A new optimization method using a compressed sensing inspired solver for real-time LDR-brachytherapy treatment planning.

This work discusses a novel strategy for inverse planning in low dose rate brachytherapy. It applies the idea of compressed sensing to the problem of inverse treatment planning and a new solver for this formulation is developed. An inverse planning algorithm was developed incorporating brachytherapy dose calculation methods as recommended by AAPM TG-43. For optimization of the functional a new variant of a matching pursuit type solver is presented. The results are compared with current state-of-the-art inverse treatment planning algorithms by means of real prostate cancer patient data. The novel strategy outperforms the best state-of-the-art methods in speed, while achieving comparable quality. It is able to find solutions with comparable values for the objective function and it achieves these results within a few microseconds, being up to 542 times faster than competing state-of-the-art strategies, allowing real-time treatment planning. The sparse solution of inverse brachytherapy planning achieved with methods from compressed sensing is a new paradigm for optimization in medical physics. Through the sparsity of required needles and seeds identified by this method, the cost of intervention may be reduced.

[Efficacy and sustainability of a smoking prevention program for pupils--"ohnekippe"]. / Wirksamkeit und Nachhaltigkeit eines Raucher-präventionsprogramm für Schüler--"ohnekippe"

BACKGROUND: Since 2000 the Thoraxklinik Heidelberg offers the primary smoking prevention program "ohnekippe" for children aged 12-14 years. This program was scientifically evaluated to test its efficacy and sustainability. METHODS: All pupils participating in this prevention program (n=1427) were asked to complete a written survey regarding their smoking behaviour at the time of intervention (baseline) and after one year. A control group (n=1412) without intervention from comparable schools and grades were questioned in parallel. Afterwards the program was modified with active involvement of schools and then data regarding smoking prevalence of young people were compared based on the microcensus 2005 and 2009. RESULTS: 187 (13,4 %) pupils in the intervention and 215 (15,4 %) pupils in the control group were smokers at baseline. One year after, the number of regular and occasional smokers had increased from 11.2 % to 21.2 % in both groups without significant differences. Besides age and initial smoking status the "peer group" had important influence on smoking behaviour of young people. After modifying the program the number of smoking young people in the catchment area of "ohnekippe" has decreased significantly (7.8 %). Overall smoking prevalence in this age group was much lower (11,8 %) than in the rest of Baden-Württemberg (16.0 %) and of Germany (17.5 %). CONCLUSION: Smoking prevention programs for young people can be effective if they are appropriately designed. Not only one prevention event, but intensive preparation and follow-up in schools as well as involvement of the "peer group" is essential for a successful intervention. After appropriate modification the smoking prevention program "ohnekippe" shows highly promising success.

High-throughput characterization of stresses in thin film materials libraries using Si cantilever array wafers and digital holographic microscopy.

We report the development of an advanced high-throughput stress characterization method for thin film materials libraries sputter-deposited on micro-machined cantilever arrays consisting of around 1500 cantilevers on 4-inch silicon-on-insulator wafers. A low-cost custom-designed digital holographic microscope (DHM) is employed to simultaneously monitor the thin film thickness, the surface topography and the curvature of each of the cantilevers before and after deposition. The variation in stress state across the thin film materials library is then calculated by Stoney's equation based on the obtained radii of curvature of the cantilevers and film thicknesses. DHM with nanometer-scale out-of-plane resolution allows stress measurements in a wide range, at least from several MPa to several GPa. By using an automatic x-y translation stage, the local stresses within a 4-inch materials library are mapped with high accuracy within 10 min. The speed of measurement is greatly improved compared with the prior laser scanning approach that needs more than an hour of measuring time. A high-throughput stress measurement of an as-deposited Fe-Pd-W materials library was evaluated for demonstration. The fast characterization method is expected to accelerate the development of (functional) thin films, e.g., (magnetic) shape memory materials, whose functionality is greatly stress dependent.

[Attitude of the elderly to the etiology of memory disorders]. / Vorstellungen in der Altenbevölkerung über die Ursachen von Gedächtnisstörungen.

PURPOSE: The early recognition of dementia assumes increasing importance. Lay beliefs on the causes of loss of memory play a major part in this regard as they have shown to determine help-seeking behaviour. METHOD: 720 persons aged 75 or older were questioned on their beliefs on the causes of cognitive deficits in the context of the Leipzig Longitudinal Study of the Aged (LEILA 75+). RESULTS: Almost one-third of the respondents mentioned exclusively biological causes, vascular lesions coming first. One quarter of those questioned ascribed memory deficits to non-biological factors. Every tenth person suspected that they result from a combination of both. One quarter of the elderly did not know any answer. DISCUSSION: The results are contrasted with outcomes of epidemiological dementia research. It is argued that increasing and better quality information of the public are urgently required.

Insulysin hydrolyzes amyloid beta peptides to products that are neither neurotoxic nor deposit on amyloid plaques.

Insulysin (EC. 3.4.22.11) has been implicated in the clearance of beta amyloid peptides through hydrolytic cleavage. To further study the action of insulysin on Abeta peptides recombinant rat insulysin was used. Cleavage of both Abeta(1-40) and Abeta(1-42) by the recombinant enzyme was shown to initially occur at the His(13)-His(14), His(14)-Gln(15), and Phe(19)-Phe(20) bonds. This was followed by a slower cleavage at the Lys(28)-Gly(29), Val(18)-Phe(19), and Phe(20)-Ala(21) positions. None of the products appeared to be further metabolized by insulysin. Using a rat cortical cell system, the action of insulysin on Abeta(1-40) and Abeta(1-42) was shown to eliminate the neurotoxic effects of these peptides. Insulysin was further shown to prevent the deposition of Abeta(1-40) onto a synthetic amyloid. Taken together these results suggest that the use of insulysin to hydrolyze Abeta peptides represents an alternative gene therapeutic approach to the treatment of Alzheimer's disease.

Tissue plasminogen activator requires plasminogen to modulate amyloid-beta neurotoxicity and deposition.

Tissue plasminogen (plgn) activator (tPA) modulates neuronal death in models of stroke, excitotoxicity, and oxidative stress. Amyloid-beta (Abeta) appears central to Alzheimer's disease and is neurotoxic to neurons in vitro. Here, we evaluate tPA effects on Abeta toxicity. We report that tPA alone had no effect on Abeta toxicity. However, in combination with plgn, tPA reduced Abeta toxicity in a robust fashion. Moreover, the combined tPA and plgn treatment markedly inhibited Abeta accumulation. The addition of phenylmethylsulfonyl fluoride, a serine protease inhibitor, to a sample of tPA, plgn, and Abeta resulted in a marked reduction of Abeta degradation. We interpret the actions of tPA and plgn within the context of the ability of plasmin to degrade Abeta.

Modeling of Growth of Lactobacillus sanfranciscensis and Candida milleri in Response to Process Parameters of Sourdough Fermentation.

We investigated the effect of the ecological factors pH, temperature, ionic strength, and lactate, acetate, and ethanol levels on Candida milleri and two strains of Lactobacillus sanfranciscensis, organisms representative of the microflora of sourdough. A mathematical model describing the single and combined effects of these factors on the growth of these organisms was established in accordance with the following criteria: quality of fit, biological significance of the parameters, and applicability of the in vitro data to in situ processes. The growth rates of L. sanfranciscensis LTH1729 and LTH2581 were virtually identical under all conditions tested. These organisms tolerated >160 mmol of undissociated acetic acid per liter. Growth occurred in the pH range of 3.9 to 6.7 and was completely inhibited by 4% NaCl. C. milleri had a lower optimum temperature for growth (27 degreesC) than the lactobacilli. The growth of the yeast was not affected by pH in the range of 3.5 to 7, and up to 8% NaCl was tolerated. Complete inhibition of growth occurred at 150 mmol of undissociated acetic acid per liter, but acetate at concentrations of up to 250 mmol/liter exerted virtually no effect. The model provides insight into factors contributing to the stability of the sourdough microflora and can facilitate the design of novel sourdough processes.