Strengths Of Barriers Research Articles

Mapping the Barriers of Utilizing Public Private Partnership into Brownfield Remediation Projects in the Public Land Ownership

The financing issue is increasingly becoming a key problem for brownfield remediation in public land ownership, and Public Private Partnership (PPP) mode is considered a potentially effective solution. However, some barriers impede the utilization of the PPP mode into brownfield remediation projects in the situation of public land ownership. By taking China as an example, the study investigates the barriers when the PPP mode is used in brownfield remediation projects to deal with financing dilemmas. Specifically, 39 original barriers are first obtained from existing related literature. Based on these original barriers, a semi-structured questionnaire is designed and used in a Delphi process to achieve 14 final barriers, which can reflect the particular situation in China. To identify the interrelationship among these barriers, Interpretative Structural Modeling (ISM) is used to map the hierarchical structure of the final barriers, and the Cross-Impact Matrix Multiplication Applied to Classification (MICMAC) analysis is applied to show the relationship strengths of barriers. According to the results of the ISM and MICMAC analyses, three key barriers are determined, and several corresponding recommendations are provided from the perspective of the public administration.

A Qualitative Study Assessing Haitian Pediatric Nursing Educational Needs in Port-au-Prince, Haiti.

After Port-au-Prince's 2010 earthquake, Hospital Bernard Mevs (HBM) developed a collaboration with international medical volunteers to provide clinical care and medical resources; that evolved to include medical education as local Haitian staffing developed. There has been limited coordination among volunteers and local providers about ways in which volunteers can best serve the hospital, and literature that addresses how to coordinate volunteer efforts to support the educational needs of the local nursing staff is scant. Our objectives were to complete an educational needs assessment of the most common diagnoses encountered, requested topics for education, and preferred learning modalities as reported by Haitian pediatric nurses, and categorize the strengths of HBM and barriers to care to understand more fully the context within which nurses function, and how education and international volunteers may be related. In October 2019, 10 HBM pediatric nurses participated in small-group interviews. Questions were based on an interview guide and responses were coded and analyzed for recurring themes. The most common diagnoses were sepsis, hydrocephalus, and hypoxic ischemic encephalopathy. Topics for review included chest tubes, ventilator management, and ventriculoperitoneal shunts. Preferred learning modalities were didactics and hands-on workshops. Strengths of the hospital were team dynamics and education provided by HBM and international volunteers, whereas the most common barrier to care was lack of clinical supplies. This information is useful to guide future educational interventions, and this model may inform other programs with a volunteer presence in resource-limited settings to promote collaboration and self-directed learning.

Does reproductive isolation reflect the segregation of color forms in Spiranthes sinensis (Pers.) Ames complex (Orchidaceae) in the Chinese Himalayas?

Isolation between species, or taxa sharing a common lineage, depends primarily on the relative strengths of various reproductive barriers. Previous studies on reproductive isolation between orchids emphasized mechanical and ethological barriers in flowers of species showing food and/or sexual mimicry. In this study, we investigated and quantified a series of prepollination and postpollination barriers between pink and white forms of Spiranthes sinensis sl, a nectar‐secreting complex. We generated ML trees based on trnS‐G and matK to explore phylogenetic relationships in this species complex. Spiranthes sinensis sl segregated from some other congeners, but the white form constituted a distinct clade in relation to the pink form. The white form secreted 2‐Phenylethanol as it is a single‐scent compound and was pollinated almost exclusively by native, large‐bodied Apis cerana and Bombus species (Apidae). Apis cerana showed a high floral constancy to this form. The scentless, pink form was pollinated primarily by smaller bees in the genera Ceratina (Apidae), and members of the family Halictidae, with infrequent visits by A. cerana and Bombus species. Fruit set and the production of large embryos following interform pollination treatments were significantly lower compared to intraform pollination results for the white form. Our results suggested that pollinator isolation, based on color and scent cues, may result in greater floral constancy in white populations when both forms are sympatric as two different, guilds of pollinators forage selectively preventing or reducing prospective gene flow. Postpollination barriers appear weaker than prepollination barriers but they also play a role in interform isolation, especially in the white form. Our findings suggest that floral color forms in S. sinensis do not represent an unbalanced polymorphism. Interpretations of the evolutionary status of these forms are discussed.

Quantification of the zygotic barrier between interbreeding taxa using gene flow data

Hybridization and introgression via interspecific gene flow are common processes in the plant kingdom. The effectiveness of these processes is governed by the strengths of multiple zygotic barriers. These barriers have often been quantified in artificial settings using laborious and time‐consuming hand‐pollination experiments, but their quantification is nonexistent in the landscape. In this study, we utilized gene flow data within a spatially explicit simulation to assess the strengths of zygotic barriers. Our model system consisted of Populus nigra and its hybrid, P. × canadensis, which interbreed under natural conditions. The study population was located in the floodplain of the Eder River in central Germany. Pollen‐mediated introgression rates from hybrid males into the seeds of individual female trees were used as the target pattern using an inverse modeling approach. Simulations that treated pollen from both taxa equally revealed a large discrepancy between the observed and modeled rates of introgression for both taxa. The discrepancy was reduced by introducing a zygotic barrier against the pollen from the hybrid males. The best model outcome values indicated comparably strong zygotic barriers acting against pollen‐mediated introgressive gene flow into the two parental taxa, P. nigra and P. × canadensis. The sensitivity of our model was tested by applying different dispersal functions. Four common probability density functions were used along with a pollen dispersal function that had previously been fitted to gene flow data from the same dataset. The best barrier value was almost independent of the dispersal functions used here. Moreover, it was within the range previously determined in hand‐pollination‐based investigations, validating our model. These data indicate that the inverse modeling approach is a powerful method for quantifying hidden processes, and we discuss its use as a valuable tool for generating new insights into plant mating systems that are relevant to evolutionary biology and risk analyses in conservation efforts.

Long-term persisting hybrid swarm and geographic difference in hybridization pattern: genetic consequences of secondary contact between two Vincetoxicum species (Apocynaceae–Asclepiadoideae)

BackgroundDuring glacial periods, glacial advances caused temperate plant extirpation or retreat into localized warmer areas, and subsequent postglacial glacial retreats resulted in range expansions, which facilitated secondary contact of previously allopatric isolated lineages. The evolutionary outcomes of secondary contact, including hybrid zones, dynamic hybrid swarm, and resultant hybrid speciation, depends on the strengths of reproductive barriers that have arisen through epistatic and pleiotropic effects during allopatric isolation. The aim of this study was to demonstrate refugia isolation and subsequent secondary contact between two perennial Asclepioid species and to assess the genetic consequences of the secondary contact. We modeled the range shift of two ecologically distinct Vincetoxicum species using the species distribution model (SDM) and assessed the genetic consequences of secondary contact by combining morphological and genetic approaches. We performed morphometric analysis (592 individuals) and examined 10 nuclear microsatellites (671 individuals) in V. atratum, V. japonicum, and putative hybrid populations.ResultsMultivariate analysis, model-based Bayesian analysis, and non-model-based discriminant analysis of principal components confirmed the hybridization between V. atratum and V. japonicum. High pollen fertility and a lack of linkage disequilibrium suggested that the hybrid populations may be self-sustaining and have persisted since V. atratum and V. japonicum came into contact during the post-glacial period. Moreover, our findings show that the pattern of hybridization between V. atratum and V. japonicum is unidirectional and differs among populations. Geographically-isolated hybrid populations exist as genetically distinct hybrid swarms that consist of V. atratum-like genotypes, V. japonicum-like genotypes, or admixed genotypes. In addition, Bayesian-based clustering analysis and coalescent-based estimates of long-term gene flow showed patterns of introgressive hybridization in three morphologically ‘pure’ V. japonicum populations.ConclusionIn this study, we demonstrated that climatic oscillations during the Quaternary period likely led to species range shift and subsequently secondary contact. Hybrid populations may be self-sustaining and have persisted since V. atratum and V. japonicum came into contact during the post-glacial period. Pattern of hybridization between V. atratum and V. japonicum is unidirectional and differs among populations. We concluded that these differences in the genetic consequences of secondary contact are caused by historical colonization processes and/or natural selection.Electronic supplementary materialThe online version of this article (doi:10.1186/s12862-016-0587-2) contains supplementary material, which is available to authorized users.

A number of factors explain why WHO guideline developers make strong recommendations inconsistent with GRADE guidance

ObjectiveMany strong recommendations issued by the World Health Organization (WHO) are based on low- or very low-quality (low certainty) evidence (discordant recommendations). Many such discordant recommendations are inconsistent with the Grading of Recommendations Assessment, Development and Evaluation (GRADE) guidance. We sought to understand why WHO makes discordant recommendations inconsistent with GRADE guidance. Study Design and SettingWe interviewed panel members involved in guidelines approved by WHO (2007–2012) that included discordant recommendations. Interviews, recorded and transcribed, focused on use of GRADE including the reasoning underlying, and factors contributing to, discordant recommendations. ResultsFour themes emerged: strengths of GRADE, challenges and barriers to GRADE, strategies to improve GRADE application, and explanations for discordant recommendations. Reasons for discordant recommendations included skepticism about the value of making conditional recommendations; political considerations; high certainty in benefits (sometimes warranted, sometimes not) despite assessing evidence as low certainty; and concerns that conditional recommendations will be ignored. ConclusionWHO panelists make discordant recommendations inconsistent with GRADE guidance for reasons that include limitations in their understanding of GRADE. Ensuring optimal application of GRADE at WHO and elsewhere likely requires selecting panelists who have a commitment to GRADE principles, additional training of panelists, and formal processes to maximize adherence to GRADE principles.

Quantum charge pumping through fractional fermions in charge density modulated quantum wires and Rashba nanowires

We study the phenomenon of adiabatic quantum charge pumping in systems supporting fractionally charged fermionic bound states in two different setups. The first quantum pump setup consists of a charge density modulated quantum wire, and the second one is based on a semiconducting nanowire with Rashba spin-orbit interaction, in the presence of a spatially oscillating magnetic field. In both these quantum pumps transport is investigated in an N-X-N geometry, with the system of interest (X) connected to two normal-metal leads (N), and the two pumping parameters are the strengths of the effective wire-lead barriers. Pumped charge is calculated within the scattering matrix formalism. We show that quantum pumping in both setups provides a unique signature of the presence of the fractional-fermion bound states, in terms of the asymptotically quantized pumped charge. Furthermore, we investigate shot noise arising due to quantum pumping, verifying that the quantized pumped charge corresponds to minimal shot noise.

Quantifying Reproductive Barriers in a Sympatric Pair of Darter Species

Quantifying and comparing the strengths of different reproductive barriers between diverging lineages is especially useful for determining the evolutionary mechanisms driving speciation. Etheostoma barrenense and Etheostoma zonale are closely related sympatric species of darters that are sexually dimorphic and exhibit clear differences in male nuptial coloration. Prior studies demonstrated that these species exhibit complete behavioral isolation, and that both intraspecific and interspecific variation in male coloration play a role in female choice, all consistent with speciation by sexual selection on male nuptial color. Remaining unclear, however, is whether behavioral isolation is the strongest reproductive barrier between these species or, alternatively, whether additional reproductive barriers are equally strong, which could implicate mechanisms other than sexual selection in speciation. Here, we compare the relative strengths of multiple reproductive barriers between the two focal species, measuring: (1) ecological isolation, (2) gametic incompatibility, (3) hybrid inviability, (4) conspecific sperm precedence, and comparing these measures to a previously estimated strength of behavioral isolation. We find that behavioral isolation is the strongest reproductive barrier measured to date and suggest it may be the only barrier that has evolved to completion. This result provides additional empirical evidence for speciation driven by sexual selection and provides insight into the maintenance of sympatric species in nature.

Barriers to mammography and Pap smear screening among women who recently had neither, one or both types of screening.

There is legitimate concern about whether cancer screening programs and other types of prevention and early detection programs are designed to reach those most in need of services. Previous research on barriers to screening has generally addressed screening for specific cancers. The purpose of this study was to evaluate and compare the types and strengths of barriers to both mammography and Pap smear screening experienced by three groups of women. Five hundred and twenty-two women, aged 52-69, who were members of a large health maintenance organization (HMO), completed a survey about cancer screening and associated barriers. Women with no mammogram in the preceding 2 years and with no Pap smear in 3 years were classified into a "safety net" program. We classified women as falling into both (Pap smear and mammography), one (Pap smear or mammography), or neither safety nets. Results consistently revealed that women needing both tests had more numerous and more intense barriers than other women to both types of screening. Factor analyses and descriptive analyses both showed that the types of barriers experienced were very similar for mammography and Pap smear screening. The discussion addresses intervention implications and the additional research needed on women who need both mammogram and Pap smear screening and who have much higher cancer risk than other women.

Towards Digital Television in Europe

On the face of it, DTV would seem to be a technology for which consumer demand is weak at best. As a production, delivery and display innovation, its deployment is more obviously driven by a technological rather than an audience imperative. The major question hanging over its future is how this greatly enhanced distribution system will be supplied with programmes. Much of the debate on DTV so far has concentrated on engineering standards, delivery platforms and the impact of competition. Major film5V companies increasingly see the roll-out of DTV in the context of a “windowing” strategy, which serves to maximise profits by extending market reach over time as well as across territories. This will go some way towards answering the question of where significantly large new volumes of programming will be sourced in order to drive a “content is king” scenario. But there is the danger, for early adopters especially, that disillusionment may set in as the rhetoric of abundance, pushed hard by the TV industry for so long, is confronted by viewer realisation that “multiplexing” is really synonymous with “repeats,” thus elevating the existing problem of viewer resistance to repeats in analogue broadcasting to new heights. In Europe, there is little doubt that public service broadcasters should play a major role in content supply, beacuase of their vast archives of programming and their accumulated investment in production infrasctucture. But the strengths of both cultural affinities and barriers in existing, analogue TV markets must be carefully assessed before we can extrapolate to any new digital environment and the role of PSB in it. We must also assess the current tensions between public and private TV systems, intensely focussed on the European Commission and its relationship with national governments since the adoption of the Protocol of the Amsterdam Treaty, in particular the guerrilla war being waged against the EBU, the attempt to redefine PSB as a set of programming genres, the contention that the licence fee is a form of “state aid” and the argument that PSB will be competing unfairly with private TV interersts if allowed to develop “new services.”

Electron transport in the presence of random impurities: Transition from ballistic to diffusive regimes.

A transport theory is developed for multibarrier mesoscopic devices that contain a random configuration of short-range impurity potentials. The theory is based on the self-consistent second Born approximation within the Keldysh formulation. The self-energy of the system is estimated to describe the average two-terminal resistance of an ensemble of nearly identical systems. The theory describes the transition from the ballistic to the diffusive regime of operation as a function of a disorder parameter characterizing the density as well as the strength of the impurities. It is shown that as the strengths of the elastic tunnel barriers are increased, the transition from ballistic to diffusion regime occurs at larger values of the disorder parameter.