Vector Dispersion Research Articles

Respuesta doméstica a las recomendaciones sanitarias de intervención sobre ambiente y perros en una localidad con transmisión de leishmaniasis visceral (Pto. Iguazú, Argentina, 2014–2016)

Introduction: Visceral leishmaniasis (VL) is an emerging parasitic disease in Argentina. In Puerto Iguazu, border with Brazil and Paraguay, vector and canine cases were registered in 2010; and in 2014 and 2015 there were two human cases. Objective: The objective of this article is to analyze changes at the micro-scale level after informing the cohabitants of the diagnosis of canine LV (LVC), letting them know the environmental management strategies to reduce contact with the vector. Method: It is a descriptive researh, which investigated in two moments (2014 and 2016) a non-probabilistic sample distributed based on the criterion of the best scenario for the presence of the vector (n = 55). Sampling points with the presence of vectors and at least one dog with LVC (n = 6/55) were selected, after a first entomological and veterinary diagnosis raking. Results: A single household implemented the suggested modifications. The changes were not enough to control the transmission. The hypothesis is that the control measures require intervention at a meso-scale (the neighborhood instead of the home), taking into account the real radius of vector dispersion. Conclusions: The risk of human infection due to VL is related to the way of life, including interspecies relationships. The human-dog relationships combine speciesism and post-humanism, which limits the effectiveness of “responsible ownership” as model of a healthy bond.

Correction: Cost and time-effective method for multi-scale measures of rugosity, fractal dimension, and vector dispersion from coral reef 3D models.

[This corrects the article DOI: 10.1371/journal.pone.0175341.].

Indicadores socioambientais de focos do Aedes aegypti no extremo sul de Santa Catarina

Esta pesquisa analisou a distribuição espacial de focos do Aedes aegypti encontrados em 2016 na área de abrangência da Associação de Munícipios do Extremo Sul Catarinense (AMESC) e comparou com indicadores socioambientais (precipitação, temperatura, saneamento básico e população). Todos os dados são secundários, disponibilizados por diferentes órgãos governamentais. Foram observados 44 focos distribuídos em 6 municípios, sendo que o município Passo de Torres concentrou 61% desses focos. Esta cidade faz fronteira com o Estado do Rio Grande do Sul, região afetada, e, assim como os demais municípios com alto índice de infestação, é atravessada longitudinalmente pela BR-101. Isto pode indicar que a BR-101 é o principal meio de dispersão do vetor. Há maior ocorrência do vetor nas estações mais quentes (verão e outono), entretanto, não foi observada correlação com a precipitação, ainda que em 2016 esta superou a média histórica da região. Apesar da boa cobertura do abastecimento de água, não há dados sobre resíduos, tampouco sobre o esgotamento na região. Assim, a indisponibilidade de dados específicos de saneamento prejudicou uma análise detalhada de aspectos relacionados a esse indicador. Embora estas informações possam ser utilizadas pelos gestores públicos para definição de diretrizes de combate ao mosquito, são necessárias maiores complementações em nível local.

A New View of Long-Term Geomagnetic Field Secular Variation

This study carries out a statistical analysis of high-resolution PSV records for the last ~70 ka from three different regions of the Earth. We consider directional and intensity variability in each region on time scales of 103-105 years in order to evaluate long-term PSV. We then compare those results with more traditional long-term PSV statistical studies averaged over ~106 years. Three replicate PSV records from one region (subtropical North Atlantic Ocean) were averaged at overlapping 3ka and 9 ka intervals. Variability in both scalar inclination and declination variability and vector angular dispersion are significant and coherent among the three records. The vector dispersion is relatively low for most of the time but contains two relatively narrow intervals (~30-42 ka and 60-65 ka) of high dispersion. (Vector dispersion in all records was calculated after removing directions with true excursional VGPs, VGPs < 45° N.) We have carried out a comparable statistical analysis on two other PSV records from other parts of the Earth (Chile margin; Philippines/Indonesia). The results for these three regions are comparable in their overall style of variability. The scalar directional variability from the Philippines/Indonesia is quite different in detail from the other two regions, as might be expected, but the scalar directional variability between the Western Hemisphere regions is remarkably consistent considering their distance from one another. This may be associated with them being on the same longitude swath and having some coherent dynamo activity occurring along that path. Three magnetic field excursions occur in the study interval. All three excursions are associated with the two highest vector dispersion intervals. Paleointensity records from the three regions were subjected to the same statistical analysis as the directions. These records are allso coherent in their pattern of variability. The similarity in paleointensity variability on a global scale is expected even though the detailed scalar directional variability is not coherent on a global scale. The pattern of intensity variability is strongly correlated with the pattern of vector dispersion and excursions on a global scale – high (low) intensity is associated with low (high plus excursions) vector dispersion.

Natural Infection of Phlebotomus sergenti by Leishmania tropica in Libya.

Cutaneous Leishmaniasis (CL) is a public health concern caused by Leishmania (L.) major and L.tropica in Libya. Information on sandfly vectors, as well as their associated Leishmania species, is of paramount importance because vector dispersion is one of the major factors responsible for pathogen dissemination. A number of 515 sandflies (275 males and 240 females) were collected during June-November 2012 using the Centers for Disease Control miniature light traps from Al Rabta, northwest of Libya. Two hundred and forty unfed females were identified; Phlebotomus (Ph.) papatasi (N = 97), Ph. sergenti (N = 27), Ph. longicuspis (N = 32), Sergentomyia (Se.) minuta (N = 38), and Se. fallax (N = 46). These flies were screened for Leishmania DNA using the polymerase chain reaction-restriction fragment length polymorphism analysis of the internal transcribed spacer 1 and sequencing. Two Ph. sergenti were found positive to L. tropica DNA. This finding should be considered for any further vector surveillance and epidemiological studies of CL in endemic areas across Libya.

Vector-borne diseases and climate change: a European perspective.

Climate change has already impacted the transmission of a wide range of vector-borne diseases in Europe, and it will continue to do so in the coming decades. Climate change has been implicated in the observed shift of ticks to elevated altitudes and latitudes, notably including the Ixodes ricinus tick species that is a vector for Lyme borreliosis and tick-borne encephalitis. Climate change is also thought to have been a factor in the expansion of other important disease vectors in Europe: Aedes albopictus (the Asian tiger mosquito), which transmits diseases such as Zika, dengue and chikungunya, and Phlebotomus sandfly species, which transmits diseases including Leishmaniasis. In addition, highly elevated temperatures in the summer of 2010 have been associated with an epidemic of West Nile Fever in Southeast Europe and subsequent outbreaks have been linked to summer temperature anomalies. Future climate-sensitive health impacts are challenging to project quantitatively, in part due to the intricate interplay between non-climatic and climatic drivers, weather-sensitive pathogens and climate-change adaptation. Moreover, globalisation and international air travel contribute to pathogen and vector dispersion internationally. Nevertheless, monitoring forecasts of meteorological conditions can help detect epidemic precursors of vector-borne disease outbreaks and serve as early warning systems for risk reduction.

Dynamic correlations in the highly dilute 2D electron liquid: Loss function, critical wave vector and analytic plasmon dispersion

Correlations, highly important in low–dimensional systems, are known to decrease the plasmon dispersion of two–dimensional electron liquids. Here we calculate the plasmon properties, applying the ‘Dynamic Many-Body Theory’, accounting for correlated two–particle–two–hole fluctuations. These dynamic correlations are found to significantly lower the plasmon’s energy. For the data obtained numerically, we provide an analytic expression that is valid across a wide range both of densities and of wave vectors. Finally, we demonstrate how this can be invoked in determining the actual electron densities from measurements on an AlGaAs quantum well.

The Evolutionary History and Spatiotemporal Dynamics of the NC Lineage of Citrus Tristeza Virus.

Citrus tristeza virus (CTV) is a major pathogen affecting citrus trees worldwide. However, few studies have focused on CTV’s evolutionary history and geographic behavior. CTV is locally dispersed by an aphid vector and long distance dispersion due to transportation of contaminated material. With the aim to delve deeper into the CTV-NC (New Clade) genotype evolution, we estimated an evolution rate of 1.19 × 10−3 subs/site/year and the most common recent ancestor in 1977. Furthermore, the place of origin of the genotype was in the United States, and a great expansion of the population was observed in Uruguay. This expansion phase could be a consequence of the increment in the number of naïve citrus trees in Uruguayan orchards encompassing citrus industry growth in the past years.

Knowledge-based wideband radar target detection in the heterogeneous environment

In this paper, we address wideband radar target detection in the heterogeneous environment. Firstly, a linear model of the wideband radar target return with the steering vector dispersion is established. Secondly, the heterogeneous clutter is modeled as a two-dimensional wide-sense stationary (WSS) process with inverse complex Wishart distributed random covariance matrices in the time-space and frequency domain. Then, several generalized likelihood ratio test (GLRT) based detectors are designed, some of which integrate the prior knowledge of the clutter covariance matrix with the Bayesian approach, while the others are with the heuristic approach. Finally, the performance of the detectors is evaluated by simulations, and the results show that the detectors based on the Bayesian approach outperform the other detectors.

First Report on Natural Infection of Phlebotomus sergenti with Leishmania tropica in a Classical Focus of Leishmania major in Tunisia.

In Tunisia, chronic cutaneous leishmaniasis due to Leishmania tropica is an important health problem. Its spreading has not been fully elucidated. Information on sandfly vectors, as well as their associated Leishmania species, is of paramount importance since vector dispersion is one of the major factors responsible for pathogen dissemination. Ninety-seven unfed females belonging to the genera Sergentomyia and Phlebotomus were collected between June and August 2015 using sticky paper traps. Polymerase chain reaction-restriction fragment length polymorphism analysis of the internal transcribed spacer 1and sequencing were used for Leishmania detection and identification. In total, 650 sandflies were captured and identified (380 males and 270 females). Ninety-seven unfed females were tested for the presence of Leishmania parasite DNA. Six Phlebotomus sergenti were found positive for L. tropica. This novel finding enhances the understanding of the cycle extension of L. tropica outside its original focus of Tataouine.

Cost and time-effective method for multi-scale measures of rugosity, fractal dimension, and vector dispersion from coral reef 3D models.

We present a method to construct and analyse 3D models of underwater scenes using a single cost-effective camera on a standard laptop with (a) free or low-cost software, (b) no computer programming ability, and (c) minimal man hours for both filming and analysis. This study focuses on four key structural complexity metrics: point-to-point distances, linear rugosity (R), fractal dimension (D), and vector dispersion (1/k). We present the first assessment of accuracy and precision of structure-from-motion (SfM) 3D models from an uncalibrated GoPro™ camera at a small scale (4 m2) and show that they can provide meaningful, ecologically relevant results. Models had root mean square errors of 1.48 cm in X-Y and 1.35 in Z, and accuracies of 86.8% (R), 99.6% (D at scales 30–60 cm), 93.6% (D at scales 1–5 cm), and 86.9 (1/k). Values of R were compared to in-situ chain-and-tape measurements, while values of D and 1/k were compared with ground truths from 3D printed objects modelled underwater. All metrics varied less than 3% between independently rendered models. We thereby improve and rigorously validate a tool for ecologists to non-invasively quantify coral reef structural complexity with a variety of multi-scale metrics.

Risk analysis and prediction of visceral leishmaniasis dispersion in São Paulo State, Brazil.

Visceral leishmaniasis (VL) is an important neglected disease caused by a protozoan parasite, and represents a serious public health problem in many parts of the world. It is zoonotic in Europe and Latin America, where infected dogs constitute the main domestic reservoir for the parasite and play a key role in VL transmission to humans. In Brazil this disease is caused by the protozoan Leishmania infantum chagasi, and is transmitted by the sand fly Lutzomyia longipalpis. Despite programs aimed at eliminating infection sources, the disease continues to spread throughout the Country. VL in São Paulo State, Brazil, first appeared in the northwestern region, spreading in a southeasterly direction over time. We integrate data on the VL vector, infected dogs and infected human dispersion from 1999 to 2013 through an innovative spatial temporal Bayesian model in conjunction with geographic information system. This model is used to infer the drivers of the invasion process and predict the future progression of VL through the State. We found that vector dispersion was influenced by vector presence in nearby municipalities at the previous time step, proximity to the Bolívia-Brazil gas pipeline, and high temperatures (i.e., annual average between 20 and 23°C). Key factors affecting infected dog dispersion included proximity to the Marechal Rondon Highway, high temperatures, and presence of the competent vector within the same municipality. Finally, vector presence, presence of infected dogs, and rainfall (approx. 270 to 540mm/year) drove the dispersion of human VL cases. Surprisingly, economic factors exhibited no noticeable influence on disease dispersion. Based on these drivers and stochastic simulations, we identified which municipalities are most likely to be invaded by vectors and infected hosts in the future. Prioritizing prevention and control strategies within the identified municipalities may help halt the spread of VL while reducing monitoring costs. Our results contribute important knowledge to public and animal health policy planning, and suggest that prevention and control strategies should focus on vector control and on blocking contact between vectors and hosts in the priority areas identified to be at risk.

초기 산사태 위험도 구축을 위한 지형요소의 활용

토석류를 포함하는 산사태 재해는 빠른 이동속도로 인한 대응 및 대피가 어려운 특성으로 인해 발생 초기에 그 위험성을 파악, 예방대책을 수립하는 것이 무엇보다 필요하다 할 수 있다. 하지만 현재까지 다양한 방법들이 초기 산사태 재해의 발생 및 위험도를 파악하기 위해 활용되었으나, 분석과정과 입력변수의 복잡함, 그리고 이로 인한 모델의 단순화로 인해 산정된 산사태 위험도의 정확성에는 많은 의문이 제기되고 있는 실정이다. 이에 본 연구는 산사태 재해예방을 목적으로 실제 지형의 특성을 파악, 이를 초기 산사태 위험도 평가에 적용하는 방안에 대해 알아보고자 하였다. 지형특성 분석을 위해 방향성 벡터의 통계적 방법을 이용한 벡터분산(vector dispersion)과 평면도(planarity) 기법을 이용, 지형특성과 산사태 위험도간의 상관관계를 규명하고자 하였다. 분석결과는 제안한 두 방법 모두 초기 산사태 위험도 분석에 있어 매우 효과적인 것으로 나타났다. 결국, 지형특성은 산사태 위험도에 영향을 미치고 있으며, 보다 객관적인 산사태 위험성 평가를 수행하기 위해서는 개별 모형보다는 다수의 모형을 이용, 각각의 장점을 극대화할 필요가 있다. 이는 결국 산사태의 발생이 단순한 특정 요소만으로 결정되는 것이 아니며, 내 · 외부적인 요인들간의 상호작용에 의해 유발되는 복합적인 자연현상임을 인지하고 보다 다양한 방법들을 통해 산사태 발생 메커니즘에 대한 추가적인 연구가 수행되어야 할 것이다.

Highly PEGylated DNA Nanoparticles Provide Uniform and Widespread Gene Transfer in the Brain.

Gene delivery to the central nervous system (CNS) has potential as a means for treating numerous debilitating neurological diseases. Nonviral gene vector platforms are tailorable and can overcome key limitations intrinsic to virus-mediated delivery; however, lack of clinical efficacy with nonviral systems to date may be attributed to limited gene vector dispersion and transfection in vivo. It is shown that the brain extracellular matrix (ECM) strongly limits penetration of polymer-based gene vector nanoparticles (NP) through the brain parenchyma, even when they are very small (<60 nm) and coated with a polyethylene glycol (PEG) corona of typical density. Following convection enhanced delivery (CED), conventional gene vectors are confined to the injection site, presumably by adhesive interactions with the brain ECM and do not provide gene expression beyond the point of administration. In contrast, it is found that incorporating highly PEGylated polymers allows the production of compacted (≈43 nm) and colloidally stable DNA NP that avoid adhesive trapping within the brain parenchyma. When administered by CED into the rat striatum, highly PEGylated DNA NP distribute throughout and provide broad transgene expression without vector-induced toxicity. The use of these brain-penetrating gene vectors, in conjunction with CED, offers an avenue to improve gene therapy for CNS diseases.

지형특성을 활용한 산사태 위험도 판단을 위한 비교

토석류를 포함하는 산사태 재해는 우리나라에서 그 발생빈도가 상대적으로 큰 자연재해 중 하나이며 이로 인한 인명 및 재산피해는 매년 증가하고 있다. 이에 정부에서는 사면재해 대응 및 예방을 위한 다양한 방지대책을 추진하고 있으나, 대부분 재해발생 이후 발생지역을 중심으로 복구대책을 수립하는 것이 대부분이라 실질적인 국민의 생명과 재산을 보호하는 예방대책이라고 보기는 어렵다. 이에 본 연구는 산사태 재해 예방을 목적으로 실제 지형의 특성을 파악, 이를 위험도 평가에 활용하는 방안에 대해 알아보고자 하였다. 지형특성 분석을 위해 SINMAP(Stability INdex MAPping)과 통계적 기법인 벡터 분산을 활용하였으며 이를 실제 산사태 발생현장에 적용, 지형특성과 산사태와의 관계를 규명하고자 하였다. 분석결과는 제안한 두 가지 기법이 동일하게 위험도가 높다고 평가한 지역에서는 산사태 위험도가 상대적으로 높게 산정되었다. 이는 본 연구에서 제시한 방법이 지형특성과 산사태 위험도와의 관계성 규명에 있어 합리적임을 보여준다고 할 수 있다. 또한 실제 현장조사 결과와 비교한 산사태 위험도는 SINMAP 기법이 토석류와 같은 연속성 산사태에 있어 보다 정확하게 판단되었으나 특정요소의 위험성을 구체적으로 고려할 수 있는 기법을 추가적으로 고려한다면 보다 정확한 산사태 위험을 평가할 수 있을 것으로 사료된다. Landslide disasters including debris flows are the one of the most frequent natural disasters in Korea, and losses of lives and property damages due to these catastrophic events have been increased every year. Various mitigation programs and related policies have been conducted in order to respond and prepare landslide disasters. Most landslide reduction programs are, however, focused on recovery actions after the disasters and lead to unrealistic consequences to the affected people and their properties. The main objective of this study, therefore, is to evaluate the landslide hazard based on the identification of geomorphological features, which is for the preparedness of the landslide disasters. Two methodologies, SINMAP and vector dispersion analyses are used to simulate those characteristics where landslides are actually located. Results showed that both methods well discriminate geomorphic features between stable and unstable domains. This proves that geomorphological characteristics well describe a relationship with the existing landslide hazard. SINMAP analysis which is based on the consecutive model considering external factors like infiltration is well identify the landslide hazard especially for debris flow type landslides rather than vector dispersion focusing on a specific area. Combining with other methods focusing specific characteristics of geomorphological feature, accurate landslide hazard assessments are implemented.

Occurrence of Aedes aegypti (Diptera, Culicidae) in a Dengue Transmission Area at Coastal Maranhão State, Brazil

This study aimed to estimate the occurrence of Aedes aegypti adults at distinct climatic seasons at neighbor- hoods from the municipality of Sao Luis, Maranhao State, Brazil, as well as to verify the presence of Dengue virus (DENV) in the specimens collected. A total of 320 properties were visited in eight neighborhoods that were previously randomly chosen. Samplings were made at three periods: dry season/2008, rainy season/2009 and dry season/2009. A to- tal of 563 Ae. aegypti mosquitoes were collected, with 141 of them collected during dry season/2008, 272 during rainy season/2009 and the remnant, during dry season/2009. Specimen were divided into lots and subjected to RT-semi-nested- PCR analysis and virus isolation was carried out using cell culture (C6/36 clone) of Ae. albopictus. The number of adults significantly varied at the neighborhoods of Coreia de Baixo, Lira, Joao Paulo, and Conjunto Cohatrac I. Molecular anal- yses of specimens showed no positivity for DENV. At the municipality of Sao Luis, seasonal climate variation might in- fluence the density of Ae. aegypti adults, however, other factors such as population density, sanitation conditions, and the presence of mosquito breeding sites ought to be assessed as important parameters influencing vector dispersion.

Cross scatter-combir of the six-port transducer of vector network analyzer

Two designs of 12-pole measuring converters were studied in the paper, in which the E-plane waveguide X-shaped power divider and four directional detectors are used. In the first converter design, the X-shaped divider is loaded in a measuring port directly on the studied two-pole network, and three scalar panoramas measure the reflection coefficient and two attenuation coefficients. The basic parameters of the mathematical model allow realizing the advantages of the six-port converter. The main source of the measurement error refers to the “operation” of scalar panorama, located in the input port of the divider, in a standing wave mode. The constructed mathematical model reflects the properties of magnetic Hertz vector dispersion over a scalar four-port discontinuity of the divider. In the second converter design, the supporting directional detector is replaced from the input port to the measuring channel between the divider discontinuity and studied two-pole network, and adjusted to the output wave power. In the mathematical model of the six-port converter there are no re-reflections which arise in the measuring port; though the centers of three circles on a geometrical model lie on the same line that is the lack of this design. The obtained mathematical model of the converter corresponds to the model of the converter-summer of the input wave. As can be seen from the conducted experimental studies, the error of measurement of the complex reflection coefficient of two designs of vector panoramas is at the level of 10%.

Morphological Tuning of the Plasmon Dispersion Relation in Dielectric-Loaded Nanofiber Waveguides

Understanding the impact of lateral mode confinement in plasmonic waveguides is of fundamental interest regarding potential applications in plasmonic devices. The knowledge of the frequency-wave vector dispersion relation provides the full information on electromagnetic field propagation in a waveguide. This Letter reports on the measurement of the real part of the surface plasmon polariton dispersion relation in the near infrared spectral regime for individual nanoscale plasmonic waveguides, which were formed by deposition of para-hexaphenylene (p-6P) based nanofibers on top of a gold film. A detailed structural characterization of the nanofibers provides accurate information on the dimensions of the investigated waveguides and enables us to quantify the effect of mode confinement by comparison with experimental results from continuous p-6P films and calculations based on the effective index method.

Determining the Thickness of Pb Film Similar to Bulk with Energy Dispersion Derived from Quantum Well States

It is known that the energy spacing between adjacent empty quantum well (QW) states in Pb islands on Cu(111) would reveal the shrinking characteristic originating from the effect of the image potential. Using the phase accumulation model, including a phase factor contributed from the image potential, the shrinking energy spacing can be quantitatively explained with the assumption of the parabolic energy versus wave vector (E–k) dispersion. However, an experimental dispersion acquired from analyzing the energies of the QW state reveals a linear E–k relationship corresponding to the Pb bulk band structure, implying the assumed parabolic dispersion is not appropriate. By combining the linear dispersion with the image potential effect in the calculation, it is found that the calculated values of energy spacing of island thickness below eight atomic layers are not in agreement with the experimental measurements. This implies that the electronic structure of Pb islands would be similar to that of the bulk when their thicknesses reach eight-atomic layers.

Dispersion of the mechanical parts performance indicators based on the concept of random vector

To solve the precision and reliability problem of various machinery equipments and military vehicles, some military organisations, the industrial sector and the academia at home and abroad begin to pay attention to the statistical distribution of machining dimensions, material properties and service loads, and the system reliability optimization design with constraints and reliability optimization design of various mechanical parts is studied in this way. However, the above researches focus on solving the strength and the life problem, and no studies have been done on the discrete degree and discrete pattern of other performance indicators. The concept of using a random vector to describe the mechanical parts performance indicators is presented; characteristics between the value of the vector variance matrix determinant and the sum of the diagonal covariance matrix in describing the performance indicators of vector dispersion are studied and compared. A clutch diaphragm spring is set as an example, the geometric dimension indicator is described with random vector, and the applicability of using variance matrix determinant and variance matrix trace of geometric dimension vector to describe discrete degree of random vector is studied by using Monte-Carlo simulation method and component discrete degree perturbation method. Also, the effects of different components of diaphragm spring geometric dimension vector on the value of covariance matrix determinant and the sum of covariance matrix diagonal of diaphragm spring performance indicators vector are analyzed. The present study shows that the impacts of the dispersion of diaphragm spring cone angle on every performance dispersion are all ranked first, and far exceed that of other dimension dispersion. So it must be strictly controlled in the production process. The result of the research work provides a reference for the design of diaphragm spring, and also it presents a proper method for researching the performance of other mechanical parts.