Dynamic density functional theory with inertia and background flow.

We present dynamic density functional theory (DDFT) incorporating general inhomogeneous, incompressible, time-dependent background flows and inertia, describing externally driven passive colloidal systems out of equilibrium. We start by considering the underlying nonequilibrium Langevin dynamics, including the effect of the local velocity of the surrounding liquid bath, to obtain the nonlinear, nonlocal partial differential equations governing the evolution of the (coarse-grained) density and velocity fields describing the dynamics of colloids. In addition, we show both with heuristic arguments, and by numerical solution, that our equations and solutions agree with existing DDFTs in the overdamped (high friction) limit. We provide numerical solutions that model the flow of hard spheres, in both unbounded and confined domains, and compare with previously derived DDFTs with and without the background flow.

Stability of nanoparticle laden aerosol liquid droplets.

We develop a model for the thermodynamics and evaporation dynamics of aerosol droplets of a liquid, such as water, surrounded by gas. When the temperature and the chemical potential (or equivalently the humidity) are such that the vapor phase is in the thermodynamic equilibrium state, then, of course, droplets of the pure liquid evaporate over a relatively short time. However, if the droplets also contain nanoparticles or any other non-volatile solute, then the droplets can become thermodynamically stable. We show that the equilibrium droplet size depends strongly on the amount and solubility of the nanoparticles within, i.e., on the nature of the particle interactions with the liquid and, of course, also on the vapor temperature and chemical potential. We develop a simple thermodynamic model for such droplets and compare predictions with results from a lattice density functional theory that takes as input the same particle interaction properties, finding very good agreement. We also use dynamical density functional theory to study the evaporation/condensation dynamics of liquid from/to droplets as they equilibrate with the vapor, thereby demonstrating droplet stability.

Proton Bunch Self-Modulation in Plasma with Density Gradient.

We study experimentally the effect of linear plasma density gradients on the self-modulation of a 400 GeV proton bunch. Results show that a positive or negative gradient increases or decreases the number of microbunches and the relative charge per microbunch observed after 10 m of plasma. The measured modulation frequency also increases or decreases. With the largest positive gradient we observe two frequencies in the modulation power spectrum. Results are consistent with changes in wakefields' phase velocity due to plasma density gradients adding to the slow wakefields' phase velocity during self-modulation growth predicted by linear theory.

Proton-driven plasma wakefield acceleration in AWAKE.

In this article, we briefly summarize the experiments performed during the first run of the Advanced Wakefield Experiment, AWAKE, at CERN (European Organization for Nuclear Research). The final goal of AWAKE Run 1 (2013-2018) was to demonstrate that 10-20 MeV electrons can be accelerated to GeV energies in a plasma wakefield driven by a highly relativistic self-modulated proton bunch. We describe the experiment, outline the measurement concept and present first results. Last, we outline our plans for the future. This article is part of the Theo Murphy meeting issue 'Directions in particle beam-driven plasma wakefield acceleration'.

First Search for Short-Baseline Neutrino Oscillations at HFIR with PROSPECT.

This Letter reports the first scientific results from the observation of antineutrinos emitted by fission products of ^{235}U at the High Flux Isotope Reactor. PROSPECT, the Precision Reactor Oscillation and Spectrum Experiment, consists of a segmented 4 ton ^{6}Li-doped liquid scintillator detector covering a baseline range of 7-9 m from the reactor and operating under less than 1 m water equivalent overburden. Data collected during 33 live days of reactor operation at a nominal power of 85 MW yield a detection of 25 461±283 (stat) inverse beta decays. Observation of reactor antineutrinos can be achieved in PROSPECT at 5σ statistical significance within 2 h of on-surface reactor-on data taking. A reactor model independent analysis of the inverse beta decay prompt energy spectrum as a function of baseline constrains significant portions of the previously allowed sterile neutrino oscillation parameter space at 95% confidence level and disfavors the best fit of the reactor antineutrino anomaly at 2.2σ confidence level.

Nonequilibrium molecular dynamics simulations of nanoconfined fluids at solid-liquid interfaces.

We investigate the hydrodynamic properties of a Lennard-Jones fluid confined to a nanochannel using molecular dynamics simulations. For channels of different widths and hydrophilic-hydrophobic surface wetting properties, profiles of the fluid density, stress, and viscosity across the channel are obtained and analysed. In particular, we propose a linear relationship between the density and viscosity in confined and strongly inhomogeneous nanofluidic flows. The range of validity of this relationship is explored in the context of coarse grained models such as dynamic density functional-theory.

An algorithm for filtering detector instabilities in search of novel non-exponential decay and in conventional half-life determinations.

Recent reports of Solar modulation of beta-decay have reignited interest in whether or not radioactive half-lives are constants. A numerical approach for filtering instrumental effects on residuals is developed, using correlations with atmospheric conditions recorded while counting 204Tl emissions with a Geiger-Müller counter. Half-life oscillations and detection efficiency oscillations can be separated provided their periods are substantially different. A partial uncertainty budget for the 204Tl half-life shows significant decreases to medium-frequency instabilities correlated with pressure and temperature, which suggests that further development may aid general improvements in half-life determinations.

Wave packet dynamics in the optimal superadiabatic approximation.

We explain the concept of superadiabatic representations and show how in the context of electronically non-adiabatic transitions they lead to an explicit formula that can be used to predict transitions at avoided crossings. Based on this formula, we present a simple method for computing wave packet dynamics across avoided crossings. Only knowledge of the adiabatic potential energy surfaces near the avoided crossing is required for the computation. In particular, this means that no diabatization procedure is necessary, the adiabatic electronic energies can be computed on the fly, and they only need to be computed to higher accuracy when an avoided crossing is detected. We test the quality of our method on the paradigmatic example of photo-dissociation of NaI, finding very good agreement with results of exact wave packet calculations.

Dynamical density functional theory with hydrodynamic interactions in confined geometries.

We study the dynamics of colloidal fluids in both unconfined geometries and when confined by a hard wall. Under minimal assumptions, we derive a dynamical density functional theory (DDFT) which includes hydrodynamic interactions (HI; bath-mediated forces). By using an efficient numerical scheme based on pseudospectral methods for integro-differential equations, we demonstrate its excellent agreement with the full underlying Langevin equations for systems of hard disks in partial confinement. We further use the derived DDFT formalism to elucidate the crucial effects of HI in confined systems.

Multi-species dynamical density functional theory.

We study the dynamics of a multi-species colloidal fluid in the full position-momentum phase space. We include both inertia and hydrodynamic interactions, which strongly influence the non-equilibrium properties of the system. Under minimal assumptions, we derive a dynamical density functional theory (DDFT), and, using an efficient numerical scheme based on spectral methods for integro-differential equations, demonstrate its excellent agreement with the full underlying Langevin equations. We utilise the DDFT formalism to elucidate the crucial effects of hydrodynamic interactions in multi-species systems.

Unification of dynamic density functional theory for colloidal fluids to include inertia and hydrodynamic interactions: derivation and numerical experiments.

Starting from the Kramers equation for the phase-space dynamics of the N-body probability distribution, we derive a dynamical density functional theory (DDFT) for colloidal fluids including the effects of inertia and hydrodynamic interactions (HI). We compare the resulting theory to extensive Langevin dynamics simulations for both hard rod systems and three-dimensional hard sphere systems with radially symmetric external potentials. As well as demonstrating the accuracy of the new DDFT, by comparing with previous DDFTs which neglect inertia, HI, or both, we also scrutinize the significance of including these effects. Close to local equilibrium we derive a continuum equation from the microscopic dynamics which is a generalized Navier-Stokes-like equation with additional non-local terms governing the effects of HI. For the overdamped limit we recover analogues of existing configuration-space DDFTs but with a novel diffusion tensor.

Termination of a contract to implement an enterprise electronic medical record system.

The development of integrated health care systems, the building of distributed computer networks throughout them, and the advent of easy-to-use electronic medical records for ambulatory practices combine to create a powerful argument for an enterprise electronic medical record. Potential customers need to learn from both successes and failures. Although the author could find in the literature only two reports of failures, a survey of family practice residencies revealed ten programs in which use of an electronic medical record had been discontinued. The author reports on a project that was terminated even though the technology was adequate to achieve the original project goals.

Spatial heterogeneity of soil water around single roots: use of CT-scanning to predict fungal growth in the rhizosphere.

Whole-body computed tomography X-ray scanning (X-ray CT) of wheat, cotton and radish growing in pots containing 350 g of a white sand: clay mixture produced images from which digital data of the volumetric water content were obtained. The volumetric water contents were spatially heterogeneous around the root and altered with the depth at which the image was taken. Data represent a 'snapshot in time' of the soil around single roots in a living soil-plant system. The volumetric water contents of soil around seedlings were assessed for the growth of two soil-borne fungi, Gaeumannomyces graminis var. tritici and Rhizoctonia solani. The heterogeneity of water content was biologically significant: water contents around the roots of wheat, radish and cotton were of a great enough range to suggest the existence of heterogeneous sites in the rhizosphere which might favour or restrict fungal growth. In soil surrounding wheat roots, the most favourable regions for the growth of G. graminis were nearest the root, suggesting that the inner rhizosphere might be more amenable to the growth of this pathogenic fungus than the outer region of the rhizosphere, and the bulk soil. The technique of X-ray CT enables spatial examination of the response of soil water to environmental treatments of the soil-root system, and the non-destructive observation of the effect of the spatial heterogeneity of volumetric water content upon fungal growth in the soil, over time and at a range of depths.

Use of Organic Acids To Improve the Chemical, Physical, and Microbial Attributes of Beef Strip Loins Stored at -1°C for 112 Days ‡.

Twenty-one beef strip loins (Institutional Meat Purchasers Specification #180) were cut into equal halves. One-half of each loin was sprayed with a mixture of 2% lactic acid and 2% (vol/vol) acetic acid and the corresponding half was used as a control. The strip loins were stored at -1°C for 0, 7, 14, 28, 56, 84, or 112 days and evaluated for chemical, physical, and microbial properties. The internal pH increased significantly (P < 0.05) beginning at day 56 for all products. Vacuum scores and visible purge scores showed that these qualities became less desirable over storage time. There were no significant differences (P > 0.05) for meat color, fat color, or odor over storage time. Acid-treated strip loins had significantly lower (P < 0.05) visible purge scores than control strip loins. Internal and external pH, vacuum, meat color, fat color, and odor were not affected by acid treatment. In a calculation of time-by-treatment interaction (P < 0.05), acid-sprayed strip loins had less percentage of purge than corresponding controls at 56 and 112 days of storage. Water-holding capacity decreased over 84 days of storage. Anaerobes, lactic acid-producing bacteria, and psychrotroph populations increased significantly (P < 0.05) over storage time but anaerobes and lactic acid-producing bacteria were reduced by acid treatment. Acid-sprayed strip loins had significantly lower aerobic (P < 0.05) and psychrotrophic (P < 0.1) populations than controls after 14 days. These data indicate that an acid spray immediately prior to packaging can reduce some species of bacteria without adversely affecting the physical properties of products stored for 112 days at -1°C.

Radionuclide evaluation of valvular regurgitation.

A non-invasive nuclear medicine technique for the assessment of aortic and mitral regurgitation may be of importance in the management of patients with valvular disease. Rigo et al (1979) introduced a method based on measuring the ratio of the left ventricular stroke volume to the right ventricular stroke volume from radionuclide equilibrium gated blood-pool images of the heart. In this paper we report our results using this technique. They indicate that caution should be exercised, and in particular that methods used to define the ventricular regions of interest must be carefully examined.

Prediction of late ischaemic complications after cerebral aneurysm surgery--use of a mobile microcomputer system for the measurement of pre-, intra- and postoperative cerebral blood flow.

Patients with defective autoregulation of cerebral blood flow are at much greater risk of developing late cerebral ischaemia after intracranial aneurysm surgery. This finding was based on data derived from the intraoperative measurement of the response of the cerebral circulation to hypotension, deliberately induced to assist dissection and clipping of the aneurysm. A preoperative test which gave the same information as the intraoperative measurements might be helpful in predicting the optimal timing of aneurysm surgery. However, the original intraoperative intravenous 133Xenon injection method was limited both by the need to analyse the data off-line and the restricted number of runs (up to 6). This paper describes the modifications used, based on the Apple II microprocessor, to obtain values of cerebral blood flow within 6 minutes of the injection of 133Xenon with up to 15-20 runs per patient.

Detection and interaction of elastic and flow-resistive respiratory loads in man.

1. The detection of added inspiratory airflow resistances was studied in normal individuals under two circumstances: first, while breathing unhindered, and secondly, while breathing against continuously applied ('basal') inspiratory elastic loads. The addition of basal elastic loads resulted in impaired detection of flow-resistive loads whether expressed as added flow resistance or as a proportion of the basal flow resistance. 2. When loads were plotted on a logarithmic scale, load-detection relationships were linear, permitting both threshold and slope of the detection response ('sensitivity') to be assessed. Impaired detection associated with basal elastic loads was shown to be due to a raised threshold without change in 'sensitivity'. 3. When the flow resistances submitted for detection were expressed as a proportion of the sum of the basal flow resistance and added elastance, the probability of detection was independent of the magnitude of the added elastance. 4. The interaction between basal elastic and added flow-resistive loads suggests that at the time of detection the basal elastance acts in a manner similar to that of an added flow resistance. 5. Added basal flow resistances had no significant effect on the detection of threshold elastic loads.