| 1. |
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| 2. |
- Abrahamsson, Thomas R, 1968-, et al.
(författare)
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Probiotics in prevention of IgE-associated eczema : a double-blind, randomized, placebo-controlled trial
- 2007
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Ingår i: Journal of Allergy and Clinical Immunology. - : Elsevier BV. - 0091-6749 .- 1097-6825. ; 119:5, s. 1174-1180
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: An altered microbial exposure may underlie the increase of allergic diseases in affluent societies. Probiotics may alleviate and even prevent eczema in infants. OBJECTIVE: To prevent eczema and sensitization in infants with a family history of allergic disease by oral supplementation with the probiotic Lactobacillus reuteri. METHODS: Double-blind, randomized, placebo-controlled trial, which comprised 232 families with allergic disease, of whom 188 completed the study. The mothers received L reuteri ATCC 55730 (1 x 10(8) colony forming units) daily from gestational week 36 until delivery. Their babies then continued with the same product from birth until 12 months of age and were followed up for another year. Primary outcome was allergic disease, with or without positive skin prick test or circulating IgE to food allergens. RESULTS: The cumulative incidence of eczema was similar, 36% in the treated versus 34% in the placebo group. The L reuteri group had less IgE-associated eczema during the second year, 8% versus 20% (P = .02), however. Skin prick test reactivity was also less common in the treated than in the placebo group, significantly so for infants with mothers with allergies, 14% versus 31% (P = .02). Wheeze and other potentially allergic diseases were not affected. CONCLUSION: Although a preventive effect of probiotics on infant eczema was not confirmed, the treated infants had less IgE-associated eczema at 2 years of age and therefore possibly run a reduced risk to develop later respiratory allergic disease. CLINICAL IMPLICATION: Probiotics may reduce the incidence of IgE-associated eczema in infancy.
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| 3. |
- Albin, Maria, et al.
(författare)
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Delegation med viktigt uppdrag
- 2009
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Ingår i: Bulletin från Arbets- och miljömedicin Syd och Yrkes- och miljödermatologi, Malmö. - 2000-3633.
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Tidskriftsartikel (populärvet., debatt m.m.)
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| 4. |
- Albin, Maria, et al.
(författare)
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Occupational health epidemiology in the Nordic countries – status and trends
- 2009
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Ingår i: Scandinavian Joural of Work, Environment and Health, supplements. - 1795-9918. ; suppl:7, s. 7-41
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Tidskriftsartikel (refereegranskat)abstract
- This overview aims to give an indication of the current status and trends in occupational health epidemiology in the Nordic countries. As indicated by recent biometric reviews, Nordic countries currently rank among the top five globally in terms of research output on the work environment. However, birth-cohort effects and rapid change in institutions and funding may seriously jeopardize this position. As a result, training a new generation of excellent researchers will be a major task for the next decade and require changes in funding structures. With respect to research topics, the ageing population in the Nordic countries will make preservation of work ability a major issue to explore from a multidisciplinary perspective. Moreover, the growing migration of labor, goods, and capital across borders is likely to increase the number of workers involved in dangerous work and unprotected by minimal occupational safety measures. Consequently, there is a need to research the efficiency of the present occupational safety structures under these new conditions. Research on occupational health services remains remarkably scant. The increase of mental ill-health, especially among young women, and the related interaction between structural societal change and the work environment are important challenges. New suggested disease mechanisms (eg, epigenetic change, oxidative stress, and intrauterine priming of sensitivity to postnatal exposure) are also important applied research areas for occupational epidemiology.
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| 5. |
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| 6. |
- Anderson, Craig, 1976, et al.
(författare)
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Autoradiographic comparisons of radionuclide adsorption between subsurface anaerobic biofilms and granitic host rocks
- 2006
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Ingår i: Geomicrobiology Journal. - : Informa UK Limited. - 0149-0451 .- 1521-0529. ; 23:1, s. 15-29
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Tidskriftsartikel (refereegranskat)abstract
- In high level nuclear waste repositories, the host rock is considered to be an important barrier to radionuclide migration by adsorbing metals at fluid rock interfaces. In granitic rock environments the surfaces of hydraulically conductive fractures are covered with mixed community biofilms. Biofilms were grown in situ on glass and rock surfaces in high pressure flow cells using groundwater sourced from a borehole 450 meters below sea level in the Aspo hard rock laboratory, Sweden. Scanning electron microscopy (SEM), epifluorescence microscopy and energy dispersive X-Ray spectroscopy (EDS) revealed monolayer biofilms consisting of up to 2 x 10(4) bacteria/mm(2) surrounded by an extensive extracellular matrix and carbonate precipitates that covered
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| 7. |
- Anderson, Craig, 1976, et al.
(författare)
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Influence of in situ biofilm coverage on the radionuclide adsorption capacity of subsurface granite
- 2007
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Ingår i: Environmental Science & Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 41:3, s. 830-836
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Tidskriftsartikel (refereegranskat)abstract
- Any migration of radionuclides from nuclear waste repositories is expected to be mitigated by adsorption to the host rocks surrounding hydraulically conductive fractures. Fluid rock interfaces are considered to be important barriers for nuclear waste disposal schemes but their adsorptive capacity can be affected by the growth of microbial biofilms. This study indicates that biofilms growing on fracture surfaces decrease the rocks adsorption capacity for migrating radionuclides except for trivalent species. Potential suppression of adsorption by biofilms should, therefore, be accounted for in performance safety assessment models. In this study, the adsorptive capacity of in situ anaerobic biofilms grown 450 m underground on either glass or granite slides was compared to the capacity of the same surfaces without biofilms. Surfaces were exposed to the radiotracers Co-60(II), Pm-147(III), Am-241(III), Th-234(IV), and Np-237(V) for a period of 660 h in a pH neutral anaerobic synthetic groundwater. Adsorption was investigated at multiple time points over the 660 h using liquid scintillation and ICP-MS. Results indicate that these surfaces adsorb between 0 and 85% of the added tracers under the conditions of the specific experiments. After 660 h, the distribution coefficients, R (ratio between what is sorbed and what is left in the aqueous phase), approached 3 x 10(4) m for Co-60, 3 x 10(5) m for Pm-147 and 24 'Am, I x 106 m for 234Th, and 1 x 103 m for 237Np. The highest rate of adsorption was during the first 200 h of the adsorption experiments and started to approach equilibrium after 500 h. Adsorption to colloids and precipitates contributed to decreases of up to 20% in the available Co-60, Pm-147, Am-241, and Np-237 in the adsorption systems. In the 234Th system 95% of the aqueous 234Th was removed by adsorbing to colloids. Although the range of R values for each surface tested generally overlapped, the biofilms consistently demonstrated lower R values except for the trivalant Pm-147 and Am-241 adsorption systems.
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| 8. |
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| 9. |
- Athanasiadou, Maria, et al.
(författare)
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Polybrominated diphenyl ethers (PBDEs) and bioaccumulative hydroxylated PBDE metabolites in young humans from Managua, Nicaragua.
- 2008
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Ingår i: Environ Health Perspect. - : Environmental Health Perspectives. - 0091-6765 .- 1552-9924. ; 116:3, s. 400-8
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: Our aim was to investigate exposure to polybrominated diphenyl ethers (PBDEs) in a young urban population in a developing country, with focus on potentially highly exposed children working informally as scrap scavengers at a large municipal waste disposal site. We also set out to investigate whether hydroxylated metabolites, which not hitherto have been found retained in humans, could be detected. METHODS: We assessed PBDEs in pooled serum samples obtained in 2002 from children 11-15 years of age, working and sometimes also living at the municipal waste disposal site in Managua, and in nonworking urban children. The influence of fish consumption was evaluated in the children and in groups of women 15-44 years of age who differed markedly in their fish consumption. Hydroxylated PBDEs were assessed as their methoxylated derivates. The chemical analyses were performed by gas chromatography/mass spectrometry, using authentic reference substances. RESULTS: The children living and working at the waste disposal site showed very high levels of medium brominated diphenyl ethers. The levels observed in the referent children were comparable to contemporary observations in the United States. The exposure pattern was consistent with dust being the dominating source. The children with the highest PBDE levels also had the highest levels of hydroxylated metabolites. CONCLUSIONS: Unexpectedly, very high levels of PBDEs were found in children from an urban area in a developing country. Also, for the first time, hydroxylated PBDE metabolites were found to bioaccumulate in human serum.
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| 10. |
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| 11. |
- Bergman, Mats, 1964-, et al.
(författare)
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An econometric analysis of the european commission’s merger decisions
- 2005
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Ingår i: International Journal of Industrial Organization. - : Elsevier. - 0167-7187 .- 1873-7986. ; 23:9/10, s. 717-737
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Tidskriftsartikel (refereegranskat)abstract
- Using a sample of 96 mergers notified to the European Commission and logit regression techniques, we analyse the Commission's decision process. We find that the probability of a phase-2 investigation and of a prohibition of the merger increases with the parties' market shares. The probabilities increase also when the Commission finds high entry barriers or that the post-merger market structure is conducive to collusion. We do not find significant effects of “political” variables, such as the nationality of the merging firm.
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| 12. |
- Cuadra, Steven, et al.
(författare)
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Persistent organochlorine pollutants in children working at a waste-disposal site and in young females with high fish consumption in Managua, Nicaragua
- 2006
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Ingår i: Ambio. - 0044-7447 .- 1654-7209. ; 35:3, s. 109-116
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to assess persistent organochlorine pollutant (POP) levels in serum collected from children (11-15 years old) working and sometimes also living at the municipal waste-disposal site in Managua, located at the shore of Lake Managua, and in nonworking children living both nearby and also far away from the waste-disposal site. The influence of fish consumption was further evaluated by assessing POPS levels in serum from young women (15-24 years old) with markedly different patterns of fish consumption from Lake Managua. 2,2-bis(4-chlorophenyl)-1,1,1-trichloro-ethane (4,4’-DDT) and 2,2-bis(4-chlorophenyl)-1,1-dichloro-ethene (4,4-DDE), T-hexachlorocyclohexane (gamma-HCH), polychlorinated biphenyls, pentachlorophenol, and polychlorobiphenylols were quantified in all samples. In general, the levels observed were higher than those reported in children from developed countries, such as Germany and United States. Toxaphene, aldrin, dieldrin, and beta-HCH could not be identified in any sample. The children working at the waste-disposal site had higher levels of POPS compared with the nonworking reference groups. In children not working, there were also gradients for several POPs, according to vicinity to the waste-disposal site. Moreover, in children, as well as in young women, there were gradients according to fish consumption. The most abundant component was 4,4-DDE, but at levels still lower than those reported in children from malarious areas with a history of recent or current application of 4,4-DDT for vector control.
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| 13. |
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| 14. |
- Fregidou-Malama, Maria, 1944-, et al.
(författare)
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Etablering av regional yrkeshögskoleutbildning i Hofors och Sandviken
- 2008
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Denna utvärdering behandlar projektet Etablering av två yrkeshögskoleutbildningar i Hofors och Sandviken. Syftet med utvärderingen är att studera projektmedlemmarnas inställning till etablering av programmen. Utvärderingen bygger på intervjuer och fokusgruppdiskussioner med intressenter inom projektet såväl som inlämnat självutvärderingar och annat material. År 2003 påbörjades ett projekt på Högskolan i Gävle (HiG) för att omvandla två Kvalificerade Yrkesutbildningar (KY) till YrkesHögskoleutbildningar (YH). Information om hur YH-utbildningar bör etableras, planering, resurssökning för projektet och marknadsföring av programmen uträttades därför med stor hast, för att utbildningarna skulle kunna fortgå och ej behöva ligga nere under omformningstiden. Resultatet visar att Serie- och Bildprogrammet är väl etablerat, och trots den snabba starten ej hade några allvarliga problem med studentrekrytering. Avståndet till HiG och en diffus ansvarsbild, samt lärarlagsförändringar har dock skapat arbetsbörda och problem i utbildning och supportverksamhet. När det gäller Internetteknologiprogrammet verkar detta fungerat väl, även om den snabba omvandlingen ledde till en låg rekryteringsnivå under första verksamhetsåret. Det har varit problem med lärarlagets uppbyggnad och stabilitet, vilket tillsammans med kulturskillnader mellan programmets och HiGs lärare har gjort att målsättningen att implementera problembaserat lärande ej uppnåtts i önskad grad. Då vissa kostnader redovisades sent och var högre än förväntat gick denna del av projektet över budget. Vår studie visar att även om vissa problem uppstått på vägen är projektet väl genomfört, utvärderat enligt målen att YH-utbildningarna skulle vara väl etablerade; förbereda för uppdragsutbildningsverksamhet; samt att utveckla ett kontaktnät med näringslivet för de båda programmen. Dock har ingen uppdragsutbildningsverksamhet kunnat genomföras men detta har bedömts ej vara en lämplig målsättning i detta tidiga skede. För IT-teknologiprogrammet finns möjligheter att utveckla sådan verksamhet som ett framtida projekt, men den regionala marknaden för Serie & Bildprogrammet anses vara mindre lämplig för uppdragsutbildning. De uppkomna positiva bieffekterna av projektets genomförande är att KY-utbildningarnas resurser har omhändertagits, lärdomar till framtida YH-projekt har erhållits, HiG har spridit akademisk kultur ut på landsbygden och själv berikats av den akademiska kulturen från Sandbacka Park, samt att studenterna i Hofors har fått hyressubventioner i en lugn studiemiljö och Hofors kommun fått sina lägenheter uthyrda. De negativa bieffekterna inkluderar att oklar ansvars- och resursfördelning skapat stress och extraarbete för lärare och studenter, samt att projektet har gått över budget vilket belastat andra verksamheter. Även om programmen nu är etablerade kvarstår problem vilka i framtiden behöver tas hand om. Denna utvärdering har därför utmynnat i rekommendationer om både framtida drift av programmen såväl som för framtida YH-projekt, vilka kan summeras som att: delprojekt i framtiden ges eget budgetansvar och tydliga ansvarsområden; autonomi ges till YH-programmen för både lärarlagsansvar och resurshantering; den akademiska miljöns etablering och utveckling prioriteras och kommunikationer förbättras; kommunkontakter organiseras; samt uppkomna erfarenheter och kompetenser tillvaratas.
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| 15. |
- Jakobsson, Kristina, et al.
(författare)
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Polybrominated diphenyl ethers (PBDEs) in serum from swedish men 1988-2002 : A longitudinal study
- 2005
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Polybrominated diphenyl ethers (PBDEs) have been extensively used as additive flame retardants since the 1970s. Their concentrations have been reported to increase with time both in humans and in wildlife from all environmental compartments. Retrospective time-trend studies conducted using environmental samples originating from the Swedish environment showed a peak in environmental levels in the mid-1980’s, after which environmental concentrations decreased or remained unchanged. In Swedish human breast milk, the concentrations of low-medium brominated diphenyl ethers redoubled every 5 years until the late 1990s; thereafter a decrease has been indicated, at least for BDE-475. However, there is yet no information on human time trends for hepta-, octa-, nona- and deca-BDEs, neither in Sweden or elsewhere. Further, no longitudinal studies on individual basis have yet been reported. In 1991 men with a high dietary intake of fish from the Baltic Sea, 12–20 meals/month, had considerably higher BDE-47 levels than men with negligible consumption of fish. These men were resampled in 2001. Time trends for PCB and DDE have been reported elsewhere. Here, we report data on time trends for PBDEs in these men.
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| 16. |
- Jakobsson, Maria, 1974-
(författare)
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Empirical Studies on Merger Policy and Collusive Behaviour
- 2007
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis consists of four studies focusing on empirical issues in industrial organization.Bid Rigging in Swedish Procurement Auctions: Using a unique data set of procurement auctions carried out by the Swedish National Road Administration, this paper addresses the issue of bid rigging in the Swedish asphalt-paving sector. Both market characteristics and the fact that the Swedish Competition Authority in 2003 initiated legal proceedings against a group of firms active in the market indicate the existence of collusive behaviour. If firms act competitively, they should submit independent bids, conditional on firm- and auction-specific differences. Reduced-form equations are estimated and the hypothesis of conditional independence is tested by analysing if the difference between observed and predicted bids correlates between firms. If negative correlation is observed, one possible explanation is bid rigging. The overall results indicate that collusion may be widespread in the industry and suggest further investigation of the market.Collusion in Procurement Auctions: Structural Estimation of Bidders' Costs: In this paper, the aim is to analyse the existence of collusion in asymmetric asphalt-procurement auctions. Firms that behave competitively should have private costs that are independent, conditional on available firm- and auction-specific information. The hypothesis of conditional independence can be tested and if it is rejected, a possible explanation is collusion. Using a constrained strategy equilibrium concept in solving for equilibrium bid strategies and firms' private costs makes it possible to test the hypothesis of conditional independence while at the same time controlling for firms' strategic considerations. The analysis is based on bid data from procurement auctions carried out in Sweden during the 1990's. The findings are that the hypothesis of conditional independence can be rejected for about half the firm-pairs that are tested. This suggests that collusive behaviour is plausible in the investigated market.An Econometric Analysis of the European Commission’s Merger Decisions: Using a sample of 96 mergers notified to the European Commission (EC) and logit-regression techniques, we analyse the EC’s decision process. We find that the probability of a phase-2 investigation and of a prohibition of the merger increases with the parties’ market shares. The probabilities increase also when the Commission finds high entry barriers or that the market structure post-merger is conductive to collusion. We do not find significant effects of “political” variables, such as the nationality of the merging firms.Comparing Merger Policies: The European Union versus the United States: Merger regulation affects large transactions in the market for corporate control in both the European Union (EU) and the United States (US). This paper compares and contrasts the relevant enforcement policies. US enforcement is broader-based as it attacks oligopoly, unilateral, and dominant firm concerns, while the EU policy focused almost entirely on market dominance. Our analysis of the enforcement policies shows that analytical and evidence considerations have more of an effect in the US, while institutional considerations matter more in the EU. Considering only cases subject to a theory of market dominance (dominant firm), the EU regime appears, on average, slightly more aggressive than US policy for relatively weak cases, while the US policy appears more aggressive for strong cases.
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| 17. |
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| 18. |
- Johnsson, Anna, 1975, et al.
(författare)
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Bioligand-mediated partitioning of radionuclides to the aqueous phase
- 2008
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Ingår i: Journal of Radioanalytical and Nuclear Chemistry. - : Springer Science and Business Media LLC. - 0236-5731 .- 1588-2780. ; 277:3, s. 637-644
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Tidskriftsartikel (refereegranskat)abstract
- The aqueous-phase partitioning of 59Fe, 147Pm, 234Th and 241Am by complexing compounds from subsurface bacteria has previously been studied in the presence of quartz sand. In this study the aqueous-phase partitioning of pico- to submicromolar amounts of 59Fe, 147Pm, 234Th and 241Am was analyzed in the presence of TiO2 and exudates from three species of subsurface bacteria: Pseudomonas fluorescens, Pseudomonas stutzeri, and Shewanella putrefaciens. All were grown under aerobic conditions and P. stutzeri and S. putrefaciens were grown under anaerobic conditions as well. The supernatants of the aerobic and anaerobic cultures were collected and radionuclide was added. TiO2, with BET surface area of 49.9 m2·g-1, was added to the supernatant radionuclide mix, and the pH was adjusted to approximately 8. After incubation, the amount of radionuclide in the liquid phase of the samples and controls was analyzed using scintillation method. Two types of values were calculated: solution% = the activity maintained in solution relative to the total activity, and Q-values = the quotient between the activity in samples and the activity in controls. Aerobic supernatants had solution% values between 89% and 100% for 59Fe and between 18 and 43% for 234Th. The solution% values for 241Am and 147Pm were less than 2% overall, but the Q-values were between 34 and 115 times more 241Am in bacterial supernatants than in controls. The corresponding values for 147Pm ranged from 6 to 20 times more than in the control. The solution% values for all elements in the presence of anaerobic supernatants were below 2%, but the Q-values clustered around 7 for 59Fe and ranging from 2 to 29 for 234Th, indicated that anaerobic supernatants partitioned these elements to the aqueous phase. Both aerobic and anaerobic supernatants tested positive for complexing compounds when analyzed, using the Chrome Azurol S assay. Complexation with excreted organic ligands is most likely the reason for the higher amounts of metals in samples than in the controls. Hence, aerobically and anaerobically excreted organic ligands seem able to influence the mobility of radionuclides in aerobic and anaerobic environments contaminated with these compounds.
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| 19. |
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| 20. |
- Olsson, Mattias, 1975, et al.
(författare)
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Sorption of trivalent plutonium onto UO2 and the effect of the solid phase on the Pu oxidation state
- 2005
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Ingår i: Radiochimica Acta. ; 93, s. 341-346
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Tidskriftsartikel (refereegranskat)abstract
- A problem with plutonium in sorption studiesis its tendency to occur in a mix of oxidation states. Thiswork was a study of the sorption of plutonium on the solidphase UO2 in a perchlorate medium as a function of pH where plutonium is kept in its trivalent oxidation state.Experiments also showed that uranium(IV) oxide can reducePu(IV) to Pu(III) in an acidic solution and maintain it in thatstate. It was observed at the same time that the chemicallyinert solid phases TiO2 and ThO2 possibly increase the rateof disproportionation of Pu(IV) at a pH of about 0.5. Inaccordance with previous studies MnO2 was found to have anoxidizing effect, converting Pu(IV) into Pu(VI).A comparison is made between the sorption of Th(IV),Pu(III) and Co(II) on UO2 and TiO2, and Pu(VI) on TiO2.
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| 21. |
- Persson, Roger, et al.
(författare)
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Trait anxiety and modeled exposure as determinants of Self-Reported Annoyance to Sound, Air Pollution and Other Environmental Factors in the home
- 2007
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Ingår i: International Archives of Occupational and Environmental Health. - : Springer Science and Business Media LLC. - 1432-1246 .- 0340-0131. ; 81:2, s. 179-191
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Tidskriftsartikel (refereegranskat)abstract
- Objectives We examined to what degree annoyance ratings to noise, air pollution and other common environmental factors in the home environment could be considered to mirror personality disposition in terms of habitual anxiety level and, when appropriate, objectively modeled noise and nitrogen emission (NOx). Methods A trait anxiety scale was introduced in a cross-sectional public health survey with 2,856 respondents. Of these, 705 had self-reported asthma and the rest constituted gender-matched referents. Annoyance to ten specific factors in the residential environment, mainly focusing on source-specific noise and air pollution, was assessed on a six-point likert scale. A-weighted energy equivalent continuous sound pressure level during a full day (24 h; L (Aeq,24)) as well as annual average NOx levels (mu g/m(3)) at the residential address were modeled with high resolution, using a road data base and a detailed emission data base for NOx. Results The two most prevalent complaints were annoyance to traffic noise and sounds from neighbors, which was reported by about 8% of the participants. Unadjusted logistic regression analyses using the continuous trait anxiety score as a predictor showed positive associations with ratings of annoyance from total traffic noise, sounds from neighbors, sound from ventilation, exhaust fumes from traffic, sounds from other installations, and vibrations from traffic (ORs between 1.37 and 2.14). Modeled noise and NOx exposure were positively related with annoyance to traffic noise and exhaust fumes, respectively. Adjustment of the trait anxiety scores for other individual characteristics and potential determinants did not change the overall pattern of results. Conclusion Trait anxiety scores were often mirrored in ratings of annoyance, which suggests caution when using annoyance reports either as a surrogate measure for environmental exposure on the individual-level in epidemiologic studies or when studying the moderating effects of annoyance on health outcomes.
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| 22. |
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| 23. |
- Sohn, Robert A., et al.
(författare)
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Explosive volcanism on the ultraslow-spreading Gakkel ridge, Arctic Ocean
- 2008
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 453:7199, s. 1236-1238
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Tidskriftsartikel (refereegranskat)abstract
- Roughly 60% of the Earth's outer surface is composed of oceanic crust formed by volcanic processes at mid-ocean ridges. Although only a small fraction of this vast volcanic terrain has been visually surveyed or sampled, the available evidence suggests that explosive eruptions are rare on mid-ocean ridges, particularly at depths below the critical point for seawater (3,000 m)1. A pyroclastic deposit has never been observed on the sea floor below 3,000 m, presumably because the volatile content of mid-ocean-ridge basalts is generally too low to produce the gas fractions required for fragmenting a magma at such high hydrostatic pressure. We employed new deep submergence technologies during an International Polar Year expedition to the Gakkel ridge in the Arctic Basin at 85° E, to acquire photographic and video images of 'zero-age' volcanic terrain on this remote, ice-covered ridge. Here we present images revealing that the axial valley at 4,000 m water depth is blanketed with unconsolidated pyroclastic deposits, including bubble wall fragments (limu o Pele)2, covering a large (>10 km2) area. At least 13.5 wt% CO2 is necessary to fragment magma at these depths3, which is about tenfold the highest values previously measured in a mid-ocean-ridge basalt4. These observations raise important questions about the accumulation and discharge of magmatic volatiles at ultraslow spreading rates on the Gakkel ridge5 and demonstrate that large-scale pyroclastic activity is possible along even the deepest portions of the global mid-ocean ridge volcanic system.
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