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We use the full NASA Van Allen Probes mission (2012–2019) to extract the electron plasma density from the Electric and Magnetic Field Instrument Suite and Integrated Science (EMFISIS) and Electric Field and Waves (EFW) instruments and discuss the evolution of the plasmasphere. We generate new statistics including mean and standard deviations of the plasma density with respect to L‐shell, magnetic local time (MLT), and various geomagnetic indices. These statistics are generated to be applied in radiation belt physics and space weather codes (with fits provided). The mean plasmasphere is circular around Earth with respect to MLT for Kp < 1. The mean 100 cm−3level line is above L = 5 and mean 10 cm−3level expands above the Van Allen Probes apogee for Kp < 1. The outer electron belt lies within the plasmasphere for 60% of all times. As activity increases (Kp > 2), a gradual MLT asymmetry forms with higher mean density in the afternoon sector due to plumes expanding outward. Conversely, the mean density decreases on the dawn and night sectors. The mean density is between ∼500 and ∼50 cm−3between L ∼ 4 and L ∼ 6 during quiet and moderately active times (Kp < 3), representing ∼80% of all times. Statistics in regions of high density below L = 2 are underdefined for intense activity. The highest standard deviation of density represents a factor 2.5 to 3 times the mean above L = 5 and for active times. We find the percent difference between the EFW and EMFISIS densities is bounded by ±20% for quiet and moderate activity (Kp < 5) and goes up to ±100% for extreme activity. The Earth's plasmasphere, discovered in the 1950s, is a region of cold plasma made of ions and electrons of a few electronvolts in energy, originating from upwelling ionized gas from the ionosphere and forming a rotating torus around the Earth. The radial profile of the electron cold plasma density within the plasmasphere decays from 10,000 electrons per cubic centimeter at ∼1,000 km altitude to 10s electrons per cubic centimeter at its outer edge, sometimes exceeding ∼36,000 km in altitude at the equator. The state of the plasmasphere is highly dependent on geomagnetic conditions, with geomagnetic storms and substorms eroding parts of this plasma. Here, we analyze 7 years of NASA Van Allen Probes measurements of the electron plasma density and generate statistics with respect to L‐shell, magnetic local time, and geomagnetic indices. In this way, we show statistical variations of the plasmasphere, a strong magnetic local time dependence, and erosion with increasing geomagnetic activity. New mean electron densities and their standard deviation are generated and fitted with model functions that can be incorporated into space weather codes. This is important because the electron density is a key parameter influencing the strength of wave‐particle interactions that accelerate and scatter energetic particles in the inner magnetosphere. Generation of new statistics of mean and standard deviation of the plasma density from Electric Field and Waves and Electric and Magnetic Field Instrument Suite and Integrated Science of RBSP for the whole missionEmpirical density models made of fits are provided versus L‐shell, magnetic local time (MLT), and geomagnetic indices to be used in radiation belt codesAn extensive analysis of the cold plasma statistics is provided with respect to L‐shell, MLT, and geomagnetic activity Generation of new statistics of mean and standard deviation of the plasma density from Electric Field and Waves and Electric and Magnetic Field Instrument Suite and Integrated Science of RBSP for the whole mission Empirical density models made of fits are provided versus L‐shell, magnetic local time (MLT), and geomagnetic indices to be used in radiation belt codes An extensive analysis of the cold plasma statistics is provided with respect to L‐shell, MLT, and geomagnetic activity

In the processes related to the development of cancer, there are different genetic and epigenetic events involved that result in structural changes of the affected cells. In the early stages of the disease, these changes occur at the nanoscale, remaining undetectable by conventional light microscopy, due to diffraction-limited resolution (∼250 - 550 nm). In this sense, a technique termed partial wave spectroscopy (PWS) allows the detection of these nanostructural changes by measuring a statistical parameter called disorder strength (L_d). PWS uses a combination of a tunable filter and a camera to acquire the backscattering spectra for each pixel on the image. In this paper, we study and validate the possibility of obtaining a qualitative measurement of the disorder using the spectrum of the averaged spatial information. Instead of using spatial information and measuring sequentially spectral ranges, we measure the backscattered signal gathered by an optical fiber by means of a spectrograph. This will allow this method to be applied in systems where it is not possible to acquire a complete high resolution image for many spectral bands, while significantly enhancing speed.

We propose a new method that uses the World‐Wide Lightning Location Network (WWLLN) to estimate both the local and the drift lightning power density at the Van Allen Probes footprints during 4.3 years (~2 × 108strokes.). The ratio of the drift power density to the local power density defines a time‐resolved WWLLN‐based model of lightning‐generated wave (LGW) power density ratio, RWWLLN. RWWLLNis computed every ~34 s. This ratio multiplied by the time‐resolved LGW intensity measured by the Probes allows direct computation of pitch angle diffusion coefficients used in radiation belt codes. Statistical analysis shows the median power density ratio is R̂WWLLN=0.3−4over the Americas. Elsewhere, R̂WWLLN>1in general. Over oceans, R̂WWLLNis larger than ~10. R̂WWLLNvaries with season, R̂WWLLN~ 2.5 from winter to summer. The yearly‐median R̂WWLLNdecays as R̂WWLLN~9.9/L0.91. The strong geographical and temporal variation should be kept in assessing effects in space. RWWLLN> 1suggests significant LGW effects in the inner belt. Lightning flashes strongly emit electromagnetic lightning‐generated waves (LGW). This radiation propagates inside the Earth‐Ionosphere waveguide and escapes into the magnetosphere. Trapped electrons originating from solar eruptions bounce and drift around Earth magnetic field lines. They can be scattered into the atmosphere by any resonant interactions with surrounding LGW that causes diffusion of the electron velocity. Computing accurately the electron diffusion is critical for space weather. This diffusion is proportional to the LGW drift intensity, that is, the LGW intensity affecting the electron along its drift around the Earth, which is not directly measurable since many satellites would be required. Here, we propose a new method that uses the ground‐based World‐Wide Lightning Location Network (WWLLN) to estimate both the local and the drift lightning power density at the Van Allen Probes (RBSP) footprints. Their ratio defines a time‐resolved WWLLN‐based LGW power density ratio, RWWLLN, which multiplied by the local LGW intensity measured by RBSP allows direct computation of LGW diffusion required in space weather codes. Statistical maps of power density and ratios are discussed. We conclude that the large geographical and seasonal variability is important to keep in assessing effects in space and that RWWLLN> 1suggests significant LGW effects in the inner belt. Local time resolved and statistics of local (Pl) and drift (Pd) lightning power density and the ratio (R= Pd/Pl) for radiation belt codesPower density ratios indicate major local lightning activity over the Americas ( R̂WWLLN~<1) and weaker local activity elsewhere ( R̂WWLLN>1)Large variability of lightning suggests to use time‐resolved power density ratios at fixed Lshell in radiation belt codes

A statistical study was conducted of Earth's radiation belt electron response to geomagnetic storms using NASA's Van Allen Probes mission. Data for electrons with energies ranging from 30 keV to 6.3 MeV were included and examined as a function of L‐shell, energy, and epoch time during 110 storms with SYM‐H≤−50 nT during September 2012 to September 2017 (inclusive). The radiation belt response revealed clear energy and L‐shell dependencies, with tens of keV electrons enhanced at all L‐shells (2.5 ≤ L ≤ 6) in all storms during the storm commencement and main phase and then quickly decaying away during the early recovery phase, low hundreds of keV electrons enhanced at lower L‐shells (~3 ≤ L ≤ ~4) in upward of 90% of all storms and then decaying gradually during the recovery phase, and relativistic electrons throughout the outer belt showing main phase dropouts with subsequent and generally unpredictable levels of replenishment during the recovery phase. Compared to prestorm levels, electrons with energies >1 MeV also revealed a marked increase in likelihood of a depletion at all L‐shells through the outer belt (3.5 ≤ L ≤ 6). Additional statistics were compiled revealing the storm time morphology of the radiation belts, confirming the aforementioned qualitative behavior. Considering storm drivers in the solar wind: storms driven by coronal mass ejection (CME) shocks/sheaths and CME ejecta only are most likely to result in a depletion of >1‐MeV electrons throughout the outer belt, while storms driven by full CMEs and stream interaction regions are most likely to produce an enhancement of MeV electrons at lower (L < ~5) and higher (L > ~4.5) L‐shells, respectively. CME sheaths intriguingly result in a distinct enhancement of ~1‐MeV electrons around L~5.5, and on average, CME sheaths and stream interaction regions result in double outer belt structures. A statistical model of electron radiation belt response to storms as a function of energy and L‐shell is developedStorm‐time morphology of the electron radiation belts is qualitatively predictableResults are better organized when the solar wind drivers of storms are identified

The evolution of the radiation belts in L‐shell (L), energy (E), and equatorial pitch angle (α0) is analyzed during the calm 11‐day interval (4–15 March) following the 1 March 2013 storm. Magnetic Electron and Ion Spectrometer (MagEIS) observations from Van Allen Probes are interpreted alongside 1D and 3D Fokker‐Planck simulations combined with consistent event‐driven scattering modeling from whistler mode hiss waves. Three (L, E, α0) regions persist through 11 days of hiss wave scattering; the pitch angle‐dependent inner belt core (L~ <2.2 and E< 700 keV), pitch angle homogeneous outer belt low‐energy core (L> ~5 and E~ < 100 keV), and a distinct pocket of electrons (L~ [4.5, 5.5] and E~ [0.7, 2] MeV). The pitch angle homogeneous outer belt is explained by the diffusion coefficients that are roughly constant for α0~ <60°, E> 100 keV, 3.5 < L< Lpp~ 6. Thus, observed unidirectional flux decays can be used to estimate local pitch angle diffusion rates in that region. Top‐hat distributions are computed and observed at L~ 3–3.5 and E= 100–300 keV. We study the evolution of the radiation belts during quiet geomagnetic times from satellite observations and numerical codes. We reach a global understanding of the trapped electrons variation with time, space, energy, and pitch angle (the angle of the velocity vector with the magnetic field). We exhibit three stable regions, which are less sensitive to scattering from hiss waves, while, on the other hand, hiss causes flux decay over 12 days that forms the slot region between the inner and outer belt. The existing theory explains why the outer belt electron decay is independent of pitch angle but dependent upon energy. This implies that satellite observations can reveal local pitch angle diffusion rates, themselves intimately connected with the wave properties. Thus, a connection is made between observed wave properties and observed/computed scattered electron flux, consistent with theory. Regions where the flux is pitch angle dependent are isolated in the low‐energy slot region where we show that the real shape is a smoothed version of the ideal top‐hat distribution computed from theory. The impact of this work is improved understanding of the belt evolution for space weather prediction, with a proposed event‐driven method that accurately (within ×2) predicts the electron flux decay after storms. Global computations of the (L, E, α0) structure of the evolving radiation belt during quiet times agree well with observationsThe inner belt decay is pitch angle dependent, while the outer belt is much more homogeneous with two distinct (L, E) regionsThe homogeneity of the pitch angle diffusion coefficient due to hiss waves explains the uniform outer belt decay and why 1D and 3D simulations agree

We present simulations of the loss of radiation belt electrons by resonant pitch angle diffusion caused by whistler mode hiss waves for March 2013. Pitch angle diffusion coefficients are computed from the wave properties and the ambient plasma data obtained by the Van Allen Probes with a resolution of 8 h and 0.1 Lshell. Loss rates follow a complex dynamic structure, imposed by the wave and plasma properties. Hiss effects can be strong, with minimum lifetimes (of ~1 day) moving from energies of ~100 keV at L~ 5 up to ~2 MeV at L~ 2 and stop abruptly, similarly to the observed energy‐dependent inner belt edge. Periods when the plasmasphere extends beyond L~ 5 favor long‐lasting hiss losses from the outer belt. Such loss rates are embedded in a reduced Fokker‐Planck code and validated against Magnetic Electron and Ion Spectrometer observations of the belts at all energy. Results are complemented with a sensitivity study involving different radial diffusion and lifetime models. Validation is carried out globally at all Lshells and energies. The good agreement between simulations and observations demonstrates that hiss waves drive the slot formation during quiet times. Combined with transport, they sculpt the energy structure of the outer belt into an “S shape.” Low energy electrons (<0.3 MeV) are less subject to hiss scattering below L= 4. In contrast, 0.3–1.5 MeV electrons evolve in an environment that depopulates them as they migrate from L~ 5 to L~ 2.5. Ultrarelativistic electrons are not affected by hiss losses until L~ 2–3. Computations of daily pitch angle diffusion coefficients and electron lifetimes from properties of hiss waves observed in March 2013Good agreement found between MagEIS flux observations and 1‐D Fokker‐Planck simulations based on our hiss loss term for quiet timesCombined with transport, hiss waves loss drives the daily energy structure of the radiation belts, with a typical S‐shaped outer belt

A new empirical density model is developed for the inner zone between 1 < L< 3 using plasma densities inferred from the upper hybrid resonance on Arase, and hiss‐inferred density values from Van Allen Probes. The Van Allen Probes hiss‐inferred densities are first recalibrated and validated against Arase observations, using both a conjunction event and statistical analyses. The newly developed density model includes dependencies on L, magnetic latitude, and magnetic local time (MLT). Between 1.5 < L< 3.0, the equatorial density variation with Lis shown to be equivalent to that of the Ozhogin et al. (2012, https://doi.org/10.1029/2011JA017330) model. However, for L< 1.5, this dependence changes as the plasma density increases at a faster rate with decreasing L. The latitudinal dependence of the plasma density is shown to present a flatter profile than previous models, meaning lower densities extend to higher latitudes. This dependence is well‐modeled by updated fitting coefficients. A clear MLT dependence of the plasma density is identified, which was not found or included in some previous models. This variation is consistent with the diurnal variation of the ionosphere, peaking near MLT = 14 and becoming larger in amplitude with decreasing L. A function describing this MLT dependence is presented. Overall, the new L, latitude, and MLT‐dependent empirical model can provide density values in areas outside the validity region of many previous models, making it a useful resource for accurately determining diffusion coefficients and predicting electron dynamics and their lifetimes in the inner radiation belt. Radiation Belt Storm Probes and Arase data are used to build a new empirical plasma density model for the inner zone, including L, latitude, and magnetic local time (MLT) dependenciesMLT dependence consistent with diurnal variation of ionosphere. Variation is largest in amplitude at low L, but persists out to L= 3New model provides density in areas outside previous model bounds, making it a useful resource for modeling inner radiation belt dynamics Radiation Belt Storm Probes and Arase data are used to build a new empirical plasma density model for the inner zone, including L, latitude, and magnetic local time (MLT) dependencies MLT dependence consistent with diurnal variation of ionosphere. Variation is largest in amplitude at low L, but persists out to L= 3 New model provides density in areas outside previous model bounds, making it a useful resource for modeling inner radiation belt dynamics

These lecture notes present an introduction to the strongly correlated regime of low dimensional atomic gases. The discussion is concentrated on situations in which the strongly correlated limit is achieved by creating degeneracies in the one-particle motional states. Three different schemes of experimental relevance are analyzed: bosonic atoms in a two dimensional rapidly rotating trap, bosonic atoms in a one dimensional optical lattice, and bosonic atoms with frozen motional degrees of freedom and two internal states. The corresponding entangled multiparticle states (Laughlin liquids, Mott phases, squeezed states), and the different strongly correlated phenomena that appear (fermionization, fractional statistics) are studied. Emphasis is given to the possibility of observing novel strongly correlated phenomena as well as to the possible implementations for quantum computation and quantum information.

The study of light–matter interaction has led to important advances in quantum optics and enabled numerous technologies. Over recent decades, progress has been made in increasing the strength of this interaction at the single-photon level. More recently, a major achievement has been the demonstration of the so-called strong coupling regime, a key advancement enabling progress in quantum information science. Here, we demonstrate light–matter interaction over an order of magnitude stronger than previously reported, reaching the nonperturbative regime of ultrastrong coupling (USC). We achieve this using a superconducting artificial atom tunably coupled to the electromagnetic continuum of a one-dimensional waveguide. For the largest coupling, the spontaneous emission rate of the atom exceeds its transition frequency. In this USC regime, the description of atom and light as distinct entities breaks down, and a new description in terms of hybrid states is required. Beyond light–matter interaction itself, the tunability of our system makes it a promising tool to study a number of important physical systems, such as the well-known spin-boson and Kondo models.

In this study, we complement the notion of equilibrium states of the radiation belts with a discussion on the dynamics and time needed to reach equilibrium. We solve for the equilibrium states obtained using 1‐D radial diffusion with recently developed hiss and chorus lifetimes at constant values of Kp= 1, 3, and 6. We find that the equilibrium states at moderately low Kp, when plotted versus L shell (L) and energy (E), display the same interesting S shape for the inner edge of the outer belt as recently observed by the Van Allen Probes. The S shape is also produced as the radiation belts dynamically evolve toward the equilibrium state when initialized to simulate the buildup after a massive dropout or to simulate loss due to outward diffusion from a saturated state. Physically, this shape, intimately linked with the slot structure, is due to the dependence of electron loss rate (originating from wave‐particle interactions) on both energy and L shell. Equilibrium electron flux profiles are governed by the Biot number (τDiffusion/τloss), with large Biot number corresponding to low fluxes and low Biot number to large fluxes. The time it takes for the flux at a specific (L, E) to reach the value associated with the equilibrium state, starting from these different initial states, is governed by the initial state of the belts, the property of the dynamics (diffusion coefficients), and the size of the domain of computation. Its structure shows a rather complex scissorform in the (L, E) plane. The equilibrium value (phase space density or flux) is practically reachable only for selected regions in (L, E) and geomagnetic activity. Convergence to equilibrium requires hundreds of days in the inner belt for E> 300 keV and moderate Kp(≤3). It takes less time to reach equilibrium during disturbed geomagnetic conditions (Kp≥ 3), when the system evolves faster. Restricting our interest to the slot region, below L = 4, we find that only small regions in (L, E) space can reach the equilibrium value: E~ [200, 300] keV for L = [3.7, 4] at Kp= 1, E~[0.6, 1] MeV for L = [3, 4] at Kp= 3, and E~300 keV for L = [3.5, 4] at Kp= 6 assuming no new incoming electrons. The time to reach equilibrium value has a complex scissor shape in (L, E)Equilibrium value only reachable for selected and determined (L, E, Kp)Dynamics and equilibrium S shape of the belts as in VAP observations

Multispectral tissue imaging based on optical cameras and continuous-wave tissue illumination is commonly used in medicine and biology. Surprisingly, there is a characteristic absence of a critical look at the quantities that can be uniquely characterized from optically diffuse matter by multispectral imaging. Here, we investigate the fundamental question of uniqueness in epi-illumination measurements from turbid media obtained at multiple wavelengths. By utilizing an analytical model, tissue-mimicking phantoms, and an in vivo imaging experiment we show that independent of the bands employed, spectral measurements cannot uniquely retrieve absorption and scattering coefficients. We also establish that it is, nevertheless, possible to uniquely quantify oxygen saturation and the Mie scattering power—a previously undocumented uniqueness condition.

We present dynamic simulations of energy-dependent losses in the radiation belt “slot region” and the formation of the two-belt structure for the quiet days after the 1 March storm. The simulations combine radial diffusion with a realistic scattering model, based data-driven spatially and temporally resolved whistler-mode hiss wave observations from the Van Allen Probes satellites. The simulations reproduce Van Allen Probes observations for all energies and L shells (2–6) including (a) the strong energy dependence to the radiation belt dynamics (b) an energy-dependent outer boundary to the inner zone that extends to higher L shells at lower energies and (c) an “S-shaped” energy-dependent inner boundary to the outer zone that results from the competition between diffusive radial transport and losses. We find that the characteristic energy-dependent structure of the radiation belts and slot region is dynamic and can be formed gradually in ~15?days, although the “S shape” can also be reproduced by assuming equilibrium conditions. The highest-energy electrons (E?>?300?keV) of the inner region of the outer belt (L?~?4–5) also constantly decay, demonstrating that hiss wave scattering affects the outer belt during times of extended plasmasphere. Through these simulations, we explain the full structure in energy and L shell of the belts and the slot formation by hiss scattering during storm recovery. We show the power and complexity of looking dynamically at the effects over all energies and L shells and the need for using data-driven and event-specific conditions. Simulations use radial diffusion coupled with a data-driven hiss scattering modelHiss scattering locations correspond to the observed slot evolution in March 2013Numerical recovery of the energy-dependent structure of the belts and the slot formation

We deduce the electron plasma density from the NASA Van Allen Probes Electric Field and Waves and Electric and Magnetic Field Instrument Suite and Integrated Science measurements and extract the plasmasphere boundaries throughout 2012–2019. We use the gradient method for locating the plasmapause at Lppand the 100 cm−3density threshold for the plasmasphere outer edge at L100. We show how, where, and when both Lppand L100coincide when the plasmapause gradient exists. L100is demonstrated to bound the plasmasphere at large L‐shell in the dusk. The plasmasphere expands farther out than predicted from the Carpenter and Anderson (1992, https://doi.org/10.1029/91JA01548) model. We generate statistics of the plasmasphere boundaries binned by L‐shell, magnetic local time (MLT), and geomagnetic indices, leading to new models for radiation belt codes. The L100boundary commonly varies by ∼±0.5 L, increasing with activity up to ∼±1 L, becomes MLT‐dependent for Kp > ∼2, and is preferentially steep on the night side for non‐quiet times and a wider region in the afternoon sector. The plasmasphere is a region of plasma extending out from the ionized upper part of the atmosphere to distances of 2–6 Earth Radii. The plasmasphere plasma is the coldest plasma (1/100–1/1,000,000 of the energy of other plasma) in the space around Earth where the particle motions are regulated by Earth's magnetic field (the magnetosphere). It is also high density, 100–10,000 times higher than elsewhere in the magnetosphere. The outer edge of the plasmasphere, called the plasmapause, typically drops from >100 to <10 cm−3over a relatively short distance. Waves that energize radiation belt particles (chorus) are found outside the plasmasphere. Inside the plasmasphere are different waves (hiss) that cause radiation belt particles to precipitate into Earth's atmosphere. Therefore, models predicting the radiation belt's behavior need to know the plasmapause location. To predict the plasmapause position, we analyze 7 years of Van Allen Probes data to find the plasma density in two different ways, using both the 100 cm−3density and the density gradient. We look at how their locations change with the level of geomagnetic storm activity and deduce new plasmasphere boundaries models for space weather codes. We deduce the electron plasma density from Electric Field and Waves and Electric and Magnetic Field Instrument Suite and Integrated Science measurements (2012–2019) and extract the plasmasphere boundariesNew plasmasphere boundary statistics and laws, binned by L, magnetic local time, and geomagnetic indices are generated to be used in space weather codesA density‐based boundary is more frequently defined than is a gradient‐based boundary, and yields a more frequently applicable model We deduce the electron plasma density from Electric Field and Waves and Electric and Magnetic Field Instrument Suite and Integrated Science measurements (2012–2019) and extract the plasmasphere boundaries New plasmasphere boundary statistics and laws, binned by L, magnetic local time, and geomagnetic indices are generated to be used in space weather codes A density‐based boundary is more frequently defined than is a gradient‐based boundary, and yields a more frequently applicable model

We describe a family of lattice models that support a new class of quantum magnetism characterized by correlated spin and bosonic ordering [Phys. Rev. Lett. 112, 180405 (2014)]. We explore the full phase diagram of the model using Matrix-Product-State methods. Guided by these numerical results, we describe a modified variational ansatz to improve our analytic description of the groundstate at low boson frequencies. Additionally, we introduce an experimental protocol capable of inferring the low-energy excitations of the system by means of Fano scattering spectroscopy. Finally, we discuss the implementation and characterization of this model with current circuit-QED technology.

Abstract: We describe the dynamics of a qubit interacting with a bosonic mode coupled to a zero-temperature bath in the deep strong coupling (DSC) regime. We provide an analytical solution for this open system dynamics in the off-resonance case of the qubit-mode interaction. Collapses and revivals of parity chain populations and the oscillatory behavior of the mean photon number are predicted. At the same time, photon number wave packets, propagating back and forth along parity chains, become incoherently mixed. Finally, we investigate numerically the effect of detuning on the validity of the analytical solution.

Proponer la utilización de un glucómetro digital como método cuantitativo sencillo para detectar líquido cefalorraquídeo durante la técnica de anestesia combinada epidural-intradural y determinar su validez, a través de la sensibilidad, especificidad, valores predictivos y cocientes de probabilidad

Determinar la capacidad del índice biespec-tral (BIS) como predictor de amnesia anterógrada para los eventos que ocurren desde la llegada a quirófano de los pacientes hasta la inducción anestésica, después de preme-dicarlos con 10mg de midazolam intranasal.

One of the main goals in optical characterization of biopsies is to discern between tissue types. Usually, the theory used for deriving the optical properties of such highly scattering media is based on the diffusion approximation. However, biopsies are usually small in size compared to the transport mean free path and thus cannot be treated with standard diffusion theory. To account for this, an improved theory was developed, by the authors, that can correctly describe light propagation in small geometries (Garofalakis et al 2004 J. Opt. A: Pure Appl. Opt. 6 725–35). The theory's limit was validated by both Monte Carlo simulations and experiments performed on tissue-like phantoms, and was found to be two transport mean free paths. With the aid of this theory, we have characterized 59 samples of breast tissue including cancerous samples by retrieving their reduced scattering coefficients from time-resolved transmission data. The mean values for the reduced scattering coefficients of the normal and the tumour tissue were measured to be 9.7 ± 2.2 cm⁻¹ and 10.8 ± 1.8 cm⁻¹, respectively. The correlation with age was also investigated.

This paper summarizes some important achievements of quantum information processing with trapped ions or neutral atoms. In particular, we describe the storage of information and realization of two-qubit gates with ions, as well as the creation of entanglement and quantum simulation with cold atoms in optical lattices.

This paper summarizes some important achievements of quantum information processing with trapped ions or neutral atoms. In particular, we describe the storage of information and realization of two-qubit gates with ions, as well as the creation of entanglement and quantum simulation with cold atoms in optical lattices.

Given an orientable hypersurface M of a Lie group ?? with a bi-invariant metric we consider the map N : M ? ?? n that translates the normal vector field of M to the identity, which is a natural extension of the usual Gauss map of hypersurfaces in Euclidean spaces; it is proved that the Laplacian of N satisfies a formula similar to that satisfied by the usual Gauss map. One may then conclude that M has constant mean curvature (cmc) if and only if N is harmonic; some other aplications to cmc hypersurfaces of ?? are also obtained.

A simple one-dimensional model of a pool fire (diffusion flame) is derived from the three-dimensional (or two-dimensional) equations of a reacting flow assuming the fire profile. Assumptions about the fresh air entering the column by free convection and about the fuel vaporization are used in order to close the system. This model has been implemented and a numerical study is provided.

We define and compute mean absorption coefficients for the macroscopic models of radiative transfer. These coefficients take into account the anisotropic form of the photon emission and lead to a better computation of a photonic flow far from the radiative equilibrium. They are deduced by averaging a specific radiative intensity on the space of frequency and are generalized versions of the Planck means. This intensity is obtained by minimizing the mathematical entropy with the constraint of the reconstruction of radiative moments and constitutes the closure of the M1 radiative model. We discuss the influence of these coefficients, extend them to the case of multi-frequency problems and perform a numerical comparison with the former Planck mean.

By means of a surface-integral formalism we derive the integral equations for diffuse photon density waves with boundary conditions corresponding to a diffusediffuse interface with index mismatch and solve them numerically without any approximation. These numerical results are verified with Monte Carlo simulations for the planar interface case. Since the application of the boundary condition to index-mismatched media is difficult, an approximation that yields very accurate values is found. This approximation can be easily introduced into analytical models, and a study of its limit of validity is shown. We demonstrate with numerical results that the multiple-scattering contribution that is due to surface roughness can be neglected, even when index mismatch is present. S0740-3232(99)01308-3

On comparison with the usual propagating scalar waves, the attenuation of diffuse photon density waves gives rise to important differences in structural information, such as higher spatial resolution in detection at short distances from objects and deviation from the Rayleigh limit at larger distances. This damping also establishes a minimum spatial resolution threshold for diffusive waves, which occurs by illumination in continuous mode, and demonstrates that in most cases spatial resolution is not improved by increasing the modulation frequency. Assessments of this formulation with numerical simulations of scattering and wave-front reconstruction in the presence of noise are given.

The surface integral formalism is used to derive the integral equations for the scattering of diffusive waves, which account for the contribution of object boundaries and interfaces between media and which are numerically solved without approximations. The extinction theorem and other surface integral theorems for diffusive waves are introduced to obtain the boundary values of both the photon density wave and the photon density current. We present this theory and apply it to the simulation of diffusive objects buried in diffusive media in the presence of rough interfaces.

By means of a surface-integral formalism we derive the integral equations for diffuse photon density waves with boundary conditions corresponding to a diffuse–diffuse interface with index mismatch and solve them numerically without any approximation. These numerical results are verified with Monte Carlo simulations for the planar interface case. Since the application of the boundary condition to index-mismatched media is difficult, an approximation that yields very accurate values is found. This approximation can be easily introduced into analytical models, and a study of its limit of validity is shown. We demonstrate with numerical results that the multiple-scattering contribution that is due to surface roughness can be neglected, even when index mismatch is present.

The flash vacuum thermolysis of propargylthio- and allylthiodialkylsilanes, potential precursors of unhindered silanethiones (R2Si&dbd;S), has been investigated by photoelectron spectroscopy. This technique allowed us to characterize in the gas phase two very reactive species of this series, dimethyl- and diisopropylsilanethione. According to the values observed for the ionization potentials associated with the ejection of a π electron, the πSi&dbd;S double bond is energetically more stable than the earlier studied Si&dbd;N double bond.

The unhindered 1,1-dimethylyl-N-dimethylsilylsilanimine was generated by the retroene reaction of the N-propargyl-1,1,3,3-tetramethyldisilazane under flash vacuum thermolysis conditions. This reactive silanimine was characterized for the first time by its photoelectron spectrum. The ionization potentials associated with the ejection of an electron from the nN and πSi = N orbitals are observed at 8.3 and 9.0 eV, respectively. This experimental result has been confirmed by an ab initio theoretical investigation of the Si = N-Si backbone using 6-31 G (d) and LANLIDZ basis set and MP2 level: electronic and structural characteristics of (CH3)2Si = N-SiH(CH3)2 have been thus determined.

The flash vacuum thermolysis of cyclodisilaphosphanes, cyclotrisilaphosphanes, and a phosphasilacyclobutane, potential precursors of unhindered silylidenephosphanes (R2Si&dbd;PR‘), has been investigated by NMR as well as by coupling with HRMS and, particularly, photoelectron spectroscopy. This last technique led us to characterize for the first time, in the gas phase, two very reactive species of this series, the P-tert-butyl- and P-phenyl(dimethylsilylidene)phosphanes (Me2Si&dbd;P-t-Bu and Me2Si&dbd;PPh). The first ionization potentials at weaker energy are associated with the ejection of an electron from the πSi&dbd;P bond. The ionizations of the lone pair on phosphorus are observed at higher energy.

A method for the extraction of ctDNA from isolated chloroplast was developed. This method is simple and adapted particularly to broad-leaved trees, including sclerophyllous species with high phenolic and polysaccharide contents. This method includes two major steps: first, chloroplasts are isolated in non-aqueous solutions to avoid oxidation and phenolic problems; second, ctDNA is extracted from the chloroplasts using aqueous solutions and specific methods to provide highly purified ctDNA.

Electron flux variations for E> 500 keV during geomagnetic storms are investigated using the Energetic Particle Telescope (EPT). This detector launched in May 2013 on board the satellite PROBA‐V at an altitude of 820 km was designed to provide uncontaminated spectra of electrons, protons, and alpha particles. Electron flux dropout events are observed during the main phase of each storm and even during substorms: a rapid reduction of the electron flux is noted throughout the outer electron radiation belt at all energies above about 0.5 MeV on timescales of a few hours. The electron spectrograms measured by the EPT between 2013 and 2019 show that after each geomagnetic storm, dropout events are followed by a flux enhancement starting first at low Lvalues, and reaching the slot or even the inner belt for the strongest storms. We determine the link between Disturbed Storm Time (Dst) and the minimum value of the L‐shell where the dropouts deplete the outer belt, as well as the nonlinear relation between Dst and the minimum L‐shell where the flux penetrates in the slot region or even the inner belt during the storms. Dropouts appear at all energies measured by EPT and penetrate down to L∼3.5 for the strongest events. Dropouts are observed at Low Earth Orbit each time Dst has an inverted peak < −40 nT. Flux enhancements appear at lower L only for big storm events with Dst < −50 nT. They penetrate down to an impenetrable barrier with a minimum L‐shell related to Dst and to the energy. For E> 1 MeV, this limit is also linked to the plasmapause position. Electron >500 keV flux measured by Energetic Particle Telescope at Low Earth Orbit from 2013 to 2019 shows dropouts followed by enhancements during all geomagnetic stormsThe study shows that dropouts deplete the outer radiation belt down to a minimum L‐shell related to disturbed storm time (Dst)Electron fluxes are enhanced in the slot down to an impenetrable barrier with a L‐shell related to Dst and to the plasmapause position Electron >500 keV flux measured by Energetic Particle Telescope at Low Earth Orbit from 2013 to 2019 shows dropouts followed by enhancements during all geomagnetic storms The study shows that dropouts deplete the outer radiation belt down to a minimum L‐shell related to disturbed storm time (Dst) Electron fluxes are enhanced in the slot down to an impenetrable barrier with a L‐shell related to Dst and to the plasmapause position

The very low‐frequency transmitter in the Northwest Cape of Australia (NWC) has previously been observed to pitch‐angle scatter electrons with energies from 30–400 keV, creating enhanced fluxes measured by low‐Earth orbiting (LEO) satellites. Here we use observations from the Energetic Particle Telescope on PROBA‐V. We compare the measured flux, as a function of local magnetic field strength, when the NWC transmitter is “on” versus “off,” and find enhanced fluxes only when NWC is “on” and located on the nightside. The enhanced fluxes occur in the population gradually transitioning from “permanently trapped” to “quasi‐trapped.” We show that electrons up to 800 keV, substantially higher energy than previously studied, are scattered by resonant interactions with NWC to produce enhanced fluxes. The enhanced fluxes appear at multiple L‐shells for each energy channel, consistent with resonance conditions at distinct wave normal angles, that indicate ducted interactions at L < 1.55 and unducted interactions at L > 1.65. Radio waves with a low enough frequency can reflect off Earth's surface as well as the ionosphere, a layer of charged particles above Earth's atmosphere created by the Sun's ionization of the upper atmosphere. These waves bounce back and forth in the Earth‐ionosphere waveguide, enabling AM (Amplitude Modulation) radio to be heard at large distances, for example. Transmitters with even lower frequencies than AM radio, in the tens of kiloHertz range, are used to communicate with submarines just below the ocean's surface that can be located on the other side of the world. The ionosphere is not a perfect reflector, though, and some of the transmitter wave power escapes into Earth's magnetosphere, a region where charged particles like electrons can be trapped for many months on magnetic field lines. The radio waves can scatter the trapped electrons into Earth's atmosphere, where they rapidly lose energy and no longer pose a threat to space‐based assets. Understanding how naval transmitters scatter trapped electrons is needed to help us explain why electrons stay trapped for as long as they do, and enable us to predict radiation damage to the growing number of satellites that orbit Earth with low altitudes, which limits the satellite's useful lifetime. The ground‐based transmitter in northwest Australia scatters electrons into the drift loss coneThe Energetic Particle Telescope on the PROBA‐V satellite sees enhanced fluxes at 500–800 keV from low‐Earth orbitThe enhanced fluxes occur at energy‐dependent L‐shells that are consistent with the resonance condition for ducted and nonducted waves

The past decade transformed our observational understanding of energetic particle processes in near‐Earth space. An unprecedented suite of observational systems was in operation including the Van Allen Probes, Arase, Magnetospheric Multiscale, Time History of Events and Macroscale Interactions during Substorms, Cluster, GPS, GOES, and Los Alamos National Laboratory‐GEO magnetospheric missions. They were supported by conjugate low‐altitude measurements on spacecraft, balloons, and ground‐based arrays. Together, these significantly improved our ability to determine and quantify the mechanisms that control the buildup and subsequent variability of energetic particle intensities in the inner magnetosphere. The high‐quality data from National Aeronautics and Space Administration's Van Allen Probes are the most comprehensive in situ measurements ever taken in the near‐Earth space radiation environment. These observations, coupled with recent advances in radiation belt theory and modeling, including dramatic increases in computational power, have ushered in a new era, perhaps a “golden era,” in radiation belt research. We have edited a Journal of Geophysical Research: Space Science Special Collection dedicated to Particle Dynamics in the Earth's Radiation Belts in which we gather the most recent scientific findings and understanding of this important region of geospace. This collection includes the results presented at the American Geophysical Union Chapman International Conference in Cascais, Portugal (March 2018) and many other recent and relevant contributions. The present article introduces and review the context, current research, and main questions that motivate modern radiation belt research divided into the following topics: (1) particle acceleration and transport, (2) particle loss, (3) the role of nonlinear processes, (4) new radiation belt modeling capabilities and the quantification of model uncertainties, and (5) laboratory plasma experiments. We review and discuss current research and open questions relative to Earth's radiation beltsAspects of modern radiation belt research concern particle acceleration and transport, particle loss, and the role of nonlinear processesWe also discuss new radiation belt modeling capabilities, the quantification of model uncertainties, and laboratory plasma experiments

We provide a statistical analysis of both electric and magnetic field wave amplitudes of very low frequency lightning‐generated waves (LGWs) based on the equivalent of 11.5 years of observations made by the Van Allen Probes encompassing ~24.6 × 106survey mode measurements. We complement this analysis with data from the ground‐based World Wide Lightning Location Network to explore differences between satellite and ground‐based measurements. LGW mean amplitudes are found to be low compared with other whistler mode waves (1 ± 1.6 pT and 19 ± 59 μV/m). Extreme events (1/5,000) can reach 100 pT and contributes strongly to the mean power below L= 2. We find excellent correlations between World Wide Lightning Location Network‐based power and wave amplitudes in space at various longitudes. We reveal strong dayside ionospheric damping of the LGW electric field. LGW amplitudes drop for L< 2, contrary to the Earth's intense equatorial lightning activity. We conclude that it is difficult for equatorial LGW to propagate and remain at L< 2. Lightning flashes emit powerful electromagnetic lightning‐generated waves (LGWs). Some of this power propagates and escapes into the magnetosphere. Resonant interactions of trapped electrons in the Van Allen belts with LGWs cause pitch angle diffusion, leading to scattering of those electrons into the atmosphere, an important process for estimating the radiation levels encountered by satellites in low Earth orbits. Here, we analyze the electric and magnetic field wave amplitudes of LGWs measured by the two National Aeronautics and Space Administration Van Allen Probes during their entire mission. We compare these spacecraft observations with an estimate for the very low frequency (VLF) wave power escaping to space using the ground‐based World Wide Lightning Location Network to measure lightning VLF radiation on Earth. We discuss the main features of the LGW amplitude distributions with respect to position relative to the Sun (local time), magnetic field lines (L‐shell, L), longitude, and time (month or season). Monthly and yearly statistics of electric and magnetic LGW amplitudes are generated and reveal an important decay below L= 2 indicating that LGW VLF power is not efficiently transmitted into space on Earth's lowest latitude magnetic field lines, particularly during the day. We analyze electric and magnetic lightning‐generated wave (LGW) amplitudes from ~11 years of Van Allen Probes dataLGW amplitudes correlate well in longitude with a WWLLN proxy (L< 2); we find strong dayside ionospheric damping of the LGW electric powerMean electric and magnetic lightning‐generated wave amplitudes decay below L= 2, opposite to intense lightning equatorial activity

Diffuse photon density waves are proposed for use in characterizing diffuse media, similar to the use of electro-magnetic waves to characterize reflection from materials. To this end basic expressions for the reflection and transmission coefficients at interfaces are put forward. Effects such as the existence of modes analogous with Brewster modes are shown. Also, we illustrate through numerical simulations how the diffusion optical parameters are estimated both with and without noise in the data.