1,724 research outputs found
Cut-elimination, substitution and normalisation
No full textDate of Acceptance: 01/2015We present a proof (of the main parts of which there is a formal version, checked with the Isabelle proof assistant) that, for a G3-style calculus covering all of intuitionistic zero-order logic, with an associated term calculus, and with a particular strongly normalising and confluent system of cut-reduction rules, every reduction step has, as its natural deduction translation, a sequence of zero or more reduction steps (detour reductions, permutation reductions or simplifications). This complements and (we believe) clarifies earlier work by (e.g.) Zucker and Pottinger on a question raised in 1971 by Kreisel.Peer reviewe
Sea surface temperature and salinity collected aboard the S.A. AGULHAS II and S.A. AGULHAS in the South Atlantic Ocean and Southern Ocean from 2010-12-08 to 2017-02-02 (NCEI Accession 0170743)
No full textThis accession contains sea surface temperature and salinity data collected from 2010 to 2017 in the South Atlantic Ocean and Southern Ocean from S.A. Agulhas and Agulhas-II research vessels, in the framework of South African National Antarctic Programme (SANAP), South African Department of Environmental Affairs (DEA) and Italian National Antarctic Research Programme (PNRA) scientific activities. Measurements have been obtained through termosalinograph (TSG) during several cruises to both Antarctica and sub-Antarctic islands. On-board TSG devices have been regularly calibrated and continuously monitored in-between cruises; no appreciable sensor drift emerged. Independent water samples taken along the cruises have been used to validate the data; salinity measurement error was a few hundredths of a unit on the practical salinity scale. A careful quality control allowed to discard bad data for each single campaign. Furthermore, a seaice flag has been included in the dataset for identifying valid data which could have been slightly affected by sea ice contamination
Quest Volume 9 Number 1
No full textOur changing oceans: Isabelle Ansorge and Mike Roberts explain South Africa's role in investigating the changes; Robots in the ocean Thomas Mtsonti and Isabelle Ansorge explain the global ocean observing system; New ways to study zooplankton: Innovation has changed our understanding of this vital link in the ocean's food chains; Invasive aliens in Antarctica: Even the remote Antarctic continent has problems with invasive alien species; High in the food chain - seals in the Southern Ocean: Three decades of research have given scientists a lot of insight into the importance of seals in the Southern Ocean; A swirly world - measuring ocean currents from the new SA Agulhas II; Tammy Morris, Isabelle Ansorge and Patrick Vianello explain the importance of understanding ocean currents: Gliders in the ocean Africa's first ocean gliders navigate the turbid and remote Antarctic waters; Microbes in the ocean Gerda du Plessis introduces us to microscopic plankton: Life at sea Christopher Jacobs, Jennifer Butler, Mokete Kaogo, Alistair Blair and Marcel du Plessis give an honours student's perspective on life on the SA Agulhas II.Academy of Science of South Africa: Department of Science and Innovatio
I remember teaching English at Seabrook
No full textIn this "I remember" memoir, Isabell Waugh, a former teacher at Seabrook, compares and constrasts the different groups of students she taught. She remembers that native-born American teenagers tended to be more concerned with athletics and social activities, than academic matters. In comparison, Estonian and Japanese parents did not tolerate low academic performance, so students from the two groups often competed intensely with each other for academic achievement and recognition. Isabelle recalls that the Estonians were, in general, more sophisticated and better educated. Most of the children knew 3-5 languages, and were more advanced in math and science. She sensed that some Estonian parents felt that their homes at Seabrook were temporary, and that they would be returning to Estonia at some point. The Seabrook Educational and Cultural Center has been soliciting current and past residents of Seabrook Farms for an "I remember" project. Residents are asked to create narratives regarding their experiences at Seabrook Farms. These memories help preserve the history and multi-cultural heritage of Seabrook Farms
Thermohaline variability of AAIW in the Atlantic sector of the Southern Ocean investigated using an Altimetry Gravest Empirical Mode
No full textThe southeast Atlantic sector of the Southern Ocean connects the Atlantic with the Indian Ocean and the Antarctic Circumpolar Current, thereby acting as a major conduit within global ocean circulation. Thermohaline transports in this region are widely thought to have a critical influence on global climate. Yet magnitudes of the associated heat and salt content variations are poorly understood due to a lack of hydrographic observations and model limitations. An improved Gravest Empirical Mode (GEM) is set up for the Southern Ocean south of Africa using the updated store of hydrographic measurements obtained from CTD transects for the area, combined with the available Argo profiles sampled in the region. Satellite altimetry is combined with the GEM relationships to create an Altimetry GEM (AGEM), thereby generating 20 years of temperature and salinity fields. These thermohaline sections for the region of the ocean south of Africa are found to be proficient at reproducing observations, with associated RMS errors being two orders of magnitude smaller than those reported by other comparable Southern Ocean GEM studies. Confident in the accuracy of the AGEM produced fields, an examination of the temporal evolution of Antarctic Intermediate Water (AAIW) is undertaken. The fluctuation and trends in heat and salt content anomalies and budgets is presented for each Southern Ocean frontal zone, along with the examination of the change in position of the isopycnal limits and resultant water mass thickness. So as to better understand one of the factors that may be influencing some of the changes detected within AAIW, property alterations of eddies identified in the region from 1992 to 2010 are investigated. A general decrease in magnitude and frequency of cyclones, coupled with an increase in absolute dynamic topography (ADT) of anticyclones, designates elevated injection of warm, saline water into the area. The connection identified between eddy property variations and AAIW modification in the region of the ocean south of Africa indicates that the water mass experiences ventilation with the mixed layer at latitudes further north than previously thought to occur. Obtaining an improved image of the magnitudes and variability of AAIW thermohaline properties in the Atlantic sector of the Southern Ocean greatly improves our understanding of its role in the ocean-climate system
Isabelle Bell to Susan Niemcewicz, December 23, 1800
No full textIsabelle Bell wrote to Susan U. Niemcewicz in Elizabethtown, New Jersey. Bell expressed her disappointment in not receiving a line from Susan. She sent Bell Lucretia Rephans subscription epistle, but Susan refrained from writing a letter to her. Bell did not execute any of Susan’s commissions in New York because her time there was short. Miss Resham heard that Mr. B Livingston told his sister, Mrs. J. Livingston that he would offer Bell a salary to live in his house and take charge of his children’s education. Asked if Susan what she thought of her being an author and if Susan would subscribe to a small volume that may have the good fortune to rival the poems of the immortal Scarron.https://digitalcommons.kean.edu/lhc_1800s/1143/thumbnail.jp
Decay of eddies at the South-West Indian Ridge
No full textThe South-West Indian Ridge in the Indian sector of the Southern Ocean is a region recognised for the creation of particularly intense eddy disturbances in the mean flow of the Antarctic Circumpolar Current. Eddies formed at this ridge have been extensively studied over the past decade using hydrographic, satellite, drifter and float data and it is hypothesised that they could provide a vehicle for localised meridional heat and salt exchange. The effectiveness of this process is dependent on the rate of decay of the eddies. However, in order to investigate eddy decay, logistically difficult hydrographic monitoring is required. This study presents the decay of cold eddies at the South-West Indian Ridge, using outputs from a high-resolution ocean model. The model’s representation of the dynamic nature of this region is fully characteristic of observations. On average, 3–4 intense and well-defined cold eddies are generated per year; these eddies have mean longevities of 5.0±2.2 months with average advection speeds of 5±2 km/day. Most simulated eddies reach their peak intensity within 1.5–2.5 months after genesis and have depths of 2000 m – 3000 m. Thereafter they dissipate within approximately 3 months. The decay of eddies is generally characterised by a decrease in their sea surface height signature, a weakening in their rotation rates and a modification in their temperature–salinity characteristics. Subantarctic top predators are suspected to forage preferentially along the edges of eddies. The process of eddy dissipation may thus influence their feeding behaviour
Interviews with Carl T. Bode, Isabelle Fritschen, Joseph H. Hirt, Mary G. Hirt, and Minnie Campbell
No full textInterviews with Carl T. Bode, Isabelle Fritschen, Joseph H. Hirt, Mary G. Hirt, and Minnie Campbell. The recording includes a variety of German-language songs. The last half of the recording is dedicated to Minnie Campbell telling about her time working for Mother Bickerdyke. The first few minutes of the recording are missing. 00:00:13 - Song, The Messenger Bird sung by Joseph H. Hirt and translated by Isabelle Fritschen 00:01:35 - Song, Birdie in the Window, sung by Mary Gertrude Hirt 00:02:59 - Story of Peter John Thielen\u27s experience in the Franco-Prussian War told by Joseph Hirt 00:05:27 - Grandfather\u27s experience with wild cattle told by Isabelle Fritschen 00:07:31 - Carl T. Bode introduction 00:08:46 - Nursery rhyme about hands 00:09:09 - The Cuckoo and the Donkey 00:09:42 - Sleep Baby Sleep 00:10:24 - Golden Evening Sun 00:11:00 - Beautiful Moon 00:12:10 - My Homeland 00:13:50 - Minnie Campbell Introduction 00:14:05 - Experiences as Mother Bickerdyke\u27s secretary 00:14:35 - Mother Bickerdyke\u27s 81st birthday celebration in Bunker Hill, KS 00:19:59 - Mother Bickerdyke\u27s portrait 00:23:55 - How Lydia Foster, Mother Bickerdyke\u27s Black maid came to live with her. 00:26:34 - Mother Bickerdyke\u27s death 00:29:34 - Mother Bickerdyke\u27s burial in Galesburg, Illinois 00:30:28 - Working for Mother Bickerdyke 00:34:01 - Going to School as a student of James Bickerdyke, Mother Bickerdyke\u27s son 00:35:26 - Decline of Bunker Hill, KS 00:37:15 - Russell stealing the county seat from Bunker Hill 00:38:09 - Closing of the Dorrance, KS bank 00:39:00 - Mother Bickerdyke\u27s personality 00:42:34 - Experience with Nina Brown Baker author of Cyclone in Calico 00:48:24 - Mother Bickerdyke Home for Widows and Children in Ellsworth, KS 00:51:13 - Post scripthttps://scholars.fhsu.edu/sackett/1014/thumbnail.jp
Evaluation of an eddy resolving HYCOM simulation in the South Atlantic Ocean
No full textIncludes bibliographical references.The South Atlantic Ocean acts as a key region of ocean teleconnections and water mass transformation, directly transporting waters from the Southern, Pacific and Indian Oceans towards the North Atlantic and feeding the upper branch of the Atlantic Meridional Overturning Circulation. To date, this region remains under sampled over long time periods. Models form useful platforms for the wholistic study of such regions where long term datasets are not available. However, it is important to first gauge to what extent the model deviates from available observations. In a detailed analysis, this study evaluates an eddy resolving 1/12° HYbrid Coordinate Ocean Model simulation in the South Atlantic and Agulhas regions with reference to available observations and literature. The outcomes of this research contribute to improving the configurations of future ocean models by identifying the limitations of the model analysed. In addition, analysis of the 50 year (1960-2009) simulation reveals that, in this model simulation, mesoscale activity and sea surface temperature trends in the Cape Basin are not related to Agulhas Current transport changes. These findings highlights the need for long term observational databases and further research into climate related trends and interannual variability of the ocean, in particular around Southern Africa
Formalization of Isabelle Meta Logic in NuPRL
No full textNuPRL and Isabelle are two general purpose theorem provers. Both of them are based on a version of Constructive Higher Order Type Theory. In an earlier work the author has proposed an informal semantics of Isabelle Meta Logic in an extension of NuPRL Type Theory. An automated converter, based on this semantics, has been developed, that translates Isabelle theorem statements into NuPRL. This work presents a formalization of the above semantics in NuPRL. It starts with a deep embedding of Isabelle type and term syntax into NuPRL Constructive Type Theory. Next, two internal NuPRL functions are defined. One of them maps Isabelle types into NuPRL types and the other maps Isabelle terms into elements of appropriate NuPRL types. These two functions provide an interpretation of Isabelle in NuPRL. Finally, interpretations of all Isabelle Meta Logic rules are proven as theorems in some classical extension of NuPRL Type Theory. This formalization is aimed to provide a more secure foundation for the interaction between two systems
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