Sleep quality as a mediator of problematic smartphone use and clinical health symptoms

Background and aims Although smartphone use brings many benefits for adolescents, it is also associated with many serious health problems. This study examined the relationship between problematic smartphone use (PSU) and clinical health symptoms (e.g., body dysfunction) and the mediating effects of sleep quality on this relationship in adolescents. Methods Participants in this cross-sectional survey were 686 middle- and high-school students (girls = 55.7%, Mage = 12.98 ± 1.38 years). Participants completed self-report measures of PSU, sleep quality, and physical symptoms. Correlation analyses and structural equation modeling between adolescents’ PSU and the variables of interest were conducted. Results This study indicated that there was a significant positive correlation between PSU and health symptoms. Furthermore, sleep quality mediated the relationship between PSU and health symptoms. Discussion and conclusions Findings suggest that to promote health and wellness in adolescents, individuals should be encouraged to place boundaries on smartphone use, especially at bedtime. Reducing adolescents’ exposure to smartphone use in this way may hold promise for improving the efficacy of PSU prevention efforts for adolescents

Petuum: A New Platform for Distributed Machine Learning on Big Data

What is a systematic way to efficiently apply a wide spectrum of advanced ML programs to industrial scale problems, using Big Models (up to 100s of billions of parameters) on Big Data (up to terabytes or petabytes)? Modern parallelization strategies employ fine-grained operations and scheduling beyond the classic bulk-synchronous processing paradigm popularized by MapReduce, or even specialized graph-based execution that relies on graph representations of ML programs. The variety of approaches tends to pull systems and algorithms design in different directions, and it remains difficult to find a universal platform applicable to a wide range of ML programs at scale. We propose a general-purpose framework that systematically addresses data- and model-parallel challenges in large-scale ML, by observing that many ML programs are fundamentally optimization-centric and admit error-tolerant, iterative-convergent algorithmic solutions. This presents unique opportunities for an integrative system design, such as bounded-error network synchronization and dynamic scheduling based on ML program structure. We demonstrate the efficacy of these system designs versus well-known implementations of modern ML algorithms, allowing ML programs to run in much less time and at considerably larger model sizes, even on modestly-sized compute clusters.Comment: 15 pages, 10 figures, final version in KDD 2015 under the same titl

Numerical analysis on the centralization effect of improved horizontal well casing centralizer

Horizontal well technology is a promising method for oil and gas development. During cementing operations in horizontal wells, it was found that conventional casing centralizers could not meet the requirements for casing cementing in expanded wellbores. Therefore, a new type of casing centralizer needs to be designed for horizontal well sections that have undergone enlargement. By analyzing the most common materials currently used, 45 steel was selected for the spring leaf of the novel casing centralizer. To evaluate the centralization effect of the horizontal well casing centralizer, a casing centralization degree evaluation function was established, and a wellbore-centralizer mechanical model was proposed using the finite element method to simulate the working conditions of the centralizer spring leaf in ϕ215.9 and ϕ311.2 mm well sections. On this basis, a wellbore-centralizer-casing coupling model that does not consider the effect of wellbore fluid on the casing was established to simulate the centralization characteristics of the new casing centralizer and traditional centralizer under different wellbore sizes. Simulation results show that the average casing centralization degree of the new centralizer is 85.53%, while that of the traditional centralizer is 55.58%. That is, the horizontal well casing centralizer can maintain a good centralization effect on the casing string

Analysis of the Factors that Influence Diagenesis in the Terminal Fan Reservoir of Fuyu Oil Layer in the Southern Songliao Basin, Northeast China

The diagenesis mechanism and the physical properties of a terminal fan reservoir are determined by nuclear magnetic resonance (NMR), X-ray diffraction and scanning electron microscopy. The main provenance directions are NE and SE, and the two oppositely directed fans converge to form a small catchment basin. The mudstone color is red or purplish red, which accounts for 60% of the total rock. The sandstones are lithic-feldspar sandstones and feldspar-lithic sandstones, with a smaller quartz component relative to the adjacent sandstone formations. The reservoir mainly consists of intergranular pores (51%), intragranular pores (22%), corrosion pores (20%), micro-fractures (5%) and clay matrix pores (2%). The porosity of the reservoir is only 13%, and the throats are fine with high displacement pressure. The diagenetic processes included compaction, cementation, replacement, and dissolution, and the most influential factor on the reservoir porosity was compaction. The detrital rock cement mainly consists of clay minerals (48%), quartz (23%), carbonate (19%), feldspar (7%) and dawsonite (3%). Among them, the mixed I/S layer has the most content and the most important cementation. In addition, a small amount of dawsonite is found in the pores of the sandstone, which is a unique mineral that is related to the background of inorganic CO2. The main diagenesis factors that affected this sandstone’s porosity were compaction, early quartz overgrowth and calcite cementation, which reduced the porosity from 40% to approximately 8%. Although dissolution and fracture increased the porosity (from 8% to 26%), clay- and carbonate-mineral cementation during the late diagenesis period had a dramatic effect, forming a typical low-porosity and low-permeability reservoir