551 research outputs found
Heart rate variability in a patient after percutaneous renal denervation: a case report
The overactivity of sympathetic component of autonomic nervous system is implicated in the genesis and progression of hypertension. We report the heart rate variability (HRV) of a patient after renal denervation for treatment of medically resistant hypertension. Catheter based renal denervation done for treatment of resistant hypertension reduces blood pressure by reducing the central sympathetic drive. In the present study we found a significant decrease in low frequency component of HRV in one month follow-up period after the procedure. We propose a simple, non-invasive 5-minute HRV could be a predictor of effective renal sympathetic denervation
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Improved methods for the analysis of circadian rhythms in correlated gene expression data
Circadian clocks regulate biological behaviours, such as sleeping and waking times, that recur naturally on an approximately 24-hour cycle. These clocks tend to be influenced by a variety of external factors, sometimes to the extent that it can have an impact on health. As an example in pharmacology, the effects of chemicals on the circadian rhythm in patients can be key in clarifying the relationship of drug efficacy and toxicity with dosing times. While pre-clinical experiments conducted to elucidate these effects may produce correlated data measured over time, such as gene expression profiles, existing methods for fitting parametric nonlinear regression models are however inadequate and can lead to unreliable, inconsistent parameter estimates and invalid inference. A de-trending method is widely used as a pre-processing step to address the non-stationary problem in the data before fitting models based on the assumption of independence. However, as it is unclear that this approach properly accounts for the correlation structure, alternative methods that specifically model the correlation in the data based on conditional least squares and a two-stage estimation procedure are proposed and evaluated. A simulation study covering a wide range of scenarios and models show that the proposed methods more efficient and robust to model mis-specification than de-trending and, furthermore, they lead to reduced bias in estimation of the circadian period and more reliable confidence intervals
Nonlinear ptychographic coherent diffractive imaging
Ptychographic Coherent diffractive imaging (PCDI) is a significant advance in imaging allowing the measurement of the full electric field at a sample without use of any imaging optics. So far it has been confined solely to imaging of linear optical responses. In this paper we show that because of the coherence-preserving nature of nonlinear optical interactions, PCDI can be generalised to nonlinear optical imaging. We demonstrate second harmonic generation PCDI, directly revealing phase information about the nonlinear coefficients, and showing the general applicability of PCDI to nonlinear interactions
Who said that? Impact of source expertise: A generations focused experiment on the perception of radio news sources’ gender, ethos and expertise
Building on previous research exploring effects of spokesperson type and gender on audience perceptions of spokesperson and message credibility, this study focused on effects of news sources specifically for radio news. This was one of the first studies to explore the effects
of source type (journalist or outside expert) and gender on perceptions of source and message credibility, and message importance for the general U.S. population. A 2 x 2 experiment was performed with 900 participants, and analysis found that source type and gender had significant
impact on audience perceptions of source and the message. We further analyzed these effects breaking down the audience based on generations and gender and found similar results. The results of the analyses reveal some interesting findings, especially in the areas of choice of
media for news, sexism in the news, etc., that need to be further explored
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The efficiency of single SNP and SNP-set analysis in genome-wide association studies
The objective of this research is to compare and identify effective methods for the identification of gene loci associated with a disease outcome in the analysis of
genome-wide data. We evaluate three methods which are single SNP analysis, Sequence Kernel Association Test (SKAT) and the recently proposed Generalized Higher
Criticism (GHC). The simulated data used in this research were constructed from a control data set in a study of Crohn's disease. True positive (TP) and false positive rate (FP) were evaluated under different genetic models for disease with significant thresholds adjusted for multiple hypothesis testing based on the permutation method. The findings are mixed with all three methods giving similar TP rates under some disease models and different rates for other models. Overall, GHC is shown to be preferable in terms of error rates but it is disadvantageous in terms of computational efficiency
Spiral of Silence in an Algorithm-Driven Social Media Content Environment: Conceptual Framework and Research Propositions
The aim of this conceptual study is to explore the major tenets of the spiral of silence theory (i.e., fear of isolation, willingness to speak out, quasi-statistical sense) within social media environments, where users are predominantly shown content that aligns with their views
and interests. In this environment of algorithmic-suggested content, the researchers offer several propositions as to how the spiral of silence tenets operate relative to the perceived anonymity, tie strengths, and the postings suggested by programmed algorithms used by social
media platforms. New research directions on spiral of silence theory, social media communication, and opinion polarization are also discussed. Finally, implications for
researchers, policymakers, and social media practitioners are addressed
Student’s Perceptions of Spiritual Preparedness and Contribution to their Community Following An Emergency Preparedness Interprofessional Collaborative Practice Simulation
This presentation highlights findings from a study exploring student perceptions of spirituality and contributing to their community after participating in an emergency preparedness interprofessional simulation. Mixed methods were utilized and an online survey was emailed to a convenience sample (N=338). The majority self-reported they can better contribute to their community
Exploring semantic verbal fluency patterns and their relationship to age and Alzheimer's disease in adults with Down syndrome
Introduction: Adults with Down syndrome (DS) are at ultra-high risk of developing Alzheimer's disease (AD), characterized by poor episodic memory and semantic fluency in the preclinical phase in the general population. We explored semantic fluency performance in DS and its relationship to age, AD, and blood biomarkers. Methods: A total of 302 adults with DS at baseline and 87 at follow-up from the London Down Syndrome Consortium cohort completed neuropsychological assessments. Blood biomarkers were measured with the single molecule array technique in a subset of 94 participants. Results: Poorer verbal fluency performance was observed as age increases. Number of correct words declined in those with AD compared to those without over 2 years and was negatively correlated with neurofilament light (r = –0.37, P =.001) and glial fibrillary acidic protein (r = –0.31, P =.012). Discussion: Semantic fluency may be useful as an early indicator of cognitive decline and provide additional information on AD-related change, showing associations with biomarkers in DS
Human palatine tonsil: a new potential tissue source of multipotent mesenchymal progenitor cells
INTRODUCTION: Mesenchymal progenitor cells (MPCs) are multipotent progenitor cells in adult tissues, for example, bone marrow (BM). Current challenges of clinical application of BM-derived MPCs include donor site morbidity and pain as well as low cell yields associated with an age-related decrease in cell number and differentiation potential, underscoring the need to identify alternative sources of MPCs. Recently, MPC sources have diversified; examples include adipose, placenta, umbilicus, trabecular bone, cartilage, and synovial tissue. In the present work, we report the presence of MPCs in human tonsillar tissue. ----- METHODS: We performed comparative and quantitative analyses of BM-MPCs with a subpopulation of adherent cells isolated from this lymphoid tissue, termed tonsil-derived MPCs (T-MPCs). The expression of surface markers was assessed by fluorescent-activated cell sorting analysis. Differentiation potential of T-MPCs was analyzed histochemically and by reverse transcription-polymerase chain reaction for the expression of lineage-related marker genes. The immunosuppressive properties of MPCs were determined in vitro in mixed lymphocyte reactions. ----- RESULTS: Surface epitope analysis revealed that T-MPCs were negative for CD14, CD31, CD34, and CD45 expression and positive for CD29, CD44, CD90, and CD105 expression, a characteristic phenotype of BM-MPCs. Similar to BM-MPCs, T-MPCs could be induced to undergo adipogenic differentiation and, to a lesser extent, osteogenic and chondrogenic differentiation. T-MPCs did not express class II major histocompatibility (MHC) antigens, and in a similar but less pronounced manner compared with BM-MPCs, T-MPCs were immunosuppressive, inhibiting the proliferation of T cells stimulated by allogeneic T cells or by non-specific mitogenic stimuli via an indoleamine 2,3-dioxygenase-dependent mechanism. ----- CONCLUSION: Human palatine T-MPCs represent a new source of progenitor cells, potentially applicable for cell-based therapies
Black pitch, carved histories: radiocarbon dating, wood species identification and strontium isotope analysis of prehistoric wood carvings from Trinidad's Pitch Lake
We report on the results of a multi-disciplinary project (including wood identification, radiocarbon dating and strontium isotope analysis) focused on a collection of pre-Columbian wooden carvings and human remains from Pitch Lake, Trinidad. While the lake's unusual conditions are conducive to the survival of organic artefacts, they also present particular challenges for analysis. There is a loss of any contextual association beyond that of the lake, and specific methodologies are required to deal with pitch contamination. A surprising taxonomic range of woods was employed for the various utilitarian and ceremonial items recovered. The 14C results range from ca. 3200 BCE to ca. 700 CE, and include the earliest known wooden carvings in the entire Caribbean. The strontium isotope results - interpreted with the aid of an isoscape developed for the project, based on extensive samples of modern trees across Trinidad and Tobago - indicate that most carvings are consistent with the site's immediate environs; however, a ‘weaving tool’ came from a more radiogenic region that is unlikely to be found on Trinidad, suggesting links with the South American mainland
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