Comparison of the proliferative activity of neuroblasts from chick embryo cerebral hemispheres of different ages in culture.

Dissociated cerebral hemisphere cells from 4- to 7-day-old chick embryos were cultured either on a collagen or a polylysine substrate in a serum-containing medium. Neurons were characterized by the demonstration of acetylcholinesterase, the presence of D2/N-CAM glycoprotein and neurofilament proteins. The proliferation of neuronal precursor cells was shown by morphological observations, autoradiographic analysis and measurements of [3H]-thymidine incorporation. Neuronal precursors derived from the 6-day-old embryos showed the highest proliferative activity. Neuroblast proliferation was found to be dependent on the culture substrates (i.e. polylysine or collagen), which yielded either isolated cells or cell aggregates, and the latter favored the mitogenic effect.

A Mixed-method Social Networks Study Design for Research on Transnational Families

This paper advocates the adoption of a mixed-methods research design to describe and analyze ego-centered social networks in transnational family research. Drawing on the experience of the Social Networks Influences on Family Formation project (2004-2005), I show how the combined use of network generators and semistructured interviews (N = 116) produces unique data on family configurations and their impact on life course choices. A mixed-methods network approach presents specific advantages for research on children in transnational families. On the one hand, quantitative analyses are crucial for reconstructing and measuring the potential and actual relational support available to children in a context where kin interactions may be hindered by temporary and prolonged periods of separation. On the other hand, qualitative analyses can address strategies and practices employed by families to maintain relationships across international borders and geographic distance, as well as the implications of those strategies for children's well-being.

Cutaneous benign mixed tumor (chondroid syringoma) of the eyelid: clinical presentation and management.

PURPOSE: To describe the clinical presentation of cutaneous benign mixed tumor of the eyelid and its management options. METHODS: Periocular cases of cutaneous benign mixed tumor were gathered from members of an oculoplastics specialty Internet discussion group. A total of 9 patients are described in this retrospective, interventional case series. The clinical presentation, histopathology, and management of these lesions is reviewed. RESULTS: Patients were typically asymptomatic, presenting with a slowly enlarging, nontender nodule of 2 to 8 years' duration. The lesions ranged from 4 mm to 17 mm in greatest dimension. Four of the lesions were on the eyelid margin, three in the sub-brow area of the upper eyelid, and two in the central lids. All six cases not involving the brow were fixed to the tarsus; one brow lesion was believed to be adherent to the skin. None of the lesions was associated with significant changes of the overlying epidermis, although one lesion showed overlying pigmentation. All patients underwent excisional biopsy for diagnostic or cosmetic reasons. On histopathologic examination, the tumors were biphasic, with an epithelial component exhibiting apocrine or hair follicle differentiation and a myxoid, adipocytic, chondroid, and/or fibrous stroma. The pathologic diagnoses were all consistent with cutaneous benign mixed tumor (chondroid syringoma, pleomorphic adenoma). Follow-up ranged from 2 weeks to 12 months, although several patients failed to keep scheduled follow-up appointments. No clinical recurrences were identified. CONCLUSIONS: Cutaneous benign mixed tumor may occur in the eyelid, and, although uncommon, should be included in the differential diagnosis of firm, nodular eyelid tumors. The histopathologic features are similar to those seen in this tumor type arising in other areas of the body. Preoperative consideration of this diagnostic possibility may allow the surgeon to plan for complete excision, thereby reducing the possibility of recurrence or malignant transformation.

The new culture of electronic publishing

Local conditions in the past often limited opportunities for scholarly exchange. But now these limits are gone and the global workplace has replaced them. It is important to react to these changes. Every academic department must now adopt new methods and rethink processes. Another is the intense national and international debate about open access to scholarly knowledge. The Open Access Initiative shows that a change is taking place in the communication process. This change is also important for service departments within research institutions. Libraries, computer centers and related units have to ask themselves how to react appropriately to the new conditions. What services must be changed or redeveloped, and in what quality and quantity should they be offered? This article focuses on changes in the scholarly publication process. It describes both technological changes and the changes needed in people's attitudes.

Radiation and energy balance of lettuce culture inside a polyethylene greenhouse

The objective of this paper was to describe the radiation and energy balance, during the lettuce (Lactuca sativa, L. cv. Verônica) crop cycle inside a polyethylene greenhouse. The radiation and energy balance was made inside a tunnel greenhouse with polyethylene cover (100 mum) and in an external area, both areas with 35 m². Global, reflected and net radiation, soil heat flux and air temperature (dry and humid) were measured during the crop cycle. A Datalogger, which operated at 1 Hz frequency, storing 5 minutes averages was utilized. The global (K¯) and reflected (K­) radiations showed that the average transmission of global radiation (K¯in / K¯ex) was almost constant, near to 79.59%, while the average ratio of reflected radiation (K­in / K­ex) was 69.21% with 8.47% standard-deviation. The normalized curves of short-wave net radiation, in relation to the global radiation (K*/ K¯), found for both environments, were almost constant at the beginning of cycle; this relation decreased in the final stage of culture. The normalized relation (Rn/ K¯) was bigger in the external area, about 12%, when the green culture covered the soil surface. The long-wave radiation balance average (L*) was bigger outside, about 50%. The energy balance, estimated in terms of vertical fluxes, showed that, for the external area, in average, 83.07% of total net radiation was converted in latent heat evaporation (LE), and 18% in soil heat flux (G), and 9.96% in sensible heat (H), while inside of the greenhouse, 58.71% of total net radiation was converted in LE, 42.68% in H, and 28.79% in G.

Sémiotique, culture et développement psychologique

Ce livre propose une perspective novatrice en psychologie qui intègre la culture à titre constitutif dans son approche du développement. Comment les productions humaines contribuent-elles au développement psychologique ? Au sens fort, comment produisent-elles le psychisme ? Et comment, en les étudiant, en saisir les développements originaux chez les sujets dans leurs contextes de production ? Les recherches présentées dans cet ouvrage portent ainsi sur les dimensions matérielles de la culture dans l'avènement et le fonctionnement du psychisme, en intégrant également le langage et d'autres dimensions idéelles de celle-ci. Les textes de cet ouvrage s'inscrivent dans un dialogue interdisciplinaire, replaçant la psychologie dans le cercle des sciences humaines et sociales, requestionnant de facto son épistémologie et ses méthodes.