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Microbial community coalescence and nitrogen cycling in simulated mortality decomposition hotspots

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Ecological Processes 2023年第1期12卷 608-624页

作者： Sarah W.Keenan Alexandra L.emmons Jennifer M.DeBruyn Department of Geology and Geological Engineering South Dakota School of Mines and Technology501 East St.Joseph StreetRapidSD 57701USA Department of Anthropology University of TennesseeKnoxvilleTNUSA Department of Biosystems Engineering and Soil Science University of Tennessee2506 E.J.Chapman DriveKnoxvilleTN 37996USA

Background The pulsed introduction of dead plant and animal material into soils represents one of the primary mechanisms for returning organic carbon(C)and nitrogen(N)compounds to biogeochemical *** of animal carcasses provides a high C and N resource that stimulates indigenous environmental microbial communities and introduces non-indigenous,carcass-derived microbes to the ***,the dynamics of the coalesced microbial communities,and the relative contributions of environment-and carcass-derived microbes to C and N cycling are *** test whether environment-derived,carcass-derived,or the combined microbial communities exhibited a greater influence on C and N cycling,we conducted controlled laboratory experiments that combined carcass decomposition fluids and soils to simulate carcass decomposition *** selectively sterilized the decomposition fluid and/or soil to remove microbial communities and create different combinations of environment-and carcass-derived communities and incubated the treatments under three temperatures(10,20,and 30℃).Results Carcass-derived bacteria persisted in soils in our simulated decomposition scenarios,albeit at low *** communities had higher respiration rates at 10 and 30℃ compared to soil or carcass communities ***,at higher temperatures,mixed communities had reduced diversity,but higher respiration,suggesting functional *** communities treatments also provided evidence that carcass-associated microbes may be contributing to ammonification and denitrification,but that nitrification is still primarily carried out by native soil *** Our work yields insight into the dynamics of microbial communities that are coalescing during carcass decomposition,and how they contribute to recycling carcasses in terrestrial ecosystems.

关键词： Carcass decomposition Microcosm Nitrogen Carbon Biogeochemical cycling Coalescence

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Mapping super-resolution image quality

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Light(Science & Applications) 2024年第2期13卷 178-180页

作者： megan A.Steves Ke Xu Department of Chemistry University of CaliforniaBerkeleyCA94720USA

The local quality of super-resolution microscopy images can be assessed and mapped by rolling Fourier ring correlation,even when image quality varies within a single image.

关键词： image resolution Mapping

Recent advances and future therapy development for Alzheimer’s disease and related disorders

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Neural Regeneration Research 2024年第9期19卷 1877-1878页

作者： megan Hong Gal Bitan Department of Neurology David Geffen School of MedicineUniversity of California Los AngelesLos AngelesCAUSA Department of Chemistry and Biochemistry University of California Los AngelesLos AngelesCAUSA Molecular Biology Institute University of California Los AngelesLos AngelesCAUSA Brain Research Institute University of CaliforniaLos AngelesCAUSA

Over 55 million people globally live with Alzheimer’s disease(AD)or related dementias(ADRD)and the number is expected to double every twenty *** i l recent l y,onl y symptomatic treatments were available to patients with AD,including acetylcholine esterase inhibitors,of which the last one,galantamine,was approved by the US Food and Drug Administration(FDA)in 2001.

关键词： Alzheimer globally patients

Snapshot of HIV pathogenesis in China

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Cell Research 2005年第Z1期15卷 953-961页

作者： Nitin K SAKSENA megan STEAIN Retroviral Genetics Division Centre for Virus Research Westmead Millennium Institute The University of Sydney Westmead NSW 2145 Sydney Australia

Several reviews have focused on the nature of HIV infection and its spread in various geographical regions of China. In contrast, this review provides a comprehensive update on the prevalence of multiple HIV-1 subtypes, consequent emergence of recombinant and novel forms of HIV-1 in China, and the implications this may have on HIV diversity and the development of effective vaccines. In addition it also examines the dissemination of primary drug resistance in therapy na?ve patients, as well as co-infections with two other important viruses-hepatitis B and C. The main purpose of this review is to provide a current snapshot of HIV-1 pathogenesis in China and possibly shed some light on the future of HIV evolution, and potential challenges for future vaccine and anti-retroviral therapeutics against HIV strains in this area.

关键词： HIV recombination circulating recombinant forms co-infections AIDS.

A Radio-Telemetry System for Navigation and Recording Neuronal Activity in Free-Roaming Rats

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Journal of Bionic Engineering 2012年第4期9卷 402-410页

作者： Dian Zhang Yanling Dong megan Li Houjun Wang School of Automation Engineering University of Electronic Science and Technology of China Chengdu 611731 P. R. China School of Medicine Qingdao University Qingdao 266071 P R. China Shandong Eye Institute Qingdao 266071 P. R. China Zanvyl Krieger School of Arts and Sciences The Johns Hopkins University Baltimore 21218 USA

A radio-telemetry recording system is presented which is applied to stimulate specific brain areas and record neuronal ac- tivity in a free-roaming rat. The system consists of two major parts： stationary section and mobile section. The stationary section contains a laptop, a Micro Control Unit （MCU）, an FM transmitter and a receiver. The mobile section is composed of the headstage and the backpack （which includes the mainboard, FM transmitter, and receiver）, which can generate biphasic mi- crocurrent pulses and simultaneously acquire neuronal activity. Prior to performing experiments, electrodes are implanted in the Ventral Posterolateral （VPL） thalamic nucleus, primary motor area （M1） and Medial Forebrain Bundle （MFB） of the rat. The stationary section modulates commands from the laptop for stimulation and demodulates signals for neuronal activity recording. The backpack is strapped on the back of the rat and executes commands from the stationary section, acquires neuronal activity, and transmits the neuronal activity singles of the waking rat to the stationary section. All components in the proposed system are commercially available and are fabricated from Surface Mount Devices （SMD） in order to reduce the size （25 mm×15 mm ×2 mm） and weight （10 g with battery）. During actual experiments, the backpack, which is powered by a rechargeable Lithium battery （4 g）, can generate biphasic microcurrent pulse stimuli and can also record neuronal activity via the FM link with a maximum transmission rate of 1 kbps for more than one hour within a 200 m range in an open field or in a neighboring chamber. The test results show that the system is able to remotely navigate and control the rat without any prior training, and acquire neuronal activity with desirable features such as small size, low power consumption and high precision when compared with a commercial 4-channel bio-signal acquisition and processing system.

关键词： bio-robot radio-telemetry microcurrent stimulation navigation neuronal activity recording

Polarity, Continuity, and Alignment in Plant Vascular Strands

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Journal of Integrative Plant Biology 2013年第9期55卷 824-834页

作者： megan G.Sawchuk Enrico Scarpella Department of Biological Sciences University of AlbertaEdmonton Alberta Canada T6G 2E9

Plant vascular cells are joined end to end along uninterrupted lines to connect shoot organs with roots;vascular strands are thus polar, continuous, and internally aligned. What controls the formation of vascular strands with these properties？ The “auxin canalization hypothesis”-based on positive feedback between auxin flow through a cell and the cell’s capacity for auxin transport-predicts the selection of continuous files of cells that transport auxin polarly, thus accounting for the polarity and continuity of vascular strands. By contrast, polar, continuous auxin transport-though required-is insufficient to promote internal alignment of vascular strands, implicating additional factors. The auxin canalization hypothesis was derived from the response of mature tissue to auxin application but is consistent with molecular and cellular events in embryo axis formation and shoot organ development. Objections to the hypothesis have been raised based on vascular organizations in callus tissue and shoot organs but seem unsupported by available evidence. Other objections call instead for further research; yet the inductive and orienting influence of auxin on continuous vascular differentiation remains unique.

关键词： Auxin transport callus tissue embryo axis leaf vein vascular network.

A data-driven approach to modeling high-density terminal areas：A scenario analysis of the new Beijing,China airspace

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Chinese Journal of Aeronautics 2017年第2期30卷 538-553页

作者： Max Z.Li megan S.Ryerson Department of Electrical and Systems Engineering University of Pennsylvania Philadelphia PA 19104 USA Department of City and Regional Planning University of Pennsylvania Philadelphia PA 19104 USA

Airports are being developed and expanded rapidly in China to accommodate and promote a growing aviation *** future Beijing Daxing International Airport（DAX） will serve as the central airport of the JingJinJi megaregion,knitting the Beijing,Tianjin,and Hebei regions *** will be a busy airport from its inception,relieving congestion and accommodating growth from Beijing Capital International Airport（PEK）,currently the second busiest airport in the world in passengers *** aim to model terminal airspace designs and possible conflicts in the future Beijing Multi-Airport System（MAS）.We investigate standard arrival procedures and mathematically model current and future arrival trajectories into PEK and DAX by collecting large quantities of publicly available track data from historical arrivals operating within the Beijing terminal *** find that（1） trajectory models constructed from real data capture aberrations and deviations from standard arrival procedures,validating the need to incorporate data on historical trajectories with standard procedures when evaluating the airspace and（2） given all existing constraints,DAX may be restricted to using north and east arrival flows,constraining the capacity required to handle the increases in air traffic demand to *** results indicate that the terminal airspace above Beijing,and the future JingJinJi region,requires careful consideration if the full capacity benefits of the two major airports are to be realized.

关键词： Air traffic management Beijing airspace Multi-airport system Trajectory modeling Terminal airspace

An investigation of the effects of hydrochar application rate on soil amelioration and plant growth in three diverse soils

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Biochar 2021年第3期3卷 349-365页

作者： megan de Jager Luise Giani Carl Von Ossietzky Universität Institut Für Biologie Und UmweltwissenschaftenOldenburgGermany

The hydrothermal carbonization(HTC)of biogas digestate alters the raw materials inherent characteristics to produce a carbon(C)-rich hydrochar(HC),with an improved suitability for soil *** studies report conflicting impacts of various HC application rates on soil properties and plant *** this study,the influence of HC application rate on soil improvement and plant growth aspects was investigated in three diverse soils(Chernozem,Podzol,and Gleysol).Pot trials were conducted in which all soils were amended with 5,10,20 and 30%(w/w)HC in quintuplicate,with two controls of pure soil(with and without plants,respectively)also *** to potting,soil samples were collected from all HC-amended soils and controls and analyzed for soil pH,plant available nutrients(PO4-P and K),and microbial activity using standard laboratory and statistical *** after potting,a 6-week seed germination experiment using Chinese cabbage was conducted to determine germination success,followed by a plant growth experiment of equal duration and plant species to determine biomass *** the end of the study(after a total plant growth period of 12 weeks),each pot was sampled and comparatively analyzed for the same soil properties as at the beginning of the *** pH shifted toward the pH of the HC(6.6)in all soils over the course of the study,but was most expressed in the 20%and 30%application rates,confirming the well-documented liming effect of *** addition of HC increased the PO4-P and K contents,particularly with 20%and 30%HC *** results are proposedly due to the large labile C fraction of the HC,which is easily degradable by *** rapid decomposition of this C fraction prompted the quick release of the HCs inherently high PO4-P and K content into the soil,and in turn,further stimulated microbial activity,until this fraction was essentially *** addition did not inhibit seed germination at any rate,presumabl

关键词： Biogas digestate Hydrochar application rate Soil improvement Nutrient availability Microbial activity

Heidegger on the Struggle for Belongingness and Being at Home

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Frontiers of Philosophy in China 2016年第3期11卷 444-462页

作者： megan Altman Department of Philosophy Hiram College Hiram OH 44234 USA

In 1840, Alexis de Tocqueville coined the term ＂individualism＂ to refer to the tendency for Americans to withdraw into their own desires and interests, thus weakening and diminishing the ＂habits of the heart＂ that bind a generation to the customs of their forebears and contemporaries. A problem, though, is that modem individualism undermines the very ideals--i.e, autonomy, equality, and freedom--that motivated it in the first place. Understood as a way of life, liberal individualism is permeated by alienation, estrangement, and thoughtless patterns of conformism. In what follows, I hope to show that hermeneutic phenomenology as developed by Martin Heidegger marks an important break from the modem liberal individualistic outlook. The point is to undercut the contrived interpretations of our current historical tradition in order to demonstrate that belonging to and sharing in the struggles of a generation are conditions for being human at all. This critique does not provide a panoptic or definitive account of the basis of a genuine community, but does give us a richer sense of place and purpose, beyond even what the current polis/political community designates （though it certainly includes it）.

关键词： Martin Heidegger ontological individualism hermeneutic phenomenology Ethos