1,474 research outputs found

    Florida's West Coast inlets: shoreline effects and recommended action

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    This report responds to the 1986 Beaches Bill which, in recognition of the potential deleterious impact on Florida's beaches of inlets modified for navigation, mandated a study of those inlets with identification of recommended action to reduce the impacts. This report addresses west Coast inlets; East Coast inlets are the subject of a companion report. There are 37 inlets along that portion of Florida's West Coast commencing from Pensacola Bay Entrance to Caxambas Pass at the south end of Marco Island. Compared to those on the East Coast, most West Coast inlets have not had the deleterious effects on the adjacent beaches, yet all modified inlets without proper management have the potential of impacting unfavorably on the adjacent shorelines. Moreover, at present there is interest in opening three West Coast entrances which either have been open in the past (Midnight Pass) or which have opened occasionally (Navarre Pass and Entrance to Phillips Lake). A review of inlets in their natural condition demonstrates the presence of a shallow broad outer bar across which the longshore transport Occurs. These shallow and shifting bar features were unsuitable for navigation which in many cases has led to the deepening of the channels and fixing with one or two jetty structures. Inlets in this modified state along with inappropriate maintenance practices have the potential of placing great ero$ional stress along the adjacent beaches. Moreover. channel dredging can reduce wave sheltering of the shoreline by ebb tidal shoals and alter the equilibrium of the affected shoreline segments. The ultimate in poor sand management practice is the placement of good quality beach sand in water depths too great for the sand to reenter the longshore system under natural forces; depths of 12 ft. or less are considered appropriate for Florida in order to maintain the sand in the system. With the interference of the nearshore sediment transport processes by inlets modified for navigation, if the adjacent beaches are to be stabilized there must be an active monitoring program with commitment to placement of dredged material of beach quality on shoreline segments of documented need. Several East Coast inlets have such transfer facilities; however. the quantities of sand transferred should be increased. Although an evolution and improvement in the technical capability to manage sand resources in the vicinity of inlets is expected, an adequate capability exists today and a concerted program should be made to commence a scheduled implementation of this capability at those entrances causing greatest erosional stress on the adjacent shorelines. A brief summary review for each of the 37 West Coast inlets is presented including: a scaled aerial photograph, brief historical information, several items related to sediment losses at each inlet and special characteristics relevant to State responsibilities. For each inlet, where appropriate, the above infor~tion is utilized to develop a recommenced action. (PDF has 101 pages.

    Florida's East Coast Inlets: shoreline effects and recommended action

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    A brief summary review for each of the 19 inlets on Florida's East Coast is presented including: a scaled aerial photograph, brief historical information, several items related to sediment losses at each inlet and special characteristics relevant to State responsibilities. For each inlet the above information is utilized to develop a recommended action, usually in the form of periodic sand transfer quantities. (PDF contains 67 pages

    Esterification Prevents Induction of the Mitochondrial Permeability Transition by N-Acetyl Perfluorooctane Sulfonamides

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    N-Alkyl perfluorooctane sulfonamides have been widely used as surfactants on fabrics and papers, fire retardants, and anticorrosion agents, among many other commercial applications. The broad use, global distribution, and environmental persistence of these compounds has generated considerable interest regarding potentially toxic effects. We have previously reported that perfluorooctanesulfonamidoacetate (FOSAA) and N-ethylperfluorooctanesulfonamidoacetate (N-EtFOSAA) induce the mitochondrial permeability transition (MPT) in vitro, resulting in cytochrome c release, inhibition of respiration, and generation of reactive oxygen species. By synthesizing the corresponding methyl esters of FOSAA and N-EtFOSAA (methyl perlfuorinated sulfonamide acetates), we tested the hypothesis that the N-acetate moiety of FOSAA and N-EtFOSAA is the functional group responsible for induction of the MPT. Swelling of freshly isolated liver mitochondria from Sprague−Dawley rats was monitored spectrophotometrically and membrane potential (ΔΨ) was measured using a tetraphenylphosphonium-selective (TPP+) electrode. In the presence of calcium, 40 μM FOSAA and 7 μM N-EtFOSAA each induced mitochondrial swelling and a biphasic depolarization of membrane potential. Mitochondrial swelling and the second-phase depolarization were inhibited by cyclosporin-A or the catalyst of K+/H+ exchange nigericin, whereas the first-phase depolarization was not affected by either. In contrast, the methyl esters of FOSAA and N-EtFOSAA exhibited no depolarizing or MPT inducing activity. Results of this investigation demonstrate that the carboxylic acid moiety of the N-acetates is the active functional group, which triggers the MPT by perfluorinated sulfonamides

    Comment on â Utility of screening questionnaire, obesity, neck circumference, and sleep polysomnography to predict sleepâ disordered breathing in children and adolescents

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/122436/1/pan12952.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/122436/2/pan12952_am.pd

    Variations in Age-Specific Homicide Death Rates: A Cohort Explanation for Changes in the Age Distribution of Homicide Deaths

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    27 pagesAn age-period-cohort characteristic model previously used to explain age-period-specific rates of homicide arrests for those 15 to 49 from 1960 to 1995 is applied to measures of age-period-specific homicide deaths. The extension of this model to the examination of homicide victimization is significant because we are able to test the utility of the model across a longer time span (1930 to 1995) and a wider range of ages (10 to 79) and disaggregated by sex and race (Whites and non-Whites). Although the results indicate that past and recent shifts in age-period-specific rates of homicide deaths are associated with specific characteristics of cohorts, there are some important differences across race and sex groupings in the effects of these characteristics. The effects of the cohort variables examined in our model are independent of age and period, often substantively large, and last throughout the life course. The results are consistent with Durkheimian explanations of lethal violence, hypotheses from victimization theory, and basic tenets of cohort theory

    Cohort Variations and Changes in Age-Specific Suicide Rates over Time: Explaining Variations in Youth Suicide

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    38 pagesDramatic changes in the age distribution of suicide in the U.S. are associated with variations in the demographic characteristics of birth cohorts. Using an age-period-cohort-characteristic model, we show that cohort characteristics theoretically linked to integration and regulation have substantively strong and statistically significant relationships with changes in age-specific suicide rates from 1930 to 1995. Members of relatively large cohorts and of cohorts with higher percentages of nonmarital births are at greater risk for suicide throughout their life spans. These results appear for the total population and for race-sex subgroups, even though the age distributions of suicide differ substantially across these demographic groups. They can account for recent sharp increases in youth suicide, as well as more moderate increases in earlier decades

    A Common Explanation for the Changing Age Distributions of Suicide and Homicide in the United States, 1930 to 2000

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    19 pagesA longstanding debate focuses on whether suicide and homicide rates walk hand in hand or whether they are reciprocally related. Much of the research on this issue investigates whether suicide or homicide predominates in certain geographic areas or whether they trend together over time. We theorize that the degree of social integration and social regulation associated with birth cohorts is negatively related to both of these forms of lethal violence.We develop a common explanation for shifts in the age distributions of homicide and suicide in the United States from 1930 to 2000. In this context, suicide rates and homicide rates walk hand in hand and their parallel movements are associated with two variables linked to social integration and regulation
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