Microwave-induced magnetotransport phenomena in two-dimensional electron systems: Importance of electrodynamic effects

We discuss possible origins of recently discovered microwave induced photoresistance oscillations in very-high-electron-mobility two-dimensional electron systems. We show that electrodynamic effects -- the radiative decay, plasma oscillations, and retardation effects, -- are important under the experimental conditions, and that their inclusion in the theory is essential for understanding the discussed and related microwave induced magnetotransport phenomena.Comment: 5 pages, including 2 figures and 1 tabl

The possibility of a metal insulator transition in antidot arrays induced by an external driving

It is shown that a family of models associated with the kicked Harper model is relevant for cyclotron resonance experiments in an antidot array. For this purpose a simplified model for electronic motion in a related model system in presence of a magnetic field and an AC electric field is developed. In the limit of strong magnetic field it reduces to a model similar to the kicked Harper model. This model is studied numerically and is found to be extremely sensitive to the strength of the electric field. In particular, as the strength of the electric field is varied a metal -- insulator transition may be found. The experimental conditions required for this transition are discussed.Comment: 6 files: kharp.tex, fig1.ps fig2.ps fi3.ps fig4.ps fig5.p

Edge and bulk effects in the Terahertz-photoconductivity of an antidot superlattice

We investigate the Terahertz(THz)-response of a square antidot superlattice by means of photoconductivity measurements using a Fourier-transform-spectrometer. We detect, spectrally resolved, the cyclotron resonance and the fundamental magnetoplasmon mode of the periodic superlattice. In the dissipative transport regime both resonances are observed in the photoresponse. In the adiabatic transport regime, at integer filling factor $\nu =2$, only the cyclotron resonance is observed. From this we infer that different mechanisms contribute to converting the absorption of THz-radiation into photoconductivity in the cyclotron and in the magnetoplasmon resonances, respectively.Comment: 15 pages, 4 figures, submitted to Phys. Rev.

Metal-insulator transitions in cyclotron resonance of periodic nanostructures due to avoided band crossings

A recently found metal-insulator transition in a model for cyclotron resonance in a two-dimensional periodic potential is investigated by means of spectral properties of the time evolution operator. The previously found dynamical signatures of the transition are explained in terms of avoided band crossings due to the change of the external electric field. The occurrence of a cross-like transport is predicted and numerically confirmed

Targeting the MAPK7/MMP9 axis for metastasis in primary bone cancer

Metastasis is the leading cause of cancer related death. This multistage process involves contribution from both tumour cells and the tumour stroma to release metastatic cells into the circulation. Circulating tumour cells (CTCs) survive circulatory cytotoxicity, extravasate and colonise secondary sites effecting metastatic outcome. Reprogramming the transcriptomic landscape is a metastatic hallmark but detecting underlying master regulators that drive pathological gene expression is a key challenge, especially in childhood cancer. Here we used whole tumour plus single cell RNA sequencing in primary bone cancer and CTCs to perform weighted gene co-expression network analysis to systematically detect coordinated changes in metastatic transcript expression. This approach with comparisons applied to data collected from cell line models, clinical samples and xenograft mouse models revealed MAPK7/MMP9 signalling as a driver for primary bone cancer metastasis. RNAi knockdown of MAPK7 reduces proliferation, colony formation, migration, tumour growth, macrophage residency/polarisation and lung metastasis. Parallel to these observations were reduction of activated interleukins IL1B, IL6, IL8 plus mesenchymal markers VIM and VEGF in response to MAPK7 loss. Our results implicate a newly discovered, multidimensional MAPK7/MMP9 signalling hub in primary bone cancer metastasis that is clinically actionable

Simulation of an oxic-settling-anaerobic pilot plant operated under real conditions using the activated sludge model no.2d

Oxic-settling-anaerobic (OSA) process has been introduced into the treatment line of wastewater in order to upgrade activated sludge processes and to reduce the production of excess sludge. The aim of the present study was to simulate the performance of an OSA pilot plant by implementing the Activated Sludge Model No.2d (ASM2d) into a mathematical modelling software (BioWin). The stepwise calibration, performed both by off-line experiments and software dynamic calibration, was carried out in a heuristic way, adjusting the parameters values that showed a major influence to the effluent and internal concentrations. All the reduction factors introduced into ASM2d to simulate the processes occurring in anoxic and anaerobic conditions were lowered in order to reproduce the concentrations of interest. In addition, the values of parameters of the PAOs (polyphosphate accumulating organisms)-related process (namely qPHA and YPO4 ) were found lower than those usually adopted. In general, theoretical results were in good agreement with the experimental data obtained from plant’s operation, showing an accurate predictive capacity of the model. Good performance was achieved considering the phosphorus removal related process, while some failures were detected in COD and ammonia simulations

Factors associated with back pain in nursing staff: A survey in Athens, Greece

Factors associated with self-reported back pain were investigated using questionnaire data on 407 female nurses from a large hospital in Athens, Greece. Factor analysis was used to construct indices of pain and its impact on normal life, and also to summarize work load descriptions. Pain factors were examined in relation to work load and personal characteristics by logistic regression. Statistically significant items, in relation both to pain and impact, were the existence of previous back injury, self-reported headaches and the 'carrying and lifting' factor of work load which principally included moving equipment. Age, height and weight were not associated with back pain. Compared to a similar study by Harber and colleagues in California, United States of Amercia, the factors associated with back pain were quite similar in this study even though the prevalence of back pain was much higher among Greek nurses and their work load was physically much more demanding

Long-term effects of levosimendan infusion on inflammatory processes and sFas in patients with severe heart failure.

BACKGROUND: The calcium sensitizer levosimendan improves myocardial contractility in patients with heart failure, although its effects on inflammation and apoptosis are unknown. AIM: To examine the effects of levosimendan on markers of inflammation and apoptosis, over a period of 30 d following a 24 h infusion, in patients with heart failure. METHODS: Thirty four patients with severe heart failure were randomised to receive a 24 h infusion of levosimendan or placebo, in a double-blind trial. Haemodynamic evaluation and blood sampling were performed at baseline, 24 h, 30 h, 48 h, 7 d and 30 d after the end of the infusion. RESULTS: Seven patients (1 levosimendan, 6 placebo), were excluded during follow-up. In the remaining 27 patients, levosimendan decreased serum IL-6 and sFAS, 24 h after the infusion (p<0.01 and p<0.05 vs baseline), an effect sustained for 7-30 d. Serum TNF-alpha and sTNF-R1 were decreased between 48 h (p<0.01 vs baseline for both) and 7 d (p<0.05 vs baseline for sTNF-R1) after infusion. Serum sTNF-R2 was decreased at 24 h (p<0.05 vs baseline) and remained lower than baseline for at least 7 d (p<0.05). CONCLUSIONS: These findings indicate that levosimendan decreases the expression of proinflammatory cytokines, TNF-alpha receptors and sFAS, immediately after infusion, an effect which persists for 7-30 d

Transport of pseudomonas putida in a 3-D bench scale experimental aquifer

Summarization: This study is focused on the transport of Pseudomonas (P.) putida bacterial cells in a 3-D model aquifer. The pilot-scale aquifer consisted of a rectangular glass tank with internal dimensions: 120 cm length, 48 cm width, and 50 cm height, carefully packed with well-characterized quartz sand. The P. putida decay was adequately represented by a firstorder model. Transport experiments with a conservative tracer and P. putida were conducted to characterize the aquifer and to investigate the bacterial behavior during transport in water saturated porous media. A 3-D, finite-difference numerical model for bacterial transport in saturated, homogeneous porous media was developed and was used to successfully fit the experimental data. Furthermore, theoretical interaction energy calculations suggested that the extended-DLVO theory seems to predict bacteria attachment onto the aquifer sand better than the classical DLVO theory.Παρουσιάστηκε στο: Transport in Porous Medi