bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of thermal aging on isotactic polypropylene crystallinity
Authors: Law Aaron , Simon Leonardo , Lee‐Sullivan Pearl
Published: January 2008

The effects of elevated temperature aging on the microstructural changes of isotactic polypropylene matrix in a composite have been studied using wide‐angle X‐ray scattering (WAXS) and Fourier‐transform infrared spectroscopy (FTIR). The objective was to quantify small and slow changes in crystallinity due to thermal aging. To minimize sample variability, polypropylene resin was extracted from the molded composite plaque. Changes in crystallinity level and crystalline form were detected using WAXS after prolonged aging at 90 and 140°C. FTIR was utilized to monitor in‐situ crystallinity changes and to detect oxidation products due to thermal decomposition. The level of crystallinity was monitored by changes in the absorbance ratio of A997/A973 and A841/A973; the former ratio was found to be more sensitive for detecting crystallinity changes. Aging at 140°C resulted in oxidation. The kinetics of secondary crystallization for the aging conditions studied was characterized using Avrami plots. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers
GaAs converters for high power densities of laser illumination
Authors: Oliva E. , Dimroth F. , Bett A. W.
Published: January 2008

Photovoltaic power converters can be used to generate electricity directly from laser light. In this paper we report the development of GaAs PV power converters with improved conversion efficiency at high power densities. The incorporation of a lateral conduction layer (LCL) on top of the window layer resulted in a considerable gain in efficiency at high illumination levels. Additional performance improvements were obtained by using a metal electrode grid design and antireflection coating optimised for monochromatic and inhomogeneous laser light. Maximum monochromatic (810 nm) optical‐to‐electrical conversion efficiency of 54·9% at 36·5 W/cm2has been achieved. The characteristics of laser power converters with p/n and n/p polarity are discussed in this paper. Moreover, different materials and doping levels were applied in the LCL. The performance of these different device structures at high laser intensity is presented and discussed. It is shown that the lateral series resistance of the cell has a major impact on the overall device performance. Copyright © 2008 John Wiley & Sons, Ltd.
Optical performance analysis of V‐trough PV concentrators
Authors: Martín N. , Ruiz J. M.
Published: January 2008

This paper proposes a method for the analysis of the optical losses that take place inside PV concentrators, which is useful in the design of such systems. The study is focused in V‐trough concentrators with two‐axis tracking. Those are low concentration systems that use nearly conventional flat PV modules. Optical losses are shown to depend on the cavity angle, the mirrors spectral and angular reflectance and the surfaces dirtiness. Final effective concentration ratio and relative cost should consider all these analysed factors. This will help in the search of the most efficient solution in each case. Copyright © 2008 John Wiley & Sons, Ltd.
Synthesis of poly(isobornyl acrylate) containing copolymers by atom transfer radical polymerization
Authors: Dervaux Bart , Van Camp Wim , Van Renterghem Lieven , Du Prez Filip E.
Published: January 2008

For the first time, a detailed study of the atom transfer radical polymerization of isobornyl acrylate (iBA) is reported. On the basis of these results, well‐defined PiBA‐containing block copolymers were synthesized, focussing on the preparation of amphiphilic poly(acrylic acid) (PAA) containing block copolymers. The precursor monomers 1‐ethoxyethyl acrylate (EEA) as well as tert‐butyl acrylate have been used to synthesize the PAA‐segments of the PiBA‐b‐PAA block copolymers. Finally, the synthesis of “block‐like” copolymers of PiBA and PEEA via a one‐pot procedure was investigated. By optimizing the copper and ligand concentration, and choosing the appropriate solvent, a controlled polymerization behaviour was obtained in all cases, as evidenced by a detailed kinetic analysis, GPC, NMR, and MALDI‐TOF data. Thermogravimetric analysis confirmed the quantitative transformation of the precursor polymer PEEA to the corresponding PAA‐containing copolymers. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1649–1661, 2008
DC Corona Electric Discharges for Air Pollution Control, 2—Ionic Intermediates and Mechanisms of Hydrocarbon Processing
Authors: Marotta Ester , Callea Alessandro , Ren Xianwen , Rea Massimo , Paradisi Cristina
Published: January 2008

A mechanistic study is reported on i‐octane and hexane processing with +DC and −DC corona in air at room temperature and pressure. Current/voltage profiles are matched with the ion analysis data obtained by APCI mass spectrometry. With a −DC corona, the hydrocarbons do not modify the negative ion population with respect to uncontaminated air. In contrast, with a +DC corona many hydrocarbon‐derived positive ions form. O(3P) and •OH were also investigated using chemical probes (ozone formation and CO oxidation, respectively). The results, combined with efficiency and product data, suggest that with −DC corona radical initiation steps occur, whereas with +DC corona ionic reactions prevail.

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Promoter methylation correlates with reduced Smad4 expression in advanced prostate cancer
Authors: Aitchison Alan A. , Veerakumarasivam Abhi , Vias Maria , Kumar Rajeev , Hamdy Freddie C. , Neal David E. , Mills Ian G.
Published: January 2008

BACKGROUND

Transforming growth factor‐β (TGF‐β) is a potent growth inhibitor in a wide range of cell types. A transducer of TGF‐β signaling known as Mothers against decapentaplegic homologue 4 (Smad4) is a known tumor suppressor found on chromosome 18q21.1 and is typically inactivated by deletion or mutation in pancreatic and colorectal cancers. The purpose of the article is to investigate Smad4 expression, gene copy number and methylation status in advanced cases of prostate cancer.

METHODS

We have employed Methylation Specific PCR (MSP) to identify methylation sites within the Smad4 promoter and combined this with quantitative real‐time PCR to look for correlates between methylation status and Smad4 expression and to examine androgen receptor (AR) expression. Bacterial artificial chromosome–comparative genomic hybridization (BAC–CGH) has been used to look for genomic amplifications and deletions which may also contribute to expression changes.

RESULTS

We fail to find evidence of genomic deletions or amplifications affecting the Smad4 locus on chromosome 18 but show a correlation between promoter methylation and the loss of Smad4 expression in the same material. We confirm that the AR locus on the X chromosome is amplified in 30% of the advanced clinical samples and that this correlates with increased transcript levels as previously reported by other groups.

CONCLUSION

This indicates that epigenetic changes affect the expression of the Smad4 protein in prostate cancer and points to methylation of the promoter as a novel marker of and contributor to the disease warranting further study. Prostate 68: 661–674, 2008. © 2008 Wiley‐Liss, Inc.
Total and free PSA kinetics in patients without prostate cancer undergoing radical cystoprostatectomy
Authors: Gregorakis Alkibiades K. , Stefanakis Stefanos , Malovrouvas Dimitrios , Petraki Konstantina , Gourgiotis Dimitrios , Scorilas Andreas
Published: January 2008

Background

Radical cystoprostatectomy and radical prostatectomy are the two major operations where prostate is totally and radically removed. Radical cystoprostatectomy is usually performed in patients with invasive bladder cancer. The aim of the study was to examine Total PSA, Free PSA, and Free/Total Ratio elimination kinetics after radical cystoprostatectomy.

Methods

Serum PSA, Free PSA, and Free/Total Ratio were determined preoperatively, at the time of cystoprostatectomy specimen removal and then at 3, 6, 12, 24, 48, 72, and 168 hr, from seven patients with muscle invasive bladder cancer, who underwent radical cystoprostatectomy. Free and Total PSA concentrations were measured with non‐competitive immunological procedures. The elimination rates and half‐lives of Total, Free PSA and Free/Total Ratio were studied using a nonlinear regression analysis.

Results

Surgical manipulations caused about 1.5‐fold increase of PSA, 5‐fold increase in Free PSA and 3‐fold increase in Free/Total Ratio. PSA and Free PSA followed a biphasic elimination pattern of a rapid exponential (a) phase with a half‐life of 4.27 and 2.14 hr and a terminal, nonexponential (b) phase with a half‐life of 63 and 173.2 hr, respectively. Free/Total PSA Ratio followed, also, a biphasic kinetic pattern of a rapid exponential decline with a half‐life of 3.34 and a terminal non‐exponential increase with a doubling time of 43 hr.

Conclusions

Comparing PSA kinetics after radical cystoprostatectomy with those of radical prostatectomy, it appears that PSA follows the same elimination pattern in both models. In contrast, Free PSA and Free/Total Ratio elimination kinetics' patterns differ between the two surgical models. Prostate 68: 759–765, 2008. © 2008 Wiley‐Liss, Inc.
Volatilisation and competing processes computed for a pesticide applied to plants in a wind tunnel system
Authors: Leistra Minze , Wolters André , van den Berg Frederik
Published: January 2008

BACKGROUND: Volatilisation of pesticides from crop canopies can be an important emission pathway. In addition to pesticide properties, competing processes in the canopy and environmental conditions play a part. A computation model is being developed to simulate the processes, but only some of the input data can be obtained directly from the literature.

RESULTS: Three well‐defined experiments on the volatilisation of radiolabelled parathion‐methyl (as example compound) from plants in a wind tunnel system were simulated with the computation model. Missing parameter values were estimated by calibration against the experimental results. The resulting thickness of the air boundary layer, rate of plant penetation and rate of phototransformation were compared with a diversity of literature data. The sequence of importance of the canopy processes was: volatilisation > plant penetration > phototransformation.

CONCLUSION: Computer simulation of wind tunnel experiments, with radiolabelled pesticide sprayed on plants, yields values for the rate coefficients of processes at the plant surface. As some input data for simulations are not required in the framework of registration procedures, attempts to estimate missing parameter values on the basis of divergent experimental results have to be continued. Copyright © 2008 Society of Chemical Industry
A theoretical investigation on the cycloaddition reaction between azocarbenium ions and nitriles
Authors: Li Zhi‐Ming , Wang Quan‐Rui
Published: January 2008

The 1,3‐dipolar cycloaddition reactions of the cationic 1,3‐dipolarophiles of azocarbenium ion 1 with HCN in the gas phase were examined using the density functional theory, QCISD method (Quadratic configuration interaction using single and double substitutions) and CCSD(T) (Coupled cluster calculations with single and double excitations and a perturbative estimate of triple contributions calculations) calculations. The theoretical results revealed that the reaction takes place via an initial formation of a 1:1 complex of the two reactants, mainly driven by charge interaction, followed by an asynchronous concerted cyclization forming the 3H‐[1,2,4]‐triazolium ion 3, which undergo [1,2]‐H shift to provide the 1H‐[1,2,4]‐triazolium ion 4. The effect of the solvent has been modeled by using the isodensity‐surface polarizable continuum (IPCM) model and the calculation showed that the reaction in CH2Cl2 solution proceeds in a similar manner as in gas phase with only a slight derivation of activation barrier. The substituent effects have also been investigated. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2008
Direct Coprecipitation Route to Monodisperse Dual‐Functionalized Magnetic Iron Oxide Nanocrystals Without Size Selection
Authors: Li Zhen , Tan Bien , Allix Mathieu , Cooper Andrew I. , Rosseinsky Matthew J.
Published: January 2008

Water‐soluble monodisperse superparamagnetic Fe3O4 nanocrystals decorated with two distinct functional groups are prepared in a single‐step procedure by injecting iron precursors into a refluxing aqueous solution of a polymer ligand, trithiol‐terminated poly(methacrylic acid) (PMAA‐PTTM), bearing both carboxylate and thiol functionalities. The ratio of carboxylic acid groups in the polymer‐protecting ligand to the iron precursors plays a key role in determining the particle size and particle size distribution. The surface functionalities of the ligands allow post‐synthesis modification of the materials to produce water‐soluble fluorescent magnetic nanocrystals.
Bone Mineral Density Before and After Surgical Cure of Cushing’s Syndrome Due to Adrenocortical Adenoma: Prospective Study
Authors: Kawamata Akiko , Iihara Masatoshi , Okamoto Takahiro , Obara Takao
Published: January 2008

Osteoporosis is a major complication of Cushing’s syndrome. The aim of the present study was to assess the chronologic effect of surgical cure on bone mineral density (BMD) in patients with Cushing’s syndrome due to adrenal adenoma. BMD was examined in 28 patients before laparoscopic adrenalectomy; 17 patients with reduced BMD were then included in the longitudinal evaluation. BMD was determined using dual energy X‐ray absorptiometry (DXA) before and at 3, 6, 12, 18, and 24 months after adrenalectomy. The prevalence of osteoporosis was 64% (95% confidence interval 44–81%). Preoperative BMD of the lumbar spine in the lateral projection was significantly lower than that of the femoral neck (mean ± SD score: −3.53 ± 0.75 vs. −1.54 ± 0.22, p = 0.003). A significant increase in BMD was observed at 3 months after surgery in the lumbar spine (p = 0.0004). Improvement at both sites was maintained at 24 months after surgery. The postoperative percentage change in BMD of the lumbar spine was significantly higher than that of the femoral neck (mean ± SD 36.7% ± 26.5% vs. 11.2% ± 12.1%, p = 0.01). The change in the seven premenopausal patients was significantly higher than that in the three postmenopausal patients (p = 0.0006). Surgical cure of hypercortisolism provides significant improvement in BMD in patients with Cushing’s syndrome due to adrenal adenoma. The improvement is particularly apparent in the lumbar spine measured in the lateral projection. Premenopausal women are more likely to benefit from surgery in terms of secondary osteoporosis.
The geography of genetics: an analysis of referral patterns to a cancer genetics service
Authors: McDonald Kevin , Iredale Rachel , Higgs Gary
Published: January 2008

This study uses a geographical information system (GIS) and statistical analysis to look for patterns in referrals to a British cancer genetics service. In this case, familial cancers are taken to be those that can develop when an individual inherits DNA mutations that cause an increased risk of cancer. Between 1998 and 2006 the Cancer Genetics Service for Wales received nearly 11,000 referrals for patients resident in Wales and it is the service database recording those referrals which is the subject of this secondary analysis. Using postcodes to match referred patients to areas, deprivation scores were assigned. Referral rates per 10,000 head of population across the 8-year study period by unitary authority are presented, as is information on referrals from primary and secondary care sources by year. Each patient referred has their family history of cancer recorded and is assigned to a risk category; high, medium or average. There are correlations between number of GPs (General Practitioners) in a practice, number of patients referred from a practice, and deprivation as measured by the overall Welsh Index of Multiple Deprivation 2005, such that the two former factors increase as deprivation decreases. Over time there were changes in referral sources, with referrals from primary care overtaking those from secondary care in percentage and absolute terms. There were also changes in the types of cancer referred, risk categories seen and to which centre referrals were made. Referral patterns reveal an inverse relationship between deprivation and health service availability and use.
Transcript‐specific translational regulation in the unfolded protein response of Saccharomyces cerevisiae
Authors: Payne Tom , Hanfrey Colin , Bishop Amy L. , Michael Anthony J. , Avery Simon V. , Archer David B.
Published: January 2008

Accumulation of unfolded proteins in the endoplasmic reticulum (ER) causes stress and induces the unfolded protein response (UPR). Genome‐wide analysis of translational regulation in response to the UPR‐inducing agent dithiothreitol in Saccharomyces cerevisiae is reported. Microarray analysis, confirmed using qRT‐PCR, identified transcript‐specific translational regulation. Transcripts with functions in ribosomal biogenesis and assembly were translationally repressed. In contrast, mRNAs from known UPR genes, encoding the UPR transcription factor Hac1p, the ER‐oxidoreductase Ero1p and the ER‐associated protein degradation (ERAD) protein Der1p, were enriched in polysomal fractions, indicating translational up‐regulation. Splicing of HAC1 mRNA is shown to be required for efficient ribosomal loading.
Antipsychotic drugs alter neuronal development including ALM neuroblast migration and PLM axonal outgrowth in Caenorhabditis elegans
Authors: Donohoe Dallas R. , Weeks Kathrine , Aamodt Eric J. , Dwyer Donard S.
Published: January 2008

Antipsychotic drugs are increasingly being prescribed for children and adolescents, and are used in pregnant women without a clear demonstration of safety in these populations. Global effects of these drugs on neurodevelopment (e.g., decreased brain size) have been reported in rats, but detailed knowledge about neuronal effects and mechanisms of action are lacking. Here we report on the evaluation of a comprehensive panel of antipsychotic drugs in a model organism (Caenorhabditis elegans) that is widely used to study neuronal development. Specifically, we examined the effects of the drugs on neuronal migration and axonal outgrowth in mechanosensory neurons visualized with green fluorescent protein expressed from the mec‐3 promoter. Clozapine, fluphenazine, and haloperidol produced deficits in the development and migration of ALM neurons and axonal outgrowth in PLM neurons. The defects included failure of neuroblasts to migrate to the proper location, and excessive growth of axons past their normal termination point, together with abnormal morphological features of the processes. Although the antipsychotic drugs are potent antagonists of dopamine and serotonin receptors, the neurodevelopmental deficits were not rescued by co‐incubation with serotonin or the dopaminergic agonist, quinpirole. Other antipsychotic drugs, risperidone, aripiprazole, quetiapine, trifluoperazine and olanzapine, also produced modest, but detectable, effects on neuronal development. This is the first report that antipsychotic drugs interfere with neuronal migration and axonal outgrowth in a developing nervous system.
Olfactory ensheathing cells conditioned medium prevented apoptosis induced by 6‐OHDA in PC12 cells through modulation of intrinsic apoptotic pathways
Authors: Feng Lei , Meng Haiwei , Wu Fengxia , Cheng Baohua , He Xiuquan , Wang Xiaohong , Li Zhengping , Liu Shuwei
Published: January 2008

Olfactory ensheathing cells (OECs) express a high level of growth factors which play a very important role as neuronal support. Recent evidence in literatures showed that transplantation of OECs may improve functional restoration in 6‐OHDA‐induced rat model of Parkinson's disease (PD). However, the biological function of various factors released from OECs in Parkinson' disease is still unclear. In this study, we examined the effects of newborn rat OECs conditioned medium (CM) on PC12 cells. Cells treated with 6‐OHDA underwent cytotoxicity and apoptotic death determined by MTT assay and Hoechst 33342/PI staining. OECs CM was able to reduce the cellular damage in PC12 cells. Further investigation results showed that CM inhibited the disruption of mitochondrial transmembrane potential, up‐regulation of Bcl‐2 and down‐regulation of Bax. Taken together, this study indicates that CM has a neuroprotective effect on 6‐OHDA induced apoptosis of PC12 cells, which is through up‐regulation of the Bcl‐2/Bax ratio and protection for mitochondrion.
Iodine intake before and after mandatory iodization in Denmark: results from the Danish Investigation of Iodine Intake and Thyroid Diseases (DanThyr) study
Authors: Rasmussen Lone B. , Carlé Allan , Jørgensen Torben , Knudsen Nils , Laurberg Peter , Pedersen Inge B. , Perrild Hans , Vejbjerg Pernille , Ovesen Lars
Published: January 2008

Iodine deficiency is still common in some European countries. In Denmark an iodine fortification programme was introduced in 1998 and a monitoring programme was established prior to iodization. This study reports the change in urinary iodine excretion caused by fortification and investigates determinants of iodine intake after fortification. Iodine excretion in casual urine samples was assessed in 4649 subjects in 1997–8 and in 3570 comparable subjects in 2004–5 in women 18–22, 25–30, 40–45 and 60–65 years of age and in men 60–65 years of age living in Aalborg (western part of Denmark) or Copenhagen (eastern part of Denmark). These areas had moderate and mild iodine deficiency, respectively, before iodine fortification. All subjects filled in a FFQ and a questionnaire regarding lifestyle factors. Iodine excretion, expressed as the estimated 24 h urinary iodine excretion and as urinary iodine concentration, increased significantly in all age and sex groups. However, the iodine intake was still below the recommended in the youngest age groups in both cities and in women 40–45 years of age living in Aalborg. Intake of milk and salt had strong significant direct associations with iodine excretion (P < 0·001). It is concluded that although the median iodine intake in the whole study population is at the recommended level, some groups still have an intake below the recommended. It is important to have a moderate milk intake to obtain a sufficient iodine intake in Denmark.
Effect of vitamin D supplementation on bone and vitamin D status among Pakistani immigrants in Denmark: a randomised double-blinded placebo-controlled intervention study
Authors: Andersen Rikke , Mølgaard Christian , Skovgaard Lene T. , Brot Christine , Cashman Kevin D. , Jakobsen Jette , Lamberg-Allardt Christel , Ovesen Lars
Published: January 2008

Severe vitamin D deficiency is common among Muslim immigrants. The dose necessary to correct the deficiency and its consequence for bone health are not known for immigrants. The aim was to assess the effect of relatively low dosages of supplemental vitamin D on vitamin D and bone status in Pakistani immigrants. This 1-year-long randomised double-blinded placebo-controlled intervention with vitamin D3 (10 and 20 μg/d) included girls (10·1–14·7 years), women (18·1–52·7 years) and men (17·9–63·5 years) of Pakistani origin living in Denmark. The main endpoints were serum 25-hydroxyvitamin D (S-25OHD), parathyroid hormone, bone turnover markers and bone mass. The study showed that supplementation with 10 and 20 μg vitamin D3 per d increased S-25OHD concentrations similarly in vitamin D-deficient Pakistani women (4-fold), and that 10 μg increased S-25OHD concentrations 2-fold and 20 μg 3-fold in Pakistani men. S-25OHD concentrations increased at 6 months and were stable thereafter. Baseline S-25OHD concentrations tended to be lower in girls and women than in men; females achieved about 46 nmol/l and men 55 nmol/l after supplementation. Serum intact parathyroid hormone concentrations decreased at 6 months, but there was no significant effect of the intervention on bone turnover markers and dual-energy X-ray absorptiometry measurements of the whole body and lumbar spine.
Population genetics ofDrosophila ananassae: genetic differentiation among Indian natural populations at the level of inversion polymorphism
Authors: SINGH PRANVEER , SINGH B. N.
Published: January 2008

The present study, which is one of the longest temporal (two decades) and largest spatial (different parts of India covered) investigations on inversion polymorphism in natural populations ofD. ananassae, was undertaken to understand the dynamics of inversion polymorphism in a broad and comprehensive manner. Forty-five natural populations from different ecogeographic regions of the country (covering the regions from Kashmir to Kanniyakumari and Gujarat to Nagaland) were analysed for chromosomal inversions. All the populations show the presence of the three cosmopolitan inversions, frequencies of which vary among the populations analysed. Simple correlations between frequencies of different inversions and regression analysis of inversion frequencies with latitude, longitude and altitude were insignificant. This reinforces the concept of rigid polymorphism inD. ananassae. Genetic divergence (spatial and temporal) at the level of chromosomal polymorphism among natural populations was calculated. Results show spatial divergence but no temporal divergence. Rigid polymorphic systems ofD. ananassaedid not show long-term directional trends. On the basis of the present study, and after including comparisons with the studies conducted more than two decades ago, the most important conclusion to be drawn is that the three cosmopolitan inversions inD. ananassaesegregate within populations at fairly similar frequencies, and the general geographic pattern has remained constant.
The role of biotic factors in the transmission of free-living endohelminth stages
Authors: THIELTGES D. W. , JENSEN K. T. , POULIN R.
Published: January 2008

The transmission success of free-living larval stages of endohelminths is generally modulated by a variety of abiotic and biotic environmental factors. Whereas the role of abiotic factors (including anthropogenic pollutants) has been in focus in numerous studies and summarized in reviews, the role of biotic factors has received much less attention. Here, we review the existing body of literature from the fields of parasitology and ecology and recognize 6 different types of biotic factors with the potential to alter larval transmission processes. We found that experimental studies generally indicate strong effects of biotic factors, and the latter emerge as potentially important, underestimated determinants in the transmission ecology of free-living endohelminth stages. This implies that biodiversity, in general, should have significant effects on parasite transmission and population dynamics. These effects are likely to interact with natural abiotic factors and anthropogenic pollutants. Investigating the interplay of abiotic and biotic factors will not only be crucial for a thorough understanding of parasite transmission processes, but will also be a prerequisite to anticipate the effects of climate and other global changes on helminth parasites and their host communities.
THE IMPOSSIBILITY OF CONSISTENT DISCRIMINATION BETWEEN I(0) AND I(1) PROCESSES
Authors: MÜller Ulrich K.
Published: January 2008

An I(0) process is commonly defined as a process that satisfies a functional central limit theorem, i.e., whose scaled partial sums converge weakly to a Wiener process, and an I(1) process as a process whose first differences are I(0). This paper establishes that with this definition, it is impossible to consistently discriminate between I(0) and I(1) processes. At the same time, on a more constructive note, there exist consistent unit root tests and also nontrivial inconsistent stationarity tests with correct asymptotic size.
MULTIVARIATE AUTOREGRESSION OF ORDER ONE WITH INFINITE VARIANCE INNOVATIONS
Authors: Zarepour M. , Roknossadati S.M.
Published: January 2008

We consider the limiting behavior of a vector autoregressive model of order one (VAR(1)) with independent and identically distributed (i.i.d.) innovations vector with dependent components in the domain of attraction of a multivariate stable law with possibly different indices of stability. It is shown that in some cases the ordinary least squares (OLS) estimates are inconsistent. This inconsistency basically originates from the fact that each coordinate of the partial sum processes of dependent i.i.d. vectors of innovations in the domain of attraction of stable laws needs a different normalizer to converge to a limiting process. It is also revealed that certain M-estimates, with some regularity conditions, as an appropriate alternative, not only resolve inconsistency of the OLS estimates but also give higher consistency rates in all cases.
IMPLEMENTING INTERNATIONAL MONETARY COOPERATION THROUGH INFLATION TARGETING
Authors: BENIGNO GIANLUCA , BENIGNO PIERPAOLO
Published: January 2008

This paper presents a two-country dynamic general equilibrium model with imperfect competition and nominal price rigidities in which productivity shocks coexist with markup shocks. After analyzing the features of the optimal cooperative solution, we show that this allocation can be implemented in a strategic context through inflation-targeting regimes. Under these regimes, each monetary authority minimizes a quadratic loss function that targets only domestic targets, namely, GDP inflation and the output gap.
Schwerpunktthema: Medikamentöse Behandlung des Morbus Parkinson mit Demenz und anderen neuropsychiatrischen Störungen
Authors: Mollenhauer Brit , Wenzel Sascha , Trenkwalder Claudia
Published: January 2008

Zusammenfassung. Neuropsychiatrische Symptome betreffen mehr als die Hälfte der Patienten mit einem M. Parkinson. In den vergangenen Jahrzehnten eher vernachlässigt, bestimmen diese nicht-motorischen Symptome wie Demenz, Depression und Halluzinationen die Lebensqualität der Betroffenen und ihrer Angehörigen mehr als andere Symptome des Morbus Parkinson. Therapeutische Optionen sind durch die Interaktion mit dem dopaminergen System und der Beteiligung anderer Neurotransmitter-Systeme teilweise erschwert. Für die klinisch notwendige, oft komplexe Behandlung von Parkinson-Patienten mit Demenz und Halluzinationen oder wahnhaften Störungen sind bisher keine kontrollierten Therapiestudien verfügbar und somit sind die meisten medikamentösen Therapien für neuropsychiatrische Probleme bei Morbus Parkinson nicht zugelassen und “off-label”. Wir stellen die aktuell relevante Therapiepraxis für die häufigsten neuropsychiatrischen Symptome bei Morbus Parkinson vor.
Themenschwerpunkt: Schlaf- und Beruhigungsmittel im Alter
Authors: Wolter Dirk K.
Published: January 2008

Zusammenfassung. Schlaf- und Beruhigungsmittel werden von alten Menschen häufiger eingenommen als von jüngeren, Frauen überwiegen. Benzodiazepine und verwandte Substanzen haben hier nach wie vor die größte Bedeutung, obwohl ein Rückgang der Verordnungshäufigkeit zu beobachten ist. In Deutschland werden diese Substanzen zunehmend auf Privatrezept verschrieben, so dass die Krankenkassendaten das Ausmaß des Benzodiazepin-Konsums unterschätzen bzw. den Verordnungsrückgang überschätzen. Benzodiazepine sind zwar akuttoxikologisch sehr harmlose Medikamente, bei chronischer Einnahme sind jedoch schleichende Intoxikationen möglich, die zu gefährlichen Folgen (Stürze, kognitive Beeinträchtigung) und zu diagnostischen Fehlschlüssen (Depression, Demenz) führen können. Deshalb sollten - wenn überhaupt - im Alter nur solche Benzodiazepine eingesetzt werden, die nicht verzögert eliminiert werden (d. h. Lorazepam, Oxazepam und Temazepam). Auch Nicht-BZD, freiverkäufliche Tranquilizer und Phytopharmaka sind keinesfalls harmlos. Von einer Niedrigdosis-Abhängigkeit ist bei 40-50 % der Benzodiazepin-Dauerkonsumenten auszugehen. Entzugssymptome können sehr vielgestaltig sein. Eine defätistische Haltung ist nicht angebracht, das Alter stellt keinen Hinderungsgrund für eine Entzugsbehandlung dar. Der Entzug sollte immer fraktioniert durchgeführt werden, eine medikamentöse Unterstützung ist oft erforderlich. Unerlässlich sind eine gute Arzt-Patient-Beziehung, ausreichende Informationen und ein klarer Plan für den Patienten, dann ist der Entzug auch im hausärztlichen Setting mit Gewinn für die Patienten und ohne Einbußen an Lebensqualität möglich. Falls ein kompletter Entzug nicht möglich ist, stellt auch die Dosisreduktion bzw. die Umstellung auf eine für alte Menschen geeignete Substanz einen Erfolg dar.
Themenschwerpunkt: Probleme der Pharmakotherapie bei der Demenz mit Lewy-Körperchen
Authors: Drach Lutz M.
Published: January 2008

Zusammenfassung: Bei der Demenz mit Lewy-Körperchen (DLK) stellen vorwiegend optische Halluzinationen und Wahn wichtige Items der internationalen klinischen Diagnosekriterien dar. Bei einer Behandlung dieser Symptome mit konventionellen hoch- und niederpotenten Neuroleptika treten aber sehr häufig schwere Nebenwirkungen auf. Die am besten untersuchte Alternative zu Neuroleptika ist die Behandlung dieser nicht-kognitiven Symptome mit Cholinesterasehemmern. Wenn diese aber kontraindiziert sind, nicht vertragen werden oder nicht ausreichend wirken, ist Clozapin, langsam eindosiert und in niedrigen Dosen, ebenso wie bei Psychosen im Verlauf eines M. Parkinson auch bei der DLK wirksam, erfordert aber besondere Vorsichtsmaßnahmen. Offene Studien weisen bei Quetiapin auf Wirksamkeit und Verträglichkeit bei DLK hin. Fallberichte sprechen für die Wirksamkeit einer Quetiapin-Augmentierung bei psychotischen Symptomen der DLK, wenn Cholinesterase-Hemmer alleine nicht ausreichend wirken. Da DLK-Patienten offenbar schlechter auf Antiparkinsonika ansprechen als Parkinson-Patienten und Antiparkinsonika häufiger zu einer Zunahme von Halluzinationen und Wahn führen, sollte deren Einsatz mit Zurückhaltung erfolgen und sich auf L-Dopa beschränken.
Themenschwerpunkt: Die Therapie nicht-kognitiver Störungen bei Demenzkranken mit Neuroleptika
Authors: Ibach Bernd
Published: January 2008

Zusammenfassung: Der vorliegende Artikel diskutiert den potenziellen Nutzen und die Risiken einer neuroleptischen Behandlung von neuropsychiatrischen Symptomen bei Patienten mit Demenz. Verhaltensauffälligkeiten und psychosenahe Phänomene sind während des gesamten Krankheitsverlaufs hoch prävalent und belasten sowohl die Patienten als auch deren Angehörige. Die individuelle Berücksichtigung von Komorbiditäten und einer in der Regel vorhandenen Komedikation sind ebenso wie eine Symptomanalyse bereits vor Beginn einer neuroleptischen Therapie unentbehrlich. Neuroleptika gehören zu den bestuntersuchten Psychopharmaka überhaupt, verfügen über unterschiedliche pharmakologische Profile und werden sehr oft bei älteren Menschen verordnet. Neuere Studienergebnisse machen deutlich, dass Neuroleptika zwar wirksam sind, deren Anwendung jedoch aufgrund ihrer Nebenwirkungsprofile auf Patienten mit schweren klinischen Symptomen beschränkt bleiben sollte.
Therapie der frontotemporalen Demenz
Authors: Perneczky Robert
Published: January 2008

Zusammenfassung. Die frontotemporale Demenz ist nach der Alzheimer-Krankheit die zweithäufigste Ursache einer präsenilen Demenz. Die FTD ist vor allem durch einen schleichenden Beginn, einen progredienten Verlauf und eine frühe Veränderung des Verhaltens gekennzeichnet. Daneben treten Symptome wie Antriebsmangel, Agitation, stereotypes Verhalten, kognitive Beeinträchtigung und Sprachstörungen auf. Über die Therapie der FTD gibt es bisher nur wenige systematische Studien, die jedoch darauf hindeuten, dass vor allem selektive Serotonin-Wiederaufnahme-Hemmer (so genannte SSRI) bei Verhaltensstörungen wirksam sind. Außerdem ist ein individuell abgestimmtes nichtmedikamentöses Vorgehen sinnvoll, das beispielsweise der Antriebssteigerung oder der Verminderung aggressiver Handlungstendenzen dienen soll.
Therapie des Apathie-Syndroms bei Alzheimer-Demenz
Authors: Fellgiebel Andreas , Scheurich Armin
Published: January 2008

Zusammenfassung: Das Apathie-Syndrom lässt sich auffassen als ein Mangel an selbst-initiiertem Verhalten (motorisch, sprachlich, kognitiv, affektiv). Apathie stellt das häufigste neuropsychiatrische Symptom der Alzheimer-Demenz dar und kann in Verbindung gebracht werden mit stärker beeinträchtigter Alltagsfunktion, rascherer Progredienz des kognitiven Abbaus und deutlicher reduzierter Lebensqualität der betreuenden Angehörigen. Trotz weitestgehend fehlender Evidenzbasierung gibt es ein Reihe therapeutischer Optionen, die in der vorliegenden Übersichtsarbeit zusammengefasst und bewertet werden. Nach Ausschluss eines depressiven Syndroms stehen hierbei die Unterstützung der Betreuenden durch Psychoedukation sowie individualisiertes verhaltenstherapeutisch orientiertes Patientenmanagement im Vordergrund. Psychopharmakologisch sollten die zugelassenen Antidementiva (Cholinesterase-Hemmer und/oder Memantine) eingesetzt werden, da diese die Wahrscheinlichkeit des Auftretens und die Ausprägung einer Apathie reduzieren. Für den Einsatz aktivierender Psychopharmaka wie Methylphenidat, Modafinil, Amantadin, Bupropion oder anderer dopaminerger Substanzen liegen gegenwärtig nur sehr begrenzte, z. T. nur kasuistische empirische Daten vor. Zusammenfassend empfehlen die Autoren eine kombinierte Behandlung mit Verhaltenstherapie plus Antidementivum (Cholinesterase-Hemmer und/ oder Memantine).
Ressourcenpriming
Authors: Flückiger Christoph , Frischknecht Eveline , Wüsten Günther , Lutz Wolfgang
Published: January 2008

Zusammenfassung. Durch experimentelle und korrelative Studien untermauert, kann die unmittelbare Aktivierung von Ressourcen im Therapieprozess als wichtiger psychotherapeutischer Wirkfaktor angesehen werden ( Grawe, 2004 ). Aus den gleichen Studien wird ebenfalls ersichtlich, dass die Ressourcenaktivierung in den meisten Therapien nicht optimal genutzt wird. Ziel der vorliegenden, im ambulanten Setting durchgeführten Pilotstudie ist es zu überprüfen, ob dieser Wirkfaktor aktiv gesteigert werden kann. Unmittelbar vor den ersten fünf Therapiestunden lenkten 11 erfahrene sowie 11 unerfahrene Therapeuten ihre Aufmerksamkeit systematisch auf die Ressourcen ihrer Patienten. Durch diese Intervention der gezielten Aufmerksamkeitslenkung hin zu den Ressourcen der Patienten (Ressourcenpriming) konnte die globale Ressourcenaktivierung, operationalisiert durch Stundenbögen und Video-Fremdratings, in den einzelnen Sitzungen erhöht werden. Zudem konnte der Aufbau der Therapiebeziehung nachhaltig verbessert werden. Erfahrenen Therapeuten gelang es, die Problembearbeitung in dieser frühen Therapiephase zu steigern. Durch die unmittelbare Aufmerksamkeitsfokussierung mittels des Ressourcenprimings werden erfolgsrelevante Therapieprozesse (Therapiebeziehung, Problemaktualisierung) bereits zu Therapiebeginn positiv beeinflusst.
The Swedish Version of the Temperament and Character Inventory (TCI)
Authors: Brändström Sven , Sigvardsson Sören , Nylander Per-Olof , Richter Jörg
Published: January 2008

Abstract. In order to establish new norms of the Swedish version of the Temperament and Character Inventory (TCI), data from 2,209 Swedish individuals (age between 13 and 80) was analyzed. The second aim was to evaluate the impact of age and gender on the questionnaire scores. The third aim was to investigate whether the TCI can be meaningfully applied to adolescents in personality assessment as a basis for further research and clinical studies. Age and gender showed independent effects on personality dimensions, which implies that age and gender specific norms have to be established for the TCI. Furthermore, the results in terms of inconsistencies in the correlational and factorial structure, as well as low internal consistency scores in the younger age groups, suggest that the adult version of the TCI should not be applied below the age of 17; for these age groups we recommend the use of the junior TCI (JTCI). The inventory is under further development and several items are in need of revision in order to create less complicated formulations, enabling an improvement in the psychometrics.
Psychometric Properties of the Spanish and American Versions of the ECR Adult Attachment Questionnaire
Authors: Alonso-Arbiol Itziar , Balluerka Nekane , Shaver Phillip R. , Gillath Omri
Published: January 2008

Abstract. We compared the psychometric properties of the American and Spanish versions of the Experiences in Close Relationship measure (ECR; Brennan, Clark, & Shaver, 1998 ; ECR-S, Alonso-Arbiol, Balluerka, & Shaver, 2007 ; Alonso-Arbiol, Shaver, & Yárnoz, 2002) , which assesses individual differences in attachment-related anxiety and avoidance. The American version of the questionnaire was administered to 1,265 Americans and the Spanish version to 747 Spaniards, all of them university students. The results indicate that the two linguistic versions are comparable, and that the Avoidance and Anxiety scales exhibit high internal consistency reliability in both languages, although the α values are slightly lower for the Spanish version. Avoidance was related to relationship status in both language groups, with about the same effect size. The factor structure of the measure was similar across both the American and Spanish samples.
Factorial Invariance and the Specification of Second-Order Latent Growth Models
Authors: Ferrer Emilio , Balluerka Nekane , Widaman Keith F.
Published: January 2008

Abstract. Latent growth modeling has been a topic of intense interest during the past two decades. Most theoretical and applied work has employed first-order growth models, in which a single manifest variable serves as indicator of trait level at each time of measurement. In the current paper, we concentrate on issues regarding second-order growth models, which have multiple indicators at each time of measurement. With multiple indicators, tests of factorial invariance of parameters across times of measurement can be tested. We conduct such tests using two sets of data, which differ in the extent to which factorial invariance holds, and evaluate longitudinal confirmatory factor, latent growth curve, and latent difference score models. We demonstrate that, if factorial invariance fails to hold, choice of indicator used to identify the latent variable can have substantial influences on the characterization of patterns of growth, strong enough to alter conclusions about growth. We also discuss matters related to the scaling of growth factors and conclude with recommendations for practice and for future research.
Asymptotic Distribution Free Interval Estimation
Authors: Coffman Donna L. , Maydeu-Olivares Alberto , Arnau Jaume
Published: January 2008

Abstract. Confidence intervals for the intraclass correlation coefficient (ICC) have been proposed under the assumption of multivariate normality. We propose confidence intervals which do not require distributional assumptions. We performed a simulation study to assess the coverage rates of normal theory (NT) and asymptotically distribution free (ADF) intervals. We found that the ADF intervals performed better than the NT intervals when kurtosis was greater than 4. When violations of distributional assumptions were not too severe, both the intervals performed about the same. The point estimate of the ICC was robust to distributional violations. We provide R code for computing the ADF confidence intervals for the ICC.
Kinematic properties of solar coronal mass ejections: Correction for projection effects in spacecraft coronagraph measurements
Authors: Howard T. A. , Nandy D. , Koepke A. C.
Published: January 2008

One of the main sources of uncertainty in quantifying the kinematic properties of coronal mass ejections (CMEs) using coronagraphs is the fact that coronagraph images are projected into the sky plane, resulting in measurements which can differ significantly from their actual values. By identifying solar surface source regions of CMEs using X‐ray and Hα flare and disappearing filament data, and through considerations of CME trajectories in three‐dimensional (3‐D) geometry, we have devised a methodology to correct for the projection effect. We outline this method here. The methodology was automated and applied to over 10,000 CMEs in the Coordinated Data Analysis Workshop (CDAW) (SOHO Large Angle Spectroscopic Coronagraph) catalog spanning 1996–2005, in which we could associate 1961 CMEs with an appropriate surface event. In the latter subset, deprojected speeds, accelerations, and launch angles were determined to study CME kinematics. Our analysis of this subset of events reconfirms some important trends, notably that previously uncovered solar cycle variation of CME properties are preserved, CMEs with greater width have higher speeds, and slower CMEs tend to accelerate while faster CMEs tend to decelerate. This points out that statistical trends in CME properties, recovered from plane‐of‐sky measurements, may be preserved even in the face of more sophisticated 3‐D measurements from spacecrafts such as STEREO, if CME trajectories are predominantly radial. However, our results also show that the magnitude of corrected measurements can differ significantly from the projected plane‐of‐sky measurements on a case‐by‐case basis and that acceleration is more sensitive to the deprojection process than speed. Average corrected speed and acceleration tend to be a factor of 1.7 and 4.4 higher than their projected values, with mean corrected speed and acceleration magnitudes being on the order of 1000 km/s and 50 m/s2, respectively. We conclude that while using the plane‐of‐sky measurements may be suitable for studies of general trends in a large sample of events, correcting for projection effects is mandatory for those investigations which rely on a numerically precise determination of the properties of individual CMEs.
Jupiter’s changing auroral location
Authors: Grodent Denis , Gérard Jean‐Claude , Radioti Aikaterini , Bonfond Bertrand , Saglam Adem
Published: January 2008

We examine the case of significant latitudinal shifts of the Jovian northern auroral emissions appearing in a data set spanning nine years of observations with the Hubble Space Telescope in the far ultraviolet. The extended data set makes it possible to compare the location of the main auroral emission with similar viewing geometries and satellite positions. The main auroral emission is assumed to originate from beyond the orbit of Ganymede (15 Jovian radii). At these distances, near corotation enforcement and transfer of momentum from Jupiter to the magnetospheric plasma is ensured by means of field aligned currents. The field aligned currents away from Jupiter are carried by downward energetic electrons loosing their energy to the polar atmosphere and giving rise to the main auroral emission. Analysis of the polar projected images shows that the latitudinal location of the main emission has changed by up to 3° over long periods of time. It also shows that the footprint of Ganymede follows a similar trend. We have used the VIP4 magnetic field model to map the emission down to the equatorial plane. This mapping suggests that internal variations of the current sheet parameters might be used as an alternative or complementary explanation to the changing solar wind conditions at Jupiter to explain the observed shift of auroral latitudes.