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Objective: To study the epidemiological characteristics of tsutsugamushi disease, and to confirm the existence of the disease's epidemic foci in Taizhou. Methods: From 2013 to 2014, Dongxing town hospital and Xingqiao town hospital were selected as specimen collection sites in Jingjiang city. Blood samples (5 ml) were collected from 40 patients with acute tsutsugamushi disease. A total of 59 rodents were captured with cage night method in the survey sites at 5, 7, 9, 10, and 11 months in 2013, from which, the spleen, liver, and kidney specimens were selected. Chigger mites were captured by small blackboard method and from the ears of the captured rodents. A total of 226 small blackboards were laid, 27 mites were captured, and the samples were grounded into suspension. Nested-polymerase chain reaction and cell and tissue culture techniques were used to test the specimen from the probable patients, host animals and chigger mites. Results: Among the 40 acute tsutsugamushi disease blood samples, 29 were found to meet the test requirements, 17 were positive for orientia tsutsugamushi nucleic acid with 59% of the positive rate, and 1 stran orientia tsutsugamushi was isolated. 59 rats were captured and the density of mice was 5.5%. Among them, there were 26 Mus musculus (2.4%), 18 Rattus flavipectus (1.7%) and 15 Smelly shrew (density 1.4%). 1 Smelly shrew was tested positive for orientia tsutsugamushi nucleic acid, and the negative results were found in the other rodent specimens. 27 Chigge mites were collected by small blackboard method and the density of mites was 0.12 for each blackboard, among which 3 larvae and 24 nymphs were found. 33 Chigger mites were collected from the ears of 3 Smelly shrew, and the density of the mite was 11 per mouse. All the captured Chigger mites were identified as Leptotrombidium scutellare and 1 group of specimens of Chigger mites from the external environment were positive for orientia tsutsugamushi nucleic acid. Conclusion: There was a high density of mice in the epidemic area from May to November and the species of the chigger mites were Chigger mites in Taizhou. The nucleic acid of the oriental tsutsugamushi was detected in the patients with acute scrub typhus, rodents and vectors. According to the above-mentioned results, it was considered that the scrub typhus epidemic area of Taizhou city has the natural foci of scrub typhus.
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Reservatórios de Doenças , Vetores de Doenças , Orientia tsutsugamushi/isolamento & purificação , Roedores/parasitologia , Tifo por Ácaros/epidemiologia , Trombiculidae/microbiologia , Animais , Meio Ambiente , Humanos , Camundongos , Reação em Cadeia da Polimerase , Ratos , Tifo por Ácaros/diagnóstico , Tifo por Ácaros/transmissãoRESUMO
A profile preferentially partial occlusion removal method for integral imaging is presented. The profile of the occlusion always contains details with significant texture structure, and regions with significant texture structure often lead to reliable depth estimation. Taking the advantage of the significant texture structure, the profile of occlusion is preferentially dealt with, and then the entire occlusion region is determined via regional spreading according to the accurate profile. The details of occlusion can be accurately removed and the occluded scene is also retained to the maximum degree. In our method, elemental images are integrated into a four-dimensional light field to provide consistently reliable depth estimation and occlusion decisions among all elemental images. Experimental results show that the proposed method is efficient to deal with the details of the occlusion, and it is robust for the occlusions with different kinds of texture structure.
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We report new limits on a spin-independent weakly interacting massive particle (WIMP)-nucleon interaction cross section using 39.5 kg days of data taken with a p-type point-contact germanium detector of 840 g fiducial mass at the Kuo-Sheng Reactor Neutrino Laboratory. Crucial to this study is the understanding of the selection procedures and, in particular, the bulk-surface events differentiation at the sub-keV range. The signal-retaining and background-rejecting efficiencies were measured with calibration gamma sources and a novel n-type point-contact germanium detector. Part of the parameter space in the cross section versus WIMP-mass implied by various experiments is probed and excluded.
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OBJECTIVE: To investigate the effect of recombinant Schistosoma japonicum egg ribonuclease SjCP1412 (rSjCP1412) on proliferation, cell cycle, apoptosis and activation of human hepatic stellate cells LX-2 in vitro, and explore the underlying mechanisms. METHODS: The rSjCP1412 protein was expressed in Escherichia coli BL21 by prokaryotic expression, and the highly purified soluble rSjCP1412 protein was prepared by Ni NTA affinity chromatography and urea gradient refolding dialysis. Yeast RNA was digested using 12.5, 25.0, 50.0 µg rSjCP1412 proteins at 37 °C for 2, 3, 4 h, and the enzymatic products were electrophoresed on 1.5% agarose gel to observe the RNAase activity of rSjCP1412 protein. The proliferation of LX-2 cells stimulated by different doses of rSjCP1412 protein for 48 hours was measured using CCK-8 assay, and the apoptosis of LX-2 cells stimulated by different doses of rSjCP1412 protein for 48 hours was detected using the Annexin V-FITC/PI double staining, while the percentage of LX-2 cells at G0/G1, S and G2/M phases of cell cycle following stimulation with different doses of rSjCP1412 protein for 48 h was detected by DAPI staining. The type I collagen, type III collagen and α-smooth muscle actin (α-SMA) mRNA expression was quantified using quantitative florescent real-time PCR (qPCR) assay and Western blotting at transcriptional and translational levels in LX-2 cells following stimulation with different doses of rSjCP1412 protein for 48 h, while soluble egg antigen (SEA) served a positive control and PBS without rSjCP1412 protein as a normal control in the above experiments. The expression of collagen I, α-SMA and Smad4 protein was determined using Western blotting in LX-2 cells following stimulation with rSjCP1412 protein, transforming growth factor-ß1 (TGF-ß1) alone or in combination, to examine the signaling for the effect of rSjCP1412 protein on LX-2 cells. RESULTS: The rSjCP1412 protein was successfully expressed and the highly purified soluble rSjCP1412 protein was prepared, which had a RNase activity. Compared with the normal group, the survival rates of LX-2 cells significantly decreased post-treatment with 12.5, 25.0, 50.0 µg/mL rSjCP1412 protein and SEA for 48 h (F = 22.417 and 20.448, both P values < 0.05). The apoptotic rates of LX-2 cells significantly increased post-treatment with 12.5, 25.0, 50.0 µg/mL rSjCP1412 protein for 48 h (F = 11.350, P < 0.05), and treatment with 12.5, 25.0, 50.0 µg/mL rSjCP1412 protein for 48 h resulted in arrest of LX-2 cells in G0/G1 phase (F = 20.710, P < 0.05). Treatment with 12.5, 25.0, 50.0 µg/mL rSjCP1412 protein for 48 h caused a significant reduction in relative expression levels of collagen I (F = 11.340, P < 0.05), collagen III (F = 456.600, P < 0.05) and α-SMA mRNA (F = 23.100, P < 0.05) in LX-2 cells, and both rSjCP1412 protein and SEA treatment caused a significant reduction in collagen I (F = 1 302.000, P < 0.05), α-SMA (F = 49.750, P < 0.05) and Smad4 protein expression (F = 52.420, P < 0.05) in LX-2 cells. In addition, rSjCP1412 protein treatment inhibited collagen I (F = 66.290, P < 0.05), α-SMA (F = 31.300, P < 0.05) and Smad4 protein expression (F = 27.010, P < 0.05) in LX-2 cells activated by TGF-ß1. CONCLUSIONS: rSjCP1412 protein may induce apoptosis of LX-2 cells and inhibit proliferation, cell cycle and activation of LX-2 cells through down-regulating Smad4 signaling molecules.
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Schistosoma japonicum , Animais , Humanos , Schistosoma japonicum/metabolismo , Fator de Crescimento Transformador beta1/metabolismo , Proteína Smad4/metabolismo , Cirrose Hepática/tratamento farmacológico , Células Estreladas do Fígado/patologia , Ribonucleases/metabolismo , Ribonucleases/farmacologia , Ribonucleases/uso terapêutico , Linhagem Celular , RNA Mensageiro/metabolismoRESUMO
Commercial 0.5 kW Yb-doped fiber amplifiers have been characterized and found to be suitable for coherent beam combining. Eight such fiber amplifiers have been coherently combined in a tiled-aperture configuration with 78% combining efficiency and total output power of 4 kW. The power-in-the-bucket vertical beam quality of the combined output is 1.25 times diffraction limited at full power. The beam-combining performance is independent of output power.
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Neutrophilic inflammation occurs during asthma exacerbation, and especially, in patients with steroid-refractory asthma, but the underlying mechanisms are poorly understood. Recently, a significant accumulation of neutrophil extracellular traps (NETs) in the airways of neutrophilic asthma has been documented, suggesting that NETs may play an important role in the pathogenesis. In this study, we firstly demonstrated that NETs could induce human airway epithelial cell damage in vitro. In a mouse asthmatic model of neutrophil-dominated airway inflammation, we found that NETs were markedly increased in bronchoalveolar lavage (BAL), and the formation of NETs exacerbated the airway inflammation. Additionally, a small-molecule drug necrostatin-1 (Nec-1) shown to inhibit NETs formation was found to alleviate the neutrophil-dominated airway inflammation. Nec-1 reduced total protein concentration, myeloperoxidase activity, and the levels of inflammatory cytokines in BAL. Finally, further experiments proved that the inhibition of Nec-1 on NETs formation might be related to its ability to inhibiting mixed lineage kinase domain-like (MLKL) phosphorylation and perforation. Together, these results document that NETs are closely associated with the pathogenesis of neutrophilic asthma and inhibition of the formation of NETs by Nec-1 may be a new therapeutic strategy to ameliorate neutrophil-dominated airway inflammation.
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Antiasmáticos/uso terapêutico , Asma/tratamento farmacológico , Imidazóis/uso terapêutico , Indóis/uso terapêutico , Inflamação/tratamento farmacológico , Neutrófilos/imunologia , Proteínas Quinases/metabolismo , Animais , Modelos Animais de Doenças , Armadilhas Extracelulares/metabolismo , Humanos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Ativação de Neutrófilo , FosforilaçãoRESUMO
We studied the distribution of catechol O-methyltransferase (COMT) genotypes in the Chinese Fujian Han population and explored the potential effect of COMT genetic polymorphism on the pharmacokinetics of levodopa. Polymerase chain reaction (PCR) was employed in the COMT genotype analysis of 166 volunteers. After a single oral dose of levodopa/benserazide, the plasma concentration of levodopa was determined by high-performance liquid chromatography (HPLC) with electrochemical detection (ECD). In the 166 subjects, the frequencies of G/G, G/A and A/A COMT genotypes were 58.4%, 36.7% and 4.9%, respectively. The frequency of the homozygous A/A genotype was much lower than in caucasians and Southwest Asians. COMT activity of erythrocytes in the G/A genotype group was significantly lower than in the G/G genotype group but significantly higher than in the A/A genotype group. There was no significant difference in pharmacokinetic parameters, including t(1/2alpha), t(1/2beta), AUC(0-infinity), CL/F, C(max), t(max) and V/F. The frequency of COMT genotypes in the Chinese Fujian Han population, which is related to COMT enzyme activity, is significantly different from that in caucasians and Southwest Asians. The pharmacokinetic characteristics of levodopa in healthy Chinese subjects may not be dependent on their COMT genotype status. From the 166 volunteers, 5 G/G, 5 G/A and 4 A/A genotype male subjects were recruited for the study of levodopa pharmacokinetics.
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Antiparkinsonianos/farmacocinética , Catecol O-Metiltransferase/genética , Levodopa/farmacocinética , Polimorfismo Genético , Adulto , Área Sob a Curva , Povo Asiático/genética , Benserazida/administração & dosagem , China , Cromatografia Líquida de Alta Pressão , Combinação de Medicamentos , Feminino , Genótipo , Meia-Vida , Humanos , Masculino , Reação em Cadeia da Polimerase , População Branca/genética , Adulto JovemRESUMO
OBJECTIVE: To observe the effect of micro ribonucleic acid (miR)-9 on the myocardial fibrosis (MF) in rats and explore its mechanism of action. MATERIALS AND METHODS: A total of 30 rats were selected to prepare the models of MF and randomly divided into Sham group, Model group and MiR-9 group. The rat heart weight (HW)/body weight (BW) and left ventricular weight (LVW)/BW were determined. The content of hydroxyproline (Hyp) in the myocardial tissues of left ventricle was measured using a spectrophotometer. Enzyme-linked immunosorbent assay (ELISA) was performed to determine the levels of type I and type III collagens in myocardial tissues, and the level of miR-9 in myocardial tissues was determined via reverse transcription-polymerase chain reaction (RT-PCR). Finally, Western blotting was conducted to measure the levels of transforming growth factor-ß1 (TGF-ß1) and Smads2 proteins. RESULTS: Compared with Sham group, Model group exhibited increased HW/BW and LVW/BW and markedly raised Hyp content and type I collagen, type III collagen, TGF-ß1 protein and Smads2 protein levels, but significantly declined miR-9 expression levels in rats. In MiR-9 group, the rats had substantially decreased HW/BW, LVW/BW, Hyp content, and type I and type III collagen levels as well as lowered TGF-ß1 protein and Smads2 protein levels. CONCLUSIONS: MiR-9 can alleviate the MF in rats by inhibiting the TGF-ß1/Smads signaling pathway.
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Cardiomiopatias/metabolismo , MicroRNAs/metabolismo , Miocárdio/metabolismo , Transdução de Sinais , Proteína Smad2/metabolismo , Fator de Crescimento Transformador beta1/metabolismo , Animais , Cardiomiopatias/patologia , Modelos Animais de Doenças , Masculino , MicroRNAs/genética , Miocárdio/patologia , Ratos , Ratos Sprague-DawleyRESUMO
OBJECTIVE: To investigate the role of Toll-like receptor-4 (TLR4) in the free fatty acids (FFAs) induced human umbilical vein endothelial cells (HUVECs) inflammation and to explore the underlying mechanisms. MATERIALS AND METHODS: HUVECs and HEK293 cell lines were obtained from Shanghai Type Culture Collection. Cell counting kit-8 (CCK8) and flow cytometry (FCM) were performed to examine the cell viability and apoptosis rate of HUVECs induced by FFAs treatments with or without infection of toll-like receptor-4 interference (TLR4i) adenovirus. Enzyme-linked immunosorbent assay (ELISA) was performed to evaluate the inflammatory cytokines release. Quantitative polymerase chain reaction (qPCR) and Western Blot (WB) were used to test the molecular mechanisms of inflammation. RESULTS: FFAs induced inflammatory responses in HUVECs via modulating the TLR4 receptor complex. TLR4i adenovirus interference increased cell viability and decreased cell apoptosis rate. FFAs treatments significantly increased the expressions of inflammatory cytokines interleukin-6 (IL-6), interleukin-8 (IL-8), C-C motif chemokine ligand 5 (CCL5) and CXC chemokine ligand 10 (CXCL10), while TLR4i adenovirus interference significantly reduced these cytokines levels. TLR4-mediated myeloid differential protein-88 (MyD88) expression activating the nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and inhabiting kappa B kinase-beta (IKK-ß). TLR4i adenovirus interference decreased the expressions of these genes at both mRNA level and protein level. CONCLUSIONS: TLR4 mediates FFAs induced inflammatory responses in HUVECs. TLR4 interference in HUVECs significantly reduces the inflammatory cytokines expression, decreases the cell apoptosis rate and increases cell viability.
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Ácidos Graxos não Esterificados/toxicidade , Células Endoteliais da Veia Umbilical Humana/metabolismo , Mediadores da Inflamação/metabolismo , Receptor 4 Toll-Like/metabolismo , Sobrevivência Celular/efeitos dos fármacos , Sobrevivência Celular/fisiologia , Células HEK293 , Células Endoteliais da Veia Umbilical Humana/efeitos dos fármacos , Humanos , Inflamação/induzido quimicamente , Inflamação/metabolismo , Mediadores da Inflamação/antagonistas & inibidores , Receptor 4 Toll-Like/antagonistas & inibidores , Veias Umbilicais/efeitos dos fármacos , Veias Umbilicais/metabolismoRESUMO
In this article, multiple eigen-systems including linear growth rates and eigen-functions have been discovered for the Rayleigh-Taylor instability (RTI) by numerically solving the Sturm-Liouville eigen-value problem in the case of two-dimensional plane geometry. The system called the first mode has the maximal linear growth rate and is just extensively studied in literature. Higher modes have smaller eigen-values, but possess multi-peak eigen-functions which bring on multiple pairs of vortices in the vorticity field. A general fitting expression for the first four eigen-modes is presented. Direct numerical simulations show that high modes lead to appearances of multi-layered spike-bubble pairs, and lots of secondary spikes and bubbles are also generated due to the interactions between internal spikes and bubbles. The present work has potential applications in many research and engineering areas, e.g., in reducing the RTI growth during capsule implosions in inertial confinement fusion.
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Using direct aperture optimization, we have developed an inverse planning approach that is capable of producing efficient intensity modulated radiotherapy (IMRT) treatment plans that can be delivered without a multileaf collimator. This "jaws-only" approach to IMRT uses a series of rectangular field shapes to achieve a high degree of intensity modulation from each beam direction. Direct aperture optimization is used to directly optimize the jaw positions and the relative weights assigned to each aperture. Because the constraints imposed by the jaws are incorporated into the optimization, the need for leaf sequencing is eliminated. Results are shown for five patient cases covering three treatment sites: pancreas, breast, and prostate. For these cases, between 15 and 20 jaws-only apertures were required per beam direction in order to obtain conformal IMRT treatment plans. Each plan was delivered to a phantom, and absolute and relative dose measurements were recorded. The typical treatment time to deliver these plans was 18 min. The jaws-only approach provides an additional IMRT delivery option for clinics without a multileaf collimator.
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Algoritmos , Modelos Biológicos , Neoplasias/radioterapia , Radiometria/métodos , Planejamento da Radioterapia Assistida por Computador/métodos , Radioterapia Conformacional/métodos , Simulação por Computador , Humanos , Especificidade de Órgãos , Dosagem Radioterapêutica , Eficiência Biológica RelativaRESUMO
Doppler backscattering systems (DBSs) have been widely used in magnetic confinement fusion devices to measure the density fluctuations and propagation velocity of turbulence. However, the received signals of a DBS usually include both zero-order reflection and backscattering components, which results in interference in calculating the Doppler shift frequency from the backscattering components. A novel method is introduced here for estimating the Doppler shift frequency by separating the zero-order reflection and backscattering components using the cross-phase spectrum between the I-signal and Q-signal from a quadrature mixer, based on the difference in symmetrical characteristics between the zero-order reflection and backscattering signal spectra. It is proven that this method is more effective than traditional approaches, such as multiple signal classification and fast Fourier transformation, for extracting Doppler shift information.
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Doppler backscattering system can measure the perpendicular velocity and fluctuation amplitude of the density turbulence with intermediate wavenumber. An eight-channel Doppler backscattering system has been installed in the Experimental Advanced Superconducting Tokamak (EAST), which can probe eight different radial locations simultaneously by launching eight fixed frequencies (55, 57.5, 60, 62.5, 67.5, 70, 72.5, 75 GHz) into plasma. The quasi-optical system consists of circular corrugated waveguide transmission, a fixed parabolic mirror, and a rotatable parabolic mirror which are integrated with quasi-optics front-end of the profile reflectometer inside the vacuum vessel. The incidence angle can be chosen from 5° to 12°, and the wavenumber range is 2-15/cm with the wavenumber resolution Δk/k≤0.21. Ray tracing simulations are used to calculate the scattering locations and the perpendicular wavenumber. The dynamic range of this new eight-channel Doppler backscattering system can be as large as 40 dB in the EAST. In this article, the hardware design, the ray tracing, and the preliminary experimental results in the EAST will be presented.
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Millimeter-wave imaging diagnostics, with large poloidal span and wide radial range, have been developed on the EAST tokamak for visualization of 2D electron temperature and density fluctuations. A 384 channel (24 poloidal × 16 radial) Electron Cyclotron Emission Imaging (ECEI) system in F-band (90-140 GHz) was installed on the EAST tokamak in 2012 to provide 2D electron temperature fluctuation images with high spatial and temporal resolution. A co-located Microwave Imaging Reflectometry (MIR) will be installed for imaging of density fluctuations by December 2016. This "4th generation" MIR system has eight independent frequency illumination beams in W-band (75-110 GHz) driven by fast tuning synthesizers and active multipliers. Both of these advanced millimeter-wave imaging diagnostic systems have applied the latest techniques. A novel design philosophy "general optics structure" has been employed for the design of the ECEI and MIR receiver optics with large aperture. The extended radial and poloidal coverage of ECEI on EAST is made possible by innovations in the design of front-end optics. The front-end optical structures of the two imaging diagnostics, ECEI and MIR, have been integrated into a compact system, including the ECEI receiver and MIR transmitter and receiver. Two imaging systems share the same mid-plane port for simultaneous, co-located 2D fluctuation measurements of electron density and temperature. An intelligent remote-control is utilized in the MIR electronics systems to maintain focusing at the desired radial region even with density variations by remotely tuning the probe frequencies in about 200 µs. A similar intelligent technique has also been applied on the ECEI IF system, with remote configuration of the attenuations for each channel.
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We have examined the degree to which step-and-shoot IMRT treatment plans can be simplified (using a small number of apertures) without sacrificing the dosimetric quality of the plans. A key element of this study was the use of direct aperture optimization (DAO), an inverse planning technique where all of the multi-leaf collimator constraints are incorporated into the optimization. For seven cases (1 phantom, 1 prostate, 3 head-and-neck and 2 lung), DAO was used to perform a series of optimizations where the number of apertures per beam direction varied from 1 to 15. In this work, we attempt to provide general guidelines for how many apertures per beam direction are sufficient for various clinical cases using DAO. Analysis of the optimized treatment plans reveals that for most cases, only modest improvements in the objective function and the corresponding DVHs are seen beyond 5 apertures per beam direction. However, for more complex cases, some dosimetric gain can be achieved by increasing the number of apertures per beam direction beyond 5. Even in these cases, however, only modest improvements are observed beyond 9 apertures per beam direction. In our clinical experience, 38 out of the first 40 patients treated using IMRT plans produced using DAO were treated with 9 or fewer apertures per beam direction. The results indicate that many step-and-shoot IMRT treatment plans delivered today are more complex than necessary and can be simplified without sacrificing plan quality.
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Aceleradores de Partículas/instrumentação , Radioterapia de Intensidade Modulada/instrumentação , Radioterapia de Intensidade Modulada/métodos , Algoritmos , Simulação por Computador , Humanos , Neoplasias Pulmonares/radioterapia , Masculino , Imagens de Fantasmas , Neoplasias da Próstata/radioterapia , Radiometria , Dosagem Radioterapêutica , Planejamento da Radioterapia Assistida por Computador/métodos , Radioterapia Assistida por Computador , Software , Fatores de TempoRESUMO
Thomson scattering (TS) measurements are performed at different locations in a laser-produced aluminum plasma. Variations of the separation, wavelength shift, and asymmetric distribution of the two ion-acoustic waves are investigated from their spectral-time-resolved TS images. Detailed information on the space-time evolution of the plasma parameters is obtained. Electron distribution and variation of the heat flux in the plasma are also obtained for a steep temperature gradient.
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This paper presents the first investigation of the effect of lithium coating on the optics of Doppler backscattering. A liquid lithium limiter has been applied in the Experimental Advanced Superconducting Tokamak (EAST), and a Doppler backscattering has been installed in the EAST. A parabolic mirror and a flat mirror located in the vacuum vessel are polluted by lithium. An identical optical system of the Doppler backscattering is set up in laboratory. The power distributions of the emission beam after the two mirrors with and without lithium coating (cleaned before and after), are measured at three different distances under four incident frequencies. The results demonstrate that the influence of the lithium coating on the power distributions are very slight, and the Doppler backscattering can work normally under the dosage of lithium during the 2014 EAST campaign.
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Intensity-modulated radiotherapy (IMRT) has been considered as a means of providing dose distributions that conform to concave target volumes. For computer-controlled multileaf collimators (MLCs) to be used to modulate x-ray beams, some procedure must be used to determine the sequence of leaf positions used to produce the desired modulation. This article derives and compares four leaf-sequencing algorithms. MLC leaf sequencing can be accomplished by representing the areal intensity modulation of a beam with a series of beam profiles. A velocity-modulation equation for computing the modulation required for a one-dimensional profile, described originally using more extensive algebra, is derived using a graphic approach. The velocity-modulation approach is compared with an equal incremental step-and-shoot approach derived by Bortfeld and Boyer. An areal step-and-shoot technique derived by Xia and Verhey is introduced and compared with the profile-by-profile methods. Finally, an approach is considered using multiple repeated arcs developed by Yu. This wide variety of methods can yield an approach to IMRT that conforms to the engineering constraints imposed by the design of a particular linear accelerator.
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Radioterapia Conformacional/instrumentação , Algoritmos , Engenharia Biomédica/instrumentação , Gráficos por Computador , Desenho de Equipamento , Humanos , Aceleradores de Partículas , Dosagem Radioterapêutica , Planejamento da Radioterapia Assistida por Computador , Radioterapia Conformacional/métodosRESUMO
PURPOSE: The purpose of this work is to develop a prescription preparation system for efficient field shaping using a multileaf collimator that can be used in community settings as well as research institutions. The efficiency advantage of the computer-controlled multileaf collimator, over cerrobend blocks, to shape radiation fields has been shown in conformal treatments, which typically require complete volumetric computerized tomographic data for three-dimensional radiation treatment planning--a utility not readily available to the general community. As a result, most patients today are treated with conventional radiation therapy. Therefore, we believe that it is very important to fully use the same efficiency advantage of multileaf collimator as a block replacement in conventional practice. METHODS AND MATERIAL: The multileaf collimator prescription preparation systems developed by us acquires prescription images from different sources, including film scanner, and radiation treatment planning systems. The multileaf collimator angle and leaf positions are set from the desired field contour defined on the prescription image, by minimizing the area discrepancies. Interactive graphical tools include manual adjustment of collimator angle and leaf positions, and definition of portions of the field edges that require maximal conformation. Data files of the final leaf positions are transferred to the multileaf collimator controller via a dedicated communication link. RESULTS: We have implemented the field prescription preparation system and a network model for integrating the multileaf collimator and other radiotherapy modalities for routine treatments. For routine plan evaluation, isodose contours measured with film in solid water phantom at prescription depth are overlaid on the prescription image. Preliminary study indicates that the efficiency advantage of the MLC over cerrobend blocks in conformal therapy also holds true for conventional treatments. CONCLUSION: Our model of computer-controlled prescription, evaluation, and treatment using multileaf collimators can be effectively implemented in both community settings and research institutions. The resultant increase in treatment efficiency and accuracy is now available for conventional radiotherapy.