Pre-Flight Calibration of the Mars 2020 Rover Mastcam Zoom (Mastcam-Z) Multispectral, Stereoscopic Imager.

The NASA Perseverance rover Mast Camera Zoom (Mastcam-Z) system is a pair of zoomable, focusable, multi-spectral, and color charge-coupled device (CCD) cameras mounted on top of a 1.7 m Remote Sensing Mast, along with associated electronics and two calibration targets. The cameras contain identical optical assemblies that can range in focal length from 26 mm ( 25.5 ∘ × 19.1 ∘ FOV ) to 110 mm ( 6.2 ∘ × 4.2 ∘ FOV ) and will acquire data at pixel scales of 148-540 µm at a range of 2 m and 7.4-27 cm at 1 km. The cameras are mounted on the rover's mast with a stereo baseline of 24.3 ± 0.1  cm and a toe-in angle of 1.17 ± 0.03 ∘ (per camera). Each camera uses a Kodak KAI-2020 CCD with 1600 × 1200 active pixels and an 8 position filter wheel that contains an IR-cutoff filter for color imaging through the detectors' Bayer-pattern filters, a neutral density (ND) solar filter for imaging the sun, and 6 narrow-band geology filters (16 total filters). An associated Digital Electronics Assembly provides command data interfaces to the rover, 11-to-8 bit companding, and JPEG compression capabilities. Herein, we describe pre-flight calibration of the Mastcam-Z instrument and characterize its radiometric and geometric behavior. Between April 26 t h and May 9 t h , 2019, ∼45,000 images were acquired during stand-alone calibration at Malin Space Science Systems (MSSS) in San Diego, CA. Additional data were acquired during Assembly Test and Launch Operations (ATLO) at the Jet Propulsion Laboratory and Kennedy Space Center. Results of the radiometric calibration validate a 5% absolute radiometric accuracy when using camera state parameters investigated during testing. When observing using camera state parameters not interrogated during calibration (e.g., non-canonical zoom positions), we conservatively estimate the absolute uncertainty to be < 10 % . Image quality, measured via the amplitude of the Modulation Transfer Function (MTF) at Nyquist sampling (0.35 line pairs per pixel), shows MTF Nyquist = 0.26 - 0.50 across all zoom, focus, and filter positions, exceeding the > 0.2 design requirement. We discuss lessons learned from calibration and suggest tactical strategies that will optimize the quality of science data acquired during operation at Mars. While most results matched expectations, some surprises were discovered, such as a strong wavelength and temperature dependence on the radiometric coefficients and a scene-dependent dynamic component to the zero-exposure bias frames. Calibration results and derived accuracies were validated using a Geoboard target consisting of well-characterized geologic samples. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s11214-021-00795-x.

The Mars 2020 Perseverance Rover Mast Camera Zoom (Mastcam-Z) Multispectral, Stereoscopic Imaging Investigation.

Mastcam-Z is a multispectral, stereoscopic imaging investigation on the Mars 2020 mission's Perseverance rover. Mastcam-Z consists of a pair of focusable, 4:1 zoomable cameras that provide broadband red/green/blue and narrowband 400-1000 nm color imaging with fields of view from 25.6° × 19.2° (26 mm focal length at 283 µrad/pixel) to 6.2° × 4.6° (110 mm focal length at 67.4 µrad/pixel). The cameras can resolve (≥ 5 pixels) ∼0.7 mm features at 2 m and ∼3.3 cm features at 100 m distance. Mastcam-Z shares significant heritage with the Mastcam instruments on the Mars Science Laboratory Curiosity rover. Each Mastcam-Z camera consists of zoom, focus, and filter wheel mechanisms and a 1648 × 1214 pixel charge-coupled device detector and electronics. The two Mastcam-Z cameras are mounted with a 24.4 cm stereo baseline and 2.3° total toe-in on a camera plate ∼2 m above the surface on the rover's Remote Sensing Mast, which provides azimuth and elevation actuation. A separate digital electronics assembly inside the rover provides power, data processing and storage, and the interface to the rover computer. Primary and secondary Mastcam-Z calibration targets mounted on the rover top deck enable tactical reflectance calibration. Mastcam-Z multispectral, stereo, and panoramic images will be used to provide detailed morphology, topography, and geologic context along the rover's traverse; constrain mineralogic, photometric, and physical properties of surface materials; monitor and characterize atmospheric and astronomical phenomena; and document the rover's sample extraction and caching locations. Mastcam-Z images will also provide key engineering information to support sample selection and other rover driving and tool/instrument operations decisions.

The Mars 2020 Engineering Cameras and Microphone on the Perseverance Rover: A Next-Generation Imaging System for Mars Exploration.

The Mars 2020 Perseverance rover is equipped with a next-generation engineering camera imaging system that represents an upgrade over previous Mars rover missions. These upgrades will improve the operational capabilities of the rover with an emphasis on drive planning, robotic arm operation, instrument operations, sample caching activities, and documentation of key events during entry, descent, and landing (EDL). There are a total of 16 cameras in the Perseverance engineering imaging system, including 9 cameras for surface operations and 7 cameras for EDL documentation. There are 3 types of cameras designed for surface operations: Navigation cameras (Navcams, quantity 2), Hazard Avoidance Cameras (Hazcams, quantity 6), and Cachecam (quantity 1). The Navcams will acquire color stereo images of the surface with a 96 ∘ × 73 ∘ field of view at 0.33 mrad/pixel. The Hazcams will acquire color stereo images of the surface with a 136 ∘ × 102 ∘ at 0.46 mrad/pixel. The Cachecam, a new camera type, will acquire images of Martian material inside the sample tubes during caching operations at a spatial scale of 12.5 microns/pixel. There are 5 types of EDL documentation cameras: The Parachute Uplook Cameras (PUCs, quantity 3), the Descent stage Downlook Camera (DDC, quantity 1), the Rover Uplook Camera (RUC, quantity 1), the Rover Descent Camera (RDC, quantity 1), and the Lander Vision System (LVS) Camera (LCAM, quantity 1). The PUCs are mounted on the parachute support structure and will acquire video of the parachute deployment event as part of a system to characterize parachute performance. The DDC is attached to the descent stage and pointed downward, it will characterize vehicle dynamics by capturing video of the rover as it descends from the skycrane. The rover-mounted RUC, attached to the rover and looking upward, will capture similar video of the skycrane from the vantage point of the rover and will also acquire video of the descent stage flyaway event. The RDC, attached to the rover and looking downward, will document plume dynamics by imaging the Martian surface before, during, and after rover touchdown. The LCAM, mounted to the bottom of the rover chassis and pointed downward, will acquire 90 ∘ × 90 ∘ FOV images during the parachute descent phase of EDL as input to an onboard map localization by the Lander Vision System (LVS). The rover also carries a microphone, mounted externally on the rover chassis, to capture acoustic signatures during and after EDL. The Perseverance rover launched from Earth on July 30th, 2020, and touchdown on Mars is scheduled for February 18th, 2021.

Location and Setting of the Mars InSight Lander, Instruments, and Landing Site.

Knowing precisely where a spacecraft lands on Mars is important for understanding the regional and local context, setting, and the offset between the inertial and cartographic frames. For the InSight spacecraft, the payload of geophysical and environmental sensors also particularly benefits from knowing exactly where the instruments are located. A ~30 cm/pixel image acquired from orbit after landing clearly resolves the lander and the large circular solar panels. This image was carefully georeferenced to a hierarchically generated and coregistered set of decreasing resolution orthoimages and digital elevation models to the established positive east, planetocentric coordinate system. The lander is located at 4.502384°N, 135.623447°E at an elevation of -2,613.426 m with respect to the geoid in Elysium Planitia. Instrument locations (and the magnetometer orientation) are derived by transforming from Instrument Deployment Arm, spacecraft mechanical, and site frames into the cartographic frame. A viewshed created from 1.5 m above the lander and the high-resolution orbital digital elevation model shows the lander is on a shallow regional slope down to the east that reveals crater rims on the east horizon ~400 m and 2.4 km away. A slope up to the north limits the horizon to about 50 m away where three rocks and an eolian bedform are visible on the rim of a degraded crater rim. Azimuths to rocks and craters identified in both surface panoramas and high-resolution orbital images reveal that north in the site frame and the cartographic frame are the same (within 1°).

Geology of the InSight landing site on Mars.

The Interior Exploration using Seismic Investigations, Geodesy and Heat Transport (InSight) spacecraft landed successfully on Mars and imaged the surface to characterize the surficial geology. Here we report on the geology and subsurface structure of the landing site to aid in situ geophysical investigations. InSight landed in a degraded impact crater in Elysium Planitia on a smooth sandy, granule- and pebble-rich surface with few rocks. Superposed impact craters are common and eolian bedforms are sparse. During landing, pulsed retrorockets modified the surface to reveal a near surface stratigraphy of surficial dust, over thin unconsolidated sand, underlain by a variable thickness duricrust, with poorly sorted, unconsolidated sand with rocks beneath. Impact, eolian, and mass wasting processes have dominantly modified the surface. Surface observations are consistent with expectations made from remote sensing data prior to landing indicating a surface composed of an impact-fragmented regolith overlying basaltic lava flows.

Martian fluvial conglomerates at Gale crater.

Observations by the Mars Science Laboratory Mast Camera (Mastcam) in Gale crater reveal isolated outcrops of cemented pebbles (2 to 40 millimeters in diameter) and sand grains with textures typical of fluvial sedimentary conglomerates. Rounded pebbles in the conglomerates indicate substantial fluvial abrasion. ChemCam emission spectra at one outcrop show a predominantly feldspathic composition, consistent with minimal aqueous alteration of sediments. Sediment was mobilized in ancient water flows that likely exceeded the threshold conditions (depth 0.03 to 0.9 meter, average velocity 0.20 to 0.75 meter per second) required to transport the pebbles. Climate conditions at the time sediment was transported must have differed substantially from the cold, hyper-arid modern environment to permit aqueous flows across several kilometers.

Local recurrence of rectal cancer in patients not receiving neoadjuvant therapy - the importance of resection margins.

OBJECTIVES: Local recurrence of rectal cancer reduces quality of life and survival. A multi-factorial linear logistic model was used to analyse risk factors for local recurrence in rectal cancer in patients not receiving preoperative chemo-radiation. METHODS: A case-control study of patients with rectal cancer having surgery with curative intent, between 1996 and 2008. Eighteen putative risk factors for local recurrence were subjected to uni-variate analysis. Significant factors were selected for multi-factorial analysis. RESULTS: Twenty-one patients with local recurrence (cases) and 78 controls were selected. Uni-variate analysis showed significant associations with recurrence for nodal stage (N) (p=0.027), metastasis (M) (p=0.009), adjuvant chemotherapy (p=0.039), positive resection margin (R) (p=0.018) and American Joint Committee for Cancer (AJCC) tumours above stage II (p=0.043). Significant uni-variate odds ratios (OR) were obtained for the same factors. Two linear logistic models were fitted as (1) N, M, R1 status and adjuvant chemotherapy and (2) AJCC stage, R1 status and adjuvant chemotherapy. From both models, the only factor significantly associated (p ≤ 0.01) with local recurrence was found to be a positive resection margin (OR 4.81 and 5.51 respectively). CONCLUSIONS: A positive resection margin is the single factor affecting local recurrence of rectal cancer in patients not receiving neo-adjuvant therapy.

Levels of interleukins 12 (IL-12) and 13 (IL-13), hepatitis B and C serology, and blood cultures among acute myeloid leukemia (AML) patients in Egypt

There is an interest in the use of IL-12 as a possible anti-cancer drug to induce immune responses and anti-IL-13 formulations to treat the undesirable effects of IL-13. Thus, the present study aimed at analyzing IL-12 and IL-13 profiles, viral hepatitis serology and blood cultures in acute myeloid leukemia (AML) patients. Forty individuals (20 without septicemia - Group A, and 20 with septicemia - Group B) and 20 healthy controls were evaluated. Hepatitis B virus antigens (HBsAg) and hepatitis C virus antibodies (HCV Ab) were quantified using commercial ELISA kits. IL-12 and IL-13 levels were estimated in culture supernatant of mitogen-stimulated peripheral blood mononuclear cells by ELISA. Significantly low IL-12 values were observed among AML patients compared to controls whereas the opposite was observed regarding IL-13. IL-12 levels were found to be elevated in the follow-up cases. M4 and M5 subtypes of AML presented higher IL-12 levels than M1 and M2 subtypes. The isolated organisms from AML with septicemia were Staphylococcus aureus (35 percent), Esherichia coli (25 percent), coagulase-negative staphylococci (25 percent), and Candida (15 percent). Fungemia cases showed higher IL-12 values than bacteremia cases. In conclusion, IL-12 and IL-13 should be further tested in large-scale studies to provide future immunotherapy against AML.(AU)

Young patients with colorectal cancer have poor survival in the first twenty months after operation and predictable survival in the medium and long-term: analysis of survival and prognostic markers.

OBJECTIVES: This study compares clinico-pathological features in young (<40 years) and older patients (>50 years) with colorectal cancer, survival in the young and the influence of pre-operative clinical and histological factors on survival. MATERIALS AND METHODS: A twelve year prospective database of colorectal cancer was analysed. Fifty-three young patients were compared with forty seven consecutive older patients over fifty years old. An analysis of survival was undertaken in young patients using Kaplan Meier graphs, non parametric methods, Cox's Proportional Hazard Ratios and Weibull Hazard models. RESULTS: Young patients comprised 13.4 percent of 397 with colorectal cancer. Duration of symptoms and presentation in the young was similar to older patients (median, range; young patients; 6 months, 2 weeks to 2 years, older patients; 4 months, 4 weeks to 3 years, p > 0.05). In both groups, the majority presented without bowel obstruction (young--81%, older--94%). Cancer proximal to the splenic flexure was present more in young than in older patients. Synchronous cancers were found exclusively in the young. Mucinous tumours were seen in 16% of young and 4% of older patients (p < 0.05). Ninety four percent of young cancer deaths were within 20 months of operation. At median follow up of 50 months in the young, overall survival was 70% and disease free survival 66%. American Joint Committee on Cancer (AJCC) stage 4 and use of pre-operative chemoradiation in rectal cancer was associated with poor survival in the young. CONCLUSION: If patients, who are less than 40 years old with colorectal cancer, survive twenty months after operation, the prognosis improves and their survival becomes predictable.

Chemical accumulation and voltammetric determination of traces of nickel(II) at glassy carbon electrodes modified with dimethyl glyoxime containing polymer coatings.

The objective of the present study was to develop a solid mercury free electrode for the voltammetric determination of traces of nickel(II) in solution. For this purpose chemically modified electrodes (CME's) were constructed from glassy carbon coated with dimethylglyoxime-containing polymers. CME's based on a composite matrix, which contained polyvinyl chloride, polyaniline, and dimethylglyoxime were shown to possess the ability to accumulate traces of nickel(II) from ammonia buffered aquatic solutions by a purely chemical attachment. Moreover the nickel(II) contents of such solutions could be determined using voltammetric quantitation of the nickel(II) dimethylglyoximate deposits on the CME surfaces and the standard addition technique. The CME surfaces could subsequently be regenerated by acid treatment. The limit of detection for Ni(II) following a 240 s chemical deposition was estimated as 18 mug Ni l(-1), and the CME results for traces of Ni(II) in fresh water compared well with the results obtained by atomic absorption spectroscopy. Moreover the CME's retained their sensitivity for more than two days, i.e. significantly longer than the 3 h, during which analogous carbon paste electrodes completely lost their affinity to nickel(II).

New directions in materials management ... dialog.

Today, the VHA stands as the country's largest hospital purchasing program, representing hospitals that purchase over $1.5 billion in supplies each year. But not all of that comes through VHA programs, and it is in the relationship between the individual institutions and the VHA system, that the group draws its strength and discovers its limitations. At once highly sophisticated and fiercely independent, the materials managers that make up the VHA program must weigh the significant opportunities inherent in the group's size and scope against the individual demands of their institutions. Mutual understanding leads to consensus and eventually to commitment and out of that process comes a number of highly innovative programs, such as standardization and single sourcing and the VHA Plus private label program, that are helping to make the VHA not simply the country's leading purchasing organization, but its most innovative as well--a true materials management system.

Contaminated roof-collected rainwater as a possible cause of an outbreak of salmonellosis.

Roof-collected rainwater is a common water source in subtropical regions and has not been associated with human illness. In Trinidad, the West Indies, a church group, attending a rural camp, developed gastrointestinal illness, caused by Salmonella arechevalata. This rare serotype was isolated from stool specimens of campers, foods eaten at the camp, and a water tap, which was supplied by a storage tank of roof-collected rainwater. The surface of the roof, used as water catchment, was covered with bird faeces. It is postulated that rainwater, falling on the roof, washed off animal excrement which contained S. arechevalata and led to the outbreak of salmonellosis through camper ingestion of contaminated food and water.

Yellow Fever in Trinidad & Tobago 1978-1980: epidemiological aspects

Between 1978-1979 an epidemic of yellow fever occured in Trinidad in two phases. Eight cases occurred in December 1978-March 1979 and 10 cases occurred in August-September 1979. Seven died, giving a case fatality rate of 39 percent. All cases were male aged 16-58 years (median 22.5). Seventeen had been exposed in forests where the virus was active and none had records of being vaccinated. The high level of clinical and virological surveillance that existed made it likely that all or nearly all the cases were ascertained. Intense immunization, health education and vector control efforts also mitigated against a larger epidemic (AU)