bluuebunny/crossref_metadata_2025 huggingface dataset:
An improved approximation for calculation of confidence intervals after a sequential clinical trial
Authors: Facey Karen M. , Whitehead John
Published: April 2007

A method for the calculation of confidence intervals following a sequential clinical trial is proposed which is more accurate than methods based solely on continuous monitoring assumptions, but is not as computationally laborious as previous methods suggested for group sequential trials. The calculation takes account of the excess of the sample path over the boundary at the final inspection of the trial, which may be substantial after group sequential monitoring, and is ignored when continuous monitoring is assumed. Accuracy of such confidence intervals after a triangular test is investigated by simulation of coverage probabilities, individual confidence limit probabilities and p‐value curves.
Predictive value of statistical models
Authors: Van Houwelingen J. C. , Le Cessie S.
Published: April 2007

A review is given of different ways of estimating the error rate of a prediction rule based on a statistical model. A distinction is drawn between apparent, optimum and actual error rates. Moreover it is shown how cross‐validation can be used to obtain an adjusted predictor with smaller error rate. A detailed discussion is given for ordinary least squares, logistic regression and Cox regression in survival analysis. Finally, the split‐sample approach is discussed and demonstrated on two data sets.
Principles, problems and a paradox with the measurement of energy expenditure of free‐living subjects using doubly‐labelled water
Authors: Speakman J. R.
Published: April 2007

Many aspects of the study of human nutrition would benefit from the ability to measure the energy which is expended by subjects as they go about their normal activities. The doubly‐labelled water technique is a method which allows such measures to be made. The technique depends on the principle that a measure of carbon dioxide production is possible from the difference in the rates at which isotopic labels of hydrogen and oxygen are eliminated from the body. This simple explanation however conceals a host of assumptions. Several issues have emerged as important in the application of the technique to humans. These issues include first, the use of two samples (an initial and final sample) or multiple samples to estimate the rates of isotope elimination, and secondly the appropriate use of dilution spaces. This paper reviews the current status of the debates concerning these two issues. Paradoxically, improvements in our understanding of the technique, in the methods for calculating carbon dioxide production and in the accuracy of mass spectrometry, have not led to improvements in the accuracy of the technique. The mean deviation of estimates of carbon dioxide production using the technique from estimates made by conventional methods averages 7 per cent.
Adjusting for early treatment termination in comparative clinical trials
Authors: Lagakos S. W. , Lim L. L‐Y. , Robins J. M.
Published: April 2007

In clinical trials of long‐term therapies, patients often terminate their treatments earlier than planned. When analysing time‐to‐failure data, one approach to account for early treatment termination censors failure at the time of termination of therapy. In general, however, this does not produce valid inferences about the distribution of time to failure that would have occurred had treatment not been terminated. In contrast, intent‐to‐treat analyses, which are based on time to failure regardless of whether and when treatment is terminated, always produce valid inferences about the unconditional distribution of time to failure. Early treatment termination does not distort the size (type I error rate) of intent‐to‐treat tests but can cause a loss in power. Modifications to ordinary logrank tests can be used to recover some of the lost power without affecting test size, and can be most useful when the proportion of at‐risk patients still taking their treatment changes substantially during periods when failures are observed. Extensions of the modified test to include strata are straightforward, although important design questions require further research.
Testing for imbalance of covariates in controlled experiments
Authors: Permutt Thomas
Published: April 2007

Results of a controlled experiment are often adjusted for covariates found by a preliminary test to differ significantly between the treatment and control groups. The resulting test's true significance level is lower than the nominal level. Greater power can be achieved by always adjusting for a covariate that is highly correlated with the response regardless of its distribution between groups.
Optimum allocation of samples in strata‐matching case‐control studies when cost per sample differs from stratum to stratum
Authors: Nam Jun‐Mo , Fears Thomas R.
Published: April 2007

We investigate the allocation of samples over strata in case‐control studies with consideration of sampling costs. We consider two situations, typical of strata‐matched case‐control studies. Subject to a fixed total cost we derive optimum allocations that maximize the asymptotic efficiency of Cochran's test, that is, minimize the variance of the maximum likelihood estimator of the common odds ratio when the common odds ratio is one. Our results show that the standard design with equal numbers of cases and controls in each stratum is inefficient when costs per control differ greatly from stratum to stratum. We show that the optimum design suggested in this paper is robust for values of the odds ratio common in epidemiologic studies.
Sample size determination for case‐control studies: The influence of the joint distribution of exposure and confounder
Authors: Lui Kung‐Jong
Published: April 2007

In case‐control studies, the results about how the exposure distribution affects sample size are well known. This paper extends previous results by incorporating the effect of a confounder into the calculation of sample size for a desired size and power of a statistical test. The paper also includes a quantitative discussion on the influence of the joint distribution for exposure to a putative cause and a confounder on required sample sizes. The results show that, to detect a specified alternative for a given size and power, the required sample size decreases as either the variance of exposure or the effect of exposure on disease increases. The required sample size, however, increases as either the variance of the confounder or the effect of the confounder on disease increases. Generally, the higher is the absolute value of the simple correlation between the exposure and the confounder, the larger is the required sample size.
Relation of pooled logistic regression to time dependent cox regression analysis: The framingham heart study
Authors: D'Agostino Ralph B. , Lee Mei‐Ling , Belanger Albert J. , Cupples L. Adrienne , Anderson Keaven , Kannel William B.
Published: April 2007

A standard analysis of the Framingham Heart Study data is a generalized person‐years approach in which risk factors or covariates are measured every two years with a follow‐up between these measurement times to observe the occurrence of events such as cardiovascular disease. Observations over multiple intervals are pooled into a single sample and a logistic regression is employed to relate the risk factors to the occurrence of the event. We show that this pooled logistic regression is close to the time dependent covariate Cox regression analysis. Numerical examples covering a variety of sample sizes and proportions of events display the closeness of this relationship in situations typical of the Framingham Study. A proof of the relationship and the necessary conditions are given in the Appendix.
Maximum likelihood regression methods for paired binary data
Authors: Lipsitz Stuart R. , Laird Nan M. , Harrington David P.
Published: April 2007

We discuss maximum likelihood methods for analysing binary responses measured at two times, such as in a cross‐over design. We construct a 2 × 2 table for each individual with cell probabilities corresponding to the cross‐classification of the responses at the two times; the underlying likelihood for each individual is multinomial with four cells. The three dimensional parameter space of the multinomial distribution is completely specified by the two marginal probabilities of success of the 2 × 2 table and an association parameter between the binary responses at the two times. We examine a logistic model for the marginal probabilities of the 2 × 2 table for individual i; the association parameters we consider are either the correlation coefficient, the odds ratio or the relative risk. Simulations show that the parameter estimates for the logistic regression model for the marginal probabilities are not very sensitive to the parameters used to describe the association between the binary responses at the two times. Thus, we suggest choosing the measure of association for ease of interpretation.
Reactive power capability of a wind turbine with doubly fed induction generator
Authors: Lund Torsten , Sørensen Poul , Eek Jarle
Published: April 2007

The aim of the work is to derive a steady state PQ‐diagram for a variable speed wind turbine equipped with a Doubly Fed Induction Generator. Firstly, the dependency between optimal rotor speed and wind speed is presented. Secondly, the limitations in reactive power production, caused by the rotor current, the rotor voltage and the stator current are derived. Thirdly, the influence of switching from Δ to Y coupling of the stator is investigated. Finally, a complete PQ diagram for a wind turbine is plotted. It is concluded that the limiting factor regarding reactive power production will typically be the rotor current limit, and that the limit for reactive power absorption will be the stator current limit. Further, it is concluded that the rotor voltage will only have a limiting effect at high positive and negative slips, but near the limitation, the reactive power capability is very sensitive to small changes in the slip. Copyright © 2007 John Wiley & Sons, Ltd.
Functional analysis of genes involved in the biosynthesis of isoprene in Bacillus subtilis
Authors: Julsing Mattijs K. , Rijpkema Michael , Woerdenbag Herman J. , Quax Wim J. , Kayser Oliver
Published: April 2007

In comparison to other bacteria Bacillus subtilis emits the volatile compound isoprene in high concentrations. Isoprene is the smallest representative of the natural product group of terpenoids. A search in the genome of B. subtilis resulted in a set of genes with yet unknown function, but putatively involved in the methylerythritol phosphate (MEP) pathway to isoprene. Further identification of these genes would give the possibility to engineer B. subtilis as a host cell for the production of terpenoids like the valuable plant-produced drugs artemisinin and paclitaxel. Conditional knock-out strains of putative genes were analyzed for the amount of isoprene emitted. Differences in isoprene emission were used to identify the function of the enzymes and of the corresponding selected genes in the MEP pathway. We give proof on a biochemical level that several of these selected genes from this species are involved in isoprene biosynthesis. This opens the possibilities to investigate the physiological function of isoprene emission and to increase the endogenous flux to the terpenoid precursors, isopentenyl diphosphate and dimethylallyl diphosphate, for the heterologous production of more complex terpenoids in B. subtilis.
Effect of Parathyroidectomy on Quality of Life and Neuropsychological Symptoms in Primary Hyperparathyroidism
Authors: Weber Theresia , Keller Monika , Hense Isabella , Pietsch Alexander , Hinz Ulf , Schilling Tobias , Nawroth Peter , Klar Ernst , Büchler Markus W.
Published: April 2007

Neuropsychological symptoms are found in a certain number of patients with primary hyperparathyroidism (PHPT). Preoperative and postoperative quality of life, anxiety, and depression are measured to analyze the impact of parathyroidectomy on these symptoms. In this prospective study, 66 patients underwent parathyroidectomy for PHPT and were evaluated pre‐ and postoperatively with two validated psychometric instruments (HADS, PHQ‐9). Health‐related quality of life was measured with a 12‐item short‐form health survey (SF‐12). Preoperatively, the median physical component score (SF‐12) of 43.0 and mental component score of 43.5 were lower than those of the general population (52.8 and 54.2 points, respectively). One year postoperatively the mental component score increased to 48.6 (p = 0.011), whereas the physical functioning scale scored 45.3 and therefore did not change significantly (p = 0.585). Preoperatively, symptoms of depression were found in 23.4% of the patients, and 15.6% of the patients displayed symptoms of anxiety (HADS). The prevalence of depression was significantly higher in patients with preoperative serum calcium levels > 11.2 mg/dl (2.8 mmol/L) (p = 0.015). Twelve months postoperatively, the overall proportion of patients with anxiety and depression decreased to 7.8% and 15.7%, respectively (p = NS). The severity of depression as measured with the PHQ‐9 declined postoperatively as well. In this study, preoperative neuropsychological symptoms were related to the serum calcium levels. Postoperative health‐related quality of life improved significantly. Among patients with preoperative symptoms of depression and anxiety, both symptoms were alleviated significantly at the 12‐month follow‐up. Therefore, surgery for PHPT seems to be effective in reducing neuropsychological morbidity associated with PHPT.
Intermediate hyperhomocysteinaemia and compound heterozygosity for the common variant c.677C>T and a MTHFR gene mutation
Authors: Rummel T. , Suormala T. , Häberle J. , Koch H. G. , Berning C. , Perrett D. , Fowler B.
Published: April 2007

Methylenetetrahydrofolate reductase (MTHFR) is a key enzyme in the regulation of plasma homocysteine levels. MTHFR deficiency, an autosomal recessive disorder, results in homocystinuria and hypomethioninaemia and presents with highly variable symptoms affecting many organs but predominantly the central nervous system. The common polymorphism of the MTHFR gene, c.677C>T, a known risk factor for elevated plasma homocysteine levels, occurs frequently in the caucasian population. In this study we investigated three subjects with moderate hyperhomocysteinaemia (total plasma homocysteine 72 μmol/L in case 1 and 90 μmol/L in case 3, total non‐protein‐bound homocysteine 144–186 μmol/L in case 2) but different clinical presentation with no symptoms in case 1, muscle weakness at 17 years of age in case 2, and syncopes and cerebral convulsions at 18 years of age in case 3. Each subject was compound heterozygous for the c.677C>T polymorphism and a novel mutation of the MTHFR gene (case 1: c.883G>A [p.D291N]; case 2: c.1552_c.1553delGA [p.E514fsX536]; case 3: c.616C>T [p.P202S]). Moderately decreased fibroblast MTHFR activity was associated with severely reduced affinity for NADPH and increased sensitivity to inhibition by S‐adenosylmethionine (AdoMet) in case 2, and with mild FAD responsiveness in case 3. In case 1, fibroblast MTHFR activity was normal but the sensitivity to inhibition by AdoMet was slightly reduced. This study indicates that the sequence alteration c.677C>T combined with severe MTHFR mutations in compound heterozygous state may lead to moderate biochemical and clinical abnormalities exceeding those attributed to the c.677TT genotype and might require in addition to folate substitution further therapy to normalize homocysteine levels.
High incidence of autoantibodies in Fabry disease patients
Authors: Martinez P. , Aggio M. , Rozenfeld P.
Published: April 2007

Fabry disease (FD) is an X‐linked disorder of glycosphingolipid catabolism that results from a deficiency of the lysosomal enzyme α‐galactosidase A. This defect leads to the accumulation of its substrates, mainly globotriaosylceramide, in lysosomes of cells of different tissues. Different studies have shown the involvement of immunopathologies in different sphingolipidoses. The coexistence of FD and immune disorders such as systemic lupus erythematosus, rheumatoid arthritis and IgA nephropathy, has been described in the literature. The aim of this study was to evaluate the prevalence of a group of autoantibodies in a series of Argentine FD patients. Autoantibodies against extractable nuclear antigens (ENAs), double‐stranded DNA, anticardiolipin and phosphatidylserine were assayed by ELISA. Lupus anticoagulants were also tested. Fifty‐seven per cent of the samples showed reactivity with at least one autoantigen. Such reactivities were more frequent among males than among females. Antiphospholipid autoantibodies were detected in 45% of our patients. The high rate of thrombosis associated with FD could be related, at least in part, to the presence of antiphospholipid autoantibodies in Fabry patients. We found the presence of ENAs, which are a characteristic finding of rheumatological diseases, previous a frequent misdiagnosis of FD, in around 39% of the cases. The detection of a high level of autoantibodies must be correlated clinically to determine the existence of an underlying autoimmune disease. With the recent development of therapy, the life expectancy in FD will increase and autoimmune diseases might play an important role in the morbidity of FD.
Bovine mucopolysaccharidosis type IIIB
Authors: Karageorgos L. , Hill B. , Bawden M. J. , Hopwood J. J.
Published: April 2007

Mucopolysaccharidosis IIIB, an autosomal recessive lysosomal storage disorder of heparan sulfate caused by mutations in the α‐N‐acetylglucosaminidase (NAGLU) gene, was recently discovered in cattle. Clinical signs include progressive ataxia, stumbling gait, swaying and difficulty in balance and walking. These clinical signs are usually first observed at approximately 2 years of age and then develop progressively over the lifespan of the animals. Affected bulls were found to be homozygous for the missense mutation E452K (c.1354G> A). The availability of mutational analysis permits screening for the NAGLU mutation to eradicate this mutation from the cattle breeding population.
Neuregulin 1 is a pronociceptive cytokine that is regulated by progesterone in the spinal cord: Implications for sex specific pain modulation
Authors: LaCroix‐Fralish Michael L. , Tawfik Vivianne L. , Nutile‐McMenemy Nancy , DeLeo Joyce A.
Published: April 2007

Sex differences in the magnitude of response to thermal and tactile stimuli have been demonstrated in both clinical and animal studies. Females typically display lower threshold responses to painful stimuli as compared to males. We have previously observed sexually dimorphic expression of the growth factor, neuregulin 1 (NRG1) following L5 nerve root ligation (LR) in male and female rats. In the present study, we sought to determine which gonadal hormones were involved in regulating NRG1 expression following L5 nerve root ligation. We observed that expression of NRG1 mRNA and the neuregulin receptors, ErbB2 and ErbB4 in the lumbar spinal cord was facilitated by the presence of progesterone in female rats following L5 nerve root ligation. An increase in NRG1 protein and NRG1 immunoreactivity was also observed in the ipsilateral spinal cord of progesterone treated female rats as compared to ovariectomized female rats and male rats at day 14 following LR. NRG1 immunoreactivity was equally colocalized with either the astrocytic marker, GFAP, and with NeuN labeled neurons 14days following L5 nerve root ligation. Intrathecal administration of recombinant NRG1‐β1 protein significantly decreased the hindpaw tactile withdrawal threshold in male rats, ovariectomized female rats, and progesterone treated female rats. These results demonstrate a role for progesterone‐dependent regulation of glial and/or neuronal neuregulin 1 in female rats in mediating sex differences in nociception. Furthermore, our results suggest that NRG1 may be involved in central sensitization during the maintenance phase, but not in the initiation of persistent pain in female rats.
Chromosomal size conservation through the cell cycle supports karyotype stability in Trypanosoma cruzi
Authors: Galindo Mario , Sabaj Valeria , Espinoza Ingrid , Toro Gabriela Cecilia , Búa Jaqueline , Grenet Jose , López-Solís Remigio , Ruiz Andres Mariano , Galanti Norbel
Published: April 2007

The Trypanosoma cruzi karyotype shows an extensive chromosomal size polymorphism. Absence of condensed mitotic chromosomes and chromatin fragility are characteristic features of T. cruzi which would allow DNA breaks and chromosomal rearrangements during cell proliferation. We have investigated by pulsed field gel electrophoresis (PFGE) eventual changes in chromosomal size during exponential and stationary phases of T. cruzi epimastigotes in culture, in G0 trypomastigotes and throughout the cell cycle in synchronized epimastigotes. T. cruzi molecular karyotype was stable throughout the cell cycle and during differentiation. Thus, the chromosomal size polymorphism previously reported in T. cruzi contrasts with the stability of the molecular karyotype observed here and suggests that chromosomal rearrangements leading to changes in chromosomal size are scarce events during the clonal propagation of this parasite.
Stress on redox
Authors: Bánhegyi Gábor , Benedetti Angelo , Csala Miklós , Mandl József
Published: April 2007

Redox imbalance in the endoplasmic reticulum lumen is the most frequent cause of endoplasmic reticulum stress and consequent apoptosis. The mechanism involves the impairment of oxidative protein folding, the accumulation of unfolded/misfolded proteins in the lumen and the initiation of the unfolded protein response. The participation of several redox systems (glutathione, ascorbate, FAD, tocopherol, vitamin K) has been demonstrated in the process. Recent findings have attracted attention to the possible mechanistic role of luminal pyridine nucleotides in the endoplasmic reticulum stress. The aim of this minireview is to summarize the luminal redox systems and the redox sensing mechanisms of the endoplasmic reticulum.
Chaperonopathies and chaperonotherapy
Authors: Macario Alberto J.L. , Conway de Macario Everly
Published: April 2007

The study of molecular chaperones (genetics, structure, location, physiology, pathology, and therapeutics) has developed into a science with specific objectives, methods, and hypotheses, a discipline we called chaperonology. Subdisciplines of chaperonology include the study of pathological chaperones (chaperonopathies) and the analysis of their genes in sequenced genomes (chaperonomics). Chaperonopathies are pathological conditions in which one type of chaperone is deficient due to a genetic or acquired defect that modifies the chaperone's structure and/or makes the chaperone unavailable for functioning when needed. Experimental and clinical data show that chaperones and their genes can be used for treating various pathological conditions, thus justifying the development of chaperonotherapy. We discuss recent work showing that chaperonotherapy is on solid foundations: the data demonstrate that molecular chaperones counteract pathogenetic mechanisms in disease and during stress.
Polyamines prevent NaCl‐induced K+ efflux from pea mesophyll by blocking non‐selective cation channels
Authors: Shabala Sergey , Cuin Tracey A. , Pottosin Igor
Published: April 2007

Despite numerous reports implicating polyamines in plant salinity responses, the specific ionic mechanisms of polyamine‐mediated adaptation to salt‐stress remain elusive. In this work, we show that micromolar concentrations of polyamines are efficient in preventing NaCl‐induced K+ efflux from the leaf mesophyll, and that this effect can be attributed to the inhibition of non‐selective cation channels in mesophyll. The inhibition by externally applied polyamines developed slowly over time, suggesting a cytosolic mode of action. Overall, we suggest that elevated levels of cellular polyamine may modulate the activity of plasma membrane ion channels, improving ionic relations and assisting in a plant's adaptation to salinity.
Hsp27 (HspB1) and αB‐crystallin (HspB5) as therapeutic targets
Authors: Arrigo André-Patrick , Simon Stéphanie , Gibert Benjamin , Kretz-Remy Carole , Nivon Mathieu , Czekalla Anna , Guillet Dominique , Moulin Maryline , Diaz-Latoud Chantal , Vicart Patrick
Published: April 2007

Hsp27 and αB‐crystallin are molecular chaperones that are constitutively expressed in several mammalian cells, particularly in pathological conditions. These proteins share functions as diverse as protection against toxicity mediated by aberrantly folded proteins or oxidative‐inflammation conditions. In addition, these proteins share anti‐apoptotic properties and are tumorigenic when expressed in cancer cells. This review summarizes the current knowledge about Hsp27 and αB‐crystallin and the implications, either positive or deleterious, of these proteins in pathologies such as neurodegenerative diseases, myopathies, asthma, cataracts and cancers. Approaches towards therapeutic strategies aimed at modulating the expression and/or the activities of Hsp27 and αB‐crystallin are presented.
Differential effects of tannic acid on cisplatin induced nephrotoxicity in rats
Authors: Tikoo Kulbhushan , Bhatt Deepak Kumar , Gaikwad Anil Bhanudas , Sharma Vikram , Kabra Dhiraj G.
Published: April 2007

Cisplatin is a widely used antineoplastic drug. Major drawback of cisplatin therapy is its nephrotoxicity. The objective of this study was to check the effect of tannic acid on cisplatin induced nephrotoxicity. Post‐treatment of tannic acid prevents cisplatin (5 mg/kg) induced nephrotoxicity and decreases poly(ADP‐ribose) polymerase cleavage, phosphorylation of p38 and hypoacetylation of histone H4. In contrast, co‐treatment of tannic acid potentiates the nephrotoxicity. Comparative nephrotoxicity studies show that co‐treatment of tannic acid with reduced dose of cisplatin (1.5 mg/kg) developed almost similar nephrotoxicity. MALDI protein profiling of plasma samples provides indirect evidence that tannic acid co‐treatment increases bioavailability of cisplatin.
Provenance comparisons of Permian to Jurassic tectonostratigraphic terranes in New Zealand: perspectives from detrital zircon age patterns
Authors: ADAMS C. J. , CAMPBELL H. J. , GRIFFIN W. L.
Published: April 2007

U–Pb detrital zircon ages (LAM-ICPMS) are reported for 20 greywackes and sandstones from seven major tectono-stratigraphic terranes of the Eastern Province of New Zealand (Cretaceous to Carboniferous) to constrain sediment provenances. Samples are mainly from three time horizons: Late Permian, Late Triassic and Late Jurassic. Age datasets are analysed as percentages in geological intervals, and in histogram and cumulative probability diagrams. The latter discriminate significant zircon age components in terms of terrane, sample stratigraphic age, component age, precision and percentage (of total set). Zircon age distributions from all samples have persistent, large Triassic–Permian, and very few Devonian–Silurian, populations, features which exclude a sediment provenance from the early Palaeozoic, Lachlan Fold Belt of southeast Australia or continuations in New Zealand and Antarctica. In the accretionary terranes, significant Palaeozoic (and Precambrian) zircon age populations are present in Torlesse and Waipapa terranes, and variably in Caples terrane. In the fore-arc and back-arc terranes, a unimodal character persists in Murihiku and Brook Street terranes, while Dun Mountain–Maitai terrane is more variable, and with Caples terrane, displays a hybrid character. Required extensive Triassic–Permian zircon sources can only be found within the New England Fold Belt and Hodgkinson Province of northeast Australia, and southward continuations to Dampier Ridge, Lord Howe Rise and West Norfolk Ridge (Tasman Sea). Small but significant Palaeozoic (and Precambrian) age components in the accretionary terranes (plus Dun Mountain–Maitai terrane), have sources in hinterlands of the New England Fold Belt, in particular to mid-Palaeozoic granite complexes in NE Queensland, and Carboniferous granite complexes in NE New South Wales. Major and minor components place sources (1) for the older Torlesse (Rakaia) terrane, in NE Queensland, and (2) for Waipapa terrane, in NE New South Wales, with Dun Mountain–Maitai and Caples terrane sources more inshore and offshore, respectively. In Early Jurassic–Late Cretaceous, Torlesse (Pahau) and Waipapa terranes, there is less continental influence, and more isolated, offshore volcanic arc sources are suggested. There is local input of plutonic rock detritus into Pahau depocentres from the Median Batholith in New Zealand, or its northward continuation on Lord Howe Rise. Excepting Murihiku and Brook Street terranes, all others are suspect terranes, with depocentres close to the contemporary Gondwanaland margin in NE Australia, and subsequent margin-parallel, tectonic transport to their present New Zealand position. This is highlighted by a slight southeastward migration of terrane depocentres with time. Murihiku and Brook Street terrane sources are more remote from continental influences and represent isolated offshore volcanic depocentres, perhaps in their present New Zealand position.
The Decline and Fall of the Jobber System in the Bombay Cotton Textile Industry, 1870–1955
Authors: CHANDAVARKAR RAJNARAYAN
Published: April 2007

In 1981, on the eve of the general strike that convulsed the Bombay cotton textile industry, millowners, managers and workers alike acknowledged that the jobber was a thing of the past. The jobber system, they agreed, had been dismantled decades previously.
Das maligne fibröse Histiozytom der Mamma: Klinische Bedeutung einer seltenen Diagnose
Authors: Kunz  , Friedrich
Published: April 2007

Bei weniger als 1% der primären Malignome der Brust handelt es sich um Sarkome. Unter diesen sind maligne fibröse Histiozytome (MFH) selten. Prospektive randomisierte Untersuchungen sind der Seltenheit wegen nicht möglich. Nach organerhaltender Therapie von Mammakarzinomen und Nachbestrahlung haben Fallberichte über Sarkome der Mamma zugenommen. Auch wenn MFH der Brust sehr selten sind, ist voraussichtlich durch zunehmende Verbreitung der organerhaltenden Therapie des Mammakarzinoms mit einem Inzidenzanstieg zu rechnen, sodass Bemühungen einer Therapieoptimierung gerechtfertigt sind. MFH sollten bei grossem Tumordurchmesser, rasch progredientem Tumorwachstum und Fehlen von axillären Lymphknoten- oder Fernmetastasen in die Differentialdiagnose von Brusttumoren einbezogen werden. Berichtet wird über eine 90-jährige Patientin mit exulzeriertem MFH der linken Mamma. Eine vorausgegangene Strahlentherapie ist bei ihr nicht bekannt.
Subtherapeutische Phenytoinspiegel infolge eines Medikationsfehlers
Authors: Burri  , Rüegg  , Rutishauser  , Egger  , Lampert
Published: April 2007

Der Fall beschreibt eine Patientin, die mit dem klinischen Bild eines temporoparietookzipitalen Syndroms notfallmässig zugewiesen und in der Annahme einer zerebralen Ischämie lysiert wurde. Im Anschluss an die Lysetherapie manifestierten sich rezidivierende partiell-einfache motorische epileptische Anfälle, und es wurde eine antiepileptische Therapie mit Phenytoin i.v. begonnen. Im Verlauf kam es zu einem pharmakokinetisch nicht erklärbaren Abfall der Phenytoin-Spiegel im Serum auf subtherapeutische Werte. Erst die genaue Überprüfung der Medikamentenapplikation ergab, dass die Phenytoin-Injektionslösung fälschlicherweise nicht direkt intravenös, sondern als Kurzinfusion verabreicht worden war. Die infolge Verdünnung auskristallisierte Substanz blieb so im Partikelfilter des Infusionsbesteckes zurück, und die Patientin erhielt eine zu tiefe, nicht kalkulierbare Dosis.
Das Generieren von Bildern als Verstehenshilfe beim Lernen aus Texten
Authors: Seufert Tina , Zander Steffi , Brünken Roland
Published: April 2007

Zusammenfassung. Das Generieren von Bildern erfordert vom Lernenden das Erkennen globaler Strukturen eines Sachverhalts und unterstützt somit Verstehensprozesse. In zwei experimentellen Studien wurde untersucht, ob erwachsene Lernende von der Strategie, Bilder als Verstehenshilfe einzusetzen, tatsächlich Gebrauch machen und ob diese Strategie durch Instruktion gefördert werden kann oder muss. Lernende sollten vorliegende Texte entweder in beliebiger (neutrale Instruktion) oder in bildhafter Form (Bildinstruktion) festhalten, um später anhand dieser Repräsentationen Behaltens- und Verstehensfragen zu beantworten. Im ersten Experiment (n = 17) zeigte sich, dass Lernende durch Instruktion signifikant mehr Bilder erstellen und auch ihre Lernleistung steigt. In Experiment 2 (n = 38) konnte gezeigt werden, dass sich zwar die Anzahl der Bilder durch die Instruktion verbessert, nicht jedoch deren Güte. Zudem konnten die Ergebnisse bezüglich der räumlichen Fähigkeiten der Lernenden differenziert werden: Lernende mit geringeren räumlichen Fähigkeiten zeigen ein Mediationsdefizit, da sich auch durch die Instruktion keine Verbesserung des funktionalen Bildeinsatzes zeigt, während Lernende mit höheren räumlichen Fähigkeiten unabhängig von der Instruktion guten Strategieeinsatz mit guten Leistungswerten zeigen, ihre Fähigkeiten also kompensierend wirken.
Das Hinweisreizparadigma - sportpsychologische Anwendungen im Überblick
Authors: Cañal-Bruland Rouwen
Published: April 2007

Zusammenfassung. Das Hinweisreizparadigma ist in der Psychologie seit Ende der 70er-Jahre vielfach genutzt worden, um selektive visuelle Aufmerksamkeit hinsichtlich verschiedener Aspekte zu untersuchen. Seit Ende der 80er-Jahre wird dieses Paradigma auch aus sportpsychologischer Perspektive angewandt, um z. B. Athleten und Nicht-Athleten oder Sportler unterschiedlicher Sportarten hinsichtlich der Effizienz der Aufmerksamkeitsallokation auf unterschiedliche Reize zu vergleichen. Bisher haben jedoch nur wenige sportpsychologische Studien, die in deutsch- und englischsprachigen Zeitschriften veröffentlicht wurden, das Hinweisreizparadigma genutzt. In diesem Überblicksbeitrag werden diese Studien einerseits sowohl methodisch als auch bez. ihrer Ergebnisse resümiert. Andererseits wird diskutiert, weshalb das Hinweisreizparadigma im Vergleich zum Eye-tracking Paradigma vernachlässigt wurde. Zukünftige Anwendungspotenziale des Hinweisreizparadigmas für die sportpsychologische Forschung werden abschließend skizziert.
Korrelate der Sturzangst im Alter
Authors: Schott Nadja
Published: April 2007

Zusammenfassung. Mit der vorliegenden Untersuchung wurde der Zusammenhang von Sturzangst (Survey of Activities and Fear of Falling in the Elderly: SAFE), funktionalem Gleichgewicht/Mobilität (Timed-Up-and-Go-Test, TUG; Gehgeschwindigkeit) und körperlicher Funktionsfähigkeit (SAFE Aktivitäten, Reduktionen; SF-36) bei älteren Erwachsenen untersucht. Darüber hinaus sollte die Mediatorfunktion sturzassoziierter Selbstwirksamkeit (Activities-Specific Balance Confidence (ABC) Scale) in einem Strukturgleichungsmodell an 91 Erwachsenen (17 Männer, 74 Frauen) im Alter von 60 bis 93 Jahren ohne Sturzhistorie geprüft werden. Man findet signifikant negative Pfade von der Subskala SAFE Angst auf die sturzassoziierte Selbstwirksamkeit (β = -0.931; t = -8.117, p.001), d. h. dass ältere Menschen ohne aktuelle Sturzbiographie und nur geringer Sturzangst eine hohe sturzassoziierte Selbstwirksamkeit berichten. Ebenso ist der Effekt von Sturzangst auf die körperliche Funktionsfähigkeit hochsignifikant (β = -0.432, t = -2.686, p = .007). Für die sturzassoziierte Selbstwirksamkeit liegt ein hoher Zusammenhang mit dem funktionalen Gleichgewicht/Mobilität vor (β = 0.482, t = 2.050, p = .040), jedoch nicht mit der körperlichen Funktionsfähigkeit (β = 0.118, t = 0.916, p = .359). Für den Zusammenhang zwischen Sturzangst und funktionalem Gleichgewicht/Mobilität liegt eine vollständige Mediation durch die sturzassoziierte Selbstwirksamkeit vor. Der signifikante Einfluss von funktionalen Messungen und Verhaltensdaten auf die Sturzangst verdeutlicht die Notwendigkeit von Interventionen, die auf die Stärkung der sturzassoziierten Selbstwirksamkeit fokussieren, um so zur Reduktion von Sturzangst beizutragen.
Role of atmospheric circulation with respect to the interannual variability in the date of snow cover disappearance over northern latitudes between 1988 and 2003
Authors: Vicente‐Serrano Sergio M. , Grippa Manuela , Le Toan Thuy , Mognard Nelly
Published: April 2007

This paper analyzes the main spatial patterns in the dates of snow cover disappearance variability over northern latitudes between 1988 and 2003. The dates of snow cover disappearance were calculated using satellite passive microwave data from the Special Sensor Microwave/Imager. Spatial and temporal patterns were obtained using principal components analysis in the S mode. We identified eight components, each representing a large region characterized by homogeneous interannual variability in the dates of snow cover disappearance. We found that atmospheric circulation, summarized by means of teleconnection indices, had an important impact on the date of snow cover disappearance for most of these regions. A role is played by the Arctic Oscillation in western Siberia, the spring east Atlantic/west Russian pattern in central Siberia, and the Pacific North American pattern in southern Canada, while the El Niño–Southern Oscillation phenomenon and the west Pacific pattern are significantly related to variability in the date of snow cover disappearance in the northernmost areas of America. For the regions where we found no relationship between the interannual variability in the date of snow cover disappearance and the teleconnection indices, a direct relationship with some spatial patterns of sea level pressures, which are not well summarized by the teleconnection indices, was found.
Relationship between the potential and actual intensities of tropical cyclones on interannual time scales
Authors: Wing A. A. , Sobel A. H. , Camargo S. J.
Published: April 2007

The thermodynamic theory for the physics of a mature tropical cyclone (TC) tells us that the cyclone's intensity cannot exceed an upper bound, the potential intensity (PI). This combined with an empirical result due to Emanuel leads to a prediction of average TC intensity change, given the change in PI. The slope of the predicted relationship between percentagewise variations in PI and those in intensity can vary between 0.5 and 1, depending on the mean PI and on what threshold is applied to the intensity data. For the Atlantic and Pacific, typical values are around 0.65 when tropical storms are excluded and 0.8 when they are included. The authors use best track data for the North Atlantic and western North Pacific, combined with PI computed from reanalysis data sets, to test these predictions. The results show that observed interannual variations of maximum TC intensity are consistent with the predictions of PI theory. Modest fractions of the variance in actual intensity are explained by PI variations. Much of the interannual variation in PI experienced by the storms comes from variation in TC tracks, so that the storms in different years are more or less likely to sample regions of high PI, rather than from variations in PI at a fixed location.
Wind‐driven interdecadal variability in the eastern tropical and South Pacific
Authors: Montecinos Aldo , Leth Ole , Pizarro Oscar
Published: April 2007

Simulated interface elevation anomalies with a reduced gravity model forced by observed wind stress are used to investigate the origin of thermocline depth fluctuations in the eastern tropical and South Pacific at interdecadal timescales. It is found that interdecadal thermocline depth fluctuations in the eastern equatorial Pacific and along the western coast of the Americas are fundamentally driven by zonal wind fluctuations in the western equatorial Pacific. Thus positive (negative) interface elevation anomalies, which correspond to shallower (deeper) thermocline depths, in the eastern tropical Pacific and along the west coast of Central and South America are related to easterly (westerly) anomalies in the western sector of the equatorial Pacific. However, off‐equatorial wind fluctuations maintain and reinforce the interdecadal variability observed along the eastern equatorial Pacific and along the west coast of South America. In the latter region, equatorial (off‐equatorial) wind forcing is relatively more important equatorward (poleward) of 30°S. In the eastern equatorial Pacific, interface elevation anomalies are negatively correlated with sea surface temperature (SST) at interdecadal timescales. According to our results the SST interdecadal anomalies are in part (50–60%) driven by wind fluctuations likely through the modulation of vertical advection of cold waters which depends primarily on the thermocline depth forced remotely or locally by winds. This relationship was especially strong during the 1970s and 1980s, a period characterized by the larger zonal wind stress interdecadal fluctuations observed in the western equatorial Pacific.
On the dynamics of Atlantic Water circulation in the Arctic Ocean
Authors: Karcher M. , Kauker F. , Gerdes R. , Hunke E. , Zhang J.
Published: April 2007

We use a subset of models from the coordinated experiment of the Arctic Ocean Model Intercomparison Project (AOMIP) to analyze differences in intensity and sense of rotation of Atlantic Water circulation. We focus on the interpretation of the potential vorticity (PV) balance. Results differ drastically for the Eurasian and the Amerasian Basins of the Arctic Ocean. We find indications that in the Eurasian Basin the lateral net flux of PV is a significant factor for the determination of the sense of rotation of Atlantic Water circulation on timescales beyond pentades. The main source of high PV causing cyclonic circulation in the Eurasian Basin is the Barents Sea, where the seasonal cycle of surface buoyancy fluxes forms stratified water that leaves the shelf and feeds the Atlantic Water Layer (AWL) in the Arctic Basins. However, in the Amerasian Basin vertical PV fluxes are the more important factor. These are closely related to wind field changes. We find an intense response of the AWL flow to wind forcing, approximated by the sea level pressure difference between the Bering Sea and the central Canadian Basin, which describes about half the variance of AWL flow of the Amerasian Basin. An experiment driven with a repeated atmospheric climatology exhibits an extreme case where a permanent high pressure system over the Beaufort Sea dominates the circulation in the Amerasian Basin, demonstrating the potential of the Beaufort Gyre to adjust in such a way as to suppress a cyclonic AWL flow in the Amerasian Basin. In more realistic cases the Beaufort Gyre still modulates the Amerasian Basin AWL circulation significantly.
Alkyl nitrates in outflow from North America over the North Atlantic during Intercontinental Transport of Ozone and Precursors 2004
Authors: Reeves Claire E. , Slemr Jana , Oram David E. , Worton David , Penkett Stuart A. , Stewart David J. , Purvis Ruth , Watson Nicola , Hopkins Jim , Lewis Ally , Methven John , Blake Donald R. , Atlas Elliot
Published: April 2007

This paper is based on alkyl nitrate measurements made over the North Atlantic as part of the International Consortium for Research on Atmospheric Transport and Transformation (ICARTT). The focus is on the analysis of air samples collected on the UK BAe‐146 aircraft during the Intercontinental Transport of Ozone and Precursors (ITOP) project, but air samples collected on board the NASA DC‐8 and NOAA WP‐3D aircraft as part of a Lagrangian experiment are also used. The ratios between the alkyl nitrates and their parent hydrocarbons are compared with those expected from chemical theory. Further, a box model is run to investigate the temporal evolution of the alkyl nitrates in three Lagrangian case studies and compared to observations. The air samples collected during ITOP do not appear to be strongly influenced by oceanic sources, but rather are influenced by emissions from the N.E. United States and from Alaskan fires. There also appears to be a widespread common source of ethyl nitrate and 1‐propyl nitrate other than from their parent hydrocarbons. The general agreement between the alkyl nitrate data and photochemical theory suggests that during the first few days of transport from the source region, photochemical production of alkyl nitrates, and thus ozone, had taken place. The observations in the more photochemically processed air masses are consistent with the alkyl nitrate production reactions no longer dominating the peroxy radical self/cross reactions. Further, the results also suggest that the rates of photochemical processing in the Alaskan smoke plumes were small.
Aerosol acidity in rural New England: Temporal trends and source region analysis
Authors: Ziemba L. D. , Fischer E. , Griffin R. J. , Talbot R. W.
Published: April 2007

Data from 24‐hour bulk filter samples collected by the AIRMAP program were used to estimate aerosol acidity at a site in New England. The sampling site, Thompson Farm in Durham, New Hampshire, is situated 15 km inland from the Atlantic Ocean. The aerosol chemical composition in this area is dominated by sulfate (SO42−) and ammonium (NH4+) and aerosols that are weakly acidic, most likely because of a lack of regional sources of gaseous ammonia (NH3). Nitrate (NO3−) plays a smaller role in aerosol acidity. The median SO42− aerosol concentration was highest during the summer (23.7 nmol m−3). Inferred fine NO3− concentrations were highest in the winter, with a median concentration of 0.2 nmol m−3. Increased inferred hydrogen ion concentrations and the least neutralized aerosols are associated most strongly with coastal sources, potentially because of smaller NH3 sources relative to sulfur sources in these regions. During the International Consortium for Atmospheric Research on Transport and Transformation (ICARTT) campaign during summer 2004, the composition of fine aerosol was dominated by SO42−, NH4+, and organics. Acidic aerosols sampled during this campaign were largely anthropogenic in origin and photochemically aged.
Trends in aerosol radiative effects over Europe inferred from observed cloud cover, solar “dimming,” and solar “brightening”
Authors: Norris Joel R. , Wild Martin
Published: April 2007

We examine multidecadal changes in surface downward shortwave (SW) radiation flux, total cloud cover, SW cloud effect, and related parameters over Europe during 1965–2004 using monthly gridded data from the Global Energy Balance Archive (GEBA), synoptic cloud reports, and the International Satellite Cloud Climatology Project (ISCCP). One key issue is distinguishing the effects of natural cloud variability from long‐term anthropogenic aerosol influences on surface SW flux. Accordingly, we introduce the concept of cloud cover radiative effect (CCRE), defined as the change in downward SW flux produced by a change in cloud cover. The correlation between pan‐European time series of CCRE anomalies and GEBA solar radiation anomalies is 0.88, indicating that cloud cover variability and associated changes in cloud albedo dominate SW radiation variability on monthly to decadal timescales. After these weather‐related cloud effects are removed by subtracting CCRE anomalies from GEBA solar radiation anomalies via linear regression, a distinct decreasing trend followed by a distinct increasing trend remain in the residual time series. Depending on the method of trend calculation, pan‐European residual flux declined by a statistically significant 2.7–3.5 W m−2 per decade during 1971–1986 and rose by a statistically significant 2.0–2.3 W m−2 per decade during 1987–2002. The fact that independent grid boxes exhibit mostly negative trends in the earlier period and mostly positive trends in the later period demonstrates that these long‐term variations in SW flux are real and widespread over Europe. Changes in cloud cover cannot account for the trends in surface SW flux since cloud cover actually slightly decreased during 1971–1986 and slightly increased during 1987–2002. The most likely explanation is changes in anthropogenic aerosol emissions that led to more scattering and absorption of SW radiation during the earlier period of solar “dimming” and less scattering and absorption during the later period of solar “brightening.”