Regional conditions cause contrasting behaviour in U-isotope fractionation in black shales: Constraints for global ocean palaeo-redox reconstructions

The U-isotope system is a well-established palaeo-redox proxy that potentially constrains the global extent of marine anoxia during average as well as extreme redox events throughout Earth's history. A typical archive that forms underneath a reducing water column and acts as an intense U sink is organic-rich black shale. However, the degree to which black shale archives reflect the marine U-isotope signature is not well understood because U-isotope fractionation between U(VI)-bearing seawater and U(IV)-bearing black shales may vary as a function of local environmental conditions. Here, we present a combination of U-isotope and elemental concentration datasets, supported by a complementary Mo-isotope record, for the Furlo sedimentary section in Marche–Umbria, Italy and interrogate the combined systematics to unravel the mechanisms controlling the U-isotope fractionation factor between black shales and ambient seawater. We examine black shales deposited before and during Oceanic Anoxic Event 2 (OAE 2), which was one of the most extreme climatic perturbations of the Mesozoic Era that took place around the Cenomanian–Turonian boundary (Late Cretaceous, c. 94 Ma). The results of this study show that the U-isotope signature in the black shales deposited before OAE 2 was controlled by different mechanisms than the U-isotope ratios recorded in black shales deposited during OAE 2, with both stratigraphic intervals likely influenced by local environmental conditions. Probable local environmental changes include increased U reduction associated with biomass at or above the sediment–water interface and varying dissolved hydrogen sulphide concentrations in the water column and sediment. The overall results of this study confirm that black shales are a highly complex archive for U-isotope studies of past oceanic redox conditions, due to the sensitivity of the U-isotope fractionation mechanism to local environmental conditions, which are difficult to constrain. We propose the application of a ∆238Ushale-seawater of 0.6 ± 0.1 ‰ to black shale records deposited under locally constant euxinic conditions at non-restricted settings

Effects of in vitro purging with 4-hydroperoxycyclophosphamide on the hematopoietic and microenvironmental elements of human bone marrow

We describe the effects of 4-hydroperoxycyclophosphamide (4-HC) on the hematopoietic and stromal elements of human bone marrow. Marrow cells were exposed to 4-HC and then assayed for mixed (CFU-Mix), erythroid (BFU-E), granulomonocytic (CFU-GM), and marrow fibroblast (CFU-F) colony-forming cells and studied in the long-term marrow culture (LTMC) system. The inhibition of colony formation by 4-HC was dose and cell-concentration dependent. The cell most sensitive to 4-HC was CFU-Mix (ID50 31 mumol/L) followed by BFU-E (ID50 41 mumol/L), CFU-GM (ID50 89 mumol/L), and CFU-F (ID50 235 mumol/L). In LTMC, a dose-related inhibition of CFU-GM production was noted. Marrows treated with 300 mumol/L 4-HC were completely depleted of CFU-GM but were able to generate these progenitors in LTMC. Marrow stromal progenitors giving rise to stromal layers in LTMC, although less sensitive to 4-HC cytotoxicity, were damaged by 4-HC also in a dose-related manner. Marrows treated with 4-HC up to 300 mumol/L, gave rise to stromal layers composed of fibroblasts, endothelial cells, adipocytes, and macrophages. Cocultivation experiments with freshly isolated autologous hematopoietic cells showed that stromal layers derived from 4-HC-treated marrows were capable of sustaining the long-term production of CFU-GM as well as controls

High gain holmium-doped fibre amplifiers

We investigate the operation of holmium-doped fibre amplifiers (HDFAs) in the 2.1 µm spectral region. For the first time we demonstrate a diode-pumped HDFA. This amplifier provides a peak gain of 25 dB at 2040 nm with a 15 dB gain window spanning the wavelength range 2030-2100 nm with an external noise figure (NF) of 4-6 dB. We also compare the operation of HDFAs when pumped at 1950 nm and 2008 nm. The 1950 nm pumped HDFA provides 41 dB peak gain at 2060 nm with 15 dB of gain spanning the wavelength range 2050-2120 nm and an external NF of 7-10 dB. By pumping at the longer wavelength of 2008 nm the gain bandwidth of the amplifier is shifted to longer wavelengths and using this architecture a HDFA was demonstrated with a peak gain of 39 dB at 2090 nm and 15 dB of gain spanning the wavelength range 2050-2150 nm. The external NF over this wavelength range was 8-14 dB

Diversity and ecological guild analysis of the oil palm fungal microbiome across root, rhizosphere, and soil compartments

The rhizosphere microbiome is a major determinant of plant health, which can interact with the host directly and indirectly to promote or suppress productivity. Oil palm is one of the world’s most important crops, constituting over a third of global vegetable oil production. Currently there is little understanding of the oil palm microbiome and its contribution to plant health and productivity, with existing knowledge based almost entirely on culture dependent studies. We investigated the diversity and composition of the oil palm fungal microbiome in the bulk soil, rhizosphere soil, and roots of 2-, 18-, and 35-year old plantations in Selangor, Malaysia. The fungal community showed substantial variation between the plantations, accounting for 19.7% of community composition, with compartment (root, rhizosphere soil, and bulk soil), and soil properties (pH, C, N, and P) contributing 6.5 and 7.2% of community variation, respectively. Rhizosphere soil and roots supported distinct communities compared to the bulk soil, with significant enrichment of Agaricomycetes, Glomeromycetes, and Lecanoromycetes in roots. Several putative plant pathogens were abundant in roots in all the plantations, including taxa related to Prospodicola mexicana and Pleurostoma sp. The mycorrhizal status and dependency of oil palm has yet to be established, and using 18S rRNA primers we found considerable between-site variation in Glomeromycotinian community composition, accounting for 31.2% of variation. There was evidence for the selection of Glomeromycotinian communities in oil palm roots in the older plantations but compartment had a weak effect on community composition, accounting for 3.9% of variation, while soil variables accounted for 9% of community variation. While diverse Mucoromycotinian fungi were detected, they showed very low abundance and diversity within roots compared to bulk soil, and were not closely related to taxa which have been linked to fine root endophyte mycorrhizal morphology. Many of the fungal sequences showed low similarity to established genera, indicating the presence of substantial novel diversity with significance for plant health within the oil palm microbiome

Dynamic redox conditions control late Ediacaran metazoan ecosystems in the Nama Group, Namibia

The first appearance of skeletal metazoans in the late Ediacaran (~550 million years ago; Ma) has been linked to the widespread development of oxygenated oceanic conditions, but a precise spatial and temporal reconstruction of their evolution has not been resolved. Here we consider the evolution of ocean chemistry from ~550 to ~541. Ma across shelf-to-basin transects in the Zaris and Witputs Sub-Basins of the Nama Group, Namibia. New carbon isotope data capture the final stages of the Shuram/Wonoka deep negative C-isotope excursion, and these are complemented with a reconstruction of water column redox dynamics utilising Fe-S-C systematics and the distribution of skeletal and soft-bodied metazoans. Combined, these inter-basinal datasets provide insight into the potential role of ocean redox chemistry during this pivotal interval of major biological innovation.The strongly negative δ13C values in the lower parts of the sections reflect both a secular, global change in the C-isotopic composition of Ediacaran seawater, as well as the influence of 'local' basinal effects as shown by the most negative δ13C values occurring in the transition from distal to proximal ramp settings. Critical, though, is that the transition to positive δ13C values postdates the appearance of calcified metazoans, indicating that the onset of biomineralization did not occur under post-excursion conditions.Significantly, we find that anoxic and ferruginous deeper water column conditions were prevalent during and after the transition to positive δ13C that marks the end of the Shuram/Wonoka excursion. Thus, if the C isotope trend reflects the transition to global-scale oxygenation in the aftermath of the oxidation of a large-scale, isotopically light organic carbon pool, it was not sufficient to fully oxygenate the deep ocean.Both sub-basins reveal highly dynamic redox structures, where shallow, inner ramp settings experienced transient oxygenation. Anoxic conditions were caused either by episodic upwelling of deeper anoxic waters or higher rates of productivity. These settings supported short-lived and monospecific skeletal metazoan communities. By contrast, microbial (thrombolite) reefs, found in deeper inner- and mid-ramp settings, supported more biodiverse communities with complex ecologies and large skeletal metazoans. These long-lived reef communities, as well as Ediacaran soft-bodied biotas, are found particularly within transgressive systems, where oxygenation was persistent. We suggest that a mid-ramp position enabled physical ventilation mechanisms for shallow water column oxygenation to operate during flooding and transgressive sea-level rise. Our data support a prominent role for oxygen, and for stable oxygenated conditions in particular, in controlling both the distribution and ecology of Ediacaran skeletal metazoan communities

Identifying associations between diabetes and acute respiratory distress syndrome in patients with acute hypoxemic respiratory failure : an analysis of the LUNG SAFE database

Background: Diabetes mellitus is a common co-existing disease in the critically ill. Diabetes mellitus may reduce the risk of acute respiratory distress syndrome (ARDS), but data from previous studies are conflicting. The objective of this study was to evaluate associations between pre-existing diabetes mellitus and ARDS in critically ill patients with acute hypoxemic respiratory failure (AHRF). Methods: An ancillary analysis of a global, multi-centre prospective observational study (LUNG SAFE) was undertaken. LUNG SAFE evaluated all patients admitted to an intensive care unit (ICU) over a 4-week period, that required mechanical ventilation and met AHRF criteria. Patients who had their AHRF fully explained by cardiac failure were excluded. Important clinical characteristics were included in a stepwise selection approach (forward and backward selection combined with a significance level of 0.05) to identify a set of independent variables associated with having ARDS at any time, developing ARDS (defined as ARDS occurring after day 2 from meeting AHRF criteria) and with hospital mortality. Furthermore, propensity score analysis was undertaken to account for the differences in baseline characteristics between patients with and without diabetes mellitus, and the association between diabetes mellitus and outcomes of interest was assessed on matched samples. Results: Of the 4107 patients with AHRF included in this study, 3022 (73.6%) patients fulfilled ARDS criteria at admission or developed ARDS during their ICU stay. Diabetes mellitus was a pre-existing co-morbidity in 913 patients (22.2% of patients with AHRF). In multivariable analysis, there was no association between diabetes mellitus and having ARDS (OR 0.93 (0.78-1.11); p = 0.39), developing ARDS late (OR 0.79 (0.54-1.15); p = 0.22), or hospital mortality in patients with ARDS (1.15 (0.93-1.42); p = 0.19). In a matched sample of patients, there was no association between diabetes mellitus and outcomes of interest. Conclusions: In a large, global observational study of patients with AHRF, no association was found between diabetes mellitus and having ARDS, developing ARDS, or outcomes from ARDS. Trial registration: NCT02010073. Registered on 12 December 2013

Death in hospital following ICU discharge : insights from the LUNG SAFE study

Background: To determine the frequency of, and factors associated with, death in hospital following ICU discharge to the ward. Methods: The Large observational study to UNderstand the Global impact of Severe Acute respiratory FailurE study was an international, multicenter, prospective cohort study of patients with severe respiratory failure, conducted across 459 ICUs from 50 countries globally. This study aimed to understand the frequency and factors associated with death in hospital in patients who survived their ICU stay. We examined outcomes in the subpopulation discharged with no limitations of life sustaining treatments (‘treatment limitations’), and the subpopulations with treatment limitations. Results: 2186 (94%) patients with no treatment limitations discharged from ICU survived, while 142 (6%) died in hospital. 118 (61%) of patients with treatment limitations survived while 77 (39%) patients died in hospital. Patients without treatment limitations that died in hospital after ICU discharge were older, more likely to have COPD, immunocompromise or chronic renal failure, less likely to have trauma as a risk factor for ARDS. Patients that died post ICU discharge were less likely to receive neuromuscular blockade, or to receive any adjunctive measure, and had a higher pre- ICU discharge non-pulmonary SOFA score. A similar pattern was seen in patients with treatment limitations that died in hospital following ICU discharge. Conclusions: A significant proportion of patients die in hospital following discharge from ICU, with higher mortality in patients with limitations of life-sustaining treatments in place. Non-survivors had higher systemic illness severity scores at ICU discharge than survivors. Trial Registration: ClinicalTrials.gov NCT02010073

Single-frequency Nd:YAG laser with LG01 donut mode output

Laguerre-Gaussian (LG0n) laser beams with a donut-shaped profile are attracting growing interestdue to a wealth of applications in areas such as optical manipulation of particles, trapping and guiding of atoms, laser drilling and writing and super-resolution microscopy. Here we report a diode-end-pumped single-frequency Nd:YAG laser using a novel fiber-based pump beam conditioning element to achieve lasing on the lowest order donut (LG01) mode. The pump conditioning element was fabricated from a capillary (hollow-core) silica fiber with a 200 µm outer diameter and a 105 µm diameter inner air hole. The fiber was tapered and spliced to a fiber-coupled laser diode with a maximum output power of 4 W at 808 nm. The capillary fiber yielded ~3.5 W of output in a beam with a ring-shaped near-field profile. The latter was imaged into a Nd:YAG rod in a two-mirror plano-concave resonator to selectively excite the LG01 mode. The laser produced up to 1.71 W of multi-axial-mode output at 1064 nm for 3.5 W of incident pump power. The corresponding slope efficiency was 57%. Single-axial-mode operation was achieved by inserting quarter-wave plates at both ends of the Nd:YAG rod to suppress spatial hole- burning together with an intracavity etalon. Using this set-up, we obtained 810 mW of single-frequency LG01 mode output with a well-defined sense of spiral phase for ~3.1 W of incident pump power. The beam propagation factor (M2) was measured to be ~2.09 and hence in close agreement with the theory. The prospects for further improvement in performance will be discussed