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降噪大作战

环球科学 2024年第6期 50-51页

作者：斯科特·达特菲尔德不详

我们的家已经变成了噪声的温床——无论是从外界入侵的交通噪声,还是电视和智能手机所制造的噜杂声响,都在这里汇聚交织。声音在空气中传播的基础原理其实非常简单:当物体振动时,它会引起周围空气分子运动并相互碰撞,这种像多米诺骨牌... 详细信息

我们的家已经变成了噪声的温床——无论是从外界入侵的交通噪声,还是电视和智能手机所制造的噜杂声响,都在这里汇聚交织。声音在空气中传播的基础原理其实非常简单:当物体振动时,它会引起周围空气分子运动并相互碰撞,这种像多米诺骨牌一样的连锁反应最终形成了所谓的声波。

关键词：基础原理分子运动智能手机连锁反应多米诺骨牌周围空气交通噪声

Annual-perennial plant relationships and species selection for desert restoration

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Journal of Arid Land 2013年第3期5卷 298-309页

作者： scott R ABELLA Stanley D SMITH Department of Environmental and Occupational Health University of Nevada Las VegasLas VegasNevada 89154-3064USA School of Life Sciences University of Nevada Las VegasLas VegasNevada 89154-4004USA

Exotic plant invasion is a growing concern in the conservation and management of indigenous arid land ecosystems. By creating areas of ameliorated microclimates and fertile soil below their canopies, perennial plants might influence exotic annual plant invasions. We conducted a quantitative literature review of studies that compared exotic annual plant abundance among native perennial plant species and interspace （open areas） microsites in North America＇s Mojave Desert, where exotic plant invasion has corresponded with increasing extent of wildfire and broad-scale ecosystem transformation. Ten studies compared exotic annual plant abundance between inter- spaces and below a total of 36 native perennial species. These studies revealed that：（1） With few exceptions, most native perennial species supported a greater abundance of exotic annuals than interspaces, indicating overall facilitation of exotic species by native perennials. （2） Exotic species abundance varied by orders of magnitude among native perennial species, with some perennial species harboring amounts of exotics similar to interspaces. （3） Distributions of dominant exotic species varied, where Bromus rubens displayed a greater affinity for below-perennial microsites than did Schismus spp. and Erodium cicutarium that often were most abundant in interspaces. Results suggest that the degree of facilitation of exotic plants warrants consideration when selecting native perennial species for revegetation and restoration projects.

关键词： Bromus rubens exotic fertile island invasive nurse plant positive plant interaction Schismus

Glutamine-released ammonia acts as an unprecedented signaling molecule activating lipid production

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Genes & Diseases 2023年第2期10卷 307-309页

作者： Chunming Cheng scott Kelsey Deliang Guo Department of Radiation Oncology Ohio State Comprehensive Cancer CenterArthur G. James Cancer Hospital and Richard J. Solove Research Instituteand College of Medicine at The Ohio State UniversityColumbusOH 43210USA Center for Cancer Metabolism James Comprehensive Cancer Center at The Ohio State UniversityColumbusOH 43210USA

In healthy humans, ammonia circulates in the bloodstream at a concentration around 11–32 μmol/L. Whether ammonia plays any physiological role has been unknown until a recent report published in Nature Metabolism.1 Ammonia, long thought to be a toxic waste product of amino acid metabolism, needs to be excreted from the human body as urea. Intriguingly, in this paper, Cheng et al1 for the first time reported that ammonia is not a waste product;rather, it is an unprecedented signaling molecule tying glucose and glutamine to lipid production in human cells. This study revealed that ammonia released from glutamine triggers a cascade of cellular processes leading to the activation of lipogenesis machinery for lipid production (Fig. 1). This discovery has major implications for developing treatments for human diseases such as cancers and metabolic syndromes, as dysregulated metabolism is a hallmark of these diseases.

关键词： ammonia metabolism Ammonia

Constitutive behavior and processing maps of a new wrought magnesium alloy ZE20 (Mg-2Zn-0.2Ce)

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Journal of Magnesium and Alloys 2020年第1期8卷 111-126页

作者： scott C.Sutton Alan A.Luo Department of Materials Science and Engineering The Ohio State UniversityColumbusOH 43210United States Department of Integrated Systems Engineering The Ohio State UniversityColumbusOH 43210United States Mag Specialties Inc. DenverCO 80210USA

ZE20(Mg-2Zn-0.2Ce)^2 is a new wrought magnesium alloy with improved extrudability and mechanical properties[1].To understand the constitutive behavior and workability of this new alloy,Gleeble thermomechanical testing has been carried out in this *** flow stress behavior of ZE20 was investigated between 250℃–450℃ and 10^–3 s^–1–1.0 s^–1 in isothermal *** descriptions of the flow stress are provided.A new general approach at application of the extended Ludwik equation is demonstrated and was found to be more accurate than the hyperbolic sine Arrhenius model while having a similar number of model *** maps were developed based on the experimental results and are verified with microstructural investigation.A region of safe processing with non-basal texture and high activity of dynamic recrystallization(DRX)was found between 375℃ and 450℃,from 10^–1 s^–1 to 10^–2.5 s^–1.A region of potentially safe processing with annealing that is associated with shear band nucleation of non-basal grains was identified for temperatures as low as 300℃ and rates as high as 10^–1 s^–1.

关键词： Magnesium alloys Thermomechanical processing Constitutive behavior Processing map Deformation mechanisms

Noise-enhanced dynamic single leg balance in subjects with functional ankle instability

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Journal of Sport and Health Science 2012年第2期1卷 102-106页

作者： scott Ross Brent Arnold Virginia Commonwealth University

Background:Stochastic resonance stimulation(SRS) transmits subsensory electrical Gaussian white noise into the body to enhance sensorimotor *** therapy has improved static single leg balance in subjects with functional ankle ***,the effect of this stimulation on dynamic single leg balance is not *** in dynamic single leg balance with SRS may have implications For enhancing functional rehabilitation for ankle ***,the purpose of this study was to determine the effects of SRS on dynamic single leg balance in subjects with functional ankle instability. Methods:This study was an experimental research design and data were collected in a sports medicine research *** subjects with functional ankle instability(69±15 kg;173±10 cm;21±2 years) reported a history of ankle sprains and instability at the ankle with physical activity.A single leg jump-landing test was used to assess dynamic *** were required to jump between 50% and 55% of the maximal vertical jump height,land on a single leg atop a force plate,and stabilize as quickly as ***-landing tests were performed with and without *** trials were performed for each treatment condition(SRS and control).A randomized block design was used to determine test ***/posterior and medial/lateral time-to-stabilization were computed to assess dynamic *** time indicated better ***-tailed paired samples t tests were used for analysis(α≤0.05). Results:SRS improved anterior/posterior time-to-stabilization(stochastic resonance = 1.32±0.31 s,control = 1.74±0.80 s,p = 0.03),but did not enhance medial/lateral time-to-stabilization(stochastic resonance = 1.95±0.40 s,control = 1.92±0.48 s,p = 0.07). Conclusion:Clinicians might use SRS to facilitate balance improvements with sagittal plane dynamic single leg balance exercises that patients may not be able to perform otherwise.

关键词： Chronic Posture Sprain Stochastic resonance

Patent foramen ovale and cryptogenic stroke:diagnosis and updates in secondary stroke prevention

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Stroke & Vascular Neurology 2018年第2期3卷 84-91页

作者： Kristy Yuan scott Eric Kasner Department of Neurology University of PennsylvaniaPhiladelphiaPennsylvaniaUSA

The patent foramen ovale(PFO),given its high prevalence in the general population and especially in patients with cryptogenic stroke,has long generated investigation and debate on its propensity for stroke by paradoxical embolism and its management for stroke *** pendulum has swung for percutaneous PFO closure for secondary stroke prevention in cryptogenic *** on a review of current evidence,the benefit from PFO closure relies on careful patient selection:those under the age of 60 years with few to no vascular risk factors and embolic-appearing stroke deemed cryptogenic after thorough *** these data look towards influencing guideline statements and device approvals in the future,patient selection remains the crucial ingredient for clinical decision making and future trials.

关键词： prevention diagnosis closure

Pharmaceutical salts: Theory, use in solid dosage forms and in situ preparation in an aerosol

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Asian Journal of Pharmaceutical Sciences 2016年第6期11卷 722-734页

作者： Timothy scott Wiedmanna Amir Naqwib Department of Pharmaceutics University of Minnesota308 Harvard St SEMinneapolisMN 55455USA MSP Corporation ShoreviewMN 55126USA

In this article, the theoretical foundation for salts is given with an emphasis on the amount of drug in solution. Consideration is given for the solubility of the non-ionized form, acid dissociation constant and solubility product, which are the limiting constraints. For dissolution of nonionized drugs, the surface pH differs from the bulk pH, giving rise to a lower than expected rate. For salts, theoretical considerations are relatively complex, and an experimental approach to estimating the surface pH is more likely to be of value in predicting the dissolution rate. General guidelines are described for screening, preparing and characterizing drugs as salts, which critically depend on the goal of the product ***, our work involving the preparation of salts as a means to generate aerosols from a solution is provided. The solubility of six structurally related compounds was determined in four acids. Thereafter, the amount of the compound in solution was determined as a function of pH, using the acid that provided the highest solubility. Because the pH required to achieve the needed concentration for aerosol generation was low, ammonia vapor was introduced into the air stream to neutralize aerosol droplets. Solvent was then removed from the aerosol by a silica column. The resulting aerosol had a concentration of 96 μg/l and a mass median particle size of 1.8 μm. The reported pharmacokinetic study substantiated the feasibility of evaluating its safety and efficacy of inhalation administration in the rat model.

关键词： Solubility Salt Aerosol Inhalation Solubility product

Perspectives:Gene expression in fisheries management

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Current Zoology 2010年第1期56卷 157-174页

作者： Jennifer L.NIELSEN scott A.PAVEY US Geological Survey Alaska Science Center Department of Biological Sciences Simon Frasier University National Park Service

Functional genes and gene expression have been connected to physiological traits linked to effective production and broodstock selection in aquaculture, selective implications of commercial fish harvest, and adaptive changes reflected in non-commercial fish populations subject to human disturbance and climate change. Gene mapping using single nucleotide polymorphisms （SNPs） to identify functional genes, gene expression （analogue microarrays and real-time PCR）, and digital sequencing technologies looking at RNA transcripts present new concepts and opportunities in support of effective and sustainable fisheries. Genomic tools have been rapidly growing in aquaculture research addressing aspects of fish health, toxicology, and early development. Genomic technologies linking effects in functional genes involved in growth, maturation and life history development have been tied to selection resulting from harvest practices. Incorporating new and ever-increasing knowledge of fish gehomes is opening a different perspective on local adaptation that will prove invaluable in wild fish conservation and management. Conservation of fish stocks is rapidly incorporating research on critical adaptive responses directed at the effects of human dis- turbance and climate change through gene expression studies. Genomic studies of fish populations can be generally grouped into three broad categories： l） evolutionary genomics and biodiversity; 2） adaptive physiological responses to a changing environment; and 3） adaptive behavioral genomics and life history diversity. We review current genomic research in fisheries focusing on those that use microarrays to explore differences in gene expression among phenotypes and within or across populations, information that is critically important to the conservation of fish and their relationship to humans [Current Zoology 56 （1）： 157-174, 2010].

关键词： Fish genome Fisheries management Conservation Gene expression

A King＇s Two Bodies： The Northern Wei Emperor Wencheng and Representations of the Power of His Monarchy

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Frontiers of History in China 2012年第1期7卷 90-105页

作者： scott Pearce Liberal Studies Department Western Washington University Bellingham WA 98225 USA

This article examines the various ways in which the Northern Wei emperor Wenchengdi （440465; r. 452-465） was portrayed to his subjects. As is the case with many monarchs in many countries, he played different parts before different groups. For his soldiers, he was represented as a great hunter and marksman; to farmers in the lowlands, as a caring protector and benefactor; to potentially rebellious groups on the periphery, as a strong and steady observer of their actions. At the same time, it was in his reign that the Northern Wei court began efforts to use Buddhism as an overarching way to justify rule to all within the realm, by initiating construction of the famous cave-temples at Yungang, where ＂Buddhas became emperors and emperors Buddhas.＂ The spectacles through which Wenchengdi was portrayed are contextualized by a parallel examination of the very difficult life of the person behind the pomp and circumstance.

关键词： Northern Wei Wenchengdi legitimation propaganda ErnstKantorowicz Buddhism military culture