Thermal Infrared Imaging Experiments of C-Type Asteroid 162173 Ryugu on Hayabusa2

The thermal infrared imager TIR onboard Hayabusa2 has been developed to investigate thermo-physical properties of C-type, near-Earth asteroid 162173 Ryugu. TIR is one of the remote science instruments on Hayabusa2 designed to understand the nature of a volatile-rich solar system small body, but it also has significant mission objectives to provide information on surface physical properties and conditions for sampling site selection as well as the assessment of safe landing operations. TIR is based on a two-dimensional uncooled micro-bolometer array inherited from the Longwave Infrared Camera LIR on Akatsuki (Fukuhara et al., 2011). TIR takes images of thermal infrared emission in 8 to 12 μm with a field of view of 16×12∘ and a spatial resolution of 0.05∘ per pixel. TIR covers the temperature range from 150 to 460 K, including the well calibrated range from 230 to 420 K. Temperature accuracy is within 2 K or better for summed images, and the relative accuracy or noise equivalent temperature difference (NETD) at each of pixels is 0.4 K or lower for the well-calibrated temperature range. TIR takes a couple of images with shutter open and closed, the corresponding dark frame, and provides a true thermal image by dark frame subtraction. Data processing involves summation of multiple images, image processing including the StarPixel compression (Hihara et al., 2014), and transfer to the data recorder in the spacecraft digital electronics (DE). We report the scientific and mission objectives of TIR, the requirements and constraints for the instrument specifications, the designed instrumentation and the pre-flight and in-flight performances of TIR, as well as its observation plan during the Hayabusa2 mission

An exploration of feature detector performance in the thermal-infrared modality

Thermal-infrared images have superior statistical properties compared with visible-spectrum images in many low-light or no-light scenarios. However, a detailed understanding of feature detector performance in the thermal modality lags behind that of the visible modality. To address this, the first comprehensive study on feature detector performance on thermal-infrared images is conducted. A dataset is presented which explores a total of ten different environments with a range of statistical properties. An investigation is conducted into the effects of several digital and physical image transformations on detector repeatability in these environments. The effect of non-uniformity noise, unique to the thermal modality, is analyzed. The accumulation of sensor non-uniformities beyond the minimum possible level was found to have only a small negative effect. A limiting of feature counts was found to improve the repeatability performance of several detectors. Most other image transformations had predictable effects on feature stability. The best-performing detector varied considerably depending on the nature of the scene and the test

Nitric oxide donation lowers blood pressure in adrenocorticotrophic hormone-induced hypertensive rats.

Adrenocorticotrophic hormone (ACTH) elevates systolic blood pressure (SBP) and lowers plasma reactive nitrogen intermediates in rats. We assessed the ability of NO donation from isosorbide dinitrate (ISDN) to prevent or reverse the hypertension caused by ACTH. In the prevention study, male Sprague Dawley rats were treated with ACTH (0.2 mg/kg/day) or saline control for 8 days, with either concurrent ISDN (100 mg/kg/day) via the drinking water or water alone. Animals receiving ISDN via the drinking water were provided with nitrate-free water for 8 hours every day. In the reversal study ISDN (100 mg/kg) or vehicle was given as a single oral dose on day 8. SBP was measured daily by the indirect tail-cuff method in conscious, restrained rats. ACTH caused a significant increase in SBP compared with saline (P < 0.0015). In the prevention study, chronic administration of ISDN (100 mg/kg/day) did not affect the SBP in either group. In the reversal study, ISDN significantly lowered SBP in ACTH-treated rats at 1 and 2.5 hours (132 +/- 3 mmHg (1 h) and 131 +/- 2 mmHg (2.5 h) versus 143 +/- 3 mmHg (0 h), P < 0.002), but not to control levels. It had no effect in control (saline treated) rats. In conclusion, the lowering of SBP by NO donation is consistent with the notion that ACTH-induced hypertension involves an impaired bioavailability or action of NO in vivo

Lithologic mapping of silicate rocks using TIMS

Common rock-forming minerals have thermal infrared spectral features that are measured in the laboratory to infer composition. An airborne Daedalus scanner (TIMS) that collects six channels of thermal infrared radiance data (8 to 12 microns), may be used to measure these same features for rock identification. Previously, false-color composite pictures made from channels 1, 3, and 5 and emittance spectra for small areas on these images were used to make lithologic maps. Central wavelength, standard deviation, and amplitude of normal curves regressed on the emittance spectra are related to compositional information for crystalline igneous silicate rocks. As expected, the central wavelength varies systematically with silica content and with modal quartz content. Standard deviation is less sensitive to compositional changes, but large values may result from mixed admixture of vegetation. Compression of the six TIMS channels to three image channels made from the regressed parameters may be effective in improving geologic mapping from TIMS data, and these synthetic images may form a basis for the remote assessment of rock composition

Verbesserung der Wundheilung durch wassergefiltertes Infrarot A (wIRA) bei Patienten mit chronischen venösen Unterschenkel-Ulzera einschließlich infrarot-thermographischer Beurteilung

Background: Water-filtered infrared-A (wIRA) is a special form of heat radiation with a high tissue-penetration and with a low thermal burden to the surface of the skin. wIRA is able to improve essential and energetically meaningful factors of wound healing by thermal and non-thermal effects. Aim of the study: prospective study (primarily planned randomised, controlled, blinded, de facto with one exception only one cohort possible) using wIRA in the treatment of patients with recalcitrant chronic venous stasis ulcers of the lower legs with thermographic follow-up. Methods: 10 patients (5 males, 5 females, median age 62 years) with 11 recalcitrant chronic venous stasis ulcers of the lower legs were treated with water-filtered infrared-A and visible light irradiation (wIRA(+VIS), Hydrosun® radiator type 501, 10 mm water cuvette, water-filtered spectrum 550–1400 nm) or visible light irradiation (VIS; only possible in one patient). The uncovered wounds of the patients were irradiated two to five times per week for 30 minutes at a standard distance of 25 cm (approximately 140 mW/cm2 wIRA and approximately 45 mW/cm2 VIS). Treatment continued for a period of up to 2 months (typically until closure or nearly closure of the ulcer). The main variable of interest was “percent change of ulcer size over time” including complete wound closure. Additional variables of interest were thermographic image analysis, patient’s feeling of pain in the wound, amount of pain medication, assessment of the effect of the irradiation (by patient and by clinical investigator), assessment of feeling of the wound area (by patient), assessment of wound healing (by clinical investigator) and assessment of the cosmetic state (by patient and by clinical investigator). For these assessments visual analogue scales (VAS) were used. Results: The study showed a complete or nearly complete healing of lower leg ulcers in 7 patients and a clear reduction of ulcer size in another 2 of 10 patients, a clear reduction of pain and pain medication consumption (e.g. from 15 to 0 pain tablets per day), and a normalization of the thermographic image (before the beginning of the therapy typically hyperthermic rim of the ulcer with relative hypothermic ulcer base, up to 4.5°C temperature difference). In one patient the therapy of an ulcer of one leg was performed with the fully active radiator (wIRA(+VIS)), while the therapy of an ulcer of the other leg was made with a control group radiator (only VIS without wIRA), showing a clear difference in favour of the wIRA treatment. All mentioned VAS ratings improved remarkably during the period of irradiation treatment, representing an increased quality of life. Failures of complete or nearly complete wound healing were seen only in patients with arterial insufficiency, in smokers or in patients who did not have venous compression garment therapy. Discussion and conclusions: wIRA can alleviate pain considerably (with an impressive decrease of the consumption of analgesics) and accelerate wound healing or improve a stagnating wound healing process and diminish an elevated wound exudation and inflammation both in acute and in chronic wounds (in this study shown in chronic venous stasis ulcers of the lower legs) and in problem wounds including infected wounds. In chronic recalcitrant wounds complete healing is achieved, which was not reached before. Other studies have shown that even without a disturbance of wound healing an acute wound healing process can be improved (e.g. reduced pain) by wIRA. wIRA is a contact-free, easily used and pleasantly felt procedure without consumption of material with a good penetration effect, which is similar to solar heat radiation on the surface of the earth in moderate climatic zones. Wound healing and infection defence (e.g. granulocyte function including antibacterial oxygen radical formation of the granulocytes) are critically dependent on a sufficient energy supply (and on sufficient oxygen). The good clinical effect of wIRA on wounds and also on problem wounds and wound infections can be explained by the improvement of both the energy supply and the oxygen supply (e.g. for the granulocyte function). wIRA causes as a thermal effect in the tissue an improvement in three decisive factors: tissue oxygen partial pressure, tissue temperature and tissue blood flow. Besides this non-thermal effects of infrared-A by direct stimulation of cells and cellular structures with reactions of the cells have also been described. It is concluded that wIRA can be used to improve wound healing, to reduce pain, exudation, and inflammation and to increase quality of life.Hintergrund: Wassergefiltertes Infrarot A (wIRA) ist eine spezielle Form der Wärmestrahlung mit hoher Gewebepenetration bei geringer thermischer Oberflächenbelastung. wIRA vermag über thermische und nicht-thermische Effekte wesentliche und energetisch bedeutsame Faktoren der Wundheilung zu verbessern. Ziel der Studie: prospektive Studie (primär randomisiert, kontrolliert, verblindet geplant, de facto mit einer Ausnahme nur eine Kohorte möglich) mit wassergefiltertem Infrarot A (wIRA) in der Therapie von Patienten mit therapierefraktären chronischen venösen Unterschenkel-Ulzera mit thermographischer Verlaufskontrolle. Methoden: 10 Patienten (5 Männer, 5 Frauen, Median des Alters 62 Jahre) mit 11 therapierefraktären chronischen venösen Unterschenkel-Ulzera wurden mit wassergefiltertem Infrarot A und sichtbarem Licht (wIRA(+VIS), Hydrosun®-Strahler Typ 501, 10 mm Wasserküvette, wassergefiltertes Spektrum 550–1400 nm) oder mit sichtbarem Licht (VIS; nur bei einem Patienten möglich) bestrahlt. Die unbedeckten Wunden der Patienten wurden zwei- bis fünfmal pro Woche über bis zu 2 Monate (typischerweise bis zum Wundschluss oder Fast-Wundschluss des Ulkus) für jeweils 30 Minuten mit einem Standardabstand von 25 cm bestrahlt (ungefähr 140 mW/cm2 wIRA und ungefähr 45 mW/cm2 VIS). Hauptzielvariable war die „prozentuale Änderung der Ulkusgröße über die Zeit“ einschließlich des kompletten Wundschlusses. Zusätzliche Zielvariablen waren thermographische Bildanalyse, Schmerzempfinden des Patienten in der Wunde, Schmerzmittelverbrauch, Einschätzung des Effekts der Bestrahlung (durch Patient und durch klinischen Untersucher), Einschätzung des Patienten des Gefühls im Wundbereich, Einschätzung der Wundheilung durch den klinischen Untersucher sowie Einschätzung des kosmetischen Zustandes (durch Patienten und durch klinischen Untersucher). Für diese Erhebungen wurden visuelle Analogskalen (VAS) verwendet. Ergebnisse: Die Studie ergab eine vollständige oder fast vollständige Abheilung der Unterschenkel-Ulzera bei 7 Patienten sowie eine deutliche Ulkusverkleinerung bei 2 weiteren der 10 Patienten, eine bemerkenswerte Minderung der Schmerzen und des Schmerzmittelverbrauchs (von z.B. 15 auf 0 Schmerztabletten täglich) und eine Normalisierung des thermographischen Bildes (vor Therapiebeginn typischerweise hyperthermer Ulkusrandwall mit relativ hypothermem Ulkusgrund, bis zu 4,5°C Temperaturdifferenz). Bei einem Patienten wurde ein Ulkus an einem Bein mit dem Vollwirkstrahler (wIRA(+VIS)) therapiert, während ein Ulkus am anderen Bein mit einem Kontrollgruppenstrahler (nur VIS, ohne wIRA) behandelt wurde, was einen deutlichen Unterschied zugunsten der wIRA-Therapie zeigte. Alle aufgeführten VAS-Einschätzungen verbesserten sich während der Bestrahlungstherapie-Periode sehr stark, was einer verbesserten Lebensqualität entsprach. Ein kompletter oder fast kompletter Wundschluss wurde nur bei Patienten mit peripherer arterieller Verschlusskrankheit, Rauchern oder Patienten mit fehlender venöser Kompressionstherapie nicht erreicht. Diskussion und Schlussfolgerungen: wIRA kann sowohl bei akuten Wunden als auch bei chronischen Wunden (in dieser Studie für chronische venöse Unterschenkelulzera gezeigt) und Problemwunden einschließlich infizierter Wunden Schmerzen deutlich mindern (mit eindrucksvoller Abnahme des Schmerzmittelverbrauchs) und die Wundheilung beschleunigen oder einen stagnierenden Wundheilungsprozess verbessern sowie eine erhöhte Wundsekretion und Entzündung mindern. Bei chronischen therapierefraktären Wunden werden vollständige Abheilungen erreicht, die zuvor nicht erreicht wurden. Andere Studien haben sogar ohne Wundheilungsstörung eine Verbesserung (z.B. Schmerzreduktion) der akuten Wundheilung durch wIRA gezeigt. wIRA ist ein kontaktfreies, verbrauchsmaterialfreies, leicht anzuwendendes, als angenehm empfundenes Verfahren mit guter Tiefenwirkung, das der Sonnenwärmestrahlung auf der Erdoberfläche in gemäßigten Klimazonen nachempfunden ist. Wundheilung und Infektionsabwehr (z.B. Granulozytenfunktion einschließlich antibakterieller Sauerstoffradikalbildung der Granulozyten) hängen ganz entscheidend von einer ausreichenden Energieversorgung (und von ausreichend Sauerstoff) ab. Die gute klinische Wirkung von wIRA auf Wunden und auch auf Problemwunden und Wundinfektionen lässt sich über die Verbesserung sowohl der Energiebereitstellung als auch der Sauerstoffversorgung (z.B. für die Granulozytenfunktion) erklären. wIRA bewirkt als thermischen Effekt im Gewebe eine Verbesserung von drei entscheidenden Faktoren: Sauerstoffpartialdruck im Gewebe, Gewebetemperatur und Gewebedurchblutung. Daneben wurden auch nicht-thermische Effekte von Infrarot A durch direkte Reizsetzung auf Zellen und zelluläre Strukturen mit Reaktionen der Zellen beschrieben. Es wird geschlossen, dass wIRA verwendet werden kann, um Wundheilung zu verbessern, Schmerzen, Sekretion und Entzündung zu reduzieren und die Lebensqualität zu steigern

Simultaneous real-time visible and infrared video with single-pixel detectors

Conventional cameras rely upon a pixelated sensor to provide spatial resolution. An alternative approach replaces the sensor with a pixelated transmission mask encoded with a series of binary patterns. Combining knowledge of the series of patterns and the associated filtered intensities, measured by single-pixel detectors, allows an image to be deduced through data inversion. In this work we extend the concept of a ‘single-pixel camera’ to provide continuous real-time video at 10 Hz , simultaneously in the visible and short-wave infrared, using an efficient computer algorithm. We demonstrate our camera for imaging through smoke, through a tinted screen, whilst performing compressive sampling and recovering high-resolution detail by arbitrarily controlling the pixel-binning of the masks. We anticipate real-time single-pixel video cameras to have considerable importance where pixelated sensors are limited, allowing for low-cost, non-visible imaging systems in applications such as night-vision, gas sensing and medical diagnostics

Time frequency analysis in terahertz pulsed imaging

Recent advances in laser and electro-optical technologies have made the previously under-utilized terahertz frequency band of the electromagnetic spectrum accessible for practical imaging. Applications are emerging, notably in the biomedical domain. In this chapter the technique of terahertz pulsed imaging is introduced in some detail. The need for special computer vision methods, which arises from the use of pulses of radiation and the acquisition of a time series at each pixel, is described. The nature of the data is a challenge since we are interested not only in the frequency composition of the pulses, but also how these differ for different parts of the pulse. Conventional and short-time Fourier transforms and wavelets were used in preliminary experiments on the analysis of terahertz pulsed imaging data. Measurements of refractive index and absorption coefficient were compared, wavelet compression assessed and image classification by multidimensional clustering techniques demonstrated. It is shown that the timefrequency methods perform as well as conventional analysis for determining material properties. Wavelet compression gave results that were robust through compressions that used only 20% of the wavelet coefficients. It is concluded that the time-frequency methods hold great promise for optimizing the extraction of the spectroscopic information contained in each terahertz pulse, for the analysis of more complex signals comprising multiple pulses or from recently introduced acquisition techniques