Clustering Phase Transitions and Hysteresis: Pitfalls in Constructing Network Ensembles

Ensembles of networks are used as null models in many applications. However, simple null models often show much less clustering than their real-world counterparts. In this paper, we study a model where clustering is enhanced by means of a fugacity term as in the Strauss (or "triangle") model, but where the degree sequence is strictly preserved -- thus maintaining the quenched heterogeneity of nodes found in the original degree sequence. Similar models had been proposed previously in [R. Milo et al., Science 298, 824 (2002)]. We find that our model exhibits phase transitions as the fugacity is changed. For regular graphs (identical degrees for all nodes) with degree k > 2 we find a single first order transition. For all non-regular networks that we studied (including Erdos - Renyi and scale-free networks) we find multiple jumps resembling first order transitions, together with strong hysteresis. The latter transitions are driven by the sudden emergence of "cluster cores": groups of highly interconnected nodes with higher than average degrees. To study these cluster cores visually, we introduce q-clique adjacency plots. We find that these cluster cores constitute distinct communities which emerge spontaneously from the triangle generating process. Finally, we point out that cluster cores produce pitfalls when using the present (and similar) models as null models for strongly clustered networks, due to the very strong hysteresis which effectively leads to broken ergodicity on realistic time scales.Comment: 13 pages, 11 figure

Link and subgraph likelihoods in random undirected networks with fixed and partially fixed degree sequence

The simplest null models for networks, used to distinguish significant features of a particular network from {\it a priori} expected features, are random ensembles with the degree sequence fixed by the specific network of interest. These "fixed degree sequence" (FDS) ensembles are, however, famously resistant to analytic attack. In this paper we introduce ensembles with partially-fixed degree sequences (PFDS) and compare analytic results obtained for them with Monte Carlo results for the FDS ensemble. These results include link likelihoods, subgraph likelihoods, and degree correlations. We find that local structural features in the FDS ensemble can be reasonably well estimated by simultaneously fixing only the degrees of few nodes, in addition to the total number of nodes and links. As test cases we use a food web, two protein interaction networks (\textit{E. coli, S. cerevisiae}), the internet on the autonomous system (AS) level, and the World Wide Web. Fixing just the degrees of two nodes gives the mean neighbor degree as a function of node degree, $_k$, in agreement with results explicitly obtained from rewiring. For power law degree distributions, we derive the disassortativity analytically. In the PFDS ensemble the partition function can be expanded diagrammatically. We obtain an explicit expression for the link likelihood to lowest order, which reduces in the limit of large, sparse undirected networks with $L$ links and with $k_{\rm max} \ll L$ to the simple formula $P(k,k') = kk'/(2L + kk')$. In a similar limit, the probability for three nodes to be linked into a triangle reduces to the factorized expression $P_{\Delta}(k_1,k_2,k_3) = P(k_1,k_2)P(k_1,k_3)P(k_2,k_3)$.Comment: 17 pages, includes 11 figures; first revision: shortened to 14 pages (7 figures), added discussion of subgraph counts, deleted discussion of directed network

Using an Implementation Research Framework to Identify Potential Facilitators and Barriers of an Intervention to Increase HPV Vaccine Uptake

Background: Although the incidence of cervical cancer has been decreasing in the United States over the last decade, Hispanic and African American women have substantially higher rates than Caucasian women. The human papillomavirus (HPV) is a necessary, although insufficient, cause of cervical cancer. In the United States in 2013, only 37.6% of girls 13 to 17 years of age received the recommended 3 doses of a vaccine that is almost 100% efficacious for preventing infection with viruses that are responsible for 70% of cervical cancers. Implementation research has been underutilized in interventions for increasing vaccine uptake. The Consolidated Framework for Implementation Research (CFIR), an approach for designing effective implementation strategies, integrates 5 domains that may include barriers and facilitators of HPV vaccination. These include the innovative practice (Intervention), communities where youth and parents live (Outer Setting), agencies offering vaccination (Inner Setting), health care staff (Providers), and planned execution and evaluation of intervention delivery (Implementation Process). Methods: Secondary qualitative analysis of transcripts of interviews with 30 community health care providers was conducted using the CFIR to code potential barriers and facilitators of HPV vaccination implementation. Results: All CFIR domains except Implementation Process were well represented in providers\u27 statements about challenges and supports for HPV vaccination. Conclusion: A comprehensive implementation framework for promoting HPV vaccination may increase vaccination rates in ethnically diverse communities. This study suggests that the CFIR can be used to guide clinicians in planning implementation of new approaches to increasing HPV vaccine uptake in their settings. Further research is needed to determine whether identifying implementation barriers and facilitators in all 5 CFIR domains as part of developing an intervention contributes to improved HPV vaccination rates

Are Training and Experience adapting Evidence-Based interventions associated With Self-Efficacy and attitudes? a Cross-Sectional Survey of Students and Practitioners With Varying Levels of adaptation Experience

Increasing use of evidence-based interventions (EBIs) in local settings will help reduce the research-practice gap and improve health equity. Because adaptation to new settings and populations is essential to effective EBI use, frameworks to guide practice are receiving more attention; most, however, only provide broad guidelines without instructions for making adaptations in practice. Therefore, practitioners may need additional training or technical assistance (TA) to implement and adapt EBIs. This study explores whether practitioners\u27 and students\u27 general EBI training or TA and level of adaptation experience are associated with self-efficacy in adapting EBIs and with attitudes toward EBI use. We analyzed baseline survey data of participants in an evaluation of IM-Adapt Online, a newly developed decision support tool. We asked about previous training on EBIs, general and specific adaptation behaviors, and attitudes toward EBIs and found an association between previous training or TA in using EBIs with higher self-efficacy for using and adapting EBIs. Respondents with prior EBI training were significantly more likely to have higher self-efficacy in EBI behaviors across subdomains and in total than those without training. Respondents reported lowest self-efficacy for planning adaptations

Evidence-Based intervention (Ebi) Mapping: a Systematic approach to Understanding the Components and Logic of Ebis

BACKGROUND: Despite the development of numerous evidence-based interventions (EBIs), many go unused in practice. Hesitations to use existing EBIs may be due to a lack of understanding about EBI components and what it would take to adapt it or implement it as designed. to improve the use of EBIs, program planners need to understand their goals, core components, and mechanisms of action. This paper presents EBI Mapping, a systematic approach based on Intervention Mapping, that can be used to understand and clearly describe EBIs, and help planners put them into practice. METHODS: We describe EBI Mapping tasks and provide an example of the process. EBI Mapping uses principles from Intervention Mapping, a systematic framework for planning multilevel health promotion interventions. EBI Mapping applies the Intervention Mapping steps retrospectively to help planners understand an existing EBI (rather than plan a new one). We explain each EBI Mapping task and demonstrate the process using the VERB Summer Scorecard (VSS), a multi-level community-based intervention to improve youth physical activity. RESULTS: EBI Mapping tasks are: 1) document EBI materials and activities, and their audiences, 2) identify the EBI goals, content, and mechanisms of action, 3) identify the theoretical change methods and practical applications of those methods, 4) describe design features and delivery channels, and 5) describe the implementers and their tasks, implementation strategies, and needed resources. By applying the EBI Mapping tasks, we created a logic model for the VSS intervention. The VSS logic model specifies the links between behavior change methods, practical applications, and determinants for both the at-risk population and environmental change agents. The logic model also links the respective determinants to the desired outcomes including the health behavior and environmental conditions to improve the health outcome in the at-risk population. CONCLUSIONS: EBI Mapping helps program planners understand the components and logic of an EBI. This information is important for selecting, adapting, and scaling-up EBIs. Accelerating and improving the use of existing EBIs can reduce the research-to-practice gap and improve population health

Psychosocial concerns and needs of cancer survivors treated at a comprehensive cancer center and a community safety net hospital

The number of cancer survivors in the United States is expected to grow to 18 million by 2020 because of improved cancer treatment outcomes and the aging of the population.[1] Many cancer survivors are at increased risk for cancer recurrence and other adverse long-term physical and psychosocial conditions.[2-5] Disparities in survival are associated with inadequate or no health insurance coverage because individuals are more likely to be diagnosed with cancer at later stages,[6] and higher incidence for some cancers among African Americans.[7] Few studies have examined psychosocial health disparities during cancer survivorship,[8-13] and little is known about how psychosocial factors subsequent to diagnosis affect survival and long-term outcomes. [4,14] While clinical care relevant to survivorship outcomes is advancing, [15, 16] optimal practices for preparing survivors for treatment and transitioning off treatment have yet to be defined. [11, 15, 17] Furthermore, guidance is needed for serving minority and underserved survivor populations where health disparities exist.[7] More data are needed about incidence of adverse outcomes and their determinants, overall and in disparity populations to inform development of best practices for preventive interventions. The purpose of this study was to identify similarities and differences among two groups of survivors in (1) sources of information at time of cancer diagnosis, (2) sources of support used during and after treatment, (3) stressors and challenges during and after treatment, and (4) coping strategies[18] used during and following cancer treatment. These factors might be associated with health services use,[19] and with survivorship disparities.[20] One group was treated at Vanderbilt-Ingram Cancer Center (VICC), an NCI-designated comprehensive cancer center, and the other at Meharry Medical College (MMC), its partner medical setting that serves patients who are mostly publicly-insured and uninsured. Secondary analysis of data from focus group participants was undertaken to address the four study topics and to guide future development of interventions tailored to preferences and needs of diverse survivors

Time from Screening Mammography to Biopsy and from Biopsy to Breast Cancer Treatment among Black and White, Women Medicare Beneficiaries Not Participating in a Health Maintenance Organization

Purpose There is a breast cancer mortality gap adversely affecting Black women in the United States. This study assessed the relationship between number of days between abnormal mammogram, biopsy, and treatment among Medicare (Part B) beneficiaries ages 65 to 74 and 75 to 84 years, accounting for race and comorbidity. Methods A cohort of non-Hispanic Black and non-Hispanic White women residing in the continental United States and receiving no services from a health maintenance organization was randomly selected from the Center for Medicare and Medicaid Services denominator file. The cohort was followed from 2005 to 2008 using Center for Medicare and Medicaid Services claims data. The sample included 4,476 women (weighted n = 70,731) with a diagnosis of breast cancer. Cox proportional hazard modeling was used to identify predictors of waiting times. Findings Black women had a mean of 16.7 more days between biopsy and treatment (p \u3c .001) and 15.7 more days from mammogram to treatment (p = .003) than White women. Median duration from abnormal mammogram to treatment exceeded National Quality Measures for Breast Centers medians regardless of race, age, or number of comorbidities (overall 43 days vs. the National Quality Measures for Breast Centers value of 28 days). Conclusions Medical care delays may contribute, in part, to the widening breast cancer mortality gap between Black women and White women. Further study, with additional clinical and social information, is needed to broaden scientific understanding of racial determinants and assess the clinical significance of mammogram to treatment times among Medicare beneficiaries

Punching shear strength of steel fibre reinforced concrete slabs

The ultimate strength of reinforced concrete slabs is frequently governed by the punching shear capacity, which may be increased with addition of traditional fitments such as reinforcing steel, headed studs or shear heads. In addition to these traditional methods of strengthening against punching, steel fibre reinforcement has proved to be an effective and viable alternative. The addition of fibres into the concrete improves not only the shear behaviour but also the deformation capacity of reinforced concrete slabs. This paper presents a mechanical model for predicting the punching strength and behaviour of concrete slabs reinforced with steel fibres as well as conventional reinforcement. The proposed model is validated against a wide number of available experimental data and its accuracy is verified. On this basis, a simple design equation for the punching shear capacity of steel fibre reinforced concrete (SFRC) slabs is proposed

Interstitial lung abnormality is prevalent and associated with worse outcome in patients undergoing transcatheter aortic valve replacement

BackgroundInterstitial lung abnormality (ILA) is found in 5-10% of the general population and is associated with increased mortality risk. Risk factors for ILA, including advanced age and smoking history also increase the risk for aortic stenosis (AS). Transcatheter aortic valve replacement (TAVR) has become an increasingly utilized intervention for patients with severe AS, and requires a high-resolution computed tomography (HRCT) of the chest to assess aortic valve dimensions.ObjectivesTo determine the prevalence and clinical significance of ILA on HRCT performed in patients referred for TAVR.MethodsConsecutive pre-TAVR HRCTs performed over a 5-year period were reviewed. ILA was defined as bilateral, nondependent reticular opacities. All-cause mortality among TAVR recipients was compared between ILA cases and non-ILA controls matched 2:1 by age and gender using Cox proportional hazards regression and the Kaplan Meier estimator.ResultsOf 623 HRCTs screened, ILA was detected in 92 (14.7%), including 62 patients that underwent TAVR. Among ILA cases, 17 (27.4%) had a typical or probable usual interstitial pneumonia pattern, suggesting a diagnosis of idiopathic pulmonary fibrosis. Survival was worse in ILA cases compared to non-ILA controls (p = 0.008) and ILA was an independent predictor of mortality after multivariable adjustment (HR 3.29, 95% CI 1.34-8.08; p = 0.009).ConclusionsILA is a common finding among patients with severe AS and is associated with increased mortality in those undergoing TAVR. Further research is needed to elucidate the biology underpinning this observation and determine whether ILA evaluation and risk stratification modulates this mortality risk

Economic development, human development, and the pursuit of happiness, April 1, 2, and 3, 2004

This repository item contains a single issue of the Pardee Conference Series, a publication series that began publishing in 2006 by the Boston University Frederick S. Pardee Center for the Study of the Longer-Range Future. This was the Center's spring conference, which took place during April 1, 2, and 3, 2004.The conference asks the questions, how can we make sure that the benefits of economic growth flow into health, education, welfare, and other aspects of human development; and what is the relationship between human development and economic development? Speakers and participants discuss the role that culture, legal and political institutions, the UN Developmental Goals, the level of decision-making, and ethics, play in development