bluuebunny/crossref_metadata_2025 huggingface dataset:
Smoothing
Authors: Kafadar Karen , Horn Paul S.
Published: September 2006

We describe smoothing as an exploratory tool in data analysis, including an underlying model that motivates the need for smoothing, the goals and characteristics of good smoothers, and general classes of smoothers (linear and nonlinear). We also relate smoothing to the concepts of general fitting, parametric and nonparametric regression, and illustrate the use of smoothers on both one‐ and two‐dimensional data sets.
Space Debris Risk
Authors: Brillinger David R.
Published: September 2006

Space debrishas been defined as manmade objects or parts thereof in space that do not serve any useful purpose. There is now a very substantial amount of such ‘space junk’ circling the earth and posing a risk to active and inactive satellites, space stations and spacecraft. This debris presents a problem, with substantial environmental and legal implications. It is yet another pollution problem. This debris has resulted from the more than 3000 space flights that have taken place since 1957. The general concern is risk assessment, that is: estimating the probability of some future event of adverse consequence. In the present circumstance space debris risk assessment might be defined as: The estimation of the probability that certain performance variates of a space object of interest exceed relevant critical levels, within a specified time period, as a result of collisions with space debris.
Spacing Trials
Authors: Burkhart Harold E.
Published: September 2006

One of the most important factors that is within the direct control of managers of plant crops is plant spacing. Managers of agronomic, horticultural, and forestry cropping systems must decide on an initial planting density. Economic considerations dictate that one strives for the ‘optimal’ spacing of plants. The optimum spacing will, of course, vary depending on the management objective. Designed spacing experiments provide reliable information on optimal density for given product objectives.
Spatial Covariance
Authors: Sampson Paul D.
Published: September 2006

Modeling of the spatial dependence structure of environmental processes is fundamental to almost all statistical analyses of data that are sampled spatially. Such analyses address tasks such as spatial estimation (Kriging), monitoring network design (Optimal spatial design), as well as the basic scientific characterization of the second order properties of these processes. This article reviews the current literature under the headings of: smoothing and kernel methods, basis function models, process convolution models, spatial deformation models, and concludes with brief mention of parametric models and further discussion.
Spatial Distribution
Authors: Waller Lance A.
Published: September 2006

Modeling of the spatial dependence structure of environmental processes is fundamental to almost all statistical analyses of data that are sampled spatially. Such analyses address tasks such as spatial estimation (Kriging), monitoring network design (Optimal spatial design), as well as the basic scientific characterization of the second order properties of these processes. This article reviews the current literature under the headings of: smoothing and kernel methods, basis function models, process convolution models, spatial deformation models, and concludes with brief mention of parametric models and further discussion.
Spatial Optimization
Authors: Hof John
Published: September 2006

This article describes an emerging methodology that captures spatial relationships between different land areas in the process of maximizing an objective function subject to resource constraints. It discusses adjacency constraints and direct approaches. Adjacency constraints are utilized when scheduling timber harvests with legal or regulatory restrictions on the effective size of harvest area. Adjacency relationships are important because, for example, if two seemingly legal‐size clearcuts occur within a short time of each other in adjacent areas, then the effective size of the clearcut may not be legal. Direct approaches include the actual ecological spatial relationships of concern. An example is provided that accounts for wildlife habitat fragmentation in optimally placing timber harvests. The land area is divided into cells and choice variables are defined to represent complete scheduled management prescriptions for each cell. Wildlife population levels are then determined by a combination of potential growth, dispersal, and spatially located carrying capacities determined by the management prescription allocations. Other examples of this type of direct spatial optimization are also cited.
Species Overlap
Authors: Gerow Kenneth
Published: September 2006

Species overlap is a concept that sounds simple, yet is elusive to pin down. The simplest measures are based on binary data (presence/absence). Binary indices appeal in that they are usually easy to compute, but suffer several drawbacks, described in this article.
Spectrum Analysis
Authors: Zurbenko Igor G. , Porter P. Steven
Published: September 2006

Time series of environmental quality measurements often display periodic or quasi‐periodic behavior on a wide range of time scales. A clearer understanding of the forces behind these processes may be available through spectral analysis, a transformation of variation in time into variation as a function of frequency or period. This article is intended to introduce an applied scientist to spectral analysis. Spectral analysis of stationary time series is briefly described, and avenues for the exploration of nonstationary time series, which represent the vast majority of time series encountered in practice, are suggested.
S‐PLUS
Authors: Storvik Geir
Published: September 2006

S‐PLUS is an integrated suite of software facilities for data analysis and graphical display. It is an enhanced, supported superset of the S language developed at AT&T Bell Laboratories. It contains standard statistical tools such as linear regression and smoothing, analysis of variance, generalized linear models, multivariate analysis, time series analysis, survival analysis and quality control charts. In addition, many complex, modern techniques are included. Further, it offers a language for expressing statistical models and tools for using linear, generalized linear and nonlinear statistical models.
Standard Error
Authors: Hughes‐oliver J.M.
Published: September 2006

The standard error (se) of a sample statistic is a measure of the variability of the statistic around its ‘typical’ value. The precise definition of se is, however, not universally agreed upon. Suppose

T
X

,
n

 ≡ 
T
(
X
1
, …,
X
n
) is the statistic of interest calculated from the sample
X
1
,…,
X
n
. The se of the statistic
T
is sometimes defined as the standard deviation (sd) of the distribution of
T
and at other times as the estimated sd of the distribution of
T
. The latter definition is also often referred to as the estimated se. Understanding se clearly requires understanding sd.
Standards, Environmental
Authors: Barnett Vic , Bown Marion
Published: September 2006

This article aims to describe the past, present and future techniques by which environmental standards are set. Recent concern regarding the lack of acknowledgment of uncertainty and variability in many standards, and thus in reported results on compliance, has lead to an emphasis on the role of statistical methodology in environmental standard‐setting. Research into the feasibility, advantages and disadvantages of such methodology is on going, but much remains to be done. Encompassing within its line of investigation toxicology, environmental sampling methodology and spatio‐temporal modeling, etc. and affecting the fundamental procedures of industry, traffic management, medical and environmental agencies, etc., to name just a few of many, this area of the rapidly growing field of environmetrics may prove to be one of the most far‐reaching and important statistical applications in the coming years.
State‐Space Methods
Authors: Koopman S.J.
Published: September 2006

The state space model provides an unifying framework for analyzing time series. For the classical Box–Jenkins analysis, state space methods are useful when estimating the autoregressive and moving average coefficients by exact maximum likelihood and when missing values are present. In the case of unobserved components time series models with interpretable components such as trend, seasonal, cycle and irregular, state space methods provide the tools for estimation, signal extraction and diagnostic checking. Indeed, all linear time series models can be cast into state space including dynamic regression models and cubic spline smoothing models.
Statistical Computing in Environmental Science
Authors: Stein Alfred
Published: September 2006

Environmental modeling can be distinguished into
modeling
the environment or some of its compartments,
predicting
environmental parameters, and
storing
and
monitoring
data on the quality of the environment. Computational aspects of environmental science concern data storage, modeling of processes, modeling of effects, graphical display of spatial data and scenario analysis. Computers and computing enter environmental sciences actively and outside research when decision making has to be supported. This requires reliable spatial data, reliable models and interactive tools for visualizing scenarios.
Modeling, Stochastic
Authors: Christakos George
Published: September 2006

Perceptions regarding the meaning of the term stochastic modeling (SM) are not as uniform as one might think. This should not come as a surprise, in view of the multidisciplinary nature of environmental health science. Depending on the application considered, one may refer to stochastic models as environmental, ecologic, genetic, epidemiologic, medical, etc. A common factor in all these cases is that SM is concerned with the mathematically rigorous and scientifically meaningful representation, explanation, and prediction of natural phenomena (physical, biological, etc.) in uncertain environments. Uncertainty may be due to measurement errors, heterogeneous databases, erratic biologic fluctuations in space/time, insufficient knowledge, etc. Within such a framework, SM seeks to provide a realistic environmental situation with spatio‐temporal continuity and internal consistency.
Subjective Probability
Authors: O'Hagan A.
Published: September 2006

Subjective probability
is an alternative definition to the mathematical notion of probability that is adopted by most statisticians who advocate Bayesian methods, and is applicable in many situations where frequency probability cannot be defined.
Subset Selection
Authors: Van Der Laan Paul
Published: September 2006

Assumek(k ≥ 2) populations are given. The associated independent random variables have continuous distribution functions differing only in their unknown location parameter. The statistical selection goal of subset selection is to select from the given set ofkpopulations a non‐empty subset of these populations so that the selected subset includes with confidence levelP*, withk−1 < P* < 1, the best population. In this context, best population means the population with the largest value of the location parameter. The subset selection approach is described in some detail and some properties are presented.
Surveillance, Environmental
Authors: Järpe Eric
Published: September 2006

During most of the previous century, there was a great need for surveillance (also called quality control) methods from the manufacturing industry. Through the last few decades, however, the picture has changed. The demands for surveillance methods from other applications have increased. In order to take appropriate actions to prevent pollution and other environmental deterioration, fast and accurate indications about when a systematic change in an environmental system occurs is crucial. The subject‐matter application determines which models are appropriate, and what properties of surveillance methods that are especially important. For this purpose it is necessary to monitor relevant environmental processes for treatment in time and space.
Survival Analysis
Authors: Andersen Per Kragh
Published: September 2006

A brief review of survival analysis is given. Emphasis is on the need for special methods due to the incompleteness of typical data caused by censoring.
Switching Process
Authors: Shumway Robert H.
Published: September 2006

Often, there is a need to develop models that describe environmental processes that change regimes at unknown points in time or space. Dynamic regression or state–space models that are switching from one regime to the other according to an evolving stationary discrete state Markov chain have great potential for modeling changing environmental phenomena. Processes that involve these kinds of models are often referred to as
switching processes
or hidden Markov processes.
Teratogenesis, Environmental
Authors: Coull Brent A. , Holmes Lewis B.
Published: September 2006

Teratogenesis is defined as the induction of malformations or defects in fetuses during gestation or at birth. As one might expect, induction of birth defects is a major public health concern. Many of these birth defects are attributed to the process of multifactorial inheritance in which both genetic and nongenetic factors are presumed to be involved. Unfortunately, the large majority of the nongenetic factors remain unidentified.
Tree‐Structured Methods
Authors: Leblanc Michael
Published: September 2006

Tree‐structured methods are a class of adaptive statistical procedures used for exploratory data analysis and classification. An important feature of tree‐structured models is that they yield results that can be expressed as a binary decision tree which can often facilitate data exploration.
Trend Analysis
Authors: Harvey Andrew
Published: September 2006

The question of defining a trend is one which has exercised the minds of statisticians for many years. In much of the statistical literature, a trend is conceived of as that part of a series which changes relatively slowly over time. Viewed in terms of prediction, the estimated trend is that part of the series which when extrapolated gives the clearest indication of the future long‐term movements in the series. Trend analysis is best carried out by means of unobserved‐component, or structural, time‐series models. The trend components in structural time‐series models are always set up in such a way that their forecast functions indicate the long‐term movements in the series, and the trend within the series can be obtained by signal extraction methods.
Trend, Detecting
Authors: Woodward Wayne
Published: September 2006

Detecting trend in time series data is a very difficult problem in practice. While there are a variety of definitions of ‘trend’, this article primarily deals with the issue of making a decision concerning whether an apparent trend is due to a deterministic trend component in the data, for example line, polynomial, etc. or is due to temporary random trending behavior.
Trimming and Winsorization
Authors: Horn Paul S. , Kafadar Karen
Published: September 2006

Frequently, a sample may contain observations that differ substantially from the other data values. There are various ways to deal with the possibility of such values so that the resulting analysis will not be adversely affected if they are present. All of these methods assign weights to observations according to some well‐conceived algorithm. In this article we concentrate on two forms of assigning weights to observations. The first is trimming, which corresponds to assigning zero weight to a prespecified fraction of the extreme observations and equal weights to the rest. The second is Winsorizing, which also assign zero weights to the extreme observations, as in trimming, but assigns extra weight to the most extreme observations in the retained sample. In this article we will define these concepts for a single sample of observations, and briefly discuss the applications to more complex problems like regression.
Weighted Distributions
Authors: Patil G.P.
Published: September 2006

Traditional environmetric theory and practice have been occupied largely with randomization and replication. But in environmental and ecological work, observations also fall in the nonexperimental, nonreplicated, and nonrandom categories. The problems of model specification and data interpretation then acquire special importance and great concern. The theory of weighted distributions provides a unifying approach for these problems. Weighted distributions take into account the method of ascertainment, by adjusting the probabilities of actual occurrence of events to arrive at a specification of the probabilities of those events as observed and recorded. Failure to make such adjustments can lead to incorrect conclusions.
Zero‐Inflated Data
Authors: Tu Wanzhu
Published: September 2006

As its name suggests, zero inflation indicates that a dataset contains an excessive number of zeros. The word
inflation
is used to emphasize that the probability mass at the point zero exceeds that allowed under a standard parametric family of distributions. Zero‐inflated data are abundant in many disciplines, including the environmental sciences. If not properly modeled, the presence of excess zeros can invalidate the distributional assumptions of the analysis, jeopardizing the integrity of the scientific inferences. The zeros can also create many computational difficulties. Recently, a fair amount of interest has concentrated on the analysis of zero‐inflated Poisson (ZIP) counts. Strictly speaking, however, the data need not follow a Poisson distribution in order to be zero inflated. In this article, a broader definition of the subject is taken; zero inflation is considered as a practical data phenomenon that can be associated with any parametric family of distributions.
Analysis of the 5HT‐2A T102C receptor polymorphism and psychotic symptoms in Alzheimer's disease
Authors: Craig David , Donnelly Caroline , Hart Dominic , Carson Robyn , Passmore Peter
Published: September 2006

Although the aetiology of psychotic symptoms in Alzheimer's disease (AD) is multi‐factorial, alterations in serotonergic neurotransmission are often implicated. Polymorphisms of the serotonin receptor 5HT‐2A are associated with hallucinatory symptoms and delusions in demented and non‐demented cohorts. This study examined the role of the 5HT‐2A T102C polymorphism in influencing psychotic symptoms in a large Northern Ireland AD population (n = 406, mean MMSE 13/30). Forty‐eight percent of patients experienced delusional symptoms and 28% experienced hallucinations during the course of their dementia. No significant association was found either in frequency of genotype or allelic variation for either set of symptoms. Furthermore, the mean delusional and hallucinatory severity scores did not differ significantly among the three genotype groups. The lack of influence of the T102C polymorphism of the 5HT‐2A receptor on the emergence of psychotic symptoms in AD contrasts with previous reports in other cohorts involving smaller numbers of subjects. © 2006 Wiley‐Liss, Inc.
Simulation of an all‐β3‐icosapeptide containing the 20 proteinogenic side chains: Effect of temperature, pH, counterions, solvent, and force field on helix stability
Authors: Trzesniak Daniel , Jaun Bernhard , Mathad Raveendra I. , van Gunsteren Wilfred F.
Published: September 2006

Simulations of various β‐peptides have in the last years clarified several issues concerning peptide folding equilibria and interpretation of experimental data, especially from NMR and CD spectroscopy. These simulations involved different temperatures, pH‐values, ionic strengths, solvents, and force‐field parameters, but a variation of these factors for one β‐peptide has not yet been done. To investigate the influence of varying these factors, we analyze the helix stability of an all‐β3‐icosapeptide bearing all 20 proteinogenic amino acid side chains, which is experimentally observed to fold into a 314‐helix in methanol but not in water. Structural aspects, such as hydrogen‐bonded rings and salt bridges, are discussed and a comparison with NMR primary (NOE distance bounds and 3J‐values) and secondary (NMR derived model structures) data is made. We further investigate the reasons for the 314‐helix stability/instability in methanol/water. Of all factors studied, the presence of counterions seems to be the one inducing most significant effects in the simulations. © 2006 Wiley Periodicals, Inc. Biopolymers 83: 636–645, 2006

This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com
Meta-analysis of endoscopy and surgery versus surgery alone for common bile duct stones with the gallbladder in situ
Authors: Clayton E S J , Connor S , Alexakis N , Leandros E
Published: September 2006

Background

There is no clear consensus on the better therapeutic approach (endoscopic versus surgical) to choledocholithiasis. This study is a meta-analysis of the available evidence.

Methods

A search of the Medline and ISI databases identified 12 studies that met the inclusion criteria for data extraction. The analysis was performed using a random-effects model. The outcome was calculated as an odds ratio (OR) or relative risk (RR) with 95 per cent confidence intervals (c.i.).

Results

Outcomes of 1357 patients were studied. There was no significant difference in successful duct clearance (OR 0·85 (95 per cent c.i. 0·64 to 1·12); P = 0·250), mortality (RR 1·79 (95 per cent c.i. 0·66 to 4·83); P = 0·250), total morbidity (RR 0·89 (95 per cent 0·71 c.i. to 1·13); P = 0·350), major morbidity (RR 1·34 (95 per cent c.i. 0·92 to 1·97); P = 0·130) or need for additional procedures (OR 1·37 (95 per cent c.i. 0·82 to 2·29); P = 0·230) between the endoscopic and surgical groups. There was also no significant difference between the endoscopic and laparoscopic surgery groups.

Conclusion

Both approaches have similar outcomes, and treatment should be determined by local resources and expertise.
Validation of a tool for identifying women at high risk for hereditary breast cancer in population‐based screening
Authors: Hoskins Kent F. , Zwaagstra Alice , Ranz Michael
Published: September 2006

BACKGROUND

Recent scientific advances provide the opportunity to identify women in the general population at increased breast cancer risk and to offer effective early detection and disease prevention interventions.

METHODS

A pedigree assessment tool (PAT) was designed to identify women in primary care settings who are at increased risk for hereditary breast cancer, including potential BRCA mutation carriers. The PAT is a simple point‐scoring system based on family cancer history with points weighted to account for features associated with a higher probability that a BRCA mutation is present. The ability of the PAT and the Gail model to accurately identify potential BRCA mutation carriers in 3,906 women without a personal history of breast cancer presenting for a screening mammogram at a community hospital was tested.

RESULTS

Eighty‐six (2.2%) women had a family history indicative of a high probability (>10%) that a BRCA mutation was present within the family. The PAT performed better than the Gail model in correctly assigning women to the “high BRCA probability” cohort. The area under the receiver operating characteristic (ROC) curve for the PAT was 0.9625 compared with 0.389 and 0.5861 for the Gail model 5‐year and lifetime risk estimates, respectively. At the optimal threshold score, the PAT performed with 100% sensitivity and 93% specificity.

CONCLUSIONS

The PAT is a simple and accurate tool for identifying women at risk for the hereditary breast cancer syndromes that can be employed as part of a comprehensive breast cancer risk‐screening strategy in the primary care setting. Cancer 2006. © 2006 American Cancer Society.
Clinical factors affecting acquired resistance to gefitinib in previously treated Japanese patients with advanced nonsmall cell lung cancer
Authors: Segawa Yoshihiko , Hotta Katsuyuki , Umemura Shigeki , Fujiwara Yoshiro , Shinkai Tetsu , Ueoka Hiroshi , Takigawa Nagio , Tabata Masahiro , Kiura Katsuyuki , Tanimoto Mitsune
Published: September 2006

BACKGROUND.

The risk factors for the development of acquired resistance in nonsmall cell lung cancer (NSCLC) patients responding to gefitinib are unclear. The current study assessed clinicopathologic factors affecting acquired resistance to gefitinib in previously treated patients with advanced NSCLC.

METHODS.

Between 2000 and 2004, 197 consecutive Japanese patients with advanced NSCLC underwent treatment with gefitinib. Of these patients, 56 who had continued gefitinib treatment without disease progression for at least 6 months were included in the study.

RESULTS.

At a median follow‐up time of 21.6 months (range, 7.7–59.7 months), the median time to disease progression was 19.5 months, with progression‐free survival rates of 68.5% at 1 year, 33.6% at 2 years, and 21.2% at 3 years. In a multivariate analysis using a Cox regression model, baseline brain metastasis was the strongest prognostic factor affecting acquired resistance to gefitinib (hazards ratio, 2.14; 95% confidence interval, 1.10‐ 4.17 [P = .025]). In addition, a decreased baseline hemoglobin level (P = .074) and the administration of >1 chemotherapy regimen before gefitinib treatment (P = .069) tended to be significant negative prognostic factors.

CONCLUSIONS.

In patients undergoing treatment with gefitinib, the presence of brain metastasis was strongly associated with the emergence of acquired resistance in the current series of NSCLC patients. The finding requires confirmation in a large cohort of patients with advanced NSCLC, including a non‐Japanese/Asian population. Cancer 2006. © 2006 American Cancer Society.
Nitrogen‐doped zirconia single crystals
Authors: Rödel T.‐C. , Wang D. , Su D. S. , Lerch M. , Prokofiev A. , Luther K. D. , Assmus W.
Published: September 2006

The aim of this work is the preparation of nitrogen‐doped single crystals of cation‐stabilized zirconia. Thin plates of these crystals were nitrided in a graphite heated resistance furnace with nitrogen as reaction gas. Several dwell times and reaction temperatures were tested and their effect on the amount of incorporated nitrogen is investigated. During nitridation at high temperatures a rock salt‐type ‘ZrN’ layer grows on the surface, leading to the destruction of the crystal. In contrast to the fluorite‐type bulk material, which can be described as a fast anion conductor, the surface layer shows electronic conductivity. For possible applications of the bulk material (solid electrolyte) the formation of the surface layer must be avoided. Therefore, the interface between surface epilayer and bulk material was investigated in detail by electron microscopy methods. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Distribution of metallic ions in a single KDP crystal grown from aqueous solution
Authors: Maeda Kouji , Tabuchi Ryo , Asakuma Yusuke , Fukui Keisuke
Published: September 2006

A single KDP (potassium dihydrogen phosphate) crystal was grown in a supersaturated solution containing a metallic ion (Al3+, Fe3+, or Cr3+). The growth rate, morphology, and distribution of the metallic ions into the KDP crystal were measured as the ionic concentration and supersaturation in the solution changed. It was found that in the KDP crystal, Al3+ and Fe3+ were greatly concentrated, but Cr3+ was diluted. Complete expressions for the effect of metallic ions on all aspects of the growth of KDP crystal were suggested. The growth rates of (100) and (101) faces were well correlated by the empirical equation and resulted in good estimation of morphology. The distribution of metallic ions into KDP crystal was also correlated by the distribution model. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Morphologies of calcium carbonate crystallites grown from aqueous solutions containing polyethylene glycol
Authors: Xie An‐Jian , Zhang Chun‐Yan , Shen Yu‐Hua , Qiu Ling‐Guang , Xiao Pei‐Pei , Hu Zhao‐Yang
Published: September 2006

Calcium Carbonate has been precipitated from aqueous solutions containing different concentrations and different molecular weight of Polyethylene Glycol (PEG). The precipitations were analyzed by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT‐IR) and X‐ray diffraction (XRD). The results demonstrated that PEG has profound influence on the nucleation and crystal growth of CaCO3, under condition of low PEG6000 (refer to PEG MW=6000) concentration, it favored the formation of calcite, while high PEG6000 concentration promoted vaterite formation. Additionally, low molecular weight PEG can stabilize vaterite phase. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Evaporation induced diameter control in fiber crystal growth by micro‐pulling‐down technique: Bi4Ge3O12
Authors: Chani V. , Lebbou K. , Hautefeuille B. , Tillement O. , Fourmigue J.‐M.
Published: September 2006

Diameter self‐control was established in Bi4Ge3O12 fiber crystal growth by micro‐pulling‐down technique. In accordance with Bi2O3‐GeO2 phase diagram, the diameter was controlled due to compensation of solidification with evaporation of volatile Bi2O3 self‐flux charged into the crucible with excess. The crucibles had capillary channels of 310 or 650 μm in outer diameter. The crystals up to 400 mm long and 50‐300 μm in diameter were grown at pulling‐down rates of 0.04‐1.00 mm/min. The melt composition and the pulling rate were generally only two parameters determining solidification rate. As a result, crystals with uniform (± 10%) diameter and aspect ratio up to 104 were produced without automation of the process. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Characterization of olivine single crystals grown by the micro‐pulling‐down method and terrestrial olivine by XPS, Mössbauer, magnetic and EPR methods
Authors: Talik E. , Zarek W. , Kruczek M. , Ganschow S. , Skrzypek D. , Popiel E.
Published: September 2006

The chemical composition, crystal and electronic structure and magnetic properties of the (Mg1‐x Fex )2SiO4 olivines (nominal x=0.060 and 0.091), synthetic and terrestrial (Lower Silesia, Poland) were investigated by X‐ray diffraction, photoelectron and Mössbauer spectroscopy, electron spin resonance and magnetostatic methods. It was found that in synthetic olivines the carbon, proceed from starting materials, located in the Mg sites lead to distortion of the crystal lattice. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Spontaneous crystallization of potassium chloride from aqueous and aqueous‐ethanol solutions; Part 3: Model of the crystallization process
Authors: Linnikov Oleg D.
Published: September 2006

A model of spontaneous crystallization process was proposed. The model describes kinetics of the crystallization process after the end of the induction period. To test the model the published earlier data on crystallization and aggregation kinetics of potassium chloride at its spontaneous crystallization from supersaturated aqueous and aqueous‐ethanol solutions were used. It was found excellent coincidence of the experimental and theoretical data on concentration of the salt and the total number of crystals in solution at crystallization. Somewhat change for the worse was at the theoretical calculations of crystal size distribution at the end of the crystallization process. It indicated that the ways of calculation of size of crystals and their weight fraction in deposit were very approximate. The model allows predicting with satisfactory accuracy kinetics of crystallization using such general parameters of potassium chloride as the specific surface energy and the height of the nucleus‐bridges between crystals at coalescence. It needs further test of the model for other salts. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the crystallochemical origin of the disordered form of Ba7(EuII)F12Cl2 and the structural changes induced at high temperature
Authors: Kubel F. , Hagemann H.
Published: September 2006

The crystal structure of the disordered modification of Ba7F12Cl2 has been carefully re‐examined on several new crystals prepared under different conditions of synthesis. All single crystal structure refinements reveal a residual electron density of ∼3 e–/Å3 in the 0,0,0 position which is explained by the introduction of a small amount of sodium ions in the crystal. The title compound transforms from a disordered to an ordered modification at ∼800 °C. New structural data show a change in space group from P63/m to P6. During this process, a slight chemical change and the formation of nano‐channels in the crystals is observed by electron microscopy. These changes were further studied by electron microprobe analysis, by spectroscopic methods and thermal analysis. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Physical properties of Dy and La doped SnO2 thin films prepared by a cost effective vapour deposition technique
Authors: Joseph J. , Mathew V. , Abraham K. E.
Published: September 2006

Stannous oxide (SnO2) thin film is one of the most widely used n‐type transparent semi‐conductor films in electronics, electro‐optics and solar energy conversion. By achieving controlled non‐stoichiometry, we can get good transparency and high electrical conductivity simultaneously in SnO2 thin films. Dy and La doped SnO2 thin films have been prepared by a cost effective vapour deposition technique. The structural, photo‐electronic, optical and electrical properties of the doped and undoped films were studied. The results of X‐ray Diffraction studies reveals the polycrystalline nature of the films with preferential orientation along the (101), (211) and (301) planes and their average grain size variation for different deposition temperature. Photoconductivity and Photovoltaic studies of the films were also performed. The optical properties of these films were studied by measuring their optical transmission as a function of wavelength. The optical transmission is found to be increased on Dy doping and decreased on La doping. The band gap, refractive index and thickness of the films were calculated from U‐V transmittance and Absorption graphs. The optical band gap of undoped film is found to be 4.08 eV, but on doping it shifts to lower energies and then increases on increasing the concentration of both dopants. Its electrical parameters such as sheet resistance, resistivity, mobility, Hall coefficient, and carrier concentration were determined by Four Probe, Van der Pauw and Hall Probe method. On doping with Dy, carrier conversion takes place from n‐type to p‐type and p‐conductivity dominates. On La doping no carrier conversion takes place but resistivity decreases. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Growth and characterisation of potassium cobalt nickel sulfate hexahydrate for UV light filters
Authors: Zhuang Xinxin , Su Genbo , He Youping , Zheng Guozong
Published: September 2006

A new single crystal for ultraviolet light filter, KCNSH (Potassium Cobalt Nickel Sulfate Hexahydrate) was designed and its crystal structure was studied using X‐ray diffraction in this paper. The empirical of the title compound is K2Co0.1Ni0.9(SO4)2.6H2O with formula weight 437.15. KCNSH crystal belongs to the monoclinic space group P2(1)/c, a=6.1390(3)Å, b=12.1839(6)Å, c=9.0095(4)Å, α=γ=90°, β=105.060(2)°, V=650.74(5)Å3, Z=2, Dc=2.231g/cm3. Using the cooling solution method, we have grown a deep green KCNSH crystal with dimension of 12×12×40mm3. The transmission spectrum of KCNSH in the range from UV to near IR wavelengths, its thermal properties, and the relationship between the structure and optical transmission properties are also studied and further discussed in this paper. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
An X‐ray powder diffraction study of the microstructural evolution on heating 3:2 and 2:1 mullite single‐phase gels
Authors: Ruiz de Sola E. , Serrano F. J. , Torres F. J. , Reventós M. M. , Esteve V. J. , Kojdecki M. A. , Amigó J. M. , Alarcón J.
Published: September 2006

Single‐phase gels with compositions 3Al2O3·2SiO2 and 2Al2O3·SiO2 were prepared by gelling mixtures of aluminium nitrate and tetraethylorthosilicate. Gels were fast heated at different temperatures between 900°C and 1600°C. The phase transformation and microstructural changes of both mullite precursor gels over the temperature range were followed by X‐ray powder diffraction (XRD), lattice parameter determination (LP), and scanning and transmission electron microscopies (SEM and TEM). The distribution of crystallite sizes and strains were determined by linewidth refinements of X‐ray diffraction patterns using the integral breadth method of Langford and the Warren‐Averbach analysis. XRD of both heated gels showed the formation of crystalline mullite single phase. Some amount of glassy phase coexisted with mullites at low temperatures, i. e. below 900°C. The compositional range of mullites formed on heating gels at temperatures between 900°C and 1600°C was dependent on the starting nominal composition of gels. SEM and TEM micrographs of both heated gels below 1200°C showed the formation of small, discrete, prismatic, well‐shaped nanocrystals in a very ordered arrangement. The size of these nanocrystals was dependant on the nominal composition of gels and increased on rising the heating temperature of gel precursors. The microstructural features obtained from linewidth refinement results of X‐ray diffraction patterns also allowed to suggest the formation of prismatic a little elongated nanocrystals at temperatures below 1200°C. Microstrain values were small and only displayed a relatively significant value for mullites processed at 900°C. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Two CrIII containing metal‐1‐hydroxyethylidenediphosphonate compounds: Synthesis, structure, and morphology
Authors: Wu Zongbin , Liu Zhongmin , Tian Peng , Xu Lei , Song Haibin , Bao Xinhe , Liu Xiumei , Liu Xianchun
Published: September 2006

Two novel layered CrIII containing metal‐hedp compounds, Na20AlCrIII[CH3C(O)P2O6]6·O3·(H2O)26·(H3O)10 (CH3 CH2 OH) and Na6CrIII[CH3C(OH)P2O6]3·(H2O)21(H3O)3 (designated as DLES‐AlCr and DLES‐CrIII respectively), were hydrothermally synthesized. Their structures were determined by single‐crystal X‐ray diffraction. The two crystals are isostructural with propeller‐like chiral motifs and hexagonal rings along [001]. DLES‐AlCr crystal exhibits interesting hollow tubular hexagonal morphology, while DLES‐Cr crystal possesses solid hexagonal morphology. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Laser scanning cytometry in the characterization of the proapoptotic effects of transiently transfected genes in cerebellar granule neurons
Authors: Bingham Brendan , Kotnis Smita , McHendry‐Rinde Barbara , Shen Ru , Wood Andrew , Kennedy Jeffrey D.
Published: September 2006

Background

Low transient transfection efficiency limits the ability to characterize putative proapoptotic gene function in neurons. Laser scanning cytometry (LSC), with its high capacity, medium throughput means of collecting fluorescent emissions from cultured cells, offers an effective technology for scoring cell death in neuronal transfectants.

Methods

Cerebellar granule neurons (CGNs) were transfected with EGFP‐fusion constructs of Caspase‐3 and Caspase‐9 using a DNA‐calcium phosphate coprecipitation method. CGNs were fixed, permeablized, and stained with propidium iodide (PI) nuclear dye. An LSC method, based on a combination of Long Red Max Pixel, Long Red Integral, and Green Integral fluorescence parameters was validated for the scoring of apoptotic cell death in CGNs.

Results

In Caspase‐3 and Caspase‐9 transfected CGNs, cell death was scored both in transfectants and nontransfected culture‐mates. The cell death phenotype was found to be independent of transfection efficiency. LSC scoring of Caspase‐9 transfectants was compared with visual scoring following Hoechst 33342 staining, yielding results that were similar qualitatively, but not quantitatively, likely owing to the greater sensitivity to green fluorescence of laser scanning compared to human vision.

Conclusion

LSC scoring of transiently transfected CGNs offers a rapid and reliable means of characterizing proapoptotic gene effects. © 2006 International Society for Analytical Cytology
Comparison of fluorescein and phycoerythrin conjugates for quantifying CD20 expression on normal and leukemic B‐cells
Authors: Wang Lili , Abbasi Fatima , Gaigalas Adolfas K. , Vogt Robert F. , Marti Gerald E.
Published: September 2006

Background

Numerous methods for quantitative fluorescence calibration (QFC) have been developed to quantify receptor expression on lymphocytes as potential disease biomarkers. CD20 expression in B‐cell chronic lymphocytic leukemia (B‐CLL) is one of the best examples of such a biomarker, but results from the use of different QFC methods vary considerably.

Methods

We measured CD20 expression on normal and B‐CLL B‐cells, using FITC and PE conjugates from the same monoclonal antibody (Mab). As a biological control and calibrator, we also measured CD4 expression on T‐cells with FITC and PE Mab. Calibration curves were constructed using the CLSI (formerly NCCLS) consensus guidelines for QFC. Calibration with QuantiBRITE™ PE‐labeled microspheres and the use of unimolar PE conjugates provided direct measurement of antibody bound per cell (ABC) for CD4 and CD20. Calibration for FITC conjugates was based on molecules of equivalent soluble fluorochrome (MESF), as determined by NIST RM 8640 microsphere standards. These MESF values were then converted to ABC, using the CD4 T‐cell as a biologic calibrator, to normalize FITC and PE results for CD20 expression.

Results

On normal B cells, the mean ABC value for unimolar CD20‐PE conjugate was 143,500 (CV ± 19.1%). The mean ABC value for B‐CLL B‐cells stained with the same conjugate was 21,700 (CV ± 42.0%). Using the CD4 T‐cell as a biologic calibrator for FITC conjugate, the mean ABC value for CD20‐FITC on normal B‐cells was 199,300. CD20‐FITC staining on B‐CLL cells was generally too weak for accurate quantification. On normal T‐cells, the mean ABC value for CD4 unimolar PE conjugate was (36,800 ± 10.4)%, and it did not differ significantly in CLL samples.

Conclusion

The expression of CD20 on normal and B‐CLL lymphocytes can be quantified in ABC units using unimolar CD20‐PE conjugates. In addition, CD4 expression on T‐cells can be used as a biological calibrator to quantify CD20‐FITC ABC, with reasonable agreement between the two conjugates with different fluorochromes. Issues regarding the accuracy of MESF microsphere calibrators and effective F/P ratios for FITC conjugates will require additional laboratory studies. © 2006 International Society for Analytical Cytology
Preparation and Reductive Decomposition of 2‐Iodoxybenzenesulfonic Acid. X‐ray Crystal Structure of 1‐Hydroxy‐1H‐1,2,3‐benziodoxathiole 3,3‐Dioxide
Authors: Koposov Alexey Y. , Litvinov Dmitry N. , Zhdankin Viktor V. , Ferguson Michael J. , McDonald Robert , Tykwinski Rik R.
Published: September 2006

2‐Iodoxybenzenesulfonic acid (in a cyclic tautomeric form of 1‐hydroxy‐1H‐1,2,3‐benziodoxathiole 1,3,3‐trioxide), a thia‐analog of 2‐iodoxybenzoic acid (IBX) and a potentially important oxidizing reagent, was prepared by two different pathways: direct oxidation of 2‐iodobenzenesulfonic acid and hydrolysis of the methyl ester of 2‐iodylbenzenesulfonic acid. The resulting l‐hydroxy‐1H‐1,2,3‐benziodoxathiole 1,3,3‐trioxide was found to be thermally unstable and highly reactive towards organic solvents. The structure of its reductive decomposition product, l‐hydroxy‐1H‐1,2,3‐benziodoxathiole 3,3‐dioxide (the cyclic tautomeric form of 2‐iodosylbenzenesulfonic acid), was established by single‐crystal X‐ray diffraction.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Synthesis and Absolute Configuration of (+)‐Pseudodeflectusin: Structural Revision of Aspergione B
Authors: Saito Fumiyo , Kuramochi Kouji , Nakazaki Atsuo , Mizushina Yoshiyuki , Sugawara Fumio , Kobayashi Susumu
Published: September 2006

We report herein the total synthesis and determination of the absolute configuration of (+)‐pseudodeflectusin. The total synthesis of (+)‐pseudodeflectusin starting from o‐anisic aid was achieved in 11 total steps with an overall yield of 2.0 %. The 1H‐ and 13C NMR spectroscopic data of our synthetic pseudodeflectusin was identical to that of the natural compound. The absolute configuration of (+)‐pseudodeflectusin was determined by chiral HPLC and X‐ray crystallographic analyses. We also synthesized the proposed structure of aspergione B, whose 1H‐ and 13C NMR spectroscopic data is identical to that of pseudodeflectusin. The 1H‐ and 13C NMR spectra of our synthetic aspergione B were different from those of the natural compound reported by Proksch et al. Our results confirm that aspergione B and pseudodeflectusin are, in fact, the same compound.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Seasonal variations in the spatial‐temporal dependence of total column ozone
Authors: Stein Michael L.
Published: September 2006

The Total Ozone Mapping Spectrometer (TOMS) is a satellite‐based instrument that measures total column ozone on a daily basis over a fairly dense spatial grid with near global coverage. Statistical models for the spatial‐temporal variations in total column ozone provide insights into ozone dynamics, are valuable for obtaining inferences on long‐term trends in ozone levels, and can be used to predict ozone levels at unobserved points in space‐time. However, developing such a model is complicated by the seasonally varying nature of the space‐time dependence and the partial confounding of spatial and temporal variation caused by the sun‐synchronous orbit of the satellite. This work considers methods for describing, modeling and estimating the seasonal patterns in the dependence structure for measurements at a single latitude. Applying one of these models to the synoptic prediction of total column ozone at a latitude shows that there is at least the potential for substantially improved predictions by exploiting the high spatial density of observations TOMS provides. Copyright © 2006 John Wiley & Sons, Ltd.
Combining sampling and model weights in agriculture small area estimation
Authors: Militino A. F. , Ugarte M. D. , Goicoa T.
Published: September 2006

This paper is focussed on agriculture small area models for predicting minor crops. In the application considered here, the study domain is often poor in the crop of interest leading to irregular and sparsely distributed plots, usually smaller than the segments used in the sampling design. Hence, the variability among the sampled units becomes large in those areas with a high number of segments. To date, models including weights to account for heteroscedasticity, as well as models considering sampling weights to achieve design‐consistency have been proposed to derive estimators of small area means or totals. In this work, we discuss extensions of these models and the convenience of using both types of weighting. The models performance is illustrated for predicting the total area occupied by olive trees in a region of Navarra, Spain. Copyright © 2006 John Wiley & Sons, Ltd.