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Estudo da relaxação dielétrica de filmes ultrafinos de poliestireno sulfonado; Dielectric relaxation studies of ultrathin film of sulfonated polystyrene

Sousa, Washington da Silva
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 30/06/2009 PT
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Ionômeros são polímeros carregados que possuem uma variedade de propriedades elétricas e que recentemente vêm sendo aplicados como camadas de transporte em dispositivos poliméricos. Em particular, camadas ultrafinas de ionômeros são depositadas entre o eletrodo e o polímero eletrônico em OLEDs para aumentar a eficiência da injeção de cargas. Entretanto o sucesso desta aplicação envolve fenômenos de armazenamento e mecanismos de transportes de cargas dentro do ionômero que ainda não são claramente entendidos. Neste trabalho foi utilizada a técnica da corrente despolarização termoestimulada (TSDC) com o propósito de esclarecer alguns efeitos relacionados a esse fenômeno. Nós utilizamos o poliestireno sulfonado (X-SPS) com lítio (X = Li) ou potássio (X = K) como contraíon. Foram obtidos filmes ultrafinos com 50 nm de espessura por spincoating obtendo a estrutura metal-polímero-metal para estudo, tendo como metal o alumínio. A técnica de TSDC consiste no aquecimento de uma amostra previamente polarizada a um taxa de aquecimento constante e a corrente de despolarização é medida em função da temperatura da amostra. Os resultados experimentais mostraram que cada termograma apresenta dois picos, sendo que um dos deles mostrou-se fortemente dependente das condições de polarização...

Vesicle-micelle transition in mixtures of dioctadecyldimethylammonium chloride and bromide with nonionic and zwitterionic surfactants

Feitosa, E.; Bonassi, N. A.; Loh, W.
Fonte: Amer Chemical Soc Publicador: Amer Chemical Soc
Tipo: Artigo de Revista Científica Formato: 4512-4517
ENG
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We have investigated the effect of mixing spontaneously formed dispersions of the cationic vesicle-forming dioctadecyldimethylammonium chloride and bromide (DODAX, with X being anions Cl- (C) or Br- (B)) with solutions of the micelle-forming nonionic ethylene oxide surfactants penta-, hepta-, and octaethyleneglycol mono-n-dodecyl ether, C12En (n = 5, 7, and 8), and the zwitterionic 3-(N-hexadecyl-N,N-dimethylammonio)propane sulfonate (HPS). We used for this purpose differential scanning calorimetry (DSC), turbidity, and steady-state fluorescence spectroscopy to investigate the vesicle-micelle (V-M) transition yielded by adding C12En and HPS to 1.0 mM vesicle dispersions of DODAC and DODAB. The addition of these surfactants lowers the gel-to-liquid crystalline phase transition temperature (T-m) of DODAC and DODAB, and the transition becomes less cooperative, that is, the thermogram transition peak shifts to lower temperature and broadens to disappear when the V-M transition is complete, the vesicle bilayer becomes less organized, and the T., decreases, in agreement with measurements of the fluorescence quantum yield of trans-diphenylpolyene (t-DPO) fluorescence molecules incorporated in the vesicle bilayer. Turbidity data indicate that the V-M transition comes about in three stages: first surfactants are solubilized into the vesicle bilayer; after saturation...

Especiação de mercurio em solos contaminados por analise de termodessorção acoplada a absorção atomica

Claudia Carvalhinho Windmoller
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em //1996 PT
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Um sistema de termodessorção de mercúrio de amostras sólidas foi desenvolvido, e suas condições operacionais foram otimizadas. Este consiste basicamente de um forno (um tubo de quartzo envolto por uma bobina de NiCr), acoplado a um espectrofotômetro de absorção atômica (AAS), o qual fornece termogramas das amostras analisadas, ou seja, registros de absorbância em função de temperatura. Esse sistema, chamado TDAAS, foi utilizado para a análise dos seguintes padrões de mercúrio: Hg, Hg2Cl2, HgCI2, HgO e HgS, os quais foram aplicados a dois tipos diferentes de solo. Estes mostraram perfis de termodessorção bastante semelhantes nas duas matrizes, porém diferentes faixas de termodessorção entre si, indicando a possibilidade de aplicação do método na especiação de mercúrio em solos. Amostras de solo contaminadas com mercúrio, provenientes de garimpos da cidade de Poconé, Mato Grosso, Brasil (amostras BRA), e de uma produção eletrolítica de cloro/soda, na região do Halle, Alemanha (amostras GER), analisadas por TDAAS, mostraram que o Hg, principal forma de contaminação em ambos os casos, sofre oxidação. Essa oxidação ocorre em maior extensão nas amostras provenientes da Alemanha, as quais contêm altas concentrações de íons cloreto...

Extração e estrutura dos polissacarídeos do resíduo do café com atividade imunoestimuladora

Simões, Joana Sá Ramalho
Fonte: Universidade de Aveiro Publicador: Universidade de Aveiro
Tipo: Tese de Doutorado
ENG
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As galactomananas das infusões de café apresentam atividade imunoestimuladora in vitro, sendo esta atividade semelhante à das mananas acetiladas extraídas de Aloe vera. As galactomananas presentes no resíduo de café também possuem atividade imunoestimuladora in vitro quando são parcialmente acetiladas. Como as galactomananas são o componente maioritário do resíduo de café e como o café é um produto de largo consumo a nível mundial, o reaproveitamento deste resíduo como fonte de galactomananas com atividade imunoestimuladora deve ser considerado. Esta dissertação procura dar resposta a duas questões: 1. Quais são as estruturas das galactomananas responsáveis pela atividade imunoestimuladora destes polissacarídeos; e 2. Como é que as galactomananas podem ser extraídas quantitativamente do resíduo de café de modo a serem solúveis em água à temperatura ambiente e, assim, poderem ser utilizadas como ingredientes alimentares com atividade imunoestimuladora. A questão 1 foi respondida pela caracterização estrutural de quatro galactomananas, de três origens: a) as galactomananas das infusões de café e do resíduo que apresentaram atividade imunoestimuladora; b) a galactomanana da goma de alfarroba (LBG), que não apresentou atividade imunoestimuladora; e c) a manana acetilada de Aloe vera...

Aerobic growth thermograms of Streptococcus lactis obtained with a complex medium containing glucose.

Monk, P R
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /08/1978 EN
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With different culturing methods both simple and complex thermograms were obtained with Streptococcus lactis grown aerobically in a complex medium containing growth-limiting concentrations of glucose. The thermogram profiles have been interpreted in relation to growth rate, glucose degradation, and molar growth yields calculated for different time intervals during growth.

Use of Differential Scanning Calorimetry for Structural Analysis of Fungally Degraded Wood

Reh, Ursula; Kraepelin, Gunda; Lamprecht, Ingolf
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /11/1986 EN
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This paper assesses the potential use of differential scanning calorimetry for analyzing sound and decayed wood. With sound wood, this method permitted the detection of cellulose, hemicellulose, and lignin components as discrete peaks of combustion at defined temperatures. Characteristic changes in the calorimetric thermogram of birchwood (temperature of maxima, peak height, and peak area) were obtained from wood samples degraded by the basidiomycetes Fomes fomentarius and Piptoporus betulinus. Additional peaks in the thermograms of white rotted birchwood were assigned to lignin degradation products and to mycelium. Results obtained by the differential scanning calorimetry method are compared with those of chemical determination, with particular emphasis on Klason lignin.

Direct measurement of the melting temperature of supported DNA by electrochemical method

Meunier-Prest, Rita; Raveau, Suzanne; Finot, Eric; Legay, Guillaume; Cherkaoui-Malki, Mustapha; Latruffe, Norbert
Fonte: Oxford University Press Publicador: Oxford University Press
Tipo: Artigo de Revista Científica
Publicado em 01/12/2003 EN
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The development of biosensors based on DNA hybridization requires a more precise knowledge of the thermodynamics of the hybridization at a solid interface. In particular, the selectivity of hybridization can be affected by a lot of parameters such as the single-strand (ss)DNA density, the pH, the ionic strength or the temperature. The melting temperature, Tm, is in part a function of the ionic strength and of the temperature and therefore provides a useful variable in the control of the selectivity and sensitivity of a DNA chip. The electrochemical technique has been used to determine the Tm values when the probe is tethered by a DNA self-assembled monolayer (SAM). We have built a special thin layer cell, which allows the recording of the cyclic voltammogram under controlled temperature conditions. Tm has been determined by recording the thermogram (current versus temperature) of a redox indicator on a double-stranded hybrid (dsDNA) modified electrode and comparison with the corresponding ssDNA response. Tm of supported DNA varies linearly with the ionic strength. The stability of the SAMs has been considered and comparison between Tm in solution and on a solid support has been discussed.

Thermography in screening for breast cancer.

Williams, K L; Phillips, B H; Jones, P A; Beaman, S A; Fleming, P J
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /06/1990 EN
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STUDY OBJECTIVE--The aim of the study was to determine whether thermography could be used to identify women with breast cancer or women at risk of developing the disease within five years. DESIGN--Women were screened for breast cancer and a documentary follow up was conducted five years later through general practitioner records. SETTING--The project involved Women resident in the Bath District Health Authority area, who were invited to attend a breast screening clinic. SUBJECTS--10,238 women aged between 40 and 65 were screened. Of these, 4284 accepted personal letters of invitation from their general practitioners and 5954 volunteered to take part in the project in response to publicity; 9819 (96.5%) were traced after five years. MEASUREMENTS AND MAIN RESULTS--All the women had a thermographic and clinical examination of their breasts. If either examination was abnormal they were referred for mammography. Sensitivity of thermography was found to be 61% and specificity 74%. A documentary follow up of each woman was conducted five years later, when it was found that 71.6% of the women who developed breast cancer had had a normal thermogram at the time of examination, as did 73% of those who did not. CONCLUSIONS--Thermography is not sufficiently sensitive to be used as a screening test for breast cancer...

Test sequences in screening for breast cancer.

Siu, T O; Hancock, J R
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em //1977 EN
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Published data of Stark and Way on the screening of 2,684 women at high risk of breast cancer are analyzed to arrive at a preferred sequence of screening tests. In the practical situation where palpation first signals a problem, the analysis suggests thermography to follow. Women with positive thermograms should then be biopsied, and those with negative thermograms should be mammographed. A positive mammogram calls for biopsy, and a negative one calls for close follow-up. For high-risk women whose breasts appear normal on palpation, a subsequent negative thermogram is not definitive enough to terminate investigation, but a negative mammogram after a negative palpation is enough evidence to waive further investigation for some time. A positive mammogram calls for immediate biopsy in any circumstance.

Different modes of interaction of pulmonary surfactant protein SP-B in phosphatidylcholine bilayers.

Cruz, A; Casals, C; Keough, K M; Pérez-Gil, J
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em 01/10/1997 EN
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Pulmonary surfactant-associated protein B (SP-B) has been incorporated into vesicles of dipalmitoyl phosphatidylcholine (DPPC) or egg yolk phosphatidylcholine (PC) by two different procedures to characterize the dependence of lipid-protein interactions on the method of reconstitution. In method A the protein was dissolved in a small volume of either methanol or 60% (v/v) acetonitrile and injected into an aqueous phase containing phospholipid vesicles. In method B the vesicles were prepared by injection of a mixture of phospholipid and SP-B dissolved in methanol or aqueous acetonitrile. Both methods of reconstitution led to the extensive interaction of SP-B with PC bilayers as demonstrated by co-migration during centrifugation, marked protection against proteolysis, change in the fluorescence emission intensity of SP-B, and protection of SP-B tryptophan fluorescence from quenching by acrylamide. SP-B promoted the rapid adsorption of DPPC on an air/liquid interface irrespective of the method of protein reconstitution. However, the interfacial adsorption activity of SP-B reconstituted by method B remained stable for hours, but that of SP-B prepared by method A decreased with time. Electron microscopy showed that the injection of SP-B into an aqueous phase containing PC or DPPC vesicles (method A) induced a rapid aggregation of vesicles. By contrast...

Chromatin changes in cell transformation: progressive unfolding of the higher-order structure during the evolution of rat hepatocyte nodules. A differential scanning calorimetry study.

Barboro, P.; Pasini, A.; Parodi, S.; Balbi, C.; Cavazza, B.; Allera, C.; Lazzarini, G.; Patrone, E.
Fonte: The Biophysical Society Publicador: The Biophysical Society
Tipo: Artigo de Revista Científica
Publicado em /10/1993 EN
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Using differential scanning calorimetry and complementary ultrastructural observations, we have characterized the status of chromatin during the transformation of rat hepatocytes in the resistant hepatocyte model of Solt and Farber (1976. Nature (Lond.). 263:701-703). Differential scanning calorimetry affords a measure of the degree of condensation of chromatin in situ and has therefore been used in this work for the purpose of establishing the nature of the structural changes associated with the emergence of successive cellular populations. Since the resistant hepatocyte model generates a series of synchronous phenotypic changes, it was possible to determine unambiguously the content of heterochromatin at each step of the process. The higher-order structure undergoes a partial relaxation in early developing nodules, isolated 16 weeks after initiation; the thermal transition at 90 degrees C, which is characteristic of noninteracting core particles, increases with respect to control hepatocytes. Dramatic changes occur in persistent (46-week) nodules. The 90 degrees C endotherm dominates the thermogram, while the transition at 107 degrees C, corresponding to the denaturation of the core particle packaged within the heterochromatic domains...

Structural and thermotropic properties of calcium-dimyristoylphosphatidic acid complexes at acidic and neutral pH conditions.

Takahashi, H.; Yasue, T.; Ohki, K.; Hatta, I.
Fonte: The Biophysical Society Publicador: The Biophysical Society
Tipo: Artigo de Revista Científica
Publicado em /10/1995 EN
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Two kinds of calcium-dimyristoylphosphatidic acid (DMPA) complexes at acidic and neutral pH conditions were prepared in the following ways. The complex at pH 4 was obtained by adding Ca2+ to DMPA dispersion in pure water. On the other hand, the complex at pH 7.4 was obtained by adding Ca2+ to DMPA dispersion in the presence of NaOH. The stoichiometries of Ca2+ ion to DMPA molecule are 0.5-0.67 and approximately 1 for the complexes at pH 4 and 7.4, respectively. Static x-ray diffraction shows that the hydrocarbon chains of the Ca(2+)-DMPA complex at pH 4 at 20 degrees C are more tightly packed than those of the complex at pH 7.4 at 20 degrees C. Furthermore, the complex at pH 4 at 20 degrees C gives rise to several reflections that might be related to the ordered arrangement of the Ca2+ ions. These results indicate that the structure of the complex at pH 4 is crystalline-like. In the differential scanning calorimetry (DSC) thermogram, the complex at pH 7.4 undergoes no phase transition in a temperature range between 30 and 80 degrees C. On the other hand, in the DSC thermogram for the complex at pH 4, a peak appears at 65.8 degrees C in the first heating scan. In the successive second heating scan, a transition peak appears at 63.5 degrees C. In connection with the DSC results...

The thermal stability of immunoglobulin: unfolding and aggregation of a multi-domain protein.

Vermeer, A W; Norde, W
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /01/2000 EN
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The denaturation of immunoglobulin G was studied by different calorimetric methods and circular dichroism spectroscopy. The thermogram of the immunoglobulin showed two main transitions that are a superimposition of distinct denaturation steps. It was shown that the two transitions have different sensitivities to changes in temperature and pH. The two peaks represent the F(ab) and F(c) fragments of the IgG molecule. The F(ab) fragment is most sensitive to heat treatment, whereas the F(c) fragment is most sensitive to decreasing pH. The transitions were independent, and the unfolding was immediately followed by an irreversible aggregation step. Below the unfolding temperature, the unfolding is the rate-determining step in the overall denaturation process. At higher temperatures where a relatively high concentration of (partially) unfolded IgG molecules is present, the rate of aggregation is so fast that IgG molecules become locked in aggregates before they are completely denatured. Furthermore, the structure of the aggregates formed depends on the denaturation method. The circular dichroism spectrum of the IgG is also strongly affected by both heat treatment and low pH treatment. It was shown that a strong correlation exists between the denaturation transitions as observed by calorimetry and the changes in secondary structure derived from circular dichroism. After both heat- and low-pH-induced denaturation...

After-exercise thermography for predicting postoperative deep vein thrombosis.

Henderson, H P; Cooke, E D; Bowcock, S A; Hackett, J E
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em 22/04/1978 EN
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After-exercise thermography of the legs was carried out on 50 patients before undergoing major abdominal surgery (group 1) and on 59 patients before elective hip surgery (group 2). The incidence of postoperative deep vein thrombosis (DVT)--diagnosed by the 125I-fibrinogen uptake test in group 1 and phlebography in group 2--was significantly higher in patients whose after-exercise thermogram (AET) had been abnormal. Out of 19 patients in group 1 and 30 in group 2 with a normal AET, two and nine repsectively developed postoperative DVT. Among patients with a unilaterally abnormal AET the incidences were 12 out of 19 patients in group 1 and five out of nine in group 2. The incidences among patients with a bilaterally abnormal AET rose to 11 out of 12 patients in group 1 and 15 out of 20 in group 2. Preoperative after-exercise thermography is a simple, objective test that identifies patients at high risk of developing postoperative thromboembolic disease.

Calorimetry Outside the Box: A New Window into the Plasma Proteome

Garbett, Nichola C.; Miller, James J.; Jenson, Alfred B.; Chaires, Jonathan B.
Fonte: The Biophysical Society Publicador: The Biophysical Society
Tipo: Artigo de Revista Científica
EN
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Differential scanning calorimetry provides a new window into the plasma proteome. Plasma from normal individuals yields a characteristic, reproducible thermogram that appears to represent the weighted sum of denaturation profiles of the most abundant constituent plasma proteins. Plasma from diseased individuals yields dramatically different signature thermograms. Thermograms from individuals suffering from rheumatoid arthritis, systemic lupus, and Lyme disease were measured. Each disease appears to have a distinctive and characteristic thermogram. The difference in thermograms between normal and diseased individuals is not caused by radical changes in the concentrations of the most abundant plasma proteins but rather appears to result from interaction of as yet unknown biomarkers with the major plasma proteins. These results signal a novel use for calorimetry as a diagnostic tool.

Effect of Plasticizer on Release Kinetics of Diclofenac Sodium Pellets Coated with Eudragit RS 30 D

Kibria, Golam; Roni, Monzurul Amin; Absar, Mohammad Shahriarul; Jalil, Reza-ul
Fonte: Springer US Publicador: Springer US
Tipo: Artigo de Revista Científica
Publicado em 20/12/2008 EN
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The present study was designed to investigate the effect of two plasticizers, i.e., triethyl citrate (TEC) and polyethylene glycol 6000 (PEG 6000) on the in vitro release kinetics of diclofenac sodium from sustained-release pellets. Ammonio methacrylate copolymer type B (Eudragit RS 30 D) is used as the release-retarding polymer. Both plasticizers were used at 10% and 15% (w/w) of Eudragit RS 30 D. Pellets were prepared by powder layering technology and coated with Eudragit RS 30 D by air suspension technique. Thermal properties of drug and drug-loaded beads were studied using differential scanning calorimeter (DSC). DSC thermogram represented the identity of raw materials and exhibited no interaction or complexation between the active and excipients used in the pelletization process. Dissolution study was performed by using USP apparatus 1. No significant difference was observed among the physical properties of the coated pellets of different batches. When dissolution was performed as pure drug, about 8.22% and 90% drug was dissolved at 2 h in 0.1 N HCl and at 30 min in buffer (pH 6.8), respectively. From all formulations, the release of drug in acid media was very negligible (maximum 1.8 ± 0.08% at 2 h) but in buffer only 12% and 30% drug was released at 10 h from coated pellets containing TEC and PEG 6000...

Characterization of Monoclonal Gammopathy of Undetermined Significance by Calorimetric Analysis of Blood Serum Proteome

Barceló, Francisca; Cerdà, Joan J.; Gutiérrez, Antonio; Jimenez-Marco, Teresa; Durán, M. Antonia; Novo, Andrés; Ros, Teresa; Sampol, Antonia; Portugal, José
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 20/03/2015 EN
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Monoclonal gammopathy of undetermined significance (MGUS) is a premalignant proliferative disorder that may progress to multiple myeloma, a malignant plasma cell neoplasia. We evaluated differential scanning calorimetry (DSC) as an experimental tool for differentiating serum samples of MGUS patients from healthy individuals. DSC thermograms can be used for monitoring changes in the serum proteome associated with MGUS. MGUS patients showed great variability in serum thermogram characteristics, which depended on the IgG, IgA or IgM isotypes and/or the κ or λ light chains. Thermogram feature parameters distinguished patients with MGUS from healthy people. Serum samples, named as non-MGUS, were also collected from patients with subjacent immunological pathologies who were discarded of having MGUS through serum immunofixation. They were used to verify the sensitivity of DSC for discriminating MGUS from related blood dyscrasias. Only some DSC thermogram feature parameters differentiated, to a lesser extent, between MGUS and non-MGUS individuals. We contemplate DSC as a tool for early diagnosis and monitoring of MGUS.

SSA study of early polyethylenes degradation stages. Effects of attack rate, of average branch length, and of backbone polymethylene sequences length distributions

Pérez, Claudio Javier; Failla, Marcelo Daniel; Carella, Jose Maria
Fonte: Elsevier Publicador: Elsevier
Tipo: info:eu-repo/semantics/article; info:ar-repo/semantics/artículo; info:eu-repo/semantics/publishedVersion Formato: application/pdf
ENG
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Low-density polyethylenes have been attacked by free radicals in the presence of oxygen to promote chains scission, aiming at showing effects of the molecular structure on the thermal behavior as determined by using a Successive Self-Nucleation and Annealing (SSA) technique. Three types of low-density polyethylenes were used: a hydrogenated polybutadiene (HPB), as a model for a statistical linear ethylene–butene copolymer, a linear ethylene–butene copolymer (LLDPE) with short branches not randomly distributed along the main chains, and a low-density polyethylene (LDPE) with randomly placed long and short branching. All the polymers were subjected to thermal oxidation in air. Additionally, the LDPE and HPB were exposed to gamma irradiation in air, while the HPB was also degraded with an organic peroxide. By virtue of the thermally activated oxidation, the three polymers show signs of molecular scission evidenced by the appearance of endotherms in the high temperature range of the final SSA thermogram. These endotherms are associated with the melting of thicker crystals formed by longer polymethylene sequences that were not available for crystallization in the original polymer. Similar indication of chain scission was detected in some of the irradiated HPB. In the case of the irradiated LDPE or the HPB modified with peroxide...

Automated Thermal Face recognition based on Minutiae Extraction

Seal, Ayan; Ganguly, Suranjan; Bhattacharjee, Debotosh; Nasipuri, Mita; Basu, Dipak Kr.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 04/09/2013
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In this paper an efficient approach for human face recognition based on the use of minutiae points in thermal face image is proposed. The thermogram of human face is captured by thermal infra-red camera. Image processing methods are used to pre-process the captured thermogram, from which different physiological features based on blood perfusion data are extracted. Blood perfusion data are related to distribution of blood vessels under the face skin. In the present work, three different methods have been used to get the blood perfusion image, namely bit-plane slicing and medial axis transform, morphological erosion and medial axis transform, sobel edge operators. Distribution of blood vessels is unique for each person and a set of extracted minutiae points from a blood perfusion data of a human face should be unique for that face. Two different methods are discussed for extracting minutiae points from blood perfusion data. For extraction of features entire face image is partitioned into equal size blocks and the total number of minutiae points from each block is computed to construct final feature vector. Therefore, the size of the feature vectors is found to be same as total number of blocks considered. A five layer feed-forward back propagation neural network is used as the classification tool. A number of experiments were conducted to evaluate the performance of the proposed face recognition methodologies with varying block size on the database created at our own laboratory. It has been found that the first method supercedes the other two producing an accuracy of 97.62% with block size 16X16 for bit-plane 4.; Comment: 29 pages...

A comparison study of atmospheric radiometric calibration methods for aerial thermograms

Byrnes, A. E.
Fonte: Rochester Instituto de Tecnologia Publicador: Rochester Instituto de Tecnologia
Tipo: Tese de Doutorado
EN_US
Relevância na Pesquisa
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A comparison study was conducted to evaluate limitations of several atmospheric calibration techniques, including: Angular, Profile, and spectrally corrected and uncorrected LOWTRAN. To accomplish this, a thermal mapper was flown over a shoreline where water surface temperatures were measured coincidentally by a ground crew. The thermogram derived observed radiances were corrected using each of the atmospheric calibration methods so that ground surface temperatures could be predicted. The R.M.S. errors of these ground temperature predictions indicated that all calibration techniques yielded similar results at 1000-foot altitude. The error remained constant for the Profile and LOWTRAN calibration techniques to 6000-foot altitude, but the Angular results singularly indicated a pronounced altitude dependence in ground temperature prediction errors to 6000-foot altitude.