Argon metastable dynamics in a filamentary jet micro-discharge at atmospheric pressure

Space and time resolved concentrations of Ar ($^{3}P_2$) metastable atoms at the exit of an atmospheric pressure radio-frequency micro-plasma jet were measured using tunable diode laser absorption spectroscopy. The discharge features a coaxial geometry with a hollow capillary as an inner electrode and a ceramic tube with metal ring as outer electrode. Absorption profiles of metastable atoms as well as optical emission measurements reveal the dynamics and the filamentary structure of the discharge. The average spatial distribution of Ar metastables is characterized with and without a target in front of the jet, showing that the target potential and therewith the electric field distribution substantially changes the filaments' expansion. Together with the detailed analysis of the ignition phase and the discharge's behavior under pulsed operation, the results give an insight into the excitation and de-excitation mechanisms

Dielectric properties of charge ordered LuFe2O4 revisited: The apparent influence of contacts

We show results of broadband dielectric measurements on the charge ordered, proposed to be mul- tiferroic material LuFe2O4. The temperature and frequency dependence of the complex permittivity as investigated for temperatures above and below the charge-oder transition near T_CO ~ 320 K and for frequencies up to 1 GHz can be well described by a standard equivalent-circuit model considering Maxwell-Wagner-type contacts and hopping induced AC-conductivity. No pronounced contribution of intrinsic dipolar polarization could be found and thus the ferroelectric character of the charge order in LuFe2O4 has to be questioned.Comment: 4 pages, 3 figure

Impurity intrusion in radio-frequency micro-plasma jets operated in ambient air

Space and time resolved concentrations of helium metastable atoms in an atmospheric pressure radio-frequency micro-plasma jet were measured using tunable diode laser absorption spectroscopy. Spatial profiles as well as lifetime measurements show significant influences of air entering the discharge from the front nozzle and of impurities originating from the gas supply system. Quenching of metastables was used to deduce quantitative concentrations of intruding impurities. The impurity profile along the jet axis was determined from optical emission spectroscopy as well as their dependance on the feed gas flow through the jet.Comment: Journal of Physics D: Applied Physics (accepted), 6 page

Nanofabrication of spin-transfer torque devices by a PMMA mask one step process: GMR versus single layer devices

We present a method to prepare magnetic spin torque devices of low specific resistance in a one step lithography process. The quality of the pillar devices is demonstrated for a standard magnetic double layer device. For single layer devices, we found hysteretic switching and a more complex dynamical excitation pattern in higher fields. A simple model to explain the resistance spikes is presented.Comment: 22 pages, 6 figures, submitted to J. Appl. Phy

Application of a mode-locked fiber laser for highly time resolved broadband absorption spectroscopy and laser-assisted breakdown on micro-plasmas

Cataloged from PDF version of article.Absorption spectroscopy is known to be a powerful tool to gain spatially and temporally resolved information on excited and reactive species in a plasma discharge. Furthermore, the interaction of the discharge with short intense laser pulses can trigger the ignition and the transition into other transient states of the plasma. In this context laser-assisted 'pump-probe' experiments involving simultaneously generated supercontinuum radiation yield highly temporally resolved and spatially well-defined information on the transient phenomena. In this paper we demonstrate the possibility for 'pump-probe' experiments by initiating breakdown on a picosecond time scale ('pump') with a high-power beam and measuring the broadband absorption with the simultaneously provided supercontinuum ('probe'). Since both pulses are generated from the same mode-locked master oscillator, they have a strong level of synchronization

Context matters! The relationship between mother-reported family nutrition climate, general parenting, food parenting practices and children’s BMI

Background: Efforts to explain children’s nutrition behavior or weight often involve investigating the parent-child relationship, typically studying the associations between food parenting practices (FPPs) and child outcomes. However, these behaviors are embedded in a broader system: general parenting (GP, the general emotional climate at home), and the family health climate (an aspect of the broader family system in the context of health). In the current study, we combined the parent-child measures of parenting (FPPs and GP) and the nutritional dimension of the family health climate (family nutrition climate, FNC) to get a broader view of how these concepts are interrelated. The current study had two aims: predicting FPPs using GP and FNC as predictor variables, and investigating the relationship between FPPs and children’s weight in different groups of parents, based on low and high GP and FNC scores. Methods: We collected cross-sectional data via an online survey panel. Mothers of 267 children aged 5–12 years filled out a questionnaire assessing demographics (e.g., children’s weight and height), GP, FPPs, and FNC. Bivariate correlation coefficients were calculated between all constructs. Structural equation modeling was performed to test the hypothesized relationships between GP, FNC and FPPs. Hereafter, different groups of parents were identified, using median split, based on a low or high score on GP or a low or high score on FNC. Bivariate correlation coefficients were calculated between FPPs and children’s BMI z-score for these different groups. Results: GP and FNC were consistently positively correlated (all r’s ≥.177), and both concepts were positively associated with healthy FPPs (all r’s ≥.214). In families with a positive context (i.e. scoring high on GP and on FNC), healthy FPPs were associated with lower BMI z-scores of the children (r -.229). This association was not found for children with a more negative family context. Conclusions: FNC and GP are valuable additional concepts to investigate relationships between FPPs and child outcomes. We recommend that more studies, next to investigating the parent-child system, include a measure of the broader family system, in order to get a broader view of the mechanisms explaining child health behaviors and weight status

The Oscillatory Behavior of the High-Temperature Expansion of Dyson's Hierarchical Model: A Renormalization Group Analysis

We calculate 800 coefficients of the high-temperature expansion of the magnetic susceptibility of Dyson's hierarchical model with a Landau-Ginzburg measure. Log-periodic corrections to the scaling laws appear as in the case of a Ising measure. The period of oscillation appears to be a universal quantity given in good approximation by the logarithm of the largest eigenvalue of the linearized RG transformation, in agreement with a possibility suggested by K. Wilson and developed by Niemeijer and van Leeuwen. We estimate $\gamma$ to be 1.300 (with a systematic error of the order of 0.002) in good agreement with the results obtained with other methods such as the $\epsilon$-expansion. We briefly discuss the relationship between the oscillations and the zeros of the partition function near the critical point in the complex temperature plane.Comment: 21 pages, 10 Postcript figures, latex file, uses revte

Targeting the Mechanisms of Resistance to Chemotherapy and Radiotherapy with the Cancer Stem Cell Hypothesis

Despite advances in treatment, cancer remains the 2nd most common cause of death in the United States. Poor cure rates may result from the ability of cancer to recur and spread after initial therapies have seemingly eliminated detectable signs of disease. A growing body of evidence supports a role for cancer stem cells (CSCs) in tumor regrowth and spread after initial treatment. Thus, targeting CSCs in combination with traditional induction therapies may improve treatment outcomes and survival rates. Unfortunately, CSCs tend to be resistant to chemo- and radiation therapy, and a better understanding of the mechanisms underlying CSC resistance to treatment is necessary. This paper provides an update on evidence that supports a fundamental role for CSCs in cancer progression, summarizes potential mechanisms of CSC resistance to treatment, and discusses classes of drugs currently in preclinical or clinical testing that show promise at targeting CSCs