Other Things Being Equal: A Paired Testing Study of Discrimination in Mortgage Lending

This article summarizes a recently completed study, funded by the U.S. Department of Housing and Urban Development (HUD) and conducted by the Urban Institute, of discrimination against black and Hispanic homebuyers when they visit mortgage lending institutions in two major metropolitan markets to make pre-application inquiries. It represents the first application of paired testing to rigorously measure discrimination in the mortgage lending process. The paired tests disclosed significant levels of adverse treatment on the basis of race and ethnicity, with African Americans and Hispanics receiving less information and assistance than comparable whites, even at this very early stage in the application process.

Ontogenetic Effects of Hatching Plasticity in the Spotted Salamander (Ambystoma maculatum) due to Egg and Larval Predators

The ability to respond plastically to the environment has allowed amphibians to evolve a response to spatial and temporal variation in predation threat (Benard 2004). Embroys exposed to egg predation are expected to hatch out earlier than their conspecifics. Larval predation can induce a suite of phenotypic changes including growing a larger tail area. When presented with cues from both egg and larval predators, embryos are expected to respond to the egg predator by hatching out earlier because the egg predator presents an immediate threat. However, hatching early may be costly in the larval environment in terms of development, morphology, and/or behavior. We created a laboratory experiment in which we exposed clutches of spotted salamander (Ambystoma maculatum) eggs to both egg (caddisfly larvae) and larval (A. opacum) predators to test this hypothesis. We recorded hatching time and stage and took developmental and morphological data of the animals a week after hatching. Larvae were entered into lethal predation trials with a larval predatory sunfish (Lepomis sp.) in order to study behavior. We found that animals exposed to the egg predator cues hatched out earlier and at earlier developmental stages than conspecifics regardless of whether there was a larval predator present. Animals exposed to larval predator cues grew relatively larger tails and survived longer in the lethal predation trials. However the group exposed to both predators showed a cost of early hatching in terms of lower tail area and shorter survival time in predation trials. The morphological and developmental effects measured of hatching plasticity were transient as there were no developmental or morphological differences between the treatment groups at metamorphosis. Hatching plasticity may be transient but it is important to the development and survival of many amphibians.

CARMA3 serves as a critical mediator of NF-kappaB in multiple signal transduction pathways

The central dogma of molecular biology dictates that DNA is transcribed into RNA, which is later translated into protein. One of the early activators in this process is the transcription factor NF-κB. We have determined that an NF-κB inducer, CARMA3, is required for proper neural tube closure, similar to other NF-κB inducers. Using a genetic knockout of CARMA3, we demonstrated that it is required for Gαq-coupled GPCR-induced NF-κB activation. This is facilitated through a MAPK and IKK phosphorylation-independent mechanism, most likely by controlling NEMO-associated ubiquitination. We have also shown that CARMA3 is required for EGF and HRG-induced NF-κB activation. This activation requires the activity of both EGFR and HER2, as well as PKC. Again, we observed no defect in IKK phosphorylation, although we determined a clear defect in IKK activation. Finally, we have begun to determine the role of CARMA3 to both EGFR and HER2-induced tumorigenicity. By overexpressing a constitutive active mutant of HER2 in our CARMA3 WT and KO MEF cells, we have shown CARMA3 is important for HER2-driven soft agar colony growth. We have also shown that knockdown of endogenous CARMA3 in the EGFR-overexpressing A431 cell line abolishes EGF-induced NF-κB activation. These same cells have a dramatically reduced capacity to form colonies in soft agar as well. Using both mouse xenografts and a transgenic model of HER2-induced breast cancer, we have initiated studies which will help to determine the role of CARMA3 to in vivo tumorigenesis. Collectively, this work reveals novel roles for the CARMA3 protein in development, GPCR and EGFR/HER2 signaling. It also suggests that CARMA3 is involved in EGFR/HER2 mediated tumorigenesis, possibly indicating a novel therapeutic target for use in treatment of cancer. ^

Establishment of a complex inflammatory and protumorigenic microenvironment in mouse pancreas through cyclooxygenase-2 overexpression

Chronic inflammation is an established risk factor in the pathogenesis of many cancers. Pancreatic ductal adenocarcinoma, a malignancy with a particularly dismal prognosis, is no exception. Cyclooxygenase-2, a key enzyme induced by tissue injury, has a critical role in the generation of bioactive lipids known as prostaglandins. COX-2 overexpression is a frequent finding in pancreatic cancer, chronic pancreatitis and pancreatic intraepithelial neoplasias. To explore mechanisms through which chronic inflammation establishes and maintains a protumorigenic environment, we designed a mouse model overexpressing COX-2 in pancreatic parenchyma (BK5.COX-2 mice). We discovered that constitutive expression of COX-2 has a number of important sequelae, including upregulation of additional eicosanoid-generating enzymes and proinflammatory cytokines. Many of these molecular alterations precede the onset of significant histopathological changes. Increased levels of prostaglandins E2, D2, and F2α, 5-, 12-, and 15-hydroxyeiosatetraenoic acid (HETEs) were documented in tumors and pancreata of younger transgenic mice. Using a TaqMan™ Mouse Immune Panel, we detected elevated mRNAs for a number of proinflammatory cytokines (e.g., TNFα, IL-1β, IL-6). ^ Histological examination revealed early changes in the pancreas with similarities to human chronic pancreatitis, including loss of acinar cells, appearance of metaplastic ducts, and increased deposition of stroma. As the lesions progress, features typical of dysplastic and neoplastic cells emerged within the metaplastic ductal complexes, including cellular and nuclear atypia, crowding of cells, and loss of normal tissue architecture. The amount of fibroinflammatory stroma increased considerably; numerous small vessels were evident. A number of immunocytes from both the myeloid and lymphoid lineages were identified in transgenic pancreata. Neutrophils were the earliest to infiltrate, followed shortly by macrophages and mast cells. B and T cells generally began to appear by 8–12 weeks, and organized aggregates of lymphoid cells were often found in advanced lesions. ^ We tested the efficacy of several chemopreventive agents in this model, including celecoxib, a COX-2 selective inhibitor, pentoxifylline, a cytokine inhibitor, curcumin, a polyphenol with antioxidant and anti-inflammatory properties, and GW2974, a dual EGFR/ErbB2 inhibitor. Effects on lesion development were modest in the GW2974 and pentoxifylline treated groups, but significant prevention effects were observed with curcumin and celecoxib. ^

OUT-OF-HOSPITAL CHILDBEARING CENTERS IN THE UNITED STATES: A DESCRIPTIVE STUDY OF THE DEMOGRAPHIC AND MEDICAL-OBSTETRIC CHARACTERISTICS OF WOMEN BEGINNING LABOR THEREIN 1972-1979

There is currently much interest in the appropriate use of obstetrical technology, cost containment and meeting consumers' needs for safe and satisfying maternity care. At the same time, there has been an increase in professionally unattended home births. In response, a new type of service, the out-of-hospital childbearing center (CBC) has been developed which is administratively and structurally separate from the hospital. In the CBC, maternity care is provided by certified nurse-midwives to carefully screened low risk childbearing families in conjunction with physician and hospital back-up.^ It was the purpose of this study to accomplish the following objectives: (1) To describe in a historical prospective study the demographic and medical-obstetric characteristics of patients laboring in eleven selected out-of-hospital childbearing centers in the United States from May 1, 1972, to December 15, 1979. Labor is defined as the onset of regular contractions as determined by the patient. (2) To describe any differences between those patients who require transfer to a back-up hospital and those who do not. (3) To describe administrative and service characteristics of eleven selected out-of-hospital childbearing centers in the United States. (4) To compare the demographic and medical-obstetric characteristics of women laboring in eleven selected out-of-hospital childbearing centers with a national sample of women of similar obstetric risk who according to birth certificates delivered legitimate infants in a hospital setting in the United States in 1972.^ Research concerning CBCs and supportive to the development of CBCs including studies which identified factors associated with fetal and perinatal morbidity and mortality, obstetrical risk screening, and the progress of technological development in obstetrics were reviewed. Information concerning the organization and delivery of care at each selected CBC was also collected and analyzed.^ A stratified, systematic sample of 1938 low risk women who began labor in a selected CBC were included in the study. These women were not unlike those described previously in small single center studies reported in the literature. The mean age was 25 years. Sixty-three per cent were white, 34 per cent Hispanic, 88 per cent married, 45 per cent had completed at least two years of college, nearly one-third were professionals and over a third were housewives. . . . (Author's abstract exceeds stipulated maximum length. Discontinued here with permission of school.) UMI ^

Effect of primary care availability and health insurance coverage on risk and cost of Preventable Hospitalizations in Harris County

Preventable Hospitalizations (PHs) are hospitalizations that can be avoided with appropriate and timely care in the ambulatory setting and hence are closely associated with primary care access in a community. Increased primary care availability and health insurance coverage may increase primary care access, and consequently may be significantly associated with risks and costs of PHs. Objective. To estimate the risk and cost of preventable hospitalizations (PHs); to determine the association of primary care availability and health insurance coverage with the risk and costs of PHs, first alone and then simultaneously; and finally, to estimate the impact of expansions in primary care availability and health insurance coverage on the burden of PHs among non-elderly adult residents of Harris County. Methods. The study population was residents of Harris County, age 18 to 64, who had at least one hospital discharge in a Texas hospital in 2008. The primary independent variables were availability of primary care physicians, availability of primary care safety net clinics and health insurance coverage. The primary dependent variables were PHs and associated hospitalization costs. The Texas Health Care Information Collection (THCIC) Inpatient Discharge data was used to obtain information on the number and costs of PHs in the study population. Risk of PHs in the study population, as well as average and total costs of PHs were calculated. Multivariable logistic regression models and two-step Heckman regression models with log-transformed costs were used to determine the association of primary care availability and health insurance coverage with the risk and costs of PHs respectively, while controlling for individual predisposing, enabling and need characteristics. Predicted PH risk and cost were used to calculate the predicted burden of PHs in the study population and the impact of expansions in primary care availability and health insurance coverage on the predicted burden. Results. In 2008, hospitalized non-elderly adults in Harris County had 11,313 PHs and a corresponding PH risk of 8.02%. Congestive heart failure was the most common PH. PHs imposed a total economic burden of $84 billion at an average of $7,449 per PH. Higher primary care safety net availability was significantly associated with the lower risk of PHs in the final risk model, but only in the uninsured. A unit increase in safety net availability led to a 23% decline in PH odds in the uninsured, compared to only a 4% decline in the insured. Higher primary care physician availability was associated with increased PH costs in the final cost model (β=0.0020; p<0.05). Lack of health insurance coverage increased the risk of PH, with the uninsured having 30% higher odds of PHs (OR=1.299; p<0.05), but reduced the cost of a PH by 7% (β=-0.0668; p<0.05). Expansions in primary care availability and health insurance coverage were associated with a reduction of about $1.6 million in PH burden at the highest level of expansion. Conclusions. Availability of primary care resources and health insurance coverage in hospitalized non-elderly adults in Harris County are significantly associated with the risk and costs of PHs. Expansions in these primary care access factors can be expected to produce significant reductions in the burden of PHs in Harris County.^

Novel Imaging-Based Techniques Reveal a Role for PD-1/PD-L1 in Tumor Immune Surveillance in the Lung

The binding of immune inhibitory receptor Programmed Death 1 (PD-1) on T cells to its ligand PD-L1 has been implicated as a major contributor to tumor induced immune suppression. Clinical trials of PD-L1 blockade have proven effective in unleashing therapeutic anti-tumor immune responses in a subset of patients with advanced melanoma, yet current response rates are low for reasons that remain unclear. Hypothesizing that the PD-1/PD-L1 pathway regulates T cell surveillance within the tumor microenvironment, we employed intravital microscopy to investigate the in vivo impact of PD-L1 blocking antibody upon tumor-associated immune cell migration. However, current analytical methods of intravital dynamic microscopy data lack the ability to identify cellular targets of T cell interactions in vivo, a crucial means for discovering which interactions are modulated by therapeutic intervention. By developing novel imaging techniques that allowed us to better analyze tumor progression and T cell dynamics in the microenvironment; we were able to explore the impact of PD-L1 blockade upon the migratory properties of tumor-associated immune cells, including T cells and antigen presenting cells, in lung tumor progression. Our results demonstrate that early changes in tumor morphology may be indicative of responsiveness to anti-PD-L1 therapy. We show that immune cells in the tumor microenvironment as well as tumors themselves express PD-L1, but immune phenotype alone is not a predictive marker of effective anti-tumor responses. Through a novel method in which we quantify T cell interactions, we show that T cells are largely engaged in interactions with dendritic cells in the tumor microenvironment. Additionally, we show that during PD-L1 blockade, non-activated T cells are recruited in greater numbers into the tumor microenvironment and engage more preferentially with dendritic cells. We further show that during PD-L1 blockade, activated T cells engage in more confined, immune synapse-like interactions with dendritic cells, as opposed to more dynamic, kinapse-like interactions with dendritic cells when PD-L1 is free to bind its receptor. By advancing the contextual analysis of anti-tumor immune surveillance in vivo, this study implicates the interaction between T cells and tumor-associated dendritic cells as a possible modulator in targeting PD-L1 for anti-tumor immunotherapy.

Integrated Data Sets of the EU FP5 Research Project ORFOIS: Origin and fate of biogenic particle fluxes in the ocean and their interactions with atmospheric CO2 concentrations as well as the marine sediment

For a reliable simulation of the time and space dependent CO2 redistribution between ocean and atmosphere an appropriate time dependent simulation of particle dynamics processes is essential but has not been carried out so far. The major difficulties were the lack of suitable modules for particle dynamics and early diagenesis (in order to close the carbon and nutrient budget) in ocean general circulation models, and the lack of an understanding of biogeochemical processes, such as the partial dissolution of calcareous particles in oversaturated water. The main target of ORFOIS was to fill in this gap in our knowledge and prediction capability infrastructure. This goal has been achieved step by step. At first comprehensive data bases (already existing data) of observations of relevance for the three major types of biogenic particles, organic carbon (POC), calcium carbonate (CaCO3), and biogenic silica (BSi or opal), as well as for refractory particles of terrestrial origin were collated and made publicly available.

(Figure 2) Organic carbon content, stable isotope ratios, TEX86 index and sea surface temperature reconstruction for the early Aptian of ODP Hole 198-1207B

The Cretaceous has long been recognized as a time when greenhouse conditions were fueled by elevated atmospheric CO2 and accompanied by perturbations of the global carbon cycle described as oceanic anoxic events (OAEs). Yet, the magnitude and frequency of temperature change during this interval of warm and equable climate are poorly constrained. Here we present a high-resolution record of sea-surface temperatures (SSTs) reconstructed using the TEX86 paleothermometer for a sequence of early Aptian organic-rich sediments deposited during the first Cretaceous OAE (OAE1a) at Shatsky Rise in the tropical Pacific. SSTs range from ~30 to ~36 °C and include two prominent cooling episodes of ~4 °C. The cooler temperatures reflect significant temperature instability in the tropics likely triggered by changes in carbon cycling induced by enhanced burial of organic matter. SST instability recorded during the early Aptian in the Pacific is comparable to that reported for the late Albian-early Cenomanian in the Atlantic, suggesting that such climate perturbations may have recurred during the Cretaceous with concomitant consequences for biota and the marine environment.

Gamma irradiation on Alstroemeria aurea G. in vitro rhizomes: : an approach to the appropriate dosage for breeding purposes

Gamma irradiation has been widely used as a breeding technique to obtain new cultivars in ornamental species such as Alstroemeria, where several cultivars have been obtained through rhizome radiation. The optimum dosage for an appropriate induction of mutation must be considered for breeding purposes and it depends mainly on plant susceptibility. Thus in this study in vitro cultured rhizomes of Alstroemeria aurea were irradiated with a gamma source using different dosages to evaluate the direct effect produced. Damage and number of rhizome sprouting were observed and recorded during 61 days after irradiation. At the end of this period, rhizomes were weighted and mortality was evaluated. Both mortality and weight increased depending on dosage. All irradiated rhizomes showed early sprouting in comparison with control (0 Gy) and no significant difference in final number of shoots after 61 days among irradiated treatments was observed. Bleaching and necrosis was observed in all irradiated rhizomes and was more evident at higher doses. LD50 was established at about 40 Gy and the optimum dosage to induce mutation was suggested between 2.5 and 5 Gy, when the growth was reduced in 50%, and probably this dosage could be used for breeding purposes.

Chlorophyll a concentration and zooplankton abundance and biomass below melting sea ice in the Amundsen Gulf

Early summer in the Arctic with extensive ice melt and break-up represents a dramatic change for sympagic-pelagic fauna below seasonal sea ice. As part of the International Polar Year-Circumpolar Flaw Lead system study (IPY-CFL), this investigation quantified zooplankton in the meltwater layer below landfast ice and remaining ice fauna below melting ice during June (2008) in Franklin Bay and Darnley Bay, Amundsen Gulf, Canada. The ice was in a state of advanced melt, with fully developed melt ponds. Intense melting resulted in a 0.3- to 0.5-m-thick meltwater layer below the ice, with a strong halocline to the Arctic water below. Zooplankton under the ice, in and below the meltwater layer, was sampled by SCUBA divers. Dense concentrations (max. 1,400 ind./m**3) of Calanus glacialis were associated with the meltwater layer, with dominant copepodid stages CIV and CV and high abundance of nauplii. Less abundant species included Pseudocalanus spp., Oithona similis and C. hyperboreus. The copepods were likely feeding on phytoplankton (0.5-2.3 mg Chl-a/m**3) in the meltwater layer. Ice amphipods were present at low abundance (<10 ind./m**2) and wet biomass (<0.2 g/m**2). Onisimus glacialis and Apherusa glacialis made up 64 and 51% of the total ice faunal abundance in Darnley Bay and Franklin Bay, respectively. During early summer, the autochthonous ice fauna becomes gradually replaced by allochthonous zooplankton, with an abundance boom near the meltwater layer. The ice amphipod bust occurs during late stages of melting and break-up, when their sympagic habitat is diminished then lost.

(Table 2) Concentration of phytoplankton pigments in Adventfjorden in spring and summer of 1997

The study was carried out from April 30 until July 13 of 1997 in Adventfjorden (Spitsbergen). Formation of a less saline and warmer surface water (~1 m thick) caused by melting of the ice was observed in the fjord during the first days of May. In summer the less saline surface layer was about 3 m thick. Euphotic depth measured under the ice sheet reached 12 m, whereas load of mineral matter brought with riverine discharge in summer (content of total particulate matter in the fjord reached 1.66 kg/m**2) dramatically reduced euphotic zone depth to 0.35 m. By pigment measurement three phases of phytoplankton development in Adventfjorden were distinguished: (1) spring bloom that has started under fast ice and reached maximum in the mid of May, (2) stagnation period in June, (3) increase of pigment concentration in July, what could indicate start of the next algae bloom. Analyses of chlorophylls and carotenoids revealed that diatoms (chl c, fucoxanthin), and green algae (chl b, lutein) dominated phytoplankton community in the fjord. Moreover, presence of peridinin indicates presence of Dinophyta and alloxanthin - occurence of Cryptophyta. In May and June 1997 phytoplankton appeared mainly in the surface of water, while in July, as a result of inflow of turbulent riverine waters into Adventfjorden, algae cells were pushed down and the highest numbers were observed at depth ~20 m. Great phaeopigments to chl a ratio (= 0.54) found in fjord seston in June and July probably shows strong impact of zooplankton grazing on phytoplankton development. High contribution of chlorophyllide a in porphyrin a poll in samples collected under fast ice (chlorophyllide a / chl a ratio = 0.18) reflects the final stage of algal communitie succession in ice, just before spring ice melt and release of biota to oceanic water. Chlorophyllide a content during summer was minor or not detectable, demonstrating that diatom cells were in good physiological condition. High chl a allomer / chl a ratio (average = 0.11 for the period investigated) confirms high oxygen concentration in environment of Adventfjorden.

Electromagnetic, rock magnetic, and geochemical properties of surficial sediments in Eckernförde Bay

Submarine groundwater discharge in coastal settings can massively modify the hydraulic and geochemical conditions of the seafloor. Resulting local anomalies in the morphology and physical properties of surface sediments are usually explored with seismo-acoustic imaging techniques. Controlled source electromagnetic imaging offers an innovative dual approach to seep characterization by its ability to detect pore-water electrical conductivity, hence salinity, as well as sediment magnetic susceptibility, hence preservation or diagenetic alteration of iron oxides. The newly developed electromagnetic (EM) profiler Neridis II successfully realized this concept for a first time with a high-resolution survey of freshwater seeps in Eckernförde Bay (SW Baltic Sea). We demonstrate that EM profiling, complemented and validated by acoustic as well as sample-based rock magnetic and geochemical methods, can create a crisp and revealing fingerprint image of freshwater seepage and related reductive alteration of near-surface sediments. Our findings imply that (1) freshwater penetrates the pore space of Holocene mud sediments by both diffuse and focused advection, (2) pockmarks are marked by focused freshwater seepage, underlying sand highs, reduced mud thickness, higher porosity, fining of grain size, and anoxic conditions, (3) depletion of Fe oxides, especially magnetite, is more pervasive within pockmarks due to higher concentrations of organic and sulfidic reaction partners, and (4) freshwater advection reduces sediment magnetic susceptibility by a combination of pore-water injection (dilution) and magnetite reduction (depletion). The conductivity vs. susceptibility biplot resolves subtle lateral litho- and hydrofacies variations.

Table 1: Discharge, mass flux, maximum velocity and ice thickness of glaciers from Dronning Maud Land, Antarctica

Mass transport and mass flux values for the different types of glaciers in the Sør-Rondane are calculated from computer models, based upon gravity data and geodetic stake velocity measurements. The results are interpreted in the light of a general flow line analysis, glacial geological investigations and of the ablation terms of the mass balance for Dronning Maud Land and Antarctica.

Chemistry and accumulation rates of Jurassic to early Cretaceous sediments from the central equatorial Pacific

Sedimentation in the central Pacific during the Jurassic and Early Cretaceous was dominated by abundant biogenic silica. A synthesis of the stratigraphy, lithology, petrology, and geochemistry of the radiolarites in Sites 801 and 800 documents the sedimentation processes and trends in the equatorial central Pacific from the Middle Jurassic through the Early Cretaceous. Paleolatitude and paleodepth reconstructions enable comparisons with previous DSDP sites and identification of the general patterns of sedimentation over a wide region of the Pacific. Clayey radiolarites dominated sedimentation on Pacific oceanic crust within tropical paleolatitudes from at least the latest Bathonian through Tithonian. Radiolarian productivity rose to a peak within 5° of the paleoequator, where accumulation rates of biogenic silica exceeded 1000 g/cm**2/m.y. Wavy-bedded radiolarian cherts developed in the upper Tithonian at Site 801 coinciding with the proximity of this site to the paleoequator. Ribbon-bedding of some radiolarian cherts exposed on Pacific margins may have formed from silicification of radiolarite deposited near the equatorial high-productivity zone where radiolarian/clay ratios were high. Silicification processes in sediments extensively mixed by bioturbation or enriched in clay or carbonate generally resulted in discontinuous bands or nodules of porcellanite or chert, e.g., a "knobby" radiolarite. Ribbon-bedded cherts require primary alternations of radiolarian-rich and clay-rich layers as an initial structural template, coupled with abundant biogenic silica in both layers. During diagenesis, migration of silica from clay-rich layers leaves radiolarian "ghosts" or voids, and the precipitation in adjacent radiolarite layers results in silicification of the inter-radiolarian matrix and infilling of radiolarian tests. Alternations of claystone and clay-rich radiolarian grainstone were deposited during the Callovian at Site 801 and during the Berriasian-Valanginian at Site 800, but did not silicify to form bedded chert. Carbonate was not preserved on the Pacific oceanic floor or spreading ridges during the Jurassic, perhaps due to an elevated level of dissolved carbon dioxide. During the Berriasian through Hauterivian, the carbonate compensation depth (CCD) descended to approximately 3500 m, permitting the accumulation of siliceous limestones at near-ridge sites. Carbonate accumulation rates exceeded 1500 g/cm**2/m.y. at sites above the CCD, yet there is no evidence of an equatorial carbonate bulge during the Early Cretaceous. In the Barremian and Aptian, the CCD rose, coincident with the onset of mid-plate volcanic activity. Abundance of Fe and Mn and the associated formation of authigenic Fe-smectite clays was a function of proximity to the spreading ridges, with secondary enrichments occurring during episodes of spreading-center reorganizations. Callovian radiolarite at Site 801 is anomalously depleted in Mn, which resulted either from inhibited precipitation of Mn-oxides by lower pH of interstitial waters induced by high dissolved oceanic CO2 levels or from diagenetic mobilization of Mn. Influx of terrigenous (eolian) clay apparently changed with paleolatitude and geological age. Cyclic variations in productivity of radiolarians and of nannofossils and in the influx of terrigenous clay are attributed to Milankovitch climatic cycles of precession (20,000 yr) and eccentricity (100,000 yr). Diagenetic redistribution of biogenic silica and carbonate enhanced the expression of this cyclic sedimentation. Jurassic and Lower Cretaceous sediments were deposited under oxygenated bottom-water conditions at all depths, accompanied by bioturbation and pervasive oxidation of organic carbon and metals. Despite the more "equable" climate conditions of the Mesozoic, the super-ocean of the Pacific experienced adequate deep-water circulation to prevent stagnation. Efficient nutrient recycling may have been a factor in the abundance of radiolarians in this ocean basin.