scholarly journals How birds direct impulse to minimize the energetic cost of foraging flight

2017 ◽  
Vol 3 (5) ◽  
pp. e1603041 ◽  
Author(s):  
Diana D. Chin ◽  
David Lentink
Keyword(s):  
Energetic Cost ◽  
Foraging Flight

Quasi-Barrierless Submolecular Motion in Mechanically Interlocked Carbon Nanotubes

2020 ◽  
Author(s):  
Julia Villalva ◽  
Belén Nieto-Ortega ◽  
Manuel Melle-Franco ◽  
Emilio Pérez
Keyword(s):  
Density Functional ◽  
Close Contact ◽  
Tight Binding ◽  
Energetic Cost ◽  
Molecular Fragments ◽  
Activation Barriers ◽  
Flat Surfaces ◽  
Different Types ◽  
Atomically Flat ◽  
Derivatives Of

The motion of molecular fragments in close contact with atomically flat surfaces is still not fully understood. Does a more favourable interaction imply a larger barrier towards motion even if there are no obvious minima? Here, we use mechanically interlocked rotaxane-type derivatives of SWNTs (MINTs) featuring four different types of macrocycles with significantly different affinities for the SWNT thread as models to study this problem. Using molecular dynamics, we find that there is no direct correlation between the interaction energy of the macrocycle with the SWNT and its ability to move along or around it. Density functional tight-binding calculations reveal small (<2.5 Kcal·mol-1) activation barriers, the height of which correlates with the commensurability of the aromatic moieties in the macrocycle with the SWNT. Our results show that macrocycles in MINTs rotate and translate freely around and along SWNTs at room temperature, with an energetic cost lower than the rotation around the C−C bond in ethane.<br>

SAMPL6 Octanol-Water Partition Coefficients from Alchemical Free Energy Calculations with MBIS Atomic Charges

2019 ◽  
Author(s):  
Maximiliano Riquelme ◽  
Esteban Vöhringer-Martinez
Keyword(s):  
Free Energy ◽  
Electron Density ◽  
Free Energy Calculations ◽  
Basis Set ◽  
Energetic Cost ◽  
Atomic Charges ◽  
Free Energies ◽  
Energy Calculations ◽  
Alchemical Free Energy ◽  
Alchemical Free Energy Calculations

In molecular modeling the description of the interactions between molecules forms the basis for a correct prediction of macroscopic observables. Here, we derive atomic charges from the implicitly polarized electron density of eleven molecules in the SAMPL6 challenge using the Hirshfeld-I and Minimal Basis Set Iterative Stockholder(MBIS) partitioning method. These atomic charges combined with other parameters in the GAFF force field and different water/octanol models were then used in alchemical free energy calculations to obtain hydration and solvation free energies, which after correction for the polarization cost, result in the blind prediction of the partition coefficient. From the tested partitioning methods and water models the S-MBIS atomic charges with the TIP3P water model presented the smallest deviation from the experiment. Conformational dependence of the free energies and the energetic cost associated with the polarization of the electron density are discussed.

scholarly journals Prey Size Decline as a Unifying Ecological Selecting Agent in Pleistocene Human Evolution

Quaternary ◽  
2021 ◽  
Vol 4 (1) ◽  
pp. 7
Author(s):  
Miki Ben-Dor ◽  
Ran Barkai
Keyword(s):  
Prey Size ◽  
Prey Availability ◽  
Stone Tool ◽  
Foraging Efficiency ◽  
Energetic Cost ◽  
Large Prey ◽  
Biomass Density ◽  
Cultural Changes ◽  
Progressive Decline ◽  
Brain Expansion

We hypothesize that megafauna extinctions throughout the Pleistocene, that led to a progressive decline in large prey availability, were a primary selecting agent in key evolutionary and cultural changes in human prehistory. The Pleistocene human past is characterized by a series of transformations that include the evolution of new physiological traits and the adoption, assimilation, and replacement of cultural and behavioral patterns. Some changes, such as brain expansion, use of fire, developments in stone-tool technologies, or the scale of resource intensification, were uncharacteristically progressive. We previously hypothesized that humans specialized in acquiring large prey because of their higher foraging efficiency, high biomass density, higher fat content, and the use of less complex tools for their acquisition. Here, we argue that the need to mitigate the additional energetic cost of acquiring progressively smaller prey may have been an ecological selecting agent in fundamental adaptive modes demonstrated in the Paleolithic archaeological record. We describe several potential associations between prey size decline and specific evolutionary and cultural changes that might have been driven by the need to adapt to increased energetic demands while hunting and processing smaller and smaller game.

scholarly journals Quantifying the energetic cost of food quality constraints on resting metabolism to integrate nutritional and metabolic ecology

2021 ◽  
Author(s):  
Thomas Ruiz ◽  
Apostolos‐Manuel Koussoroplis ◽  
Michael Danger ◽  
Jean‐Pierre Aguer ◽  
Nicole Morel‐Desrosiers ◽  
...  
Keyword(s):  
Food Quality ◽  
Energetic Cost ◽  
Metabolic Ecology ◽  
Resting Metabolism

scholarly journals Single bacterial resolvases first exploit, then constrain intrinsic dynamics of the Holliday junction to direct recombination

2021 ◽  
Author(s):  
Sujay Ray ◽  
Nibedita Pal ◽  
Nils G Walter
Keyword(s):  
Cluster Analysis ◽  
Homologous Recombination ◽  
Single Molecule ◽  
Holliday Junction ◽  
Energetic Cost ◽  
Genomic Integrity ◽  
Dna Molecules ◽  
Single Molecule Fluorescence ◽  
And Cluster Analysis ◽  
Fluorescence Observation

Abstract Homologous recombination forms and resolves an entangled DNA Holliday Junction (HJ) crucial for achieving genetic reshuffling and genome repair. To maintain genomic integrity, specialized resolvase enzymes cleave the entangled DNA into two discrete DNA molecules. However, it is unclear how two similar stacking isomers are distinguished, and how a cognate sequence is found and recognized to achieve accurate recombination. We here use single-molecule fluorescence observation and cluster analysis to examine how prototypic bacterial resolvase RuvC singles out two of the four HJ strands and achieves sequence-specific cleavage. We find that RuvC first exploits, then constrains the dynamics of intrinsic HJ isomer exchange at a sampled branch position to direct cleavage toward the catalytically competent HJ conformation and sequence, thus controlling recombination output at minimal energetic cost. Our model of rapid DNA scanning followed by ‘snap-locking’ of a cognate sequence is strikingly consistent with the conformational proofreading of other DNA-modifying enzymes.

scholarly journals Amelioration of the Cost of Conjugative Plasmid Carriage in Eschericha coli K12

Genetics ◽  
2003 ◽  
Vol 165 (4) ◽  
pp. 1641-1649
Author(s):  
Cecilia Dahlberg ◽  
Lin Chao
Keyword(s):  
Drug Resistance ◽  
Multiple Drug Resistance ◽  
Conjugative Plasmid ◽  
Energetic Cost ◽  
Multiple Drug ◽  
Genetic Changes ◽  
Batch Cultures ◽  
Transfer Rates ◽  
Bacterial Plasmid ◽  
The Cost

Abstract Although plasmids can provide beneficial functions to their host bacteria, they might confer a physiological or energetic cost. This study examines how natural selection may reduce the cost of carrying conjugative plasmids with drug-resistance markers in the absence of antibiotic selection. We studied two plasmids, R1 and RP4, both of which carry multiple drug resistance genes and were shown to impose an initial fitness cost on Escherichia coli. To determine if and how the cost could be reduced, we subjected plasmid-containing bacteria to 1100 generations of evolution in batch cultures. Analysis of the evolved populations revealed that plasmid loss never occurred, but that the cost was reduced through genetic changes in both the plasmids and the bacteria. Changes in the plasmids were inferred by the demonstration that evolved plasmids no longer imposed a cost on their hosts when transferred to a plasmid-free clone of the ancestral E. coli. Changes in the bacteria were shown by the lowered cost when the ancestral plasmids were introduced into evolved bacteria that had been cured of their (evolved) plasmids. Additionally, changes in the bacteria were inferred because conjugative transfer rates of evolved R1 plasmids were lower in the evolved host than in the ancestral host. Our results suggest that once a conjugative bacterial plasmid has invaded a bacterial population it will remain even if the original selection is discontinued.

Energetic cost of girdling in a notodontid caterpillar, Oedemasia leptinoides

2021 ◽  
Vol 15 (2) ◽  
pp. 161-170
Author(s):  
Brianna K. Trejo ◽  
Matthew E. Gifford ◽  
David E. Dussourd
Keyword(s):  
Energetic Cost

scholarly journals Increased aortic compliance decreases the energetic cost of left ventricular ejection

2000 ◽  
Vol 2 ◽  
pp. 120-121
Author(s):  
P. Kolh ◽  
V. D'Orio ◽  
B. Lambermont ◽  
P. Gerard ◽  
C. Gommes ◽  
...  
Keyword(s):  
Left Ventricular ◽  
Ventricular Ejection ◽  
Left Ventricular Ejection ◽  
Energetic Cost ◽  
Aortic Compliance

The influence of roost closure on the roosting and foraging behaviour of Eptesicus fuscus (Chiroptera: Vespertilionidae)

1986 ◽  
Vol 64 (5) ◽  
pp. 1128-1133 ◽  
Author(s):  
R. Mark Brigham ◽  
M. Brock Fenton
Keyword(s):  
Reproductive Success ◽  
Direct Observation ◽  
Foraging Behaviour ◽  
Eptesicus Fuscus ◽  
Maximum Distance ◽  
Radio Tracking ◽  
Site Specific ◽  
Big Brown Bats ◽  
Specific Factors ◽  
Foraging Flight

We used radio tracking and direct observation to determine the effect of roost closure on the roosting and foraging behaviour of big brown bats (Eptesicus fuscus) in maternity colonies near Ottawa. Individuals were site loyal, but after eviction they moved short distances to new roosts where they tended to produce fewer offspring. The time spent on the first foraging flight, the maximum distance travelled, and the use of feeding areas did not change with exclusion. The results suggest that bats roost to take advantage of site-specific factors that may increase reproductive success.

scholarly journals Limitations imposed by wearing armour on Medieval soldiers' locomotor performance

2011 ◽  
Vol 279 (1729) ◽  
pp. 640-644 ◽  
Author(s):  
Graham N. Askew ◽  
Federico Formenti ◽  
Alberto E. Minetti
Keyword(s):  
Fifteenth Century ◽  
Physical Performance ◽  
Energy Use ◽  
Steel Plate ◽  
Energetic Cost ◽  
Entire Body ◽  
Additional Mass ◽  
Medieval Europe ◽  
Cost Of Locomotion ◽  
Locomotor Energetics

In Medieval Europe, soldiers wore steel plate armour for protection during warfare. Armour design reflected a trade-off between protection and mobility it offered the wearer. By the fifteenth century, a typical suit of field armour weighed between 30 and 50 kg and was distributed over the entire body. How much wearing armour affected Medieval soldiers' locomotor energetics and biomechanics is unknown. We investigated the mechanics and the energetic cost of locomotion in armour, and determined the effects on physical performance. We found that the net cost of locomotion ( C met ) during armoured walking and running is much more energetically expensive than unloaded locomotion. C met for locomotion in armour was 2.1–2.3 times higher for walking, and 1.9 times higher for running when compared with C met for unloaded locomotion at the same speed. An important component of the increased energy use results from the extra force that must be generated to support the additional mass. However, the energetic cost of locomotion in armour was also much higher than equivalent trunk loading. This additional cost is mostly explained by the increased energy required to swing the limbs and impaired breathing. Our findings can predict age-associated decline in Medieval soldiers' physical performance, and have potential implications in understanding the outcomes of past European military battles.

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