Biotinidase deficiency in a newborn.

INTRODUCTION: Biotinidase deficiency is an inherited disorder of biotin metabolism that is untreated may present within the first few month of life. OBJECTIVE: We report the exceptional observation of a biotinidase deficiency in Morocco. The rarity of this pathology, its age of onset, its mode of revelation and the lack of treatment in Morocco make the particularity of this observation. OBSERVATION: A newborn child born from a 24-year-old mother, followed by an estimated pregnancy of 37 weeks of amenorrhea according to the Farr score (morphological maturation score used for the dating of the pregnancy term). The infant presented at 7 days of life with a cutaneous-mucous eruption with icithiosic dry erythroderma of interest to the trunk, the face, the scalp associated with alopecia and depilation of the eyebrow. The biotinoidase deficiency was confirmed by its low serum concentration at 49 nka / l. The newborn died at 20 days of life before starting the specific treatment. CONCLUSION: Biotinidase deficiency is a rare condition requiring early screening and rapid management. The delay in diagnosis and the unavailability of treatment in Morocco can have fatal consequences.

Nanoscale sub-100 picosecond all-optical magnetization switching in GdFeCo microstructures.

Ultrafast magnetization reversal driven by femtosecond laser pulses has been shown to be a promising way to write information. Seeking to improve the recording density has raised intriguing fundamental questions about the feasibility of combining ultrafast temporal resolution with sub-wavelength spatial resolution for magnetic recording. Here we report on the experimental demonstration of nanoscale sub-100 ps all-optical magnetization switching, providing a path to sub-wavelength magnetic recording. Using computational methods, we reveal the feasibility of nanoscale magnetic switching even for an unfocused laser pulse. This effect is achieved by structuring the sample such that the laser pulse, via both refraction and interference, focuses onto a localized region of the structure, the position of which can be controlled by the structural design. Time-resolved photo-emission electron microscopy studies reveal that nanoscale magnetic switching employing such focusing can be pushed to the sub-100 ps regime.

Domain wall transformations and hopping in La(0.7)Sr(0.3)MnO(3) nanostructures imaged with high resolution x-ray magnetic microscopy.

We investigate the effect of electric current pulse injection on domain walls in La(0.7)Sr(0.3)MnO(3) (LSMO) half-ring nanostructures by high resolution x-ray magnetic microscopy at room temperature. Due to the easily accessible Curie temperature of LSMO, we can employ reasonable current densities to induce the Joule heating necessary to observe effects such as hopping of the domain walls between different pinning sites and nucleation/annihilation events. Such effects are the dominant features close to the Curie temperature, while spin torque is found to play a small role close to room temperature. We are also able to observe thermally activated domain wall transformations and we find that, for the analyzed geometries, the vortex domain wall configuration is energetically favored, in agreement with micromagnetic simulations.

The effect of magnetic anisotropy on the spin configurations of patterned La(0.7)Sr(0.3)MnO3 elements.

We study the effect of magnetocrystalline anisotropy on the magnetic configurations of La0.7Sr0.3MnO3 bar and triangle elements using photoemission electron microscopy imaging. The dominant remanent state is a low energy flux-closure state for both thin (15 nm) and thick (50 nm) elements. The magnetocrystalline anisotropy, which competes with the dipolar energy, causes a strong modification of the spin configuration in the thin elements, depending on the shape, size and orientation of the structures. We investigate the magnetic switching processes and observe in triangular shaped elements a displacement of the vortex core along the easy axis for an external magnetic field applied close to the hard axis, which is well reproduced by micromagnetic simulations.

Ultrafast heating as a sufficient stimulus for magnetization reversal in a ferrimagnet.

The question of how, and how fast, magnetization can be reversed is a topic of great practical interest for the manipulation and storage of magnetic information. It is generally accepted that magnetization reversal should be driven by a stimulus represented by time-non-invariant vectors such as a magnetic field, spin-polarized electric current, or cross-product of two oscillating electric fields. However, until now it has been generally assumed that heating alone, not represented as a vector at all, cannot result in a deterministic reversal of magnetization, although it may assist this process. Here we show numerically and demonstrate experimentally a novel mechanism of deterministic magnetization reversal in a ferrimagnet driven by an ultrafast heating of the medium resulting from the absorption of a sub-picosecond laser pulse without the presence of a magnetic field.

Artificial kagome arrays of nanomagnets: a frozen dipolar spin ice.

Magnetic frustration effects in artificial kagome arrays of nanomagnets are investigated using x-ray photoemission electron microscopy and Monte Carlo simulations. Spin configurations of demagnetized networks reveal unambiguous signatures of long range, dipolar interaction between the nanomagnets. As soon as the system enters the spin ice manifold, the kagome dipolar spin ice model captures the observed physics, while the short range kagome spin ice model fails.