied to the air-liquid interface. We show that, when the rate of energy supply to the machines exceeds a threshold, the flat interface becomes linearly unstable. As the result of this instability, the regime of interface turbulence, characterized by irregular traveling waves and propagating machine clusters, is established. Numerical investigations of this nonlinear regime are performed. Conditions for the experimental observation of the instability are discussed.Comment: 9 pages, 8 figures, RevTeX, submitted to Physical Review

Molecular Discreteness in Reaction-Diffusion Systems Yields Steady States Not Seen in the Continuum Limit

We investigate the effects of spatial discreteness of molecules in reaction-diffusion systems. It is found that discreteness within the so called Kuramoto length can lead to a localization of molecules, resulting in novel steady states that do not exist in the continuous case. These novel states are analyzed theoretically as the fixed points of accelerated localized reactions, an approach that was verified to be in good agreement with stochastic particle simulations. The relevance of this discreteness-induced state to biological intracellular processes is discussed.Comment: 5 pages, 3 figures, revtex

Instabilities of a liquid layer locally heated on its free surface

International audienceWe report experimental results concerning patterns in a model experiment built to studybuoyant-thermocapillary-driven flows. The fluid is situated in a cooled cylindrical container andlocally heated on its free surface. The resulting temperature gradient induces a basic flow whichdraws the surface fluid from the hot center toward the cold boundary. When the gradient is increasedand depending on the height of liquid, the basic flow destabilizes into different stationary patterns.Above a second threshold, the patterns become time-dependent. These different instabilities arecharacterized and compared to recent theoretical results

Singular Laplacian Growth

The general equations of motion for two dimensional Laplacian growth are derived using the conformal mapping method. In the singular case, all singularities of the conformal map are on the unit circle, and the map is a degenerate Schwarz-Christoffel map. The equations of motion describe the motions of these singularities. Despite the typical fractal-like outcomes of Laplacian growth processes, the equations of motion are shown to be not particularly sensitive to initial conditions. It is argued that the sensitivity of this system derives from a novel cause, the non-uniqueness of solutions to the differential system. By a mechanism of singularity creation, every solution can become more complex, even in the absence of noise, without violating the growth law. These processes are permitted, but are not required, meaning the equation of motion does not determine the motion, even in the small.Comment: 8 pages, Latex, 4 figures, Submitted to Phys. Rev.

A feasibility study highlighting challenges in evaluating a structured, psychological treatment for self-harm in adult psychiatric inpatient settings

BACKGROUND: Despite being the most common reason for admission to psychiatric inpatient services, no evidence-based treatment currently exists for self-harm in this setting. Dialectical Behavioural Therapy (DBT) trials have found promising results in treating self-harm in outpatient settings; however findings for inpatient settings are still limited. METHOD: A single-arm feasibility trial was conducted examining a DBT-informed 'Coping with Crisis' (CwC) group protocol, which focused on self-harm and crisis management strategies. Twenty-four participants were recruited from an inpatient ward in a National Health Service (NHS) Trust in the UK. The Inventory of Statements about Self-Injury and Distress Tolerance Scale were administered at baseline and post-therapy. Data was collected on the rates of recruitment, retention, session attendance, outcome measure completion, adverse events and participant feedback, in order to inform the design of a main study. RESULTS: Findings indicated that it was feasible to run the CWC group and research study on an inpatient ward. However, there were several challenges in recruiting to target (80% achieved) and retaining participants (38% of consented participants completed). A number of implementation issues were identified and recommendations have been made to inform future group and study designs

Successful Cessation Programs that Reduce Comorbidity May Explain Surprisingly Low Smoking Rates Among Hospitalized COVID-19 Patients

A recent, non-peer-reviewed meta-analysis suggests that smoking may reduce the risk of hospitalization with COVID-19 because the prevalence of smoking among hospitalized COVID-19 is less than that of the general population. However, there are alternative explanations for this phenomena based on (1) the failure to report, or accurately record, smoking history during emergency hospital admissions and (2) a pre-disposition to avoid smoking among COVID-19 patients with tobacco-related comorbidities (a type of “reverse” causation). For example, urine testing of hospitalized patients in Australia for cotinine showed that smokers were under-counted by 37% because incoming patients failed to inform staff about their smoking behavior. Face-to-face interviews can introduce bias into the responses to attitudinal and behavioral questions not present in the self-completion interviews typically used to measure smoking prevalence in the general population. Subjects in face-to-face interviews may be unwilling to admit socially undesirable behavior and attitudes under direct questioning. Reverse causation may also contribute to the difference between smoking prevalence in the COVID-19 and general population. Patients hospitalized with COVID-19 may be simply less prone to use tobacco than the general population. A potentially robust “reverse causation” hypothesis for reduced prevalence of smokers in the COVID-19 population is the enrichment of patients in that population with serious comorbidities that motivates them to quit smoking. We judge that this “smoking cessation” mechanism may account for a significant fraction of the reduced prevalence of smokers in the COVID-19 population. Testing this hypothesis will require a focused research program

Enabling Communities in the Use and Application of NASA's Earth Science Data and Information Products: Interactive Webinars that Work

The vast active archives of NASA's Earth science data reflect the agency's ongoing commitment to producing the highest quality data, services and tools intended for a myriad of science and application uses worldwide. These data span the whole of Earth science domains, and most have direct uses in societal applications. As many internet-based tools mature they enable NASA to increase the availability to and, most importantly, the uses of these disparate data types. This poster/paper highlights one particularly effective tool the NASA Earth Science Data and Information System (ESDIS) Project is utilizing to increase our user communities' understanding of these data, services and tools and their varied uses. Webinars, or video-based, on-line, interactive discussions and presentations have become a staple for exchanging information via the internet. The NASA ESDIS Project is using this platform to create a rich, highly-available, source of cutting-edge insights into the uses of Earth science data and applications. As evidence, we present a representative sample of the webinar offerings created by ESDIS beginning in 2013

Non-linear conformally invariant generalization of the Poisson equation to D>2 dimensions

I propound a non-linear generalization of the Poisson equation describing a "medium" in D dimensions with a "dielectric constant" proportional to the field strength to the power D-2. It is the only conformally invariant scalar theory that is second order, and in which the scalar $phi$ couples to the sources $\rho$ via a $\phi\rho$ contact term. The symmetry is used to generate solutions for the field for some non-trivial configurations (e.g. for two oppositely charged points). Systems comprising N point charges afford further application of the symmetry. For these I derive e.g. exact expressions for the following quantities: the general two-point-charge force; the energy function and the forces in any three-body configuration with zero total charge; the few-body force for some special configurations; the virial theorem for an arbitrary, bound, many-particle system relating the time-average kinetic energy to the particle charges. Possible connections with an underlying conformal quantum field theory are mentioned.Comment: Revtex, 16 pages. To be published in Phys. Rev.

Status of the HIE-ISOLDE project at CERN

The HIE-ISOLDE project represents a major upgrade of the ISOLDE nuclear facility with a mandate to significantly improve the quality and increase the intensity and energy of radioactive nuclear beams produced at CERN. The project will expand the experimental nuclear physics programme at ISOLDE by focusing on an upgrade of the existing Radioactive ion beam EXperiment (REX) linac with a 40 MV superconducting linac comprising thirty-two niobium-on-copper sputter-coated quarter-wave resonators housed in six cryomodules. The new linac will raise the energy of post-accelerated beams from 3 MeV/u to over 10 MeV/u. The upgrade will be staged to first deliver beam energies of 5.5 MeV/u using two high-$\beta$ cryomodules placed downstream of REX, before the energy variable section of the existing linac is replaced with two low-$\beta$ cryomodules and two additional high-$\beta$ cryomodules are installed to attain over 10 MeV/u with full energy variability above 0.45 MeV/u. An overview of the project including a status summary of the different R&D activities and the schedule will outlined.Comment: 7 pages, 12 figures, submitted to the Heavy Ion Accelerator Technology conference (HIAT) 2012, in Chicag