bluuebunny/crossref_metadata_2025 huggingface dataset:
Organ‐specific effects of oxygen and carbogen gas inhalation on tissue longitudinal relaxation times
Authors: O'Connor James P.B. , Jackson Alan , Buonaccorsi Giovanni A. , Buckley David L. , Roberts Caleb , Watson Yvonne , Cheung Sue , McGrath Deirdre M. , Naish Josephine H. , Rose Chris J. , Dark Paul M. , Jayson Gordon C. , Parker Geoff J.M.
Published: August 2007

Molecular oxygen has been previously shown to shorten longitudinal relaxation time (T1) in the spleen and renal cortex, but not in the liver or fat. In this study, the magnitude and temporal evolution of this effect were investigated. Medical air, oxygen, and carbogen (95% oxygen/5% CO2) were administered sequentially in 16 healthy volunteers. T1 maps were acquired using spoiled gradient echo sequences (TR = 3.5 ms, TE = 0.9 ms, α = 2°/8°/17°) with six acquisitions on air, 12 on oxygen, 12 on carbogen, and six to 12 back on air. Mean T1 values and change in relaxation rate were compared between each phase of gas inhalation in the liver, spleen, skeletal muscle, renal cortex, and fat by one‐way analysis of variance. Oxygen‐induced T1‐shortening occurred in the liver in fasted subjects (P < 0.001) but not in non‐fasted subjects (P = 0.244). T1‐shortening in spleen and renal cortex (both P < 0.001) were greater than previously reported. Carbogen induced conflicting responses in different organs, suggesting a complex relationship with organ vasculature. Shortening of tissue T1 by oxygen is more pronounced and more complex than previously recognized. The effect may be useful as a biomarker of arterial flow and oxygen delivery to vascular beds. Magn Reson Med 58:490–496, 2007. © 2007 Wiley‐Liss, Inc.
New algorithm for quantifying vascular changes in dynamic contrast‐enhanced MRI independent of absolute T1 values
Authors: Haacke E. Mark , Filleti Cristina L. , Gattu Ramtilak , Ciulla Carlo , Al‐Bashir Areen , Suryanarayanan Krithivasan , Li Meng , Latif Zahid , DelProposto Zach , Sehgal Vivek , Li Tao , Torquato Vidya , Kanaparti Rajesh , Jiang Jing , Neelavalli Jaladhar
Published: August 2007

In this work, we present a new method for predicting changes in tumor vascularity using only one flip angle in dynamic contrast‐enhanced (DCE) imaging. The usual DCE approach finds the tissue initial T1 value T1(0) prior to injection of a contrast agent. We propose finding changes in the tissue contrast agent uptake characteristics pre‐ and postdrug treatment by fixing T1(0). Using both simulations and imaging pre‐ and postadministration of caffeine, we find that the relative change (NR50) in the median of the cumulative distribution (R50) is almost independent of T1(0). Fixing T1(0) leads to a concentration curve c(t) more robust to the presence of noise than calculating T1(0). Consequently, the NR50 for the tumor remains roughly the same as the ideal NR50 when T1(0) is exactly known. Further, variations in eating habits are shown to create significant changes in the R50 response for both liver and muscle. In conclusion, analyzing data with fixed T1(0) leads to a more stable measure of changes in NR50 and does not require knowledge of T1(0). Both caffeine and eating introduce major changes in blood flow that can significantly modify the NR50 and lead to incorrect conclusions regarding drug treatment. Magn Reson Med 58:463–472, 2007. © 2007 Wiley‐Liss, Inc.
Parallel image reconstruction using B‐spline approximation (PROBER)
Authors: Petr Jan , Kybic Jan , Bock Michael , Müller Sven , Hlaváč Václav
Published: August 2007

A new reconstruction method for parallel MRI called PROBER is proposed. The method PROBER works in an image domain similar to methods based on Sensitivity Encoding (SENSE). However, unlike SENSE, which first estimates the spatial sensitivity maps, PROBER approximates the reconstruction coefficients directly by B‐splines. Also, B‐spline coefficients are estimated at once in order to minimize the reconstruction error instead of estimating the reconstruction in each pixel independently (as in SENSE). This makes the method robust to noise in reference images. No presmoothing of reference images is necessary. The number of estimated parameters is reduced, which speeds up the estimation process. PROBER was tested on simulated, phantom, and in vivo data. The results are compared with commercial implementations of the algorithms SENSE and GRAPPA (Generalized Autocalibrating Partially Parallel Acquisitions) in terms of elapsed time and reconstruction quality. The experiments showed that PROBER is faster than GRAPPA and SENSE for images wider than 150 × 150 pixels for comparable reconstruction quality. With more basis functions, PROBER outperforms both SENSE and GRAPPA in reconstruction quality at the cost of slightly increased computational time. Magn Reson Med 58:582–591, 2007. © 2007 Wiley‐Liss, Inc.
Fluctuations in tumor blood perfusion assessed by dynamic contrast‐enhanced MRI
Authors: Brurberg Kjetil G. , Benjaminsen Ilana C. , Dørum Liv M.R. , Rofstad Einar K.
Published: August 2007

Temporal heterogeneity in blood perfusion is a common phenomenon in tumors, but data characterizing the nature of the blood flow fluctuations are sparse. This study investigated the occurrence of blood flow fluctuations in A‐07 melanoma xenografts by using gadopentetate dimeglumine (Gd‐DTPA)‐based dynamic contrast‐enhanced MRI (DCE‐MRI). Each tumor was subjected to two DCE‐MRI acquisitions separated by 1 hour. The data were processed by Kety analysis and resulted in two E · F images (E is the initial extraction fraction of Gd‐DTPA and F is the perfusion) and two λ images (λ is the partition coefficient of Gd‐DTPA) for each tumor. The E · F images were used to determine the changes in blood perfusion arising in the time between the two imaging sequences. The λ images were used to control the reproducibility of the experimental procedure. The study showed that DCE‐MRI with subsequent Kety analysis is a useful method for detection of blood flow fluctuations in A‐07 tumors, and strongly suggested that the peripheral regions of A‐07 tumors are more exposed to temporal changes in blood perfusion than are the central regions. Magn Reson Med 58:473–481, 2007. © 2007 Wiley‐Liss, Inc.
Critical illness myopathy: Further evidence from muscle‐fiber excitability studies of an acquired channelopathy
Authors: Allen David C. , Arunachalam Ramamurthy , Mills Kerry R.
Published: August 2007

Recent studies have demonstrated acquired muscle inexcitability in critical illness myopathy (CIM) and have used direct muscle stimulation (DMS) techniques to distinguish neuropathy from myopathy as a cause of weakness in the critically ill. The mechanisms underlying weakness in CIM are incompletely understood and DMS is only semiquantitative. We report results from a series of 32 patients with CIM and demonstrate significant slowing of muscle‐fiber conduction velocity (MFCV) and muscle‐fiber conduction block during the acute phase of CIM, which correlates with prolonged compound muscle action potential (CMAP) duration, clinical severity, and course. We also used a paired stimulation technique to explore the excitability of individual muscle fibers in vivo. We demonstrate altered muscle‐fiber excitability in CIM patients. Serial studies help define the course of these pathophysiological changes. Parallels are made between CIM and hypokalemic periodic paralysis. Our findings provide further evidence for muscle membrane dysfunction being the principal underlying abnormality in CIM. Muscle Nerve, 2007
Reduced Shh expression in TFF2‐overexpressing lesions of the gastric fundus under hypochlorhydric conditions
Authors: Minegishi Y , Suzuki H , Arakawa M , Fukushima Y , Masaoka T , Ishikawa T , Wright NA , Hibi T
Published: August 2007

Expression of sonic hedgehog (Shh), a morphogen for the gastric fundic glands, is reduced in the atrophic mucosa that develops in association with Helicobacter pylori infection, resulting in impaired differentiation of the fundic gland cells, increased expression of trefoil factor family 2 (TFF2) and the formation of spasmolytic polypeptide (SP)‐expressing metaplasia (SPEM), a preneoplastic lesion. However, it is still unresolved whether H. pylori‐induced inflammation and the resultant reduction in parietal cell number or reduced parietal cell function per se reduces Shh expression. The present study was designed to clarify the expression of Shh and TFF2 in the context of parietal cell dysfunction in the absence of inflammation, using histamine H2 receptor‐knockout (H2R‐null) mice and an acid exposure model. Age‐matched H2R‐null mice and wild‐type (WT) mice were used. The expression of Shh and TFF2 mRNA was quantified by quantitative RT‐PCR. Immunohistochemistry was also performed to detect the expression of Shh, TFF2 and cell markers. To study the effects of acid exposure, HCl solution was administered to the animals. The H2R‐null mice exhibited higher gastric pH, increased TFF2 expression and reduced Shh expression. Impaired mucous neck‐to‐zymogenic cell differentiation was observed in the H2R‐null mice. Furthermore, Shh expression increased in the presence of gastric acid and showed a significant correlation with gastric surface pH. In conclusion, our results suggest that persistent parietal cell dysfunction alone (suppressed gastric acid secretion), in the absence of inflammation or parietal cell loss caused by H. pylori infection, may be sufficient to down‐regulate Shh expression in TFF2‐overexpressing preneoplastic lesions of the gastric fundus. Since exposure to acid restored fundic Shh expression, appropriate gastric acid secretion may play an important role in the morphogen dynamics involved in the maintenance of gastric fundic gland homeostasis. Copyright © 2007 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Prognostic significance of myeloperoxidase expression in childhood acute myeloid leukemia
Authors: Roberson Jessica R. , Onciu Mihaela , Pounds Stanley , Rubnitz Jeffrey E. , Pui Ching‐Hon , Razzouk Bassem I.
Published: August 2007

Background

The percentage of myeloperoxidase (MPO)‐positive blast cells is associated with prognosis in adult acute myeloid leukemia (AML), but this association is unsubstantiated in pediatric AML.

Procedure

We retrospectively compared cytochemical MPO results with outcome in 154 patients younger than 21 years treated on three consecutive institutional protocols for newly diagnosed AML (1987–2001). Patients with FAB M0 and M7 AML (no MPO expression) or M3 AML (100% MPO expression) and Down's syndrome were excluded.

Results

Median MPO expression was higher in FAB M2 subtype than in other subtypes (P < 0.0001) and differed significantly across cytogenetic risk groups (P = 0.002) with highest MPO expression among those with favorable karyotypes. The percentage of MPO‐positive blasts was not significantly associated with the probability of complete remission (P = 0.97), event‐free survival (P = 0.72), or survival (P = 0.76) in multivariate analyses that accounted for age, FAB subtype, presenting WBC count, cytogenetic and protocol treatment risk group. In analysis limited to patients with intermediate‐risk cytogenetics, higher MPO expression appeared to be associated with improved EFS (P = 0.06) but was not associated with remission induction rate (P = 0.16) or overall survival (P = 0.38).

Conclusions

The percentage of MPO‐positive blast cells is related to FAB subtype in pediatric AML but has limited prognostic relevance. Pediatr Blood Cancer 2008;50:542–548. © 2007 Wiley‐Liss, Inc.
Failure to lactate: A possible late effect of cranial radiation
Authors: Johnston Karen , Vowels Marcus , Carroll Susan , Neville Kristen , Cohn Richard
Published: August 2007

We conducted a retrospective review of the lactation experience of female survivors who received 24 Gy cranial radiotherapy as CNS prophylaxis for acute lymphoblastic leukemia in childhood prior to 1982 and who attend the Long‐Term Follow‐Up Clinic at Sydney Children's Hospital, Randwick, Australia. Median time since diagnosis is 28 years (range 25–37 years). Twelve have produced offspring. Ten report minimal or no breast changes during pregnancy and failure to lactate postpartum. All patients remain in remission. These data suggest a high risk of failure of lactation in women treated during childhood with 24 Gy cranial irradiation. Awareness of this possibility can assist in counseling. Pediatr Blood Cancer 2008;50:721–722. © 2007 Wiley‐Liss, Inc.
Clinical and laboratorial prediction of bone marrow involvement in children and adolescents with Hodgkin Lymphoma
Authors: Barros Mário Henrique M. , Zalcberg Ilana R. , Hassan Rocio
Published: August 2007

Background

A risk group (RG) system to predict bone marrow involvement (BMI) based on clinical and laboratory parameters was previously shown to have prognostic value in adult patients with Hodgkin lymphoma (HL). Our aim was to test the applicability of BMI RG in an independent group of childhood and adolescent HL patients.

Procedure

Seventy‐eight HL patients (range 3–18, median 14 years old) were retrospectively studied, including revision of histopathological diagnosis and bilateral BM biopsies. Patients were divided into BMI high‐, standard‐ and low‐RG.

Results

The high‐RG included 29.5% of the patients, the standard‐RG, 32%, and the low‐RG, 38.5%. All the patients in the high‐RG had stage III or IV. The five children (6.4%) with BMI were included in the high‐RG (P = 0.001, χ2 test) and had stage IV (P < 0.00001, χ2 test). The BMI risk group out‐performed the clinico‐pathologic risk assessment in predicting BMI, showing 100% sensitivity, 75% specificity and a positive predictive value of 0.88. Neither BMI nor risk of BMI was statistically associated to age groups (≤14 years old or >14 years old), suggesting that age is not a risk factor for BMI in the pediatric population.

Conclusions

The application of BMI RG score was able to efficiently foresee BMI in a pediatric group of HL patients, adding independent information to clinico‐pathologic BMI risk assessment. Pediatr Blood Cancer 2008;50:765–768. © 2007 Wiley‐Liss, Inc.
Hypoplastic left heart syndrome: attitudes among pediatric residents and nurses towards fetal and neonatal management
Authors: Renella P. , Chang R.‐K. R. , Ferry D. A. , Bart R. D. , Sklansky M. S.
Published: August 2007

Objective

To determine the attitudes of pediatric residents and nurses towards fetal/neonatal management of hypoplastic left heart syndrome (HLHS), and their basis.

Methods

Pediatric residents and nurses from three cardiac centers completed a survey with hypothetical scenarios in which their own fetuses or newborns had HLHS. While Institution A performs many HLHS surgeries, Institution C performs very few.

Results

A total of 43% of residents and 50% of nurses would terminate an affected pregnancy. More experience (4 to 7 years, p = 0.04; >7 years, p = 0.05) and employment at institution C (p = 0.04) predicted termination. Expected better quality of life (QOL) (p = 0.02) and five‐year survival >50% (p = 0.06) predicted not terminating. Postnatally, 48% of residents and 68% of nurses would choose, or seriously consider, comfort care. Marriage (p = 0.04) and more experience (4 to 7 years, p = 0.04; >7 years, p = 0.02) predicted choosing comfort care. Asian/Pacific Islander descent (p = 0.01) and expected 5‐year survival >50% (p = 0.02) predicted choosing surgery.

Conclusions

Approximately one‐half of the pediatric residents and nurses surveyed would choose termination of pregnancy or seriously consider declining neonatal surgery, if their own fetus or infant had HLHS. These attitudes reflect perceptions of long‐term QOL and survival. These attitudes may be of interest to caregivers who care for HLHS patients. Copyright © 2007 John Wiley & Sons, Ltd.
Pregnancy following preimplantation genetic diagnosis of cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL)
Authors: Konialis C. , Hagnefelt B. , Kokkali G. , Pantos C. , Pangalos C.
Published: August 2007

Objective

Presentation of a novel case, involving the design and implementation of preimplantation genetic diagnosis (PGD) for cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL).

Methods

The disease‐causing mutation, c.459C>T (R153C) in exon 4 of the Notch3 gene, was previously identified in the affected father. The family already had a pregnancy termination following prenatal diagnosis and chose to undergo PGD. A PGD protocol was designed to include informative, linked short tandem repeat (STR) markers and an intragenic single nucleotide polymorphism (SNP), coupled to mutation identification. Biopsy was performed at day 3 and blastocysts were transferred on day 5 after fertilization. Standard prenatal diagnosis procedures were employed to confirm the PGD results.

Results

One blastomere was removed at day 3 from each of eight embryos. Detection of the c.459C>TNotch3 mutation, coupled to informative polymorphic markers, unambiguously identified three unaffected embryos. Blastocyst transfer resulted in a singleton pregnancy and subsequent prenatal diagnosis confirmed that the fetus was disease‐free.

Conclusions

Given the dominant, highly penetrant and potentially serious effects of Notch3 mutations, PGD for CADASIL may be considered and implemented as a reproductive option, following proper genetic counseling. Copyright © 2007 John Wiley & Sons, Ltd.
Paroxetine in the first trimester and the prevalence of congenital malformations
Authors: Cole J. Alexander , Ephross Sara A. , Cosmatos Irene S. , Walker Alexander M.
Published: August 2007

Purpose

To refine a preliminary analysis identifying a possibly increased prevalence of malformations among infants born to women exposed to paroxetine in the first trimester.

Methods

This study used data from UnitedHealthcare, a large U.S. insurer, using datasets originally for a study of bupropion in pregnancy. We identified women with a live‐born delivery between January 1995 and September 2004. We classified women according to their first trimester mono‐ or mono/polytherapy exposure to paroxetine and other antidepressants. We confirmed malformation cases by medical record abstraction. We calculated the adjusted odds ratios (AORs) through logistic regression.

Results

For paroxetine, there were 815 infants among 791 women exposed as monotherapy, and 1020 infants among 989 women exposed as mono‐ or polytherapy. For other antidepressants, there were 4198 infants among 4072 women exposed as monotherapy, and 4936 infants among 4767 women exposed as mono‐ or polytherapy. AORs for all congenital malformations associated with paroxetine were 1.89 (95%CI 1.20–2.98) for monotherapy, and 1.76 (95%CI 1.18–2.64) for mono‐ or polytherapy. AORs for cardiovascular malformations associated with paroxetine were 1.46 (95%CI 0.74–2.88) for monotherapy, and 1.68 (95%CI 0.95–2.97) for mono‐ or polytherapy.

Conclusions

These more detailed paroxetine findings confirm previous findings of analyses of these data among women exposed to all types of antidepressants. The present findings are consistent with other recent results suggesting the possibility of a modestly increased occurrence of congenital malformations following first trimester exposure to paroxetine compared to other antidepressants. Copyright © 2007 John Wiley & Sons, Ltd.
Reinforcement sensitivity theory at work: punishment sensitivity as a dispositional source of job‐related stress
Authors: van der Linden Dimitri , Beckers Debby G. J. , Taris Toon W.
Published: August 2007

Gray's reinforcement sensitivity theory (RST) describes two important personality constructs; sensitivity to reward and sensitivity to punishment. In two studies, we examine whether these constructs can be considered dispositions to work stress. Results of Study 1 (N = 105 employees in different occupations) indicated that employees with strong punishment sensitivity reacted more strongly to work stressors than others. This idea was confirmed in a longitudinal design in Study 2. Reward sensitivity was unrelated to stress in both studies. Overall, results strongly support the idea that punishment sensitivity is a dispositional source of work stress. Results further confirm that RST and its derived personality measures can contribute to theorizing about personality–environment interactions in a highly relevant daily setting, namely the working environment. Copyright © 2007 John Wiley & Sons, Ltd.
Tracer diffusion properties of core–shell latex films studied by photoinduced grating relaxation
Authors: Suresh Kattimuttathu I. , Veniaminov Andrei , Bartsch Eckhard
Published: August 2007

This article reports the application of the Photo‐Induced Grating Relaxation technique (also known as Forced Rayleigh Scattering) to investigate the dynamics of films prepared from structured core–shell latex particles via the transport property of the photochromic tracer molecule Aberchrome 540®. The core–shell particles were prepared with a fluoropolymer core (immiscible and impenetrable to the tracer) and a poly(butyl methacrylate) shell. The incompletely dried films (with residual water) manifest their spatial heterogeneity via non‐Fickian behavior (spatial scale‐ dependent apparent diffusion coefficient). The diffusion data was interpreted using the two‐state diffusion model, previously developed to describe the tracer diffusion in latex films without any core–shell structure. In contrast to dry latex films made from homogeneous particles, where one observes Fickian diffusion indicative of a homogeneous polymer film, we find that the lattice of fluoropolymer cores leads to a length scale dependent diffusion coefficient for the tracer. This effect can be interpreted as microscopic evidence for a strain hardening effect due to the presence of a hardened layer of matrix polymer (= shell) surrounding the core, which act as nanofillers. This strain hardening effect could be quantified within the two‐state diffusion model in terms of tracer diffusion coefficients and root mean squared displacements. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 2823–2834, 2007
The impact of gas isotopic exchange on the growth rate and hydrogen (deuterium) bonding within CVD diamond films
Authors: Ternyak O. , Michaelson Sh. , Tkach L. , Akhvlediani R. , Hoffman A.
Published: August 2007

Diamond films were grown by hot filament chemical vapor deposition (HF CVD) technique using isotopic gas mixtures: CH4 + H2 and CD4 + D2 with a constant ratio of 1%:99%. The influence of isotopic exchange on the growth kinetics and film properties was investigated. The microstructure and phase composition of regular and isotopic diamond films have been investigated by high resolution scanning electron microscopy (HR‐SEM) and Raman spectroscopy, respectively. The C–H and C–D vibration modes in the film bulk and surface region were studied by Raman spectroscopy and high resolution electron energy loss spectroscopy (HR‐EELS), correspondingly. It was found, that the exchange of H by D atoms in CH4 and H2 gases reduces the diamond growth rate by a factor of 2.3 and improves the film quality. The microstructure of diamond films of comparable thicknesses was found to be very similar for diamond films grown from two different gas mixtures. The HREEL and Raman spectra of these films show the same C–H/D vibrations modes with isotopic shift. We suggest that the rate‐controlling step in the growth process is the disassociation of C–D or C–H bond on the diamond surface and that the isotopic exchange influences the kinetics of diamond growth, but not its mechanism. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Thermoluminescent properties of CVD diamonds for radiation protection and radiotherapy applications
Authors: Marczewska B. , Tromson D. , Descamps C. , Bilski P. , Schirru F. , Nowak T. , Bogus A.
Published: August 2007

Thermoluminescent properties of intrinsic CVD diamond samples synthesized with oxygen added in the gas phase during crystal growth were investigated. Sensitivity and linearity were evaluated over the 0.2–45 Gy dose range, using Cs‐137 and Co‐60 γ‐ray sources. Extremely high sensitivity was observed at doses exceeding 1 Gy, and poor reproducibility, the signal saturating at doses above 10 Gy. The TL properties of the studied crystals were improved by an annealing procedure (400 °C over 30 minutes) but with a significant decrease of the signal amplitude. The annealed detectors were very sensitive to radiation at doses exceeding 2 Gy and signal saturation was observed at doses above 25 Gy. A “quenching” effect of heating rate on the position and the amplitude of the dosimetric peak was also observed. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Deposition of ZnO inclined c‐axis on silicon and diamond by r.f. magnetron sputtering
Authors: Bensmaine S. , Le Brizoual L. , Elmazria O. , Fundenberger J. J. , Benyoucef B.
Published: August 2007

Suitable deposition conditions yielding to thin zinc oxide (ZnO) films with inclined c‐axis have been determined in this work. These films were deposited on silicon (100) and on the nucleation side of self‐standing diamond substrates. We used r.f. magnetron and a zinc‐oxyde target. We characterized by X‐ray diffraction (XRD) the film texture and by scanning electron microscopy (SEM) the film morphology. XRD has revealed that theses films are polycrystalline in nature having a hexagonal wurtzite crystal structure. We have measured a c‐axis angle of inclination of 45° in the case of ZnO/Diamond sample. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
pH sensitivity of nanocrystalline diamond films
Authors: Christiaens P. , Abouzar M. H. , Poghossian A. , Wagner T. , Bijnens N. , Williams O. A. , Daenen M. , Haenen K. , Douhéret O. , D'Haen J. , Mekhalif Z. , Schöning M. J. , Wagner P.
Published: August 2007

The pH‐sensitive properties of hydrogen‐ and oxygen‐terminated nanocrystalline diamond (NCD) films have been investigated using a field‐effect‐based capacitive electrolyte‐diamond‐insulator‐semiconductor (EDIS) structure as transducer. The NCD thin films (100–500 nm) were grown on p‐Si–SiO2 substrates by microwave plasma‐enhanced chemical vapour deposition. The electrochemical characterisation of EDIS sensors with NCD films of different thicknesses has been performed in buffer solutions of pH 3 to pH 11 by means of capacitance–voltage and constant–capacitance methods. The developed EDIS sensors with O‐terminated NCD surfaces show an average pH‐sensitivity of 38 mV/pH. A slightly smaller pH‐sensitivity of 29–36 mV/pH was observed for the EDIS structure with H‐terminated NCD surfaces. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Fission reactor flux monitors based on single‐crystal CVD diamond films
Authors: Almaviva S. , Marinelli M. , Milani E. , Prestopino G. , Tucciarone A. , Verona C. , Verona‐Rinati G. , Angelone M. , Lattanzi D. , Pillon M. , Rosa R.
Published: August 2007

Diamond based thermal neutron flux monitors have been fabricated using single crystal diamond films, grown by chemical vapour deposition. A 3 μm thick 6LiF layer was thermally evaporated on the detector surface as a converting material for thermal neutron monitoring via the 6Li(n, α) T nuclear reaction. The detectors were tested in a fission nuclear reactor. One of them was positioned 80 cm above the core mid‐plane, where the neutron flux is 2.2 × 109 neutrons/cm2 s at 1 MW resulting in a device count rate of about 150000 cps. Good stability and reproducibility of the device output were proved over the whole reactor power range (up to 1 MW). During the irradiation, several pulse height spectra were recorded, in which both products of the 6Li(n, α) T reaction, e.g. 2.73 MeV tritium and the 2.06 MeV α, were clearly identified, thus excluding a degradation of the detector response. A comparison with a reference fission chamber monitor pointed out a limitation of the adopted readout electronics at high count rates, due to multiple pile‐up processes. However, once this effect is properly accounted for, a good linearity of the diamond flux monitor response is observed as a function of the fission chamber one, as well as an excellent agreement between the temporal behaviour of the two detector response. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Static and transient electrical properties of (111) diamond p–n diodes
Authors: Tavares C. , Muret P. , Koizumi S. , Jomard F.
Published: August 2007

Electrical properties of diamond p–n diodes grown on (111) diamond substrate and processed by reactive ion etching are investigated. The diodes comprise a metallic ohmic contact on the top of a stack n+/n/p/p+/(111)C grown on a monocrystalline diamond substrate and an other ohmic contact on the p+ layer. Boron and phosphorus concentrations are measured by SIMS, the p and n ones being respectively 7 × 1017 and 1 × 1018 cm–3, and compared to the capacitance–voltage response of the diodes, showing an almost complete activation of dopants. Current–voltage I (V) characteristics are measured from ambient temperature up to 872 K. Rectifying factors at ±10 V are close to seven orders of magnitude at ambient temperature, and still above four between 800 K and 872 K. Capacitance detected deep level transient spectroscopy (C‐DLTS) is performed between 400 and 850 K in order to track impurities and defect centres. No majority carrier traps are detected. DLTS spectra appear only when an injection pulse is applied, indicating the presence of minority carrier traps, with concentrations only in the 1015 cm–3 range. Both standard and multi‐exponential transients analysis are performed to extract ionisation energies and capture cross sections. DLTS spectra performed repetitively show unambiguous evolutions after thermal cycling, evidenced by modifications undergone by deep levels appearing at the highest temperatures. These changes are induced by the simultaneous presence of electric field and heating while change does occur neither for deep levels appearing at the lowest temperatures nor for I (V) characteristics. Comparison of these data in two diodes suggests that deepest levels have a bulk origin whereas shallower ones are surface‐related, possibly due to the reactive ion etching process. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
An infrared study of the superconducting diamond
Authors: Lupi S. , Baldassarre L. , Ortolani M. , Calvani P. , Schade U. , Takano Y.
Published: August 2007

When heavily doped with boron, diamond films can become superconducting with critical temperatures Tc well above 4 K. Here, we measure the reflectivity of such a film down to 5 cm–1, by using both conventional radiation sources and Coherent Synchrotron Radiation. We thus determine the electron‐phonon Eliashberg spectral function α2F (ω) and the optical superconducting gap 2Δ. We conclude that superconducting diamond behaves as a “dirty” BCS superconductor. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Time of flight study of high performance CVD diamond detector devices
Authors: Tranchant N. , Nesladek M. , Tromson D. , Remes Z. , Bogdan A. , Bergonzo P.
Published: August 2007

In comparison with polycrystalline diamond, single crystal diamond (SC CVD) offers important advantages for applications to electronics and detection. This is because SC CVD diamond exhibits improved charge transport characteristics, specifically a high drift mobility and an increased charge carrier lifetime. So far, only limited studies have dealt with the measurements of electrical transport parameters in SC diamond and majority of these studies were based on industrial material only. In our study we have investigated the electrical transport properties of PE CVD SC diamond grown using relatively high pressure growth conditions and high deposition growth rates (typically 20 μm/hour) by two independent methods: the laser Time‐of‐Flight (TOF) and the alpha particle TOF techniques. Raman spectroscopy, defect spectroscopy were used to characterize the quality of the samples prepared. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Microscopic diagnostics of DNA molecules on mono‐crystalline diamond
Authors: Rezek Bohuslav , Shin Dongchan , Uetsuka Hiroshi , Nebel Christoph E.
Published: August 2007

The lower central part of the cover picture shows a three‐dimensional representation of DNA molecules covalently attached to single‐crystal diamond as detected by atomic force microscopy (AFM) by Bohuslav Rezek and co‐workers in their Original Paper [1], selected as Editor's Choice for the current issue. DNA molecules were pushed down and scratched away from the diamond by increasing force (0–75 nN) on the AFM cantilever. The upper central part shows a fluorescence microscopy image of the scratched region. On the left, there is a magnified AFM morphology of the DNA surface showing sub‐nanometer structures. On the right, there is a schematic drawing of the DNA molecular chain which was linked to diamond.

The first author of the article is a research team leader and Purkyně Fellow at the Institute of Physics of the Academy of Sciences of the Czech Republic in Prague, where he is working on functional nano‐interfaces of semiconductors and organic materials. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Fabrication of doped nano‐electromechanical systems
Authors: Scheible Dominik V. , Qin Hua , Kim Hyun‐Seok , Blick Robert H.
Published: August 2007

We present a new generation of nano‐electromechanical systems (NEMS), which are realized by doping the semiconductor base material. In contrast to the traditional approach these doped NEMS (D‐NEMS) do not require a metallization layer. This makes them far lighter and hence increases resonance frequency and quality factor. Additionally, D‐NEMS can be tuned from the conductive state into an insulating one. This will enable a host of new device designs, like mechanically tunable pin‐junctions and nanomechanical single electron switches. We demonstrate D‐NEMS fabrication and operation from the intrinsic, to the light, and to the heavy regime of doping. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Negative refractive index in the near‐UV from Au‐coated CuCl nanoparticle superlattices
Authors: Yannopapas Vassilios
Published: August 2007

Nanoparticle superlattices consisting of CuCl spheres coated with a gold (Au) nanoshell are shown to exhibit negative index of refraction in the near‐UV regime. These predictions are based on calculations of the effective refractive index by use of the extended Maxwell–Garnett theory. The results for the refractive index are supplemented by multiple‐scattering calculations of light‐transmittance curves from finite slabs of nanoparticle superlattices. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Computer‐assisted navigation applied to fetal cardiac intervention
Authors: Emery Stephen P. , Kreutzer Jacqueline , Sherman Frederick R. , Fujimoto Kazuro L. , Jaramaz Branislav , Nikou Constantinos , Tobita Kimimasa , Keller Bradley B.
Published: August 2007

Background

Prenatal cardiac interventions (PCI) for human fetal aortic valve (AoV) stenosis can reduce left ventricular hypoplasia and restore ventricular growth and function. However, ‘freehand’ needle delivery from the maternal skin through the uterine wall, fetal chest and ventricular apex to cross the fetal AoV remains technically challenging and time intensive, and is the rate‐limiting step in the procedure.

Methods

We developed a computer‐assisted navigation (CANav) system that tracks the position and orientation of a two‐dimensional (2D) ultrasound image relative to the trajectory of an electromagnetic (EM) embedded needle and stylet. We tested the CANav system in vitro using a water bath phantom, then in vivo using adult rats and pregnant (fetal) sheep.

Results

The CANav system accurately tracked the delivered needle position in both in vitro phantom and adult rat model experiments. We performed 22 PCI attempts with or without CANav in a fetal sheep model. Maternal laparotomy was required to adjust the fetal position in 50% of the procedures. The time required to deliver the needle from the skin into the left ventricle (LV) using CANav was 2.9 ± 1.7 (range 2–7) min (n = 14) vs. 5.5 ± 4.3 (range 1–12) min (n = 8) without CANav (p < 0.05). The time needed to cross the aortic valve once the needle was within the LV was similar with and without CANav (p = 0.19).

Conclusions

CANav reduces the PCI time required to accurately deliver a needle to the fetal heart. Adaptations of this technical approach may be relevant to other congenital cardiac conditions and ultrasound‐guided medical procedures. Copyright © 2007 John Wiley & Sons, Ltd.
Neural networks for real‐time nonlinear control of a variable geometry turbocharged diesel engine
Authors: Omran Rabih , Younes Rafic , Champoussin Jean‐Claude
Published: August 2007

New engines are submitted to emission standards that are becoming more and more restrictive. Diesel engines are typically equipped with variable geometry turbo‐compressor, exhaust gas recirculation system, high‐pressure common rail system and post‐treatment devices in order to meet these legislative requirements. Consequently, the control of diesel engines becomes a very difficult task involving five to 10 control variables that interact with each other and that are highly nonlinear. Until the present day, the control schemes integrated in the engine's controller are all based on static maps identified by steady‐state engine mapping. Afterward, these schemes are adjusted and calibrated in the vehicle using various control techniques in order to assure a better dynamic response of the engine under dynamic load. In this paper, we are interested in developing a mathematical optimization process that searches for the optimal control scheme under static and dynamic operating conditions. Firstly, we suggest modeling the engine and its emissions using mean value models which require limited experiments and are in good agreement with the experimental data. These models are then used in a dynamic optimization process based on the Broyden–Fletcher–Goldfarb–Shanno algorithm in order to find the optimal control scheme of the engine. The results show a reduction of the engine emissions without deteriorating its performance. Finally, we propose a practical control technique based on neural networks in order to apply these control schemes online to the engine. The results are promising. Copyright © 2007 John Wiley & Sons, Ltd.
Global stabilization of uncertain stochastic nonlinear time‐delay systems by output feedback
Authors: Cui Peng , Zhang Chenghui , Zhang Xianfu
Published: August 2007

Constructive control techniques have been proposed for controlling strict feedback (lower triangular form) stochastic nonlinear systems with a time‐varying time delay in the state. The uncertain nonlinearities are assumed to be bounded by polynomial functions of the outputs multiplied by unmeasured states or delayed states. The delay‐independent output feedback controller making the closed‐loop system globally asymptotically stable is explicitly constructed by using a linear dynamic high‐gain observer in combination with a linear dynamic high‐gain controller. A simulation example is given to demonstrate the effectiveness of the proposed design procedure. Copyright © 2007 John Wiley & Sons, Ltd.
Comparing apples with apples: use of limiting environmental differences to match reference and stressor‐exposure sites for bioassessment of streams
Authors: Chessman B. C. , Muschal M. , Royal M. J.
Published: August 2007

Human impacts on freshwater biota are often assessed by comparisons with regional reference sites judged to be free or nearly free from the influence of stressors of concern. These comparisons may involve predictive models that extrapolate from reference‐site data to estimate the biota that would occur at each assessment site in the absence of the stressors. This extrapolation often involves selection or weighting of data from particular reference sites, but it is seldom demonstrated whether this process results in a more accurate, precise and sensitive assessment than would be achieved from comparison with a simple unweighted combination of data from all reference sites, that is a null model. In addition, predictive models often rely on additive combinations of environmental predictor variables, but such combinations may poorly represent the natural control of spatial variation in biological communities by multiple limiting factors. In this paper, we describe a different type of reference‐site approach, based on the concept of limiting environmental differences (LEDs) as natural constraints on biological similarity among sites. In this method, an assessment site is compared with a sub‐set of environmentally matched reference sites selected by application of LED criteria to individual environmental variables. We illustrate this approach by its application to a potentially subtle impact: the effect of water abstraction on fish assemblages in unregulated streams in northeastern New South Wales, Australia. We compared (1) a LED‐based predictive model, (2) a null model and (3) a model based on cluster analysis and multiple discriminant analysis in the style of the widely followed River Invertebrate Prediction and Classification System (RIVPACS). The LED‐based model was about as accurate as the RIVPACS‐type model and the most precise and sensitive of the three, being best able to distinguish sites where fish assemblages departed from reference status. Copyright © 2007 John Wiley & Sons, Ltd.
The Selwyn River of New Zealand: a benchmark system for alluvial plain rivers
Authors: Larned S. T. , Hicks D. M. , Schmidt J. , Davey A. J. H. , Dey K. , Scarsbrook M. , Arscott D. B. , Woods R. A.
Published: August 2007

Most of the world's alluvial plain rivers have undergone hydrological and geomorphical modifications due to water abstraction, dam and levee construction, gravel mining and other human activities. Some of these rivers function as benchmark systems for identifying and quantifying the ecological responses to hydrological and geomorphological changes. Benchmark systems are critical for understanding these responses, for predicting the effects of future changes, and for trialling restoration and mitigation measures. The Selwyn River of New Zealand is a benchmark system for undammed alluvial rivers that are under intense pressure for water abstraction, and are subject to large flow fluctuations.

The Selwyn is a remarkably complex river, and increased understanding of this system will provide insight for understanding and managing other rivers in its class. Hydrological properties that characterize the Selwyn include strong surface water–groundwater interactions, contiguous ephemeral, intermittent, perennial‐losing and perennial‐gaining reaches and an expanding and contracting dry segment that persists for most of the year. The dry segment, in combination with broad spatial variation in aquifer structure and rainfall, cause the upstream (runoff‐fed) and downstream (groundwater‐fed) river sections to function very differently. These sections are also dissimilar in channel morphology; the upstream section has a braided planform, with mobile bars, and abundant islands and remnant channels, and the downstream section has a single, meandering channel, stable bars and no islands. As in many alluvial plain rivers, large floods drive reach‐scale channel evolution.

This paper introduces a long‐term research program that is underway at the Selwyn River, and explores the hydrological and morphological dynamics that characterize the river. We focus on groundwater–surface water interactions, flow‐permanence patterns and flood‐dependent geomorphology. Hydrological and meteorological data are summarized in a conceptual model of relationships between prevailing weather systems, runoff, aquifer recharge and river flow. The physical template described in this paper governs ecological processes such as dispersal, succession and nutrient cycling. A conceptual model is proposed to organize predictions about dispersal in response to changes in hydrological connectivity. Copyright © 2007 John Wiley & Sons, Ltd.
Knowledge structures of prospectors, analyzers, and defenders: content, structure, stability, and performance
Authors: Kabanoff Boris , Brown Shane
Published: August 2007

The managerial cognition perspective argues that managers operating in complex, dynamic environments develop knowledge structures that help them focus their attention, interpretation, and actions. We explore the content and structure of top managers' strategic knowledge structures by measuring differences in the level of attention they give in annual reports to strategic issues and themes that Miles and Snow used to describe their main strategic types. Twenty‐one themes that form seven main factors describing managers' strategic cognition are identified, and these demonstrate reasonable fit with the Miles and Snow model. We show that expert raters can recognize these factors when they read annual reports that contain them. Cluster analysis is then used to identify groups of firms that share similar profiles on these strategic dimensions which are interpreted as examples of cognitive strategic groups. These groups show alignment with Miles and Snow's strategic types, are relatively stable over time, and differ in financial performance. The sample comprises 1,038 listed Australian firms between the years 1992 and 2003. Copyright © 2007 John Wiley & Sons, Ltd.
Frontomaxillary facial angle in fetuses with trisomy 13 at 11 + 0 to 13 + 6 weeks
Authors: Borenstein M. , Persico N. , Dagklis T. , Faros E. , Nicolaides K. H.
Published: August 2007

Objective

To investigate the frontomaxillary facial (FMF) angle in fetuses with trisomy 13 at 11 + 0 to 13 + 6 weeks of gestation.

Methods

A three‐dimensional (3D) volume of the fetal head was obtained before karyotyping at 11 + 0 to 13 + 6 weeks of gestation in 23 fetuses with trisomy 13. The FMF angle, defined as the angle between the upper surface of the maxilla and the frontal bone in a midsagittal view of the fetal face, was measured and compared to the angle in 500 chromosomally normal fetuses.

Results

In 10 of 12 (83.3%) fetuses with trisomy 13 and holoprosencephaly, the FMF angle was above the 95th centile of the normal range. In the 11 fetuses with no holoprosencephaly, the FMF angle was not significantly different from normal. There was no significant difference in the FMF angle between the trisomy 13 fetuses with and without facial cleft.

Conclusions

In fetuses with trisomy 13, the FMF angle at 11 + 0 to 13 + 6 weeks of gestation is increased only in cases with associated holoprosencephaly. Copyright © 2007 ISUOG. Published by John Wiley & Sons, Ltd.
Capacity of multiuser diversity systems with adaptive transmission and different MIMO schemes
Authors: Yang Liang
Published: August 2007

In this paper, we present a comprehensive capacity analysis of the downlink of multiuser diversity (MD) systems with adaptive transmission over Rayleigh fading channels. First, the exact capacity of the single‐input single‐output (SISO) systems with MD and adaptive transmission technique is derived. The optimal power allocation scheme for such a system is shown to be a water‐filling algorithm. Next, we derive the exact closed‐form capacity expressions for different multiple‐input multiple‐output (MIMO) schemes, including the selective combining (SC), maximum ratio combining (MRC) and space‐time block codes (STBC). In order to avoid the cumbersome numerical root finding techniques in solving the optimal cutoff SNR level below which the channel is not used, we also provide the approximate expressions for the cutoff level. For the MD MIMO systems, it is observed that the optimal power allocation strategy is to focus transmit power on a single transmit antenna (e.g. Tx‐MRC/Rx‐MRC scheme) or selecting the best transmit antennas (e.g. Tx‐SC/Rx‐MRC scheme). Copyright © 2007 John Wiley & Sons, Ltd.