Discrete No-Fit Polygon,A Simple Structure for the 2-D Irregular Packing Problem

提出了一个用于求解二维不规则排样问题的离散临界多边形模型.burkE等人的blf算法是求解排样问题的一种有效算法,但其算法对一些特殊实例会产生非法的解.为了解决这个问题,提出了一种基于离散临界多边形模型,并对其正确性作了严格证明.新模型是只含有点和区间的简单模型,在大大降低原问题几何复杂性的同时,也使许多启发式策略可以更容易地求解该问题.计算结果表明,基于离散临界多边型模型的排样算法是很有效的.This paper presents a model based on discrete no-fit polygon for the two-dimensional irregular packing problem.Burke et al.have presented an effective BLF algorithm to solve the irregular packing problem, however, their algorithm might generate invalid results for some special cases.To solve this problem, a model based on discrete no-fit polygon is proposed, and its correctness has been strictly proved.Only points and intervals are only considered by this model, which greatly decreases the geometry complexity of the original problem and makes the problem easily solved by many heuristic strategies.Computational results show that the algorithm based on discrete no-fit polygon model is very efficient.国家自然科学基金No.60773126;福建省自然科学基金No.A07100234;厦门大学985二期信息科技基金No.0000-X07204;厦门大学院士启动基金No.X01109---

Trends in bone metastasis modeling

Bone is one of the most common sites for cancer metastasis. Bone tissue is composed by different kinds of cells that coexist in a coordinated balance. Due to the complexity of bone, it is impossible to capture the intricate interactions between cells under either physiological or pathological conditions. Hence, a variety of in vivo and in vitro approaches have been developed. Various models of tumor\u2013bone diseases are routinely used to provide valuable information on the relationship between metastatic cancer cells and the bone tissue. Ideally, when modeling the metastasis of human cancers to bone, models would replicate the intra-tumor heterogeneity, as well as the genetic and phenotypic changes that occur with human cancers; such models would be scalable and reproducible to allow high-throughput investigation. Despite the continuous progress, there is still a lack of solid, amenable, and affordable models that are able to fully recapitulate the biological processes happening in vivo, permitting a correct interpretation of results. In the last decades, researchers have demonstrated that three-dimensional (3D) methods could be an innovative approach that lies between bi-dimensional (2D) models and animal models. Scientific evidence supports that the tumor microenvironment can be better reproduced in a 3D system than a 2D cell culture, and the 3D systems can be scaled up for drug screening in the same way as the 2D systems thanks to the current technologies developed. However, 3D models cannot completely recapitulate the inter-and intra-tumor heterogeneity found in patients. In contrast, ex vivo cultures of fragments of bone preserve key cell\u2013cell and cell\u2013matrix interactions and allow the study of bone cells in their natural 3D environment. Moreover, ex vivo bone organ cultures could be a better model to resemble the human pathogenic metastasis condition and useful tools to predict in vivo response to therapies. The aim of our review is to provide an overview of the current trends in bone metastasis modeling. By showing the existing in vitro and ex vivo systems, we aspire to contribute to broaden the knowledge on bone metastasis models and make these tools more appealing for further translational studies

Wave modelling - the state of the art

This paper is the product of the wave modelling community and it tries to make a picture of the present situation in this branch of science, exploring the previous and the most recent results and looking ahead towards the solution of the problems we presently face. Both theory and applications are considered. The many faces of the subject imply separate discussions. This is reflected into the single sections, seven of them, each dealing with a specific topic, the whole providing a broad and solid overview of the present state of the art. After an introduction framing the problem and the approach we followed, we deal in sequence with the following subjects: (Section) 2, generation by wind; 3, nonlinear interactions in deep water; 4, white-capping dissipation; 5, nonlinear interactions in shallow water; 6, dissipation at the sea bottom; 7, wave propagation; 8, numerics. The two final sections, 9 and 10, summarize the present situation from a general point of view and try to look at the future developments

Mainland and insular lacertid lizards

Lacertid lizards have long been a fruitful field of scientific enquiry with many people working on them over the past couple of hundred years. The scope of the field has steadily increased, beginning with taxonomy and anatomy and gradually spreading so that it includes such topics as phylogenetics, behaviour, ecology, and conservation. Since 1992, a series of symposia on lacertid lizards of the Mediterranean basin have taken place every three years. The present volume stems from the 2004 meeting in the Aeolian Islands. In the volume a wide range of island topics are considered, including the systematics of the species concerned, from both morphological and molecular viewpoints, interaction with other taxa, and conservation. The last topic is especially important, as island lizards across the world have often been vulnerable to extinction, after they came into contact with people and the animals they introduced. The volume also has papers on the more positive aspects of human influence, specifically the benign effects of traditional agriculture on at least some reptile species. Olive trees, cork oaks and the banks and walls of loose rocks that crisscross the Mediterranean scene all often contribute to elevated lizard populations. Nor is more basic biology neglected and there are articles on morphology, reproduction, development and thermoregulation. Finally, it is good to see one paper on non-Mediterranean species is included. For, to fully understand the lacertids of this region, it is necessary to appreciate their close relatives in Africa, Asia and the archipelagos of the northeastern Atlantic Ocean. (From Preface by E. Nicholas Arnold & Wolfgang Böhme

Systematic studies of the South African Campanulaceae sensu stricto with and emphasis on generic delimitations

The South African Campanulaceae sensu stricto, comprising 10 genera, represent the most diverse lineage of the family in the southern hemisphere. In this study two phylogenies are reconstructed using parsimony and Bayesian methods. A family-level phylogeny was estimated to test the monophyly and time of divergence of the South African lineage. This analysis, based on a published ITS phylogeny and an additional ten South African taxa, showed a strongly supported South African clade sister to the campanuloids. Assessment of divergence times using a secondary calibration point suggests that this clade started to diversify during the Oligocene (28 mya), which coincided with global climatic changes from hot wet to cold dry conditions. A phylogenetic analysis of the South African lineage was undertaken based on morphological and DNA sequence data from the chloroplast trnL-F and the nuclear ITS regions. These data sets were analyzed separately and in combination. The phylogenetic hypothesis was used to re-assess the questionable generic boundaries in the family. The ITS data produced poor resolution under parsimony and poor support under Bayesian methods. The resulting phylogenies show five species assemblages that contradict traditional generic circumscriptions, which have primarily been based on the mode of capsule dehiscence. The date estimated for the South African clade was used as calibration point to estimate the age of the clades revealed by the molecular data. Radiation of the Campanulaceae in southern Africa seems to correlate with dramatic climatic and topographical changes such as aridification and continental uplift on the subcontinent that started during the Oligocene. The phylogenetic hypothesis was also used to trace the evolution of nine characters considered important in the circumscription of genera. An uncontradicted synapomorphy was found for the Rhigiophyllum-Siphocodon clade. The fruit character was found to be taxonomically unreliable at the generic level. The phylogeny of the South African clade was further used to focus on the closely related genera, Roella, Merciera and Prismatocarpus â a group forming a well supported clade in most analyses. The total evidence analysis was used to evaluate the status of each of these genera. Several options were explored to translate the phylogeny into a classification. This process was guided by the primary criterion of monophyly followed by stability in nomenclature, strong statistical support for the taxon, maximum phylogenetic information and ease of identification of the taxon. The results favour retaining of Roella, Prismatocarpus and Merciera as separate genera. A synopsis of these three is provided

Metallic Ferroelectricity and Superconductivity in the Transition Metal Oxide Pyrochlore Cd\u3csub\u3e2\u3c/sub\u3eRe\u3csub\u3e2\u3c/sub\u3eO\u3csub\u3e7\u3c/sub\u3e

Single crystalline samples of transition metal oxide Cd2Re2O7, the first superconductor among pyrochlore oxides with general formula A2B2O7 and the first example of “ferroelectric metal” theoretically proposed by P.W. Anderson and E.I. Blount back in 1960s, have been grown using vapor transport and carefully characterized, regarding its chemical stoichiometry and structure. In addition to the superconductivity transition, two normal state phase transitions and the anomalous high temperature phase have been comprehensively investigated, by means of transport, thermodynamic and spectroscopy techniques. The system undergoes a subtle continuous cubic-to-tetragonal phase transition at T*~ 200 K, a weak first-order tetragonal-to-tetragonal phase transition at T’~ 120 K. Theoretical calculation indicates the primary lattice instability comes from a two-fold degenerate soften phonon mode with Eu symmetry, and the motions of the oxygen octahedron coordinating Re dominate the energetics of the 200 K transition. Consistently, structural study suggests a staggered distortion of the Re-Re bond in the Re tetrahedral network, such that finite local distortions do not produce appreciable change in lattice constant. The complex and subtle change in normal state physical properties can be explained within a new type of ionic fluctuation model with metallic “ferroelectric” nature. Although the low temperature structure is yet fully determined, the 3-fold symmetry and inversion symmetry are clearly lost upon the onset of superconductivity at Tc~1.0 K. The superconductivity is likely of BCS type-II, but exotic in its Tc-penetration depth relation (i.e., “within a Uemura band”)

Spherical and Hyperbolic Toric Topology-Based Codes On Graph Embedding for Ising MRF Models: Classical and Quantum Topology Machine Learning

The paper introduces the application of information geometry to describe the ground states of Ising models by utilizing parity-check matrices of cyclic and quasi-cyclic codes on toric and spherical topologies. The approach establishes a connection between machine learning and error-correcting coding. This proposed approach has implications for the development of new embedding methods based on trapping sets. Statistical physics and number geometry applied for optimize error-correcting codes, leading to these embedding and sparse factorization methods. The paper establishes a direct connection between DNN architecture and error-correcting coding by demonstrating how state-of-the-art architectures (ChordMixer, Mega, Mega-chunk, CDIL, ...) from the long-range arena can be equivalent to of block and convolutional LDPC codes (Cage-graph, Repeat Accumulate). QC codes correspond to certain types of chemical elements, with the carbon element being represented by the mixed automorphism Shu-Lin-Fossorier QC-LDPC code. The connections between Belief Propagation and the Permanent, Bethe-Permanent, Nishimori Temperature, and Bethe-Hessian Matrix are elaborated upon in detail. The Quantum Approximate Optimization Algorithm (QAOA) used in the Sherrington-Kirkpatrick Ising model can be seen as analogous to the back-propagation loss function landscape in training DNNs. This similarity creates a comparable problem with TS pseudo-codeword, resembling the belief propagation method. Additionally, the layer depth in QAOA correlates to the number of decoding belief propagation iterations in the Wiberg decoding tree. Overall, this work has the potential to advance multiple fields, from Information Theory, DNN architecture design (sparse and structured prior graph topology), efficient hardware design for Quantum and Classical DPU/TPU (graph, quantize and shift register architect.) to Materials Science and beyond.Comment: 71 pages, 42 Figures, 1 Table, 1 Appendix. arXiv admin note: text overlap with arXiv:2109.08184 by other author