bluuebunny/crossref_metadata_2025 huggingface dataset:
Metamaterials microstrip patch antenna for wireless communication RFID technology
Authors: Naoui Seif , Latrach Lassaad , Gharsallah Ali
Published: March 2015

This article is specialized to highlight the method of miniaturization and improvement the patch antenna using the complementary metamaterial. This method is presented by two different techniques. The first technique is composed a structure of patch antenna integrated in its surface a cell of complementary split ring resonator. This resonator is placed at the middle of the radiating patch in parallel with the transmission line and with a variable angle of orientation. The objective is to find the ultimate angle where the best results are obtained on improving the characteristics of the considered antenna. This motif widespread at the traceability applications by wireless communication for RFID technology at the operation frequency 2.45 GHz. In the second technique, were integrated at the surface of antenna a homogeneous and periodic array of complementary split ring resonators using the same position and the supreme orientation found in early studies. The advantage of the latter technique is to indicate the effect of increasing the number of resonators on the performance patch antenna and show the specifications and characterization of each technique proportionally at the two interesting factors miniaturization and improvement. Our contribution is based on studies and empirical and theoretical tests often presented in this article. All simulation results were made by the CST Microwave Studio. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:1060–1066, 2015
Compact CPW‐fed half‐ring‐shaped slot antenna for harmonic suppression applications
Authors: Yeo Junho , Lee Jong‐Ig
Published: March 2015

A compact half‐ring‐shaped (HRS) slot antenna fed by a coplanar waveguide (CPW) transmission line for harmonic suppression applications is presented. The antenna consists of an HRS slot and stepped impedance resonators (SIRs) symmetrically appended to the slot at both ends. Two SIRs are used to suppress the harmonics of the fundamental resonance frequency with an additional effect of size reduction. The optimized HRS slot antenna with SIRs operating at 2.45 GHz is fabricated on an FR4 substrate with dimensions of 30 mm by 30 mm, and its performance is compared to that of a conventional rectangular slot antenna. The slot length of the proposed harmonic‐suppressed slot antenna is reduced by 45% compared to a conventional rectangular slot antenna owing to the HRS slot and appended SIRs. Experiment results show that the proposed antenna has the desired impedance characteristic with a frequency band of 2.39–2.49 GHz for a voltage standing wave (VSWR) < 2, and a measured gain of 1.5 dBi at 2.45 GHz. In addition, the suppression of the second, third, and fourth harmonics are successfully demonstrated. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:1102–1104, 2015
A frequency reconfigurable mimo antennas using RF tuning element for mobile handset
Authors: Lee Won‐Woo , Cho Yong‐Sang
Published: March 2015

In this letter, we develop a frequency tunable multiple‐input multiple‐output antenna for handhelds to achieve both the wideband tunability at the frequency ranges of 704–960 MHz and low correlation properties over the tuning frequencies. The proposed antenna covers various long‐term evolution (LTE) service bands: Band 17 (704–746 MHz), Band 13 (746–787 MHz), Band 5 (824–894 MHz), and Band 8 (880–960 MHz). The proposed LTE antennas are based on a switch‐loaded antenna structure, with a resonance frequency that can be controlled by a logic circuit. The tuning technique for the LTE antenna uses a SP4T RF switch to match the impedances to realize the bands of interest. The proposed main antenna consists of an inverted‐F antenna (IFA), the LTE subantenna is loop antenna structure. The use of two different antenna types of IFA and loop antenna achieves high isolation. We show that the proposed antenna has envelop correlation coefficient value as low as 0.5 over the designed frequency tuning ranges. The proposed antenna was fabricated and tested for experimental verification. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:1092–1096, 2015
Multimode wideband diplexer using open‐ and short‐ended stub‐loaded hairpin resonator
Authors: Wu Bian , Qiu Feng
Published: March 2015

A fourth‐order multimode wideband diplexer with high selectivity and compact size is presented in this article. The open‐ or short‐ended stub‐loaded hairpin resonator (SLHR) is utilized to split one resonant mode to even‐mode and odd‐mode. A pair of SLHRs splits the two modes to four modes and also introduces two transmission zeros for each channel due to the mixed coupling. Using two kinds of SLHRs at the two filtering channel, a compact multimode wideband diplexer with center frequencies at 2.1 GHz/2.5 GHz and fractional bandwidths of 10.5%/8.5% are designed and fabricated. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:1096–1099, 2015
An asymmetric split ring resonator for refractive‐based‐sensor applications at terahertz frequencies
Authors: Wu Dong‐Wei , Chen Hang
Published: March 2015

We have proposed a terahertz metamaterials resonator that consists of a pair of split ring resonators (SRRs) and can be utilized as a refractive‐based‐sensor. Supporting simulations indicate the resonant Q value is up to 90 and a refractive sensitivity of 61.7 GHz/RIU, figure of merit value of 10.74, correspondingly. Resonator sample of the “connected SRR” has been fabricated and measured using a terahertz time‐domain spectroscopy system, the transmission characteristics of which are consistent basically with the finite difference time domain simulations. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:1132–1135, 2015
Study on pattern synthesis of conformal array using enhanced adaptive genetic algorithm
Authors: Seong Cheol‐Min , Park Dong‐Chul
Published: March 2015

Investigations on an enhanced adaptive genetic algorithm (EAGA) for pattern synthesis of a conformal array are presented. The proposed algorithm uses the advantages of the adaptive genetic algorithm (AGA) and the invasive weed optimization so that it improves the searching ability and the convergence speed. Convergence characteristics of the EAGA are compared with those of the AGA. Also, the pattern synthesis performance of the EAGA is compared with that of the AGA. A 4 × 16 conformal array operating as a 1 × 16 array in the azimuth direction is fabricated and measured to demonstrate the proposed algorithm. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:1173–1176, 2015
A fundamental OOK modulator for 340 GHz communication using 0.13 μm CMOS technology
Authors: Deng Xiao‐Dong , Li Yihu , Wu Wen , Xiong Yong‐Zhong
Published: March 2015

This letter presents a 340 GHz fundamental on–off keying modulator using 0.13 μm CMOS technology. The proposed modulator topology is composed of a 90° hybrid coupler and two series loads formed by a series inductor and a MOSFET for 340 GHz on‐/off‐state switching. The measured results indicate that the insertion loss is ∼4.9 dB on average and the isolation is better than 13 dB from 330 to 347 GHz. A measured data rate of 2.5 Gb/s is demonstrated at the carrier frequency of 340 GHz. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:1166–1168, 2015
A compact meta‐atom for dual band negative permittivity metamaterial
Authors: Sarkhel Abhishek , Mitra Debasis , Paul Sandip , Chaudhuri Sekhar Ranjan Bhadra
Published: March 2015

In this letter, a compact design of electric meta‐atom has been proposed as a dual band negative permittivity metamaterial. Compared with the earlier work, the proposed dual band meta‐atom has a better coupling strength at both the resonances and it is also more compact. This dual band design utilizes the mechanism of the resonance coupling between a meander line loaded delta loop meta‐atom and a rectangular close ring meta‐atom. The proposed meta‐atom is designed and investigated by both simulation and experiment with good agreement. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:1152–1156, 2015
Broadband slotted patch antennas with circular polarization
Authors: Chen Jhih‐Ming , Row Jeen‐Sheen
Published: March 2015

A design for circularly polarized (CP) patch antennas with broadband operation is described and studied. The design is based on a traditional cross slot antenna excited with a microstrip line through coupling. It is found that when the ground plane of the cross slot antenna, namely the slotted patch has a specific aspect ratio, the CP radiation with a 3‐dB‐axial‐ratio bandwidth of more than 30% can be generated. For such a slotted patch antenna, parametric analyses are performed to demonstrate how to achieve the broadband CP operation in a limited area. Simulated and measured results for the performances of the constructed prototype are also shown. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:1140–1143, 2015
A miniaturized quad‐band bandstop filter with high selectivity based on shunt‐connected, T‐shaped stub‐loaded, stepped‐impedance resonators
Authors: Adhikari Kishor Kumar , Kim Nam Young
Published: March 2015

This letter presents a microstrip quad‐band bandstop filter (QBBSF) with a miniaturized size and high selectivity. The structure of the proposed QBBSF consists of two‐folded, shunt‐connected trisection stepped‐impedance resonators (TSSIRs). One of these TSSIRs, which operates on the second and fourth central frequencies, has been embedded inside another TSSIR operating at the first and third central frequencies of the proposed QBBSF. Characterized by equivalent circuit analysis and full‐wave EM simulations, each TSSIR has been miniaturized by a T‐shaped stub load. The main advantage of the proposed QBBSF lies in its central frequencies, which can be adjusted conveniently within a wide range by varying parameters of TSSIRs, the positions, and dimensions of the stub loads. A protocol QBBSF with a compact size of 0.0115 λg2 operating at central frequencies of 1.90, 3.32, 5.77, and 6.75 GHz was designed, simulated, and fabricated to verify the proposed method. The measured minimum stop band return loss of 21.4 dB and maximum pass band insertion loss of 0.66 dB indicated the excellent in‐band and out of band selectivity of the proposed QBBSF. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:1129–1132, 2015
Wideband fiber‐optic delay line with dynamic delay drift compensation
Authors: Qi Xiaoqiong , Xie Liang , Wang Hui
Published: March 2015

A wideband and high resolution fiber delay line system based on a self‐fabricated distributed‐feedback (DFB) laser is demonstrated in this article, where the delay time drift due to temperature variance is compensated using the extensibility of the standard single‐mode fiber (SMF). The DFB laser with the amplitude bandwidth of 18 GHz and the in‐band phase variance within 60° is applied as the optical source to provide wideband microwave signal delay. The temperature‐dependence delay variance is measured up to 42.8 ps/km/°C in SMF delay line. A compensation capability of 600 ps is reached with a fiber stretcher acted on a motor‐driven 300 m SMF. The proposed system not only provides delay drift compensation for the environmental‐sensitive systems, but also a feasible solution to realize continuously tuning of delay for stable systems. The tunable range of the microwave delay could be further extended using longer stretched fiber. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:1219–1222, 2015
Design of differential wideband bandpass filters with miniaturized size based on dual‐mode defected ground structure
Authors: Li Lin , Yang J.‐X. , Bao Jia , Du J.‐J.
Published: March 2015

Dual‐mode defected ground structure (DGS) is presented to construct differential wideband bandpass filter (WBPF) with very compact size. This proposed DGS is composed of an etched rectangular loop with a central zigzag tapered structure on the bottom surface. Based on this DGS, the filter exhibits adjustable dual‐mode resonant characteristics under differential mode (DM) operation and widebandstop filtering characteristics under common‐mode (CM) operation. To verify the design concept, one filter to cover the UWB lower‐band has been designed, fabricated, and measured. The fabricated differential WBPF demonstrates a DM 3 dB fractional bandwidth of 59% with lower passband insertion loss of 0.52 dB, wider CM suppression better than 10 dB from DC to 11.5 GHz, and very compact size of 0.08
, where λg is the guided wavelength at the center frequency of the DM passband. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:1210–1213, 2015
Compact triple‐band bandpass filter using spilt ring resonator
Authors: Rathore Vaishali , Awasthi Seema , Biswas Animesh
Published: March 2015

Frequency transformation technique has been used for designing a six‐pole (3 × 2 pole) symmetrical triple‐band bandpass filter. Coupling matrix is obtained for filter specifications with 20‐dB return loss in the passbands, 500 MHz overall 3‐dB bandwidth, and 3‐GHz center frequency. Square split ring resonator (SRR) has been used for implementing the coupling matrix which provides miniaturization. Filter has been optimized using ADS circuit and ADS Momentum simulation for better results. Symmetrical triple‐band bandpass filter is fabricated and measured results show good agreement with ADS Momentum simulated response. Filter design using coupling matrix is less time consuming alternative when implemented using SRR as the range of coupling coefficients for particular bandwidth and center frequency can be calculated a prior and SRR aids in compact design and accurate tuning of the filter. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:1222–1225, 2015
Reduced field of view imaging using a static second‐order gradient for functional MRI applications
Authors: Islam Haisam , Glover Gary H.
Published: March 2015

Purpose

Imaging using reduced FOV excitation allows higher resolution or signal‐to‐noise ratio (SNR) per scan time but often requires long radiofrequency pulses. The goal of this study was to improve a recent reduced field of view (FOV) method that uses a second‐order shim gradient to decrease pulse length and evaluate its use in functional MRI (fMRI) applications.

Theory and Methods

The method, which was initially limited to excite thin disc‐shaped regions at the isocenter, was extended to excite thicker regions off the isocenter and produced accurate excitation profiles on a grid phantom. Visual stimulation fMRI scans were performed with full and reduced FOV. The resolution of the time series images and functional activation maps were assessed using the full‐width half‐maxima of the autocorrelation functions (FACFs) of the noise images and the activation map values, respectively.

Results

The resolution was higher in the reduced FOV time series images (4.1% ± 3.7% FACF reduction, P < 0.02) and functional activation maps (3.1% ± 3.4% FACF reduction, P < 0.01), but the SNR was lower (by 26.5% ± 16.9%). However, for a few subjects, the targeted region could not be localized to the reduced FOV due to the low Z2 gradient strength.

Conclusion

The results of this study suggest that the proposed method is feasible, though it would benefit from a stronger gradient coil. Magn Reson Med 75:817–822, 2016. © 2015 Wiley Periodicals, Inc.
Chinese Indentured Mine Labour and the Dangers Associated with Early 20th Century Deep‐level Mining on the Witwatersrand Gold Mines, South Africa
Authors: Meyer A. , Steyn M.
Published: March 2015

Trauma analysis in archaeological human remains can aid our understanding of cultural practices, socio‐economic status, environmental and social conditions, and even aspects of a person's occupation. For this reason, fracture patterns and frequencies can be useful in making inferences about the environment people lived and worked in. This is especially true for the 20th century mining industry where unskilled migrant labourers were often subjected to harsh working and living conditions. In this study, the skeletal remains of 36 Chinese indentured mine labourers, who worked and died on the Witwatersrand mines, South Africa, during the period ad 1904–1910, were assessed for evidence of trauma. Historical information suggests that these indentured Chinese labourers were unfamiliar with the workings of deep‐level mines and as a result sustained many work‐related injuries. Analyses suggest low frequencies of ante‐mortem trauma. In the few instances where they occurred, these healed fractures most probably reflect injuries already sustained in China, some time before Chinese indentured employment on the Witwatersrand mines. A high frequency of traumatic lesions, specifically peri‐mortem fractures, however, suggests a drastic shift in their working environment attesting to the hazardous working conditions associated with deep‐level mining in the early 20th century. Copyright © 2015 John Wiley & Sons, Ltd.
Transforming Relations of Gender, Person, and Agency in Oceania
Authors: Morgain Rachel , Taylor John P.
Published: March 2015

This introduction contextualises the nine papers that make up the special issueGender and Person in Oceania. Gender and personhood represent core orienting concepts within Pacific anthropology, from the pioneering work ofMarilynStrathern'sGender of the Giftto more recent scholarly attention to the impact ofChristianity and modernity. The papers in this volume offer a comparative and critical perspective on long‐standing ideas of ‘relational’ and ‘individual’ personhood across multiple sites inOceania, highlighting several key insights, including the importance of situated and relational understandings of agency and the centrality of those ‘things’ typically seen as non‐agentive to the formation of personhood. Most importantly, while re‐establishing the inseparable articulation of personhood with gendered dynamics, the contributors to this volume also highlight the differential, transforming, and shifting nature of engendered personhood, revealed through close attention to local knowledge, conditions, and practices.
Braed Praes in Vanuatu: Both Gifts and Commodities?
Authors: Jolly Margaret
Published: March 2015

The debate about braed praes as either gift or commodity has a long and complex genealogy in foreign writings on Oceania, engaging anthropologists, Christian missionaries, policy‐makers, and feminists. Debates between ni‐Vanuatu have been equally protracted, passionate, and complicated, creating an echo chamber of resounding conversations. Such debates and political contests about bride price address deep questions about the value of a woman – as a person, a worker, sexual partner, and mother – and engage profound philosophical questions about the local traction of imported distinctions between subjects and objects, persons and things, and how indigenous categories have been transformed by the longue durée of Christian conversions and simultaneous processes of commoditisation, complicit and conflictual. How have these transformed the ‘value’ of woman as bride and the character and significance of braed praes? Can the entrenched binaries in such debates be eclipsed by seeing braed praes as both gift and commodity?
‘Starting with a Prayer’: Women, Faith, and Security inFiji
Authors: George Nicole
Published: March 2015

Scholars of global security have recently been captured by the idea that there is a link between ‘sex and world peace’. They argue that the security of states and the international system should be understood as conditional upon the social, economic, and political standing of women. Accordingly, they contend that societies and states that display chauvinistic and discriminatory sociocultural influences are more tolerant of high levels of gender disadvantage and violence towards women, and more likely to be marked by general levels of belligerence, violence, and insecurity. Ideologies of faith are identified as helping to fuel this scenario. Hence, proponents of the ‘sex and world peace’ thesis construct a strongly oppositional relationship between gender and faith on the one hand, and gender and security on the other. In this paper, I challenge the idea that efforts to build security, gendered or otherwise, are only effective if they are secularised. I draw on examples from thePacific Islands to defend my case. While I concede that faith can be a source of insecurity in many parts of the Pacific Islands region, and is often invoked in ways that legitimise violence, I also discuss important examples that illustrate where and how faith is a resource for the region's women peacebuilders who have resisted violence in interpersonal, intercommunal, and interregional contexts.
The shared experience of adolescent and young adult cancer patients and their caregivers
Authors: Juth Vanessa , Silver Roxane Cohen , Sender Leonard
Published: March 2015

Objective

We examined the interdependent, dyadic, mental health of adolescent and young adult (AYA) cancer patients and their caregivers. Our aims were as follows: (1) to investigate the degree to which patients' and caregivers' subjective perceptions of illness severity are congruent with objective severity (i.e., medical indicators), (2) to compare patients' and caregivers' subjective perceptions of illness severity and cancer‐related posttraumatic stress symptoms (PTSS), and (3) to evaluate whether subjective perceptions of illness severity are linked to patients' and caregivers' cancer‐related PTSS.

Methods

The AYA cancer patients (n = 110; ages 12–24 years; 52% male) undergoing active treatment at an outpatient clinic and their caregivers (n = 110; 97% parents; ages 24–68 years; 89% female) independently reported their PTSS and subjective illness severity.

Results

Overall, neither patients' nor caregivers' reports of subjective illness severity were associated with objective illness severity. Caregivers reported higher PTSS than did patients and higher illness severity than younger, but not older, patients. Actor–partner interdependence model analyses indicated that AYA patients' subjective illness severity is the strongest predictor of their own PTSS and is a significant correlate of their caregivers' PTSS. Caregivers' subjective illness severity is associated with their own PTSS only. Results remained robust after controlling for demographic and illness characteristics.

Conclusions

The AYA patients' and caregivers' illness perceptions are distinct from each other and from objective medical indicators of illness severity. Patients' reports of subjective illness severity may be a marker for their own and their caregivers' mental health. Patient care and efficacious psychosocial interventions may require consideration of both patients' and caregivers' subjective perceptions of illness severity. Copyright © 2015 John Wiley & Sons, Ltd.
Synthesis of Few‐Layer Graphene‐on‐Insulator Films by Controllable C4F8 Plasma Etching SiC
Authors: Jin Chenggang , Huang Tianyuan , Yang Yan , Wu Mingzhi , Xu Yijun , Wu Zhaofeng , Zhuge Lanjian , Wu Xuemei , Ye Chao
Published: March 2015

C4F8‐based, inductively coupled plasma (ICP) combined with dual‐frequency capacitively coupled plasma (CCP) was used to etch 6H–SiC substrates for the synthesis of few‐layer graphene‐on‐insulator (FLGOI) films. The Raman spectroscopy studies were used to measure the thickness of the FLG samples. The combination of high frequency CCP and ICP modes can facilitate the tuning of the C4F8 discharge dissociation characteristics. A balance is struck between etching and deposition, leaving an ultra‐thin C‐rich overlaying film on the surface. After the layer is annealed at low temperature (920 °C), F atoms can be expelled leading to the reconstruction of the remainder material to form an FLG film. Considering the easy control of C4F8 plasma, our work opens up a new avenue for achieving FLGOI films with high yield at low temperature.
Comparison of Cylinder Data and Code Calculations for Homogeneous Explosives
Authors: Souers P.C. , Kury J.W.
Published: March 2015

Vergleich der Zylindertest‐Daten mit den Rechen‐Codes für homogene Explosivstoffe

Daten aus dem Kupferzylindertest von homogenen Explosivstoffen wurden gesammelt und verglichen mit den Relativ‐Volumina nahe 2, 4 und 7. Die Detonationsenergien, proportional zum Quadrat der Zylinderwandgeschwindigkeit, wurden bezogen auf hochverdichtetes PETN. Diese Energien werden verglichen mit JWL‐Werten, die abgeleitet wurden aus dem Hydrocode und aus den drei Codes für das Chemische Gleichgewicht: Tiger BKWR, Tiger JCZ3 und CHEQ. Die Werte des BKWR sind durchweg hoch, können aber korrigiert werden durch Eichung mit PETN. JCZ3 liefert die besten allumfassenden Energiewerte der 3 Modelle, obwohl diese durchweg hoch sind bei v, = 2. Die gesamte Detonationsenergie beim JWL‐Code liegt nahe der gemessenen Werte. Alles in allem ist die Qualität beim Fitten der thermochemischen Codes auf die aus den Zylinderwerten abgeleiteten Detonationsenergien schlecht und ein renormalisierter Code is dringend notwendig.
Impact Sensitivity Reduction Via Exo‐Electron Control
Authors: Rhein Robert A. , Reed Russell , Vu Ngo Q.
Published: March 2015

Reduzierung der Schlagempfindlichkeit über eine Kontrolle durch Exo‐Elektronen

Viele Materialien emittieren beim Bruch Elektronen (Exo‐Elektronen) in einem sogn. Frakto‐Emissionsprozeß. Bei Substanzen oder Mischungen, die deflagrieren oder detonieren können durch Stoß oder Reibung, können diese Exo‐Elektronen zur Initiierung der Deflagration oder Detonation beitragen. Einige Materialien, z.B. Halbleiter vom p‐Typ, können Exo‐Elektronen absorbieren und bei Verwendung als Additive die Stoß‐ oder Reibempfindlichkeit von Treibstoffen oder Sprengstoffen reduzieren. Es wurde gefunden, daß durch Zusatz von 1% Siliciumpulver vom p‐Typ die Schlagempfindlichkeit von Treibstoffen, die Ammoniumperchlorat in einer Polybutadien‐Matrix enthalten, abnimmt; die Schlagempfindlichkeit wird aber nicht vermindert bei HMX‐, RDX‐ und PETN‐Pulvern.
Numerical Determination of the Thermal Diffusivity and Kinetic Parameters of Solid Explosives
Authors: Roux M. , Marlin F. , Brassy C. , Gillard P.
Published: March 2015

Berechnung der Wärmeleitzahl und der kinetischen Parameter von explosiven Feststoffen

Die Wärmeleitzahl und die kinetischen Kennwerte (Aktivierungsenergie und präexponentieller Faktor) explosiver Substanzen wurden anhand einer digitalen und iterativen Methode bestimmt. Ein digitales Modell, auf einer Differenzenapproximation der nichtstationären Wärmetransportgleichung basierend, ermöglicht Simulationen des Wärmeverhaltens eines Produkts in Abwesenheit jeglicher Reaktion und jeglichen Phasenwechsels. Der Vergleich von Simulations‐ und Meßergebnissen erlaubt die Konvergenz zur Wärmeleitzahl der Testsubstanzen. Das angewendete Prinzip ist das gleiche wie für die kinetischen Kennwerte. In letzterem Fall berücksichtigt das Modell die Gleichung des nichtstationären Wärmeflusses mit einer inneren Energiequelle. Die partielle Differentialgleichung wird nach der Methode von Zinn und Mader behandelt.
Parameters Describing the Cylindrical Explosive Consolidation Technique
Authors: O'Donnell R.G.
Published: March 2015

Parameter zur Beschreibung der zylindrischen Verdichtungstechnik mit Explosivstoffen

Die Bedingungen, die erforderlich sind für eine erfolgreiche Herstellung von kompaktem Wolframpulver unter Einsatz der Explosivverdichtung, werden quantifiziert mit Hilfe einer Aufzeichnung der relativen Querschnittsbereiche des Explosivstoffs, des zylindrischen Containers und des Pulvers. Eine Testserie, die erlaubt die Verdichtungsbedingungen während des Tests zu variieren, stützt die Darstellung der Konsolidierungsbedingungen durch eine solche Aufzeichnung. Es wurde beobachtet, daß die Kompaktdichte von der Teilchengröße des Pulvers abhängt. Es wird angenonmen, daß die niedrigere Dichte bei kompaktierten Pulvern mit großer Teilgröße bei gleichen Verdichtungsbedingungen durch eine geringere Verdichtungsfähigkeit dieser größeren Partikel verursacht wird.
Analysis of differential secondary effects of novel rexinoids: select rexinoid X receptor ligands demonstrate differentiated side effect profiles
Authors: Marshall Pamela A. , Jurutka Peter W. , Wagner Carl E. , van der Vaart Arjan , Kaneko Ichiro , Chavez Pedro I. , Ma Ning , Bhogal Jaskaran S. , Shahani Pritika , Swierski Johnathon C. , MacNeill Mairi
Published: March 2015

In order to determine the feasibility of utilizing novel rexinoids for chemotherapeutics and as potential treatments for neurological conditions, we undertook an assessment of the side effect profile of select rexinoid X receptor (RXR) analogs that we reported previously. We assessed pharmacokinetic profiles, lipid and thyroid‐stimulating hormone (TSH) levels in rats, and cell culture activity of rexinoids in sterol regulatory element‐binding protein (SREBP) induction and thyroid hormone inhibition assays. We also performed RNA sequencing of the brain tissues of rats that had been dosed with the compounds. We show here for the first time that potent rexinoid activity can be uncoupled from drastic lipid changes and thyroid axis variations, and we propose that rexinoids can be developed with improved side effect profiles than the parent compound, bexarotene (1).
Incorporation of concentration data below the limit of quantification in population pharmacokinetic analyses
Authors: Keizer Ron J. , Jansen Robert S. , Rosing Hilde , Thijssen Bas , Beijnen Jos H. , Schellens Jan H. M. , Huitema Alwin D. R.
Published: March 2015

Handling of data below the lower limit of quantification (LLOQ), below the limit of quantification (BLOQ) in population pharmacokinetic (PopPK) analyses is important for reducing bias and imprecision in parameter estimation. We aimed to evaluate whether using the concentration data below the LLOQ has superior performance over several established methods. The performance of this approach (“All data”) was evaluated and compared to other methods: “Discard,” “LLOQ/2,” and “LIKE” (likelihood‐based). An analytical and residual error model was constructed on the basis of in‐house analytical method validations and analyses from literature, with additional included variability to account for model misspecification. Simulation analyses were performed for various levels of BLOQ, several structural PopPK models, and additional influences. Performance was evaluated by relative root mean squared error (RMSE), and run success for the various BLOQ approaches. Performance was also evaluated for a real PopPK data set. For all PopPK models and levels of censoring, RMSE values were lowest using “All data.” Performance of the “LIKE” method was better than the “LLOQ/2” or “Discard” method. Differences between all methods were small at the lowest level of BLOQ censoring. “LIKE” method resulted in low successful minimization (<50%) and covariance step success (<30%), although estimates were obtained in most runs (~90%). For the real PK data set (7.4% BLOQ), similar parameter estimates were obtained using all methods. Incorporation of BLOQ concentrations showed superior performance in terms of bias and precision over established BLOQ methods, and shown to be feasible in a real PopPK analysis.
Tandem mass spectrometry and density functional theory of RDX fragmentation pathways: Role of ion–molecule complexes in loss of NO3 and lack of molecular ion peak
Authors: Jeilani Yassin A. , Duncan Kameron A. , Newallo Domnique S. , Thompson Albert N. , Bose Nripendra K.
Published: March 2015

Rationale

Hexahydro‐1,3,5‐trinitro‐1,3,5‐triazine (RDX) is an explosive compound that finds a wide range of military and civilian applications. RDX has been a target in environmental matrices by gas chromatography/tandem mass spectrometry (GC/MS/MS). MS/MS in negative chemical ionization (NCI) mode of RDX provides important fragmentation patterns that are useful for structural elucidation. The fragmentation patterns are needed for proper identification of precursor and product ions in analytical methods that depend on MS/MS approaches for a reliable identification of RDX.

Methods

This study focuses on the MS fragmentation mechanisms of RDX in NCI mode using both MS/MS and density functional theory (DFT). The DFT studies were performed at the B3LYP/6‐311G(d,p) level of theory.

Results

The DFT results showed that NCI of RDX leads to the formation of an anion–molecule complex that was energetically more stable than the RDX anion. The fragmentation proceeds through two pathways, leading to the loss of NO2 and NO3. The loss of NO3 takes place in an anion–molecule complex leading to the formation of characteristic nitroso group fragment ions. Using the fragmentation schemes, important ion structures are proposed including structures for m/z 160, 129, 102, and 86.

Conclusions

The results demonstrate the importance of both charge‐induced and charge‐remote dissociations in RDX pathways. The ion structures identified along the pathways could be used as targets in analytical methods for reliable identification purposes. Copyright © 2015 John Wiley & Sons, Ltd.
Robust attitude tracking control of spacecraft under control input magnitude and rate saturations
Authors: Zou An‐Min , Kumar Krishna Dev , de Ruiter Anton H. J.
Published: March 2015

This paper investigates the problem of attitude tracking control of spacecraft subject to control input magnitude and rate saturations. The smooth hyperbolic tangent function is used to model the magnitude and rate saturations. As the system is non‐affine in the control input, an augmented plant is presented to facilitate the development of the control law. The backstepping technique, robust control and adaptive control approaches are applied to design the control law. The stability of the closed‐loop system is guaranteed by the Lyapunov method. Numerical simulations are presented to demonstrate the performance of the proposed controller. Copyright © 2015 John Wiley & Sons, Ltd.
A Bayesian framework to account for uncertainty due to missing binary outcome data in pairwise meta‐analysis
Authors: Turner N. L. , Dias S. , Ades A. E. , Welton N. J.
Published: March 2015

Missing outcome data are a common threat to the validity of the results from randomised controlled trials (RCTs), which, if not analysed appropriately, can lead to misleading treatment effect estimates. Studies with missing outcome data also threaten the validity of any meta‐analysis that includes them. A conceptually simple Bayesian framework is proposed, to account for uncertainty due to missing binary outcome data in meta‐analysis. A pattern‐mixture model is fitted, which allows the incorporation of prior information on a parameter describing the missingness mechanism. We describe several alternative parameterisations, with the simplest being a prior on the probability of an event in the missing individuals. We describe a series of structural assumptions that can be made concerning the missingness parameters. We use some artificial data scenarios to demonstrate the ability of the model to produce a bias‐adjusted estimate of treatment effect that accounts for uncertainty. A meta‐analysis of haloperidol versus placebo for schizophrenia is used to illustrate the model. We end with a discussion of elicitation of priors, issues with poor reporting and potential extensions of the framework. Our framework allows one to make the best use of evidence produced from RCTs with missing outcome data in a meta‐analysis, accounts for any uncertainty induced by missing data and fits easily into a wider evidence synthesis framework for medical decision making. © 2015 The Authors. Statistics in MedicinePublished by John Wiley & Sons Ltd.
A practical design for a dual‐agent dose‐escalation trial that incorporates pharmacokinetic data
Authors: Cotterill Amy , Lorand Daniel , Wang Jixian , Jaki Thomas
Published: March 2015

Traditionally, model‐based dose‐escalation trial designs recommend a dose for escalation based on an assumed dose‐toxicity relationship. Pharmacokinetic data are often available but are currently only utilised by clinical teams in a subjective manner to aid decision making if the dose‐toxicity model recommendation is felt to be too high. Formal incorporation of pharmacokinetic data in dose‐escalation could therefore make the decision process more efficient and lead to an increase in the precision of the resulting recommended dose, as well as decreasing the subjectivity of its use. Such an approach is investigated in the dual‐agent setting using a Bayesian design, where historical single‐agent data are available to advise the use of pharmacokinetic data in the dual‐agent setting. The dose‐toxicity and dose‐exposure relationships are modelled independently and the outputs combined in the escalation rules. Implementation of stopping rules highlight the practicality of the design. This is demonstrated through an example which is evaluated using simulation. Copyright © 2015 John Wiley & Sons, Ltd.
Hypothesis testing for two‐stage designs with over or under enrollment
Authors: Zeng Donglin , Gao Fei , Hu Kuolung , Jia Catherine , Ibrahim Joseph G.
Published: March 2015

Simon's two‐stage designs are widely used in cancer phase II clinical trials for assessing the efficacy of a new treatment. However in practice, the actual sample size for the second stage is often different from the planned sample size, and the original inference procedure is no longer valid. Previous work on this problem has certain limitations in computation. In this paper, we attempt to maximize the unconditional power while controlling for the type I error for the modified second stage sample size. A normal approximation is used for computing the power, and the numerical results show that the approximation is accurate even under small sample sizes. The corresponding confidence intervals for the response rate are constructed by inverting the hypothesis test, and they have reasonable coverage while preserving the type I error. Copyright © 2015 John Wiley & Sons, Ltd.
High‐Performance Sb/Sb2O3 Anode Materials Using a Polypyrrole Nanowire Network for Na‐Ion Batteries
Authors: Nam Do‐Hwan , Hong Kyung‐Sik , Lim Sung‐Jin , Kim Min‐Joong , Kwon Hyuk‐Sang
Published: March 2015

Three‐dimensional porous Sb/Sb2O3 anode materials are successfully fabricated using a simple electrodeposition method with a polypyrrole nanowire network. The Sb/Sb2O3–PPy electrode exhibits excellent cycle performance and outstanding rate capabilities; the charge capacity is sustained at 512.01 mAh g−1 over 100 cycles, and 56.7% of the charge capacity at a current density of 66 mA g−1 is retained at 3300 mA g−1. The improved electrochemical performance of the Sb/Sb2O3–PPy electrode is attributed not only to the use of a highly porous polypyrrole nanowire network as a substrate but also to the buffer effects of the Sb2O3 matrix on the volume expansion of Sb. Ex situ scanning electron microscopy observation confirms that the Sb/Sb2O3–PPy electrode sustains a strong bond between the nanodeposits and polypyrrole nanowires even after 100 cycles, which maintains good electrical contact of Sb/Sb2O3 with the current collector without loss of the active materials.
A parallel and efficient approach to large scale clone detection
Authors: Sajnani Hitesh , Saini Vaibhav , Lopes Cristina
Published: March 2015

We propose a new token‐based approach for large ‐scale code clone detection, which is based on a filtering heuristic that reduces the number of token comparisons when the two code blocks are compared. We also present a MapReduce based parallel algorithm that uses the filtering heuristic and scales to thousands of projects. The filtering heuristic is generic and can also be used in conjunction with other token‐based approaches. In that context, we demonstrate how it can increase the retrieval speed and decrease the memory usage of the index‐based approaches. In our experiments on 36 open source Java projects, we found that: (i) filtering reduces token comparisons by a factor of 10, and thus increasing the speed of clone detection by a factor of 1.5; (ii) the speed‐up and scale‐up of the parallel approach using filtering is near‐linear on a cluster of 2–32 nodes for 150–2800 projects; and (iii) filtering decreases the memory usage of index‐based approach by half and the search time by a factor of 5. Copyright © 2015 John Wiley & Sons, Ltd.
Perineal and vaginal tears are clinical markers for occult levator ani trauma: a retrospective observational study
Authors: Shek K. L. , Green K. , Hall J. , Guzman‐Rojas R. , Dietz H. P.
Published: March 2015

Objectives

Levator avulsion has been shown to be associated with anterior and central compartment prolapse and is a risk factor for prolapse recurrence. Diagnosis in the delivery room is usually impossible, as levator avulsion is commonly occult. The objective of this study was to determine if vaginal and major perineal tears are clinical markers of levator trauma as diagnosed by four‐dimensional (4D) translabial ultrasound 3–6 months postpartum.

Methods

This was a retrospective observational study using data obtained in two perinatal trials. A total of 774 women seen, on average, 5 (range, 2.3–22.4) months after their first delivery of a term singleton cephalic baby underwent a standardized interview, clinical assessment and 4D translabial ultrasound examination. Clinical data were obtained from the institutional obstetric database, including information on vaginal and perineal tears. Levator avulsion was diagnosed using tomographic ultrasound, with operators blinded to the clinical data.

Results

Both third‐ and fourth‐degree perineal tears and vaginal sidewall tears were independently associated with levator avulsion (P = 0.004 and P = 0.012, respectively). The odds ratio for avulsion in women suffering from such overt trauma was 3.44 (95% CI, 1.47–8.03) for third‐/fourth‐degree perineal tears and 3.35 (95% CI, 1.30–8.61) for vaginal sidewall tears.

Conclusions

Vaginal sidewall and third‐/fourth‐degree perineal tears were found to be independent clinical indicators of an increased risk of levator trauma, as diagnosed by 4D translabial ultrasound 3–6 months postpartum. Such clinical markers may become useful in the identification of women at high risk of levator trauma and future pelvic floor disorders. Copyright © 2015 ISUOG. Published by John Wiley & Sons Ltd.
Mechanisms of plant cell division
Authors: Lipka Elisabeth , Herrmann Arvid , Mueller Sabine
Published: March 2015

Plant cells are confined by a network of cellulosic walls that imposes rigid control over the selection of division plane orientations, crucial for morphogenesis and genetically regulated. While in animal cells and yeast, the actin cytoskeleton is instrumental in the execution of cytokinesis, in plant cells the microtubule cytoskeleton is taking the lead in spatially controlling and executing cytokinesis by the formation of two unique, plant‐specific arrays, the preprophase band (PPB) and the phragmoplast. The formation of microtubule arrays in plant cells is contingent on acentrosomal microtubule nucleation. At the onset of mitosis, the PPB defines the plane of cell division where the partitioning cell wall is later constructed by the cytokinetic phragmoplast, imposing a spatio‐temporal relationship between the two processes. Current research progress in the field of plant cell division focuses on identifying and tying the links between early and late events in spatial control of cytokinesis and how microtubule array formation is regulated in plant cells. WIREs Dev Biol 2015, 4:391–405. doi: 10.1002/wdev.186

This article is categorized under:

Plant Development > Vegetative Development
High False Positivity in Positron Emission Tomography is a Potential Diagnostic Pitfall in Patients with Suspected Adrenal Metastasis
Authors: Lang Brian Hung‐Hin , Cowling Benjamin J. , Li Jason Yu‐Yin , Wong Kai Pun , Wan Koon Yat
Published: March 2015

Background

Although 18F‐fluorodeoxyglucose (FDG) positron emission tomography combined with computed tomography (PET/CT) is a potentially powerful, non‐invasive imaging tool in differentiating adrenal metastasis from benign disease, some adenomas also exhibit high FDG uptake, therefore mimicking metastasis (i.e., false positives). We aimed to evaluate the accuracy of FDG‐PET/CT based exclusively on histology and to identify risk factors for adrenal metastasis.

Methods

Among the 289 consecutive patients who underwent adrenalectomy, 39 (78.0 %) patients had suspected solitary adrenal metastasis and had a positive preoperative FDG‐PET/CT. The FDG‐PET/CT findings were correlated with the histology of the excised adrenal gland. To identify risk factors for adrenal metastasis, characteristics were compared between patients with histologically proven adrenal metastasis and those without. Youden’s index was used to calculate the optimal cut‐off value for predicting adrenal metastasis.

Results

Histology of the excised adrenal tumor confirmed adrenal metastasis in 28/39 (71.8 %) patients while non‐metastatic lesions comprised mostly benign adrenal cortical adenoma (n = 10) and one non‐functional pheochromocytoma. Therefore, the overall false‐positive rate of FDG‐PET/CT was 28.2 %. History of primary lung malignancy [odds ratio (OR) (95 % CI) 20.00 (1.01–333.3), p = 0.049] and SUVmax > 2.65 [OR (95 % CI) 31.606 (2.46–405.71), p = 0.008] were independent risk factors for adrenal metastasis.

Conclusions

Single adrenal uptake on FDG‐PET/CT in suspected solitary adrenal metastasis was associated with a high false‐positive rate (28.2 %). Risk factors associated with adrenal metastasis included a history of known primary lung malignancy and a SUVmax > 2.65 at the adrenal lesion of interest on FDG‐PET/CT. Based on these findings, a new algorithm was constructed.
Validation and Comparison of Nomograms in Predicting Disease‐Specific Survival for Papillary Thyroid Carcinoma
Authors: Lang Brian Hung‐Hin , Wong Carlos K. H.
Published: March 2015

Background

Nomogram could estimate individualized prognosis in papillary thyroid carcinoma (PTC). We aimed to create and validate a new nomogram and compare it with other published nomograms using a large patient cohort.

Methods

Eight‐hundred and forty‐nine PTC patients with ≥7 years follow‐up were randomly assigned to the development (n = 425)
and validation (n = 424) groups. The former was used for developing a nomogram for disease‐specific survival (DSS), while the latter was for validating the nomogram by discrimination [or area under curve (AUC)]. AUC of the newly developed nomogram was compared to other published nomograms.

Results

The 5‐ and 10‐year risk of dying from PTC were 1.4 and 3.3 %, respectively, while dying from non‐PTC‐related causes were 2.3 and 5.1 %, respectively. The new nomogram was developed from age, tumor size, multifocality, nodal status and distant metastases. The discrimination was excellent (AUC (95 % CI) for 5‐ and 10‐year DSS were 0.896 (0.683–0.971) and 0.919 (0.871–0.967), respectively). Its predictability was similar to other published nomograms (p > 0.05). Based on the new nomogram, a total score of <28 meant 99.72 % chance of surviving from PTC at 10 years while a score of ≥28 meant 9.09 % chance of dying from PTC at 10 years.

Conclusions

Using variables from the current tumor node metastasis (TNM) staging system, a new nomogram was developed. It exhibited excellent discriminatory ability and accuracy in predicting 10‐year DSS relative to other published nomograms. However, given the excellent prognosis of PTC, the new nomogram was better at ruling out than predicting PTC‐related death. Further validation by an external cohort is required.