The shoreline of Monterey Bay, CA, USA demarcates the landward extent of the Monterey Bay National Marine Sanctuary. Along the length of that shoreline, nine beaches were profiled 34 times between ...1983 and 1998. The resulting data set provides an understanding of processes that affect beach volume, width, and shape. Monterey Bay, which is open to high-energy waves generated in the Pacific Ocean, comprises a range of beach environments that respond in a dramatic way to major storms such as the anomalously large El Niños in 1982–83 and 1997–98. This study relates the profile characteristics of the beaches to storminess, shoreline location, and geomorphic setting. Because the large El Niños occurred at the start and end of the study, the surveys cover both periods of nearly constant beach size and periods of extreme erosion, and the data show both the extent of erosion and accretion and the nature of the transition between the two periods.
Hurricanes have played a critical role in the transgressive evolution of Louisiana's barrier islands and may account for up to 90% of shoreline retreat measured within the historic (102years) time ...frame. Since 1901, some 55 tropical storms or hurricanes have made landfall along the Louisiana coast showing the highest incidence in September. Fewest landfalls have been recorded along the eastern region of Louisiana with the incidence being double that along the southcentral and southwest regions of the State. Approximately half the total number of tropical cyclone landfalls occurred in a thirty year period between 1931 and 1960, bounded by two of the 'quietist' decades of the past one hundred years; 1921-1930 with two direct landfalls, and 1961-1970 with two landfalls. Review of intensities of storms making landfall along the U.S. mainland through 1992 shows that 11 of the 50 strongest storms have impacted Louisiana. Given that the foredune elevation along the Louisiana coast seldom exceeds 2m above sea level, the sig- nificance of overwash processes and inlet breaching becomes readily apparent. Episodic landward translation of the beach of near 100 m is typical during stronger hurricanes. Post-storm recovery of the barrier islands has been thwarted by a reduction of sediment supplied to the littoral zone over time, subsidence, rapid relative sea-level rise and anthropogenic activity. Consequently, Louisiana's barrier islands are predisposed towards chronic erosion and land loss. Although hurricanes have proven destructive along the open coast, they have resulted in considerable deposition on portions of Louisiana's marshes. Examples include over 70 cm of mixed organic and inorganic debris accumulating after Hurricane Audrey (1957) and up to 16 cm of vertical accretion after Hurricane Andrew (1992). However, ongoing work suggests that substrate compression during storm passage may significantly reduce, or nullify, the effect of storm deposition on the marshes' long-term net elevation gain. Areas of floating marsh undergo considerable damage during severe hurricanes. Predictions of future wave and storm surge accompanying severe hurricanes (category 5) indicate that significant waves heights between 1 and 2 m can be anticipated as far inland as New Orleans. A gradual landward shift of larger waves is predicted with time due to the disappearance of barrier islands and coastal retreat. Wave heights up to 4 m are predicted in Lake Ponchartrain, located immediately north of New Orleans, for a category 5 hurricane making landfall along the Isles Dernieres. On considering that modeled surge levels increase from around 4 m to 7 m along the lake's northern shore, a hurricane of this magnitude will likely cause severe destruction and evacuation problems for the City of New Orleans and surrounding metropolitan areas.
Small-scale (<5 m horizontal length) nearshore morphologic height variations were measured by combining CRAB surveys with bed elevations acquired with a 1 MHz sonic altimeter mounted on the CRAB ...during the October Phase of the DUCK94 experiment. Bedform plan views were recorded simultaneously using a 500 kHz side-scan sonar mounted on the CRAB. Waves and currents were measured at the same time. Significant temporal and spatial variations in the small-scale morphology were measured in response to changing waves and currents during the 2 weeks examined. Three cases are examined in detail: (1) mild waves and weak longshore currents resulting in wave ripples throughout the study area; (2) storm waves with strong longshore currents resulting in lunate and straight-crested mega-ripples in the trough of the barred beach; and (3) narrow-band, normally incident waves with a strong rip current resulting in a planar bed except in the throat of the rip where mega-ripples were measured. Wavenumber spectra of the bed were generally broad, indicating newly formed ripples coexisted with residual ripples from the past to form complex, multi-scaled ripple patterns.
136Xe is used as the target medium for many experiments searching for 0νββ. Despite underground operation, cosmic muons that reach the laboratory can produce spallation neutrons causing activation of ...detector materials. A potential background that is difficult to veto using muon tagging comes in the form of 137Xe created by the capture of neutrons on 136Xe. This isotope decays via beta decay with a half-life of 3.8 min and a Qβ of ∼4.16 MeV. This work proposes and explores the concept of adding a small percentage of 3He to xenon as a means to capture thermal neutrons and reduce the number of activations in the detector volume. When using this technique we find the contamination from 137Xe activation can be reduced to negligible levels in tonne and multi-tonne scale high pressure gas xenon neutrinoless double beta decay experiments running at any depth in an underground laboratory.
Over the past 100 years, the Isles Dernieres, a low-lying barrier-island chain along the central Louisiana coast, has eroded extensively. This erosion has resulted in more than 1 km of northward ...beach-face retreat and the loss of 71 percent of the total island area. The primary causes for the erosion are wind and wave attack, diminished sand supply, and relative sea- level rise. Over the short term, wind and wave attack, which produce backshore transport, beach-face erosion, and overwash deposition, are the major morpho- dynamic processes modifying the Isles Dernieres. These processes are driven by recurrent cold fronts that move through the area every few days between autumn and spring and by hurricanes that impact the area every few years during the summer and autumn. Five years of detailed topographic surveys show that a beach on the central Isles Dernieres changed significantly in both shape and sediment volume; however, the pattern of change was not the same each year. Between August 1986 and July 1988, cold- front-generated waves eroded the entire beach face and caused an average of 35 m of retreat at mean sea level and a sediment loss of about 60 m3per meter of beach width. In contrast to the relatively slow erosion caused by cold fronts, hurricane Gilbert, a category 5 hurricane that passed about 800 km south of the Isles Dernieres in September 1988, produced differential beach-face retreat of about 9 m at mean sea level and 40 m at an elevation of 0.5 m. Most of the sediment eroded from the beach face was deposited on the backshore, which resulted in only a small loss of sediment from the beach and a noteworthy decrease in beach-face slope. During the two years following hurricane Gilbert, the mean-sea-level contour remained stationary while the beach face slowly returned to its pre-Gilbert shape. Having regained that shape, the beach face began again to retreat at a rate that approximates the earlier cold-front-driven rate. That magnitude of retreat is expected to continue until another large hurricane alters the erosional pattern. The average rate of berm-crest retreat for the five-year period was 0.5 cm/day; the actual retreat, however, primarily occurred during the winter.
Solid lipid nanoparticles (SLNTM, LipopearlsTM) are nanoparticles made from solid lipids by highpressurehomogenization. Incorporation of chemically labile active ingredients intothe solid lipid ...matrix protects against chemical degradation, which is shown for vitamin E. The SLN are physically stable in aqueous dispersions and also after incorporation into a dermal cream as proven by photon correlation spectroscopy and differential scanning calorimetry. Electron microscopy and atomic force microscopy data reveal the spherical shape of the SLN and the detailed structure of the particle surface. Ultrafine particles form an adhesive film leading to an occlusive effect on the skin. The occlusion promotes the penetration of vitamin E into the skin, as shown by the stripping test. In addition to chemical stabilization of active ingredients, occlusive effects on the skin and subsequent enhanced penetration of compounds, the SLN also possess a pigment effect covering undesired colours leading to an increased aesthetic acceptance by the customer.
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Dostopno za:
DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
\Xe{136} is used as the target medium for many experiments searching for \bbnonu. Despite underground operation, cosmic muons that reach the laboratory can produce spallation neutrons causing ...activation of detector materials. A potential background that is difficult to veto using muon tagging comes in the form of \Xe{137} created by the capture of neutrons on \Xe{136}. This isotope decays via beta decay with a half-life of 3.8 minutes and a \Qb\ of \(\sim\)4.16 MeV. This work proposes and explores the concept of adding a small percentage of \He{3} to xenon as a means to capture thermal neutrons and reduce the number of activations in the detector volume. When using this technique we find the contamination from \Xe{137} activation can be reduced to negligible levels in tonne and multi-tonne scale high pressure gas xenon neutrinoless double beta decay experiments running at any depth in an underground laboratory.
In August 1992, the eye of Hurricane Andrew (a category-4 hurricane) passed within 50 km of the Isles Dernieres, a barrier-island chain adjacent to the central Louisiana coast. Lying in Hurricane ...Andrew's path was a site on the central part of Trinity Island, a low-lying island within the Isles Dernieres, where detailed topographic surveys had been conducted between August 1986 and July 1991. During that five-year period, the net impact of storms was to produce approximately 90 m of berm-crest migration to the north and a sediment loss of 81 m3/m of shoreline. Hurricane Andrew was powerful enough to strip all the sand from the beach face, leaving no berm. A survey at that site after Hurricane Andrew's passage found a sediment loss of 92 m3/m. Typically, the islands of the Isles Dernieres consist of mud with a sand veneer on the Gulf side. Based on a previously determined location of the sand-mud interface, approximately 85 m3/m of the sediment removed by Hurricane Andrew was sand; the rest was mud from the island's core. In general, sand moved northward across the muddy, low-lying posterior of the island filling the small bayous that incise the island and collecting in the southern edge of Lake Pelto, the large lagoon situated between the Isles Dernieres and mainland. Stripping the sand left the muddy core of the island exposed, and in the year following Hurricane Andrew's passage, that surface remained sandless while the upper foreshore eroded approximately 25 m.
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