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Importance of proper renormalization scale-setting for QCD testing at colliders

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Frontiers of physics 2016年第1期11卷 27-37页

作者： Xing-Gang Wu Sheng-Quan Wang stanley j. Brodsky Department of Physics Chongqing University Chongqing 401331 China School of Science Guizhou Minzu University Guiyang 550025 China SLA C National Accelerator Laboratory Stanford University Stanford CA 94039 USA

A primary problem affecting perturbative quantum chromodynamic （pQCD） analyses is the lack of a method for setting the QCD running-coupling renormalization scale such that maximally precise fixed-order predictions for physical observables are obtained. The Principle of Maximum Conformality （PMC） eliminates the ambiguities associated with the conventional renormalization scale-setting procedure, yielding predictions that are independent of the choice of renormalization scheme. The QCD coupling scales and the effective number of quark flavors are set orderby-order in the pQCD series. The PMC has a solid theoretical foundation, satisfying the standard renormalization group invariance condition and all of the self-consistency conditions derived from the renormalization group. The PMC scales at each order are obtained by shifting the arguments of the strong force coupling constant as to eliminate all non-conformal {βi} terms in the pQCD series. The {βi} terms are determined from renormalization group equations without ambiguity. The correct behavior of the running coupling at each order and at each phase-space point can then be obtained. The PMC reduces in the Nc → 0 Abelian limit to the Gell-Mann-Low method. In this brief report, we summarize the results of our recent application of the PMC to a number of collider processes, emphasizing the generality and applicability of this approach. A discussion of hadronic Z decays shows that, by applying the PMC, one can achieve accurate predictions for the total and separate decay widths at each order without scale ambiguities. We also show that, if one employs the PMC to determine the top-quark pair forward-backward asymmetry at the next-to-next-to-leading order level, one obtains a comprehensive, self-consistent pQCD explanation for the Tevatron measurements of the asymmetry. This accounts for the ＂increasing-decreasing＂ behavior observed by the DO collaboration for increasing tt invariant mass. At lower energies, the angular d

关键词： QCD proper renormalization scale-setting PMC high-energy colliders

Update on risk scoring systems for patients with upper gastrointestinal haemorrhage

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World j.urnal of Gastroenterology 2012年第22期18卷 2739-2744页

作者： Adrian j.stanley Gastrointestinal Unit Glasgow Royal Infirmary Glasgow G4 OSF United Kingdom

Upper gastrointestinal haemorrhage (UGIH) remains a common medical emergency worldwide. It is increasingly recognised that early risk assessment is an important part of management, which helps direct appropriate patient care and the timing of endoscopy. Several risk scores have been developed, most of which include endoscopic findings, although a minority do not. These scores were developed to identify various end-points including mortality, rebleeding or clinical intervention in the form of transfusion, endoscopic therapy or surgery. Recent studies have reported accurate identification of a very low risk group on presentation, using scores which require simple clinical or laboratory parameters only. This group may not require admission, but could be managed with early out-patient endoscopy. This article aims to describe the existing pre- and post-endoscopy risk scores for UGIH and assess the published data comparing them in the prediction of outcome. Recent data assessing their use in clinical practice, in particular the early identification of low-risk patients, are also discussed.

关键词： Upper gastrointestinal haemorrhage Bleeding Endoscopy Risk assessment Scoring systems Bla-tchford Rockall

Concordance among indices of intrinsic brain function： Insights from inter-individual variation and temporal dynamics

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Science Bulletin 2017年第23期62卷 1572-1584页

作者： Chao-Gan Yan Zhen Yang stanley j. Colcombe Xi-Nian Zuo Michael P. Milham CAS Key Laboratory of Behavioral Science Institute of Psychology Beijing 100101 China Departrnent of Psychology University of Chinese Academy of Sciences Beijing 100101 China Magnetic Resonance Imaging Research Center Institute of Psychology Chinese Academy of Sciences Beijing 100101 China center for Lifespan Innovation of Mind and Brain Institute of Psychology Chinese Academy of Sciences Beijing China Nathan Kline Institute for Psychiatric Research Orangeburg NY 10962 USA Department of Child and Adolescent Psychiatry NYU Langone Medical Center School of Medicine New York NY 10016 USA Center for Neuromodulation in Depression and Stress Department of Psychiatry Perelman School of Medidne University of Pennsylvania Philadelphia PA 19104 USA Child Mind Institute New York NY 10022 USA

Various resting-state fMRI(R-fMRI) measures have been developed to characterize intrinsic brain activity. While each of these measures has gained a growing presence in the literature, questions remain regarding the common and unique aspects these indices capture. The present work provided a comprehensive examination of inter-individual variation and intra-individual temporal variation for commonly used measures, including fractional amplitude of low frequency fluctuations, regional homogeneity,voxel-mirrored homotopic connectivity, network centrality and global signal correlation. Regardless of whether examining intra-individual or inter-individual variation, we found that these definitionally distinct R-fMRI indices tend to exhibit a relatively high degree of covariation, which doesn't exist in phase randomized surrogate data. As a measure of intrinsic brain function, concordance for R-fMRI indices was negatively correlated with age across individuals(i.e., concordance among functional indices decreased with age). To understand the functional significance of concordance, we noted that higher concordance was generally associated with higher strengths of R-fMRI indices, regardless of whether looking through the lens of inter-individual(i.e., high vs. low concordance participants) or intra-individual(i.e., high *** concordance states identified via temporal dynamic analyses) differences. We also noted a linear increase in functional concordance together with the R-fMRI indices through the scan, which may suggest a decrease in arousal. The current study demonstrated an enriched picture regarding the relationship among the R-fMRI indices, as well as provided new insights in examining dynamic states within and between individuals.

关键词： Resting-state fMRI Intrinsic brain activity Concordance Temporal dynamics Inter-individual variation

Analysis of drying and saturating natural gypsum samples for mechanical testing

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j.urnal of Rock Mechanics and Geotechnical Engineering 2019年第2期11卷 219-227页

作者： Mohammadhossein Sadeghiamirshahidi stanley j.Vitton Department of Civil and Environmental Engineering Michigan Technological University

The stability of underground abandoned gypsum mines is dependent on the gypsum pillar's strength,and most abandoned mines are in a fully saturated condition. Moisture affects the strength of gypsum and is therefore commonly measured when testing rock strength. For most rocks, this is a simple task of weighing the rock's mass before and after oven-heating at a specified temperature and duration. For natural gypsum, however, this is not a straightforward process. Heating natural gypsum can result in dehydration and transformation of gypsum to hemihydrate and anhydrite, thus changing the physical characteristics of the gypsum such as its particle density which in turn affects the moisture content and strength measurements. To prevent transformation when determining the moisture content of gypsum,the American Society for Testing Materials(ASTM) recommends lowering the drying temperature from 110℃ to 60℃ . To investigate the temperature at which gypsum transforms to hemihydrate, we used a helium pycnometer to measure the particle densities of gypsum, hemihydrate and anhydrite. In this research, we suggest that a higher drying temperature of 80℃ can be used for drying gypsum without transforming gypsum to hemihydrate. Further, preparing saturated samples for mechanical testing,which is required in stability analyses of abandoned mines, is challenging due to the dissolution of gypsum when placed in water. To address this problem, we investigated the following methods to saturate gypsum cores taking into account the solubility of gypsum:(1) water immersion,(2) vacuum saturation, and(3) improved vacuum saturation. The research indicates that all the three methods are acceptable but they should be conducted using a saturated gypsum-water solution to minimize dissolution. Further, the research found that the improved vacuum saturation method saturated the test samples within 24 h, while duration of 30 h was required for the other two methods.

关键词： Gypsum-hemihydrate-anhydrite transformation Dehydration Rock core saturation Moisture content Helium pycnometer

Mechanical properties of Michigan Basin’s gypsum before and after saturation

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j.urnal of Rock Mechanics and Geotechnical Engineering 2019年第4期11卷 739-748页

作者： Mohammadhossein Sadeghiamirshahidi stanley j.Vitton Department of Civil and Environmental Engineering Michigan Technological University

The stability analysis of an abandoned underground gypsum mine requires the determination of the mine pillar’s *** is especially important for flooded abandoned mines where the gypsum pillars become saturated and are subj.cted to dissolution after ***,mine pillars are subj.cted to blast vibrations that generate some level of macro- and *** samples of gypsum must,therefore,simulate these conditions as close as *** this research,the strength of gypsum is investigated in an as-received saturated condition using uniaxial compressive strength (UCS),Brazilian tensile strength (BTS) and point load index (PLI) *** scale effect was investigated and new correlations were derived to describe the effect of sample size on both UCS and BTS under dry and saturated *** of blasting on these parameters were observed and the importance of choosing the proper samples was ***,correlations were derived for both compressive and tensile strengths under dry and saturated conditions from the PLI test results,which are commonly used as a simple substitute for the indirect determination of UCS and BTS.

关键词： Uniaxial compressive strength (UCS) Brazilian tensile strength (BTS) Point load index (PLI) Scale effect Michigan Basin's gypsum

Intrinsic charm production of doubly charmed baryons:Collider vs. fixed-target

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Science China(Physics,Mechanics & Astronomy) 2020年第2期63卷 29-31页

作者： Ramona Vogt stanley j.Brodsky 无 Nuclear and Chemical Sciences Division Lawrence Livermore National LaboratoryLivermoreCA 94551USA Department of Physics University of CaliforniaDavisCA 95616USA Stanford Linear Accelerator Center Stanford UniversityStanfordCA 94309USA

The LHCb Collaboration has measured the doubly charmed baryon,■^++cc(ucc),through two different decay channels[1,2]in p+p collisions at center-of-mass energies of 7,8 and 13 *** they have performed similar searches for the doubly charmed baryon ■^+cc(dcc),it has not yet been observed by LHCb[3].However,the fixed-target experiment,SELEX,at Fermilab,reported the observation of the ■^+cc in two different decay channels with a 600 GeV charged hyperon beam[4,5].The beam was composed of an admixture of π^±,p,p components as well as the Σ^- *** discussion has arisen over the fact that the fixed-target observations have not been easily reproduced by the collider experiments at higher energies,where one might have expected the production rates to be much higher due to the orders of magnitude increase in the center of mass energy with LHCb.

关键词： doubly fixed decay

Endoscopic ultrasound-guided elastography in the nodal staging of oesophageal cancer

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World j.urnal of Gastroenterology 2012年第9期18卷 889-895页

作者： Stuart Paterson Fraser Duthie Adrian j.stanley Department of Gastroenterology Forth Valley Royal Hospital Department of Pathology Glasgow Royal Infirmary Department of Gastroenterology Glasgow Royal Infirmary

AIM： To assess quantitative endoscopic ultrasound （EUS）- guided elastography in the nodal staging of oesophago- gastric cancers.METHODS： This was a single tertiary centre study as- sessing 50 patients with established oesophago-gastric cancer undergoing EUS-guided fine needle aspiration biopsy （FNAB） of lymph nodes between j.ly 2007 and j.ly 2009. EUS-guided elastography of lymph nodes was performed before EUS-FNAB. Standard EUS charac- teristics were also described. Cytological determination of whether a lymph node was malignant or benign was used as the gold standard for this study. Comparisons of elastography and standard EUS characteristics were made between the cytologically benign and malignant nodes. The main outcome measure was the accuracy of elastography in differentiating between benign and malignant lymph nodes in oesophageal cancers.

关键词： Endoscopic ultrasound Oesophageal cancerLymph nodes Elastography Tumour staging

Female mate choice and the potential for ornament evolution in túngara frogs Physalaemus pustulosus

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Current Zoology 2010年第3期56卷 343-357页

作者： Michael j.RYAN Ximena E.BERNAL A.stanley RAND Section of Integrative Biology C0930 University of Texas Smithsonian Tropical Research Institution Department of Biological Science Texas Tech University Srnithsonian Tropical Research Institution

The potential for ornament evolution in response to sexual selection rests on the interaction between the permissive- ness or selectivity of female preferences and the constraints on male development of signaling related traits. We investigate the former by determining how latent female preferences either exaggerate the magnitude of current traits （i.e. elaborations） or favor novel traits （i.e. innovations）. In tt^ngara frogs, females prefer complex mating calls （whine-chucks） to simple calls （whine only）. The whine is critical for mate recognition while the chuck further enhances the attractiveness of the call. Here we use a combina- tion of synthetic and natural stimuli to examine latent female preferences. Our results show that a diversity of stimuli, including conspecific and heterospecific calls as well as predator-produced and human-made sounds, increase the attractiveness of a call when added to a whine. These stimuli do not make simple calls more attractive than a whine-chuck, however. In rare cases we found stimuli that added to the whine decrease the attractiveness of the call. Overall, females show strong preferences for both elaborations and innovations of the chuck. We argue that the emancipation of these acoustic adornments from mate recognition allows such female permissiveness, and that male constraints on signal evolution are probably more important in explaining why males evolved their specific adornment. Experimentally probing latent female preferences for stimuli out of the species＇ range is a useful means to gain insights about the potential of female choice to influence signal evolution and thus the astounding diversity in male sexually-selected traits [Current Zoology 56 （3）： 343-357, 2010].

关键词： Mate choice Ornament evolution Tfingara frogs Physalaemus pustulosus

A review of methane leakage from abandoned oil and gas wells:A case study in Lubbock,Texas,within the Permian Basin

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Energy Geoscience 2024年第3期5卷 1-12页

作者： stanley U.Opara Chinedu j.Okere Bob L.Herd Department of Petroleum Engineering Texas Tech UniversityTXUSA

In the pursuit of global net zero carbon emissions and climate change mitigation,ongoing research into sustainable energy sources and emission control is *** review examines methane leakage from abandoned oil and gas(AOG)wells,focusing particularly on Lubbock,a geographic area situated within the larger region known as the Permian Basin in West Texas,United *** obj.ctive is to assess the extent and environmental implications of methane leakage from these *** analysis integrates pertinent literature,governmental and industry data,and prior Lubbock *** affecting methane leakage,including well integrity,geological characteristics,and human activities,are *** research estimates 1781 drilled wells in Lubbock,forming a foundation for targeted assessments and monitoring due to historical drilling *** hierarchy of well statuses in Lubbock highlights the prevalence of“active oil wells,”trailed by“plugged and abandoned oil wells”and“inactive oil wells.”Methane leakage potential aligns with these well types,underscoring the importance of strategic monitoring and *** analysis notes a zenith in“drilled and completed”wells during *** our study's case analysis and literature review reiterate the critical significance of assessing and mitigating methane emissions from AOG wells,it's important to clarify that the research does not directly provide methane leakage ***,it contextualizes the issue's magnitude and emphasizes the well type and status analysis's role in targeted mitigation *** summary,our research deepens our understanding of methane leakage,aiding informed decision-making and policy formulation for environmental *** clarifying well type implications and historical drilling patterns,we aim to contribute to effective strategies in mitigating methane emissions from AOG wells.

关键词： Net zero carbon emissions Climate change mitigation Methane emission control Abandoned oil and gas(AOG)well Permian Basin