1,721,078 research outputs found
Il metodo Lipman. Una metodologia educativa per il dialogo intergenerazionale
No full textNel contesto contemporaneo, caratterizzato da una diffusa complessità e da crescente ostilità, un'efficace educazione degli adulti deve connotarsi come un'incessante opportunità di risignificazione esistenziale, sia a livello personale che comunitario. Inoltre, deve sostenere le persone nell'acquisizione di conoscenze e fornire loro nuovi strumenti. Questa ricerca vuole porre in evidenza le potenzialità del metodo creato da Matthew Lipman per l'educazione degli adulti. In particolare vuole mostrare il suo possibile uso per il dialogo intergenerazionale tra adulti e adolescenti.In the present scenario, characterized by a widespread complexity and an increasing hostility, an efficient adult education should connote itself as a constant opportunity of renewing the existential meaning of life, both on an individual and on a community level. Moreover, it should support people in acquiring knowledge and new technical devices. This research is s aimed at highlighting the potentialities of the method created by Matthew Lipman for adult education. In particular I will explain its use in intergenerational dialogue paths between adults and adolescents
Inbreeding and outbreeding depression in geographical parthenogens Heterocypris incongruens and Eucypris virens (Crustacea: Ostracoda)
No full textHeterocypris incongruens and Eucypris virens are geographic parthenogens inhabiting temporary ponds. Several authors proposed that, after the last glaciation, asexual lineages would spread throughout Europe more efficiently than sexual ones. The range expansion, that followed a metapopulation dynamics characterized by genetic bottlenecks and subsequent inbreeding / outbreeding depression, had strong negative fitness consequences in sexuals. Using controlled crosses we estimated inbreeding and outbreeding depression in sexual populations of H. incongruens and E. virens and compared the experimental reproduction rate in sexual and asexual females of both species. Inbreeding depression varied according to species and fitness components but, in general, were not significantly different between inbred and outbred crosses. In H. incongruens, inbred crosses produced a higher percentage of resting eggs and had higher fecundity than intrapopulation outbred crosses. Reproduction rate in asexuals of both species was about twice than in sexuals. Our data do not support the hypothesis that sexual populations exhibit inbreeding depression in geographic parthenogens. However, outbreeding depression and the lower efficiency of sexuals in establishing new populations may account for the role of metapopulation dynamics in geographic parthenogenesis of both species
The clonal ecology of Heterocypris incongruens (Ostracoda): life-history traits and photoperiod.
No full textEffects of mother presence and photoperiod on egg production and hatching of two asexual lineages of Eucypris virens (Crustacea: Ostracoda)
No full textParental care is a source of maternal effects and the lack of genetic variation expected among clonal
organisms makes them ideal material for investigating environmental mother effects. Using laboratory experiments
at two photoperiods, 16:8 and 6:18 L:D, we evaluated the effect of mother’s age and mother presence/absence, on
the production of resting eggs and on egg development time in two different clonal lineages of Eucypris virens from
vernal pools from different latitudes (from Ventina, Italy and from Bramhope, UK). Mother presence/absence had a
clear effect on egg hatching time, although, as expected, hatching was strongly influenced by photoperiod. Extended
daylight, a reliable cue of incoming drought, induces dormancy. The effect was stronger in the Southern clone
(only resting eggs were produced and the effect of mother presence on hatching could not be tested). The Northern
clone laid both resting and non resting eggs and mother presence produced a small but significant delay in hatching.
In short daylight, a reliable cue of incoming favourite environmental conditions, both clones produced both resting
eggs and non-resting eggs. Mother presence/absence had a strong, opposite effect in the two clones: hatching was
delayed by her presence in the Southern and by her absence in the Northern. We found no effect of mother age on
proportion of resting eggs and on egg development time. We discuss our results in terms of environmental predictability
and suggest the contrasting effect of mother presence in shorter daylight as a possible mechanism for the
expression of a risk spreading strategy
CONFLITTUALITA' E GENITORIALITA' NELLA SEPARAZIONE: UNA LETTURA PEDAGOGICA
No full textThe research studies on adult couples separated compared to the changes recorded in the history of life related to the event of separation, to present choices of values and attitudes, before and after the event, and the issues and changes made since separation in the exercise of the parental role
DIVERSITÀ GENETICA E MORFOLOGICA IN POPOLAZIONI CIRCUMMEDITERRANEE DEL GENERE BRANCHIPUS
No full textLarval identification of two syntopic species Branchipus schaefferi and Tanymastix stagnalis (Crustacea, Anostraca) sheds light on their pattern of coexistence.
No full textIn the present study we applied a discriminant function analysis to distinguish two fairy shrimp species, Branchipus schaefferi and Tanymastix stagnalis (Anostraca), co-occurring in Lago dell’Orso in central Italy. Our aim was to obtain information on the pattern of coexistence of these two species to investigate their syntopy since early larval stages. To identify the larvae of the two species we used six discriminant functions, one for each larval stage
considered (nauplius, four metanauplius stages and juvenis), and based on morphometric analyses and
measurements of different traits (thoracic appendages, body length, length of first antenna, length of head,
thorax length and length of furca). The pool was visited at weekly intervals during two time periods for
a total of 4 years (1995–1996 and 2000–2001) and physical and chemical variables (water level, water
and air temperature, pH and conductivity) were recorded. A total of 1067 specimens were collected,
measured and morphometrically identified. B. schaefferi was more abundant and persistent than T.
stagnalis. At any stage, T. stagnalis was bigger than B. schaefferi and this difference may justify niche
differentiation between coexisting species. Difference in size might be linked to difference in life-span as B.
schaefferi reproduced earlier and at a smaller size than T. stagnalis. When the hydroperiod is short, B.
schaefferi might be the only species to produce resting eggs in time for reproduction. On the other hand, T.
stagnalis may have an advantage in the longest hydroperiods. In an ephemeral seasonal pond such as
Lago dell’Orso, coexistence can be fostered and competitive exclusion can be prevented as a result of
seasonal environmental changes
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