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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

The use of surrounding lung parenchyma for the automated classification of pulmonary nodules

Dilger, Samantha Kirsten Nowik 01 May 2013 (has links)
Lung cancer is the leading cause of cancer-related death for both men and women in the United States, despite being the second-most frequent cancer diagnosis for both sexes. This high mortality rate is due to the majority of cases being diagnosed after the primary lung cancer has metastasized. In an effort to reduce mortality associated with lung cancer by diagnosing lung cancer at an earlier stage, screening of high-risk populations has been employed. One screening tool, computed tomography (CT), has been shown to reduce mortality by 20%, compared to screening for lung cancer by chest x-ray. This was achieved by earlier stage diagnosis of lung cancer in participants screened with CT. The use of chest CT in lung cancer screening has also led to increased numbers of false-positives - benign lung nodules that are marked as suspicious for lung cancer. These false-positives result in unnecessary invasive follow-up procedures and costs while incurring additional emotional stress on the patient. In an effort to reduce the number of false-positives, a computer-aided diagnostic (CAD) tool can be designed to determine the probability of malignancy of a lung nodule based on objective measurements. While current CAD models characterize the pulmonary nodule's shape, density, and border, analyzing the parenchyma surrounding the nodule is an area that has been minimally explored. By quantifying characteristics, or features, of the surrounding tissue, this project explores the hypothesis that textural differences in both the nodule and surrounding parenchyma exist between malignant and benign cases. By incorporating these features, performance in the measures of sensitivity, specificity and accuracy can be improved over CAD tools that rely on nodule characteristics alone. A CAD program was developed for the computation of features from a pulmonary nodule. A region of interest containing a nodule and surrounding parenchyma was extracted from a CT scan. Several novel feature extraction techniques were developed, including a three-dimensional application of Laws' Texture Energy Measures to quantify the textures of the parenchyma surrounding the nodule and the nodule itself. In addition, the densities of the nodule and surrounding parenchyma were summarized through metrics such as mean, variance, and entropy of the intensities within each region. Finally, the margins of the nodule were characterized by analyzing mean and variance of border irregularity. A total of 299 features were extracted. To illustrate proof of concept, the CAD program was applied to 27 regions of interest - 10 benign and 17 malignant. Through feature selection, 36 significant features were recognized (p-values < 0.05), including many textural and parenchymal features. These features were further reduced by forward feature selection to two features that summarized the dataset. A neural network was used to classify the cases in a leave-one-out method. Preliminary results yielded 92.6% accuracy in classification of test cases, with two benign nodules incorrectly classified as malignant. The significance of texture and parenchymal features supports the hypothesis that features extracted from the parenchyma have the potential to improve classification of nodules, aiding in the reduction of false-positives identified through CT screening. As more cases are incorporated into the database, these textural features will play a larger role.
22

Respiration and nitrogen fixation by bacteroids from soybean root nodules : substrate transport and metabolism in relation to intracellular conditions

Li, Youzhong, Youzhong.Li@health.gov.au January 2003 (has links)
Bacteroids of B. japonicum from nodules of soybean roots were isolated using differential centrifugation (the standard bench method) and density gradient centrifugation methods (either sucrose- or Percoll-) under anaerobic conditions in which N2 fixation was preserved. The relationships between N2 fixation and respiration, O2 supply, O2 demand, substrate (mainly malate) transport and metabolism in bacteroids were investigated using the flow chamber system. In related experiments, the primary products of N2 fixation which leave the bacteroids were investigated using a 15N-labelling technique in a closed shaken system and other biochemical methods.¶ In the flow chamber experiments, the rates at which O2 was supplied to bacteroids in the chamber were varied by (a) changing the flow rate of reaction medium through the chamber; (b) by changing the [O2 free] in the inflowing reaction medium by using either 3-5% (v/v) or 100% air in the gas mixture above the stirred reaction medium in two reservoir flasks; (c) by successively withdrawing bacteroids from the chamber, thus increasing the supply of O2 per bacteroid to those remaining in the chamber. The results showed that the rate of O2 supply regulates respiratory demand for O2 by bacteroids rather than the O2 concentration present in the reaction system. Respiration is always coupled to N2 fixation. ¶ Uptake of malate by bacteroids withdrawn from the flow chamber was measured under microaerobic conditions. Malate uptake by these N2-fixing bacteroids was lower than that by bacteroids isolated under aerobic conditions, which eliminate N2 fixation of bacteroids, but is closely correlated with bacteroid respiration rates. When respiration was increased by an increase in O2 supply, malate uptake by bacteroids was also increased. This suggested that transport of malate through the bacteroid membrane is also regulated by O2 supply, but indirectly. Higher uptake by bacteroids under aerobic conditions was observed because respiration was enhanced by the high availability of O2, but the fast uptake of malate by bacteroids driven by the abnormal respiration rates may not reflect the reality of malate demand in vivo by bacteroids when N2 fixation by bacteroids is fully coupled. ¶ The results of 15N labelling experiments and other biochemical assays once again demonstrated that ammonia is the principal significant 15N labelled product of N2 fixation accumulated during 30 min in shaken assays with 0.008-0.01 atm O2. Alanine although sometimes found in low concentrations in the flow chamber reactions, was not labelled with 15N in shaken closed system experiments. No evidence could be obtained from the other biochemical assays, either. Therefore, it is concluded that these and earlier results were not due to contamination with host cytosolic enzymes as suggested by Waters et al. (Proc. Natl. Aca. Sci. 95, 1998, pp 12038-12042). ¶ Malate transported into bacteroids is oxidized in a modified TCA cycle present in bacteroids. The results of flow chamber experiments with a sucA mutant (lacking a-ketoglutarate dehydrogenase) showed that respiratory demand for O2 by the mutant bacteroids is regulated by O2 supply in the same way as the wild-type. Despite differences in other symbiotic properties, rates of nitrogen fixation by the mutant bacteroids, based on the bacteroid dry weight, appeared to be the same as in the wild-type. Also N2 fixation was closely coupled with respiration in the same manner in both mutant bacteroids and wild type bacteroids. These results and other supporting data, strongly support the conclusion that there is an alternative pathway of the TCA cycle in bacteroids, which enables the missing step in the mutant to be by-passed with sufficient activity to support metabolism of transported malate.
23

Biologinio azoto susikaupimas agrocenozėse / Aceumulation of biological nitrogen in agrocenoses

Plioplytė, Kristina 15 June 2009 (has links)
Tiriamojo darbo objektas - tirtos daugiamečių žolių veislės: raudonieji dobilai ‘Liepsna’, baltieji dobilai ‘Bitūnai’ ir rausvieji dobilai “Daubiai“, pasėti mišinyje su varpinėmis žolėmis: pašariniais motiejukais, tikraisiais eraičinais, daugiametėmis svidrėmis , pievinėmis miglėmis. Tyrimo tikslas – 1. nustatyti Rizobakterijų gumbelių skaičiuų ir masę skirtingose ankštinėse žolėse; 2. nustatyti biologinio azoto sukaupimą žolynų agrocenozėse. Tyrimo metodika. Tyrimai buvo vykdyti 2008 m. Lietuvos žemės ūkio universiteto bandymų stotyje ir Vėžaičiuose įvairiuose laukuose, kurių tikslios charakteristikos nepavyko sužinoti. Iš kiekvieno lauko paimti ir iškasti 10 augalų su šaknimis: 10 raudonųjų dobilų (Trifolium pratense L), 10 baltųjų dobilų (Trifolium repens L.) ir 10 rausvųjų dobilų (Trifolium hybridum L). Paimti augalai atsargiai nuplauti ir suskaičiuoti ant kiekvieno augalo šaknų esantys gumbeliai. Suskaičiuoti gumbeliai pasverti. Gumbelių analizė atlikta dobilų žydėjimo metu. Laikėme, kad m-2 buvo 10 augalų. Rhizobakterijų gumbelių skaičius hektare paskaičiuotas vnt.m-2 padauginus iš 10000. Tyrimo rezultatai. 1. Vidutiniais duomenimis daugiausiai (102 vnt.) gumbelių priskaičiuota ant raudonųjų dobilų šaknų, mažiau (97 vnt.) ant baltųjų dobilų ir mažiausiai (72 vnt.) ant rausvųjų dobilų šaknų. Rhizobakterijų gumbelių masė ant skirtingų dobilų rūšių šaknų įvairavo 0,03-0,05 g ribose. 2. Tarp visų dobilų rūšių gumbelių skaičiaus ir jų masės nustatytas stiprus koreliacinis... [toliau žr. visą tekstą] / The aim of investigation was to determine number and weight of nodules formed on the roots of varios perennial leguminous grasses. 1. The highest midle number 102 of Rhizobacterial nodules was determined on red clover roots. On the roots of whete 97 clover were less Rhizobacterial nodules and the least Rhizobacterial nodules number 72 defined on alsike clover roots. 2. The weight of Rhizobacterial nodules on different clover species roots difered between 0,03 – 0,05 g.
24

Identification and characterization of GmCaMK1: a novel calmodulin-binding receptor-like kinase from nodules of soybean (Glycine max)

DEFALCO, THOMAS A 03 February 2010 (has links)
Ca2+ functions as a second messenger in all eukaryotes. Such Ca2+ signaling is used to coordinate plant responses to numerous stimuli, both developmental and environmental. Ca2+ signals are often transduced via the action of the ubiquitous Ca2+ sensor calmodulin (CaM). CaM-dependent protein phosphorylation forms an important component of such signal transduction pathways, including that regulating the initiation and development of symbiotic rhizobial nodules in legumes such as soybean (Glycine max). To further understand the role of Ca2+/CaM during nodule organogenesis, a nodule cDNA expression library was screened using radiolabeled CaM as a probe to identify novel CaM-binding proteins (CaMBPs). This screen resulted in the identification of a previously uncharacterized receptor-like kinase, termed GmCaMK1. The CaM-binding domain (CaMBD) of GmCaMK1 is located in a 24 residue region of GmCaMK1, which overlaps with the subdomain XI of a conserved Ser/Thr kinase domain. This CaMBD bound CaM in a Ca2+-dependent manner, and with high affinity (Kd = 1.4 nM). Furthermore, two hydrophobic residues (V372 and L375) were identified as critical for GmCaMK1-CaM interaction. Recombinant GmCaMK1 exhibited protein kinase activity in vitro, with autophosphorylation activity unaffected by the presence or absence of Ca2+/CaM. GmCaMK1 expression is enriched in developing nodules and main roots, and highest expression level was observed in lateral roots. While the function of CaM-binding to GmCaMK1 remains unclear, the affinity and Ca2+-dependence of the GmCaMK1-CaM interaction strongly suggests that GmCaMK1 is a physiologically relevant CaM target. The Arabidopsis ortholog of GmCaMK1, AtCaMK1 also bound CaM when expressed as a recombinant protein. GmCaMK1 is part of a multi-member family in soybean, as are putative homologs across taxa, suggesting that this is a novel, conserved family of CaMBPs. / Thesis (Master, Biology) -- Queen's University, 2010-01-28 16:00:48.69
25

Marine sedimentation and manganese nodule formation in the southwestern Pacific Ocean

Meylan, Maurice A January 1978 (has links)
Photocopy of typescript. / Thesis (Ph. D.)--University of Hawaii at Manoa, 1978. / Bibliography: leaves 219-235. / Microfiche. / xiii, 311 leaves ill., maps
26

Detection of protease and protease inhibitors during development of soybean crown nodules

Mashamba, Lufuno Abigail 23 November 2010 (has links)
A symbiotic association between leguminous roots and soil fixing nitrogen bacteria is required for legume nodule formation. The primary function of nodules is the fixation of nitrogen from the atmosphere into an accessible form for plants. In this study, nodules of plants of the soybean cultivar Prima 2000 were characterized and their number and weight were determined during nodule development. Their nitrogen-fixing activity during nodule development was determined by color evaluation. A pink nodule color showed active leghemoglobin required for nitrogen fixation and a green nodule color nonfunctional leghemoglobin. Strong appearance of nonfunctional leghemoglobin in the later stages of nodule development during senescence was accompanied by an increase in protease activity within crown nodules demonstrated by gelatine-containing SDS PAGE. Cysteine protease activity was identified as a major protease activity during nodule senescence when the cysteine protease inhibitor E-64 was used to block total protease activity. Products, which may indicate the expression of cysteine protease inhibitors during nodule development, were detected with the reverse zymogram technique and Western blotting. However, these bands have not been characterized so far in more detail. Putative transgenic plants were produced using the Agrobacterium transformation technique to allow determining the activity of native and mutated papaya cysteine protease inhibitor coding sequences. These sequences will ultimately be used for soybean transformation to reduce cysteine protease activity in nodules. However, the presence of coding sequence in the genome of these putative transgenic plants could not be confirmed by gene amplification and protease activity testing. Overall, this study has contributed to establish parameters to measure nodule growth and performance during development. / Dissertation (MSc)--University of Pretoria, 2010. / Plant Science / unrestricted
27

Syntheses and magnetic studies of manganese(II) monophenylphosphinates and some cadmium(II) doped compounds

Du, Jing-Long January 1987 (has links)
Anhydrous monophenylphosphinates of manganese(II), Mn[H(C₆H₅)PO₂]₂ (Form I, Form II and Form 1(B)) and cadmium(II), Cd[H(C₆H₅)PO₂]₂ (Form I and Form II) were synthesized and characterized by solubility tests, Differential Scanning Calorimetry (DSC), Infrared Spectroscopy, X-ray Powder Diffractometry, Electron Spin Resonance (ESR) spectroscopy, magnetic susceptibility measurements and Electron Spectroscopy for Chemical Analysis (ESCA). These materials are considered to be polymeric with metal ions connected in chains by double bridging phosphinate groups with cross-linkage forming sheets and octahedral metal centers. Magnetic susceptibility studies showed that Mn[H(C₆H₅)PO₂]₂ (Form I) exhibits relatively strong antiferromagnetic exchange interactions (J is about -4.50 cm⁻¹) and the effects on this magnetic exchange of doping diamagnetic cadmium ions into the material have been investigated. A series of mixed metal phosphinates of the form Mn₁₋x Cdx [H(C₆H₅)PO₂]₂ (Form I) where x=0 to 1.00 were prepared and investigated. The effect of doping with cadmium is to break the infinite manganese(II) monophenylphosphinate chain into finite segments and to generate monomer impurities in odd numbered segments. As the extent of doping is increased the average chain length decreases and the fraction of monomer increases. In addition, the exchange coupling constant, J, was found to decrease (from -4.50 to -2.70 cm⁻¹) as the average chain length decreases. Mn[H(C₆H₅)PO₂]₂ (Form 1(B)), which is precipitated from concentrated solutions, contains much shorter chain fragments than the pure Form I material. Mn[H(C₆H₅)PO₂]₂ (Form II) has a distinct infrared spectrum and X-ray powder diffraction pattern and shows much weaker antiferromagnetic behavior (J is about -2.40 cm⁻¹) than the Form I compound. Magnetic studies suggest that in this compound the average chain length is significantly smaller than in Mn[H(C₆H₅)PO₂]₂ (Form I). The hydrated monophenylphosphinates of manganese(II), Mn[H(C₆H₅)PO₂]₂•H₂0 and Mn[H(C₆H₅)PO₂]₂•2H₂0, were synthesized and characterized in this work. The structures of these compounds are considered to be similar to those of the anhydrous materials except in the hydrated compounds one or two of the metal coordination sites are occupied by water molecules. The dihydrate shows only very weak antiferromagnetic properties (J is about -0.50 cm⁻¹). The diphenylphosphinates of manganese(II) and cadmium(II) were also prepared and characterized. The infrared spectra and X-ray powder diffraction patterns for these materials are distinct from each other,which indicates the compounds are not isomorphous. Only rather weak magnetic exchange was observed in the manganese compound. Zn[H(C₆H₅)PO₂]₂ has also been synthesized and partially characterized in this work. The infrared spectrum and X-ray powder diffraction pattern obtained for this compound are unique among all the metal phosphinates studied in this work. / Science, Faculty of / Chemistry, Department of / Graduate
28

In vitro bone-like nodules generated from patient-derived iPSCs recapitulate pathological bone phenotypes / iPS細胞からのin vitro骨様結節形成と骨疾患病態再現への応用

Kawai, Shunsuke 23 January 2020 (has links)
京都大学 / 0048 / 新制・課程博士 / 博士(医学) / 甲第22143号 / 医博第4534号 / 新制||医||1039(附属図書館) / 京都大学大学院医学研究科医学専攻 / (主査)教授 妻木 範行, 教授 森本 尚樹, 教授 別所 和久 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM
29

recognition and Incision of Oxidative Intrastrand Cross-Link Lesions by UvrABC Nuclease

Mattar, Costy, Keith, Rob L., Byrd, Ryland P., Roy, Thomas M. 01 August 2006 (has links)
Septic pulmonary embolization (SPE) is a rare but serious disorder. It is a well-recognized potential problem in the settings of tricuspid valve endocarditis, septic thrombophlebitis, infected central venous catheters, and postanginal septicemia. Less well documented is the occurrence of SPE in patients with periodontal disease without suppurative thrombophlebitis of the great vessels of the neck. We report a patient with SPE in whom periodontal disease was the only identifiable nidus of infection and review the literature regarding the four other patients reported to have suffered this complication.
30

TOWARDS THE MINIMAL SYMBIOTIC GENOME OF SINORHIZOBIUM MELILOTI

Huang, Jiarui January 2019 (has links)
Sinorhizobium meliloti is a model bacterium for the study of symbiotic nitrogen fixation (SNF). It infects the roots of alfalfa as well as some other legumes and differentiates into N2-fixing bacteroids within the plant cells of specialized nodule organs. To understand genes essential for SNF and, in the longer term, to facilitate the manipulation of this SNF process for agricultural purposes, it is highly desirable to construct the minimal genome for SNF in this organism. S. meliloti harbors two replicons required for SNF, a 1.7-Mb chromid (pSymB) and a 1.4-Mb megaplasmid (pSymA). A previous deletion analysis revealed that only four gene regions, accounting for <12% of the total sequences of pSymA and pSymB that, were essential for SNF. In the first part of the thesis, I report the cloning of these two pSymA SNF-essential regions on a plasmid (pTH3255) in Escherichia coli, and the integration of this plasmid into the genome of a ∆pSymA S. meliloti derivative strain (the strain was named as RmP4291 after integration). Plant root dry weight and nitrogenase-catalyzed acetylene reduction assays were carried out on RmP4291 with four host plants, including Medicago sativa, Medicago truncatula, Melilotus alba and Melilotus officinalis. Nodule kinetic assays were also performed on RmP4291 and RmP110(wt). The results showed that the SNF-essential regions from pSymA were sufficient to restore the symbiotic capabilities to the ∆pSymA derivative strain with all the host plants tested, except a significant reduction (~40%) in SNF by RmP4291 was noticed on M. officinalis compared to that by wildtype S. meliloti. A higher alfalfa nodulation efficiency of RmP4291 compared to that of wildtype RmP110 was also discovered. In the second part of the thesis, a histochemical staining method for S. meliloti nodules was developed by integrating the marker genes gusA (β-glucuronidase) and celB (β-glucosidase) into the S. meliloti genome. This staining method was found to be useful in the study of nodule competitiveness. A nodule competition assay was carried out between RmP4291 and RmP110 using the new staining method. RmP4291 was found to be significantly reduced in nodulation competitiveness compared to wildtype S. meliloti. The development of the histochemical staining method for S. meliloti nodules will accelerate the identification of genes required for nodule competitiveness in the organism, which will be of crucial importance to the construction of the minimal genome strains with high SNF efficiency. / Thesis / Master of Science (MSc) / Nitrogen is one of the critical elements for life. Biological nitrogen fixation plays a crucial role in providing fixed nitrogen for the ecosystem on Earth. Our Laboratory has endeavored to establish a minimal symbiotic genome in Sinorhizobium meliloti, a model nitrogen fixing bacterium which forms symbiosis with certain kinds of legumes. Building this minimal symbiotic genome will improve our understanding of the symbiotic nitrogen fixation process in S. meliloti at gene level. It may also help in eventually introducing a nitrogen fixation system into other organisms. In this study, the minimal symbiotic genome of the pSymA replicon in S. meliloti was constructed. In addition, a staining method to detect specific S. meliloti strains in nodules was established. This method is potentially useful in finding genes related to nodule competitiveness, and these are potentially important for augmenting the genes that constitute the minimal symbiotic genome.

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