Positron emission tomography allows noninvasive assessment of myocardial blood flow and metabolism, and may aid in defining the extent and severity of an ischemic injury. This hypothesis was tested by studying, in chronically instrumented dogs, regional blood flow and metabolism during and after a 3 hour balloon occlusion of the left anterior descending coronary artery. The metabolic findings after ischemia were compared with the recovery of regional function over a 4 week period. N-13 ammonia was used as a blood flow tracer, and C-11 palmitic acid and F-18 deoxyglucose as tracers of fatty acid and glucose metabolism, respectively. Regional myocardial function was monitored with ultrasonic crystals implanted subendocardially. Regional function improved most between 24 hours and 1 week after reperfusion, but was still attenuated at 4 weeks. The slow functional recovery was paralleled by sustained metabolic abnormalities, reflected by segmentally delayed clearance of C-11 activity from myocardium and increased uptake of F-18 deoxyglucose. Absence of blood flow and C-11 palmitic acid uptake at 24 hours of reperfusion correlated with extensive necrosis as evidenced by histologic examination. Conversely, uptake of C-11 palmitic acid with delayed C-11 clearance and increased F-18 deoxyglucose accumulation identified reversibly injured tissue that subsequently recovered functionally and revealed little necrosis. Thus, recovery of metabolism after 3 hours of ischemia is slow in canine myocardium and paralleled by slow recovery of function. Metabolic indexes by positron tomography early after reperfusion can identify necrotic and reversibly injured tissue. Positron tomography may therefore aid in defining the extent and prognosis of an ischemic injury in patients undergoing reperfusion during evolving myocardial infarction.

The Mars Science Laboratory (MSL) rover spent a full martian year exploring the phyllosilicate‐bearing Glen Torridon trough on the flank of Aeolis Mons in Gale crater, enabling in‐depth assessment of aeolian processes. MSL encountered erosional and depositional features recording a long aeolian history. The trough has served as a long‐term conduit for sand transport, probably involving many cycles of sand accumulation and deflation. Rock abrasion textures indicate sand‐driving winds blowing W‐SW (opposite of abrasion textures on the Greenheugh Pediment above the trough floor). Indurated megaripple surfaces with 2–5 mm grains contrast with seasonally active ripples having finer maximum grain sizes, indicating more vigorous saltation in the past. Active ripples display a broad continuum of wavelengths, as well as coarser grains at crests than troughs, consistent with origins as impact ripples. Orientations of a wind streak extending from a large ripple field, and sandy wind tails behind obstacles, indicate sand is driven W‐SW in the current era, approximately along the trough axis. Erosion of drill tailings piles was strongly seasonal, enhanced during late spring and early summer (perihelion). Climate modeling suggests W‐SW sand transport can be attributed to seasonal enhancement of nighttime regional winds entering Gale crater from the N, combined with local katabatic winds flowing down the slopes of Aeolis Mons. However, it is unclear whether sand transport at Glen Torridon is primarily from these wind components combining and acting simultaneously, or occurring in serial at different times of night; field evidence supports both possibilities.

This study constrains the lower bound of the scattering phase function of Martian water ice clouds (WICs) through the implementation of a new observation aboard the Mars Science Laboratory (MSL). The Phase Function Sky Survey (PFSS) was a multiple pointing all-sky observation taken with the navigation cameras (Navcam) aboard MSL. The PFSS was executed 35 times during the Aphelion Cloud Belt (ACB) season of Mars Year 34 over a solar longitude range of s = 61.4°− 156.5°. Twenty observations occurred in the morning hours between 06:00 and 09:30 LTST, and 15 runs occurred in the evening hours between 14:30 and 18:00 LTST, with an operationally required 2.5 hour gap on either side of local noon due the sun being located near zenith. The resultant WIC phase function was derived over an observed scattering angle range of 18.3° to 152.61°, normalized, and compared with 9 modeled phase functions: seven ice crystal habits and two Martian WIC phase functions currently being implemented in models. Through statistical chi-squared probability tests, the five most probable ice crystal geometries observed in the ACB WICs were aggregates, hexagonal solid columns, hollow columns, plates, and bullet rosettes with p-values greater than or equal to 0.60, 0.57,0.56,0.56, and 0.55, respectively. Droxtals and spheres had p-values of 0.35, and 0.2, making them less probable components of Martian WICs, but still statistically possible ones. Having a better understanding of the ice crystal habit and phase function of Martian water ice clouds directly benefits Martian climate models which currently assume spherical and cylindrical particles.

Recent immunophenotypic studies of hairy cell leukemia (HCL) have suggested specific patterns of immunoreactivity that may aid in diagnosis. We studied peripheral blood (PB) from 161 cases of HCL using two-color direct immunofluorescence flow cytometry and an extended panel of antibody combinations. Circulating hairy cells were identified by immunophenotypic features in 92% of the cases and could be detected even when representing < or = 1% of circulating lymphocytes. The 133 cases with > or = 2% detectable hairy cells were analyzed in detail. HCL showed a uniform and unique B-cell phenotype, with each of the following features identified in 99% to 100% of cases: (1) positive staining for B-ly7, coexpressed with CD19; (2) very intense, uniform expression of CD11c, with CD19; (3) moderately intense staining for CD25, with CD19; (4) very intense staining for CD22; (5) moderate to very intense staining for CD20; and (6) moderately intense monoclonal surface Ig. Phenotypic variability existed in expression of CD10 (26%) and CD5 (4%). Based on these features, HCL was easily distinguished from 50 cases of chronic lymphocytic leukemia (CLL). Although CLL exhibited frequent expression of CD11c (74%) and CD25 (68%), the intensity of staining was significantly less than HCL. Furthermore, CLL was uniformly positive for CD5 and showed weak staining for CD20, CD22, and surface Ig. B-ly7 proved to be the most specific marker, reacting with 100% of HCL cases, but absent in all cases of CLL. We conclude that two-color flow cytometry with specific antibody combinations is an efficacious method for characterization and sensitive detection of hairy cells in PB. Application of the phenotypic criteria described should help to increase accuracy in diagnosis of HCL.

Northern line‐of‐sight extinction within Gale Crater during the 2018 global dust storm was monitored daily using Mars Science Laboratory's Navcam. Additional observations with Mastcam (north) and Navcam (all directions) were obtained at a lower cadence. Using feature identification and georeferencing, extinction was estimated in all possible directions. Peak extinction of >1.1 km−1 was measured between sols 2086 and 2090, an order of magnitude higher than previous maxima. Northern and western directions show an initial decrease, followed by a secondary peak in extinction, not seen in column opacity measurements. Due to foreground topography, eastern direction results are provided only as limits, and southern results were indeterminable. Mastcam red and green filter results agree well, but blue filter results show higher extinctions, likely due to low signal‐to‐noise. Morning results are systematically higher than afternoon results, potentially indicative of atmospheric mixing.

Treatment of hairy cell leukemia with 2-chlorodeoxyadenosine (2-CdA) induces complete remissions in 85% of patients. Complete remission has been defined as the absence of hairy cells in the bone marrow after routine morphologic examination. To determine if hairy cells could be detected in complete remission bone marrows using immunohistochemical techniques with antibodies L26 (CD20) and DBA.44, 154 bone marrow biopsies performed between 3 months and 25 months after therapy were studied. Of the biopsies, 50% exhibited staining with L26 and/or DBA.44 in five or more cells with morphologic features of hairy cells. Minimal residual disease was usually less than 1% of the total cellular population. DBA.44-positive cells were demonstrated in 91% of the biopsies, although in 48% of these the morphologic features of the positive cells were not sufficiently distinctive for hairy cells. The proportion of biopsies with residual hairy cells was similar over the 25 months of follow up, indicating a relatively stable amount of residual disease. Immunomorphologic analysis is a more sensitive method for detecting residual hairy cells than morphology alone. Although further follow up is necessary to determine the clinical significance of the L26/DBA.44-positive staining in cells with and without distinctive morphologic features of hairy cells, we conclude that many patients in a stable clinical remission may have residual hairy cells.

A suite of high resolution cameras onboard the Mars Science Laboratory (MSL) Curiosity rover have provided an unparalleled look at active aeolian processes on Mars, including within the first active dune field explored on another planet, the Bagnold Dunes. Here we present results from a subset of MSL's repeat imaging (“change detection”) experiments with temporal resolutions sufficient to probe the diurnal variability in winds within Gale crater. Images reveal that saltation is a near‐daily phenomenon during southern summer, with repeatable diurnal circulation patterns producing steady impact ripple migration toward the west/southwest. Nighttime fluxes are inferred to be ∼four times larger than daytime fluxes, consistent with predictions from the MarsWRF model of multiple periods of enhanced wind between sunset and sunrise. Multiple factors are likely facilitating saltation at this time: (a) time‐averaged nighttime winds have a higher degree of variance (i.e., higher peak friction speeds) than daytime winds, (b) interactions between regional Hadley flows and local, thermally driven slope winds cause increased turbulence at night, and (c) relatively higher atmospheric density produces correspondingly higher shear stresses and decreases critical thresholds. Observations of sand transport at a range of spatiotemporal scales (down to scale of individual particles moving on the timescale of seconds) support the idea that bedform migration is driven by intermittent, low‐flux saltation events when winds fluctuate between canonical impact and fluid thresholds. Yet, whereas gustiness may play a role in initiating transport, saltation is found to be highly predictable on diurnal timescales and is only stochastic on the shortest timescales characteristic of turbulent fluctuations in wind.

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