Differential responses of Nile tilapia (Oreochromis niloticus) to fin clip wounding and related stress: perspectives

The debate around fish welfare is intensifying in The Netherlands. As a result, more research is carried out to enhance knowledge on fish welfare in aquaculture. Detailed information is lacking on how production procedures causing discomfort to the fish may affect welfare. That fish must perceive adversive stimuli follows from the fact that nociceptive mechanisms similar to those in mammals are present in fish. However, whether and how nociceptive stimuli are perceived or interpreted by a fish is a far more difficult question that requires significantly more effort from fundamental research, both neurophysiological and behavioural studies, than now available. The study presented in this report aimed to define selected readout for the acute response to a supposedly painful stimulus: a standardised tailfin clip to a common carp. In conclusion, we succeeded to demonstrate differential, stronger responses to a presumed painful stimulus than to the handling stress per se associated with the administration of the pain stimulus. These parameters will be the focus of future research within this welfare project

Nuclear Power: a Hedge against Uncertain Gas and Carbon Prices?

High fossil fuel prices have rekindled interest in nuclear power. This paper identifies specific nuclear characteristics making it unattractive to merchant generators in liberalised electricity markets, and argues that non-fossil fuel technologies have an overlooked à ¢à  à  option valueà ¢à  à  given fuel and carbon price uncertainty. Stochastic optimisation estimates the company option value of keeping open the choice between nuclear and gas technologies. This option value decreases sharply as the correlation between electricity, gas, and carbon prices rises, casting doubt on whether private investorsà ¢à  à  fuel-mix diversification incentives in electricity markets are aligned with the social value of a diverse fuel-mix

Auxotrophy accounts for nodulation defect of most Sinorhizobium meliloti mutants in the branched-chain amino acid biosynthesis pathway

Some Sinorhizobium meliloti mutants in genes involved in isoleucine, valine, and leucine biosynthesis were previously described as being unable to induce nodule formation on host plants. Here, we present a reappraisal of the interconnection between the branched-chain amino acid biosynthesis pathway and the nodulation process in S. meliloti. We characterized the symbiotic phenotype of seven mutants that are auxotrophic for isoleucine, valine, or leucine in two closely related S. meliloti strains, 1021 and 2011. We showed that all mutants were similarly impaired for nodulation and infection of the Medicago sativa host plant. In most cases, the nodulation phenotype was fully restored by the addition of the missing amino acids to the plant growth medium. This strongly suggests that auxotrophy is the cause of the nodulation defect of these mutants. However, we confirmed previous findings that ilvC and ilvD2 mutants in the S. meliloti 1021 genetic background could not be restored to nodulation by supplementation with exogenous amino acids even though their Nod factor production appeared to be normal.Instituto de Biotecnologia y Biologia MolecularFacultad de Ciencias Exacta

Het effect van verhoogde ammonia concentratie in het water op fysiologie, groei en voeropname van Afrikaanse meerval (Clarias gariepinus)

IMARES onderzocht het effect van de ammoniaconcentratie in het kweekwater op groei, voeropname en fysiologie van Afrikaanse meerval (Clarias gariepinus). Het doel van dit onderzoek was het vaststellen van de maximale ammoniaconcentratie (grenswaarde) waarbij geen negatieve effecten op welzijn van de vis en de productie waar te nemen zijn

MAXI J1659-152: the shortest orbital period black-hole binary

Following the detection of a bright new X-ray source, MAXI J1659-152, a series of observations was triggered with almost all currently flying high-energy missions. We report here on XMM-Newton, INTEGRAL and RXTE observations during the early phase of the X-ray outburst of this transient black-hole candidate. We confirm the dipping nature in the X-ray light curves. We find that the dips recur on a period of 2.4139+/-0.0005 hrs, and interpret this as the orbital period of the system. It is thus the shortest period black-hole X-ray binary known to date. Using the various observables, we derive the properties of the source. The inclination of the accretion disk with respect to the line of sight is estimated to be 60-75 degrees. The companion star to the black hole is possibly a M5 dwarf star, with a mass and radius of about 0.15 M_sun and 0.23 R_sun, respectively. The system is rather compact (orbital separation is about 1.35 R_sun) and is located at a distance of roughly 7 kpc. In quiescence, MAXI J1659-152 is expected to be optically faint, about 28 mag in the V-band.Comment: 5 pages, 4 figures, to be published in the proceedings of the 4th International MAXI Workshop `The First Year of MAXI: Monitoring variable X-ray sources', 2010 Nov 30 - Dec 2, Tokyo, Japa

Long-term Energy Supply Contracts in European Competition Policy: Fuzzy not Crazy

Long-term supply contracts often have ambiguous effects on the competitive structure, investment and consumer welfare in the long term. In a context of market building, these effects are likely to be worsened and thus even harder to assess. Since liberalization and especially since the release of the Energy Sector Enquiry in early 2007, the portfolio of long-term supply contracts of the former incumbents have become a priority for review by the European Commission and the national competition authorities. It is widely believed that European Competition authorities take a dogmatic view on these contracts and systemically emphasize the risk of foreclosure over their positive effects on investment and operation. This paper depicts the methodology that has emerged in the recent line of cases and argues that this interpretation is largely misguided. It shows that a multiple-step approach is used to reduce regulation costs and balance anti-competitive effects with potential efficiency gains. However, if an economic approach is now clearly implemented, competition policy is constrained by the procedural aspect of the legal process and the remedies imposed remain open for discussion.Massachusetts Institute of Technology. Center for Energy and Environmental Policy Research

Cherenkov Telescopes as Optical Telescopes for Bright Sources: Today's Specialised Thirty Metre Telescopes?

Imaging Atmospheric Cherenkov Telescopes (IACTs) use large-aperture (~ 10 - 30 m) optical telescopes with arcminute angular resolution to detect TeV gamma-rays in the atmosphere. I show that IACTs are well-suited for optical observations of bright sources (V <= 8 - 10), because these sources are brighter than the sky background. Their advantages are especially great on rapid time-scales. Thus, IACTs are ideal for studying many phenomena optically, including transiting exoplanets and the brightest gamma-ray bursts. In principle, an IACT could achieve millimagnitude photometry of these objects with second-long exposures. I also consider the potential for optical spectroscopy with IACTs, finding that their poor angular resolution limits their usefulness for high spectral resolutions, unless complex instruments are developed. The high photon collection rate of IACTs is potentially useful for precise polarimetry. Finally, I briefly discuss the broader possibilities of extremely large, low resolution telescopes, including a 10" resolution telescope and spaceborne telescopes.Comment: 10 pages, 3 figures, accepted by MNRA

First Results From The Taiwanese-American Occultation Survey (TAOS)

Results from the first two years of data from the Taiwanese-American Occultation Survey (TAOS) are presented. Stars have been monitored photometrically at 4 Hz or 5 Hz to search for occultations by small (~3 km) Kuiper Belt Objects (KBOs). No statistically significant events were found, allowing us to present an upper bound to the size distribution of KBOs with diameters 0.5 km < D < 28 km.Comment: 5 pages, 5 figure, accepted in Ap