Ocean circulation is closely linked to climate change on glacial-interglacial and shorter timescales. Extensive reorganizations in the circulation of deep and intermediate-depth waters in the ...Atlantic Ocean have been hypothesized for both the last glaciation and the subsequent Younger Dryas cold interval,, but there has been little palaeoceanographic study of the subtropical gyres. These gyres are the dominant oceanic features of wind-driven circulation, and as such they reflect changes in climate and are a significant control on nutrient cycling and, possibly, atmospheric CO2 concentrations. Here we present Cd/Ca ratios in the shells of benthic foraminifera from the Bahama banks that confirm previous suggestions, that nutrient concentrations in the North Atlantic subtropical gyre were much lower during the Last Glacial Maximum than they are today (up to 50% lower according to our data). These contrasting nutrient burdens imply much shorter residence times for waters within the thermocline of the Last Glacial Maximum. Below the glacial thermocline, nutrient concentrations were reduced owing to the presence of Glacial North Atlantic Intermediate Water. A high-resolution Cd/Ca record from an intermediate depth indicates decreased nutrient concentrations during the Younger Dryas interval as well, mirroring opposite changes at a nearby deep site,. Together, these observations suggest that the formation of deep and intermediate waters - North Atlantic Deep Water and Glacial North Atlantic Intermediate Water, respectively - wax and wane alternately on both orbital and millennial timescales.
To provide a background for ARM's activities at the North Slope of Alaska/Adjacent Arctic Ocean sites, an overview is given of our current state of knowledge of Arctic cloud and radiation properties ...and processes. The authors describe the Arctic temperature and humidity characteristics, cloud properties and processes, radiative characteristics of the atmosphere and surface, direct and indirect radiative effects of aerosols, and the modeling and satellite remote sensing of cloud and radiative characteristics. An assessment is given of the current performance of satellite remote sensing and climate modeling in the Arctic as related to cloud and radiation issues. Radiation–climate feedback processes are discussed, and estimates are made of the sign and magnitude of the individual feedback components. Future plans to address these issues are described.
Current Organ Procurement and Transplantation Network (OPTN) policy restricts certain blood type-compatible simultaneous pancreas and kidney (SPK) transplants. Using the Kidney Pancreas Simulated ...Allocation Model, we examined the effects of 5 alternative allocation sequences that allowed all clinically compatible ABO transplants.
The study cohort included kidney (KI), SPK, and pancreas alone (PA) candidates waiting for transplant for at least 1 day between January 1, 2010, and December 31, 2010 (full cohort), and kidneys and pancreata recovered for transplant during the same period. Additionally, because the waiting list has shrunk since 2010, the study population was reduced by random sampling to match the volume of the 2015 waiting list (reduced cohort).
Compared with the current allocation sequence, R4 and R5 both showed an increase in SPK transplants, a nearly corresponding decrease in KI transplants, and virtually no change in PA transplants. Life-years from transplant and median years of benefit also increased. The distribution of transplants by blood type changed, with more ABO:A, B, and AB transplants performed, and fewer ABO:O across all transplant types (KI, SPK, PA), with the relative percent changes largest for SPK.
Broadened ABO compatibility allowances primarily benefitted SPK ABO:A and AB candidates. ABO:O candidates saw potentially reduced access to transplant. The simulation results suggest that modifying the current allocation sequence to incorporate broadened ABO compatibility can result in an increase in annual SPK transplants.
Lack of standardization across sites and raters, poor interrater reliability, and possible scoring bias affecting the primary outcome measure contribute to a high failure rate in anxiety trials. ...Remote centralized raters who are blinded to protocol inclusion and exclusion criteria as well as visit number may standardize assessments across raters and eliminate scoring bias, decreasing placebo response and thereby increasing signal detection. The purpose of the primary study was to test the safety and efficacy of an anxiolytic in a double-blind, placebo-controlled (no active comparator), multicenter trial. However, there was an additional prospective objective to explore site ratings compared with remote centralized ratings in the cohort of subjects on placebo. Site raters assessed subjects 6 times over an 8-week period. The primary outcome measure was the week 8 site-rated Hamilton Anxiety Scale (HAM-A). Remote centralized raters by telephone independently rated these subjects on the HAM-A at baseline and week 6. Of the 122 subjects selected by site raters and therefore randomized, remote centralized raters would have admitted 59 (48%) and excluded 63 (52%), based on their HAM-A ratings. The mean change from baseline in HAM-A total score in the placebo group admitted to the study by site raters was 9.3, significantly higher than the 5.9 point mean change on placebo as measured by the remote centralized raters.The data are consistent with the potential for qualification bias at baseline when rated by sites. The results make a strong case for using strategies to ensure that baseline scoring is truly independent of the pressure to enroll.
An evaluation of C. pachyderma Mg/Ca using a new suite of warm water multicores from the Florida Straits shows that the slope of Mg/Ca with temperature is shallower than previously thought. Using ...secondary ionization mass spectrometry, we have documented that the distribution of magnesium within the polished walls of foraminiferal tests is Gaussian, suggesting that the Mg/Ca in these samples is not affected by the addition of a secondary high‐magnesium calcite in the walls. The Mg/Ca within a typical C. pachyderma test varies by about ±20% (1σ/μ · 100), and the variability increases slightly in tests with higher Mg/Ca. The regression of C. pachyderma Mg/Ca with temperature has a slope of 0.13 ± 0.05 mmol mol−1 per °C, indistinguishable from the slope observed in inductively coupled plasma–mass spectrometry measurements from a different subset of the same multicores, but about one half the slope of previously published calibrations. The largest differences between the calibrations comes at the warm water end of the regression, where previously published C. pachyderma Mg/Ca values from Little Bahama Bank are at least 3 mmol mol−1 higher than observed in these new cores. The reasons for this difference are not fully known but are most likely related to diagenesis at Little Bahama Bank.
SEAFLUX Curry, J. A.; Bentamy, A.; Bourassa, M. A. ...
Bulletin of the American Meteorological Society,
03/2004, Letnik:
85, Številka:
3
Journal Article
Recenzirano
Odprti dostop
High-resolution surface fluxes over the global ocean are needed to evaluate coupled atmosphere–ocean models and weather forecasting models, provide surface forcing for ocean models, understand the ...regional and temporal variations of the exchange of heat between the atmosphere and ocean, and provide a large-scale context for field experiments. Under the auspices of the World Climate Research Programme (WCRP) Global Energy and Water Cycle Experiment (GEWEX) Radiation Panel, the SEAFLUX Project has been initiated to investigate producing a high-resolution satellite-based dataset of surface turbulent fluxes over the global oceans to complement the existing products for surface radiation fluxes and precipitation. The SEAFLUX Project includes the following elements: a library of in situ data, with collocated satellite data to be used in the evaluation and improvement of global flux products; organized intercom-parison projects, to evaluate and improve bulk flux models and determination from the satellite of the input parameters; and coordinated evaluation of the flux products in the context of applications, such as forcing ocean models and evaluation of coupled atmosphere–ocean models. The objective of this paper is to present an overview of the status of global ocean surface flux products, the methodology being used by SEAFLUX, and the prospects for improvement of satellite-derived flux products.
We have determined the accumulation rates and carbon isotopic compositions (δ
13C) of long-chain (C
24–C
32) terrigenous plant wax fatty acids in 19 surface sediment samples geographically ...distributed throughout the Arabian Sea in order to assess the relationship between plant wax inputs and the surrounding monsoon wind systems. Both the accumulation rate data and the δ
13C data show that there are three primary eolian sources of plant waxes to the Arabian Sea: Africa, Asia, and the Arabian Peninsula. These sources correspond to the three major wind systems in this region: the summer (Southwest) monsoon, the winter (Northeast) monsoon, and the summer northwesterlies that blow over the Arabian Peninsula. In addition, plant waxes are fluvially supplied to the Gulf of Oman and the Eastern African margin by nearby rivers. Plant wax δ
13C values reflect the vegetation types of the continental source regions. Greater than 75% of the waxes from Africa and Asia are derived from C
4 plants. Waxes delivered by northwesterly winds reflect a greater influence (25–40%) of C
3 vegetation, likely derived from the Mesopotamian region. These data agree well with previously published studies of eolian dust deposition, particularly of dolomite derived from the Arabian Peninsula and the Mesopotamian region, in surface sediments of the Arabian Sea. The west-to-east gradient of plant wax δ
13C and dolomite accumulation rates are separately useful indicators of the relationship between the northwesterly winds and the winds of the Southwest monsoon. Combined, however, these two proxies could provide a powerful tool for the reconstruction of both southwest monsoon strength as well as Mesopotamian aridity.
Abstract
An inverse method is used to evaluate the information contained in sediment data for the Atlantic basin during the Last Glacial Maximum (defined here as the time interval 18–21 kyr before ...present). The data being considered are an updated compilation of the isotopic ratios 18O/16O (δ18O) and 13C/12C (δ13C) of fossil shells of benthic foraminifera (bottom-dwelling organisms). First, an estimate of the abyssal circulation in the modern Atlantic is obtained, which is consistent with (i) climatologies of temperature and salinity of the World Ocean Circulation Experiment, (ii) observational estimates of volume transport at specific locations, and (iii) the statements of a finite-difference geostrophic model. Second, estimates of water properties (δ18O of equilibrium calcite or δ18Oc and δ13C of dissolved inorganic carbon or δ13CDIC) derived from sediment data are combined with this circulation estimate to test their consistency with the modern flow. It is found that more than approximately 80% of water property estimates (δ18Oc or δ13CDIC) are compatible with the modern flow given their uncertainties. The consistency of glacial δ13CDIC estimates with the modern flow could be rejected after two assumptions are made: (i) the uncertainty in these estimates is ±0.1‰ (this uncertainty includes errors in sediment core chronology and oceanic representativity of benthic δ13C, which alone appears better than this value on average); and (ii) δ13CDIC in the glacial deep Atlantic was dominated by a balance between water advection and organic C remineralization. Measurements of δ13C on benthic foraminifera are clearly useful, but the current uncertainties in the distribution and budget of δ13CDIC in the glacial Atlantic must be reduced to increase the power of the test.
Tissue inhibitor of metalloproteinase (TIMP)-1 is a multifunctional peptide that has been implicated in the ovulatory process.
To assess the function of TIMP-1 during the periovulatory period in ...vivo, mice incapable of expressing the TIMP-1 gene product
were utilized. Twenty-three-day-old TIMP-1-deficient (n = 59) and wild-type (n = 61) female mice were injected with 5 IU eCG,
followed 48 h later by an ovulation-inducing dose of hCG (5 IU). Animals were killed at the time of hCG injection (0-h hCG),
at 12 h (12-h hCG), or at 24 h post-hCG (24-h hCG) administration. Serum was collected for the assessment of estradiol-17beta
(0-h hCG groups) or progesterone content (12- and 24-h hCG groups), while ovaries were removed for either histological preparation
or Northern analysis of TIMP-1, TIMP-2, and TIMP-3. The number of healthy and atretic follicles was determined in the 0-h
hCG groups, as was the number of oocytes released in the 24-h hCG group. TIMP-1-deficient females in the 0-h hCG group showed
reduced levels of ovarian TIMP-2 (0.29-fold decrease, p < 0.05) and TIMP-3 (3.0-fold decrease, p < 0.05) expression compared
to wild-type counterparts. No significant difference was detected between genotypes in the 0-h hCG group for number of healthy
or atretic follicles or for serum estradiol-17beta concentrations. Additionally, no significant differences were detected
between genotypes in the 12- and 24-h hCG groups for serum progesterone concentrations, ovarian TIMP-2 and TIMP-3 expression,
or number of oocytes released (24-h hCG group). To assess the effect of TIMP-1 on steroidogenesis in vitro, granulosa cells
were obtained from 23-day-old, eCG-primed TIMP-1-deficient and wild-type females. Addition of recombinant human TIMP-1 significantly
increased conditioned media estradiol-17beta concentrations in cell cultures from both mutant (1.32-fold over controls; p
= 0.02; n = 4) and wild-type females (1.16-fold over controls; p = 0.04; n = 3). It is concluded from this study that TIMP-1
may modulate ovarian TIMP-2 and TIMP-3 mRNA expression during folliculogenesis. In addition, TIMP-1 exhibits steroidogenic
activity in vitro, but no evidence was found for regulation of steroidogenesis in vivo.
Metalloproteinases are members of a family of proteinases that remodel the extracellular matrix throughout the body. To test
the hypothesis that metalloproteinases are regulated by ...gonadotropin-induced changes during follicular growth, rats were injected
with eCG (20 IU, s.c.), and ovaries and serum were collected at the time of eCG administration (0 h) and at 6, 12, 24, 36,
or 48 h later for analysis of metalloproteinase mRNA expression, metalloproteinase activity, and steroidogenesis. Serum estradiol
levels increased from 18.9 pg/ml at 0 h to 503.8 pg/ml at 48 h. Analysis of mRNA expression was performed for collagenase-3,
72-kDa gelatinase, and 92-kDa gelatinase (n = 3â4). For collagenase-3, eCG stimulated a 32-fold increase in collagenase-3
mRNA at 48 h after eCG injection as compared to that in ovaries collected at the time of eCG administration (i.e., 0-h control).
The mRNA levels for 72-kDa gelatinase were 2.8-fold compared to 0 h at 36 h after eCG treatment and returned to control levels
by 48 h after gonadotropin treatment. Levels of the 92-kDa mRNA expression peaked at 24 h (4.2-fold compared to 0 h) and returned
to control levels by 36 h. Gel zymography revealed 3 gelatinolytic bands corresponding to the gelatinases of approximately
72 kDa, 92 kDa, and 105 kDa. Analysis of metalloproteinase activity as the degradation of collagen or gelatin per ovary showed
an increase in gelatinolytic and collagenolytic activity between 12 and 48 h after eCG treatment. In summary, these findings
demonstrate that the gonadotropin induction of folliculogenesis results in changes in the metalloproteinases that may be responsible
for extracellular matrix remodeling associated with follicular growth.
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