959 resultados para Volatilità implicita, formula di Black and Scholes
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Aim: To determine the relationship between nurse leader emotional intelligence and registered nurse job satisfaction. ^ Background: Nurse leaders influence the work environments of nurses working at the bedside. Nursing leadership plays an important role in fostering work environments that attract and retain nurses. ^ Methods: A non-experimental, predictive design study conducted in 5 hospitals evaluated relationships between 31 nurse leaders and 799 registered nurses. The nurse leaders were administered the MSCEIT and MBTI. The registered nurses participated in the 2010 NDNQI RN Job Satisfaction Survey. ^ Measurements and Results: The sample population completed two online instruments, the Mayer-Salovey-Caruso Emotional Intelligence Test (MSCEIT) and the Myers Brigg Trait Inventory (MBTI). Nurse leader demographic data was collected consisting of age, sex, race, educational level, certification status and years in the profession of nursing. The relationships among characteristics of the nurse leader and staff nurses were examined using regression analysis and stepwise deletion. The results from the MBTI were obtained electronically from CPP. Inc. and the results of MSCEIT were obtained electronically from MHS, Inc. The nurse leader response rate was 46% and the NDNQI RN Job Satisfaction response rate was 62%. The sample of 31 nurse leaders were 65 percent female and 67.7% were White, 12.9% Black, and 19.4% Hispanic. The most prevalent MBTI type was ESTJ (19.35%), followed by ENFJ and ISFJ (9.68% each). The nurse leader sample was primarily extroverts (n=20), sensing (n=18), thinking (n=16) and judging (n=19). The nurse leaders' overall MSCEIT scores ranged from 69 to 111 (implying a range from those who should consider development to competent) with a mean score of 89.84 (consider improvement). The nurse leaders scored highest in the MSCEIT Facilitating subscale with scores ranging from 69 to 121 (consider development to strength) and a mean score of 95.19 (low average score). The overall mean MSCEIT mean scores for the entire sample ranged from 89.90 to 95.19 (consider emotional intelligence improvement to low average score) Overall, staff nurse participants in the NDNQI RN Job Satisfaction Survey were moderately satisfied with the nurse leaders as noted by a mean t score of 55.03 of 60 and this score was consistent with the comparison hospitals that participated in the 2010 NDNQI RN Job Satisfaction Survey (American Nurses Association, 2010). Staff nurses gave nurse leaders a mean score of 4.50 for patient assignments appropriate, and rated a mean score of 4.35 and moderately agreeing to recommend the hospital to a friend. ^ Conclusions: Future research is needed to determine if there is a relationship between nurse leader emotional intelligence ability and registered nurse job satisfaction. Additional research is also needed to determine what to measure in regards to nurse leader emotional intelligence, ability or behavior. Another issue that emerged in the examination of EI is the moderating relationship between the nurse leaders span of control and staff nurse satisfaction on the NDNQI. ^
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Much attention has been given to treating Operation Iraqi Freedom/Operation Enduring (OIF/OEF) Veterans with posttraumatic stress disorder (PTSD). However, little attention is given to those Veterans who do not meet diagnostic criteria for PTSD but who may still benefit from intervention. Research is needed to investigate the impact of how different racial/ethnic backgrounds, different levels of social support and comorbid mental health disorders impact OIF/OEF Veterans with varying levels of PTSD. The purpose of this dissertation is to examine the association of comorbid Axis I disorders, race/ethnicity, different levels of postdeployment social support and unit support on OIF/OEF Veterans with varying levels of PTSD. Data for this dissertation were from postdeployment screenings of OIF/OEF Veterans from a large Veterans Affairs hospital in southeast Texas. To examine the study hypotheses, we conducted multinomial logistic regressions of the clinician reported data. ^ The first article examined the prevalence of subthreshold and full levels of PTSD and compared Axis I and alcohol use comorbidity rates among 1,362 OIF/OEF Veterans with varying levels of PTSD. Results suggest that OIF/OEF Veterans with subthreshold PTSD experience similar levels of psychological distress as those with full PTSD and highlight the need to provide timely and appropriate mental health services to individuals who may not meet the diagnostic criteria for full PTSD. ^ These results suggest that OIF/OEF Veterans of all race/ethnicities can benefit from strong social support systems. Postdeployment social support was found to be a protective factor against the development of PTSD among White, Black and Hispanic veterans while deployment unit support was a protective factor only among Black Veterans. The second article investigated the association between postdeployment social support and unit support with varying levels of PTSD by race/ethnicity among 1,115 OIF/OEF Veterans. ^ The results of this study can help to formulate treatment and interventions for OIF/OEF Veterans with varying levels of PTSD and social support systems.^
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Black and Hispanic youth experience the largest burden of sexually transmitted infections, teen pregnancy, and childbirth (Hamilton, Martin, & Ventura, 2011). Minority youth are disporportionately more likely to sexually debut at every age and debut before the age of 13 compared to whites (Centers for Disease Control and Prevention, 2011). However, there is little known about pre-coital sexual activity or protective parental factors in early adolscent minority youth. Parental factors such as parent-child communication and parental monitoring influence adolescent sexual behaviors and pre-coital sexual behaviors in early adolescence. Three distinct methods were used in this dissertation. Study one used qualitative methods, semi-structured, in-depth, individual interviews, to explore parent-child communication in African American mother-early adolescent son dyads. Study two used quantitative methods, secondary data analysis of a cross sectional study, to conduct a moderation analysis. For study three, I conducted a systematic review of parent-based adolescent sexual health interventions. Study one found that mothers feel comfortable talking about sex with adolescents, provide a two-prong sexual health message, and want their sons to tell their when they are thinking of having sex. Study found that parental monitoring moderates the relation between parent-child communication and pre-coital sexual behaviors. Study three found that interventions use a variety of theory, methods, and strategies and that no parent-based programs target faith-based organizations, mother-son or father-daughter dyads, or parents of LGBTQ youth. Adolescent sexual health interventions should consider addressing youth-to-parent disclosure of sexual activity or intentions to debut, addressing both parent-child sexual health communication and parental monitoring, and using a theoretical framework.^
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One of the key objectives of Deep Sea Drilling Project (DSDP) Leg 75 was to shed light on the underlying causes of Cretaceous oceanic anoxia in the South Atlantic by addressing two major hypotheses: productivity productivity-driven anoxia vs. enhanced ocean stratification leading to preservation of organic matter and black shale deposition. Here we present a detailed geochemical dataset from sediments deposited during the Cenomanian/Turonian (C/T) transition and the global oceanic anoxic event 2 (OAE 2) at DSDP Site 530A, located off-shore Namibia (southeast Angola Basin, north of Walvis Ridge). To characterise the succession of alternating black and green shales at this site and to reconstruct the evolution of their paleoenvironmental setting, we have combined data derived from investigations on bulk organic matter, biomarkers and the inorganic fraction. The location of the C/T boundary itself is biostratigraphically not well constrained due to the carbonate-poor (but organic matter-rich) facies of these sediments. The bulk d13Corg record and compound-specific d13C data, in combination with published as well as new biostratigraphic data, enabled us to locate more precisely the C/T boundary at DSDP Site 530A. The compound-specific d13C record is the first of this kind reported from C/T black shales in the South Atlantic. It is employed for paleoenvironmental reconstructions and chemostratigraphic correlation to other C/T sections in order to discuss the paleoceanographic aspects and implications of the observations at DSDP Site 530A in a broader context, e.g., with regard to the potential trigger mechanisms of OAE 2, global changes in black shale deposition and climate. On a stratigraphic level, an approximation and monitoring of the syndepositional degree of oxygen depletion within the sediments/bottom waters in comparison to the upper water column is achieved by comparing normalised concentrations of redox-sensitive trace elements with the abundance of highly source specific molecular compounds. These biomarkers are derived from photoautotrophic and simultaneously anoxygenic green sulphur bacteria (Chlorobiacea) and are interpreted as paleoindicators for events of photic zone euxinia. In contrast to a number of other OAE 2 sections that are characterised by continuous black shale sequences, DSDP Site 530A represents a highly dynamic setting where newly deposited black shales were repeatedly exposed to conditions of subtle bottom water re-oxidation, presumably leading to their progressive alteration into green shales. The frequent alternation between both facies and the related anoxic to slight oxygenated conditions can be best explained by variations in vertical extent of an oxygen minimum zone in response to changes in a highly productive western continental margin setting driven by upwelling.
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Numerous marine tephra layers cored at Sites 792 and 793 in the Izu-Bonin forearc region offer additional information about the timing and spatial characteristics of arc volcanism and the evolution of island arcs. Explosive volcanism along the Izu-Bonin Arc, with maxima just before rifting of the arc at ~40 and 5-0 Ma, produced black and white tephras of variable grain sizes and chemical compositions. Most of the tephras belong chemically to low-K and low-alkali tholeiitic rock series with a few tephra of the high-K and alkalic rock series. Most of the tephras (low-K series) were derived from the Izu-Bonin Arc, although a few were produced far to the west of the Izu-Bonin Arc (e.g., from the Ryukyu Arc). Black tephras may have come from nearby sources, such as Aogashima, Sumisu, and Torishima islands. The high-K series of tephras, within the sediments younger than 3 Ma, may reflect thickening of the island-arc crust.
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Quaternary marine tephras in the Izu-Bonin Arc offer significant information about explosive volcanic activities of the arc. Visual core descriptions, petrographic examinations, and chemical and grain-size analyses were conducted on tephras of backarc, arc, and forearc origin. Tephras are black and white and occur in simple and multiple modes with mixed and nonmixed ashes of black and white glass shards. The grain size distributions of the tephras are classified into three categories: coarse, white pumiceous, and fine white and black well-sorted types. The frequency of occurrence of the white and black tephras differs within the tectonic settings of the arc. Chemically, the Quaternary tephras in this region belong to low-alkali tholeiitic series with lower K2O and TiO2 than normal ordinary arc volcanic materials. Several tephras from different sites along the forearc correlate with each other and with tephras in the Shikoku Basin site and with Aogashima volcanics. These volcanic ashes resemble those in other backarc rifting areas, such as in the Fiji, Okinawa (Ryukyu), and Mariana regions.
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Pliocene and Pleistocene sediments of the Oman margin and Owen Ridge are characterized by continuous alternation of light and dark layers of nannofossil ooze and marly nannofossil ooze and cyclic variation of wet-bulk density. Origin of the wet-bulk density and color cycles was examined at Ocean Drilling Program Site 722 on the Owen Ridge and Site 728 on the Oman margin using 3.4-m.y.-long GRAPE (gamma ray attenuation) wet-bulk density records and records of sediment color represented as changes in gray level on black-and-white core photographs. At Sites 722 and 728 sediments display a weak correlation of decreasing wet-bulk density with increasing darkness of sediment color. Wet-bulk density is inversely related to organic carbon concentration and displays little relation to calcium carbonate concentration, which varies inversely with the abundance of terrigenous sediment components. Sediment color darkens with increasing terrigenous sediment abundance (decreasing carbonate content) and with increasing organic carbon concentration. Upper Pleistocene sediments at Site 722 display a regular pattern of dark colored intervals coinciding with glacial periods, whereas at Site 728 the pattern of color variation is more irregular. There is not a consistent relationship between the dark intervals and their relative wet-bulk density in the upper Pleistocene sections at Sites 722 and 728, suggesting that dominance of organic matter or terrigenous sediment as primary coloring agents varies. Spectra of wet-bulk density and optical density time series display concentration of variance at orbital periodicities of 100, 41, 23, and 19 k.y. A strong 41-k.y. periodicity characterizes wet-bulk density and optical density variation at both sites throughout most of the past 3.4 m.y. Cyclicity at the 41-k.y. periodicity is characterized by a lack of coherence between wet-bulk density and optical density suggesting that the bulk density and color cycles reflect the mixed influence of varying abundance of terrigenous sediments and organic matter. The 23-k.y. periodicity in wet-bulk density and sediment color cycles is generally characterized by significant coherence between wet-bulk density and optical density, which reflects an inverse relationship between these parameters. Varying organic matter abundance, associated with changes in productivity or preservation, is inferred to more strongly influence changes in wet-bulk density and sediment color at this periodicity.
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Monthly measurements of pH, alkalinity and oxygen over two years (February 1998-February 2000) at the Dyfamed site in the central zone of the Ligurian-Provençal Basin of the Mediterranean made it possible to assess the vertical distributions (5-2000 m) and the seasonal variations of these properties. Alkalinity varies linearly with salinity between surface water and the Levantine Intermediate Water (marked by a maximum of temperature and salinity). In deep water, total alkalinity is also correlated linearly to salinity, but the slope of the regression line is 15% less. In surface water, the pH at 25°C varies between 7.91 and 8.06 on the total proton scale depending upon the season. The lowest values are observed in winter, the highest in spring and in summer. These variations are primarily due to biological production. The pH goes through a minimum around 150-200 m and a small maximum below the intermediate water. The total dissolved inorganic carbon content (deduced from pH and alkalinity) is variable in surface water (2205-2310 ?mol/kg) and has a maximum in intermediate water, which is related to the salinity maximum. Normalized total inorganic carbon at a constant salinity is strongly negatively correlated with pH at 25°C. The fugacity of CO2, (fCO2) varies between 320 and 430 ?atm in surface water, according to the season. Below the seasonal thermocline, the maximum fCO2 (about 410 ?atm) is located around 150-200 m. The presence of a minimum of oxygen in the intermediate water of this area has been observed for several years, but our measurements made it possible to specify the relationship between oxygen and salinity in deep water. Data from the intense vertical mixing during the winters of 1999 and 2000 were used to calculate the oxygen quantity exchanged with the atmosphere during these periods. The estimated quantity of oxygen entering the Mediterranean Sea exceeds that deduced from exchange coefficients calculated with the formula of Wanninkhof and McGillis. During the vertical mixing in the 1999 winter, fCO2 in surface water was on average below equilibrium with atmospheric fCO2, thus implying that CO2 was entering the sea. However, on this time scale, even with high exchange coefficients, the estimated CO2 uptake had no significant influence on the inorganic carbon content in the water column.
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Studies of sulfur behavior in the water column and in sediments in river and seawater mixing zone were conducted in three areas of the Black and Azov Seas. These investigations showed constancy of sulfate concentrations versus chlorinity. Sulfur isotope composition in sulfates of surface, bottom, and pore waters depended on sulfate contents and salinity. The dependence was complicated by partial sulfate depletion in pore water due to bacterial sulfate reduction and also by alteration of isotope composition. Surface sediments in mixing zones are characterized by intensive sulfate reduction, great variability of content and isotopic composition of reduced sulfur, and a low mean isotopic fractionation factor of sulfur.
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Studies combining sedimentological and biological evidence to reconstruct Holocene climate beyond the major changes, and especially seasonality, are rare in Europe, and are nearly completely absent in Germany. The present study tries to reconstruct changes of seasonality from evidence of annual algal successions within the framework of well-established pollen zonation and 14C-AMS dates from terrestrial plants. Laminated Holocene sediments in Lake Jues (10°20.70' E, 51°39.30' N, 241 m a.s.l.), located at the SW margin of the Harz Mountains, central Germany, were studied for sediment characteristics, pollen, diatoms and coccal green algae. An age model is based on 21 calibrated AMS radiocarbon dates from terrestrial plants. The sedimentary record covers the entire Holocene period. Trophic status and circulation/stagnation patterns of the lake were inferred from algal assemblages, the subannual structure of varves and the physico-chemical properties of the sediment. During the Holocene, mixing conditions alternated between di-, oligo- and meromictic depending on length and variability of spring and fall periods, and the stability of winter and summer weather. The trophic state was controlled by nutrient input, circulation patterns and the temperature-dependent rates of organic production and mineralization. Climate shifts, mainly in phase with those recorded from other European regions, are inferred from changing limnological conditions and terrestrial vegetation. Significant changes occurred at 11,600 cal. yr. BP (Preboreal warming), between 10,600 and 10,100 cal. yr. BP (Boreal cooling), and between 8,400 and 4,550 cal. yr. BP (warm and dry interval of the Atlantic). Since 4,550 cal. yr. BP the climate became gradually cooler, wetter and more oceanic. This trend was interrupted by warmer and dryer phases between 3,440 and 2,850 cal. yr. BP and, likely, between 2,500 and 2,250 cal. yr. BP.
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Black shales possessing high concentrations of organic carbon (Foresman, 1978, doi:10.2973/dsdp.proc.40.111.1978) were deposited in many parts of the proto South Atlantic Ocean during the Cretaceous period (Bolli et al., 1978, doi:10.2973/dsdp.proc.40.104.1978). The way such sediments accumulated is not fully understood, but is likely to have occurred through a combination of low oxygen availability and abundant supply of organic matter. Thin, centimetre-thick layers of black shales are commonly interbedded with thicker layers of organic carbon-deficient, green claystones, as found in strata of Aptian to Coniacian age, at Deep Sea Drilling Project (DSDP) Site 530, in the southern Angola Basin (Hay et al., 1982, doi:10.1130/0016-7606(1982)93<1038:SAAOOC>2.0.CO;2) and elsewhere. These differences in carbon content and colour reflect the conditions of deposition, and possibly variations in the supply of organic matter (Summerhayes and Masran, 1983, doi:10.2973/dsdp.proc.76.116.1983; Dean and Gardner, 1982). We have compared, using organic geochemical methods the compositions of organic matter in three pairs of closely-bedded black and green Cenomanian claystones obtained from Site 530. Kerogen analyses and distributions of biological markers show that the organic matter of the black shales is more marine and better preserved than that of the green claystones.
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The results of investigations carried out between 1975 and 1978 are summarized. Based on observed echinoid association the flintstones were assigned to the Upper Middle Turonian. The distribution of elements was determined with nuclear absorption spectrometric methods. The black and red flintstones contain similar amounts of iron but differentiate themselves in the carbon content with the carbon being present only in black flintstones. It is assumed that the red coloration of the flintstone was caused by precipitated iron (Fe2O3) during its genesis. Although the Lower Turonian red flintstones are also present in the North Sea area, only those from Helgoland are analysed In this study.
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Maximum production in hedgerow olive orchards is likely not achieved with maximum evapotranspiration over the long-term. Thus, regulated deficit irrigation (RDI) should be considered as a management option. Four irrigation treatments were evaluated during the summer when olive is most drought resistant. Control (CON) was irrigated to maintain the rootzone close to field capacity. Severe water deficit was applied by irrigating 30% CON from end of fruit drop to end July (DI-J) and from end July until beginning of oil synthesis (DI-A). Less severe water deficit was applied during July and August (DI-JA) by irrigating 50% CON. Flowering, fruiting, abscission, fruit development, fresh and dry weight of fruits, and oil production were evaluated. There were not significant differences in number of buds initiated, number of fruits per inflorescence and fruit drop. Oil production was significantly different between irrigation treatments in all experimental years. CON produced more oil and fruit with higher oil% than DI-A and DI-JA. Oil production of DI-J was not significantly reduced compared to CON and oil% was greater. DI-J was the most effective RDI strategy; with 16% less applied water relative to CON average loss in oil production of 8% was not significantly different to CON. While DI-JA saved most water (27%), oil production was reduced by 15%. Greatest loss in oil production (21%) was observed in DI-A with water saving of 22%.
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In this paper, we give two infinite families of explicit exact formulas that generalize Jacobi’s (1829) 4 and 8 squares identities to 4n2 or 4n(n + 1) squares, respectively, without using cusp forms. Our 24 squares identity leads to a different formula for Ramanujan’s tau function τ(n), when n is odd. These results arise in the setting of Jacobi elliptic functions, Jacobi continued fractions, Hankel or Turánian determinants, Fourier series, Lambert series, inclusion/exclusion, Laplace expansion formula for determinants, and Schur functions. We have also obtained many additional infinite families of identities in this same setting that are analogous to the η-function identities in appendix I of Macdonald’s work [Macdonald, I. G. (1972) Invent. Math. 15, 91–143]. A special case of our methods yields a proof of the two conjectured [Kac, V. G. and Wakimoto, M. (1994) in Progress in Mathematics, eds. Brylinski, J.-L., Brylinski, R., Guillemin, V. & Kac, V. (Birkhäuser Boston, Boston, MA), Vol. 123, pp. 415–456] identities involving representing a positive integer by sums of 4n2 or 4n(n + 1) triangular numbers, respectively. Our 16 and 24 squares identities were originally obtained via multiple basic hypergeometric series, Gustafson’s Cℓ nonterminating 6φ5 summation theorem, and Andrews’ basic hypergeometric series proof of Jacobi’s 4 and 8 squares identities. We have (elsewhere) applied symmetry and Schur function techniques to this original approach to prove the existence of similar infinite families of sums of squares identities for n2 or n(n + 1) squares, respectively. Our sums of more than 8 squares identities are not the same as the formulas of Mathews (1895), Glaisher (1907), Ramanujan (1916), Mordell (1917, 1919), Hardy (1918, 1920), Kac and Wakimoto, and many others.