Synchrony of hand-foot coupled movements: is it attained by mutual feedback entrainment or by independent linkage of each limb to a common rhythm generator?

BACKGROUND: Synchrony of coupled oscillations of ipsilateral hand and foot may be achieved by controlling the interlimb phase difference through a crossed kinaesthetic feedback between the two limbs, or by an independent linkage of each limb cycle to a common clock signal. These alternative models may be experimentally challenged by comparing the behaviour of the two limbs when they oscillate following an external time giver, either alone or coupled together. RESULTS: Ten subjects oscillated their right hand and foot both alone and coupled (iso- or antidirectionally), paced by a metronome. Wrist and ankle angular position and Electromyograms (EMG) from the respective flexor and extensor muscles were recorded. Three phase delays were measured: i) the clk-mov delay, between the clock (metronome beat) and the oscillation peak; ii) the neur (neural) delay, between the clock and the motoneurone excitatory input, as inferred from the EMG onset; and iii) the mech (mechanical) delay between the EMG onset and the corresponding point of the limb oscillation. During uncoupled oscillations (0.4 Hz to 3.0 Hz), the mech delay increased from -7° to -111° (hand) and from -4° to -83° (foot). In contrast, the clk-mov delay remained constant and close to zero in either limb since a progressive advance of the motoneurone activation on the pacing beat (neur advance) compensated for the increasing mech delay. Adding an inertial load to either extremity induced a frequency dependent increase of the limb mechanical delay that could not be completely compensated by the increase of the neural phase advance, resulting in a frequency dependent increment of clk-mov delay of the hampered limb. When limb oscillations were iso- or antidirectionally coupled, either in the loaded or unloaded condition, the three delays did not significantly change with respect to values measured when limbs were moved separately. CONCLUSION: The absence of any significant effect of limb coupling on the measured delays suggests that during hand-foot oscillations, both iso- and antidirectionally coupled, each limb is synchronised to the common rhythm generator by a "private" position control, with no need for a crossed feedback interaction between limbs

Marine-friendly antifouling coating based on the use of a fatty acid derivative as a pigment

This study was devoted to examining the application of copper dodecanoate as a non-contaminant antifouling pigment due to its low copper content and fatty acid nature. For this purpose, antifouling paints with mono-component epoxy resin and rosin matrixes were formulated, and their antifouling efficiency was evaluated. Before its incorporation into the different formulations, the synthesized pigment was characterized. Immersion tests in a marine environment were carried out for 12 months to evaluate the antifouling efficiency of the developed paints; the results were compared with those from a commercial paint. The antifouling efficiency of the new epoxy formulation was found to be considerably higher than that of the rosin formulation and very similar to that of the commercial paint. Most importantly, the release of copper from the epoxy paint formulated with copper dodecanoate was 73.5% lower than that of the commercial paint, suggesting prolonged activity of the developed paint.Peer ReviewedPostprint (published version

Revisão das espécies do grupo de Bufo crucifer, com descrições de duas espécies relacionadas (Amphibia, Anura, Bufonidae)

The Bufo crucifer species group is revised on the basis of external morphological and morphometrical characteristics, evidencing variation in size, shape of the parotoid gland, width of the head, cranial crests, and presence or absence of yellow spots near the cloaca and hind limbs. Five species are recognized: B. crucifer Wied-Neuwied, 1821, B. ornatus Spix, 1824 (revalidated), B. henseli A.Lutz, 1934 (revalidated), B. abei sp.nov., and B. pombali sp.nov. The geographic distribution of the species is associated with the Atlantic Rain Forest and adjacent areas: B. crucifer occurs from the State of Ceará to southern State of Espírito Santo and northeastern State of Minas Gerais; B. ornatus is distributed from southern State of Espírito Santo, through the states of Rio de Janeiro and São Paulo to northern State of Paraná, and possibly in northeastern Argentina, in the provinces Misiones and Corrientes; B. henseli is found from southern State of Santa Catarina to the coast of the State of Rio Grande do Sul; B. abei sp.nov., described from Córrego Grande, Municipality of Florianópolis, State of Santa Catarina, is distributed from the State of Paraná to southern State of Santa Catarina and areas of the northern State of Rio Grande do Sul; and B. pombali sp.nov., described from the Reserva Biológica de Peti, Municipality of São Gonçalo do Rio Abaixo, State of Minas Gerais, occurs in transitional areas between the Atlantic Rain Forest and the “cerrados” in the State of Minas Gerais. Additionally, Bufo crucifer var. pfrimeri Miranda-Ribeiro, 1926, currently in the synonymy of B. crucifer, is transfered to the synonymy of Bufo guttatus Schneider, 1799. Bufo levicristatus Boettger, 1885 is considered a species inquirenda and removed from the synonymy of any species included in the B. crucifer group. Bufo spixii Fitzinger, 1826 is transfered from the synonymy of Bufo margaritifer (Laurenti, 1768) to the synonymy of Bufo ornatus Spix, 1824.O grupo de Bufo crucifer é revisado com base em caracteres morfológicos externos e morfométricos, evidenciando variação em tamanho, forma das glândulas parotóides, largura da cabeça, cristas cefálicas e presença ou ausência de manchas amarelas próximo à cloaca e nas pernas. Cinco espécies são reconhecidas: Bufo crucifer Wied-Neuwied, 1821, B. ornatus Spix, 1824 (revalidada), B. henseli A.Lutz, 1924 (revalidada), B. abei sp.nov. e B. pombali sp.nov. A distribuição geográfica das espécies é associada à Floresta Atlântica e regiões adjacentes: B. crucifer ocorre do Estado do Ceará ao sul do Estado do Espírito Santo e nordeste do Estado de Minas Gerais; B. ornatus ocorre do sul do Estado do Espírito Santo, através dos Estados do Rio de Janeiro e São Paulo até o norte do Estado do Paraná e possivelmente no nordeste da Argentina, nas Províncias Misiones e Corrientes; B. henseli é encontrada do sul do Estado de Santa Catarina até a região costeira do Estado do Rio Grande do Sul; B. abei sp.nov., descrita de Córrego Grande, Município de Florianópolis, Estado de Santa Catarina, está distribuída do Estado do Paraná até o sul do Estado de Santa Catarina e áreas do norte do Estado do Rio Grande do Sul; B. pombali sp.nov., descrita da Reserva Biológica de Peti, Município de São Gonçalo do Rio Abaixo, Estado de Minas Gerais, ocorre nas áreas de transição entre a Floresta Atlântica e os cerrados no Estado de Minas Gerais. Adicionalmente, Bufo crucifer var. pfrimeri Miranda-Ribeiro, 1926, atualmente incluída na sinonimia de B. crucifer, é transferida para a sinonimia de Bufo guttatus Schneider, 1799. Bufo levicristatus Boettger, 1885 é considerada species inquirenda e retirada da sinonimia de qualquer das espécies incluídas no grupo de B. crucifer. Bufo spixii Fitzinger, 1826 é transferida da sinonimia de Bufo margaritifer (Laurenti, 1768) para a sinonimia de Bufo ornatus Spix, 1824

study of two alternative cooling systems of a mold insert used in die casting process of light alloy components

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Herbário das pastagens naturais: 41 anos de história.

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