Infective endocarditis in pediatric patients: a decade of insights from a leading Spanish heart surgery reference center.

Infective endocarditis (IE) is a rare disease in children and is associated with significant morbidity and mortality. In recent years, significant changes have occurred in pediatric care that could have influenced the microbiology and presentation of IE. The aim of this work was to study epidemiological, microbiological, and clinical features of IE treated at a Pediatric Cardiac Surgery Reference Center located in Madrid (Spain) in a 10-years' period. A descriptive observational retrospective study was performed, including pediatric patients < 16 years old with definite or possible IE admitted to a reference center between January 2012 and December 2021. Thirty-two IE episodes were identified. Twenty-eight (87.5%) had congenital heart disease (CHD), 8 (25.0%) were preterm infants, 1 (3.1%) was immunocompromised and 6 (18.8%) had other chronic conditions; in 11 (34.4%) episodes more than one underlying condition was associated. In 20 (62.5%) episodes there was an indwelling central venous catheter (CVC); children with other comorbidities (preterm, immunocompromised, other chronic conditions) were more likely to have a CVC at diagnosis compared with patients with isolated CHD (p < 0.001). Thirty-six microbiological isolates were obtained in the 32 episodes; 4 (12.5%) episodes had 2 isolated microorganisms. Microbiological isolates were 20 (55.6%) Gram-positive bacteria (GPB), 10 (27.8%) non-HACEK Gram-negative bacteria (GNB), 1 (2.8%) HACEK-group bacterium, 4 (11.1%) fungi and 1 (2.8%) Coxiella burnetii. In 10 (31.3%) episodes, patients were colonized by multidrug-resistant bacteria (MDRB) and the etiology of IE in 3 (30.0%) of those episodes was the colonizing MDRB. MDRB colonization was associated with MDRB IE (p = 0.007). The most common complication was septic embolism: 11 (34.4%) episodes (9 pulmonary and 2 cerebral). In-hospital mortality was 6.3% (n = 2), all of them due to underlying conditions and not to IE or its complications. Clinical features and complications of IE episodes caused by non-HACEK GNB and those caused by GPB were compared, finding no statistically significant differences.    Conclusion: Risk factors for developing IE, the proportion of embolic complications, and mortality rate were consistent with previously published findings. Proportion of IE cases attributed to non-HACEK GNB was higher than previously reported, suggesting an evolving epidemiology of IE. One-third of children colonized with MDRB subsequently developed IE caused by the same MDRB strains, so empirical coverage of MDRB organisms must be considered when IE is suspected in MDRB colonized patients. No significant differences in clinical features and complications were observed when comparing IE episodes caused by non-HACEK GNB and those caused by GPB, however larger cohort studies are needed. What is Known: • Infective endocarditis (IE) is a rare disease in children, associated with significant morbidity and mortality. • The main risk factor for developing IE in children is an underlying congenital heart disease. What is New: • With current changing epidemiology in pediatric IE, a higher proportion of IE caused by non-HACEK Gram-negative bacteria should be expected. • A significant percentage of children colonized by multidrug-resistant bacteria can develop an IE due to those bacteria.

Mercury Contamination Challenges the Behavioral Response of a Keystone Species to Arctic Climate Change.

Combined effects of multiple, climate change-associated stressors are of mounting concern, especially in Arctic ecosystems. Elevated mercury (Hg) exposure in Arctic animals could affect behavioral responses to changes in foraging landscapes caused by climate change, generating interactive effects on behavior and population resilience. We investigated this hypothesis in little auks (Alle alle), a keystone Arctic seabird. We compiled behavioral data for 44 birds across 5 years using accelerometers while also quantifying blood Hg and environmental conditions. Warm sea surface temperature (SST) and low sea ice coverage reshaped time activity budgets (TABs) and diving patterns, causing decreased resting, increased flight, and longer dives. Mercury contamination was not associated with TABs. However, highly contaminated birds lengthened interdive breaks when making long dives, suggesting Hg-induced physiological limitations. As dive durations increased with warm SST, subtle toxicological effects threaten to increasingly constrain diving and foraging efficiency as climate change progresses, with ecosystem-wide repercussions.

Overexpression of wild type RRAS2, without oncogenic mutations, drives chronic lymphocytic leukemia.

BACKGROUND: Chronic lymphocytic leukemia (CLL) is the most frequent, and still incurable, form of leukemia in the Western World. It is widely accepted that cancer results from an evolutionary process shaped by the acquisition of driver mutations which confer selective growth advantage to cells that harbor them. Clear examples are missense mutations in classic RAS genes (KRAS, HRAS and NRAS) that underlie the development of approximately 13% of human cancers. Although autonomous B cell antigen receptor (BCR) signaling is involved and mutations in many tumor suppressor genes and oncogenes have been identified, an oncogenic driver gene has not still been identified for CLL. METHODS: Conditional knock-in mice were generated to overexpress wild type RRAS2 and prove its driver role. RT-qPCR analysis of a human CLL sample cohort was carried out to measure RRAS2 transcriptional expression. Sanger DNA sequencing was used to identify a SNP in the 3'UTR region of RRAS2 in human CLL samples. RNAseq of murine CLL was carried out to identify activated pathways, molecular mechanisms and to pinpoint somatic mutations accompanying RRAS2 overexpression. Flow cytometry was used for phenotypic characterization and shRNA techniques to knockdown RRAS2 expression in human CLL. RESULTS: RRAS2 mRNA is found overexpressed in its wild type form in 82% of the human CLL samples analyzed (n = 178, mean and median = 5-fold) as well as in the explored metadata. A single nucleotide polymorphism (rs8570) in the 3'UTR of the RRAS2 mRNA has been identified in CLL patients, linking higher expression of RRAS2 with more aggressive disease. Deliberate overexpression of wild type RRAS2 in mice, but not an oncogenic Q72L mutation in the coding sequence, provokes the development of CLL. Overexpression of wild type RRAS2 in mice is accompanied by a strong convergent selection of somatic mutations in genes that have been identified in human CLL. R-RAS2 protein is physically bound to the BCR and mediates BCR signals in CLL. CONCLUSIONS: The results indicate that overexpression of wild type RRAS2 is behind the development of CLL.

Sex-specific costs of reproduction on survival in a long-lived seabird.

Costs of reproduction on survival have captured the attention of researchers since life history theory was formulated. Adults of long-lived species may increase survival by reducing their breeding effort or even skipping reproduction. In this study, we aimed to evaluate the costs of current reproduction on survival and whether skipping reproduction increases adult survival in a long-lived seabird. We used capture-mark-recapture data (1450 encounters) from two populations of Bulwer's petrel (Bulweria bulwerii), breeding in the Azores and Canary Islands, North Atlantic Ocean. Using a multi-event model with two different breeding statuses (breeders versus non-breeders), we calculated probabilities of survival and of transitions between breeding statuses, evaluating potential differences between sexes. Females had lower survival probabilities than males, independent of their breeding status. When considering breeding status, breeding females had lower survival probabilities than non-breeding females, suggesting costs of reproduction on survival. Breeding males had higher survival probabilities than non-breeding males, suggesting that males do not incur costs of reproduction on survival and that only the highest quality males have access to breeding. The highest and the lowest probabilities of skipping reproduction were found in breeding males from the Azores and in breeding males from the Canary Islands, respectively. Intermediate values were observed in the females from both populations. This result is probably due to differences in the external factors affecting both populations, essentially predation pressure and competition. The existence of sex-specific costs of reproduction on survival in several populations of this long-lived species may have important implications for species population dynamics.

Aldehyde Dehydrogenase 2 (ALDH2) in Rat Fatty Liver Cold Ischemia Injury.

Institut George Lopez-1 (IGL-1) and Histidine-tryptophan-ketoglutarate (HTK) solutions are proposed as alternatives to UW (gold standard) in liver preservation. Their composition differs in terms of the presence/absence of oncotic agents such as HES or PEG, and is decisive for graft conservation before transplantation. This is especially so when fatty (steatotic) livers are used since these grafts are more vulnerable to ischemia insult during conservation. Their composition determines the extent of the subsequent reperfusion injury after transplantation. Aldehyde dehydrogenase-2 (ALDH2), a mitochondrial enzyme, has been reported to play a protective role in warm ischemia-reperfusion injury (IRI), but its potential in fatty liver cold ischemic injury has not yet been investigated. We evaluated the relevance of ALDH2 activity in cold ischemia injury when fatty liver grafts from Zucker Obese rats were preserved in UW, HTK, and IGL-1 solutions, in order to study the mechanisms involved. ALDH2 upregulation was highest in livers preserved in IGL-1. It was accompanied by a decrease in transaminases, apoptosis (Caspase 3 and TUNEL assay), and lipoperoxidation, which was concomitant with the effective clearance of toxic aldehydes such as 4-hydroxy-nonenal. Variations in ATP levels were also determined. The results were consistent with levels of NF-E2 p45-related factor 2 (Nrf2), an antioxidant factor. Here we report for the first time the relevance of mitochondrial ALDH2 in fatty liver cold preservation and suggest that ALDH2 could be considered a potential therapeutic target or regulator in clinical transplantation.

Cytoprotective Mechanisms in Fatty Liver Preservation against Cold Ischemia Injury: A Comparison between IGL-1 and HTK.

Institute Goeorges Lopez 1 (IGL-1) and Histidine-Tryptophan-Ketoglutarate (HTK) preservation solutions are regularly used in clinical for liver transplantation besides University of Wisconsin (UW) solution and Celsior. Several clinical trials and experimental works have been carried out comparing all the solutions, however the comparative IGL-1 and HTK appraisals are poor; especially when they deal with the underlying protection mechanisms of the fatty liver graft during cold storage. Fatty livers from male obese Zücker rats were conserved for 24 h at 4 °C in IGL-1 or HTK preservation solutions. After organ recovery and rinsing of fatty liver grafts with Ringer Lactate solution, we measured the changes in mechanistic target of rapamycin (mTOR) signaling activation, liver autophagy markers (Beclin-1, Beclin-2, LC3B and ATG7) and apoptotic markers (caspase 3, caspase 9 and TUNEL). These determinations were correlated with the prevention of liver injury (aspartate and alanine aminostransferase (AST/ALT), histology) and mitochondrial damage (glutamate dehydrogenase (GLDH) and confocal microscopy findings). Liver grafts preserved in IGL-1 solution showed a marked reduction on p-TOR/mTOR ratio when compared to HTK. This was concomitant with significant increased cyto-protective autophagy and prevention of liver apoptosis, including inflammatory cytokines such as HMGB1. Together, our results revealed that IGL-1 preservation solution better protected fatty liver grafts against cold ischemia damage than HTK solution. IGL-1 protection was associated with a reduced liver damage, higher induced autophagy and decreased apoptosis. All these effects would contribute to limit the subsequent extension of reperfusion injury after graft revascularization in liver transplantation procedures.

The Relevance of the UPS in Fatty Liver Graft Preservation: A New Approach for IGL-1 and HTK Solutions.

The 26S proteasome is the central proteolytic machinery of the ubiquitin proteasome system (UPS), which is involved in the degradation of ubiquitinated protein substrates. Recently, UPS inhibition has been shown to be a key factor in fatty liver graft preservation during organ cold storage using University of Wisconsin solution (UW) and Institute Georges Lopez (IGL-1) solutions. However, the merits of IGL-1 and histidine-tryptophan-ketoglutarate (HTK) solutions for fatty liver preservation have not been compared. Fatty liver grafts from obese Zücker rats were preserved for 24 h at 4 °C. Aspartate aminotransferase and alanine aminotransferase (AST/ALT), glutamate dehydrogenase (GLDH), ATP, adenosine monophosphate protein kinase (AMPK), e-NOS, proteasome activity and liver polyubiquitinated proteins were determined. IGL-1 solution prevented ATP breakdown during cold-storage preservation of steatotic livers to a greater extent than HTK solution. There were concomitant increases in AMPK activation, e-NOS (endothelial NOS (NO synthase)) expression and UPS inhibition. UPS activity is closely related to the composition of the solution used to preserve the organ. IGL-1 solution provided significantly better protection against ischemia-reperfusion for cold-stored fatty liver grafts than HTK solution. The effect is exerted through the activation of the protective AMPK signaling pathway, an increase in e-NOS expression and a dysregulation of the UPS.

Epidemiology of musculoskeletal pain in a pediatric emergency department.

The objectives of this study were (1) to determine the percentage of emergency department (ED) visits due to musculoskeletal pain (MSP) by children 3-14 years of age during a period of 1 year; (2) to determine the most frequent presenting complaints; and (3) to characterize their etiology. A cross-sectional study was performed on children aged 3-14(11/12) years attended at the ED of a tertiary hospital due to MSP. The demographic and clinical characteristics of the patients were reviewed 5 days each month for 12 consecutive months. Study days were selected by computer-generated simple random sampling. Out of 4,531 visits to the ED, 826 were due to MSP (18.2 %; 95 % CI 17.1-19.4 %). When compared with children with no skeletal complaints, children with MSP had a similar sex distribution but were older (mean ± SD 7 ± 3.5 years vs 9.9 ± 3.1 years; p < 0.0001). The most common complaints were pain at the wrist (19 %), ankle (19 %) and finger (15 %). The most common etiology was trauma (88.4 %), including contusions (38 %), fractures (21 %) and sprains (18 %). Children with hip (6.7 ± 3 years; p < 0.0001) and elbow (7.8 ± 3.5 years; p < 0.0001) complaints were younger than children with pain in other locations, whereas children with wrist pain (10.5 ± 2.6 years; p < 0.002) and joint sprains (10.7 ± 2.7 years; p < 0.0001) were older. Fractures were more frequent in boys (64 vs 36 %, p = 0.008; OR 1.6; CI 1.1-2.2). Visits to the ED due to MSP increased with age. Pain at three locations represented 50 % of the presenting complaints. Trauma was the principal etiology, but fractures only represented one-fifth of the total.

Desensitizing the autonomic nervous system to mitigate anti-GD2 monoclonal antibody side effects.

Background: Anti-GD2 monoclonal antibodies (mAbs) have shown to improve the overall survival of patients with high-risk neuroblastoma (HR-NB). Serious adverse events (AEs), including pain, within hours of antibody infusion, have limited the development of these therapies. In this study, we provide evidence of Autonomic Nervous System (ANS) activation as the mechanism to explain the main side effects of anti-GD2 mAbs. Methods: Through confocal microscopy and computational super-resolution microscopy experiments we explored GD2 expression in postnatal nerves of infants. In patients we assessed the ANS using the Sympathetic Skin Response (SSR) test. To exploit tachyphylaxis, a novel infusion protocol (the Step-Up) was mathematically modelled and tested. Results: Through confocal microscopy, GD2 expression is clearly visible in the perineurium surrounding the nuclei of nerve cells. By computational super-resolution microscopy experiments we showed the selective expression of GD2 on the cell membranes of human Schwann cells in peripheral nerves (PNs) significantly lower than on NB. In patients, changes in the SSR were observed 4 minutes into the anti-GD2 mAb naxitamab infusion. SSR latency quickly shortened followed by gradual decrease in the amplitude before disappearance. SSR response did not recover for 24 hours consistent with tachyphylaxis and absence of side effects in the clinic. The Step-Up protocol dissociated on-target off-tumor side effects while maintaining serum drug exposure. Conclusion: We provide first evidence of the ANS as the principal non-tumor target of anti-GD2 mAbs in humans. We describe the development and modeling of the Step-Up protocol exploiting the tachyphylaxis phenomenon we demonstrate in patients using the SSR test.

Spatial distribution of selenium-mercury in Arctic seabirds.

Mercury (Hg) is a metallic trace element toxic for humans and wildlife that can originate from natural and anthropic sources. Hg spatial gradients have been found in seabirds from the Arctic and other oceans, suggesting contrasting toxicity risks across regions. Selenium (Se) plays a protective role against Hg toxicity, but its spatial distribution has been much less investigated than that of Hg. From 2015 to 2017, we measured spatial co-exposure of Hg and Se in blood samples of two seabird species, the Brünnich's guillemot (Uria lomvia) and the black-legged kittiwake (Rissa tridactyla) from 17 colonies in the Arctic and subarctic regions, and we calculated their molar ratios (Se:Hg), as a measure of Hg sequestration by Se and, therefore, of Hg exposure risk. We also evaluated concentration differences between species and ocean basins (Pacific-Arctic and Atlantic-Arctic), and examined the influence of trophic ecology on Hg and Se concentrations using nitrogen and carbon stable isotopes. In the Atlantic-Arctic ocean, we found a negative west-to-east gradient of Hg and Se for guillemots, and a positive west-to-east gradient of Se for kittiwakes, suggesting that these species are better protected from Hg toxicity in the European Arctic. Differences in Se gradients between species suggest that they do not follow environmental Se spatial variations. This, together with the absence of a general pattern for isotopes influence on trace element concentrations, could be due to foraging ecology differences between species. In both oceans, the two species showed similar Hg concentrations, but guillemots showed lower Se concentrations and Se:Hg than kittiwakes, suggesting a higher Hg toxicity risk in guillemots. Within species, neither Hg, nor Se or Se:Hg differed between both oceans. Our study highlights the importance of considering Se together with Hg, along with different species and regions, when evaluating Hg toxic effects on marine predators in international monitoring programs.

Comparative Analysis of Very Reduced vs Full Dose BCG Treatment for High-Risk Non-Muscle Invasive Bladder Cancer: A Contemporary Experience from Chile.

BACKGROUND: Adjuvant bacillus Calmette-Guérin (BCG) is recommended for high-risk (HR) non-muscle invasive bladder cancer (NMIBC), but BCG shortages have led to exploration of reduced-dose regimens and shortened maintenance durations out of necessity, with limited data on treatment efficacy in Latin America. OBJECTIVE: Oncological outcomes of HR-NMIBC patients treated with reduced (RD,1/4th dose) vs full dose (FD) BCG instillations of Danish Strain 1331 BCG. METHODS: We performed a retrospective study of HR-NMIBC patients treated with BCG between 2003 and 2022 at our center in Santiago Chile. We stratified patients according to either RD (1/4th dose) or FD BCG. Univariate and multivariable Cox regression models were used to predict recurrence. Kaplan-Meier method was used to calculate survival estimates. RESULTS: Of a total of 200 patients, 116 (58%) had RD and 84 (42%) FD BCG. Median follow-up was 57 months (IQR: 29-100). Patients who received FD BCG had a lower risk of recurrence (HR: 0.41, 95% CI 0.22-0.74) and high-grade (HG)-recurrence (HR: 0.30, 95% CI 0.15-0.61; p = 0.001). More patients in the RD vs FD group progressed to MIBC (10/84 vs 2/116; p = 0.18). Additionally, patients were less likely to stop BCG treatment in the RD group compared to the FD group due to toxicity (5% vs 11%, p = 0.14). CONCLUSIONS: A 1/4th dose of Danish Strain 1331 BCG treatment was associated with worse recurrence free rate and HG-recurrence rate in our cohort. Patients with RD had lower discontinuation treatment rates due to a reduced toxicity profile. These findings would suggest that RD BCG would compromise oncological outcomes in HR-NMIBC patients.

A keystone avian predator faces elevated energy expenditure in a warming Arctic.

Climate change is transforming bioenergetic landscapes, challenging behavioral and physiological coping mechanisms. A critical question involves whether animals can adjust behavioral patterns and energy expenditure to stabilize fitness given reconfiguration of resource bases, or whether limits to plasticity ultimately compromise energy balance. In the Arctic, rapidly warming temperatures are transforming food webs, making Arctic organisms strong models for understanding biological implications of climate change-related environmental variability. We examined plasticity in the daily energy expenditure (DEE) of an Arctic seabird, the little auk (Alle alle) in response to variability in climate change-sensitive drivers of resource availability, sea surface temperature (SST) and sea ice coverage (SIC), and tested the hypothesis that energetic ceilings and exposure to mercury, an important neurotoxin and endocrine disrupter in marine ecosystems, may limit scope for plasticity. To estimate DEE, we used accelerometer data obtained across years from two colonies exposed to distinct environmental conditions (Ukaleqarteq [UK], East Greenland; Hornsund [HS], Svalbard). We proceeded to model future changes in SST to predict energetic impacts. At UK, high flight costs linked to low SIC and high SST drove DEE from below to above 4 × basal metabolic rate (BMR), a proposed energetic threshold for breeding birds. However, DEE remained below 7 × BMR, an alternative threshold, and did not plateau. Birds at HS experienced higher, relatively invariable SST, and operated above 4 × BMR. Mercury exposure was unrelated to DEE, and fitness remained stable. Thus, plasticity in DEE currently buffers fitness, providing resiliency against climate change. Nevertheless, modeling suggests that continued warming of SST may promote accelerating increases in DEE, which may become unsustainable.

Preliminary Study of the Fresh and Hard Properties of UHPC That Is Used to Produce 3D Printed Mortar.

Three-dimensional printed concrete (3DPC) is a relatively recent technology that may be very important in changing the traditional construction industry. The principal advantages of its use are more rapid construction, lower production costs, and less residues, among others. The choice of raw materials to obtain adequate behavior is more critical than for traditional concrete. In the present paper a mixture of cement, silica fume, superplasticizer, setting accelerator, filler materials, and aggregates was studied to obtain a 3DPC with high resistance at short curing times. When the optimal mixture was found, metallic fibers were introduced to enhance the mechanical properties. The fresh and hard properties of the concrete were analyzed, measuring the setting time, workability, and flexural and compressive strength. The results obtained demonstrated that the incorporation of fibers (2% in volume) enhanced the flexural and compressive strength by around 163 and 142%, respectively, compared with the mixture without fibers, at 9 h of curing. At 28 days of curing, the improvement was 79.2 and 34.7% for flexural and compressive strength, respectively.

Will climate change affect the survival of tropical and subtropical species? Predictions based on Bulwer's petrel populations in the NE Atlantic Ocean.

Climate change has repeatedly been shown to impact the demography and survival of marine top predators. However, most evidence comes from single populations of widely distributed species, limited mainly to polar and subpolar environments. Here, we aimed to evaluate the influence of environmental conditions on the survival of a tropical and migratory seabird over the course of its annual cycle. We used capture-mark-recapture data from three populations of Bulwer's petrel (Bulweria bulwerii) spread across the NE Atlantic Ocean, from the Azores, Canary, and Cabo Verde Islands (including temperate to tropical zones). We also inferred how the survival of this seabird might be affected under different climatic scenarios, defined by the Intergovernmental Panel on Climate Change. Among the environmental variables whose effect we evaluated (North Atlantic Oscillation index, Southern Oscillation Index, Sea Surface Temperature [SST] and wind speed), SST estimated for the breeding area and season was the variable with the greatest influence on adult survival. Negative effects of SST increase emerged across the three populations, most likely through indirect trophic web interactions. Unfortunately, our study also shows that the survival of Bulwer's petrel will be profoundly affected by the different scenarios of climate change, even with the most optimistic trajectory involving the lowest greenhouse gas emission. Furthermore, for the first time, our study predicts stronger impacts of climate change on tropical populations than on subtropical and temperate ones. This result highlights the devastating effect that climate change may also have on tropical areas, and the importance of considering multi-population approaches when evaluating its impacts which may differ across species distributions.

A Study of the Flexural Behavior of Fiber-Reinforced Concretes Exposed to Moderate Temperatures.

The use of synthetic fibers in fiber-reinforced concretes (FRCs) is often avoided due to the mistrust of lower performance at changing temperatures. This work examines the effect of moderate temperatures on the flexural strengths of FRCs. Two types of polypropylene fibers were tested, and one steel fiber was employed as a reference. Three-point bending tests were carried out following an adapted methodology based on the standard EN 14651. This adapted procedure included an insulation system that allowed the assessment of FRC flexural behavior after being exposed for two months at temperatures of 5, 20, 35 and 50 °C. In addition, the interaction of temperature with a pre-cracked state was also analyzed. To do this, several specimens were pre-cracked to 0.5 mm after 28 days and conditioned in their respective temperature until testing. The findings suggest that this range of moderate temperatures did not degrade the behavior of FRCs to a great extent since the analysis of variances showed that temperature is not always a significant factor; however, it did have an influence on the pre-cracked specimens at 35 and 50 °C.

Characterization of Glass Powder from Glass Recycling Process Waste and Preliminary Testing.

This work studies the possibility of incorporating different proportions of glass powder from the waste glass (rejected material called fine cullet) produced during the glass recycling process into the manufacturing of mortar and concrete. For this purpose, the material is characterized by its chemical composition and pozzolanic activity, and the shape and size of its particles are studied. It is then incorporated as a substitute for cement into the manufacturing of mortar and concrete at 25% and 40% of cement weight, and its effect on setting times, consistency, and mechanical strength is analyzed. Its behavior as a slow pozzolan is verified, and the possibility of incorporating it into concrete is ratified by reducing its cement content and making it a more sustainable material.

Porous Structure of Ultra-High-Performance Fibre-Reinforced Concretes.

The aim of this experimental work was to study the porous structure of Ultra-High-Performance Fibre-Reinforced Concretes (UH) made with different fibre volume contents (0%, 1%, 2%) under several curing conditions (laboratory environment, 20 °C, 60 °C, 90 °C), comparing the results with those recorded for ordinary, high strength and very high strength concretes. Scanning electron microscopy, mercury intrusion porosimetry, thermogravimetry, water absorption and oxygen permeability tests were carried out. The results showed a low portlandite content in UH (in the order of 75% lower than in concrete C50) and a low degree of hydration, but they rise with curing temperature. These concretes have a very fine porous structure, with a high concentration of pores on the nanoscale level, below 0.05 µm. Their porosity accessible to water is consequently around 7-fold lower than in conventional (C30), 6-fold lower than in high-strength (C50) and 4-fold lower than in very high-strength (C90) concretes. Their oxygen permeability is at least one order of magnitude lower than in C90, two orders of magnitude lower than in C50 and three orders of magnitude lower than in C30. The percentage of added steel fibre does not affect the UH porous structure.

Global political responsibility for the conservation of albatrosses and large petrels.

Migratory marine species cross political borders and enter the high seas, where the lack of an effective global management framework for biodiversity leaves them vulnerable to threats. Here, we combine 10,108 tracks from 5775 individual birds at 87 sites with data on breeding population sizes to estimate the relative year-round importance of national jurisdictions and high seas areas for 39 species of albatrosses and large petrels. Populations from every country made extensive use of the high seas, indicating the stake each country has in the management of biodiversity in international waters. We quantified the links among national populations of these threatened seabirds and the regional fisheries management organizations (RFMOs) which regulate fishing in the high seas. This work makes explicit the relative responsibilities that each country and RFMO has for the management of shared biodiversity, providing invaluable information for the conservation and management of migratory species in the marine realm.