Describing mate preference functions and other function-valued traits.

Mate preferences are important causes of sexual selection. They shape the evolution of sexual ornaments and displays, sometimes maintaining genetic diversity and sometimes promoting speciation. Mate preferences can be challenging to study because they are expressed in animal brains and because they are a function of the features of potential mates that are encountered. Describing them requires taking this into account. We present a method for describing and analysing mate preference functions, and introduce a freely available computer program that implements the method. We give an overview of how the program works, and we discuss how it can be used to visualize and quantitatively analyse preference functions. In addition, we provide an informal review of different methods of testing mate preferences, with recommendations for how best to set up experiments on mate preferences. Although the program was written with mate preferences in mind, it can be used to study any function-valued trait, and we hope researchers will take advantage of it across a broad range of traits.

Ordinary least squares regression is indicated for studies of allometry.

When it comes to fitting simple allometric slopes through measurement data, evolutionary biologists have been torn between regression methods. On the one hand, there is the ordinary least squares (OLS) regression, which is commonly used across many disciplines of biology to fit lines through data, but which has a reputation for underestimating slopes when measurement error is present. On the other hand, there is the reduced major axis (RMA) regression, which is often recommended as a substitute for OLS regression in studies of allometry, but which has several weaknesses of its own. Here, we review statistical theory as it applies to evolutionary biology and studies of allometry. We point out that the concerns that arise from measurement error for OLS regression are small and straightforward to deal with, whereas RMA has several key properties that make it unfit for use in the field of allometry. The recommended approach for researchers interested in allometry is to use OLS regression on measurements taken with low (but realistically achievable) measurement error. If measurement error is unavoidable and relatively large, it is preferable to correct for slope attenuation rather than to turn to RMA regression, or to take the expected amount of attenuation into account when interpreting the data.

Curves as traits: genetic and environmental variation in mate preference functions.

Study of the genetic and developmental architecture of mate preferences lags behind the study of sexual ornaments. This is in part because of the challenges involved in describing mate preferences, which are expressed as a function of variation in ornaments. We used the function-valued approach to test for genetic and environmental components of variation in female mate preferences in Enchenopa treehoppers (Hemiptera: Membracidae). These insects communicate with plant-borne vibrational signals, and offer a case study of speciation involving sexual selection and environmental change. We focused on female preferences for male signal frequency, the most divergent signal trait in Enchenopa. Obtaining complete, individual-level descriptions of mate preferences in a full-sib, split-family rearing experiment, we document substantial genetic variation in mate preference functions. Focusing on traits describing variation in the shape of the preference functions, we further document considerable broad-sense heritability and evidence of weak genotype × environment interaction in most traits. Against the background of recent and rapid divergence in Enchenopa, these results indicate potent mechanisms that maintain variation and sustain the involvement of mate preferences in sexual selection.

Observation of a narrow charm-strange meson D(+)(sJ)(2632)-->D(+)(s)eta and D(0)K(+).

We report the first observation of a charm-strange meson D(+)(sJ)(2632) at a mass of 2632.5+/-1.7 MeV/c(2) in data from SELEX, the charm hadro-production experiment E781 at Fermilab. This state is seen in two decay modes, D(+)(s)eta and D0K+. In the D(+)(s)eta decay mode we observe a peak with 101 events over a combinatoric background of 54.9 events at a mass of 2635.4+/-3.3 MeV/c(2). There is a corresponding peak of 21 events over a background of 6.9 at 2631.5+/-2.0 MeV/c(2) in the decay mode D0K+. The decay width of this state is <17 MeV/c(2) at 90% confidence level. The relative branching ratio Gamma(D0K+)/Gamma(D(+)(s)eta) is 0.14+/-0.06. The mechanism that keeps this state narrow is unclear. Its decay pattern is also unusual, being dominated by the D(+)(s)eta decay mode.

First observation of the doubly charmed baryon Xi(+)(cc).

We observe a signal for the doubly charmed baryon Xi(+)(cc) in the charged decay mode Xi(+)(cc)-->Lambda(+)(c)K-pi(+) in data from SELEX, the charm hadroproduction experiment at Fermilab. We observe an excess of 15.9 events over an expected background of 6.1+/-0.5 events, a statistical significance of 6.3sigma. The observed mass of this state is 3519+/-1 MeV/c(2). The Gaussian mass width of this state is 3 MeV/c(2), consistent with resolution; its lifetime is less than 33 fs at 90% confidence.

Evaluating a brief alcohol intervention with fraternities.

OBJECTIVE: The current study tested the efficacy of a brief intervention designed to reduce drinking and drinking-related consequences among first-year fraternity members. METHOD: Twelve fraternities were randomly assigned to receive either a motivational enhancement intervention with individual and housewide feedback components (n = 6 houses) or a treatment-as-usual control condition (n = 6 houses). Individual feedback was delivered either by peer interviewers or professional research staff. Participants were assessed during their pledge (first) year of house membership and during a follow-up period 1 year later. RESULTS: Of the participants who completed follow-up (N = 120), fraternity members who received the brief intervention reported significant reductions in alcohol use (total average consumption) and typical peak blood alcohol concentrations when compared with fraternity members in the control condition. No differences in drinking-related consequences were observed. Fraternity members who received their individualized feedback from peer interviewers and professional members of the research staff reported similar outcomes. CONCLUSIONS: Results provide support for the efficacy of a brief motivational enhancement intervention in reducing drinking within this high-risk population. The cost-effective use of peer interviewers appears to be a promising strategy for delivering individualized prevention programming in college populations.

Precision measurements of the lambda(+)(c) and D0 lifetimes.

We report new precision measurements of the lifetimes of the Lambda(+)(c) and D0 from SELEX, the charm hadroproduction experiment at Fermilab. Based upon 1630 Lambda(+)(c) and 10 210 D0 decays we observe lifetimes of tau[Lambda(+)(c)] = 198.1+/-7.0+/-5.6 fs and tau[D0] = 407.9+/-6.0+/-4.3 fs.

Observation of the Cabibbo-Suppressed Decay Ξ_{c}

We report the first observation of the Cabibbo-suppressed charm baryon decay Ξ_{c}^{+}→pK^{-}π^{+}. We observe 150±22±5 events for the signal. The data were accumulated using the SELEX spectrometer during the 1996-1997 fixed target run at Fermilab, chiefly from a 600 GeV/c Σ^{-} beam. The branching fractions of the decay relative to the Cabibbo-favored Ξ_{c}^{+}→Σ^{+}K^{-}π^{+} and Ξ_{c}^{+}→Ξ^{-}π^{+}π^{+} are measured to be B(Ξ_{c}^{+}→pK^{-}π^{+})/B(Ξ_{c}^{+}→Σ^{+}K^{-}π^{+})=0.22±0.06±0.03 and B(Ξ_{c}^{+}→pK^{-}π^{+})/B(Ξ_{c}^{+}→Ξ^{-}π^{+}π^{+})=0.20±0.04±0.02, respectively.

Readiness to change alcohol drinking habits after traumatic brain injury.

OBJECTIVE: To describe how motivated are persons with recent traumatic brain injury (TBI) to change their alcohol drinking habits and what factors affect their motivation. DESIGN: Survey. SETTING: Acute inpatient rehabilitation program. PATIENTS: Subjects were 50 patients with recent TBI during inpatient rehabilitation. MAIN OUTCOME MEASURES: Readiness to Change (RTC) questionnaire, Michigan Alcoholism Screening Test (MAST), and alcohol use questions. RESULTS: Subjects were 36 years old; 86% were men. Eighty-four percent fell in the contemplation or action phases. Comparisons with a separate medical patient sample suggested that TBI may be associated with greater contemplation of change and greater readiness to take action to change alcohol use. Multivariate analyses indicated that within the TBI sample a positive history of alcoholism, alcohol involved in the accident, and higher daily consumption were associated with greater readiness to change (especially contemplation scores). CONCLUSIONS: Soon after TBI, drinkers frequently contemplate changing their alcohol use. This situation may represent an underutilized window of opportunity to reduce postinjury alcohol use and abuse. Motivational interviewing techniques seem well suited to facilitate change during this period.

Globin adducts of benzo[a]pyrene: markers of inhalation exposure as measured in F344/N rats.

We have explored methods for determining benzo[a]pyrene (BaP) dosimetry by measuring adduction levels to F344/N rat blood hemoglobin, and have refined and validated an assay that measures the in vivo binding of the 7,8-diol 9,10-epoxide metabolite of BaP to globin. The assay for BaP-globin adducts was based on the release of tetrahydroxy-BaP (BaP-tetrols) from globin by mild acid hydrolysis. After extensive isolation, BaP-tetrols were quantitated by high-pressure liquid chromatography using fluorescence detection. BaP-tetrol levels were measured in rats dosed intraperitoneally with 242, 71 and 24 mumol BaP kg-1 body weight in corn oil. The formation of BaP-tetrols was not linear with dose. The lowest dose yielded adduct levels that represented the limits of sensitivity for the method, as performed in this laboratory. Once this limit of sensitivity was established, the potential use of the assay was assessed by measuring the radiochemical binding of inhaled [14C]BaP or its metabolites to the globin of F344/N rats. Rats were exposed for 4 h per day, 1 day per week, for 12 weeks to pure aerosols of [14C]BaP at a level of 2 mg m-3. At the conclusion of exposure, rats were sacrificed and globin was isolated. The extent of [14C]BaP binding to the globin was determined by liquid scintillation spectrometry. Rats exposed to aerosols of [14C]BaP had statistically increased levels of binding to globin, and the levels were comparable to those observed previously after intragastric administration.(ABSTRACT TRUNCATED AT 250 WORDS)