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Phase matching refers to a process in which atom-field interactions lead to the creation of an output field that propagates coherently through the interaction volume. By studying light scattering from arrays of cold atoms, we show that conditions for phase matching change as the dimensionality of the system decreases. In particular, for a single atomic chain, there is phase-matched reflective scattering in a cone about the symmetry axis of the array that scales as the square of the number of atoms in the chain. For two chains of atoms, the phase-matched reflective scattering can be enhanced or diminished as a result of Bragg scattering. Such scattering can be used for mapping collective states within an array of neutral atoms onto propagating light fields and for establishing quantum links between separated arrays.
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Hanbury Brown-Twiss interference and stimulated emission, two fundamental processes in atomic physics, have been studied in a wide range of applications in science and technology. We study interference effects that occur when a weak probe is sent through a gas of two-level atoms that are prepared in a singly excited collective (Dicke or "superatom") state and for atoms prepared in a factorized state. We measure the time-integrated second-order correlation function g^{(2)} of the output field as a function of the delay τ between the input probe field and radiation emitted by the atoms and find that, for the Dicke state, g^{(2)} is twice as large for τ=0 as it is for γ_{e}τâ«1 (γ_{e} is an excited state decay rate), while for the product state, this ratio is equal to 3/2. The results agree with those of a theoretical model in which any effects related to stimulated emission are totally neglected-the coincidence counts measured in our experiment arise from Hanbury Brown-Twiss interference between the input field and the field radiated by the atoms.
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We report on the first observation of γ rays emitted from an sd-shell hypernucleus, _{Λ}^{19}F. The energy spacing between the ground state doublet, 1/2^{+} and 3/2^{+} states, of _{Λ}^{19}F is determined to be 315.5±0.4(stat)_{-0.5}^{+0.6}(syst) keV by measuring the γ-ray energy of the M1(3/2^{+}â1/2^{+}) transition. In addition, three γ-ray peaks are observed and assigned as E2(5/2^{+}â1/2^{+}), E1(1/2^{-}â1/2^{+}), and E1(1/2^{-}â3/2^{+}) transitions. The excitation energies of the 5/2^{+} and 1/2^{-} states are determined to be 895.2±0.3(stat)±0.5(syst) and 1265.6±1.2(stat)_{-0.5}^{+0.7}(syst) keV, respectively. It is found that the ground state doublet spacing is well described by theoretical models based on existing s- and p-shell hypernuclear data.
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The energy spacing between the spin-doublet bound state of _{Λ}^{4}He(1^{+},0^{+}) was determined to be 1406±2±2 keV, by measuring γ rays for the 1^{+}â0^{+} transition with a high efficiency germanium detector array in coincidence with the ^{4}He(K^{-},π^{-})_{Λ}^{4}He reaction at J-PARC. In comparison to the corresponding energy spacing in the mirror hypernucleus _{Λ}^{4}H, the present result clearly indicates the existence of charge symmetry breaking (CSB) in ΛN interaction. By combining the energy spacings with the known ground-state binding energies, it is also found that the CSB effect is large in the 0^{+} ground state but is vanishingly small in the 1^{+} excited state, demonstrating that the ΛN CSB interaction has spin dependence.
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Data related to radioactivity released from the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident on 15 March 2011 gathered by residents of Miharu, Fukushima Prefecture, and by Tohoku University are presented. These data sets consist of (1) the earliest radiation monitoring by a Geiger counter in the town, (2) ratios of radioactivity between (132)Te and (137)Cs for a wide area between Fukushima and Tokyo, (3) radiation measurement of soil samples collected from 18 school grounds, and (4) external radiation exposure of 1400 students using OSL badges. By combining and analysing these various data sets, a curve for the cumulative total external exposure as a function of time, with 16 : 00 h on 15 March 2011 being time zero, is obtained. The average cumulative external dosage is estimated to be 10 mSv (σ = 4.2 mSv) over 10 years. In addition, the initiative that the residents of Miharu took in response to the FDNPP accident, which became known as The Misho Project (MP), is documented; in particular, the time at which the municipality instructed the immediate ingestion of iodine tablets by those under the age of 40, 13 : 00 h on 15 March 2011, is assessed.
Assuntos
Acidente Nuclear de Fukushima , Centrais Nucleares , Radiação Ionizante , Radiometria/estatística & dados numéricos , JapãoRESUMO
BACKGROUND: Chemokines and chemokine receptors not only have significant roles in cancer metastasis and tumorigenesis but also act as antitumour agents. The interaction between the Crk-like adaptor protein (CrkL), which is encoded by the CRKL gene, and non-receptor tyrosine kinase c-ABL is reported to transform many cells into malignant cells. We examined the effects of CC chemokine receptor 7 (CCR7), CCR7 ligands and CrkL and c-ABL in lung adenocarcinoma. METHODS: One hundred and twenty patients with lung adenocarcinoma were included in this historical cohort analysis. We examined CCR7 and CCR7 ligands and CrkL and c-ABL mRNA expressions in surgically resected lung adenocarcinoma specimens and evaluated their contribution to prognosis, and the relationship with epidermal growth factor receptor (EGFR) and TP53 mutations. RESULTS: High CCR7 mRNA expressions indicated better prognoses than those of the groups with low CCR7 mRNA expressions (P=0.007, HR=2.00, 95% CI of ratio: 1.22 -3.31). In lung adenocarcinoma, CrkL and c-ABL mRNAs were related to CCR7 mRNA expression (P<0.0001). CrkL and c-ABL mRNA expressions were influenced by EGFR mutations. A high expression of CCL19 was a good prognostic factor of lung adenocarcinoma. CONCLUSION: We propose that CCR7 and CCL19 are clinically good prognostic factors and that CCR7 is strongly related to CrkL and c-ABL kinase mRNA expression in lung adenocarcinoma.
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Adenocarcinoma/metabolismo , Adenocarcinoma/mortalidade , Biomarcadores Tumorais/metabolismo , Quimiocina CCL19/biossíntese , Neoplasias Pulmonares/metabolismo , Neoplasias Pulmonares/mortalidade , Receptores CCR7/metabolismo , Proteínas Adaptadoras de Transdução de Sinal/genética , Adenocarcinoma/cirurgia , Adenocarcinoma de Pulmão , Adulto , Idoso , Idoso de 80 Anos ou mais , Biomarcadores Tumorais/genética , Quimiocina CCL19/genética , Receptores ErbB/genética , Feminino , Humanos , Neoplasias Pulmonares/cirurgia , Metástase Linfática , Masculino , Pessoa de Meia-Idade , Proteínas Nucleares/genética , Prognóstico , Proteínas Proto-Oncogênicas c-abl/genética , RNA Mensageiro/biossíntese , Receptores CCR7/genética , Taxa de Sobrevida , Proteína Supressora de Tumor p53/genéticaRESUMO
AIMS: To compare the efficacy and safety of these two agents and the impact on surrogate markers related to diabetic complications in Japanese type 2 diabetic patients. METHODS: In a multicenter, open-label trial, 130 patients whose diabetes had been inadequately controlled (HbA1c, 6.9-9.5%) with metformin and/or sulphonylurea were randomly assigned to a sitagliptin group (50 mg/day) or a pioglitazone group (15 mg/day) and were followed up for 24 weeks. At 16 weeks, if the patient's HbA1c level was ≥6.5%, the dose of sitagliptin or pioglitazone was increased up to 100 or 30 mg/day, respectively. Main outcome measure was the difference in the mean changes in the HbA1c level from baseline at 24 weeks between these two groups. RESULTS: Of the 130 patients who were enrolled, 115 subjects (sitagliptin group: 58 patients, pioglitazone group: 57 patients) completed this trial. At 0 weeks, the mean HbA1c level was 7.47 ± 0.66% in the sitagliptin group and 7.40 ± 0.61% in the pioglitazone group. At 24 weeks, the mean changes in the HbA1c level from baseline were -0.86 ± 0.63% versus -0.58 ± 0.68% (p = 0.024). Hypoglycaemia (2 patients, 3.4% vs. 2 patients, 3.5%), gastrointestinal symptoms (3 patients, 5.2% vs. 1 patient, 1.8%) and pretibial oedema (0 patients, 0% vs. 39 patients, 68.4%, p < 0.001) were observed for 24 weeks. CONCLUSIONS: Sitagliptin was not only more tolerable, but also more effective than pioglitazone in Japanese type 2 diabetic patients who had been treated with metformin and/or sulphonylurea.
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Glicemia/efeitos dos fármacos , Diabetes Mellitus Tipo 2/tratamento farmacológico , Hemoglobinas Glicadas/efeitos dos fármacos , Hipoglicemiantes/uso terapêutico , Pirazinas/uso terapêutico , Tiazolidinedionas/uso terapêutico , Triazóis/uso terapêutico , Adulto , Idoso , Povo Asiático/estatística & dados numéricos , Glicemia/metabolismo , Diabetes Mellitus Tipo 2/sangue , Diabetes Mellitus Tipo 2/epidemiologia , Quimioterapia Combinada , Feminino , Hemoglobinas Glicadas/metabolismo , Humanos , Japão/epidemiologia , Masculino , Metformina/uso terapêutico , Pessoa de Meia-Idade , Pioglitazona , Fosfato de Sitagliptina , Compostos de Sulfonilureia/uso terapêutico , Resultado do TratamentoRESUMO
We report on the mapping of quantum-Hall edge states by quasiresonant photovoltage measurements using a near-field scanning optical microscope. We have observed fine structures near sample edges that shift inward with an increase in magnetic field in accordance with the shift of the positions of the quantum-Hall edge states. We have found a transition from the weak disorder regime where compressible-incompressble strips are visible to the strong disorder regime where fluctuations smear out incompressible strips.
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BACKGROUND: Hyperkeratosis and acanthosis occur in inflamed skin. Proliferation and differentiation of keratinocytes are important processes during epidermal repair after inflammation. Neuropsin and its human homologue kallikrein-related peptidase 8 (KLK8) have been reported to be involved in epidermal proliferation and differentiation, but the involved molecular mechanisms are obscure. OBJECTIVES: To explore the molecular mechanism of KLK8/neuropsin-induced hyperkeratosis and acanthosis in inflamed skin. METHODS: The molecular mechanism involved in KLK8/neuropsin-induced hyperkeratosis and acanthosis in inflamed skin was investigated both in vivo and in vitro using neuropsin knockout mice and KLK8 knockdown human keratinocytes. Neuropsin-related genes were identified by differential gene display. The localization and functional relationship of the molecules affected downstream of KLK8/neuropsin in normal and inflamed skin were analysed by in situ hybridization and immunohistochemistry. RESULTS: Hyperkeratosis and acanthosis in sodium lauryl sulphate-stimulated skin were markedly inhibited in neuropsin knockout mice. Knockdown of KLK8/neuropsin increased transcription factor activator protein-2α (AP-2α) expression and decreased keratin 10 expression in human keratinocytes and mouse skin, respectively. AP-2α has been reported to inhibit epidermal proliferation and keratin 10 expression. Distributional analysis showed that KLK8/neuropsin was expressed in the stratum spinosum, AP-2α was expressed in the stratum basale and the lower part of the stratum spinosum, and keratin 10 was expressed throughout the stratum spinosum. CONCLUSIONS: The above findings suggest the following mechanism of events underlying KLK8/neuropsin-induced hyperkeratosis: (i) skin inflammation increases KLK8/neuropsin expression in the stratum spinosum; (ii) the released KLK8/neuropsin inhibits AP-2α expression in the cells of the stratum basale and stratum spinosum; (iii) the decrease in AP-2α results in cell proliferation in the stratum basale and cell differentiation in the stratum spinosum, with an increase in keratin 10 expression.
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Acantose Nigricans/metabolismo , Dermatite/metabolismo , Hiperceratose Epidermolítica/metabolismo , Calicreínas/genética , Queratinócitos/metabolismo , Fator de Transcrição AP-2/antagonistas & inibidores , Acantose Nigricans/etiologia , Acantose Nigricans/genética , Animais , Dermatite/genética , Modelos Animais de Doenças , Humanos , Hiperceratose Epidermolítica/etiologia , Hiperceratose Epidermolítica/genética , Imuno-Histoquímica , Queratina-10/metabolismo , Camundongos , Camundongos Knockout , Reação em Cadeia da Polimerase/métodos , Pele/química , Pele/metabolismo , Dodecilsulfato de Sódio/metabolismo , Fator de Transcrição AP-2/metabolismo , Regulação para CimaRESUMO
Antibiotic resistance of microorganisms is one of the major problems faced in the field of wound care and management resulting in complications like infection and delayed wound healing. Currently a lot of research is focused on developing newer antimicrobials to treat wounds infected with antibiotic resistant microorganisms. Silver has been used as an antimicrobial agent for a long time in the form of metallic silver and silver sulfadiazine ointments. Recently silver nanoparticles have come up as a potent antimicrobial agent and are finding diverse medical applications ranging from silver based dressings to silver coated medical devices. Chitin is a natural biopolymer with properties like biocompatibility and biodegradability. It is widely used as a scaffold for tissue engineering applications. In this work, we developed and characterized novel chitin/nanosilver composite scaffolds for wound healing applications. The antibacterial, blood clotting and cytotoxicity of the prepared composite scaffolds were also studied. These chitin/nanosilver composite scaffolds were found to be bactericidal against S. aureus and E. coli and good blood clotting ability. These results suggested that these chitin/nanosilver composite scaffolds could be used for wound healing applications.
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Bactérias/efeitos dos fármacos , Bandagens , Quitina/química , Nanoestruturas/química , Prata/química , Prata/farmacologia , Alicerces Teciduais , Antibacterianos/química , Antibacterianos/farmacologia , Desenho de Equipamento , Teste de Materiais , Nanoestruturas/administração & dosagem , Cicatrização/efeitos dos fármacosRESUMO
We investigate low-temperature transport characteristics of a side-coupled double quantum dot where only one of the dots is directly connected to the leads. We observe Fano resonances, which arise from interference between discrete levels in one dot and the Kondo effect, or cotunneling in general, in the other dot, playing the role of a continuum. The Kondo resonance is partially suppressed by destructive Fano interference, reflecting novel Fano-Kondo competition. We also present a theoretical calculation based on the tight-binding model with the slave boson mean field approximation, which qualitatively reproduces the experimental findings.
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We have measured the branching ratio of the three-body process in the nonmesonic weak decay of Lambda12C to be 0.29+/-0.13. This result was obtained by reproducing the nucleon and the nucleon pair yields introducing a measured final state interaction. At the same time, we have determined the absolute decay widths, Gamma(n) and Gamma(p), along with Gamma2N, whose relative ratio has been a long-standing puzzle. Including the three-body process, we have successfully reproduced the nucleon energy distribution, the coincidence two-nucleon angular correlation, and the momentum sum distribution simultaneously.
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Beta-chitin is a biopolymer principally found in shells of squid pen. It has the properties of biodegradability, biocompatibility, chemical inertness, wound healing, antibacterial and anti-inflammatory activities. Hydroxyapatite (HAp) is a natural inorganic component of bone and teeth and has osteoconductive property. In this work, beta-chitin-HAp composite membranes were prepared by alternate soaking of beta-chitin membranes in CaCl2 (pH 7.4) and Na2HPO4 solutions for 2 h in each solution. After 1, 3 and 5 cycles of immersion, beta-chitin membranes were characterized using the SEM, FT-IR, EDS and XRD analyses. The results showed the presence of apatite layer on surface of beta-chitin membranes, and the amounts of size and deposition of apatite layers were increased with increasing number of immersion cycles. Human mesenchymal stem cells (hMSCs) were used for evaluation of the biocompatibility of pristine as well as composite membranes for tissue engineering applications. The presence of apatite layers on the surface of beta-chitin membranes increased the cell attachment and spreading suggesting that beta-chitin-HAp composite membranes can be used for tissue engineering applications.
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Quitina/química , Durapatita/química , Membranas Artificiais , Engenharia Tecidual/métodos , Adesão Celular/fisiologia , Teste de Materiais , Células-Tronco Mesenquimais/metabolismo , Microscopia Eletrônica de Varredura , Espectroscopia de Infravermelho com Transformada de Fourier , Difração de Raios XRESUMO
Alginate/phosphorylated chitin (P-chitin) blend films were prepared by mixing of 2% of alginate and P-chitin in water and then cross-linked with 4% CaCl2 solution. The blended films were characterized by FT-IR. Then, the bioactivity of blend films was studied by biomimetic method in simulated body fluid solution (SBF) for 7, 14 and 21 days. After 7, 14 and 21 days and films were characterized by FT-IR and SEM studies. The SEM and FT-IR studies showed that the hydroxyapatite was formed on the surface of the blend films after 7, 14 and 21 days in the SBF solution. These studies confirmed that the alginate/P-chitin blend films are bioactive. Furthermore, the adsorption of Ni2+, Zn2+ and Cu2+ onto alginate/P-chitin blend films has been investigated. The parameters studied include the pH, contact time, and initial metal ion concentrations. The maximum adsorption capacity of alginate/P-chitin blend films for Ni2+, Zn2+ and Cu2+ at pH 5.0 was found to be 5.67, 2.85 and 11.7 mg/g, respectively. These results suggest that alginate/P-chitin blend films-based technologies may be developed for water purification and metal ions separation and enrichment.
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Alginatos/química , Quitina/química , Substâncias Macromoleculares/síntese química , Adsorção , Biomimética , Ácido Glucurônico/química , Ácidos Hexurônicos/química , Cinética , Substâncias Macromoleculares/química , Teste de Materiais , Metais Pesados/química , Microscopia Eletrônica de Varredura , Fosforilação , Espectrofotometria Infravermelho , Espectroscopia de Infravermelho com Transformada de FourierRESUMO
We report a case of uterine angiomyolipoma confirmed with molecular-genetic analysis by fluorescence in situ hybridization (FISH). A 25-year-old nulliparous woman visited Yamaguchi University Hospital with a complaint of lower abdominal pain. Magnetic resonance imaging demonstrated an ill-bordered uterine tumor and exploratory laparotomy revealed a myometrial elastic-soft tumor at the anterior wall of the uterine corpus. Histopathologically, the tumor consisted of fascicles of smooth muscle cells with intermingled adipocytes and small to medium-sized arterial blood vessels surrounded by epithelioid cells of clear cytoplasm. FISH examination revealed chromosome X trisomy, which was comparable to a previously reported molecular-genetic finding of PEComa family tumors including angiomyolipoma. Although the tumor was immunohistochemically negative for HMB-45 antigen, the histological and FISH findings were compatible with angiomyolipoma.
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Antígenos de Neoplasias/análise , Biomarcadores Tumorais/análise , Proteínas de Neoplasias/análise , Neoplasias de Células Epitelioides Perivasculares/diagnóstico , Neoplasias Uterinas/diagnóstico , Adulto , Angiomiolipoma/diagnóstico , Angiomiolipoma/imunologia , Angiomiolipoma/patologia , Cromossomos Humanos X/genética , Análise Citogenética , Feminino , Humanos , Hibridização in Situ Fluorescente , Antígenos Específicos de Melanoma , Neoplasias de Células Epitelioides Perivasculares/imunologia , Neoplasias de Células Epitelioides Perivasculares/patologia , Trissomia , Neoplasias Uterinas/imunologia , Neoplasias Uterinas/patologiaRESUMO
OBJECTIVES: Living donor kidney transplant relieves the disease burden of patients with end-stage renal disease but may shorten donor life expectancy; however, their quality of life (QOL) is preserved. Nevertheless, the magnitude of the net gain of this procedure is unknown. We evaluated the QOL of both donors and recipients concurrently and calculated the net utility gain. METHODS: We recruited 210 subjects who visited the kidney transplantation clinic of a university hospital. Subjects were asked to complete the 5-level EQ-5D-based questionnaire, and patient characteristics were extracted from their medical records. We performed multivariate tobit models analysis to evaluate the QOL change caused by transplant surgery and subsequently ran computational simulations to determine the net utility gains of donors and recipients. We also performed sensitivity analyses. RESULTS: After excluding 16 answers with missing data, we analyzed 203 answers in total. After the transplant surgery, recipients gained 0.07 in utility value while donors lost 0.04. In the net utility analysis, we found that the quality-adjusted life years gained ranged from 7.2 to 7.8 in the most favorable case observed in the combination of middle-aged recipients and elderly donors. Assuming no utility discount, the most favorable combination was that with older donors and younger recipients. CONCLUSIONS: These findings indicated that the QOL improvement in recipients was larger than the loss among donors. When calculating the net utilities, a combination of middle-aged recipients and elderly donors yielded the largest net utility, but this was likely derived from assumption in the discount of QOL.
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Transplante de Rim/métodos , Transplante de Rim/psicologia , Doadores Vivos/psicologia , Qualidade de Vida , Adulto , Idoso , Feminino , Humanos , Falência Renal Crônica/epidemiologia , Falência Renal Crônica/etiologia , Masculino , Pessoa de Meia-Idade , Inquéritos e Questionários , Obtenção de Tecidos e ÓrgãosRESUMO
BACKGROUND: Changes in blood flow impedance of the uterine artery (UA) and uterine radial artery (RA) which is in the lower-extremity of the UA were examined during early pregnancy. METHODS: Blood flow impedance was assessed by transvaginal color-pulsed-Doppler-ultrasonography in 72 women from weeks 4-16 of pregnancy and expressed as a resistance index (RI). RESULTS: RA-RI remained at the late-luteal phase level until the 5th week of pregnancy, decreased until the 7th week, and remained low until the 10th week. UA-RI remained at the late-luteal phase level until the 10th week, and then gradually decreased until the 16th week. In nine women with spontaneous abortion, five out of six women with impaired growth of the gestational sac showed high RA-RI at the 6th week of pregnancy, whereas all three women with loss of fetal heart beat at the 8th week showed normal changes in RA-RI. CONCLUSIONS: Our results show different changes in blood flow impedance between the UA and RA during early pregnancy. A significant decrease of RA-RI after the 5th week may reflect vascular remodeling in the maternal-fetal interface at placentation, whereas a significant decrease of UA-RI after the 10th week may reflect changes of the whole uterine blood flow associated with uterine growth.
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Gravidez , Útero/irrigação sanguínea , Resistência Vascular , Aborto Espontâneo/fisiopatologia , Adulto , Artérias/diagnóstico por imagem , Feminino , Morte Fetal , Humanos , Fase Luteal , Complicações na Gravidez/fisiopatologia , Primeiro Trimestre da Gravidez , Segundo Trimestre da Gravidez , Fluxo Sanguíneo Regional , Ultrassonografia Doppler em Cores , Ultrassonografia Doppler de PulsoRESUMO
BACKGROUND: Much attention has been directed toward identifying early signs of cerebral ischemia on computed tomography (CT) images. Hypoattenuation of ischemic brain parenchyma has been found to be the most frequent early sign. PURPOSE: To evaluate the effect of a previously proposed adaptive smoothing filter for improving detection of parenchymal hypoattenuation of acute ischemic stroke on unenhanced CT images. MATERIAL AND METHODS: Twenty-six patients with parenchymal hypoattenuation and 49 control subjects without hypoattenuation were retrospectively selected in this study. The adaptive partial median filter (APMF) designed for improving detectability of hypoattenuation areas on unenhanced CT images was applied. Seven radiologists, including four certified radiologists and three radiology residents, indicated their confidence level regarding the presence (or absence) of hypoattenuation on CT images, first without and then with the APMF processed images. Their performances without and with the APMF processed images were evaluated by receiver operating characteristic (ROC) analysis. RESULTS: The mean areas under the ROC curves (AUC) for all observers increased from 0.875 to 0.929 (P = 0.002) when the radiologists observed with the APMF processed images. The mean sensitivity in the detection of hypoattenuation significantly improved, from 69% (126 of 182 observations) to 89% (151 of 182 observations), when employing the APMF (P = 0.012). The specificity, however, was unaffected by the APMF (P = 0.41). CONCLUSION: The APMF has the potential to improve the detection of parenchymal hypoattenuation of acute ischemic stroke on unenhanced CT images.
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Isquemia Encefálica/diagnóstico por imagem , Interpretação de Imagem Radiográfica Assistida por Computador/métodos , Acidente Vascular Cerebral/diagnóstico por imagem , Tomografia Computadorizada por Raios X/métodos , Adulto , Idoso , Idoso de 80 Anos ou mais , Algoritmos , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Curva ROC , Sensibilidade e EspecificidadeRESUMO
Chitin is known to be natural polymer and it is non-toxic, biodegradable and biocompatible. The chitin-g-poly(epsilon-caprolactone) (chitin-g-PCL) copolymer was prepared by the ring-opening polymerization of epsilon-caprolactone onto chitin gel in the presence of tin(II) 2-ethylhexanoate catalyst by bulk polymerization method under homogeneous system. The prepared copolymer were characterized by FT-IR, (13)C NMR, thermogravimetric analysis (TGA), differential thermal analysis (DTA), scanning electron microscopy (SEM), solubility and X-ray diffraction (XRD). The degree of substitution of chitin-g-PCL copolymer was found to be 0.48. The TGA analysis showed that chitin-g-PCL was slightly less thermal stability than original chitin. It was due to the grafting of PCL reduced the crystalline structure of chitin. DTA analysis of chitin-g-PCL showed the two exothermic peaks between 300 and 400 degrees C. The first peak at 342 degrees C was due to chitin peak and the second peak was due to PCL. These results suggested that chitin and PCL chains were mixed well at a molecular level. The XRD pattern analysis of chitin-g-PCL showed a weak and broader peak, which demonstrated that the conjugation of PCL with chitin suppressed the crystallization of both chitin and PCL to some extent. The SEM studies showed that the chitin gel seems have a smooth surface morphology, but the chitin-g-PCL showed slightly rough morphology due to the grafting of PCL into chitin. The surface morphology studies also confirmed the grafting reaction.
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Quitina/química , Poliésteres/síntese química , Temperatura , Quitina/ultraestrutura , Géis/química , Espectroscopia de Ressonância Magnética , Microscopia Eletrônica de Varredura , Estrutura Molecular , Poliésteres/química , Solubilidade , Espectroscopia de Infravermelho com Transformada de Fourier , Difração de Raios XRESUMO
Chitosan a natural based polymer is non-toxic, biocompatible and biodegradable. Chemical modification of chitosan to generate new bifunctional materials and finally would bring new properties depending on the nature of the group introduced. In our present study, we prepared phosphorylated chitosan (P-chitosan) by using H(3)PO(4)/P(2)O(5)/Et(3)PO(4)/hexanol method. From our present method, we got high yield and high degree of substitution (DS). The prepared P-chitosan (DS-1.18) was characterized by FT IR, (13)C NMR, (31)P NMR, elemental, XRD, TGA, DTA and SEM studies. After the phosphorylation, the solubility of the polymer was improved. The P-chitosan showed less thermal stability and crystallinity than the chitosan. It was due to the phosphorylation.