Development and Usability Assessment of a Connected Resistance Exercise Band Application for Strength-Monitoring.

Resistance exercise bands are a core component of any physical activity strengthening program. Strength training can mitigate the development of sarcopenia, the loss of muscle mass or strength and function with aging. Yet, the adherence of such behavioral exercise strategies in a home-based setting are fraught with issues of monitoring and compliance. Our group developed a Bluetooth-enabled resistance exercise band capable of transmitting data to an open-source platform. In this work, we developed an application to capture this information in real-time, and conducted three usability studies in two mixed-aged groups of participants (n=6 each) and a group of older adults with obesity participating in a weight-loss intervention (n=20). The system was favorable, acceptable and provided iterative information that could assist in future deployment on ubiquitous platforms. Our formative work provides the foundation to deliver home-based monitoring interventions in a high-risk, older adult population.

An Inverse Problems Approach to MR-EPT Image Reconstruction.

Magnetic Resonance-Electrical Properties Tomography (MR-EPT) is an imaging modality that maps the spatial distribution of the electrical conductivity and permittivity using standard MRI systems. The presence of a body within the scanner alters the RF field, and by mapping these alterations it is possible to recover the electrical properties. The field is time-harmonic, and can be described by the Helmholtz equation. Approximations to this equation have been previously used to estimate conductivity and permittivity in terms of first or second derivatives of RF field data. Using these same approximations, an inverse approach to solving the MR-EPT problem is presented here that leverages a forward model for describing the magnitude and phase of the field within the imaging domain, and a fitting approach for estimating the electrical properties distribution. The advantages of this approach are that 1) differentiation of the measured data is not required, thus reducing noise sensitivity, and 2) different regularization schemes can be adopted, depending on prior knowledge of the distribution of conductivity or permittivity, leading to improved image quality. To demonstrate the developed approach, both Quadratic (QR) and Total Variation (TV) regularization methods were implemented and evaluated through numerical simulation and experimentally acquired data. The proposed inverse approach to MR-EPT reconstruction correctly identifies contrasts and accurately reconstructs the geometry in both simulations and experiments. The TV regularized scheme reconstructs sharp spatial transitions, which are difficult to reconstruct with other, more traditional approaches.

Electrical property sensing biopsy needle for prostate cancer detection.

BACKGROUND: Significant electrical property differences have been demonstrated to exist between malignant and benign prostate tissues. We evaluated how well a custom designed clinically deployable electrical property sensing biopsy needle is able to discriminate between these tissue types in an ex vivo prostate model. METHODS: An electrical impedance spectroscopy (EIS) sensing biopsy (Bx) needle was developed to record resistive (ρR) and reactive (ρX) components of electrical impedance from 100 Hz to 1 MHz. Standard twelve-core biopsy protocols were followed, in which the EIS-Bx device was used to gauge electrical properties prior to extracting tissue cores through biopsy needle firing from 36 ex vivo human prostates. Histopathological assessment of the cores was statistically compared to the impedance spectrum gauged from each core. RESULTS: The magnitudes of the mean resistive and reactive components were significantly higher in cancer tissues (P < 0.05). ROC curves showed that ρR at 63.09 kHz was optimal for discriminating cancer from benign tissues; this parameter had 75.4% specificity, 76.1% sensitivity, and ROC AUC of 0.779. Similarly, 251.1 kHz was optimal when using ρX to discriminate cancer from benign tissues; this parameter had a 77.9% specificity, 71.4% sensitivity, and ROC AUC of 0.79. CONCLUSION: Significant electrical property differences noted between benign and malignant prostate tissues suggest the potential efficacy an EIS-Bx device would provide for cancer detection in a clinical setting. By sensing a greater fraction of the prostate's volume in real-time, the EIS-Bx device has the potential to improve the accuracy of cancer grading and volume estimation made with current biopsy procedures.

Energy from Waste--clean, efficient, renewable: transitions in combustion efficiency and NOx control.

Traditionally EfW (Energy from Waste) plants apply a reciprocating grate to combust waste fuel. An integrated steam generator recovers the heat of combustion and converts it to steam for use in a steam turbine/generator set. This is followed by an array of flue gas cleaning technologies to meet regulatory limitations. Modern combustion applies a two-step method using primary air to fuel the combustion process on the grate. This generates a complex mixture of pyrolysis gases, combustion gases and unused combustion air. The post-combustion step in the first pass of the boiler above the grate is intended to "clean up" this mixture by oxidizing unburned gases with secondary air. This paper describes modifications to the combustion process to minimize exhaust gas volumes and the generation of noxious gases and thus improving the overall thermal efficiency of the EfW plant. The resulting process can be coupled with an innovative SNCR (Selective Non-Catalytic Reduction) technology to form a clean and efficient solid waste combustion system. Measurements immediately above the grate show that gas compositions along the grate vary from 10% CO, 5% H(2) and 0% O(2) to essentially unused "pure" air, in good agreement with results from a mathematical model. Introducing these diverse gas compositions to the post combustion process will overwhelm its ability to process all these gas fractions in an optimal manner. Inserting an intermediate step aimed at homogenizing the mixture above the grate has shown to significantly improve the quality of combustion, allowing for optimized process parameters. These measures also resulted in reduced formation of NO(x) (nitrogenous oxides) due to a lower oxygen level at which the combustion process was run (2.6 vol% O(2,)(wet) instead of 6.0 vol% O(2,)(wet)). This reduction establishes optimal conditions for the DyNOR™ (Dynamic NO(x) Reduction) NO(x) reduction process. This innovative SNCR technology is adapted to situations typically encountered in solid fuel combustion. DyNOR™ measures temperature in small furnace segments and delivers the reducing reagent to the exact location where it is most effective. The DyNOR™ distributor reacts precisely and dynamically to rapid changes in combustion conditions, resulting in very low NO(x) emissions from the stack.

Multi-GPU Jacobian accelerated computing for soft-field tomography.

Image reconstruction in soft-field tomography is based on an inverse problem formulation, where a forward model is fitted to the data. In medical applications, where the anatomy presents complex shapes, it is common to use finite element models (FEMs) to represent the volume of interest and solve a partial differential equation that models the physics of the system. Over the last decade, there has been a shifting interest from 2D modeling to 3D modeling, as the underlying physics of most problems are 3D. Although the increased computational power of modern computers allows working with much larger FEM models, the computational time required to reconstruct 3D images on a fine 3D FEM model can be significant, on the order of hours. For example, in electrical impedance tomography (EIT) applications using a dense 3D FEM mesh with half a million elements, a single reconstruction iteration takes approximately 15-20 min with optimized routines running on a modern multi-core PC. It is desirable to accelerate image reconstruction to enable researchers to more easily and rapidly explore data and reconstruction parameters. Furthermore, providing high-speed reconstructions is essential for some promising clinical application of EIT. For 3D problems, 70% of the computing time is spent building the Jacobian matrix, and 25% of the time in forward solving. In this work, we focus on accelerating the Jacobian computation by using single and multiple GPUs. First, we discuss an optimized implementation on a modern multi-core PC architecture and show how computing time is bounded by the CPU-to-memory bandwidth; this factor limits the rate at which data can be fetched by the CPU. Gains associated with the use of multiple CPU cores are minimal, since data operands cannot be fetched fast enough to saturate the processing power of even a single CPU core. GPUs have much faster memory bandwidths compared to CPUs and better parallelism. We are able to obtain acceleration factors of 20 times on a single NVIDIA S1070 GPU, and of 50 times on four GPUs, bringing the Jacobian computing time for a fine 3D mesh from 12 min to 14 s. We regard this as an important step toward gaining interactive reconstruction times in 3D imaging, particularly when coupled in the future with acceleration of the forward problem. While we demonstrate results for EIT, these results apply to any soft-field imaging modality where the Jacobian matrix is computed with the adjoint method.

A real-time electrical impedance sensing biopsy needle.

Diagnostic confirmation of cancer in solid organs is based on biopsy findings. In a standard 12-core prostate biopsy protocol, conventional biopsy needles sample only 0.95% (∼0.228 cm³) of a typical 24-cm³ prostate gland. The primary objective of this study was to enhance the sensitivity of standard biopsy protocol by gauging electrical properties of tissue simultaneously with tissue extraction for histopathology analysis. A conventional biopsy (Bx) needle was instrumented with an electrical impedance spectroscopy (EIS) sensor to interrogate the tissue volume surrounding the needle tip. The EIS-Bx device was evaluated in a series of saline bath and ex vivo porcine experiments. It was found to sense a volume of 0.286 cm³ of tissue around the needle tip. EIS measurements were recorded from three ex vivo human prostates using the device, and the extracted biopsy cores were histologically assessed. Prostate conductivity σ ranged from 0.179 to 0.3310 S/m for benign tissues and 0.0746 to 0.0837 S/m for malignant tissues at frequencies ranging from 1 to 100 kHz. Relative permittivity ϵ(r) ranged from 2.10×106 to 2.9 × 104 for benign and 6.63×105 to 5.3 × 10³ for cancer tissues over the same frequency range. Both are found to be significantly higher in normal prostate tissues than in malignant tissue (p < 0.00001).

Anatomically accurate hard priors for transrectal electrical impedance tomography (TREIT) of the prostate.

Current prostate biopsy procedures entail sampling tissues at template-based locations that are not patient specific. Ultrasound (US)-coupled transrectal electrical impedance tomography (TREIT), featuring an endorectal US probe retrofitted with electrodes, has been developed for prostate imaging. This multi-modal imaging system aims to identify suspicious tumor regions based on their electrical properties and ultimately provide additional patient-specific locations where to take biopsy samples. Unfortunately, the open-domain geometry associated with TREIT results in a severely ill-posed problem due to the small number of measurements and unbounded imaging domain. Furthermore, reconstructing contrasts within the prostate volume is challenging because the conductivity differences between the prostate and surrounding tissues are much larger than the conductivity differences between benign and malignant tissues within the prostate. To help overcome these problems, anatomically accurate hard priors can be employed to limit estimation of the electrical property distribution to within the prostate volume; however, this requires the availability of structural information. Here, a method that extracts the prostate surface from US images and incorporates this surface into the image reconstruction algorithm has been developed to enable estimation of electrical parameters within the prostate volume. In this paper, the performance of this algorithm is evaluated against a more traditional EIT algorithm that does not use anatomically accurate structural information, in the context of numerical simulations and phantom experiments. The developed anatomically accurate hard-prior algorithm demonstrably identifies contrasts within the prostate volume while an algorithm that does not rely on anatomically accurate structural information is unable to localize these contrasts. While inclusions are identified in the correct locations, they are found to be smaller in size than the actual object due to the rapid decay in sensitivity at increasing distances from the probe surface. Despite this, identifying the size of the inclusion accurately may not be essential for biopsy guidance in a clinical setting; instead, knowledge of the general vicinity of a cancerous lesion may be sufficient for suggesting and guiding clinicians to extract additional biopsy cores.

Electrical impedance spectroscopy for prostate cancer diagnosis.

Electrical impedance was recorded at 21 discrete frequencies (1 to 100 kHz) from 27 ex vivo human prostates. These electrical properties were measured by using custom designed Electrical Impedance Spectroscopy (EIS) sensing biopsy (Bx) needles. EIS-Bx needles gauge the electrical properties of tissue in tandem with the tissue extraction (used for histopathological assessment). The EIS-Bx probe has a signal-to-noise ratio (SNR) of 65 dB across the frequency range (1 kHz to 100 kHz). A total of 36 cancers and 288 benign regions were sampled from 27 human prostates. Mean resistance (R) of prostate decreased from 537.27 Ω to 126.74 Ω for benign tissues and 999.52 Ω to 340.67 Ω for malignant tissues across the 1 kHz - 100 kHz spectral range. Likewise, mean reactance (X) ranged from -391.41 Ω to -62.6 Ω for benign and -675.09 Ω to -162.28 Ω for cancer tissues over the same frequency range. Both R and X values are found to be significantly lower in normal prostate tissues than in malignant tissue (p<0.001). Further testing to evaluate the clinical efficacy of this coupled device is underway.

Optical breast shape capture and finite-element mesh generation for electrical impedance tomography.

X-ray mammography is the standard for breast cancer screening. The development of alternative imaging modalities is desirable because mammograms expose patients to ionizing radiation. Electrical impedance tomography (EIT) may be used to determine tissue conductivity, a property which is an indicator of cancer presence. EIT is also a low-cost imaging solution and does not involve ionizing radiation. In breast EIT, impedance measurements are made using electrodes placed on the surface of the patient's breast. The complex conductivity of the volume of the breast is estimated by a reconstruction algorithm. EIT reconstruction is a severely ill-posed inverse problem. As a result, noisy instrumentation and incorrect modelling of the electrodes and domain shape produce significant image artefacts. In this paper, we propose a method that has the potential to reduce these errors by accurately modelling the patient breast shape. A 3D hand-held optical scanner is used to acquire the breast geometry and electrode positions. We develop methods for processing the data from the scanner and producing volume meshes accurately matching the breast surface and electrode locations, which can be used for image reconstruction. We demonstrate this method for a plaster breast phantom and a human subject. Using this approach will allow patient-specific finite-element meshes to be generated which has the potential to improve the clinical value of EIT for breast cancer diagnosis.

Sensitivity study of an ultrasound coupled transrectal electrical impedance tomography system for prostate imaging.

In 2009, prostate cancer ranked as the most common cancer and the second most fatal cancer in men in the United States. Unfortunately, the current clinical diagnostic methods (e.g. prostate-specific antigen (PSA), digital rectal examination, endorectal MRI, transrectal ultrasound, biopsy) used for detecting and staging prostate cancer are limited. It has been shown that cancerous prostate tissue has significantly different electrical properties when compared to benign tissues. Based on these electrical property findings, a transrectal electrical impedance tomography (TREIT) system is proposed as a novel prostate imaging modality. The TREIT system comprises an array of electrodes interfaced with a clinical transrectal ultrasound (TRUS) probe. We evaluate this imaging system through a series of phantom imaging experiments to assess the system's ability to image high and low contrast objects at various positions. We found that the TREIT system can easily discern high contrast inclusions of 1 cm in diameter at distances centered at two times the radius of the TREIT probe away from the probe surface. Furthermore, this technology's ability to detect low contrast inclusions suggests that it has the potential to successfully detect prostate cancer.

Electrical impedance tomography reconstruction for three-dimensional imaging of the prostate.

Transrectal electrical impedance tomography (TREIT) has been proposed as an adjunct modality for enhancing standard clinical ultrasound (US) imaging of the prostate. The proposed TREIT probe has an array of electrodes adhered to the surface of a cylindrical US probe that is introduced inside of the imaging volume. Reconstructing TREIT images in the open-domain geometry established with this technique poses additional challenges to those encountered with closed-domain geometries, present in more conventional EIT systems, because of the rapidly decaying current densities at increasing distances from the probe surface. We developed a finite element method (FEM)-based dual-mesh reconstruction algorithm which employs an interpolation scheme for linking a fine forward mesh with a coarse grid of pixels, used for conductivity estimation. Simulation studies using the developed algorithm demonstrate the feasibility of imaging moderately contrasting inclusions at distances of three times the probe radius from the probe surface and at multiple angles about the probe's axis. The large, dense FEM meshes used here require significant computational effort. We have optimized our reconstruction algorithm with multi-core processing hardware and efficient parallelized computational software packages to achieve a speedup of 9.3 times when compared to a more traditional Matlab-based, single CPU solution. The simulation findings and computational optimization provide a state-of-the-art reconstruction platform for use in further evaluating transrectal electrical impedance tomography.

Sensitivity study and optimization of a 3D electric impedance tomography prostate probe.

In current clinical practice, the primary diagnostic method for testing for prostate cancer is ultrasound-guided biopsy. In this paper, we consider using a sonolucent array of electrodes, printed on a thin Kapton layer and positioned on the imaging window of a transrectal ultrasound probe, as a method for providing coregistered electrical and ultrasound imaging of the prostate. As the electrical properties of malignant tissues have been shown to differ significantly from benign tissues, the estimation of the electrical properties is expected to be helpful in distinguishing certain beginning pathologies from cancer and in improving the detection rate that current biopsy methods provide. One of the main difficulties in estimating electrical properties of tissues with this electrode configuration is the rapid decay of the sensitivity with distance from the sensing array. In order to partially overcome this difficulty, we propose to use prior information from the ultrasound (US). Specifically we intend to delineate the boundaries of the prostate from the US, to subdivide the organ into a small number of voxels and to estimate the conductivity as constant on each of these subvolumes. We use a 3D forward model based on the finite element method for studying the sensitivity of a simulated segmented prostate for three different electrode array designs. The three designs present different electrode areas and inter-electrode gaps. Larger electrodes are desirable as they present a better contact, but we show that as they result in smaller inter-electrode gaps, shunting currents can be significant and the sensitivity is reduced. Because our clinical measurement system employs a single current source, we consider tetrapolar measurement patterns for evaluating these electrode configurations. Optimal measurement patterns are well defined for adaptive systems, where multiple currents are injected at the same time. For the electrode array designs we consider, which are three dimensional, there are no established systematic methods for forming sets of linearly independent tetrapolar measurement patterns. We develop a novel method for automatically computing a full set of independent tetrapolar measurement patterns that maximizes the sensitivity in a region of interest (ROI). We use these patterns in the forward modeling and sensitivity studies. In addition to the electrode arrays on the probe, we study the use of a further configuration, where a distal electrode is positioned on the exterior of the body and used for current injection.

Imaging forearm blood flow with pulse-ox gated electrical impedance tomography.

Assessing peripheral vasculature health has the potential to impact clinical decision making in terms of treating patients with cardiovascular disease. The electrical conductivity of certain tissue regions within the forearm change as blood vessels undergo pulsatile dilation in synchrony with the beating of the heart. We use dynamic electrical impedance tomography (EIT) gated to the peak of a pulse oxymetry plethysmography waveform to image this temporally varying spatial conductivity. A phantom imaging experiment is presented showing that small conductivity changes of less than 1 mm are detectable using the developed dynamic EIT system. This system is used to image a volunteer's forearm during resting cardiovascular activity. Similar structures are observed in the plethysmography trace and the temporally varying conductivity. Spectral analysis shows that the maximum amplitude is occurring at frequencies of 1.19 Hz and 1.21 Hz for the plethysmography trace and conductivity trace, respectively. This preliminary data suggests that EIT may be sensitive enough to visualize cardiac-based pulsatility in the peripheral vessels of the forearm.

Increased susceptibility to the tobacco carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone in transgenic mice overexpressing c-myc and epidermal growth factor in alveolar type II cells.

PURPOSE: As previously described, SPC/myc transgenic mice developed bronchioloalveolar adenocarcinomas derived from alveolar type II (AT II) cells within 10-14 months, whereas SPC/IgEGF transgenic mice developed hyperplasias. Our purpose was to determine the potential interplay of environmental and genetic factors in lung tumorigenesis. MATERIALS AND METHODS: Six-week-old SPC/myc and SPC/IgEGF transgenic mice, overexpressing c-myc and a secretable form of the epidermal growth factor (IgEGF) under the control of the surfactant protein C (SPC) promoter, were treated with a single dose of the tobacco carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK). As control groups, SPC/myc and SPC/IgEGF transgenic mice were treated with NaCl and non-transgenic littermates were treated with NNK or NaCl, respectively. RESULTS: After 6 months, none of the NaCl-treated transgenic littermates showed bronchioloalveolar hyperplasia and adenocarcinoma formation, whereas 100% of the NNK-treated SPC/myc transgenic mice did. The effect of NNK on SPC/IgEGF transgenic mice was less pronounced, inducing hyperplasia in the lung in only 16.7% of them. In 90% of the NNK-treated non-transgenic littermates no neoplastic changes were detected in the lung. CONCLUSIONS: These results demonstrate that the progression of pulmonary bronchioloalveolar adenocarcinomas, induced by expression of c-myc as a transgene, was accelerated by NNK, suggesting that c-myc cooperates with NNK-induced mutations.

Expression of active human blood clotting factor VIII in mammary gland of transgenic rabbits.

Human clotting factor VIII is probably the largest protein to be expressed to date in the mammary gland of a transgenic animal, and it requires extensive posttranslational modification to achieve full biological activity. The mammary gland specific construct mWAP-hFVIII-MT-I was injected into the pronuclei of rabbit zygotes, and three transgenic offspring were obtained. Founder 385 showed germ-line transmission of a single integrated copy, and a homozygous line was established from this animal. The rhFVIII was transcribed and translated exclusively in the mammary gland. The activity of rhFVIII in the rabbit milk ranged from 5 to 8% of that found in normal human plasma. Results indicate the suitability of the transgenic rabbit mammary gland for rhFVIII production.

Application of cDNA arrays to monitor mRNA profiles in single preimplantation mouse embryos.

Array technology is a widely used tool for gene expression profiling in various biological systems. However, the application of this method to mammalian preimplantation embryos is limited by the small amount of mRNA that can be extracted from a single embryo, which is not sufficient for array analysis. Here we report a protocolfor the rapid global amplification of embryonic mRNA that permits the generation of expression profiles from single murine blastocysts. The approach combines global PCR and 77 RNA polymerase amplification and allows the preparation of labeled, amplified RNA for array hybridization from single murine blastocysts containing approximately 1.5 pg mRNA in less than 12 h. We demonstrate that this amplification procedure is highly reproducible and does not bias original relative mRNA levels. Signal patterns from various embryonic stages of murine development revealed marked differences in mRNA expression that were in accordance with previously published data. We found genes known to be involved in embryonic apoptosis expressed at different levels in individual murine day 3.5 blastocysts. This technique can thus be used to assess embryonic viability and investigate molecular mechanisms of embryonic development.

Microwave spectra and molecular structures of (Z)-pent-2-en-4-ynenitrile and maleonitrile.

Accurate equilibrium structures have been determined for (Z)-pent-2-en-4-ynenitrile (8) and maleonitrile (9) by combining microwave spectroscopy data and ab initio quantum chemistry calculations. The microwave spectra of 10 isotopomers of 8 and 5 isotopomers of 9 were obtained using a pulsed nozzle Fourier transform microwave spectrometer. The ground-state rotational constants were adjusted for vibration-rotation interaction effects calculated from force fields obtained from ab initio calculations. The resultant equilibrium rotational constants were used to determine structures that are in very good agreement with those obtained from high-level ab initio calculations (CCSD(T)/cc-pVTZ). The geometric parameters in 8 and 9 are very similar; they also do not differ significantly from the all-carbon analogue, (Z)-hex-3-ene-1,5-diyne (7), the parent molecule for the Bergman cyclization. A small deviation from linearity about the alkyne and cyano linkages is observed for 7-9 and several related species where accurate equilibrium parameters are available. The data on 7-9 should be of interest to radioastronomy and may provide insights on the formation and interstellar chemistry of unsaturated species such as the cyanopolyynes.

M-CSF transgenic mice: role of M-CSF in infection and autoimmunity.

In this study, transgenic CD2F1 mouse lines (C-1.1-C-1.11) bearing a transgene encoding the murine growth factor M-CSF under the control of the liver specific alpha-1-antitrypsin gene promoter were generated. Transgenic C-1.4 mice showed elevated expression of transgene-encoded M-CSF in the liver and displayed a 2-3-fold increase of M-CSF plasma levels and of macrophage numbers in the liver as compared with non-transgenic littermates. M-CSF transgenic mice showed increased resistance against sublethal i.v. infections with Listeria monocytogenes as compared with infected non-transgenic mice. To investigate the influence of M-CSF in murine systemic lupus erythematosus (SLE), the M-CSF transgenic mouse line C-1.4 was bred into the genetic background of SLE-prone MRL+/+ mice. The resulting C-1.4/MRL transgenic mice bearing increased endogenous M-CSF levels showed consistently lower levels of anti-ss-DNA autoantibodies as compared with non-transgenic MRL+/+ mice. The life span of the C- 1.4/MRL transgenic mice and the severity of the disease in these mice remained unchanged as compared with their non-transgenic littermates. It is concluded that in addition to M-CSF further factors must be involved in the acceleration of the autoimmune disease in SLE prone MRL/lpr mice.

Growth and development in term infants fed long-chain polyunsaturated fatty acids: a double-masked, randomized, parallel, prospective, multivariate study.

OBJECTIVE: To evaluate the effects of dietary intake of the long-chain polyunsaturated fatty acids, arachidonic acid (AA), and docosahexaenoic acid (DHA) on multiple indices of infant growth and development. DESIGN: A double-masked, randomized, parallel trial was conducted with term infants fed formulas with or without AA+DHA for 1 year (N = 239). Reference groups of breastfed infants (N = 165) weaned to formulas with and without AA+DHA were also studied. Infants in the formula groups were randomized at