Geographic body size variation in the periodical cicadas Magicicada: implications for life cycle divergence and local adaptation.

Seven species in three species groups (Decim, Cassini and Decula) of periodical cicadas (Magicicada) occupy a wide latitudinal range in the eastern United States. To clarify how adult body size, a key trait affecting fitness, varies geographically with climate conditions and life cycle, we analysed the relationships of population mean head width to geographic variables (latitude, longitude, altitude), habitat annual mean temperature (AMT), life cycle and species differences. Within species, body size was larger in females than males and decreased with increasing latitude (and decreasing habitat AMT), following the converse Bergmann's rule. For the pair of recently diverged 13- and 17-year species in each group, 13-year cicadas were equal in size or slightly smaller on average than their 17-year counterparts despite their shorter developmental time. This fact suggests that, under the same climatic conditions, 17-year cicadas have lowered growth rates compared to their 13-years counterparts, allowing 13-year cicadas with faster growth rates to achieve body sizes equivalent to those of their 17-year counterparts at the same locations. However, in the Decim group, which includes two 13-year species, the more southerly, anciently diverged 13-year species (Magicicada tredecim) was characterized by a larger body size than the other, more northerly 13- and 17-year species, suggesting that local adaptation in warmer habitats may ultimately lead to evolution of larger body sizes. Our results demonstrate how geographic clines in body size may be maintained in sister species possessing different life cycles.

Assessing lumbar paraspinal muscle cross-sectional area and fat composition with T1 versus T2-weighted magnetic resonance imaging: Reliability and concurrent validity.

PURPOSE: Studies using magnetic resonance imaging to assess lumbar multifidus cross-sectional area frequently utilize T1 or T2-weighted sequences, but seldom provide the rationale for their sequence choice. However, technical considerations between their acquisition protocols could impact on the ability to assess lumbar multifidus anatomy or its fat/muscle distinction. Our objectives were to examine the concurrent validity of lumbar multifidus morphology measures of T2 compared to T1-weighted sequences, and to assess the reliability of repeated lumbar multifidus measures. METHODS: The lumbar multifidus total cross-sectional area of 45 patients was measured bilaterally at L4 and L5, with histogram analysis determining the muscle/fat threshold values per muscle. Images were later re-randomized and re-assessed for intra-rater reliability. Matched images were visually rated for consistency of outlining between both image sequences. Bland-Altman bias, limits of agreement, and plots were calculated for differences in total cross-sectional area and percentage fat between and within sequences, and intra-rater reliability analysed. RESULTS: T1-weighted total cross-sectional area measures were systematically larger than T2 (0.2 cm2), with limits of agreement <±10% at both spinal levels. For percentage fat, no systematic bias occurred, but limits of agreement approached ±15%. Visually, muscle outlining was consistent between sequences, with substantial mismatches occurring in <5% of cases. Intra-rater reliability was excellent (ICC: 0.981-0.998); with bias and limits of agreement less than 1% and ±5%, respectively. CONCLUSION: Total cross-sectional area measures and outlining of muscle boundaries were consistent between sequences, and intra-rater reliability for total cross-sectional area and percentage fat was high indicating that either MRI sequence could be used interchangeably for this purpose. However, further studies comparing the accuracy of various methods for distinguishing fat from muscle are recommended.

Reproductive character displacement and speciation in periodical cicadas, with description of new species, 13-year Magicicada neotredecem.

Acoustic mate-attracting signals of related sympatric, synchronic species are always distinguishable, but those of related allopatric species sometimes are not, thus suggesting that such signals may evolve to "reinforce" premating species isolation when similar species become sympatric. This hypothesis predicts divergences restricted to regions of sympatry in partially overlapping species, but such "reproductive character displacement" has rarely been confirmed. We report such a case in the acoustic signals of a previously unrecognized 13-year periodical cicada species, Magicicada neotredecim, described here as a new species (see Appendix). Where M. neotredecim overlaps M. tredecim in the central United States, the dominant male call pitch (frequency) of M. neotredecim increases from approximately 1.4 kHz to 1.7 kHz, whereas that of M. tredecim remains comparatively stable. The average preferences of female M. neotredecim for call pitch show a similar geographic pattern, changing with the call pitch of conspecific males. Magicicada neotredecim differs from 13-year M. tredecim in abdomen coloration, mitochondrial DNA, and call pitch, but is not consistently distinguishable from 17-year M. septendecim; thus, like other Magicicada species, M. neotredecim appears most closely related to a geographically adjacent counterpart with the alternative life cycle. Speciation in Magicicada may be facilitated by life-cycle changes that create temporal isolation, and reinforcement could play a role by fostering divergence in premating signals prior to speciation. We present two theories of Magicicada speciation by life-cycle evolution: "nurse-brood facilitation" and "life-cycle canalization."

Heterozygous beta-thalassemia in pregnancy.

Present and past reproductive performance and various hematologic parameters were studied among 29 women with heterozygous beta-thalassemia. The pregnancy outcome and complications did not differ from those in the general population. Antepartum anemia and a distinctly lowered mean corpuscular volume were present almost universally.

Hematologic problems in pregnancy V. Obstetric transfusion therapy.

A study of 37,186 admissions, from 1970 through 1974, to a large southern charity hospital obstetrics service revealed a striking 63 per cent reduction in number of patients receiving blood transfusions. Analysis showed no change in patient population, bleeding disorders, toxemia, incidence of obstetric hemorrhage, serious febrile morbidity, or incidence of antepartum anemia. In the study period cesarean section rate increased 77 per cent and anemia at delivery markedly decreased. Transfusions associated with spontaneous abortion decreased by 70 per cent, and after the third study year no patient undergoing legal abortion received blood. The study demonstrated improvement in specific hematinic therapy of antepartum anemia and avoidance of transfusion therapy in the presence of uncharacterized antepartum or puerperal anemia. Despite the remarkable decrease in blood transfusions, obstetric outcome (including perinatal mortality rate, maternal mortality rate, and serious febrile morbidity) did not suffer but, indeed, improved.

Automated identification of episodes of asthma exacerbation for quality measurement in a computer-based medical record.

Harvard Community Health Plan and the Center for Intelligent Information Retrieval are developing tools to support automated quality fo care measurement from clinical text data. A statistically based text classification system uses semantic features in computerized encounter notes to identify acute exacerbations of asthma. Individual encounter notes are sorted in bins of highly likely, highly unlikely and uncertain likelihood of documenting exacerbation, and then aggregated into episodes of exacerbation for frequency analysis. It is estimated that this approach could reduce the burden of manual chart review by 65%.

Posterior disk displacement: morphologic assessment and measurement reliability-lumbar spine.

BACKGROUND: Magnetic resonance imaging is often used to assess for disk displacement after manipulation, but limited information about the true incidence of iatrogenic herniations exists. To design a study that evaluates for a causal relationship, preliminary data must be obtained relating to the size of different types of disk displacement. The reliability of chiropractic radiologists in assessing disks and a comparison of different measuring devices should also be evaluated. OBJECTIVE: To identify average measurements for normal and displaced disks and to assess the reliability of measurements by chiropractic radiologists. STUDY DESIGN: Intraobserver and interobserver reliability study assessing disk displacement on magnetic resonance scans. METHODS: Three evaluators assessed the disks on 122 magnetic resonance scans from two imaging centers. Six categories were graded, and digitizer and ruler measurements were compared. Forty-four scans were reassessed for intraobserver agreement. Intraobserver and interobserver variations were measured with intraclass correlation coefficient and kappa statistical analysis. Measurement device correlation was assessed with Pearson's r. RESULTS: Clear size differences between different types of disk displacement were noted. Interexaminer measurement reliability was 0.78 to 0.84. Agreement concerning the presence of disk displacement was 85% (kappa = 0.68), and the classification of disk displacements was 76% (kappa = 0.60). Intraexaminer measurement reliability was 0.40 to 0.49. Intraexaminer agreement concerning the presence of disk displacement was 76% (kappa = 0.52), and the classification of disk displacements was 62% to 69% (kappa = 0.38 to 0.46). Normal versus bulged disk distinctions demonstrated the most disagreement. The ruler and digitizer correlation coefficient was 0.968. CONCLUSIONS: Different disk types demonstrated distinct size averages. Interexaminer agreement was good concerning disk assessment and measurements. Intraexaminer agreement was lower than expected. A millimetric ruler is an acceptable alternative to digital measurement devices.

Posterior disk displacement: morphologic assessment and measurement reliability--cervical spine.

BACKGROUND: Magnetic resonance imaging (MRI) is often used to assess for disk displacement after manipulation, but limited information about the true incidence of iatrogenic herniations exists. Preliminary data must be obtained concerning the size of different types of displacement to further assess this relationship. The reliability of chiropractic radiologists in assessing disks, and a comparison of measuring devices should be evaluated. OBJECTIVE: To identify average measurements for normal and displaced disks and to assess the reliability of measurements by chiropractic radiologists. STUDY DESIGN: Intraobserver and interobserver reliability study assessing cervical disk displacement on MRI scans. METHODS: Three evaluators assessed the disks on 106 MRI scans. Six categories were assessed and compared. Thirty-seven scans were reassessed for intraobserver comparisons. Interobserver and intraobserver variations and measurement-device correlations were determined. RESULTS: Interexaminer measurement reliability for the 2 devices was 0.80 to 0.84. Intraexaminer reliability ranged from 0.58 to 0.94. Interexaminer and intraexaminer agreement for the presence of disk displacement was 86% (kappa = 0.69) and 78% to 85% (kappa = 0.50-0.67), respectively; for the presence of osteophytes, 92% (kappa = 0.54) and 86% to 95% (kappa = 0.60-0.80); and for the classification of disk displacements, 76% (kappa = 0.53) and 73% to 80% (kappa 0.44-0.61). Distinguishing between normal versus bulged disks demonstrated the greatest classification disagreement. Clear size differences between the types of disk displacement were noted. The ruler and digitizer correlation coefficient was 0.96. CONCLUSIONS: Interexaminer and intraexaminer agreement were good to very good concerning measurements and fair to good concerning disk assessments. Different disk displacement types demonstrated obvious mean size differences. No significant mean difference in measurements between the ruler and the digitizer was noted.

Allochronic speciation, secondary contact, and reproductive character displacement in periodical cicadas (Hemiptera: Magicicada spp.): genetic, morphological, and behavioural evidence.

Periodical cicadas have proven useful in testing a variety of ecological and evolutionary hypotheses because of their unusual life history, extraordinary abundance, and wide geographical range. Periodical cicadas provide the best examples of synchronous periodicity and predator satiation in the animal kingdom, and are excellent illustrations of habitat partitioning (by the three morphologically distinct species groups), incipient species (the year classes or broods), and cryptic species (a newly discovered 13-year species, Magicicada neotredecim). They are particularly useful for exploring questions regarding speciation via temporal isolation, or allochronic speciation. Recently, data were presented that provided strong support for an instance of allochronic speciation by life-cycle switching. This speciation event resulted in the formation of a new 13-year species from a 17-year species and led to secondary contact between two formerly separated lineages, one represented by the new 13-year cicadas (and their 17-year ancestors), and the other represented by the pre-existing 13-year cicadas. Allozyme frequency data, mitochondrial DNA (mtDNA), and abdominal colour were shown to be correlated genetic markers supporting the life-cycle switching/allochronic speciation hypothesis. In addition, a striking pattern of reproductive character displacement in male call pitch and female pitch preference between the two 13-year species was discovered. In this paper we report a strong association between calling song pitch and mtDNA haplotype for 101 individuals from a single locality within the M. tredecim/M. neotredecim contact zone and a strong association between abdomen colour and mtDNA haplotype. We conclude by reviewing proposed mechanisms for allochronic speciation and reproductive character displacement.