bluuebunny/crossref_metadata_2025_split huggingface dataset:
Analysis of Second and Third Diffracted Orders in Volume Diffraction Gratings Recorded on Photopolymers
Authors: S Gallego  , M Ortuño  , I Pascual  , C Neipp  , A Márquez  , A Beléndez  
Published: September 2005

In this paper the importance of the second and the third diffraction orders in volume holographic gratings recorded on photopolymers is analyzed. The existence of higher harmonics in the refractive index is also evaluated using the Rigorous Coupled Wave Theory (RCW) to fit the curves and to obtain quantitative information of these higher harmonics. Two different types of gratings are analyzed, on the first hand gratings with 35 µm of thickness and 1125 lines/mm are studied and on the second gratings with 70 µm of thickness and 545 lines/mm. Finally, the results obtained for the efficiency of the first diffraction order using Kogelnik's Theory are compared with those obtained using the RCW.
Tm3+-Doped Zn-Diffused LiNbO3 Channel Waveguides
Authors: E Cantelar  , G A Torchia  , J A Sanz-García  , P L Pernas  , G Lifante  , F Cussó  
Published: September 2005

Tm3+-doped LiNbO3 channel waveguides have been fabricated by Zn-diffusion from the vapour phase following a two step procedure. The waveguides have a depth of around 6.5 µm in both polarizations (TM and TE), being multimode at 632.8 nm and single mode at around 2 µm. The spectroscopic properties of the active ions in the waveguides have been explored and compared with that in bulk. The results indicate that Zn-diffusion does not introduce important changes in the optical features of Tm3+ ions, being an adequate technique to produce optical waveguides based on this material.
Photodynamic Effect of Modulated and Continuous LASER Radiation on Cancerous Cells Cultivated In Vitro
Authors: Y Zamora-Juárez  , A J Pérez-Zapata  , L Solano Rodriguez  , E Ramón-Gallegos  , A Cruz-Orea  
Published: September 2005

Photodynamic therapy (PDT) is a cancer therapy that uses nonionizing photons and a photosensitizer to treat solid tumors and surface malignancies. Experiments with cells in vitro have been useful in order to investigate cellular effects due to PDT. In this work, we study the photodynamic effect of modulated and continuous laser radiation on cancerous cells cultivated in vitro. Three experiments were performed for this study. For the first one, HeLa cells were exposed to δ-Aminolevulinic acid (ALA) at concentrations of 0, 10, 20, 40, 80 and 160 µg of ALA/ml of Dulbecco's modified Eagle's medium (DMEM) and were irradiated at total light dose of 80 J/cm2 by using continuous and modulated argon laser light. In the case of modulated radiation, at 1000 Hz, we observed more cellular death (20%) than those produced by continuous light (0%) when these cells were exposed at 20 µg of ALA/ml of DMEM. For other ALA doses cellular deaths were similar in both irradiation types. The death percentage in cancerous cell, after application of PDT with continuous and modulated irradiation, was determined by means of the neutral-red spectrophotometric assay. In the second experiment HeLa cells were exposed only at 20 µg of ALA/ml of DMEM and irradiated with argon laser at total light dose of 80 J/cm2 but using different light modulation frequencies: 100, 160, 600, 1250, 1500, 1850 Hz. Finally in the third experiment, where the HeLa cells were exposed in the same conditions of second experiment, the modulation frequencies used to irradiate the cell were: 10, 20, 40, 80 Hz. It was observed that light modulation frequency at 40 Hz produces maximum cellular death (36%). These results showed that modulated light used in PDT, for low ALA doses in HeLa cells, is more efficient than continuous light irradiation. Modulated irradiation in PDT could reduce the quantity of required ALA, and in consequence to reduce possible collateral damage, for application of this therapy.
Charge Transport Mechanism in Native Deoxyribonucleic Acid
Authors: Z Kutnjak  , C Filipič  , R Podgornik  , L Nordenskiöld  , N Korolev  
Published: September 2005

The frequency dependent electrical conductivity below 1 MHz was studied on wet-spun, macroscopically oriented, calf thymus DNA bulk samples. Temperature dependence of the quasistatic electrical conductivity measured perpendicular to the long DNA axis is discussed within the framework of activated variable range hopping mechanism. It is shown that the frequency dependence of the electrical conductivity in the frequency range of approximately 10-3 Hz–1015 Hz agrees well with predictions of the hole hopping mechanism. Temperature dependence of the electrical conductivity at various frequencies exhibits a crossover at lower temperatures to almost temperature independent mechanism.
Stability of γ-Irradiated Carmine
Authors: Hélio M Cosentino  , Rinaldo S Fontenele  , Nélida L Del Mastro  
Published: September 2005

Carmine is a dye used mainly for coloring food products and galenicals but also in inks. As food irradiation is becoming a regular treatment for food preservation, it is desirable to have a proper knowledge about the radiation sensitivity of additives that can be included in the food formula. The aim of this work was to establish the radiation stability of carmine against Co-60 gamma radiation. Samples of 50% pure carmine powder as well as 50%, 10% and 5% aqueous solutions were irradiated in a Gammacell 220, dose rate of about 5.2 kGy/h, with doses of 0, 1, 2, 4, 8, 16 and 32 kGy. Spectrophotometric readings at 494 nm show a slight decrease of the absorbance as a function of dose: Samples irradiated with 4 and 32 kGy retained 95% and 90% of absorbance of the unirradiated samples respectively. These results indicate a rather good stability of carmine against γ-irradiation.
A Milliprobe for PIXE and PIGE Analysis used for the Study of Colour-Zoned Tourmaline
Authors: R Mateus  , L C Alves  , A P Jesus  , A F Faria  , J P Ribeiro  
Published: September 2005

A “milliprobe” system was implemented by using the focusing properties of a Van de Graaff accelerator, together with a collimator system including 1 mm diameter apertures, to impose the appropriate dimension to the beam spot. The scanning of the sample surface was achieved by X-Y movements of the sample holder (the Z axis being coincident with the beam direction). These movements were accomplished by a motorised X-Y table, with a travel of 25 mm × 25 mm, connected to the sample holder.
This system was used to study specimens of the mineral tourmaline. Two samples, of the “watermelon” zoned tourmaline variety, originating from the Alto Ligonha pegmatite district in northern Mozambique, were analysed by the simultaneous use of PIXE (Proton-Induced X-Ray Emission) and PIGE (Proton-Induced Gamma-Ray Emission) techniques, in order to quantify their composition and try to establish a correlation between the elements (major and trace elements) and colour zoning.
In order to validate the “milliprobe” analysis and study in more detail the frontier between zones of different colours, a microprobe analysis of the samples was also done.
In this work, the mineralogical classification of the samples was accomplished. A correlation was established between the presence of Fe and green colour. It was also concluded that the presence of Mn by itself is not enough to lead to pink colour, which gives support to previous studies that claim that only Mn3+ and not the more common form Mn2+ is responsible for the pink colour.
Transport Barriers and Diffusion Phenomena for the Magnetic Field Lines in Tokamak
Authors: D Constantinescu  , R Constantinescu  
Published: September 2005

The aim of this study is to localize and to describe the transport barriers and the diffusion phenomena that appear in tokamak in two Hamiltonian models for the study of magnetic field line dynamics: a twist map (tokamap) and a non-twist one (rev-tokamap). New results obtained for rev-tokamap will be compared to the already known ones on tokamap and with those concerning the non-twist standard model.
The analysis will be done in terms of a stochasticity parameter describing the perturbation amplitude of the ideal magnetic configuration, and of the q-profiles.
Electronic Properties of Layered Ba0.5Sr0.5TiO3 Heterostructure: Ab initio Hybrid Density Functional Calculations
Authors: S Dorfman  , S Piskunov  , E A Kotomin  , D Fuks  
Published: September 2005

Ab initio calculations of the BST heterostructure with equiatomic constituent of Sr and Ba species has been carried out within hybrid functional B3PW involving a hybrid of non-local Fock exchange and Becke's gradient corrected exchange functional combined with the non-local gradient corrected correlation potential by Perdew and Wang. The suggested scheme of calculations reproduces experimental lattice parameters of both pure BaTiO3 and SrTiO3. The calculated optical band gap for the pure SrTiO3 (BaTiO3) is 3.56 (3.46) eV (expt. 3.25 and 3.20 eV, respectively), i.e. agreement is much better than in the standard LDA or HF calculations. In the Ba0.5Sr0.5TiO3 solid solution the gap is reduced by 0.2 eV. The BST upper valence band consists of O 2p atomic orbitals (AO) with a small admixture of Ti 3d, whereas the conduction band bottom consists mostly of Ti 3d orbitals with a small contribution of O orbitals. The Sr (Ba) atomic orbitals make a significant contribution to the higher part of the conduction band. The electron density maps demonstrate the covalency effects in the Ti-O bonding. The electron density near the Sr atoms is stronger localized, as compared with the Ba ions.
The Role of Selection in the Evolution of Human Mitochondrial Genomes
Authors: Kivisild Toomas , Shen Peidong , Wall Dennis P , Do Bao , Sung Raphael , Davis Karen , Passarino Giuseppe , Underhill Peter A , Scharfe Curt , Torroni Antonio , Scozzari Rosaria , Modiano David , Coppa Alfredo , de Knijff Peter , Feldman Marcus , Cavalli-Sforza Luca L , Oefner Peter J 
Published: September 2005

Abstract
High mutation rate in mammalian mitochondrial DNA generates a highly divergent pool of alleles even within species that have dispersed and expanded in size recently. Phylogenetic analysis of 277 human mitochondrial genomes revealed a significant (P &lt; 0.01) excess of rRNA and nonsynonymous base substitutions among hotspots of recurrent mutation. Most hotspots involved transitions from guanine to adenine that, with thymine-to-cytosine transitions, illustrate the asymmetric bias in codon usage at synonymous sites on the heavy-strand DNA. The mitochondrion-encoded tRNAThr varied significantly more than any other tRNA gene. Threonine and valine codons were involved in 259 of the 414 amino acid replacements observed. The ratio of nonsynonymous changes from and to threonine and valine differed significantly (P = 0.003) between populations with neutral (22/58) and populations with significantly negative Tajima's D values (70/76), independent of their geographic location. In contrast to a recent suggestion that the excess of nonsilent mutations is characteristic of Arctic populations, implying their role in cold adaptation, we demonstrate that the surplus of nonsynonymous mutations is a general feature of the young branches of the phylogenetic tree, affecting also those that are found only in Africa. We introduce a new calibration method of the mutation rate of synonymous transitions to estimate the coalescent times of mtDNA haplogroups.
Modeling Population Genetic Data in Autotetraploid Species
Authors: Luo Z W , Zhang Ze , Zhang R M , Pandey Madhav , Gailing Oliver , Hattemer Hans H , Finkeldey Reiner 
Published: September 2005

Abstract
Allozyme and PCR-based molecular markers have been widely used to investigate genetic diversity and population genetic structure in autotetraploid species. However, an empirical but inaccurate approach was often used to infer marker genotype from the pattern and intensity of gel bands. Obviously, this introduces serious errors in prediction of the marker genotypes and severely biases the data analysis. This article developed a theoretical model to characterize genetic segregation of alleles at genetic marker loci in autotetraploid populations and a novel likelihood-based method to estimate the model parameters. The model properly accounts for segregation complexities due to multiple alleles and double reduction at autotetrasomic loci in natural populations, and the method takes appropriate account of incomplete marker phenotype information with respect to genotype due to multiple-dosage allele segregation at marker loci in tetraploids. The theoretical analyses were validated by making use of a computer simulation study and their utility is demonstrated by analyzing microsatellite marker data collected from two populations of sycamore maple (Acer pseudoplatanus L.), an economically important autotetraploid tree species. Numerical analyses based on simulation data indicate that the model parameters can be adequately estimated and double reduction is detected with good power using reasonable sample size.
Subgingival Microbiota in Peri‐Implant Mucosa Lesions and Adjacent Teeth in Partially Edentulous Patients
Authors: Botero Javier E. , González Ana M. , Mercado Ramiro A. , Olave Gilberto , Contreras Adolfo 
Published: September 2005

Background: Osseointegrated dental implants have been shown to be a predictable approach to provide the adequate support for the replacement of missing teeth. It has been observed that implants showing signs of peri‐implantitis contain subgingival microbiota similar to that around natural teeth with periodontal disease. This study identified the subgingival microbiota around implants with peri‐implant lesions and natural teeth in partially edentulous patients.Methods: Clinical and radiographic parameters were recorded and microbial samples taken from 16 implants with signs of pocketing, 12 neighboring and 11 non‐neighboring teeth to the affected implants in 11 patients and 15 stable implants in eight patients (controls). Samples were cultured using techniques for Enterobacteriaceae spp and facultative/anaerobic periodontal pathogens. Statistical analysis included Friedman test to establish differences between the subgingival microbiota cultured from implants and teeth and two‐tailed Mann Whitney test and chi square to find differences in two separate samples (P ≤0.05).Results: There were statistical differences between the subgingival microbiota in peri‐implant lesions and stable implants for Gram‐negative enteric rods (P <0.05). P. gingivalis (1.42%) was detected in peri‐implant lesions but not in stable implants. A significant correlation between the subgingival microbiota from implants and neighboring teeth for Gram‐negative enteric rods (P = 0.023) and implants and non‐neighboring teeth for P. gingivalis (P = 0.042) was found. The frequency detection of Gram‐negative enteric rods (75%) and P. intermedia/nigrescens (25%) was higher in peri‐implant lesions (P <0.05).Conclusions: The subgingival microbiota in peri‐implant lesions showed high levels of periodontopathic bacteria and superinfecting bacteria compared to healthy stable implants. The role of superinfecting bacteria in the pathogenesis of periimplant lesions needs further investigation. J Periodontol 2005; 76:1490‐1495.
Effects of Chitosan on Human Periodontal Ligament Fibroblasts In Vitro and on Bone Formation in Rat Calvarial Defects
Authors: Pang Eun‐Kyoung , Paik Jeong‐Won , Kim Soo‐Kyoung , Jung Ui‐Won , Kim Chang‐Sung , Cho Kyoo‐Sung , Kim Chong‐Kwan , Choi Seong‐Ho 
Published: September 2005

Background: The purpose of this study was to evaluate the effect of chitosan on human periodontal ligament fibroblasts (hPDLF) in vitro and on bone formation in rat calvarial defects in vivo.Methods: Fibroblast populations were obtained from individuals with a healthy periodontium and cultured in α minimum essential medium (MEM) for the control group. For the experimental groups, cells were cultured in α‐MEM containing chitosan at concentrations of 0.01, 0.1, 1, or 2 mg/ml. The 3‐(4,5‐dimethyl‐thiazole‐2‐yl)‐2,5‐diphenyl tetrazolium bromide (MTT) assay, reverse transcription‐polymerase chain reaction (RT‐PCR) and the assay of alkaline phosphatase (ALPase) activity were performed. Eight mm calvarial critical‐sized defects were created in 30 male Sprague‐Dawley rats. The animals were divided into three groups of 10 animals each. The defects were treated with either chitosan/absorbable collagen sponge (ACS) or ACS alone in the experimental groups or were left untreated (surgical controls). The animals were sacrificed at 2 or 8 weeks post‐surgery and the treatment outcomes were evaluated using histological and histomorphometric parameters.Results: The chitosan‐induced proliferative responses of the hPDLF reached a plateau at a concentration of 0.1 mg/ml (P <0.05). When the hPDLF were stimulated with 0.1 mg/ml chitosan, both the mRNA expression of type I collagen and the ALP activity were significantly up‐regulated (P <0.05). The surgical implantation of chitosan/ACS enhanced the new bone formation at 8 weeks post‐surgery and the amount of new bone formation of the chitosan/ACS group was significantly greater than that of both the ACS alone group and the surgical control group (P <0.01).The new bone area and defect closure in the chitosan/ACS group were significantly greater than those in the ACS control and sham surgery control groups at 8 weeks (P <0.01). However, the chitosan/ ACS group exhibited significantly less bone density than both the ACS control and the sham surgery control group at 8 weeks (P <0.01).Conclusions: Chitosan (0.1 mg/ml) enhanced the type I collagen synthesis and facilitated the differentiation into osteogenic cells. Chitosan reconstituted with ACS has a significant potential to accelerate the regeneration of bone in rat calvarial critical size defects. J Periodontol 2005;76:1526‐1533.
Tetraploid/Diploid Mosaicism With Generalized Aggressive Periodontitis
Authors: Tözüm Tolga F. , Berker Ezel , Akincibay Hakan , Özer Özlem , Aktaş Dilek , Tezcan Ilhan , Şekerci Sükran Ç. , El Hakan , Eratalay Kenan , Tunçbilek Ergül 
Published: September 2005

Background: Changes of chromosome number diploid to triploid or tetraploid states are rare in human pregnancies, where the main clinical features of tetraploidy are delayed growth and/or craniofacial abnormalities. The present report describes the oral features of tetraploid/diploid mosaicism. Although the medical literature described the physical manifestations of this genetic abnormality, the oral features of this disorder were not previously described.Methods: A 13‐year‐old patient presented because of his severe periodontal conditions. Clinical, radiological, microbiologic, immunologic, and genetic examinations were conducted.Results: Long eyelashes and mandibular micrognathia were noticeable in his extraoral examination. Intraoral examination revealed significant generalized edema of the gingiva and severe sulcular bleeding on probing. Generalized maxillary and mandibular alveolar destruction was determined with radiographic examination. Actinobacillus actinomycetemcomitans was also detected in his subgingival samples. He was diagnosed as generalized aggressive periodontitis. His medical cytogenetic examination revealed 92,XXYY (25%)/46,XY (75%) karyotype indicating tetraploid/diploid mosaicism. He was given initial and advanced periodontal therapy and he is currently under a routine follow‐up period.Conclusions: This report provides information on the oral characteristics of tetraploid/diploid mosaicism and describes periodontal treatment. Severe periodontal conditions such as aggressive periodontitis may accompany tetraploid/diploid mosaicism subjects and these patients should be frequently seen by their dental practitioners. It is suggested that initial and/or advanced periodontal procedures may be a way of treating tetraploid/diploid mosaicism subjects with aggressive periodontitis. The importance of physical examination and medical consultation is also discussed. J Periodontol 2005;76:1567‐1571.
A script‐enabled interactive checklist document for efficient management of electronic devices in a busy multimodality radiotherapy clinic
Authors: Pepin Mark D. , Brost Eric E. , Klein Kristi A. , Garces Yolanda I. , Brinkmann Debra H. 
Published: February 2024

PurposeDevelop an efficient, interactive, and instructive checklist document for the management of implanted electronic medical devices in a multimodality radiotherapy clinic.MethodsThe built‐in scripting and interactivity of a popular commercial word processor was used to develop an interactive document that changes the information presented to the user based on drop‐down selections. The interactivity and scripting were compatible with the radiation oncology information system (ROIS) which allows the document to be accessible by all team members and serve as a permanent record in a patient's electronic chart.ResultsThe final interactive document, which was clinically deployed after beta testing with a group consisting of nurses and medical physicists, presents information and action plans to the user based on multiple departmental medical device decision trees that are specific to the combination of device, treatment modality, rhythm‐pacing dependence for cardiac devices, and distance from the device to the treatment volume.ConclusionA script‐enabled interactive document was developed for a busy multimodality clinic, condensing multiple comprehensive departmental guidelines spanning multiple device types and treatment modalities into a single interactive checklist accessible within the ROIS. Given the wide accessibility of the commercial word processor, this approach could be adopted by other clinics to streamline their own respective workflows.
Technical note: Minimizing CIED artifacts on a 0.35 T MRI‐Linac using deep learning
Authors: Curcuru Austen N. , Yang Deshan , An Hongyu , Cuculich Phillip S. , Robinson Clifford G. , Gach H. Michael 
Published: February 2024

AbstractBackgroundArtifacts from implantable cardioverter defibrillators (ICDs) are a challenge to magnetic resonance imaging (MRI)‐guided radiotherapy (MRgRT).PurposeThis study tested an unsupervised generative adversarial network to mitigate ICD artifacts in balanced steady‐state free precession (bSSFP) cine MRIs and improve image quality and tracking performance for MRgRT.MethodsFourteen healthy volunteers (Group A) were scanned on a 0.35 T MRI‐Linac with and without an MR conditional ICD taped to their left pectoral to simulate an implanted ICD. bSSFP MRI data from 12 of the volunteers were used to train a CycleGAN model to reduce ICD artifacts. The data from the remaining two volunteers were used for testing. In addition, the dataset was reorganized three times using a Leave‐One‐Out scheme. Tracking metrics [Dice similarity coefficient (DSC), target registration error (TRE), and 95 percentile Hausdorff distance (95% HD)] were evaluated for whole‐heart contours. Image quality metrics [normalized root mean square error (nRMSE), peak signal‐to‐noise ratio (PSNR), and multiscale structural similarity (MS‐SSIM) scores] were evaluated. The technique was also tested qualitatively on three additional ICD datasets (Group B) including a patient with an implanted ICD.ResultsFor the whole‐heart contour with CycleGAN reconstruction: 1) Mean DSC rose from 0.910 to 0.935; 2) Mean TRE dropped from 4.488 to 2.877 mm; and 3) Mean 95% HD dropped from 10.236 to 7.700 mm. For the whole‐body slice with CycleGAN reconstruction: 1) Mean nRMSE dropped from 0.644 to 0.420; 2) Mean MS‐SSIM rose from 0.779 to 0.819; and 3) Mean PSNR rose from 18.744 to 22.368. The three Group B datasets evaluated qualitatively displayed a reduction in ICD artifacts in the heart.ConclusionCycleGAN‐generated reconstructions significantly improved both tracking and image quality metrics when used to mitigate artifacts from ICDs.