Jamming of frictional spheres and random loose packing

The role of friction coefficient, $\mu$, on the jamming properties of disordered, particle packings is studied using computer simulations. Compressed, soft-sphere packings are brought towards the jamming transition - the point where a packing loses mechanical stability - by decreasing the packing fraction. The values of the packing fraction at the jamming transition, $\phi^{\mu}_{c}$, gradually decrease from the random close packing point for zero friction, to a value coincident with random loose packing as the friction coefficient is increased over several orders of magnitude. This is accompanied by a decrease in the coordination number at the jamming transition, $z^{\mu}_{c}$, which varies from approximately six to four with increasing friction. Universal power law scaling is observed in the pressure and coordination number as a function of distance from the generalised, friction-dependent jamming point. Various power laws are also reported between the $\phi^{\mu}_{\rm c}$, $z^{\mu}_{\rm c}$, and $\mu$. Dependence on preparation history of the packings is also investigated.Comment: Published in Soft Matter themed issue on Granular and jammed materials (2010

The late response of rat subependymal zone stem and progenitor cells to stroke is restricted to directly affected areas of their niche

AbstractIschaemia leads to increased proliferation of progenitors in the subependymal zone (SEZ) neurogenic niche of the adult brain and to generation and migration of newborn neurons. Here we investigated the spatiotemporal characteristics of the mitotic activity of adult neural stem and progenitor cells in the SEZ during the sub-acute and chronic post-ischaemic phases. Ischaemia was induced by performing a 1h unilateral middle cerebral artery occlusion (MCAO) and tissue was collected 4/5weeks and 1year after the insult. Neural stem cells (NSCs) responded differently from their downstream progenitors to MCAO, with NSCs being activated only transiently whilst progenitors remain activated even at 1year post-injury. Importantly, mitotic activation was observed only in the affected areas of the niche and specifically in the dorsal half of the SEZ. Analysis of the topography of mitoses, in relation to the anatomy of the lesion and to the position of ependymal cells and blood vessels, suggested an interplay between lesion-derived recruiting signals and the local signals that normally control proliferation in the chronic post-ischaemic phase

On-line vs. On-site Dance for People with Parkinson’s Disease: An Evaluation Study

Background: Dance for people with Parkinson’s disease (PD) has received much attention with studies showing its benefits in terms of physical and psychological changes. As people with PD experience barriers to participate in on-site activities, home-based telehealth interventions are becoming increasingly popular. This study examined the differences between digital and on-site dance for people with PD. Methods: This evaluation study used a secondary qualitative analysis of focus group data from six participants with PD who had experience of digital and on-site dance, as well as two interviews with the dance teacher of both dance formats for people with PD. Thematic analysis was used to analyze the data. Results: Both the dancers and the dance teacher reported how the social and artistic aspects of on-site dance are not present to the same degree in digital dance. These aspects were experienced as important for acceptance of oneself and PD. Conclusions: This evaluation study demonstrates that the social and artistic aspects of dance are not experienced to the same degree within both types of dance. As these aspects were closely connected to acceptance of oneself and PD, this study encourages future efforts to focus on the social and artistic constructs within digital dance.Godkänd;2023;Nivå 0;2023-12-20 (marisr);Full text license: CC BY-NC</p

Digital Dance for People With Parkinson's Disease During the COVID-19 Pandemic : A Feasibility Study

Background: Dance as a treatment to support physical, cognitive and emotional functioning, has gained increased acceptance as a healthcare intervention for people with Parkinson's Disease (PD). The impact of the COVID-19 pandemic has been far reaching with devastating effects for at-risk populations. To find alternative and safe treatment delivery options during the pandemic has been of utmost importance. The purpose of this mixed-methods study was to evaluate the feasibility and the experience of digital dance for people with PD (Dance for PD©) and to examine change in self-reported quality of life, psychological health, subjective cognitive complaints and mental fatigue. Methods: 23 participants with PD (mean age 70) partook in 10-h weekly digital Dance for PD sessions. Feasibility outcome measures were assessed at post-test. Web-based questionnaires examining quality of life, subjective memory complaints, depression, anxiety and mental fatigue were administered at pre- and post-test. Moreover, nine participants partook in focus group discussions at post-test. Results: The results showed an acceptable feasibility to home-based digital Dance for PD, where 86% of the dance classes were completed, only minor negative side effects were reported (i.e., sore joints), and all experienced the dance classes as motivating and safe to do at home. The majority also reported positive effects on mood and physical functioning. The results from the questionnaires showed significant improvements in depressive symptoms (p = 0.006) and quality of life (p &lt; 0.001) at post-test. In the focus groups, participants indicated that digital dance was a beneficial and enjoyable activity with a strong added value during the COVID-19 pandemic. Nevertheless, they experienced that digital dance missed some important elements of live dance. Conclusions: This study showed that digital Dance for PD is feasible and holds promise as a viable and safe method to keep people with PD dancing even when physical meetings are not possible. Beyond the pandemic, digital dance could be applied to a wide variety of patient groups including rural populations and patients for whom transportation may not be feasible for practical or financial reasons. Trial Registration: Retrospectively registered at ClinicalTrials.gov on 25/06/2021 with the following registration number: NCT04942392

Evaluating a frontostriatal working-memory updating-training paradigm in Parkinson's disease : the iPARK trial, a double-blinded randomized controlled trial

Background: Cognitive decline and dementia are common in Parkinson's disease (PD). Cognitive deficits have been linked to the depletion of dopamine in the nigrostriatal pathway, but pharmacological treatments for PD have little evidence of improving or delaying cognitive decline. Therefore, exploring non-pharmacological treatment options is important. There have been some promising results of cognitive training interventions in PD, especially for improvements in working memory and executive functions. Yet, existing studies are often underpowered, lacking appropriate control condition, long term follow-up, a thorough description of the intervention and characteristics of the participants. Working memory updating training has previously shown to increase striatal activation in healthy young and old participants as well as dopaminergic neurotransmission in healthy young participants. In the light of dopamine dysfunction in PD, with negative effects on both motor and cognitive functions it is of interest to study if an impaired striatal system can be responsive to a non-invasive, non-pharmacological intervention. Methods and design: The iPARK trial is a double-blinded, randomized controlled trial with a parallel-group design that aims to recruit 80 patients with PD (during the period 02/2017-02/2023). Included patients need to have PD, Hoehn and Yahr staging I-III, be between 45 to 75 years of age and not have a diagnosis of dementia. All patients will undergo 30 sessions (6-8 weeks) of web-based cognitive training performed from home. The target intervention is a process-based training program targeting working memory updating. The placebo program is a low dose short-term memory program. A battery of neuropsychological tests and questionnaires will be performed before training, directly after training, and 16 weeks after training. Discussion: We expect that the iPARK trial will provide novel and clinically useful information on whether updating training is an effective cognitive training paradigm in PD. Further, it will hopefully contribute to a better understanding of cognitive function in PD and provide answers regarding cognitive plasticity as well as determining critical factors for a responsive striatal system

The Effects of Working Memory Updating Training in Parkinson’s Disease : A Feasibility and Single-Subject Study on Cognition, Movement and Functional Brain Response

In Parkinson’s disease (PD), the fronto-striatal network is involved in motor and cognitive symptoms. Working memory (WM) updating training engages this network in healthy populations, as observed by improved cognitive performance and increased striatal BOLD signal. This two-part study aimed to assess the feasibility of WM updating training in PD and measure change in cognition, movement and functional brain response in one individual with PD after WM updating training. A feasibility and single-subject (FL) study were performed in which patients with PD completed computerized WM updating training. The outcome measures were the pre-post changes in criterion and transfer cognitive tests; cognitive complaints; psychological health; movement kinematics; and task-related BOLD signal. Participants in the feasibility study showed improvements on the criterion tests at post-test. FL displayed the largest improvements on the criterion tests and smaller improvements on transfer tests. Furthermore, FL reported improved cognitive performance in everyday life. A shorter onset latency and smoother upper-limb goal-directed movements were measured at post-test, as well as increased activation within the striatum and decreased activation throughout the fronto-parietal WM network. This two-part study demonstrated that WM updating training is feasible to complete for PD patients and that change occurred in FL at post-test in the domains of cognition, movement and functional brain response

Developing and testing a mobile application for breastfeeding support: The Milky Way application

© 2020 Australian College of Midwives Background: Supporting women to continue breastfeeding is a global challenge. The Milky Way Program is an effective face to face intervention to increase breastfeeding rates up to six months postpartum. The sustainability and access to the Milky Way Program could be enhanced by transforming it into a mobile application allowing women to access relevant information from their own place at a convenient time. Aim: To explore the process of transforming the Milky Way Program into an acceptable and usable mobile health application. Method: Stakeholders including multidisciplinary researchers and end-users designed the application based on the Milky Way Program by using Persuasive System Design principles. A mixed-method approach was used in the development and evaluation process. Seven women were recruited through convenience sampling to pilot test the application. The women\u27s feedback was collected through an online survey six weeks after birth and individual interviews at four months postpartum. Findings: Women in the pilot study reported that the breastfeeding application was well designed, easy to use, interactive, reassuring and evidence-based with credible sources of information. Conclusion: The Persuasive System Design model combined with end-user engagement can feasibly inform the development of an acceptable and usable mobile health application for breastfeeding based on a proven clinical intervention. Further rigorous testing is required to evaluate the effectiveness of the application on breastfeeding initiation and duration