Real-time systems need to be built out of tasks for which the worst-case execution time is known. To enable accurate estimates of worst-case execution time, some researchers propose to build processors that simplify that analysis. These architectures are called precision-timed machines or time-predictable architectures. However, what does this term mean? This paper explores the meaning of time predictability and how it can be quantified. We show that time predictability is hard to quantify. Rather, the worst-case performance as the combination of a processor, a compiler, and a worst-case execution time analysis tool is an important property in the context of real-time systems. Note that the actual software has implications as well on the worst-case performance. We propose to define a standard set of benchmark programs that can be used to evaluate a time-predictable processor, a compiler, and a worst-case execution time analysis tool. We define worst-case performance as the geometric mean of worst-case execution time bounds on a standard set of benchmark programs.

Excavations at Tiaotou reveal evidence for cultural continuity through the late third to the mid first millennia BC. This research explores shifts in subsistence, production and ritual at Tiaotou, and the emergence of the Pishan-Tiaotou Culture (1200–1000 BC). Tiaotou/Pishan-Tiaotou represents a missing link among Taihu Lake archaeological cultures and contributes to our knowledge of complex political formations and cultural change in Bronze Age southern China.

The upsurge in the number of people affected by the COVID-19 is likely to lead to increased rates of emotional trauma and mental illnesses. This article systematically reviewed the available data on the benefits of interventions to reduce adverse mental health sequelae of infectious disease outbreaks, and to offer guidance for mental health service responses to infectious disease pandemic. PubMed, Web of Science, Embase, PsycINFO, WHO Global Research Database on infectious disease, and the preprint server medRxiv were searched. Of 4278 reports identified, 32 were included in this review. Most articles of psychological interventions were implemented to address the impact of COVID-19 pandemic, followed by Ebola, SARS, and MERS for multiple vulnerable populations. Increasing mental health literacy of the public is vital to prevent the mental health crisis under the COVID-19 pandemic. Group-based cognitive behavioral therapy, psychological first aid, community-based psychosocial arts program, and other culturally adapted interventions were reported as being effective against the mental health impacts of COVID-19, Ebola, and SARS. Culturally-adapted, cost-effective, and accessible strategies integrated into the public health emergency response and established medical systems at the local and national levels are likely to be an effective option to enhance mental health response capacity for the current and for future infectious disease outbreaks. Tele-mental healthcare services were key central components of stepped care for both infectious disease outbreak management and routine support; however, the usefulness and limitations of remote health delivery should also be recognized.

OBJECTIVES/SPECIFIC AIMS: The serotonin receptor 6 (5-HT6) is a potential therapeutic target given its distribution in brain regions that are important in depression, anxiety, and cognition. This study sought to investigate the effects of age on 5-HT6 receptor availability using 11C GSK215083, a PET ligand with affinity for 5-HT6 in the striatum and 5-HT2A in the cortex. METHODS/STUDY POPULATION: In total, 28 healthy male subjects (age range: 23–52 years) were scanned with 11C-GSK215083 on the HR+PET scanner. Time-activity curves in regions-of-interest were fitted with multilinear analysis-1 method. Binding potentials (BPND) were calculated using cerebellum as the reference region and corrected for partial volume effects. RESULTS/ANTICIPATED RESULTS: In 5-HT6 rich areas, regional 11C-GSK215083 displayed a negative correlation between BPND and age in the caudate (r=−0.41, p=0.03) (14% change per decade), and putamen (r=−0.30, p=0.04) (11% change per decade), but not in the ventral striatum and pallidum. Negative correlation with age was also seen in cortical regions (r=−0.41, p=0.03) (7% change per decade), consistent with the literature on 5-HT2A availability. DISCUSSION/SIGNIFICANCE OF IMPACT: This is the first in vivo study in humans to examine the effect of age on 5-HT6 receptor availability. The study demonstrated a significant age-related decline in 5-HT6 availability (BPND) in the caudate and putamen.

The Ebinur lake basin, Tien Shan, China, was described in the early 20th century as the ‘Green Labyrinth’. This relatively productive area supports agriculture and stands in contrast to the regional aridity. Glacier melt runoff is an important source of water for this arid region and has played a significant role in its economic development. However, over the past 40 years the ecology and environment of the region have seriously degenerated due to human activity and climate change. To investigate changes in glacier water supply, measurements from two reference glaciers were performed and used to validate satellite data and historical data for glaciers in the water catchment. Variability in regional glacier total area and volume over the past 40 years was reconstructed from historical documents, aerial photographs and remote-sensing data. Our investigations of 446 glaciers showed that from 1964 to 2004 the total glacier area decreased by 14.7% (0.4% a–1), corresponding to an estimated volume change of 20.5%. During this period, the most dramatic decrease in glacier area corresponded to a rapid rise in temperature. This reduction in glacier area is accelerating and impacting the future sustainability of the region’s water resources.

The integration of dissimilar materials is highly desirable for many different types of device applications but often challenging to achieve in practice. The unrivalled imaging capabilities of the aberration-corrected electron microscope enable enhanced insights to be gained into the atomic arrangements across heterostructured interfaces. This paper provides an overview of our recent observations of oxide-semiconductor heterostructures using aberration-corrected high-angle annular-dark-field and large-angle bright-field imaging modes. The perovskite oxides studied include strontium titanate, barium titanate, and strontium hafnate, which were grown on Si(001) and/or Ge(001) substrates using the techniques of molecular-beam epitaxy or atomic-layer deposition. The oxide layers displayed excellent crystallinity and sharp, abrupt interfaces were observed with no sign of any amorphous interfacial layers. The Ge(001) substrate surfaces invariably showed both 1× and 2× periodicity consistent with preservation of the 2 × 1 surface reconstruction following oxide growth. Overall, the results augur well for the future development of functional oxide-based devices integrated on semiconductor substrates.

This study provides new insight into the effectiveness of different knowledge acquisition strategies for organizations at different positions in a production network. Component specialists and systems integrators require a different knowledge repertoire in terms of knowledge depth and knowledge breadth. We show that a greater reliance on inter-organizational partnering than on intra-organizational acquiring is effective in the acquisition of knowledge breadth rather than knowledge depth. And the positive effect of a greater reliance on inter-organizational partnering on knowledge breadth is particularly strong for system integrators.

This paper synthesizes and extends the literature on multivariate two-part regression modelling, with an emphasis on actuarial applications. To illustrate the modelling, we use data from the US Medical Expenditure Panel Survey to explore expenditures that come in two parts. In the first part, zero expenditures correspond to no payments for health care services during a year. For the second part, a positive expenditure corresponds to the payment amount, a measure of utilization. Expenditures are multivariate, the five components being (i) office-based, (ii) hospital outpatient, (iii) emergency room, (iv) hospital inpatient, and (v) home health expenditures. Not surprisingly, there is a high degree of association among expenditure types and so we utilize models that account for these associations. These models include multivariate binary regressions for the payment type and generalized linear models with Gaussian copulas for payment amounts.

As anticipated, the strong associations among expenditure types allow us to establish significant model differences on an in-sample basis. Despite these strong associations, we find that commonly used statistical measures perform similarly on a held-out validation sample. In contrast, out-of-sample risk measures used by actuaries reveal differences in the association among expenditure types.

This paper details the development of a technique to improve the minority carrier lifetime of 4H-SiC thick (≥ 100 μm) n-type epitaxial layers through multiple thermal oxidations. A steady improvement in lifetime is seen with each oxidation step, improving from a starting ambipolar carrier lifetime of 1.09 µs to 11.2 µs after 4 oxidation steps and a high-temperature anneal. This multiple-oxidation lifetime enhancement technique is compared to a single high-temperature oxidation step, and a carbon implantation followed by a high-temperature anneal, which are traditional ways to achieve high ambipolar lifetime in 4H-SiC n-type epilayers. The multiple oxidation treatment resulted in a high minimum carrier lifetime of 6 µs, compared to < 2 µs for other treatments. The implications of lifetime enhancement to high-voltage/high-current 4H-SiC power devices are also discussed.

III-V compounds such as InGaAs, InAs, InSb have great potential for future low power high speed devices (such as MOSFETs, QWFETs, TFETs and NWFETs) application due to their high carrier mobility and drift velocity. The development of good quality high k gate oxide as well as high k/III-V interfaces is prerequisite to realize high performance working devices. Besides, the downscaling of the gate oxide into sub-nanometer while maintaining appropriate low gate leakage current is also needed. The lack of high quality III-V native oxides has obstructed the development of implementing III-V based devices on Si template. In this presentation, we will discuss our efforts to improve high k/III-V interfaces as well as high k oxide quality by using chemical cleaning methods including chemical solutions, precursors and high temperature gas treatments. The electrical properties of high k/InSb, InGaAs, InSb structures and their dependence on the thermal processes are also discussed. Finally, we will present the downscaling of the gate oxide into sub-nanometer scale while maintaining low leakage current and a good high k/III-V interface quality.