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Search Results: 1 - 10 of 146259 matches for " Markus Küper "
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Transumbilical single-incision laparoscopic inguinal hernia repair – feasibility study on anatomical specimens
Andreas Kirschniak,Thomas Shiozawa,Markus Küper,Frank A. Granderath
Videosurgery and Other Miniinvasive Techniques , 2010,
Abstract: Laparoscopic inguinal hernia has replaced open surgery in recent years. For transabdominal preperitoneal mesh placement,3 incisions have to be made to prepare the inguinal region, place the mesh and adapt the peritoneum witha suture. We describe the feasibility of a single incision transumbilical hernia repair. For this, we operated on3 anatomical specimens (2 male, 1 female), which had been conserved using alcohol-glycerol fixation. A subumbilical1.5 cm incision was performed, and three 5 mm trocars were inserted. The preparation and procedure steps conformedto conventional laparoscopic transabdominal preperitoneal hernia repair (TAPP). In the right port we used a 5 mm30 degree laparoscope, for preparation a grasper and scissors with optional flexure. Mean procedure time was 45.5 min(35-55 min, ±7 min). The left and right inguinal region was prepared. Adaptation in handling and ergonomics needsfamiliarization.
Faster Black-Box Algorithms Through Higher Arity Operators
Benjamin Doerr,Daniel Johannsen,Timo K?tzing,Per Kristian Lehre,Markus Wagner,Carola Winzen
Computer Science , 2010,
Abstract: We extend the work of Lehre and Witt (GECCO 2010) on the unbiased black-box model by considering higher arity variation operators. In particular, we show that already for binary operators the black-box complexity of \leadingones drops from $\Theta(n^2)$ for unary operators to $O(n \log n)$. For \onemax, the $\Omega(n \log n)$ unary black-box complexity drops to O(n) in the binary case. For $k$-ary operators, $k \leq n$, the \onemax-complexity further decreases to $O(n/\log k)$.
Inference for Multi-Dimensional High-Frequency Data: Equivalence of Methods, Central Limit Theorems, and an Application to Conditional Independence Testing
Markus Bibinger,Per A. Mykland
Statistics , 2013,
Abstract: We find the asymptotic distribution of the multi-dimensional multi-scale and kernel estimators for high-frequency financial data with microstructure. Sampling times are allowed to be asynchronous and endogenous. In the process, we show that the classes of multi-scale and kernel estimators for smoothing noise perturbation are asymptotically equivalent in the sense of having the same asymptotic distribution for corresponding kernel and weight functions. The theory leads to multi-dimensional stable central limit theorems and feasible versions. Hence they allow to draw statistical inference for a broad class of multivariate models which paves the way to tests and confidence intervals in risk measurement for arbitrary portfolios composed of high-frequently observed assets. As an application, we enhance the approach to construct a test for investigating hypotheses that correlated assets are independent conditional on a common factor.
Cardiac output in idiopathic normal pressure hydrocephalus: association with arterial blood pressure and intracranial pressure wave amplitudes and outcome of shunt surgery
Per K Eide
Fluids and Barriers of the CNS , 2011, DOI: 10.1186/2045-8118-8-11
Abstract: Prospective iNPH patients (29) were clinically graded using an NPH grading scale. Continuous overnight minimally-invasive monitoring of CO and ABP was done simultaneously with ICP monitoring; the CO, ABP, and ICP parameters were parsed into 6-second time windows. Patients were assessed for shunt surgery on clinical grade, Evan's index, and ICP wave amplitude. Follow-up clinical grading was performed 12 months after surgery.ICP wave amplitudes but not CO or ABP wave amplitude, showed good correlation with the response to shunt treatment. The patients with high ICP wave amplitude did not have accompanying high levels of CO or ABP wave amplitude. Correlation analysis between CO and ICP wave amplitudes in individual patients showed different profiles [significantly positive in 10 (35%) and significantly negative in 16 (55%) of 29 recordings]. This depended on whether there was also a correlation between ABP and ICP wave amplitudes and on the average level of ICP wave amplitude.These results gave no evidence that the increased levels of ICP wave amplitudes seen in iNPH shunt responders prior to surgery were accompanied by elevated levels of ABP wave amplitudes or elevated CO. In the individual patients the correlation between CO and ICP wave amplitude was partly related to an association between ABP and ICP wave amplitudes which can be indicative of the state of cerebrovascular pressure regulation, and partly related to the ICP wave amplitude which can be indicative of the intracranial compliance.The clinical condition idiopathic normal pressure hydrocephalus (iNPH) consists of unsteady gait, urinary incontinence, dementia, and enlarged lateral ventricles [1]. The preferred treatment is insertion of a shunt for drainage of cerebrospinal fluid (CSF), which gives good clinical results and a favourable complication profile [2,3]. Despite recent advances in the treatment of iNPH, the rationale for treatment is based on a limited understanding of its pathophysiology. Possible
Cerebrospinal fluid pulse pressure amplitude during lumbar infusion in idiopathic normal pressure hydrocephalus can predict response to shunting
Per K Eide, Are Brean
Fluids and Barriers of the CNS , 2010, DOI: 10.1186/1743-8454-7-5
Abstract: The study population consisted of all iNPH patients undergoing both diagnostic lumbar infusion testing and continuous over-night ICP monitoring during the period 2002-2007. The severity of iNPH was assessed using our NPH grading scale before surgery and 12 months after shunting. The CSFP pulse was characterized from the amplitude of single pressure waves.Totally 62 iNPH patients were included, 45 of them underwent shunt surgery, in whom 78% were shunt responders. Among the 45 shunted patients, resistance to CSF outflow (Rout) was elevated (≥ 12 mmHg/ml/min) in 44. The ICP pulse amplitude recorded over-night was elevated (i.e. mean ICP wave amplitude ≥ 4 mmHg) in 68% of patients; 92% of these were shunt responders. In those with elevated overnight ICP pulse amplitude, we found also elevated CSFP pulse amplitude recorded during lumbar infusion testing, both during the opening phase following lumbar puncture and during a standardized period of lumbar infusion (15 ml Ringer over 10 min). The clinical response to shunting after 1 year strongly associated with the over-night ICP pulse amplitude, and also with the pulsatile CSFP during the period of lumbar infusion. Elevated CSFP pulse amplitude during lumbar infusion thus predicted shunt response with sensitivity of 88 and specificity of 60 (positive and negative predictive values of 89 and 60, respectively).In iNPH patients, shunt response can be anticipated in 9/10 patients with elevated overnight ICP pulse amplitude, while in only 1/10 with low ICP pulse amplitude. Additionally, the CSFP pulse amplitude during lumbar infusion testing was elevated in patients with elevated over-night ICP pulse amplitude. In particular, measurement of CSFP pulse amplitude during a standardized infusion of 15 ml Ringer over 10 min was useful in predicting response to shunt surgery and can be used as a screening procedure for selection of iNPH patients for shunting.The clinical condition normal pressure hydrocephalus (NPH) incorporates gai
Species-Area Relationships Are Controlled by Species Traits
Markus Franzén, Oliver Schweiger, Per-Eric Betzholtz
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0037359
Abstract: The species-area relationship (SAR) is one of the most thoroughly investigated empirical relationships in ecology. Two theories have been proposed to explain SARs: classical island biogeography theory and niche theory. Classical island biogeography theory considers the processes of persistence, extinction, and colonization, whereas niche theory focuses on species requirements, such as habitat and resource use. Recent studies have called for the unification of these two theories to better explain the underlying mechanisms that generates SARs. In this context, species traits that can be related to each theory seem promising. Here we analyzed the SARs of butterfly and moth assemblages on islands differing in size and isolation. We tested whether species traits modify the SAR and the response to isolation. In addition to the expected overall effects on the area, traits related to each of the two theories increased the model fit, from 69% up to 90%. Steeper slopes have been shown to have a particularly higher sensitivity to area, which was indicated by species with restricted range (slope = 0.82), narrow dietary niche (slope = 0.59), low abundance (slope = 0.52), and low reproductive potential (slope = 0.51). We concluded that considering species traits by analyzing SARs yields considerable potential for unifying island biogeography theory and niche theory, and that the systematic and predictable effects observed when considering traits can help to guide conservation and management actions.
Heritability and Genetic Correlations of Fear-Related Behaviour in Red Junglefowl–Possible Implications for Early Domestication
Beatrix Agnvall, Markus J?ngren, Erling Strandberg, Per Jensen
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0035162
Abstract: Domesticated species differ from their wild ancestors in a number of traits, generally referred to as the domesticated phenotype. Reduced fear of humans is assumed to have been an early prerequisite for the successful domestication of virtually all species. We hypothesized that fear of humans is linked to other domestication related traits. For three generations, we selected Red Junglefowl (ancestors of domestic chickens) solely on the reaction in a standardized Fear of Human-test. In this, the birds were exposed for a gradually approaching human, and their behaviour was continuously scored. This generated three groups of animals, high (H), low (L) and intermediate (I) fearful birds. The birds in each generation were additionally tested in a battery of behaviour tests, measuring aspects of fearfulness, exploration, and sociality. The results demonstrate that the variation in fear response of Red Junglefowl towards humans has a significant genetic component and is genetically correlated to behavioural responses in other contexts, of which some are associated with fearfulness and others with exploration. Hence, selection of Red Junglefowl on low fear for humans can be expected to lead to a correlated change of other behavioural traits over generations. It is therefore likely that domestication may have caused an initial suite of behavioural modifications, even without selection on anything besides tameness.
The baseline pressure of intracranial pressure (ICP) sensors can be altered by electrostatic discharges
Per K Eide, André Bakken
BioMedical Engineering OnLine , 2011, DOI: 10.1186/1475-925x-10-75
Abstract: We performed bench-testing of a set of commercial ICP sensors. In our experimental setup, the ICP sensor was placed in a container with 0.9% NaCl solution. A test person was charged 0.5 - 10 kV, and then delivered ESD's to the sensor by touching a metal rod that was located in the container. The continuous pressure signals were recorded continuously before/after the ESD's, and the pressure readings were stored digitally using a computerized systemA total of 57 sensors were tested, including 25 Codman ICP sensors and 32 Raumedic sensors. When charging the test person in the range 0.5-10 kV, typically ESD's in the range 0.5 - 5 kV peak pulse were delivered to the ICP sensor. Alterations in baseline pressure ≥ 2 mmHg was seen in 24 of 25 (96%) Codman sensors and in 17 of 32 (53%) Raumedic sensors. Lasting changes in baseline pressure > 10 mmHg that in the clinical setting would affect patient management, were seen frequently for both sensor types. The changes in baseline pressure were either characterized by sudden shifts or gradual drifts in baseline pressure.The baseline pressures of commercial solid ICP sensors can be altered by ESD's at discharge magnitudes that are clinically relevant. Shifts in baseline pressure change the ICP levels visualised to the physician on the monitor screen, and thereby reveal wrong ICP values, which likely represent a severe risk to the patient.In patients with brain injury due to traumatic brain injury, stroke, or complications to neurosurgery, the continuous monitoring of intracranial pressure (ICP) is crucial for surveillance [1-3], even though no randomized trials have confirmed the benefit of ICP monitoring in patients with brain injury [4].Modern ICP monitoring was first introduced by Janny in 1950 [5] and Lundberg in 1960 [6]. While ICP initially was mostly measured from fluid-filled catheters in connection with the ventricular cerebrospinal fluid (CSF), the first ICP micro transducers were introduced in the 1980's [7,8]. The ICP
The categorical theory of relations and quantizations
Per K. Jakobsen,Valentin Lychagin
Mathematics , 2001,
Abstract: In this paper we develope a categorical theory of relations and use this formulation to define the notion of quantization for relations. Categories of relations are defined in the context of symmetric monoidal categories. They are shown to be symmetric monoidal categories in their own right and are found to be isomorphic to certain categories of $A-A$ bicomodules. Properties of relations are defined in terms of the symmetric monoidal structure. Equivalence relations are shown to be commutative monoids in the category of relations. Quantization in our view is a property of functors between monoidal categories. This notion of quantization induce a deformation of all algebraic structures in the category, in particular the ones defining properties of relations like transitivity and symmetry.
Reduction of Native Diversity by Invasive Plants Depends on Habitat Conditions  [PDF]
Yvonne Künzi, Daniel Prati, Markus Fischer, Steffen Boch
American Journal of Plant Sciences (AJPS) , 2015, DOI: 10.4236/ajps.2015.617273
Abstract: Invasions by exotic plant species and their impacts on invaded communities are a highly topical field of research because it provides a basis for the management of neophyte populations. However, for many invasive neophyte species in Central Europe little is known about their impacts on invaded plant communities. Moreover, it has hardly been considered whether effects vary among habitat conditions. Here, we selected each ten sites with different habitat conditions invaded by Erigeron annuus, Fallopia japonica, Impatiens glandulifera and Solidago canadensis which were listed as invasive in Switzerland. At each site, we established four 4 m × 1 m subplots covering a gradient from very low to very high cover of the particular neophyte species to investigate the effect of increasing neophyte cover on the species richness, Shannon diversity and evenness of the invaded plant communities. Moreover, we measured soil pH and characterized habitat conditions using Ellenberg indicator values to light and soil fertility. Whereas increasing cover of I. glandulifera had no effect on the diversity of invaded plant communities, an increasing cover of E. annuus negatively affected Shannon diversity. An increasing cover of F. japonica combined with a decreasing soil pH negatively affected the Shannon diversity of invaded plant communities. Similarly, an increasing cover of S. canadensis in combination with decreasing soil fertility negatively affected the Shannon diversity and evenness of invaded communities. Our results indicate that significant effects of increasing neophyte cover are mostly coupled to particular habitat conditions and then rather suppress than eliminate native plant species in invaded communities. We therefore suggest including abiotic variables in further impact studies on biotic invasions. Furthermore, adapting measures to the respective environmental context can be a useful tool in priority setting for the management of invasive neophyte populations and the restoration of invaded habitats.
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