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Transient thermal response of micro-thermal conductivity detector (μTCD) for the identification of gas mixtures:An ultra-fast and low power method

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Microsystems & Nanoengineering 2015年第1期1卷 52-58页

作者： Alireza Mahdavifar Milad Navaei Peter j.hesketh Melvin Findlay joseph R.Stetter Gary W.Hunter School of Mechanical Engineering Georgia Institute of TechnologyAtlantaGA 30332USA KWj Engineering Inc. NewarkCA 94560USA NASA Glenn Research Center ClevelandOH 44135USA

Micro-thermal conductivity detector(μTCD)gas sensors work by detecting changes in the thermal conductivity of the surrounding medium and are used as detectors in many applications such as gas chromatography *** TCDs use steady-state resistance(i.e.,temperature)measurements of a *** this work,we developed a new measurement method and hardware configuration based on the processing of the transient response of a low thermal mass TCD to an electric current *** method was implemented for a 100-μm-long and 1-μm-thick micro-fabricated bridge that consisted of doped polysilicon conductive film passivated with a 200-nm silicon nitride *** resistance variations of theμTCD in response to a square current pulse were studied in multiple mixtures of dilute gases in *** and experimental results are presented and compared for the time resolved and steady-state regime of the sensor *** analysis and simulation show that the sensor response is exponential in the transient state,that the time constant of this exponential variation was a linear function of the thermal conductivity of the gas ambient,and that the sensor was able to quantify the mixture *** level of detection in nitrogen was estimated to be from 25 ppm for helium to 178 ppm for carbon *** this novel approach,the sensor requires approximately 3.6 nj for a single measurement and needs only 300μs of sampling *** is less than the energy and time required for steady-state DC measurements.

关键词： gas sensor MEMS micro-bridge micro-heater μTCD thermal conductivity sensor transient heat transfer modeling

Microfluidic pumping using artificial magnetic cilia

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Microsystems & Nanoengineering 2018年第1期4卷 300-308页

作者： Srinivas Hanasoge Peter j.hesketh Alexander Alexeev George W.Woodruff School of Mechanical Engineering Georgia Institute of TechnologyAtlantaGA 30332USA

One of the vital functions of naturally occurring cilia is fluid *** cilia use spatially asymmetric strokes to generate a net fluid flow that can be utilized for feeding,swimming,and other *** synthetic cilia with similar asymmetric beating can be useful for fluid manipulations in lab-on-chip *** this paper,we demonstrate the microfluidic pumping by magnetically actuated synthetic cilia arranged in multi-row *** use a microchannel loop to visualize flow created by the ciliary array and to examine pumping for a range of cilia and microchannel *** show that magnetic cilia can achieve flow rates of up to 11μl/min with the pressure drop of~1 *** magnetic ciliary array can be useful in microfluidic applications requiring rapid and controlled fluid transport.

关键词： pumping fluid magnetic

The impact of macroalgae on mean and turbulent flow fields

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journal of Hydrodynamics 2015年第3期27卷 427-435页

作者： THOMAS Robert E. MCLELLAND stuart j. Department of Geography Environment and Earth Sciences University of Hull

In this paper, we attempt to quantify the mean and turbulent flow fields around live macroalgae within a tidal inlet in Norway. Two Laminaria digitata specimens - 0.50 m apart were selected for detailed study and a profiling ADV was used to collect 45 velocity profiles, each composed of up to seven 0.035 m-high profiles collected for 240 s at 100 Hz, at a streamwise spacing of 0.25 m and cross-stream spacing of 0.20 m. To quantify the impact of the macroalgae, measurements were repeated over a sparser grid after the region had been completely cleared of algae and major roughness elements.

关键词： dealiasing laminaria digitata turbulence vectrino profiler velocity profile

The effects of gonadal hormones on learning and memory in male mammals： A review

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Current Zoology 2011年第4期57卷 543-558页

作者： stuart T. LEONARD Peter j. WINSAUER Department of Pharmacology and Experimental Therapeutics Louisiana State University Health Sciences Center 1901 Perdido Street New Orleans LA 70112-1393

The primary role of the gonadal steroid hormones in mammals is to regulate reproduction and related behaviors; however, both androgens and estrogens are also integrally involved in mediating higher brain function and processes including cognition, neural development, and neural plasticity. In particular, a number of studies show that estradiol modulates dendritic spine growth and synapse density （synaptic plasticity） in the hippocampus of females, and that increased estradiol levels are generally associated with improvements on a variety of learning and memory tasks. While the majority of research has focused on the beneficial effects of estradiol in females, much less attention has been given to testosterone and its effects on learning and memory in males. Similar to estradiol titers in females, testosterone titers in males decline with age, albeit more gradually, and this decline has been correlated with impairment of certain cognitive tasks. Moreover, studies involving both humans and animals indicate that testosterone and its metabolites can augment responding on certain behavioral tasks, depending on the subject＇s current hormonal state, the response required, and the stimuli involved （e.g., those involving spatial or nonspatial stimuli）. While the exact mechanisms by which testosterone exerts its effects on learning and memory are not fully understood, recent findings suggest that testosterone modulates learning and memory in males through an interaction with the cholinergic system. The overall objective of this review is to discuss studies investigating the role of the gonadal hormones in mediating learning and memory processes in male mammals [Current Zoology 57 （4）： 543-558, 2011].

关键词： Testosterone Learning and memory Cholinergic system Mammals Cognition Androgens

Neurodevelopmental defects as a primer of neurodegeneration:lessons from spinal muscular atrophy and Huntington's disease

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Neural Regeneration Research 2023年第9期18卷 1952-1953页

作者： stuart j.Grice ji-Long Liu Medical Research Council Functional Genomics Unit Department of PhysiologyAnatomy and GeneticsUniversity of OxfordOxfordUK School of Life Science and Technology ShanghaiTech UniversityShanghaiChina

Developmental motifs in neurodegeneration:Neurodegeneration,the prominent feature of neurodegenerative disease,is characterized by the progressive and selective loss of neuronal *** some of the pathologies caused by neurodegeneration may be irreversible,early intervention will be required for the treatments that aim to slow or halt the manifestation of these ***,neurodegeneration evokes the idea of a progressive decline of brain function.

关键词： neurodegeneration Huntington function

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

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World journal 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 july 2007 and july 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

Vocal repertoire of the New Zealand kea parrot Nestor notabilis

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Current Zoology 2012年第5期58卷 727-740页

作者： Raoul SCHWING stuart PARSONS Ximena j. NELSON School of Biological Sciences University of Auckland Private Bag 92019 Auckland New Zealand School of Biological Sciences University of Canterbury Private Bag 4800 Christchurch New Zealand

The unique alpine-living kea parrot Nestor notabilis has been the focus of numerous cognitive studies, but its com- munication system has so far been largely neglected. We examined 2,884 calls recorded in New Zealand＇s Southern Alps. Based on audio and visual spectrographic differences, these calls were categorised into seven distinct call types： the non-oscillating ＇screech＇ contact call and ＇mew＇; and the oscillating ＇trill＇, ＇chatter＇, ＇warble＇ and ＇whistle＇; and a hybrid ＇screech-trill＇. Most of these calls contained aspects that were individually unique, in addition to potentially encoding for an individual＇s sex and age. Additionally, for each recording, the sender＇s previous and next calls were noted, as well as any response given by conspecifics. We found that the previous and next calls made by the sender were most often of the same type, and that the next most likely pre- ceding and/or following call type was the screech call, a contact call which sounds like the ＇kee-ah＇ from which the bird＇s name derives. As a social bird capable of covering large distances over visually obstructive terrain, long distance contact calls may be of considerable importance for social cohesion. Contact calls allow kea to locate conspecifics and congregate in temporary groups for social activities. The most likely response to any given call was a screech, usually followed by the same type of call as the ini- tial call made by the sender, although responses differed depending on the age of the caller. The exception was the warble, the kea＇s play call, to which the most likely response was another warble. Being the most common call type, as well as the default response to another call, it appears that the ＇contagious＇ screech contact call plays a central role in kea vocal communication and social cohesion [Current Zoology 58 （5）： 727-740, 2012].

关键词： Acoustic signals Communication Kea Psittacidae Social behaviour Habitat

Case-control study of factors that trigger inflammatory bowel disease flares

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World journal of Gastroenterology 2014年第15期20卷 4329-4334页

作者： Linda A Feagins Ramiz Iqbal stuart j Spechler VA North Texas Healthcare System DallasTX 75216United States Division of Gastroenterology University of Texas Southwestern Medical CenterDallasTX 75216United States

AIM: To explore the association between inflammatory bowel diseases (IBD) flares and potential triggers.

关键词： Inflammatory bowel diseases, Flare, Non-adherence, Crohn’ s disease, Ulcerative colitis

Reservoir quality of fluvial sandstone reservoirs in salt-walled mini- basins： an example from the Seagull field, Central Graben, North Sea, UK

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Petroleum Science 2018年第1期15卷 1-27页

作者： Stephan Stricker stuart j.jones Neil Meadows Leon Bowen Department of Earth Sciences Durham University South Road Durham DH1 3LE UK RedRock Associates International Limited 38 Queens DrivePrenton Wirral CH43 0RP UK Department of Physics Durham University South RoadDurham DH1 3LE UK

The Triassic fluvial sandstones of the Skagerrak Formation were deposited in a series of salt-walled mini-basins and act as important hydrocarbon reservoirs for several high-pressure, high-temperature（HPHT） fields in the Central Graben, North Sea. The HPHT reservoirs exhibit excellent reservoir quality considering their depth of burial and hence have been of high interest for hydrocarbon exploration. This research uses a multidisciplinary approach to assess the Skagerrak Formation fluvial reservoir quality from the Seagull field incorporating core analysis, petrography, electron microscopy, XRD analysis, fluid inclusion appraisal and burial history modelling. Halokinesis and salt withdrawal at the margin of the saltwalled mini-basin induced early disaggregation bands and fractures at shallow burial and led to increased influx of meteoric water and clay mineral infiltration from overlying sedimentation. The density of disaggregation bands correlates with the occurrence and magnitude of pore-filling authigenic clay minerals, concentrated along the margin of the saltwalled mini-basin. The fluvial channel sandstones of the Skagerrak Formation are subject to strong intra-basinal spatial reservoir quality variations despite diagenesis and low vertical effective stress having played a favourable role in arresting porosity loss.

关键词： Reservoir quality Halokinesis - Diagenesis Clay minerals Porosity Disaggregation bands Salt-walled mini-basin