Classical Radiation Reaction in Particle-In-Cell Simulations

Under the presence of ultra high intensity lasers or other intense electromagnetic fields the motion of particles in the ultrarelativistic regime can be severely affected by radiation reaction. The standard particle-in-cell (PIC) algorithms do not include radiation reaction effects. Even though this is a well known mechanism, there is not yet a definite algorithm nor a standard technique to include radiation reaction in PIC codes. We have compared several models for the calculation of the radiation reaction force, with the goal of implementing an algorithm for classical radiation reaction in the Osiris framework, a state-of-the-art PIC code. The results of the different models are compared with standard analytical results, and the relevance/advantages of each model are discussed. Numerical issues relevant to PIC codes such as resolution requirements, application of radiation reaction to macro particles and computational cost are also addressed. The Landau and Lifshitz reduced model is chosen for implementation.Comment: 12 pages, 8 figure

Full-scale ab initio 3D PIC simulations of an all-optical radiation reaction configuration at 1021W/cm210^{21}\mathrm{W/cm^2}

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 $\sim$1 GeV laser wakefield accelerated (LWFA) electron bunch with a counter propagating laser pulse. In this configuration 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 classical and quantum radiation reaction could be investigated in the same configuration with laser intensities of $10^{24}\mathrm{W/cm^2}$

Particle Merging Algorithm for PIC Codes

Particle-in-cell merging algorithms aim to resample dynamically the six-dimensional phase space occupied by particles without distorting substantially the physical description of the system. Whereas various approaches have been proposed in previous works, none of them seemed to be able to conserve fully charge, momentum, energy and their associated distributions. We describe here an alternative algorithm based on the coalescence of N massive or massless particles, considered to be close enough in phase space, into two new macro-particles. The local conservation of charge, momentum and energy are ensured by the resolution of a system of scalar equations. Various simulation comparisons have been carried out with and without the merging algorithm, from classical plasma physics problems to extreme scenarios where quantum electrodynamics is taken into account, showing in addition to the conservation of local quantities, the good reproducibility of the particle distributions. In case where the number of particles ought to increase exponentially in the simulation box, the dynamical merging permits a considerable speedup, and significant memory savings that otherwise would make the simulations impossible to perform

Cluster magnetic fields from large-scale-structure and galaxy-cluster shocks

The origin of the micro-Gauss magnetic fields in galaxy clusters is one of the outstanding problem of modern cosmology. We have performed three-dimensional particle-in-cell simulations of the nonrelativistic Weibel instability in an electron-proton plasma, in conditions typical of cosmological shocks. These simulations indicate that cluster fields could have been produced by shocks propagating through the intergalactic medium during the formation of large-scale structure or by shocks within the cluster. The strengths of the shock-generated fields range from tens of nano-Gauss in the intercluster medium to a few micro-Gauss inside galaxy clusters.Comment: 4 pages, 2 color figure

Application of SPS in the fabrication of UN and (U,Th)N pellets from microspheres

In this study, the process involved in the fabrication of a potential accident tolerant fuel is described. Homogeneous uranium nitride microspheres doped with different thorium content were successfully manufactured using an internal gelation process followed by carbothermic reduction, and nitridation. Elemental analysis of the materials showed low carbon and oxygen content, the two major impurities found in the products of carbothermic reduction. Uranium nitride microspheres were pressed and sintered using spark plasma sintering (SPS) to produce pellets with variable density. Final density can be tailored by choosing the sintering temperature, pressure and time. Density values of 77–98% of theoretical density (%TD) were found. As expected, higher temperatures and pressures resulted in a denser material. Furthermore, a direct correlation between the onset sintering temperature and thorium content in the materials was observed. The change of onset temperature has been related to an increment in the activation energy for self-diffusion due to the substitution of uranium atoms by thorium in the crystal structure

Maternal Low-Protein Diet Deregulates DNA Repair and DNA Replication Pathways in Female Offspring Mammary Gland Leading to Increased Chemically Induced Rat Carcinogenesis in Adulthood

Studies have shown that maternal malnutrition, especially a low-protein diet (LPD), plays a key role in the developmental mechanisms underlying mammary cancer programming in female offspring. However, the molecular pathways associated with this higher susceptibility are still poorly understood. Thus, this study investigated the adverse effects of gestational and lactational low protein intake on gene expression of key pathways involved in mammary tumor initiation after a single dose of N-methyl-N-nitrosourea (MNU) in female offspring rats. Pregnant Sprague–Dawley rats were fed a normal-protein diet (NPD) (17% protein) or LPD (6% protein) from gestational day 1 to postnatal day (PND) 21. After weaning (PND 21), female offspring (n = 5, each diet) were euthanized for histological analysis or received NPD (n = 56 each diet). At PND 28 or 35, female offspring received a single dose of MNU (25 mg/kg body weight) (n = 28 each diet/timepoint). After 24 h, some females (n = 10 each diet/timepoint) were euthanized for histological, immunohistochemical, and molecular analyses at PDN 29 or 36. The remaining animals (n = 18 each diet/timepoint) were euthanized when tumors reached ≥2 cm or at PND 250. Besides the mammary gland development delay observed in LPD 21 and 28 groups, the gene expression profile demonstrated that maternal LPD deregulated 21 genes related to DNA repair and DNA replication pathways in the mammary gland of LPD 35 group after MNU. We further confirmed an increased γ-H2AX (DNA damage biomarker) and in ER-α immunoreactivity in mammary epithelial cells in the LPD group at PND 36. Furthermore, these early postnatal events were followed by significantly higher mammary carcinogenesis susceptibility in offspring at adulthood. Thus, the results indicate that maternal LPD influenced the programming of chemically induced mammary carcinogenesis in female offspring through increase in DNA damage and deregulation of DNA repair and DNA replication pathways. Also, Cidea upregulation gene in the LPD 35 group may suggest that maternal LPD could deregulate genes possibly leading to increased risk of mammary cancer development and/or poor prognosis. These findings increase the body of evidence of early-transcriptional mammary gland changes influenced by maternal LPD, resulting in differential response to breast tumor initiation and susceptibility and may raise discussions about lifelong prevention of breast cancer risk.Fil: Zapaterini, Joyce R.. Universidade Estadual Paulista Julio de Mesquita Filho; BrasilFil: Fonseca, Antonio R. B.. Universidade Estadual Paulista Julio de Mesquita Filho; BrasilFil: Bidinotto, Lucas T.. Barretos Cancer Hospital; Brasil. Barretos School of Health Sciences; BrasilFil: Colombelli, Ketlin T.. Universidade Estadual Paulista Julio de Mesquita Filho; BrasilFil: Rossi, André L. D.. Universidade Estadual Paulista Julio de Mesquita Filho; BrasilFil: Kass, Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Salud y Ambiente del Litoral. Universidad Nacional del Litoral. Instituto de Salud y Ambiente del Litoral; ArgentinaFil: Justulin, Luis A.. Universidade Estadual Paulista Julio de Mesquita Filho; BrasilFil: Barbisan, Luis F.. Universidade Estadual Paulista Julio de Mesquita Filho; Brasi

Procedimiento para el secado al sol de un alimento para animales (GARANVER) a partir de residuos industriales de la caña de azúcar

A study to establish drying parameters for a kind of animal food  (GARANVER) was carried on. GARANVER is made of sugar cane industrial wastes, i. e., a mixture of pressed sugar cane pith, liquid wastes (acid, alkaline, and sugary residuals), urea, and final molasses. The animal food was exposed to sun rays on a concrete floor for three days. Treatments applied were four dif- ferent GARANVER densities (70; 85; 100 and 125 ton/ha) and two different turning-over frequencies (every one and two hours) with five replicas. Data were evaluated by a simple classification variance analysis with a factorial arrangement. Variation of dry matter at 24; 48 and 72 h was taken as measurable parameter. Dried GARANVER was stocked for six months and its broma- tological components behavior was monthly checked. Results showed a possibility to reach DM levels above 85% with densities of 70 and 125 ton/ha at 48 and 72 hours and a turning-over frequency every one and two hours, respectively. Cost per unit is 35,16 and 34,28 Cuban pesos. GARANVER nutrient components remained stable while stocked.Se hizo un estudio para establecer los parámetros de secado de un alimento para animales denominado GARANVER, elaborado a partir de residuos industriales de la caña de azúcar; es una mezcla de bagacillo, residuales líquidos (ácidos, alcalinos y azucara- dos), urea y miel final. El alimento se expuso al sol durante tres días, sobre una superficie pavimentada. Los tratamientos utiliza- dos fueron cuatro densidades (70; 85; 100 y 125 t/ha) y dos frecuencias de volteo (una vuelta por 1 h y una cada 2 h) replicados cinco veces. Como parámetro medible se tomó la variación de materia seca (MS) a las 24; 48 y 72 h. Los datos fueron evaluados en un análisis de varianza de clasificación simple con arreglo factorial. El material seco se almacenó durante seis meses y se con- troló mensualmente el comportamiento de los componentes bromatológicos. Los resultados muestran la posibilidad de alcanzar niveles de MS por encima del 85 % con densidades de 70 y de 125 t/ha a las 48 y 72 horas con una frecuencia de volteo cada 1 y cada 2 h respectivamente y un costo unitario de 35,16 y 34,28 pesos cubanos. Los componentes nutritivos se mantuvieron estables durante el periodo de almacenamiento

Entangled-State Lithography: Tailoring any Pattern with a Single State

We demonstrate a systematic approach to Heisenberg-limited lithographic image formation using four-mode reciprocal binominal states. By controlling the exposure pattern with a simple bank of birefringent plates, any pixel pattern on a $(N+1) \times (N+1)$ grid, occupying a square with the side half a wavelength long, can be generated from a $2 N$-photon state.Comment: 4 pages, 4 figure

Secado y conservación durante el almacenamiento de un alimento para animales elaborado con cachaza, bagacillo y residuales líquidos (GARANVER)

A preliminary study  on  a  small scale to establish the  drying parameters for an  animal feedstuff (GARANVER) containing filter cake  mud, sugarcane bagasse pith, liquid waste (acid,  alkaline, and  sugared residuals), urea, and  final molasses was carried out.  The feedstuff was exposed to sun rays on  a  concrete floor. Treatments applied were  four feedstuff densities (70, 85, 100,  and  125 t/ha),  and  two turnover  frequencies (every  one and  two hours). Each  treatment had  five replicas. Raw  matter  variation was taken  as a measuring parameter at  24,  48,  and  72  hours.   Data  were  evaluated according to  a simple  classification  variance  analysis  with  a  factorial  arrangement. Afterwards,  drying was performed on a commercial scale with two feedstuff densities (70 and  125 t/ha). Dry matter  was sampled for microbiological tests. The feedstuff was storaged for six months and  its bromatological components were  monthly tested. Results showed the possibility of reaching a dry matter  level above 85 % with a 70 t/ha density  at 48 hours and  an hour turnover  frequency. With feedstuff densities of 80; 100,  and  125  t/ha,  the  period of time enlarged  up   to   72   hours  with  both   turnover   frequencies.  Feedstuff  drying  on   a commercial scale showed a similar behaviour. The microbiological tests showed neither Salmonella nor other proteolytic organisms. Nutrient components remained stable during the storage period.Se  hizo primeramente un estudio a pequeña escala para  establecer los parámetros de secado de  un  alimento para  animales denominado GARANVER,  compuesto por  una mezcla de cachaza, bagacillo, residuales líquidos (ácidos, alcalinos y azucarados), urea y miel final. El material fue expuesto al sol   sobre una  superficie pavimentada. Los tratamientos  utilizados  fueron  cuatro   densidades  (70;   85;   100   y  125   t/ha)   y  dos frecuencias  de  volteo  (cada una   y  cada  dos horas) replicados  cinco  veces. Como parámetro medible se tomó  la variación de  materia seca (MS) a las 24; 48 y 72 h. Los datos fueron evaluados en  un  análisis de  varianza de  clasificación simple con  arreglo factorial.  Posteriormente  se efectuó  el  secado  a  escala  comercial  empleando  dos densidades (70  y 125  t/ha)  y al material seco se le tomaron muestras  para  análisis microbiológicos. Después se almacenó durante seis meses y se controló mensualmente los componentes bromatológicos. Los resultados muestran la posibilidad de alcanzar un nivel de MS por encima del 85 % con la densidad de 70 t/ha a las 48 h con volteo cada 1 h y con  la  densidad de  80,  100  y 125 t/ha  el  periodo  se alarga  hasta 72  horas con ambas frecuencias  de  volteo.  De  manera semejante  se comportó el  secado a  escala comercial. Los análisis microbiológicos no arrojaron presencia de salmonella ni de organismos  proteolíticos.  Los componentes  nutritivos  se mantuvieron  estables  durante el periodo de almacenamiento