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Several Authors (several + author)
Selected AbstractsNaturalization and invasion of alien plants: concepts and definitionsDIVERSITY AND DISTRIBUTIONS, Issue 2 2000David M. Richardson Abstract., Much confusion exists in the English-language literature on plant invasions concerning the terms ,naturalized' and ,invasive' and their associated concepts. Several authors have used these terms in proposing schemes for conceptualizing the sequence of events from introduction to invasion, but often imprecisely, erroneously or in contradictory ways. This greatly complicates the formulation of robust generalizations in invasion ecology. Based on an extensive and critical survey of the literature we defined a minimum set of key terms related to a graphic scheme which conceptualizes the naturalization/invasion process. Introduction means that the plant (or its propagule) has been transported by humans across a major geographical barrier. Naturalization starts when abiotic and biotic barriers to survival are surmounted and when various barriers to regular reproduction are overcome. Invasion further requires that introduced plants produce reproductive offspring in areas distant from sites of introduction (approximate scales: > 100 m over < 50 years for taxa spreading by seeds and other propagules; > 6 m/3 years for taxa spreading by roots, rhizomes, stolons or creeping stems). Taxa that can cope with the abiotic environment and biota in the general area may invade disturbed, seminatural communities. Invasion of successionally mature, undisturbed communities usually requires that the alien taxon overcomes a different category of barriers. We propose that the term ,invasive' should be used without any inference to environmental or economic impact. Terms like ,pests' and ,weeds' are suitable labels for the 50,80% of invaders that have harmful effects. About 10% of invasive plants that change the character, condition, form, or nature of ecosystems over substantial areas may be termed ,transformers'. [source] Prediction of the behaviour of landslide dams using a geomorphological dimensionless indexEARTH SURFACE PROCESSES AND LANDFORMS, Issue 1 2003L. Ermini Abstract Landslide dams are a common phenomenon. They form when a landslide reaches the bottom of a river valley causing a blockage. The first effect of such a dam is the infilling of a lake that inundates the areas upstream, while the possibility of a sudden dam collapse, with a rapid release of the impounded waters, poses a higher flood risk to the downstream areas. The results of the main inventories carried out to date on landslide dams, have been examined to determine criteria for forecasting landslide dam evolution with particular emphasis on the assessment of dam stability. Not all landslides result in the blockage of a river channel. This only occurs with ones that can move a large amount of material with moderate or high-velocities. In most cases, these landslides are triggered by rainfall events or high magnitude earthquakes. A relationship also exists between the volume of the displaced material and the landslide dam stability. Several authors have proposed that landslide dam behaviour can be forecast by defining various geomorphological indexes, that result from the combination of variables identifying both the dam and the dammed river channel. Further developments of this geomorphological approach are presented in this paper by the definition of a dimensionless blockage index. Starting with an analysis of 84 episodes selected worldwide, it proved to be a useful tool for making accurate predictions concerning the fate of a landslide dam. Copyright © 2002 John Wiley & Sons, Ltd. [source] Inducing safer oblique trees without costsEXPERT SYSTEMS, Issue 4 2005Sunil Vadera Abstract: Decision tree induction has been widely studied and applied. In safety applications, such as determining whether a chemical process is safe or whether a person has a medical condition, the cost of misclassification in one of the classes is significantly higher than in the other class. Several authors have tackled this problem by developing cost-sensitive decision tree learning algorithms or have suggested ways of changing the distribution of training examples to bias the decision tree learning process so as to take account of costs. A prerequisite for applying such algorithms is the availability of costs of misclassification. Although this may be possible for some applications, obtaining reasonable estimates of costs of misclassification is not easy in the area of safety. This paper presents a new algorithm for applications where the cost of misclassifications cannot be quantified, although the cost of misclassification in one class is known to be significantly higher than in another class. The algorithm utilizes linear discriminant analysis to identify oblique relationships between continuous attributes and then carries out an appropriate modification to ensure that the resulting tree errs on the side of safety. The algorithm is evaluated with respect to one of the best known cost-sensitive algorithms (ICET), a well-known oblique decision tree algorithm (OC1) and an algorithm that utilizes robust linear programming. [source] Exploring the "two-hit hypothesis" in NF2: Tests of two-hit and three-hit models of vestibular schwannoma developmentGENETIC EPIDEMIOLOGY, Issue 4 2003Ryan Woods Abstract Neurofibromatosis 2 (NF2) is a genetic disease that occurs in approximately 1 in 40,000 live births. Almost all affected individuals develop bilateral tumors of Schwann cells that surround the vestibular nerves; these tumors are known as vestibular schwannomas (VS). Evidence from molecular genetic studies suggests that at least two mutations are involved in formation of VS in patients with NF2. Several authors proposed probabilistic models for this process in other tumors, and showed that such models are consistent with incidence data. We evaluated two different probabilistic models for a "2-hit" hypothesis for VS development in NF2 patients, and we present results from fitting these models to incidence data. Molecular evidence does not exclude the possibility that additional hits are necessary for the development of VS, and we also assessed a "3-hit" model for tumor formation. The "3-hit" model fits the data marginally better than one of the "2-hit" models and much better than the other "2-hit" model. Our findings suggest that more than two mutations may be necessary for VS development in NF2 patients. Genet Epidemiol 24:265,272, 2003. © 2003 Wiley-Liss, Inc. [source] Clinical curiosity: Cribriform-morular variant of papillary thyroid carcinoma,HEAD & NECK: JOURNAL FOR THE SCIENCES & SPECIALTIES OF THE HEAD AND NECK, Issue 5 2006Kimberly M. Dalal MD Abstract Background. There is an increasing awareness of the association of papillary thyroid carcinoma and familial adenomatous polyposis (FAP). Although the incidence is rare, most tend to occur in women. Several authors have described a distinctive histologic variant of papillary thyroid carcinoma, the cribriform-morular variant, which is associated with FAP but also may be encountered in patients with non-FAP. This diagnosis may precede the symptoms of colorectal polyposis. Methods. A healthy 36-year-old woman was seen with a left thyroid nodule, and a 34-year-old woman with FAP was seen with a right thyroid nodule; both masses were suspicious for papillary thyroid carcinoma. Both patients underwent total thyroidectomy. Results. Pathologic examination of both specimens revealed papillary thyroid carcinoma, cribriform-morular variant. The first patient subsequently underwent colonoscopy, which was negative for polyposis. Conclusions. Patients diagnosed with the cribriform-morular variant of papillary thyroid cancer should be screened for the presence of FAP. © 2006 Wiley Periodicals, Inc. Head Neck28: 471,476, 2006 [source] Role of hepatitis C virus proteins (C, NS3, NS5A) in hepatic oncogenesisHEPATOLOGY RESEARCH, Issue 1 2008Aldona Kasprzak In recent years, the effects of hepatitis C virus (HCV) proteins on hepatocarcinogenesis have undergone intense investigations. The potentially oncogenic proteins include at least three HCV proteins: core (C) protein, NS3, and NS5A. Several authors indicated relationships between subcellular localization, concentration, a specific molecular form of the proteins (full length, truncated, phosphorylated), the presence of specific domains (the nuclear localization signal homologous to e.g. Bcl-2) and their effects on the mechanisms linked to oncogenesis. The involvement of all the proteins has been described as being in control of the cell cycle, through interactions with key proteins of the process (p53, p21, cyclins, proliferating cell nuclear antigen), transcription factors, proto-oncogenes, growth factors/cytokines and their receptors, and proteins linked to the apoptotic process. Untilnow, the involvement of the core protein of HCV in liver carcinogenesis is the most recognized. One of the most common proteins affected by HCV proteins is the p53 tumor-suppressor protein. The p21/WAF1 gene is a major target of p53, and the effect of HCV proteins on the gene is frequently considered in parallel. The results of studies on the effects of HCV proteins on the apoptotic process are controversial. This work summarizes the information collected thus far in the field of HCV molecular virology and principal intracellular signaling pathways in which HCV oncogenic proteins are involved. [source] Infant-holding biases in mothers and affective symptoms during pregnancy and after deliveryINFANT AND CHILD DEVELOPMENT, Issue 2 2009Jacques Vauclair Abstract Several authors have reported that participants have a leftward bias when holding a newborn or young infant. Our study of mothers met before and after their infant's birth sought to ascertain whether particular combinations of affective symptoms (depression, anxiety) and holding positions (horizontal versus vertical) were related to holding-side biases. Our results showed that (a) mothers displayed a significant leftward (71%) holding bias, (b) mothers with affective symptoms held their newborn on the right side and more frequently in the vertical position, and (c) hemispheric specialization for perceiving visual emotions had no significant effect on the holding-side biases of new mothers. These results suggest that maternal affective symptoms have a dominant effect on the determination of holding-side preferences, when associated with a particular holding position. Copyright © 2008 John Wiley & Sons, Ltd. [source] Cloning, expression and partial characterization of a Haemaphysalis longicornis and a Rhipicephalus appendiculatus glutathione S -transferaseINSECT MOLECULAR BIOLOGY, Issue 3 2004I. Da Silva Vaz Jnr Abstract The ticks Haemaphysalis longicornis and Rhipicephalus appendiculatus are important parasites worldwide. The current method for control of cattle ticks involves the use of chemicals. Nevertheless, parasite resistance is an ever increasing global problem. Glutathione S -transferases (GSTs) play a central role in detoxication of xenobiotic and endogenous compounds. Several authors have noted that an increase in GST activity is associated with resistance to insecticides and acaricides. In the present study, we report the cloning and expression of GST cDNAs from H. longicornis and R. appendiculatus. In addition, we determine the effect of three acaricides (ethion, deltamethrin and diazinon) on the enzymatic activity of rGSTs. [source] Recombinant DRB sequences produced by mismatch repair of heteroduplexes during cloning in Escherichia coliINTERNATIONAL JOURNAL OF IMMUNOGENETICS, Issue 6 2002M. Longeri Summary Recombinant chimeric sequences originating from a mixture of the sequences of two different alleles are frequently found after amplification and cloning in Escherichia coli of exon 2 of the major histocompatibility complex (MHC) DRB genes. Several authors have suggested that the recombinant molecules result from in vitro recombination during PCR; nevertheless, a clear experimental demonstration of this hypothesis is lacking. In order to understand the mechanism producing the chimeric sequences, we set up a simple experiment based on the different restriction patterns of parental and recombinant sequences. Our data demonstrate that in the analysed case most of the recombinant variants were not produced by in vitro recombination during PCR, but were the result of the mismatch repair of heteroduplex molecules during cloning in E. coli. The high mutation rate in the ,-helix region of DRB expressed genes, both after cloning in E. coli and after the germ-line differentiation process in vertebrates, suggests that the observed mutations are the result of similar gene conversion processes, probably favoured by chi-dependent microrecombination events. [source] Local atomic structure in tetragonal pure ZrO2 nanopowdersJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 2 2010Leandro M. Acuña The local atomic structures around the Zr atom of pure (undoped) ZrO2 nanopowders with different average crystallite sizes, ranging from 7 to 40,nm, have been investigated. The nanopowders were synthesized by different wet-chemical routes, but all exhibit the high-temperature tetragonal phase stabilized at room temperature, as established by synchrotron radiation X-ray diffraction. The extended X-ray absorption fine structure (EXAFS) technique was applied to analyze the local structure around the Zr atoms. Several authors have studied this system using the EXAFS technique without obtaining a good agreement between crystallographic and EXAFS data. In this work, it is shown that the local structure of ZrO2 nanopowders can be described by a model consisting of two oxygen subshells (4 + 4 atoms) with different Zr,O distances, in agreement with those independently determined by X-ray diffraction. However, the EXAFS study shows that the second oxygen subshell exhibits a Debye,Waller (DW) parameter much higher than that of the first oxygen subshell, a result that cannot be explained by the crystallographic model accepted for the tetragonal phase of zirconia-based materials. However, as proposed by other authors, the difference in the DW parameters between the two oxygen subshells around the Zr atoms can be explained by the existence of oxygen displacements perpendicular to the z direction; these mainly affect the second oxygen subshell because of the directional character of the EXAFS DW parameter, in contradiction to the crystallographic value. It is also established that this model is similar to another model having three oxygen subshells, with a 4 + 2 + 2 distribution of atoms, with only one DW parameter for all oxygen subshells. Both models are in good agreement with the crystal structure determined by X-ray diffraction experiments. [source] The uptake of applied ecologyJOURNAL OF APPLIED ECOLOGY, Issue 1 2002S. J. Ormerod Summary 1We asked 229 authors who have published recently in the Journal of Applied Ecology (1999,2001) whether their papers made management or policy recommendations and whether they had evidence of consequent uptake. 2A total of 108 respondents working in the UK (34%), Europe (30%), the Americas (12%), Australasia (11%), Asia (7%) and Africa (6%) reported on 110 papers. They represented agro-ecosystems (35%), temperate forests or woodlands (16%), savanna, grass or arid lands (11%), rivers or wetlands (10%), estuaries or marine systems (7%) and tropical forests (5%). The major organisms were invertebrates (27%), birds (24%), mammals (21%) and higher plants (21%). Topics apparently under-represented in recent coverage include ecosystem science, urban areas, soils, mountain systems, fish, amphibians and lower organisms such as algae. 3Almost all papers (99%) carried recommendations and for 57% there was evidence of uptake in the broad categories of ,environmental management or models', ,information, training and education' and ,monitoring and assessment'. Most uptake involved large geographical scales through habitat or species management plans (32% of cases), effects on reserve design or designation (6%), and effects on agri-environmental policy (5%). The development of further research (11%), the communication of methods to other ecologists (9%), the dissemination of recommendations to practitioners or agencies (7%), and uptake in training or education (5%) were important uses of information. 4Prestige from publication in the Journal of Applied Ecology aided several authors in convincing end-users of research value. User involvement in research as participants or funders was widespread (> 42% of papers), a fact which almost certainly promotes uptake along with the parallel dissemination of management messages. We view applied issues as an important interface between end-users and ecologists of value to ,both' communities but suggest that improved communication will further benefit the sponsorship and application of ecological science. 5The major reason offered for lack of uptake was that it was still too soon after publication (21% of respondents). Costs, difficulty of implementation, the scale of the problem, and ,challenges to existing thinking' each figured in more than one response. 6For some respondents, papers were led by curiosity rather than the need for direct application. Several authors published in the Journal to share ideas internationally, or said that recommendations were general, conceptual or long-term rather than specific. The editors of the Journal of Applied Ecology recognize the seminal importance of contributions that affect policy incrementally and conceptually as much as those with specific application. 7These data provide evidence that ecological science is aiding environmental management and policy across a wide range of regions, ecosystems and types of organisms; rather than merely detecting problems, applied ecology is offering solutions both directly and more diffusely through conceptual advance. We invite the user community to offer their own perspectives about the value of research-led publications such as this Journal, about how links between researchers and users might be strengthened, and about how the uptake of applied ecology might be further advanced. [source] A weak degeneracy revealing decomposition for the CANDECOMP/PARAFAC modelJOURNAL OF CHEMOMETRICS, Issue 2 2010Roberto Rocci Abstract The CANDECOMP/PARAFAC (CP) model is a well known and frequently used tool for extracting substantial information from a three-way data array. It has several useful characteristics and usually gives meaningful insights about the underlying structure of the data. However, in some cases it has a ,strange' behaviour suffering from the so-called ,degenerate solutions', i.e. solutions where the components show a diverging pattern and are meaningless. Several authors have investigated the causes of degeneracy concluding that the phenomenon is due to a lack of minimum of the loss function. In this paper, we study the degeneracy of CP limiting our attention to the two-component case. The study is done by introducing a canonical form, called 2DR, which is ,weakly degeneracy revealing'. On the ground of this framework, degeneracy is studied along with some of the remedies proposed in the literature by using a Tucker3 model having a core in the 2DR form. The analysis gives new insights about the behaviour of the CP model and suggests new ideas on how to deal with degeneracy. Copyright © 2010 John Wiley & Sons, Ltd. [source] Types of lymphoscintigraphy and indications for lymphaticovenous anastomosisMICROSURGERY, Issue 6 2010Jiro Maegawa M.D. Several authors have reported the usefulness and benefits of lymphoscintigraphy. However, it is insufficient to indicate microvascular treatment based on lymphedema. Here, we present the relationships between lymphoscintigraphic types and indications for lymphatic microsurgery. Preoperative lymphoscintigraphy was performed in 142 limbs with secondary lymphedema of the lower extremity. The images obtained were classified into five types. Type I: Visible inguinal lymph nodes, lymphatics along the saphenous vein and/or collateral lymphatics. Type II: Dermal backflow in the thigh and stasis of an isotopic material in the lymphatics. Type III: Dermal backflow in the thigh and leg. Type IV: Dermal backflow in the leg. Type V: Radiolabeled colloid remaining in the foot. Lymphaticovenous anastomosis was performed in 35 limbs. The average number of anastomoses per limb was 3.3 in type II, 4.4 in type III, 3.6 in type IV, and 3 in type V. The highest number of anastomosis was performed in type III. In conclusion, type III is suggested to be the best indication for anastomosis compared with types IV and V. © 2010 Wiley-Liss, Inc. Microsurgery 30:437,442, 2010. [source] Internal algorithm variability and among-algorithm discordance in statistical haplotype reconstructionMOLECULAR ECOLOGY, Issue 8 2009ZU-SHI HUANG The potential effectiveness of statistical haplotype inference makes it an area of active exploration over the last decade. There are several complications of statistical inference, including: the same algorithm can produce different solutions for the same data set, which reflects the internal algorithm variability; different algorithms can give different solutions for the same data set, reflecting the discordance among algorithms; and the algorithms per se are unable to evaluate the reliability of the solutions even if they are unique, this being a general limitation of all inference methods. With the aim of increasing the confidence of statistical inference results, consensus strategy appears to be an effective means to deal with these problems. Several authors have explored this with different emphases. Here we discuss two recent studies examining the internal algorithm variability and among-algorithm discordance, respectively, and evaluate the different outcomes of these analyses, in light of Orzack (2009) comment. Until other, better methods are developed, a combination of these two approaches should provide a practical way to increase the confidence of statistical haplotyping results. [source] Stellar velocity dispersion in narrow-line Seyfert 1 galaxiesMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 2 2005V. Botte ABSTRACT Several authors have recently explored, for narrow-line Seyfert 1 galaxies (NLS1s), the relationship between black hole mass (MBH) and stellar velocity dispersion (,*). Their results are more or less in agreement and seem to indicate that NLS1s fill the region below the fit obtained by Tremaine et al., showing a range of ,* similar to that of Seyfert 1 galaxies, and a lower MBH. Until now, the [O iii] width has been used in place of the stellar velocity dispersion, but some indications have begun to arise against the effectiveness of the gaseous kinematics in representing the bulge potential, at least in NLS1s. Bian & Zhao have stressed the urgency of producing true ,* measurements. Here, we present new stellar velocity dispersions obtained through direct measurements of the Ca ii absorption triplet (,8550 Å) in the nuclei of eight NLS1 galaxies. The resulting ,* values and a comparison with ,[O III] confirm our suspicion that [O iii] typically overestimates the stellar velocity dispersion. We demonstrate that NLS1s follow the MBH,,* relation as Seyfert 1, quasars and non-active galaxies. [source] Chemosensitivity of the human gastrointestinal tract in health and in diseaseNEUROGASTROENTEROLOGY & MOTILITY, Issue 4 2007J. Tack Abstract, Although visceral sensitivity in man comprises chemosensitivity, thermosensitivity and mechanosensitivity, only the latter has been intensively studied. Studies in health have aimed at characterising the type of mechanoreceptors involved in visceral mechanosensitivity,. Several authors have studied the prevalence and relevance to the symptom pattern of hypersensitivity to visceral balloon distention in patients with functional gastrointestinal disorders. Chemosensitivity of the gastrointestinal tract in man has received much less attention. In this issue of Neurogastroenterology and Motility, intraluminal application of capsaicin is described as a tool to study chemosensitivity of the proximal gastrointestinal tract. The authors report how activation of chemosensitive pathways induces symptoms that differ from those induced by activation of mechanosensitive pathways, and propose to use capsaicin as a tool to study the prevalence and role of hypersensitivity to visceral chemosensitivity in patients with functional gastrointestinal disorders. Our current knowledge of visceral chemosensitivity of the human gastrointestinal tract in health and in disease is reviewed, with a specific focus on the interaction between mechano- and chemosensitive pathways. [source] Inclusive heritability: combining genetic and non-genetic information to study animal behavior and cultureOIKOS, Issue 2 2010Étienne Danchin Phenotypic variance results from variation in biological information possessed by individuals. Quantitative geneticists often strive to partition out all environmental variance to measure heritability. Behavioral biologists and ecologists however, require methods to integrate genetic and environmental components of inherited phenotypic variance in order to estimate the evolutionary potential of traits, which encompasses any form of information that is inherited. To help develop this integration, we build on the tools of quantitative genetics and offer the concept of ,inclusive heritability' which identifies and unifies the various mechanisms of information transmission across generations. A controversial component of non-genetic information is animal culture, which is the part of phenotypic variance inherited through social learning. Culture has the unique property of being transmitted horizontally and obliquely, as well as vertically. Accounting for cultural variation would allow us to examine a broader range of evolutionary mechanisms. Culture may, for instance, produce behavioral isolating mechanisms leading to speciation. To advance the study of animal culture, we offer a definition of culture that is rooted in quantitative genetics. We also offer four testable criteria to determine whether a trait is culturally inherited. These criteria may constitute a conceptual tool to study animal culture. We briefly discuss methods to partition out cultural variance. Several authors have recently called for ,modernizing the modern synthesis' by including non-genetic factors such as epigenetics and phenotypic plasticity in order to more fully explain phenotypic evolution. Here, we further propose to broaden the concept of inheritance by incorporating the cultural component of behavior. Applying the concept of inclusive heritability may advance the integration of multiple forms of inheritance into the study of evolution. [source] Matching and ideal free distributionsOIKOS, Issue 7 2008Alasdair I. Houston Ideal free distributions characterise how a group of animals should be distributed between sources of food. In a simple case, the ratio of the number of animals matches the ratio of input rates, a result known as input matching. The matching law characterises how an animal should allocate responses to sources of food. If matching holds then the ratio of behaviour allocated to the sources matches the ratio of rewards obtained. Several authors have drawn attention to the analogy between input matching and the matching law. I present a critical review of this topic, and go on to investigate the claim that the distribution of animals should be analyzed in the same way that the generalized matching law is analyzed. This involves assuming that the relationship between the ratio of animals and the ratio of resources obeys a power law with two parameters, one corresponding to bias and the other to sensitivity. On this view, a plot of the log of the ratio of animals against the log of the ratio of input rates will be a straight line and its intercept and slope will provide estimates of bias and sensitivity. I show that this approach can give a good fit even when the underlying model does not result in a power law. A consequence is that the parameters estimated cannot be interpreted as bias and sensitivity. I conclude that there are no compelling reasons for analyzing the distribution of animals using log-log plots, and the method has the disadvantage of encouraging the mistaken view that deviations from input matching follow a power law. [source] ON THE PATH OF AN OIL PIGOVIAN TAX,THE MANCHESTER SCHOOL, Issue 5 2009ANTOINE BELGODERE, Article first published online: 14 JUL 200 This paper studies optimal climate policy in the presence of oil rents. Several authors have found that, according to Hotelling's rule, in the long run, the optimal ad valorem tax must decrease. However, if the pollution is a stock and if environmental concerns impose stopping the resource extraction before its exhaustion, we show that an ad valorem tax defined over the rent cannot decentralize the optimum. In this case, an increasing per-unit tax can decentralize the optimum. Such a tax implies the disappearance of the Hotelling rent. Thus, the extraction problem reduces to a pollution-control problem. [source] The role of impulsivity in actual and problematic use of the mobile phoneAPPLIED COGNITIVE PSYCHOLOGY, Issue 9 2008Joël Billieux Several authors have investigated the risks arising from the growth in mobile phone use (e.g. debts incurred by young people). The aims of the present study are (1) to validate a new questionnaire assessing problematic mobile phone use: the Problematic Mobile Phone Use Questionnaire (PMPUQ), and (2) to investigate the relationships between the PMPUQ and the multi-faceted construct of impulsivity. With these aims, 339 subjects were screened using the PMPUQ and the UPPS Impulsive Behaviour Scale (UPPS) which assesses four distinct components associated with impulsive behaviours (urgency, lack of premeditation, lack of perseverance and sensation seeking). The results showed that the PMPUQ has an acceptable fit and assesses four different dimensions of problematic mobile phone use (prohibited use, dangerous use, dependence, financial problems). While each facet of impulsivity played a specific role in mobile phones use, urgency appeared to be the strongest predictor of problematic use. Copyright © 2008 John Wiley & Sons, Ltd. [source] A NOTE ON SAMPLING DESIGNS FOR RANDOM PROCESSES WITH NO QUADRATIC MEAN DERIVATIVEAUSTRALIAN & NEW ZEALAND JOURNAL OF STATISTICS, Issue 3 2006Bhramar Mukherjee Summary Several authors have previously discussed the problem of obtaining asymptotically optimal design sequences for estimating the path of a stochastic process using intricate analytical techniques. In this note, an alternative treatment is provided for obtaining asymptotically optimal sampling designs for estimating the path of a second order stochastic process with known covariance function. A simple estimator is proposed which is asymptotically equivalent to the full-fledged best linear unbiased estimator and the entire asymptotics are carried out through studying this estimator. The current approach lends an intuitive statistical perspective to the entire estimation problem. [source] Towards a Unifying Model of Systems of Law, Corporate Financing, Accounting and Corporate GovernanceAUSTRALIAN ACCOUNTING REVIEW, Issue 20 2000CHRISTOPHER NOBES Several authors have observed a relationship between a country's type of legal system and its style of financial reporting. Generally, the causality is presumed to be from legal system to accounting system. However, one model of accounting differences suggests that the type of accounting is an influence on the regulatory system rather than vice versa. This helps to explain why the Netherlands has Roman law but approximately Anglo-Saxon accounting. It also allows for the extensive use by European companies of US or international rules. This paper expands on these themes, and extends the model to include corporate governance. [source] Predictive validity of the Psychopathy Checklist: Youth Version for general and violent recidivismBEHAVIORAL SCIENCES & THE LAW, Issue 1 2004Raymond R. Corrado Ph.D. Several authors have expressed concern regarding the use of youth psychopathy assessments in determinations of risk for general and violent offending. The Psychopathy Checklist: Youth Version (PCL:YV) was completed with 182 male adolescent offenders in this prospective study (average 14.5 month follow-up) of general and violent recidivism. Both a two-factor and three-factor model of the PCL:YV significantly predicted general and violent recidivism at a predictive accuracy ranging from 68 to 63%. However, regression analyses indicated these associations were explained primarily by behavioral psychopathic symptoms, rather than interpersonal or affective traits. Implications for the use of psychopathy assessments for risk during adolescence are discussed. Copyright © 2004 John Wiley & Sons, Ltd. [source] Metabolic effects and the methylenetetrahydrofolate reductase (MTHFR) polymorphism associated with neural tube defects in southern Brazil,BIRTH DEFECTS RESEARCH, Issue 7 2004Têmis Maria Félix Abstract BACKGROUND The importance of metabolic factors in neural tube defects (NTDs) has been the focus of many investigations. Several authors have suggested that abnormalities in homocysteine metabolism, such as hyperhomocysteinemia, folate deficiency, and low vitamin B12, may be responsible for these malformations and that both nutritional factors and genetic abnormalities are associated with them. METHODS We conducted a case-control study to investigate the influence of biochemical and genetic factors in NTDs in infants in southern Brazil. Levels of folate, vitamin B12, total homocysteine (t-Hcy) and the 677C>T and 1298A>C polymorphisms of the MTHFR gene were analyzed in 41 NTD child,mother pairs and 44 normal child,mother control pairs. RESULTS Subjects in the case group had a higher mean blood folate level than those in the control group. The level of vitamin B12 was lower in mothers in the NTD group than in control mothers (p = 0.004). The level of t-Hcy was not different in the two groups, but t-Hcy and vitamin B12 were correlated (p = 0.002). There was no difference in the genotype distribution for 677C>T and 1298A>C polymorphisms of MTHFR in the case and control pairs. The level of t-Hcy was correlated with 677TT. CONCLUSIONS Despite the small sample in this study, we suggest that low vitamin B12 and, consequently, hyperhomocysteinemia are important risk factors for NTDs in our population. Birth Defects Research (Part A), 2004. © 2004 Wiley-Liss, Inc. [source] Ontogenesis of internal secretory cells in leaves of Lantana camara (Verbenaceae)BOTANICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 4 2005MARIA ZABELÊ DANTAS MOURA Internal secretory cells may be morphologically indistinguishable from their neighbours except for the presence of secreted material, or they may differ to such an extent that could be classified as secretory idioblasts. Several authors have reported the presence of glandular trichomes secreting essential oil in Verbenaceae, including Lantana. However, none have reported internal secretory cells. Anatomical and histochemical methods applied to Lantana camara leaves revealed the occurrence of internal secretory cells whose ontogenesis and chemical nature are described in this paper. According to leaf developmental analysis, L. camara secretory cells originated from the ground meristem, started to differentiate in the third node leaves, and were actively secreting in the fourth node leaves. The content of the secretory cells was of a lipidic nature, and a terpenoid essence of their secretion was also identified. Based upon differences in size and shape from neighbouring cells and on detection of nonvolatile terpenes, they were confirmed as true internal secretory idioblasts. © 2005 The Linnean Society of London, Botanical Journal of the Linnean Society, 2005, 148, 427,431. [source] Should adjuvant radiotherapy be recommended following resection of regional lymph node metastases of malignant melanomas?BRITISH JOURNAL OF DERMATOLOGY, Issue 1 2001D. Fuhrmann Background ,Several authors have recommended adjuvant radiotherapy following resection of regional lymph node metastases in cutaneous malignant melanoma. There is, however, little evidence from controlled trials that patients benefit from this treatment. Objectives ,To evaluate the usefulness of adjuvant radiotherapy following resection of lymph node metastases in cutaneous malignant melanoma. Methods ,We performed a retrospective study comparing 58 patients who underwent radiotherapy following resection of regional lymph node metastases with 58 controls from another centre who exclusively underwent regional lymphadenectomy. Patients and their controls were matched with respect to the number of tumour-bearing lymph nodes (1 vs. >,1) and to gender, although the proportion of thick tumours was greater in the irradiation group. Results ,The overall survival curves were almost identical in the two groups. There were nine disease recurrences in the study group and 12 in the control group (not significant). Regional recurrences in the irradiated patients were usually accompanied by metastases at other sites. Conclusions ,The present study does not support the recommendation of adjuvant radiotherapy following resection of regional lymph node metastases in patients with malignant melanoma. [source] Progressive stroke in pontine infarctionACTA NEUROLOGICA SCANDINAVICA, Issue 4 2009V. Saia Objective,,, The pathogenesis of isolated pontine infarctions is still unclear, being attributed both to small or large vessel disease. The extension of infarcted tissue to the pons surface has been indicated as a possible marker of basilar branch atheromatous disease and some neuroimaging evidence confirms this finding. Methods,,, On the basis of Kim's et al., study, we performed a revision of the literature addressing this topic. Results,,, Several authors confirm an association between basilar artery branch disease and isolated pontine infarction; moreover, the enlargement of pontine lesion seems to be associated with neurological worsening. We therefore performed a brief analysis of possible mechanisms of progression. Conclusions,,, Prospective studies could be useful to evaluate predictors of neurological worsening in pontine stroke. Improvement of neuroimaging techniques is needed for a deeper comprehension of the etiopathogenesis of isolated pontine infarction. [source] 2324: Comparison of algorithms for oximetry in vivo and ex vivoACTA OPHTHALMOLOGICA, Issue 2010D DE BROUWERE Purpose Several authors have proposed a number of algorithms to extract the oxygen saturation in retinal blood vessels based on multispectral image analysis. We evaluated the outcomes of seven known algorithms based on hyperspectral retinal images. Methods Hyperspectral images are acquired using a fundus camera where a slit spectrograph is registered onto a retinal image. This combination compromises both accurate spatial and spectral information over the selected slit. Hyperspectral image analysis was used as input for the oximetry calculations described in the literature. We used a model eye to evaluate the different techniques in a controlled setup. Defibrinated horse blood was perfused through microtubules placed in front of a white (spectralon) background. Oxygen saturation was controlled by mixing different concentrations of sodium dithianate in the blood. Results Oxygen saturation was varied in five equidistant steps between 0 and 1. We correlated the outcomes to the metric of Harvey et al. [Biomed Optics 6631, 2007] Linear correlation with other algorithms resulted in r2 values between 0.881 and 0.985, however we observed a large discrepancy of the slope of each correlation line. The algorithms were also evaluated in images recorded in five healthy volunteers. In all techniques, veins could be separated from arteries by their reduces oxygen saturation, although values varied strongly between the different techniques. Conclusion Our findings confirm the working of a number of noninvasive retinal oximetry algorithms. Different readings can be can be attributed to an offset caused by an uncertainty of pigmentation and scattering parameters in the calibration procedure. [source] Role of transarterial chemoembolization for hepatocellular carcinoma before liver transplantation with special consideration of tumor necrosisCLINICAL TRANSPLANTATION, Issue 2009André Schaudt Abstract:, Several authors suggest that local ablative therapies, specifically transarterial chemoembolization (TACE), may control tumor progression of hepatocellular carcinoma (HCC) in patients who are on the waiting list for liver transplantation (orthotopic liver transplantation, OLT). There is still no evidence if TACE followed by OLT is able to prevent recurrence of tumor, to prolong survival rate of the patients on the waiting list, or to improve the survival after OLT. We report 27 patients with HCC who underwent OLT. From these patients, 15 were pre-treated with TACE alone or in combination with percutaneous ethanol injection (PEI) or laser-induced thermo therapy (LITT). Mean time on the waiting list was 214 d for treated patients and 133 d for untreated patients. Comparing pre-operative imaging and histopathological staging post-transplant, we found 13 patients with tumor progression out of which five were treated with TACE. In two of the TACE patients a decrease of lesions could be achieved. In a single patient, there was no evidence of any residual tumor. Only one patient displayed tumor progression prior to OLT despite undergoing TACE. Comparison of outcome in patients undergoing TACE or having no TACE was not statisitically significant (p = 0.5). In addition, our analysis showed that progression either in the total study population or in the TACE group alone is associated with a significant poorer outcome concerning overall survival (p = 0.02 and p = 0.02). [source] Computer programs for estimating substrate flux into steady-state biofilms from pseudoanalytical solutionsCOMPUTER APPLICATIONS IN ENGINEERING EDUCATION, Issue 1 2002Chetan T. Goudar Abstract Fixed-film processes employing microorganisms attached to an inert surface (biofilms) are widely used for biological treatment of municipal and industrial wastewater. For optimal design and analysis of these processes, mathematical models are necessary that describe the dynamics of contaminant transport within these biofilms and the associated contaminant utilization by the microorganisms. However, these governing equations that typically involve Fickian diffusion for contaminant transport and Monod kinetics for contaminant utilization are inherently nonlinear and have no closed form solutions except under special conditions. This can restrict their use in the classroom as cumbersome numerical techniques must be used for their solution. This problem is well documented in the literature and several authors have presented pseudoanalytical solutions that replace numerical solutions with algebraic equations. In the present study, we present pseudoanalytical solution-based computer programs for estimating substrate flux and biofilm thickness for a steady-state biofilm. Depending upon the intended end use, these programs can either partially or totally automate the solution process. In the partial automation mode, they can serve to enhance student understanding of important concepts related to steady-state biofilms, while complete automation can help bring more challenging and realistic problems associated with steady-state biofilms into the classroom. The programs have been tested on MATLAB version 5.0 and are available as freeware for educational purposes. © 2002 Wiley Periodicals, Inc. Comput Appl Eng Educ 10: 26,32, 2002; Published online in Wiley InterScience (www.interscience.wiley.com.); DOI 10.1002/cae.10017 [source] | ||||||||||||||||||||||||||||||||||||||||