We study deformations of Z 2 × Z 2 (shift-)orientifolds in four dimensions in the presence of both uniform Abelian internal magnetic fields and quantized NS-NS B ab backgrounds, that are shown to be equivalent to asymmetric shift-orbifold projections. These models are related by T -duality to orientifolds with D-branes intersecting at angles. As in corresponding six-dimensional examples, D9-branes magnetized along two internal directions acquire a charge with respect to the R-R six form, contributing to the tadpole of the orthogonal D5-branes ("brane transmutation"). The resulting models exhibit rank reduction of the gauge group and multiple matter families, due both to the quantized B ab and to the background magnetic fields. Moreover, the lowenergy spectra are chiral and anomaly free if additional D5-branes longitudinal to the magnetized directions are present, and if there are no Ramond-Ramond tadpoles in the corresponding twisted sectors of the undeformed models.

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The project ALTEA-shield/survey is part of an European Space Agency (ESA) -ILSRA (International Life Science Research Announcement) program and provides a detailed study of the International Space Station (ISS) (USLab and partly Columbus) radiation environment. The experiment spans over 2 years, from September 20, 2010 to September 30, 2012, for a total of about 1.5 years of effective measurements. The ALTEA detector system measures all heavy ions above helium and, to a limited extent, hydrogen and helium (respectively, in 25 Mev-45 MeV and 25 MeV/n-250 MeV/n energy windows) while tracking every individual particle. It measures independently the radiation along the three ISS coordinate axes. The data presented consist of flux, dose, and dose equivalent over the time of investigation, at the different surveyed locations. Data are selected from the different geographic regions (low and high latitudes and South Atlantic Anomaly, SAA). Even with a limited acceptance window for the proton contribution, the flux/dose/dose equivalent results as well as the radiation spectra provide information on how the radiation risks change in the different surveyed sites. The large changes in radiation environment found among the measured sites, due to the different shield/mass distribution, require a detailed Computer-Aided Design (CAD) model to be used together with these measurements for the validation of radiation models in space habitats. Altitude also affects measured radiation, especially in the SAA. In the period of measurements, the altitude (averaged over each minute) ranged from 339 km to 447 km. Measurements show the significant shielding effect of the ISS truss, responsible for a consistent amount of reduction in dose equivalent (and so in radiation quality). Measured Galactic Cosmic Ray (GCR) dose rates at high latitude range from 0.354 ± 0.002 nGy/s to 0.770 ± 0.006 nGy/s while dose equivalent from 1.21 ± 0.04 nSv/s to 6.05 ± 0.09 nSv/s. The radiation variation over the SAA is studied. Even with the reduced proton sensitivity, the high day-by-day variability, as well as the strong altitude dependence is clearly observed. The ability of filtering out this contribution from the data is presented as a tool to construct a radiation data set well mimicking deep space radiation, useful for model validations and improvements.