scholarly journals Stable hooks: biomechanics of heteromorph ammonoids with U-shaped body chambers

2020 ◽  
Vol 86 (4) ◽  
pp. 267-279
Author(s):  
David J Peterman ◽  
Ryan Shell ◽  
Charles N Ciampaglio ◽  
Margaret M Yacobucci
Keyword(s):  
Intermediate Stage ◽  
Physical Models ◽  
Mature Stage ◽  
Hydrodynamic Drag ◽  
Centre Of Mass ◽  
Neutral Buoyancy ◽  
Selective Pressures ◽  
Adult Model ◽  
3D Printed ◽  
Neutrally Buoyant

ABSTRACT The biomechanics of uncoiled heteromorph ammonoids with body chambers that terminate in U-shaped hooks (ancylocones) were investigated with virtual and physical models of Audouliceras renauxianum. Virtual models were used to compute the hydrostatic properties of this morphotype. Audouliceras has the capacity for neutral buoyancy and this suggests that other taxa with similar proportions had this ability as well. Hydrostatic stability gradually increases during ontogeny, coincident with the larger degree of uncoiling. The juvenile planispiral stage has a similar stability and apertural orientation to the extant Nautilus. The adult stage, however, undergoes an increase in stability by a factor of over 3, while assuming an upward-facing posture. Counterintuitively, the stage during the formation of the shaft (before the growth of the U-shaped hook) is oriented horizontally. This intermediate stage would have had poor horizontal mobility due to the positioning of the hyponome below the centre of mass. The juvenile planispiral stage and mature stage, however, would have been well suited to horizontal backward movement with minimal rocking. Ancylocones are generally thought of as quasiplanktic vertical migrants. Thus, their relative horizontal swimming ability has been largely disregarded. Experiments on 3D printed, neutrally buoyant physical models reveal that hydrodynamic drag is indeed larger compared to Nautilus. However, Audouliceras could reach similar maximum horizontal velocities depending on the available thrust. Sepia-like thrusts yield velocities similar to equivalently sized Nautilus (c. 15 cm/s), while Nautilus-like thrusts yield velocities not much lower (c. 11 cm/s). Due to the hydrostatic properties of the ancylocone, the adult model undergoes less rocking (±4.5°) during movement than Nautilus (±10°). The minimal hydrodynamic consequences for ancylocones suggest that stability, orientation and directional efficiency are key selective pressures for some heteromorph shells, which may have primarily served as hydrostatic devices.

Development of Walking Pattern Evaluation System for Hypogravity Simulation

2008 ◽  
pp. 440-445
Author(s):  
R. Leães ◽  
R. Cambraia ◽  
F. Bacim ◽  
G. Dalmarco ◽  
A. Calder ◽  
...  
Keyword(s):  
Evaluation System ◽  
Water Immersion ◽  
Parabolic Flight ◽  
Time Constraints ◽  
Hydrodynamic Drag ◽  
Neutral Buoyancy ◽  
Freedom Of Movement ◽  
Partial Gravity ◽  
The Subject ◽  
Neutrally Buoyant

There are three primary techniques for simulating partial gravity: water immersion (neutral buoyancy), parabolic flight, and body suspension device (BSD) models. Underwater Immersion. During tests, a neutrally buoyant subject is ballasted to simulate the desired partial gravity loading. For example, one-sixth of the subject’s body mass is added in ballast if a lunar simulation is desired. Water immersion offers the subject freedom from time constraints and freedom of movement, but the hydrodynamic drag is disadvantageous for movement studies.

scholarly journals Estimation of sinking velocities using free-falling dynamically scaled models: foraminifera as a test case

2020 ◽  
Author(s):  
Matthew Walker ◽  
Stuart Humphries ◽  
Rudi Schuech
Keyword(s):  
Planktonic Foraminifera ◽  
Physical Models ◽  
Dynamic Scaling ◽  
Test Case ◽  
Dimensionless Numbers ◽  
Settling Particles ◽  
Extant Species ◽  
3D Printed ◽  
Sinking Velocities ◽  
Free Falling

AbstractThe velocity of settling particles is an important determinant of distribution in extinct and extant species with passive dispersal mechanisms, such as plants, corals, and phytoplankton. Here we adapt dynamic scaling, borrowed from engineering, to determine settling velocities. Dynamic scaling leverages physical models with relevant dimensionless numbers matched to achieve similar dynamics to the original object. Previous studies have used flumes, wind tunnels, or towed models to examine fluid flows around objects with known velocities. Our novel application uses free-falling models to determine the unknown sinking velocities of planktonic foraminifera – organisms important to our understanding of the Earth’s current and historic climate. Using enlarged 3D printed models of microscopic foraminifera tests, sunk in viscous mineral oil to match their Reynolds numbers and drag coefficients, we predict sinking velocities of real tests in seawater. This method can be applied to study other settling particles such as plankton, spores, or seeds.Summary StatementWe developed a novel method to determine the sinking velocities of biologically important microscale particles using 3D printed scale models.

On the use of ammonium for buoyancy in squids

1979 ◽  
Vol 59 (2) ◽  
pp. 259-276 ◽  
Author(s):  
M. R. Clarke ◽  
E. J. Denton ◽  
J. B. Gilpin-Brown
Keyword(s):  
Developmental Stage ◽  
Sea Water ◽  
The Body ◽  
The Other ◽  
Neutral Buoyancy ◽  
Rich Solution ◽  
Almost All ◽  
Neutrally Buoyant

Squids (teuthoids) fall into two distinct groups according to their density in sea water. Squids of one group are considerably denser than sea water and must swim to stop sinking; squids in the other group are nearly neutrally buoyant. Analyses show that in almost all the neutrally buoyant squids large amounts of ammonium are present. This ammonium is not uniformly distributed throughout the body but is mostly confined to special tissues where its concentration can approach half molar. The locations of such tissues differ according to the species and developmental stage of the squid. It is clear that the ammonium-rich solution are almost isosmotic with sea water but of lower density and they are present in sufficient volume to provide the main buoyancy mechanism of these squids. A variety of evidence is given which suggests that squids in no less than 12 of the 26 families achieve near-neutral buoyancy in this way and that 14 families contain squids appreciably denser than sea water [at least one family contains both types of squid]. Some of the ammonium-rich squids are extremely abundant in the oceans.

3D Printing of Medical Models: A Literature Review

2017 ◽  
Author(s):  
Xingjian Wei ◽  
Li Zeng ◽  
Zhijian Pei
Keyword(s):  
3D Printing ◽  
Literature Review ◽  
Medical Curriculum ◽  
Industrial Applications ◽  
Physical Models ◽  
Research Directions ◽  
Anatomical Structures ◽  
Medical Models ◽  
3D Printed ◽  
Anatomy Teaching

Medical models are physical models of human or animal anatomical structures such as skull and heart. Such models are used in simulation and planning of complex surgeries. They can also be utilized for anatomy teaching in medical curriculum. Traditionally, medical models are fabricated by paraffin wax or silicone casting. However, this method is time-consuming, of low quality, and not suitable for personalization. Recently, 3D printing technologies are used to fabricate medical models. Various applications of 3D printed medical models in surgeries and anatomy teaching have been reported, and their advantages over traditional medical models have been well-documented. However, 3D printing of medical models bears some special challenges compared to industrial applications of 3D printing. This paper reviews more than 50 publications on 3D printing of medical models between 2006 and 2016, and discusses knowledge gaps and potential research directions in this field.

Using 3D printed physical models to monitor knowledge integration in biochemistry

2018 ◽  
Vol 19 (4) ◽  
pp. 1199-1215 ◽  
Author(s):  
Melissa A. Babilonia-Rosa ◽  
H. Kenny Kuo ◽  
Maria T. Oliver-Hoyo
Keyword(s):  
Small Molecules ◽  
Knowledge Integration ◽  
Noncovalent Interactions ◽  
Three Dimensional ◽  
Student Understanding ◽  
Physical Models ◽  
Dimensional Structure ◽  
Instructional Resources ◽  
3D Printed ◽  
Different Sources

Noncovalent interactions determine the three-dimensional structure of macromolecules and the binding interactions between molecules. Students struggle to understand noncovalent interactions and how they relate to structure–function relationships. Additionally, students’ difficulties translating from two-dimensional representations to three-dimensional representations add another layer of complexity found in macromolecules. Therefore, we developed instructional resources that use 3D physical models to target student understanding of noncovalent interactions of small molecules and macromolecules. To this effect, we monitored indicators of knowledge integration as evidenced in student-generated drawings. Analysis of the drawings revealed that students were able to incorporate relevant conceptual features into their drawings from different sources as well as present their understanding from different perspectives.

In situ acoustic estimates of the swimbladder volume of Atlantic herring (Clupea harengus)

2004 ◽  
Vol 61 (3) ◽  
pp. 323-337 ◽  
Author(s):  
Redwood W. Nero ◽  
Charles H. Thompson ◽  
J. Michael Jech
Keyword(s):  
Gulf Of Maine ◽  
Clupea Harengus ◽  
Sea Surface ◽  
Atlantic Herring ◽  
Acoustic Measurements ◽  
Neutral Buoyancy ◽  
Fish Weight ◽  
Neutrally Buoyant ◽  
Boyle’S Law

Abstract Acoustic measurements at 1.5–5 kHz on fish in the Gulf of Maine showed a swimbladder-resonance peak near 2.5 kHz at 160–190-m depth. Midwater trawls confirmed that the fish were likely to be Atlantic herring (Clupea harengus) of 19–29 cm length. Calculation using a model of swimbladder resonance gives swimbladder volumes of 1.2% of fish weight at 160–190 m. Extrapolation of this volume of gas using Boyle's Law suggests that at the sea surface, these herring would need to inflate their swimbladders by up to five to six times the volume required for neutral buoyancy. If these fish were to maintain this volume of gas with surface “gulping”, they would need to submerge from the sea surface with a 30% excess buoyancy. In general, swimbladders of the Clupeidae may have greater volumes of gas than if the fish were neutrally buoyant at the sea surface and the interpretation of HF-echosounder surveys may be additionally complex when the volume of gas and swimbladder volume are difficult to predict. Mechanisms of how herring obtain additional swimbladder gas are discussed.

scholarly journals The Clinical Application of 3D-Printed Boluses in Superficial Tumor Radiotherapy

2021 ◽  
Vol 11 ◽  
Author(s):  
Xiran Wang ◽  
Xuetao Wang ◽  
Zhongzheng Xiang ◽  
Yuanyuan Zeng ◽  
Fang Liu ◽  
...  
Keyword(s):  
3D Printing ◽  
Radiation Dose ◽  
Material Selection ◽  
Skin Surface ◽  
High Energy ◽  
Clinical Applications ◽  
Physical Models ◽  
Target Area ◽  
Air Gaps ◽  
3D Printed

During the procedure of radiotherapy for superficial tumors, the key to treatment is to ensure that the skin surface receives an adequate radiation dose. However, due to the presence of the built-up effect of high-energy rays, equivalent tissue compensators (boluses) with appropriate thickness should be placed on the skin surface to increase the target radiation dose. Traditional boluses do not usually fit the skin perfectly. Wet gauze is variable in thickness day to day which results in air gaps between the skin and the bolus. These unwanted but avoidable air gaps lead to a decrease of the radiation dose in the target area and can have a poor effect on the outcome. Three-dimensional (3D) printing, a new rising technology named “additive manufacturing” (AM), could create physical models with specific shapes from digital information by using special materials. It has been favored in many fields because of its advantages, including less waste, low-cost, and individualized design. It is not an exception in the field of radiotherapy, personalized boluses made through 3D printing technology also make up for a number of shortcomings of the traditional commercial bolus. Therefore, an increasing number of researchers have tried to use 3D-printed boluses for clinical applications rather than commercial boluses. Here, we review the 3D-printed bolus’s material selection and production process, its clinical applications, and potential radioactive dermatitis. Finally, we discuss some of the challenges that still need to be addressed with the 3D-printed boluses.

scholarly journals The Effect of Discharge Depth on Contaminant Dispersion in Turbulent Open Channel Flow

1982 ◽  
Vol 35 (2) ◽  
pp. 107 ◽  
Author(s):  
Albert J Gabric
Keyword(s):  
Total Mass ◽  
Open Channel ◽  
Open Channel Flow ◽  
Finite Depth ◽  
Centre Of Mass ◽  
Contaminant Dispersion ◽  
Transport And Diffusion ◽  
Neutrally Buoyant ◽  
Analytical Expressions ◽  
And Diffusion

The transport and diffusion of neutrally buoyant, conservative contaminants in an open, finite depth channel is analysed at times before uniform mixing over the depth has occurred. Analytical expressions for the total mass at a given depth, the centre of mass and the variance of the contaminant patch are presented.

scholarly journals Physical Visualization of Geospatial Datasets

2022 ◽  
Author(s):  
Hessam Djavaherpour ◽  
Ali Mahdavi-Amiri ◽  
Faramarz Samavati
Keyword(s):  
Digital Fabrication ◽  
Physical Models ◽  
Grid System ◽  
Computer Screen ◽  
The Earth ◽  
3D Printed ◽  
Geospatial Datasets ◽  
2D And 3D ◽  
Global Grid

Geospatial datasets are too complex to easily visualize and understand on a computer screen. Combining digital fabrication with a discrete global grid system (DGGS) can produce physical models of the Earth for visualizing multiresolution geospatial datasets. This proposed approach includes a mechanism for attaching a set of 3D printed segments to produce a scalable model of the Earth. The authors have produced two models that support the attachment of different datasets both in 2D and 3D format.

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