22,973 research outputs found
An Interactive Game Approach to Learning in Historical Geology and Paleontology
This article describes an interactive game that can be used in conjunction with traditional laboratory work, group discussions, student presentations, and writing exercises. It provides an enjoyable and motivating dimension to a university seminar/lab course in Historical Geology and Paleontology. A simple spelling-bee-type game evolves over ten weeks into a room-sized board game based on the geologic time scale. The game helps students learn fossil morphology, identification, classification, and paleoecology while illustrating the occurrences of important fossil groups, sea level fluctuations, and orogenic events through time. It also serves as an effective means for evaluating student progress in the laboratory. Although the game content is designed for geology majors in a university setting, the time scale game board can easily be adapted to a secondary school environment. Educational levels: Graduate or professional
Finite-key security analysis for multilevel quantum key distribution
We present a detailed security analysis of a d-dimensional quantum key
distribution protocol based on two and three mutually unbiased bases (MUBs)
both in an asymptotic and finite key length scenario. The finite secret key
rates are calculated as a function of the length of the sifted key by (i)
generalizing the uncertainly relation-based insight from BB84 to any d-level
2-MUB QKD protocol and (ii) by adopting recent advances in the second-order
asymptotics for finite block length quantum coding (for both d-level 2- and
3-MUB QKD protocols). Since the finite and asymptotic secret key rates increase
with d and the number of MUBs (together with the tolerable threshold) such QKD
schemes could in principle offer an important advantage over BB84. We discuss
the possibility of an experimental realization of the 3-MUB QKD protocol with
the orbital angular momentum degrees of freedom of photons.Comment: v4: close to the published versio
High Sequestration, Low Emission, Food Secure Farming. Organic Agriculture - a Guide to Climate Change & Food Security
- affordable high sequestration practices based on local resources
- enables continuous farmer-based adaptation to climate change
- ideal for the improvement of the world’s 400 million smallholder farms
- locally adapted, affordable and people centered
- empowers local communities
- established practices, systems and markets
- experience, practices and expertise to shar
Identification of Binuclear Acyl Complexes as Intermediates in the CO-induced Conversion of [(η^5-C_5H_5)Co(CO)(Me)]_2 into Acetone, and [(η^5-C_5H_5)Co(CO)(Et)]_2 into Pentan-3-one
Studies of the carbonylation of [(η^5-C_5H_5)Co(CO)(R)]_2(R = Me, Et) at temperatures below ambient have revealed that these complexes may be converted into ketones via binuclear diacyl complexes [(η^5-C_5H_5)Co(CO)(COR)]_2; the postulated mechanistic pathway circumvents the earlier-identified intermediate (η^5-C_5H_5)Co(CO)R_2, and involves alkyl transfer from a Co^(II) acyl complex as a critical step
Multi-criteria scheduling of pipeline workflows
Mapping workflow applications onto parallel platforms is a challenging
problem, even for simple application patterns such as pipeline graphs. Several
antagonist criteria should be optimized, such as throughput and latency (or a
combination). In this paper, we study the complexity of the bi-criteria mapping
problem for pipeline graphs on communication homogeneous platforms. In
particular, we assess the complexity of the well-known chains-to-chains problem
for different-speed processors, which turns out to be NP-hard. We provide
several efficient polynomial bi-criteria heuristics, and their relative
performance is evaluated through extensive simulations
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