Experimental and numerical investigation of water-surface characteristics at crossing connected non-orthogonally to four flat channels

Most studies on the flood flow characteristics at a crossing focus on channels connected orthogonally or at right angle, but studies on non-orthogonally connected channels remain limited. In this study, hydraulic-model experiments and numerical simulations are performed to analyze the characteristics of the water-surface variation in and around a crossing connected non-orthogonally to four flat channels. Comparison of the measured and simulated water depth distributions in and around the crossing indicates that the results are in relatively good agreement. In the experiment where the angle between two upstream channels is 45°, the water flow pattern in and around the crossing corresponds approximately to Type I proposed by Mignot et al. (2008). However, it was found that there is no any flow type to correspond to the water flow pattern measured in the case of the angle of 135°. For analyzing the variation of the water depth in and around the crossing with inflow, numerical simulation is performed by setting the inflow ratio of the two inlet channels to one, three, and six, respectively.

Testing the influence of crushing-surface variation on seed cracking performance between beak morphs of the African seedcracker Pyrenestes ostrinus

Extreme phenotypic polymorphism is an oft-cited example of evolutionary theory in practise. Although these morphological variations are assumed to be adaptive, few studies have biomechanically tested such hypotheses. Pyrenestes ostrinus (the African seedcracker finch) shows an intraspecific polymorphism in beak size and shape that is entirely diet driven and allelically determined. Three distinct morphs feed upon soft sedge seeds during times of abundance, but switch to specializing on three different species of sedge seeds that differ significantly in hardness during lean times. Here we test the hypothesis that beak morphology is directly related to consuming seeds of different hardness. We used a novel experimental analysis to test how beak morphology affects the efficiency of cracking sedge seeds of variable hardness. We found that neither mandibular ramus width nor crushing surface morphology had significant effects on the ability to crack different seed types. It is likely that feeding performance is correlated with other aspects of beak size and shape such as beak depth and strength, muscle force, or gape. Our results highlight how even seemingly straightforward examples of adaptive selection in nature can be complex in practice.

What’s the temperature in tropical caves?

Hourly temperature was measured for approximately one year at 17 stations in three caves in Quintana Roo, Mexico. Thirteen of these stations were in the extensive twilight zones of all three caves. All seventeen stations showed seasonality in temperature with a 3°C drop during the Nortes season. Two of the caves, Muévelo Sabrosito and Muévelo Rico, showed greater variability during the winter months while in Río Secreto (Tuch) variability was greatest during the rainy season. Río Secreto is less open to the surface than the other two. All sites also showed a daily temperature cycle, although it was very faint in some Río Secreto (Tuch) sites. While temperature variability is diminished relative to surface variation, its temporal pattern is worthy of further study.

Insertion and deletion in Northern English (ng): Interacting innovations in the life cycle of phonological processes

In north-western varieties of British English the historical process of ng-coalescence that simplified nasal + stop clusters in words like wrong and singer never ran to completion, with surface variation between [ŋ] and [ŋɡ] remaining to this day. This paper presents an empirical study of this synchronic variation, specifically to test predictions made by the life cycle of phonological processes; a diachronic account of /ɡ/-deletion has been proposed under this framework, but crucially the life cycle makes hitherto-untested predictions regarding the synchronic behaviour of (ng) in north-west England. Data from 30 sociolinguistic interviews indicate that these predictions are largely met: internal constraints on the variable are almost entirely accounted for by assuming cyclic application of /ɡ/-deletion across a stratified phonology. There is also evidence of apparent time change in the pre-pausal environment, which is becoming increasingly [ɡ]-favouring contrary to the life cycle’s predictions. It is argued that this reflects a separate innovation in the life cycle of (ng), with synchronic variation reflecting two processes: (i) the original deletion, overlaid with (ii) a prosodically-conditioned insertion process. These results have implications for theories of language change and the architecture of grammar and add to a growing body of evidence suggesting that the effect of pause on probabilistic phenomena can be synchronically variable and diachronically unstable.

What’s the Temperature in Tropical Caves?

Hourly temperature was measured for approximately one year at 17 stations in three caves in Quintana Roo, Mexico. Thirteen of these stations were in the extensive twilight zones of all three caves. All seventeen stations showed seasonality in temperature with a 3 °C drop during the Nortes season. Two of the caves, Muévelo Sabrosito and Muévelo Rico, showed greater variability during the winter months while in Rio Secreto variability was greatest during the rainy season. Río Secreto is less open to the surface than the other two. All sites also showed a daily temperature cycle, although it was very faint in some Rio Secreto sites. While temperature variability is diminished relative to surface variation, its temporal pattern is worthy of further study.