The Periodic Response of Tidal Flat Sediments to Runoff Variation of Upstream Main River: A Case Study in the Liaohe Estuary Wetland, China

(1) Background: To reveal the intrinsic relationship between the tidal flat sediments in an estuary wetland and the runoff from the upstream river. This research was conducted in the tidal flats of the Liaohe estuary wetland. (2) Methods: The 137Cs and 210Pb dating technique was used to reconstruct the time correspondence between tidal flat sediments and runoff, and the periodic response was explored between the changes in the tidal flat sediments and runoff based on the spectrum analysis method. (3) Results: The average sedimentation rate in the tidal flat was 2.24 cm·year−1 during the past 50 years. The amount of fine sediment particles deposited on the estuary tidal flat was directly related to the amount of sediments transported by the river and inversely proportional to the ability of rivers to transport fine matter. The high frequency reproduction cycle of 14–15 years in the flood season flow and 5–6 years in the annual sediment discharge of the Liaohe River correspond to the high and low frequency reproduction cycles of the median size of sediments in Liaohe estuarine wetland tidal flats. (4) Conclusions: The research clarified the hydrological constraints of the action law between Liaohe River runoff and the estuarine sediments. The periodic response between Liaohe River runoff and the sediment was established.

Diffuse-Field Equalisation of Binaural Ambisonic Rendering

Ambisonics has enjoyed a recent resurgence in popularity due to virtual reality applications. Low order Ambisonic reproduction is inherently inaccurate at high frequencies, which causes poor timbre and height localisation. Diffuse-Field Equalisation (DFE), the theory of removing direction-independent frequency response, is applied to binaural (over headphones) Ambisonic rendering to address high-frequency reproduction. DFE of Ambisonics is evaluated by comparing binaural Ambisonic rendering to direct convolution via head-related impulse responses (HRIRs) in three ways: spectral difference, predicted sagittal plane localisation and perceptual listening tests on timbre. Results show DFE successfully improves frequency reproduction of binaural Ambisonic rendering for the majority of sound source locations, as well as the limitations of the technique, and set the basis for further research in the field.

Factors affecting culling and survival during rearing and first lactation in purebred and crossbred dairy cattle

ABSTRACTFactors affecting survival to first and second calving and successful completion of a > 168-day first lactation were assessed in 3075 purebred and crossbred dairy heifer calves. Growth, disease, frequency, reproduction, calving, udder and lactation traits were examined in females of a breeding project conducted jointly at five research stations (herds) of Agriculture Canada. Losses included mortalities and non-discretionary culling. About 0·23 of potential heifers were culled or died before first calving, and 0·25 of those calving once did not calve a second time. Results from retrospective selection index and stepwise linear logistic analyses showed that predictability of culling prior to 308 days post partum was poor. With few exceptions, survival rates from birth to 82 weeks varied among herds (P < 0·001) and among lines (P < 0·05). Heterosis for the probability of completing a lactation and of survival to second calving was significant (P < 0·05) and positive (0·05 to 0·09). Heavier heifers were more likely to survive to first calving. Sire's estimated breeding values (SEBV) for milk yield and fat, protein and lactose concentration were not important in predicting survival to first calving. SEBV lactose was negatively associated with survival after first calving as predicted from data available at most preceding stages of life. An age greater than 82 weeks at last insemination was associated with a lower probability of survival to first and second calving (P < 0·001). Cows which conceived for a second gestation and subsequently aborted had a lower probability of survival to second calving than cows which did not abort (0·57 v. 0·76, P < 0·01). The only continuous traits with large effects on survival or the probability of completing a first lactation were days to last insemination (a measure of fertility) and milk yield. It was concluded that (1) there is considerable scope for improved management to increase survival in early life by prevention of calfhood diseases; (2) losses in early life do not bias sire evaluation on first lactation records; (3) improved reproductive success would greatly enhance overall survival rates; and (4) crossbreeding could have a large impact on overall herd profitability through increased survival.