scholarly journals Sarcopterygian fin ontogeny elucidates the origin of hands with digits

2020 ◽  
Vol 6 (34) ◽  
pp. eabc3510
Author(s):  
Joost M. Woltering ◽  
Iker Irisarri ◽  
Rolf Ericsson ◽  
Jean M. P. Joss ◽  
Paolo Sordino ◽  
...  
Keyword(s):  
Developmental Patterns ◽  
Classical Models ◽  
Specific Expansion ◽  
Fish Fins ◽  
Fin Development ◽  
Australian Lungfish

How the hand and digits originated from fish fins during the Devonian fin-to-limb transition remains unsolved. Controversy in this conundrum stems from the scarcity of ontogenetic data from extant lobe-finned fishes. We report the patterning of an autopod-like domain by hoxa13 during fin development of the Australian lungfish, the most closely related extant fish relative of tetrapods. Differences from tetrapod limbs include the absence of digit-specific expansion of hoxd13 and hand2 and distal limitation of alx4 and pax9, which potentially evolved through an enhanced response to shh signaling in limbs. These developmental patterns indicate that the digit program originated in postaxial fin radials and later expanded anteriorly inside of a preexisting autopod-like domain during the evolution of limbs. Our findings provide a genetic framework for the transition of fins into limbs that supports the significance of classical models proposing a bending of the tetrapod metapterygial axis.

scholarly journals Development of the caudal-fin skeleton reveals multiple convergent fusions within Atherinomorpha

2021 ◽  
Vol 18 (1) ◽  
Author(s):  
Philipp Thieme ◽  
Peter Warth ◽  
Timo Moritz
Keyword(s):  
Common Ancestor ◽  
Morphological Structure ◽  
Last Common Ancestor ◽  
Complex Structures ◽  
Caudal Fin ◽  
Developmental Patterns ◽  
Valuable Source ◽  
Similarities And Differences ◽  
Source Of Information ◽  
Fin Development

Abstract Background The caudal fin of teleosts is a highly diverse morphological structure and a valuable source of information for comparative analyses. Within the Atherinomorpha a high variation of conditions of the caudal-fin skeleton can be found. These range from complex but basal configurations to simple yet derived configurations. When comparing atherinomorph taxa, it is often difficult to decide on the homology of skeletal elements if only considering adult specimens. However, observing the development of caudal-fin skeletons allows one to evaluate complex structures, reveal homologies and developmental patterns, and even reconstruct the grundplan of the examined taxa. Results We studied the development of the caudal-fin skeleton in different atheriniform, beloniform and cyprinodontiform species using cleared and stained specimens. Subsequently we compared the development to find similarities and differences in terms of 1) which structures are formed and 2) which structures fuse during ontogeny. For many structures, i.e., the parhypural, the epural(s), the haemal and neural spines of the preural centra and the uroneural, there were either no or only minor differences visible between the three taxa. However, the development of the hypurals revealed a high variation of fusions within different taxa that partly occurred independently in atheriniforms, beloniforms and cyprinodontiforms. Moreover, comparing the development of the ural centra exposed two ways of formation of the compound centrum: 1) in atheriniforms and the beloniforms Oryzias and Hyporhamphus limbatus two ural centra develop and fuse during ontogeny while 2) in cyprinodontiforms and Exocoetidae (Beloniformes) only a single ural centrum is formed during ontogeny. Conclusions We were able to reconstruct the grundplan of the developmental pattern of the caudal-fin skeleton of the Atheriniformes, Beloniformes and Cyprinodontiformes as well as their last common ancestors. We found two developmental modes of the compound centrum within the Atherinomorpha, i.e., the fusion of two developing ural centra in atheriniforms and beloniforms and the development of only one ural centrum in cyprinodontiforms. Further differences and similarities for the examined taxa are discussed, resulting in the hypothesis that the caudal-fin development of a last common ancestor to all atherinomorphs is very much similar to that of extant atheriniforms.

Do Children With Developmental Language Disorder (DLD) Have Difficulties With Interference Control, Visuospatial Working Memory, and Selective Attention? Developmental Patterns and the Role of Severity and Persistence of DLD

2020 ◽  
Vol 63 (9) ◽  
pp. 3036-3050
Author(s):  
Elma Blom ◽  
Tessel Boerma
Keyword(s):  
Working Memory ◽  
Selective Attention ◽  
Language Disorder ◽  
Typically Developing ◽  
Developmental Language Disorder ◽  
Visuospatial Working Memory ◽  
Interference Control ◽  
Developmental Patterns ◽  
Search Tasks ◽  
The Impact

Purpose Many children with developmental language disorder (DLD) have weaknesses in executive functioning (EF), specifically in tasks testing interference control and working memory. It is unknown how EF develops in children with DLD, if EF abilities are related to DLD severity and persistence, and if EF weaknesses expand to selective attention. This study aimed to address these gaps. Method Data from 78 children with DLD and 39 typically developing (TD) children were collected at three times with 1-year intervals. At Time 1, the children were 5 or 6 years old. Flanker, Dot Matrix, and Sky Search tasks tested interference control, visuospatial working memory, and selective attention, respectively. DLD severity was based on children's language ability. DLD persistence was based on stability of the DLD diagnosis. Results Performance on all tasks improved in both groups. TD children outperformed children with DLD on interference control. No differences were found for visuospatial working memory and selective attention. An interference control gap between the DLD and TD groups emerged between Time 1 and Time 2. Severity and persistence of DLD were related to interference control and working memory; the impact on working memory was stronger. Selective attention was unrelated to DLD severity and persistence. Conclusions Age and DLD severity and persistence determine whether or not children with DLD show EF weaknesses. Interference control is most clearly impaired in children with DLD who are 6 years and older. Visuospatial working memory is impaired in children with severe and persistent DLD. Selective attention is spared.

Simulation Tool for Assignment Models: SIMASI

2014 ◽  
Vol 13 (8) ◽  
pp. 4723-4728
Author(s):  
Pratiksha Saxena ◽  
Smt. Anjali
Keyword(s):  
Optimization Procedure ◽  
Simulation Tool ◽  
Optimization Strategy ◽  
Performance Measurements ◽  
Integrated Simulation ◽  
Assignment Model ◽  
Classical Models ◽  
Simulation Results ◽  
User Friendly ◽  
Assignment Models

In this paper, an integrated simulation optimization model for the assignment problems is developed. An effective algorithm is developed to evaluate and analyze the back-end stored simulation results. This paper proposes simulation tool SIMASI (Simulation of assignment models) to simulate assignment models. SIMASI is a tool which simulates and computes the results of different assignment models. This tool is programmed in DOT.NET and is based on analytical approach to guide optimization strategy. Objective of this paper is to provide a user friendly simulation tool which gives optimized assignment model results. Simulation is carried out by providing the required values of matrix for resource and destination requirements and result is stored in the database for further comparison and study. Result is obtained in terms of the performance measurements of classical models of assignment system. This simulation tool is interfaced with an optimization procedure based on classical models of assignment system. The simulation results are obtained and analyzed rigorously with the help of numerical examples. 

Sergio Leone

2020 ◽  
Author(s):  
Christian Uva
Keyword(s):  
National Identity ◽  
Political Interest ◽  
Current Events ◽  
Classical Models ◽  
Key Aspects ◽  
Sergio Leone

Spectacle, myth, fable. These are the main categories that have traditionally defined Sergio Leone’s cinematic production, but it is necessary to underline how much they are fueled by a profound, layered political interest. Leone’s cinema bears witness to a critical outlook both on the subjects it showcases and on its representational means. Far from any militancy and escaping ideological classifications, Leone’s perspective is problematic and unreconciled: it is grounded in the coexistence of different elements in a state of perennial productive tension and instability. The adjective “political” takes on a deeper meaning when it is used to denote the director’s ability to narrate and interpret key aspects of Italian national identity and history. The abstract quality of his production relies on an original use of different genres, particularly sword-and-sandal and the Spaghetti Western, which allowed Leone to insert frequent symbolic references to both history and then-current events. On the stylistic level, his constant disobedience to classical models and his need to revolutionize forms were motivated by an authorial desire to make films politically, though still within a conception of cinema as an industrial spectacle.

Contesting the City

2017 ◽  
Author(s):  
Christian D. Liddy
Keyword(s):  
Urban Politics ◽  
Low Countries ◽  
Late Medieval ◽  
Urban Citizenship ◽  
Town Government ◽  
Medieval Europe ◽  
Political Narrative ◽  
Classical Models ◽  
The Rich ◽  
The City

The political narrative of late medieval English towns is often reduced to the story of the gradual intensification of oligarchy, in which power was exercised and projected by an ever smaller ruling group over an increasingly subservient urban population. This book takes its inspiration not from English historiography, but from a more dynamic continental scholarship on towns in the southern Low Countries, Germany, and France. Its premise is that scholarly debate about urban oligarchy has obscured contemporary debate about urban citizenship. It identifies from the records of English towns a tradition of urban citizenship, which did not draw upon the intellectual legacy of classical models of the ‘citizen’. This was a vernacular citizenship, which was not peculiar to England, but which was present elsewhere in late medieval Europe. It was a citizenship that was defined and created through action. There were multiple, and divergent, ideas about citizenship, which encouraged townspeople to make demands, to assert rights, and to resist authority. This book exploits the rich archival sources of the five major towns in England—Bristol, Coventry, London, Norwich, and York—in order to present a new picture of town government and urban politics over three centuries. The power of urban governors was much more precarious than historians have imagined. Urban oligarchy could never prevail—whether ideologically or in practice—when there was never a single, fixed meaning of the citizen.

scholarly journals Future or Movement? The L2 Acquisition of Aller + V Forms

Languages ◽  
2021 ◽  
Vol 6 (1) ◽  
pp. 16
Author(s):  
Pascale Leclercq
Keyword(s):  
Native Speakers ◽  
Oral Narrative ◽  
L2 Acquisition ◽  
Cross Sectional ◽  
Developmental Patterns ◽  
Patterns Of Use ◽  
Modal Values ◽  
The Impact ◽  
Narrative Function ◽  
Semantic Values

This study aims to advance the understanding of the impact of the discursive context in the form-function mappings of aller + V forms by native speakers (NSs) and learners of French (NNSs), and to further knowledge about the developmental patterns of use of such forms at three proficiency levels (lower intermediate, upper intermediate, and advanced). While aller + V is often referred to as a periphrastic future form, i.e., a way to express temporal reference, it also takes a range of diverse semantic values (including spatial, aspectual, and modal values), and discursive functions. We therefore set out to examine data from a cross-sectional oral narrative and a longitudinal semi-guided interview task to find out to what extent aller + V forms are used by NSs and NNSs in a study abroad context. Our main results show that at lower intermediate level, spatial values dominate, while temporal and modal values emerge at upper intermediate and advanced levels. As regards the discursive functions of aller + V, learners make context appropriate choices (among others, narrative function in oral narratives, and stance-marking in interviews), but even at advanced level, their range of semantic values and discursive functions is more restricted than native speakers’.

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