Size, shape, and systematics of the Silurian trilobite Aulacopleura koninckii

2014 ◽  
Vol 88 (6) ◽  
pp. 1120-1138 ◽  
Author(s):  
Paul S. Hong ◽  
Nigel C. Hughes ◽  
H. David Sheets
Keyword(s):  
Relative Size ◽  
Trunk Region ◽  
Size And Shape ◽  
Systematic Description ◽  
Trunk Segment ◽  
Marked Variability ◽  
Character Variation ◽  
Complex Patterns ◽  
Shape And Size ◽  
Trunk Segments

A new dataset of the highest quality specimens of fully articulated, juvenile and mature exoskeletons of the Czech middle Silurian trilobite Aulacopleura koninckii offers improved resolution of original morphology by all measures considered. The degree of variation in both size and shape among later meraspid instars was constant, and suggesting targeted growth in both attributes. Size-related changes in the shape of the dorsal exoskeleton and of the segment-invariant cephalon were detected in the meraspid stage, but in the holaspid phase marked allometry was detected only in the trunk region, with the pygidium showing notable expansion in relative size. Meraspid cranidial allometry was subtle, with significant changes in instar form detectable only after several molts. This trilobite developed gradually throughout meraspid and holaspid ontogeny, with the synchronous cessation of trunk segment appearance and release at the onset of the holaspid phase. Precise development of shape and size occurs in the context of marked variability in the number of trunk segments at maturity, illustrating complex patterns of character variation within a species. A new systematic description establishes the synonymy of several subspecies with A. koninckii.

Ceramic Vessels, Site Permanence, and Group Size: A Mississippian Example

1984 ◽  
Vol 49 (4) ◽  
pp. 696-712 ◽  
Author(s):  
Gary Shapiro
Keyword(s):  
Group Size ◽  
Relative Size ◽  
Archaeological Sites ◽  
Vessel Size ◽  
Size And Shape ◽  
Ceramic Vessels ◽  
Georgia Piedmont ◽  
Site Variability

Data derived from analyses of vessel size and shape have been largely overlooked by researchers who seek to understand Mississippian site variability. Vessel form data are analyzed to demonstrate that relative site permanence and the relative size of group that lived at or visited sites are reflected in the size and shape of ceramic vessels. Vessel forms from four archaeological sites are compared, each of which played a different role within a single, late Mississippian society of the Georgia Piedmont.

Order Effects in Concomitant Attribute Judgments (Shape and Size)

1968 ◽  
Vol 27 (2) ◽  
pp. 360-362 ◽  
Author(s):  
Peter K. Leppmann ◽  
Roy B. Mefferd ◽  
Betty A. Wieland
Keyword(s):  
Necker Cube ◽  
Relative Size ◽  
Size Judgment ◽  
Order Effects ◽  
Stimulus Attribute ◽  
Shape And Size

This experiment was designed to determine whether judgment of one stimulus attribute would exert an influence on the judgment of a second attribute as a function of the relative phenomenal strength of the two attributes. One group of Ss was instructed to judge the apparent shape of a Necker cube and then to judge the apparent relative size of its two faces. Another group made the size-judgment first, then the shape-judgment. For most Ss, the two judgments were not independent and were influenced by which of the attributes was judged first.

Cooling Rates of Brake Drums and Discs

1965 ◽  
Vol 180 (1) ◽  
pp. 191-205 ◽  
Author(s):  
T.P. Newcomb ◽  
N. Millner
Keyword(s):  
Cooling Rate ◽  
Air Flow ◽  
Vehicle Speed ◽  
Uniform Temperature ◽  
Cooling Rates ◽  
Size And Shape ◽  
Slip Ring ◽  
Disc Brakes ◽  
Shape And Size ◽  
Time Plot

An investigation has been made of the rates of cooling of vehicle brake drums and discs. Thermocouples were inserted in the drums and discs and in the wheel hubs and their outputs fed via slip ring units to meters mounted inside the vehicle. The drums or discs were heated to a uniform temperature of 300°-400°C by drag braking and the rate at which they cooled measured while the vehicle was driven at constant speed. Measurements were made at various speeds in the range 0 to 90 mile/h. From the log (temperature) against time plot a cooling coefficient bv was determined. It is shown that at a vehicle speed v the quantity bv can be expressed in the form bv = b0 +Kv0·8 where b0 represents the loss of heat to the hub and K is a constant depending on the size and shape of the drum or disc. Values of these constants have been determined on a variety of cars having discs and drums varying from 7 in to 11 in diameter and on a lorry fitted with 16·75 in diameter drums. Cooling rates are shown to depend on shape and size of the disc or drum. Results show that the cooling rates of front brakes are about 20 per cent higher than the rear brakes and that front discs cool about 25 per cent more quickly than the corresponding drum size recommended for the same vehicle. The cooling rate of front discs did not change when wire wheels were fitted instead of solid wheels. Ventilated discs and solid discs were also compared. The effect of fitting dust shields on disc brakes is shown to reduce the cooling rates by about 30 per cent. The effect of otherwise disturbing the air flow was studied.

Synthesis and characterization of size- and shape-controlled silver nanoparticles

2018 ◽  
Vol 4 (1) ◽  
Author(s):  
Suparna Mukherji ◽  
Sharda Bharti ◽  
Gauri Shukla ◽  
Soumyo Mukherji
Keyword(s):  
Silver Nanoparticles ◽  
Nucleation And Growth ◽  
Detailed Review ◽  
Size And Shape ◽  
Physical Chemical ◽  
Application Potential ◽  
Shape Controlled ◽  
Synthesis Routes ◽  
Shape And Size

Abstract Silver nanoparticles (AgNPs) have application potential in diverse areas ranging from wound healing to catalysis and sensing. The possibility for optimizing the physical, chemical and optical properties for an application by tailoring the shape and size of silver nanoparticles has motived much research on methods for synthesis of size- and shape-controlled AgNPs. The shape and size of AgNPs are reported to vary depending on choice of the Ag precursor salt, reducing agent, stabilizing agent and on the synthesis technique used. This chapter provides a detailed review on various synthesis approaches that may be used for synthesis of AgNPs of desired size and shape. Silver nanoparticles may be synthesized using diverse routes, including, physical, chemical, photochemical, biological and microwave -based techniques. Synthesis of AgNPs of diverse shapes, such as, nanospheres, nanorods, nanobars, nanoprisms, decahedral nanoparticles and triangular bipyramids is also discussed for chemical-, photochemical- and microwave-based synthesis routes. The choice of chemicals used for reduction and stabilization of nanoparticles is found to influence their shape and size significantly. A discussion on the mechanism of synthesis of AgNPs through nucleation and growth processes is discussed for AgNPs of varying shape and sizes so as to provide an insight on the various synthesis routes. Techniques, such as, electron microscopy, spectroscopy, and crystallography that can be used for characterizing the AgNPs formed in terms of their shape, sizes, crystal structure and chemical composition are also discussed in this chapter. Graphical Abstract:

The Effect of Learned Perceptual Associations on Visuomotor Programming Varies with Kinematic Demands

2000 ◽  
Vol 12 (6) ◽  
pp. 950-964 ◽  
Author(s):  
Angela M. Haffenden ◽  
Melvyn A. Goodale
Keyword(s):  
Relative Size ◽  
Target Object ◽  
Perceptual Information ◽  
Visually Guided ◽  
Large Circle ◽  
Object Shape ◽  
Size Information ◽  
Demand Changes ◽  
Finger Posture ◽  
Shape And Size

The present set of experiments investigated the possibility that learned perceptual information can, under certain circumstances, be utilized by visuomotor programming. In Experiment 1 (N = 28), an association was established between the color and size of square wooden blocks (e.g., red = large; yellow = small, or vice-versa). In Experiment 2 (N = 28), an association was established between the shape and size of plastic objects (e.g., hexagon = large; circle = small, or vice-versa). It was expected that the learned associations would change the perceived size of two probe objects halfway in size between the large and small objects (the probe object matched by color or shape to the large group of objects would appear smaller than the probe object matched to the small group of objects as a result of within-group relative size comparisons). In both experiments, half of the participants grasped the target objects, and the other half estimated the size of the objects by opening their thumb and finger a matching amount. For Experiment 1, it was predicted that an influence of the lérned association on the treatment of the probe objects would be seen in manual estimations and in grip scaling because the kinematics of the grasping movement were very similar across trials. As predicted, the learned association between size and color was as easily incorporated into visually guided grasping as it was into visual perceptions. In Experiment 2, it was predicted that an influence of the learned perceptual association would be seen only in manual estimations, and not in grip scaling, because the variability in target object shape from trial to trial would demand changes in precontact finger posture across trials. Despite the significant effect of the size-shape association on size estimations, no influence was seen in preparatory grip scaling, probably because varying shape increased the metrical demands on visuomotor programming from those in Experiment 1. Together, the results suggest that visuomotor programming can make use of learned size information under some, but not all, conditions.

Acanthochondria helicoleni sp. nov. (Copepoda, Chondracanthidae) parasitic on Helicolenus lahillei (Scorpaeniformes, Sebastidae) from Argentinean waters

2010 ◽  
Vol 55 (4) ◽  
Author(s):  
Delfina Cantatore ◽  
Juan Timi
Keyword(s):  
New Species ◽  
Relative Size ◽  
Relative Length ◽  
Parasitic Copepod ◽  
The Body ◽  
Head Shape ◽  
A New Species ◽  
Shape And Size

AbstractA new species of a parasitic copepod, Acanthochondria helicoleni sp. nov. (Copepoda, Chondracanthidae), is described and illustrated from specimens collected within the branchial chambers of the rubio, Helicolenus lahillei Norman, 1937, from the Argentinean waters. The new species most closely resemble A. serrani Braicovich et Timi, 2009 collected in the same region, but differs in the general measurements and proportions of the body; primarily by the relative length of neck, shape of head, shape and size of genito-abdominal tagma and relative size of the trunk postero-lateral processes.

Brownian motions on shape and size-and-shape spaces

1994 ◽  
Vol 31 (1) ◽  
pp. 101-113 ◽  
Author(s):  
Huiling Le
Keyword(s):  
Dual Problem ◽  
Heat Kernels ◽  
Brownian Motions ◽  
Shape Spaces ◽  
Size And Shape ◽  
Shape And Size

The diffusions on the shape and size-and-shape spaces induced by brownian motions on the pre-size-and-shape spaces have been investigated in several papers (cf.). We here address the dual problem: the character of the diffusions on the pre-shape and pre-size-and-shape spaces which induce brownian motions on the shape and size-and-shape spaces. In particular we show that the shape and size-and-shape spaces for k labelled points in ℝm are stochastically complete if k > m and obtain the heat kernels of certain diffusions which induce brownian motions on the size-and-shape spaces.

scholarly journals Sexual size and shape dimorphism in Brachydesmus troglobius Daday, 1889 (Diplopoda, Polydesmida)

ZooKeys ◽  
2020 ◽  
Vol 930 ◽  
pp. 75-88
Author(s):  
Vukica Vujić ◽  
Luka Lučić ◽  
Sofija Pavković-Lučić ◽  
Bojan Ilić ◽  
Zvezdana Jovanović ◽  
...  
Keyword(s):  
Geometric Morphometrics ◽  
Morphological Trait ◽  
Trait Variation ◽  
Size Dimorphism ◽  
Size And Shape ◽  
Shape And Size

Until now, morphological trait variation has been investigated in several millipede species using geometric morphometrics. The present study is the first attempt to explore sexual shape and size dimorphism (SShD and SSD) of morphological structures in Polydesmida. We here analyse antennal, head, and leg SShD and SSD in Brachydesmus troglobius Daday, 1889. Our results show that SSD exists in all of the analysed structures, while SShD is present only in the legs. In comparison with females, males possess longer and wider legs, as well as longer antennae and a shorter head. Contrary to previous findings in some Julida, in B. troglobiusSSD of the antennae and legs varies more than SShD in these morphological structures.

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