Koffka, Köhler, and the "crisis" in psychology

This paper examines the claims of the Gestalt psychologists that there was a crisis in experimental psychology ca. 1900, which arose because the prevailing sensory atomism excluded meaning from among psychological phenomena. The Gestaltists claim that a primary motivation of their movement was to show, against the speculative psychologists and philosophers and Verstehen historians, that natural scientific psychology can handle meaning. Purportedly, they revealed this motivation in their initial German-language presentations but in English emphasized their scientific accomplishments for an American audience. The paper finds that: there was a recognized crisis in the new experimental psychology ca. 1900 pertaining especially to sensory atomism; that the Gestaltists responded to the crisis with new experimental findings and theoretical concepts (Gestalten) that challenged atomism; in both languages, they raised problems of meaning and discussed the contest with speculative psychology and philosophy only after presenting their scientific case; that they introduced phenomenological observations on meaning and perceptual organization into their psychology but did not develop a theory of meaning or solve philosophical problems; that they argued "philosophically," that is, using abstract, conceptual arguments; and that this aspect of their cognitive style was not received well by some prominent members of their American audience.     

Mycorrhizal perennials of the "matorral xerófilo" and the "selva baja caducifolia" communities in the semiarid Tehuacán-Cuicatlán Valley,Mexico

We investigated the mycorrhizal status of perennial xeric plant species occurring in the "matorral xerófilo" (arid tropical scrub) and the ecotone of the "selva baja caducifolia" (tropical deciduous forest) communities in the semiarid valley of Tehuacán-Cuicatlán, south-central Mexico. The perennial species examined are dominant/codominant elements within the "matorral xerófilo" and the "selva baja caducifolia", both endangered communities in the Biosphere Reserve Tehuacán-Cuicatlán Valley. Of the 50 sampled species, 45 were mycorrhizal. To our knowledge, we report arbuscular mycorrhizae (AM) for the first time in 37 species, of which 21 are endemic to Mexico and nine are endemic to the Valley. We also report AM for the first time in three genera, Buddleja, Hechtia and Zornia, and in one plant family, Buddlejaceae. Beaucarnea gracilis, a threatened species, and Mimosa purpusii, a potentially rare species, are both mycorrhizal. This is the first study of the mycorrhizal status of plant species within the Valley.     

Nipping the Cambrian "explosion" in the bud?

In recent years, two schools of thought have emerged with regard to the Cambrian "explosion". One argues that it was very quick, with phyla tumbling into existence in a virtual geological instant. The other view has a more relaxed temporal perspective. It looks to slow aeons of cryptic metazoan history, which led to a final breakthrough in the Cambrian, not in evolution but of fossilization potential. Yet both views have serious difficulties. Now, in a recent issue of Biological Reviews, Graham Budd and S?ren Jensen(1) argue for a third way. In an intriguing blend of functional morphology, the fossil record and cladistic thinking, they suggest that the assembly of metazoan bodyplans took place in a surprisingly straightforward manner.     

Molluscicide activity of the "avelós" plant (Euphorbia tirucalli, L.) on Biomphalaria glabrata, the mollusc vector of schistosomiasis

An aqueous solution of the latex of Euphorbia tirucalli collected at sites receiving large amounts of sunlight showed molluscicide action on Biomphalaria glabrata, with LD50 obtained at the concentration of 28,0 ppm and LD90 at the concentration of 85,0 ppm. The toxicity of the product for fish was similar to that of Bayluscide and of copper sulfate used for comparison. However, the wide distribution of the plant, its easy propagation and the simple procedure for extraction of the active substance, which is biodegradable, favor "avelós" as a promising agent in the control of schistosomiasis.     

Pancreatic endocrinogenesis revisited:"I have all the answers,who has the questions?"

The endocrine pancreas is composed of islets of Langerhans that are scattered throughout the gland and contain multiple hormone-producing cell types(a,β,δ,PP an...     

Will the "new biology" affect the future of histopathology?

The technologies used in histopathology are changing as a consequence of the current revolutionary progress in several areas of biology. It is likely that general cancer management will improve because of the impact of molecular techniques and immunohistochemistry on tumor diagnosis and classification and on the determination of prognosis and response to therapy. Moreover, as therapies are starting to be modelled after the distinctive molecular characteristics of a specific tumor, the availability of molecular tests to all patients will become a matter of great importance.     

Was the "ABC" approach (abstinence, being faithful, using condoms) responsible for Uganda's decline in HIV?

BACKGROUND TO THE DEBATE: Uganda is one of the few African countries where rates of HIV infection have fallen, from about 15 percent in the early 1990s to about five percent in 2001. At the end of 2005, UNAIDS estimated that 6.7 percent of adults were infected with the virus. The reasons behind Uganda's success have been intensely studied in the hope that other countries can emulate the strategies that worked. Some researchers credit the success to the Ugandan government's promotion of "ABC behaviors"--particularly abstinence and fidelity. Uganda receives funds from the United States President's Emergency Plan for AIDS Relief, which promotes the ABC approach with a focus on abstinence-driven public health campaigns. Other researchers question whether the ABC approach was really responsible for the decline in HIV infection. Critics of the ABC approach also argue that by emphasizing abstinence over condom use, the approach leaves women at risk of infection, because in many parts of the world women are not empowered to insist on abstinence or fidelity.     

Is the "nonspecific" thalamus still "nonspecific"?

The classical concept of "nonspecific" thalamus, as distinguished from the principal thalamic nuclei (i.e. the primary sensory, motor and limbic relays) is here briefly revisited in the light of anatomical investigations performed in the last decades, and primarily those based on tract tracing techniques. Altogether these data pointed out that the so-called "nonspecific" thalamus is composed by a heterogeneous collection of nuclear masses, which display not only species differences, but also marked internuclear variations in their cytological and neurochemical features, connections, areal and laminar distribution upon the cortex, and functional properties. Thus, the "nonspecific" thalamus exerts a modulatory role on cortical activity, chiefly regulated at the intrathalamic level by the interplay between the thalamic reticular nucleus and the interneurons and projection neurons of the dorsal thalamus. However, each of the components that have been traditionally considered as "nonspecific" also subserves selective roles in the transfer of different kinds of information from the thalamus to the cerebral cortex and basal ganglia.     

Phytochemicals: the good, the bad and the ugly?

Phytochemicals are constitutive metabolites that enable plants to overcome temporary or continuous threats integral to their environment, while also controlling essential functions of growth and reproduction. All of these roles are generally advantageous to the producing organisms but the inherent biological activity of such constituents often causes dramatic adverse consequences in other organisms that may be exposed to them. Nevertheless, such effects may be the essential indicator of desirable properties, such as therapeutic potential, especially when the mechanism of bioactivity can be delineated. Careful observation of cause and effect, followed by a coordinated approach to identify the responsible entities, has proved extremely fruitful in discovering roles for phytochemical constituents. The process is illustrated by selected examples of plants poisonous to animals and include the steroidal alkaloid toxin of Veratrum californicum (Western false hellebore), piperidine alkaloids of Lupinus species (lupines), and polyhydroxy indolizidine, pyrrolizidine and nortropane alkaloids of Astragalus and Oxytropis species (locoweeds), Castanospermum australe (Moreton Bay chestnut) and Ipomoea species (morning glories).     

Seasonal evaluation of mammal species richness and abundance in the "Mário Viana" municipal reserve, Mato Grosso, Brasil

We evaluated seasonal species presence and richness, and abundance of medium and large sized mammalian terrestrial fauna in the "Mário Viana" Municipal Biological Reserve, Nova Xavantina, Mato Grosso, Brazil. During 2001, two monthly visits were made to an established transect, 2,820 m in length. Records of 22 mammal species were obtained and individual footprint sequences quantified for seasonal calculation of species richness and relative abundance index (x footprints/km traveled). All 22 species occurred during the rainy season, but only 18 during the dry season. Pseudalopex vetulus (Lund, 1842) (hoary fox), Eira barbara (Linnaeus, 1758) (tayra), Puma concolor (Linnaeus, 1771) (cougar) and Hydrochaeris hydrochaeris (Linnaeus, 1766) (capybara) were only registered during the rainy season. The species diversity estimated using the Jackknife procedure in the dry season (19.83, CI = 2.73) was smaller than in the rainy season (25.67, CI = 3.43). Among the 18 species common in the two seasons, only four presented significantly different abundance indexes: Dasypus novemcinctus Linnaeus, 1758 (nine-banded armadillo), Euphractus sexcinctus (Linnaeus, 1758) (six-banded armadillo), Dasyprocta azarae Lichtenstein, 1823 (Azara's Agouti) and Tapirus terrestris (Linnaeus, 1758) (tapir). On the other hand, Priodontes maximus (Kerr, 1792) (giant armadillo) and Leopardus pardalis (Linnaeus, 1758) (ocelot) had identical abundance index over the two seasons. Distribution of species abundance in the sampled area followed the expected pattern for communities in equilibrium, especially in the rainy season, suggesting that the environment still maintains good characteristics for mammal conservation. The present study shows that the reserve, although only 470 ha in size, plays an important role for conservation of mastofauna of the area as a refuge in an environment full of anthropic influence (mainly cattle breeding in exotic pasture).     

Jiuzhaigou, the Picturesque Valley

Jiuzhaigou covers an area of 720 square kilometers, with an outer-ring protect zone of 600 square kilometers, among which a great majority part is covered with forest. The main gully, more than 50 kilometers long, consists of Shuzheng, Rize arid Zechawa three gullies, forming a shape of "Y". At the end of Zechawa gully lies Changhai (the lake is called "haizi" by the local people) with an eleva-     

Tau phosphorylation, tangles, and neurodegeneration: the chicken or the egg?

Pathological aggregation of the microtubule-associated protein tau is a common feature of many neurodegenerative diseases. Although tau aggregation is associated with abnormal tau phosphorylation, the role of phosphorylation in the initiation of neurodegeneration has been unclear. Now, several animal models and data from human patients provide converging evidence that aberrant tau phosphorylation can cause a neurodegenerative phenotype similar to that seen in human neurodegenerative diseases.