(Appendix B) Benthic foraminifera in Indian Ocean surface sediments

Multivariate analysis was performed on percentages of 46 species of unstained deep-sea benthic foraminifera from 131 core-top to near-core-top samples (322-5013 m) from across the Indian Ocean. Faunal data are combined with GEOSECS geochemical data to investigate any relationship between benthic foraminifera (assemblages and species) and deep-sea properties. In general, benthic foraminifera show a good correlation to surface productivity, organic carbon flux to the sea floor, deep-sea oxygenation and, to a lesser extent, to bottom temperature, without correlation with the water depths. The foraminiferal census data combined with geochemical data has enabled the division of the Indian Ocean into two faunal provinces. Province A occupies the northwestern Indian Ocean (Arabian Sea region) where surface primary production has a major maximum during the summer monsoon season and a secondary maximum during winter monsoon season that leads to high organic flux to the seafloor, making the deep-sea one of the most oxygen-deficient regions in the world ocean, with a pronounced oxygen minimum zone (OMZ). This province is dominated by benthic foraminifera characteristic of low oxygen and high organic food flux including Uvigerina peregrina, Robulus nicobarensis, Bolivinita pseudopunctata, Bolivinita sp., Bulimina aculeata, Bulimina alazanensis, Ehrenbergina carinata and Cassidulina carinata. Province B covers southern, southeastern and eastern parts of the Indian Ocean and is dominated by Nuttallides umbonifera, Epistominella exigua, Globocassidulina subglobosa, Uvigerina proboscidea, Cibicides wuellerstorfi, Cassidulina laevigata, Pullenia bulloides, Pullenia osloensis, Pyrgo murrhina, Oridorsalis umbonatus, Gyroidinoides (= Gyroidina) soldanii and Gyroidinoides cf. gemma suggesting well-oxygenated, cold deep water with low (oligotrophic) and pulsed food supply.

(Table, page 351-359) Chemical composition of manganese nodules and crusts from the Pacific and Indian Ocean

Chemical and mineralogical analyses of manganese nodules from a large number of widely spaced localities in the Pacific and Indian Oceans have shown that their mineralogy and chemical composition varies both areally and with depth of formation. This is considered to result from a number of factors, important among which are: (a) their proximity to continental or volcanic sources of elements; (b) the chemical environment of deposition, including the degree of oxygenation; and (c) local factors such as the upward migration of reduced manganese in sediments from certain areas. Sub-surface nodules appear to share the chemical characteristics of their surface counterparts, especially those from volcanic areas where sub-surface sources of elements are probably important.

Sea-surface temperature reconstruction of sediment cores from the Skagerrak

We attempt a reconstruction of salinity levels of the central Baltic Sea based on diatom assemblages, the isotopic composition of organic matter and sedimentological expression of anoxia over the last 10 000 years. We use the data to investigate the dependence of salinity levels on climate evolution and isostasy. Changes in salinity of surface and deep waters were most pronounced from 8400 to approximately 5000 cal. BP. Density stratification between salty deep and fresher surface waters caused the frequent development of anoxic conditions and deposition of laminated sediments on large parts of the sea floor in the central Baltic Sea, and dramatic changes in organic carbon-accumulation rates. From 5000 to 3100 cal. BP, the salinity of the basin decreased, oxygenation of deep sea floors was improved, and fertility of the sea surface was significantly reduced. This is reflected by low accumulation rates of organic carbon in bioturbated sediments. Since 2800 cal. BP, salinity rose again and anoxic periods were more common. Even though the major steps in environmental evolution in the Baltic Sea coincide with known patterns of climatic change of the North Atlantic realm over the last 10 000 years, we find no conclusive evidence for synchronous changes or linear responses on submillennial timescales. However, we note that major variations in our salinity records agree with temporal patterns of reconstructed summer warmth and winter precipitation in southern Scandinavia. Both types of record suggest that climate in the mid-Holocene was far from stable. Our data also confirm that climate evolution over the late Holocene had significant impact on environmental conditions in the Baltic Sea.

Simultaneous high-resolution pH and spectrophotometric recordings of oxygen binding in native blood microvolumes, link to supplementary material

Oxygen equilibrium curves have been widely used to understand oxygen transport in numerous organisms. A major challenge has been to monitor oxygen binding characteristics and concomitant pH changes as they occur in vivo, in limited sample volumes. Here we report a technique allowing highly resolved and simultaneous monitoring of pH and blood pigment saturation in minute blood volumes. We equipped a gas diffusion chamber with a broad range fibre optic spectrophotometer and a micro-pH optode and recorded changes of pigment oxygenation along PO2 and pH gradients to test the setup. Oxygen binding parameters derived from measurements in only 15 µl of haemolymph from the cephalopod Octopus vulgaris showed low instrumental error (0.93%) and good agreement with published data. Broad range spectra, each resolving 2048 data points, provided detailed insight into the complex absorbance characteristics of diverse blood types. After consideration of photobleaching and intrinsic fluorescence, pH optodes yielded accurate recordings and resolved a sigmoidal shift of 0.03 pH units in response to changing PO2 from 0-21 kPa. Highly resolved continuous recordings along pH gradients conformed to stepwise measurements at low rates of pH changes. In this study we showed that a diffusion chamber upgraded with a broad range spectrophotometer and an optical pH sensor accurately characterizes oxygen binding with minimal sample consumption and manipulation. We conclude that the modified diffusion chamber is highly suitable for experimental biologists who demand high flexibility, detailed insight into oxygen binding as well as experimental and biological accuracy combined in a single set up.

Bulk sediment parameter of three sediment cores from permafrost lowlands, Alaska Arctic Coastal Plain

Arctic lowland landscapes have been modified by thermokarst lake processes throughout the Holocene. Thermokarst lakes form as a result of ice-rich permafrost degradation and they may expand over time through thermal and mechanical shoreline erosion. We studied proximal and distal sedimentary records from a thermokarst lake located on the Arctic Coastal Plain of northern Alaska to reconstruct the impact of catchment dynamics and morphology on the lacustrine depositional environment and to quantify carbon accumulation in thermokarst lake sediments. Short cores were collected for analysis of pollen, sedimentological and geochemical proxies. Radiocarbon and Pb/Cs dating, as well as extrapolation of measured historic lake expansion rates, were applied to estimate a minimum lake age of ~ 1,400 calendar years BP. The pollen record is in agreement with the young lake age as it does not include evidence of the "alder high" that occurred in the region ~ 4.0 cal ka BP. The lake most likely initiated from a remnant pond in a drained thermokarst lake basin (DTLB) and deepened rapidly as evidenced by accumulation of laminated sediments. Increasing oxygenation of the water column as shown by higher Fe/Ti and Fe/S ratios in the sediment indicate shifts in ice regime with increasing water depth. More recently, the sediment source changed as the thermokarst lake expanded through lateral permafrost degradation, alternating from redeposited DTLB sediments, to increased amounts of sediment from eroding, older upland deposits, followed by a more balanced combination of both DTLB and upland sources. The characterizing shifts in sediment sources and depositional regimes in expanding thermokarst lakes were therefore archived in the thermokarst lake sedimentary record. This study also highlights the potential for Arctic lakes to recycle old carbon from thawing permafrost and thermokarst processes.

Efeito da oxigenação hiperbárica no reparo ósseo de ratos diabéticos

The chronic state of hyperglycemia due to diabetes mellitus affects multiples organs impairing life quality. In bone, diabetes alters strength and mineral density and also suppresses the osteoblast activity, leading to an unbalanced bone healing process. Hyperbaric oxygen therapy (HBO) is suggested as an adjuvant treatment to accelerate bone repair. This study evaluated the effects of HBO in the number of mast cells and in new bone formation at the initial stage of bone repair in normoglycemic and diabetic rats. It was hypothesized that HBO treatment may improve bone repair in diabetic bone. The rats were equally divided in four groups: Control (C); Control + HBO (CH); Diabetes (D) and Diabetes + HBO (DH). Diabetes was induced by streptozotocin (65mg/kg) and femoral bone defects were created thirty days after diabetes induction in all groups. HBO initiated immediately after surgery procedure and was performed daily, for 7 days, in the CH e DH groups. Seven days after surgery, all animals were euthanized. The femur diaphyses were removed, fixated, decalcified and processed for paraffin embedding. The semi-serial histological sections obtained were stained with Hematoxylin-Eosin (HE), Mallory Trichrome and Toluidine Blue. The qualitative analysis was conducted in the histology slides stained with HE, where it was evaluated the morphological aspects of bone repair in the lesion area, observing the presence of clot, inflammatory cells, granulation tissue, type of bone tissue, morphology of bone cells, and thickness and organization of bone trabeculae. In the slides stained with Mallory Trichrome and Toluidine Blue were evaluated the percentage of new bone formation and number of mast cells, respectively. The qualitative analysis showed that the CH group presented a more advanced stage of bone repair compared to the C group, showing thicker trabeculae and greater bone filling of the lesion area. In D and DH group, the lesion area was partially filled with new bone formation tissue and presented thinner trabeculae and fewer areas associated to osteoclasts compared to control group. The histomorphometric analysis showed a significant improvement in new bone formation (p<0.001) comparing CH (38.08 ± 4.05) and C (32.05 ± 5.51); C and D (24.62 ± 2.28 and CH and DH (27.14 ± 4.21) groups. In the normoglycemic rats there was a significant increasing in the number of mast cells (p<0.05) comparing C (8.06 ± 5.15) and CH (21.06 ± 4.91) groups. In conclusion, this study showed that diabetes impaired bone repair and HBO was only able to increase new bone formation and the number of mast cells in the normoglycemic animals.

Assessment of the Spatial and Temporal Distribution of Functional Connectivity in Resting-State BOLD fMRI

Recent research into resting-state functional magnetic resonance imaging (fMRI) has shown that the brain is very active during rest. This thesis work utilizes blood oxygenation level dependent (BOLD) signals to investigate the spatial and temporal functional network information found within resting-state data, and aims to investigate the feasibility of extracting functional connectivity networks using different methods as well as the dynamic variability within some of the methods. Furthermore, this work looks into producing valid networks using a sparsely-sampled sub-set of the original data.

In this work we utilize four main methods: independent component analysis (ICA), principal component analysis (PCA), correlation, and a point-processing technique. Each method comes with unique assumptions, as well as strengths and limitations into exploring how the resting state components interact in space and time.

Correlation is perhaps the simplest technique. Using this technique, resting-state patterns can be identified based on how similar the time profile is to a seed region’s time profile. However, this method requires a seed region and can only identify one resting state network at a time. This simple correlation technique is able to reproduce the resting state network using subject data from one subject’s scan session as well as with 16 subjects.

Independent component analysis, the second technique, has established software programs that can be used to implement this technique. ICA can extract multiple components from a data set in a single analysis. The disadvantage is that the resting state networks it produces are all independent of each other, making the assumption that the spatial pattern of functional connectivity is the same across all the time points. ICA is successfully able to reproduce resting state connectivity patterns for both one subject and a 16 subject concatenated data set.

Using principal component analysis, the dimensionality of the data is compressed to find the directions in which the variance of the data is most significant. This method utilizes the same basic matrix math as ICA with a few important differences that will be outlined later in this text. Using this method, sometimes different functional connectivity patterns are identifiable but with a large amount of noise and variability.

To begin to investigate the dynamics of the functional connectivity, the correlation technique is used to compare the first and second halves of a scan session. Minor differences are discernable between the correlation results of the scan session halves. Further, a sliding window technique is implemented to study the correlation coefficients through different sizes of correlation windows throughout time. From this technique it is apparent that the correlation level with the seed region is not static throughout the scan length.

The last method introduced, a point processing method, is one of the more novel techniques because it does not require analysis of the continuous time points. Here, network information is extracted based on brief occurrences of high or low amplitude signals within a seed region. Because point processing utilizes less time points from the data, the statistical power of the results is lower. There are also larger variations in DMN patterns between subjects. In addition to boosted computational efficiency, the benefit of using a point-process method is that the patterns produced for different seed regions do not have to be independent of one another.

This work compares four unique methods of identifying functional connectivity patterns. ICA is a technique that is currently used by many scientists studying functional connectivity patterns. The PCA technique is not optimal for the level of noise and the distribution of the data sets. The correlation technique is simple and obtains good results, however a seed region is needed and the method assumes that the DMN regions is correlated throughout the entire scan. Looking at the more dynamic aspects of correlation changing patterns of correlation were evident. The last point-processing method produces a promising results of identifying functional connectivity networks using only low and high amplitude BOLD signals.

High-speed label-free functional photoacoustic microscopy of mouse brain in action.

We present fast functional photoacoustic microscopy (PAM) for three-dimensional high-resolution, high-speed imaging of the mouse brain, complementary to other imaging modalities. We implemented a single-wavelength pulse-width-based method with a one-dimensional imaging rate of 100 kHz to image blood oxygenation with capillary-level resolution. We applied PAM to image the vascular morphology, blood oxygenation, blood flow and oxygen metabolism in both resting and stimulated states in the mouse brain.

The impact of gestational age and fetal weight on the risk of failure of spinal anesthesia for cesarean delivery.

BACKGROUND: There are limited data about spinal dosing for cesarean delivery in preterm parturients. We investigated the hypothesis that preterm gestation is associated with an increased incidence of inadequate spinal anesthesia for cesarean delivery compared with term gestation. METHODS: We searched our perioperative database for women who underwent cesarean delivery under spinal or combined spinal-epidural anesthesia with hyperbaric bupivacaine ⩾10.5mg. The primary outcome was the incidence of inadequate surgical anesthesia needing conversion to general anesthesia or repetition or supplementation of the block. We divided patients into four categories: <28, 28 to <32, 32 to <37 and ⩾37weeks of gestation. The chi-square test was used to compare failure rates and a multivariable regression analysis was performed to investigate potential confounders of the relationship between gestational age and failure. RESULTS: A total of 5015 patients (3387 term and 1628 preterm) were included. There were 278 failures (5.5%). The incidence of failure was higher in preterm versus term patients (6.4% vs. 5.1%, P=0.02). Failure rates were 10.8%, 7.7%, 5.3% and 5% for <28, 28 to <32, 32 to <37 and ⩾37weeks of gestation, respectively. In the multivariable model, low birth weight (P<0.0001), gestational age (P=0.03), ethnicity (P=0.02) and use of combined spinal-epidural anesthesia (P<0.0001) were significantly associated with failure. CONCLUSIONS: At standard spinal doses of hyperbaric bupivacaine used in our practice (⩾10.5mg), there were higher odds of inadequate surgical anesthesia in preterm parturients. When adjusting for potential confounders, low birth weight was the main factor associated with failure.

Le rôle des réponses cardiovasculaires et respiratoires sur la cognition chez les jeunes et les ainés sains

En plus de contribuer à améliorer la santé de façon générale, l’activité physique chronique pourrait modérer le déclin cognitif associé au vieillissement normal et pathologique (Colcombe et Kramer, 2003; Heyn et al., 2004). Plus précisément, la pratique à long terme d’activités cardiovasculaires aurait des effets positifs sur la cognition des ainés et plus particulièrement sur le contrôle attentionnel, un aspect précocement touché au cours du vieillissement (Raz, 2000; Bherer et al., 2008). Toutefois, les mécanismes par lesquels l’exercice physique aigu améliore la cognition demeurent limités. Malgré ses nombreuses implications théoriques et pratiques, la réponse aiguë de l’oxygénation cérébrale à l’exercice physique et sa relation avec la cognition sont trop peu étudiées. Cette thèse se consacre à cette question. Des études récentes en neuro-imagerie chez les jeunes adultes démontrent que la relation entre l’oxygénation cérébrale et l’intensité de l’exercice suit la forme d’un U inversé. Il existe un seuil au-delà duquel l’oxygénation cérébrale diminue avec l’augmentation de l’intensité de l’exercice. Supposant que les performances cognitives dépendent de la disponibilité de l’oxygène cérébral, cette relation en U inversé devrait affecter les performances cognitives. Avant de préciser le rôle exact de l’oxygénation cérébrale sur les fonctions cognitives, nous avons d’abord examiné le temps nécessaire pour que l’oxygénation cérébrale atteigne un état stable et la durée pendant laquelle cette période stable peut être maintenue lors de paliers de sept minutes à une puissance sous-maximale (40%, 60% et 85% de la puissance aérobie maximale). Nos résultats soulignent l’existence d’une relation inverse entre la durée de l’état stable et l’intensité de l’exercice. Suite à cette vérification méthodologique, la prochaine étape a été de tester la possible relation entre l’oxygénation cérébrale, l’intensité de l’exercice et les performances cognitives, au cours du processus de vieillissement. Les résultats de ces études démontrent que la chute de l’oxygénation cérébrale observée lors des exercices de haute intensité est associée avec une diminution des performances cognitives. Les résultats de cette thèse corrigent l’écart existant dans la documentation entre l’exercice, les fonctions cognitives et les mécanismes neurophysiologiques.

Laminated sediment cores in the Bering Sea

During the last glacial termination, the upper North Pacific Ocean underwent dramatic and rapid changes in oxygenation that lead to the transient intensification of oxygen minimum zones (OMZs), recorded by the widespread occurrence of laminated sediments on circum-Pacific continental margins. We present a new laminated sediment record from the mid-depth (1100 m) northern Bering Sea margin that provides insight into these deglacial OMZ maxima with exceptional, decadal-scale detail. Combined ultrahigh-resolution micro-X-ray-fluorescence (micro-XRF) data and sediment facies analysis of laminae reveal an alternation between predominantly terrigenous and diatom-dominated opal sedimentation. The diatomaceous laminae are interpreted to represent spring/summer productivity events related to the retreating sea ice margin.We identified five laminated sections in the deglacial part of our site. Lamina counts were carried out on these sections and correlated with the Bølling-Allerød and Preboreal phases in the North Greenland Ice Core (NGRIP) oxygen isotope record, indicating an annual deposition of individual lamina couplets (varves). The observed rapid decadal intensifications of anoxia, in particular within the Bølling-Allerød, are tightly coupled to short-term warm events through increases in regional export production. This dependence of laminae formation on warmer temperatures is underlined by a correlation with published Bering Sea sea surface temperature records and d18O data of planktic foraminifera from the Gulf of Alaska. The rapidity of the observed changes strongly implies a close atmospheric teleconnection between North Pacific and North Atlantic regions.We suggest that concomitant increases in export production and subsequent remineralization of organic matter in the Bering Sea, in combination with oxygen-poor waters entering the Being Sea, drove down oxygen concentrations to values below 0.1ml/l and caused laminae preservation. Calculated benthic-planktic ventilation ages show no significant variations throughout the last deglaciation, indicating that changes in formation rates or differing sources of North Pacific mid-depth waters are not prime candidates for strengthening the OMZ at our site. The age models established by our correlation procedure allow for the determination of calendar age control points for the Bølling-Allerød and the Preboreal that are independent of the initial radiocarbon-based chronology. Resulting surface reservoir ages range within 730-990 yr during the Bølling-Allerød, 800-1100 yr in the Younger Dryas, and 765-775 yr for the Preboreal.

Benthic foraminiferal record from Santa Barbara basin

The oxygen minimum zone (OMZ) of the late Quaternary California margin experienced abrupt and dramatic changes in strength and depth in response to changes in intermediate water ventilation, ocean productivity, and climate at orbital through millennial time scales. Expansion and contraction of the OMZ is exhibited at high temporal resolution (107-126 year) by quantitative benthic foraminiferal assemblage changes in two piston cores forming a vertical profile in Santa Barbara Basin (569 m, basin floor; 481 m, near sill depth) to 34 and 24 ka, respectively. Variation in the OMZ is quantified by new benthic foraminiferal groupings and new dissolved oxygen index based on documented relations between species and water-mass oxygen concentrations. Foraminiferal-based paleoenvironmental assessments are integrated with principal component analysis, bioturbation, grain size, CaCO3, total organic carbon, and d13C to reconstruct basin oxygenation history. Fauna responded similarly between the two sites, although with somewhat different magnitude and taxonomic expression. During cool episodes (Younger Dryas and stadials), the water column was well oxygenated, most strongly near the end of the glacial episode (17-16 ka; Heinrich 1). In contrast, the OMZ was strong during warm episodes (Bølling/Allerød, interstadials, and Pre-Boreal). During the Bølling/Allerød, the OMZ shoaled to <360 m of contemporaneous sea level, its greatest vertical expansion of the last glacial cycle. Assemblages were then dominated by Bolivina tumida, reflecting high concentrations of dissolved methane in bottom waters. Short decadal intervals were so severely oxygen-depleted that no benthic foraminifera were present. The middle to late Holocene (6-0 ka) was less dysoxic than the early Holocene.

Palynomorphs from the Lateglacial and Holocene of the Mt-Athos Basin, Aegean Sea

To unravel the climatic and environmental dynamics in the borderlands of the Aegean Sea during the early and middle Holocene, and notably for the interval of sapropel S1 (S1) formation, we have analysed terrestrial palynomorphs from a marine core in the northern Aegean Sea. The qualitative results were complemented by quantitative pollen-based climate reconstructions. A land-sea correlation was established based on pollen data and sediment lightness measurements from the same core, and previously published benthic foraminifer data from a nearby core. The borderlands of the Aegean Sea underwent a transition from an open vegetation to oak-dominated woodlands between ~10.4 and ~9.5 ka cal BP. A coeval increase in winter precipitation suggests that moisture availability was the main factor controlling Holocene reforestation. The ~50% higher winter precipitation during S1 formation relative to "pre-sapropelic" conditions suggests a strong contribution from the borderlands of the Aegean Sea to the freshwater surplus during S1 formation. The humid and mild winter conditions during S1 formation were repeatedly punctuated by short-term climatic events that caused a partial deforestation and a reorganisation within the broad-leaved arboreal vegetation. In the marine realm, these events are documented by improved benthic oxygenation. The strongest event represents the regional expression of the 8.2 ka cold event and led to an interruption in S1 formation. Except for the interval of S1 formation, the pollen-derived winter temperatures correlate with the smoothed GISP2 K+ series. They support the previously published, marine-based concept that the intensity of the Siberian High strongly controlled the winter climate in the Aegean region. During S1 formation in the Aegean Sea, however, climate conditions in the borderlands were more strongly affected by the monsoonally influenced climate system of the lower latitudes.

(Table S1) Geochemistry for sediment core MD02-2515

A high-resolution, 55-kyr long record of chalcophile and redox-sensitive trace element accumulation (Ag, Cd, Re, Mo) from MD02-2515, western Guaymas Basin, is investigated in conjunction with patterns in stratigraphy and productivity. High opal concentrations (~58 wt. %), representing increased diatom production, coincide with laminated sediments, and dilute the concentrations of organic carbon (Corg) and metals. A similarity between opal and normalized Corg, Ag and Cd concentrations suggests delivery to the sediments by diatom export production, while patterns in normalized Re and Mo accumulation suggest a different emplacement mechanism. Although Mo enrichment in organic-rich, laminated sediments typically represents anoxic conditions at other locations, Mo (and Re) in Guaymas Basin is enriched in nonlaminated and bioturbated sediments that are representative of oxygenated conditions. Adsorption onto Fe- and/or Mn-oxyhydroxide surfaces during oxygenation inadequately explains both the Re and Mo enrichments. Thus, recently published mechanisms invoking direct Re and Mo removal from the water column and bioturbation-assisted irrigation of Re into the sediments are used to explain the counterintuitive observations in Guaymas Basin. The MD02-2515 stratigraphic and proxy records are also different from other records in the northeast Pacific in that there is little correspondence with Greenland Dansgaard-Oeschger interstadials. There is some correlation with Heinrich events, suggesting that ventilation of intermediate waters and/or reduced productivity may be important in controlling stratigraphy and trace element accumulation. The results question whether MD02-2515 records can be compared to northeast Pacific open-margin records, especially before 17 kyr BP.