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Indoor environmental quality of classrooms in Southern European climate

Almeida, Ricardo; Freitas, Vasco
Fonte: Instituto Politécnico de Viseu Publicador: Instituto Politécnico de Viseu
Tipo: Artigo de Revista Científica
Publicado em /10/2014 Português
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The indoor environmental quality within a classroom is linked to the health, comfort and performanceof students. It is well established that there are classroom environments where indoor environmentalquality is poor. Therefore, the rehabilitation of school buildings is assumed as an appropriate strategy.Consequently, some countries have sponsored nationwide programs for the rehabilitation of school build-ings, whose result has been, in some cases, other than the expected. Classrooms performance in serviceconditions must be evaluated and, from the results, optimized solutions should be established and care-fully designed and executed to have the desired effect. Thus, a research project was defined, aiming toassess the impact of retrofit on the indoor environmental quality of school buildings. The methodologyused included the in situ measurement of temperature, relative humidity, carbon dioxide concentrationand ventilation rates. A total of 24 classrooms of 9 school buildings (2 non-retrofitted and 7 recentlyretrofitted) were studied. A long term monitoring was defined with three measurement campaigns:winter, mid-season and summer conditions, each with three weeks length. The results confirmed thatnon-retrofitted schools need to improve their indoor environmental conditions and in retrofitted build-ings mechanical ventilation systems are not being used...

Diurnal Variation in Situ of Photosynthetic Capacity in Ulva Is Caused by a Dark Reaction 1

Mishkind, Michael; Mauzerall, David; Beale, Samuel I.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /11/1979 Português
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Ulva lactuca (sea lettuce) undergoes large diurnal oscillations of light-saturated photosynthetic O2 evolution in situ. Freshly collected samples from Great Harbor, Woods Hole, Massachusetts, had a maximum white light-saturated rate at noon that was 2.5-fold higher than the rate of matched samples collected at midnight. When kept under constant low level illumination, the cycle persisted for at least 36 hours, and after 2 weeks damped out to a constant level that was halfway between the minimum and maximum rates. The cyclic oscillations were apparent whether expressed on a weight or chlorophyll content basis, occurred in both lightly and heavily pigmented samples, and were not attributable to changes in chloroplast shading due to variations in chloroplast orientation within the frond cells. There were no cyclic variations in the initial slopes of the light saturation curves, in photosynthetic unit size, or in relative quantum efficiency. Measurement of the “fast” turnover time of photosynthesis by the delayed dual flash technique revealed no diurnal variations of this parameter. These results indicate that the cyclic variations in photosynthetic activity are modulated by a dark reaction at a step occurring after reduction of plastoquinone by electrons from photosystem II.

Measurement of protein synthesis in rat lungs perfused in situ

Watkins, Clyde A.; Rannels, D. Eugene
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em 15/04/1980 Português
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Compartmentalization of amino acid was investigated to define conditions required for accurate measurements of rates of protein synthesis in rat lungs perfused in situ. Lungs were perfused with Krebs–Henseleit bicarbonate buffer containing 4.5% (w/v) bovine serum albumin, 5.6mm-glucose, normal plasma concentrations of 19 amino acids, and 8.6–690μm-[U-14C]phenylalanine. The perfusate was equilibrated with the same humidified gas mixture used to ventilate the lungs [O2/CO2 (19:1) or O2/N2/CO2 (4:15:1)]. [U-14C]Phenylalanine was shown to be a suitable precursor for studies of protein synthesis in perfused lungs: it entered the tissue rapidly (t½, 81s) and was not converted to other compounds. As perfusate phenylalanine was decreased below 5 times the normal plasma concentration, the specific radioactivity of the pool of phenylalanine serving as precursor for protein synthesis, and thus [14C]phenylalanine incorporation into protein, declined. In contrast, incorporation of [14C]histidine into lung protein was unaffected. At low perfusate phenylalanine concentrations, rates of protein synthesis that were based on the specific radioactivity of phenylalanyl-tRNA were between rates calculated from the specific radioactivity of phenylalanine in the extracellular or intracellular pools. Rates based on the specific radioactivities of these three pools of phenylalanine were the same when extracellular phenylalanine was increased. These observations suggested that: (1) phenylalanine was compartmentalized in lung tissue; (2) neither the extracellular nor the total intracellular pool of phenylalanine served as the sole source of precursor for protein; (3) at low extracellular phenylalanine concentrations...

Simultaneous measurement of gastric acid and duodenal alkali secretion by in situ titration in health and disease.

Dubey, P; Nundy, S
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /12/1983 Português
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We have devised a technique for simultaneously measuring the acid secretion into the stomach and alkali into the duodenum by in situ titration using a modification of the technique of Fordtran and Walsh. Using this technique, the results of acid and alkali secretion measured simultaneously were identical with those obtained using the conventional aspiration method on separate days. In response to stimulation with pentagastrin acid output was 17.2 +/- 1.4 vs 15.4 +/- 1.9 mmol/h and alkali response with secretin was 16.0 +/- 0.8 vs 14.4 +/- 1.5 mmol/h. The response to food was measured in 10 control subjects, 10 patients with duodenal ulcer, and 10 patients with pancreatitis. In controls, the acid and alkaline secretion were similar (15.8 +/- 1.7 vs 18.2 +/- 1.3 mmol/h), in patients with duodenal ulcer acid secretion was significantly greater than alkaline secretion (31.9 +/- 2.2 vs 21.9 +/- 1.7 mmol/h), and in patients with pancreatitis the alkali secretion was significantly less than acid (19.8 +/- 1.9 mmol/h acid vs 11.4 +/- 0.6 mmol/h alkali). It can, therefore, be concluded that in response to food the patients with duodenal ulcer are significant hypersecretors of acid (DU acid greater than DU alkali output) and patients with pancreatitis are significant hyposecretors of alkali (pancreatitis-alkaline output less than acid output) and normal subjects secrete equal amounts of acid and alkali.

In situ measurement of the electrical potential across the phagosomal membrane using FRET and its contribution to the proton-motive force

Steinberg, Benjamin E.; Touret, Nicolas; Vargas-Caballero, Mariana; Grinstein, Sergio
Fonte: National Academy of Sciences Publicador: National Academy of Sciences
Tipo: Artigo de Revista Científica
Português
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Phagosomes employ lytic enzymes, cationic peptides, and reactive oxygen intermediates to eliminate invading microorganisms. The effectiveness of these microbicidal mechanisms is potentiated by the acidic pH created by H+-pumping vacuolar-type ATPases (V-ATPases) on the phagosomal membrane. The degree of phagosomal acidification varies greatly among neutrophils, macrophages, and dendritic cells and can be affected by diseases like cystic fibrosis. The determinants of phagosomal pH are not completely understood, but the permeability to ions that neutralize the electrogenic effect of the V-ATPase has been proposed to play a central role. When counterion conductance is limiting, generation of a large membrane potential will dominate the proton-motive force (pmf), with a proportionally diminished pH gradient. Validation of this notion requires direct measurement of the electrical potential that develops across the phagosomal membrane (ΨΦ). We describe a noninvasive procedure to estimate ΨΦ in intact cells, based on fluorescence resonance energy transfer. This approach, in combination with measurements of phagosomal pH, enabled us to calculate the pmf across phagosomes of murine macrophages and to analyze the factors that limit acidification. At steady state...

In situ assessment of the role of the beta 1-, beta 2- and beta 3-adrenoceptors in the control of lipolysis and nutritive blood flow in human subcutaneous adipose tissue.

Barbe, P.; Millet, L.; Galitzky, J.; Lafontan, M.; Berlan, M.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /03/1996 Português
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1. The involvement of beta 1-, beta 2- and beta 3-adrenoceptors in the control of lipolysis and nutritive blood flow was investigated in abdominal subcutaneous adipose tissue of healthy young adults by use of an in situ microdialysis technique. 2. Dialysis probes were infused either with isoprenaline (non-selective beta-adrenoceptor agonist), CGP 12,177 (selective beta 3-adrenoceptor agonist having beta 1-/beta 2-antagonist properties), dobutamine (selective beta 1-adrenoceptor agonist) or terbutaline (selective beta 2-adrenoceptor agonist). The recovery of each probe used for perfusion was calculated by an in vivo calibration method. The local blood flow was estimated through the measurement of the escape of ethanol infused simultaneously with the drugs included in the probe. 3. Isoprenaline infusion at 0.01 microM had a weak effect while higher concentrations of isoprenaline (0.1 and 1 microM) caused a rapid, sustained and concentration-dependent increase of glycerol outflow; the maximum increase was 306 +/- 34% with 1 microM. Isoprenaline also increased the nutritive blood flow in adipose tissue; a significant effect appeared at 0.1 microM isoprenaline and was greater at 1 microM. 4. CGP 12,177 (10 and 100 microM) increased the glycerol concentration in the dialysate (128 +/- 8 and 149 +/- 12%...

In Situ Activity of Suspended and Immobilized Microbial Communities as Measured by Fluorescence Lifetime Imaging▿

Walczysko, Petr; Kuhlicke, Ute; Knappe, Sabine; Cordes, Christiana; Neu, Thomas R.
Fonte: American Society for Microbiology (ASM) Publicador: American Society for Microbiology (ASM)
Tipo: Artigo de Revista Científica
Português
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In this study, the feasibility of fluorescence lifetime imaging (FLIM) for measurement of RNA:DNA ratios in microorganisms was assessed. The fluorescence lifetime of a nucleic acid-specific probe (SYTO 13) was used to directly measure the RNA:DNA ratio inside living bacterial cells. In vitro, SYTO 13 showed shorter fluorescence lifetimes in DNA solutions than in RNA solutions. Growth experiments with bacterial monocultures were performed in liquid media. The results demonstrated the suitability of SYTO 13 for measuring the growth-phase-dependent RNA:DNA ratio in Escherichia coli cells. The fluorescence lifetime of SYTO 13 reflected the known changes of the RNA:DNA ratio in microbial cells during different growth phases. As a result, the growth rate of E. coli cells strongly correlated with the fluorescence lifetime. Finally, the fluorescence lifetimes of SYTO 13 in slow- and fast-growing biofilms were compared. For this purpose, biofilms developed from activated sludge were grown as autotrophic and heterotrophic communities. The FLIM data clearly showed a longer fluorescence lifetime for the fast-growing heterotrophic biofilms and a shorter fluorescence lifetime for the slow-growing autotrophic biofilms. Furthermore, starved biofilms showed shorter lifetimes than biofilms supplied with glucose...

Quantifying Genes and Transcripts To Assess the In Situ Physiology of “Dehalococcoides” spp. in a Trichloroethene-Contaminated Groundwater Site▿ †

Lee, Patrick K. H.; Macbeth, Tamzen W.; Sorenson, Kent S.; Deeb, Rula A.; Alvarez-Cohen, Lisa
Fonte: American Society for Microbiology (ASM) Publicador: American Society for Microbiology (ASM)
Tipo: Artigo de Revista Científica
Português
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Quantitative PCR (qPCR) was coupled with reverse transcription (RT) to analyze both gene copy numbers and transcripts of the 16S rRNA gene and three reductive dehalogenase (RDase) genes (tceA, vcrA, and bvcA) as biomarkers of “Dehalococcoides” spp. in the groundwater of a trichloroethene-dense nonaqueous-phase liquid site at Fort Lewis, WA, that was sequentially subjected to biostimulation and bioaugmentation. Dehalococcoides cells carrying the tceA, vcrA, and bvcA genes were indigenous to the site. The sum of the three identified RDase gene copy numbers closely correlated to 16S rRNA gene copy numbers throughout the biostimulation and bioaugmentation activity, suggesting that these RDase genes represented the major Dehalococcoides metabolic functions at this site. Biomarker quantification revealed an overall increase of more than 3 orders of magnitude in the total Dehalococcoides population through the 1-year monitoring period (spanning biostimulation and bioaugmentation), and measurement of the respective RDase gene concentrations indicated different growth dynamics among Dehalococcoides cells. The Dehalococcoides cells containing the tceA gene consistently lagged behind other Dehalococcoides cells in population numbers and made up less than 5% of the total Dehalococcoides population...

Functional consequences of the collagen/elastin switch in vascular remodeling in hyperhomocysteinemic wild-type, eNOS−/−, and iNOS−/− mice

Steed, Mesia M.; Tyagi, Neetu; Sen, Utpal; Schuschke, Dale A.; Joshua, Irving G.; Tyagi, Suresh C.
Fonte: American Physiological Society Publicador: American Physiological Society
Tipo: Artigo de Revista Científica
Português
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A decrease in vascular elasticity and an increase in pulse wave velocity in hyperhomocysteinemic (HHcy) cystathionine-β-synthase heterozygote knockout (CBS−/+) mice has been observed. Nitric oxide (NO) is a potential regulator of matrix metalloproteinase (MMP) activity in MMP-NO-tissue inhibitor of metalloproteinase (TIMP) inhibitory tertiary complex. However, the contribution of the nitric oxide synthase (NOS) isoforms eNOS and iNOS in the activation of latent MMP is unclear. We hypothesize that the differential production of NO contributes to oxidative stress and increased oxidative/nitrative activation of MMP, resulting in vascular remodeling in response to HHcy. The overall goal is to elucidate the contribution of the NOS isoforms, endothelial and inducible, in the collagen/elastin switch. Experiments were performed on six groups of animals [wild-type (WT), eNOS−/−, and iNOS−/− with and without homocysteine (Hcy) treatment (0.67 g/l) for 8–12 wk]. In vivo echograph was performed to assess aortic timed flow velocity for indirect compliance measurement. Histological determination of collagen and elastin with trichrome and van Gieson stains, respectively, was performed. In situ measurement of superoxide generation using dihydroethidium was used. Differential expression of eNOS...

Apolipoprotein E: Isoform Specific Differences in Tertiary Structure and Interaction with Amyloid-β in Human Alzheimer Brain

Jones, Phillip B.; Adams, Kenneth W.; Rozkalne, Anete; Spires-Jones, Tara L.; Hshieh, Tammy T.; Hashimoto, Tadafumi; von Armin, Christine A. F.; Mielke, Mathew; Bacskai, Brian J.; Hyman, Bradley T.
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 31/01/2011 Português
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We applied a novel application of FLIM-FRET to in situ measurement and quantification of protein interactions to explore isoform specific differences in Aβ-ApoE interaction and ApoE tertiary conformation in senile plaques in human Alzheimer brain. ApoE3 interacts more closely with Aβ than ApoE4, but a greater proportion of Aβ molecules within plaques are decorated with ApoE4 than ApoE3, lending strong support to the hypothesis that isoform specific differences in ApoE are linked with Aβ deposition. We found an increased number of ApoE N-terminal fragments in ApoE4 plaques, consistent with the observation that ApoE4 is more easily cleaved than ApoE3. In addition, we measured a small but significant isoform specific difference in ApoE domain interaction. Based on our in situ data, supported by traditional biochemical data, we propose a pathway by which isoform specific conformational differences increase the level of cleavage at the hinge region of ApoE4, leading to a loss of ApoE function to mediate clearance of Aβ and thereby increase the risk of AD for carriers of the APOEε4 allele.

Electrochemical Activation of Diamond Microelectrodes: Implications for the In Vitro Measurement of Serotonin in the Bowel

Duran, Boris; Brocenschi, Ricardo F.; France, Marion; Galligan, James J.; Swain, Greg M.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Português
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The electrochemical pretreatment of diamond microelectrodes was investigated for the purpose of learning how an anodic, cathodic or a combined anodic + cathodic polarization affects the charge-transfer kinetics for two surface-sensitive redox systems: ferri/ferrocyanide and serotonin (5-hydroxytryptamine, 5-HT). The pretreatments were performed in 0.5 mol L−1 H2SO4. The anodic pretreatment was performed galvanically for 30 s at 250 mA cm−2. The 10 cathodic pretreatment was performed for 180 s at −250 mA cm−2. The combined pretreatment involved application of the anodic step first followed by the cathodic step. The results clearly demonstrate that the best performance for both redox systems is obtained after the cathodic polarization, which presumably activates the electrode by cleaning the surface and removing site-blocking surface carbon-oxygen functionalities. The cathodic pretreatment was found to be effective at activating a fouled microelectrode in situ. This observation has important implication for the measurement of 5-HT in the bowel.

Measuring minimal residual disease in chronic myeloid leukemia: Fluorescence in situ hybridization and polymerase chain reaction

Hughes, T.; Branford, S.
Fonte: C I G Media Group, L.P. Publicador: C I G Media Group, L.P.
Tipo: Artigo de Revista Científica
Publicado em //2009 Português
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The outlook for newly diagnosed patients with chronic myeloid leukemia (CML) in the imatinib era is excellent for most patients. However, imatinib failure is observed in around 25%-30% of patients. With the availability of second-line tyrosine kinase inhibitor therapy and/or allogeneic transplantation, many of these patients with imatinib failure can still achieve durable cytogenetic and molecular responses. Early evidence of imatinib resistance, when the biology of the emerging leukemia might still be relatively favorable, is the best time to switch to second-line therapy. Close cytogenetic and molecular monitoring will facilitate early intervention in appropriate cases. However, caution should be used when interpreting minimal residual disease data, and the danger of inappropriate changes in therapy based on assay fluctuations should be recognized. A significant increase in the level of BCR-ABL to a level > 0.1% on the international scale (major molecular response) should prompt a repeat BCR-ABL assay, a mutation screen, and possibly marrow cytogenetics. What constitutes a significant increase depends on the laboratory-specific measurement reliability. The possibilities of poor compliance or drug interactions should be considered. If the repeat BCR-ABL assay...

The basis of variation in the size and composition of grape berries

Gray, John D.
Fonte: Universidade de Adelaide Publicador: Universidade de Adelaide
Tipo: Tese de Doutorado
Publicado em //2002 Português
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The objective of this study was to explore the basis of variation in the size and composition of grape berries. The investigation focussed on selected aspects of berry development and ripening that were subject to variation. Shiraz and Chardonnay were chosen as experimental varieties because these cultivars presented a large range of variability in the field – Shiraz is susceptible to variation in colour development at veraison, whereas Chardonnay often displays variation in berry size at harvest. The extent of variation within each of the recorded berry parameters was assessed using the coefficient of variation (CV), a unitless measure of sample variability relative to the sample mean, ideally suited to comparative studies. Chapter 1 is a literature review that documents research on selected aspects of grape berry development and ripening which are subject to variation. Berry development is explained in terms of berry set, berry growth and ovule/seed development. Berry composition is described by the relative concentration of sugars, acids, phenolics and flavour compounds in the berry tissues. Variation is discussed with respect to the Australian wine industry and the problem of supply and demand. Techniques for identifying and measuring components of variation are recommended. Experimental hypotheses are developed. Chapter 2 describes an experiment designed to identify when variation in berry size and composition was initiated. The hypothesis was that relative levels of variation in size and composition would remain constant throughout the postflowering period of berry development. The physical properties of individual Shiraz berries were described in terms of their deformability...

Pessaries in multiple pregnancy as a prevention of preterm birth: the ProTwin trial

Hegeman, M.; Bekedam, D.; Bloemenkamp, K.; Kwee, A.; Papatsonis, D.; van der Post, J.; Lim, A.; Scheepers, L.; Willekes, C.; Duvekot, J.; Spaanderman, M.; Porath, M.; van Eyck, J.; Haak, M.; van Pampus, M.; Bruinse, H.; Mol, B.
Fonte: BioMed Central Publicador: BioMed Central
Tipo: Artigo de Revista Científica
Publicado em //2009 Português
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BACKGROUND Multiple pregnancies are at high risk for preterm birth, and therefore an important cause of infant mortality and morbidity. A pessary is a simple and potentially effective measure for the prevention of preterm birth. Small studies have indicated its effectiveness, but large studies with sufficient power on the subject are lacking. Despite this lack of evidence, the treatment is at present applied by some gynaecologists in The Netherlands. METHODS/DESIGN We aim to investigate the hypothesis that prophylactic use of a cervical pessary will be effective in the prevention of preterm delivery and the neonatal mortality and morbidity resulting from preterm delivery in multiple pregnancy. We will evaluate the costs and effects of this intervention. At study entry, cervical length will be measured. Eligible women will be randomly allocated to receive either a cervical pessary or no intervention. The cervical pessary will be placed in situ at 16 to 20 weeks, and will stay in situ up to 36 weeks gestation or until delivery, whatever comes first. The primary outcome is composite bad neonatal condition (perinatal death or severe morbidity). Secondary outcome measures are time to delivery, preterm birth rate before 32 and 37 weeks, days of admission in neonatal intensive care unit...

Determination and analysis of in situ spectral aerosol optical properties by a multi-instrumental approach

Segura, S.; Estell??s, V.; Titos Vela, Gloria; Lyamani, H.; Utrilla, Mar??a Pilar; Zotter, P.; Pr??vot, A. S. H.; Mo??nik, G.; Alados-Arboledas, Lucas; Mart??nez-Lozano, J. A.
Fonte: Copernicus Publications; European Geosciences Union (EGU) Publicador: Copernicus Publications; European Geosciences Union (EGU)
Tipo: Artigo de Revista Científica
Português
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Continuous in situ measurements of aerosol optical properties were conducted from 29 June to 29 July 2012 in Granada (Spain) with a seven-wavelength Aethalometer, a Multi-Angle Absorption Photometer, and a three-wavelength integrating nephelometer. The aim of this work is to describe a methodology to obtain the absorption coefficients (babs) for the different Aethalometer wavelengths. In this way, data have been compensated using algorithms which best estimate the compensation factors needed. Two empirical factors are used to infer the absorption coefficients from the Aethalometer measurements: C ??? the parameter describing the enhancement of absorption by particles in the filter matrix due to multiple scattering of light in the filter matrix ??? and f, the parameter compensating for non-linear loading effects in the filter matrix. Spectral dependence of f found in this study is not very strong. Values for the campaign lie in the range from 1.15 at 370 nm to 1.11 at 950 nm. Wavelength dependence in C proves to be more important, and also more difficult to calculate. The values obtained span from 3.42 at 370 nm to 4.59 at 950 nm. Furthermore, the temporal evolution of the ??ngstr??m exponent of absorption (??abs) and the single-scattering albedo (??0) is presented. On average ??abs is around 1.1 ?? 0.3...

The ion channel TRPA1 is required for normal mechanosensation and is modulated by algesic stimuli

Brierley, S.; Hughes, P.; Page, A.; Kwan, K.; Martin, C.; O'Donnell, T.; Isaacs, N.; Harrington, A.; Adam, B.; Liebregts, T.; Holtmann, G.; Corey, D.; Rychkov, G.; Blackshaw, L.
Fonte: W B Saunders Co Publicador: W B Saunders Co
Tipo: Artigo de Revista Científica
Publicado em //2009 Português
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BACKGROUND & AIMS: The transient receptor potential (TRP) channel family includes transducers of mechanical and chemical stimuli for visceral sensory neurons. TRP ankyrin 1 (TRPA1) is implicated in inflammatory pain; it interacts with G-protein-coupled receptors, but little is known about its role in the gastrointestinal (GI) tract. Sensory information from the GI tract is conducted via 5 afferent subtypes along 3 pathways. METHODS: Nodose and dorsal root ganglia whose neurons innnervate 3 different regions of the GI tract were analyzed from wild-type and TRPA1(-/-) mice using quantitative reverse-transcription polymerase chain reaction, retrograde labeling, and in situ hybridization. Distal colon sections were analyzed by immunohistochemistry. In vitro electrophysiology and pharmacology studies were performed, and colorectal distension and visceromotor responses were measured. Colitis was induced by administration of trinitrobenzene sulphonic acid. RESULTS: TRPA1 is required for normal mechano- and chemosensory function in specific subsets of vagal, splanchnic, and pelvic afferents. The behavioral responses to noxious colonic distension were substantially reduced in TRPA1(-/-) mice. TRPA1 agonists caused mechanical hypersensitivity...

In situ measurement of the dynamic structure factor in ultracold quantum gases

Weimer, Hendrik; Büchler, Hans Peter
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Português
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We propose an experimental setup to efficiently measure the dynamic structure factor of ultracold quantum gases. Our method uses the interaction of the trapped atomic system with two different cavity modes, which are driven by external laser fields. By measuring the output fields of the cavity the dynamic structure factor of the atomic system can be determined. Contrary to previous approaches the atomic system is not destroyed during the measurement process.; Comment: 5 pages, 3 figures

Simple acoustical technique for automated measurement of drift tube anode wire tension

Hosack, Michael; Coan, Thomas
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Português
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We describe a simple and inexpensive acoustical technique that permits rapid, accurate and in-situ measurement of drift tube anode wire tensions even if the anode wire is electrically discontinuous.; Comment: 5 text pages, 6 figures. fixed typo, minor content change in sec 3

The reliability of cryoSEM for the observation and quantification of xylem embolisms and quantitative analysis of xylem sap in situ.

McCully, Margaret E; Shane, M; Baker, A; Huang, C; Ling, L; Canny, Martin
Fonte: Blackwell Publishing Ltd Publicador: Blackwell Publishing Ltd
Tipo: Artigo de Revista Científica
Português
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The reliability of cryoSEM for visualizing gas embolisms in xylem vessels of intact, functioning roots is examined and discussed. The possibility that these embolisms form as a result of freezing water columns under tension is discounted by a double-freeze experiment. Two regions of the same root, one frozen under tension, the other isolated from the tension by the first freeze, had the same percentage of embolisms, as did also long pieces of root frozen simultaneously along their length. The reliability of energy-dispersive X-ray analysis to measure xylem sap concentration in situ in frozen tissue was established by measurement of KCl standard solution frozen on stubs, and within xylem vessels. Solute heterogeneity within the vessels varied with freezing procedure; deep-freeze > LN2 > cryopliers > liquid ethane, but only the deep-freeze method gave unsatisfactory estimates of concentration for the standard solution. It is concluded that cryoanalytical SEM is useful for direct observation of gas and liquid-filled compartments, and for solute analyses at depth within intact plant organs.

In situ electrochemical-ellipsometry studies of charge-transfer processes at the liquid/liquid interface

Webster, Richard; Beaglehole, D
Fonte: Royal Society of Chemistry Publicador: Royal Society of Chemistry
Tipo: Artigo de Revista Científica
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In situ ellipsometry has been used to characterise the properties of the interface between 1,2-dichloroethane (containing tetrabutylammonium hexafluorophosphate) and water (containing lithium sulfate) during electrochemical potential step (chronoamperometry) experiments with a four-electrode potentiostat. The ellipsometry behaviour was analysed according to changes in the real Δ(rr) and imaginary Δ(ri) signals measured at the Brewster angle during polarisation of the interface between two immiscible electrolyte solutions (ITIES). It was found that both the Δ(rr) and Δ(ri) responses represented relatively slow changes through the interface profile that scaled reversibly with the sign and magnitude of the potential jumps. The ellipsometry responses provided spectroscopic evidence of ion-transfer and accumulation processes via measurement of changes in the refractive index and variation of the dielectric constant in the interface region. The spectroscopic data were consistent with previous models that indicate the ITIES is composed of a mixed solvent layer with varying penetration of electrolyte ion pairs.