bluuebunny/crossref_metadata_2025 huggingface dataset:
The founding mothers: the genetic structure of newly established Daphnia populations
Authors: Louette Gerald , Vanoverbeke Joost , Ortells Raquel , De Meester Luc
Published: December 2007

Colonization dynamics may strongly influence within and among population genetic variation and evolutionary potential of populations. We here analyze the genetic structure during the first three years of 12 cyclical parthenogenetic Daphnia populations in newly created pond habitats. One to three genotypes were observed to colonize the populations, indicating a limited number of founders. Pronounced changes in genetic structure were associated with hatching of sexual dormant eggs after a period of absence of the newly founded populations from the active community. Despite rapid colonization, genetic differentiation among populations was fairly high with limited decay over time, suggesting long‐lasting founder effects. After initial colonization, no new alleles were observed in any of the populations, and our analyses suggests that this reflects reduced establishment success of later arrivals. Rare alleles increased in frequency, which likely is the result of inbreeding depression in selfed offspring of initially abundant clones, providing a fitness advantage to the sexual offspring of initially rare clones.
Dangerous dive cycles and the proverbial ostrich
Authors: Frid Alejandro , Heithaus Michael R. , Dill Lawrence M.
Published: December 2007

Data rarely are available to address the level of predation risk faced by diving animals in different parts of the water column. Consequently, most published research on diving behaviour implicitly assumes – like the proverbial ostrich – that ‘unseen’ predators are functionally unimportant. We argue that failure to consider diving in a predation risk framework may have precluded many insights into the ecology of aquatic foragers that breathe air. Using existing literature and a simple model, we suggest that fear from submerged predators in several systems might be influencing patch residence time, and therefore the duration of other dive cycle components. These analyses, along with an earlier model of predation risk faced by diving animals at the surface, suggest that dive cycle organisation can be modified to increase safety from predators, but only at the cost of reduced energy gain. Theoretical arguments presented here can seed hypotheses on factors contributing to population declines of diving species. For instance, adjustments to the dive cycle that reduce predation risk might be unaffordable if resources are scarce. Thus, if animals are to avoid imminent starvation or substantial loss of reproductive potential, resource declines might indirectly increase predation rates by limiting the extent to which dive cycles can deviate from those that would maximize energy gain. We hope that ideas presented in this paper stimulate other researchers to further develop theory and test predictions on how predation risk might influence diving behaviour and its ecological consequences.
Density‐dependent parameters and demographic equilibrium in open populations
Authors: Tavecchia Giacomo , Pradel Roger , Genovart Meritxell , Oro Daniel
Published: December 2007

Populations near their equilibrium are expected to show density‐dependence through a negative feedback on at least one demographic parameter, e.g. survival and/or productivity. Nevertheless, it is not always clear which vital rate is affected the most, and even less whether this dependence holds in open populations in which immigration and emigration are also important. We assessed the relative importance of population density in the variation of local survival, recruitment, proportion of transients (emigrants) and productivity through the analysis of detailed life‐histories of 4286 seabirds from a colony that reached an apparent demographic equilibrium after a period of exponential increase. We provide evidence that the role of population density and resource availability changes according to the demographic parameter considered. Estimates indicated that transients increased from 5% to 20% over the study period, suggesting an average turnover of about 1400 individuals per year. The parameters most influenced by population density alone were local survival and probability of transience. Recruitment was negatively associated with population density during the increasing phase but unexpected high values were also recorded at high population levels. These high values were explained by a combination of population size and food availability. Mean productivity varied with food availability, independently from population variations. The population density alone explained up to a third of the yearly variation of the vital rates considered, suggesting that open populations are equally influenced by stochastic and density‐independent events (such as environmental perturbations) than by intrinsic (i.e. density‐dependent) factors.
On nestedness analyses: rethinking matrix temperature and anti‐nestedness
Authors: Almeida‐Neto Mário , R. Guimarães Jr Paulo , M. Lewinsohn Thomas
Published: December 2007

The analysis of nested structures in sets of species assemblages across different sites or in networks of interspecific interactions has become common practice in ecological studies. Although new analyses and metrics have been proposed, few studies have scrutinized the concepts that subtend nestedness analysis. We note two important conceptual problems that can lead to terminological inconsistencies and flawed interpretations. First, the thermodynamic analogy that underlies the most common metric of nestedness, matrix temperature, is flawed and has led some authors to incorrect interpretations. Second, the term “anti‐nestedness” is a potential source of confusion and inconsistencies. We review four concepts for anti‐nestedness and examine how distinct they are. “Anti‐nested” matrices, i.e. less nested than expected by chance, may result from different ecological processes and show distinct structural patterns. Thus, there is no single unequivocal opposite of nestedness to be represented as “anti‐nestedness”. A more profitable approach is to designate and test each distinct non‐nested pattern according to its specific assumptions and mechanistic hypotheses.
Reproductive interference in two ground‐hopper species: testing hypotheses of coexistence in the field
Authors: Gröning Julia , Lücke Niklas , Finger Alexander , Hochkirch Axel
Published: December 2007

Similar to resource competition, reproductive interference may hamper the coexistence of closely related species. Species that utilize similar signal channels during mate finding may face substantial fitness costs when they come into contact and demographic displacement of the inferior species (sexual exclusion) is a likely outcome of such interactions. The two ground‐hopper species Tetrix ceperoi and Tetrix subulata broadly overlap in their ranges and general habitat requirements, but rarely co‐occur on a local scale. Results from laboratory and field experiments suggest that this mosaic pattern of sympatry might be influenced by reproductive interference. Here, we examine the significance of sexual interactions for these species in the field and test hypotheses on mechanisms of coexistence. Our results show that heterospecific sexual interactions also occur under field conditions, but in contrast to the experiments T. ceperoi was not the inferior species. The number of male mating attempts of both species was strongly correlated with encounter frequencies. Males discriminated between the sexes but not between the species, suggesting an incomplete mate recognition system in both species. The analysis of microhabitat preferences and spatial distribution revealed that habitat partitioning is not a suitable mechanism of coexistence in this system. Instead, the costs of reproductive interference are substantially mitigated by different niche breadths leading to different degrees of aggregation. Despite a considerable niche overlap T. ceperoi displayed a stronger preference for bare ground and occurred more aggregated than T. subulata, which had a broader niche. These differences may reduce the frequencies of heterospecific encounters and interactions in the field. Our results demonstrate that coexistence in the presence of reproductive interference is comparable to resource competition, being strongly influenced by ecological traits of the involved species, such as niche breadth and dispersion pattern.
Does the pattern of population synchrony through space reveal if the Moran effect is acting?
Authors: Abbott Karen C.
Published: December 2007

The populations of many species fluctuate in synchrony across large geographical areas. This synchrony is often attributed to the Moran effect, that is, shared environmental fluctuations across the region. In this article, I use a series of simple metapopulation models to show that the degree of synchrony among populations separated by different distances is strongly affected by the particular way that environmental stochasticity is represented in the models. Furthermore, when multiple types of stochasticity are acting simultaneously, the synchronizing effect of any one type is difficult to discern from the resulting pattern of population synchrony. These effects can be exacerbated under certain demographic conditions or if population dynamics are affected by interspecific interactions. In general, it should be extremely difficult to determine if synchrony is caused by the Moran effect using only the synchrony–distance relationship of natural populations.
Differences in pollinator faunas may generate geographic differences in floral morphology and integration inNarcissus papyraceus(Amaryllidaceae)
Authors: Pérez‐Barrales Rocío , Arroyo Juan , Scott Armbruster W.
Published: December 2007

Pollinators may generate selective pressures that affect covariation patterns of multiple traits as well as the mean values of single floral morphological traits. Berg predicted that flowers pollinated by animals whose morphology closely matches the flower's shape will be phenotypically more integrated (tighter correlation of flower traits) than will flowers pollinated by animals not closely fitting the floral morphology. We tested this hypothesis by comparing, in the Strait of Gibraltar region (south Spain, northern Morocco), populations ofNarcissus papyraceusthat have geographical differences in pollinator faunas. Long‐tongued, nectar‐feeding moths dominate the pollinator faunas of those populations close to the Strait of Gibraltar, whereas short‐tongued, pollen‐feeding syrphid flies dominate in peripheral populations farther from the Strait. Populations pollinated by moths and flies differed in the mean values of several floral traits, consistent with the evolution of regional pollination ecotypes. Populations pollinated by moths showed stronger intercorrelation (floral integration) than populations pollinated by hoverflies. Moth‐pollinated populations also showed less variation in flower traits than vegetative traits, and this difference was stronger than in fly‐pollinated populations. Thus, the pattern of differences in the phenotypic architecture of theNarcissusflowers is consistent with the hypothesis that populations have responded to different selective pressures generated by different pollinators. These data also supported most of the specific predictions of Berg's hypotheses about integration and modularity.
Comparative genetic structure reflects underlying life histories of three sympatric small mammal species in continuous forest of south‐eastern Australia
Authors: Kraaijeveld‐Smit F. J. L. , Lindenmayer D. B. , Taylor A. C. , MacGregor C. , Wertheim B.
Published: December 2007

There are strong links between habitat fragmentation, population size and genetic structure. However, to fully understand the long‐term effects of fragmentation on population viability, it is necessary to first understand the relationship between life history traits and genetic characteristics in un‐fragmented habitats. This is best done through comparing patterns of genetic diversity in sympatric species, since relative data may be maximally informative. We compared genetic structure and diversity among three sympatric small mammals – of which two were marsupial species – over a small spatial scale (<4 km) using microsatellite genotypic data from individuals sampled from four grids spaced in a linear fashion. Expected heterozygosity was high for all three species (average He range: 0.781–0.886), but the smallest species had significantly higher genetic diversity (both heterozygosity and allelic diversity) than the two larger species, possibly due to it having; 1) large effective population size and little overlap in generations, and/or 2) high mutation rates in large alleles. Genotypic isolation by distance (measured as relatedness) was detected only at the smallest distance of 750 m, for any species. In the two marsupial species Fst, relatedness and percentage of individuals assigned to site of capture were significantly lower in males than in females, corroborating previous reports of male‐biased dispersal. However, sex‐biased dispersal was not detected for the third species (the native bush rat Rattus fuscipes), and presence of significant heterozygous deficits suggested this resulted in inbreeding within kin‐structured demes. We speculate that habitat fragmentation will have differing effects on population dynamics, social organisation and mating systems for the two marsupial species compared to the native murid rodent, due to their differing population structure and divergent inbreeding avoidance mechanisms.
The need for pluralism in landscape models: a reply to Dunn and Majer
Authors: Lindenmayer David B. , Fischer Joern , Hobbs Richard
Published: December 2007

Dunn and Majer discuss limitations of the continuum model proposed by Fischer and Lindenmayer and describe a new patch‐based model. We argue that a range of landscape models are required to solve different problems and meet particular objectives of land management or conservation. The key issue is not whether one type of model is superior to another, but rather: what are the particular strengths and limitations of a particular model? And, given these, under what circumstances will a particular model be most appropriate? The primary value of the continuum model is that it provides a strong theoretical foundation for the management of landscape heterogeneity in addition to the protection of large patches of native vegetation.
Optimizing protein intake as a foraging strategy to maximize mass gain in an omnivore
Authors: Robbins Charles T. , Fortin Jennifer K. , Rode Karyn D. , Farley Sean D. , Shipley Lisa A. , Felicetti Laura A.
Published: December 2007

Energy maximization, time minimization, and linear programming models subject to various constraints have dominated foraging ecology ideas and methods for decades. However, animals must use very complex physiological processes and foraging decisions to ensure fitness that in many cases may not be adequately described by these approaches. An example of this problem occurs when brown bears, Ursus arctos, have access to both abundant salmon and fruit. Salmon are one of the most energy and nutrient dense foods available to bears. Fruits are often high in soluble carbohydrates, low to deficient in many required nutrients, and more difficult to efficiently exploit. Therefore, wild brown bears that fatten primarily on fruits without access to salmon are 50% smaller than salmon‐feeding bears. Thus, we predicted based on a linear, energy‐maximizing model without dietary interaction effects that wild brown bears with access to both abundant salmon and fruit would feed almost exclusively on salmon. However, wild adult females with or without accompanying offspring foraged three times longer per day on fruit than on salmon. Similarly, the relative dry matter intake of ad libitum apples and salmon by captive, adult brown bears averaged 76±5% fruit and 24±5% salmon. Captive brown bears consuming mixed diets with intermediate dietary protein levels had 60% lower maintenance energy costs, 37% to 139% higher efficiencies of mass gain, and 72% to 520% higher maximum rates of gain than when they consumed either salmon or fruit alone. These relationships were nonlinear functions of dietary protein content in which salmon and fruit provided complementary nutritional resources. Both wild and captive bears attempted to regulate total protein, energy, and carbohydrate intake within a multidimensional intake target that both maximized energy intake and mass gain.
Some bold evolutionary predictions for the future of mating in humans
Authors: Aarssen Lonnie W.
Published: December 2007

Why are many human populations presently ‘imploding’ with below‐replacement fertility? Why are more and more young adults in these societies choosing to remain single and/or childless? Based on first principles of evolutionary theory, predictions can be derived for changes over time in the relative frequency distributions of four traits in humans proposed as the most direct determinants of the propensity to mate and reproduce: attractions to sex, legacy, leisure and parenting. In the past, high fitness was most profoundly determined by strong sex drive and strong legacy drive, especially in males. Female fertility was largely controlled by dominant males, who were then free to engage in attractions to both leisure and legacy through ‘memes’ (as well as through genes, or offspring) without any penalty on fitness. Natural selection in the past, therefore, neither strongly favoured nor strongly disfavoured any particular intrinsic female inclinations or preferences that might affect offspring production. The recent, widespread, and continuing rise in the empowerment of women, however, defines a dramatically different contemporary selection regime, where women are now free to indulge in their evolved attractions to leisure and legacy through memes inherited from predecessors, both of which represent compelling distractions from parenthood. The implications for the future survival of marriage and parenthood as cultural institutions look dismal in the short term, but promising in the long term.
Genetic structure of the diploid–polyploid fish Squalius alburnoides in southern Iberian basins Tejo and Guadiana, based on microsatellites
Authors: Crespo‐López M. E. , Pala I. , Duarte T. L. , Dowling T. E. , Coelho M. M.
Published: December 2007

Several studies have demonstrated the hybrid origin of Squalius alburnoides, a complex of diploid, triploid and tetraploid fish, with Squalius pyrenaicus as the maternal ancestor and an Anaecypris hispanica‐like species as the paternal ancestor. The aim of this study was to assess patterns of genetic diversity and similarity between sympatric forms of the different ploidy levels of S. alburnoides and related parental species in the two largest basins that are part of its southern Iberian distribution, the Tejo and Guadiana, using microsatellites. High levels of genetic diversity were found in populations of S. alburnoides from both basins, reflecting the hybrid origin, the high diversity of forms in these river basins and the different modes of reproduction of the complex. Microsatellites indicated low values of genetic differentiation between the non‐hybrid all‐male form of S. alburnoides and A. hispanica, supporting the view that these forms share a common ancestor. In some instances, diploid and triploid hybrids from the same river basin were more closely related to each other than to their counterparts in the other basins, suggesting an ancient origin for the complex in these Iberian southern basins.
A quantitative link between globular clusters and the stellar haloes in elliptical galaxies
Authors: Forte Juan C. , Faifer Favio , Geisler Doug
Published: December 2007

This paper explores the quantitative connection between globular clusters and the ‘diffuse’ stellar population of the galaxies they are associated with. Both NGC 1399 and NGC 4486 (M87) are well suited for this kind of analysis due to their large globular cluster populations.

The main assumption of our Monte Carlo based models is that each globular cluster is formed along with a given diffuse stellar mass that shares the same spatial distribution, chemical composition and age. The main globular cluster subpopulations, that determine the observed bimodal colour distribution, are decomposed avoiding a priori parametric (e.g. Gaussian) fits and using a new colour (C−T1)–metallicity relation. The eventual detectability of a ‘blue’ tilt in the colour–magnitude diagrams of the blue globular cluster subpopulation is also addressed.

A successful link between globular clusters and the stellar galaxy halo is established by assuming that the number of globular clusters per associated diffuse stellar mass t is a function of total abundance [Z/H] and behaves as t=γ exp(−δ[Z/H]) (i.e. increases when abundance decreases).

The simulations allow the prediction of a surface brightness profile for each galaxy through these two free parameters' approximation. The γ, δ parameters that provide the best fit to the observed profiles in the B band, in turn, determine several features, namely, large-scale halo colour gradients, globular cluster–halo colour offset, clusters' cumulative specific frequencies, and stellar metallicity distributions, that compare well with observations.

The results suggest the co-existence of two distinct stellar populations characterized by widely different metallicities and spatial distributions. One of these populations (connected with the blue globular clusters) is metal poor, highly homogeneous, exhibits an extended spatial distribution and becomes more evident at large galactocentric radius contributing with some 20 per cent of the total stellar mass. In turn, the stellar population associated with the red globular clusters is extremely heterogeneous and dominates the inner region of both galaxies.

Remarkably, and although the cluster populations of these galaxies exhibit detectable differences in colour distribution, the δ parameter that determines the shape of the brightness profiles of both galaxies has the same value, δ≈ 1.1 to 1.2 ± 0.1.
Continuous Innovation and Performance Management of SME Clusters
Authors: Carpinetti Luiz Cesar Ribeiro , Gerolamo Mateus Cecilio , Galdámez Edwin Vladimir Cardoza
Published: December 2007

Continuous innovation and performance measurement methods and tools have been applied in companies as a means to develop improvement actions related to strategic objectives and to monitor results so as to give feedback for further action. However, continuous innovation and performance measurement methods and tools can also be applied to manage performance of a cluster of firms. After a brief review of continuous innovation and the concept of collective efficiency of a cluster, this paper presents a conceptual model for managing actions for improving collective efficiency and measuring performance of an SME cluster. A research case is reported, for which the conceptual model has been applied and results discussed. The paper concludes that despite some difficulties in developing and using performance indicators in SMEs, the concepts presented by the proposed model can help to foster cooperation and maturity in continuous innovation in clusters of SMEs.
Exploring Differences between Inventors, Champions, Implementers and Innovators in Creating and Developing New Products in Large, Mature Firms
Authors: Sim Edward W. , Griffin Abbie , Price Raymond L. , Vojak Bruce A.
Published: December 2007

This exploratory research investigates nine individuals participating as specialists in different phases of the invention and new product development (NPD) process in one organization. In‐depth interviews were conducted with these individuals, as well as with 17 of their managers and co‐workers, adding an external perspective about them. These nine individuals participated in four different divisions of labour in the innovation process: inventors who focus on scientific and technical invention prior to concept development, champions who are most adept at selling acceptance of projects into the organization, implementers who focus on facilitating the project through the firm's formal development process, and innovators who operate across all three phases of invention, acceptance and implementation. The research finds differences in personality, perspective, knowledge base, motivation, and attitude toward politics that seem to be associated with these different specialist types. These differences lead to implications for the types of projects for which they might best be suited, as well as for how they might best be managed.
REVISING THE PAST / REVISITING THE PRESENT: HOW CHANGE HAPPENS IN HISTORIOGRAPHY
Authors: SPIEGEL GABRIELLE M.
Published: December 2007

This article investigates the various forces that may help to explain the ongoing historio‐graphical phenomenon of revision. It takes as its point of departure Michel de Certeau's understanding of the writing of history as a process consisting of an unstable and constantly changing triangulated relationship among a place (a recruitment, a milieu, a profession), analytical procedures (a discipline), and the construction of a text (or discourse). For de Certeau, revision is the formal prerequisite for writing history because the very distance between past and present requires continuous innovation simply to produce the objects of historical knowledge, which have no existence apart from the historian's identification of them. The specific nature of revision at a given moment is determined by the specificities of the process as a whole, that is, by the characteristics of place, procedure, and text and their contemporary relational configuration.

Taking the rise of “linguistic‐turn” historiography as exemplary of the process of historical revision in its broadest possible meaning, the article seeks to discover the possible “causes” for that turn. It begins with an analysis of the psychological roots of poststructuralism as a response to the holocaust and its aftermath, and then proceeds to explore the possible economic and social transformations in the postwar world that might account for its reception, both in Europe but also, more counterintuitively, in the United States, where postmodernism proved to have an especially strong appeal. Added to this mix are the new patterns of social recruitment into the historical profession in the “sixties.” the essay suggests that, to the extent that revision is understood as the result of the combined effect of psychological, social, and professional determinations, it is unlikely that there will ever be genuine consensus about the sources of revision in history, since all historians bring to their work differing congeries of psychological preoccupations, social positions, and professional commitments.
Effect of narghile and cigarette smoking on newborn birthweight
Authors: Tamim H , Yunis KA , Chemaitelly H , Alameh M , Nassar AH ,   National Collaborative Perinatal Neonatal Network Beirut, Lebanon
Published: December 2007

Objective  To assess the effect of narghile smoking on the weight of newborns.

Design  Historical retrospective cohort.

Setting  Six major hospitals in Greater Beirut, Lebanon.

Population  Consecutive singleton newborns delivered from August 2000 to August 2003.

Methods  Obstetric and nursery charts were reviewed to obtain information about maternal and neonatal variables. Information concerning initiation of smoking, dose of smoking, smoking habits during pregnancy, and socio‐demographic characteristics was collected through interviews with mothers.

Main outcome measures  Low birthweight and newborn birthweight.

Results  Exclusive narghile smokers constituted 4.4% (378/8592) of women. Multiparas were significantly more likely to smoke cigarettes and narghile. Mothers smoking narghile more than once per day were at 2.4 increased odds of having low birthweight infants compared with nonsmoking mothers (OR 2.4; 95% CI 1.2–5.0) after adjusting for confounding variables. No difference was noted between women smoking narghile in the first trimester and those initiating smoking in subsequent trimesters regarding low birthweight.

Conclusions  Narghile smoking more than once per day increases the odds of low birthweight by a 2.4‐fold compared with nonsmokers, although to a lesser extent than cigarette smoking.
Manual versus electric vacuum aspiration for first‐trimester abortion: a systematic review
Authors: Wen J , Cai QY , Deng F , Li YP
Published: December 2007

Background  As an alternative to electric vacuum aspirations (EVA), there is an increasing interest in using manual vacuum aspiration (MVA).

Objective  To compare the safety, efficacy and acceptability of MVA with those of EVA for first‐trimester abortion.

Search strategy  We searched MEDLINE, EMBASE, Cochrane Library and Chinese Biomedical Database in all language, together with reference lists of retrieved papers.

Selection criteria  Randomised controlled trials comparing MVA with EVA for first‐trimester abortion were included. The outcomes are complete abortion rate, uterine perforation rate, blood loss, pain perception and acceptability.

Data collection and analysis  Two reviewers independently extracted the data. Results from the trials were combined to calculate relative risks (RRs) or risk differences for dichotomous outcomes and weighted mean differences (WMDs) for continuous outcomes, together with 95% CIs.

Main results  Ten trials were included, involving 1660 women. Generally, the methodological quality was poor. There were no statistically significant differences, comparing MVA with EVA, in complete abortion rate (RR 1.00; 95% CI 0.99–1.02) and participants’ satisfaction (RR 1.02; 95% CI 0.87–1.20). In participants with less than 50 days of gestational age, less blood loss (WMD −1.84; 95% CI −2.45 to −1.23) and less severe pain perception (RR 0.04; 95% CI 0.01–0.12) were reported during the MVA procedure, whereas the operation time was shorter (WMD 0.32; 95% CI 0.02–0.63) in the EVA procedure.

Author’s conclusions  There is some evidence that MVA is as effective and acceptable as EVA and might be safer than EVA.
Unique Aspects of Adolescent Sexual Victimization Experiences
Authors: Livingston Jennifer A. , Hequembourg Amy , Testa Maria , VanZile-Tamsen Carol
Published: December 2007

This study explored females’ adolescent experiences with sexual aggression using event-level data. A community sample of women, ages 18 to 30 years ( N = 319), were interviewed regarding their most recent unwanted sexual experience. Incidents were categorized as occurring during adolescence (ages 14 to 17) or adulthood (after age 18). Preliminary statistical comparison of adolescent and adult incidents revealed differences in perpetrators, type of aggression, preceding activities, and location of assault. Qualitative analytic techniques were then used to identify the contexts in which adolescent victimization occurred, as well as the factors contributing to adolescent vulnerability. Four contexts in which adolescents were sexually victimized emerged: Within Intimate Relationships, At Parties/Social Gatherings, Abuse by Authority Figures, and While Alone With a Friend. Thematic analysis revealed that inexperience with sex and dating, lack of guardianship, substance use, social and relationship concerns, and powerlessness contributed to adolescent vulnerability within these contexts.
‘We’re here to stay’: economic restructuring, Latino migration and place‐making in the US South
Authors: Smith Barbara Ellen , Winders Jamie
Published: December 2007

This article examines immigrants’ and long‐term residents’ intertwining practices of flexible labour and social reproduction in the American South. It analyses neoliberal globalisation's flexible‐labour demands through the body and social reproduction's spatial forms and politics through place, arguing for the centrality of these processes to both recent political shifts in the South and broader theorisations of globalisation and social reproduction. As immigrants and long‐term southern residents grapple with factors from casualised employment to militarised borders, they work to situate themselves in place as community members. The frictions between these processes create political initiatives into which our analysis offers new insight.
A Comparative Study of Quality Outcomes in Freestanding Ambulatory Surgery Centers and Hospital‐Based Outpatient Departments: 1997–2004
Authors: Chukmaitov Askar S. , Menachemi Nir , Brown L. Steven , Saunders Charles , Brooks Robert G.
Published: December 2007

Research Objective. To compare quality outcomes from surgical procedures performed at freestanding ambulatory surgery centers (ASCs) and hospital‐based outpatient departments (HOPDs).

Data Sources. Patient‐level ambulatory surgery (1997–2004), hospital discharge (1997–2004), and vital statistics data (1997–2004) for the state of Florida were assembled and analyzed.

Study Design. We used a pooled, cross‐sectional design. Logistic regressions with time fixed‐effects were estimated separately for the 12 most common ambulatory surgical procedures. Our quality outcomes were risk‐adjusted 7‐day and 30‐day mortality and 7‐day and 30‐day unexpected hospitalizations. Risk‐adjustment for patient demographic characteristics and severity of illness were calculated using the DCG/HCC methodology adjusting for primary diagnosis only and separately for all available diagnoses.

Principal Findings. Although neither ASCs nor HOPDs performed better overall, we found some difference by procedure that varied based on the risk‐adjustment approach used.

Conclusions. There appear to be important variations in quality outcomes for certain procedures, which may be related to differences in organizational structure, processes, and strategies between ASCs and HOPDs. The study also confirms the importance of risk‐adjustment for comorbidities when using administrative data, particularly for procedures that are sensitive to differences in severity.
Accommodative esotropia following surgical treatment of infantile esotropia: frequency and risk factors
Authors: Uretmen Onder , Civan Baturhan B. , Kose Suheyla , Yuce Berna , Egrilmez Sait
Published: December 2007

Purpose:  We aimed to examine the frequency of and risk factors for the development of accommodative esotropia following surgical treatment for infantile esotropia.

Methods:  A total of 29 children were recruited. Potential risk factors for the development of accommodative esotropia included: sex; angle of deviation at initial and final visits; cycloplegic refractive error at initial and final visits; increase in hyperopia; amblyopia; amblyopia treatment; age at surgical treatment; pre‐ and postoperative latent nystagmus; dissociated vertical deviation or inferior oblique muscle overaction; additional surgical procedures; unstable alignment, and binocular sensory status.

Results:  Overall, 14 (48.2%) of 29 children developed accommodative esotropia during the 36‐ to 132‐month postoperative follow‐up period. Twelve (85.7%) of the 14 patients developed refractive accommodative esotropia and two developed non‐refractive accommodative esotropia. The onset of accommodative esotropia occurred at a mean of 8.8 months (range 6–24 months) after the initial surgical alignment. This corresponded to a mean age of onset for accommodative esotropia of 43.2 months. We determined that, among children with infantile esotropia, those who had hyperopia of ≥ 3.0 D and increasing hyperopia after surgery and those who did not develop dissociated vertical deviation during the follow‐up period were more likely to develop accommodative esotropia.

Conclusions:  Children who have the established risk factors should be followed closely for the development of accommodative esotropia. The treatment of these children with appropriate glasses may prevent the development of adverse effects of accommodative esotropia on sensory and motor functions.
Development of the Bronze Age landscape in the southeastern Arabian Gulf: new evidence from a buried shell midden in the eastern extremity of the Rub’ al‐Khali desert, Emirate of Ras al‐Khaimah, U.A.E.
Authors: Parker A. G. , Goudie A. S.
Published: December 2007

Recent sand quarrying operations for building and construction work in the eastern extremity of the Rub’ al‐Khali sand sea has revealed sediment exposures through a number of coastal and inland dunes. In the al‐Daith district of Ras al‐Khaimah (U.A.E.) a Holocene shell midden was exposed 2.8 m below the present dune surface interstratified between phases of Late Pleistocene and late Holocene dune sands. C14 and OSL ages constrain the site giving an insight into phases of landscape instability, dune formation, rates of sediment accretion, and a period of stability and human occupation. To date, Hafit period sites (5200–4500 cal BP) have been recorded in large numbers in the mountains and gravel plains of the Oman mountains. Coastal shell middens have not, as yet, been ascribed to the Hafit period from this part of the region and the study presents the first radiocarbon age from such a site. This study indicates the potential that many other sites exist elsewhere buried under late Holocene dune sediments and these provide an important insight into the development of the coastal landscape of this region.
Multivariate study of factors influencing primary dental implant stability
Authors: Mesa Francisco , Muñoz Ricardo , Noguerol Blas , Luna Juan de Dios , Galindo Pablo , O'Valle Francisco
Published: December 2007

Objectives: The purpose was to determine by multivariate analysis in a large series of dental implants the variables associated with primary endosseous dental implant stability (DIS).

Material and methods: A 10‐year retrospective study was conducted of 1084 Brånemark® implants placed in 316 patients. Clinical variables (age, gender, smoking habit, and periodontal status), implant diameter, implant length, and Periotest® values (PTVs) were analyzed in bivariate and multivariate studies in order to determine their influence on DIS, using a cut‐off PTV value of −2.

Results: The site of implant insertion showed the strongest association with primary DIS failure among the study variables. Implants in the anterior mandible had a 6.43‐fold lower risk of primary DIS risk vs. those at other sites [95% confidence interval (CI) 3.28–12.61], and implants in the maxillary had a 2.70‐fold higher risk of primary DIS failure vs. those in the mandible (95% CI 1.82–4). Among other variables, females had a 1.54‐fold higher risk of primary DIS failure vs. males (95% CI 1.88–2.22) and implants <15 mm in length had a 1.49‐fold higher risk of failure vs. longer implants (95% CI 1.09–2.04).

Conclusion: According to these findings, primary DIS failure is more likely in females, at sites other than the anterior mandible, and with dental implants shorter than 15 mm, at least when non‐threaded titanium implants are used. These data may be of value in the identification of patients at a high risk of primary DIS failure with immediate implant loading.
Benefits of hormone replacement therapy in postmenopausal women
Authors: Canderelli Richard , Leccesse Lisa A. , Miller Nancy L. , Unruh Davidson Janice
Published: December 2007

Purpose: To provide an overview of current research regarding hormone replacement therapy (HRT) and to assist healthcare providers to better educate patients about potential benefits of this therapy.

Data sources: A systematic review of healthcare literature was conducted with 602 articles selected from CINAHL, Medscape, Pubmed, and Medline databases. Keywords directing the search included hormone replacement therapy, benefits of hormone replacement therapy and trends, hormone replacement therapy and osteoporosis, hormone replacement, and menopause symptoms.

Conclusions: According to the literature, HRT can assist women with postmenopausal symptoms. In addition, research shows that HRT can help some postmenopausal women with selected comorbid conditions such as osteoporosis, type II diabetes, certain cardiovascular pathologies, and colorectal cancer. The decision as to who should use any form of HRT needs to be based on the individual woman’s needs, quality of life, and potential risks versus benefits.

Implications for practice: HRT has been a benefit to many women in the treatment of postmenopausal symptoms. Recent studies have shown that HRT, whether it is combined estrogen and progestin therapy, or estrogen‐only therapy, can help postmenopausal women with osteoporosis and some selected comorbid conditions. Recent research indicates that some women are dying from comorbid conditions rather than breast cancer. Although the research regarding HRT in some areas may be limited, further research adds to existing knowledge and offers new ideas and possibilities in the treatment of postmenopausal symptoms and selected comorbid conditions. Certainly HRT can improve quality of life and possibly longevity for selected women. Ongoing research is needed to further validate such benefits, as well as to further explore the risks and benefits of long‐term HRT. Increased knowledge about HRT will help healthcare providers better educate patients about the potential benefits of HRT, while providing documentation about who should take selected types of HRT or whether alternative treatment is preferred.
Automatic multiscale enhancement and segmentation of pulmonary vessels in CT pulmonary angiography images for CAD applications
Authors: Zhou Chuan , Chan Heang‐Ping , Sahiner Berkman , Hadjiiski Lubomir M. , Chughtai Aamer , Patel Smita , Wei Jun , Ge Jun , Cascade Philip N. , Kazerooni Ella A.
Published: December 2007

The authors are developing a computerized pulmonary vessel segmentation method for a computer‐aided pulmonary embolism (PE) detection system on computed tomographic pulmonary angiography (CTPA) images. Because PE only occurs inside pulmonary arteries, an automatic and accurate segmentation of the pulmonary vessels in 3D CTPA images is an essential step for the PE CAD system. To segment the pulmonary vessels within the lung, the lung regions are first extracted using expectation‐maximization (EM) analysis and morphological operations. The authors developed a 3D multiscale filtering technique to enhance the pulmonary vascular structures based on the analysis of eigenvalues of the Hessian matrix at multiple scales. A new response function of the filter was designed to enhance all vascular structures including the vessel bifurcations and suppress nonvessel structures such as the lymphoid tissues surrounding the vessels. An EM estimation is then used to segment the vascular structures by extracting the high response voxels at each scale. The vessel tree is finally reconstructed by integrating the segmented vessels at all scales based on a “connected component” analysis. Two CTPA cases containing PEs were used to evaluate the performance of the system. One of these two cases also contained pleural effusion disease. Two experienced thoracic radiologists provided the gold standard of pulmonary vessels including both arteries and veins by manually tracking the arterial tree and marking the center of the vessels using a computer graphical user interface. The accuracy of vessel tree segmentation was evaluated by the percentage of the “gold standard” vessel center points overlapping with the segmented vessels. The results show that (2398/2494) and (1910/1984) of the manually marked center points in the arteries overlapped with segmented vessels for the case without and with other lung diseases. For the manually marked center points in all vessels including arteries and veins, the segmentation accuracy are (4546/4689) and (4439/4732) for the cases without and with other lung diseases, respectively. Because of the lack of ground truth for the vessels, in addition to quantitative evaluation of the vessel segmentation performance, visual inspection was conducted to evaluate the segmentation. The results demonstrate that vessel segmentation using our method can extract the pulmonary vessels accurately and is not degraded by PE occlusion to the vessels in these test cases.
Choice of data types in time resolved fluorescence enhanced diffuse optical tomography
Authors: Riley Jason , Hassan Moinuddin , Chernomordik Victor , Gandjbakhche Amir
Published: December 2007

In this paper we examine possible data types for time resolved fluorescence enhanced diffuse optical tomography (FDOT). FDOT is a particular case of diffuse optical tomography, where our goal is to analyze fluorophores deeply embedded in a turbid medium. We focus on the relative robustness of the different sets of data types to noise. We use an analytical model to generate the expected temporal point spread function (TPSF) and generate the data types from this. Varying levels of noise are applied to the TPSF before generating the data types. We show that local data types are more robust to noise than global data types, and should provide enhanced information to the inverse problem. We go on to show that with a simple reconstruction algorithm, depth and lifetime (the parameters of interest) of the fluorophore are better reconstructed using the local data types. Further we show that the relationship between depth and lifetime is better preserved for the local data types, suggesting they are in some way not only more robust, but also self‐regularizing. We conclude that while the local data types may be more expensive to generate in the general case, they do offer clear advantages over the standard global data types.
Performance of a direct‐detection active matrix flat panel dosimeter (AMFPD) for IMRT measurements
Authors: Chen Yu , Moran Jean M. , Roberts Donald A. , El‐Mohri Youcef , Antonuk Larry E. , Fraass Benedick A.
Published: December 2007

The dosimetric performance of a direct‐detection active matrix flat panel dosimeter (AMFPD) is reported for intensity modulated radiation therapy (IMRT) measurements. The AMFPD consists of photodiodes and thin‐film transistors deposited on a glass substrate with no overlying scintillator screen or metal plate. The device is operated at 0.8 frames per second in a continuous acquisition or fluoroscopic mode. The effect of the applied bias voltage across the photodiodes on the response of the AMFPD was evaluated because this parameter affects dark signal, lag contributions, and pixel sensitivity. In addition, the AMPFD response was evaluated as a function of dose, dose rate, and energy, for static fields at 10 cm depth. In continuous acquisition mode, the AMFPD maintained a linear dose response up to at least 1040 cGy. In order to obtain reliable integrated dose results for IMRT fields, the effects of lag on the radiation signal were minimized by operating the system at the highest frame rate and at an appropriate reverse bias voltage. Segmental MLC and dynamic MLC IMRT fields were measured with the AMFPD, and the results were compared to film, using standard methods for reliable film dosimetry. Both AMFPD and film measurements were independently converted to dose in cGy. and values were calculated as indices of agreement. The results from the AMFPD were in excellent agreement with those from film. When of and 2 mm of distance to agreement were used as the criteria, of the region of interest (defined as the region where dose is greater than of ) satisfied on average across the cases that were tested.
Magnetism in Medicine: A handbook, Second Completely Revised and Enlarged Edition
Authors: Zhou Xiaohong Joe
Published: December 2007

Magnetism in Medicine: A handbook, Second Completely Revised and Enlarged Edition Andrä Wilfried Nowak Hannes Wiley‐VCH, Berlin, 2006. 629 pp. $210.00 ISBN 9783527405589.
Comment on "Synthesis of Ultra-Incompressible Superhard Rhenium Diboride at Ambient Pressure"
Authors: Dubrovinskaia Natalia , Dubrovinsky Leonid , Solozhenko Vladimir L.
Published: December 2007

Chung
et al
. (Reports, 20 April 2007, p. 436) reported the synthesis of superhard rhenium diboride (ReB
2
) at ambient pressure. We show that ReB
2
, first synthesized at ambient pressure 45 years ago, is not a superhard material. Together with the high cost of Re, this makes the prospect for large-scale industrial applications of ReB
2
doubtful.