bluuebunny/crossref_metadata_2025 huggingface dataset:
Design of a broadband microwave absorber from wideband receiving antenna array
Authors: Chang Yumei , Che Wenquan , Chow Yung L.
Published: August 2018

In some extent, microwave absorbers and receiving antennas have some similarities, for both of them aim at receiving the ambient electromagnetic wave around. The essential difference between them is that the receiving antenna must transmit the EM wave to the loading system, but the microwave absorber just need to dissipate them. In this work, we studied a novel broadband microwave absorber, which is achieved from a wideband folded‐dipole antenna array backed through a quarter‐wavelength spacer by a metal ground. By studying the impedance locus of the folded dipole array on Smith chart, the authors first obtained a wideband folded‐dipole array antenna, and then changed it to an absorber by replacing the excitations with lump resistors. Both simulation and measurement results show that the folded‐dipole array‐based microwave absorber can achieve a wide bandwidth of 100% at the normal incident waves as in mode of antenna array, while the center frequency is at 5.5 GHz. Meanwhile, the −10 dB bandwidth of the absorber can still be over 90% at an oblique incident waves of 30°.
W band single diode fundamental mixer with high intermediate frequency
Authors: Guo Jian , Qian Cheng , Xu Jie , Chen Zhenhua
Published: August 2018

The design approach of a W‐band single diode fundamental mixer is presented here. This mixer features planar structure easy for integrating and high intermediate frequency (IF). The mixer consists of a diplexer formed by a hammer‐head lowpass filter and a coupled line with open stubs, a broadband bandpass filter (BPF) using short stubs, a series diode, and the matching networks. This mixer covers IF signal up to 18 GHz by optimizing the frequency response of the diplexer, the radio frequency (RF) BPF, and the matching networks. Two open stubs are attached to both ends of the RF BPF, in order to add a transmission zero at local oscillator (LO) frequency. By this way, the required out‐of‐band rejection is fulfilled with lower order BPF, thus reducing the in‐band insertion loss. In addition, the coupled line with open stubs has low insertion loss at LO frequency, while having a transmission zero at RF frequency. All of the techniques above lead to a low loss high IF mixer. The measured conversion loss is 6.7–10 dB with 8–19 GHz IF and 82 GHz LO.
Beam steering antenna with reconfigurable parasitic elements for FPV drone applications
Authors: Kim Sungpeel , Choi Jaehoon
Published: August 2018

A beam steering antenna for first person view (FPV) drone communication applications is proposed. The proposed antenna consists of a driven monopole antenna at the center of an equilateral triangle structure with reconfigurable parasitic elements. All parasitic elements are composed of a metallic strip with a PIN diode loaded in the middle of each strip. Depending on the on/off state of each diode, the parasitic element can act as an opaque or transparent surface to a vertically polarized incident wave. Therefore, beam steering properties of the proposed antenna can be achieved by changing the states of the PIN diodes. The measured results were in good agreement with the simulated results and demonstrated that the proposed antenna could be used for 5.8 GHz ISM band FPV applications.
Miniaturization of logarithmic spiral antenna with modified Koch curve
Authors: Sharma Chetna , Vishwakarma Dinesh
Published: August 2018

This study proposes a unique methodology of reducing the footprint of logarithmic spiral antenna with the help of suitably scaled fractal known as modified Koch curve. In this process, first, the outer contour of the spiral arm is approximated with Fibonacci spiral which discretizes the former's geometry with a certain number of quarter circular sections. These sections are then superimposed with the iterations of modified Koch curve that leads to the miniaturization of the test antenna by 46% without compromising its spectral and radiation properties. The generalized mathematical approach has been developed to enable designing a compact logarithmic spiral antenna with an arbitrary growth factor. Finally, to validate the accuracy of proposed procedure, the prototypes having a selected growth rate have been fabricated and measured. The results such as reflection coefficient, impedance, gain, efficiency, radiation pattern, and axial ratio bandwidth of the first and second iterated modified Koch logarithmic spiral antenna are similar to the original logarithmic spiral operating in frequency range 2.00–18.30 GHz.
SOA‐based AOWC of 128QAM using Gaussian pulse shaping for transmission system with 227 Gbps
Authors: Li Guang , Li Jianqing , Chen Guojie , Huang Xuguang
Published: August 2018

We demonstrate an ultra‐high‐speed transmission system‐based, all‐optical wavelength conversion using Gaussian pulse shaping and 128 quadrature amplitude modulation. In this system, the modulated ultra‐high‐speed, photonic‐carrier signals with the modulation format of 128 quadrature amplitude modulation are coupled with the outputs of the double pump lasers, and amplified by nonlinear, all‐optical processing via a semiconductor optical amplifier. The transmission system with the wavelength conversion from 193.4 to 193.19 THz is then achieved. By the compensation of transmission impairments based on the digital signal processing algorithms, the single‐carrier signals with the converted wavelength of 193.19 THz are transmitted over the standard single‐mode fiber with the bit rate of 227 Gbps. In addition, the transmission performances influenced by the optical signal‐to‐noise ratio, injection current of the semiconductor optical amplifier, and the bandwidth of the Gaussian optical filter are analyzed. The relationship curves about bit error rate and error vector magnitude under different conditions are given, and the relationship between bit error rate and error vector magnitude is demonstrated.
A directional circularly polarized crossed‐dipole antenna with bandwidth enhancement
Authors: Guo Zifang , Zhao Zhiqin , Yang Yaohui , Ding Xiaoxiang
Published: August 2018

A broadband circularly polarized antenna based on the crossed‐dipole structure is designed. The antenna consists of a pair of dual‐side printed crossed dipoles, a loop phase delay line, and a parasitic patch. By modifying the configuration of the dipoles and introducing a parasitic patch, a wide axial ratio (AR) bandwidth is obtained. A defected ground plane is designed, which has a significant improvement in extending the 3‐dB AR bandwidth and enhances the gain. The proposed prototype is manufactured and measured for validation. Measured results show that the antenna achieves both −10 dB impedance bandwidth and 3‐dB AR bandwidth of 68.6% (2.3–4.7 GHz). Moreover, the average gain of the antenna is about 8 dBi within the operating band, with a floating less than 2 dB.
Ku‐band gap waveguide filter design with improved out of band response
Authors: Mazinani Masood , Arezoomand Masoud , Pirhadi Abbas
Published: August 2018

In this paper, a Ku‐band filter was designed based on the Gap Waveguide (GW) technology with improved out‐of‐band response. After extracting an appropriate circuit model for the intended filter, different parts of it such as the resonators, couplers between resonators as well as input and output couplers to resonators were implemented using the GW structures. After the filter was designed in the operating frequency band, its out‐of‐band behavior, which occurs due to the excitation of higher modes, was examined and the characteristics of the filter were improved in out‐of‐operating frequency band. Finally, the filter was fabricated and a comparison of the simulation results with the measurement results confirmed the validity of the designed method.
High‐frequency dielectric analysis of carbon nanofibers from pan precursor at different pyrolysis temperatures
Authors: Munajat N. A. , Nurfaizey A. H. , Bahar A. A. M. , You K. Y. , Fadzullah S. H. S. M. , Omar G.
Published: August 2018

Carbon nanofibers (CNF) produced from pyrolysis of electrospun polyacrylonitrile (PAN) precursor has received a great amount of attention due to their promising potentials. However, there are limited studies on the electrical properties of the CNF, especially at high‐frequency range. In this study, CNF from PAN precursor were produced by electrospinning technique. Characterizations of the nanofibers were carried out in terms of physical, dielectric, and chemical properties. The stabilization of nanofibers took place at 240°C whilst carbonization process took place at temperatures of 800°C, 1000°C, and 1200°C, respectively. In terms of physical properties, the color of the nanofiber webs changed from white to brown and black, after stabilization and carbonization process accompanied by significant reduction in average fiber diameter. Dielectric analysis of the nanofibers was obtained by measuring the wave propagation characteristics at frequency range of 1 GHz to 10 GHz. Higher dielectric constants of the material were observed for fibers processed at higher carbonization temperatures. Good conductivity was also observed with loss tangent value that is higher than 1. The results were correlated with FTIR transmittance results, indicating greater amount of carbon are present in the nanofiber material. From the findings, the unique behavior of the nanofibers makes it practically potential for sensor applications. Explorations of future research in this area are to be sought.
A comprehensive model for phase noise characteristics of an optoelectronic oscillator
Authors: Guo Jiao Jiao , Jin Xiang Dong , Zhu Yan Hong , Jin Xiao Feng , Chi Hao , Zheng Shilie , Zhang Xian Min
Published: August 2018

A comprehensive model for phase noise characteristics of an optoelectronic oscillator (OEO) is presented. The phase noise distributions of an OEO especially near the carrier are explained comprehensively, combining the Yao‐Maleki model and Leeson model. An experiment is carried on for verification of the OEO's phase noise distribution. Based on the comprehensive model, the phase noise distribution of an OEO can be predictably designed.
Analysis of amplification in a fiber ring resonator with a fabry‐perot cavity
Authors: Magalhães Regina , Silva Susana , Frazão Orlando
Published: August 2018

The placement of an Erbium‐doped Fiber Amplifier and a Fabry‐Perot cavity inside a fiber ring resonator can generate a sinusoidal modulation in the optical signal obtained. The characterization of this behavior is achieved by changing the length of the Fabry‐Perot cavity, which acts as a sensing device. A theoretical model of the optical signal modulation obtained with such configuration is also presented.
A new filtering monopole antenna with wideband harmonic suppression
Authors: Wei Zichun , Zhai Huiqing , Zhou Xiangyu , Zheng Licheng
Published: August 2018

In this letter, a new integrated filtering monopole antenna with wideband harmonic suppression is presented. In the design of the proposed antenna, a compact multiple harmonic suppression low pass filter is introduced and its stopband characteristic from 5 to 20 GHz is well integrated with the common monopole antenna. The final integrated filtering antenna can work from 2.88 to 4.02 GHz, and its wideband harmonic suppression successfully achieves 5.8 times of the central working frequency. The good performances of the present filtering antenna are shown by the simulated results and measured results, which could be a good candidate for the 5G anti‐interference wireless terminal communication system.
A novel low profile antenna array with high isolation performance
Authors: Xi Lei , Zhai Huiqing , Li Long
Published: August 2018

In this letter, a novel low profile antenna array with high isolation performance is proposed. The antenna realizes a low profile of 0.1λ0 by using artificial magnetic conductor (AMC) as the reflector. The antennas are compactly arranged on the AMC surface with a space of 0.5λ0. Two rows of metal through holes are placed in the middle of the AMC to prevent surface wave from propagating, thereby the coupling between the antennas is reduced. Simultaneously, isolation between the antennas is increased by more than 10 dB. And the prototype of the antenna array is fabricated and measured. Finally, the low profile antenna array with high isolation performance is verified by the simulated results and the measured results.
A compact coplanar waveguide Wilkinson power divider based on signal traces and adjacent grounds width modulation
Authors: Al Shamaileh Khair , Dib Nihad , Abushamleh Said
Published: August 2018

We propose a miniaturized coplanar waveguide Wilkinson power divider by varying the widths of the signal traces and grounds. Traces are expressed in terms of a truncated Fourier series. Simulated/measured input–output ports matching and isolation are below −15 dB, and the transmission parameters are −3 ± 0.1 dB at the design frequency.
Thermally enhanced GaN hybrid‐IC power amplifier using embedded IC process in a copper sheet
Authors: Yoon Tae‐Woong , Kim Dong‐Su , Yook Jong‐Min
Published: August 2018

This article introduces new packaging that improves the heat dissipation of RF power devices. Typically, power devices are mounted on a printed circuit board, in which the heat dissipation is made only through the bottom area of a device. The heat dissipation of the proposed structure is made through the bottom and side areas. As a result, proposed technology provides 30% improved heat dissipation in the RF GaN power amplifier. A copper sheet having a high thermal conductivity of around 400 W/mK is used as a core material to embed the power device. The measured results show that the drain efficiency of the fabricated X‐band power amplifier (PA) improved by about 13% in the proposed package structure.
A novel ultra‐wideband monopole antenna for ground penetrating radar application
Authors: Hendevari Maryam Samadpour , Pourziad Ali , Nikmehr Saeid
Published: August 2018

In this article, a novel monopole antenna for the ground penetrating radar applications is proposed. The antenna is a monopole bowtie with two slots and a defected ground plane, in order to improve the bandwidth. The proposed antenna shows a great bandwidth from 3.9 to 18 GHz which makes it to be an ultra‐wideband antenna. The overall size of the antenna is 14 × 22 × 1.6 mm3 on the FR4 substrate. Also, a prototype of the proposed antenna is fabricated. The measurement and simulation results are in good agreement.
Parallel ring‐line rat‐race circuit with very loose coupling
Authors: Kawai T. , Matsuda T. , Sakakura M. , Enokihara A.
Published: August 2018

This article describes rat‐race circuits (RRCs) in which a pair of ring‐lines have parallel lines of ±180‐degree difference for electrical length to realize the RRC with very loose coupling such as −10 dB or less. The proposed RRCs with parallel ring‐lines realize a coupling factor of −10 dB and −20 dB by using moderate characteristic impedance lines with a view point of fabrication tolerance for general PCB technologies. We confirm the validity of this circuit construction and design method using a commercial electromagnetic simulator and decide the circuit pattern for fabrication at a center frequency of 2.45 GHz. The fabricated RRCs with parallel ring‐lines realize the desired coupling factors and in‐/out‐of‐phase outputs, and the measurement results of scattering parameters for −10 dB and −20 dB RRCs are in good agreement with the simulation results.
A novel 1‐to‐3 feeding network with radiation contribution
Authors: Hou Yuefeng , Zhang Zhijun , Feng Zhenghe
Published: August 2018

The feeding network is an essential part of the series‐fed microstrip array antenna. It needs additional space on the substrate or even extra layer of the substrate. However, the traditional feeding network has no contribution to the gain, which will result in an unnecessary waste of space. In this letter, a novel 1‐to‐3 feeding network combining with radiated patches is presented. To the best of the authors’ knowledge, the feeding network with radiation contribution is reported for the first time. The modified feeding network can feed antenna and radiate energy at the same time. To verify the design strategy, a series‐fed microstrip array antenna with the proposed radiated feeding network is designed. Compared with the series‐fed microstrip array antenna with traditional feeding network, a 15.3% higher gain is obtained by the proposed antenna. Finally, a prototype of the proposed antenna is fabricated and tested. Measured results show that the antenna works in a band from 9.41 to 10.18 GHz. The measured peak gain is 19.75 dBi at 10 GHz. A good agreement between simulated and measured results is achieved.
A compact CPW‐fed tapered monopole triple‐band antenna for WLAN/WiMAX application
Authors: Pandit Vivek Kumar , Harish A. R.
Published: August 2018

A coplanar waveguide (CPW)‐fed very compact triple‐band, low profile planar monopole antenna for WLAN/WiMAX application is proposed. The proposed antenna consists of two V‐shaped and two open ended inverted L‐shaped slots in a tapered monopole attached to a tapered CPW feed line. The antenna operates in the 2.4/5.2/5.5‐GHz WLAN and 3.5/5.5‐GHz WiMAX bands and has very compact size of 18 × 22 × 0.5 mm3 (0.135λ0 × 0.165λ0 × 0.0037λ0). In addition, the proposed antenna has omnidirectional radiation pattern, high reflection outside the desired bands, and stable gain over each band. The antenna has been fabricated and tested and the measured results agree well with the simulation results.
A 5 GHz narrow‐beam leaky‐wave antenna using binomially distributed slot based substrate integrated waveguide
Authors: Farooq Memoona , Khan Muhammad U. , Cheema Hammad M.
Published: August 2018

This article presents a planar substrate integrated waveguide based leaky wave antenna (LWA) with narrow beamwidth, high directivity, and low side lobe levels (SLL). Through first‐time use of binomially distributed slots, a significant decrease in SLL along with a small form factor is achieved. Designed on a Rogers 5880 substrate, the proposed design occupies 250 × 45 mm2 exhibiting a beamwidth of 11.3° and sidelobe level less than −10 dB at 5.6 GHz. In comparison with conventional LWA with uniform slots, a 63% size reduction is also achieved.
Highly selective bandpass filter using substrate integrated waveguide technology for FMCW radar application
Authors: Vala Alpesh , Patel Amit
Published: August 2018

A bandpass filter using substrate integrated waveguide technology is proposed in this paper for ISM band frequency (5.7–5.9 GHz) application. Metallic inductive posts are used for the realization of the filter. The proposed structure provides pass band from the frequency range of 5.72 GHz to 5.84 GHz with the insertion loss of 0.7 dB and return loss more than 25 dB. Frequency tuning is carried out from the frequency range of 5.65 GHz to 6.06 GHz with the variation of pass band bandwidth from 88 MHz to 222 MHz. All the simulations are carried out by high frequency structure simulator based on FEM method software. Proposed bandpass filter is fabricated and measured result indicates better performance. It will be utilized in the system developed at CSRTC for the suppression of higher order harmonics in frequency modulated continuous wave radar at the frequency from 5.725 GHz to 5.875 GHz.
On the computation and comparison of specific absorption rate (SAR) in a skin tissue using analytical and numerical methods
Authors: Asif Sajid M. , Iftikhar Adnan , Maile Keith , Ewert Daniel L. , Braaten Benjamin D.
Published: August 2018

Specific absorption rate (SAR) is a measure of safety and a requirement for portable radio frequency devices which are regulated mainly by the standards recommended by the Institute of Electrical and Electronics Engineers (IEEE) and International Commission on Non‐Ionizing Radiation Protection (ICNIRP). Accurate approximation of SAR is therefore important for safety as well as for compliance purposes. This article presents the analytical representation and derivation of the SAR from the basics of electromagnetic theory, Maxwell Equations, and law of conservation of energy in electromagnetic theory. It is shown, analytically, that for a time harmonic electromagnetic wave propagating in a homogeneous lossy medium having permittivity ϵ, permeability µ, and conductivity σ, the time rate change of electric and magnetic energy densities at steady state inside a given volume is zero. It is also shown that at the steady state, the net power flowing through a volume, bounded by a surface is equal to the power dissipated in that volume. Furthermore, this work demonstrates that at the steady state, SAR can be represented in terms of power density or in terms of power dissipated in the given volume. Moreover, calculation of SAR for a 1 mm × 1 mm × 0.01 m box having the dielectric properties of human skin was performed using the derived formulas and then compared with the numerical results, obtained using a full wave 3D simulation tool, HFSS. A good agreement was found between the analytical and numerical results.
U‐shaped stacked structure monolithic transformer for efficiency improvement
Authors: Kang Sungyoon , Kim Minchul , Kim Junghyun
Published: August 2018

This article presents a novel monolithic transformer (TF) structure, which is designed to improve TF efficiency by enhancing the quality factor of the metal trace. When the number of thick metal layers is limited in semiconductor technology, it is necessary to use thin metals that have lower quality factors to form the TF coil, which degrades TF efficiency. To overcome this limitation, supplementary walls of metal and a via are connected along both sides of the thin metal to form a U‐shaped metal trace, which in turn improves the quality factor and TF efficiency. The proposed structure does not require additional metal layers, other than the metal layers used in the TF configuration. Thus, the proposed structure is widely applicable to all semiconductor technologies, including those that provide only a small number of metal layers. To assess and validate this proposed structure, we fabricated a set of TFs including conventional structures using gallium arsenide (GaAs) technology, which is the most widely used technology in mobile power amplifier (PA) fabrication. The proposed structure was successfully demonstrated to effectively improve the TF efficiency by as much as 8.6% and 6.5% in comparison to a conventional planar structure and a stacked structure, respectively.
A linearity‐improved multi‐band envelope tracking Tx power amplifier under antenna mismatch for mobile applications
Authors: Ji Donghyeon , Jeon Jooyoung , Kim Junghyun
Published: August 2018

A linearity‐improved multi‐band envelope tracking power amplifier (ET PA) with digital predistortion (DPD) under antenna mismatch is introduced based on the advanced mismatch detection and correction technique. An advanced tunable output matching network (TOMN) is utilized to correct the mismatch and to reconfigure the operating band, simultaneously. An advanced phase shifter and an operating algorithm are newly proposed to detect mismatch on the multi‐band PA and are realized as a compact integrated circuit (IC), facilitating self‐contained operation without external control. The mismatch detector and RF switches for the TOMN were integrated into a single IC using silicon on insulator (SOI) CMOS, which was integrated with a 2‐μm InGaP/GaAs HBT PA monolithic microwave integrated circuit (MMIC) into a single module. With long‐term evolution (LTE) signal, the fabricated ET PA demonstrates a linearity improvement of 2–2.4 dB under 2.5:1 voltage standing wave ratio.
Novel slot‐coupled broadband waveguide junction for orthomode transducer using mirrored semi‐profiled section
Authors: Pandya Jigar M. , Sood Khagindra , Pujara Dhaval
Published: August 2018

This article proposes the waveguide junction for an orthomode transducer (OMT) with ≈35% realized bandwidth in waveguide slot‐coupled configuration employing a profiled taper/branching region. A wideband impedance match is achieved using a new mirror image concept while constructing the profile from a specified mathematical function. Numerical simulation and experimental verification were carried out for the proposed OMT and good agreements are achieved. This modified configuration provides broader bandwidth compared to the conventional waveguide slot‐coupled OMT's (% bandwidth ≈27%) reported till date. The proposed waveguide junction can be used in multi‐frequency, multi‐band high‐performance antennas and feed systems.
Liquid metamaterial based radome design
Authors: Patel Shobhit K. , Kosta Y.P. , Charola Shreyas
Published: August 2018

We present liquid metamaterial based radome design. Radome is a layer used to protect antenna from weather disturbances. The addition of this layer reduces the gain of antenna. Our aim here is to improve this gain. Liquid metamaterial based radome presented in the manuscript improves the gain performance of antenna. The designed liquid metamaterial radome structure is applied to patch antenna for its performance observation. Antenna design with and without liquid metamaterial radome is tested in this manuscript. The design results in the form of return loss, bandwidth and gain are measured and compared. From the comparison, it is evident that the design with liquid metamaterial radome improves the gain of the antenna. The designed antenna with metamaterial liquid radome is applicable in narrowband sensitive radar antenna applications.
A miniaturized triple band monopole antenna with a coupled branch strip for bandwidth enhancement for IoT applications
Authors: Chung Ming‐An
Published: August 2018

A miniaturized monopole antenna with multiband operations for LTE, WWAN, WiMAX, and WLAN applications is presented. The antenna consists of multibranch strips and is fabricated on both sides of the FR4 substrate, which has a compact size of 10(L) ×10(W) ×0.8(T) mm3 to be embedded inside the Internet of Things (IoT) device as an internal antenna. Three operating bands covering 2.3–2.69, 3.4–3.7, and 5.15–5.85 GHz for the LTE, WWAN, WiMAX (2.3/2.5/3.5 GHz), and WLAN (2.4 GHz) systems are achieved with good radiation efficiencies. The proposed antenna can be embedded in the IoT device for the LTE, WWAN, WiMAX, and WLAN applications. The proposed antenna has advantages of sided structure, easy fabrication, low cost, and multiband operation. Also, the impedance matching performance of 3 resonant modes for the antenna can be adjusted flexibly. This makes the proposed antenna design suitable for practical applications. Details of the design process and the experimental results of the constructed antenna are presented.
Development of deep neural network for individualized hepatobiliary toxicity prediction after liver SBRT
Authors: Ibragimov Bulat , Toesca Diego , Chang Daniel , Yuan Yixuan , Koong Albert , Xing Lei
Published: August 2018

Background

Accurate prediction of radiation toxicity of healthy organs‐at‐risks (OARs) critically determines the radiation therapy (RT) success. The existing dose–volume histogram‐based metric may grossly under/overestimate the therapeutic toxicity after 27% in liver RT and 50% in head‐and‐neck RT. We propose the novel paradigm for toxicity prediction by leveraging the enormous potential of deep learning and go beyond the existing dose/volume histograms.

Experimental Design

We employed a database of 125 liver stereotactic body RT (SBRT) cases with follow‐up data to train deep learning‐based toxicity predictor. Convolutional neural networks (CNNs) were applied to discover the consistent patterns in 3D dose plans associated with toxicities. To enhance the predicting power, we first pretrain the CNNs with transfer learning from 3D CT images of 2644 human organs. CNNs were then trained on liver SBRT cases. Furthermore, nondosimetric pretreatment features, such as patients’ demographics, underlying liver diseases, liver‐directed therapies, were inputted into the fully connected neural network for more comprehensive prediction. The saliency maps of CNNs were used to estimate the toxicity risks associated with irradiation of anatomical regions of specific OARs. In addition, we applied machine learning solutions to map numerical pretreatment features with hepatobiliary toxicity manifestation.

Results

Among 125 liver SBRT patients, 58 were treated for liver metastases, 36 for hepatocellular carcinoma, 27 for cholangiocarcinoma, and 4 for other histologies. We observed that CNN we able to achieve accurate hepatobiliary toxicity prediction with the AUC of 0.79, whereas combining CNN for 3D dose plan analysis and fully connected neural networks for numerical feature analysis resulted in AUC of 0.85. Deep learning produces almost two times fewer false‐positive toxicity predictions in comparison to DVH‐based predictions, when the number of false negatives, i.e., missed toxicities, was minimized. The CNN saliency maps automatically estimated the toxicity risks for portal vein (PV) regions. We discovered that irradiation of the proximal portal vein is associated with two times higher toxicity risks (risk score: 0.66) that irradiation of the left portal vein (risk score: 0.31).

Conclusions

The framework offers clinically accurate tools for hepatobiliary toxicity prediction and automatic identification of anatomical regions that are critical to spare during SBRT.
Regularization strategies in statistical image reconstruction of low‐dose x‐ray CT: A review
Authors: Zhang Hao , Wang Jing , Zeng Dong , Tao Xi , Ma Jianhua
Published: August 2018

Statistical image reconstruction (SIR) methods have shown potential to substantially improve the image quality of low‐dose x‐ray computed tomography (CT) as compared to the conventional filtered back‐projection (FBP) method. According to the maximum a posteriori (MAP) estimation, the SIR methods are typically formulated by an objective function consisting of two terms: (a) a data‐fidelity term that models imaging geometry and physical detection processes in projection data acquisition, and (b) a regularization term that reflects prior knowledge or expectations of the characteristics of the to‐be‐reconstructed image. SIR desires accurate system modeling of data acquisition, while the regularization term also has a strong influence on the quality of reconstructed images. A variety of regularization strategies have been proposed for SIR in the past decades, based on different assumptions, models, and prior knowledge. In this paper, we review the conceptual and mathematical bases of these regularization strategies and briefly illustrate their efficacies in SIR of low‐dose CT.
Benchmarking the DACS‐integrated Radiation Dose Monitor® skin dose mapping software using XR‐RV3 Gafchromic® films
Authors: Habib Geryes Bouchra , Hadid‐Beurrier Lama , Waryn Marie‐Joséphine , Jean‐Pierre Antonella , Farah Jad
Published: August 2018

Purpose

To perform a benchmark of a new DACS‐integrated patient skin dose mapping solution using on‐phantom measurements with Gafchromic® films.

Materials and methods

To calculate cumulative patient skin dose distribution with 1‐cm2 resolution, a Radiation Dose Monitor (RDM, Medsquare), using the Radiation Dose Structured Report (RDSR), tabulated backscatter and mass energy absorption coefficients together with site‐specific corrections for table, mattress attenuation, and air kerma calibration factor. Peak skin dose (PSD) and two‐dimensional (2D) skin dose distributions calculated with RDM were compared against on‐phantom measurements with XR‐RV3 Gafchromic® films considering two widely used x‐ray equipment. Seventeen different settings which include simple and multiple beam projections with extreme angulations (up to 75°), all available fields‐of‐view (FOVs 48–11 cm), additional collimation, variable table height and lateral positions, and variable phantom thickness (12, 20, and 30 cm) were involved.

Results

Due to a careful calibration of films using clinical beam qualities, 22.8% (k = 2) overall measurement uncertainty was achieved. Calculated and measured PSD values agreed with an average difference of 10% ± 7% and 9% ± 7% for 34 test conditions performed on Siemens Artis Zee and GEMS Innova IGS interventional systems, respectively. Finally, RDM's 2D skin dose maps closely matched those registered on XR‐RV3 films considering the 1‐cm2 resolution. While RDM correctly reproduced beam overlapping due to variable tube projections, FOV, table positions, etc., few challenges were identified related to conversion of rectangular fields to square areas in the RDSR and a stair‐step effect visible for large tube projections (>45°).

Conclusion

The accuracy of RDM's DACS‐integrated skin dose mapping software was acceptable considering measurement uncertainties associated with Gafchromic® films.
Predicting lesion size by accumulated thermal dose in MR‐guided focused ultrasound for essential tremor
Authors: Huang Yuexi , Lipsman Nir , Schwartz Michael L. , Krishna Vibhor , Sammartino Francesco , Lozano Andres M. , Hynynen Kullervo
Published: August 2018

Purpose

To correlate the accumulated thermal dose (ATD) with lesion size in magnetic resonance (MR)‐guided focused ultrasound (MRgFUS) thalamotomy to help guide future clinical treatments.

Materials and Methods

Thirty‐six patients with medication‐refractory essential tremor were treated using a commercial MRgFUS brain system (ExAblate 4000, InSightec) in a 3T MR scanner (MR750, GE Healthcare). Intraoperative MR‐thermometry was performed to measure the induced temperature and thermal dose distributions (thermal coefficient = −0.00909 ppm/°C). The ATD was calculated over multiple sonications with appropriate corrections for spatial‐shifting artifacts. The ATD profile sizes obtained for dose values of 17, 40, 100, 200, and 240 cumulative equivalent minutes at 43°C (CEM) were correlated with the corresponding lesion sizes measured via axial T1‐ and T2‐weighted MR images acquired 1 day post‐treatment.

Results

Of a total of 232 included sonications, 83 required corrections for off‐resonance‐induced spatial‐shifting artifacts (correction range = [1.1,2.2] mm). The mean lesion sizes measured on T2‐weighted MR images (6.2 ± 1.3 mm, mean ± SD) were 15% larger than those measured on corresponding T1‐weighted MR images (5.3 ± 1.2 mm, mean ± SD). The ATD values that provided the best correlations with the measured lesion sizes on T2‐ and T1‐weighted MR images were 100 and 200 CEM, respectively.

Conclusion

The ATD was correlated with lesion size measured 1 day following MRgFUS thalamotomy for essential tremor. These data provide useful information for predicting brain lesion size and determining treatment endpoints in future clinical MRgFUS procedures.
Gene alterations and expression spectrum of SPATA33 in nonobstructive azoospermic Iranian men
Authors: Monsef Ladan , Borjian Boroujeni Parnaz , Totonchi Mehdi , Sabbaghian Marjan , Mohseni Meybodi Anahita
Published: August 2018

Genetic abnormalities have been considered a significant cause of male infertility. Increased expression of SPATA33 during the first wave of spermatogenesis indicates its possible association with the meiotic process. The aim of the current study was to investigate the genetic variations in the SPATA33 gene and its expression in patients with nonobstructive azoospermia (NOA). A total of 100 Iranian NOA men with idiopathic infertility were taken as the case group. The control group comprised 100 fertile men who had at least one child. The presence of nucleotide variations was analyzed in both groups using the standard polymerase chain reaction (PCR) sequencing technique. For mRNA and protein expression studies, testicular biopsy specimens from 27 patients were subdivided into three groups: nine obstructive azoospermic patients with hypospermatogenesis as control; nine maturation arrest (MA) and nine Sertoli cell‐only syndromes (SCOS) as case groups. The expression of SPATA33 at both mRNA and protein levels was compared among these three groups using the reverse transcription PCR technique, the realtime‐PCR technique, and immunohistochemistry. Mutation analysis of the
SPATA33 gene revealed five nucleotide changes among the population studied. All but one showed no significant differences between the groups. The genotype distributions of rs112536073A > T in the transcription factor binding site region with heterozygote and homozygote genotypes were significantly different (
p < 0.05) between the two groups. More heterozygotes of this polymorphism were observed in patients, whereas more homozygotes were detected in controls. Accordingly, the current study illustrated that alterations in
SPATA33 gene, at least those found in this study, may not impair spermatogenesis in patients with NOA. Reduction of gene expression at the level of mRNA in patients with SCOS can be interpreted by the absence of germ cells in the testicular tissue of these patients.
Estimation of visceral fat in 9‐ to 13‐year‐old girls using dual‐energy X‐ray absorptiometry (DXA) and anthropometry
Authors: Lee V. , Blew R. , Hetherington‐Rauth M. , Blew D. , Galons J.‐P. , Hagio T. , Bea J. , Lohman T. , Going S.
Published: August 2018

Objectives

Accumulation of visceral fat (VF) in children increases the risk of cardiovascular disease and type 2 diabetes, and measurement of VF in children using computed tomography and magnetic resonance imaging (MRI) is expensive. Dual‐energy X‐ray absorptiometry (DXA) may provide a low‐cost alternative. This study aims to determine if DXA VF estimates can accurately estimate VF in young girls, determine if adding anthropometry would improve the estimate and determine if other DXA fat measures, with and without anthropometry, could be used to estimate VF in young girls.

Methods

Visceral fat was measured at lumbar intervertebral sites (L1–L2, L2–L3, L3–L4 and L4–L5) using 3.0T MRI on 32 young girls (mean age 11.3 ± 1.3 years). VF was estimated using the GE CoreScan application. Measurement of DXA android and total body fat was performed. Weight, height and waist circumference (WC) measurements were also obtained.

Results

Waist circumference and body mass index were both strongly correlated with MRI, although WC was the best anthropometric covariate. Per cent fat (%fat) variables had the strongest correlation and did best in regression models. DXA %VF (GE CoreScan) and DXA android %fat and total body %fat accounted for 65% to 74% of the variation in MRI VF.

Conclusion

Waist circumference predicted MRI VF almost as well as DXA estimates in this population, and a combination of WC and DXA fat improves the predictability of VF. DXA VF estimate was improved by the addition of WC; however, DXA android %fat with WC was better at predicting MRI VF.
Superhydrophobic PCL/PS composite nanofibrous membranes prepared through solution blow spinning with an airbrush for oil adsorption
Authors: Lv Ju , Yin Xueqiong , Li Rongguo , Chen Junhua , Lin Qiang , Zhu Li
Published: August 2018

Superhydrophobic composite nanofibrous membranes(PP) were prepared from polycaprolactone (PCL)/polystyrene (PS) through solution blow spinning with an airbrush for oil adsorption. PP membranes were characterized by fourier transform infrared spectroscopy, scanning electron microscopy, water contact angle, X‐ray Photoelectron Spectroscopy, X‐ray diffractometer, and thermogravimetric analysis instrument. The effects of mass ratio of PCL and PS on the morphology, porosity, density, cyrstallinity, thermal stability, and oil adsorption ability were investigated. PP membranes had higher density than PCL and PS, while better hydrophobicity. The saturation adsorption capacity of PP to peanut oil, motor oil, and diesel oil is 16.89 g/g, 20.33 g/g, and 12.17 g/g, respectively. After 6 cycles of reutilization, the adsorption capacity to peanut oil, motor oil, and diesel oil remained at 6.16, 7.46, and 5.33 g/g, respectively, higher than that of pure PCL membrane.The water/oil adsorption selectivity of PP was about 7:100. PP had higher oil adsorption capacities and better water/oil adsorption selectivity than the commercial oil absorbent polypropylene. PP membrane could be prepared and used in situ to separate oil from oil/water mixture. POLYM. ENG. SCI., 59:E171–E181, 2019. © 2018 Society of Plastics Engineers
Intranasal Lidocaine for Acute Management of Primary Headaches: A Systematic Review
Authors: Dagenais Renée , Zed Peter J.
Published: August 2018

Intranasal lidocaine has been studied and recommended as an alternative in the management of acute headache. The objective of this systematic review was to evaluate the efficacy and safety of intranasal lidocaine in the acute management of primary headaches. The MEDLINE (1946 to May 2018), EMBASE (1974 to May 2018), Cochrane Central Register of Controlled Trials (2008 to May 2018), Cumulative Index to Nursing and Allied Health Literature (CINAHL) (1982 to May 2018), and ClincialTrials.gov online databases were searched. Studies conducted in patients with acute primary headache were included if lidocaine was compared with placebo or alternative treatments, lidocaine dosing was specified, and patients’ pain before and after treatment were clearly reported. Six studies met the inclusion criteria. Intranasal lidocaine demonstrated potential benefit over placebo in acute pain reduction and need for rescue medication only in the four studies deemed to be of poor quality, not in the two fair‐quality studies. No study reported benefit in preventing headache recurrence or repeat visits to the emergency department. Lidocaine was associated with significantly higher rates of adverse events compared with placebo and may result in lower rates of patient satisfaction. There is insufficient evidence to support the use of intranasal lidocaine in acute management of primary headaches. Further research is warranted to better elucidate whether intranasal lidocaine has a role in the management of specific primary headache subtypes and whether there is an optimal regimen.
Association between Development of Dementia and Use of Benzodiazepines: A Systematic Review and Meta‐Analysis
Authors: Lucchetta Rosa Camila , da Mata Barbara Paes Miglioli , Mastroianni Patricia de Carvalho
Published: August 2018

Study Objective

The use of benzodiazepines and the development of dementia is controversial, with studies indicating that benzodiazepines could be either a protective factor or a risk factor for dementia, or no association may exist between the two. Our objective was to identify whether such an association exists.

Design

Systematic review and meta‐analysis of 12 prospective and retrospective cohort studies and case‐control studies.

Participants

A total of 981,133 (in the systematic review) and 980,860 (in the meta‐analysis) adults or elderly individuals.

Measurements and Main Results

A search of the PubMed, LILACS, and Cochrane Central Register of Controlled Trials databases, as well as a manual search of the reference lists of the included publications and reviews, was performed. We included studies that reported the incidence of dementia and in ever users of benzodiazepines. Data were analyzed by using a random effects model in R software. Quality of the evidence was assessed with the Grading of Recommendations Assessment, Development and Evaluation (GRADE) certainty ratings system. The results of the main meta‐analysis suggest that benzodiazepines can be a risk factor for developing dementia (odds ratio 1.38, 95% confidence interval 1.07–1.77; I2 = 98%; 95% prediction interval 0.58–3.25; very low certainty).

Conclusion

Our results suggest an association between the use of benzodiazepines and the development of dementia. However, the current evidence lacks the power to infer differences between the effects of Alzheimer's disease and vascular dementias, long‐acting and short‐acting benzodiazepines, and various exposure loads (duration and dose). Future long‐term prospective cohort studies are necessary, with adequate adjustments for confounding variables, strategies to minimize reverse causality, reporting of subgroups aimed at greater homogeneity of findings, adequate statistical power to identify high‐magnitude effects, and defined daily dose analyses for dose‐response gradient.
Flavin oxidation in flavin‐dependent N‐monooxygenases
Authors: Robinson Reeder M. , Klancher Catherine A. , Rodriguez Pedro J. , Sobrado Pablo
Published: August 2018

Siderophore A (SidA) from Aspergillus fumigatus is a flavin‐containing monooxygenase that hydroxylates ornithine (Orn) at the amino group of the side chain. Lysine (Lys) also binds to the active site of SidA; however, hydroxylation is not efficient and H2O2 is the main product. The effect of pH on steady‐state kinetic parameters was measured and the results were consistent with Orn binding with the side chain amino group in the neutral form. From the pH dependence on flavin oxidation in the absence of Orn, a pKa value >9 was determined and assigned to the FAD‐N5 atom. In the presence of Orn, the pH dependence displayed a pKa value of 6.7 ±0.1 and of 7.70 ±0.10 in the presence of Lys. Q102 interacts with NADPH and, upon mutation to alanine, leads to destabilization of the C4a‐hydroperoxyflavin (FADOOH). Flavin oxidation with Q102A showed a pKa value of ~8.0. The data are consistent with the pKa of the FAD N5‐atom being modulated to a value >9 in the absence of Orn, which aids in the stabilization of FADOOH. Changes in the FAD‐N5 environment lead to a decrease in the pKa value, which facilitates elimination of H2O2 or H2O. These findings are supported by solvent kinetic isotope effect experiments, which show that proton transfer from the FAD N5‐atom is rate limiting in the absence of a substrate, however, is significantly less rate limiting in the presence of Orn and or Lys.
Impacts of LEOGEO Atmospheric Motion Vectors on East Asian weather forecasts
Authors: Lee Sihye , Song Hyo‐Jong
Published: August 2018

A study has been carried out to investigate the impact of the assimilation of Atmospheric Motion Vectors (AMVs) derived from the combination of LEO and GEO images (LEOGEO AMVs) on the accuracy of global model forecasts over East Asia for January 2017. In the cycled analysis and forecast experiments, the assimilation of LEOGEO AMVs shows globally significant benefits in wind analysis over the 50–70° latitude band for all levels in both hemispheres. Even though its spatial coverage is confined to higher latitudes and the observable variable is wind, not mass, the assimilation of LEOGEO AMVs has a positive impact on the synoptic patterns represented by surface pressure weather charts over the East Asian domain. A bootstrapping technique was used for testing the statistical significance of the positive impact of the LEOGEO AMVs. Forecasts for the wind and, as a delayed response, temperature and surface pressure in the experiment assimilating the LEOGEO AMVs were improved compared to those in the control experiment without LEOGEO AMVs with a two‐tailed 90% statistical significance.