Non-paraxial Talbot effect in one-dimensional gratings with period comparable to the wavelength

The Talbot effect is a diffractive phenomenon which was found since its inception in the Gaussian optics, but when the period of the object is comparable with the wavelength is considered entering its non-paraxial regime. There, it has attracted interest for its applications related to the design of objects and their restorative effects posing in damaged gratings on this scale. In this contribution a study of this phenomenon at level non-paraxial (metaxial) is presented by using scalar diffraction theory in plane waves representation for periodic transversal fields. To this end, a one-dimensional amplitude grating of period p is used which is illuminated by a monochromatic plane wave of wavelength λ where p ranges between 1,5 λ and 4,2 λ.Fil: Arrieta, E.. Universidad Popular del Cesar; ColombiaFil: Bolognini, Nestor Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigaciones Ópticas. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigaciones Ópticas. Universidad Nacional de La Plata. Centro de Investigaciones Ópticas; ArgentinaFil: Torres, C.O.. Universidad Popular del Cesar; Colombi

The pharmacology and function of receptors for short-chain fatty acids

Despite some blockbuster G protein–coupled receptor (GPCR) drugs, only a small fraction (∼15%) of the more than 390 nonodorant GPCRs have been successfully targeted by the pharmaceutical industry. One way that this issue might be addressed is via translation of recent deorphanization programs that have opened the prospect of extending the reach of new medicine design to novel receptor types with potential therapeutic value. Prominent among these receptors are those that respond to short-chain free fatty acids of carbon chain length 2–6. These receptors, FFA2 (GPR43) and FFA3 (GPR41), are each predominantly activated by the short-chain fatty acids acetate, propionate, and butyrate, ligands that originate largely as fermentation by-products of anaerobic bacteria in the gut. However, the presence of FFA2 and FFA3 on pancreatic β-cells, FFA3 on neurons, and FFA2 on leukocytes and adipocytes means that the biologic role of these receptors likely extends beyond the widely accepted role of regulating peptide hormone release from enteroendocrine cells in the gut. Here, we review the physiologic roles of FFA2 and FFA3, the recent development and use of receptor-selective pharmacological tool compounds and genetic models available to study these receptors, and present evidence of the potential therapeutic value of targeting this emerging receptor pair

Efecto Talbot no paraxial en una red unidimensional de periodo comparable a la longitud de onda

The Talbot effect is a diffractive phenomenon which was found since its inception in the Gaussian optics, but when the period of the object is comparable with the wavelength is considered entering its non-paraxial regime. There, it has attracted interest for its applications related to the design of objects and their restorative effects posing in damaged gratings on this scale. In this contribution a study of this phenomenon at level non-paraxial (metaxial) is presented by using scalar diffraction theory in plane waves representation for periodic transversal fields. To this end, a one-dimensional amplitude grating of period p is used which is illuminated by a monochromatic plane wave of wavelength λ where p ranges between 1,5 λ and 4,2 λ.El efecto Talbot es un fenómeno difractivo ubicado desde su origen en la óptica Gaussiana, pero cuando la longitud de onda es comparable con el periodo del objeto se considera que este efecto entra en su régimen no paraxial, el cual nuevamente ha despertado el interés por su volumen de aplicación relacionado con el diseño de objetos y sus efectos curativo que presenta en redes averiadas a esta escala En esta contribución presentamos un estudio de este fenómeno a nivel no paraxial (metaxial),usando la teoría escalar de difracción en representación de ondas planas para campos periódicos transversal. Para ello se utiliza como objeto periódico una red de amplitud unidimensional de periodo p, iluminada con una onda plana monocromática de amplitud unitaria y longitud de onda λ, donde p se encuentra entre 1,5 λ y 4,2 λ.Centro de Investigaciones Óptica

Efecto Talbot no paraxial en una red unidimensional de periodo comparable a la longitud de onda

The Talbot effect is a diffractive phenomenon which was found since its inception in the Gaussian optics, but when the period of the object is comparable with the wavelength is considered entering its non-paraxial regime. There, it has attracted interest for its applications related to the design of objects and their restorative effects posing in damaged gratings on this scale. In this contribution a study of this phenomenon at level non-paraxial (metaxial) is presented by using scalar diffraction theory in plane waves representation for periodic transversal fields. To this end, a one-dimensional amplitude grating of period p is used which is illuminated by a monochromatic plane wave of wavelength λ where p ranges between 1,5 λ and 4,2 λ.El efecto Talbot es un fenómeno difractivo ubicado desde su origen en la óptica Gaussiana, pero cuando la longitud de onda es comparable con el periodo del objeto se considera que este efecto entra en su régimen no paraxial, el cual nuevamente ha despertado el interés por su volumen de aplicación relacionado con el diseño de objetos y sus efectos curativo que presenta en redes averiadas a esta escala En esta contribución presentamos un estudio de este fenómeno a nivel no paraxial (metaxial),usando la teoría escalar de difracción en representación de ondas planas para campos periódicos transversal. Para ello se utiliza como objeto periódico una red de amplitud unidimensional de periodo p, iluminada con una onda plana monocromática de amplitud unitaria y longitud de onda λ, donde p se encuentra entre 1,5 λ y 4,2 λ.Centro de Investigaciones Óptica

Transcranial direct current stimulation (tDCS) in unilateral cerebral palsy: A pilot study of motor effect

Transcranial Direct Current Stimulation (tDCS) is an emerging tool to improve upper limb motor functions after stroke acquired in adulthood; however, there is a paucity of reports on its efficacy for upper limb motor rehabilitation in congenital or early-acquired stroke. In this pilot study we have explored, for the first time, the immediate effects, and their short-term persistence, of a single application of anodal tDCS on chronic upper limb motor disorders in children and young individuals with Unilateral Cerebral Palsy (UCP). To this aim, in a crossover sham-controlled study, eight subjects aged 10-28 years with UCP underwent two sessions of active and sham tDCS. Anodal tDCS (1.5 mA, 20 min) was delivered over the primary motor cortex (M1) of the ipsilesional hemisphere. Results showed, only following the active stimulation, an immediate improvement in unimanual gross motor dexterity of hemiplegic, but not of nonhemiplegic, hand in Box and Block test (BBT). Such improvement remained stable for at least 90 minutes. Performance of both hands in Hand Grip Strength test was not modified by anodal tDCS. Improvement in BBT was unrelated to participants’ age or lesion size, as revealed by MRI data analysis. No serious adverse effects occurred after tDCS; some mild and transient side effects (e.g., headache, tingling, and itchiness) were reported in a limited number of cases. This study provides an innovative contribution to scientific literature on the efficacy and safety of anodal tDCS in UCP

Photoproduction of electron-positron pairs in bent single crystals

The process of photoproduction of electron-positron pairs in bent single crystals is considered in this paper. In particular, it is shown that the probability of the process for gamma-quanta with energies from 100 GeV on is significantly higher than the one in an amorphous medium. A possible scenario for the experimental validation of the process is discussed and the positive features of the photoproduction in bent crystals compared to straight ones are underlined from the point of view of possible applications.Comment: 13 pages, 6 figure

No efficacy of transcranial direct current stimulation on chronic migraine with medication overuse : a double blind, randomised clinical trial

Background: Transcranial direct current stimulation was suggested to provide beneficial effects in chronic migraine, a condition often associated with medication overuse for which no long-term therapy is available. Methods: We conducted a randomised controlled trial to assess long-term efficacy of transcranial direct current stimulation. Adults diagnosed with chronic migraine and medication overuse were assigned to receive in a 1:1:1 ratio anodal, cathodal, or sham transcranial direct current stimulation daily for five consecutive days, along with standardised drug withdrawal protocol. Primary outcome was 50% reduction of days of headache per month at 12 months. Co-secondary outcomes were 50% reduction of days of headache per month at 6 months, reduction of analgesic intake per month, and change in disability and quality of life, catastrophising, depression, state and trait anxiety, dependence attitude and allodynia intensity. Patients were not allowed to take any migraine prophylaxis drug for the entire study period. Results: We randomly allocated 135 patients to anodal (44), cathodal (45), and sham (46) transcranial direct current stimulation. At 6 and 12 months, the percentage of reduction of days of headache and number of analgesics per month ranged between 48.5% and 64.7%, without differences between transcranial direct current stimulation (cathodal, anodal, or the results obtained from the two arms of treatment, anodal plus cathodal) and sham. Catastrophising attitude significantly reduced at 12 months in all groups. There was no difference for the other secondary outcomes. Conclusions: Transcranial direct current stimulation did not influence the short and long-term course of chronic migraine with medication overuse after acute drug withdrawal. Behavioral and educational measures and support for patients' pain management could provide long-term improvement and low relapse rate. Trial registration number NCT04228809

Efecto Talbot no paraxial en una red unidimensional de periodo comparable a la longitud de onda

The Talbot effect is a diffractive phenomenon which was found since its inception in the Gaussian optics, but when the period of the object is comparable with the wavelength is considered entering its non-paraxial regime. There, it has attracted interest for its applications related to the design of objects and their restorative effects posing in damaged gratings on this scale. In this contribution a study of this phenomenon at level non-paraxial (metaxial) is presented by using scalar diffraction theory in plane waves representation for periodic transversal fields. To this end, a one-dimensional amplitude grating of period p is used which is illuminated by a monochromatic plane wave of wavelength λ where p ranges between 1,5 λ and 4,2 λ.El efecto Talbot es un fenómeno difractivo ubicado desde su origen en la óptica Gaussiana, pero cuando la longitud de onda es comparable con el periodo del objeto se considera que este efecto entra en su régimen no paraxial, el cual nuevamente ha despertado el interés por su volumen de aplicación relacionado con el diseño de objetos y sus efectos curativo que presenta en redes averiadas a esta escala En esta contribución presentamos un estudio de este fenómeno a nivel no paraxial (metaxial),usando la teoría escalar de difracción en representación de ondas planas para campos periódicos transversal. Para ello se utiliza como objeto periódico una red de amplitud unidimensional de periodo p, iluminada con una onda plana monocromática de amplitud unitaria y longitud de onda λ, donde p se encuentra entre 1,5 λ y 4,2 λ.Centro de Investigaciones Óptica

Seeing touches early in life

Addabbo M, Longhi E, Bolognini N, et al. Seeing touches early in life. PLoS ONE. 2015;10(9): e0134549