20,313 research outputs found
Beltway: Getting Around Garbage Collection Gridlock
We present the design and implementation of a new garbage collection framework that significantly generalizes existing copying collectors. The Beltway framework exploits and separates object age and incrementality. It groups objects in one or more increments on queues called belts, collects belts independently, and collects increments on a belt in first-in-first-out order. We show that Beltway configurations, selected by command line options, act and perform the same as semi-space, generational, and older-first collectors, and encompass all previous copying collectors of which we are aware. The increasing reliance on garbage collected languages such as Java requires that the collector perform well. We show that the generality of Beltway enables us to design and implement new collectors that are robust to variations in heap size and improve total execution time over the best generational copying collectors of which we are aware by up to 40%, and on average by 5 to 10%, for small to moderate heap sizes. New garbage collection algorithms are rare, and yet we define not just one, but a new family of collectors that subsumes previous work. This generality enables us to explore a larger design space and build better collectors
Dilepton Production at Fermilab and RHIC
Some recent results from several fixed-target dimuon production experiments
at Fermilab are presented. In particular, we discuss the use of Drell-Yan data
to determine the flavor structure of the nucleon sea, as well as to deduce the
energy-loss of partons traversing nuclear medium. Future dilepton experiments
at RHIC could shed more light on the flavor asymmetry and possible
charge-symmetry-violation of the nucleon sea. Clear evidence for scaling
violation in the Drell-Yan process could also be revealed at RHIC.Comment: 5 pages, talk presented at the RIKEN-BNL Workshop on 'Hard Parton
Physics in Nucleus-Nucleus collisions, March 199
Advanced flight deck/crew station simulator functional requirements
This report documents a study of flight deck/crew system research facility requirements for investigating issues involved with developing systems, and procedures for interfacing transport aircraft with air traffic control systems planned for 1985 to 2000. Crew system needs of NASA, the U.S. Air Force, and industry were investigated and reported. A matrix of these is included, as are recommended functional requirements and design criteria for simulation facilities in which to conduct this research. Methods of exploiting the commonality and similarity in facilities are identified, and plans for exploiting this in order to reduce implementation costs and allow efficient transfer of experiments from one facility to another are presented
Investigation in haemodynamic stability during intermittent haemodialysis in the critically ill
No abstract available
Anode-Coupled Readout for Light Collection in Liquid Argon TPCs
This paper will discuss a new method of signal read-out from photon detectors
in ultra-large, underground liquid argon time projection chambers. In this
design, the signal from the light collection system is coupled via capacitive
plates to the TPC wire-planes. This signal is then read out using the same
cabling and electronics as the charge information. This greatly benefits light
collection: it eliminates the need for an independent readout, substantially
reducing cost; It reduces the number of cables in the vapor region of the TPC
that can produce impurities; And it cuts down on the number of feed-throughs in
the cryostat wall that can cause heat-leaks and potential points of failure. We
present experimental results that demonstrate the sensitivity of a LArTPC wire
plane to photon detector signals. We also simulate the effect of a 1 s
shaping time and a 2 MHz sampling rate on these signals in the presence of
noise, and find that a single photoelectron timing resolution of 30 ns
can be achieved.Comment: 16 pages, 15 figure
An investigation into the effects of commencing haemodialysis in the critically ill
<b>Introduction:</b>
We have aimed to describe haemodynamic changes when haemodialysis is instituted in the critically ill. 3
hypotheses are tested: 1)The initial session is associated with cardiovascular instability, 2)The initial session is
associated with more cardiovascular instability compared to subsequent sessions, and 3)Looking at unstable
sessions alone, there will be a greater proportion of potentially harmful changes in the initial sessions compared
to subsequent ones.
<b>Methods:</b>
Data was collected for 209 patients, identifying 1605 dialysis sessions. Analysis was performed on hourly
records, classifying sessions as stable/unstable by a cutoff of >+/-20% change in baseline physiology
(HR/MAP). Data from 3 hours prior, and 4 hours after dialysis was included, and average and minimum values
derived. 3 time comparisons were made (pre-HD:during, during HD:post, pre-HD:post). Initial sessions were
analysed separately from subsequent sessions to derive 2 groups. If a session was identified as being unstable,
then the nature of instability was examined by recording whether changes crossed defined physiological ranges.
The changes seen in unstable sessions could be described as to their effects: being harmful/potentially harmful,
or beneficial/potentially beneficial.
<b>Results:</b>
Discarding incomplete data, 181 initial and 1382 subsequent sessions were analysed. A session was deemed to
be stable if there was no significant change (>+/-20%) in the time-averaged or minimum MAP/HR across time
comparisons. By this definition 85/181 initial sessions were unstable (47%, 95% CI SEM 39.8-54.2). Therefore
Hypothesis 1 is accepted. This compares to 44% of subsequent sessions (95% CI 41.1-46.3). Comparing these
proportions and their respective CI gives a 95% CI for the standard error of the difference of -4% to 10%.
Therefore Hypothesis 2 is rejected. In initial sessions there were 92/1020 harmful changes. This gives a
proportion of 9.0% (95% CI SEM 7.4-10.9). In the subsequent sessions there were 712/7248 harmful changes.
This gives a proportion of 9.8% (95% CI SEM 9.1-10.5). Comparing the two unpaired proportions gives a
difference of -0.08% with a 95% CI of the SE of the difference of -2.5 to +1.2. Hypothesis 3 is rejected. Fisher’s
exact test gives a result of p=0.68, reinforcing the lack of significant variance.
<b>Conclusions:</b>
Our results reject the claims that using haemodialysis is an inherently unstable choice of therapy. Although
proportionally more of the initial sessions are classed as unstable, the majority of MAP and HR changes are
beneficial in nature
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