A Novel Computational Approach for Simultaneous Tracking and Feature Extraction of C. elegans Populations in Fluid Environments

The nematode Caenorhabditis elegans (C. elegans) is a genetic model widely used to dissect conserved basic biological mechanisms of development and nervous system function. C. elegans locomotion is under complex neuronal regulation and is impacted by genetic and environmental factors; thus, its analysis is expected to shed light on how genetic, environmental, and pathophysiological processes control behavior. To date, computer-based approaches have been used for analysis of C. elegans locomotion; however, none of these is both high resolution and high throughput. We used computer vision methods to develop a novel automated approach for analyzing the C. elegans locomotion. Our method provides information on the position, trajectory, and body shape during locomotion and is designed to efficiently track multiple animals (C. elegans) in cluttered images and under lighting variations. We used this method to describe in detail C. elegans movement in liquid for the first time and to analyze six unc-8, one mec-4, and one odr-1 mutants. We report features of nematode swimming not previously noted and show that our method detects differences in the swimming profile of mutants that appear at first glance similar.     

Finite-Element Analysis of Ex Vivo and In Vivo Hepatic Cryoablation

Cryoablation is a widely used method for the treatment of nonresectable primary and metastatic liver tumors. A model that can accurately predict the size of a cryolesion may allow more effective treatment of tumor, while sparing normal liver tissue. We generated a computer model of tissue cryoablation using the finite-element method (FEM). In our model, we considered the heat transfer mechanism inside the cryoprobe and also cryoprobe surfaces so our model could incorporate the effect of heat transfer along the cryoprobe from the environment at room temperature. The modeling of the phase shift from liquid to solid was a key factor in the accurate development of this model. The model was verified initially in an ex vivo liver model. Temperature history at three locations around one cryoprobe and between two cryoprobes was measured. The comparison between the ex vivo result and the FEM modeling result at each location showed a good match, where the maximum difference was within the error range acquired in the experiment (< 5 degC). The FEM model prediction of the lesion size was within 0.7 mm of experimental results. We then validated our FEM in an in vivo experimental porcine model. We considered blood perfusion in conjunction with blood viscosity depending on temperature. The in vivo iceball size was smaller than the ex vivo iceball size due to blood perfusion as predicted in our model. The FEM results predicted this size within 0.1-mm error. The FEM model we report can accurately predict the extent of cryoablation in the liver.     

In-Vitro and In-Vivo Trans-Scalp Evaluation of an Intracranial Pressure Implant at 2.4 GHz

Elevation of intracranial pressure is one of the most important issues in neurosurgery and neurology in clinical practice. The prevalent techniques for measuring intracranial pressure require equipments that are wired, restricted to a hospital environment, and cause patient discomfort. A novel method for measuring the intracranial pressure is described. A wireless completely implantable device, operating at an industrial-scientific-medical band of 2.4 GHz, has been developed and tested. In-vitro and in-vivo evaluations are described to demonstrate the feasibility of microwave pressure monitoring through scalp, device integrity over a long period of time, and repeatability of pressure measurements. A distinction between an epidural and sub-dural pressure monitoring techniques is also described. Histo-pathological results obtained upon a long-term device implantation favor the utilization of the sub-dural pressure monitoring method. On the other hand, in-vivo studies illustrate a maximum pressure reading error of 0.8 mm middot Hg obtained for a sub-dural device with a capacitive microelectromechanical system sensor compared to 2 mm middot Hg obtained for an epidural device with a piezoresistive sensor.     

An In Vitro Model of a Retinal Prosthesis

Epiretinal prostheses are being developed to bypass a degenerated photoreceptor layer and excite surviving ganglion and inner retinal cells. We used custom microfabricated multielectrode arrays with 200-mum-diameter stimulating electrodes and 10-mum-diameter recording electrodes to stimulate and record neural responses in isolated tiger salamander retina. Pharmacological agents were used to isolate direct excitation of ganglion cells from excitation of other inner retinal cells. Strength-duration data suggest that, if amplitude will be used for the coding of brightness or gray level in retinal prostheses, shorter pulses (200 mus) will allow for a smaller region in the area of the electrode to be excited over a larger dynamic range compared with longer pulses (1 ms). Both electrophysiological results and electrostatic finite-element modeling show that electrode-electrode interactions can lead to increased thresholds for sites half way between simultaneously stimulated electrodes (29.4 plusmn 6.6 nC) compared with monopolar stimulation (13.3 plusmn 1.7 nC, < 0.02). Presynaptic stimulation of the same ganglion cell with both 200- and 10- m-diameter electrodes yielded threshold charge densities of 12 plusmn 6 and 7.66 plusmn 1.30 nC/cm², respectively, while the required charge was 12.5 plusmn 6.2 and 19 plusmn 3.3 nC.     

A High-Throughput Maximum a Posteriori Probability Detector

This paper presents a maximum a posteriori probability (MAP) detector, based on a forward-only algorithm that can achieve high throughputs. The MAP algorithm is optimal in terms of bit error rate (BER) performance and, with Turbo processing, can approach performance close to the channel capacity limit. The implementation benefits from optimizations performed at both algorithm and circuit level. The proposed detector utilizes a deep-pipelined architecture implemented in skew-tolerant domino and experimentally measured results verify the detector can achieve throughputs greater than 750 Mb/s while consuming 2.4 W. The 16-state EEPR4 channel detector is implemented in a 0.13$ mu{hbox {m}}$ CMOS technology and has a core area of 7.1 ${hbox {mm}}^{2}$.      

Digital Wireless—Regulation and Control Free?

Considers how different our present state of technological prowess would be if wireless systems had not been discovered and implemented, then forecasts where we are headed in the real world and what the role of government and regulators may be.     

Adaptive Impedance-Matching Techniques for Controlling L Networks

The link quality of mobile phones suffers from antenna mismatch due to fluctuating body effects. Techniques for adaptive control of impedance-matching L networks are presented, which provide automatic compensation of antenna mismatch. To secure reliable convergence, a cascade of two control loops is proposed for independent control of the real and imaginary parts of impedance. A secondary feedback path is used to enforce operation into a stable region when needed. These techniques exploit the basic properties of tunable series and parallel LC networks. A generic quadrature detector that offers a power-independent orthogonal reading of the complex impedance value is presented, which is used for direct control of variable capacitors. This approach renders calibration and elaborate software computation superfluous and allows for autonomous operation of adaptive antenna-matching modules.      

Research Progress on C-band Broadband Multibeam Klystron

Several types of C-band broadband multibeam klystrons (MBKs) are under development at the Institute of Electronics, Chinese Academy of Sciences. These MBKs operate at various C-band frequencies and have peak powers of 30-200 kW, average powers of 2-10 kW, and bandwidths of 4%-7%. The design considerations for obtaining high power and wide instantaneous bandwidths and test results for these MBKs are presented in this paper. The main technical problems, including a power sag in the band, high voltage breakdown, and non-operating mode oscillation, are also discussed. Further research work for improving the performance of these MBKs is described     

Nonlinear Influence of T-Channels in an in silico Relay Neuron

Thalamic relay cells express distinctive response modes based on the state of a low-threshold calcium channel (T-channel). When the channel is fully active (burst mode), the cell responds to inputs with a high-frequency burst of spikes; with the channel inactive ( tonic mode), the cell responds at a rate proportional to the input. Due to the T-channel's dynamics, we expect the cell's response to become more nonlinear as the channel becomes more active. To test this hypothesis, we study the response of an in silico relay cell to Poisson spike trains. We first validate our model cell by comparing its responses with in vitro responses. To characterize the model cell's nonlinearity, we calculate Poisson kernels, an approach akin to white noise analysis but using the randomness of Poisson input spikes instead of Gaussian white noise. We find that a relay cell with active T-channels requires at least a third-order system to achieve a characterization as good as a second-order system for a relay cell without T-channels.      

Theoretical Analysis of Novel Multi-Order LC Oscillators

A conventional differential pair LC oscillator is capable of generating only a single fundamental oscillation frequency. This brief presents the theoretical study of a novel oscillator that incorporates higher order LC filters to produce multiple oscillation frequencies that may be several octaves apart. These multiple oscillation frequencies are obtained from a single oscillator, thereby reducing the area of the circuit when being used for multistandard wireless applications. Moreover, a multi-order oscillator does not suffer from large parasitic capacitances from switches, which is a common drawback in switched-inductor tuned oscillators. A detailed analysis is carried out, and useful design insights are provided     

Miniature in vivo Robots for Remote and Harsh Environments

Long-term human space exploration will require contingencies for emergency medical procedures including some capability to perform surgery. The ability to perform minimally invasive surgery (MIS) would be an important capability. The use of small incisions reduces surgical risk, but also eliminates the ability of the surgeon to view and touch the surgical environment directly. Robotic surgery, or telerobotic surgery, may provide emergency surgical care in remote or harsh environments such as space flight, or extremely forward environments such as battlefields. However, because current surgical robots are large and require extensive support personnel, their implementation has remained limited in forward environments, and they would be difficult, or impossible, to use in space flight or on battlefields. This paper presents experimental analysis of miniature fixed-base and mobile in vivo robots to support MIS surgery in remote and harsh environments. The objective is to develop wireless imaging and task-assisting robots that can be placed inside the abdominal cavity during surgery. Such robots will provide surgical task assistance and enable an on-site or remote surgeon to view the surgical environment from multiple angles. This approach is applicable to long-duration space flight, battlefield situations, and for traditional medical centers and other remote surgical locations.     

On Simple Methods for Shape Reconstruction of Unknown Scatterers

Efficient and reliable reconstruction of location and shape of dielectric targets via microwave imaging is relevant in many applications. In this respect, the linear sampling method is an effective candidate to pursue this task. However, despite its simplicity and computational effectiveness, still its use is restricted to the mathematical community wherein it has been originally developed. Starting from this observation, in this paper we propose and test a simple and original "physical" interpretation of the linear sampling methods, which shows its relationship with electromagnetic focusing problems. Taking advantage of this result we discuss merits and limitations of the method and suggest new guidelines for a successful application. The analysis is supported with results against experimental data     

A Wide-Band CMOS LC VCO With Linearized Coarse Tuning Characteristics

A pseudo-exponential capacitor bank structure is proposed to implement a wide-band CMOS LC voltage-controlled oscillator (VCO) with linearized coarse tuning characteristics. An octave bandwidth VCO employing the proposed 6-bit pseudo-exponential capacitor bank structure has been realized in 0.18-mum CMOS. Compared to a conventional VCO employing a binary weighted capacitor bank, the proposed VCO has considerably reduced the variations of the VCO gain (K _VCO) and the frequency step per a capacitor bank code (f _step/code) by 2.7 and 2.1 times, respectively, across the tuning range of 924-1850 MHz. Measurement results have also shown that the VCO provides the phase noise of - 127.1 dBc/Hz at 1-MHz offset for 1.752-GHz output frequency while dissipating 6 mA from a 1.8-V supply.     

Systematic Design of Supply Regulated LC-Tank Voltage-Controlled Oscillators

Systematic design of low-dropout-regulator (LDO) regulated low-phase-noise LC-tank voltage controlled oscillators (VCOs) is presented. Low-frequency sensitivity profile of power supply induced phase noise of a typical cross-coupled LC-tank VCO is investigated. The relationship between frequency pushing and power supply-induced phase noise is derived. Systematic codesign of VCO sensitivity to low-frequency supply noise with respect to an LDO output noise and power supply rejection profile is introduced. To demonstrate the design approach experimentally, two 2.4-GHz LC-tank VCOs with pMOS and nMOS switching devices powered by PFET LDOs are designed and fabricated on an 0.18-$mu$m, 7-layer metal CMOS process. By using an integrated LDO, it is shown that the VCO phase-noise sensitivity to low frequency improves by 55 dB at 100-kHz offset.      

Dual-Band LC VCO Architecture With a Fourth-Order Resonator

A dual-band LC voltage-controlled oscillator (VCO) architecture suitable for GSM/PCS/DCS applications is presented. The VCO utilizes a fourth-order resonance tank and avoids quality-factor-deteriorating switches. The paper outlines the design tradeoffs and the VCO when using a fourth-order resonator. The 0.8-GHz/1.8-GHz test chip was fabricated in the 0.5-mum IBM-5AM SiGe process and has achieved phase noise of -134 dBc/Hz at a 1-MHz frequency offset from the carrier, with 56-MHz and 121-MHz tuning ranges in the corresponding bands. The VCO core consumes 15 mW from a 2.5-V power supply     

In Vivo Impedance Imaging With Total Variation Regularization

We show that electrical impedance tomography (EIT) image reconstruction algorithms with regularization based on the total variation (TV) functional are suitable for in vivo imaging of physiological data. This reconstruction approach helps to preserve discontinuities in reconstructed profiles, such as step changes in electrical properties at interorgan boundaries, which are typically smoothed by traditional reconstruction algorithms. The use of the TV functional for regularization leads to the minimization of a nondifferentiable objective function in the inverse formulation. This cannot be efficiently solved with traditional optimization techniques such as the Newton method. We explore two implementations methods for regularization with the TV functional: the lagged diffusivity method and the primal dual–interior point method (PD-IPM). First we clarify the implementation details of these algorithms for EIT reconstruction. Next, we analyze the performance of these algorithms on noisy simulated data. Finally, we show reconstructed EIT images of in vivo data for ventilation and gastric emptying studies. In comparison to traditional quadratic regularization, TV regulariza tion shows improved ability to reconstruct sharp contrasts.      

High-Program/Erase-Speed SONOS With In Situ Silicon Nanocrystals

In this letter, for the first time, we have successfully fabricated silicon-oxide-nitride-oxide-silicon (SONOS) devices with embedded silicon nanocrystals (Si-NCs) in silicon nitride using in situ method. This process is simple and compatible to modern IC processes. Different Si-NCs deposition times by in situ method were investigated at first. SONOS devices with embedded Si-NCs in silicon nitride exhibit excellent characteristics in terms of larger memory windows (> 5.5 V), lower operation voltage, high P/E speed, and longer retention time (> 10⁸ s for 13% charge loss).     

A Novel Driving Scheme for Synchronous Rectifiers in LLC Resonant Converters

This paper proposes a novel synchronous rectifier (SR) driving scheme for resonant converters. It is very suitable for high-frequency, high-efficiency, and high-power-density dc–dc resonant converters with SRs. In this paper, an LLC resonant converter with the proposed synchronous rectification is designed and analyzed. With the proposed driving scheme, the SR body diode conduction is reduced to almost zero. The driving scheme eliminates the reverse-recovery problem of SRs. Both current and voltage stresses are greatly decreased, and the conduction loss and switching loss of SRs are also reduced considerably. The experimental results show that the proposed LLC resonant converter with SRs can achieve low stress, high efficiency, and high power density.      

An Accurate Automatic Quality-Factor Tuning Scheme for Second-Order LC Filters

This paper presents a scheme to accurately tune the quality factor of second-order LC bandpass filters. The information of the magnitude response at the center and one of the cutoff frequencies is used to tune both the amplitude and the quality factor of the filter using two independent yet interacting loops. Furthermore, the synergic interaction between the loops makes the proposed scheme stable and insensitive to the mismatch between the input amplitudes. A chip prototype was implemented in a 0.35-mum CMOS process and consumes 4.3 mA from a single 1.3-V supply. Measurement results show that at 1.97 GHz the quality factor is tunable from 60 to 220 while the amplitude is tunable between -15 and 0 dBm with worst case quality factor and amplitude tuning accuracies of 10% and 7%, respectively     

In Situ Acoustic Temperature Measurement During Variable-Frequency Microwave Curing

Variable-frequency microwave (VFM) curing can perform the same processing steps as conventional thermal processing in minutes, without compromising intrinsic material properties. With increasing demand for novel dielectrics, there is a corresponding demand for new processing techniques that lead to comparable or better properties than conventional methods. VFM processing can be a viable alternative to conventional thermal techniques. However, current limitations include a lack of reliable temperature measuring techniques. This research focuses on developing a reliable temperature measuring system using acoustic techniques to monitor low-k polymer dielectrics cured on silicon wafers in a VFM furnace. The acoustic sensor exhibits the capability to measure temperatures from 20degC to 300degC with an attainable accuracy of plusmn2 degrees.