1,521 research outputs found
Low Rank Vector Bundles on the Grassmannian G(1,4)
Here we define the concept of -regularity for coherent sheaves on the
Grassmannian G(1,4) as a generalization of Castelnuovo-Mumford regularity on
. In this setting we prove analogs of some classical properties. We
use our notion of -regularity in order to prove a splitting criterion for
rank 2 vector bundles with only a finite number of vanishing conditions. In the
second part we give the classification of rank 2 and rank 3 vector bundles
without "inner" cohomology (i.e. H^i_*(E)=H^i(E\otimes\Q)=0 for any
) on G(1,4) by studying the associated monads.Comment: 11 pages, no figure
Proliferation of metallic domains caused by inhomogeneous heating near the electrically-driven transition in VO nanobeams
We discuss the mechanisms behind the electrically driven insulator-metal
transition in single crystalline VO nanobeams. Our DC and AC transport
measurements and the versatile harmonic analysis method employed show that
non-uniform Joule heating causes phase inhomogeneities to develop within the
nanobeam and is responsible for driving the transition in VO. A
Poole-Frenkel like purely electric field induced transition is found to be
absent and the role of percolation near and away from the electrically driven
transition in VO is also identified. The results and the harmonic
analysis can be generalized to many strongly correlated materials that exhibit
electrically driven transitions
Cambio y restauración del hábitat: respuestas de una especie de mamíferos del suelo forestal a las manipulaciones de los árboles caídos en bosques inundados
In forests and woodlands, fallen timber (logs and large branches) is an important habitat element for many species of animals. Fallen timber has been systematically stripped in many forests, eliminating an important structural element. This study describes results of a "meso–scale" experiment in which fallen timber was manipulated in a floodplain forest of the Murray River in south–eastern Australia. A thousand tons of wood were redistributed after one–year’s pre–manipulation monitoring, while a further two–year's post–manipulation monitoring was conducted. The response of the main forest–floor small–mammal species, the Yellow–footed Antechinus Antechinus flavipes, to alterations of fallen–wood loads is documented. Results of the experiment will help to frame guidelines for fallen–timber management in these extensive floodplain forests.En los bosques y montes los árboles caídos (troncos y ramas gruesas) constituyen un importante elemento del hábitat para muchas especies de animales. Los árboles caídos han sido sistemáticamente descortezados en muchos bosques, eliminándose así un importante elemento estructural. Este estudio describe resultados de un experimento a escala mediana en el que los árboles caídos fueron manipulados en un bosque inundado del río Murray, en el sureste de Australia. Se redistribuyeron 1.000 toneladas de madera después de efectuar un control previo a la manipulación durante un año, realizándose otro control durante dos años después de la manipulación. Se documenta la respuesta de la especie de mamífero del suelo del bosque, el ratón marsupial de pies amarillos Antechinus flavipes, a las alteraciones de la madera caída. Los resultados de este trabajo pueden servir de ayuda para elaborar unas directrices marco para la gestión de los árboles caídos en bosques inundados
"Where is the protocol?” Independent thinking increases student engagement in laboratory work:a case study
Laboratory work plays a central role in the training of students in the process of science. In a typical laboratory class students are presented with a robust protocol and perform experiments where the results are predetermined. This expository style of teaching (as defined by Domin 1999) is commonly used in many institutions (including our own). Activities are designed so that large numbers of students can carry out the same experiment at low cost in a two to three hour time frame. These laboratories are often viewed as “recipe following” or “cookbook” exercises with low cognitive demands (Tobin 1987). The students are not required to plan the investigation and so often attend sessions with little planning and preparation. During the laboratory the focus is on obtaining the “right result”. Assessment of lab work is usually via the submission of a report where primacy is given to the fundamental science the exercise was designed to explore as opposed to how to design and execute experiments. The benefits of enquiry and problem based laboratory sessions in teaching the scientific process has been widely discussed (Waldrop 2015) and this case study presents an approach to introducing this type of delivery into a BSc Biomedical Sciences programme
Developing an inquiry-based learning module with consideration of quality by design principles for biomedical science students
To help students develop into confident and effective laboratory scientists it is necessary to facilitate their understanding and ability to participate effectively in all processes involved in experimental design and implementation in an engaging and realistic manner. Our challenge was to develop a 20-credit, ordinary degree (without honours) level, practical skills-based module for Biomedical Science students who are not on a National Health Service placement that encompasses elements of professionalism. We describe the design of a module that utilises Inquiry-based learning (IBL) and Quality by Design (QbD) principles and discuss staff experience and reflections following analysis of six years of anonymised module feedback data which includes quantitative and qualitative data. Key positive themes from the qualitative analysis were satisfaction at being able to make evidenced based decisions for changes in experimental factors and development of personal skills which was perceived as helpful for their preparation for their honours year project. The level of challenge that the format of the module presented was perceived negatively. We conclude that this mode of learning is challenging to implement and monitor for academics and challenges students intellectual and professional development, but that the benefits are worth the investment
Reasoning with Very Expressive Fuzzy Description Logics
It is widely recognized today that the management of imprecision and
vagueness will yield more intelligent and realistic knowledge-based
applications. Description Logics (DLs) are a family of knowledge representation
languages that have gained considerable attention the last decade, mainly due
to their decidability and the existence of empirically high performance of
reasoning algorithms. In this paper, we extend the well known fuzzy ALC DL to
the fuzzy SHIN DL, which extends the fuzzy ALC DL with transitive role axioms
(S), inverse roles (I), role hierarchies (H) and number restrictions (N). We
illustrate why transitive role axioms are difficult to handle in the presence
of fuzzy interpretations and how to handle them properly. Then we extend these
results by adding role hierarchies and finally number restrictions. The main
contributions of the paper are the decidability proof of the fuzzy DL languages
fuzzy-SI and fuzzy-SHIN, as well as decision procedures for the knowledge base
satisfiability problem of the fuzzy-SI and fuzzy-SHIN
Combinatorial Games with a Pass: A dynamical systems approach
By treating combinatorial games as dynamical systems, we are able to address
a longstanding open question in combinatorial game theory, namely, how the
introduction of a "pass" move into a game affects its behavior. We consider two
well known combinatorial games, 3-pile Nim and 3-row Chomp. In the case of Nim,
we observe that the introduction of the pass dramatically alters the game's
underlying structure, rendering it considerably more complex, while for Chomp,
the pass move is found to have relatively minimal impact. We show how these
results can be understood by recasting these games as dynamical systems
describable by dynamical recursion relations. From these recursion relations we
are able to identify underlying structural connections between these "games
with passes" and a recently introduced class of "generic (perturbed) games."
This connection, together with a (non-rigorous) numerical stability analysis,
allows one to understand and predict the effect of a pass on a game.Comment: 39 pages, 13 figures, published versio
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