Relationship of simultaneous atrial and ventricular pressures in stage 16-27 chick embryos

1995 ◽  
Vol 269 (4) ◽  
pp. H1359-H1362 ◽  
Author(s):  
N. Hu ◽  
B. B. Keller
Keyword(s):  
Diastolic Pressure ◽  
Dynamic Balance ◽  
Cellular Tissue ◽  
Pressure Gradients ◽  
Endocardial Cushions ◽  
Mean Pressure ◽  
And Function ◽  
A Site ◽  
Relationship Of ◽  
Ventricular Filling

Ventricular filling is determined by a dynamic balance between atrial and ventricular load and function. The embryonic cardiovascular system undergoes simultaneous growth and morphogenesis at the cellular, tissue, and organ levels to match the embryo's geometrically increasing metabolic demands. As part of our long-term investigation of atrial/ventricular coupling during primary cardiac morphogenesis, we defined the relationship between simultaneous atrial and ventricular pressures in the stage 16-27 white Leghorn chick embryo. We measured atrial and ventricular blood pressures with servo-null micropressure systems and sampled analog waveforms digitally at 500 Hz. Peak atrial pressure increased geometrically from 0.38 +/- 0.03 to 1.21 +/- 0.17 mmHg, while ventricular end-diastolic pressure increased linearly from 0.18 +/- 0.03 to 0.55 +/- 0.04 mmHg. The passive and active mean pressure gradients increased from 0.23 +/- 0.04 and 0.20 +/- 0.03 mmHg at stage 16 to 0.52 +/- 0.10 and 0.62 +/- 0.11 mmHg at stage 27, respectively. The atrioventricular pressure gradients were similar for stages 16, 18, and 21, then increased to stage 27. This diastolic pressure gradient identifies the atrioventricular orifice and developing endocardial cushions as a site of flow resistance that may influence both ventricular filling and chamber morphogenesis.

Haemodynamics in Tresus Nuttallii and Certain other Bivalves

1965 ◽  
Vol 43 (1) ◽  
pp. 171-180
Author(s):  
L. S. SMITH ◽  
J. C. DAVIS
Keyword(s):  
Sea Water ◽  
Diastolic Pressure ◽  
Isolated Heart ◽  
Aortic Pressure ◽  
The Body ◽  
Blood Pressures ◽  
A Site ◽  
Control Direction ◽  
Ventricular Filling ◽  
Morphology Of The Heart

1. Blood pressures were measured in the hearts and aortas of several bivalves. 2. Systolic pressures in the ventricles were commonly 0·5-2·0 mm. Hg, while diastolic pressure was zero. 3. The aortic bulb produced pressures similar to those produced by the ventricle, but beat less frequently and not in synchrony with the ventricle, except in the isolated heart. 4. Pericardial and auricular pressures were normally undetectable, except that small pressure pulses were recorded in the auricle during experimentally produced increases in venous return. 5. Aortic pressure sometimes exceeded ventricular pressure, although unusually strong contractions of the body muscles raised aortic pressures far above that in the ventricle. The heart does not provide pressure for extension of siphons or foot. 6. Sea water pumped by isolated Tresus ventricles demonstrated that neither pericardium nor auricles are needed for ventricular filling, as had been hypothesized earlier. 7. The morphology of the heart walls supports the concept of bivalve hearts as being a site of filtration, with the ventricle thought to play a larger role than the auricles. 8. Valves in the heart and aortas which control direction of blood flow are described.

Colonialism and the Highland Clearances

2017 ◽  
Vol 8 (1) ◽  
pp. 22-48 ◽  
Author(s):  
Iain Mackinnon
Keyword(s):  
Industrial Development ◽  
Comparative Approach ◽  
Indigenous Research ◽  
Internal Colonialism ◽  
New Approach ◽  
A Site ◽  
Relationship Of ◽  
The Relationship ◽  
Imperial State ◽  
Late Modern

This article employs a new approach to studying internal colonialism in northern Scotland during the 18th and 19th centuries. A common approach to examining internal colonial situations within modern state territories is to compare characteristics of the internal colonial situation with attested attributes of external colonial relations. Although this article does not reject the comparative approach, it seeks to avoid criticisms that this approach can be misleading by demonstrating that promoters and managers of projects involving land use change, territorial dispossession and industrial development in the late modern Gàidhealtachd consistently conceived of their work as projects of colonization. It further argues that the new social, cultural and political structures these projects imposed on the area's indigenous population correspond to those found in other colonial situations, and that racist and racialist attitudes towards Gaels of the time are typical of those in colonial situations during the period. The article concludes that the late modern Gàidhealtachd has been a site of internal colonization where the relationship of domination between colonizer and colonized is complex, longstanding and occurring within the imperial state. In doing so it demonstrates that the history and present of the Gaels of Scotland belongs within the ambit of an emerging indigenous research paradigm.

Asking More than Where: Developing a Site Contextual Model Based on Reconstructing past Environments

1997 ◽  
Vol 17 (4) ◽  
pp. 307-336
Author(s):  
Douglas S. Frink
Keyword(s):  
Native American ◽  
Phase I ◽  
Contextual Model ◽  
Model Based ◽  
European Settlement ◽  
Level Data ◽  
Limited Application ◽  
And Function ◽  
A Site ◽  
Phase Ii And Iii

Contract archaeology accounts for the majority of archaeological studies conducted in Vermont. As these studies serve the development community, the focus of investigation has been to identify and avoid sites, not to research and evaluate the information they contain. Native-American site locational models have limited application because they are based primarily on the landforms' proximity to water. The Archaeology Consulting Team is developing a contextual model based on reconstructing the pre-European settlement environment. Hypotheses comparing expected size and function of Native-American sites in different environments can be posed at the Phase I level of archaeological studies. Furthermore, with Phase I level data, these hypotheses can provide the framework for research designs at Phase II and III levels of archaeological study.

The Documentary Imagination in Twentieth-Century French Literature

2020 ◽  
Author(s):  
Alison James
Keyword(s):  
Twentieth Century ◽  
French Literature ◽  
Literary Work ◽  
Visual Media ◽  
Visual Evidence ◽  
Current Events ◽  
Twentieth Century French Literature ◽  
A Site ◽  
Relationship Of ◽  
The Relationship

This book studies the documentary impulse that plays a central role in twentieth-century French literature. Focusing on nonfiction narratives, it analyzes the use of documents—pieces of textual or visual evidence incorporated into the literary work to relay and interrogate reality. It traces the emergence of an enduring concern with factual reference in texts that engage with current events or the historical archive. Writers idealize the document as a fragment of raw reality, but also reveal its constructed and mediated nature and integrate it as a voice within a larger composition. This ambivalent documentary imagination, present in works by Gide, Breton, Aragon, Yourcenar, Duras, and Modiano (among others), shapes the relationship of literature to visual media, testimonial discourses, and self-representation. Far from turning away from realism in the twentieth century, French literature often turns to the document as a site of both modernist experiment and engagement with the world.

scholarly journals What Happened to Your College Town: The Changing Relationship of Higher Education and College Towns, 1940–2000

2021 ◽  
Vol 61 (3) ◽  
pp. 320-340
Author(s):  
Kate Rousmaniere
Keyword(s):  
Higher Education ◽  
Higher Education Institutions ◽  
History Of Higher Education ◽  
Campus Housing ◽  
College Towns ◽  
Education Enrollment ◽  
History Of ◽  
To Come ◽  
And Function ◽  
Relationship Of

AbstractThis essay examines the history of what is commonly called the town-gown relationship in American college towns in the six decades after the Second World War. A time of considerable expansion of higher education enrollment and function, the period also marks an increasing detachment of higher education institutions from their local communities. Once closely tied by university offices that advised the bulk of their students in off-campus housing, those bonds between town and gown began to come apart in the 1970s, due primarily to legal and economic factors that restricted higher education institutions’ outreach. Given the importance of off-campus life to college students, over half of whom have historically lived off campus, the essay argues for increased research on college towns in the history of higher education.

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