图像8邻域分形块编码

提出了8邻域分形块编码，其值域块的分形编码是基于对值域块最小均方差近似得来的。因而与基于搜索匹配的Jackquin分形块编码相比，它速度快，压缩比高。对512×512的“Lenna”图像实验结果表明:二级8邻域分形块编码每像素比特率可达到0．36bpp，峰值信噪比可达29．86dB，在PC486上，编码时间为64秒，解码时间为109秒。     

整环Z[c~(1/2)]中的素元及非唯一分解环

本文主要证明了整环 Z[c~(1/2)]当 c 为-1,2,-2,3时为唯一分解环。给出判断整环 Z(c~(1/2))中元素为素元的条件,并进而给出确定 Z[c~(1/2)]为非唯一分解环的特殊方法。     

Diversity of leaf-litter anurans in a fragmented landscape of the Atlantic Plateau of São Paulo State,southeastern Brazil

Brazil is a tropical country and has the greatest anuran species richness in the world: the Atlantic Forest has roughly half of these species. We contribute to the knowledge of the anurans of the Brazilian Atlantic Plateau, determining the composition of anuran fauna associated with leaf litter in six landscapes, patterns of spatial distribution and levels of similarity among these landscapes and other communities. The sampling by pitfall traps was conducted in São Paulo state, at a total of 68 sites distributed among continuous and fragmented landscapes. The anuran fauna of these sites is typical of dense ombrophilous forest, and the composition resembled those of other localities of the Atlantic Forest. A cluster analysis comparing the six landscapes resulted in three main groups (Caucaia + Reserva do Morro Grande; Tapiraí + Ribeirão Grande; Fazenda Paraíso + Parque Estadual Jurupará). In the cluster analysis comparing these faunas to those of other localities, we could not find an effect of geographic distance on the differences in composition among areas.     

New amphipods of hydrothermal vent environments on the Mid‐Atlantic Ridge,Azores Triple junction zone

This work is the third publication on the new amphipod species collected from the Azores Triple junction zone by the cruises ATOS, DIVA 2, MARVEL, PICO and SEAHMA 1. Seven new species and a new genus are described belonging to six families, Eusiridae, Leucothoidae, Oedicerotidae, Phoxocephalidae, Pleustidae, and Podoceridae. They were sampled in four sites, Menez Gwen, Lucky Strike, Saldanha and Rainbow.     

基于轨迹的指称语义方法

文章提出一种基于轨迹的指称语义框架,该框架结合了操作语义和代数语义的特征,避免使用专门的数学理论,将静态语义和动态语义结合在一起统一处理.文章引入了轨迹概念和模型语言,然后讨论该语言的各句法成分所对应的语义论域,并对过程和函数进行了一些描述。     

FIR 数字滤波器与频率采样

本文在频率采样理论的基础上提出了用矩降设计 FIR 数学滤波器的原理和方法。讨论了数字滤波器过渡带确定的规律和有关参数与滤波器质量指标之间的关系,推导出了闭合表达式,实现计算机分析的工程过程。     

Bloch线链传输特性的计算机模拟

本文用有限差分法求解磁泡薄膜畴壁运动非线性耦合微分方程组,讨论了二维含Bloch线链畴壁的边界条件和初始条件,用计算机模拟了VBL势阱对畴壁运动的影响及VBL传输特性.     

电磁场计算中的时域有限差分法

时域有限差分法是在离散变量空间和时间中求解不同边界条件下Maxwell方程组的一种数值方法。这种方法简单易懂,适应性强,所用计算机存储单元少,已在微波领域得到大量应用,目前又被应用于光场分布的研究。本文介绍了时域有限差分法的基本原理,推导了Maxwell方程组的FDTD数值表达式。     

Breeding in the gray-headed tody-flycatcher (Aves: Tyrannidae) with comments on geographical variation in reproductive traits within the genus Todirostrum

The gray-headed tody-flycatcher Todirostrum poliocephalum is a passerine endemic to the Atlantic Forest of Brazil. We describe the nest and nesting behaviour of this species and investigate geographical variation in breeding traits in the genus using data from the literature, museum collections, and citizen science projects. We located 21 nests of the gray-headed tody-flycatcher, 13 of which we monitored. Nest height above the ground averaged 3.3 ± 3.4 m (n = 21). Nests were built over a 16.8 ± 5.6-day period (n = 6) by both adults. Clutch sizes ranged from two to three eggs, with a mean of 2.9 ± 0.3 eggs (n = 10). Eggs measured 16.6 ± 0.5 × 12.0 ± 0.5 mm (n = 23) and weighed 1.1 ± 0.1 g (n = 19). Mean incubation period was 17 days (n = 3) and mean nestling period was 15.5 days (n = 2). Apparent reproductive success was 30.8%, with predation being the primary cause of nest failure (46.1%). Mayfield’s reproductive success was 25.9%, and daily survival rates for eggs and nestlings were 0.957 and 0.971, respectively. Clutch sizes increased with latitude, but temperature and precipitation seasonality had very low importance in explaining clutch size variation.     

Comparison of zooplankton community structure between impacted and non-impacted areas of Paranaguá Bay Estuarine Complex,south Brazil

We analysed the seasonal distribution of the zooplankton community in an anthropogenically impacted area (Paranaguá Bay) and a non-impacted area (Laranjeiras Bay) of the Paranaguá Bay Estuarine Complex. Large phytoplankton (> 50 μm) and zooplankton were collected every two months, between August 2003 and June 2004. The phytoplankton community was numerically dominated by diatoms (78%) and dinoflagellates (19%). Zooplankton abundance varied between 670 and 100,716 individuals m^–3, with a dominance of copepods, mainly the calanoids Acartia lilljeborgii, Acartia tonsa and Pseudodiaptomus acutus. A clear seasonal pattern was observed: copepods were significantly more abundant during the rainy than in the dry season. Significant differences in abundance between the two bays were detected only for cirripede larvae, which were more abundant in Paranaguá Bay. This lack of difference between the two areas was probably a consequence of the water circulation along the estuary, which may have diluted and dispersed the pollutants from Paranaguá Bay to other areas of the estuary.