bluuebunny/crossref_metadata_2025 huggingface dataset:
Geophysical data fusion by fuzzy logic for imaging the mechanical behaviour of mudslides
Authors: Grandjean Gilles , Malet Jean-Philippe , Bitri Adnand , Méric Ombeline
Published: May 2007

Geophysical methods such as seismic surveying or electrical resistivity imaging appear to be well adapted to investigate landslide structure and understand related mechanisms. They allow direct and non-intrusive measurements of acoustic (P), shear (S) waves velocity and electrical resistivity, three physical parameters considered as essential to define the properties of reworked moving materials. Both methods were applied at the “Super-Sauze” site, in the French South Alps, where a typical example of an intra-material mudslide can be observed. Measurements were taken simultaneously along a profile of 325 m in length, perpendicularly to the axis of the mudslide. The P and S-wave velocity fields, as well as the electrical resistivity field, were inverted from recorded data according to suitable algorithms. P and S-wave velocities as well as resistivity tomographies are presented and discussed in term of reliability. Preliminary interpreted results show a correlation between the seismic velocities and electrical resistivity data, confirming that the simultaneous use of both methods gives complementary information on the geomechanical behaviour of the landslide. The seismic data provide information on the variations of fissure density and on the presence of deformed material whereas the electrical resistivity data provide information on the variations of water content within the mudslide. In order to go deeper into the interpretation of the geomechanical behaviour of the mudslide from geophysical data, a data fusion strategy based on fuzzy subsets theory is developed. The computed fuzzy cross-sections show the possibility of geomechanical hypotheses to be realized in specific areas of the tomographic cross-sections highlighting the places where plastic or solid-body deformations could occur. This information is consistent with the geotechnical data and the borehole inclinometer measurements available for the mudslide.
Sediment Phosphorus Extractants for Phosphorus‐31 Nuclear Magnetic Resonance Analysis
Authors: Ahlgren Joakim , De Brabandere Heidi , Reitzel Kasper , Rydin Emil , Gogoll Adolf , Waldebäck Monica
Published: May 2007

The influence of pre‐extractant, extractant, and post‐extractant on total extracted amounts of P and organic P compound groups measured with 31P nuclear magnetic resonance (31P‐NMR) in lacustrine sediment was examined. The main extractants investigated were sodium hydroxide (NaOH) and sodium hydroxide ethylenediaminetetraacetic acid (NaOH‐EDTA) with bicarbonate buffered dithionite (BD) or EDTA as pre‐extractants. Post extractions were conducted using either NaOH or NaOH‐EDTA, depending on the main extractant. Results showed that the most efficient combination of extractants for total P yield was NaOH with EDTA as pre‐extractant, yielding almost 50% more than the second best procedure. The P compound groups varying the most between the different extraction procedures were polyphosphates and pyrophosphates. NaOH with BD as pre‐extractant was the most efficient combination for these compound groups.
Reservoir Sedimentation and Environmental Degradation
Authors: Bennett Sean J. , Rhoton Fred E.
Published: May 2007

Sediments impounded within flood control reservoirs are potentially important archives of environmental and geomorphic processes occurring within drainage basins. The concentrations of select sediment‐associated trace elements were assessed within the impoundment of Grenada Lake, a relatively large flood control reservoir in Mississippi with a history of contaminant bioaccumulation in fish. The post‐construction sediments (after 1954) are discriminated from the pre‐construction sediments (before 1954) based on depth variations in sediment texture and 137Cs emissions. The concentrations of select trace elements of the post‐1954 sediments all are statistically greater than the pre‐1954 sediments, and these same sediments also are enriched in clay. Once these concentrations are normalized by clay content, all trace elements in the post‐1954 sediments are lower in concentration than the pre‐1954 normalized sediments. Moreover, the trace elements when normalized by clay or Al content show virtually no change vertically (over time) within the reservoir impoundment. This suggests that the sources of these sediment‐associated trace elements within Grenada Lake, whether natural or anthropogenic, have not changed appreciably over the lifespan of the reservoir and that the degradation of sedimentologic and ecologic indices within the lake are due to the sequestration of clay or clay‐sized materials.
Cut‐off Net Acid Generation pH in Predicting Acid‐Forming Potential in Mine Spoils
Authors: Liao B. , Huang L. N. , Ye Z. H. , Lan C. Y. , Shu W. S.
Published: May 2007

Acidification of mine wastes can lead to a series of environmental problems, such as acid drainage, heavy metal mobilization, and ecosystem degradation. Prediction of acid‐forming potential is one of the key steps in management of sulfide‐bearing mine wastes. In this paper, the acid‐forming potential of 180 mine waste samples collected from 17 mine sites in China were studied using a net acid generation (NAG) method. The samples contained different contents of total sulfur (ranging from 0.6 to 200 g kg−1), pyritic sulfur (ranging from 0 to 100 g kg−1), and acid neutralization capacity (ANC, ranging from −41 to 274 kg H2SO4 t−1). Samples with high acid‐forming potential are generally due to their high sulfur content or low acid neutralization capacity. After the samples were oxidized by H2O2, the amounts of acid generation and the final NAG pH were measured. Results indicated that the final NAG pH gave a well‐defined demarcation between acid‐forming and non‐acid‐forming materials. Samples with final NAG pH ≥ 5 could be classified as non‐acid‐forming materials, while those with NAG pH ≤ 2.5 could be classified as moderate to strong acid‐forming materials. Materials with NAG pH > 2.5, but < 5, had low risk of being acid‐forming. The confirmation of cut‐off NAG pH will be used as a rapid and cost‐effective operational monitoring tool for the in‐pit prediction of acid‐forming potential of mine wastes and classification of waste types.
Discerning and Modeling the Fate and Transport of Testosterone in Undisturbed Soil
Authors: Fan Zhaosheng , Casey Francis X. M. , Hakk Heldur , Larsen Gerald L.
Published: May 2007

Testosterone is an endocrine disruptor that is released into the environment from natural and anthropogenic sources. The objective of this study was to achieve a better understanding of the complex fate and transport of this labile compound in an undisturbed agricultural soil (a Hamar Sandy, mixed, frigid typic Endoaquolls). This was done by using batch and miscible‐displacement experiments, and by using a chemical nonequilibrium transport model. Sorption and transformations of testosterone were discerned using various batch experiments. The batch experiments indicated that the aqueous phase concentrations of testosterone rapidly decreased from 12 to 15% of the initial aqueous concentration within 5 h, but then gradually increased through time and reached 28 to 29% of the initial aqueous concentration at 168 h. The increase in the aqueous concentration was explained by mineralization and biodegradation. Multiple first‐order models were used to describe batch experiments where simultaneous degradation and sorption processes occurred. An evolutionary global optimization strategy was used to estimate the process parameters from these batch experiments and there was high confidence in these parameter estimates. The result of column experiments also showed that 23.4% of testosterone was mineralized to CO2 as it transported through the column. Combustion analyses of extracted soil from inside the columns showed that most of the 14C retained in the column (69–74%) was sorbed in the top 5 cm. The independently determined batch parameters were incorporated into a chemical nonequilibrium transport model, which provided an excellent description of the hormone in the effluent, and vertical redistribution in the soil column.
Phosphorus removal from soy protein wastewater using novel crystallisation technology
Authors: Wood K. , Wood G. , Prokop D. , Lewyllie F.
Published: May 2007

The objective of this work was to identify and implement a treatment method that would reduce the phosphorus (P) content of soy protein isolate manufacturing wastewater to an average of 2 mg L−1 total P without increasing soluble salts in order to comply with discharge and receiving-water requirements. A novel crystallisation technology was evaluated through pilot studies that demonstrated these objectives could be met. Rapid settling (3.6 cm min−1) and filterable particles (65% filter cake dry solids content) were produced with lime precipitation at 10.0–10.2 pH in the high-aspect ratio, draft tube crystalliser (HARDTAC). Crystal growth in the full-scale system has yielded mean particle sizes of >60 μm. Also, minimal carbonate removal resulted in residual sludge generation of 0.6–0.8 g and lime consumption of 0.40–0.75 g per litre treated, which is substantially less than with a complete softening reaction. This paper describes the technical evaluation and full-scale treatment system that has been in operation since late 2005.
Olive mill wastewater biological treatment by fungi biomass
Authors: Caffaz S. , Caretti C. , Morelli M. , Lubello C. , Azzari E.
Published: May 2007

Olive oil extraction is one of the most important traditional food industries in the Mediterranean region, especially in Italy. In addition to olive oil, this industry produces by-products, in particular olive mill wastewaters (OMWs) and olive husks, which represent a serious environmental problem. OMWs can be rarely treated in a municipal WWTP, using conventional wastewater treatments. A novel biological process has to be considered in order to treat OMWs. Literature data show that yeasts and different kinds of fungi are able to reduce both the organic and the phenolic content of the OMW. The present work is aimed at investigating the growth of a biomass rich in fungi in a batch reactor filled with OMW and its capacity to degrade the organic and phenolic load. The aerobic OMW degradation obtained using this biomass reached a COD and TP removal efficiency of 86 and 70%, respectively. Respirometric tests have been carried out in order to measure the biomass activity on different substrates: OMW and phenolic compounds (gallic and p-coumaric acids). The polyphenolic biodegradation efficiency of fungi biomass was higher than the one of a non-acclimated activated sludge biomass. Fungi biomass was able to completely degrade pure phenolic compounds.
Effects of nitrobenzene concentrations and hydraulic retention time on the treatment of nitrobenzene in sequential anaerobic baffled reactor and continuously stirred tank reactor system
Authors: Selçuk Kuşcu Özlem , Teresa Sponza Delia
Published: May 2007

The effects of increasing nitrobenzene (NB) concentrations and hydraulic retention time (HRT) on the performance of anaerobic baffled reactor (ABR) and aerobic completely stirred tank reactor (CSTR) were studied. In the first step the NB concentration was increased from 30 to 700 mg/L at constant COD and flowrates. Maximum COD removal efficiencies in ABR varied between 88–92% as NB concentrations increased from 30 to 210 mg/L. After this dose, COD removal efficiency decreased to 85 and 79% at NB concentrations of 550 and 700 mg/L, respectively. Removal efficiencies of NB were nearly 100% for all NB concentrations in ABR reactor effluent. In the second step, COD and NB concentrations were kept constant while HRT decreased from 10.38 days to 1 day. As HRT decreased from 10.38 to 2.5 days the COD removal efficiencies in the anaerobic and anaerobic/aerobic reactor effluents were 92–94% and 97–98%, respectively. As HRT decreased from 2.5 days to 1 day COD removal efficiencies in the anaerobic and anaerobic/aerobic reactor effluents decreased to 83 and 95%, respectively. This study showed that HRT is a more important operation parameter than increasing NB concentration in ABR /CSTR sequential reactor system. Although ABR/CSTR system exhibited good COD and NB removal efficiencies, the lower HRTs slightly decreased the removal efficiencies compared to increasing NB concentration.
High-rate sulphidogenic fluidised-bed treatment of metal-containing wastewater at high temperature
Authors: Sahinkaya E. , Özkaya B. , Kaksonen A.H. , Puhakka J.A.
Published: May 2007

The applicability of fluidised-bed reactor (FBR) based sulphate reducing bioprocess was investigated for the treatment of iron containing (40–90 mg/L) acidic wastewater at 65 °C. The FBR was inoculated with sulphate-reducing bacteria (SRB) originally enriched from a hot mining environment. Ethanol or acetate was supplemented as carbon and electron source for the SRB. A rapid startup with 99.9, 46 and 29% ethanol, sulphate and acetate removals, in respective order, was observed even after 6 days. Iron was almost completely removed with a rate of 90 mg/L.d. The feed pH was decreased gradually from its initial value of 6 to around 3.7 during 100 days of operation. The wastewater pH of 4.3–4.4 was neutralised by the alkalinity produced in acetate oxidation and the average effluent pH was 7.8±0.8. Although ethanol removal was complete, acetate accumulated. Later the FBR was fed with acetate only. Although acetate was present in the reactor for 295 days, its oxidation rates did not improve, which may be due to low growth rate and poor attachment ability of acetate oxidising SRB. Hence, the oxidation of acetate is the rate limiting step in the sulphidogenic ethanol oxidation by the thermophilic SRB.
Improved pertubation method for absorption map reconstruction in diffusion optical tomography
Authors: Feng Hua-Cheng , Bai Jing
Published: May 2007

The perturbation method is an effective approach for optical tomography reconstruction, however its success depends to a great extent on how close initial estimates are to the actual solutions. In addition, the linear perturbation method can only be applied to the reconstruction of differences between two similar states. To overcome these limitations, we present a pre-scaling technique applied to the qualitative reconstruction of the absorption map. In this method, the initial estimate of the absorption coefficient is scaled to an appropriate value before it is employed in iteration. The scaled estimate leads to the forward solution on the boundary close to the measured data. In the simulated experiments, reconstructions were performed with and without the pre-scaling technique. The results demonstrate that the proposed technique extends the selection of the initial estimate of optical properties, and makes it feasible that the absolute value of optical properties can also be used in the linear perturbation approach.
Ueber die Nachbildung der natürlichen Heilquellen
Authors: Struve F. A. A.
Published: May 2007

[Die Mineralwässer haben in neuerer Zeit in Deutschland so mannichfache Erörterungen veranlasst und über sie sind zugleich so viele wunderliche Dinge unter das Publikum gebracht worden, dass es wohl ganz zeitgemäss ist, auch einmal hervorzuheben, was hinsichtlich eines der viel bestrittenen Punkte, nämlich der Entstehung der Mineralwässer, die Resultate einer mit Umsicht angestellten Experimentaluntersuchung gelehrt haben. Aus diesem Grunde habe ich mir erlaubt, aus dem so eben von Hrn. Dr. Struve herausgegebenen zweiten Hefte: Ueber die Nachbildung der natürlichen Heilquellen u. s. w., unter Mitwissen des geehrten Verfassers, einen Auszug in die Annalen aufzunehmen, und zwar in grösserer Ausführlichkeit, als es sonst bei einem für sich in deutscher Sprache erschienenen Werke geschehen wäre. Ich habe jedoch nur das herausgehoben, was mit dem genannten Gegenstande in unmittelbarer Beziehung steht, und überlasse den Lesern, die fernerweitigen interessanten Versuche und Betrachtungen des Verfassers im Originale selbst nachzusehen. Auch ist es hier wohl am Ort, die Leser auf die beiden schätzbaren Werke des Hrn. Prof. Bischof: Die Mineralquellen Deutschlands und Frankreichs u. s. w., und: Die Mineralquellen zu Roisdorf u. s. w. (beide Bonn 1826) aufmerksam zu machen, da sie in diesen Mehreres, was unser Verfasser bloss angedeutet hat, näher entwickelt und mit der nöthigen literarischen Nachweisung zusammengestellt finden.]
L1‐logistic Discrimination as Used for Assistance of Medical Diagnosis in Chronic Airways Disease
Authors: Krusińska E. , Liebhart J.
Published: May 2007

The paper presents an application of L1‐logistic discriminant functions to the support of medical diagnosis in so called chronic airways disease which includes bronchial asthma, chronic bronchitis and lung ephysema. It is shown that the L1‐logistic discriminant function is more robust than the classical logistic function and gives higher rate of correctly classified individuals.
A Global Rank Test for Geographical Clusters of Disease
Authors: Möhner M.
Published: May 2007

In the last years a considerable amount of effort has been put into the methodology of mapping and analysis of geographical distribution of cancer incidence or mortality. A test for geographical clusters, taking into account the rank order with respect to the cancer incidence was proposed in the Cancer Atlas of Scotland (KEMP et al. (1985)). But, unfortunately the test requires a time‐consuming simulation for the distribution function of the corresponding test statistics.

In the present paper an easy calculable normal approximation of this rank‐test will be derived. A simulation study for two regions shows that the goodness of approximation is much better than it could be assumed by the corresponding bounds derived by the Berry‐Esseen‐inequality.
Approximate Confidence Interval on Ratio of Two Variances in a Two‐way Crossed Model
Authors: Ting Naitee , Graybill Franklin A.
Published: May 2007

The model considered is a two‐factor cross‐classification variance components model with one observation per cell. Let the two factors be A and B, the problem is to obtain an approximate confidence interval for the ratio of variance component A over variance component B. In this paper, a method of solving this problem is established and simulations are performed to check the method.
A Test for Detecting Overdispersion in Multiple Spell Failure Time Models
Authors: Hamerle A.
Published: May 2007

This paper proposes a test for the detection of the presence of unobserved heterogeneity. The term “unobserved heterogeneity” refers to differences remaining in hazard rates after controlling for the effects of the included covariates. The test relies on results of LANCASTER (1985), and BURDETT et al. (1985). Their results are generalized to allow for multiple spells. No assumption on the functional form of the distribution of the heterogeneity is required. The test statistic can be calculated with available computer programs. In the last section we present an example of the application of the test, analyzing survival data after breast cancer operation.
A Note on Estimation of Several Missing Values in Two Way Classified Data with Many Observations Per Cell
Authors: Subramani J.
Published: May 2007

In this paper an attempt has been made to reduce the computational complexities involved in estimation of several missing values. As a result it has been shown that one can estimate m missing values by developing only k (≤m) linear equations, where m and k are respectively the number of missing values and missing cells. The procedure is also illustrated with the help of a numerical example.
A Test of the Equivalence of Four Random Number Generators – A Simulation Study
Authors: Rovine Michael J. , von Eye Alexander , Jones Constance J.
Published: May 2007

Four pseudo random number generators were tested for equivalence. Using two different seed values for each generator, the robustness of a one‐sample t‐statistic was assessed under a stationary auto‐regressive process. The degree of autocorrelation, sample size and significance level were varied for the eight sets of random numbers generated. Results showed an interaction effect between random number generator and alpha level of the t‐distribution, suggesting that simulation results could depend on the random number generator selected.
Reduction of Total Sample Size and Cost of Sampling in Tests of Hypothesis by Using Unequal Group Sizes
Authors: Trajstman A. C.
Published: May 2007

The standard approach in calculating the appropriate sample size required to detect a specified difference in the means of two populations for given type I and II errors assumes equal sample sizes in each group. It is shown here that equal sample sizes are usually sub‐optimal with respect to total sample size and with respect to total cost of the experiment. This is may be important in experiments involving animals when costs are measured not only in monetary terms but also in terms of animal suffering or inconvenience.
More Parsimonious Linar‐By‐Linear Associatin Model in the Analysis of Cross‐Classifications Having Ordered Categories
Authors: Tomizaawa Sadao
Published: May 2007

For the analysis of cross‐classifications having ordered categories, this paper proposes a model which is more parsimonious than the linear‐by‐linear association (LL) model (that is, which can be described in terms of fewer parameters than the LL model). In a special case, this model is more parsimonious than the uniform association (U) model. Under this model, the expected frequency on a log scale is a linear function of row and column variables for fixed column and row variables, respectively. For the well‐known operation and dumping severity data, the parsimonious U model proposed here fits well, and new interpretations are added.
A Booststrap Adaptive Test for Two‐way Analysis of Variance
Authors: Donegani M.
Published: May 2007

We propose a method to construct adaptive tests based on a bootstrap technique. The procedure leads to a nearly exact adaptive test depending on the size of the sample. With the use of the estimated Pitman's relative efficacy as selector statistic, we show that the adaptive test has a power that is asymptotically equal to the power of it's better component. We apply the idea to construct an adaptive test for two‐way analysis of variance model. Finally, we use simulations to observe the behaviour of the method for small sample sizes.
Response to Selection Under Non‐Random Mating I. Partitioning Genetic Variance
Authors: Muralidharan K. , Jain J. P.
Published: May 2007

In analogy to the concept of breeding value defined for random mating equilibrium populations, the “transmittable genetic value” of an individual is defined as the average value of its expected progeny for any system of mating. The genotypic value is then characterised in terms of transmittable and residual genetic values and components of genetic variance redefined which can be estimated by the conventional procedure based on resemblance between relatives.
On the Boundary Behaviour of Nonparametric Regression Estimators
Authors: Dette H.
Published: May 2007

In this note the nonparametric regression estimators of Nadaraya (1964) and Watson (1964), Priestley & Chao (1972) and Gasser & Müller (1979) are compared with respect to the boundary behaviour in the case of a fixed design. It is shown that the estimator of Nadaraya & Watson yields estimates with smaller mean squared error at the boundary in finite sample situations compared to the convolution type estimators. By a modification of the kernel function the estimator of Gasser & Müller attains a similar boundary behaviour as the Nadaraya & Watson estimator. The theoretical results are illustrated in a simulation study.
Phenotypic Correlation: Its Estimation and Testing Significance
Authors: Sing Murari , El‐Bizri Khaled S.
Published: May 2007

Plant scientists often assess correlation coefficients to develope a selection strategy for better plant type. They generate data on the desired traits on several genotypes grown in a randomized complete block design. Using the data from such experiments, this paper presents the asymptotic standard error of an estimate of phenotypic correlations coefficient and a test of significance. The method is illustrated using data on chickpea crop.
Estimating Growth Reduction Dose for Polynomial Response Relationships
Authors: Singh M. , Haq M. A.
Published: May 2007

Mutation breeders often estimate an irradiation dose which causes a specified reduction in growth of a biological material. In this paper, we estimate the growth reduction dose (GRD) and its confidence interval, when the dose‐response relationship is of a general polynomial form. We make a realistic assumption that the response at the control dose is a random variable. We compare the estimates, standard error and confidence intervals of GRD with those obtained under a situation where response at control dose is a known constant. We illustrate the procedure with data on the effect of gamma irradiation and Ethylmethane sulphate on shoot lengths of chickpea genotypes.
Statistical Comparison of Band Spectral Power: An Aid in Stochastical Analysis of Brain Electrical Activity Part 1: Approximation of the distribution of broad band power by a χ2‐distribution
Authors: Schack B. , Wagner H. , Witte H.
Published: May 2007

In this study the distribution of estimated broad band spectral power is evaluated. Under weak assumptions it is possible to appropriate this distribution by a χ2‐distribution and to construct tolerance intervals with great statistical accuracy. The theoretical results implicate a new methodical basis for statistical comparison of spectral parameters in EEG analysis.
The Error Rate of Tests for Regression Coincidence and Parallelism Under Unknown Multiplicative Heteroscedasticity
Authors: Gregoire Timothy G.
Published: May 2007

The usualFtest of regression coincidence, which is appropriate under a homoscedastic model, is examined under a multiplicatively heteroscedastic model. The departure of the test from its nominal level is slight when the sample of explanatory variables is symmetric, but may be substantially inflated when the sample has positive skew. Conversely, the nominal level may be slightly depressed when the sample has negative skew. The size of the perturbation from the nominal level depends on the degree of heteroscedasticity, however its effect is more pronounced with positively skewed samples. Similar trends are evident for the usualFtest of regression parallelism. There is no apparent pattern to the discrepancy of the level of the test with regard to the data which would permit empirical researchers to adjust their results.
Use of Polytomous Logistic Model in Matched Case‐Control Studies
Authors: Ganguly S. S. , Nimbalkar U. Naik
Published: May 2007

Binary logistic model has been found useful for estimating odds ratio in case of dichotomous exposure variable under matched case‐control retrospective design. We describe the use of polytomous logistic model for estimating odds ratios when the exposure of prime interests, relative to disease incidence, has more than two levels. An illustrative example is presented and discussed.
On a Martingale Approach for the Estimation of the Parameters of a Bivariate Carrier Borne Epidemic Model in Presence of a Linear Relationship Between Carriers and Suspectibles
Authors: Biswas S. , Thomas M.
Published: May 2007

The present investigation is to waive the restriction of PICARD (1980) viz. x0 + y0 = n (the size of the population) for the obvious reason that the size of the susceptible population exposed to risk will depend on the growth rate of carriers and to evolve a simple methodology for the estimation of parameters of Downton's bivariate model. A lienar relationship of Xt on Yt enabled to predict the size of the susceptible population exposed to the risk by a given number of carriers at any time. The same linear equation, when incorporated in Downton's bivariate model has generated the marginal process of Yt. Using several Martingales constructed on the basis of the above marginal process, the minimum number of carriers that can bring out an epidemic and various parameters of Downton's model have been estimated.
An Evaluation of Beta‐Binomial and Dirichlet‐Trinomial Models for the Analysis of Reproductive and Developmental Effects
Authors: Chen James J. , Li Lung‐An
Published: May 2007

The common endpoints for the evaluation of reproductive and developmental toxic effects are the number of dead/resorbed fetuses, the number of malformed fetuses, and the number of normal fetuses for each litter. The joint distribution of the three endpoints could be modelled by a Dirichlettrinomial distribution or by a product of two‐beta‐binomial distributions. A simulation experiment is used to investigate the biases of the maximum likelihood estimate (MLE) for the probability of adverse effects under the Dirichlet‐trinomial model and the beta‐binomial model. Also, the type I errors and powers of the likelihood ratio test for comparing the difference between treatment and control are evaluated for the two underlying models.

In estimation, the two MLE's are comparable, the bias estimates are small. In testing, the likelihood ratio test is generally more powerful under the Dirichlet‐trinomial model than the beta‐binomial model. The type I error rate is greater than the nominal level using the Dirichlet‐trinomial model in some cases, when the data are generated from the two‐beta‐binomial model, and it is less than the nominal level using the beta‐binomial model in other cases, when the data are generated from the Dirichlet‐trinomial model.
An Extended Class of Ranking Models
Authors: Sharma A. , Wolfe D. A.
Published: May 2007

A further enlargement of the class of generalized Mallow's ranking models considered by Fligner and Verducci is proposed. Included in this enlarged class are rank probability distributions other than the uniform that lead to symmetric distributions for many of the common measures used to assess distances between rankings. A particular application to the standard Kendall distance is illustrated in more detail.
Confidence Intervals on Ratios of Variance Components for the Unbalanced Two Factor Nested Model
Authors: Sen Bhabesh , Graybill Franklin A. , Ting Naitee
Published: May 2007

The model considered in this article is the two‐factor nested unbalanced variance component model:
equation image
for p = 1, 2, …, P; q = 1, 2, …, Qp; and r = 1, 2, …, Rpq. The random variables Ypqr are observable. The constant μ is an unknown parameter, and Ap, Bpq and Cpqr are (unobservable) normal and independently distributed random variables with zero means and finite variances σ2A, σ2B, and σ2C, respectively. Approximate confidence intervals on ϱA and ϱB using unweighted means are derived, where
equation image
The performance of these approximate confidence intervals are evaluated using computer simulation. The simulated results indicate that these proposed confidence intervals perform satisfactorily and can be used in applied problems.
An Empirical and Simulated Comparison of Some Tests for Detecting Progressiveness of Response with Increasing Doses of a Compound
Authors: Capizzi Thomas , Survill Tracy T. , Heyse Joseph F. , Malani Hina
Published: May 2007

Experiments consisting of several doses of a test agent and a zero dose control are often conducted to evaluate the effect of a compound on the response of interest. TUKEY et al. (1985) proposed a trend test procedure which uses the minimum p‐value from three candidate dose scalings as a sensitive means for detecting a trend in response with increasing dose. Trend is defined here as a progressiveness, either increasing or decreasing, in response with increasing dose of the test agent. In this paper, we take a closer look at the procedure's inflated type I error rate and propose an adjustment based on the multivariate t‐distribution which preserves the nominal significance level. Application of the adjusted trend test to a number of real data sets indicates that its performance is similar to that observed with Bartholomew's and Williams' tests. An evaluation of these three tests also was conducted on simulated data using an apparently novel approach which takes into account the underlying dosage regimen to genrate the alternative hypotheses for a broad range of dose response relations. The simulation results indicates that the adjusted trend test is overall more powerful than its two competitors, although there are circumstances where each procedure appears superior. This broad‐based power exhibited in both real and simulated settings makes the adjusted trend test an attractive approach.
Monte Carlo Comparison of Multiple Comparison Procedures
Authors: Zieliński Wojciech
Published: May 2007

Seven procedures of multiple comparisons: Tukey, Scheffé, Bonferroni, Studentized Maximum Modulus, Duncan, Newman‐Keuls and F are compared with respect to the probability of the correct decision. Monte Carlo simulation shows that there is no the best procedure.

AMS 1985 Subject Classification: 62 J 15.
Estimation of Design and Genetic Components of Variance in Double Cross Mating Designs
Authors: Ponnuswamy K. N. , Natarajan S. , Subramani J.
Published: May 2007

The present paper deals with the estimation of design and genetic components of variance based on full double crosses and partial tetra‐allel crosses. We have presented the explicit experissions for the symmetric sums estimators of design components of variance based on Hinkelmann's model. Consequently we have also presented explicitly the genetic components of variance based on full double crosses and partial tetra‐allel crosses. The procedure is also illustrated with the help of a hypothetical data.
Robust Umbrella Tests for a Generalized Behrens‐Fisher Problem
Authors: Chen Yuh‐Ing
Published: May 2007

This paper is concerned with testing for umbrella alternatives in a k‐sample location problem when the underlying populations have possibly different shapes. Following CHEN and WOLFE (1990b), rank‐based modifications of the HETTMANSPERGER‐NORTON (1987) tests are considered for both the settings where the peak of the umbrella is known and where it is unknown. The proposed procedures are exactly distribution‐free when the continuous populations are identical with any shape. Moreover, the modified test for peak‐known umbrella alternatives remains asymptotically distribution‐free when the continuous populations are assumed to be symmetric, even if they differ in shapes. Comparative results of a Monte Carlo study are presented.
Confidence Intervals and Tests of Hypotheses on Variance Components in an Unbalanced Two‐fold Nested Design
Authors: Hernandez Ramon P. , Burdick Richard K. , Birch Nancy J.
Published: May 2007

Confidence intervals and tests of hypotheses on variance components are required in studies that employ a random effects design. The unbalanced random two‐fold nested design is considered in this paper and confidence intervals are proposed for the variance components σ2/A and σ2/B. Computer simulation is used to show that even in very unbalanced designs, these intervals generally maintain the stated confidence coefficient. The hypothesis test for σ2/A based on the lower bound of the recommended confidence interval is shown to be better than previously proposed approximate tests.
Using Discrete Distributions to Compute Powers for Goodness‐of‐Fit Test Statistics in a One‐Way Multinomial Setting
Authors: Lawal H. B.
Published: May 2007

Both the Bionomial and Poisson distributions are employed in this study to compute approximate powers for goodness‐of‐fit test statistics. The procedure adopted involves simulating 1000 samples from each of these distributions. These samples are then employed to compute both the randomized nominal critical values and estimated powers. The type I error rates returned from the use of the randomized critical levels Cα fall within the acceptable regions. We illustrate the use of the procedure with the Pearson's X2 test statistic and show that this can readily be extended to any of the other well known goodness‐of‐fit test statistics.
Paradigm Epidemiology?
Authors: Streitberg B.
Published: May 2007

The paper is a first answer to a fundamental critique of epidemiology that has been voiced in a recent book by Immich. Apart from giving an introduction to this important and controversial work, mostly questions of a biostatistical nature are discussed here. A fundamental counter critique from an epidemiological viewpoint is necessary, but is not attempted in this paper.
A Markov Analysis of the Service System for Severe Mental Illness
Authors: Liu Chui‐Yu , Hu Teh‐Wei , Jerrell Jeanette
Published: May 2007

Based on one year of services utilization data in Santa Clara County, we modeled the mental health service system as a time‐continuous Markov process with corresponding Kolmogorov differential equations. The dynamics of the system's operations in that year can be expressed by the results derived from the intensity matrix and the explicit solution of Kolmogorov differential equations. The key problem with the system is linked to its emergency service. An unexpectedly high proportion of patients had a certain period in which they did not receive any services. Most of patients desired more intensive services. Some tentative thoughts about the stabilization of the system are discussed.
A Nonrecursive Estimator for the Cox Model
Authors: Schäbe Hendrik
Published: May 2007

The Cox regression model is one of the most widely used models to incorporate covariates. The frequently used partial likelihood estimator of the regression parameter has to be computed iteratively. In this paper we propose a noniterative estimator for the regression parameter and show that under certain conditions it dominates another noniterative estimator derived by Kalbfleish and Prentice. The new estimator is demonstrated on lifetime data of rats having been subject to insult with a carcinogen.
Approximating the Non‐Null Distribution of the Likelihood Ratio Test Statistic
Authors: Lawal H. B.
Published: May 2007

This paper is concerned with investigation into the behavior of the likelihood ratio test statistic G2 when the alternative hypothesis M (QQ) is the true model. Exact moments of G2 are computed empirically and three approximations are considered for approximating the non‐null distribution of G2. Our results show that the two parameter gamma distribution provides a closer approximation to the exact powers of G2. A randomized procedure was employed to obtain critical values based on 1000 simulated samples.
A Maximum Rank‐Sum Test for One‐Pulse Variation in Monthly Data
Authors: Marrero O.
Published: May 2007

A nonparametric test to detect a pulse in monthly data is presented. This test is a maximum rank‐sum test. The test statistic can be computed from frequencies or rates. The exact null distribution of the test statistic is tabulated for pulses that last 3, 4, 5, or 6 months. Estimates from a simulation study of the test's type I error rate and power are presented. The statistical modeling of the data is discussed. Several examples are given to illustrate the application of the test and the modeling procedures. Practical matters such as the treatment of tied observations, the effect of unequal lengths in the months, sample‐size calculation, and post‐test power analysis are discussed and illustrated with examples.
Probability Model for Crop Yield Forecasting
Authors: Jain R. C. , Agrawal Ranjana
Published: May 2007

Markov chain approach has been adopted to forecast sugarcane yield. Two years data (1977–78 and 1978–79) on biometrical characters and yield collected by IASRI, New Delhi under the pilot study on pre‐harvest forecasting of sugarcane yield in Meerut district (U.P.) were utilised for the study. Yield forecasts at 7–8 months after planting (about 2–3 months before harvest) were very close to the observed ones, per cent deviations from observed being 4% in 1978–79 and 2% in 1977–78. This study thus reveals that Markov Chain method can be successfully used in crop yield forecasting.
Designing Experiments Having Treatments and Covariates
Authors: Lefkovitch L. P.
Published: May 2007

The use of covariates in the designing of experiments having a block and treatment structure is discussed. It is argued that the replicates of each treatment should cover the complete range of each quantitative covariate, so far as is possible. Two optimality criteria are discussed for this purpose, one based on a neighbourhood distance calculated from the means and standard deviations of the covariate, the other based on an extended definition of the canonical efficiencies of the design.
An Annealing Algorithm for Searching Optimal Block Designs
Authors: Jansen J. , Douven R. C. M. H. , van Berkum E. E. M.
Published: May 2007

This paper is concerned with a computer algorithm for searching optimal block designs. The algorithm uses a technique called simulated annealing. Exchange and interchange steps are defined in a way similar to JONES and ECCLESTON (1980). Two examples are used to show the performance of the algorithm.
Imbalance and its Influence on Variance Component Estimation
Authors: Ahrens Heinz J. , Sánchez Jesús E. , Ahrens H. , Sánchez J.
Published: May 2007

A measure of imbalance has been defined for the one‐way classification (Model II) in order to quantify the degree of imbalance. Using the ANOVA and MINQUE procedures we consider the variances and relative efficiencies of the estimators of σ2a as functions of the measure of imbalance. We propose a method for generating all the designs which are possible from a given number of observations and a given number of groups. Numerical results for special types of designs show the influence of imbalance on the variance and relative efficiency of an estimator for σza.
Goodness of Fit Tests for Proportional Hazards Regression Models
Authors: Le Chap T. , Zelterman Daniel , Le Chap T.
Published: May 2007

We present a test of goodness of fit for the proportional hazard regression model. The test is based on a score statistic for testing against local mixture alternatives. Contrary to the findings of several other authors, we detect a significant lack of fit in Freireich's leukemia data.
A Modified “Best Maximum Likelihood” Estimator of Line Regression with Errors in Both Variables: An Application for Estimating Genetic Admixture
Authors: Chakraborty Ranjit , Srinivasan M. R. , Chakraborty Ranajit
Published: May 2007

The problem of estimation when both variables are subject to error in a linear regression model has been discussed in the literature and it has wide applications in econometrics and other social sciences. In this paper we consider the relaxation of the assumption of homoscedasticity and introduce the covariance structure of errors of measurements in the analysis to obtain a Modified Best Maximum Likelihood (MBML) estimator of the regression coefficient.

We also provide an application of the above modification to estimate the extent of genetic contribution of a parental population in an admixed population. With data on frequencies of “unique” African and Caucasian alleles in US Blacks, it is shown that US Blacks have 30.9·2.2 percent genes that are of Caucasian origin.
On the Estimation of the Size of a Finite and Closed Population
Authors: Bolfarine Heleno , Leite José G. , Rodrigues Josemar
Published: May 2007

In this paper, we consider the problem of estimating the size N of a finite and closed population, using data obtained from capture‐recapture experiments. By defining an appropriate model, we investigate the maximum of the likelihood, of the profile likelihood and of an orthogonal adjusted profile likelihood (COX and REID, 1987) function. We show that they all may present infinity as the maximum likelihood estimator of N. This seems to be a characteristic of the likelihood approach in this problem. Further, we present a Bayesian approach with minimum prior information as a way of countering this difficulty. Exact analytical expressions for the posterior modes are also obtained.
On Counts of Organisms Able to Signal the Presence of an Observer
Authors: Kemp A. W.
Published: May 2007

Suppose that organisms occur as entities that are either singlets or doublets, that entities are able to signal to one another the presence of an observer, and that, as a result, they detect the presence of the observer according to a non‐homogeneous birth process. If the behaviour of individuals (and hence their detection by the observer) is thereafter determined by a damage process, the distribution of the number of individuals seen by the observer is found to be a geometric pseudo‐geometric convolution. Properties of the distribution and maximum‐likelihood estimation are described. The model is shown to give a very good fit to the ruffed grouse data of GATES et al. (1968, Biometrics). Variants of the model am discussed.
Theorems on Binary Responses to Combinations of Stimuli
Authors: Drane J. Wanzer , Fu Chongyau , Postelnicu Tiberiu , Drane Prof. J. Wanzer , Fu Chongyau , Postelnicu Tiberiu
Published: May 2007

Binary responses, such as dead or alive, in response to two or more stimuli are considered in this paper. Their joint actions are defined to be either independent, conditionally independent, additive, synergistic or antagonistic. The Bernoulli parameter is replaced by a dose‐response function. Theorems on the probability of a response resulting from the joint actions of the stimuli are stated, and proved. An example is also included.
Handling with Spatial Censored Observations in Statistics of Boolean Models of Random Sets
Authors: Molchanov Ilya S. , Molchanov Ilya S.
Published: May 2007

LetAbe a Boolean model. The existing methods of statistical estimation of its parameters are extended to the case when the observation ofAis spoiled by a certain hindrance. It means that we observe another setA'instead ofA.E.g. the setA′may take the formAorAwhere is a stationary random set (assumed to be hindrance) with a known distribution. This construction generalizes the methods of statistics of censored observations to random sets. A brief description of statistical methods for Boolean models is included. All methods rely on the notion of the empirical capacity functional and use Glivenko‐Cantelli theorem for random closed sets.
Response to Selection Under Non‐Random Mating II. Prediction
Authors: Muralidharan K. , Jain J. P. , Jain J. P.
Published: May 2007

A general expression for response to selection appropriate for both random and non‐random mating situations is derived and illustrated with full‐sibbing.
Subset Selection of an Almost Best Treatment
Authors: Laan Paul Van Der , van der Laan Paul
Published: May 2007

A generalized goal using subset selection is discussed for the location parameter case. This goal is to select a non‐empty subset from a set of k (k ≥ 2) treatments that contains at least one ε‐best treatment with confidence level P*. For a set of treatments an ε‐best treatment is defined as a treatment with location parameter on a distance less than or equal to ε(ε ≥o) from the best treatment, where best is defined as largest value of the location parameter. The efficiency of subset selection of an ε‐best treatment relative to subset selection of the best treatment is investigated and is computed for some values of k and the confidence level for the Normal case as well as for the Logistic case.
Mixed Model Discrete Regression
Authors: Zhaorong J. , McGilchrist C. A. , Jorgensen M. A.
Published: May 2007

Models and estimention procedures are given for linear regression models in discrete distributions when the regression contains both fixed and random effects. The methods are developed for discrete variables with typically a small number of possible outcomes such as occurs in ordinal regression. The method is applied to a problem arising in the comparison of microbiological test methods.