Conductivity in Jurkat cell suspension after ultrashort electric pulsing

Ultrashort electric pulses applied to similar cell lines such as Jurkat and HL-60 cells can produce markedly different results , which have been documented extensively over the last few years. We now report changes in electrical conductivity of Jurkat cells subjected to traditional electroporation pulses (50 ms pulse length) and ultrashort pulses (10 ns pulse length) using time domain dielectric spectroscopy (TDS). A single 10 ns, 150 kV/cm pulse did not noticeably alter suspension conductivity while a 50 ms, 2.12 kV/cm pulse with the same energy caused an appreciable conductivity rise. These results support the hypothesis that electroporation pulses primarily interact with the cell membrane and cause conductivity rises due to ion transport from the cell to the external media, while pulses with nanosecond duration primarily interact with the membranes of intracellular organelles. However, multiple ultrashort pulses have a cumulative effect on the plasma membrane, with five pulses causing a gradual rise in conductivity up to ten minutes post-pulsing

Canonical Transformations and Path Integral Measures

This paper is a generalization of previous work on the use of classical canonical transformations to evaluate Hamiltonian path integrals for quantum mechanical systems. Relevant aspects of the Hamiltonian path integral and its measure are discussed and used to show that the quantum mechanical version of the classical transformation does not leave the measure of the path integral invariant, instead inducing an anomaly. The relation to operator techniques and ordering problems is discussed, and special attention is paid to incorporation of the initial and final states of the transition element into the boundary conditions of the problem. Classical canonical transformations are developed to render an arbitrary power potential cyclic. The resulting Hamiltonian is analyzed as a quantum system to show its relation to known quantum mechanical results. A perturbative argument is used to suppress ordering related terms in the transformed Hamiltonian in the event that the classical canonical transformation leads to a nonquadratic cyclic Hamiltonian. The associated anomalies are analyzed to yield general methods to evaluate the path integral's prefactor for such systems. The methods are applied to several systems, including linear and quadratic potentials, the velocity-dependent potential, and the time-dependent harmonic oscillator.Comment: 28 pages, LaTe

Circular 64

Treatment of Alaska-produced food products by ionizing radiation may benefit the seafood and agricultural industries and the Alaskan consumer. A feasibility study to evaluate the potential social and economic benefits and risks as well as the costs of using the process in Alaska on Alaskan products is being coordinated by the Institute of Northern Engineering. A research and development project to determine effects on the quality o f Alaskan products could be the next phase in the introduction o f a new food-preservation technique to Alaska

Recent advances in coding theory for near error-free communications

Channel and source coding theories are discussed. The following subject areas are covered: large constraint length convolutional codes (the Galileo code); decoder design (the big Viterbi decoder); Voyager's and Galileo's data compression scheme; current research in data compression for images; neural networks for soft decoding; neural networks for source decoding; finite-state codes; and fractals for data compression

Nanosecond electric pulses penetrate the nucleus and enhance speckle formation

Nanosecond electric pulses generate nanopores in the interior membranes of cells and modulate cellular functions. Here, we used confocal microscopy and flow cytometry to observe Smith antigen antibody (Y12) binding to nuclear speckles, known as small nuclear ribonucleoprotein particles (snRNPs) or intrachromatin granule clusters (IGCs), in Jurkat cells following one or five 10 ns, 150 kV/cm pulses. Using confocal microscopy and flow cytometry, we observed changes in nuclear speckle labeling that suggested a disruption of pre-messenger RNA splicing mechanisms. Pulse exposure increased the nuclear speckled substructures by 2.5-fold above basal levels while the propidium iodide (PI) uptake in pulsed cells was unchanged. The resulting nuclear speckle changes were also cell cycle dependent. These findings suggest that 10 ns pulses directly influenced nuclear processes, such as the changes in the nuclear RNA–protein complexes

Physical activity patterns in urban neighbourhood parks: Insights from a multiple case study

Background: Many characteristics of urban parks and neighbourhoods have been linked to patterns of physical activity, yet untangling these relationships to promote increased levels of physical activity presents methodological challenges. Based on qualitative and quantitative data, this article describes patterns of activity within urban parks and the socio-demographic characteristics of park visitors. It also accounts for these patterns in relation to the attributes of parks and their surrounding neighbourhoods.Methods. A multiple case study was undertaken that incorporated quantitative and qualitative data derived from first-hand observation in a purposive sample of four urban parks. Quantitative data, based on direct observation of visitors' patterns of use and socio-demographic characteristics, were collected using a structured instrument. Differences in frequencies of observed activities and socio-demographic characteristics of visitors were compared between the four parks. Qualitative data, based on direct observation of park characteristics and patterns of use, were generated through digital photography and analyzed through captioning. Quantitative data on patterns in activity and socio-demographic characteristics were synthesized with the qualitative data on park and usage characteristics.Results: A comprehensive portrait of each park in the study was generated. Activity types (sedentary, walking, dog-related, cycling, and play), patterns of park use (time of day, day of week), and socio-demographic characteristics (age group, social group) differed between the four parks. Patterns in park use and activity appeared to be associated with socio-demographic characteristics of the surrounding neighbourhoods as well as the physical and social environmental characteristics specific to each park.Conclusions: Both park and neighbourhood characteristics influence patterns of use and physical activity within parks. The study findings suggest that socio-demographic characteristics of neighbourhoods surrounding parks need be considered in planning, development and management. Engaging local communities could help planners to develop and update urban parks in ways that reflect the needs and characteristics of community residents and, in turn, encourage visits and more physical activity amongst visitors

Invariant imbedding theory of mode conversion in inhomogeneous plasmas. II. Mode conversion in cold, magnetized plasmas with perpendicular inhomogeneity

A new version of the invariant imbedding theory for the propagation of coupled waves in inhomogeneous media is applied to the mode conversion of high frequency electromagnetic waves into electrostatic modes in cold, magnetized and stratified plasmas. The cases where the external magnetic field is applied perpendicularly to the direction of inhomogeneity and the electron density profile is linear are considered. Extensive and numerically exact results for the mode conversion coefficients, the reflectances and the wave electric and magnetic field profiles inside the inhomogeneous plasma are obtained. The dependences of mode conversion phenomena on the magnitude of the external magnetic field, the incident angle and the wave frequency are explored in detail.Comment: 11 figures, to be published in Physics of Plasma

Scale-dependent Galaxy Bias

We present a simple heuristic model to demonstrate how feedback related to the galaxy formation process can result in a scale-dependent bias of mass versus light, even on very large scales. The model invokes the idea that galaxies form initially in locations determined by the local density field, but the subsequent formation of galaxies is also influenced by the presence of nearby galaxies that have already formed. The form of bias that results possesses some features that are usually described in terms of stochastic effects, but our model is entirely deterministic once the density field is specified. Features in the large-scale galaxy power spectrum (such as wiggles that might in an extreme case mimic the effect of baryons on the primordial transfer function) could, at least in principle, arise from spatial modulations of the galaxy formation process that arise naturally in our model. We also show how this fully deterministic model gives rise to apparently stochasticity in the galaxy distribution.Comment: 14 pages, 2 figures, typos corrected, discussion added and references corrected; matches version accepted by JCA

Prognostic Significance of Growth Kinetics in Newly Diagnosed Glioblastomas Revealed by Combining Serial Imaging with a Novel Biomathematical Model

Glioblastomas (GBMs) are the most aggressive primary brain tumors characterized by their rapid proliferation and diffuse infiltration of the brain tissue. Survival patterns in patients with GBM have been associated with a number of clinico-pathologic factors, including age and neurological status, yet a significant quantitative link to in vivo growth kinetics of each glioma has remained elusive. Exploiting a recently developed tool for quantifying glioma net proliferation and invasion rates in individual patients using routinely available magnetic resonance images (MRIs), we propose to link these patient-specific kinetic rates of biological aggressiveness to prognostic significance. Using our biologically-based mathematical model for glioma growth and invasion, examination of serial pre-treatment MRIs of 32 GBM patients allowed quantification of these rates for each patient’s tumor. Survival analyses revealed that even when controlling for standard clinical parameters (e.g., age, KPS) these model-defined parameters quantifying biologically aggressiveness (net proliferation and invasion rates) were significantly associated with prognosis. One hypothesis generated was that the ratio of the actual survival time after whatever therapies were employed to the duration of survival predicted (by the model) without any therapy would provide a “Therapeutic Response Index” (TRI) of the overall effectiveness of the therapies. The TRI may provided important information, not otherwise available, as to the effectiveness of the treatments in individual patients. To our knowledge, this is the first report indicating that dynamic insight from routinely obtained pre-treatment imaging may be quantitatively useful in characterizing survival of individual patients with GBM. Such a hybrid tool bridging mathematical modeling and clinical imaging may allow for statifying patients for clinical studies relative to their pretreatment biological aggressiveness

Hybrid Meson Decay Phenomenology

The phenomenology of a newly developed model of hybrid meson decay is developed. The decay mechanism is based on the heavy quark expansion of QCD and the strong coupling flux tube picture of nonperturbative glue. A comprehensive list of partial decay widths of a wide variety of light, $s\bar s$, $c\bar c$, and $b \bar b$ hybrid mesons is presented. Results which appear approximately universal are highlighted along with those which distinguish different hybrid decay models. Finally, we examine several interesting hybrid candidates in detail.Comment: 37 pages, 2 figures, 6 tables, Revte