History and sensitivity comparison of two standard whole-sediment toxicity tests with crustaceans : the amphipod Hyalella azteca and the ostracod Heterocypris incongruens microbiotest

The review first details the development of the test procedures with Hyalella azteca which historically emerged as one of the recommended test species for whole-sediment assays and its gradual standardization and endorsement by national and international organizations. The sensitivity and precision of the H. azteca test for application on chemicals and on real world sediments is discussed. The review subsequently addresses the development of the whole sediment microbiotest with the ostracod crustacean Heterocypris incongruens with larvae of this test species hatched from dormant eggs (cysts), rendering this assay stock culture/maintenance free. The application of the 6-day ostracod microbiotest on sediments in Canada and in Belgium is discussed, as well as its endorsement by the ISO subsequent to an extensive international inter-laboratory ring test. The sensitivity of the amphipod and ostracod tests is compared by data from studies in which both assays were applied in parallel. A comparison of more than 1000 ostracod/amphipod data pairs of a 12-year river sediment monitoring study in Flanders/Belgium confirmed that both whole-sediment assays have a similar sensitivity and that the 6-day ostracod microbiotest is a valuable and cost-effective alternative to the 10-14 day amphipod test for evaluation of the toxic hazard of polluted sediments

Regional Jet Aircraft Competitiveness: Challenges and Opportunities

The regional jet aircraft is a unique market niche. Particularly suitable for providing capacity in the 30 to 90 seat range, these jets are often used to connect smaller airports to network carrier hubs, as well as to fill in during slow periods. The market is currently dominated by two manufacturers: Brazil\u27s Embraer and Canada\u27s Bombardier. Due to the nature of the global aircraft industry, Embraer and Bombardier are largely dependent on the international sale of their aircraft for steady revenue streams. Orders and deliveries of aircraft with fewer than 100 seats have grown rapidly over the past ten years. The study provides an overview of the aviation industry, particularly in the regional jet (RJ) sector, and examines country-specific factors affecting the number CRJ and ERJ deliveries. Results of stepwise regression indicate that a two-year lag of GDP, a two-year lag price of crude oil, a two-year lag of prior aircraft deliveries, and the country-specific land areas account for almost 40% of the variance in the aircraft deliveries. However, there are many additional factors which have an effect on RJs orders and deliveries

Satisfaction with Airline Service Quality: Familiarity Breeds Contempt

The objective of this study is to investigate frequency-of-flight issues and the differences between frequent and non-frequent flyers’ levels of satisfaction and the importance attributed to overall airline service quality and select attributes. The results indicate that the level of satisfaction with overall airline quality and select attributes decrease the more passengers fly. Conversely, the level of importance attributed to airline amenities increased with flight frequency. Perceptions of airline quality may vary between different nationalities and different socioeconomic groups. Differences between the short- and long-haul flights, as well as domestic and international services could also exist. Airline managers need to foster loyalty by improving passengers’ airline experience. This could be achieved by differentiating airline services to the segmented groups of passengers. However, a number of airlines suffer from a business culture where fuel and labor costs are more important than customer satisfaction

Candidate molecular ions for an electron electric dipole moment experiment

This paper is a theoretical work in support of a newly proposed experiment (R. Stutz and E. Cornell, Bull. Am. Soc. Phys. 89, 76 2004) that promises greater sensitivity to measurements of the electron's electric dipole moment (EDM) based on the trapping of molecular ions. Such an experiment requires the choice of a suitable molecule that is both experimentally feasible and possesses an expectation of a reasonable EDM signal. We find that the molecular ions PtH+, HfH+, and HfF+ are suitable candidates in their low-lying triplet Delta states. In particular, we anticipate that the effective electric fields generated inside these molecules are approximately of 73 GV/cm, -17 GV/cm, and -18 GV/cm respectively. As a byproduct of this discussion, we also explain how to make estimates of the size of the effective electric field acting in a molecule, using commercially available, nonrelativistic molecular structure software.Comment: 25 pages, 3 figures, submitted to Physical Review

Physical random functions

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2003.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Includes bibliographical references (p. 87-89).In general, secure protocols assume that participants are able to maintain secret key information. In practice, this assumption is often incorrect as an increasing number of devices are vulnerable to physical attacks. Typical examples of vulnerable devices are smartcards and Automated Teller Machines. To address this issue, Physical Random Functions are introduced. These are Random Functions that are physically tied to a particular device. To show that Physical Random Functions solve the initial problem, it must be shown that they can be made, and that it is possible to use them to provide secret keys for higher level protocols. Experiments with Field Programmable Gate Arrays are used to evaluate the feasibility of Physical Random Functions in silicon.by Blaise L.P. Gassend.S.M

Production of Biodiesel from Waste Oil via Catalytic Distillation

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Brown-York Energy and Radial Geodesics

We compare the Brown-York (BY) and the standard Misner-Sharp (MS) quasilocal energies for round spheres in spherically symmetric space-times from the point of view of radial geodesics. In particular, we show that the relation between the BY and MS energies is precisely analogous to that between the (relativistic) energy E of a geodesic and the effective (Newtonian) energy E_{eff} appearing in the geodesic equation, thus shedding some light on the relation between the two. Moreover, for Schwarzschild-like metrics we establish a general relationship between the BY energy and the geodesic effective potential which explains and generalises the recently observed connection between negative BY energy and the repulsive behaviour of geodesics in the Reissner-Nordstrom metric. We also comment on the extension of this connection between geodesics and the quasilocal BY energy to regions inside a horizon.Comment: v3: 7 pages, shortened and revised version to appear in CQ

Community energy retail tariffs in Singapore: opportunities for peer-to-peer and time-of-use versus vertically integrated tariffs

The deregulation of Singapore’s retail electricity market in 2018 and the rapid adoption of solar rooftops have led to the emergence of a new type of energy transaction, wherein prosumers require flexible tariffs that reflect their willingness to respond to market price signals as well as new business models. The move toward community energy schemes, where prosumers can trade their surplus electricity locally, and the implications this has for tariff design motivates our study. We propose a portfolio of stylized retail tariffs for different market organizations. Among the proposed configurations are time-of-use (ToU), default vertical and peer-to-peer (P2P) tariffs, the last of which operates through a blockchain platform. In this study, each Singaporean district is balanced as a potential future microgrid. An iterative double-auction mechanism is designed to calculate a distributed P2P tariff, looking to maximize the benefit for stakeholders. This tariff is then cleared and compared with a bespoke retail ToU tariff as well as Singapore’s monopolistic regulated vertical tariff