Hexagonal Prisms Form in Water-Ice Clouds on Mars, Producing Halo Displays Seen by Perseverance Rover.

Observations by several cameras on the Perseverance rover showed a 22° scattering halo around the Sun over several hours during northern midsummer (solar longitude 142°). Such a halo has not previously been seen beyond Earth. The halo occurred during the aphelion cloud belt season and the cloudiest time yet observed from the Perseverance site. The halo required crystalline water-ice cloud particles in the form of hexagonal columns large enough for refraction to be significant, at least 11 µm in diameter and length. From a possible 40-50 km altitude, and over the 3.3 hr duration of the halo, particles could have fallen 3-12 km, causing downward transport of water and dust. Halo-forming clouds are likely rare due to the high supersaturation of water that is required but may be more common in northern subtropical regions during northern midsummer.

Demographic and HIV-specific characteristics of participants enrolled in the INSIGHT Strategic Timing of AntiRetroviral Treatment (START) trial.

OBJECTIVES: The risks and benefits of initiating antiretroviral treatment (ART) at high CD4 cell counts have not been reliably quantified. The Strategic Timing of AntiRetroviral Treatment (START) study is a randomized international clinical trial that compares immediate with deferred initiation of ART for HIV-positive individuals with CD4 cell counts above 500 cells/µL. We describe the demographics, HIV-specific characteristics and medical history of this cohort. METHODS: Data collected at baseline include demographics, HIV-specific laboratory values, prior medical diagnoses and concomitant medications. Baseline characteristics were compared by geographical region, gender and age. RESULTS: START enrolled 4685 HIV-positive participants from 215 sites in 35 countries. The median age is 36 years [interquartile range (IQR) 29-44 years], 27% are female, and 45% self-identify as white, 30% as black, 14% as Latino/Hispanic, 8% as Asian and 3% as other. The route of HIV acquisition is reported as men who have sex with men in 55% of participants, heterosexual sex in 38%, injecting drug use in 1% and other/unknown in 5%. Median time since HIV diagnosis is 1.0 year (IQR 0.4-3.0 years) and the median CD4 cell count and HIV RNA values at study entry are 651 cells/µL (IQR 584-765 cells/µL) and 12,754 HIV RNA copies/mL (IQR 3014-43,607 copies/mL), respectively. CONCLUSIONS: START has enrolled a diverse group of ART-naïve individuals with high CD4 cell counts who are comparable to the HIV-positive population from the regions in which they were enrolled. The information collected with this robust study design will provide a database with which to evaluate the risks and benefits of early ART use for many important outcomes.

Quality of life assessment among HIV-positive persons entering the INSIGHT Strategic Timing of AntiRetroviral Treatment (START) trial.

OBJECTIVES: With HIV treatment prolonging survival and HIV infection now managed as a chronic illness, quality of life (QOL) is important to evaluate in persons living with HIV (PLWH). We assessed at study entry the QOL of antiretroviral-naïve PLWH with CD4 counts > 500 cells/µL in the Strategic Timing of AntiRetroviral Treatment (START) clinical trial. METHODS: QOL was assessed with: (1) a visual analogue scale (VAS) for self-assessment of overall current health; (2) the Short-Form 12-Item Version 2 Health Survey(®) (SF-12V2), for which responses are summarized into eight individual QOL domains plus component summary scores for physical health [the Physical Health Component Summary (PCS)] and mental health [the Mental Health Component Summary (MCS)]. The VAS and eight domain scores were scaled from 0 to 100. Mean QOL measures were calculated overall and by demographic, clinical and behavioural factors. RESULTS: A total of 4631 participants completed the VAS and 4119 the SF-12. The mean VAS score (with standard deviation) was 80.9 ± 15.7. Mean SF-12 domain scores were lowest for vitality (66.3 ± 26.4) and mental health (68.6 ± 21.4), and highest for physical functioning (89.3 ± 23.0) and bodily pain (88.0 ± 21.4). Using multiple linear regression, PCS scores were lower (P < 0.001) for Asians, North Americans, female participants, older participants, and those with less education, longer duration of known HIV infection, alcoholism/substance dependence and body mass index ≥ 30 kg/m(2) . MCS scores were highest (P < 0.001) for Africans, South Americans and older participants, and lowest for female participants, current smokers and those with alcoholism/substance dependence. CONCLUSIONS: In this primarily healthy population, QOL was mostly favourable, emphasizing that it is important that HIV treatments do not negatively impact QOL. Self-assessed physical health summary scores were higher than mental health scores. Factors such as older age and geographical region had different effects on perceived physical and mental health.

Solar eclipses of Phobos and Deimos observed from the surface of Mars.

The small martian satellites Phobos and Deimos orbit in synchronous rotation with inclinations of only 0.01 degrees and 0.92 degrees , respectively, relative to the planet's equatorial plane. Thus, an observer at near-equatorial latitudes on Mars could occasionally observe solar eclipses by these satellites (see ref. 1, for example). Because the apparent angular diameter of the satellites is much smaller than that of the Sun, however, such events are more appropriately referred to as transits. Transit data can be used for correcting and refining the orbital ephemerides of the moons. For example, Phobos is known to exhibit a secular acceleration that is caused by tidal dissipation within Mars. Long-term, accurate measurements are needed to refine the magnitude and origin of this dissipation within the martian interior as well as to refine the predicted orbital evolution of both satellites. Here we present observations of six transits of Phobos and Deimos across the solar disk from cameras on Mars aboard the Mars Exploration Rovers Spirit and Opportunity. These are the first direct imaging observations of satellites transiting the Sun from the surface of another planet.

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.

ON THE COMPOSITION OF YOUNG, DIRECTLY IMAGED GIANT PLANETS.

The past decade has seen significant progress on the direct detection and characterization of young, self-luminous giant planets at wide orbital separations from their host stars. Some of these planets show evidence for disequilibrium processes like transport-induced quenching in their atmospheres; photochemistry may also be important, despite the large orbital distances. These disequilibrium chemical processes can alter the expected composition, spectral behavior, thermal structure, and cooling history of the planets, and can potentially confuse determinations of bulk elemental ratios, which provide important insights into planet-formation mechanisms. Using a thermo/photochemical kinetics and transport model, we investigate the extent to which disequilibrium chemistry affects the composition and spectra of directly imaged giant exoplanets. Results for specific "young Jupiters" such as HR 8799 b and 51 Eri b are presented, as are general trends as a function of planetary effective temperature, surface gravity, incident ultraviolet flux, and strength of deep atmospheric convection. We find that quenching is very important on young Jupiters, leading to CO/CH4 and N2/NH3 ratios much greater than, and H2O mixing ratios a factor of a few less than, chemical-equilibrium predictions. Photochemistry can also be important on such planets, with CO2 and HCN being key photochemical products. Carbon dioxide becomes a major constituent when stratospheric temperatures are low and recycling of water via the H2 + OH reaction becomes kinetically stifled. Young Jupiters with effective temperatures ≲700 K are in a particularly interesting photochemical regime that differs from both transiting hot Jupiters and our own solar-system giant planets.

Anatomy and embryology of the trigeminal nerve and its branches in the parasellar area.

The cavum trigeminale (Meckel's cave) anatomy is still poorly understood. Many different descriptions are found in the literature. In order to clarify the relationship of trigeminal ganglion and its branches with dura and arachnoid, we underwent an embryological and adult microanatomical and histological study. Serial sections of human embryos and fetuses were used. For adult study, microdissections and histological serial sections were performed. We found that dura and arachnoid stop at the trigeminal ganglion and do not extend the three branches of the trigeminal nerve. These three branches are embedded into separate peripheral sheaths. These results are important for clear understanding of the anatomy of the parasellar lodge (cavernous sinus) lateral wall.

The venous system of the lateral sellar compartment (cavernous sinus): an histological and embryological study.

The microanatomy of the lateral sellar or parasellar venous system (so-called cavernous sinus) is poorly understood and is still passionately debated. The exact nature of this venous structure is not yet clear whether it is a plexus or a sinus. In order to understand the anatomy of this area better, an embryological and adult microanatomical study was performed. Serial histological sections of human embryos and fetuses of well determined ages (6, 7, 8, 10, 11, 12, 14, 30 weeks) were used. The adult study was performed with microdissections and serial histological sections of laterosellar compartments. The analysis of this material confirms that the parasellar venous system is a true sinus, on the embryological and histological point of view. They differ from true veins. As other dural sinuses, it may contain different types of channels: from simple venous canal to complex venous plexus. The opinions of different authors are reviewed in the introduction and discussed with the results.

IL-22-producing CD4+ cells are depleted in actively inflamed colitis tissue.

T helper type (Th17) cytokines such as interleukin (IL)-17A and IL-22 are important in maintaining mucosal barrier function and may be important in the pathogenesis of inflammatory bowel diseases (IBDs). Here, we analyzed cells from the colon of IBD patients and show that Crohn's disease (CD) patients had significantly elevated numbers of IL-17+, CD4+ cells compared with healthy controls and ulcerative colitis (UC) patients, but these numbers did not vary based on the inflammatory status of the mucosa. By contrast, UC patients had significantly reduced numbers of IL-22+ cells in actively inflamed tissues compared with both normal tissue and healthy controls. There was a selective increase in mono-IL-17-producing cells from the mucosa of UC patients with active inflammation together with increased expression of transforming growth factor (TGF)-ß and c-Maf. Increasing concentrations of TGF-ß in lamina propria mononuclear cell cultures significantly depleted Th22 cells, whereas anti-TGF-ß antibodies increased IL-22 production. When mucosal microbiota was examined, depletion of Th22 cells in actively inflamed tissue was associated with reduced populations of Clostridiales and increased populations of Proteobacteria. These results suggest that increased TGF-ß during active inflammation in UC may lead to the loss of Th22 cells in the human intestinal mucosa.

Ancient aqueous environments at Endeavour crater, Mars.

Opportunity has investigated in detail rocks on the rim of the Noachian age Endeavour crater, where orbital spectral reflectance signatures indicate the presence of Fe(+3)-rich smectites. The signatures are associated with fine-grained, layered rocks containing spherules of diagenetic or impact origin. The layered rocks are overlain by breccias, and both units are cut by calcium sulfate veins precipitated from fluids that circulated after the Endeavour impact. Compositional data for fractures in the layered rocks suggest formation of Al-rich smectites by aqueous leaching. Evidence is thus preserved for water-rock interactions before and after the impact, with aqueous environments of slightly acidic to circum-neutral pH that would have been more favorable for prebiotic chemistry and microorganisms than those recorded by younger sulfate-rich rocks at Meridiani Planum.

Use and misuse of antibiotics in Latin America.

Some common characteristics that distinguish antibiotic use in Latin America are a high incidence of infections that are treatable with antibiotics, extensive use and frequent misuse of antibiotics, and frequent self-medication and nonprofessional prescription in the outpatient setting. Community-acquired organisms are generally more antibiotic-resistant in Latin America than in more-industrialized countries. Antibiotics also are used extensively in hospitals, largely for surgical prophylaxis and for nosocomial infections, which occur more frequently (in 15%-20%) in hospitalized patients. Prophylactic use of antibiotics is largely inappropriate--i.e., indiscriminate, inopportune, and prolonged. A frequent outcome of this inappropriate use is the occurrence of nosocomial infections due to strains that are much more drug resistant than those encountered in industrialized countries. The great number of pharmaceutical products available, and the lack of stringent policies regarding drug sales and advertising often result in pressure to prescribe and in confusion not only among the public at large but among physicians themselves. Coordinated efforts to educate health care professionals, campaigns against self-medication, stricter rules for drug sales and advertising, and restricted use of certain antibiotics in hospitals may contribute to rational antibiotic use.

Splenic abscesses due to Mycobacterium tuberculosis in patients with AIDS.

Among 60 patients with AIDS seen at our institution, two had splenic abscesses due to Mycobacterium tuberculosis without pulmonary tuberculosis. In both cases splenic abscess was the first manifestation of AIDS; the patients had prolonged fever and had lost weight and experienced malaise; slight hepatomegaly was noted in both instances and peripheral lymphadenopathy in one. Chest radiography gave normal results in one case and showed hilar lymphadenopathy in the other. Ultrasonographic findings were characteristic: homogeneous hepatomegaly and splenomegaly, with multiple filling defects of variable size. Diagnosis required splenectomy in one case and biopsy of cervical lymph nodes in the other. In both cases Ziehl-Neelsen staining gave positive results; M. tuberculosis grew from a culture of splenic tissue of one patient and from a culture of lymph nodal tissue of the other. There was a rapid response to antituberculous therapy. Splenic tuberculosis seems to be a distinct extrapulmonary entity in patients with AIDS. Ultrasonographic images are useful for diagnosis and follow-up.

Endocrine neoplasia in New World primates.

Of 1,106 New World primates necropsied from the National Zoological Park (Washington, D.C.) and the Department of Comparative Pathology, Johns Hopkins University School of Medicine (Baltimore, Maryland) 22 (1.9%) animals were identified with 27 neoplasms. Of this group, nine animals (two females, seven males) had a total of 13 endocrine neoplasms. All animals were adults, with an age range of 2.7-25 years (average, 12.1 years). Seven were Callitrichidae and two were Cebidae. The adrenal gland was the most affected organ, with seven (53.8%) neoplasms, followed by the pituitary and thyroid gland with two (15.4%) cases each, and the pancreas and parathyroid gland with one tumor (7.7%) each. All neoplastic disorders were benign. Immunocytochemistry assays for growth hormone, adrenocorticotropic hormone, prolactin, follicle-stimulating hormone, luteinizing hormone, thyroid-stimulating hormone, and chromogranin A were performed on two pituitary neoplasms. Pheochromocytoma was the most frequent neoplasm, representing 5 (38.4%) of the 13 neoplasms. The remaining were thyroid cystadenoma (two, 15.4%), corticotrophic cell pituitary adenoma (two, 15.4%), adrenal ganglioneuroma (one, 7.7%), adrenal cortical adenoma (one, 7.7%), parathyroid chief-cell adenoma (one, 7.7%), and pancreatic islet-cell adenoma (one, 7.7%).

Atmospheric imaging results from the Mars exploration rovers: Spirit and Opportunity.

A visible atmospheric optical depth of 0.9 was measured by the Spirit rover at Gusev crater and by the Opportunity rover at Meridiani Planum. Optical depth decreased by about 0.6 to 0.7% per sol through both 90-sol primary missions. The vertical distribution of atmospheric dust at Gusev crater was consistent with uniform mixing, with a measured scale height of 11.56 +/- 0.62 kilometers. The dust's cross section weighted mean radius was 1.47 +/- 0.21 micrometers (mm) at Gusev and 1.52 +/- 0.18 mm at Meridiani. Comparison of visible optical depths with 9-mm optical depths shows a visible-to-infrared optical depth ratio of 2.0 +/- 0.2 for comparison with previous monitoring of infrared optical depths.

Initial results from the Mini-TES experiment in Gusev Crater from the Spirit Rover.

The Miniature Thermal Emission Spectrometer (Mini-TES) on Spirit has studied the mineralogy and thermophysical properties at Gusev crater. Undisturbed soil spectra show evidence for minor carbonates and bound water. Rocks are olivinerich basalts with varying degrees of dust and other coatings. Dark-toned soils observed on disturbed surfaces may be derived from rocks and have derived mineralogy (+/-5 to 10%) of 45% pyroxene (20% Ca-rich pyroxene and 25% pigeonite), 40% sodic to intermediate plagioclase, and 15% olivine (forsterite 45% +/-5 to 10). Two spectrally distinct coatings are observed on rocks, a possible indicator of the interaction of water, rock, and airfall dust. Diurnal temperature data indicate particle sizes from 40 to 80 microm in hollows to approximately 0.5 to 3 mm in soils.

Mineralogy at Meridiani Planum from the Mini-TES Experiment on the Opportunity Rover.

The Miniature Thermal Emission Spectrometer (Mini-TES) on Opportunity investigated the mineral abundances and compositions of outcrops, rocks, and soils at Meridiani Planum. Coarse crystalline hematite and olivine-rich basaltic sands were observed as predicted from orbital TES spectroscopy. Outcrops of aqueous origin are composed of 15 to 35% by volume magnesium and calcium sulfates [a high-silica component modeled as a combination of glass, feldspar, and sheet silicates (approximately 20 to 30%)], and hematite; only minor jarosite is identified in Mini-TES spectra. Mini-TES spectra show only a hematite signature in the millimeter-sized spherules. Basaltic materials have more plagioclase than pyroxene, contain olivine, and are similar in inferred mineral composition to basalt mapped from orbit. Bounce rock is dominated by clinopyroxene and is close in inferred mineral composition to the basaltic martian meteorites. Bright wind streak material matches global dust. Waterlain rocks covered by unaltered basaltic sands suggest a change from an aqueous environment to one dominated by physical weathering.

Pancam multispectral imaging results from the Spirit Rover at Gusev Crater.

Panoramic Camera images at Gusev crater reveal a rock-strewn surface interspersed with high- to moderate-albedo fine-grained deposits occurring in part as drifts or in small circular swales or hollows. Optically thick coatings of fine-grained ferric iron-rich dust dominate most bright soil and rock surfaces. Spectra of some darker rock surfaces and rock regions exposed by brushing or grinding show near-infrared spectral signatures consistent with the presence of mafic silicates such as pyroxene or olivine. Atmospheric observations show a steady decline in dust opacity during the mission, and astronomical observations captured solar transits by the martian moons, Phobos and Deimos, as well as a view of Earth from the martian surface.

Pancam multispectral imaging results from the Opportunity Rover at Meridiani Planum.

Panoramic Camera (Pancam) images from Meridiani Planum reveal a low-albedo, generally flat, and relatively rock-free surface. Within and around impact craters and fractures, laminated outcrop rocks with higher albedo are observed. Fine-grained materials include dark sand, bright ferric iron-rich dust, angular rock clasts, and millimeter-size spheroidal granules that are eroding out of the laminated rocks. Spectra of sand, clasts, and one dark plains rock are consistent with mafic silicates such as pyroxene and olivine. Spectra of both the spherules and the laminated outcrop materials indicate the presence of crystalline ferric oxides or oxyhydroxides. Atmospheric observations show a steady decline in dust opacity during the mission. Astronomical observations captured solar transits by Phobos and Deimos and time-lapse observations of sunsets.