Review: Manipulation of follicle development to improve fertility of cattle in timed-artificial insemination programs

The development of an ovulatory follicle is a fundamental premise for any reproductive management program that aims to optimize fertility in cattle. Controlling follicular development comprises the synchronized emergence of a new follicular wave, selection and growth of the dominant follicle, and synchronized ovulation of a high-quality oocyte. All these follicular events, primarily driven by gonadotropin secretion, occur under a very dynamic hormonal environment. In this sense, controlling follicular development demands essentially a precise manipulation of the hormonal environment to modulate gonadotropin secretion. Furthermore, the effectiveness of hormonal manipulation strategies in the management of follicular development depends on specific particularities of each situation, which can vary widely according to genetic groups (Bos taurus vs Bos indicus), nutritional, metabolic, and reproductive status. In this regard, the constant search for the refined synchrony between the hormonal treatments and reproductive events, considering these distinctions and particularities, have provided valuable information that contributed to the development of efficient reproductive programs. This manuscript discusses the physiological bases behind the development of fine-tuned timed-artificial insemination protocols for beef and dairy cattle that resulted in great improvements in reproductive efficiency of beef and dairy herds.

Radiation Reaction Cooling as a Source of Anisotropic Momentum Distributions with Inverted Populations

Under the presence of strong electromagnetic fields and radiation reaction, plasmas develop anisotropic momentum distributions, characterized by a population inversion. This is a general property of collisionless plasmas when the radiation reaction force is taken into account. We study the case of a plasma in a strong magnetic field and demonstrate the development of ring momentum distributions. The timescales for ring formation are derived for this configuration. The analytical results for the ring properties and the timescales for ring formation are confirmed with particle-in-cell simulations. The resulting momentum distributions are kinetically unstable and are known to lead to coherent radiation emission in astrophysical plasmas and laboratory setups.

NEOTROPICAL FRESHWATER FISHES: A dataset of occurrence and abundance of freshwater fishes in the Neotropics

The Neotropical region hosts 4225 freshwater fish species, ranking first among the world's most diverse regions for freshwater fishes. Our NEOTROPICAL FRESHWATER FISHES data set is the first to produce a large-scale Neotropical freshwater fish inventory, covering the entire Neotropical region from Mexico and the Caribbean in the north to the southern limits in Argentina, Paraguay, Chile, and Uruguay. We compiled 185,787 distribution records, with unique georeferenced coordinates, for the 4225 species, represented by occurrence and abundance data. The number of species for the most numerous orders are as follows: Characiformes (1289), Siluriformes (1384), Cichliformes (354), Cyprinodontiformes (245), and Gymnotiformes (135). The most recorded species was the characid Astyanax fasciatus (4696 records). We registered 116,802 distribution records for native species, compared to 1802 distribution records for nonnative species. The main aim of the NEOTROPICAL FRESHWATER FISHES data set was to make these occurrence and abundance data accessible for international researchers to develop ecological and macroecological studies, from local to regional scales, with focal fish species, families, or orders. We anticipate that the NEOTROPICAL FRESHWATER FISHES data set will be valuable for studies on a wide range of ecological processes, such as trophic cascades, fishery pressure, the effects of habitat loss and fragmentation, and the impacts of species invasion and climate change. There are no copyright restrictions on the data, and please cite this data paper when using the data in publications.

Slowdown of interpenetration of two counterpropagating plasma slabs due to collective effects

The nonlinear evolution of electromagnetic instabilities driven by the interpenetration of two e^{-},e^{+} plasma clouds is explored using ab initio kinetic plasma simulations. We show that the plasma clouds slow down due to both oblique and Weibel generated electromagnetic fields, which deflect the particle trajectories, transferring bulk forward momentum into transverse momentum and thermal velocity spread. This process causes the flow velocity v_{inst} to decrease approximately by a factor of sqrt[1/3] in a time interval Δt_{αB}ω_{p}∼c/(v_{fl}sqrt[α_{B}]), where α_{B} is the magnetic equipartition parameter determined by the nonlinear saturation of the instabilities, v_{fl} is the initial flow speed, and ω_{p} is the plasma frequency. For the α_{B} measured in our simulations, Δt_{αB} is close to 10 times the instability growth time. We show that as long as the plasma slab length L>v_{fl}Δt_{αB}, the plasma flow is expected to slow down by a factor close to sqrt[1/3].

Weibel instability beyond bi-Maxwellian anisotropy

The shape of the anisotropic velocity distribution function, beyond the realm of strict Maxwellians can play a significant role in determining the evolution of the Weibel instability dictating the dynamics of self-generated magnetic fields. For non-Maxwellian distribution functions, we show that the direction of the maximum growth rate wave vector changes with shape. We investigate different laser-plasma interaction model distributions which show that their Weibel generated magnetic fields may require closer scrutiny beyond the second moment (temperature) anisotropy ratio characterization.

Kinetic instability in inductively oscillatory plasma equilibrium

A uniform in space, oscillatory in time plasma equilibrium sustained by a time-dependent current density is analytically and numerically studied resorting to particle-in-cell simulations. The dispersion relation is derived from the Vlasov equation for oscillating equilibrium distribution functions, and used to demonstrate that the plasma has an infinite number of unstable kinetic modes. This instability represents a kinetic mechanism for the decay of the initial mode of infinite wavelength (or equivalently null wave number), for which no classical wave breaking or Landau damping exists. The relativistic generalization of the instability is discussed. In this regime, the growth rate of the fastest growing unstable modes scales with γ_{T}^{-1/2}, where γ_{T} is the largest Lorentz factor of the plasma distribution. This result hints that this instability is not as severely suppressed for large Lorentz factor flows as purely streaming instabilities. The relevance of this instability in inductive electric field oscillations driven in pulsar magnetospheres is discussed.

Transition between Instability and Seeded Self-Modulation of a Relativistic Particle Bunch in Plasma

We use a relativistic ionization front to provide various initial transverse wakefield amplitudes for the self-modulation of a long proton bunch in plasma. We show experimentally that, with sufficient initial amplitude [≥(4.1±0.4)  MV/m], the phase of the modulation along the bunch is reproducible from event to event, with 3%-7% (of 2π) rms variations all along the bunch. The phase is not reproducible for lower initial amplitudes. We observe the transition between these two regimes. Phase reproducibility is essential for deterministic external injection of particles to be accelerated.

High-order harmonic generation in an electron-positron-ion plasma

The laser interaction with an electron-positron-ion mixed plasma is studied from the perspective of the associated high-order harmonic generation. For an idealized mixed plasma which is assumed with a sharp plasma-vacuum interface and uniform density distribution, when it is irradiated by a weakly relativistic laser pulse, well-defined signals at harmonics of the plasma frequency in the harmonic spectrum are observed. These characteristic signals are attributed to the inverse two-plasmon decay of the counterpropagating monochromatic plasma waves which are excited by the energetic electrons and the positron beam accelerated by the laser. Particle-in-cell simulations show the signal at twice the plasma frequency can be observed for a pair density as low as ∼10^{-5} of the plasma density. In the self-consistent scenario of pair production by an ultraintense laser striking a solid target, particle-in-cell simulations, which account for quantum electrodynamic effects (photon emission and pair production), show that dense (greater than the relativistically corrected critical density) and hot pair plasmas can be created. The harmonic spectrum shows weak low-order harmonics, indicating a high laser absorption due to quantum electrodynamic effects. The characteristic signals at harmonics of the plasma frequency are absent, because broadband plasma waves are excited due to the high plasma inhomogeneity introduced by the interaction. However, the high-frequency harmonics are enhanced due to the high-frequency modulations from the direct laser coupling with created pair plasmas.

Plasma Wakes Driven by Photon Bursts via Compton Scattering

Photon bursts with a wavelength smaller than the plasma interparticle distance can drive plasma wakes via Compton scattering. We investigate this fundamental process analytically and numerically for different photon frequencies, photon flux, and plasma magnetization. Our results show that Langmuir and extraordinary modes are driven efficiently when the photon energy density lies above a certain threshold. The interaction of photon bursts with magnetized plasmas is of distinguished interest as the generated extraordinary modes can convert into pure electromagnetic waves at the plasma-vacuum boundary. This could possibly be a mechanism for the generation of radio waves in astrophysical scenarios in the presence of intense sources of high energy photons.

Proton Bunch Self-Modulation in Plasma with Density Gradient

We study experimentally the effect of linear plasma density gradients on the self-modulation of a 400 GeV proton bunch. Results show that a positive or negative gradient increases or decreases the number of microbunches and the relative charge per microbunch observed after 10 m of plasma. The measured modulation frequency also increases or decreases. With the largest positive gradient we observe two frequencies in the modulation power spectrum. Results are consistent with changes in wakefields' phase velocity due to plasma density gradients adding to the slow wakefields' phase velocity during self-modulation growth predicted by linear theory.

New criteria for efficient Raman and Brillouin amplification of laser beams in plasma

Raman or Brillouin amplification of a laser beam in plasma has long been seen as a way to reach multi-PW powers in compact laser systems. However, no significant plasma-based Raman amplification of a laser pulse beyond 0.1 TW has been achieved in nearly 20 years, and only one report of Brillouin amplification beyond 1 TW. In this paper, we reveal novel non-linear criteria for the initial seed pulse that will finally open the door to efficient Raman and Brillouin amplification to petawatt powers and Joule-level energies. We show that the triple product of the coupling constant [Formula: see text], seed pulse duration [Formula: see text] and seed pulse amplitude a for the Raman seed pulse (or [Formula: see text] for Brillouin) must exceed a specific minimum threshold for efficient amplification. We also analyze the plasma-based Raman and Brillouin amplification experiments to date, and show that the seed pulses used in nearly all experiments are well below our new threshold, which explains the poor efficiency obtained in them. Finally, we analyze a recent Brillouin amplification experiment that used increased seed pulse power to obtain Joule-level amplification, and find excellent agreement with our theory.

0577 Cluster Analysis for the Association Between Obstructive Sleep Apnea Phenotypes: A Population-Based Longitudinal Study

Introduction

The identification of subgroups of obstructive sleep apnea (OSA) is critical to understand disease causality and ultimately develop optimal care strategies customized for each subgroup. In this sense, we aimed to perform a cluster analysis to identify subgroups of individuals with OSA based on clinical parameters. Furthermore, we aimed to analyze whether subgroups remain after 8 years.

Methods

We used data derived from the Sao Paulo Epidemiologic Sleep Study (EPISONO) cohort, which was followed over 8 years. All individuals underwent polysomnography, answered questionnaires and had their blood collected for biochemical exams. OSA was defined according to an AHI equal or greater than 15 events per hour. Cluster analysis was performed using latent class analysis (LCA).

Results

Of the 1,042 individuals in the EPISONO baseline cohort, 68.3% accepted to participate in the follow-up study (n=712). We were able to replicate the OSA 3-cluster solution observed in previous studies: disturbed sleep, minimally symptomatic and excessively sleepy in both baseline (35.5%, 45.4% and 19.1%, respectively) and follow-up studies (41.9%, 43.4% and 14.8%, respectively). 44.8% of the participants migrated clusters between the two evaluations and the factor associated with this was a greater delta-AHI (B=-0.033, df=1, p=0.003). The optimal cluster solution for our sample based on Bayesian information criterion (BIC) was 2 clusters for baseline (disturbed sleep and excessively sleepy) and 3 clusters for follow-up (disturbed sleep, minimally symptomatic and excessively sleepy).

Conclusion

The results found replicate and confirm previously identified clinical clusters in OSA even in a longitudinal analysis.

Support

This work was supported by grants from AFIP, FAPESP and CAPES.

Prospect of Studying Nonperturbative QED with Beam-Beam Collisions

We demonstrate the experimental feasibility of probing the fully nonperturbative regime of quantum electrodynamics with a 100 GeV-class particle collider. By using tightly compressed and focused electron beams, beamstrahlung radiation losses can be mitigated, allowing the particles to experience extreme electromagnetic fields. Three-dimensional particle-in-cell simulations confirm the viability of this approach. The experimental forefront envisaged has the potential to establish a novel research field and to stimulate the development of a new theoretical methodology for this yet unexplored regime of strong-field quantum electrodynamics.

Experimental Observation of Proton Bunch Modulation in a Plasma at Varying Plasma Densities

We give direct experimental evidence for the observation of the full transverse self-modulation of a long, relativistic proton bunch propagating through a dense plasma. The bunch exits the plasma with a periodic density modulation resulting from radial wakefield effects. We show that the modulation is seeded by a relativistic ionization front created using an intense laser pulse copropagating with the proton bunch. The modulation extends over the length of the proton bunch following the seed point. By varying the plasma density over one order of magnitude, we show that the modulation frequency scales with the expected dependence on the plasma density, i.e., it is equal to the plasma frequency, as expected from theory.

Experimental Observation of Plasma Wakefield Growth Driven by the Seeded Self-Modulation of a Proton Bunch

We measure the effects of transverse wakefields driven by a relativistic proton bunch in plasma with densities of 2.1×10^{14} and 7.7×10^{14}  electrons/cm^{3}. We show that these wakefields periodically defocus the proton bunch itself, consistently with the development of the seeded self-modulation process. We show that the defocusing increases both along the bunch and along the plasma by using time resolved and time-integrated measurements of the proton bunch transverse distribution. We evaluate the transverse wakefield amplitudes and show that they exceed their seed value (<15  MV/m) and reach over 300  MV/m. All these results confirm the development of the seeded self-modulation process, a necessary condition for external injection of low energy and acceleration of electrons to multi-GeV energy levels.

Pollen as a component of the diet of Doru luteipes (Scudder, 1876) (Dermaptera: Forficulidade)

The properties of maize pollen in the diet of Doru luteipes were determined by biological responses of the predator feeding on natural preys and artificial diet. The biological parameters of D. luteipes fed on Spodoptera frugiperda (Smith, 1797) eggs, maize pollen, Rhopalosiphum maidis (Fitch, 1856) + maize pollen and R. maidis were assessed. The effect of pollen on artificial diet on the biological variables of the predator nymphs and adults were also evaluated. Time span of nymphal development was greater for D. luteipes exclusively fed on earwigs, with the lowest rate of nymph survival. However, maize pollen plus earwigs in the diet provided the predator´s highest survival rate, whilst percentage of fertile females was double when fed on diets composed of S. frugiperda and R. maidis eggs. Development period decreased when D. luteipes nymphs consumed artificial diet plus pollen but there were high fecundity rates (number of laying/female and total egg/female) and a greater percentage of fertile females when they were fed on maize pollen.

Acceleration of electrons in the plasma wakefield of a proton bunch

High-energy particle accelerators have been crucial in providing a deeper understanding of fundamental particles and the forces that govern their interactions. To increase the energy of the particles or to reduce the size of the accelerator, new acceleration schemes need to be developed. Plasma wakefield acceleration^1–5, in which the electrons in a plasma are excited, leading to strong electric fields (so called ‘wakefields’), is one such promising acceleration technique. Experiments have shown that an intense laser pulse^6–9 or electron bunch^10,11 traversing a plasma can drive electric fields of tens of gigavolts per metre and above—well beyond those achieved in conventional radio-frequency accelerators (about 0.1 gigavolt per metre). However, the low stored energy of laser pulses and electron bunches means that multiple acceleration stages are needed to reach very high particle energies^5,12. The use of proton bunches is compelling because they have the potential to drive wakefields and to accelerate electrons to high energy in a single acceleration stage¹³. Long, thin proton bunches can be used because they undergo a process called self-modulation^14–16, a particle–plasma interaction that splits the bunch longitudinally into a series of high-density microbunches, which then act resonantly to create large wakefields. The Advanced Wakefield (AWAKE) experiment at CERN^17–19 uses high-intensity proton bunches—in which each proton has an energy of 400 gigaelectronvolts, resulting in a total bunch energy of 19 kilojoules—to drive a wakefield in a ten-metre-long plasma. Electron bunches are then injected into this wakefield. Here we present measurements of electrons accelerated up to two gigaelectronvolts at the AWAKE experiment, in a demonstration of proton-driven plasma wakefield acceleration. Measurements were conducted under various plasma conditions and the acceleration was found to be consistent and reliable. The potential for this scheme to produce very high-energy electron bunches in a single accelerating stage²⁰ means that our results are an important step towards the development of future high-energy particle accelerators^21,22.

Electron acceleration to very high energies is achieved in a single step by injecting electrons into a ‘wake’ of charge created in a 10-metre-long plasma by speeding long proton bunches.

Fully kinetic Biermann battery and associated generation of pressure anisotropy

The dynamical evolution of a fully kinetic, collisionless system with imposed background density and temperature gradients is investigated analytically. The temperature gradient leads to the generation of temperature anisotropy, with the temperature along the gradient becoming larger than that in the direction perpendicular to it. This causes the system to become unstable to pressure anisotropy driven instabilities, dominantly to the electron Weibel instability. When both density and temperature gradients are present and nonparallel to each other, we obtain a Biermann-like linear-in-time magnetic field growth. Accompanying particle-in-cell numerical simulations are shown to confirm our analytical results.

Collimated protons accelerated from an overdense gas jet irradiated by a 1 µm wavelength high-intensity short-pulse laser

We have investigated proton acceleration in the forward direction from a near-critical density hydrogen gas jet target irradiated by a high intensity (10¹⁸ W/cm²), short-pulse (5 ps) laser with wavelength of 1.054 μm. We observed the signature of the Collisionless Shock Acceleration mechanism, namely quasi-monoenergetic proton beams with small divergence in addition to the more commonly observed electron-sheath driven proton acceleration. The proton energies we obtained were modest (~MeV), but prospects for improvement are offered through further tailoring the gas jet density profile. Also, we observed that this mechanism is very robust in producing those beams and thus can be considered as a future candidate in laser-driven ion sources driven by the upcoming next generation of multi-PW near-infrared lasers.

Stable multi-GeV electron accelerator driven by waveform-controlled PW laser pulses

The achievable energy and the stability of accelerated electron beams have been the most critical issues in laser wakefield acceleration. As laser propagation, plasma wave formation and electron acceleration are highly nonlinear processes, the laser wakefield acceleration (LWFA) is extremely sensitive to initial experimental conditions. We propose a simple and elegant waveform control method for the LWFA process to enhance the performance of a laser electron accelerator by applying a fully optical and programmable technique to control the chirp of PW laser pulses. We found sensitive dependence of energy and stability of electron beams on the spectral phase of laser pulses and obtained stable 2-GeV electron beams from a 1-cm gas cell of helium. The waveform control technique for LWFA would prompt practical applications of centimeter-scale GeV-electron accelerators to a compact radiation sources in the x-ray and γ-ray regions.

Seeded QED cascades in counterpropagating laser pulses

The growth rates of seeded QED cascades in counterpropagating lasers are calculated with first-principles two- and three-dimensional QED-PIC (particle-in-cell) simulations. The dependence of the growth rate on the laser polarization and intensity is compared with analytical models that support the findings of the simulations. The models provide insight regarding the qualitative trend of the cascade growth when the intensity of the laser field is varied. A discussion about the cascade's threshold is included, based on the analytical and numerical results. These results show that relativistic pair plasmas and efficient conversion from laser photons to γ rays can be observed with the typical intensities planned to operate on future ultraintense laser facilities such as ELI or Vulcan.

High Orbital Angular Momentum Harmonic Generation

We identify and explore a high orbital angular momentum (OAM) harmonics generation and amplification mechanism that manipulates the OAM independently of any other laser property, by preserving the initial laser wavelength, through stimulated Raman backscattering in a plasma. The high OAM harmonics spectra can extend at least up to the limiting value imposed by the paraxial approximation. We show with theory and particle-in-cell simulations that the orders of the OAM harmonics can be tuned according to a selection rule that depends on the initial OAM of the interacting waves. We illustrate the high OAM harmonics generation in a plasma using several examples including the generation of prime OAM harmonics. The process can also be realized in any nonlinear optical Kerr media supporting three-wave interactions.

Physical Mechanism of the Transverse Instability in Radiation Pressure Ion Acceleration

The transverse stability of the target is crucial for obtaining high quality ion beams using the laser radiation pressure acceleration (RPA) mechanism. In this Letter, a theoretical model and supporting two-dimensional (2D) particle-in-cell (PIC) simulations are presented to clarify the physical mechanism of the transverse instability observed in the RPA process. It is shown that the density ripples of the target foil are mainly induced by the coupling between the transverse oscillating electrons and the quasistatic ions, a mechanism similar to the oscillating two stream instability in the inertial confinement fusion research. The predictions of the mode structure and the growth rates from the theory agree well with the results obtained from the PIC simulations in various regimes, indicating the model contains the essence of the underlying physics of the transverse breakup of the target.

Transverse electron-scale instability in relativistic shear flows

Electron-scale surface waves are shown to be unstable in the transverse plane of a sheared flow in an initially unmagnetized collisionless plasma, not captured by (magneto)hydrodynamics. It is found that these unstable modes have a higher growth rate than the closely related electron-scale Kelvin-Helmholtz instability in relativistic shears. Multidimensional particle-in-cell simulations verify the analytic results and further reveal the emergence of mushroomlike electron density structures in the nonlinear phase of the instability, similar to those observed in the Rayleigh Taylor instability despite the great disparity in scales and different underlying physics. This transverse electron-scale instability may play an important role in relativistic and supersonic sheared flow scenarios, which are stable at the (magneto)hydrodynamic level. Macroscopic (≫c/ωpe) fields are shown to be generated by this microscopic shear instability, which are relevant for particle acceleration, radiation emission, and to seed magnetohydrodynamic processes at long time scales.

All-optical radiation reaction at 10²¹ W/cm²

Using full-scale 3D particle-in-cell simulations we show that the radiation reaction dominated regime can be reached in an all-optical configuration through the collision of a ~1 GeV laser wakefield accelerated electron bunch with a counterpropagating laser pulse. In this configuration the radiation reaction significantly reduces the energy of the particle bunch, thus providing clear experimental signatures for the process with currently available lasers. We also show that the transition between the classical and quantum radiation reaction could be investigated in the same configuration with laser intensities of 10²³ W/cm².

Electromagnetic field generation in the downstream of electrostatic shocks due to electron trapping

A new magnetic field generation mechanism in electrostatic shocks is found, which can produce fields with magnetic energy density as high as 0.01 of the kinetic energy density of the flows on time scales ∼10(4)ωpe-1. Electron trapping during the shock formation process creates a strong temperature anisotropy in the distribution function, giving rise to the pure Weibel instability. The generated magnetic field is well confined to the downstream region of the electrostatic shock. The shock formation process is not modified, and the features of the shock front responsible for ion acceleration, which are currently probed in laser-plasma laboratory experiments, are maintained. However, such a strong magnetic field determines the particle trajectories downstream and has the potential to modify the signatures of the collisionless shock.

The genus Dasineura Rondani, 1840 (Diptera, Cecidomyiidae) in Brazil

Dasineura (Diptera, Cecidomyiidae) is the gall midge genus with the highest number of known species (466 throughout the world). Only 39 species have been described from the Neotropics, being 10 from Brazil. Many records of not determined species are found in the literature. Furthermore, many unidentified specimens are deposited in the Cecidomyiidae Collection of the Museu Nacional/UFRJ, which comprises material from several Brazilian biomes. This paper provides these data, presents new records of localities and host plants, and discusses the representativeness of Dasineura in Brazil. The results point to the occurrence of 32 species in Brazil and show that the genus is much more diversified than previous knowledge indicates.

Magnetic-field generation and amplification in an expanding plasma

Particle-in-cell simulations are used to investigate the formation of magnetic fields B in plasmas with perpendicular electron density and temperature gradients. For system sizes L comparable to the ion skin depth d(i), it is shown that B ∼ d(i)/L, consistent with the Biermann battery effect. However, for large L/d(i), it is found that the Weibel instability (due to electron temperature anisotropy) supersedes the Biermann battery as the main producer of B. The Weibel-produced fields saturate at a finite amplitude (plasma β ≈ 100), independent of L. The magnetic energy spectra below the electron Larmor radius scale are well fitted by the power law with slope -16/3, as predicted by Schekochihin et al. [Astrophys. J. Suppl. Ser. 182, 310 (2009)].

Exploring the nature of collisionless shocks under laboratory conditions

Collisionless shocks are pervasive in astrophysics and they are critical to understand cosmic ray acceleration. Laboratory experiments with intense lasers are now opening the way to explore and characterise the underlying microphysics, which determine the acceleration process of collisionless shocks. We determine the shock character - electrostatic or electromagnetic - based on the stability of electrostatic shocks to transverse electromagnetic fluctuations as a function of the electron temperature and flow velocity of the plasma components, and we compare the analytical model with particle-in-cell simulations. By making the connection with the laser parameters driving the plasma flows, we demonstrate that shocks with different and distinct underlying microphysics can be explored in the laboratory with state-of-the-art laser systems.

Morphometric evaluation of nitric oxide synthase isoforms and their cytokine regulators predict pulmonary dysfunction and survival in systemic sclerosis

Because histopathological changes in the lungs of patients with systemic sclerosis (SSc) are consistent with alveolar and vessel cell damage, we presume that this interaction can be characterized by analyzing the expression of proteins regulating nitric oxide (NO) and plasminogen activator inhibitor-1 (PAI-1) synthesis. To validate the importance of alveolar-vascular interactions and to explore the quantitative relationship between these factors and other clinical data, we studied these markers in 23 cases of SSc nonspecific interstitial pneumonia (SSc-NSIP). We used immunohistochemistry and morphometry to evaluate the amount of cells in alveolar septa and vessels staining for NO synthase (NOS) and PAI-1, and the outcomes of our study were cellular and fibrotic NSIP, pulmonary function tests, and survival time until death. General linear model analysis demonstrated that staining for septal inducible NOS (iNOS) related significantly to staining of septal cells for interleukin (IL)-4 and to septal IL-13. In univariate analysis, higher levels of septal and vascular cells staining for iNOS were associated with a smaller percentage of septal and vascular cells expressing fibroblast growth factor and myofibroblast proliferation, respectively. Multivariate Cox model analysis demonstrated that, after controlling for SSc-NSIP histological patterns, just three variables were significantly associated with survival time: septal iNOS (P=0.04), septal IL-13 (P=0.03), and septal basic fibroblast growth factor (bFGF; P=0.02). Augmented NOS, IL-13, and bFGF in SSc-NSIP histological patterns suggest a possible functional role for iNOS in SSc. In addition, the extent of iNOS, PAI-1, and IL-4 staining in alveolar septa and vessels provides a possible independent diagnostic measure for the degree of pulmonary dysfunction and fibrosis with an impact on the survival of patients with SSc.

dc-Magnetic-field generation in unmagnetized shear flows

The generation of dc magnetic fields in unmagnetized electron-ion shear flows is shown to be associated to either initial thermal effects or the onset of electron-scale shear instabilities, in particular the cold Kelvin-Helmholtz instability. This mechanism, intrinsic to shear gradients on the electron scale, is described through a kinetic model that predicts the growth and the saturation of the dc field in both scenarios. The theoretical results are confirmed by multidimensional particle-in-cell simulations, demonstrating the formation of long-lived magnetic fields (t~100's ω(pi)(-1)) along the full longitudinal extent of the shear layer, with a typical transverse width of √[γ(0)]c/ω(pe), reaching magnitudes eB(dc)/m(e)cω(pe)~β(0)√[γ(0)] for an initial sharp shear. The case of an initial smooth shear is also discussed.

Relativistic generalization of formation and ion-reflection conditions in electrostatic shocks

The theoretical model by Sorasio et al. [Phys. Rev. Lett. 96, 045005 (2006)] for the steady state Mach number of electrostatic shocks formed in the interaction of two plasma slabs of arbitrary density and temperature is generalized for relativistic electron and nonrelativistic ion temperatures. We find that the relativistic correction leads to lower Mach numbers and as a consequence ions are reflected with lower energies. The steady state bulk velocity of the downstream population is introduced as an additional parameter to describe the transition between the minimum and maximum Mach numbers that is dependent on the initial density and temperature ratios. In order to transform the solitonlike solution in the upstream region into a shock, a population of reflected ions is considered and differences from a zero-ion temperature model are discussed.

Laser-driven shock acceleration of monoenergetic ion beams

We show that monoenergetic ion beams can be accelerated by moderate Mach number collisionless, electrostatic shocks propagating in a long scale-length exponentially decaying plasma profile. Strong plasma heating and density steepening produced by an intense laser pulse near the critical density can launch such shocks that propagate in the extended plasma at high velocities. The generation of a monoenergetic ion beam is possible due to the small and constant sheath electric field associated with the slowly decreasing density profile. The conditions for the acceleration of high-quality, energetic ion beams are identified through theory and multidimensional particle-in-cell simulations. The scaling of the ion energy with laser intensity shows that it is possible to generate ~200 MeV proton beams with state-of-the-art 100 TW class laser systems.

Ion motion in self-modulated plasma wakefield accelerators

The effects of plasma ion motion in self-modulated plasma-based accelerators are examined. An analytical model describing ion motion in the narrow beam limit is developed and confirmed through multidimensional particle-in-cell simulations. It is shown that the ion motion can lead to the early saturation of the self-modulation instability and to the suppression of the accelerating gradients. This can reduce the total energy that can be transformed into kinetic energy of accelerated particles. For the parameters of future proton-driven plasma accelerator experiments, the ion dynamics can have a strong impact. Possible methods to mitigate the effects of the ion motion in future experiments are demonstrated.

Weibel-instability-mediated collisionless shocks in the laboratory with ultraintense lasers

The formation of nonrelativistic collisionless shocks in the laboratory with ultrahigh intensity lasers is studied via ab initio multidimensional particle-in-cell simulations. The microphysics behind shock formation and dissipation and the detailed shock structure are analyzed, illustrating that the Weibel instability plays a crucial role in the generation of strong subequipartition magnetic fields that isotropize the incoming flow and lead to the formation of a collisionless shock, similar to what occurs in astrophysical scenarios. The possibility of generating such collisionless shocks in the laboratory opens the way to the direct study of the physics associated with astrophysical shocks.

Production of picosecond, kilojoule, and petawatt laser pulses via Raman amplification of nanosecond pulses

Raman amplification in plasma has been promoted as a means of compressing picosecond optical laser pulses to femtosecond duration to explore the intensity frontier. Here we show for the first time that it can be used, with equal success, to compress laser pulses from nanosecond to picosecond duration. Simulations show up to 60% energy transfer from pump pulse to probe pulse, implying that multikilojoule ultraviolet petawatt laser pulses can be produced using this scheme. This has important consequences for the demonstration of fast-ignition inertial confinement fusion.

Mechanism of generating fast electrons by an intense laser at a steep overdense interface

The acceleration and heating of electrons by an intense laser normally incident on a steep overdense plasma interface is investigated using the particle-in-cell code osiris. Energetic electrons are generated by the laser's electric field in the vacuum region within λ/4 of the surface. Only those electrons which originate within the plasma with a sufficiently large transverse momentum can escape the plasma. This mechanism relies on the standing wave structure created by the incoming and reflected wave and is therefore very different for linear and circularly polarized light.

Magnetic control of particle injection in plasma based accelerators

The use of an external transverse magnetic field to trigger and to control electron self-injection in laser- and particle-beam driven wakefield accelerators is examined analytically and through full-scale particle-in-cell simulations. A magnetic field can relax the injection threshold and can be used to control main output beam features such as charge, energy, and transverse dynamics in the ion channel associated with the plasma blowout. It is shown that this mechanism could be studied using state-of-the-art magnetic fields in next generation plasma accelerator experiments.

All-optical steering of laser-wakefield-accelerated electron beams

We investigate the influence of a tilted laser-pulse-intensity front on laser-wakefield acceleration. Such asymmetric light pulses may be exploited to obtain control over the electron-bunch-pointing direction and in our case allowed for reproducible electron-beam steering in an all-optical way within an 8 mrad opening window with respect to the initial laser axis. We also discovered evidence of collective electron-betatron oscillations due to off-axis electron injection into the wakefield induced by a pulse-front tilt. These findings are supported by 3D particle-in-cell simulations.

Self-guided laser wakefield acceleration beyond 1 GeV using ionization-induced injection

The concepts of matched-beam, self-guided laser propagation and ionization-induced injection have been combined to accelerate electrons up to 1.45 GeV energy in a laser wakefield accelerator. From the spatial and spectral content of the laser light exiting the plasma, we infer that the 60 fs, 110 TW laser pulse is guided and excites a wake over the entire 1.3 cm length of the gas cell at densities below 1.5 × 10(18) cm(-3). High-energy electrons are observed only when small (3%) amounts of CO2 gas are added to the He gas. Computer simulations confirm that it is the K-shell electrons of oxygen that are ionized and injected into the wake and accelerated to beyond 1 GeV energy.

Measurements of the critical power for self-injection of electrons in a laser wakefield accelerator

A laser wakefield acceleration study has been performed in the matched, self-guided, blowout regime producing 720 +/- 50 MeV quasimonoenergetic electrons with a divergence Deltatheta_{FWHM} of 2.85 +/- 0.15 mrad using a 10 J, 60 fs 0.8 microm laser. While maintaining a nearly constant plasma density (3 x 10{18} cm{-3}), the energy gain increased from 75 to 720 MeV when the plasma length was increased from 3 to 8 mm. Absolute charge measurements indicate that self-injection of electrons occurs when the laser power P exceeds 3 times the critical power P{cr} for relativistic self-focusing and saturates around 100 pC for P/P{cr} > 5. The results are compared with both analytical scalings and full 3D particle-in-cell simulations.

Near-GeV acceleration of electrons by a nonlinear plasma wave driven by a self-guided laser pulse

The acceleration of electrons to approximately 0.8 GeV has been observed in a self-injecting laser wakefield accelerator driven at a plasma density of 5.5x10(18) cm(-3) by a 10 J, 55 fs, 800 nm laser pulse in the blowout regime. The laser pulse is found to be self-guided for 1 cm (>10zR), by measurement of a single filament containing >30% of the initial laser energy at this distance. Three-dimensional particle in cell simulations show that the intensity within the guided filament is amplified beyond its initial focused value to a normalized vector potential of a0>6, thus driving a highly nonlinear plasma wave.

Statistical kinetic treatment of relativistic binary collisions

In particle-based algorithms, the effect of binary collisions is commonly described in a statistical way, using Monte Carlo techniques. It is shown that, in the relativistic regime, stringent constraints should be considered on the sampling of particle pairs for collision, which are critical to ensure physically meaningful results, and that nonrelativistic sampling criteria (e.g., uniform random pairing) yield qualitatively wrong results, including equilibrium distributions that differ from the theoretical Jüttner distribution. A general procedure for relativistically consistent algorithms is provided, and verified with three-dimensional Monte Carlo simulations, thus opening the way to the numerical exploration of the statistical properties of collisional relativistic systems.

Beam loading in the nonlinear regime of plasma-based acceleration

A theory that describes how to load negative charge into a nonlinear, three-dimensional plasma wakefield is presented. In this regime, a laser or an electron beam blows out the plasma electrons and creates a nearly spherical ion channel, which is modified by the presence of the beam load. Analytical solutions for the fields and the shape of the ion channel are derived. It is shown that very high beam-loading efficiency can be achieved, while the energy spread of the bunch is conserved. The theoretical results are verified with the particle-in-cell code OSIRIS.

Spontaneous generation of self-organized solitary wave structures at earth's magnetopause

Spontaneous formation of solitary wave structures has been observed in Earth's magnetopause, and is shown to be caused by the breakup of a zonal flow by the action of drift wave turbulence. Here we show matched observations and modeling of coherent, large-scale solitary electrostatic structures, generated during the interaction of short-scale drift wave turbulence and zonal flows at the Earth's magnetopause. The observations were made by the Cluster spacecraft and the numerical modeling was performed using the wave-kinetic approach to drift wave-zonal flow interactions. Good agreement between observations and simulations has been found, thus explaining the emergence of the observed solitary structures as well as confirming earlier theoretical predictions of their existence.

White-light parametric instabilities in plasmas

Parametric instabilities driven by partially coherent radiation in plasmas are described by a generalized statistical Wigner-Moyal set of equations, formally equivalent to the full wave equation, coupled to the plasma fluid equations. A generalized dispersion relation for stimulated Raman scattering driven by a partially coherent pump field is derived, revealing a growth rate dependence, with the coherence width sigma of the radiation field, scaling with 1/sigma for backscattering (three-wave process), and with 1/sigma1/2 for direct forward scattering (four-wave process). Our results demonstrate the possibility to control the growth rates of these instabilities by properly using broadband pump radiation fields.