bluuebunny/crossref_metadata_2025_split huggingface dataset:
Optimization of scan parameters in pulmonary partial pressure oxygen measurement by hyperpolarized 3He MRI
Authors: Yu Jiangsheng , Ishii Masaru , Law Michelle , Woodburn John M. , Emami Kiarash , Kadlecek Stephen , Vahdat Vahid , Guyer Richard A. , Rizi Rahim R. 
Published: November 2007

AbstractThe dependence of hyperpolarized (HP) 3He T1 on local oxygen concentration provides the basis for measuring the partial pressure of oxygen (pO2) and oxygen depletion rate (R) in the lungs. Precise measurements of this type are difficult because the oxygen effect manifests itself through a decay of signal, leading to noisy images at the end of the series. The depolarization caused by RF excitation pulses further complicates the problem. It is therefore important to optimize scan parameters, such as measurement timing and flip angle, to obtain accurate and reproducible measurements. This work presents a new single‐acquisition technique in conjunction with the multiple regression fitting method for data evaluation. Analytical expressions for the measurement uncertainties are derived. A total of four types of single‐acquisition timing schemes are investigated; simulation shows a large uncertainty variation between these schemes (pO2: 7.5–30.2%; R: 47.4–173.7%). A basic procedure for optimizing scan parameters is then described. A phantom experiment was conducted to verify the simulation results. Repeated in vivo measurements with the optimal scheme in a rabbit experiment showed that average variation of global mean is 6.2% for pO2 and 12.0% for R, and that the average variation of percentiles (10th, 25th, 50th, 75th, and 90th) is 8.7% for pO2 and 19.0% for R. Magn Reson Med, 2007. © 2007 Wiley‐Liss, Inc.
Quantitative proton spectroscopic imaging of the neurochemical profile in rat brain with microliter resolution at ultra‐short echo times
Authors: Mlynárik Vladimír , Kohler Ingrid , Gambarota Giulio , Vaslin Anne , Clarke Peter G.H. , Gruetter Rolf 
Published: November 2007

AbstractProton spectroscopy allows the simultaneous quantification of a high number of metabolite concentrations termed the neurochemical profile. The spin echo full intensity acquired localization (SPECIAL) scheme with an echo time of 2.7 ms was used at 9.4T for excitation of a slab parallel to a home‐built quadrature surface coil in conjunction with phase encoding in the two remaining spatial dimensions to yield an effective spatial resolution of 1.7 μL. The absolute concentrations of at least 10 metabolites were calculated from the spectra of individual voxels using LCModel analysis. The calculated concentrations were used for constructing quantitative metabolic maps of the neurochemical profile in normal and pathological rat brain. Summation of individual spectra was used to assess the neurochemical profile of unique brain regions, such as corpus callosum, in rat for the first time. Following focal ischemia in rat pups, imaging the neurochemical profile indicated increased choline groups in the ischemic core and increased glutamine in the penumbra, which is proposed to reflect glutamate excitotoxicity. We conclude that it is feasible to achieve a sensitivity that is sufficient for quantitative mapping of the neurochemical profile at microliter spatial resolution. Magn Reson Med, 2007. © 2007 Wiley‐Liss, Inc.
19F NMR in vivo spectroscopy reflects the effectiveness of perfusion‐enhancing vascular modifiers for improving gemcitabine chemotherapy
Authors: Cron Greg O. , Beghein Nelson , Ansiaux Réginald , Martinive Philippe , Feron Olivier , Gallez Bernard 
Published: November 2007

AbstractNuclear magnetic resonance spectroscopy of fluorine‐19 (19F NMR) has proven useful for evaluating kinetics of fluorinated chemotherapy drugs in tumors in vivo. This work investigated how three perfusion‐enhancing vascular modifiers (BQ123, thalidomide, and Botulinum neurotoxin type A [BoNT‐A]) would affect the chemotherapeutic efficacy of gemcitabine, a fluorinated drug widely used in human cancer treatment. Murine tumor growth experiments demonstrated that only BoNT‐A showed a strong trend to enhance tumor growth inhibition by gemcitabine (1.7 days growth delay, P = 0.052, Student t‐test). In accord with these results, 19F NMR experiments showed that only BoNT‐A increased significantly the uptake of gemcitabine in tumors (50% increase, P = 0.0008, Student t‐test). Further experiments on gemcitabine kinetics (NMR vs time) and distribution (19F MRI) confirmed the uptake‐enhancing properties of BoNT‐A. The results of this study demonstrate that 19F NMR can monitor modulation of the pharmacokinetics of fluorinated chemotherapy drugs in tumors. The results also show that 19F NMR data can give a strong indication of the effectiveness of perfusion‐enhancing vascular modifiers for improving gemcitabine chemotherapy in murine tumors. 19F NMR is a promising tool for preclinical evaluation of such vascular modifiers and may ultimately be used in the clinic to monitor how these modifiers affect chemotherapy. Magn Reson Med, 2007. © 2007 Wiley‐Liss, Inc.
Single‐shot dual‐z‐shimmed sensitivity‐encoded spiral‐in/out imaging for functional MRI with reduced susceptibility artifacts
Authors: Truong Trong‐Kha , Song Allen W. 
Published: November 2007

AbstractBlood oxygenation level‐dependent (BOLD) functional MRI (fMRI) can be severely hampered by signal loss due to susceptibility‐induced static magnetic field (B0) inhomogeneities near air/tissue interfaces. A single‐shot spiral‐in/out sequence with a z‐shim gradient embedded between the two acquisitions was previously proposed to efficiently recover the signal. However, despite promising results, this technique had several limitations, which are addressed here as follows. First, by adding a second z‐shim gradient before the spiral‐in acquisition and optimizing both z‐shim gradients slice‐by‐slice, a significantly more uniform signal recovery can be achieved. Second, by acquiring a B0 map, the optimal z‐shim gradients can be directly, efficiently, and accurately determined for each subject. Third, by complementing the z‐shimming approach with sensitivity encoding (SENSE), the in‐plane spatial resolution can be increased and, hence, susceptibility artifacts further reduced, while maintaining a high temporal resolution for fMRI applications. These advantages are demonstrated in human functional studies. Magn Reson Med, 2007. © 2007 Wiley‐Liss, Inc.
Think tanks in transitional China
Authors: Zhu Xufeng , Xue Lan 
Published: November 2007

AbstractThere is a growing interest in China's think tanks within and outside China. But many questions remain to be answered. How have their roles changed over time? Why are some think tanks more active than others in some areas, but less so in others? To answer such questions, the authors classify China's think tanks according to organisational structure, as a key explanatory concept. A longitudinal review shows that since the 1970s the organisational structure of think tanks has evolved gradually from semi‐official to civilian, with the evolving structures playing different roles and complementing one another. Following analysis of four case studies of China's think tanks, two of which are semi‐official and two of which are civilian, the article draws a picture of the complex relationship between organisational structure, strategy and behaviour of China's think tanks. Copyright © 2007 John Wiley & Sons, Ltd.
Eyes wide shut? Reforming and defusing checks and balances in Argentina
Authors: Santiso Carlos 
Published: November 2007

AbstractHow effective are autonomous audit agencies (AAAs) in curbing corruption and improving fiscal governance in emerging economies? AAAs are autonomous oversight agencies tasked with scrutinising government finances. However, they are not as effective as they could or should be, partly because of the political constraints they face and the political economy context in which they are embedded. This article assesses the performance and trajectory of the Argentine AAA. It suggests that AAAs can have only a limited impact when formal fiscal institutions are undermined by informal practices and undercut by adverse political incentives. It further highlights the limits of radical reform strategies based on the import of exogenous institutional models. This research has important research and policy implications for the reform and strengthening of AAAs in developing countries. Copyright © 2007 John Wiley & Sons, Ltd.
The contribution of international accounting standards to implementing NPM in developing and developed countries
Authors: Navarro Galera Andrés , Rodríguez Bolívar Manuel Pedro 
Published: November 2007

AbstractIn recent years, numerous countries have undertaken administrative reforms to implement New Public Management (NPM) postulates. The implementation of NPM involves new information needs for decision taking by public managers. In this context, public sector accounting plays a key role as an information system for the successful implementation of NPM. The International Federation of Accountants (IFAC) is undertaking an international accounting harmonisation project to establish high‐quality public sector standards to meet the new information requirements under NPM worldwide. This article examines the capability of IFAC accounting measurement bases to meet information needs under NPM postulates, in both developing and developed countries, analysing the differences between these types of countries. The National Accounting Standard Setters (NASS) of 47 countries were asked about the usefulness and viability of Fair Value Accounting (FVA) to implement NPM postulates, especially those concerning improved efficiency, enhanced information transparency and benchmarking analysis. Copyright © 2007 John Wiley & Sons, Ltd.
Cancer, mental disorders, suicidal ideation and attempts in a large community sample
Authors: Rasic Daniel T. , Belik Shay‐Lee , Bolton James M. , Chochinov Harvey M. , Sareen Jitender 
Published: November 2007

AbstractPurpose: To determine the association between cancer diagnosis, mental disorders and suicidal behavior among community dwelling adults.Methods: Data were drawn from the nationally representative Canadian Community Health Survey Cycle 1.2 (N=36 984, response rate 77%, age 15+). Respondents were grouped into three age groups (15–54, 55–74, and 75+ years), and multiple regression analyses were conducted to examine the relationship between cancer and mental disorders: unadjusted and adjusted for sociodemographics, social supports and other mental disorders.Results: Among respondents aged 15–54, cancer was associated with increased odds of major depression (odds ratio [OR]=3.18; 95% confidence interval [CI]: 1.69–5.96), panic attacks (OR=2.15; 95% CI: 1.22–3.77) and any mental disorder. Among respondents aged 55–75, cancer was associated with increased odds of agoraphobia (OR=5.94; 95% CI: 1.68–21.03) and decreased odds of social phobia (OR=0.22; 95% CI: 0.06–0.80). Cancer was not associated with any mental disorder in the 75+ age group. Results persisted after adjustments for the covariates. Suicidal ideation was associated with cancer in the 55–74 age group (OR=5.07; 95% CI: 1.25–20.47) in unadjusted models; however, this relationship became non‐significant when adjusting for the other covariates.Conclusion: Clinicians should consider screening for depression and panic disorder in young, community dwelling patients with cancer. Copyright © 2007 John Wiley & Sons, Ltd.
The impact of cancer and quality of life for long‐term survivors
Authors: Zebrack Brad J. , Yi Jaehee , Petersen Laura , Ganz Patricia A. 
Published: November 2007

AbstractThis study reports on health status and quality of life (QOL) outcomes in long‐term cancer survivors, and potential correlates including cancer type, age at diagnosis, health status, and key sociodemographic variables.Method: One hundred and ninety‐three cancer survivors 5–10 years post‐diagnosis completed a mailed survey assessing physical and mental health status, QOL, post‐traumatic growth, and impact of cancer (IOC).Results: Respondents were comparable to population norms on physical and mental health status. After controlling for sociodemographic and medical status variables, older respondents reported better overall QOL (p=0.004) and mental health (p<0.001), but worse physical health (p=0.04). Survivors reporting low income (p=0.02) and comorbidities (p=0.003) indicated worse physical functioning. A higher negative IOC score was associated with worse physical functioning (p<0.0001), worse mental health (p<0.0001), and lower overall QOL (p<0.0001). A higher positive IOC score was associated with better mental health (p=0.0004) and better overall QOL (p=0.005).Conclusion: Perceptions of how cancer has affected survivors' lives in both positive and negative ways may influence, or be influenced by, their functional abilities and QOL. Copyright © 2007 John Wiley & Sons, Ltd.
Mapping the peptide and protein immune response in the larvae of the fleshfly Sarcophaga bullata
Authors: Ciencialová Alice , Neubauerová Tereza , Šanda Miloslav , Šindelka Radek , Cvačka Josef , Voburka Zdeněk , Buděšínský Miloš , Kašička Václav , Sázelová Petra , Šolínová Veronika , Macková Martina , Koutek Bohumír , Jiráček Jiří 
Published: November 2007

AbstractWe chose the larvae of fleshfly Sarcophaga bullata to map the peptide and protein immune response. The hemolymph of the third‐instar larvae of S. bullata was used for isolation. The larvae were injected with bacterial suspension to induce an antimicrobial response. The hemolymph was separated into crude fractions, which were subdivided by RP‐HPLC, gel electrophoresis, and free‐flow electrophoresis. In several fractions, we determined significant antimicrobial activities against the pathogenic bacteria Escherichia coli, Staphylococcus aureus, or Pseudomonas aeruginosa. Among antimicrobially active compounds we identified dipeptide β‐alanyl‐ L‐tyrosine, protein transferrin, and two variants of peptide sapecin. We also partially characterized two novel antimicrobially active polypeptides; odorant‐binding protein 99b, and a peptide which remains unidentified. Copyright © 2007 European Peptide Society and John Wiley & Sons, Ltd.
Bolometric detection of terahertz radiation from new grating gates device
Authors: Meziani Yahya Moubarak , Hanabe Mitsuhiro , Otsuji Taiichi , Sano Eiichi 
Published: November 2007

AbstractWe report on experimental investigations on room temperature emission of the terahertz radiation from a doubly interdigitated grating gate high‐electron mobility transistor. The device was subjected to 1.5‐mm cw beam laser and the detection was performed using a 4.2 K silicon bolometer. The detected signal is interpreted as a self oscillation of the plasma waves. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Initialization and logic gate operations of nuclear spin qubits using a submicron scale resistively‐detected NMR device
Authors: Ota T. , Yusa G. , Kumada N. , Miyashita S. , Fujisawa T. , Hirayama Y. 
Published: November 2007

AbstractWe demonstrate initialization of nuclear spin qubits using a resistively‐detected nuclear magnetic resonance (NMR) device. In our device, nuclear spins are dynamically polarized in a sub‐micron scale region defined by split gates. The population of each nuclear spin state is estimated from a resistively‐detected NMR spectrum combined with numerical analysis. By applying radio frequency pulses to the polarized nuclear spins, we create two‐qubit effective pure states, which is a crucial step toward NMR quantum computation. We also demonstrate simple logic gate operations such as controlled‐NOT and SWAP gates in this two‐qubit system. The obtained spectra are consistent with numerically calculated ones. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Ballistic electron mean free path of titanylphthalocyanine films grown on GaAs
Authors: Özcan S. , Smoliner J. , Andrews M. , Strasser G. , Dienel T. , Fritz T. 
Published: November 2007

AbstractIn this article, Au/titanylphthalocyanine/n‐GaAs diodes incorporating ultrathin films of the archetypal organic semiconductor titanylphthalocyanine were investigated by ballistic electron emission microscopy/spectroscopy (BEEM/S). BEEM/S measurements were used to determine the transmission of ballistic electrons through titanylphthalocyanine as a function of energy and temperature. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Fourier spectroscopy of decoherence of exciton and their complexes in single InAlAs quantum dots
Authors: Adachi S. , Sasakura H. , Yatsu N. , Kaji R. , Yamada K. , Muto S. , Kumano H. , Suemune I. 
Published: November 2007

AbstractWe report the photon‐correlation Fourier spectroscopy of exciton and exciton complexes in single self‐assembled In0.75Al0.25As/Al0.3Ga0.7As quantum dots. A Michelson interferometer inserted in the photoluminescence path was used to measure the coherent length of the timeaveraged emission of neutral exciton, biexciton, and positive trion. As comparing with their coherence time and their excitation energy dependence, the effects of the exchange interaction and the fluctuation of the surrounding excess charge are discussed. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Excitation power dependence of optically pumped nuclear spin polarizations in single InAlAs QDs
Authors: Kaji R. , Sasakura H. , Adachi S. , Muto S. 
Published: November 2007

AbstractIn a single self‐assembled InAlAs quantum dot, we report the nonlinearity of nuclear spin polarization by optical pumping. Increasing (or decreasing) the excitation power at a particular excitation polarization, nuclear spin polarization shows the abrupt jump (or drop) and a clear hysteresis loop. In addition, the degree of circular polarization of positively charged exciton also exhibits similar bistable behavior and the hysteretic operation has the precise synchronization with the nuclear spin polarization. It suggests that an electron in the positively charged exciton plays a main role to create the abrupt change of the nuclear spin polarization in the observed quantum dot. This abrupt change reveals the sign and magnitude of the electrong‐factors inz‐direction and can be explained by using a simple model calculation. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Inefficiency of intervalley transfer in narrow InGaAs/AlAsSb quantum wells
Authors: Tribuzy C. V.‐B. , Ohser S. , Priegnitz M. , Winnerl S. , Schneider H. , Helm M. , Neuhaus J. , Dekorsy T. , Biermann K. , Künzel H. 
Published: November 2007

AbstractBy using femtosecond pump‐probe spectroscopy we investigate the intersubband relaxation dynamics in narrow InGaAs/AlAsSb quantum wells. A biexponential behavior is an indication of intervalley scattering, which is, however, much slower than known from bulk material. This may be the reason why quantum cascade lasers at wavelengths as short as 3 μm are actually functioning In addition, when pumping slightly below resonance we observe an induced transient absorption, which can be interpreted in terms of electron heating within the first subband. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Electron transport in superlattices for interacting Wannier‐Stark levels
Authors: Reggiani Lino , Guida Angelo , Rosini Marcello 
Published: November 2007

AbstractWe develop a microscopic theory of electron transport in superlattices within the Wannier‐Stark approach by including the interaction among the energy levels pertaining to adjacent quantum wells. The main results are: (i) the interaction among the levels is responsible for a systematic increase of the level energy with respect to the bottom of the quantum well at increasing electric fields; (ii) the interaction is responsible for the onset of a new delocalization of the Wannier‐Stark states at the highest fields associated with the tunneling of electrons between adjacent quantum wells; (iii) with respect to the noninteracting case, at the highest fields the average carrier energy evidences a consistent increase which leads to a significant softening of the negative differential value of both the drift velocity and diffusivity. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Excitation of millimeter‐wave oscillations in InAlAs/InGaAs heterostructures
Authors: Pérez S. , Mateos J. , Pardo D. , González T. 
Published: November 2007

AbstractWe study the origin of strong Terahertz (THz) oscillations taking place in InAlAs/InGaAs slot diodes ‐ base of High Electron Mobility Transistor (HEMT) devices ‐ when bias surpasses 0.5 V. To this end we perform a microscopic analysis of current fluctuations, calculated by means of an ensemble Monte Carlo (MC) simulator. The millimeter and submillimeter waves are caused by the presence of Gunn‐like oscillations whose dynamics is controlled by ballistic Γ valley electrons in the channel. These carriers are capable to reach extremely high velocities due to the influence of degeneracy effects (preventing scattering mechanisms) and the presence of a recessed geometry. The dependence of this process on the recess and recess‐drain lengths is analyzed in order to improve the frequency and magnitude of the oscillations. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Competition between quantum‐confined Stark effect and free‐carrier screening effect in AlGaN/GaN multiple quantum wells
Authors: Fujita T. , Toizumi T. , Nakazato Y. , Tackeuchi A. , Chinone T. , Liang J. H. , Kajikawa M. 
Published: November 2007

AbstractThe competition between the quantum‐confined Stark effect (QCSE) and the free‐carrier screening effect in AlGaN/GaN multiple quantum wells (MQWs) has been investigated by time‐resolved photoluminescence (PL) measurement. AlGaN/GaN MQWs is a promising material for the next‐generation ultraviolet light‐emitting diodes and laser devices. The large changes in the PL energy and the decay time are observed with changing carrier density. We show that the energy shift and the change in decay time are explained well by the free‐carrier screening effect that compensates for the internal electric field. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Theoretical investigation on the detailed mechanism of the OH‐initiated atmospheric photooxidation of o‐xylene
Authors: Huang Mingqiang , Zhang Weijun , Wang Zhenya , Hao Liqing , Zhao Wenwu , Liu Xianyun , Long Bo , Fang Li 
Published: November 2007

AbstractThe reaction mechanism for o‐xylene with OH radical and O2 was studied by density functional theory (DFT) method. The geometries of the reactants, intermediates, transition states, and products were optimized at B3LYP/6‐31G(d,p) level. The corresponding vibration frequencies were calculated at the same level. The single‐point calculations for all the stationary points were carried out at the B3LYP/6‐311++G(2df,2pd) level using the B3LYP/6‐31G(d,p) optimized geometries. Reaction energies for the formation of the aromatic intermediate radicals have been obtained to determine their relative stability and reversibility, and their activation barriers have been analyzed to assess the energetically favorable pathways to propagate the o‐xylene oxidation. The results of the theoretical study indicate that OH addition to o‐xylene forms ipso, meta, and para isomers of o‐xylene‐OH adducts, and the ipso o‐xylene adduct is the most stable among these isomers. Oxygen is expected to add to the o‐xylene‐OH adducts forming o‐xylene peroxy radicals. And subsequent ring closure of the peroxyl radicals to form bicyclic radicals. With relatively low barriers, isomerization of the o‐xylene bicyclic radicals to more stable epoxide radicals likely occurs, competing with O2 addition to form bicyclic peroxy radicals. The study provides thermochemical data for assessment of the photochemical production potential of ozone and formation of toxic products and secondary organic aerosol from o‐xylene photooxidation. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2008