bluuebunny/crossref_metadata_2025 huggingface dataset:
Clinical experience of the use of a pharmacological treatment algorithm for major depressive disorder in patients with advanced cancer
Authors: Okamura Masako , Akizuki Nobuya , Nakano Tomohito , Shimizu Ken , Ito Tatsuhiko , Akechi Tatsuo , Uchitomi Yosuke
Published: April 2007

The objective of this study was to describe the applicability and the dropout of the pharmacological treatment algorithm for major depressive disorder in patients with advanced cancer.

Psychiatrists treated major depressive disorder in advanced cancer patients on the basis of the algorithm. For discussing the problems related to the algorithm, we reviewed the reasons for the non‐application of the algorithm and the reasons for dropout of patients within a week of initiation of treatment.

The algorithm was applied in 54 of 59 cases (applicability rate, 92%). The reasons for the non‐application of the algorithm were as follows: the need to add a benzodiazepine to an antidepressant in 4 cases and the need to choose alprazolam despite the depression being moderate in severity, in order to obtain a rapid onset action and reduce anxiety in a patient with short prognosis. Nineteen of the 55 patients dropped out within a week of initiation of treatment based on the algorithm. Delirium was the most frequent reason for dropout.

The applicability rate was high, but several problems were identified, including those related to the combination of antidepressants and benzodiazepines, pharmacological treatment of depression in patients with short prognosis, and delirium due to antidepressants. Copyright © 2007 John Wiley & Sons, Ltd.
Lung tissue mechanics predict lung hypoplasia in a rabbit model for congenital diaphragmatic hernia
Authors: Flemmer Andreas W. , Jani Jacques C. , Bergmann Florian , Muensterer Oliver J. , Gallot Denis , Hajek Kerstin , Sugawara Junichi , Till Holger , Deprest Jan A.
Published: April 2007

Several animal models have been proposed to study the pathophysiology of congenital diaphragmatic hernia (CDH). Surgical induction of CDH in fetal rabbits during the pseudoglandular phase has been shown to induce severe pulmonary hypoplasia, but functional studies in this model are scarce. We aimed to measure neonatal pulmonary impedance and related it to the severity of lung hypoplasia. CDH was surgically created in rabbits at 23 days of gestation. Following cesarean delivery at term (31 days) pups were subjected to measurement of total lung capacity (TLC), lung to body weight ratio (LBWR) and lung impedance by forced oscillation technique (FOT). Airway resistance (Raw), tissue elastance (HL), tissue damping (GL), and hysteresivity (η) (GL/HL) were calculated from impedance data. Twelve CDH fetuses and 15 controls were available for final analysis. LBWR and TLC were significantly lower in the CDH group compared to gestational and age matched controls (P < 0.001). Raw, HL, and GL were significantly increased in CCDH fetuses. η and HL best reflected lung hypoplasia (LBWR) (r2 = 0.42 and 0.43; P = 0.001), indicating a dominant contribution of lung tissue mechanics to CDH‐induced lung hypoplasia. We successfully introduced lung impedance measurement by FOT in neonatal rabbits. Following surgical induction of CDH in the pseudoglandular phase, they have, next to morphological evidence of pulmonary hypoplasia, changes in lung mechanics. Our results for lung tissue mechanics support the concept of delayed pulmonary tissue modeling. We propose to employ functional studies in future experiments when evaluating prenatal interventions aimed at reversing pulmonary hypoplasia. Pediatr Pulmonol. 2007; 42:505–512. © 2007 Wiley‐Liss, Inc.
Predictors of mortality in adults with cystic fibrosis
Authors: Courtney J.M. , Bradley J. , Mccaughan J. , O'connor T.M. , Shortt C. , Bredin C.P. , Bradbury I. , Elborn J.S.
Published: April 2007

Assessment of prognostic indicators in patients with cystic fibrosis (CF) is important. The study's aim was to assess the relative contribution of gender, genetics and microbiology on survival in adults with CF. Adult patients were studied from 1995 to 2005 and data collected included FEV1 (%predicted), body mass index (BMI), genetics, and microbiology. Data was available on 183 patients in 1995. Forty‐five patients died in the subsequent 10 years. Patients who died during the study had lower mean (SD) FEV1 %predicted in 1995 when compared to those remaining alive, 41.5 (15.2)% versus 69.8 (23.2)% predicted, respectively, P < 0.001 and they had lower mean (SD) BMI in 1995, 19.2 (3.3) kg/m2 in comparison to those remaining alive, 20.7 (3.4) kg/m2, P = 0.008. The proportion of patients infected with Pseudomonas aeruginosa and Burkholderia cepacia complex was higher in the group who died during the study compared to those remaining alive, odds ratio 20.9 P < 0.0001 and 7.1 P < 0.0001, respectively. The presence of the ΔF508 homozygous mutation did not alter survival, P = 0.3. Patients infected with either P.aeruginosa or B.cepacia complex had reduced survival compared to those without infection, P = 0.01 and P < 0.0001, respectively. FEV1% (P < 0.0001), infection with P.aeruginosa (P = 0.005) or B.cepacia complex (P = 0.03) were the only significant predictors of mortality. This study demonstrates adults who died were more likely to have worse lung function and be infected with either P.aeruginosa or B.cepacia complex. FEV1% and infection with P.aeruginosa or B.cepacia complex were the most significant predictors of survival in adults with CF. Pediatr Pulmonol. 2007; 42:525–532. © 2007 Wiley‐Liss, Inc.
Cytotoxic T lymphocyte‐associated antigen‐4 gene polymorphisms confer susceptibility to atopic asthma in Korean children
Authors: Sohn Myung Hyun , Kim Seung‐Hyun , Song Tae‐Won , Kim Kyung‐Won , Kim Eun‐Soo , Park Hae‐Sim , Kim Kyu‐Earn
Published: April 2007

Cytotoxic T lymphocyte‐associated antigen‐4 (CTLA‐4) is a negative regulator of T lymphocyte activation. The gene encoding CTLA‐4 is a candidate gene for conferring susceptibility to allergic disease. The purpose of this study was to evaluate the potential effects of CTLA‐4 gene polymorphisms in Korean children on asthma. We genotyped 272 children with atopic asthma, 54 children with nonatopic asthma (NAA), and 254 control children for allelic determinants at two polymorphic sites in the region at positions promoter − 318 C > T and exon 1 + 49 G > A using restriction fragment length polymorphism methods. As a result, allele and genotype frequencies of the CTLA‐4 exon 1 + 49 G > A polymorphism were different to some extent between the atopic asthma children and the controls with P < 0.05, which did not reach statistical significance after the correction of multiple comparisons. In addition, CTLA‐4 + 49 G > A polymorphism was significantly associated with elevated serum IgE levels (P = 0.01). Of the four haplotype, haplotype 1 (C‐G) was only associated with atopic asthma susceptibility after the correction of multiple comparisons (P = 0.01, OR = 0.702, 95% CI = 0.541–0.911). Polymorphisms in the CTLA‐4 gene likely confer susceptibility to atopic asthma in Korean children. Pediatr Pulmonol. 2007; 42:542–547. © 2007 Wiley‐Liss, Inc.
Distribution of intracellular and secreted surfactant during postnatal rat lung development
Authors: Schmiedl Andreas , Vieten Gertrud , Mühlfeld Christian , Bernhard Wolfgang
Published: April 2007

Pulmonary surfactant prevents alveolar collapse via reduction of surface tension. In contrast to human neonates, rats are born with saccular lungs. Therefore, rat lungs serve as a model for investigation of the surfactant system during postnatal alveolar formation. We hypothesized that this process is associated with characteristic structural and biochemical surfactant alterations. We aimed to discriminate changes related to alveolarization from those being either invariable or follow continuous patterns of postnatal changes. Secreted active (mainly tubular myelin (tm)) and inactive (unilamellar vesicles (ulv)) surfactant subtypes as well as intracellular surfactant (lamellar bodies (lb)) in type II pneumocytes (PNII) were quantified before (day (d) 1), during (d 7), at the end of alveolarization (d 14), and after completion of lung maturation (d 42) using electron microscopic methods supplemented by biochemical analyses (phospholipid quantification, immunoblotting for SP‐A). Immunoelectron microscopy determined the localization of surfactant protein A (SP‐A). (1) At d 1 secreted surfactant was increased relative to d 7–42 and then decreased significantly. (2) Air spaces of neonatal lungs comprised lower fractions of tm and increased ulv, which correlated with low SP‐A concentrations in lung lavage fluid (LLF) and increased respiratory rates, respectively. (3) Alveolarization (d 7–14) was associated with decreasing PNII size although volume and sizes of Lb continuously increased. (4) The volume fractions of Lb correlated well with the pool sizes of phospholipids in lavaged lungs. Our study emphasizes differential patterns of developmental changes of the surfactant system relative to postnatal alveolarization. Pediatr Pulmonol. 2007; 42:548–562. © 2007 Wiley‐Liss, Inc.
Cholesterol level of lipid raft microdomains regulates apoptotic cell death in prostate cancer cells through EGFR‐mediated Akt and ERK signal transduction
Authors: Oh Hea Young , Lee Eun Jin , Yoon Sun , Chung Byung Ha , Cho Kang Su , Hong Sung Joon
Published: April 2007

BACKGROUND

Lipid rafts are cholesterol‐enriched microdomains in cell membranes that have been shown to regulate signal transduction. We investigated whether membrane cholesterol could regulate apoptosis and attempted to elucidate the mechanism by which apoptosis is induced in prostate cancer cells.

METHODS

LNCaP cells were exposed to 2‐hydroxyprophyl‐β‐cyclodextrin (HPCD) to deplete membrane cholesterol. Cell viability and apoptosis were evaluated by Celltiter Blue™ Cell Viability assay and ethidium bromide/acridine orange staining. Signal transduction was investigated by immunoblot analysis of cell lysates.

RESULTS

Cell viability was dose dependent inhibited by HPCD and restored by replenishment of cholesterol. HPCD induced apoptotic cell death through down‐regulation of Bcl‐xL and up‐regulation of caspase‐3 and PARP cleavages. HPCD inhibited both EGFR/Akt and EGFR/ERK signal transduction.

CONCLUSIONS

Lipid raft cholesterol regulates apoptotic cell death in prostate cancer cells through EGFR‐mediated Akt and ERK pathways. Prostate 67: 1061–1069, 2007. © 2007 Wiley‐Liss, Inc.
Crystal structure of S. aureus YlaN, an essential leucine rich protein involved in the control of cell shape
Authors: Xu Ling , Sedelnikova Svetlana E. , Baker Patrick J. , Hunt Alison , Errington Jeff , Rice David W.
Published: April 2007

The crystal structure of a conserved leucine rich protein, YlaN, from Staphylococcus aureus has been determined by X‐ray crystallography to 2.3 Å resolution. Whilst the precise function of S. aureus YlaN is unknown its homologue in B. subtilis has been shown to be essential for cell survival and is thought to be involved in controlling cell shape. The structure of S. aureus YlaN provides the first view of its protein family, which reveals that it is a novel homodimer whose subunit architecture is comprised of an antiparallel 3 helix bundle reminiscent of the helical arrangements seen in leucine zipper proteins. Analysis of the pattern of sequence conservation on the structure has led to the identification of two connected solvent exposed patches of conserved residues in each subunit located at one end of but on opposite faces of the molecule. We suggest that YlaN has a binding role in the cell rather than a catalytic function and a search for its ligand is underway to accelerate its exploitation as a target for antibiotic discovery. Proteins 2007. © 2007 Wiley‐Liss, Inc.
Homology modeling and molecular dynamics simulations of the α1 glycine receptor reveals different states of the channel
Authors: Cheng Mary Hongying , Cascio Michael , Coalson Rob D.
Published: April 2007

Homology modeling is used to build initial models of the transmembrane domain of the human α1 glycine receptor (GlyR) based on the most recently published refined structure of nAChR (PDB ID: 2BG9). Six preliminary GlyR models are constructed using two different approaches. In one approach, five different homopentamers are built by symmetric assembly of α1 GlyR subunits using only one of the five unique chains of nAChR as a template. In a second approach, each nAChR subunit serves as a template for an α1 GlyR subunit. All six initial GlyR constructs are then embedded into a hydrated POPC lipid bilayer and subjected to molecular dynamics simulation for at least six nanoseconds. Each model is stable throughout the simulation, and the final models fall into three distinct categories. Homopentameric GlyR bundles using a single α nAChR subunit as a template appear to be in an open conformation. Under an applied external potential, permeation of Cl− ions is observed within several ns in a channel built on an α chain. Model channels built on non‐α chains have a constriction either near the intracellular mouth or more centrally located in the pore domain, both of which may be narrow enough to close the channel and whose locations correspond to putative gates observed in nicotinicoid receptors. The differences between these three general models suggest that channel closure may be effected by either rotation or tangential tilting of TM2. Proteins 2007. © 2007 Wiley‐Liss, Inc.
Oxygen affinity controlled by dynamical distal conformations: The soybean leghemoglobin and the Paramecium caudatum hemoglobin cases
Authors: Martí Marcelo A. , Capece Luciana , Bikiel Damián E. , Falcone Bruno , Estrin Darío A
Published: April 2007

The binding of diatomic ligands, such as O2, NO, and CO, to heme proteins is a process intimately related with their function. In this work, we analyzed by means of a combination of classical Molecular Dynamics (MD) and Hybrid Quantum–Classical (QM/MM) techniques the existence of multiple conformations in the distal site of heme proteins and their influence on oxygen affinity regulation. We considered two representative examples: soybean leghemoglobin (Lba) and Paramecium caudatum truncated hemoglobin (PcHb). The results presented in this work provide a molecular interpretation for the kinetic, structural, and mutational data that cannot be obtained by assuming a single distal conformation. Proteins 2007. © 2007 Wiley‐Liss, Inc.
The efficacy of a petroleum spray oil against Aphis gossypii Glover on cotton. Part 2: Indirect effects of oil deposits
Authors: Najar‐Rodríguez Adriana J , Walter Gimme H , Mensah Robert K
Published: April 2007

The primary mode of action of petroleum spray oils (PSOs) on pest insects is through direct contact. Indirect effects are, however, also possible, and deposits of the oils may influence pest populations by killing insects and/or by influencing their behaviour. The indirect effects of deposits of a new nC24 oil against the cotton aphid, Aphis gossypii Glover, were therefore determined. The effects of oil deposits on the acceptance of cotton as host plant by the aphids were assessed, as well as aphid mortality rates and their success in the establishment of colonies. The efficacy of deposits of a heavier oil (nC27) was also evaluated. Deposits of PSO were toxic to A. gossypii and remained effective until 8 days after spraying. Mortality decreased with time, so that, the older the deposit, the lower was the mortality. Significantly higher aphid mortalities were achieved on younger leaves than on mature ones. Thus, leaf age proved a significant factor in the efficacy of the deposits. Consecutive prophylactic applications (at 9 day intervals) did not have a cumulative effect, and their killing power proved to be independent of one another. Thus, applying the oil prior to aphid infestations would confer only minimal protection. The mortality inflicted by the deposits was not improved by increasing the molecular mass of the oil used (nC27 oil), but the toxic life of the oil deposit was increased. Oil deposits did not deter alates from landing on oil‐sprayed plants. Oil deposits did, however, affect subsequent alate and nymphal survival, and thus the establishment of aphid colonies. The impact that the oils could have on the longer‐term development of aphid populations in the field was thus demonstrated. First‐ and second‐instar nymphs were the most susceptible life stages, with > 50% mortality compared with < 10% for the other stages. These nymphs did not show the typical signs of oil‐induced mortality observed in aphids killed by direct oil applications, which suggests an alternative mode of action to that of the directly applied oil. Anoxia does not seem to be involved in either process, and alternative modes of action of the oil deposits are discussed. The implications of these findings for cotton aphid control are also considered, primarily in relation to the timing and frequency of oil application. Copyright © 2007 Society of Chemical Industry
The efficacy of a petroleum spray oil against Aphis gossypii Glover on cotton. Part 1: Mortality rates and sources of variation
Authors: Najar‐Rodríguez Adriana J , Walter Gimme H , Mensah Robert K
Published: April 2007

Petroleum spray oils (PSOs) kill insect pests on contact, and the composition of modern PSOs is substantially different from the ones introduced earlier. The effects of direct application of a new nC24 PSO on the cotton aphid, Aphis gossypii Glover, were therefore determined. This covered not only aphid mortality rates but also the way in which the oils affected aphid behaviour at the time of contact with the oil. Direct application of the nC24 oil proved to be highly effective in controlling A. gossypii at a range of concentrations between 1 and 10% v/v. The oil killed cotton aphids quickly, with most of the mortality occurring within the first 10 min of spraying. The fast killing action of the oils prevented any behavioural responses by the aphids. Aphids killed by the oils became flaccid and their legs and antennae extended horizontally relative to the body axis. With time, their cuticle became very shiny and began to darken. The quick death of the aphids suggested a contact mode of action of the oils, an interpretation supported by the lack of any negative effect on aphids not initially reached by the oils. However, those aphids not hit by the oils, but that subsequently encountered oil‐treated areas when they moved elsewhere, also died, indicating that the oil deposits are also toxic to the aphids. The mode of action of the oil thus seems to be versatile, and the means by which it kills the aphids may be more complex than anoxia, which is the widely claimed mechanism attributed to PSOs. This oil now needs to be tested for any possible indirect effects on the cotton aphid (e.g. through its host‐plant acceptance behaviour). The implications of the present findings for cotton aphid control and assessment of PSO efficacy in the field are discussed. Copyright © 2007 Society of Chemical Industry
Soft photo structuring of porous silicon in water
Authors: Juan M. , Bouillard J. S. , Plain J. , Bachelot R. , Adam P. M. , Lerondel G. , Royer P.
Published: April 2007

We report on local photo‐induced patterning of porous silicon in water. Scanning probe microscopy images of the sample surface after illumination show that the emission properties as well as the topography are modified according to the interferometric illumination pattern. Local photo‐oxidation is believed to be at the origin of these modifications. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
New porosification of n‐InP and n‐GaAs in acidic liquid ammonia at 223 K: unusual morphologies associated to distinguished electrochemical behaviours
Authors: Gonçalves Anne‐Marie , Santinacci Lionel , Eb Alexandra , David Caroline , Mathieu Charles , Herlem Michel , Etcheberry Arnaud
Published: April 2007

In this paper we report on galvanostatic pore formation on both n‐InP and n‐GaAs in acidic liquid ammonia (223 K). Quantitative analyses by atomic absorption have revealed two different dissolution mechanisms (involving 6 or 8 holes) without secondary reaction. Electrochemical behaviours have also shown diverse evolutions. Potential oscillations were observed onto InP while a constant voltage is measured for GaAs. Distinguished pore morphologies observed by scanning electron microscopy have confirmed the different porosification processes. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Alkaline etching of macroporous silicon
Authors: Lehmann Volker
Published: April 2007

Square pore cross‐sections and pore arrays of high porosity can be produced by subsequent alkaline etching of macroporous silicon membranes. The dependence of pore geometry on etching time, solution temperature and composition is investigated. The produced membranes offer new roads to investigate the formation of pyramidal hillocks during alkaline etching; an effect which is known for half a century, but not understood in detail. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Control of charge carrier density in mesoporous silicon by adsorption of active molecules
Authors: Kashkarov P. K. , Osminkina L. A. , Konstantinova E. A. , Vorontsov A. S. , Pavlikov A. V. , Timoshenko V. Yu.
Published: April 2007

We demonstrate that adsorption of donor‐like and acceptor‐like molecules could be used to control the free charge carrier type and density in mesoporous silicon films. Fourier‐transform infrared spectroscopy and electron paramagnetic resonance technique are used to investigate the free charge carriers and surface defects (Pb‐like centers), respectively, in porous films formed from crystalline Si substrate of different conductivity type and doping level. It is shown that the carrier type (electron or hole) and concentration in mesoporous silicon are depended on (i) molecule partial pressure, (ii) doping level of the substrate; (iii) density of defects‐silicon dangling bonds. The free hole concentration in p‐type mesoporous silicon is found to be changed in the range from 1017 to 3 × 1019 cm–3 by the adsorption of acceptor‐like molecules. The donor‐like molecule adsorption can switch the type of major carriers from holes to electrons. The obtained results are explained by considering the adsorption‐induced formation of surface states in Si nanocrystals assembling mesoporous silicon. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Porous silicon as a cell interface for bone tissue engineering
Authors: Sun Wei , Puzas J. Edward , Sheu Tzong‐Jen , Fauchet Philippe M.
Published: April 2007

A novel cell interface has been constructed on porous silicon. We have demonstrated that nano‐ to macro‐scale porous architectures have promising osteoconductive potentials. Macroporous silicon (pore opening 1–2 µm) is especially favorable for osteoblast adhesion, growth, protein synthesis and mineralization. An electronic/optoelectronic controllable medical implant with both scaffolding and drug delivery functions may be created for orthopaedic tissue engineering with this material. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Integrated inductors on porous silicon
Authors: Contopanagos H. , Nassiopoulou A. G.
Published: April 2007

We examine porous Si as a thick RF‐isolation layer for on‐chip inductors and separate the loss sources that downgrade the Q factors into their material components, namely Si substrate loss and metal types common to standard CMOS technologies. First we validate theoretical designs with measurements in standard 0.18 μm CMOS technology. Then we examine the effect of a porous Si substrate on a fixed metal layout of a 2‐metal optimized inductor design compatible either with 0.18 μm CMOS technology using Aluminum or with 0.13 μm CMOS technology using Copper metallization. For typical on‐chip inductor layouts of (200–300 μm)2, we show that a 50 μm thick porous Si layer produces negligible current distributions inside the underlying lossy Si substrate, compared to the ones without it, which maintain high values throughout a large lateral extent of the die. In Al technology, a fixed inductor layout produces Q ‐factor enhancements of the order of 50%, compared to the case where no porous Si layer is used. In a 0.13 μm‐compatible CMOS technology using Cu on porous Si, the resulting Q ‐factors increase by a factor of 2 and reach values of 30 or more in the 3 GHz frequency range. For porous‐Si‐isolated inductors we compare the effect of metal losses and show that the resulting Q ‐factors scale with the metal conductivity. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Novel microfluidic flow sensor based on a microchannel capped by porous silicon
Authors: Pagonis D. N. , Petropoulos A. , Kaltsas G. , Nassiopoulou A. G. , Tserepi A.
Published: April 2007

This work concerns the fabrication, modeling and characterization of a novel microfluidic flow sensor based on a microchannel capped with a porous silicon membrane, on top of which the sensor active elements are integrated. The microchannel is formed through a two‐step anodization process. In the first step a mesoporous silicon layer is formed on a lithographically defined area, while in the second step a channel is formed underneath the porous layer by electropolishing. The channel is buried into bulk silicon and capped with a free‐standing porous silicon layer, which is co‐planar with the Si substrate. The overall developed process for the formation of the device will be described and simulation and device characterization results will be presented. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The role of quantum confinement and surface chemistry in silicon nanocrystals at the strong confinement regime
Authors: Sa'ar A. , Dovrat M. , Jedrzejewsky J. , Popov I. , Balberg I.
Published: April 2007

Using infrared photo‐induced absorption (PIA) spectroscopy, we have found a remarkable correlation between inter‐sub‐level (ISL) optical transitions and the photoluminescence (PL) from silicon nanocrystals. Our results indicate that the quantized electronic sublevels of the nanocrystals are resonantly coupled to surface vibrational modes via a polarization field produced by coherent longitudinal polar vibrations. The model and the experimental results support our findings that the mechanism responsible for the efficient PL from silicon nanocrystals should be assigned to inhibition of nonradiative channels rather than enhancement of radiative transitions. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Porous surface statistical characterization via fluorescence correlation spectroscopy
Authors: Plain J. , Jaffiol R. , Lerondel G. , Royer P.
Published: April 2007

The characterization of the porosity or of the pore density is a very important issue for porous materials. We report on a new technique allowing a direct measure of the surface pore density. The number of pores on porous silicon substrates has been measured using fluorescence correlation spectroscopy, a technique that is generally applied in solution to study molecules diffusing through a small observation volume. This technique is used to measure the surface density of luminescent pores in a mesoscopic porous silicon layer. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Integrated inductors on porous silicon
Authors: Contopanagos H. , Nassiopoulou A. G.
Published: April 2007

The cover picture illustrates the effective use of a thick porous silicon layer as an integrated micro‐plate for RF isolation on a silicon substrate, proposed by Harry Contopanagos and Androula Nassiopoulou in their Original Paper [1] in the current issue. What is plotted is the magnitude of the current distribution (colour coded from blue (low) to high (red) values) on the metallization and on a screen 50 µm underneath the bottom oxide layer of a 2‐metal integrated CMOS‐compatible inductor on bulk silicon (lower right) and on a 50 µm thick porous silicon layer (upper left) for a frequency of 2.5 GHz.

Inductors were designed in a standard 0.13 µm CMOS technology. Efficient RF isolation is produced by the porous Si layer, as evidenced by the virtual elimination of surface currents relative to the case of standard CMOS, indicating virtually complete substrate shielding by a 50 µm thick porous Si layer for the relevant size scale. The quality factor of the inductor with the use of the porous Si layer is increased by 100%, reaching a maximum value of 33 for the design shown.

The first author of the article is a visiting senior researcher at the Institute of Microelectronics (IMEL), National Center for Scientific Research “Demokritos” (Athens, Greece). His research focuses on electromagnetics and microwave engineering, artificial materials and photonic crystals, wireless front ends, antennas and high‐frequency analog integrated circuits.
An optical excitation study of Ru‐, Rh‐, Re‐ and Os‐doped Bi12SiO20 crystals
Authors: Skorikov V. M. , Milenov T. I. , Egorysheva A. V. , Rafailov P. M. , Dudkina T. D. , Veleva M. N. , Vasil'ev A. Ya. , Gospodinov M. M.
Published: April 2007

We studied the influence of doping with 4d and 5d elements on the optical and photo‐induced properties of Bi12SiO20 (BSO) crystals. Doping with Ru, Rh and Re does not significantly influence BSO absorption spectra as well as photo‐induced absorption and photocurrent in BSO. On the other hand, doping with Os with concentration of 0.0004 mass% increases by more than an order of magnitude the illumination response time, the strength of the photochromic effect and photocurrent, all this being accompanied by only a slight change of the absorption coefficient as compared to undoped BSO. The observed effects are explained in the framework of the Rose model assuming that doping with Os creates deep levels in the gap that act as recombination centers with a very little cross‐section of electron capture. We also studied the kinetic curves of photocurrent increase and decrease in BSO:Os which enabled us to determine the magnitude of the cross‐section of a photon capture at an impurity center. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Mn2+ and band exciton luminescence in ZnMnTe/ZnMgTe quantum well structures
Authors: Agekyan V. F. , Akai I. , Filosofov N. G. , Karasawa T. , Karczewski G. , Serov A. Yu. , Vasiliev N. N.
Published: April 2007

The effect of excitation level on the luminescence of ZnMnTe/ZnMgTe quantum‐well (QW) structures has been studied. We find that result depend strongly on the QW width and manganese concentration. The increasing optical pumping implies a degradation of the Mn2+ intracenter luminescence (IL) due to the interaction of the strongly excited Mn2+ system with the high density of excitons. The spectral and kinetic properties of the IL reveal the contribution of the Mn2+ ions located on the interface and inside the QW as well as the Mn2+ IL decay dependence on the QW width. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Assessing the impact of a care innovation: telecare
Authors: Bayer Steffen , Barlow James , Curry Richard
Published: April 2007

The provision of health and social care for an increasing elderly population is a challenge facing many societies. Telecare, the delivery of health and social care to individuals within the home or wider community, with the support of information and communication technologies, has been advocated as an approach to reduce the rise in the number of elderly people in institutional care and to contain costs. A dynamic model is required to understand the systemic impact of telecare implementation over time. The paper cautions against overoptimistic expectations about the impact of telecare in the short term and emphasises that the benefits for healthcare systems may take a considerable time to be realised. Copyright © 2007 John Wiley & Sons, Ltd.
Small sample performance of tests of homogeneity of odds ratios in K 2 × 2 tables
Authors: Paul S. R. , Donner A.
Published: April 2007

In this note we study, by simulation, small sample performance in terms of size of ten procedures for testing the homogeneity of odds ratios in K 2 × 2 contingency tables. These ten statistics are derived for ‘largestratum’ settings. Our study concerns the behaviour of these statistics for ‘small‐stratum’ settings.
A comparison of sample size methods for the logrank statistic
Authors: Lakatos Edward , Lan K. K. Gordon
Published: April 2007

Several methods are available for sample size calculation for clinical trials when survival curves are to be compared using the logrank statistic. We discuss advantages and disadvantages of some of these methods, and present simulation results under exponential, proportional hazards and non‐proportional hazard situations.
A comparison of several tests for censored paired data
Authors: Woolson Robert F. , O'Gorman Thomas W.
Published: April 2007

This paper reviews several tests for censored paired data and uses Monte Carlo methods to evaluate their sizes and powers. Each of the tests maintains its size. The Akritas test and the paired Prentice–Wilcoxon test are somewhat more powerful than the Gehan statistic or the generalized signed rank test for most of the distributions studied. If the survival times follow an exponential distribution, then the Gehan and the generalized signed rank tests are more powerful against a location shift alternative.
A semi‐bayes approach to the analysis of correlated multiple associations, with an application to an occupational cancer‐mortality study
Authors: Greenland Sander
Published: April 2007

Thomas et al.1 presented the application of empirical‐Bayes methods to the problem of multiple inference in epidemiologic studies. One limitation of their approach, which they noted, was the need to assume exchangeable log relative‐risk parameters, and independent relative‐risk estimates. Numerical integration was also required. Here I generalize their approach to allow for non‐exchangeable parameters and non‐independent estimates. The resulting method is Bayesian in so far as some feature of the prior distribution are specified from prior information, but is empirical Bayes in so far as some explicit parameters in the prior distribution are estimated from the data. Estimation is based on approximations to the posterior distribution; this allows one to implement the approach with standard software packages for matrix algebra. The method is illustrated in an occupational mortality study of 84 exposure‐cancer associations.
Cluster randomization in large public health trials: The importance of antecedent data
Authors: Duffy S. W. , South M. C. , Day N. E.
Published: April 2007

Large‐scale public health trials are often randomized by geographic or administrative clusters, for reasons of financial or organizational exigency. In this paper, we deal with the situation where the dependent variable is a count of events, such as mortality from, or incidence of a given disease. Simulation results show that this design may decrease power by more than 50 per cent. The lost power can largely be replaced by incorporating information on the dependent variable, within clusters, before the start of the trial. The pretrial and trial data can be analysed by negative trinomial models.
How many raters? toward the most reliable diagnostic consensus
Authors: Kraemer Helena Chmura
Published: April 2007

When faced with a decision whether or not to treat a patient, to enter or to withdraw a patient from a clinical trial, or any other such binary decision, based on diagnosis with unsatisfactory reliability, can a consensus diagnosis be used to improve reliability? If so, exactly how? That is the question I address here. I draw comparisons and contrasts between the known results with an interval consensus and those with a binary consensus and suggest tactics for use in a pilot study to answer the above questions.
Adjustments to the mantel–haenszel test for data from stratified multistage surveys
Authors: Weerasekera D. R. , Bennett S.
Published: April 2007

The usual form of the Mantel–Haenszel test statistic assumes independent observations. This is inappropriate for data from a stratified multistage survey. Two alternative adjustments to the test statistic are developed to deal with this: (a) a modification of the effective sample size for each row of each table, using the design effects, extending a method proposed by Donald and Donner for familial aggregation studies; (b) a Taylor series approximation to the variance of the square root of the numerator of the Mantel‐Haenszel statistic. Both methods are evaluated by application to both simulated and real data. The two methods perform equally well, and offer a considerable improvement over the unadjusted test statistic when observations from the same cluster are highly correlated. A simplified adjustment is also considered, as is the need for correction to the variance of the odds ratio estimator.
A note on the presentation of matched case‐control data
Authors: Sasieni Peter
Published: April 2007

Many matched case‐control studies present tables of pooled data ignoring matching. The value of such tables is questioned. If tables of data are included they should certainly not lead to misleading results. Tables that yield consistent estimates in matched studies are considered.
Is the ‘simple carry‐over’ model useful?
Authors: Senn S. J.
Published: April 2007

It is argued that the models usually employed for carry‐over effects in cross‐over trials are not reasonable. The example of a non‐linear dose response for a dose‐finding trial arranged in a Williams square is developed to show that if carry‐over is present to any appreciable degree the usual statistical models provide no guaranteed protection against its effects. It is concluded that the most reasonably defended assumption about carry‐over effects is that no important carry‐over has taken place and that, where this assumption cannot be defended, statistical models provide no satisfactory substitute for it.
Clustering in sparse data and an analysis of rhabdomyosarcoma incidence
Authors: Grimson Roger C. , Aldrich Tim E. , Drane J. Wanzer
Published: April 2007

Time series of epidemiologic events often contain periods of atypically low or high frequency. Correspondingly, for quite rare diseases there occur instances of long vacuous durations interrupted noticeably by periods of some disease activity. A recent community‐based observation of the incidence of rhabdomyosarcoma (RMS), and an investigation of it, yielded sparse data of this general description. We introduce a combinatorial test for patchy time series and apply it to the RMS data. We comment on the prevalent practice of post hoc data analysis of alleged clusters, and on scale effects.
Pre‐natal blood lead levels and learning difficulties in children: An analysis of non‐randomly missing categorical data
Authors: Conaway Mark R. , Waternaux Christine , Allred Elizabeth , Bellinger David , Leviton Alan
Published: April 2007

This paper presents an analysis of categorical variables subject to non‐response. We incorporate the incomplete data into the analysis by modelling the distribution of the variables of interest and the non‐response mechanism. We discuss issues of model selection and interpretation and the effect of discarding incomplete observations. In addition, we describe how to perform all of the computations with standard statistical software. We discuss the problem of incomplete categorical data within the context of a study of the effect of lead exposure on learning difficulties in children. In this study, many of the children are not observed on some of the variables of interest. It is particularly important in this study to incorporate the incomplete data, since there is evidence that non‐response is related to the variables of interest. We reach different conclusions when we incorporate the incomplete data into the analysis than we reach when we discard the incomplete data. We also examine the sensitivity of our conclusions to the choice of a model for the non‐response mechanism.
Applications of crude incidence curves
Authors: Korn Edward L. , Dorey Frederick J.
Published: April 2007

Crude incidence curves display the cumulative number of failures of interest as a function of time. With competing causes of failure, they are distinct from cause‐specific incidence curves that treat secondary types of failures as censored observations. After briefly reviewing their definition and estimation, we present five applications of crude incidence curves to show their utility in a broad range of studies. In some of these applications it is helpful to model survival‐time distributions with use of two different time metameters, for example, time from diagnosis and age of the patient. We describe how one can incorporate published vital statistics into the models when secondary types of failure correspond to common causes of death.
Planned versus attained design in phase II clinical trials
Authors: Green Stephanie J. , Dahlberg Steve
Published: April 2007

The standard phase II trial problem is to decide whether or not to continue the testing of a new agent (or combination). Typically, one tests the null hypothesis Ho:p = po against the alternative HA:p = pA, where p is the probability of response. There is available a variety of two‐stage phase II designs, including optimal designs according to various criteria. Practical considerations in the conduct of multicentre trials, however, make it difficult to follow designs precisely. We investigate several approaches to adapting stopping rules when the attained sample size is not the planned size. We find that a simple approach of testing HA:p = pA at the 0·02 level at the first stage and Ho:p = po at the 0·055 level at the second stage works well across a variety of powers, pos and pAs.
A comment on replication,P‐values and evidence
Authors: Goodman Steven N.
Published: April 2007

It is conventionally thought that a smallp‐value confers high credibility on the observed alternative hypothesis, and that a repetition of the same experiment will have a high probability of resulting again in statistical significance. It is shown that if the observed difference is the true one, the probability of repeating a statistically significant result, the ‘replication probability’, is substantially lower than expected. The reason for this is a mistake that generates other seeming paradoxes: the interpretation of the post‐trialp‐value in the same way as the pre‐trial α error. The replication probability can be used as a frequentist counterpart of Bayesian and likelihood methods to show thatp‐values overstate the evidence against the null hypothesis.
Estimation, reference ranges and goodness of fit for the three‐parameter log‐normal distribution
Authors: Royston Patrick
Published: April 2007

The three‐parameter log‐normal distribution (3PL) is an appropriate model for many of the continuous variables encountered in medicine. It is shown how to obtain different types of estimate and approximate (sometimes conservative) confidence intervals for the parameters of the 3PL and for certain functions of them, particularly in the calculation of reference ranges of clinical measurements. A simple non‐iterative estimate of the shift parameter is described. The Shapiro–Wilk test of non‐normality is modified to allow it to be used for testing for departure from the 3PL. Its power is compared with that of other well‐known tests. The methods are illustrated using several data sets.
Exact unconditional tables for significance testing in the 2 × 2 multinomial trial
Authors: Shuster Jonathan J.
Published: April 2007

This paper presents tables analogous to T‐tables for use in the 2 × 2 multinomial trial, where the continuity corrected Z‐statistic is used to make exact unconditional inference. This is the first solution of a discrete exact unconditional inference problem involving a multivariate nuisance parameter for which no ancillary statistic exists.
Parametric versus non‐parametric methods for estimating cure rates based on censored survival data
Authors: Cantor Alan B. , Shuster Jonathan J.
Published: April 2007

If a patient's failure time is incorrectly recorded as being too early, the correction will lower the plateau of the Kaplan‐Meier curve and, hence, the associated estimated cure rate. Implications of this counter‐intuitive observation are discussed. In addition, a parametric approach, based on the Gompertz distribution, to the problem of cure rate estimation is presented.
Bias in relative odds estimation owing to imprecise measurement of correlated exposures
Authors: Phillips Andrew N. , Smith George Davey
Published: April 2007

A series of graphs is presented that show the estimated degree of bias in logistic coefficient estimates for two correlated continuous exposures measured with imprecision. These graphs indicate that even when the correlation coefficient between the exposure of interest and a correlated exposure is as low as 0·2, imprecision in the measurement of the latter exposure can result in at least as serious bias in the logistic coefficient estimate for the exposure of interest as measurement imprecision in the exposure of interest itself. The implications for the design and interpretation of epidemiological studies are discussed.
Analysis of premature ventricular counts in long term ecg following myocardial infarction
Authors: Laor Arie , Cohen Ayala
Published: April 2007

Frequent and recurrent ventricular premature beats (VPB's) are considered to be associated with a higher risk of sudden cardiac death, particularly for survivors of myocardial infarction (MI). The distribution of VPB's has a large probability mass at zero, and a very heavy right hand tail. In this research, we fitted a model to VPB for patients for which VPB was present. The model was fitted on the basis of a relatively large data set on MI survivors in Israel. The model was fitted by a method which is based on the generalized linear model. This method, which was introduced by Zeger and Liang, is designed for longitudinal data and uses the quasi‐likelihood concept. No specific assumptions are required on the shape of the distribution of the dependent variable. The results indicate that the model fits the data quite well but underestimates the very extreme high values. This research demonstrates the applicability of generalized linear models for longitudinal non‐Gaussian data. Such data often arise in medical studies. The study also points out the distributional properties of VPB counts. In particular, it shows their associations with simple clinical and epidemiological variables, and with certain time periods during the day.
Divergent biases in ecologic and individual‐level studies
Authors: Greenland Sander
Published: April 2007

Several authors have shown that ecologic estimates can be biased by effect modification and misclassification in a different fashion from individual‐level estimates. This paper reviews and discusses ecologic biases induced by model misspecification; confounding; non‐additivity of exposure and covariate effects (effect modification); exposure misclassification; and non‐comparable standardization. Ecologic estimates can be more sensitive to these sources of bias than individual‐level estimates, primarily because ecologic estimates are based on extrapolations to an unobserved conditional (individual‐level) distribution. Because of this sensitivity, one should not rely on a single regression model for an ecologic analysis. Valid ecologic estimates are most feasible when one can obtain accurate estimates of exposure and covariate means in regions with internal exposure homogeneity and mutual covariate comparability; thus, investigators should seek out such regions in the design and analysis of ecologic studies.
An overview of methods for the analysis of longitudinal data
Authors: Zeger Scott L. , Liang Kung‐Yee
Published: April 2007

This paper reviews statistical methods for the analysis of discrete and continuous longitudinal data. The relative merits of longitudinal and cross‐sectional studies are discussed. Three approaches, marginal, transition and random effects models, are presented with emphasis on the distinct interpretations of their coefficients in the discrete data case. We review generalized estimating equations for inferences about marginal models. The ideas are illustrated with analyses of a 2 × 2 crossover trial with binary responses and a randomized longitudinal study with a count outcome.