High-accuracy drilling with an image guided light weight robot: autonomous versus intuitive feed control.

PURPOSE: Assistance of robotic systems in the operating room promises higher accuracy and, hence, demanding surgical interventions become realisable (e.g. the direct cochlear access). Additionally, an intuitive user interface is crucial for the use of robots in surgery. Torque sensors in the joints can be employed for intuitive interaction concepts. Regarding the accuracy, they lead to a lower structural stiffness and, thus, to an additional error source. The aim of this contribution is to examine, if an accuracy needed for demanding interventions can be achieved by such a system or not. METHODS: Feasible accuracy results of the robot-assisted process depend on each work-flow step. This work focuses on the determination of the tool coordinate frame. A method for drill axis definition is implemented and analysed. Furthermore, a concept of admittance feed control is developed. This allows the user to control feeding along the planned path by applying a force to the robots structure. The accuracy is researched by drilling experiments with a PMMA phantom and artificial bone blocks. RESULTS: The described drill axis estimation process results in a high angular repeatability ([Formula: see text]). In the first set of drilling results, an accuracy of [Formula: see text] at entrance and [Formula: see text] at target point excluding imaging was achieved. With admittance feed control an accuracy of [Formula: see text] at target point was realised. In a third set twelve holes were drilled in artificial temporal bone phantoms including imaging. In this set-up an error of [Formula: see text] and [Formula: see text] was achieved. CONCLUSION: The results of conducted experiments show that accuracy requirements for demanding procedures such as the direct cochlear access can be fulfilled with compliant systems. Furthermore, it was shown that with the presented admittance feed control an accuracy of less then [Formula: see text] is achievable.

Non-target effects of a glyphosate-based herbicide on Common toad larvae (Bufo bufo, Amphibia) and associated algae are altered by temperature.

BACKGROUND: Glyphosate-based herbicides are the most widely used pesticides in agriculture, horticulture, municipalities and private gardens that can potentially contaminate nearby water bodies inhabited by amphibians and algae. Moreover, the development and diversity of these aquatic organisms could also be affected by human-induced climate change that might lead to more periods with extreme temperatures. However, to what extent non-target effects of these herbicides on amphibians or algae are altered by varying temperature is not well known. METHODS: We studied effects of five concentrations of the glyphosate-based herbicide formulation Roundup PowerFlex (0, 1.5, 3, 4 mg acid equivalent glyphosate L-1 as a one time addition and a pulse treatment of totally 4 mg a.e. glyphosate L-1) on larval development of Common toads (Bufo bufo, L.; Amphibia: Anura) and associated algae communities under two temperature regimes (15 vs. 20 °C). RESULTS: Herbicide contamination reduced tail growth (-8%), induced the occurrence of tail deformations (i.e. lacerated or crooked tails) and reduced algae diversity (-6%). Higher water temperature increased tadpole growth (tail and body length (tl/bl) +66%, length-to-width ratio +4%) and decreased algae diversity (-21%). No clear relation between herbicide concentrations and tadpole growth or algae density or diversity was observed. Interactive effects of herbicides and temperature affected growth parameters, tail deformation and tadpole mortality indicating that the herbicide effects are temperature-dependent. Remarkably, herbicide-temperature interactions resulted in deformed tails in 34% of all herbicide treated tadpoles at 15 °C whereas no tail deformations were observed for the herbicide-free control at 15 °C or any tadpole at 20 °C; herbicide-induced mortality was higher at 15 °C but lower at 20 °C. DISCUSSION: These herbicide- and temperature-induced changes may have decided effects on ecological interactions in freshwater ecosystems. Although no clear dose-response effect was seen, the presence of glyphosate was decisive for an effect, suggesting that the lowest observed effect concentration (LOEC) in our study was 1.5 mg a.e. glyphosate L-1 water. Overall, our findings also question the relevance of pesticide risk assessments conducted at standard temperatures.

Prospective evaluation of quality of life after permanent prostate brachytherapy with I-125: importance of baseline symptoms and of prostate-V150.

BACKGROUND AND PURPOSE: Detailed knowledge of quality of life (QoL) after permanent I-125 brachytherapy may aid in counselling patients with early-stage prostate cancer. MATERIALS AND METHODS: Seventy-four consecutive patients with low-risk prostate cancer were asked to complete the EORTC QLQ-C30 questionnaire with the prostate-specific PR25 module before implant, four weeks and one year after implant (response rates 97%, 88% and 89%, respectively). Implant characteristics were correlated with QoL scores. RESULTS: Global QoL was stable from pre-treatment to one year after implant and similar to age-adjusted scores of healthy controls. Significant changes versus baseline in QLQ-C30 domains were worsened social function at four weeks, increased constipation at four weeks and at one year and improved emotional function at one year. PR25 urinary symptoms were significantly increased at four weeks and, despite some improvement, at one year; bowel symptoms were slightly increased. Both types of symptoms were most strongly related with pre-treatment symptom scores. Prostate-V150 was the only implant parameter significantly associated with both urinary and bowel symptoms at four weeks and one year. CONCLUSIONS: Limiting the high-dose subvolume in the prostate may be beneficial to reduce urinary and bowel symptoms but the major determinant of symptoms after I-125 implant is the baseline symptom level.