Search

Divergence is often ephemeral, and populations that diverge in response to regional topographic and climatic factors may not remain reproductively isolated when they come into secondary contact. We investigated the geographical structure and evolutionary history of population divergence within Sceloporus occidentalis (western fence lizard), a habitat generalist with a broad distribution that spans the major biogeographical regions of Western North America. We used double digest RAD sequencing to infer population structure, phylogeny and demography. Population genetic structure is hierarchical and geographically structured with evidence for gene flow between biogeographical regions. Consistent with the isolation-expansion model of divergence during Quaternary glacial-interglacial cycles, gene flow and secondary contact are supported as important processes explaining the demographic histories of populations. Although populations may have diverged as they spread northward in a ring-like manner around the Sierra Nevada and southern Cascade Ranges, there is strong evidence for gene flow among populations at the northern terminus of the ring. We propose the concept of an "ephemeral ring species" and contrast S. occidentalis with the classic North American ring species, Ensatina eschscholtzii. Contrary to expectations of lower genetic diversity at northern latitudes following post-Quaternary-glaciation expansion, the ephemeral nature of divergence in S. occidentalis has produced centres of high genetic diversity for different reasons in the south (long-term stability) vs. the north (secondary contact).

BACKGROUND The purpose of this study was to estimate the proportion of Chinese cancer survivors experiencing financial hardship and then examine the relationship between material and behavioral financial hardship. METHODS This study surveyed 964 cancer survivors who were 30 to 64 years old and 644 survivors who were 65 years old or older during 2015-2016 (1608 survivors in all). Material financial hardship was measured by whether they had borrowed money because of cancer, its treatment, or the lasting effects of treatment, and behavioral financial hardship was measured by whether they had forgone some cancer-related medical care because of cost. Multivariable logistic regression models were used to examine factors associated with material financial hardship by age group. RESULTS Approximately 44% of the cancer survivors who were 65 years old or older borrowed money or went into debt because of cancer, and 54% of younger patients (P

BACKGROUND China accounts for approximately 27% of global cancer deaths. However, to the authors' knowledge, the lasting effects of cancer and cancer treatments on patients have not been investigated in China. The authors developed a questionnaire, the China Survey of Experiences with Cancer, for Chinese cancer survivors. This article introduces the study design and domains covered in the questionnaire. METHODS The Cancer Survivorship Supplement of the Medical Expenditure Panel Survey (MEPS) was used as a reference to develop the questionnaire. The final in-person surveys were conducted in 2015 and 2016. Samples were chosen through multistage sampling. The authors described the characteristics of the study participants and their cancer experiences. RESULTS At the time of last follow-up, a total of 1166 patients had completed at least 1 component of the survey. Approximately 59% of the cancer survivors were aged ≥60 years. Greater than one-half of the participants had an elementary education level or less (51%) and a yearly family income of

Alliaria petiolata, a strict biennial in North America, can have an annual alternating high abundance of rosettes and flowering plants. We monitored changes in abundance of rosettes and flowering plants in permanent plots (2004–2014). Three times during our study, the alternating yearly cycle was not observed (2007–2008, 2008–2009, and 2013–2014). We concluded stochastic extreme climate events (ECEs), deviating from long‐term climatic data norms (10th or 90th percentile), likely caused negative organism responses. Long‐term data from a local NOAA station located 25 km from our study site included monthly data (1) total precipitation, (2) number of days with >0.13 cm precipitation, and (3) mean and minimum temperatures. September 2007 met the criteria for ECEs for all monthly variables. We first observed A. petiolata on our study site in 1988, and by the early 1990s, it was abundant. To determine whether September 2007 significantly differed from other September (1984–2014), we used six variables related to drought: (1) total precipitation, (2) number of days with precipitation, (3) number of contiguous days without precipitation, (4) mean monthly temperature, (5) mean maximum daily temperature, and (6) the number of days with temperatures >30°C. The first two variables likely increase plant stress as they decrease, whereas stress declines as the remaining variables decrease. We used the six variables to generate a principal component analysis (PCA) biplot. Axes 1 and 2 accounted for 74.3% of the variance. Record‐breaking minimum temperatures (ECEs) for January (2009) and February–March (2014) likely reduced rosette abundance and disrupted reestablishment of alternating high abundance of rosettes and flowering plants. Our data suggest that a single ECE variable, minimum temperature, and multiple ECE variables related to drought likely had negative effects on A. petiolata.

Purpose The Appalachian region presents disproportionately high rates of chronic disease compared to the rest of the United States. Early diagnosis of diabetes through screening is an important step in reducing diabetes complications. This study examines disparities in the use of diabetes screening in Appalachia. Methods We analyzed 2009 and 2010 Behavioral Risk Factor Surveillance System data for 96,111 adults aged ≥45 years from 11 Appalachian states. Based on economic status, Appalachian counties were grouped into distressed (least affluent), at-risk, transitional, and competitive (most affluent). Logistic regression analyses were used to estimate the statistical significance and effect size of factors associated with diabetes screening. Results Competitive counties had the highest rate of diabetes screening (65.4%). At-risk counties had the lowest rate (60.3%), about 7.8% lower compared to competitive counties (P < .001). After adjusting for socioeconomic factors, differences in screening rates between county economic levels in Appalachia were not statistically significant. Among respondents ≥65 years, at-risk counties had an 8.1% lower screening rate compared to competitive counties; this difference was not adequately explained by differences in socioeconomic factors. Screening rates in distressed and transitional counties were not significantly different from competitive counties in unadjusted or adjusted models. Conclusions At-risk counties had significantly lower screening rates than competitive counties. They should receive more policy attention similar to that received by distressed counties. Social policies that improve socioeconomic status and educational attainment, and health policies that reduce barriers to access to care may reduce disparities in diabetes screening rates in the less affluent Appalachian counties.

Purpose Despite being generally accepted that delays in diagnosing breast cancer are of prognostic and psychological concern, the influence of hospital characteristics on such delays remains poorly understood, especially in rural and underserved areas. However, hospital characteristics have been tied to greater efficiency and warrant further investigation as they may have implications for breast cancer care in these areas. Methods Study data were derived from the Kentucky, North Carolina, Ohio, and Pennsylvania state central cancer registries (2006-2008). We then linked Medicare enrollment files and claims data (2005-2009), the Area Resource File (2006-2008), and the American Hospital Association Annual Survey of Hospitals (2007) to create an integrated data set. Hierarchical linear modeling was used to regress the natural log of breast cancer diagnosis delay on a number of hospital-level, demographic, and clinical characteristics. Findings The baseline study sample consisted of 4,547 breast cancer patients enrolled in Medicare that lived in Appalachian counties at the time of diagnosis. We found that hospitals with for-profit ownership (P < .01) had shorter diagnosis delays than their counterparts. Estimates for comprehensive oncology services, system membership and size were not statistically significant at conventional levels. Conclusions Some structural characteristics of hospitals (eg, for-profit ownership) in the Appalachian region are associated with having shorter delays in diagnosing breast cancer. Researchers and practitioners must go beyond examining patient-level demographic and tumor characteristics to better understand the drivers of timely cancer diagnosis, especially in rural and underserved areas.

Purpose To document cancer-related health disparities in Appalachia. Methods The current study investigated disparities in cancer incidence, mortality, and staging between rural Appalachians and those living outside of rural Appalachia. To accomplish this, mortality data for the United States from 1969 to 2011 were obtained from the National Center for Health Statistics (NCHS) using SEER*Stat. These data were used to compare trends in mortality between rural Appalachians, urban Appalachians, rural non-Appalachians, and urban non-Appalachians. Cancer incidence trends, staging, and survivorship data were compared across regions using the SEER-18 Program, which represented 28% of the US population and includes 2 Appalachian states: Georgia and Kentucky. Results Cancer mortality rates declined in all regions, but disparities remained such that rural Appalachia has the highest incidence, while urban non-Appalachia has the lowest. In all but 1 state, rural Appalachians had higher cancer mortality rates than urban non-Appalachians. Cancer incidence declined for all regions except rural Appalachia. Rural Appalachians had lower rates of early stage breast cancer diagnoses than their urban non-Appalachian counterparts. Finally, rural Appalachians had lower 3- and 5-year survival rates than their urban non-Appalachian counterparts. Conclusions Rural Appalachians are faced with poorer cancer-related health outcomes across the continuum of cancer care. A systematic effort is needed to reduce the burden of cancer for rural Appalachia. Additional research should explore reasons for the disparities that were observed.

Purpose To examine local definitive therapy for non-metastatic breast cancer using the Centers for Disease Control and Prevention’s National Program of Cancer Registries Patterns of Care Breast and Prostate Cancer (POCBP) study.

Purpose The objective was to examine the impact of regular primary care encounters (PCE) on early breast cancer detection in an Appalachian sample of Medicare beneficiaries diagnosed 2006-2008. Determinants of PCE were investigated and a mediation analysis was conducted where PCE was a mediator to cancer stage. Methods A total of 3,589 cases were identified from Appalachian areas in Pennsylvania, Kentucky, Ohio, and North Carolina, and health care services were examined 2 months to 2 years prior to diagnosis. A regular care PCE variable was constructed with 4 ordinal levels: none, any, “annual,” and “semi-annual.” Association of PCE with stage, mortality and covariables was conducted using ordinal logistic regressions and Cox Proportional Hazards survival models. Results Sixty-eight percent of the cases had semi-annual PCE. Regular PCE was strongly associated with late-stage cancer rates (39%-13% by increasing PCE level, P < .0001) and 5-year all-cause mortality (42%-24%, P < .0001). Subgroup analysis revealed variations by hypertension and urban status, with nonhypertensives with no PCE being at particularly increased risk. Significant determinants of PCE included age, rural/urban status, comorbidity, dual Medicaid insurance, Appalachian region economic classification, state, select comorbidities, hypertension, and minimum distance to provider. Mediation analysis results were consistent with lower number of comorbidities leading to increased late cancer detection due to patients having a decreased PCE. Conclusion PCE is an important determinant of cancer detection, with a dose-response relationship. Variations exist by geography and hypertension. Comorbidity may influence both PCE and late-stage rates with partial mediation through PCE.

Purpose The mortality rate of laryngeal cancer has been trending downward with the use of more effective surgical, radiation, and systemic therapies. Although the best treatment for this disease is not entirely clear, there is a growing consensus on the value of primary radiotherapy as an organ preservation strategy. This study examines urban-rural differences in the use of radiotherapy as the primary treatment for early stage laryngeal cancer in Pennsylvania. Experimental Design The sample was drawn from the Pennsylvania tumor registry, which lists 2,437 laryngeal cancer patients diagnosed from 2001 to 2005. We selected 1,705 adults with early stage squamous cell carcinoma of the larynx for our analysis. Demographic data and tumor characteristics were included as control variables in multivariate analyses. Rurality was assigned by ZIP code of patient residence. Results Controlling for demographic and clinical factors, rural patients were less likely than urban patients to receive radiotherapy as the primary treatment modality for early stage larynx cancer (OR 0.740, 95% CI 0.577-0.949, P = .0087). No other associations between rural status and treatment choice were statistically significant. Conclusions Relatively fewer rural patients with larynx cancer are treated primarily with radiation therapy. Further investigations to describe this interaction more thoroughly, and to see if this observation is found in larger population data sets, are warranted.

Objectives: To explore the relationship between level and type of comorbidity and guideline-concordant care for early-stage breast cancer. Design: Cross-sectional. Setting: National Program of Cancer Registry (NPCR) Breast and Prostate Cancer Patterns of Care study, which re-abstracted medical records from 2004 in seven cancer registries. Participants: Individuals with stage 0�III breast cancer. Measurements: Multicomponent guideline-concordant management was modeled based on tumor size, node status, and hormone receptor status, according to consensus guidelines. Comorbid conditions and severity were measured using the Adult Comorbidity Evaluation Index (ACE-27). Multivariate logistic regression models determined factors associated with guideline-concordant care and included overall ACE-27 scores and 26 separate ACE comorbidity categories, age, race, stage, and source of payment. Results: The study sample included 6,439 women (mean age 58.7, range 20�99; 76% white; 44% with no comorbidity; 70% estrogen- or progesterone-receptor positive, or both; 31% human epidermal growth factor receptor 2 positive). Care was guideline concordant in 60%. Guideline concordance varied according to overall comorbidity burden (70% for none; 61% for minor; 58% for moderate, 43% for severe; P < .05). In multivariate analysis, the presence of hypertension (odds ratio (OR) = 1.15, 95% confidence interval (CI) = 1.01�1.30) predicted guideline concordance, whereas dementia (OR = 0.45, 95% CI = 0.24�0.82) predicted lack of guideline concordance. Older age (?50) and black race were associated with less guideline concordance, regardless of comorbidity level. Conclusion: When reporting survival outcomes in individuals with breast cancer with comorbidity, adherence to care guidelines should be among the covariates.

To model the relationship of an area-based measure of a breast cancer screening and geographic area deprivation on the incidence of later stage breast cancer (LSBC) across a diverse region of Appalachia.Central cancer registry data (2006-2008) from three Appalachian states were linked to Medicare claims and census data.Exploratory spatial analysis preceded the statistical model based on negative binomial regression to model predictors and effect modification by geographic subregions.Exploratory spatial analysis revealed geographically varying effects of area deprivation and screening on LSBC. In the negative binomial regression model, predictors of LSBC included receipt of screening, area deprivation, supply of mammography centers, and female population aged75 years. The most deprived counties had a 3.31 times greater rate of LSBC compared to the least deprived. Effect of screening on LSBC was significantly stronger in northern Appalachia than elsewhere in the study region, found mostly for high-population counties.Breast cancer screening and area deprivation are strongly associated with disparity in LBSC in Appalachia. The presence of geographically varying predictors of later stage tumors in Appalachia suggests the importance of place-based health care access and risk.

To examine the relationship between radiation therapy resources and guideline-concordant radiotherapy after breast-conserving surgery (BCS) in Kentucky.The SEER registry and Area Resource File provided county-level data describing cancer care resources and socioeconomic conditions of Kentucky residents.The outcome variable was rate of BCS without radiotherapy in each county for 2000-2007. Eight-year weighted average rates of radiation therapy providers and hospitals per 100,000 residents were explanatory variables of interest. Exploratory spatial data analyses and spatial econometric models were estimated.Appalachian counties in Kentucky had significantly fewer radiation oncologists, hospitals with radiation therapy facilities, and surgeons per 100,000 residents than non-Appalachian counties. The likelihood of BCS without radiation was significantly higher among Appalachian compared to non-Appalachian women (42.5 percent vs. 29.0 percent, p .001). Higher proportions of women not receiving recommended radiotherapy after BCS were clustered in Eastern Kentucky around Lexington. This geographic disparity was partially explained by significantly fewer radiation therapy facilities in Appalachian Kentucky in adjusted analyses.Scarce radiation therapy resources in Appalachian Kentucky are associated with disparities in receipt of guideline-concordant radiotherapy, suggesting that policy action is needed to improve the cancer treatment infrastructure in disadvantaged mountainous areas.

Diabet. Med. 29, e67–e74 (2012) Abstract Aims Post-hoc evaluation of relationships between first-year change in glycaemic control (HbA1c) and change in patient-reported outcomes among ACCORD health-related quality of life (HRQoL) substudy participants. Methods Data from 2053 glycaemia-trial subjects were analysed. We assessed physical and mental health status (36-Item Short Form Health Survey, Version-2), symptom count and severity (Diabetes Symptoms Distress Checklist) and treatment satisfaction (Diabetes Treatment Satisfaction Questionnaire). Linear mixed models were used to test relationships between 1-year changes in HbA1c and patient reported outcomes sequentially adjusting for correlates (baseline characteristics, baseline patient reported outcomes, treatment assignment, frequency of clinical contact and post-randomization weight change plus new complications). Results Poorer baseline control of HbA1c and cardiovascular disease risk factors predicted greater one-year improvements in treatment satisfaction. Similarly, poorer baseline patient reported outcome scores all individually predicted greater 1-year improvement in that same outcome. Accounting for baseline and post-randomization characteristics and treatment arm, 1-year change in HbA1c was unrelated to changes in overall physical or mental health; however, every one percentage-point (10.9 mmol/mol) reduction in HbA1c was associated with lower symptom count (β = 0.599; P = 0.012), lower symptom distress (β = 0.051; P = 0.001), and higher treatment satisfaction (β = −2.514; P

Purpose: Vanishing Optotype letters have a pseudo high-pass design so that the mean luminance of the target is the same as the background and the letters thus ‘vanish’ soon after the resolution threshold is reached. We wished to determine the variability of acuity measurements using these letters compared to conventional letters, and in particular how acuity is affected by the number of alternatives available to the subject. Methods: Acuity was measured using high contrast letters of both conventional and Vanishing Optotype design for three experienced normal subjects. Thresholds were determined for central vision in a forced choice paradigm for two alternatives (2AFC; AU and OQ), 4AFC (AQUO), 6AFC (QUANGO) and 26AFC (whole alphabet) using a QUEST procedure. Three measurements were made for each condition. Results: Threshold letter size was always larger for the Vanishing Optotypes than conventional letters, although the size of this difference (0.11–0.34 logMAR) depended on the number of alternatives and what they were. The effect of the number of AFC, and the individual letters employed, was smaller for the Vanishing Optotypes, implying that they are more equally legible than conventional optotypes. Variability was also lower for the Vanishing Optotype sets (0.01–0.03 logMAR) than the conventional letter sets (0.03–0.06). Conclusions: The smaller effect of the number of letter alternatives, combined with more equal discriminability and lower threshold variability, implies that Vanishing Optotypes may be appropriate targets from which to design letter charts to measure small clinical changes in acuity.

We studied the effects of hand weeding of second-year plants of the biennial garlic mustard (Alliaria petiolata) on first-year plants (seedlings) and native ground layer vegetation. Garlic mustard is a Eurasian species that has invaded deciduous forest ground layers in eastern North America. Treatments consisted of a control and an early or late weeding of second-year garlic mustard. The early treatment (early March) was applied before garlic mustard seeds had germinated and when most native species were dormant. The late treatment (mid-May) occurred after plants had bolted, flowering was occurring, and most native species and new garlic mustard seedlings were actively growing. Pre-treatment data were obtained in 2004 and treated and control plots were sampled in 2005, 2006, and 2007. No significant treatment effects were observed in 2004 or 2005. In 2006, mean cover of first-year plants was higher in the early weeding treatment than in the late weeding treatment and control. In 2007, mean cover of first-year garlic mustard was higher in the control than in either of the two weeding treatments. There were no significant treatment effects in any year on native vegetation cover, bare ground, or the five most abundant native species. Our data indicate that (1) late weeding of garlic mustard provided more effective control than early weeding because late weeding allows second-year plants to compete with garlic mustard seedlings for a longer period of time and (2) competition between first- and second-year plants is responsible for alternating dominance of first-year and second-year garlic mustard plants.

This article describes a direct method for the exact computation of 3nj symbols from the defining series, and continues discussing properties and asymptotic formulas focusing on the most important case, the 6j symbols or Racah coefficients. Relationships with families of hypergeometric orthogonal polynomials are presented and the asymptotic behavior is studied to account for some of the most relevant features, both from the viewpoints of the basic geometrical significance and as a source of accurate approximation formulas, such as those due to Ponzano and Regge and Schulten and Gordon. Numerical aspects are specifically investigated in detail, regarding the relationship between functions of discrete and of continuous variables, exhibiting the transition in the limit of large angular momenta toward both Wigner's reduced rotation matrices (or Jacobi polynomials) and harmonic oscillators (or Hermite polynomials). © 2009 Wiley Periodicals, Inc. Int J Quantum Chem 110: 731-742, 2010

I compared growth and arbuscular mycorrhizal fungal (AMF) colonization of two prairie grasses (Wild rye [Elymus canadensis] and Little bluestem [Schizachyrium scoparium]), an early- and a late-dominating species in prairie restorations, respectively, grown in soil from restored prairies of differing age, soil characteristics, and site history. There were no consistent patterns between restoration age and soil inorganic nutrients or organic matter. The oldest restoration site had higher soil mycorrhizal inoculum potential (MIP) than 2- and 12-year-old restorations. However, MIP did not translate into actual colonization for two species grown in soils from the three restorations, nor did MIP relate to phosphorus availability. There were significant differences in root mass and colonization among Wild rye plants but not among Little bluestem plants grown in soils from the three restorations. Wild rye grown in 2-year-old restoration soil had significantly higher AMF colonization than when it was grown in soils from the 12- and 17-year-old restorations. Wild rye grown in 2-year-old restoration soil also had higher colonization than Little bluestem grown in 2- and 12-year-old restoration soils. Little bluestem had no significant correlations between shoot biomass, root biomass or colonization, and concentrations of soil P, total N, or N:P. However, for Wild rye, total soil N was positively correlated with root mass and negatively correlated with colonization, suggesting that in this species, mycorrhizae may affect N availability. Collectively, these results suggest that soil properties unrelated to restoration age were important in determining differences in growth and AMF colonization of two species of prairie grasses.

Maintenance of symptom control in Parkinson's disease (PD) requires continuous titration of medication and addition of multiple therapies over the course of the disease. Adherence to medication is vital to symptom control and key to maximizing the efficacy of existing therapies. However, adherence is compromised by a variety of factors, including motor symptoms, complex dosing regimens, multiple medications, and lack of patient/physician awareness of the impact and prevalence of suboptimal adherence. This retrospective, longitudinal cohort study assessed the prevalence of suboptimal adherence [measured as the medication possession ratio (MPR)] to PD medications, and its impact on the worsening of PD symptoms (measured as increase in monotherapy dose, augmentation of therapy, PD-related emergency department visit, or hospitalization), in a Medicare Health Maintenance Organization population in the United States. Irrespective of the MPR threshold chosen, a high percentage of patients were categorized as suboptimally adherent to their PD medications, and patients with suboptimal adherence to their PD medications had higher risks of worsening of PD symptoms, compared with those who were adherent. Increased awareness of both the magnitude and impact of suboptimal adherence to PD medications, coupled with dosage simplification and a unified effort by healthcare professionals and patients, may improve adherence to PD medications and ultimately improve symptom control.

Bear River, the largest river in the Great Basin, had some of its flow diverted into Bear Lake through a series of canals constructed between 1911 and 1918, turning Bear Lake into a reservoir. The prediversion lake had an unusually high Mg2+ :C a2+ ratio (38 by weight), which resulted in precipitation of CaCO3 as aragonite. The amount and mineralogy of the carbonate did not change immediately after the diversion, but during the middle of the 20th century, high-Mg calcite began to precipitate. In contrast, at the time of diversion there were very distinct changes in the isotopic composition of the carbonate that clearly define the time of diversion within the sediments. Sedimenttrap studies show that the CaCO3 polymorph that precipitates in the epilimnion of the lake today is high-Mg calcite. Samples in sediment traps placed 2 m above the bottom of the lake in 45 m of water (bottom traps) contain predominantly aragonite and quartz, with lesser amounts of high-Mg and low-Mg calcite and dolomite. Isotopic evidence from the sediments shows that the aragonite that accumulated in the bottom sediment traps and that constitutes the bulk of postdiversion sediments is reworked and redistributed from shallow sites to deep sites.

Diet selection among several prey types present in a dense aggregation, permitting a predator to become satiated without changing patches, may be important for predators that can eat many small prey items in a single bout. Choice in this scenario differs from that in optimal foraging models for sequential diet choice model and simultaneous choice models when travel time between patches is needed. Furthermore, satiation and depletion effects may be important in dense prey aggregations. We predicted that in dense prey aggregations, predators should eat the most profitable prey first, switching to smaller prey as larger ones become depleted and predators become satiated, and that prey below some minimum profitability should be rejected. When large numbers of prey of varying sizes were presented simultaneously, broad-headed skinks (Eumeces laticeps) preferentially consumed large crickets, ate some medium-sized crickets late in ingestion sequences, but ate no small crickets. Prey depletion, with selection of the currently most profitable prey type, appears to account for much of observed prey switching, and satiation may contribute. When four crickets of each of four sizes were presented, lizards ate largest first, then medium-sized. Some then ate small crickets, but none ate very small crickets. These observations and exclusion of small crickets from the diet by many lizards when larger ones were unavailable support the predictions. In tests with three sizes of juvenile mice presented singly, the smallest were attacked at shortest latency and eaten, medium-sized mice were attacked at greater latency but could not be subdued, and large mice were not attacked. These data suggest that as prey become too large to subdue and eat readily, profitability declines until they are excluded from the diet. Unsuccessful attacks on medium-sized mice suggest that lizards had to learn their own capabilities with respect to a novel prey type.

Summary 1 Phragmites australis is an invasive grass that has increased dramatically in distribution and abundance within the USA in the last 100 years. This study determined the effect of nitrogen addition on the growth of this invasive species compared with an indigenous competitor species, Spartina pectinata. 2 Twenty plants from each of three Illinois (USA) populations were collected and planted in the same garden in April 2001 and grown until August 2002. Following a year of growth in the garden, high-nitrogen (45 g N m−2) and low-nitrogen (5 g N m−2) treatments were applied to plants grown from paired rhizome cuttings from each plant. A single S. pectinata plant was grown with each P. australis. In August 2002, plants were harvested and above- and below-ground biomasses were determined for both species. 3 Mean (± SE) P. australis above- and below-ground biomasses were significantly higher in the high-nitrogen treatment (68·4 ± 2·6 g and 39·0 ± 4·5 g, above- and below-ground, respectively) than the low-nitrogen treatment (37·3 ± 2·0 g and 25·5 ± 4·5 g). There were no differences in S. pectinata above- and below-ground biomasses between high- (46·8 ± 3·2 g and 71·4 ± 9·6 g) and low- (45·4 ± 3·5 g and 50·3 ± 6·5 g) nitrogen treatments. The ratio of P. australis to S. pectinata biomass was used to compare the relative response of each species between nitrogen treatments; the mean ratio of P. australis to S. pectinata for the high-nitrogen treatment (2·72 ± 0·499) was significantly higher than the low-nitrogen treatment (1·83 ± 0·42). 4 Synthesis and applications. This study supports the hypothesis that P. australis benefits from increased nitrogen, and may be more likely to displace S. pectinata in nitrogen-rich environments. Our study also confirms the importance of nitrogen in affecting the interactions between invasive and native plants. Control of P. australis may be aided by nutrient management.

Previous studies using polychromatic gratings have shown that the peripheral grating contrast sensitivity function is significantly different when the task is resolution rather than detection. Specifically, in the middle frequency range, while resolution acuity drops suddenly to zero, detection performance continues up to much higher frequencies, accompanied by observations of aliasing. We wanted to determine if the same holds true for blue-cone isolating gratings in either foveal or peripheral vision. Contrast sensitivity function (CSFs) were measured at the fovea and 20 degrees eccentricity in the temporal retina under conditions of short-wavelength-sensitive (SWS)-cone pathway isolation using a two-alternative forced choice paradigm. The detection and resolution CSF were identical at the low frequency end but at higher frequencies resolution sensitivity falls abruptly while contrast detection remained possible till higher frequencies [cut-off frequencies: fovea detection 6.0 cycles (degree)(-1), resolution 4.6 cycles (degree)(-1); periphery detection 1.6 cycles (degree)(-1), resolution 1.05 cycles (degree)(-1)]. Aliasing was observable when spatial frequency exceeded the resolution limit. Medium/high contrast blue-cone-mediated resolution acuity is sampling limited in both the fovea and periphery. Previous studies of blue-cone contrast sensitivity which employed a detection task do not reflect the true resolution limit.

Jack pine barrens, once common in northern lower Michigan, mostly have been converted to managed jack pine plantations. Management of the disturbances associated with logging provides the opportunity to maintain the unique plant assemblages of jack pine barrens and nest habitat of the federally endangered Kirtland's warbler. Studies indicate that Carex pensylvanica can develop into dense mats and strongly compete with other barrens species such as Vaccinium angustifolium, which seem to be important species for Kirtland's warbler nest locations. According to forest managers, the most important factors facilitating high cover of V. angustifolium and reducing cover of C. pensylvanica are the amount of shade produced by tree crowns before harvest (pre-harvest shade), the length of time between harvest and planting (planting delay), and fire. We found that high or low levels of pre-harvest shade had no effect on cover of either V. angustifolium or C. pensylvanica. Planting delays of at least three years following prescribed burns generally increased cover of V. angustifolium in forest plots, which are important for warbler nesting. Analysis of community composition in openings indicated that burning enhanced the growth of barrens species. We found only weak evidence for a negative correlation between the cover of V. angustifolium and C. pensylvanica on our study sites. The openings created in the jack pine plantation are important refugia for barrens flora that would likely be lost under forests managed strictly for jack pine. Maintenance of jack pine barrens flora and Kirtland's warbler nest habitat is possible within the context of a heavily managed forest plantation system.

Purpose: Previous studies of optical blur in perimetry have measured the effect of foveal refractive error on peripheral perimetric detection thresholds. Since peripheral refractive error can be significantly different from that of the fovea we wished to remove the ambiguity of previous results by correcting the actual peripheral refractive error first before adding blur. Methods: We measured detection thresholds in the fovea and at 30 degrees in the horizontal temporal field in two trained observers. Peripheral refractive error was determined at each location and thresholds measured at the same locations for stimuli ranging in size from 0.2 to 6.4 degrees and refractive errors between ±4.00 diopters. Results: Foveal thresholds increased immediately with increasing refractive error, particularly for smaller stimulus sizes. At 30 degrees, thresholds for smaller stimuli were less affected by defocus initially and then increased more sharply. Larger stimuli were relatively unaffected by defocus such that when stimulus size reached 1.6 degrees there was little or no increase in threshold for refractive error between ±4.00 diopters. Conclusions: Peripheral refractive error, largely forgotten by perimetrists, has a significant effect on performance, particularly for smaller stimuli. Differences in foveal vs peripheral viewing can be explained by differences in ganglion cell receptive field sizes.

We studied vegetation change of a remnant barrens in southern Illinois over twenty-five years. The study area was periodically burned between 1969 and 1993, but fire was excluded for a 16-year period (1974-1989). During the study, the barrens supported a mixture of species whose preferred habitats ranged from prairie and open woodlands to closed forest communities. The herbaceous vegetation may be on a trajectory characterized by increasing dominance of woodland species and declining prairie species. Fire management temporarily reversed this trend, but it continued once fire was excluded. Reintroduction of prescribed burning in 1990-1993 altered the vegetation trajectory but not back toward a species composition comparable to that present on the site before cessation of fire management after 1973. Following interruption of prescribed burning, tree basal area more than doubled, and density showed a 67% increase between premanagement conditions in 1968 and 1988. Salix humilis (prairie willow) density had significant negative correlations with tree density and basal area. However, there was no consistency in response of shrub species on the site to the varied site conditions over time. Fire management on the site may not recover the historic barrens that occurred on the site. Nevertheless, consistent fire management will drive vegetation changes toward increasing abundance of prairie and open woodland species that would otherwise be lost without burning.

This study tested the hypothesis that married psychiatric outpatients would have lower total health services expenditures than divorced or separated patients. Chart review of the 471 individuals attending an academic medical center outpatient psychiatric clinic during 1994 identified 131 married, 40 separated, and 93 divorced patients. Separated men had significantly higher average total charges ($16,890) than married ($5,279) or divorced ($5,539) men by one-way ANOVA (p < .05). The nonparametiric Mann-Whitney test also showed that separated men had higher charges than married or divorced men. There were no differences between marital status groups for women.

Differences in growth responses, tissue and soil inorganic nutrients, and mycorrhizal relationships of four herbaceous species were studied on burned and unburned sandhill sites in south-central Florida, USA. Three species, (Aristida stricta, Liatris tenuifolia var. laevigata, and Pityopsis graminifolia) responded positively to conditions following the burn by increased vegetative growth and flowering. The fourth species, Balduina angustifolia, is a fire-sensitive biennial and its firstyear rosettes were, with an occasional exception, unable to survive or resprout following fire. Availability of all soil inorganic nutrients examined (Ca, K, Mg, and P) was low, as were total nitrogen, soil organic matter, and pH. There was a slight nutrient pulse of phosphorus into the soil following burning. For two species ( Aristida and Liatris), shoot tissue concentrations of several inorganic nutrients (especially N and P) were higher on the burned site than the unburned site following burning. These differences generally dissipated over time since burning. The high concentration of tissue nutrients postburn followed by a decline on the burned site may result from rapid nutrient uptake after fire and dilution of this concentration following restoration of plant mass. Despite low levels of soil inorganic nutrients, including phosphorus, mycotrophy was absent or weakly developed among the herbaceous species examined, except for the tap-rooted Balduina angustifolia. Colonization of host plants by vesicular mycorrhizal fungi was unaffected by burning. Mycorrhizal inoculum potentials of sandhill soil were extremely low, varying seasonally from (mean 6 1 SE) 0.3 6 0.2 to 3.8 6 0.7%.

Low-vagility organisms that specialize on transitory successional habitats may be especially dependent upon habitat connectivity to maintain population viability. We analyzed the theoretical intrinsic connectivity of successional landscapes (i.e., the natural juxtaposition of similar habitats that allows dispersal) as a function of patch geometry coupled with the disperser’s habitat specificity. Habitat specialists living in poorly connected landscapes (approximating hexagonal patches) have only a 26.5% chance of colonizing a new site when their resident patch becomes unsuitable. In contrast, generalists living in well connected landscapes can virtually always colonize a new site when needed. We infer from our simulation that for some habitat specialists, such as the rare, endemic Florida scrub lizard (Sceloporus woodi), anthropogenic control of successional dynamics for commercial logging may significantly reduce intrinsic connectivity. Lizard population viability may now depend upon the extrinsic connectivity provided by artificial corridors. However, the use of corridors will not serve as a general solution to the problem of anthropogenically reduced intrinsic connectivity until key logistical design problems have been resolved. Moreover, efforts to enhance intrinsic connectivity by modifying patch geometry may produce undesirable edge effects and conflict with old-growth preservation. Future research should focus on developing spatially explicit corridor models, documenting natural levels of intrinsic connectivity, quantifying anthropogenic disruption of natural connectivity, and describing species-specific mechanisms of inter-patch dispersal. Organismos de baja dispersion que se especializan en habitats sucesionales transitorios pueden depender especialmente de la conectividad del habitat para mantener su viabilidad poblacional. Analizamos la conectividad intrinseca teorica de paisajes sucesionales (i.e., la yuxtaposicion natural de habitats similares que permite la dispersion) como una funcion de geometria de parches combinada con la especificidad de habitat del dispersante. Los especialistas que viven en paisajes mal conectados (cercanos a parches hexagonales) solo tienen una probabilidad de 26.5% de colonizar un nuevo sitio cuando su parche deja de ser adecuado. En contraste, los generalistas que viven en paisajes bien conectados virtualmente pueden siempre colonizar un nuevo sitio cuando necesario. De nuestra simulacion, inferimos que, para algunos especialistas como la rara y endenuca kagartuha de Florida (Sceloporus woodi), el control antropogenico de la dinamica sucesional con fines comerciales puede reducir la conectividad intrinseca significativamente. La viabilidad poblacional de lagartijas puede entonces depender de la conectividad extrinseca proporcionada por corredores artificiales. Sin embargo, el uso de corredores no sera una solucion general al problema de la reduccion antropogenica de la conectividad intrinseca hasta que se resuelvan algunos problemas claves de diseno logistico. Mas aun, los esfuerzos para incrementar la conectividad intrinseca mediante la modificacion de la geometria de parche pueden tener efectos colaterales indeseables y chocar con la preservacion de bosques maduros. Investigaciones futuras deben enforcarse a desarrollar modelos de corredores espacialmente explicitos, a documentar niveles naturales de conectividad intrinseca, cuantificar la transformacion antropogenica de la conectividad natural y en la descripcion de mecanismos especifos de dispersion entre parches.

Alliaria petiolata (garlic mustard), an exotic plant species, has invaded woodlands in several areas in mid-western and northeastern United States and adjacent Canada, and it is displacing the indigenous under-story flora. This study was conducted to provide information about the species' biology that might be useful in controlling its spread in native woodlands. The plant is a strict biennial in North America, spending the first year of growth as a basal rosette. This period of relatively slow growth is followed by a period of rapid shoot elongation (1.9 cm/day) during early spring of the second growing season. The plant is capable of cross- and self-pollination, although pollination and stigma receptivity occur before the flower is open, so autogamy is the most likely breeding system. Garlic mustard invests 20.4% of its biomass in reproductive effort, with an annual seed rain of 15,000 seeds/m2. Seed dispersal from fruits begins in early July and continues into October. Most seeds germinate in the spring following the year in which they were produced. Seedling recruitment is high (8.3–18.0 seedlings/cm2), but only about 7.5% of the plants survive to maturity. The success of the plant in invading woodlands appears to be related to (1) its autogamous breeding system that allows a single individual, or a few individuals, to establish populations of genetically similar but interfertile individuals; (2) high seed production, permitting establishment of large numbers of individuals; and (3) rapid growth during the second growing season, which increases its competitive ability. Because of garlic mustard's ability to occupy understory habitats successfully, it may be unrealistic to expect to eliminate the plant from many habitats it has already invaded.

Previous research on rural and urban differences in risk of mortality has been inconclusive. This article used data from the National Longitudinal Mortality Study to establish whether all-cause mortality risk among persons 55 years and older varies by degree of urbanization, controlling for the potential sociodemographic confounders of age, gender, race/ethnicity, education, income, and marital status. Using the Cox Proportional Hazards Regression Procedure, the authors found that persons living in the most rural locales and those living in rural communities in standard metropolitan statistical areas (SMSAs) have the lowest risk of mortality, while those living in SMSA central cities had the highest risk of dying during the study period. The protective effect of rural residence declines in older age cohorts.

The growth response of prairie switchgrass (Panicum virgatum L.) was compared in strip mine spoil amended with various levels of anaerobically digested waste-activated sewage sludge (0, 56, 111, 222, or 333 dry Mg ha -1 ) and commercial fertilizer, pure sludge, and glasshouse soil. Plants were grown in a growth chamber and substrates were maintained at field capacity during the study. Soluble salt concentrations of the substrates increased linearly as a function of sludge amendment and were within the range known to inhibit the growth of many plant species at the high levels of sludge application. There was, however, a linear response of biomass production to increasing levels of sludge amendment. Maintaining substrates at field capacity apparently prevented the high concentration of soluble salts from inhibiting plant growth. The increased biomass yield associated with sludge application was likely due to the increased availability of inorganic nutrients associated with sludge amendment.

Stride parameters and gaits were examined in seven species of teiid lizards in an attempt to understand size-dependent variation of locomotor patterns. Scaling of body dimensions to body mass revealed that axial measures conformed to geometric similarity, whereas the limb segments exhibited an allometry which was statistically significantly less than geometric similarity. Variations in the relationships between stride lengths, stride frequencies and duty factors (% of the stride that foot contacts ground) represented locomotor specializations and were not strictly size-dependent among species. At body length equivalent velocities, stride length and stride frequency scaled to body mass0.40±0.06 and 0.09±0.03, respectively. Cost during locomotion at body length equivalent velocities could be estimated by the square of the product of stride length and stride frequency. Plotting the cost during locomotion for geometrically similar lizards against body mass yielded an estimate of the cost during locomotion that was proportional to mass0.62±0.11. An estimate of the mass-specific cost during locomotion at body length-equivalent velocities scales to mass−0.38±0.11. Because the limbs of these lizards exhibit an allometry less than geometric similarity, a correction of the estimate of the mass-specific cost during locomotion could be obtained by factoring in the effect of increased locomotor costs associated with relatively shorter pelvic limbs in larger lizards. The allometrically corrected estimate of the mass-specific cost during locomotion was proportional to mass−0.31. This estimated regression, which is the relatiue cost of transport for a single, morphologically conservative family of lizards, predicts a slope quite close to that derived from studies of oxygen requirements during locomotion in lizards of several families (slope= -0.28, John-Alder, Garland & Bennett, 1986) and in mammals (slope= -0.32, Taylor, Heglund & Maloiy, 1982).

The height of white-flowered trillium (Trillium grandiflorum) is a useful indicator of deer browsing intensity. In their foraging activities deer select larger plants over smaller plants. Because flowering plants are larger than nonflowering plants, the number of plants in flower decreases with increasing browsing intensity. As browsing intensity increases, the height of the Trillium becomes shorter in successive growing seasons, presumably due to the loss of photosynthetic capacity and reduction in belowground re- sources. Trillium stem height was positively correlated with reproductive output by pe- rennial herbaceous plants and negatively correlated with the percent of the herbaceous understory that is browsed. This indicates change in stem height is an indication of the general status of the herbaceous flora as influenced by deer browsing. Based on deer pop- ulation densities associated with study sites supporting Trillium populations with stable stem heights and flowering plants, maintenance of deer densities of 4-6 individuals/km2 is recommended for deciduous forests in northeastern Illinois. In eastern United States, research workers who assume they are studying relatively undisturbed sites should be aware that intense deer browsing may have imposed an alteration on their study sites.

In prairie restoration, use of seeds from nonlocal sources has been of concern to restorationists. We examined the specificity between vesicular-arbuscular mycorrhizal fungi obtained from a single location and little bluestem obtained from three localities. Seed was obtained from three sources: (1) a commercial seed supplier in Nebraska, (2) Sand Ridge State Forest (SRSF), Mason County, Illinois, the site from which the experimental soil containing the mycorrhizal inoculum was obtained, and (3) Sand Prairie Scrub Oak Nature Preserve (SPSO), 32 km southwest of SRSF. Plants were grown in three substrates: (1) autoclaved soil, (2) autoclaved soil to which a mycorrhizal fungal-free sieving of nonautoclaved soil was added, and (3) nonautoclaved soil. All plants grown in nonautoclaved soil were colonized by mycorrhizal fungi, whereas none of those grown in other substrates were colonized. Plants grown from SRSF seeds produced significantly (p < 0.05) more biomass than those grown from Nebraska seeds (X± SE, SRSF = 0.54 ± 0.04 g, SPSO = 0.49 ± 0.03 g, Nebraska = 0.37 ± 0.03 g). Plants grown in nonautoclaved soil, regardless of seed source, produced less biomass (0.27 ± 0.02 g) than plants grown in autoclaved soil (0.58 ± 0.03 g) or autoclaved soil plus sievings (0.59 ± 0.03 g). The results provide no clear indication of a host-endophyte specificity. However, the data suggest that the local genotypes of S. scoparium are better adapted to their native soil environment than are genotypes from other localities.

Little bluestem grass Schizachyrium scoparium ([Michx.] Nash) plants were grown under field conditions for 2 years in soils fumigated with methyl bromide and chloropicrin, or in unfumigated soil, and treated with supplemental inorganic nutrients (bases calcium and magnesium) phosphorus, nitrogen, and potassium. Most differences in measured plant responses were due to interactions between fumigation and nutrient treatments. These included biomass production, root mass per unit length (,ug/cm), root lengths, flowering culm production, percent colonization, colonized root length, and spore production in rhizosphere soil. Plants generally responded to mycorrhizal fungal colonization by reducing total root length and producing thicker roots. Treatment ofplants with bases appeared to profoundly affect the mycorrhizal association by reducing sporulation of vesicular-arbuscular mycorrhizal fungi and increasing colonization. When fumigated or unfumigated soils were considered separately, base-treated plants produced more biomass than other treatments. Base-treated plants grown on unfumigated soil had more flowering culms and longer colonized root lengths than all other plants. Percent colonization by mycorrhizal fungi and colonized root length were positively correlated with phosphorus/nitrogen ratios, but the ratio was not correlated with plant biomass production. This suggests that phosphorus is not a limiting nutrient in our soil and investment in a mycorrhizal association may not result in enhanced plant growth. The base-nutrient effects may indicate a need to reevaluate earlier studies of macro nutrient effects that did not take into account the role played by calcium and magnesium in assessing fungus-host plant interactions.

Summary The development of an amoeba into a plasmodium involves extensive changes in cellular organisation and gene expression. The genetic basis of a number of recessive mutations that block plasmodium development has been elucidated. The stage at which development becomes abnormal has been determined for all the mutants, as has the terminal phenotype. In order to investigate the changes in gene expression that accompany plasmodium development, a cDNA library has been made using RNA isolated from cell populations in which development was occurring.

Energy budgets for the wide—foraging "arthropodivorous" lizard Cnemidophorus tigris were constructed for the reproductive season using doubly labeled water measurements of field metabolic rate (FMR). Rates of body mass change, clutch sizes, and clutch intervals were also investigated. FMRs of both sexes (males, 298 J · g—1 · d—1; females, 247 J · g—1 · d—1) were greater in the reproductive season than during the postreproductive season. This was not due to differences in resting metabolism, but, instead, was due to higher activity costs during the reproductive season. Although males had significantly higher FMR than females, males and females had similar feeding rates (as reflected by water influx rates). The ratio of energy intake to expenditure was higher in females than in males. Females produced eggs but did not grow. Large males did not grow, but small 1st—yr males similar in size to females did grow. Females laid at least two consecutive clutches during a single reproductive season; clutch interval ...

Tree species composition and density were monitored in closed oak-hickory forest and forestprairie edge for a period of five years after a prescribed burn. In the closed forest, tree stem density declined markedly following the burn. Tree basal area and density decreased from 17.5 m2/ha and 630 trees/ha in the preburn sample to 12.0 m2/ha and 310 trees/ha five years later. In contrast, on the forest-prairie edge, tree basal area and density increased slightly during the same time period from 3.0 m2/ha and 117 trees/ha to 5.2 m2/ha and 172 trees/ha. Our data suggest that closed canopy forests in fire susceptible areas accumulate fuels to levels that encourage fires of sufficient intensity to destabilize forest systems and convert them to open forests or savannahs. Conversely, on the forest-prairie edge, amounts and patterns of fuel accumulation, and species response to burning, are such that fire can be considered to be a factor promoting stability.

Summary We examined mycorrhizal development in prairie cordgrass (Spartina pectinate Lind.), a mycorrhizal plant that typically occupies wet habitats, under different soil moisture conditions. The five experimentally induced soil moisture conditions ranged from continuous saturation to allowing soil moisture tensions to reach – 15 bars and then saturating the soil 48 h later. Colonization by vesicular-arbuscular mycorrhizal (VAM) fungi occurred under all experimental conditions but was significantly greater when plants were grown under conditions of 24 h saturation followed by 48 h of drainage than under any other moisture regime. There was a significant negative correlation between VAM fungal colonization and the weight of the rhizome-tiller units used to propogate experimental plants. Plant growth was not significantly affected by treatment conditions and there were no significant correlations between measured plant growth response and VAM colonization.

Purified proteoglycan subunits from human articular, bovine articular and nasal cartilages, and a rat chondrosarcoma were phosphorylated in vitro by beef heart cAMP-dependent protein kinase in the presence of gamma 32P-ATP. In these experiments, a maximum of 1.7 moles of 32P were incorporated per mole of proteoglycan from human cartilage. Phosphorylation was dependent on the presence of cAMP. Analysis by autoradiography revealed that serine residues in the core protein of the proteoglycan were the sites of phosphorylation. Treatment of proteoglycan subunits with chondroitinase ABC and alkaline phosphatase prior to reaction with cAMP-dependent protein kinase increased the incorporation of 32P by 12-30% when compared with untreated proteoglycans. These data indicate that proteoglycans in cartilage can be phosphorylated by cAMP-dependent protein kinase.