43 research outputs found
Non-Invasive Measure of Stenosis Severity Through Spectral Analysis [post-print]
A preliminary study on the effect of stenosis severity in a restricted flow is performed through the spectral analysis of sound signals. A model pulsatile flow that uses differing area reductions through an opening was employed, where contact microphones secured outside of the reduction measured the sound intensity in the flow. A spectral analysis shows the narrowing results in increased magnitude of frequencies in the range of 15 to 170Hz, with different narrowing cases resulting in different peak frequencies. Low frequency content up to 10 Hz remains approximately unchanged. This simplistic approach of signal processing forms a basis for enhanced understanding and diagnosis of the severity of narrowing in an internal flow, and encourages future research into more complicated bispectral methods of analysis. The results show a clear difference between regular turbulence present in an internal flow and enhanced turbulence due to a stenosis or similar restriction in the flow
Examining the inertial subrange with nanoscale cross-wire measurements of turbulent pipe flow at high Reynolds number near the centreline [post-print]
Highly resolved, two-component velocity measurements were made near the centreline of turbulent pipe flow for Reynolds numbers in the range . These unique data were obtained with a nanoscale cross-wire probe and used to examine the inertial subrange scaling of the longitudinal and transverse velocity components. Classical dissipation rate estimates were made using both the integration of one-dimensional dissipation spectra for each velocity component and the third-order moment of the longitudinal structure function. Although the second-order moments and one-dimensional spectra for each component showed behaviour consistent with local isotropy, clear inertial range similarity and behaviour were not exhibited in the third-order structure functions at these Reynolds numbers. When corrected for the effects of radial inhomogeneities at the centreline following the generalized expression of Danaila et al. (J. Fluid Mech., vol. 430, 2001, pp. 87-109), re-derived for the pipe flow domain, the third-order moments of the longitudinal structure function exhibited a clearer plateau per the classical Kolmogorov \u27four-fifths law\u27. Similar corrections described by Danaila et al. (J. Fluid Mech., vol. 430, 2001, pp. 87-109) applied to the analogous equation for the mixed structure functions (i.e. the \u27four-thirds law\u27) also yielded improvement over all ranges of scale, improving with increasing Reynolds number. The rate at which the \u27four-fifths\u27 law and \u27four-thirds\u27 law were approached by the third-order structure functions was found to be more gradual than decaying isotropic turbulence for the same Reynolds numbers
Logarithmic scaling of higher-order temperature moments in the atmospheric surface layer
A generalized logarithmic law for high-order moments of passive scalars is
proposed for turbulent boundary layers. This law is analogous to the
generalized log law that has been proposed for high-order moments of the
turbulent longitudinal velocity and is derived by combining the random sweeping
decorrelation hypothesis with a spectral model informed by the attached eddy
hypothesis. The proposed theory predicts that the high-order moments of passive
scalar fluctuations within the inertial sublayer will vary logarithmically with
wall-normal distance (). The proposed theory is evaluated using high
frequency time-series measurements of temperature and streamwise velocity
fluctuations obtained in the first meter of the atmospheric surface layer (ASL)
under near-neutral thermal stratification. The logarithmic dependence with
within the inertial sublayer is observed in both the air temperature and
velocity moments, with good agreement to the predictions from the proposed
theory. Surprisingly, the proposed theory appears to be as, if not more, valid
for transported passive scalars than for the longitudinal velocity
Routes for breaching and protecting genetic privacy
We are entering the era of ubiquitous genetic information for research,
clinical care, and personal curiosity. Sharing these datasets is vital for
rapid progress in understanding the genetic basis of human diseases. However,
one growing concern is the ability to protect the genetic privacy of the data
originators. Here, we technically map threats to genetic privacy and discuss
potential mitigation strategies for privacy-preserving dissemination of genetic
data.Comment: Draft for comment
Clinical Sequencing Exploratory Research Consortium: Accelerating Evidence-Based Practice of Genomic Medicine
Despite rapid technical progress and demonstrable effectiveness for some types of diagnosis and therapy, much remains to be learned about clinical genome and exome sequencing (CGES) and its role within the practice of medicine. The Clinical Sequencing Exploratory Research (CSER) consortium includes 18 extramural research projects, one National Human Genome Research Institute (NHGRI) intramural project, and a coordinating center funded by the NHGRI and National Cancer Institute. The consortium is exploring analytic and clinical validity and utility, as well as the ethical, legal, and social implications of sequencing via multidisciplinary approaches; it has thus far recruited 5,577 participants across a spectrum of symptomatic and healthy children and adults by utilizing both germline and cancer sequencing. The CSER consortium is analyzing data and creating publically available procedures and tools related to participant preferences and consent, variant classification, disclosure and management of primary and secondary findings, health outcomes, and integration with electronic health records. Future research directions will refine measures of clinical utility of CGES in both germline and somatic testing, evaluate the use of CGES for screening in healthy individuals, explore the penetrance of pathogenic variants through extensive phenotyping, reduce discordances in public databases of genes and variants, examine social and ethnic disparities in the provision of genomics services, explore regulatory issues, and estimate the value and downstream costs of sequencing. The CSER consortium has established a shared community of research sites by using diverse approaches to pursue the evidence-based development of best practices in genomic medicine
Theoretical and experimental investigations of similarity solutions in turbulent flows
An investigation of turbulent flows is performed through seeking similarity solutions to their governing equations. A combination of theoretical, experimental, and numerical approaches are utilized to validate the resulting scaling parameters and solutions.
A two-point, two-time similarity solution is found for the velocity correlation in a decaying homogeneous turbulence field. The solution reduces to previous single-point, single-time solutions when the appropriate limit is taken. Relations to classic isotropic results are investigated, with additional symmetries to the equation of motion proposed. The implications on the simplifications of the Lumley POD integral are discussed.
A new theory for the temperature distribution in a developing turbulent thermal boundary layer is obtained, resulting in two different possible sets of scaling parameters for the inner and outer flows. The overlap-layer profile and resulting heat transfer law are both described by a power law. Extending the scaling and similarity analysis to the temperature variance field results in power laws for both the overlap-layer profile and so-called “variance law,” which is found to be directly tied to the heat transfer law. An additional Reynolds number dependent parameter, unique to the variance field, is discussed.
New velocity and temperature sensors are developed for flow measurements to assist in these investigations. Initial utilization of nanoscale wires to measure temperature in a water channel resulted in conflated velocity and temperature measurements, prompting this new sensor development. Theoretical models inform the design, while experimental results show their performance in the turbulent boundary layer as well as laminar flow applications. The velocity sensors are demonstrated as mechanically and electrically minimalistic compared to classic devices, with future design considerations made for thermal applications
Development and psychometric properties of the Female Sexual Desire Questionnaire (FSDQ)
Introduction.  Sexual desire is often evaluated as part of a global assessment of female sexual function, which may not comprehensively evaluate the various facets of this experience. There currently exists a need to develop a psychometrically robust desire-specific measure for women.Aim.  The aim of this study was to develop and validate a desire-specific, self-administered instrument that evaluates the multiple facets of sexual desire and factors influencing this experience for partnered heterosexual women, with or without sexual dysfunction.Methods.  Preliminary items for inclusion in the Female Sexual Desire Questionnaire (FSDQ) were identified through a literature review and individual interviews with partnered heterosexual women, mostly from Australia. The resulting instrument was completed by a validation sample of 741 women, aged between 18 and 71 years, who were involved in a heterosexual relationship of between 3 months\u27 and 49 years\u27 duration.Main Outcome Measures.  Exploratory factor analysis was used to refine the FSDQ item content and identify the underlying domain structure. The reliability (internal consistency) and validity (convergent validity) of the FSDQ were also evaluated.Results.  The final version of the FSDQ consisted of 50 items organized into six domains that characterized the experience of, and factors influencing, sexual desire for heterosexual partnered women: Dyadic Desire, Solitary Desire, Resistance, Positive Relationship, Sexual Self-Image, and Concern. Each domain demonstrated high reliability, as did the overall measure. Evidence of construct validity was ascertained through convergence with the Sexual Desire Inventory and the Hurlbert Index of Sexual Desire. A short-form of the FSDQ, consisting of six items, was also developed.Conclusions.  The FSDQ is a new reliable and valid multidimensional measure designed specifically for evaluating the facets of, and factors influencing, sexual desire among sexually functional and dysfunctional women who are involved in a heterosexual relationship.<br /