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Minimum Size (minimum + size)
Terms modified by Minimum Size Selected AbstractsSize at the onset of sexual maturity in the anomuran crab, Aegla uruguayana (Aeglidae)ACTA ZOOLOGICA, Issue 4 2006Verónica E. Viau Abstract The size at maturity was studied in the crab Aegla uruguayana from the Areco River (31°14, S, 59°28, W), Argentina. Size at sexual maturity was determined according to three criteria: morphometric (change in the relative growth of reproductive characters), histological (first maturation of gonads) and functional (capability to mate and carry eggs). Regarding females, morphometric maturity occurred at a carapace length (CL) of 11.50 mm, considering abdomen width as a reproductive character. Gonad maturity of females could be observed at a minimum size ranging from 15 to 17 mm CL. The smallest ovigerous female observed in the field was 15.60 mm CL, although a relevant population incidence of ovigerous females (86.6%) has just been observed at values higher than 17 mm CL. As for males, the relative growth of the left chela length changed at a value of 15.40 mm CL, while morphological changes in sexual tube occurred between CL of 14 and 16 mm. Testicular maturation occurred at a CL ranging from 17 to 19 mm. The smallest size of males having spermatozoids in their vasa deferentia was 18.70 mm CL. The results obtained indicated that, in both sexes, functional maturity occurred after morphometric maturity and at a size similar to that of gonad maturity. Comparing sexes, females acquired sexual maturity (morphometric, gonad and functional maturity) at sizes statistically smaller than those of males. [source] The Process and Causes of Fledging in a Cavity-Nesting Passerine Bird, the House Wren (Troglodytes aedon)ETHOLOGY, Issue 9 2004L. Scott Johnson Little is known about the process or causes of fledging or nest-leaving in passerine birds because researchers can rarely predict when fledging will occur in a given nest. We used continuous videotaping of nests to both document the process of fledging in the house wren, Troglodytes aedon, a small, cavity-nesting songbird, and test hypotheses as to what might cause fledging to begin. Fledging began any time from 14 to 19 d after hatching commenced. Slower-developing broods fledged later than faster-developing broods. Fledging typically began within 5 h of sunrise and over 80% of all nestlings fledged before noon. All nestlings fledged on the same day at 65% of nests and over two consecutive days in most other nests. We found no evidence that fledging was triggered by changes in parental behaviour. Parental rate of food delivery to nestlings did not decline during a 3-h period leading up to the first fledging, nor was the rate of feeding just prior to the first fledging lower than the rate at the same time the day before. Moreover, parents did not slow the rate of food delivery to nests after part of the brood had fledged. Hatching is asynchronous in our study population which creates a marked age/size hierarchy within broods. At most nests, the first nestling to fledge was the most well-developed nestling in the brood or nearly so (as measured by feather length). This suggests that fledging typically begins when the most well-developed nestlings in the brood reach some threshold size. However, at about one-fifth of nests, the first nestling to fledge was only moderate in size. At these nests, severe competition for food may have caused smaller, less competitive nestlings to fledge first to increase their access to food. We found no strong support for the suggestion that the oldest nestlings delay fledging until their least-developed nestmate reaches some minimum size, although further experimental work on this question is warranted. [source] A dwarf species of the Phalacrocoracoidea (cormorants and anhingas) from the early Miocene of GermanyIBIS, Issue 2 2009GERALD MAYR A tarsometatarsus of a diminutive representative of the Phalacrocoracoidea, the clade including the Phalacrocoracidae (cormorants) and Anhingidae (anhingas), is described from the early Miocene of Germany. The fossil is assigned to a new species Limicorallus (?) carbunculus, and closely resembles the tarsometatarsus of extant Phalacrocoracidae in overall morphology. Limicorallus (?) carbunculus is the smallest representative of the Phalacrocoracoidea, reaching only two-thirds the size of the extant Pygmy Cormorant Phalacrocorax pygmeus. By significantly lowering the minimum size of the Phalacrocoracoidea, this new species adds to our knowledge of the early diversity of this clade. [source] Factors Affecting Macroinvertebrate Richness and Diversity in Portuguese Streams: a Two-Scale AnalysisINTERNATIONAL REVIEW OF HYDROBIOLOGY, Issue 2 2004Manuel A. S. Graça Abstract We analysed the spatial patterns in macroinvertebrate taxon richness and abundance at two scales: sampling unit and basin. We sampled 12 stream sites in three zones of Portugal, differing in climate geomorphology and water chemistry. At a sampling unit scale, substratum organic matter content, depth and the dominant size of substratum particles were correlated with numbers of taxa and individuals. We propose that the number of taxa at a small scale depends on the number of individuals, which in turn is the result of organic matter accumulation, hydrologic and substratum characteristics. The environmental parameters better explaining the large-scale biological data were temperature, minimum size of substratum particles and pH. Regardless of the relative importance of variable types and mechanisms regulating stream invertebrates along the climatic gradient, rivers from the North and Centre appeared to be richer in taxa than the typically Mediterranean streams in the South. [source] Reproductive biology of the silver pomfret, Pampus argenteus (Euphrasen), in Kuwait watersJOURNAL OF APPLIED ICHTHYOLOGY, Issue 6 2000S. Dadzie Summary The reproductive activities of the silver pomfret, Pampus argenteus (Euphrasen), in Kuwait waters were investigated from March 1996 to February 1998. Observations on the seasonal distribution of maturity stages and variations in seasonal fluctuations in the gonadosomatic index (GSI) confirmed recent findings that the spawning period begins in May. The species has a prolonged spawning period in the females extending from May to August, whereas the males mature in April and ripe specimens were encountered in monthly samples until September. The recruitment pattern confirmed the one breeding season. There are two spawning peaks, the first in May and the second in August. Variations in GSI relative to fish length indicated that females and males are most fecund at about 24.5,26.4 cm and 20.5,22.4 cm length classes, respectively. The males mature earlier than females, at a minimum size of 12.5,14.4 cm, while the females mature at 20.5,22.4 cm. The oocyte diameter-frequency distribution suggests a serial rhythm of spawning. Fecundity ranged from 28 965 to 455 661 and correlated positively with: (a) standard length (P < 0.006); (b) ovary weight (P < 0.001); and (c) body weight (P < 0.001), and negatively with egg size (P < 0.003). [source] Tomography-Based Multiscale Analyses of the 3D Geometrical Morphology of Reticulated Porous CeramicsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 8 2008Jörg Petrasch X-ray microtomography with a digital resolution of 30 ,m and synchrotron submicrometer tomography with a digital resolution of 350/700 nm are performed on catalyst-coated reticulate porous ceramic foa, 22[2] 121,45ms. Porosity, specific surface, pore-size distribution, two-point correlation function, and minimum size of a representative elementary volume are computed by image processing of the tomographic reconstructions on the mm-scale- and ,m-scale-sized pores. Numerically determined porosities are experimentally validated by weighing, helium pycnometry, and mercury intrusion porosimetry. [source] Compact UWB printed antennas for low frequency applications matched to different transmission linesMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 6 2007S. Tourette Abstract A rectangular monopole antenna fed by microstrip, stripline, or coplanar waveguide is studied and enhanced to offer the widest bandwidth with minimum size. A particular attention is focused on ground plans design and coupling between patch and transmission line in order to maintain UWB characteristics and low profile whatever transmission line is used. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1282,1287, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22462 [source] Novel antennas for ultra-wideband communicationsMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 3 2004N. Fortino Abstract Two novel antennas for UWB communications, both inspired from bowtie and triangular patch structures, are presented and tested. This paper proposes their study and optimization in order to cover the new WPAN standard and facilitate their integration on communication devices. This work has then been centered around three specific goals: wide bandwidth, minimum size, and low cost. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 41: 166,169, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20082 [source] A simple and linear time randomized algorithm for computing sparse spanners in weighted graphs,RANDOM STRUCTURES AND ALGORITHMS, Issue 4 2007Surender Baswana Abstract Let G = (V,E) be an undirected weighted graph on |V | = n vertices and |E| = m edges. A t -spanner of the graph G, for any t , 1, is a subgraph (V,ES), ES , E, such that the distance between any pair of vertices in the subgraph is at most t times the distance between them in the graph G. Computing a t -spanner of minimum size (number of edges) has been a widely studied and well-motivated problem in computer science. In this paper we present the first linear time randomized algorithm that computes a t -spanner of a given weighted graph. Moreover, the size of the t -spanner computed essentially matches the worst case lower bound implied by a 43-year old girth lower bound conjecture made independently by Erd,s, Bollobás, and Bondy & Simonovits. Our algorithm uses a novel clustering approach that avoids any distance computation altogether. This feature is somewhat surprising since all the previously existing algorithms employ computation of some sort of local or global distance information, which involves growing either breadth first search trees up to ,(t)-levels or full shortest path trees on a large fraction of vertices. The truly local approach of our algorithm also leads to equally simple and efficient algorithms for computing spanners in other important computational environments like distributed, parallel, and external memory. © 2006 Wiley Periodicals, Inc. Random Struct. Alg., 2007 [source] Evaluating the physiological and physical consequences of capture on post-release survivorship in large pelagic fishesFISHERIES MANAGEMENT & ECOLOGY, Issue 2 2007G. B. SKOMAL Abstract, Sharks, tunas and billfishes are fished extensively throughout the world. Domestic and international management measures (quotas, minimum sizes, bag limits) mandate release of a large, yet poorly quantified, number of these fishes annually. Post-release survivorship is difficult to evaluate, because standard methods are not applicable to large oceanic fishes. This paper presents information on the current approaches to characterising capture stress and survivorship in sharks, tunas and marlins. To assess mortality associated with capture stress, researchers must examine the cumulative impacts of physical trauma and physiological stress. Physical trauma, manifested as external and internal tissue and organ damage, is caused by fishing gear and handling. Gross examination and histopathological sampling have been used to assess physical trauma and to infer post-release survivorship. Exhaustive anaerobic muscular activity and time out of water cause physiological stress, which has been quantified in these fishes through the analyses of blood chemistry. Conventional, acoustic and archival tagging have been used to assess post-release survivorship in these species. Future studies relating capture stress and post-release survivorship could yield information that helps fishermen increase survivorship when practicing catch and release. [source] | |||||||||||||