973 resultados para STL-Format
Resumo:
Transient simulations are widely used in studying the past climate as they provide better comparison with any exisiting proxy data. However, multi-millennial transient simulations using coupled climate models are usually computationally very expensive. As a result several acceleration techniques are implemented when using numerical simulations to recreate past climate. In this study, we compare the results from transient simulations of the present and the last interglacial with and without acceleration of the orbital forcing, using the comprehensive coupled climate model CCSM3 (Community Climate System Model 3). Our study shows that in low-latitude regions, the simulation of long-term variations in interglacial surface climate is not significantly affected by the use of the acceleration technique (with an acceleration factor of 10) and hence, large-scale model-data comparison of surface variables is not hampered. However, in high-latitude regions where the surface climate has a direct connection to the deep ocean, e.g. in the Southern Ocean or the Nordic Seas, acceleration-induced biases in sea-surface temperature evolution may occur with potential influence on the dynamics of the overlying atmosphere. The data provided here are from both accelerated and non-accelerated runs as decadal mean values.
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In cognitive tests, animals are often given a choice between two options and obtain a reward if they choose correctly. We investigated whether task format affects subjects' performance in a physical cognition test. In experiment 1, a two-choice memory test, 15 marmosets, Callithrix jacchus, had to remember the location of a food reward over time delays of increasing duration. We predicted that their performance would decline with increasing delay, but this was not found. One possible explanation was that the subjects were not sufficiently motivated to choose correctly when presented with only two options because in each trial they had a 50% chance of being rewarded. In experiment 2, we explored this possibility by testing eight naïve marmosets and seven squirrel monkeys, Saimiri sciureus, with both the traditional two-choice and a new nine-choice version of the memory test that increased the cost of a wrong choice. We found that task format affected the monkeys' performance. When choosing between nine options, both species performed better and their performance declined as delays became longer. Our results suggest that the two-choice format compromises the assessment of physical cognition, at least in memory tests with these New World monkeys, whereas providing more options, which decreases the probability of obtaining a reward when making a random guess, improves both performance and measurement validity of memory. Our findings suggest that two-choice tasks should be used with caution in comparisons within and across species because they are prone to motivational biases.
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This document specifies the NetCDF file format of EGO-gliders that is used to distribute glider data, metadata and technical data. It documents the standards used therein; this includes naming conventions as well as metadata content. It was initiated in October 2012, based on OceanSITES, Argo and ANFOG user's manuals. Everyone’s Gliding Observatories - EGO is dedicated to the promotion of the glider technology and its applications. The EGO group promotes glider applications through coordination, training, liaison between providers and users, advocacy, and provision of expert advice. We intend to favor oceanographic experiments and the operational monitoring of the oceans with gliders through scientific and international collaboration. We provide news, support, information about glider projects and glider data management, as well as resources related to gliders. All EGO data are publicly available. More information about the project is available at: http://www.ego-network.org
Resumo:
Symbiotic relationships between insects and beneficial microbes are very common in nature, especially within the Hemiptera. The brown marmorated stink bug, Halyomorpha halys Stål, harbors a symbiont, Pantoea carbekii, within the fourth region of the midgut in specialized crypts. In this dissertation, I explored this insect- microbe relationship. I determined that the brown marmorated stink bug is heavily reliant on its symbiont, and that experimental removal of the symbiont from the egg mass surface prior to nymphal acquisition led to lower survival, longer development, lower fecundity, and aberrant nymphal behavior. Additionally, I determined that even when the symbiont is acquired and housed in the midgut crypts, it is susceptible to stressors. Stink bugs reared at a higher temperature showed lower survival, longer development, and a cease in egg mass production, and when bugs were screened for their symbiont, fewer had successfully retained it while under heat stress. Finally, with the knowledge that the stink bug suffers decreases in fitness when its symbiont is missing or stressed, I wanted to determine if targeting the symbiont was a possible management technique for the stink bug. I tested the efficacy of a number of different insecticidal and antimicrobial products to determine whether prevention of symbiont acquisition from the egg mass was possible, and results indicated that transmission of the symbiont from the egg mass to the newly hatched nymph was negatively impacted when certain products were applied (namely surfactants or products containing surfactants). Additionally, direct effects on hatch rate and survival were reported for certain products, namely the insect growth regulator azadirachtin, which suggests that nymphs can pick up residues from the egg mass surface while probing for the symbiont. I conclude that P. carbekii plays a critically important role in the survival of its host, the brown marmorated stink bug, and its presence on the egg mass surface before nymphal hatch makes it targetable as a potential management technique.
Resumo:
Every Argo data file submitted by a DAC for distribution on the GDAC has its format and data consistency checked by the Argo FileChecker. Two types of checks are applied: 1. Format checks. Ensures the file formats match the Argo standards precisely. 2. Data consistency checks. Additional data consistency checks are performed on a file after it passes the format checks. These checks do not duplicate any of the quality control checks performed elsewhere. These checks can be thought of as “sanity checks” to ensure that the data are consistent with each other. The data consistency checks enforce data standards and ensure that certain data values are reasonable and/or consistent with other information in the files. Examples of the “data standard” checks are the “mandatory parameters” defined for meta-data files and the technical parameter names in technical data files. Files with format or consistency errors are rejected by the GDAC and are not distributed. Less serious problems will generate warnings and the file will still be distributed on the GDAC. Reference Tables and Data Standards: Many of the consistency checks involve comparing the data to the published reference tables and data standards. These tables are documented in the User’s Manual. (The FileChecker implements “text versions” of these tables.)
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Half-Unit-Biased format is based on shifting the representation line of the binary numbers by half Unit in the Last Place. The main feature of this format is that the round to nearest is carried out by a simple truncation, preventing any carry propagation and saving time and area. Algorithms and architectures have been defined for addition/substraction and multiplication operations under this format. Nevertheless, the division operation has not been confronted yet. In this paper we deal with the floating-point division under HUB format, studying the architecture for the digit recurrence method, including the on-the-fly conversion of the signed digit quotient.
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Teachers' failure to utilise MBL activities more widely may be due to not recognising their capacity to transform the nature of laboratory activities to be more consistent with contemporary constructivist theories of learning. This research aimed to increase understanding of how MBL activities specifically designed to be consistent with a constructivist theory of learning support or constrain student construction of understanding. The first author conducted the research with his Year 11 physics class of 29 students. Dyads completed nine tasks relating to kinematics using a Predict-Observe-Explain format. Data sources included video and audio recordings of students and teacher during four 70-minute sessions, students' display graphs and written notes, semi-structured student interviews, and the teacher's journal. The study identifies the actors and describes the patterns of interactions in the MBL. Analysis of students' discourse and actions identified many instances where students' initial understanding of kinematics were mediated in multiple ways. Students invented numerous techniques for manipulating data in the service of their emerging understanding. The findings are presented as eight assertions. Recommendations are made for developing pedagogical strategies incorporating MBL activities which will likely catalyse student construction of understanding.
Resumo:
Bid opening in e-auction is efficient when a homomorphic secret sharing function is employed to seal the bids and homomorphic secret reconstruction is employed to open the bids. However, this high efficiency is based on an assumption: the bids are valid (e.g., within a special range). An undetected invalid bid can compromise correctness and fairness of the auction. Unfortunately, validity verification of the bids is ignored in the auction schemes employing homomorphic secret sharing (called homomorphic auction in this paper). In this paper, an attack against the homomorphic auction in the absence of bid validity check is presented and a necessary bid validity check mechanism is proposed. Then a batch cryptographic technique is introduced and applied to improve the efficiency of bid validity check.
Resumo:
Instead of the costly encryption algorithms traditionally employed in auction schemes, efficient Goldwasser-Micali encryption is used to design a new sealed-bid auction. Multiplicative homomorphism instead of the traditional additive homomorphism is exploited to achieve security and high efficiency in the auction. The new scheme is the currently known most efficient non-interactive sealed-bid auction with bid privacy.
Resumo:
In this work, we examine unbalanced computation between an initiator and a responder that leads to resource exhaustion attacks in key exchange protocols. We construct models for two cryp-tographic protocols; one is the well-known Internet protocol named Secure Socket Layer (SSL) protocol, and the other one is the Host Identity Protocol (HIP) which has built-in DoS-resistant mechanisms. To examine such protocols, we develop a formal framework based on Timed Coloured Petri Nets (Timed CPNs) and use a simulation approach provided in CPN Tools to achieve a formal analysis. By adopting the key idea of Meadows' cost-based framework and re¯ning the de¯nition of operational costs during the protocol execution, our simulation provides an accurate cost estimate of protocol execution compar- ing among principals, as well as the percentage of successful connections from legitimate users, under four di®erent strategies of DoS attack.