Tree Inscriptions: restoring a lost facet of the Graeco-Roman epigraphic habit

This article for the first time considers all extant ancient evidence for the habit of carving inscriptions on tree trunks. It emerges a picture that bears remarkable resemblances to what is known from the habit of graffiti writing (with important addition to that latter field to be derived from the findings), for individual and technical texts.

Dynamic load balancing in parallel KD-tree k-means

One among the most influential and popular data mining methods is the k-Means algorithm for cluster analysis. Techniques for improving the efficiency of k-Means have been largely explored in two main directions. The amount of computation can be significantly reduced by adopting geometrical constraints and an efficient data structure, notably a multidimensional binary search tree (KD-Tree). These techniques allow to reduce the number of distance computations the algorithm performs at each iteration. A second direction is parallel processing, where data and computation loads are distributed over many processing nodes. However, little work has been done to provide a parallel formulation of the efficient sequential techniques based on KD-Trees. Such approaches are expected to have an irregular distribution of computation load and can suffer from load imbalance. This issue has so far limited the adoption of these efficient k-Means variants in parallel computing environments. In this work, we provide a parallel formulation of the KD-Tree based k-Means algorithm for distributed memory systems and address its load balancing issue. Three solutions have been developed and tested. Two approaches are based on a static partitioning of the data set and a third solution incorporates a dynamic load balancing policy.

Efficient tree construction for the multicast problem

A new heuristic for the Steiner Minimal Tree problem is presented here. The method described is based on the detection of particular sets of nodes in networks, the “Hot Spot” sets, which are used to obtain better approximations of the optimal solutions. An algorithm is also proposed which is capable of improving the solutions obtained by classical heuristics, by means of a stirring process of the nodes in solution trees. Classical heuristics and an enumerative method are used CIS comparison terms in the experimental analysis which demonstrates the goodness of the heuristic discussed in this paper.

Efficient tree construction for the multicast problem

A new heuristic for the Steiner minimal tree problem is presented. The method described is based on the detection of particular sets of nodes in networks, the “hot spot” sets, which are used to obtain better approximations of the optimal solutions. An algorithm is also proposed which is capable of improving the solutions obtained by classical heuristics, by means of a stirring process of the nodes in solution trees. Classical heuristics and an enumerative method are used as comparison terms in the experimental analysis which demonstrates the capability of the heuristic discussed

Spectral functions of half-filled one-dimensional Hubbard rings with varying boundary conditions

We study the effect of varying the boundary condition on: the spectral function of a finite one-dimensional Hubbard chain, which we compute using direct (Lanczos) diagonalization of the Hamiltonian. By direct comparison with the two-body response functions and with the exact solution of the Bethe ansatz equations, we can identify both spinon and holon features in the spectra. At half-filling the spectra have the well-known structure of a low-energy holon band and its shadow-which spans the whole Brillouin zone-and a spinon band present for momenta less than the Fermi momentum. Features related to the twisted boundary condition are cusps in the spinon band. We show that the spectral building principle, adapted to account for both the finite system size and the twisted boundary condition, describes the spectra well in terms of single spinon and holon excitations. We argue that these finite-size effects are a signature of spin-charge separation and that their study should help establish the existence and nature of spin-charge separation in finite-size systems.

On the fast decay of Agulhas rings

The Indian Ocean water that ends up in the Atlantic Ocean detaches from the Agulhas Current retroflection predominantly in the form of Agulhas rings and cyclones. Using numerical Lagrangian float trajectories in a high-resolution numerical ocean model, the fate of coherent structures near the Agulhas Current retroflection is investigated. It is shown that within the Agulhas Current, upstream of the retroflection, the spatial distributions of floats ending in the Atlantic Ocean and floats ending in the Indian Ocean are to a large extent similar. This indicates that Agulhas leakage occurs mostly through the detachment of Agulhas rings. After the floats detach from the Agulhas Current, the ambient water quickly looses its relative vorticity. The Agulhas rings thus seem to decay and loose much of their water in the Cape Basin. A cluster analysis reveals that most water in the Agulhas Current is within clusters of 180 km in diameter. Halfway in the Cape Basin there is an increase in the number of larger clusters with low relative vorticity, which carry the bulk of the Agulhas leakage transport through the Cape Basin. This upward cascade with respect to the length scales of the leakage, in combination with a power law decay of the magnitude of relative vorticity, might be an indication that the decay of Agulhas rings is somewhat comparable to the decay of two-dimensional turbulence.

Comparative analysis by protocol and key of seed storage behaviour of sixty Vietnamese tree species

Seed storage behaviour of 5 1 native and 9 introduced tree species in Vietnam was investigated using a brief protocol developed to aid biodiversity conservation in circumstances where little is known about the seeds. Of the 60 species, 34 appeared to show orthodox (Acacia auriculaeformis, Adenanthera pavonina, Afzelia xylocarpa, Bauhinia purpurea, Callistemon lanceolatus, Cananga odorata, Canarium nigrum, Cassia fistula, Cassia javanica, Cassia splendida, Chukrasia tabularis, Dalbergia bariaensis, Dialium cochinchinensis, Diospyros mollis, Diospyros mun, Dracuntomelon duperreanum, Erythrophleum fordii, Khaya senegalensis, Lagerstroemia speciosa, Leucaena leucocephala, Livistona cochinchinensis, Markhamia stipulata, Melaleuca cajuputi, Millettia ichthyotona, Peltophorum pterocarpum, Peltophorum tonkinensis, Pinus khasya, Pinus massoniana, Pinus merkusii, Pterocarpus macrocarpus, Sindora siamensis, Sophora tonkinense, Sterculia foetida, Swietenia macrophylla), 13 recalcitrant (Avicennia alba, Beilschmiedia roxburghiana, Caryota mitis, Dimocarpus sp., Diospyros malabarica, Dipterocarpus chartaceus, Dypsis pinnatifrons, Hopea odorata, Lithocarpus gigantophylla, Machilus odoratissimus, Melanorrhoea laccifera, Melanorrhea usitata, Syzygium cinereum) and 13 intermediate (Anisoptera cochinchinensis, Aphanamixis polystachya, Averrhoa carambola, Carissa carandas, Chrysopylum cainito, Cinnamomum camphora, Citrofortunella microcarpa, Citrus grandis var. grandis, Elaeis guineensis, Hydnocarpus anthelmintica, Madhuca floribunda, Manilkara achras, Mimusops elengi) seed storage behaviour. A double-criteria key to estimate likely seed storage behaviour showed good agreement with the above: the key can reduce the workload of seed storage behaviour identification considerably.

Seed survival of four tropical tree species in response to environment

The response of seed survival to storage duration and environment (temperature and moisture content) in the four tropical tree species: Cedrela odorata L., Ceiba pentandra (L.) Gaertn., Dalbergia spruceana Benth. and Tabebuia alba (Cham.) Sandwith. from Amazonia conformed to the seed viability equation of Ellis and Roberts. Estimates of the seed viability constants to calculate seed longevity in these species are provided.

Chemical composition and in vitro fermentation of tannin-rich tree fruits

Dry and mature tree fruits are a potential source of protein for goats in the semi-arid areas of southern Africa, but their chemical composition and feeding value is largely unknown. This study presents the chemical composition and in vitro fermentation of indehiscent whole fruits and separated seed and hull fractions from Acacia nilotica, Acacia erubescens, Acacia sieberiana, Acacia erioloba, Piliostigma thonningii and Dichrostachys cinerea trees. Results indicate that the N contents of whole fruits ranged between 13.5 g/kg DM (A. nilotica) and 27.1 g/kg DM (A. erubescens). Seeds had a higher N content than hulls for all tree species. A. nilotica, D. cinerea and P thonningii fruits had high levels of extractable phenolics (758, 458 and 299 g/kg DM, respectively). Soluble phenolics (SPh) and ytterbium precipitable phenolics (YbPh) levels were negatively correlated to in vitro gas production but positively correlated to in vitro organic matter degradability (iOMD). Partition factors for whole fruits at 48 h ranged between 3.6 mg/ml for A. erioloba and 7.8 mg/ml for A. nilotica. Seeds of A. erioloba, A. erubescens and P thonningii were consistently fermented more efficiently throughout the incubation period compared to their whole fruits or hulls. Estimating in vitro degradability of phenolic-rich substrates through filtration procedures can give erroneous results due to the loss of soluble phenolics, which are not necessarily degradable. The feeding value of fruits from D. cinerea and A. nilotica tree species may be reduced due to the presence of high levels of phenolics. (C) 2007 Elsevier B.V. All rights reserved.

In vitro biological activity of tannins from Acacia and other tree fruits: Correlations with colorimetric and gravimetric phenolic assays

This Study was designed to investigate impact of tannins on in vitro ruminal fermentation parameters as well as relationships between concentration and in vitro biological activity of tannins present in tree fruits. Dry and mature fruits of known phenolic content harvested from Acacia nilotica, A. erubescens, A. erioloba, A. sieberiana, Piliostigima thonningii and Dichrostachys cinerea tree species were fermented with rumen fluid in vitro with or without polyethylene glycol (PEG). Correlation between in vitro biological activity and phenolic concentration was determined. Polyethylene glycol inclusion increased Cumulative gas production from all fruit substrates. The largest Increase (225%) after 48 h incubation was observed in D. cinerea fruits while the least (12.7%) increase was observed in A. erubescens fruits. Organic matter degradability (48 h) was increased by PEG inclusion for all tree species except A. erubescens and P. thonningii. For D. cinerea fruits, colorimetric assays were poorly correlated to Increases In gas production due to PEG treatment. Ytterbium precipitable phenolics (YbPh) were also poorly correlated with response to PEG for A. erioloba and P. thonningii fruits. However, YbPh were strongly and positively correlated to the increase In Cumulative gas production due to PEG for A. erubescens and A. nilotica. Folin-Ciocalteau assayed phenolics (SPh) were not correlated to response to PEG in P. thonningii and A. sieberiana. It was Concluded that the PEG effect oil in vitro fermentation was closely related to some measures of phenolic concentration but the relationships varied with tree species.

Chemical composition and in vitro ruminal fermentation of common tree forages in the semi-arid rangelands of Swaziland

Browse plants play an important role in providing feed for livestock in semi-arid rangelands of Africa. Chemical composition and in vitro ruminal fermentation of leaves collected from Acacia burkei, Acacia tortilis, Acacia nilotica, Dichrostachys cinerea and Ehretia obtusifolia in communal grazing lands in the lowveld of Swaziland is presented. Leaves were collected from trees located on two soil types (i.e., lithosol and vertisol) in the communal land but it had no effect on the chemical composition of tree leaves. The NDFom and ADFom content were highest in D. cinerea and A. burkei and lowest in E. obtusifolia and A. nilotica. Crude protein (CP) contents ranged between 108 g/kg and 122 g/kg DM. D. cinerea had the highest Ca and Mg content, while A. tortilis had the lowest. There were marked variations in K level amongst browse species, with A. tortilis (9.1 g/kg DM) having the highest value. The P, Zn and Fe did not differ between browse species. Soil type and tree species interaction impacted in vitro fermentation parameters. Extent of fermentation, as measured by 48 h cumulative gas production, and organic matter degradability was highest in E. obtusifolia leaves and lowest in D. cinerea leaves within soil type. Fermentation efficiency, as measured by partitioning factors, was highest in A. nilotica leaves. Leaves of E. obtusifolia could be a valuable supplementary feedstuff for ruminant livestock due to its in vitro fermentation characteristics as well as low fibre and moderate CP levels. (c) 2007 Elsevier B.V. All rights reserved.