Fetal MEG redistribution by projection operators

The fetal magnetoencephalogram (fMEG) is measured in the presence of large interference from the maternal and fetal magnetocardiograms. This interference can be efficiently attenuated by orthogonal projection of the corresponding spatial vectors. However, the projection operators redistribute the fMEG signal among sensors. Although redistribution can be readily accounted for in the forward solution, visual interpretation of the fMEG signal topography is made difficult. We have devised a general, model-independent method for correction of the redistribution effect that utilizes the assumption that we know in which channels the fMEG should be negligible (such channels are distant from the known fetal head position). In a simplified case where the fMEG can be explained by equivalent current dipoles, the correction can also be obtained from fitting the dipoles to the fMEG signal. The corrected fMEG signal topography then corresponds to the dipole forward solution, but without orthogonal projection. We illustrate the redistribution correction on an example of experimentally measured flash evoked fMEG.     

Spectral Response Model of Backside-Illuminated HgCdTe Detectors

Backside-illuminated HgCdTe detectors fabricated on thick CdZnTe substrates have an optical path such that the incident radiation traverses the antireflection (AR) coating layers, the thick CdZnTe substrate, and finally the different layers of the detector. Modeling the spectral response first involves a coherent calculation of the transmission and reflection of a multilayer AR coating on the backside of the CdZnTe substrate. Second, a coherent calculation is made of the reflection and transmission coefficients for the stack of detector materials including wavelength-dependent complex refractive indexes for the detector materials. Third, the transmission and reflection coefficients are then used in an incoherent calculation to account for the multiple reflections in the thick CdZnTe substrate. For the coherent calculations, a stack matrix is constructed from the multiplication of matrices that track the phase and amplitude of the waves propagating across interfaces and from one side of a layer to the other side. These calculations are combined to compute the spectral response and reflectance of the detector as a function of wavelength.     

Modeling of junction formation and drive-in in ion implanted HgCdTe

N-on-p junction formation and drive-in in ion implanted Hg_0.8Cd_0.2Te photodiodes have been studied. A model of the junction formation and drive-in processes has been developed that accounts for the variations in injected Hg interstitial concentration, background point defect and extrinsic doping levels, sample geometry, and annealing conditions. The limiting mechanisms controlling junction drive-in were investigated using the model. Experimental data showed the junction drive-in rate was proportional to the square root of time, indicating a diffusion limited process. The diffusion limited process is the result of a solubility limit for the Hg interstitial concentration. This limit is approximately the same value as that obtained for Hg interstitials in Hg saturated Hg_0.8Cd_0.2Te in type conversion and self-diffusion experiments (D_IC_I = 1.43 × 10₁₃exp(−.457 eV/ kT)*P_Hg).     

Birds of prey: identifying lexical irregularities in spam on Twitter

Wireless Networks - The advent of spam on social media platforms has lead to a number of problems not only for social media users but also for researchers mining social media data. While there has...     

Angle diversity and space diversity experiments on theSalton/Brawley hop

Space diversity and angle diversity experimental data have been collected over a three year period, using 64 quadrature amplitude modulation (QAM) radios, on the terrestrial microwave radio hop between Salton and Brawley in southern California. Both measured data and simulations have shown that the performance of angle diversity systems depends on the direction of transmission as well as the polarization of the signal. While this may also be true for space diversity, the effects of a finite spatial correlation length and a small signal-to-noise ratio significantly reduce the sensitivity of space diversity to the direction of propagation. Additionally, the performance of angle diversity is shown to depend upon the method used to implement angle diversity     

Motion coding of image primitives

We introduce an algorithm for matching stationary or moving image primitive lines between adjacent frames of a video sequence. Starting from local measures of proximity and similarity of shape, the algorithm computes the distance between pairs of primitives. It has strategies for dealing with broken lines and various kinds of connections between lines. The output of the algorithm is used to control a motion coding system, where only unmatched threads need be transmitted. The system can function in a simple conditional replenishment mode, or with motion compensation. Experimental results are reported showing an improvement of compression rate of 2:1 between intraframe primitivebased coding and motion-compensated primitive-based coding.     

Report of an IEEE Task Force?An IEEE Opinion on Research Needs for Biomedical Engineerng Systems

MORE than 200 years ago, our forefathers made note of man's inalienable rights to life, liberty, and the pursuit of happiness. To the engineering community (applied science in the service of man), these may be coincident with applications to medicine and biology (biomedical engineering), defense, and entertainment. Biomedical engineering research has the distinction, among these three missions, of not only contributing to the quality of human life through the industrial economy but also to life itself?the most fundamental concern of all people. It is through biomedical engineering research that we have been able to learn much concerning the functioning of living systems, and it is through such knowledge that we have been able to develop improved clinical diagnosis, monitoring, and treatment, including life-sustaining devices and aids to the handicapped. Each step represents an improvement in the quality of life, and each step forms the foundation upon which to gain new knowledge to improve upon earlier developments.     

A simple conceptual model for predicting the dissolution of phosphate rock in soils

Laboratory experimental and literature data were integrated to develop a simple, conceptual model to describe and predict the dissolution of a reactive phosphate rock (Gafsa phosphate rock, GPR) in soils. The model showed that initial solution Ca concentration strongly influences the time required for a single application of GPR (at 30 kgP ha^?1) to dissolve. The model predicts that all of the GPR will dissolve within a year of application in an unlimed, acid (pH_w 4.5) loam. However, if the soil has previously been limed to (pH_w 5.8, and contains permanent charge only, the model predicts that only about 50% of the GPR would have dissolved by the end of the second year after application. On the other hand, if a previously limed soil ((pH_w 5.8) contains variable-charge components, the model predicts that virtually all of the GPR would have dissolved in this soil by the end of the second year after application. These results emphasise that, even in the presence of a high proton supply, solution Ca has an overriding influence on the dissolution of GPR. The faster rate of GPR dissolution in the limed soil with variable charge, compared to that in the limed soil with permanent charge only, demonstrates the ability of the variable-charge component of soil to act as a sink for some of the lime-derived Ca. According to the solubility product principle, this allows more GPR to dissolve. Because of the generally stronger buffering of soil for P than for Ca, a relatively large proportion of any P removed by leaching and plant uptake is buffered by the sorbed phase. Consequently, the influence of leaching and plant uptake on GPR dissolution is attributed primarily to the removal of the relatively less-strongly buffered Ca.     

Formalin treatment for intractable hemorrhagic cystitis: a review of the literature with 16 additional cases

Acute, exsanguinating hemorrhagic cystitis secondary to cyclophosphamide therapy, radiation therapy, or an infiltrating bladder tumor may be managed successfully with intravesical Formalin therapy. The indications for its use, the technique, success rates, and complications are discussed. This treatment was effective in 14 of 16 patients in the present series and 79 of 90 cases reported in the literature. Dilutions of 4% or less were as effective as a 10% dilution and were associated with far fewer complications. The early use of Formalin in the treatment of intractable hemorrhagic cystitis is recommended.