207 research outputs found
Thermophysical properties measurements performed for NASA
Thermoconductivity, specific heat, and density measurement test progra
Otters, sea stars, and glacial melt: top-down and bottom-up factors that influence kelp communities
Thesis (Ph.D.) University of Alaska Fairbanks, 2017Kelp beds are important features of the Alaska coastline and provide habitat, protect coastlines, and support commercial and subsistence harvests. Kelp beds are affected by top-down and bottom-up factors, which are changing due to human and climate-related impacts. The influences of these top-down and bottom-up factors on kelp beds are investigated in three chapters. My first chapter investigated the influence of glacial discharge on recruitment and early community development in subtidal kelp communities by monitoring benthic sessile algae and invertebrates on cleared rocks across a glacial gradient along with various physical and biological parameters in the summers of 2013-2014. It has been predicted that Alaska's glaciers will lose 30-60% of their volume by 2100. The melt from glaciers increases sedimentation and lowers salinity, impacting important habitat-providing kelp. I found that sites upstream from glacial discharge had higher kelp recruitment than downstream sites, and that up to 72% of the variation in community development was related to mobile invertebrates and kelp in the surrounding community. Glacially-influenced environmental factors did not explain any variation that was not already explained by biological factors. My second chapter explored whether patterns in the recruitment of the dominant canopy kelp, Nereocystis luetkeana and the subcanopy kelp, Saccharina latissima were a result of dispersal limitation or failure to grow to macroscopic size. My goals were to determine 1) whether glacial melt conditions affect adult fecundity (spore production) of either species, 2) how sedimentation affects early gametophyte growth and survival in each species, and 3) whether competitive interaction between species at the gametophyte stage is altered by sediments. I found that glacial melt conditions did not affect the fecundity of either species, but sedimentation affected survival and competition. Saccharina latissima was the superior competitor under high sediment conditions. Because glacially-influenced coastal areas often have little exposed hard substrate and predation by sea otters and sea stars on clams can provide hard substrate for kelp colonization, my third chapter examined methods for determining predation on clams by these predators without direct observation. I found that foraging pits of sea otters and sea stars could not be distinguished using quantitative measurements. In contrast, shell litter proved useful in quantifying relative foraging rates. Clam consumption by sea otters and sea stars was equal at all but one site. Collectively, my thesis chapters provide information on the effects of glacial discharge on microscopic and early kelp life stages in Alaska which can be incorporated into management practices.General introduction -- Chapter 1: Initial recruitment and early colonization of kelp-associated benthic communities varies in relation to glacial discharge -- Chapter 2: Supply and survival: glacial melt imposes limitations at the kelp microscopic life stage -- Chapter 3: Sea otter versus sea stars as major clam predators: evidence from foraging pits and shell litter -- General conclusion -- Literature cited
On an asymptotic optimization problem in finite, directed, weighted graphs
This paper is concerned with finite, directed, branch-weighted graphs, where each weight is a real number bearing the connotation of âpayoff.â The âaverage payoffâ of a k-branch path is defined as the sum of the weights along this path divided by k. It is shown that, as k approaches infinity, the maximum average payoff obtainable with paths initiating at a particular vertex is exactly the maximum of the average payoffs of all proper cycles reachable from that vertex. This result leads to a simple algorithm for finding a path which exhibits this maximum
Passing the Turing Test Does Not Mean the End of Humanity
In this paper we look at the phenomenon that is the Turing test. We consider how Turing originally introduced his imitation game and discuss what this means in a practical scenario. Due to its popular appeal we also look into different representations of the test as indicated by numerous reviewers. The main emphasis here, however, is to consider what it actually means for a machine to pass the Turing test and what importance this has, if any. In particular does it mean that, as Turing put it, a machine can âthinkâ. Specifically we consider claims that passing the Turing test means that machines will have achieved human-like intelligence and as a consequence the singularity will be upon us in the blink of an eye
Data consistency: toward a terminological clarification
The final publication is available at Springer via http://dx.doi.org/10.1007/978-3-319-21413-9_15Consistency is an inconsistency are ubiquitous term in
data engineering. Its relevance to quality is obvious, since consistency
is a commonplace dimension of data quality. However, connotations are
vague or ambiguous. In this paper, we address semantic consistency,
transaction consistency, replication consistency, eventual consistency and
the new notion of partial consistency in databases. We characterize their
distinguishing properties, and also address their differences, interactions
and interdependencies. Partial consistency is an entry door to living with
inconsistency, which is an ineludible necessity in the age of big data.Decker and F.D. Muñozâsupported by the Spanish MINECO grant TIN 2012-37719-C03-01.Decker, H.; Muñoz EscoĂ, FD.; Misra, S. (2015). Data consistency: toward a terminological clarification. En Computational Science and Its Applications -- ICCSA 2015: 15th International Conference, Banff, AB, Canada, June 22-25, 2015, Proceedings, Part V. Springer International Publishing. 206-220. https://doi.org/10.1007/978-3-319-21413-9_15S206220Abadi, D.: Consistency tradeoffs in modern distributed database system design: Cap is only part of the story. Computer 45(2), 37â42 (2012)Bailis, P. (2015). http://www.bailis.org/blog/Bailis, P., Ghodsi, A.: Eventual consistency today: limitations, extensions, and beyond. ACM Queue, 11(3) (2013)Balegas, V., Duarte, S., Ferreira, C., Rodrigues, R., Preguica, N., Najafzadeh, M., Shapiro, M.: Putting consistency back into eventual consistency. In: 10th EuroSys. ACM (2015). http://dl.acm.org/citation.cfm?doid=2741948.2741972Beeri, C., Bernstein, P., Goodman, N.: A sophisticateâs introduction to database normalization theory. In: VLDB, pp. 113â124 (1978)Berenson, H., Bernstein, P., Gray, J., Melton, J., OâNeil, E., OâNeil, P.: A critique of ansi sql isolation levels. SIGMoD Record 24(2), 1â10 (1995)Bermbach, D., Tai, S.: Eventual consistency: how soon is eventual? In: 6th MW4SOC. ACM (2011)BernabĂ©-Gisbert, J., Muñoz-EscoĂ, F.: Supporting multiple isolation levels in replicated environments. Data & Knowledge Engineering 7980, 1â16 (2012)Bernstein, P., Das, S.. Rethinking eventual consistency. In: SIGMOD 2013, pp. 923â928. ACM (2013)Bernstein, P., Hadzilacos, V., Goodman, N.: Concurrency Control and Recovery in Database Systems. Addison-Wesley (1987)Bertossi, L., Hunter, A., Schaub, T.: Inconsistency Tolerance. In: Bertossi, L., Hunter, A., Schaub, T. (eds.) Inconsistency Tolerance. LNCS, vol. 3300, pp. 1â14. Springer, Heidelberg (2005)Bobenrieth, A.: Inconsistencias por quĂ© no? Un estudio filosĂłfico sobre la lĂłgica paraconsistente. Premios Nacionales Colcultura. Tercer Mundo Editores. Magister Thesis, Universidad de los Andes, SantafĂ© de BogotĂĄ, Columbia (1995)Bosneag, A.-M., Brockmeyer, M.: A formal model for eventual consistency semantics. In: PDCS 2002, pp. 204â209. IASTED (2001)Browne, J.: Brewerâs cap theorem (2009). http://www.julianbrowne.com/article/viewer/brewers-cap-theoremCong, G., Fan, W., Geerts, F., Jia, X., Ma, S.: Improving data quality: consistency and accuracy. In: Proc. 33rd VLDB, pp. 315â326. ACM (2007)Dechter, R., van Beek, P.: Local and global relational consistency. Theor. Comput. Sci. 173(1), 283â308 (1997)Decker, H.: Translating advanced integrity checking technology to SQL. In: Doorn, J., Rivero, L. (eds.) Database integrity: challenges and solutions, pp. 203â249. Idea Group (2002)Decker, H.: Historical and computational aspects of paraconsistency in view of the logic foundation of databases. In: Bertossi, L., Katona, G.O.H., Schewe, K.-D., Thalheim, B. (eds.) Semantics in Databases 2001. LNCS, vol. 2582, pp. 63â81. Springer, Heidelberg (2003)Decker, H.: Answers that have integrity. In: Schewe, K.-D., Thalheim, B. (eds.) SDKB 2010. LNCS, vol. 6834, pp. 54â72. Springer, Heidelberg (2011)Decker, H.: New measures for maintaining the quality of databases. In: Murgante, B., Gervasi, O., Misra, S., Nedjah, N., Rocha, A.M.A.C., Taniar, D., Apduhan, B.O. (eds.) ICCSA 2012, Part IV. LNCS, vol. 7336, pp. 170â185. Springer, Heidelberg (2012)Decker, H.: A pragmatic approach to model, measure and maintain the quality of information in databases (2012). www.iti.upv.es/~hendrik/papers/ahrc-workshop_quality-of-data.pdf , www.iti.upv.es/~hendrik/papers/ahrc-workshop_quality-of-data_comments.pdf . Slides and comments presented at the Workshop on Information Quality. Univ, Hertfordshire, UKDecker, H.: Answers that have quality. In: Murgante, B., Misra, S., Carlini, M., Torre, C.M., Nguyen, H.-Q., Taniar, D., Apduhan, B.O., Gervasi, O. (eds.) ICCSA 2013, Part II. LNCS, vol. 7972, pp. 543â558. Springer, Heidelberg (2013)Decker, H.: Measure-based inconsistency-tolerant maintenance of database integrity. In: Schewe, K.-D., Thalheim, B. (eds.) SDKB 2013. LNCS, vol. 7693, pp. 149â173. Springer, Heidelberg (2013)Decker, H., Martinenghi, D.: Inconsistency-tolerant integrity checking. IEEE Transactions of Knowledge and Data Engineering 23(2), 218â234 (2011)Decker, H., Muñoz-EscoĂ, F.D.: Revisiting and improving a result on integrity preservation by concurrent transactions. In: Meersman, R., Dillon, T., Herrero, P. (eds.) OTM 2010. LNCS, vol. 6428, pp. 297â306. Springer, Heidelberg (2010)Dong, X.L., Berti-Equille, L., Srivastava, D.: Data fusion: resolving conflicts from multiple sources (2015). http://arxiv.org/abs/1503.00310Eswaran, K., Gray, J., Lorie, R., Traiger, I.: The notions of consistency and predicate locks in a database system. CACM 19(11), 624â633 (1976)Muñoz-EscoĂ, F.D., Ruiz-Fuertes, M.I., Decker, H., ArmendĂĄriz-Ăñigo, J.E., de MendĂvil, J.R.G.: Extending middleware protocols for database replication with integrity support. In: Meersman, R., Tari, Z. (eds.) OTM 2008, Part I. LNCS, vol. 5331, pp. 607â624. Springer, Heidelberg (2008)Fekete, A.: Consistency models for replicated data. In: Encyclopedia of Database Systems, pp. 450â451. Springer (2009)Fekete, A., Gupta, D., Lynch, V., Luchangco, N., Shvartsman, A.: Eventually-serializable data services. In: 15th PoDC, pp. 300â309. ACM (1996)Gilbert, S., Lynch, N.: Brewerâs conjecture and the feasibility of consistent, available, partition-tolerant web services. SIGACT News 33(2), 51â59 (2002)Golab, W., Rahman, M., Auyoung, A., Keeton, K., Li, X.: Eventually consistent: Not what you were expecting? ACM Queue, 12(1) (2014)Grant, J., Hunter, A.: Measuring inconsistency in knowledgebases. Journal of Intelligent Information Systems 27(2), 159â184 (2006)Gray, J., Lorie, R., Putzolu, G., Traiger, I.: Granularity of locks and degrees of consistency in a shared data base. In: Nijssen, G. (ed.) Modelling in Data Base Management Systems. North Holland (1976)Haerder, T., Reuter, A.: Principles of transaction-oriented database recovery. Computing Surveys 15(4), 287â317 (1983)Herlihy, M., Wing, J.: Linearizability: a correctness condition for concurrent objects. TOPLAS 12(3), 463â492 (1990)R. Ho. Design pattern for eventual consistency (2009). http://horicky.blogspot.com.es/2009/01/design-pattern-for-eventual-consistency.htmlIkeda, R., Park, H., Widom, J.: Provenance for generalized map and reduce workflows. In: CIDR (2011)Kempster, T., Stirling, C., Thanisch, P.: Diluting acid. SIGMoD Record 28(4), 17â23 (1999)Li, X., Dong, X.L., Meng, W., Srivastava, D.: Truth finding on the deep web: Is the problem solved? VLDB Endowment 6(2), 97â108 (2012)Lloyd, W., Freedman, M., Kaminsky, M., Andersen, D.: Donât settle for eventual: scalable causal consistency for wide-area storage with cops. In: 23rd SOPS, pp. 401â416 (2011)Lomet, D.: Transactions: from local atomicity to atomicity in the cloud. In: Jones, C.B., Lloyd, J.L. (eds.) Dependable and Historic Computing. LNCS, vol. 6875, pp. 38â52. Springer, Heidelberg (2011)Monge, P., Contractor, N.: Theory of Communication Networks. Oxford University Press (2003)Nicolas, J.-M.: Logic for improving integrity checking in relational data bases. Acta Informatica 18, 227â253 (1982)Muñoz-EscoĂ, F.D., IrĂșn, L., H. Decker: Database replication protocols. In: Encyclopedia of Database Technologies and Applications, pp. 153â157. IGI Global (2005)Oracle: Constraints. http://docs.oracle.com/cd/B19306_01/server.102/b14223/constra.htm (May 1, 2015)Ouzzani, M., Medjahed, B., Elmagarmid, A.: Correctness criteria beyond serializability. In: Encyclopedia of Database Systems, pp. 501â506. Springer (2009)Rosenkrantz, D., Stearns, R., Lewis, P.: Consistency and serializability in concurrent datanbase systems. SIAM J. Comput. 13(3), 508â530 (1984)Saito, Y., Shapiro, M.: Optimistic replication. JACM 37(1), 42â81 (2005)Sandhu, R.: On five definitions of data integrity. In: Proc. IFIP WG11.3 Workshop on Database Security, pp. 257â267. North-Holland (1994)Simmons, G.: Contemporary Cryptology: The Science of Information Integrity. IEEE Press (1992)Sivathanu, G., Wright, C., Zadok, E.: Ensuring data integrity in storage: techniques and applications. In: Proc. 12th Conf. on Computer and Communications Security, p. 26. ACM (2005)Svanks, M.: Integrity analysis: Methods for automating data quality assurance. Information and Software Technology 30(10), 595â605 (1988)Technet, M.: Data integrity. https://technet.microsoft.com/en-us/library/aa933058 (May 1, 2015)Terry, D.: Replicated data consistency explained through baseball. Technical report, Microsoft. MSR Technical Report (2011)Traiger, I., Gray, J., Galtieri, C., Lindsay, B.: Transactions and consistency in distributed database systems. ACM Trans. Database Syst. 7(3), 323â342 (1982)Vidyasankar, K.: Serializability. In: Encyclopedia of Database Systems, pp. 2626â2632. Springer (2009)Vogels, W.: Eventually consistent (2007). http://www.allthingsdistributed.com/2007/12/eventually_consistent.html . Other versions in ACM Queue 6(6), 14â19. http://queue.acm.org/detail.cfm?id=1466448 (2008) and CACM 52(1), 40â44 (2009)Wikipedia: Consistency model. http://en.wikipedia.org/wiki/Consistency_model (May 1, 2015)Wikipedia: Data integrity. http://en.wikipedia.org/wiki/Data_integrity (May 1, 2015)Wikipedia: Data quality. http://en.wikipedia.org/wiki/Data_quality (May 1, 2015)Yin, X., Han, J., Yu, P.: Truth discovery with multiple conflicting information providers on the web. IEEE Transactions of Knowledge and Data Engineering 20(6), 796â808 (2008)Young, G.: Quick thoughts on eventual consistency (2010). http://codebetter.com/gregyoung/2010/04/14/quick-thoughts-on-eventual-consistency/ (May 1, 2015
A formal characterization of SI-based ROWA replication protocols
Snapshot isolation (SI) is commonly used in some commercial DBMSs with a multiversion
concurrency control mechanism since it never blocks read-only transactions. Recent database
replication protocols have been designed using SI replicas where transactions are firstly
executed in a delegate replica and their updates (if any) are propagated to the rest of the
replicas at commit time; i.e. they follow the Read One Write All (ROWA) approach. This paper
provides a formalization that shows the correctness of abstract protocols which cover these
replication proposals. These abstract protocols differ in the properties demanded for achieving
a global SI level and those needed for its generalized SI (GSI) variant Âż allowing reads from old
snapshots. Additionally, we propose two more relaxed properties that also ensure a global GSI
level. Thus, some applications can further optimize their performance in a replicated system
while obtaining GSI.
© 2010 Elsevier B.V. All rights reserved.The authors wish to thank the reviewers for their valuable comments that helped us to greatly improve the quality and readability of this paper. This work has been supported by the Spanish Government under research grant TIN2009-14460-C03. Besides, the authors wish to thank the reviewers for their valuable comments that helped us to greatly improve the quality and readability of this paper.ArmendĂĄriz-Iñigo, J.; JuĂĄrez-RodrĂguez, J.; GonzĂĄlez De MendĂvil, J.; Garitagoitia, J.; IrĂșn Briz, L.; Muñoz EscoĂ, FD. (2011). A formal characterization of SI-based ROWA replication protocols. Data and Knowledge Engineering. 70(1):21-34. doi:10.1016/j.datak.2010.07.012S213470
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Tourists' English Expectations: Discourse Analysis of Attitudes towards Language and Culture on Travel Websites
While the importance of English as a lingua franca (ELF) in business and the media is well-studied, little attention has been paid to ELF in tourism. This study analyzes postings on websites such as TripAdvisor (http://www.tripadvisor.com/), which feature non-professional reviews of international travel destinations and services, in order to evaluate the effects of cultural capital, stereotypes and relative power on: expectations of English availability in non-English speaking countries, evaluation of the language spoken by EFL speakers (e.g. hotel clerks, shop owners), and attitudes towards speaking the local language.This study explores the issue of speech accommodation between the tourists and the local hospitality industry workers and other residents (Giles, Taylor, and Bourhis, 1973; Giles, Coupland, and Coupland, 1991; Giles and Powesland, 1997) and the likely factors leading to convergence/divergence as indicated by attitudes towards language choices. Website excerpts will show the circumstances in which travelers expect the locals (who deal with tourists) to speak English as well as how much of the local language the travelers are willing to learn and use.Findings indicate that the tourists' willingness to take responsibility for linguistic accommodation, tolerance for restricted English proficiency levels, and attitudes towards being exposed to the local culture and language differ according to the presumed cultural capital (Bourdieu, 1986, 1991; Hanks, 2005) - often governed by stereotypes - and relative power of the interlocutors, the visited location and the local language. The role of ELF in the tourism sector and attitudes toward the local residents and language(s) are highly relativized, such that the specificity of the local context must be taken into account. Proficiency in the English language itself is, in some locations, the source of presumed higher status and symbolic of luxury. The second important dynamic demonstrated to affect the levels and type of language expectation is the degree to which the traveler desires interaction with and exposure to the local culture, or wants to stay with familiar experiences in an "environmental bubble" (Cohen and Cooper, 1986). The differences in expectation of ELF demonstrate that traveler attitudes towards specific locations are key to determining linguistic needs
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