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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
661

Factors influencing the mobility of Red Palm Weevil Rhynchophorus ferrugineus (Coleoptera: Dryophthoridae) adults

Ávalos Masó, Juan Antonio 07 January 2016 (has links)
Tesis por compendio / [EN] The management of Rhynchophorus ferrugineus (Coleoptera: Dryophthoridae), the worst threat for palm trees worldwide, consists in several preventive and curative techniques, but because of its low efficacy the insect still causes major economic and landscape losses. In order to define aspects that have facilitated its rapid dispersal and contribute to improving its management, the effects of vision and flight, which influence the mobility of R. ferrugineus, have been analysed. The chromatic preference of R. ferrugineus has been studied by analysing their captures in coloured bucket traps. Black traps capture the highest number of insects compared with the other colours studied, both when they contain olfactory attractants, as when these compounds are not used, demonstrating that colour by itself is a crucial attraction factor. Moreover, the spectral reflectance of studied colours and of some P. canariensis tissues has been analysed. The wavelength spectrum of black shows great similarity to that of fibres of P. canariensis, so this may be the reason why R. ferrugineus prefers this colour. Regarding sex ratio of the insect in traps, female captures are significantly greater in those baited with olfactory attractants. However, a higher number of female captures does not always occur when these compounds are not used. On the other hand, the study of sex ratio in natural populations of the insect demonstrates that the proportion is one female per male. Therefore, the greater number of captures of females in commercial traps is due exclusively to their greater attraction towards the olfactory attractants used. Another of the analysed aspects has been the flight potential of R. ferrugineus under laboratory conditions. In order to know more about the mobility of this insect, different parameters have been studied using a computer-monitored flight mill. The selected parameters used to define the R. ferrugineus flight potential have been the number of flights, total distance flown, longest single flight, flight duration, and average and maximum speed. Moreover, the influence of sex, body size, and age of the adults on the aforementioned parameters has been examined. R. ferrugineus sex does not have a significant effect on the compared flight parameters. The body size in females is significantly greater, but this does not influence their flight potential. A higher percentage of flight is observed for adults with an age range of 8-23 days old, compared to the 1-7 day old adults. However, age does not significantly influence their flight potential. By analysing the longest single flight undertaken by each adult, up to 63% of the insects can be classified as short-distance flyers (<500m), 27.3% as medium-distance flyers (500-5000m), and >9% as long-distance flyers (>5000m). Finally, the flight behaviour and dispersal of R. ferrugineus have been analysed under field conditions using the mark-release-recapture method. This test focused on detecting the influence of different factors, such as sex, temperature, relative humidity, and solar radiation, in the take-off and dispersal of the adult insects. Take-off probability of R. ferrugineus adults is significantly greater in males Moreover, this probability increases when temperature and solar radiation rise. Concerning the insect dispersal by flying, the number of recaptures is influenced by temperature, increasing significantly when this factor increases. Likewise, dispersal distances also increase significantly as temperatures rise. The insect tends to fly distances <500m (77.1% of recaptured adults), following the same tendency observed in studies performed using the flight mill. However, R. ferrugineus is able to travel up to 7km, being recorded under laboratory conditions a potential flight up to 20km. To conclude, dispersal time of the adults is very short (more than 90% of the adults were recaptured during the first 7 days), being significantly lower when relative humidity increases. / [ES] El manejo de Rhynchophorus ferrugineus (Coleoptera: Dryophthoridae), una de las peores amenazas para las palmeras en el mundo, se lleva a cabo mediante la aplicación de diversas técnicas de prevención y control, pero debido a la baja eficacia de éstas la plaga continúa causando importantes pérdidas económicas y paisajísticas. Para definir los aspectos que han intervenido en su dispersión y contribuir a mejorar su manejo, se ha analizado el efecto de la visión y el vuelo en la movilidad de los adultos de R. ferrugineus. Se ha estudiado la preferencia cromática mediante el análisis de sus capturas en trampas cubo coloreadas. Las trampas negras capturan el mayor nº de insectos en comparación con el resto de colores estudiados, tanto cuando contienen atrayentes olfativos como cuando no los contienen, demostrando que el color por sí mismo es un factor importante de atracción. Además, se ha analizado el espectro de longitud de onda de los colores estudiados y de diversos tejidos de P. canariensis. El espectro del color negro muestra gran similitud con el de las fibras de P. canariensis, es por esto por lo que R. ferrugineus podría presentar esta preferencia. En relación a la proporción de sexos en trampas que contienen atrayentes olfativos, las capturas de hembras son significativamente más elevadas. En cambio, sin éstos no siempre se produce un mayor nº de capturas de este sexo. Por otro lado, el estudio de la proporción de sexos en poblaciones naturales muestra una ratio de una hembra por macho. Por tanto, las mayores capturas de hembras en trampas se deben a una mayor atracción de éstas hacia los atrayentes olfativos. Otro aspecto estudiado ha sido el potencial de vuelo de R. ferrugineus bajo condiciones de laboratorio. Con la finalidad de conocer la movilidad de este insecto se han analizado diversos parámetros mediante la utilización de un molinillo de vuelo computerizado. Los parámetros estudiados han sido: nº vuelos, distancia total volada, vuelo más largo, duración del vuelo y velocidades media y máxima. Además, se ha analizado como influye el sexo, el tamaño del cuerpo y la edad de los adultos en dichos parámetros de vuelo. El sexo de R. ferrugineus no muestra un efecto significativo sobre los parámetros de vuelo comparados. El tamaño del cuerpo de las hembras es significativamente mayor, pero no influye estadísticamente en su potencial de vuelo. En adultos con edades de entre 8-23 días se observa un mayor porcentaje de vuelo que en aquellos con 1-7 días de edad. En cambio, la edad no influye significativamente sobre su potencial de vuelo. Al analizar el vuelo más largo, obtenemos que >63% de los insectos se clasifican como voladores de corta distancia (<500m), el 27.3% de media distancia (500-5000m), y >9% de larga distancia (>5000m). Finalmente, se ha analizado en campo el comportamiento de vuelo y dispersión de R. ferrugineus mediante la técnica de marcaje-suelta-recaptura. Este ensayo ha permitido estudiar la influencia del sexo, la temperatura (Tª), la humedad relativa y la radiación solar, en el despegue y dispersión de los adultos. La probabilidad de despegue de R. ferrugineus es significativamente mayor en machos. Además, esta probabilidad se incrementa cuando la Tª y la radiación solar aumentan. Respecto a la dispersión del insecto mediante el vuelo, el nº de recapturas se ve influenciado por la Tª, aumentando significativamente cuando ésta se incrementa. De la misma manera, las distancias de dispersión también se incrementan significativamente a media que lo hace la Tª. El insecto tiende a volar distancias <500m (77.1% de los adultos recapturados), siguiendo la misma tendencia observada en laboratorio. No obstante, R. ferrugineus es capaz de recorrer hasta 7km, llegando a registrarse vuelos potenciales en laboratorio de hasta 20km. Por último, el tiempo de dispersión de los adultos es muy corto (>90% se recapturaron en los 7 primeros días), reduciéndose / [CA] El maneig de Rhynchophorus ferrugineus (Coleoptera: Dryophthoridae), una de les pitjors amenaces per a les palmeres en tot el món, es porta a terme mitjançant l'aplicació de diverses tècniques de prevenció i control, però degut a la baixa eficàcia d'aquestes l'insecte continua causant importants pèrdues econòmiques i paisatgístiques. Per a definir els aspectes que han intervingut en la seua dispersió i contribuir a la millora del seu maneig, s'ha analitzat l'efecte que tenen la visió i el vol en la mobilitat dels adults de R. ferrugineus. S'ha estudiat la preferència cromàtica mitjançant l'anàlisi de les seues captures en trampes poal acolorides. Les trampes negres capturen el major nombre d'insectes en comparació amb la resta de colors estudiats, tant quan contenen atraients olfactius com quan no els contenen, demostrant que el color per ell mateix és un factor important d'atracció. A més, s'ha analitzat l'espectre de longitud d'ona dels colors estudiats i de diversos teixits de P. canariensis. L'espectre del color negre mostra gran similitud amb el de les fibres de P. canariensis, és per açò pel que R. ferrugineus podria presentar aquesta preferència. En relació a la proporció de sexes a les trampes que contenen atraients olfactius, les captures de femelles són significativament més elevades. En canvi, sense aquests no sempre es produeix un major nombre de captures d'aquest sexe. Per altra banda, l'estudi de la proporció de sexes en poblacions naturals demostra que la ràtio és d'una femella per mascle. Per tant, les majors captures de femelles en trampes es deuen a una major atracció d'aquestes cap als atraients olfactius utilitzats. Altre aspecte estudiat ha sigut el potencial de vol de R. ferrugineus sota condicions de laboratori. Amb la finalitat de conèixer la mobilitat d'aquest insecte s'han analitzat diversos paràmetres mitjançant la utilització d'un molinet de vol computeritzat. Els paràmetres estudiats han sigut: nombre de vols, distància total volada, vol més llarg, duració del vol i velocitats mitjana i màxima dels vols. A més, s'ha analitzat com influeixen el sexe, el tamany del cos i l'edat dels adults en dits paràmetres de vol. El sexe de R. ferrugineus no mostra un efecte significatiu sobre els paràmetres de vol comparats. El tamany del cos de les femelles és significativament major, però no influeix estadísticament en el seu potencial de vol. En adults amb edats d'entre 8-23 dies s'observa un major percentatge de vol que en aquells amb 1-7 dies d'edat. En canvi, l'edat no influeix significativament sobre el seu potencial de vol. En analitzar el vol més llarg, obtenim que més del 63% dels insectes es classifiquen com voladors de curta distància (<500m), el 27.3% de mitja distància (500-5000m), i >9% de llarga distància (>5000m). Finalment, s'ha analitzat en camp el comportament de vol i dispersió de R. ferrugineus mitjançant la tècnica de marcatge-solta-recaptura. Aquest assaig ha permès estudiar la influència del sexe, la temperatura, la humitat relativa i la radiació solar, en l'enlairament i dispersió dels adults. La probabilitat d'enlairament de R. ferrugineus és significativament major en mascles A més, aquesta probabilitat s'incrementa quan la temperatura i la radiació solar augmenten. Respecte a la dispersió de l'insecte mitjançant el vol, el nombre de recaptures es veu influenciat per la temperatura, augmentant significativament quan aquesta s'incrementa. De la mateixa manera, les distàncies de dispersió també s'incrementen significativament a mesura que ho fa la temperatura. L'insecte tendeix a volar distàncies <500m (77.1% dels adults recapturats), seguint la mateixa tendència observada en laboratori. No obstant, R. ferrugineus és capaç de recórrer fins a 7km, arribant-se a registrar vols potencials en laboratori de fins a 20km. Per últim, el temps de dispersió dels adults és molt curt (>90% es recapturaren en els 7 primers die / Ávalos Masó, JA. (2015). Factors influencing the mobility of Red Palm Weevil Rhynchophorus ferrugineus (Coleoptera: Dryophthoridae) adults [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/59394 / Compendio
662

Matrix-assisted laser desorption/ionization- quadrupole ion trap-time of flight mass spectrometry sequencing resolves structures of unidentified peptides obtained by in-gel tryptic digestion of haptoglobin derivatives from human plasma proteomes.

Sutton, Chris W., Glocker, M.O., Koy, C., Tanaka, K., Mikkat, S., Resch, M. 2009 July 1914 (has links)
No / Two-dimensional gel electrophoresis-separated and excised haptoglobin alpha2-chain protein spots were subjected to in-gel digestion with trypsin. Previously unassigned peptide ion signals observed in mass spectrometric fingerprinting experiments were sequenced using the matrix-assisted laser desorption/ionization-quadrupole ion trap-time of flight (MALDI-QIT-TOF) mass spectrometer and showed that the haptoglobin alpha-chain derivative under study was cleaved by trypsin unspecifically. Abundant cleavages occurred C-terminal to histidine residues at H23, H28, and H87. In addition, mild acidic hydrolysis leading to cleavage after aspartic acid residues at D13 was observed. The uninterpreted tandem mass spectrometry (MS/MS) spectrum of the peptide with ion signal at 2620.19 was submitted to database search and yielded the identification of the corresponding peptide sequence comprising amino acids (aa) aa65-87 from the haptoglobin alpha-chain protein. Also, the presence of a mixture of two tryptic peptides (mass to charge ratio m/z 1708.8; aa40-54, and aa99-113, respectively), that is caused by a tiny sequence variation between the two repeats in the haptoglobin alpha2-chain protein was resolved by MS/MS fragmentation using the MALDI-QIT-TOF mass spectrometer instrument. Advantageous features such as (i) easy parent ion creation, (ii) minimal sample consumption, and (iii) real collision induced dissociation conditions, were combined successfully to determine the amino acid sequences of the previously unassigned peptides. Hence, the novel mass spectrometric sequencing method applied here has proven effective for identification of distinct molecular protein structures.
663

<b>Development of a digital Dual-trap mass spectrometer for gas-phase ion/ion chemistry studies of High-Mass Biomolecules</b>

Liangxuan Fu (19154452) 17 July 2024 (has links)
<p dir="ltr">Multiply-charged ions of intact biomolecules generated from electrospray ionization (ESI) have drawn researchers' interest in the field of native mass spectrometry (MS) for decades because these ions carry mass and charge information of the intact molecules and interactions among different units. However, the confinement of multiple charge states in a narrow range of <i>m/z</i> makes mass and charge assignments challenging, especially for analytes with a mass greater than 100 kDa. Gas-phase ion/ion reactions have proven to be powerful techniques that facilitate the interpretation of mass spectra of natively sprayed macromolecular analytes by manipulating the masses and charges of ions detected.</p><p dir="ltr">The proton-transfer reaction (PTR) is the most used gas-phase ion/ion reaction method. It utilizes perfluorinated PTR reagents to "grab" protons away from the analyte ions, thereby reducing their charges. A novel charge state manipulation technique called "ion parking," based on PTR, has been developed. In this method, ion signals are accumulated to one or a range of charge states by selectively inhibiting reactions between the target charge state and the PTR reagents via resonance excitation.</p><p dir="ltr">The multiply-charged ion attachment (MIA) reaction is another gas-phase ion/ion reaction approach. It utilizes the significant <i>m/z</i> displacement caused by the attachment of multiply-charged reagent ions, and it has been proven useful for mass analysis of heterogeneous macromolecular analytes with a mass greater than 1 MDa.</p><p dir="ltr">All gas-phase ion/ion reaction techniques require mutual storage of ions in opposite polarities within an electrodynamic quadrupole ion trap, such as a 3D quadrupole ion trap (QIT) or a linear quadrupole ion trap (LIT). Electrodynamic ion traps use high-voltage (HV) drive radio frequencies (RF) to trap ions in a quadrupolar field, typically employing a sinusoidal waveform (sine wave). A digital quadrupole ion trap (DIT) is an unconventional electrodynamic ion trap that uses a digital waveform (square wave) as the drive RF. The high agility of square waves makes DIT an ideal mass analyzer for studying high <i>m/z</i> ions resulting from gas-phase ion/ion reactions. This dissertation describes the development of a novel home-built digital dual-trap mass spectrometer and ion/ion chemistry studies of large biomolecules within the instrument.</p>
664

Präzisionsmassebestimmung einzelner Partikel im Femtogrammbereich und Anwendungen in der Oberflächenphysik

Illemann, Jens 03 August 2000 (has links) (PDF)
In this work, a new method for mass determination of single low-charged particles in the sub-picogram regime is developed. It opens applications to chemical physics and surface science via determination of growth rates. The method combines the well-known electrodynamic quadrupole ion trap in a UHV-chamber and fourier transformation of scattered light. The achieved mass resolution of down to $10^{-4}$ at 100 fg mass on a time scale of ten seconds allows a resolution of a few percent of the mass of an adsorbed monolayer and to determine growth rates down to one molecule per second on a time scale of one day. The observation of temperature dependent sticking coefficients results in the measures of the energy of an adsorption barrier. Observation of discrete steps in the rate gives information about the density of molecules in an ordered layer. Temperature dependent desorption data gives the binding energy. The dependence of these observables on the controllable curvature and charge of the substrate's surface is measurable. The first part of this dissertation consists of a description of the common theory of the quadrupole ion trap with the completion of not widely known, newly introduced, contributions to the trapping potential. These contributions lead to systematic shifts in the mass determination. In particular the influence of the inhomogenity of the electrical field, that is used for compensating the gravitational force, is investigated analytically and corroborated experimentally. It is assumed, that the particle's finite size effects in a further shift. In the experimental part initial demonstrative measurements are presented: the time-resolved adsorption of fullerene, anthracene and NO on silica spheres with 500nm diameter has been measured at room temperature. In addition the secondary electron yield of in-situ prepared particles during irradiation with monoenergetic electrons has been determined by analyzing the distribution of change of the number of elementary charges by single events of charging.
665

Microenterprise Performance and Economic Development: Evidence from Mexico

Negrete García, Ana Karen 16 June 2017 (has links)
No description available.
666

Präzisionsmassebestimmung einzelner Partikel im Femtogrammbereich und Anwendungen in der Oberflächenphysik

Illemann, Jens 26 July 2000 (has links)
In this work, a new method for mass determination of single low-charged particles in the sub-picogram regime is developed. It opens applications to chemical physics and surface science via determination of growth rates. The method combines the well-known electrodynamic quadrupole ion trap in a UHV-chamber and fourier transformation of scattered light. The achieved mass resolution of down to $10^{-4}$ at 100 fg mass on a time scale of ten seconds allows a resolution of a few percent of the mass of an adsorbed monolayer and to determine growth rates down to one molecule per second on a time scale of one day. The observation of temperature dependent sticking coefficients results in the measures of the energy of an adsorption barrier. Observation of discrete steps in the rate gives information about the density of molecules in an ordered layer. Temperature dependent desorption data gives the binding energy. The dependence of these observables on the controllable curvature and charge of the substrate's surface is measurable. The first part of this dissertation consists of a description of the common theory of the quadrupole ion trap with the completion of not widely known, newly introduced, contributions to the trapping potential. These contributions lead to systematic shifts in the mass determination. In particular the influence of the inhomogenity of the electrical field, that is used for compensating the gravitational force, is investigated analytically and corroborated experimentally. It is assumed, that the particle's finite size effects in a further shift. In the experimental part initial demonstrative measurements are presented: the time-resolved adsorption of fullerene, anthracene and NO on silica spheres with 500nm diameter has been measured at room temperature. In addition the secondary electron yield of in-situ prepared particles during irradiation with monoenergetic electrons has been determined by analyzing the distribution of change of the number of elementary charges by single events of charging.
667

Photoinduced hole trapping in single semiconductor quantum dots at specific sites at silicon oxide interfaces

Krasselt, Cornelius, Schuster, Jörg, von Borczyskowski, Christian 23 September 2013 (has links)
Blinking dynamics of CdSe/ZnS semiconductor quantum dots (QD) are characterized by (truncated) power law distributions exhibiting a wide dynamic range in probability densities and time scales both for off- and on-times. QDs were immobilized on silicon oxide surfaces with varying grades of hydroxylation and silanol group densities, respectively. While the off-time distributions remain unaffected by changing the surface properties of the silicon oxide, a deviation from the power law dependence is observed in the case of on-times. This deviation can be described by a superimposed single exponential function and depends critically on the local silanol group density. Furthermore, QDs in close proximity to silanol groups exhibit both high average photoluminescence intensities and large on-time fractions. The effect is attributed to an interaction between the QDs and the silanol groups which creates new or deepens already existing hole trap states within the ZnS shell. This interpretation is consistent with the trapping model introduced by Verberk et al. (R. Verberk, A. M. van Oijen and M. Orrit, Phys. Rev. B, 2002, 66, 233202).
668

The use of informers during precious medals undercover operations

Flynn, Hendrik Frans 10 1900 (has links)
The research was conducted as a result of the long standing criticism against undercover operations due to the conduct of informers and agents during these operations. Since both undercover operations and informers are controversial issues it may cause serious judicial problems if the system is not applied correctly. The problem was investigated by means of qualitative research. A thorough literature study and semi-structured interviews were used to gather the required data. Semi-structured interviews were conducted with advocates of the Director of Public Prosecutions Free State and detectives from the Organised Crime Unit of the South African Police Service. It has been found that undercover operations are an effective manner to address organised crime and especially precious metals related crimes. Undercover operations are an excellent barometer to determine the extent of organised crime. It gives investigators a clear view of the compilation of a syndicate and the roles of leaders, runners and associates. Informers are invaluable sources of information. Without the use of informers it will be virtually impossible to engage in undercover operations, since the police will have no intelligence to engage into an investigation of this nature. The implications of the findings are that it is the responsibility of investigators, agents and informers to keep the system transparent, fair and acceptable. Their conduct may never violate their mandate and the boundaries of the investigation. Undercover operations are justified when the system is properly administered, structured, controlled and without bias. / Forensic Investigation / M. Tech. (Forensic Investigation)
669

Applications of microfluidic chips in optical manipulation & photoporation

Marchington, Robert F. January 2010 (has links)
Integration and miniaturisation in electronics has undoubtedly revolutionised the modern world. In biotechnology, emerging lab-on-a-chip (LOC) methodologies promise all-integrated laboratory processes, to perform complete biochemical or medical synthesis and analysis encapsulated on small microchips. The integration of electrical, optical and physical sensors, and control devices, with fluid handling, is creating a new class of functional chip-based systems. Scaled down onto a chip, reagent and sample consumption is reduced, point-of-care or in-the-field usage is enabled through portability, costs are reduced, automation increases the ease of use, and favourable scaling laws can be exploited, such as improved fluid control. The capacity to manipulate single cells on-chip has applications across the life sciences, in biotechnology, pharmacology, medical diagnostics and drug discovery. This thesis explores multiple applications of optical manipulation within microfluidic chips. Used in combination with microfluidic systems, optics adds powerful functionalities to emerging LOC technologies. These include particle management such as immobilising, sorting, concentrating, and transportation of cell-sized objects, along with sensing, spectroscopic interrogation, and cell treatment. The work in this thesis brings several key applications of optical techniques for manipulating and porating cell-sized microscopic particles to within microfluidic chips. The fields of optical trapping, optical tweezers and optical sorting are reviewed in the context of lab-on-a-chip application, and the physics of the laminar fluid flow exhibited at this size scale is detailed. Microfluidic chip fabrication methods are presented, including a robust method for the introduction of optical fibres for laser beam delivery, which is demonstrated in a dual-beam optical trap chip and in optical chromatography using photonic crystal fibre. The use of a total internal reflection microscope objective lens is utilised in a novel demonstration of propelling particles within fluid flow. The size and refractive index dependency is modelled and experimentally characterised, before presenting continuous passive optical sorting of microparticles based on these intrinsic optical properties, in a microfluidic chip. Finally, a microfluidic system is utilised in the delivery of mammalian cells to a focused femtosecond laser beam for continuous, high throughput photoporation. The optical injection efficiency of inserting a fluorescent dye is determined and the cell viability is evaluated. This could form the basis for ultra-high throughput, efficient transfection of cells, with the advantages of single cell treatment and unrivalled viability using this optical technique.
670

On Small Mammal Sympatry in the Southeastern Amazon and Ecological Relationships with Brazil Nut Dispersal and Harvesting

Solorzano-Filho, Jorge Alberto 03 March 2010 (has links)
The Amazon rainforest harbors the planet's highest biodiversity among terrestrial ecosystems; however, the biology and ecology of most of its species are unknown. Niche partitioning is considered a key factor allowing species co-existence, especially for morphological similar species such as spiny rats of the genus Proechimys. I examined the extent to which habitat differentiation, species body mass, and diet could explain the community composition of small mammals at a site in the southeastern Amazon. Moreover, I radio-tagged sympatric species of Proechimys spp. and Mesomys stimulax (an arboreal spiny rat) to obtain detailed autoecology information, including habitat use and use of space. I found support for niche partitioning among species and associated small mammal species with distinct successional phases of gap dynamics. I also observed among Proechimys spp. a typical polygynous organization: females appeared to be territorial against females of any species of their genus; but male territories overlapped with those of several females. Mesomys stimulax showed evidence of monogamy and possible sociality, although sample sizes were small. To identify the importance of small mammals as seed disperser of Brazil nut seeds, I conduct experiments using a combination of fluorescent powder, seed exclosures, and track plates in forests with and without Brazil nut groves, and in forests with and without Brazil nut harvesting. Among small mammals, only Proechimys spp. removed, dispersed, and preyed upon Brazil nut seeds. Proechimys spp. sometimes scatterhoarded these seeds, and hence have the potential to play a significant role in recruiting new Brazil nut trees. I also trapped small mammals and measured forest structures on the same sites used for the seed dispersal experiment, to determine the ecological effects of Brazil nut harvest on small mammal communities; however, my results showed little evidence of changes associated with the seed exploitation. My results highlight the importance of habitat heterogeneity in structuring small mammal communities, and indicate that forest management practices that alter habitats, such as partial logging, also can be expected to alter small mammal composition and diversity. Proechimys spp. have the potential to play an important role in the ecological restoration of intensive exploited Brazil nut groves.

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