A manifestly gauge-invariant description of interaction of atomic systems with strong fields in the dipole approximation

We propose a new type of gauge-invariant expansion of the ionization probability amplitudes of atoms by short pulses of electromagnetic radiation. Contrary to previous gauge-invariant approaches to this problem it does not require different partitions of the total Hamiltonian depending on the choice of gauge. In a natural way the atomic potential is treated as perturbation acting on an electron interacting with strong pulse. Whereas this is a standard assumption of strong field approximation (SFA), we show that grouping consequently together \textit{all} terms of the same order in the atomic potential results in the expansion of the amplitude which is gauge invariant \textit{order by order}, and not only in the limit of infinite series. In this approach, which is illustrated by numerical examples, the "direct ionization" and "rescattering" contributions are different from those commonly used in SFA - calculations.Comment: 7 pages, 4 figure

Combining protective clothes with human body models for finite element ballistic impact simulations

The ballistic deformation of an ultra-high-molecular-weight (UHMW) polyethylene (PE) composite has been subjected numerically to a multi-layered soft ballistic fabric package modelled upon the body contours of the Global Human Body Models Consortium (GHBMC) human body models M50-P and F05-P. The results of the clothing-body-interaction have been investigated and compared to the behavior of anthropomorphic surrogate models made from ballistic clay. For building the fabric model in donned shape, a single ply of woven fabric material has been converted upon the anthropomorphic body contour by subjecting it to a quasi-deep drawing process. After the fabric deformation, the shaped layer was duplicated 20 times and shifted outwards to build the fabric model, representing a multi-layered soft ballistic fabric package. The results of the ballistic impact simulation show that the response of the human body models (HBMs) is much more compliant than the behavior of the surrogate models. The deformation of the female HBM in terms of penetration depth and diameter of the affected impact region is slightly more severe than the deformation of the male counterpart with respect to identical impact conditions

Linear subspaces, symbolic powers and Nagata type conjectures

Prompted by results of Guardo, Van Tuyl and the second author for lines in projective 3 space, we develop asymptotic upper bounds for the least degree of a homogeneous form vanishing to order at least m on a union of disjoint r dimensional planes in projective n space for n at least 2r+1. These considerations lead to new conjectures that suggest that the well known conjecture of Nagata for points in the projective plane is not sporadic, but rather a special case of a more general phenomenon.Comment: 19 pages; made many minor improvements to exposition; one major improvement: replaced an example with 9 lines in P^4 by a family of examples with (n-1)^{n-2} lines in P^n for n >=

A novel ferroelectric Rashba semiconductor

Fast, reversible, and low-power manipulation of the spin texture is crucial for next generation spintronic devices like non-volatile bipolar memories, switchable spin current injectors or spin field effect transistors. Ferroelectric Rashba semiconductors (FERSC) are the ideal class of materials for the realization of such devices. Their ferroelectric character enables an electronic control of the Rashba-type spin texture by means of the reversible and switchable polarization. Yet, only very few materials are established to belong to this class of multifunctional materials. Here, Pb$_{1−x}$Ge$_{x}$Te is unraveled as a novel FERSC system down to nanoscale. The ferroelectric phase transition and concomitant lattice distortion are demonstrated by temperature dependent X-ray diffraction, and their effect on electronic properties are measured by angle-resolved photoemission spectroscopy. In few nanometer-thick epitaxial heterostructures, a large Rashba spin-splitting is exhibiting a wide tuning range as a function of temperature and Ge content. This work defines Pb$_{1−x}$Ge$_{x}$Te as a high-potential FERSC system for spintronic applications

Mitochondria-Targeted Antioxidants SkQ1 and MitoTEMPO Failed to Exert a Long-Term Beneficial Effect in Murine Polymicrobial Sepsis

Mitochondrial-derived reactive oxygen species have been deemed an important contributor in sepsis pathogenesis. We investigated whether two mitochondria-targeted antioxidants (mtAOX; SkQ1 and MitoTEMPO) improved long-term outcome, lessened inflammation, and improved organ homeostasis in polymicrobial murine sepsis. 3-month-old female CD-1 mice (n = 90) underwent cecal ligation and puncture (CLP) and received SkQ1 (5 nmol/kg), MitoTEMPO (50 nmol/kg), or vehicle 5 times post-CLP. Separately, 52 SkQ1-treated CLP mice were sacrificed at 24 h and 48 h for additional endpoints. Neither MitoTEMPO nor SkQ1 exerted any protracted survival benefit. Conversely, SkQ1 exacerbated 28-day mortality by 29%. CLP induced release of 10 circulating cytokines, increased urea, ALT, and LDH, and decreased glucose but irrespectively of treatment. Similar occurred for CLP-induced lymphopenia/neutrophilia and the NO blood release. At 48 h post-CLP, dying mice had approximately 100-fold more CFUs in the spleen than survivors, but this was not SkQ1 related. At 48 h, macrophage and granulocyte counts increased in the peritoneal lavage but irrespectively of SkQ1. Similarly, hepatic mitophagy was not altered by SkQ1 at 24 h. The absence of survival benefit of mtAOX may be due to the extended treatment and/or a relatively moderate-risk-of-death CLP cohort. Long-term effect of mtAOX in abdominal sepsis appears different to sepsis/inflammation models arising from other body compartments