The Pluto system was recently explored by NASA's New Horizons spacecraft, making closest approach on 14 July 2015. Pluto's surface displays diverse landforms, terrain ages, albedos, colors, and ...composition gradients. Evidence is found for a water-ice crust, geologically young surface units, surface ice convection, wind streaks, volatile transport, and glacial flow. Pluto's atmosphere is highly extended, with trace hydrocarbons, a global haze layer, and a surface pressure near 10 microbars. Pluto's diverse surface geology and long-term activity raise fundamental questions about how small planets remain active many billions of years after formation. Pluto's large moon Charon displays tectonics and evidence for a heterogeneous crustal composition; its north pole displays puzzling dark terrain. Small satellites Hydra and Nix have higher albedos than expected.
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The Kuiper Belt is a broad, torus-shaped region in the outer Solar System beyond Neptune’s orbit. It contains primordial planetary building blocks and dwarf planets. NASA’s New Horizons spacecraft ...conducted a flyby of Pluto and its system of moons on 14 July 2015. New Horizons then continued farther into the Kuiper Belt, adjusting its trajectory to fly close to the small Kuiper Belt object (486958) 2014 MU69 (henceforth MU69; also informally known as Ultima Thule). Stellar occultation observations in 2017 showed that MU69 was ~25 to 35 km in diameter, and therefore smaller than the diameter of Pluto (2375 km) by a factor of ~100 and less massive than Pluto by a factor of ~106. MU69 is located about 1.6 billion kilometers farther from the Sun than Pluto was at the time of the New Horizons flyby. MU69’s orbit indicates that it is a “cold classical” Kuiper Belt object, thought to be the least dynamically evolved population in the Solar System. A major goal of flying past this target is to investigate accretion processes in the outer Solar System and how those processes led to the formation of the planets. Because no small Kuiper Belt object had previously been explored by spacecraft, we also sought to provide a close-up look at such a body’s geology and composition, and to search for satellites, rings, and evidence of present or past atmosphere. We report initial scientific results and interpretations from that flyby.
The atmosphere of Pluto as observed by New Horizons Gladstone, G. Randall; Stern, S. Alan; Ennico, Kimberly ...
Science (American Association for the Advancement of Science),
03/2016, Volume:
351, Issue:
6279
Journal Article
Peer reviewed
Open access
Observations made during the New Horizons flyby provide a detailed snapshot of the current state of Pluto's atmosphere. Whereas the lower atmosphere (at altitudes of less than 200 kilometers) is ...consistent with ground-based stellar occultations, the upper atmosphere is much colder and more compact than indicated by pre-encounter models. Molecular nitrogen (N2) dominates the atmosphere (at altitudes of less than 1800 kilometers or so), whereas methane (CH4), acetylene (C2H2), ethylene (C2H4), and ethane (C2H6) are abundant minor species and likely feed the production of an extensive haze that encompasses Pluto. The cold upper atmosphere shuts off the anticipated enhanced-Jeans, hydrodynamic-like escape of Pluto's atmosphere to space. It is unclear whether the current state of Pluto's atmosphere is representative of its average state--over seasonal or geologic time scales.
NASA's New Horizons spacecraft has revealed the complex geology of Pluto and Charon. Pluto's encounter hemisphere shows ongoing surface geological activity centered on a vast basin containing a thick ...layer of volatile ices that appears to be involved in convection and advection, with a crater retention age no greater than ~10 million years. Surrounding terrains show active glacial flow, apparent transport and rotation of large buoyant water-ice crustal blocks, and pitting, the latter likely caused by sublimation erosion and/or collapse. More enigmatic features include tall mounds with central depressions that are conceivably cryovolcanic and ridges with complex bladed textures. Pluto also has ancient cratered terrains up to ~4 billion years old that are extensionally faulted and extensively mantled and perhaps eroded by glacial or other processes. Charon does not appear to be currently active, but experienced major extensional tectonism and resurfacing (probably cryovolcanic) nearly 4 billion years ago. Impact crater populations on Pluto and Charon are not consistent with the steepest impactor size-frequency distributions proposed for the Kuiper belt.
The New Horizons spacecraft carried three instruments that measured the space environment near Pluto as it flew by on 14 July 2015. The Solar Wind Around Pluto (SWAP) instrument revealed an ...interaction region confined sunward of Pluto to within about 6 Pluto radii. The region's surprisingly small size is consistent with a reduced atmospheric escape rate, as well as a particularly high solar wind flux. Observations from the Pluto Energetic Particle Spectrometer Science Investigation (PEPSSI) instrument suggest that ions are accelerated and/or deflected around Pluto. In the wake of the interaction region, PEPSSI observed suprathermal particle fluxes equal to about 1/10 of the flux in the interplanetary medium and increasing with distance downstream. The Venetia Burney Student Dust Counter, which measures grains with radii larger than 1.4 micrometers, detected one candidate impact in ±5 days around New Horizons' closest approach, indicating an upper limit of <4.6 kilometers(-3) for the dust density in the Pluto system.
Department of Ophthalmology, University of Freiburg, Killianstr. 5, 79106 Freiburg, Germany 1
Neurotoxicology Section, National Institute of Neurological Disorders and Stroke, National Institutes of ...Health, 36 Convent Drive, Room 4A-27, MD 20892-4126, Bethesda, USA 2
Department of Microbiology, Faculty of Biology, University of Barcelona, 08028 Barcelona, Spain 3
University Eye Clinic II, SPKSO, Sierakowskiego 13, 03709 Warsaw, Poland 4
Department of Microbiology, Hospital Universitari Germans Trias i Pujol, E-08916 Badalona, Spain 5
Microbiology Department, Donostia Hospital, E-20014 San Sebastián, Spain 6
Author for correspondence: Gerald Stoner. Fax +1 301 496 7297. e-mail stonerg{at}ninds.nih.gov
Distinctive genotypes of JC virus have been described for the major continental landmasses. Studies on European-Americans and small cohorts in Europe showed predominantly Type 1. Types 2 and 7 are found in Asia, and Types 3 and 6 in Africa. These genotypes differ in sequence by about 13%. Each genotype may have several subtypes which differ from each other by about 0·51%. The genotypes can be defined by a distinctive pattern of nucleotides in a typing region of the VP 1 gene. This genotyping approach has been confirmed by phylogenetic reconstruction using the entire genome exclusive of the rearranging regulatory region. In this first large European study, we report on the urinary excretion of JCV DNA of 350 individuals from Poland, Hungary, Germany and Spain. We included Gypsy cohorts in Hungary (Roma), Germany (Sinti), and Spain (Gitano), as well as Basques in Spain. We show that while Type 1 predominates in Europe, the proportions of Type 1A and 1B may differ from East to Southwest Europe. Type 4, closely related to the Type 1 sequence (only 1% difference) was a minor genotype in Germany, Poland and Spain, but represented the majority in Basques. The Gitanos in Spain showed a variant Type 4 sequence termed Rom-1. Interestingly, neither the Gitanos in Spain, nor Sinti or Roma in Germany or Hungary showed the Type 2 or Type 7 genotype that might be expected if their origins were in an Asian population.
The Kuiper Belt is a distant region of the outer Solar System. On 1 January 2019, the New Horizons spacecraft flew close to (486958) 2014 MU
, a cold classical Kuiper Belt object approximately 30 ...kilometers in diameter. Such objects have never been substantially heated by the Sun and are therefore well preserved since their formation. We describe initial results from these encounter observations. MU
is a bilobed contact binary with a flattened shape, discrete geological units, and noticeable albedo heterogeneity. However, there is little surface color or compositional heterogeneity. No evidence for satellites, rings or other dust structures, a gas coma, or solar wind interactions was detected. MU
's origin appears consistent with pebble cloud collapse followed by a low-velocity merger of its two lobes.
In a previous study, we performed serial BK virus (BKV), polymerase chain reaction (PCR) and detected active BKV infection in 70 (35.4%) of 198 renal transplant recipients. In the current study, ...pre‐transplant donor and recipient samples were analyzed for BKV antibody titer and HLA alleles. Donor antibody titer was inversely proportional to onset of viruria, p < 0.001, directly proportional to duration of viruria, p = 0.014 and directly proportional to peak urine viral titer p = 0.005. Recipient pairs receiving kidneys from the same donor were concordant for BKV infection, p = 0.017, and had matched sequences of segments of the NCCR and VP1 genes that tended to vary among recipients of kidneys from different donors. We did not see an association of HLA A, B, or DR, HLA allele mismatches or total HLA mismatches and BK infection. However, all 11 recipients with sustained BK viremia received kidneys from donors lacking HLA C7, and 10 recipients also lacked C7. These findings derive from the largest and most comprehensive prospective study of BKV infection in renal transplant recipients performed to date. Our data support donor origin for early BKV infection in kidney transplant recipients, and suggest that a specific HLA C locus may be associated with failure to control BKV infection.
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BFBNIB, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Abstract Background The mean urine BK viral load in kidney transplant recipients increases with the intensity of infection as the infection progresses from transient viruria to sustained viremia. ...Objectives This study investigated whether the intensity of infection is associated with the humoral immune response. Study design We measured BKV-specific IgG antibody titers in stored samples obtained serially over a 1-year period from 70 kidney transplant recipients with BKV infection and 17 control recipients without active BKV infection. Results The mean pre-transplant BKV antibody level was lower in recipients who developed viremia than the mean level in those who never developed viremia ( p = 0.004). Mean antibody titers in recipients who never showed evidence of active BKV infection rose slightly after transplant despite immunosuppression. The magnitude of the rise in the mean antibody titers in recipients who developed active BKV infection correlated with the intensity of infection ( p < 0.001). Conclusions The mean antibody level increased in accordance with the intensity of the infection post-transplant. Pre-transplant seropositivity did not protect against sustained viremia and the antibody response was not associated with clearance of the virus.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
The Johns Hopkins University Applied Physics Laboratory (APL) Space Exploration Sector (recently renamed from the Space Department) evolved from focusing mostly on national security needs to ...including missions in which civilian space assumed a leading role. This transition started in the 1980s but accelerated significantly after the end of the Cold War in the early 1990s. It coincided with the preceding decade’s scarcity of medium-class planetary missions, which necessitated a new paradigm of small, science-focused projects that had limited objectives, could be developed and flown in about 3 years, entailed moderate cost, and posed low risk; this paradigm became the Discovery Program. APL was particularly well suited for this type of operation, having worked previously with the NASA Explorer program. Similarly, national security needs evolved from single missions intended to obtain a specific set of measurements, such as the Midcourse Space Experiment (MSX), to multi-spacecraft aggregates employing a new generation of high-level small satellites capable of meeting DoD’s and other sponsors’ need for reliability, flexibility, and performance at substantially lower costs. This article describes APL’s contributions to space science and national security beginning with the start of these changes in the 1990s and continuing to the present.
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