bluuebunny/crossref_metadata_2025_split huggingface dataset:
Investigation of the power transistor size related to the efficiency of switching‐mode RF CMOS power amplifier
Authors: Hwang Hoyong , Seo Donghwan , Park Jonghoon , Park Changkun 
Published: November 2013

ABSTRACTIn this work, we analyzed the efficiency of a switching‐mode RF CMOS power amplifier with the following design parameters: the on resistance and the parasitic capacitance of the power transistor. The power amplifier is composed of a class‐D type driver stage and a class‐E type power stage. The power consumption of the driver stage, the load impedance of the power stage, and the loss of the output matching networks are considered for a numerical analysis. We investigated the normalized drain efficiency according to the variable supply voltage of the power stage for polar transmitter applications. From the simulated results of the power amplifier, we successfully proved the feasibility of using the numerical analysis. The designed power amplifier is implemented using 0.13 μm RF CMOS process to verify the numerical results by means of an experiment. A distributed active transformer is used for an output matching network. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:110–117, 2014
Pattern and frequency reconfigurable monopole disc antenna using PIN diodes and MEMS switches
Authors: Abou Al‐alaa Mohammed , Elsadek H. A. , Abdallah E. A. , Hashish E. A. 
Published: November 2013

ABSTRACTDual reconfigurable microstrip disc antenna is investigated in this article starting from conventional disc. Modifications are added to produce three reconfigurable shapes. First is pattern reconfigurability by rotating the radiation pattern 60°. Second is frequency reconfigurability. Third shape is dual reconfigurability that merges between frequency and radiation pattern changes. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:187–195, 2014
Frequency‐reconfigurable monopole antenna with wide tuning range for cognitive radio
Authors: Cao Yunfei , Cheung S. W. , Sun X. L. , Yuk T. I. 
Published: November 2013

ABSTRACTThe design of a frequency‐reconfigurable planar monopole antenna with a wide tuning range for cognitive radio is presented. The radiator of the antenna consists of two sections, Section I and Section II, which are connected together using a PIN‐diode. Section I is meandering and responsible for generating a high‐frequency band at about 2.69 GHz. Section II has a U‐shape and, together with Section I, generates a low‐frequency band at about 2.39 GHz. The PIN‐diode is used to select whether only Section I or both Sections I and II together to work as the radiator for the antenna. The radiator has a very compact size of only 11.5 × 8.4 mm2. Continuous tuning for the low‐ and high‐frequency bands is accomplished by placing a varactor on Section I of the radiator. The varactor and the PIN diode are biased using very simple DC circuits. The frequency‐reconfigurable antenna is studied, designed, and optimized using computer simulation. Measurement is used for verification of the simulation results. Results show that the antenna can be tuned from 2.69 to 3.0 GHz using Section I and from 2.39 to 2.62 GHz using both Sections I and II together. Using the PIN‐diode, the antenna can achieve a wide tuning range of 2.39 to 3.0 GHz. The antenna performance in terms of tuning range, radiation pattern, realized peak gain, and efficiency is presented. The feeding cable used in measurement causes substantial discrepancies between the simulated and measured results. A simulation cable model is used to verify such cable effects. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:145–152, 2014
1–6 GHz ultrawideband 4 W single‐ended GaN power amplifier
Authors: Giofre Rocco , Colantonio Paolo , Giannini Franco 
Published: November 2013

ABSTRACTIn this contribution, the design approach and the experimental results of an ultrawideband power amplifier in GaN technology is presented. The amplifier is designed in a single‐ended configuration by using a 0.5 μm GaN HEMT with 1 mm gate periphery. The realized amplifier shows an efficiency higher than 40% with an output power greater than 36 dBm and an associated gain around 10 dB from 1 to 6 GHz. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:215–217, 2014
Prototype phantoms for characterization of ultralow field magnetic resonance imaging
Authors: Boss Michael A. , Mates John A. B. , Busch Sarah E. , SanGiorgio Paul , Russek Stephen E. , Buckenmaier Kai , Irwin Kent D. , Cho Hsiao‐Mei , Hilton Gene C. , Clarke John 
Published: November 2013

PurposePrototype phantoms were designed, constructed, and characterized for the purpose of calibrating ultralow field magnetic resonance imaging (ULF MRI) systems. The phantoms were designed to measure spatial resolution and to quantify sensitivity to systematic variation of proton density and relaxation time, T1.MethodsThe phantoms were characterized first with conventional magnetic resonance scanners at 1.5 and 3 T, and subsequently with a prototype ULF MRI scanner between 107 and 128
.ResultsThe ULF system demonstrated a 2‐mm spatial resolution and, using T1 measurements, distinguished aqueous solutions of MnCl2 differing by 20
[Mn2+].ConclusionThe prototype phantoms proved well‐matched to ULF MRI applications, and allowed direct comparison of the performance of ULF and clinical systems. Magn Reson Med 72:1793–1800, 2014. © 2013 Wiley Periodicals, Inc.
Difluoro‐ and Trifluoromethylation of Electron‐Deficient Alkenes in an Electrochemical Microreactor
Authors: Arai Kenta , Watts Kevin , Wirth Thomas 
Published: November 2013

AbstractElectrochemical microreactors, which have electrodes integrated into the flow path, can afford rapid and efficient electrochemical reactions without redox reagents due to the intrinsic properties of short diffusion distances. Taking advantage of electrochemical microreactors, Kolbe electrolysis of di‐ and trifluoroacetic acid in the presence of various electron‐deficient alkenes was performed under constant current at continuous flow at room temperature. As a result, di‐ and trifluoromethylated compounds were effectively produced in either equal or higher yields than identical reactions under batch conditions previously reported by Uneyamas group. The strategy of using electrochemical microreactor technology is useful for an effective fluoromethylation of alkenes based on Kolbe electrolysis in significantly shortened reaction times.
CLL/SLL diagnosed in an adolescent
Authors: Luskin Marlise , Wertheim Gerald , Morrissette Jennifer , Daber Robert , Biegel Jaclyn , Wilmoth Donna , Kersun Leslie , King Rebecca , Paessler Michele , Simon Cara , Aplenc Richard , Loren Alison 
Published: November 2013

AbstractChronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) is a disease of older adults. Pediatric CLL/SLL is vanishingly rare in the literature. We present a case of CLL/SLL diagnosed in a 17‐year‐old male. The pathologic findings of this case were those of classic CLL/SLL with an ATM deletion, a characteristic genetic abnormality in CLL/SLL. Management guidelines for CLL/SLL are tailored to older adults making determination of the optimal therapy for this patient a unique challenge. Pediatr Blood Cancer 2014;61:1107–1110. © 2013 Wiley Periodicals, Inc.
Characterisation of the Metabolism of Pogostone In Vitro and In Vivo Using Liquid Chromatography with Mass Spectrometry
Authors: Li Yucui , Su Ziren , Lin Shuhai , Li Chuwen , Zhao Ya , Gao Xiang , Lai Yongquan , Wu Xiaoli , Wu Hanzhi , Cai Zongwei , Lai Xiaoping 
Published: November 2013

ABSTRACTIntroductionPogostone possesses potent anti‐bacterial and anti‐fungal activities and has been used for the quality control of essential oil of Pogostemon cablin. Pogostone is easily absorbed after oral administration but its metabolism in mammals remains elusive.ObjectiveTo investigate the metabolic profile of pogostone in vitro and in vivo.MethodsHigh‐performance liquid chromatography coupled with mass spectrometry (LC–MS) techniques were employed. Orbitrap MS and ion trap tandem mass spectrometry (MS/MS) were utilised to analyse the metabolism of pogostone by virtue of the high sensitivity and high selectivity in the measurement. In vitro experiment was carried out using rat liver microsomes while the in vivo study was conducted on rats, which were orally administered with pogostone (80 mg/kg).ResultsIn total, three mono‐hydroxylated, one di‐hydroxylated, one mono‐oxygenated, one di‐oxygenated metabolite, one hydrolysis and one hydroxy conjugated metabolites were found. In addition hydroxylation was demonstrated to be a major metabolic pathway of pogostone.ConclusionLC–MS was demonstrated to be a powerful tool for the metabolite identification of pogostone. The tentative identification of metabolites provides an insight for the metabolic clues of pogostone. Copyright © 2013 John Wiley & Sons, Ltd.
Enhancement of redox stability and electrochromic performance of aromatic polyamides by incorporation of (3,6‐dimethoxycarbazol‐9‐yl)‐triphenylamine units
Authors: Wang Hui‐Min , Hsiao Sheng‐Huei 
Published: November 2013

ABSTRACTNew series aromatic polyamides with (carbazol‐9‐yl)triphenylamine units were synthesized from a newly synthesized diamine monomer, 4,4′‐diamino‐4″‐(3,6‐dimethoxycarbazol‐9‐yl) triphenylamine, and aromatic dicarboxylic acids via the phosphorylation polyamidation technique. These polyamides exhibit good solubility in many organic solvents and can be solution‐cast into flexible and strong films with high thermal stability. They show well‐defined and reversible redox couples during oxidative scanning, with a strong color change from colorless neutral form to yellowish green and blue oxidized forms at applied potentials scanning from 0.0 to 1.3 V. They show enhanced redox‐stability and electrochromic performance as compared to the corresponding analogs without methoxy substituents on the active sites of the carbazole unit. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 272–286
Architecture and function of metallopeptidase catalytic domains
Authors: Cerdà‐Costa Núria , Xavier Gomis‐Rüth Francesc 
Published: November 2013

AbstractThe cleavage of peptide bonds by metallopeptidases (MPs) is essential for life. These ubiquitous enzymes participate in all major physiological processes, and so their deregulation leads to diseases ranging from cancer and metastasis, inflammation, and microbial infection to neurological insults and cardiovascular disorders. MPs cleave their substrates without a covalent intermediate in a single‐step reaction involving a solvent molecule, a general base/acid, and a mono‐ or dinuclear catalytic metal site. Most monometallic MPs comprise a short metal‐binding motif (HEXXH), which includes two metal‐binding histidines and a general base/acid glutamate, and they are grouped into the zincin tribe of MPs. The latter divides mainly into the gluzincin and metzincin clans. Metzincins consist of globular ∼130–270‐residue catalytic domains, which are usually preceded by N‐terminal pro‐segments, typically required for folding and latency maintenance. The catalytic domains are often followed by C‐terminal domains for substrate recognition and other protein–protein interactions, anchoring to membranes, oligomerization, and compartmentalization. Metzincin catalytic domains consist of a structurally conserved N‐terminal subdomain spanning a five‐stranded β‐sheet, a backing helix, and an active‐site helix. The latter contains most of the metal‐binding motif, which is here characteristically extended to HEXXHXXGXX(H,D). Downstream C‐terminal subdomains are generally shorter, differ more among metzincins, and mainly share a conserved loop—the Met‐turn—and a C‐terminal helix. The accumulated structural data from more than 300 deposited structures of the 12 currently characterized metzincin families reviewed here provide detailed knowledge of the molecular features of their catalytic domains, help in our understanding of their working mechanisms, and form the basis for the design of novel drugs.
Plant resistance to aphid feeding: behavioral, physiological, genetic and molecular cues regulate aphid host selection and feeding
Authors: Smith C Michael , Chuang Wen‐Po 
Published: November 2013

AbstractAphids damage major world food and fiber crops through direct feeding and transmission of plant viruses. Fortunately, the development of many aphid‐resistant crop plants has provided both ecological and economic benefits to food production. Plant characters governing aphid host selection often dictate eventual plant resistance or susceptibility to aphid herbivory, and these phenotypic characters have been successfully used to map aphid resistance genes. Aphid resistance is often inherited as a dominant trait, but is also polygenic and inherited as recessive or incompletely dominant traits. Most aphid‐resistant cultivars exhibit constitutively expressed defenses, but some cultivars exhibit dramatic aphid‐induced responses, resulting in the overexpression of large ensembles of putative aphid resistance genes. Two aphid resistance genes have been cloned. Mi‐1.2, an NBS‐LRR gene from wild tomato, confers resistance to potato aphid and three Meloidogyne root‐knot nematode species, and Vat, an NBS‐LRR gene from melon, controls resistance to the cotton/melon aphid and to some viruses. Virulence to aphid resistance genes of plants occurs in 17 aphid species – more than half of all arthropod biotypes demonstrating virulence. The continual appearance of aphid virulence underscores the need to identify new sources of resistance of diverse sequence and function in order to delay or prevent biotype development. © 2013 Society of Chemical Industry
Challenging Beliefs, Practices, and Content: How Museum Educators Change
Authors: ALLEN LAUREN B. , CROWLEY KEVIN J. 
Published: November 2013

ABSTRACTEducators in informal settings can be a key part of the learning experience, yet they are often poorly supported as professionals. This study followed the professional development of museum educators who participated in iterative implementation of a new school trip program focused on climate change. The learner‐centered pedagogy, inquiry format, and controversial content of this program all presented challenges to the educators’ existing models of learning and teaching in the museum. We offer four case studies that explore how part‐time museum docents engaged in reflective practice through iterative implementation and how their approaches to learning and teaching in the museum changed, or failed to change. Findings have implications for addressing the challenge of effective professional development for informal educators, particularly in content areas that may be scientifically challenging or socially controversial.
Background Stress Inventory: Developing a Measure of Understudied Stress
Authors: Terrill Alexandra L. , Gjerde Jill M. , Garofalo John P. 
Published: November 2013

AbstractBackground stress is an understudied source of stress that involves both ambient stress and daily hassles upon which new stressors are superimposed. To date, an accurate measure of the background stress construct has not been available. We developed the Background Stress Inventory, a 25‐item self‐report measure that asks respondents to indicate how distressed they have felt over the past month and the majority of the past year across five domains: financial, occupation, environment, health and social. Seven hundred seventy‐two participants completed the paper‐and‐pencil measure; the sample was randomly split into two separate subsamples for analyses. Exploratory factor analysis suggested five factors corresponding to these domains, and confirmatory factor analysis showed acceptable global fit (X2(255) = 456.47, comparative fit index = 0.94, root mean square error of approximation = 0.045). Cronbach's alpha (0.89) indicated good internal reliability. Construct validity analyses showed significant positive relationships with measures of perceived stressfulness (r = 0.62) and daily hassles (0.41),p's < 0.01. Depressive symptoms (0.62) and basal blood pressure (0.21) were both significantly associated with background stress,p's < 0.01. The importance of the proposed measure is reflected in the limited research base on the impact of background stress. Systematic investigation of this measure will provide insight into this understudied form of chronic stress and its potential influence on both psychological and physical endpoints. Copyright © 2013 John Wiley & Sons, Ltd.
Stat–The First Year
Authors: Fisher Nicholas I 
Published: November 2013

Stat, a new statistical journal designed for rapid communication of interesting and novel research, was launched in August 2012. During its first year of operation, 21 articles were published on a wide variety of topics and with theory inspired by a diverse range of applications. Additionally, an associated blog, StatBlog, was established with its own panel of Associate Editors to enable rapid and timely discussion of published articles.This report and an associated post on StatBlog reflect briefly on the establishment of the journal, and on current and emerging issues relating to publication of statistical research. Copyright © 2013 John Wiley & Sons, Ltd.
Urban rivers: novel ecosystems, new challenges
Authors: Francis Robert A. 
Published: November 2013

Urban rivers can be considered novel or hybrid ecosystems, and as such have experienced substantial biotic and abiotic changes that render them problematic to return to historic system states. Many urban river interventions have limited ecological benefits because such novelty is not considered, and fundamental changes in state are extremely difficult, if not impossible, to reverse while maintaining the societal functions of the system. Consequently, interventions have tended to focus on societal benefits rather than ecological improvements. But perhaps a more appropriate response is to embrace the ecological novelty inherent to urban rivers rather than trying to reverse or remove it, and find ways to enhance ecological function alongside novel conditions and species assemblages. Ecological engineering techniques have only been applied in a limited way to heavily urbanized rivers, but may represent the best options available within these highly compromised systems. The development of such techniques presents several challenges, including understanding and accepting biotic and abiotic novelty, increasing ecological functioning and resilience rather than restoring extirpated species, and rigorously testing interventions to determine efficacy. In part this will require a cultural shift in perception of urban rivers, particularly among managers, engineers and conservationists, to allow novel habitat creation and the establishment of atypical biotic assemblages. Such change sits within a wider ecological agenda to incorporate a greater range of species alongside humans in the urban environment, and improve urban ecosystem services. Urban rivers also present notable scientific opportunities, including more radical experimentation, system cocreation, and comparisons across global urban regions. WIREs Water 2014, 1:19–29. doi: 10.1002/wat2.1007This article is categorized under:

Water and Life > Conservation, Management, and Awareness
Water and Life > Nature of Freshwater Ecosystems
Vertebrate female germline—the acquisition of femaleness
Authors: Tanaka Minoru 
Published: November 2013

The cellular and molecular characteristics of female germ cells have primarily been studied in the mammalian ovary. In most female mammals, all primordial germ cells (PGCs) develop into oocytes early during ovary formation, and germline stem cells are few in number or absent in postnatal ovaries (Lei L, Spradling AC. Female mice lack adult germ‐line stem cells but sustain oogenesis using stable primordial follicles. Proc Natl Acad Sci USA 2013, 110:8585–8590). Research efforts in the field have largely focused on meiosis and follicular development, but a fundamental question regarding establishment of femaleness, which is very important to understand the ‘female’ germline, has not been discussed sufficiently. Recent work has revealed the presence of germline stem cells in the vertebrate ovary, using the teleost fish, medaka (Oryzias latipes) (Nakamura S, Kobayashi K, Nishimura T, Higashijima S, Tanaka, M. Identification of germline stem cells in the ovary of teleost medaka. Science 2010, 328:1561–1563). This discovery allows direct comparison between female and male germline stem cells and raises an interesting and heretofore unaddressed issue regarding femaleness of germline stem cells. In this article, the germ cell behavior in the ovaries of different species is reviewed and compared, the molecular mechanisms underlying the generation of female germ cells are discussed, and the relationship between female germ cells and the surrounding somatic cells is examined.This article is categorized under:

Early Embryonic Development > Gametogenesis
Adult Stem Cells, Tissue Renewal, and Regeneration > Tissue Stem Cells and Niches
Comparative Development and Evolution > Organ System Comparisons Between Species
Is the Gene-Environment Interaction Paradigm Relevant to Genome-Wide Studies? The Case of Education and Body Mass Index
Authors: Boardman Jason D. , Domingue Benjamin W. , Blalock Casey L. , Haberstick Brett C. , Harris Kathleen Mullan , McQueen Matthew B. 
Published: November 2013

AbstractThis study uses data from the Framingham Heart Study to examine the relevance of the gene-environment interaction paradigm for genome-wide association studies (GWAS). We use completed college education as our environmental measure and estimate the interactive effect of genotype and education on body mass index (BMI) using 260,402 single-nucleotide polymorphisms (SNPs). Our results highlight the sensitivity of parameter estimates obtained from GWAS models and the difficulty of framing genome-wide results using the existing gene-environment interaction typology. We argue that SNP-environment interactions across the human genome are not likely to provide consistent evidence regarding genetic influences on health that differ by environment. Nevertheless, genome-wide data contain rich information about individual respondents, and we demonstrate the utility of this type of data. We highlight the fact that GWAS is just one use of genome-wide data, and we encourage demographers to develop methods that incorporate this vast amount of information from respondents into their analyses.
Cumulative Childhood Adversity, Educational Attainment, and Active Life Expectancy Among U.S. Adults
Authors: Montez Jennifer Karas , Hayward Mark D. 
Published: November 2013

AbstractStudies of the early-life origins of adult physical functioning and mortality have found that childhood health and socioeconomic context are important predictors, often irrespective of adult experiences. However, these studies have generally assessed functioning and mortality as distinct processes and used cross-sectional prevalence estimates that neglect the interplay of disability incidence, recovery, and mortality. Here, we examine whether early-life disadvantages both shorten lives and increase the number and fraction of years lived with functional impairment. We also examine the degree to which educational attainment mediates and moderates the health consequences of early-life disadvantages. Using the 1998–2008 Health and Retirement Study, we examine these questions for non-Hispanic whites and blacks aged 50–100 years using multistate life tables. Within levels of educational attainment, adults from disadvantaged childhoods lived fewer total and active years, and spent a greater portion of life impaired compared with adults from advantaged childhoods. Higher levels of education did not ameliorate the health consequences of disadvantaged childhoods. However, because education had a larger impact on health than did childhood socioeconomic context, adults from disadvantaged childhoods who achieved high education levels often had total and active life expectancies that were similar to or better than those of adults from advantaged childhoods who achieved low education levels.