486 research outputs found
USORT: AN EFFICIENT HYBRID OF DISTRIBUTIVE PARTITIONING SORTING
A new hybrid of Distributive Partitioning Sorting is described and tested against Quicksort on uniformly distributed items. Pointer sort versions of both algorithms are also tested
ON THE COMPUTATION OF MINIMUM ENCASING RECTANGLES AND SET DIAMETERS
Two new algorithms are described for the following
problems: given a set of N points in the plane determine (i) the rectangle of minimum area which will completely cover (or encase) the set and (ii) the two points that are farthest apart (diameter of the set). Both algorithms have O(NlogN) time complexity and are based upon a similar strategy
Ground-state properties of rutile: electron-correlation effects
Electron-correlation effects on cohesive energy, lattice constant and bulk
compressibility of rutile are calculated using an ab-initio scheme. A
competition between the two groups of partially covalent Ti-O bonds is the
reason that the correlation energy does not change linearly with deviations
from the equilibrium geometry, but is dominated by quadratic terms instead. As
a consequence, the Hartree-Fock lattice constants are close to the experimental
ones, while the compressibility is strongly renormalized by electronic
correlations.Comment: 1 figure to appear in Phys. Rev.
Особенности энергетического расчета оптико-электронных систем обнаружения подводных объектов при наличии «солнечной дорожки»
Розглядається розрахунок освітленості в товщі води, що є складовою енергетичного розрахунку оптико-електронної системи (ОЕС) виявлення підводних об’єктів (ПО), при наявності «сонячної доріжки». Врахування явища «сонячної доріжки» в енергетичному розрахунку може суттєво вплинути на технічні характеристики такої ОЕС. За базовий використовується розрахунок, який був виконаний для випадку розміщення ОЕС під водою. Аналізується можливість використання такого розрахунку для випадку розміщення ОЕС на борту літального апарата і спостереження ПО крізь морську поверхню. Проведено чисельне моделювання освітленості у товщі води, що враховує компоненту, обумовлену власне «сонячною доріжкою», і компоненту, обумовлену розсіяним в передню півсферу випромінюванням. Показано, що отримані результати розрахунку компоненти освітленості, обумовленої «сонячною доріжкою», суттєво занижені порівняно з результатами розрахунку освітленості в товщі води, проведеного без урахування явища «сонячної доріжки». Визначено, що головна причина такої невідповідності полягає у недосконалості врахування впливу хвилювання морської поверхні на проходження оптичного випромінювання крізь границю середовищ «повітря-вода». Подальший напрямок досліджень пов’язаний з удосконаленням врахування цього впливу.Calculation of illumination in the water column that is the part of energy calculation of electro-optical system (EOS) of undersea object (UO) detection in the presence of “solar path” is considered. Taking into account of “solar path” phenomena in energy calculation may to considerably influence on technical characteristics for such EOS. Calculation for case of undersea EOS placement is taking as basic. Possibility to use of this calculation for case of aircraft side EOS placement and observation of UO through the sea surface is analyzed. Computational modeling of illumination in the water column with taking into account of “solar path” component and component of forward diffuse radiation is carried. It is display that the received results of calculation of “solar path” illumination component are considerably understated in comparison with results of calculation of water column illumination without “solar path” phenomena. It is identify that the main cause of this disagreement is the imperfection of accounting of rough sea phenomena influence on optical transmission through the surface “air-water”. Further direction of study is associated with improvement of accounting of this influence.Рассматривается расчет освещенности в толще воды, который является составляющей энергетического расчета оптико-электронной системы (ОЭС) обнаружения подводных объектов (ПО), при наличии «солнечной дорожки». Учет явления «солнечной дорожки» в энергетическом расчете может существенно повлиять на технические характеристики такой ОЭС. За базовый используется расчет, выполненный для случая размещения ОЭС под водой. Анализируется возможность использования такого расчета для случая размещения ОЭС на борту летательного аппарата и наблюдения ПО сквозь морскую поверхность. Проведено численное моделирование освещенности в толще воды, которое учитывает компоненту, обусловленную собственно «солнечной дорожкой», и компоненту, обусловленную рассеянным в переднюю полусферу излучением. Показано, что полученные результаты расчета компоненты освещенности, обусловленной «солнечной дорожкой», существенно занижены по сравнению с результатами расчета освещенности в толще воды, проведенного без учета явления «солнечной дорожки». Определено, что главная причина такого несоответствия состоит в несовершенстве учета влияния волнения морской поверхности на прохождение оптического излучения сквозь границу сред «воздух-вода». Дальнейшее направление исследований связано с усовершенствованием учета этого влияния
Trap-nesting biology of an ectoparasitoid spider wasp, Auplopus subaurarius (Hymenoptera: Pompilidae): the importance of wooded environments for niche generalist species
Abstract The insect group is one of the most diverse on the planet and due to habitat degradation, many of these species are becoming extinct, leaving a lack of information on the basic biology of each one. In this study, previously unseen information about nesting biology is revealed in Auplopus subaurarius trap nests. This is a solitary ectoparasitoid spider wasp that nests in preexisting cavities. We used a trap-nesting methodology to sample A. subaurarius in two different sampling periods (2017/2018 and 2020/2021) in three types of environment (forest, grassland and Eucalyptus plantation). In our study, the A. subaurarius nest building was more frequent during the hottest months of the year (November to March), with its highest abundance found within natural forest areas and in Eucalyptus plantation than in grassland areas. In addition, the species had two development times: a short one (three months) and a delayed one (up to one year). Moreover, females were larger than males (weight and size) and the species’ sex ratio had a tendency toward female production. Auplopus subaurarius presented seven natural enemy species: Ceyxia longispina, Caenochrysis crotonis, Photochryptus sp.1, Photochryptus sp.2, Messatoporus sp., Ephuta icema and Sphaeropthalma sp. We emphasize the importance of wooded environments to maintain the A. subaurarius populations and their associated interactors, both spiders and natural enemies, as these environments can provide better life conditions than grassland areas. Furthermore, other solitary wasps that may have the same lifestyle of A. subaurarius can also be improved by natural forest conservation and by good silviculture plantation planning, which should consider ecological aspects of Atlantic Forest landscapes
Chlorophyll a fluorescence parameters in the evaluation of oat DH lines yield components
Chlorophyll a fluorescence can provide insight into the ability of plants to tolerate environmental conditions that can damage photosynthetic apparatus and decrease yield. The aim of the study was to determine the relationship between chlorophyll a fluorescence parameters and yield components of oat DH lines. All DH lines significantly differed in chlorophyll a fluorescence parameters and yield components. The overall performance index of PSII photochemistry (PI), showed the highest variation between DH lines, whereas the lowest had the ratio of variable to maximum fluorescence (Fv/Fm). The highest differences were observed in the number of grains per plant (21.3 to 600). Thousand-grain weight varied from 17.82 g to 41.01 g and the biomass from 8.01 g to 29.31 g. The highest negative correlations were found between Fv/Fm, Area (pool size of electron acceptors from PSII), PI and grain number per plant and biomass. Positive correlations were observed between light energy absorption (ABS/CS), grain number per plant and biomass, as well as the amount of excitation energy trapped in PSII reaction centers (TRo/CS) and biomass. Principal component analysis of chlorophyll a fluorescence parameters, together with yield components, discriminated two oat DH lines groups according to their photosynthetic efficiency and yield
Electron affinities of the first- and second- row atoms: benchmark ab initio and density functional calculations
A benchmark ab initio and density functional (DFT) study has been carried out
on the electron affinities of the first- and second-row atoms. The ab initio
study involves basis sets of and quality, extrapolations to
the 1-particle basis set limit, and a combination of the CCSD(T), CCSDT, and
full CI electron correlation methods. Scalar relativistic and spin-orbit
coupling effects were taken into account. On average, the best ab initio
results agree to better than 0.001 eV with the most recent experimental
results. Correcting for imperfections in the CCSD(T) method improves the mean
absolute error by an order of magnitude, while for accurate results on the
second-row atoms inclusion of relativistic corrections is essential. The latter
are significantly overestimated at the SCF level; for accurate spin-orbit
splitting constants of second-row atoms inclusion of (2s,2p) correlation is
essential. In the DFT calculations it is found that results for the 1st-row
atoms are very sensitive to the exchange functional, while those for second-row
atoms are rather more sensitive to the correlation functional. While the LYP
correlation functional works best for first-row atoms, its PW91 counterpart
appears to be preferable for second-row atoms. Among ``pure DFT'' (nonhybrid)
functionals, G96PW91 (Gill 1996 exchange combined with Perdew-Wang 1991
correlation) puts in the best overall performance. The best results overall are
obtained with the 1-parameter hybrid modified Perdew-Wang (mPW1) exchange
functionals of Adamo and Barone [J. Chem. Phys. {\bf 108}, 664 (1998)], with
mPW1LYP yielding the best results for first-row, and mPW1PW91 for second-row
atoms. Indications exist that a hybrid of the type mPW1LYP +
mPW1PW91 yields better results than either of the constituent functionals.Comment: Phys. Rev. A, in press (revised version, review of issues concerning
DFT and electron affinities added
Strangeness nuclear physics: a critical review on selected topics
Selected topics in strangeness nuclear physics are critically reviewed. This
includes production, structure and weak decay of --Hypernuclei, the
nuclear interaction and the possible existence of bound
states in nuclei. Perspectives for future studies on these issues are also
outlined.Comment: 63 pages, 51 figures, accepted for publication on European Physical
Journal
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