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The current perspective of the PA 1957 gas well pillar study and its implications for longwall gas well pillars

International Journal of Mining Science and Technology 2021年第1期31卷 117-126页

作者： Peter Zhang Daniel Su chris Mark CDC NIOSH Pittsburgh Mining Research DivisionPittsburghPA 15236USA Mine Safety and Health Administration PittsburghPA 15217USA

Many states rely upon the Pennsylvania 1957 Gas Well Pillar Study to evaluate the coal barrier surrounding gas *** study included 77 gas well failure cases that occurred in the Pittsburgh and Freeport coal seams over a 25-year *** the time,coal was mined using the room-and-pillar mining method with full or partial pillar recovery,and square or rectangle pillars surrounding the gas wells were left to protect the *** study provided guidelines for pillar sizes under different overburden depths up to 213 m(700 ft).The 1957 study has also been used to determine gas well pillar sizes in longwall mines since longwall mining began in the 1970 *** original study was developed for room-and-pillar mining and could be applied to gas wells in longwall chain pillars under shallow ***,under deep cover,severe deformations in gas wells have occurred in longwall chain ***,with a better understanding of coal pillar mechanics,new insight into subsidence movements induced by retreat mining,and advances in numerical modeling,it has become both critically important and feasible to evaluate the adequacy of the 1957 study for longwall gas well *** this paper,the data from the 1957 study is analyzed from a new perspective by considering various factors,including overburden depth,failure location,failure time,pillar safety factor(SF),and floor *** pillar SF and floor pressure are calculated by considering abutment pressure induced by full pillar recovery.A statistical analysis is performed to find correlations between various factors and helps identify the most significant factors for the stability of gas wells influenced by retreat *** analyzing the data from the 1957 study,the guidelines for gas well pillars in the 1957 study are evaluated for their adequacy for roomand-pillar mining and their applicability to longwall *** modeling is used to model the stability of gas wells by quantifying the mining-induced s

关键词： Gas well pillar Pennsylvania 1957 gas well pillar study Room-and-pillar mining Longwall mining

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Spinal Analgesia with Intrathecal Morphine versus Conventional Analgesia after Laparoscopic Colectomy: A Retrospective Cohort Study

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Open Journal of Anesthesiology 2024年第7期14卷 159-174页

作者： Lionel Diyamona Manon Colin Marc Léone Laurent Zieleskiewicz Joseph Nsiala Wilfrid Mbombo Rachel Mbala Bruno Pastene chris Nsituavibidila Dan Kankonde Gracia Likinda Jean Claude Mubenga Khazy Anga Noelly Mukuna christel Isengingo Department of Anaesthesia and Intensive Care University Clinics of Kinshasa University of Kinshasa Kinshasa Democratic Republic of the Congo Department of Anaesthesia and Intensive Care Marseilles Nord Hospital Marseille France General Hospital of Kinshasa ex Mama Yemo Kinshasa Democratic Republic of the Congo Department of Anaesthesia and Intensive Care Monkole Hospital Centre Kinshasa Democratic Republic of the Congo

Objective: Postoperative pain (POP) following abdominal surgery can vary from a few hours to several days. This acute, unrelieved pain can become chronic, requiring patients to take analgesics on an almost daily basis for comfort. Analgesia using general opioids has many side effects and intrathecal morphine is a good alternative. This study was conducted to evaluate the efficacy of intrathecal morphine (ITM) versus conventional analgesia in the management of postoperative pain in colectomy performed by laparoscopic surgery. Methods: Cohort study conducted at the Hôpital Nord in Marseille, from 01 January to 31 July 2021 in patients aged at least 18 years undergoing anaesthesia for scheduled colectomy by laparoscopic surgery. The primary endpoint was postoperative pain intensity and the secondary endpoints were morphine consumption, treatment side effects and length of hospital stay. Statistical analysis was performed using XLSTAT software. Results: We included 193 patients: 131 in the control group (conventional analgesia) and 62 in the ITM group. We observed: a significant decrease in pain (assessed by numerical scale) in favour of the ITM group in the post-anaesthetic care room, i.e. 3 (±4) vs 1 (±2), p 0 and H2: 2 (±2) vs. 1 (±2);p Conclusion: These results suggest that intrathecal morphine (ITM) in laparoscopic colectomy provides effective postoperative analgesia with low morphine consumption, and a reduction in morphine side-effects compared with conventional analgesia.

关键词： Intrathecal Morphine Colectomy Laparoscopy Conventional Analgesia

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Professor William R. Cullen and arsenic chemistry

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Journal of Environmental Sciences 2016年第11期28卷 1-6页

作者： X.chris Le Division of Analytical and Environmental Toxicology Department of Laboratory Medicine and Pathology University of Alberta

This special issue of the Journal of Environmental Sciences honors Professor William *** for his outstanding contributions to synthetic chemistry,environmental chemistry,microbiology,and toxicology of arsenic and its ... 详细信息

关键词： arsenic fitting contributions diverse outstanding Royal expertise interested grateful friendly

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Nonlinear Control of Magnetically-geared Drive-trains

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International Journal of Automation and computing 2013年第4期10卷 319-326页

作者： Ryan Montague chris Bingham Department of Computer Science University of York School of Engineering University of Lincoln

The paper considers certain impedimental issues related to the use of magnetic gearbox and magnetic coupling technologies in high performance servo control systems. A prototype magnetic coupling is used as a basis for demonstrating that the underlying torque transfer characteristic is significantly nonlinear when transmitted torque approaches the maximum designed pull-out torque of the device. It is shown that linear controllers for speed control proportional plus integral （PI） and position control proportional plus derivative （PD） result in acceptable performance provided the magnetic coupling operates below 80 % of designed pull-out torque. To fully compensate for the inherent nonlinearity of the torque transfer characteristic, feedback linearizing control laws and state transformations are derived resulting in exactly linear input-output characteristic for position and speed control of magnetically-geared drive-trains. With the addition of state feedback, the closed-loop dynamics for both position and speed control of a magnetically-geared drive-train can be designed to satisfy the integral of time multiplied by absolute error （ITAE） optimized linear response for a step input. Outstanding results are demonstrated through simulation and experimental real-time implementation on a demonstrator magnetically-geared drive-train.

关键词： Magnetic gears magnetic couplings linear control nonlinear control feedback linearization.

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The human and mouse sex-determining SRY genes repress the Rspo1/β-catenin signaling

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Journal of Genetics and Genomics 2009年第4期36卷 193-202页

作者： Yun-Fai chris Lau Division of Cell and Developmental Genetics Department of Medicine VA Medical Center University of CaliforniaSan Francisco CA 94121 USA

The sex-determining region Y （SRY） is the gene on the Y chromosome responsible for switching on male sex determination during mammalian embryogenesis. In its absence, ovaries develop in the embryo. Hence, ovarian determination and differentiation is considered to be a default, or passive, developmental pathway. Recently this classical paradigm of sex determination has been challenged with the discovery of the R-spondin 1 （RSPO1） as an active ovarian determinant. Mutations of RSPO1 cause a female-to-male sex reversal. RSPO1 synergizes with WNT4 in activating an ovarian development in the bipotential gonad via the canonical Wnt signaling. Early studies showed that SRY represses such Wnt signaling, but also generated discrepancies on whether only mouse Sry is capable of inhibiting such Wnt signaling and whether both human and mouse SRY proteins are able to interact with β-catenin, the intracellular messenger responsible for executing the Wnt signals. Our studies show that both human SRY and mouse Sry are capable of repressing the Rspol/Wnt/β-catenin signaling. However, the repression activities vary among different SRY/Sry proteins and paradoxically related to the presence and/or size of an acidic/glutamine-rich domain. The HMG box of human SRY could bind directly to β-catenin while the mouse Sry binds to β-catenin via its HMG box and glutamine-rich domain. The results clarify some of the initial discrepancies, and raise the possibility that SRY interacts with β-catenin in the nucleus and represses the transcriptional activation of the Rspol/Wnt target genes involved in ovarian determination, thereby switching on testis determination.

关键词： SRY sex determination R-spondin 1 canonical Wnt signaling β-catenin protein interaction

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Corundum formation by metasomatic reactions in Archean metapelite,SW Greenland:Exploration vectors for ruby deposits within high-grade greenstone belts

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Geoscience Frontiers 2018年第3期9卷 727-749页

作者： chris Yakymchuk Kristoffer Szilas Earth and Environmental Sciences University of Waterloo200 University Ave WestWaterlooOntario N2L 3G1Canada Geological Survey of Denmark and Greenland(GEUS) Oter Voldgade 101350 Copenhagen KDenmark

Corundum(ruby-sapphire) is known to have formed in situ within Archean metamorphic rocks at several localities in the North Atlantic Craton of Greenland. Here we present two case studies for such occurrences:(1) Maniitsoq region(Kangerdluarssuk), where kyanite paragneiss hosts ruby corundum, and(2)Nuuk region(Stor?), where sillimanite gneiss hosts ruby corundum. At both occurrences, ultramafic rocks(amphibole-peridotite) are in direct contact with the ruby-bearing zones, which have been transformed to mica schist by metasomatic reactions. The bulk-rock geochemistry of the ruby-bearing rocks is consistent with significant depletion of SiO_2 in combination with addition of Al_2O_3, MgO, K_2O,Th and Sr relative to an assumed aluminous precursor metapelite. Phase equilibria modelling supports ruby genesis from the breakdown of sillimanite and kyanite at elevated temperatures due to the removal of SiO_2. The juxtaposition of relatively silica-and aluminum-rich metasedimentary rocks with low silica ultramafic rocks established a chemical potential gradient that leached/mobilized SiO_2 allowing corundum to stabilize in the former rocks. Furthermore, addition of Al_2O_3 via a metasomatic reaction is required, because Al/Ti is fractionated between the aluminous precursor metapelites and the resulting corundum-bearing mica schist. We propose that Al was mobilized either by complexation with hydroxide at alkaline conditions, or that Al was transported as K-Al-Si-O polymers at deep crustal *** three main exploration vectors for corundum within Archean greenstone belts are:(1) amphiboliteto granulite-facies metamorphic conditions,(2) the juxtaposition of ultramafic rocks and aluminous metapelite, and(3) mica-rich reactions zones at their interface.

关键词： Ultramafic rocks Kyanite Sillimanite Metasomatism Pseudosection Desilicification

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Burden sharing for CDR: balancing fair liability with feasibility

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National Science Review 2023年第12期10卷 47-48页

作者： chris D.Jones Met Office Hadley Centre

The basics are clear:climate is changing,it is caused by human activity and it is affecting everyone and everywhere now[1]. The good news is that we know what to do about it—we can stop global temperatures rising further if we stop emitting greenhouse gases. But because some sectors (such as agriculture or aviation)will have ongoing ‘hard-to-abate’ emissions,

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COP27 climate change conference:urgent action needed for Africa and the world

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Stroke & Vascular Neurology 2023年第3期8卷 178-180页

作者： chris Zielinski UK Health Alliance on Climate Change LondonUK

Wealthy nations must step up support for Africa and vulnerable countries in addressing past,present and future impacts of climate change The 2022 report of the Intergovernmental Panel on Climate Change paints a dark picture of the future of life on earth,charac-terised by ecosystem collapse,species extinc-tion and climate hazards such as heatwaves and floods.

关键词： climate floods action

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Time to treat the climate and nature crisis as one indivisible global health emergency

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Family Medicine and Community Health 2023年第4期11卷 1-3页

作者： chris Zielinski Centre for Global Health University of WinchesterWinchesterUK

Over 200 health journals call on the United Nations(UN),political leaders and health professionals to recognise that climate change and biodiversity loss are one indivisible crisis and must be tackled together to pres... 详细信息

关键词： preserve global divisible

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Identification of high-dielectric constant compounds from statistical design

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npj Computational Materials 2022年第1期8卷 1396-1405页

作者： Abhijith Gopakumar Koushik Pal chris Wolverton Department of Materials Science and Engineering Northwestern University2220 Campus DriveEvanstonIL60208USA

The discovery of high-dielectric materials is crucial to increasing the efficiency of electronic devices and ***,we report three previously unexplored materials with very high dielectric constants(69<ϵ<101)and large b... 详细信息

关键词： dielectric high constant

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