Hyperalgesic agents increase a tetrodotoxin-resistant Na+ current in nociceptors.

Sensitization of primary afferent neurons underlies much of the pain and tenderness associated with tissue injury and inflammation. The increase in excitability is caused by chemical agents released at the site of injury. Because recent studies suggest that an increase in voltage-gated Na+ currents may underlie increases in neuronal excitability associated with injury, we have tested the hypothesis that a tetrodotoxin-resistant voltage-gated Na+ current (TTX-R INa), selectively expressed in a subpopulation of sensory neurons with properties of nociceptors, is a target for hyperalgesic agents. Our results indicate that three agents that produce tenderness or hyperalgesia in vivo, prostaglandin E2, adenosine, and serotonin, modulate TTX-R INa. These agents increase the magnitude of the current, shift its conductance-voltage relationship in a hyperpolarized direction, and increase its rate of activation and inactivation. In contrast, thromboxane B2, a cyclooxygenase product that does not produce hyperalgesia, did not affect TTX-R INa. These results suggest that modulation of TTX-R INa is a mechanism for sensitization of mammalian nociceptors.

Citrate modulates the regulation by Zn2+ of N-methyl-D-aspartate receptor-mediated channel current and neurotransmitter release.

The effect of the two metal-ion chelators EDTA and citrate on the action of N-methyl-D-aspartate (NMDA) receptors was investigated by use of cultured mouse cerebellar granule neurons and Xenopus oocytes, respectively, to monitor either NMDA-evoked transmitter release or membrane currents. Transmitter release from the glutamatergic neurons was determined by superfusion of the cells after preloading with the glutamate analogue D-[3H]aspartate. The oocytes were injected with mRNA isolated from mouse cerebellum and, after incubation to allow translation to occur, currents mediated by NMDA were recorded electrophysiologically by voltage clamp at a holding potential of -80 mV. It was found that citrate as well as EDTA could attenuate the inhibitory action of Zn2+ on NMDA receptor-mediated transmitter release from the neurons and membrane currents in the oocytes. These effects were specifically related to the NMDA receptor, since the NMDA receptor antagonist MK-801 abolished the action and no effects of Zn2+ and its chelators were observed when kainate was used to selectively activate non-NMDA receptors. Since it was additionally demonstrated that citrate (and EDTA) preferentially chelated Zn2+ rather than Ca2+, the present findings strongly suggest that endogenous citrate released specifically from astrocytes into the extracellular space in the brain may function as a modulator of NMDA receptor activity. This is yet another example of astrocytic influence on neuronal activity.

Reutilização de baterias automotivas como fonte alternativa de energia.

Atualmente um dos principais objetivos na área de pesquisa tecnológica é o desenvolvimento de soluções em favor do Meio Ambiente. Este trabalho tem por objetivo demonstrar a reutilização e consequentemente o aumento da vida útil de uma bateria Chumbo-Ácido, comumente instaladas em veículos automóveis, bem como beneficiar locais e usuários remotos onde o investimento na instalação de linhas de transmissão se torna inviável geográfica e economicamente, utilizando a luz solar como fonte de energia. No entanto a parte mais suscetível a falhas são as próprias baterias, justamente pela vida útil delas serem pequenas (em torno de 3 anos para a bateria automotiva) em comparação com o restante do sistema. Considerando uma unidade que já foi usada anteriormente, a possibilidade de falhas é ainda maior. A fim de diagnosticar e evitar que uma simples bateria possa prejudicar o funcionamento do sistema como um todo, o projeto considera a geração de energia elétrica por células fotovoltaicas e também contempla um sistema microcontrolado para leitura de dados utilizando o microcontrolador ATmega/Arduino, leitura de corrente por sensores de efeito hall da Allegro Systems, relés nas baterias para abertura e fechamento delas no circuito e um sistema de alerta para o usuário final de qual bateria está em falha e que precisa ser reparada e/ou trocada. Esse projeto foi montado na Ilha dos Arvoredos SP, distante da costa continental em aproximadamente 2,0km. Foram instaladas células solares e um banco de baterias, a fim de estudar o comportamento das baterias. O programa pôde diagnosticar e isolar uma das baterias que estava apresentando defeito, a fim de se evitar que a mesma viesse a prejudicar o sistema como um todo. Por conta da dificuldade de locomoção imposta pela geografia, foi escolhido o cartão SD para o armazenamento dos dados obtidos pelo Arduino. Posteriormente os dados foram compilados e analisados. A partir dos resultados apresentados podemos concluir que é possível usar baterias novas e baterias usadas em um mesmo sistema, de tal forma que se alguma das baterias apresentar uma falha o sistema por si só isolará a unidade.

Estudo da intensificação da coalescência de emulsões de água em óleo com a aplicação de onda estacionária de ultrassom.

Considerando que o petróleo quando extraído dos poços em águas profundas chega a ter teor de água superior a 50% e que antes de ser enviado à refinaria deve ter uma quantidade de água inferior a 1%, torna-se necessário o uso de técnicas de redução da quantidade de água. Durante a extração do petróleo formam-se emulsões de água em óleo que são muito estáveis devido a um filme interfacial contendo asfaltenos e/ou resinas ao redor das gotas de água. Nesse trabalho é apresentada a utilização de ondas estacionárias de ultrassom para realizar a quebra dessas emulsões. Quando gotículas de água com dimensões da ordem de 10m, muito menores que o comprimento de onda, são submetidas a um campo acústico estacionário em óleo, a força de radiação acústica empurra as gotículas para os nós de pressão da onda. Uma célula de coalescência com frequência central ao redor de 1 MHz, constituída por quatro camadas sendo uma piezelétrica, uma de acoplamento sólido, uma com o líquido e outra refletora, foi modelada empregando o método da matriz de transferência, que permite calcular a impedância elétrica em função da frequência. Para minimizar o efeito do gradiente de temperatura entre a entrada e a saída da cavidade da célula, quando está em operação, foram utilizados dois transdutores piezelétricos posicionados transversalmente ao fluxo que são excitados e controlados independentemente. Foi implementado um controlador digital para ajustar a frequência e a potência de cada transdutor. O controlador tem como entrada o módulo e a fase da corrente elétrica no transdutor e como saída a amplitude da tensão elétrica e a frequência. Para as células desenvolvidas, o algoritmo de controle segue um determinado pico de ressonância no interior da cavidade da célula no intervalo de frequência de 1,09 a 1,15 MHz. A separação acústica de emulsões de água em óleo foi realizada em uma planta de laboratório de processamento de petróleo no CENPES/PETROBRAS. Foram testados a variação da quantidade de desemulsificante, o teor inicial de água na emulsão e a influência da vazão do sistema, com uma potência de 80 W. O teor final de água na emulsão mostrou que a aplicação de ultrassom aumentou a coalescência de água da emulsão, em todas as condições testadas, quando comparada a um teste sem aplicação de ultrassom. Identificou-se o tempo de residência no interior da célula de separação como um fator importante no processo de coalescência de emulsões de água e óleo. O uso de desemulsificante químico é necessário para realizar a separação, porém, em quantidades elevadas implicaria no uso de processos adicionais antes do repasse final do petróleo à refinaria. Os teores iniciais de água na emulsão de 30 e 50% indicam que o uso da onda estacionária na coalescência de emulsões não tem limitação quanto a esse parâmetro. De acordo com os resultados obtidos em laboratório, essa técnica seria indicada como uma alternativa para integrar um sistema de processamento primário em conjunto com um separador eletrostático.

Galvanic Corrosion of High-Temperature Low-Sag (HTLS) High Voltage Conductors: New Materials - New Challenges

High-Temperature Low-Sag (HTLS) high voltage overhead conductors offer higher operating temperatures, reduced resistance and less sag than conventional designs. With up to twice the current capacity for the same diameter conductor, they may help ease the power shortage in the constantly increasing electricity demand, but there might be some concerns about their corrosion resistance. These new conductors use materials relatively new to the power industry, such as advanced carbon fiber polymer matrix composites and unique metal matrix composites/nano-composites predominantly used in aerospace industries. This study has made an initial assessment of potential galvanic corrosion problems in three very different HTLS designs: ACCC (Aluminum Conductor Composite Core), ACCR (Aluminum Conductor Composite Reinforced) and ACSS (Aluminum Conductor Steel Supported). In particular the ACCC design was evaluated for its resistance to corrosion and compared to the other designs. The study concludes that all three designs can develop galvanic corrosion under certain circumstances. While the results are not sufficient to make service life predictions of any of the tested conductors, they point out the necessity of thorough corrosion testing of all new conductor designs.

Caracterização elétrica de túnel-FET em estrutura de nanofio com fontes de SiGe e Ge em função da temperatura.

Este trabalho teve como objetivo estudar os transistores de tunelamento por efeito de campo em estruturas de nanofio (NW-TFET), sendo realizado através de analises com base em explicações teóricas, simulações numéricas e medidas experimentais. A fim de avaliar melhorar o desempenho do NW-TFET, este trabalho utilizou dispositivos com diferentes materiais de fonte, sendo eles: Si, liga SiGe e Ge, além da variação da espessura de HfO2 no material do dielétrico de porta. Com o auxílio de simulações numéricas foram obtidos os diagramas de bandas de energia dos dispositivos NW-TFET com fonte de Si0,73Ge0,27 e foi analisada a influência de cada um dos mecanismos de transporte de portadores para diversas condições de polarização, sendo observado a predominância da influência da recombinação e geração Shockley-Read-Hall (SRH) na corrente de desligamento, do tunelamento induzido por armadilhas (TAT) para baixos valores de tensões de porta (0,5V > VGS > 1,5V) e do tunelamento direto de banda para banda (BTBT) para maiores valores tensões de porta (VGS > 1,5V). A predominância de cada um desses mecanismos de transporte foi posteriormente comprovada com a utilização do método de Arrhenius, sendo este método adotado em todas as análises do trabalho. O comportamento relativamente constante da corrente dos NW-TFETs com a temperatura na região de BTBT tem chamado a atenção e por isso foi realizado o estudo dos parâmetros analógicos em função da temperatura. Este estudo foi realizado comparando a influência dos diferentes materiais de fonte. O uso de Ge na fonte, permitiu a melhora na corrente de tunelamento, devido à sua menor banda proibida, aumentando a corrente de funcionamento (ION) e a transcondutância do dispositivo. Porém, devido à forte dependência de BTBT com o campo elétrico, o uso de Ge na fonte resulta em uma maior degradação da condutância de saída. Entretanto, a redução da espessura de HfO2 no dielétrico de porta resultou no melhor acoplamento eletrostático, também aumentando a corrente de tunelamento, fazendo com que o dispositivo com fonte Ge e menor HfO2 apresentasse melhores resultados analógicos quando comparado ao puramente de Si. O uso de diferentes materiais durante o processo de fabricação induz ao aumento de defeitos nas interfaces do dispositivo. Ao longo deste trabalho foi realizado o estudo da influência da densidade de armadilhas de interface na corrente do dispositivo, demonstrando uma relação direta com o TAT e a formação de uma região de platô nas curvas de IDS x VGS, além de uma forte dependência com a temperatura, aumentando a degradação da corrente para temperaturas mais altas. Além disso, o uso de Ge introduziu maior número de impurezas no óxido, e através do estudo de ruído foi observado que o aumento na densidade de armadilhas no óxido resultou no aumento do ruído flicker em baixa frequência, que para o TFET, ocorre devido ao armadilhamento e desarmadilhamento de elétrons na região do óxido. E mais uma vez, o melhor acoplamento eletrostático devido a redução da espessura de HfO2, resultou na redução desse ruído tornando-se melhor quando comparado à um TFET puramente de Si. Neste trabalho foi proposto um modelo de ruído em baixa frequência para o NW-TFET baseado no modelo para MOSFET. Foram realizadas apenas algumas modificações, e assim, obtendo uma boa concordância com os resultados experimentais na região onde o BTBT é o mecanismo de condução predominante.

Spin dynamics of current-driven single magnetic adatoms and molecules

A scanning tunneling microscope can probe the inelastic spin excitations of a single magnetic atom in a surface via spin-flip assisted tunneling in which transport electrons exchange spin and energy with the atomic spin. If the inelastic transport time, defined as the average time elapsed between two inelastic spin flip events, is shorter than the atom spin-relaxation time, the scanning tunnel microscope (STM) current can drive the spin out of equilibrium. Here we model this process using rate equations and a model Hamiltonian that describes successfully spin-flip-assisted tunneling experiments, including a single Mn atom, a Mn dimer, and Fe Phthalocyanine molecules. When the STM current is not spin polarized, the nonequilibrium spin dynamics of the magnetic atom results in nonmonotonic dI/dV curves. In the case of spin-polarized STM current, the spin orientation of the magnetic atom can be controlled parallel or antiparallel to the magnetic moment of the tip. Thus, spin-polarized STM tips can be used both to probe and to control the magnetic moment of a single atom.

Cyclically-arranged, storm-controlled, prograding lithosomes in Messinian terrigenous shelves (Bajo Segura Basin, western Mediterranean)

This work focuses on a Messinian shallow-marine terrigenous unit, termed the La Virgen Formation, which forms part of the sedimentary infill of the Bajo Segura Basin (Betic margin of the western Mediterranean). This formation was deposited during a high sea level phase prior to the onset of the Messinian Salinity Crisis. Stratigraphically, it comprises a prograding stack of sandstone lithosomes alternating with marly intervals (1st-order cyclicity). These lithosomes are characterized by a homoclinal geometry that tapers distally, and interfinger with pelagic sediments rich in planktonic and benthic microfauna (Torremendo Formation). An analysis of sedimentary facies of each lithosome reveals a repetitive succession of sandy storm beds (tempestites), occasionally amalgamated, which are separated by thin marly layers (2nd-order cyclicity). Each storm bed contains internal erosional surfaces (3rd-order cyclicity) that delimit sets of laminae. Two categories of storm beds have been differentiated. The first one includes layers formed below storm wave base (SWB), characterized by traction structures associated to unidirectional flows (scoured base, planar lamination, and parting lineation). The second category consists of layers deposited above the SWB which display typical high regime oscillatory flow structures (swaley and hummocky cross lamination). In both cases, the ichnological record is characterized by an oligotypic association of Ophiomorpha nodosa, which can be interpreted as the result of allochthonous tracemakers (crustaceans) transported during storm events together with the sediment. The benthic microfauna in the marly intervals that separate the sandstone lithosomes (1st-order cyclicity) indicates that the storm ebb surges were deposited at depths ranging from those of inner shelf settings (with Elphidium spp. and Cibicides lobatulus) to those of outer shelf (with Valvulineria complanata and Uvigerina cylindrica). At the distal end of the sandstone lithosomes, the planktonic microfauna is characterized by a high content of taxa indicative of warm-oligotrophic waters (Globigerinoides obliquus and Globigerinoides bulloideus). In contrast, in the marly intervals, the microfauna is dominated by species typical of cold-eutrophic waters (Globigerina and Neogloboquadrina). This alternation of planktic foraminiferal assemblages is interpreted as being the expression of climatic cycles, in which every episode of progradation of tempestite-dominated lithosomes corresponds to maximum insolation and warm waters, whereas episodes of marly deposition correspond to minimal insolation and cold waters. The 1st-order cyclicity recorded in the La Virgen Formation, in a context of terrigenous storm-dominated shelf, corresponds to sapropel/homogeneous marl cycles formed in a pelagic basin (Torremendo Fm). These cycles in pelagic sediments are commonplace throughout the Mediterranean during the Messinian and reflect precession orbital changes: repeated periods of maximum insolation – minimum precession (sapropels) and minimal insolation – maximum precession (homogeneous marls). The fact that the example of terrigenous unit studied herein is coetaneous with the well-developed reef complexes in the Mediterranean basins points out the importance of sediment supply in the formation of large-scale sandy lithosomes. This is a crucial aspect to understanding reservoir genesis as well as lateral stratigraphic relationships with potential seal and/or source rocks.

Active edible films: Current state and future trends

Active edible films represent one of the current and future trends in the development of new polymers for selected applications, particularly food packaging. Some biopolymers show excellent performance as carriers for active compounds extracted from natural sources and are able to be released at a controlled rate to packaged food. In this review we aim to present, in a comprehensive way, the most recent advances and updates in this subject, where much research is currently ongoing and new studies are reported very often. This review focuses on innovative biopolymer matrices, their processing to obtain edible active films, and present and future applications.

Evidence for non-conservative current-induced forces in the breaking of Au and Pt atomic chains

This experimental work aims at probing current-induced forces at the atomic scale. Specifically it addresses predictions in recent work regarding the appearance of run-away modes as a result of a combined effect of the non-conservative wind force and a ‘Berry force’. The systems we consider here are atomic chains of Au and Pt atoms, for which we investigate the distribution of break down voltage values. We observe two distinct modes of breaking for Au atomic chains. The breaking at high voltage appears to behave as expected for regular break down by thermal excitation due to Joule heating. However, there is a low-voltage breaking mode that has characteristics expected for the mechanism of current-induced forces. Although a full comparison would require more detailed information on the individual atomic configurations, the systems we consider are very similar to those considered in recent model calculations and the comparison between experiment and theory is very encouraging for the interpretation we propose.

Controlled Complete Suppression of Single-Atom Inelastic Spin and Orbital Cotunneling

The inelastic portion of the tunnel current through an individual magnetic atom grants unique access to read out and change the atom’s spin state, but it also provides a path for spontaneous relaxation and decoherence. Controlled closure of the inelastic channel would allow for the latter to be switched off at will, paving the way to coherent spin manipulation in single atoms. Here, we demonstrate complete closure of the inelastic channels for both spin and orbital transitions due to a controlled geometric modification of the atom’s environment, using scanning tunneling microscopy (STM). The observed suppression of the excitation signal, which occurs for Co atoms assembled into chains on a Cu2N substrate, indicates a structural transition affecting the dz2 orbital, effectively cutting off the STM tip from the spin-flip cotunneling path.

THE DESIGN OF A POWER SYSTEM FOR A WIRELESS SENSOR NETWORK FOR LONG-TERM OPERATION

Wireless sensor networks (WSNs) have shown wide applicability to many fields including monitoring of environmental, civil, and industrial settings. WSNs however are resource constrained by many competing factors that span their hardware, software, and networking. One of the central resource constrains is the charge consumption of WSN nodes. With finite energy supplies, low charge consumption is needed to ensure long lifetimes and success of WSNs. This thesis details the design of a power system to support long-term operation of WSNs. The power system’s development occurs in parallel with a custom WSN from the Queen’s MEMS Lab (QML-WSN), with the goal of supporting a 1+ year lifetime without sacrificing functionality. The final power system design utilizes a TPS62740 DC-DC converter with AA alkaline batteries to efficiently supply the nodes while providing battery monitoring functionality and an expansion slot for future development. Testing tools for measuring current draw and charge consumption were created along with analysis and processing software. Through their use charge consumption of the power system was drastically lowered and issues in QML-WSN were identified and resolved including the proper shutdown of accelerometers, and incorrect microcontroller unit (MCU) power pin connection. Controlled current profiling revealed unexpected behaviour of nodes and detailed current-voltage relationships. These relationships were utilized with a lifetime projection model to estimate a lifetime between 521-551 days, depending on the mode of operation. The power system and QML-WSN were tested over a long term trial lasting 272+ days in an industrial testbed to monitor an air compressor pump. Environmental factors were found to influence the behaviour of nodes leading to increased charge consumption, while a node in an office setting was still operating at the conclusion of the trail. This agrees with the lifetime projection and gives a strong indication that a 1+ year lifetime is achievable. Additionally, a light-weight charge consumption model was developed which allows charge consumption information of nodes in a distributed WSN to be monitored. This model was tested in a laboratory setting demonstrating +95% accuracy for high packet reception rate WSNs across varying data rates, battery supply capacities, and runtimes up to full battery depletion.

Avaliação do desempenho do sistema de mini-geração fotovoltaico na Faculdade de Ciências

Tese de mestrado integrado, Engenharia da Energia e do Ambiente, Universidade de Lisboa, Faculdade de Ciências, 2016

Sedimentology at the continental margin of the southern Weddell Sea

During four expeditions with RV "Polarstern" at the continental margin of the southern Weddell Sea, profiling and geological sampling were carried out. A detailed bathymetric map was constructed from echo-sounding data. Sub-bottom profiles, classified into nine echotypes, have been mapped and interpreted. Sedimentological analyses were carried out on 32 undisturbed box grab surface samples, as well as on sediment cores from 9 sites. Apart from the description of the sediments and the investigation of sedimentary structures on X-radiographs the following characteristics were determined: grain-size distributions; carbonate and Corg content; component distibutions in different grain-size fractions; stable oxygen and carbon isotopes in planktic and, partly, in benthic foraminifers; and physical properties. The stratigraphy is based On 14C-dating, oxygen isotope Stages and, at one site, On paleomagnetic measurements and 230Th-analyses The sediments represent the period of deposition from the last glacial maximum until recent time. They are composed predominantly of terrigenous components. The formation of the sediments was controlled by glaciological, hydrographical and gravitational processes. Variations in the sea-ice coverage influenced biogenic production. The ice sheet and icebergs were important media for sediment transport; their grounding caused compaction and erosion of glacial marine sediments on the outer continental shelf. The circulation and the physical and chemical properties of the water masses controlled the transport of fine-grained material, biogenic production and its preservation. Gravitational transport processes were the inain mode of sediment movements on the continental slope. The continental ice sheet advanced to the shelf edge and grounded On the sea-floor, presumably later than 31,000 y.B.P. This ice movement was linked with erosion of shelf sediments and a very high sediment supply to the upper continental slope from the adiacent southern shelf. The erosional surface On the shelf is documented in the sub-bottom profiles as a regular, acoustically hard reflector. Dense sea-ice coverage above the lower and middle continental slope resulted in the almost total breakdown of biogenic production. Immediately in front of the ice sheet, above the upper continental slope, a <50 km broad coastal polynya existed at least periodically. Biogenic production was much higher in this polynya than elsewhere. Intense sea-ice formation in the polynya probably led to the development of a high salinity and, consequently, dense water mass, which flowed as a stream near bottom across the continental slope into the deep sea, possibly contributing to bottom water formation. The current velocities of this water mass presumably had seasonal variations. The near-bottom flow of the dense water mass, in combination with the gravity transport processes that arose from the high rates of sediment accumulation, probably led to erosion that progressed laterally from east to West along a SW to NE-trending, 200 to 400 m high morphological step at the continental slope. During the period 14,000 to 13,000 y.B.P., during the postglacial temperature and sea-level rise, intense changes in the environmental conditions occured. Primarily, the ice masses on the outer continental shelf started to float. Intense calving processes resulted in a rapid retreat of the ice edge to the south. A consequence of this retreat was, that the source area of the ice-rafted debris changed from the adjacent southern shelf to the eastern Weddell Sea. As the ice retreated, the gravitational transport processes On the continental slope ceased. Soon after the beginning of the ice retreat, the sea-ice coverage in the whole research area decreased. Simultaneously, the formation of the high salinity dense bottom water ceased, and the sediment composition at the continental slope then became influenced by the water masses of the Weddell Gyre. The formation of very cold Ice Shelf Water (ISW) started beneath the southward retreating Filchner-Ronne Ice Shelf somewhat later than 12,000 y.B.P. The ISW streamed primarily with lower velocities than those of today across the continental slope, and was conducted along the erosional step on the slope into the deep sea. At 7,500 y.B.P., the grounding line of the ice masses had retreated > 400 km to the south. A progressive retreat by additional 200 to 300 km probably led to the development of an Open water column beneath the ice south of Berkner Island at about 4,000 y.B.P. This in turn may have led to an additional ISW, which had formed beneath the Ronne Ice Shelf, to flow towards the Filcher Ice Shelf. As a result, increased flow of ISW took place over the continental margin, possibly enabling the ISW to spill over the erosional step On the upper continental slope towards the West. Since that time, there is no longer any documentation of the ISW in the sedimentary Parameters on the lower continental slope. There, recent sediments reflect the lower water masses of the Weddell Gyre. The sea-ice coverage in early Holocene time was again so dense that biogenic production was significantly restricted.

Age determination of sediment cores from the shelf off Mauretania, West Africa

The 60 km wide shelf off Mauritania is cut by several submarine canyons. Its water-circulation is controlled by the cool Canary current and upwelling. Its Recent sediments show faunal associations remarkably related to the grain size distribution which in water depths between 40 and 80 m is strongly influenced by reworking of older coarse sand or sandstone. In this depth range a mixed biofacies originating from Pleistocene and Recent material is encountered. The present lateral faunistic and sedimentological facies change, including horizons of mixed provenance, can be recognized in vertical sequences taken by vibro-coring. This correlation combined with 14C-datations on molluscs enable the reconstruction of the history of the last glacial regression and transgression. Due to the arid climate, the emerging calcareous shelf sediments are indurated and, therefore, protected from subaerial and submarine erosion. During low sea level eolian sand migrates over the shelf, but only about 1/10 of this material remains there and is later incorporated into the sandy shelf sediments. The calculated average rate of total sedimentation during Holocene is 15 cm, and the production rate of carbonate is 5 cm/1000 years.