289 research outputs found
A Trusting Public: How the Public Trust Doctrine Can Save the New York Forest Preserve
The public trust doctrine was instituted in England as a permanent limitation on the powers of the Crown. The well-established doctrine was brought to America and applied equally in the states even after the states seceded from England. The doctrine has since served as an indestructible check on the government. Article XIV of the New York State Constitution ensures protection of its wilderness in perpetuity, solidifying the forest preserve as part of the public trust. The paper traces the beginnings of the public trust doctrine and its eventual application Article XIV. The author contemplates the indestructibility of the Forest Preserve as she examines how Article XIV serves as a limitation on government in order to protect the forest preserve through the safeguards of the public trust
Mixtures of Regression Models for Time-Course Gene Expression Data: Evaluation of Initialization and Random Effects
Finite mixture models are routinely applied to time course microarray data.
Due to the complexity and size of this type of data the choice of good starting values plays
an important role. So far initialization strategies have only been investigated for data
from a mixture of multivariate normal distributions. In this work several initialization
procedures are evaluated for mixtures of regression models with and without random
effects in an extensive simulation study on different artificial datasets. Finally these
procedures are also applied to a real dataset from E. coli
Selection models with monotone weight functions in meta analysis
Publication bias, the fact that studies identified for inclusion in a meta
analysis do not represent all studies on the topic of interest, is commonly
recognized as a threat to the validity of the results of a meta analysis. One
way to explicitly model publication bias is via selection models or weighted
probability distributions. We adopt the nonparametric approach initially
introduced by Dear (1992) but impose that the weight function is monotonely
non-increasing as a function of the -value. Since in meta analysis one
typically only has few studies or "observations", regularization of the
estimation problem seems sensible. In addition, virtually all parametric weight
functions proposed so far in the literature are in fact decreasing. We discuss
how to estimate a decreasing weight function in the above model and illustrate
the new methodology on two well-known examples. The new approach potentially
offers more insight in the selection process than other methods and is more
flexible than parametric approaches. Some basic properties of the
log-likelihood function and computation of a -value quantifying the evidence
against the null hypothesis of a constant weight function are indicated. In
addition, we provide an approximate selection bias adjusted profile likelihood
confidence interval for the treatment effect. The corresponding software and
the datasets used to illustrate it are provided as the R package selectMeta.
This enables full reproducibility of the results in this paper.Comment: 15 pages, 2 figures. Some minor changes according to reviewer
comment
New consistency index based on inertial operating speed
The occurrence of road crashes depends on several factors, with design consistency (i.e., conformance of highway geometry to drivers' expectations) being one of the most important. A new consistency model for evaluating the performance of tangent-to-curve transitions on two-lane rural roads was developed. This model was based on the inertial consistency index (ICI) defined for each transition. The ICI was calculated at the beginning point of the curve as the difference between the average operating speed on the previous 1-km road segment (inertial operating speed) and the actual operating speed at this point. For the calibration of the ICI and its thresholds, 88 road segments, which included 1,686 tangent-to-curve transitions, were studied. The relationship between those results and the crash rate associated with each transition was analyzed. The results showed that the higher the ICI was, the higher the crash rate; thus, the probability of accidents increased. Similar results were obtained from the study of the relationship between the ICI and the weighted average crash rate of the corresponding group of transitions. A graphical and statistical analysis established that road consistency might be considered good when the ICI was lower than 10 km/h, poor when the ICI was higher than 20 km/h, and fair otherwise. A validation process that considered 20 road segments was performed. The ICI values obtained were highly correlated to the number of crashes that had occurred at the analyzed transitions. Thus, the ICI and its consistency thresholds resulted in a new approach for evaluation of consistency.The authors thank the Center for Studies and Experimentation of Public Works of the Spanish Ministry of Public Works, which partially subsidized the data collection, for obtaining the empirical operating speed profiles used in the validation process. The authors also thank the General Directorate of Public Works of the Infrastructure and Transportation Department of the Valencian government, the Valencian Province Council, and the General Directorate of Traffic of the Ministry of the Interior of the Government of Spain for their cooperation in data gathering.García García, A.; Llopis Castelló, D.; Camacho Torregrosa, FJ.; Pérez Zuriaga, AM. (2013). New consistency index based on inertial operating speed. Transportation Research Record. (2391):105-112. doi:10.3141/2391-10S1051122391Ng, J. C. ., & Sayed, T. (2004). Effect of geometric design consistency on road safety. Canadian Journal of Civil Engineering, 31(2), 218-227. doi:10.1139/l03-090Gibreel, G. M., Easa, S. M., Hassan, Y., & El-Dimeery, I. A. (1999). State of the Art of Highway Geometric Design Consistency. Journal of Transportation Engineering, 125(4), 305-313. doi:10.1061/(asce)0733-947x(1999)125:4(305)Hassan, Y. (2004). Highway Design Consistency: Refining the State of Knowledge and Practice. Transportation Research Record: Journal of the Transportation Research Board, 1881(1), 63-71. doi:10.3141/1881-08Polus, A., & Mattar-Habib, C. (2004). New Consistency Model for Rural Highways and Its Relationship to Safety. Journal of Transportation Engineering, 130(3), 286-293. doi:10.1061/(asce)0733-947x(2004)130:3(286)Cafiso, S., Di Graziano, A., Di Silvestro, G., La Cava, G., & Persaud, B. (2010). Development of comprehensive accident models for two-lane rural highways using exposure, geometry, consistency and context variables. Accident Analysis & Prevention, 42(4), 1072-1079. doi:10.1016/j.aap.2009.12.015Zuriaga, A. M. P., García, A. G., Torregrosa, F. J. C., & D’Attoma, P. (2010). Modeling Operating Speed and Deceleration on Two-Lane Rural Roads with Global Positioning System Data. Transportation Research Record: Journal of the Transportation Research Board, 2171(1), 11-20. doi:10.3141/2171-0
Transfermulch verringert Blattschäden durch den Kohlweißling im ökologischen Kohlanbau
In einem einjährigen Versuch wurden tote Mulche auf Kohlrabi ausgebracht und die Blattschäden durch Raupen von Pieris spp. untersucht. Erste Ergebnisse zeigen, dass die Mulche die Blattschäden durch die Raupen um mehr als 87 % reduzierten
Biostimulantien als Blattapplikation wirken auf Spross- und Wurzelmasse sowie Wurzelaktivität in Ackerbohnen (Vicia Faba)
Topfversuch wurde die Wirkung von Biostimulanzien auf die Wurzel- und Sprossparameter der Ackerbohne untersucht. Komposttee und sterilisierter Komposttee erhöhten die Trockensubstanz der Wurzel- und Sprossmasse signifikant. Lithokraft® erhöhte das Gewicht der Rhizosheath und der Knöllchen
A New Way of Identifying Biomarkers in Biomedical Basic-Research Studies
A simple, nonparametric and distribution free method was developed for quick identification of the most meaningful biomarkers among a number of candidates in complex biological phenomena, especially in relatively small samples. This method is independent of rigid model forms or other link functions. It may be applied both to metric and non-metric data as well as to independent or matched parallel samples. With this method identification of the most relevant biomarkers is not based on inferential methods; therefore, its application does not require corrections of the level of significance, even in cases of thousands of variables. Hence, the introduced method is appropriate to analyze and evaluate data of complex investigations in clinical and pre-clinical basic research, such as gene or protein expressions, phenotype-genotype associations in case-control studies on the basis of thousands of genes and SNPs (single nucleotide polymorphism), search of prevalence in sleep EEG-Data, functional magnetic resonance imaging (fMRI) or others
Microanatomy of the trophosome region of Paracatenula cf. polyhymnia (Catenulida, Platyhelminthes) and its intracellular symbionts
Marine catenulid platyhelminths of the genus Paracatenula lack mouth, pharynx and gut. They live in a symbiosis with intracellular bacteria which are restricted to the body region posterior to the brain. The symbiont-housing cells (bacteriocytes) collectively form the trophosome tissue, which functionally replaces the digestive tract. It constitutes the largest part of the body and is the most important synapomorphy of this group. While some other features of the Paracatenula anatomy have already been analyzed, an in-depth analysis of the trophosome region was missing. Here, we identify and characterize the composition of the trophosome and its surrounding tissue by analyzing series of ultra-thin cross-sections of the species Paracatenula cf. polyhymnia. For the first time, a protonephridium is detected in a Paracatenula species, but it is morphologically reduced and most likely not functional. Cells containing needle-like inclusions in the reference species Paracatenula polyhymnia Sterrer and Rieger, 1974 were thought to be sperm, and the inclusions interpreted as the sperm nucleus. Our analysis of similar cells and their inclusions by EDX and Raman microspectroscopy documents an inorganic spicule consisting of a unique magnesium–phosphate compound. Furthermore, we identify the neoblast stem cells located underneath the epidermis. Except for the modifications due to the symbiotic lifestyle and the enigmatic spicule cells, the organization of Paracatenula cf. polyhymnia conforms to that of the Catenulida in all studied aspects. Therefore, this species represents an excellent model system for further studies of host adaptation to an obligate symbiotic lifestyle
Statistical analysis and significance testing of serial analysis of gene expression data using a Poisson mixture model
<p>Abstract</p> <p>Background</p> <p>Serial analysis of gene expression (SAGE) is used to obtain quantitative snapshots of the transcriptome. These profiles are count-based and are assumed to follow a Binomial or Poisson distribution. However, tag counts observed across multiple libraries (for example, one or more groups of biological replicates) have additional variance that cannot be accommodated by this assumption alone. Several models have been proposed to account for this effect, all of which utilize a continuous prior distribution to explain the excess variance. Here, a Poisson mixture model, which assumes excess variability arises from sampling a mixture of distinct components, is proposed and the merits of this model are discussed and evaluated.</p> <p>Results</p> <p>The goodness of fit of the Poisson mixture model on 15 sets of biological SAGE replicates is compared to the previously proposed hierarchical gamma-Poisson (negative binomial) model, and a substantial improvement is seen. In further support of the mixture model, there is observed: 1) an increase in the number of mixture components needed to fit the expression of tags representing more than one transcript; and 2) a tendency for components to cluster libraries into the same groups. A confidence score is presented that can identify tags that are differentially expressed between groups of SAGE libraries. Several examples where this test outperforms those previously proposed are highlighted.</p> <p>Conclusion</p> <p>The Poisson mixture model performs well as a) a method to represent SAGE data from biological replicates, and b) a basis to assign significance when testing for differential expression between multiple groups of replicates. Code for the R statistical software package is included to assist investigators in applying this model to their own data.</p
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