188 research outputs found
The albedo-color diversity of transneptunian objects
We analyze albedo data obtained using the Herschel Space Observatory that
reveal the existence of two distinct types of surface among midsized
transneptunian objects. A color-albedo diagram shows two large clusters of
objects, one redder and higher albedo and another darker and more neutrally
colored. Crucially, all objects in our sample located in dynamically stable
orbits within the classical Kuiper belt region and beyond are confined to the
bright-red group, implying a compositional link. Those objects are believed to
have formed further from the Sun than the dark-neutral bodies. This
color-albedo separation is evidence for a compositional discontinuity in the
young solar system.Comment: 16 pages, 4 figures, 1 table, published in ApJL (12 August 2014), The
Astrophysical Journal (2014), vol. 793, L
Demagnetization Monitoring and Identification in PM Generators With Concentrated Windings During Transient Conditions
Майданецьке 2013. Нові розкопки на трипільському мега-поселенні
In 2013 the first excavation campaign took place in Maidanetske by a joint interdisciplinary Ukrainian/
German team. Many aspects of the environment, economy and household organisation of Maidanetske
and Trypillia mega-sites (Russian “Tripolye”) in general can now be discussed based on a new
range of data. There are new arguments for an anthropogenically-induced transformation of the
original forest steppe into steppe vegetation during the existence of Maidanetske. Numerous radiometric
dates and typochronological discussions demonstrate that it is most probable that the houses
of the concentric rings existed contemporarily, resulting in population calculations of approximately
15,000 inhabitants. Important new information on subsistence economy was gathered, especially
through the analyses of botanical macro-remains and phytoliths. The excavations also revealed the
spatial organisation of one “normal” domestic house(hold) and its “house place”, while two pits also
indicate feasting and ritual activities, probably not within a single household, but a different ‘political’
supra-household level. In chronological terms the burning of houses around 3700 BCE is one ‘story’;
burnt remains in pits (dating to the 39th century BCE) is a different ‘story’, perhaps linked to the deliberate
(also ritual) deposition of earlier house remains
WiSer: A Highly Available HTAP DBMS for IoT Applications
In a classic transactional distributed database management system (DBMS),
write transactions invariably synchronize with a coordinator before final
commitment. While enforcing serializability, this model has long been
criticized for not satisfying the applications' availability requirements. When
entering the era of Internet of Things (IoT), this problem has become more
severe, as an increasing number of applications call for the capability of
hybrid transactional and analytical processing (HTAP), where aggregation
constraints need to be enforced as part of transactions. Current systems work
around this by creating escrows, allowing occasional overshoots of constraints,
which are handled via compensating application logic.
The WiSer DBMS targets consistency with availability, by splitting the
database commit into two steps. First, a PROMISE step that corresponds to what
humans are used to as commitment, and runs without talking to a coordinator.
Second, a SERIALIZE step, that fixes transactions' positions in the
serializable order, via a consensus procedure. We achieve this split via a
novel data representation that embeds read-sets into transaction deltas, and
serialization sequence numbers into table rows. WiSer does no sharding (all
nodes can run transactions that modify the entire database), and yet enforces
aggregation constraints. Both readwrite conflicts and aggregation constraint
violations are resolved lazily in the serialized data. WiSer also covers node
joins and departures as database tables, thus simplifying correctness and
failure handling. We present the design of WiSer as well as experiments
suggesting this approach has promise
Thoughts on opportunities from high-energy nuclear collisions
This document summarizes thoughts on opportunities from high-energy nuclear
collisions.Comment: 10 pages, pd
Spectroscopic time series performance of the Mid-Infrared Instrument on the JWST
We present here the first ever mid-infrared spectroscopic time series
observation of the transiting exoplanet \object{L 168-9 b} with the
Mid-Infrared Instrument (MIRI) on the James Webb Space Telescope. The data were
obtained as part of the MIRI commissioning activities, to characterize the
performance of the Low Resolution Spectroscopy (LRS) mode for these challenging
observations. To assess the MIRI LRS performance, we performed two independent
analyses of the data. We find that with a single transit observation we reached
a spectro-photometric precision of 50 ppm in the 7-8 \micron range at
R=50, consistent with 25 ppm systematic noise. The derived band averaged
transit depth is 524 15 ppm and 547 13 ppm for the two applied
analysis methods, respectively, recovering the known transit depth to within 1
. The measured noise in the planet's transmission spectrum is
approximately 15-20 \% higher than random noise simulations over wavelengths
m. \added{We observed an larger excess
noise at the shortest wavelengths of up to a factor of two, for which possible
causes are discussed.} This performance was achieved with limited in-flight
calibration data, demonstrating the future potential of MIRI for the
characterization of exoplanet atmospheres.Comment: Accepted for publishing in PASP, 21 pages, 10 figure
A multicenter randomized-controlled trial of hypothermic oxygenated perfusion (HOPE) for human liver grafts before transplantation
Background & Aims: Machine perfusion is a novel method intended to optimize livers before transplantation. However, its effect on morbidity within a 1-year period after transplantation has remained unclear. Methods: In this multicenter controlled trial, we randomly assigned livers donated after brain death (DBD) for liver transplantation (LT). Livers were either conventionally cold stored (control group), or cold stored and subsequently treated by 1-2 h hypothermic oxygenated perfusion (HOPE) before implantation (HOPE group). The primary endpoint was the occurrence of at least one post-transplant complication per patient, graded by the Clavien score of ≥III, within 1-year after LT. The comprehensive complication index (CCI), laboratory parameters, as well as duration of hospital and intensive care unit stay, graft survival, patient survival, and biliary complications served as secondary endpoints. Results: Between April 2015 and August 2019, we randomized 177 livers, resulting in 170 liver transplantations (85 in the HOPE group and 85 in the control group). The number of patients with at least one Clavien ≥III complication was 46/85 (54.1%) in the control group and 44/85 (51.8%) in the HOPE group (odds ratio 0.91; 95% CI 0.50-1.66; p = 0.76). Secondary endpoints were also not significantly different between groups. A post hoc analysis revealed that liver-related Clavien ≥IIIb complications occurred less frequently in the HOPE group compared to the control group (risk ratio 0.26; 95% CI 0.07-0.77; p = 0.027). Likewise, graft failure due to liver-related complications did not occur in the HOPE group, but occurred in 7% (6 of 85) of the control group (log-rank test, p = 0.004, Gray test, p = 0.015). Conclusions: HOPE after cold storage of DBD livers resulted in similar proportions of patients with at least one Clavien ≥III complication compared to controls. Exploratory findings suggest that HOPE decreases the risk of severe liver graft-related events. Impact and implications: This randomized controlled phase III trial is the first to investigate the impact of hypothermic oxygenated perfusion (HOPE) on cumulative complications within a 12-month period after liver transplantation. Compared to conventional cold storage, HOPE did not have a significant effect on the number of patients with at least one Clavien ≥III complication. However, we believe that HOPE may have a beneficial effect on the quantity of complications per patient, based on its application leading to fewer severe liver graft-related complications, and to a lower risk of liver-related graft loss. The HOPE approach can be applied easily after organ transport during recipient hepatectomy. This appears fundamental for wide acceptance since concurring perfusion technologies need either perfusion at donor sites or continuous perfusion during organ transport, which are much costlier and more laborious. We conclude therefore that the post hoc findings of this trial should be further validated in future studies.</p
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