4,695 research outputs found
Favourable areas for expansion and reintroduction of Iberian lynx accounting for distribution trends and genetic diversity of the European rabbit
Although on a local scale Iberian lynx distribution is determined by the availability of prey rabbits, recent modelling analyses have uncovered broad-scale disagreements between these two species’ distribution trends. These analyses showed also that the lynx had become restricted to only a fraction of the rabbit’s genetic diversity, and that this could be jeopardising its survival in the face of environmental hazards and uncertainty. In the present paper, a follow-up was carried out through the building of lynx and rabbit distribution models based on the most recent Spanish mammal atlas. Environmental favourability values for lynx and rabbit were positively correlated within the lynx’s current distribution area, but they were negatively correlated within the total Spanish area where lynx used to occur in the 1980’s. Environmental favourability for rabbits was significantly higher where lynx maintains reproductive populations than where it recently disappeared, indicating that rabbit favourability plays an important role and can be a good predictor of lynx persistence. The lynx and rabbit models were extrapolated to predict favourable areas for both species in Spain as well as in Portugal, on the original scale of the distribution data (10x10 km) and on a 100 times finer spatial resolution (1x1 km). The lynx and rabbit models were also combined through fuzzy logic to forecast the potential for lynx occurrence incorporating information on favourable areas for its main prey. Several areas are proposed as favourable for lynx expansion or re-introduction
The Research, Design and Development of a prototype Liquid Nitrogen Cryotherapy Device combining Electrical Stimulation and Heat
With a growing consumer driven cryotherapy market and its widespread applications in the medical industry a leading British cryotherapy clinic and equipment distributer have been researching the potential benefits to health and wellbeing of a novel procedure combining localised cryotherapy with electrical stimulation and heat. The project oversaw the development of a proof of principal prototype to allow further testing and technical development with a view to manufacture. Detailed in the project report is the research into multiple systems including a framework, heating system, Liquid Nitrogen pump and bodywork. An initial working proof of principal prototype was developed establishing an architecture for the combined machine considering function and user ergonomics
Ammonia effects on proton conductivity properties of coordination polymers
Crystalline metal phosphonates are referred to as a type of structurally versatile coordination polymers [1]. Many of them contain guest molecules (H2O, heterocyclics, etc.), acidic sites and, furthermore, their structure can be also amenable for post‐synthesis modifications in order to enhance desired properties [2].
In the present work, we examine the relationships between crystal structure and proton conductivity for several metal phosphonates derive from multifunctional ligands, such as 5-(dihydroxyphosphoryl)isophthalic acid (PiPhtA) [3] and 2-hydroxyphosphonoacetic acid (H3HPAA). Crystalline divalent metal derivatives show a great structural diversity, from 1D to 3D open-frameworks, possessing hydrogen-bonded water molecules and acid groups. These solids present a proton conductivity range between 7.2·10-6 and 1.3·10−3 S·cm-1. Upon exposure to ammonia vapor, from an aqueous solution, solid state transformations are observed accompanied of enhance proton conductivities. The stability of these solids under different environment conditions (temperature and relative humidities) as well as the influence of the ammonia adsorption on the proton conduction properties of the resulting solids will be discussed.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech
Analyzing Marketing Margins and Their Implications in Improving Performance of Small-Scale Producers in the Calamansi Chain in Region XI, Southern Philippines
Due to its wide range of uses and profitability, calamansi or calamondin (Citrofortunella microcarpa) is considered a high-value crop of the Philippines. But while there are many studies on the various uses of calamansi parts and technologies developed to help farmers, there is a dearth of studies on the structure and operation of the calamansi marketing chain and analysis of marketing margins of producers and other intermediaries. The present study aimed to examine marketing margins to understand the marketing system of the calamansi industry in Region XI, Southern Philippines, and identify opportunities, challenges, and solutions to improve the chain. A price transmission model was estimated using secondary data and supplemented by calculation of net margins for farmers, wholesalers, processors, and retailers using primary data collected from key informants. Results show that farm, wholesale, and fuel prices significantly explained changes in selling or retail prices. Price transmission elasticity is higher from farm to wholesale than from farm to retail, which implies that changes in farm prices are reflected more in wholesale than retail prices. Farmers received better margins even though calamansi is always subjected to seasonality of prices. Processors and wholesalers also earned positive net margins, but some retailers incurred negative net margins because of incidence of shrinkage/wastage. Given that this occurs very rarely, and with better management, retailers can still expect to gain positive net margins. Major actors in the chain may benefit by effectively managing costs, particularly post-production and wastage costs. A package of assistance that includes technology improvement, access to market, and credit is necessary to help farmers, as well as intermediaries, enhance productivity and manage costs to improve their performance in the chain
Obtaining environmental favourability functions from logistic regression
Logistic regression is a statistical tool widely used for predicting species’
potential distributions starting from presence/absence data and a set of independent
variables. However, logistic regression equations compute probability values based
not only on the values of the predictor variables but also on the relative proportion
of presences and absences in the dataset, which does not adequately describe the
environmental favourability for or against species presence. A few strategies have
been used to circumvent this, but they usually imply an alteration of the original data
or the discarding of potentially valuable information. We propose a way to obtain
from logistic regression an environmental favourability function whose results are not
affected by an uneven proportion of presences and absences. We tested the method
on the distribution of virtual species in an imaginary territory. The favourability models
yielded similar values regardless of the variation in the presence/absence ratio.
We also illustrate with the example of the Pyrenean desman’s (Galemys pyrenaicus)
distribution in Spain. The favourability model yielded more realistic potential distribution
maps than the logistic regression model. Favourability values can be regarded
as the degree of membership of the fuzzy set of sites whose environmental conditions
are favourable to the species, which enables applying the rules of fuzzy logic to distribution
modelling. They also allow for direct comparisons between models for species
with different presence/absence ratios in the study area. This makes themmore useful
to estimate the conservation value of areas, to design ecological corridors, or to select
appropriate areas for species reintroductions
Chain Homotopies for Object Topological Representations
This paper presents a set of tools to compute topological information of
simplicial complexes, tools that are applicable to extract topological
information from digital pictures. A simplicial complex is encoded in a
(non-unique) algebraic-topological format called AM-model. An AM-model for a
given object K is determined by a concrete chain homotopy and it provides, in
particular, integer (co)homology generators of K and representative (co)cycles
of these generators. An algorithm for computing an AM-model and the
cohomological invariant HB1 (derived from the rank of the cohomology ring) with
integer coefficients for a finite simplicial complex in any dimension is
designed here. A concept of generators which are "nicely" representative cycles
is also presented. Moreover, we extend the definition of AM-models to 3D binary
digital images and we design algorithms to update the AM-model information
after voxel set operations (union, intersection, difference and inverse)
Acção do vento sobre torres: análises comparativas entre RSA e Eurocódigos
Neste trabalho indicam-se as principais diferenças que se podem observar ao nível da acção do vento, entre o Regulamento de Segurança e Acções (RSA) e Eurocódigos (EC), quando aplicáveis à análise e dimensionamento de torres. Para tal, procede-se à análise com-parativa de diversos parâmetros, colocando-se comentários gerais sobre cada um deles, para um melhor entendimento sobre a sua abordagem e filosofia. Finalmente, são apresentados, confrontados e discutidos os resultados obtidos de acordo com cada uma das normas mencio-nadas, tendo como base o caso de estudo de uma torre utilizada para radiocomunicações
Principais anomalias observadas em torres para radiocomunicações em Portugal
As torres são um dos principais suportes físicos para a instalação de equipamentos de rádio, utilizados para a emissão de ondas electromagnéticas que permitem serviços diver-sos, tais como rádio, televisão ou comunicações móveis. Em Portugal, na década de 90, houve uma enorme procura por este tipo de estruturas, sobretudo como resultado do enorme cresci-mento da cobertura para utilização em redes de comunicações móveis. Este trabalho pretende apresentar as principais anomalias observadas neste tipo de estruturas em Portugal
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