bluuebunny/crossref_metadata_2025 huggingface dataset:
Structural, thermodynamic, and kinetic basis for the activities of some nucleic acid repair enzymes
Authors: Nevinsky Georgy A.
Published: May 2011

X‐ray structural analysis provides no quantitative estimate of the relative contribution of specific and nonspecific or strong and weak interactions to the total affinity of enzymes for nucleic acids. We have shown that the interaction between enzymes and long nucleic acids at the molecular level can be successfully analyzed by the method of stepwise increase in ligand complexity (SILC). In the present review we summarize our studies of human uracil DNA glycosylase and apurinic/apyrimidinic endonuclease, E. coli 8‐oxoguanine DNA glycosylase and RecA protein using the SILC approach. The relative contribution of structural (X‐ray analysis data), thermodynamic, and catalytic factors to the discrimination of specific and nonspecific DNA by these enzymes at the stages of complex formation, the following changes in DNA and enzyme conformations and especially the catalysis of the reactions is discussed. Copyright © 2011 John Wiley & Sons, Ltd.
Identification of the epitope for anti‐cystatin C antibody
Authors: Śladewska Anna , Szymańska Aneta , Kordalska Marlena , Lewandowska Agnieszka , Kołodziejczyk Aleksandra S. , Paraschiv Gabriela , Przybylski Michael , Czaplewska Paulina
Published: May 2011

Human cystatin C (hCC), like many other amyloidogenic proteins, has been shown to form dimers by exchange of subdomains of the monomeric protein. Considering the model of hCC fibrillogenesis by propagated domain swapping, it seems possible that inhibition of this process should also suppress the entire process of dimerization and fibrillogenesis which leads to specific amyloidosis (hereditary cystatin C amyloid angiopathy (HCCAA)). It was reported that exogenous agents like monoclonal antibody against cystatin C are able to suppress formation of cystatin C dimers. In the effort to find a way of controlling the cystatin fibrillization process, the interactions between monoclonal antibody Cyst‐13 and cystatin C were studied in detail. The present work describes the determination of the epitope of hCC to a monoclonal antibody raised against cystatin C, Cyst‐13, by MALDI mass spectrometry, using proteolytic excision of the immune complex. The shortest epitope sequence was determined as hCC(107‐114). Affinity studies of synthetic peptides revealed that the octapeptide with epitope sequence does not have binding ability to Cyst‐13, whereas its longer counterpart, hCC(105–114), binds the studied antibody. The secondary structure of the peptides with epitope sequence was studied using circular dichroism and NMR spectroscopy. Copyright © 2011 John Wiley & Sons, Ltd.
Molecularly imprinted polyaniline film for ascorbic acid detection
Authors: Roy Abani Kumar , S Nisha V. , Dhand Chetna , Malhotra Bansi D.
Published: May 2011

Molecularly imprinted polyaniline (PANI) film (∼100 nm thick) has been electrochemically fabricated onto indium–tin–oxide (ITO) coated glass plate using ascorbic acid (AA) as template molecule. Fourier transform infra‐red spectroscopy, scanning electron microscopy, cyclic voltammetry and differential pulse voltammetry (DPV) studies indicate the presence of AA in PANI matrix, which also acts as a dopant for PANI. Further, the AA selective molecularly imprinted PANI electrode (AA‐MI‐PANI/ITO) has been developed via over‐oxidation of AA doped PANI electrode which leads to the removal of AA moieties from PANI film. The response studies using DPV technique have revealed that this molecularly imprinted AA‐MI‐PANI/ITO electrode can detect AA in the range of 0.05–0.4 mM with detection limit of 0.018 mM and sensitivity of 1.2 × 10−5 AmM−1. Interestingly, this AA‐MI‐PANI/ITO electrode shows excellent reusability, selectivity and stability. Copyright © 2011 John Wiley & Sons, Ltd.
Azurin modulates the association of Mdm2 with p53: SPR evidence from interaction of the full‐length proteins
Authors: Domenici Fabio , Frasconi Marco , Mazzei Franco , D'Orazi Gabriella , Bizzarri Anna Rita , Cannistraro Salvatore
Published: May 2011

The tumour suppressor p53 plays a crucial role in cell stress response and its anticancer activity is mainly down‐regulated by the oncoprotein Mdm2 that, upon binding to p53, blocks its transcriptional activity and promotes its ubiquitin‐dependent degradation. Targeting Mdm2–p53 interaction is believed to be the most direct of all p53‐activating strategies to treat tumours in which p53 has retained its wild‐type function. The bacterial protein Azurin has been shown to bind p53, inhibiting cancer cell proliferation likely through a post‐translational increasing of the p53 level. This apparent antagonist action with respect to the Mdm2–p53 functional interaction suggests that binding of Azurin to p53 might interfere with the Mdm2–p53 association and, thus, preventing p53 from degradation. Toward this end, a detailed kinetic characterization of the binding interaction of these three proteins has been performed by surface plasmon resonance. The occurrence of specific binary interactions of both Azurin and Mdm2 with p53, as investigated more appropriately in their full‐length conformation, is ascertained and the corresponding association and dissociation rate constants are measured. Interestingly enough, the three proteins are likely engaged in a ternary interaction, whose kinetics points out that binding of Azurin to p53 causes a significant decrease of the Mdm2–p53 association rate constant and binding affinity, without hindering the accessibility of Mdm2 to the binding pocket of p53. The Azurin‐induced p53 conformational change, as demonstrated by circular dichroism, suggests that the protein may affect Mdm2–p53 association through an allosteric mechanism, which could give an useful insight into designing new anticancer drugs. Copyright © 2011 John Wiley & Sons, Ltd.
Segmentation of the quadratus lumborum muscle using statistical shape modeling
Authors: Engstrom Craig M. , Fripp Jurgen , Jurcak Valer , Walker Duncan G. , Salvado Olivier , Crozier Stuart
Published: May 2011

Purpose:

To compare automated segmentation of the quadratus lumborum (QL) based on statistical shape modeling (SSM) with conventional manual processing of magnetic resonance (MR) images for segmentation of this paraspinal muscle.

Materials and Methods:

The automated SSM scheme for QL segmentation was developed using an MR database of 7 mm axial images of the lumbar region from 20 subjects (cricket fast bowlers and athletic controls). Specifically, a hierarchical 3D‐SSM scheme for segmentation of the QL, and surrounding psoas major (PS) and erector spinae+multifidus (ES+MT) musculature, was implemented after image preprocessing (bias field correction, partial volume interpolation) followed by image registration procedures to develop average and probabilistic MR atlases for initializing and constraining the SSM segmentation of the QL. The automated and manual QL segmentations were compared using spatial overlap and average surface distance metrics.

Results:

The spatial overlap between the automated SSM and manual segmentations had a median Dice similarity metric of 0.87 (mean = 0.86, SD = 0.08) and mean average surface distance of 1.26 mm (SD = 0.61) and 1.32 mm (SD = 0.60) for the right and left QL muscles, respectively.

Conclusion:

The current SSM scheme represents a promising approach for future automated morphometric analyses of the QL and other paraspinal muscles from MR images. J. Magn. Reson. Imaging 2011;33:1422–1429. © 2011 Wiley‐Liss, Inc.
Reproducibility of renal perfusion MR imaging in native and transplanted kidneys using non‐contrast arterial spin labeling
Authors: Artz Nathan S. , Sadowski Elizabeth A. , Wentland Andrew L. , Djamali Arjang , Grist Thomas M. , Seo Songwon , Fain Sean B.
Published: May 2011

Purpose:

To examine both inter‐visit and intra‐visit reproducibility of a MR arterial spin labeling (ASL) perfusion technique in native and transplanted kidneys over a broad range of renal function.

Materials and Methods:

Renal perfusion exams were performed at 1.5 T in a total of 24 subjects: 10 with native and 14 with transplanted kidneys. Using a flow‐sensitive alternating inversion recovery (FAIR) ASL scheme, 32 control/tag pairs were acquired and processed using a single‐compartment model. Two FAIR‐ASL MR exams were performed at least 24 h apart on all the subjects to assess inter‐visit reproducibility. ASL perfusion measurements were also repeated back‐to‐back within one scanning session in 8 native subjects and in 12 transplant subjects to assess intra‐visit reproducibility. Intra‐class correlations (ICCs) and coefficients of variation (CVs) were calculated as metrics of reproducibility.

Results:

Intra‐visit ICCs ranged from 0.96 to 0.98 while CVs ranged from 4.8 to 6.0%. Inter‐visit measurements demonstrated slightly more variation with ICCs from 0.89 to 0.94 and CVs from 7.6 to 13.1%. Medullary perfusion demonstrated greater variability compared with cortical blood flow: intra‐visit ICCs from 0.72 to 0.78 and CVs from 16.7 to 26.7%, inter‐visit ICCs from 0.13 to 0.63 and CVs from 19.8 to 37%.

Conclusion:

This study indicates that a FAIR‐ASL perfusion technique is reproducible in the cortex of native and transplanted kidneys over a broad range in renal function. In contrast, perfusion measurements in the medulla demonstrated moderate to poor reproducibility for intra‐visit and inter‐visit measures respectively. J. Magn. Reson. Imaging 2011;33:1414–1421. © 2011 Wiley‐Liss, Inc.
Reduced transverse relaxation rate (RR2) for improved sensitivity in monitoring myocardial iron in thalassemia
Authors: Cheung Jerry S. , Au Wing‐Yan , Ha Shau‐Yin , Kim Daniel , Jensen Jens H. , Zhou Iris Y. , Cheung Matthew M. , Wu Yin , Guo Hua , Khong Pek‐Lan , Brown Truman R. , Brittenham Gary M. , Wu Ed X.
Published: May 2011

Purpose:

To evaluate the reduced transverse relaxation rate (RR2), a new relaxation index which has been shown recently to be primarily sensitive to intracellular ferritin iron, as a means of detecting short‐term changes in myocardial storage iron produced by iron‐chelating therapy in transfusion‐dependent thalassemia patients.

Materials and Methods:

A single‐breathhold multi‐echo fast spin‐echo sequence was implemented at 3 Tesla (T) to estimate RR2 by acquiring signal decays with interecho times of 5, 9 and 13 ms. Transfusion‐dependent thalassemia patients (N = 8) were examined immediately before suspending iron‐chelating therapy for 1 week (Day 0), after a 1‐week suspension of chelation (Day 7), and after a 1‐week resumption of chelation (Day 14).

Results:

The mean percent changes in RR2, R2, and R2* off chelation (between Day 0 and 7) were 11.9 ± 8.9%, 5.4 ± 7.7% and −4.4 ± 25.0%; and, after resuming chelation (between Day 7 and 14), −10.6 ± 13.9%, −8.9 ± 8.0% and −8.5 ± 24.3%, respectively. Significant differences in R2 and RR2 were observed between Day 0 and 7, and between Day 7 and 14, with the greatest proportional changes in RR2. No significant differences in R2* were found.

Conclusion:

These initial results demonstrate that significant differences in RR2 are detectable after a single week of changes in iron‐chelating therapy, likely as a result of superior sensitivity to soluble ferritin iron, which is in close equilibrium with the chelatable cytosolic iron pool. RR2 measurement may provide a new means of monitoring the short‐term effectiveness of iron‐chelating agents in patients with myocardial iron overload. J. Magn. Reson. Imaging 2011;33:1510–1516. © 2011 Wiley‐Liss, Inc.
Signal to noise ratio and uncertainty in diffusion tensor imaging at 1.5, 3.0, and 7.0 Tesla
Authors: Polders Daniel L. , Leemans Alexander , Hendrikse Jeroen , Donahue Manus J. , Luijten Peter R. , Hoogduin Johannes M.
Published: May 2011

Purpose:

To compare diffusion tensor imaging (DTI) measurements at ultra high field strength (7 Tesla [T]) in human volunteers with DTI measurements performed at 1.5 and 3 Tesla.

Materials and Methods:

The signal to noise ratio (SNR) and the uncertainty in fitted DTI parameters fractional anisotropy and primary eigenvector are assessed with tractography based regions of interest, measured in nine volunteers at 1.5T, 3T, and 7T with clinically available hardware configurations.

Results:

An increase in SNR is observed on the 7T system compared with the 1.5 or 3T system. The measured increase in SNR at 7T is larger than expected from field strength alone, indicating the large influence of improved receive coil hardware. Additionally, while the average fractional anisotropy remains relatively constant across field strengths, a decrease in uncertainty in the fitted values for fractional anisotropy and the principal eigenvector of the DTI tensor was found. Increased spatial heterogeneity of signal intensities is observed at 7T.

Conclusion:

Given the current hardware constraints, DTI at ultra‐high field strengths is possible with improved performance in selected regions of interest. J. Magn. Reson. Imaging 2011;33:1456–1463. © 2011 Wiley‐Liss, Inc.
Adiabatic localized correlation spectroscopy (AL‐COSY): Application in muscle and brain
Authors: Ramadan Saadallah , Mountford Carolyn E.
Published: May 2011

Purpose:

To describe an enhanced version of a localized correlation spectroscopy (L‐COSY) by introducing adiabatic radiofrequency (RF) pulses for localization in two dimensions. Adiabatic pulses will improve slice selection profile and reduce chemical shift artifacts. Optimized Mao and adiabatic hyperbolic secant pulses are tested in vivo.

Materials and Methods:

Region of interest is localized by a 90° nonselective adiabatic RF pulse followed by two pairs of adiabatic RF pulses and a terminal 90° RF sinc pulse. Slice profiles for both refocusing pulses and chemical shift artifacts are measured in a water–oil phantom for L‐COSY and AL‐COSY. In vivo results of both COSY sequences are shown from muscle and brain on a 3 Tesla (T) scanner.

Results:

Chemical shift artifacts were reduced with AL‐COSY compared with L‐COSY. Slice profiles of adiabatic pulses were found to be sharper and more symmetrical than those of traditional Mao pulses. One‐dimensional (1D) phantom studies showed longer T2 values using AL‐COSY sequence. Comparison of 2D spectra obtained revealed spectroscopic peak volume improvements in AL‐COSY and less residual water. In vivo 1D comparison showed more inphase and sharper peaks in AL‐COSY spectrum.

Conclusion:

The AL‐COSY sequence is an improved sequence due to sharper slice selection profiles, reduction of chemical shift artifacts, peak volume improvements in 2D techniques, and less J‐modulation. J. Magn. Reson. Imaging 2011;33:1447–1455. © 2011 Wiley‐Liss, Inc.
Diagnostic value of the flow profile in the distal descending aorta by phase‐contrast magnetic resonance for predicting severe coarctation of the aorta
Authors: Muzzarelli Stefano , Ordovas Karen Gomes , Hope Michael D. , Meadows Jeffery J. , Higgins Charles B. , Meadows Alison Knauth
Published: May 2011

Purpose:

To compare aortic flow profiles at the level of the proximal descending (PDAo) and distal descending aorta (DDAo) in patients investigated for coarctation of the aorta (CoA), and compare their respective diagnostic value for predicting severe CoA. Diastolic flow decay in the PDAo predicts severe CoA, but flow measurements at this level are limited by flow turbulence, aliasing, and stent‐related artifacts.

Materials and Methods:

We studied 49 patients evaluated for CoA with phase contrast magnetic resonance imaging (PC‐MRI). Parameters of diastolic flow decay in the PDAo and DDAo were compared. Their respective diagnostic value was compared with the standard reference of transcatheter peak gradient ≥20 mmHg.

Results:

Flow measurement in the PDAo required repeated acquisition with adjustment of encoding velocity or location of the imaging plane in 69% of patients; measurement in the DDAo was achieved in single acquisition in all cases. Parameters of diastolic flow decay in the PDAo and DDAo, including rate‐corrected (RC) deceleration time and RC flow deceleration yielded a good correlation (r = 0.78; P < 0.01, and r = 0.92; P < 0.01), and a similar diagnostic value for predicting severe CoA. The highest diagnostic accuracy was achieved by RC deceleration time at DDAo (sensitivity 85%, specificity 85%).

Conclusion:

Characterization of aortic flow profiles at the DDAo offers a quick and reliable noninvasive means of assessing hemodynamically significant CoA. J. Magn. Reson. Imaging 2011;33:1440–1446. © 2011 Wiley‐Liss, Inc.
The diverse pathology and kinetics of mass, nonmass, and focus enhancement on MR imaging of the breast
Authors: Jansen Sanaz A. , Shimauchi Akiko , Zak Lindsay , Fan Xiaobing , Karczmar Gregory S. , Newstead Gillian M.
Published: May 2011

Purpose:

To compare the pathology and kinetic characteristics of breast lesions with focus‐, mass‐, and nonmass‐like enhancement.

Materials and Methods:

A total of 852 MRI detected breast lesions in 697 patients were selected for an IRB approved review. Patients underwent dynamic contrast enhanced MRI using one pre‐ and three to six postcontrast T1‐weighted images. The “type” of enhancement was classified as mass, nonmass, or focus, and kinetic curves quantified by the initial enhancement percentage (E1), time to peak enhancement (Tpeak), and signal enhancement ratio (SER). These kinetic parameters were compared between malignant and benign lesions within each morphologic type.

Results:

A total of 552 lesions were classified as mass (396 malignant, 156 benign), 261 as nonmass (212 malignant, 49 benign), and 39 as focus (9 malignant, 30 benign). The most common pathology of malignant/benign lesions by morphology: for mass, invasive ductal carcinoma/fibroadenoma; for nonmass, ductal carcinoma in situ (DCIS)/fibrocystic change(FCC); for focus, DCIS/FCC. Benign mass lesions exhibited significantly lower E1, longer Tpeak, and lower SER compared with malignant mass lesions (P < 0.0001). Benign nonmass lesions exhibited only a lower SER compared with malignant nonmass lesions (P < 0.01).

Conclusion:

By considering the diverse pathology and kinetic characteristics of different lesion morphologies, diagnostic accuracy may be improved. J. Magn. Reson. Imaging 2011;33:1382–1389. © 2011 Wiley‐Liss, Inc.
Comparison of a single shot T1‐weighted in‐ and out‐of‐phase magnetization prepared gradient recalled echo with a standard two‐dimensional gradient recalled echo: Preliminary findings
Authors: Herédia Vasco , Ramalho Miguel , de Campos Rafael O.P. , Lee Chang‐Hee , Dale Brian , Vaidean Georgeta D. , Semelka Richard C.
Published: May 2011

Purpose:

To compare in‐phase (IP) /out‐of‐phase (OP) single shot magnetization‐prepared gradient‐recalled‐echo (MP‐GRE) with a standard two‐dimensional gradient‐recalled‐echo (2D‐GRE), and to compare image quality of MP‐GRE in cooperative and noncooperative subjects.

Materials and Methods:

Ninety‐six consecutive subjects (52 males, 44 females; mean age, 53.2 ± 16.7 years), both cooperative (n = 73) and noncooperative (n = 23) subjects who had MRI examinations including precontrast T1‐weighted IP/OP MP‐GRE with or without IP/OP 2D‐GRE were included in the study. The sequences were independently qualitatively evaluated by two radiologists. Quantitative analysis of liver fat index, signal‐to‐noise ratio (SNR) and liver‐lesion contrast‐to‐noise ratio (CNR) was also performed. Data were subjected to statistical analysis.

Results:

The visual detection of the presence or absence of liver steatosis showed no differences between 2D‐GRE and MP‐GRE imaging (k = 1). Minor differences were observed on image quality between MP‐GRE and 2D‐GRE in cooperative subjects, and between MP‐GRE sequences performed in cooperative and noncooperative subjects. Liver fat index results were strongly positively correlated (r = .98; 95% confidence interval [CI] 0.97 to 0.98; P < .0001). Intercept (.14; 95% CI .13 to .15; P < .0001) and slope (.83; 95% CI .79 to .86; P < .0001) were statistically significant.

Conclusion:

IP/OP MP‐GRE and 2D‐GRE comparably demonstrate the presence or absence of hepatic steatosis. Image quality of MP‐GRE was also comparable to 2D‐GRE, and was not substantially adversely affected if subjects were unable to cooperate with breathholding instructions. J. Magn. Reson. Imaging 2011;33:1482–1490. © 2011 Wiley‐Liss, Inc.
Proton resonance frequency shift‐weighted imaging for monitoring MR‐guided high‐intensity focused ultrasound transmissions
Authors: Chen Jyun‐Wen , Huang Teng‐Yi , Peng Hsu‐Hsia , Chen Wen‐Shiang , Tseng Wen‐Yih Isaac
Published: May 2011

Purpose:

To combine temperature‐related information of phase images and magnitude images acquired from an MR spoiled gradient echo sequence using a postprocessing method referred to as PRF‐shift‐weighted imaging (PRFSWI).

Materials and Methods:

Phase images are capable of detecting shifts in proton resonance frequency (PRF) caused by local changes in temperature. Magnitude images provide anatomical information for treatment planning and positioning as well as temperature‐related contrast. We used PRFSWI to produce a phase‐mask and performed multiplication on the magnitude image to increase temperature‐related contrast.

Results:

Through MRI‐guided focused ultrasound (MRIgFUS) experiments (both ex vivo and in vivo), we determined that PRFSWI is capable of enhancing the contrast of a heated area even in the initial stages of transmitting high‐intensity focused ultrasound energy.

Conclusion:

The PRFSWI images are sensitive to changes in temperature and display the heated spot directly in the magnitude images. Although the images do not provide quantitative data related to temperature, this method could be used as a complement to the phase temperature mapping method in the real‐time monitoring of MRIgFUS experiments. J. Magn. Reson. Imaging 2011;33:1474–1481. © 2011 Wiley‐Liss, Inc.
Regions of autumn Eurasian snow cover and associations with North American winter temperatures
Authors: Mote Thomas L. , Kutney Emily R.
Published: May 2011

The extent of snow cover over Eurasia during autumn has been shown to be influential in shaping atmospheric circulation over the Northern Hemisphere the following winter via the Arctic Oscillation (AO), North Atlantic Oscillation (NAO), and the Pacific/North American (PNA) teleconnections. Regions of Eurasian snow cover were derived from Principal Component Analysis and compared to winter temperatures across North America for 1967/1968–2007/2008, excluding 1969/1970 and 1971/1972. The score time series of each principal component was then compared to winter averages of the AO, NAO, and PNA indices in order to identify possible links in the snow‐temperature relationship. Results showed that autumn snow cover from northern Scandinavia to the West Siberian Plain is most significantly associated with winter temperatures over the interior of North America. More (less) frequent snow cover over this region is related to lower (higher) winter temperatures over the interior of North America in January, extending to the eastern and southern United States in February. The greatest temperature response to anomalous snow cover occurred near the geographic centre of North America where winter temperature differences exceeded 5 °C. More (less) frequent autumn snow cover across the eastern Tibetan Plateau was associated with higher (lower) temperatures in the Great Basin and eastern Canada. Copyright © 2011 Royal Meteorological Society
Modelling the effects of land‐use/land‐cover changes on the near‐surface atmosphere in southern South America
Authors: Beltrán‐Przekurat Adriana , Pielke Sr Roger A. , Eastman Joseph L. , Coughenour Michael B.
Published: May 2011

A fully coupled atmospheric‐biospheric regional climate model, GEMRAMS, was used to evaluate potential effects of land‐use/land‐cover changes (LULCC) on near‐surface atmosphere over a southern South American domain at seasonal time scales. In GEMRAMS, leaf area index and canopy conductance are computed based on modelled temperature, solar radiation, and the water status of the soil and air, allowing a two‐way interaction between canopy and atmosphere. Several austral spring‐early summer simulations were conducted using land cover representing current (i.e. agricultural landscape), natural (i.e. before European settlement), and afforestation scenarios for three periods associated with El Niño‐Southern Oscillation (ENSO) conditions. The shift to agriculture resulted in a generalized increase in albedo, reducing the available energy at the near‐surface. (Correction added on 21 September 2011 after original online publication: in the preceding sentence the word ‘decrease’ was corrected to ‘increase’.) The energy partitioning between latent and sensible heat fluxes changed, leading to distinct temperature responses. A shift from grass to agriculture led to cooler and wetter near‐surface atmospheric conditions. Warmer temperatures resulted from the conversion of wooded grasslands or forest to agriculture. The LULCC‐induced signal was spatially heterogeneous and with a seasonal component associated with vegetation phenology. A significant decrease in maximum temperatures in the southern and central Pampas led to a decrease in the diurnal temperature range. Basing on some observational studies in this region our results suggest a potential strong influence of LULCC on the maximum temperatures in central Argentina in summer. Afforestation resulted overall in cooler temperatures. For both LULCC scenarios the direction of the energy fluxes and temperature changes remained in general the same in two extreme ENSO years, although for some vegetation conversions the signal reversed direction. Overall, the impacts were enhanced during a dry year, but the response also depended on the vegetation types involved in the conversion. The effects on precipitation were insignificant in the agriculture‐conversion scenario and a general increase was found in the afforested scenario. Copyright © 2011 Royal Meteorological Society
Innovations: principles and strategies
Authors: Ramadani Veland , Gerguri Shqipe
Published: May 2011

In order for companies to innovate as much as possible it is necessary for them to be familiar with the process of innovation and the principles on which innovation is founded.
Toward a strategic role for employees in corporate governance
Authors: Muthusamy Senthil , Bobinski Pawel A. , Jawahar David
Published: May 2011

In this paper we argue how employee participation in corporate decision‐making augments organizational performance and limits corporate excesses, and we further highlight the significance of codetermination in the context of knowledge work and economy.
Highly Enhanced Nucleating Effect of Melt‐Recrystallized Stereocomplex Crystallites on Poly(L‐lactic acid) Crystallization
Authors: Narita Junichi , Katagiri Mikio , Tsuji Hideto
Published: May 2011

In the general processing temperature range of poly(L‐lactic acid) (PLLA) articles (210–240 °C), PLLA/poly(D‐lactic acid) (PDLA) stereocomplex (SC) crystallites melted just above the endset temperature of SC melting (228–238 °C) and recrystallized during cooling were found to act as the most effective nucleating agents for enhancing the crystallization of PLLA compared to partially melted SC crystallites (211–227 °C) or those melted far above the endset temperature of SC melting (240 and 250 °C) and recrystallized during cooling. The high nucleating effect of the SC crystallites melted in the temperature range of 228–238 °C was found to be caused by their smaller sizes or the larger number of SC crystallites per unit mass. The incorporation of such SC crystallites facilitates the processing of PLLA articles having high crystallinity and, therefore, high heat‐resistance in a shorter period to reduce the production cost.

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Scanning Force Microscopy as Applied to Conformational Studies in Macromolecular Research
Authors: Gallyamov Marat O.
Published: May 2011

The modern state of SFM research on polymer nano‐objects including single chains is discussed in comparison with other similar high‐resolution microscopy techniques. The range of problems to be solved preferentially by SFM is highlighted. Promising methodology to describe quantitatively the morphology of macromolecular objects is proposed. The main benefits of this algorithm seem to be the apparent mathematical correctness as well as the possibility to estimate errors and the confidence of the numbers obtained. Special attention is paid to the dynamic observations of conformational transitions on a substrate in real time regime. This approach allows one to realise direct control of the adsorbed macromolecules by means of exposure to different vapours. Driving forces of the vapour‐induced reorganisation are discussed.

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Noncontact heart rate monitoring using Doppler radar and continuous wavelet transform
Authors: Tariq A. , Ghafouri‐Shiraz H.
Published: May 2011

An algorithm based on wavelet transform is utilized in detecting and examining the heartbeat signal obtained from a Doppler radar.Time–frequency localization properties of wavelet transform were used to examine the signal and provided detail of swift and slow changes in heart rate over very small periods resulting in better determination of the accuracy of the Doppler radar. Till 1 m, a very accurate and robust performance was observed for the Doppler radar. Even at 2‐m heart rate was detectable but not with reasonable accuracy. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26092
Design of broadband dipole for TRI‐band TD‐SCDMA operation
Authors: Wang Y. , Sun B.‐H. , Huang J.‐X. , Wen L.‐H. , Xi D.
Published: May 2011

A printed dipole with rotated tapered arms is of considerable interest as a broadband antenna element, and has good potential for use in low cost wireless base station (tri‐band TD‐SCDMA) antenna applications. The antenna which employs a planar reflector is composed of two tapered arms fed by an integrated balun and loaded with a lumped element (a 0.6 pF capacitor), leading to a broad impedance bandwidth and stable gains. The capacitor and the balun comprise the adjustable matching network. Measured result shows that the antenna provides an impedance bandwidth of 40% for voltage standing wave ratio (VSWR) less than 2. Good radiation performances and gains over the operating band are observed. Parametric study of its performance is also performed to provide more information for the antenna design. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26099
DSC‐SIP method for two‐dimensional scattering problem
Authors: Li Hai , Shao Zhenhai , Yeo Sweeping , Leong Yewkong , Lim Menghiot
Published: May 2011

A generalized high‐order finite‐difference method [discrete singular convolution‐symplectic integrator propagator (DSC‐SIP)] is proposed to analyze the electromagnetic scattering problem in which the time difference is discretized by the SIP and the spatial difference by the DSC.When compared with the standard finite‐difference time‐domain (FDTD) method, the DSC‐SIP method not only has higher stability and accuracy but also can save the computing memory space and CPU time with suitable meshes. Numerical examples are provided to show the high stability and effectiveness of the proposed method. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26104
A quadrature CMOS clapp voltage‐controlled oscillator
Authors: Jang Sheng‐Lyang , Yeh Hsiu‐An , Chang Chia‐Wei , Juang Miin‐Horng , Chen Han‐Sheng
Published: May 2011

A new fully integrated, CMOS Clapp quadrature voltage‐controlled oscillator (QVCO) is presented.The QVCO is composed of two differential n‐core Clapp VCOs coupled by four pMOSFETs and was implemented in the 0.18‐μm CMOS technology with 0.9‐V supply voltage. The die area is 0.574 × 0.866 mm2. At the supply voltage of 0.9 V, the total power consumption is 12.2 mW. The free‐running frequency of the QVCO is tunable from 7.89 to 9.3 GHz as the tuning voltage is varied from 0 to 2 V. The measured phase noise at 1‐MHz frequency offset is −118.65 dBc/Hz at the oscillation frequency of 7.89 GHz, and the figure of merit of the proposed QVCO is about −185.71 dBc/Hz. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26109
Broadband, high gain slot loaded square microstrip array antenna
Authors: Mulgi S. N. , Singh Kishan
Published: May 2011

A novel two‐element right angle slot loaded square microstrip array antenna (TESMAA) is presented for 52.18% of bandwidth and 11.22 dB of gain. The effect of different slots placed in the ground plane is studied for enhancing the bandwidth and gain. It is found that when bow‐tie slot is placed in the ground plane of TESMAA the antenna gives maximum 95.54% of bandwidth and 15.92 dB of gain without affecting the nature of broad side radiation characteristics. The design concepts of antennas are described and experimental results are discussed. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26110
Dual‐band power divider using stepped‐impedance resonators structure
Authors: Zhao Shiwei , Tang Zongxi , Guo Fanyu
Published: May 2011

A novel dual‐band power divider based on a stepped‐impedance resonators structure for good rejection levels in the extended stopband is presented.The stopband is then extended, and the rejection levels are enhanced by collocating transmission zeros with the unwanted peaks. The simulated and measured results of power divider at 2.3 GHz and 4.7 GHz are given. This kind of power divider has the advantage of better rejection levels in the stopband and return loss compared with traditional dual‐band power divider. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26115
Tri‐band, stand‐alone, PIFA with parasitic, inverted‐L plate and vertical ground wall for WLAN applications
Authors: Lee Cheng‐Tse , Su Saou‐Wen
Published: May 2011

A novel, stand‐alone, metal‐plate tri‐band antenna capable of operating in the 2.4, 5.2, and 5.8 GHz WLAN bands is proposed. The antenna occupies the compact size of 5 × 12 × 35 mm3 and mainly comprises a direct‐fed PIFA, a parasitic, inverted‐L (IL) plate, and an antenna ground plane having a vertical ground wall, all constructed from a single metal plate. The parasitic plate is short‐circuited to the ground and provides a space for the signal grounding of the PIFA. The first and the second resonant modes of the PIFA contribute to the 2.4 and 5.8 GHz operation. The frequency ratio can easily be controlled by the meander‐line portion inserted in the PIFA. The additional 5.2‐GHz resonance is generated by the parasitic IL plate. That is, a tri‐WLAN‐band operation can be obtained. Moreover, the antenna is fed by using a mini‐coaxial cable, allowing it to be flexibly deployed inside various wireless devices. The results showed that the antenna operating bands in free space and in a laptop were about the same. The antenna can be used as a quasi‐standard antenna component. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26116
Transition of 94‐GHZ coplanar waveguide to rectangular waveguide on flip‐chip bonding compatible substrate
Authors: Moon Sung‐Woon , Lee Sang‐Jin , Han Min , Rhee Jin‐Koo , Kim Sam‐Dong
Published: May 2011

We demonstrate a 94‐GHz coplanar waveguide (CPW) to rectangular waveguide transition on high permittivity sapphire substrate. Monolithically fabricated uniplanar transition is composed of the fin‐line taper and the open‐type CPW to slotline transition that can be fully integrated with the flip‐chip bonded monolithic microwave integrated circuits (MMICs) on single rigid sapphire substrate. From an optimized design of a low‐loss single‐section transition, we fabricate the back‐to‐back transition for the characterization. The measurements show an insertion loss of ∼1.7 dB at 94 GHz from a single‐section transition, and the performance is successfully verified from a 94‐GHz mixer module assembled with a flip‐chip bonded MMIC mixer. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26121
Fiber optic chemical sensor using fiber coupler probe based on intensity modulation for alcohol detection
Authors: Yasin M. , Harun S. W. , Tan C.F. , Phang S. W. , Ahmad H.
Published: May 2011

A simple intensity modulation based displacement sensor using fiber optic coupler probe is proposed and demonstrated for sensing the concentration of alcohol solution. The intensity of light reduces almost linearly with the displacement and the sensitivity of the curve is dependent on the concentration of the alcohol solution. For a concentration change of methanol from 0 to 35 % in distilled water, the sensitivity is observed to be increased linearly with the concentration due to the reduction of the refractive index of the solution. The highest sensitivity is obtained at around 0.00002mV/(%). The stability, high sensitivity and simplicity of the sensor make it suitable for chemical, pharmaceutical, biomedical and process control sensing applications. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26124
Heterogeneous anthropomorphic phantoms with realistic dielectric properties for microwave breast imaging experiments
Authors: Mashal Alireza , Gao Fuqiang , Hagness Susan C.
Published: May 2011

We present a technique for fabricating realistic breast phantoms for microwave imaging experiments. Using oil‐in‐gelatin dispersions that mimic breast tissue dielectric properties at microwave frequencies, we constructed four heterogeneous phantoms spanning the full range of volumetric breast densities. We performed CT scans and dielectric properties measurements to characterize each phantom. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26128
Optically transparent RF‐EO aperture with 20:1 bandwidth
Authors: Nahar Niru K. , Chung Jae‐Young , Tzanidis Ioannis , Sertel Kubilay , Volakis John L.
Published: May 2011

We present a printed radio frequency (RF) aperture (with an extraordinary 20:1 bandwidth) using optically transparent conductor (OTC), conformally placed onto a perfectly conducting ground plane. Of importance is that the OTC enables vertical integration of electro‐optical and RF. Multiple RF aperture layers can be used to achieve 1–300 GHz operation. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26129
A compact slot inverted‐F antenna to be embedded in the laptop computer for LTE/WWAN applications
Authors: Hu Chuan‐Ling , Lee Wen‐Feng , Lin Shun‐Tian
Published: May 2011

A slot inverted‐F antenna with multiband operations for long‐term evolution (LTE700/2500) and penta‐band wireless wide area network (WWAN) applications is presented. The antenna fabricated on a direct bond copper Al2O3 substrate consists of multibranch strips and a slot which occupy a compact size of merely 97(L) × 11.2(W) × 0.5(H) mm3 to be easily embedded in the laptop computer as an internal antenna. By properly designing the multibranch inverted‐F antenna, three bands covering 659–973 MHz, 1689–2179 MHz and 2449–2779 MHz for the LTE700, GSM850/900, DCS/PCS/UMTS, and LTE2500 operations are achieved with good radiation efficiencies. Thus, the proposed antenna is well suitable to be embedded in the laptop computer for the LTE and WWAN applications. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26131
Anomalous forerunners in wave propagation interpreted by a typical diffraction integral
Authors: Ranfagni A. , Cacciari I. , Ruggeri R. , Agresti A. , Mignani R. , Ricci A. M. , Petrucci A.
Published: May 2011

By using radar techniques over distances of 16 and 80 m, microwave propagation experiments revealed the presence of anomalous forerunners situated in advanced positions with respect to the main (luminal) peak. These results can be interpreted by a typical diffraction integral, which accounts for the existence of (fast) complex waves, which are usually considered only in the near‐field region, but are still surviving beyond this limit. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26133
A compact, one‐piece, metal‐plate patch PIFA for 2.4‐GHz WLAN operation
Authors: Hong Tzi‐Chieh , Su Saou‐Wen , Chang Fa‐Shian
Published: May 2011

A simple, standalone, one‐piece patch PIFA operating in the 2.4‐GHz WLAN band is introduced. The antenna was first constructed by stamping a rectangular flat plate, which has an area of 10 × 62 mm2, and then bent two times to form a compact patch antenna with dimensions 5 × 10 × 35 mm3. The top patch is of the same width as the antenna ground plane and set 5 mm therein above. The feeding and shorting portions of the antenna are all located on the same, short side of the top patch. This arrangement makes the proposed antenna quite easy to manufacture and also facilitates the feeding‐cable soldering. With a low profile of the design and the use of the coaxial‐line feed, the antenna was further applied to a wireless LCD TV for the antenna operating frequency and radiation performance analyses. Details of the design prototype are discussed in the article. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26134
Numerical modeling of thin‐film bulk acoustic wave resonators using a Crank‐Nicolson finite‐difference time‐domain method
Authors: Wu Dagang , Chen Ji , Liu Ce , Bi Frank
Published: May 2011

In this study, an unconditionally stable finite‐difference time‐domain (FDTD) method implemented with Crank‐Nicolson scheme is presented for the analysis of thin‐film bulk acoustic wave resonators (TFBARs).The proposed approach is unconditionally stable and therefore, the algorithm can significantly reduce the computer processing unit (CPU) time compared to that of the conventional FDTD algorithm. The accuracy and efficiency of the proposed method for calculating resonator frequencies of TFBARs are verified by simulation results. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26135
A fully integrated 3–10‐GHz IR‐UWB CMOS impulse generator
Authors: Li Ju‐Ching , Jung Sungyong , Moon Hyejin
Published: May 2011

This letter presents the design and measurement of a CMOS impulse‐radio ultra‐wideband (UWB) impulse generator using IBM 90‐nm CMOS technology for the application of 3.1–10.6 GHz UWB systems. The impulse generator has a simplex architecture using digital circuits and passive bandpass filter. The measurement results show great consistency with the simulation results. The impulse generator has a center frequency of 5.8 GHz and consumes an average power of 0.9 mW at 200 MHz pulse repetition frequency. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26137
A pattern‐reconfigurable antenna using PIN diodes
Authors: Kang Woong , Lee Seokjae , Kim Kangwook
Published: May 2011

A beam pattern‐reconfigurable antenna has been designed to operate over the 2.4 GHz industrial, scientific, and medical (ISM) band.The proposed antenna is symmetric with respect to the vertical center line and has a pair of PIN diodes as switching elements near the top center of the antenna. The electrical shape of the antenna is a loop with an open wire, which flips symmetrically, depending on the switching states. The width and length of the antenna are chosen such that the gain–bandwidth product is maximized while the antenna operates over the 2.4 GHz band. The antenna is shown to have the ability of beam switching without input impedance variation. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26138
Modified fast multipole algorithm using well‐conditioned electric field integral equation for electromagnetic scattering problem
Authors: Chen H. , Wang L. , Chen R. S.
Published: May 2011

Conventional fast multipole algorithm is one of the most widely used integral equation method for its high efficiency. Unfortunately, it always come across a problem named subwavelength breakdown when the finest group size is smaller than 0.2 wavelength. In this article, singular value decomposition method is used to modify the translation operator of fast multipole algorithm. The finest group size will be smaller without subwavelength breakdown by this method, which leads to much reduction of the memory requirement. Furthermore, the time consumption is also reduced by applying the well‐conditioned electric field integral equation. Numerical results prove the validity and efficiency of this method. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26142
Microstrip‐based segmented coupling reader antenna for near‐field UHF RFID applications
Authors: Li Xiuping , Cao Liang
Published: May 2011

A microstrip‐based segmented coupling reader antenna is proposed for near‐field ultra high frequency radio frequency identification applications. The measured reading distance is 13.5 cm in the air and the measured bandwidth is around 55 MHz (895–950 MHz) under the condition of voltage standing wave ratio less than 2.0, which covers the Federal Communications Commission standard (902–928 MHz) completely. In addition, the simulated far‐field gain is around 4.7 dBi. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26144
Modified compressed block decomposition preconditioner for electromagnetic problems
Authors: Jiang Zhaoneng , Chen Ru‐Shan , Fan Zhenhong , An Yuyuan
Published: May 2011

A modified compressed block decomposition (CBD) preconditioner combined with the multilevel fast multipole algorithm (MLFMA) is proposed for efficiently solving large dense complex linear systems that arise in electromagnetic problems.The modified preconditioner utilizes some improvements to improve the CBD preconditioner which is constructed from the available sparse near‐field matrix. On the basis of the modified preconditioner, an efficient matrix–vector multiplication is implemented. Accordingly, the modified preconditioner is comparable with the unpreconditioned generalized minimal residual algorithm (GMRES) in terms of the number of iterations and the total solution time. Remarkably, the modified preconditioner provides a reduction close to one order of magnitude in both the number of iterations and the total solution time. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26149