Abstract Impulsivity is a variable that has been associated with drug use. This study analyzes impulsivity from two different paradigms, one considering it as a trait and the other based on its ...behavioral correlates, such as disinhibition and impulsive decision-making in the treatment prognosis (maintain abstinence, relapse and dropout) of smokers after outpatient treatment. The participants in the study were 113 smokers who requested treatment for nicotine addiction. They were assigned to three groups according to whether or not they remained abstinent one month after beginning treatment; thus, group 1 was abstinent, group 2 had relapsed, and group 3 had dropped out of treatment. The participants filled out the Semi-structured Interview for Smokers , the Fargerström Test for Nicotine Dependence , the Temperament and Character Inventory-Revised (TCI-R) and the Delay Discounting Task (DDT). The Delay Discounting variable presents lower scores in the dropout group than in the relapse and abstinent groups, with the highest scores in the relapse group. Differences were also found on the Harm Avoidance (HA) variable, with lower scores in the dropout group compared to the relapse group. The importance of these results lies in the consideration of the smoker’s personality profile in order to prevent both dropout and relapse.
In this study we use a projection matrix model of order
n of an uneven-aged beech stand to analyse how the width of the diameter (physical tree diameter) classes
d influence the population growth ...rate
λ
0, and to obtain the sensitivity and the elasticity of
λ
0 with respect to
d. Numerical computations using systematic variations in
d and
n (where
n represents the number of diameter classes), three levels of diameter growth, three levels of stand basal area,
G
=
20, 22 and 24
m
2/ha, and three levels of recruitment,
R
=
200, 520 and 840
stems/ha, were conducted. The lowest values for
λ
0, sensitivities (∂
λ
0/∂
d) and elasticities (∂
λ
0/
λ
0)/(∂
d/
d), were obtained at the lowest width of the diameter classes,
d
=
5
cm. The results have also shown that: (a) the estimation of
λ
0 was not significantly affected by small or even moderate changes in
n and/or
d; (b) (∂
λ
0/∂
d) and (∂
λ
0/
λ
0)/(∂
d/
d) increased with increasing
d; (c) within each quality level (diameter growth level),
λ
0 increased with increasing
R and decreased with increasing
G, (∂
λ
0/∂
d) decreased with increasing
R and increased with increasing
G, and (∂
λ
0/
λ
0)/(∂
d/
d) decreased with increasing
R and increased with increasing
G. We suggest that narrow size categories should be used in this model to obtain conservative estimates of
λ
0 and sustainable harvest rates, with minimum sensitivities and elasticities, although the results were not substantially affected by small or even moderate changes in the width and/or number of the diameter classes.
Aim of study: The aim of this work is to test the positive effect of a substantially developed resin sector on rural demographic evolution. This work shows how in the period between 1970 and 2010 the ...demographic decline in the interior regions of Spain was more pronounced in areas characterized by the importance of resin-producing forest stands compared to other nearby rural municipalities where this natural resource is not present.Area of study: The study area consists of a set of rural municipalities in Central Spain, both resin and non-resin producing, in the provinces of Segovia, Avila, Valladolid, Burgos, Soria, Cuenca and Guadalajara.Material and methods: The relationship between resin production and population in resin and non-resin producing municipalities was modeled by means of linear regression analysis.Main results: Generally speaking, between 1950 and 1970 the production of resin halted demographic decline in the regions where this activity was substantially developed. However, when the resin sector entered into crisis in the 1970s, and the economic repercussions of this activity gradually ceased to be felt, the demographic decline in the regions which had been involved in resin production was much more acute than in other non-resin-producing rural areas.Research highlights: This work shows the relationship between resin extraction activity and population evolution in rural municipalities. Sustainable resin exploitation can contribute to the maintenance and development of rural communities, and should be used as a tool for generating employment in rural areas.Key words: demography; economic crisis; resin sector; rural development.
This study proposes a discrete optimal control model to obtain harvest strategies that maximize the net present value (NPV) of the timber harvested from uneven-aged Pinus nigra stands located in the ...Spanish Iberian System, between two stable positions. The model was constructed using an objective function that integrates financial data on the harvesting operations with a matrix model describing the population dynamics. The initial and final states are given by the stable diameter distribution of the stand, and the planning horizon is 70 years. The scenario analysis corresponding to the optimal solutions revealed that the stand diameter distribution does not deviate substantially from the equilibrium position over time and that the NPV for the optimal harvesting schedule was always greater than the NPV for the “sustainable/stable” harvesting strategy. The NPV increase for the different scenarios is between 5.36% and 14.43%, showing a greater increase in higher site index scenarios and higher recruitments.
This study proposes a model based on discrete optimal control for estimating the optimal rotation age of Pinus nigra in the Spanish Iberian System. The model was constructed using the NPV ...(alternately LEV) of forest management as objective function and a model of stand evolution represented by a finite difference equation. The optimal rotation ages obtained corresponding to the 2-4% discount rate interval were between 60 and 100 years for the NPV strategy (50 and 70 years for the LEV strategy). With regard to the optimal management schedule, the results have shown the need to intensify the harvesting at 40-60 years in order to maximize the production of posts in view of the high price they command on the market.
This paper discusses the fluid flow evolution in the Veracruz petroleum province of eastern Mexico based on results of an integrated diagenetic, sedimentological and structural analysis. The area ...progressively changed from passive foreland towards an active fold-and-thrust belt into a passive belt with infill of the foreland basin and finally underwent transpressional deformation. This varied kinematic evolution resulted in numerous fluid flow events, among which were four different petroleum migration pulses.
Modelling Of Compact Evaporators And Condensers Corberan, J M; Fernandez de Cordoba, P; S. Ortuno V. Ferri J. Gonzalvez ...
WIT Transactions on Engineering Sciences,
01/2000, Letnik:
27
Journal Article
Odprti dostop
In this paper a model for compact evaporators and condensers is presented. The flow along a channel of a compact HE is considered to be 2-D and split into separated 1-D paths. Then, every 1-D flow ...path is discretised in as many elements as required. First, both fluid flow evolution along the heat exchanger are calculated through the integration of the 1-D conservation equations for single or two phase flow, assuming that wall temperatures are known. This calculation is performed through an explicit finite volume scheme, following the flow path. Once the temperature field for both fluids is calculated, then, the wall temperatures are obtained from the integration of the wall energy equation
Such cytomegalovirus antibodies as the IgG and IgM are investigated in the present work. Investigation was carried out on 301 sera of fertile aged women (between 18 to 35 years of age) under the ...enzyme-linked immunosorbent assay (ELISA). Only one dilution has been made i.e. 1:40 and the final dilution was worked out from regression graph obtained from a previously titred human positive serum analysis; IgG antibodies were found in 265 cases (88%), appearing IgM antibodies in 4 of them, with the remaining 36 cases showing neither IgG nor IgM antibodies (12%). These results were compared with those obtained in other countries and the importance of the serological diagnosis to this virus was pointed out.
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