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Search Results: 1 - 10 of 1456 matches for " Ingmar Schwarz "
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Monte Carlo computer simulations and electron microscopy of colloidal cluster formation via emulsion droplet evaporation
Ingmar Schwarz,Andrea Fortini,Claudia Simone Wagner,Alexander Wittemann,Matthias Schmidt
Physics , 2011, DOI: 10.1063/1.3672106
Abstract: We consider a theoretical model for a binary mixture of colloidal particles and spherical emulsion droplets. The hard sphere colloids interact via additional short-ranged attraction and long-ranged repulsion. The droplet-colloid interaction is an attractive well at the droplet surface, which induces the Pickering effect. The droplet-droplet interaction is a hard-core interaction. The droplets shrink in time, which models the evaporation of the dispersed (oil) phase, and we use Monte Carlo simulations for the dynamics. In the experiments, polystyrene particles were assembled using toluene droplets as templates. The arrangement of the particles on the surface of the droplets was analyzed with cryogenic field emission scanning electron microscopy. Before evaporation of the oil, the particle distribution on the droplet surface was found to be disordered in experiments, and the simulations reproduce this effect. After complete evaporation, ordered colloidal clusters are formed that are stable against thermal fluctuations. Both in the simulations and with field emission scanning electron microscopy, we find stable packings that range from doublets, triplets, and tetrahedra to complex polyhedra of colloids. The simulated cluster structures and size distribution agree well with the experimental results. We also simulate hierarchical assembly in a mixture of tetrahedral clusters and droplets, and find supercluster structures with morphologies that are more complex than those of clusters of single particles.
A Standard System to Study Vertebrate Embryos
Ingmar Werneburg
PLOS ONE , 2009, DOI: 10.1371/journal.pone.0005887
Abstract: Staged embryonic series are important as reference for different kinds of biological studies. I summarise problems that occur when using ‘staging tables’ of ‘model organisms’. Investigations of developmental processes in a broad scope of taxa are becoming commonplace. Beginning in the 1990s, methods were developed to quantify and analyse developmental events in a phylogenetic framework. The algorithms associated with these methods are still under development, mainly due to difficulties of using non-independent characters. Nevertheless, the principle of comparing clearly defined newly occurring morphological features in development (events) in quantifying analyses was a key innovation for comparative embryonic research. Up to date no standard was set for how to define such events in a comparative approach. As a case study I compared the external development of 23 land vertebrate species with a focus on turtles, mainly based on reference staging tables. I excluded all the characters that are only identical for a particular species or general features that were only analysed in a few species. Based on these comparisons I defined 104 developmental characters that are common either for all vertebrates (61 characters), gnathostomes (26), tetrapods (3), amniotes (7), or only for sauropsids (7). Characters concern the neural tube, somite, ear, eye, limb, maxillary and mandibular process, pharyngeal arch, eyelid or carapace development. I present an illustrated guide listing all the defined events. This guide can be used for describing developmental series of any vertebrate species or for documenting specimen variability of a particular species. The guide incorporates drawings and photographs as well as consideration of species identifying developmental features such as colouration. The simple character-code of the guide is extendable to further characters pertaining to external and internal morphological, physiological, genetic or molecular development, and also for other vertebrate groups not examined here, such as Chondrichthyes or Actinopterygii. An online database to type in developmental events for different stages and species could be a basis for further studies in comparative embryology. By documenting developmental events with the standard code, sequence heterochrony studies (i.e. Parsimov) and studies on variability can use this broad comparative data set.
Common Factors between Swedish and Chinese Entrepreneurial Leadership Styles
Ingmar Bremer
Business Intelligence Journal , 2009,
Abstract: This paper includes a comparative study of the entrepreneurial leadership of both Sweden and China, taking into consideration such factors as their political and economic history, leadership styles, and regulatory changes. It will conclude with an analysis of the factors that both entrepreneur leadership styles have in common, as well as substantial differences between fundamental approaches to business development.
Morphology of the suspensorial, jaw, and opercle musculature of Beloniformes and related species (Teleostei: Acanthopterygii), with a special reference to the m. adductor mandibulae complex
Ingmar Werneburg
PeerJ , 2015, DOI: 10.7287/peerj.preprints.691v1
Abstract: The taxon Beloniformes represents a heterogeneous group of teleost fishes that show an extraordinary diversity of jaw morphology. I present new anatomical descriptions of the jaw musculature in six selected beloniforms and four closely related species. A reduction of the external jaw adductor (A1) and a changed morphology of the intramandibular musculature were found in many Beloniformes. This might be correlated with the progressively reduced mobility of the upper and lower jaw bones. The needlefishes and sauries, which are characterised by extremely elongated and stiffened jaws, show several derived characters, which in combination enable the capture of fish at high velocity. The ricefishes are characterised by several derived and many plesiomorphic characters that make broad scale comparisons difficult. Soft tissue characters are highly diverse among hemiramphids and flying fishes reflecting the uncertainty about their phylogenetic position and interrelationship. The morphological findings presented herein may help to interpret future phylogenetic analyses using cranial musculature in Beloniformes.
A Bayesian Model of node interaction in networks
Ingmar Schuster
Computer Science , 2014,
Abstract: We are concerned with modeling the strength of links in networks by taking into account how often those links are used. Link usage is a strong indicator of how closely two nodes are related, but existing network models in Bayesian Statistics and Machine Learning are able to predict only wether a link exists at all. As priors for latent attributes of network nodes we explore the Chinese Restaurant Process (CRP) and a multivariate Gaussian with fixed dimensionality. The model is applied to a social network dataset and a word coocurrence dataset.
Consistency of Importance Sampling estimates based on dependent sample sets and an application to models with factorizing likelihoods
Ingmar Schuster
Statistics , 2015,
Abstract: In this paper, I proof that Importance Sampling estimates based on dependent sample sets are consistent under certain conditions. This can be used to reduce variance in Bayesian Models with factorizing likelihoods, using sample sets that are much larger than the number of likelihood evaluations, a technique dubbed Sample Inflation. I evaluate Sample Inflation on a toy Gaussian problem and two Mixture Models.
Gradient Importance Sampling
Ingmar Schuster
Statistics , 2015,
Abstract: Adaptive Monte Carlo schemes developed over the last years usually seek to ensure ergodicity of the sampling process in line with MCMC tradition. This poses constraints on what is possible in terms of adaptation. In the general case ergodicity can only be guaranteed if adaptation is diminished at a certain rate. Importance Sampling approaches offer a way to circumvent this limitation and design sampling algorithms that keep adapting. Here I present a gradient informed variant of SMC (and its special case Population Monte Carlo) for static problems.
DAS2-Theory of Personality: A Cognitive Approach to the Enneagram  [PDF]
Erik Schwarz, Shayesteh Zarrabi
Psychology (PSYCH) , 2017, DOI: 10.4236/psych.2017.811118
Abstract: The Enneagram is a typology of personality that scopes at the level of ego-personality. Despite the vast amount of attention, it has accumulated since its modern emergence in the 20th century from the Sufi tradition, it is still in need of grounding into current scientific work to disperse some of its much criticized mystical language. The DAS2-theory aims at reconstructing the Enneagram based on cognitive concepts by first establishing the Dynamic Social Field Theory (DSoFT) that expands the Bourdieusian concept of social fields (Bourdieu, 1984), and then proposing the ethological trilogy of Dominance, Aversion, Submission (the DAS-triad)—three distinct stances towards power that have evolved under the pressure of violence, as described by Lorenz (1998). DSoFT posits that the mind is constantly challenged to find the social field that most appeals to the ego in order to react to people and events. To this end—described by using the Buddhist concept of Monkey Mind—the mind jumps from scenario to scenario (field to field) creating micro-contests until it finds a proper reframing of the challenge where it can have a strategy that appeals to the ego. To understand how a DAS-type is formed, three iterative levels have to be built. At the bottom is the DAS-triad, or stances. Because each stance can be applied from a position of superiority or inferiority—that the mind evaluates from the field’s rules—, each of the three stances can branch into two styles, yielding six potential DAS-styles. DAS-styles explain behaviors clearly, distinctly, and ethologically, and form the basis for the application of the DAS2-theory. Lastly, a DAS-type is the selection of a style from the superior triad, as well as one from the inferior triad. Therefore nine types are possible, which correspond to the nine Enneatypes. The DAS2-theory typology can be applied to interpret not only the individuals but also the supra-individual entities’ behaviors without having to resort to metaphors that vaguely describe intentions and actions. It offers new innovative ways to analyze political events, power scenarios, market perception of brands, and other social dynamics, and can greatly influence the academic or social communities of the Enneagram and Power Studies. Further developments in neuropsychoendocrinology and other fields may prove the DAS2-theory assumptions.
Does Multimorbidity Influence the Occurrence Rates of Chronic Conditions? A Claims Data Based Comparison of Expected and Observed Prevalence Rates
Ingmar Sch?fer
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0045390
Abstract: Objective Multimorbidity is a complex phenomenon with an almost endless number of possible disease combinations with unclear implications. One important aspect in analyzing the clustering of diseases is to distinguish between random coexistence and statistical dependency. We developed a model to account for random coexistence based on stochastic distribution. We analyzed if the number of diseases of the patients influences the occurrence rates of chronic conditions. Methods We analyzed claims data of 121,389 persons aged 65+ using a list of 46 chronic conditions. Expected prevalences were simulated by drawing without replacement from all observed diseases using observed overall prevalences as initial probability weights. To determine if a disease occurs more or less frequently than expected by chance we calculated observed-minus-expected deltas for each disease. We defined clinical relevance as |delta| ≥ 5.0%. 18 conditions were excluded because of a prevalence < 5.0%. Results We found that (1) two chronic conditions (e.g. hypertension) were more frequent than expected in patients with a low number of comorbidities; (2) four conditions (e.g. renal insufficiency) were more frequent in patients with many comorbidities; (3) six conditions (e.g. cancer) were less frequent with many comorbidities; and (4) 16 conditions had an average course of prevalences. Conclusion A growing extent of multimorbidity goes along with a rapid growth of prevalences. This is for the largest part merely a stochastic effect. If we account for this effect we find that only few diseases deviate from the expected prevalence curves. Causes for these deviations are discussed. Our approach also has methodological implications: Naive analyses of multimorbidity might easily be affected by bias, because the prevalence of all chronic conditions necessarily increases with a growing extent of multimorbidity. We should therefore always examine and discuss the stochastic interrelations between the chronic conditions we analyze.
Selection criteria for cytoreductive surgery and hyperthermic intraperitoneal chemotherapy in gastric cancer
Ingmar K?nigsrainer
World Journal of Gastroenterology , 2011, DOI: 10.3748/wjg.v17.i37.4153
Abstract: Peritoneal carcinomatosis in gastric cancer is associated with a dismal prognosis. Systemic chemotherapy is not effective because of the existence of a blood-peritoneal barrier. Cytoreductive surgery and intraperitoneal chemotherapy can improve survival and quality of life in selected patients. Patient selection for this multimodal approach is one of the most critical issues, and calls for interdisciplinary evaluation by radiologists, medical and surgical oncologists, and anaesthetists. This article sets forth criteria for selection of gastric cancer patients suffering from peritoneal carcinomatosis.
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