On the effects of geometry control on the performance of overtopping wave energy converters

Overtopping wave energy converters (OWECs) are designed to extract energy from ocean waves based on wave overtopping into a reservoir, which is emptied into the ocean through a set of low-head turbines, and typically feature a low crest freeboard and a smooth impermeable steep slope. In the process of optimizing the performance of OWECs, the question arises whether adapting the slope geometry to the variable wave characteristics at the deployment site (i.e., geometry control) can increase the overall hydraulic efficiency and overall hydraulic power compared to a fixed slope geometry. The effect of five different geometry control scenarios on the overall hydraulic efficiency and overall hydraulic power of OWECs has been simulated for three possible deployment sites using empirical prediction formulae. The results show that the effect of an adaptive slope angle is relatively small. On the other hand, adapting the crest freeboard of the OWECs to the wave characteristics increases the overall hydraulic efficiency and power. Based on the simulations, gains in overall hydraulic power of at least 30% are achievable when applying an adaptive crest freeboard compared to a fixed crest freeboard

Quinone-mediated extracellular electron transfer processes in ex situ biomethanation reactors

Redox mediators are used in a wide diversity of systems including biological ones. We investigated the effect of adding an artificial quinone (2,7-AQDS) as external redox molecule to an anaerobic digester system dominated by hydrogenotrophic methanogens. When oxidized AQDS was present, the methanogens diverted electrons from H2 to reduce AQDS instead of CO2. The AQDS reduction process was accompanied by a temporary CH4 inhibition, which was re-established several days after the full reduction of AQDS to AH2QDS. The presence of AQDS furthermore resulted in a community shift from Methanobacterium as the dominant methanogen to a more diverse community of methanogens. Protein expression profiles showed a shift in cofactor preference of the adapted community, as a potential response mechanism to AQDS inhibition. AH2QDS was only used as electron donor to a limited extent. Stable isotope incorporation experiments here indicated that the acetogen Acetoanaerobium used AH2QDS to reduce CO2 into acetate.</p

Produktorienteret miljøindsats i landbrugssektoren - forudsætninger

For at styrke den produktorienterede miljøindsats i landbruget nedsatte Miljøstyrelsen primo 2003 et produktkædepanel for landbrugsområdet. Panelets primære mål er at fremme udvikling og afsætning af landbrugsprodukter, der set i et livscyklusperspektiv ("fra jord til jord") er mindre miljøbelastende end tilsvarende traditionelle produkter. Som fundament for panelets arbejde er udarbejdet denne rapport, som beskriver de eksisterende forudsætninger for en produktorienteret indsats i sektoren - i form af en kortlægning af relevante projekter/tiltag. Denne rapport har dannet udgangspunkt for udarbejdelsen af et såkaldt fremsyn på området, som er publiceret særskilt. Fremsynet og information om panelets arbejde i øvrigt kan fås på www.produktpanel-landbrug.dk. En produktorienteret indsats vil altid være et supplement til de eksisterende overordnede reguleringer af samfundets adfærd, forbrug og udledninger. Vi vil stadig i fremtiden opleve berettiget miljøarbejde, der tager udgangspunkt i en konkret produktion eller proces eller i ønsket om at reducere en arealbelastning. Med produktorientering følger en anderledes og mere nuanceret opfattelse af, hvad der er "godt og dårligt" for miljøet, hvilke områder, der skal prioriteres i fødevaresektorens miljøindsats, og hvad miljøarbejdet kan omfatte i alle led i fødevarernes produktkæde. Et produktorienteret miljøarbejde stiller krav til og udfordrer alle aktører i produktkæderne. Der skal ikke alene udveksles og håndteres oplysninger om produktets miljøpåvirkning bagud og fremad i produktkæden, men der skal også ageres på baggrund af de erkendelser, denne udveksling af oplysninger giver anledning til. Helhedsorienteringen skaber også muligheder for at synliggøre og dokumentere valg undervejs i produktkæden. Produktorientering giver dermed en enestående mulighed for aktører/virksomheder for at dokumentere adfærd og valg overfor aftagere (herunder forbrugeren). Også for landbrugs- og gartnerierhvervet er produktorienteringen en udfordring. En kvalificeret diskussion af muligheder og perspektiver i produktorienteringen i landbrugserhvervet er derfor langt fra kun et spørgsmål om værktøjer, opgørelsesmetoder og mulighederne for afsætning af miljødokumenterede varer. Produktorienteringen er i langt højere grad den ramme, hvori f.eks. nedenstående spørgsmål kan diskuteres: Hvilke langsigtede scenarier for landbrugserhvervet er tænkelige? Hvilke strategier kan anlægges for erhvervsudvikling, forskning, kompetenceudvikling etc. for bedst muligt at sigte på de mest attraktive scenarier? Hvordan bringes aktørerne i spil, og hvordan skal ansvar fordeles? De hidtidige erfaringer med produktorientering viser, at en væsentlig forudsætning for succes er åbenhed og kommunikation i produktkæderne

Prevalence of Peripheral Artery Disease is Higher in Persons Living with HIV Compared to Uninfected Controls

OBJECTIVE: Ankle-brachial index (ABI) is an excellent tool for diagnosing peripheral artery disease (PAD). We aimed to determine the prevalence and risk factors for PAD in people living with HIV (PLWH) compared to uninfected controls. We hypothesized that prevalence of PAD would be higher among PLWH than among controls independent of traditional cardiovascular disease (CVD) risk factors. METHODS: PLWH aged ≥40 were recruited from the Copenhagen comorbidity in HIV infection (COCOMO) study. Sex and age matched uninfected controls were recruited from the Copenhagen General Population Study. We defined PAD as ankle-brachial index (ABI) ≤ 0.9 and assessed risk factors for PAD using logistic regression adjusting for age, sex, smoking status, dyslipidemia, diabetes, hypertension and hsCRP. RESULTS: Among 908 PLWH and 11,106 controls, PAD was detected in 112 (12% CI [95% 10-14]) and 623 (6% [95% 5-6]), respectively (p<0.001); odds ratio (OR)=2.4 [95% 1.9-2.9], adjusted OR=1.7 [95% 1.3-2.3, p<.001]. Traditional CVD risk factors, but not HIV-related variables were associated with PAD. The strength of the association between PAD and HIV tended to be higher with older age (p=0.052, adjusted test for interaction). CONCLUSION: Prevalence of PAD is higher among PLWH compared to uninfected controls, especially among older persons, and remains so after adjusting for traditional CVD risk factors. Our findings expand the evidence base that PLWH have excess arterial disease to also include PAD. The exact biological mechanisms causing this excess risk remain to be elucidated. Until then, focus on management of modifiable traditional risk factors is important

Nuclear structure and reaction studies at SPIRAL

The SPIRAL facility at GANIL, operational since 2001, is described briefly. The diverse physics program using the re-accelerated (1.2 to 25 MeV/u) beams ranging from He to Kr and the instrumentation specially developed for their exploitation are presented. Results of these studies, using both direct and compound processes, addressing various questions related to the existence of exotic states of nuclear matter, evolution of new "magic numbers", tunnelling of exotic nuclei, neutron correlations, exotic pathways in astrophysical sites and characterization of the continuum are discussed. The future prospects for the facility and the path towards SPIRAL2, a next generation ISOL facility, are also briefly presented.Comment: 48 pages, 27 figures. Accepted for publication in Journal of Physics