Aspect and assertion in Mandarin Chinese

Chinese has a number of particles such as le, guo, zai and zhe that add a particular aspectual value to the verb to which they are attached. There have been many characterisations of this value in the literature. In this paper, we review several existing influential accounts of these particles, including those in Li and Thompson (1981), Smith (1991), and Mangione and Li (1993). We argue that all these characterisations are intuitively plausible, but none of them is precise.We propose that these particles serve to mark which part of the sentence''s descriptive content is asserted, and that their aspectual value is a consequence of this function. We provide a simple and precise definition of the meanings of le, guo, zai and zhe in terms of the relationship between topic time and time of situation, and show the consequences of their interaction with different verb expressions within thisnew framework of interpretation

The conduction pathway of potassium channels is water free under physiological conditions.

Ion conduction through potassium channels is a fundamental process of life. On the basis of crystallographic data, it was originally proposed that potassium ions and water molecules are transported through the selectivity filter in an alternating arrangement, suggesting a "water-mediated" knock-on mechanism. Later on, this view was challenged by results from molecular dynamics simulations that revealed a "direct" knock-on mechanism where ions are in direct contact. Using solid-state nuclear magnetic resonance techniques tailored to characterize the interaction between water molecules and the ion channel, we show here that the selectivity filter of a potassium channel is free of water under physiological conditions. Our results are fully consistent with the direct knock-on mechanism of ion conduction but contradict the previously proposed water-mediated knock-on mechanism

Properties of 3-manifolds for relativists

In canonical quantum gravity certain topological properties of 3-manifolds are of interest. This article gives an account of those properties which have so far received sufficient attention, especially those concerning the diffeomorphism groups of 3-manifolds. We give a summary of these properties and list some old and new results concerning them. The appendix contains a discussion of the group of large diffeomorphisms of the $l$-handle 3-manifold.Comment: 20 pages. Plain-TeX, no figures, 1 Table (A4 format

Structural features of condensed tannins affect in vitro ruminal methane production and fermentation characteristics

An in vitro study was conducted to investigate the effects of condensed tannins (CT) structural properties, i.e. average polymer size (or mean degree of polymerization); percentage of cis flavan-3-ols and percentage of prodelphinidins in CT extracts on methane production (CH4) and fermentation characteristics. CT were extracted from eight plants in order to obtain different CT types: black currant leaves, goat willow leaves, goat willow twigs, pine bark, red currant leaves, sainfoin plants, weeping willow catkins and white clover flowers. They were analysed for CT content and CT composition by thiolytic degradation, followed by HPLC analysis. Grass silage was used as a control substrate. Condensed tannins were added to the substrate at a concentration of 40 g/kg, with or without polyethylene glycol (+ or −PEG 6000 treatment) to inactivate tannins, and then incubated for 72 h in mixed buffered rumen fluid from three different lactating dairy cows per run. Total cumulative gas production (GP) was measured by an automated gas production system. During the incubation, 12 gas samples (10 μl) were collected from each bottle headspace at 0, 2, 4, 6, 8, 12, 24, 30, 36, 48, 56 and 72 h of incubation and analyzed for CH4. A modified Michaelis–Menten model was fitted to the CH4 concentration patterns and model estimates were used to calculate total cumulative CH4 production (GPCH4). Total cumulative gas production and GPCH4 curves were fitted using biphasic and monophasic modified Michaelis-Menten models, respectively. Addition of PEG increased GP, GPCH4, and CH4 concentration compared to the −PEG treatment. All CT types reduced GPCH4 and CH4 concentration. All CT increased the half time of GP and GPCH4. Moreover, all CT decreased the maximum rate of fermentation for GPCH4 and rate of substrate degradation. The correlation between CT structure and GPCH4 and fermentation characteristics showed that the proportion of prodelphinidins within CT had the largest effect on fermentation characteristics, followed by average 27 polymer size and percentage of cis-flavan-3-ols

Variation in the solubilization of crude protein in wheat straw by different white-rot fungi

Besides their unique ability to depolymerize cell wall components, white-rot fungi are known to assimilate nitrogenous compounds from substrates. This modification may change protein solubility and fermentation in the rumen. To investigate this, the crude protein (CP) in fungal treated wheat straw (3 fungal species, 2 strains each) was fractioned according to the Cornell Net Carbohydrate and Protein System (CNCPS) and assessed for in vitro protein fermentation using a modified gas production technique (IVGPN). Results showed that fungi increased fraction A (instantaneously soluble CP; ∼2.6 times) and B1 (rapidly degradable; ∼1.2 times); and decreased the slowly degradable fraction B3 (∼41.6%) and unavailable fraction C (∼48.3%). The IVGPN of straw treated with Ceriporiopsis subvermispora strains were not different to the control, but increased by 30.2 to 47.1% in Pleurotus eryngii and Lentinula edodes strains. The IVGPN was significantly (P <  0.01) correlated to all fractions of CP, except fraction B1 and B2 (intermediately degradable). All fungi also increased the arginine (∼56%) and lysine (∼15%) contents. This study shows the importance of assessing the protein solubilization by different fungal strains, which can uncover unique mechanisms in the cell wall depolymerization

Meloidogyne minor: een nieuw beschreven Meloidogyne-soort

De nieuwe nematode soort Meloidogyne minor veroorzaakte in 2000 wortelknobbelsymptomen bij aardappelen op een perceel in Drenthe. Deze soort blijkt ook yellow patch disease te verookzaken in Engeland en Ierland. De plantenziektekundige dienst besloten hierom in samenwerking met de diensten in Engeland een pest risk analysis (PRA) uit te voeren om te zien of quarantaineregelingen wel of niet nodig zijn. Een reportage over het onderzoek naar M. minor en de uitkomsten van de PR