3D sub-pixel correlation length imaging.

Quantitative 2D neutron dark-field-imaging with neutron grating interferometry has been used to characterize structures in the size range below the imaging resolution. We present the first 3D quantitative neutron dark-field imaging experiment. We characterize sub-pixel structure sizes below the imaging resolution in tomography by quantitatively analyzing the change in dark-field contrast with varying neutron wavelength. This proof of principle experiment uses a dedicated reference sample with four different solutions of microspheres, each with a different diameter. The result is a 3D tomogram featuring a real space scattering function in each voxel. The presented experiment is expected to mark the path for future material science research through the individual quantification of small-angle scattering structures in each voxel of a volume of a bulk inhomogeneous sample material.

Achromatic Non-Interferometric Single Grating Neutron Dark-Field Imaging.

We demonstrate a simple single grating beam modulation technique, which enables the use of a highly intense neutron beam for differential phase and dark-field contrast imaging and thus spatially resolved structural correlation measurements in full analogy to interferometric methods. In contrast to these interferometric approaches our method is intrinsically achromatic and provides unprecedented flexibility in the choice of experimental parameters. In particular the method enables straight forward application of quantitative dark-field contrast imaging in time-of-flight mode at pulsed neutron sources. Utilizing merely a macroscopic absorption mask unparalleled length scales become accessible. We present results of quantitative dark-field contrast imaging combining microstructural small angle scattering analyses with real space imaging for a variety of materials.

Visualizing the heterogeneous breakdown of a fractal microstructure during compaction by neutron dark-field imaging.

Structural properties of cohesive powders are dominated by their microstructural composition. Powders with a fractal microstructure show particularly interesting properties during compaction where a microstructural transition and a fractal breakdown happen before compaction and force transport. The study of this phenomenon has been challenging due to its long-range effect and the subsequent necessity to characterize these microstructural changes on a macroscopic scale. For the detailed investigation of the complex nature of powder compaction for various densification states along with the heterogeneous breakdown of the fractal microstructure we applied neutron dark-field imaging in combination with a variety of supporting techniques with various spatial resolutions, field-of-views and information depths. We used scanning electron microscopy to image the surface microstructure in a small field-of-view and X-ray tomography to image density variations in 3D with lower spatial resolution. Non-local spin-echo small-angle neutron scattering results are used to evaluate fitting models later used as input parameters for the neutron dark-field imaging data analysis. Finally, neutron dark-field imaging results in combination with supporting measurements using scanning electron microscopy, X-ray tomography and spin-echo small angle scattering allowed us to comprehensively study the heterogeneous transition from a fractal to a homogeneous microstructure of a cohesive powder in a quantitative manner.

A Monte Carlo approach for scattering correction towards quantitative neutron imaging of polycrystals.

The development of neutron imaging from a qualitative inspection tool towards a quantitative technique in materials science has increased the requirements for accuracy significantly. Quantifying the thickness or the density of polycrystalline samples with high accuracy using neutron imaging has two main problems: (i) the scattering from the sample creates artefacts on the image and (ii) there is a lack of specific reference attenuation coefficients. This work presents experimental and simulation results to explain and approach these problems. Firstly, a series of neutron radiography and tomography experiments of iron, copper and vanadium are performed and serve as a reference. These materials were selected because they attenuate neutrons mainly through coherent (Fe and Cu) and incoherent (V) scattering. Secondly, an ad hoc Monte Carlo model was developed, based on beamline, sample and detector parameters, in order to simulate experiments, understand the physics involved and interpret the experimental data. The model, developed in the McStas framework, uses a priori information about the sample geometry and crystalline structure, as well as beamline settings, such as spectrum, geometry and detector type. The validity of the simulations is then verified with experimental results for the two problems that motivated this work: (i) the scattering distribution in transmission imaging and (ii) the calculated attenuation coefficients.

Statistical uncertainty in the dark-field and transmission signal of grating interferometry.

We present a framework to estimate the fundamental statistical uncertainty of grating interferometer experiments based on a Monte-Carlo method. Using the framework, we are able to determine the uncertainty of individual measurements as well as suggesting experimental protocols that minimise the statistical uncertainty for given overall exposure times. The method presented here is valid for both X-rays and neutrons and can be generalised for any modulation measurement.

Subsistence hunting of Cuniculus paca in the middle of the Solimões River, Amazonas, Brazil.

Ungulates, large primates and caviomorfs are cited by Amazonian hunters as preferred species. In this research, paca (Cuniculus paca) hunting was investigated in relation to water levels and the lunar cycle. In eight years of monitoring in the Amanã Sustainable Development Reserve, the killing of 625 pacas was registered in five monitored communities. Paca hunting took place mainly at night and the most commonly used method is "spotlighting". A positive correlation between the number of pacas killed and water level (rs=0.890; p<0.0001) was found. At least 37% of the pacas were hunted when moon illumination level was less than 10%, before moonrise or after moonset. In the Boa Esperança community, capture of paca tended to decrease on nights with high moon illumination (rs= -0.663; p=0.067). At the same time, an expressive catch-per-unity-effort decrease was also observed in this community (r2= -0.881; p<0.001), allowing us to predict unsustainable hunting levels for the next decade. The stock of animals in these areas could be continuously replaced if surrounding areas consisted of continuous forests. However, continuous hunting and deforestation force local hunters to travel longer distances to kill prey such as pacas. The confirmation of the relation between paca habits and lunar illumination and water level, a pattern described by local hunters, demonstrates the potential value of participatory research and the possibility of integrating traditional knowledge into scientific knowledge.

Subsistence hunting of Cuniculus paca in the middle of the Solimões River, Amazonas, Brazil / Caça de subsistência de Cuniculus paca no Médio Solimões, Amazonas, Brasil

Ungulates, large primates and caviomorfs are cited by Amazonian hunters as preferred species. In this research, paca (Cuniculus paca) hunting was investigated in relation to water levels and the lunar cycle. In eight years of monitoring in the Amanã Sustainable Development Reserve, the killing of 625 pacas was registered in five monitored communities. Paca hunting took place mainly at night and the most commonly used method is “spotlighting”. A positive correlation between the number of pacas killed and water level (rs=0.890; p<0.0001) was found. At least 37% of the pacas were hunted when moon illumination level was less than 10%, before moonrise or after moonset. In the Boa Esperança community, capture of paca tended to decrease on nights with high moon illumination (rs= −0.663; p=0.067). At the same time, an expressive catch-per-unity-effort decrease was also observed in this community (r2= −0.881; p<0.001), allowing us to predict unsustainable hunting levels for the next decade. The stock of animals in these areas could be continuously replaced if surrounding areas consisted of continuous forests. However, continuous hunting and deforestation force local hunters to travel longer distances to kill prey such as pacas. The confirmation of the relation between paca habits and lunar illumination and water level, a pattern described by local hunters, demonstrates the potential value of participatory research and the possibility of integrating traditional knowledge into scientific knowledge.

Ungulados, primatas de grande porte e caviomorfos são citados por caçadores amazônicos como espécies preferenciais. Neste trabalho, a caça de paca (Cuniculus paca) foi investigada em relação ao nível d'água e ao ciclo lunar. O abate de 625 pacas foi registrado em oito anos de monitoramento em cinco comunidades da Reserva de Desenvolvimento Sustentável Amanã. A caça de paca ocorre principalmente à noite e o método mais utilizado é a “focagem”. Encontrou-se uma correlação positiva entre o número de pacas abatidas e o nível d'água (rs=0.890; p<0.0001). Pelo menos 37% dos indivíduos foram abatidos quando o nível de iluminação lunar era menor do que 10%, antes do nascer da lua ou após seu ocaso. Na comunidade da Boa Esperança, a captura de paca tendeu ao decrescimento em noites com altos níveis de iluminação lunar (rs=−0.663; p=0.067). Ao mesmo tempo, uma expressiva redução da captura por unidade de esforço foi observada nessa comunidade (r2=−0.881; p<0.001), permitindo-nos prever níveis de caça insustentáveis para a próxima década. Frente a extensas áreas contínuas de floresta, o estoque de animais nas áreas de caça poderia ser continuamente substituído, mas os efeitos combinados de caça constante e desmatamento forçam caçadores locais a se locomoverem por longas distâncias para abater presas como as pacas. A confirmação dos padrões descritos por moradores locais sobre a relação entre pacas e os níveis de iluminação lunar e de água demonstra o potencial de pesquisa participativa e a possibilidade de integração entre os conhecimentos tradicionais e científicos.

New data on the ecology and geographic distribution of Saguinus inustus Schwarz, 1951 (Primates, Callitrichidae).

Saguinus inustus (Schwarz, 1951) is one of the neotropical primates least studied. The distribution of the species ranges from the north of the Solimões River, between the Negro and Japurá Rivers in Brazil, and Guayabero-Guaviare Rivers in Colombia. Nevertheless, due to the low number of specimens collected from the lower Japurá and lower Negro Rivers areas, the geographic distribution is so far poorly delineated. In this study, field data was composed of sightings and the collection of specimens during a survey of mammal diversity in the Amana Sustainable Development Reserve (ASDR). For this survey, two 40-day expeditions were carried out in 2004. The first one occurred during the flooded season in June and July, and the second was during the peak of the dry season in October. Direct sightings were made through hiking along transects, navigation along water channels with a 30-hp speedboat, and gliding along flooded trails in the forest. New records of S. inustus were made in 11 different localities in ASDR. The study has confirmed the presence of the species in the Amanã area, carrying out the first records of the species in flooded forest habitats.

New data on the ecology and geographic distribution of Saguinus inustus Schwarz, 1951 (Primates, Callitrichidae) / Novos dados sobre a ecologia e distribuição geográfica de Saguinus inustus Schwarz, 1951 (Primates, Callitrichidae)

Saguinus inustus (Schwarz, 1951) is one of the neotropical primates least studied. The distribution of the species ranges from the north of the Solimões River, between the Negro and Japurá Rivers in Brazil, and Guayabero-Guaviare Rivers in Colombia. Nevertheless, due to the low number of specimens collected from the lower Japurá and lower Negro Rivers areas, the geographic distribution is so far poorly delineated. In this study, field data was composed of sightings and the collection of specimens during a survey of mammal diversity in the Amana Sustainable Development Reserve (ASDR). For this survey, two 40-day expeditions were carried out in 2004. The first one occurred during the flooded season in June and July, and the second was during the peak of the dry season in October. Direct sightings were made through hiking along transects, navigation along water channels with a 30-hp speedboat, and gliding along flooded trails in the forest. New records of S. inustus were made in 11 different localities in ASDR. The study has confirmed the presence of the species in the Amanã area, carrying out the first records of the species in flooded forest habitats.

Saguinus inustus (Schwarz, 1951) é um dos primatas neotropicais menos estudados. No Brasil, a espécie ocorre ao norte do Rio Amazonas entre os Rios Negro e Japurá (Caquetá), e Guayabero-Guaviare na Colômbia. No entanto, devido ao pequeno número de espécimes coletados entre o baixo Japurá e o baixo Negro a distribuição geográfica é mal delineada. No presente estudo, os dados de campo são compostos por observações e coletas realizadas durante o levantamento da diversidade de mamíferos da Reserva de Desenvolvimento Sustentável Amanã (RDSA). Para este levantamento, duas expedições de 40 dias foram realizadas em 2004. A primeira ocorreu durante a estação da cheia em junho e julho, e a segunda durante o pico da estação seca em outubro. Observações diretas foram feitas através de deslocamentos a pé em transecções, de lancha 30 hp ao longo de cursos d'água, e de canoas durante a cheia na área de várzea. Novos registros de S. inustus foram realizados em 11 diferentes localidades na RDSA. Este estudo confirmou a presença da espécie em Amanã, realizando os primeiros registros da espécie em florestas alagadas.