Transfer Learning and Meta Learning Based Fast Downlink Beamforming Adaptation

This paper studies fast adaptive beamforming optimization for the signal-to-interference-plus-noise ratio balancing problem in a multiuser multiple-input single-output downlink system. Existing deep learning based approaches to predict beamforming rely on the assumption that the training and testing channels follow the same distribution which may not hold in practice. As a result, a trained model may lead to performance deterioration when the testing network environment changes. To deal with this task mismatch issue, we propose two offline adaptive algorithms based on deep transfer learning and meta-learning, which are able to achieve fast adaptation with the limited new labelled data when the testing wireless environment changes. Furthermore, we propose an online algorithm to enhance the adaptation capability of the offline meta algorithm in realistic non-stationary environments. Simulation results demonstrate that the proposed adaptive algorithms achieve much better performance than the direct deep learning algorithm without adaptation in new environments. The meta-learning algorithm outperforms the deep transfer learning algorithm and achieves near optimal performance. In addition, compared to the offline meta-learning algorithm, the proposed online meta-learning algorithm shows superior adaption performance in changing environments

[μ-10,21-Dimethyl-3,6,14,17-tetra­za­tricyclo­[17.3.1.18,12]tetra­cosa-1(23),2,6,8,10,12 (24),13,17,19,21-deca­ene-23,24-diolato-κ4 N 3,N 6,O 23,O 24:κ4 N 14,N 17,O 23,O 24]bis­(perchlorato-κO)dimanganese(II)

In the centrosymmetric and dinuclear title complex, [Mn2(C22H22N4O2)(ClO4)2], the two Mn atoms are bridged by two phenolate O atoms of the N4O2 macrocycle with an Mn⋯Mn distance of 2.9228 (11) Å. The distorted square–pyramidal N2O3 coordination geometry is completed by an O atom derived from a perchlorate anion

Tetra-μ-benzoato-κ8 O:O′-bis­[(benzoic acid-κO)nickel(II)]

The title compound, [Ni2(C7H5O2)4(C7H6O2)2], is composed of two NiII ions, four bridging benzoate anions and two η1-benzoic acid mol­ecules. The [Ni2(PhCOO)4] unit adopts a typical paddle-wheel conformation. The center between the two NiII atoms represents a crystallographic center of inversion. In addition, each NiII ion also coordinates to one O atom from a benzoic acid mol­ecule. The crystal packing is realised by inter­molecular hydrogen-bonding inter­actions and π–π stacking inter­actions, with a centroid–centroid distance of 3.921 (1) Å

Bis(μ-4-fluoro-2,6-diformyl­phenolato)bis­[diaqua­nickel(II)] dichloride

In the title dinuclear nickel(II) complex, [Ni2(C8H4FO3)2(H2O)4]Cl2, synthesized by the reaction between 4-fluoro-2,6-diformyl­phenol and nickel(II) chloride in methanol, the coordination cation is located on an inversion center and the NiII atom adopts a slightly distorted octa­hedral coordination geometry. The two Ni atoms are bridged by two phenolate O atoms and the intra­molecular Ni⋯Ni distance is 3.0751 (9) Å. The crystal structure is stabilized by O—H⋯Cl hydrogen bonds

Vapourchromic alkali metal ions complexes based on 2-phenmethylamino-7-methyl-1,8-naphthyridine

556-560A series of 2-phenmethylamino-7-methyl-1,8-naphthyridine/alkali metal ion (Li+ and Na+) complexes have been synthesized using a polymeric medium (poly(acrylic acid)) as the key activating component. Upon exposure to methanol or ethanol vapour at ambient temperature, the emission colour of prepared complexes in solid powder and thin film states changes from red-orange or pink to blue, respectively. These phenomena are reversible and rapid (about 5-10 s), hence, the prepared complexes have potential applications as chemosensor materials for detection of volatile methanol vapour

Magnolia compressa Zhongshanhanxiao: A New Magnolia L. Cultivar (Magnoliaceae)

Magnolia compressa Zhongshanhanxiao, a new Magnolia compressa (Maxim.) Sarg. cultivar, is described and illustrated in this paper. The leaves and flower of M. compressa ‘Zhongshanhanxiao’ were similar to M. compressa (Maxim.) Sarg., but differed from the latter by their larger sizes. The leaf lengths and widths of the new cultivar were 7 to 15 cm and 3 to 7 cm, respectively [the leaf lengths and widths of M. compressa (Maxim.) Sarg. were 5 to 7 cm and 2 to 3 cm, respectively], and the perianth lengths and widths were 4 to 7 cm and 1 to 4 cm, respectively [the perianth lengths and widths of M. compressa (Maxim.) Sarg. were 1.2 to 1.5 cm long and 0.3 to 0.5 cm wide]. In addition to the morphological differences, the new cultivar had a faster growth rate and the first flowering time was the third year after planting, whereas M. compressa (Maxim.) Sarg. took longer to first flower. The flowering period of this new cultivar was from February to March and the fruiting period was from October to November

Mitochondrial and nuclear ribosomal DNA dataset supports that Paramphistomum leydeni (Trematoda: Digenea) is a distinct rumen fluke species

BACKGROUND: Rumen flukes parasitize the rumen and reticulum of ruminants, causing paramphistomiasis. Over the years, there has been considerable debate as to whether Paramphistomum leydeni and Paramphistomum cervi are the same or distant species. METHODS: In the present study, the complete mitochondrial (mt) genome of P. leydeni was amplified using PCR-based sequencing and compared with that of P. cervi. The second internal transcribed spacer (ITS-2) of nuclear ribosomal DNA (rDNA) of P. leydeni specimens (n = 6) and P. cervi specimens (n = 8) was amplified and then sequenced. Phylogenetic relationship of the concatenated amino acid sequence data for 12 protein-coding genes of the two rumen flukes and selected members of Trematoda was evaluated using Bayesian inference (BI). RESULTS: The complete mt genome of P. leydeni was 14,050 bp in size. Significant nucleotide difference between the P. leydeni mt genome and that of P. cervi (14.7%) was observed. For genetic divergence in ITS-2, sequence difference between P. leydeni and P. cervi was 3.1%, while no sequence variation was detected within each of them. Phylogenetic analysis indicated that P. leydeni and P. cervi are closely-related but distinct rumen flukes. CONCLUSIONS: Results of the present study support the proposal that P. leydeni and P. cervi represent two distinct valid species. The mt genome sequences of P. leydeni provide plentiful resources of mitochondrial markers, which can be combined with nuclear markers, for further comparative studies of the biology of P. leydeni and its congeners from China and other countries. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s13071-015-0823-4) contains supplementary material, which is available to authorized users

Anisotropic g factors of the tetragonal Cu²⁺ monomer in Tl-2223 superconductor

The gyromagnetic factors of the Cu²⁺ monomer in Tl-2223 superconductor are quantitatively investigated from the perturbation formulas of these factors for a 3d⁹ ion in a tetragonally elongated octahedron. The local tetragonal distortion of the system is attributable to the axial elongation along c axis, corresponding to the five-fold coordinated Cu²⁺(2) site with almost 30% longer Cu–O bond length for the apical oxygen as compared to the four planar ones. The significant anisotropic behaviors of the EPR spectra perpendicular to and parallel with the ab (CuO₂) layers are analyzed on the basis of the local tetragonal elongation