An analysis of distal dominance in the regenerating limb of the axolotl

Résumé La régenération d'une patte (Ambystoma mexicanum) n'est pas empêchée par la présence d'une greffe d'une patte sur la surface d'amputation d'un membre hôte. La greffe d'une patte cependant articule avec le régénérat hôte à un niveau homologue le long de l'axe du membre.

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This work was supported by a grant (No. GB-2618) from the National Science Foundation.     

Topologically protected quantum bits using Josephson junction arrays

All physical implementations of quantum bits (or qubits, the logical elements in a putative quantum computer) must overcome conflicting requirements: the qubits should be manipulable through external signals, while remaining isolated from their environment. Proposals based on quantum optics emphasize optimal isolation, while those following the solid-state route exploit the variability and scalability of nanoscale fabrication techniques. Recently, various designs using superconducting structures have been successfully tested for quantum coherent operation, however, the ultimate goal of reaching coherent evolution over thousands of elementary operations remains a formidable task. Protecting qubits from decoherence by exploiting topological stability is a qualitatively new proposal that holds promise for long decoherence times, but its physical implementation has remained unclear. Here we show how strongly correlated systems developing an isolated twofold degenerate quantum dimer liquid ground state can be used in the construction of topologically stable qubits; we discuss their implementation using Josephson junction arrays. Although the complexity of their architecture challenges the technology base available today, such topological qubits greatly benefit from their built-in fault-tolerance.     

我国高校双语教学实践与研究

高校积极推动双语教学的开展,要在切实理解我国开展双语教学目的和意义的前提下,选择适合自己的双语教学模式、授课课程、授课方式等。同时开展双语教学必须考虑学生的英语基础,并根据学生的英语水平进行分类教学或分班教学,适当增加学时,灵活运用多样化的考试形式等,合理设置双语教学课程。     

Organization of microtubules in dendrites and axons is determined by a short hydrophobic zipper in microtubule-associated proteins MAP2 and tau

Here we report that the microtubule-associated proteins MAP2 and tau share two separable functional domains. One is the microtubule-binding site which serves to nucleate microtubule assembly; the second is a short C-terminal alpha-helical sequence which can crosslink microtubules by means of a hydrophobic zipper interaction into dense stable parallel arrays characteristic of axons or dendrites. Thus, interactions between molecules of a single type are capable of drastically reorganizing microtubules and completely suppressing their dynamic properties.     

大豆蛋白质的泡沫分离研究：Ⅱ.泡沫精馏过程的数学模型

在一连续操作的泡沫精馏塔中，详细 塔中泡沫在上升过程中的排液和聚并，对液膜和Ｐｌａｔｅａｕ边界中的液含量及蛋白质含量进行了衡算，从而建立了分离过程传质的数学模型，并用试验对模型进行了验证。结果表明：模型预测值与实验测定值基本吻合。     

The structure-antimicrobial relation of depsipeptides

Zusammenfassung Die Beziehungen zwischen Struktur und antimikrobieller Aktivität in der Reihe der Depsipeptide wurden untersucht. Cyclotetradepsipeptide sind praktisch inaktiv. Die grösste Aktivität besitzen die Cyclohexadepsipeptide mit regulärer Oxy- und Aminosäurensequenz. Eine weitere Vergrösserung des Depsipeptidringes führt zu einem Abfall der biologischen Aktivität. Cyclohexadepsipeptide mit irregulärer Oxy- und Aminosäurensequenz sind völlig inaktiv.

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Communication XXVII in the SeriesStudies in Depsipeptide Chemistry.     

The effect of antamanide and perhydroantamanide on the permeability of model and biological membranes

Zusammenfassung Untersuchungen mit Antamanid und Perhydroantamanid deuten darauf hin, dass für letzteres die Beeinflussung des Transportes von Na⁺- und K⁺-Ionen durch Membranen von Bedeutung sein kann.     

Karyotypes of the panamint kangaroo rat (Dipodomys panamintinus (Merriam))

Résumé Le rat KangourouDipodomys panamintinus a 4 sous-espèces. Le représentatif karyotype de 4 des sousespèces a 17 métacentriques et 14 chromosomes acrocentriques.Dipodomys panamintinus caudatus, géographiquement isolé des autres, a 16 métacentriques et 15 chromosomes acrocentriques. Le nombre fondamental est 96 pour les espèces.

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We wish to acknowledge the kind assistance of the following people in preparation of this paper: Mr.Dave Dunaway, Resident Naturalist, U.S. Forest Service; Mrs.Tilly Chamness, Coordinator, Natural Resource Management, Naval Weapon Center, China Lake.     

Discovery of a flank caldera and very young glacial activity at Hecates Tholus, Mars

The majority of volcanic products on Mars are thought to be mafic and effusive. Explosive eruptions of basic to ultrabasic chemistry are expected to be common, but evidence for them is rare and mostly confined to very old surface features. Here we present new image and topographic data from the High Resolution Stereo Camera that reveal previously unknown traces of an explosive eruption at 30 degrees N and 149 degrees E on the northwestern flank of the shield volcano Hecates Tholus. The eruption created a large, 10-km-diameter caldera approximately 350 million years ago. We interpret these observations to mean that large-scale explosive volcanism on Mars was not confined to the planet's early evolution. We also show that glacial deposits partly fill the caldera and an adjacent depression. Their age, derived from crater counts, is about 5 to 24 million years. Climate models predict that near-surface ice is not stable at mid-latitudes today, assuming a thermo-dynamic steady state. Therefore, the discovery of very young glacial features at Hecates Tholus suggests recent climate changes. We show that the absolute ages of these very recent glacial deposits correspond very well to a period of increased obliquity of the planet's rotational axis.