57 research outputs found
Adding Explicit Load-Acquire and Store-Release Instructions to the RISC-V ISA
Weak memory models allow for simplified hardware and increased performance in
the memory hierarchy at the cost of increased software complexity. In weak
memory models, explicit synchronization is needed to enforce ordering between
different processors. Acquire and release semantics provide a powerful
primitive for expressing only the ordering required for correctness. In this
project, we explore adding load-acquire and store-release instructions to the
RISC-V ISA. We add support to the herd formal memory model, the gem5
cycle-approximate simulator, and the LLVM/Clang toolchain. Because these
instructions do not exist in the RISC-V standard, there is an inherent urgency
to ratify explicit load-acquire/store-release instructions in order to prevent
multiple ABI implementations and ecosystem fragmentation. We found that for
workloads with a high degree of sharing and heavy contention, the impact of
less memory ordering is muted, but our changes successfully encode the
semantics we desire.Comment: 8 pages, 7 figures, 4 listings, class project, ECE 382N-1
Four new T dwarfs identified in PanSTARRS 1 commissioning data
A complete well-defined sample of ultracool dwarfs is one of the key science
programs of the Pan-STARRS 1 optical survey telescope (PS1). Here we combine
PS1 commissioning data with 2MASS to conduct a proper motion search
(0.1--2.0\arcsec/yr) for nearby T dwarfs, using optical+near-IR colors to
select objects for spectroscopic followup. The addition of sensitive far-red
optical imaging from PS1 enables discovery of nearby ultracool dwarfs that
cannot be identified from 2MASS data alone. We have searched 3700 sq. deg. of
PS1 y-band (0.95--1.03 um) data to y19.5 mag (AB) and J16.5
mag (Vega) and discovered four previously unknown bright T dwarfs. Three of the
objects (with spectral types T1.5, T2 and T3.5) have photometric distances
within 25 pc and were missed by previous 2MASS searches due to more restrictive
color selection criteria. The fourth object (spectral type T4.5) is more
distant than 25 pc and is only a single-band detection in 2MASS. We also
examine the potential for completing the census of nearby ultracool objects
with the PS1 3 survey.Comment: 25 pages, 8 figures, 5 table, AJ accepted, updated to comply with
Pan-STARRS1 naming conventio
HIP 38939B: A New Benchmark T Dwarf in the Galactic Plane Discovered with Pan-STARRS1
We report the discovery of a wide brown dwarf companion to the mildly
metal-poor ([Fe/H]=-0.24), low galactic latitude (b = 1.88 deg) K4V star HIP
38939. The companion was discovered by its common proper motion with the
primary and its red optical (Pan-STARRS1) and blue infrared (2MASS) colors. It
has a projected separation of 1630 AU and a near-infrared spectral type of
T4.5. As such it is one of only three known companions to a main sequence star
which have early/mid-T spectral types (the others being HN Peg B and eps Indi
B). Using chromospheric activity we estimate an age for the primary of
900{+1900,-600} Myr. This value is also in agreement with the age derived from
the star's weak ROSAT detection. Comparison with evolutionary models for this
age range indicates that HIP 38939B falls in the mass range 38+/-20 Mjup with
an effective temperature range of 1090+/-60 K. Fitting our spectrum with
atmospheric models gives a best fitting temperature of 1100 K. We include our
object in an analysis of the population of benchmark T dwarfs and find that
while older atmospheric models appeared to over-predict the temperature of the
coolest objects compared to evolutionary models, more recent atmospheric models
provide better agreement.Comment: ApJ, in press. Tiny changes incorporated into final version: added
analysis of likelihood of companionship, clarified the fitting proceedure,
and updated the benchmark analysis to highlight when the quoted evolutionary
models use the atmospheric model they are being compared to as a boundary
conditio
A Prospective Study of Pravastatin in the Elderly at Risk (PROSPER): Screening Experience and Baseline Characteristics
BACKGROUND: PROSPER was designed to investigate the benefits of treatment with pravastatin in elderly patients for whom a typical doctor might consider the prescription of statin therapy to be a realistic option. METHODS: The PROspective Study of Pravastatin in the Elderly at Risk (PROSPER) is a randomised, double blind, placebo-controlled trial to test the hypothesis that treatment with pravastatin (40 mg/day) will reduce the risk of coronary heart disease death, non-fatal myocardial infarction, and fatal or non-fatal stroke in elderly men and women with pre-existing vascular disease or with significant risk of developing this condition. RESULTS: In Scotland, Ireland, and the Netherlands, 23,770 individuals were screened, and 5,804 subjects (2,804 men and 3,000 women), aged 70 to 82 years (average 75 years) and with baseline cholesterol 4.0–9.0 mmol/l, were randomised. Randomised subjects had similar distributions with respect to age, blood pressure, and body mass index when compared to the entire group of screenees, but had a higher prevalence of smoking, diabetes, hypertension, and a history of vascular disease. The average total cholesterol level at baseline was 5.4 mmol/l (men) and 6.0 mmol/l (women). CONCLUSIONS: Compared with previous prevention trials of cholesterol-lowering drugs, the PROSPER cohort is significantly older and for the first time includes a majority of women. The study, having achieved its initial goal of recruiting more than 5,500 elderly high-risk men and women, aims to complete all final subject follow-up visits in the first half of 2002 with the main results being available in the fourth quarter of 2002
National CO2 budgets (2015–2020) inferred from atmospheric CO2 observations in support of the Global Stocktake
Accurate accounting of emissions and removals of CO2 is critical for the planning and verification of emission reduction targets in support of the Paris Agreement. Here, we present a pilot dataset of country-specific net carbon exchange (NCE; fossil plus terrestrial ecosystem fluxes) and terrestrial carbon stock changes aimed at informing countries’ carbon budgets. These estimates are based on "top-down" NCE outputs from the v10 Orbiting Carbon Observatory (OCO-2) modeling intercomparison project (MIP), wherein an ensemble of inverse modeling groups conducted standardized experiments assimilating OCO-2 column-averaged dry-air mole fraction (XCO2) retrievals (ACOS v10), in situ CO2 measurements, or combinations of these data. The v10 OCO-2 MIP NCE estimates are combined with "bottom-up" estimates of fossil fuel emissions and lateral carbon fluxes to estimate changes in terrestrial carbon stocks, which are impacted by anthropogenic and natural drivers. These flux and stock change estimates are reported annually (2015–2020) as both a global 1° × 1° gridded dataset and as a country-level dataset. Across the v10 OCO-2 MIP experiments, we obtain increases in the ensemble median terrestrial carbon stocks of 3.29–4.58 PgCO2 yr-1 (0.90–1.25 PgC yr-1). This is a result of broad increases in terrestrial carbon stocks across the northern extratropics, while the tropics generally have stock losses but with considerable regional variability and differences between v10 OCO-2 MIP experiments. We discuss the state of the science for tracking emissions and removals using top-down methods, including current limitations and future developments towards top-down monitoring and verification systems
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Iconic
This music score was submitted for the Kaleidoscope 2020 Call for Scores, an open access collaboration with the UCLA Music Library
Keltoi client evaluation study.
Keltoi is a therapeutic residential facility within the Eastern region of the Health Service Executive (HSE) that uses an innovative systemic model to provide an 8 week rehabilitation programme for former drug users. This report describes the results of a follow-up evaluation survey of 94 successive clients who attended the programme and who were between 1-and 3-years post-discharge. 100 attendees of the Keltoi programme who were (minimum) 1-year post-completion of the residential component of their treatment agreed to take part in the study, whereby the four page Maudsley Addiction Profile (MAP) was completed, as was a short qualitative interview. The cohort was recruited on a temporal basis; the first study participant was discharged on 18 November 2002, the one hundredth was discharged on 30 August 2004. This is a non-random cross-sectional field-study of a sample of 67% (100/150) of the total number of Keltoi clients to that date.
Of the 80 clients on whose responses analysis was carried out, 51% were abstinent from all illicit drugs and alcohol in 30 days pre-interview; 60% were abstinent from all illicit drugs but had consumed alcohol in the 30 day pre-interview period; and 65% were abstinent from all substances excluding alcohol and cannabis in the same period. Of the 40% of individuals who were using substances other than alcohol, only five (5.4%) were injecting drugs. Cross-sectional outcomes are also presented with respect to crime, health and risk behaviours, social and personal functioning and employment. In general, abstinent clients (including those who were abstinent excluding alcohol) reported minimal criminal activity and positive outcomes in relation to the other measures
Marketing and the law
Examines the legal controls imposed on the manufacturing, labelling, packaging, distribution, promotion, pricing and retailing of goods and services. The book aims to provide a text appropriate for practitioners and students of marketing and focuses on the impact of the laws on the marketing of products
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