Magnetic actuation of microparticles for mass transfer enhancement

The motion of magnetic microparticles (250μm diameter) in a circular microfluidic reactor with a diameter of 10 mm under time dependent magnetic field has been studied using CFD code COMSOL. The effect of actuation protocol on the local and average particle velocity has been investigated. The local Sh numbers were obtained as a function of angular particle position in the range of Re numbers between 0.05 and 10 while the particle velocity was changed over two orders of magnitude. Under time dependent magnetic field, the thickness of the boundary layer continuously changes which results in an increased mass transfer towards the particle surface under periodic particle velocity conditions as compared to steady state velocity conditions. A good agreement between numerical and experimental data has been observed

Does personality affect premating isolation between locally-adapted populations?

Background: One aspect of premating isolation between diverging, locally-adapted population pairs is female mate choice for resident over alien male phenotypes. Mating preferences often show considerable individual variation, and whether or not certain individuals are more likely to contribute to population interbreeding remains to be studied. In the Poecilia mexicana-species complex different ecotypes have adapted to hydrogen sulfide (H2S)-toxic springs, and females from adjacent non-sulfidic habitats prefer resident over sulfide-adapted males. We asked if consistent individual differences in behavioral tendencies (animal personality) predict the strength and direction of the mate choice component of premating isolation in this system. Results: We characterized focal females for their personality and found behavioral measures of ‘novel object exploration’, ‘boldness’ and ‘activity in an unknown area’ to be highly repeatable. Furthermore, the interaction term between our measures of exploration and boldness affected focal females’ strength of preference (SOP) for the resident male phenotype in dichotomous association preference tests. High exploration tendencies were coupled with stronger SOPs for resident over alien mating partners in bold, but not shy, females. Shy and/or little explorative females had an increased likelihood of preferring the non-resident phenotype and thus, are more likely to contribute to rare population hybridization. When we offered large vs. small conspecific stimulus males instead, less explorative females showed stronger preferences for large male body size. However, this effect disappeared when the size difference between the stimulus males was small. Conclusions: Our results suggest that personality affects female mate choice in a very nuanced fashion. Hence, population differences in the distribution of personality types could be facilitating or impeding reproductive isolation between diverging populations depending on the study system and the male trait(s) upon which females base their mating decisions, respectively

Magnetic actuation of catalytic microparticles for the enhancement of mass transfer rate in a flow reactor

The effect of periodic changes in particle velocity on mass transfer to the reacting surface of a magnetic particle with a diameter 225 μm in laminar flow has been investigated in a microfluidic reactor. The periodic particle motion in a fluid was investigated under a sinusoidal magnetic field generated by a quadrupole arrangement of electromagnets around the reactor. The effect of operating frequency of the rotating magnetic field, intensity of the magnetic field, and phase shift between the two sets of magnets on particle dynamics has been studied. Three particle motion modes have been observed depending on the frequency of the applied field. The mass transfer rate was estimated under steady velocity and variable velocity of the particle using a mass transfer correlation by Feng and Michaelides (2001). The validity of this correlation for the case of variable particle velocity has been confirmed with a 2D numerical model, describing actual hydrodynamics and mass transfer towards the particle surface. The mass transfer coefficient depends both on the mean particle velocity and the deviation of velocity from the mean value. The periodic movement with variable particle velocity reduces the mass transfer coefficient by 7.6% as compared to steady state motion with the same mean velocity

Palliative care for people with schizophrenia: A qualitative study of an under-serviced group in need

© 2018 The Author(s). Background: People with schizophrenia are at risk of receiving poorer end of life care than other patients. They are often undertreated, avoid treatment and are about half as likely to access palliative care. There are limited options for end of life care for this under-serviced group in need. This study aims to address the paucity of research by documenting possible need, experiences of health care service use and factors affecting palliative care use for people with schizophrenia who have advanced life limiting illness. Methods: Semi-structured interviews were undertaken with 16 experienced health professionals caring for people with schizophrenia in Western Australia. The interviews focussed on their perceptions and experiences of end of life care, their patients' unmet needs, palliative care options, and suggested services to support this vulnerable group and improve health care provision. The research used a qualitative design and thematic analyses. Results: The participants all advocated strongly for their patients and recognised their extreme vulnerability. They identified a range of challenges and unmet needs experienced by people with schizophrenia at the end of life including: illness factors such as the impact of schizophrenia on information processing and communication; social factors such as stigma, isolation and the absence of a carer; and health care factors such as late diagnosis, delayed access to care, and mismanagement in care. Four themes were organised into two domains with the first exploring the individual and social circumstances of people with schizophrenia, including the challenges they experience in the health care system. The second domain covers themes that discuss barriers and facilitators to people with schizophrenia receiving palliative care and key features in palliative care provision, including recognising declining health, communication and planning, and collaboration and capacity building in the broader health, mental health and palliative care sectors. Conclusions: To ensure people with schizophrenia are well supported at the end of life a model of palliative care is required that offers both specialised services and capacity building within the pre-existing health workforce. Resources are needed to address the stigma and lack of services faced by this vulnerable group