LabVIEW Interface Research Articles

SU-E-T-112: Experimental Characterization of a Novel Thermal Reservoir for Consistent and Accurate Annealing of High-Sensitivity TLDs.

To develop and characterize a novel thermal reservoir for consistent and accurate annealing of high-sensitivity thermoluminescence dosimeters (TLD-100H) for dosimetry of brachytherapy sources. The sensitivity of TLD-100H is about 18 times that of TLD-100 which has clear advantages in for interstitial brachytherapy sources. However, the TLD-100H requires a short high temperature annealing cycle (15 min.) and opening and closing the oven door causes significant temperature fluctuations leading to unreliable measurements. A new thermal reservoir made of aluminum alloy was developed to provide stable temperature environment in a standard hot air oven. The thermal reservoir consisted of a 20 cm × 20 cm × 8 cm Al block with a machine-milled chamber in the middle to house the aluminum TLD holding tray. The thermal reservoir was placed inside the oven until it reaches thermal equilibrium with oven chamber. The temperatures of the oven chamber, heat reservoir, and TLD holding tray were monitored by two independent thermo-couples which interfaced digitally to a control computer. A LabView interface was written for monitoring and recording the temperatures in TLD holding tray, the thermal reservoir, and oven chamber. The temperature profiles were measured as a function of oven-door open duration. The settings for oven chamber temperature and oven door open-close duration were optimized to achieve a stable temperature of 240 0C in the TLD holding tray. Complete temperature profiles of the TLD annealing tray over the entire annealing process were obtained. A LabView interface was written for monitoring and recording the temperatures in TLD holding The use of the thermal reservoir has significantly reduced the temperature fluctuations caused by the opening of oven door when inserting the TLD holding tray into the oven chamber. It has enabled consistent annealing of high-sensitivity TLDs. A comprehensive characterization of a custom-built novel thermal reservoir for annealing high-sensitivity TLD has been carried out. It enabled consistent and accurate annealing of high- sensitivity TLDs which could significantly improve the efficiency of brachytherapy source characterizations. Supported in part by NIH grant R01-CA134627.

A RECONFIGURABLE ULTRAWIDEBAND (UWB) COMPACT TREE-DESIGN ANTENNA SYSTEM

A novel compact tree-design antenna (NCTA) with the ability of reconflgurable ultra-wideband (UWB) of 3.1GHz to 10.6GHz to flve multi-narrowband applications is proposed. This antenna has a novel radiating element design that consists of seven small circles (7- fllter) surrounding a central circle. Moreover, the NCTA incorporates the 7-fllter that functioned as fllter into the antenna design. The compact 38mm£38mm antenna integrates three PIN diode switches, which are connected to a single National Instrument Data Acquisition (NI-DAQ) Board. The DAQ itself is controlled (ON/OFF state) by a virtual instrument known as \Lab VIEW Interface Software. The activation of speciflc PIN diode switches in the conflguration that is controlled by the DAQ then, in turn, determines the frequency agility. The presented antenna is capable of performing up to flve multibands. The operating frequencies are as follows; band 1 (2.72{ 11.8GHz), band 2 (2.4{4GHz, 5.3{11.6GHz), band 3 (2.7{6.5GHz, 7.1{11.6GHz), band 4 (2.7{4.4GHz, 5.2{6.5GHz, 7.1{11.7GHz) and band 5 (2.6{3.5GHz, 4.8{7.0GHz, 7.4GHz{11.5GHz). Furthermore, the antenna has a gain of up to 6dBi which is considered better than that of conventional antenna. The proposed antenna produces a proflcient divisive radiation pattern at 4 and 6GHz. The experimental

A programmable microfluidic cell array for combinatorial drug screening.

We describe the development of a fully automatic and programmable microfluidic cell culture array that integrates on-chip generation of drug concentrations and pair-wise combinations with parallel culture of cells for drug candidate screening applications. The device has 64 individually addressable cell culture chambers in which cells can be cultured and exposed either sequentially or simultaneously to 64 pair-wise concentration combinations of two drugs. For sequential exposure, a simple microfluidic diffusive mixer is used to generate different concentrations of drugs from two inputs. For generation of 64 pair-wise combinations from two drug inputs, a novel time dependent variable concentration scheme is used in conjunction with the simple diffusive mixer to generate the desired combinations without the need for complex multi-layer structures or continuous medium perfusion. The generation of drug combinations and exposure to specific cell culture chambers are controlled using a LabVIEW interface capable of automatically running a multi-day drug screening experiment. Our cell array does not require continuous perfusion for keeping cells exposed to concentration gradients, minimizing the amount of drug used per experiment, and cells cultured in the chamber are not exposed to significant shear stress continuously. The utility of this platform is demonstrated for inducing loss of viability of PC3 prostate cancer cells using combinations of either doxorubicin or mitoxantrone with TRAIL (TNF-alpha Related Apoptosis Inducing Ligand) either in a sequential or simultaneous format. Our results demonstrate that the device can capture the synergy between different sensitizer drugs and TRAIL and demonstrate the potential of the microfluidic cell array for screening and optimizing combinatorial drug treatments for cancer therapy.

Urocortins Improve Dystrophic Skeletal Muscle Structure and Function through Both PKA- and Epac-Dependent Pathways

In Duchenne muscular dystrophy, the absence of dystrophin causes progressive muscle wasting and premature death. Excessive calcium influx is thought to initiate the pathogenic cascade, resulting in muscle cell death. Urocortins (Ucns) have protected muscle in several experimental paradigms. Herein, we demonstrate that daily s.c. injections of either Ucn 1 or Ucn 2 to 3-week-old dystrophic mdx(5Cv) mice for 2 weeks increased skeletal muscle mass and normalized plasma creatine kinase activity. Histological examination showed that Ucns remarkably reduced necrosis in the diaphragm and slow- and fast-twitch muscles. Ucns improved muscle resistance to mechanical stress provoked by repetitive tetanizations. Ucn 2 treatment resulted in faster kinetics of contraction and relaxation and a rightward shift of the force-frequency curve, suggesting improved calcium homeostasis. Ucn 2 decreased calcium influx into freshly isolated dystrophic muscles. Pharmacological manipulation demonstrated that the mechanism involved the corticotropin-releasing factor type 2 receptor, cAMP elevation, and activation of both protein kinase A and the cAMP-binding protein Epac. Moreover, both STIM1, the calcium sensor that initiates the assembly of store-operated channels, and the calcium-independent phospholipase A(2) that activates these channels were reduced in dystrophic muscle by Ucn 2. Altogether, our results demonstrate the high potency of Ucns for improving dystrophic muscle structure and function, suggesting that these peptides may be considered for treatment of Duchenne muscular dystrophy.

An Automated Antenna Measurement System Utilizing Wi-Fi Hardware

We propose a system that measures three-dimensional gain patterns of an unknown antenna using the received signal-strength indicator (RSSI) provided by Wi-Fi hardware. Our system uses widely available Wi-Fi routers to generate the RF signal and to measure incident power. A simple two-axis positioner allows the full three-dimensional pattern of the antenna to be measured, and a LabVIEW interface lets users control measurements and view results. We make use of inexpensive, readily available materials and rudimentary construction techniques.

Detection of microdroplet size and speed using capacitive sensors

Detection of the presence, size and speed of microdroplets in microfluidic devices is presented using commercially available capacitive sensors which make the droplet based microfluidic systems scalable and inexpensive. Cross-contamination between the droplets is eliminated by introducing a passivation layer between the sensing electrodes and droplets. A simple T-junction generator is used to generate droplets in microchannels. Coplanar electrodes are used to form a capacitance through the microfluidic channel. The change in capacitance due to the presence of a droplet in the sensing area is detected and used to determine the size and speed of the droplet. The design of a single pair of electrodes is used to detect the presence of a droplet and the interdigital finger design is used to detect the size and speed of the droplet. An analytical model is developed to predict the detection signal and guide the experimental optimization of the sensor geometry. The measured droplet information is displayed through a Labview interface in real-time. The use of capacitance sensors to monitor droplet sorting at a T-junction is also presented. The discussions in this paper can be generalized to any droplet detection application and can serve as a guideline in sensor selection.

High-Throughput Single Molecule Measurements Confirm a Load-Dependent Association Rate for E-Selectin and Sialyl Lewisa

We previously reported the association rate between E-selectin and sialyl Lewisa, two molecules involved in leukocyte adhesion and rolling, to be accelerated by compressive loads acting between them (Snook and Guilford, 2010). To improve and expand these studies, we have built a magnetic bond pulling system for high-throughput data collection from single molecules for studies of load-dependent kinetics. The system allows us to replicate laser trap and biomembrane force probe experiments on a larger scale. Four electromagnets are arranged in a tetrahedron, two above and two below a flow cell. These provide uniform upward and downward forces, respectively. The system is controlled through a LabVIEW interface and is capable of producing vertical pushing and pulling forces up to ∼40 pN between receptor-coated surfaces and 3 μm ligand-coated superparamagnetic beads. Loads are applied to dozens of beads simultaneously, which are tracked through video microscopy with a temporal resolution of 11 ms. We used the device to investigate the possibility of a load-dependent rate of association between E-selectin and sialyl Lewisa. The fraction of contacts forming a bond (“adhesion probability”) can be fitted as a function of contact time to determine the 2-dimensional on-rate. This was done over a range of compressive forces to determine the effect of compressive force on 2D on-rate. We confirmed that compressive force does indeed increase the rate of association between E-selectin and sialyl Lewisa. This high-throughput approach will allow us to more rapidly investigate the origin of this phenomenon.

智能公交车载下位机与调度监控中心上位机功能设计

Advanced public transportation system(ATPS) traffic information interaction is based on function design of the main modules. In this paper, functions of ATPS car terminal and control center PC are designed. The design of car terminal includes the wireless communication module, passenger traffic volume detection module, key input module and screen display module. The design of control center PC includes LabVIEW communication module and interface of control center. The design makes the information be interacted between car terminal and control center PC, sends information about the driving buses to the bus stop, and makes the control center manage buses scientifically.

Dual-mode Imaging of Cutaneous Tissue Oxygenation and Vascular Function

Accurate assessment of cutaneous tissue oxygenation and vascular function is important for appropriate detection, staging, and treatment of many health disorders such as chronic wounds. We report the development of a dual-mode imaging system for non-invasive and non-contact imaging of cutaneous tissue oxygenation and vascular function. The imaging system integrated an infrared camera, a CCD camera, a liquid crystal tunable filter and a high intensity fiber light source. A Labview interface was programmed for equipment control, synchronization, image acquisition, processing, and visualization. Multispectral images captured by the CCD camera were used to reconstruct the tissue oxygenation map. Dynamic thermographic images captured by the infrared camera were used to reconstruct the vascular function map. Cutaneous tissue oxygenation and vascular function images were co-registered through fiduciary markers. The performance characteristics of the dual-mode image system were tested in humans.

Dual-mode Imaging of Cutaneous Tissue Oxygenation and Vascular Function

Accurate assessment of cutaneous tissue oxygenation and vascular function is important for appropriate detection, staging, and treatment of many health disorders such as chronic wounds. We report the development of a dual-mode imaging system for non-invasive and non-contact imaging of cutaneous tissue oxygenation and vascular function. The imaging system integrated an infrared camera, a CCD camera, a liquid crystal tunable filter and a high intensity fiber light source. A Labview interface was programmed for equipment control, synchronization, image acquisition, processing, and visualization. Multispectral images captured by the CCD camera were used to reconstruct the tissue oxygenation map. Dynamic thermographic images captured by the infrared camera were used to reconstruct the vascular function map. Cutaneous tissue oxygenation and vascular function images were co-registered through fiduciary markers. The performance characteristics of the dual-mode image system were tested in humans.

330 GHz FMCW Image Sensor for Homeland Security Applications

A single-pixel imaging remote sensor operating at 330 GHz is described. It is based on a frequency modulated continuous wave (FMCW) and aimed at detection of concealed objects for ranges up to 40 m. The system consists of 2 horn-lens antennas integrated with a homodyne transceiver. The synthesized linear FMCW signal at X-band is multiplied by a factor of 32 to generate the transmitted signal. An intermediate frequency (IF) signal obtained in the output port of the 2-nd harmonic mixer is employed for image processing. Distance measurements were made by performing data acquisition unit based on LabView interface and resulting in a range resolution about 1 cm. Examples of 2D and 3D images reconstructed with this sensor are presented.

A Pilot Study of Respiratory Inductance Plethysmography as a Safe, Noninvasive Detector of Jet Ventilation Under General Anesthesia

High-frequency jet ventilation is an optimal mode of ventilation for many surgical procedures of the trachea and larynx but has limited monitoring modalities to assess adequacy of oxygenation and/or ventilation. Respiratory inductance plethysmography is a noninvasive monitor of chest and abdominal wall movement with well-established applications in the sleep laboratory. We performed an observational pilot study of respiratory inductance plethysmography as a detector of jet ventilation. Twenty-five patients underwent microdirect suspension laryngoscopy with high-frequency jet ventilation under general anesthesia with total IV anesthesia. Inductotrace® bands (Ambulatory Monitoring Inc., Ardsley, NY) were applied to the chest and abdomen in all patients and data collected from oxygen administration through emergence at 50-Hz sampling frequency in the DC mode using a 12-bit A-D converter and custom programmed LabVIEW interface. The raw data were filtered and a detector was developed based on a type I, IIR peak comb filter to differentiate apnea, cardiogenic oscillations, and jet ventilation- associated respiratory excursion. The primary end point was the ability of the detector to identify the presence of jet ventilation. Receiver operating characteristic curves were generated for the aggregate data of all patients. Respiratory inductance plethysmography reliably detected jet ventilation. The data analysis program effectively extracted a relatively small amplitude jet ventilation signal from a baseline signal contaminated by cardiogenic noise. Sensitivity was in the range of 85%, with a filter bandwidth of 0.055 Hz. Increased sensitivity with increasing filter bandwidth was offset by a detection delay of 12.5 seconds. Respiratory inductance plethysmography was successfully used to detect high-frequency jet ventilation in patients undergoing laryngotracheal surgery. This pilot study demonstrates the feasibility of respiratory inductance plethysmography as a monitor for use during jet ventilation.

A new design for high stability pressure-controlled ventilation for small animal lung imaging

We have developed a custom-designed ventilator to deliver a stable pressure to the lungs of small animals for use in imaging experiments. Our ventilator was designed with independent pressure vessels to separately control the Peak Inspiratory Pressure (PIP) and Positive End Expiratory Pressure (PEEP) to minimise pressure fluctuations during the ventilation process. The ventilator was computer controlled through a LabVIEW interface, enabling experimental manipulations to be performed remotely whilst simultaneously imaging the lungs in situ. Mechanical ventilation was successfully performed on newborn rabbit pups to assess the most effective ventilation strategies for aerating the lungs at birth. Highly stable pressures enabled reliable respiratory gated acquisition of projection radiographs and a stable prolonged (15 minute) breath-hold for high-resolution computed tomography of deceased rabbit pups at different lung volumes.

Laser-Heated Microfurnace: Gas Analysis and Graphite Morphology

We describe progress in developing a novel miniaturized laser-heated “microfurnace” aimed at preparing ultra-small (∼5 μg) graphite samples from CO2 (Smith et al. 2006, 2007, 2010). Recent effort has focused on automation of the process using a LabVIEW interface, which has permitted feedback control of the catalyst temperature as the reaction proceeds and the logging of reaction parameters. We trialed a number of different pure iron catalysts as well as Fe2O3 (which is reduced in situ to iron) and discuss the reaction rates. We studied the graphite morphology by scanning electron microscopy (SEM) and found there is a marked difference in graphite morphology with catalyst type. We assessed how each catalyst performs in the cesium sputter ion source of the ANTARES Accelerator Mass Spectrometry (AMS) facility. We utilized a quadrupole mass spectrometer to study the gas composition during the reaction, in order to better understand the underlying chemical reactions for such small samples and to better estimate the overall efficiency of the process. Results show that all CO2 is converted to CO by reduction on the iron catalyst within a few minutes of applying laser power. The reaction pressure stabilizes after 40 min; however, some CO is not converted to graphite. The cold trap temperature of –80 ° is effective at trapping H2O, so there is little CH4 production.

The Therapress 1600i: Accelerating Knee Rehabilitation

Objective: To design a ‘smart’ leg press machine that improves upon current rehabilitative practices for degenerative knee disorders such as osteoarthritis as well as injury induced knee pathologies. As its design entails, the machine provides rehabilitative assistance through strength training of upper leg muscles, with focus on the vastus medialis and vastus lateralis of the quadriceps group. The Therapress is designed to further improve the rate and quality of joint rehabilitation. The TP1600i is unique to current physical therapy practices because it incorporates three documented and proven strategies to combat quadriceps weakness: strength training, electrotherapy, and biofeedback [1,2]. The machine is designed to aid the user in regaining lost quadriceps strength, a condition indicative of poor knee health [3]. The machine incorporates a novel package of biofeedback, automated continuous variable resistance, and progress assessment, while maintaining subject specificity. The Therapress system utilizes a LabVIEW interface, which acquires and processes physiological signals recorded from the subject, as well as serves as a controller for output. These signals include surface electromyography (EMG) of the quadriceps, reaction forces at the foot (an indirect measurement of exercise resistance), and knee range of motion (ROM). Additionally, the subject is outfitted with stimulatory electrodes which function to characterize muscle recruitment using the Central Activation Ratio (CAR), as well as to therapeutically excite the muscle and induce accelerated hypertrophy [4]. Automated continuous variable resistance is achieved through a resistive hydraulic cylinder, which utilizes a servo motor to change the orifice size of partially overlapping valves during and between exercise sets. The resistance is adjusted based on user input of exertion and pain levels into the LabVIEW interface. The footplate of the machine houses four force sensing units to measure the resistance offered by the cylinder. A biofeedback arm attached to the system provides the subject with real-time data of their performance, including integrated EMG activity, ROM, and force production. Inclusion of biofeedback in quadriceps exercise regimens has been shown to increase strength gain [2]. The design allows the user to be in control of the exercise intensity at all times, while the machine works to maximize the efficacy of the protocol. The TP1600i is designed as a cost effective and time efficient alternative for the rehabilitation of debilitating knee disorders in a physical therapy protocol, and its ease of operation may qualify it for home use as well.

A Laser Scanner Based Measurement System for Quantification of Citrus Tree Geometric Characteristics

The overall goal of this study was to develop a laser scanner based measurement system and associated algorithms to measure tree geometric characteristics such as tree canopy, height, width, surface area, and volume. A measurement system, which consisted of a laser scanner, an inertial sensor, a GPS, a serial-to-USB converter, a LabVIEW interface program, and a computer, was developed and mounted on a test vehicle. The laser scanner mounted on the test vehicle vertically scanned a target tree, which was trimmed to be symmetric with respect to a vertical line on the tree trunk, using two angular resolutions of 0.25 and 0.5. The test vehicle moved along the tree-row direction at three average travel speeds of 0.63, 1.00, and 2.21 m/s. The tree geometric characteristics were estimated by three datasets: an original laser data set, a data set processed by the convex hull method, and a data set processed by the Savitzky-Golay filter. Under the experimental condition of a 0.63-m/s travel speed and a 0.25 angular resolution, the relative errors between the laser measurements and the manual measurements for tree canopy height, width, surface area, and volume were -0.37%, 0.01%, -1.99%, and 5.96%, respectively. Estimations of the tree geometric characteristics by the convex hull method were close to the manual measurements in general. Although the estimations by the original laser data set and the Savitzky-Golay filter data set deviated further from the manual measurements, the data sets could describe the profile of the tree in detail with a higher spatial resolution than that obtained by the convex hull method. It is expected that the data sets may provide more useful information in predicting tree growth and productivity. The distance error of 10 cm between the laser travel line and the tree row line caused errors of 4.0% and 9.2% in surface area and volume measurements, respectively. The laser scanner based measurement system developed in this study demonstrated that it can measure the tree geometric characteristics with a relatively good accuracy. However, measurement errors may increase for asymmetrically shaped trees.

Automatic breakdown voltage measurement of polymer films

Determining the breakdown strength of dielectric films is tedious, as the breakdown strength at 1% breakdown probability is more relevant to system insulation design than the Weibull characteristic breakdown strength, and obtaining reasonable confidence limits at 1% breakdown probability requires very large numbers of breakdowns. An automatic system for DC ramp breakdown strength measurements has been reported [1]. This system comprises a HV-probe and a movable arm equipped with an electrode holder that scans over the sample surface. One problem with this approach is that the metal electrodes are damaged by the breakdowns which, based on the author's experience, results in occasional low breakdowns that can distort the statistical distribution. To avoid this problem, a breakdown tester that can carry out breakdown strength measurements automatically utilizing metalized film electrodes has been developed. In this system, metalized films are used as electrodes and renewed after each breakdown. This is accomplished using a mechanical assembly under computer control through a LabView interface. By utilizing metalized films and renewing them after each breakdown, the system does not suffer from breakdown-induced electrode damage. To evaluate the system, we carried out 100 breakdowns with three active areas varying from 2 cm2 to 20 cm2. The breakdown data were analyzed using a Weibull distribution, agreed well with previous data obtained manually, and scaled properly as a function of area based on a Weibull distribution [2]. We have carried out over 600 breakdowns automatically, which is sufficient to provide very good data at low probability of breakdown. The development of the automatic breakdown strength tester provides a means to evaluate polymer films at low breakdown probability which is relevant to insulation design.

Imaging photomultiplier array with integrated amplifiers and high-speed USB interface

Multianode photomultiplier tube (PMT) arrays are finding application as convenient high-speed light sensitive devices for plasma imaging. This paper describes the development of a USB-based "plug-n-play" 16-channel PMT camera with 16 bits simultaneous acquisition of 16 signal channels at rates up to 2 MSs per channel. The preamplifiers and digital hardware are packaged in a compact housing which incorporates magnetic shielding, on-board generation of the high-voltage PMT bias, an optical filter mount and slits, and F-mount lens adaptor. Triggering, timing, and acquisition are handled by four field-programmable gate arrays (FPGAs) under instruction from a master FPGA controlled by a computer with a LABVIEW interface. We present technical design details and specifications and illustrate performance with high-speed images obtained on the H-1 heliac at the ANU.

Software for numerical simulation of the generation and evolution of ultrashort light pulses in active and passive systems based on micro- and nanostructured optical fibers

We present a software for a numerical simulation of the generation, propagation, and nonlinear-optical spectral and temporal evolution of ultrashort light pulses in laser systems and spectral-transformation devices based on micro- and nanostructured optical fibers. Functional modes and options offered by the developed software are explained. The LabVIEW interface allows a user to vary parameters of optical nonlinearity, gain, and loss, as well as to modify dispersion profiles of fiber components.

A high-voltage cardiac stimulator for field shocks of a whole heart in a bath

Defibrillators are a critical tool for treating heart disease; however, the mechanisms by which they halt fibrillation are still not fully understood and are the subject of ongoing research. Clinical defibrillators do not provide the precise control of shock timing, duration, and voltage or other features needed for detailed scientific inquiry, and there are few, if any, commercially available units designed for research applications. For this reason, we have developed a high-voltage, programmable, capacitive-discharge stimulator optimized to deliver defibrillation shocks with precise timing and voltage control to an isolated animal heart, either in air or in a bath. This stimulator is capable of delivering voltages of up to 500 V and energies of nearly 100 J with timing accuracy of a few microseconds and with rise and fall times of 5 micros or less and is controlled only by two external timing pulses and a control computer that sets the stimulation parameters via a LABVIEW interface. Most importantly, the stimulator has circuits to protect the high-voltage circuitry and the operator from programming and input-output errors. This device has been tested and used successfully in field shock experiments on rabbit hearts as well as other protocols requiring high voltage.