The dispersal versus vicariance debate in biogeography

Bothalia ◽  
1983 ◽  
Vol 14 (3/4) ◽  
pp. 455-460 ◽  
Author(s):  
J. C. Poynton
Keyword(s):  
The Past ◽  
Residual Fragment ◽  
History Of

Wild’s 1964 study of the Chimanimani Mountain endemics is taken as an example of a vicariance model: endemics (1) are seen to have originated in situ from a residual fragment of an ancestral, once-continuous flora; (2) are held to present in themselves no history of major dispersal; and consequently a biogeographical intrepretation involving or presupposing their ‘migrations' is not thought to be applicable. The preference Wild expressed for this model over a dispersalist model attributed to Levyns is investigated, making use of theoretical refinements developed in the dispersal vs vicariance debate within the past decade. The differences in intrepretations between Wild and Levyns appear to be unresolvable on account of their positions not being demarcated clearly enough, and the situation has not improved since then, underlining the need for attention to be given to the formulation of applicable, coherent and testable hypotheses in biogeography.

scholarly journals Up Close and Personal: Feeling the Past at Urban Archaeological Sites

2016 ◽  
Vol 23 ◽  
pp. 43-55 ◽  
Author(s):  
Tracy Ireland
Keyword(s):  
Archaeological Sites ◽  
Colonial History ◽  
Archaeological Remains ◽  
Complex Matrix ◽  
Social Emotional ◽  
The Past ◽  
History Of ◽  
Personal Feeling ◽  
The City

In this article I focus on the emotional, sensory and aesthetic affordances of urban archaeological remains conserved in situ and explore what these ruins ‘do’ in the context of the layered urban fabric of the city. I am concerned with a particular category of archaeological remains: those that illustrate the colonial history of settler nations, exploring examples in Sydney and Montreal. Using Sara Ahmed’s concept of ‘affective economies’ – where emotions work to stick things together and align individuals with communities – I tease out some of the distinctive aspects of this particular form of social/emotional/material entanglement, that appears to create stable objects of memory and identity from a much more contingent and complex matrix of politics, social structures, and the more-than-human materiality of the city. I argue that an understanding of the affective qualities of ruins and archaeological traces, and of how people feel heritage and the past through aesthetic and sensuous experiences of materiality, authenticity, locality and identity, bring us closer to understanding how heritage works. 

Reconstructing the star formation history of the Solar neighbourhood with Gaia

2017 ◽  
Vol 13 (S334) ◽  
pp. 158-161
Author(s):  
Edouard J. Bernard
Keyword(s):  
Star Formation ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Star Formation History ◽  
Solar Neighbourhood ◽  
The Past ◽  
Formation History ◽  
Magnitude Diagram ◽  
History Of

AbstractTaking advantage of the Gaia DR1, we combined TGAS parallaxes with the Tycho-2 and APASS photometry to calculate the star formation history (SFH) of the solar neighbourhood within 250 pc using the colour-magnitude diagram fitting technique. Our dynamically-evolved SFH is in excellent agreement with that calculated from the Hipparcos catalogue within 80 pc of the Sun, showing an enhanced star formation rate (SFR) in the past ~4 Gyr. We then correct the SFR for the disc thickening with age to obtain a SFR that is representative of the whole solar cylinder, and show that even with an extreme correction our results are not consistent with an exponentially decreasing SFR as found by recent studies. Finally, we discuss how this technique can be applied out to ~5 kpc thanks to the next Gaia data releases, which will allow us to quantify the SFH of the thin disc, thick disc and halo in situ.

scholarly journals A Unique Case of Testicular Compromise in a Patient with Ovotesticular Disorder of Sexual Development and a Solitary Testicle

2017 ◽  
Vol 2017 ◽  
pp. 1-3
Author(s):  
Ethan Vargo ◽  
Lillianne Stanitsas ◽  
Mark Memo
Keyword(s):  
Sexual Development ◽  
Ovarian Tissue ◽  
Prior History ◽  
Unique Case ◽  
The Past ◽  
Vascular Flow ◽  
Disorder Of Sexual Development ◽  
Increased Risk ◽  
History Of

Ovotesticular disorder of sexual development (OT-DSD), previously true hermaphroditism, is a condition in which one or both gonads contain testicular and ovarian tissue. A 23-year-old OT-DSD male patient presented with continuous pain in his right testicle which had been previously intermittent over the past five days. The patient had a prior history of left ovotestis removal with prosthesis placement, a right undescended testicle with aberrant anatomy, and hypospadias repair, all of which were corrected shortly after birth. A lack of blood flow to the testicle on Doppler ultrasound warranted immediate surgical intervention. Intraoperatively, an aberrant tunica vaginalis space with a compressive hematoma secondary to epididymal abscess rupture was identified as the causation for testicular compromise. Return of vascular flow to the testicle was confirmed with intraoperative Doppler after hematoma and epididymis excision, and the testicle was left in situ. It is imperative to consider epididymal etiologies with acute testicular pain, especially in a patient with a medical history that carries an increased risk for gonadal anomalies.

scholarly journals Watermills and windmills as monuments in Poland - protection of cultural heritage in situ and in open-air museums

2020 ◽  
Vol 8 (3) ◽  
pp. 41-62
Author(s):  
Zachariasz Mosakowski ◽  
Dariusz Brykała ◽  
Maciej Prarat ◽  
Daria Jagiełło ◽  
Zbigniew Podgórski ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Cultural Heritage ◽  
Important Task ◽  
National Register ◽  
The Past ◽  
History Of ◽  
Nineteenth And Twentieth Centuries ◽  
Protection Of Cultural Heritage

This paper presents the results of research on the history of the protection of mills as objects of cultural heritage on Polish lands. First, the spatial distribution of over 20,000 mills at the beginning of the previous century is characterized, then the main actions undertaken for their protection in the nineteenth and twentieth centuries are discussed. Merely 3.4% of mills that worked in the past are now protected as monuments and recorded in the national register. Most of them remain in their original locations (in situ), and another 71 windmills and 22 watermills have been relocated to open-air museums. These specific institutions face a particularly important task involving the necessity to retain the original functionality of the mills.

On The Possibility of an Autonomous History of Modern Southeast Asia

1961 ◽  
Vol 2 (2) ◽  
pp. 73-105 ◽  
Author(s):  
John R. W. Small
Keyword(s):  
Southeast Asia ◽  
Contemporary History ◽  
The Past ◽  
History Of

It is generally accepted that history is an element of culture and the historian a member of society, thus, in Croce's aphorism, that the only true history is contemporary history. It follows from this that when there occur great changes in the contemporary scene, there must also be great changes in historiography, that the vision not merely of the present but also of the past must change.

Stellar Evolution

1962 ◽  
Vol 11 (02) ◽  
pp. 137-143
Author(s):  
M. Schwarzschild
Keyword(s):  
Solar System ◽  
Stellar Evolution ◽  
Space Craft ◽  
New Techniques ◽  
Substantial Body ◽  
Individual Stars ◽  
The Past ◽  
Evolution Of Galaxies ◽  
History Of ◽  
Fast Flow

It is perhaps one of the most important characteristics of the past decade in astronomy that the evolution of some major classes of astronomical objects has become accessible to detailed research. The theory of the evolution of individual stars has developed into a substantial body of quantitative investigations. The evolution of galaxies, particularly of our own, has clearly become a subject for serious research. Even the history of the solar system, this close-by intriguing puzzle, may soon make the transition from being a subject of speculation to being a subject of detailed study in view of the fast flow of new data obtained with new techniques, including space-craft.

The Use of Advanced Analytical Techniques for Characterization of the Chemical, Physical, and Crystallographic Nature of a Surface

1973 ◽  
Vol 31 ◽  
pp. 132-133 ◽  
Author(s):  
R. E. Herfert
Keyword(s):  
Surface Characterization ◽  
Analytical Techniques ◽  
X Ray Diffraction ◽  
Depth Of Penetration ◽  
X Ray ◽  
The Past ◽  
Transmission Electron ◽  
Scanning Electron

Studies of the nature of a surface, either metallic or nonmetallic, in the past, have been limited to the instrumentation available for these measurements. In the past, optical microscopy, replica transmission electron microscopy, electron or X-ray diffraction and optical or X-ray spectroscopy have provided the means of surface characterization. Actually, some of these techniques are not purely surface; the depth of penetration may be a few thousands of an inch. Within the last five years, instrumentation has been made available which now makes it practical for use to study the outer few 100A of layers and characterize it completely from a chemical, physical, and crystallographic standpoint. The scanning electron microscope (SEM) provides a means of viewing the surface of a material in situ to magnifications as high as 250,000X.

In situ microprobe quantitation of inorganic particle burden in paraffin sections of lung tissue

1988 ◽  
Vol 46 ◽  
pp. 990-991
Author(s):  
Jerrold L. Abraham
Keyword(s):  
Lung Tissue ◽  
Quantitative Information ◽  
Particulate Material ◽  
Paraffin Sections ◽  
Tissue Samples ◽  
Qualitative And Quantitative ◽  
The Past ◽  
Quantitative Analyses ◽  
Data Result

Inorganic particulate material of diverse types is present in the ambient and occupational environment, and exposure to such materials is a well recognized cause of some lung disease. To investigate the interaction of inhaled inorganic particulates with the lung it is necessary to obtain quantitative information on the particulate burden of lung tissue in a wide variety of situations. The vast majority of diagnostic and experimental tissue samples (biopsies and autopsies) are fixed with formaldehyde solutions, dehydrated with organic solvents and embedded in paraffin wax. Over the past 16 years, I have attempted to obtain maximal analytical use of such tissue with minimal preparative steps. Unique diagnostic and research data result from both qualitative and quantitative analyses of sections. Most of the data has been related to inhaled inorganic particulates in lungs, but the basic methods are applicable to any tissues. The preparations are primarily designed for SEM use, but they are stable for storage and transport to other laboratories and several other instruments (e.g., for SIMS techniques).

An atomic-resolution microscope study of Al contracts on GaAs

1986 ◽  
Vol 44 ◽  
pp. 726-727
Author(s):  
Z. Liliental-Weber ◽  
C. Nelson ◽  
R. Ludeke ◽  
R. Gronsky ◽  
J. Washburn
Keyword(s):  
High Speed ◽  
Schottky Contacts ◽  
Detailed Knowledge ◽  
The Past ◽  
Semiconductor Interfaces ◽  
Deposited Metal ◽  
Microwave Applications ◽  
Free Interfaces ◽  
Potential Use

The properties of metal/semiconductor interfaces have received considerable attention over the past few years, and the Al/GaAs system is of special interest because of its potential use in high-speed logic integrated optics, and microwave applications. For such materials a detailed knowledge of the geometric and electronic structure of the interface is fundamental to an understanding of the electrical properties of the contact. It is well known that the properties of Schottky contacts are established within a few atomic layers of the deposited metal. Therefore surface contamination can play a significant role. A method for fabricating contamination-free interfaces is absolutely necessary for reproducible properties, and molecularbeam epitaxy (MBE) offers such advantages for in-situ metal deposition under UHV conditions

A 200-Year History of the Study of Childhood Language Disorders of Unknown Origin: Changes in Terminology

2020 ◽  
Vol 5 (1) ◽  
pp. 6-11 ◽  
Author(s):  
Laurence B. Leonard
Keyword(s):  
Language Impairment ◽  
Specific Language Impairment ◽  
Scientific Literature ◽  
Language Disorder ◽  
Language Disorders ◽  
Unknown Origin ◽  
Developmental Language Disorder ◽  
The Past ◽  
History Of ◽  
The Many

Purpose The current “specific language impairment” and “developmental language disorder” discussion might lead to important changes in how we refer to children with language disorders of unknown origin. The field has seen other changes in terminology. This article reviews many of these changes. Method A literature review of previous clinical labels was conducted, and possible reasons for the changes in labels were identified. Results References to children with significant yet unexplained deficits in language ability have been part of the scientific literature since, at least, the early 1800s. Terms have changed from those with a neurological emphasis to those that do not imply a cause for the language disorder. Diagnostic criteria have become more explicit but have become, at certain points, too narrow to represent the wider range of children with language disorders of unknown origin. Conclusions The field was not well served by the many changes in terminology that have transpired in the past. A new label at this point must be accompanied by strong efforts to recruit its adoption by clinical speech-language pathologists and the general public.

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