255 research outputs found
Oxygen minimum zone-type biogeochemical cycling in the Cenomanian-Turonian Proto-North Atlantic across Oceanic Anoxic Event 2
Highlights
âą We present a 5 myr record of biogeochemical cycling in a Cretaceous upwelling area.
âą A novel quantitative approach for the evaluation of Fe speciation proxies was applied.
âą Ferruginous proxy signature reflects intense chemical weathering rather than anoxia.
âą Water column redox conditions evolved from oxic to nitrogenous to euxinic before OAE2.
âą Smaller seawater nitrate inventory facilitated sedimentary H2S release and euxinia.
Abstract
Oceanic Anoxic Events (OAEs) in Earth's history are regarded as analogues for current and future ocean deoxygenation, potentially providing information on its pacing and internal dynamics. In order to predict the Earth system's response to changes in greenhouse gas concentrations and radiative forcing, a sound understanding of how biogeochemical cycling differs in modern and ancient marine environments is required. Here, we report proxy records for iron (Fe), sulfur and nitrogen cycling in the Tarfaya upwelling system in the Cretaceous Proto-North Atlantic before, during and after OAE2 (âŒ93 Ma). We apply a novel quantitative approach to sedimentary Fe speciation, which takes into account the influence of terrigenous weathering and sedimentation as well as authigenic Fe (non-terrigenous, precipitated onsite) rain rates on Fe-based paleo-redox proxies. Generally elevated ratios of reactive Fe (i.e., bound to oxide, carbonate and sulfide minerals) to total Fe (FeHR/FeT) throughout the 5 million year record are attributed to transport-limited chemical weathering under greenhouse climate conditions. Trace metal and nitrogen isotope systematics indicate a step-wise transition from oxic to nitrogenous to euxinic conditions over several million years prior to OAE2. Taking into consideration the low terrigenous sedimentation rates in the Tarfaya Basin, we demonstrate that highly elevated FeHR/FeT from the mid-Cenomanian through OAE2 were generated with a relatively small flux of additional authigenic Fe. Evaluation of mass accumulation rates of reactive Fe in conjunction with the extent of pyritization of reactive Fe reveals that authigenic Fe and sulfide precipitation rates in the Tarfaya Basin were similar to those in modern upwelling systems. Because of a smaller seawater nitrate inventory, however, chemolithoautotrophic sulfide oxidation with nitrate was less efficient in preventing hydrogen sulfide release into the water column. As terrigenous weathering and sediment flux determine how much authigenic Fe is required to generate an anoxic euxinic or ferruginous proxy signature, we emphasize that both have to be taken into account when interpreting Fe-based paleo-redox proxies
Innate Lymphoid Cells as Regulators of Epithelial Integrity: Therapeutic Implications for Inflammatory Bowel Diseases
The occurrence of epithelial defects in the gut relevantly contributes to the pathogenesis of inflammatory bowel diseases (IBD), whereby the impairment of intestinal epithelial barrier integrity seems to represent a primary trigger as well as a disease amplifying consequence of the chronic inflammatory process. Besides epithelial cell intrinsic factors, accumulated and overwhelmingly activated immune cells and their secretome have been identified as critical modulators of the pathologically altered intestinal epithelial cell (IEC) function in IBD. In this context, over the last 10 years increasing levels of attention have been paid to the group of innate lymphoid cells (ILCs). This is in particular due to a preferential location of these rather newly described innate immune cells in close proximity to mucosal barriers, their profound capacity to secrete effector cytokines and their numerical and functional alteration under chronic inflammatory conditions. Aiming on a comprehensive and updated summary of our current understanding of the bidirectional mucosal crosstalk between ILCs and IECs, this review article will in particular focus on the potential capacity of gut infiltrating type-1, type-2, and type-3 helper ILCs (ILC1s, ILC2s, and ILC3s, respectively) to impact on the survival, differentiation, and barrier function of IECs. Based on data acquired in IBD patients or in experimental models of colitis, we will discuss whether the different ILC subgroups could serve as potential therapeutic targets for maintenance of epithelial integrity and/or mucosal healing in IBD
Regulation of Human Innate Lymphoid Cells in the Context of Mucosal Inflammation
Since their identification as a unique cell population, innate lymphoid cells (ILCs) have revolutionized our understanding of immune responses, leaving their impact on multiple inflammatory and fibrotic pathologies without doubt. Thus, a tightly controlled regulation of local ILC numbers and their activity is of crucial importance. Even though this has been extensively studied in murine ILCs in the last few years, our knowledge of human ILCs is still lagging behind. Our review article will therefore summarize recent insights into the function of human ILCs and will particularly focus on their regulation under inflammatory conditions. The quality and intensity of ILC involvement into local immune responses at mucosal sites of the human body can potentially be modulated via three different axes: (1) activation of tissue-resident mature ILCs, (2) plasticity and local transdifferentiation of specific ILC subsets, and (3) tissue migration and accumulation of peripheral ILCs. Despite a still ongoing scientific effort in this field, already existing data on the fate of human ILCs under different pathologic conditions clearly indicate that all three of these mechanisms are of relevance for the clinical course of chronic inflammatory and autoimmune diseases and might likewise provide new target structures for future therapeutic strategies
Functional Contribution and Targeted Migration of Group-2 Innate Lymphoid Cells in Inflammatory Lung Diseases: Being at the Right Place at the Right Time
During the last decade, group-2 innate lymphoid cells (ILC2s) have been discovered and successfully established as crucial mediators of lung allergy, airway inflammation and fibrosis, thus affecting the pathogenesis and clinical course of many respiratory diseases, like for instance asthma, cystic fibrosis and chronic rhinosinusitis. As an important regulatory component in this context, the local pulmonary milieu at inflammatory tissue sites does not only determine the activation status of lung-infiltrating ILC2s, but also influences their motility and migratory behavior. In general, many data collected in recent murine and human studies argued against the former concept of a very strict tissue residency of innate lymphoid cells (ILCs) and instead pointed to a context-dependent homing capacity of peripheral blood ILC precursors and the inflammation-dependent capacity of specific ILC subsets for interorgan trafficking. In this review article, we provide a comprehensive overview of the so far described molecular mechanisms underlying the pulmonary migration of ILC2s and thereby the numeric regulation of local ILC2 pools at inflamed or fibrotic pulmonary tissue sites and discuss their potential to serve as innovative therapeutic targets in the treatment of inflammatory lung diseases
Specific Heat Study of 1D and 2D Excitations in the Layered Frustrated Quantum Antiferromagnets CsCuClBr
We report an experimental and theoretical study of the low-temperature
specific heat and magnetic susceptibility of the layered anisotropic
triangular-lattice spin-1/2 Heisenberg antiferromagnets
CsCuClBr with = 0, 1, 2, and 4. We find that the ratio
of the exchange couplings ranges from 0.32 to , implying a
change (crossover or quantum phase transition) in the materials' magnetic
properties from one-dimensional (1D) behavior for to
two-dimensional (2D) behavior for behavior. For , realized for = 0, 1, and 4, we find a magnetic contribution to the
low-temperature specific heat, , consistent with spinon
excitations in 1D spin-1/2 Heisenberg antiferromagnets. Remarkably, for =
2, where implies a 2D magnatic character, we also observe
. This finding, which contrasts the prediction of made by standard spin-wave theories, shows that Fermi-like
statistics also plays a significant role for the magnetic excitations in
frustrated spin-1/2 2D antiferromagnets
Health status, use of healthcare, and socio-economic implications of cancer survivorship in Portugal : results from the fourth national health survey
Health status, use of healthcare, and socio-economic implications of cancer survivorship in Portugal: results from the Fourth National Health SurveyUnderstanding the morbidity and socio-economic implications of cancer survivorship is essential for a comprehensive management of oncological diseases. We compared cancer survivors (CS) with the general population regarding health status, use of healthcare resources and socio-economic condition.
We analyzed data from a representative sample of the Portuguese population aged a parts per thousand yen15 years (n = 35,229). We defined three groups of CS, according to the time since diagnosis and the latest cancer treatment: CS 1 diagnosis within 12 months of interview; CS 2 diagnosis more than 12 months before and treatment in the previous 12 months; CS 3 diagnosis and treatment more than 12 months before. These were compared with the general population, adjusting for differences in sex, age, and place of residence.
The prevalence of CS was 2.2 % (CS 1: 0.2 %; CS 2: 0.9 %, CS 3: 1.1 %). Self-perceived health status was worse among CS and short-time incapacity more frequent among CS 1 and CS 2. Health expenses were higher in the early stages of survivorship. Lower household income and financial difficulties were more frequent in CS 1 and CS 3 men, respectively.
This study confirmed the higher consumption of healthcare resources and worse financial situation among CS.
Our study provides valuable information for understanding the global impact of cancer survivorship.The authors thank the National Health Systems Observatory (Observatorio Nacional de Saude), National Institute of Health Dr. Ricardo Jorge (INSA), Ministry of Health and the National Institute of Statistics (INE) for providing the data (Ministerio da Saude, Instituto Nacional de Saude Dr. Ricardo Jorge; IP, Departamento de Epidemiologia/Instituto Nacional de Estatistica: Inquerito Nacional de Saude 2005/2006). Luis Pacheco-Figueiredo received a grant from the Fundacao para a Ciencia e a Tecnologia (SFRH/SINTD/60124/2009)
Fertility Ideals of Women and Men Across the Life Course
This paper explores the stability of womenâs and menâs fertility preferences across the life course. The data come from the first six waves of the German Family Panel (pairfam), which span the period from 2008/2009 until 2013/2014. In our analysis, fertility preferences are measured using the following question: âUnder ideal circumstances, how many children would you like to have?â The average number cited by both women and men is 2.2. With rising age, this number declines modestly. Relying on fixed-effects modelling, we find that neither partnership status nor economic circumstances have any causal effect on fertility preferences. However, as the number of children a respondent has increases, his or her ideal number of children is also likely to grow. Thus, fertility ideals appear to undergo changes over time, and are adjusted in line with the size of the respondentâs own family
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