Saccharide Recognition by Oligo（ meta-ethynylpyridine）s in Protic Media

Previously, we have reported tris（ethynylpyridine） macrocycles as synthetic receptors for ribofuranosides, deoxyribofuranosides, and glucopyranosides. consisted of “meta”-tethered ethynylpyridine trimers. The hydrogen-bonding skeletons of the macrocycles If the ethynylpyridine unit is polymerized, the resulting oligo-and poly（rneta-ethynylpyridine） s would adopt unfolded, somewhat zigzag conformations because each pyridine nitrogen is mainly located on opposite sides of the ethynediyl bonds to cancel the dipoles. When the polymer meets with a saccharide, its pseudolinear conformation may be guided to a well-ordered helical structure in order that the nitrogen atoms of the pyridine rings inwardly interact with peripheral saccharide-OH groups in a manner similar to those of the macrocycles （Fig. 1）. Thus, the chirality of saccharides added can be transferred to the helical sense of the polymer, depending on the stereochemistry of the saccharides.     

A Systemic Development of the Interrogative Pronouns and Adverbs

This paper is about the questions used to design two large-scale organizational systems. It is thought that for these questions to be asked in a systematic manner they need to be drawn from some explicit framework. The most common framework for creating questions in the English language is the interrogative pronouns and adverts, more commonly known as Kipling’s six honest serving men. This paper re-visits these pronouns and adverbs drawing on a range of literatures to establish them into a coherent framework for designing and implementing the two large-scale projects. The paper is structured using the nodes in Checkland’s LUMAS model. It concludes with a systematically developed Interrogative Pronouns and Adverbs Framework that is worthy of further research and application.     

Trail geometry gives polarity to ant foraging networks

Pheromone trails are used by many ants to guide foragers between nest and food. But how does a forager that has become displaced from a trail know which way to go on rejoining the trail? A laden forager, for example, should walk towards the nest. Polarized trails would enable ants to choose the appropriate direction, thereby saving time and reducing predation risk. However, previous research has found no evidence that ants can detect polarity from the pheromone trail alone. Pharaoh's ants (Monomorium pharaonis) produce elaborate trail networks throughout their foraging environment. Here we show that by using information from the geometry of trail bifurcations within this network, foragers joining a trail can adaptively reorientate themselves if they initially walk in the wrong direction. The frequency of correct reorientations is maximized when the trail bifurcation angle is approximately 60 degrees, as found in natural networks. These are the first data to demonstrate how ant trails can themselves provide polarity information. They also demonstrate previously unsuspected sophistication in the organization and information content of networks in insect societies.     

Constant elevation of southern Tibet over the past 15 million years

The uplift of the Tibetan plateau, an area that is 2,000 km wide, to an altitude of about 5,000 m has been shown to modify global climate and to influence monsoon intensity. Mechanical and thermal models for homogeneous thickening of the lithosphere make specific predictions about uplift rates of the Tibetan plateau, but the precise history of the uplift of the plateau has yet to be confirmed by observations. Here we present well-preserved fossil leaf assemblages from the Namling basin, southern Tibet, dated to approximately 15 Myr ago, which allow us to reconstruct the temperatures within the basin at that time. Using a numerical general circulation model to estimate moist static energy at the location of the fossil leaves, we reconstruct the elevation of the Namling basin 15 Myr ago to be 4,689 +/- 895 m or 4,638 +/- 847 m, depending on the reference data used. This is comparable to the present-day altitude of 4,600 m. We conclude that the elevation of the southern Tibetan plateau probably has remained unchanged for the past 15 Myr.