Turbulent mixing at a stable density interface : the variation of the buoyancy flux–gradient relation

Experiments conducted on mixing across a stable density interface in a turbulent Taylor–Couette flow show, for the first time, experimental evidence of an increase in mixing efficiency at large Richardson numbers. With increasing buoyancy gradient the buoyancy flux first passes a maximum, then decreases and at large values of the buoyancy gradient the flux increases again. Thus, the curve of buoyancy flux versus buoyancy gradient tends to be N-shaped (rather than simply bell shaped), a behaviour suggested by the model of Balmforth et al. (J. Fluid Mech. vol. 428, 1998, p. 349). The increase in mixing efficiency at large Richardson numbers is attributed to a scale separation of the eddies active in mixing at the interface; when the buoyancy gradient is large mean kinetic energy is injected at scales much smaller than the eddy size fixed by the gap width, thus decreasing the eddy turnover time. Observations show that there is no noticeable change in interface thickness when the mixing efficiency increases; it is the mixing mechanism that changes. The curves of buoyancy flux versus buoyancy gradient also show a large variability for identical experimental conditions. These variations occur at time scales one to two orders of magnitude larger than the eddy turnover time scale

Dynamics and morpho-sedimentary interactions in the lower mesotidal estuary of Villaviciosa (NW Spain) : A management proposal

The accumulation of sediment in the mouth of Villaviciosa estuary (NW Spain) is becoming an obstaclefor the safe navigation in this estuary. One sector of its outer inlet is characterised by a broad shoal linkedwith a longshore bar of a beach, whose erosion is causing the silting of this area. On this basis, this paperaims to describe the processes that occurred in the lower part of the estuary due to the anthropogenicactivities in the channel and inlet. For this purpose, several measurements were made in the watercolumn and in the sedimentary bottoms to characterise the processes that occur in this area. Based onthese results, a dynamic and morpho-sedimentary model was developed to examine the interactionsbetween the lower estuary and the exposed part of the confining barrier beach, which allows to establishthe evolutionary trends of sedimentary bottoms linked to the marina of El Puntal. Different managementmeasures are carried out to reduce the impact of the sediment accumulation on the navigability, such asperiodically dredging in the inlet of the estuary, and the subsequent dumping of the sediments in areasnear to the closure depth. Consequently, future retreat of narrow inlet and sandy shoal can be avoided,maintaining the sedimentary volume in the system

Morphodynamics, sedimentary and anthropogenic influences in the San Vicente de la Barquera estuary (North coast of Spain)

The estuary of San Vicente de la Barquera occupies two valleys that have incised into soft sedimentary rocks (Lower Mesozoic) and are controlled by inactive faults. These two estuary subsystems, the Escudo (main valley) and Gandarilla, share outer estuarine zones, i.e., a sandy bay and mouth complex. There is a confining barrier consisting of an aeolian dune/beach system that is currently fixed by a NE-trending jetty that has allowed system progradation over the past 50 years. Connected to the inner inlet in the sand bay is a flood-tidal delta, the most important dynamic and sedimentary unit, which exhibits a heart shape caused by the large amplitude of flows in this estuarine zone and channelizes the flows and sediments into the estuary, primarily during rising and high tides. In particular, a counterclockwise rotation due to the Coriolis effect is essential to the development of this sand structure, including the ebb and flood tide structures, primarily spill-over lobes, sand waves and megaripples.The presence of estuarine beaches into the bay is common in many Cantabrian estuaries, even culminating in small dune fields, in this case with anthropic origin.This paper explains the human occupation and port management, besides the dynamic and sedimentary distribution of a bar-barrier estuary and the changes produced in its distal part by construction of two jetties in the mouth

Morphodynamics, sedimentary and anthropogenic influences in the San Vicente de la Barquera estuary (North coast of Spain)

The estuary of San Vicente de la Barquera (Cantabria, Spain) occupies two fluvial valleys that have incised into soft sedimentary rocks (Lower Mesozoic) and are controlled by inactive faults. These two estuary subsystems, the Escudo (main valley) and Gandarilla, share outer estuarine zones, i.e., a sandy bay and an estuary-mouth complex. The complexity of the system lies in the presence of a confining barrier formed by an aeolian dune/ beach system that is currently enclosed by a jetty, which has allowed the dune progradation over the past 50 years. Furthermore, connected to the inner inlet in the sand bay there is a flood-tidal delta, the most important morphosedimentary and dynamic unit. This unit exhibits a heart shape caused by the wide range of flows in this estuarine zone and channelizes the flows and sediments into the estuary, primarily during rising and high tides. In particular, the counter-clockwise surficial rotation due to the Coriolis effect is essential to the development of sand shoals, spill-over lobes, sand waves and megaripples. The presence of estuarine beaches into the bay is common in many Cantabrian estuaries, even culminating in small dune fields, in this case due to anthropogenic influences. This paper explains the impact on the estuary of human occupation and port management, focussing on the dynamic and sedimentary distribution of a bar-barrier estuary and the changes produced in its distal part by the construction of the two jetties in the mouth

Superior Facial Expression, But Not Identity Recognition, in Mirror-Touch Synesthesia

Simulation models of expression recognition contend that to understand another's facial expressions, individuals map the perceived expression onto the same sensorimotor representations that are active during the experience of the perceived emotion. To investigate this view, the present study examines facial expression and identity recognition abilities in a rare group of participants who show facilitated sensorimotor simulation (mirror-touch synesthetes). Mirror-touch synesthetes experience touch on their own body when observing touch to another person. These experiences have been linked to heightened sensorimotor simulation in the shared-touch network (brain regions active during the passive observation and experience of touch). Mirror-touch synesthetes outperformed nonsynesthetic participants on measures of facial expression recognition, but not on control measures of face memory or facial identity perception. These findings imply a role for sensorimotor simulation processes in the recognition of facial affect, but not facial identity

Hydrodynamic controls of morpho-sedimentary evolution in a rock-bounded mesotidal estuary. Tina Menor (N Spain)

The Tina Menor estuary is a highly confined incised valley with advanced sedimentary infilling. The outstanding feature of this estuary is its longitudinal zonation, which forms four segments from the outer to the inner limit: Mouth complex, Bay, Tidal flats and Upper channel. The innermost part of the Bay and the Tidal Flats (semi-reclaimed areas) are broader estuarine zones, whereas the Mouth Complex and outermost Bay are confined by narrow rocky outcrops. This paper explains the dynamics and sedimentary distribution of a highly confined and singular estuary, detailing the fluvial-tidal controls on the variations in water mixing (QF/QT). This estuary is largely of salt wedge type and the dynamics are characterised by recording currents (speed and direction) in the water column during a tidal cycle in a spring tide; this process consists of the tidal waves propagation and their dissipation upstream hypo-synchronously and the mixing of fresh and saline waters. The morphology, dynamics and sedimentary distributions have been integrated to develop a conceptual model that demonstrates the circulation within the estuary. The sinuous geometry of the estuarine valley and the Coriolis Effect detected, play a fundamental role in determining the morphology and sedimentary distribution. Consequently, this study provides an adequate overview of this type of confined mesotidal estuary, quite common in the eastern Atlantic coast.The mrophology, dynamics and sedimentary distributions have been integrated to develop a conceptual model that demonstrates the circulation within the estuary. The sinous geometry of the estuarine valley and the Coriolis effect detected, play  a fundamental role in determining the morphology and sedimentary distribution. Consequently, this study provides an adequate overview of this type of confined mesotidal estuary, quite common in the eastern Atlantic coast.El estuario de Tina Menor es un valle encajado altamente confinado y sedimentariamente en un avanzado estado de colmatación. Se caracteriza por su zonación longitudinal en cuatro segmentos bien diferenciados desde su sector más externo hasta el límite interior: Complejo de Desembocadura, Bahía, Llanuras Mareales y Canal Superior. El interior de la Bahía y las Llanuras Mareales de carácter fangoso (zonas semi-reclamadas) son las más extensas, mientras que el Complejo de Desembocadura y la parte externa de la Bahía, están estrechamente confinadas por afloramientos rocosos. Este trabajo explica la distribución dinámica y sedimentaria de un estuario singular y altamente confinado, detallando los controles fluviales-mareales en la variación de las mezclas de agua (QF/QT). Este estuario es en gran parte del tipo de cuña salina y la dinámica fue caracterizada por las medidas de corrientes (velocidad y dirección) realizadas en la columna de agua durante un ciclo mareal en marea viva; este proceso consiste en la propagación de las ondas de marea y su disipación de aguas arriba hiposincrónicamente y la mezcla de aguas dulces y salinas. La morfología, dinámica y las distribuciones sedimentarias, se han integrado para desarrollar un modelo conceptual que demuestre la circulación dentro del estuario. La geometría sinuosa del valle estuarino y la detección del efecto de Coriolis, juegan un rol fundamental para determinar la distribución morfologica y sedimentaria. Consecuentemente, este estudio proporciona un visión adecuada de este tipo de estuarios mesomareales confinados, tan comunes en las costas atlánticas orientales

Industrias paleolíticas eolizadas en la región del Cabo de Peñas (Asturias)

[Resumen] En el borde costero de la región del Cabo Peñas ( Asturias ), se encuentran numerosos registros sedimentarios y prehist6ricos, particularmente del Paleolítico Inferior, que permiten una caracterización precisa entre la evolución litoral y los asentamientos humanos. En este trabajo, se estudian dos localizaciones prehistóricas de indudable interés: la punta de Cabo Peñas y El Otero ( Xagó ), donde vienen apareciendo útiles con signos evidentes de haber sido trabajados por el viento y que se encuentran asociados claramente al ambiente sedimentario. Se han sometido a análisis tipológicos y sedimentológicos, intentandose una aproximación cronológica.[Abstract] In the central and western coastal zone of the Cabo Peñas Asturias), there are several sedimentary and prehistoric records mainly from the Lower Palaeolithic allowing an accurate characterization between the littoral evolution and human establishment. In this work two interesting prehistoric sites are studied Cabo Peñas and El Otero ( Xagó ) where we met sorne eolized prehistoric industries associated to the sedimentary environment. Typologic and sedimentologic analysis were made and a chronology of the process was trie

The Interactive Effects of Pragmatic-Eliciting Tasks and Pragmatic Instruction

The effects of data-gathering methods on pragmatic data have been well documented, yet an inquiry into the interactive effects of assessment tasks with pragmatic instruction has received scant attention. This study investigated the interaction between two assessment tasks (e-mail and phone) and two types of pragmatic instruction (explicit and implicit). Forty-nine Spanish learners of English engaged in these two tasks as pre- and posttests. The explicit group received 12 hours of metapragmatic information on head acts and hedges in suggestions while the implicit group was the recipient of recast and input enhancement activities. The results showed that postinstructional improvement of the explicit condition was significantly more than that of the implicit condition in the phone task, although improvements of these two conditions were on par in the e-mail task. This task-induced variability might have been caused by an interaction between the feature of the two types of knowledge (i.e., monitoring capability) and an access to the knowledge bases (i.e., the role of attention to appropriateness and accuracy) in the two task

Pooled Time Series Modeling Reveals Smoking Habit Memory Pattern

Smoking is a habit that is hard to break because nicotine is highly addictive and smoking behavior is strongly linked to multiple daily activities and routines. Here, we explored the effect of gender, age, day of the week, and previous smoking on the number of cigarettes smoked on any given day. Data consisted of daily records of the number of cigarettes participants smoked over an average period of 84 days. The sample included smokers (36 men and 26 women), aged between 18 and 26 years, who smoked at least five cigarettes a day and had smoked for at least 2 years. A panel data analysis was performed by way of multilevel pooled time series modeling. Smoking on any given day was a function of the number of cigarettes smoked on the previous day, and 2, 7, 14, 21, 28, 35, 42, 49, and 56 days previously, and the day of the week. Neither gender nor age influenced this pattern, with no multilevel effects being detected, thus the behavior of all participants fitted the same smoking model. These novel findings show empirically that smoking behavior is governed by firmly established temporal dependence patterns and inform temporal parameters for the rational design of smoking cessation programs

El complejo de dunas eólicas de la Playa de Frouxeira (Meirás-Valdoviño, La Coruña)

[Resumen] Dentro del complejo dunar, situado en la parte posterior de la playa de Frouxeira, se han distinguido varios tipos de dunas : montículos aislados, remontantes, parabólicas y blow-outs y cartografiados en cuatro subzonas: dunas activas, subrecientes, remontantes y fósiles. Se establecen las características texturales de las arenas dunares y de playa, tanto granulométricas como a partir de los índices de correlación lineal entre los diferentes parámetros, además del contenido carbonatado. Finalmente, se determina la evolución sedimentaria y su relación con el resto de la cornisa cantábrica, mediante los datos prehistóricos asociados al medio de depósito[Abstract] Several coastal sand dunes are classified ( isolated mounds, climbing, parabolic and blow-outs ) and they are distributed in four areas: active, subrecent, climbing and fossil ones. Textural patterns as well granulometric parameters as lineal correlation index among them are stablished. Finally, the sedimentary evolution is determlnated by the help of the prehistoric information from the Asturian and Cantabrian region