Possible application of memristors in ESD protection

Memristors as fundamental two-terminal electric circuit elements can be miniaturised to extreme extents. However like other electronic devices memristors can have application in the field of electrical engineering as well, e.g. in the fields of over-current protection, over-voltage protection and EMC. This paper proposes an application opportunity of memristors in ESD protection. Based on their purely dissipative character, these devices can usefully co-operate with ceramic capacitors having no ability to dissipate the energy of ESD surges. A type of structure of memristors for ESD protection purposes and a SPICE model are proposed.     

Compression of long-cavity Ti:sapphire oscillator pulses with large-mode-area photonic crystal fibers

Motivated by the pulse compression challenge of novel long-cavity, high-pulse-energy Ti:sapphire laser oscillators, we report on ~280 nm supercontinuum generation and 4.5-times compression of close to transform limited, high-energy oscillator pulses using different large-mode-area photonic crystal fibers and standard chirped mirrors. As input, we used pulses of a long-cavity Ti:sapphire oscillator with 190 nJ pulse energy, 70 fs pulse length and 3.6 MHz repetition rate. Compressed pulses at the fiber/compressor output had a duration of 15–18 fs with up to 100 nJ pulse energy representing as much as 53 % throughput for the fiber/chirped mirror system. Using transform-limited input pulses, we could use short fiber pieces and thus a simple, low-dispersion chirped mirror compressor comprised of one pair of mirrors.     

Direct observation of local distortion of a crystal lattice with picometer accuracy using atomic resolution neutron holography

We demonstrate that neutron holography permits us to extend the determination of atomic positions beyond nearest neighbors at least up to the fourth neighboring shell around cadmium probe atoms alloyed into a lead crystal. The accuracy achieved is sufficient to allow quantitative determination of displacements of atoms due to elastic distortions induced by impurity atoms. The atomic positions derived from the holographic data are in good agreement with those expected theoretically due to Friedel oscillations in this system. In addition, the atomic positions are in qualitative agreement with results obtained in an independent experiment studying the diffuse distortion scattering around Bragg peaks.     

Conservative spatial chaos of buckled elastic linkages

Buckling of an elastic linkage under general loading is investigated. We show that buckling is related to an initial value problem, which is always a conservative, area-preserving mapping, even if the original static problem is nonconservative. In some special cases, we construct the global bifurcation diagrams, and argue that their complicated structure is a consequence of spatial chaos. We characterize spatial chaos by the associated initial value problem's topological entropy, which turns out to be related to the number of buckled configurations.     

The external demagnetizing factor and the static characteristic loop

In this paper a proposal is put forward for the calculation of the shearing factor N_S linked to the well known, demagnetization coefficient N_D, from the data of a sheared saturation loop, obtained by a non-toroidal, open circuit hysteresis measurement. Following that, the paper illustrates the way to recover the real static loop data from an open circuit, measured data. The proposal is based on the hyperbolic model. The proposed method was illustrated on the tests carried out on two closed and open toroidal samples, mimicking the demagnetization effect of the open circuit VSM measurement, made of NO Fe–Si electrical steel sheets. These test results, presented here, agree very well with the calculated results, based on the hyperbolic modeling.     

Observation of a diamagnetic signal up to 132 K in a Tl−Ca−Ba−Cu−O compound

Tl–Ca–Ba–Cu–O compounds of the nominal composition of (1, 1, 1, 1) have been prepared from different starting materials and with the same heat treatment process. During the investigation of their properties a diamagnetic signal has been found up to the temperature of 132 K. This hints at the existence of a certain material content distributed into discrete superconducting domains. The parameters of it reflect a superstructure of the (2, 2, 2, 3) and (2, 1, 2, 2) compositions having a time-dependent behaviour. On the basis of the signal levels at 132 K and 4.2 K, the quantity of the high temperature superconducting material is about 0.01% of the total one at liquid He temperatures.     

Absolute resonance strengths in the $^{6,7}Li(\alpha, \gamma)^{10,11}B$ reactions

The absolute strengths of the keV resonance in the reaction and of the keV resonance in the reaction have been measured to meV and meV, respectively, in good agreement with previous values. These resonances can be used to measure the absolute acceptance of the recoil separator ERNA to a precision of about 10%.Received: 12 December 2003, Revised: 10 February 2004, Published online: 3 August 2004PACS: 24.30.-v Resonance reactions - 25.40.Lw Radiative capture - 26.20. + f Hydrostatic stellar nucleosynthesis     

Development of chemically modified glass surfaces for nucleic acid,protein and small molecule microarrays

Microarrays have become a widely used tool to investigate the living cell at different levels. DNA microarrays enable the expression analysis of thousand of genes simultaneously, while protein arrays investigate the properties and interactions of proteins with other proteins and with non-proteinaceous molecules. One crucial step in producing such microarrays is the permanent immobilization of samples on a solid surface. Our goal was to develop diverse linker systems capable of anchoring different biological samples, especially DNA and drug-like small molecules. We developed 6 different chemical surfaces having a 3-D-like linker system for biomolecule immobilization, and compared them to previously described immobilization strategies. The attachment chemistry utilizes the amino reactive properties of acrylic and epoxy functions. The capacity of the support was increased by creating a branching structure holding the reactive functions. The method of anchoring was investigated through a model reaction. From HPLC and mass spectrometry measurements we concluded that the covalent binding of DNA occurs through nucleobases. The tested systems offer the capability to permanently immobilize several biomolecular species in an array format.     

Elucidating a normal function of huntingtin by functional and microarray analysis of huntingtin-null mouse embryonic fibroblasts

Background

Multi-sensory integration is necessary for organisms to discriminate different environmental stimuli and thus determine behavior. Caenorhabditis elegans has 12 pairs of amphid sensory neurons, which are involved in generating behaviors such as thermotaxis toward cultivation temperature, and chemotaxis toward chemical stimuli. This arrangement of known sensory neurons and measurable behavioral output makes C. elegans suitable for addressing questions of multi-sensory integration in the nervous system. Previous studies have suggested that C. elegans can process different chemoattractants simultaneously. However, little is known about how these organisms can integrate information from stimuli of different modality, such as thermal and chemical stimuli.

Results

We studied the behavior of a population of C. elegans during simultaneous presentation of thermal and chemical stimuli. First, we examined thermotaxis within the radial temperature gradient produced by a feedback-controlled thermoregulator. Separately, we examined chemotaxis toward sodium chloride or isoamyl alcohol. Then, assays for simultaneous presentations of 15°C (colder temperature than 20°C room temperature) and chemoattractant were performed with 15°C-cultivated wild-type worms. Unlike the sum of behavioral indices for each separate behavior, simultaneous presentation resulted in a biased migration to cold regions in the first 10 min of the assay, and sodium chloride-regions in the last 40 min. However, when sodium chloride was replaced with isoamyl alcohol in the simultaneous presentation, the behavioral index was very similar to the sum of separate single presentation indices. We then recorded tracks of single worms and analyzed their behavior. For behavior toward sodium chloride, frequencies of forward and backward movements in simultaneous presentation were significantly different from those in single presentation. Also, migration toward 15°C in simultaneous presentation was faster than that in 15°C-single presentation.

Conclusion

We conclude that worms preferred temperature to chemoattractant at first, but preferred the chemoattractant sodium chloride thereafter. This preference was not seen for isoamyl alcohol presentation. We attribute this phase-dependent preference to the result of integration of thermosensory and chemosensory signals received by distinct sensory neurons.