4,771 research outputs found
Electrolytic lesions within central complex neuropils of the cockroach brain affect negotiation of barriers
Animals must negotiate obstacles in their path in order to successfully function within natural environments. These actions require transitions from walking to other behaviors, many of which are more involved than simple reflexes. For these behaviors to be successful, insects must evaluate objects in their path and then use that information to change posture or re-direct leg movements. Some of this control may occur within a region of the brain known as the central complex (CC). We used discrete electrolytic lesions to examine the role of certain sub-regions of the CC in various obstacle negotiation behaviors. We found that cockroaches with lesions to the protocerebral bridge (PB) and ellipsoid body (EB) exhibit abnormalities in turning and dealing with shelf-like objects; whereas, individuals with lesions to the fan-shaped body (FB) and lateral accessory lobe (LAL), exhibit abnormalities of those behaviors as well as climbing over blocks and up walls to a horizontal plane. Abnormalities in block climbing include decreased success rate, changes in climbing strategy, and delayed response to the block. Increases in these abnormal behaviors were significant in individuals with lesions to the FB and LAL. Although turning abnormalities are present in individuals with lesions to the LAL, EB and the lateral region of the FB, there are some differences in how these deficits present. For instance, the turning deficits seen in individuals with lateral FB lesions only occurred when turning in the direction opposite to the side of the brain on which the lesion occurred. By contrast, individuals with lesions to the EB and LAL exhibited turning abnormalities in both directions. Lesions in the medial region of the FB did not result in directional turning deficits, but in abnormalities in block climbing
Numerical computation of an Evans function for travelling waves
We demonstrate a geometrically inspired technique for computing Evans
functions for the linearised operators about travelling waves. Using the
examples of the F-KPP equation and a Keller-Segel model of bacterial
chemotaxis, we produce an Evans function which is computable through several
orders of magnitude in the spectral parameter and show how such a function can
naturally be extended into the continuous spectrum. In both examples, we use
this function to numerically verify the absence of eigenvalues in a large
region of the right half of the spectral plane. We also include a new proof of
spectral stability in the appropriate weighted space of travelling waves of
speed in the F-KPP equation.Comment: 37 pages, 11 figure
“If you can’t see a dilemma in this situation you should probably regard it as a warning”. A metasynthesis and theoretical modeling of general practitioners’ opioid prescription experiences in primary care.
Background: The prescribing of opioids has increased internationally in developed countries in recent decades within primary and secondary care.1 The majority of patients with chronic non-malignant pain (CNMP) are managed by their GP.2 Recent qualitative studies have examined the issue of opioid prescribing for chronic non-malignant pain (CNMP) from a GP viewpoint. Several factors have been reported to influence the prescribing of opioids for CNMP including aetiology of pain condition, co-morbidities, access to specialised care, history of drug abuse and professional scrutiny. We require a better understanding of problems GP’s face when making opioid prescribing decisions, interventions to provide better supports in the prescribing of opioids for CNMP. The aim of this study is to identify and synthesize the qualitative literature describing the factors influencing the nature and extent of opioid prescribing in CNMP in primary care. A theoretical model is then proposed which seeks to explain the relationship between factors influencing prescribing of opioids for CNMP by GPs. Methods: MEDLINE, Embase, PsychINFO, Cochrane Database, International Pharmaceutical Abstracts, Database of Abstracts of Reviews of Effects, CINAHL and Web of Science were systematically searched from January 1986- Feb 2018. Two reviewers independently screened titles and abstracts. Studies were excluded from the review if they were non-English language, theoretical or methodological articles, policy documents, conference abstracts or presentations, as where quotations were not clearly attributed to GPs participating in the study. The reviewers then independently assessed the full text of the articles using the Critical Appraisal Skills Programme (CASP) tool for qualitative research. The papers were coded by two researcher and these codes organised using Thematic Network Analysis. Basis themes were defined initially, organising themes were then developed followed by global themes which summarised the key theories emerging from the articles. Finally, a theoretical model was derived by the researchers using the global themes to explain the interplay between factors influencing opioid prescribing decisions. Results: From 7020 records, 18 full text papers were assessed, and 13 studies included in the synthesis; 9 were from USA, 3 from UK and 1 from Sweden. Seven organising themes were identified including trust and mistrust, the importance of aetiology, monitoring of prescription use, physical, psychological and societal harm, consultation variables, inadequate pain management, stigma and stereotypes and system barriers to effective and safe prescribing such as limited access to specialist care or support from allied healthcare professionals in primary care. Four global themes emerged;suspicion, risk, agreement and encompassing systems level factors. These global themes are inter-related and capture the complex decision-making processes underlying the opioid prescribing whereby the physician both consciously and subconsciously quantifies the risk-benefit relationship associated with initiating or continuing an opioid prescription. Conclusion: Prescribing of opioids for CNMP is influenced by a myriad of factors. Rather, than a simple risk-benefit view of the process, it is more useful to view this as a dynamic process in which unique considerations such as the morality of opioid use exert an effect. Recognising the inherent complexity of the process and the limitations of healthcare systems, guidelines directed at GPs should offer more nuanced recommendations on managing opioid prescribing consultations in primary care
Absence of the Rashba effect in undoped asymmetric quantum wells
To an electron moving in free space an electric field appears as a magnetic
field which interacts with and can reorient the electron spin. In semiconductor
quantum wells this spin-orbit interaction seems to offer the possibility of
gate-voltage control in spintronic devices but, as the electrons are subject to
both ion-core and macroscopic structural potentials, this over-simple picture
has lead to intense debate. For example, an externally applied field acting on
the envelope of the electron wavefunction determined by the macroscopic
potential, underestimates the experimentally observed spin-orbit field by many
orders of magnitude while the Ehrenfest theorem suggests that it should
actually be zero. Here we challenge, both experimentally and theoretically, the
widely held belief that any inversion asymmetry of the macroscopic potential,
not only electric field, will produce a significant spin-orbit field for
electrons. This conclusion has far-reaching consequences for the design of
spintronic devices while illuminating important fundamental physics.Comment: 7 pages, 5 fig
A CASE STUDY ON THE EFFECTS OF THE UPPER ARM DEFINITION ON SHOULDER AND ELBOW KINEMATICS DURING THE BADMINTON SMASH
The aim of this case study was to identify the effect of the upper arm definition on shoulder and elbow kinematics during the badminton smash. A method was proposed that corrects the false external rotation when using the shoulder-elbow-wrist plane based on the carrying angle (ISB-2C) and compared to ISB recommendations for defining the upper arm (ISB-1 and ISB-2). Differences were found in shoulder and elbow kinematics, in particular angular velocities. Both magnitude and the time history of the angular velocity were affected. In particular, use of the medial and lateral epicondyles was unable to detect a reasonable signal for pronation/supination. ISB-2C reduces some of the problems associated with ISB-1 and ISB-2 e.g. soft-tissue artifact, proximity of medial and lateral epicondyles to the humeral longitudinal axis and false external rotation caused by the carrying angle
Polymeric IgA and immune complex concentrations in IgA-related renal disease
Polymeric IgA and immune complex concentrations in IgA-related renal disease. Polymeric IgA (PIgA) and immune complex concentrations in IgA-related renal disease were measured in cross sectional and longitudinal studies to establish the relationship between these parameters and both mucosal infection and renal dysfunction. These studies were performed in 50 patients with IgA nephropathy (IgAN), 17 patients with Henoch Schönlein purpura nephritis (HSPN), 11 control patients with IgA negative, diffuse mesangial proliferative glomerulonephritis (DMPGN) and 50 healthy controls. Total PIgA (PIgAT) and PIgA subclass concentrations were measured using a secretory component binding enzyme immunoassay and isotype specific immune complex concentrations were measured using conglutinin (K) binding immunoassays. In cross sectional studies patients with IgAN were found to have increased concentrations of PIgAT, PIgA1, K-IgA1 and K-IgA2 compared to controls. In the longitudinal studies controls and patients had significant increases in PIgAT and PIgA1 concentrations during infection. However, in patients with IgAN, the increases were greater, persisted for longer, and PIgA2 concentrations were also increased. K-IgA1 and K-IgA2 concentrations increased significantly during episodes of infection in IgAN patients in contrast to controls. Patients with HSPN had results similar to those of IgAN patients. No significant correlation was found between PIgA or K-IgA concentrations, and either serum creatinine concentrations or the degree of hematuria. The results indicate that patients with IgA-related renal disease have abnormal regulation of PIgA and immune complexed IgA, and that these abnormalities are exaggerated during mucosal infection
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