IR Channels Research Articles

Pharmacological characterization of cellular mechanisms of the renal vasodilatory effect of nicotine in rats

Nicotine causes vasodilation in the renal vasculature through as yet unidentified mechanism. This study investigated the role of endothelial and non-endothelial factors in the vasodilatory action of nicotine in the rat isolated kidney. Nicotine vasodilation in phenylephrine-preconstricted perfused kidneys was evaluated in the absence and presence of drugs that interfere with nitric oxide synthase (NOS), K + channels, cholinergic or adrenergic activity. Nicotine infusion (5 × 10 − 5 , 1 × 10 − 4 , and 5 × 10 − 4 M) produced concentration-dependent decreases in the renal perfusion pressure, which continued for 20 min with a peak depressor effect observed at approximately 3 min. Nicotine vasodilation was associated with increases in norepinephrine and NO metabolites (nitrite/nitrate, NOx) levels in the renal effluent. Chemical denudation of the endothelium with 3-[(3-cholamidopropyl)-dimethyl-ammonio]-1-propane-sulfonate (CHAPS), or inhibition of NOS (N G-nitro-L-arginine, L-NNA), or guanylate cyclase (methylene blue) almost abolished the renal vasodilatory action of nicotine. Nicotine vasodilation was also significantly attenuated after selective blockade of ATP-sensitive (K ATP, glibenclamide) or inward rectifier (K ir, BaCl 2) K + channels but remained unaltered after blockade of large-conductance calcium-activated (BK Ca, tetraethylammonium, TEA) or voltage-dependent (K v, 4-aminopyridine) K + channels. Hexamethonium (ganglionic blocker), propranolol (β-adrenceptor blocker), guanethidine (adrenergic neuron blocker), atropine (muscarinic antagonist) or the use of kidneys preconstricted with 80 mM KCl reduced the vasodepressor action of nicotine. Finally, exposure to diclophenac or neostigmine had no effect on nicotine vasodilation. Together, these findings implicate endothelial NOS and K ATP and K ir channels in the renal vasodepressor effect of nicotine. Further, the sympathetic-dependent NO-mediated neurogenic vasodilation apparently contributes, at least partly, to nicotine vasodilation.

Evaluating the calibration of MTSAT‐1R infrared channels using collocated Terra MODIS measurements

The calibration of four MTSAT‐1R infrared channels was evaluated by comparing MTSAT measurements with Terra/MODIS inferred MTSAT‐equivalent brightness temperatures during August 2005 and August 2006. Theoretical relationships converting MODIS brightness temperatures to MTSAT‐equivalent values were obtained and used for the comparison. Results indicate that MTSAT two split window channels are well calibrated, and no serious systematic errors or biases are found; and the MTSAT water‐vapour channel shows a good linear relationship but with a warm bias up to 2 K. The significant cold bias of MTSAT 3.7 µm channel about −6.7 K in August 2005 is found to be much removed in August 2006, after correction of the electrical crosstalk between MTSAT‐1R SWIR channel and WV channel starting from March 2006. Since then, calibration performances of MTSAT‐1R split window channels and shortwave IR channel seem to be comparable with MODIS calibration, while the water‐vapour channel shows more uncertainties up to 2 K of bias.

Miniaturization and HTS of a FRET-Based Membrane Potential Assay for Kir Channel Inhibitors

The K(ir) family of potassium-selective ion channels is characterized by their inward (anomalous) rectifying current-voltage relationship. K(ir) channels are widely expressed in mammalian cells and through their role in regulation of the cell membrane potential have been implicated in diverse physiological functions. To enable the identification of novel K(ir) channel inhibitors, a fluorescence resonance energy transfer (FRET)-based membrane potential assay was developed using a Chinese hamster ovary cell line stably expressing a human K(ir) channel. The FRET-based assay incorporates the use of two dyes {N-(6-chloro-7-hydroxycoumarin-3-carbonyl)-dimyristoylphosphatidylethanolamine (CC2-DMPE) and bis(1,3-diethylthiobarbiturate)trimethine oxonol [DiSBAC(2)(3)]} to track changes in membrane potential, thus enabling all of the advantages of ratiometric readout: reduced inaccuracies arising from well-to-well variation in cell number, dye loading, signal intensities, and plate inconsistencies. The assay was miniaturized to a 1,536-well microtiter plate format and read on a fluorometric imaging plate reader (FLIPR(Tetra), Molecular Devices, Sunnyvale, CA). The assay was automated and utilized to perform a primary high-throughput screening campaign to identify novel inhibitors of the K(ir) channel.

A Remote Sensed Data Combined Method for Sea Fog Detection

Steam and advection fogs are frequently observed in the Yellow Sea from March to July except for May. This study uses remote sensing (RS) data for the monitoring of sea fog. Meteorological data obtained from the Ieodo Ocean Research Station provided a valuable information for the occurrence of steam and advection fogs as a ground truth. The RS data used in this study were GOES-9, MTSAT-1R images and QuikSCAT wind data. A dual channel difference (DCD) approach using IR and shortwave IR channel of GOES-9 and MTSAT-1R satellites was applied to detect sea fog. The results showed that DCD, texture-related measurement and the weak wind condition are required to separate the sea fog from the low cloud. The QuikSCAT wind data was used to provide the wind speed criteria for a fog event. The laplacian computation was designed for a measurement of the homogeneity. A new combined method, which includes DCD, QuikSCAT wind speed and laplacian computation, was applied to the twelve cases with GOES-9 and MTSAT-1R. The threshold values for DCD, QuikSCAT wind speed and laplacian are -2.0 K, 8 m s-1 and 0.1, respectively. The validation results showed that the new combined method slightly improves the detection of sea fog compared to DCD method: improvements of the new combined method are 5 ~ 6 % increases in the Heidke skill score, 10% decreases in the probability of false detection, and 30 ~ 40% increases in the odd ratio.

Influence of chronic alcohol consumption on inward rectifier potassium channels in cerebral arterioles

Inward rectifier potassium (K IR) channels appear to play an important role in the regulation of cerebral blood flow. Our goal was to examine the influence of chronic alcohol exposure on K IR channels in cerebral arterioles. Sprague–Dawley rats were fed liquid diets with or without alcohol for 8–12 weeks. Using intravital microscope, we measured diameter of pial arterioles in response to an inhibitor, BaCl 2, and an activator, KCl, of K IR channels in the absence and presence of a scavenger of reactive oxygen species, tempol, or an inhibitor of NAD(P)H oxidase, apocynin. Application of BaCl 2 (30 and 100 μM) produced dose-related vasoconstriction in non-alcohol-fed, but not in alcohol-fed rats. In addition, application of KCl (3, 10, and 30 mM) produced dose-related dilation in non-alcohol-fed and alcohol-fed rats, but the magnitude of vasodilatation was less in alcohol-fed rats. In contrast, nitroglycerin-induced vasodilation was similar in non-alcohol-fed and alcohol-fed rats. Superfusion of cranial window with tempol (0.1 mM) or apocynin (1 mM) did not alter baseline diameter and nitroglycerin-induced dilation of pial arterioles in non-alcohol-fed and alcohol-fed rats but significantly improved impaired KCl-induced dilation in alcohol-fed rats. Our findings suggest that chronic alcohol consumption impairs the role of K IR channels in basal tone and KCl-induced dilation of cerebral arterioles. In addition, impaired KCl-induced dilation of cerebral arterioles during alcohol consumption may be related to enhanced release of oxygen-derived free radicals via NAD(P)H oxidase.

K ir and K v channels regulate electrical properties and proliferation of adult neural precursor cells

The functional significance of the electrophysiological properties of neural precursor cells (NPCs) was investigated using dissociated neurosphere-derived NPCs from the forebrain subventricular zone (SVZ) of adult mice. NPCs exhibited hyperpolarized resting membrane potentials, which were depolarized by the K + channel inhibitor, Ba 2+. Pharmacological analysis revealed two distinct K + channel families: Ba 2+-sensitive K ir channels and tetraethylammonium (TEA)-sensitive K v (primarily K DR) channels. Ba 2+ promoted mitogen-stimulated NPC proliferation, which was mimicked by high extracellular K +, whereas TEA inhibited proliferation. Based on gene and protein levels in vitro, we identified K ir4.1, K ir5.1 and K v3.1 channels as the functional K + channel candidates. Expression of these K + channels was immunohistochemically found in NPCs of the adult mouse SVZ, but was negligible in neuroblasts. It therefore appears that expression of K ir and K v (K DR) channels in NPCs and related changes in the resting membrane potential could contribute to NPC proliferation and neuronal lineage commitment in the neurogenic microenvironment.

Evaluation of cropfield water supply by remote sensing method

This study is performed to assess the availability of METEOSAT satellite images to establish daily mean areal rainfall over a part of the Great Hungarian Plain using VIS, IR and WV channels. Principal components analysis was running, and the image possessed by the major information content was examined. Spatial evaluation of the component weights was performed. NDVI was computed and a mask was built for the NDVI image to select clouds by a threshold value of 0,15. Cross-correlation was computed between the images of the three channels. Strong correlation was found between VIS-IR and VIS-WV channels. Correspondence between satellite average pixel values around the raingauge sites and raingauge-derived rainfall values were examined. We established that inquiry of a longer period give better correlation value, so we suggest the utilization of satellite-based rainfall estimates for not daily estimation, but for longer period estimation to get more accurate data in certain ecological units that may contribute to establish sustainable cropping systems.

The RF-LLK optoelectronic active-passive system for forming brightness-range images of the background-and-target situation

The RF-LLK optoelectronic active-passive system is intended for obtaining and forming passive IR brightness images (wavelength range 8-14 µm) and laser brightness and range images (working wavelength 1.54 µm) of the background-and-target situation. Flight testing showed high information content of the combined images of the passive IR and laser (brightness and range-measuring) channels.

Exploration of Mars in SPICAM-IR experiment onboard the Mars-Express spacecraft: 1. Acousto-optic spectrometer SPICAM-IR

The acousto-optic spectrometer of the near infrared range, which is a part of the spectrometer SPICAM onboard the Mars-Express spacecraft, began to operate in the orbit of Mars in January 2004. In the SPICAM experiment, a spectrometer on the basis of an acousto-optic filter was used for the first time to investigate other planets. During one and a half years of operation, the IR channel of SPICAM obtained more than half a million spectra in the 1–1.7 μm range with a resolving power of more than 1500 in different modes of observation: limb, nadir, and solar eclipses. The main goal of the experiment is to study the content of water vapor in the Martian atmosphere by measuring the absorption spectrum in the 1.38 μm band. Characteristics of the instrument (high spectral resolution and signal-to-noise ratio) allow one to solve a number of additional scientific problems including the study of ozone distribution by emission of singlet oxygen (O21Δg), detection of the water and carbonic dioxide ices, and also the study of the vertical distribution and optical characteristics of aerosol in the Martian atmosphere. We present a description of the instrument, the results of its ground and in-flight calibrations, and a brief survey of the basic scientific results obtained by the SPICAM spectrometer during a year-and-half of operation.

Cholinergic modulation of neurons in the gustatory region of the nucleus of the solitary tract

The rostral portion of the nucleus of the solitary tract (rNST) is an obligatory relay for gustatory afferent input on its way to the forebrain. Previous studies have demonstrated excitation of rNTS neurons by glutamate and substance P and inhibition by γ-aminobutyric acid (GABA) and met-enkephalin (ENK). Despite the existence of cholinergic neurons and putative terminals within the rNTS, there are no data on the effects of acetylcholine (ACh) on rNTS processing. Here, we use patch-clamp recording of rNTS neurons in vitro to examine ACh-mediated responses and voltage-gated conductances in these cells. Results revealed (1) intrinsic voltage-gated inhibition via activation of voltage-gated potassium A-channels ( I A), found almost exclusively in the medial rNTS, and hyperpolarization-activated potassium/sodium channels ( I h), found more frequently in the lateral rNST; and (2) ligand-gated inhibition via activation of muscarinic m2 ACh receptors (mAChRs) linked to inward rectifier potassium channels ( K ir) evenly distributed throughout the rNTS, a mechanism dependent on cholinergic inputs. Muscarinic responses were blocked by AFDX-116, a selective m2 mAChR antagonist, and by BaCl 2, an antagonist of K ir channels. In addition, many rNTS neurons exhibited excitation via α7 and non-α7 nicotinic AChRs. Non-α7 nAChRs, blocked by 10 μM mecamylamine, occurred more frequently in the lateral rNTS. In contrast, α7 nAChRs, blocked by 20 nM methyllcaconitine, were evenly distributed across the nucleus. As previously reported for voltage-activated conductances, none of these currents was related to neuronal morphology. These voltage- and ligand-dependent inhibitory mechanisms would be expected to contribute to the modulation of gustatory processing through the NST.

Endothelial mediators of the acetylcholine-induced relaxation of the rat femoral artery

This study examined endothelium-derived mediators of acetylcholine-induced relaxation in male rat femoral arteries. Arterial rings were suspended in a myograph for the measurement of isometric force. The generation of hydrogen peroxide (H 2O 2) in endothelial cells was detected using the fluorescent probe, 5-(and-6)-chloromethyl-2′,7′-dichlorodihydrofluorescein diacetate acetyl ester. N G-nitro- l-arginine methyl ester (L-NAME, NOS inhibitor) and 1H-[1,2,4]oxadiazolo[4,2-α]quinoxalin-1-one (ODQ, guanylate cyclase inhibitor) alone or in combination with indomethacin (cycloxygenase inhibitor) diminished acetylcholine-induced endothelium-dependent relaxation to a similar extent. A small relaxation to acetylcholine in 60 mM KCl-constricted rings was abolished by L-NAME. Acetylcholine-induced relaxation was reduced by charybdotoxin plus apamin (intermediate- and small-conductance Ca 2+-activated K + channel blockers, respectively) or by 30 mM KCl. Both ouabain (Na +/K + ATPase inhibitor) and BaCl 2 (K IR channel blocker) also inhibited the relaxation albeit to a lesser degree. In the presence of L-NAME, ODQ plus indomethacin, charybdotoxin plus apamin or ouabain plus BaCl 2 produced further inhibition. Catalase attenuated acetylcholine-induced relaxations and this attenuation was prevented by 3-amino-1,2,4-triazole (catalase inhibitor). Catalase did not affect acetylcholine-induced relaxations in rings treated with L-NAME or ODQ. Acetylcholine increased the dichlorofluorescein fluorescence intensity in native endothelial cells and this effect was abolished by catalase and by L-NAME. Exogenous H 2O 2 caused endothelium-independent relaxation that was slightly inhibited by iberiotoxin, ODQ or significantly reduced by elevated KCl, and abolished by catalase. The present results indicate that in addition to nitric oxide (NO) and endothelium-derived hyperpolarizing factor (EDHF, sensitive to charybdotoxin plus apamin, ouabain, and BaCl 2), the endothelium of rat femoral artery can release H 2O 2 in response to acetylcholine, which was sensitive to L-NAME. Thus, the eNOS-dependent H 2O 2 is likely to be the third mediator of acetylcholine-mediated relaxations in rat femoral arteries.

Tropospheric water and temperature retrieval for ASMUWARA

The retrieval of tropospheric water and temperature with the ground-based and automatically operating radiometer system ASMUWARA (All-Sky MUlti WAvelength RAdiometer) is described. This instrument operates simultaneously at microwave and IR channels. Integrated water vapour (IWV) and integrated liquid water (ILW) are retrieved with a newly developed linear algorithm to an accuracy of 0.014 kgm -2 (ILW) and 0.41 kgm -2 (IWV), thanks to the inclusion of a channel at 151 GHz. These measurements are made for the whole hemisphere and therefore provide information about the spatial distribution of water in the troposphere. With an optimal estimation algorithm, tropospheric temperature and humidity profiles are retrieved. The results are quasi bias free with a mean error of less than 2.5 K for the temperature (less than 1 K in the lowest km above ground), and less than 1 gm -3 for the humidity. Examples of all measurements are shown.

Study of the character of the time dependence of the ratio of signals in the IR and visible channels of a radiometric apparatus when fragments of space junk are observed

A more accurate expression is derived for determining the specific load of fragments of space junk via the time dependence of the ratio of signals in the IR and visible channels of on-board radiometric observation apparatus. Results are presented of a calculation of the time behavior of this ratio when aluminum and plastic debris is observed on near-earth orbits. The cases considered here involve constant heating of the debris by solar radiation and the variation of this heating according to a harmonic law because the debris rotates around its center of mass.

Protein kinase A-dependent activation of inward rectifier potassium channels by adenosine in rabbit coronary smooth muscle cells

We studied the effect of adenosine on the Ba 2+-sensitive K IR channels in the smooth muscle cells isolated from the small-diameter (<100 μm) coronary arteries of rabbit. Adenosine increased K IR currents in concentration-dependent manner (EC 50 = 9.4 ± 1.4 μM, maximum increase of 153%). The adenosine-induced stimulation of K IR current was blocked by adenylyl cyclase inhibitor, SQ22536 and was mimicked by adenylyl cyclase activator, forskolin. The adenosine-induced increase of current was blocked by cyclic AMP-dependent protein kinase (PKA) inhibitors, KT 5720 and Rp-8-CPT-cAMPs. The adenosine-induced increase of K IR currents was blocked by an A 3-selective antagonist MRS1334, while the antagonists of other subtypes (DPCPX for A 1, ZM241385 for A 2A, and alloxazine for A 2B) were all ineffective. Furthermore, an A 3-selective agonist, 2-Cl-IB-MECA induced increase of K IR currents. We also examined the effect of adenosine on coronary blood flow (CBF) rate by using the Langendorff-perfused heart. In the presence of glibenclamide to exclude the effects of ATP-sensitive K + (K ATP) channels, CBF was increased by adenosine (10 μM), which was blocked by the addition of Ba 2+ (50 μM). Above results suggest that adenosine increases K IR current via A 3 subtype through the activation of PKA in rabbit small-diameter coronary arterial smooth muscle cells.

Hyperosmolarity Causes BKCa-Dependent Vasodilatations in Rat Skeletal Muscle Arteries

The release of different metabolites during skeletal muscle contraction causes a pronounced increase in extracellular osmolarity (hyperosmolarity (HO)). HO has been considered as a possible mediator of the exercise hyperemia. In the present study, we investigated the vasodilatory effect of physiologically relevant increases in the extracellular osmolarity in isolated rat gluteal muscle arterioles. In addition, we analyzed the underlying mechanisms of the HO-induced vasodilatations. Rat gluteal arteries were isolated and mounted in an organ bath for isometric tension recording. After precontraction with norepinephrine, 20, 40, or 60 mmol x L(-1) sucrose, mannitol, or urea was added in control conditions, after removal of the endothelium or in the presence of inhibitors. Application of sucrose or mannitol induced large and fast concentration-dependent vasodilatations (up to 46.15% with 60 mmol x L(-1) sucrose). Removal of the vascular endothelium had no effect on this relaxation. Inhibition of the Na+/K+ pumps with ouabain, the Kir IR channels with Ba2+ and the K ATP channels with glibenclamide did not alter the HO-induced relaxations. Incubation with the KCa channel blockers charybdotoxin and apamin significantly inhibited sucrose-induced vasodilatations. In addition, application of the specific BK Ca channel blocker iberiotoxin significantly decreased the HO-induced vasodilatations. The present study shows that an increase in the extracellular osmolarity elicits strong, fast, and long-lasting relaxations of rat skeletal muscle arterioles, suggesting an important role both at the onset and during the steady-state phase of an exercise bout. Vascular smooth muscle BK Ca channels seem to play a crucial role in the HO-induced vasorelaxations.

Identifying the regional thermal‐IR radiative signature of mineral dust with MODIS

We use MODIS Terra Level 1B data containing calibrated and geolocated radiances to investigate a regional signature of wind‐blown mineral dust in the thermal‐IR. MODIS data over oceans for the 2000–2004 time period were examined for the presence of dust plumes that originate from the main dust sources located in East and South Asia, Middle East, Northern Africa, and Australia. A number of representative cases for different source regions were selected and analyzed in terms of brightness temperatures at three IR channels centered at 8.55, 11.03, and 12.02 μm. The distinct differences in the thermal‐IR signature of atmospheric dust for the considered regions were found. Our analysis indicates that these differences are likely due to different mineralogical composition, although other factors (e.g., multilayered vertical distribution) may be also involved. Implications of our findings to the detection of dust based on the techniques using brightness temperature differences are discussed.

Nowcasting of convective cells over Italian Peninsula

Abstract. The aim of the study is the individuation of convective cells over the Italian peninsula with the conjunction use of geostationary satellite data (METEOSAT, MSG satellite) in the IR and WV channels and lightning data. We will use GCD (Global Convective Diagnostic) algorithm developed at Aviation Weather Centre (AWC) of NOAA (National Oceanic and Atmospheric Administration). This algorithm is based on the idea that a deep convective cloud will not have any significant moisture above it. This technique works quite well at identifying active deep convection and can be applied to all the world's geostationary satellites. However it does not always agree with lightning sensors. Low topped convection with lightning will be missed. We will extend the capabilities of GCD using lightning data. The new product will be validate over different cases in the central Italy using the C-band polarimetric radar of ISAC-CNR (Institute of Atmospheric Sciences and Climate-of the Italian National Research Council) Rome.

Two distinct pathways account for EDHF‐dependent dilatation in the gracilis artery of dyslipidaemic hApoB+/+ mice

1 A universal endothelium-derived hyperpolarising factor (EDHF--non-NO/non-PGI(2)) has not been identified. EDHF, however, is essential for the physiological control of resistance artery tone. The impact of dyslipidaemia (DL), a risk factor for cardiovascular diseases, on the nature and the efficacy of EDHF has not been evaluated yet. 2 Pressurised (80 mmHg) gracilis arterial segments isolated from mice expressing the human apoB-100 and C57Bl/6 wild-type (WT) mice were used. EDHF-dependent dilatations to acetylcholine (ACh) were measured in the presence of L-NNA (100 microM, NOS inhibitor) and indomethacin (10 microM, COX inhibitor). 3 Maximal EDHF-induced dilatations were increased in DL when compared to WT (95+/-2 versus 86+/-4% in WT; P<0.05). Combination of apamin and charybdotoxin strongly reduced (P<0.05) ACh-induced dilatation in WT (22+/-4%) and DL (25+/-5%). 4 Combined addition of barium (Ba(2+)) and ouabain abolished EDHF-induced dilatations in WT arteries (13+/-3%; P<0.05). In vessels isolated from DL mice, however, only the addition of 14,15-EEZE (a 14,15-EET antagonist) to Ba(2+) and ouabain prevented EDHF-induced dilatations (5+/-3% compared to 54+/-11% in the presence of combined Ba(2+) and ouabain; P<0.05). 5 Our data suggest that EDHF-mediated dilatation depends on the opening of endothelial SK(Ca) and IK(Ca) channels. This is associated with the opening of K(ir) channels and activation of the Na(+)/K(+)-ATPase pump on smooth muscle cells leading to dilatation. In arteries from DL mice, a cytochrome P450 metabolite likely to be 14,15-EET equally contributes to the dilatory action of ACh. The early increased efficacy of EDHF in arteries isolated from DL mice may originate from the duplication of the EDHF pathways.

Recent Innovations in Deriving Tropospheric Winds from Meteorological Satellites

The evolving constellation of environmental/meteorological satellites and their associated sensor technology is rapidly advancing. This is providing opportunities for creatively improving satellite-derived products used in weather analysis and forecasting. For example, the retrieval methods for deriving atmospheric motion vectors (AMVs) from satellites have been expanding and evolving since the early 1970s. Contemporary AMV processing methods are continuously being updated and advanced through the exploitation of new sensor technologies and innovative new approaches. It is incumbent upon the research community working in AMV extraction techniques to ensure that the quality of the current operational products meets or exceeds the needs of the user community. In particular, the advances in data assimilation and numerical weather prediction in recent years have placed an increasing demand on data quality. To keep pace with these demands, innovative research toward improving methods of deriving winds from satellites has been a focus of the World Meteorological Organization and Coordination Group for Meteorological Satellites (CGMS) cosponsored International Winds Workshops (IWWs). The IWWs are held every 2 yr, and bring together AMV researchers from around the world to present new ideas on AMV extraction techniques, interpretation, and applications. The NWP community is always well represented at these workshops, which provide an important exchange of information on the latest in data assimilation issues. This article draws from recent IWWs, and describes several new advances in satellite-produced wind technologies, derivation methodologies, and products. Examples include AMVs derived from Geostationary Operational Environmental Satellite (GOES) rapid scans and the shortwave IR channel, AMVs over the polar regions from the Moderate Resolution Imaging Spectroradiometer (MODIS), improved AMV products from the new Meteosat Second Generation satellite, and new processing approaches for deriving AMVs. The article also provides a glimpse into the pending opportunities that will be afforded with emerging/anticipated new sensor technologies.

A LEGO-based control experiment

A nice feature of the LEGO system is that, although the mechanical, electrical, and structural construction is good enough for successful results, there are enough discrepancies between theory and practice to introduce the student to real-world problems of controller. This article concentrates on implementing the feedback controller within the RCX, with the host computer used for compiling, downloading, and data display. However, an interesting research project is to implement part of the controller on the host computer and communicate by means of the IR channel. The bandwidth restriction that this approach imposes can provide the basis for a research project on control through a restricted bandwidth channel.