Cube-Cut: Vertebral Body Segmentation in MRI-Data through Cubic-Shaped Divergences

In this article, we present a graph-based method using a cubic template for volumetric segmentation of vertebrae in magnetic resonance imaging (MRI) acquisitions. The user can define the degree of deviation from a regular cube via a smoothness value Delta. The Cube-Cut algorithm generates a directed graph with two terminal nodes (s-t-network), where the nodes of the graph correspond to a cubic-shaped subset of the image's voxels. The weightings of the graph's terminal edges, which connect every node with a virtual source s or a virtual sink t, represent the affinity of a voxel to the vertebra (source) and to the background (sink). Furthermore, a set of infinite weighted and non-terminal edges implements the smoothness term. After graph construction, a minimal s-t-cut is calculated within polynomial computation time, which splits the nodes into two disjoint units. Subsequently, the segmentation result is determined out of the source-set. A quantitative evaluation of a C++ implementation of the algorithm resulted in an average Dice Similarity Coefficient (DSC) of 81.33% and a running time of less than a minute.Comment: 23 figures, 2 tables, 43 references, PLoS ONE 9(4): e9338

Going NUTS: The Effect of EU Structural Funds on Regional Performance

The European Union (EU) provides grants to disadvantaged regions of member states to allow them to catch up with the EU average. Under the Objective 1 scheme, NUTS2 regions with a GDP per capita level below 75% of the EU average qualify for structural funds transfers from the central EU budget. This rule gives rise to a regression-discontinuity design that exploits the discrete jump in the probability of EU transfer receipt at the 75% threshold. Additional variability arises for smaller regional aggregates - so-called NUTS3 regions - which are nested in a NUTS2 mother region. Whereas some relatively rich NUTS3 regions may receive EU funds because their NUTS2 mother region qualifies, other relatively poor NUTS3 regions may not receive EU funds because their NUTS2 mother region does not qualify. We find positive growth effects of Objective 1 funds, but no employment effects. A simple cost-benefit calculation suggests that Objective 1 transfers are not only effective, but also cost-efficient.structural funds, regional growth, regression discontinuity design, quasi-randomized experiment

Regulation of Cx45 hemichannels mediated by extracellular and intracellular calcium

Connexin45 (Cx45) hemichannels (HCs) open in the absence of Ca2+ and close in its presence. To elucidate the underlying mechanisms, we examined the role of extra- and intracellular Ca2+ on the electrical properties of HCs. Experiments were performed on HeLa cells expressing Cx45 using electrical (voltage clamp) and optical (Ca2+ imaging) methods. HCs exhibit a time- and voltage-dependent current (I hc), activating with depolarization and inactivating with hyperpolarization. Elevation of [Ca2+]o from 20nM to 2μM reversibly decreases I hc, decelerates its rate of activation, and accelerates its deactivation. Our data suggest that [Ca2+]o modifies the channel properties by adhering to anionic sites in the channel lumen and/or its outer vestibule. In this way, it blocks the channel pore and reversibly lowers I hc and modifies its kinetics. Rapid lowering of [Ca2+]o from 2mM to 20nM, achieved early during a depolarizing pulse, led to an outward I hc that developed with virtually no delay and grew exponentially in time paralleled by unaffected [Ca2+]i. A step increase of [Ca2+]i evoked by photorelease of Ca2+ early during a depolarizing pulse led to a transient decrease of I hc superimposed on a growing outward I hc; a step decrease of [Ca2+]i elicited by photoactivation of a Ca2+ scavenger provoked a transient increase in I hc. Hence, it is tempting to assume that Ca2+ exerts a direct effect on Cx45 hemichannel

Free-living flatworms under the knife: past and present

Traditionally, regeneration research has been closely tied to flatworm research, as flatworms (Plathelminthes) were among the first animals where the phenomenon of regeneration was discovered. Since then, the main focus of flatworm regeneration research was on triclads, for which various phenomena were observed and a number of theories developed. However, free-living flatworms encompass a number of other taxa where regeneration was found to be possible. This review aims to display and to compare regeneration in all major free-living flatworm taxa, with special focus on a new player in the field of regeneration, Macrostomum lignano (Macrostomorpha). Findings on the regeneration capacity of this organism provide clues for links between regeneration and (post-)embryonic development, starvation, and asexual reproduction. The role of the nervous system and especially the brain for regeneration is discussed, and similarities as well as particularities in regeneration among free-living flatworms are pointed out

Simulation of sensory-evoked signal flow in anatomically realistic models of neural networks

In this thesis, a new concept for development and simulation of anatomically and functionally constrained models of signal flow in neural networks is described. This approach consists of the following tools: 1. A standardized anatomical reference frame of the brain region studied and registration methods to integrate anatomical data from different experiments with the highest precision possible. 2. A method for determining morphological neuron types to allow correlation between measurements of the morphology and functional responses of individual neurons. 3. A tool to build an average three-dimensional (3D) statistical model of the neural networks in a brain region based on a representative sparse sample of all neuron types present in the brain region. This model contains 3D morphological models for every neuron in the brain region, as well as the total number and 3D distribution of synaptic contacts between them. 4. A method to activate the network based on measured responses of different neuron types, and to simulate the response of individual neurons representative of different cell types within this network model. The feasibility and validity of this process is demonstrated on the example of rat vibrissal cortex. The 3D model of this primary sensory area in cortex contains ∼ 530,000 neurons of 16 different types and ∼ 6 × 10^9 thalamocortical and intracortical synapses. Activation of this model with functional responses measured after whisker touch and simulation of the responses of different neuron types shows that the simulated model responses match experimental measurements. This allowed investigating how robust sensory-evoked responses after different sensory stimuli are formed in different neuron types using computer simulations, and to make predictions to experimentally test these hypotheses.Diese Dissertation beschreibt einen neuartigen Ansatz zur Entwicklung und Simulation von Modellen des Signalflusses in neuronalen Netzwerken unter anatomisch und funktionell realistischen Randbedingungen. Dieser Ansatz besteht aus den folgenden Methoden: 1. Ein standardisiertes anatomisches Referenzsystem der betrachteten Hirnregion und Registrierungsmethoden die es erlauben anatomische Daten aus unterschiedlichen Experimenten mit höchstmöglicher Genauigkeit zu integrieren. 2. Eine Methode zur Bestimmung morphologischer Typen von Nervenzellen um Messungen von der Morphologie und funktioneller Antworten einzelner Nervenzellen in Bezug zu setzen. 3. Eine Methode um ein mittleres dreidimensionales (3D) statistisches Modell der neuronalen Netzwerke in einer Hirnregion zu bauen, das auf einer repräsentativen Stichprobe aller Nervenzelltypen in dieser Hirnregion beruht. Dieses Modell beinhaltet 3D morphologische Modelle für jede Nervenzelle in der Hirnregion, und die Zahl und 3D Verteilung synaptischer Verknüpfungen zwischen diesen. 4. Eine Methode um dieses Netzwerk aufgrund von gemessenen Antworten unterschiedlicher Nervenzelltypen zu aktivieren, und die Antwort einzelner repräsentativer Nervenzellen bestimmten Typs innerhalb dieses Netzwerkmodells zu simulieren. Die Machbarkeit und Gültigkeit dieses Ansatzes wird am Beispiel des Tasthaarsystems im Kortex der Ratte demonstriert. Das 3D Modell dieses primären sensorischen Kortex enthält ∼ 530000 Nervenzellen von 16 unterschiedlichen Typen und ∼ 6 × 10^9 thalamokortikale und intrakortikale Synapsen. Aktivierung dieses Modells mit gemessen funktionellen Antworten auf passive Berührung eines Schnurrhaares und Simulation der Antworten unterschiedlicher Nervenzelltypen zeigt dass die simulierten Antworten mit experimentellen Messungen übereinstimmen. Dies erlaubt es mit Hilfe von Computersimulationen zu untersuchen wie robuste Antworten auf unterschiedliche Sinnesreize in unterschiedlichen Nervenzelltypen entstehen, und experimentell überprüfbare Vorhersagen zu machen

Coulomb Blockade of a Three-terminal Quantum Dot

We study an interacting single-level quantum dot weakly coupled to three electrodes. When two electrodes are biased by voltages with opposite polarities, while keeping the third lead (the stem) grounded, the current through the stem is a measure of electron-hole asymmetry of the dot. In this setup we calculate the stem current for both metallic and ferromagnetic (collinearly polarized) leads and discuss how the three-terminal device gives additional information compared to the usual two-terminal setup. We calculate both the sequential and cotunneling contribution for the currents. For the latter part we include a regularization procedure for the cotunneling current, which enables us to also describe the behavior at the charge degeneracy points.Comment: 9 pages, 7 figure

Tobacco smoking and all-cause mortality in a large Australian cohort study: findings from a mature epidemic with current low smoking prevalence

This study finds that up to two-thirds of deaths in current smokers  in Australia can be attributed to smoking. Abstract Background The smoking epidemic in Australia is characterised by historic levels of prolonged smoking, heavy smoking, very high levels of long-term cessation, and low current smoking prevalence, with 13% of adults reporting that they smoked daily in 2013. Large-scale quantitative evidence on the relationship of tobacco smoking to mortality in Australia is not available despite the potential to provide independent international evidence about the contemporary risks of smoking. Methods This is a prospective study of 204,953 individuals aged ≥45 years sampled from the general population of New South Wales, Australia, who joined the 45 and Up Study from 2006–2009, with linked questionnaire, hospitalisation, and mortality data to mid-2012 and with no history of cancer (other than melanoma and non-melanoma skin cancer), heart disease, stroke, or thrombosis. Hazard ratios (described here as relative risks, RRs) for all-cause mortality among current and past smokers compared to never-smokers were estimated, adjusting for age, education, income, region of residence, alcohol, and body mass index. Results Overall, 5,593 deaths accrued during follow-up (874,120 person-years; mean: 4.26 years); 7.7% of participants were current smokers and 34.1% past smokers at baseline. Compared to never-smokers, the adjusted RR (95% CI) of mortality was 2.96 (2.69–3.25) in current smokers and was similar in men (2.82 (2.49–3.19)) and women (3.08 (2.63–3.60)) and according to birth cohort. Mortality RRs increased with increasing smoking intensity, with around two- and four-fold increases in mortality in current smokers of ≤14 (mean 10/day) and ≥25 cigarettes/day, respectively, compared to never-smokers. Among past smokers, mortality diminished gradually with increasing time since cessation and did not differ significantly from never-smokers in those quitting prior to age 45. Current smokers are estimated to die an average of 10 years earlier than non-smokers. Conclusions In Australia, up to two-thirds of deaths in current smokers can be attributed to smoking. Cessation reduces mortality compared with continuing to smoke, with cessation earlier in life resulting in greater reductions

Using pedometers to increase physical activity in overweight and obese women: a pilot study

Background: Most public health guidelines recommend that adults participate in 30 minutes of moderate intensity physical activity on most days of the week. Establishing new ways to achieve these targets in sedentary populations need to be explored. This research evaluated whether the daily use of pedometers could increase physical activity and improve health outcomes in sedentary overweight and obese women. Methods: Twenty six overweight and obese middle-aged women were randomized into two groups: The control group was not able to record their steps daily, whilst the pedometer group, were asked to record the number of steps on a daily basis for 12 weeks. Results: Our data showed that the pedometer group significantly increased their steps/day, by 36%, at the end of the 12 weeks, whereas the control group\u27s physical activity levels remained unchanged. There was no significant difference in weight or body fat composition in the pedometer group compared to the control group. However, there was a significant decrease in systolic blood pressure in the pedometer group (112.8 ± 2.44 mm Hg) compared to the control group (117.3 ± 2.03 mm Hg) (p = 0.003). Conclusion: In conclusion, this pilot study shows that the combination of having step goals and immediate feedback from using a pedometer was effective in increasing physical activity levels in sedentary overweight and obese women