Jumping in lantern bugs (Hemiptera, Fulgoridae).

Lantern bugs are amongst the largest of the jumping hemipteran bugs, with body lengths reaching 44 mm and masses reaching 0.7 g. They are up to 600 times heavier than smaller hemipterans that jump powerfully using catapult mechanisms to store energy. Does a similar mechanism also propel jumping in these much larger insects? The jumping performance of two species of lantern bugs (Hemiptera, Auchenorrhyncha, family Fulgoridae) from India and Malaysia was therefore analysed from high-speed videos. The kinematics showed that jumps were propelled by rapid and synchronous movements of both hind legs, with their trochantera moving first. The hind legs were 20-40% longer than the front legs, which was attributable to longer tibiae. It took 5-6 ms to accelerate to take-off velocities reaching 4.65 m s-1 in the best jumps by female Kalidasa lanata. During these jumps, adults experienced an acceleration of 77 g, required an energy expenditure of 4800 µJ and a power output of 900 mW, and exerted a force of 400 mN. The required power output of the thoracic jumping muscles was 21,000 W kg-1, 40 times greater than the maximum active contractile limit of muscle. Such a jumping performance therefore required a power amplification mechanism with energy storage in advance of the movement, as in their smaller relatives. These large lantern bugs are near isometrically scaled-up versions of their smaller relatives, still achieve comparable, if not higher, take-off velocities, and outperform other large jumping insects such as grasshoppers.

"I Don't Feel Like I Have a Problem Because I Can Still Go To Work and Function": Problem Recognition Among Persons With Substance Use Disorders.

Background: Persons with substance use disorders (SUDs) who do not recognize their substance use as problematic are less likely to perceive needing treatment and less motivated to seek help. Factors that contribute to problem recognition among persons with SUDs are poorly understood. Objective: To explore in-depth factors that may explain why those who meet diagnostic criteria for SUDs do not perceive having a substance abuse problem. Methods: We recruited 54 participants with recent (i.e., past-5-year) SUD for qualitative interviews. Participants were recruited via online ads and screened for eligibility through an online survey. Interview questions focused on participants' alcohol and drug use behaviors, adverse consequences stemming from their substance use, past treatment use experiences, and barriers/reasons for not using specialty treatment. Interviews were thematically coded to identify prominent themes that may explain low problem recognition. Results: We identified two prominent themes that contributed to problem recognition: modifying substance use behaviors to avoid adverse consequences and stigma (i.e., "othering"). Participants who (1) reported adjusting their alcohol and drug use in ways that would not interfere with important life responsibilities, especially work-responsibilities; (2) described those with alcohol and drug problems negatively; and (3) associated treatment with personal defeat were less likely to perceive having a SUD. Conclusions/Importance: These findings can be used to inform intervention strategies aimed at increasing problem recognition among persons with SUDs. Such strategies may facilitate motivation (i.e., desire for help and treatment readiness) to use and complete treatment, thereby reducing the unmet treatment gap among persons with SUDs.

Exploring Jordan's rule in Pacific three-spined stickleback Gasterosteus aculeatus.

Coastal marine Gasterosteus aculeatus were captured from seven locations along the Pacific coast of North America, ranging across 21·8° latitude to test Jordan's rule, i.e. that vertebral number should increase with increasing latitude for related populations of fish. Vertebral number significantly increased with increasing latitude for both total and caudal vertebral number. Increasing length with latitude (sensu Bergmann's rule) was also supported, but the predictions for Jordan's rule held when controlling for standard length. Pleomerism was weakly evidenced. Gasterosteus aculeatus exhibited sexual dimorphism for Jordan's rule, with both sexes having more vertebrae at higher latitudes, but only males showing a positive association between latitude and the ratio of caudal to abdominal vertebrae. The number of dorsal- and anal-fin rays and basals increased with increasing latitude, while pectoral-fin ray number decreased. This study reinforces the association between phenotypic variation and environmental variation in marine populations of G. aculeatus.

Correction: Evidence for a surface gold hydride on a nanostructured gold catalyst.

Correction for 'Evidence for a surface gold hydride on a nanostructured gold catalyst' by I. P. Silverwood et al., Chem. Commun., 2016, 52, 533-536.

Evidence for a surface gold hydride on a nanostructured gold catalyst.

Inelastic neutron scattering shows formation of a surface Au-H species, of key importance for the study of catalytic mechanisms. Previous assignment of this feature in the infrared as a purely Ce(3+) transition is shown to be erroneous on reducing the catalyst using hydrogen and deuterium.

Genome-wide patterns of divergence during speciation: the lake whitefish case study.

The nature, size and distribution of the genomic regions underlying divergence and promoting reproductive isolation remain largely unknown. Here, we summarize ongoing efforts using young (12 000 yr BP) species pairs of lake whitefish (Coregonus clupeaformis) to expand our understanding of the initial genomic patterns of divergence observed during speciation. Our results confirmed the predictions that: (i) on average, phenotypic quantitative trait loci (pQTL) show higher F(ST) values and are more likely to be outliers (and therefore candidates for being targets of divergent selection) than non-pQTL markers; (ii) large islands of divergence rather than small independent regions under selection characterize the early stages of adaptive divergence of lake whitefish; and (iii) there is a general trend towards an increase in terms of numbers and size of genomic regions of divergence from the least (East L.) to the most differentiated species pair (Cliff L.). This is consistent with previous estimates of reproductive isolation between these species pairs being driven by the same selective forces responsible for environment specialization. Altogether, dwarf and normal whitefish species pairs represent a continuum of both morphological and genomic differentiation contributing to ecological speciation. Admittedly, much progress is still required to more finely map and circumscribe genomic islands of speciation. This will be achieved through the use of next generation sequencing data but also through a better quantification of phenotypic traits moulded by selection as organisms adapt to new environmental conditions.

Frozen F1's amidst a masterpiece of nature: new insights into the rare hybrid origin of gynogenesis in the Amazon molly (Poecilia formosa).

All-female 'species' of fish have been shown to be great models in ecological and evolutionary studies because of the insights they can provide into the origin and evolution of asexuality, the ecology of hybrids, associations between genotype and environment, and the maintenance of sex. Gynogenetic organisms that evolved from sexual ancestors, and combine the disadvantageous traits from sexuality and asexuality, have long baffled evolutionary biologists trying to understand their origin and persistence with their sympatric sexual counterparts. In this issue, a new study using an integrated molecular phylogenetic and classical genetic approach has uncovered compelling evidence regarding the obscure asexual origin of the Amazon molly, Poecilia formosa. By performing an extensive phylogeographic analysis, Stöck et al. (2010) provide evidence that the Amazon molly arose only once within its history, with monophyly being strongly supported by mitochondrial DNA and microsatellite analyses. This result, combined with an elaborate failed attempt to resynthesize the lineage, suggests that vertebrate gynogens such as the Amazon molly are not rare because they are at a disadvantage to their sexual counterparts, but because the genomic conditions under which they arise are rare. Organisms that apparently combine the disadvantages of both sexuality and asexuality remain difficult to understand from both an ecological and an evolutionary perspective, and Stöck et al. (2010) highlight several outstanding important questions. Nonetheless, given that we now have a better knowledge of the origin and history of this unique 'species', this should allow researchers to better understand how these frozen F1's can persist amidst the masterpiece of nature.

Pervasive sex-linked effects on transcription regulation as revealed by expression quantitative trait loci mapping in lake whitefish species pairs (Coregonus sp., Salmonidae).

Mapping of expression quantitative trait loci (eQTL) is a powerful means for elucidating the genetic architecture of gene regulation. Yet, eQTL mapping has not been applied toward investigating the regulation architecture of genes involved in the process of population divergence, ultimately leading to speciation events. Here, we conducted an eQTL mapping experiment to compare the genetic architecture of transcript regulation in adaptive traits, differentiating the recently evolved limnetic (dwarf) and benthic (normal) species pairs of lake whitefish. The eQTL were mapped in three data sets derived from an F(1) hybrid-dwarf backcrossed family: the entire set of 66 genotyped individuals and the two sexes treated separately. We identified strikingly more eQTL in the female data set (174), compared to both male (54) and combined (33) data sets. The majority of these genes were not differentially expressed between male and female progeny of the backcross family, thus providing evidence for a strong pleiotropic sex-linked effect in transcriptomic regulation. The subtelomeric region of a linkage group segregating in females encompassed >50% of all eQTL, which exhibited the most pronounced additive effects. We also conducted a direct comparison of transcriptomic profiles between pure dwarf and normal progeny reared in controlled conditions. We detected 34 differentially expressed transcripts associated with eQTL segregating only in sex-specific data sets and mostly belonging to functional groups that differentiate dwarf and normal whitefish in natural populations. Therefore, these eQTL are not related to interindividual variation, but instead to the adaptive and historical genetic divergence between dwarf and normal whitefish. This study exemplifies how the integration of genetic and transcriptomic data offers a strong means for dissecting the functional genomic response to selection by separating mapping family-specific effects from genetic factors under selection, potentially involved in the phenotypic divergence of natural populations.

Concordance of chlamydia trachomatis infections within sexual partnerships.

OBJECTIVES: The enhanced sensitivity of nucleic acid amplification tests (NAAT) provides an opportunity for estimating the prevalence of untreated Chlamydia trachomatis infections. The transmissibility and public health significance of some NAAT-identified infections are, however, not known. METHODS: Adults attending an urban emergency department provided specimens for C trachomatis screening using NAAT. Participants testing positive were offered follow-up including re-testing for C trachomatis using NAAT and traditional methods, eg culture and direct fluorescent antibody, and were treated. Partners were offered identical evaluation and treatment. Overall, 90 C trachomatis-positive participants had one or more sexual partners enrolled. RESULTS: Evidence of transmission, as defined by infection concordance between partnerships, was observed among 75% of partners of index cases testing positive by both NAAT and traditional assay but only 45% of partners of index cases testing positive by NAAT only (prevalence ratio 1.7, 95% CI 1.1 to 2.5). Among index participants returning for follow-up, 17% had no evidence of C trachomatis infection by NAAT or traditional assay (median follow-up three weeks). CONCLUSIONS: A substantial proportion of positive NAAT results for chlamydial infection may be of lower transmissibility and may not persist after a short follow-up. The long-term health effects of some positive NAAT are uncertain.

The genetic architecture of ecological speciation and the association with signatures of selection in natural lake whitefish (Coregonus sp. Salmonidae) species pairs.

Adaptive evolutionary change is contingent on variation and selection; thus, understanding adaptive divergence and ultimately speciation requires information on both the genetic basis of adaptive traits as well as an understanding of the role of divergent natural selection on those traits. The lake whitefish (Coregonus clupeaformis) consists of several sympatric "dwarf" (limnetic) and normal (benthic) species pairs that co-inhabit northern postglacial lakes. These young species pairs have evolved independently and display parallelism in life history, behavioral, and morphological divergence associated with the use of distinct trophic resources. We identified phenotype-environment associations and determined the genetic architecture and the role of selection modulating population genetic divergence in sympatric dwarf and normal lake whitefish. The genetic architecture of 9 adaptive traits was analyzed in 2 hybrid backcrosses individually phenotyped throughout their life history. Significant quantitative trait loci (QTL) were associated with swimming behavior (habitat selection and predator avoidance), growth rate, morphology (condition factor and gill rakers), and life history (onset of maturity and fecundity). Genome scans among 4 natural sympatric pairs, using loci segregating in the map, revealed a signature of selection for 24 loci. Loci exhibiting a signature of selection were associated with QTL relative to other regions of the genome more often than expected by chance alone. Two parallel QTL outliers for growth and condition factor exhibited segregation distortion in both mapping families, supporting the hypothesis that adaptive divergence contributing to parallel reductions of gene flow among natural populations may cause genetic incompatibilities. Overall, these findings offer evidence that the genetic architecture of ecological speciation is associated with signatures of selection in nature, providing strong support for the hypothesis that divergent natural selection is currently maintaining adaptive differentiation and promoting ecological speciation in lake whitefish species pairs.

Linkage maps of the dwarf and Normal lake whitefish (Coregonus clupeaformis) species complex and their hybrids reveal the genetic architecture of population divergence.

Elucidating the genetic architecture of population divergence may reveal the evolution of reproductive barriers and the genomic regions implicated in the process. We assembled genetic linkage maps for the dwarf and Normal lake whitefish species complex and their hybrids. A total of 877 AFLP loci and 30 microsatellites were positioned. The homology of mapped loci between families supported the existence of 34 linkage groups (of 40n expected) exhibiting 83% colinearity among linked loci between these two families. Classes of AFLP markers were not randomly distributed among linkage groups. Both AFLP and microsatellites exhibited deviations from Mendelian expectations, with 30.4% exhibiting significant segregation distortion across 28 linkage groups of the four linkage maps in both families (P < 0.00001). Eight loci distributed over seven homologous linkage groups were significantly distorted in both families and the level of distortion, when comparing homologous loci of the same phase between families, was correlated (Spearman R = 0.378, P = 0.0021). These results suggest that substantial divergence incurred during allopatric glacial separation and subsequent sympatric ecological specialization has resulted in several genomic regions that are no longer complementary between dwarf and Normal populations issued from different evolutionary glacial lineages.

The genetic basis of intrinsic and extrinsic post-zygotic reproductive isolation jointly promoting speciation in the lake whitefish species complex (Coregonus clupeaformis).

Understanding the genetic architecture of reproductive barriers and the evolutionary forces that drove their divergence represents a considerable challenge towards understanding speciation. The objective of this study was to determine the genetic basis of intrinsic and extrinsic post-zygotic isolation in diverging populations of dwarf and normal lake whitefish with allopatric glacial origins. We found that the rate of embryonic mortality was 5.3-6.5 times higher in dwarf-normal hybrid backcrosses during development than in F1 dwarf and normal crosses. When comparing embryos that died during development against larvae that successfully hatched, patterns of Mendelian segregation at 101 loci whose linkage is known identified 13 loci distributed over seven linkage groups that exhibited significant shifts in segregation ratios leading to significant segregation distortion at these loci in the surviving progeny. Controlled crosses and quantitative trait loci analysis revealed a significant genetic basis for developmental time until emergence, a trait critical to fish larval survival in nature. Hatching backcross progeny exhibited asynchronous emergence and transgressive segregation, suggesting that extrinsic post-zygotic isolation may select against hybridization in specific environmental contexts. Evidence of a genetic basis for increased embryonic mortality followed by asynchronous emergence indicated that intrinsic and extrinsic mechanisms are not mutually exclusive in the formation and maintenance of reproductive isolation, but may be jointly promoting population divergence and ultimately speciation.

Audio computer assisted interviewing to measure HIV risk behaviours in a clinic population.

OBJECTIVES: To examine whether audio computer assisted survey interviewing (ACASI) influenced responses to sensitive HIV risk behaviour questions, relative to interviewer administration of those questions (IAQ), among patients attending a sexually transmitted infection (STI) clinic and whether the impact of interview mode on reporting of risk behaviours was homogeneous across subgroups of patients (defined by age, sex, and previous STI clinic experience). METHODS: 1350 clinic patients were assigned to complete a detailed behavioural survey on sexual risk practices, previous STIs and symptoms, condom use, and drug and alcohol use using either ACASI or IAQ. RESULTS: Respondents assigned to ACASI were more likely to report recent risk behaviours such as sex without a condom in the past 24 hours (adjusted OR = 1.9), anal sex (adjusted OR = 2.0), and one or more new partners in the past 6 months (adjusted OR = 1.5) compared to those interviewed by IAQ. The impact of ACASI varied by sex but, contrary to expectations, not by whether the patient had previously visited an STI clinic. Mode of survey administration made little difference within this population in reports of STI knowledge, previous STIs, STI symptoms, or illicit drug use. CONCLUSION: ACASI provides a useful tool for improving the quality of behavioural data in clinical environments.

Monitoring STI prevalence using telephone surveys and mailed urine specimens: a pilot test.

OBJECTIVES: This pilot test assessed the feasibility of a cost effective population based approach to STI monitoring using automated telephone interviews, urine specimen collection kits sent out and returned by US Postal Service mail, and monetary incentives to motivate participation. METHODS: 100 residents of Baltimore, MD, USA, completed an automated telephone survey and agreed to mail in a urine specimen to be tested for chlamydia and gonorrhoea. Participants were paid dollar 10 for completing the survey and dollar 40 for mailing the specimen. RESULTS: 86% of survey participants mailed in a urine specimen for testing. CONCLUSIONS: Automated telephone surveys linked with testing of mailed-in urine specimens may be a feasible lower cost (relative to household surveys) method of estimating infection prevalences in a population.

Integrating QTL mapping and genome scans towards the characterization of candidate loci under parallel selection in the lake whitefish (Coregonus clupeaformis).

As natural selection must act on underlying genetic variation, discovering the number and location of loci under the influence of selection is imperative towards understanding adaptive divergence in evolving populations. Studies employing genome scans have hypothesized that the action of divergent selection should reduce gene flow at the genomic locations implicated in adaptation and speciation among natural populations, yet once 'outlier' patterns of variation have been identified the function and role of such loci needs to be confirmed. We integrated adaptive QTL mapping and genomic scans among diverging sympatric pairs of the lake whitefish (Coregonus clupeaformis) species complex in order to test the hypothesis that differentiation between dwarf and normal ecotypes at growth-associated QTL was maintained by directional selection. We found evidence of significantly high levels of molecular divergence among eight growth QTL where two of the strongest candidate loci under the influence of directional selection exhibited parallel reductions of gene flow over multiple populations.

LCR testing for gonorrhoea and chlamydia in population surveys and other screenings of low prevalence populations: coping with decreased positive predictive value.

OBJECTIVE: Nucleic acid amplification tests have facilitated field based STD studies and increased screening activities. However, even with highly specific tests, the positive predictive value (PPV) of such tests may be lower than desirable in low prevalence populations. We estimated PPVs for a single LCR test in a population survey in which positive specimens were retested. METHODS: The Baltimore STD and Behavior Survey (BSBS) was a population based behavioural survey of adults which included collecting urine specimens to assess the prevalence of gonorrhoea and chlamydial infection. Gonorrhoea and chlamydial infection were diagnosed by ligase chain reaction (LCR). Nearly all positive results were retested by LCR. Because of cost considerations, negative results were not confirmed. Predicted curves for the PPV were calculated for a single testing assuming an LCR test sensitivity of 95%, and test specificities in the range 95.0%-99.9%, for disease prevalences between 1% and 10%. Positive specimens were retested to derive empirical estimates of the PPV of a positive result on a single LCR test. RESULTS: 579 participants age 18-35 provided urine specimens. 20 (3.5%) subjects initially tested positive for chlamydial infection, and 39 (6.7%) tested positive for gonococcal infection. If positive results on the repeat LCR are taken as confirmation of a "true" infection, the observed PPV for the first LCR testing was 89.5% for chlamydial infection and 83.3% for gonorrhoea. This is within the range of theoretical PPVs calculated from the assumed sensitivities and specificities of the LCR assays. CONCLUSIONS: Empirical performance of a single LCR testing approximated the theoretically predicted PPV in this field study. This result demonstrates the need to take account of the lower PPVs obtained when such tests are used in field studies or clinical screening of low prevalence populations. Repeat testing of specimens, preferably with a different assay (for example, polymerase chain reaction), and disclosure of the non-trivial potential for false positive test results would seem appropriate in all such studies.

Combining the analyses of introgressive hybridisation and linkage mapping to investigate the genetic architecture of population divergence in the lake whitefish (Coregonus clupeaformis, Mitchill).

Adaptation and reproductive isolation, the engines of biological diversity, are still elusive when discussing the genetic bases of speciation. Namely, the number of genes and magnitude of selection acting positively or negatively on genomic traits implicated in speciation is contentious. Here, we describe the first steps of an ongoing research program aimed at understanding the genetic bases of population divergence and reproductive isolation in the lake whitefish (Coregonus clupeaformis). A preliminary linkage map originating from a hybrid cross between dwarf and normal ecotypes is presented, whereby some of the segregating AFLP markers were found to be conserved among natural populations. Maximum-likelihood was used to estimate hybrid indices from non-diagnostic markers at 998 AFLP loci. This allowed identification of the most likely candidate loci that have been under the influence of selection during the natural hybridisation of whitefish originating from different glacial races. As some of these loci could be identified on the linkage map, the possibility that selection of traits in natural populations may eventually be correlated to specific chromosomal regions was demonstrated. The future prospects and potential of these approaches to elucidate the genetic bases of adaptation and reproductive isolation among sympatric ecotypes of lake whitefish is discussed.

Parallel somatotopic maps of gustatory and mechanosensory neurons in the central nervous system of an insect.

Relatively little is still known about the sense of taste, or contact chemoreception, compared with other sensory modalities, despite its importance to many aspects of animal behaviour. The central projections of the sensory neurons from bimodal contact chemoreceptors (basiconic sensilla) were compared with those from mechanosensory tactile hairs located on similar regions of the middle leg of the locust. Basiconic sensilla are multiply innervated, containing one mechanosensory and several chemosensory neurons, whereas tactile hairs are innervated by a single mechanosensory neuron. We show that the sensory neurons from tactile hairs form a complete 3-dimensional somatotopic map in the mesothoracic ganglion. Sensory neurons from hairs located on the coxa projected to a region near the midline of the ganglion with neurons from hairs located on progressively more distal parts of the leg arborizing in successively more lateral regions of neuropil. All the neurons from basiconic sensilla, both mechanosensory and chemosensory, also projected in a similar, strictly somatotopic, manner, and the arbors from these neurons overlapped considerably with those from tactile hairs on equivalent parts of the leg to form a continuous region. Thus, the position of a receptor on the leg is preserved in the central nervous system not only for the mechanosensory neurons from both tactile hairs and basiconic sensilla but also for chemosensory neurons. We could observe no anatomical features or small differences in projection region between sensory neurons from individual basiconic sensilla consistent with differences in modality.

Local movements evoked by chemical stimulation of the hind leg in the locust Schistocerca gregaria.

The behavioural responses of desert locusts, Schistocerca gregaria, to solutions of four behaviourally relevant chemicals (sodium chloride, sucrose, nicotine hydrogen tartrate and lysine glutamate) applied as droplets to the hind tarsus were analysed. All responses following within 1 s of chemical stimulation were local leg avoidance reflexes, and the probability of eliciting such a response increased in a dose-dependent manner with increasing concentration for all the chemicals tested. Chemical identity, however, critically determined the concentration threshold at which the different chemicals became an effective stimulus. For example, a 2.5 mmol l(-)(1) concentration of the secondary plant metabolite nicotine hydrogen tartrate (NHT), a potent feeding deterrent to locusts, was sufficient to evoke avoidance responses in 50 % of cases, whilst for the nutrients, sucrose and lysine glutamate, 250-500 mmol l(-)(1) of the chemical was needed to induce avoidance behaviour in 50 % of the locusts. NaCl was of intermediate effectiveness, with a 50 % response rate occurring at a concentration of approximately 50 mmol l(-)(1). The latency to the start of the response following stimulation was negatively correlated with the concentration of NaCl, but for the other chemicals concentration had no effect on latency. The duration of the avoidance behaviour decreased with increasing concentration for NaCl and more weakly for NHT, but not for the other chemicals. Adding a subthreshold concentration of sucrose to 50 mmol l(-)(1) NaCl decreased the incidence of response compared with 50 mmol l(-)(1) NaCl on its own. Experiments with other mixtures combining NaCl, sucrose and NHT indicate that the frequency and dynamics of the responses to chemical mixtures cannot be simply predicted from the responses to their individual constituents.

Correlates of sexually transmitted bacterial infections among U.S. women in 1995.

CONTEXT: Sexually transmitted diseases (STDs) of bacterial origin such as gonorrhea and chlamydial infection can lead to pelvic inflammatory disease (PID) and infertility. Identifying behaviors and characteristics associated with infection may assist in preventing these often asymptomatic diseases and their sequelae. METHODS: Data from 9,882 sexually active women who participated in the 1995 National Survey of Family Growth describe the characteristics of women who report a history of infection with a bacterial STD or of treatment for PID. Multivariate analysis is used to determine which demographic characteristics and sexual and health-related behaviors affect the likelihood of infection or the occurrence of complications. RESULTS: Overall, 6% of sexually active women reported a history of a bacterial STD, and 8% reported a history of PID. Women who first had sexual intercourse before age 15 were nearly four times as likely to report a bacterial STD, and more than twice as likely to report PID, as were women who first had sex after age 18. Having more than five lifetime sexual partners also was associated with both having an STD and having PID. PID was more common among women reporting a history of a bacterial STD (23%) than among women who reported no such history (7%). In multivariate analyses, age, race, age at first intercourse and lifetime number of sexual partners had a significant effect on the risk of a bacterial STD. Education, age, a history of IUD use, douching and a history of a bacterial STD had a significant impact on the risk of PID, but early onset of intercourse did not, and lifetime number of partners had only a marginal effect. CONCLUSIONS: The pattern of characteristics and behaviors that place women at risk of infection with bacterial STDs is not uniform among groups of women. Further, the level of self-reported PID would suggest higher rates of gonorrhea and chlamydial infection than reported.