Comment on "Fluctuation-induced first-order transition p-wave superconductors" by Qi Li, D. Belitz, and J. Toner [Phys. Rev. B79, 054514 (2009)]

In this Comment, we show that the paper by Qi Li, D. Belitz and J. Toner, published in Phys. Rev. B {\bf 79}, 054514 (2009), contains an incomplete mean-field analysis of a simple model of Ginzburg-Landau type. The latter contains a stable non-unitary phase, which has not been found in this study and is missing in the outlined picture of possible stable phases. In this Comment, the mean field analysis has been corrected, the errors have been explained in details and relevant topics have been discussed. Shortcomings in the mean-field-like and renormalization group studies in the mentioned paper have also been revealed.Comment: accepted in Phys. Rev.

Phase transitions to spin-triplet ferromagnetic superconductivity in neutron stars

Effects of the anisotropy of Cooper pairs in spin-triplet ferromagnetic superconductors are investigated on the basis of the Ginzburg-Landau theory. A special attention is paid to the triggering of the superconducting state by the ferromagnetic order. The ground states of these superconductors are outlined and discussed. The idea about a possible coexistence of ferromagnetism and spin-triplet superconductivity in neutron stars is introduced.Comment: 10 pages Latex2e, 2 figs, Proc. of the Leiden Workshop on Realistic Models in Astrophysical Matter (AIP, N.Y., 2004

Effet de l’extrait hydro-éthanolique des feuilles de Trilepisium madagascariense Leeuwenberg D.C. (Moraceae) contre le stress oxydant associé au diabète sucré chez le rat

Trilepisium madagascariense (Moraceae) est une plante utilisée en médecine traditionnelle congolaise pour traiter le diabète dont l’hyperglycémie est un symptôme cardinal. L’hyperglycémie permanente entraine un stress oxydatif qui est à l’origine de l’apparition de plusieurs complications du diabète (hypertension artérielle, cataracte, insuffisance rénale,…). C’est ainsi que, la présente étude a été entreprise pour évaluer l’effet antioxydant de l’extrait hydro-éthanolique de cette plante chez les rats rendus diabétiques par injection de la streptozotocine. L’administration quotidienne de cet extrait à la dose thérapeutique de 400mg/kg et de l’insuline à 5UI/kg aux rats diabétiques pendant trois semaines a provoqué une augmentation significative de l’activité des enzymes anti-oxydantes (superoxyde dismutase ou SOD et catalase) et des taux de glutathion réduit (GSH) et de monoxyde d’azote (NO), comparativement aux rats diabétiques non traités (ou recevant essentiellement de l’eau), chez lesquels, on a observé une baisse de l’activité de ces enzymes, de GSH et de NO. L’augmentation des marqueurs oxydatifs constatée chez les rats diabétiques traités à l’extrait hydro-éthanolique et à l’insuline est un effet compensatoire en réponse au stress oxydatif provoqué par l’hyperglycémie ; alors que leur baisse est le signe d’une atteinte oxydative qui conduit à l’installation des complications du diabète. En conclusion, Trilepisium madagascariense possède un grand potentiel antioxydant qui lui permet de prévenir ou de minimiser l’installation des complications du diabète.Mots-clés: Trilepisium madagascariense, stress oxydant, prévention, complications, diabète.  Trilepisium madagascariense (Moraceae) is a plant used in Congolese traditional medicine to treat diabetes whose hyperglycemia is a cardinal symptom. The permanent oxidative stress leads to hyperglycemia which is responsible for the appearance of several complications of diabetes (hypertension, cataract , renal failure , ...) . Thus, the present study was undertaken to evaluate the hydro- ethanolic extract of the antioxidant effect of this plant in rats made diabetic by injection of streptozotocin. Daily administration of this extract at the therapeutic dose of 400mg/kg and insulin 5UI/kg to diabetic rats for three weeks caused a significant increase in the activity of antioxidant enzymes (superoxide dismutase or SOD and catalase) and reduced glutathione (GSH) and nitrogen monoxide (NO), compared to untreated diabetic rats (receiving or essentially water) , in which was observed a decrease in activity of these enzymes , GSH and NO . Increased oxidative markers found in diabetic rats treated with ethanolic extracts and insulin is a compensatory effect in response to oxidative stress induced by hyperglycaemia ; while their decrease is a sign of oxidative attack that leads to the installation of the complications of diabetes. In conclusion, Trilepisium madagascariense has great potential antioxidant that enables it to prevent or minimize the installation of diabetic complications.Keywords: Trilepisium madagascariense, oxidative stress, prevention, complications , diabete

Cortical lamina-dependent blood volume changes in human brain at 7T

Cortical layer-dependent high (sub-millimeter) resolution functional magnetic resonance imaging (fMRI) in human or animal brain can be used to address questions regarding the functioning of cortical circuits, such as the effect of different afferent and efferent connectivities on activity in specific cortical layers. The sensitivity of gradient echo (GE) blood oxygenation level-dependent (BOLD) responses to large draining veins reduces its local specificity and can render the interpretation of the underlying laminar neural activity impossible. The application of the more spatially specific cerebral blood volume (CBV)-based fMRI in humans has been hindered by the low sensitivity of the noninvasive modalities available. Here, a vascular space occupancy (VASO) variant, adapted for use at high field, is further optimized to capture layer-dependent activity changes in human motor cortex at sub-millimeter resolution. Acquired activation maps and cortical profiles show that the VASO signal peaks in gray matter at 0.8–1.6 mm depth, and deeper compared to the superficial and vein-dominated GE-BOLD responses. Validation of the VASO signal change versus well-established iron-oxide contrast agent based fMRI methods in animals showed the same cortical profiles of CBV change, after normalization for lamina-dependent baseline CBV. In order to evaluate its potential of revealing small lamina-dependent signal differences due to modulations of the input-output characteristics, layer-dependent VASO responses were investigated in the ipsilateral hemisphere during unilateral finger tapping. Positive activation in ipsilateral primary motor cortex and negative activation in ipsilateral primary sensory cortex were observed. This feature is only visible in high-resolution fMRI where opposing sides of a sulcus can be investigated independently because of a lack of partial volume effects. Based on the results presented here, we conclude that VASO offers good reproducibility, high sensitivity and lower sensitivity than GE-BOLD to changes in larger vessels, making it a valuable tool for layer-dependent fMRI studies in humans

An Affordable Upper-Limb Exoskeleton Concept for Rehabilitation Applications

In recent decades, many researchers have focused on the design and development of exoskeletons. Several strategies have been proposed to develop increasingly more efficient and biomimetic mechanisms. However, existing exoskeletons tend to be expensive and only available for a few people. This paper introduces a new gravity-balanced upper-limb exoskeleton suited for rehabilitation applications and designed with the main objective of reducing the cost of the components and materials. Regarding mechanics, the proposed design significantly reduces the motor torque requirements, because a high cost is usually associated with high-torque actuation. Regarding the electronics, we aim to exploit the microprocessor peripherals to obtain parallel and real-time execution of communication and control tasks without relying on expensive RTOSs. Regarding sensing, we avoid the use of expensive force sensors. Advanced control and rehabilitation features are implemented, and an intuitive user interface is developed. To experimentally validate the functionality of the proposed exoskeleton, a rehabilitation exercise in the form of a pick-and-place task is considered. Experimentally, peak torques are reduced by 89% for the shoulder and by 84% for the elbow

Evaluation of the Sedative and Anticonvulsant Properties of Three Cameroonian Plants

Millettia thonningii, Ocinum sanctum and Securitaca longepedunculaca are used in traditional medicine in Cameroon to treat epilepsy, insomnia and headaches. Animal models of epilepsy (maximal electroshock (MES), n-methyl-d-aspartate (NMDA), pentylenetetrazol (PTZ), isonicotinic hydrazide acid (INH), picrotoxine (PIC) and strychnine (STR)-induced convulsions or turning behavior were used to evaluate anticonvulsant activity while diazepam-induced sleep test was used to evaluate sedative activity of the plants. Four doses of extracts were used for each plant (100, 200, 500 and 1000 mg/kg). At a dose of 1000 mg/kg, Millettia thonningii protected 60 and 90% of mice against MES and PTZ-induced convulsions, respectively. At the same dose, Millettia thonningii also protected 80% of mice against NMDA-induced turning behavior. At a dose of 1000 mg/kg, Ocinum sanctum provided complete protection against MES, PIC and STR- induced convulsions and 83.3% of protection in PTZ test. Securitaca longepedunculata completely protected (100%) mice in PIC test at a dose of 200 mg/kg, in MES test at a dose of 500 mg/kg and in PTZ test at a dose of 1000 mg/kg. 66.7% of mice were protected against STRinduced convulsions. All the three plants showed also sedative properties for they increased significantly and in a dose dependent manner the total sleep time induced by diazepam. The total sleep time of the control groups was multiplied by a factor of 3 at least by each extract. The presence of sedative and anticonvulsant activity in the three plants could explain their use in traditional medicine in the treatment of epilepsy and insomnia in Cameroon.Keywords: Epilepsy; Insomnia; Traditional medicine.doi: 10.4314/ajtcam.v8i5S.2

Meissner phases in spin-triplet ferromagnetic superconductors

We present new results for the properties of phases and phase transitions in spin-triplet ferromagnetic superconductors. The superconductivity of the mixed phase of coexistence of ferromagnetism and unconventional superconductivity is triggered by the presence of spontaneous magnetization. The mixed phase is stable but the other superconducting phases that usually exist in unconventional superconductors are either unstable or for particular values of the parameters of the theory some of them are metastable at relatively low temperatures in a quite narrow domain of the phase diagram. Phase transitions from the normal phase to the phase of coexistence is of first order while the phase transition from the ferromagnetic phase to the coexistence phase can be either of first or second order depending on the concrete substance. Cooper pair and crystal anisotropies determine a more precise outline of the phase diagram shape and reduce the degeneration of ground states of the system but they do not change drastically phase stability domains and thermodynamic properties of the respective phases. The results are discussed in view of application to metallic ferromagnets as UGe2, ZrZn2, URhGe.Comment: 21 pages, 7 figures; Phys. Rev. B (2005) in pres

Anatomic & metabolic brain markers of the m.3243A>G mutation: A multi-parametric 7T MRI study

One of the most common mitochondrial DNA (mtDNA) mutations, the A to G transition at base pair 3243, has been linked to changes in the brain, in addition to commonly observed hearing problems, diabetes and myopathy. However, a detailed quantitative description of m.3243A>G patients' brains has not been provided so far. In this study, ultra-high field MRI at 7T and volume- and surface-based data analyses approaches were used to highlight morphology (i.e. atrophy)-, microstructure (i.e. myelin and iron concentration)- and metabolism (i.e. cerebral blood flow)-related differences between patients (N = 22) and healthy controls (N = 15). The use of quantitative MRI at 7T allowed us to detect subtle changes of biophysical processes in the brain with high accuracy and sensitivity, in addition to typically assessed lesions and atrophy. Furthermore, the effect of m.3243A>G mutation load in blood and urine epithelial cells on these MRI measures was assessed within the patient population and revealed that blood levels were most indicative of the brain's state and disease severity, based on MRI as well as on neuropsychological data. Morphometry MRI data showed a wide-spread reduction of cortical, subcortical and cerebellar gray matter volume, in addition to significantly enlarged ventricles. Moreover, surface-based analyses revealed brain area-specific changes in cortical thickness (e.g. of the auditory cortex), and in T1, T2* and cerebral blood flow as a function of mutation load, which can be linked to typically m.3243A>G-related clinical symptoms (e.g. hearing impairment). In addition, several regions linked to attentional control (e.g. middle frontal gyrus), the sensorimotor network (e.g. banks of central sulcus) and the default mode network (e.g. precuneus) were characterized by alterations in cortical thickness, T1, T2* and/or cerebral blood flow, which has not been described in previous MRI studies. Finally, several hypotheses, based either on vascular, metabolic or astroglial implications of the m.3243A>G mutation, are discussed that potentially explain the underlying pathobiology. To conclude, this is the first 7T and also the largest MRI study on this patient population that provides macroscopic brain correlates of the m.3243A>G mutation indicating potential MRI biomarkers of mitochondrial diseases and might guide future (longitudinal) studies to extensively track neuropathological and clinical changes

Functional cerebral blood volume mapping with simultaneous multi-slice acquisition

The aim of this study is to overcome the current limits of brain coverage available with multi-slice echo planar imaging (EPI) for vascular space occupancy (VASO) mapping. By incorporating simultaneous multi-slice (SMS) EPI image acquisition into slice-saturation slab-inversion VASO (SS-SI VASO), many more slices can be acquired for non-invasive functional measurements of blood volume responses. Blood-volume-weighted VASO and gradient echo blood oxygenation level-dependent (GE-BOLD) data were acquired in humans at 7 T with a 32-channel head coil. SMS-VASO was applied in three scenarios: A) high-resolution acquisition of spatially distant brain areas in the visuo-motor network (V1/V5/M1/S1); B) high-resolution acquisition of an imaging slab covering the entire M1/S1 hand regions; and C) low-resolution acquisition with near whole-brain coverage. The results show that the SMS-VASO sequence provided images enabling robust detection of blood volume changes in up to 20 slices with signal readout durations shorter than 150 ms. High-resolution application of SMS-VASO revealed improved specificity of VASO to GM tissue without contamination from large draining veins compared to GE-BOLD in the visual cortex and in the sensory-motor cortex. It is concluded that VASO fMRI with SMS-EPI allows obtaining a reasonable three-dimensional coverage not achievable with standard VASO during the short time period when blood magnetization is approximately nulled. Due to the increased brain coverage and better spatial specificity to GM tissue of VASO compared to GE-BOLD signal, the proposed method may play an important role in high-resolution human fMRI at 7 T