Wide Branch Research Articles

Morphologies of long chain branched isotactic polypropylene crystallized from melt

The crystallization behavior and resulting crystalline morphologies of long chain branched isotactic polypropylene (LCBPP) under different conditions were studied by means of differential scanning calorimetry and transmission electron microscopy combined with electron diffraction. The results indicate that the crystallization of LCBPP during fast cooling process, or at lower crystallization temperature, leads to the formation of mainly edge-on lamellar structures. The LCBPP exhibits also the wide angle lamellar branching frequently observed for linear isotactic polypropylene. Crystallizing LCBPP in temperature range of 110∼140 °C results in the formation of both edge-on and flat-on crystals, which coexist side by side with the content of flat-on crystals increases with increasing crystallization temperature. At high crystallization temperature, e.g. 145 °C, flat-on crystals with chain axis aligned perpendicular to the film plane are the only observed morphology. Moreover, the crystals of LCBPP grow slower than its linear counterpart and the crystal growth rates of both linear and long branched PPs are temperature dependent.

The Development of Neuronal Morphology in Insects

Neurons are highly polarized cells with some regions specified for information input--typically the dendrites--and others specialized for information output--the axons. By extending to a specific location and branching in a specific manner, the processes of neurons determine at a fundamental level how the nervous system is wired to produce behavior. Recent studies suggest that relatively small changes in neuronal morphology could conceivably contribute to striking behavioral distinctions between invertebrate species. We review recent data that begin to shed light on how neurons extend dendrites to their targets and acquire their particular branching morphologies, drawing primarily on data from genetic model organisms. We speculate about how and why the actions of these genes might facilitate the diversification of dendritic morphology.

A neural network to improve dim-light vision? Dendritic fields of first-order interneurons in the nocturnal bee Megalopta genalis

Using the combined Golgi-electron microscopy technique, we have determined the three-dimensional dendritic fields of the short visual fibres (svf 1-3) and first-order interneurons or L-fibres (L1-4) within the first optic ganglion (lamina) of the nocturnal bee Megalopta genalis. Serial cross sections have revealed that the svf type 2 branches into one adjacent neural unit (cartridge) in layer A, the most distal of the three lamina layers A, B and C. All L-fibres, except L1-a, exhibit wide lateral branching into several neighbouring cartridges. L1-b shows a dendritic field of seven cartridges in layers A and C, dendrites of L2 target 13 cartridges in layer A, L3 branches over a total of 12 cartridges in layer A and three in layer C and L4 has the largest dendritic field size of 18 cartridges in layer C. The number of cartridges reached by the respective L-fibres is distinctly greater in the nocturnal bee than in the worker honeybee and is larger than could be estimated from our previous Golgi-light microscopy study. The extreme dorso-ventrally oriented dendritic field of L4 in M. genalis may, in addition to its potential role in spatial summation, be involved in edge detection. Thus, we have shown that the amount of lateral spreading present in the lamina provides the anatomical basis for the required spatial summation. Theoretical and future physiological work should further elucidate the roles that this lateral spreading plays to improve dim-light vision in nocturnal insects.

Propagation of Long Water Waves through Branching Channels

This paper investigates the fundamental behavior of long water waves propagating through branching channels of uniform depth and width. Numerical simulations based on the Boussinesq long wave model were carried out to investigate the effects of channel width b, effective wavelength λe, wave amplitude α, and angle θ between channel branches on wave transmission and reflection. Our results showed that the transmission and reflection of long waves through branching channels are dominantly governed by a single dimensionless parameter b∕λe, whereas other parameters such as the angle between channel branches are less important. Detailed quantitative results for predicting long wave transmission and reflection in different branching channels based on the similarity parameter b∕λe were determined. From these results, we have discovered some very interesting and distinct long wave behaviors in narrow and wide branching channels. To verify the numerical results, experiments were conducted in a right-angled branching channel, and the experimental results showed good agreement with the numerical predictions.

Deep ACS Imaging of the Halo of NGC 5128: Reaching the Horizontal Branch

Using the Hubble Space Telescope (HST) Wide Field Camera (WFC) of the Advanced Camera for Surveys (ACS), we have obtained deep (V, I) photometry of an outer halo field in NGC 5128, to a limiting magnitude of I 29. Our photometry directly reveals the core helium burning stellar population (the red clump or horizontal branch) in a giant E/S0 galaxy for the first time. The color-magnitude diagram displays a very wide red giant branch (RGB), an asymptotic giant branch (AGB) bump, and the red clump; no noticeable population of blue horizontal branch stars is present, confirming previous suggestions that old, very metal-poor population is not ubiquitous in the halo of this galaxy. From the upper RGB we derive the metallicity distribution, which we find to be very broad and moderately metal-rich, with average [M/H] = -0.64 and dispersion 0.49 dex. The metallicity distribution function is virtually identical to that found in other halo fields observed previously with HST, but with an enhanced metal-rich population that was partially missed in the previous surveys due to V-band incompleteness for these very red stars. Combining the metallicity-sensitive colors of the RGB stars with the metallicity- and age-sensitive features of the AGB bump and the red clump, we infer the average age of the halo stars to be ~8 Gyr. As part of our study, we present an empirical calibration of the ACS F606W and F814W filters to the standard V and I bands, achieved with ground-based observations of the same field made from the EMMI camera of the New Technology Telescope of the ESO La Silla Observatory.

Habitat selection and diet of the Capercaillie Tetrao urogallus in Abernethy Forest, Strathspey, Scotland

Capsule Woodland characteristics are important for fully grown birds and for broods. Aims To describe habitat selection and diet of the Capercaillie in ancient native pinewoods and Scots Pine Pinus sylvestris plantations, in order to provide a guide for forest management. Methods Tree selection was studied in winter by locating droppings under trees along transects, and comparing those trees used by Capercaillie with those not used. Habitat selection by broods was studied by following radiotagged chicks or females with broods. Diet was described from the analysis of droppings. Results In winter, Capercaillie preferred Scots Pines with wide crowns and large branches, and little surrounding Heather Calluna vulgaris, but avoided forest tracks. Female Capercaillie occurred in stands with a higher density of pines compared to males. The diet of fully grown birds comprised primarily Scots Pine needles between October and April. Scots Pine pollen cones were eaten during May, June and July. Bilberry Vaccinium myrtillus leaves and fruit were eaten in summer and autumn. Habitats used by broods had a higher percentage of Vaccinium sp. and smaller Scots Pines compared with random sites. Chicks hatch at the beginning of June, and in their first two weeks, their diet comprised Formicidae, Lepidoptera larvae and Coleoptera. In July and August, Lepidoptera larvae were rarely eaten but a higher percentage of chicks took vegetable material (particularly Bilberry fruit). In June, smaller numbers of invertebrates were generally trapped in mires of wooded bogs compared with areas of Heather and Vaccinium sp. in old woodland. Areas of Vaccinium sp. had the highest numbers of Formicidae, Coleoptera and Diptera, and especially Lepidoptera larvae. Numbers of Lepidoptera larvae declined during June and July as larvae pupated, explaining the reduction of Lepidoptera larvae in the diet of older chicks. Conclusions Habitat management for Capercaillie should aim to provide old Scots Pine forest with a Vaccinium-rich field layer. Within Scotland, this may entail increasing the tree density in ancient native pinewoods but decreasing it in pine plantations. The removal or closure of tracks might increase the amount of woodland available to Capercaillie, by reducing human disturbance.

Plant structural defences against browsing birds: a legacy of New Zealand's extinct moas

Browsing by large vertebrates has been a major force in the evolution of terrestrial plants but Holocene extinctions of the browsers have left a legacy of broken biotic partnerships. Ratite birds were the largest herbivores in several regions, such as the moas of New Zealand. Many woody plants there have a distinct form of branching, described as “divaricate”, with thin, wide angled, branches intertwining to form a tangled canopy. Divaricate branching has been interpreted as a form of protection against climate extremes or as an anachronistic defense against the extinct moas. Here we report the first experimental evidence that many of these plants are defended against extant ratite browsers. In feeding experiments on two tree species with different (heteroblastic) juvenile and adult branch morphology, emus and ostriches obtained adequate feeding rates from adult shoots but sub‐maintenance feeding rates from juvenile shoots with the ratite‐resistant traits. Divaricate juvenile shoots suffered 30–70% less biomass removal to the birds than adult shoots. Ratites browse by a distinctive clamping and tugging action. Structural defence traits that exploit the limitations of this feeding mode include narrow, strong, elastic branches that resist being torn off, wide branching angle (“divaricate”) that makes shoots difficult to swallow, and small, widely spaced leaves. This novel plant architectural defence has developed in at least 20% of the native woody flora of New Zealand, including 10 heteroblastic tree species that exhibit the ratite‐resistant strategy until they reach ca 3 metres height. It is also a major axis of variation amongst homoblastic woody shrub species. The defences are useless against mammalian browsers that shear shoots, contributing to marked decreases in the abundances of ratite‐resistant species in New Zealand after the introduction of mammals.

Bill dimorphism and foraging niche partitioning in the green woodhoopoe

Summary Cooperatively breeding green woodhoopoes, Phoeniculus purpureus, forage mainly as close‐knit groups, creating opportunities for intrasexual and intersexual foraging competition. Adult males foraged on wider branches than adult females, probably as a consequence of their larger body size (5–8%). Moreover, adult males spent more time scaling bark and probing the ends of broken branches, while adult females preferred pecking. There was no intersexual difference in the use of hole probing or surface gleaning. Intersexual differences in foraging technique probably resulted from morphological differences: adult male bills were 36% longer than those of females, with no overlap between the sexes. In support of the specialization hypothesis: (a) birds were more likely to forage in close proximity to a member of the opposite sex; (b) there was more intrasexual than intersexual aggression during foraging; (c) lone females did not change their foraging behaviour from when in close proximity to a male; (d) the niche breadth of both sexes was similar; and (e) juveniles foraged in ways predicted from their bill lengths. On fledging, bills of juvenile males and females were the same length as those of adult females, and all juveniles fed like adult females. After 4 months, the bills of juvenile males exceeded those of adult females, and they began to forage like adult males. Adult males brought different invertebrate taxa and heavier prey to the nest than females. These differences were a consequence of the different foraging techniques used, because both sexes collected the same types of prey when using the same technique. When all group members foraged together, dominant adults spent more time hole probing than subordinates of the same sex. This intrasexual difference probably resulted from interference competition, as dominants and subordinates did not differ in bill length, and dominants excluded subordinates from prime feeding areas. To compensate, subordinate adults did not increase their foraging time or collect larger prey items than dominants, but more often left the group to forage alone. When alone, subordinates spent more time hole probing and experienced higher foraging success than when in a group.

Reinvestigation of Nystroemia pectiniformis Halle, an enigmatic seed plant from the Upper Permian of China

Reinvestigation of Nystroemia pectiniformis Halle from the Upper Shihhotze Formation of Shanxi Province, China, has led to the identification of new and important features of this enigmatic Late Permian seed plant, permitting its typification and diagnosis. After reassembling several of the previously studied specimens to form a single articulated branching system comprising at least four orders of branching, previously unknown features of its branching pattern and morphology have been characterized. First–order axes are wide and branch to one side only, bearing second–order branches either singly or in pairs and of two kinds: one fertile and bearing characteristic ovulate branching systems and the other presumably vegetative. Ovulate second–order axes are narrow and branch to one side only, producing numerous, closely spaced lateral branches in two alternate to sub–opposite rows. Lateral branches are slender and produce numerous ovulate branching systems to one side of the axis only. Ovulate branching systems divide unequally to produce 3–15 ultimate axes of different lengths that are planated. Each ultimate axis bears a single terminal ovule with 180 degree rotational symmetry and two horn–like integumentary projections distally. The other kind of second–order axes are distinct from those bearing ovules; they are wider and longer and branches occur on both sides of the secondary axis, lacking divisions in close proximity to the first–order axis. These have only been observed incomplete although their distinct morphology indicates they are unlikely to be ovulate branches from which ovules/seeds have been shed. Additional organs of the Nystroemia plant are considered, including pollen organs previously assigned by Halle to the same species (displaying its characteristic branching style), and also leaves of Chiropteris reniformis Halle that were probably borne on the larger kind of second–order branches. Implications of Nystroemia on seed plant evolution and distribution are discussed, and it is concluded that this most likely represents a late stratigraphic occurrence of a plesiomorphic hydrasperman–type seed plant with affinities closely allied to members of the Lyginopteridales.

Conduction latency along CA3 hippocampal axons from rat.

Relatively few physiological studies have been carried out on intrahippocampal axons. We have recorded compound potentials from fiber groups and the activity of individual axons at 22-25 degrees C to characterize the conduction in subsets of the broad fan-shaped CA3 pyramidal axonal tree, including the Schaffer collaterals and longitudinal branches. The same wide axonal branching was indicated by antidromic activation of individual CA3 pyramidal cells. The average compound action potential latency from the CA3 to the CA1 area (Schaffer collaterals) increased by 4.16 +/- 0.06 ms/mm separation between the stimulation and registration electrodes. The impulses spread 31% faster in the 45-degree oblique temporal than in the transverse direction across CA1. The latency of the longitudinal axons in the CA3 area increased by 6.19 +/- 0.19 ms/mm. More impressive than these direction-dependent differences in latency were the large differences between individual axons running in the same direction. For both the longitudinal axons and the Schaffer collaterals, there was a broad distribution of antidromic latencies for a given distance between the stimulation and recording points. Typically, the fastest impulses arrived in half the time of the slowest. The distribution of compound action potential latencies between two points in the tissue could be made narrower by surgical restriction of the thickness and width of the preparation. By comparison, the cerebellar parallel fibers showed a narrower distribution of their latencies than the Schaffer collaterals. Because the cerebellar fibers run more straight than Schaffer collaterals, this suggested that some of the latency differences of the latter were due to differences in the path length of the axons. One consequence of our findings is that synchronous firing of neighboring CA3 pyramidal cells does not necessarily give synchronous inputs to common target CA1 neurons.

Turning around state-owned banks in underserved markets

Many state-owned retail banks in developing countries do not operate profitably and are reliant on repeated financial bail-outs from their governments and from donors. Given this situation, donors are often more inclined to invest in new MFIs than to attempt to revive problematic old ones. However, this article describes how external teams may be brought in to manage the restructuring of state-owned retail banks with some success. Two cases are described, Microfinance Bank of Tanzania and the Agricultural Bank of Mongolia. In both cases the banks' wide branch network was seen as a useful asset through which profitable new products and services could be sold to rural clients. The article describes the restructuring in each case, outlines the pre-conditions for successful restructuring of this kind (including a commitment on the part of the government to privatization of the bank), and discusses the lessons learned.

The Opposition Effect and Negative Polarization of Structural Analogs for Planetary Regoliths

To better understand the negative polarization and brightness opposition effects observed on airless celestial bodies, we carried out simultaneous photometric and polarimetric measurements of laboratory samples that simulate the structure of planetary regoliths. Computer modeling of shadow-hiding and coherent backscatter in regolith-like media are also presented. The laboratory investigations were carried out with a photometer/polarimeter at phase angles covering 0.2°–4° and wavelengths of 0.63 and 0.45 μm. We studied samples that characterize a variety of microscopic structures and albedos. A particle-size dependence of the negative branch of polarization for powdered dielectric surfaces was found. Colored samples such as a powder Fe 2O 3 exhibit a very prominent wavelength dependence of the photometric and polarimetric opposition phenomena. Metallic powders usually exhibit a wide branch of the negative polarization independent of the size of particles. For fine dielectric powders, both opposition phenomena become more prominent when the samples were compressed. Our computer modeling based on ray tracing in particulate media shows that shadow-hiding affects the negative polarization only in combination with the coherent backscatter enhancement. Modeling reveals that scattering orders higher than second contribute to negative polarization even in dark particulate surfaces. Our model qualitatively reproduces the effects of varying sample-compression that we observed in the laboratory. Our experimental and computer modeling studies mutually confirm that the degree of polarization for highly reflective dielectric surfaces depends not only on phase angle but also on surface tilt. Even at exactly zero phase the degree of polarization for tilted surfaces can be nonzero. A tilt of the surface normal to the scattering plane gives a parallel shift of the negative polarization branch to large values of | P|. The tilt in the perpendicular plane gives the same shift in the direction of positive polarization. At exactly zero phase angle, a celestial body of irregular shape can exhibit nonzero polarization even in integral polarimetric observations.

Three-dimensional laboratory modelling of rifting: application to the Baikal Rift, Russia

Continental rifting is treated as a mechanical instability developing under horizontal tectonic tension. The instability results in strain localization and the formation of a neck, which is interpreted as a rift zone. At the scale of the whole lithospheric plate, this process occurs in plane-stress conditions and can therefore be modelled to a first approximation by a one-layer plate whose properties represent integral (over thickness) properties of the real lithosphere. We have designed a scaled experimental single-layer lithosphere model having elasto-plastic rheology and lying upon a liquid substratum to study its behaviour under axial horizontal tension. In a homogeneous plate, the instability develops along a linear zone oriented at an angle of ∼60° to the tension axis. This orientation is preserved even when the divergent displacement of the plate boundaries is not plain-parallel but rotational. In the latter case, the strain localization zone is rapidly propagating. When the plate length to width ratio is less than ∼2.5, the necking develops along two branches conjugated at an angle of about 120°, which is frequently observed in actual rift systems. If the model contains a local weak zone (hot spot or fault zone), the rift junction is located at this zone. In the lithospheric models comprising strong (cratonic) and weak segments, strain localization depends on the configuration of the boundary between different lithospheres. The necking starts to form within the weak segment in the vicinity of the cratonic promontories and propagates in opposite directions again at an angle of ca. 60° to the tension axis. In the models containing both a strong lithosphere and local weak zones, the rift configuration depends on their shape and relative positions, with necking always going through the weak zones. In a set of models, we have reproduced the geometry of the boundary between the Siberian craton and the thermally much younger (∼100 Ma) Sayan–Baikal lithosphere in the Baikal rift area. In these models, we were able to obtain the well-known three-branch configuration of the Baikal rift system only by introducing a weak zone in the area of Lake Baikal. Such a zone simulates the Paleozoic suture existing in this area. As in nature, two wide outer branches (eastern and western) are oblique to the regional tension axis, whereas the central one is narrow and orthogonal to the tension direction. In nature and in the model, rifting starts in the central branch corresponding to Lake Baikal. The modelling also predicts the formation of a fourth oblique ∼NS-trending branch to the south of Baikal. Although poorly expressed in the field, this branch has some seismotectonic and magmatic manifestations. The orientations of all four branches with respect to each other and with respect to the regional tension direction are remarkably similar in nature and in the model.

Structural evolution of the southernmost segment of the West European Variscides: the South Portuguese Zone (SW Iberia)

The South Portuguese Zone (SPZ) represents the southernmost unit of the Iberian Massif. It is mainly composed of three structural domains, from north to south, the Beja–Acebuches Ophiolitic Complex (BAOC), The Pulo do Lobo Antiform (PLA) and the Iberian Pyrite Belt (IPB).This study proposes a structural analysis of the Spanish part of the SPZ that allows us to point out two main kinds of deformation; one accommodated by early top-to-the-south and following sinistral strike-slip tectonics in the northern part of the SPZ and the other by top-to-the-south thrusting in a wide southern branch. This transition, underlining the strain partitioning, is analysed by lattice preferred orientation of quartz using the texture goniometry method. It shows that the deformation is accommodated in the PLA at low to middle temperature by basal and prismatic 〈a〉 slip. Quartz textures suggest increasing thermal conditions of deformation from thrust to strike-slip tectonics.Our work within the IPB allows us to present a sequence of deformation showing a primary south-verging ductile thrusting and coeval crustal thickening in response to the thin-skinned tectonics. The progressive deformation generated backthrusts while it turns shallower southward. These features are summarised in an interpretative cross-section of the SPZ that underlines the main structural style of deformation, the fore-mentioned southward propagating thin-skinned thrusts.

Four-Year Evaluation of Five Cultivars of Pyrus Calleryana

In November 1995, five cultivars of Callery pear (Pyrus calleryana: 'Aristocrat', 'Capital', 'Chanticleer', 'Redspire', and 'Whitehouse') were planted within parkinglot traffic islands at Livingston College, a Piscataway campus of Rutgers, The State University of New Jersey, U.S. During the next four years, the trees were observed each spring from bud break to flowering, and again each fall. Measurements of growth patterns as well as observational attributes of the cultivars were recorded. 'Aristocrat' flushed growth a few days earlier than the others, occasionally suffering frost damage to flowers. Its vertical growth was slower when compared to the other cultivars, with a wider branch angle, a distinctly lower, broader crown, and a deep purple-red fall color in contrast to the orange-reds of the other cultivars. 'Aristocrat' was the only cultivar in the study to display branch angle attachments necessary for storm resistance and growth success. 'Chanticleer' grew the fastest of the five and had the narrowest branch angles. 'Redspire' was intermediate in growth, somewhat open, with fairly narrow branch angles. 'Capital' and 'Whitehouse' were comparatively dense and heavy blooming; it was difficult to distinguish between them.

Nucleation and crystallization of blends of poly(propylene) and ethylene/α-olefin copolymers

In this work, the nucleation and crystallization of immiscible blends of poly(propylene) (PP) with ethylene/α-olefin copolymers of different branching contents (Linear Low Density Poly(ethylene), LLDPE, Very Low Density Poly(ethylene), VLDPE, and Ultra Low Density Poly(ethylene), ULDPE) were studied. Melt-mixed blends of LLDPE/PP, VLDPE/PP and ULDPE/PP were prepared covering a wide composition range by means of twin screw extrusion. Additionally, blends containing 0.1% of the nucleating agent Sorbitol were prepared. The thermal behaviour of the blends was studied by means of Differential Scanning Calorimetry (DSC) whereas the morphology was investigated by means of Scanning Electron Microsopy. When PP droplets constituted the dispersed phase of the blends, fractionated crystallization of the PP component lead to coincident crystallization with the ethylene/α-olefin matrix, regardless of the branch content of the copolymer. This complex crystallization process occurred when a small fraction of PP droplets initiated the crystallization upon cooling, causing nucleation of the ethylene/α-olefin copolymer matrix and subsequently simultaneous crystallization of the rest of the PP droplets and the matrix. The fractionated crystallization process disappears if nuclei capable of being active at low supercooling are injected in any of the blends. The injection of nuclei was achieved by the use of sorbitol (a powerful nucleating agent for α-PP) or by self-nucleation of the PP component. When PP constituted the matrix in the blends, a nucleation process of the ethylene/α-olefin copolymers was observed. The nucleation of the ethylene/α-olefin copolymers by PP, sorbitol or PP/sorbitol mixture was found to be particularly effective for the most linear chains within the wide chain branching distribution present in these copolymers. A peculiar synergistic nucleation effect on LLDPE was produced by the addition of a mixture of PP and sorbitol. Even the addition of 1% PP and 0.1% sorbitol was enough to produce a very strong nucleation effect on the LLDPE, only comparable to that caused by self-nucleation.

Two new species of Gelidium (Rhodophyta, Gelidiales), Gelidium tenuifolium and Gelidium koshikianum, from Japan

SUMMARY Two new marine red algae, Gelidium tenuifolium sp. nov. and Gelidium koshikianum sp. nov. (Gelidiales, Gelidiaceae) are described from Japan. Gelidium tenuifolium with large-sized thalli (up to 30 cm tall) is distinguished from other species with such thalIi by the production of wide, flattened and thin branches (up to 2 mm wide and 60–80 urn thick), the presence of an apical depression and simple determinate branches. Gelidium koshikianum with middle-sized thalli (5–8 cm tall) is distinguished from other species with such thalli by having wide axes (up to 2.5 mm wide) and short (2.0–3.2 mm), unbranched, second- and third-order branches issuing at short intervals (0.8–1.4 mm). In phylogenetic analyses of rbcL sequences, four Gelidium species that are chiefly distributed in Japan including G. tenuifolium were clustered together with 99% bootstrap value (Japanese Gelidium-complex clade). Gelidium linoides Kutzing came to the position of the sister group to G. tenuifolium with 99% bootstrap value. There were four substitutions (0.3% divergence) between G. linoides and G. tenuifolium sequences. Gelidium koshikianum and Gelidium allanii Chapman were clustered together with 100% bootstrap value and they came to the position of the sister group to the Japanese GeIidium-complex clade with 83% bootstrap value. There were six substitutions (0.4% divergence) between G. koshikianum and G. allanii sequences.

Exact Detection of Arterial and Portal Branches of the Terminal Afferent Vessels in the Rat Liver By Means of Corrosion Casts and Edx

The physiological necessity of the dual afferent blood supply of the liver and the morphological features of the macrocirculation are well understood. The microcirculation, however, still poses a number of unsolved questions. In particular the nature of the terminal junctions of the arterial and portal blood stream with the sinusoids has so far not been satisfactorily elucidated (1-2). Scanning electron microscopy alone or in combination with corrosion casts cannot solve the problem, because it remains difficult to tell the different vessels apart. Under favorable circumstances the terminal portal vein is the easiest to be distinguished with corrosion casts. This is due to the fact that its relatively wide branches surround the classical liver lobules along the major parts of their circumference. The diameter of the terminal hepatic artery is in its initial segments not as wide as the initial segments of the terminal portal vein.

An unusual course of the right renal artery associated with an anomalous inferior vena cava

In a 55-year-old male cadaver, the inferior vena cava bifurcated at a level midway between the hilus and inferior pole of the right kidney. The narrower branch, on the right side, drained the right renal and hepatic veins, ascended as the normal inferior vena cava, passed through the caval opening of the diaphragm and drained into the right atrium. The wider branch on the left side drained the left renal vein and penetrated the right crus of the diaphragm as the azygos vein. This vein ascended in the posterior mediastinum and drained into the superior vena cava. The hemiazygos and accessory hemiazygos veins were absent. In addition to these anomalies, the right renal artery entered the hilus after coursing through the above-mentioned two branches at the bifurcation. No congenital anomalies of the heart or abdominal viscera and main arteries were seen.

Water flow and prey capture by three scleractinian corals, Madracis mirabilis , Montastrea cavernosa and Porites porites , in a field enclosure

Scleractinian corals experience a wide range of flow regimes which, coupled with colony morphology, can affect the ability of corals to capture zooplankton and other particulate materials. We used a field enclosure oriented parallel to prevailing oscillatory flow on the forereef at Discovery Bay, Jamaica, to investigate rates of zooplankton capture by corals of varying morphology and polyp size under realistic flow speeds. Experiments were carried out from 1989 to 1992. Particles (Artemia salina cysts) and naturally occurring zooplankton attracted into the enclosures were used as prey for the corals Madracis mirabilis (Duchassaing and Michelotti) (narrow branches, small polyps), Montastrea cavernosa (Linnaeus) (mounding, large polyps), and Porites porites (Pallas) (wide branches, small polyps). This design allowed corals to be used without removing them or their prey from the reef environment, and avoided contact of zooplankton with net surfaces. Flow speed had significant effects on capture rate for cysts (M. mirabilis), total zooplankton (M. mirabilis, M. cavernosa), and non-copepod zooplankton (M. mirabilis). Zooplankton prey capture increased with prey concentration for M. mirabilis and M. cavernosa, over a broad range of concentrations, indicating that saturation of the feeding response had not occurred until prey density was over 104 items m−3, a concentration at least an order of magnitude greater than the normal range of reef zooplankton concentrations. Location of cyst capture on coral surfaces was not uniform; for M. cavernosa, sides and tops of mounds captured most particles, and for P. porites, capture was greatest near branch tops, but was close to uniform for M. mirabilis branches in all flow conditions. The present study confirms laboratory flume results, and field results for other species, suggesting that many coral species experience particle flux and encounter rate limitations at low flow speeds, decreasing potential zooplankton capture rates.