1,741,604 research outputs found
B'nai B'rith. Swampscott-Marblehead Chapter No. 847 (Swampscott, Mass.) records, 1954-1958.
No full textThe Swampscott-Marblehead B’nai B’rith Chapter No. 847 is a local chapter of B’nai B’rith International, an organization founded in 1843 that advocates for the Jewish people and the State of Israel and works to combat anti-Semitism. This collection contains a program for an installation and dinner as well as the chapter’s newsletters.Published citations should take the following form: Identification of item, date (if known); Swampscott-Marblehead B'nai B'rith Chapter No. 847 Records ; I-579; box number; folder number; American Jewish Historical Society, New York, NY, and Boston, MA.Donated by the Jewish Heritage Center of the North Shore i
Biogenic sedimentation at ODP Site 138-847
No full textSite 847, located on the equator beneath the region of divergent-driven upwelling in the eastern tropical Pacific Ocean, provides a continuous record of biogenic sedimentation spanning the past 3 m.y. Sediments at the site are primarily composed of carbonate and opal microfossils, with secondary amounts of detrital material that was transported to the site by means of winds. The cyclic changes in the relative abundance of carbonate and opal during the past 1 m.y. exhibit a strong 100-k.y. variability, which generally corresponds to late Pleistocene climatic oscillations. A distinct, carbonate-poor interval is evident from the last major interglacial and has been attributed to a decrease in production rather than to dissolution. The long-term changes in CaCO3 mass accumulation rates (MARs) also are driven by production rather than dissolution. High rates near 2.8 Ma are followed by a distinct minima near 1.8 Ma. CaCO3 MARs increase to a maxima near 0.4 Ma, followed by the decrease in production that occurred during the last interglacial period. Opal accumulations exhibit distinct maxima between 1.7 and 2.0 Ma, 1.1 and 1.3 Ma, and during glacial stages 6 and 2. These increases by more than a factor of 2 in opal accumulation tentatively have been attributed to opal production.
Site 847 provides the eastern anchor of three sites studied from the central (near 140°W) to eastern (near 95°W) equatorial Pacific Ocean to evaluate spatial changes in carbonate and opal sedimentation in an area of strong divergence during the past 3 m.y. Modern Oceanographic studies show a west to east gradient in surface productivity across this region. Analysis of the carbonate sedimentation for the past 3 m.y. and the opal sedimentation for the past 1 m.y. at the three sites reveals distinct differences in the respective gradients of accumulation. The west to east gradient in carbonate accumulation is small despite the fact that the eastern site is shallower and has better carbonate preservation. However, the gradient in opal accumulation is steep and shows a four- to fivefold increase from the central to the eastern equatorial Pacific sites. Thus, the surface gradient in primary production is reflected by bulk opal accumulation, not by carbonate accumulation
(Table 2) Weight percent organic carbon from ODP Site 138-847
No full textAs the length of marine cores increases and sampling intervals decrease, the need for rapid and inexpensive means of determining sediment composition has become apparent. In this study we examine one potentially useful technique for assessing compositional changes in marine cores, diffuse reflectance spectrophotometry. We examined near-ultraviolet, visible, and near-infrared reflectance spectra from five data sets. Each data set consists of calibration samples and test samples. The calibration samples' spectra were related to a sediment component using multiple linear regression. The resulting regression or calibration equations were then evaluated using the test samples. Calibration equations were written relating spectra to several sediment components incduding carbonate (Atlantic and east Pacific Rise ODP Site 847), organic carbon content (Atlantic and east Pacific Rise), and opal content (east Pacific Rise). The correlation coefficients for the regression equations ranged from a high of 0.99 for carbonate and opal at ODP Site 847 to a low of 0.97 for Atlantic carbonate indicating that spectral variations are highly correlated to sediment composition. All of the equations include a substantial number of variables from shorter visible and longer near ultraviolet wavelengths suggesting that these wavelengths are especially important for devices designed specifically to scan marine cores. Although equations for estimating organic and carbonate content appear independent of other sediment components, the opal equation is strongly dependent on carbonate content indicating that opal concentration is correlated to carbonate content.
Tests of the calibration equations indicated that all our equations reasonably estimate the pattern of changes, either down core or in surface sediments. Where our spectral estimates have difficulty is with absolute values, frequently over or underestimating observed values by a substantial amount. Within these limitations diffuse reflectance spectrophotometry can be a useful tool for characterizing marine cores and as our understanding of the relationship between spectra and mineralogy improves so will estimates of absolute values
Webster, N W, 847
No full textThis record was harvested from a previous catalogue system and will be withdrawn in 2025. Information in this record may be superseded or incomplete. Visit this record in UMA's new catalogue at: https://archives.library.unimelb.edu.au/nodes/view/424643Surname: WEBSTER. Given Name(s) or Initials: N W. Military Service Number or Last Known Location: 847. Missing, Wounded and Prisoner of War Enquiry Card Index Number: 12392.252665
Item: [2016.0049.56904] "Webster, N W, 847
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Pleistocene stable isotope record of planktonic foraminifera of ODP Site 138-847
No full textWe present Pleistocene oxygen and carbon isotope records from two planktonic foraminifer species (Globigerinoides sacculifer and Neogloboquadrina dutertrei) from Ocean Drilling Program Site 847 (0°16'N, 95°19'W; 3334 m water depth). An average sample resolution of 4500 yr was obtained by sampling at an interval of 15 cm through a continuous 35-m section from 0 to 1.15 Ma. Our d18O-based chronology is similar to that derived independently by astronomically tuning the gamma-ray attenuation porosity evaluator (GRAPE) record (Shackleton et al., 1995), though offsets as large as ± 30 k.y. occur on occasion.
The surface waters at eastern equatorial Pacific Site 847, 380 km west of the Galapagos, are characterized by strong and constant upwelling, elevated nutrient concentrations, and high productivity. The isotopic composition of G. sacculifer (300-355 µm) reflects conditions in the thin-surface mixed layer, and the composition of N. dutertrei (355-425 µm) monitors the subsurface waters of the permanent shallow (10-40 m) thermocline. The Pleistocene d18O difference (N. dutertrei minus G. sacculifer, Dd18Od-s) averages 0.9 per mil and ranges from 0 per mil to 1.7 per mil. Neglecting species effects and shell size, the average Pleistocene d13C difference (G. sacculifer minus N. dutertrei, Dd13Cs-d) is 0.0 per mil and ranges from -0.5 per mil to 0.5 per mil. The Dd18Od-s and Dd13Cs-d records are used to infer vertical contrasts in upper ocean water temperature and nutrient concentration, though d13C may also be influenced by other factors, such as CO2 gas exchange. Variations in the isotopic differences are often synchronous with glacial/interglacial climate change. Glacial periods are characterized by smaller vertical contrasts in both temperature and nutrient concentration, and by notably greater accumulation rates of N. dutertrei and CaCO3. We attribute these responses to greater upwelling at the equatorial divergence. Superimposed on the glacial/interglacial Dd18Od-s pattern is a long-term trend possibly associated with the advection of Peru Current waters. The temporal fluctuations in the isotopic contrasts are strikingly similar to those observed at Site 851 (Ravelo and Shackleton, this volume), suggesting that the inferred changes in thermal and chemical profiles occurred over a broad region in the equatorial Pacific
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