Search results for "models"
showing 10 items of 8211 documents
“To Own, or not to Own?” A multilevel analysis of intellectual property right policies' on academic entrepreneurship
2017
The political environment around universities has led them to create an infrastructure to manage academic inventions. While some consider that the advantages of a university entrepreneurial structure outweigh any potential negative effects, others question their detrimental effect on academic scientists’ entrepreneurial behavior. However, this debate remains unresolved as none of these two views have been fully empirically supported. Using multilevel models for a population of 2230 professors in 27 universities in Canada (82 individuals per unit on average), we test the effect of three features of institutional intellectual property right policy characteristics, namely, property rights (own…
Set Membership (In) Validation of nonlinear positive models for biological systems
2006
The complexity of biology needs quantitative tools in order to support and validate biologists intuition and traditional qualitative descriptions. In this paper, Nonlinear Positive models with constraints for biological systems are validated/invalidated in a worst-case deterministic setting. These models are usefull for the analysis of the DNA and RNA evolution and for the description of the population dynamics of viruses and bacteria. The conditional central estimate and the Uncertainty Intervals are determined in order to validate/invalidate the model. The effectiveness of the proposed procedure has been illustrated by means of simulation experiments.
A potential role for water in the modulation of oxygen-binding by tarantula hemocyanin
2003
Hemocyanin from the tarantula Eurypelma californicum is a large respiratory protein with an exceptional high cooperativity. In contrast to hemocyanins from other species, no physiological allosteric effectors other than protons have been identified so far for this 24-meric oligomer. Here we report for the first time the mediating effects of water activity on the oxygen binding properties of a hemocyanin. Oxygen binding curves were measured in presence of several concentrations of glycine and sucrose since both substances reduce water activity. A pronounced shift of the p(50) was observed in both cases but in different directions: adding sucrose shifts the p(50) towards lower values whereas …
On the qualitative analysis of the solutions of a mathematical model of social dynamics
2006
Abstract This work deals with a family of dynamical systems which were introduced in [M.L. Bertotti, M. Delitala, From discrete kinetic and stochastic game theory to modelling complex systems in applied sciences, Math. Models Methods Appl. Sci. 7 (2004) 1061–1084], modelling the evolution of a population of interacting individuals, distinguished by their social state. The existence of certain uniform distribution equilibria is proved and the asymptotic trend is investigated.
Identification of Replicator Mutator models
2006
The complexity of biology literally calls for quantitative tools in order to support and validate biologists intuition and traditional qualitative descriptions. In this paper, the Replicator-Mutator models for Evolutionary Dynamics are validated/invalidated in a worst-case deterministic setting. These models analyze the DNA and RNA evolution or describe the population dynamics of viruses and bacteria. We identify the Fitness and the Replication Probability parameters of a genetic sequences, subject to a set of stringent constraints to have physical meaning and to guarantee positiveness. The conditional central estimate is determined in order to validate/invalidate the model. The effectivene…
Ecomorphological predictors of natal dispersal distances in birds.
2008
1. Dispersal is one of the key ecological parameters but it is very difficult to quantify directly. As a consequence, empirical studies often ignore dispersal or use indirect measures. 2. Ringing data have previously been used to estimate the natal dispersal distances of 47 British passerine bird species. This provides an excellent opportunity to examine the potential of various indirect measures to predict natal dispersal distances in British birds. 3. We use a phylogenetic comparative framework and single- and multipredictor models including ecomorphological, behavioural or ecological traits to predict natal dispersal distance. 4. A multipredictor model that includes Kipp's distance (a me…
Application of a Bayesian Spatiotemporal Surveillance Method to NYC Syndromic Data
2014
Incorporating prior knowledge (e.g., the spatial distribution of zip codes and background population effects) into a model using Bayesian methods could potentially improve outbreak detection. We adapted a previously described Bayesian model-based spatiotemporal surveillance technique to daily respiratory syndrome counts in NYC Emergency Department data in 2009, the year of the H1N1 influenza pandemic. Citywide, 56 alarms were produced across 15 zip codes, all during days of elevated respiratory visits. Future work includes evaluating our choice of baseline length, considering other alarm thresholds, and conducting a formal evaluation of the method across five syndromes in NYC.
Dalla grammatica alle grammatiche dell’italiano: un’analisi in diacronia dei testi di educazione linguistica (1975-2015)
2021
Il contributo che si propone ha per oggetto un’analisi di un campione di libri di testo di educazione linguistica, prodotti dall’editoria scolastica italiana negli ultimi quarant’anni, al fine di verificare quanto del dibattito teorico sulle varietà e sulle linee di tendenza dell’italiano contemporaneo sia stato accolto negli anni dalla manualistica scolastica e quale “modello di lingua” sia oggi presentato ai discenti. È noto che il panorama linguistico contemporaneo rende inapplicabile un modello grammaticale di tipo tradizionale che non tenga conto del sapere linguistico del parlante e che non faccia dialogare la norma con gli usi concreti. Per esaminare in che modo si siano modificati g…
A New Method to Reconstruct Quantitative Food Webs and Nutrient Flows from Isotope Tracer Addition Experiments
2020
Understanding how nutrients flow through food webs is central in ecosystem ecology. Tracer addition experiments are powerful tools to reconstruct nutrient flows by adding an isotopically enriched element into an ecosystem and tracking its fate through time. Historically, the design and analysis of tracer studies have varied widely, ranging from descriptive studies to modeling approaches of varying complexity. Increasingly, isotope tracer data are being used to compare ecosystems and analyze experimental manipulations. Currently, a formal statistical framework for analyzing such experiments is lacking, making it impossible to calculate the estimation errors associated with the model fit, the…
Chirality of 135 Nd reexamined : Evidence for multiple chiral doublet bands
2019
One new pair of positive-parity chiral doublet bands have been identified in the odd-A nucleus 135Nd which together with the previously reported negative-parity chiral doublet bands constitute a third case of multiple chiral doublet (MχD) bands in the A ≈ 130 mass region. The properties of the MχD bands are well reproduced by constrained covariant density functional theory and particle rotor model calculations. The newly observed MχD bands in 135Nd represents an important milestone in supporting the existence of MχD in nuclei. peerReviewed