Experimental and theoretical study of free-free electron-helium scattering in a CO2 laser field

International audienceFree-free transitions during the scattering of electrons by helium in the presence of a linearly polarized CO2 laser field are investigated both experimentally and theoretically. Signals for laser-assisted scattering at 22 eV with absorption or emission of up to two photons are measured at scattering angles between 20° and 70°, and are compared to the values obtained from an 11-state R-matrix Floquet calculation and from the low-frequency approximation of Kroll and Watson. The two sets of theoretical results are found to be in very good agreement for the scattering geometries considered in the experiment. The order of magnitude of the experimental results is reproduced by calculations with intensities in the region of 107 W cm-2. Agreement is improved by averaging the theoretical results over the spatial distributions of the three beams as well as the temporal intensity profile of the laser pulse, and by allowing for some misalignment of the three beams in the experiment

Accelerate [website]

‘ACCELERATE: Accessible Immersive Learning for Art and Design’ bought together art and design lecturers, educational researchers, and learning technologists from the UK, Ireland, Poland, and Ukraine to reflect on the impact of COVID-19 on higher education teaching to explore new possibilities for pedagogy and digital innovation. The project focused on the potential transformative role of immersive technologies (augmented, virtual, and extended reality) in the teaching of art and design while recognising that many learners face significant challenges in engaging effectively with XR technologies: disabilities; complex personal circumstances; low quality devices; poor and unreliable internet access. This 2-year Erasmus + ‘Strategic Partnership’ (2021-23) had a simple but ambitious aim: to improve the teaching of art and design at higher education in a post-pandemic Europe through the development of innovative methodologies, tools, platforms, and resources for accessible immersive learning. Drawing on the spirit of practice-led creative innovation, ACCELERATE created a new prototype platform for accessible immersive teaching in art and design that aimed to democratise XR technology. The collaborative development of this immersive ecosystem—open-source, scalable, sustainable—as a gateway for art and design lecturers and students with little or no previous experience of XR technologies was informed by a considered evaluation of the impact of COVID-19 on art and design teaching at the partner universities, the co-drafting of a Methodological guide, and a standalone online training course for lecturers populated with teaching materials, including co-created case studies that draw on the shared expertise and perspectives of all the project partners. By engaging with the layered complexities of XR accessibility and immersive learning, ACCELERATE has the capacity to be genuinely pioneering in its pedagogical and technological outcomes and find new ways of engaging with art and design students from disadvantaged and underrepresented groups

R-matrix Floquet theory for laser-assisted electron-atom scattering

A new version of the R-matrix Floquet theory for laser-assisted electron-atom scattering is presented. The theory is non-perturbative and applicable to a non-relativistic many-electron atom or ion in a homogeneous linearly polarized field. It is based on the use of channel functions built from field-dressed target states, which greatly simplifies the general formalism.Comment: 18 pages, LaTeX2e, submitted to J.Phys.

Inventory of Behaviours - What conditions (cultural, sociological, economic, political) shape artists’ behaviours, and how can they help us to rethink the ways in which we work, teach, and learn?

What conditions (cultural, sociological, economic, political) shape artists’ behaviours, and how can they help us to rethink the ways in which we work, teach and learn? IOB was initiated in 2017 to investigate the largely unseen and undiscussed behaviours, embodied tacit knowledge, that surround the making of art. The lead artists of this evolving artwork collected over 400 artists' instructions that document the behaviours, preparations, patterns, neuroses, and procrastinations of artists when they are not actively creating. These behaviours have formed the basis for a series of events in which art students and members of the public have enacted these behaviours in a gallery setting (Tate Modern). Artists and expert witnesses from a range of disciplines, including ethnography, physics, and neuroscience, observed events as they unfolded and interviewed participants, presenting their findings during closing debrief seminars. IOB research has illuminated the fundamental need artists have to engage in peripheral behaviours – to pause, to linger, to look away – as a means of maintaining their creative resources and their capacity to make art. Employing practice-led research methods, the project team asks how these behaviours, that are so crucial to artists’ continued creativity and wellbeing, might be of benefit to others. This project sits under MPF: An international network of transdisciplinary, practice-based researchers dedicated to querying our positions and agencies as artist-teachers

Elbow

The Elbow, the part of the human body that a blind or partially sighted person takes hold of, four fingers on the inside, thumb on the outside; holding with a firm grip to assist them with navigation. It is a common guiding technique linking two people into an unfamiliar choreography. In the summer of 2015 C&C Gallery hosted an innovative residency programme, transforming the gallery space into a dynamic studio environment in order to respond to ideas surrounding the condition of blindness. During this time eight artists variously came and went, engaging with a whole repertoire of processes, from casting to laser scanning, leaving a variety of traces of their activities. Much of the work, arrived at through a collaborative approach has sought to obliquely cast a shadow across the subject, remaining open towards the process of making, and the work remains in a state of uncertainty even at the time of writing. During a workshop in the space hosted by John Dickinson-Lilley, the artists wore blind glasses and stumbled rather pathetically around the gallery and the local high street, feeling unsure, insecure and inept, grounded only by the feeling of the floor beneath ones feet and ones fingers upon a companions elbow. Within the space; chalk lines, floor to ceiling columns and laser scanning targets have created an installation for measurement, where diverse material usage- including borax, expanding foam and cat litter humorously confound expectation

Chew

Chew is a series of playful interventions involving multi-sensory, participatory approaches that were interspersed throughout the session ‘Distracted Pedagogy' at the conference. The interventions encourage focus to oscillate from the mind to the body and from thought to action. The interventions draw attention to materials and bring ‘process’ into the space of theory through embodied cognition. Chew aims to tackle the impact of material processes on pedagogical practices; developing research through embodied learning and critical methodologies in relation to subversion, diversion and repetition. Chew asks whether material engagement can help to divert passive thinking into research. It aims to provide a space in which material can draw attention to the individual’s sensual, intellectual, and subconscious thinking through embodiment, subversion, diversion and repetitive actions. It involves four x 3-minute prompts of multi-sensory approaches that are designed to encourage focus to shift from the mind to the body, and from thought to action. Participants are given gum to chew and Playdough to manipulate throughout the interventions. Chew highlights issues of student-centred learning within hybrid and material pedagogical methodologies. The activities allow a chewing through making. The interactions are intended to enable a material processing of theory; a constant oscillation between making and language

Diabetic Retinopathy in Newly Diagnosed Subjects With Type 2 Diabetes Mellitus: Contribution of β-Cell Function

Purpose: The association of hyperglycemia and diabetic retinopathy (DR) in established type 2 diabetes mellitus (T2DM) subjects is well accepted. However, the association between β-cell responsiveness and insulin sensitivity leading to fasting and postprandial hyperglycemia with DR in newly diagnosed treatment-naïve T2DM subjects remain unreported. Methods: A total of 544 newly diagnosed treatment-naïve T2DM subjects were screened for DR (digital photography) and underwent a standardized meal tolerance test. Serial plasma glucose and insulin levels were measured, and fasting (M0) and postprandial β-cell responsiveness calculated Calculating Pancreatic Response Program along with homeostasis model assessment-β cell function (HOMA-B) and HOMA-Insulin Sensitivity. A subgroup of 201 subjects also underwent a frequently sampled IV glucose tolerance test and the acute insulin response to glucose, insulin sensitivity, and glucose effectiveness (SG) estimated (MINMOD model). Results: A total of 16.5% (90) subjects had DR at diagnosis. Subjects with DR had significantly reduced M0, HOMA-B and SG leading to higher fasting and postprandial (2 hour) glucose and significantly lower fasting and postprandial (2 hour) insulin. Factors independently associated with DR in multivariate logistic regression analysis were M0, HOMA-B, and SG with fasting and postprandial (2 hour) glucose and insulin. There was no statistical difference in glycated hemoglobin, systolic blood pressure, acute insulin response to glucose, and insulin sensitivity between those with or without DR. Principal Conclusions: In this cohort of newly diagnosed T2DM subjects, DR is associated with reduced β-cell responsiveness, resulting from β-cell failure rather than insulin resistance, leading to fasting and postprandial hyperglycemia and hypoinsulinemi

Metabolomic, hormonal and physiological responses to hypoglycemia versus euglycemia during exercise in adults with type 1 diabetes

Introduction This study sought to compare the metabolomic, hormonal and physiological responses to hypoglycemia versus euglycemia during exercise in adults with type 1 diabetes (T1D).Research design and methods Thirteen individuals with T1D (hemoglobin; 7.0%±1.3% (52.6±13.9 mmol/mol), age; 36±15 years, duration diabetes; 15±12 years) performed a maximum of 45 min submaximal exercise (60%±6% V̇O2max). Retrospectively identified exercise sessions that ended in hypoglycemia ((HypoEx) blood glucose (BG)≤3.9 mmol/L) were compared against a participant-matched euglycemic condition ((EuEx) BG≥4.0, BG≤10.0 mmol/L). Samples were compared for detailed physiological and hormonal parameters as well as metabolically profiled via large scale targeted ultra-high-performance liquid chromatography coupled to tandem mass spectrometry. Data were assessed using univariate and multivariate analysis techniques with false discovery rate adjustment. Significant results were considered at p≤0.05.Results Cardiorespiratory and counterregulatory hormone responses, whole-body fuel use and perception of fatigue during exercise were similar under conditions of hypoglycemia and euglycemia (BG 3.5±0.3 vs 5.8±1.1 mmol/L, respectively p<0.001). HypoEx was associated with greater adenosine salvage pathway activity (5’-methylthioadenosine, p=0.023 and higher cysteine and methionine metabolism), increased utilization of glucogenic amino acids (glutamine, p=0.021, alanine, aspartate and glutamate metabolism and homoserine/threonine, p=0.045) and evidence of enhanced β-oxidation (lower carnitine p<0.001, higher long-chain acylcarnitines).Conclusions Exposure to acute hypoglycemia during exercise potentiates alterations in subclinical indices of metabolic stress at the level of the metabolome. However, the physiological responses induced by dynamic physical exercise may mask the symptomatic recognition of mild hypoglycemia during exercise in people with T1D, a potential clinical safety concern that reinforces the need for diligent glucose management

Comparison of the effects of three insulinotropic drugs on plasma insulin levels after a standard meal

WSTĘP. Porównanie działania repaglinidu, glipizydu i glibenklamidu na wydzielanie insuliny i glukozy po posiłku próbnym zawierającym 500 kcal. MATERIAŁ I METODY. Do krzyżowej, randomizowanej, podwójnie ślepej próby zakwalifikowano 12 pacjentów z wczesną cukrzycą typu 2 (średnia wartość HbA1c 6,1%) oraz 12 osób jako grupę kontrolną. Chorzy losowo otrzymali placebo, 2 mg repaglinidu, 5 mg glipizydu i 5 mg glibenklamidu. Leki podawano po wzorcowym posiłku próbnym, zawierającym 500 kcal. Badania kolejnych leków wykonywano po okresie wydalania poprzedniego z organizmu (7&#8211;12 dni). WYNIKI. Wszystkie trzy leki miały jednakowy wpływ na całkowite posiłkowe wydzielanie insuliny (pole pod krzywą [AUC, area under the curve] -15-240 min). Zauważono jednak wyraźne różnice we wczesnym wydzielaniu insuliny (AUC -15-30 min): u badanych bez cukrzycy zarówno repaglinid, jak i glipizyd zwiększały wydzielanie insuliny odpowiednio o około 61 i 34% w porównaniu z placebo. Wśród chorych na cukrzycę różnica ta wynosiła odpowiednio 37 i 47%. W obu grupach stwierdzono istotną różnicę między glipizydem a glibenklamidem, natomiast repaglinid był skuteczniejszy niż glibenklamid tylko wśród zdrowych pacjentów bez cukrzycy. Wszystkie leki skutecznie obniżały całkowite stężenie glukozy AUC u chorych na cukrzycę i bez niej. Jednak wśród badanych bez cukrzycy repaglinid okazał się znamiennie skuteczniejszy niż glibenklamid. Różnicy takiej nie stwierdzono u chorych na cukrzycę, prawdopodobnie ze względu na częstsze występowanie insulinooporności w tej grupie. WNIOSKI. Repaglinid i glipizyd, ale nie glibenklamid, znacząco poprawiły wczesne wydzielanie insuliny po standardowym posiłku, zarówno wśród badanych bez cukrzycy, jak i wśród chorych na cukrzycę z zachowaną funkcją komórek b trzustki.INTRODUCTION. To compare the effects of repaglinide, glipizide, and glibenclamide on insulin secretion and postprandial glucose after a single standard 500-kcal test meal. MATERIAL AND METHODS. A total of 12 type 2 diabetic patients with early diabetes (mean HbA1c of 6.1%) and 12 matched control subjects were enrolled in this randomized, double-blind, crossover trial. Subjects received placebo, 2 mg repaglinide, 5 mg glipizide, and 5 mg glibenclamide in a random fashion during the trial. Administration of each drug was followed by a single standard 500-kcal test meal. A washout period of 7&#8211;12 days existed between the four study visits. RESULTS. All three drugs were equally effective on the total prandial insulin secretion (area under the curve [AUC] &#8211;15 to 240 min). However, clear differences were noted in the early insulin secretion (AUC &#8211;15 to 30 min); both repaglinide and glipizide increased secretion in nondiabetic subjects by ~61 and 34%, respectively, compared with placebo. In the diabetic patients, the difference versus placebo was 37 and 47%, respectively. The difference between glipizide and glibenclamide reached significance in both groups of subjects, whereas repaglinide was more effective than glibenclamide only in the healthy nondiabetic subject group. All three drugs were effective in decreasing total glucose AUC in the nondiabetic and diabetic population. In the nondiabetic subjects, however, repaglinide was significantly more effective than glibenclamide. The differences disappeared in the diabetic subjects, probably as a result of increased prevalence of insulin resistance in this group. CONCLUSIONS. Repaglinide and glipizide but not glibenclamide significantly enhanced the early insulin secretion in both nondiabetic and diabetic subjects with preserved b-cell function after a single standard meal