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41.
This study comprehensively characterizes hourly fine particulate matter (PM(2.5)) concentrations measured via a tapered element oscillating microbalance (TEOM), beta-gauge, and nephelometer from four different monitoring sites in U.S. Environment Protection Agency (EPA) Region 5 (in U.S. states Illinois, Michigan, and Wisconsin) and compares them to the Federal Reference Method (FRM). Hourly characterization uses time series and autocorrelation. Hourly data are compared with FRM by averaging across 24-hr sampling periods and modeling against respective daily FRM concentrations. Modeling uses traditional two-variable linear least-squares regression as well as innovative nonlinear regression involving additional meteorological variables such as temperature and humidity. The TEOM shows a relationship with season and temperature, linear correlation as low as 0.7924 and nonlinear model correlation as high as 0.9370 when modeled with temperature. The beta-gauge shows no relationship with season or meteorological variables. It exhibits a linear correlation as low as 0.8505 with the FRM and a nonlinear model correlation as high as 0.9339 when modeled with humidity. The nephelometer shows no relationship with season or temperature but a strong relationship with humidity is observed. A linear correlation as low as 0.3050 and a nonlinear model correlation as high as 0.9508 is observed when modeled with humidity. Nonlinear models have higher correlation than linear models applied to the same dataset. This correlation difference is not always substantial, which may introduce a tradeoff between simplicity of model and degree of statistical association. This project shows that continuous monitor technology produces valid PM(2.5) characterization, with at least partial accounting for variations in concentration from gravimetric reference monitors once appropriate nonlinear adjustments are applied. Although only one regression technically meets new EPA National Ambient Air Quality Standards (NAAQS) Federal Equivalent Method (FEM) correlation coefficient criteria, several others are extremely close, showing optimistic potential for use of this nonlinear adjustment model in garnering EPA NAAQS FEM approval for continuous PM(2.5) sampling methods. 相似文献
42.
Male willow warblers have song repertoires which vary in complexity along several dimensions. We examined whether female choice,
as measured by date of pairing, was based on these song characteristics in 4 different years. Pairing date was negatively
correlated with song repertoire size in 1 year, and with song versatility in another year, but there was no consistent effect
of any song characteristic on pairing throughout the years or in the pooled sample. The variable that best explained how soon
a male pairs is male arrival date (only males that had settled territories before the first female arrived were considered
in the analysis). This correlation is consistently significant in all years. This is most parsimoniously interpreted as females
choosing some habitat characteristic in the same way that males do. A small percentage of males (8.3%) attracted and paired
with a second female. The likelihood of becoming polygynous was not explained by any measured song characteristic, but it
was related to arrival date: early males were more likely to pair with two females. Males with large repertoires fledged more
young in their primary nests, and there was a trend for the offspring of these males to have a greater probability of being
recruited into the population. In conclusion, the results show that in most years there is no sexual selection by female preference
on song characteristics, although the data on reproductive success is consistent with the idea of repertoire size being an
indicator of male quality.
Received: 4 June 1999 / Received in revised form: 1 December 1999 / Accepted: 31 December 1999 相似文献
43.
Utility of North Atlantic Right Whale Museum Specimens for Assessing Changes in Genetic Diversity 总被引:2,自引:0,他引:2
Howard C. Rosenbaum †§§ Mary G. Egan Phillip J. Clapham ‡ Robert L. Brownell JR. § Sobia Malik Moira W. Brown ††‡‡ Bradley N. White Peter Walsh † and Rob Desalle 《Conservation biology》2000,14(6):1837-1842
Abstract: We examined six historical specimens of the endangered North Atlantic right whale ( Eubalaena glacialis ) using DNA isolated from documented baleen plates from the late nineteenth and early twentieth centuries. Sequences from the mitochondrial DNA (mtDNA) control region from these samples were compared with those from a near-exhaustive survey (269 of approximately 320 individuals) of the remaining right whales in the western North Atlantic Ocean. Our results suggest that there has been only relatively modest change in maternal lineage diversity over the past century in the North Atlantic right whale population. Any significant reduction in genetic variation in the species most likely occurred prior to the late nineteenth century. One historical specimen was from the last documented female capable of propagating one of the maternal lineages in the population today; no females in the existing population have been found to carry this mtDNA haplotype. Analysis of the only specimens from the eastern North Atlantic right whale population ever to be examined revealed that eastern and western North Atlantic right whales may not have been genetically differentiated populations. Loss of gene diversity experienced by North Atlantic right whales over the last century has been modest, and the six decades of protection have been successful in maintaining much of the maternal lineage diversity that was present in the late nineteenth century. 相似文献
44.
Different mechanisms downstream from high temperature processes lead to the formation of polychlorinated dibenzo(p) dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs). Independent from any concentrations, these mechanisms cause comparable PCDD/F patterns, the percentage proportion of single congeners or homologous groups related to the total of 17 2,3,7,8-Cl-substituted congeners or with respect to the sum of the homologous groups tetra to octa CDD/F. The characteristics of these so-called “combustion profiles” can help to interpret corresponding data from burning and melting facilities, such as municipal waste incinerators, coal power plants, sintering plants, metal finishing facilities, cement kilns, crematoria, hazardous waste incinerators and landfill gas burners 相似文献
45.
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48.
Maternal investment in rhesus macaques (Macaca mulatta): reproductive costs and consequences of raising sons 总被引:1,自引:0,他引:1
Maternal investment in offspring is expected to vary according to offspring sex when the reproductive success of the progeny
is a function of differential levels of parental expenditure. We conducted a longitudinal investigation of rhesus macaques
to determine whether variation in male progeny production, measured with both DNA fingerprinting and short tandem repeat marker
typing, could be traced back to patterns of maternal investment. Males weigh significantly more than females at birth, despite
an absence of sex differences in gestation length. Size dimorphism increases during infancy, with maternal rank associated
with son’s, but not daughter’s, weight at the end of the period of maternal investment. Son’s, but not daughter’s, weight
at 1 year of age is significantly correlated with adult weight, and male, but not female, weight accounts for a portion of
the variance in reproductive success. Variance in annual offspring output was three- to fourfold higher in males than in females.
We suggest that energetic costs of rearing sons could be buffered by fetal delivery of testosterone to the mother, which is
aromatized to estrogen and fosters fat accumulation during gestation. We conclude that maternal investment is only slightly
greater in sons than in daughters, with mothers endowing sons with extra resources because son, but not daughter, mass has
ramifications for offspring sirehood. However, male reproductive tactics supersede maternal investment patterns as fundamental
regulators of male fitness.
Received: 23 July 1999 / Received in revised form: 23 February 2000 / Accepted: 13 March 2000 相似文献
49.
James V. Briskie Robert Montgomerie Tarmo Põldmaa Peter T. Boag 《Behavioral ecology and sociobiology》1998,43(3):181-190
In species where females copulate with more than one male during a single breeding attempt, males risk investing in offspring
that are not their own. In the polygynandrous Smith's longspur (Calcarius pictus), females copulate sequentially with one to three males for each clutch of eggs and most of these males later assist in feeding
the young. Using multilocus DNA profiling, we determined that there was mixed paternity in >75% of broods (n=31) but that few offspring (<1% of 114 nestlings) were sired by males outside the polygynandrous group. Male feeding rate
increased significantly with the number of young sired, with males siring four nestlings feeding the brood at double the frequency
of males siring only a single nestling. However, male Smith's longspurs appear to show a graded adjustment of paternal care
in response to paternity only when other males are available to compensate for reduced care: feeding rate did not vary in
relation to paternity when only one male provisioned young at the nest. There was no evidence that males could recognise their
own offspring within a brood and feed them preferentially. The number of offspring sired by each male was significantly correlated
with the number of days spent copulating with the attending female: on average, a male sired one offspring for every 2 days
of copulatory access. If males use their access to females to estimate paternity (and thereby decide on their subsequent level
of parental investment), a positive relationship is expected between the amount of female access and the subsequent feeding
rate to the nestlings. Nonetheless, male feeding effort was only weakly correlated with female access and more study is needed
to determine how males estimate their paternity in a brood.
Received: 1 June 1997 / Accepted after revision: 1 April 1998 相似文献
50.
Peter Weindler Frank Böhme Varis Liepa Wolfgang Wiltschko 《Behavioral ecology and sociobiology》1998,42(4):289-294
To assess the role of celestial rotation during daytime in the development of the magnetic compass course, pied flycatchers
(Ficedula hypoleuca Pallas, Muscicapidae) were handraised in Latvia under various celestial and magnetic conditions. Tests were performed during
autumn migration in the local geomagnetic field (50 000 nT, 73° inclination) in the absence of celestial cues. A group of
birds that had never seen the sky showed a bimodal preference for the migratory southwest-northeast axis, whereas a second
group that had been exposed to the natural sky from sunrise to sunset in the local geomagnetic field showed a unimodal preference
for the seasonally appropriate southwesterly direction. A third group that had also been exposed to the daytime sky, but in
the absence of magnetic compass information, also oriented bimodally along a southwest-northeast axis. These findings demonstrate
that observing celestial rotation during daytime enables birds to choose the right end of the migratory axis for autumn migration
at the Latvian test location. This transformation of axial behavior into appropriate migratory orientation, however, requires
the birds to have simultaneous access to information on both celestial rotation and the geomagnetic field.
Received: 19 September 1997 / Accepted after revision: 22 November 1997 相似文献