bluuebunny/crossref_metadata_2025_split huggingface dataset:
Heterogeneity in survival analysis
Authors: Aalen Odd O. 
Published: April 2007

AbstractI discuss the impact of individual heterogeneity in survival analysis. It is well known that this phenomenon may distort what is observed. A general class of mixing (or frailty) distributions is applied, extending a model of Hougaard. The extension allows part of the population to be non‐susceptible, and contains the traditional gamma distribution as a special case. I consider the mixing of both a constant and a Weibull individual rate, and also discuss the comparison of rates from two populations. A number of practical examples are mentioned. Finally, I analyse two data sets, the main one containing data from the Norwegian Cancer Registry on the survival of breast cancer patients. The statistical analysis is of necessity speculative, but may still provide some insight.
Improving the quality of data in randomized clinical trials: The compact computer package. Compact steering committee
Authors: Chilvers C. E. D. , Fayers P. M. , Freedman L. S. , Greenwood R. M. , Machin D. , Palmer N. , Westlake A. J. 
Published: April 2007

AbstractOne crucial component for a successful clinical trial is that the data gathered have a high level of reliability and completeness. This paper reviews some problems of data management and describes the computer package COMPACT which has been developed to deal with such problems. The package allows range and consistency checks and can monitor complex follow‐up schedules. A unique feature of the package is a PROBLEMS file which has use both for identification of queries about the data and of patients with particular characteristics of interest. The ability to monitor drug dosages and to signal deviations from the protocol is of particular value. COMPACT has the syntax necessary to create a ‘flat’ file for transfer to statistical packages for analysis, and the variable description files for SAS, SPSS and MINITAB. The package is written in standard FORTRAN which enables transfer to different types of mini and micro computer systems.
Group sequential procedures: Calendar versus information time
Authors: Lan K. K. Gordon , Demets David L. 
Published: April 2007

AbstractThis paper describes the relationship between information time and calendar time in the use of group sequential procedures to monitor interim analyses of clinical trials. Information time is the proportion of maximum subjects or events already observed. Interim analyses often occur at specified calendar times while the definition of classic group sequential procedures occurs in terms of information time. We extend the general group sequential approach of Lan and DeMets1 to include this situation as well.
A survey of models for repeated ordered categorical response data
Authors: Agresti Alan 
Published: April 2007

AbstractWe survey models for analysing repeated observations on an ordered categorical response variable. The models presented are univariate models that permit correlation among repeated measurements. The models describe simultaneously the dependence of marginal response distributions on values of explanatory variables and on the occasion of response. We present models for three transformations of the response distribution: cumulative logits, adjacent‐category logits, and the mean for scores assigned to response categories. We discuss three methods for fitting the models: maximum likelihood, weighted least squares, and semi‐parametric. Weighted least squares is easily implemented with SAS, as illustrated with a study designed to compare a drug with a placebo for the treatment of insomnia.
Estimation of prevalence on the basis of screening tests
Authors: Lew Robert A. , Levy Paul S. 
Published: April 2007

AbstractEstimates of disease prevalence based on screening tests can be severely biased unless adjusted for the sensitivity and specificity of the screening test. One such adjusted estimate, the maximum likelihood estimator proposed by Levy and Kass, can yield an extreme estimate of zero or one that has undesirable characteristics such as a standard error of zero. We develop here a Bayesian estimator which always falls between zero and one. Users without specialized software can use the maximum likelihood estimate for most circumstances and, in special cases, such as a zero estimate of prevalence, turn to the Bayesian estimate. Others can use software to carry out a complete Bayesian solution. We have provided a method to obtain numerical values for the Bayesian estimate for those ranges of sample size (20–100), sensitivity (07–0.9) and specificity (0.7–0.9) for which the use of this estimator seems most practical.
Does top management team diversity promote or hamper foreign expansion?
Authors: Barkema Harry G. , Shvyrkov Oleg 
Published: April 2007

AbstractPrior research suggests that top management team (TMT) diversity increases strategic innovation. We extended this argument to the case of entering new geographic areas. In addition to exploring the cognitive implications of TMT diversity, as done in prior research, we explored when diversity may lead to the formation of subgroups within TMTs hampering communication and the propensity to enter new geographic areas. We also examined how these positive cognitive and negative social implications change over time as TMT members interact over the years. The hypotheses were tested using ordinal probit analysis and data on 2,159 expansions of 25 companies over a period of more than three decades. Copyright © 2007 John Wiley & Sons, Ltd.
Entry mode and equity level: A multilevel examination of foreign direct investment ownership structure
Authors: Mani Sudha , Antia Kersi D. , Rindfleisch Aric 
Published: April 2007

AbstractOver the last two decades, strategy researchers have sought to understand the ownership structure of firms' foreign direct investments (FDI) as reflected in entry mode and equity level. However, prior FDI research has ignored the interrelated nature of these key FDI decisions. In addition, prior research does not fully account for the fact that individual ownership structure decisions occur within the context of a firm's broader FDI portfolio, and thus reflect a wide and frequently unobserved range of parent firm and host nation effects. Our research seeks to address both of these limitations. Using a rich dataset of 4,459 subsidiaries established by 858 Japanese firms across 38 countries over a 9‐year period, we specify a conditional bivariate, cross‐classified multilevel model of FDI ownership structure. Our model enables the joint estimation of entry mode and equity level, accounts for the portfolio nature of FDI, and compares the relative predictive power of transaction cost‐ and experience‐based explanatory variables across both facets of ownership structure. Copyright © 2007 John Wiley & Sons, Ltd.
XRF analysis of Zn–Fe alloy coatings by using measurements at two take‐off angles
Authors: Kataoka Y. , Kohno H. , Furusawa E. , Mantler M. 
Published: April 2007

AbstractFor the analysis of Fe concentrations and coating weights of galvanneal coated sheet steel, a multichannel x‐ray spectrometer with two element channels featuring a low and a high take‐off angle for Zn K as well as Fe K lines has been developed. For the quantification of coating weights and Fe concentrations a new thin‐film fundamental parameter method has been developed that allows the use of intensity ratios of the Zn K to Fe K lines, for the low as well as the high take‐off angle. The accuracy for Fe concentrations obtained in galvanneal sheet steel coatings is 0.28 mass% and therefore satisfactory for the intended practical application. Among the additional useful features of the spectrometer and the developed fundamental parameter method is the possibility to simultaneously analyze the coating weight of pretreatment layers, such as phosphate, on the Zn‐Fe alloy coating. Copyright © 2007 John Wiley & Sons, Ltd.
Fabrication of array detectors with 100 superconducting tunnel junctions and Ta x‐ray absorbers
Authors: Ukibe M. , Kushino A. , Chen Y. , Ohkubo M. 
Published: April 2007

AbstractWe have developed superconducting tunnel junction (STJ) x‐ray array detectors with a large detection area, high detection efficiency, and high counting rate. The STJ array detectors consist of 100 Nb/Al‐AlOx/Al/Nb STJs with a size of 200 × 200 µm. Each STJ has a 2 µm thick Ta absorber connected to the top Nb layer through a thin insulating layer. The absorbers act as an energy converter from high x‐ray energies to phonon energies, which are compatible with superconducting energy gaps. The array detectors realize a total detection area of 4 mm2 and a detection efficiency of ∼70% for x‐rays of energy up to 6 keV. In addition, it is expected that the spatial uniformity of the x‐ray signal outputs of the Nb‐based STJ by using the Ta absorber may be improved by a fast diffusion of quasiparticles in the Ta absorbers. In order to minimize cross talk, we have adapted a coplanar transmission waveguide (CPW) structure having an 8 µm wide signal Nb line, 7 µm wide ground gaps, 12 µm wide ground Nb lines, and a 50 Ω impedance. The fabrication processes and the detector response to x‐rays are discussed. Copyright © 2007 John Wiley & Sons, Ltd.
Surgical management of intestinal malrotation in adults
Authors: Fu Tao , Tong Wei Dong , He Yu Jun , Wen Ya Yuan , Luo Dong Lin , Liu Bao Hua 
Published: April 2007

AbstractObjectiveThe aim of this study was to review our experience with diagnosis and surgical management of intestinal malrotation in adult patients.Patients and MethodsA retrospective review of the surgical outcome of adults with intestinal malrotation was performed. Twelve patients were observed and treated between July 1996 and July 2006 (4 women and 8 men; the mean age of the patients was 28.5 years). Surgical outcomes, including postoperative complications, deaths, and resolution of preoperative symptoms, were measured.ResultsA diagnosis of malrotation was made preoperatively in five patients by upper gastrointestinal contrast study, barium enema, or computed tomography scan. The anomaly was discovered incidentally at laparotomy in seven patients. All cases were proved to be malrotation intraoperatively. Nine patients underwent laparotomy and three underwent laparoscopic surgery (one converted to an open procedure). Follow‐up ranged from 2 months to 118 months. Three patients had complications: one had wound infection, one had delayed gastric emptying, and one developed adhesive ileus. There were only two recurrences detected and one patient with recurrence required reoperation. No one died.ConclusionsIntestinal malrotation is a rare but important cause of abdominal pain in adults. It may present with chronic or acute symptoms. Laparotomy and laparoscopy are alternative and feasible techniques with low rates of complications for the treatment of intestinal malrotation in adults.
Regionally selective decreases in cerebral glucose metabolism in a mouse model of phenylketonuria
Authors: Qin M. , Beebe Smith C. 
Published: April 2007

SummaryImpairment of cognitive function is characteristic of untreated phenylketonuria in humans and in the pahenu2 mouse model of phenylketonuria. We measured regional cerebral metabolic rate for glucose in the adult male pahenu2 mouse to determine the effect of PKU on functional activity in brain and to discern what, if any, brain areas are affected. Our results demonstrate selective decreases (17–21%) in regions thought to be involved in executive function. Regions most significantly affected include prelimbic, anterior cingulate, orbital frontal and perirhinal cortex. Sensory and motor areas of cortex and hippocampus were remarkably unaffected.
Placebo response in the prophylaxis of migraine: A meta‐analysis
Authors: Macedo Ana , Baños Josep‐E. , Farré Magí 
Published: April 2007

AbstractBackground:Migraine constitutes a good model for the study of placebo response. It is a well‐defined disease, affects a large population and a great number of clinical trials have been performed, which have given homogeneous outcomes.Aim:The aim of this meta‐analysis is to evaluate the placebo response rate in migraine prophylaxis in all published clinical trials since 1988 and to estimate the influence of study design in response variability.Methods:A computer‐based information search was conducted on the Medline database. The outcomes studied were patients who improved (reduction in migraine attacks of 50% or more); attacks per month, and patients with adverse events. Study design and countries in which the study was carried out were also analysed. The meta‐analysis was computed using the Mantel–Haenszel test.Results:In the final analysis, 32 papers were considered. The pooled estimate of the placebo response (patients who improved) was 21%. The placebo response rates were significantly higher in studies with a parallel design than those in cross‐over studies (p<0.01). This response was also higher in European studies than in those performed in North America (p<0.001). Adverse events occurred in 30% of the patients who took a placebo, and the percentage of patients with adverse events was significantly higher in the North American studies than in those conducted in Europe (p<0.01).Conclusion:These data reinforce the need to consider the placebo effect when ascertaining the true therapeutic effect of any drug, as well as to design any clinical trial in the prophylaxis of migraine.
Decreased perceptual learning ability in complex regional pain syndrome
Authors: Maihöfner Christian , DeCol Roberto 
Published: April 2007

AbstractRecently, several functional imaging studies have shown that sensorimotor cortical representations may be changed in complex regional pain syndromes (CRPS). Therefore, we investigated tactile performance and tactile learning as indirect markers of cortical changes in patients with CRPS type I and controls. Patients had significant higher spatial discrimination thresholds at CRPS‐affected extremities compared to both unaffected sides and control subjects. Furthermore, in order to improve tactile spatial acuity we used a Hebbian stimulation protocol of tactile coactivation. This consistently improved tactile acuity, both in controls and patients. However, the gain of performance was significantly lower on the CRPS‐affected side implying an impaired perceptual learning ability. Therefore, we provide further support for an involvement of the CNS in CRPS, which may have implications to future neurorehabilitation strategies for this disease.
Influence of short-term Leucaena leucocephala feeding on milk yield and its composition, thyroid hormones, enzyme activity, and secretion of mimosine and its metabolites in milk of cattle
Authors: GHOSH M. K. , ATREJA P. P. , BURAGOHAIN R. , BANDYOPADHYAY S. 
Published: April 2007

SUMMARYFour Karan/Friesian crossbred (Holstein×Tharparkar) dairy cows in late lactation (>200 days) were fed a basic diet of green maize and concentrates with an increasing proportion of Leucaena leucocephala (leucaena) leaf meal (LLM). The proportion was gradually increased from 0·25 of the dry matter intake (DMI) in the first week to 0·50 in the second, 0·75 in the third and ad libitum in the fourth week. Mimosine, 3,4-dihydroxy pyridine (3,4-DHP) and 2,3-dihydroxy pyridone (2,3-DHP) levels were determined in milk, serum, urine and faecal samples. On average DMI of leucaena was 0·023–0·025, 0·025–0·027, 0·027–0·028 and 0·022–0·025 of live weight (LW) during the first, second, third and fourth week, respectively. Mimosine, 3,4-DHP and 2,3-DHP appeared in the blood serum during leucaena feeding and continued appearing up to sixth week of experimental feeding even after the withdrawal of leucaena from the 34th day onwards. Similarly, excretion of mimosine, 3,4-DHP and 2,3-DHP were observed even after withdrawal of leucaena from the diet. The feeding of LLM resulted in a reduced level of T3 (Triiodothyronine) and T4 (Thyroxine) within a week of LLM feeding. The level of T3 and T4 improved to normal after withdrawal of LLM from the diet. The serum aspartate transferase (AST) and serum alanine transferase (ALT) activities were within the normal range. Leucaena feeding improved milk yield and composition only up to 3 weeks of feeding. The concentration of mimosine, 3,4-DHP and 2,3-DHP in milk was 0·33, 0·05 and 0·02 that of blood, respectively. The secretion of mimosine, 3,4-DHP and 2,3-DHP in the milk might be a concern for health of the offspring of leucaena-fed animals as well as human beings consuming such milk.
Developing a diet authentication system from the composition of milk and meat in sheep: a review
Authors: PRACHE S. 
Published: April 2007

SUMMARYThere is currently an increased consumer demand for information on herbivore production factors, particularly the animal diet. To meet these demands, farmers and commercial entities develop specifications via quality labels. There is therefore a need for analytical tools to be able to guarantee that the specification commitments have been fully met and to help with constructing them. The present paper reviews the current state of knowledge concerning diet authentication in sheep meat and milk, the different approaches that have been investigated, some leading examples concerning the discrimination of contrasting feeding situations in sheep, together with the persistence of some diet markers in the event of changes in animals' diet. The nature of the diet strongly influences the composition of the animal tissues and products, which is due to specific compounds that are directly transferred from the feed to the end product or that are transformed or produced by rumen micro-organisms or the animal's metabolism under the effect of specific diets. Some of these compounds can therefore be used as diet markers. Compounds such as carotenoids, phenolic compounds, fatty acids, volatile compounds and ratios of oxygen, carbon and nitrogen stable isotope are potential tracers in meat and milk or animal tissues of animal feeding diets. Moreover, differences in meat and milk composition induce differences in their optical properties, and therefore in their spectral features, which can also be used for diet authentication. These techniques have already allowed discrimination among products obtained in contrasting feeding conditions. Intermediate situations, for example in case of modification of the animal's diet, may be less easily recognized and may require a combination of tracing methods. In particular, the persistence of tracers when animals are stall-fed a concentrate-based diet after pasture and its implications for traceability are discussed. Finally, further directions for research are highlighted.
The impact of dietary cation anion difference (DCAD) on the acid-base balance and calcium metabolism of non-lactating, non-pregnant dairy cows fed equal amounts of different anionic salts
Authors: Gelfert Carl-Christian , Leonie Loeffler S , Frömer Sven , Engel Maike , Hartmann Helmut , Männer Klaus , Baumgartner Walter , Staufenbiel Rudolf 
Published: April 2007

We evaluated the impact of the dietary cation-anion difference (DCAD) on the influence of anionic salts (AS) on the metabolism of dairy cows using a study-design that included control of feed intake. Ten mature, non-lactating, non-pregnant, Holstein-Friesian-crossbreed cows received 2000 mEq of either one of the seven anionic salts tested, two combinations of the anionic salts or water as control via a rumen cannula. Salts and controls were assigned in a 10×10 Latin square design. Whole blood, serum and urine samples were taken during treatment (TP) and washout period. Samples of whole blood were tested for pH, base-excess and bicarbonate concentrations. In urine, pH and net acid-base excretion (NABE) were analysed. Calcium was measured in serum and urine. According to the different batches of hay, five groups of DCAD were created regarding cluster analysis. Changes in urine and blood parameters were statistically analysed for each DCAD group separately. The different DCAD had an impact on the amount of change in acid-base balance (ABB) and calcium metabolism and for how long these changes lasted. In the DCAD group receiving the highest amount of AS (239 mEq/kg dry matter with AS), changes of ABB were only noticeable in urine and these changes only differed from day zero in the first week of TP (P<0·05). In the other four groups changes of ABB were also visible in blood parameters, but only on a few days of TP did the deviations differ significantly (P<0·05) from day zero. Changes of ABB parameters in urine samples were more pronounced than those in blood and differed clearly from day zero (P<0·05). Parallel to the changes of ABB, calcium concentrations in these samples were significantly increased (P<0·001) in all DCAD groups. Except for the highest DCAD group, ionized calcium concentrations changed over time (P<0·020). However, the differences were very small and only differed from day zero on a few TP days. We conclude that the DCAD of a dairy cow's diet has an important impact on the effect of AS on ABB and calcium metabolism with respect to the duration and amount of change. The target regions of DCAD should be clearly below 100 mEq/kg dry matter to ensure the desired effect on ABB and calcium metabolism. Extremely negative DCAD should be avoided to minimize the risk of clinical acidosis induced by AS.
Differences in susceptibility toMannheimia haemolytica-associated mastitis between two breeds of dairy sheep
Authors: Fragkou Ilectra A , Skoufos John , Cripps Peter J , Kyriazakis Ilias , Papaioannou Nikos , Boscos Costas M , Tzora Athina , Fthenakis George C 
Published: April 2007

We used aMannheimia haemolyticaisolate to study differences in susceptibility to experimental mastitis between two breeds of dairy sheep. The isolate was deposited into the teat duct of Karagouniko (K,n=8) or Frisarta (F,n=8) ewes. The animals were monitored by means of clinical, bacteriological, cytological and pathological methods. K ewes did not develop any systemic or mammary clinical signs, whilst F ewes became ill and developed acute clinical mastitis 12 h later (P<0·001). Bacteria were isolated from 34/48 samples from K ewes and from 46/46 samples from F ewes. Positive California mastitis test (CMT) results were 17/24 samples from K ewes and 23/23 samples from F ewes; leucocytes were seen in Giemsa-stained films. Total pathology score summed over all group K ewes was 41 (maximum possible: 128);Man. haemolyticawas isolated from 12/24 tissue samples. Total pathology score summed over all group F ewes was 93;Man. haemolyticawas isolated from 24/24 tissue samples. Hyperplastic lymphoid nodules consisting of lymphocytes and plasma cells with germinal activity were characteristically present at the border between teat duct–teat cistern of group K ewes; no such structures were observed in teats of group F ewes. The results identified differences in susceptibility/resistance to a mastitis pathogen among animals of the two breeds. Defence mechanisms of the teat appeared to be inadequate against the invading organisms; as lymphoid nodules have been considered important defensive mechanisms of the ovine teat, their observed lack in Frisarta ewes might have predisposed them to development of mastitis.