An Optimised High Current Impulse Source

Starting from a predefined 8/20 µs impulse current, the design and construction of an impulse current source is derived. In the first step an equivalent circuit is defined that meets exactly the predefined impulse current. In the next step the components that are required to realise the equivalent circuit diagram are chosen and modelled by their equivalent circuit diagrams. As far as the components do not show ideal behaviour, the stray parameters if the components are determined by calculation and measurement. Further on, the construction parameters for the geometric structure of the plant are derived from the equivalent circuit diagram of the entire impulse generating network. Finally it is shown that the measured current of the realised impulse current generator meets exactly the desired predefined impulse current

Purposive Design of a Magnetic Sheet Metal Forming Facility

This paper is about the identification of lumped elements within an electric circuit diagram in the context of electromagnetic sheet metal forming. Based on fundamental physical considerations the forming coil and its workpiece can be modeled as a transformer, which is loaded on its secondary side by a resistor. A systematic oriented design process relating to an aimed at purpose is introduced in order to avoid time extensive trial-anderror methods. Based upon the theory of electromagnetic field equations, the complex impedance of the sheet metal is analytically identified as a function of the radial component. Based on the introduction of a force equivalent quantity, ways of designing and optimizing the remaining free parameters are presented. Thus, a design process for a forming facility is possible as the desired electromagnetic force can be characterized by the currents running through the forming coil and the sheet metal

Optical Position and Time Resolved Measurement of Magnetic Field Distribution in High Speed Metal Forming

In the area of the position and time resolved measurement of the magnetic field distribution in small gaps between workpieces and coils in high-speed sheet metal forming optical sensors are predestined to be integrated into the very small geometries of experimental setups. Optical sensors for current measurement based on the magneto-optic Faraday effect are well known for a long time. This effect can also be used for the direct measurement of magnetic fields. For the use in electromagnetic high-speed metal forming applications, only very small field probes are probable. The measurement of axial symmetric fields can be achieved with two connected fibres with different Verdet constants. They solve the problem with the not given measurement value, which occurs by the use of only one fibre because of its closed integral domain. A continuous time signal of the magnetic field can be calculated for discrete regions. Likewise, it is possible to employ miniature fibre-optic magnetic field point sensors for the field determination in the gap of an electromagnetic high-speed forming device. It is necessary to examine the influence on the polarisation state and the intensity of the light in a fibre. There are two different sensors shown in this paper. One is based on a piece of flint glass fibre spliced between two polarising fibres, and the other sensor arrangement consists of two glued SiO_2 blocks. A workbench for assembling of fibre-optic sensors using the splice technology has been constructed and will be presented. First trial measurements of the magnetic field, compared to the causing current, show the functionality of these kinds of optical sensors and are discussed under the aspect of optimisation

Assessing the Effective Energy for Magnetic Forming Processes by Means of Measurements and Numerical Calculation

The efficiency of magnetic sheet metal forming processes is strongly depending on the facility s overall design. This mainly includes the geometric layout of forming tool, work piece and matrix but, however, will also expect the energy storage device being taken into consideration. Apart from field theoretic models the energy storage is describable by its terminal traits which the electric load - tool coil and work piece - is connected to. The paper presents a measuring method for the tool coil s terminal quantities, current i(t) and voltage u(t), which are used to provide the electric power p(t) being transferred to the load. Thus, it is possible to determine the entire energy which is dissipated by the work piece, provided that the coil s resistance is known. Besides the measurement, this approach is supported by numerical calculation intending to take a closer look at the inner losses of the work piece which are not accessible from measuring the system s terminal traits directly. Dividable into separate parts of the total energy, this information is applied to assess the forming process by means of the facility s energetic performance and to draw an overall energy balance

Imaging of THz waves in 2D photonic crystal structures embedded in a slab waveguide

We present space- and time-resolved simulations and measurements of single-cycle terahertz (THz) waves propagating through two-dimensional (2D) photonic crystal structures embedded in a slab waveguide. Specifically, we use a plane wave expansion technique to calculate the band structure and a time-dependent finite-element method to simulate the temporal evolution of the THz waves. Experimentally, we measure the space–time evolution of the THz waves through a coherent time-resolved imaging method. Three different structures are laser machined in LiNbO3 crystal slabs and analyzing the transmitted as well as the reflected THz waveforms allows determination of the bandgaps. Comparing the results with the calculated band diagrams and the time-dependent simulations shows that the experiments are consistent with 3D simulations, which include the slab waveguide geometry, the birefringence of the material, and a careful analysis of the excited modes within the band diagrams.Swiss National Science Foundation (project no. 200020-119934

Menthol Suppresses Nicotinic Acetylcholine Receptor Functioning in Sensory Neurons via Allosteric Modulation

In this study, we have investigated how the function of native and recombinant nicotinic acetylcholine receptors (nAChRs) is modulated by the monoterpenoid alcohol from peppermint (−) menthol. In trigeminal neurons (TG), we found that nicotine (75 μM)-activated whole-cell currents through nAChRs were reversibly reduced by menthol in a concentration-dependent manner with an IC50 of 111 μM. To analyze the mechanism underlying menthol's action in more detail, we used single channel and whole-cell recordings from recombinant human α4β2 nAChR expressed in HEK tsA201 cells. Here, we found a shortening of channel open time and a prolongation of channel closed time, and an increase in single channel amplitude leading in summary to a reduction in single channel current. Furthermore, menthol did not affect nicotine's EC50 value for currents through recombinant human α4β2 nAChRs but caused a significant reduction in nicotine's efficacy. Taken together, these findings indicate that menthol is a negative allosteric modulator of nAChRs

Evolution of Thermal Response Properties in a Cold-Activated TRP Channel

Animals sense changes in ambient temperature irrespective of whether core body temperature is internally maintained (homeotherms) or subject to environmental variation (poikilotherms). Here we show that a cold-sensitive ion channel, TRPM8, displays dramatically different thermal activation ranges in frogs versus mammals or birds, consistent with variations in these species' cutaneous and core body temperatures. Thus, somatosensory receptors are not static through evolution, but show functional diversity reflecting the characteristics of an organism's ecological niche

Search for new phenomena in final states with an energetic jet and large missing transverse momentum in pp collisions at √ s = 8 TeV with the ATLAS detector

Results of a search for new phenomena in final states with an energetic jet and large missing transverse momentum are reported. The search uses 20.3 fb−1 of √ s = 8 TeV data collected in 2012 with the ATLAS detector at the LHC. Events are required to have at least one jet with pT > 120 GeV and no leptons. Nine signal regions are considered with increasing missing transverse momentum requirements between Emiss T > 150 GeV and Emiss T > 700 GeV. Good agreement is observed between the number of events in data and Standard Model expectations. The results are translated into exclusion limits on models with either large extra spatial dimensions, pair production of weakly interacting dark matter candidates, or production of very light gravitinos in a gauge-mediated supersymmetric model. In addition, limits on the production of an invisibly decaying Higgs-like boson leading to similar topologies in the final state are presente

Estrogen regulation of TRPM8 expression in breast cancer cells

<p>Abstract</p> <p>Background</p> <p>The calcium-permeable cation channel TRPM8 (melastatin-related transient receptor potential member 8) is over-expressed in several cancers. The present study aimed at investigating the expression, function and potential regulation of TRPM8 channels by ER alpha (estrogen receptor alpha) in breast cancer.</p> <p>Methods</p> <p>RT-PCR, Western blot, immuno-histochemical, and siRNA techniques were used to investigate TRPM8 expression, its regulation by estrogen receptors, and its expression in breast tissue. To investigate the channel activity in MCF-7 cells, we used the whole cell patch clamp and the calcium imaging techniques.</p> <p>Results</p> <p>TRPM8 channels are expressed at both mRNA and protein levels in the breast cancer cell line MCF-7. Bath application of the potent TRPM8 agonist Icilin (20 μM) induced a strong outwardly rectifying current at depolarizing potentials, which is associated with an elevation of cytosolic calcium concentration, consistent with established TRPM8 channel properties. RT-PCR experiments revealed a decrease in TRPM8 mRNA expression following steroid deprivation for 48 and 72 hours. In steroid deprived medium, addition of 17-beta-estradiol (E₂, 10 nM) increased both TRPM8 mRNA expression and the number of cells which respond to Icilin, but failed to affect the Ca²⁺entry amplitude. Moreover, silencing ERα mRNA expression with small interfering RNA reduced the expression of TRPM8. Immuno-histochemical examination of the expression of TRPM8 channels in human breast tissues revealed an over-expression of TRPM8 in breast adenocarcinomas, which is correlated with estrogen receptor positive (ER⁺) status of the tumours.</p> <p>Conclusion</p> <p>Taken together, these results show that TRPM8 channels are expressed and functional in breast cancer and that their expression is regulated by ER alpha.</p