2,834 research outputs found
Mosquito Larvicidal Constituents from Lantana Viburnoides SP Viburnoides Var Kisi (A. rich) Verdc (Verbenaceae).
\ud
\ud
Lantana viburnoides sp viburnoides var kisi is used in Tanzania ethnobotanically to repel mosquitoes as well as in traditional medicine for stomach ache relief. Bioassay-guided fractionation and subtraction bioassays of the dichloromethane extract of the root barks were carried out in order to identify the bioactive components for controlling Anopheles gambiae s.s. mosquito larvae. Twenty late III or early IV instar larvae of An. gambiae s.s. were exposed to various concentrations of the plant extracts, fractions, blends and pure compounds, and were assayed in the laboratory by using the protocol of WHO 1996. Mean mortalities were compared using Dunnett's test (p < 0.05) and lethal concentration calculated by Lackfit Inversel of the SAS programme. The crude extract (LC50 = 7.70 ppm in 72 h) and fractions exhibited different level of mosquito larvicidal activity with subtraction of some fractions resulting in activity enhancement. The active fractions contained furanonaphthaquinones regio-isomers (LC50 = 5.48-5.70 ppm in 72 h) and the lantadene triterpenoid camaric acid (LC50 = 6.19 ppm in 72 h) as active principles while the lupane triterpenoid betulinic acid (LC50 < 10 ppm in 72 h) was obtained from the least active fraction. Crude extracts and some fractions had higher or comparable larvicidal activity to the pure compounds. These results demonstrate that L. viburnoides sp viburnoides var kisi extracts may serve as larvicides for managing various mosquito habitats even in their semi-purified form. The isolated compounds can be used as distinct markers in the active extracts or plant materials belonging to the genus Lantana
Recommended from our members
Immigration Legislation and Issues in the 111th Congress
[Excerpt] The Speaker of the House and the Senate Majority Leader have pledged to take up comprehensive immigration reform legislation at some point in the 111th Congress. Efforts to enact broad immigration reform in the 109th and 110th Congresses were unsuccessful. It is unclear what the components of any immigration reform proposals that the 111th Congress may consider will be. In the past, comprehensive bills have addressed border security, enforcement of immigration laws within the United States (interior enforcement), employment eligibility verification, temporary worker programs, permanent admissions and, most controversially, unauthorized aliens in the United States.
The 111th Congress has considered various immigration issues and has enacted a number of targeted immigration provisions. It has passed legislation (P.L. 111-8, P.L. 111-9, P.L. 111-68) to extend the life of several immigration programsâthe E-Verify electronic employment eligibility verification system, the Immigrant Investor Regional Center Program, the Conrad State J-1 Waiver Program, and the special immigrant visa for religious workersâall of which are currently authorized until October 31, 2009. With respect to these programs, the House-passed and Senate-passed versions of the Department of Homeland Security Appropriations Act, 2010 (H.R. 2892), include different provisions to further extend E-Verify. The Senate-passed bill also would extend the other three programs. Among the other subjects of legislation enacted by this Congress are refugees (P.L. 111-8) and border security (P.L. 111-5, P.L. 111-32).
This report discusses these and other immigration-related issues that have seen legislative action or are of significant congressional interest. Department of Homeland Security (DHS) appropriations are addressed in CRS Report R40642, Homeland Security Department: FY2010 Appropriations, and, for the most part, are not covered here. This report will be updated as legislative developments occur
A Reinsurance Approach in a Two-Dimensional Model with Dependent Risks
We consider an insurer having two classes of insurance risks dependent through
the number of claims of each risk in a given period of time. We assume that
the insurer chooses a reinsurance strategy related to the first class of risk by
means a proportional reinsurance contract; we also assume that the reinsurance strategy related to the second class of risk is of Excess of Loss reinsurance type. Within this paper, we study the possible optimal couples of proportional retention level and Excess of Loss retention limit
Phenotypic effect of mutations in evolving populations of RNA molecules
Abstract Background The secondary structure of folded RNA sequences is a good model to map phenotype onto genotype, as represented by the RNA sequence. Computational studies of the evolution of ensembles of RNA molecules towards target secondary structures yield valuable clues to the mechanisms behind adaptation of complex populations. The relationship between the space of sequences and structures, the organization of RNA ensembles at mutation-selection equilibrium, the time of adaptation as a function of the population parameters, the presence of collective effects in quasispecies, or the optimal mutation rates to promote adaptation all are issues that can be explored within this framework. Results We investigate the effect of microscopic mutations on the phenotype of RNA molecules during their in silico evolution and adaptation. We calculate the distribution of the effects of mutations on fitness, the relative fractions of beneficial and deleterious mutations and the corresponding selection coefficients for populations evolving under different mutation rates. Three different situations are explored: the mutation-selection equilibrium (optimized population) in three different fitness landscapes, the dynamics during adaptation towards a goal structure (adapting population), and the behavior under periodic population bottlenecks (perturbed population). Conclusions The ratio between the number of beneficial and deleterious mutations experienced by a population of RNA sequences increases with the value of the mutation rate Ό at which evolution proceeds. In contrast, the selective value of mutations remains almost constant, independent of Ό, indicating that adaptation occurs through an increase in the amount of beneficial mutations, with little variations in the average effect they have on fitness. Statistical analyses of the distribution of fitness effects reveal that small effects, either beneficial or deleterious, are well described by a Pareto distribution. These results are robust under changes in the fitness landscape, remarkably when, in addition to selecting a target secondary structure, specific subsequences or low-energy folds are required. A population perturbed by bottlenecks behaves similarly to an adapting population, struggling to return to the optimized state. Whether it can survive in the long run or whether it goes extinct depends critically on the length of the time interval between bottlenecks.Support from the Spanish MICINN through research project FIS2008-05273 is
gratefully acknowledged.Peer Reviewe
Entropy/IP: Uncovering Structure in IPv6 Addresses
In this paper, we introduce Entropy/IP: a system that discovers Internet
address structure based on analyses of a subset of IPv6 addresses known to be
active, i.e., training data, gleaned by readily available passive and active
means. The system is completely automated and employs a combination of
information-theoretic and machine learning techniques to probabilistically
model IPv6 addresses. We present results showing that our system is effective
in exposing structural characteristics of portions of the IPv6 Internet address
space populated by active client, service, and router addresses.
In addition to visualizing the address structure for exploration, the system
uses its models to generate candidate target addresses for scanning. For each
of 15 evaluated datasets, we train on 1K addresses and generate 1M candidates
for scanning. We achieve some success in 14 datasets, finding up to 40% of the
generated addresses to be active. In 11 of these datasets, we find active
network identifiers (e.g., /64 prefixes or `subnets') not seen in training.
Thus, we provide the first evidence that it is practical to discover subnets
and hosts by scanning probabilistically selected areas of the IPv6 address
space not known to contain active hosts a priori.Comment: Paper presented at the ACM IMC 2016 in Santa Monica, USA
(https://dl.acm.org/citation.cfm?id=2987445). Live Demo site available at
http://www.entropy-ip.com
Adversarial Deformation Regularization for Training Image Registration Neural Networks
We describe an adversarial learning approach to constrain convolutional
neural network training for image registration, replacing heuristic smoothness
measures of displacement fields often used in these tasks. Using
minimally-invasive prostate cancer intervention as an example application, we
demonstrate the feasibility of utilizing biomechanical simulations to
regularize a weakly-supervised anatomical-label-driven registration network for
aligning pre-procedural magnetic resonance (MR) and 3D intra-procedural
transrectal ultrasound (TRUS) images. A discriminator network is optimized to
distinguish the registration-predicted displacement fields from the motion data
simulated by finite element analysis. During training, the registration network
simultaneously aims to maximize similarity between anatomical labels that
drives image alignment and to minimize an adversarial generator loss that
measures divergence between the predicted- and simulated deformation. The
end-to-end trained network enables efficient and fully-automated registration
that only requires an MR and TRUS image pair as input, without anatomical
labels or simulated data during inference. 108 pairs of labelled MR and TRUS
images from 76 prostate cancer patients and 71,500 nonlinear finite-element
simulations from 143 different patients were used for this study. We show that,
with only gland segmentation as training labels, the proposed method can help
predict physically plausible deformation without any other smoothness penalty.
Based on cross-validation experiments using 834 pairs of independent validation
landmarks, the proposed adversarial-regularized registration achieved a target
registration error of 6.3 mm that is significantly lower than those from
several other regularization methods.Comment: Accepted to MICCAI 201
Greenhouse cover management: solar radiation effects on production and quality of a gerbera crop
Este trabalho propĂŽs avaliar a influĂȘncia das malhas de sombreamento (termorrefletora) instaladas externa e internamente em ambiente protegido coberto com polietileno de baixa densidade (PEBD), cultivado com gĂ©rbera, na radiação solar global (Qg) e nos parĂąmetros da planta: crescimento, desenvolvimento e qualidade da gĂ©rbera. O experimento foi conduzido em dois ciclos no ano de 2004, na ESALQ/USP, em Piracicaba, SP, em ambiente protegido, dividido em dois mĂłdulos de produção. Os ambientes foram diferenciados um do outro pela instalação da malha termorrefletora (50%): malha externa (ambiente 1 - A1) e malha interna (ambiente 2 - A2). Nesses ambientes, os resultados dos dois ciclos mostraram alteração na Qg; nos ambientes A1 e A2 as Qg foram respectivamente 33,6 e 21,7 (1Âș ciclo) e 27,2 e 17,9% (2Âș ciclo) em relação Ă observada externamente. Considerando-se os dois ciclos conclui-se que os resultados indicaram que nĂŁo houve diferenças na qualidade das plantas nos dois ambientes, mas, analisando-se separadamente os dois ciclos da cultura, o A1 (malha externa) foi o que mais favoreceu a qualidade das plantas de gĂ©rbera e somente as gĂ©rberas presentes no A1 (malha externa) atenderam Ă s exigĂȘncias mercadolĂłgicas, quanto aos nĂșmeros de botĂ”es florais.The objective of this study was to evaluate the influence of low density polyethylene (PEBD) as a greenhouse cover in association with thermal shading screen installed in two different positions (outside and inside), cultivated with gerbera, on solar radiation (Qg), as well as on the growth and quality of gerbera plants. The experiment was carried out during two crop cycles in 2004, at ESALQ/USP, in Piracicaba, State of SĂŁo Paulo, Brasil. A greenhouse was sub-divided into two parts and covered with PEBD differing from each other by the position of the thermal shading screen (50%), witch was installed inside (at 3 m height) and outside (covering the plastic cover). The environment with the thermal screen outside was named A1 and the other one with the thermal screen inside was named A2. The results from the two crop cycles showed that the microclimate was changed by the covers of the greenhouses. Qg inside for A1 and A2 were respectively 33.6 and 21.7 (first cycle), and 27.2 and 17.9% (second cycle) of the values measured outside. Considering the two crop cycles, the results showed that there were no differences in plant quality in both environments. However, A1 was the most favorable environment for plant quality when considering the two crop cycles, separately the results separately. Also, only gerberas from A1 showed themselves to have marketable characteristics
- âŠ