Identifying core MRI sequences for reliable automatic brain metastasis segmentation

BACKGROUND Many automatic approaches to brain tumor segmentation employ multiple magnetic resonance imaging (MRI) sequences. The goal of this project was to compare different combinations of input sequences to determine which MRI sequences are needed for effective automated brain metastasis (BM) segmentation. METHODS We analyzed preoperative imaging (T1-weighted sequence ± contrast-enhancement (T1/T1-CE), T2-weighted sequence (T2), and T2 fluid-attenuated inversion recovery (T2-FLAIR) sequence) from 339 patients with BMs from seven centers. A baseline 3D U-Net with all four sequences and six U-Nets with plausible sequence combinations (T1-CE, T1, T2-FLAIR, T1-CE + T2-FLAIR, T1-CE + T1 + T2-FLAIR, T1-CE + T1) were trained on 239 patients from two centers and subsequently tested on an external cohort of 100 patients from five centers. RESULTS The model based on T1-CE alone achieved the best segmentation performance for BM segmentation with a median Dice similarity coefficient (DSC) of 0.96. Models trained without T1-CE performed worse (T1-only: DSC = 0.70 and T2-FLAIR-only: DSC = 0.73). For edema segmentation, models that included both T1-CE and T2-FLAIR performed best (DSC = 0.93), while the remaining four models without simultaneous inclusion of these both sequences reached a median DSC of 0.81-0.89. CONCLUSIONS A T1-CE-only protocol suffices for the segmentation of BMs. The combination of T1-CE and T2-FLAIR is important for edema segmentation. Missing either T1-CE or T2-FLAIR decreases performance. These findings may improve imaging routines by omitting unnecessary sequences, thus allowing for faster procedures in daily clinical practice while enabling optimal neural network-based target definitions

Ty1 integrase overexpression leads to integration of non-Ty1 DNA fragments into the genome of Saccharomyces cerevisiae

The integrase of the Saccharomyces cerevisiae retrotransposon Ty1 integrates Ty1 cDNA into genomic DNA likely via a transesterification reaction. Little is known about the mechanisms ensuring that integrase does not integrate non-Ty DNA fragments. In an effort to elucidate the conditions under which Ty1 integrase accepts non-Ty DNA as substrate, PCR fragments encompassing a selectable marker gene were transformed into yeast strains overexpressing Ty1 integrase. These fragments do not exhibit similarity to Ty1 cDNA except for the presence of the conserved terminal dinucleotide 5′-TG-CA-3′. The frequency of fragment insertion events increased upon integrase overexpression. Characterization of insertion events by genomic sequencing revealed that most insertion events exhibited clear hallmarks of integrase-mediated reactions, such as 5 bp target site duplication and target site preferences. Alteration of the terminal dinucleotide abolished the suitability of the PCR fragments to serve as substrates. We hypothesize that substrate specificity under normal conditions is mainly due to compartmentalization of integrase and Ty cDNA, which meet in virus-like particles. In contrast, recombinant integrase, which is not confined to virus-like particles, is able to accept non-Ty DNA, provided that it terminates in the proper dinucleotide sequence

Government Size and Unemployment: Evidence from Industrial Countries

Using data from 19 industrial countries for the period 1985 to 2002, this paper analyzes how the size of the government sector affects unemployment. Controlling for the impact of the business cycle as well as for the impact of all major labor market institutions and unobserved country effects, we find that a large government sector is likely to increase unemployment. It appears to have a particularly detrimental effect on women and the low skilled and to substantially increase long-term unemployment. It seems that dominant stateowned enterprises, a large share of public investment in total investment as well as high top marginal income tax rates and low income threshold levels at which they apply are particularly detrimental. Copyright Springer Science+Business Media, Inc. 2006

The effects of hiring and firing regulation on unemployment and employment: evidence based on survey data

We use the results of surveys among senior business executives to measure the strictness of hiring and firing regulations. The survey data are more likely than objective indicators (used in almost all previous studies) to correctly capture the de facto strictness of these regulations and their relevance to the performance of the labour market. Using data from 19 industrial countries for the period 1992 to 2002, we find that more flexible regulations are likely to lower unemployment and to increase employment rates. While the effects on the general population appear to be modest, the effects on female, young and low-skilled workers seem to be substantial.

Business regulation and labor market performance around the world

Corruption, Employment, Regulation, Unemployment, J21, J23, J64, K23, L51,

The quality of the legal system and labor market performance around the world

Employment, Legal system, Rule of law, Unemployment, E24, J23, J64, K00, K40,

SRF Gun Cavity R&D at DESY

SRF Gun Cavity is an ongoing accelerator R&D Project at DESY, being developed since several years. Currently several SRF gun cavity prototypes were simulated, built and tested in our Lab and elsewhere. Lately the 1.6 cells niobium cavity with Pb thin film cathode was tested in a vertical cryostat with a different cathode plug configurations. Cathode plug design was improved, as well as SRF gun cavity cleaning procedures. Results ofthe last cavity performance tests are presented