scholarly journals Intraspecific variation in testis asymmetry in birds: evidence for naturally occurring compensation

2009 ◽  
Vol 276 (1665) ◽  
pp. 2279-2284 ◽  
Author(s):  
Sara Calhim ◽  
Tim R. Birkhead
Keyword(s):  
Intraspecific Variation ◽  
Reproductive Investment ◽  
Quantitative Approach ◽  
The Other ◽  
Internal Organs ◽  
Trade Off ◽  
Naturally Occurring ◽  
Left And Right ◽  
Compensation Hypothesis

In many taxa, the left and right testes often differ in size. The compensation hypothesis states that one testis of the pair serves as a ‘back-up’ for any reduced function in the other and provides a mechanism to explain intraspecific variation in degree and direction of gonad asymmetry. Although testis asymmetry is common in birds, evidence for natural testis compensation is unknown. Using a novel quantitative approach that can be applied to any bilateral organ or structure, we show that testis compensation occurs naturally in birds and can be complete when one testis fails to develop. Owing to a recurrent risk of testis impairment and an evolutionary trade-off between natural and sexual selections acting on the arrangement of internal organs in species with abdominal and/or seasonal testes, compensation adds an important, but neglected, dimension to measures of male reproductive investment.

Evidence for neither the compensation hypothesis nor the expensive-tissue hypothesis in Carassius auratus

2014 ◽  
Vol 64 (2) ◽  
pp. 177-187 ◽  
Author(s):  
Jiao Liu ◽  
Cai Quan Zhou ◽  
Wen Bo Liao
Keyword(s):  
Carassius Auratus ◽  
The Other ◽  
Testis Size ◽  
Left Testis ◽  
Brain Mass ◽  
Gonad Mass ◽  
Left And Right ◽  
Compensation Hypothesis ◽  
Gut Length ◽  
Expensive Tissue Hypothesis

In many taxa, the left and right testes often differ in size. The compensation hypothesis states that an increase in size of one testis can compensate for a reduced function in the other testis. Moreover, the expensive-tissue hypothesis predicts that an increase in investment of a metabolically costly tissue is offset by decreasing investment in the other metabolically costly tissues. Here we tested these two hypotheses in Carassius auratus, by analysing difference between left and right testes mass, and between brain mass and both gut length and gonad mass (testes mass in males and clutch mass in females). We found no difference between left and right testis mass and no correlations between relative testis size and body measurements. These findings suggest that the left testis cannot serve a compensatory role. Nonetheless, contrary to the predictions of the expensive-tissue hypothesis, brain mass was positively correlated with both gut length and gonad mass within each sex. This positive correlation between brain mass and other organs (gut, gonad and clutch tissues) suggests that organisms may compensate for substantial variation in investment in tissues without sacrificing other expensive tissues.

scholarly journals Black Hole Algorithm for Sustainable Design of Counterfort Retaining Walls

2020 ◽  
Vol 12 (7) ◽  
pp. 2767 ◽  
Author(s):  
Víctor Yepes ◽  
José V. Martí ◽  
José García
Keyword(s):  
Black Hole ◽  
Sustainable Design ◽  
Retaining Walls ◽  
The Other ◽  
Trade Off ◽  
Construction Company ◽  
Geometric Variables ◽  
The Stability ◽  
The Cost ◽  
Black Hole Algorithm

The optimization of the cost and CO 2 emissions in earth-retaining walls is of relevance, since these structures are often used in civil engineering. The optimization of costs is essential for the competitiveness of the construction company, and the optimization of emissions is relevant in the environmental impact of construction. To address the optimization, black hole metaheuristics were used, along with a discretization mechanism based on min–max normalization. The stability of the algorithm was evaluated with respect to the solutions obtained; the steel and concrete values obtained in both optimizations were analyzed. Additionally, the geometric variables of the structure were compared. Finally, the results obtained were compared with another algorithm that solved the problem. The results show that there is a trade-off between the use of steel and concrete. The solutions that minimize CO 2 emissions prefer the use of concrete instead of those that optimize the cost. On the other hand, when comparing the geometric variables, it is seen that most remain similar in both optimizations except for the distance between buttresses. When comparing with another algorithm, the results show a good performance in optimization using the black hole algorithm.

scholarly journals Glucocorticoids, state-dependent reproductive investment and success in the face of danger in a long-lived bird

2020 ◽  
Author(s):  
Kristina Noreikienė ◽  
Kim Jaatinen ◽  
Benjamin B. Steele ◽  
Markus Öst
Keyword(s):  
Predation Risk ◽  
Telomere Length ◽  
Clutch Size ◽  
Body Condition ◽  
Nest Predation ◽  
Hatching Success ◽  
Reproductive Investment ◽  
Trade Off ◽  
Relative Telomere Length ◽  
Future Reproduction

AbstractGlucocorticoid hormones may mediate trade-offs between current and future reproduction. However, understanding their role is complicated by predation risk, which simultaneously affects the value of the current reproductive investment and elevates glucocorticoid levels. Here, we shed light on these issues in long-lived female Eiders (Somateria mollissima) by investigating how current reproductive investment (clutch size) and hatching success relate to faecal glucocorticoid metabolite [fGCM] level and residual reproductive value (minimum years of breeding experience, body condition, relative telomere length) under spatially variable predation risk. Our results showed a positive relationship between colony-specific predation risk and mean colony-specific fGCM levels. Clutch size and female fGCM were negatively correlated only under high nest predation and in females in good body condition, previously shown to have a longer life expectancy. We also found that younger females with longer telomeres had smaller clutches. The drop in hatching success with increasing fGCM levels was least pronounced under high nest predation risk, suggesting that elevated fGCM levels may allow females to ensure some reproductive success under such conditions. Hatching success was positively associated with female body condition, with relative telomere length, particularly in younger females, and with female minimum age, particularly under low predation risk, showing the utility of these metrics as indicators of individual quality. In line with a trade-off between current and future reproduction, our results show that high potential for future breeding prospects and increased predation risk shift the balance toward investment in future reproduction, with glucocorticoids playing a role in the resolution of this trade-off.

Effect of Induced Incomplete Ossification of the Humeral Condyle on Ex Vivo Humeral Condylar Biomechanics

2020 ◽  
Author(s):  
Logan M. Scheuermann ◽  
Michael G. Conzemius
Keyword(s):  
Mechanical Testing ◽  
Study Design ◽  
Ex Vivo ◽  
Peak Load ◽  
Testing System ◽  
Condylar Fracture ◽  
Naturally Occurring ◽  
Left And Right ◽  
Condylar Fractures ◽  
Humeral Condyle

Abstract Objective The aim of this study was to investigate the effects of an induced incomplete ossification of the humeral condyle (IOHC) lesion on ex vivo canine humeral condylar biomechanics. Study Design Nine paired cadaveric elbows were collected from mature dogs weighing between 20 and 25 kg. Left and right limbs were randomized to IOHC or normal groups. Limbs were prepared for mechanical testing; ligaments were preserved and an IOHC lesion was created. Elbows were potted, positioned into a biomaterials testing system at an angle of 135 degrees and axially loaded to failure at a rate of 30 mm/minute. Results Induced IOHC lesions reduced peak load (p = 0.02) when compared with an intact humerus. There was no difference between stiffness (p = 0.36) of intact humeri or humeri with an induced IOHC lesion. An induced IOHC lesion increased (p = 0.012) the probability of intracondylar fracture under load. Conclusion Cadaveric humeri are weakened by the creation of an intracondylar osteotomy and fractures secondary to induced IOHC are similar to spontaneous humeral condylar fractures. These findings support the hypothesis that naturally occurring IOHC weakens the humeral condyle and may predispose to humeral condylar fracture.

Identifying opportunities for value chain development in the Kenyan coffee sector

2018 ◽  
Vol 47 (2) ◽  
pp. 150-159 ◽  
Author(s):  
Emerta Aragie
Keyword(s):  
Value Chain ◽  
Export Performance ◽  
Export Subsidy ◽  
The Other ◽  
Cash Crop ◽  
Trade Off ◽  
Cash Crops ◽  
Standard Value ◽  
Coffee Sector ◽  
Productivity Gains

By developing a model that describes the Kenyan coffee value chain, this study evaluates opportunities emanating from four scenarios representing productivity gains in the various value chain stages of the coffee sector and additional three scenarios reflecting shifts in market situations. Results show that productivity-enhancing policies have stronger effects on coffee output and export performance if they target the milling stage of the value chain. Export subsidy and favourable external marketing conditions also have stronger effects, distributed comparably across the various value chain stages. We, however, found that these gains in the coffee sector come at the expense of other cash crops such as cotton, tea, sugar and tobacco. The approach followed in this study is relevant as this trade-off between coffee and the other cash crop sectors may not be visibly shown using standard value chain approaches.

Practical Aspects of Propulsion Shaft Alignment

2021 ◽  
Author(s):  
Kyriakos Avgouleas ◽  
Emmanouil Sarris ◽  
George Gougoulidis
Keyword(s):  
Cost Effectiveness ◽  
Numerical Model ◽  
High Speed ◽  
The Other ◽  
Technical Literature ◽  
Trade Off ◽  
Fea Model ◽  
Shaft Alignment ◽  
Alignment Strategy ◽  
Potential Damage

The economical and operational implications of poor alignment are indisputable for the propulsion shafting system of a commercial vessel. This holds true for naval vessels as well, although far less documented in the technical literature. This paper addresses some of the challenges associated with the proper alignment of a high-speed naval craft, which has been in service for many years. Laser bore-sighting was performed on a Guided Missile Fast Patrol Boat resting on a docking cradle. The measured bearing offsets were input to a FEA model of the shafting system to calculate bearing reactions and detect potential misalignment issues. Subsequent decisions regarding corrective measures take into account the results computed by the numerical model, experience from sister ships, the available documentation from the building yard and several other factors which are discussed in the paper. The solutions proposed are targeted towards a balanced trade-off between cost effectiveness and out-of-service time on one hand, and the risk of potential damage from misalignment on the other hand, which would seriously disrupt the ship’s operational availability. Practical aspects and lessons identified in the process are also presented, which demonstrate the distinct differences in alignment strategy of a high-speed naval craft compared to a typical commercial vessel.

Interactions between DNA-bound trimers of the yeast heat shock factor

1994 ◽  
Vol 14 (1) ◽  
pp. 501-508
Author(s):  
J J Bonner ◽  
C Ballou ◽  
D L Fackenthal
Keyword(s):  
Heat Shock ◽  
Protein Complexes ◽  
Consensus Sequence ◽  
The Other ◽  
Inverted Repeats ◽  
Electrophoretic Mobilities ◽  
Naturally Occurring ◽  
Initial Identification ◽  
Dyad Symmetry ◽  
Chemical Cross Linking

The heat shock transcription factor (HSF) is a trimer that binds to DNA containing inverted repeats of the sequence nGAAn. HSF can bind DNA with the sequence nGAAnnTTCn or with the sequence nTTCnnGAAn, with little preference for either sequence over the other. However, (nGAAnnTTCn)2 is considerably less active as a heat shock response element (HSE) than is (nTTCnnGAAn)2. The electrophoretic mobilities of DNA-protein complexes and chemical cross-linking between protein monomers indicate that the sequence (nGAAnnTTCn)2 is capable of binding a single HSF trimer. In contrast, the sequence with higher biological activity, (nTTCnnGAAn)2, is capable of binding two trimers. Thus, the ability of four-nGAAn-element HSEs to bind one or two trimers depends on the permutation with which the elements are presented. A survey of naturally occurring HSEs shows the sequence (nTTCnnGAAn)2 to be the more prevalent. We suggest that the greater ability of one permutation over the other to bind two HSF trimers accounts for the initial identification of the naturally occurring heat shock consensus sequence as a region of dyad symmetry.

Rediagnosis of the squat lobster genus Gastroptychus Caullery, 1896, with a new genus Sternostylus and a new family Sternostylidae (Crustacea: Decapoda: Anomura: Chirostyloidea)

Zootaxa ◽  
2018 ◽  
Vol 4524 (1) ◽  
pp. 77 ◽  
Author(s):  
KEIJI BABA ◽  
SHANE T. AHYONG ◽  
KAREEN E. SCHNABEL
Keyword(s):  
Type Species ◽  
Anterior Margin ◽  
New Genus ◽  
Sister Group ◽  
Sensu Stricto ◽  
The Other ◽  
Squat Lobster ◽  
Terminal Spine ◽  
New Family ◽  
Left And Right

The chirostyloidean squat lobster genus Gastroptychus Caullery, 1896 is revised and is split into two genera: Gastroptychus sensu stricto (type species, Ptychogaster spinifer A. Milne-Edwards, 1880) and Sternostylus new genus (type species, Ptychogaster formosus Filhol, 1884). Gastroptychus sensu stricto, is restricted to nine species with a sternal plastron, at sternite 3, abruptly demarcated from the preceding sternites (excavated sternum) by a distinct step forming a well-defined transverse or concave anterior margin at the articulation with maxillipeds 3, the maxillipeds 3 widely separated, with the distal parts accommodated in the excavated sternum between the left and right maxillipeds 3 when folded, and the P2–4 dactyli with the terminal spine demarcated by a suture. Sternostylus new genus, represented by 12 species, has the sternite 3 anteriorly bluntly produced medially and steeply sloping anterodorsally to the anterior sternite, with a pair of spines directly behind the anterior margin, the left and right maxillipeds 3 adjacent, and the P2–4 dactyli ending in an indistinctly demarcated corneous spine. The above-mentioned characters of Gastroptychus are consistent with Chirostylidae sensu stricto. Published molecular phylogenies indicate, however, that Sternostylus is the sister group to all the other Chirostylidae, and is designated the type genus of a new family, Sternostylidae. 

COMPUTING THE RUPTURE DEGREE IN COMPOSITE GRAPHS

2010 ◽  
Vol 21 (03) ◽  
pp. 311-319 ◽  
Author(s):  
AYSUN AYTAC ◽  
ZEYNEP NIHAN ODABAS
Keyword(s):  
Complete Graph ◽  
Connected Graph ◽  
The Other ◽  
Trade Off ◽  
Number Of Components ◽  
Np Complete ◽  
Work Done ◽  
Better Than

The rupture degree of an incomplete connected graph G is defined by [Formula: see text] where w(G - S) is the number of components of G - S and m(G - S) is the order of a largest component of G - S. For the complete graph Kn, rupture degree is defined as 1 - n. This parameter can be used to measure the vulnerability of a graph. Rupture degree can reflect the vulnerability of graphs better than or independent of the other parameters. To some extent, it represents a trade-off between the amount of work done to damage the network and how badly the network is damaged. Computing the rupture degree of a graph is NP-complete. In this paper, we give formulas for the rupture degree of composition of some special graphs and we consider the relationships between the rupture degree and other vulnerability parameters.

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