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Hyperonic neutron stars: reconciliation between nuclear properties and NICER and LIGO/VIRGO results

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Communications in Theoretical Physics 2022年第1期74卷 57-63页

作者： luiz L lopes Centro Federal de Educagao Tecnologica de Minas Gerais Campus VIII CEP 37.022-560Varginha-MG-Brasil

Using an extended version of quantum hadrodynamics,I propose a new microscopic equation of state(EoS)that is able to correctly reproduce the main properties of symmetric nuclear matter at the saturation density,as well as produce massive neutron stars and satisfactory results for the radius and the tidal parameter.I show that this EoS can reproduce at least a 2.00 solar mass neutron star,even when hyperons are *** constraints about the radius of a 2.00 M_(⊙) and the minimum mass that enables a direct Urea effect are also checked.

关键词： neutron star nuclear matter tidal deformability DU process hyperons

The nest architecture of the ant, Pheidole oxyops Forel, 1908 （Hymenoptera： Formicidae）

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Insect Science 2007年第5期14卷 437-442页

作者： luiz C. FORTI ROBERTO S. CAMARGO RICARDO T. FUJIHARA JULIANE F. S. lopes Laboratorio de Insetos Sociais-Praga Departamento de Producao Vegetal - Setor Defesa Fitossanitaria FCA/UNESP Botucatu SP Comportamento e Ecologia Animal Instituto de Ciencias Biologicas Universidade Federal de Juiz de Fora Campus Universitario Martelos Juiz de Fora MG Brazil

Pheidole oxyops builds subterranean nests, with an external architecture that is distinctive and easily recognizable by its wide and specific entrance hole, measuring up to 12.2 cm in diameter, denoting a pitfall-trap. In order to study the nests＇ internal architecture, seven nests were excavated; four were identified with neutral talc, while the others were cast in cement and then excavated. Measurements were made in order to gain a better understand- ing of their structures, and a photographic documentation was obtained as well. The excavations revealed that the nests are perpendicular relative to the ground, beginning with a cylindrical channel with a mean length of 13.5 cm, containing irregular formations, and whose diameter becomes progressively narrower until the first chamber is formed. As the channel continues, dish-like chambers appear, interconnected by channels that become progressively narrower and longer, while the chambers are arranged at greater distances from each other as nest depth increases. Both channels and chambers are located on the vertical projection of the entrance hole. Nests may reach a depth of up to 5.09 m, with a number of chambers ranging between 4 and 14.

关键词： chambers nest architecture Pheidole pitfall-trap

Soil Attributes and Production of Eucalyptus in Monoculture and Silvopastoral Systems in the North of Minas Gerais, Brazil

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Journal of Agricultural Science and Technology(B) 2016年第6期6卷 361-370页

作者： Pedro Henrique lopes Santana Leidivan Almeida Frazao Leonardo David Tuffi Santos luiz Amaldo Femandes Regynaldo Arruda sampaio Centro de Ciencias Agrarias e Engenharias Universidadade Federal do Espirito Santo Alegre Espirito Santo 29500000 Brazil Instituto de Ciencias Agrarias Universidade Federal de Minas Gerais Montes Claros Minas Gerais 39404547 Brazil

The objective of this study was to evaluate the chemical and physical attributes of soil, and the productivity of Eucalyptus cultivated in monoculture and silvopastoral systems. The experiment started in 2009 and evaluated the following four systems： native vegetation system （Cerrado）, a degraded pasture, a Eucalyptus urograndis monoculture （E. urophylla x E. grandis） and a silvopastoral system （E. urograndis combined with Brachiaria brizantha cv. ＂Marandu＂）. The experimental design used was completely randomized. In each system, four soil samples were collected from the 0-20 cm depth layer, and the chemical and physical attributes of the soil were evaluated. The diameters of all Eucalyptus trees at 1.30 m above the ground as well as the total height were measured. Subsequently, the trees dimensions were measured and their individual volumes obtained by applying the Smalian formula. The correlation between the parameters for Eucalyptus production and soil attributes was established using the Pearson＇s correlation coefficient method. The planting of Eucalyptus in monoculture and silvopastoral systems contributed to the improvement of the soil＇s chemical and physical attributes, which indicates the potential of these systems for recovery of degraded pastures. The silvopastoral system yielded the highest average volume of wood per tree （0.2228 m^3）, with a productivity of 111.4 m^3/ha. The Eucalyptus monoculture yielded 0.1895 m^3 per tree and 315.71 m^3/ha due to the higher density of the crop. The growth and productivity of Eucalyptus showed highly correlation with the soil attributes, thus suggesting that well-managed crops are an indicator of the soil quality recovery.

关键词： Diameter at breast weight forest-livestock integration system forest production soil quality.

Influence of physical and chemical factors during foraging and culture of the symbiont fungus in Atta sexdens rubropilosa （Hymenoptera： Formicidae）

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Insect Science 2007年第4期14卷 295-300页

作者： SANDRA S. VERZA luiz C. FORTI JULIANE F. S. lopes ROBERTO S.CAMARGO CARLOS A. O. MATOS Departamento de Zoologia Instituto de Biociencias Laboratrio de Insetos Sociais-Praga Departamento de Produ~~o Vegetal-Def-esa Fitossanitaria Faculdade de Ciencias Agronomicas UNESP-Sao Paulo State University Fazenda Experimental LageadoBotucatu SP Comportamento e Biologia Animal Instituto de Ciencias Biologicas UFJF-Universidade Federal de Juiz de ForaCampus Universitario Martelos Juiz de Fora MG Campus Experimental de Itapeva UNESP Itapeva SP Brazil

The aim of this paper is to investigate the influence of physical and chemical factors on transport and use of substrate for Atta sexdens rubropilosa workers. Three types of rectangular fragments were used to study the physical influence factors： filter paper with paraffin, filter paper without paraffin and polyester film. To study the chemical factors, some fragments were impregnated with organic extract of orange albedo, others were soaked with soybean oil and for the remaining ones nothing was applied. The fonowing parameters were evaluated：（i） attractiveness of substrate for transport and number of loading workers per treatment; （ii） foraged material incorporation; （iii） rejection by numbers of fragments deposited in the garbage or beside the fungus garden. All the polyester film fragments carried out to the fungus garden were subsequently rejected. We verified that chemical factors of the substrate were more quickly detected by the workers, whereas physical factors were used as a criterion in the decision-making to reject or accept the substrate collected.

关键词： Atta sexdens rubropilosa attractiveness behavior leaf-cutting ants substraterejection substrate selection

Worker laying in leafcutter ant Acromyrmex subterraneus brunneus （Formicidae, Attini）

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Insect Science 2007年第2期14卷 157-163页

作者： ROBERTO S. CAMARGO luiz C. FORTI JULIANE F. S. lopes NEWTON C. NORONHA ANGELO L. T. OTTATI Departamento de Producāo Vegetal FCA/UNESP Botucatu SP Campus Universitário Paulo VI Sāo Luis MA Brazil. Comportamento e Biologia Animal Instituto de Ciencias Biológicas Universidade Federal de Juiz de Fora Campus Universitário Martelos Juiz de Fora MG Campus Universitário Paulo VI Sāo Luis MA Brazil. Departamento de Entomologia Fitopatologia e Zoologia Agricola Escola Superior de Agricultura 'Luiz de Queiroz' Universidade de Sao Paulo Piracicaba SP Campus Universitário Paulo VI Sāo Luis MA Brazil. Departamento de Fitotecnia e Fitossanidade Universidade Estadual do Maranhāo Centro de Ciencias Agrenias Campus Universitário Paulo VI Sāo Luis MA Brazil.

We studied the process of offspring production in queenless colonies of Acromyrmex subterraneus brunneus, and particularly evaluated the ovary development of workers as a function of their age. For this, subcolonies were set up and evaluated at different periods of isolation from the queen （2, 4 and 6 months）, besides individually labeled age groups. The subcolonies were assessed according to offspring production and ovaries containing oocytes or not. The evaluations showed worker oviposition and development of males originating from worker-laid eggs. At 2 months＇ absence of the queen, eggs and larvae were found, with eggs in a higher proportion than larvae. After 4 months, the proportion of eggs had reduced while larvae had increased, and a pupa was found in one subcolony. At 6 months, besides a higher share of larvae, one pupa and one adult male were found. Dissection of workers revealed ovaries containing oocytes during the periods of evaluation. Only a group of medium-sized and large workers, 23.3%, 20.9% and 37.5% of the population from each period assessed in queenless subcolonies respectively, presented developed oocytes in the ovary. The same was observed in colonies with a queen, with 17.6%, 19.6% and 7.8% of the group of dissected workers from each time period, respectively. With respect to worker age, we observed by dissection of the ovary, that the greatest percentage of individuals with ovarioles containing oocytes occurred at 45 days （6 weeks） up to 90 days （12 weeks）. These results probably are associated with the workers reproduction and the laying of trophic and reproductive eggs in colonies with and without a queen; these eggs have distinct functions in each situation.

关键词： leafcutter ant queenless ant colonies reproduction conflict worker laying,worker reproduction

A Virtual Synchronous Machine to Support Dynamic Frequency Control in a Mini-Grid That Operates in Frequency Droop Mode

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Energy and Power Engineering 2013年第3期5卷 259-265页

作者： Miguel Torres luiz A. C. lopes Department of Electrical and Computer Engineering Concordia University Montreal Canada

This paper addresses the problem of dynamic frequency control in a diesel-based mini-grid. It is shown that a virtual synchronous machine (VSM) can support dynamic frequency control by adding virtual inertia and damping to the system. However, it is found that the typical formulation of damping power does not work properly when the grid forming gen-set operates in droop mode because of the unknown stabilization value of the grid frequency. As a solution to this problem, an estimator for the stabilization frequency that works in conjunction with the damping function of the VSM is proposed. Theoretical and experimental results provide evidence of a satisfactory performance of the proposed VSM with estimator for different values of the gen-set droop factor. The estimated stabilization frequency converges in approximately 2 s and the maximum frequency deviation during the transient is reduced in 34%, on average.

关键词： Frequency Control Mini-Grid Inverter Virtual Synchronous Machine

Inverter-Based Diesel Generator Emulator for the Study of Frequency Variations in a Laboratory-Scale Autonomous Power System

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Energy and Power Engineering 2013年第3期5卷 274-283页

作者： Miguel Torres luiz A. C. lopes Department of Electrical and Computer Engineering Concordia University Montreal Canada

This paper presents the modeling, simulation and practical implementation of an inverter-based diesel generator emulator. The main purpose of this emulator is for the study of frequency variations in diesel-based autonomous power systems in a laboratory environment where the operation of a real diesel generator is not possible. The emulator basically consists in a voltage source inverter with a second order output filter which voltage references are given by the model of the diesel generator. The control of the emulator is based on the digital signal processor TMS320F2812, where the mathematical models of the diesel generator and the control of the inverter are computed in real-time. Parameters for the model were obtained from commercially available components. Experimental results for different values of speed droop showed that the emulator achieves a satisfactory performance in the transient and stationary response. For the stationary response, the measured frequency deviates from theoretical values with a mean absolute error of: 0.06 Hz for 0% droop, 0.037 Hz for 3% droop, and 0.087 Hz for 5% droop. For the transient response, the measured frequency nadir deviates from simulations in: 0.05 Hz for 0% droop, 0.02 Hz for 3% droop, and 0.1 Hz for 5% droop.

关键词： Diesel Generator Emulator Inverter Frequency Control Mini-Grid

Virtual Synchronous Generator: A Control Strategy to Improve Dynamic Frequency Control in Autonomous Power Systems

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Energy and Power Engineering 2013年第2期5卷 32-38页

作者： Miguel Torres luiz A. C. lopes Department of Electrical and Computer Engineering Concordia University Montreal Canada

Ideally, diesel hybrid autonomous power systems would operate with high penetration of renewable energy sources such as wind and photovoltaic to minimize fuel consumption. However, since these are inherently intermittent and fluctuating, the grid-forming diesel engine generator sets are usually required to operate with larger amounts of spinning reserve, often at low loading conditions what tends to increases operating and maintenance costs. Frequency stability is of great concern in “small” systems, such as mini-grids, where any individual generator in-feed represents a substantial portion of the total demand. There, the initial rate of change of frequency is typically larger and a lower value of frequency can be reached in a shorter time than in conventional systems with all generation supplied by rotating machines, possibly resulting in under-frequency load shedding and tripping of renewable energy generators. The first part of this paper, discusses some general concepts regarding frequency stability in a diesel hybrid mini-grid and how energy storage systems can be used to enhance system performance. Then, a particular technique based on a virtual synchronous generator is presented and its effectiveness is demonstrated with simulation results.

关键词： Frequency Control Mini-Grid Energy Storage Inverter

Heterogeneity in the Second Internal Transcribed Spacer (ITS2) of rDNA in the Genetically Distinct Metopolophium dirhodum Isofemale Lineages (Hemiptera: Aphididae)

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Advances in Entomology 2014年第4期2卷 194-201页

作者： Marcelo lopes-da-Silva luiz Gonzaga Esteves Vieira Plant Quarantine Laboratory Embrapa Genetic Resources and Biotechnology Brazilian Agriculture Research Corporation (Embrapa) Brasília DF Brazil University of Western São Paulo (Unoeste) Presidente Prudente Brazil

The aim of this study was to investigate the level of evolutionary divergence among five isofemale lineages of Metopolophium dirhodum Walker (Hemiptera: Aphididae) using sequences of the Internal Transcribed Spacer (ITS) of ribosomal DNA (rDNA). These isofemalelineages were derived from parthenogenetic females, previously genetically characterized by having strong association of RAPD (Random Amplified Polymorphic DNA) molecular markers and host plant preference. Out of 25 sequences, only 17 containing ITS2 (the second spacer) were used for analysis due to their quality. Within 250 nucleotide sites originated by multiple alignments, 10.4% were variable, with the predominance of indels over substitutions. The average of nucleotide diversity (π) within isofemale lineages was similar to the diversity found among all isofemale lineages. The topology inferred by the Neighbor-Joining method showed that no evolutionary divergence inferred by ITS2 sequences among isofemale lineages typified by RAPD could be associated with host preference. The ITS2 sequence differences found within lineages and their causes are discussed.

关键词： Aphid Clones Molecular Evolution DNA