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Mendes Barros K.R.,Federal Rural University of Amazonia | De Lima H.V.,Federal Rural University of Amazonia | Rodrigues S.,Federal Rural University of Amazonia | Kern D.C.,Museu Paraense Emilio Goeldi MPEG
Revista Ciencia Agronomica | Year: 2016

Archaeological dark earth (TPA) are areas of soil with an anthropogenic A horizon of high organic carbon content, a dark colour and high fertility. Little is known about the physical characteristics of these soils, especially with respect to structure and pore space. The hypothesis of this study is that the distribution of structural and textural pore space in TPA soils is similar, regardless of texture. The aim therefore was to evaluate the pore space of TPA soils of different textural classes by employing a double-exponential model. Four archaeological sites of varying grain size were sampled in the towns of Melgaço and Igarapé-Açu, in the State of Pará, Brazil. Disturbed and undisturbed soil samples were collected at a depth of 0.10 m. Soil texture ranged from sandy loam to sandy clay loam. The double-exponential equation made it possible to differentiate between textural and structural pores of the TPA sites. Despite the variation in texture, the TPA sites did not differ as to textural porosity, with only site 1 (S1) showing greater structural pore space. The ratio of textural to structural pores did not influence soil density, however, the textural pores were positively related to the organic matter content of the soil.

Gil A.S.B.,Museu Paraense Emilio Goeldi MPEG | Bittrich V.,R. Mario de Nucci | do Amaral M.C.E.,University of Campinas
Phytotaxa | Year: 2014

Neomarica eburnea and N. floscella, two new species of Iridaceae (Trimezieae) from Bahia state (Northeastern Brazil) are here described. Illustrations, diagnostic comparisons with morphologically similar species and an identification key for the species of the genus occurring in Bahia state are presented. © 2014 Magnolia Press.

De Avila Junior R.S.,Federal University of Pampa | Urdampilleta J.,National University of Costa Rica | Gil A.B.,Museu Paraense Emilio Goeldi MPEG
Rodriguesia | Year: 2015

The meiotic behaviour of Sisyrinchium commutatum (Iridaceae) was studied and associated to the pollen quality observed in a southeastern population in Brazil. For the first time, the chromosome number is reported for this species (2n = 36). Some traits of floral biology were recorded and secondary pollen presentation as well as the absence of autonomous self-fertilization and apomixy were observed. The results of this study confirm the abnormalities in the meiosis process breaking the pollen grain formation with consequences to reproductive success in the studied population.

Meyer J.,Museu Paraense Emilio Goeldi MPEG | Dentel L.,Federal University of Para | Meunier F.,French National Center for Scientific Research
PLoS ONE | Year: 2013

In the real world, human speech recognition nearly always involves listening in background noise. The impact of such noise on speech signals and on intelligibility performance increases with the separation of the listener from the speaker. The present behavioral experiment provides an overview of the effects of such acoustic disturbances on speech perception in conditions approaching ecologically valid contexts. We analysed the intelligibility loss in spoken word lists with increasing listener-to-speaker distance in a typical low-level natural background noise. The noise was combined with the simple spherical amplitude attenuation due to distance, basically changing the signal-to-noise ratio (SNR). Therefore, our study draws attention to some of the most basic environmental constraints that have pervaded spoken communication throughout human history. We evaluated the ability of native French participants to recognize French monosyllabic words (spoken at 65.3 dB(A), reference at 1 meter) at distances between 11 to 33 meters, which corresponded to the SNRs most revealing of the progressive effect of the selected natural noise (-8.8 dB to -18.4 dB). Our results showed that in such conditions, identity of vowels is mostly preserved, with the striking peculiarity of the absence of confusion in vowels. The results also confirmed the functional role of consonants during lexical identification. The extensive analysis of recognition scores, confusion patterns and associated acoustic cues revealed that sonorant, sibilant and burst properties were the most important parameters influencing phoneme recognition. . Altogether these analyses allowed us to extract a resistance scale from consonant recognition scores. We also identified specific perceptual consonant confusion groups depending of the place in the words (onset vs. coda). Finally our data suggested that listeners may access some acoustic cues of the CV transition, opening interesting perspectives for future studies. © 2013 Meyer et al.

Absy M.L.,National Institute of Amazonian Research | Cleef A.M.,University of Amsterdam | Dapolito C.,National Institute of Amazonian Research | Dapolito C.,University of Birmingham | Da Silva M.F.F.,Museu Paraense Emilio Goeldi MPEG
Palynology | Year: 2014

Pollen rain studies in Amazonia are scarce but of utmost importance to support interpretations of pollen records. We have investigated modern surface pollen spectra and vegetation in an Amazon location, Carajás, Brazil, where open and woody types of vegetation, swamps and lakes develop under rock outcrops. Both plant inventories of different savanna types along with bryophytic surface samples were analysed with ecological ordination. The results point to taxa that can be used in the differentiation of dry and flooded systems within the savannas studied. Dry savannas, either open or wooded, are indicated by the herbs Cuphea, Asteraceae, Borreria, Caryophyllaceae and Polygonaceae, and by woody taxa such as Myrtaceae, Byrsonima, Sapotaceae, Neea and Rubiaceae. Flooded savannas (swamps) and lakes are indicated by herbs like Sagittaria, Montrichardia, Nymphaea, Cyperaceae and Mimosa and palms. Poaceae was found to have a bipolar signature, and using it as an indicator should be done with caution. © 2014 © 2014 AASP - The Palynological Society.

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