A new condensed toluene mechanism for Carbon Bond: CB05-TU

Toluene is ubiquitous in urban atmospheres and is a precursor to tropospheric ozone and aerosol (smog). An important characteristic of toluene chemistry is the tendency of some degradation products (e.g., cresols and methyl-catechols) to form organic nitro and nitrate compounds that sequester NOx (NO and NO₂) from active participation in smog formation. Explaining the NOx sinks in toluene degradation has made mechanism development more difficult for toluene than for many other organic compounds. Another challenge for toluene is explaining sources of radicals early in the degradation process. This paper describes the development of a new condensed toluene mechanism consisting of 26 reactions, and evaluates the performance of CB05 with this new toluene scheme (Toluene Update, TU) against 38 chamber experiments at 7 different environmental chambers, and provides recommendations for future developments. CB05 with the current toluene mechanism (CB05-Base) under-predicted the maximum O₃ and O₃ production rate for many of these toluene–NOx chamber experiments, especially under low-NOx conditions ([NOx]_t=0 < 100 ppb). CB05 with the new toluene mechanism (CB05-TU) includes changes to the yields and reactions of cresols and ring-opening products, and showed better performance than CB05-Base in predicting the maximum O₃, O₃ formation rate, NOx removal rate and cresol concentration. Additional environmental chamber simulations with xylene–NOx experiments showed that the TU mechanism updates tended to improve mechanism performance for xylene.     

The ozone productivity of n-propyl bromide: Part 2--An exception to the Maximum Incremental Reactivity Scale

In an earlier paper the ozone-forming potential of n-propyl bromide (NPB) was studied with a new methodology designed to address issues associated with a marginal smog-forming compound. However, the U.S. Environmental Protection Agency (EPA) subsequently revised its policy and now recommends using the Maximum Incremental Reactivity (MIR) scale to rank the ozone-forming potential of all volatile organic compounds (VOCs), including those of marginal ozone productivity. Nevertheless, EPA contemplated exceptions to the box-model-derived MIR scale by allowing use of photochemical grid-model simulations for case specific reactivity assessments. The California Air Resources Board (CARB) also uses the MIR scale and CARB has a Reactivity Scientific Advisory Committee that can consider exceptions to the MIR scale. In this study, grid-model simulations that were recommended by EPA are used to evaluate the incremental ozone impacts of NPB using an update to the chemical mechanism developed in an earlier paper. New methods of analysis of the grid-model output are further developed here to quantify the relative reactivities between NPB and ethane over a wide range of conditions. The new grid-model-based analyses show that NPB is significantly different and generally less in ozone-forming potential (i.e., reactivity) than predicted by the box-model-based MIR scale relative to ethane, EPA's "bright-line" test for non-VOC status. Although NPB has low reactivity compared to typical VOCs on any scale, the new grid-model analyses developed here show that NPB is far less reactive (and even has negative reactivity) compared to the reactivity predicted by the MIR scale.     

Interactions in male baboons: the importance of both males’ testosterone

To date, research on testosterone and behavior has focused on individuals, even when studying social behaviors that necessarily involve multiple participants. Here, we explore male responses to other males of different dominance ranks and testosterone levels in a population of wild baboons. In chacma baboons (Papio hamadryas ursinus) of the Okavango Delta, a male’s testosterone is related to his rank trajectory and, therefore, the threat he poses to other males. To examine the effects of testosterone and rank on male–male interactions, we used playback experiments to measure how a target male responded to the simulated approach of another male, scoring responses by whether or not the subject moved away from the speaker in the first minute. High testosterone subjects did not move away from the speaker more often than low testosterone subjects, but high testosterone callers elicited a move more often than low testosterone callers. When the combined testosterone of the subject and caller was high, moves were most common. The rank relationship between subject and caller did not predict moves, but the effect of combined testosterone on moving was most pronounced in adjacently ranked males. Adjacently ranked, high testosterone males are the most likely to be competing for each others’ rank, and our experiments on these dyads elicited the most moves. Both behavioral and experimental observations indicate that testosterone may be more important than the rank relationship in predicting the outcome of male–male interactions. Furthermore, combined information on the testosterone of both males was the best predictor of results, highlighting the utility of dyadic analyses when relating testosterone to behavior.     

Birth season testosterone levels in male Verreaux’s sifaka, Propithecus verreauxi: insights into socio-demographic factors mediating seasonal testicular function

Previous research suggests that although reproduction and testicular function in wild sifaka (Propithecus verreauxi) are highly seasonal, birth season elevations in fecal testosterone (T) in transferring males indicate that social factors may be as important as climatic factors in regulating reproductive function in sifaka. This paper examines the relationship of male dispersal and social status to the patterning of birth season aggression and testicular function in P. verreauxi at Beza Mahafaly Special Reserve, Madagascar. Behavioral and hormonal data were collected from a total of 38 adult males, 15 residing in seven stable groups and 23 living in eight unstable groups, yielding 186 fecal samples and 493 focal animal hours of observation. The results suggest that birth season elevations in fecal testosterone are the consequence of social disruption resulting from male movements between groups and the particular responses of individual males to dispersal events. Hormonal responses to dispersal events appear to precede behavioral responses and occasionally register reactions not concomitantly evident in the behavioral response, and may be predictive of future events. Hormonal reactions occurred primarily in resident alpha males, suggesting that they differ in their assessment of destabilizing influences, perhaps due to different reproductive opportunities and/or investment. These findings are important for the new insights they provide into the role of androgens in mediating male dispersal, life history, and reproductive strategies, and suggest that investigations of androgen-behavior interactions in free-ranging populations can be a powerful new tool for assessing the contextual and motivational basis of social behavior. Received: 22 November 1999 / Revised: 27 April 2000 / Accepted: 15 October 2000     

Pathophysiology,diagnosis and management of prenatal upper tract dilatation

Upper tract dilatation presenting as renal pelvis dilatation with or without ureteric dilatation is one of the more common abnormalities detected on prenatal ultrasound scanning. The majority of cases are due to pelvi-ureteric and vesico-ureteric junction anomalies, and vesico-ureteric reflux. Prenatal diagnosis with ultrasound may be aided by biochemical analysis of fetal blood and urine. The natural history of prenatally detected abnormalities remains under review. Precise diagnosis, and therefore prognosis, may not be made until after birth. Copyright © 2001 John Wiley & Sons, Ltd.     

Duplex systems

Duplex kidneys occur in 0.8% of the general population, many of whom are asymptomatic. Children with duplex kidneys may be prone to urinary tract infections because of vesico-ureteric reflux or obstruction. Surgical management is usually required once symptoms occur. Increasing numbers of duplex kidneys are now prenatally diagnosed by ultrasound, resulting in the development of early postnatal strategies to try and reduce morbidity. Copyright © 2001 John Wiley & Sons, Ltd.     

Variation among congeneric dinoflagellates from the northeastern United States and Canada

Relationships among dinoflagellates of the genus Alexandrium (=Protogonyaulax) from Long Island, New England, USA, and northeastern Canada were investigated between 1983 and 1987 using enzyme electrophoresis. A relative lack of heterogeneity among toxic isolates was observed despite large geographic separations of source populations. This observation is in marked contrast to observations on toxic members of this genus from the west coast of Canada and the United States. These different enzyme variability patterns support the proposal that dispersal of toxic strains in the east from a common source has occurred recently, presumably from established populations in northern Maine, USA, or Canada. Non-toxic strains from the study area were only distantly related to toxic isolates, consistent with their different morphology and separate species designations. One non-toxic isolate from a different region, that is conspecific with a number of the toxic strains, was more similar to these isolates than to other non-toxic clones.     

Size of sexual swellings reflects ovarian function in chimpanzees (<Emphasis Type="Italic">Pan troglodytes</Emphasis>)

While many theories exist on the evolution of the sexual swelling signal in female primates, the significance of the very large and variable swellings found in some catarrhine primates is still debated. As suggested by Pagel [(1994) Anim Behav 47:1333–1341], these exaggerated and costly signals have the potential to provide information about differential female reproductive quality to males. While Domb [(2000) Department of Anthropology, Harvard University, Cambridge] and Domb and Pagel [(2001) Nature 410:204–206] propose that swellings serve to reliably indicate between-female fitness differences, we hypothesize that they may indicate current reproductive cycle quality, within or between females. This study examines the between-cycle relationship between ovarian function, gauged via fecal steroid analysis, and absolute size of sexual swellings, yielded through photogrammetric methods. Fourteen cycles from eight captive, group-living chimpanzees (Pan troglodytes) exhibited considerable variability both in ovarian steroid levels and maximum sexual swelling size. Nearly all measures of a female's maximal swelling in a cycle correlated with early follicular and early luteal estradiol averages and the duration of luteal progesterone elevation. Swelling area was also correlated with late follicular estradiol. Given past evidence that such measures of ovarian function predict conceptive success, these data strongly suggest that swellings could convey information to competing males about the fecundability of a potential mate.Communicated by C. Nunn     

Testosterone predicts future dominance rank and mating activity among male chacma baboons

Despite the many benefits that testosterone has on male reproduction, sustaining high levels of testosterone for long periods can be costly. The challenge hypothesis predicts that males will show temporarily sustained elevations of testosterone at critical periods, counterbalanced by decreased levels during noncritical periods. We investigated male testosterone measures extracted from fecal samples in a group of chacma baboons (Papio hamadryas ursinus) living in the Okavango Delta, Botswana. Because rank serves as a proxy for competition for mates, we examined how male testosterone was related to dominance rank, age, aggression, and mating activity. Males showed an elevation in testosterone at maturity; young adult males had the highest testosterone levels followed by a steady decline with age. Among dispersing males, testosterone was temporarily elevated in the month following dispersal. After controlling for age, testosterone and rank were unrelated, but testosterone and changes in rank were positively correlated, such that males rising in rank had higher testosterone than males falling in rank. Thus, for males in this group, testosterone was predictive of a male's rank trajectory, or future rank. Similarly, male testosterone levels predicted future, rather than current, mating activity. Finally, male testosterone and aggression rates were unrelated during stable periods in the dominance hierarchy but positively related during unstable periods when high ranks were being contested. In general, our results support the challenge hypothesis with males exhibiting elevated testosterone in association with the acquisition of high rank (ensuring access to mates), rather than with mating itself.