Femtosecond Mamyshev oscillator at 920 nm.

A femtosecond all-PM-fiber Mamyshev oscillator (MO) at 920 nm is presented. It is based on a neodymium-doped fiber with a W-type index profile that effectively suppresses the emission around 1064 nm. The linear cavity is bounded by two near-zero dispersion fiber Bragg gratings with Gaussian reflectivity profiles. The laser is self-starting and generates up to 10-nJ pulses at a repetition rate of 41 MHz. The pulses can be compressed to 53 fs with a grating-pair compressor. To our knowledge, this is the first Mamyshev oscillator and also the highest energy femtosecond fiber oscillator demonstrated in this spectral region.

Multi-megawatt pulses at 50 MHz from a single-pump Mamyshev oscillator gain-managed amplifier laser.

We have developed a compact all-PM-fiber ytterbium-doped Mamyshev oscillator-amplifier laser system generating compressed pulses of 102 nJ and 37 fs, thus having over 2 MW of peak power, at a repetition rate of 52 MHz. The pump power from a single diode is shared between a linear cavity oscillator and a gain-managed nonlinear amplifier. The oscillator is self-started by pump-modulation and a linearly polarized single-pulse operation is achieved without filter tuning. The cavity filters are near-zero dispersion fiber Bragg gratings with a Gaussian spectral response. To our knowledge, this simple and efficient source has the highest repetition rate and average power among all-fiber multi-megawatt femtosecond pulsed laser sources and its architecture holds potential for generating higher pulse energies.

Oak masting drivers vary between populations depending on their climatic environments.

Large interannual variation in seed production, called masting, is very common in wind-pollinated tree populations and has profound implications for the dynamics of forest ecosystems and the epidemiology of certain human diseases.1,2,3,4,5 Comparing the reproductive characteristics of populations established in climatically contrasting environments would provide powerful insight into masting mechanisms, but the required data are extremely scarce. We built a database from an unprecedented fine-scale 8-year survey of 150 sessile oak trees (Quercus petraea) from 15 populations distributed over a broad climatic gradient, including individual recordings of annual flowering effort, fruiting rate, and fruit production. Although oak masting was previously considered to depend mainly on fruiting rate variations,6,7 we show that the female flowering effort is highly variable from year to year and explains most of the fruiting dynamics in two-thirds of the populations. What drives masting was found to differ among populations living under various climates. In soft-climate populations, the fruiting rate increases initially strongly with the flowering effort, and the intensity of masting results mainly from the flowering synchrony level between individuals. By contrast, the fruiting rate of harsh-climate populations depends mainly on spring weather, which ensures intense masting regardless of the flowering synchronization level. Our work highlights the need for jointly measuring flowering effort and fruit production to decipher the diversity of masting mechanisms among populations. Accounting for such diversity will be decisive in proposing accurate, and possibly contrasted, scenarios about future reproductive patterns of perennial plants with ongoing climate change and their numerous cascading effects.

Effects of stand structure and ungulates on understory vegetation in managed and unmanaged forests.

Conventional conservation policies in Europe notably rely on the passive restoration of natural forest dynamics by setting aside forest areas to preserve forest biodiversity. However, since forest reserves cover only a small proportion of the territory, conservation policies also require complementary conservation efforts in managed forests in order to achieve the biodiversity targets set up in the Convention on Biological Diversity. Conservation measures also raise the question of large herbivore management in and around set-asides, particularly regarding their impact on understory vegetation. Although many studies have separately analyzed the effects of forest management, management abandonment, and ungulate pressure on forest biodiversity, their joint effects have rarely been studied in a correlative framework. We studied 212 plots located in 15 strict forest reserves paired with adjacent managed forests in European France. We applied structural equation models to test the effects of management abandonment, stand structure, and ungulate pressure on the abundance, species richness, and diversity of herbaceous vascular plants and terricolous bryophytes. We showed that stand structure indices and plot-level browsing pressure had direct and opposite effects on herbaceous vascular plant species diversity; these effects were linked with the light tolerance of the different species groups. Increasing canopy cover had an overall negative effect on herbaceous vascular plant abundance and species diversity. The effect was two to three times greater in magnitude than the positive effects of browsing pressure on herbaceous plants diversity. On the other hand, a high stand density index had a positive effect on the species richness and diversity of bryophytes, while browsing had no effect. Forest management abandonment had few direct effects on understory plant communities, and mainly indirectly affected herbaceous vascular plant and bryophyte abundance and species richness and diversity through changes in vertical stand structure. Our results show that conservation biologists should rely on foresters and hunters to lead the preservation of understory vegetation communities in managed forests since, respectively, they manipulate stand structure and regulate ungulate pressure. Their management actions should be adapted to the taxa at stake, since bryophytes and vascular plants respond differently to stand and ungulate factors.

All-fiber Mamyshev oscillator enabled by chirped fiber Bragg gratings.

We present a linear cavity self-polarizing Mamyshev oscillator at 1550 nm made fully of polarization-maintaining fibers. The cavity filters are chirped fiber Bragg gratings with a Gaussian reflectivity profile that allow for greater reflectivity, larger bandwidth, and dispersion control. This mode-locked fiber laser architecture shows an unprecedented simplicity while delivering 21.3-nJ pulses compressed to 108 fs with a competitive 22.3% pump conversion efficiency. Mode locking is initiated with an external saturable absorber mirror. Numerical simulations show how nonlinearity can be managed with highly dispersive filters inside a Mamyshev oscillator.

Erbium-doped aluminophosphosilicate all-fiber laser operating at 1584 nm.

We report on an ytterbium-free erbium-doped aluminophosphosilicate all-fiber laser, producing an output power of 25 W at a wavelength of 1584 nm with a slope efficiency of 30% with respect to the 976 nm absorbed pump power. The simple cavity design proposed takes advantage of fiber Bragg gratings written directly in the gain fiber. The single-mode erbium-doped aluminophosphosilicate fiber was fabricated in-house and was doped with 0.06 mol.% of Er2O3, 1.77 mol.% of Al2O3 and 1.04 mol.% of P2O5. The incorporation of aluminium and phosphorus into the fiber core allowed for an increased concentration of erbium without inducing significant clustering, while keeping the numerical aperture low to ensure a single-mode laser operation.

Flower phenology as a disruptor of the fruiting dynamics in temperate oak species.

Many perennial plants display masting, that is, fruiting with strong interannual variations, irregular and synchronized between trees within the population. Here, we tested the hypothesis that the early flower phenology in temperate oak species promotes stochasticity into their fruiting dynamics, which could play a major role in tree reproductive success. From a large field monitoring network, we compared the pollen phenology between temperate and Mediterranean oak species. Then, focusing on temperate oak species, we explored the influence of the weather around the time of budburst and flowering on seed production, and simulated with a mechanistic model the consequences that an evolutionary shifting of flower phenology would have on fruiting dynamics. Temperate oak species release pollen earlier in the season than do Mediterranean oak species. Such early flowering in temperate oak species results in pollen often being released during unfavorable weather conditions and frequently results in reproductive failure. If pollen release were delayed as a result of natural selection, fruiting dynamics would exhibit much reduced stochastic variation. We propose that early flower phenology might be adaptive by making mast-seeding years rare and unpredictable, which would greatly help in controlling the dynamics of seed consumers.

Femtosecond fiber Mamyshev oscillator at 1550 nm.

We investigated the possibility of reaching nanojoule-level pulse energies in a femtosecond erbium-doped fiber Mamyshev oscillator. In experiments, lasers generate stable pulse trains with energy up to 31.3 nJ, which is comparable to the highest achieved by prior ultrafast erbium fiber lasers. The pulse duration after a grating compressor is around 100 fs. However, as the pulse energy increases, the pulse quality degrades significantly, with a substantial fraction of the energy going into a picosecond pedestal. Numerical simulations agree with the experimental observations, and allow us to identify the gain spectrum and the nonlinearity of the erbium-doped fibers as challenges to the operation of such oscillators at high pulse energy.

Pollen limitation as a main driver of fruiting dynamics in oak populations.

In many perennial wind-pollinated plants, the dynamics of seed production is commonly known to be highly fluctuating from year to year and synchronised among individuals within populations. The proximate causes of such seeding dynamics, called masting, are still poorly understood in oak species that are widespread in the northern hemisphere, and whose fruiting dynamics dramatically impacts forest regeneration and biodiversity. Combining long-term surveys of oak airborne pollen amount and acorn production over large-scale field networks in temperate areas, and a mechanistic modelling approach, we found that the pollen dynamics is the key driver of oak masting. Mechanisms at play involved both internal resource allocation to pollen production synchronised among trees and spring weather conditions affecting the amount of airborne pollen available for reproduction. The sensitivity of airborne pollen to weather conditions might make oak masting and its ecological consequences highly sensitive to climate change.

The role of ungulates in nowadays temperate forests. A response to Fløjgaard et al. (DOI:10.1111/gcb.14029).

In Boulanger et al. (2018), we investigated the effects of ungulates on forest plant diversity. By suggesting a revisit of our conclusions regarding ecosystem dynamics since the late Pleistocene, Fløjgaard et al. (2018) came to the conclusion that moderate grazing in forest should be a conservation target. Since major points of our paper were mis- or over- interpreted, we put the record straight on our study system and on the scope of our conclusions. Finally, we advocate for an assessment of the conservation issues of ungulates in forests not only regarding hypothetical and still debated states of past ecosystems but also considering timely challenges for forest ecosystems.

Ungulates increase forest plant species richness to the benefit of non-forest specialists.

Large wild ungulates are a major biotic factor shaping plant communities. They influence species abundance and occurrence directly by herbivory and plant dispersal, or indirectly by modifying plant-plant interactions and through soil disturbance. In forest ecosystems, researchers' attention has been mainly focused on deer overabundance. Far less is known about the effects on understory plant dynamics and diversity of wild ungulates where their abundance is maintained at lower levels to mitigate impacts on tree regeneration. We used vegetation data collected over 10 years on 82 pairs of exclosure (excluding ungulates) and control plots located in a nation-wide forest monitoring network (Renecofor). We report the effects of ungulate exclusion on (i) plant species richness and ecological characteristics, (ii) and cover percentage of herbaceous and shrub layers. We also analyzed the response of these variables along gradients of ungulate abundance, based on hunting statistics, for wild boar (Sus scrofa), red deer (Cervus elaphus) and roe deer (Capreolus capreolus). Outside the exclosures, forest ungulates maintained higher species richness in the herbaceous layer (+15%), while the shrub layer was 17% less rich, and the plant communities became more light-demanding. Inside the exclosures, shrub cover increased, often to the benefit of bramble (Rubus fruticosus agg.). Ungulates tend to favour ruderal, hemerobic, epizoochorous and non-forest species. Among plots, the magnitude of vegetation changes was proportional to deer abundance. We conclude that ungulates, through the control of the shrub layer, indirectly increase herbaceous plant species richness by increasing light reaching the ground. However, this increase is detrimental to the peculiarity of forest plant communities and contributes to a landscape-level biotic homogenization. Even at population density levels considered to be harmless for overall plant species richness, ungulates remain a conservation issue for plant community composition.

Network connectivity value.

In order to unveil the value of network connectivity, we formalize the construction of ecological networks in forest environments as an optimal control dynamic graph-theoretic problem. The network is based on a set of bioreserves and patches linked by ecological corridors. The node dynamics, built upon the consensus protocol, form a time evolutive Mahalanobis distance weighted by the opportunity costs of timber production. We consider a case of complete graph, where the ecological network is fully connected, and a case of incomplete graph, where the ecological network is partially connected. The results show that the network equilibrium depends on the size of the reception zone, while the network connectivity depends on the environmental compatibility between the ecological areas. Through shadow prices, we find that securing connectivity in partially connected networks is more expensive than in fully connected networks, but should be undertaken when the opportunity costs are significant.

Fruiting Strategies of Perennial Plants: A Resource Budget Model to Couple Mast Seeding to Pollination Efficiency and Resource Allocation Strategies.

Masting, a breeding strategy common in perennial plants, is defined by seed production that is highly variable over years and synchronized at the population level. Resource budget models (RBMs) proposed that masting relies on two processes: (i) the depletion of plant reserves following high fruiting levels, which leads to marked temporal fluctuations in fruiting; and (ii) outcross pollination that synchronizes seed crops among neighboring trees. We revisited the RBM approach to examine the extent to which masting could be impacted by the degree of pollination efficiency, by taking into account various logistic relationships between pollination success and pollen availability. To link masting to other reproductive traits, we split the reserve depletion coefficient into three biological parameters related to resource allocation strategies for flowering and fruiting. While outcross pollination is considered to be the key mechanism that synchronizes fruiting in RBMs, our model counterintuitively showed that intense masting should arise under low-efficiency pollination. When pollination is very efficient, medium-level masting may occur, provided that the costs of female flowering (relative to pollen production) and of fruiting (maximum fruit set and fruit size) are both very high. Our work highlights the powerful framework of RBMs, which include explicit biological parameters, to link fruiting dynamics to various reproductive traits and to provide new insights into the reproductive strategies of perennial plants.

BiOsimilaRs in the management of anaemia secondary to chemotherapy in HaEmatology and Oncology: results of the ORHEO observational study.

BACKGROUND: The approval of epoetin biosimilars in the European Union requires extensive scientific evaluation and stringent regulatory procedures, including post-marketing studies. The ORHEO (place of biOsimilaRs in the therapeutic management of anaemia secondary to chemotherapy in HaEmatology and Oncology) study was an observational, longitudinal, multicentre study performed in France to evaluate the efficacy and safety of biosimilar epoetins for the treatment of chemotherapy-induced anaemia (CIA) in the clinical setting. METHODS: Patients >18 years with CIA (haemoglobin [Hb] <11 g/dL) in association with solid tumours, lymphoma or myeloma and eligible for treatment with an epoetin biosimilar were included in this study. Patient characteristics were recorded at baseline along with anaemia-related information, such as observed and target Hb (as chosen by the treating clinician), brand and dose of epoetin biosimilar prescribed, and details of any other treatments. Patients were then followed-up at 3 and 6 months. The primary endpoint was Hb response (defined as Hb reaching ≥10 g/dL, an increase of Hb ≥1 g/dL since inclusion visit or reaching physician-defined target Hb, with no blood transfusions in the 3 weeks prior to measurement). Other endpoints included adverse events, achievement of target Hb and associated treatments. RESULTS: Overall, 2333 patients >18 years (mean age 66.5 years) with CIA (haemoglobin [Hb] <11 g/dL) in association with solid tumours, lymphoma or myeloma and eligible for biosimilar epoetin treatment were included. 99.9% of patients received epoetin zeta (median dose 30,000 IU/week). Mean baseline Hb was 9.61 g/dL, with 35.6% of patients having moderate anaemia (Hb 8-9.5 g/dL). Hb response was achieved in 81.6% and 86.5% of patients at 3 and 6 months, respectively. Overall mean change in Hb level was 1.52 ± 1.61 and 1.72 ± 1.61 g/dL at 3 and 6 months, respectively. Transfusion and thromboembolic event rates were 9.4% and 2.4% at 3 months, and 5.8% and 1.5% at 6 months, respectively. CONCLUSIONS: Epoetin zeta was effective and well tolerated in the management of CIA in patients with solid tumours, lymphoma and myeloma. TRIAL REGISTRATION NUMBER: NCT02140736 (date of registration: 14 May 2014).

Granocyte-colony stimulating factor (G-CSF) has significant efficacy as secondary prophylaxis of chemotherapy-induced neutropenia in patients with solid tumors: results of a prospective study.

AIM: To carry out a prospective, multicenter and observational study describing prophylactic strategies [cycle delay, dose-reduction, (G-CSF) prescription] to prevent recurrence of neutropenic events (NE) in patients with solid tumors, and identify potential predictive factors of NE recurrence. PATIENTS AND METHODS: Patients ≥18 years old with an NE in a previous chemotherapy cycle (cycle A) without G-CSF support, followed for four cycles (B to E) were included in the study. NE was defined as any neutropenia grade 1-4, febrile or not, which impacted on subsequent chemotherapy cycles (cycle delay, or reduction, or prophylactic G-CSF). RESULTS: Data of 548 patients were analyzed, 378 (69%) were female, with a mean (SD) age of 61.7 (12.3) years. WHO PS: 0-1: 88.3%, incidence of breast cancer: 40%, metastatic disease: 53.3%. Following the first NE episode, 44.5% of patients had cycle delay, 22.3% dose reduction and 466 (85%) received prophylactic G-CSF. NE recurrence rates were: 21.2% at cycle B, 18.6% at cycle C, 11.5% at cycle D and 12.9% at cycle E. G-CSF support (hazard ratio: 0.32, 0.24-0.43, p<0.001) was associated with lower NE recurrence. Pegfilgrastim seemed to offer the highest protection (hazard ratio; HR=0.23, 95% CI: 0.16-0.32; p<0.001). CONCLUSION: Secondary G-CSF prophylaxis has significant efficacy in reducing the incidence of NE and should be considered as a valuable option.

[Gastric metastasis from ovarian carcinoma revealed by a gastro-splenic perforation]. / Métastase gastrique d'un carcinome ovarien révélée par une perforation gastro-splénique.

Metastatic disease involving the stomach is unusual. We report the case of a gastric metastasis from ovarian cancer revealed by gastro-splenic perforation. The gastric metastasis was diagnosed 17 years after the diagnosis of primary cancer.