Architecture of portable electronic medical records system integrated with streaming media.

Science.gov (United States)

Chen, Wei; Shih, Chien-Chou

2012-02-01

Due to increasing occurrence of accidents and illness during business trips, travel, or overseas studies, the requirement for portable EMR (Electronic Medical Records) has increased. This study proposes integrating streaming media technology into the EMR system to facilitate referrals, contracted laboratories, and disease notification among hospitals. The current study encoded static and dynamic medical images of patients into a streaming video format and stored them in a Flash Media Server (FMS). Based on the Taiwan Electronic Medical Record Template (TMT) standard, EMR records can be converted into XML documents and used to integrate description fields with embedded streaming videos. This investigation implemented a web-based portable EMR interchanging system using streaming media techniques to expedite exchanging medical image information among hospitals. The proposed architecture of the portable EMR retrieval system not only provides local hospital users the ability to acquire EMR text files from a previous hospital, but also helps access static and dynamic medical images as reference for clinical diagnosis and treatment. The proposed method protects property rights of medical images through information security mechanisms of the Medical Record Interchange Service Center and Health Certificate Authorization to facilitate proper, efficient, and continuous treatment of patients.

Effects of non-Maxwellian electron velocity distribution function on two-stream instability in low-pressure discharges

International Nuclear Information System (INIS)

Sydorenko, D.; Smolyakov, A.; Kaganovich, I.; Raitses, Y.

2007-01-01

Electron emission from discharge chamber walls is important for plasma maintenance in many low-pressure discharges. The electrons emitted from the walls are accelerated by the sheath electric field and are injected into the plasma as an electron beam. Penetration of this beam through the plasma is subject to the two-stream instability, which tends to slow down the beam electrons and heat the plasma electrons. In the present paper, a one-dimensional particle-in-cell code is used to simulate these effects both in a collisionless plasma slab with immobile ions and in a cross-field discharge of a Hall thruster. The two-stream instability occurs if the total electron velocity distribution function of the plasma-beam system is a nonmonotonic function of electron speed. Low-pressure plasmas can be depleted of electrons with energy above the plasma potential. This study reveals that under such conditions the two-stream instability depends crucially on the velocity distribution function of electron emission. It is shown that propagation of the secondary electron beams in Hall thrusters may be free of the two-stream instability if the velocity distribution of secondary electron emission is a monotonically decaying function of speed. In this case, the beams propagate between the walls with minimal loss of the beam current and the secondary electron emission does not affect the thruster plasma properties

Electron surfing acceleration by the electron two-stream instability in a weak magnetic field

International Nuclear Information System (INIS)

Dieckmann, M E; Shukla, P K

2006-01-01

The thermalization of relativistically flowing colliding plasmas is not well understood. The transition layer, in which both plasmas interact and thermalize, is wide and highly structured and the instabilities in this layer may yield non-thermal particle distributions and shock-less energy dissipation. The objective in this work is to explore the ability of an electron two-stream instability for thermalizing a plasma beam that moves at the mildly relativistic speed 0.3c through weakly magnetized plasma and to identify the resulting particle distributions. It is demonstrated here with particle-in-cell simulations that the electron two-stream instability leads to waves that propagate within a wide angular range relative to the flow velocity. The waves are thus not planar, as required for efficient electron surfing acceleration (ESA). The short lifetime of the waves implies, however, only weak modifications of the ESA by the oblique modes, since the waves are sufficiently homogeneous. The ion (proton) beams are not modulated, which would be required to extract some of their energy. The instability can thus heat the electrons significantly, but it fails to accelerate them to relativistic energies and it cannot form a shock layer by thermalizing the protons, at least not for the system and the resolved timescales considered here

Electron surfing acceleration by the electron two-stream instability in a weak magnetic field

Energy Technology Data Exchange (ETDEWEB)

Dieckmann, M E; Shukla, P K [Institut fuer Theoretische Physik IV, Ruhr-Universitaet Bochum, D-44780 Bochum (Germany)

2006-10-15

The thermalization of relativistically flowing colliding plasmas is not well understood. The transition layer, in which both plasmas interact and thermalize, is wide and highly structured and the instabilities in this layer may yield non-thermal particle distributions and shock-less energy dissipation. The objective in this work is to explore the ability of an electron two-stream instability for thermalizing a plasma beam that moves at the mildly relativistic speed 0.3c through weakly magnetized plasma and to identify the resulting particle distributions. It is demonstrated here with particle-in-cell simulations that the electron two-stream instability leads to waves that propagate within a wide angular range relative to the flow velocity. The waves are thus not planar, as required for efficient electron surfing acceleration (ESA). The short lifetime of the waves implies, however, only weak modifications of the ESA by the oblique modes, since the waves are sufficiently homogeneous. The ion (proton) beams are not modulated, which would be required to extract some of their energy. The instability can thus heat the electrons significantly, but it fails to accelerate them to relativistic energies and it cannot form a shock layer by thermalizing the protons, at least not for the system and the resolved timescales considered here.

Dissolved nutrient exports from natural and human-impacted Neotropical catchments

DEFF Research Database (Denmark)

Gücker, Björn; Silva, Ricky C. S.; Graeber, Daniel

2016-01-01

Aim Neotropical biomes are highly threatened by land-use changes, but the catchment-wide biogeochemical effects are poorly understood. Here, we aim to compare exports of dissolved nitrogen (N) and phosphorus (P) from natural and human-impacted catchments in the Neotropics. Location Neotropics. Me...

A framework to preserve the privacy of electronic health data streams.

Science.gov (United States)

Kim, Soohyung; Sung, Min Kyoung; Chung, Yon Dohn

2014-08-01

The anonymization of health data streams is important to protect these data against potential privacy breaches. A large number of research studies aiming at offering privacy in the context of data streams has been recently conducted. However, the techniques that have been proposed in these studies generate a significant delay during the anonymization process, since they concentrate on applying existing privacy models (e.g., k-anonymity and l-diversity) to batches of data extracted from data streams in a period of time. In this paper, we present delay-free anonymization, a framework for preserving the privacy of electronic health data streams. Unlike existing works, our method does not generate an accumulation delay, since input streams are anonymized immediately with counterfeit values. We further devise late validation for increasing the data utility of the anonymization results and managing the counterfeit values. Through experiments, we show the efficiency and effectiveness of the proposed method for the real-time release of data streams. Copyright © 2014 Elsevier Inc. All rights reserved.

Statistics of counter-streaming solar wind suprathermal electrons at solar minimum: STEREO observations

Directory of Open Access Journals (Sweden)

B. Lavraud

2010-01-01

Full Text Available Previous work has shown that solar wind suprathermal electrons can display a number of features in terms of their anisotropy. Of importance is the occurrence of counter-streaming electron patterns, i.e., with "beams" both parallel and anti-parallel to the local magnetic field, which is believed to shed light on the heliospheric magnetic field topology. In the present study, we use STEREO data to obtain the statistical properties of counter-streaming suprathermal electrons (CSEs in the vicinity of corotating interaction regions (CIRs during the period March–December 2007. Because this period corresponds to a minimum of solar activity, the results are unrelated to the sampling of large-scale coronal mass ejections, which can lead to CSE owing to their closed magnetic field topology. The present study statistically confirms that CSEs are primarily the result of suprathermal electron leakage from the compressed CIR into the upstream regions with the combined occurrence of halo depletion at 90° pitch angle. The occurrence rate of CSE is found to be about 15–20% on average during the period analyzed (depending on the criteria used, but superposed epoch analysis demonstrates that CSEs are preferentially observed both before and after the passage of the stream interface (with peak occurrence rate >35% in the trailing high speed stream, as well as both inside and outside CIRs. The results quantitatively show that CSEs are common in the solar wind during solar minimum, but yet they suggest that such distributions would be much more common if pitch angle scattering were absent. We further argue that (1 the formation of shocks contributes to the occurrence of enhanced counter-streaming sunward-directed fluxes, but does not appear to be a necessary condition, and (2 that the presence of small-scale transients with closed-field topologies likely also contributes to the occurrence of counter-streaming patterns, but only in the slow solar wind prior to

Development of habitat suitability criteria for Neotropical stream fishes and an assessment of their transferability to streams with different conservation status

Directory of Open Access Journals (Sweden)

Fabrício Barreto Teresa

Full Text Available We assessed the preference of 10 fish species for depth and velocity conditions in forested streams from southeastern Brazil using habitat suitability criteria (HSC curves. We also tested whether preference patterns observed in forested streams can be transferred to deforested streams. We used data from fish sampled in 62 five-meter sites in three forested streams to construct preference curves. Astyanax altiparanae, A. fasciatus, Knodus moenkhausii, and Piabina argentea showed a preference for deep slow habitats, whereas Aspidoras fuscoguttatus, Characidium zebra, Cetopsorhamdia iheringi, Pseudopimelodus pulcher, and Hypostomus nigromaculatus showed an opposite pattern: preference for shallow fast habitats. Hypostomus ancistroides showed a multimodal pattern of preference for depth and velocity. To evaluate whether patterns observed in forested streams may be transferred to deforested streams, we sampled 64 five-meters sites in three deforested streams using the same methodology. The preference for velocity was more consistent than for depth, as success in the transferability criterion was 86% and 29% of species, respectively. This indicates that velocity is a good predictor of species abundance in streams, regardless of their condition

Plasma behavior during energetic electron streaming events: Further evidence for substorm-associated magnetic reconnection

International Nuclear Information System (INIS)

Bieber, J.W.; Stone, E.C.; Hones, E.W. Jr.; Baker, D.N.; Bame, S.J.

1982-01-01

A recent study showed that streaming energetic (>200 keV) electrons in Earth's magnetotail are statistically associated with southward magnetic fields and with enhancements of the AE index. It is shown here that the streaming electrons characteristically are preceded by aapprox.15 minute period of tailward plasma flow and followed by a dropout of the plasma sheet, thus demonstrating a clear statistical association between substorms and the classical signatures of magnetic reconnection and plasmoid formation. Additionally, a brief upward surge of mean electron energy preceded plasma dropout in several of the events studied, providing direct evidence of localized, reconnection-associated heating processes

Anomalous electron streaming due to electrostatic modes in tokamak plasmas

International Nuclear Information System (INIS)

Schultz, S.D.; Bers, A.; Ram, A.K.

1993-01-01

The motion of circulating electrons in a tokamak interacting with electrostatic waves (such as lower-hybrid waves) is given by a guiding center Hamiltonian and studied by numerical integration. The unperturbed motion of electron guiding centers is first shown to be integrable, and, in a manner similar to that used in previous works, a set of action-angle coordinates for the orbits are derived which take into account finite aspect ratio and noncircular plasma cross section. Electrostatic modes in the low-frequency, long-wavelength limit are treated as a perturbation to the guiding center Hamiltonian. The waves are generated with low integral values of the toroidal and poloidal mode numbers n and m and satisfy the approximate lower-hybrid dispersion relation k perpendicular /k parallel ∼ ω pe /ω ∼ 10 1.5 . If the number of modes is greater than three, the electron motion parallel to the magnetic field is observed to be stochastic in the phase-space region where v parallel is near the wave parallel phase velocity. On surfaces with rational values of the safety factor q, superposition of modes with degenerate values of the parallel mode number n + (m/q) is shown to result in electron streaming perpendicular to the magnetic field. The speed and direction of this radial motion are observed to have sinusoidal dependence on the poloidal angle. For models including finite magnetic-field shear, the authors find a limit to the extent of the radial streaming of the electrons. Results for the speed of the electron radial motion for typical tokamak parameters are presented

Anomalous conductivity and electron heating in a plasma unstable to the two-stream instability

International Nuclear Information System (INIS)

Clark, W.H.M.; Hamberger, S.M.

1979-01-01

An experiment to excite the electron-ion two-stream instability in a cylindrical Q-machine plasma column is described. The mechanism for establishing a large pulsed electron drift velocity in the plasma by applying a potential difference between the end electrodes is discussed. The pulsed current-voltage characteristic of the plasma column and the temporal evolution of the electron density, drift velocity and thermal velocity are measured. In contrast with the behaviour of some computer simulations of the two-stream instability, the plasma exhibits a constant conductivity and the electron thermal velocity increases to values far in excess of the drift velocity. The electrical dissipation is consistent with the increase of the electron thermal energy, both indicating an anomalous conductivity of the same order as an empirical scaling found in earlier experiments on a toroidal discharge. (author)

Effects of temperate agriculture on neotropical migrant landbirds

Science.gov (United States)

Nicholas L. Rodenhouse; Louis B. Best; Raymond J. O' Connor; Eric K. Bollinger

1993-01-01

The ecology of Neotropical migrant landbirds in temperate farmland is reviewed to develop management recommendations for the conservation of migrants. Migrants constitute about 71% of bird species using farmland and 86% of bird species nesting there. The number and abundances of Neotropical migrants using farmland are greatest in uncultivated edges with trees and...

Wave mode instabilities in a two-stream free-electron laser with a background plasma

International Nuclear Information System (INIS)

Nadrifard, Shabnam; Maraghechi, B; Mohsenpour, T

2013-01-01

A theory is presented for a two-stream free-electron laser (FEL) with a background plasma. A dispersion relation (DR) for the unstable couplings of wave modes is derived using fluid formulation. This DR is solved numerically to find the unstable modes and their growth rate. The effect of the velocity difference of the two electron beams as well as the background plasma on the FEL resonance and the two-stream instability is studied. It is shown that their separate as well as combined effects can increase the growth rates. (paper)

Status and management of neotropical migratory birds: Introduction

Science.gov (United States)

Deborah M.; Peter W. Stangel

1993-01-01

The future for neotropical migratory birds rests with our commitment and ability to provide them adequate habitat during all periods of their life cycle. Our commitment to this cause is apparent in the groundswell of interest in neotropical migrants and the many proactive and coopemtive partnerships resulting from the Partners in Flight - Aves de las Americas...

A quasi-one-dimensional velocity regime of super-thermal electron stream propagation through the solar corona

International Nuclear Information System (INIS)

Levin, B.N.

1984-01-01

The propagation of an inhomogeneous stream of fast electrons through the corona - the type III radio burst source - is considered. It is shown, that the angular spectrum width of plasma waves excited by the stream is defined both by Landau damping by particles of the diffuse component and by damping (in the region of large phase velocities) by particles of the stream itself having large pitch angles. The regime of quasi-one-dimensional diffusion in the velocity space is realized only in the presence of a sufficiently dense diffuse component of super-thermal particles and only for a sufficiently large inhomogeneity scale of the stream. A large scale of the stream space profile is formed, evidently, close to the region of injection of super-thermal particles. It is the result of 'stripping' of part of the electrons from the stream front to its slower part due to essential non-one-dimensionality of the particle diffusion in velocity space. Results obtained may explain, in particular, the evolution of a stream particle angular spectrum in the generation region of type III radio bursts observed by spacecrafts (Lin et al., 1981). For the relatively low energetic part of the stream, the oblique plasma wave stabilization by a diffuse component results in a quasi-one-dimensional regime of diffusion. The latter conserves the beam-like structure of this part of the stream. (orig.)

[Neotropical plant morphology].

Science.gov (United States)

Pérez-García, Blanca; Mendoza, Aniceto

2002-01-01

An analysis on plant morphology and the sources that are important to the morphologic interpretations is done. An additional analysis is presented on all published papers in this subject by the Revista de Biología Tropical since its foundation, as well as its contribution to the plant morphology development in the neotropics.

Special issue: Comparative biogeography of Neotropical primates.

Science.gov (United States)

Lynch Alfaro, Jessica W; Cortés-Ortiz, Liliana; Di Fiore, Anthony; Boubli, Jean P

2015-01-01

New research presented in this special issue of Molecular Phylogenetics and Evolution on the "Phylogeny and Biogeography of Neotropical Primates" greatly improves our understanding of the evolutionary history of the New World monkeys and provides insights into the multiple platyrrhine radiations, diversifications, extinctions, and recolonizations that have taken place over time and over space in the Neotropics. Here, we synthesize genetic and biogeographic research from the past several years to construct an overarching hypothesis for platyrrhine evolution. We also highlight continuing controversies in Neotropical primate biogeography, such as whether the location of origin of platyrrhines was Africa or Asia; whether Patagonian fossil primates are stem or crown platyrrhines; and whether cis- and trans-Andean Neotropical primates were subject to vicariance through Andes mountain building, or instead diversified through isolation in mountain valleys after skirting around the Andes on the northwestern coast of South America. We also consider the role of the Amazon River and its major tributaries in shaping platyrrhine biodiversity, and how and when primates from the Amazon reached the Atlantic Forest. A key focus is on primate colonizations and extirpations in Central America, the Andes, and the seasonally dry tropical forests and savannas (such as the Llanos, Caatinga, and Cerrado habitats), all ecosystems that have been understudied up until now for primates. We suggest that most primates currently inhabiting drier open habitats are relatively recent arrivals, having expanded from rainforest habitats in the Pleistocene. We point to the Pitheciidae as the taxonomic group most in need of further phylogenetic and biogeographic research. Additionally, genomic studies on the Platyrrhini are deeply needed and are expected to bring new surprises and insights to the field of Neotropical primate biogeography. Copyright © 2014 Elsevier Inc. All rights reserved.

RF-driven ion source with a back-streaming electron dump

Science.gov (United States)

Kwan, Joe; Ji, Qing

2014-05-20

A novel ion source is described having an improved lifetime. The ion source, in one embodiment, is a proton source, including an external RF antenna mounted to an RF window. To prevent backstreaming electrons formed in the beam column from striking the RF window, a back streaming electron dump is provided, which in one embodiment is formed of a cylindrical tube, open at one end to the ion source chamber and capped at its other end by a metal plug. The plug, maintained at the same electrical potential as the source, captures these backstreaming electrons, and thus prevents localized heating of the window, which due to said heating, might otherwise cause window damage.

Investigation of plasma stream collision produced by thin films irradiated by powerful pulsed electron beam

International Nuclear Information System (INIS)

Efremov, V P; Demidov, B A; Ivkin, M V; Mescheryakov, A N; Petrov, V A; Potapenko, A I

2006-01-01

Collision of fast plasma streams in vacuum is investigated. Plasma streams were produced by irradiation of thin foils with a powerful pulsed electron beam. Interaction of the plasma flows was studied by using frame and streak cameras. One-dimensional numerical simulation was carried out. Application of this method for porous ICF targets and high-energy physics is discussed

Molecular systematic and historical biogeography of the armored Neotropical catfishes Hypoptopomatinae and Neoplecostominae (Siluriformes: Loricariidae).

Science.gov (United States)

Chiachio, Márcio Cesar; Oliveira, Claudio; Montoya-Burgos, Juan I

2008-11-01

The Neotropics possess the greatest freshwater fish diversity of the world, rendering the study of their evolutionary history extremely challenging. Loricariidae catfishes are one of the most diverse components of the Neotropical ichthyofauna and despite a long history of classification, major issues still need elucidation. Based on a nuclear gene, we present a robust phylogeny of two former loricariid subfamilies: Hypoptopomatinae and Neoplecostominae. Our results show that Neoplecostominae is nested within Hypoptopomatinae, and is the sister group to the former Otothyrini tribe. According to our results, supplemented by morphological observations, we erect two new subfamilies, the Otothyrinae and a new Hypoptopomatinae, and modify the Neoplecostominae by including the genus Pseudotocinclus. The uncovered evolutionary relationships allow a detailed analysis of their historical biogeography. We tested two Dispersal-Extinction-Cladogenesis models for inferring the distribution range evolution of the new subfamilies, and show that the model having no constrains performs better than a model constraining long-range dispersal. The Maximum Likelihood reconstructions of ancestral ranges showed a marked division between the Amazonian origin of the Hypoptopomatinae and the eastern coastal Brazil+Upper Paraná origin of the Neoplecostominae and Otothyrinae. Markedly few instances of dispersal across the border separating the Amazon basin and the Paraná-Paraguay+eastern coastal Brazil+Uruguay were reconstructed. This result is in clear contrast with the historical biogeography of many Neotropical fishes, including other Loricariidae. Part of the dispersal limitation may be explained by divergent ecological specialization: lowland rivers versus mountain streams habitats. Moreover, because most species of the new subfamilies are small, we hypothesize that body size-related effects might limit their dispersal, like predation and energetic cost to migration. Finally

Influence of geometry of the discharge interval on distribution of ion and electron streams at surface of the Penning source cathode

International Nuclear Information System (INIS)

Egiazaryan, G.A.; Khachatrian, Zh.B.; Badalyan, E.S.; Ter-Gevorgyan, E.I.; Hovhannisyan, V.N.

2006-01-01

In the discharge of oscillating electrons, the mechanism of the processes, which controls the distribution of the ion and electron streams over the cathode surface, is investigated experimentally. The influence of the length of the discharge interval on value and distribution of the ion and electron streams is analyzed. The distribution both of ion and electron streams at the cathode surface is determined at different conditions of the discharge. It is shown that for given values of the anode diameter d a =31 mm and the gas pressure P=5x10 -5 Torr, the intensive stream of positive ions falls entirely on the cathode central area in the whole interval of the anode length variation (l a =1-11 cm). At the cathode, the ion current reaches the maximal value at a certain (optimal) value of the anode length that, in turn, depends on the anode voltage U a . The intensive stream of longitudinal electrons forms in the short anodes only (l a =2.5-3.5 cm) and depending on the choice of the discharge regime, may fall both on central and middle parts of the cathode

Phylogenetics of neotropical Platymiscium (Leguminosae

DEFF Research Database (Denmark)

Saslis-Lagoudakis, C. Haris; Chase, Mark W; Robinson, Daniel N

2008-01-01

Platymiscium is a neotropical legume genus of forest trees in the Pterocarpus clade of the pantropical "dalbergioid" clade. It comprises 19 species (29 taxa), distributed from Mexico to southern Brazil. This study presents a molecular phylogenetic analysis of Platymiscium and allies inferred from...

Hearing diversity in moths confronting a neotropical bat assemblage.

Science.gov (United States)

Cobo-Cuan, Ariadna; Kössl, Manfred; Mora, Emanuel C

2017-09-01

The tympanal ear is an evolutionary acquisition which helps moths survive predation from bats. The greater diversity of bats and echolocation strategies in the Neotropics compared with temperate zones would be expected to impose different sensory requirements on the neotropical moths. However, even given some variability among moth assemblages, the frequencies of best hearing of moths from different climate zones studied to date have been roughly the same: between 20 and 60 kHz. We have analyzed the auditory characteristics of tympanate moths from Cuba, a neotropical island with high levels of bat diversity and a high incidence of echolocation frequencies above those commonly at the upper limit of moths' hearing sensitivity. Moths of the superfamilies Noctuoidea, Geometroidea and Pyraloidea were examined. Audiograms were determined by non-invasively measuring distortion-product otoacoustic emissions. We also quantified the frequency spectrum of the echolocation sounds to which this moth community is exposed. The hearing ranges of moths in our study showed best frequencies between 36 and 94 kHz. High sensitivity to frequencies above 50 kHz suggests that the auditory sensitivity of moths is suited to the sounds used by sympatric echolocating bat fauna. Biodiversity characterizes predators and prey in the Neotropics, but the bat-moth acoustic interaction keeps spectrally matched.

Use of neural networks for monitoring surface water quality changes in a neotropical urban stream.

Science.gov (United States)

da Costa, Andréa Oliveira Souza; Silva, Priscila Ferreira; Sabará, Millôr Godoy; da Costa, Esly Ferreira

2009-08-01

This paper reports the using of neural networks for water quality analysis in a tropical urban stream before (2002) and after sewerage building and the completion of point-source control-based sanitation program (2003). Mathematical modeling divided water quality data in two categories: (a) input of some in situ water quality variables (temperature, pH, O2 concentration, O2 saturation and electrical conductivity) and (b) water chemical composition (N-NO2(-); N-NO3(-); N-NH4(+) Total-N; P-PO4(3-); K+; Ca2+; Mg+2; Cu2+; Zn2+ and Fe+3) as the output from tested models. Stream water data come from fortnightly sampling in five points along the Ipanema stream (Southeast Brazil, Minas Gerais state) plus two points downstream and upstream Ipanema discharge into Doce River. Once the best models are consistent with variables behavior we suggest that neural networking shows potential as a methodology to enhance guidelines for urban streams restoration, conservation and management.

A stable production of intense electron beam plasma with ion back stream

International Nuclear Information System (INIS)

Uramoto, Johshin.

1975-12-01

An intense electron beam is extracted without space charge limit from a dc plasma source along a magnetic field. The beam space charge is neutralized stably through back streaming of self-ionized ions from the beam extracting anode region where a neutral gas is fed locally. In Appendix I, a space charge free electron gun is designed under this neutralization method. In Appendix II, a dynamic discharge through a series resistance is described, where an operative mechanism of the well-known TP-D plasma is clarified. (auth.)

Dispersion relation and growth in a two-stream free electron laser with helical wiggler and ion channel guiding

International Nuclear Information System (INIS)

Mehdian, Hassan; Abbasi, Negar

2008-01-01

A linear theory of two-stream free electron laser (FEL) with helical wiggler and ion channel guiding is presented. The dispersion relation is obtained with the help of fluid theory and the growth rate is analyzed through the numerical solutions. The considerable enhancement of the growth rate is demonstrated due to the two-stream instability and continuous tuning of peak growth rate ratio, two-stream FEL compared to single-stream FEL, in terms of varying the ion channel frequency is illustrated

Development of habitat suitability criteria for Neotropical stream fishes and an assessment of their transferability to streams with different conservation status

Directory of Open Access Journals (Sweden)

Fabrício Barreto Teresa

Full Text Available We assessed the preference of 10 fish species for depth and velocity conditions in forested streams from southeastern Brazil using habitat suitability criteria (HSC curves. We also tested whether preference patterns observed in forested streams can be transferred to deforested streams. We used data from fish sampled in 62 five-meter sites in three forested streams to construct preference curves. Astyanax altiparanae, A. fasciatus, Knodus moenkhausii, and Piabina argentea showed a preference for deep slow habitats, whereas Aspidoras fuscoguttatus, Characidium zebra, Cetopsorhamdia iheringi, Pseudopimelodus pulcher, and Hypostomus nigromaculatus showed an opposite pattern: preference for shallow fast habitats. Hypostomus ancistroides showed a multimodal pattern of preference for depth and velocity. To evaluate whether patterns observed in forested streams may be transferred to deforested streams, we sampled 64 five-meters sites in three deforested streams using the same methodology. The preference for velocity was more consistent than for depth, as success in the transferability criterion was 86% and 29% of species, respectively. This indicates that velocity is a good predictor of species abundance in streams, regardless of their conditionNeste estudo avaliamos a preferência de 10 espécies de peixes por condições de profundidade e fluxo em riachos florestados do sudeste do Brasil por meio do critério de adequabilidade de habitat (habitat suitability criteria - curvas HSC. Testamos também se os padrões de preferência observados nos riachos florestados podem ser transferidos para riachos desmatados. Foram realizadas amostragens da ictiofauna em 62 trechos de cinco metros de extensão em três riachos florestados para a construção das curvas de preferência. Astyanax altiparanae, A. fasciatus, Knodus moenkhausii e Piabina argentea apresentaram preferência por habitats lentos e profundos, enquanto Aspidoras fuscoguttatus, Characidium zebra

USDA Forest Service goals and programs for monitoring neotropical migratory birds

Science.gov (United States)

Patricia Manley

1993-01-01

The USDA Forest Service (USFS) developed goals, objectives, and guidelines for monitoring neotropical migratory birds (NTMB) on National Forest System lands in response to the Neotropical Migratory Bird Conservation Program Partners in Flight. A USFS task group developed a hierarchical monitoring framework designed to define priorities for type of monitoring data....

Body size diversity and frequency distributions of Neotropical cichlid fishes (Cichliformes: Cichlidae: Cichlinae.

Directory of Open Access Journals (Sweden)

Sarah E Steele

Full Text Available Body size is an important correlate of life history, ecology and distribution of species. Despite this, very little is known about body size evolution in fishes, particularly freshwater fishes of the Neotropics where species and body size diversity are relatively high. Phylogenetic history and body size data were used to explore body size frequency distributions in Neotropical cichlids, a broadly distributed and ecologically diverse group of fishes that is highly representative of body size diversity in Neotropical freshwater fishes. We test for divergence, phylogenetic autocorrelation and among-clade partitioning of body size space. Neotropical cichlids show low phylogenetic autocorrelation and divergence within and among taxonomic levels. Three distinct regions of body size space were identified from body size frequency distributions at various taxonomic levels corresponding to subclades of the most diverse tribe, Geophagini. These regions suggest that lineages may be evolving towards particular size optima that may be tied to specific ecological roles. The diversification of Geophagini appears to constrain the evolution of body size among other Neotropical cichlid lineages; non-Geophagini clades show lower species-richness in body size regions shared with Geophagini. Neotropical cichlid genera show less divergence and extreme body size than expected within and among tribes. Body size divergence among species may instead be present or linked to ecology at the community assembly scale.

Revision of the Neotropical Xanthandrus Verral (Diptera, Syrphidae

Directory of Open Access Journals (Sweden)

Borges Zuleica M.

2003-01-01

Full Text Available The Neotropical genus Xanthandrus Verral, 1901 is revised. Six species are redescribed: X. bucephalus (Wiedemann, 1830, X. cubanus Fluke, 1936, X. mellinoides (Macquart, 1846, X. mexicanus Curran, 1930, X. nitidulus Fluke, 1937, and X. plaumanni Fluke, 1937. Three species are included based on original descriptions: X. flavomaculatus Shannon, 1927, X. palliatus (Fluke, 1945, and X. simplex (Loew, 1861. New synonyms proposed: Argentinomyia longicornis (Walker, 1837 = Xanthandrus biguttatus Hull, 1945 syn. nov., and Xanthandrus bucephalus (Wiedemann, 1830 = Melanostoma quadrinotata Bigot, 1884 syn. nov. Description of terminalia, a key for Neotropical species, and illustrations are also presented.

Edible species of the fungal genus hebeloma and two neotropical pines

International Nuclear Information System (INIS)

Hernandez, V.C.; Moreno, J.P.; Lizaola, R.Q.; Moreno, J.P.

2015-01-01

Mexico has one of the largest diversities of pines and ectomycorrhizal fungi known world-wide. Therefore, describingnative ectomycorrizal species from the country associated with pines is important because of their biotechnological potential in the forestry and food sectors. Worldwide, Hebeloma has generally been considered a genus of poisonous ectomycorrhizal fungi. However, interestingly, in central Mexico there is a complex of under-studied Hebeloma species which are used as food in large quantities and have a great economic and social importance. Three edible species of Hebeloma widely marketed in the country were identified: Hebeloma alpinum, H. mesophaeum and H. leucosarx with scanning electron microscopy on the basis of different ornamentation patterns in the spores of these species. Synthesis was carried out by inoculating two Neotropical pines with sporomes of the three described Hebeloma species. To achieve this, inoculated pines were kept in greenhouse conditions during one year. A characteristic morphotype for each fungal species was observed and it is described here. The first known description of the morphotype of Hebeloma alpinum with pines is presented. This seminal work gives a tool to identify the morphotypes produced by the main edible ectomycorrhizal species of Hebeloma marketed in Mexico, with biotechnological potential to inoculate pines used in reforestation programmes in Neotropical areas. (author)

Geosynchronous Relativistic Electron Events Associated with High-Speed Solar Wind Streams in 2006

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Sungeun Lee

2009-12-01

Full Text Available Recurrent enhancements of relativistic electron events at geosynchronous orbit (GREEs were observed in 2006. These GREE enhancements were associated with high-speed solar wind streams coming from the same coronal hole. For the first six months of 2006, the occurrence of GREEs has 27 day periodicity and the GREEs were enhanced with various flux levels. Several factors have been studied to be related to GREEs: (1 High speed stream, (2 Pc5 ULF wave activity, (3 Southward IMF Bz, (4 substorm occurrence, (5 Whistler mode chorus wave, and (6 Dynamic pressure. In this paper, we have examined the effectiveness about those parameters in selected periods.

Neotropical lowland forests along environmental gradients

NARCIS (Netherlands)

Toledo, M.

2010-01-01

Neotropical lowlands feature an extraordinary display of vegetation types. This is especially the case for Bolivia where three biogeographical regions, Amazonian, Brazilian-Paranaense and Gran Chaco meet in the lowland areas, providing thus an ideal setting to study vegetation-environment

Comparison of fish assemblages in two littoral habitats in a Neotropical morichal stream in Venezuela

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Carmen G. Montaña

Full Text Available Morichales are lowland streams in South American savannas with riparian forest dominated by the moriche palm (Mauritia flexuosa. We sampled littoral habitats from ten flooded vegetated patches (dominated by Mauritiella aculeate and six sand banks in two months of the dry season (Feb-Mar 2005 in a stream in the savannas of Apure State, Venezuela. We collected samples that compromised 12,407 individual fishes of 107 species. Small-bodied fishes (< 100 mm, representing diverse trophic and life history strategies, were abundant. The most abundant species were in the families Characidae and Cichlidae. Fish assemblages from flooded vegetated patches differed significantly from those on adjacent sand banks. High structural complexity along vegetated shoreline habitats of morichal streams likely contributes to species richness and affects assemblage composition.

A revision of Spondias L. (Anacardiaceae in the Neotropics

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John D. Mitchell

2015-08-01

Full Text Available As part of an ongoing study of Anacardiaceae subfamily Spondioideae, the ten native and one introduced species of Spondias in the Neotropics are revised. The genus is circumscribed. Three new species, S. admirabilis, S. expeditionaria, and S. globosa, are described and illustrated; a key to the taxa found in the Neotropics and distribution maps are provided. The Paleotropical species and allied genera are reviewed. Diagnostic character sets include leaf architecture, habit, flower morphology, and gross fruit morphology. Notes on the ecology and economic botany of the species are provided.

Functional Process Zones Characterizing Aquatic Insect Communities in Streams of the Brazilian Cerrado.

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Godoy, B S; Simião-Ferreira, J; Lodi, S; Oliveira, L G

2016-04-01

Stream ecology studies see to understand ecological dynamics in lotic systems. The characterization of streams into Functional Process Zones (FPZ) has been currently debated in stream ecology because aquatic communities respond to functional processes of river segments. Therefore, we tested if different functional process zones have different number of genera and trophic structure using the aquatic insect community of Neotropical streams. We also assessed whether using physical and chemical variables may complement the approach of using FPZ to model communities of aquatic insects in Cerrado streams. This study was conducted in 101 streams or rivers from the central region of the state of Goiás, Brazil. We grouped the streams into six FPZ associated to size of the river system, presence of riparian forest, and riverbed heterogeneity. We used Bayesian models to compare number of genera and relative frequency of the feeding groups between FPZs. Streams classified in different FPZs had a different number of genera, and the largest and best preserved rivers had an average of four additional genera. Trophic structure exhibited low variability among FPZs, with little difference both in the number of genera and in abundance. Using functional process zones in Cerrado streams yielded good results for Ephemeroptera, Plecoptera, and Trichoptera communities. Thus, species distribution and community structure in the river basin account for functional processes and not necessarily for the position of the community along a longitudinal dimension of the lotic system.

On the Relationship Between High Speed Solar Wind Streams and Radiation Belt Electron Fluxes

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Zheng, Yihua

2011-01-01

Both past and recent research results indicate that solar wind speed has a close connection to radiation belt electron fluxes [e.g., Paulikas and Blake, 1979; Reeves et aI., 2011]: a higher solar wind speed is often associated with a higher level of radiation electron fluxes. But the relationship can be very complex [Reeves et aI., 2011]. The study presented here provides further corroboration of this viewpoint by emphasizing the importance of a global perspective and time history. We find that all the events during years 2010 and 2011 where the >0.8 MeV integral electron flux exceeds 10(exp 5) particles/sq cm/sr/s (pfu) at GEO orbit are associated with the high speed streams (HSS) following the onset of the Stream Interaction Region (SIR), with most of them belonging to the long-lasting Corotating Interaction Region (CIR). Our preliminary results indicate that during HSS events, a maximum speed of 700 km/s and above is a sufficient but not necessary condition for the > 0.8 MeV electron flux to reach 10(exp 5) pfu. But in the exception cases of HSS events where the electron flux level exceeds the 10(exp 5) pfu value but the maximum solar wind speed is less than 700 km/s, a prior impact can be noted either from a CME or a transient SIR within 3-4 days before the arrival of the HSS - stressing the importance of time history. Through superposed epoch analysis and studies providing comparisons with the CME events and the HSS events where the flux level fails to reach the 10(exp 5) pfu, we will present the quantitative assessment of behaviors and relationships of various quantities, such as the time it takes to reach the flux threshold value from the stream interface and its dependence on different physical parameters (e.g., duration of the HSS event, its maximum or average of the solar wind speed, IMF Bz, Kp). The ultimate goal is to apply what is derived to space weather forecasting.

Neotropical fish-fruit interactions: eco-evolutionary dynamics and conservation.

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Correa, Sandra Bibiana; Costa-Pereira, Raul; Fleming, Theodore; Goulding, Michael; Anderson, Jill T

2015-11-01

Frugivorous fish play a prominent role in seed dispersal and reproductive dynamics of plant communities in riparian and floodplain habitats of tropical regions worldwide. In Neotropical wetlands, many plant species have fleshy fruits and synchronize their fruiting with the flood season, when fruit-eating fish forage in forest and savannahs for periods of up to 7 months. We conducted a comprehensive analysis to examine the evolutionary origin of fish-fruit interactions, describe fruit traits associated with seed dispersal and seed predation, and assess the influence of fish size on the effectiveness of seed dispersal by fish (ichthyochory). To date, 62 studies have documented 566 species of fruits and seeds from 82 plant families in the diets of 69 Neotropical fish species. Fish interactions with flowering plants are likely to be as old as 70 million years in the Neotropics, pre-dating most modern bird-fruit and mammal-fruit interactions, and contributing to long-distance seed dispersal and possibly the radiation of early angiosperms. Ichthyochory occurs across the angiosperm phylogeny, and is more frequent among advanced eudicots. Numerous fish species are capable of dispersing small seeds, but only a limited number of species can disperse large seeds. The size of dispersed seeds and the probability of seed dispersal both increase with fish size. Large-bodied species are the most effective seed dispersal agents and remain the primary target of fishing activities in the Neotropics. Thus, conservation efforts should focus on these species to ensure continuity of plant recruitment dynamics and maintenance of plant diversity in riparian and floodplain ecosystems. © 2015 Cambridge Philosophical Society.

Coleopterous galls from the Neotropical region

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Valéria Cid Maia

2012-01-01

Full Text Available Data on Neotropical coleopterous galls were compiled from the literature, which showed that 82 galls have so far been recorded among 77 plant species. The Fabaceae and Asteraceae plant families display the greatest richness in galls. Most galls are induced on stems or buds, while leaves constitute the second most attacked plant organ. Only 16 coleopteran gallers have been identified at the species level; most records are presented at the order level. The identified species belong to four families: Apionidae, Buprestidae, Curculionidae and Erirhinidae. The galls are found in Argentina, Brazil, Belize, Chile, Colombia (probably, Costa Rica, El Salvador, Guatemala, Honduras, Mexico, Nicaragua, Panama and Venezuela. Eighteen species of Coleoptera are inquilines of galls and are associated with 18 plant species, most frequently with Asteraceae, Melastomataceae and Fabaceae. The inquilines were recorded mainly in leaf galls induced by Cecidomyiidae (Diptera. The identity of these weevils is poorly known. General data indicate a lack of taxonomic studies in the Neotropical region.

Habitat shifts in the evolutionary history of a Neotropical flycatcher lineage from forest and open landscapes

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Christidis Les

2008-07-01

Full Text Available Abstract Background Little is known about the role ecological shifts play in the evolution of Neotropical radiations that have colonized a variety of environments. We here examine habitat shifts in the evolutionary history of Elaenia flycatchers, a Neotropical bird lineage that lives in a range of forest and open habitats. We evaluate phylogenetic relationships within the genus based on mitochondrial and nuclear DNA sequence data, and then employ parsimony-based and Bayesian methods to reconstruct preferences for a number of habitat types and migratory behaviour throughout the evolutionary history of the genus. Using a molecular clock approach, we date the most important habitat shifts. Results Our analyses resolve phylogenetic relationships among Elaenia species and confirm several species associations predicted by morphology while furnishing support for other taxon placements that are in conflict with traditional classification, such as the elevation of various Elaenia taxa to species level. While savannah specialism is restricted to one basal clade within the genus, montane forest was invaded from open habitat only on a limited number of occasions. Riparian growth may have been favoured early on in the evolution of the main Elaenia clade and subsequently been deserted on several occasions. Austral long-distance migratory behaviour evolved on several occasions. Conclusion Ancestral reconstructions of habitat preferences reveal pronounced differences not only in the timing of the emergence of certain habitat preferences, but also in the frequency of habitat shifts. The early origin of savannah specialism in Elaenia highlights the importance of this habitat in Neotropical Pliocene and late Miocene biogeography. While forest in old mountain ranges such as the Tepuis and the Brazilian Shield was colonized early on, the most important colonization event of montane forest was in conjunction with Pliocene Andean uplift. Riparian habitats may have

Ultrashort electromagnetic clusters formation by two-stream superheterodyne free electron lasers

DEFF Research Database (Denmark)

Kulish, Viktor V.; Lysenko, Alexander V.; Volk, Iurii I.

2016-01-01

A cubic nonlinear self-consistent theory of multiharmonic two-stream superheterodyne free electron lasers (TSFEL) of a klystron type, intended to form powerful ultrashort clusters of an electromagnetic field is constructed. Plural three-wave parametric resonant interactions of wave harmonics have...... been taken into account. An amplitude, phase and spectral analyses of the processes occurring in such devices have been carried out. The conditions necessary for the forming of the ultrashort clusters of an electromagnetic field have been found out. The possibility of the ultrashort electromagnetic...

Checklist of sea turtles endohelminth in Neotropical region

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Werneck M. R.

2016-09-01

Full Text Available This paper presents a list of parasites described in sea turtles from the Neotropical region. Through the review of literature the occurrence of 79 taxa of helminthes parasites were observed, mostly consisting of the Phylum Platyhelminthes with 76 species distributed in 14 families and 2 families of the Phylum Nematoda within 3 species. Regarding the parasite records, the most studied host was the green turtle (Chelonia mydas followed by the hawksbill turtle (Eretmochelys imbricata, olive ridley turtle (Lepidochelys olivacea, loggerhead turtle (Caretta caretta and leatherback turtle (Dermochelys coriacea. Overall helminths were reported in 12 countries and in the Caribbean Sea region. This checklist is the largest compilation of data on helminths found in sea turtles in the Neotropical region.

A Review of Neotropical Myxomycetes (1828-2008

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Lado, Carlos

2008-12-01

Full Text Available A synthesis of the accumulated knowledge on myxomycetes recorded from the Neotropical region is presented in this paper. The biodiversity of these microorganisms in the Neotropics has been underestimated, and this paper shows that half the known species in the world have been recorded from the region. The monograph by M.L. Farr, for the series Flora Neotropica, published in 1976, has been taken as a baseline. The records produced after this date, some older obscure records, and data from recently published catalogues, monographs and other papers have been incorporated. The information is presented in a table format by species and countries. Species names are listed with synonyms that have been used in Neotropical literature and nomenclature has been updated. A comprehensive list of references by country has been included. A characteristic assemblage of myxomycetes from the Neotropics has been identified. The richness of myxobiota in different countries has been evaluated, and gaps in current information and unexplored areas have become evident from the results. Use of the compiled information to direct conservation plans, and to serve as a starting point to establish and develop future strategies for the study of myxomycetes in this area of the world, is discussed. The importance of prioritizing this research on microorganismal biodiversity, in view of accelerated habitat destruction, is stressed.Se realiza una síntesis sobre el conocimiento actual de los Myxomycetes en el Neotrópico. La biodiversidad de estos microorganismos en la región neotropical ha sido subestimada, pero este trabajo demuestra que la mitad de las especies conocidas en el mundo se han citado de esta región. La monografía que M.L. Farr publicó en 1976, para la serie Flora Neotrópica, se ha tomado como punto de partida para la realización de este trabajo. A ella se han incorporado las citas publicadas después de esta fecha, algunas más antiguas pero raras, y datos de

Status of neotropical migrant landbirds in the Midwest: identifying species of management concern

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Frank R. Thompson; Stephen J. Lewis; Janet D. Green; David N. Ewert

1993-01-01

We ranked species of neotropical migrant landbirds by decreasing management concern for their viability in the Midwest. This was part of a coordinated effort by regional working groups of the Partners In Flight Program, an interagency program for the conservation of neotropical migratory birds (NTMBs). Species were ranked by seven criteria, developed by working group...

Influence of two-stream relativistic electron beam parameters on the space-charge wave with broad frequency spectrum formation

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Alexander, LYSENKO; Iurii, VOLK

2018-03-01

We developed a cubic non-linear theory describing the dynamics of the multiharmonic space-charge wave (SCW), with harmonics frequencies smaller than the two-stream instability critical frequency, with different relativistic electron beam (REB) parameters. The self-consistent differential equation system for multiharmonic SCW harmonic amplitudes was elaborated in a cubic non-linear approximation. This system considers plural three-wave parametric resonant interactions between wave harmonics and the two-stream instability effect. Different REB parameters such as the input angle with respect to focusing magnetic field, the average relativistic factor value, difference of partial relativistic factors, and plasma frequency of partial beams were investigated regarding their influence on the frequency spectrum width and multiharmonic SCW saturation levels. We suggested ways in which the multiharmonic SCW frequency spectrum widths could be increased in order to use them in multiharmonic two-stream superheterodyne free-electron lasers, with the main purpose of forming a powerful multiharmonic electromagnetic wave.

Contribution of conservation genetics in assessing neotropical freshwater fish biodiversity

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NM. Piorski

Full Text Available Human activities have a considerable impact on hydrographic systems and fish fauna. The present review on conservation genetics of neotropical freshwater fish reveals that DNA analyses have been promoting increased knowledge on the genetic structure of fish species and their response to environmental changes. This knowledge is fundamental to the management of wild fish populations and the establishment of Evolutionary Significant Units capable of conserving genetic integrity. While population structuring can occur even in long-distance migratory fish, isolated populations can show reduced genetic variation and be at greater risk of extinction. Phylogeography and phylogeny have been powerful tools in understanding the evolution of fish populations, species and communities in distinct neotropic environments. Captive fish can be used to introduce new individuals and genes into the wild and their benefits and disadvantages can be monitored through genetic analysis. Understanding how fish biodiversity in neotropical freshwaters is generated and maintained is highly important, as these habitats are transformed by human development and fish communities are increasingly exploited as food sources to sustain a growing human population.

Comparative Phylogeography of Neotropical Birds

Science.gov (United States)

2009-05-01

birds, butterflies, plants , soil type, and precipitation (Whitmore and Prance 1987); (C) study populations based largely on neo-tropical lowland...Caballero, A. 1994. Developments in the prediction of effective population size. Heredity 73:657- 679. Camargo, A., R. O. De Sa, and W. R. Heyer. 2006...157-183. Hamrick, J. L., and M. J. W. Godt. 1996. Effects of life history traits on genetic diversity in plant species. Philosophical Transactions Of

Assembly and phylogenetic structure of Neotropical palm communities

DEFF Research Database (Denmark)

Eiserhardt, Wolf L.; Svenning, J.-C.; Balslev, Henrik

Diversity, composition and dynamics of Neotropical palm communities are receiving an increasing amount of attention due to their economic importance, but also because their high species richness and functional diversity render them valuable model systems for overall forest biodiversity. However......, to better understand these palm communities, it is crucial to gain insight into the mechanisms responsible for their assembly. These can be dispersal limitation, environmental filtering, or biotic interactions. If the degree of niche conservatism is known for a group of organisms, patterns of community...... an unspecific assumption of “general niche conservatism”, phylogenetic signal will be analysed for Neotropical palms. Moreover, as an example for evolutionary mechanisms disrupting phylogenetic signal, speciation modes will be examined in selected genera. With the combined results we aim to show the relative...

Morphological variability and distribution of the exotic Asian Mesocyclops thermocyclopoides (Copepoda: Cyclopoida: in the Neotropical region

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Eduardo Suárez-Morales

2011-10-01

Full Text Available From a series of biological samples collected from different freshwater environments in Costa Rica, Central America, the exotic Asian cyclopoid Mesocyclops thermocyclopoides Harada, 1931 was identified. We analyzed the morphology and appendage ornamentation of different Neotropical populations of this species, including specimens from Honduras, southeastern Mexico, and Costa Rica. We also examined Asian specimens from Taiwan, Indonesia, Vietnam, and Thailand, and performed a comparison of the Neotropical and Asian populations including a Principal Component Analysis (PCA. The Neotropical and Asian specimens show subtle morphological variations in the antennules, antennae, mandibles, swimming legs 1-4, and fifth legs. Some characters in the Neotropical group appear to diverge from the Asian pattern and the PCA indicated that intercontinental populations of M. thermocyclopoides are far from being homogeneous. These intra-specific differences are described to expand the known morphological range of this species and to provide the first comparative analysis of an exotic copepod in the Americas. Our analysis suggests that the geographic isolation of the American populations and the subtle morphological divergences with respect to the Asian patterns could be related to speciation processes in the Neotropical region, but also intra-Asian differences are reported. In the Neotropical region this species appears to be restricted to southeastern Mexico, Central America, and one Caribbean island; its potential as biological control of mosquito might enhance its spread in the region.

The diversity and biogeography of late Pleistocene birds from the lowland Neotropics

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Steadman, David W.; Oswald, Jessica A.; Rincón, Ascanio D.

2015-05-01

The Neotropical lowlands sustain the world's richest bird communities, yet little that we know about their history is based on paleontology. Fossils afford a way to investigate distributional shifts in individual species, and thus improve our understanding of long-term change in Neotropical bird communities. We report a species-rich avian fossil sample from a late Pleistocene tar seep (Mene de Inciarte) in northwestern Venezuela. A mere 175 identified fossils from Mene de Inciarte represent 73 species of birds, among which six are extinct, and eight others no longer occur within 100 km. These 14 species consist mainly of ducks (Anatidae), snipe (Scolopacidae), vultures/condors (Vulturidae), hawks/eagles (Accipitridae), and blackbirds (Icteridae). Neotropical bird communities were richer in the late Pleistocene than today; their considerable extinction may be related to collapse of the large mammal fauna at that time. The species assemblage at Mene de Inciarte suggests that biogeographic patterns, even at continental scales, have been remarkably labile over short geological time frames. Mene de Inciarte is but one of 300 + tar seeps in Venezuela, only two of which have been explored for fossils. We may be on the cusp of an exciting new era of avian paleontology in the Neotropics.

Effects of self-fields on electron trajectory and gain in two-stream electromagnetically pumped free-electron laser with ion channel guiding

International Nuclear Information System (INIS)

Saviz, S.; Ghorannevis, M.; Aghamir, Farzin M.; Mehdian, H.

2011-01-01

A theory for the two-stream free-electron laser with an electromagnetic wiggler (EMW) and an ion channel guiding is developed. In the analysis, the effects of self-fields have been taken into account. The electron trajectories and the small signal gain are derived. The stability of the trajectories, the characteristics of the linear gain and the normalized maximum gain are studied numerically. The dependence of the normalized frequency ω-circumflex corresponding to the maximum gain on the ion-channel frequency is presented. The results show that there are seven groups of orbits in the presence of the self-fields, which are similar to those reported in the absence of the self-fields. It is also shown that the normalized gains of 2 groups decrease while the rest increase with the increasing normalized ion-channel frequency. Furthermore, it is found that the two-stream instability and the self-field lead to a decrease in the maximum gain except for group 4. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

Land Use Influences Niche Size and the Assimilation of Resources by Benthic Macroinvertebrates in Tropical Headwater Streams.

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Diego Marcel Parreira de Castro

Full Text Available It is well recognized that assemblage structure of stream macroinvertebrates changes with alterations in catchment or local land use. Our objective was to understand how the trophic ecology of benthic macroinvertebrate assemblages responds to land use changes in tropical streams. We used the isotope methodology to assess how energy flow and trophic relations among macroinvertebrates were affected in environments affected by different land uses (natural cover, pasture, sugar cane plantation. Macroinvertebrates were sampled and categorized into functional feeding groups, and available trophic resources were sampled and evaluated for the isotopic composition of 13C and 15N along streams located in the Cerrado (neotropical savanna. Streams altered by pasture or sugar cane had wider and more overlapped trophic niches, which corresponded to more generalist feeding habits. In contrast, trophic groups in streams with native vegetation had narrower trophic niches with smaller overlaps, suggesting greater specialization. Pasture sites had greater ranges of resources exploited, indicating higher trophic diversity than sites with natural cover and sugar cane plantation. We conclude that agricultural land uses appears to alter the food base and shift macroinvertebrate assemblages towards more generalist feeding behaviors and greater overlap of the trophic niches.

Two new Neotropical species of Ceracis Mellié (Coleoptera, Ciidae) and redefinition of the cucullatus group

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Antunes-Carvalho, Caio; Lopes-Andrade, Cristiano

2011-01-01

Abstract Two new Neotropical species of Ceracis Mellié are described: Ceracis cassumbensis Antunes-Carvalho & Lopes-Andrade, sp. n. from a single locality in northeastern Brazil and Ceracis navarretei Antunes-Carvalho & Lopes-Andrade, sp. n. from a single locality in southern Mexico. Scanning Electron Microscope images of adults and photographs of holotypes and male terminalia are provided for both species, their similarities and differences with other Ceracis are briefly discussed, and the cucullatus species-group is redefined for including the new species described herein. PMID:22140333

Influence of habitat and land use on the assemblages of ephemeroptera, plecoptera, and trichoptera in neotropical streams.

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Amaral, Pedro Henrique Monteiro do; Silveira, Lidimara Souza da; Rosa, Beatriz Figueiraujo Jabour Vescovi; Oliveira, Vívian Campos de; Alves, Roberto da Gama

2015-01-01

Insects of the orders Ephemeroptera, Plecoptera, and Trichoptera (EPT) are often used to assess the conditions of aquatic environments, but few studies have examined the differences in these communities between riffles and pools. Our objective was to test whether riffles shelter greater richness and abundance of EPT, as well as to assess the sensitivity of these insects for detecting impacts from different land uses in streams in southeastern Brazil. Samples were collected in the dry season of 2012 with a Surber sampler in riffles and pools of nine streams (forest, pasture, and urban areas). Principal component analysis distinguished the streams according to different land uses as a function of percentage of plant cover and water oxygenation level and showed partial distinction between riffles and pools as a function of current speed and percentage of ultrafine sand. Detrended correspondence analysis indicated the distinction in EPT composition between riffles and pools, except in urban streams. The results of this study confirm the expected differences in the EPT fauna structure between riffles and pools, especially in forest and pasture environments. The individual metrics of riffle and pool assemblages showed significantly different responses to land use. Therefore, we suggest individual sampling of riffles and pools, since the metrics of these assemblages' insects can differ between these habitats and influence the results of assessments in low-order streams. © The Author 2015. Published by Oxford University Press on behalf of the Entomological Society of America.

Paleocene wind-dispersed fruits and seeds from Colombia and their implications for early Neotropical rainforests

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Herrera Fabiany

2014-12-01

Full Text Available Extant Neotropical rainforests are well known for their remarkable diversity of fruit and seed types. Biotic agents disperse most of these disseminules, whereas wind dispersal is less common. Although wind-dispersed fruits and seeds are greatly overshadowed in closed rainforests, many important families in the Neotropics (e.g., Bignoniaceae, Fabaceae, Malvaceae, Orchidaceae, Sapindaceae show numerous morphological adaptations for anemochory (i.e. wings, accessory hairs. Most of these living groups have high to moderate levels of plant diversity in the upper levels of the canopy. Little is known about the fossil record of wind-dispersed fruits and seeds in the Neotropics. Six new species of disseminules with varied adaptations for wind dispersal are documented here. These fossils, representing extinct genera of Ulmaceae, Malvaceae, and some uncertain families, indicate that wind-dispersed fruit and seed syndromes were already common in the Neotropics by the Paleocene, coinciding with the early development of multistratal rainforests. Although the major families known to include most of the wind-dispersed disseminules in extant rainforests are still missing from the Paleogene fossil record of South and Central America, the new fossils imply that anemochory was a relatively important product and/or mechanism of plant evolution and diversification in early Neotropical rainforests.

Metal particle emissions in the exhaust stream of diesel engines: an electron microscope study.

Science.gov (United States)

Liati, Anthi; Schreiber, Daniel; Dimopoulos Eggenschwiler, Panayotis; Arroyo Rojas Dasilva, Yadira

2013-12-17

Scanning electron microscopy and transmission electron microscopy were applied to investigate the morphology, mode of occurrence and chemical composition of metal particles (diesel ash) in the exhaust stream of a small truck outfitted with a typical after-treatment system (a diesel oxidation catalyst (DOC) and a downstream diesel particulate filter (DPF)). Ash consists of Ca-Zn-P-Mg-S-Na-Al-K-phases (lube-oil related), Fe, Cr, Ni, Sn, Pb, Sn (engine wear), and Pd (DOC coating). Soot agglomerates of variable sizes (1-5 μm, exceptionally 13 μm), rarely engine wear and escape into the atmosphere.

Distributional patterns of the Neotropical genus Thecomyia Perty (Diptera, Sciomyzidae and phylogenetic support

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Amanda Ciprandi Pires

2011-03-01

Full Text Available Distributional patterns of the Neotropical genus Thecomyia Perty (Diptera, Sciomyzidae and phylogenetic support. The distributional pattern of the genus Thecomyia Perty, 1833 was defined using panbiogeographic tools, and analyzed based on the phylogeny of the group. This study sought to establish biogeographical homologies in the Neotropical region between different species of the genus, based on their distribution pattern and later corroboration through its phylogeny. Eight individual tracks and 16 generalized tracks were identified, established along nearly the entire swath of the Neotropics. Individual tracks are the basic units of a panbiogeographic study, and correspond to the hypothesis of minimum distribution of the organisms involved. The generalized tracks, obtained from the spatial congruence between two or more individual tracks, are important in the identification of smaller areas of endemism. Thus, we found evidence from the generalized tracks in support of previous classification for the Neotropical region. The Amazon domain is indicated as an area of outstanding importance in the diversification of the group, by the confluence of generalized tracks and biogeographic nodes in the region. Most of the generalized tracks and biogeographical nodes were congruent with the phylogenetic hypothesis of the genus, indicating support of the primary biogeographical homologies originally defined by the track analysis.

Wildlife survey and monitoring in the Sky Island Region with an emphasis on neotropical felids

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Sergio Avila-Villegas; Jessica Lamberton-Moreno

2013-01-01

The Sky Island region of southwestern United States and northwestern Mexico consists of isolated mountain ranges separated by deserts and grasslands. It mixes elements from five major ecosystems: the Rocky Mountains, Sierra Madre Occidental, the Sonoran and Chihuahuan deserts and the Neotropics. Here some Neotropical species reach their northern ranges, such as jaguars...

DNA barcode detects high genetic structure within neotropical bird species.

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Erika Sendra Tavares

Full Text Available BACKGROUND: Towards lower latitudes the number of recognized species is not only higher, but also phylogeographic subdivision within species is more pronounced. Moreover, new genetically isolated populations are often described in recent phylogenies of Neotropical birds suggesting that the number of species in the region is underestimated. Previous COI barcoding of Argentinean bird species showed more complex patterns of regional divergence in the Neotropical than in the North American avifauna. METHODS AND FINDINGS: Here we analyzed 1,431 samples from 561 different species to extend the Neotropical bird barcode survey to lower latitudes, and detected even higher geographic structure within species than reported previously. About 93% (520 of the species were identified correctly from their DNA barcodes. The remaining 41 species were not monophyletic in their COI sequences because they shared barcode sequences with closely related species (N = 21 or contained very divergent clusters suggestive of putative new species embedded within the gene tree (N = 20. Deep intraspecific divergences overlapping with among-species differences were detected in 48 species, often with samples from large geographic areas and several including multiple subspecies. This strong population genetic structure often coincided with breaks between different ecoregions or areas of endemism. CONCLUSIONS: The taxonomic uncertainty associated with the high incidence of non-monophyletic species and discovery of putative species obscures studies of historical patterns of species diversification in the Neotropical region. We showed that COI barcodes are a valuable tool to indicate which taxa would benefit from more extensive taxonomic revisions with multilocus approaches. Moreover, our results support hypotheses that the megadiversity of birds in the region is associated with multiple geographic processes starting well before the Quaternary and extending to more recent

High abundance of neotropical drosophilids (Diptera: Drosophilidae) in four cultivated areas of central Brazil.

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Emerich, Pp; Valadão, H; Silva, Jrvp; Tidon, R

2012-04-01

The drosophilid assemblages of four cultivated areas (soy, bean, corn, and orange plantations) grown in the core of the Neotropical region were analyzed by comparing their abundances and compositions. The collections, which were gathered using 38 banana traps, captured 12,560 drosophilids, including nine Neotropical and six exotic species. Most of the flies were collected in the bean (43%) and soy (42%) fields. The composition and relative abundance of species also varied among cultivated areas, with orange orchards presenting the highest relative abundance of exotics due to the dominance of the Afrotropical Zaprionus indianus (Gupta). Crop plantations were dominated by a Neotropical species, Drosophila cardini (Sturtevant), which has been shown to be well adapted to dry and disturbed environments. We discuss the drosophilid assemblages of the cultivated areas, comparing them with assemblages from neighbor urban and natural environments. The low drosophilid richness found in this study is similar to the richness found in urban environments and lower than the drosophilid richness of forests, supporting a pattern already known for other taxa. The high abundance of drosophilids in cultivated areas, as well as the dominance of a Neotropical species (D. cardini) in the crop assemblages, was a surprising result.

An Initial Classification of Neotropical Water Mites (Acari: Hydrachnidia Based on Habitat Preferences

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Hugo R. Fernández

2011-01-01

Full Text Available Existing classifications of benthic and interstitial freshwater invertebrates are described and discussed. A classification is proposed for southern neotropical (south of latitude S 15 water mites in relation to their life style and habitat preferences. The classification includes planktonic, superficial, benthic, thermal, and subterranean forms. The diversity of the Hydrachnidia family and genera (22 families, 97 genera, and 521 species is then analyzed using the new classification. Ubiquitous stygobites deserve special consideration because they move through ecotone zones and tolerate extreme conditions. Water mite communities from a north-western Argentinean stream were first described using a surber net and consequently considered as benthic. Nineteen Hydrachnidia species (from benthic to stygobite were collected and classified. The vertical distribution observed during the year confirmed the permanent presence of benthic Hydrachnidia, even during the first flood, which is of special importance in running waters. The functional classification we propose will facilitate comparison of fauna from different areas that have different faunistic composition but may have similar functional distribution.

Biogeographical patterns of Myrcia s.l. (Myrtaceae) and their correlation with geological and climatic history in the Neotropics.

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Santos, Matheus Fortes; Lucas, Eve; Sano, Paulo Takeo; Buerki, Sven; Staggemeier, Vanessa Graziele; Forest, Félix

2017-03-01

Many recent studies discuss the influence of climatic and geological events in the evolution of Neotropical biota by correlating these events with dated phylogenetic hypotheses. Myrtaceae is one of the most diverse Neotropical groups and it therefore a good proxy of plant diversity in the region. However, biogeographic studies on Neotropical Myrtaceae are still very limited. Myrcia s.l. is an informal group comprising three accepted genera (Calyptranthes, Marlierea and Myrcia) making up the second largest Neotropical group of Myrtaceae, totalling about 700 species distributed in nine subgroups. Exclusively Neotropical, the group occurs along the whole of the Neotropics with diversity centres in the Caribbean, the Guiana Highlands and the central-eastern Brazil. This study aims to identify the time and place of divergence of Myrcia s.l. lineages, to examine the correlation in light of geological and climatic events in the Neotropics, and to explore relationships among Neotropical biogeographic areas. A dated phylogenetic hypothesis was produced using BEAST and calibrated by placing Paleomyrtinaea princetonensis (56Ma) at the root of the tree; biogeographic analysis used the DEC model with dispersal probabilities between areas based on distance and floristic affinities. Myrcia s.l. originated in the Montane Atlantic Forest between the end of Eocene and early Miocene and this region acted as a secondary cradle for several lineages during the evolution of this group. The Caribbean region was important in the diversification of the Calyptranthes clade while the Guayana shield appears as ancestral area for an older subgroup of Myrcia s.l. The Amazon Forest has relatively low diversity of Myrcia s.l. species but appears to have been important in the initial biogeographic history of old lineages. Lowland Atlantic Forest has high species diversity but species rich lineages did not originate in the area. Diversification of most subgroups of Myrcia s.l. occurred throughout

Chironomus larvae (Chironomidae: Diptera as water quality indicators along an environmental gradient in a neotropical urban stream

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Nadja Gomes Machado

2015-04-01

Full Text Available Anthropogenic interference in urban lotic systems is a factor affecting the biota of waterbodies. Aquatic macro invertebrates are an important food source for fish and are valuable indicators of water quality. The objective of this work was to study Chironomus larvae (Chironomidae: Diptera distribution along an environmental gradient in Barbado Stream, Cuiabá, MT, Brazil. No individual Chironomus was found in the springs of Barbado Stream, which may indicate preservation of the area. During the study period, we found 40.3 and 94.4 individuals/m2 at points 3 and 4 (low course, respectively. There is eutrophication in these sites due to domestic sewage discharges, indicating low quality water. The Barbado Stream needs restoration projects that include an awareness of the residents of their neighborhood’s environmental importance, and investments in the sanitation sector to prioritize the collection and treatment of wastewater and solid waste collection.

Effects of pesticides and contaminants on neotropical migrants

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Nicholas W. Gard; Michael J. Hooper; Richard S. Bennett

1993-01-01

Many agricultural pesticides and industrial contaminants are capable of adversely affecting birds through direct effects such as elevated mortality rates and decreased reproductive success or indirectly by modifying habitat composition or food availability. Although neotropical migrants are potentially exposed to these contaminants on their breeding, migratory and...

Whimsicality of multi-mode Hasegawa space-charge waves in a complex plasma containing collision-dominated electrons and streaming ions

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Lee, Myoung-Jae; Jung, Young-Dae

2017-09-01

The influence of collision-dominated electrons on multi-mode Hasegawa space-charge waves are investigated in a complex plasma containing streaming ions. The dispersion relation for the multi-mode Hasegawa space-charge wave propagating in a cylindrical waveguide filled with dusty plasma containing collision-dominated electrons and streaming ions is derived by using the fluid equations and Poisson’s equation which lead to a Bessel equation. By the boundary condition, the roots of the Bessel function would characterize the property of space-charge wave propagation. It is found that two solutions exist for wave frequency, which are affected by the radius of waveguide and the roots of the Bessel function. The damping and growing modes are found to be enhanced by an increase of the radius. However, an increase of electron collision frequency would suppress the damping and the growing modes of the propagating space-charge wave in a cylindrical waveguide plasma.

Long-distance calls in Neotropical primates

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Oliveira Dilmar A.G.

2004-01-01

Full Text Available Long-distance calls are widespread among primates. Several studies concentrate on such calls in just one or in few species, while few studies have treated more general trends within the order. The common features that usually characterize these vocalizations are related to long-distance propagation of sounds. The proposed functions of primate long-distance calls can be divided into extragroup and intragroup ones. Extragroup functions relate to mate defense, mate attraction or resource defense, while intragroup functions involve group coordination or alarm. Among Neotropical primates, several species perform long-distance calls that seem more related to intragroup coordination, markedly in atelines. Callitrichids present long-distance calls that are employed both in intragroup coordination and intergroup contests or spacing. Examples of extragroup directed long-distance calls are the duets of titi monkeys and the roars and barks of howler monkeys. Considerable complexity and gradation exist in the long-distance call repertoires of some Neotropical primates, and female long-distance calls are probably more important in non-duetting species than usually thought. Future research must focus on larger trends in the evolution of primate long-distance calls, including the phylogeny of calling repertoires and the relationships between form and function in these signals.

Neotropical Monogenoidea 59. Polyonchoineans from Characidium spp. (Characiformes: Crenuchidae) from southern Brazil.

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Boeger, Walter A; Ferreira, Renata C; Vianna, Rogério T; Patella, Luciana

2014-04-01

Gyrodactylidae and Dactylogyridae (Monogenoidea) are described or reported from three species of Characidium Reinhardt (Crenuchidae), small species of Characiformes, from streams located in southern Brazilian states. Gyrodactylus carolinae sp. n. (Gyrodactylidae) is described from the body surface of Characidium lanei Travassos (type host), C. pterostictum Gomez, and Characidium sp. from streams in the states of Paraná and São Paulo. This new species closely resembles species of Gyrodactylus von Nordmann, 1832 described from species of Poeciliidae, from which it differs by the morphology of the hooks and nucleotide sequences of ITS1-5.8S-ITS2 rDNA. Gyrodactylus inesperatus sp. n. is described from the body surface of Characidium sp. from a stream in the State of São Paulo. The latter new species is characterised by lacking a shield on the superficial bar and by the morphology of the hooks, both unique characteristics for Neotropical species of Gyrodactylus. Marumbius gen. n. (Dactylogyridae) is proposed to accommodate two species, M. dorsivaginatus sp. n. from the gills of Characidium pterostictum (type host) and C. lanei, and M. amplexus sp. n. from the gills of C. lanei (all from the state of Paraná). Both species are characterised by having dorsal vagina, hook pairs 2-4, 6 and 7 composed by two subunits, hook pairs 1 and 5 lacking proximal subunit, and by the length of proximal subunits (when present) varying among hook pairs, completely or partially overlapping gonads, and male copulatory organ (MCO) represented by an incomplete coil of a sclerotized tube articulated to the accessory piece by a copulatory ligament. Cacatuocotyle paranaensis Boeger, Domingues et Kritsky, 1997 is reported from C. lanei at low prevalence in the Rio Marumbi (state of Paraná). The Monogenoidea that parasitize species of Characidium are members of several independent lineages, some of distant evolutionary relationships, suggesting a complex origin for this parasitic fauna.

Biogeographic and diversification patterns of Neotropical Troidini butterflies (Papilionidae support a museum model of diversity dynamics for Amazonia

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Condamine Fabien L

2012-06-01

Full Text Available Abstract Background The temporal and geographical diversification of Neotropical insects remains poorly understood because of the complex changes in geological and climatic conditions that occurred during the Cenozoic. To better understand extant patterns in Neotropical biodiversity, we investigated the evolutionary history of three Neotropical swallowtail Troidini genera (Papilionidae. First, DNA-based species delimitation analyses were conducted to assess species boundaries within Neotropical Troidini using an enlarged fragment of the standard barcode gene. Molecularly delineated species were then used to infer a time-calibrated species-level phylogeny based on a three-gene dataset and Bayesian dating analyses. The corresponding chronogram was used to explore their temporal and geographical diversification through distinct likelihood-based methods. Results The phylogeny for Neotropical Troidini was well resolved and strongly supported. Molecular dating and biogeographic analyses indicate that the extant lineages of Neotropical Troidini have a late Eocene (33–42 Ma origin in North America. Two independent lineages (Battus and Euryades + Parides reached South America via the GAARlandia temporary connection, and later became extinct in North America. They only began substantive diversification during the early Miocene in Amazonia. Macroevolutionary analysis supports the “museum model” of diversification, rather than Pleistocene refugia, as the best explanation for the diversification of these lineages. Conclusions This study demonstrates that: (i current Neotropical biodiversity may have originated ex situ; (ii the GAARlandia bridge was important in facilitating invasions of South America; (iii colonization of Amazonia initiated the crown diversification of these swallowtails; and (iv Amazonia is not only a species-rich region but also acted as a sanctuary for the dynamics of this diversity. In particular, Amazonia probably allowed

Biogeographic and diversification patterns of Neotropical Troidini butterflies (Papilionidae) support a museum model of diversity dynamics for Amazonia.

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Condamine, Fabien L; Silva-Brandão, Karina L; Kergoat, Gael J; Sperling, Felix A H

2012-06-12

The temporal and geographical diversification of Neotropical insects remains poorly understood because of the complex changes in geological and climatic conditions that occurred during the Cenozoic. To better understand extant patterns in Neotropical biodiversity, we investigated the evolutionary history of three Neotropical swallowtail Troidini genera (Papilionidae). First, DNA-based species delimitation analyses were conducted to assess species boundaries within Neotropical Troidini using an enlarged fragment of the standard barcode gene. Molecularly delineated species were then used to infer a time-calibrated species-level phylogeny based on a three-gene dataset and Bayesian dating analyses. The corresponding chronogram was used to explore their temporal and geographical diversification through distinct likelihood-based methods. The phylogeny for Neotropical Troidini was well resolved and strongly supported. Molecular dating and biogeographic analyses indicate that the extant lineages of Neotropical Troidini have a late Eocene (33-42 Ma) origin in North America. Two independent lineages (Battus and Euryades+Parides) reached South America via the GAARlandia temporary connection, and later became extinct in North America. They only began substantive diversification during the early Miocene in Amazonia. Macroevolutionary analysis supports the "museum model" of diversification, rather than Pleistocene refugia, as the best explanation for the diversification of these lineages. This study demonstrates that: (i) current Neotropical biodiversity may have originated ex situ; (ii) the GAARlandia bridge was important in facilitating invasions of South America; (iii) colonization of Amazonia initiated the crown diversification of these swallowtails; and (iv) Amazonia is not only a species-rich region but also acted as a sanctuary for the dynamics of this diversity. In particular, Amazonia probably allowed the persistence of old lineages and contributed to the steady

A preliminary survey of foliar sclerenchyma in neotropical Loranthaceae

NARCIS (Netherlands)

Kuijt, J.; Lye, D.

2005-01-01

The foliar sclerenchyma of all genera of neotropical Loranthaceae is surveyed by means of cleared leaves, using selected species. Three general categories of sclerenchyma are recognized. Fibers may form discontinuous or continuous bundles associated with veins or, more rarely, occur as individual

Pterandra pyroidea: a case of pollination shift within Neotropical Malpighiaceae

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Cappellari, Simone C.; Haleem, Muhammad A.; Marsaioli, Anita J.; Tidon, Rosana; Simpson, Beryl B.

2011-01-01

Background and Aims Most Neotropical species of Malpighiaceae produce floral fatty oils in calyx glands to attract pollinating oil-collecting bees, which depend on this resource for reproduction. This specialized type of pollination system tends to be lost in members of the family that occur outside the geographic distribution (e.g. Africa) of Neotropical oil-collecting bees. This study focused on the pollination ecology, chemical ecology and reproductive biology of an oil flower species, Pterandra pyroidea (Malpighiaceae) from the Brazilian Cerrado. Populations of this species consist of plants with oil-secreting (glandular) flowers, plants with non-oil-secreting flowers (eglandular) or a mix of both plant types. This study specifically aims to clarify the role of eglandular morphs in this species. Methods Data on pollinators were recorded by in situ observations. Breeding system experiments were conducted by isolating inflorescences and by enzymatic reactions. Floral resources, pollen and floral oils offered by this species were analysed by staining and a combination of various spectroscopic methods. Key Results Eglandular flowers of P. pyroidea do not act as mimics of their oil-producing conspecifics to attract pollinators. Instead, both oil-producing and oil-free flowers depend on pollen-collecting bees for reproduction, and their main pollinators are bumble-bees. Floral oils produced by glandular flowers are less complex than those described in closely related genera. Conclusions Eglandular flowers represent a shift in the pollination system in which oil is being lost and pollen is becoming the main reward of P. pyroidea flowers. Pollination shifts of this kind have hitherto not been demonstrated empirically within Neotropical Malpighiaceae and this species exhibits an unusual transition from a specialized towards a generalized pollination system in an area considered the hotspot of oil-collecting bee diversity in the Neotropics. Transitions of this type

Psittacid herpesviruses associated with mucosal papillomas in neotropical parrots

International Nuclear Information System (INIS)

Styles, Darrel K.; Tomaszewski, Elizabeth K.; Jaeger, Laurie A.; Phalen, David N.

2004-01-01

Mucosal papillomas are relatively common lesions in several species of captive neotropical parrots. They cause considerable morbidity and in some cases, result in mortality. Previous efforts to identify papillomavirus DNA and proteins in these lesions have been largely unsuccessful. In contrast, increasing evidence suggests that mucosal papillomas may contain psittacid herpesviruses (PsHVs). In this study, 41 papillomas from 30 neotropical parrots were examined by PCR with PsHV-specific primers. All 41 papillomas were found to contain PsHV DNA. This 100% prevalence of PsHV infection in the papilloma population was found to be significantly higher than PsHV infection prevalence observed in other surveys of captive parrots. PsHV genotypes 1, 2, and 3, but not 4 were found in these lesions. Psittacus erithacus papillomavirus DNA and finch papillomavirus DNA were not found in the papillomas. A papilloma from a hyacinth macaw (Anodorhynchus hyacinthinus) was found to contain cells that had immunoreactivity to antiserum made to the common antigenic region of human papillomavirus (HPV) L1 major capsid protein. However, four other mucosal papillomas were negative for this immunoreactivity, and negative control tissues from a parrot embryo showed a similar staining pattern to that seen in the cloaca papilloma of the hyacinth macaw, strongly suggesting that the staining seen in hyacinth macaw papilloma was nonspecific. Based on these findings, it was concluded that specific genotypes of PsHV play a direct role in the development of mucosal papillomas of neotropical parrots and there is no evidence to suggest the concurrent presence of a papillomavirus in these lesions

Neotropical species of Meteorus Haliday (Hymenoptera: Braconidae: Meteorinae) parasitizing Arctiinae (Lepidoptera: Noctuoidea: Erebidae).

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Aguirre, Helmuth; Shaw, Scott R

2014-03-17

Three new species of Meteorus parasitoids of Arctiinae are described: Meteorus anuae n. sp., M. juliae n. sp. and M. mirandae n. sp. The first biological record for M. cecavorum Aguirre & Shaw as well as its cocoon description is reported. A comprehensive key for the Neotropical Meteorus attacking Arctiinae is provided. A total of nine Meteorus species have been reared from Arctiinae in the Neotropical Region. Six of them are gregarious and three solitary. The biological information about host and food plants concurs with the hypothesis of specialist parasitoids preferring "nasty" caterpillars.

Depredación de aves acuáticas por la nutria neotropical (Lontra longicaudis annectens, en el río Yaqui, Sonora, México Aquatic bird predation by neotropical river otter (Lontra longicaudis annectens, at Rio Yaqui, Sonora, Mexico

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Juan Pablo Gallo-Reynoso

2008-06-01

Full Text Available Se registra la depredación de aves acuáticas por la nutria neotropical (L. longicaudis annectens en el río Yaqui, Sonora. Se colectaron e identificaron 25 cráneos, porciones de esqueleto postcraneal y plumas de aves encontrados en los comederos de las nutrias; las especies identificadas fueron el cormorán neotropical (Phalacrocorax brasilianus con 16 individuos, el pato de collar (Anas platyrhynchos diazi, 4 individuos; la garza blanca (Ardea alba, 3 individuos; el huaco de corona amarilla (Nyctanassa violacea y el pelícano café (Pelecanus occidentalis, ambos con 1 individuo. En los peces se encontró la tilapia del género Oreochromis. Probablemente los hábitos alimenticios de esta especie responden a la estacionalidad y al consumo de presas más disponibles en el hábitat. Estos registros confirman que las nutrias de río son depredadores oportunistas cuya dieta tiene una amplio rango de uso de especies de los ambientes riparios, además dichos registros son una razón más para considerar la nutria neotropical como especie sombrilla para la conservación de ecosistemas completos, ya que su presencia es un indicador de alta disponibilidad energética y de alta biodiversidad.We report the predation of aquatic birds by neotropical river otters (L. longicaudis annectens at Río Yaqui, Sonora. As many as 25 skulls, post-cranial skeletons and feathers were found at river otter feeding sites. The neotropical cormorant (Phalacrocorax brasilianus was the most predated bird with 16 individuals, followed by Mexican mallard (Anas platyrhynchos diazi with 4 individuals, great egret (Ardea alba with 3 individuals, yellow-crowned night-heron (Nyctanassa violacea, and brown pelican (Pelecanus occidentalis, both with 1 individual. With respect to fish, the tilapia Oreochromis, was the only species found in scats. Neotropical river otter feeding habits were associated with food availability at different seasons of the year. These records show that

Molecular Ecological Insights into Neotropical Bird-Tick Interactions.

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Matthew J Miller

Full Text Available In the tropics, ticks parasitize many classes of vertebrate hosts. However, because many tropical tick species are only identifiable in the adult stage, and these adults usually parasitize mammals, most attention on the ecology of tick-host interactions has focused on mammalian hosts. In contrast, immature Neotropical ticks are often found on wild birds, yet difficulties in identifying immatures hinder studies of birds' role in tropical tick ecology and tick-borne disease transmission. In Panama, we found immature ticks on 227 out of 3,498 individually-sampled birds representing 93 host species (24% of the bird species sampled, and 13% of the Panamanian land bird fauna. Tick parasitism rates did not vary with rainfall or temperature, but did vary significantly with several host ecological traits. Likewise, Neotropical-Nearctic migratory birds were significantly less likely to be infested than resident species. Using a molecular library developed from morphologically-identified adult ticks specifically for this study, we identified eleven tick species parasitizing birds, indicating that a substantial portion of the Panamanian avian species pool is parasitized by a diversity of tick species. Tick species that most commonly parasitized birds had the widest diversity of avian hosts, suggesting that immature tick species are opportunistic bird parasites. Although certain avian ecological traits are positively associated with parasitism, we found no evidence that individual tick species show specificity to particular avian host ecological traits. Finally, our data suggest that the four principal vectors of Rocky Mountain Spotted Fever in the Neotropics rarely, if ever, parasitize Panamanian birds. However, other tick species that harbor newly-discovered rickettsial parasites of unknown pathogenicity are frequently found on these birds. Given our discovery of broad interaction between Panamanian tick and avian biodiversity, future work on tick ecology

Molecular Ecological Insights into Neotropical Bird-Tick Interactions.

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Miller, Matthew J; Esser, Helen J; Loaiza, Jose R; Herre, Edward Allen; Aguilar, Celestino; Quintero, Diomedes; Alvarez, Eric; Bermingham, Eldredge

2016-01-01

In the tropics, ticks parasitize many classes of vertebrate hosts. However, because many tropical tick species are only identifiable in the adult stage, and these adults usually parasitize mammals, most attention on the ecology of tick-host interactions has focused on mammalian hosts. In contrast, immature Neotropical ticks are often found on wild birds, yet difficulties in identifying immatures hinder studies of birds' role in tropical tick ecology and tick-borne disease transmission. In Panama, we found immature ticks on 227 out of 3,498 individually-sampled birds representing 93 host species (24% of the bird species sampled, and 13% of the Panamanian land bird fauna). Tick parasitism rates did not vary with rainfall or temperature, but did vary significantly with several host ecological traits. Likewise, Neotropical-Nearctic migratory birds were significantly less likely to be infested than resident species. Using a molecular library developed from morphologically-identified adult ticks specifically for this study, we identified eleven tick species parasitizing birds, indicating that a substantial portion of the Panamanian avian species pool is parasitized by a diversity of tick species. Tick species that most commonly parasitized birds had the widest diversity of avian hosts, suggesting that immature tick species are opportunistic bird parasites. Although certain avian ecological traits are positively associated with parasitism, we found no evidence that individual tick species show specificity to particular avian host ecological traits. Finally, our data suggest that the four principal vectors of Rocky Mountain Spotted Fever in the Neotropics rarely, if ever, parasitize Panamanian birds. However, other tick species that harbor newly-discovered rickettsial parasites of unknown pathogenicity are frequently found on these birds. Given our discovery of broad interaction between Panamanian tick and avian biodiversity, future work on tick ecology and the dynamics of

Population trends and management opportunities for neotropical migrants

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Chandler S. Robbins; John. R. Sauer; Bruce G. Peterjohn

1993-01-01

The Breeding Bird Survey shows that certain Neotropical migrant songbird populations have been declining over the past 26 years. Among them are forest birds that require extensive forest on the breeding grounds and also forested habitats on tropical wintering grounds. Other species have shown significant declines only since the early 1980's. Birds with broader...

[Geographic data for Neotropical bats (Chiroptera)].

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Noguera-Urbano, Elkin A; Escalante, Tania

2014-03-01

The global effort to digitize biodiversity occurrence data from collections, museums and other institutions has stimulated the development of important tools to improve the knowledge and conservation of biodiversity. The Global Biodiversity Information Facility (GBIF) enables and opens access to biodiversity data of 321 million of records, from 379 host institutions. Neotropical bats are a highly diverse and specialized group, and the geographic information about them is increasing since few years ago, but there are a few reports about this topic. The aim of this study was to analyze the number of digital records in GBIF of Neotropical bats with distribution in 21 American countries, evaluating their nomenclatural and geographical consistence at scale of country. Moreover, we evaluated the gaps of information on 1 degrees latitude x 1 degrees longitude grids cells. There were over 1/2 million records, but 58% of them have no latitude and longitude data; and 52% full fit nomenclatural and geographic evaluation. We estimated that there are no records in 54% of the analyzed area; the principal gaps are in biodiversity hotspots like the Colombian and Brazilian Amazonia and Southern Venezuela. In conclusion, our study suggests that available data on GBIF have nomenclatural and geographic biases. GBIF data represent partially the bat species richness and the main gaps in information are in South America.

Origin and management of neotropical cassava arthropod pests ...

African Journals Online (AJOL)

Cassava, one of the worlds major food crops is grown throughout the tropical regions of the world. Cassava originated in the neotropics; it was introduced into West Africa from Brazil by slave traders in the 1500's, and taken to Asia during the 17th century. Consequently the greatest diversity of cassava pests, as well as their ...

The neotropical genus Opeatocerata Melander (Díptera, Empididae

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Kenneth G. V. Smith

1989-01-01

Full Text Available The Neotropical empidid genus Opeatocerata Melander, hitherto known from only a sigle female from Mexico, is redefined in the light of new material, including males. Three new species are described and illustrated, a key provided and the presence of the genus now additionally established in Costa Rica, Panama, Bolivia, Ecuador, Trinidad and Brazil.

Wood anatomy of the neotropical Sapotaceae : XIV. Elaeoluma

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Bohumil Francis Kukachka

1980-01-01

The genus Elaeoluma consists of three species distributed in the Amazon Basin, Surinam, Guyana, and Venezuela. The description presented here is based on E. glabrescens of the Amazon Basin. The wood is easily differentiated from all other neotropical Sapotaceae by its pale brown color, reticulate parenchyma, which is hardly discernable with a hand lens, and a low...

Plural three-wave resonances of space charge wave harmonics in transit section of klystron-type two-stream FEL with helical electron beam

DEFF Research Database (Denmark)

Lysenko, Alexander; Volk, Iurii; Serozhko, Anastasia

2017-01-01

We have carried out the research of plural three-wave resonances of space charge wave (SCW) harmonics in the transit section of the klystron type two-stream superheterodyne free-electron laser (TSFEL) with helical electron beam in cubic non-linear approximation. We have found out that two...

Molecular phylogeny and historical biogeography of the neotropical swarm-founding social wasp genus Synoeca (Hymenoptera: Vespidae.

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Rodolpho Santos Telles Menezes

Full Text Available The Neotropical Region harbors high biodiversity and many studies on mammals, reptiles, amphibians and avifauna have investigated the causes for this pattern. However, there is a paucity of such studies that focus on Neotropical insect groups. Synoeca de Saussure, 1852 is a Neotropical swarm-founding social wasp genus with five described species that is broadly and conspicuously distributed throughout the Neotropics. Here, we infer the phylogenetic relationships, diversification times, and historical biogeography of Synoeca species. We also investigate samples of the disjoint populations of S. septentrionalis that occur in both northwestern parts of South America through Central American and the Brazilian Atlantic rainforests. Our results showed that the interspecific relationships for Synoeca could be described as follows: (S. chalibea + S. virginea + (S. cyanea + (S. septentrionalis/S. surinama. Notably, samples of S. septentrionalis and S. surinama collected in the Atlantic Forest were interrelated and may be the result of incomplete lineage sorting and/or mitochondrial introgression among them. Our Bayesian divergence dating analysis revealed recent Plio-Pleistocene diversification in Synoeca. Moreover, our biogeographical analysis suggested an Amazonian origin of Synoeca, with three main dispersal events subsequently occurring during the Plio-Pleistocene.

Molecular Phylogeny and Historical Biogeography of the Neotropical Swarm-Founding Social Wasp Genus Synoeca (Hymenoptera: Vespidae)

Science.gov (United States)

Menezes, Rodolpho Santos Telles; Brady, Seán Gary; Carvalho, Antônio Freire; Del Lama, Marco Antonio; Costa, Marco Antônio

2015-01-01

The Neotropical Region harbors high biodiversity and many studies on mammals, reptiles, amphibians and avifauna have investigated the causes for this pattern. However, there is a paucity of such studies that focus on Neotropical insect groups. Synoeca de Saussure, 1852 is a Neotropical swarm-founding social wasp genus with five described species that is broadly and conspicuously distributed throughout the Neotropics. Here, we infer the phylogenetic relationships, diversification times, and historical biogeography of Synoeca species. We also investigate samples of the disjoint populations of S. septentrionalis that occur in both northwestern parts of South America through Central American and the Brazilian Atlantic rainforests. Our results showed that the interspecific relationships for Synoeca could be described as follows: (S. chalibea + S. virginea) + (S. cyanea + (S. septentrionalis/S. surinama)). Notably, samples of S. septentrionalis and S. surinama collected in the Atlantic Forest were interrelated and may be the result of incomplete lineage sorting and/or mitochondrial introgression among them. Our Bayesian divergence dating analysis revealed recent Plio-Pleistocene diversification in Synoeca. Moreover, our biogeographical analysis suggested an Amazonian origin of Synoeca, with three main dispersal events subsequently occurring during the Plio-Pleistocene. PMID:25738705

The neotropical species of Xanthopimpla Saussure (Hymenoptera: Ichneumonidae: Pimplinae).

Science.gov (United States)

Gómez, Isrrael C; Sääksjärvi, Ilari E; Broad, Gavin R; Puhakka, Liisa; Castillo, Carol; Peña, Carlos; Pádua, Diego G

2014-03-04

Xanthopimpla Saussure, 1892 is one of the largest and best studied genera of the family Ichneumonidae. It is most species rich in the Oriental and Afrotropical regions with only a few species occurring in Central and South America. The present study reviews the Neotropical species of the genus including descriptions of four new species from Amazonia and Northeast South America. We define a new species group: the amazonica species-group, to accommodate the following five species: X. amazonica Gómez, Sääksjärvi & Veijalainen, X. guianensis Gómez & Sääksjärvi sp. n., X. jussilai Veijalainen, Sääksjärvi & Broad, X. pucallpensis Gómez & Sääksjärvi sp. n. and X. vidali Gómez sp. n. The aurita species-group, which had hitherto been regarded as the only species-group in the Neotropical region, is currently represented by five species: X. allpahuaya Gómez & Sääksjärvi sp. n., X. aurita Krieger, X. craspedoptera Krieger, X. rhabdomera Townes and X. spiloptera Krieger. The Andean species X. peruana Krieger is established as an unplaced species outside of the amazonica and aurita species-groups. A key to Neotropical species-groups and species of Xanthopimpla is provided. Xanthopimpla aurita is recorded for the first time from Ecuador and Colombia and its extensive distribution is discussed. Xanthopimpla amazonica, X. craspedoptera and X. jussilai are recorded for the first time from Brazil; X. amazonica is recorded for the first time from French Guiana; X. spiloptera is recorded for the first time from French Guiana and Peru, and X. rhabdomera is recorded for the first time from Peru. 

Toxoplasma gondii in small neotropical wild felids

Directory of Open Access Journals (Sweden)

William Alberto Cañon-Franco

2013-02-01

Full Text Available In the last decade, studies on wildlife worldwide have discovered key epidemiological aspects of the sylvatic cycle of Toxoplasma gondii. However, despite the known role of wild felines as definitive hosts in the transmission and maintenance of this parasite, few studies have focused on the involvement of these animals. Brazil exhibits the largest number of wild felid species in the Americas, all of which have a critical conservation status. However, serological detections, epidemiological studies and some molecular characterizations of T. gondii have primarily used Neotropical felid populations that are maintained in captivity, which does not reflect the disease behavior in free-living conditions. A systematic review of the worldwide scientific literature was conducted focusing on toxoplasmosis in small Neotropical felids. This review covered a number of aspects, including the state of scientific research, parasite transmission in the wild, the genetic characteristics of isolates, the relationship between these genetic characteristics and the pathogenicity of the parasite, and the risk factors linked to conflicts with humans. The present review shows the relevance of studying these felid populations based on their frequent interactions with humans in peri-urban areas and the need for further comprehensive studies to establish the real significance of T. gondii in public and animal health in tropical and temperate regions.

Atlantic forests to the all Americas: Biogeographical history and divergence times of Neotropical Ficus (Moraceae).

Science.gov (United States)

Machado, Anderson Ferreira Pinto; Rønsted, Nina; Bruun-Lund, Sam; Pereira, Rodrigo Augusto Santinelo; Paganucci de Queiroz, Luciano

2018-05-01

Ficus (Moraceae) is well diversified in the Neotropics with two lineages inhabiting the wet forests of this region. The hemiepiphytes of section Americanae are the most diversified with c. 120 species, whereas section Pharmacosycea includes about 20 species mostly with a terrestrial habit. To reconstruct the biogeographical history and diversification of Ficus in the Americas, we produced a dated Bayesian phylogenetic hypothesis of Neotropical Ficus including two thirds of the species sequenced for five nuclear regions (At103, ETS, G3pdh, ITS/5.8S and Tpi). Ancestral range was estimated using all models available in Biogeobears and Binary State Speciation and Extinction analysis was used to evaluate the role of the initial habit and propagule size in diversification. The phylogenetic analyses resolved both Neotropical sections as monophyletic but the internal relationships between species in section Americanae remain unclear. Ficus started their diversification in the Neotropics between the Oligocene and Miocene. The genus experienced two bursts of diversification: in the middle Miocene and the Pliocene. Colonization events from the Amazon to adjacent areas coincide with the end of the Pebas system (10 Mya) and the connection of landmasses. Divergence of endemic species in the Atlantic forest is inferred to have happened after its isolation and the opening and consolidation of the Cerrado. Our results suggest a complex diversification in the Atlantic forest differing between postulated refuges and more instable areas in the South distribution of the forest. Finally the selection for initial hemiepiphytic habit and small to medium propagule size influenced the diversification and current distribution of the species at Neotropical forests marked by the historical instability and long-distance dispersal. Copyright © 2018 Elsevier Inc. All rights reserved.

Wood anatomy of the neotropical Sapotaceae. VII, Chrysophyllum

Science.gov (United States)

B. F. Kukachka

1978-01-01

In the neotropics, the genus Chrysophyllum consists of C. cainito and a number of species which have recently been assigned to the genus Cynodendron. Many taxonomists have not accepted the new genus Cynodendron and this is supported by the present study of the wood anatomy. In this restricted sense, Chrysophyllum consists of a group of closely related species that are...

Nonlinear two-stream interaction between a cold, relativistic electron beam and a collisional plasma-Astron experiment

International Nuclear Information System (INIS)

Newberger, B.S.; Thode, L.E.

1979-05-01

Experiments on the two-stream instability of a relativistic electron beam propagating through a neutral gas, carried out with the Lawrence Livermore Laboratory Astron beam, have been analyzed using a nonlinear saturation model for a cold beam. The behavior of the observed microwave emission due to the instability is in good agreement with that of the beam energy loss. Collisions on the plasma electrons weaken the nonlinear state of the instability but do not stabilize the mode. The beam essentially acts as if it were cold, a result substantiated by linear theory for waves propagating along the beam. In order to predict the effect of both beam momentum scatter and plasma electron collisions on the stability of the mode in future experiments a full two-dimensional linear theory must be developed

A comparison of large-scale electron beam and bench-scale 60Co irradiations of simulated aqueous waste streams

Science.gov (United States)

Kurucz, Charles N.; Waite, Thomas D.; Otaño, Suzana E.; Cooper, William J.; Nickelsen, Michael G.

2002-11-01

The effectiveness of using high energy electron beam irradiation for the removal of toxic organic chemicals from water and wastewater has been demonstrated by commercial-scale experiments conducted at the Electron Beam Research Facility (EBRF) located in Miami, Florida and elsewhere. The EBRF treats various waste and water streams up to 450 l min -1 (120 gal min -1) with doses up to 8 kilogray (kGy). Many experiments have been conducted by injecting toxic organic compounds into various plant feed streams and measuring the concentrations of compound(s) before and after exposure to the electron beam at various doses. Extensive experimentation has also been performed by dissolving selected chemicals in 22,700 l (6000 gal) tank trucks of potable water to simulate contaminated groundwater, and pumping the resulting solutions through the electron beam. These large-scale experiments, although necessary to demonstrate the commercial viability of the process, require a great deal of time and effort. This paper compares the results of large-scale electron beam irradiations to those obtained from bench-scale irradiations using gamma rays generated by a 60Co source. Dose constants from exponential contaminant removal models are found to depend on the source of radiation and initial contaminant concentration. Possible reasons for observed differences such as a dose rate effect are discussed. Models for estimating electron beam dose constants from bench-scale gamma experiments are presented. Data used to compare the removal of organic compounds using gamma irradiation and electron beam irradiation are taken from the literature and a series of experiments designed to examine the effects of pH, the presence of turbidity, and initial concentration on the removal of various organic compounds (benzene, toluene, phenol, PCE, TCE and chloroform) from simulated groundwater.

A comparison of large-scale electron beam and bench-scale 60Co irradiations of simulated aqueous waste streams

International Nuclear Information System (INIS)

Kurucz, Charles N.; Waite, Thomas D.; Otano, Suzana E.; Cooper, William J.; Nickelsen, Michael G.

2002-01-01

The effectiveness of using high energy electron beam irradiation for the removal of toxic organic chemicals from water and wastewater has been demonstrated by commercial-scale experiments conducted at the Electron Beam Research Facility (EBRF) located in Miami, Florida and elsewhere. The EBRF treats various waste and water streams up to 450 l min -1 (120 gal min -1 ) with doses up to 8 kilogray (kGy). Many experiments have been conducted by injecting toxic organic compounds into various plant feed streams and measuring the concentrations of compound(s) before and after exposure to the electron beam at various doses. Extensive experimentation has also been performed by dissolving selected chemicals in 22,700 l (6000 gal) tank trucks of potable water to simulate contaminated groundwater, and pumping the resulting solutions through the electron beam. These large-scale experiments, although necessary to demonstrate the commercial viability of the process, require a great deal of time and effort. This paper compares the results of large-scale electron beam irradiations to those obtained from bench-scale irradiations using gamma rays generated by a 60 Co source. Dose constants from exponential contaminant removal models are found to depend on the source of radiation and initial contaminant concentration. Possible reasons for observed differences such as a dose rate effect are discussed. Models for estimating electron beam dose constants from bench-scale gamma experiments are presented. Data used to compare the removal of organic compounds using gamma irradiation and electron beam irradiation are taken from the literature and a series of experiments designed to examine the effects of pH, the presence of turbidity, and initial concentration on the removal of various organic compounds (benzene, toluene, phenol, PCE, TCE and chloroform) from simulated groundwater

Antioxidant and metabolite profiling of North American and neotropical blueberries using LC-TOF-MS and multivariate analyses.

Science.gov (United States)

Ma, Chunhui; Dastmalchi, Keyvan; Flores, Gema; Wu, Shi-Biao; Pedraza-Peñalosa, Paola; Long, Chunlin; Kennelly, Edward J

2013-04-10

There are many neotropical blueberries, and recent studies have shown that some have even stronger antioxidant activity than the well-known edible North American blueberries. Antioxidant marker compounds were predicted by applying multivariate statistics to data from LC-TOF-MS analysis and antioxidant assays of 3 North American blueberry species (Vaccinium corymbosum, Vaccinium angustifolium, and a defined mixture of Vaccinium virgatum with V. corymbosum) and 12 neotropical blueberry species (Anthopterus wardii, Cavendishia grandifolia, Cavendishia isernii, Ceratostema silvicola, Disterigma rimbachii, Macleania coccoloboides, Macleania cordifolia, Macleania rupestris, Satyria boliviana, Sphyrospermum buxifolium, Sphyrospermum cordifolium, and Sphyrospermum ellipticum). Fourteen antioxidant markers were detected, and 12 of these, including 7 anthocyanins, 3 flavonols, 1 hydroxycinnamic acid, and 1 iridoid glycoside, were identified. This application of multivariate analysis to bioactivity and mass data can be used for identification of pharmacologically active natural products and may help to determine which neotropical blueberry species will be prioritized for agricultural development. Also, the compositional differences between North American and neotropical blueberries were determined by chemometric analysis, and 44 marker compounds including 16 anthocyanins, 15 flavonoids, 7 hydroxycinnamic acid derivatives, 5 triterpene glycosides, and 1 iridoid glycoside were identified.

Population structure and reproduction of Deuterodon langei travassos, 1957 (Teleostei, Characidae in a neotropical stream basin from the Atlantic Forest, Southern Brazil

Directory of Open Access Journals (Sweden)

Jean Ricardo Simões Vitule

2008-12-01

Full Text Available Aspects of the biology of D. langei were studied at different sites along a longitudinal gradient formed by the Ribeirão stream basin, a Neotropical stream of the Atlantic Forest, southern Brazil. Differences were observed in population structure and reproduction along the longitudinal gradient and during the study period. Juvenile fishes occurred in high abundance, mainly in the downstream site after the rainy months. Adults occurred mainly in the intermediate and upstream sites. During their life cycle, adults optimise their reproductive strategy by concentrating the reproductive period with total spawn in a short time interval before summer rains dragged the juvenile, larval forms and/or eggs downstream. The downstream site was characterized by a wide range of microhabitats (ex. submerged grass and shallow flooded area. Thus, the species used different portions of the basin in distinct stages of its life, being ecologically adapted to variation patterns in its temporal and physical environments.Aspectos da biologia de D. langei foram estudados em diferentes locais da bacia do rio Ribeirão, um riacho litorâneo da Floresta Atlântica do sudeste do Brasil. Foram observadas diferenças na estrutura da população e na reprodução, ao longo do gradiente longitudinal da bacia e do período de estudo. Os peixes juvenis ocorreram em grande abundância, principalmente no trecho a jusante da bacia, após os meses mais chuvosos. Adultos ocorreram principalmente nos trechos intermediários e a montante. Não houve diferença significativa na relação sexual entre os locais amostrados, estações do ano, meses e classes de comprimento. O comprimento médio de primeira maturação (L50 foi o mesmo para machos e fêmeas, entre 6,1 e 7,0 cm de comprimento total (Lt. O período reprodutivo foi curto (entre o final da primavera e início do verão, antes dos meses mais chuvosos, com desova total. O Índice de Atividade Reprodutiva (IAR indicou que D

Countryside biogeography of Neotropical reptiles and amphibians.

Science.gov (United States)

Mendenhall, Chase D; Frishkoff, Luke O; Santos-Barrera, Georgina; Pacheco, Jesús; Mesfun, Eyobed; Mendoza Quijano, Fernando; Ehrlich, Paul R; Ceballos, Gerardo; Daily, Gretchen C; Pringle, Robert M

2014-04-01

The future of biodiversity and ecosystem services depends largely on the capacity of human-dominated ecosystems to support them, yet this capacity remains largely unknown. Using the framework of countryside biogeography, and working in the Las Cruces system of Coto Brus, Costa Rica, we assessed reptile and amphibian assemblages within four habitats that typify much of the Neotropics: sun coffee plantations (12 sites), pasture (12 sites), remnant forest elements (12 sites), and a larger, contiguous protected forest (3 sites in one forest). Through analysis of 1678 captures of 67 species, we draw four primary conclusions. First, we found that the majority of reptile (60%) and amphibian (70%) species in this study used an array of habitat types, including coffee plantations and actively grazed pastures. Second, we found that coffee plantations and pastures hosted rich, albeit different and less dense, reptile and amphibian biodiversity relative to the 326-ha Las Cruces Forest Reserve and neighboring forest elements. Third, we found that the small ribbons of "countryside forest elements" weaving through farmland collectively increased the effective size of a 326-ha local forest reserve 16-fold for reptiles and 14-fold for amphibians within our 236-km2 study area. Therefore, countryside forest elements, often too small for most remote sensing techniques to identify, are contributing -95% of the available habitat for forest-dependent reptiles and amphibians in our largely human-dominated study region. Fourth, we found large and pond-reproducing amphibians to prefer human-made habitats, whereas small, stream-reproducing, and directly developing species are more dependent on forest elements. Our investigation demonstrates that tropical farming landscapes can support substantial reptile and amphibian biodiversity. Our approach provides a framework for estimating the conservation value of the complex working landscapes that constitute roughly half of the global land surface

Management implications of cowbird parasitism on neotropical migrant songbirds

Science.gov (United States)

Scott K. Robinson; Joseph A. Grzybowski; Stephen I. Rothstein; Margaret C. Brittingham; Lisa J. Petit; Frank R. Thompson

1993-01-01

Populations of brood parasitic Brown-headed Cowbirds (Molofhrus afer) have increased to the point where they pose a potential threat to populations of many neotropical migrant songbirds. Because cowbirds mostly feed in short grass (e.g., pastures and lawns) or on bare ground (e.g., row crops), they benefit directly from human activities. Cowbirds...

The role of indicator species: Neotropical migratory song birds

Science.gov (United States)

Theodore R. Simons; Kerry N. Rabenold; David A. Buehler; Jaime A. Collazo; Kathleen E. Franzreb

1999-01-01

Southern Appalachian forests support some of the richest avian diversity in North America, including some 75 species of Neotropical migrants, birds that perform the remarkable feat of making much of the Western Hemisphere their home. This diverse group includes the swallows, kingbirds, and other flycatchers that feed in the air on flying insects. The Eastern kingbird...

New Neotropical species of Prioninae and Cerambycinae (Cerambycidae)

OpenAIRE

GALILEO, Maria Helena M.; MARTINS, Ubirajara R.

2010-01-01

Novas espécies descritas: Hovorelus adiectus sp. nov. (Anacolini) da Costa Rica; Stenoeme aguilari sp. nov. do Paraguai e Placoeme wappesi sp. nov. da Bolívia (Oemini); da Bahia, Brasil: Coeloxestia spinosa sp. nov. (Cerambycini, Sphallotrichina); Stizocera debilis sp. nov., Anelaphus bravoi sp. nov. (Elaphidionini) e Chydarteres formosus sp. nov. (Trachyderini).New Neotropical species of Prioninae and Cerambycinae (Cerambycidae). New species described: Hovorelus adiectus sp. nov. (Anacolini)...

Molecular phylogeny of Neotropical monogeneans (Platyhelminthes: Monogenea) from catfishes (Siluriformes)

Czech Academy of Sciences Publication Activity Database

Mendoza-Palmero, Carlos Alonso; Blasco-Costa, I.; Scholz, Tomáš

2015-01-01

Roč. 8, MAR 18 2015 (2015), s. 164 ISSN 1756-3305 R&D Projects: GA ČR GBP505/12/G112 Institutional support: RVO:60077344 Keywords : Phylogeny * Monogenea * Dactylogyridae * Neotropical region * Diversity * Siluriformes * 28S rRNA Subject RIV: EG - Zoology Impact factor: 3.234, year: 2015

Rove beetles (Coleoptera Staphylilnidae) in neotropical riverine landscapes: characterising their distribution.

NARCIS (Netherlands)

Gutierrez Chacon, C.; Del Carmen Zuniga, M.; van Bodegom, P.M.; Chara, J.; Giraldo, L.M.

2009-01-01

1. The diversity and ecology of Staphylinidae in the Neotropical region has been poorly investigated, especially in riverine landscapes where these beetles are among the dominant organisms. Therefore, the relation between the occurrence of Staphylinidae and environmental variables was investigated

Environmental and organismal predictors of intraspecific variation in the stoichiometry of a neotropical freshwater fish.

Science.gov (United States)

El-Sabaawi, Rana W; Kohler, Tyler J; Zandoná, Eugenia; Travis, Joseph; Marshall, Michael C; Thomas, Steven A; Reznick, David N; Walsh, Matthew; Gilliam, James F; Pringle, Catherine; Flecker, Alexander S

2012-01-01

The elemental composition of animals, or their organismal stoichiometry, is thought to constrain their contribution to nutrient recycling, their interactions with other animals, and their demographic rates. Factors that affect organismal stoichiometry are generally poorly understood, but likely reflect elemental investments in morphological features and life history traits, acting in concert with the environmental availability of elements. We assessed the relative contribution of organismal traits and environmental variability to the stoichiometry of an insectivorous Neotropical stream fish, Rivulus hartii. We characterized the influence of body size, life history phenotype, stage of maturity, and environmental variability on organismal stoichiometry in 6 streams that differ in a broad suite of environmental variables. The elemental composition of R. hartii was variable, and overlapped with the wide range of elemental composition documented across freshwater fish taxa. Average %P composition was ∼3.2%(±0.6), average %N∼10.7%(±0.9), and average %C∼41.7%(±3.1). Streams were the strongest predictor of organismal stoichiometry, and explained up to 18% of the overall variance. This effect appeared to be largely explained by variability in quality of basal resources such as epilithon N:P and benthic organic matter C:N, along with variability in invertebrate standing stocks, an important food source for R. hartii. Organismal traits were weak predictors of organismal stoichiometry in this species, explaining when combined up to 7% of the overall variance in stoichiometry. Body size was significantly and positively correlated with %P, and negatively with N:P, and C:P, and life history phenotype was significantly correlated with %C, %P, C:P and C:N. Our study suggests that spatial variability in elemental availability is more strongly correlated with organismal stoichiometry than organismal traits, and suggests that the stoichiometry of carnivores may not be

Environmental and organismal predictors of intraspecific variation in the stoichiometry of a neotropical freshwater fish.

Directory of Open Access Journals (Sweden)

Rana W El-Sabaawi

Full Text Available The elemental composition of animals, or their organismal stoichiometry, is thought to constrain their contribution to nutrient recycling, their interactions with other animals, and their demographic rates. Factors that affect organismal stoichiometry are generally poorly understood, but likely reflect elemental investments in morphological features and life history traits, acting in concert with the environmental availability of elements. We assessed the relative contribution of organismal traits and environmental variability to the stoichiometry of an insectivorous Neotropical stream fish, Rivulus hartii. We characterized the influence of body size, life history phenotype, stage of maturity, and environmental variability on organismal stoichiometry in 6 streams that differ in a broad suite of environmental variables. The elemental composition of R. hartii was variable, and overlapped with the wide range of elemental composition documented across freshwater fish taxa. Average %P composition was ∼3.2%(±0.6, average %N∼10.7%(±0.9, and average %C∼41.7%(±3.1. Streams were the strongest predictor of organismal stoichiometry, and explained up to 18% of the overall variance. This effect appeared to be largely explained by variability in quality of basal resources such as epilithon N:P and benthic organic matter C:N, along with variability in invertebrate standing stocks, an important food source for R. hartii. Organismal traits were weak predictors of organismal stoichiometry in this species, explaining when combined up to 7% of the overall variance in stoichiometry. Body size was significantly and positively correlated with %P, and negatively with N:P, and C:P, and life history phenotype was significantly correlated with %C, %P, C:P and C:N. Our study suggests that spatial variability in elemental availability is more strongly correlated with organismal stoichiometry than organismal traits, and suggests that the stoichiometry of carnivores

STREAMS - Technology Programme. Yearbook 2003

International Nuclear Information System (INIS)

2003-01-01

The STREAMS Technology Programme addresses municipal waste. Municipal waste is composed of waste from households and small businesses. The programme focuses on five areas Waste prevention, Collection, transportation, and management of waste streams, Waste treatment technologies, Waste recycling into raw materials and new products, Landfill technologies. The development projects of the STREAMS Programme utilize a number of different technologies, such as biotechnology, information technology, materials technology, measurement and analysis, and automation technology. Finnish expertise in materials recycling technologies and related electronics and information technology is extremely high on a worldwide scale even though the companies represent SMEs. Started in 2001, the STREAMS programme has a total volume of 27 million euros, half of which is funded by Tekes. The programme runs through the end of 2004. (author)

Air-electron stream interactions during magnetic resonance IGRT. Skin irradiation outside the treatment field during accelerated partial breast irradiation

International Nuclear Information System (INIS)

Park, Jong Min; Shin, Kyung Hwan; Wu, Hong-Gyun; Kim, Jung-in; Park, So-Yeon; Kim, Jin Ho; Jeon, Seung Hyuck; Choi, Noorie

2018-01-01

To investigate and to prevent irradiation outside the treatment field caused by an electron stream in the air generated by the magnetic field during magnetic resonance image-guided accelerated partial breast irradiation (APBI). In all, 20 patients who received APBI with a magnetic resonance image-guided radiation therapy (MR-IGRT) system were prospectively studied. The prescription dose was 38.5 Gy in 10 fractions of 3.85 Gy and delivered with a tri-cobalt system (the ViewRay system). For each patient, primary plans were delivered for the first five fractions and modified plans with different gantry angles from those of the primary plan (in-treatment plans) were delivered for the remaining five fractions to reduce the skin dose. A 1 cm thick bolus was placed in front of the patient's jaw, ipsilateral shoulder, and arm to shield them from the electron stream. Radiochromic EBT3 films were attached to the front (towards the breast) and back (towards the head) of the bolus during treatment. Correlations between the measured values and the tumor locations, treatment times, and tumor sizes were investigated. For a single fraction delivery, the average areas of the measured isodoses of 14% (0.54 Gy), 12% (0.46 Gy), and 10% (0.39 Gy) at the front of the boluses were as large as 3, 10.4, and 21.4 cm 2 , respectively, whereas no significant dose could be measured at the back of the boluses. Statistically significant but weak correlations were observed between the measured values and the treatment times. During radiotherapy for breast cancer with an MR-IGRT system, the patient must be shielded from electron streams in the air generated by the interaction of the magnetic field with the beams of the three-cobalt treatment unit to avoid unwanted irradiation of the skin outside the treatment field. (orig.) [de

Energy Efficient Removal of Volatile Organic Compounds (VOCs) and Organic Hazardous Air Pollutants (o-HAPs) from Industrial Waste Streams by Direct Electron Oxidation

Energy Technology Data Exchange (ETDEWEB)

Testoni, A. L.

2011-10-19

This research program investigated and quantified the capability of direct electron beam destruction of volatile organic compounds and organic hazardous air pollutants in model industrial waste streams and calculated the energy savings that would be realized by the widespread adoption of the technology over traditional pollution control methods. Specifically, this research determined the quantity of electron beam dose required to remove 19 of the most important non-halogenated air pollutants from waste streams and constructed a technical and economic model for the implementation of the technology in key industries including petroleum refining, organic & solvent chemical production, food & beverage production, and forest & paper products manufacturing. Energy savings of 75 - 90% and green house gas reductions of 66 - 95% were calculated for the target market segments.

A novel molecular marker for the study of Neotropical cichlid phylogeny.

Science.gov (United States)

Fabrin, T M C; Gasques, L S; Prioli, S M A P; Prioli, A J

2015-12-22

The use of molecular markers has contributed to phylogeny and to the reconstruction of species' evolutionary history. Each region of the genome has different evolution rates, which may or may not identify phylogenetic signal at different levels. Therefore, it is important to assess new molecular markers that can be used for phylogenetic reconstruction. Regions that may be associated with species characteristics and are subject to selective pressure, such as opsin genes, which encode proteins related to the visual system and are widely expressed by Cichlidae family members, are interesting. Our aim was to identify a new nuclear molecular marker that could establish the phylogeny of Neotropical cichlids and is potentially correlated with the visual system. We used Bayesian inference and maximum likelihood analysis to support the use of the nuclear opsin LWS gene in the phylogeny of eight Neotropical cichlid species. Their use concatenated to the mitochondrial gene COI was also tested. The LWS gene fragment comprised the exon 2-4 region, including the introns. The LWS gene provided good support for both analyses up to the genus level, distinguishing the studied species, and when concatenated to the COI gene, there was a good support up to the species level. Another benefit of utilizing this region, is that some polymorphisms are associated with changes in spectral properties of the LWS opsin protein, which constitutes the visual pigment that absorbs red light. Thus, utilization of this gene as a molecular marker to study the phylogeny of Neotropical cichlids is promising.

Stopover ecology of neotropical migrants in central Veracruz, México

Science.gov (United States)

Ernesto Ruelas Inzunza; Stephen W. Hoffman; Laurie J. Goodrich

2005-01-01

Available information on the ecology of neotropical migrants during the winter season and especially during migration is far behind the existing knowledge of birds during the breeding season. This paper presents a stopover ecology case study. We document the occurrence of species, outline the prevailing weather patterns during spring and fall migration seasons, and...

External morphology of the immature stages of Neotropical heliconians: IX. Dione glycera (C. Felder & R. Felder (Lepidoptera, Nymphalidae, Heliconiinae

Directory of Open Access Journals (Sweden)

Héctor A. Vargas

2014-06-01

Full Text Available External morphology of the immature stages of Neotropical heliconians: IX. Dione glycera (C. Felder & R. Felder (Lepidoptera, Nymphalidae, Heliconiinae. The biology of the Andean silverspot butterfly Dione glycera (C. Felder & R. Felder, 1861 is still poorly known. This species is restricted to high elevations in the Andes, where the immature stages are found in close association with species of Passiflora belonging to the section Tacsonia (Juss. Harms, especially P. tripartida var. mollissima (Kunth, which is grown for subsistence by villagers. Herein we describe and illustrate the external features of the egg, larva and pupa of D. glycera, based on light and scanning electron microscopy.

Limits on the streaming and escape of electrons in thermal models for solar hard X-ray emission

International Nuclear Information System (INIS)

Smith, D.F.; Brown, J.C.

1980-01-01

Upper limits on the number of fast electrons streaming through and escaping from a plasma whose electrons have been heated to approx.10 8 K and confined by a collisionless ion-acoustic thermal conduction front are determined. It is shown that such a front is fairly transparent to fast electrons with velocities much larger than the thermal velocity because the anisotropic ion-acoustic waves cannot scatter them, making them collisionless on a scale much larger than the thickness of the front. The collisionless analog of the collisional thermoelectric field is derived self-consistently and shown to offer a significant impediment to fast electrons because they must climb over a large potential barrier than in the collisional case. The only factors limiting the escape of electrons able to surmount this barrier are their rate of production and the requirement that they carry less heat flux than the maximum heat flux allowable. The rate of production is determined for the case of a Maxwellian whose tail is being filled collisionally. Requirements for the stability of these electrons in the hot source plasma and conduction front are given. Methods of refining these limits are discussed

Point Count Length and Detection of Forest Neotropical Migrant Birds

Science.gov (United States)

Deanna K. Dawson; David R. Smith; Chandler S. Robbins

1995-01-01

Comparisons of bird abundances among years or among habitats assume that the rates at which birds are detected and counted are constant within species. We use point count data collected in forests of the Mid-Atlantic states to estimate detection probabilities for Neotropical migrant bird species as a function of count length. For some species, significant differences...

The ecology of migrant birds: A neotropical perspective [book review

Science.gov (United States)

Deborah M. Finch

1998-01-01

Originally published by the U.S. Fish and Wildlife Service in 1983 as Nearctic Avian Migrants in the Neotropics with coauthors Gene Morton, Tom Lovejoy, and Jim Ruos, the initial work has been considerably expanded, updated, and revised by John Rappole. Indeed, the revision warranted publication in Spanish in 1993 followed by further revision that resulted in this...

Solar wind stream interfaces

International Nuclear Information System (INIS)

Gosling, J.T.; Asbridge, J.R.; Bame, S.J.; Feldman, W.C.

1978-01-01

Measurements aboard Imp 6, 7, and 8 reveal that approximately one third of all high-speed solar wind streams observed at 1 AU contain a sharp boundary (of thickness less than approx.4 x 10 4 km) near their leading edge, called a stream interface, which separates plasma of distinctly different properties and origins. Identified as discontinuities across which the density drops abruptly, the proton temperature increases abruptly, and the speed rises, stream interfaces are remarkably similar in character from one stream to the next. A superposed epoch analysis of plasma data has been performed for 23 discontinuous stream interfaces observed during the interval March 1971 through August 1974. Among the results of this analysis are the following: (1) a stream interface separates what was originally thick (i.e., dense) slow gas from what was originally thin (i.e., rare) fast gas; (2) the interface is the site of a discontinuous shear in the solar wind flow in a frame of reference corotating with the sun; (3) stream interfaces occur at speeds less than 450 km s - 1 and close to or at the maximum of the pressure ridge at the leading edges of high-speed streams; (4) a discontinuous rise by approx.40% in electron temperature occurs at the interface; and (5) discontinuous changes (usually rises) in alpha particle abundance and flow speed relative to the protons occur at the interface. Stream interfaces do not generally recur on successive solar rotations, even though the streams in which they are embedded often do. At distances beyond several astronomical units, stream interfaces should be bounded by forward-reverse shock pairs; three of four reverse shocks observed at 1 AU during 1971--1974 were preceded within approx.1 day by stream interfaces. Our observations suggest that many streams close to the sun are bounded on all sides by large radial velocity shears separating rapidly expanding plasma from more slowly expanding plasma

Identification of Plasmodium spp. in Neotropical primates of Maranhense Amazon in Northeast Brazil.

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Mayra Araguaia Pereira Figueiredo

Full Text Available In the Brazilian Amazon region, malaria caused by Plasmodium malariae is considered to be a zoonosis because of cross-transfer of the parasite between humans and Neotropical primates. To contribute information on this issue, we investigated occurrences of natural infection with Plasmodium sp. among Neotropical primates in the Maranhense Amazon (Amazon region of the state of Maranhão, in the northeastern region of Brazil. Blood samples were collected from 161 Neotropical primates of six species that were caught in an environmental reserve (Sítio Aguahy and from captive primates (CETAS-Wildlife Screening Center, municipality of São Luís, in Maranhão. Plasmodium sp. was diagnosed based on light microscopy, PCR, qPCR and LAMP for amplification of the 18S rRNA gene. Serum samples were also assayed by means of indirect immunofluorescence for IgG antibodies against P. malariae/P. brasilianum, P. falciparum and P. berghei. Parasites were detected through light microscopy on five slides from captive primates (four Sapajus spp. and one Callithrix jacchus. In the molecular tests, 34.16% (55/161 and 29.81% (48/161 of the animals sampled were positive in the qPCR and PCR assays, respectively. In the PCR, 47/48 animals were positive for P. malariae/P. brasilianum; of these, eight were free-living primates and 39 from CETAS, São Luís. One sample showed a band in the genus-specific reaction, but not in the second PCR reaction. Anti-P. malariae/P. brasilianum IgG antibodies were detected in four serum samples from Sapajus spp. in captivity. In this study, circulation of P. malariae/P. brasilianum in Neotropical primates was confirmed, with low levels of parasitemia and low levels of antibodies. The importance of these animals as reservoirs of human malaria in the region studied is still unknown. This scenario has an impact on control and elimination of malaria in this region.

WILD BEES (HYMENOPTERA: APOIDEA AS BIOINDICATORS IN THE NEOTROPICS

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Enrique Reyes-Novelo

2008-12-01

Full Text Available The present is a review about the use of wild bees as an indicator group in biodiversity and fragmentation studies. It describes the criteria used for the selection of bioindicator groups and it discusses the available information to evaluate if wild bees meet this criteria. The reviewed information suggests that wild bees comply with the requeriments for a suitable bioindicator group. Its use is recommended for Neotropical ecosystems.

[Spatial and temporal variation in diet composition of invertivore fishes in a tropical stream, Venezuela].

Science.gov (United States)

Ortaz, Mario; Martín, Ricardo; López-Ordaz, Adriana

2011-09-01

Invertivores fishes are an important component of neotropical streams and they represent a link between aquatic invertebrates and piscivorous species. This study evaluated the breadth diet and interspecific food overlap of nine invertivores fish species during three consecutive hydrological phases: falling (December/07, January/08, February/08 and March/08), low (April/08) and rising waters (June/08), in two sections of a Venezuelan neotropical stream, which were located at different elevation, high watershed (HW) and low watershed (LW). The fishes were collected with a beach seine (5mm mesh) between 8:00 and 11:00 hours. The diet of each species was evaluated using an index of relative importance (IRI), which includes as variables the number, weight and occurrence frequency of food items consumed. The Levin' index (B ) and Morisita (IM) were used to estimate the breadth diet and interspecific food overlap, respectively. All estimations were made using the numeric proportion of preys. Nine fish species were captured, eight Characiformes, of which three were captured in HW (Knodus deuteronoides, Creagrutus bolivari and C. melasma) and five in LW (Thoracocharax stellatus, Moenkhausia lepidura, Cheirodon pulcher, Ctenobrycon spilurus and Aphyocharax alburnus), and one Cyprinodontiformes (Poecilia reticulata), which was also found in HW. In HW aquatic insects were the main resource consumed by fishes while plant material and terrestrial arthropods were secondary resources. In LW the fishes ingested all of these items in addition to zooplankton (Copepoda, Cladocera and larval stages of Decapoda). However, there was a temporal replacement with a predominance of zooplankton in falling and low water. In general, the breadth diet decreased during the falling water in both sections and increased in rising water. However, the average breadth diet was higher in HW. The interspecific food overlap was high in HW while low values were more frequent in LW and its temporal

Evidence for the exchange of blood parasites between North America and the Neotropics in blue-winged teal (Anas discors)

Science.gov (United States)

Ramey, Andy M.; Reed, John; Walther, Patrick; Link, Paul; Schmutz, Joel A.; Douglas, David C.; Stallknecht, David E.; Soos, Catherine

2016-01-01

Blue-winged teal (Anas discors) are abundant, small-bodied dabbling ducks that breed throughout the prairies of the northcentral USA and central Canada and that winter in the southern USA and northern Neotropics. Given the migratory tendencies of this species, it is plausible that blue-winged teal may disperse avian pathogens, such as parasites causing avian malaria, between spatially distant areas. To test the hypothesis that blue-winged teal play a role in the exchange of blood parasites between North America and areas further south, we collected information on migratory tendencies of this species and sampled birds at spatially distant areas during breeding and non-breeding periods to diagnose and genetically characterize parasitic infections. Using a combination of band recovery data, satellite telemetry, molecular diagnostics, and genetic analyses, we found evidence for (1) migratory connectivity of blue-winged teal between our sampling locations in the Canadian prairies and along the US Gulf Coast with areas throughout the northern Neotropics, (2) parasite acquisition at both breeding and non-breeding areas, (3) infection of blue-winged teal sampled in Canada and the USA withPlasmodium parasite lineages associated with the Neotropics, and (4) infection of blue-winged teal with parasites that were genetically related to those previously reported in waterfowl in both North America and South America. Collectively, our results suggest that blue-winged teal likely play a role in the dispersal of blood parasites between the Neotropics and North America, and therefore, the targeting of this species in surveillance programs for the early detection of Neotropical-origin avian pathogens in the USA may be informative.

An interactive database for setting conservation priorities for western neotropical migrants

Science.gov (United States)

Michael F. Carter; Keith Barker

1993-01-01

We develop and explain a species ranking system for the states and physiographic regions of the Neotropical Migratory Bird Conservation Program's West Working Group. The ranking criteria attempt to measure characteristics of species which make them vulnerable to extirpation, as well as assess the relative importance of different geographic and/or political areas...

Air-electron stream interactions during magnetic resonance IGRT : Skin irradiation outside the treatment field during accelerated partial breast irradiation.

Science.gov (United States)

Park, Jong Min; Shin, Kyung Hwan; Kim, Jung-In; Park, So-Yeon; Jeon, Seung Hyuck; Choi, Noorie; Kim, Jin Ho; Wu, Hong-Gyun

2018-01-01

To investigate and to prevent irradiation outside the treatment field caused by an electron stream in the air generated by the magnetic field during magnetic resonance image-guided accelerated partial breast irradiation (APBI). In all, 20 patients who received APBI with a magnetic resonance image-guided radiation therapy (MR-IGRT) system were prospectively studied. The prescription dose was 38.5 Gy in 10 fractions of 3.85 Gy and delivered with a tri-cobalt system (the ViewRay system). For each patient, primary plans were delivered for the first five fractions and modified plans with different gantry angles from those of the primary plan (in-treatment plans) were delivered for the remaining five fractions to reduce the skin dose. A 1 cm thick bolus was placed in front of the patient's jaw, ipsilateral shoulder, and arm to shield them from the electron stream. Radiochromic EBT3 films were attached to the front (towards the breast) and back (towards the head) of the bolus during treatment. Correlations between the measured values and the tumor locations, treatment times, and tumor sizes were investigated. For a single fraction delivery, the average areas of the measured isodoses of 14% (0.54 Gy), 12% (0.46 Gy), and 10% (0.39 Gy) at the front of the boluses were as large as 3, 10.4, and 21.4 cm 2 , respectively, whereas no significant dose could be measured at the back of the boluses. Statistically significant but weak correlations were observed between the measured values and the treatment times. During radiotherapy for breast cancer with an MR-IGRT system, the patient must be shielded from electron streams in the air generated by the interaction of the magnetic field with the beams of the three-cobalt treatment unit to avoid unwanted irradiation of the skin outside the treatment field.

Neotropical coastal lagoons: an appraisal of their biodiversity, functioning, threats and conservation management

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FA. Esteves

Full Text Available Neotropical coastal lagoons (NCL are human-dominated ecosystems. Their distribution along densely populated coastal areas of developing countries makes these systems among the most threatened in the world. Here, we summarize some aspects of the causes and consequences of NCL biodiversity, their functioning, their importance to the surrounding populations, their fragility, and their responses to local and global anthropogenic impacts and the challenges that Neotropical countries face in conserving these systems. Although still scarce and geographically concentrated, a growing body of studies has shown that NCLs are physiographically diversified systems, which harbor a considerable and particular proportion of the Neotropical inland aquatic biodiversity. Despite the fact that coastal lagoons are ecotones that are intricately connected to surrounding environments, they develop mechanisms for structural and functional regulation, which confer to these systems higher productivity and carrying capacities than surrounding ecosystems. Such traits attract residential developments and subsidize local traditional populations with important economic and aesthetic ecosystem revenues such as fisheries and scenic beauty. However, the disorganized human occupation around NCLs are causing profound impacts such as eutrophication, salinization, exotic species introduction, as well as other effects, which are ultimately imposing major habitat degradations and biodiversity extirpations in NCLs. We argue that interdisciplinary conservation strategies, which integrate scientific expertise, government officials, private companies and the general public, are the most likely to overcome the geographic and economic obstacles to NCL conservation.

Essential Oils from Neotropical Piper Species and Their Biological Activities

Science.gov (United States)

da Trindade, Rafaela; Alves, Nayara Sabrina; Figueiredo, Pablo Luís; Maia, José Guilherme S.; Setzer, William N.

2017-01-01

The Piper genus is the most representative of the Piperaceae reaching around 2000 species distributed in the pantropical region. In the Neotropics, its species are represented by herbs, shrubs, and lianas, which are used in traditional medicine to prepare teas and infusions. Its essential oils (EOs) present high yield and are chemically constituted by complex mixtures or the predominance of main volatile constituents. The chemical composition of Piper EOs displays interspecific or intraspecific variations, according to the site of collection or seasonality. The main volatile compounds identified in Piper EOs are monoterpenes hydrocarbons, oxygenated monoterpenoids, sesquiterpene hydrocarbons, oxygenated sesquiterpenoids and large amounts of phenylpropanoids. In this review, we are reporting the biological potential of Piper EOs from the Neotropical region. There are many reports of Piper EOs as antimicrobial agents (fungi and bacteria), antiprotozoal (Leishmania spp., Plasmodium spp., and Trypanosoma spp.), acetylcholinesterase inhibitor, antinociceptive, anti-inflammatory and cytotoxic activity against different tumor cells lines (breast, leukemia, melanoma, gastric, among others). These studies can contribute to the rational and economic exploration of Piper species, once they have been identified as potent natural and alternative sources to treat human diseases. PMID:29240662

Different roles of electron beam in two stream instability in an elliptical waveguide for generation and amplification of THz electromagnetic waves

Energy Technology Data Exchange (ETDEWEB)

Safari, S.; Jazi, B., E-mail: jaziada@kashanu.ac.ir [Department of Laser and Photonics, Faculty of Physics, University of Kashan, Kashan, Islamic Republic of Iran (Iran, Islamic Republic of); Jahanbakht, S. [Department of Communications Engineering, Faculty of Electrical And Computer Engineering, University of Kashan, Kashan, Islamic Republic of Iran (Iran, Islamic Republic of)

2016-08-15

In this work, two stream instability in a metallic waveguide with elliptical cross-section and with a hollow annular dielectric layer is studied for generation and amplification of THz electromagnetic waves. Dispersion relation of waves and their dependents to geometric dimensions and characteristics of the electron beam are analyzed. In continuation, the diagrams of growth rate for some operating frequencies are presented, so that effective factors on the growth rates, such as geometrical dimensions, dielectric constant of dielectric layer, accelerating voltage, and applied current intensity are analyzed. It is shown that while an electron beam is responsible for instability, another electron beam plays a stabilizing role.

A taxonomic revision of the Neotropical poison frog genus Ranitomeya (Amphibia: Dendrobatidae)

NARCIS (Netherlands)

Brown, J.L.; Twomey, E.; Amézquita, A.; Souza, M.B.; Caldwell, J.P.; Lötters, S.; May, R.; Melo-Sampaio, P.R.; Mejía-Vargas, D.; Perez-Peña, P.; Pepper, M.; Poelman, E.H.; Sanchez-Rodriguez, M.; Summers, K.

2011-01-01

The Neotropical poison frog genus Ranitomeya is revised, resulting in one new genus, one new species, five synonymies and one species classified as nomen dubium. We present an expanded molecular phylogeny that contains 235 terminals, 104 of which are new to this study. Notable additions to this

Recent origin and rapid speciation of Neotropical orchids in the world's richest plant biodiversity hotspot.

Science.gov (United States)

Pérez-Escobar, Oscar Alejandro; Chomicki, Guillaume; Condamine, Fabien L; Karremans, Adam P; Bogarín, Diego; Matzke, Nicholas J; Silvestro, Daniele; Antonelli, Alexandre

2017-07-01

The Andean mountains of South America are the most species-rich biodiversity hotspot worldwide with c. 15% of the world's plant species, in only 1% of the world's land surface. Orchids are a key element of the Andean flora, and one of the most prominent components of the Neotropical epiphyte diversity, yet very little is known about their origin and diversification. We address this knowledge gap by inferring the biogeographical history and diversification dynamics of the two largest Neotropical orchid groups (Cymbidieae and Pleurothallidinae), using two unparalleled, densely sampled orchid phylogenies (including more than 400 newly generated DNA sequences), comparative phylogenetic methods, geological and biological datasets. We find that the majority of Andean orchid lineages only originated in the last 20-15 million yr. Andean lineages are derived from lowland Amazonian ancestors, with additional contributions from Central America and the Antilles. Species diversification is correlated with Andean orogeny, and multiple migrations and recolonizations across the Andes indicate that mountains do not constrain orchid dispersal over long timescales. Our study sheds new light on the timing and geography of a major Neotropical diversification, and suggests that mountain uplift promotes species diversification across all elevational zones. © 2017 The Authors. New Phytologist © 2017 New Phytologist Trust.

New taxa, including three new genera show uniqueness of Neotropical Nepticulidae (Lepidoptera)

NARCIS (Netherlands)

Nieukerken, van E.J.; Doorenweerd, C.; Nishida, K.; Snyers, C.

2016-01-01

After finding distinct clades in a molecular phylogeny for Nepticulidae that could not be placed in any known genera and discovering clear apomorphic characters that define these clades, as well as a number of Neotropical species that could be placed in known genera but were undescribed, three new

Patterns at Multi-Spatial Scales on Tropical Island Stream Insect Assemblages: Gorgona Island Natural National Park, Colombia, Tropical Eastern Pacific

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Magnolia Longo

2014-02-01

Full Text Available Tropical Eastern Pacific island streams (TEPis differ from other neotropical streams in their rainy climate, mixed sedimentary-volcanic geology and faunal composition. Yet, their relationships between environmental characteristics and stream biota remain unexplored. We analyzed the environmental subject at three spatial scales using a fully nested sampling design (6 streams, 2 reaches within each stream, 2 habitats within each reach, and 4 replicates per habitat on Gorgona Island (Colombia. Sampling was carried out in two months with contrasting rainfall during early 2009. We studied the spatial variation of assemblage composition and density along with 27 independent variables within two contrasting rainfall conditions. Five stream-scale variables, two reach-scale variables, and five habitat-scale variables were selected using a Canonical Correspondence Analysis (CCA. A partial CCA showed that the total variance explained was 13.98%, while stream- and habitat-scale variables explained the highest proportion of the variance (5.74 and 5.01%, respectively. Dissolved oxygen (as affected by rainfall, high-density use zone (a management category, and sedimentary geology were the best descriptors of insect assemblages. The two latter descriptors affected fine-scale variables such as total benthic organic matter and gravel substratum, respectively. A Nested ANOVA showed significant differences in total density and richness among streams and habitats, and significant differences between the two sampling months regardless of the spatial scale. The evenness showed a significant stream- and habitat-dependent temporal variability. These results suggested that rainfall regime in Gorgona Island might be a driver of insect assemblage dynamics mediated by water chemistry and substratum properties. Spatial assemblage variability here is greater within habitats (among samples, and a minor fraction occurs at habitat- and stream-scales, while no longitudinal

DNA barcoding and morphological identification of neotropical ichthyoplankton from the Upper Paraná and São Francisco.

Science.gov (United States)

Becker, R A; Sales, N G; Santos, G M; Santos, G B; Carvalho, D C

2015-07-01

The identification of fish larvae from two neotropical hydrographic basins using traditional morphological taxonomy and DNA barcoding revealed no conflicting results between the morphological and barcode identification of larvae. A lower rate (25%) of correct morphological identification of eggs as belonging to migratory or non-migratory species was achieved. Accurate identification of ichthyoplankton by DNA barcoding is an important tool for fish reproductive behaviour studies, correct estimation of biodiversity by detecting eggs from rare species, as well as defining environmental and management strategies for fish conservation in the neotropics. © 2015 The Fisheries Society of the British Isles.

Effects of livestock grazing on neotropical migratory landbirds in western North America

Science.gov (United States)

Carl E. Bock; Victoria A. Saab; Terrell D. Rich; David S. Dobkin

1993-01-01

Livestock grazing is a widespread and important influence on neotropical migratory birds in four major ecosystems in western North America: grasslands of the Great Plains and Southwest, riparian woodlands, Intermountain shrubsteppe, and open coniferous forests. We have reviewed available literature on avian responses to grazing in these habitats. Among 35 plains...

Environment and Spatial Influences on Aquatic Insect Communities in Cerrado Streams: the Relative Importance of Conductivity, Altitude, and Conservation Areas.

Science.gov (United States)

Godoy, B S; Queiroz, L L; Lodi, S; Oliveira, L G

2017-04-01

The aquatic insect community is an important element for stream functionality and diversity, but the effects of altitude and conservation areas on the aquatic insect community have been poorly explored in neotropical ecozone. The lack of studies about the relative importance of space and environment on community structure is another obstacle within aquatic insect ecology, which precludes the inclusion of these studies in more current frameworks, like the metacommunity dynamics. We evaluated the relationship between the aquatic insect community structure at 19 streams in the Brazilian Cerrado and spatial and environmental variables, namely geographical distance among sites, stream altitude, chemical variables, and environmental protection areas. We partitioned the variance explained by spatial and environmental components using a partial redundancy analysis. The environment exhibited a strong spatial structure for abundance and number of genera, increasing these community parameters with elevated water conductivity. Only community composition had a large unexplained portion of variance, with a small portion constrained by environmental (altitude and conductivity) and spatial factors. A relevant point in the result was the streams with high conductivity were located outside of the conservation areas. These results suggest that the relationship between number of genera and abundance with environmental conditions is always associated with spatial configuration of streams. Our study shows that altitude is an important determinant of community structure, as it exerts indirect influences, and electrical conductivity directly determines community composition, and that some national parks may be inefficient in maintaining the diversity of aquatic insects in the Cerrado region.

Large-scale phylogeography of the disjunct Neotropical tree species Schizolobium parahyba (Fabaceae-Caesalpinioideae).

Science.gov (United States)

Turchetto-Zolet, Andreia C; Cruz, Fernanda; Vendramin, Giovanni G; Simon, Marcelo F; Salgueiro, Fabiano; Margis-Pinheiro, Marcia; Margis, Rogerio

2012-10-01

Neotropical rainforests exhibit high levels of endemism and diversity. Although the evolutionary genetics of plant diversification has garnered increased interest, phylogeographic studies of widely distributed species remain scarce. Here we describe chloroplast and nuclear variation patterns in Schizolobium parahyba (Fabaceae), a widespread tree in Neotropical rainforests that harbor two varieties with a disjunct distribution. Chloroplast and nuclear sequence analyses yielded 21 and 4 haplotypes, respectively. Two genetic diversity centers that correlate with the two known varieties were identified: the Southeastern Atlantic forest and the Amazonian basin. In contrast, the populations from southern and northeastern Atlantic forests and Andean-Central American forests exhibited low levels of genetic diversity and divergent haplotypes, likely related to historical processes that impact the flora and fauna in these regions, such as a founder's effect after dispersion and demographic expansion. Phylogeographic and demographic patterns suggest that episodes of genetic isolation and dispersal events have shaped the evolutionary history for this species, and different patterns have guided the evolution of S. parahyba. Moreover, the results of this study suggest that the dry corridor formed by Cerrado and Caatinga ecoregions and the Andean uplift acted as barriers to this species' gene flow, a picture that may be generalized to most of the plant biodiversity tropical woodlands and forests. These results also reinforce the importance of evaluating multiple genetic markers for a more comprehensive understanding of population structure and history. Our results provide insight into the conservation efforts and ongoing work on the genetics of population divergence and speciation in these Neotropical rainforests. Copyright © 2012 Elsevier Inc. All rights reserved.

Revision and cladistics of the Neotropical genus Pseudoptilolepis Snyder (Diptera, Muscidae Revisão e cladística do gênero neotropical Pseudoptilolepis Snyder (Diptera, Muscidae

Directory of Open Access Journals (Sweden)

Guilherme Schnell e Schuehli

2005-03-01

Full Text Available Pseudoptilolepis Snyder, 1949, a monophyletic Neotropical muscid genus of six species, is reviewed to include four new species, P. centralis sp. nov., P. chrysella sp. nov., P. crocina sp. nov. and P. elbida sp. nov. A taxonomic key is provided for the genus. The phylogenetic relationship among the studied species is: (P. centralis ((P. chrysella (P. fluminensis, P. fulvapoda (P. nudapleura (P. elbida (P. nigripoda, P. crocina. The geographic distribution of the species is also presented and briefly discussed.O gênero Neotropical monofilético Pseudoptilolepis Snyder, 1949 é revisado para a inclusão de quatro espécies novas, P. centralis sp. nov., P. chrysella sp. nov., P. crocina sp. nov. and P. elbida sp. nov. Uma chave taxonômica para o gênero é fornecida. A relação filogenética entre as espécies estudadas é: (P. centralis ((P. chrysella (P. fluminensis, P. fulvapoda (P. nudapleura (P. elbida (P. nigripoda, P. crocina. A distribuição geográfica das espécies é também apresentada e brevemente discutida.

An accurate analysis for guaranteed performance of multiprocessor streaming applications

NARCIS (Netherlands)

Poplavko, P.

2008-01-01

Already for more than a decade, consumer electronic devices have been available for entertainment, educational, or telecommunication tasks based on multimedia streaming applications, i.e., applications that process streams of audio and video samples in digital form. Multimedia capabilities are

The origin and distribution of neotropical species of Campylopus

OpenAIRE

Frahm, Jan-Peter

1990-01-01

Of the 65 species of Campylopus known from tropical America, 33 are andine in distribution, 16 are found only in SE Brazil, 8 have wide ranges through Central and South America, 3 species are disjunct in SE-North America and Brazil, 3 are confined to the Caribbean and one species belongs to the circum-pacific and one to the tethyan element. For different parts of the Neotropics, the composition of phytogeographical elements is calculated. For the first time, bryophyte distributions are compar...

Streaming instability in a velocity–sheared dusty plasma | Duwa ...

African Journals Online (AJOL)

A two-stream instability, obtained from kinetic theory, of strongly velocity-sheared inhomogeneous streaming electron in a magnetized plasma in the presence of negatively charged dust is discussed. Various cold plasma approximations were considered and it is shown that when the diamagnetic effect of ion can be ignored ...

The species of the Neotropical genus Fractipons Townes, 1970 (Hymenoptera, Ichneumonidae, Cryptinae).

Science.gov (United States)

Bordera, Santiago; González-Moreno, Alejandra

2011-01-19

In this paper, two new species of the Neotropical genus Fractipons Townes, 1970 (Hymenoptera, Ichneumonidae) are described. A new diagnosis for the genus, a re-description of Fractipons cincticornis Townes, 1970 and a key to known species are provided. New distribution records for the genus now include Argentina, Costa Rica, Panama and Peru.

Notes on Neotropical Eumeninae, with the description of a new species of Pachodynerus de Saussure (Hymenoptera, Vespidae

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Marcel Gustavo Hermes

2013-06-01

Full Text Available Notes on Neotropical Eumeninae, with the description of a new species of Pachodynerus de Saussure (Hymenoptera, Vespidae. Taxonomic information on Neotropical Eumeninae is provided. A new species, Pachodynerus fessatus sp. nov. is described from southeastern São Paulo, Brazil. Additional material of Pachodynerus sericeus (Fox was examined, representing the first further specimens after the original description and including the previously unknown male. The examination of new material of the genus Stenonartonia adds some new distribution records and shows some previously unrecorded individual variation for some species. The males of Stenonartonia guaraya Garcete-Barrett and Stenonartonia rejectoides Garcete-Barrett are described for the first time.

Two-stream instability in pulsar magnetospheres

International Nuclear Information System (INIS)

Usov, V.V.

1987-01-01

If the electron-positron plasma flow from the pulsar environment is stationary, the two-stream instability does not have enough time to develop in the pulsar magnetosphere. In that case the outflowing electron-positron plasma gathers into separate clouds. The clouds move along magnetic field lines and disperse as they go farther from the pulsar. At a distance of about 10 to the 8th cm from the pulsar surface, the high-energy particles of a given cloud catch up with the low-energy particles that belong to the cloud going ahead of it. In this region of a pulsar magnetosphere, the energy distribution of plasma particles is two-humped, and a two-stream instability may develop. The growth rate of the instability is quite sufficient for its development. 17 references

New taxa, including three new genera show uniqueness of Neotropical Nepticulidae (Lepidoptera

Directory of Open Access Journals (Sweden)

Erik van Nieukerken

2016-10-01

Full Text Available After finding distinct clades in a molecular phylogeny for Nepticulidae that could not be placed in any known genera and discovering clear apomorphic characters that define these clades, as well as a number of Neotropical species that could be placed in known genera but were undescribed, three new genera and nine new species are here described from the Neotropics: Stigmella gallicola van Nieukerken & Nishida, sp. n. reared from galls on Hampea appendiculata (Malvaceae in Costa Rica, representing the first example of a gall making Stigmella; S. schinivora van Nieukerken, sp. n. reared from leafmines on Schinus terebinthifolia (Anacardiaceae in Argentina, Misiones; S. costaricensis van Nieukerken & Nishida, sp. n. and S. intronia van Nieukerken & Nishida, sp. n. each from a single specimen collected the same night in Costa Rica, Parque Nacional Chirripó; S. molinensis van Nieukerken & Snyers, sp. n. reared from leafmines on Salix humboldtiana, Peru, Lima, the first Neotropical species of the Stigmella salicis group sensu stricto; Ozadelpha van Nieukerken, gen. n. with type species O. conostegiae van Nieukerken & Nishida, sp. n., reared from leafmines on Conostegia oerstediana (Melastomataceae from Costa Rica; Neotrifurcula van Nieukerken, gen. n. with type species N. gielisorum van Nieukerken, sp. n. from Chile; Hesperolyra van Nieukerken, gen. n.. with type species Fomoria diskusi Puplesis & Robinson, 2000; Hesperolyra saopaulensis van Nieukerken, sp. n., reared from an unidentified Myrtaceae, Sao Paulo, Brasil; and Acalyptris janzeni van Nieukerken & Nishida, sp. n. from Costa Rica, Guanacaste. Five new combinations are made: Ozadelpha ovata (Puplesis & Robinson, 2000, comb. n. and Ozadelpha guajavae (Puplesis & Diškus, 2002, comb. n., Hesperolyra diskusi (Puplesis & Robinson, 2000, comb. n., Hesperolyra molybditis (Zeller, 1877, comb. n. and Hesperolyra repanda (Puplesis & Diškus, 2002, comb. n. Three specimens are briefly described, but

New taxa, including three new genera show uniqueness of Neotropical Nepticulidae (Lepidoptera)

Science.gov (United States)

van Nieukerken, Erik J.; Doorenweerd, Camiel; Nishida, Kenji; Snyers, Chris

2016-01-01

Abstract After finding distinct clades in a molecular phylogeny for Nepticulidae that could not be placed in any known genera and discovering clear apomorphic characters that define these clades, as well as a number of Neotropical species that could be placed in known genera but were undescribed, three new genera and nine new species are here described from the Neotropics: Stigmella gallicola van Nieukerken & Nishida, sp. n. reared from galls on Hampea appendiculata (Malvaceae) in Costa Rica, representing the first example of a gall making Stigmella; Stigmella schinivora van Nieukerken, sp. n. reared from leafmines on Schinus terebinthifolia (Anacardiaceae) in Argentina, Misiones; Stigmella costaricensis van Nieukerken & Nishida, sp. n. and Stigmella intronia van Nieukerken & Nishida, sp. n. each from a single specimen collected the same night in Costa Rica, Parque Nacional Chirripó; Stigmella molinensis van Nieukerken & Snyers, sp. n. reared from leafmines on Salix humboldtiana, Peru, Lima, the first Neotropical species of the Stigmella salicis group sensu stricto; Ozadelpha van Nieukerken, gen. n. with type species Ozadelpha conostegiae van Nieukerken & Nishida, sp. n., reared from leafmines on Conostegia oerstediana (Melastomataceae) from Costa Rica; Neotrifurcula van Nieukerken, gen. n. with type species Neotrifurcula gielisorum van Nieukerken, sp. n. from Chile; Hesperolyra van Nieukerken, gen. n.. with type species Fomoria diskusi Puplesis & Robinson, 2000; Hesperolyra saopaulensis van Nieukerken, sp. n., reared from an unidentified Myrtaceae, Sao Paulo, Brasil; and Acalyptris janzeni van Nieukerken & Nishida, sp. n. from Costa Rica, Guanacaste. Five new combinations are made: Ozadelpha ovata (Puplesis & Robinson, 2000), comb. n. and Ozadelpha guajavae (Puplesis & Diškus, 2002), comb. n., Hesperolyra diskusi (Puplesis & Robinson, 2000), comb. n., Hesperolyra molybditis (Zeller, 1877), comb. n. and Hesperolyra repanda (Puplesis & Diškus, 2002), comb. n

Characteristics of plasma streams and optimization of operational regimes for magnetoplasma compressor

International Nuclear Information System (INIS)

Bandura, A.N.; Byrka, O.V.; Garkusha, I.E.; Ladygina, M.S.; Marchenko, A.K.; Petrov, Yu.V.; Solyakov, D.G.; Chebotarev, V.V.; Chuvilo, A.A.

2011-01-01

The main objective of these studies is characterization of dense xenon plasma streams generated by magnetoplasma compressor (MPC) in different operational regimes. Optimization of plasma compression in MPC allows increase of the plasma stream pressure up to 22...25 bar, average temperature of electrons of 10...20 eV and plasma stream velocity varied in the range of (2...9)x10 6 cm/s depending on operation regime. Spectroscopy measurements demonstrate that in these conditions most of Xe spectral lines are reabsorbed. In the case of known optical thickness, the real value of electron density can be calculated with accounting self-absorption. Estimations of optical thickness were performed and resulting electron density in focus region was evaluated as 10 18 cm -3 .

Microsatellite Loci for Orthophytum ophiuroides (Bromelioideae, Bromeliaceae Species Adapted to Neotropical Rock Outcrops

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Felipe Aoki-Gonçalves

2014-03-01

Full Text Available Premise of the study: Microsatellite primers were developed for Orthophytum ophiuroides, a rupicolous bromeliad species endemic to neotropical rocky fields. These microsatellite loci will be used to investigate population differentiation and species cohesion in such fragmented environments. The loci were tested for cross-amplification in related bromeliad species. Methods and Results: Eleven polymorphic microsatellite markers were isolated and characterized from an enriched library of O. ophiuroides. The loci were tested on 42 individuals from two populations of this species. The number of alleles per locus ranged from three to nine and the expected and observed heterozygosities ranged from 0.167 to 0.870 and from 0.369 to 0.958, respectively. Seven loci successfully amplified in other related bromeliad species. Conclusions: Our results suggest that the microsatellite loci developed here will be useful to assess genetic diversity and gene flow in O. ophiuroides for the investigation of population differentiation and species cohesion in neotropical mountainous habitats.

Descriptions of two new species of Sphenorhina (Hemiptera, Cercopidae, Tomaspidinae from the Neotropical region

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Andressa Paladini

2013-06-01

Full Text Available Description of two new species of Sphenorhina (Hemiptera, Cercopidae, Tomaspidinae from the Neotropical region. Two new species of Sphenorhina Amyot & Serville, S. pseudoboliviana SP. NOV: from Bolivia and S. plata SP. NOV: from Argentina are described and illustrated.

Range expansion of the invasive insect Greenidea (Trichosiphon) psidii (Hemiptera: Aphididae) in the Neotropical Region.

Science.gov (United States)

Culik, M P; Ventura, J A; Dos S Martins, D

2016-01-01

Greenidea psidii is an invasive insect from Asia that feeds on a diverse variety of agriculturally and environmentally important plant species. As an essential component of research necessary for development of a better understanding of biodiversity and its conservation, this study documents a major recent expansion in range of G. psidii in the Neotropics to the region of the tropical restinga ecosystem of Brazil, where it was found infesting guava (Psidium guajava) and jabuticaba (Plinia cauliflora). A summary of information on the geographic distribution, host plants, identification, and potential natural enemies of G. psidii that may be useful for integrated management of this pest in the Neotropical Region and other areas where this invasive insect has recently become established and is likely to further spread is also provided.

Insecticidal defenses of Piperaceae from the neotropics.

Science.gov (United States)

Bernard, C B; Krishanmurty, H G; Chauret, D; Durst, T; Philogène, B J; Sánchez-Vindas, P; Hasbun, C; Poveda, L; San Román, L; Arnason, J T

1995-06-01

Insecticidal and growth-reducing properties of extracts of 14 species of American neotropical Piperaceae were investigated by inclusion in diets of a polyphagous lepidopteran, the European corn borer,Ostrinia nubilalis. Nutritional indices suggested most extracts acted by postdigestive toxicity.Piper aduncum, P. tuberculatum, andP. decurrens were among the most active species and were subjected to bioassay-guided isolation of the active components. Dillapiol was isolated from the active fraction ofP. aduncum, piperlonguminine was isolated fromP. tuberculatum, and a novel neolignan fromP. decurrens. The results support other studies on Asian and AfricanPiper species, which suggest that lignans and isobutyl amides are the active defence compounds in this family.

Angular distributions of atomic vapor stream produced by electron beam heating

International Nuclear Information System (INIS)

Ohba, Hironori; Amekawa, Kazuhiro; Shibata, Takemasa

1997-03-01

The angular distributions were measured as a function of deposition rate for aluminium, copper, gadolinium and cerium vapor stream produced by an electron beam gun with water-cooled copper crucible. The distributions were recorded on the mounted on a semicircular (120mm in radius) mask over the evaporation source. The measured distributions were able to be described by a simple cosine law, that is cos n θ, except for the case of extremely high evaporation rate with a porous material, where n is a rate-dependent beaming exponent, θ is the angle from the vertical. For many kinds of evaporants, it was confirmed that the beaming exponents increase continuously from unity to 3 or 4 with increasing deposition rate and are approximately proportional to R 0.25 where R is the deposition rate. Moreover, it was found that the beaming exponents n are able to be expressed as n = α Kn 0 -0.25 , where Kn 0 -1 is the inverse of Knudsen number, which is defined by the mean free path of evaporated atoms and the evaporation spot size, and α is the constant. (author)

Angular distributions of atomic vapor stream produced by electron beam heating

Energy Technology Data Exchange (ETDEWEB)

Ohba, Hironori; Amekawa, Kazuhiro; Shibata, Takemasa [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

1997-03-01

The angular distributions were measured as a function of deposition rate for aluminium, copper, gadolinium and cerium vapor stream produced by an electron beam gun with water-cooled copper crucible. The distributions were recorded on the mounted on a semicircular (120mm in radius) mask over the evaporation source. The measured distributions were able to be described by a simple cosine law, that is cos{sup n} {theta}, except for the case of extremely high evaporation rate with a porous material, where n is a rate-dependent beaming exponent, {theta} is the angle from the vertical. For many kinds of evaporants, it was confirmed that the beaming exponents increase continuously from unity to 3 or 4 with increasing deposition rate and are approximately proportional to R{sup 0.25} where R is the deposition rate. Moreover, it was found that the beaming exponents n are able to be expressed as n = {alpha} Kn{sub 0}{sup -0.25}, where Kn{sub 0}{sup -1} is the inverse of Knudsen number, which is defined by the mean free path of evaporated atoms and the evaporation spot size, and {alpha} is the constant. (author)

H(+) - O(+) two-stream interaction on auroral field lines

International Nuclear Information System (INIS)

Bergmann, R.

1990-01-01

Upflowing beams of hydrogen, oxygen, and minor ion species, and downward accelerated electrons have been observed above several thousand kilometers altitude on evening auroral field lines. The mechanism for electron and ion acceleration is generally accepted to be the presence of a quasi-static electric field with a component parallel to the earth's magnetic field. The thermal energy of the observed beams is much larger than ionospheric ion temperatures indicating that the beams have been heated as they are accelerated upward. This heating is probably due to a two-stream interaction between beams of different mass ions. The beams gain equal energy in the potential drop and so have different average velocities. Their relative streaming initiates an ion-ion two-stream interaction which then mediates a transfer of energy and momentum between the beams and causes thermalization of each beam. The qualitative evidence that supports this scenario is reviewed. Properties of the two-stream instability are presented in order to demonstrate that a calculation of the evolution of ion beams requires a model that includes field-aligned spatial structure. 26 refs

Megamitochondria in the serous acinar cells of the submandibular gland of the neotropical fruit bat, Artibeus obscurus.

Science.gov (United States)

Tandler, B; Nagato, T; Phillips, C J

1997-05-01

As part of a continuing investigation of the comparative ultrastructure of chiropteran salivary glands, we examined the submandibular glands of eight species of neotropical fruit bats in the genus Artibeus. We previously described secretory granules of unusual substructure in the seromucous demilunar cells of this organ in some species in this genus. In the present study, we turned our attention to the serous acinar cells in the same glands. Specimens of eight species of Artibeus were collected in neotropical localities. Salivary glands were extirpated in the field and thin slices were fixed by immersion in triple aldehyde-DMSO or in modified half-strength Karnovsky's fixative. Tissues were further processed for electron microscopy by conventional means. In contrast to seromucous cells, which exhibit species-specific diversification in bats of this genus, the secretory apparatus and secretory granules in the serous acinar cells are highly conserved across all seven species. The single exception involves the mitochondria in one species. In this instance, some of the serous cell mitochondria in Artibeus obscurus are modified into megamitochondria. Such organelles usually have short, peripheral cristae; a laminar inclusion is present in the matrix compartment of every outsized organelle. Inclusions of this nature never are present in normal-size mitochondria in the serous cells. None of the megamitochondria were observed in the process of degeneration. The giant mitochondria in A. obscurus have a matrical structure that is radically different from that of the only other megamitochondria reported to occur in bat salivary glands. The factors that lead to variation in megamitochondrial substructure in different species, as well as the functional capacities of such giant organelles, are unknown.

On forecasting ionospheric total electron content responses to high-speed solar wind streams

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Meng Xing

2016-01-01

Full Text Available Conditions in the ionosphere have become increasingly important to forecast, since more and more spaceborne and ground-based technological systems rely on ionospheric weather. Here we explore the feasibility of ionospheric forecasts with the current generation of physics-based models. In particular, we focus on total electron content (TEC predictions using the Global Ionosphere-Thermosphere Model (GITM. Simulations are configured in a forecast mode and performed for four typical high-speed-stream events during 2007–2012. The simulated TECs are quantified through a metric, which divides the globe into a number of local regions and robustly differentiates between quiet and disturbed periods. Proposed forecast products are hourly global maps color-coded by the TEC disturbance level of each local region. To assess the forecasts, we compare the simulated TEC disturbances with global TEC maps derived from Global Positioning System (GPS satellite observations. The forecast performance is found to be merely acceptable, with a large number of regions where the observed variations are not captured by the simulations. Examples of model-data agreements and disagreements are investigated in detail, aiming to understand the model behavior and improve future forecasts. For one event, we identify two adjacent regions with similar TEC observations but significant differences in how local chemistry versus plasma transport contribute to electron density changes in the simulation. Suggestions for further analysis are described.

Floral structure in the neotropical palm genus Chamaedorea (Arecoideae, Arecaceae

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Stauffer, Fred W.

2008-12-01

Full Text Available Male and female floral structure has been studied in 28 species of Chamaedorea, the largest palm genus present in the Neotropics. The taxa investigated represent all subgenera according to the most recent taxonomic revision of the group. Morphological, histological and cytological features that are known to be of importance for interactions with visiting insects were studied and their putative role in protecting the flowering parts assessed. The taxonomic distribution of selected characters is in some cases congruent with relationships inferred by recently published molecular studies within the group.Se ha estudiado la estructura de las flores masculinas y femeninas en 28 especies de Chamaedorea, el género de palmas con mayor número de especies en la región neotropical. Los táxones investigados representan a todos los subgéneros contemplados en la más reciente revisión taxonómica del grupo. Se han estudiado los caracteres morfológicos, histológicos y citológicos de mayor importancia en cuanto a la visita de insectos y se ha examinado su rol dentro de la protección de los órganos florales. La distribución taxonómica de caracteres seleccionados ha demostrado, en algunos casos, ser congruente con las relaciones inferidas por los más recientes estudios moleculares que incluyen al grupo.

Electron cyclotron resonance ion stream etching of tantalum for x-ray mask absorber

International Nuclear Information System (INIS)

Oda, Masatoshi; Ozawa, Akira; Yoshihara, Hideo

1993-01-01

Electron cyclotron resonance ion stream etching of Ta film was investigated for preparing x-ray mask absorber patterns. Ta is etched by the system at a high rate and with high selectivity. Using Cl 2 as etching gas, the etch rate decreases rapidly with decreasing pattern width below 0.5 μm and large undercutting is observed. The problems are reduced by adding Ar or O 2 gas to the Cl 2 . Etching with a mixture of Cl 2 and O 2 produces highly accurate Ta absorber patterns for x-ray masks. The pattern width dependence of the etch rate and the undercutting were simulated with a model that takes account of the angular distribution of active species incident on the sample. The experimental results agree well with those calculated assuming that the incidence angles are distributed between -36 degrees and 36 degrees. The addition of O 2 or Ar enhances ion assisted etching. 16 refs., 16 figs

Reservoirs and human well being: new challenges for evaluating impacts and benefits in the neotropics

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JG. Tundisi

Full Text Available As in many other continents, neotropical ecosystems are impacted by the construction of reservoirs. These artificial ecosystems change considerably the natural terrestrial and aquatic ecosystems and their biodiversity. The multiple uses of reservoirs promote benefits for the human beings in terms of economic development, income, jobs and employment. Services of reservoirs are important assets for the regional ecosystem. Evaluation of ecosystem services produced by artificial reservoirs, are new challenges to the understanding of the cost/benefit relationships of reservoir construction in the neotropics. Regulating and other services promoted by reservoirs lead to new trends for "green technology" and the implementation of ecohydrological and ecotechnological developments. This approach can be utilized with better success as a substitute for the usual impact/benefit evaluation of the reservoirs. Better and diversified services can be achieved with "green technology" applied to the construction.

Delimitation of some neotropical laccate Ganoderma (Ganodermataceae): molecular phylogeny and morphology.

Science.gov (United States)

De Lima Júnior, Nelson Correia; Baptista Gibertone, Tatiana; Malosso, Elaine

2014-09-01

Ganoderma includes species of great economic and ecological importance, but taxonomists judge the current nomenclatural situation as chaotic and poorly studied in the neotropics. From this perspective, phylogenetic analyses inferred from ribosomal DNA sequences have aided the clarification of the genus status. In this study, 14 specimens of Ganoderma and two of Tomophagus collected in Brazil were used for DNA extraction, amplification and sequencing of the ITS and LSU regions (rDNA). The phylogenetic delimitation of six neotropical taxa (G. chalceum, G. multiplicatum, G. orbiforme, G. parvulum, G. aff. oerstedtii and Tomophagus colossus) was determined based on these Brazilian specimens and found to be distinct from the laccate Ganoderma from Asia, Europe, North America and from some specimens from Argentina. Phylogenetic reconstructions confirmed that the laccate Ganoderna is distinct from Tomophagus, although they belong to the same group. The use of taxonomic synonyms Ganoderma subamboinense for G. multiplicatumnz, G. boninense for G. orbiforme and G. chalceum for G. cupreum was not confirmed. However, Ganoderma parvulum was confirmed as the correct name for specimens called G. stipitatu. Furthermore, the name G. hucidumn should be used only for European species. The use of valid published names is proposed according to the specimen geographical distribution, their morphological characteristics and rDNA analysis. 1208. Epub 2014 September 01.

Revisiting adaptations of neotropical katydids (Orthoptera: Tettigoniidae) to gleaning bat predation.

Science.gov (United States)

Ter Hofstede, Hannah; Voigt-Heucke, Silke; Lang, Alexander; Römer, Heinrich; Page, Rachel; Faure, Paul; Dechmann, Dina

2017-01-01

All animals have defenses against predators, but assessing the effectiveness of such traits is challenging. Neotropical katydids (Orthoptera: Tettigoniidae) are an abundant, ubiquitous, and diverse group of large insects eaten by a variety of predators, including substrate-gleaning bats. Gleaning bats capture food from surfaces and usually use prey-generated sounds to detect and locate prey. A number of Neotropical katydid signaling traits, such as the emission of ultrasonic frequencies, substrate vibration communication, infrequent calling, and ultrasound-evoked song cessation are thought to have evolved as defenses against substrate-gleaning bats. We collected insect remains from hairy big-eared bat ( Micronycteris hirsuta ) roosts in Panama. We identified insect remains to order, species, or genus and quantified the proportion of prey with defenses against predatory bats based on defenses described in the literature. Most remains were from katydids and half of those were from species with documented defenses against substrate-gleaning bats. Many culled remains were from insects that do not emit mate-calling songs (e.g. beetles, dragonflies, cockroaches, and female katydids), indicating that eavesdropping on prey signals is not the only prey-finding strategy used by this bat. Our results show that substrate-gleaning bats can occasionally overcome katydid defenses.

Streams with Strahler Stream Order

Data.gov (United States)

Minnesota Department of Natural Resources — Stream segments with Strahler stream order values assigned. As of 01/08/08 the linework is from the DNR24K stream coverages and will not match the updated...

Immune-related effects from predation risk in Neotropical blue-black grassquits (Volatinia jacarina).

Science.gov (United States)

Caetano, João V O; Maia, Maya R; Manica, Lilian T; Macedo, Regina H

2014-11-01

Predation is a major force shaping natural history traits of birds because of their vulnerability during nesting and higher visibility during diurnal activities. For most birds in the Neotropics, predation is the major cause of nest failure due to the region's high diversity and abundance of predators. The blue-black grassquit (Volatinia jacarina), similarly to other small passerines in the savanna region of central Brazil, suffers extremely high rates of nest predation. Additionally, males may be particularly vulnerable to predators since they are very conspicuous when executing courtship displays. We assessed some of the non-lethal costs of predation risk on this species by comparing physiological and morphological parameters of birds exposed to predator vocalizations with that of control subjects exposed to non-predator vocalizations. Birds exposed to the predator vocalizations exhibited an immune-related reaction (changes in their H/L ratio), but no changes were observed in other biological parameters measured. This article is part of a Special Issue entitled: Neotropical Behaviour. Copyright © 2014 Elsevier B.V. All rights reserved.

DVD Based Electronic Pulser

International Nuclear Information System (INIS)

Morris, Scott J.; Pratt, Rick M.; Hughes, Michael A.; Kouzes, Richard T.; Pitts, W K.; Robinson, Eric E.

2005-01-01

This paper describes the design, construction, and testing of a DVD based electronic pulser system (DVDEPS). Such a device is used to generate pulse streams for simulation of both gamma and neutron detector systems. The DVDEPS reproduces a random pulse stream of a full HPGe spectrum as well as a digital pulse stream representing the output of a neutron multiplicity detector. The exchangeable DVD media contains over an hour of data for both detector systems and can contain an arbitrary gamma spectrum and neutron pulse stream. The data is written to the DVD using a desktop computer program from either actual or simulated spectra. The targeted use of the DVDEPS is authentication or validation of monitoring equipment for non-proliferation purposes, but it is also of general use whenever a complex data stream is required. The DVD based pulser combines the storage capacity and simplicity of DVD technology with commonly available electronic components to build a relatively inexpensive yet highly capable testing instrument

Interspecific competition, predation, and the coexistence of three closely related neotropical armoured catfishes (Siluriformes - Callichthyidae)

NARCIS (Netherlands)

Mol, J.H.A.

1995-01-01

Tropical ecosystems are renowned for their high biodiversity with many closely related species living together. Alpha diversity of tropical freshwater fishes is also extremely high, as exemplified by the cichlid fauna of the Great African lakes and the neotropical characins. Since

Results of the global conservation assessment of the freshwater crabs (Brachyura, Pseudothelphusidae and Trichodactylidae: The Neotropical region, with an update on diversity

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Neil Cumberlidge

2014-11-01

Full Text Available The freshwater crabs of the Neotropics comprise 311 species in two families (Pseudothelphusidae and Trichodactylidae and one or both of these families are found in all of the countries in the Neotropical region (except for Chile and some of the Caribbean islands. Colombia (102 species, 81% endemic and Mexico (67 species, 95% endemic are the biodiversity hotspots of freshwater crab species richness and country-level endemism for this region. The results of the IUCN Red List conservation assessments show that 34% of pseudothelphusids and 10% of trichodactylids have an elevated risk of extinction, 29% of pseudothelphusids and 75% of trichodactylids are not at-risk (Least Concern, and although none are actually extinct, 56% of pseudothelphusids and 17% of trichodactylids are too poorly known to assess (Data Deficient. Colombia (14 species, Venezuela (7 species, Mexico (6 species, and Ecuador (5 species are the countries with the highest number of threatened species of Neotropical freshwater crabs. The majority of threatened species are restricted-range semiterrestrial endemics living in habitats subjected to deforestation, alteration of drainage patterns, and pollution. This underlines the need to prioritize and develop conservation measures before species decline to levels from which they cannot recover. These results represent a baseline that can be used to design strategies to save threatened Neotropical species of freshwater crabs.

Adventive Vertebrates and Historical Ecology in the Pre-Columbian Neotropics

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Peter W. Stahl

2009-12-01

Full Text Available The arrival of Europeans in the Western Hemisphere (ca. AD 1500 is generally used as a convenient reference point for signaling the early appearance of invasive faunas. Although use of this date embraces an implicit belief in benign landscape management by pre-Columbian inhabitants of the Americas, substantial evidence for the anthropogenic movement of domesticated, wild, and synanthropic vertebrates throughout the Neotropics suggests that it may be an exaggerated and erroneous reference point for the aims of ecological restoration and biological conservation.

Sexual Success after Stress? Imidacloprid-Induced Hormesis in Males of the Neotropical Stink Bug Euschistus heros

Science.gov (United States)

Haddi, Khalid; Mendes, Marcos V.; Lino-Neto, José; Freitas, Hemerson L.; Guedes, Raul Narciso C.; Oliveira, Eugênio E.

2016-01-01

Environmental stress in newly-emerged adult insects can have dramatic consequences on their life traits (e.g., dispersion, survival and reproduction) as adults. For instance, insects sublethally exposed to environmental stressors (e.g., insecticides) can gain fitness benefits as a result of hormesis (i.e., benefits of low doses of compounds that would be toxic at higher doses). Here, we experimentally tested whether sublethal exposure to the insecticide imidacloprid would hormetically affect the sexual fitness of newly-emerged adults of the Neotropical brown stink bug Euschistus heros (Hemiptera: Heteroptera: Pentatomidae), which is the most abundant and prevalent insect pest in Neotropical soybean fields. We evaluated the sexual fitness of four couple combinations: unexposed couples, exposed females, exposed males, and exposed couples. Sublethal exposure to dry residues (i.e., contact) of imidacloprid (at 1% of recommended field rate) did not affect insect survival, but led to higher mating frequencies when at least one member of the couple was exposed. However, the average mating duration was shortened when only females were exposed to imidacloprid. Moreover, exposed males showed higher locomotory (walking) activity, lower respiration rates and induced higher fecundity rates when mated to unexposed females. Although the reproductive tracts of exposed males did not differ morphometrically from unexposed males, their accessory glands exhibited positive reactions for acidic and basic contents. Our findings suggest that males of the Neotropical brown stink bug hormetically increase their sexual fitness when cued by impending insecticidal stress in early adulthood. PMID:27284906

Sexual Success after Stress? Imidacloprid-Induced Hormesis in Males of the Neotropical Stink Bug Euschistus heros.

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Khalid Haddi

Full Text Available Environmental stress in newly-emerged adult insects can have dramatic consequences on their life traits (e.g., dispersion, survival and reproduction as adults. For instance, insects sublethally exposed to environmental stressors (e.g., insecticides can gain fitness benefits as a result of hormesis (i.e., benefits of low doses of compounds that would be toxic at higher doses. Here, we experimentally tested whether sublethal exposure to the insecticide imidacloprid would hormetically affect the sexual fitness of newly-emerged adults of the Neotropical brown stink bug Euschistus heros (Hemiptera: Heteroptera: Pentatomidae, which is the most abundant and prevalent insect pest in Neotropical soybean fields. We evaluated the sexual fitness of four couple combinations: unexposed couples, exposed females, exposed males, and exposed couples. Sublethal exposure to dry residues (i.e., contact of imidacloprid (at 1% of recommended field rate did not affect insect survival, but led to higher mating frequencies when at least one member of the couple was exposed. However, the average mating duration was shortened when only females were exposed to imidacloprid. Moreover, exposed males showed higher locomotory (walking activity, lower respiration rates and induced higher fecundity rates when mated to unexposed females. Although the reproductive tracts of exposed males did not differ morphometrically from unexposed males, their accessory glands exhibited positive reactions for acidic and basic contents. Our findings suggest that males of the Neotropical brown stink bug hormetically increase their sexual fitness when cued by impending insecticidal stress in early adulthood.

Study of tungsten surface interaction with plasma streams at DPF-1000U

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Ladygina Marina S.

2015-06-01

Full Text Available In this note experimental studies of tungsten (W samples irradiated by intense plasma-ion streams are reported. Measurements were performed using the modified plasma focus device DPF-1000U equipped with an axial gas-puffing system. The main diagnostic tool was a Mechelle®900 optical spectrometer. The electron density of a freely propagating plasma stream (i.e., the plasma stream observed without any target inside the vacuum chamber was estimated on the basis of the half-width of the Dβ spectral line, taking into account the linear Stark effect. For a freely propagating plasma stream the maximum electron density amounted to about 1.3 × 1017 cm−3 and was reached during the maximum plasma compression. The plasma electron density depends on the initial conditions of the experiments. It was thus important to determine first the plasma flow characteristics before attempting any target irradiation. These data were needed for comparison with plasma characteristics after an irradiation of the investigated target. In fact, spectroscopic measurements performed during interactions of plasma streams with the investigated W samples showed many WI and WII spectral lines. The surface erosion was determined from mass losses of the irradiated samples. Changes on the surfaces of the irradiated samples were also investigated with an optical microscope and some sputtering and melting zones were observed.

Neotropical peatland methane emissions along a vegetation and biogeochemical gradient.

Science.gov (United States)

Winton, R Scott; Flanagan, Neal; Richardson, Curtis J

2017-01-01

Tropical wetlands are thought to be the most important source of interannual variability in atmospheric methane (CH4) concentrations, yet sparse data prevents them from being incorporated into Earth system models. This problem is particularly pronounced in the neotropics where bottom-up models based on water table depth are incongruent with top-down inversion models suggesting unaccounted sinks or sources of CH4. The newly documented vast areas of peatlands in the Amazon basin may account for an important unrecognized CH4 source, but the hydrologic and biogeochemical controls of CH4 dynamics from these systems remain poorly understood. We studied three zones of a peatland in Madre de Dios, Peru, to test whether CH4 emissions and pore water concentrations varied with vegetation community, soil chemistry and proximity to groundwater sources. We found that the open-canopy herbaceous zone emitted roughly one-third as much CH4 as the Mauritia flexuosa palm-dominated areas (4.7 ± 0.9 and 14.0 ± 2.4 mg CH4 m-2 h-1, respectively). Emissions decreased with distance from groundwater discharge across the three sampling sites, and tracked changes in soil carbon chemistry, especially increased soil phenolics. Based on all available data, we calculate that neotropical peatlands contribute emissions of 43 ± 11.9 Tg CH4 y-1, however this estimate is subject to geographic bias and will need revision once additional studies are published.

Neotropical peatland methane emissions along a vegetation and biogeochemical gradient.

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R Scott Winton

Full Text Available Tropical wetlands are thought to be the most important source of interannual variability in atmospheric methane (CH4 concentrations, yet sparse data prevents them from being incorporated into Earth system models. This problem is particularly pronounced in the neotropics where bottom-up models based on water table depth are incongruent with top-down inversion models suggesting unaccounted sinks or sources of CH4. The newly documented vast areas of peatlands in the Amazon basin may account for an important unrecognized CH4 source, but the hydrologic and biogeochemical controls of CH4 dynamics from these systems remain poorly understood. We studied three zones of a peatland in Madre de Dios, Peru, to test whether CH4 emissions and pore water concentrations varied with vegetation community, soil chemistry and proximity to groundwater sources. We found that the open-canopy herbaceous zone emitted roughly one-third as much CH4 as the Mauritia flexuosa palm-dominated areas (4.7 ± 0.9 and 14.0 ± 2.4 mg CH4 m-2 h-1, respectively. Emissions decreased with distance from groundwater discharge across the three sampling sites, and tracked changes in soil carbon chemistry, especially increased soil phenolics. Based on all available data, we calculate that neotropical peatlands contribute emissions of 43 ± 11.9 Tg CH4 y-1, however this estimate is subject to geographic bias and will need revision once additional studies are published.

Phytogeography and conservation of neotropical dry forest with emphasis on Columbia

OpenAIRE

Banda Rodriguez, Karina Paola

2017-01-01

Dry forest is one of the most threatened tropical forests in the world. Human impact has caused its massive transformation but conservation of dry forest has often been neglected across Latin America. In Colombia, less than 10% of the original extension of dry forest remains. This thesis studies the phytogeography of neotropical dry forest and its relevance for conservation using data from 1602 tree species inventories made in dry forests across Latin America and the Caribbean ...

Continental cichlid radiations: functional diversity reveals the role of changing ecological opportunity in the Neotropics.

Science.gov (United States)

Arbour, Jessica Hilary; López-Fernández, Hernán

2016-08-17

Adaptive radiations have been hypothesized to contribute broadly to the diversity of organisms. Models of adaptive radiation predict that ecological opportunity and ecological release, the availability of empty ecological niches and the response by adapting lineages to occupy them, respectively, drive patterns of phenotypic and lineage diversification. Adaptive radiations driven by 'ecological opportunity' are well established in island systems; it is less clear if ecological opportunity influences continent-wide diversification. We use Neotropical cichlid fishes to test if variation in rates of functional evolution is consistent with changing ecological opportunity. Across a functional morphological axis associated with ram-suction feeding traits, evolutionary rates declined through time as lineages diversified in South America. Evolutionary rates of ram-suction functional morphology also appear to have accelerated as cichlids colonized Central America and encountered renewed opportunity. Our results suggest that ecological opportunity may play an important role in shaping patterns of morphological diversity of even broadly distributed lineages like Neotropical cichlids. © 2016 The Author(s).

Bats (Chiroptera: Noctilionoidea) Challenge a Recent Origin of Extant Neotropical Diversity.

Science.gov (United States)

Rojas, Danny; Warsi, Omar M; Dávalos, Liliana M

2016-05-01

The mechanisms underlying the high extant biodiversity in the Neotropics have been controversial since the 19th century. Support for the influence of period-specific changes on diversification often rests on detecting more speciation events during a particular period. The timing of speciation events may reflect the influence of incomplete taxon sampling, protracted speciation, and null processes of lineage accumulation. Here we assess the influence of these factors on the timing of speciation with new multilocus data for New World noctilionoid bats (Chiroptera: Noctilionoidea). Biogeographic analyses revealed the importance of the Neotropics in noctilionoid diversification, and the critical role of dispersal. We detected no shift in speciation rate associated with the Quaternary or pre-Quaternary periods, and instead found an increase in speciation linked to the evolution of the subfamily Stenodermatinae (∼18 Ma). Simulations modeling constant speciation and extinction rates for the phylogeny systematically showed more speciation events in the Quaternary. Since recording more divergence events in the Quaternary can result from lineage accumulation, the age of extant sister species cannot be interpreted as supporting higher speciation rates during this period. Instead, analyzing the factors that influence speciation requires modeling lineage-specific traits and environmental, spatial, and ecological drivers of speciation. © The Author(s) 2016. Published by Oxford University Press, on behalf of the Society of Systematic Biologists. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Predominance of self-compatibility in hummingbird-pollinated plants in the Neotropics

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Wolowski, Marina; Saad, Carolina Farias; Ashman, Tia-Lynn; Freitas, Leandro

2013-01-01

Both plant traits and plant-pollinator interactions are thought to influence plant mating systems. For hummingbird-pollinated plants, foraging strategy (territorial or traplining) is also expected to influence plant mating. We hypothesize that the traplining behavior of hermits promotes outcrossing, whereas the behavior of non-hermits favours self-incompatibility. Thus, selection is expected to maintain self-incompatibility in plants pollinated by non-hermits. We explore the incidence of self-incompatibility in Neotropical hummingbird-pollinated plants and its association with hummingbird behavior and plant traits. We conducted a literature review (56 species) and performed hand-pollination experiments in 27 hummingbird-pollinated plants in an Atlantic rainforest. We found that self-incompatibility (measured as hummingbird-pollinated plants. The interaction of hummingbird and habit type affected ISI, as did phylogenetic relationships. Specifically, herbs pollinated by non-hermits had higher ISI than woody plants pollinated by non-hermits, and herbs pollinated by both hermits and non-hermits. For the Atlantic rainforest plant guild, 30 % of the species were self-incompatible. ISI was higher in herbs than in woody species and increased with plant aggregation but was not dependent on foraging behavior, plant density, or floral display. Although hummingbirds differ in their foraging strategies, these behavioral differences seem to have only a minor influence on the incidence of self-incompatibility. Phylogenetic relatedness seems to be the strongest determinant of mating system in Neotropical hummingbird-pollinated plants.

The importance of a Biosphere Reserve of Atlantic Forest for the conservation of stream fauna

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CE. Yoshida

Full Text Available Preservation of terrestrial fauna and flora has been the main reason for the settlement of most protected areas in the past 30 years, but although those areas may include water bodies, this does not necessarily mean that the biodiversity of freshwater environments are also protected. In the present study, the fauna inventory of eight streams (1st, 2nd, 4th and 5th orders of three microbasins of Japi Mountain, a Biosphere Reserve of Atlantic Forest recognised by UNESCO since 1994, located in São Paulo state, southeast of Brazil, was conducted. The hypothesis of this study is that the conservation of this area is important for the maintenance of the aquatic biodiversity of this biome, and so, this world hotspot deserves priority conservation actions. From 2005 to 2007, benthic macroinvertebrates, fishes and, eventually, anuran amphibians were sampled in these streams. The results showed that Japi Mountain contributes to the conservation of 138 taxonomic units of the aquatic biota and covers a rich and representative biodiversity of freshwater fauna of the world (0.2%, Neotropical region (0.9%, Brazil (2.4% and São Paulo state (17.9%. The studied streams in the Environmental Protection Area help protect endangered taxa like the fishes Neoplecostomus paranensis and Pareiorhina cf rudolphi, and shelter freshwater invertebrates and fishes whose distribution is restricted to the Brazilian territory. Japi Mountain is also an important haven of species that was missing there like the frog species Vitreorana eurygnatha. Thus, this species inventory emphasises the importance of conservation actions of the freshwater environments of this Biosphere Reserve of Atlantic Forest.

The importance of a Biosphere Reserve of Atlantic Forest for the conservation of stream fauna.

Science.gov (United States)

Yoshida, C E; Uieda, V S

2014-05-01

Preservation of terrestrial fauna and flora has been the main reason for the settlement of most protected areas in the past 30 years, but although those areas may include water bodies, this does not necessarily mean that the biodiversity of freshwater environments are also protected. In the present study, the fauna inventory of eight streams (1st, 2nd, 4th and 5th orders) of three microbasins of Japi Mountain, a Biosphere Reserve of Atlantic Forest recognised by UNESCO since 1994, located in São Paulo state, southeast of Brazil, was conducted. The hypothesis of this study is that the conservation of this area is important for the maintenance of the aquatic biodiversity of this biome, and so, this world hotspot deserves priority conservation actions. From 2005 to 2007, benthic macroinvertebrates, fishes and, eventually, anuran amphibians were sampled in these streams. The results showed that Japi Mountain contributes to the conservation of 138 taxonomic units of the aquatic biota and covers a rich and representative biodiversity of freshwater fauna of the world (0.2%), Neotropical region (0.9%), Brazil (2.4%) and São Paulo state (17.9%). The studied streams in the Environmental Protection Area help protect endangered taxa like the fishes Neoplecostomus paranensis and Pareiorhina cf rudolphi, and shelter freshwater invertebrates and fishes whose distribution is restricted to the Brazilian territory. Japi Mountain is also an important haven of species that was missing there like the frog species Vitreorana eurygnatha. Thus, this species inventory emphasises the importance of conservation actions of the freshwater environments of this Biosphere Reserve of Atlantic Forest.

Do birds select habitat or food resources? Nearctic-neotropic migrants in northeastern Costa Rica

Science.gov (United States)

Jared D. Wolfe; Matthew D. Johnson; C. John Ralph; R. Mark Brigham

2014-01-01

Nearctic-neotropic migrant birds need to replenish energy reserves during stopover periods to successfully complete their semiannual movements. In this study we used linear models to examine the habitat use of 11 migrant species in northeastern Costa Rica to better understand the influence of food and structural resources on the presence of birds during stopover...

Araucnephia iberaensis n. sp., a Neotropical Black Fly with a Peculiar Distribution (Diptera-Simuliidae

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S Coscarón

2002-01-01

Full Text Available Araucnephia Wygodzinsky & Coscarón is a Neotropical black fly genus in which only one species from Central Chile is known. Another species has now been found in Corrientes province on the eastern side of the Iberá tropical swamps of Argentina, on the western border of the mountainous region of southern Brazil. This new species, A. iberaensis, is herein described and illustrated and information on its bionomics is recorded. It is an interesting species because previous to its discovery no black fly genus or subgenus from Central Chile region has been found in tropical areas, because these two regions are separated by the Monte and Pampas realms. Similarly, no Brazilian genus or subgenus has crossed the Andes mountains to Chile. A comparison with other Neotropical, Nearctic, Ethiopian (Afrotropical and Australian Prosimuliini (sensu Crosskey & Howard showed Araucnephia to be a valid taxon most closely related to Araucnephioides (sympatric in Chile. Araucnephia also shows great affinities with Lutzsimulium from Southeast Brazil and Argentina and Paracnephia from South Africa.

A new genus and species of Neotropical Nemobiinae (Insecta: Orthoptera: Grylloidea: Trigonidiidae: Nemobiinae).

Science.gov (United States)

Jesus, Fabiene Maria DE; Pereira, Marcelo Ribeiro; Rodrigues, Geanne Carla Ripani; Sperber, Carlos Frankl

2017-06-09

A new genus and a new species of Neotropical cricket is described: Pepoapua cariacica n. gen., n. sp., occurring in four Atlantic Forest remnants in the states of Bahia and Espírito Santo, Brazil. This new genus is morphologically similar in external characteristics, both male and female genitalia, with two other Neotropical genera of Nemobiinae: Amanayara and Kevanemobius. The combination of the external morphological characteristics, along with male genitalia, characterize a new genus through combination of the following characters: (i) males and females with morphologically similar tegmina; (ii) tegmina reduced, not reaching half of the second abdominal segment; (iii) dorsal field of the tegmina with parallel veins, without stridulatory vein or any specialized area for sound production; (iv) tibia of the first pair of legs without tympanum; (v) tibia of the third pair of legs with seven dorsal spurs, four inner and three outer, the proximo-dorsal inner spur reduced in size and the disto-dorsal inner spur without glandular aspect; (vi) ovipositor with distal portion of the dorsal and ventral valves serrated; (vii) male genitalia without evident bristles or sensillas; (viii) pseudepiphallic median lobe presenting apical and ventral projections.

Integrative taxonomy detects cryptic and overlooked fish species in a neotropical river basin.

Science.gov (United States)

Gomes, Laís Carvalho; Pessali, Tiago Casarim; Sales, Naiara Guimarães; Pompeu, Paulo Santos; Carvalho, Daniel Cardoso

2015-10-01

The great freshwater fish diversity found in the neotropical region makes management and conservation actions challenging. Due to shortage of taxonomists and insufficient infrastructure to deal with such great biodiversity (i.e. taxonomic impediment), proposed remedies to accelerate species identification and descriptions include techniques that combine DNA-based identification and concise morphological description. The building of a DNA barcode reference database correlating meristic and genetic data was developed for 75 % of the Mucuri River basin's freshwater fish. We obtained a total of 141 DNA barcode sequences from 37 species belonging to 30 genera, 19 families, and 5 orders. Genetic distances within species, genera, and families were 0.74, 9.5, and 18.86 %, respectively. All species could be clearly identified by the DNA barcodes. Divergences between meristic morphological characteristics and DNA barcodes revealed two cryptic species among the Cyphocharax gilbert and Astyanax gr. bimaculatus specimens, and helped to identify two overlooked species within the Gymnotus and Astyanax taxa. Therefore, using a simplified model of neotropical biodiversity, we tested the efficiency of an integrative taxonomy approach for species discovery, identification of cryptic diversity, and accelerating biodiversity descriptions.

An illustrated key to Neotropical species of the genus Meteorus Haliday ( Hymenoptera , Braconidae , Euphorinae )

OpenAIRE

Aguirre, Helmuth; de Almeida, Luis Felipe; Shaw, Scott Richard; Sarmiento, Carlos E.

2015-01-01

Abstract A comprehensive key for 75 species of Meteorus distributed across 15 Neotropical countries is presented. Eleven new species from Bolivia, Costa Rica and Ecuador are described: Meteorus albistigma , Meteorus carolae , Meteorus eurysaccavorus , Meteorus fallacavus , Meteorus flavistigma , Meteorus haimowitzi , Meteorus magnoculus , Meteorus martinezi , Meteorus microcavus , Meteorus noctuivorus and Meteorus orion . Expanded range distributions are recorded for Meteorus andreae , Meteor...

First Record of Scirtidae (Coleoptera Associated With Decaying Carcasses in the Neotropical Region

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Rodrigo Farias

2013-07-01

Resumo. Durante um estudo de dois anos da entomofauna associada a carcaças de suínos em um remanescente de Mata Atlântica em João Pessoa, PB, Brasil, foram coletados 127 indivíduos de Scirtes sp. Este é o primeiro registro de exemplares da família Scirtidae associados a carcaças na região Neotropical.

New species and records of Zavreliella Kieffer, 1920 from Neotropical region (Diptera: Chironomidae).

Science.gov (United States)

Fusari, Lívia Maria; Pinho, Luiz Carlos; Lamas, Carlos José Einicker

2017-01-19

A new species of Zavreliella Kieffer, Zavreliella kambeba sp. n., is described, based on male adults collected in the Amazon rainforest, Brazil. Further seven Zavreliella species are recorded for new localities in Brazil, with the first Neotropical record of Z. marmorata (van der Wulp). The genus Zavreliella is now composed of 15 species, of which adult males are reviewed in a key to their identification.

Diversification in the northern neotropics: mitochondrial and nuclear DNA phylogeography of the iguana Ctenosaura pectinata and related species.

Science.gov (United States)

Zarza, Eugenia; Reynoso, Victor H; Emerson, Brent C

2008-07-01

While Quaternary climatic changes are considered by some to have been a major factor promoting speciation within the neotropics, others suggest that much of the neotropical species diversity originated before the Pleistocene. Using mitochondrial and nuclear sequence data, we evaluate the relative importance of Pleistocene and pre-Pleistocene events within the evolutionary history of the Mexican iguana Ctenosaura pectinata, and related species. Results support the existence of cryptic lineages with strong mitochondrial divergence (> 4%) among them. Some of these lineages form zones of secondary contact, with one of them hybridizing with C. hemilopha. Evolutionary network analyses reveal the oldest populations of C. pectinata to be those of the northern and southern Mexican coastal regions. Inland and mid-latitudinal coastal populations are younger in age as a consequence of a history of local extinction within these regions followed by re-colonization. Estimated divergence times suggest that C. pectinata originated during the Pliocene, whereas geographically distinct mitochondrial DNA lineages first started to diverge during the Pliocene, with subsequent divergence continuing through the Pleistocene. Our results highlight the influence of both Pliocene and Pleistocene events in shaping the geographical distribution of genetic variation within neotropical lowland organisms. Areas of high genetic diversity in southern Mexico were detected, this finding plus the high levels of genetic diversity within C. pectinata, have implications for the conservation of this threatened species.

The specimens of Parulidae from the Neotropics in the collection of the Zoological Museum Amsterdam

NARCIS (Netherlands)

Prins, Tineke G.

1992-01-01

The Parulidae form a group of little dainty birds with slender bills consisting of 126 species. The family is confined to the New World, the largest number of species and genera being found in North and Central America. Neotropical material of 35 species is represented in the collection of the

Differential Responses of Neotropical Mountain Forests to Climate Change during the Last Millenium

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Figueroa-Rangel, B. L.; Olvera Vargas, M.

2013-05-01

The long-term perspective in the conservation of mountain ecosystems using palaeoecological and paleoclimatological techniques are providing with crucial information for the understanding of the temporal range and variability of ecological pattern and processes. This perception is contributing with means to anticipate future conditions of these ecosystems, especially their response to climate change. Neotropical mountain forests, created by a particular geological and climatic history in the Americas, represent one of the most distinctive ecosystems in the tropics which are constantly subject to disturbances included climate change. Mexico due to its geographical location between the convergence of temperate and tropical elements, its diverse physiography and climatic heterogeneity, contains neotropical ecosystems with high biodiversity and endemicity whose structure and taxonomical composition have changed along centurial to millennial scales. Different neotropical forests expand along the mountain chains of Mexico with particular responses along spatial and temporal scales. Therefore in order to capture these scales at fine resolution, sedimentary sequences from forest hollows were retrieved from three forest at different altitudes within 10 km; Pine forest (PF), Transitional forest (TF) and Cloud forest (CF). Ordination techniques were used to relate changes in vegetation with the environment every ~60 years. The three forests experience the effect of the dry stage ~AD 800-1200 related to the Medieval Warm Period reported for several regions of the world. CF contracted, PF expanded while the TF evolved from CF to a community dominated by dry-resistant epiphytes. Dry periods in PF and TF overlapped with the increase in fire occurrences while a dissimilar pattern took place in CF. Maize, Asteraceae and Poaceae were higher during dry intervals while epiphytes decreased. A humid period ~1200-1450 AD was associated with an expansion and a high taxa turnover in CF

Polyphyly of the hawk genera Leucopternis and Buteogallus (Aves, Accipitridae): multiple habitat shifts during the Neotropical buteonine diversification.

Science.gov (United States)

Amaral, Fabio S Raposo do; Miller, Matthew J; Silveira, Luís Fábio; Bermingham, Eldredge; Wajntal, Anita

2006-02-07

The family Accipitridae (hawks, eagles and Old World vultures) represents a large radiation of predatory birds with an almost global distribution, although most species of this family occur in the Neotropics. Despite great morphological and ecological diversity, the evolutionary relationships in the family have been poorly explored at all taxonomic levels. Using sequences from four mitochondrial genes (12S, ATP8, ATP6, and ND6), we reconstructed the phylogeny of the Neotropical forest hawk genus Leucopternis and most of the allied genera of Neotropical buteonines. Our goals were to infer the evolutionary relationships among species of Leucopternis, estimate their relationships to other buteonine genera, evaluate the phylogenetic significance of the white and black plumage patterns common to most Leucopternis species, and assess general patterns of diversification of the group with respect to species' affiliations with Neotropical regions and habitats. Our molecular phylogeny for the genus Leucopternis and its allies disagrees sharply with traditional taxonomic arrangements for the group, and we present new hypotheses of relationships for a number of species. The mtDNA phylogenetic trees derived from analysis of the combined data posit a polyphyletic relationship among species of Leucopternis, Buteogallus and Buteo. Three highly supported clades containing Leucopternis species were recovered in our phylogenetic reconstructions. The first clade consisted of the sister pairs L. lacernulatus and Buteogallus meridionalis, and Buteogallus urubitinga and Harpyhaliaetus coronatus, in addition to L. schistaceus and L. plumbeus. The second clade included the sister pair Leucopternis albicollis and L. occidentalis as well as L. polionotus. The third lineage comprised the sister pair L. melanops and L. kuhli, in addition to L. semiplumbeus and Buteo buteo. According to our results, the white and black plumage patterns have evolved at least twice in the group. Furthermore

Polyphyly of the hawk genera Leucopternis and Buteogallus (Aves, Accipitridae: multiple habitat shifts during the Neotropical buteonine diversification

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Bermingham Eldredge

2006-02-01

Full Text Available Abstract Background The family Accipitridae (hawks, eagles and Old World vultures represents a large radiation of predatory birds with an almost global distribution, although most species of this family occur in the Neotropics. Despite great morphological and ecological diversity, the evolutionary relationships in the family have been poorly explored at all taxonomic levels. Using sequences from four mitochondrial genes (12S, ATP8, ATP6, and ND6, we reconstructed the phylogeny of the Neotropical forest hawk genus Leucopternis and most of the allied genera of Neotropical buteonines. Our goals were to infer the evolutionary relationships among species of Leucopternis, estimate their relationships to other buteonine genera, evaluate the phylogenetic significance of the white and black plumage patterns common to most Leucopternis species, and assess general patterns of diversification of the group with respect to species' affiliations with Neotropical regions and habitats. Results Our molecular phylogeny for the genus Leucopternis and its allies disagrees sharply with traditional taxonomic arrangements for the group, and we present new hypotheses of relationships for a number of species. The mtDNA phylogenetic trees derived from analysis of the combined data posit a polyphyletic relationship among species of Leucopternis, Buteogallus and Buteo. Three highly supported clades containing Leucopternis species were recovered in our phylogenetic reconstructions. The first clade consisted of the sister pairs L. lacernulatus and Buteogallus meridionalis, and Buteogallus urubitinga and Harpyhaliaetus coronatus, in addition to L. schistaceus and L. plumbeus. The second clade included the sister pair Leucopternis albicollis and L. occidentalis as well as L. polionotus. The third lineage comprised the sister pair L. melanops and L. kuhli, in addition to L. semiplumbeus and Buteo buteo. According to our results, the white and black plumage patterns have evolved

Phylogenetic signal and major ecological shifts in the ecomorphological structure of stream fish in two river basins in Brazil

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Camilo Andrés Roa-Fuentes

Full Text Available We tested the contribution of the phylogenetic and specific components to the ecomorphological structure of stream fish from the upper Paraguai River and upper São Francisco River basins, and identified nodes in the phylogenetic tree at which major ecological shifts occurred. Fish were sampled between June and October of 2008 in 12 streams (six in each basin. In total, 22 species from the upper Paraguai River basin and 12 from the upper São Francisco River were analyzed. The ecomorphological patterns exhibited phylogenetic signal, indicating that the ecomorphological similarity among species is associated with the degree of relatedness. A strong habitat template is most likely to be the primary cause for a high phylogenetic signal. A significant contribution from the specific component was also detected, supporting the idea that the phylogenetic signal occurs in some clades for some traits, but not in others. The major ecological shifts were observed in the basal nodes, suggesting that ecological niche differences appear to accumulate early in the evolutionary history of major clades. This finding reinforces the role of key traits in the diversification of Neotropical fishes. Ecological shifts in recent groups could be related to morphological modifications associated with habitat use.

MoSI (Monitoreo de Sobrevivencia Invernal): assessing habitat-specific overwintering survival of neotropical migratory landbirds

Science.gov (United States)

David F. DeSante; T. Scott Sillett; Rodney B. Siegel; James F. Saracco; Claudia A. Romo de Vivar Alvarez; Salvadora Morales; Alexis Cerezo; Danielle R. Kaschube; Manuel Grosselet; Borja Mila

2005-01-01

Recent evidence suggests that population declines in many Neotropical-wintering migratory landbird species are caused by habitat loss and degradation on their wintering grounds. Such habitat loss and degradation can lower overwintering survival rates and cause surviving birds to leave their wintering grounds in poor physical condition, leading to high mortality during...

Leucophora Satellite Flies (Diptera: Anthomyiidae) as Nest Parasites of Sweat Bees (Hymenoptera: Halictidae) in the Neotropics.

Science.gov (United States)

Polidori, C; Michelsen, V; Nieves-Aldrey, J L

2015-08-01

The biology of the 10 species of Leucophora (Diptera: Anthomyiidae) recorded in the Neotropics remains unknown. The large majority of the studied species so far are kleptoparasites of bees and wasps. Here, we report the first observations of Leucophora andicola (Bigot) and Leucophora peullae (Malloch) visiting the nests of ground-nesting sweat bees Corynura (Hymenoptera: Halictidae) in Chilean Patagonia. Females of both species perch on small stones or sticks within a dense nest aggregation of the bees and then track pollen-loaded bees in flight with great precision, eventually following them into their nests. The overall behavior closely resembles that observed for many other species of the genus. Excavations of some bee nests returned only two dipteran puparia, possibly of Leucophora, suggesting a low parasitism rate. One male of L. peullae was also collected at the bee aggregation. This is the first report of host association for any Leucophora from the Neotropics and the first report of any anthomyiid fly associated with augochlorine bees.

Streaming instabilities in a collisional dusty plasma

International Nuclear Information System (INIS)

Mamun, A. A.; Shukla, P. K.

2000-01-01

A pair of low-frequency electrostatic modes, which are very similar to those experimentally observed by Praburam and Goree [Phys. Plasmas 3, 1212 (1996)], are found to exist in a dusty plasma with a significant background neutral pressure and background ion streaming. One of these two modes is the dust-acoustic mode and the other one is a new mode which is due to the combined effects of the ion streaming and ion--neutral collisions. It has been shown that in the absence of the ion streaming, the dust-acoustic mode is damped due to the combined effects of the ion--neutral and dust--neutral collisions and the electron--ion recombination onto the dust grain surface. This result disagrees with Kaw and Singh [Phys. Rev. Lett. 79, 423 (1997)], who reported collisional instability of the dust-acoustic mode in such a dusty plasma. It has also been found that a streaming instability with the growth rate of the order of the dust plasma frequency is triggered when the background ion streaming speed relative to the charged dust particles is comparable or higher than the ion--thermal speed. This point completely agrees with Rosenberg [J. Vac. Soc. Technol. A 14, 631 (1996)

Photonic Free-Electron Lasers

NARCIS (Netherlands)

van der Slot, Petrus J.M.; Denis, T.; Lee, J.H.H.; van Dijk, M.W.; Boller, Klaus J.

2012-01-01

A photonic free-electron laser (pFEL) produces coherent Cerenkov radiation from a set of parallel electron beams streaming through a photonic crystal. The function of the crystal is to slow down the phase velocity of a copropagating electromagnetic wave, such that also mildly relativistic electrons

A revision of the Neotropical genus Paraberismyia Woodley (Diptera, Stratiomyidae, Beridinae with three new species

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Norman Woodley

2013-11-01

Full Text Available The Neotropical genus Paraberismyia Woodley, 1995, is revised. Three new species, P. chiapas sp. n., P.mathisi sp. n., and P. triunfo sp. n. are described, alltype localities in Chiapas, Mexico. A key to the four known species is provided.

Atractiellomycetes belonging to the ‘rust’ lineage (Pucciniomycotina) form mycorrhizae with terrestrial and epiphytic neotropical orchids

Science.gov (United States)

Kottke, Ingrid; Suárez, Juan Pablo; Herrera, Paulo; Cruz, Dario; Bauer, Robert; Haug, Ingeborg; Garnica, Sigisfredo

2010-01-01

Distinctive groups of fungi are involved in the diverse mycorrhizal associations of land plants. All previously known mycorrhiza-forming Basidiomycota associated with trees, ericads, liverworts or orchids are hosted in Agaricomycetes, Agaricomycotina. Here we demonstrate for the first time that Atractiellomycetes, members of the ‘rust’ lineage (Pucciniomycotina), are mycobionts of orchids. The mycobionts of 103 terrestrial and epiphytic orchid individuals, sampled in the tropical mountain rainforest of Southern Ecuador, were identified by sequencing the whole ITS1-5.8S-ITS2 region and part of 28S rDNA. Mycorrhizae of 13 orchid individuals were investigated by transmission electron microscopy. Simple septal pores and symplechosomes in the hyphal coils of mycorrhizae from four orchid individuals indicated members of Atractiellomycetes. Molecular phylogeny of sequences from mycobionts of 32 orchid individuals out of 103 samples confirmed Atractiellomycetes and the placement in Pucciniomycotina, previously known to comprise only parasitic and saprophytic fungi. Thus, our finding reveals these fungi, frequently associated to neotropical orchids, as the most basal living basidiomycetes involved in mycorrhizal associations of land plants. PMID:20007181

Electrical field excitation in non-uniform plasma by a modulated electron beam

International Nuclear Information System (INIS)

Anisimov, I.O.; Borisov, O.A.

2000-01-01

Excitation of electric fields due to a modulated electron beam in a warm non-uniform plasma is treated for weak beams in warm plasma. It is shown that the maximum electric field magnitude that is reached near the local plasma resonance point depends significantly on the direction of the electron stream motion. In collisional plasma the magnitude of the Langmuir wave that propagates to the subcritical plasma also depends on the direction of the electron stream motion. The motion of the modulated electron stream front results in beatings between oscillations on the modulation frequency and on the local electron plasma frequencies at the initial moment. Later these beatings damp in the supercritical plasma, whereas in the subcritical plasma they are transformed into spatial beatings between the field of the modulated electron stream and the excited Langmuir wave. (orig.)

Genetic and metabolic biodiversity of Trichoderma from Colombia and adjacent neotropic regions.

Science.gov (United States)

Hoyos-Carvajal, Lilliana; Orduz, Sergio; Bissett, John

2009-09-01

The genus Trichoderma has been studied for production of enzymes and other metabolites, as well as for exploitation as effective biological control agents. The biodiversity of Trichoderma has seen relatively limited study over much of the neotropical region. In the current study we assess the biodiversity of 183 isolates from Mexico, Guatemala, Panama, Ecuador, Peru, Brazil and Colombia, using morphological, metabolic and genetic approaches. A comparatively high diversity of species was found, comprising 29 taxa: Trichoderma asperellum (60 isolates), Trichoderma atroviride (3), Trichoderma brevicompactum (5), Trichoderma crassum (3), Trichoderma erinaceum (3), Trichoderma gamsii (2), Trichoderma hamatum (2), Trichoderma harzianum (49), Trichoderma koningiopsis (6), Trichoderma longibrachiatum (3), Trichoderma ovalisporum (1), Trichoderma pubescens (2), Trichoderma rossicum (4), Trichoderma spirale (1), Trichoderma tomentosum (3), Trichoderma virens (8), Trichoderma viridescens (7) and Hypocrea jecorina (3) (anamorph: Trichoderma reesei), along with 11 currently undescribed species. T. asperellum was the prevalent species and was represented by two distinct genotypes with different metabolic profiles and habitat preferences. The second predominant species, T. harzianum, was represented by three distinct genotypes. The addition of 11 currently undescribed species is evidence of the considerable unresolved biodiversity of Trichoderma in neotropical regions. Sequencing of the internal transcribed spacer regions (ITS) of the ribosomal repeat could not differentiate some species, and taken alone gave several misidentifications in part due to the presence of nonorthologous copies of the ITS in some isolates.

Review of the Neotropical species of the family Pterophoridae, part I: Ochyroticinae, Deuterocopinae, Pterophorinae (Platyptiliini, Exelastini, Oxyptilini) (Lepidoptera)

NARCIS (Netherlands)

Gielis, C.

2006-01-01

The Pterophoridae (Ochyroticinae, Deuterocopinae, Pterophorinae (Tribus: Platyptiliini, Exelastini, Oxyptilini)) species of the Neotropical fauna are reviewed. The species are redescribed. Moths are illustrated in colour for the first time, their genitalia are illustrated in line drawings. The

DNA barcoding of freshwater ichthyoplankton in the Neotropics as a tool for ecological monitoring.

Science.gov (United States)

Frantine-Silva, W; Sofia, S H; Orsi, M L; Almeida, F S

2015-09-01

Quantifying and classifying ichthyoplankton is one of the most effective ways of monitoring the recruitment process in fishes. However, correctly identifying the fish based on morphological characters is extremely difficult, especially in the early stages of development. We examined ichthyoplankton from tributaries and reservoirs along the middle stretch of the Paranapanema River, one of the areas most impacted by hydroelectric projects in the Neotropics. Matching DNA sequences of the COI gene (628-648 bp) allowed us to identify 99.25% of 536 samples of eggs (293) and larvae (243) subjected to BOLD-IDS similarity analysis with a species-level threshold of 1.3%. The results revealed 37 species in 27 genera, 15 families and four orders, some 23.8% of documented fish species in the Paranapanema River. Molecular identification meant that we could include data from egg samples that accounted for about 30% of the species richness observed. The results in this study confirm the efficacy of DNA barcoding in identifying Neotropical ichthyoplankton and show how the data produced provide valuable information for preparing plans for conserving and managing inland waters. © 2015 John Wiley & Sons Ltd.

A key and checklist to the Neotropical forensically important "Little House Flies" (Diptera: Fanniidae

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Diana Grisales

Full Text Available ABSTRACT Fanniidae (Insecta: Diptera is a relatively small family (ca. 350 spp. with five genera, of which Fannia Robineau-Desvoidy, 1830 and Euryomma Stein, 1899 have Neotropical distributions. Some of these species are almost always found in forensic studies. Forensically relevant species have been neglected, despite recent forensic studies that suggest their importance for estimating post-mortem interval (PMI. Thus, current and updated keys to identify adults or larvae on carcasses are unavailable for the most important species. While immature stages are important in estimating PMI, evidence suggests that adults (Fanniidae as well as other families may also be useful for this purpose. Here we provide a key to males of the species of Fanniidae (found on corpses and other decomposing organic matter with a checklist of species that have been used in forensics in the Neotropical region. The key comprises all 38 species of Fannia and Euryomma that have already been successfully used in forensics, and species that are potentially useful for estimating PMI. These records were found after reviews of the literature and data from entomological collections. Photographs and illustrations of the main characters in the key are provided.

Phylogenomics and species delimitation of a complex radiation of Neotropical suboscine birds (Pachyramphus).

Science.gov (United States)

Musher, Lukas J; Cracraft, Joel

2018-01-01

Phylogeographic studies within the Neotropics continue to uncover hidden diversity, the extent of which remains poorly known. In birds, molecular studies are producing evidence that species-level diversity is substantially underestimated. Many avian taxa comprise large complexes of subspecies that often represent species-level taxa by various criteria. One such group of Neotropical suboscine birds, the becards (Pachyramphus), ranges from Argentina through northern Mexico. Their taxonomic limits have been complex and controversial as the genus has bounced around a number of suboscine families. Additionally, the phylogenetic relationships within Pachyramphus are unresolved due to insufficient sampling of taxa and populations across species' ranges. We used target capture of ultraconserved elements for 62 individuals representing 42 taxa, and sequenced two mitochondrial genes and two nuclear introns covering 265 individuals of 51 taxa, including all recognized species, resulting in the most densely and completely sampled phylogenetic hypothesis for Pachyramphus to date. We delimited species using a traditional taxonomic approach and then tested them under a Bayesian multi-species coalescent framework. In doing so, we provide evidence for multiple young, previously undetected evolutionary lineages within Pachyramphus. Deep, well-supported branches and a high number of intraspecific lineages across the tree suggest that at least 50% of species diversity may be unrecognized. Copyright © 2017 Elsevier Inc. All rights reserved.

Diversification of the Genus Anopheles and a Neotropical Clade from the Late Cretaceous.

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Lucas A Freitas

Full Text Available The Anopheles genus is a member of the Culicidae family and consists of approximately 460 recognized species. The genus is composed of 7 subgenera with diverse geographical distributions. Despite its huge medical importance, a consensus has not been reached on the phylogenetic relationships among Anopheles subgenera. We assembled a comprehensive dataset comprising the COI, COII and 5.8S rRNA genes and used maximum likelihood and Bayesian inference to estimate the phylogeny and divergence times of six out of the seven Anopheles subgenera. Our analysis reveals a monophyletic group composed of the three exclusively Neotropical subgenera, Stethomyia, Kerteszia and Nyssorhynchus, which began to diversify in the Late Cretaceous, at approximately 90 Ma. The inferred age of the last common ancestor of the Anopheles genus was ca. 110 Ma. The monophyly of all Anopheles subgenera was supported, although we failed to recover a significant level of statistical support for the monophyly of the Anopheles genus. The ages of the last common ancestors of the Neotropical clade and the Anopheles and Cellia subgenera were inferred to be at the Late Cretaceous (ca. 90 Ma. Our analysis failed to statistically support the monophyly of the Anopheles genus because of an unresolved polytomy between Bironella and A. squamifemur.

Molecular phylogeny of Neotropical bioluminescent beetles (Coleoptera: Elateroidea) in southern and central Brazil.

Science.gov (United States)

Amaral, D T; Arnoldi, F G C; Rosa, S P; Viviani, V R

2014-08-01

Bioluminescence in beetles is found mainly in the Elateroidea superfamily (Elateridae, Lampyridae and Phengodidae). The Neotropical region accounts for the richest diversity of bioluminescent species in the world with about 500 described species, most occurring in the Amazon, Atlantic rainforest and Cerrado (savanna) ecosystems in Brazil. The origin and evolution of bioluminescence, as well as the taxonomic status of several Neotropical taxa in these families remains unclear. In order to contribute to a better understanding of the phylogeny and evolution of bioluminescent Elateroidea we sequenced and analyzed sequences of mitochondrial NADH2 and the nuclear 28S genes and of the cloned luciferase sequences of Brazilian species belonging to the following genera: (Lampyridae) Macrolampis, Photuris, Amydetes, Bicellonycha, Aspisoma, Lucidota, Cratomorphus; (Elateridae) Conoderus, Pyrophorus, Hapsodrilus, Pyrearinus, Fulgeochlizus; and (Phengodidae) Pseudophengodes, Phrixothrix, Euryopa and Brasilocerus. Our study supports a closer phylogenetic relationship between Elateridae and Phengodidae as other molecular studies, in contrast with previous morphologic and molecular studies that clustered Lampyridae/Phengodidae. Molecular data also supported division of the Phengodinae subfamily into the tribes Phengodini and Mastinocerini. The position of the genus Amydetes supports the status of the Amydetinae as a subfamily. The genus Euryopa is included in the Mastinocerini tribe within the Phengodinae/Phengodidae. Copyright © 2013 John Wiley & Sons, Ltd.

Novas espécies de Prioninae e de Cerambycinae (Cerambycidae da Região Neotropical New Neotropical species of Prioninae and Cerambycinae (Cerambycidae

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Maria Helena M. Galileo

2010-03-01

Full Text Available Novas espécies descritas: Hovorelus adiectus sp. nov. (Anacolini da Costa Rica; Stenoeme aguilari sp. nov. do Paraguai e Placoeme wappesi sp. nov. da Bolívia (Oemini; da Bahia, Brasil: Coeloxestia spinosa sp. nov. (Cerambycini, Sphallotrichina; Stizocera debilis sp. nov., Anelaphus bravoi sp. nov. (Elaphidionini e Chydarteres formosus sp. nov. (Trachyderini.New Neotropical species of Prioninae and Cerambycinae (Cerambycidae. New species described: Hovorelus adiectus sp. nov. (Anacolini from Costa Rica; Stenoeme aguilari sp. nov. from Paraguai and Placoeme wappesi sp. nov. from Bolivia (Oemini; from Bahia, Brazil: Coeloxestia spinosa sp. nov. (Cerambycini, Sphallotrichina, Stizocera debilis sp. nov., Anelaphus bravoi sp. nov. (Elaphidionini and Chydarteres formosus sp. nov. (Trachyderini.

Extant diversity and estimated number of Gracillariidae (Lepidoptera species yet to be discovered in the Neotropical region

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Rosângela Brito

Full Text Available ABSTRACT Gracillariidae (Lepidoptera are commonly known by the leaf miner habit found in the larval stage of most species. By using worldwide, public databases on species diversity and DNA sequences available for extant gracillariid species, we determined changes in the rate of taxonomic species descriptions through time, mapped their spatial distributions, examined their phylogenetic diversification, and estimated the number of species yet to be described for the family in the Neotropics. We recovered 185 species, a number that is smaller than that found in any other biogeographic region. However, it was estimated that at least 3875 additional species remain to be described in the region. Phylogenetic diversification showed a pattern of expanding diversity. A few entomologists have been involved with gracillariid taxonomy in the Neotropics, having 39% of the species been described by a single taxonomist. In most of such cases, descriptions were based on the adults only. A few species have been described from biomes known to have some of the greatest diversity on earth, such as the Atlantic Forest. Thus, such a scenario results from low sampling and scarce taxonomic activity that has prevailed for this family of moths in the Neotropics. It may also be associated with their small body size and to the fact that gracillariids do not seem to be attracted to light traps as much as other moths, which make their collection and identification by non experts difficult. We also suggested scientific and political actions that could be adopted to overcome such an unfavorable scenario.

Neogene-dominated diversification in neotropical montane lichens: dating divergence events in the lichen-forming fungal genus Oropogon (Parmeliaceae).

Science.gov (United States)

Leavitt, Steven D; Esslinger, Theodore L; Lumbsch, H Thorsten

2012-11-01

Diversification in neotropical regions has been attributed to both Tertiary geological events and Pleistocene climatic fluctuations. However, the timing and processes driving speciation in these regions remain unexplored in many important groups. Here, we address the timing of diversification in the neotropical lichenized fungal genus Oropogon (Ascomycota) and assess traditional species boundaries. We analyzed sequence data from three loci to assess phenotypically circumscribed Oropogon species from the Oaxacan Highlands, Mexico. We provide a comparison of dated divergence estimates between concatenated gene trees and a calibrated multilocus species-tree using substitution rates for two DNA regions. We also compare estimates from a data set excluding ambiguously aligned regions and a data set including the hyper-variable regions in two ribosomal markers. Phylogenetic reconstructions were characterized by well-supported monophyletic clades corresponding to traditionally circumscribed species, with the exception of a single taxon. Divergence estimates indicate that most diversification of the sampled Oropogon species occurred throughout the Oligocene and Miocene, although diversification of a single closely related clade appears to have occurred during the late Pliocene and into the Pleistocene. Divergence estimates calculated from a data set with ambiguously aligned regions removed were much more recent than those from the full data set. Overall, our analyses place the majority of divergence events of Oropogon species from the Oaxacan Highlands within the Neogene and provide strong evidence that climatic changes during the Pleistocene were not a major factor driving speciation in the lichenized genus Oropogon in neotropical highlands.

Using landscape metrics to model source habitat for Neotropical migrants in the midwestern U.S.

Science.gov (United States)

Peter T. Fauth; Eric J. Gustafson; Kerry N. Rabenold

2000-01-01

Size of a forest patch is a useful predictor of density and reproductive success of Neotropical migratory birds in much of eastern North America. Within these forested landscapes, large forest tracts appear to be sources-fragments in which surpluses of offspring are produced and can potentially colonize new fragments including woodlot sinks where reproduction fails to...

Phylogenetic analysis of Attalea (Arecaceae): insights on the historical biogeography of a recently diversified Neotropical plant group

Science.gov (United States)

Technical Abstract Here we present a dated phylogenetic tree of the neotropical palm genus Attalea (Arecaceae). We used six orthologs from the nuclear WRKY gene family across 98 accessions to address relationships among species and biogeographic hypotheses. Here we found that the formerly recognized...

Electronic emission and electron guns

International Nuclear Information System (INIS)

Roy, Amitava

2010-01-01

This paper reviews the process of electron emission from metal surface. Although electrons move freely in conductors like metals, they normally do not leave the metal without some manipulation. In fact, heating and bombardment are the two primary ways in which electrons are emitted through the use of a heating element behind the cathode (termed thermionic emission) or as a result of bombardment with a beam of electrons, ions, or metastable atoms (termed secondary emission). Another important emission mechanism called Explosive Electron Emission (EEE) is also often used in various High Voltage Pulse Power Systems to generate very high current (few hundreds of kA) pulsed electron beams. The electron gun is the device in that it shoots off a continuous (or pulsed) stream of electrons. A brief idea about the evolution of the electron gun components and their basis of functioning are also discussed. (author)

Landscape Use and Co-Occurrence Patterns of Neotropical Spotted Cats

Science.gov (United States)

Nagy-Reis, Mariana B.; Nichols, James D.; Chiarello, Adriano G.; Ribeiro, Milton Cezar; Setz, Eleonore Z. F.

2017-01-01

Small felids influence ecosystem dynamics through prey and plant population changes. Although most of these species are threatened, they are accorded one of the lowest research efforts of all felids, and we lack basic information about them. Many felids occur in sympatry, where intraguild competition is frequent. Therefore, assessing the role of interspecific interactions along with the relative importance of landscape characteristics is necessary to understand how these species co-occur in space. Here, we selected three morphologically similar and closely related species of small Neotropical cats to evaluate the roles of interspecific interactions, geomorphometry, environmental, and anthropogenic landscape characteristics on their habitat use. We collected data with camera trapping and scat sampling in a large protected Atlantic forest remnant (35,000 ha). Throughout occupancy modeling we investigated whether these species occur together more or less frequently than would be expected by chance, while dealing with imperfect detection and incorporating possible habitat preferences into the models. We used occupancy as a measure of their habitat use. Although intraguild competition can be an important determinant of carnivore assemblages, in our system, we did not find evidence that one species affects the habitat use of the other. Evidence suggested that proximity to the nature reserve (a more protected area) was a more important driver of Neotropical spotted cats’ occurrence than interspecific interactions or geomorphometry and environmental landscape characteristics—even though our entire study area is under some type of protection. This suggests that small felids can be sensitive to the area protection status, emphasizing the importance of maintaining and creating reserves and other areas with elevated protection for the proper management and conservation of the group. PMID:28052073

The Stream-Catchment (StreamCat) and Lake-Catchment ...

Science.gov (United States)

Background/Question/MethodsLake and stream conditions respond to both natural and human-related landscape features. Characterizing these features within contributing areas (i.e., delineated watersheds) of streams and lakes could improve our understanding of how biological conditions vary spatially and improve the use, management, and restoration of these aquatic resources. However, the specialized geospatial techniques required to define and characterize stream and lake watersheds has limited their widespread use in both scientific and management efforts at large spatial scales. We developed the StreamCat and LakeCat Datasets to model, predict, and map the probable biological conditions of streams and lakes across the conterminous US (CONUS). Both StreamCat and LakeCat contain watershed-level characterizations of several hundred natural (e.g., soils, geology, climate, and land cover) and anthropogenic (e.g., urbanization, agriculture, mining, and forest management) landscape features for ca. 2.6 million stream segments and 376,000 lakes across the CONUS, respectively. These datasets can be paired with field samples to provide independent variables for modeling and other analyses. We paired 1,380 stream and 1,073 lake samples from the USEPAs National Aquatic Resource Surveys with StreamCat and LakeCat and used random forest (RF) to model and then map an invertebrate condition index and chlorophyll a concentration, respectively. Results/ConclusionsThe invertebrate

Multiple biomarker responses in Prochilodus lineatus subjected to short-term in situ exposure to streams from agricultural areas in Southern Brazil

Energy Technology Data Exchange (ETDEWEB)

Vieira, Carlos Eduardo Delfino [Laboratório de Ecofisiologia Animal — Departamento de Ciências Fisiológicas, Universidade Estadual de Londrina, Paraná (Brazil); Costa, Patrícia Gomes [Laboratório de Microcontaminantes Orgânicos e Ecotoxicologia — Instituto de Oceanografia, Universidade Federal do Rio Grande, Rio Grande do Sul (Brazil); Lunardelli, Bruna; Fernandes de Oliveira, Luciana [Laboratório de Ecofisiologia Animal — Departamento de Ciências Fisiológicas, Universidade Estadual de Londrina, Paraná (Brazil); Costa Cabrera, Liziara da [Laboratório de Análise de Compostos Orgânicos e Metais — Escola de Química e Alimentos, Universidade Federal do Rio Grande, Rio Grande do Sul (Brazil); Risso, Wagner Ezequiel [Laboratório de Ecofisiologia Animal — Departamento de Ciências Fisiológicas, Universidade Estadual de Londrina, Paraná (Brazil); Primel, Ednei Gilberto [Laboratório de Análise de Compostos Orgânicos e Metais — Escola de Química e Alimentos, Universidade Federal do Rio Grande, Rio Grande do Sul (Brazil); and others

2016-01-15

In order to assess the quality of streams susceptible to contamination by pesticides we apply biochemical and genotoxic biomarkers in the Neotropical fish Prochilodus lineatus submitted to in situ tests. Fish were caged, for 96 h, in two streams located in areas with intensive use of pesticides, the Apertados (AP) and the Jacutinga (JC), and in a small stream (Godoy stream — GD) found inside a forest fragment adjacent to a State Park. Biochemical parameters, such as biotransformation enzymes 7-ethoxyresorufin-O-deethylase (EROD) and glutathione-S-transferase (GST), non-protein thiols (NPSH), lipoperoxidation (LPO), protein carbonylation (PCO) and acetylcholinesterase (AChE) were evaluated in various fish organs, as well as genotoxic biomarkers (damage to DNA and occurrence of micronuclei and erythrocyte nuclear abnormalities). Samples of water and sediment were collected for analysis of metals (Cu, Cr, Pb, Ni, Mn, Cd and Zn), organochloride pesticides, and triazine and glyphosate herbicides. We observed an increase in liver GST activity in fish at AP and gill GST activity in fish at JC. An increase in liver LPO was also observed in fish exposed to AP and JC. The same animals also exhibited increased DNA damage and erythrocyte nuclear abnormalities (ENAs) compared to the fish kept in GD. A number of compounds showed concentrations higher than the permitted levels, in particular, dichlorodiphenyltrichloroethane (DDT), its metabolites dichlorodiphenyldichloroethylene (DDE) and dichlorodiphenyldichloroethane (DDD), hexachlorocyclohexanes (HCH), heptachloride, diclofluanid and aldrins. These pesticides were detected at higher concentrations in water and sediment samples from AP, followed by JC and GD. The Integrated Biomarker Response Index (IBR) indicated that AP and JC (AP: 21.7 > JC: 18.5 > GD: 12.6) have the worst environmental quality. Integrated biomarker analysis revealed that the alterations observed related well with the levels of environmental contaminants

Stage description, new combination and new records of Neotropical Brachycercinae (Ephemeroptera: Caenidae).

Science.gov (United States)

Angeli, Kamila Batista; Salles, Frederico Falcão; Paresque, Roberta; Molineri, Carlos; Lima, Lucas Ramos Costa

2016-03-08

We present taxonomic contributions and new records for Neotropical Brachycercinae based on material from Brazil. We performed a phylogenetic analysis in order to test the relationship between Alloretochus Sun & McCafferty, 2008 and Latineosus Sun & Mc- Cafferty, 2008, and Alloretochus sigillatus was recovered in the Latineosus clade. Therefore, we propose a new combination, Latineosus sigillatus comb. n. The nymph of Latineosus sigillatus is described and is associated with imago through molecular tools. Moreover, Alloretochus peruanicus (Soldán, 1986) is reported for the first time from Brazil.

Movement patterns of three arboreal primates in a Neotropical moist forest explained by LiDAR-estimated canopy structure

NARCIS (Netherlands)

McLean, Kevin A.; Trainor, Anne M.; Asner, Gregory P.; Crofoot, Margaret C.; Hopkins, Mariah E.; Campbell, Christina J.; Martin, Roberta E.; Knapp, David E.; Jansen, Patrick A.

2016-01-01

Context: Many arboreal mammals in Neotropical forests are important seed dispersers that influence the spatial patterns of tree regeneration via their movement patterns, which in turn are determined by the canopy structure of the forest itself. However, the relationship between arboreal mammal

Streaming Pool: reuse, combine and create reactive streams with pleasure

CERN Multimedia

CERN. Geneva

2017-01-01

When connecting together heterogeneous and complex systems, it is not easy to exchange data between components. Streams of data are successfully used in industry in order to overcome this problem, especially in the case of "live" data. Streams are a specialization of the Observer design pattern and they provide asynchronous and non-blocking data flow. The ongoing effort of the ReactiveX initiative is one example that demonstrates how demanding this technology is even for big companies. Bridging the discrepancies of different technologies with common interfaces is already done by the Reactive Streams initiative and, in the JVM world, via reactive-streams-jvm interfaces. Streaming Pool is a framework for providing and discovering reactive streams. Through the mechanism of dependency injection provided by the Spring Framework, Streaming Pool provides a so called Discovery Service. This object can discover and chain streams of data that are technologically agnostic, through the use of Stream IDs. The stream to ...

Interaction between stream temperature, streamflow, and groundwater exchanges in alpine streams

Science.gov (United States)

Constantz, James E.

1998-01-01

Four alpine streams were monitored to continuously collect stream temperature and streamflow for periods ranging from a week to a year. In a small stream in the Colorado Rockies, diurnal variations in both stream temperature and streamflow were significantly greater in losing reaches than in gaining reaches, with minimum streamflow losses occurring early in the day and maximum losses occurring early in the evening. Using measured stream temperature changes, diurnal streambed infiltration rates were predicted to increase as much as 35% during the day (based on a heat and water transport groundwater model), while the measured increase in streamflow loss was 40%. For two large streams in the Sierra Nevada Mountains, annual stream temperature variations ranged from 0° to 25°C. In summer months, diurnal stream temperature variations were 30–40% of annual stream temperature variations, owing to reduced streamflows and increased atmospheric heating. Previous reports document that one Sierra stream site generally gains groundwater during low flows, while the second Sierra stream site may lose water during low flows. For August the diurnal streamflow variation was 11% at the gaining stream site and 30% at the losing stream site. On the basis of measured diurnal stream temperature variations, streambed infiltration rates were predicted to vary diurnally as much as 20% at the losing stream site. Analysis of results suggests that evapotranspiration losses determined diurnal streamflow variations in the gaining reaches, while in the losing reaches, evapotranspiration losses were compounded by diurnal variations in streambed infiltration. Diurnal variations in stream temperature were reduced in the gaining reaches as a result of discharging groundwater of relatively constant temperature. For the Sierra sites, comparison of results with those from a small tributary demonstrated that stream temperature patterns were useful in delineating discharges of bank storage following

Mites of the genus Neharpyrhynchus Fain (Acariformes, Harpirhynchidae from Neotropical birds

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Andre Bochkov

2011-04-01

Full Text Available Three new species of parasitic mites of the genus Neharpyrhynchus Fain (Acariformes, Harpirhynchidae are described from Neotropical birds, N. chlorospingus sp. n. from Chlorospingus pileatus (Passeriformes, Emberizidae from Costa Rica, N. mironovi sp. n. from Dacnys cayana (Passeriformes, Thraupidae and N. tangara sp. n. from Tangara cayana (Thraupidae both from Brazil. Neharpyrhynchus trochilinus (Fain is recorded from 3 new hosts of the family Trochilidae (Apodiformes, Panterpe insignis and Eugenes fulgens from Costa Rica, and Amazilia lactea from Brazil. Emended diagnosis of the genus and a key to species are provided; all records of Neharpyrhynchus species are summarized.

Evidence for the persistence of food web structure after amphibian extirpation in a Neotropical stream.

Science.gov (United States)

Barnum, Thomas R; Drake, John M; Colón-Gaud, Checo; Rugenski, Amanda T; Frauendorf, Therese C; Connelly, Scott; Kilham, Susan S; Whiles, Matt R; Lips, Karen R; Pringle, Catherine M

2015-08-01

Species losses are predicted to simplify food web structure, and disease-driven amphibian declines in Central America offer an opportunity to test this prediction. Assessment of insect community composition, combined with gut content analyses, was used to generate periphyton-insect food webs for a Panamanian stream, both pre- and post-amphibian decline. We then used network analysis to assess the effects of amphibian declines on food web structure. Although 48% of consumer taxa, including many insect taxa, were lost between pre- and post-amphibian decline sampling dates, connectance declined by less than 3%. We then quantified the resilience of food web structure by calculating the number of expected cascading extirpations from the loss of tadpoles. This analysis showed the expected effects of species loss on connectance and linkage density to be more than 60% and 40%, respectively, than were actually observed. Instead, new trophic linkages in the post-decline food web reorganized the food web topology, changing the identity of "hub" taxa, and consequently reducing the effects of amphibian declines on many food web attributes. Resilience of food web attributes was driven by a combination of changes in consumer diets, particularly those of insect predators, as well as the appearance of generalist insect consumers, suggesting that food web structure is maintained by factors independent of the original trophic linkages.

Adaptive landscape and functional diversity of Neotropical cichlids: implications for the ecology and evolution of Cichlinae (Cichlidae; Cichliformes).

Science.gov (United States)

Arbour, J H; López-Fernández, H

2014-11-01

Morphological, lineage and ecological diversity can vary substantially even among closely related lineages. Factors that influence morphological diversification, especially in functionally relevant traits, can help to explain the modern distribution of disparity across phylogenies and communities. Multivariate axes of feeding functional morphology from 75 species of Neotropical cichlid and a stepwise-AIC algorithm were used to estimate the adaptive landscape of functional morphospace in Cichlinae. Adaptive landscape complexity and convergence, as well as the functional diversity of Cichlinae, were compared with expectations under null evolutionary models. Neotropical cichlid feeding function varied primarily between traits associated with ram feeding vs. suction feeding/biting and secondarily with oral jaw muscle size and pharyngeal crushing capacity. The number of changes in selective regimes and the amount of convergence between lineages was higher than expected under a null model of evolution, but convergence was not higher than expected under a similarly complex adaptive landscape. Functional disparity was compatible with an adaptive landscape model, whereas the distribution of evolutionary change through morphospace corresponded with a process of evolution towards a single adaptive peak. The continentally distributed Neotropical cichlids have evolved relatively rapidly towards a number of adaptive peaks in functional trait space. Selection in Cichlinae functional morphospace is more complex than expected under null evolutionary models. The complexity of selective constraints in feeding morphology has likely been a significant contributor to the diversity of feeding ecology in this clade. © 2014 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2014 European Society For Evolutionary Biology.

Genetic Diversity and Phylogenetic Relationships of Coevolving Symbiont-Harboring Insect Trypanosomatids, and Their Neotropical Dispersal by Invader African Blowflies (Calliphoridae

Directory of Open Access Journals (Sweden)

Tarcilla C. Borghesan

2018-02-01

Full Text Available This study is about the inter- and intra-specific genetic diversity of trypanosomatids of the genus Angomonas, and their association with Calliphoridae (blowflies in Neotropical and Afrotropical regions. Microscopic examination of 3,900 flies of various families, mostly Calliphoridae, revealed that 31% of them harbored trypanosomatids. Small subunit rRNA (SSU rRNA barcoding showed that Angomonas predominated (46% over the other common trypanosomatids of blowflies of genera Herpetomonas and Wallacemonas. Among Angomonas spp., A. deanei was much more common than the two-other species, A. desouzai and A. ambiguus. Phylogenetic analyses based on SSU rRNA, glycosomal glyceraldehyde-3-phosphate dehydrogenase (gGAPDH and internal transcribed spacer rDNA (ITS rDNA sequences revealed a marked genetic diversity within A. deanei, which comprised four infraspecific genotypes (Dea1–Dea4, and four corresponding symbiont genotypes (Kcr1–Kcr4. Host and symbiont phylogenies were highly congruent corroborating their co-divergence, consistent with host-symbiont interdependent metabolism and symbiont reduced genomes shaped by a long coevolutionary history. We compared the diversity of Angomonas/symbionts from three genera of blowflies, Lucilia, Chrysomya and Cochliomyia. A. deanei, A. desouzai, and A. ambiguus were found in the three genera of blowflies in South America. In Africa, A. deanei and A. ambiguus were identified in Chrysomya. The absence of A. desouzai in Africa and its presence in Neotropical Cochliomyia and Lucilia suggests parasite spillback of A. desouzai into Chrysomya, which was most likely introduced four decades ago from Africa into the Neotropic. The absence of correlation between parasite diversity and geographic and genetic distances, with identical genotypes of A. deanei found in the Neotropic and Afrotropic, is consistent with disjunct distribution due to the recent human-mediated transoceanic dispersal of Angomonas by Chrysomya. This

Analytic approach to auroral electron transport and energy degradation

International Nuclear Information System (INIS)

Stamnes, K.

1980-01-01

The interaction of a beam of auroral electrons with the atmosphere is described by the linear transport equation, encompassing discrete energy loss, multiple scattering, and secondary electrons. A solution to the transport equation provides the electron intensity as a function of altitude, pitch angle (with respect to the geomagnetic field) and energy. A multi-stream (discrete ordinate) approximation to the transport equation is developed. An analytic solution is obtained in this approximation. The computational scheme obtained by combining the present transport code with the energy degradation method of Swartz (1979) conserves energy identically. The theory provides a framework within which angular distributions can be easily calculated and interpreted. Thus, a detailed study of the angular distributions of 'non-absorbed' electrons (i.e., electrons that have lost just a small fraction of their incident energy) reveals a systematic variation with incident angle and energy, and with penetration depth. The present approach also gives simple yet accurate solutions in low order multi-stream approximations. The accuracy of the four-stream approximation is generally within a few per cent, whereas two-stream results for backscattered mean intensities and fluxes are accurate to within 10-15%. (author)

Relation between Streaming Potential and Streaming Electrification Generated by Streaming of Water through a Sandwich-type Cell

OpenAIRE

Maruyama, Kazunori; Nikaido, Mitsuru; Hara, Yoshinori; Tanizaki, Yoshie

2012-01-01

Both streaming potential and accumulated charge of water flowed out were measured simultaneously using a sandwich-type cell. The voltages generated in divided sections along flow direction satisfied additivity. The sign of streaming potential agreed with that of streaming electrification. The relation between streaming potential and streaming electrification was explained from a viewpoint of electrical double layer in glass-water interface.

Auroral electron acceleration by lower-hybrid waves

International Nuclear Information System (INIS)

Bingham, R.; Bryant, D.A.; Hall, D.S.

1986-01-01

Because the particles and electric fields association with inverted-V electron streams do not have the characteristics expected for acceleration by a quasistatic potential difference, the possiblity that the electrons are stochastically accelerated by waves is investigated. It is demonstrated that the lower hybrid waves seen on auroral field lines have the righ properties to account for the electron acceleration. It is further shown that the lower hybrid wave power measured on auroral field lines can be generated by the streaming ions observed at the boundary of the plasma sheet, and that this wave power is sufficient to account for the electron power observed close to the atmosphere. (author)

Contrasting patterns of Andean diversification among three diverse clades of Neotropical clearwing butterflies.

Science.gov (United States)

Chazot, Nicolas; De-Silva, Donna Lisa; Willmott, Keith R; Freitas, André V L; Lamas, Gerardo; Mallet, James; Giraldo, Carlos E; Uribe, Sandra; Elias, Marianne

2018-04-01

The Neotropical region is the most biodiverse on Earth, in a large part due to the highly diverse tropical Andean biota. The Andes are a potentially important driver of diversification within the mountains and for neighboring regions. We compared the role of the Andes in diversification among three subtribes of Ithomiini butterflies endemic to the Neotropics, Dircennina, Oleriina, and Godyridina. The diversification patterns of Godyridina have been studied previously. Here, we generate the first time-calibrated phylogeny for the largest ithomiine subtribe, Dircennina, and we reanalyze a published phylogeny of Oleriina to test different biogeographic scenarios involving the Andes within an identical framework. We found common diversification patterns across the three subtribes, as well as major differences. In Dircennina and Oleriina, our results reveal a congruent pattern of diversification related to the Andes with an Andean origin, which contrasts with the Amazonian origin and multiple Andean colonizations of Godyridina. In each of the three subtribes, a clade diversified in the Northern Andes at a faster rate. Diversification within Amazonia occurred in Oleriina and Godyridina, while virtually no speciation occurred in Dircennina in this region. Dircennina was therefore characterized by higher diversification rates within the Andes compared to non-Andean regions, while in Oleriina and Godyridina, we found no difference between these regions. Our results and discussion highlight the importance of comparative approaches in biogeographic studies.

New phytotoxic diterpenoids from Vellozia gigantea (Velloziaceae), an endemic neotropical plant living in the endangered Brazilian biome Rupestrian grasslands

Science.gov (United States)

Vellozia gigantea is a rare, ancient and endemic neotropical plant present in the Brazilian Rupestrian grasslands. The dichloromethane extract of V. gigantea adventitious roots was phytotoxic against Lactuca sativa, Agrostis stolonifera and Lemna paucicostata, and showed larvicidal activity against ...

Genetic diversity of Hypostomus ancistroides (Teleostei, Loricariidae from an urban stream

Directory of Open Access Journals (Sweden)

Silvia H. Sofia

2008-01-01

Full Text Available In this study, random amplified polymorphic DNA (RAPD markers were applied to analyze the genetic diversity of samples of the Neotropical catfish Hypostomus ancistroides, collected from four sites (S1, S2, S3 and S4 along an urban stream in Southern Brazil. The 11 primers used in RAPD analysis amplified 147 loci, 76 (51.7% of which were polymorphic. The proportions of polymorphic loci observed in the four samples were: 29.93% (S1, 31.97% (S2, 23.81% (S3 and 38.77% (S4. The average heterozygosity within sampling localities ranged from 0.1230 to 0.1526 and unbiased genetic distances ranged from 0.0253 to 0.0445. AMOVA partitioned 90.85% of the total variation within samples and 9.15% among samples. Excepting for the sample pair S1-S2 (phiST = 0.02784; p > 0.05, all others pairwise phiST values were significantly greater than zero, indicating moderate genetic differentiation among catfish samples from four localities. The relative low levels of genetic variation detected in all groups studied could be related to different factors, including the sedentary habit of these fish, which can be eroding the genetic variation of H. ancistroides from each locality.

Molecular detection of viral agents in free-ranging and captive neotropical felids in Brazil.

Science.gov (United States)

Furtado, Mariana M; Taniwaki, Sueli A; de Barros, Iracema N; Brandão, Paulo E; Catão-Dias, José L; Cavalcanti, Sandra; Cullen, Laury; Filoni, Claudia; Jácomo, Anah T de Almeida; Jorge, Rodrigo S P; Silva, Nairléia Dos Santos; Silveira, Leandro; Ferreira Neto, José S

2017-09-01

We describe molecular testing for felid alphaherpesvirus 1 (FHV-1), carnivore protoparvovirus 1 (CPPV-1), feline calicivirus (FCV), alphacoronavirus 1 (feline coronavirus [FCoV]), feline leukemia virus (FeLV), feline immunodeficiency virus (FIV), and canine distemper virus (CDV) in whole blood samples of 109 free-ranging and 68 captive neotropical felids from Brazil. Samples from 2 jaguars ( Panthera onca) and 1 oncilla ( Leopardus tigrinus) were positive for FHV-1; 2 jaguars, 1 puma ( Puma concolor), and 1 jaguarundi ( Herpairulus yagouaroundi) tested positive for CPPV-1; and 1 puma was positive for FIV. Based on comparison of 103 nucleotides of the UL24-UL25 gene, the FHV-1 sequences were 99-100% similar to the FHV-1 strain of domestic cats. Nucleotide sequences of CPPV-1 were closely related to sequences detected in other wild carnivores, comparing 294 nucleotides of the VP1 gene. The FIV nucleotide sequence detected in the free-ranging puma, based on comparison of 444 nucleotides of the pol gene, grouped with other lentiviruses described in pumas, and had 82.4% identity with a free-ranging puma from Yellowstone Park and 79.5% with a captive puma from Brazil. Our data document the circulation of FHV-1, CPPV-1, and FIV in neotropical felids in Brazil.

Consumer-to-Consumer Electronic Commerce: A Distinct Research Stream

OpenAIRE

Kiku Jones; Lori N.K. Leonard

2007-01-01

Consumer-to-consumer (C2C) e-commerce is a growing area of e-commerce. However, according to a meta-analysis of critical themes of e-commerce, C2C e-commerce was only represented in the area of online auctions (Wareham, Zheng, & Straub, 2005). C2C e-commerce can encompass much more than just auctions. The question then becomes, “is C2C e-commerce a different research area that deserves its own stream of research?†This study adapts constructs from a business-to-consumer (B2C) e-commerce st...

StreamMap: Smooth Dynamic Visualization of High-Density Streaming Points.

Science.gov (United States)

Li, Chenhui; Baciu, George; Han, Yu

2018-03-01

Interactive visualization of streaming points for real-time scatterplots and linear blending of correlation patterns is increasingly becoming the dominant mode of visual analytics for both big data and streaming data from active sensors and broadcasting media. To better visualize and interact with inter-stream patterns, it is generally necessary to smooth out gaps or distortions in the streaming data. Previous approaches either animate the points directly or present a sampled static heat-map. We propose a new approach, called StreamMap, to smoothly blend high-density streaming points and create a visual flow that emphasizes the density pattern distributions. In essence, we present three new contributions for the visualization of high-density streaming points. The first contribution is a density-based method called super kernel density estimation that aggregates streaming points using an adaptive kernel to solve the overlapping problem. The second contribution is a robust density morphing algorithm that generates several smooth intermediate frames for a given pair of frames. The third contribution is a trend representation design that can help convey the flow directions of the streaming points. The experimental results on three datasets demonstrate the effectiveness of StreamMap when dynamic visualization and visual analysis of trend patterns on streaming points are required.

Analyzing indicators of stream health for Minnesota streams

Science.gov (United States)

Singh, U.; Kocian, M.; Wilson, B.; Bolton, A.; Nieber, J.; Vondracek, B.; Perry, J.; Magner, J.

2005-01-01

Recent research has emphasized the importance of using physical, chemical, and biological indicators of stream health for diagnosing impaired watersheds and their receiving water bodies. A multidisciplinary team at the University of Minnesota is carrying out research to develop a stream classification system for Total Maximum Daily Load (TMDL) assessment. Funding for this research is provided by the United States Environmental Protection Agency and the Minnesota Pollution Control Agency. One objective of the research study involves investigating the relationships between indicators of stream health and localized stream characteristics. Measured data from Minnesota streams collected by various government and non-government agencies and research institutions have been obtained for the research study. Innovative Geographic Information Systems tools developed by the Environmental Science Research Institute and the University of Texas are being utilized to combine and organize the data. Simple linear relationships between index of biological integrity (IBI) and channel slope, two-year stream flow, and drainage area are presented for the Redwood River and the Snake River Basins. Results suggest that more rigorous techniques are needed to successfully capture trends in IBI scores. Additional analyses will be done using multiple regression, principal component analysis, and clustering techniques. Uncovering key independent variables and understanding how they fit together to influence stream health are critical in the development of a stream classification for TMDL assessment.

Low frequency waves in streaming quantum dusty plasmas

Science.gov (United States)

Rozina, Ch.; Jamil, M.; Khan, Arroj A.; Zeba, I.; Saman, J.

2017-09-01

The influence of quantum effects on the excitation of two instabilities, namely quantum dust-acoustic and quantum dust-lower-hybrid waves due to the free streaming of ion/dust particles in uniformly magnetized dusty plasmas has been investigated using a quantum hydrodynamic model. We have obtained dispersion relations under some particular conditions applied on streaming ions and two contrastreaming dust particle beams at equilibrium and have analyzed the growth rates graphically. We have shown that with the increase of both the electron number density and the streaming speed of ion there is enhancement in the instability due to the fact that the dense plasma particle system with more energetic species having a high speed results in the increase of the growth rate in the electrostatic mode. The application of this work has been pointed out for laboratory as well as for space dusty plasmas.

Streaming-aware channel utilization improvement for wireless home networks

NARCIS (Netherlands)

Aslam, W.; Lukkien, J.J.

2012-01-01

A wireless network of consumer electronic (CE) devices in a modern home, is typically running streaming services with heterogeneous bandwidth demands. Satisfying these demands offers the challenge of mapping them efficiently onto scarce wireless channel bandwidth. This mapping is supported by the

Relativistic Electron Response to the Combined Magnetospheric Impact of a Coronal Mass Ejection Overlapping with a High-Speed Stream: Van Allen Probes Observations

Science.gov (United States)

Kanekal, S. G.; Baker, D. N.; Henderson, M. G.; Li, W.; Fennell, J. F.; Zheng, Y.; Richardson, I. G.; Jones, A.; Ali, A. F.; Elkington, S. R.;

Hyporheic exchange and fulvic acid redox reactions in an alpine stream/wetland ecosystem, Colorado front range

Science.gov (United States)

Miller, Matthew P.; McKnight, Diane M.; Cory, R.M.; Williams, Mark W.; Runkel, Robert L.

2006-01-01

The influence of hyporheic zone interactions on the redox state of fulvic acids and other redox active species was investigated in an alpine stream and adjacent wetland, which is a more reducing environment. A tracer injection experiment using bromide (Br-) was conducted in the stream system. Simulations with a transport model showed that rates of exchange between the stream and hyporheic zone were rapid (?? ??? 10-3 s -1). Parallel factor analysis of fluorescence spectra was used to quantify the redox state of dissolved fulvic acids. The rate coefficient for oxidation of reduced fulvic acids (?? = 6.5 ?? 10-3 s -1) in the stream indicates that electron-transfer reactions occur over short time scales. The rate coefficients for decay of ammonium (?? = 1.2 ?? 10-3 s-1) and production of nitrate (?? = -1.0 ?? 10-3 s-1) were opposite in sign but almost equal in magnitude. Our results suggest that fulvic acids are involved in rapid electron-transfer processes in and near the stream channel and may be important in determining ecological energy flow at the catchment scale. ?? 2006 American Chemical Society.

STREAM2016: Streaming Requirements, Experience, Applications and Middleware Workshop

Energy Technology Data Exchange (ETDEWEB)

Fox, Geoffrey [Indiana Univ., Bloomington, IN (United States); Jha, Shantenu [Rutgers Univ., New Brunswick, NJ (United States); Ramakrishnan, Lavanya [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

2016-10-01

The Department of Energy (DOE) Office of Science (SC) facilities including accelerators, light sources and neutron sources and sensors that study, the environment, and the atmosphere, are producing streaming data that needs to be analyzed for next-generation scientific discoveries. There has been an explosion of new research and technologies for stream analytics arising from the academic and private sectors. However, there has been no corresponding effort in either documenting the critical research opportunities or building a community that can create and foster productive collaborations. The two-part workshop series, STREAM: Streaming Requirements, Experience, Applications and Middleware Workshop (STREAM2015 and STREAM2016), were conducted to bring the community together and identify gaps and future efforts needed by both NSF and DOE. This report describes the discussions, outcomes and conclusions from STREAM2016: Streaming Requirements, Experience, Applications and Middleware Workshop, the second of these workshops held on March 22-23, 2016 in Tysons, VA. STREAM2016 focused on the Department of Energy (DOE) applications, computational and experimental facilities, as well software systems. Thus, the role of “streaming and steering” as a critical mode of connecting the experimental and computing facilities was pervasive through the workshop. Given the overlap in interests and challenges with industry, the workshop had significant presence from several innovative companies and major contributors. The requirements that drive the proposed research directions, identified in this report, show an important opportunity for building competitive research and development program around streaming data. These findings and recommendations are consistent with vision outlined in NRC Frontiers of Data and National Strategic Computing Initiative (NCSI) [1, 2]. The discussions from the workshop are captured as topic areas covered in this report's sections. The report

The influence of electron inertia on the modulational instability of ion-acoustic waves

International Nuclear Information System (INIS)

Parkes, E.J.

1993-01-01

The influence of electron inertia, ion streaming and weak relativistic effects on the modulational instability of ion-acoustic waves in a collisionless unmagnetized plasma is investigated. The derivative expansion method is used to derive a nonlinear Schroedinger equation, from which an instability criterion is deduced. When electron inertia is ignored, ion streaming and weak relativistic effects have little effect on the instability criterion. It is shown that when electron inertia is taken into account, the instability criterion is sensitive to weakly relativistic ion streaming, but not to the ratio of electron mass to ion mass. (Author)

Interoceanic occurrence of species of Aristocleidus Mueller, 1936 (Monogenoidea: Dactylogyridae) parasitizing the gills of gerreid fishes in the Neotropics

Czech Academy of Sciences Publication Activity Database

Mendoza-Franco, Edgar F.; Violante-González, J.; Roche, D. G.

2009-01-01

Roč. 105, č. 3 (2009), s. 703-708 ISSN 0932-0113 Institutional research plan: CEZ:AV0Z60220518 Keywords : Neotropics * Gerreidae * Aristocleidus * Diapterus * Gerres * host specificity * Isthmus of Panama Subject RIV: GJ - Animal Vermins ; Diseases, Veterinary Medicine Impact factor: 1.721, year: 2009

Temporal Dynamics of Reproduction of the Neotropical Fish, Crenicichla menezesi (Perciformes: Cichlidae

Directory of Open Access Journals (Sweden)

Andréa Soares de Araújo

2012-01-01

Full Text Available The reproductive biology and the gonadal development cycle of the Neotropical cichlid fish, Crenicichla menezesi, is described. This species exhibits sexual dimorphism only during the spawning season. First sexual maturity of females is attained earlier than the males. Both macroscopic and histological investigations of ovaries and testes revealed four stages of gonadal maturation. Mean batch fecundity of females was 372 (±10,41 of mature oocytes. This species is a partial spawner, with an extended spawning period. Monthly values of GSI and the condition factor are negatively correlated during the gonadal development cycle of this species.

Shifting stream planform state decreases stream productivity yet increases riparian animal production

Science.gov (United States)

Venarsky, Michael P.; Walters, David M.; Hall, Robert O.; Livers, Bridget; Wohl, Ellen

2018-01-01

In the Colorado Front Range (USA), disturbance history dictates stream planform. Undisturbed, old-growth streams have multiple channels and large amounts of wood and depositional habitat. Disturbed streams (wildfires and logging tested how these opposing stream states influenced organic matter, benthic macroinvertebrate secondary production, emerging aquatic insect flux, and riparian spider biomass. Organic matter and macroinvertebrate production did not differ among sites per unit area (m−2), but values were 2 ×–21 × higher in undisturbed reaches per unit of stream valley (m−1 valley) because total stream area was higher in undisturbed reaches. Insect emergence was similar among streams at the per unit area and per unit of stream valley. However, rescaling insect emergence to per meter of stream bank showed that the emerging insect biomass reaching the stream bank was lower in undisturbed sites because multi-channel reaches had 3 × more stream bank than single-channel reaches. Riparian spider biomass followed the same pattern as emerging aquatic insects, and we attribute this to bottom-up limitation caused by the multi-channeled undisturbed sites diluting prey quantity (emerging insects) reaching the stream bank (riparian spider habitat). These results show that historic landscape disturbances continue to influence stream and riparian communities in the Colorado Front Range. However, these legacy effects are only weakly influencing habitat-specific function and instead are primarily influencing stream–riparian community productivity by dictating both stream planform (total stream area, total stream bank length) and the proportional distribution of specific habitat types (pools vs riffles).

Leaf litter breakdown rates and associated fauna of native and exotic trees used in Neotropical Riparia Reforestation

International Nuclear Information System (INIS)

Gutierrez Isaza, Nataly; Blanco, Juan Felipe

2014-01-01

A signature of globalization is the prevalence of exotic trees along reforested urban and rural riparian zones in the neotropics, but little is known about the instream processing of its leaf litter. In this study, leaf litter breakdown rates were measured during 35 days using mesh bags within a reference headwater stream for seven exotic and three native tree species commonly used in urban and rural reforestation. Artocarpus altilis, Schefflera actinophylla and Terminalia catappa scored the highest mass loss rates (>85 %; mean life: t50 <15 d), while Cecropia sp. and Cespedesia macrophylla (mass loss =36 and 15 %; t50 =58 and 172 d, respectively) scored the lowest rates. However, a broad range of rates was observed among the ten species studied. The carbon to phosphorus ratio (c:p) and toughness of the leaf litter were the best predictors of breakdown rates. However, these leaf properties were not correlated with the very low values of macro invertebrates abundance and diversity, and the few morpho classified as shredders. Therefore physical rather than biological controls seem to best explain the observed variability of mass loss rates, and thus slow decomposing leaf litter species seems to provide a habitat rather than a food resource, particularly to collectors. This study suggests that riparian reforestation will propagate species-specific ecological influences on instream processes such as leaf litter processing depending on leaf quality properties, therefore ecosystem-wide influences should be considered for improving reforestation strategies. Future studies should test for differences in breakdown rates and colonization by macro invertebrates relative for leaf litter species origin (native vs. exotic).

Effect of the riparian vegetation removal on the trophic network of Neotropical stream fish assemblage

Directory of Open Access Journals (Sweden)

Pedro Sartori Manoel

2018-02-01

Full Text Available The study of the diet of fish is an important tool to assess different levels of environmental degradation, since the availability of food in the environment is a key factor for the fish occurrence. The removal of riparian vegetation usually degrades environmental quality, as this vegetation has an important role in providing energy to the ecosystem. This study investigates the effects of the removal of riparian vegetation on the fish assemblage trophic network. The study was carried out in two stretches of a southeastern Brazilian stream, one in a forest fragment and another in a pasture, during the wet and dry seasons of 2014. We analyzed the items consumed by each fish species using the frequency of occurrence and area of each item, which were combined to calculate the alimentary index, which was used to determine the food niche overlap of the fish and the specialization index of the trophic network. Aquatic Hexapoda, vegetal debris and organic matter dominated the trophic network of the two stretches. We detected higher values of food niche overlap in the forested stretch and more complex trophic networks in the pasture stretch. We found few seasonal variations in the items consumed and calculated indices in both stretches studied. The presence of grass on the banks in the pasture stretch and the importation of food resources from the upstream area may have provided a higher diversity of resources and consequently showed a more complex trophic network when compared to the forested stretch.

Comparative phylogeography: concepts, methods and general patterns in neotropical birds

International Nuclear Information System (INIS)

Arbelaez Cortes, Enrique

2012-01-01

Understanding the patterns and processes involved in intraspecific lineages diversification in time and space is the aim of phylogeography. The comparison of those phylogeographic patterns among co-distributed species shows insights of a community history. Here I review the concepts and methodologies of comparative phylogeography, an active research field that has heterogeneous analytical methods. In order to present a framework for phylogeography in the neotropics, I comment the general phylogeographic patterns of the birds from this region. this review is based on more than 100 studies conducted during the last 25 years and indicate that despite different co-distributed species seem to share some points in their phylogeographic pattern they have idiosyncratic aspects, indicating an unique history for each one.

Shifting stream planform state decreases stream productivity yet increases riparian animal production

Science.gov (United States)

Venarsky, Michael P.; Walters, David M.; Hall, Robert O.; Livers, Bridget; Wohl, Ellen

2018-01-01

In the Colorado Front Range (USA), disturbance history dictates stream planform. Undisturbed, old-growth streams have multiple channels and large amounts of wood and depositional habitat. Disturbed streams (wildfires and logging production, emerging aquatic insect flux, and riparian spider biomass. Organic matter and macroinvertebrate production did not differ among sites per unit area (m−2), but values were 2 ×–21 × higher in undisturbed reaches per unit of stream valley (m−1 valley) because total stream area was higher in undisturbed reaches. Insect emergence was similar among streams at the per unit area and per unit of stream valley. However, rescaling insect emergence to per meter of stream bank showed that the emerging insect biomass reaching the stream bank was lower in undisturbed sites because multi-channel reaches had 3 × more stream bank than single-channel reaches. Riparian spider biomass followed the same pattern as emerging aquatic insects, and we attribute this to bottom-up limitation caused by the multi-channeled undisturbed sites diluting prey quantity (emerging insects) reaching the stream bank (riparian spider habitat). These results show that historic landscape disturbances continue to influence stream and riparian communities in the Colorado Front Range. However, these legacy effects are only weakly influencing habitat-specific function and instead are primarily influencing stream–riparian community productivity by dictating both stream planform (total stream area, total stream bank length) and the proportional distribution of specific habitat types (pools vs riffles).

Two-stream Stability Properties of the Return-Current Layer for Intense Ion Beam Propagation Through Background Plasma

International Nuclear Information System (INIS)

Startsev, Edward A.; Davidson, Ronald C.; Dorf, Mikhail

2009-01-01

When an ion beam with sharp edge propagates through a background plasma, its current is neutralized by the plasma return current everywhere except at the beam edge over a characteristic transverse distance Δx perpendicular ∼ (delta) pe , where (delta) pe = c/ω pe is the collisionless skin depth, and ω pe is the electron plasma frequency. Because the background plasma electrons neutralizing the ion beam current inside the beam are streaming relative to the background plasma electrons outside the beam, the background plasma can support a two-stream surface-mode excitation. Such surface modes have been studied previously assuming complete charge and current neutralization, and have been shown to be strongly unstable. In this paper we study the detailed stability properties of this two-stream surface mode for an electron flow velocity profile self-consistently driven by the ion beam. In particular, it is shown that the self-magnetic field generated inside the unneutralized current layer, which has not been taken into account previously, completely eliminates the instability

ADAPTIVE STREAMING OVER HTTP (DASH UNTUK APLIKASI VIDEO STREAMING

Directory of Open Access Journals (Sweden)

I Made Oka Widyantara

2015-12-01

Full Text Available This paper aims to analyze Internet-based streaming video service in the communication media with variable bit rates. The proposed scheme on Dynamic Adaptive Streaming over HTTP (DASH using the internet network that adapts to the protocol Hyper Text Transfer Protocol (HTTP. DASH technology allows a video in the video segmentation into several packages that will distreamingkan. DASH initial stage is to compress the video source to lower the bit rate video codec uses H.26. Video compressed further in the segmentation using MP4Box generates streaming packets with the specified duration. These packages are assembled into packets in a streaming media format Presentation Description (MPD or known as MPEG-DASH. Streaming video format MPEG-DASH run on a platform with the player bitdash teritegrasi bitcoin. With this scheme, the video will have several variants of the bit rates that gave rise to the concept of scalability of streaming video services on the client side. The main target of the mechanism is smooth the MPEG-DASH streaming video display on the client. The simulation results show that the scheme based scalable video streaming MPEG-DASH able to improve the quality of image display on the client side, where the procedure bufering videos can be made constant and fine for the duration of video views

DNA fingerprinting validates seed dispersal curves from observational studies in the neotropical legume parkia.

Science.gov (United States)

Heymann, Eckhard W; Lüttmann, Kathrin; Michalczyk, Inga M; Saboya, Pedro Pablo Pinedo; Ziegenhagen, Birgit; Bialozyt, Ronald

2012-01-01

Determining the distances over which seeds are dispersed is a crucial component for examining spatial patterns of seed dispersal and their consequences for plant reproductive success and population structure. However, following the fate of individual seeds after removal from the source tree till deposition at a distant place is generally extremely difficult. Here we provide a comparison of observationally and genetically determined seed dispersal distances and dispersal curves in a Neotropical animal-plant system. In a field study on the dispersal of seeds of three Parkia (Fabaceae) species by two Neotropical primate species, Saguinus fuscicollis and Saguinus mystax, in Peruvian Amazonia, we observationally determined dispersal distances. These dispersal distances were then validated through DNA fingerprinting, by matching DNA from the maternally derived seed coat to DNA from potential source trees. We found that dispersal distances are strongly right-skewed, and that distributions obtained through observational and genetic methods and fitted distributions do not differ significantly from each other. Our study showed that seed dispersal distances can be reliably estimated through observational methods when a strict criterion for inclusion of seeds is observed. Furthermore, dispersal distances produced by the two primate species indicated that these primates fulfil one of the criteria for efficient seed dispersers. Finally, our study demonstrated that DNA extraction methods so far employed for temperate plant species can be successfully used for hard-seeded tropical plants.

Long-term carbon loss in fragmented Neotropical forests.

Science.gov (United States)

Pütz, Sandro; Groeneveld, Jürgen; Henle, Klaus; Knogge, Christoph; Martensen, Alexandre Camargo; Metz, Markus; Metzger, Jean Paul; Ribeiro, Milton Cezar; de Paula, Mateus Dantas; Huth, Andreas

2014-10-07

Tropical forests play an important role in the global carbon cycle, as they store a large amount of carbon (C). Tropical forest deforestation has been identified as a major source of CO2 emissions, though biomass loss due to fragmentation--the creation of additional forest edges--has been largely overlooked as an additional CO2 source. Here, through the combination of remote sensing and knowledge on ecological processes, we present long-term carbon loss estimates due to fragmentation of Neotropical forests: within 10 years the Brazilian Atlantic Forest has lost 69 (±14) Tg C, and the Amazon 599 (±120) Tg C due to fragmentation alone. For all tropical forests, we estimate emissions up to 0.2 Pg C y(-1) or 9 to 24% of the annual global C loss due to deforestation. In conclusion, tropical forest fragmentation increases carbon loss and should be accounted for when attempting to understand the role of vegetation in the global carbon balance.

Continuity-Aware Scheduling Algorithm for Scalable Video Streaming

Directory of Open Access Journals (Sweden)

Atinat Palawan

2016-05-01

Full Text Available The consumer demand for retrieving and delivering visual content through consumer electronic devices has increased rapidly in recent years. The quality of video in packet networks is susceptible to certain traffic characteristics: average bandwidth availability, loss, delay and delay variation (jitter. This paper presents a scheduling algorithm that modifies the stream of scalable video to combat jitter. The algorithm provides unequal look-ahead by safeguarding the base layer (without the need for overhead of the scalable video. The results of the experiments show that our scheduling algorithm reduces the number of frames with a violated deadline and significantly improves the continuity of the video stream without compromising the average Y Peek Signal-to-Noise Ratio (PSNR.

Akamai Streaming

OpenAIRE

ECT Team, Purdue

2007-01-01

Akamai offers world-class streaming media services that enable Internet content providers and enterprises to succeed in today's Web-centric marketplace. They deliver live event Webcasts (complete with video production, encoding, and signal acquisition services), streaming media on demand, 24/7 Webcasts and a variety of streaming application services based upon their EdgeAdvantage.

The Midwest Stream Quality Assessment—Influences of human activities on streams

Science.gov (United States)

Van Metre, Peter C.; Mahler, Barbara J.; Carlisle, Daren M.; Coles, James F.

2018-04-16

Healthy streams and the fish and other organisms that live in them contribute to our quality of life. Extensive modification of the landscape in the Midwestern United States, however, has profoundly affected the condition of streams. Row crops and pavement have replaced grasslands and woodlands, streams have been straightened, and wetlands and fields have been drained. Runoff from agricultural and urban land brings sediment and chemicals to streams. What is the chemical, physical, and biological condition of Midwestern streams? Which physical and chemical stressors are adversely affecting biological communities, what are their origins, and how might we lessen or avoid their adverse effects?In 2013, the U.S. Geological Survey (USGS) conducted the Midwest Stream Quality Assessment to evaluate how human activities affect the biological condition of Midwestern streams. In collaboration with the U.S. Environmental Protection Agency National Rivers and Streams Assessment, the USGS sampled 100 streams, chosen to be representative of the different types of watersheds in the region. Biological condition was evaluated based on the number and diversity of fish, algae, and invertebrates in the streams. Changes to the physical habitat and chemical characteristics of the streams—“stressors”—were assessed, and their relation to landscape factors and biological condition was explored by using mathematical models. The data and models help us to better understand how the human activities on the landscape are affecting streams in the region.

Plant diversity patterns in neotropical dry forests and their conservation implications.

Science.gov (United States)

Banda-R, Karina; Delgado-Salinas, Alfonso; Dexter, Kyle G; Linares-Palomino, Reynaldo; Oliveira-Filho, Ary; Prado, Darién; Pullan, Martin; Quintana, Catalina; Riina, Ricarda; Rodríguez M, Gina M; Weintritt, Julia; Acevedo-Rodríguez, Pedro; Adarve, Juan; Álvarez, Esteban; Aranguren B, Anairamiz; Arteaga, Julián Camilo; Aymard, Gerardo; Castaño, Alejandro; Ceballos-Mago, Natalia; Cogollo, Álvaro; Cuadros, Hermes; Delgado, Freddy; Devia, Wilson; Dueñas, Hilda; Fajardo, Laurie; Fernández, Ángel; Fernández, Miller Ángel; Franklin, Janet; Freid, Ethan H; Galetti, Luciano A; Gonto, Reina; González-M, Roy; Graveson, Roger; Helmer, Eileen H; Idárraga, Álvaro; López, René; Marcano-Vega, Humfredo; Martínez, Olga G; Maturo, Hernán M; McDonald, Morag; McLaren, Kurt; Melo, Omar; Mijares, Francisco; Mogni, Virginia; Molina, Diego; Moreno, Natalia Del Pilar; Nassar, Jafet M; Neves, Danilo M; Oakley, Luis J; Oatham, Michael; Olvera-Luna, Alma Rosa; Pezzini, Flávia F; Dominguez, Orlando Joel Reyes; Ríos, María Elvira; Rivera, Orlando; Rodríguez, Nelly; Rojas, Alicia; Särkinen, Tiina; Sánchez, Roberto; Smith, Melvin; Vargas, Carlos; Villanueva, Boris; Pennington, R Toby

2016-09-23

Seasonally dry tropical forests are distributed across Latin America and the Caribbean and are highly threatened, with less than 10% of their original extent remaining in many countries. Using 835 inventories covering 4660 species of woody plants, we show marked floristic turnover among inventories and regions, which may be higher than in other neotropical biomes, such as savanna. Such high floristic turnover indicates that numerous conservation areas across many countries will be needed to protect the full diversity of tropical dry forests. Our results provide a scientific framework within which national decision-makers can contextualize the floristic significance of their dry forest at a regional and continental scale. Copyright © 2016, American Association for the Advancement of Science.

Establishing quantitative habitat targets for a "Critically Endangered" neotropical migrant (golden-cheeked warbler Dendroica chrysoparia) during the non-breeding season

Science.gov (United States)

David I. King; Carlin C. Chandler; John H. Rappole; Richard B. Chandler; David W. Mehlman

2012-01-01

The Golden-cheeked Warbler Dendroica chrysoparia is a federally endangered Neotropical migrant that inhabits montane pine-oak forests in Mexico and northern Central America during the non-breeding season. Although it is known that Golden-cheeked Warblers are closely associated with ‘encino’ oaks (...

Analysis of hydraulic characteristics for stream diversion in small stream

Energy Technology Data Exchange (ETDEWEB)

Ahn, Sang-Jin; Jun, Kye-Won [Chungbuk National University, Cheongju(Korea)

2001-10-31

This study is the analysis of hydraulic characteristics for stream diversion reach by numerical model test. Through it we can provide the basis data in flood, and in grasping stream flow characteristics. Analysis of hydraulic characteristics in Seoknam stream were implemented by using computer model HEC-RAS(one-dimensional model) and RMA2(two-dimensional finite element model). As a result we became to know that RMA2 to simulate left, main channel, right in stream is more effective method in analysing flow in channel bends, steep slope, complex bed form effect stream flow characteristics, than HEC-RAS. (author). 13 refs., 3 tabs., 5 figs.

Conservation value and permeability of neotropical oil palm landscapes for orchid bees.

Directory of Open Access Journals (Sweden)

George Livingston

Full Text Available The proliferation of oil palm plantations has led to dramatic changes in tropical landscapes across the globe. However, relatively little is known about the effects of oil palm expansion on biodiversity, especially in key ecosystem-service providing organisms like pollinators. Rapid land use change is exacerbated by limited knowledge of the mechanisms causing biodiversity decline in the tropics, particularly those involving landscape features. We examined these mechanisms by undertaking a survey of orchid bees, a well-known group of Neotropical pollinators, across forest and oil palm plantations in Costa Rica. We used chemical baits to survey the community in four regions: continuous forest sites, oil palm sites immediately adjacent to forest, oil palm sites 2 km from forest, and oil palm sites greater than 5 km from forest. We found that although orchid bees are present in all environments, orchid bee communities diverged across the gradient, and community richness, abundance, and similarity to forest declined as distance from forest increased. In addition, mean phylogenetic distance of the orchid bee community declined and was more clustered in oil palm. Community traits also differed with individuals in oil palm having shorter average tongue length and larger average geographic range size than those in the forest. Our results indicate two key features about Neotropical landscapes that contain oil palm: 1 oil palm is selectively permeable to orchid bees and 2 orchid bee communities in oil palm have distinct phylogenetic and trait structure compared to communities in forest. These results suggest that conservation and management efforts in oil palm-cultivating regions should focus on landscape features.

The metaphors we stream by: Making sense of music streaming

OpenAIRE

Hagen, Anja Nylund

2016-01-01

In Norway music-streaming services have become mainstream in everyday music listening. This paper examines how 12 heavy streaming users make sense of their experiences with Spotify and WiMP Music (now Tidal). The analysis relies on a mixed-method qualitative study, combining music-diary self-reports, online observation of streaming accounts, Facebook and last.fm scrobble-logs, and in-depth interviews. By drawing on existing metaphors of Internet experiences we demonstrate that music-streaming...

Combined phenomena of beam-beam and beam-electron cloud interactionsin circular e^{+}e^{-} colliders

Directory of Open Access Journals (Sweden)

Kazuhito Ohmi

2002-10-01

Full Text Available An electron cloud causes various effects in high intensity positron storage rings. The positron beam and the electron cloud can be considered a typical two-stream system with a certain plasma frequency. Beam-beam interaction is another important effect for high luminosity circular colliders. Colliding two beams can be considered as a two-stream system with another plasma frequency. We study the combined phenomena of the beam-electron cloud and beam-beam interactions from a viewpoint of two complex two-stream effects with two plasma frequencies.

Conservation challenges for the Austral and Neotropical America section.

Science.gov (United States)

Ceballos, Gerardo; Vale, Mariana M; Bonacic, Cristian; Calvo-Alvarado, Julio; List, Rurik; Bynum, Nora; Medellín, Rodrigo A; Simonetti, Javier A; Rodríguez, Jon Paul

2009-08-01

The Austral and Neotropical America (ANA) section of the Society for Conservation Biology includes a vast territory with some of the largest relatively pristine ecosystems in the world. With more than 573 million people, the economic growth of the region still depends strongly on natural resource exploitation and still has high rates of environmental degradation and biodiversity loss. A survey among the ANA section membership, with more than 700 members, including most of the section's prominent ecologists and conservationists, indicates that lack of capacity building for conservation, corruption, and threats such as deforestation and illegal trade of species, are among the most urgent problems that need to be addressed to improve conservation in the region. There are, however, strong universities and ecology groups taking the lead in environmental research and conservation, a most important issue to enhance the ability of the region to solve conservation and development conflicts.

Two-stream instabilities from the lower-hybrid frequency to the electron cyclotron frequency: application to the front of quasi-perpendicular shocks

Directory of Open Access Journals (Sweden)

L. Muschietti

2017-09-01

Full Text Available Quasi-perpendicular supercritical shocks are characterized by the presence of a magnetic foot due to the accumulation of a fraction of the incoming ions that is reflected by the shock front. There, three different plasma populations coexist (incoming ion core, reflected ion beam, electrons and can excite various two-stream instabilities (TSIs owing to their relative drifts. These instabilities represent local sources of turbulence with a wide frequency range extending from the lower hybrid to the electron cyclotron. Their linear features are analyzed by means of both a dispersion study and numerical PIC simulations. Three main types of TSI and correspondingly excited waves are identified: i. Oblique whistlers due to the (so-called fast relative drift between reflected ions/electrons; the waves propagate toward upstream away from the shock front at a strongly oblique angle (θ ∼ 50° to the ambient magnetic field Bo, have frequencies a few times the lower hybrid, and have wavelengths a fraction of the ion inertia length c∕ωpi. ii. Quasi-perpendicular whistlers due to the (so-called slow relative drift between incoming ions/electrons; the waves propagate toward the shock ramp at an angle θ a few degrees off 90°, have frequencies around the lower hybrid, and have wavelengths several times the electron inertia length c∕ωpe. iii. Extended Bernstein waves which also propagate in the quasi-perpendicular domain, yet are due to the (so-called fast relative drift between reflected ions/electrons; the instability is an extension of the electron cyclotron drift instability (normally strictly perpendicular and electrostatic and produces waves with a magnetic component which have frequencies close to the electron cyclotron as well as wavelengths close to the electron gyroradius and which propagate toward upstream. Present results are compared with previous works in order to stress some features not previously analyzed and to define a more

On the wake structure in streaming complex plasmas

International Nuclear Information System (INIS)

Ludwig, Patrick; Kählert, Hanno; Bonitz, Michael; Miloch, Wojciech J

2012-01-01

The theoretical description of complex (dusty) plasmas requires multiscale concepts that adequately incorporate the correlated interplay of streaming electrons and ions, neutrals and dust grains. Knowing the effective dust-dust interaction, the multiscale problem can be effectively reduced to a one-component plasma model of the dust subsystem. The goal of this paper is a systematic evaluation of the electrostatic potential distribution around a dust grain in the presence of a streaming plasma environment by means of two complementary approaches: (i) a high-precision computation of the dynamically screened Coulomb potential from the dynamic dielectric function and (ii) full 3D particle-in-cell simulations, which self-consistently include dynamical grain charging and nonlinear effects. The range of applicability of these two approaches is addressed. (paper)

Neotropical Siluriformes as a Model for Insights on Determining Biodiversity of Animal Groups.

Directory of Open Access Journals (Sweden)

Renata Rúbia Ota

Full Text Available We performed an analysis of the descriptions of new species of Neotropical Siluriformes (catfishes to estimate the number of new species that remain to be described for a complete knowledge on biodiversity of this order, to verify the effectiveness of taxonomic support, and to identify trends and present relevant information for future policies. We conducted a literature review of species descriptions between January 1990 and August 2014. The following metadata were recorded from each article: year of publication, number of species, journal and impact factor, family(s of the described species, number of authors, age of the authors and coauthors, country of the first author's institution and ecoregion of the type-locality. From accumulation of descriptions, we built an estimate model for number of species remaining to be described. We found 595 described species in 402 articles. The data demonstrated that there has been an increased understanding of the diversity of Siluriformes over the last 25 years in the Neotropical region, although 35% of the species still remain to be described. The model estimated that with the current trends and incentives, the biodiversity will be known in almost seven decades. We have reinforced the idea that greater joint efforts should be made by society and the scientific community to obtain this knowledge in a shorter period of time through enhanced programs for promoting science, training and the advancement of professionals before undiscovered species become extinct. The model built in this study can be used for similar estimates of other groups of animals.

Nitrogen use strategies of seedlings from neotropical tree species of distinct successional groups.

Science.gov (United States)

Oliveira, Halley Caixeta; da Silva, Ligia Maria Inocêncio; de Freitas, Letícia Dias; Debiasi, Tatiane Viegas; Marchiori, Nidia Mara; Aidar, Marcos Pereira Marinho; Bianchini, Edmilson; Pimenta, José Antonio; Stolf-Moreira, Renata

2017-05-01

Few studies have analyzed the strategies of neotropical tree seedlings for absorbing, translocating and assimilating the nitrogen. Here, we compared the nitrogen use strategies of seedlings from six tree species that are native to the Brazilian Atlantic Forest and that belong to different successional groups: Trema micrantha, Heliocarpus popayanensis and Cecropia pachystachya (pioneers), Cariniana estrellensis, Eugenia brasiliensis and Guarea kunthiana (non-pioneers). The effects of cultivating seedlings with nitrate or ammonium on the growth, physiology and nitrogen metabolism were analyzed. Nitrate-grown pioneer species had much higher leaf nitrate reductase activity than non-pioneer ones, but non-pioneer seedlings were also able to use nitrate as a nitrogen source. In addition to this remarkable difference between the groups in the capacity for leaf nitrate assimilation, substantial variations in the nitrogen use strategies were observed within the successional classes. Differently from the other non-pioneers, the canopy species C. estrellensis seemed to assimilate nitrate mainly in the leaves. Morphophysiological analyses showed a gradient of ammonium toxicity response, with E. brasiliensis as the most tolerant species, and T. micrantha and H. popayanensis as the most sensitive ones. Guarea kunthiana showed a relatively low tolerance to ammonium and an unusual high translocation of this cation in the xylem sap. In contrast to the other pioneers, C. pachystachya had a high plasticity in the use of nitrogen sources. Overall, these results suggest that nitrogen use strategies of neotropical tree seedlings were not determined solely by their successional position. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

The complete mitochondrial genome of the threatened Neotropical catfish Lophiosilurus alexandri (Silurifomes: Pseudopimelodidae and phylogenomic analysis indicate monophyly of Pimelodoidea

Directory of Open Access Journals (Sweden)

Daniel Cardoso Carvalho

Full Text Available Abstract Lophiosilurus alexandri is an endemic catfish from the São Francisco River Basin (Brazil popularly known as pacamã, which has economic potential for aquaculture farming. The mitochondrial genome was sequenced for the threatened Neotropical catfish L. alexandri. Assembly into scaffolds using MIRA and MITObim software produced the whole, circularized mitochondrial genome, which comprises 16,445 bp and presents the typical gene arrangement of Teleostei mitochondria. A phylogenomic analysis was performed after the concatenation of all proteins obtained from whole mitogenomes of 20 Siluriformes and two outgroups. The results confirmed the monophyly of nine families of catfishes and also clustered L. alexandri as a sister group to the family Pimelodidae, thus confirming the monophyly of the superfamily Pimelodoidea. This is the first mitochondrial phylogenomics study for Pimelodoidea and the first mitogenome described for the Pseudopimelodidae family, representing an important resource for phylogeography, evolutionary biology, and conservation genetics studies in Neotropical fishes.

Are Isomeric Alkenes Used in Species Recognition among Neo-Tropical Stingless Bees (Melipona Spp).

Science.gov (United States)

Martin, Stephen J; Shemilt, Sue; da S Lima, Cândida B; de Carvalho, Carlos A L

2017-12-01

Our understanding of the role of cuticular hydrocarbons (CHC) in recognition is based largely on temperate ant species and honey bees. The stingless bees remain relatively poorly studied, despite being the largest group of eusocial bees, comprising more than 400 species in some 60 genera. The Meliponini and Apini diverged between 80-130 Myr B.P. so the evolutionary trajectories that shaped the chemical communication systems in ants, honeybees and stingless bees may be very different. The aim of this study was to study if a unique species CHC signal existed in Neotropical stingless bees, as has been shown for many temperate species, and what compounds are involved. This was achieved by collecting CHC data from 24 colonies belonging to six species of Melipona from North-Eastern Brazil and comparing the results with previously published CHC studies on Melipona. We found that each of the eleven Melipona species studied so far each produced a unique species CHC signal based around their alkene isomer production. A remarkable number of alkene isomers, up to 25 in M. asilvai, indicated the diversification of alkene positional isomers among the stingless bees. The only other group to have really diversified in alkene isomer production are the primitively eusocial Bumblebees (Bombus spp), which are the sister group of the stingless bees. Furthermore, among the eleven Neotropical Melipona species we could detect no effect of the environment on the proportion of alkane production as has been suggested for some other species.

DNA Fingerprinting Validates Seed Dispersal Curves from Observational Studies in the Neotropical Legume Parkia

Science.gov (United States)

Heymann, Eckhard W.; Lüttmann, Kathrin; Michalczyk, Inga M.; Saboya, Pedro Pablo Pinedo; Ziegenhagen, Birgit; Bialozyt, Ronald

2012-01-01

Background Determining the distances over which seeds are dispersed is a crucial component for examining spatial patterns of seed dispersal and their consequences for plant reproductive success and population structure. However, following the fate of individual seeds after removal from the source tree till deposition at a distant place is generally extremely difficult. Here we provide a comparison of observationally and genetically determined seed dispersal distances and dispersal curves in a Neotropical animal-plant system. Methodology/Principal Findings In a field study on the dispersal of seeds of three Parkia (Fabaceae) species by two Neotropical primate species, Saguinus fuscicollis and Saguinus mystax, in Peruvian Amazonia, we observationally determined dispersal distances. These dispersal distances were then validated through DNA fingerprinting, by matching DNA from the maternally derived seed coat to DNA from potential source trees. We found that dispersal distances are strongly right-skewed, and that distributions obtained through observational and genetic methods and fitted distributions do not differ significantly from each other. Conclusions/Significance Our study showed that seed dispersal distances can be reliably estimated through observational methods when a strict criterion for inclusion of seeds is observed. Furthermore, dispersal distances produced by the two primate species indicated that these primates fulfil one of the criteria for efficient seed dispersers. Finally, our study demonstrated that DNA extraction methods so far employed for temperate plant species can be successfully used for hard-seeded tropical plants. PMID:22514748

The correlations between certain features of the journal Neotropical Ichthyology and its impact factor: a comparative analysis at the thematic and national levels

Directory of Open Access Journals (Sweden)

Sabrina Menezes

Full Text Available The present article analyzes the relationship between characteristics of the journal Neotropical Ichthyology and its impact factor (IF between 2006 and 2011 using bibliometric descriptive quantitative methods. To perform this analysis, two samples of journals included in Journal Citation Reports (JCR were studied. One sample was composed of journals classified within the subject of zoology, and the other contained journals from different areas published in Brazil. The instrument used for data collection was a database created in Microsoft Excel 2007 and the Statistical Package for the Social Sciences (SPSS version 18. The results show that despite its short history, Neotropical Ichthyologyhas exhibited a distinctive impact, as manifested in a significant progression in the IF of this journal in the field of zoology during the investigated period.

Allometry of a neotropical palm, Euterpe edulis Mart. Alometria de uma palmeira Neotropical, Euterpe edulis Mart

Directory of Open Access Journals (Sweden)

Luciana F. Alves

2004-06-01

Full Text Available The stem allometry (stem diameter vs. tree height of a Neotropical palm (Euterpe edulis found in rain and seasonal forest of Southeastern Brazil was examined. Observed height-diameter relationships along the stem (diameter at ground level, (dgl, and diameter at breast height (dbh were compared to three theoretical stability mechanical models: elastic similarity, stress similarity and geometric similarity. Slopes of log-transformed height-diameter relationships did not lie near those predicted by any stability mechanical models. Significant differences in stem allometry were found when comparing dgl to dbh, suggesting greater increase in dbh with height. The relationship between stability safety factor (SSF and palm height showed that both dgl and dbh were found to be above McMahon's theoretical buckling limit for dicotyledonous trees, but some individuals approached this limit in relation to dbh. Despite displaying a similar decreasing pattern of SSF with height, differences found in SSF along the stem - greater SSF for dgl when compared to dbh - indicate that the risk of mechanism failure in palms depends upon the size and varies along the stem. Distinct allometric relationships along the stem obtained for Euterpe edulis may be reflecting possible differences in stem design and growth strategies.Neste trabalho foram analisadas as relações entre o diâmetro e a altura de uma palmeira Neotropical (Euterpe edulis comum na Floresta Atlântica do SE do Brasil. As relações observadas entre a altura e o diâmetro ao longo do estipe (diâmetro ao nível do solo (DAS, e diâmetro ao nível do peito (DAP foram comparadas a três modelos teóricos de estabilidade mecânica: similaridade elástica, similaridade de estresse e similaridade geométrica. As inclinações das regressões altura-diâmetro não se ajustaram a nenhum dos modelos de estabilidade mecânica. Diferenças significativas na alometria do estipe foram encontradas comparando-se as rela

Electron–hole two-stream instability in a quantum semiconductor plasma with exchange-correlation effects

International Nuclear Information System (INIS)

Zeba, I.; Yahia, M.E.; Shukla, P.K.; Moslem, W.M.

2012-01-01

The electron–hole two-stream instability in a quantum semiconductor plasma has been studied including electrons and holes quantum recoil effects, exchange-correlation potentials, and degenerate pressures of the plasma species. Typical values of GaAs and GaSb semiconductors are used to estimate the growth rate of the two-stream instability. The effects of electron– and hole–phonon collision, quantum recoil effects, the streaming velocities, and the corresponding threshold on the growth rate are investigated numerically. Considering the phonon susceptibility allows the acoustic mode to exist and the collisional instability arises in combination with drift of the holes. -- Highlights: ► Electron–hole two stream instability in quantum plasmas is presented. ► Typical values of GaAs and GaSb semiconductors are used to estimate the growth rate. ► The streaming velocities and the corresponding threshold on the growth rate are investigated numerically.

An illustrated key to Neotropical species of the genus Meteorus Haliday (Hymenoptera, Braconidae, Euphorinae).

Science.gov (United States)

Aguirre, Helmuth; de Almeida, Luis Felipe; Shaw, Scott Richard; Sarmiento, Carlos E

2015-01-01

A comprehensive key for 75 species of Meteorus distributed across 15 Neotropical countries is presented. Eleven new species from Bolivia, Costa Rica and Ecuador are described: Meteorusalbistigma, Meteoruscarolae, Meteoruseurysaccavorus, Meteorusfallacavus, Meteorusflavistigma, Meteorushaimowitzi, Meteorusmagnoculus, Meteorusmartinezi, Meteorusmicrocavus, Meteorusnoctuivorus and Meteorusorion. Expanded range distributions are recorded for Meteorusandreae, Meteorusfarallonensis, Meteorusguineverae, Meteorusjerodi, Meteoruskraussi, Meteoruspapiliovorus and Meteorusquimbayensis. The host of Meteorusjerodi is reported for the first time: a noctuid larva feeding on Asteraceae. Meteoruspapiliovorus is recorded attacking Papilionidae larvae in Ecuador, therefore displaying a similar host family preference as formerly documented from Costa Rica and Colombia.

Review of the Neotropical scale insects formerly assigned to Coelostomidiidae and here transferred to a new tribe within the Monophlebidae (Hemiptera: Sternorrhyncha: Coccoidea).

Science.gov (United States)

Foldi, I; Gullan, P J

2014-12-24

This study reviews the status of all Neotropical genera and species of Coelostomidiidae (Hemiptera: Coccoidea) and transfers them to the family Monophlebidae in the Cryptokermesini Foldi & Gullan tribe n. (the tribe Cryptokermini Tao & Hao is recognised here as a nomen nudum). This change of family placement for Neotropical taxa is based on the morphology of adult males, as supported by the phylogenetic study of Hodgson & Hardy (2013), and by unpublished DNA data. New diagnoses are provided for each of the four recognised genera of Cryptokermesini: Cryptokermes Hempel, Mimosicerya Cockerell, Neocoelostoma Hempel and Paracoelostoma Morrison. The genus Nautococcus Vayssière is considered here to be a junior synonym (syn. n.) of Mimosicerya and the type species of Nautococcus, N. schraderae Vayssière, thus becomes M. schraderae (Vayssière) comb. n. Cryptokermes mexicanus Morrison is transferred to Mimosicerya as M. mexicana (Morrison) comb. n. Also Cryptokermes mimosae Foldi does not fit the morphological concept of Cryptokermes and is excluded from this genus and revision, and from the new tribe; its taxonomic position is uncertain and requires further study. All type species of the Cryptokermesini, including N. schraderae (as M. schraderae), are redescribed and illustrated based on most female instars and available adult males, examined using optical and scanning electron microscopes. Adult males are described and illustrated only for M. schraderae and N. xerophila. Keys are provided to distinguish the Neotropical monophlebid tribes Cryptokermesini and Llaveiini and to recognise each cryptokermesine genus based on female instars and first-instar nymphs. The included species of Cryptokermesini and their known distributions are: Cryptokermes brasiliensis Hempel from Brazil and C. oaxaensis Foldi from Mexico; Mimosicerya hempeli (Cockerell) from Brazil, M. mexicana from Mexico, M. schraderae from Panama and M. williamsi Foldi from Venezuela; Neocoelostoma xerophila

StreamCat

Data.gov (United States)

U.S. Environmental Protection Agency — The StreamCat Dataset provides summaries of natural and anthropogenic landscape features for ~2.65 million streams, and their associated catchments, within the...

Stream Crossings

Data.gov (United States)

Vermont Center for Geographic Information — Physical measurements and attributes of stream crossing structures and adjacent stream reaches which are used to provide a relative rating of aquatic organism...

A new species of Aplectana (Nematoda: Cosmocercidae) parasite of Pleurodema nebulosum (Anura: Leptodactylidae) from the Monte desert, Argentina, with a key to Neotropical species of the genus Aplectana.

Science.gov (United States)

Gomez, Mauricio D Piñeiro; González, Cynthya E; Sanabria, Eduardo A

2017-03-27

Here we describe a new cosmocercid nematode, Aplectana nebulosa sp. nov., from the small and large intestines of Pleurodema nebulosum (Anura: Leptodactylidae), from the Monte desert of San Juan, Argentina. The new species belongs to the Aplectana group that possesses a gubernaculum and unpaired adcloacal papilla anteriorly to cloaca. It resembles A. membranosa, A. paraelenae and A. travassosi by the presence of four adcloacal papillae, but differs from those species by the following characters: number and arrangement of precloacal papillae; number and arrangement of postcloacal papillae; shape and size of spicules and gubernaculum, and by the presence of lateral alae in caudal region of males. The description of the new species is based on light microscopy and scanning electron microscopy (SEM) and we also provide a key to Neotropical species of Aplectana.

Prioritized Contact Transport Stream

Science.gov (United States)

Hunt, Walter Lee, Jr. (Inventor)

2015-01-01

A detection process, contact recognition process, classification process, and identification process are applied to raw sensor data to produce an identified contact record set containing one or more identified contact records. A prioritization process is applied to the identified contact record set to assign a contact priority to each contact record in the identified contact record set. Data are removed from the contact records in the identified contact record set based on the contact priorities assigned to those contact records. A first contact stream is produced from the resulting contact records. The first contact stream is streamed in a contact transport stream. The contact transport stream may include and stream additional contact streams. The contact transport stream may be varied dynamically over time based on parameters such as available bandwidth, contact priority, presence/absence of contacts, system state, and configuration parameters.

Re-Meandering of Lowland Streams

DEFF Research Database (Denmark)

Pedersen, Morten Lauge; Kristensen, Klaus Kevin; Friberg, Nikolai

2014-01-01

We evaluated the restoration of physical habitats and its influence on macroinvertebrate community structure in 18 Danish lowland streams comprising six restored streams, six streams with little physical alteration and six channelized streams. We hypothesized that physical habitats...... and macroinvertebrate communities of restored streams would resemble those of natural streams, while those of the channelized streams would differ from both restored and near-natural streams. Physical habitats were surveyed for substrate composition, depth, width and current velocity. Macroinvertebrates were sampled...... along 100 m reaches in each stream, in edge habitats and in riffle/run habitats located in the center of the stream. Restoration significantly altered the physical conditions and affected the interactions between stream habitat heterogeneity and macroinvertebrate diversity. The substrate in the restored...

StreamExplorer: A Multi-Stage System for Visually Exploring Events in Social Streams.

Science.gov (United States)

Wu, Yingcai; Chen, Zhutian; Sun, Guodao; Xie, Xiao; Cao, Nan; Liu, Shixia; Cui, Weiwei

2017-10-18

Analyzing social streams is important for many applications, such as crisis management. However, the considerable diversity, increasing volume, and high dynamics of social streams of large events continue to be significant challenges that must be overcome to ensure effective exploration. We propose a novel framework by which to handle complex social streams on a budget PC. This framework features two components: 1) an online method to detect important time periods (i.e., subevents), and 2) a tailored GPU-assisted Self-Organizing Map (SOM) method, which clusters the tweets of subevents stably and efficiently. Based on the framework, we present StreamExplorer to facilitate the visual analysis, tracking, and comparison of a social stream at three levels. At a macroscopic level, StreamExplorer uses a new glyph-based timeline visualization, which presents a quick multi-faceted overview of the ebb and flow of a social stream. At a mesoscopic level, a map visualization is employed to visually summarize the social stream from either a topical or geographical aspect. At a microscopic level, users can employ interactive lenses to visually examine and explore the social stream from different perspectives. Two case studies and a task-based evaluation are used to demonstrate the effectiveness and usefulness of StreamExplorer.Analyzing social streams is important for many applications, such as crisis management. However, the considerable diversity, increasing volume, and high dynamics of social streams of large events continue to be significant challenges that must be overcome to ensure effective exploration. We propose a novel framework by which to handle complex social streams on a budget PC. This framework features two components: 1) an online method to detect important time periods (i.e., subevents), and 2) a tailored GPU-assisted Self-Organizing Map (SOM) method, which clusters the tweets of subevents stably and efficiently. Based on the framework, we present Stream

Some Possible Cases of Escape Mimicry in Neotropical Butterflies.

Science.gov (United States)

Pinheiro, C E G; Freitas, A V L

2014-10-01

The possibility that escape or evasive mimicry evolved in butterflies and other prey insects in a similar fashion to classical Batesian and Müllerian mimicry has long been advanced in the literature. However, there is a general disagreement among lepidopterists and evolutionary biologists on whether or not escape mimicry exists, as well as in which mimicry rings this form of mimicry has evolved. Here, we review some purported cases of escape mimicry in Neotropical butterflies and suggest new mimicry rings involving several species of Archaeoprepona, Prepona, and Doxocopa (the "bright blue bands" ring) and species of Colobura and Hypna (the "creamy bands" ring) where the palatability of butterflies, their ability to escape predator attacks, geographic distribution, relative abundance, and co-occurrence in the same habitats strongly suggest that escape mimicry is involved. In addition, we also indicate other butterfly taxa whose similarities of coloration patterns could be due to escape mimicry and would constitute important case studies for future investigation.

Phaonia Robineau-Desvoidy (Diptera, Muscidae, Phaoniinae: II: revisão das espécies Phaonia Robineau-Desvoidy (Diptera, Muscidae, Phaoniinae: II: revision of the neotropical species

Directory of Open Access Journals (Sweden)

Sônia Maria Prevedello Coelho

2000-09-01

Full Text Available Thirty eight species are recognized in the Neotropical Region. Twenty four are redescribed and illustrated and fourteen were not redescribed, because they are well definite in the original description. A new combination for Mydaea triseta Curran, 1931 to Phaonia and the revalidation of P. nigripuncta Stein, 1911 are made. Five new synonyms are proposed: P. coquilletii (Vimmer, 1939 = P. punctinervis Stein, 1911; P. nigrocincta Stein, 1918 = P. abdita (Giglio-Tos, 1893; P. praedatoria (Snyder, 1957 = P. latinervis (Stein, 1904; P. vulgata (Albuquerque & Medeiros, 1980 = P. similata (Albuquerque, 1957; P. nigra (Albuquerque & Medeiros, 1980 = P. trispila (Bigot, 1885. A key to the neotropical species is presented for the thirty eight recognized species.

Nutrition of Six Selected Neo-Tropical Mammals in Trinidad and Tobago with the Potential for Domestication.

Science.gov (United States)

Lall, Kavita Ranjeeta; Jones, Kegan Romelle; Garcia, Gary Wayne

2018-05-14

This review highlights the available literature on the nutrition of six neo-tropical animals with the potential for domestication-the agouti ( Dasyprocta leporina / D. aguti ), lappe ( Agouti paca ), capybara ( Hydrochoerus hydrochaeris ), manicou/opossum ( Didelphis marsupialis insularis ), collared peccary ( Peccary tajucu ) and the red brokcet deer ( Mazama americana ). Over 100 references were used, spanning over 100 years. The earliest being 1915 and the most recent being 2018. The references used in this review were synthesized to give a detailed look of the dentition, anatomy of the gastrointestinal tract and type of feed these animals consume. Nutritional requirements of the animals are required to understand what is needed for growth, maintenance and reproduction of each physiological stage. The agouti ( D. leporina/D. aguti ) was observed to be a monogastric mammal that fed primarily on fruits, seeds, animal matter and practiced caecotrophy. The lappe/paca ( C. paca/A. paca ) was described as a strict herbivore and a frugivore which practiced caecotrophy, with a diet that varied throughout the year, according to food availability. The capybara ( H. hydrochaeris ) was found to be the largest known rodent and was described as a semiaquatic hindgut fermenter that practiced caecotrophy. The manicou/opossum ( D. marsupialis insularis ) was found to be an omnivore with a simple stomach. The collared peccary ( T. tajacu ) was found to be frugivorous. Their unique stomach enabled them to consume a wide variety of feedstuff, allowing them to be found in a wide range of habitats. The red brocket deer ( M. americana ), a ruminant, was described as a browser that consumed mainly fruits and seeds and they frequented mineral lick. Knowledge of what they consume in the wild is important, so that we know what to feed in captivity. There is also the need to evaluate captive diets while trying to domesticate these mammals and develop nutrient requirement tables for these

Pilot-Streaming: Design Considerations for a Stream Processing Framework for High-Performance Computing

OpenAIRE

Andre Luckow; Peter Kasson; Shantenu Jha

2016-01-01

This White Paper (submitted to STREAM 2016) identifies an approach to integrate streaming data with HPC resources. The paper outlines the design of Pilot-Streaming, which extends the concept of Pilot-abstraction to streaming real-time data.

Introduction to stream: An Extensible Framework for Data Stream Clustering Research with R

Directory of Open Access Journals (Sweden)

Michael Hahsler

2017-02-01

Full Text Available In recent years, data streams have become an increasingly important area of research for the computer science, database and statistics communities. Data streams are ordered and potentially unbounded sequences of data points created by a typically non-stationary data generating process. Common data mining tasks associated with data streams include clustering, classification and frequent pattern mining. New algorithms for these types of data are proposed regularly and it is important to evaluate them thoroughly under standardized conditions. In this paper we introduce stream, a research tool that includes modeling and simulating data streams as well as an extensible framework for implementing, interfacing and experimenting with algorithms for various data stream mining tasks. The main advantage of stream is that it seamlessly integrates with the large existing infrastructure provided by R. In addition to data handling, plotting and easy scripting capabilities, R also provides many existing algorithms and enables users to interface code written in many programming languages popular among data mining researchers (e.g., C/C++, Java and Python. In this paper we describe the architecture of stream and focus on its use for data stream clustering research. stream was implemented with extensibility in mind and will be extended in the future to cover additional data stream mining tasks like classification and frequent pattern mining.

Benthic invertebrate fauna, small streams

Science.gov (United States)

J. Bruce Wallace; S.L. Eggert

2009-01-01

Small streams (first- through third-order streams) make up >98% of the total number of stream segments and >86% of stream length in many drainage networks. Small streams occur over a wide array of climates, geology, and biomes, which influence temperature, hydrologic regimes, water chemistry, light, substrate, stream permanence, a basin's terrestrial plant...

Phylogenetic relationships of the cultivated neotropical palm Bactris gasipaes (arecaceae) with its wild relatives inferred from chloroplast and nuclear DNA polymorphisms

NARCIS (Netherlands)

Couvreur, T.L.P.; Hahn, K.; Granville, de J.J.; Pham, J.L.; Ludena, B.; Pintaud, J.C.

2007-01-01

Peach palm (Bactris gasipaes Kunth.) is the only Neotropical palm domesticated since pre-Columbian times. It plays an important role not only at the local level due to its very nutritious fruits, but also in the international market for its gourmet palm heart. Phylogenetic relationships of the peach

The genera Cosmopterix Hübner and Pebobs Hodges in the New World with special attention to the Neotropical fauna (Lepidoptera: Cosmopterigidae)

NARCIS (Netherlands)

Koster, J.C.

2010-01-01

The genera Cosmopterix Hübner, [1825] and Pebobs Hodges, 1978 (Cosmopterigidae) of the New World are revised, for the Neotropical fauna for the first time. A total of 102 species is recognized and 49 species are described as new: Cosmopterix adrastea spec. nov., C. amalthea spec. nov., C. ananke

Inventory of miscellaneous streams

International Nuclear Information System (INIS)

Lueck, K.J.

1995-09-01

On December 23, 1991, the US Department of Energy, Richland Operations Office (RL) and the Washington State Department of Ecology (Ecology) agreed to adhere to the provisions of the Department of Ecology Consent Order. The Consent Order lists the regulatory milestones for liquid effluent streams at the Hanford Site to comply with the permitting requirements of Washington Administrative Code. The RL provided the US Congress a Plan and Schedule to discontinue disposal of contaminated liquid effluent into the soil column on the Hanford Site. The plan and schedule document contained a strategy for the implementation of alternative treatment and disposal systems. This strategy included prioritizing the streams into two phases. The Phase 1 streams were considered to be higher priority than the Phase 2 streams. The actions recommended for the Phase 1 and 2 streams in the two reports were incorporated in the Hanford Federal Facility Agreement and Consent Order. Miscellaneous Streams are those liquid effluents streams identified within the Consent Order that are discharged to the ground but are not categorized as Phase 1 or Phase 2 Streams. This document consists of an inventory of the liquid effluent streams being discharged into the Hanford soil column

Morphology and Efficiency of a Specialized Foraging Behavior, Sediment Sifting, in Neotropical Cichlid Fishes

Science.gov (United States)

Willis, Stuart; Watkins, Crystal; Honeycutt, Rodney L.; Winemiller, Kirk O.

2014-01-01

Understanding of relationships between morphology and ecological performance can help to reveal how natural selection drives biological diversification. We investigate relationships between feeding behavior, foraging performance and morphology within a diverse group of teleost fishes, and examine the extent to which associations can be explained by evolutionary relatedness. Morphological adaptation associated with sediment sifting was examined using a phylogenetic linear discriminant analysis on a set of ecomorphological traits from 27 species of Neotropical cichlids. For most sifting taxa, feeding behavior could be effectively predicted by a linear discriminant function of ecomorphology across multiple clades of sediment sifters, and this pattern could not be explained by shared evolutionary history alone. Additionally, we tested foraging efficiency in seven Neotropical cichlid species, five of which are specialized benthic feeders with differing head morphology. Efficiency was evaluated based on the degree to which invertebrate prey could be retrieved at different depths of sediment. Feeding performance was compared both with respect to feeding mode and species using a phylogenetic ANCOVA, with substrate depth as a covariate. Benthic foraging performance was constant across sediment depths in non-sifters but declined with depth in sifters. The non-sifting Hypsophrys used sweeping motions of the body and fins to excavate large pits to uncover prey; this tactic was more efficient for consuming deeply buried invertebrates than observed among sediment sifters. Findings indicate that similar feeding performance among sediment-sifting cichlids extracting invertebrate prey from shallow sediment layers reflects constraints associated with functional morphology and, to a lesser extent, phylogeny. PMID:24603485

Morphology and efficiency of a specialized foraging behavior, sediment sifting, in neotropical cichlid fishes.

Directory of Open Access Journals (Sweden)

Hernán López-Fernández

Full Text Available Understanding of relationships between morphology and ecological performance can help to reveal how natural selection drives biological diversification. We investigate relationships between feeding behavior, foraging performance and morphology within a diverse group of teleost fishes, and examine the extent to which associations can be explained by evolutionary relatedness. Morphological adaptation associated with sediment sifting was examined using a phylogenetic linear discriminant analysis on a set of ecomorphological traits from 27 species of Neotropical cichlids. For most sifting taxa, feeding behavior could be effectively predicted by a linear discriminant function of ecomorphology across multiple clades of sediment sifters, and this pattern could not be explained by shared evolutionary history alone. Additionally, we tested foraging efficiency in seven Neotropical cichlid species, five of which are specialized benthic feeders with differing head morphology. Efficiency was evaluated based on the degree to which invertebrate prey could be retrieved at different depths of sediment. Feeding performance was compared both with respect to feeding mode and species using a phylogenetic ANCOVA, with substrate depth as a covariate. Benthic foraging performance was constant across sediment depths in non-sifters but declined with depth in sifters. The non-sifting Hypsophrys used sweeping motions of the body and fins to excavate large pits to uncover prey; this tactic was more efficient for consuming deeply buried invertebrates than observed among sediment sifters. Findings indicate that similar feeding performance among sediment-sifting cichlids extracting invertebrate prey from shallow sediment layers reflects constraints associated with functional morphology and, to a lesser extent, phylogeny.

Morphology and efficiency of a specialized foraging behavior, sediment sifting, in neotropical cichlid fishes.

Science.gov (United States)

López-Fernández, Hernán; Arbour, Jessica; Willis, Stuart; Watkins, Crystal; Honeycutt, Rodney L; Winemiller, Kirk O

2014-01-01

Understanding of relationships between morphology and ecological performance can help to reveal how natural selection drives biological diversification. We investigate relationships between feeding behavior, foraging performance and morphology within a diverse group of teleost fishes, and examine the extent to which associations can be explained by evolutionary relatedness. Morphological adaptation associated with sediment sifting was examined using a phylogenetic linear discriminant analysis on a set of ecomorphological traits from 27 species of Neotropical cichlids. For most sifting taxa, feeding behavior could be effectively predicted by a linear discriminant function of ecomorphology across multiple clades of sediment sifters, and this pattern could not be explained by shared evolutionary history alone. Additionally, we tested foraging efficiency in seven Neotropical cichlid species, five of which are specialized benthic feeders with differing head morphology. Efficiency was evaluated based on the degree to which invertebrate prey could be retrieved at different depths of sediment. Feeding performance was compared both with respect to feeding mode and species using a phylogenetic ANCOVA, with substrate depth as a covariate. Benthic foraging performance was constant across sediment depths in non-sifters but declined with depth in sifters. The non-sifting Hypsophrys used sweeping motions of the body and fins to excavate large pits to uncover prey; this tactic was more efficient for consuming deeply buried invertebrates than observed among sediment sifters. Findings indicate that similar feeding performance among sediment-sifting cichlids extracting invertebrate prey from shallow sediment layers reflects constraints associated with functional morphology and, to a lesser extent, phylogeny.

Toward reliable estimates of seed removal by small mammals and birds in the Neotropics

Directory of Open Access Journals (Sweden)

AV. Christianini

Full Text Available Birds are often considered seed predators of less importance when compared to rodents or granivorous ants in studies of seed predation using selective exclosures. However, it is possible that the role of granivorous birds interacting with seeds on the floor of Neotropical forests is being underestimated, if the selective exclosures designed to allow exclusive access to small rodents do not work properly in the Neotropics. We used an experimental approach to evaluate whether birds could remove seeds from selective exclosures designed to allow exclusive access to rodents. We compared seed removal from two paired treatments in the field: an open treatment (control allowing the access to all vertebrates, and a selective exclosure treatment, where seeds were placed under a cage staked to the ground and covered on top and on the laterals by wire mesh of varying sizes. Treatments were placed in the center of a sand quadrat in order to record the visit of vertebrates from their footprints. Although the selective exclosures are used to tell apart the small mammal seed removal from that of other animals, birds could persistently remove seeds from selective exclosures. Thus, the role of birds interacting with seeds on the floor of tropical forests may be underestimated for some plant species, due to an artifact of the exclosure method employed. Exclosures of 40 x 40 x 40 cm should be efficient to deter the removal of seeds by birds, allowing the consumption of the seeds by small mammals at the same time.

Streaming Jeans-Alfvén Instability in Quantum Magnetoplasmas

Science.gov (United States)

Jamil, M.; Rasheed, A.; Hadi, F.; Ali, G.; Ayub, M.

2017-10-01

The physical mechanism of magnetosonic perturbations which modifies the Jeans instability in streaming quantum dusty magnetoplasmas is examined. These perturbations are low frequency and electromagnetic in nature that propagate with Alfvén speed. The fluid model consisting of momentum balance equations for quantum plasmas, Poisson's equation for gravitational potential, and Maxwell's equations for magnetosonic perturbations is used for the coupled solution. The numerical analysis of the dispersion relation elaborates the significant contribution of streaming speed of plasma species at equilibrium v0, uniform external magnetic field B0, electron number density at equilibrium n0e, and variable dust mass md over the Jeans instability. This study helps to understand the possible mechanism responsible for the formation of astrophysical objects.

Trypanosoma cruzi infection in neotropical wild carnivores (Mammalia: Carnivora: at the top of the T. cruzi transmission chain.

Directory of Open Access Journals (Sweden)

Fabiana Lopes Rocha

Full Text Available Little is known on the role played by Neotropical wild carnivores in the Trypanosoma cruzi transmission cycles. We investigated T. cruzi infection in wild carnivores from three sites in Brazil through parasitological and serological tests. The seven carnivore species examined were infected by T. cruzi, but high parasitemias detectable by hemoculture were found only in two Procyonidae species. Genotyping by Mini-exon gene, PCR-RFLP (1f8/Akw21I and kDNA genomic targets revealed that the raccoon (Procyon cancrivorus harbored TcI and the coatis (Nasua nasua harbored TcI, TcII, TcIII-IV and Trypanosoma rangeli, in single and mixed infections, besides four T. cruzi isolates that displayed odd band patterns in the Mini-exon assay. These findings corroborate the coati can be a bioaccumulator of T. cruzi Discrete Typing Units (DTU and may act as a transmission hub, a connection point joining sylvatic transmission cycles within terrestrial and arboreal mammals and vectors. Also, the odd band patterns observed in coatis' isolates reinforce that T. cruzi diversity might be much higher than currently acknowledged. Additionally, we assembled our data with T. cruzi infection on Neotropical carnivores' literature records to provide a comprehensive analysis of the infection patterns among distinct carnivore species, especially considering their ecological traits and phylogeny. Altogether, fifteen Neotropical carnivore species were found naturally infected by T. cruzi. Species diet was associated with T. cruzi infection rates, supporting the hypothesis that predator-prey links are important mechanisms for T. cruzi maintenance and dispersion in the wild. Distinct T. cruzi infection patterns across carnivore species and study sites were notable. Musteloidea species consistently exhibit high parasitemias in different studies which indicate their high infectivity potential. Mesocarnivores that feed on both invertebrates and mammals, including the coati, a host that

Time-Based Data Streams: Fundamental Concepts for a Data Resource for Streams

Energy Technology Data Exchange (ETDEWEB)

Beth A. Plale

2009-10-10

Real time data, which we call data streams, are readings from instruments, environmental, bodily or building sensors that are generated at regular intervals and often, due to their volume, need to be processed in real time. Often a single pass is all that can be made on the data, and a decision to discard or keep the instance is made on the spot. Too, the stream is for all practical purposes indefinite, so decisions must be made on incomplete knowledge. This notion of data streams has a different set of issues from a file, for instance, that is byte streamed to a reader. The file is finite, so the byte stream is becomes a processing convenience more than a fundamentally different kind of data. Through the duration of the project we examined three aspects of streaming data: the first, techniques to handle streaming data in a distributed system organized as a collection of web services, the second, the notion of the dashboard and real time controllable analysis constructs in the context of the Fermi Tevatron Beam Position Monitor, and third and finally, we examined provenance collection of stream processing such as might occur as raw observational data flows from the source and undergoes correction, cleaning, and quality control. The impact of this work is severalfold. We were one of the first to advocate that streams had little value unless aggregated, and that notion is now gaining general acceptance. We were one of the first groups to grapple with the notion of provenance of stream data also.

Asteroid/meteorite streams

Science.gov (United States)

Drummond, J.

The independent discovery of the same three streams (named alpha, beta, and gamma) among 139 Earth approaching asteroids and among 89 meteorite producing fireballs presents the possibility of matching specific meteorites to specific asteroids, or at least to asteroids in the same stream and, therefore, presumably of the same composition. Although perhaps of limited practical value, the three meteorites with known orbits are all ordinary chondrites. To identify, in general, the taxonomic type of the parent asteroid, however, would be of great scientific interest since these most abundant meteorite types cannot be unambiguously spectrally matched to an asteroid type. The H5 Pribram meteorite and asteroid 4486 (unclassified) are not part of a stream, but travel in fairly similar orbits. The LL5 Innisfree meteorite is orbitally similar to asteroid 1989DA (unclassified), and both are members of a fourth stream (delta) defined by five meteorite-dropping fireballs and this one asteroid. The H5 Lost City meteorite is orbitally similar to 1980AA (S type), which is a member of stream gamma defined by four asteroids and four fireballs. Another asteroid in this stream is classified as an S type, another is QU, and the fourth is unclassified. This stream suggests that ordinary chondrites should be associated with S (and/or Q) asteroids. Two of the known four V type asteroids belong to another stream, beta, defined by five asteroids and four meteorite-dropping (but unrecovered) fireballs, making it the most probable source of the eucrites. The final stream, alpha, defined by five asteroids and three fireballs is of unknown composition since no meteorites have been recovered and only one asteroid has an ambiguous classification of QRS. If this stream, or any other as yet undiscovered ones, were found to be composed of a more practical material (e.g., water or metalrich), then recovery of the associated meteorites would provide an opportunity for in-hand analysis of a potential

Diversification of the silverspot butterflies (Nymphalidae) in the Neotropics inferred from multi-locus DNA sequences.

Science.gov (United States)

Massardo, Darli; Fornel, Rodrigo; Kronforst, Marcus; Gonçalves, Gislene Lopes; Moreira, Gilson Rudinei Pires

2015-01-01

The tribe Heliconiini (Lepidoptera: Nymphalidae) is a diverse group of butterflies distributed throughout the Neotropics, which has been studied extensively, in particular the genus Heliconius. However, most of the other lineages, such as Dione, which are less diverse and considered basal within the group, have received little attention. Basic information, such as species limits and geographical distributions remain uncertain for this genus. Here we used multilocus DNA sequence data and the geographical distribution analysis across the entire range of Dione in the Neotropical region in order to make inferences on the evolutionary history of this poorly explored lineage. Bayesian time-tree reconstruction allows inferring two major diversification events in this tribe around 25mya. Lineages thought to be ancient, such as Dione and Agraulis, are as recent as Heliconius. Dione formed a monophyletic clade, sister to the genus Agraulis. Dione juno, D. glycera and D. moneta were reciprocally monophyletic and formed genetic clusters, with the first two more close related than each other in relation to the third. Divergence time estimates support the hypothesis that speciation in Dione coincided with both the rise of Passifloraceae (the host plants) and the uplift of the Andes. Since the sister species D. glycera and D. moneta are specialized feeders on passion-vine lineages that are endemic to areas located either within or adjacent to the Andes, we inferred that they co-speciated with their host plants during this vicariant event. Copyright © 2014 Elsevier Inc. All rights reserved.

Neotropical dry forest wildlife water hole use and management

Directory of Open Access Journals (Sweden)

Christopher Vaughan

1999-12-01

Full Text Available Selected wildlife species diurnal use of a natural water hole (QD and an artificial water hole (AW were studied during 1990 dry season at Guanacaste Conservation Area, Costa Rica. In total, 919 individuals (six mammal and one game bird species consumed water from QD, while 713 individuals (four mammal species consumed water from AW. Estimated daily water consumption by selected wildlife species was 29.7 l at QD and 27.3 l at AW. Estimated 24-h water consumed by all wildlife species or evaporated was 44.6 l at QD and 41.1 l at AW. This resulted from summing: a water consumed by studied species, b estimated 24-hour water consumed by other wildlife (QD = 14.85 l, AW = 13.65 l and c daily water evaporation (QD = 0.04 l, AW = 0.10 l. During a 120-day dry season, AW required about 4 932 l of water from the park administration. Management implications for neotropical dry forest water holes are discussed.Se estudió el uso diurno de un ojo de agua natural (QD y otro artificial (AW a finales de la época seca de 1990 en el Area de Conservacion de Guanacaste, Costa Rica. En total 919 individuos (seis especies de mamíferos y una de ave cinegética consumieron agua de QD y 713 individuos (cuatro especies de mamíferos de AQ. Se estimó que en un dia, las especies de vida silvestre estudiados tomaron 29.7 l y 27.3 l de agua de QD y AW, respectivamente. El total de agua consumido o evaporado de cada ojo de agua durante 24-horas fue estimado en 44.6 l en QD y 41.1 l en AW, con base en: a agua bebida durante 12 h por las especies seleccionadas, b agua bebida por todos los otros individuos durante 24 h (QD = 14.85 l, AW = 13.65 l y c evaporación diaria (QD = 0.04 l, AW = 0.01 l. Para abastecer AW durante una epoca seca de 120 días, la administración del parque debe proveer 4 932 l de agua. Se discute las implicaciones de manejo en las regiones de bosque seco neotropical.

Spatial and temporal variation in soil CO2 efflux in an old-growth neotropical rain forest, LA Selva, Costa Rica

Science.gov (United States)

Luitgard Schwendenmann; Edzo Veldkamp; Tania Brenes; Joseph J. O' Brien; Jens Mackensen

2003-01-01

Our objectives were to quantify and compare soil CO2, efflux of two doininant soil types in an old-growth neotropical rain forest in the Atlantic zone of Costa Rica, and to evaluate the control of environmental Factors on CO2, release. We measured soil CO2 efflux from eight permanent soil chamhers on...

Phylogeny of Neotropical Cercosaura (Squamata: Gymnophthalmidae) lizards.

Science.gov (United States)

Torres-Carvajal, Omar; Lobos, Simón E; Venegas, Pablo J

2015-12-01

Among Neotropical lizards, the geographically widespread gymnophthalmid Cercosaura as currently defined includes lowland and highland taxa from Panama to Argentina, with some species occurring in the northern Andes. In this study we analyze three mitochondrial (12S, 16S, ND4) and one nuclear (c-mos) gene using Bayesian methods to clarify the phylogenetic relationships among most species of Cercosaura based on a well-supported phylogenetic hypothesis that also includes a large sample of other taxa within Cercosaurini. The phylogenetic tree obtained in this paper shows that Cercosaura as currently defined is not monophyletic. Two species from the northern Andes (C. dicra and C. vertebralis) are nested within Pholidobolus, which has been formerly recognized as a major radiation along the Andes of Ecuador and Colombia. Therefore, Cercosaura has probably not diversified in the northern Andes, although the phylogenetic position of C. hypnoides from the Andes of Colombia remains unknown. Tree topology and genetic distances support both recognition of C. ocellata bassleri as a distinct species, C. bassleri, and recognition of C. argula and C. oshaughnessyi as two different species. In the interest of promoting clarity and precision regarding the names of clades of gymnophthalmid lizards, we propose a phylogenetic definition of Cercosaura. Copyright © 2015 Elsevier Inc. All rights reserved.

Revisão do gênero neotropical Amazunculus Rafael (Diptera: Pipunculidae com descrição de três novas espécies e chave de identificação Revision of the Neotropical genus Amazunculus Rafael (Diptera: Pipunculidae with description of three new species and identification key

Directory of Open Access Journals (Sweden)

Joana Galinkin

2008-01-01

Full Text Available O gênero Amazunculus é exclusivo da região Neotropical, com a maioria dos seus registros no bioma amazônico. São pipunculídeos grandes, facilmente identificados pelos tarsos posteriores achatados e a veia alar dm-cu curva. Aqui são descritas as espécies Amazunculus cordigaster sp. nov., A. deargentatus sp. nov. e A. duckei sp. nov., cujas diagnoses são baseadas principalmente em características da genitália masculina. É apresentada uma chave para identificação das seis espécies do gênero.Amazunculus is an exclusively Neotropical genus which occurs mostly in the Amazon biome. They are large bodied Pipunculidae, easily identified by their flattened hind tarsus and curved dm-cu wing vein. Described here are Amazunculus cordigaster n. sp., A. deargentatus n. sp. and A. duckei n. sp., whose diagnoses are based mostly on male genitalia characteristics. An identification key to the six species of Amazunculus is provided.

Aeroacoustics of Three-Stream Jets

Science.gov (United States)

Henderson, Brenda S.

2012-01-01

Results from acoustic measurements of noise radiated from a heated, three-stream, co-annular exhaust system operated at subsonic conditions are presented. The experiments were conducted for a range of core, bypass, and tertiary stream temperatures and pressures. The nozzle system had a fan-to-core area ratio of 2.92 and a tertiary-to-core area ratio of 0.96. The impact of introducing a third stream on the radiated noise for third-stream velocities below that of the bypass stream was to reduce high frequency noise levels at broadside and peak jet-noise angles. Mid-frequency noise radiation at aft observation angles was impacted by the conditions of the third stream. The core velocity had the greatest impact on peak noise levels and the bypass-to-core mass flow ratio had a slight impact on levels in the peak jet-noise direction. The third-stream jet conditions had no impact on peak noise levels. Introduction of a third jet stream in the presence of a simulated forward-flight stream limits the impact of the third stream on radiated noise. For equivalent ideal thrust conditions, two-stream and three-stream jets can produce similar acoustic spectra although high-frequency noise levels tend to be lower for the three-stream jet.

Academic Self-Concepts in Ability Streams: Considering Domain Specificity and Same-Stream Peers

Science.gov (United States)

Liem, Gregory Arief D.; McInerney, Dennis M.; Yeung, Alexander S.

2015-01-01

The study examined the relations between academic achievement and self-concepts in a sample of 1,067 seventh-grade students from 3 core ability streams in Singapore secondary education. Although between-stream differences in achievement were large, between-stream differences in academic self-concepts were negligible. Within each stream, levels of…

Stream systems.

Science.gov (United States)

Jack E. Williams; Gordon H. Reeves

2006-01-01

Restored, high-quality streams provide innumerable benefits to society. In the Pacific Northwest, high-quality stream habitat often is associated with an abundance of salmonid fishes such as chinook salmon (Oncorhynchus tshawytscha), coho salmon (O. kisutch), and steelhead (O. mykiss). Many other native...

A relativistic self-consistent model for studying enhancement of space charge limited emission due to counter-streaming ions

Science.gov (United States)

Lin, M. C.; Verboncoeur, J.

2016-10-01

A maximum electron current transmitted through a planar diode gap is limited by space charge of electrons dwelling across the gap region, the so called space charge limited (SCL) emission. By introducing a counter-streaming ion flow to neutralize the electron charge density, the SCL emission can be dramatically raised, so electron current transmission gets enhanced. In this work, we have developed a relativistic self-consistent model for studying the enhancement of maximum transmission by a counter-streaming ion current. The maximum enhancement is found when the ion effect is saturated, as shown analytically. The solutions in non-relativistic, intermediate, and ultra-relativistic regimes are obtained and verified with 1-D particle-in-cell simulations. This self-consistent model is general and can also serve as a comparison for verification of simulation codes, as well as extension to higher dimensions.

Impacts of an invasive snail (Tarebia granifera) on nutrient cycling in tropical streams: the role of riparian deforestation in Trinidad, West Indies.

Science.gov (United States)

Moslemi, Jennifer M; Snider, Sunny B; Macneill, Keeley; Gilliam, James F; Flecker, Alexander S

2012-01-01

Non-native species and habitat degradation are two major catalysts of environmental change and often occur simultaneously. In freshwater systems, degradation of adjacent terrestrial vegetation may facilitate introduced species by altering resource availability. Here we examine how the presence of intact riparian cover influences the impact of an invasive herbivorous snail, Tarebia granifera, on nitrogen (N) cycling in aquatic systems on the island of Trinidad. We quantified snail biomass, growth, and N excretion in locations where riparian vegetation was present or removed to determine how snail demographics and excretion were related to the condition of the riparian zone. In three Neotropical streams, we measured snail biomass and N excretion in open and closed canopy habitats to generate estimates of mass- and area-specific N excretion rates. Snail biomass was 2 to 8 times greater and areal N excretion rates ranged from 3 to 9 times greater in open canopy habitats. Snails foraging in open canopy habitat also had access to more abundant food resources and exhibited greater growth and mass-specific N excretion rates. Estimates of ecosystem N demand indicated that snail N excretion in fully closed, partially closed, and open canopy habitats supplied 2%, 11%, and 16% of integrated ecosystem N demand, respectively. We conclude that human-mediated riparian canopy loss can generate hotspots of snail biomass, growth, and N excretion along tropical stream networks, altering the impacts of an invasive snail on the biogeochemical cycling of N.

First record of the neotropical otter Lontra longicaudis annectens (Carnivora, Mustelidae in the estuary Boca Negra, Jalisco, Mexico: an approach to understanding its diet.

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Rodríguez-Uribe, M.C.

2015-01-01

Full Text Available The first record of the neotropical otter Lontra longicaudis annectens in the estuary Boca Negra, Jalisco, Mexico is presented. It includes relevant information about its diet and a photograph in its natural habitat is showed.

The first cytogenetic data on Strumigenys louisianae Roger, 1863 (Formicidae: Myrmicinae: Dacetini: the lowest chromosome number in the Hymenoptera of the neotropical region.

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Ana Paula Alves-Silva

Full Text Available In the present study, the first cytogenetic data was obtained for the ant species Strumigenys louisianae, from a genus possessing no previous cytogenetic data for the Neotropical region. The chromosome number observed was 2n = 4, all possessing metacentric morphology. Blocks rich in GC base pairs were observed in the interstitial region of the short arm of the largest chromosome pair, which may indicate that this region corresponds to the NORs. The referred species presented the lowest chromosome number observed for the subfamily Myrmicinae and for the Hymenoptera found in the Neotropical region. Observation of a low chromosome number karyotype has been described in Myrmecia croslandi, in which the occurrence of tandem fusions accounts for the most probable rearrangement for its formation. The accumulation of cytogenetic data may carry crucial information to ensure deeper understanding of the systematics of the tribe Dacetini.

Biomass resilience of Neotropical secondary forests.

Science.gov (United States)

Poorter, Lourens; Bongers, Frans; Aide, T Mitchell; Almeyda Zambrano, Angélica M; Balvanera, Patricia; Becknell, Justin M; Boukili, Vanessa; Brancalion, Pedro H S; Broadbent, Eben N; Chazdon, Robin L; Craven, Dylan; de Almeida-Cortez, Jarcilene S; Cabral, George A L; de Jong, Ben H J; Denslow, Julie S; Dent, Daisy H; DeWalt, Saara J; Dupuy, Juan M; Durán, Sandra M; Espírito-Santo, Mario M; Fandino, María C; César, Ricardo G; Hall, Jefferson S; Hernandez-Stefanoni, José Luis; Jakovac, Catarina C; Junqueira, André B; Kennard, Deborah; Letcher, Susan G; Licona, Juan-Carlos; Lohbeck, Madelon; Marín-Spiotta, Erika; Martínez-Ramos, Miguel; Massoca, Paulo; Meave, Jorge A; Mesquita, Rita; Mora, Francisco; Muñoz, Rodrigo; Muscarella, Robert; Nunes, Yule R F; Ochoa-Gaona, Susana; de Oliveira, Alexandre A; Orihuela-Belmonte, Edith; Peña-Claros, Marielos; Pérez-García, Eduardo A; Piotto, Daniel; Powers, Jennifer S; Rodríguez-Velázquez, Jorge; Romero-Pérez, I Eunice; Ruíz, Jorge; Saldarriaga, Juan G; Sanchez-Azofeifa, Arturo; Schwartz, Naomi B; Steininger, Marc K; Swenson, Nathan G; Toledo, Marisol; Uriarte, Maria; van Breugel, Michiel; van der Wal, Hans; Veloso, Maria D M; Vester, Hans F M; Vicentini, Alberto; Vieira, Ima C G; Bentos, Tony Vizcarra; Williamson, G Bruce; Rozendaal, Danaë M A

2016-02-11

Land-use change occurs nowhere more rapidly than in the tropics, where the imbalance between deforestation and forest regrowth has large consequences for the global carbon cycle. However, considerable uncertainty remains about the rate of biomass recovery in secondary forests, and how these rates are influenced by climate, landscape, and prior land use. Here we analyse aboveground biomass recovery during secondary succession in 45 forest sites and about 1,500 forest plots covering the major environmental gradients in the Neotropics. The studied secondary forests are highly productive and resilient. Aboveground biomass recovery after 20 years was on average 122 megagrams per hectare (Mg ha(-1)), corresponding to a net carbon uptake of 3.05 Mg C ha(-1) yr(-1), 11 times the uptake rate of old-growth forests. Aboveground biomass stocks took a median time of 66 years to recover to 90% of old-growth values. Aboveground biomass recovery after 20 years varied 11.3-fold (from 20 to 225 Mg ha(-1)) across sites, and this recovery increased with water availability (higher local rainfall and lower climatic water deficit). We present a biomass recovery map of Latin America, which illustrates geographical and climatic variation in carbon sequestration potential during forest regrowth. The map will support policies to minimize forest loss in areas where biomass resilience is naturally low (such as seasonally dry forest regions) and promote forest regeneration and restoration in humid tropical lowland areas with high biomass resilience.

Investigations of Pulsed Plasma Streams Generated by 'Prosvet' device Operated with Different Gases

International Nuclear Information System (INIS)

Byrka, O.V.; Bandura, A.N.; Chebotarev, V.V. and others

2006-01-01

The paper presents the investigations of plasma streams generated by pulsed plasma gun 'Prosvet' operated with different gases: krypton (m=84) and helium (m=4). Contour parameters of working gas spectral lines (full intensities and half-widths) are used for determination of spatial distributions of the electron density and temperature. Temporal distributions of the spectral lines intensities (both neutrals and ions of working gas), impurity spectral lines and continuum intensities are analyzed. Plasma stream velocity was estimated by time-of-flight method between two monochromators (MUM) connected with photo-multiplier. longitudinal distributions of the plasma pressure for different time moments and varied distances from the accelerator output have been used for investigation of the plasma stream dynamics and study the plasma compression in the focus region for different operational regimes of plasma accelerator. Experiments show that operation regime of the accelerator and plasma stream parameters strongly depend on the gas atomic mass

PROXY-BASED PATCHING STREAM TRANSMISSION STRATEGY IN MOBILE STREAMING MEDIA SYSTEM

Institute of Scientific and Technical Information of China (English)

Liao Jianxin; Lei Zhengxiong; Ma Xutao; Zhu Xiaomin

2006-01-01

A mobile transmission strategy, PMPatching (Proxy-based Mobile Patching) transmission strategy is proposed, it applies to the proxy-based mobile streaming media system in Wideband Code Division Multiple Access (WCDMA) network. Performance of the whole system can be improved by using patching stream to transmit anterior part of the suffix that had been played back, and by batching all the demands for the suffix arrived in prefix period and patching stream transmission threshold period. Experimental results show that this strategy can efficiently reduce average network transmission cost and number of channels consumed in central streaming media server.

Passeriformes: nest predators and prey in a Neotropical Savannah in Central Brazil

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Leonardo F. França

2009-12-01

Full Text Available The identification of predators of birds' nests, crucial to a better understanding of predator-prey interactions, remains poorly known. Here we provide evidence that birds, and especially passerines, may depredate birds' nests in the Cerrado (Neotropical Savannah of Central Brazil. Data was collected primarily in a Conservation Unit (Estação Ecológica de Águas Emendadas during the breeding season, between 2003 and 2007. We report and discuss details on 14 events of nest predation, 12 of which by passerines, mostly by curl-crested jays - Cyanocorax cristatellus (Temminck, 1823. The results of our study suggest that the role of birds as nest predators in the Cerrado has been underestimated and needs to be further investigated.

The phylogeny of Simulium (Chirostilbia (Diptera: Simuliidae and perspectives on the systematics of the genus in the Neotropical Region

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Leonardo Henrique Gil-Azevedo

2012-03-01

Full Text Available Recently, knowledge of Neotropical Simuliidae has been accumulating quickly. However, information about supra-specific relationships is scarce and diagnoses of Simulium subgenera are unsatisfactory. To investigate the relationships among Simulium (Chirostilbia species and test the subgenus monophyly, we performed a cladistic analysis. The ingroup included all species of this subgenus and the outgroup included representatives of the 17 species groups of Neotropical Simulium and three Holarctic species. The study was based on a data matrix with 31 terminal taxa and 45 morphological characteristics of adult, pupa and larva. The phylogenetic analysis under equal weights resulted in eight most-parsimonious trees (length = 178, consistency index = 34, retention index = 67. The monophyly of the S. (Chirostilbia was not supported in our analysis. The Simulium subpallidum species group was closer to Simulium (Psilopelmia and Simulium (Ectemnaspis than to the Simulium pertinax species group. Additionally, we describe the three-dimensional shape of the terminalia of male and female of Simulium (Chirostilbia for the first time and provide comments about the taxonomic problems involving some species of the subgenus: Simulium acarayense, Simulium papaveroi, S. pertinax, Simulium serranum, Simulium striginotum and S. subpallidum.

Population history, phylogeography, and conservation genetics of the last Neotropical mega-herbivore, the lowland tapir (Tapirus terrestris

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de Thoisy Benoit

2010-09-01

Full Text Available Abstract Background Understanding the forces that shaped Neotropical diversity is central issue to explain tropical biodiversity and inform conservation action; yet few studies have examined large, widespread species. Lowland tapir (Tapirus terrrestris, Perissodactyla, Tapiridae is the largest Neotropical herbivore whose ancestors arrived in South America during the Great American Biotic Interchange. A Pleistocene diversification is inferred for the genus Tapirus from the fossil record, but only two species survived the Pleistocene megafauna extinction. Here, we investigate the history of lowland tapir as revealed by variation at the mitochondrial gene Cytochrome b, compare it to the fossil data, and explore mechanisms that could have shaped the observed structure of current populations. Results Separate methodological approaches found mutually exclusive divergence times for lowland tapir, either in the late or in the early Pleistocene, although a late Pleistocene divergence is more in tune with the fossil record. Bayesian analysis favored mountain tapir (T. pinchaque paraphyly in relation to lowland tapir over reciprocal monophyly, corroborating the inferences from the fossil data these species are sister taxa. A coalescent-based analysis rejected a null hypothesis of allopatric divergence, suggesting a complex history. Based on the geographic distribution of haplotypes we propose (i a central role for western Amazonia in tapir diversification, with a key role of the ecological gradient along the transition between Andean subcloud forests and Amazon lowland forest, and (ii that the Amazon river acted as an barrier to gene flow. Finally, the branching patterns and estimates based on nucleotide diversity indicate a population expansion after the Last Glacial Maximum. Conclusions This study is the first examining lowland tapir phylogeography. Climatic events at the end of the Pleistocene, parapatric speciation, divergence along the Andean foothill

Population history, phylogeography, and conservation genetics of the last Neotropical mega-herbivore, the lowland tapir (Tapirus terrestris).

Science.gov (United States)

de Thoisy, Benoit; da Silva, Anders Gonçalves; Ruiz-García, Manuel; Tapia, Andrés; Ramirez, Oswaldo; Arana, Margarita; Quse, Viviana; Paz-y-Miño, César; Tobler, Mathias; Pedraza, Carlos; Lavergne, Anne

2010-09-14

Understanding the forces that shaped Neotropical diversity is central issue to explain tropical biodiversity and inform conservation action; yet few studies have examined large, widespread species. Lowland tapir (Tapirus terrrestris, Perissodactyla, Tapiridae) is the largest Neotropical herbivore whose ancestors arrived in South America during the Great American Biotic Interchange. A Pleistocene diversification is inferred for the genus Tapirus from the fossil record, but only two species survived the Pleistocene megafauna extinction. Here, we investigate the history of lowland tapir as revealed by variation at the mitochondrial gene Cytochrome b, compare it to the fossil data, and explore mechanisms that could have shaped the observed structure of current populations. Separate methodological approaches found mutually exclusive divergence times for lowland tapir, either in the late or in the early Pleistocene, although a late Pleistocene divergence is more in tune with the fossil record. Bayesian analysis favored mountain tapir (T. pinchaque) paraphyly in relation to lowland tapir over reciprocal monophyly, corroborating the inferences from the fossil data these species are sister taxa. A coalescent-based analysis rejected a null hypothesis of allopatric divergence, suggesting a complex history. Based on the geographic distribution of haplotypes we propose (i) a central role for western Amazonia in tapir diversification, with a key role of the ecological gradient along the transition between Andean subcloud forests and Amazon lowland forest, and (ii) that the Amazon river acted as an barrier to gene flow. Finally, the branching patterns and estimates based on nucleotide diversity indicate a population expansion after the Last Glacial Maximum. This study is the first examining lowland tapir phylogeography. Climatic events at the end of the Pleistocene, parapatric speciation, divergence along the Andean foothill, and role of the Amazon river, have similarly shaped

Edible Neotropical Blueberries: Antioxidant and Compositional Fingerprint Analysis

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DASTMALCHI, KEYVAN; FLORES, GEMA; PETROVA, VANYA; PEDRAZA-PEÑALOSA, PAOLA; KENNELLY, EDWARD J.

2012-01-01

Edible blueberry species are well recognized for their potential health benefits. Ericaceae fruits including the North American highbush blueberry (Vaccinium corymbosum L.) and five less common edible blueberry relatives from the New World tropics, Anthopterus wardii Ball, Cavendishia grandifolia Hoerld, Macleania coccoloboides A. C. Sm., Sphyrospermum buxifolium Poepp. & Endl., and Sphyrospermum cordifolium Benth, were investigated for their antioxidant properties and phenolic profiles. The Neotropical berries C. grandifolia and A. wardii exhibited significantly higher DPPH• and ABTS•+ scavenging and iron chelation activities than V. corymbosum. Total phenolic content and HPLC-PDA compositional fingerprint analyses were also carried out. Significant correlations were observed among total phenolic contents, DPPH• and ABTS•+ scavenging, and iron chelation activities. Using HPLC-PDA, the phenolic constituents in the berries were identified as chlorogenic acid, p-coumaric acid, hyperoside, quercetin-3-O-glucoside, isoorientin, isovitexin, orientin and vitexin. Principal components analysis reduced the dimensions of antioxidant and total phenolic data to two components, which accounted for 95% of total variation among the six fruits. Each fruit species formed its own cluster, and therefore the antioxidant profile of each species was shown to be distinct. PMID:21391608

Evaluation of the streaming-matrix method for discrete-ordinates duct-streaming calculations

International Nuclear Information System (INIS)

Clark, B.A.; Urban, W.T.; Dudziak, D.J.

1983-01-01

A new deterministic streaming technique called the Streaming Matrix Hybrid Method (SMHM) is applied to two realistic duct-shielding problems. The results are compared to standard discrete-ordinates and Monte Carlo calculations. The SMHM shows promise as an alternative deterministic streaming method to standard discrete-ordinates

The Effect of Phylogeny, Environment and Morphology on Communities of a Lianescent Clade (Bignonieae-Bignoniaceae) in Neotropical Biomes

Science.gov (United States)

Alcantara, Suzana; Ree, Richard H.; Martins, Fernando R.; Lohmann, Lúcia G.

2014-01-01

The influence of ecological traits to the distribution and abundance of species is a prevalent issue in biodiversity science. Most studies of plant community assembly have focused on traits related to abiotic aspects or direct interactions among plants, with less attention paid to ignore indirect interactions, as those mediated by pollinators. Here, we assessed the influence of phylogeny, habitat, and floral morphology on ecological community structure in a clade of Neotropical lianas (tribe Bignonieae, Bignoniaceae). Our investigation was guided by the long-standing hypothesis that habitat specialization has promoted speciation in Bignonieae, while competition for shared pollinators influences species co-occurrence within communities. We analyzed a geo-referenced database for 94 local communities occurring across the Neotropics. The effect of floral morphological traits and abiotic variables on species co-occurrence was investigated, taking into account phylogenetic relationships. Habitat filtering seems to be the main process driving community assembly in Bignonieae, with environmental conditions limiting species distributions. Differing specialization to abiotic conditions might have evolved recently, in contrast to the general pattern of phylogenetic clustering found in communities of other diverse regions. We find no evidence that competition for pollinators affects species co-occurrence; instead, pollinator occurrence seems to have acted as an “environmental filter” in some habitats. PMID:24594706

Consequences of variation in stream-landscape connections for stream nitrate retention and export

Science.gov (United States)

Handler, A. M.; Helton, A. M.; Grimm, N. B.

2017-12-01

Hydrologic and material connections among streams, the surrounding terrestrial landscape, and groundwater systems fluctuate between extremes in dryland watersheds, yet the consequences of this variation for stream nutrient retention and export remain uncertain. We explored how seasonal variation in hydrologic connection among streams, landscapes, and groundwater affect nitrate and ammonium concentrations across a dryland stream network and how this variation mediates in-stream nitrate uptake and watershed export. We conducted spatial surveys of stream nitrate and ammonium concentration across the 1200 km2 Oak Creek watershed in central Arizona (USA). In addition, we conducted pulse releases of a solution containing biologically reactive sodium nitrate, with sodium chloride as a conservative hydrologic tracer, to estimate nitrate uptake rates in the mainstem (Q>1000 L/s) and two tributaries. Nitrate and ammonium concentrations generally increased from headwaters to mouth in the mainstem. Locally elevated concentrations occurred in spring-fed tributaries draining fish hatcheries and larger irrigation ditches, but did not have a substantial effect on the mainstem nitrogen load. Ambient nitrate concentration (as N) ranged from below the analytical detection limit of 0.005 mg/L to 0.43 mg/L across all uptake experiments. Uptake length—average stream distance traveled for a nutrient atom from the point of release to its uptake—at ambient concentration ranged from 250 to 704 m and increased significantly with higher discharge, both across streams and within the same stream on different experiment dates. Vertical uptake velocity and aerial uptake rate ranged from 6.6-10.6 mm min-1 and 0.03 to 1.4 mg N m-2 min-1, respectively. Preliminary analyses indicate potentially elevated nitrogen loading to the lower portion of the watershed during seasonal precipitation events, but overall, the capacity for nitrate uptake is high in the mainstem and tributaries. Ongoing work

Cross-amplification and characterization of microsatellite loci for the Neotropical orchid genus Epidendrum

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Fábio Pinheiro

2009-01-01

Full Text Available In this study we tested the cross-amplification of 33 microsatellite loci previously developed for two closely related Neotropical orchid genera (Epidendrum and Laelia. A set of ten loci were polymorphic across five examined species (20 individuals each with 2 to 15 alleles per locus. The mean expected and observed heterozygosity (average across species ranged from 0.34 to 0.82 and from 0.27 to 0.85, respectively. In addition we tested all loci in 35 species representative of the genus Epidendrum. Of these, 26 loci showed successful amplification. Cross-application of these loci represent a potential source of co-dominant markers for evolutionary, ecological and conservation studies in this important orchid genus.

Adaptive evolution of facial colour patterns in Neotropical primates.

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Santana, Sharlene E; Lynch Alfaro, Jessica; Alfaro, Michael E

2012-06-07

The rich diversity of primate faces has interested naturalists for over a century. Researchers have long proposed that social behaviours have shaped the evolution of primate facial diversity. However, the primate face constitutes a unique structure where the diverse and potentially competing functions of communication, ecology and physiology intersect, and the major determinants of facial diversity remain poorly understood. Here, we provide the first evidence for an adaptive role of facial colour patterns and pigmentation within Neotropical primates. Consistent with the hypothesis that facial patterns function in communication and species recognition, we find that species living in smaller groups and in sympatry with a higher number of congener species have evolved more complex patterns of facial colour. The evolution of facial pigmentation and hair length is linked to ecological factors, and ecogeographical rules related to UV radiation and thermoregulation are met by some facial regions. Our results demonstrate the interaction of behavioural and ecological factors in shaping one of the most outstanding facial diversities of any mammalian lineage.

Streaming tearing mode

Science.gov (United States)

Shigeta, M.; Sato, T.; Dasgupta, B.

1985-01-01

The magnetohydrodynamic stability of streaming tearing mode is investigated numerically. A bulk plasma flow parallel to the antiparallel magnetic field lines and localized in the neutral sheet excites a streaming tearing mode more strongly than the usual tearing mode, particularly for the wavelength of the order of the neutral sheet width (or smaller), which is stable for the usual tearing mode. Interestingly, examination of the eigenfunctions of the velocity perturbation and the magnetic field perturbation indicates that the streaming tearing mode carries more energy in terms of the kinetic energy rather than the magnetic energy. This suggests that the streaming tearing mode instability can be a more feasible mechanism of plasma acceleration than the usual tearing mode instability.

Evidence for Widespread Associations between Neotropical Hymenopteran Insects and Actinobacteria

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Bernal Matarrita-Carranza

2017-10-01

Full Text Available The evolutionary success of hymenopteran insects has been associated with complex physiological and behavioral defense mechanisms against pathogens and parasites. Among these strategies are symbiotic associations between Hymenoptera and antibiotic-producing Actinobacteria, which provide protection to insect hosts. Herein, we examine associations between culturable Actinobacteria and 29 species of tropical hymenopteran insects that span five families, including Apidae (bees, Vespidae (wasps, and Formicidae (ants. In total, 197 Actinobacteria isolates were obtained from 22 of the 29 different insect species sampled. Through 16S rRNA gene sequences of 161 isolates, we show that 91% of the symbionts correspond to members of the genus Streptomyces with less common isolates belonging to Pseudonocardia and Amycolatopsis. Electron microscopy revealed the presence of filamentous bacteria with Streptomyces morphology in brood chambers of two different species of the eusocial wasps. Four fungal strains in the family Ophiocordycipitacea (Hypocreales known to be specialized insect parasites were also isolated. Bioassay challenges between the Actinobacteria and their possible targeted pathogenic antagonist (both obtained from the same insect at the genus or species level provide evidence that different Actinobacteria isolates produced antifungal activity, supporting the hypothesis of a defensive association between the insects and these microbe species. Finally, phylogenetic analysis of 16S rRNA and gyrB demonstrate the presence of five Streptomyces lineages associated with a broad range of insect species. Particularly our Clade I is of much interest as it is composed of one 16S rRNA phylotype repeatedly isolated from different insect groups in our sample. This phylotype corresponds to a previously described lineage of host-associated Streptomyces. These results suggest Streptomyces Clade I is a Hymenoptera host-associated lineage spanning several new insect

Evidence for Widespread Associations between Neotropical Hymenopteran Insects and Actinobacteria

Science.gov (United States)

Matarrita-Carranza, Bernal; Moreira-Soto, Rolando D.; Murillo-Cruz, Catalina; Mora, Marielos; Currie, Cameron R.; Pinto-Tomas, Adrián A.

2017-01-01

The evolutionary success of hymenopteran insects has been associated with complex physiological and behavioral defense mechanisms against pathogens and parasites. Among these strategies are symbiotic associations between Hymenoptera and antibiotic-producing Actinobacteria, which provide protection to insect hosts. Herein, we examine associations between culturable Actinobacteria and 29 species of tropical hymenopteran insects that span five families, including Apidae (bees), Vespidae (wasps), and Formicidae (ants). In total, 197 Actinobacteria isolates were obtained from 22 of the 29 different insect species sampled. Through 16S rRNA gene sequences of 161 isolates, we show that 91% of the symbionts correspond to members of the genus Streptomyces with less common isolates belonging to Pseudonocardia and Amycolatopsis. Electron microscopy revealed the presence of filamentous bacteria with Streptomyces morphology in brood chambers of two different species of the eusocial wasps. Four fungal strains in the family Ophiocordycipitacea (Hypocreales) known to be specialized insect parasites were also isolated. Bioassay challenges between the Actinobacteria and their possible targeted pathogenic antagonist (both obtained from the same insect at the genus or species level) provide evidence that different Actinobacteria isolates produced antifungal activity, supporting the hypothesis of a defensive association between the insects and these microbe species. Finally, phylogenetic analysis of 16S rRNA and gyrB demonstrate the presence of five Streptomyces lineages associated with a broad range of insect species. Particularly our Clade I is of much interest as it is composed of one 16S rRNA phylotype repeatedly isolated from different insect groups in our sample. This phylotype corresponds to a previously described lineage of host-associated Streptomyces. These results suggest Streptomyces Clade I is a Hymenoptera host-associated lineage spanning several new insect taxa and

The distribution of copper in stream sediments in an anomalous stream near Steinkopf, Namaqualand

International Nuclear Information System (INIS)

De Bruin, D.

1987-01-01

Anomalous copper concentrations detected by the regional stream-sediment programme of the Geological Survey was investigated in a stream near Steinkopf, Namaqualand. A follow-up disclosed the presence of malachite mineralization. However, additional stream-sediment samples collected from the 'anomalous' stream revealed an erratic distribution of copper and also that the malachite mineralization had no direct effect on the copper distribution in the stream sediments. Low partial-extraction yields, together with X-ray diffraction analyses, indicated that dispersion is mainly mechanical and that the copper occurs as cations in the lattice of the biotite fraction of the stream sediments. (author). 8 refs., 5 figs., 1 tab

The distribution of copper in stream sediments in an anomalous stream near Steinkopf, Namaqualand

Energy Technology Data Exchange (ETDEWEB)

De Bruin, D

1987-01-01

Anomalous copper concentrations detected by the regional stream-sediment programme of the Geological Survey was investigated in a stream near Steinkopf, Namaqualand. A follow-up disclosed the presence of malachite mineralization. However, additional stream-sediment samples collected from the 'anomalous' stream revealed an erratic distribution of copper and also that the malachite mineralization had no direct effect on the copper distribution in the stream sediments. Low partial-extraction yields, together with X-ray diffraction analyses, indicated that dispersion is mainly mechanical and that the copper occurs as cations in the lattice of the biotite fraction of the stream sediments. (author). 8 refs., 5 figs., 1 tab.

Yeasts dominate soil fungal communities in three lowland Neotropical rainforests.

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Dunthorn, Micah; Kauserud, Håvard; Bass, David; Mayor, Jordan; Mahé, Frédéric

2017-10-01

Forest soils typically harbour a vast diversity of fungi, but are usually dominated by filamentous (hyphae-forming) taxa. Compared to temperate and boreal forests, though, we have limited knowledge about the fungal diversity in tropical rainforest soils. Here we show, by environmental metabarcoding of soil samples collected in three Neotropical rainforests, that Yeasts dominate the fungal communities in terms of the number of sequencing reads and OTUs. These unicellular forms are commonly found in aquatic environments, and their hyperdiversity may be the result of frequent inundation combined with numerous aquatic microenvironments in these rainforests. Other fungi that are frequent in aquatic environments, such as the abundant Chytridiomycotina, were also detected. While there was low similarity in OTU composition within and between the three rainforests, the fungal communities in Central America were more similar to each other than the communities in South America, reflecting a general biogeographic pattern also seen in animals, plants and protists. © 2017 Society for Applied Microbiology and John Wiley & Sons Ltd.

A morphological comparison of narrow, low-gradient streams traversing wetland environments to alluvial streams.

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Jurmu, Michael C

2002-12-01

Twelve morphological features from research on alluvial streams are compared in four narrow, low-gradient wetland streams located in different geographic regions (Connecticut, Indiana, and Wisconsin, USA). All four reaches differed in morphological characteristics in five of the features compared (consistent bend width, bend cross-sectional shape, riffle width compared to pool width, greatest width directly downstream of riffles, and thalweg location), while three reaches differed in two comparisons (mean radius of curvature to width ratio and axial wavelength to width ratio). The remaining five features compared had at least one reach where different characteristics existed. This indicates the possibility of varying morphology for streams traversing wetland areas further supporting the concept that the unique qualities of wetland environments might also influence the controls on fluvial dynamics and the development of streams. If certain morphological features found in streams traversing wetland areas differ from current fluvial principles, then these varying features should be incorporated into future wetland stream design and creation projects. The results warrant further research on other streams traversing wetlands to determine if streams in these environments contain unique morphology and further investigation of the impact of low-energy fluvial processes on morphological development. Possible explanations for the morphology deviations in the study streams and some suggestions for stream design in wetland areas based upon the results and field observations are also presented.

Polyphyly of the hawk genera Leucopternis and Buteogallus (Aves, Accipitridae): multiple habitat shifts during the Neotropical buteonine diversification

OpenAIRE

do Amaral, Fabio S Raposo; Miller, Matthew J; Silveira, Luís Fábio; Bermingham, Eldredge; Wajntal, Anita

2006-01-01

Abstract Background The family Accipitridae (hawks, eagles and Old World vultures) represents a large radiation of predatory birds with an almost global distribution, although most species of this family occur in the Neotropics. Despite great morphological and ecological diversity, the evolutionary relationships in the family have been poorly explored at all taxonomic levels. Using sequences from four mitochondrial genes (12S, ATP8, ATP6, and ND6), we reconstructed the phylogeny of the Neotro...

InSTREAM: the individual-based stream trout research and environmental assessment model

Science.gov (United States)

Steven F. Railsback; Bret C. Harvey; Stephen K. Jackson; Roland H. Lamberson

2009-01-01

This report documents Version 4.2 of InSTREAM, including its formulation, software, and application to research and management problems. InSTREAM is a simulation model designed to understand how stream and river salmonid populations respond to habitat alteration, including altered flow, temperature, and turbidity regimes and changes in channel morphology. The model...

Re-Meandering of Lowland Streams

DEFF Research Database (Denmark)

Pedersen, Morten Lauge; Kristensen, Klaus Kevin; Friberg, Nikolai

2014-01-01

We evaluated the restoration of physical habitats and its influence on macroinvertebrate community structure in 18 Danish lowland streams comprising six restored streams, six streams with little physical alteration and six channelized streams. We hypothesized that physical habitats and macroinver...

Analysis Of DWPF Sludge Batch 7A (Macrobatch 8) Pour Stream Samples

International Nuclear Information System (INIS)

Johnson, F.

2012-01-01

The Defense Waste Processing Facility (DWPF) began processing Sludge Batch 7a (SB7a), also referred to as Macrobatch 8 (MB8), in June 2011. SB7a is a blend of the heel of Tank 40 from Sludge Batch 6 (SB6) and the SB7a material that was transferred to Tank 40 from Tank 51. SB7a was processed using Frit 418. During processing of each sludge batch, the DWPF is required to take at least one glass sample to meet the objectives of the Glass Product Control Program (GPCP), which is governed by the DWPF Waste Compliance Plan, and to complete the necessary Production Records so that the final glass product may be disposed of at a Federal Repository. Three pour stream glass samples and two Melter Feed Tank (MFT) slurry samples were collected while processing SB7a. These additional samples were taken during SB7a to understand the impact of antifoam and the melter bubblers on glass redox chemistry. The samples were transferred to the Savannah River National Laboratory (SRNL) where they were analyzed. The following conclusions were drawn from the analytical results provided in this report: (1) The sum of oxides for the official SB7a pour stream glass is within the Product Composition Control System (PCCS) limits (95-105 wt%). (2) The average calculated Waste Dilution Factor (WDF) for SB7a is 2.3. In general, the measured radionuclide content of the official SB7a pour stream glass is in good agreement with the calculated values from the Tank 40 dried sludge results from the SB7a Waste Acceptance Program Specification (WAPS) sample. (3) As in previous pour stream samples, ruthenium and rhodium inclusions were detected by Scanning Electron Microscopy-Electron Dispersive Spectroscopy (SEM-EDS) in the official SB7a pour stream sample. (4) The Product Consistency Test (PCT) results indicate that the official SB7a pour stream glass meets the waste acceptance criteria for durability with a normalized boron release of 0.64 g/L, which is an order of magnitude less than the Environmental

Redescription of Japanagromyza inferna Spencer, first recorded from Brazil, and a key to the Neotropical species of Japanagromyza Sasakawa (Diptera, Agromyzidae

Directory of Open Access Journals (Sweden)

Viviane de Sousa

2014-01-01

Full Text Available Japanagromyza inferna Spencer is recorded for the first time from Brazil, in the North coast of the State of Rio de Janeiro, inducing galls in Centrosema virginianum L. (Fabaceae. The species is redescribed, with illustrations of male and female terminalia. A key to the identification of the Neotropical species of Japanagromyza Sasakawa is presented.

Underestimation of species richness in neotropical frogs revealed by mtDNA analyses.

Directory of Open Access Journals (Sweden)

Antoine Fouquet

2007-10-01

Full Text Available Amphibians are rapidly vanishing. At the same time, it is most likely that the number of amphibian species is highly underestimated. Recent DNA barcoding work has attempted to define a threshold between intra- and inter-specific genetic distances to help identify candidate species. In groups with high extinction rates and poorly known species boundaries, like amphibians, such tools may provide a way to rapidly evaluate species richness.Here we analyse published and new 16S rDNA sequences from 60 frog species of Amazonia-Guianas to obtain a minimum estimate of the number of undescribed species in this region. We combined isolation by distance, phylogenetic analyses, and comparison of molecular distances to evaluate threshold values for the identification of candidate species among these frogs.In most cases, geographically distant populations belong to genetically highly distinct lineages that could be considered as candidate new species. This was not universal among the taxa studied and thus widespread species of Neotropical frogs really do exist, contrary to previous assumptions. Moreover, the many instances of paraphyly and the wide overlap between distributions of inter- and intra-specific distances reinforce the hypothesis that many cryptic species remain to be described. In our data set, pairwise genetic distances below 0.02 are strongly correlated with geographical distances. This correlation remains statistically significant until genetic distance is 0.05, with no such relation thereafter. This suggests that for higher distances allopatric and sympatric cryptic species prevail. Based on our analyses, we propose a more inclusive pairwise genetic distance of 0.03 between taxa to target lineages that could correspond to candidate species.Using this approach, we identify 129 candidate species, two-fold greater than the 60 species included in the current study. This leads to estimates of around 170 to 460 frog taxa unrecognized in Amazonia

Streaming current magnetic fields in a charged nanopore

Science.gov (United States)

Mansouri, Abraham; Taheri, Peyman; Kostiuk, Larry W.

2016-01-01

Magnetic fields induced by currents created in pressure driven flows inside a solid-state charged nanopore were modeled by numerically solving a system of steady state continuum partial differential equations, i.e., Poisson, Nernst-Planck, Ampere and Navier-Stokes equations (PNPANS). This analysis was based on non-dimensional transport governing equations that were scaled using Debye length as the characteristic length scale, and applied to a finite length cylindrical nano-channel. The comparison of numerical and analytical studies shows an excellent agreement and verified the magnetic fields density both inside and outside the nanopore. The radially non-uniform currents resulted in highly non-uniform magnetic fields within the nanopore that decay as 1/r outside the nanopore. It is worth noting that for either streaming currents or streaming potential cases, the maximum magnetic field occurred inside the pore in the vicinity of nanopore wall, as opposed to a cylindrical conductor that carries a steady electric current where the maximum magnetic fields occur at the perimeter of conductor. Based on these results, it is suggested and envisaged that non-invasive external magnetic fields readouts generated by streaming/ionic currents may be viewed as secondary electronic signatures of biomolecules to complement and enhance current DNA nanopore sequencing techniques. PMID:27833119

Experimental investigation of acoustic streaming in a cylindrical wave guide up to high streaming Reynolds numbers.

Science.gov (United States)

Reyt, Ida; Bailliet, Hélène; Valière, Jean-Christophe

2014-01-01

Measurements of streaming velocity are performed by means of Laser Doppler Velocimetry and Particle Image Velociimetry in an experimental apparatus consisting of a cylindrical waveguide having one loudspeaker at each end for high intensity sound levels. The case of high nonlinear Reynolds number ReNL is particularly investigated. The variation of axial streaming velocity with respect to the axial and to the transverse coordinates are compared to available Rayleigh streaming theory. As expected, the measured streaming velocity agrees well with the Rayleigh streaming theory for small ReNL but deviates significantly from such predictions for high ReNL. When the nonlinear Reynolds number is increased, the outer centerline axial streaming velocity gets distorted towards the acoustic velocity nodes until counter-rotating additional vortices are generated near the acoustic velocity antinodes. This kind of behavior is followed by outer streaming cells only and measurements in the near wall region show that inner streaming vortices are less affected by this substantial evolution of fast streaming pattern. Measurements of the transient evolution of streaming velocity provide an additional insight into the evolution of fast streaming.

[New species, newly used names and new ranges of tree ferns (Filicales: Cyatheaceae) in the Neotropics].

Science.gov (United States)

Rojas-Alvarado, A F

2001-06-01

Two new species are described for the Neotropics, four species are newly accepted, and four species and one variety are reported. The new species are: Cyathea grayumii A. Rojas and C. panamensis A. Rojas. Cyathea alfonsiana L. D. Gómez, C. holdridgeana Nisman & L. D. Gómez, C. onusta H. Christ and C. squarrosa (Rosenst.) Domin are recognized; Cnemidaria coclena Stolze, Cyathea andina (H. Karst.) Domin, C. caracasana var. meridensis (H. Karst.) R. M. Tryon, C. macrosora (Baker) Domin and C. pseudonanna (L. D. Gómez) Lellinger are reported from Costa Rica and Panama.

A Statistical Method to Predict Flow Permanence in Dryland Streams from Time Series of Stream Temperature

Directory of Open Access Journals (Sweden)

Ivan Arismendi

2017-12-01

Full Text Available Intermittent and ephemeral streams represent more than half of the length of the global river network. Dryland freshwater ecosystems are especially vulnerable to changes in human-related water uses as well as shifts in terrestrial climates. Yet, the description and quantification of patterns of flow permanence in these systems is challenging mostly due to difficulties in instrumentation. Here, we took advantage of existing stream temperature datasets in dryland streams in the northwest Great Basin desert, USA, to extract critical information on climate-sensitive patterns of flow permanence. We used a signal detection technique, Hidden Markov Models (HMMs, to extract information from daily time series of stream temperature to diagnose patterns of stream drying. Specifically, we applied HMMs to time series of daily standard deviation (SD of stream temperature (i.e., dry stream channels typically display highly variable daily temperature records compared to wet stream channels between April and August (2015–2016. We used information from paired stream and air temperature data loggers as well as co-located stream temperature data loggers with electrical resistors as confirmatory sources of the timing of stream drying. We expanded our approach to an entire stream network to illustrate the utility of the method to detect patterns of flow permanence over a broader spatial extent. We successfully identified and separated signals characteristic of wet and dry stream conditions and their shifts over time. Most of our study sites within the entire stream network exhibited a single state over the entire season (80%, but a portion of them showed one or more shifts among states (17%. We provide recommendations to use this approach based on a series of simple steps. Our findings illustrate a successful method that can be used to rigorously quantify flow permanence regimes in streams using existing records of stream temperature.

A statistical method to predict flow permanence in dryland streams from time series of stream temperature

Science.gov (United States)

Arismendi, Ivan; Dunham, Jason B.; Heck, Michael; Schultz, Luke; Hockman-Wert, David

2017-01-01

Intermittent and ephemeral streams represent more than half of the length of the global river network. Dryland freshwater ecosystems are especially vulnerable to changes in human-related water uses as well as shifts in terrestrial climates. Yet, the description and quantification of patterns of flow permanence in these systems is challenging mostly due to difficulties in instrumentation. Here, we took advantage of existing stream temperature datasets in dryland streams in the northwest Great Basin desert, USA, to extract critical information on climate-sensitive patterns of flow permanence. We used a signal detection technique, Hidden Markov Models (HMMs), to extract information from daily time series of stream temperature to diagnose patterns of stream drying. Specifically, we applied HMMs to time series of daily standard deviation (SD) of stream temperature (i.e., dry stream channels typically display highly variable daily temperature records compared to wet stream channels) between April and August (2015–2016). We used information from paired stream and air temperature data loggers as well as co-located stream temperature data loggers with electrical resistors as confirmatory sources of the timing of stream drying. We expanded our approach to an entire stream network to illustrate the utility of the method to detect patterns of flow permanence over a broader spatial extent. We successfully identified and separated signals characteristic of wet and dry stream conditions and their shifts over time. Most of our study sites within the entire stream network exhibited a single state over the entire season (80%), but a portion of them showed one or more shifts among states (17%). We provide recommendations to use this approach based on a series of simple steps. Our findings illustrate a successful method that can be used to rigorously quantify flow permanence regimes in streams using existing records of stream temperature.

StreamQRE: Modular Specification and Efficient Evaluation of Quantitative Queries over Streaming Data.

Science.gov (United States)

Mamouras, Konstantinos; Raghothaman, Mukund; Alur, Rajeev; Ives, Zachary G; Khanna, Sanjeev

2017-06-01

Real-time decision making in emerging IoT applications typically relies on computing quantitative summaries of large data streams in an efficient and incremental manner. To simplify the task of programming the desired logic, we propose StreamQRE, which provides natural and high-level constructs for processing streaming data. Our language has a novel integration of linguistic constructs from two distinct programming paradigms: streaming extensions of relational query languages and quantitative extensions of regular expressions. The former allows the programmer to employ relational constructs to partition the input data by keys and to integrate data streams from different sources, while the latter can be used to exploit the logical hierarchy in the input stream for modular specifications. We first present the core language with a small set of combinators, formal semantics, and a decidable type system. We then show how to express a number of common patterns with illustrative examples. Our compilation algorithm translates the high-level query into a streaming algorithm with precise complexity bounds on per-item processing time and total memory footprint. We also show how to integrate approximation algorithms into our framework. We report on an implementation in Java, and evaluate it with respect to existing high-performance engines for processing streaming data. Our experimental evaluation shows that (1) StreamQRE allows more natural and succinct specification of queries compared to existing frameworks, (2) the throughput of our implementation is higher than comparable systems (for example, two-to-four times greater than RxJava), and (3) the approximation algorithms supported by our implementation can lead to substantial memory savings.

Enhancement of electron flux by means of diamond membrane

International Nuclear Information System (INIS)

Gavrilov, S.A.; Il'ichev, Eh.A.; Poltoratskij, Eh.A.; Rychkov, G.S.; Dzbanovskij, N.N.; Minakov, P.V.; Suetin, N.V.

2004-01-01

One investigates into secondary electron emission (SEE) from diamond films made in the form of 2.5-5 μm thickness membranes. SEE is investigated under two modes: the reflection and the streaming ones. SEE coefficient is evaluated on the basis of analysis of behavior of 0.1-30 keV energy electrons in solid material. It is shown that in case of reflection the SEE coefficient may be over 100 at energies equal to 3 keV, while in case of streaming it does not exceed 5 even at 30 keV energy values [ru

Air-electron stream interactions during magnetic resonance IGRT. Skin irradiation outside the treatment field during accelerated partial breast irradiation

Energy Technology Data Exchange (ETDEWEB)

Park, Jong Min [Seoul National University Hospital, Department of Radiation Oncology, Seoul (Korea, Republic of); Seoul National University Hospital, Biomedical Research Institute, Seoul (Korea, Republic of); Seoul National University Medical Research Center, Institute of Radiation Medicine, Seoul (Korea, Republic of); Advanced Institutes of Convergence Technology, Robotics Research Laboratory for Extreme Environments, Suwon (Korea, Republic of); Shin, Kyung Hwan; Wu, Hong-Gyun [Seoul National University Hospital, Department of Radiation Oncology, Seoul (Korea, Republic of); Seoul National University Hospital, Biomedical Research Institute, Seoul (Korea, Republic of); Seoul National University Medical Research Center, Institute of Radiation Medicine, Seoul (Korea, Republic of); Seoul National University College of Medicine, Department of Radiation Oncology, Seoul (Korea, Republic of); Kim, Jung-in; Park, So-Yeon; Kim, Jin Ho [Seoul National University Hospital, Department of Radiation Oncology, Seoul (Korea, Republic of); Seoul National University Hospital, Biomedical Research Institute, Seoul (Korea, Republic of); Seoul National University Medical Research Center, Institute of Radiation Medicine, Seoul (Korea, Republic of); Jeon, Seung Hyuck [Seoul National University Hospital, Department of Radiation Oncology, Seoul (Korea, Republic of); Choi, Noorie [Seoul National University College of Medicine, Department of Radiation Oncology, Seoul (Korea, Republic of)

2018-01-15

To investigate and to prevent irradiation outside the treatment field caused by an electron stream in the air generated by the magnetic field during magnetic resonance image-guided accelerated partial breast irradiation (APBI). In all, 20 patients who received APBI with a magnetic resonance image-guided radiation therapy (MR-IGRT) system were prospectively studied. The prescription dose was 38.5 Gy in 10 fractions of 3.85 Gy and delivered with a tri-cobalt system (the ViewRay system). For each patient, primary plans were delivered for the first five fractions and modified plans with different gantry angles from those of the primary plan (in-treatment plans) were delivered for the remaining five fractions to reduce the skin dose. A 1 cm thick bolus was placed in front of the patient's jaw, ipsilateral shoulder, and arm to shield them from the electron stream. Radiochromic EBT3 films were attached to the front (towards the breast) and back (towards the head) of the bolus during treatment. Correlations between the measured values and the tumor locations, treatment times, and tumor sizes were investigated. For a single fraction delivery, the average areas of the measured isodoses of 14% (0.54 Gy), 12% (0.46 Gy), and 10% (0.39 Gy) at the front of the boluses were as large as 3, 10.4, and 21.4 cm{sup 2}, respectively, whereas no significant dose could be measured at the back of the boluses. Statistically significant but weak correlations were observed between the measured values and the treatment times. During radiotherapy for breast cancer with an MR-IGRT system, the patient must be shielded from electron streams in the air generated by the interaction of the magnetic field with the beams of the three-cobalt treatment unit to avoid unwanted irradiation of the skin outside the treatment field. (orig.) [German] Beim Einsatz eines Magnetresonanztomographie(MRT)-gefuehrten Bestrahlungsgeraets kann durch die Wechselwirkung von Magnetfeld und Strahlenquelle unerwuenscht

Productivity of Stream Definitions

NARCIS (Netherlands)

Endrullis, Jörg; Grabmayer, Clemens; Hendriks, Dimitri; Isihara, Ariya; Klop, Jan

2007-01-01

We give an algorithm for deciding productivity of a large and natural class of recursive stream definitions. A stream definition is called ‘productive’ if it can be evaluated continuously in such a way that a uniquely determined stream is obtained as the limit. Whereas productivity is undecidable

Productivity of stream definitions

NARCIS (Netherlands)

Endrullis, J.; Grabmayer, C.A.; Hendriks, D.; Isihara, A.; Klop, J.W.

2008-01-01

We give an algorithm for deciding productivity of a large and natural class of recursive stream definitions. A stream definition is called ‘productive’ if it can be evaluated continually in such a way that a uniquely determined stream in constructor normal form is obtained as the limit. Whereas

Simulation and reconstruction of free-streaming data in CBM

International Nuclear Information System (INIS)

Friese, Volker

2011-01-01

The CBM experiment will investigate heavy-ion reactions at the FAIR facility at unprecedented interaction rates. This implies a novel read-out and data acquisition concept with self-triggered front-end electronics and free-streaming data. Event association must be performed in software on-line, and may require four-dimensional reconstruction routines. In order to study the problem of event association and to develop proper algorithms, simulations must be performed which go beyond the normal event-by-event processing as available from most experimental simulation frameworks. In this article, we discuss the challenges and concepts for the reconstruction of such free-streaming data and present first steps for a time-based simulation which is necessary for the development and validation of the reconstruction algorithms, and which requires modifications to the current software framework FAIRROOT as well as to the data model.

Observations of field-aligned energetic electron and ion distributions near the magnetopause at geosynchronous orbit

International Nuclear Information System (INIS)

Korth, A.; Kremser, G.; Daly, P.W.; Amata, E.

1982-01-01

On August 28, 1978, the dayside magnetopause crossed the geosynchronous satellite GEOS 2 several times during a geomagnetically disturbed period, and clear signatures of the interconnection of field lines through the magnetopause were observed. The MPAE particle spectrometer provided high time resolution observations of the distribution of energetic electrons (E>22 keV) and ions (E>27 keV). Magnetometer data were used to determine the location of GEOS 2 relative to the magnetopause. The pitch angle distributions of ions and electrons were found to be strongly asymmetric with respect to 90 0 , and the asymmetries have been interpreted in terms of field-aligned particle streaming. Evidence is provided for the first time for electron streaming inside the magnetopause which continues for many bounce periods. It is concluded that magnetospheric field lines opened, at least for brief time intervals, as a consequence of interconnection with magnetosheath field lines. Comparisons of electron spectra provide evidence that the streaming electrons observed in the magnetosheath originate in the magnetosphere

Streams and their future inhabitants

DEFF Research Database (Denmark)

Sand-Jensen, K.; Friberg, Nikolai

2006-01-01

In this fi nal chapter we look ahead and address four questions: How do we improve stream management? What are the likely developments in the biological quality of streams? In which areas is knowledge on stream ecology insuffi cient? What can streams offer children of today and adults of tomorrow?...

Salamander occupancy in headwater stream networks

Science.gov (United States)

Grant, E.H.C.; Green, L.E.; Lowe, W.H.

2009-01-01

1. Stream ecosystems exhibit a highly consistent dendritic geometry in which linear habitat units intersect to create a hierarchical network of connected branches. 2. Ecological and life history traits of species living in streams, such as the potential for overland movement, may interact with this architecture to shape patterns of occupancy and response to disturbance. Specifically, large-scale habitat alteration that fragments stream networks and reduces connectivity may reduce the probability a stream is occupied by sensitive species, such as stream salamanders. 3. We collected habitat occupancy data on four species of stream salamanders in first-order (i.e. headwater) streams in undeveloped and urbanised regions of the eastern U.S.A. We then used an information-theoretic approach to test alternative models of salamander occupancy based on a priori predictions of the effects of network configuration, region and salamander life history. 4. Across all four species, we found that streams connected to other first-order streams had higher occupancy than those flowing directly into larger streams and rivers. For three of the four species, occupancy was lower in the urbanised region than in the undeveloped region. 5. These results demonstrate that the spatial configuration of stream networks within protected areas affects the occurrences of stream salamander species. We strongly encourage preservation of network connections between first-order streams in conservation planning and management decisions that may affect stream species.

New Pesticidal Diterpenoids from Vellozia gigantea (Velloziaceae, an Endemic Neotropical Plant Living in the Endangered Brazilian Biome Rupestrian Grasslands

Directory of Open Access Journals (Sweden)

Mariana C. Ferreira

2017-01-01

Full Text Available Vellozia gigantea is a rare, ancient, and endemic neotropical plant present in the Brazilian Rupestrian grasslands. The dichloromethane extract of V. gigantea adventitious roots was phytotoxic against Lactuca sativa, Agrostis stolonifera, and Lemna paucicostata, and showed larvicidal activity against Aedes aegypti. Phytotoxicity bioassay-directed fractionation of the extract revealed one new isopimaradiene, 8(9,15-isopimaradien-1,3,7,11-tetraone, and three new cleistanthane diterpenoids, 7-oxo-8,11,13-cleistanthatrien-3-ol, 3,20-epoxy-7-oxo-8,11,13-cleistanthatrien-3-ol, and 20-nor-3,7-dioxo-1,8,11,13-cleistanthatetraen-10-ol. These new structures are proposed based on interpretation of 1H, 13C, COSY, NOESY, HSQC, and HMBC NMR data. 8(9,15-isopimaradien-1,3,7,11-tetraone was especially phytotoxic with an IC50 value (30 μM comparable to those of commercial herbicides clomazone, EPTC, and naptalam. In addition, 7-oxo-8,11,13-cleistanthatrien-3-ol provided 100% mortality at a concentration of 125 ppm against one-day-old Ae. aegypti larvae. Our results show that ancient and unique plants, like the endangered narrowly endemic neotropical species V. gigantea present in the Rupestrian grasslands, should also be protected because they can be sources of new bioactive compounds.

Stream hydraulics and temperature determine the metabolism of geothermal Icelandic streams

Directory of Open Access Journals (Sweden)

Demars B. O.L.

2011-07-01

Full Text Available Stream ecosystem metabolism plays a critical role in planetary biogeochemical cycling. Stream benthic habitat complexity and the available surface area for microbes relative to the free-flowing water volume are thought to be important determinants of ecosystem metabolism. Unfortunately, the engineered deepening and straightening of streams for drainage purposes could compromise stream natural services. Stream channel complexity may be quantitatively expressed with hydraulic parameters such as water transient storage, storage residence time, and water spiralling length. The temperature dependence of whole stream ecosystem respiration (ER, gross primary productivity (GPP and net ecosystem production (NEP = GPP − ER has recently been evaluated with a “natural experiment” in Icelandic geothermal streams along a 5–25 °C temperature gradient. There remained, however, a substantial amount of unexplained variability in the statistical models, which may be explained by hydraulic parameters found to be unrelated to temperature. We also specifically tested the additional and predicted synergistic effects of water transient storage and temperature on ER, using novel, more accurate, methods. Both ER and GPP were highly related to water transient storage (or water spiralling length but not to the storage residence time. While there was an additional effect of water transient storage and temperature on ER (r2 = 0.57; P = 0.015, GPP was more related to water transient storage than temperature. The predicted synergistic effect could not be confirmed, most likely due to data limitation. Our interpretation, based on causal statistical modelling, is that the metabolic balance of streams (NEP was primarily determined by the temperature dependence of respiration. Further field and experimental work is required to test the predicted synergistic effect on ER. Meanwhile, since higher metabolic activities allow for higher pollutant degradation or uptake

Paternal Effort in Relation to Acoustically Mediated Mate Choice in a Neotropical Frog

Science.gov (United States)

Pettitt, Beth Ann

One aspect of communication not normally considered in studies of anuran amphibians involves the extent to which acoustic signals indicate the quality of parental care a male provides. My research examined this question in the golden rocket frog (Anomaloglossus beebei), a Neotropical dendrobatid that exhibits acoustically mediated mate choice and biparental care. I investigated the function of the male advertisement call of A. beebei in the context of female mate choice by testing the predictions of four hypotheses that have been proposed to explain the relationship between mate signals and male parental care quality. In addition, I conducted a series of studies on acoustic variability, female preferences for advertisement call traits and the importance of male parental care on offspring survival.

Ground-based thermal imaging of stream surface temperatures: Technique and evaluation

Science.gov (United States)

Bonar, Scott A.; Petre, Sally J.

2015-01-01

We evaluated a ground-based handheld thermal imaging system for measuring water temperatures using data from eight southwestern USA streams and rivers. We found handheld thermal imagers could provide considerably more spatial information on water temperature (for our unit one image = 19,600 individual temperature measurements) than traditional methods could supply without a prohibitive amount of effort. Furthermore, they could provide measurements of stream surface temperature almost instantaneously compared with most traditional handheld thermometers (e.g., >20 s/reading). Spatial temperature analysis is important for measurement of subtle temperature differences across waterways, and identification of warm and cold groundwater inputs. Handheld thermal imaging is less expensive and equipment intensive than airborne thermal imaging methods and is useful under riparian canopies. Disadvantages of handheld thermal imagers include their current higher expense than thermometers, their susceptibility to interference when used incorrectly, and their slightly lower accuracy than traditional temperature measurement methods. Thermal imagers can only measure surface temperature, but this usually corresponds to subsurface temperatures in well-mixed streams and rivers. Using thermal imaging in select applications, such as where spatial investigations of water temperature are needed, or in conjunction with stationary temperature data loggers or handheld electronic or liquid-in-glass thermometers to characterize stream temperatures by both time and space, could provide valuable information on stream temperature dynamics. These tools will become increasingly important to fisheries biologists as costs continue to decline.

Vector-borne transmission of Trypanosoma cruzi among captive Neotropical primates in a Brazilian zoo.

Science.gov (United States)

Minuzzi-Souza, Thaís Tâmara Castro; Nitz, Nadjar; Knox, Monique Britto; Reis, Filipe; Hagström, Luciana; Cuba, César A Cuba; Hecht, Mariana Machado; Gurgel-Gonçalves, Rodrigo

2016-01-26

Neotropical primates are important sylvatic hosts of Trypanosoma cruzi, the etiological agent of Chagas disease. Infection is often subclinical, but severe disease has been described in both free-ranging and captive primates. Panstrongylus megistus, a major T. cruzi vector, was found infesting a small-primate unit at Brasília zoo (ZooB), Brazil. ZooB lies close to a gallery-forest patch where T. cruzi circulates naturally. Here, we combine parasitological and molecular methods to investigate a focus of T. cruzi infection involving triatomine bugs and Neotropical primates at a zoo located in the Brazilian Savannah. We assessed T. cruzi infection in vectors using optical microscopy (n = 34) and nested PCR (n = 50). We used quantitative PCR (qPCR) to examine blood samples from 26 primates and necropsy samples from two primates that died during the study. We determined parasite lineages in five vectors and two primates by comparing glucose-6-phosphate isomerase (G6pi) gene sequences. Trypanosoma cruzi was found in 44 vectors and 17 primates (six genera and eight species); one Mico chrysoleucus and one Saguinus niger had high parasitaemias. Trypanosoma cruzi DNA was detected in three primates born to qPCR-negative mothers at ZooB and in the two dead specimens. One Callithrix geoffroyi became qPCR-positive over a two-year follow-up. All G6pi sequences matched T. cruzi lineage TcI. Our findings strongly suggest vector-borne T. cruzi transmission within a small-primate unit at ZooB - with vectors, and perhaps also parasites, presumably coming from nearby gallery forest. Periodic checks for vectors and parasites would help eliminate T. cruzi transmission foci in captive-animal facilities. This should be of special importance for captive-breeding programs involving endangered mammals, and would reduce the risk of accidental T. cruzi transmission to keepers and veterinarians.

Nitrogen saturation in stream ecosystems.

Science.gov (United States)

Earl, Stevan R; Valett, H Maurice; Webster, Jackson R

2006-12-01

The concept of nitrogen (N) saturation has organized the assessment of N loading in terrestrial ecosystems. Here we extend the concept to lotic ecosystems by coupling Michaelis-Menten kinetics and nutrient spiraling. We propose a series of saturation response types, which may be used to characterize the proximity of streams to N saturation. We conducted a series of short-term N releases using a tracer (15NO3-N) to measure uptake. Experiments were conducted in streams spanning a gradient of background N concentration. Uptake increased in four of six streams as NO3-N was incrementally elevated, indicating that these streams were not saturated. Uptake generally corresponded to Michaelis-Menten kinetics but deviated from the model in two streams where some other growth-critical factor may have been limiting. Proximity to saturation was correlated to background N concentration but was better predicted by the ratio of dissolved inorganic N (DIN) to soluble reactive phosphorus (SRP), suggesting phosphorus limitation in several high-N streams. Uptake velocity, a reflection of uptake efficiency, declined nonlinearly with increasing N amendment in all streams. At the same time, uptake velocity was highest in the low-N streams. Our conceptual model of N transport, uptake, and uptake efficiency suggests that, while streams may be active sites of N uptake on the landscape, N saturation contributes to nonlinear changes in stream N dynamics that correspond to decreased uptake efficiency.

Taxonomy and phenotypic relationships of the Anastrepha fraterculus complex in the Mesoamerican and Pacific Neotropical dominions (Diptera, Tephritidae)

Science.gov (United States)

Hernández-Ortiz, Vicente; Canal, Nelson A.; Salas, Juan O. Tigrero; Ruíz-Hurtado, Freddy M.; Dzul-Cauich, José F.

2015-01-01

Abstract Previous morphometric studies based on linear measurements of female structures of the aculeus, mesonotum, and wing revealed the existence of seven morphotypes within the Anastrepha fraterculus cryptic species complex along the Neotropical Region. The current research followed linear and geometric morphometric approaches in 40 population samples of the nominal species Anastrepha fraterculus (Wiedemann) spread throughout the Meso-American and Pacific Neotropical dominions (including Mexico, Central America, Venezuela, Colombia, Ecuador, and Peru). The goals were to explore the phenotypic relationships of the morphotypes in these biogeographical areas; evaluate the reliability of procedures used for delimitation of morphotypes; and describe their current distribution. Findings determined that morphotypes previously recognized via the linear morphometrics were also supported by geometric morphometrics of the wing shape. In addition, we found an eighth morphotype inhabiting the highlands of Ecuador and Peru. Morphotypes are related into three natural phenotypic groups nominated as Mesoamerican-Caribbean lineage, Andean lineage, and Brazilian lineage. The hypothesis that lineages are not directly related to each other is discussed, supported by their large morphological divergence and endemicity in these three well-defined biogeographic areas. In addition, this hypothesis of the non-monophyly of the Anastrepha fraterculus complex is also supported by evidence from other authors based on molecular studies and the strong reproductive isolation between morphs from different lineages. PMID:26798256

Coronal Magnetic Field Lines and Electrons Associated with Type III

Indian Academy of Sciences (India)

Coronal Magnetic Field Lines and Electrons Associated with Type III–V Radio Bursts in a Solar Flare ... velocities of the electron streams associated with the above two types of bursts indicate ... Journal of Astrophysics and Astronomy | News ...

Towards a robust systematic baseline of Neotropical fish tapeworms (Cestoda: Proteocephalidae): amended diagnoses of two genera from the redtail catfish, Phractocephalus hemioliopterus

Czech Academy of Sciences Publication Activity Database

Alves, Philippe Vieira; de Chambrier, A.; Luque, J.L.; Scholz, Tomáš

2018-01-01

Roč. 4370, č. 4 (2018), s. 363-380 ISSN 1175-5326 R&D Projects: GA ČR(CZ) GBP505/12/G112 Institutional support: RVO:60077344 Keywords : cestodes * Ephedrocephalus * Zygobothrium * taxonomy * morphology * phylogenetic relationships * Amazon River basin * South America * Neotropical region Subject RIV: EG - Zoology OBOR OECD: Zoology Impact factor: 0.972, year: 2016

An illustrated key to Neotropical species of the genus Meteorus Haliday (Hymenoptera, Braconidae, Euphorinae

Directory of Open Access Journals (Sweden)

Helmuth Aguirre

2015-03-01

Full Text Available A comprehensive key for 75 species of Meteorus distributed across 15 Neotropical countries is presented. Eleven new species from Bolivia, Costa Rica and Ecuador are described: M. albistigma, M. carolae, M. eurysaccavorus, M. fallacavus, M. flavistigma, M. haimowitzi, M. magnoculus, M. martinezi, M. microcavus, M. noctuivorus and M. orion. Expanded range distributions are recorded for M. andreae, M. farallonensis, M. guineverae, M. jerodi, M. kraussi, M. papiliovorus and M. quimbayensis. The host of M. jerodi is reported for the first time: a noctuid larva feeding on Asteraceae. Meteorus papiliovorus is recorded attacking Papilionidae larvae in Ecuador, therefore displaying a similar host family preference as formerly documented from Costa Rica and Colombia.

Reappraisal of Goezeella Fuhrmann, 1916 (Cestoda: Proteocephalidae), parasites of Neotropical catfi shes (Siluriformes), with description of a new species from Pimelodella cristata (Heptapteridae)

Czech Academy of Sciences Publication Activity Database

Alves, Philippe Vieira; de Chambrier, A.; Luque, J.L.; Scholz, Tomáš

19 June, č. 124 (2017), s. 335-350 ISSN 0035-418X R&D Projects: GA ČR(CZ) GBP505/12/G112 Institutional support: RVO:60077344 Keywords : morphology * taxonomy * tapeworms * Onchoproteocephalidea * systematics * host-associations * Neotropical Region * South America Subject RIV: EG - Zoology OBOR OECD: Zoology Impact factor: 0.380, year: 2016

Integrative taxonomy supports new candidate fish species in a poorly studied neotropical region: the Jequitinhonha River Basin.

Science.gov (United States)

Pugedo, Marina Lages; de Andrade Neto, Francisco Ricardo; Pessali, Tiago Casarim; Birindelli, José Luís Olivan; Carvalho, Daniel Cardoso

2016-06-01

Molecular identification through DNA barcoding has been proposed as a way to standardize a global biodiversity identification system using a partial sequence of the mitochondrial COI gene. We applied an integrative approach using DNA barcoding and traditional morphology-based bioassessment to identify fish from a neotropical region possessing low taxonomic knowledge: the Jequitinhonha River Basin (Southeastern Brazil). The Jequitinhonha River Basin (JRB) has a high rate of endemism and is considered an area of high priority for fish conservation, with estimates indicating the presence of around 110 native and non-indigenous species. DNA barcodes were obtained from 260 individuals belonging to 52 species distributed among 35 genera, 21 families and 6 orders, including threatened and rare species such as Rhamdia jequitinhonha and Steindachneridion amblyurum. The mean Kimura two-parameter genetic distances within species, genera and families were: 0.44, 12.16 and 20.58 %, respectively. Mean intraspecific genetic variation ranged from 0 to 11.43 %, and high values (>2 %) were recovered for five species. Species with a deep intraspecific distance, possibly flagging overlooked taxa, were detected within the genus Pimelodella. Fifteen species, only identified to the genus level, had unique BINs, with a nearest neighbor distance over 2 % and therefore, potential new candidate species supported by DNA barcoding. The integrative taxonomy approach using DNA barcoding and traditional taxonomy may be a remedy to taxonomy impediment, accelerating species identification by flagging potential new candidate species and to adequately conserve the megadiverse neotropical ichthyofauna.

Percent Forest Adjacent to Streams

Data.gov (United States)

U.S. Environmental Protection Agency — The type of vegetation along a stream influences the water quality in the stream. Intact buffer strips of natural vegetation along streams tend to intercept...

Percent Agriculture Adjacent to Streams

Data.gov (United States)

U.S. Environmental Protection Agency — The type of vegetation along a stream influences the water quality in the stream. Intact buffer strips of natural vegetation along streams tend to intercept...

Morphology of a Wetland Stream

Science.gov (United States)

Jurmu; Andrle

1997-11-01

/ Little attention has been paid to wetland stream morphology in the geomorphological and environmental literature, and in the recently expanding wetland reconstruction field, stream design has been based primarily on stream morphologies typical of nonwetland alluvial environments. Field investigation of a wetland reach of Roaring Brook, Stafford, Connecticut, USA, revealed several significant differences between the morphology of this stream and the typical morphology of nonwetland alluvial streams. Six morphological features of the study reach were examined: bankfull flow, meanders, pools and riffles, thalweg location, straight reaches, and cross-sectional shape. It was found that bankfull flow definitions originating from streams in nonwetland environments did not apply. Unusual features observed in the wetland reach include tight bends and a large axial wavelength to width ratio. A lengthy straight reach exists that exceeds what is typically found in nonwetland alluvial streams. The lack of convex bank point bars in the bends, a greater channel width at riffle locations, an unusual thalweg location, and small form ratios (a deep and narrow channel) were also differences identified. Further study is needed on wetland streams of various regions to determine if differences in morphology between alluvial and wetland environments can be applied in order to improve future designs of wetland channels.KEY WORDS: Stream morphology; Wetland restoration; Wetland creation; Bankfull; Pools and riffles; Meanders; Thalweg

Dynamical modeling of tidal streams

International Nuclear Information System (INIS)

Bovy, Jo

2014-01-01

I present a new framework for modeling the dynamics of tidal streams. The framework consists of simple models for the initial action-angle distribution of tidal debris, which can be straightforwardly evolved forward in time. Taking advantage of the essentially one-dimensional nature of tidal streams, the transformation to position-velocity coordinates can be linearized and interpolated near a small number of points along the stream, thus allowing for efficient computations of a stream's properties in observable quantities. I illustrate how to calculate the stream's average location (its 'track') in different coordinate systems, how to quickly estimate the dispersion around its track, and how to draw mock stream data. As a generative model, this framework allows one to compute the full probability distribution function and marginalize over or condition it on certain phase-space dimensions as well as convolve it with observational uncertainties. This will be instrumental in proper data analysis of stream data. In addition to providing a computationally efficient practical tool for modeling the dynamics of tidal streams, the action-angle nature of the framework helps elucidate how the observed width of the stream relates to the velocity dispersion or mass of the progenitor, and how the progenitors of 'orphan' streams could be located. The practical usefulness of the proposed framework crucially depends on the ability to calculate action-angle variables for any orbit in any gravitational potential. A novel method for calculating actions, frequencies, and angles in any static potential using a single orbit integration is described in the Appendix.

Human impacts to mountain streams

Science.gov (United States)

Wohl, Ellen

2006-09-01

Mountain streams are here defined as channel networks within mountainous regions of the world. This definition encompasses tremendous diversity of physical and biological conditions, as well as history of land use. Human effects on mountain streams may result from activities undertaken within the stream channel that directly alter channel geometry, the dynamics of water and sediment movement, contaminants in the stream, or aquatic and riparian communities. Examples include channelization, construction of grade-control structures or check dams, removal of beavers, and placer mining. Human effects can also result from activities within the watershed that indirectly affect streams by altering the movement of water, sediment, and contaminants into the channel. Deforestation, cropping, grazing, land drainage, and urbanization are among the land uses that indirectly alter stream processes. An overview of the relative intensity of human impacts to mountain streams is provided by a table summarizing human effects on each of the major mountainous regions with respect to five categories: flow regulation, biotic integrity, water pollution, channel alteration, and land use. This table indicates that very few mountains have streams not at least moderately affected by land use. The least affected mountainous regions are those at very high or very low latitudes, although our scientific ignorance of conditions in low-latitude mountains in particular means that streams in these mountains might be more altered than is widely recognized. Four case studies from northern Sweden (arctic region), Colorado Front Range (semiarid temperate region), Swiss Alps (humid temperate region), and Papua New Guinea (humid tropics) are also used to explore in detail the history and effects on rivers of human activities in mountainous regions. The overview and case studies indicate that mountain streams must be managed with particular attention to upstream/downstream connections, hillslope

Investigation of helium plasma stream parameters in experiments on surface modification

International Nuclear Information System (INIS)

Bandura, A.N.; Byrka, O.V.; Chebotarev, V.V.; Garkusha, I.E.; Tsarenko, A.V. and eds.

2005-01-01

The main objection of this study is adjustment of plasma treatment regimes for different materials that allows achieving optimal thickness of modified layer with simultaneously minimal value of surface roughness. With use of optical spectroscopy, detailed information about the basic plasma parameters - electron density, electron and ion temperatures, plasma stream duration and velocity, was obtained. Integrated spectra of plasma radiation were analyzed. The majority of helium and impurity spectral lines were investigated on a subject of Stark broadening. Plasma pressure and energy density values measured with piezodetectors and calorimeters are in good agreement with plasma parameters obtained by optical techniques

How and Why Does Stream Water Temperature Vary at Small Spatial Scales in a Headwater Stream?

Science.gov (United States)

Morgan, J. C.; Gannon, J. P.; Kelleher, C.

2017-12-01

The temperature of stream water is controlled by climatic variables, runoff/baseflow generation, and hyporheic exchange. Hydrologic conditions such as gaining/losing reaches and sources of inflow can vary dramatically along a stream on a small spatial scale. In this work, we attempt to discern the extent that the factors of air temperature, groundwater inflow, and precipitation influence stream temperature at small spatial scales along the length of a stream. To address this question, we measured stream temperature along the perennial stream network in a 43 ha catchment with a complex land use history in Cullowhee, NC. Two water temperature sensors were placed along the stream network on opposite sides of the stream at 100-meter intervals and at several locations of interest (i.e. stream junctions). The forty total sensors recorded the temperature every 10 minutes for one month in the spring and one month in the summer. A subset of sampling locations where stream temperature was consistent or varied from one side of the stream to the other were explored with a thermal imaging camera to obtain a more detailed representation of the spatial variation in temperature at those sites. These thermal surveys were compared with descriptions of the contributing area at the sample sites in an effort to discern specific causes of differing flow paths. Preliminary results suggest that on some branches of the stream stormflow has less influence than regular hyporheic exchange, while other tributaries can change dramatically with stormflow conditions. We anticipate this work will lead to a better understanding of temperature patterns in stream water networks. A better understanding of the importance of small-scale differences in flow paths to water temperature may be able to inform watershed management decisions in the future.

Stream Deniable-Encryption Algorithms

Directory of Open Access Journals (Sweden)

N.A. Moldovyan

2016-04-01

Full Text Available A method for stream deniable encryption of secret message is proposed, which is computationally indistinguishable from the probabilistic encryption of some fake message. The method uses generation of two key streams with some secure block cipher. One of the key streams is generated depending on the secret key and the other one is generated depending on the fake key. The key streams are mixed with the secret and fake data streams so that the output ciphertext looks like the ciphertext produced by some probabilistic encryption algorithm applied to the fake message, while using the fake key. When the receiver or/and sender of the ciphertext are coerced to open the encryption key and the source message, they open the fake key and the fake message. To disclose their lie the coercer should demonstrate possibility of the alternative decryption of the ciphertext, however this is a computationally hard problem.

CAMS: OLAPing Multidimensional Data Streams Efficiently

Science.gov (United States)

Cuzzocrea, Alfredo

In the context of data stream research, taming the multidimensionality of real-life data streams in order to efficiently support OLAP analysis/mining tasks is a critical challenge. Inspired by this fundamental motivation, in this paper we introduce CAMS (C ube-based A cquisition model for M ultidimensional S treams), a model for efficiently OLAPing multidimensional data streams. CAMS combines a set of data stream processing methodologies, namely (i) the OLAP dimension flattening process, which allows us to obtain dimensionality reduction of multidimensional data streams, and (ii) the OLAP stream aggregation scheme, which aggregates data stream readings according to an OLAP-hierarchy-based membership approach. We complete our analytical contribution by means of experimental assessment and analysis of both the efficiency and the scalability of OLAPing capabilities of CAMS on synthetic multidimensional data streams. Both analytical and experimental results clearly connote CAMS as an enabling component for next-generation Data Stream Management Systems.

On the sensitivity evaluation for on-stream elemental analysis using neutron and photoactivation techniques

International Nuclear Information System (INIS)

Ivanov, I.N.; Zakharov, E.A.; Kasatkin, V.A.; Kartashev, E.R.; Mashinin, V.A.; Feoktistov, Yu.V.; Tchulkin, V.L.

1984-01-01

The paper discusses the data of calculations of neutron and photonactivation effects of moving substances, in particular, bulk materials moving on a conveyor belt and solution streams. The calculated data on minimum detectable concentrations of the various elements are given. The calculation data satisfactorily agree with the experimental data obtained as a result of on-stream neutron activation analysis of solutions containing indium, selenium, aluminium, fluorine and also bulk materials containing aluminium and silicon. The opportunity of applying the bremsstrahlung generated by the electron accelerator for photon activation analysis and sorting gold-bearing ores on the conveyor belt has been analysed

Revision of the Neotropical genus Protoconnus Franz (Coleoptera: Staphylinidae: Scydmaeninae).

Science.gov (United States)

JaŁoszyŃski, PaweŁ

2018-03-07

The Neotropical genus Protoconnus Franz, belonging to the tribe Glandulariini, is revised. Protoconnus is redefined based on detailed morphological study, and all known species are revised, including 10 originally placed in Protoconnus, one transferred from Euconnus, and 14 described as new. The following species are treated: P. andicola Franz (Peru), P. peruensis Franz (Peru), P. minutus Franz (Peru), P. minutissimus Franz (Peru), P. venezolanus Franz (Venezuela), P. araguanus Franz (Venezuela), P. bolivianus Franz (Bolivia), P. comarapae Franz (Bolivia), P. robustus Franz (Bolivia), P. paraguayanus Franz (Paraguay), P. princeps (Franz), comb. n. (ex Euconnus) (Peru), P. quillabambanus sp. n. (Peru), P. ecuadoranus sp. n. (Ecuador), P. napoanus sp. n. (Ecuador), P. magnus sp. n. (Ecuador), P. impressifrons sp. n. (Bolivia), P. angustus sp. n. (Bolivia), P. acutus sp. n. (Bolivia), P. tunarianus sp. n. (Bolivia), P. apaapa sp. n. (Bolivia), P. maximus sp. n. (Costa Rica), P. minusculus sp. n. (Costa Rica), P. costaricanus sp. n. (Costa Rica), P. inexpectatus sp. n. (Costa Rica), and P. volcanbaru sp. n. (Panama). Lectotypes are designated for P. andicola and P. peruensis.

Canopy area of large trees explains aboveground biomass variations across neotropical forest landscapes

Science.gov (United States)

Meyer, Victoria; Saatchi, Sassan; Clark, David B.; Keller, Michael; Vincent, Grégoire; Ferraz, António; Espírito-Santo, Fernando; d'Oliveira, Marcus V. N.; Kaki, Dahlia; Chave, Jérôme

2018-06-01

Large tropical trees store significant amounts of carbon in woody components and their distribution plays an important role in forest carbon stocks and dynamics. Here, we explore the properties of a new lidar-derived index, the large tree canopy area (LCA) defined as the area occupied by canopy above a reference height. We hypothesize that this simple measure of forest structure representing the crown area of large canopy trees could consistently explain the landscape variations in forest volume and aboveground biomass (AGB) across a range of climate and edaphic conditions. To test this hypothesis, we assembled a unique dataset of high-resolution airborne light detection and ranging (lidar) and ground inventory data in nine undisturbed old-growth Neotropical forests, of which four had plots large enough (1 ha) to calibrate our model. We found that the LCA for trees greater than 27 m (˜ 25-30 m) in height and at least 100 m2 crown size in a unit area (1 ha), explains more than 75 % of total forest volume variations, irrespective of the forest biogeographic conditions. When weighted by average wood density of the stand, LCA can be used as an unbiased estimator of AGB across sites (R2 = 0.78, RMSE = 46.02 Mg ha-1, bias = -0.63 Mg ha-1). Unlike other lidar-derived metrics with complex nonlinear relations to biomass, the relationship between LCA and AGB is linear and remains unique across forest types. A comparison with tree inventories across the study sites indicates that LCA correlates best with the crown area (or basal area) of trees with diameter greater than 50 cm. The spatial invariance of the LCA-AGB relationship across the Neotropics suggests a remarkable regularity of forest structure across the landscape and a new technique for systematic monitoring of large trees for their contribution to AGB and changes associated with selective logging, tree mortality and other types of tropical forest disturbance and dynamics.

Comparing hair-morphology and molecular methods to identify fecal samples from Neotropical felids.

Directory of Open Access Journals (Sweden)

Carlos C Alberts

Full Text Available To avoid certain problems encountered with more-traditional and invasive methods in behavioral-ecology studies of mammalian predators, such as felids, molecular approaches have been employed to identify feces found in the field. However, this method requires a complete molecular biology laboratory, and usually also requires very fresh fecal samples to avoid DNA degradation. Both conditions are normally absent in the field. To address these difficulties, identification based on morphological characters (length, color, banding, scales and medullar patterns of hairs found in feces could be employed as an alternative. In this study we constructed a morphological identification key for guard hairs of eight Neotropical felids (jaguar, oncilla, Geoffroy's cat, margay, ocelot, Pampas cat, puma and jaguarundi and compared its efficiency to that of a molecular identification method, using the ATP6 region as a marker. For this molecular approach, we simulated some field conditions by postponing sample-conservation procedures. A blind test of the identification key obtained a nearly 70% overall success rate, which we considered equivalent to or better than the results of some molecular methods (probably due to DNA degradation found in other studies. The jaguar, puma and jaguarundi could be unequivocally discriminated from any other Neotropical felid. On a scale ranging from inadequate to excellent, the key proved poor only for the margay, with only 30% of its hairs successfully identified using this key; and have intermediate success rates for the remaining species, the oncilla, Geoffroy's cat, ocelot and Pampas cat, were intermediate. Complementary information about the known distributions of felid populations may be necessary to substantially improve the results obtained with the key. Our own molecular results were even better, since all blind-tested samples were correctly identified. Part of these identifications were made from samples kept in suboptimal

Nuclear DNA content in 20 species of Siluriformes (Teleostei: Ostariophysi from the Neotropical region

Directory of Open Access Journals (Sweden)

Paulo César Fenerich

2004-01-01

Full Text Available In the present study, 20 species of Siluriformes fish were analyzed in order to determine their nuclear DNA content and compare these data with their diploid number. In addition, the extension and importance of the changes that occurred during the process of diversification in the group of Neotropical freshwater catfish were investigated. The only species studied of the family Doradidae, Rhinodoras d'orbignyi (2n = 58, presented 3.46 ± 0.13 pg of DNA. Among the species of the family Heptapteridae, the values of nuclear DNA content and the diploid numbers ranged from 1.13 ± 0.09 pg of DNA in Pimelodella sp. (2n = 46 to 2.38 ± 0.07 pg of DNA in Imparfinis mirini (2n = 58. The family Loricariidae showed the widest variation in diploid number and nuclear DNA content values, ranging from 2n = 52 and 3.96 ± 0.22 pg of DNA in Liposarcus anisitsi to 2n = 76 and 4.90 ± 0.12 pg of DNA in Hypostomus sp. 4. In this group, two local samples of Pimelodus maculatus (Pimelodidae were analyzed, and both exhibited 2n = 56, but different nuclear DNA content values (2.68 ± 0.22 pg and 2.82 ± 0.20 pg, respectively. Among the Pseudopimelodidae species analyzed, Pseudopimelodus mangurus (2n = 54 showed 2.23 ± 0.15 pg and Microglanis cottoides (2n = 54 exhibited 2.50 ± 0.18 pg of DNA. Two species of Trichomycterus (Trichomycteridae also presented the same diploid number, 2n = 54 chromosomes, but, while the species from the Quinta stream presented a DNA content of 2.62 ± 0.19 pg, in the sample from the Capivara river this value was 2.30 ± 0.23 pg. In the analyzed species, the results showed that the changes in DNA content were frequently not followed by changes in the diploid number. This fact permits to suggest that, in addition to structural chromosome rearrangements, other mechanisms, including deletions, duplications and polyploidy, could be involved in the process of species differentiation in the representatives of the fish order Siluriformes.

Three-dimensional model of corotating streams in the solar wind 3. Magnetohydrodynamic streams

International Nuclear Information System (INIS)

Pizzo, V.J.

1982-01-01

The focus of this paper is two-fold: (1) to examine how the presence of the spiral magnetic field affects the evolution of interplanetary corotating solar wind streams, and (2) to ascertain the nature of secondary large-scale phenomena likely to be associated with streams having a pronounced three-dimensional (3-D) structure. The dynamics are presumed to be governed by the nonlinear polytropic, single-fluid, 3-D MHD equations. Solutions are obtained with an explicit, Eulerian, finite differences technique that makes use of a simple form of artificial diffusion for handling shocks. For smooth axisymmetric flows, the picture of magnetically induced meridional motions previously established by linear models requires only minor correction. In the case of broad 3-D streams input near the sun, inclusion of the magnetic field is found to retard the kinematic steepening at the stream front substantially but to produce little deviation from planar flow. For the more realistic case of initially sharply bounded streams, however, it becomes essential to account for magnetic effects in the formulation. Whether a full 3-D treatment is required depends upon the latitudinal geometry of the stream

Cytoplasmic Streaming in the Drosophila Oocyte.

Science.gov (United States)

Quinlan, Margot E

2016-10-06

Objects are commonly moved within the cell by either passive diffusion or active directed transport. A third possibility is advection, in which objects within the cytoplasm are moved with the flow of the cytoplasm. Bulk movement of the cytoplasm, or streaming, as required for advection, is more common in large cells than in small cells. For example, streaming is observed in elongated plant cells and the oocytes of several species. In the Drosophila oocyte, two stages of streaming are observed: relatively slow streaming during mid-oogenesis and streaming that is approximately ten times faster during late oogenesis. These flows are implicated in two processes: polarity establishment and mixing. In this review, I discuss the underlying mechanism of streaming, how slow and fast streaming are differentiated, and what we know about the physiological roles of the two types of streaming.

In-stream Physical Heterogeneity, Rainfall Aided Flushing, and Discharge on Stream Water Quality.

Science.gov (United States)

Gomes, Pattiyage I A; Wai, Onyx W H

2015-08-01

Implications of instream physical heterogeneity, rainfall-aided flushing, and stream discharge on water quality control have been investigated in a headwater stream of a climatic region that has contrasting dry and wet seasons. Dry (low flow) season's physical heterogeneity showed a positive correlation with good water quality. However, in the wet season, physical heterogeneity showed minor or no significance on water quality variations. Furthermore, physical heterogeneity appeared to be more complementary with good water quality subsequent to rainfall events. In many cases stream discharge was a reason for poor water quality. For the dry season, graywater inputs to the stream could be held responsible. In the wet season, it was probably the result of catchment level disturbances (e.g., regulation of ephemeral freshwater paths). Overall, this study revealed the importance of catchment-based approaches on water quality improvement in tandem with in-stream approaches framed on a temporal scale.

Stream II-V5: Revision Of Stream II-V4 To Account For The Effects Of Rainfall Events

International Nuclear Information System (INIS)

Chen, K.

2010-01-01

STREAM II-V4 is the aqueous transport module currently used by the Savannah River Site emergency response Weather Information Display (WIND) system. The transport model of the Water Quality Analysis Simulation Program (WASP) was used by STREAM II to perform contaminant transport calculations. WASP5 is a US Environmental Protection Agency (EPA) water quality analysis program that simulates contaminant transport and fate through surface water. STREAM II-V4 predicts peak concentration and peak concentration arrival time at downstream locations for releases from the SRS facilities to the Savannah River. The input flows for STREAM II-V4 are derived from the historical flow records measured by the United States Geological Survey (USGS). The stream flow for STREAM II-V4 is fixed and the flow only varies with the month in which the releases are taking place. Therefore, the effects of flow surge due to a severe storm are not accounted for by STREAM II-V4. STREAM II-V4 has been revised to account for the effects of a storm event. The steps used in this method are: (1) generate rainfall hyetographs as a function of total rainfall in inches (or millimeters) and rainfall duration in hours; (2) generate watershed runoff flow based on the rainfall hyetographs from step 1; (3) calculate the variation of stream segment volume (cross section) as a function of flow from step 2; (4) implement the results from steps 2 and 3 into the STREAM II model. The revised model (STREAM II-V5) will find the proper stream inlet flow based on the total rainfall and rainfall duration as input by the user. STREAM II-V5 adjusts the stream segment volumes (cross sections) based on the stream inlet flow. The rainfall based stream flow and the adjusted stream segment volumes are then used for contaminant transport calculations.

Review of Cyrtomyia Bigot (Diptera, BomByliidae, Ecliminae with a key to the Neotropical genera of Ecliminae and Cyrtomyia species

Directory of Open Access Journals (Sweden)

Carlos José Einicker Lamas

2013-01-01

Full Text Available The Neotropical genus Cyrtomyia Bigot has a distribution restricted to the Andean region of South America, with records only in Argentina and Chile. The genus is composed by two species, which are reviewed and redescribed herein: C. chilensis Paramonov, 1931 and C. pictipennis (Bigot, 1857. The main characters of the external morphology of adults are photographed. Illustrations of the male and female terminalia of C. chilensis are also included. An identification key to species is presented, and the species distribution is briefly discussed.O gênero Neotropical Cyrtomyia Bigot tem uma distribuição restrita à região Andina da América do Sul, com registros assinalados apenas para a Argentina e Chile. O gênero é composto por duas espécies, que são aqui revisadas e redescritas: C. chilensis Paramonov, 1931 e C. pictipennis (Bigot, 1857. Os principais caracteres da morfologia externa dos adultos estão fotografados. Ilustrações das terminálias de machos e de fêmeas de C. chilensis também são incluídas. Uma chave de identificação para as espécies é apresentada e a distribuição das espécies é brevemente discutida.

Stream Clustering of Growing Objects

Science.gov (United States)

Siddiqui, Zaigham Faraz; Spiliopoulou, Myra

We study incremental clustering of objects that grow and accumulate over time. The objects come from a multi-table stream e.g. streams of Customer and Transaction. As the Transactions stream accumulates, the Customers’ profiles grow. First, we use an incremental propositionalisation to convert the multi-table stream into a single-table stream upon which we apply clustering. For this purpose, we develop an online version of K-Means algorithm that can handle these swelling objects and any new objects that arrive. The algorithm also monitors the quality of the model and performs re-clustering when it deteriorates. We evaluate our method on the PKDD Challenge 1999 dataset.

LHCb trigger streams optimization

Science.gov (United States)

Derkach, D.; Kazeev, N.; Neychev, R.; Panin, A.; Trofimov, I.; Ustyuzhanin, A.; Vesterinen, M.

2017-10-01

The LHCb experiment stores around 1011 collision events per year. A typical physics analysis deals with a final sample of up to 107 events. Event preselection algorithms (lines) are used for data reduction. Since the data are stored in a format that requires sequential access, the lines are grouped into several output file streams, in order to increase the efficiency of user analysis jobs that read these data. The scheme efficiency heavily depends on the stream composition. By putting similar lines together and balancing the stream sizes it is possible to reduce the overhead. We present a method for finding an optimal stream composition. The method is applied to a part of the LHCb data (Turbo stream) on the stage where it is prepared for user physics analysis. This results in an expected improvement of 15% in the speed of user analysis jobs, and will be applied on data to be recorded in 2017.

The ventral stream offers more affordance and the dorsal stream more memory than believed

NARCIS (Netherlands)

Postma, Albert; van der Lubbe, Robert Henricus Johannes; Zuidhoek, Sander

2002-01-01

Opposed to Norman's proposal, processing of affordance is likely to occur not solely in the dorsal stream but also in the ventral stream. Moreover, the dorsal stream might do more than just serve an important role in motor actions. It supports egocentric location coding as well. As such, it would

The role of remediation, natural alkalinity sources and physical stream parameters in stream recovery.

Science.gov (United States)

Kruse, Natalie A; DeRose, Lisa; Korenowsky, Rebekah; Bowman, Jennifer R; Lopez, Dina; Johnson, Kelly; Rankin, Edward

2013-10-15

Acid mine drainage (AMD) negatively impacts not only stream chemistry, but also aquatic biology. The ultimate goal of AMD treatment is restoration of the biological community, but that goal is rarely explicit in treatment system design. Hewett Fork in Raccoon Creek Watershed, Ohio, has been impacted by historic coal mining and has been treated with a calcium oxide doser in the headwaters of the watershed since 2004. All of the acidic inputs are isolated to a 1.5 km stretch of stream in the headwaters of the Hewett Fork watershed. The macroinvertebrate and fish communities have begun to recover and it is possible to distinguish three zones downstream of the doser: an impaired zone, a transition zone and a recovered zone. Alkalinity from both the doser and natural sources and physical stream parameters play a role in stream restoration. In Hewett Fork, natural alkaline additions downstream are higher than those from the doser. Both, alkaline additions and stream velocity drive sediment and metal deposition. Metal deposition occurs in several patterns; aluminum tends to deposit in regions of low stream velocity, while iron tends to deposit once sufficient alkalinity is added to the system downstream of mining inputs. The majority of metal deposition occurs upstream of the recovered zone. Both the physical stream parameters and natural alkalinity sources influence biological recovery in treated AMD streams and should be considered in remediation plans. Copyright © 2013 Elsevier Ltd. All rights reserved.

Continental-scale patterns and climatic drivers of fruiting phenology: A quantitative Neotropical review

Science.gov (United States)

Mendoza, Irene; Peres, Carlos A.; Morellato, Leonor Patrícia C.

2017-01-01

Changes in the life cycle of organisms (i.e. phenology) are one of the most widely used early-warning indicators of climate change, yet this remains poorly understood throughout the tropics. We exhaustively reviewed any published and unpublished study on fruiting phenology carried out at the community level in the American tropics and subtropics (latitudinal range: 26°N-26°S) to (1) provide a comprehensive overview of the current status of fruiting phenology research throughout the Neotropics; (2) unravel the climatic factors that have been widely reported as drivers of fruiting phenology; and (3) provide a preliminary assessment of the potential phenological responses of plants under future climatic scenarios. Despite the large number of phenological datasets uncovered (218), our review shows that their geographic distribution is very uneven and insufficient for the large surface of the Neotropics ( 1 dataset per 78,000 km2). Phenological research is concentrated in few areas with many studies (state of São Paulo, Brazil, and Costa Rica), whereas vast regions elsewhere are entirely unstudied. Sampling effort in fruiting phenology studies was generally low: the majority of datasets targeted fewer than 100 plant species (71%), lasted 2 years or less (72%), and only 10.4% monitored > 15 individuals per species. We uncovered only 10 sites with ten or more years of phenological monitoring. The ratio of numbers of species sampled to overall estimates of plant species richness was wholly insufficient for highly diverse vegetation types such as tropical rainforest, seasonal forest and cerrado, and only slightly more robust for less diverse vegetation types, such as deserts, arid shrublands and open grassy savannas. Most plausible drivers of phenology extracted from these datasets were environmental (78.5%), whereas biotic drivers were rare (6%). Among climatic factors, rainfall was explicitly included in 73.4% of cases, followed by air temperature (19.3%). Other

Relevance of southward magnetic fields in the neutral sheet to anisotropic distribution of energetic electrons and substorm activity

International Nuclear Information System (INIS)

Lui, A.T.Y.; Meng, C.

1979-01-01

The implications of southward magnetic fields at the magnetotail neutral sheet to the development of streaming anisotropy of energetic electrons and magnetospheric substorm activity are examined. Magnetic field and energetic particle measurements from the Imp 6 spacecraft, the AE index, and global auroral images from DMSP spacecraft are utilized in this study. Criteria are developed to identify events of southward magnetic fields at the neutral sheet which imply the presence of X-type magnetic neutral lines. Several features of the observations suggest that the southward magnetic fields and the implied X-type neutral lines are associated with magnetic bubbles in the neutral sheet region. It is found that the signatures of magnetic bubbles are sometimes detected in association with tailward streaming and flux enhancement of energetic electrons (47 keV< E<350keV). A cigar-shaped anisotropy in the energetic electron distribution is frequently but not always observed before the onset of tailward streaming of energetic electrons. The tailward streaming is magnetic field-aligned and occurs in the form of bursts, suggestic electrons. The tailward streaming is magnetic field-aligned and occurs in the form of bursts, suggesting that the generating process is activated somewhat quasi-periodically and is not in a steady state. Signatures of magnetic bubbles are also detected without any substantial enhancement or detectable tailward streaming of energetic electrons. By comparing Imp 6 observations with the AW index and global auroral images from DMSP spacecraft. It is found that signatures of magnetic bubbles in the neutral sheet are observed during substorms as well as during quiet geomagnetic conditions, indicating that magnetic bubbles are intrinsic features of the neutral sheet in the magnetotail regardless of substorm activity

The long term response of stream flow to climatic warming in headwater streams of interior Alaska

Science.gov (United States)

Jeremy B. Jones; Amanda J. Rinehart

2010-01-01

Warming in the boreal forest of interior Alaska will have fundamental impacts on stream ecosystems through changes in stream hydrology resulting from upslope loss of permafrost, alteration of availability of soil moisture, and the distribution of vegetation. We examined stream flow in three headwater streams of the Caribou-Poker Creeks Research Watershed (CPCRW) in...

Sobre um novo gênero neotrópico da subfamília Tanypodinae (Diptera, Chironomidae On a new neotropical genus of the subfamily Tanypodinae (Diptera, Chironomidae

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Sebastião José de Oliveira

1992-01-01

Full Text Available A new neotropical genus and a new species of a non-biting midge for the subfamily Tanypodinae from Brazil are described. The new genus is near Tanypus Meigen, 1803 and Procladius Skuse, 1889, but differs of both by wings and male terminalia.

The Stream-Catchment (StreamCat) Dataset: A database of watershed metrics for the conterminous USA

Science.gov (United States)

We developed an extensive database of landscape metrics for ~2.65 million streams, and their associated catchments, within the conterminous USA: The Stream-Catchment (StreamCat) Dataset. These data are publically available and greatly reduce the specialized geospatial expertise n...

Is the Karyotype of Neotropical Boid Snakes Really Conserved? Cytotaxonomy, Chromosomal Rearrangements and Karyotype Organization in the Boidae Family.

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Patrik F Viana

Full Text Available Boids are primitive snakes from a basal lineage that is widely distributed in Neotropical region. Many of these species are both morphologically and biogeographically divergent, and the relationship among some species remains uncertain even with evolutionary and phylogenetic studies being proposed for the group. For a better understanding of the evolutionary relationship between these snakes, we cytogenetically analysed 7 species and 3 subspecies of Neotropical snakes from the Boidae family using different chromosomal markers. The karyotypes of Boa constrictor occidentalis, Corallus hortulanus, Eunectes notaeus, Epicrates cenchria and Epicrates assisi are presented here for the first time with the redescriptions of the karyotypes of Boa constrictor constrictor, B. c. amarali, Eunectes murinus and Epicrates crassus. The three subspecies of Boa, two species of Eunectes and three species of Epicrates exhibit 2n = 36 chromosomes. In contrast, C. hortulanus presented a totally different karyotype composition for the Boidae family, showing 2n = 40 chromosomes with a greater number of macrochromosomes. Furthermore, chromosomal mapping of telomeric sequences revealed the presence of interstitial telomeric sites (ITSs on many chromosomes in addition to the terminal markings on all chromosomes of all taxa analysed, with the exception of E. notaeus. Thus, we demonstrate that the karyotypes of these snakes are not as highly conserved as previously thought. Moreover, we provide an overview of the current cytotaxonomy of the group.

Testing aggregation hypotheses among Neotropical trees and shrubs: results from a 50-ha plot over 20 years of sampling.

Science.gov (United States)

Myster, Randall W; Malahy, Michael P

2012-09-01

Spatial patterns of tropical trees and shrubs are important to understanding their interaction and the resultant structure of tropical rainforests. To assess this issue, we took advantage of previously collected data, on Neotropical tree and shrub stem identified to species and mapped for spatial coordinates in a 50ha plot, with a frequency of every five years and over a 20 year period. These stems data were first placed into four groups, regardless of species, depending on their location in the vertical strata of the rainforest (shrubs, understory trees, mid-sized trees, tall trees) and then used to generate aggregation patterns for each sampling year. We found shrubs and understory trees clumped at small spatial scales of a few meters for several of the years sampled. Alternatively, mid-sized trees and tall trees did not clump, nor did they show uniform (regular) patterns, during any sampling period. In general (1) groups found higher in the canopy did not show aggregation on the ground and (2) the spatial patterns of all four groups showed similarity among different sampling years, thereby supporting a "shifting mosaic" view of plant communities over large areas. Spatial analysis, such as this one, are critical to understanding and predicting tree spaces, tree-tree replacements and the Neotropical forest patterns, such as biodiversity and those needed for sustainability efforts, they produce.

Stream processing health card application.

Science.gov (United States)

Polat, Seda; Gündem, Taflan Imre

2012-10-01

In this paper, we propose a data stream management system embedded to a smart card for handling and storing user specific summaries of streaming data coming from medical sensor measurements and/or other medical measurements. The data stream management system that we propose for a health card can handle the stream data rates of commonly known medical devices and sensors. It incorporates a type of context awareness feature that acts according to user specific information. The proposed system is cheap and provides security for private data by enhancing the capabilities of smart health cards. The stream data management system is tested on a real smart card using both synthetic and real data.

Leaf litter processing in West Virginia mountain streams: effects of temperature and stream chemistry

Science.gov (United States)

Jacquelyn M. Rowe; William B. Perry; Sue A. Perry

1996-01-01

Climate change has the potential to alter detrital processing in headwater streams, which receive the majority of their nutrient input as terrestrial leaf litter. Early placement of experimental leaf packs in streams, one month prior to most abscission, was used as an experimental manipulation to increase stream temperature during leaf pack breakdown. We studied leaf...

Stream invertebrate productivity linked to forest subsidies: 37 stream-years of reference and experimental data.

Science.gov (United States)

Wallace, J Bruce; Eggert, Susan L; Meyer, Judy L; Webster, Jackson R

2015-05-01

Riparian habitats provide detrital subsidies of varying quantities and qualities to recipient ecosystems. We used long-term data from three reference streams (covering 24 stream-years) and 13-year whole-stream organic matter manipulations to investigate the influence of terrestrial detrital quantity and quality on benthic invertebrate community structure, abundance, biomass, and secondary production in rockface (RF) and mixed substrates (MS) of forested headwater streams. Using a mesh canopy covering the entire treatment stream, we examined effects of litter ex'clusion, small- and large-wood removal, and addition of artificial wood (PVC) and leaves of varying quality on organic matter standing crops and invertebrate community structure and function. We assessed differences in functional feeding group distribution between substrate types as influenced by organic matter manipulations and long-term patterns of predator and prey production in manipulated vs. reference years. Particulate organic matter standing crops in MS of the treatment stream declined drastically with each successive year of litter exclusion, approaching zero after three years. Monthly invertebrate biomass and annual secondary production was positively related to benthic organic matter in the MS habitats. Rockface habitats exhibited fewer changes than MS habitats across all organic matter manipulations. With leaf addition, the patterns of functional group distribution among MS and RF habitats returned to patterns seen in reference streams. Secondary production per unit organic matter standing crop was greatest for the leaf addition period, followed by the reference streams, and significantly less for the litter exclusion and wood removal periods. These data indicate that the limited organic matter remaining in the stream following litter exclusion and wood removal was more refractory than that in the reference streams, whereas the added leaf material was more labile and readily converted into

Generation of electronic waste in India: Current scenario, dilemmas ...

African Journals Online (AJOL)

This paper tries to quantify the amount of E-waste generated in India with the related stakeholder involvement. Electronic waste (E-waste) or waste electrical and electronic equipments (WEEE), which is relatively a recent addition to the hazardous waste stream, is drawing rapid attention across the globe as the quantity ...

Fast acoustic streaming in standing waves: generation of an additional outer streaming cell.

Science.gov (United States)

Reyt, Ida; Daru, Virginie; Bailliet, Hélène; Moreau, Solène; Valière, Jean-Christophe; Baltean-Carlès, Diana; Weisman, Catherine

2013-09-01

Rayleigh streaming in a cylindrical acoustic standing waveguide is studied both experimentally and numerically for nonlinear Reynolds numbers from 1 to 30 [Re(NL)=(U0/c0)(2)(R/δν)(2), with U0 the acoustic velocity amplitude at the velocity antinode, c0 the speed of sound, R the tube radius, and δν the acoustic boundary layer thickness]. Streaming velocity is measured by means of laser Doppler velocimetry in a cylindrical resonator filled with air at atmospheric pressure at high intensity sound levels. The compressible Navier-Stokes equations are solved numerically with high resolution finite difference schemes. The resonator is excited by shaking it along the axis at imposed frequency. Results of measurements and of numerical calculation are compared with results given in the literature and with each other. As expected, the axial streaming velocity measured and calculated agrees reasonably well with the slow streaming theory for small ReNL but deviates significantly from such predictions for fast streaming (ReNL>1). Both experimental and numerical results show that when ReNL is increased, the center of the outer streaming cells are pushed toward the acoustic velocity nodes until counter-rotating additional vortices are generated near the acoustic velocity antinodes.

Ulcerative and granulomatous enteritis associated with Molineus torulosus parasitism in neotropical primates

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Max Bruno Magno Bacalhao

Full Text Available ABSTRACT: This paper reports eleven cases of ulcerative and granulomatous enteritis associated with Molineus torulosus parasitism in different species of neotropical primates of the Sapajus genus. All of the affected monkeys had been apprehended by the environmental police and were being treated in a rehabilitation center for wild animals. The clinical history was weight loss and debility. During the necropsy, several nodules were found on the duodenum and proximal jejunum wall, with ulcers on the adjacent intestinal mucosa, including the nodules in the pancreas of four monkeys. Histologically, eosinophilic granulomas were observed in the small intestine, associated with fibrosis, eggs and adult models of Trichostrongylidae, etiology consistent with Molineus torulosus. This study describes the first cases of parasitism in Sapajus flavius, a species previously considered extinct, but recently rediscovered, and presents the occurrence of M. torulosus in two other species, Sapajus libidinosus and Sapajus apella.

A comparative study of plasma heating by ion acoustic and modified two-stream instabilities at subcritical quasi-perpendicular shocks

International Nuclear Information System (INIS)

Winske, D.; Giacalone, J.; Thomsen, M.F.; Mellott, M.M.

1987-01-01

Plasma heating due to the ion instability and the modified two-stream instability is examined for quasi-perpendicular subcritical shocks. Electron and ion heating is investigated as a function of upstream electron to ion temperature ratio and plasma beta using second-order heating rates. A simple shock model is employed in which the cross-field electron-ion drift speed is adjusted until the total (adiabatic plus anomalous) heating matches that required by the Rankine-Hugoniot relations. Quantities such as the width of the shock and the maximum electric field fluctuations are also calculated, and the results are compared with the ISEE data set of subcritical box shock crossings. The observed width of the shock, the amount of plasma heating, and the low-frequency electric field intensity are in reasonably good agreement with the calculations for the modified two-stream instability. On the other hand, the wave intensities at higher frequency are about 4 orders of magnitude smaller than those predicted for the ion acoustic instability at saturation, consistent with the fact that the measured shock widths imply cross-field drift speeds that are below threshold for this instability. It is therefore concluded that the dissipation at these shocks is most likely due to the lower frequency, modified two-stream instability

MEKANISME SEGMENTASI LAJU BIT PADA DYNAMIC ADAPTIVE STREAMING OVER HTTP (DASH UNTUK APLIKASI VIDEO STREAMING

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Muhammad Audy Bazly

2015-12-01

Full Text Available This paper aims to analyze Internet-based streaming video service in the communication media with variable bit rates. The proposed scheme on Dynamic Adaptive Streaming over HTTP (DASH using the internet network that adapts to the protocol Hyper Text Transfer Protocol (HTTP. DASH technology allows a video in the video segmentation into several packages that will distreamingkan. DASH initial stage is to compress the video source to lower the bit rate video codec uses H.26. Video compressed further in the segmentation using MP4Box generates streaming packets with the specified duration. These packages are assembled into packets in a streaming media format Presentation Description (MPD or known as MPEG-DASH. Streaming video format MPEG-DASH run on a platform with the player bitdash teritegrasi bitcoin. With this scheme, the video will have several variants of the bit rates that gave rise to the concept of scalability of streaming video services on the client side. The main target of the mechanism is smooth the MPEG-DASH streaming video display on the client. The simulation results show that the scheme based scalable video streaming MPEG- DASH able to improve the quality of image display on the client side, where the procedure bufering videos can be made constant and fine for the duration of video views

Exploring the diversity and distribution of neotropical avian malaria parasites--a molecular survey from Southeast Brazil.

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Gustavo A Lacorte

Full Text Available Southeast Brazil is a neotropical region composed of a mosaic of different tropical habitats and mountain chains, which allowed for the formation of bird-rich communities with distinct ecological niches. Although this region has the potential to harbor a remarkable variety of avian parasites, there is a lack of information about the diversity of malarial parasites. We used molecular approaches to characterize the lineage diversity of Plasmodium and Haemoproteus in bird communities from three different habitats in southeast Brazil based on the prevalence, richness and composition of lineages. We observed an overall prevalence of 35.3%, with a local prevalence ranging from 17.2% to 54.8%. Moreover, no significant association between prevalence and habitat type could be verified (p>0.05. We identified 89 Plasmodium and 22 Haemoproteus lineages, with 86% of them described for the first time here, including an unusual infection of a non-columbiform host by a Haemoproteus (Haemoproteus parasite. The composition analyses of the parasite communities showed that the lineage composition from Brazilian savannah and tropical dry forest was similar, but it was different from the lineage composition of Atlantic rainforest, reflecting the greater likeness of the former habitats with respect to seasonality and forest density. No significant effects of habitat type on lineage richness were observed based on GLM analyses. We also found that sites whose samples had a greater diversity of bird species showed a greater diversity of parasite lineages, providing evidence that areas with high bird richness also have high parasite richness. Our findings point to the importance of the neotropical region (southeast Brazil as a major reservoir of new haemosporidian lineages.

The effects of soils and soil stay on the egg morphology of Neotropical Eulimnadia (Branchiopoda: Limnadiidae

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Nicolas Rabet

2014-01-01

Full Text Available Studying the species distribution of Limnadiidae, a family of crustaceans, in environments favourable to their growth and reproduction is made difficult by their extremely short life cycle and the transient existence of adult forms. However, the eggs of these branchiopods are highly resistant to environmental extremes and persist in the soil of humidified and dried pools. We therefore studied the capacity to detect populations of Limnadiidae and identify them at the species level using egg morphology. We investigated influences of pool sediments on Eulimnadia (clam shrimp egg morphology and asked whether we could rely on this morphology after various lengths of time in the soil to recognise species. We studied sediment collected from temporary pools in four Neotropical areas: Minas Gerais and Bahia (Brazil, French Guiana, and Martinique. These samples represented diverse geographical regions and climates and allowed us to study the four most widely distributed Eulimnadia species in the Neotropics: E. colombiensis, E. cylindrova, E. geayi, and E. magdalensis. Our results indicated that soil abrasion is superficial and does not affect the general shape of the eggs (cylindrical or spherical. However, details of egg ornamentation can be severely affected by the combined effects of erosion and filling with sediments, which can lead to difficulties in species identification. In the particular case of the spherical eggs of E. magdalensis, this species cannot be unequivocally identified without clean eggs collected from adults after breeding or from eggs recently deposited in the field. This work and the investigative methods described herein should facilitate identification of Eulimnadia species and promote further study of Limnadiidae crustaceans in the field.

Relativistic nonlinear waves of cyclotron in electron and electron-ion plasmas

International Nuclear Information System (INIS)

Bruno, R.

1981-12-01

Dispersion relations for electron-cyclotron and ion-cyclotron waves are examined in two models of plasmas, the first propagating in fluent electronic plasmas (''streaming'') as well as in fluent electron-ionic plasmas, and the last in fluent electron-ionic plasmas. The identification of the propagation modes is realized with the aid of a special technique of polinomial expantion of the dispersion relation in the limit of large frequencies and short wavelenghts. The analisys so developed on these dispersion relations for fluent plasmas show that: (i) the wave amplitudes are frequency dependent; (ii) the ''resonances'' frequencies of the respective estationary plasmas must be re-examined with the relations between wave amplitudes and the propagation frequencies near these frequencies; (iii) the electric field amplitudes for the non-linear waves of electron-cyclotron and ion-cyclotron go to zero in the limits of the respective cyclotron frequencies in both fluent plasma models. (M.W.O.) [pt

The dynamics of electron and ion holes in a collisionless plasma

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B. Eliasson

2005-01-01

Full Text Available We present a review of recent analytical and numerical studies of the dynamics of electron and ion holes in a collisionless plasma. The new results are based on the class of analytic solutions which were found by Schamel more than three decades ago, and which here work as initial conditions to numerical simulations of the dynamics of ion and electron holes and their interaction with radiation and the background plasma. Our analytic and numerical studies reveal that ion holes in an electron-ion plasma can trap Langmuir waves, due the local electron density depletion associated with the negative ion hole potential. Since the scale-length of the ion holes are on a relatively small Debye scale, the trapped Langmuir waves are Landau damped. We also find that colliding ion holes accelerate electron streams by the negative ion hole potentials, and that these streams of electrons excite Langmuir waves due to a streaming instability. In our Vlasov simulation of two colliding ion holes, the holes survive the collision and after the collision, the electron distribution becomes flat-topped between the two ion holes due to the ion hole potentials which work as potential barriers for low-energy electrons. Our study of the dynamics between electron holes and the ion background reveals that standing electron holes can be accelerated by the self-created ion cavity owing to the positive electron hole potential. Vlasov simulations show that electron holes are repelled by ion density minima and attracted by ion density maxima. We also present an extension of Schamel's theory to relativistically hot plasmas, where the relativistic mass increase of the accelerated electrons have a dramatic effect on the electron hole, with an increase in the electron hole potential and in the width of the electron hole. A study of the interaction between electromagnetic waves with relativistic electron holes shows that electromagnetic waves can be both linearly and nonlinearly

POLA RASIO KEUANGAN PADA SAAT UP STREAM DAN DOWN STREAM DI INDUSTRI REALESTAT YANG GO PUBLIC

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David Sukardi Kodrat

2006-01-01

Full Text Available This research has purpose to explain differences on indicator financial ratio in up and down stream condition. This research uses real estate industries listed on Jakarta Stock Exchange as a sample. Sample selection is performed based on purposive sampling method with object to gain sample according to the research aim. Based on those criteria, there are 18 companies, which have fulfilling the conditions needed, starting from 1994 until 2002. The classification of business cycle on up and down stream conditions to used stock pricing indexes of property and real estate which calculated by arithmatic mean method. Based on those criteria, the classifications from 1994 until 1997 are represented by up stream condition and from 1998 until 2002 are represented by down stream condition. The result shows indicators: profitability ratios, gross margin ratios, capital turnover ratios, asset to equity ratios, growth ratios, liquidity ratios, leverage ratios, and cash flow ratios are different in up and down stream conditions, both simultaneously and partially. Simultaneously, there is a significant difference between up and down stream condition with wilks lambda of 0,346 and p value of 0,000. This research shows financial ratio indicator has differences on business cycle. Abstract in Bahasa Indonesia : Penelitan ini mempunyai tujuan untuk mengetahui perbedaan indikator rasio keuangan pada kondisi up stream dan down stream. Penelitian ini menggunakan sampel pada industri di sektor properti yang terdaftar di Bursa Efek Jakarta. Pemilihan sampel dalam penelitian ini menggunakan Purposive Sampling yaitu sampel diambil berdasarkan kriteria-kriteria tertentu yang sesuai dengan tujuan penelitian ini. Berdasarkan kriteria tersebut, terdapat 18 perusahaan yang dapat dijadikan sampel mulai tahun 1994 sampai dengan 2002. Untuk menentukan perubahan business cycle pada kondisi up stream dan down stream dilakukan dengan menggunakan indeks harga saham di sektor properti

Developing user-friendly habitat suitability tools from regional stream fish survey data

Science.gov (United States)

Zorn, T.G.; Seelbach, P.; Wiley, M.J.

2011-01-01

We developed user-friendly fish habitat suitability tools (plots) for fishery managers in Michigan; these tools are based on driving habitat variables and fish population estimates for several hundred stream sites throughout the state. We generated contour plots to show patterns in fish biomass for over 60 common species (and for 120 species grouped at the family level) in relation to axes of catchment area and low-flow yield (90% exceedance flow divided by catchment area) and also in relation to axes of mean and weekly range of July temperatures. The plots showed distinct patterns in fish habitat suitability at each level of biological organization studied and were useful for quantitatively comparing river sites. We demonstrate how these plots can be used to support stream management, and we provide examples pertaining to resource assessment, trout stocking, angling regulations, chemical reclamation of marginal trout streams, indicator species, instream flow protection, and habitat restoration. These straightforward and effective tools are electronically available so that managers can easily access and incorporate them into decision protocols and presentations.

Neotropical genera of Naucoridae (Hemiptera: Heteroptera: Nepomorpha): new species of Placomerus and Procryphocricos from Guyana and Venezuela.

Science.gov (United States)

Sites, Robert W; Camacho, Jesús

2014-01-09

The Neotropical fauna of saucer bugs (Naucoridae) currently includes four monotypic genera. Recent extensive collecting in Venezuela has produced three new species in two of these genera. In addition, undetermined Guyanan specimens of one of the new species were found in the United States National Museum of Natural History. Thus, described here are Placomerus obscuratus n. sp. from Guyana and Venezuela with brachypterous and macropterous hindwing forms, and two species of Procryphocricos from Venezuela. Procryphocricos quiu n. sp. is described from the brachypterous forewing form and Procryphocricos macoita n. sp. from both brachypterous and macropterous forms. Previously described species also are discussed.

HUNTING THE PARENT OF THE ORPHAN STREAM: IDENTIFYING STREAM MEMBERS FROM LOW-RESOLUTION SPECTROSCOPY

International Nuclear Information System (INIS)

Casey, Andrew R.; Da Costa, Gary; Keller, Stefan C.; Maunder, Elizabeth

2013-01-01

We present candidate K-giant members in the Orphan Stream that have been identified from low-resolution data taken with the AAOmega spectrograph on the Anglo-Australian Telescope. From modest signal-to-noise spectra and independent cuts in photometry, kinematics, gravity, and metallicity we yield self-consistent, highly probable stream members. We find a revised stream distance of 22.5 ± 2.0 kpc near the celestial equator and our kinematic signature peaks at V GSR = 82.1 ± 1.4 km s –1 . The observed velocity dispersion of our most probable members is consistent with arising from the velocity uncertainties alone. This indicates that at least along this line of sight, the Orphan Stream is kinematically cold. Our data indicate an overall stream metallicity of [Fe/H] = –1.63 ± 0.19 dex which is more metal-rich than previously found and unbiased by spectral type. Furthermore, the significant metallicity dispersion displayed by our most probable members, σ([Fe/H]) = 0.56 dex, suggests that the unidentified Orphan Stream parent is a dSph satellite. We highlight likely members for high-resolution spectroscopic follow-up.

In-stream nutrient uptake kinetics along stream size and development gradients in a rapidly developing mountain resort watershed

Science.gov (United States)

Covino, T.; McGlynn, B.; McNamarra, R.; Gardner, K.

2012-04-01

Land use / land cover (LULC) change including mountain resort development often lead to increased nutrient loading to streams, however the potential influence on stream ecosystem nutrient uptake kinetics and transport remain poorly understood. Given the deleterious impacts elevated nutrient loading can have on aquatic ecosystems, it is imperative to improve understanding of nutrient retention capacities across stream scales and watershed development intensities. We performed seventeen nutrient addition experiments on six streams across the West Fork Gallatin Watershed, Montana, USA, to quantify nitrogen (N) uptake kinetics and retention dynamics across stream sizes (1st to 4th order) and along a mountain resort development gradient. We observed that stream N uptake kinetics and spiraling parameters varied across streams of different development intensity and scale. In more developed watersheds we observed a fertilization affect, however, none of the streams exhibited saturation with respect to N. Additionally, we observed that elevated loading led to increased biomass and retentive capacities in developed streams that helped maintain export at low levels during baseflow. Our results indicate that LULC can enhance in-stream uptake of limiting nutrients and highlight the value of characterizing uptake kinetic curves from ambient to saturation.

Stream invertebrate productivity linked to forest subsidies: 37 stream-years of reference and experimental data

Science.gov (United States)

J. Bruce Wallace; Susan L Eggert; Judy L. Meyer; Jackson R. Webster

2015-01-01

Riparian habitats provide detrital subsidies of varying quantities and qualities to recipient ecosystems. We used long-term data from three reference streams (covering 24 stream-years) and 13-year whole-stream organic matter manipulations to investigate the influence of terrestrial detrital quantity and quality on benthic invertebrate community structure, abundance,...

Biometry of neotropical invertebrates inhabiting floodplain rivers: unraveling bionomy

Directory of Open Access Journals (Sweden)

Florencia Zilli

Full Text Available ABSTRACT Currently, it is widely recognized that invertebrates play key roles in neotropical floodplains and in many other environments worldwide. However, little information has been published concerning their biometry, in spite that it represents an essential tool for many different studies. Here, we provided length-mass and length-length relationships by fitting the linearized model (log10 Y = log10a + b log10 X and several mean biomass ratios ± SE for bivalves, gastropods, quironomids, ephemeropterans, oligochaetes and hirudineans. We measured, weighed, oven dried and incinerated to ashes specimens collected from 2005 to 2014 in the Paraná River, Argentina. The lineal equations had fit levels higher than 75% in most of the significant regressions. Hence, when slopes were compared, differences raised from ontogeny and phylogeny of taxa. Additionally, slopes resulted different from constants of other regions, types of environments and climates. In addition, organic matter ratios resulted significantly different among invertebrates according to their feeding types. The equations and ratios that we provided will facilitate future research on life history, productivity and energy transference in the food webs of invertebrates inhabiting floodplain wetlands and can be used as tools for planning management strategies and in restoration projects of aquatic environments.

Complementary roles of two resilient neotropical mammalian seed dispersers

Science.gov (United States)

de Almeida, Adriana; Morris, Rebecca J.; Lewis, Owen T.; Mikich, Sandra B.

2018-04-01

Capuchin monkeys (Cebus spp. and Sapajus spp.) and coatis (Nasua spp.) coexist in most neotropical forests, including small forest remnants. Both capuchins and coatis eat fruit and disperse seeds, but little is known about whether their roles in seed dispersal are redundant or complementary. We compiled 49 studies from the literature on feeding by capuchins and/or coatis, of which 19 were comprehensive enough for our analyses. We determined the relative importance of fruit eating to each species and compared their diets. Additionally, we analysed the structure of three fruit-frugivore networks built with both animal groups and the fruits they eat and evaluated whether fruit traits influenced the network topology. Fruits represented the largest part of capuchin and coati diets, even though coatis have been known for their opportunistic and generalist diets. Capuchins and coatis also exhibited similar general diet parameters (niche breadth and trophic diversity). The three networks exhibited high connectance values and variable niche overlap. A Multiple Correspondence Analysis, failed to detect any trait or trait combination related to food use. In conclusion, capuchins and coatis both have generalist diets; they feed on many different species of fruits and exhibit important complementarity as seed dispersers. Both are likely to be particularly important seed dispersers in disturbed and fragmented forests.

Landscape matrix mediates occupancy dynamics of Neotropical avian insectivores

Science.gov (United States)

Kennedy, Christina M.; Campbell Grant, Evan H.; Neel, Maile C.; Fagan, William F.; Marpa, Peter P.

2011-01-01

In addition to patch-level attributes (i.e., area and isolation), the nature of land cover between habitat patches (the matrix) may drive colonization and extinction dynamics in fragmented landscapes. Despite a long-standing recognition of matrix effects in fragmented systems, an understanding of the relative impacts of different types of land cover on patterns and dynamics of species occurrence remains limited. We employed multi-season occupancy models to determine the relative influence of patch area, patch isolation, within-patch vegetation structure, and landscape matrix on occupancy dynamics of nine Neotropical nsectivorous birds in 99 forest patches embedded in four matrix types (agriculture, suburban evelopment, bauxite mining, and forest) in central Jamaica. We found that within-patch vegetation structure and the matrix type between patches were more important than patch area and patch isolation in determining local colonization and local extinction probabilities, and that the effects of patch area, isolation, and vegetation structure on occupancy dynamics tended to be matrix and species dependent. Across the avian community, the landscape matrix influenced local extinction more than local colonization, indicating that extinction processes, rather than movement, likely drive interspecific differences in occupancy dynamics. These findings lend crucial empirical support to the hypothesis that species occupancy dynamics in fragmented systems may depend greatly upon the landscape context.

Electron cyclotron harmonic wave acceleration

Science.gov (United States)

Karimabadi, H.; Menyuk, C. R.; Sprangle, P.; Vlahos, L.

1987-01-01

A nonlinear analysis of particle acceleration in a finite bandwidth, obliquely propagating electromagnetic cyclotron wave is presented. It has been suggested by Sprangle and Vlahos in 1983 that the narrow bandwidth cyclotron radiation emitted by the unstable electron distribution inside a flaring solar loop can accelerate electrons outside the loop by the interaction of a monochromatic wave propagating along the ambient magnetic field with the ambient electrons. It is shown here that electrons gyrating and streaming along a uniform, static magnetic field can be accelerated by interacting with the fundamental or second harmonic of a monochromatic, obliquely propagating cyclotron wave. It is also shown that the acceleration is virtually unchanged when a wave with finite bandwidth is considered. This acceleration mechanism can explain the observed high-energy electrons in type III bursts.

Electron cyclotron harmonic wave acceleration

International Nuclear Information System (INIS)

Karimabadi, H.; Menyuk, C.R.; Sprangle, P.; Vlahos, L.; Salonika Univ., Greece)

1987-01-01

A nonlinear analysis of particle acceleration in a finite bandwidth, obliquely propagating electromagnetic cyclotron wave is presented. It has been suggested by Sprangle and Vlahos in 1983 that the narrow bandwidth cyclotron radiation emitted by the unstable electron distribution inside a flaring solar loop can accelerate electrons outside the loop by the interaction of a monochromatic wave propagating along the ambient magnetic field with the ambient electrons. It is shown here that electrons gyrating and streaming along a uniform, static magnetic field can be accelerated by interacting with the fundamental or second harmonic of a monochromatic, obliquely propagating cyclotron wave. It is also shown that the acceleration is virtually unchanged when a wave with finite bandwidth is considered. This acceleration mechanism can explain the observed high-energy electrons in type III bursts. 31 references

How wide is a stream? Spatial extent of the potential "stream signature" in terrestrial food webs using meta-analysis.

Science.gov (United States)

Muehlbauer, Jeffrey D; Collins, Scott F; Doyle, Martin W; Tockner, Klement

2014-01-01

The magnitude of cross-ecosystem resource subsidies is increasingly well recognized; however, less is known about the distance these subsidies travel into the recipient landscape. In streams and rivers, this distance can delimit the "biological stream width," complementary to hydro-geomorphic measures (e.g., channel banks) that have typically defined stream ecosystem boundaries. In this study we used meta-analysis to define a "stream signature" on land that relates the stream-to-land subsidy to distance. The 50% stream signature, for example, identifies the point on the landscape where subsidy resources are still at half of their maximum (in- or near-stream) level. The decay curve for these data was best fit by a negative power function in which the 50% stream signature was concentrated near stream banks (1.5 m), but a non-trivial (10%) portion of the maximum subsidy level was still found > 0.5 km from the water's edge. The meta-analysis also identified explanatory variables that affect the stream signature. This improves our understanding of ecosystem conditions that permit spatially extensive subsidy transmission, such as in highly productive, middle-order streams and rivers. Resultant multivariate models from this analysis may be useful to managers implementing buffer rules and conservation strategies for stream and riparian function, as they facilitate prediction of the extent of subsidies. Our results stress that much of the subsidy remains near the stream, but also that subsidies (and aquatic organisms) are capable of long-distance dispersal into adjacent environments, and that the effective "biological stream width" of stream and river ecosystems is often much larger than has been defined by hydro-geomorphic metrics alone. Limited data available from marine and lake sources overlap well with the stream signature data, indicating that the "signature" approach may also be applicable to subsidy spatial dynamics across other ecosystems.

The Northeast Stream Quality Assessment

Science.gov (United States)

Van Metre, Peter C.; Riva-Murray, Karen; Coles, James F.

2016-04-22

In 2016, the U.S. Geological Survey (USGS) National Water-Quality Assessment (NAWQA) is assessing stream quality in the northeastern United States. The goal of the Northeast Stream Quality Assessment (NESQA) is to assess the quality of streams in the region by characterizing multiple water-quality factors that are stressors to aquatic life and evaluating the relation between these stressors and biological communities. The focus of NESQA in 2016 will be on the effects of urbanization and agriculture on stream quality in all or parts of eight states: Connecticut, Massachusetts, New Hampshire, New Jersey, New York, Pennsylvania, Rhode Island, and Vermont.Findings will provide the public and policymakers with information about the most critical factors affecting stream quality, thus providing insights about possible approaches to protect the health of streams in the region. The NESQA study will be the fourth regional study conducted as part of NAWQA and will be of similar design and scope to the first three, in the Midwest in 2013, the Southeast in 2014, and the Pacific Northwest in 2015 (http://txpub.usgs.gov/RSQA/).

What Can Hierarchies Do for Data Streams?

DEFF Research Database (Denmark)

Yin, Xuepeng; Pedersen, Torben Bach

Much effort has been put into building data streams management systems for querying data streams. Here, data streams have been viewed as a flow of low-level data items, e.g., sensor readings or IP packet data. Stream query languages have mostly been SQL-based, with the STREAM and TelegraphCQ lang...

StreamSqueeze: a dynamic stream visualization for monitoring of event data

Science.gov (United States)

Mansmann, Florian; Krstajic, Milos; Fischer, Fabian; Bertini, Enrico

2012-01-01

While in clear-cut situations automated analytical solution for data streams are already in place, only few visual approaches have been proposed in the literature for exploratory analysis tasks on dynamic information. However, due to the competitive or security-related advantages that real-time information gives in domains such as finance, business or networking, we are convinced that there is a need for exploratory visualization tools for data streams. Under the conditions that new events have higher relevance and that smooth transitions enable traceability of items, we propose a novel dynamic stream visualization called StreamSqueeze. In this technique the degree of interest of recent items is expressed through an increase in size and thus recent events can be shown with more details. The technique has two main benefits: First, the layout algorithm arranges items in several lists of various sizes and optimizes the positions within each list so that the transition of an item from one list to the other triggers least visual changes. Second, the animation scheme ensures that for 50 percent of the time an item has a static screen position where reading is most effective and then continuously shrinks and moves to the its next static position in the subsequent list. To demonstrate the capability of our technique, we apply it to large and high-frequency news and syslog streams and show how it maintains optimal stability of the layout under the conditions given above.

Stream temperature responses to timber harvest and best management practices—findings from the ODF RipStream project

Science.gov (United States)

Jeremy D. Groom

2013-01-01

Studies over the past 40 years have established that riparian buff er retention along streams protects against stream temperature increase. Th is protection is neither universal nor complete; some buff ered streams still warm, while other streams’ temperatures remain stable. Oregon Department of Forestry developed riparian rules in the Forest Practices Act (FPA) to...

Percent Forest Adjacent to Streams (Future)

Data.gov (United States)

U.S. Environmental Protection Agency — The type of vegetation along a stream influences the water quality in the stream. Intact buffer strips of natural vegetation along streams tend to intercept...

Percent Agriculture Adjacent to Streams (Future)

Data.gov (United States)

U.S. Environmental Protection Agency — The type of vegetation along a stream influences the water quality in the stream. Intact buffer strips of natural vegetation along streams tend to intercept...

Ecological health in the Nation's streams

Science.gov (United States)

Carlisle, Daren M.; Woodside, Michael D.

2013-01-01

Aquatic biological communities, which are collections of organisms, are a direct measure of stream health because they indicate the ability of a stream to support life. This fact sheet highlights selected findings of a national assessment of stream health by the National Water-Quality Assessment (NAWQA) Program of the U.S. Geological Survey (USGS). The assessment was unique in that it integrated the condition of three biological communities—algae, macroinvertebrates, and fish—as well as measures of streamflow modification, pesticides, nutrients, and other factors. At least one biological community was altered at 83 percent of assessed streams, and the occurrence of altered communities was highest in urban streams. Streamflows were modified at 86 percent of assessed streams, and increasing severity of streamflow modification was associated with increased occurrence of altered biological communities. Agricultural and urban land use in watersheds may contribute pesticides and nutrients to stream waters, and increasing concentrations of these chemicals were associated with increased occurrence of altered biological communities.

Environmental enrichment for neotropical primates in captivity Enriquecimento ambiental para primatas neotropicais em cativeiro

Directory of Open Access Journals (Sweden)

Vanner Boere

2001-06-01

Full Text Available Captivity is an extreme non-natural environment for primates. The success of a breeding colony depends of management and veterinarian procedures which must rely on the knowledge of primates' behavioral needs. Environmental enrichment consists of a series of procedures that improve the quality of life of captive animals by meeting their ethological needs. Enrichment can reduce stress, while increasing animal well being in captivity. Suitable ethical conditions, incidences of behavioral disorders, minimal clinical interventions, low mortality, higher reproduction rates and cost/benefit relationship, reflect directly on the quality of captive breeding colonies. Anthropoids like Neotropical primates possess complex neural structures and relate, in a sophisticated manner, to the environment. This review reports important experiences on enrichment procedures for Neotropical primates and the physiological events which could explain improvement of animal well-being.Cativeiro é um ambiente de extremos não naturais para primatas. O sucesso de uma criação de primatas depende do manejo e de procedimentos veterinários que devem considerar as necessidades etológicas dos animais cativos. Enriquecimento ambiental é um conjunto de técnicas que modificam o ambiente, resultando em uma melhora na qualidade de vida dos animais, ao satisfazer as suas necessidades comportamentais. O enriquecimento pode diminuir o estresse e melhorar o bem-estar. Primatas neotropicais se caracterizam por complexas estruturas neurais e se relacionam de maneira sofisticada com o ambiente. O enriquecimento ambiental pode aumentar a qualidade de uma criação ao adequar o manejo a padrões éticos aceitáveis, estimular o repertório normal do comportamento, diminuir a casuística clínica, diminuir a mortalidade, incrementar a taxa reprodutiva e maximizar a relação custo/benefício em uma criação. Esta revisão relata experiências relevantes nos procedimentos de

Linear Gain and Gain Saturation in a Photonic Free-Electron Laser

NARCIS (Netherlands)

Denis, T.; Boller, Klaus J.; Lee, J.H.H.; van der Slot, P.J.M.; van Dijk, Marc

2012-01-01

Photonic crystals are used to manipulate the generation of light, for example, stimulated emission can be enhanced. A photonic free-electron laser (pFEL) applies this enhancement to generate widely tunable coherent Cerenkov radiation from low energy electrons (keV) streaming through the photonic

Comparison of active and passive stream restoration

DEFF Research Database (Denmark)

Kristensen, Esben Astrup; Thodsen, Hans; Dehli, Bjarke

2013-01-01

Modification and channelization of streams and rivers have been conducted extensively throughout the world during the past century. Subsequently, much effort has been directed at re-creating the lost habitats and thereby improving living conditions for aquatic organisms. However, as restoration...... methods are plentiful, it is difficult to determine which one to use to get the anticipated result. The aim of this study was to compare two commonly used methods in small Danish streams to improve the physical condition: re-meandering and passive restoration through cease of maintenance. Our...... investigation included measurement of the physical conditions in 29 stream reaches covering four different groups: (1) re-meandered streams, (2) LDC streams (the least disturbed streams available), (3) passively restored streams (>10 years stop of aintenance) and (4) channelized and non-restored streams. The in...

On Neotropical Merophysiinae with descriptions of a new genus and new species (Coleoptera, Endomychidae)

Science.gov (United States)

Arriaga-Varela, Emmanuel; Tomaszewska, Wioletta; Huo, Lizhi; Seidel, Matthias

2018-01-01

Abstract Intensive survey of museum collections and new field collecting resulted in discovery of six new, closely related species of the Neotropical Merophysiinae. A new species of the genus Lycoperdinella Champion, L. boliviensis sp. n., from Bolivia and Brazil, and five new species from Mexico for which a new genus is proposed here as Rueckeria gen. n.: R. inecol (type species), R. nigrileonis, R. ocelotl, R. puma, R. skelleyi spp. n., have been discovered. Lycoperdinella, Rueckeria gen. n., L. subcaeca Champion and all new species are diagnosed, described, and illustrated. Keys to the species of Lycoperdinella and Rueckeria and a distribution map are provided. A lectotype of Lycoperdinella subcaeca Champion, 1913 is designated. Molecular barcodes of three new species of Rueckeria are provided in order to help with the identification of these taxa. PMID:29674866

The Pacific northwest stream quality assessment

Science.gov (United States)

Van Metre, Peter C.; Morace, Jennifer L.; Sheibley, Rich W.

2015-01-01

In 2015, the U.S. Geological Survey (USGS) National Water-Quality Assessment (NAWQA) program is assessing stream quality in the Pacific Northwest. The goals of the Pacific Northwest Stream Quality Assessment (Pacific Northwest study) are to assess the quality of streams in the region by characterizing multiple water-quality factors that are stressors to aquatic life and to evaluate the relation between these stressors and biological communities. The effects of urbanization and agriculture on stream quality for the Puget Lowlands and Willamette Valley are the focus of this regional study. Findings will provide the public and policymakers with information regarding which human and environmental factors are the most critical in affecting stream quality and, thus, provide insights about possible approaches to protect or improve the health of streams in the region.

Chironomidae larvae (Diptera) of Neotropical floodplain: overlap niche in different habitats.

Science.gov (United States)

Butakka, C M M; Ragonha, F H; Takeda, A M

2014-05-01

The niche overlap between trophic groups of Chironomidae larvae in different habitats was observed between trophic groups and between different environments in Neotropical floodplain. For the evaluation we used the index of niche overlap (CXY) and analysis of trophic networks, both from the types and amount of food items identified in the larval alimentary canal. In all environments, the larvae fed on mainly organic matter such as plants fragments and algae, but there were many omnivore larvae. Species that have high values of food items occurred in diverse environments as generalists with great overlap niche and those with a low amount of food items with less overlap niche were classified as specialists. The largest number of trophic niche overlap was observed among collector-gatherers in connected floodplain lakes. The lower values of index niche overlap were predators. The similarity in the diet of different taxa in the same niche does not necessarily imply competition between them, but coexistence when the food resource is not scarce in the environment even in partially overlapping niches.

An ecohydrological stream type cassification of intermittent and ephemeral streams in the Southwestern United States 2397

Science.gov (United States)

Ephemeral and intermittent streams are the predominant fluvial forms in arid and semi-arid environments. Various studies have shown biological and habitat diversity in these lands to be considerably higher along stream corridors in comparison to adjacent uplands, yet knowledge of how these streams f...

Coherent counter-steaming electrostatic wave Raman interaction system utilizing opposing electron beams for the production of coherent microwaves in plasmas

International Nuclear Information System (INIS)

Leiby, C.C. Jr.; Prasad, B.

1977-01-01

The generation of controlled, electromagnetic, coherent, microwave radiation from a warm, uniform plasma at approximately twice the electron plasma frequency by means of two oppositely directed streams of high energy electrons and the coupling of the resulting coherent, electromagnetic radiation from a cavity resonator into external circuitry, wherein the two opposing streams of high energy electrons directed into the warm, uniform plasma result in a conversion of electron beam and plasma energies into transverse electromagnetic radiation from 10 to 100 times that which is possible with a single electron beam-plasma system. 7 claims, 4 figures

Streaming Media Seminar--Effective Development and Distribution of Streaming Multimedia in Education

Science.gov (United States)

Mainhart, Robert; Gerraughty, James; Anderson, Kristine M.

2004-01-01

Concisely defined, "streaming media" is moving video and/or audio transmitted over the Internet for immediate viewing/listening by an end user. However, at Saint Francis University's Center of Excellence for Remote and Medically Under-Served Areas (CERMUSA), streaming media is approached from a broader perspective. The working definition includes…

Transport of runaway and thermal electrons due to magnetic microturbulence

International Nuclear Information System (INIS)

Mynick, H.E.; Strachan, J.D.

1981-01-01

The ratio of the runaway electron confinement to thermal electron energy confinement is derived for tokamaks where both processes are determined by free streaming along stochastic magnetic field lines. The runaway electron confinement is enhanced at high runaway electron energies due to phase averaging over the magnetic perturbations when the runaway electron drift surfaces are displaced from the magnetic surfaces. Comparison with experimental data from LT-3, Ormak, PLT, ST, and TM-3 indicates that magnetic stochasticity may explain the relative transport rates of runaways and thermal electron energy

Process for humidifying a gaseous fuel stream

International Nuclear Information System (INIS)

Sederquist, R. A.

1985-01-01

A fuel gas stream for a fuel cell is humidified by a recirculating hot liquid water stream using the heat of condensation from the humidified stream as the heat to vaporize the liquid water. Humidification is accomplished by directly contacting the liquid water with the dry gas stream in a saturator to evaporate a small portion of water. The recirculating liquid water is reheated by direct contact with the humidified gas stream in a condenser, wherein water is condensed into the liquid stream. Between the steps of humidifying and condensing water from the gas stream it passes through the fuel cell and additional water, in the form of steam, is added thereto

Stochastic ice stream dynamics.

Science.gov (United States)

Mantelli, Elisa; Bertagni, Matteo Bernard; Ridolfi, Luca

2016-08-09

Ice streams are narrow corridors of fast-flowing ice that constitute the arterial drainage network of ice sheets. Therefore, changes in ice stream flow are key to understanding paleoclimate, sea level changes, and rapid disintegration of ice sheets during deglaciation. The dynamics of ice flow are tightly coupled to the climate system through atmospheric temperature and snow recharge, which are known exhibit stochastic variability. Here we focus on the interplay between stochastic climate forcing and ice stream temporal dynamics. Our work demonstrates that realistic climate fluctuations are able to (i) induce the coexistence of dynamic behaviors that would be incompatible in a purely deterministic system and (ii) drive ice stream flow away from the regime expected in a steady climate. We conclude that environmental noise appears to be crucial to interpreting the past behavior of ice sheets, as well as to predicting their future evolution.

Stream Tracker: Crowd sourcing and remote sensing to monitor stream flow intermittence

Science.gov (United States)

Puntenney, K.; Kampf, S. K.; Newman, G.; Lefsky, M. A.; Weber, R.; Gerlich, J.

2017-12-01

Streams that do not flow continuously in time and space support diverse aquatic life and can be critical contributors to downstream water supply. However, these intermittent streams are rarely monitored and poorly mapped. Stream Tracker is a community powered stream monitoring project that pairs citizen contributed observations of streamflow presence or absence with a network of streamflow sensors and remotely sensed data from satellites to track when and where water is flowing in intermittent stream channels. Citizens can visit sites on roads and trails to track flow and contribute their observations to the project site hosted by CitSci.org. Data can be entered using either a mobile application with offline capabilities or an online data entry portal. The sensor network provides a consistent record of streamflow and flow presence/absence across a range of elevations and drainage areas. Capacitance, resistance, and laser sensors have been deployed to determine the most reliable, low cost sensor that could be mass distributed to track streamflow intermittence over a larger number of sites. Streamflow presence or absence observations from the citizen and sensor networks are then compared to satellite imagery to improve flow detection algorithms using remotely sensed data from Landsat. In the first two months of this project, 1,287 observations have been made at 241 sites by 24 project members across northern and western Colorado.

Transverse two-stream instability in a matched plasma channel

International Nuclear Information System (INIS)

Whlttum, D.H.

1994-01-01

A relativistic electron beam magnetically self-focused in a plasma is subject to a transverse two stream or 'hose' instability. Linear evolution is described in terms of a tune distribution characterizing the beam, and an effective transverse impedance determined by the beam and the plasma profiles. This model is compared to cloud-in-cell simulations of three-dimensional transport of a beam with a Bennett profile, through a matched plasma channel. In the limit of large skin-depth this instability appears to be the primary limitation on stable beam transport. (author)

Structured multi-stream command language

International Nuclear Information System (INIS)

Glad, A.S.

1982-12-01

A multi-stream command language was implemented to provide the sequential and decision-making operations necessary to run the neutral-beam ion sources connected to the Doublet III tokamak fusion device. A multi-stream command language was implemented in Pascal on a Classic 7870 running under MAX IV. The purpose of this paper is threefold. First, to provide a brief description of the programs comprising the command language including the operating system interaction. Second, to give a description of the language syntax and commands necessary to develop a procedure stream. Third, to provide a description of the normal operating procedures for executing either the sequential or interactive streams

Acoustic streaming of a sharp edge.

Science.gov (United States)

Ovchinnikov, Mikhail; Zhou, Jianbo; Yalamanchili, Satish

2014-07-01

Anomalous acoustic streaming is observed emanating from sharp edges of solid bodies that are vibrating in fluids. The streaming velocities can be orders of magnitude higher than expected from the Rayleigh streaming at similar amplitudes of vibration. Acoustic velocity of fluid relative to a solid body diverges at a sharp edge, giving rise to a localized time-independent body force acting on the fluid. This force results in a formation of a localized jet. Two-dimensional numerical simulations are performed to predict acoustic streaming for low amplitude vibration using two methods: (1) Steady-state solution utilizing perturbation theory and (2) direct transient solution of the Navier-Stokes equations. Both analyses agree with each other and correctly predict the streaming of a sharp-edged vibrating blade measured experimentally. The origin of the streaming can be attributed to the centrifugal force of the acoustic fluid flow around a sharp edge. The dependence of this acoustic streaming on frequency and velocity is examined using dimensional analysis. The dependence law is devised and confirmed by numerical simulations.

Body Size Adaptations to Altitudinal Climatic Variation in Neotropical Grasshoppers of the Genus Sphenarium (Orthoptera: Pyrgomorphidae)

Science.gov (United States)

2015-01-01

Altitudinal clines in body size can result from the effects of natural and sexual selection on growth rates and developing times in seasonal environments. Short growing and reproductive seasons constrain the body size that adults can attain and their reproductive success. Little is known about the effects of altitudinal climatic variation on the diversification of Neotropical insects. In central Mexico, in addition to altitude, highly heterogeneous topography generates diverse climates that can occur even at the same latitude. Altitudinal variation and heterogeneous topography open an opportunity to test the relative impact of climatic variation on body size adaptations. In this study, we investigated the relationship between altitudinal climatic variation and body size, and the divergence rates of sexual size dimorphism (SSD) in Neotropical grasshoppers of the genus Sphenarium using a phylogenetic comparative approach. In order to distinguish the relative impact of natural and sexual selection on the diversification of the group, we also tracked the altitudinal distribution of the species and trends of both body size and SSD on the phylogeny of Sphenarium. The correlative evidence suggests no relationship between altitude and body size. However, larger species were associated with places having a warmer winter season in which the temporal window for development and reproduction can be longer. Nonetheless, the largest species were also associated with highly seasonal environments. Moreover, large body size and high levels of SSD have evolved independently several times throughout the history of the group and male body size has experienced a greater evolutionary divergence than females. These lines of evidence suggest that natural selection, associated with seasonality and sexual selection, on maturation time and body size could have enhanced the diversification of this insect group. PMID:26684616

Spatial Scales of Genetic Structure in Free-Standing and Strangler Figs (Ficus, Moraceae Inhabiting Neotropical Forests.

Directory of Open Access Journals (Sweden)

Katrin Heer

Full Text Available Wind-borne pollinating wasps (Agaonidae can transport fig (Ficus sp., Moraceae pollen over enormous distances (> 100 km. Because of their extensive breeding areas, Neotropical figs are expected to exhibit weak patterns of genetic structure at local and regional scales. We evaluated genetic structure at the regional to continental scale (Panama, Costa Rica, and Peru for the free-standing fig species Ficus insipida. Genetic differentiation was detected only at distances > 300 km (Jost´s Dest = 0.68 ± 0.07 & FST = 0.30 ± 0.03 between Mesoamerican and Amazonian sites and evidence for phylogeographic structure (RST>>permuted RST was only significant in comparisons between Central and South America. Further, we assessed local scale spatial genetic structure (SGS, d ≤ 8 km in Panama and developed an agent-based model parameterized with data from F. insipida to estimate minimum pollination distances, which determine the contribution of pollen dispersal on SGS. The local scale data for F. insipida was compared to SGS data collected for an additional free-standing fig, F. yoponensis (subgenus Pharmacosycea, and two species of strangler figs, F. citrifolia and F. obtusifolia (subgenus Urostigma sampled in Panama. All four species displayed significant SGS (mean Sp = 0.014 ± 0.012. Model simulations indicated that most pollination events likely occur at distances > > 1 km, largely ruling out spatially limited pollen dispersal as the determinant of SGS in F. insipida and, by extension, the other fig species. Our results are consistent with the view that Ficus develops fine-scale SGS primarily as a result of localized seed dispersal and/or clumped seedling establishment despite extensive long-distance pollen dispersal. We discuss several ecological and life history factors that could have species- or subgenus-specific impacts on the genetic structure of Neotropical figs.

Global perspectives on the urban stream syndrome

Science.gov (United States)

Roy, Allison; Booth, Derek B.; Capps, Krista A.; Smith, Benjamin

2016-01-01

Urban streams commonly express degraded physical, chemical, and biological conditions that have been collectively termed the “urban stream syndrome”. The description of the syndrome highlights the broad similarities among these streams relative to their less-impaired counterparts. Awareness of these commonalities has fostered rapid improvements in the management of urban stormwater for the protection of downstream watercourses, but the focus on the similarities among urban streams has obscured meaningful differences among them. Key drivers of stream responses to urbanization can vary greatly among climatological and physiographic regions of the globe, and the differences can be manifested in individual stream channels even through the homogenizing veneer of urban development. We provide examples of differences in natural hydrologic and geologic settings (within similar regions) that can result in different mechanisms of stream ecosystem response to urbanization and, as such, should lead to different management approaches. The idea that all urban streams can be cured using the same treatment is simplistic, but overemphasizing the tremendous differences among natural (or human-altered) systems also can paralyze management. Thoughtful integration of work that recognizes the commonalities of the urban stream syndrome across the globe has benefitted urban stream management. Now we call for a more nuanced understanding of the regional, subregional, and local attributes of any given urban stream and its watershed to advance the physical, chemical, and ecological recovery of these systems.

Organic carbon spiralling in stream ecosystems

Energy Technology Data Exchange (ETDEWEB)

Newbold, J D; Mulholland, P J; Elwood, J W; O' Neill, R V

1982-01-01

The term spiralling has been used to describe the combined processes of cycling and longitudinal transport in streams. As a measure or organic carbon spiralling, we introduced organic carbon turnover length, S, defined as the average or expected downstream distance travelled by a carbon atom between its entry or fixation in the stream and its oxidation. Using a simple model for organic carbon dynamics in a stream, we show that S is closely related to fisher and Likens' ecosystem efficiency. Unlike efficiency, however, S is independent of the length of the study reach, and values of S determined in streams of differing lengths can be compared. Using data from three different streams, we found the relationship between S and efficiency to agree closely with the model prediction. Hypotheses of stream functioning are discussed in the context of organic carbeon spiralling theory.

Probing of flowing electron plasmas

International Nuclear Information System (INIS)

Himura, H.; Nakashima, C.; Saito, H.; Yoshida, Z.

2001-01-01

Probing of streaming electron plasmas with finite temperature is studied. For the first time, a current-voltage characteristic of an electric probe is measured in electron plasmas. Due to the fast flow of the electron plasmas, the characteristic curve spreads out significantly and exhibits a long tail. This feature can be explained calculating the currents collected to the probe. In flowing electron plasmas, the distribution function observed in the laboratory frame is non-Maxwellian even if the plasmas come to a state of thermal equilibrium. Another significant feature of the characteristic is that it determines a floating potential where the current equals zero, despite there being very few ions in the electron plasma. A high impedance probe, which is popularly used to determine the space potential of electron plasmas, outputs the potential. The method is available only for plasmas with density much smaller than the Brillouin limit

Three new species and reassessment of the rare Neotropical ant genus Leptanilloides (Hymenoptera, Formicidae, Leptanilloidinae

Directory of Open Access Journals (Sweden)

Marek Borowiec

2011-10-01

Full Text Available We describe three new species of the Neotropical ant genus Leptanilloides: L. gracilis sp. n. based on workers from Mexico and Guatemala, L. erinys sp. n. based on workers and a gyne from Ecuador, and L. femoralis sp. n. based on workers from Venezuela. The description of L. gracilis is a northern extension of the known range of the genus, now numbering eleven described species. We also describe and discuss three unassociated male morphotypes from Central America. We report the occurrence of a metatibial gland in Leptanilloides and a fused promesonotal connection (suture in some species. We provide a modified, detailed diagnosis of the genus and a revised key to the worker caste of the known species.

ESTIMATION OF THE TEMPERATURE RISE OF A MCU ACID STREAM PIPE IN NEAR PROXIMITY TO A SLUDGE STREAM PIPE

International Nuclear Information System (INIS)

Fondeur, F; Michael Poirier, M; Samuel Fink, S

2007-01-01

Effluent streams from the Modular Caustic-Side Solvent Extraction Unit (MCU) will transfer to the tank farms and to the Defense Waste Processing Facility (DWPF). These streams will contain entrained solvent. A significant portion of the Strip Effluent (SE) pipeline (i.e., acid stream containing Isopar(reg s ign) L residues) length is within one inch of a sludge stream. Personnel envisioned the sludge stream temperature may reach 100 C during operation. The nearby SE stream may receive heat from the sludge stream and reach temperatures that may lead to flammability issues once the contents of the SE stream discharge into a larger reservoir. To this end, personnel used correlations from the literature to estimate the maximum temperature rise the SE stream may experience if the nearby sludge stream reaches boiling temperature. Several calculation methods were used to determine the temperature rise of the SE stream. One method considered a heat balance equation under steady state that employed correlation functions to estimate heat transfer rate. This method showed the maximum temperature of the acid stream (SE) may exceed 45 C when the nearby sludge stream is 80 C or higher. A second method used an effectiveness calculation used to predict the heat transfer rate in single pass heat exchanger. By envisioning the acid and sludge pipes as a parallel flow pipe-to-pipe heat exchanger, this method provides a conservative estimation of the maximum temperature rise. Assuming the contact area (i.e., the area over which the heat transfer occurs) is the whole pipe area, the results found by this method nearly matched the results found with the previous calculation method. It is recommended that the sludge stream be maintained below 80 C to minimize a flammable vapor hazard from occurring

The genus Cecropia: a biological clock to estimate the age of recently disturbed areas in the Neotropics.

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Paul-Camilo Zalamea

Full Text Available Forest successional processes following disturbance take decades to play out, even in tropical forests. Nonetheless, records of vegetation change in this ecosystem are scarce, increasing the importance of the chronosequence approach to study forest recovery. However, this approach requires accurate dating of secondary forests, which until now was a difficult and/or expensive task. Cecropia is a widespread and abundant pioneer tree genus of the Neotropics. Here we propose and validate a rapid and straightforward method to estimate the age of secondary forest patches based on morphological observations of Cecropia trees. We found that Cecropia-inferred ages were highly correlated with known ages of the forest. We also demonstrate that Cecropia can be used to accurately date disturbances and propose twenty-one species distributed all over the geographical range of the genus as potential secondary forest chronometer species. Our method is limited in applicability by the maximal longevity of Cecropia individuals. Although the oldest chronosequence used in this study was 20 years old, we argue that at least for the first four decades after disturbance, the method described in this study provides very accurate estimations of secondary forest ages. The age of pioneer trees provides not only information needed to calculate the recovery of carbon stocks that would help to improve forest management, but also provides information needed to characterize the initial floristic composition and the rates of species remigration into secondary forest. Our contribution shows how successional studies can be reliably and inexpensively extended without the need to obtain forest ages based on expensive or potentially inaccurate data across the Neotropics.

Effect of anesthetic, tag size, and surgeon experience on postsurgical recovering after implantation of electronic tags in a neotropical fish: Prochilodus lineatus (Valenciennes, 1837 (Characiformes: Prochilodontidae

Directory of Open Access Journals (Sweden)

João M. Lopes

Full Text Available ABSTRACT Implantation of telemetry transmitters in fish can be affected by different parameters. This study aimed to evaluate the effect of type of anesthetic, tag size, and surgeon experience on surgical and postsurgical wound healing in the neotropical fish Prochilodus lineatus . In total, eighty fish were surgically implanted with telemetry transmitters and forty fish were kept as controls. Forty fish were implanted with a small tag and other forty were implanted with a large tag. Similarly, forty fish were anesthetized with eugenol and forty fish were anesthetized by electroanesthesia, and forty surgeries were performed by an expert surgeon and forty surgeries were performed by novice surgeons. At the end of the experimental period seventeen (21.3% tagged fish had postsurgical complications, including death (1.3%, tag expulsion (2.5%, antenna migration (2.5%, and infection (15%. Tag size was the key determinant for postsurgical complications. Surgical details and postsurgical wound healing were not affected by type of anesthetic. Incision size, duration of surgery, and wound area were significantly affected by tag size and surgeon experience, and the number of sutures was significantly affected by tag size only. The results indicate that successful implantation of telemetry transmitters is dependent upon surgeon experience and tag size.

Molecular data reveal complex hybridization and a cryptic species of neotropical wild cat.

Science.gov (United States)

Trigo, Tatiane C; Schneider, Alexsandra; de Oliveira, Tadeu G; Lehugeur, Livia M; Silveira, Leandro; Freitas, Thales R O; Eizirik, Eduardo

2013-12-16

Hybridization among animal species has recently become more recognized as an important phenomenon, especially in the context of recent radiations. Here we show that complex hybridization has led to contrasting patterns of genomic composition among closely related species of the Neotropical cat genus Leopardus. We show strong evidence of ancient hybridization and introgression between the pampas cat (L. colocolo) and northeastern populations of tigrina (L. tigrinus), leading to remarkable cytonuclear discordance in the latter. In contrast, southern tigrina populations show recent and continuing hybridization with Geoffroy's cat (L. geoffroyi), leading to extreme levels of interspecific admixture at their contact zone. Finally, we demonstrate that two seemingly continuous Brazilian tigrina populations show no evidence of ongoing gene flow between them, leading us to support their formal recognition as distinct species, namely L. tigrinus in the northeast and L. guttulus in the south. Copyright © 2013 Elsevier Ltd. All rights reserved.

On-stream chemical element monitor

International Nuclear Information System (INIS)

Averitt, O.R.; Dorsch, R.R.

1979-01-01

An apparatus and method for on-stream chemical element monitoring are described wherein a multiplicity of sample streams are flowed continuously through individual analytical cells and fluorescence analyses are performed on the sample streams in sequence, together with a method of controlling the time duration of each analysis as a function of the concomitant radiation exposure of a preselected perforate reference material interposed in the sample-radiation source path

Reconfigurable Multicore Architectures for Streaming Applications

NARCIS (Netherlands)

Smit, Gerardus Johannes Maria; Kokkeler, Andre B.J.; Rauwerda, G.K.; Jacobs, J.W.M.; Nicolescu, G.; Mosterman, P.J.

2009-01-01

This chapter addresses reconfigurable heterogenous and homogeneous multicore system-on-chip (SoC) platforms for streaming digital signal processing applications, also called DSP applications. In streaming DSP applications, computations can be specified as a data flow graph with streams of data items

Stretch-minimising stream surfaces

KAUST Repository

Barton, Michael; Kosinka, Jin; Calo, Victor M.

2015-01-01

We study the problem of finding stretch-minimising stream surfaces in a divergence-free vector field. These surfaces are generated by motions of seed curves that propagate through the field in a stretch minimising manner, i.e., they move without stretching or shrinking, preserving the length of their arbitrary arc. In general fields, such curves may not exist. How-ever, the divergence-free constraint gives rise to these 'stretch-free' curves that are locally arc-length preserving when infinitesimally propagated. Several families of stretch-free curves are identified and used as initial guesses for stream surface generation. These surfaces are subsequently globally optimised to obtain the best stretch-minimising stream surfaces in a given divergence-free vector field. Our algorithm was tested on benchmark datasets, proving its applicability to incompressible fluid flow simulations, where our stretch-minimising stream surfaces realistically reflect the flow of a flexible univariate object. © 2015 Elsevier Inc. All rights reserved.

Stretch-minimising stream surfaces

KAUST Repository

Barton, Michael

2015-05-01

We study the problem of finding stretch-minimising stream surfaces in a divergence-free vector field. These surfaces are generated by motions of seed curves that propagate through the field in a stretch minimising manner, i.e., they move without stretching or shrinking, preserving the length of their arbitrary arc. In general fields, such curves may not exist. How-ever, the divergence-free constraint gives rise to these \\'stretch-free\\' curves that are locally arc-length preserving when infinitesimally propagated. Several families of stretch-free curves are identified and used as initial guesses for stream surface generation. These surfaces are subsequently globally optimised to obtain the best stretch-minimising stream surfaces in a given divergence-free vector field. Our algorithm was tested on benchmark datasets, proving its applicability to incompressible fluid flow simulations, where our stretch-minimising stream surfaces realistically reflect the flow of a flexible univariate object. © 2015 Elsevier Inc. All rights reserved.

BLOSTREAM: A HIGH SPEED STREAM CIPHER

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ALI H. KASHMAR

2017-04-01

Full Text Available Although stream ciphers are widely utilized to encrypt sensitive data at fast speeds, security concerns have led to a shift from stream to block ciphers, judging that the current technology in stream cipher is inferior to the technology of block ciphers. This paper presents the design of an improved efficient and secure stream cipher called Blostream, which is more secure than conventional stream ciphers that use XOR for mixing. The proposed cipher comprises two major components: the Pseudo Random Number Generator (PRNG using the Rabbit algorithm and a nonlinear invertible round function (combiner for encryption and decryption. We evaluate its performance in terms of implementation and security, presenting advantages and disadvantages, comparison of the proposed cipher with similar systems and a statistical test for randomness. The analysis shows that the proposed cipher is more efficient, high speed, and secure than current conventional stream ciphers.

Removal of sulfur from process streams

International Nuclear Information System (INIS)

Brignac, D.G.

1984-01-01

A process wherein water is added to a non-reactive gas stream, preferably a hydrogen or hydrogen-containing gas stream, sufficient to raise the water level thereof to from about 0.2 percent to about 50 percent, based on the total volume of the process gas stream, and the said moist gas stream is contacted, at elevated temperature, with a particulate mass of a sulfur-bearing metal alumina spinel characterized by the formula MAl 2 O 4 , wherein M is chromium, iron, cobalt, nickel, copper, cadmium, mercury, or zinc to desorb sulfur thereon. In the sulfur sorption cycle, due to the simultaneous adsorption of water and sulfur, the useful life of the metal alumina spinel for sulfur adsorption can be extended, and the sorbent made more easily regenerable after contact with a sulfur-bearing gas stream, notably sulfur-bearing wet hydrogen or wet hydrogen-rich gas streams

StreamStats in Oklahoma - Drainage-Basin Characteristics and Peak-Flow Frequency Statistics for Ungaged Streams

Science.gov (United States)

Smith, S. Jerrod; Esralew, Rachel A.

2010-01-01

The USGS Streamflow Statistics (StreamStats) Program was created to make geographic information systems-based estimation of streamflow statistics easier, faster, and more consistent than previously used manual techniques. The StreamStats user interface is a map-based internet application that allows users to easily obtain streamflow statistics, basin characteristics, and other information for user-selected U.S. Geological Survey data-collection stations and ungaged sites of interest. The application relies on the data collected at U.S. Geological Survey streamflow-gaging stations, computer aided computations of drainage-basin characteristics, and published regression equations for several geographic regions comprising the United States. The StreamStats application interface allows the user to (1) obtain information on features in selected map layers, (2) delineate drainage basins for ungaged sites, (3) download drainage-basin polygons to a shapefile, (4) compute selected basin characteristics for delineated drainage basins, (5) estimate selected streamflow statistics for ungaged points on a stream, (6) print map views, (7) retrieve information for U.S. Geological Survey streamflow-gaging stations, and (8) get help on using StreamStats. StreamStats was designed for national application, with each state, territory, or group of states responsible for creating unique geospatial datasets and regression equations to compute selected streamflow statistics. With the cooperation of the Oklahoma Department of Transportation, StreamStats has been implemented for Oklahoma and is available at http://water.usgs.gov/osw/streamstats/. The Oklahoma StreamStats application covers 69 processed hydrologic units and most of the state of Oklahoma. Basin characteristics available for computation include contributing drainage area, contributing drainage area that is unregulated by Natural Resources Conservation Service floodwater retarding structures, mean-annual precipitation at the

Collaborative Media Streaming

OpenAIRE

Kahmann, Verena

2008-01-01

Mit Hilfe der IP-Technologie erbrachte Multimedia-Dienste wie IPTV oder Video-on-Demand sind zur Zeit ein gefragtes Thema. Technisch werden solche Dienste unter dem Begriff "Streaming" eingeordnet. Ein Server sendet Mediendaten kontinuierlich an Empfänger, welche die Daten sofort weiterverarbeiten und anzeigen. Über einen Rückkanal hat der Kunde die Möglichkeit der Einflussnahme auf die Wiedergabe. Eine Weiterentwicklung dieser Streaming-Dienste ist die Möglichkeit, gemeinsam mit anderen dens...

Motion of shocks through interplanetary streams

International Nuclear Information System (INIS)

Burlaga, L.F.; Scudder, J.D.

1975-01-01

A model for the motion of flare-generated shocks through interplanetary streams is presented, illustrating the effects of a stream-shock interaction on the shock strength and geometry. It is a gas dynamic calculation based on Whitham's method and on an empirical approximation for the relevant characteristics of streams. The results show that the Mach number of a shock can decrease appreciably to near unity in the interaction region ahead of streams and that the interaction of a spherically symmetric shock with a spiral-shaped corotating stream can cause significant distortions of the initial shock front geometry. The geometry of the February 15--16, 1967, shock discussed by Lepping and Chao (1972) is qualitatively explained by this model

Stream chemistry in the eastern United States. 2. Current sources of acidity in acidic and low acid-neutralizing-capacity streams

International Nuclear Information System (INIS)

Herlihy, A.T.; Kaufmann, P.R.; Mitch, M.E.

1991-01-01

The authors examined anion composition in National Stream Survey (NSS) data in order to evaluate the most probable sources of current acidity in acidic and low acid neutralizing capacity (ANC) streams in the eastern United States. Acidic streams that had almost no organic influence (less than 10% of total anions) and sulfate and nitrate concentrations indicative of evaporative concentration of atmospheric deposition were classified as acidic due to acidic deposition. These acidic streams were located in small forested watersheds in the Mid-Atlantic Highlands (an estimated 1950 km of stream length) and in the Mid-Atlantic Coastal Plain (1250 km). Acidic streams affected primarily by acidic deposition but also influenced by naturally occurring organic anions accounted for another 1180 km of acidic stream length and were located in the New Jersey Pine Barrens, plateau tops in the Mid-Atlantic and Southeast Highlands, and the Florida Panhandle. The total length of streams acidic due to acid mine drainage in the NSS (4590 km) was about the same as the total length of acidic streams likely affected by acidic deposition (4380 km). Acidic streams whose acid anion composition was dominated by organics were located in Florida and the Mid-Atlantic Coastal Plain. In Florida, most of the acidic streams were organic dominated, whereas about half of the streams in the Mid-Atlantic Coastal Plain were organic dominated. Organic-dominated acidic streams were not observed in the Mid-Atlantic and Southeast Highlands

The effect of in-stream activities on the Njoro River, Kenya. Part I: Stream flow and chemical water quality

Science.gov (United States)

Yillia, Paul T.; Kreuzinger, Norbert; Mathooko, Jude M.

For shallow streams in sub-Saharan Africa, in-stream activities could be described as the actions by people and livestock, which take place within or besides stream channels. This study examined the nature of in-stream activities along a rural stream in Kenya and established the inequality in water allocation for various livelihood needs, as well as the negative impact they have on dry weather stream flow and chemical water quality. Seven locations along the stream were studied in wet and dry weather of 2006. Enumeration consisted of making head counts of people and livestock and tallying visitors at hourly intervals from 6 a.m. to 7 p.m. To estimate water abstraction, filled containers of known volume were counted and the stream was sampled to examine the impact on water quality. Water samples were obtained upstream and downstream of in-stream activities before (6 a.m.) and during (11 a.m., 6 p.m.) activities. Samples were analyzed for suspended solids, turbidity, BOD 5, total nitrogen and total phosphorus. The daily total abstraction at the middle reaches during dry weather was 120-150 m 3 day -1. More than 60% of abstraction was done by water vendors. Vended water from the stream was sold at US 3.5-7.5 per m 3 and vendors earned between US 3-6 a day. Abstracted water contributed approximately 40-60% of the total daily consumptive water use in the riparian area during dry weather but >30% of the morning stream flow was abstracted thereby upsetting stream flow in the lower reaches. The daily total water abstraction correlated positively ( R2, 0.98) and significantly ( p < 0.05) with the daily total human visit, which was diurnally periodic with two peaks, occurring between 9 a.m. and 10 a.m. and from 4 p.m. to 5 p.m. This diurnal pattern of visits and the corresponding in-stream activities affected water quality. In particular, suspended solids, turbidity and BOD 5 levels increased significantly ( p < 0.05) downstream during in-stream activities. It was concluded

Stream Intermittency Sensors Monitor the Onset and Duration of Stream Flow Along a Channel Network During Storms

Science.gov (United States)

Jensen, C.; McGuire, K. J.

2017-12-01

Headwater streams are spatially extensive, accounting for a majority of global stream length, and supply downstream water bodies with water, sediment, organic matter, and pollutants. Much of this transmission occurs episodically during storms when stream flow and connectivity are high. Many headwaters are temporary streams that expand and contract in length in response to storms and seasonality. Understanding where and when streams carry flow is critical for conserving headwaters and protecting downstream water quality, but storm events are difficult to study in small catchments. The rise and fall of stream flow occurs rapidly in headwaters, making observation of the entire stream network difficult. Stream intermittency sensors that detect the presence or absence of water can reveal wetting and drying patterns over short time scales. We installed 50 intermittency sensors along the channel network of a small catchment (35 ha) in the Valley and Ridge of southwest Virginia. Previous work shows stream length is highly variable in this shale catchment, as the drainage density spans two orders of magnitude. The sensors record data every 15 minutes for one year to capture different seasons, antecedent moisture conditions, and precipitation rates. We seek to determine whether hysteresis between stream flow and network length occurs on the rising and falling limbs of events and if reach-scale characteristics such as valley width explain spatial patterns of flow duration. Our results indicate reaches with a wide, sediment-filled valley floor carry water for shorter periods of time than confined channel segments with steep valley side slopes. During earlier field mapping surveys, we only observed flow in a few of the tributaries for the wettest conditions mapped. The sensors now show that these tributaries flow more frequently during much smaller storms, but only for brief periods of time (hour). The high temporal sampling resolution of the sensors permits a more realistic

Electron cyclotron wave acceleration outside a flaring loop

Science.gov (United States)

Sprangle, P.; Vlahos, L.

1983-01-01

A model for the secondary acceleration of electrons outside a flaring loop is proposed. The results suggest that the narrow bandwidth radiation emitted by the unstable electron distribution inside a flaring loop can become the driver for secondary electron acceleration outside the loop. It is shown that a system of electrons gyrating about and streaming along an adiabatically spatially varying, static magnetic field can be efficiently accelerated to high energies by an electromagnetic wave propagating along and polarized transverse to the static magnetic field. The predictions from our model appear to be in general agreement with existing observations.

Electron cyclotron wave acceleration outside a flaring loop

International Nuclear Information System (INIS)

Sprangle, P.; Vlahos, L.

1983-01-01

We propose a model for the secondary acceleration of electrons outside a flaring loop. Our results suggest that the narrow bandwidth radiation emitted by the unstable electron distribution inside a flaring loop can become the driver for secondary electron acceleration outside the loop. We show that a system of electrons gyrating about and streaming along an adiabatically spatially varying, static magnetic field can be efficiently accelerated to high energies by an electromagnetic wave propagating along and polarized transverse to the static magnetic field. The predictions from our model appear to be in general agreement with existing observations

Energy from streaming current and potential

NARCIS (Netherlands)

Olthuis, Wouter; Schippers, Bob; Eijkel, Jan C.T.; van den Berg, Albert

2005-01-01

It is investigated how much energy can be delivered by a streaming current source. A streaming current and subsequent streaming potential originate when double layer charge is transported by hydrodynamic flow. Theory and a network model of such a source is presented and initial experimental results

Wadeable Streams Assessment Data

Science.gov (United States)

The Wadeable Streams Assessment (WSA) is a first-ever statistically-valid survey of the biological condition of small streams throughout the U.S. The U.S. Environmental Protection Agency (EPA) worked with the states to conduct the assessment in 2004-2005. Data for each parameter sampled in the Wadeable Streams Assessment (WSA) are available for downloading in a series of files as comma separated values (*.csv). Each *.csv data file has a companion text file (*.txt) that lists a dataset label and individual descriptions for each variable. Users should view the *.txt files first to help guide their understanding and use of the data.

Industrial-Strength Streaming Video.

Science.gov (United States)

Avgerakis, George; Waring, Becky

1997-01-01

Corporate training, financial services, entertainment, and education are among the top applications for streaming video servers, which send video to the desktop without downloading the whole file to the hard disk, saving time and eliminating copyrights questions. Examines streaming video technology, lists ten tips for better net video, and ranks…

Electron plasma oscillations at arbitrary Debye lengths

International Nuclear Information System (INIS)

Lehnert, B.

1990-12-01

A solution is presented for electron plasma oscillation in a thermalized homogeneous plasma, at arbitrary ratios between the Debye length λ D and the perturbation wave length λ. The limit λ D D >> λ corresponds to the free-streaming limit of strong kinetic phase-mixing due to large particle excursions. A strong large Debye distance (LDD) effect already appears when λ D > approx λ. The initial amplitude of the fluid-like contribution to the macroscopic density perturbation then becomes small as compared to the contribution from the free-streaming part. As a consequence, only a small fraction of the density perturbation remains after a limited number of kinetic damping times of the free-streaming part. The analysis further shows that a representation in terms of normal model of the form exp(-iωt) leads to amplitude factors of these modes which are related to each other and which depend on the combined free-streaming and fluid behaviour of the plasma. Consequently, these modes are coupled and cannot be treated as being independent of each other. (au)

First record of the genus Myllaena Erichson from Brazil, description of a new species and annotated catalog of Myllaena species from the Neotropical region (Coleoptera, Staphylinidae, Aleocharinae Primeiro registro do gênero Myllaena Erichson no Brasil, descrição de uma nova espécie e catálogo comentado das espécies de Myllaena da região Neotropical (Coleoptera, Staphylinidae, Aleocharinae

Directory of Open Access Journals (Sweden)

Edilson Caron

2008-09-01

Full Text Available The genus Myllaena Erichson, 1837, of the tribe Myllaenini Ganglbauer, 1895, is recorded from Brazil for the first time. A new species, Myllaena brasiliensis sp. nov., is described and illustrated; it is closely related to the insomnis species group, described from the Nearctic region. A short diagnosis of the genus and an annotated catalog of Myllaena species from the Neotropical region are also provided.O gênero Myllaena Erichson, 1837, da tribo Myllaenini Ganglbauer, 1895, é registrado pela primeira vez no Brasil. Uma nova espécie, Myllaena brasiliensis sp. nov., é descrita e ilustrada; esta espécie é proximamente relacionada ao grupo de espécies insomnis, descritas da região Neártica. Uma breve diagnose do gênero e um catálogo comentado das espécies de Myllaena da região Neotropical são também fornecidos.

Nutrient spiraling in streams and river networks

Science.gov (United States)

Ensign, Scott H.; Doyle, Martin W.

2006-12-01

Over the past 3 decades, nutrient spiraling has become a unifying paradigm for stream biogeochemical research. This paper presents (1) a quantitative synthesis of the nutrient spiraling literature and (2) application of these data to elucidate trends in nutrient spiraling within stream networks. Results are based on 404 individual experiments on ammonium (NH4), nitrate (NO3), and phosphate (PO4) from 52 published studies. Sixty-nine percent of the experiments were performed in first- and second-order streams, and 31% were performed in third- to fifth-order streams. Uptake lengths, Sw, of NH4 (median = 86 m) and PO4 (median = 96 m) were significantly different (α = 0.05) than NO3 (median = 236 m). Areal uptake rates of NH4 (median = 28 μg m-2 min-1) were significantly different than NO3 and PO4 (median = 15 and 14 μg m-2 min-1, respectively). There were significant differences among NH4, NO3, and PO4 uptake velocity (median = 5, 1, and 2 mm min-1, respectively). Correlation analysis results were equivocal on the effect of transient storage on nutrient spiraling. Application of these data to a stream network model showed that recycling (defined here as stream length ÷ Sw) of NH4 and NO3 generally increased with stream order, while PO4 recycling remained constant along a first- to fifth-order stream gradient. Within this hypothetical stream network, cumulative NH4 uptake decreased slightly with stream order, while cumulative NO3 and PO4 uptake increased with stream order. These data suggest the importance of larger rivers to nutrient spiraling and the need to consider how stream networks affect nutrient flux between terrestrial and marine ecosystems.

Stream Lifetimes Against Planetary Encounters

Science.gov (United States)

Valsecchi, G. B.; Lega, E.; Froeschle, Cl.

2011-01-01

We study, both analytically and numerically, the perturbation induced by an encounter with a planet on a meteoroid stream. Our analytical tool is the extension of pik s theory of close encounters, that we apply to streams described by geocentric variables. The resulting formulae are used to compute the rate at which a stream is dispersed by planetary encounters into the sporadic background. We have verified the accuracy of the analytical model using a numerical test.

Electron Fluid Description of Wave-Particle Interactions in Strong Buneman Turbulence

Science.gov (United States)

Che, Haihong

2013-10-01

To understand the nature of anomalous resistivity in magnetic reconnection, we investigate turbulence-induced momentum transport and energy dissipation associated with electron heating in Buneman instability. Using 3D particle-in-cell simulations, we find that the macroscopic effects generated by wave-particle interactions can be described by a set of electron fluid equations. These equations show that the energy dissipation and momentum transports in Buneman instability are locally quasi-static but globally non-static and irreversible. Turbulence drag dissipates both the bulk energy of electron streams and the associated magnetic energy. The decrease of magnetic field maintains an inductive electric field that re-accelerates electrons. The net loss of streaming energy is converted into electron heat and increases the electron Boltzmann entropy. The growth of self-sustained Buneman waves satisfies a Bernoulli-like equation which relates the turbulence-induced convective momentum transport and thermal momentum transport. Electron trapping and de-trapping drives local momentum transports, while phase mixing converts convective momentum into thermal momentum.These two local momentum transports sustain the Buneman waves and act as the micro-macro link in the anomalous heating process. This research is supported by the NASA Postdoctoral Program at NASA/GSFC administered by Oak Ridge Associated Universities through a contract with NASA.

The genera Cosmopterix Hübner and Pebobs Hodges in the New World with special attention to the Neotropical fauna (Lepidoptera: Cosmopterigidae)

OpenAIRE

Koster, J.C.

2010-01-01

The genera Cosmopterix Hübner, [1825] and Pebobs Hodges, 1978 (Cosmopterigidae) of the New World are revised, for the Neotropical fauna for the first time. A total of 102 species is recognized and 49 species are described as new: Cosmopterix adrastea spec. nov., C. amalthea spec. nov., C. ananke spec. nov., C. argentifera spec. nov., C. aurotegulae spec. nov., C. beckeri spec. nov., C. callisto spec. nov., C. carpo spec. nov., C. chaldene spec. nov., C. chalupae spec. nov., C. erinome spec. n...

THE PAL 5 STAR STREAM GAPS

International Nuclear Information System (INIS)

Carlberg, R. G.; Hetherington, Nathan; Grillmair, C. J.

2012-01-01

Pal 5 is a low-mass, low-velocity-dispersion, globular cluster with spectacular tidal tails. We use the Sloan Digital Sky Survey Data Release 8 data to extend the density measurements of the trailing star stream to 23 deg distance from the cluster, at which point the stream runs off the edge of the available sky coverage. The size and the number of gaps in the stream are measured using a filter which approximates the structure of the gaps found in stream simulations. We find 5 gaps that are at least 99% confidence detections with about a dozen gaps at 90% confidence. The statistical significance of a gap is estimated using bootstrap resampling of the control regions on either side of the stream. The density minimum closest to the cluster is likely the result of the epicyclic orbits of the tidal outflow and has been discounted. To create the number of 99% confidence gaps per unit length at the mean age of the stream requires a halo population of nearly a thousand dark matter sub-halos with peak circular velocities above 1 km s –1 within 30 kpc of the galactic center. These numbers are a factor of about three below cold stream simulation at this sub-halo mass or velocity but, given the uncertainties in both measurement and more realistic warm stream modeling, are in substantial agreement with the LCDM prediction.

Fish populations in Plynlimon streams

Directory of Open Access Journals (Sweden)

D. T. Crisp

1997-01-01

Full Text Available In Plynlimon streams, brown trout (Salmo trutta L. are widespread in the upper Wye at population densities of 0.03 to 0.32 fish m-2 and show evidence of successful recruitment in most years. In the upper Severn, brown trout are found only in an area of c. 1670 -2 downstream of Blaenhafren Falls at densities of 0.03 to 0.24 fish -2 and the evidence suggests very variable year to year success in recruitment (Crisp & Beaumont, 1996. Analyses of the data show that temperature differences between afforested and unafforested streams may affect the rates of trout incubation and growth but are not likely to influence species survival. Simple analyses of stream discharge data suggest, but do not prove, that good years for recruitment in the Hafren population were years of low stream discharge. This may be linked to groundwater inputs detected in other studies in this stream. More research is needed to explain the survival of the apparently isolated trout population in the Hafren.

Stream Response to an Extreme Defoliation Event

Science.gov (United States)

Gold, A.; Loffredo, J.; Addy, K.; Bernhardt, E. S.; Berdanier, A. B.; Schroth, A. W.; Inamdar, S. P.; Bowden, W. B.