The Experts below are selected from a list of 4827 Experts worldwide ranked by ideXlab platform
Lloyd S. Davis - One of the best experts on this subject based on the ideXlab platform.
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differences in egg size shell thickness Pore Density Pore diameter and water vapour conductance between first and second eggs of snares penguins eudyptes robustus and their influence on hatching asynchrony
Ibis, 2005Co-Authors: Melanie Massaro, Lloyd S. DavisAbstract:Brood reduction in birds is frequently induced by hatching asynchrony. Crested penguins (genus Eudyptes) are obligate brood reducers, but in contrast to most other birds, first-laid eggs are considerably smaller in size than second-laid eggs; furthermore, first-laid eggs hatch after their siblings. The mechanisms underlying this reversal in size and hatching order remain unclear. In this study, we tested whether the second-laid eggs of Snares Penguins Eudyptes robustus have a higher eggshell porosity allowing them to maintain a higher metabolic rate throughout incubation and to hatch before their first-laid siblings. We investigated differences in egg size, shell thickness, Pore Density, Pore diameter and water vapour conductance between first and second eggs within clutches and examined the influence of these shell characteristics on hatching asynchrony. First-laid eggs of Snares Penguins were approximately 78% of the size of the larger second eggs. Second-laid eggs had considerably thicker shells and more Pores per cm 2 than first eggs, whereas Pore diameter did not differ between eggs. Water vapour conductance was greater in second- (16.8 mg/day/torr) than in first-laid eggs (14.9 mg/day/torr). The difference in water vapour conductance between first- and second-laid eggs within clutches was related to hatching patterns. In nests where second eggs hatched before first-laid eggs, second eggs had a considerably greater water conductance than their sibling, whereas in nests where both eggs hatched on the same day, the difference in water conductance between eggs was very small, and in a few nests where small first eggs hatched before their larger sibling, they had a greater water conductance than their larger second-laid nestmate. Surprisingly few studies have investigated differences in shell characteristics between eggs within clutches and associated effects on hatching asynchrony. This study has demonstrated that such differences exist between eggs within clutches and that they can influence hatching patterns.
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THE INFLUENCE OF LAYING DATE AND MATERNAL AGE ON EGGSHELL THICKNESS AND Pore Density IN YELLOW-EYED PENGUINS
The Condor, 2004Co-Authors: Melanie Massaro, Lloyd S. DavisAbstract:Abstract In many bird species, eggs laid late in the breeding season hatch after a shorter incubation period than eggs that were laid early. The proximate mechanisms that cause these seasonal declines in incubation length remain poorly understood. We tested in Yellow-eyed Penguins (Megadyptes antipodes), Hipfner's hypothesis that late-laid eggs have thinner eggshells with a higher Pore Density that allow embryos to develop more rapidly than in early-laid eggs. In this species incubation length declines with increasing female age, so we also investigated whether eggshell thickness and Pore Density varies with female age. In addition, differences in shell thickness and Pore Density between first- and second-laid eggs of the same clutch were examined. Eggshell thickness did not change with laying date and was not related to length of incubation. In contrast, Pore Density increased with laying date and was negatively related to incubation length in first-laid eggs. Eggshell thickness and Pore Density increase...
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The Influence of Laying Date and Maternal Age on Eggshell Thickness and Pore Density in Yellow-Eyed Penguins
The Condor, 2004Co-Authors: Melanie Massaro, Lloyd S. DavisAbstract:Abstract In many bird species, eggs laid late in the breeding season hatch after a shorter incubation period than eggs that were laid early. The proximate mechanisms that cause these seasonal declines in incubation length remain poorly understood. We tested in Yellow-eyed Penguins (Megadyptes antipodes), Hipfner's hypothesis that late-laid eggs have thinner eggshells with a higher Pore Density that allow embryos to develop more rapidly than in early-laid eggs. In this species incubation length declines with increasing female age, so we also investigated whether eggshell thickness and Pore Density varies with female age. In addition, differences in shell thickness and Pore Density between first- and second-laid eggs of the same clutch were examined. Eggshell thickness did not change with laying date and was not related to length of incubation. In contrast, Pore Density increased with laying date and was negatively related to incubation length in first-laid eggs. Eggshell thickness and Pore Density increased with female age. Second-laid eggs had a lower Pore Density and approximately 900 fewer Pores than first-laid eggs of the same clutch. Our study suggests that embryos of late-laid eggs may be able to develop faster than embryos of early-laid eggs because of a greater capacity for gas exchange. Further work on eggshell porosity could provide answers to some long-standing questions about the evolutionary advantages of seasonal declines in incubation periods and their underlying mechanisms. Influencia de la Fecha de Puesta y Edad Maternal en el Espesor y la Densidad de Poros de la Cáscara de Huevos en Megadyptes antipodes Resumen. En muchas especies de aves, los huevos puestos hacia fines de la estación reproductiva eclosionan luego de un período de incubación más breve que los huevos puestos más temprano. Los mecanismos próximos que causan estas disminuciones estacionales del período de incubación permanecen aún poco entendidos. Aquí evaluamos la hipótesis de Hipfner en Megadyptes antipodes, la cual sostiene que los huevos puestos tardíamente tienen cáscara más delgadas y mayor densidad de poros que los huevos puestos más temprano, lo que permite que los embriones se desarrollen más rápidamente. En esta especie, el período de incubación disminuye a medida que aumenta la edad de la hembra, por lo que también investigamos si el espesor de la cáscara del huevo y la densidad de poros varían con la edad de la hembra. De modo adicional, examinamos las diferencias en el espesor de la cáscara y en la densidad de poros entre huevos de la primera y la segunda puesta dentro de una misma nidada. El espesor de la cáscara del huevo no varió con la fecha de puesta y no se relacionó con la duración del período de incubación. En contraste, la densidad de poros incrementó con la fecha de puesta y se relacionó negativamente con la duración del período de incubación en los huevos de la primera puesta. El espesor de la cáscara y la densidad de poros incrementaron con la edad de la hembra. Los huevos de la segunda puesta tuvieron una densidad de poros menor y aproximadamente 900 poros menos que los huevos de la primera puesta para una misma nidada. Nuestro estudio sugiere que los embriones de huevos puestos tardíamente pueden ser capaces de desarrollarse más rápido que los embriones de huevos puestos tempranamente debido a una mayor capacidad de intercambio de gases. Estudios adicionales de la porosidad de la cáscara del huevo podrían ofrecer respuestas a preguntas irresueltas sobre las ventajas evolutivas de las disminuciones estacionales de los períodos de incubación y sobre sus mecanismos subyacentes.
Nihad Dukhan - One of the best experts on this subject based on the ideXlab platform.
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Impact of Pore Density on oscillating liquid flow in metal foam
Experimental Thermal and Fluid Science, 2018Co-Authors: Özer Bağci, Nihad DukhanAbstract:Abstract Oscillating water flow in commercial, highly-porous, open-cell aluminium foam with two common Pore densities of 10 and 40 Pore per inch (ppi) was investigated experimentally. Flow displacements of 74.35, 97.20 and 111.53 mm were produced in each foam; a sizable range of flow frequency from 0.116 to 0.696 Hz was imposed. The effect of Pore Density was investigated by comparing the two Pore densities of the current study with a third from the literature having 20 ppi. The comparison was at the same porosity of approximately 88%. Results have shown that the Pore Density has a considerable effect on important oscillating water flow parameters including inlet pressure, pressure drop and friction factor. For high frequencies, the 20-ppi foam produced the highest inlet pressure followed by the 40-ppi and then the 10-ppi foam. For low frequencies, the 10-ppi foam produced the highest inlet pressure followed by the 40-ppi foam and then the 20-ppi foam. These trends were explained by considering viscous and form drag pressure losses according to permeabilities and Forchheimer drag coefficients of the three foams. For low frequencies, the pressure drop was periodic for the three Pore densities, while for high frequencies, the periodic behavior of the pressure drop was not clearly discernable, indicating the presence of nonlinear processes and multiple transitions among flow regimes. The friction factor for the oscillating flow was seen to lie above that for steady flow for 10- and 20-ppi foam for all frequencies, as expected. However, there was no difference between the steady-state and oscillating flow friction factors for the 40-ppi foam at low frequencies. The behaviour of friction factors indicated that there was two different regimes based on frequency with the boundary between them occurring at Reynolds number around 4000 for 10- and 20-ppi foams, and at Reynolds number 5500 for the 40-ppi foam. The friction factor correlated with the Reynolds number, with the correlation being generally better for low frequencies. Friction factors for oscillating water flow in metal foam were compared to those obtained for oscillating flow of air and water in some other porous media from the literature. Various effects at play, as well as the interactions among them, were highlighted and discussed. Major conclusions and practical implications were summarized.
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influence of Pore Density on thermal development in open cell metal foam
Experimental Thermal and Fluid Science, 2017Co-Authors: A Arbak, Özer Bağci, Nihad Dukhan, Mustafa OzdemirAbstract:Abstract Herein heat transfer measurements due to water flow in commercial open-cell aluminum foam confined by a cylindrical shell, which was heated by a constant heat flux, are described. Two kinds of commercial foam were tested: 10 and 40 Pores per inch (ppi). Measurements included wall temperature along flow direction as well as average inlet and outlet temperatures of water. Flow rates ranged from Darcy to Forchheimer regimes. The wall temperature along the foam, as well as the local Nusselt number lucidly displayed thermal entry effects leading to thermal fully-developed conditions. The thermal entry length was about 2.9 pipe diameters (150 mm) for 10-ppi and 2.4 pipe diameters (122 mm) for 40-ppi foam; these were same for Darcy and Forchheimer flow regimes. It can be stated that the thermal entry length in open-cell metal foam was found to be significant and different from its porous-media analytically-predicted values and behavior. Moreover, the thermal entry length in metal foam was found to inversely proportional to the Pores Density but in a weak manner.
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experimental hydrodynamics of high porosity metal foam effect of Pore Density
International Journal of Heat and Mass Transfer, 2016Co-Authors: Özer Bağci, Nihad DukhanAbstract:Abstract Commercial open-cell metal foam has very high porosity (often greater than 90%) and a large surface area Density. The open flow area is copious compared to the ligament size. These properties are exploited in many applications, e.g., heat exchanger, reactors and filters. Pressure drop, flow regimes, and transition from one to another, are indispensable for any application involving flow of a fluid through the foam, and for heat transfer rates or reaction paces. These topics are not well-agreed on for foam-like porous media such as metal, graphite and polymeric foams. Pressure drop parameters such as permeability and form/inertial drag coefficients are very divergent for metal foam; the same can be said about flow regime boundaries. This paper presents experimental data for pressure drop for water flow in two commercial open-cell aluminium foams having 10 and 40 Pores per inch (ppi). The two foams have similar porosities (88.5%). The wide range of flow Reynolds number covered all known flow regimes in porous media: pre-Darcy, Darcy, Forchheimer and turbulent. Flow regimes and transition between them were identified and compared. The friction factor based on the square root of permeability (measured in the Darcy regime) and the Reynolds number based on the same characteristic length were used. It is shown that the same foam exhibits different values of its permeability and Forchheimer coefficient in different flow regimes. A previously-tested foam having 20 Pores per inch and a porosity of 87.6% was included in the comparisons. The basic finding of this study will inform numerical and analytical work concerning flow and heat transfer in foam-like highly-porous porous media.
Huiying Wu - One of the best experts on this subject based on the ideXlab platform.
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Size Effects of Pore Density and Solute Size on Water Osmosis through Nanoporous Membrane B
The Journal of Physical Chemistry, 2020Co-Authors: Kuiwen Zhao, Huiying WuAbstract:Understanding the behavior of osmotic transport across nanoporous membranes at molecular level is critical to their design and applications, and it is also beneficial to the comprehension of the mechanism of biological transmembrane transport processes. Pore Density is an important parameter for nanoporous membranes. To better understand the influence of Pore Density on osmotic transport, we have performed systematic molecular dynamics simulations on water osmosis across nanoporous membranes with different Pore densities (i.e., number of Pores per unit area of membrane). The simulation results reveal that significant size effects occur when the Pore Density is so high that the center-to-center distance between neighboring nanoPores is comparable to the solute size. The size effects are independent of the Pore diameter and solute concentration. A simple quantitative correlation between Pore Density, solute size, and osmotic flux has been established. The results are excellently consistent with the theoretical predictions. It is also shown that solute hydration plays an important role in real osmotic processes. Solute hydration strengthens the size effects of Pore Density on osmotic processes due to the enlarged effective solute size induced by hydration. The influence of Pore Density, solute size, and solute hydration on water osmosis through nanoporous membranes can be introduced to eliminate the deviations of real osmotic processes from ideal behavior.
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size effects of Pore Density and solute size on water osmosis through nanoporous membrane
Journal of Physical Chemistry B, 2012Co-Authors: Kuiwen Zhao, Huiying WuAbstract:Understanding the behavior of osmotic transport across nanoporous membranes at molecular level is critical to their design and applications, and it is also beneficial to the comprehension of the mechanism of biological transmembrane transport processes. Pore Density is an important parameter for nanoporous membranes. To better understand the influence of Pore Density on osmotic transport, we have performed systematic molecular dynamics simulations on water osmosis across nanoporous membranes with different Pore densities (i.e., number of Pores per unit area of membrane). The simulation results reveal that significant size effects occur when the Pore Density is so high that the center-to-center distance between neighboring nanoPores is comparable to the solute size. The size effects are independent of the Pore diameter and solute concentration. A simple quantitative correlation between Pore Density, solute size, and osmotic flux has been established. The results are excellently consistent with the theoreti...
Özer Bağci - One of the best experts on this subject based on the ideXlab platform.
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Impact of Pore Density on oscillating liquid flow in metal foam
Experimental Thermal and Fluid Science, 2018Co-Authors: Özer Bağci, Nihad DukhanAbstract:Abstract Oscillating water flow in commercial, highly-porous, open-cell aluminium foam with two common Pore densities of 10 and 40 Pore per inch (ppi) was investigated experimentally. Flow displacements of 74.35, 97.20 and 111.53 mm were produced in each foam; a sizable range of flow frequency from 0.116 to 0.696 Hz was imposed. The effect of Pore Density was investigated by comparing the two Pore densities of the current study with a third from the literature having 20 ppi. The comparison was at the same porosity of approximately 88%. Results have shown that the Pore Density has a considerable effect on important oscillating water flow parameters including inlet pressure, pressure drop and friction factor. For high frequencies, the 20-ppi foam produced the highest inlet pressure followed by the 40-ppi and then the 10-ppi foam. For low frequencies, the 10-ppi foam produced the highest inlet pressure followed by the 40-ppi foam and then the 20-ppi foam. These trends were explained by considering viscous and form drag pressure losses according to permeabilities and Forchheimer drag coefficients of the three foams. For low frequencies, the pressure drop was periodic for the three Pore densities, while for high frequencies, the periodic behavior of the pressure drop was not clearly discernable, indicating the presence of nonlinear processes and multiple transitions among flow regimes. The friction factor for the oscillating flow was seen to lie above that for steady flow for 10- and 20-ppi foam for all frequencies, as expected. However, there was no difference between the steady-state and oscillating flow friction factors for the 40-ppi foam at low frequencies. The behaviour of friction factors indicated that there was two different regimes based on frequency with the boundary between them occurring at Reynolds number around 4000 for 10- and 20-ppi foams, and at Reynolds number 5500 for the 40-ppi foam. The friction factor correlated with the Reynolds number, with the correlation being generally better for low frequencies. Friction factors for oscillating water flow in metal foam were compared to those obtained for oscillating flow of air and water in some other porous media from the literature. Various effects at play, as well as the interactions among them, were highlighted and discussed. Major conclusions and practical implications were summarized.
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influence of Pore Density on thermal development in open cell metal foam
Experimental Thermal and Fluid Science, 2017Co-Authors: A Arbak, Özer Bağci, Nihad Dukhan, Mustafa OzdemirAbstract:Abstract Herein heat transfer measurements due to water flow in commercial open-cell aluminum foam confined by a cylindrical shell, which was heated by a constant heat flux, are described. Two kinds of commercial foam were tested: 10 and 40 Pores per inch (ppi). Measurements included wall temperature along flow direction as well as average inlet and outlet temperatures of water. Flow rates ranged from Darcy to Forchheimer regimes. The wall temperature along the foam, as well as the local Nusselt number lucidly displayed thermal entry effects leading to thermal fully-developed conditions. The thermal entry length was about 2.9 pipe diameters (150 mm) for 10-ppi and 2.4 pipe diameters (122 mm) for 40-ppi foam; these were same for Darcy and Forchheimer flow regimes. It can be stated that the thermal entry length in open-cell metal foam was found to be significant and different from its porous-media analytically-predicted values and behavior. Moreover, the thermal entry length in metal foam was found to inversely proportional to the Pores Density but in a weak manner.
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experimental hydrodynamics of high porosity metal foam effect of Pore Density
International Journal of Heat and Mass Transfer, 2016Co-Authors: Özer Bağci, Nihad DukhanAbstract:Abstract Commercial open-cell metal foam has very high porosity (often greater than 90%) and a large surface area Density. The open flow area is copious compared to the ligament size. These properties are exploited in many applications, e.g., heat exchanger, reactors and filters. Pressure drop, flow regimes, and transition from one to another, are indispensable for any application involving flow of a fluid through the foam, and for heat transfer rates or reaction paces. These topics are not well-agreed on for foam-like porous media such as metal, graphite and polymeric foams. Pressure drop parameters such as permeability and form/inertial drag coefficients are very divergent for metal foam; the same can be said about flow regime boundaries. This paper presents experimental data for pressure drop for water flow in two commercial open-cell aluminium foams having 10 and 40 Pores per inch (ppi). The two foams have similar porosities (88.5%). The wide range of flow Reynolds number covered all known flow regimes in porous media: pre-Darcy, Darcy, Forchheimer and turbulent. Flow regimes and transition between them were identified and compared. The friction factor based on the square root of permeability (measured in the Darcy regime) and the Reynolds number based on the same characteristic length were used. It is shown that the same foam exhibits different values of its permeability and Forchheimer coefficient in different flow regimes. A previously-tested foam having 20 Pores per inch and a porosity of 87.6% was included in the comparisons. The basic finding of this study will inform numerical and analytical work concerning flow and heat transfer in foam-like highly-porous porous media.
Melanie Massaro - One of the best experts on this subject based on the ideXlab platform.
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differences in egg size shell thickness Pore Density Pore diameter and water vapour conductance between first and second eggs of snares penguins eudyptes robustus and their influence on hatching asynchrony
Ibis, 2005Co-Authors: Melanie Massaro, Lloyd S. DavisAbstract:Brood reduction in birds is frequently induced by hatching asynchrony. Crested penguins (genus Eudyptes) are obligate brood reducers, but in contrast to most other birds, first-laid eggs are considerably smaller in size than second-laid eggs; furthermore, first-laid eggs hatch after their siblings. The mechanisms underlying this reversal in size and hatching order remain unclear. In this study, we tested whether the second-laid eggs of Snares Penguins Eudyptes robustus have a higher eggshell porosity allowing them to maintain a higher metabolic rate throughout incubation and to hatch before their first-laid siblings. We investigated differences in egg size, shell thickness, Pore Density, Pore diameter and water vapour conductance between first and second eggs within clutches and examined the influence of these shell characteristics on hatching asynchrony. First-laid eggs of Snares Penguins were approximately 78% of the size of the larger second eggs. Second-laid eggs had considerably thicker shells and more Pores per cm 2 than first eggs, whereas Pore diameter did not differ between eggs. Water vapour conductance was greater in second- (16.8 mg/day/torr) than in first-laid eggs (14.9 mg/day/torr). The difference in water vapour conductance between first- and second-laid eggs within clutches was related to hatching patterns. In nests where second eggs hatched before first-laid eggs, second eggs had a considerably greater water conductance than their sibling, whereas in nests where both eggs hatched on the same day, the difference in water conductance between eggs was very small, and in a few nests where small first eggs hatched before their larger sibling, they had a greater water conductance than their larger second-laid nestmate. Surprisingly few studies have investigated differences in shell characteristics between eggs within clutches and associated effects on hatching asynchrony. This study has demonstrated that such differences exist between eggs within clutches and that they can influence hatching patterns.
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THE INFLUENCE OF LAYING DATE AND MATERNAL AGE ON EGGSHELL THICKNESS AND Pore Density IN YELLOW-EYED PENGUINS
The Condor, 2004Co-Authors: Melanie Massaro, Lloyd S. DavisAbstract:Abstract In many bird species, eggs laid late in the breeding season hatch after a shorter incubation period than eggs that were laid early. The proximate mechanisms that cause these seasonal declines in incubation length remain poorly understood. We tested in Yellow-eyed Penguins (Megadyptes antipodes), Hipfner's hypothesis that late-laid eggs have thinner eggshells with a higher Pore Density that allow embryos to develop more rapidly than in early-laid eggs. In this species incubation length declines with increasing female age, so we also investigated whether eggshell thickness and Pore Density varies with female age. In addition, differences in shell thickness and Pore Density between first- and second-laid eggs of the same clutch were examined. Eggshell thickness did not change with laying date and was not related to length of incubation. In contrast, Pore Density increased with laying date and was negatively related to incubation length in first-laid eggs. Eggshell thickness and Pore Density increase...
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The Influence of Laying Date and Maternal Age on Eggshell Thickness and Pore Density in Yellow-Eyed Penguins
The Condor, 2004Co-Authors: Melanie Massaro, Lloyd S. DavisAbstract:Abstract In many bird species, eggs laid late in the breeding season hatch after a shorter incubation period than eggs that were laid early. The proximate mechanisms that cause these seasonal declines in incubation length remain poorly understood. We tested in Yellow-eyed Penguins (Megadyptes antipodes), Hipfner's hypothesis that late-laid eggs have thinner eggshells with a higher Pore Density that allow embryos to develop more rapidly than in early-laid eggs. In this species incubation length declines with increasing female age, so we also investigated whether eggshell thickness and Pore Density varies with female age. In addition, differences in shell thickness and Pore Density between first- and second-laid eggs of the same clutch were examined. Eggshell thickness did not change with laying date and was not related to length of incubation. In contrast, Pore Density increased with laying date and was negatively related to incubation length in first-laid eggs. Eggshell thickness and Pore Density increased with female age. Second-laid eggs had a lower Pore Density and approximately 900 fewer Pores than first-laid eggs of the same clutch. Our study suggests that embryos of late-laid eggs may be able to develop faster than embryos of early-laid eggs because of a greater capacity for gas exchange. Further work on eggshell porosity could provide answers to some long-standing questions about the evolutionary advantages of seasonal declines in incubation periods and their underlying mechanisms. Influencia de la Fecha de Puesta y Edad Maternal en el Espesor y la Densidad de Poros de la Cáscara de Huevos en Megadyptes antipodes Resumen. En muchas especies de aves, los huevos puestos hacia fines de la estación reproductiva eclosionan luego de un período de incubación más breve que los huevos puestos más temprano. Los mecanismos próximos que causan estas disminuciones estacionales del período de incubación permanecen aún poco entendidos. Aquí evaluamos la hipótesis de Hipfner en Megadyptes antipodes, la cual sostiene que los huevos puestos tardíamente tienen cáscara más delgadas y mayor densidad de poros que los huevos puestos más temprano, lo que permite que los embriones se desarrollen más rápidamente. En esta especie, el período de incubación disminuye a medida que aumenta la edad de la hembra, por lo que también investigamos si el espesor de la cáscara del huevo y la densidad de poros varían con la edad de la hembra. De modo adicional, examinamos las diferencias en el espesor de la cáscara y en la densidad de poros entre huevos de la primera y la segunda puesta dentro de una misma nidada. El espesor de la cáscara del huevo no varió con la fecha de puesta y no se relacionó con la duración del período de incubación. En contraste, la densidad de poros incrementó con la fecha de puesta y se relacionó negativamente con la duración del período de incubación en los huevos de la primera puesta. El espesor de la cáscara y la densidad de poros incrementaron con la edad de la hembra. Los huevos de la segunda puesta tuvieron una densidad de poros menor y aproximadamente 900 poros menos que los huevos de la primera puesta para una misma nidada. Nuestro estudio sugiere que los embriones de huevos puestos tardíamente pueden ser capaces de desarrollarse más rápido que los embriones de huevos puestos tempranamente debido a una mayor capacidad de intercambio de gases. Estudios adicionales de la porosidad de la cáscara del huevo podrían ofrecer respuestas a preguntas irresueltas sobre las ventajas evolutivas de las disminuciones estacionales de los períodos de incubación y sobre sus mecanismos subyacentes.