Sediment dynamics in the lower Mekong River : transition from tidal river to estuary

Author Posting. © American Geophysical Union, 2015. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research: Oceans 120 (2015): 6363–6383, doi:10.1002/2015JC010754.A better understanding of flow and sediment dynamics in the lowermost portions of large-tropical rivers is essential to constraining estimates of worldwide sediment delivery to the ocean. Flow velocity, salinity, and suspended-sediment concentration were measured for 25 h at three cross sections in the tidal Song Hau distributary of the Mekong River, Vietnam. Two campaigns took place during comparatively high-seasonal and low-seasonal discharge, and estuarine conditions varied dramatically between them. The system transitioned from a tidal river with ephemeral presence of a salt wedge during high flow to a partially mixed estuary during low flow. The changing freshwater input, sediment sources, and estuarine characteristics resulted in seaward sediment export during high flow and landward import during low flow. The Dinh An channel of the Song Hau distributary exported sediment to the coast at a rate of about 1 t s−1 during high flow and imported sediment in a spatially varying manner at approximately 0.3 t s−1 during low flow. Scaling these values results in a yearly Mekong sediment discharge estimate about 65% smaller than a generally accepted estimate of 110 Mt yr−1, although the limited temporal and spatial nature of this study implies a relatively high degree of uncertainty for the new estimate. Fluvial advection of sediment was primarily responsible for the high-flow sediment export. Exchange-flow and tidal processes, including local resuspension, were principally responsible for the low-flow import. The resulting bed-sediment grain size was coarser and more variable during high flow and finer during low, and the residual flow patterns support the maintenance of mid-channel islands.Office of Naval Research Grant Numbers: N00014-12-1-0181 , N00014-13-1-0127 , N00014-13-1-0781, and National Defense Science and Engineering2016-03-2

Coherence masking protection for speech in children and adults

In three experiments, we tested the hypothesis that children are more obliged than adults to fuse components of speech signals and asked whether the principle of harmonicity could explain the effect or whether it is, instead, due to children’s implementing speech-based mechanisms. Coherence masking protection (CMP) was used, which involves labeling a phonetically relevant formant (the target) presented in noise, either alone or in combination with a stable spectral band (the cosignal) that provides no additional information about phonetic identity and is well outside the critical band of the target. Adults and children (8 and 5 years old) heard stimuli that were either synthetic speech or hybrids consisting of sine wave targets and synthetic cosignals. The target and cosignal either shared a common harmonic structure or did not. An adaptive procedure located listeners’ thresholds for accurate labeling. Lower thresholds when the cosignal is present indicate CMP. Younger children demonstrated CMP effects that were both larger in magnitude and less susceptible to disruptions in harmonicity than those observed for adults. The conclusion was that children are obliged to integrate spectral components of speech signals, a perceptual strategy based on their recognition of when all components come from the same generator

Статеві особливості метаболізму міокарда в динаміці розвитку експериментального гіпертиреозу

В экспериментах на половозрелых самцах и самках крыс исследовано активность перекисного окислення липидов, антиоксидантной защиты и энергообразования в динамике развития тироксиновой кардиомиопатии, которую моделировали введением L-тироксина (500 мг/кг, внутрижелудочно, ежедневно). В миокарде желудочков через 5, 10 и 15 дней с начала эксперимента определяли содержание диеновых и триеновых коньюгат (ДК, ТК), ТБК-активных продуктов (ТБК-АП), активность супероксиддисмутазы (СОД), каталазы, глутатионпероксидазы (ГП) и глутатионредуктазы (ГР), сукцинатдегидрогеназы (СДГ), цитохромоксидазы (ЦО). Установили, что гипертироксинемия визывала накопление в миокарде желудочков крыс ДК, ТК и ТБК-АП, что в самок было более существенным, чем у самцов, несмотря на большую активность ГП та ГР. Недостаточная протекторная эффективность ферментов системы глутатиона была результатом значительного угнетения активности СОД и каталазы, что свидетельствовало о существенном накоплении активных форм кислорода. Активность энергообразования в таких условиях уменьшалась, о чем свидетельствовало угнетение активности СДГ, которое было аналогичным в самцов и самок, и ЦО, что было более существенным в самок. Полученные результаты свидетельствуют о том, что развитие тироксиновой кардиомиопатии вызывает существенный метаболический дисбаланс в миокарде желудочков самок крыс, что разрешает ожидать болем интенсивные структурные нарушения.Lipid peroxidation, antioxidant protection and energy production were studied in adult male and female rats with thyroxin cardiomyopathy, which simulated by introduction of L-thyroxine (500 mg / kg, intraperitoneally, daily). In the myocardium of the ventricles after 5, 10 and 15 days from the start of the experiment determined the content of diene and triene conjugate (DC, TC), TBA-active metabolits (TBA-am), activity of superoxide dismutase (SOD), catalase, glutathione peroxidase (GP) and glutathione reductase (GR), succinate dehydrogenase (SDH), cytochrome oxidase (CO). Found that hyperthyroxinemia caused accumulation in myocardium of the ventricles DC, TC and TBA-am mostly in females despite the higher activity of GP and GR. Lack of protective effects of glutathione system enzymes resulted from significant inhibition of SOD and catalase, indicating a significant accumulation of reactive species of oxygen. Activity of the energy production in these conditions decreased. That was proved by the inhibition of SDH in myocardium both sex animals and CO mostly in females. We conclude that the development of thyroxin cardiomyopathy causes metabolic disbalance in myocardium of the ventricles mostly in female rats, which can results in more intense structural damage

Mating rituals of the Oriente Knight Anole

This is where the abstract of this record would appear. This is only demonstration data

Bald Eagles and Man

This is where the abstract of this record would appear. This is only demonstration data

Sensory theories of developmental dyslexia: three challenges for research.

Recent years have seen the publication of a range of new theories suggesting that the basis of dyslexia might be sensory dysfunction. In this Opinion article, the evidence for and against several prominent sensory theories of dyslexia is closely scrutinized. Contrary to the causal claims being made, my analysis suggests that many proposed sensory deficits might result from the effects of reduced reading experience on the dyslexic brain. I therefore suggest that longitudinal studies of sensory processing, beginning in infancy, are required to successfully identify the neural basis of developmental dyslexia. Such studies could have a powerful impact on remediation.This is the accepted manuscript. The final version is available from NPG at http://www.nature.com/nrn/journal/v16/n1/abs/nrn3836.html

Enhanced Syllable Discrimination Thresholds in Musicians

Speech processing inherently relies on the perception of specific, rapidly changing spectral and temporal acoustic features. Advanced acoustic perception is also integral to musical expertise, and accordingly several studies have demonstrated a significant relationship between musical training and superior processing of various aspects of speech. Speech and music appear to overlap in spectral and temporal features; however, it remains unclear which of these acoustic features, crucial for speech processing, are most closely associated with musical training. The present study examined the perceptual acuity of musicians to the acoustic components of speech necessary for intra-phonemic discrimination of synthetic syllables. We compared musicians and non-musicians on discrimination thresholds of three synthetic speech syllable continua that varied in their spectral and temporal discrimination demands, specifically voice onset time (VOT) and amplitude envelope cues in the temporal domain. Musicians demonstrated superior discrimination only for syllables that required resolution of temporal cues. Furthermore, performance on the temporal syllable continua positively correlated with the length and intensity of musical training. These findings support one potential mechanism by which musical training may selectively enhance speech perception, namely by reinforcing temporal acuity and/or perception of amplitude rise time, and implications for the translation of musical training to long-term linguistic abilities.Grammy FoundationWilliam F. Milton Fun

Can Reservoir Regulation Along the Yellow River Be a Sustainable Way to Save a Sinking Delta?

Today's deltas are impacted negatively by (1) accelerated subsidence (e.g., from ground fluid extraction), (2) global eustatic sea level rise, and (3) decreased sediment supply, which increasingly starves these landforms of sediment necessary to sustain their footprint. This growing vulnerability threatens many megacities that have developed due to the rich resources offered by deltas and therefore urgently calls for efforts to maintain sustainability. The Yellow River of China is classic example of such a landform under threat and which requires human intervention to maintain its resilience. Since 2002, the Yellow River Conservancy Commission has enacted an annual water and sediment regulation scheme (WSRS) by coordinated operation of three large reservoirs in the mainstream. Here we evaluate the efficiency and sustainability of this man‐made experiment on delta evolution. The impulsive delivery of muds and sands, within ~20 day intervals (averaged duration of the WSRS), did indeed move the present Yellow River delta from a destructive phase to an accretion phase. With continuous scouring, however, the downstream riverbed erosion efficiency has decreased, due to coarsening of surface bed material sediment. Concomitantly, sediment delivery has decreased, resulting in the present delta once again entering an erosive (destructive) phase, since 2014. From a perspective of delta restoration, the WSRS on the Yellow River is effective but potentially unsustainable. Restoring delta resilience necessitates an enhanced, coordinated effort, relying upon new sciences advances, rather than simply assuming channel scour will address the sediment deficit of the delta