Small Compact Clusters Research Articles

НОВЫЙ ИНТРОДУЦИРОВАННЫЙ СОРТ ВИНОГРАДА TICKLED PINK

This article presents the varietal study and evaluation of a new introduced grapevine variety Tickled Pink of the USA breeding, obtained as part of the Breeding Program of the University of Arkansas in the conditions of ARRIV&W – Branch of the FSBSI FRARC. An ampelographic description of the variety was made according to the main characteristics. This grapevine cultivar can be distinguished by its seedless berries, similar to Vitis labrusca L. morphological features and taste of berries, small compact clusters, wedge-shaped leaves, medium vigor, and disease and cold-hardiness. The vineyards are not watered, grafted, not covered, the two-armed middle-trunk cordon bush shape, the planting scheme is 3×1.5 m, the pruning is short. Methods generally accepted in viticulture and standard vineyard cultivation technology were used. According to our data, the Tickled Pink variety has an super-early terms of grape ripening (105 days from bud break to full ripeness of berries), small bunches with an average weight of 90.5 g, medium-sized berries with a weight of 2.2 g, seedlessness class II (mass of rudiments 8.7 mg), high resistance to downy mildew, anthracnose and botrytis, medium resistance to powdery mildew. According to the originators, the variety is highly resistant to frost, which we could not confirm due to the lack of critical low temperatures in winter, but it was possible to note the high winter hardiness of the variety. Yield is low, 4.7 t/ha. We believe that the grape cultivar Tickled Pink is not quite suitable for our terroir due to insufficient drought resistance and heat resistance, but it can be recommended for backyard gardening in regions with a cool climate, as well as for use in the breeding of resistant seedless grape varieties.

LERI: Local Exploration for Rare-Category Identification

To identify the data examples of rare categories that form small compact clusters in large data sets, existing approaches mostly require enough labeled data examples as a training set to learn a classifier, assuming that the rare-category clusters are spherical or nearly spherical. Nonetheless, a large enough training set is usually difficult to obtain in practice, and rare categories in many real-world applications often form small compact clusters with arbitrary shapes. In this paper, we investigate how to identify all data examples of a rare category with an arbitrary shape based on only one seed (i.e., a labeled rare-category data example). Instead of finding a compact and spherical local region around the seed, we locally explore the data set from the seed by continuously searching and visiting the $k$ k -nearest neighbors of each newly visited data example. The local exploration connects the data examples in the objective rare category by the relationship of $k$ k -nearest neighbors, and meanwhile, suspected external data examples are filtered out if they are not close enough to any visited data example. Experimental results on both synthetic and real-world data sets are conducted, and the results verify the effectiveness and efficiency of our approach.

Complex trend of magnetic order in Fe clusters on4dtransition-metal surfaces. II. First-principles calculations

We use first-principles calculations based on density functional theory to investigate the magnetic exchange interaction of Fe clusters on Rh(111) and Ru(0001). We consider dimers, trimers, tetramers, and pentamers of different shape in fcc and hcp stacking as well as infinite atomic and biatomic chains. From the dimer calculations, we extract the exchange interaction as a function of adatom distance by mapping total energies to a Heisenberg model. The nearest-neighbor (NN) exchange constant is about one order of magnitude smaller than reported for other substrates due to the strong hybridization between the Fe atoms and the partly filled $4d$ band of the surface. We also find a transition from a ferromagnetic NN exchange interaction for Fe dimers on Rh(111) to an antiferromagnetic one on Ru(0001). The distance-dependent exchange coupling displays a RKKY-like oscillatory behavior, which is nearly inverted for Fe dimers on the Rh(111) surface compared to those on Ru(0001). Unexpectedly, for Fe clusters beyond dimers, a complex trend of the magnetic ground state is observed which alternates between ferro- and antiferromagnetic configurations depending on cluster size and shape. In view of the exchange constants obtained for dimers, it is surprising that on both surfaces small compact clusters are ferromagnetic while open structures such as linear trimers or tetramers become antiferromagnetic. We demonstrate that both vertical and lateral structural relaxations of the clusters are crucial in order to understand this unexpected trend of magnetic order and connected to the competition of direct ferromagnetic exchange among Fe atoms in the cluster and the hybridization with the substrate.

Hydrogen bonding in liquid methanol, methylamine, and methanethiol studied by molecular-dynamics simulations

Molecular-dynamics computer simulations have been carried out on liquid methanol, methylamine, and methanethiol. The local structure of the liquids was studied based on radial distribution functions and the density projections of the neighboring molecules obtained on the basis of simulated molecular configurations. The extent of hydrogen bonding was investigated by direct analysis of the connectivity of molecules forming hydrogen-bonded clusters in these liquids. By this analysis, the methanol molecules were found to form linear chainlike structures. The local structure of hydrogen-bonded molecules of methylamine proved to be rather space filling due to the great extent of chain branching. Methanethiol molecules also proved to form hydrogen bonds forming small compact clusters. No evidence was found, however, for the clustering of hydrophobic methyl groups in any of the liquids. The quality of simulations was checked by derivation of neutron total and composite radial distribution functions and by comparison of those with available experimental data.

Growth of precursors in silicon using pseudopotential calculations.

Based on the results of pseudopotential calculations, the progression of a single interstitial into small compact clusters and ultimately into chain-like defects is examined. For clusters that consist of more than eight interstitials, the capture of bond-centered interstitials reveals a change in the growth mechanism leading to enhanced stability of clusters. The five-interstitial model is proposed to be a plausible candidate for optically active W centers, observed in ion irradiated silicon.

On the dynamics of the [formula omitted] Ising model in a transverse field

A new solution for the spin- 1 2 Ising model in an external transverse field for the case of three-dimensional nearest-neighbor interactions is obtained. The chain of equations for high-order Green functions is decoupled in the scope of symmetrized Tyablikov's scheme and consistently reduced to a closed equation system, which is solved exactly. This improves previous relevant solutions by short-range quantum correlation effects caused by spins involved in small compact clusters and suggests a new dynamic description of the paramagnetic phase of ferroelectrics, to which the model is directly applied.