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The ice-covered Central Arctic Ocean is characterized by low primary productivity due to light and nutrient limitations. The recent reduction in ice cover has the potential to substantially increase phytoplankton primary production, but little is yet known about the fate of the ice-associated primary production and of the nutrient supply with increasing warming. This study presents results from the Central Arctic Ocean collected during summer 2012, when sea-ice reached a minimum extent since the onset of satellite observations. Net primary productivity (NPP) was measured in the water column, sea ice and melt ponds by 14CO2 uptake at different irradiances. Photosynthesis vs. irradiance (PI) curves were established in laboratory experiments and used to upscale measured NPP to the deep Eurasian Basin (north of 78° N) using the irradiance-based Central Arctic Ocean Primary Productivity (CAOPP) model. In addition, new annual production was calculated from the seasonal nutrient drawdown in the mixed layer since last winter. Results show that ice algae can contribute up to 60% to primary production in the Central Arctic at the end of the season. The ice-covered water column has lower NPP rates than open water due to light limitation. As indicated by the nutrient ratios in the euphotic zone, nitrate was limiting primary production in the deep Eurasian Basin close to the Laptev Sea area, while silicate was the main limiting nutrient at the ice margin near the Atlantic inflow. Although sea-ice cover was substantially reduced in 2012, total annual new production in the Eurasian Basin was 17 ± 7TgCyr-1 which is within the range of estimates of previous years. However, when adding the contribution by sub-ice algae, the annual production for the deep Eurasian Basin (north of 78° N) could double previous estimates for that area with a surplus of 16 TgCyr-1. Our data suggest that sub-ice algae are an important component of the ice-covered Central Arctic productivity. It remains an important question if their contribution to productivity is on the rise with thinning ice, or if it will decline due to overall sea-ice retreat and be replaced by phytoplankton. [ABSTRACT FROM AUTHOR]

Background : This study aimed to assess the feasibility and quality of resuscitation maneuvers performed on a newborn over the mother's body while maintaining SSC and delayed cord clamping. Methods : A randomized crossover manikin study compared standard cardiopulmonary resuscitation (Std-CPR) and cardiopulmonary resuscitation during SSC (SSC-CPR). Nursing students (n = 40) were recruited and trained in neonatal CPR. The quality of the CPR, including compression and ventilation variables, was evaluated using Laerdal Resusci Baby QCPR ® manikins. Findings : No significant differences were found in the compression variables between the Std-CPR and the SSC-CPR. The quality variables demonstrated comparable results between the two techniques. The quality of the compressions showed medians of 74% for the Std-CPR and 74% for the SSC-CPR ( p = 0.79). Similarly, the quality of the ventilations displayed medians of 94% for the Std-CPR and 96% for the SSC-CPR ( p = 0.12). The overall CPR quality exhibited medians of 75% for the Std-CPR and 82% for the SSC-CPR ( p = 0.06). Conclusions : Performing CPR on a newborn over the mother's body during SSC is feasible and does not compromise the quality of resuscitation maneuvers. This approach may offer advantages in preserving maternal-newborn bonding and optimizing newborn outcomes. Further studies are needed to address the limitations of this research, including the use of simulations that may not fully replicate real-life conditions, the lack of analysis of different types of labor, and the unpredictability of the maternal response during resuscitation.

Objective: The aim of this study was to analyze the feasibility of a new resuscitation strategy in which breaths are provided during automated external defibrillator (AED) rhythm analysis, and to evaluate its impact on chest compressions (CC) quality and the peri -analysis time., Method: A randomized simulation study, comparing two cardiopulmonary resuscitations strategies, has been conducted: the standard strategy (S1) with strategy involving ventilation during AED analysis (S2). Thirty lifeguards have performed both strategies in a cross-over study design during 10 min of CPR., Results: The number of ventilations per 10 min increases from 47 (S1) to 72 (S2) ( p  < 0.001). This results in the delivery of an additional 17.1 L of insufflated air in S2 compared to S1 ( p  < 0.001). There have been no significant changes in frequency and total number of CC. These findings correspond to a reduction of the non-ventilation period from 176 s (S1) to 48 s (S2)., Conclusions: This simulation study suggests that it is feasible to increase the number of ventilations during resuscitation following drowning, without affecting the quantity and quality of chest compressions. The results of this study may serve as a foundation for further investigation into optimal ventilation strategies in this context., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2024 The Authors.)

Enhancing ocean productivity by artificial upwelling is evaluated as a nature-based solution for food security and climate change mitigation. Fish production is intended through diatom-based plankton food webs as these are assumed to be short and efficient. However, our findings from mesocosm experiments on artificial upwelling in the oligotrophic ocean disagree with this classical food web model. Here, diatoms did not reduce trophic length and instead impaired the transfer of primary production to crustacean grazers and small pelagic fish. The diatom-driven decrease in trophic efficiency was likely mediated by changes in nutritional value for the copepod grazers. Whilst diatoms benefitted the availability of essential fatty acids, they also caused unfavorable elemental compositions via high carbon-to-nitrogen ratios (i.e. low protein content) to which the grazers were unable to adapt. This nutritional imbalance for grazers was most pronounced in systems optimized for CO 2 uptake through carbon-to-nitrogen ratios well beyond Redfield. A simultaneous enhancement of fisheries production and carbon sequestration via artificial upwelling may thus be difficult to achieve given their opposing stoichiometric constraints. Our study suggest that food quality can be more critical than quantity to maximize food web productivity during shorter-term fertilization of the oligotrophic ocean., (© 2024. The Author(s).)

(1) Objective: The objective was to evaluate the quality of cardiopulmonary resuscitation (CPR, chest compressions and ventilations) when performed by a lone first responder on an infant victim via the over-the-head technique (OTH) with bag-mask ventilation in comparison with the standard lateral technique (LAT) position. (2) Methods: A randomized simulation crossover study in a baby manikin was conducted. A total of 28 first responders performed each of the techniques in two separate CPR tests (15:2 chest compressions:ventilations ratio), each lasting 5 min with a 15 min resting period. Quality CPR parameters were assessed using an app connected to the manikin. Those variables were related to chest compressions (CC: depth, rate, and correct CC point) and ventilation (number of effective ventilations). Additional variables included perceptions of the ease of execution of CPR. (3) Results: The median global CPR quality (integrated CC + V) was 82% with OTH and 79% with LAT ( p = 0.94), whilst the CC quality was 88% with OTH and 80% with LAT ( p = 0.67), and ventilation quality was 85% with OTH and 85% with LAT ( p = 0.98). Correct chest release was significantly better with OTH (OTH: 92% vs. LAT: 62%, p < 0.001). There were no statistically significant differences in the remaining variables. Ease of execution perceptions favored the use of LAT over OTH. (4) Conclusions: Chest compressions and ventilations can be performed with similar quality in an infant manikin by lifeguards both with the standard recommended position (LAT) and the alternative OTH. This option could give some advantages in terms of optimal chest release between compressions. Our results should encourage the assessment of OTH in some selected cases and situations as when a lone rescuer is present and/or there are physical conditions that could impede the lateral rescue position.

Uncontrolled external bleeding is a common cause of preventable death, and due to the environment in which these events often occur, e.g., in hostile environments, the state security forces are usually the first responders, and in many cases, if they are injured their partners provide the initial assistance. The tourniquet is a fast, effective, and easy-to-learn intervention, although there is a knowledge gap concerning training techniques. The objective is to evaluate the effectiveness of a bleeding control training program on a high-fidelity mannequin in a simulated critical situation in a law enforcement training environment. A quasi-experimental study was carried out with 27 members of the state security forces. They underwent brief theoretical-practical training and were evaluated via a scenario involving a critically ill patient in a hostile environment. The results showed that no member of the state security forces completed all the tourniquet placement steps, 26 (96%) prepared the tourniquet correctly, 21 (77.8%) placed it on the leg, and all the participants adjusted the band to the thickness of the injured limb and secured the windlass to the triangular flange of the device. However, only 23 (85.2%) of the participants placed it effectively. The participants, who were members of the state security forces, were able to effectively resolve a critical situation with active bleeding in a simulation scenario with a high-fidelity mannequin after completing theoretical-practical training.

Background: There are few studies that analyze ventilation volume and pressure during CPR carried out on infants. The aim of this study was to evaluate the quality of the ventilations administered using a self-inflating bag with an endotracheal tube and a face mask in manikins. Methods: a quasi-experimental simulation study with a randomized case crossover design [endotracheal tube (ET) vs. face mask (FM)] was performed. Sixty participants who were previously trained nursing students participated in the study. The estimated air volumes breathed, and the pressure generated during each ventilation were assessed and the quality of the chest compressions was recorded. Results: the ET test presented a higher percentage of ventilations that reached the lungs (100% vs. 86%; p < 0.001), with adequate volume (60% vs. 28%; p < 0.001) in comparison to FM. Both tests presented peak pressures generated in the airway greater than 30 cm H2O (ET: 22% vs. FM: 31%; p = 0.03). Conclusions: performing quality CPR ventilations on an infant model is not an easy skill for trained nursing students. Both tests presented a significant incidence of excessive peak pressure during ventilations. Specific training, focused on quality of ventilations guided by a manometer attached to the self-inflating bag, must be considered in life support training for pediatric providers.

The Arctic is warming 2-3 times faster than the global average, leading to a decrease in Arctic sea ice extent, thickness, and associated changes in sea ice structure. These changes impact sea ice habitat properties and the ice-associated ecosystems. Sea-ice algal blooms provide various algal-derived carbon sources for the bacterial and archaeal communities within the sea ice. Here, we detail the transition of these communities from winter through spring to early summer during the Norwegian young sea ICE (N-ICE2015) expedition. The winter community was dominated by the archaeon Candidatus Nitrosopumilus and bacteria belonging to the Gammaproteobacteria ( Colwellia , Kangiellaceae, and Nitrinocolaceae ), indicating that nitrogen-based metabolisms, particularly ammonia oxidation to nitrite by Cand. Nitrosopumilus was prevalent. At the onset of the vernal sea-ice algae bloom, the community shifted to the dominance of Gammaproteobacteria ( Kangiellaceae, Nitrinocolaceae ) and Bacteroidia ( Polaribacter ), while Cand. Nitrosopumilus almost disappeared. The bioinformatically predicted carbohydrate-active enzymes increased during spring and summer, indicating that sea-ice algae-derived carbon sources are a strong driver of bacterial and archaeal community succession in Arctic sea ice during the change of seasons. This implies a succession from a nitrogen metabolism-based winter community to an algal-derived carbon metabolism-based spring/ summer community.

The use of personal protective equipment (PPE) is required for the self-protection of healthcare workers during cardiopulmonary resuscitation (CPR) in patients at risk of aerosol transmission of infectious agents. The aim of this study was to analyze the impact of personal protective equipment on physiological parameters during CPR. A randomized, quasi-experimental, crossover design was used. The study was carried out in a training and simulation emergency box and the total sample consisted of 20 healthcare professionals. Two CPR tests were compared with the recommended sequence of 30 chest compressions and 2 ventilations. The duration of each test was 20 min. One of the CPR tests was carried out without using any PPE (CPR&#95;control), i.e., performed with the usual clothing of each rescuer. The other test was carried out using a CPR test with PPE (i.e., CPR&#95;PPE). The main variables of interest were: CPR quality, compressions, ventilations, maximum heart rate, body fluid loss, body temperature, perceived exertion index, comfort, thermal sensation and sweating. The quality of the CPR was similar in both tests. The maximum heart rate was higher in the active intervals (compressions + bag-valve-mask) of the test with PPE. CPR&#95;PPE meant an increase in the perceived effort, temperature at the start of the thermal sensation test, thermal comfort and sweating, as opposed to CPR performed with usual clothing. Performing prolonged resuscitation with PPE did not influence CPR quality, but caused significant physiological demands. Rescuers were more fatigued, sweated more and their thermal comfort was worse. These results suggest that physical preparation should be taken into account when using PPE and protocols for physiological recovery after use should also be established.

Objective: To assess the differences in the quality and self-perception of CPR performed with foot technique compared to the standard technique with the hands in nursing students., Methods: 65 university nursing students participated in a randomized simulation crossover design study. The participants randomly performed two CPR tests: CPR by foot and CPR by hands techniques. The compression-only protocol with a 2-min test was used with the Resusci Anne QCPR® manikin and Wireless Skill Reporter® software, both from Laerdal., Results: Participants had lower quality when doing CPR by foot (72%) than when doing standard CPR (91%) (p = 0.006). 95% of the participants indicated standard CPR as the technique of choice, while 92% indicated that they would use CPR by foot if it was not possible to perform standard technique., Conclusions: CPR quality was lower when performing foot technique, although with positive results. It would be advisable for people with acquired CPR skills to know that they can do foot compressions in situations where they cannot use their hands., Competing Interests: Declaration of Competing Interest None., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Aim: To analyse the effect of oxygen fraction reduction (O2 14%, equivalent to 3250 m) on Q-CPR and rescuers' physiological demands., Methodology: A quasi-experimental study was carried out in a sample of 9 Q-CPR proficient health care professionals. Participants, in teams of 2 people, performed 10 min CPR on a Laerdal ResusciAnne mannequin (30:2 compression/ventilation ratio and alternating roles between rescuers every 2 min) in two simulated settings: T21-CPR at sea level (FiO2 of 21%) and T14 - CPR at 3250 m altitude (FiO2 of 14%). Effort self-perception was rated from 0 (no effort) to 10 (maximum demand) points., Results: Quality of chest compressions was good and similar in both conditions (T21 vs T14). However, the percentage of ventilations with adequate tidal volume was lower in altitude than at sea level conditions (35.9 ± 25.2% vs. 54.7 ± 23.2%, p = 0.035). The subjective perception of effort was significantly higher at simulated altitude (5 ± 2) than at sea level (3 ± 2) (p = 0.038). Maximum heart rate during the tests was similar in both conditions; however, mean oxygen saturation was significantly lower in altitude conditions (90.5 ± 2.5% vs. 99.3 ± 0.5%, p < 0.001)., Conclusion: Although performing CPR under simulated hypoxic altitude conditions significantly increases the physiological demands and subjective feeling of tiredness compared to sea level CPR, trained rescuers are able to deliver good Q-CPR in such conditions, at least in the first 10 min of resuscitation., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Objective: Lifeguard teams carry out their work in extremely hot conditions in many parts of the world. The aim of this study was to analyze the impact of high temperatures on physiological parameters during cardiopulmonary resuscitation (CPR)., Method: A randomized quasi-experimental cross-over design was used to test physiological lifesaving demands (50 min acclimatization +10 min CPR) in two different thermal environments: Thermo-neutral environment (25 °C) vs Hyperthermic environment (37 °C)., Results: The data obtained from 21 lifeguards were included, this covers a total of 420 min of resuscitation. The CPR performance was constantly maintained during the 10 min. The Oxygen uptake (VO 2) ranged from 17 to 18 ml/min/kg for chest compressions (CC) and between 13 and 14 ml/min/kg for ventilations (V) at both 25 °C and 37 °C, with no significant difference between environments (p > 0.05). The percentage of maximum heart rate (%HR max) increased between 7% and 8% at 37 °C (p < 0.001), ranging between 75% and 82% of HR max. The loss of body fluids (LBF) was higher in the hyperthermic environment; LBF: (37 °C: 400 ± 187 g vs 25 °C: 148 ± 81 g, p < 0.001). Body temperature was 1 °C higher at the end of the test (p < 0.001). The perceived fatigue (RPE) increased by 37° an average of 2 points on a scale of 10 (p = 0.001)., Conclusions: Extreme heat is not a limiting factor in CPR performance with two lifeguards. Metabolic consumption is sustained, with an increase in CC, so V can serve as active rest. Nevertheless, resuscitation at 37 °C results in a higher HR, is more exhausting and causes significant loss of fluids due to sweating., (Copyright © 2020 Elsevier Inc. All rights reserved.)

One of the most prominent manifestations of climate change is the changing Arctic sea-ice regime with a reduction in the summer sea-ice extent and a shift from thicker, perennial multiyear ice towards thinner, first-year ice. These changes in the physical environment are likely to impact microbial communities, a key component of Arctic marine food webs and biogeochemical cycles. During the Norwegian young sea ICE expedition (N-ICE2015) north of Svalbard, seawater samples were collected at the surface (5 m), subsurface (20 or 50 m), and mesopelagic (250 m) depths on 9 March, 27 April, and 16 June 2015. In addition, several physical and biogeochemical data were recorded to contextualize the collected microbial communities. Through the massively parallel sequencing of the small subunit ribosomal RNA amplicon and metagenomic data, this work allows studying the Arctic's microbial community structure during the late winter to early summer transition. Results showed that, at compositional level, Alpha- (30.7%) and Gammaproteobacteria (28.6%) are the most frequent taxa across the prokaryotic N-ICE2015 collection, and also the most phylogenetically diverse. Winter to early summer trends were quite evident since there was a high relative abundance of thaumarchaeotes in the under-ice water column in late winter while this group was nearly absent during early summer. Moreover, the emergence of Flavobacteria and the SAR92 clade in early summer might be associated with the degradation of a spring bloom of Phaeocystis. High relative abundance of hydrocarbonoclastic bacteria, particularly Alcanivorax (54.3%) and Marinobacter (6.3%), was also found. Richness showed different patterns along the depth gradient for prokaryotic (highest at mesopelagic depth) and protistan communities (higher at subsurface depths). The microbial N-ICE2015 collection analyzed in the present study provides comprehensive new knowledge about the pelagic microbiota below drifting Arctic sea-ice. The higher microbial diversity found in late winter/early spring communities reinforces the need to continue with further studies to properly characterize the winter microbial communities under the pack-ice.

In the Arctic Ocean ice algae constitute a key ecosystem component and the ice algal spring bloom a critical event in the annual production cycle. The bulk of ice algal biomass is usually found in the bottom few cm of the sea ice and dominated by pennate diatoms attached to the ice matrix. Here we report a red tide of the phototrophic ciliate Mesodinium rubrum located at the ice-water interface of newly formed pack ice of the high Arctic in early spring. These planktonic ciliates are not able to attach to the ice. Based on observations and theory of fluid dynamics, we propose that convection caused by brine rejection in growing sea ice enabled M. rubrum to bloom at the ice-water interface despite the relative flow between water and ice. We argue that red tides of M. rubrum are more likely to occur under the thinning Arctic sea ice regime.

Left atrium (LA) size has an important role in determining prognosis and risk stratification in hypertrophic cardiomyopathy (HCM). Cardiovascular magnetic resonance myocardial feature tracking (CMR-FT) is a novel technique for the quantification of LA function. Our aim was first to evaluate LA function by CMR-FT and volumetric analysis in patients with HCM; and secondly we sought to determine the association of LA-longitudinal strain (LA-LS) with major cardiovascular outcomes, particularly all cause mortality and heart failure. 75 patients with HCM and 75 control subjects underwent a conventional CMR study including assessment of LA function by CMR-FT (LA-LS) and volumetric analysis. A primary endpoint of all-cause mortality and secondary combined endpoint of hospital admission related to heart failure, lethal ventricular arrhythmias or cardiovascular death were defined. Compared to controls, LA-LS and all volumetric indices of LA function were significantly impaired in HCM even in patients with normal LA volume and normal LV filling pressures. LA-LS showed moderate-high correlation with LA-emptying fraction (total, active and passive LA-EF, r = 0.68, r = 0.67, r = 0.31, p < 0.001 for all) and with parameters of diastolic function (E/é, r = 0.4, p < 0.001). The age, minimum LA volume and % of LGE were independent predictors of LA-LS (p < 0.01 for all). During a mean follow-up of 3.3 ± 1.2 years LA-LS was associated with the primary (HR: 0.85 (0.73-0.98), p = 0.02) and the secondary end-point (HR: 0.88 (0.82-0.96), p = 0.003). LA-LS by CMR-FT provides accurate measurements of LA function in HCM patients. LA-LS may become a novel potential predictor of poor cardiac outcomes, particularly cardiovascular mortality and HF.

In summer 2012, Arctic sea ice declined to a record minimum and, as a consequence of the melting, large amounts of aggregated ice-algae sank to the seafloor at more than 4,000 m depth. In this study, we assessed the composition, turnover and connectivity of bacterial and microbial eukaryotic communities across Arctic habitats from sea ice, algal aggregates and surface waters to the seafloor. Eukaryotic communities were dominated by diatoms, dinoflagellates and other alveolates in all samples, and showed highest richness and diversity in sea-ice habitats (∼400-500 OTUs). Flavobacteriia and Gammaproteobacteria were the predominant bacterial classes across all investigated Arctic habitats. Bacterial community richness and diversity peaked in deep-sea samples (∼1,700 OTUs). Algal aggregate-associated bacterial communities were mainly recruited from the sea-ice community, and were transported to the seafloor with the sinking ice algae. The algal deposits at the seafloor had a unique community structure, with some shared sequences with both the original sea-ice community (22% OTU overlap), as well as with the deep-sea sediment community (17% OTU overlap). We conclude that ice-algal aggregate export does not only affect carbon export from the surface to the seafloor, but may change microbial community composition in central Arctic habitats with potential effects for benthic ecosystem functioning in the future.

Solar panels located on high (Arctic and Antarctic) latitudes combine the harshness of the climate with that of the solar exposure. We report here that these polar solar panels are inhabited by similar microbial communities in taxonomic terms, dominated by Hymenobacter spp., Sphingomonas spp. and Ascomycota. Our results suggest that solar panels, even on high latitudes, can shape a microbial ecosystem adapted to irradiation and desiccation., (© 2017 Society for Applied Microbiology and John Wiley & Sons Ltd.)

Purpose: The aim of this study is to compare the effectiveness of active recovery in form of running or foam rolling on clearing blood lactate compared to remain sitting after a water rescue., Method: A quasi experimental cross-over design was used to test the effectiveness of two active recovery methods: foam rolling (FR) and running (RR), compared with passive recovery (PR) on the blood lactate clearance after performing a water rescue. Twelve lifeguards from Marín (Pontevedra) completed the study. The participants performed a 100-meter water rescue and a 25-minute recovery protocol., Results: The post recovery lactate levels were significantly lower for foam rolling (4.4±1.5mmol/l, P=0.005, d=0.94) and running (4.9±2.3mmol/l, P=0.027, d=1.21) compared with resting (7.2±2.5mmol/l); there was no significant difference between foam rolling and running (P=1.000)., Conclusions: We found that surf lifesavers clear out blood lactate more efficient when performing an active recovery protocol. Foam rolling is an effective method of increasing the rate of blood lactate clearance. These two recovery methods are also adequate for surf lifeguards as they do not interfere with the surveillance aspect of their job., (Copyright © 2017 Elsevier Inc. All rights reserved.)

The Arctic icescape is rapidly transforming from a thicker multiyear ice cover to a thinner and largely seasonal first-year ice cover with significant consequences for Arctic primary production. One critical challenge is to understand how productivity will change within the next decades. Recent studies have reported extensive phytoplankton blooms beneath ponded sea ice during summer, indicating that satellite-based Arctic annual primary production estimates may be significantly underestimated. Here we present a unique time-series of a phytoplankton spring bloom observed beneath snow-covered Arctic pack ice. The bloom, dominated by the haptophyte algae Phaeocystis pouchetii, caused near depletion of the surface nitrate inventory and a decline in dissolved inorganic carbon by 16 ± 6 g C m -2 . Ocean circulation characteristics in the area indicated that the bloom developed in situ despite the snow-covered sea ice. Leads in the dynamic ice cover provided added sunlight necessary to initiate and sustain the bloom. Phytoplankton blooms beneath snow-covered ice might become more common and widespread in the future Arctic Ocean with frequent lead formation due to thinner and more dynamic sea ice despite projected increases in high-Arctic snowfall. This could alter productivity, marine food webs and carbon sequestration in the Arctic Ocean.

The Eurasian basin of the Central Arctic Ocean is nitrogen limited, but little is known about the presence and role of nitrogen-fixing bacteria. Recent studies have indicated the occurrence of diazotrophs in Arctic coastal waters potentially of riverine origin. Here, we investigated the presence of diazotrophs in ice and surface waters of the Central Arctic Ocean in the summer of 2012. We identified diverse communities of putative diazotrophs through targeted analysis of the nifH gene, which encodes the iron protein of the nitrogenase enzyme. We amplified 529 nifH sequences from 26 samples of Arctic melt ponds, sea ice and surface waters. These sequences resolved into 43 clusters at 92% amino acid sequence identity, most of which were non-cyanobacterial phylotypes from sea ice and water samples. One cyanobacterial phylotype related to Nodularia sp. was retrieved from sea ice, suggesting that this important functional group is rare in the Central Arctic Ocean. The diazotrophic community in sea-ice environments appear distinct from other cold-adapted diazotrophic communities, such as those present in the coastal Canadian Arctic, the Arctic tundra and glacial Antarctic lakes. Molecular fingerprinting of nifH and the intergenic spacer region of the rRNA operon revealed differences between the communities from river-influenced Laptev Sea waters and those from ice-related environments pointing toward a marine origin for sea-ice diazotrophs. Our results provide the first record of diazotrophs in the Central Arctic and suggest that microbial nitrogen fixation may occur north of 77°N. To assess the significance of nitrogen fixation for the nitrogen budget of the Arctic Ocean and to identify the active nitrogen fixers, further biogeochemical and molecular biological studies are needed.

We investigated 32 net primary productivity (NPP) models by assessing skills to reproduce integrated NPP in the Arctic Ocean. The models were provided with two sources each of surface chlorophyll- a concentration (chlorophyll), photosynthetically available radiation (PAR), sea surface temperature (SST), and mixed-layer depth (MLD). The models were most sensitive to uncertainties in surface chlorophyll, generally performing better with in situ chlorophyll than with satellite-derived values. They were much less sensitive to uncertainties in PAR, SST, and MLD, possibly due to relatively narrow ranges of input data and/or relatively little difference between input data sources. Regardless of type or complexity, most of the models were not able to fully reproduce the variability of in situ NPP, whereas some of them exhibited almost no bias (i.e., reproduced the mean of in situ NPP). The models performed relatively well in low-productivity seasons as well as in sea ice-covered/deep-water regions. Depth-resolved models correlated more with in situ NPP than other model types, but had a greater tendency to overestimate mean NPP whereas absorption-based models exhibited the lowest bias associated with weaker correlation. The models performed better when a subsurface chlorophyll- a maximum (SCM) was absent. As a group, the models overestimated mean NPP, however this was partly offset by some models underestimating NPP when a SCM was present. Our study suggests that NPP models need to be carefully tuned for the Arctic Ocean because most of the models performing relatively well were those that used Arctic-relevant parameters.

The sea ice cover of the Arctic Ocean has changed dramatically in the last decades, and the resulting consequences for the sea-ice-associated ecosystem remain difficult to assess. Algal aggregates underneath sea ice are of great importance for the ice-associated ecosystem and the pelagic-benthic coupling. However, the frequency and distribution of their occurrence is not well quantified. During the IceArc expedition (ARK-27/3) of RV Polarstern in late summer 2012, we observed different types of algal aggregates floating underneath various ice types in the Central Arctic basins. We investigated the spatial distribution of ice algal aggregates and quantified their biomass, using under-ice image surveys obtained by an upward-looking camera on a remotely operated vehicle. On basin scale, filamentous aggregates of Melosira arctica are more frequently found in the inner part of the Central Arctic pack ice, while rounded aggregates mainly formed by pennate diatoms are found closer to the ice edge, under melting sea ice. On the scale of an ice floe, the distribution of algal aggregates in late summer is mainly regulated by the topography of the ice underside, with aggregates accumulating in dome-shaped structures and at the edges of pressure ridges. The average biomass of the aggregates from our sites and season was 0.1-6.0 mg C m -2 . However, depending on the approach used, differences in orders of magnitude for biomass estimates may occur. This highlights the difficulties of upscaling observations and comparing results from surveys conducted using different methods or on different spatial scales.

Sea-ice diatoms are known to accumulate in large aggregates in and under sea ice and in melt ponds. There is recent evidence from the Arctic that such aggregates can contribute substantially to particle export when sinking from the ice. The role and regulation of microbial aggregation in the highly seasonal, nutrient- and light-limited Arctic sea-ice ecosystem is not well understood. To elucidate the mechanisms controlling the formation and export of algal aggregates from sea ice, we investigated samples taken in late summer 2011 and 2012, during two cruises to the Eurasian Basin of the Central Arctic Ocean. Spherical aggregates densely packed with pennate diatoms, as well as filamentous aggregates formed by Melosira arctica showed sign of different stages of degradation and physiological stoichiometries, with carbon to chlorophyll a ratios ranging from 110 to 66700, and carbon to nitrogen molar ratios of 8-35 and 9-40, respectively. Sub-ice algal aggregate densities ranged between 1 and 17 aggregates m(-2), maintaining an estimated net primary production of 0.4-40 mg C m(-2) d(-1), and accounted for 3-80% of total phototrophic biomass and up to 94% of local net primary production. A potential factor controlling the buoyancy of the aggregates was light intensity, regulating photosynthetic oxygen production and the amount of gas bubbles trapped within the mucous matrix, even at low ambient nutrient concentrations. Our data-set was used to evaluate the distribution and importance of Arctic algal aggregates as carbon source for pelagic and benthic communities.

During two consecutive cruises to the Eastern Central Arctic in late summer 2012, we observed floating algal aggregates in the melt-water layer below and between melting ice floes of first-year pack ice. The macroscopic (1-15 cm in diameter) aggregates had a mucous consistency and were dominated by typical ice-associated pennate diatoms embedded within the mucous matrix. Aggregates maintained buoyancy and accumulated just above a strong pycnocline that separated meltwater and seawater layers. We were able, for the first time, to obtain quantitative abundance and biomass estimates of these aggregates. Although their biomass and production on a square metre basis was small compared to ice-algal blooms, the floating ice-algal aggregates supported high levels of biological activity on the scale of the individual aggregate. In addition they constituted a food source for the ice-associated fauna as revealed by pigments indicative of zooplankton grazing, high abundance of naked ciliates, and ice amphipods associated with them. During the Arctic melt season, these floating aggregates likely play an important ecological role in an otherwise impoverished near-surface sea ice environment. Our findings provide important observations and measurements of a unique aggregate-based habitat during the 2012 record sea ice minimum year.

In the Arctic, under-ice primary production is limited to summer months and is restricted not only by ice thickness and snow cover but also by the stratification of the water column, which constrains nutrient supply for algal growth. Research Vessel Polarstern visited the ice-covered eastern-central basins between 82° to 89°N and 30° to 130°E in summer 2012, when Arctic sea ice declined to a record minimum. During this cruise, we observed a widespread deposition of ice algal biomass of on average 9 grams of carbon per square meter to the deep-sea floor of the central Arctic basins. Data from this cruise will contribute to assessing the effect of current climate change on Arctic productivity, biodiversity, and ecological function.

Objective: 1) To determine the number of clinic visits in primary care due to musculoskeletal pain in children > or = 3 years. 2) To describe the demographic characteristics of the population assessed for limb/back pain. 3) To characterize the etiology of musculoskeletal pain in a general pediatric clinic., Patients and Methods: A prospective lineal study was performed between October 30, 1996 and January 14, 1997 in two urban general pediatric clinics located in the city of Madrid (Spain). During the period of the study, all consultations related to musculoskeletal pain were registered in a protocol form. In addition, a registry of all clinic visits was maintained during the study., Results: During the study period, 43 clinic visits were due to musculoskeletal pain, representing 6.2% (43/692) of the clinic visits in children > or = 3 years of age (95% confidence interval 4.4-7.9%). The mean age was 9.8 years (+/- 3.2 years). These complaints, although statistically non-significant, were more frequent in children > or = 10 years old (53.4%) and in males (65.1%). The most frequent complaints were knee athralgias (30%), arthralgias of other joints (23%) and soft tissue pain (18%). These symptoms were usually due to overuse syndromes and normal skeletal growth variants., Conclusions: The increase of primary pediatric care age from 7 to 14 years of age is associated with an increase in the number of consultations related to musculoskeletal pain. This information should be kept in mind at the time of designing continuing medical education and training programs in pediatrics.

With the aim of finding a correlation between the blocking of G.H. secretion and the irregularities in the permeability of the hematoretinal barrier, we have studied the average nocturnal G.H. levels (NAGHL) and the vitreous penetration rate (VPR) in five young diabetic patients. These patients, 3 males and 2 females, were between the ages of 12 and 17 years with a mean age of 16.0. They were studies both before and after receiving treatment for one month with an oral nocturnal dose of 0.6 mg/kg of pirenzepine (gastrozepin) and 1 mg/kg during the subsequent five months. We also tried to find a relationship between the VPR post-treatment and the evolution time of their illness and with their BA1C. The most important results found in this study were: 1) the nocturnal oral pirenzepine modified the NAGHL in the study population (10.48 +/- 4.94 vs; 4.34 +/- 2.53 ng/ml; p < 0.05). 2) Ingestion of the aforementioned drug did not affect the VPR (4.84 +/- 2.08 vs 4.53 +/- 2.54 x 10(-6)/min; p > 0.05). We have not found a relationship between the VPR after treatment with either the HBA1C levels or with the evolution time of the illness. Therefore, we conclude that the dose of oral pirenzepine used for 6 months, although it definitely decreases G.H. secretion, does not modify the permeability of the B.H.R. within this group of young diabetics. Hence, we can infer that the G.H. hypersecretion does not seem to have a relationship, at least exclusively, with the development of diabetic retinopathy.

Previous studies have demonstrated an elevation in GH in adult insulin-dependent diabetics which can be modified by administration of pirenzepina either IV or orally. In this study we have evaluated the mean nocturnal GH levels (MNGH) and HbA1-C levels in a group of young insulin-dependent diabetics, both before and after treatment with pirenzepina (Gastrozepin). The study population included 8 patients, 6 males and 2 females, between the ages of 12 and 17 years, with a mean of 15.6 years. Pirenzepina was administered during one month at a nightly oral dose of 0.6 mg/kg followed by 5 months of treatment with 1 mg/kg. The most important results obtained in the study are the following: 1) Nocturnal administration of pirenzepina did not significantly modify the MNGH in the study population (10.88 +/- 3.81 ng/ml vs 9.57 +/- 8.25 ng/ml, p > 0.05). 2) This pharmaceutical did not alter the plasma levels of HbA1-C (9.57 +/- 8.25 vs 10.01 +/- 2.30, p > 0.05). However, 5 out of 8 patients had a decrease in their nocturnal GH secretion after pirenzepina treatment. If only the 5 patients that responded to this treatment are considered, the differences in MNGH are significant (10.48 +/- 4.94 before treatment vs 4.35 +/- 2.53 following treatment, p < 0.05). Therefore, we conclude that oral pirenzepina treatment for 6 months, at the doses described, do not consistently decrease GH secretion in young diabetics nor does it decrease HbA1-C values in this group. However, further studies are necessary to establish the possible value of this treatment.