bluuebunny/crossref_metadata_2025 huggingface dataset:
Rural Households' Demand for Frankincense Forest Conservation in Tigray, Ethiopia: A Contingent Valuation Analysis
Authors: Tilahun M. , Vranken L. , Muys B. , Deckers J. , Gebregziabher K. , Gebrehiwot K. , Bauer H. , Mathijs E.
Published: March 2013

Frankincense from Boswellia papyrifera forest (BPF) is a traded commodity used in the pharmaceutical, food, cosmetic and chemical industries. Ethiopia is an important producer of frankincense, but the resource is under continuous degradation and requires conservation. We applied a contingent valuation to assess rural households' willingness to pay and willingness to contribute labor for BPF conservation. Next to the bid, willingness to pay is influenced most by income, education, and willingness to contribute labor by family labor and gender of the household head. A household is willing to pay at least $4·86 or contribute 7·17 labor days per year, which amounts to $6·64 at per capita daily income. This suggests that using per capita daily income rather than market wage rates could result in convergence in response asymmetry of labor and cash payment vehicles. The potential local demand for conservation of BPF could be mobilized effectively with complementary policy interventions aimed at sustainable use and poverty reduction. Copyright © 2013 John Wiley & Sons, Ltd.
Serum alpha-fetoprotein level independently predicts posttransplant survival in patients with hepatocellular carcinoma
Authors: Berry Kristin , Ioannou George N.
Published: March 2013

We aimed to determine whether combining serum alpha-fetoprotein (AFP) level with hepatocellular carcinoma (HCC) tumor burden would allow better stratification of posttransplant survival for patients with HCC undergoing liver transplantation. Adjusting for donor and recipient characteristics, we calculated the risk of posttransplant mortality associated with serum AFP level or HCC tumor burden for all first-time adult liver transplants performed in the United States between 2002 and 2011 (n = 45,267). Serum AFP level, rather than tumor burden, was the tumor characteristic most strongly associated with posttransplant survival. Although recipients with HCC and a serum AFP level ≤ 15 ng/mL at the time of transplantation had no excess posttransplant mortality [adjusted hazard ratio (AHR) = 1.02, 95% confidence interval (CI) = 0.93-1.12], patients with a serum AFP level of 16 to 65 ng/mL (AHR = 1.38, 95% CI = 1.23-1.54), patients with a serum AFP level of 66 to 320 ng/mL (AHR = 1.65, 95% CI = 1.45-1.88), and patients with a serum AFP level > 320 ng/mL (AHR = 2.37, 95% CI = 2.06-2.73) had progressively worse posttransplant mortality in comparison with recipients without HCC. Patients with a tumor burden exceeding the Milan criteria (who are usually excluded from transplantation) had excellent posttransplant survival if their serum AFP level was 0 to 15 ng/mL (AHR = 0.97, 95% CI = 0.66-1.43). In contrast, patients within the Milan criteria (who are routinely considered to be transplant candidates) had poor survival if their serum AFP level was substantially elevated (for a serum AFP level ≥ 66 ng/mL, AHR = 1.93, 95% CI = 1.74-2.15). Changes in serum AFP level while patients were on the waiting list corresponded closely to changes in posttransplant mortality. In conclusion, the absolute serum AFP level and changes in the serum AFP level strongly predict posttransplant survival independently of the tumor burden. We hope that these data, in combination with other factors, can be used to inform future studies and ongoing discussions aimed at improving the eligibility criteria for liver transplantation for patients with HCC. Liver Transpl 19:634–645, 2013. © 2013 AASLD.
Stability and integrability of horizontally conformal maps and harmonic morphisms
Authors: Kim J.‐J. , Yun G.
Published: March 2013

In this article, we study stability of minimal fibers and integrability of horizontal distribution for horizontally conformal maps and harmonic morphisms. Let be a horizontally conformal submersion. We prove that if the horizontal distribution is integrable, then any minimal fiber of φ is volume‐stable. This result is an improved version of the main theorem in [15]. As a corollary, we obtain if φ is a submersive harmonic morphism whose fibers are totally geodesic, and the horizontal distribution is integrable, then any fiber of φ is volume‐stable and so such a map φ is energy‐stable if M is compact. We also show that if is a horizontally conformal map from a compact Riemannian manifold M into an orientable Riemannian manifold N which is horizontally homothetic, and if the pull‐back of the volume form of N is harmonic, then the horizontal distribution is integrable and φ is a harmonic morphism.
Plasma urate in REM sleep behavior disorder
Authors: Martín Reinaldo Uribe‐San , Francke Pablo Venegas , Illanes Felipe López , Gazmuri Alex Jones , Rivera Julio Salazar , Ferńndez Jaime Godoy , Martínez Julia Santín , Juri Carlos
Published: March 2013

Background

Rapid eye movement (REM) sleep behavior disorder (RBD) is associated with a high risk of developing Parkinson's disease (PD). Higher urate levels are associated with a lower risk of PD. We conducted a study to evaluate plasma urate levels in patients with RBD and their role in the development of PD.

Methods

We evaluated plasma urate levels in a cohort of 24 patients with idiopathic RBD. Patients were divided into 2 groups according to the presence or absence of PD. Other known markers of the risk of developing PD, such as olfaction testing, and substantia nigra (SN) hyperechogenicity, were evaluated in the 2 groups.

Results

No differences were observed regarding age, years of evolution of the RBD, SN hyperechogenicity, or plasma urate levels between the 2 groups. In patients without PD, there was a positive correlation between years of evolution of RBD and the levels of uric acid (R2 = 0.88). Patients without PD and those who had more than 5 years of RBD exhibited higher levels of uric acid than patients with PD (P = 0.02).

Conclusions

Higher levels of plasma urate were associated with a longer duration of RBD without converting to PD. Future prospective studies would be needed to confirm this finding. Disorder Society.© 2013 Movement Disorder Society
A novel compact multi‐band microstrip antenna with multiple narrow slits
Authors: Verma Sapna , Ansari Jamshed A. , Verma M. K.
Published: March 2013

In this article, a novel multi‐band microstrip antenna is designed and fabricated. The design antenna can excite four operating bands by the multiple slits embedded on a rectangular patch having dimensions 26×37.5 mm2. The operating bands centered at 5.875, 6.19, 6.96, and 7.87 GHz, which meets the design specification of covering the WLAN/WiMAX and C‐bands. The radiation pattern and gain of the proposed antenna are presented at various frequencies. A good agreement between simulated and measured results is obtained. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:1196–1198, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27537
Application of the protruded strip structures to design an ultra‐wideband slot antenna with variable frequency band‐stop function
Authors: Ojaroudi Nasser , Ojaroudi Mohammad
Published: March 2013

A novel method for designing a new slot antenna with band‐notched characteristic for ultra wide‐band (UWB) applications has been presented in this article. The proposed antenna consists of slotted ground plane with an extra rectangular slot with a pair of L‐shaped strips protruded inside the slot, and a square ring radiating stub with a pair of T‐shaped protruded strips inside the square ring. By cutting an extra rectangular slot with a pair of L‐shaped protruded strips in the ground plane, additional resonance is excited and hence much wider impedance bandwidth can be produced, especially at the higher band that the antenna provides a wide usable fractional bandwidth of more than 125% (3.08–14.13 GHz). In order to generate a band‐notched characteristic, we use the square ring stub with a pair of T‐shaped strips protruded inside the square ring. The measured results reveal that the presented slot antenna offers a very wide bandwidth with band‐notched operation, covering the WLAN band (5.12–6.05 GHz). The designed antenna has a small size of 20 × 20 mm2. Good return loss and radiation pattern characteristics are obtained in the frequency band of interest. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:1312–1316, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27540
Identification of the intrinsic capacitive core for GaAs HEMTs by investigating the frequency behavior of the impedance parameters
Authors: Crupi Giovanni , Raffo Antonio , Schreurs Dominique M.M.‐P. , Avolio Gustavo , Caddemi Alina , Vannini Giorgio
Published: March 2013

The present study is focused on the analysis of the impact of the dips in the impedance parameters on the behavior of the hybrid parameters for scaled GaAs HEMTs. These dips turning into kink phenomena in the magnitude of the hybrid parameters consist of a sudden reduction of the magnitude of the impedance parameters at a given value of the frequency, due to the transition from a capacitive to an inductive behavior. A theoretical and experimental investigation is developed for determining the resonance frequency associated to such dips in terms of the equivalent circuit elements. The achieved formulas are exploited to propose a novel approach for the identification of the intrinsic capacitive core. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:1237–1240, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27544
A new hybrid‐polymer optically tunable dielectric and its measurement using a variation on the split‐post dielectrc resonator
Authors: Jess Nathan , Syrett Barry , McGarry Steve , Roy Langis
Published: March 2013

An apparatus based on the split‐post dielectric resonator was designed and verified for the purpose of measuring the microwave properties of optically sensitive materials.The apparatus was then used to confirm that a material consisting of micro sized photoconductive particles added to an insulating polymer would show an increase in the effective dielectric constant while under optical illumination. The semiconductor‐polymer composite showed a change in dielectric constant and dielectric loss tangent from 5.5 to 6.1 and 0.05 to 0.09 respectively. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:1304–1305, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27545
Compact and high performance microstrip diplexer for GPS and WLAN application
Authors: Deng Hong‐wei , Zhao Yong‐jiu , Fu Yong , Zhou Xiao‐jun , Liu Yan‐yun
Published: March 2013

In this article, a novel compact and high performance microstrip diplexer is designed for global position system (GPS) and wireless local area network (WLAN) applications. The compact diplexer consists of two filters with short centered stepped impedance resonators (SCSIRs) and quarter‐wavelength resonators (QWRs), operated at 1.575 GHz and 5.8 GHz, respectively. Due to the intrinsic characteristics and mutual loading effect of two filters, multiple transmission zeros can be generated to achieve sharp skirt, wide stopband, and high isolation of the diplexer. Moreover, more compact size can be obtained without the extra junction matching. Finally, a microstrip diplexer with 1 dB absolute bandwidth 100 MHz for GPS channel and 1 dB fractional bandwidth (FBW) of 3.45% at 5.8 GHz for WLAN channel is designed and fabricated. The simulated and measured results show a better agreement and validate the proposed theory. The size without the 50 Ω feedline is only 0.156 λg × 0.103λg, in which λg is the guided wavelength at 1.575 GHz. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:1233–1237, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27550
On the isolation of two LTE700/2300/2500 antennas in the laptop computer
Authors: Wong Kin‐Lu , Lin Po‐Wei , Wu Tsung‐Ju
Published: March 2013

A simple technique for achieving enhanced isolation between two long‐term evolution (LTE)700/2300/2500 antennas for the multiple‐input multiple‐output operation in the laptop computer is presented.The two antennas are mounted along the top edge of the supporting metal plate, which is generally disposed on the inner surface of the upper cover of the laptop computer. Improved isolation (measured S21 better than −30 dB in the LTE700 band and −26 dB in the LTE2300/2500 bands) between the two antennas is easily achieved by adjusting the supporting metal plate to have a length of about 110 mm in the longitudinal direction (orthogonal to the lateral direction or the top‐edge direction of the supporting metal plate). Because the length is close to a quarter wavelength of a frequency in the LTE700 band, the excited surface currents in the supporting metal plate will become stronger in the longitudinal direction, which hence causes weaker surface currents flowing along the top edge of the supporting metal plate. This behavior leads to enhanced isolation between the antennas mounted along the top edge of the supporting metal plate. Details of the proposed isolation technique are described, and the obtained results are presented and discussed. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:1370–1375, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27555
All‐optical binary‐to‐octal encoder based on a semiconductor optical amplifier: Application to eight‐level amplitude‐shift keying signaling
Authors: Cortés Obed Pérez , Ortiz Horacio Soto , Valdez Juan Carlos Domínguez
Published: March 2013

An all‐optical encoder performing a binary to octal amplitude shift keying conversion based on cross‐polarization modulation and cross‐gain modulation in a semiconductor optical amplifier is presented. The encoder is experimentally demonstrated by making, in a separated signal of different wavelength, an eight‐level ASK signaling of three parallel binary waveforms. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:1316–1321, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27559
Switchable photonic‐crystal‐grating diode using coherent atomic gas
Authors: Serebryannikov Andriy E. , Lakhtakia Akhlesh
Published: March 2013

Asymmetry in a regular dielectric photonic crystal of finite thickness created by periodically altering one of its two pupils results in the exhibition of diode‐like passbands that can be switched on/off by injecting/removing a coherent atomic gas.The diode‐like operation is accompanied by diffraction‐enabled deflection of the transmitted wave, within a stop band of the gas‐free structure. Alteration of the oscillator strength can be used to engineer the passband characteristics. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:1248–1250, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27562
Multiple mode resonance BPF design using suspended stripline with source‐load coupling structure
Authors: Ho Min‐Hua , Hong Wanchu , Lin Hong‐Yin , Chen Po‐Fan
Published: March 2013

A multiple‐mode resonance bandpass filter of suspended stripline structure is proposed in this article with a source‐load coupling feed design. Equivalent quasilumped elements circuit model is developed to represent the proposed filter's discontinuities and to emulate its frequency responses. The odd‐ and even‐mode equivalent half circuits extracted from the derived LC circuit model are also examined for analyzing the circuit's mode resonances. Multiple resonances, which relate to two odd modes and two even modes, are observed. The circuit's physical layout of the proposed filter is guided by the LC circuits, and then the circuit's dimensions are optimized by sonnet simulation. Experiment is conducted to verify the filter's performance and agreements between the simulations and the measurements are observed. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:1382–1385, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27565
A miniaturized dual‐band antenna for long‐term evolution system template
Authors: Lin Chih Peng , Lin T.Y. , Huang Jie‐Huang , Jou Christina F.
Published: March 2013

Long‐term evolution (LTE) (fourth generation mobile networks) has utilized multiple‐input–multiple output (MIMO) technology to achieve very high data rates in both uplink and downlink. MIMO is based on the multiple antenna systems within the small size mobile terminal. One of the challenges is to miniaturize the mobile terminal. In this article, a compact antenna with the dual‐band characteristics, which meet the specification of the LTE frequency band (680–900 MHz and 2.28–2.82 GHz) is proposed. The bandwidths of both the lower and the higher frequency bands are 320 and 540 MHz, respectively. The total size of the antenna is 54 × 26.6 mm2. A fairly good agreement has been shown between the simulation and experimental results. The study on the effect of the various antenna parameters has also been discussed. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:1379–1382, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27566
Dual‐polarized multiband frequency selective surface with miniaturized hilbert element
Authors: Lv Yuan‐Yuan , Chen Wen‐Ling
Published: March 2013

A novel Hilbert frequency selective surface (FSS) is proposed and experimental studied. By etching the FSS elements as two iteration Hilbert curve and arraying the Hilbert FSS elements symmetrically, it is experimentally found that the proposed FSS is dual‐polarized, and several stopbands are exhibited within the operating frequency band. It is also observed that the proposed Hilbert FSS element achieved a size reduction of 93.6% when compared to the conventional square patch FSS resonated at the similar frequency. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:1221–1223, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27570
Low power saw‐less WCDMA transmitter with quadrature driver amplifier and injection‐locked frequency divider
Authors: Jiang Peichen , Guan Rui , Zhou Jianjun
Published: March 2013

A direct conversion transmitter with low noise and low power is presented in this article.A quadrature driver amplifier is used to remove the Inphase‐Quadrature crosstalk in a passive mixer operating with 50% duty cycle local oscillator (LO). In the quadrature LO generation, an inductor‐less injection‐locked frequency divider is utilized to reduce the phase noise contribution with cost of a small current and area. Fabricated in 65 nm CMOS process, a transmitter prototype is designed for wideband code division multiple access (WCDMA) application. Measurement results show that the proposed transmitter achieves 1 dBm maximum output power at 2.53 GHz, 1.7% error vector magnitude (EVM), and −158.5 dBc/Hz output noise at the receiver (RX) band, eliminating the need for the surface acoustic wave (SAW) filter in a traditional transmitter design, with an area of 0.18 mm2 and a total power consumption of 37.8 mW. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:1217–1221, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27571
Investigation on ZPT ceramics applied as dielectric resonator antenna for ultra wideband systems
Authors: de Medeiros J. L. G. , de Araújo W.C. , d'Assunção A. G. , de Mendonça L. M. , de Oliveira J. B. L.
Published: March 2013

This article presents an investigation about dielectric resonator antennas. The configuration of antenna is reported using an new structure cylindrical in the shape of disc dielectric, which has its molar representation given by Zn0,8Pb0,2TiO3 (ZPT) stacked vertically about a ground plane and excited by a coaxial probe. The process of construction and characterization of the dielectric resonator are presented. The numerical procedure is performed through of the HFSS commercial software based in the finite‐element method. An excellent agreement between theoretical and experimental results is observed. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:1352–1355, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27576
Three‐stage doherty amplifier with uneven input splitter
Authors: Seo M. , Song M. , Gu J. , Kim H. , Ham J. , Park C. , Yang Youngoo
Published: March 2013

This article presents a new high‐efficiency three‐stage Doherty power amplifier (DPA) using a simple uneven power splitter. The proposed three‐way uneven power splitter, which was designed based on a multiway Wilkinson power divider, was applied to the three‐stage DPA. Also, the proposed structure is much simpler and uses fewer lumped components than the conventional one. Using the uneven input splitter, each individual amplifier in the DPA has an appropriate input power level. It results in a proper load modulation of the three‐stage Doherty amplifier. The proposed three‐stage DPA has been implemented for the E‐UTRA‐13 band of from 746 to 756 MHz. For the LTE‐frequency‐division duplexing release 9 downlink signal with a peak‐to‐average power ratio of 10 dB and a signal bandwidth of 5 MHz, a high power‐added efficiency of 42.3% and an adjacent channel leakage power ratio of −37 dBc at an offset of 2.7 MHz were experimentally achieved at an average output power of 30 dBm. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:1405–1409, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27581
Hybrid dielectric resonator integrated pyramidal horn antenna
Authors: Ain Mohd Fadzil , Othman Ali , Ahmad Zainal Arifin
Published: March 2013

This article presents the design, simulation, and fabrication of hybrid dielectric resonator integrated pyramidal horn antenna (HDRIPHA) operating from frequency range of 10–18 GHz to cover most of the existing Ku‐band microwave frequencies. The designed HDRIPHA is analyzed and optimized using power modeling software CST Microwave Studio ®. The designed HDRIPHA assembly consists of hybridizing a circular sector dielectric resonator (DR) with a printed strip monopole, which is simply fed inside the horn with cavity back. The combination effect of two radiators produces multiple resonances frequency and provides wideband 51.65% of 10 dB return loss impedance bandwidth centered at 15.1 GHz. The designed HDRIPHA provides an average gain of 15 dBi with flexibility in the impedance bandwidth, and the far‐field radiation characteristics appear to be satisfied within the operating bandwidth. Both simulation and measurement results for the gain, reflection characteristics, and radiation patterns of the designed HDRIPHA over the operating frequency range of 10–18 GHz are presented. The measured results were compared and have been found to have good agreement as predicted in the simulated results. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:1299–1303, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27586
Mushroom‐shaped dielectric resonator antenna for WiMAX applications
Authors: Kumari Runa , Behera Santanu Kumar
Published: March 2013

A compact mushroom‐shaped dielectric resonator antenna (MSDRA) excited by microstrip line feeding, with partial ground plane has been designed and studied theoretically as well as experimentally. The proposed antenna has been developed for world‐wide interoperability for Microwave Access (WiMAX) applications centered at about 3.5 GHz. The total size of the antenna is 62 mm × 50 mm. The gain for the antenna is found to vary from 3 to 3.6 dBi. Parametric studies are performed to investigate the performance of the antenna. The effects of finite ground plane and radius size of mushroom (half cylindrical)‐shaped dielectric resonator on the antenna performance has been evaluated. The investigations on the S‐parameter, gain, directivity, and radiation characteristics show a fairly good agreement which justifies that the MSDRA can be well suited for Wireless communication systems. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:1360–1365, 2013; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.27590
Wideband high‐gain aperture coupled antenna for ku band phased‐array systems
Authors: Bilgic Mustafa Murat , Yegin Korkut
Published: March 2013

Aperture coupled microstrip antenna is presented for Ku band phased‐array applications. We show that radial open circuit terminated microstrip feed and hourglass aperture shape provide better coupling, high gain, wide bandwidth and small in‐band gain variation. Eight‐element antenna array with fixed beam tilt is formed and measured to validate simulations. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:1291–1295, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27594
Inverted‐F antenna with periodic patterned structures for multiband applications
Authors: Yang Xiaodong , Yang Rui , Xie Yongjun , Lei Zhenya , Bao Di , Rahman A. , Hu Haipeng
Published: March 2013

By introducing periodic patterned structures to planar inverted‐F antenna (PIFA), a novel triple‐band antenna has been achieved and is presented.The transmission line model for periodic patterned ground plane loaded PIFA is extracted. Simulations are confirmed by the experimental results, which ensure that the proposed antenna is well suited for WLAN and WiMAX applications. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:1365–1367, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27597
Broadband monopole antenna with convex conical reflector for 802.11a standard
Authors: Všetula P. , Raida Z.
Published: March 2013

In this article, we present a study dealing with the design, optimization, and manufacturing of different versions of a broadband monopole antenna with a convex conical reflector. These antennas are created by a wire monopole that is placed into the axis of a convex conical reflector. The principle of antennas is based on the transformation of the impedance of a coaxial transmission line to the open space impedance via a circular waveguide. The results of simulations performed in CST Microwave Studio are mutually compared. Then, the simulated versions of broadband monopole antennas were optimized with respect to specified objectives. According the available materials, we built selected versions of the antenna and experimentally verified their properties. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:1243–1247, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27598
Investigation of field and diffusion time dependence of the diffusion‐weighted signal at ultrahigh magnetic fields
Authors: Kunz Nicolas , Sizonenko Stéphane V. , Hüppi Petra S. , Gruetter Rolf , van de Looij Yohan
Published: March 2013

Over the last decade, there has been a significant increase in the number of high‐magnetic‐field MRI magnets. However, the exact effect of a high magnetic field strength (B0) on diffusion‐weighted MR signals is not yet fully understood. The goal of this study was to investigate the influence of different high magnetic field strengths (9.4 T and 14.1 T) and diffusion times (9, 11, 13, 15, 17 and 24 ms) on the diffusion‐weighted signal in rat brain white matter. At a short diffusion time (9 ms), fractional anisotropy values were found to be lower at 14.1 T than at 9.4 T, but this difference disappeared at longer diffusion times. A simple two‐pool model was used to explain these findings. The model describes the white matter as a first hindered compartment (often associated with the extra‐axonal space), characterized by a faster orthogonal diffusion and a lower fractional anisotropy, and a second restricted compartment (often associated with the intra‐axonal space), characterized by a slower orthogonal diffusion (i.e. orthogonal to the axon direction) and a higher fractional anisotropy. ApparentT2relaxation time measurements of the hindered and restricted pools were performed. The shortening of the pseudo‐T2value from the restricted compartment withB0is likely to be more pronounced than the apparentT2changes in the hindered compartment. This study suggests that the observed differences in diffusion tensor imaging parameters between the two magnetic field strengths at short diffusion time may be related to differences in the apparentT2values between the pools. Copyright © 2013 John Wiley & Sons, Ltd.
Disease‐modifying therapy for Alzheimer's disease: Challenges and hopes
Authors: Iwata Atsushi , Iwatsubo Takeshi
Published: March 2013

Despite enormous efforts to develop disease‐modifying drugs for Alzheimer's disease (AD), effective therapies have yet to be found. We have endured failure for a number of reasons, such as low specificity in drug candidates, inaccurate diagnosis and incorrect timing in the intervention. To help overcome these problems, modern research findings have been incorporated into new criteria and guidelines for the clinical diagnosis of AD. In addition, attempts to intervene during the earliest stages of the disease are planned, as this is probably when AD is most receptive to disease‐modifying therapies. We discuss these issues and provide perspective into the future of drug development.
Alterations in adipocytokines and cGMP homeostasis in morbid obesity patients reverse after bariatric surgery
Authors: Felipo Vicente , Urios Amparo , García‐Torres Maria L. , El Mlili Nisrin , del Olmo Juan A. , Civera Miguel , Ortega Joaquin , Ferrandez Antonio , Martínez‐Valls Jose , Cassinello Norberto , Montoliu Carmina
Published: March 2013

Objective:

Obesity‐associated nonalcoholic fatty liver disease (NAFLD), covering from simple steatosis to nonalcoholic steatohepatitis (NASH), is a common cause of chronic liver disease. Aberrant production of adipocytokines seems to play a main role in most obesity‐associated disorders. Changes in adipocytokines in obesity could be mediated by alterations in cyclic GMP (cGMP) homeostasis. The aims of this work were: (1) to study the role of altered cGMP homeostasis in altered adipocytokines in morbid obesity, (2) to assess whether these alterations are different in simple steatosis or NASH, and (3) to assess whether these changes reverse in obese patients after bariatric surgery.

Design and Methods:

In 47 patients with morbid obesity and 45 control subjects, the levels in blood of adipocytokines, cGMP, nitric oxide (NO) metabolites, and atrial natriuretic peptide (ANP) were studied. Whether weight loss after a bariatric surgery reverses the changes in these parameters was evaluated.

Results:

NO metabolites and leptin increase (and adiponectin decreases) similarly in patients with steatosis or NASH, suggesting that these changes are due to morbid obesity and not to liver disease. Inflammation and cGMP homeostasis are affected both by morbid obesity and by liver disease. The increases in interleukin 6 (IL‐6), interleukin 18 (IL‐18), plasma cGMP, ANP, and the decrease in cGMP in lymphocytes are stronger in patients with NASH than with steatosis. All these changes reverse completely after bariatric surgery and weight loss, except IL‐18.

Conclusion:

Altered cGMP homeostasis seems to contribute more than inflammation to changes in leptin and adiponectin in morbid obesity.
How best to use partial meal replacement in managing overweight or obese patients with poorly controlled type 2 diabetes
Authors: Leader Natasha J. , Ryan Lynne , Molyneaux Lynda , Yue Dennis K.
Published: March 2013

Objective:

To compare patient compliance and benefits, over 12 months, of 1 versus 2 partial meal replacement (PMR) for the management of overweight/obese subjects with inadequately controlled type 2 diabetes.

Design and Methods:

Thirty‐six overweight patients with inadequately controlled type 2 diabetes (BMI > 27 kg/m2 and HbA1c > 7.5% [58 mmol/mol]) were randomized to receive 1 or 2 PMR/day, while maintaining usual lifestyle. Subjects were seen monthly and adjustment of medications was made to prevent hypoglycemia. Compliance was assessed by counting unused sachets.

Results:

Patients on 2 PMR/day lost almost 4 kg compared with only 0.5 kg in the 1 PMR/day group. This difference was statistically significant (P < 0.05). Overall PMR was about 30% as effective as in our previous study on total meal replacement. Reductions in weight, waist, and HbA1c were better in the 2 PMR/day group while patient dropout and compliance were not worse over a 12‐month period.

Conclusion:

PMR provides a further management option for overweight/obese individuals with type 2 diabetes. The initial recommendation should be 2 PMR/day.
The inverse relation of HDL anti‐oxidative functionality with serum amyloid a is lost in metabolic syndrome subjects
Authors: Dullaart Robin P. F. , de Boer Jan Freark , Annema Wijtske , Tietge Uwe J.F.
Published: March 2013

Objective:

Anti‐oxidative properties of high density lipoproteins (HDL) are relevant for atheroprotection. HDL carry serum amyloid A (SAA), which may impair HDL functionality. We questioned whether HDL anti‐oxidative capacity is determined by SAA.

Design and Methods:

Relationships of HDL anti‐oxidative capacity (% inhibition of low density lipoprotein oxidation in vitro) with SAA were determined in 54 non‐diabetic subjects without metabolic syndrome (MetS) and 68 subjects with MetS (including 51 subjects with Type 2 diabetes mellitus).

Results:

SAA levels were higher in MetS subjects, coinciding higher high sensitive C‐reactive protein (hs‐CRP) and lower HDL cholesterol and apolipoprotein (apo) A‐I levels (P<0.001 for all). HDL anti‐oxidative capacity was not different between subjects with and without MetS (P=0.76), but the HDL anti‐oxidation index (HDL anti‐oxidative capacity multiplied by individual HDL cholesterol concentrations), as a measure of global anti‐oxidative functionality of HDL, was lower in Mets subjects (P<0.001). HDL anti‐oxidative capacity was correlated inversely with SAA levels in subjects without MetS (r=‐0.286, P=0.036). Notably, this relationship was independent of HDL cholesterol or apoA‐I (P<0.05 for both). In contrast, no relation of HDL anti‐oxidative capacity with SAA was observed in MetS subjects (r=0.032, P=0.80). The relationship of SAA with HDL anti‐oxidative capacity was different in subjects with MetS compared to subjects without MetS (P=0.039 for the interaction between the presence of MetS and SAA on HDL anti‐oxidative capacity) taking age and diabetes status into account.

Conclusion:

Higher SAA levels may impair HDL anti‐oxidative functionality. The relationship of this physiologically relevant HDL functionality measure with circulating SAA levels is apparently disturbed in metabolic syndrome.
Preferring thin people does not imply derogating fat people. A rasch analysis of the implicit weight attitude
Authors: Anselmi Pasquale , Vianello Michelangelo , Robusto Egidio
Published: March 2013

Objective:

The meaning of the implicit weight attitude in individuals of different weight by distinguishing the contribution of positive and negative associations to the overall measure was investigated.

Design and Methods:

The implicit weight attitude was assessed using the Implicit Association Test. A Rasch model was used to identify which stimuli most affected the implicit measure. Explicit attitudes were assessed with a thin‐fat preference scale, and thermometer scales for both thin and fat people. The sample consists of 510 individuals categorized according to their BMI.

Results and Conclusion:

A significant implicit preference for thin relative to fat people was observed in all weight groups. In normal weight and obese individuals, the preference was mostly affected by positive stimuli (more easily associated with thin than with fat people). In underweight individuals, the preference was mostly guided by positive (more easily associated with thin than with fat people) and negative (more easily associated with fat than with thin people) stimuli. In overweight individuals, all stimuli contributed to the preference in a similar way. In all weight groups, the implicit weight attitude correlated with the explicit preference and/or the thin thermometer, whereas it never correlated with the fat thermometer. A pro‐thin bias was observed in normal weight and obese individuals, whereas both a pro‐thin and an anti‐fat bias were observed in underweight individuals. A clear preference for thin people relative to fat people was observed in overweight individuals. Therefore, uncritically interpreting the implicit preference for thin people as a sign of derogating fat people might be misleading.
Circulating levels of persistent organic pollutants in relation to visceral and subcutaneous adipose tissue by abdominal MRI
Authors: Roos Vendela , Rönn Monika , Salihovic Samira , Lind Lars , Bavel Bert van , Kullberg Joel , Johansson Lars , Ahlström Håkan , Lind P. Monica
Published: March 2013

Objective:

We and others have shown relationships between circulating levels of persistent organic pollutants (POPs) and different measures of obesity in both cross‐sectional and prospective studies. Since viscerally located fat seems to be the most harmful type, we investigated whether plasma POP levels were more closely related to visceral adipose tissue (VAT) than to subcutaneous adipose tissue (SAT).

Design and Methods:

Thousand hundred and sixteen subjects aged 70 years were investigated in the Prospective Investigation of the Vasculature in Uppsala Seniors (PIVUS) study; 23 POPs were analyzed using high‐resolution gas chromatography/high‐resolution mass spectrometry. Abdominal magnetic resonance imaging, measuring VAT and SAT, respectively, was performed in a representative subsample of 287 subjects.

Results:

The less chlorinated polychlorinated biphenyl (PCB) congeners (105 and 118), and the pesticides dichlorodiphenyldichloroethylene (DDE), hexachlorobenzene (HCB), and trans‐nonachlordane (TNC) were positively related to both VAT and SAT, whereas the more highly chlorinated PCBs (153, 156, 157, 169, 170, 180, 194, 206, and 209) were inversely related to both VAT and SAT. PCB189 was related to the VAT/SAT ratio in an inverted U‐shaped manner (P = 0.0008).

Conclusions:

In conclusion, the results were in accordance with our previous studies using waist circumference and fat mass as obesity measure. However, the novel finding that PCB189 was related to the VAT/SAT ratio deserves further investigation since exposure to this PCB congener, which has previously been linked to diabetes development, might thereby play a role in the distribution of abdominal adipose tissue.
Weight loss can lead to resolution of gastroesophageal reflux disease symptoms: A prospective intervention trial
Authors: Singh Mandeep , Lee Jaehoon , Gupta Neil , Gaddam Srinivas , Smith Bryan K. , Wani Sachin B. , Sullivan Debra K. , Rastogi Amit , Bansal Ajay , Donnelly Joseph E. , Sharma Prateek
Published: March 2013

Objective:Weight gain is an important risk factor for gastroesophageal reflux disease (GERD); however, whether weight loss can lead to resolution of GERD symptoms is not clear. Our aim was to measure the impact of weight loss on GERD symptoms.

Design and Methods:In a prospective cohort study at a tertiary referral center, overweight/obese subjects (BMI 25‐39.9 kg/m2) were enrolled in a structured weight loss program. Weight loss strategies included dietary modifications, increased physical activity and behavioral changes. At baseline and at 6 months, BMI and waist circumference were measured and all participants completed a validated reflux disease questionnaire.

Results: A total of 332 adult subjects, mean age 46 years and 66% women were prospectively enrolled. At baseline, the mean body weight, BMI, and waist circumference were 101 (±18) kg, 35 (±5) kg/m2 and 103 (±13) cm. At 6 months, majority of the subjects (97%) lost weight (average weight loss: 13 ± 7.7 kg) and as compared with baseline, there was a significant decrease in the overall prevalence of GERD (15 vs. 37%; P < 0.01) and the mean GERD symptom score (1.8 vs. 5.5; P < 0.01). Overall, 81% of the subjects had reduction in GERD symptom scores; 65% had complete resolution and 15% had partial resolution of reflux symptoms. There was a significant correlation between % body weight loss and reduction in GERD symptom scores (r = 0.17, P < 0.05).

Conclusions: In conclusion, the overall prevalence of GERD symptoms is high (37%) in overweight and obese subjects. A structured weight loss program can lead to complete resolution of GERD symptoms in the majority of these subjects.
Effect of oligomeric‐modified montmorillonite on morphology and properties of polycarbonate/montmorillonite nanocomposites
Authors: Huang Xiaoling , Su Haiquan , Wang Xiaoli , Zhang Bingbing , Li Jinmei
Published: March 2013

Low‐molecular‐weight copolymers of styrene and vinylbenzyl ammonium salts (oligomeric surfactant) were used to modify montmorillonite (MMT). The oligomeric‐modified MMT showed good thermal stability, which made it suitable to be used for preparing polycarbonate(PC)/MMT nanocomposites at high temperature. A different series of PC/MMT nanocomposites had been prepared by melt processing using a twin screw extruder. The effect of oligomeric surfactant structure and clay loading on the morphology, mechanical property, thermal stability, and color appearance of the nanocomposites were explored. The results of X‐ray diffraction and transmission electron microscopy analyses indicated that the PC/MMT nanocomposites had partially exfoliated structures. The PC/MMT nanocomposites were found to retain light colored, which was important for optical application. Compared to neat PC, the nanocomposites showed better properties of thermal stability and heat insulation. The mechanical properties of the nanocomposites are significantly enhanced by incorporating clay into the PC matrix. The tensile strength of nanocomposites with 2 wt% clay content was up to 55 MPa, which was much higher than that of the neat PC (37 MPa). The maximum tensile modulus value was 19% higher than that of neat PC. POLYM. COMPOS., 2013. © 2013 Society of Plastics Engineers
Preparation and delayed release of poly(lactide‐ co‐glycolide)/ketoconazole composite fiber mats
Authors: Zhang Y.H. , Zhao D.M. , Sang Z. , Sun L.J. , Wang Q.W.
Published: March 2013

In this study, slow release materials–poly(lactide‐co‐glycolide) (PLGA) ultrafine fiber mats containing different ketoconazole (KCZ) contents were prepared and their release behaviors were investigated in vitro. PLGA/KCZ ultrafine fiber mats were prepared via electrospinning and characterized by means of scanning electron microscope, Fourier transform infrared, X‐ray diffraction (XRD), and thermal gravimetric analysis. The slow release properties of PLGA/KCZ fiber mats in vitro were studied by measuring the concentrations of KCZ dissolved in the phosphate buffered solution (pH = 4.5) at a programmed time. Results indicated that KCZ could be dispersed in PLGA very well in a wide range of KCZ content from 10 to 100% with respect to PLGA. Most KCZ in PLGA fibers were physically dispersed. The thermal decomposition temperature of PLGA was lowered due to the incorporation of KCZ. With increased drug concentration, the release amount would increase in unit time. The two‐stage releases would be sustained to achieve the effective utilization of KCZ. POLYM. COMPOS., 2013. © 2013 Society of Plastics Engineers
>1200 V GaN‐on‐silicon Schottky diode
Authors: Boles T. , Varmazis C. , Carlson D. , Palacios T. , Turner G. W. , Molnar R. J.
Published: March 2013

M/A‐COM Technology Solutions has continuing joint development efforts sponsored by the Department of Energy with MIT main campus and MIT Lincoln Laboratory to develop GaN on silicon two and three terminal high voltage/high current switching devices. The initial developmental goals were for a Schottky diode that has a reverse breakdown blocking voltage of >600 V and is capable of handling 10 A of forward current. A comparison of the M/A‐COM Technology Solutions lateral GaN Schottky diode on‐resistance as a function of reverse breakdown voltage for a number of both lateral and vertical GaN Schottky diode geometries taken from the literature is presented. The substrates employed for all of these data points are either sapphire, SiC, silicon, and even one study which utilized single crystal GaN. Also included in this plot are theoretical limits for the basic materials typically used in GaN Schottky diode construction. It can be seen that the reverse breakdown results of approximately 1500 V for M/A‐COM Technology Solutions lateral anode connected field GaN Schottky diodes on silicon substrates compare extremely favorably with the reported performance of the state‐of‐the‐art devices, regardless of substrate material or design geometry. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Estimation of effective mass and subbands in multi‐quantum wells using polarized light irradiation
Authors: Tanaka K. , Happo N. , Fujiwara M. , Kotera N.
Published: March 2013

Nonparabolic nature of optical interband transitions of multi‐quantum wells structure is important for related device designs. The optical interband transitions of In0.53Ga0.47As/In0.52Al0.48As MQWs including 20‐nm‐wide well clearly appeared on photocurrent spectra with polarized light source. The nonparabolic nature of conduction subbands was decided from experimental interband transitions. The electron effective mass smoothly increased from 0.041 m0 to 0.07 m0 in the conduction quantum well. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
p‐Coumaric Acid Activates the GABA‐A Receptor In Vitro and is Orally Anxiolytic In Vivo
Authors: Scheepens Arjan , Bisson Jean‐Francois , Skinner Margot
Published: March 2013

The increasing prevalence and social burden of subclinical anxiety in the western world represents a significant psychosocial and financial cost. Consumers are favouring a more natural and nonpharmacological approach for alleviating the effects of everyday stress and anxiety. The gamma‐aminobutyric acid (GABA) receptor is the primary mediator of central inhibitory neurotransmission, and GABA‐receptor agonists are well known to convey anxiolytic effects. Using an in vitro screening approach to identify naturally occurring phytochemical GABA agonists, we discovered the plant secondary metabolite p‐coumaric acid to have significant GABAergic activity, an effect that could be blocked by co‐administration of the specific GABA‐receptor antagonist, picrotoxin. Oral administration of p‐coumaric acid to rodents induced a significant anxiolytic effect in vivo as measured using the elevated plus paradigm, in line with the effects of oral diazepam. Given that p‐coumaric acid is reasonably well absorbed following oral consumption in man and is relatively nontoxic, it may be suitable for the formulation of a safe and effective anxiolytic functional food. Copyright © 2013 John Wiley & Sons, Ltd.
A VISUAL FRAMEWORK FOR DISPLAYING, COMMUNICATING AND COORDINATING A RIVER RESTORATION MONITORING PROJECT
Authors: Podolak C. J. P.
Published: March 2013

A visual framework to display complex river restoration monitoring plans is proposed. The framework provides for four dimensions of information—spatial coverage, and the frequency, density and type of measurement to be evaluated—in a concise and transparent fashion. It is not only useful as a display and communication tool but also facilitates identification of overlaps, gaps and inefficiencies. The visual framework is particularly useful for coordinating multiple monitoring efforts and for communicating or negotiating modifications. An example application of the framework is presented using the multi‐year monitoring effort surrounding the removal of the Marmot Dam from the Sandy River, OR. Copyright © 2013 John Wiley & Sons, Ltd.