Light Scattering by Cholesteric Skyrmions

We study the light scattering by localized quasi planar excitations of a Cholesteric Liquid Crystal known as spherulites. Due to the anisotropic optical properties of the medium and the peculiar shape of the excitations, we quantitatively evaluate the cross section of the axis-rotation of polarized light. Because of the complexity of the system under consideration, first we give a simplified, but analytical, description of the spherulite and we compare the Born approximation results in this setting with those obtained by resorting to a numerical exact solution. The effects of changing values of the driving external static electric (or magnetic) field is considered. Possible applications of the phenomenon are envisaged.Comment: 18 pages, 14 figure

Analgesic and Antidepressant Effects of the Clinical Glutamate Modulators Acetyl-L-Carnitine and Ketamine

Pain and depression are leading causes of disability and of profound social and economic burden. Their impact is aggravated by their chronicity and comorbidity and the insufficient efficacy of current treatments. Morphological and functional metabolism studies link chronic pain and depressive disorders to dysfunctional neuroplastic changes in fronto-limbic brain regions that control emotional responses to painful injuries and stressful events. Glutamate modulators are emerging new therapies targeting dysfunctional brain areas implicated in the generation and maintenance of chronic pain and depression. Here, we report the effects of two clinically approved glutamate modulators: acetyl-L-carnitine (ALCAR) and S, R(±)ketamine (KET). ALCAR is a natural neurotrophic compound currently marketed for the treatment of neuropathies. KET is the prototypical non-competitive antagonist at N-methyl-D-aspartate glutamate receptors and a clinically approved anesthetic. Although they differ in pharmacological profiles, ALCAR and KET both modulate aminergic and glutamatergic neurotransmissions and pain and mood. We assessed in rats the effects of ALCAR and KET on cerebral metabolic rates for glucose (rCMRglc) and assessed clinically the effects of ALCAR in chronic pain and of KET in post-operative pain. ALCAR and KET increased rCMRglc at similar degrees in prefrontal, somatosensory, and cingulate cortices, and KET increased rCMRglc at a different, much larger, degree in limbic and dopaminergic areas. While rCMRglc increases in prefrontal cortical areas have been associated with analgesic and antidepressant effects of ALCAR and KET, the marked metabolic increases KET induces in limbic and dopaminergic areas have been related to its psychotomimetic and abuse properties. In patients with chronic neuropathic pain, ALCAR (1,000 mg/day) yielded to a fast (2 weeks) improvement of mood and then of pain and quality of life. In day-surgery patients, KET improved dischargeability and satisfaction. In obese patients undergoing bariatric surgery, a single, low dose of KET (0.5 mg/kg) at induction of anesthesia determined a very fast (hours) amelioration of post-operative depression and pain and an opioid-sparing effect. These findings indicate that ALCAR and KET, two non-selective glutamate modulators, still offer viable therapeutic options in comorbid pain and depression

Confinement of chiral molecules in reverse micelles:FT-IR,polarimetric and VCD investigation on the state of dimethyl tartrate in sodium bis(2-ethylhexyl) sulfosuccinate reverse micelles dispersed in carbon tetrachloride

The state of d and l-dimethyl tartrate confined within dry sodium bis(2-ethylhexyl) sulfosuccinate (AOT) reverse micelles dispersed in CCl4 has been investigated by FT-IR spectroscopy, polarimetry, and vibrational circular dichroism (VCD). Measurements have been performed at 25 ◦C as a function of the solubilizate-to-surfactant molar ratio (R) at a fixed AOT concentration (0.158 M). The analysis of experimental data is consistent with the hypothesis that both enantiomers of dimethyl tartrate are mainly entrapped in the reverse micelles and located in proximity to the surfactant head-group region. The formation of this interesting self-organized chiral nanostructure involves some changes of the typical H-bonding of dimethyl tartrates in the pure solid state or as monomers dispersed in CCl4 attributable to the establishment of specific solubilizate/surfactant head-group interactions and confinement effects

Grasp planning with a soft reconfigurable gripper exploiting embedded and environmental constraints

Grasping in unstructured environments requires highly adaptable and versatile hands together with strategies to exploit their features to get robust grasps. This paper presents a method to grasp objects using a novel reconfigurable soft gripper with embodied constraints, the Soft ScoopGripper (SSG). The considered grasp strategy, called scoop grasp, exploits the SSG features to perform robust grasps. The embodied constraint, i.e., a scoop, is used to slide between the object and a flat surface (e.g., a table or a wall) in contact with it. The fingers are first configured according to object geometry and then used to establish reliable contact with it. Given the object to be grasped, the proposed grasp planner chooses the best configuration of the fingers and the scoop based on the object point cloud and then suitably aligns the gripper to it

IUCN red list evaluation of the orchidaceae endemic to apulia (Italy) and considerations on the application of the IUCN protocol to rare species

The conservation status of the ten taxonomically currently recognised orchid species and subspecies (eight in the genus Ophrys, and one each in the genera Epipactis and Serapias) endemic to Apulia (southeast Italy) is presented. Each taxon has been assessed against the internationally accepted IUCN criteria and categories. Of the ten taxa, eight ones are classified as threatened (Endangered or Vulnerable), one as Near Threatened and one as Least Concern. Given that nine of the ten analysed taxa were recently assessed, a comparison with the previous assessments is presented: 67% of the assessed taxa changed their IUCN category. Four taxa (Ophrys murgiana, O. oxyrrhynchos subsp. ingrassiae, O. peucetiae, O. tardans) are now assigned to a higher threat category, while two taxa (Ophrys gravinensis and O. oestrifera subsp. montis-gargani) are now assigned to a lower threat category. These category changes in such a very short time are due to the better knowledge on the number of mature individuals and on the threats affecting the species, and to the discovery of new occurring sites. The most important category change affects Ophrys tardans. The new assessment leads to the category Endangered, whereas in the previous assessment this species was indicated as Least Concern, i.e. as not threatened. Another species with a noteworthy category increase is Ophrys peucetiae, previously indicated as Least Concern and now assigned to the category Vulnerable. The authors discuss these results, highlighting that especially when assessing rare species with a small distribution range against the IUCN protocol, it should be taken into account that the assessment could be influenced (also noteworthy) by the effective knowledge on the distribution, on the population size and on the threats affecting the populations. As a consequence, field work is warmly suggested before assessing the threat category of rare taxa, given that an increased effort in field research often leads to the discovery of new sites and to a better estimation of the number of individuals and of the threats

Effects of physical stresses on radish seed germination and growth

In this work we explore the consequences on variable magnetic fields applied to radish seeds (Raphanus sativum L.) on germination and seedling growth. Three, different alternate magnetic fields have been tested having a high intensity, 40 mT, at very low frequency, 0.2 Hz (B0.2), a low intensity, 577 µT, at low frequency, 370 kHz (B370), and a very low intensity, about 250 nT, at ultra high frequency, 900 MHz (RF900). These last generate electromagnetic waves which are nowadays very used for mobile communications. Groups of uniform radish seeds were exposed to alternate magnetic fields at three duration time values: i) 120 h (BO.2/1), 260 h (B0.2/2) and 360 h (B0.2/3) at high intensity and very low frequency, 0.2 Hz; ii) 120 h (B370/1), 260 h (B370/2), 360 h (B370/3) at low intensity and low frequency, 370 kHz; iii) 120 h (RF/1), 260 h (RF/2), 360 h (RF/3) at very low intensity and ultra high frequency, 900 MHz. Furthermore, another group of seeds was treated by laser beams of 248 nm wavelength whose magnetic field is coupled to an electric field. These two fields, by the Planck theory, origin the quantum energy, expresses by photons. Therefore, in the laser-matter interaction photons are absorbed dependent on laser shots. Again, we performed experiments at three duration time values that applied: 30 kshots (KrF/1), 80 kshots (KrF/2) and 135 kshots (KrF/3) at 40 mJcm2/ fluence. The magnetic field and electric field presented by the laser beam are approximatively 250 kVm/ and 850 µT, respectively. All treatments were performed at room temperature. Both untreated seeds and each group of seeds exposed to the physical stresses were transferred in Petri dishes and followed for their germination and seedling growth up to 96 h. The results showed that all physical stresses induced by alternate magnetic fields, radiofrequency and laser radiations did not have effect on seed germination as well as on cell elongation growth of the radish hypocotyls in comparison to control seeds. On the contrary, all physical stresses showed a significate stimulation on root growth