2,410 research outputs found
Computed microtomography visualization and quantification of mouse ischemic brain lesion by nonionic radio contrast agents.
AIM:
To explore the possibility of brain imaging by microcomputed tomography (microCT) using x-ray contrasting methods to visualize mouse brain ischemic lesions after middle cerebral artery occlusion (MCAO). ----- METHODS:
Isolated brains were immersed in ionic or nonionic radio contrast agent (RCA) for 5 days and subsequently scanned using microCT scanner. To verify whether ex-vivo microCT brain images can be used to characterize ischemic lesions, they were compared to Nissl stained serial histological sections of the same brains. To verify if brains immersed in RCA may be used afterwards for other methods, subsequent immunofluorescent labeling with anti-NeuN was performed. ----- RESULTS:
Nonionic RCA showed better gray to white matter contrast in the brain, and therefore was selected for further studies. MicroCT measurement of ischemic lesion size and cerebral edema significantly correlated with the values determined by Nissl staining (ischemic lesion size: P=0.0005; cerebral edema: P=0.0002). Brain immersion in nonionic RCA did not affect subsequent immunofluorescent analysis and NeuN immunoreactivity. ----- CONCLUSION:
MicroCT method was proven to be suitable for delineation of the ischemic lesion from the non-infarcted tissue, and quantification of lesion volume and cerebral edema
Algorithmic Verification of Asynchronous Programs
Asynchronous programming is a ubiquitous systems programming idiom to manage
concurrent interactions with the environment. In this style, instead of waiting
for time-consuming operations to complete, the programmer makes a non-blocking
call to the operation and posts a callback task to a task buffer that is
executed later when the time-consuming operation completes. A co-operative
scheduler mediates the interaction by picking and executing callback tasks from
the task buffer to completion (and these callbacks can post further callbacks
to be executed later). Writing correct asynchronous programs is hard because
the use of callbacks, while efficient, obscures program control flow.
We provide a formal model underlying asynchronous programs and study
verification problems for this model. We show that the safety verification
problem for finite-data asynchronous programs is expspace-complete. We show
that liveness verification for finite-data asynchronous programs is decidable
and polynomial-time equivalent to Petri Net reachability. Decidability is not
obvious, since even if the data is finite-state, asynchronous programs
constitute infinite-state transition systems: both the program stack and the
task buffer of pending asynchronous calls can be potentially unbounded.
Our main technical construction is a polynomial-time semantics-preserving
reduction from asynchronous programs to Petri Nets and conversely. The
reduction allows the use of algorithmic techniques on Petri Nets to the
verification of asynchronous programs.
We also study several extensions to the basic models of asynchronous programs
that are inspired by additional capabilities provided by implementations of
asynchronous libraries, and classify the decidability and undecidability of
verification questions on these extensions.Comment: 46 pages, 9 figure
Parikh Image of Pushdown Automata
We compare pushdown automata (PDAs for short) against other representations.
First, we show that there is a family of PDAs over a unary alphabet with
states and stack symbols that accepts one single long word for
which every equivalent context-free grammar needs
variables. This family shows that the classical algorithm for converting a PDA
to an equivalent context-free grammar is optimal even when the alphabet is
unary. Moreover, we observe that language equivalence and Parikh equivalence,
which ignores the ordering between symbols, coincide for this family. We
conclude that, when assuming this weaker equivalence, the conversion algorithm
is also optimal. Second, Parikh's theorem motivates the comparison of PDAs
against finite state automata. In particular, the same family of unary PDAs
gives a lower bound on the number of states of every Parikh-equivalent finite
state automaton. Finally, we look into the case of unary deterministic PDAs. We
show a new construction converting a unary deterministic PDA into an equivalent
context-free grammar that achieves best known bounds.Comment: 17 pages, 2 figure
Impact of Workplace Stress on Job Satisfaction Moderated by Religious Coping
Workplace stress has been associated with negative job satisfaction outcomes, therefore leading employees to engage in coping strategies to minimize the consequences of the stressors. Although much research has been conducted on workplace stressors and their consequences, a small amount of literature exists on how women and Hispanics cope with workplace stressors or how people cope with the stressors in religious ways. To investigate the relationships among these factors, data was collected via an online survey completed by 268 university employees at a southwestern university. Self-report data collected suggested that both women and Hispanics use religion to cope with workplace stress more than men and non-Hispanics; however religious coping did not buffer the relationship between stressors and job satisfaction
Alfredo Baeschlin y la arquitectura popular vanguardista, Ibiza 1933-1934
El artículo pretende reflexionar sobre la casuística profesional y personal de Alfredo Baeschlin como paradigma de una época intrincada en el modo de entender la vida, las relaciones sociales y la profesión vinculada a la arquitectura como vía de aproximación entre la arquitectura tradicional y las corrientes arquitectónicas más vanguardistas. Para ello, se propone un análisis sobre lo que sucedió en Ibiza, isla conocida por sus flirteos con la modernidad, y escuela experimental, vital, emocional, idílica y utópica para intelectuales que buscaron un trance temporal que reordenara o aireara sus percepciones mediante una profunda inmersión en un mundo luminoso, espacioso y ancestral donde sólo algunos viajeros pudieron encontrar la inspiración rodeados del incomparable paisaje mediterráneo. El viaje y la experiencia cargaron de razones un mito al que muchos arquitectos recurrieron para investigar con el fin de comprender el presente y el futuro de una arquitectura popular vanguardista. El enfoque perceptivo, la imagen y el valor cultural fueron los encargados de reflexionar el ámbito arquitectónico de la época. (A
Are World Heritage concepts of integrity and authenticity lacking in dynamism? A critical approach to Mediterranean autotopic landscapes
This paper examines how contemporary on-going and lively debate on Critical Heritage Studies merges
with previous discourses on World Heritage Cultural Landscapes and rural societies. The scholarly
approach to authenticity and integrity, and the critical point of static and dynamic approaches to these terms
allow the author to challenge previous World Heritage (WH) discourses with a view to obtaining innovative
insight into abandoned vernacular landscapes. Two main arguments are thus developed in this study. The
first of these is an overview of the dynamics of abandoned cultural landscapes on an international scale.
The second is an inside view aiming to provide an accurate interpretation of how these landscapes should
be scrutinised and understood. To do this, autotopias and heterotopias broach the fundamental issue of how
the Outstanding Universal Value of attributes in abandoned cultural landscapes needs to be understood,
enhanced, experienced, and managed in an innovative WH approach. In conclusion, complex proposals for
these heritage landscapes should rely on understanding the dynamics of the material and the social construct
of the habitats they contain in order to assess them effectively from the standpoint of a World Heritage
Cultural process Assemblage rather than that of Outstanding Material Stratification
La valorización de la arquitectura vernácula. Claves históricas para el discurso actual
The article analyzes how vernacular architecture was valorized depending on the place, the cultural background and the external influences
in the late nineteenth and early twentieth century. The discourse relates Spain with Central European countries, those who were pioneers
in encouraging culture, traditions and pedagogy through a new way of observing and feeling the beauty of certain objects. As it will see,
eclectic views took place, from those who defended tradition, to those who viewed the weight of history as a burden detrimental to the
evolution and progress. In that sense, the intended approach on the modern perception of the traces of vernacular architecture is novel
because the topic is focused from the cultural and societal divergences from the different temporalities. The paper concludes the analysis
of the place and their traces by noticing their topicality with contemporary assessments on the vernacular architecture and society of the
different Cultural Environments.El artículo analiza cómo la arquitectura vernácula fue valorizada en función del lugar, el contexto cultural y las influencias externas a finales del siglo XIX y
principios del siglo XX. El discurso relaciona España con países de la Europa Central, pioneros en alentar la cultura, las tradiciones y la pedagogía a través
de una nueva forma de observar y sentir la belleza de ciertos objetos. El discurso analizará diferentes visiones eclécticas que tuvieron lugar, desde los que
defendían la tradición a los que consideraban el peso de la historia como una carga perjudicial para la evolución y el progreso. En ese sentido, el enfoque
pretendido hacia la percepción moderna de las trazas de la arquitectura vernácula es novedoso porque se centra en las diferencias culturales y sociales
de las distintas temporalidades. El documento concluye el análisis del lugar y sus trazas al denotar su actualidad referida a los estudios contemporáneos
sobre la arquitectura vernácula y la sociedad de los diferentes entornos culturales
Beyond the intangible/tangible binary: an analysis of historic built environments in Valencia
This paper is a theoretical reflection aiming to understand
how specific assets of intangible heritage are affected
by contemporary discourse. This approach focuses on
understanding the protection, preservation and reenactment of the intangible heritage found in Spanish
rural landscapes. By an analysis of the global, national
and regional laws, the paper addresses the need to
approach the intangible, understanding the peculiarities
of places that shape the scenery. The places and ‘Assets
of Cultural Interest’ analysed in this paper are defined
as geographic areas associated with a historic event,
activity, or people, which exhibit cultural and aesthetic
values. Following this definition, these landscapes are
experiential cultural spaces, involving a complex set of
elements, fixed, semi-fixed and unfixed. The way in which
these traditions are viewed and experienced by locals and
foreigners plays a central role in many intangible heritage
studies, as does the way in which it reflects integrity,
authenticity, attachment and a sense of identity, and how
it anchors collective memory. It is the intention of this paper
to emphasise the need to transfer the phenomenon of
intangible heritage from the realm of a lived experience
to the world of living places. In doing so some questions
arise: Is the intangible cultural heritage contained in
rural landscapes authentic? Is it simply the materiality,
the past act or the past cultural process, or is it the way
the intangible cultural heritage has been managed until
today? Are we applying critical considerations to inner and
outer perceptions, appropriations and transmigrations
when managing cultural heritage
Barracas on the Mediterranean Coast
A cultural heritage approach is used to present a scientific analysis of a traditional building method. A series of detailed monographs are referenced. The article discusses the Central European conservation theories of “Heimatschutz” at the beginning of the 20th century and the ideals of Krausism to determine a direct relationship between narrative art and photography as a threshold to the heritage analyzed. The study begins with a metric analysis of the barraca, a typical one-story thatched farmhouse in the Valencia area, and examines its construction and pathology; the study reviews the construction's constituent parts through schematic illustrations to offer a greater understanding of its creation and subsequent processes of transformation. The study departs from the strict reinterpretation of traditional building techniques to adopt an approach that examines the use of its component materials, thus providing an understanding of interventions that are compatible with conservation
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