Breakdown of the Korringa Law of Nuclear Spin Relaxation in Metallic GaAs

We present nuclear spin relaxation measurements in GaAs epilayers using a new pump-probe technique in all-electrical, lateral spin-valve devices. The measured T1 times agree very well with NMR data available for T > 1 K. However, the nuclear spin relaxation rate clearly deviates from the well-established Korringa law expected in metallic samples and follows a sub-linear temperature dependence 1/T1 ~ T^0.6 for 0.1 K < T < 10 K. Further, we investigate nuclear spin inhomogeneities.Comment: 5 pages, 4 (color) figures. arXiv admin note: text overlap with arXiv:1109.633

High-Resolution Energy and Intensity Measurements with CVD Diamond at REX-ISOLDE

A novel beam instrumentation device for the HIE-REX (High In-tensity and Energy REX) upgrade has been developed and tested at the On-Line Isotope Mass Separator ISOLDE, located at the European Laboratory for Particle Physics (CERN). This device is based on CVD diamond detector technology and is used for measuring the beam intensity, particle counting and measuring the energy spectrum of the beam. An energy resolution of 0.6% was measured at a carbon ion energy of 22.8 MeV. This corresponds to an energy spread of ± 140 keV

A brief comparison of Simon and Simeck

Abstract. Simeck is a new lightweight block cipher design based on combining the Simon and Speck block cipher. While the design allows a smaller and more efficient hardware implementation, its security margins are not well understood. The lack of design rationals of its predecessors further leaves some uncertainty on the security of Simeck. In this work we give a short analysis of the impact of the design changes by comparing the lower bounds for differential and linear characteristics with Simon. We also give a comparison of the effort of finding those bounds, which surprisingly is significant less for Simeck while covering a larger number of rounds. Furthermore, we provide new differentials for Simeck which can cover more rounds compared to previous results on Simon. Based on this we mount key recovery attacks on 19/26/33 rounds of Simeck32/48/64, which also give insights on the reduced key guessing effort due to the different set of rotation constants

Homogene Al-Verteilung in synthetisch hergestellten Al-Goethiten

Goethit (α-FeOOH) ist eines der häufigsten Eisenoxide in Böden der gemäßigten Breiten, das sich vor allem durch die Verwitterung von eisenreichem Ausgangsgestein bildet. In Abhängigkeit der pedogenen Bildungsbedingungen kann es hierbei zum Einbau von Metallkationen in die Gitterstruktur kommen. Am häufigsten lässt sich der Austausch von Fe3+ durch Al3+detektieren, wobei im Allgemeinen davon ausgegangen wird, dass der Einbau durch isomorphen Ersatz erfolgt. Neuere Studien legen jedoch nahe, dass auch die Bildung von separaten Al-reichen Phasen an und innerhalb der Goethit-Struktur möglich sind (1). Für die Untersuchungen wurden Al-Goethite mit Al-Gehalten zwischen 0.1 und 7 % synthetisch hergestellt und mittels Infrarotspektroskopie (FTIR), Röntgendiffraktometrie (XRD) und Mößbauerspektroskopie mineralogisch charakterisiert. Um vorhandene Al-Akkumulationsbereiche auf dem Goethit zu visualisieren, wurde je 0.1 mg Probe auf Graphitträger aufgebracht und mittels Sekundärionen-Massenspektrometrie (NanoSIMS), Energiedispersiver Röntgenspektroskopie (EDX) und Rasterelektronenmikroskopie untersucht. Die Verwendung von NanoSIMS ermöglicht uns hierbei die Al-Verteilung mit einer hohen räumlichen Auflösung von ~ 100 nm darzustellen, wohingegen die Auflösung von EDX-Aufnahmen auf ~ 1 µm begrenzt ist. Durch die Gegenüberstellung beider bildgebender Verfahren ist darüber hinaus ein direkter Vergleich hinsichtlich der detektierbaren Al-Verteilung möglich. Die Auswertung der XRD- und FTIR-Spektren zeigt, dass es mit ansteigendem Al-Gehalt zu Gitterdefekten innerhalb der Goethit-Struktur kommt, wobei das Fehlen von separaten Al-Phasen in den Spektren als erste Hinweise für eine homogene Al-Verteilung angesehen werden kann. Zudem wird deutlich, dass vor allem bei niedrigen Al-Konzentrationen und der Untersuchung von Einzelmineralen, NanoSIMS-Aufnahmen gegenüber EDX-Aufnahmen vorzuziehen sind. Auf Grund der hohen räumlichen Auflösung und niedrigen Nachweisgrenze des NanoSIMS konnten wir auch für geringe Al-Gehalte die homogene räumliche Verteilung von Al nachweisen. Die Kombination von spektroskopischen und bildgebenden Verfahren ermöglicht somit die Schlussfolgerung, dass innerhalb des untersuchten Konzentrationsbereiches Al homogen in die Goethit-Struktur eingebaut ist

The 13

At nuclear fusion reactors, CVD diamond detectors are considered an advantageous solution for neutron flux monitoring. For such applications the knowledge of the cross section of neutron-induced nuclear reactions on natural carbon are of high importance. Especially the (n,α0) reactions, yielding the highest energy reaction products, are of relevance as they can be clearly distinguished in the spectrum. The 13C(n,α0)10Be cross section was measured relative to 12C(n,α0)9Be at the Van de Graaff facility of EC-JRC Geel, Belgium, at 14.3 MeV and 17.0 MeV neutron energies. The measurement was performed with an sCVD (single-crystal Chemical Vapor Deposition) diamond detector, where the detector material acted simultaneously as sample and as sensor. A novel data analysis technique, based on pulse-shape discrimination, allowed an efficient reduction of background events. The results of the measurement are presented and compared to previously published values for this cross-section

Hypofractionated stereotactic re-irradiation: treatment option in recurrent malignant glioma

BACKGROUND: Hypofractionated stereotactic radiotherapy (HFSRT) is one salvage treatment option in previously irradiated patients with recurrent malignant glioma. We analyzed the results of HFSRT and prognostic factors in a single-institution series. METHODS: Between 1997 and 2003, 19 patients with recurrent malignant glioma (14 glioblastoma on most recent histology, 5 anaplastic astrocytoma) were treated with HFSRT. The median interval from post-operative radiotherapy to HFSRT was 19 (range 3–116) months, the median daily single dose 5 (4–10) Gy, the median total dose 30 (20–30) Gy and the median planning target volume 15 (4–70) ml. RESULTS: The median overall survival (OS) was 9.3 (1.9-77.6+) months from the time of HFSRT, 15.4 months for grade III and 7.9 months for grade IV tumors (p = 0.029, log-rank test). Two patients were alive at 34.6 and 77.6 months. OS was longer after a total dose of 30 Gy (11.1 months) than after total doses of <30 Gy (7.4 months; p = 0.051). Of five (26%) reoperations, none was performed for presumed or histologically predominant radiation necrosis. Median time to tumor progression after HFSRT on imaging was 4.9 months (1.3 to 37.3) months. CONCLUSION: HFSRT with conservative total doses of no more than 30 Gy is safe and leads to similar OS times as more aggressive treatment schemes. In individual patients, HFSRT in combination with other salvage treatment modalities, was associated with long-term survival

Mind the Gap - A Closer Look at the Security of Block Ciphers against Differential Cryptanalysis

Resistance against differential cryptanalysis is an important design criteria for any modern block cipher and most designs rely on finding some upper bound on probability of single differential characteristics. However, already at EUROCRYPT'91, Lai et al. comprehended that differential cryptanalysis rather uses differentials instead of single characteristics. In this paper, we consider exactly the gap between these two approaches and investigate this gap in the context of recent lightweight cryptographic primitives. This shows that for many recent designs like Midori, Skinny or Sparx one has to be careful as bounds from counting the number of active S-boxes only give an inaccurate evaluation of the best differential distinguishers. For several designs we found new differential distinguishers and show how this gap evolves. We found an 8-round differential distinguisher for Skinny-64 with a probability of 2−56.932−56.93, while the best single characteristic only suggests a probability of 2−722−72. Our approach is integrated into publicly available tools and can easily be used when developing new cryptographic primitives. Moreover, as differential cryptanalysis is critically dependent on the distribution over the keys for the probability of differentials, we provide experiments for some of these new differentials found, in order to confirm that our estimates for the probability are correct. While for Skinny-64 the distribution over the keys follows a Poisson distribution, as one would expect, we noticed that Speck-64 follows a bimodal distribution, and the distribution of Midori-64 suggests a large class of weak keys

Integration of radiation oncology teaching in medical studies by German medical faculties due to the new licensing regulations: an overview and recommendations of the consortium academic radiation oncology of the German Society for Radiation Oncology (DEGRO)

The new Medical Licensing Regulations 2025 (Ärztliche Approbationsordnung, ÄApprO) will soon be passed by the Federal Council (Bundesrat) and will be implemented step by step by the individual faculties in the coming months. The further development of medical studies essentially involves an orientation from fact-based to competence-based learning and focuses on practical, longitudinal and interdisciplinary training. Radiation oncology and radiation therapy are important components of therapeutic oncology and are of great importance for public health, both clinically and epidemiologically, and therefore should be given appropriate attention in medical education. This report is based on a recent survey on the current state of radiation therapy teaching at university hospitals in Germany as well as the contents of the National Competence Based Learning Objectives Catalogue for Medicine 2.0 (Nationaler Kompetenzbasierter Lernzielkatalog Medizin 2.0, NKLM) and the closely related Subject Catalogue (Gegenstandskatalog, GK) of the Institute for Medical and Pharmaceutical Examination Questions (Institut für Medizinische und Pharmazeutische Prüfungsfragen, IMPP). The current recommendations of the German Society for Radiation Oncology (Deutsche Gesellschaft für Radioonkologie, DEGRO) regarding topics, scope and rationale for the establishment of radiation oncology teaching at the respective faculties are also included

The prognostic value of four interleukin-1 gene polymorphisms in caucasian women with breast cancer – a multicenter study

<p>Abstract</p> <p>Background</p> <p>The proinflammatory cytokine interleukin-1 (IL-1) is known to play an important role in the carcinogenesis of breast cancer. Although IL-1 gene polymorphisms were reported to be associated with increased risk of breast cancer, their influence on survival of Caucasian breast cancer patients remains to be shown.</p> <p>Methods</p> <p>We studied the influence of four common gene polymorphisms (<it>IL1A </it>-889C/T, <it>IL1B </it>-511C/T, <it>IL1B </it>+3953E1/E2, and <it>IL1RN </it>long/2) of the IL-1 family on survival in 262 Caucasian patients with breast cancer by univariate and multivariate survival analysis. The combined effect of the four gene polymorphisms on overall survival was studied by haplotype analysis.</p> <p>Results</p> <p>In the present study 38 cases of cancer related death and a median time of follow-up (range) of 55.3 (0.4–175.8) months was observed. <it>IL1RN </it>2/2 (homozygous mutant) gene polymorphism was associated with shortened disease free and overall survival in a univariate (p = 0.001 and p = 0.01, respectively) and multivariate analysis (p = 0.002, Odds Ratio [95% Confidence Interval] = 3.6 [1.6–8.0] and p = 0.05, Odds Ratio = 3.0 [1.1–9.3], respectively). Presence of the homozygous mutant genotype of the <it>IL1A </it>-889 and <it>IL1B </it>+3953 gene polymorphism was associated with overall survival in the univariate (p = 0.004 and p = 0.002, respectively), but not in the multivariate analysis. No association was observed between all possible haplotype combinations and overall survival.</p> <p>Conclusion</p> <p>Carriage of the mutant alleles of <it>IL1RN </it>was independently associated with shortened disease free and overall survival rates in Caucasian patients with breast cancer.</p