bluuebunny/crossref_metadata_2025_split huggingface dataset:
Sensitive volume effects on Monte Carlo calculated ion chamber response in magnetic fields
Authors: Malkov Victor N. , Rogers D. W. O. 
Published: June 2017

PurposeThe development of magnetic resonance‐guided radiation therapy (MRgRT) necessitates accurate Monte Carlo (MC) models of ion chambers for computing ion chamber corrections to compensate for the presence of the magnetic field. This study evaluates the sensitivity of the ion chamber dose response in a magnetic field on the collection volume used in the MC simulation.MethodsThe EGSnrc system's egs_chamber application is used with a recently developed and validated magnetic field transport code. The calculated dose to the sensitive volume of the chamber per unit incident photon fluence, normalized to that at 0 T, is evaluated as a function of magnetic field for the PTW 30013, PTW 31006, PTW 31010, Exradin A12S, and Exradin A1SL chambers. The sensitive region is varied by excluding the volume corresponding to either 0, 0.5, or 1 mm of distance away from the stem. The photon field, magnetic field, and ion chamber are all oriented perpendicular to each other as in the majority of published experimental works.ResultsThe calculations for a Co‐60 source demonstrate that variations from the 0 mm simulations are on the order of several percent with a maximum deviation, occurring at 0.5 T, of 1.75 ± 0.03% and 3.39 ± 0.06% for the 0.5 mm or 1 mm simulations, respectively, for a 0.057 cm3 A1SL chamber. Larger volume chambers showed smaller, but still non‐negligible, variations. Simulations of the A1SL chamber with a 7 MV photon source, corresponding to the Elekta MR‐linac machine, demonstrate that the effect is slightly reduced but still persists with a maximum deviation of 1.97 ± 0.08% for the 1 mm reduction.ConclusionsUsually, the geometric sensitive volume of the ion chamber is used in MC calculation as a substitute for the potentially unknown, smaller, true collection volume (governed by the complex electric field distribution inside the chamber). The calculations in this study demonstrate that even a small variation in simulated volume can lead to fairly large variations in the MC calculated ion chamber response in a magnetic field. This is an important effect that must be addressed to ensure proper calibration of MRgRT machines using MC ion chamber correction factors. This effect may play a role, even where there is no magnetic field, in small‐field dosimetry when volume averaging effect are important.
Modular transmit/receive arrays using very‐high permittivity dielectric resonator antennas
Authors: O'Reilly Thomas P.A. , Ruytenberg Thomas , Webb Andrew G. 
Published: June 2017

PurposeDielectric resonator antenna (DRAs) are compact structures that exhibit low coupling between adjacent elements and therefore can be used as MRI transmit arrays. In this study, we use very high permittivity materials to construct modular flexible transceive arrays of a variable numbers of elements for operation at 7T.MethodsDRAs were constructed using rectangular blocks of ceramic (lead zirconate titanate, εr = 1070) with the transverse electric (TE)01 mode tuned to 298 MHz. Finite‐difference time‐domain simulations were used to determine the B1 and specific absorption rate distributions.
maps were acquired in a phantom to validate the simulations. Performance was compared to an equally sized surface coil. In vivo images were acquired of the wrist (four elements), ankle (seven elements), and calf muscle (16 elements).ResultsCoupling between DRAs spaced 5 mm apart on a phantom was −18.2 dB compared to −9.1 dB for equivalently spaced surface coils. DRAs showed a higher
intensity close to the antenna but a lower penetration depth compared to the surface coil.ConclusionDRAs show very low coupling compared to equally sized surface coils and can be used in transceive arrays without requiring decoupling networks. The penetration depth of the current DRA geometry means they are ideally suited to imaging of extremities. Magn Reson Med 79:1781–1788, 2018. © 2017 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine. This is an open access article under the terms of the Creative Commons Attribution NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.
Multistate Modeling to Analyze Nosocomial Infection Data: An Introduction and Demonstration
Authors: Wolkewitz Martin , von Cube Maja , Schumacher Martin 
Published: June 2017

OBJECTIVEMultistate and competing risks models have become an established and adequate tool with which to quantify determinants and consequences of nosocomial infections. In this tutorial article, we explain and demonstrate the basics of these models to a broader audience of professionals in health care, infection control, and hospital epidemiology.METHODSUsing a publicly available data set from a cohort study of intensive care unit patients, we show how hospital infection data can be displayed and explored graphically and how simple formulas are derived under some simplified assumptions for illustrating the basic ideas behind multistate models. Only a few simply accessible values (event counts and patient days) and a pocket calculator are needed to reveal basic insights into cumulative risk and clinical outcomes of nosocomial infection in terms of mortality and length of stay.RESULTSWe show how to use these values to perform basic multistate analyses in own data or to correct biased estimates in published data, as these values are often reported. We also show relationships between multistate-based hazard ratios and odds ratios, which are derived from the popular logistic regression model.CONCLUSIONSNo sophisticated statistical software is required to apply a basic multistate model and to avoid typical pitfalls such as time-dependent or competing-risks bias.Infect Control Hosp Epidemiol 2017;38:953–959
Surveillance of Endoscopes: Comparison of Different Sampling Techniques
Authors: Cattoir Lien , Vanzieleghem Thomas , Florin Lisa , Helleputte Tania , De Vos Martine , Verhasselt Bruno , Boelens Jerina , Leroux-Roels Isabel 
Published: June 2017

OBJECTIVETo compare different techniques of endoscope sampling to assess residual bacterial contamination.DESIGNDiagnostic study.SETTINGThe endoscopy unit of an 1,100-bed university hospital performing ~13,000 endoscopic procedures annually.METHODSIn total, 4 sampling techniques, combining flushing fluid with or without a commercial endoscope brush, were compared in an endoscope model. Based on these results, sterile physiological saline flushing with or without PULL THRU brush was selected for evaluation on 40 flexible endoscopes by adenosine triphosphate (ATP) measurement and bacterial culture. Acceptance criteria from the French National guideline (<25 colony-forming units [CFU] per endoscope and absence of indicator microorganisms) were used as part of the evaluation.RESULTSOn biofilm-coated PTFE tubes, physiological saline in combination with a PULL THRU brush generated higher mean ATP values (2,579 relative light units [RLU]) compared with saline alone (1,436 RLU; P=.047). In the endoscope samples, culture yield using saline plus the PULL THRU (mean, 43 CFU; range, 1–400 CFU) was significantly higher than that of saline alone (mean, 17 CFU; range, 0–500 CFU; P<.001). In samples obtained using the saline+PULL THRU brush method, ATP values of samples classified as unacceptable were significantly higher than those of samples classified as acceptable (P=.001).CONCLUSIONPhysiological saline flushing combined with PULL THRU brush to sample endoscopes generated higher ATP values and increased the yield of microbial surveillance culture. Consequently, the acceptance rate of endoscopes based on a defined CFU limit was significantly lower when the saline+PULL THRU method was used instead of saline alone.Infect Control Hosp Epidemiol 2017;38:1062–1069
Early Bilingualism Through the Looking Glass: Latino Preschool Children's Language and Self-Regulation Skills
Authors: Melzi Gigliana , Schick Adina R. , Escobar Kelly 
Published: June 2017

ABSTRACTDuring the early years, children's language skills are developing rapidly. For bilingual children, the development of both languages is highly sensitive to environmental input. Thus, capturing bilingualism in the early years poses a great challenge for researchers, especially those interested in examining how bilingualism might relate to other developmental areas, such as self-regulation. Traditionally, child development researchers have operationalized bilingualism as a categorical variable, most often relying on the use of self-reported data. In the present study, we compared various ways of capturing childhood bilingualism and demonstrated how these different measures privileged divergent aspects of children's bilingual experience, as well as how they were differentially related to children's self-regulation skills.
First report on the successful hybridization ofPangasianodon hypophthalmus(Sauvage, 1878) andClarias gariepinus(Burchell, 1822)
Authors: Okomoda V.T. , Koh I.C.C. , Shahreza M.S. 
Published: June 2017

SummaryBreeding and larval performance of novel hybrids from reciprocal crosses of Asian catfishPangasianodon hypophthalmus(Sauvage, 1878) and African catfishClarias gariepinus(Burchell, 1822) were investigated in this study. Spawning was by hormonal injection of brood fish, artificial fertilization, and incubation in triplicate aquarium tanks (0.5 × 0.5 × 0.5 m3) with continuous aeration. Reciprocal crosses (♀C. gariepinus× ♂P. hypophthalmusand ♀P. hypophthalmus× ♂C. gariepinus) had lower hatchability (≤50%) than their pure siblings (≥75%). Fish from all crosses survived until the juvenile stage but survival at 35 days post hatching (dph) was higher for pureC. gariepinussib. ♀C. gariepinus× ♂P. hypophthalmuswas observed to be less resistant to degradation of water quality than the other crosses, however it had higher body weight compared with the other crosses that showed similar performance. Morphological comparison of surviving juvenile at 35 dph, showed that all ♀P. hypophthalmus× ♂C. gariepinusand 13% of the ♀C. gariepinus× ♂P. hypophthalmusexhibited the very same morphology as that of their maternal parent species, while the other portion of the ♀C. gariepinus× ♂P. hypophthalmuscross exhibited morphological traits that were intermediate between those of both parent species. This study been the first successful attempt to hybridize both species and therefore, laid the groundwork for further studies on the aquaculture potentials of the novel hybrids.
Protective effects of ethanol extracts of Artemisia asiatica Nakai ex Pamp. on ageing-induced deterioration in mouse oocyte quality
Authors: Jeon Hyuk-Joon , You Seung Yeop , Kim Dong Hyun , Jeon Hong Bae , Oh Jeong Su 
Published: June 2017

SummaryFollowing ovulation, oocytes undergo a time-dependent deterioration in quality referred to as post-ovulatory ageing. Although various factors influence the post-ovulatory ageing of oocytes, oxidative stress is a key factor involved in deterioration of oocyte quality. Artemisia asiatica Nakai ex Pamp. has been widely used in East Asia as a food ingredient and traditional medicine for the treatment of inflammation, cancer, and microbial infections. Recent studies have shown that A. asiatica exhibits antioxidative effects. In this study, we investigated whether A. asiatica has the potential to attenuate deterioration in oocyte quality during post-ovulatory ageing. Freshly ovulated mouse oocytes were cultured with 0, 50, 100 or 200 μg/ml ethanol extracts of A. asiatica Nakai ex Pamp. After culture for up to 24 h, various ageing-induced oocyte abnormalities, including morphological changes, reactive oxygen species (ROS) accumulation, apoptosis, chromosome and spindle defects, and mitochondrial aggregation were determined. Treatment of oocytes with A. asiatica extracts reduced ageing-induced morphological changes. Moreover, A. asiatica extracts decreased ROS generation and the onset of apoptosis by preventing elevation of the Bax/Bcl-2 expression ratio during post-ovulatory ageing. Furthermore, A. asiatica extracts attenuated the ageing-induced abnormalities including spindle defects, chromosome misalignment and mitochondrial aggregation. Our results demonstrate that A. asiatica can relieve deterioration in oocyte quality and delay the onset of apoptosis during post-ovulatory ageing.
Development and Validation of Non simultaneous Retinal Image Acquisition–Based Retinal Oximeter
Authors: Singh Sumeer , Velu Gunasekaran , Raman Rajiv 
Published: June 2017

AbstractThe purpose of this study was to develop and validate a tool for the measurement of retinal oxygen saturation using a conventional fundus camera–based nonsimultaneous imaging technique. Retinal oximetry setup comprising a conventional Zeiss FF450IR fundus camera, dual wavelength band-pass filters of wavelengths 570 and 600 nm were used. Image analysis was performed using MATLAB R2013b. All the study participants underwent comprehensive eye examination, fundus examination, complete hemogram analysis, and evaluation of systemic hemodynamics. Fundus images were captured by a nonsimultaneous retinal oximetry. A total of 45 subjects were included in the analysis. Median age of the subjects was 21 years ranging from 19 to 34 years. The median retinal arteriolar and venular oxygen saturation was 94.7% and 55.8%. Comparison of retinal oxygen saturation between three visits showed no statistically significant difference for both arteriolar (p = 0.33)and venular oxygen saturation (p = 0.79). Intraclass correlation coefficients for test–retest, short-term, and day-to-day repeatability were 0.84, 0.90, and 0.86 for arteriolar oxygen saturation and 0.92, 0.98, and 0.98 for retinal venular oxygen saturation. Oxygen saturation in retinal arteriolar and venular blood vessels can be measured by nonsimultaneous image acquisition technique using a conventional fundus camera with good repeatability.
Automatic Thalamus Segmentation from Magnetic Resonance Images Using Multiple Atlases Level Set Framework (MALSF)
Authors: Zhang Minghui , Lu Zhentai , Feng Qianjin , Zhang Yu 
Published: June 2017

AbstractIn this paper, we present an original multiple atlases level set framework (MALSF) for automatic, accurate and robust thalamus segmentation in magnetic resonance images (MRI). The contributions of the MALSF method are twofold. First, the main technical contribution is a novel label fusion strategy in the level set framework. Label fusion is achieved by seeking an optimal level set function that minimizes energy functional with three terms: label fusion term, image based term, and regularization term. This strategy integrates shape prior, image information and the regularity of the thalamus. Second, we use propagated labels from multiple registration methods with different parameters to take full advantage of the complementary information of different registration methods. Since different registration methods and different atlases can yield complementary information, multiple registration and multiple atlases can be incorporated into the level set framework to improve the segmentation performance. Experiments have shown that the MALSF method can improve the segmentation accuracy for the thalamus. Compared to ground truth segmentation, the mean Dice metrics of our method are 0.9239 and 0.9200 for left and right thalamus.
Fullerene-Containing Electrically Conducting Electron Beam Resist for Ultrahigh Integration of Nanometer Lateral-Scale Organic Electronic Devices
Authors: Nakajima Anri , Tabei Tetsuo , Yasukawa Tatsuya 
Published: June 2017

AbstractAn outstanding issue with organic devices is the difficulty of simultaneously controlling the lateral size and position of structures at submicron or nanometer scales. In this study, nanocomposite electron beam (EB) organic resists are proved to be excellent candidates for electrically conductive and/or memory component materials for submicron or nanometer lateral-scale organic electronic devices. The memory and the resist patterning characteristics are investigated for a positive electron beam resist of ZEP520a containing [6,6]-phenyl-C61 butyric acid methyl ester (PCBM). Regarding the memory characteristics, good programming and excellent retention characteristics are obtained for electrons. The carrier transfer and retention mechanisms are also investigated. Regarding the resist patterning characteristics, it is found that line patterns (square patterns) of ZEP520a containing PCBM can be made with widths (side lengths) of less than 200 nm by using an extremely simple process with only EB exposures and developments. The distribution of PCBM molecules or their aggregations is also clarified in ZEP520a containing PCBM. The results of this study open the door to the simple fabrication of highly integrated flexible memories and electrical wires as well as of single-electron or quantum devices, including quantum information devices and sensitive biosensors for multiplexed and simultaneous diagnoses.
Genome-wide DNA methylation analysis of the porcine hypothalamus-pituitary-ovary axis
Authors: Yuan Xiao-Long , Zhang Zhe , Li Bin , Gao Ning , Zhang Hao , Sangild Per Torp , Li Jia-Qi 
Published: June 2017

AbstractPrevious studies have suggested that DNA methylation in both CpG and CpH (where H = C, T or A) contexts plays a critical role in biological functions of different tissues. However, the genome-wide DNA methylation patterns of porcine hypothalamus-pituitary-ovary (HPO) tissues remain virtually unexplored. In this study, methylomes of HPO tissues were profiled to investigate their differences and similarities. We found that HPO methylomes displayed tissue-specific methylation patterns in both CpG and CpH contexts. At gene locations, the methylation and density of CpGs was negatively linked at transcription start sites but positively linked at transcription end sites. The densities of CpGs and CpHs at CpG island (CGI) locations were negatively correlated with their methylation. Moreover, the methylation interactions between CGIs and genes showed similar pattern in the CpG context but tissue-specific pattern in the CpH context. CpGs located in CGIs, upstream regions and exons were protected from methylation dynamics, whereas CGI shores, CGI shelves and intergenic regions were more likely to be targets of methylation changes. The methylation dynamics enriching in a tissue-specific manner appeared to maintain and establish the biological functions of HPO tissues. Our analyses provided valuable insights into the tissue-specific methylomes of porcine HPO tissues.
Teaching Transnasal Endoscopy to Graduate Students Without a Hospital or Simulation Laboratory: Pool Noodles and Cadavers
Authors: Berkowitz Shari Salzhauer 
Published: June 2017

Purpose
This study reports on a training opportunity in endoscopy in which speech-language pathology graduate students use inanimate objects and cadavers. Best practices for transnasal endoscopy in vivo require a physician to be nearby, but many graduate programs do not have this access.

Method
Endoscopy was offered as a graduate elective. Students (13 women) initially learned to manipulate the endoscope through the lumen of a swimming pool noodle that was embedded with trinkets. Endoscopic examination of inanimate objects became increasingly complex, followed by endoscopic examination of a cadaver.

Results
Pre- and postexamination measures and qualitative data from the 13 students revealed that students increased in confidence and in interest in this aspect of the field. All students met practical competencies for handling the endoscope, passing the endoscope on a narrow tube, and visualizing objects. Some students had the opportunity to pass the endoscope on a peer and did so successfully.

Conclusion
For programs with a cadaver lab available, this protocol offers an affordable option compared with purchasing a simulator. For those with neither a cadaver lab nor a simulation lab, passing the endoscope on inanimate objects alone is beneficial to student development and learning.
Impedance matching network for ground eliminated open‐ended resonant coil structure in distributed wireless power transmission systems
Authors: Zarifi Telnaz , Moez Kambiz , Mousavi Pedram 
Published: June 2017

This study reports a novel technique utilising a standing‐wave node as a virtual ground to implement an impedance matching network and power level tuning in a ground eliminated (GE) open‐ended resonant coil structure. This technique with GE open‐ended coils can potentially be used in wireless power transmission (WPT) systems, where an unknown metallic, ungrounded, arbitrary environment is used as a signal propagation medium to deliver electric power to several distributed nodes. To satisfy WPT standards the proposed resonant WPT system with the matching network is implemented and tested at 13.56 MHz. A comprehensive study of the GE open‐ended resonant coil structure demonstrates ground‐plane effects and the necessity of an impedance matching network in no‐ground signal situations. The experimental results confirm the theoretical analysis presenting 9% improvements in mismatch efficiency, and 13.1 times in power transmission efficiency at 13.56 MHz when the matching network is deployed.
Metal-free Oxidative Cross-Coupling Reaction of Aromatic Compounds Containing Heteroatoms
Authors: Morimoto Koji , Dohi Toshifumi , Kita Yasuyuki 
Published: June 2017

The biaryl unit containing a heteroatom is a key structure in a large number of natural products and π-conjugated organic systems. The cross-couplings can provide powerful methods for the construction of biaryls and heterobiaryls; thus the development of a new coupling method has been intensively studied by synthetic chemists. Therefore, the oxidative biaryl coupling reaction of arenes containing a heteroatom is a significantly attractive, convenient, and straightforward route to the synthesis of biaryls due to its operational simplicity avoiding the preparation of the corresponding halogenated and metallated arenes. In this report, recent progress in the field of metal-free oxidative cross-coupling reactions of aromatic compounds using hypervalent iodine(III) reagents, is presented.1	Introduction2	Cyanation and Halogenation Reactions of Heteroaromatic Compounds3	Biaryl Coupling Reaction of Heteroaromatic Compounds3.1	Regioselective Coupling Reaction of Thiophenes3.2	Cross-Coupling Reaction of Thiophenes3.3	Coupling Reaction of EDOT and Pyrroles3.4	Cross-Coupling Reaction of Pyrroles4	Cross-Coupling Reaction of Anilines5	Cross-Coupling Reaction of Phenols6	Cross-Coupling Reaction of N-Heteroaromatics with Aryl Radicals from Diaryliodonium(III) Salts7	Conclusion