Dust particle charge in plasma with ion flow and electron depletion

The charge of micrometer-sized dust particles suspended in plasma above the powered electrode of radio-frequency (RF) discharges is studied. Using a self-consistent fluid model, the plasma profiles above the electrode are calculated and the electron depletion towards the electrode, as well as the increasing flow speed of ions towards the electrode, are considered in the calculation of the dust particle floating potential. The results are compared with those reported in literature and the importance of the spatial dust charge variation is investigated

Glow and dust in plasma boundaries

The sheath region is probed in different complex plasma experiments using dust particles in addition to measurement of the optical emission originating from the plasma. The local maximum in optical emission coincides with the breaking of quasi-neutrality at the sheath boundary as indicated by the vertical force profile reconstructed from dust particle trajectories, as well as by the local onset of dust density waves in high density dust clouds suspended in a dielectric box

Determination of the levitation limits of dust particles within the sheath in complex plasma experiments

Experiments are performed in which dust particles are levitated at varying heights above the powered electrode in a RF plasma discharge by changing the discharge power. The trajectories of particles dropped from the top of the discharge chamber are used to reconstruct the vertical electric force acting on the particles. The resulting data, together with the results from a selfconsistent fluid model, are used to determine the lower levitation limit for dust particles in the discharge and the approximate height above the lower electrode where quasineutrality is attained, locating the sheath edge. These results are then compared with current sheath models. It is also shown that particles levitated within a few electron Debye lengths of the sheath edge are located outside the linearly increasing portion of the electric field

One-dimensional vertical dust strings in a glass box

The oscillation spectrum of a one-dimensional vertical dust string formed inside a glass box on top of the lower electrode in a GEC reference cell was studied. A mechanism for creating a single vertical dust string is described. It is shown that the oscillation amplitudes, resonance frequencies, damping coefficients, and oscillation phases of the dust particles separate into two distinct groups. One group exhibits low damping coefficients, increasing amplitudes and decreasing resonance frequencies for dust particles closer to the lower electrode. The other group shows high damping coefficients but anomalous resonance frequencies and amplitudes. At low oscillation frequencies, the two groups are also separated by a {\pi}-phase difference. One possible cause for the difference in behavior between the two groups is discussed

Crystallization dynamics of a single layer complex plasma

We report a series of complex (dusty) plasma experiments, aimed at the study of the detailed time evolution of the re-crystallisation process following a rapid quench of a two dimensional dust liquid. The experiments were accompanied by large-scale (million particle) molecular dynamics simulations, assuming Yukawa type inter-particle interaction. Both experiment and simulation show a $\propto t^\alpha$ (power law) dependence of the linear crystallite domain size as measured by the bond-order correlation length, translational correlation length, dislocation (defect) density, and a direct size measurement algorithm. The results show two stages of order formation: on short time-scales individual particle motion dominates; this is a fast process characterized by $\alpha=0.93\pm0.1$. At longer time-scales, small crystallites undergo collective rearrangement, merging into bigger ones, resulting in a smaller exponent $\alpha=0.38\pm0.06$.Comment: 4 pages, 3 figures. Submitted to PR

Group-based pulmonary telerehabilitation is feasible, safe, beneficial and well-received in patients that have been hospitalised with Covid-19

Introduction Covid-19 has caused worldwide mass hospitalisation. The need for multi-disciplinary post-hospitalisation rehabilitation is becoming increasingly apparent and telerehabilitation has been endorsed. The aim of study was to investigate the feasibility and efficacy of pulmonary telerehabilitation for Covid-19 survivors.Methods A single centre, mixed-methods, fast-track (wait-list), randomised controlled trial of telerehabilitation for patients who have been hospitalised with Covid-19.Participants Forty patients discharged from two University Teaching Hospitals in the North of England. Interventions: Telerehabilitation consisted of twelve exercise classes, six education events and opportunity for peer support. Patients commenced telerehabilitation 14 days after randomisation in the fast-track group and 56 days after randomisation in the wait-list group.Outcome measures and results Descriptive and statistical improvements were noted is several clinical outcome measures. Exercise capacity increased from a median (Q1–Q3) 20 (14–24) sit-to-stand repetitions in one-minute at baseline to 25 (24–30) post-telerehabilitation. Breathlessness rated using the MRC changed from 3.5 (3–4) at baseline to 2 (1.5–3) post-telerehabilitation, with additional favourable outcomes noted in respiratory symptoms measured using numerical rating scales and visual analogue scales (VAS). Quality of life measured using the EQ-VAS improved from 55 (60–70) units at baseline to 70 (55–80) units following telerehabilitation. Improvements in fatigue (FACIT-F) and mood (HADS-D) were also observed. Natural recovery was observed in the wait-list group prior to receiving telerehabilitation, however, improvements were accelerated by early telerehabilitation in the fast-track group.Conclusions We have shown that group-based telerehabilitation is feasible, safe, beneficial and well-received in this population

Inverse dynamics modelling of upper-limb tremor, with cross-correlation analysis

A method to characterise upper-limb tremor using inverse dynamics modelling in combination with cross-correlation analyses is presented. A 15 degree-of-freedom inverse dynamics model is used to estimate the joint torques required to produce the measured limb motion, given a set of estimated inertial properties for the body segments. The magnitudes of the estimated torques are useful when assessing patients or evaluating possible intervention methods. The cross-correlation of the estimated joint torques is proposed to gain insight into how tremor in one limb segment interacts with tremor in another. The method is demonstrated using data from a single patient presenting intention tremor because of multiple sclerosis. It is shown that the inertial properties of the body segments can be estimated with sufficient accuracy using only the patient's height and weight as a priori knowledge, which ensures the method's practicality and transferability to clinical use. By providing a more detailed, objective characterisation of patient-specific tremor properties, the method is expected to improve the selection, design and assessment of treatment options on an individual basis

Telerehabilitation for patients who have been hospitalised with covid-19: a qualitative study

PurposeThe aim of this qualitative study was to explore the views of participants of a group-based, supervised, telerehabilitation programme, following discharge from hospital with Covid-19. This study was part of a single-centre, fast-track (wait-list), randomised, mixed-methods, feasibility trial of telerehabilitation (Registration: Clinicaltrials.gov reference:285205).MethodsSemi-structured interviews were conducted over a virtual teleconference platform with 10 participants who took part in a telerehabilitation programme following Covid-19 after discharge from an acute hospital. Data were transcribed verbatim and analysed using thematic analysis.ResultsFive themes were important from the participant perspective: telerehabilitation programme as part of the Covid-19 journey; the telerehabilitation programme design and delivery; peer aspects; the role of the instructor; and the role of technology and online delivery.ConclusionsOverall, the telerehabilitation programme was a positive experience for participants. The instructors were central to this positive view as was the group nature of the programme. The group aspect was particularly important in supporting the broader perceived wellbeing gains, such as the sense of enjoyment and reduced social isolation. Several participants would have liked to have continued with the exercises beyond the six-week intervention indicating that the programme could be a way to help people sustain a physically active lifestyle.IMPLICATIONS FOR REHABILITATIONParticipants who were recovering from Covid-19 following hospital admission perceived the telerehabilitation to be a positive experience overall.The group aspect of the telerehabilitation programme was important in supporting the broader perceived wellbeing gains such as the sense of enjoyment and reduced social isolation.Telerehabilitation programmes for Covid-19 may need to include pathways for participants to continue to engage in exercise beyond the time-limited six-week intervention to support ongoing self-management

Examining the Polymorphisms in the Hypoxia Pathway Genes in Relation to Outcome in Colorectal Cancer

Introduction Colorectal cancer is a common malignancy. Identification of genetic prognostic markers may help prognostic estimations in colorectal cancer. Genes that regulate response to hypoxia and other genes that are regulated under the hypoxic conditions have been shown to play roles in cancer progression. In this study, we hypothesized that genetic variations in the hypoxia pathway genes were associated with the risk of outcome in colorectal cancer patients. Methods This study was performed in two phases. In the first phase, 49 SNPs from six hypoxia pathway genes (HIF1A, HIF1B, HIF2A, LOX, MIF and CXCL12) in 272 colorectal cancer patients were analyzed. In the second phase, 77 SNPs from seven hypoxia pathway genes (HIF1A, HIF1B, HIF2A, HIF2B, HIF3A, LOX and CXCL12) were analyzed in an additional cohort of 535 patients. Kaplan Meier, Cox univariate and multivariable regression analyses were performed to analyze the relationship between the SNPs and overall survival (OS), disease free survival (DFS) or disease specific survival (DSS). Since this was a hypothesis-generating study, no correction for multiple testing was applied. Results In phase I, one SNP (HIF2A rs11125070) was found to be associated with DFS in multivariable analysis; yet association of a proxy polymorphism (HIF2A rs4953342) was not detected in the phase II patient cohort. In phase II, associations of two SNPs (HIF2A rs4953352 and HIF2B rs12593988) were significant in both OS and DFS multivariable analyses. However, association of HIF2A rs4953352 was not replicated in the phase I cohort using a proxy SNP (HIF2A rs6706003). Conclusion Overall, our study did not find a convincing evidence of association of the investigated polymorphisms with the disease outcomes in colorectal cance