Reciprocal Associations between Electronic Media Use and Behavioral Difficulties in Preschoolers.

The use of electronic media has increased substantially and is already observable in young children. The present study explored associations of preschoolers’ use of electronic media with age, gender, and socio-economic status, investigated time trends, and examined reciprocal longitudinal relations between children’s use of electronic media and their behavioral difficulties. The study participants included 527 German two- to six-year-old children whose parents had provided information on their use of electronic media and their behavioral difficulties at two time points, with approximately 12 months between baseline and follow-up.

Amplification of Relativistic Electron Bunches by Acceleration in Laser Fields.

Direct acceleration of electrons in a coherent, intense light field is revealed by a remarkable increase of the electron number in the MeV energy range. Laser irradiation of thin polymer foils with a peak intensity of ∼1×10^{20}  W/cm^{2} releases electron bunches along the laser propagation direction that are postaccelerated in the partly transmitted laser field. They are decoupled from the laser field at high kinetic energies, when a second foil target at an appropriate distance prevents their subsequent deceleration in the declining laser field.

Enhanced proton acceleration by an ultrashort laser interaction with structured dynamic plasma targets.

We experimentally demonstrate a notably enhanced acceleration of protons to high energy by relatively modest ultrashort laser pulses and structured dynamical plasma targets. Realized by special deposition of snow targets on sapphire substrates and using carefully planned prepulses, high proton yields emitted in a narrow solid angle with energy above 21 MeV were detected from a 5 TW laser. Our simulations predict that using the proposed scheme protons can be accelerated to energies above 150 MeV by 100 TW laser systems.

Thomson spectrometer-microchannel plate assembly calibration for MeV-range positive and negative ions, and neutral atoms.

We report on the absolute calibration of a microchannel plate (MCP) detector, used in conjunction with a Thomson parabola spectrometer. The calibration delivers the relation between a registered count numbers in the CCD camera (on which the MCP phosphor screen is imaged) and the number of ions incident on MCP. The particle response of the MCP is evaluated for positive, negative, and neutral particles at energies below 1 MeV.

Ethanol (C2H5OH) spray of sub-micron droplets for laser driven negative ion source.

Liquid ethanol (C(2)H(5)OH) was used to generate a spray of sub-micron droplets. Sprays with different nozzle geometries have been tested and characterised using Mie scattering to find scaling properties and to generate droplets with different diameters within the spray. Nozzles having throat diameters of 470 μm and 560 μm showed generation of ethanol spray with droplet diameters of (180 ± 10) nm and (140 ± 10) nm, respectively.