Coarse sediment tracing experiment at the Promenade des Anglais (Nice, France)

2020 ◽  
Author(s):  
Duccio Bertoni ◽  
Giovanni Sarti ◽  
Giacomo Bruno ◽  
Alessandro Pozzebon ◽  
Rémi Doumasdelage ◽  
...  
Keyword(s):  
Recovery Rate ◽  
Energy State ◽  
Low Energy ◽  
Transport Rate ◽  
Coastal Protection ◽  
Time Interval ◽  
Swash Zone ◽  
Coarse Sediment ◽  
Erosion Processes ◽  
Coarse Sediments

<p><span>Coarse sediment nourishments are increasingly used as a form of coastal protection at sites where the natural shore is affected by erosion processes. Based on the extent of the erosion effects, they can be just an integration to the backshore or rather an artificial reconstruction of a beach that has been completely eroded. In both cases, the comprehension of the physical processes affecting coarse sediments would be crucial to define the transport patterns, which are not completely understood yet. In this sense, short-term tracing experiments have already proved to be a reliable method to gain a significant amount of data about sediment transport in brief timespans. The aim of this work is quantifying the transport rate of coarse tracers 4, 24 and 48 hours after the injection during a time interval characterized by very low to no wave activity. Pebbles of about 7 cm in mean diameter were sampled on the coarse-clastic beach of the Promenade des Anglais in Nice (France), which needs yearly nourishments because of a reported huge sediment loss to the offshore. Since 1969, around 600 000 m3 have been brought in order to maintain the coastline. Once the pebbles fall downslope, no natural process is able to move them back landward due to the steepness of the shoreface. Passive RFID cylinder glass tags have been inserted into the tracers, which have been measured with a caliper and weighed. A 110 m long portion of the public beach has been selected as the site of the experiment because it is confined within two consecutive boulder groynes, which reduce longshore sediment exchange with the adjacent sectors. The pebbles have been injected along 21 transects, two at the berm crest, two in the swash zone and two at the step crest. The tracers have been inserted in the surface of the beach to avoid immediate displacement due to the uprush and backwash flows. The surrounding size of the sediments was on average slightly finer than the tracers. Visual observations right after the injection allowed us to report a strong downslope movement of the swash zone pebbles. The first detection campaign after 4 hours reached just about 60% of recovery rate, which is surprisingly low compared to previous such experiments at different locations. Topographic surveys made contextually revealed the destruction of the fair-weather berm during the rising tide, which led to the burial of a large number of tracers. During the night, low-energy waves managed to wipe out the thin layer of gravel, unearthing back several marked pebbles that had not been detected before: the recovery rate was beyond 90% after 24 hours. This dataset confirms the high transport rate of coarse sediments in very short timespans and under very low energy state: such condition is responsible of moving downslope the tracers with little chance of getting them back up unless the wave motion increases significantly. Such high mobility might also imply a high wear of coarse sediments, which in turn can contribute to volume loss of the beach.</span></p>

scholarly journals Trivial low energy states for commuting Hamiltonians, and the quantum PCP conjecture

2013 ◽  
Vol 13 (5&6) ◽  
pp. 393-429
Author(s):  
Matthew Hastings
Keyword(s):  
Ground State ◽  
Coding Theory ◽  
Energy State ◽  
Ground States ◽  
Coarse Graining ◽  
Quantum Circuit ◽  
Technical Condition ◽  
Two Dimensions ◽  
Low Energy ◽  
Coarse Grained

We consider the entanglement properties of ground states of Hamiltonians which are sums of commuting projectors (we call these commuting projector Hamiltonians), in particular whether or not they have ``trivial" ground states, where a state is trivial if it is constructed by a local quantum circuit of bounded depth and range acting on a product state. It is known that Hamiltonians such as the toric code only have nontrivial ground states in two dimensions. Conversely, commuting projector Hamiltonians which are sums of two-body interactions have trivial ground states\cite{bv}. Using a coarse-graining procedure, this implies that any such Hamiltonian with bounded range interactions in one dimension has a trivial ground state. In this paper, we further explore the question of which Hamiltonians have trivial ground states. We define an ``interaction complex" for a Hamiltonian, which generalizes the notion of interaction graph and we show that if the interaction complex can be continuously mapped to a $1$-complex using a map with bounded diameter of pre-images then the Hamiltonian has a trivial ground state assuming one technical condition on the Hamiltonians holds (this condition holds for all stabilizer Hamiltonians, and we additionally prove the result for all Hamiltonians under one assumption on the $1$-complex). While this includes the cases considered by Ref.~\onlinecite{bv}, we show that it also includes a larger class of Hamiltonians whose interaction complexes cannot be coarse-grained into the case of Ref.~\onlinecite{bv} but still can be mapped continuously to a $1$-complex. One motivation for this study is an approach to the quantum PCP conjecture. We note that many commonly studied interaction complexes can be mapped to a $1$-complex after removing a small fraction of sites. For commuting projector Hamiltonians on such complexes, in order to find low energy trivial states for the original Hamiltonian, it would suffice to find trivial ground states for the Hamiltonian with those sites removed. Such trivial states can act as a classical witness to the existence of a low energy state. While this result applies for commuting Hamiltonians and does not necessarily apply to other Hamiltonians, it suggests that to prove a quantum PCP conjecture for commuting Hamiltonians, it is worth investigating interaction complexes which cannot be mapped to $1$-complexes after removing a small fraction of points. We define this more precisely below; in some sense this generalizes the notion of an expander graph. Surprisingly, such complexes do exist as will be shown elsewhere\cite{fh}, and have useful properties in quantum coding theory.

scholarly journals A Stepwise Approach to Beach Restoration at Calabaia Beach

Water ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 2677 ◽  
Author(s):  
Mario Maiolo ◽  
Riccardo Alvise Mel ◽  
Salvatore Sinopoli
Keyword(s):  
Coastal Hazards ◽  
Coastal Protection ◽  
Stepwise Approach ◽  
Strategic Resources ◽  
Erosion Processes ◽  
Blue Growth ◽  
Marine Economy ◽  
Emergency Interventions ◽  
Flooding Events ◽  
The Impact

Sea hazards are increasingly threatening worldwide coastal areas, which are among the most strategic resources of the Earth in supporting human population, economy and the environment. These hazards enhance erosion processes and flooding events, producing severe socio-economic impacts and posing a challenge to ocean engineers and stakeholders in finding the optimal strategy to protect both the coastal communities and the health of the environment. The impact of coastal hazards is actually worsened not only by an enhancing rate of relative sea level rise and storminess driven by climate changes, but also by increasing urban pressure related to the development of the sea economy. With regard to larger environmental awareness and climate change adaptation needs, the present study focuses on a stepwise approach that supports the actions for coastal protection at Calabaia Beach, which is located in the Marine Experimental Station of Capo Tirone (Cosenza, Italy). These actions first aim to protect humans and coastal assets, then to restore the environment and the local habitat, overcoming the need for the emergency interventions carried out in the last decades and pointing out that healthy ecosystems are more productive and support a sustainable marine economy (“Blue Growth”).

scholarly journals A Simplified Method for an Evaluation of the Effect of Submerged Breakwaters on Wave Damping: The Case Study of Calabaia Beach

2020 ◽  
Vol 8 (7) ◽  
pp. 510 ◽  
Author(s):  
Mario Maiolo ◽  
Riccardo Alvise Mel ◽  
Salvatore Sinopoli
Keyword(s):  
Mathematical Models ◽  
Environmental Sustainability ◽  
Computational Cost ◽  
Coastal Areas ◽  
Coastal Protection ◽  
Tyrrhenian Sea ◽  
Wave Damping ◽  
Engineering Structures ◽  
Erosion Processes ◽  
Simplified Method

Erosion processes threaten the economy, the environment and the ecosystem of coastal areas. In addition, human action can significantly affect the characteristics of the soil and the landscape of the shoreline. In this context, pursuing environmental sustainability is of paramount importance in solving environmental degradation of coastal areas worldwide, with particular reference to the design of complex engineering structures. Among all the measures conceived to protect the shoreline, environmentally friendly interventions should be supported by the stakeholders and tested by means of mathematical models, in order to evaluate their effectiveness in coastal protection through the evaluation of wave damping and bedload. This study focuses on protected nourishments, as strategic interventions aimed to counteract coastal erosion without affecting the environment. Here, we develop a simplified method to provide a preliminary assessment of the efficiency of submerged breakwaters in reducing wave energy at a relatively low computational cost, if compared to the standard 2D or full 3D mathematical models. The methodology is applied at Calabaia Beach, located in the southern Tyrrhenian Sea (Italy), in the area of the Marine Experimental Station of Capo Tirone. The results show that the simplified method is proven to be an essential tool in assisting researchers and institutions to address the effects of submerged breakwaters on nourishment protection.

scholarly journals Temporal Nonlinearity During Recovery From Sequential Inhibition by Neurons in the Cat Primary Auditory Cortex

2006 ◽  
Vol 95 (3) ◽  
pp. 1897-1907 ◽  
Author(s):  
Kyle T. Nakamoto ◽  
Jiping Zhang ◽  
Leonard M. Kitzes
Keyword(s):  
Auditory Cortex ◽  
Recovery Rate ◽  
Primary Auditory Cortex ◽  
Auditory Stimuli ◽  
Time Interval ◽  
Large Set ◽  
Strong Response ◽  
Preceding Stimulus ◽  
Sequential Inhibition ◽  
Response Area

Auditory stimuli occur most often in sequences rather than in isolation. It is therefore necessary to understand how responses to sounds occurring in sequences differ from responses to isolated sounds. Cells in primary auditory cortex (AI) respond to a large set of binaural stimuli when presented in isolation. The set of responses to such stimuli presented at one frequency comprises a level response area. A preceding binaural stimulus can reduce the size and magnitude of level response areas of AI cells. The present study focuses on the effects of the time interval between a preceding stimulus and the stimuli of a level response area in pentobarbital-anesthetized cats. After the offset of a preceding stimulus, the ability of AI cells to respond to succeeding stimuli varies dynamically in time. At short interstimulus intervals (ISI), a preceding stimulus can completely inhibit responses to succeeding stimuli. With increasing ISIs, AI cells respond first to binaural stimuli that evoke the largest responses in the control condition, i.e., not preceded by a stimulus. Recovery rate is nonlinear across the level response area; responses to these most-effective stimuli recover to 70% of control on average 187 ms before responses to other stimuli recover to 70% of their control sizes. During the tens to hundreds of milliseconds that a level response area is reduced in size and magnitude, the selectivity of AI cells is increased for stimuli that evoke the largest responses. This increased selectivity results from a temporal nonlinearity in the recovery of the level response area which protects responses to the most effective binaural stimuli. Thus in a sequence of effective stimuli, a given cell will respond selectively to only those stimuli that evoke a strong response when presented alone.

scholarly journals Highly Excited Molecular Hydrogen in Orion

1989 ◽  
Vol 120 ◽  
pp. 323-326
Author(s):  
Hans H. Hippelein ◽  
Guido Münch
Keyword(s):  
Molecular Hydrogen ◽  
Rotational Temperature ◽  
Energy State ◽  
Low Energy ◽  
Line Of Sight ◽  
Temperature Measuring ◽  
Molecule Formation ◽  
J 13 ◽  
Excitation Mechanisms

Observations of H2 lines in the IR have been mostly restricted to those with upper levels of low energy, which can be excited either collisionally in shocks or radiatively by UV starlight. In order to discriminate between the two excitation mechanisms we have measured in 11 μm range lines of the v=2-0 band arising from high rotational levels J≤;13. Their intensities, together with those of the IR lines, allow an estimate of the line of sight effective extinction and a determination of the rotational temperature measuring their joint degree of excitation. The latter parameter provides information about the energy state of the molecules at their formation and ejection from grain surfaces and thus constrains the hypothetical models for H2 molecule formation.

Control of lipid oxidation at the mitochondrial levelThis paper article is one of a selection of papers published in this Special Issue, entitled 14th International Biochemistry of Exercise Conference – Muscles as Molecular and Metabolic Machines, and has undergone the Journal’s usual peer review process.

2009 ◽  
Vol 34 (3) ◽  
pp. 382-388 ◽  
Author(s):  
Kent Sahlin
Keyword(s):  
Lipid Oxidation ◽  
Feedback Inhibition ◽  
Peer Review Process ◽  
Energy State ◽  
Tricarboxylic Acid Cycle ◽  
Low Energy ◽  
Acetyl Coa ◽  
Intensive Exercise ◽  
Transport Chain ◽  
Electron Carriers

The rate of lipid oxidation during exercise is controlled at several sites, and there is a reciprocal dependency between oxidation of lipids and carbohydrates (CHO). It is well known that the proportion of the 2 fuels oxidized is influenced by substrate availability and exercise intensity, but the mechanisms regulating fuel preferences remain unclear. During intense exercise, oxidation of long-chain fatty acids (LCFAs) decreases, and the major control is likely to be at the mitochondrial level. Potential mitochondrial sites for control of lipid oxidation include transport of LCFAs into mitochondrial matrix, β-oxidation, the tricarboxylic acid cycle, and the electron transport chain (ETC). CHO catabolism may impair lipid oxidation by interfering with the transfer of LCFAs into mitochondria and by competing for mutual cofactors (i.e., nicotinamide adenine dinucleotide and (or) coenzyme A (CoA)). The different effect of energy state on the catabolism of CHO and lipids is likely to be of major importance in explaining the shift in fuel utilization during intensive exercise. Formation of acetyl-CoA from CHO is activated by a low energy state, and will lead to accumulation of products that are inhibitory to lipid oxidation. In contrast, β-oxidation of LCFAs to acetyl-CoA is not stimulated by a low energy state. Further interaction between CHO and LCFAs may occur by substrate competition for electron carriers at ETC, due to provisions of electrons through different complexes. Feedback inhibition of β-oxidation by redox state is thought to be an important mechanism for the slowing of lipid oxidation during intensive exercise.

Revisited Syllidae of the English Channel coarse sediment communities

2017 ◽  
Vol 97 (5) ◽  
pp. 1051-1058 ◽  
Author(s):  
Jean-Philippe Pezy ◽  
Alexandrine Baffreau ◽  
Jean-Claude Dauvin
Keyword(s):  
New Species ◽  
Fine Sand ◽  
Coarse Sand ◽  
English Channel ◽  
Numerous Species ◽  
Coarse Sediment ◽  
Branchiostoma Lanceolatum ◽  
Coarse Sediments ◽  
First Time ◽  
Warm Temperate

Among the polychaetes, the Syllidae comprise numerous species whose study over many years has benefitted from valuable revisions and descriptions of new species in Europe. This abundant literature proves very useful for revisiting the taxonomy and distribution of the Syllidae in the English Channel (EC), mainly as regards existing studies on coarse sediment communities in the eastern part of the Channel. This habitat is one of the most widespread in the EC and is known as favourable for the small polychaete fauna including Syllidae. A 2-year survey (winter and summer sampling periods) covering 19 stations, associated with theBranchiostoma lanceolatumcoarse sand community offshore Dieppe-Le Tréport, led to the identification of 6537 individuals from 29 taxa including 27 species. Six fine sand stations were also sampled in which only 12 individuals were collected. Among these species, seven are new for the EC polychaete fauna and six others are observed for the first time in the eastern part of the EC. All the new species for the EC are warm temperate species previously only known south of the Bay of Biscay. The Syllidae list given in Dauvinet al. (2003) has been re-analysed and amended with our list and that of the Chausey Archipelago study (Olivieret al., 2012). To date, 91 Syllidae species have been recorded in the EC and are established mostly in coarse sediments.

Low-Energy State-Selective Charge Transfer by Multiply Charged Ions

2001 ◽  
Vol 86 (4) ◽  
pp. 616-619 ◽  
Author(s):  
G. Lubinski ◽  
Z. Juhász ◽  
R. Morgenstern ◽  
R. Hoekstra
Keyword(s):  
Charge Transfer ◽  
Energy State ◽  
Low Energy ◽  
Multiply Charged Ions ◽  
Multiply Charged ◽  
Charged Ions

scholarly journals Низкоэнергетическое состояние электронного пучка в коаксиальном диоде с однородным анодом и неоднородным профилем магнитного поля

2018 ◽  
Vol 44 (20) ◽  
pp. 102
Author(s):  
А.В. Громов ◽  
М.Б. Гойхман ◽  
Н.Ф. Ковалев ◽  
А.В. Палицин ◽  
M.I. Fuks ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Electron Beam ◽  
Energy State ◽  
Field Configuration ◽  
Low Energy ◽  
Moderate Magnetic Field ◽  
First Time ◽  
Cylindrical Anode ◽  
The Magnetic Field ◽  
Reflection Plane

AbstractThe possible formation of an extended low-energy state of electron beam in a coaxial diode with homogeneous cylindrical anode and moderate magnetic field with inhomogeneous profile is demonstrated for the first time. It is established that, depending on the magnetic field configuration, virtual cathodes (VCs) of two types can be formed: (i) a stationary VC with a localized reflection plane and (ii) a moving VC with a two-stream low-energy state of the electron beam.

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