Theory of Suspension Segregation in Partially Filled Horizontal Rotating Cylinders

It is shown that a suspension of particles in a partially-filled, horizontal, rotating cylinder is linearly unstable towards axial segregation and an undulation of the free surface at large enough particle concentrations. Relying on the shear-induced diffusion of particles, concentration-dependent viscosity, and the existence of a free surface, our theory provides an explanation of the experiments of Tirumkudulu et al., Phys. Fluids 11, 507-509 (1999); ibid. 12, 1615 (2000).Comment: Accepted for publication in Phys Fluids (Lett) 10 pages, two eps figure

Pharmacokinetics of Octreotide in Patients With Cirrhosis and Portal Hypertension; Relationship Between the Plasma Levels of the Analogue and the Magnitude and Duration of the Reduction in Corrected Wedged Hepatic Venous Pressure

In healthy subjects octreotide is largely metabolised by the liver suggesting that the plasma half-life of the somatostatin analogue may be prolonged in patients with hepatic dysfunction. The aim of this study was therefore (a) to determine the pharmacokinetics of octreotide following its subcutaneous injection in 6 patients with cirrhosis and portal hypertension and (b) compare the magnitude and duration of the effects of intravenous administration of 250 μg somatostatin and 50 μg octreotide on corrected wedged hepatic venous pressure (WHVP) and to relate the findings to the plasma levels of the analogue 1h after administration in 13 patients with cirrhosis and portal hypertension. Following subcutaneous administration of 50 μg octreotide the circulating half life (range 2.4 to 4.79 h) was prolonged whereas the clearance (range 2.101 to 4.775 L/h) was decreased compared to healthy controls. Intravenous bolus administration of 25 μg somatostatin or 50 μg octreotide resulted in a reduction in WHVP of approximately the same magnitude and duration despite appreciable quantities of the analogue in the blood lh after administration (1944 ± 226 pg/ml). These results indicate that the circulating half-life of octreotide is prolonged in cirrhotics suggesting that the dosage regimens should be modified in such patients to avoid accumulation of the analogue in the blood which may result in undesirable side-effects or toxicity. Furthermore, since the magnitude and duration of the reduction in WHVP elicited by IV octreotide is similar to that obseved with somatostatin, the analogue, like the native hormone, must be administered by continuous IV infusion to produce a sustained response and hence a therapeutic effect in the management of acute variceal bleeding

The statistics of particle velocities in dense granular flows

We present measurements of the particle velocity distribution in the flow of granular material through vertical channels. Our study is confined to dense, slow flows where the material shears like a fluid only in thin layers adjacent to the walls, while a large core moves without continuous deformation, like a solid. We find the velocity distribution to be non-Gaussian, anisotropic, and to follow a power law at large velocities. Remarkably, the distribution is identical in the fluid-like and solid-like regions. The velocity variance is maximum at the core, defying predictions of hydrodynamic theories. We show evidence of spatially correlated motion, and propose a mechanism for the generation of fluctuational motion in the absence of shear.Comment: Submitted to Phys. Rev. Let

Depressive symptoms moderate functional connectivity within the emotional brain in chronic pain

Background Depressive symptoms are often comorbid with chronic pain. These conditions share aberrant emotion processing and regulation, as well as having common brain networks. However, the relationship between depressive symptoms and chronic pain and the effects on emotional brain function are unclear. Aims The present study aimed to disentangle the effects of chronic pain and depressive symptoms on functional connectivity between regions implicated in both these conditions. Method Twenty-six individuals with chronic pain (referred to as the pain group) and 32 healthy controls underwent resting-state functional magnetic resonance imaging and completed the Beck Depression Inventory. Main effects of group, depressive symptoms (total severity score) and their interaction on the functional connectivity of three seed regions (the left and right amygdalae and the medial prefrontal cortex; mPFC) with the rest of the brain were evaluated. In cases of significant interaction, moderation analyses were conducted. Results The group × depressive symptoms interaction was significantly associated with changes in connectivity between the right amygdala and the mPFC (family-wise error-corrected P-threshold (pFWEc = 0.008). In the moderation analysis, the pain group showed weaker connectivity between these regions at lower levels of depressive symptoms (P = 0.020), and stronger connectivity at higher levels of depressive symptoms (P = 0.003), compared with the healthy controls. In addition, the strength of connectivity decreased in the healthy controls (P = 0.005) and increased in the pain group (P = 0.014) as the severity of depressive symptoms increased. Conclusions Depressive symptoms moderate the impact of chronic pain on emotional brain function, with potential implications for the choice of treatment for chronic pain

A Novel Method of Determining Portal Systemic Shunting using Biodegradable 99TCm Labelled Albumin Microspheres

Portal systemic shunting (PSS) and portal pressure were measured in control rats and in animals with portal hypertension induced by partial portal vein ligation (PPVL). The portal pressure in rats with partial portal vein ligation (13.4 ± 0.5 mm.Hg.) was significantly higher (p < 0.005) than in the control group (9.6 ± 0.6 mm.Hg.). Portal systemic shunting measured by consecutive injections of radiolabelled methylene diphosphonate (MDP), a non-diffusable marker and albumin microspheres directly into the splenic pulp was significantly increased (P < 0.005) in the portal hypertensive animals (30.8 ± 2.5%) compared to sham operated rats (2.6 ± 1.5%). Similarly, in portal hypertensive rats portal systemic shunting measured by intrasplenic injections of radiolabelled cobalt microspheres (37.1 ± 3.9%) was significantly greater (p < 0.005) than in control animals. There was a good correlation and agreement (r = 00.97) between the two methods of measuring portal systemic shunting. However because the 99Tcm-albumin microspheres are biodegradable the method allows portal systemic shunting to be measured in man. Furthermore since the computer adjusts the baseline to zero after each determination of portal systemic shunting the methodology allows repeated measurements to be made

Evaluation of emotion-centric psychological interventions for chronic pain: protocol for a systematic review and meta-analysis

Introduction Chronic pain, defined as pain persisting longer than 3 months, is more than an unpleasant sensory experience. Persistent negative emotions and emotional comorbidities, such as depression and anxiety, plague people with chronic pain leading to worsening pain intensity and increasing disability. While cognitive-behavioural therapy (CBT) is the gold standard psychological treatment, recent evidence highlights that CBT lacks efficacy for the physical and emotional aspects of chronic pain. Increasingly, researchers are investigating emotion-centric psychological therapies. While treatment modalities vary, these interventions frequently target understanding emotions, and train individuals for an emotionally adaptive response. The aim of this systematic review and meta-analysis is to quantify the efficacy of emotion-centric interventions for the physical and emotional characteristics of chronic pain. Methods/analysis Electronic databases (EMBASE, PubMed, PsychINFO, Cochrane Central Register of Controlled Trials, CINAHL and Web of Science) will be systematically searched from inception to 28 April 2022 for randomised controlled trials. Studies that compare an emotion-centric intervention with another form of treatment or placebo/control for adults (≥18 years old) with chronic pain will be included. All treatment modes (eg, online or in-person), any duration and group-based or individual treatments will be included. Studies that do not investigate at least one emotion-centric treatment will be excluded. The primary outcome is pain intensity. Secondary outcomes include emotion dysregulation, depression, anxiety, affect, safety and intervention compliance. A quantitative synthesis using a random effects meta-analysis will be adopted. Risk of bias will be evaluated using Cochrane Risk of Bias V.2.0 with the certainty of evidence assessed according to Recommendation, Assessment, Development and Evaluation. Data permitting, subgroup analysis will be conducted for intervention type and pain condition. Ethics and dissemination Ethical approval is not required for this systematic review. Results may inform an efficacy study examining a new emotion-centric intervention for chronic pain. Dissemination will be through peer-reviewed publications and in conference presentations. PROSPERO registration number CRD42021266815

Internet-Delivered Dialectical Behavioral Therapy Skills Training for Chronic Pain: Protocol for a Randomized Controlled Trial

Background: Emotion dysregulation is key to the development and maintenance of chronic pain, feeding into a cycle of worsening pain and disability. Dialectical behavioral therapy (DBT), an evidence-based treatment for complex transdiagnostic conditions presenting with high emotion dysregulation, may be beneficial to manage and mitigate the emotional and sensory aspects of chronic pain. Increasingly, DBT skills training as a key component of standard DBT is being delivered as a stand-alone intervention without concurrent therapy to help develop skills for effective emotion regulation. A previous repeated-measure single-case trial investigating a novel technologically driven DBT skills training, internet-delivered DBT skills training for chronic pain (iDBT-Pain), revealed promising findings to improve both emotion dysregulation and pain intensity. Objective: This randomized controlled trial aims to examine the efficacy of iDBT-Pain in comparison with treatment as usual to reduce emotion dysregulation (primary outcome) for individuals with chronic pain after 9 weeks and at the 21-week follow-up. The secondary outcomes include pain intensity, pain interference, anxiety symptoms, depressive symptoms, perceived stress, posttraumatic stress, harm avoidance, social cognition, sleep quality, life satisfaction, and well-being. The trial also examines the acceptability of the iDBT-Pain intervention for future development and testing. Methods: A total of 48 people with chronic pain will be randomly assigned to 1 of 2 conditions: treatment and treatment as usual. Participants in the treatment condition will receive iDBT-Pain, consisting of 6 live web-based group sessions led by a DBT skills trainer and supervised by a registered psychologist and the iDBT-Pain app. Participants in the treatment-as-usual condition will not receive iDBT-Pain but will still access their usual medication and health interventions. We predict that iDBT-Pain will improve the primary outcome of emotion dysregulation and the secondary outcomes of pain intensity, pain interference, anxiety symptoms, depressive symptoms, perceived stress, harm avoidance, social cognition, sleep quality, life satisfaction, and well-being. A linear mixed model with random effects of individuals will be conducted to investigate the differences between the baseline, 9-week (primary end point), and 21-week (follow-up) assessments as a function of experimental condition. Results: Recruitment started in February 2023, and the clinical trial started in March 2023. Data collection for the final assessment is planned to be completed by July 2024. Conclusions: If our hypothesis is confirmed, our findings will contribute to the evidence for the efficacy and acceptability of a viable intervention that may be used by health care professionals for people with chronic pain. The results will add to the chronic pain literature to inform about the potential benefits of DBT skills training for chronic pain and will contribute evidence about technologically driven interventions

Emotion regulation skills-focused interventions for chronic pain: A systematic review and meta-analysis

Objectives: To investigate the effect of emotion regulation skills-focused (ERSF) interventions to reduce pain intensity and improve psychological outcomes for people with chronic pain and to narratively report on safety and intervention compliance. Methods: Six databases and four registries were searched for randomized controlled trials (RCTs) up to 29 April 2022. Risk of bias was evaluated using the Cochrane RoB 2.0 tool, and certainty of evidence was assessed according to the Grading, Assessment, Development and Evaluation (GRADE). Meta-analyses for eight studies (902 participants) assessed pain intensity (primary outcome), emotion regulation, affect, symptoms of depression and anxiety, and pain interference (secondary outcomes), at two time points when available, post-intervention (closest to intervention end) and follow-up (the first measurement after the post-intervention assessment). Results: Compared to TAU, pain intensity improved post-intervention (weighted mean difference [WMD] = −10.86; 95% confidence interval [CI] [−17.55, −2.56]) and at follow-up (WMD = −11.38; 95% CI [−13.55, −9.21]). Emotion regulation improved post-intervention (standard mean difference [SMD] = 0.57; 95% CI [0.14, 1.01]), and depressive symptoms improved at follow-up (SMD = −0.45; 95% CI [−0.66, −0.24]). Compared to active comparators, anxiety symptoms improved favouring the comparator post-intervention (SMD = 0.10; 95% CI [0.03, 0.18]), and compared to CBT, pain interference improved post-intervention (SMD = −0.37; 95% CI [−0.69, −0.04]). Certainty of evidence ranged from very low to moderate. Significance: The findings provide evidence that ERSF interventions reduce pain intensity for people with chronic pain compared to usual treatment. These interventions are at least as beneficial to reduce pain intensity as the current gold standard psychological intervention, CBT. However, the limited number of studies and certainty of evidence mean further high-quality RCTs are warranted. Additionally, further research is needed to identify whether ERSF interventions may be more beneficial for specific chronic pain conditions

The No Worries Trial: Efficacy of Online Dialectical Behaviour Therapy Skills Training for Chronic Pain (iDBT-Pain) Using a Single Case Experimental Design

Emotion dysregulation frequently co-occurs with chronic pain, which in turn leads to heightened emotional and physical suffering. This cycle of association has prompted a recommendation for psychological treatment of chronic pain to target mechanisms for emotion regulation. The current trial addressed this need by investigating a new internet-delivered treatment incorporating emotional skills training from dialectical behavioral therapy (DBT). Using a single-case experimental design that is suited to heterogeneous populations and can demonstrate efficacy with a small sample, three participants with chronic pain were recruited. Participants received four weeks of online DBT skills training (iDBT-Pain intervention) which incorporated one-on-one sessions over Zoom and a web app. Results revealed compelling evidence for the intervention on the primary outcome of emotion dysregulation and were promising for the secondary outcome of pain intensity. Improvement was also identified on pre-and post-measures of depression, coping behaviors, sleep problems, wellbeing, and harm avoidance, indicating that the intervention may positively influence other factors related to chronic pain. Overall, the trial provides preliminary efficacy for the intervention to improve chronic pain. However, we recommend further investigation of the iDBT-Pain intervention, either in single case trials, which when conducted with scientific rigor may be aggregated to derive nomothetic conclusions, or in a group-comparison trial to compare with usual modes of treatment. Perspective: This trial advances understanding of emotion-focused treatment for chronic pain and provides evidence for a viable new technological treatment. Importantly, as an internet-delivered approach, the iDBT-Pain intervention is accessible to those with restricted mobility and remote communities where there are often limited psychological services for people with chronic pain