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All sourcesNASA NTRSDOE OSTI
NASA NTRSDate not supplied

On Improving the Dust Lidar Ratios for Version 5 of CALIOP by Using Measurements with Source-tagged Model Results

Vertically resolved retrievals of aerosol backscatter and extinction have been available since 2006 from global measurements acquired by the space borne lidar CALIOP onboard the CALIPSO satellite. These retrievals depend crucially upon the ratio of extinction to backscatter (i.e., lidar ratio) which typically has to be assumed for the various aerosol species for an elastic backscatter lidar like CALIOP. For all CALIPSO data releases up until now (version 4.2), these lidar ratios have been taken as constant both spatially and temporally. However, it is well established that the aerosol lidar ratios can vary significantly regionally, seasonally, and also as a function of age and relative humidity. In particular, the dust lidar ratios show significant variation depending upon their source regions, which is related to the mineral composition of dust in that region. In this paper, we shall present a scheme to obtain the regionally and seasonally dependent lidar ratios of dust. In this scheme, which may be implemented in a forthcoming version of CALIOP aerosol extinction retrievals, we first derive lidar ratios of aerosol layers globally, classified as dust by CALIOP, by using the backscatter measurements constrained by collocated MODIS aerosol optical depths. Since this dust will frequently be a mixture of dust from various source regions, we obtain the corresponding regional contributions from the dust simulations using the GEOS model tagged to nine source regions. Finally, combining information from both measurements and models, we obtain the lidar ratios of dust corresponding to the nine source regions. The lidar ratio of the mixed dust anywhere can now be obtained from the tagged model fractions and the corresponding regional lidar ratio. We shall show the application of this scheme for various regions and seasons.

CALIPSO↗
DOE OSTI2020

Effects of molar expansion ratio of fuels on engine efficiency

Fuel properties have a strong impact on the efficiency of internal combustion engines. Contrary to other physical and thermochemical fuel properties, the molar expansion ratio is normally ignored. Molar expansion ratio is the ratio of number of moles of the products to the reactants. In this work, the impact of the fuel’s molar expansion ratio on engine efficiency is investigated. Findings are based on simulations of a spark ignition engine using different fuels (standard fuels and user-defined fuels) and different dilution ratios. Simulations without heat transfer and friction were performed first. The combustion then takes place at top dead center with a very short combustion duration to approach the ideal Otto cycle. The heat transfer and friction were then added step by step. From this analysis, it could be concluded that the heat loss and friction work decrease as molar expansion ratio increases. The gross indicated and brake thermal efficiencies thus increase. User-defined fuels with different molar expansion ratio, but the same physical and thermochemical properties were then employed. The simulated results showed that the brake thermal efficiency increases by around 1.15% with an increase in molar expansion ratio of 0.02 compared to a fuel with a molar expansion ratio of unity. Lastly, the simulation was also done with air and exhaust gas recirculation dilution.

42 ENGINEERING↗
DOE OSTI2021

Comparison of methodologies used to determine aromatic lignin unit ratios in lignocellulosic biomass

Abstract Background Multiple analytical methods have been developed to determine the ratios of aromatic lignin units, particularly the syringyl/guaiacyl (S/G) ratio, of lignin biopolymers in plant cell walls. Chemical degradation methods such as thioacidolysis produce aromatic lignin units that are released from certain linkages and may induce chemical changes rendering it difficult to distinguish and determine the source of specific aromatic lignin units released, as is the case with nitrobenzene oxidation methodology. NMR methods provide powerful tools used to analyze cell walls for lignin composition and linkage information. Pyrolysis-mass spectrometry methods are also widely used, particularly as high-throughput methodologies. However, the different techniques used to analyze aromatic lignin unit ratios frequently yield different results within and across particular studies, making it difficult to interpret and compare results. This also makes it difficult to obtain meaningful insights relating these measurements to other characteristics of plant cell walls that may impact biomass sustainability and conversion metrics for the production of bio-derived fuels and chemicals. Results The authors compared the S/G lignin unit ratios obtained from thioacidolysis, pyrolysis-molecular beam mass spectrometry (py-MBMS), HSQC liquid-state NMR and solid-state (ss) NMR methodologies of pine, several genotypes of poplar, and corn stover biomass. An underutilized approach to deconvolute ssNMR spectra was implemented to derive S/G ratios. The S/G ratios obtained for the samples did not agree across the different methods, but trends were similar with the most agreement among the py-MBMS, HSQC NMR and deconvoluted ssNMR methods. The relationship between S/G, thioacidolysis yields, and linkage analysis determined by HSQC is also addressed. Conclusions This work demonstrates that different methods using chemical, thermal, and non-destructive NMR techniques to determine native lignin S/G ratios in plant cell walls may yield different results depending on species and linkage abundances. Spectral deconvolution can be applied to many hardwoods with lignin dominated by S and G units, but the results may not be reliable for some woody and grassy species of more diverse lignin composition. HSQC may be a better method for analyzing lignin in those species given the wealth of information provided on additional aromatic moieties and bond linkages. Additionally, trends or correlations in lignin characteristics such as S/G ratios and lignin linkages within the same species such as poplar may not necessarily exhibit the same trends or correlations made across different biomass types. Careful consideration is required when choosing a method to measure S/G ratios and the benefits and shortcomings of each method discussed here are summarized.

09 BIOMASS FUELS↗
DOE OSTI2022

The flux ratio of the [N II] λ λ 6548, 6583 Å lines in sample of Active Galactic Nuclei Type 2

In spectra of the Active Galactic Nuclei (AGNs), the [N II]λλ 6548, 6583 Å lines are commonly fitted using the fixed intensity ratio of these two lines (R [NII] = I 6583 /I 6548 ). However, the used values for fixed intensity ratio are slightly different through literature. There are several theoretical calculations of the transition probabilities which can be used for the line ratio estimation, but there are no experimental measurements of this ratio, since the [N II] lines are extremely weak in laboratory plasma. Therefore, the intensity ratio of [N II] lines can be measured only in the spectra of astrophysical objects. However, precise and systematic measurements have not be done so far, because of difficulties in measurement of the [N II] ratio in various spectra (overlapping with Hα, weak intensity of [N II], influence of the continuum noise and outflow contribution, etc.). Here we present the measurements of the flux ratio of the [N II] λλ 6548, 6583 Å emission lines for a sample of 250 Type 2 AGNs spectra taken form Sloan Digital Sky Survey (SDSS) data base. Further, the spectra are chosen to have high signal-to-noise ratio and to [N II] and Hα lines do not overlap. The obtained mean flux ratio from measurements is 3.049 ± 0.021. Our result is in agreement with theoretical result obtained by taking into account the relativistic corrections to the magnetic dipole operator.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2023

Erratum: Monoenergetic photon-induced fission cross-section ratio measurements for U 235 , U 238 , and Pu 239 from 9.0 to 17.0 MeV

In this erratum we report a correction to the previously published photofission cross-section ratio data. The actinide fission-chamber foils utilized in this work were extensively characterized during a new campaign using α- and γ-ray spectroscopy, and 2π alpha counting. These three techniques agreed, resulting in an improved accuracy of the fission-chamber foil masses used in the original experiment. The foil masses measured by α spectroscopy are detailed in Table I. All foils were counted on the same α spectrometer, using an identical geometry, which reduces the systematic uncertainty in the calculated mass ratios since the α spectrometer efficiency cancels out in the ratio. This results in a relative uncertainty on the mass ratio of 1.0% for 235 U/ 238 U, 0.62% for 239 Pu/ 235 U, and 1.1% for 239 Pu/ 238 U. The published cross-section ratio data are re-calculated to reflect the updated target masses and uncertainties. The new mass values cause a 2.40% decrease for the σ( 235 U(γ, f)/ 238 U(γ, f)) ratio, a 5.10% decrease for the σ( 235 U(γ, f)/ 239 Pu(γ, f)) ratio, and a 2.77% decrease for the σ( 238 U(γ, f)/ 239 Pu(γ, f)) ratio. The updated cross-section ratios are presented in Tables II, III, and IV, which are corrected versions of Tables III, IV, and V in Ref. [1]

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2021

Influences of pH and substrate supply on the ratio of iron to sulfate reduction

Iron reduction and sulfate reduction often occur simultaneously in anoxic systems, and where that is the case, the molar ratio between the reactions (i.e., Fe/SO 4 2- reduced) influences their impact on water quality and carbon storage. Previous research has shown that pH and the supply of electron donors and acceptors affect that ratio, but it is unclear how their influences compare and affect one another. This study examines impacts of pH and the supply of acetate, sulfate, and goethite on the ratio of iron to sulfate reduction in semi-continuous sediment bioreactors. We examined which parameter had the greatest impact on that ratio and whether the parameter influences depended on the state of each other. Results show that pH had a greater influence than acetate supply on the ratio of iron to sulfate reduction, and that the impact of acetate supply on the ratio depended on pH. In acidic reactors (pH 6.0 media), the ratio of iron to sulfate reduction decreased from 3:1 to 2:1 as acetate supply increased (0-1 mM). In alkaline reactors (pH 7.5 media), iron and sulfate were reduced in equal proportions, regardless of acetate supply. Secondly, a comparison of experiments with and without sulfate shows that the extent of iron reduction was greater if sulfate reduction was occurring and that the effect was larger in alkaline reactors than acidic reactors. Thus, the influence of sulfate supply on iron reduction extent also depended on pH and suggests that iron reduction grows more dependent on sulfate reduction as pH increases. Our results compare well to trends in groundwater geochemistry and provide further evidence that pH is a major control on iron and sulfate reduction in systems with crystalline (oxyhydr)oxides. pH not only affects the ratio between the reactions but also the influences of other parameters on that ratio.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2022

Dependence of the Ratio of Total to Visible Mass on Observable Properties of Sloan Digital Sky Survey MaNGA Galaxies

Abstract Using spectroscopic observations from the Sloan Digital Sky Survey Mapping Nearby Galaxies at Apache Point Observatory Data Release 15, we study the relationships between the ratio of total to visible mass and various parameters characterizing the evolution and environment of the galaxies in this survey. Measuring the rotation curve with the relative velocities of the H α emission line across a galaxy’s surface, we estimate each galaxy’s total mass. We develop a statistical model to describe the observed distribution in the ratio of total to visible mass, from which we extract the most probable value of this mass ratio for a given sample of galaxies. We present the relationships between the ratio of total to visible mass and several characteristics describing galactic evolution, such as luminosity, gas-phase metallicity, distance to the nearest neighbor, and position on the color–magnitude diagram. We find that faint galaxies with low metallicities, typically in the blue cloud, have the highest ratios of total to visible mass. This mass ratio is significantly reduced when we include the H i mass in the total visible mass, implying that feedback mechanisms are not as strong in low-mass galaxies as previously thought. Those galaxies that exhibit the second-highest ratios of total to visible mass are the brightest with high metallicities, typically members of the red sequence or green valley. Active galactic nucleus activity is likely both the quenching mechanism and the feedback that drives the mass ratio higher in these massive galaxies. Finally, we introduce a parameterization that predicts a galaxy’s ratio of total to visible mass based only on its photometry and luminosity.

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS1973

Effects of fineness and closure ratios on boattail drag of circular-arc-afterbody models with jet exhaust at Mach numbers up to 1.3

The effects of variations in fineness ratio and closure ratio on the boattail drag of circular-arc afterbody models were investigated at static conditions and at Mach numbers from 0.40 to 1.30. Jet total-pressure ratio was varied from jet off to about 6, depending on Mach number. Reynolds number based on model maximum diameter varied from about 1.2 million to 2.18 million. Angle of attack was varied from -4 deg to 8 deg. The results indicate that, at subsonic speeds before the drag rise and at a scheduled pressure ratio, the total drag (pressure plus calculated skin friction) is approximately equal for configurations with the same closure ratio. Also, for configurations with the same closure ratio, increasing fineness ratio results in an increased drag-rise Mach number; and for configurations with the same fineness ratio, increasing closure ratio results in an increased drag-rise Mach number.

Reubush, D. E.↗
NASA NTRS1975

An investigation of several NACA 1-series inlets at Mach numbers from 0.4 to 1.29 for mass flow ratios near 1.0

An investigation to determine the performance of eight NACA 1-series inlets at massflow ratios near 1.0 was conducted in the Langley 16-foot transonic tunnel. The inlet diameter ratios (ratio of inlet diameter to maximum diameter) were 0.85 and 0.89 for an inlet length ratio (ratio of inlet length to maximum diameter) of 1.0. Inlet lip radius varied from 0.061 cm to 0.251 cm, and internal contraction area ratio (ratio of inlet area to throat area) varied from 1.006 to 1.201. Reynolds number based on model maximum diameter ranged from 3,600,000 at a Mach number of 400,000 to 5,900,000 at a Mach number of 1.29. The results indicate that nearly uniform pressure distributions on a given inlet were obtained over a limited range of mass-flow ratios and Mach numbers. When inlet lip thickness was increased by means of lip radius or contraction ratio, the inlet critical Mach number decreased. Drag-divergence Mach number inferred from forebody pressure integrations was above 0.94 for most of the inlets tested.

Re, R. J.↗
NASA NTRS1991

A reevaluation of spectral ratios for lunar mare TiO2 mapping

The empirical relation established by Charette et al. (1974) between the 400/560-nm spectral ratio of mature mare soils and weight percent TiO2 has been used extensively to map titanium content in the lunar maria. Relative reflectance spectra of mare regions show that a reference wavelength further into the near-IR, e.g., above 700 nm, could be used in place of the 560-nm band to provide greater contrast (a greater range of ratio values) and hence a more sensitive indicator of titanium content. An analysis of 400/730-nm ratio values derived from both laboratory and telescopic relative reflectance spectra suggests that this ratio provides greater sensitivity to TiO2 content than the 400/560-nm ratio. The increased range of ratio values is manifested in higher contrast 400/730-nm ratio images compared to 400/560-nm ratio images. This potential improvement in sensivity encourages a reevaluation of the original Charette et al. (1974) relation using the 400/730-nm ratio.

Johnson, Jeffrey R.↗
NASA NTRS1992

Ruthenium/Iridium Ratios in the Cretaceous-tertiary Boundary Clay: Implications for Global Dispersal and Fractionation Within the Ejecta Cloud

Ruthenium (Ru) and iridium (Ir) are the least mobile platinum group elements (PGE's) within the Cretaceous-Tertiary (K-T) boundary clay (BC). The Ru/Ir ratio is, therefore, the most useful PGE interelement ratio for distinguishing terrestrial and extraterrestrial contributions to the BC. The Ru/Ir ratio of marine K-T sections (1.77 +/- 0.53) is statistically different from that of the continental sections (0.93 +/- 0.28). The marine Ru/Ir ratios are chondritic (C1 = 1.48 +/- 0.09), but the continental ratios are not. We discovered an inverse correlation of shocked quartz size (or distance from the impact site) and Ru/Ir ratio. This correlation may arise from the difference in Ru and Ir vaporization temperature and/or fractionation during condensation from the ejecta cloud. Postsedimentary alteration, remobilization, or terrestrial PGE input may be responsible for the Ru/Ir ratio variations within the groups of marine and continental sites studied. The marine ratios could also be attained if approximately 15 percent of the boundary metals were contributed by Deccan Trap emissions. However, volcanic emissions could not have been the principal source of the PGE's in the BC because mantle PGE ratios and abundances are inconsistent with those measured in the clay. The Ru/Ir values for pristine Tertiary mantle xenoliths (2.6 +/- 0.48), picrites (4.1 +/- 1.8), and Deccan Trap basalt (3.42 +/- 1.96) are all statistically distinct from those measured in the K-T BC.

Evans, Noreen Joyce↗
NASA NTRS1992

A neural network-based estimator for the mixture ratio of the Space Shuttle Main Engine

In order to properly utilize the available fuel and oxidizer of a liquid propellant rocket engine, the mixture ratio is closed loop controlled during main stage (65 percent - 109 percent power) operation. However, because of the lack of flight-capable instrumentation for measuring mixture ratio, the value of mixture ratio in the control loop is estimated using available sensor measurements such as the combustion chamber pressure and the volumetric flow, and the temperature and pressure at the exit duct on the low pressure fuel pump. This estimation scheme has two limitations. First, the estimation formula is based on an empirical curve fitting which is accurate only within a narrow operating range. Second, the mixture ratio estimate relies on a few sensor measurements and loss of any of these measurements will make the estimate invalid. In this paper, we propose a neural network-based estimator for the mixture ratio of the Space Shuttle Main Engine. The estimator is an extension of a previously developed neural network based sensor failure detection and recovery algorithm (sensor validation). This neural network uses an auto associative structure which utilizes the redundant information of dissimilar sensors to detect inconsistent measurements. Two approaches have been identified for synthesizing mixture ratio from measurement data using a neural network. The first approach uses an auto associative neural network for sensor validation which is modified to include the mixture ratio as an additional output. The second uses a new network for the mixture ratio estimation in addition to the sensor validation network. Although mixture ratio is not directly measured in flight, it is generally available in simulation and in test bed firing data from facility measurements of fuel and oxidizer volumetric flows. The pros and cons of these two approaches will be discussed in terms of robustness to sensor failures and accuracy of the estimate during typical transients using simulation data.

Guo, T. H.↗
NASA NTRS1997

The Effect of Cooling Passage Aspect Ratio on Curvature Heat Transfer Enhancement

A series of electrically heated tube experiments was performed to investigate the effect of high aspect ratio on curvature heat transfer enhancement in uniformly heated rectangular cooling passages. Three hardware geometries were tested: a baseline straight aspect ratio 10 tube, an aspect ratio 1 (square) tube with a 45 deg. curve, and an aspect ratio 10 tube with a 45 deg. curve. Gaseous nitrogen with the following properties was used as the coolant: ambient inlet temperature, pressures to 8.3 MPa, wall-to-bulk temperature ratios less than two, and Reynolds numbers based on hydraulic diameter ranging from 250,000 to 1,600,000. The measured curvature enhancement factors were compared to values predicted by three previously published models which had been developed for low aspect ratio tubes. The models were shown to be valid for the high aspect ratio tube as well the low aspect ratio tube, indicating that aspect ratio had little impact on the curvature heat transfer enhancement in these tests.

Meyer, Michael L.↗
NASA NTRS1961

Aerodynamic Characteristics of Low-Aspect-Ratio Wings in Close Proximity to the Ground

A wind-tunnel investigation has been conducted to determine the effect of ground proximity on the aerodynamic characteristics of thick highly cambered rectangular wings with aspect ratios of 1. 2, 4, and 6. The results showed that, for these aspect ratios, as the ground war, approached all wings experienced increases in lift-curve slope and reductions in induced drag which resulted in increases in lift-drag ratio. Although an increase in lift-curve slope was obtained for all aspect ratios as the ground was approached, the lift coefficient at an angle of attack of 0 deg for any given aspect ratio remained nearly constant. The experimental results were in general agreement with Wieselsberger's ground-effect theory (NACA Technical Memorandum 77). As the wings approached the ground, there was an increase in static longitudinal stability at positive angles of attack. When operating in ground effect, all the wings had stability of height at positive angles of attack and instability of height at negative angles of attack. Wing-tip fairings on the wings with aspect ratios of 1 and 2 produced small increases in lift-drag ratio in ground effect. End plates extending only below the chord plane on the wing with an aspect ratio of 1 provided increases in lift coefficient and in lift-drag ratio in ground effect.

Fink, Marvin P.↗
NASA NTRS1951

Aerodynamic Characteristics of a Flying-Boat Hull Having a Length-Beam Ratio of 15, TED No. NACA 2206

An investigation was made in the Langley 300 MPH 7- by 10-foot tunnel to determine the aerodynamic characteristics of a flying-boat hull of a length-beam ratio of 15 in the presence of a wing. The investigation was an extension of previous tests made on hulls of length-beam ratios of 6, 9, and 12; these hulls were designed to have approximately the same hydrodynamic performance with respect to spray and resistance characteristics. Comparison with the previous investigation at lower length-beam ratios indicated a reduction in minimum drag coefficients of 0.0006 (10 peroent)with fixed transition when the length-beam ratio was extended from 12 to 15. As with the hulls of lower length-beam ratio, the drag reduction with a length-beam ratio of 15 occurred throughout the range of angle of attack tested and the angle of attack for minimum drag was in the range from 2deg to 3deg. Increasing the length-beam ratio from 12 to 15 reduced the hull longitudinal instability by an mount corresponding to an aerodynamic-center shift of about 1/2 percent of the mean aerodynamic chord of the hypothetical flying boat. At an angle of attack of 2deg, the value of the variation of yawing-moment coefficient with angle of yaw for a length-beam ratio of 15 was 0.00144, which was 0.00007 larger than the value for a length-beam ratio of 12.

Riebe, John M.↗
NASA NTRS2012

Combining Ratio Estimation for Low Density Parity Check (LDPC) Coding

The Low Density Parity Check (LDPC) Code decoding algorithm make use of a scaled receive signal derived from maximizing the log-likelihood ratio of the received signal. The scaling factor (often called the combining ratio) in an AWGN channel is a ratio between signal amplitude and noise variance. Accurately estimating this ratio has shown as much as 0.6 dB decoding performance gain. This presentation briefly describes three methods for estimating the combining ratio: a Pilot-Guided estimation method, a Blind estimation method, and a Simulation-Based Look-Up table. The Pilot Guided Estimation method has shown that the maximum likelihood estimates of signal amplitude is the mean inner product of the received sequence and the known sequence, the attached synchronization marker (ASM) , and signal variance is the difference of the mean of the squared received sequence and the square of the signal amplitude. This method has the advantage of simplicity at the expense of latency since several frames worth of ASMs. The Blind estimation method s maximum likelihood estimator is the average of the product of the received signal with the hyperbolic tangent of the product combining ratio and the received signal. The root of this equation can be determined by an iterative binary search between 0 and 1 after normalizing the received sequence. This method has the benefit of requiring one frame of data to estimate the combining ratio which is good for faster changing channels compared to the previous method, however it is computationally expensive. The final method uses a look-up table based on prior simulated results to determine signal amplitude and noise variance. In this method the received mean signal strength is controlled to a constant soft decision value. The magnitude of the deviation is averaged over a predetermined number of samples. This value is referenced in a look up table to determine the combining ratio that prior simulation associated with the average magnitude of the deviation. This method is more complicated than the Pilot-Guided Method due to the gain control circuitry, but does not have the real-time computation complexity of the Blind Estimation method. Each of these methods can be used to provide an accurate estimation of the combining ratio, and the final selection of the estimation method depends on other design constraints.

Mahmoud, Saad↗
DOE OSTI2021

Exploring the Effects of Emplacement Conditions on Explosion P/S Ratios across Local to Regional Distances

High-frequency (~> 2 Hz) seismic P/S amplitude ratios are well-established as a discriminant to distinguish between natural earthquakes and underground explosions at regional distances (~200–1500 km). As research shifts toward identifying lower-yield events, work has begun to investigate the potential of this discriminant for use at local distances (<200 km), in which initial results raise questions about its effectiveness. Here, we utilize data from several chemical explosion experiment series at the Nevada National Security Site in southern Nevada in the United States to study explosion Pg/Lg ratios across the range of local to regional distances. Additionall, the experiments are conducted over differing emplacement conditions, with contrasting geologies and a variety of yields and depths of burial, including surface explosions. We first establish the similarities of Pg/Lg ratios from chemical explosions to those from historic nuclear tests and conclude that, as previous data have suggested, chemical explosion ratios are good proxies for nuclear tests. We then examine Pg/Lg ratios from the new experiment series as functions of distance, yield, depth of burial, and scaled depth of burial (SDOB). At far-local and regional distances, we observe consistently higher ratios from hard-rock explosions compared to ones in a weaker dry alluvium medium, consistent with prior regional distance results. No other trends with yield, depth of burial, or SDOB are strongly evident. Scatter in the observed ratios is very high, particularly at the shortest event-to-station distances, suggesting that small-scale path effects play a significant role. On average, the local distance explosion Pg/Lg ratios show remarkable consistency across all the variations in emplacement. Explosion source models will need to reproduce these results.

58 GEOSCIENCES↗
DOE OSTI2023

Variance in offspring sex ratio and maternal allocation in a highly invasive mammal

Abstract Skewed sex ratios at birth are widely reported in wild populations, however, the extent to which parents are able to modulate the sex ratio of offspring to maximize their own fitness remains unclear. This is particularly true for highly polytocous species as maximizing fitness may include trade‐offs between sex ratio and the size and number of offspring in litters. In such cases, it may be adaptive for mothers to adjust both the number of offspring per litter and offspring sex to maximize individual fitness. Investigating maternal sex allocation in wild pigs ( Sus scrofa ) under stochastic environmental conditions, we predicted that under favorable conditions, high‐quality mothers (larger and older) would produce male‐biased litters and invest more in producing larger litters with more males. We also predicted sex ratio would vary relative to litter size, with a male‐bias among smaller litters. We found evidence that increasing wild boar ancestry, maternal age and condition, and resource availability may weakly contribute to male‐biased sex ratio, however, unknown factors not measured in this study are assumed to be more influential. High‐quality mothers allocated more resources to litter production, but this relationship was driven by adjustment of litter size, not sex ratio. There was no relationship between sex ratio and litter size. Collectively, our results emphasized that adjustment of litter size appeared to be the primary reproductive characteristic manipulated in wild pigs to increase fitness rather than adjustment of offspring sex ratio.

59 BASIC BIOLOGICAL SCIENCES↗