138 research outputs found
Measurement of species flux from a bubble using an acousto-electrochemical technique
An acousto-electrochemical technique is presented which, for the first time, offers the potential for measuring the flux of dissolved species in a liquid resulting from bubbles of a specific chosen size in the population. Laboratory trials are presented, but the device itself was damaged in the surf zone and no data was obtained from the ocean deployment. Nevertheless, the preceding laboratory tests demonstrate the viability of the technique. The device responds to perturbations of the fluid around a small electrode. Three such sources of motion must be characterised if it is to achieve the objective stated above. First, the perturbations resulting form the translatory motions of bubbles in the liquid. To obtain bubble radius resolution in the measurement of mass flux, however, it is necessary to apply to driving (‘pump’) sound field. Bubbles close to resonance will, in addition to a translatory motion, impart to the liquid a component of mass flux at the pump frequency. This is detected. However to show that this is the result of bubble wall pulsation, and not someother coupling, the amplitude of the pump field is increased until the electrochemical sensor detects Faraday waves on the bubble wall. Not only does this prove the relation between mass flux to bubble wall motion, it provides a second route by which the radius-resolved component of mass flux might be identified. In these preliminary laboratory tests, electrochemical detection of these motions was achieved through the observation of current produced by the reduction of a suitable redox agent present within the liquid phase of the solution employed. Preparations were made to obtain preliminary data from the Hurst Spit 2000 surf zone trial, but the device was damaged by the environment
Ratios of Elastic Scattering of Pions from 3H and 3He
We have measured the elastic-scattering ratios of normalized yields for
charged pions from 3H and 3He in the backward hemisphere. At 180 MeV, we
completed the angular distribution begun with our earlier measurements, adding
six data points in the angular range of 119 deg to 169 deg in the pi-nucleus
center of mass. We also measured an excitation function with data points at
142, 180, 220, and 256 MeV incident pion energy at the largest achievable angle
for each energy between 160 deg and 170 deg in the pi-nucleus center of mass.
This excitation function corresponds to the energies of our forward-hemisphere
studies. The data, taken as a whole, show an apparent role reversal of the two
charge-symmetric ratios r1 and r2 in the backward hemisphere. Also, for data >
100 deg we observe a strong dependence on the four-momentum transfer squared
(-t) for all of the ratios regardless of pion energy or scattering angle, and
we find that the superratio R data match very well with calculations based on
the forward-hemisphere data that predicts the value of the difference between
the even-nucleon radii of 3H and 3He. Comparisons are also made with recent
calculations incorporating different wave functions and double scattering
models.Comment: RevTex 8pages, 12 figure file
On the Reliability of Meta-Analytic Reviews
The article addresses the issue of intercoder reliability in meta-analyses. The current practice of reporting a single, mean intercoder agreement score in meta-analytic research leads to systematic bias and overestimates the true reliability. An alternative approach is recommended in which average intercoder agreement scores or other reliability statistics are calculated within clusters of coded variables. These clusters form a hierarchy in which the correctness of coding decisions at a given level of the hierarchy is contingent on decisions made at higher levels. Two separate studies of intercoder agreement in meta-analysis are presented to assess the validity of the model.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/67840/2/10.1177_0193841X9301700303.pd
Female reproductive life span is extended by targeted removal of fibrotic collagen from the mouse ovary.
The female ovary contains a finite number of oocytes, and their release at ovulation becomes sporadic and dis-ordered with aging and with obesity, leading to loss of fertility. Understanding the molecular defects underpinning this pathology is essential as age of childbearing and obesity rates increase globally. We identify that fibrosis within the ovarian stromal compartment is an underlying mechanism responsible for impaired oocyte release, which is initiated by mitochondrial dysfunction leading to diminished bioenergetics, oxidative damage, inflam-mation, and collagen deposition. Furthermore, antifibrosis drugs (pirfenidone and BGP-15) eliminate fibrotic collagen and restore ovulation in reproductively old and obese mice, in association with dampened M2 macro-phage polarization and up-regulated MMP13 protease. This is the first evidence that ovarian fibrosis is reversible and indicates that drugs targeting mitochondrial metabolism may be a viable therapeutic strategy for women with metabolic disorders or advancing age to maintain ovarian function and extend fertility.Takashi Umehara, Yasmyn E. Winstanley, Eryk Andreas, Atsushi Morimoto, Elisha J. Williams, Kirsten M. Smith, John Carroll, Mark A. Febbraio, Masayuki Shimada, Darryl L. Russell, Rebecca L. Robke
Physics of Solar Prominences: I - Spectral Diagnostics and Non-LTE Modelling
This review paper outlines background information and covers recent advances
made via the analysis of spectra and images of prominence plasma and the
increased sophistication of non-LTE (ie when there is a departure from Local
Thermodynamic Equilibrium) radiative transfer models. We first describe the
spectral inversion techniques that have been used to infer the plasma
parameters important for the general properties of the prominence plasma in
both its cool core and the hotter prominence-corona transition region. We also
review studies devoted to the observation of bulk motions of the prominence
plasma and to the determination of prominence mass. However, a simple inversion
of spectroscopic data usually fails when the lines become optically thick at
certain wavelengths. Therefore, complex non-LTE models become necessary. We
thus present the basics of non-LTE radiative transfer theory and the associated
multi-level radiative transfer problems. The main results of one- and
two-dimensional models of the prominences and their fine-structures are
presented. We then discuss the energy balance in various prominence models.
Finally, we outline the outstanding observational and theoretical questions,
and the directions for future progress in our understanding of solar
prominences.Comment: 96 pages, 37 figures, Space Science Reviews. Some figures may have a
better resolution in the published version. New version reflects minor
changes brought after proof editin
Variação de matéria seca e de nutrientes nas folhas e nos frutos, produção de ácido ascórbico e suco, em seis cultivares de citros, durante um ciclo
De uma plantação de citros, com os cultivares T. Cravo (Citrus reticulata Blanco), L.Hamlin (Citrus sinensis (L.) Osbeck), T. Murcott (Citrus reticulata Blanco x Citrus sinensis (L.) Osbeck), L. Natal (Citrus sinensis (L.) Osbeck, L. Valencia (Citrus sinensis (L.) Osbeck) e L. Pera (Citrus sinensis (L.) Osbeck), situada na "Fazenda Sete Lagoas", no município de Mogi-Guaçu (22° 22% 46° 56'W.Gr.), em Latossolo Vermelho amarelo, fase arenosa, foram coletados frutos 30 dias após florescimento, até a idade da coleta comercial. No material coletado, foram determinadas a variação da matéria seca, a concentração dos macro e micronutrientes nas folhas adjacentes ao fruto, a extração de macro e micronutríentes pelos frutos, a produção de suco (ml) por fruto e a concentração de ácido ascórbico (mg/100 ml de suco). Concluiu-se que: 1. O aumento da matéria seca, intensifica-se a partir do segundo mês apos o florescimento; 2. Com exceção da T. Cravo, ocorre uma diminuição na produção de matéria seca no final do ciclo; 3. A concentração dos macro e micronutrientes nas folhas apresenta oscilações durante o desenvolvimento do fruto; 4. A ordem decrescente de extração de nutrientes é: K, N, Ca, Mg, P = S, Fe, B, Zn, Mn, Cu; 5. A capacidade de exportação de nutrientes pelos cultivares é, em ordem decrescente: L. Pera, L. Hamlin = T. Cravo, T. Murcott, L. Valencia, L. Natal; 6. A quantidade de suco produzido por fruto, oscila entre 43 a 95 ml; 7. A concentração de ácido ascórbico (mg/100 ml de suco), varia entre 30 a 95
Pilot Study of [18F] Fluorodeoxyglucose Positron Emission Tomography (FDG-PET)/Magnetic Resonance Imaging (MRI) for Staging of Muscle-invasive Bladder Cancer (MIBC)
Introduction: Computed tomography (CT) has limited diagnostic accuracy for staging of muscle-invasive bladder cancer (MIBC). [18F] Fluorodeoxyglucose positron emission tomography (FDG-PET)/magnetic resonance imaging (MRI) is a novel imaging modality incorporating functional imaging with improved soft tissue characterization. This pilot study evaluated the use of preoperative FDG-PET/MRI for staging of MIBC. Patients and Methods: Twenty-one patients with MIBC with planned radical cystectomy were enrolled. Two teams of radiologists reviewed FDG-PET/MRI scans to determine: (1) presence of primary bladder tumor; and (2) lymph node involvement and distant metastases. FDG-PET/MRI was compared with cystectomy pathology and computed tomography (CT). Results: Eighteen patients were included in the final analysis, most (72.2%) of whom received neoadjuvant chemotherapy. Final pathology revealed 10 (56%) patients with muscle invasion and only 3 (17%) patients with lymph node involvement. Clustered analysis of FDG-PET/MRI radiology team reads revealed a sensitivity of 0.80 and a specificity of 0.56 for detection of the primary tumor with a sensitivity of 0 and a specificity of 1.00 for detection of lymph node involvement when compared with cystectomy pathology. CT imaging demonstrated similar rates in evaluation of the primary tumor (sensitivity, 0.91; specificity, 0.43) and lymph node involvement (sensitivity, 0; specificity, 0.93) when compared with pathology. Conclusions: This pilot single-institution experience of FDG-PET/MRI for preoperative staging of MIBC performed similar to CT for the detection of the primary tumor; however, the determination of lymph node status was limited by few patients with true pathologic lymph node involvement. Further studies are needed to evaluate the potential role for FDG-PET/MRI in the staging of MIBC. © 2020 Elsevier Inc.In this pilot study, preoperative staging with [18F] fluorodeoxyglucose-positron emission tomography/magnetic resonance imaging in muscle-invasive bladder cancer detected the primary bladder tumor; however, the determination of lymph node status was limited by few patients with pathologic lymph node involvement. Additional studies are needed to evaluate the potential role for [18F] fluorodeoxyglucose-positron emission tomography/magnetic resonance imaging in the staging of bladder cancer
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