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Resume Introduction Les progres de la medecine perinatale ont permis la survie de nouveau-nes de plus en plus immatures. Cependant, l’extreme prematurite est a haut risque d’anomalies du developpement. Nous avons etudie le devenir neurocognitif a 3 ans d’une cohorte d’enfants nes avant 26 semaines d’amenorrhee (SA). Methode Il s’est agi d’une etude observationnelle descriptive d’une cohorte d’enfants nes entre 23 + 0 SA et 25 + 6 SA, dans la region Provence-Alpes-Cote-d’Azur (PACA) Ouest–Corse du Sud, entre 2007 et 2011. Les donnees du suivi du reseau d’aval « Naitre et devenir » ont permis de classer les enfants en trois groupes : absence de deficience, deficience intermediaire et deficience severe. A l’aide d’une regression logistique, nous avons recherche les facteurs perinatals predictifs d’un devenir favorable a 3 ans. Resultats Cent soixante-deux enfants avaient ete admis en neonatologie. Parmi les 101 survivants (62 %), 66 avaient effectue leur visite a 3 ans. Le taux de survie augmentait avec l’âge gestationnel : 33 % a 23 SA, 57 % a 24 SA et 68 % a 25 SA. Les caracteristiques perinatales des perdus de vue etaient comparables a celles des enfants suivis. Aucune deficience n’a ete depistee chez 56 % et une deficience severe etait presente chez 6 %. Une paralysie cerebrale etait presente chez 13 % des enfants. La faible duree de ventilation mecanique (odd ratio [OR] = 0,96 [0,93–0,99] ; p = 0,03) et la presence d’une corticotherapie antenatale complete (OR = 4,7 [1–7,7–17] ; p = 0,02) etaient associees a l’absence de deficience a 3 ans. Conclusion Ameliorer la prise en charge perinatale de ces nouveau-nes reste un enjeu majeur des equipes soignantes. L’evaluation neurocognitive doit se poursuivre jusqu’a la petite enfance afin de depister les troubles des apprentissages.

International audience; The study of radiation biology on laser-based accelerators is most interesting due to the unique irradiation conditions they can produce, in terms of peak current and duration of the irradiation. In this paper we present the implementation of a beam transport system to transport and shape the proton beam generated by laser-target interaction for in vitro irradiation of biological samples. A set of four permanent magnet quadrupoles is used to transport and focus the beam, efficiently shaping the spectrum and providing a large and relatively uniform irradiation surface. Real time, absolutely calibrated, dosimetry is installed on the beam line, to enable shot-to-shot control of dose deposition in the irradiated volume. Preliminary results of cell sample irradiation are presented to validate the robustness of the full system.

Monitoring of blood glucose is usually reported to reduce the risk of hypoglycemia in term newborns with high risk factors and for prematurity in neonatal intensive care unit patients. Differential diagnosis has rarely been discussed. In the eutrophic term newborn, hypoglycemia remains rare and an etiological diagnosis must be made. Intensive management of neonatal hypoglycemia is required to prevent neurodevelopmental defects. Without evident cause or if hypoglycemia persists, a systematic review of possible causes should be made. We report isolated glucocorticoid deficiency diagnosed in an infant at 10 months of age. This boy had neonatal hypoglycemia and mild jaundice that had not been investigated. During his first 9 months of life, he presented frequent infections. At 10 months of age, febrile seizures occurred associated with shock, hypoglycemia, hyponatremia, mild hyperpigmentation, and coma. He was diagnosed with hypocortisolemia and elevated ACTH levels. Brain injury was revealed by MRI after resuscitation, with hypoxic-ischemic and hypoglycemic encephalopathy. The molecular studies demonstrated the presence of p.Asp107Asn and previously unreported frameshift p.Pro281GlnfsX9 MC2R gene mutations. A substitutive hormone therapy was provided and during a follow-up of 12 months no adrenal crisis was noted. We report an unusual case of familial glucocorticoid deficiency with severe neurological injury. This case demonstrates the importance of an appropriate etiological diagnosis in neonatal hypoglycemia.

We have investigated high harmonic generation in an argon gas cell driven by two femtosecond laser pulses separated by a variable delay ranging from 500 fs to 100 ps. Experiments were performed at the LASERIX IR-EUV facility using an amplified 10 Hz CPA Ti:Sapphire laser system on a beamline delivering 50 fs pulses at 800 nm with energy up to 25 mJ. In the case of a non-zero time delay we studied the optimal conditions for equilibrated double pulse generation despite perturbation of the generating medium induced by the first pulse. We showed how high harmonic double pulse generation varies with the gas pressure, the excitation energy, the delay and the relative polarization between the two laser pulses.

X-ray laser simulations based on Ehybrid code have shown that enhanced plasma x-ray laser emission can be achieved mastering the ionization dynamics and plasma temperature using one long and two short pulses (Ursescu and Ionel, J Optoelectron Adv Mat 12:48–51, 2010). In parallel, two simple methods to generate multiple short pulses for pumping x-ray lasers were reported in conjunction with x-ray laser developments. Five to ten fold enhancement in the emission of the silver x-ray laser was demonstrated using the newly developed pump methods, when compared with the traditional one, based on a long pulse followed by one short pump pulse. An overview of these recent experiments will be presented. The possible implementation of these novel x-ray laser pumping methods at Extreme Light Infrastructure—Nuclear Physics facility will be discussed.

Seeded operation of a Neon-like Titanium plasma-based soft x-ray laser is described. The plasma amplifier is pumped using a variation of the classical grazing incidence pumping technique, combining a long low energy pulse followed by a main short pulse. Because the preformed plasma is underionized, a part of the main short pulse energy is used to ionized it to the lasing stage. Consequences of this feature on seeded laser properties are discussed.

We have investigated a new scheme for laser plasma transient collisional soft x-ray lasers based on the use of an additional laser to produce the preplasma. Soft x-ray emission measurements made for different solid targets are presented and discussed. A significant enhancement of the SXRL emission as compared to double-pulse single-beam grazing incidence (DGRIP) using the same pump laser is reported for 13.9- and 32.6-nm SXRL wavelengths.

An alternative, novel multiple pulse generation scheme was implemented directly after the optical compressor output of an x-ray pump laser. The new method uses a polarization sensitive thin film beam splitter and a half-wavelength wave plate for tuning the energy ratio in the multiple short pulses. Based on this method, an extensive study was made of the running parameters for a grazing incidence pumped silver x-ray laser (XRL) pumped with a long pulse of 145 mJ in 6 ns at 532 nm and up to 1.45 J in few picoseconds at 810 nm. Fivefold enhancement in the emission of the silver XRL was demonstrated using the new pump method.

The LASERIX facility has restarted operation in the middle of the year 2010. Since then, important work has been achieved on the XUV sources performance, reliability and stability, which lead to the construction of two beamlines. The first one is based on transient collisional soft X-ray laser. In the second one, the high order harmonic generation process is used to convert infrared laser into coherent XUV radiations. Characteristics and some recent works on both of them will be presented. Besides, a complete setup for pump-probe experiments has been developed and successfully tested. Some examples involving this device and dealing with plasma opacity, radiobiology and nanomagnetism will be presented. We will conclude this paper by a discussion on how application experiments can be turned into valuable diagnostics for XUV sources.

The influence of temporal pump laser profile on the Soft X-ray laser (SXRL) efficiency is investigated in double grazing incidence pumping (DGRIP) transient collisional scheme. We have demonstrated a simple method that allows to produce and control one or several small prepulses and the ASE level of the pump laser beam by modifying the regenerative amplifier parameters. By changing the temporal structure of the pump beam we observed both an increase of the SXRL energy and an improvement of the target lifetime. Measurements made for different configurations are presented and discussed.

We present in this paper a laser-driven coherent EUV beamline resulting from the combination of a versatile high-order laser harmonic generator with a robust plasma-based EUV laser amplifier. Both devices can be used separetely or in synergy. Seeding of the plasma amplifier by a high-order harmonic beam leads to a strong improvement of the EUV laser beam divergence and uniformity. Moreover the system can be turned easily into a IR pump-XUV probe setup for plasma opacity probing. The possibility to generate two separate harmonic sources from the same gas cell offers the opportunity to explore EUV pump-EUV probe experiments.

The potential for coherent extreme ultra-violet (EUV) light in probing laser-produced plasmas is investigated. New results are presented to demonstrate that EUV radiation can be employed to measure heat penetration into solid targets from electrons using the signature of a change of opacity due to heating. We examine, in particular, the effects of hot electron heating of targets. In addition, phase variations after transmission through a laser-irradiated target change the subsequent propagation of the radiation, suggesting a simple diagnostic measuring the far-field footprint of coherent EUV radiation can be a useful measurement of the uniformity of target heating.

The accurate characterization of thermal electron transport and the determination of heating by suprathermal electrons in laser driven solid targets are both issues of great importance to the current experiments being performed at the National Ignition Facility, which aims to achieve thermonuclear fusion ignition using lasers. Ionization, induced by electronic heat conduction, can cause the opacity of a material to drop significantly once bound-free photoionization is no longer energetically possible. We show that this drop in opacity enables measurements of the transmission of extreme ultraviolet (EUV) laser pulses at 13.9 nm to act as a signature of the heating of thin (50 nm) iron layers with a 50-nm thick parylene-N (CH) overlay irradiated by 35-fs pulses at irradiance $3\ifmmode\times\else\texttimes\fi{}{10}^{16}$ Wcm${}^{\ensuremath{-}2}$. Comparing EUV transmission measurements at different times after irradiation to fluid code simulations shows that the target is instantaneously heated by hot electrons (with approximately 10$%$ of the laser energy), followed by thermal conduction with a flux limiter of $\ensuremath{\approx}$0.05.

International audience; Harmonic seeded operation of a neon-like titanium plasma-based soft x-ray laser is described. The plasma amplifier is pumped with a variation of the grazing incidence technique involving a fast and localized ionization step. We discuss its effect on gain dynamics by measuring the amplifying factor as a function of the delay between pump pulse and harmonic seed. Two different regimes are pointed out, following the pumping scheme used. For one of them, a delay in the gain generation compared with the pumping laser pulse is observed. (C) 2015 Optical Society of America

We demonstrate the use of extreme ultra-violet (EUV) laboratory lasers in probing energy transport in laser irradiated solid targets. EUV transmission through targets containing a thin layer of iron (50 nm) encased in plastic (CH) after irradiation by a short pulse (35 fs) laser focussed to irradiances 3 × 1016 Wcm−2 is measured. Heating of the iron layer gives rise to a rapid decrease in EUV opacity and an increase in the transmission of the 13.9 nm laser radiation as the iron ionizes to Fe5+ and above where the ion ionisation energy is greater than the EUV probe photon energy (89 eV). A one dimensional hydrodynamic fluid code HYADES has been used to simulate the temporal variation in EUV transmission (wavelength 13.9 nm) using IMP opacity values for the iron layer and the simulated transmissions are compared to measured transmission values. When a deliberate pre-pulse is used to preform an expanding plastic plasma, it is found that radiation is important in the heating of the iron layer while for pre-pu...

Many methods have been proposed to estimate the postmortem interval, based in particular on the heat loss of the cadaver. These methods have the advantage of being simple to use and giving a rapid result. However, they raise real problems when the cadaver has been immersed, either totally, partially or temporarily.