Numerical study of size-structured population models: a case of Gambussia affinis

We study, from a numerical point of view, some properties of a model which describes the evolution of a population of Gambussia affinis. Our model includes sufficiently smooth vital functions. First we select, among four numerical methods of second order, the most appropriate in terms of adaptation to the problem. The most efficient method also reveals new properties of the model for long times, such as the tendency to periodicity, obtained with different initial conditions. We also discuss some advantages and deficiencies of the model.     

Stratégies techniques dans le Paléolithique Moyen du sud-est des Pyrénées

In this article, the lithic reduction systems from Middle Paleolithic levels at Roca dels Bous and Tragó are presented. These two sites are located in the South-eastern Pyrenees in Catalunya (Spain) and yield Mousterian levels which are attributed to MIS 3 and MIS 5. At the two studied sites, there is coexistence between expedient knapping systems and more complex techniques such as the Levallois method. Furthermore, cores are heavily exhausted, showing a pattern that cannot be explained by the absence or scarcity of raw material. This technical pattern can be traced across several Mousterian assemblages in the South-eastern Pyrenees, suggesting technocognitive continuity in the Middle Palaeolithic during the Upper Pleistocene, in which changes in lithic reduction patterns are not evident. In this paper, the implications of such observations are contextualized within the general discussion on the behaviour of the South-eastern Pyrenees Neanderthals.     

A mathematical derivation of size spectra in fish populations

Taking into account a predator/prey size ratio in a size-structured population model leads to a partial derivative equation of which we study the properties. By expliciting the structure of the attractor of this equation, it is shown that a simple mechanism, size-based opportunistic predation, can explain the stability in the shape of size spectra observed in various marine ecosystems.     

Between simplicity and complexity: The knapping flexibility on cobbles at the early Neolithic site of Zengpiyan Cave (12–7 ka), Guangxi Zhuang Autonomous Region,southern China

The cobble industry in southern Chinese provinces was for a long time called large and simple “chopper-chopping tool tradition,” which persisted from the Early Pleistocene to the Middle Holocene. This recognition is 50% true and 50% false because it does not reflect the entire archaeological reality. On the one hand, the so-called “chopper-chopping tool” category often characterizes or dominates the lithic assemblages; on the other hand, a “chopper” from site A could be different from another “chopper” in site B. This distinction is important since the typological names lost their validity when conducting comparative studies inter- and intra-sites. The cobble tool industry of the Zengpiyan cave site (Guilin City, Guangxi Zhuang Autonomous Region, China) is an excellent example of this terminological dilemma, which presents some extent of both simplicity and complexity, underestimated in its production strategies. We could also find substantial flexibility between the two ends (simplicity and complexity) during the selection and exploitation of the cobble/pebble blanks. Although chopper-chopping tools are predominant at the site, the variability of their morpho-structures and techno-functional organization indicate that they are not just simple chopper-chopping tools sensu stricto but have their specific characteristics which could not be found in their typological names. In this context, we need to re-evaluate the previously so-called “choppers” in south China with a techno-functional approach before comparing different lithic assemblages. Compared with other contemporary sites, the Zengpiyan technical system is not far from those found in South China and mainland Southeast Asia. For example, it has similarities with the Sonvian phenomenon in northern Vietnam and some other sites in southern China. While very different from the Hoabinhian technocomplex, the Zengpiyan assemblage raises questions about the kinship with other Late Pleistocene lithic facies. Further technological studies on a larger number of sites in these regions are still needed to understand better the prehistoric techno-cultural relationships between the industrial assemblages of southern China and those bordering the Far East.     

Development rate,number of mature oocytes at emergence and adult size ofEncarsia tricolor at constant and variable temperatures

The duration of the development of the aphelinidEncarsia tricolor Föerster (a parasitoid of the aleyrodidTrialeurodes vaporariorum (Westwood), adult size and number of mature oocytes at emergence were determined under constant and variable temperature regimes. Females developed successfully from 14 to 32°C, but a 100% of pupal mortality was observed at 34°C. Males developed successfully from 16 to 28°C and they developed faster than females. Female and male, egg to adult development at constant temperatures ranged from 51.1 (14°C) to 14.3 (28°C) days and from 32.6 (16°C) to 11.8 (28°C) days, respectively. Predictions of the rate of development at variable temperatures were more accurate when made from 2nd and 3rd degree polynomials than from linear regressions. The number of mature oocytes at emergence ranged from 0.1 (30°C) to 2.2 (20°C). FemaleE. tricolor attained the greatest size at 20–24°C. The comparison with literature data shows thatE. tricolor develops faster thanT. vaporariorum at temperatures above 15°C.     

Conduite à tenir devant un enfant de grande taille

The diagnostic approach to tall stature in children is based on collecting birth data (macrosomia), sizes and family puberty, a family history of constitutional or pathological tall stature, search for a delay of development, dysmorphia, disproportion, analysis of the growth velocity (normal or accelerated), general and pubertal assessment, and bone age. When there is psychomotor retardation, a family history of pathological tall stature, or a disproportion in the clinical examination, the genetic causes of tall stature will be mentioned. The most frequent causes are Marfan syndrome and similar, Sotos syndrome, Beckwith–Wiedemann syndrome, Klinefelter syndrome, and MEN2B. These different genetic syndromes with tall stature justify a consultation with the geneticist. When the speed of growth is accelerated, first of all, it evokes puberty and early pseudopuberty, obesity and acromegaly. Finally, when the speed of growth is regular, and the parents are of tall stature, it evokes constitutional tall stature: this is the most frequent diagnosis to retain after having rejected pathological tall statures.     

L’industrie lithique des gisements du Pléistocène inférieur de Barranco León et Fuente Nueva 3 à Orce, Grenade, Espagne

The archaeological localities of Barranco León and Fuente Nueva 3 in Orce, Grenade, in actuality have the oldest lithic artifacts in Europe; they are the oldest evidence of human occupation in the east of Europe. When compared the results from faunal analysis and magnetostratigraphical study, notably through the presence of Allophaiomys lavocati allow for a date of around 1.3 Ma. The raw material used for developing these lithic industries are, basically limestone or siliceous rocks, these raw materials selected were smoothed down in situ. The techniques used are knapping at raised with a hammerstone, and we can find all the different elements of the “chaine opératoire”. Both localities are characterised by the predominance of flakes and debris, cores, and some knapped cobbles sowing mediocre aspect. The technical and typological features of both lithic assemblages have an opportunist character but they are relatively sophisticated too.