1,723 research outputs found
Spatially Invariant Coding of Numerical Information in Functionally Defined Subregions of Human Parietal Cortex
Macaque electrophysiology has revealed neurons responsive to number in lateral (LIP) and ventral (VIP) intraparietal areas. Recently, fMRI pattern recognition revealed information discriminative of individual numbers in human parietal cortex but without precisely localizing the relevant sites or testing for subregions with different response profiles. Here, we defined the human functional equivalents of LIP (feLIP) and VIP (feVIP) using neurophysiologically motivated localizers. We applied multivariate pattern recognition to investigate whether both regions represent numerical information and whether number codes are position specific or invariant. In a delayed number comparison paradigm with laterally presented numerosities, parietal cortex discriminated between numerosities better than early visual cortex, and discrimination generalized across hemifields in parietal, but not early visual cortex. Activation patterns in the 2 parietal regions of interest did not differ in the coding of position-specific or position-independent number information, but in the expression of a numerical distance effect which was more pronounced in feLIP. Thus, the representation of number in parietal cortex is at least partially position invariant. Both feLIP and feVIP contain information about individual numerosities in humans, but feLIP hosts a coarser representation of numerosity than feVIP, compatible with either broader tuning or a summation cod
Occurrence of the Old World bug Megacopta cribraria (Fabricius) (Heteroptera: Plataspidae) in Georgia: a serious home invader and potential legume pest
Specimens of Megacopta cribraria (Fabricius) were collected in northern Georgia in late October 2009, where they were invading homes in large numbers. This is the first known occurrence of this species and the family Plataspidae in the New World. Megacopta cribraria was previously known from Asia and Australia. A key is provided to separate Plataspidae from other families of Pentatomoidea in America North of Mexico. A diagnosis and figures are provided to facilitate recognition of M. cribraria. Reported host plants and other aspects of the biology of this species are reviewed. Megacopta cribraria is considered a pest of numerous legumes in Asia, has the potential to provide biological control of kudzu, Pueraria montana var. lobata (Willd.) Ohwi, (Fabaceae) and likely will continue to be a household pest in the vicinity of kudzu fields as well as become a pest of North American legume crops
First record of \u3ci\u3eOrsilochides scurrilis\u3c/i\u3e (Stål) (Hemiptera: Heteroptera: Scutelleridae: Pachycorinae) in the United States, with notes on the biology and distribution of U.S. species of \u3ci\u3eOrsilochides\u3c/i\u3e Kirkaldy
Orsilochides scurrilis (Stål) (Hemiptera: Heteroptera: Scutelleridae) is reported from the United States for the first time based on a specimen collected in Santa Cruz County, Arizona. A key to separate the U.S. species of Orsilochides Kirkaldy is provided. In addition, host plant records and distribution of the other two species of Orsilochides that occur in the U.S., Orsilochides guttata (Herrich-Schäffer) and Orsilochides stictica (Dallas), are analyzed through a combination of digital photo records and museum specimens
Discovery of new TeV supernova remnant shells in the Galactic plane with H.E.S.S
Supernova remnants (SNRs) are prime candidates for efficient particle
acceleration up to the knee in the cosmic ray particle spectrum. In this work
we present a new method for a systematic search for new TeV-emitting SNR shells
in 2864 hours of H.E.S.S. phase I data used for the H.E.S.S. Galactic Plane
Survey. This new method, which correctly identifies the known shell
morphologies of the TeV SNRs covered by the survey, HESS J1731-347, RX
1713.7-3946, RCW 86, and Vela Junior, reveals also the existence of three new
SNR candidates. All three candidates were extensively studied regarding their
morphological, spectral, and multi-wavelength (MWL) properties. HESS J1534-571
was associated with the radio SNR candidate G323.7-1.0, and thus is classified
as an SNR. HESS J1912+101 and HESS J1614-518, on the other hand, do not have
radio or X-ray counterparts that would permit to identify them firmly as SNRs,
and therefore they remain SNR candidates, discovered first at TeV energies as
such. Further MWL follow up observations are needed to confirm that these newly
discovered SNR candidates are indeed SNRs
Understanding Risk Perception and Xenophobic Attitudes during the Coronavirus Disease 2019 (COVID-19) Pandemic in the United States
Introduction: There have been over 87 million cases of Coronavirus Disease 2019 (COVID-19) in the United States (US).
Objective: The objective of this study was to develop a novel questionnaire to assess risk perception of COVID-19 and xenophobic attitudes among adults in the US at the beginning of the pandemic.
Methods: An anonymous self-report questionnaire was developed for this study in February 2020, and was distributed using convenience sampling from March 10 to March 25, 2020. The questionnaire assessed knowledge and risk perceptions of COVID-19, as well as attitudes toward individuals of various races and ethnicities.
Results: 662 US adults completed the questionnaire. On a scale from 1 (low) to 5 (high), the mean risk perception was 3.44. Those with knowledge of COVID-19 and higher education levels reported higher risk perception and higher feelings of warmth towards Asian people. Forty percent of the sample had recently witnessed or experienced anti-Asian attitudes at the time of the survey. The majority of participants reported having heard about COVID-19 from news media, social media, and family or friends.
Conclusions: Our sample had a moderate level of risk perception, potentially due to the time period of data collection (i.e., early in the pandemic course). The results suggest that knowledge about COVID-19 informed perceived risk and affected willingness to engage in healthy protective behaviors. Our study provides historic context of how people perceived the virus at the beginning of the pandemic, and gives insight into the aftermaths regarding quarantine and attitudes towards Asian Americans
Definição da folha a ser amostrada para monitoramento de Mosca Branca (Bemisia tuberculata) na cultura da mandioca (Manihot esculenta Crantz).
A mandioca (Manihot esculenta Crantz) é uma cultura com crescente importância no mundo tropical, sendo a terceira fonte de calorias, atrás apenas do arroz e do milho, sendo utilizada na alimentação de cerca de 600 milhões de pessoas. No Brasil, aproximadamente 90% da produção da mandioca é obtida em propriedades de base familiar, sendo o país o terceiro produtor mundial, depois da Nigéria e da Tailândia, com uma produção de 26,52 milhões de toneladas de raízes, obtidas em uma área de cerca de 1,89 milhão de ha, o que corresponde a 12,37% da produção mundial e 10,20% da área, respectivamente (FAOSTAT, 2009). Essa é provavelmente a espécie vegetal mais disseminada pelo país, numa demonstração da profunda identificação entre essa cultura e o povo brasileiro. A cultura se caracteriza pela baixa necessidade de uso de insumos e agroquímicos, tem alta tolerância a períodos de seca, além de poder permanecer no solo até seu consumo, desempenhando papel importante na alimentação da população brasileira (CAMARGO, 2009). No entanto, por apresentar um longo ciclo vegetativo, está sujeita a uma grande diversidade de artrópodes que dela se alimentam (BELLOTTI et al., 1999). Dentro do complexo de insetos praga que atacam a cultura atualmente no Brasil, relata-se o crescimento da importância das espécies de mosca branca. Os gêneros mais importantes descritos atacando a cultura da mandioca no Brasil são Aleurothrixus aepim, Bemisia tuberculata, Trialeurodes variabilis e Bemisia tabaci biótipo B (OLIVEIRA & LIMA, 2006). No Centro-Sul do Brasil a espécie predominante é B. tuberculata, enquanto que no Nordeste destaca-se a espécie A. aepim (OLIVEIRA & LIMA, 2006). As moscas brancas causam danos diretos e indiretos, resultantes da sucção da seiva e transmissão de viroses, respectivamente (OLIVEIRA & LIMA, 2006). Para a supressão das populações desses insetos, apesar da existência de diversos inimigos naturais (BELLOTTI et al., 1999), tem-se predominado a utilização de inseticidas químicos, ainda que sem registros para essa cultura (AGROFIT, 2013) e ineficientes no controle do complexo de moscas brancas (MOREIRA et al., 2006). A utilização de variedades resistentes é outra estratégia de controle dessa praga, pois a mandioca é uma das poucas culturas onde se têm identificado níveis de resistência ao complexo de moscas brancas (CARABALI et al, 2010; OMONGO et al, 2012). Esta estratégia apresenta baixo custo e longa manutenção da população da praga abaixo do nível de dano econômico, além de reduzir perdas no rendimento, sendo uma importante ferramenta para ser incluída em um programa de manejo integrado de pragas (BELLOTTI et al., 1999). Para o estabelecimento de um eficiente programa de manejo integrado de pragas, além de utilizar várias estratégias de controle, é de suma importância um bom monitoramento da população da praga, visando à adoção de medidas de controle no momento ideal. Para a cultura da mandioca não se tem estabelecido um método de monitoramento preciso, eficiente e de baixo custo, principalmente para mosca branca. Observa-se que na cultura da mandioca os adultos de moscas brancas são encontrados principalmente nos ponteiros das plantas, onde se observa que o número de adultos presentes nas três primeiras folhas abertas, onde estes se alimentam e depositam seus ovos, é maior. Já as ninfas e 'pupas' são encontradas no terço apical e médio. Visando estabelecer um método de amostragem, que efetivamente seja representativo da população de mosca branca na cultura da mandioca, e considerando as características de localização dos adultos, se realizou este trabalho, cujo objetivo foi definir qual folha de mandioca deve ser amostrada durante o monitoramento de mosca branca em cultivos comerciais de mandioca, que expressem o nível populacional desta praga no cultivo
The ideal gas as an urn model: derivation of the entropy formula
The approach of an ideal gas to equilibrium is simulated through a
generalization of the Ehrenfest ball-and-box model. In the present model, the
interior of each box is discretized, {\it i.e.}, balls/particles live in cells
whose occupation can be either multiple or single. Moreover, particles
occasionally undergo random, but elastic, collisions between each other and
against the container walls. I show, both analitically and numerically, that
the number and energy of particles in a given box eventually evolve to an
equilibrium distribution which, depending on cell occupations, is binomial
or hypergeometric in the particle number and beta-like in the energy.
Furthermore, the long-run probability density of particle velocities is
Maxwellian, whereas the Boltzmann entropy exactly reproduces the
ideal-gas entropy. Besides its own interest, this exercise is also relevant for
pedagogical purposes since it provides, although in a simple case, an explicit
probabilistic foundation for the ergodic hypothesis and for the maximum-entropy
principle of thermodynamics. For this reason, its discussion can profitably be
included in a graduate course on statistical mechanics.Comment: 17 pages, 3 figure
Part Variation Modeling to Avoid Scrap Parts in Multi-stage Production Systems
Manufacturing systems for today's products are complex systems requiring a variety of different processes in order to be able to manufacture all necessary part features. This also applies to the production of rotating components, which have experienced increasing demand at the latest due to the growth in mobility. As in almost every manufacturing process, quality-reducing defects can occur due to deviations for example tool wear, which cannot always be avoided. Those, that have accumulated from previous process steps can cause the occurrence of superimposed defects. This leads to complex relationships between quality defects in the end product and the numerous parameters of the manufacturing processes. To remain competitive, production must be optimized in order to identify defects as early as possible, as well as their dependencies and variation patterns. The paper presents an approach to identify and model part variations within multi-stage production systems. Subsequently, based on a detected deviation, a downstream compensation strategy can be proposed at an early stage of the manufacturing process, which uses the capability of the overall system to fundamentally eliminate rejects
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