Fluorescence in situ hybridization of three oncogenes on a leiomyoma

Using fluorescence in situ hybridization technique, expression of three oncogenes, C-myc, RARa, and cyclin-D was tested on a uterine leiomyoma. C-myc and RARa were amplified in approximately 30% and 90% of the cells, respectively. Numerous small signals of C-myc were indicative of the presence of double minutes. Amplification of RARa is being reported for the first time in a leiomyoma. Cyclin-D was normal in diploid cells while it was highly amplified in polyploid cells. Low levels of amplified C-myc and cyclin-D cells seem to be the reason for this tumor to be benign, while RARa could not be effective without the association of some other gene such as PML. Information presented here are significant toward developing new curative strategies such as gene-specific drugs and molecular manipulation to stop the activity of cancer gene. Further study may elucidate that how fibroids grow and maintain their rare benign nature.     

Data Acquisition System for Time-Resolved Muscle Experiments

A versatile data acquisition system is described for use in collecting time resolved X-ray diffraction data from contracting muscle; it has sufficient flexibility to allow a number of different types of detector systems to be interfaced conveniently, though primarily intended for use with a high count rate Multiwire Linear Detector. Interactive analysis software to process the large volume of data obtained from such experiments are described for use on a VAX 780.     

Experimental observation of the improvement in MTF from backthinning a CMOS direct electron detector

The advantages of backthinning monolithic active pixel sensors (MAPS) based on complementary metal oxide semiconductor (CMOS) direct electron detectors for electron microscopy have been discussed previously; they include better spatial resolution (modulation transfer function or MTF) and efficiency at all spatial frequencies (detective quantum efficiency or DQE). It was suggested that a ‘thin’ CMOS detector would have the most outstanding properties [1], [2] and [3] because of a reduction in the proportion of backscattered electrons. In this paper we show, theoretically (using Monte Carlo simulations of electron trajectories) and experimentally that this is indeed the case.     

Electron imaging with Medipix2 hybrid pixel detector

The electron imaging performance of Medipix2 is described. Medipix2 is a hybrid pixel detector composed of two layers. It has a sensor layer and a layer of readout electronics, in which each 55 microm x 55 microm pixel has upper and lower energy discrimination and MHz rate counting. The sensor layer consists of a 300 microm slab of pixellated monolithic silicon and this is bonded to the readout chip. Experimental measurement of the detective quantum efficiency, DQE(0) at 120 keV shows that it can reach approximately 85% independent of electron exposure, since the detector has zero noise, and the DQE(Nyquist) can reach approximately 35% of that expected for a perfect detector (4/pi(2)). Experimental measurement of the modulation transfer function (MTF) at Nyquist resolution for 120 keV electrons using a 60 keV lower energy threshold, yields a value that is 50% of that expected for a perfect detector (2/pi). Finally, Monte Carlo simulations of electron tracks and energy deposited in adjacent pixels have been performed and used to calculate expected values for the MTF and DQE as a function of the threshold energy. The good agreement between theory and experiment allows suggestions for further improvements to be made with confidence. The present detector is already very useful for experiments that require a high DQE at very low doses.     

Images of paraffin monolayer crystals with perfect contrast: minimization of beam-induced specimen motion

Quantitative analysis of electron microscope images of organic and biological two-dimensional crystals has previously shown that the absolute contrast reached only a fraction of that expected theoretically from the electron diffraction amplitudes. The accepted explanation for this is that irradiation of the specimen causes beam-induced charging or movement, which in turn causes blurring of the image due to image or specimen movement. In this paper, we used three different approaches to try to overcome this image-blurring problem in monolayer crystals of paraffin. Our first approach was to use an extreme form of spotscan imaging, in which a single image was assembled on film by the successive illumination of up to 50,000 spots, each of a diameter of around 7 nm. The second approach was to use the Medipix II detector with its zero-noise readout to assemble a time-sliced series of images of the same area in which each frame from a movie with up to 400 frames had an exposure of only 500 electrons. In the third approach, we simply used a much thicker carbon support film to increase the physical strength and conductivity of the support. Surprisingly, the first two methods involving dose fractionation in space or time produced only partial improvements in contrast whereas the third approach produced many virtually perfect images, where the absolute contrast predicted from the electron diffraction amplitudes was observed in the images. We conclude that it is possible to obtain consistently almost perfect images of beam-sensitive specimens if they are attached to an appropriately strong and conductive support; however great care is needed in practice and the problem remains of how to best image ice-embedded biological structures in the absence of a strong, conductive support film.     

Digitisation of electron microscope films: six useful tests applied to three film scanners

A series of simple tests have been used to measure the performance of flat-bed film scanners suitable for digitisation of electron micrographs. Two of the film scanners evaluated are commercially available and one has been constructed in the laboratory paying special attention to the needs of the electron microscopist. The tests may be useful for others.     

Relativistic modelling of a superdense star containing a charged perfect fluid

The paper presents a variety of classes of interior solutions of the Einstein-Maxwell field equations for a static, spherically symmetric distribution of a charged fluid of well-behaved nature. They describe perfect fluid balls with positive finite central pressure and density; their ratio is less than one (c = 1), and the causality condition is obeyed at the center. The outmarch of pressure, density, pressuredensity ratio and the adiabatic speed of sound is a monotonic decrease, in a physically appealing manner. A certain class of these well-behaved solutions is studied extensively. For this class, the mass of the configuration is maximized. In particular, for a surface density ?? _b = 2×10¹⁴ g/cm³ we obtain a star with a maximummass of 3.47M _??, a radius of 15.21 km and the central redshift 1.014385.     

Modelling and control of chaotic processes through their Bifurcation Diagrams generated with the help of Recurrent Neural Network models: Part 1—simulation studies

Many real-world processes tend to be chaotic and also do not lead to satisfactory analytical modelling. It has been shown here that for such chaotic processes represented through short chaotic noisy time-series, a multi-input and multi-output recurrent neural networks model can be built which is capable of capturing the process trends and predicting the future values from any given starting condition. It is further shown that this capability can be achieved by the Recurrent Neural Network model when it is trained to very low value of mean squared error. Such a model can then be used for constructing the Bifurcation Diagram of the process leading to determination of desirable operating conditions. Further, this multi-input and multi-output model makes the process accessible for control using open-loop/closed-loop approaches or bifurcation control etc. All these studies have been carried out using a low dimensional discrete chaotic system of Hénon Map as a representative of some real-world processes.     

Enhanced imaging in low dose electron microscopy using electron counting

We compare the direct electron imaging performance at 120 keV of a monolithic active pixel sensor (MAPS) operated in a conventional integrating mode with the performance obtained when operated in a single event counting mode. For the combination of sensor and incident electron energy used here, we propose a heuristic approach with which to process the single event images in which each event is renormalised to have an integrated weight of unity. Using this approach we find enhancements in the Nyquist frequency modulation transfer function (MTF) and detective quantum efficiency (DQE) over the corresponding integrating mode values by factors of 8 and 3, respectively.     

Characteristics of the surfaces obtained in electro-discharge machining

According to the established thermal theories on electro-discharge machining (edm), the size of the craters produced in edm is proportional to the discharge energy, which is equal to the product of mean pulse current and pulse duration for a constant gap voltage. As a practical edm surface is a random superposition of such craters, the behaviour of the surfaces largely depends on the two important parameters, pulse current and pulse duration. With the help of multiple linear regression analysis, the effect of pulse duration and pulse current on the surface topography parameters R_q and β* has been studied. sem photomicrographs have been taken in support of the qualitative evidence