Instrument Functions Research Articles

Effects of mosaic crystal instrument functions on x-ray Thomson scattering diagnostics

Mosaic crystals, with their high integrated reflectivities, are widely employed in spectrometers used to diagnose high energy density systems. X-ray Thomson scattering (XRTS) has emerged as a powerful diagnostic tool of these systems, providing in principle direct access to important properties such as the temperature via detailed balance. However, the measured XRTS spectrum is broadened by the spectrometer instrument function (IF), and without careful consideration of the IF one risks misdiagnosing system conditions. Here, we consider in detail the IF of 40 and 100 μm mosaic Highly Annealed Pyrolytic Graphite crystals, and how the broadening varies across the spectrometer in an energy range of 6.7–8.6 keV. Notably, we find a strong asymmetry in the shape of the IF toward higher energies. As an example, we consider the effect of the asymmetry in the IF on the temperature inferred via XRTS for simulated 80 eV CH plasmas and find that the temperature can be overestimated if an approximate symmetric IF is used. We, therefore, expect a detailed consideration of the full IF will have an important impact on system properties inferred via XRTS in both forward modeling and model-free approaches.

Rubik's Cube as Reconfigurable Microfluidic Platform for Rapid Setup and Switching of Analytical Devices.

Microfluidics technology plays an important role in modern analytical instruments, while the modular design of microfluidics facilitates the reconfiguration of analytical instrument functions, making it possible to deploy on-demand systems in the field. However, modular design also faces the challenges such as connection reliability and reconfiguration convenience. Inspired by the self-locking structure of the Rubik's cube, a modular, reconfigurable microfluidic instrument architecture is proposed in this paper. The system has a self-locking structure of Rubik's cube components and an O-ring-based alignment and sealing mechanism, which enables reliable interconnection and rapid rearrangement of microfluidic modules by simply rotating the faces of the microfluidic cube. In addition, the system is capable of integrating a variety of customized modules to perform analysis tasks. A proof-of-concept application of detecting multiple pollutants in water is demonstrated to show the reconfigurable characteristics of the system. The findings of this paper provide a new idea for the design of microfluidic analytical instrument architectures.

Instrument for in situ study of rolling under normal load and torque.

Instabilities that develop at the contact interface of solid rollers or airless tires while in motion can lead to increased energy losses and reduced service life. This manuscript describes an instrument that can give better insight into the origin of such instabilities by monitoring both local and global roller mechanics. This is done by simultaneously obtaining force and displacement data from sensors as well as optical measurements and local deformation fields across two different planes, extracted from images taken by a high-speed camera. Multiple loading configurations are possible, ranging from static normal loading of the roller to free rolling and rolling with a propulsive or a braking torque. Instrument functions, elements, and design are presented in detail and its capabilities are demonstrated by obtaining measurements such as width of the contact interface under normal loading, strain fields of the roller sidewall and contact interface under normal loading, and the roller's resistance to motion for free and forced rolling.

Optical Design and Investigation of a Dual-Interference Channels and Bispectrum Static Fourier-Transform Imaging Spectrometer Based on Stepped Micro-Mirror

We demonstrate a novel tempo-spatial mixed-modulation Fourier-transform infrared imaging spectrometer. The static interference channel based on a stepped micro-mirror contributes a compact system with high stability. The instrument functions in two spectral bands ranging between 3.7- 4.8 μm and 7.7-9.3 μm, and the spectral resolution of the dual-interference channels achieves 51.5 and 4.1 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> , respectively. The instantaneous field of view is 0.15 mrad, and the working F/1.93 enables high optical throughput. The optical design and tolerance are presented with experimental investigation results, showing attractive potential in remote sensing application.

Validation of SMILES HCl profiles over a wide range from the stratosphere to the lower thermosphere

Abstract. Hydrogen chloride (HCl) is the most abundant (more than 95 %) among inorganic chlorine compounds Cly in the upper stratosphere. The HCl molecule is observed to obtain long-term quantitative estimations of the total budget of the stratospheric chlorine compounds. In this study, we provided HCl vertical profiles at altitudes of 16–100 km using the Superconducting Submillimeter-Wave Limb-Emission Sounder (SMILES) from space. The HCl vertical profile from the upper troposphere to the lower thermosphere is reported for the first time from SMILES observations; the data quality is quantified by comparison with other measurements and via theoretical error analysis. We used the SMILES level-2 research product version 3.0.0. The period of the SMILES HCl observation was from 12 October 2009 to 21 April 2010, and the latitude coverage was 40∘ S–65∘ N. The average HCl vertical profile showed an increase with altitude up to the stratopause (∼ 45 km), approximately constant values between the stratopause and the upper mesosphere (∼ 80 km), and a decrease from the mesopause to the lower thermosphere (∼ 100 km). This behavior was observed in all latitude regions and reproduced by the Whole Atmosphere Community Climate Model in the specified dynamics configuration (SD-WACCM). We compared the SMILES HCl vertical profiles in the stratosphere and lower mesosphere with HCl profiles from Microwave Limb Sounder (MLS) on the Aura satellite, as well as from the Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS) on SCISAT and the TErahertz and submillimeter LImb Sounder (TELIS) (balloon borne). The TELIS observations were performed using the superconductive limb emission technique, as used by SMILES. The globally averaged vertical HCl profiles of SMILES agreed well with those of MLS and ACE-FTS within 0.25 and 0.2 ppbv between 20 and 40 km (within 10 % between 30 and 40 km; there is a larger discrepancy below 30 km), respectively. The SMILES HCl concentration was smaller than those of MLS and ACE-FTS as the altitude increased from 40 km, and the difference was approximately 0.4–0.5 ppbv (12 %–15 %) at 50–60 km. The difference between SMILES and TELIS HCl observations was about 0.3 ppbv in the polar winter region between 20 and 34 km, except near 26 km. SMILES HCl error sources that may cause discrepancies with the other observations are investigated by a theoretical error analysis. We calculated errors caused by the uncertainties of spectroscopic parameters, instrument functions, and atmospheric temperature profiles. The Jacobian for the temperature explains the negative bias of the SMILES HCl concentrations at 50–60 km.

The Patient Perspective on Patient-Reported Outcome Measures Following Elective Hand Surgery: A Convergent Mixed-Methods Analysis

Patient-reported outcome measures (PROMs) have traditionally been used for research purposes, but are now being used to evaluate outcomes from the patient's perspective and inform ongoing management and quality of care. We used quantitative and qualitative approaches to evaluate the short-version Disabilities of the Arm, Shoulder, and Hand (QuickDASH) and the Patient-Specific Functional Scale (PSFS) with regard to patient preference and measurement of patient goals and their responsiveness after treatment. Patients 18 years or older undergoing elective hand surgery received the QuickDASH and PSFS questionnaires before and at 6 weeks after surgery. Two additional questions intended to elicit patients' preferences regarding the QuickDASH and PSFS were included. Responsiveness was measured by change in pre- to postoperative score. We analyzed patients' responses to the 2 additional questions to identify themes in PROM preferences. Results from the quantitative and qualitative analyses were combined into a convergent mixed-methods (eg, quantitative and qualitative) analysis. Thirty-eight patients completed preoperative questionnaires; 25 (66%) completed postoperative questionnaires. Seventeen patients (77%) preferred the PSFS, 3 (14%) had no preference, 2 (9%) preferred the QuickDASH. The average change from pre- to postoperative QuickDASH was -10 (SD, 20), and that of the PSFS was -27 (SD, 26). Ten patients (40%) reported QuickDASH score changes above the minimal clinically importance difference (MCID), 17 patients (68%) reported PSFS score changes above the MCID. Content analysis revealed 4 themes in preference for a PROM: instrument simplicity (ease of instrument understanding and completion), personalized assessment (individualization and relevance), goal directed (having measurable aims or objectives), distinct items (concrete or specific instrument items or functions). Most patients felt the PSFS better measured their goals because it is a simple, personalized instrument with distinct domains. Whereas standardized PROMs may better compare across populations, physicians, or conditions, employing PROMs that address patient-specific goals may better assess aspects of care most important to patients. A combination of these 2 types of PROMs can be used to assess outcomes and inform quality of care.

The small-deflection energy analyzer (SDEA): Enabling multi-point investigations in the thermosphere-ionosphere.

The Small-Deflection Energy Analyzer (SDEA), a new type of parallel plate analyzer of high sensitivity and resolution, enables CubeSat applications for new ionosphere-thermosphere investigations. SDEA's data of angle-energy distributions yield the thermosphere-ionosphere parameters of neutral wind and ion-drift vectors with corresponding temperatures and densities. Less than 4 cm in total length and 2 cm on the side, SDEA is used in the wind-temperature and ion-drift temperature spectrometers pair to provide two of the three instrument functions in the Wind-Ion-Neutral-Composition Suite now operating in three satellites in a low-Earth orbit. The small-deflection feature of SDEA allows miniaturization with several advantages discussed within. A description of SDEA is followed by examples of laboratory and a limited amount of flight data taken in low-Earth-orbit to demonstrate precision possible with SDEA. Strengths and weaknesses are discussed.

Terra MODIS: 20 years of on-orbit calibration and performance

Since its launch in December 1999, Terra Moderate Resolution Imaging Spectroradiometer (MODIS) has successfully operated for more than 20 years, with its observations generating a broad range of science data products that have greatly enabled the remote sensing community and users worldwide in their studies of many key geophysical parameters of the Earth’s systems. MODIS collects data in 36 spectral bands, covering wavelengths from 0.41 to 14.4 μm, which are calibrated by a set of onboard calibrators (OBCs). Also contributing to the sensor’s mission-long on-orbit calibration and characterization are near-monthly scheduled lunar observations and multiple time series of the sensor’s responses over select ground targets at a variety of scan angles. To a large extent, the quality of MODIS data products relies strongly on the dedicated efforts to operate and calibrate the instrument, to derive and update calibration parameters, and to develop and implement new calibration strategies and algorithms in response to on-orbit changes of the sensor’s characteristics and its OBC functions. We provide an overview of the Terra MODIS on-orbit operation and calibration activities over the last 20 years, including changes made to extend and preserve the instrument and OBC functions and their operation strategies. It also illustrates the sensor’s on-orbit performance with results derived from its OBC, lunar observations, and select ground targets and discusses major changes in sensor characteristics and corrections applied to the L1B algorithms as well as calibration lookup table updates. To date, the Terra MODIS instrument and its OBCs continue to operate and function normally. Except for those identified prelaunch, most spectral bands and detectors continue to meet their specified calibration requirements. Also discussed in our paper are lessons learned from Terra MODIS operation and calibration, as well as future efforts to further extend and maintain the quality of its long-term data records.

Review on Common Observed HPLC Troubleshooting Problems

HPLC provide much higher resolution, more accurate quantitative results, as well as shorter analysis times in comparison to the earlier techniques, HPLC has evolved into an indispensable tool in many analytical laboratories. Troubleshooting is a form of problem solving, often applied to repair failed products or processes. Actually, HPLC refers to a number of separation techniques that use a liquid mobile phase, or eluent. Troubleshooting HPLC instrumentation and separations require a fundamental understanding of how the instrument functions and how the separation works. Common HPLC problems are caused by component malfunctions (pump, degasser, injector, detector, data system, column), and faulty preparation of the mobile phase or sample preparation. Always use well cleaned glassware for preparation for better results. Main key to resolve HPLC problem is Cleaning of HPLC with appropriate solvent. If any problem occurs, it is advisable to perform a quick visual check of the instrument and column. If Monograph or any protocol is provided then try to follow same process. Troubleshooting is a form of problem solving, often applied to repair failed products or processes. Otherwise, we suggest that you read the entire article so as to pick up some ideas that will help you avoid problems in the future. We hope that this article useful to diagnose problems and to gain understanding of underlying causes so that you can prevent or minimize future occurrence. Colum and HPLC care is most important part of troubleshooting. In This article, we tried to cover all major troubleshooting problems.

Common‐Volume Dual‐Frequency Radar Observations of 150‐km Echoes and Implications

AbstractWe present and discuss common‐volume dual‐frequency radar observations of 150‐km echoes made at 30 and 53 MHz from Gadanki by employing identical transmitter power and antenna beam width. These controlled experiments reveal that 150‐km echoes are stronger, broader in spectral width, and more frequent in their occurrence at 30 MHz than at 53 MHz. Echo intensities at 30 and 53 MHz are found to be consistent with the rocket‐borne observations of wave number spectrum of meter‐scale irregularities in the 150‐km region. The frequency dependence of spectral widths of the echoes while is found to be somewhat similar to that of electrojet type‐1 echoes it is opposite to that of electrojet type‐2 echoes and also to that of incoherent scattering in direction perpendicular to magnetic field. Spectral widths of the echoes observed by both radars are found to be independent of SNR. A detailed comparison of these observations with those made earlier suggests that instrument functions play an important role in manifesting SNR‐dependent/independent spectral width property of the 150‐km echoes. The narrow spectral properties and frequency dependence of echo intensity and spectral width clearly suggest that the irregularities responsible for the radar backscatter are linked with weak plasma turbulence and the meter‐scale irregularities responsible for radar echoes ought to be growing with direct injection of energy at the meter scale itself to overcome damping. We surmise the potential role of photoelectrons and atmospheric gravity waves in the underline plasma instability process.

Some Results of Designing an IIR Smoothing Filter with P- Splines

Requirements for modern digital filters are high and depend on some selective properties of such filters. IIR filters can ensure the narrowest transition width of signal omission and suppression with the same DF order. This study proposes to design and analyze a software-based IIR filter, a digital filter (DF) that is based on simple mathematical basis facilitates subsequent interpretation of data (estimation of derivatives, trends, forecast of time series, etc.). A modified penalty spline has been used as a model for such digital software-based IIR filter. A recurrent form of the P-spline computation has been created for the the IIR spline filter. The new modified recurrent P-spline can be used for stand-alone or group data. The recurrent spline filter has been investigated by the methods of linear dynamic systems. The obtained difference equation of the spline transform corresponds to a linear recursive DF with constant parameters. Frequency and time characteristics of the DF, being the main characteristics system and instrument functions, have been obtained analytically. The system function has been used to investigate the frequency characteristics of the spline filter and it has been found out that the spline filter is low frequency throughout the entire variation range of the spline parameters. Such filter characteristics correspond to a second-order aperiodic segment or a system with delay, which is typical for grouped data processing. The selective properties of the spline filter are clearly illustrated with the width of the instrument function, which depends on the spline parameters. Studies have shown that the passband bandwidth is mostly influenced by the group data size (the number of non-recursive terms of the difference equation). The stability of the recursive spline filter has been also estimated analytically based on the characteristic equation and the Hurwitz criterion. DF is always stable only when the conjugation of recurrent coefficients occurs at the beginning of a spline segment. Frequency characteristics of the spline filter have been confirmed in the time domain by histograms of the remainders of two recovered model functions.

Option Arbitrage and Quantification Realization Based on Time Value

Option is a very important financial derivative instrument, with hedging, speculation, price discovery and other functions. Based on the option parity formula, this paper finds out that the time value of the option has arbitrage opportunity by studying the spot price of the 50ETF and 50ETF fund. According to the relationship between the time value of the option and the trend of the subject matter, some arbitrage strategies are developed. The result of the last back test shows that these strategies have a good return.

Model-Based Digital Pianos: From Physics to Sound Synthesis

As a result of their complexity and versatility, pianos are arguably one of the most important instruments in Western music. The size, weight, and price of grand pianos as well as their relatively simple control surface (i.e., the keyboard), have led to the development of digital counterparts that mimic the sound of acoustic pianos as closely as possible. While most commercial digital pianos are based on sample playback, it is also possible to reproduce a piano's sound by modeling the physics of the instrument. The process of physical modeling starts with first understanding the physical principles, followed by creating accurate numerical models, and finally, finding numerically optimized signal processing models that allow sound synthesis in real time by excluding inaudible phenomena and adding some perceptually important features by using signal processing tricks. Accurate numerical models can be used by physicists and engineers to understand how the instrument functions or to help piano makers with instrument development. On the other hand, efficient real-time models are geared toward composers and musicians who perform at home or onstage. This article provides an overview of a physics-based piano synthesis beginning with computationally heavy, physically accurate approach followed by a discussion of the approaches that are designed to produce the best possible sound quality for real-time synthesis.

Preflight Evaluation of the Performance of the Chinese Environmental Trace Gas Monitoring Instrument (EMI) by Spectral Analyses of Nitrogen Dioxide

The Environmental trace gas Monitoring Instrument (EMI) onboard the Chinese high-resolution remote sensing satellite GaoFen-5 is an ultraviolet–visible imaging spectrometer, aiming to quantify the global distribution of tropospheric and stratospheric trace gases and planned to be launched in spring 2018. The preflight calibration phase is essential to characterize the properties and performance of the EMI in order to provide information for data processing and trace gas retrievals. In this paper, we present the first EMI measurement of nitrogen dioxide (NO2) from a gas absorption cell using scattered sunlight as the light source by the differential optical absorption spectroscopy technique. The retrieved NO2 column densities in the UV and Vis wavelength ranges are consistent with the column density in the gas cell calculated from the NO2 mixing ratio and the length of the gas cell. Furthermore, the differences of the retrieved NO2 column densities among the adjoining spatial rows of the detector are less than 3%. This variation is similar to the well-known “stripes-pattern” of the Ozone Monitoring Instrument and is probably caused by remaining systematic effects like a nonperfect description of the individual instrument functions. Finally, the signal-to-noise ratios of EMI in-orbit measurements of NO2 are estimated on the basis of on-ground scattered sunlight measurements and radiative transfer model simulations. Based on our results, we conclude that the EMI is capable of measuring the global distribution of the NO2 column with the retrieval precision and accuracy better than 3% for the tested wavelength ranges and viewing angles.

Recovery of Images Distorted by an Instrument Function with Unknown Side Lobes

A method for compensating the influence of unknown side lobes of a distorting instrument function on the quality of image recovery is proposed. A processing algorithm, based on the knowledge of the main lobe of the instrument function and its spectrum together with a universal reference spectrum, is used to compensate the contribution of the unknown side lobes to the spectrum of the distorted image. The stability of the method to the noise inherent in the improved images and various forms of distorting instrument functions is analyzed. High efficiency of the method of compensation is demonstrated in the cases in which the total contribution from the unknown side lobes to the resulting brightness of the distorted image significantly (four-fold) exceeds the contribution from the main lobe.

Automated Microfluidic Instrument for Label-Free and High-Throughput Cell Separation.

Microfluidic technologies for cell separation were reported frequently in recent years. However, a compact microfluidic instrument enabling thoroughly automated cell separation is still rarely reported until today due to the difficult hybrid between the macrosized fluidic control system and the microsized microfluidic device. In this work, we propose a novel and automated microfluidic instrument to realize size-based separation of cancer cells in a label-free and high-throughput manner. Briefly, the instrument is equipped with a fully integrated microfluidic device and a set of robust fluid-driven and control units, and the instrument functions of precise fluid infusion and high-throughput cell separation are guaranteed by a flow regulatory chip and two cell separation chips which are the key components of the microfluidic device. With optimized control programs, the instrument is successfully applied to automatically sort human breast adenocarcinoma cell line MCF-7 from 5 mL of diluted human blood with a high recovery ratio of ∼85% within a rapid processing time of ∼23 min. We envision that our microfluidic instrument will be potentially useful in many biomedical applications, especially cell separation, enrichment, and concentration for the purpose of cell culture and analysis.

The Raman Laser Spectrometer for the ExoMars Rover Mission to Mars

Abstract The Raman Laser Spectrometer (RLS) on board the ESA/Roscosmos ExoMars 2020 mission will provide precise identification of the mineral phases and the possibility to detect organics on the Red Planet. The RLS will work on the powdered samples prepared inside the Pasteur analytical suite and collected on the surface and subsurface by a drill system. Raman spectroscopy is a well-known analytical technique based on the inelastic scattering by matter of incident monochromatic light (the Raman effect) that has many applications in laboratory and industry, yet to be used in space applications. Raman spectrometers will be included in two Mars rovers scheduled to be launched in 2020. The Raman instrument for ExoMars 2020 consists of three main units: (1) a transmission spectrograph coupled to a CCD detector; (2) an electronics box, including the excitation laser that controls the instrument functions; and (3) an optical head with an autofocus mechanism illuminating and collecting the scattered light from t...

Expected signatures from hadronic emission processes in the TeV spectra of BL Lacertae objects

Context. The wealth of recent data from Imaging Air Cherenkov telescopes (IACTs), ultra-high energy cosmic-ray experiments and neutrino telescopes have fuelled a renewed interest in hadronic emission models for γ-loud blazars. Aims. We explore physically plausible solutions for a lepto-hadronic interpretation of the stationary emission from high-frequency peaked BL Lac objects (HBLs). The modelled spectral energy distributions are then searched for specific signatures at very high energies that could help to distinguish the hadronic origin of the emission from a standard leptonic scenario. Methods. By introducing a few basic constraints on parameters of the model, such as assuming the co-acceleration of electrons and protons, we significantly reduced the number of free parameters. We then systematically explored the parameter space of the size of the emission region and its magnetic field for two bright γ-loud HBLs, PKS 2155-304 and Mrk 421. For all solutions close to equipartition between the energy densities of protons and of the magnetic field, and with acceptable jet power and light-crossing timescales, we inspected the spectral hardening in the multi-TeV domain from proton-photon induced cascades and muon-synchrotron emission inside the source. Very-high-energy spectra simulated with the available instrument functions from the future Cherenkov Telescope Array (CTA) were evaluated for detectable features as a function of exposure time, source redshift, and flux level. Results. A range of hadronic scenarios are found to provide satisfactory solutions for the broad band emission of the sources under study. The TeV spectrum can be dominated either by proton-synchrotron emission or by muon-synchrotron emission. The solutions for HBLs cover a parameter space that is distinct from the one found for the most extreme BL Lac objects in an earlier study. Over a large range of model parameters, the spectral hardening due to internal synchrotron-pair cascades, the “cascade bump”, should be detectable for acceptable exposure times with the future CTA for a few nearby and bright HBLs.

The association between singing and/or playing a musical instrument and cognitive functions in older adults

ABSTRACTObjectives: Cognitive decline happens to everyone when aging, but to some more than others. Studies with children, adults, and professional musicians suggest that making music could be associated with better cognitive functioning. In older adults however, this association is less well investigated, which is therefore the aim of this study.Methods: In this cross-sectional study data from 1101 participants aged 64 and older from the Longitudinal Aging Study Amsterdam were used. Multivariable linear regression analyses were performed to test the association between making music and cognitive functioning and time spent making music and cognitive functioning. ANCOVA analyses were performed to differentiate between participants who made no music, only sang, only played an instrument or both sang and played an instrument in terms of cognitive functioning.Results: Making music was significantly positively associated with letter fluency, learning and attention/short-term memory. Time spent making music yielded no significant results. The ANCOVA analyses showed higher scores for participants who only played an instrument compared to participants who made no music on learning, working memory and processing speed. For processing speed the instrument only group also had a higher score than participants who only sang.Discussion: Making music at least once every two weeks and especially playing a musical instrument, is associated with better attention, episodic memory and executive functions. The results suggest that making music might be a potential protective factor for cognitive decline; however, to support this notion a longitudinal study design is needed.

Elimination of Sensor Maintenance By Sensor Interrogation and Correction

Amperometric electrochemical gas sensors are virtually ubiquitous and well accepted in industrial hygiene and personal safety applications. This sensor type, used initially for detection of carbon monoxide (CO) and oxygen (O2), first appeared in the 1970s. Since that time, sensors were developed to detect many other gases of interest, including hydrogen sulfide (H2S), sulfur dioxide (SO2) and chlorine (Cl2), just to name a few. Electrochemical sensors are highly accurate, have good reproducibility and linearity and are long-lived. That said, best industry practice dictates that gas detection instruments be tested regularly (every day that the instrument is used) to ensure proper functionality. Testing can take several forms, including full calibration using the test gas of interest or a simulant gas, or a calibration check or bump test. Each test requires considerable monetary investment, including a test gas source (usually a compressed gas cylinder) and delivery system that typically includes a pressure regulator and tubing. It is quite common at large industrial installations that all personnel are equipped with personal gas detectors. Clearly, providing test gas and delivery systems is a significant investment in equipment, consumables and non-productive time. This paper discusses a new gas-free bump test and correction system that eliminates the need for test gas and delivery systems, while providing on-demand exercising of all sensor and instrument functions, real time sensor signal correction for sensor aging and response to environmental conditions.[1],[2] This new sensor technology is based upon a modification dual channel amperometric gas sensor. Dual channel amperometric gas sensors have two separate working electrodes include one that is designed for carbon monoxide detection and the other intended for hydrogen sulfide detection. These two independent electrodes share a common reference electrode1,2 (RE) and counter1,2 electrode (CE). In the present application, bias potentials applied to the two working electrodes are controlled by an on-board Application Specific Integrated Circuit (ASIC). This ASIC chip also amplifies and measures currents that flow between the two working electrodes and common counter electrode. The present technology, first introduces as the H2S Pulse Sensor, also has two separate working electrodes, one to sense hydrogen sulfide, (as with a two-tox sensor) and a second electrode that responds to oxygen. Pulse Technology functions in the following manner: first, a small potential pulse is applied to the H2S working electrode; this potential pulse causes electrical current to flow between the H2S working electrode and the common counter electrode. This current is measured and analyzed by the ASIC. The current that flows within the sensor can be used to monitor or measure several items: Is the sensor present?Is the sensor conducting current?Has sensor sensitivity changed from the last pulse test?Has sensor sensitivity sensor changed enough to require re-calibration (an actual re-calibration using test gas), orCan sensor output be corrected slightly in order to maintain maximum sensor accuracy? The electrical pulse test can also determine if the sensor’s working electrode was poisoned or inhibited by an interferant gas. Immediately following the pulse test, the second oxygen-responsive working electrode is activated by the ASIC and allowed to briefly equilibrate. Once appropriate current is established for oxygen reduction in ambient air, users are prompted to exhale into the sensor inlet. Exhaled breath contains approximately 15 vol-% oxygen as compared to ambient air that contains 20.8 vol-% oxygen. Decrease in oxygen due to exhaled breath pulse supplied by users causes decrease in current that flows between the oxygen-responsive working electrode and the common counter electrode. This current change is also measured and analyzed by the ASIC. The change in current due to exhaled breath is used to determine if gaseous flow path into the sensor is free of obstruction as compared to the last successful pulse test. The exhaled breath pulse test can discriminate between open, partially-blocked and fully-blocked flow paths. Pulse Technology combines these two independent sensor function tests to provide a convenient and highly accurate and effective substitute for bump testing using calibration gas. Extensive testing of Pulse Technology indicates greater than 98% accuracy. Pulse Technology effectively eliminates daily bump testing using calibration gas and extends the interval between required full calibrations. [1]Scheffler, T. B., Devices, systems and methods for testing gas sensors and correcting gas sensor output, U.S. Patent 7,413,645 B2, August 19, 2008. [2]Scheffler, T. B., Devices, systems and methods for testing gas sensors and correcting gas sensor output, U. S. Patent 7,959,777 B2, June 14, 2011. Figure 1