Search results for "Field"
showing 10 items of 15048 documents
The Effect of Predator Population Dynamics on Batesian Mimicry Complexes.
2022
Understanding Batesian mimicry is a classic problem in evolutionary biology. In Batesian mimicry, a defended species (the model) is mimicked by an undefended species (the mimic). Prior theories have emphasized the role of predator behavior and learning as well as evolution in model-mimic complexes but have not examined the role of population dynamics in potentially governing the relative abundances and even persistence of model-mimic systems. Here, we examined the effect of the population dynamics of predators and alternative prey on the prevalence of warning-signaling prey composed of models and mimics. Using optimal foraging theory and signal detection theory, we found that the inclusion …
The impact of life stage and pigment source on the evolution of novel warning signal traits
2021
Our understanding of how novel warning color traits evolve in natural populations is largely based on studies of reproductive stages and organisms with endogenously produced pigmentation. In these systems, genetic drift is often required for novel alleles to overcome strong purifying selection stemming from frequency-dependent predation and positive assortative mating. Here, we integrate data from field surveys, predation experiments, population genomics, and phenotypic correlations to explain the origin and maintenance of geographic variation in a diet-based larval pigmentation trait in the redheaded pine sawfly (Neodiprion lecontei), a pine-feeding hymenopteran. Although our experiments c…
Log velocity profile and bottom displacement for a flow over a very flexible submerged canopy
2007
Management of shallow lagoons and salt marsh environments usually requires use of numerical models in order to understand the hydrodynamic characteristics of these basins. In order for these models to give reliable results one has to have good knowledge of the interaction between the flow and the aquatic vegetation, which strongly alters the hydrodynamic characteristics. Many experimental and theoretical studies are available in the technical literature, but, because of the very different vegetation and flow characteristics, they do not yet allow one to have a clear and general knowledge of the phenomena, in terms of both flow resistance and velocity distribution. The latter is very importa…
An Evaluation Model for Social Work with Substance Abusers
2016
In this article, the research topic is to develop an evaluation model for social work with substance abusers. It is studied by presenting an example of how the evaluation process could be carried out in practice. The study has been implemented with the Department of Social Services and Health Care’s Centre for Recovering Substance Abusers in Finland (RSA Centre). The term “evaluation model” refers to a way of collecting client follow-up information and the way the information is used to develop social work practices. Firstly it is described, how the evaluation model was created at the RSA Centre. Secondly, some results are lifted up to show, what kind of information were used. Finally, it i…
Cluster visual field progression and its relationship with optic disc changes
2015
Purpose Glaucoma diagnosis and follow up of progression is often based on structural and functional assessments. This study aimed to assess clustered progression and evaluate its correlation with the corresponding disc changes (RA sectors) obtained from HRT examinations. Methods 51 eyes from OHT and glaucoma patients with a minimum of 5 reliable visual ᴀ밄eld tests (HFA II i 24-2) and HRT with a follow-up >4 years were analyzed retrospectively. Linear regression of clusters deᴀ밄ned by the Glaucoma Hemiᴀ밄eld Test (GHT) was performed based on the mean threshold in each cluster. Global and sectoral rates of change in RAs were assessed and correlated with functional clustered measures. Cluste…
Anatomic and functional follow-up of patients with an idiopathic epiretinal membrane and a preserved visual acuity
2013
Purpose: To determine the anatomic and functional retinal modifications in patients with an idiopathic epiretinal membrane (ERM) and a preserved visual acuity (VA).Methods: Monocentric, prospective study in 24 eyes of 24 patients with an ERM and a VA better than 20/25. Recorded data were best corrected VA on ETDRS scale, retinal anatomic lesions on spectral-domain OCT, retinal sensitivities on microperimetry and macular and foveal thicknesses at 0 and 6 months.Results: At inclusion, mean VA was 84 ± 5 letters, mean macular sensitivity was 14.0 ± 1.4 decibels (dB) and mean foveal sensitivity was 14,4 ± 1,5 dB. Mean macular thickness was 351 ± 34 µm and mean foveal thickness was 348 ± 66 µm. …
Motion perception in early glaucoma
2013
Purpose: The aim of our study was to underline the changes in the movement perception for early glaucoma. Our working hypothesis consisted in inquiring if the impairment of the magnocellular pathway may modify the movement perception capabilities in the visual field, more particularly in its peripheral area.Methods: We included 14 healthy subjects and 14 patients with early primary open angle glaucoma. A moving target was presented on a semicircular screen (1.8 m diameter); participants were asked to localize the Ending Point (EP) of each movement. Each stimulus consisted in a white dot (0,72° of diameter) moving horizontally with the imposed velocity profile. Two different laws of motion w…
Il senso del vivere, ovvero la vita come oggetto di studio antropologico
2017
Si può considerare l’esistenza un campo antropologico a tutti gli effetti? È fuor di luogo parlare di campo – esotizzante o meno che sia – a proposito di esistenza? Quali strumenti teorici utilizzare al fine di cogliere il senso dell’esistenza? In questo saggio, si focalizza l’attenzione sulla nozione di esistenza e sulle componenti che la caratterizzano in relazione ad altre nozioni ugualmente importanti in antropologia quali cultura, esperienza, potere, sapere, etc. Il tentativo è di trovare risposte mettendo a fronte questioni centrali in antropologia in modo non oppositivo bensì per tratti continui e/o discontinui: ‘religione come senso quieto del vivere’ e ‘ribellione ai codici dominan…
Voltammetric determination of platinum in perfusate and blood: Preliminary data on pharmacokinetic study of arterial infusion with oxaliplatin
2012
Abstract Because Platinum Group Elements have found widespread use in catalytic converters in cars and as chemotherapeutic agent, interest in the development of reliable analytical methods is carried out in order to monitor these analita in humans to protect the citizen's health. Considering that information on the levels of many trace elements in biological matrices is scarce and for many non-essential elements, baseline levels in the population, and especially in those particularly exposed to the risk are lacking, in this paper we optimize an analytical method for biological matrices, using a voltammetric technique to measure the concentration of Pt in blood and perfusate. The amount of P…
Relationship between volume and energy of vector fields
2001
Abstract A unified study of energy and volume functionals is presented here by determining the critical points of a functional that extends simultaneously energy and volume and that is defined on the product of the manifold of smooth maps C∞(M,N) times the manifold M of riemannian metrics on M. The restriction of this functional to different submanifolds of the space of vector fields X (M)× M is also considered, and used to study several functionals generalizing volume and energy or total bending of vector fields