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We report on the chaotic dynamics in a passively Q-switched 2.3-μm thulium laser operating on the 3H4 → 3H5 transition. The experiment exploits a Tm:LiYF4 crystal and various laser cavity configurations, involving an optional cascade laser on the 3F4 → 3H6 transition at 1.9 μm. The saturable absorber employed is Cr2+:ZnSe, which is exclusively saturated by the 2.3 μm laser. An analysis of the Q-switched dynamics shows a pronounced inclination of the laser operation toward the unstable and chaotic behavior. To understand the origins of this chaos, we monitor the population of the metastable 3F4 level via cascade laser operation at 1.9 μm, underlying this variable as an interesting parameter to survey chaotic instabilities.

Abstract Cerium-doped lutetium-yttrium oxyorthosilicate (Ce:LYSO) is a well-known single crystal scintillator used in medical imaging and security scanners. Recent development of high power UV LED, matching its absorption band, questions the possibility to use Ce:LYSO in a new way: as LED-pumped solid-state light source. Since Ce:LYSO is available in large size crystals, we investigate its potential as a luminescent concentrator. This paper reports an extensive study of the performance in close relation to the spectroscopic properties of this crystal. It gives the reasons why the Ce:LYSO crystal tested in this study is less efficient than Ce:YAG for luminescent concentration: limited quantum efficiency and high losses coming from self-absorption and from excited-state absorption are playing key roles. However, we demonstrate that a Ce:LYSO luminescent concentrator is an innovative source for solid-state lighting. Pumped by a peak power of 3400 W in quasi-continuous wave regime (40 µs, 10 Hz), a rectangular (1 × 22 × 105 mm3) Ce:LYSO crystal delivers a broadband spectrum (60 nm FWHM) centered at 430 nm. At full output aperture (20 × 1 mm2), it emits a peak power of 116 W. On a squared output surface (1 × 1 mm2) it emits 16 W corresponding to a brightness of 509 W cm–2 sr–1. This combination of spectrum power and brightness is higher than blue LEDs and opens perspectives for Ce:LYSO in the field of illumination namely for imaging.

For a recent publication, the authors identified a seven-region model of mammal family distribution patterns, in which each unit contributes equally to the system’s overall statistical characteristics of diversity, despite its individual units having measurably different levels of diversity and endemism. This systemization presents a highly efficient descriptive model that can possibly be interpreted as a form of natural classification. An additional analysis of the same mode is described here, in which the seven-region model of the distribution of mammal families’ spatial affinities is shown to closely approach a most-probable-state arrangement, as assessed through combinatorics, raising some important questions about how macroevolutionary patterns might self-organize spatially. One of the possible practical applications of the overall approach is to areal representation; statistical moments of the underlying world patterns can be used to characterize faunal statuses at any individual location by relating the latter to the former. Through this approach, classical concepts such as corridors, tracks, and transition zones might be re-examined in a manner that better lends itself to hypothesis testing. An arbitrarily chosen bounded area, the conterminous United States, is treated in this fashion by way of illustration.

The extraction efficiency and the brightness are critical parameters to increase the performance of luminescent rectangular slabs such as scintillators, luminescent concentrators, or diamonds with NV centers. This work explains how an additional face breaking the rectangular symmetry can improve the extraction efficiency and brightness. The study is based on a fully analytical approach corroborated experimentally with cerium‐doped yttrium aluminum garnet (Ce:YAG) slabs. The model gives an analytical expression of the extraction efficiency and the brightness of the additional face as a function of the slab parameters (dimensions, refractive index, losses). Results highlight that the extraction efficiency by an additional face can be improved even if the area of the additional face is lower than the area of the smallest face of the slab, generally chosen as the output face in a standard configuration. Therefore, the output brightness can be easily improved and controlled by the dimension of the additional face. Balancing the extraction efficiency and the brightness, a 1 × 3 × 22 mm3 Ce:YAG slab with an optimized edge face and with mirrors on the lateral faces exhibits an efficiency 1.9 times better and a brightness 5.6 higher than a Ce:YAG in a standard configuration.

Biological evolution is generally regarded as a stochastic or probabilistic process, per the ideas of Darwin in the nineteenth century. Even if this is true at the meso-scale, it still may, however, be impacted by overarching constraints that we have not yet identified. In this paper, we revisit the subject of mammal faunal regions with a mind to explore a potential kind of macroevolutionary influence. We first identify an optimum seven-region mammal faunal classification system based on spatial and phylogenetic data from a comprehensive 2013 review, and then examine the possibility that this classification provides supporting evidence for a Spinoza-influenced philosophical/theoretical model of the “natural system” concept developed by one of the authors in the 1980s. The hierarchical pattern of regional affinities revealed does do this.

Laser amplifiers seek high power, efficiency, and short pulse durations. Research laboratories in this field have focused their investigations toward new laser materials that can be efficiently diode pumped, sustain high-power pumping, and have broad emission bandwidth to achieve ultrashort pulse amplification. This is why, for more than ten years now, new Yb-doped materials have been intensively investigated. In the actual state of the art, they represent the more promising and successful materials for these kinds of applications. In this paper, we will do a short review of the last and more impacting discoveries and demonstrations in this field over the last few years.

This trial was conducted to evaluate the safety and immunogenicity of two virosome formulated malaria peptidomimetics derived from Plasmodium falciparum AMA-1 and CSP in malaria semi-immune adults and children.The design was a prospective randomized, double-blind, controlled, age-deescalating study with two immunizations. 10 adults and 40 children (aged 5-9 years) living in a malaria endemic area were immunized with PEV3B or virosomal influenza vaccine Inflexal®V on day 0 and 90.No serious or severe adverse events (AEs) related to the vaccines were observed. The only local solicited AE reported was pain at injection site, which affected more children in the Inflexal®V group compared to the PEV3B group (p = 0.014). In the PEV3B group, IgG ELISA endpoint titers specific for the AMA-1 and CSP peptide antigens were significantly higher for most time points compared to the Inflexal®V control group. Across all time points after first immunization the average ratio of endpoint titers to baseline values in PEV3B subjects ranged from 4 to 15 in adults and from 4 to 66 in children. As an exploratory outcome, we found that the incidence rate of clinical malaria episodes in children vaccinees was half the rate of the control children between study days 30 and 365 (0.0035 episodes per day at risk for PEV3B vs. 0.0069 for Inflexal®V; RR = 0.50 [95%-CI: 0.29-0.88], p = 0.02).These findings provide a strong basis for the further development of multivalent virosomal malaria peptide vaccines.ClinicalTrials.gov NCT00513669.

Background: This trial was conducted to evaluate the safety and immunogenicity of two virosome formulated malaria peptidomimetics derived from Plasmodium falciparum AMA-1 and CSP in malaria semi-immune adults and children. Methods: The design was a prospective randomized, double-blind, controlled, age-deescalating study with two immunizations. 10 adults and 40 children (aged 5-9 years) living in a malaria endemic area were immunized with PEV3B or virosomal influenza vaccine Inflexal®V on day 0 and 90. Results: No serious or severe adverse events (AEs) related to the vaccines were observed. The only local solicited AE reported was pain at injection site, which affected more children in the Inflexal®V group compared to the PEV3B group (p = 0.014). In the PEV3B group, IgG ELISA endpoint titers specific for the AMA-1 and CSP peptide antigens were significantly higher for most time points compared to the Inflexal®V control group. Across all time points after first immunization the average ratio of endpoint titers to baseline values in PEV3B subjects ranged from 4 to 15 in adults and from 4 to 66 in children. As an exploratory outcome, we found that the incidence rate of clinical malaria episodes in children vaccinees was half the rate of the control children between study days 30 and 365 (0.0035 episodes per day at risk for PEV3B vs. 0.0069 for Inflexal®V; RR = 0.50 [95%-CI: 0.29-0.88], p = 0.02). Conclusion: These findings provide a strong basis for the further development of multivalent virosomal malaria peptide vaccines. [ABSTRACT FROM AUTHOR]

We review recent progress in coherent combining of femtosecond pulses amplified in optical fibers as a way to scale the peak and average power of ultrafast sources. Different methods of achieving coherent pulse addition in space (beam combining) and time (divided pulse amplification) domains are described. These architectures can be widely classified into active methods, where the relative phases between pulses are subject to a servomechanism, and passive methods, where phase matching is inherent to the geometry. Other experiments that combine pulses with different spectral contents, pulses that have been nonlinearly broadened or successive pulses from a mode-locked laser oscillator, are then presented. All these techniques allow access to unprecedented parameter range for fiber ultrafast sources. [ABSTRACT FROM AUTHOR]