Search results for "population"
showing 10 items of 9945 documents
À bas la sélection ! Misère de la critique
2019
International audience; La critique de la sélection à l'entrée de l'université repose sur une vision misérabiliste des étudiants de milieu populaire et ne remet pas en question les inégalités au sein du système d'éducation. Il existe sans doute mille bonnes raisons d'être hostile à Parcoursup et à la réforme du baccalauréat, comme il existe de solides raisons de protester contre les conditions de travail des professeurs, des enseignants-chercheurs et des étudiants… Le propos de ce texte n'est pas de participer aux débats sur le bien-fondé des réformes ; il n'est ni de les défendre ni de les contester, mais d'interroger les cadres de la critique de la sélection que ces réformes sont censées …
Population of nuclides with Z≥98 in multi-nucleon transfer reactions of 48Ca + 248Cm
2019
The results for nuclei above curium, produced in multi-nucleon transfer reactions of 48Ca + 248Cm at the velocity filter SHIP of GSI Darmstadt, are presented. Spontaneous fission and α-activities have been used to study the population of nuclei with lifetimes ranging from few milliseconds to several days. We observed several, relatively neutron-rich isotopes with atomic numbers Z≥98; among them a weak 224 millisecond activity which we tentatively attributed to 260No. The measured cross-sections of the observed nuclei give hope that multi-nucleon transfer reactions are a way to reach new neutron-rich heavy and superheavy nuclei, which are not accessible in other reactions. We compare our res…
Przeciwdziałanie depopulacji Opolszczyzny
2021
W województwie opolskim od dawna obserwuje się niekorzystną sytuację demograficzną. Niskie wskaźniki dzietności oraz ujemne saldo migracji sprawiają, że Opolszczyzna harakteryzuje się jednym z najwyższych w kraju wskaźników depopulacji. Dostrzegając związane z tym zagrożenia samorządy województwa postanowiły wpłynąć na ich ograniczenie. Najwyższa Izba Kontroli zbadała1 działania podejmowane w Urzędzie Marszałkowskim Województwa Opolskiego, Urzędzie Miasta Opola oraz Urzędzie Miejskim w Nysie. Z ustaleń wynika, że możliwiły one poprawę warunków życia mieszkańców, jednak jak dotąd nie doprowadziły do odwrócenia negatywnych trendów demograficznych.
Are habitat loss, predation risk and climate related to the drastic decline in a Siberian flying squirrel population? A 15 year study
2014
To devise effective conservation actions, it is important to know which factors are associated with the population parameters of a declining population. Using mark–recapture methods, we estimated the annual population size, growth rate and survival probability of an ear-tagged flying squirrel population over a 15-year period in a 4,500 ha study area in western Finland. The species is considered vulnerable, but detailed knowledge concerning population sizes or trends is lacking. The population parameters and changes therein were regressed against habitat availability, an indicator of predation pressure, and mean winter temperature (an indicator of climate change), to reveal potential reasons…
L'accès des ménages aux services dans l'espace périurbain francilien
2008
The access of populations to services, out of the dense urban centres, is marked by the retreat of the services of proximity to which populations and local councillors appear particularly attached. However, in peri-urban spaces, this remote setting of the resources compared to the populations is the result of the generalized adoption of the automobile standard for mobility and accessibility. That has two effects: first a disintegration of the local offer, then a disintegration of the modal alternatives to the private car, because of relocalizations of services and populations which privilege car for their accessibility and call into question their access by other modes like public transport…
The effect of inbreeding rate on fitness, inbreeding depression and heterosis over a range of inbreeding coefficients
2014
Understanding the effects of inbreeding and genetic drift within populations and hybridization between genetically differentiated populations is important for many basic and applied questions in ecology and evolutionary biology. The magnitudes and even the directions of these effects can be influenced by various factors, especially by the current and historical population size (i.e. inbreeding rate). Using Drosophila littoralis as a model species, we studied the effect of inbreeding rate over a range of inbreeding levels on (i) mean fitness of a population (relative to that of an outbred control population), (ii) within‐population inbreeding depression (reduction in fitness of offspring fro…
Flamingo studies: a general introduction.
2017
28 pages; International audience; Flamingos are among the most amazing birds in the world. The first part of this chapter provides a general introduction to the various extant species of flamingos, including their physical descriptions, unique characteristics, numbers in the wild, and geographical distributions. The second part depicts a brief history of the discovery and scientific study of flamingos, from the earlier accounts dating from the 16th century to the development of the first long-term studies of banded populations in the second half of the 20th century. The third and final part of this chapter offers some perspectives for future research.
The temporal variation in Siberian flying squirrel (Pteromys volans) population size
2011
Human land use causes declines of natural populations, for example, by loss of habitat area. Additionally, habitat fragmentation can cause the population size to decline more than is expected based on the area lost. Some ecological processes, such as demographic stochasticity and Allee effect, can expose already small populations to further decline. The endangered Siberian flying squirrel (Pteromys volans) has suffered from intensive forestry in Finland. In this thesis I estimated the size and growth rate of a local flying squirrel population living in nest boxes in Alavus using 15-year mark-recapture data. I regressed the estimated population size against habitat availability to detect rel…
Data from: The effect of inbreeding rate on fitness, inbreeding depression and heterosis over a range of inbreeding coefficients
2014
Understanding the effects of inbreeding and genetic drift within populations and hybridization between genetically differentiated populations is important for many basic and applied questions in ecology and evolutionary biology. The magnitudes and even the directions of these effects can be influenced by various factors, especially by the current and historical population size (i.e., inbreeding rate). Using Drosophila littoralis as a model species, we studied the effect of inbreeding rate over a range of inbreeding levels on 1) mean fitness of a population (relative to that of an outbred control population), 2) within-population inbreeding depression (reduction in fitness of offspring from …
Aspetti demografici
2019
Il VI Rapporto Migrazioni in Sicilia fotografa una situazione radicalmente mutata, non soltanto nella nostra isola, ma in tutto il paese e a livello sovranazionale. Se da un lato la rinnovata attenzione verso le problematiche legate ai cambiamenti climatici ha portato alla nascita di un processo dal basso che ha coinvolto milioni di giovani in tanti paesi, dall’altro l’adozione di misure estreme per bloccare i flussi migratori (sempre più, peraltro, causati nel mondo dagli stessi cambiamenti climatici), ha avviato in altrettanti paesi un processo inverso, che nega l’efficacia di un approccio globale, anzi, ne teme gli effetti.