A Canonical Biomechanical Vocal Fold Model

The present article aimed at constructing a canonical geometry of the human vocal fold (VF) from subject-specific image slice data. A computer-aided design approach automated the model construction. A subject-specific geometry available in literature, three abstractions (which successively diminished in geometric detail) derived from it, and a widely used quasi two-dimensional VF model geometry were used to create computational models. The first three natural frequencies of the models were used to characterize their mechanical response. These frequencies were determined for a representative range of tissue biomechanical properties, accounting for underlying VF histology. Compared with the subject-specific geometry model (baseline), a higher degree of abstraction was found to always correspond to a larger deviation in model frequency (up to 50% in the relevant range of tissue biomechanical properties). The model we deemed canonical was optimally abstracted, in that it significantly simplified the VF geometry compared with the baseline geometry but can be recalibrated in a consistent manner to match the baseline response. Models providing only a marginally higher degree of abstraction were found to have significant deviation in predicted frequency response. The quasi two-dimensional model presented an extreme situation: it could not be recalibrated for its frequency response to match the subject-specific model. This deficiency was attributed to complex support conditions at anterior-posterior extremities of the VFs, accentuated by further issues introduced through the tissue biomechanical properties. In creating canonical models by leveraging advances in clinical imaging techniques, the automated design procedure makes VF modeling based on subject-specific geometry more realizable

3D flow in the venom channel of a spitting cobra: do the ridges in the fangs act as fluid guide vanes?

The spitting cobra Naja pallida can eject its venom towards an offender from a distance of up to two meters. The aim of this study was to understand the mechanisms responsible for the relatively large distance covered by the venom jet although the venom channel is only of micro-scale. Therefore, we analysed factors that influence secondary flow and pressure drop in the venom channel, which include the physical-chemical properties of venom liquid and the morphology of the venom channel. The cobra venom showed shear-reducing properties and the venom channel had paired ridges that span from the last third of the channel to its distal end, terminating laterally and in close proximity to the discharge orifice. To analyze the functional significance of these ridges we generated a numerical and an experimental model of the venom channel. Computational fluid dynamics (CFD) and Particle-Image Velocimetry (PIV) revealed that the paired interior ridges shape the flow structure upstream of the sharp 90° bend at the distal end. The occurrence of secondary flow structures resembling Dean-type vortical structures in the venom channel can be observed, which induce additional pressure loss. Comparing a venom channel featuring ridges with an identical channel featuring no ridges, one can observe a reduction of pressure loss of about 30%. Therefore it is concluded that the function of the ridges is similar to guide vanes used by engineers to reduce pressure loss in curved flow channels

Синтез и исследование наночастиц магнетита и композитов на его основе

В работе наночастицы Fe3O4 и композиты Fe3O4/rGO с высокой намагниченностью насыщения были синтезированы методом совместного осаждения в различных условиях с добавлением лимонной кислоты для применения в области биомедицины. Исследовано влияние условий синтеза и добавления лимонной кислоты на магнитные свойства полученных образцов.In this work, Fe3O4 nanoparticles and Fe3O4/rGO composites with high saturation magnetization were synthesized by co-precipitation under various conditions with the addition of citric acid for use in the field of biomedicine. The influence of the conditions of synthesis and addition of citric acid on the magnetic properties of the obtained samples was investigated

Acute Kidney Injury, the Present on Admission indicator (POA) and sex disparities: Observational study of inpatient real world data in a Swiss tertiary health care system

AbstractBackgroundRegarding kidney disease, sex differences in epidemiology and clinical relevance have been reported. Related to absolute and relative changes of baseline creatinine, different criteria for staging may induce under-or over-diagnosis related to sex. At the largest Swiss provider of inpatient acute health care, a clinic decision support algorithm ensures exact staging of kidney disease (2012 KDIGO Clinical Practice Guideline). Coding of the indicator “Present On Admission” was introduced at this institution in 2018 to flag post-admission conditions.ObjectiveWe hypothesized sex differences in health care associated acute kidney injury. Defined indicators and the distribution of stages in acute kidney injury were analysed using the POA flag. Sex differences were reported.MethodsRetrospective observational study. Routinely collected health data, Insel Group, Berne, Switzerland, 2019 and 2020 (121’757 cases) on the patient history and intensive care treatment duration, comorbidity levels, coded diagnoses, age and sex. Software and statistic: program R, version 4.1.1, standard deviation; median, interquartile range; prop.test; standardized mean difference.ResultsThe reporting of post-admission diagnoses was associated with more interhospital transfers, intensive care stays, scores of severity and treatment intensity, mechanical ventilation, age, number of diagnoses, complexity level of the related cases and mortality. A weaker association could be observed for the female population. However, mortality was higher (stage III acute kidney injury 41.6%).ConclusionUsing the POA-flag the results reflect the clinical situation of complications and comorbidities evolving unexpectedly. As our results show sex differences, i.e. a lower morbidity of female patients for each stage, but a higher mortality, a deeper evaluation of the implied sex differences in staging of kidney disease should follow.The general results confirm the necessity of a diagnosis-onset reporting in health statistic.</jats:sec

Acute kidney injury, the present on admission (POA) indicator and sex disparities: observational study of inpatient real-world data in a Swiss tertiary healthcare system. Explorative analysis

Background Regarding kidney disease (KD), sex differences in epidemiology and clinical relevance have been reported. Related to absolute and relative changes of baseline creatinine, different criteria for staging may induce underdiagnosis or overdiagnosis related to sex. At the largest Swiss provider of inpatient acute healthcare, a clinic decision support algorithm ensures exact staging of KD (2012 KDIGO Kidney Disease Improving Global Outcomes Clinical Practice Guideline). Coding of the indicator ‘Present On Admission’ (POA) was introduced at this institution in 2018 to flag postadmission conditions.Objective The explorative analysis aimed at differences in diagnosis groups. Defined indicators and the distribution of stages in acute kidney injury (AKI) were analysed using the POA flag. Sex differences were reported.Methods Retrospective observational study. Explorative analysis. Routinely collected health data, 2019 and 2020 (121 757 cases) on the patient history and intensive care treatment duration, comorbidity levels, coded diagnoses, age and sex.Software and statistic: program R, V.4.1.1, SD; median, IQR; prop.test; standardised mean difference.Results The reporting of postadmission diagnoses showed more interhospital transfers, more intensive care stays, higher scores of severity and treatment intensity, more often mechanical ventilation, a higher age, a higher number of diagnoses, a higher complexity level of the related cases and mortality. This observation could be made to a lesser degree for the female population. However, for the female population mortality was higher (stage III AKI 41.6%).Conclusion Using the POA flag, the results reflect the clinical situation of complications and comorbidities evolving unexpectedly. As our results show sex differences, that is, a lower morbidity of female patients for each stage, but a higher mortality, a deeper evaluation of the implied sex differences in staging of KD should follow.The general results confirm the necessity of a diagnosis-onset reporting in health statistics

In vitro experimental investigation of voice production

The process of human phonation involves a complex interaction between the physical domains of structural dynamics, fluid flow, and acoustic sound production and radiation. Given the high degree of nonlinearity of these processes, even small anatomical or physiological disturbances can significantly affect the voice signal. In the worst cases, patients can lose their voice and hence the normal mode of speech communication. To improve medical therapies and surgical techniques it is very important to understand better the physics of the human phonation process. Due to the limited experimental access to the human larynx, alternative strategies, including artificial vocal folds, have been developed. The following review gives an overview of experimental investigations of artificial vocal folds within the last 30 years. The models are sorted into three groups: static models, externally driven models, and self-oscillating models. The focus is on the different models of the human vocal folds and on the ways in which they have been applied

Case 1: (A) Flow structures at the outlet.

<p>The velocity magnitude is color-coded. (B) Velocity profile plots in sections A and B from (A). Contours of velocity components (color-coded) u_x (C) and u_z (D) at the outlet plane.</p