bluuebunny/crossref_metadata_2025 huggingface dataset:
Technical Note: On the use of cylindrical ionization chambers for electron beam reference dosimetry
Authors: Muir Bryan R. , McEwen Malcolm R.
Published: September 2017

Purpose

To investigate the use of cylindrical chambers for electron beam dosimetry independent of energy by studying the variability of relative ion chamber perturbation corrections, one of the main concerns for electron beam dosimetry with cylindrical chambers.

Methods

Measurements are made with sets of cylindrical and plane‐parallel reference‐class chambers as a function of depth in water in 8 MeV and 18 MeV electron beams. The ratio of chamber readings for similar chambers is normalized in a high‐energy electron beam and can be thought of as relative perturbation corrections. Data are plotted as a function of mean electron energy at depth for a range of depths close to the phantom surface to R80, the depth at which the ionization falls to 80% of its maximum value. Additional, similar measurements are made in a Virtual Water® phantom with cylindrical chambers at the reference depth in a 4 MeV electron beam.

Results

The variability of relative ion chamber perturbation corrections for nominally identical cylindrical Farmer‐type chambers is found to be less than 0.4%, no worse than plane‐parallel chambers with similar specifications.

Conclusions

This work discusses several issues related to the use of plane‐parallel ion chambers and suggests that reference‐class cylindrical chambers may be appropriate for reference dosimetry of all electron beams. This would simplify the reference dosimetry procedure and improve accuracy of beam calibration.
Application of CRAFT (complete reduction to amplitude frequency table) in nonuniformly sampled (NUS) 2D NMR data processing
Authors: Krishnamurthy Krish , Hari Natarajan
Published: September 2017

The recently published CRAFT (complete reduction to amplitude frequency table) technique converts the raw FID data (i.e., time domain data) into a table of frequencies, amplitudes, decay rate constants, and phases. It offers an alternate approach to decimate time‐domain data, with minimal preprocessing step. It has been shown that application of CRAFT technique to process the t1 dimension of the 2D data significantly improved the detectable resolution by its ability to analyze without the use of ubiquitous apodization of extensively zero‐filled data. It was noted earlier that CRAFT did not resolve sinusoids that were not already resolvable in time‐domain (i.e., t1max dependent resolution). We present a combined NUS–IST–CRAFT approach wherein the NUS acquisition technique (sparse sampling technique) increases the intrinsic resolution in time‐domain (by increasing t1max), IST fills the gap in the sparse sampling, and CRAFT processing extracts the information without loss due to any severe apodization. NUS and CRAFT are thus complementary techniques to improve intrinsic and usable resolution. We show that significant improvement can be achieved with this combination over conventional NUS–IST processing. With reasonable sensitivity, the models can be extended to significantly higher t1max to generate an indirect‐DEPT spectrum that rivals the direct observe counterpart.
Accuracy, repeatability, and interplatform reproducibility of T1 quantification methods used for DCE‐MRI: Results from a multicenter phantom study
Authors: Bane Octavia , Hectors Stefanie J. , Wagner Mathilde , Arlinghaus Lori L. , Aryal Madhava P. , Cao Yue , Chenevert Thomas L. , Fennessy Fiona , Huang Wei , Hylton Nola M. , Kalpathy‐Cramer Jayashree , Keenan Kathryn E. , Malyarenko Dariya I. , Mulkern Robert V. , Newitt David C. , Russek Stephen E. , Stupic Karl F. , Tudorica Alina , Wilmes Lisa J. , Yankeelov Thomas E. , Yen Yi‐Fei , Boss Michael A. , Taouli Bachir
Published: September 2017

Purpose

To determine the in vitro accuracy, test‐retest repeatability, and interplatform reproducibility of T1 quantification protocols used for dynamic contrast‐enhanced MRI at 1.5 and 3 T.

Methods

A T1 phantom with 14 samples was imaged at eight centers with a common inversion‐recovery spin‐echo (IR‐SE) protocol and a variable flip angle (VFA) protocol using seven flip angles, as well as site‐specific protocols (VFA with different flip angles, variable repetition time, proton density, and Look‐Locker inversion recovery). Factors influencing the accuracy (deviation from reference NMR T1 measurements) and repeatability were assessed using general linear mixed models. Interplatform reproducibility was assessed using coefficients of variation.

Results

For the common IR‐SE protocol, accuracy (median error across platforms = 1.4–5.5%) was influenced predominantly by T1 sample (P < 10−6), whereas test‐retest repeatability (median error = 0.2–8.3%) was influenced by the scanner (P < 10−6). For the common VFA protocol, accuracy (median error = 5.7–32.2%) was influenced by field strength (P = 0.006), whereas repeatability (median error = 0.7–25.8%) was influenced by the scanner (P < 0.0001). Interplatform reproducibility with the common VFA was lower at 3 T than 1.5 T (P = 0.004), and lower than that of the common IR‐SE protocol (coefficient of variation 1.5T: VFA/IR‐SE = 11.13%/8.21%, P = 0.028; 3 T: VFA/IR‐SE = 22.87%/5.46%, P = 0.001). Among the site‐specific protocols, Look‐Locker inversion recovery and VFA (2–3 flip angles) protocols showed the best accuracy and repeatability (errors < 15%).

Conclusions

The VFA protocols with 2 to 3 flip angles optimized for different applications achieved acceptable balance of extensive spatial coverage, accuracy, and repeatability in T1 quantification (errors < 15%). Further optimization in terms of flip‐angle choice for each tissue application, and the use of B1 correction, are needed to improve the robustness of VFA protocols for T1 mapping. Magn Reson Med 79:2564–2575, 2018. © 2017 International Society for Magnetic Resonance in Medicine.
Simultaneous acquisition of perfusion image and dynamic MR angiography using time‐encoded pseudo‐continuous ASL
Authors: Suzuki Yuriko , Helle Michael , Koken Peter , Van Cauteren Marc , van Osch Matthias J. P.
Published: September 2017

Purpose

Both dynamic magnetic resonance angiography (4D‐MRA) and perfusion imaging can be acquired by using arterial spin labeling (ASL). While 4D‐MRA highlights large vessel pathology, such as stenosis or collateral blood flow patterns, perfusion imaging provides information on the microvascular status. Therefore, a complete picture of the cerebral hemodynamic condition could be obtained by combining the two techniques. Here, we propose a novel technique for simultaneous acquisition of 4D‐MRA and perfusion imaging using time‐encoded pseudo‐continuous arterial spin labeling.

Methods

The time‐encoded pseudo‐continuous arterial spin labeling module consisted of a first subbolus that was optimized for perfusion imaging by using a labeling duration of 1800 ms, whereas the other six subboli of 130 ms were used for encoding the passage of the labeled spins through the arterial system for 4D‐MRA acquisition. After the entire labeling module, a multishot 3D turbo‐field echo‐planar‐imaging readout was executed for the 4D‐MRA acquisition, immediately followed by a single‐shot, multislice echo‐planar‐imaging readout for perfusion imaging. The optimal excitation flip angle for the 3D turbo‐field echo‐planar‐imaging readout was investigated by evaluating the image quality of the 4D‐MRA and perfusion images as well as the accuracy of the estimated cerebral blood flow values.

Results

When using 36 excitation radiofrequency pulses with flip angles of 5 or 7.5°, the saturation effects of the 3D turbo‐field echo‐planar‐imaging readout on the perfusion images were relatively moderate and after correction, there were no statistically significant differences between the obtained cerebral blood flow values and those from traditional time‐encoded pseudo‐continuous arterial spin labeling.

Conclusions

This study demonstrated that simultaneous acquisition of 4D‐MRA and perfusion images can be achieved by using time‐encoded pseudo‐continuous arterial spin labeling. Magn Reson Med 79:2676–2684, 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.
An improved model for prostate diffusion incorporating the results of Monte Carlo simulations of diffusion in the cellular compartment
Authors: Gilani Nima , Malcolm Paul , Johnson Glyn
Published: September 2017

The purpose of this work was to refine a previously published model of prostate diffusion by incorporating improved estimates of cellular diffusivity obtained by Monte Carlo simulation.

Stromal and epithelial cell size and intracellular volume fraction in different grades of cancer were determined from histological images. Diffusion in different mixtures of cells, corresponding to different tumor grades, was simulated and cellular apparent diffusion coefficient and kurtosis values determined. These values were incorporated into the previously published model of prostate diffusion and model predictions compared with values found in the literature.

Stromal cell radius and intracellular volume fraction were 3.74 ± 0.96 μm and 13 ± 3% respectively in normal peripheral zone (PZ), and were similar in all grades of cancer. Epithelial cell radius and intracellular volume fraction were 3.40 ± 0.15 μm and 45 ± 5% respectively in normal PZ, rising to 4.75 ± 0.20 μm and 70 ± 8% in high grade cancer. Cellular apparent diffusion coefficient and kurtosis were 1.02 μm2 ms−1 and 0.58 respectively in normal PZ, and 0.61 μm2 ms−1 and 1.15 in high grade cancer (variation in simulation values are less than 0.1%). Agreement between model predictions and measurements were good, with a mean square error of 0.22 μm2 ms−1.

Incorporation of cellular diffusion coefficient and kurtosis values obtained by Monte Carlo simulation into a model of prostate diffusion gives good agreement with published results.
Metabolic profile of visual cortex in diabetic rats measured with in vivo proton MRS
Authors: Li Shuang , Wang Xinghua , Yang Junjie , Lei Hao , Wang Xuxia , Xiang Yi
Published: September 2017

The purpose of the present study was to characterize the metabolic profile of the visual cortex in streptozotocin‐induced Type 1 diabetic rats by means of in vivo proton MRS. Several metabolite concentration ratios in the visual cortex were calculated. In addition, postmortem histologic analyses for retinal ganglion cell (RGC) loss, optic nerve injury and visual cortex alterations were monitored. The results showed that diabetes induced several changes in visual cortex metabolites, such as reduced N‐acetylaspartate, glutamate, γ‐aminobutyric acid, taurine and choline‐containing compound levels. Nevertheless, myo‐inositol levels increased significantly as compared with controls. Remarkable RGC loss and optic nerve degeneration were observed by morphological analysis. Moreover, the results showed significant neuronal loss and glial activation in the visual cortex. These findings indicated that, besides vascular abnormalities, neuronal loss and degeneration in the visual pathway were induced due to disrupted glucose homeostasis in diabetes. Metabolic or functional abnormalities were induced in cerebral neurons of the visual cortex by diabetes.
1H–MRS processing parameters affect metabolite quantification: The urgent need for uniform and transparent standardization
Authors: Bhogal Alex A. , Schür Remmelt R. , Houtepen Lotte C. , van de Bank Bart , Boer Vincent O. , Marsman Anouk , Barker Peter B. , Scheenen Tom W.J. , Wijnen Jannie P. , Vinkers Christiaan H. , Klomp Dennis W.J.
Published: September 2017

Proton magnetic resonance spectroscopy (1H–MRS) can be used to quantify in vivo metabolite levels, such as lactate, γ‐aminobutyric acid (GABA) and glutamate (Glu). However, there are considerable analysis choices which can alter the accuracy or precision of 1H–MRS metabolite quantification. It is currently unknown to what extent variations in the analysis pipeline used to quantify 1H–MRS data affect outcomes. The purpose of this study was to evaluate whether the quantification of identical 1H–MRS scans across independent and experienced research groups would yield comparable results. We investigated the influence of model parameters and spectral quantification software on fitted metabolite concentration values. Sixty spectra in 30 individuals (repeated measures) were acquired using a 7‐T MRI scanner. Data were processed by four independent research groups with the freedom to choose their own individualized and optimal parameter settings using LCModel software. Data were processed a second time in one group using an independent software package (NMRWizard) for an additional comparison with a different post‐processing platform. Correlations across research groups of the ratio between the highest and, arguably, the most relevant resonances for neurotransmission [N‐acetyl aspartate (NAA), N‐acetyl aspartyl glutamate (NAAG) and Glu] over the total creatine [creatine (Cr) + phosphocreatine (PCr)] concentration, using Pearson's product–moment correlation coefficient (r), were calculated. Mean inter‐group correlations using LCModel software were 0.87, 0.88 and 0.77 for NAA/Cr + PCr, NAA + NAAG/Cr + PCr and Glu/Cr + PCr, respectively. The mean correlations when comparing NMRWizard results with LCModel fitting results at University Medical Center Utrecht (UMCU) were 0.87, 0.89 and 0.71 for NAA/Cr + PCr, NAA + NAAG/Cr + PCr and Glu/Cr + PCr, respectively. Metabolite quantification using identical 1H–MRS data was influenced by processing parameters, basis sets and software choice. Locally preferred processing choices affected metabolite quantification, even when using identical software. Our results reinforce the notion that standard practices should be established to regularize outcomes of 1H–MRS studies, and that basis sets used for processing should be made available to the scientific community.
Secure and efficient verification for data aggregation in wireless sensor networks
Authors: Merad Boudia Omar Rafik , Senouci Sidi Mohammed , Feham Mohammed
Published: September 2017

The Internet of Things (IoT) concept is, and will be, one of the most interesting topics in the field of Information and Communications Technology. Covering a wide range of applications, wireless sensor networks (WSNs) can play an important role in IoT by seamless integration among thousands of sensors. The benefits of using WSN in IoT include the integrity, scalability, robustness, and easiness in deployment. In WSNs, data aggregation is a famous technique, which, on one hand, plays an essential role in energy preservation and, on the other hand, makes the network prone to different kinds of attacks. The detection of false data injection and impersonation attacks is one of the major concerns in WSNs. In order to verify the data, there is either the end‐to‐end approach or the hop‐by‐hop approach. In the former, the detection of these attacks can only be performed at sink node, i.e., after reception of aggregate, a detection that is inefficient and leads to a significant loss of legitimate data. In this paper, we propose a scheme that provides the end‐to‐end privacy and allows early detection of the attack through a hop‐by‐hop verification, thus reducing the need to rely entirely on sink node for verification. Based on an enhanced version of TinyECC, the solution is implemented on MicaZ and TelosB motes. Through simulation and experimental results, we show the applicability of the scheme for WSNs.
Network design with probabilistic capacities
Authors: Atamtürk Alper , Bhardwaj Avinash
Published: September 2017

We consider a network design problem with random arc capacities and give a formulation with a probabilistic capacity constraint on each cut of the network. To handle the exponentially‐many probabilistic constraints a separation procedure that solves a nonlinear minimum cut problem is introduced. For the case with independent arc capacities, we exploit the supermodularity of the set function defining the constraints and generate cutting planes based on the supermodular covering knapsack polytope. For the general correlated case, we give a reformulation of the constraints that allows to uncover and utilize the submodularity of a related function. The computational results indicate that exploiting the underlying submodularity and supermodularity arising with the probabilistic constraints provides significant advantages over the classical approaches. © 2017 Wiley Periodicals, Inc. NETWORKS, Vol. 71(1), 16–30 2018
Polyurethanes with separately tunable biodegradation behavior and mechanical properties for tissue engineering
Authors: Moghanizadeh‐Ashkezari Mojgan , Shokrollahi Parvin , Zandi Mojgan , Shokrolahi Fatemeh
Published: September 2017

Two series (random and block) poly(glycolide‐co‐ε‐caprolactone) macrodiols with various glycolide to ε‐caprolactone ratios (50/50 and 30/70, R‐PG50C, R‐PG30C, B‐PG50C, and B‐PG30C) were synthesized. Next, segmented polyurethanes (PUs) were synthesized based on the synthesized macrodiols, 1,6‐hexamethylene diisocyanate and 1,4‐butanediol (PU‐R30, PU‐R50, PU‐B30, and PU‐B50). Effect of glycolide (G) and ε‐caprolactone (C) monomers arrangement (random or block) on the PUs properties were investigated via FTIR, 1H NMR, DSC, TGA, DMA, SEM, and mechanical tests. All PUs illustrated Tg (−33°C to −48°C) and Tm (102°C to 139°C) corresponding to the soft and the hard segments, respectively. Polymers based on block macrodiols also showed Tm related to the soft segments. While PUs underwent a two‐step thermal degradation, the PUs based on block macrodiols indicated higher degradation temperature. Dynamic mechanical analysis results evidenced development of a well‐defined microphase separated structure in PU‐R30. Contact angle (about 70°‐80°) and water uptake (around 20% after 24 hours) of the PU films are close to those suitable for tissue engineering materials. The PU based on R‐PG30C (PU‐R30) exhibited the highest tensile strength (2.87 MPa) followed by PU‐B50 and PU‐R50. Over a 63‐day in vitro degradation study in phosphate buffered saline, the PUs showed variable weight loss (up to 40%) depending on their soft segments composition and arrangement. Also, the PUs showed no cytotoxicity. Thus, these PUs with tunable biodegradation rate and mechanical properties are suitable candidates for tissue engineering.
Differing Responses to School Finance Reform: The Haves Versus the Have‐Nots
Authors: Ullrich Laura D.
Published: September 2017

This article analyzes the changes in equity associated with Tennessee's switch to the Basic Education Program during the 1992–1993 school year and the factors that may have impacted changes in equity. Results indicate that the relationship between wealth and state spending has grown over time. Additionally, the relationship between locally provided funding and wealth became more positive over time and led to a considerable gap between education spending in rich and poor districts. In order to decrease this gap in spending, tighter controls are needed on locally provided spending via the school finance system.
Poverty in Europe: Sociodemographics, Portfolios, and Consumption of Wealth‐Poor Households
Authors: Müller Philip
Published: September 2017

In this article, I describe the portfolio structure of poor households within the euro area (EA) using microdata from the Household Finance and Consumption Survey (HFCS), the Luxembourg Wealth Study (LWS), and the Luxembourg Income Study (LIS). My approach differs from existing ones in that I analyze the (net) wealth‐poor instead of the income‐poor households. I am able to identify households in the bottom net wealth decile and study their portfolio structure. From a methodological point of view, my study shows that a poverty indicator based on households’ net wealth needs to be designed and interpreted with great care. Given that wealth accumulates over time and (high‐ income) households can borrow against their future income stream, it is not clear whether low net wealth holdings are really indicative of being poor, for example, in the sense of material deprivation or consumption opportunities. As consumption can be financed from wealth and income, an indicator combining wealth and income may be a solution. I find significant heterogeneity in the portfolios of households in the bottom net wealth decile across countries. The characteristics of the group of households with low wealth are different across countries as well. Real assets are held by fewer less wealthy households than financial assets, and almost all wealth‐poor households own deposits and sight accounts, but only a few have mortgage debt. Wealth‐poor households are, on average, smaller than other households, and their heads are younger. Additionally, less wealthy households are not the unemployed households with low education levels. In some countries, highly educated household heads and full‐time employees belong to the wealth‐poor. The poor households spend, on average, about 20 percent of their gross income on food.
Non‐Equilibrium Phase Behavior of Confined Molecular Films at Low Shear Rates
Authors: Maćkowiak Szymon , Heyes David M. , Pieprzyk Slawomir , Dini Daniele , Brańka Arkadiusz C.
Published: September 2017

In a recent publication [Maćkowiak et al., J. Chem. Phys. 145, 164704 (2016)] the results of Non‐Equilibrium Molecular Dynamics (NEMD) simulations of confined sheared Lennard‐Jones molecular films have been presented. The present work builds on that study by focusing on the low wall speed (shear rate) regime. Maps are given of the steady‐state structures and corresponding friction coefficients in the region where a transition from static to kinetic friction is observed. The boundary between static and kinetic friction regions is determined as a function of wall speed and applied pressure, which is located for wall speeds up to about 0.8 m s−1. It was found that stick‐slip behavior extends to pressures as high as 1000 MPa. The NEMD equations of motion are shown to be consistent with the Prandtl–Tomlinson model in the ‘soft spring’ limit, which leads to a new expression for the friction coefficient. This study provides new details and insights into the nature of anomalous friction behavior in the so‐called Plug‐Slip part of the nonquilibrium phase diagram regime.
Cardioprotective Effects of Pomegranate (Punica granatum) Juice in Patients with Ischemic Heart Disease
Authors: Razani Zahra , Dastani Mostafa , Kazerani Hamid Reza
Published: September 2017

Ischemic heart disease is the leading cause of mortality worldwide. The purpose of this study was to evaluate the cardioprotective effects of pomegranate juice in patients with ischemic heart disease. One hundred patients, diagnosed with unstable angina or myocardial infarction, were randomly assigned to the test and the control groups (n = 50, each). During 5 days of hospitalization, in addition to the conventional medical therapies, the test groups received 220 mL pomegranate juice, daily. During the hospitalization period, the blood pressure, heart rate, as well as the intensity, occurrence, and duration of the angina were evaluated on a regular basis. At the end of the hospitalization period, the serum levels of malondialdehyde, interleukin‐6, and tumor necrosis factor alpha were measured in all patients. The levels of serum troponin and high‐sensitive C‐reactive protein levels were also assayed in patients diagnosed with myocardial infarction. Pomegranate juice caused significant reductions in the intensity, occurrence, and duration of angina pectoris in patients with unstable angina. Consistently, the test patients had significantly lower levels of serum troponin and malondialdehyde. Other studied parameters did not change significantly. The results of this study suggest protective effects of pomegranate juice against myocardial ischemia and reperfusion injury. Copyright © 2017 John Wiley & Sons, Ltd.
Hyphenation of proton transfer reaction mass spectrometry with thermal analysis for monitoring the thermal degradation of retinyl acetate
Authors: Peinado Irene , Mason Marco , Biasioli Franco , Scampicchio Matteo
Published: September 2017

Rationale

The processing of retinyl acetate, a vitamin and biomarker, at high temperatures causes significant decomposition of the compound and thus loss of its activity. The rate of mass loss can be conveniently studied by thermogravimetry (TG). However, this technique generally fails to reveal which compounds have evolved from the compound. In this work we propose a new hyphenation approach to continuously monitor the thermal decomposition of retinyl acetate and follow the evolution of specific volatile organic compounds (VOCs).

Methods

Thermal degradation of retinyl acetate was followed by TG coupled to a direct injection mass spectrometer based on proton transfer reaction mass spectrometry (PTR‐MS) to follow continuously the thermal decomposition of retinyl acetate. The results were also compared with those obtained by a second evolved gas analysis system based on the coupling of TG with FTIR.

Results

The TG results showed two main mass losses, at 180°C and 350°C. When the PTR‐MS instrument was connected to the outlet of the TG instrument, specific fragment ions (m/z 43, 61, 75, 85 and 97) showed characteristic evolution profiles. The first mass loss was mainly associated with the release of acetic acid (m/z 43 and 61), whereas the second mass loss was connected with the degradation of the molecule backbone (m/z 43, 61, 75, 85 and 97). These results were substantially correlated with those achieved by TG coupled with FTIR, although PTR‐MS showed superior performance in terms of the qualitative identification of specific fragments and better sensitivity toward complex organic VOCs.

Conclusions

The proposed TG‐PTR‐MS technique shows a great potential for following in real time the thermal degradation of ingredients such as retinyl acetate and identifying compounds evolved at specific temperatures.
High‐performance liquid chromatography/high‐resolution mass spectrometry for the characterization of transformation products of ionic liquids
Authors: Fabbri Debora , Calza Paola , Noè Giorgio , Santoro Valentina , Medana Claudio
Published: September 2017

Rationale

Ionic liquids (ILs) are a subject of active research in the field of alternative solvents. We studied the behaviour of a piperidine IL, 1‐butyl‐1‐methylpiperidinium tetrafluoroborate (BMPA), through the elucidation of its transformation products (TPs) in water.

Methods

The transformation pathways of BMPA were investigated using high‐performance liquid chromatography (HPLC) combined with a hybrid LTQ‐Orbitrap instrument on the basis of mass defect filtering. TPs of BMPA were identified by fragmentation patterns and accurate mass measurements.

Results

The separation and identification of 32 TPs was achieved. BMPA can be oxidized at different positions in the alkyl chains. The ultimate products corresponds to N‐methyl‐piperidinium and some byproducts involving ring‐opening. Tests of acute toxicity, evaluated with Vibrio Fischeri bacteria, show that BMPA transformation proceeds through the formation of slightly harmful compounds.

Conclusions

Results showed that the main transformation pathways of BMPA were alkyl chain hydroxylation/shortening and de‐alkylation, and that HPLC/LTQ‐Orbitrap can serve as an important analytical platform to gather the unknown TPs of ILs.
Context‐aided analysis of community evolution in networks
Authors: Pallotta Giuliana , Konjevod Goran , Cadena Jose , Nguyen Phan
Published: September 2017

We are interested in detecting and analyzing global changes in dynamic networks (networks that evolve with time). More precisely, we consider changes in the activity distribution within the network, in terms of density (ie, edge existence) and intensity (ie, edge weight). Detecting change in local properties, as well as individual measurements or metrics, has been well studied and often reduces to traditional statistical process control. In contrast, detecting change in larger scale structure of the network is more challenging and not as well understood. We address this problem by proposing a framework for detecting change in network structure based on separate pieces: a probabilistic model for partitioning nodes by their behavior, a label‐unswitching heuristic, and an approach to change detection for sequences of complex objects. We examine the performance of one instantiation of such a framework using mostly previously available pieces. The dataset we use for these investigations is the publicly available New York City Taxi and Limousine Commission dataset covering all taxi trips in New York City since 2009. Using it, we investigate the evolution of an ensemble of networks under different spatiotemporal resolutions. We identify the community structure by fitting a weighted stochastic block model. We offer insights on different node ranking and clustering methods, their ability to capture the rhythm of life in the Big Apple, and their potential usefulness in highlighting changes in the underlying network structure.
A ToF‐SIMS investigation on correlation between grinding environments and sphalerite surface chemistry: implications for mineral selectivity in flotation
Authors: Xia Liuyin , Hart Brian , Chen Zhe , Furlotte Mark , Gingras Gary , Laflamme Patrick
Published: September 2017

Changes in mineral surface properties during grinding play a key role in flotation performance. Time of flight secondary mass spectrometry (ToF‐SIMS) surface chemical analytical studies have shown that flotation separation of sphalerite from chalcopyrite is significantly affected by the oxidation of metal species on the surface of sphalerite. The intensity of iron oxyhydroxyl species on the surface of sphalerite has a positive correlation with poor recovery of sphalerite. Given the link between the presence of oxide species on the surface of sphalerite and a lower recovery during copper flotation, a laboratory study was initiated to evaluate the potential for sphalerite surface oxidation control and improving recovery through grinding. For the investigation, a ball mill that allowed for monitoring pulp chemistry during grinding was utilized to study the impact of grinding conditions on selective flotation of sphalerite. ToF‐SIMS was used to identify and measure the variability in sphalerite surface species as a result of the different test parameters. Variable mill parameters include two types of grinding media, aeration conditions, addition of FeSO4, and altering the pyrite content in the feed ore. ToF‐SIMS analyses of mill discharge samples identified higher intensities of iron oxyhydroxyl species on sphalerite surface subsequent to grinding with mild steel balls, in condition of aeration, use of FeSO4, and by increasing the pyrite content of the feed ore. The higher adsorption of iron oxyhydroxyl species on the surface of sphalerite should be consistent with the lower recovery. To verify this, bench‐scale flotation tests in the presence and absence of FeSO4 were performed; results correlated iron oxyhydroxyl species with the poor sphalerite recovery. Copyright © 2017 John Wiley & Sons, Ltd.
Practical recommendations for reportingFine‐Gray model analyses for competing risk data
Authors: Austin Peter C. , Fine Jason P.
Published: September 2017

In survival analysis, a competing risk is an event whose occurrence precludes the occurrence of the primary event of interest. Outcomes in medical research are frequently subject to competing risks. In survival analysis, there are 2 key questions that can be addressed using competing risk regression models: first, which covariates affect the rate at which events occur, and second, which covariates affect the probability of an event occurring over time. The cause‐specific hazard model estimates the effect of covariates on the rate at which events occur in subjects who are currently event‐free. Subdistribution hazard ratios obtained from the Fine‐Gray model describe the relative effect of covariates on the subdistribution hazard function. Hence, the covariates in this model can also be interpreted as having an effect on the cumulative incidence function or on the probability of events occurring over time. We conducted a review of the use and interpretation of the Fine‐Gray subdistribution hazard model in articles published in the medical literature in 2015. We found that many authors provided an unclear or incorrect interpretation of the regression coefficients associated with this model. An incorrect and inconsistent interpretation of regression coefficients may lead to confusion when comparing results across different studies. Furthermore, an incorrect interpretation of estimated regression coefficients can result in an incorrect understanding about the magnitude of the association between exposure and the incidence of the outcome. The objective of this article is to clarify how these regression coefficients should be reported and to propose suggestions for interpreting these coefficients.
Visible Light Driven Coupling of 2‐aminopyridines and α‐Keto Vinyl Azides for the Synthesis of Imidazo[1, 2‐a]pyridines and Their Cytotoxicity
Authors: Adiyala Praveen Reddy , Sastry Kasinathuni Naga Visweswara , Kovvuri Jeshma , Nagarajan Apoorva , Reddy Velma Ganga , Sayeed Ibrahim Bin , Nayak Vedinthe Lakshma , Maurya Ram Awatar , Kamal Ahmed
Published: September 2017

α‐Keto vinyl azides and 2‐aminopyridines were coupled to yield 1‐aryl‐N‐(2‐arylimidazo[1, 2‐a]pyridin‐3‐yl)methanimines in the presence of visible light using Ru(bpy)3Cl2.6H2O as a photocatalyst. This synthetic protocol allows the formation of 3 new C−N bonds in the overall transformation at ambient temperature. It is applicable to a wide range of vinyl azides and 2‐aminopyridines providing a straightforward access to a variety of highly functionalized imidazo[1, 2‐a]pyridines in high yields. The synthesized imidazo[1, 2‐a]pyridines were evaluated for their cytotoxic activity against a set of four selected human cancer cell lines i.e, A549 (lung cancer), DU‐145 (prostate cancer), MCF‐7 (breast cancer) and Hela (cervical cancer). Many compounds of the series (4 e, 4 g, 4 i, 4 j and 4 u) exhibited promising cytotoxicity in these cancer cell lines.
Dangers on the road: A longitudinal examination of passenger‐initiated violence against bus drivers
Authors: Zhou Biru , Boyer Richard , Guay Stéphane
Published: September 2017

This study examined the impact of workplace violence against 109 bus drivers over a 1‐year span. Workplace violence is related to both psychological and work‐related consequences. Our findings showed that bus drivers experienced a wide range of violence at work and the psychological consequences were devastating: Half of the participants met the diagnostic criteria for acute stress disorder within the first month following the index event. Majority of them experienced at least moderate levels of post‐traumatic stress disorder (PTSD) problems over the 1‐year span. About 9.3% of participants showed a delayed onset of PTSD 6 months after. Furthermore, counter‐supportive behaviours and reexposure to violence played important roles in the maintenance of PTSD symptoms over time. Even though PTSD symptoms per se did not relate to bus driver's confidence in coping with aggressive passengers, the immediate post‐traumatic reaction—symptoms of acute stress disorder—showed a significant long‐term negative effect on bus drivers' confidence in dealing with aggressive passengers 12 months after. This study provided empirical evidence of the changing nature of PTSD symptoms over time among bus drivers.
Transcranial colour‐coded duplex of the intracranial large arteries
Authors: McKiernan Sharmaine , Selmes Christine
Published: September 2017

Transcranial colour‐coded duplex (TCCD) is a non‐invasive ultrasound technique that assesses blood flow within the large arteries of the circle of Willis. In the clinical sonography world, it can be considered a relatively recent technique that is useful to assess cerebral haemodynamics in a variety of conditions. This article covers the anatomy of the circle of Willis, TCCD scanning and information on some common pathologies TCCD may be used to assess. It is important the sonographer is aware of TCCD imaging and of the intricacies involved in the technique.
Effect of the Stirring Mode on the Behavior of Al2O3–MgO Particles and Clusters during Ladle Treatment of Ni‐based Alloy 825
Authors: Kellner Hans E. O. , Karasev Andrey V. , Sundqvist Olle , Jönsson Pär G.
Published: September 2017

It is well known that inclusions affect the properties of alloys. Therefore, the importance of understanding what inclusions exist and how they behave cannot be overstated. This study has examined the behavior of Al2O3–MgO particles and clusters in the melt during the ladle treatment of Alloy 825, who is a Ni‐based Alloy. The effect of different stirring directions of electromagnetic stirring in combination with gas stirring is discussed based on three‐dimensional investigations of the clustered particles. More specifically, the composition, size, and number of particles and clusters are determined after electrolytic extraction of metal samples by using SEM in combination with EDS. The results show that the agglomeration of Al2O3–MgO particles in the melt is faster for an upward induction stirring combined with a gas stirring in comparison to a downward stirring combined with a gas stirring. However, the total removal of clusters from the melt is more effective when using a downward induction stirring compared to when using an upward induction stirring, especially for large size clusters (>11.2 μm). The effect of the different stirring modes on the behavior of the Al2O3–MgO particles and clusters in the melt for the ladle treatment experiments agree with the theoretical predictions based on Stokes’, Brownian, and Turbulent collisions.
Bone Marrow Stem Cells Do Not Contribute to Endometrial Cell Lineages in Chimeric Mouse Models
Authors: Ong Yih Rue , Cousins Fiona L. , Yang Xiaoqing , Mushafi Ahmed Aedh A. Al , Breault David T. , Gargett Caroline E. , Deane James A.
Published: September 2017

Studies from five independent laboratories conclude that bone marrow stem cells transdifferentiate into endometrial stroma, epithelium, and endothelium. We investigated the nature of bone marrow-derived cells in the mouse endometrium by reconstituting irradiated wild type recipients with bone marrow containing transgenic mTert-green fluorescent protein (GFP) or chicken β-actin (Ch β-actin)-GFP reporters. mTert-GFP is a telomerase marker identifying hematopoietic stem cells and subpopulations of epithelial, endothelial, and immune cells in the endometrium. Ch β-actin-GFP is a ubiquitous reporter previously used to identify bone marrow-derived cells in the endometrium. Confocal fluorescence microscopy for GFP and markers of endometrial and immune cells were used to characterize bone marrow-derived cells in the endometrium of transplant recipients. No evidence of GFP+ bone marrow-derived stroma, epithelium, or endothelium was observed in the endometrium of mTert-GFP or Ch β-actin-GFP recipients. All GFP+ cells detected in the endometrium were immune cells expressing the pan leukocyte marker CD45, including CD3+ T cells and F4/80+ macrophages. Further examination of the Ch β-actin-GFP transplant model revealed that bone marrow-derived F4/80+ macrophages immunostained weakly for CD45. These macrophages were abundant in the stroma, infiltrated the epithelial and vascular compartments, and could easily be mistaken for bone marrow-derived endometrial cells. We conclude that it is unlikely that bone marrow cells are able to transdifferentiate into endometrial stroma, epithelium, and endothelium. This result has important therapeutic implications, as the expectation that bone marrow stem cells contribute directly to endometrial regeneration is shaping strategies designed to regenerate endometrium in Asherman's syndrome and to control aberrant endometrial growth in endometriosis.
Cyclic response of a precast composite hollow reinforced concrete column using longitudinal rebars and base plate
Authors: Cha Kyung‐Ryul , Seo Jihye , Kim Seungjun , Kang Young‐Jong , Won Deokhee
Published: September 2017

In this research, the precast segmental construction of composite hollow reinforced concrete (RC) columns was studied. The precast segmental construction of composite hollow RC column requires guidelines for the connections between the bent cap and column segment, connections between column segmental joints, and connections between column segment and footing. The connection methods for different precast composite hollow RC piers were experimentally studied for rational resistance against shear force and bending moments. Two types of precast composite hollow RC columns and cast‐in‐place column were studied in this paper. The performance of these columns was evaluated through experiments. The precast column erected with a base‐plate connection exhibited a performance similar to the cast‐in‐place column.
Study of dielectric properties of luffa–polylactide quadratic splint composites: The effect of cyclic absorption and desorption of water
Authors: Kakar Akshay , Jayamani Elammaran , Soon Kok Heng , Bakri Muhammad Khusairy Bin
Published: September 2017

This study reports on the effects of cyclic hot and cold water absorption on the dielectric properties of luffa–polylactide composites and their potential application as a quadratic mallet finger splint. The study was conducted for dry samples varying in fiber volume percentage from 0% to 20% with increments of 5%. The 15 vol% luffa–polylactide composites were subjected to the cyclic hot and cold water absorption. The changes in the dielectric constant, dissipation factor, and loss factor were measured in the 100 Hz to 1 MHz range. It was found that the higher the number of water cycles, lower the dielectric constant, dissipation factor, and loss factor. Cyclic hot water absorption showed a more significant effect on the dielectric properties than the cyclic cold water absorption. J. VINYL ADDIT. TECHNOL., 24:388–394, 2018. © 2017 Society of Plastics Engineers
Individual pitch control for 2‐bladed wind turbines via multiblade multilag transformation
Authors: Riboldi C. E. D. , Cacciola S.
Published: September 2017

Two‐bladed wind turbines have regained the attention of the community thanks to the advantages in manufacturing cost provided by the lower number of blades and the ease of implementation of effective passive systems for load reduction (ie, teetering pin). Considering both teetering and nonteetering architectures, the dynamics of 2‐bladed turbines is different from that of 3‐bladed machines especially in terms of how multiples of the rotor frequencies in blade signals are translated on the fixed system. Such characteristics have hampered the adoption of active control laws for load mitigation based on individual pitch control, extensively studied for 3‐bladed turbines. A basic element for control development allowing to capture the essence of the relationship between signals on the blades and the fixed system on 2‐bladed turbines–represented by the Coleman transformation for 3‐bladed turbines–has not been identified yet. The present paper tries to fill the gap, presenting an extended transformation–called multiblade multilag–applicable to turbines with an arbitrary number of blades, providing a systematic way to link rotor signals to fixed system signals, thus allowing the application of control algorithms for individual pitch control developed for 3‐bladed turbines to the 2‐bladed case. The paper addresses the problem first at a theoretical level, and subsequently providing applicative results from simulations on virtual models of teetering and nonteetering 2‐bladed turbines. The proposed transformation algorithm and control laws allow to effectively reduce some relevant loads and motions respectively in the nonteetering and teetering scenarios, through a cyclic pitch input.
Uses for expanded production of natural gas liquids: chemicals or power?
Authors: Allen David T. , Cardoso‐Saldaña Felipe J. , McGaughey Gary , McDonald‐Buller Elena , Webster Mort
Published: September 2017

Expanded production of natural gas liquids (NGLs, ethane, propane, butanes) in the United States may continue to be utilized in domestic and international chemical manufacturing; however, this would require the development of expanded transport infrastructures. Electricity generation is an alternative use for NGLs. As a case study of the value of NGLs in electricity generation, the potential use of NGLs in the Texas electrical grid was evaluated. It was assumed that electricity would be generated in 25‐MW gas turbines, located at gas‐processing plants where NGLs in produced gas are separated to create pipeline‐quality gas. The potential magnitude of NGL‐based power generation in the Texas grid, using NGLs produced in the Eagle Ford and Barnett oil and gas production regions in Texas, was estimated to be up to 2.7 GW of electricity, 6% of average demand on the grid. The NGL‐based electricity generation displaced coal and natural gas‐based generation, with little impact on the use of renewables. At the assumed efficiency (34.7%) and nonfuel operating cost ($7/MWh) of small gas turbines, NGLs are only fully utilized for electricity generation in the Texas grid when fuel prices are lower than $1.50 per million BTU (a discount of $0.90 per million BTU relative to the fuel price of coal assumed in the modeling). Higher prices might be supported if NGLs are used for electricity generation at times of high demand or if larger, higher efficiency turbines are utilized. WIREs Energy Environ 2018, 7:e258. doi: 10.1002/wene.258

This article is categorized under:

Fossil Fuels > Systems and Infrastructure

Energy Infrastructure > Systems and Infrastructure
Study of gamma/X‐ray interaction in Kondo insulators
Authors: Manjunatha H.C. , Seenappa L. , Sridhar K.N. , ChikkaHanumantharayappa
Published: September 2017

We have studied the gamma/X‐ray interaction parameters such as mass attenuation coefficient, mean free path (λ), half value layer, 10th value layer, energy‐absorption buildup factors, and variation of electrical conductivity with the energy of gamma/X‐ray between 1 keV and 100 GeV for Kondo insulators such as FeSi, Ce3Bi4Pt3, SmB6, YbB12, CeNiSn, CeRhSb, CeRuSn, and CeFeP. The variation of photon interaction parameters with incident energy of gamma/X‐ray is graphically represented. We have also identified the X‐ray absorption edges for the Kondo insulators. This identified X‐ray absorption edges are useful in the characterizing of Kondo insulators such as FeSi, Ce3Bi4Pt3, SmB6, YbB12, CeNiSn, CeRhSb, CeRuSn, and CeFeP. Hence, these data are also useful in the material science. This type of data for Kondo insulators is not available in literature. Hence, this work is first of its kind, and it is useful in various fields of nuclear physics.
The Inquiries: A Lion’s Den
Authors: Hilton Claire
Published: September 2017

The Sans Everything inquiries (August 1967–February 1968) were disturbing. A sense of open mindedness to evaluate the allegations was minimal, and the Ministry expected conclusions to indicate that practices were satisfactory. This chapter explores three hospital inquiries in depth—Friern, St Lawrence’s and Storthes Hall—corresponding with availability of archive sources. The inquiry chairmen lacked experience of public sector administration, including of the way statutory authorities could cover up deficiencies. They discredited witnesses based on their personalities and status within the hospitals, rather than evaluating the evidence they gave. They made errors when judging standards, due to their stereotypical expectations and lack of knowledge about good clinical practice. The Council on Tribunals, the public body monitoring inquiries, criticised the procedures. Cabinet Minister Richard Crossman described the inquiries as ‘fairly well rigged’.