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Search Results: 1 - 10 of 3998 matches for " Johannes Bohacek "
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Distinct molecular components for thalamic- and cortical-dependent plasticity in the lateral amygdala
Osvaldo Mirante,Johannes Bohacek,Isabelle M. Mansuy
Frontiers in Molecular Neuroscience , 2014, DOI: 10.3389/fnmol.2014.00062
Abstract: N-methyl-D-aspartate receptor (NMDAR)-dependent long-term depression (LTD) in the lateral nucleus of the amygdala (LA) is a form of synaptic plasticity thought to be a cellular substrate for the extinction of fear memory. The LA receives converging inputs from the sensory thalamus and neocortex that are weakened following fear extinction. Combining field and patch-clamp electrophysiological recordings in mice, we show that a paired-pulse low-frequency stimulation can induce a robust LTD at thalamic and cortical inputs to LA, and we identify different underlying molecular components at these pathways. We show that while LTD depends on NMDARs and activation of the protein phosphatases PP2B and PP1 at both pathways, it requires NR2B-containing NMDARs at the thalamic pathway, but NR2C/D-containing NMDARs at the cortical pathway. LTD appears to be induced postsynaptically at the thalamic input but presynaptically at the cortical input, since postsynaptic calcium chelation and NMDAR blockade prevent thalamic but not cortical LTD. These results highlight distinct molecular features of LTD in LA that may be relevant for traumatic memory and its erasure, and for pathologies such as post-traumatic stress disorder (PTSD).
Dynamic Modeling of Internet Traffic for Intrusion Detection
Shah Khushboo,Jonckheere Edmond,Bohacek Stephan
EURASIP Journal on Advances in Signal Processing , 2007,
Abstract: Computer network traffic is analyzed via mutual information techniques, implemented using linear and nonlinear canonical correlation analyses, with the specific objective of detecting UDP flooding attacks. NS simulation of HTTP, FTP, and CBR traffic shows that flooding attacks are accompanied by a change of mutual information, either at the link being flooded or at another upstream or downstream link. This observation appears to be topology independent, as the technique is demonstrated on the so-called parking-lot topology, random 50-node topology, and 100-node transit-stub topology. This technique is also employed to detect UDP flooding with low false alarm rate on a backbone link. These results indicate that a change in mutual information provides a useful detection criterion when no other signature of the attack is available.
Dynamic Modeling of Internet Traffic for Intrusion Detection
Khushboo Shah,Edmond Jonckheere,Stephan Bohacek
EURASIP Journal on Advances in Signal Processing , 2007, DOI: 10.1155/2007/90312
Abstract: Computer network traffic is analyzed via mutual information techniques, implemented using linear and nonlinear canonical correlation analyses, with the specific objective of detecting UDP flooding attacks. NS simulation of HTTP, FTP, and CBR traffic shows that flooding attacks are accompanied by a change of mutual information, either at the link being flooded or at another upstream or downstream link. This observation appears to be topology independent, as the technique is demonstrated on the so-called parking-lot topology, random 50-node topology, and 100-node transit-stub topology. This technique is also employed to detect UDP flooding with low false alarm rate on a backbone link. These results indicate that a change in mutual information provides a useful detection criterion when no other signature of the attack is available.
Toll-like receptor 2 deficiency leads to delayed exacerbation of ischemic injury
Bohacek Ivan,Cordeau Pierre,Lalancette–Hébert Mélanie,Gorup Dunja
Journal of Neuroinflammation , 2012, DOI: 10.1186/1742-2094-9-191
Abstract: Background Using a live imaging approach, we have previously shown that microglia activation after stroke is characterized by marked and long-term induction of the Toll-like receptor (TLR) 2 biophotonic signals. However, the role of TLR2 (and potentially other TLRs) beyond the acute innate immune response and as early neuroprotection against ischemic injury is not well understood. Methods TLR2 / mice were subjected to transient middle cerebral artery occlusion followed by different reperfusion times. Analyses assessing microglial activation profile/innate immune response were performed using in situ hybridization, immunohistochemistry analysis, flow cytometry and inflammatory cytokine array. The effects of the TLR2 deficiency on the evolution of ischemic brain injury were analyzed using a cresyl violet staining of brain sections with appropriate lesion size estimation. Results Here we report that TLR2 deficiency markedly affects post-stroke immune response resulting in delayed exacerbation of the ischemic injury. The temporal analysis of the microglia/macrophage activation profiles in TLR2 / mice and age-matched controls revealed reduced microglia/macrophage activation after stroke, reduced capacity of resident microglia to proliferate as well as decreased levels of monocyte chemotactic protein-1 (MCP-1) and consequently lower levels of CD45high/CD11b+ expressing cells as shown by flow cytometry analysis. Importantly, although acute ischemic lesions (24 to 72 h) were smaller in TLR2 / mice, the observed alterations in innate immune response were more pronounced at later time points (at day 7) after initial stroke, which finally resulted in delayed exacerbation of ischemic lesion leading to larger chronic infarctions as compared with wild-type mice. Moreover, our results revealed that TLR2 deficiency is associated with significant decrease in the levels of neurotrophic/anti-apoptotic factor Insulin-like growth factor-1 (IGF-1), expressed by microglia in the areas both in and around ischemic lesion. Conclusion Our results clearly suggest that optimal and timely microglial activation/innate immune response is needed to limit neuronal damage after stroke.
Notification Services for the Server-Based Certificate Validation Protocol  [PDF]
Johannes BUCHMANN, Vangelis KARATSIOLIS
Int'l J. of Communications, Network and System Sciences (IJCNS) , 2009, DOI: 10.4236/ijcns.2009.25042
Abstract: The Server-Based Certificate Validation Protocol allows PKI clients to delegate to a server the construction or validation of certification paths. The protocol’s specification focuses on the communication between the server and the client and its security. It does not discuss how the servers can efficiently locate the necessary PKI resources like certificate or certificate revocation lists. In this paper we concentrate on this topic. We present a simple and effective method to facilitate locating and using various PKI resources by the servers, without modifying the protocol. We use the extension mechanism of the protocol for notifying the servers about PKI repositories, certificates, and revocations. We specify the tasks of the servers and certificate issu-ers and define the messages that are exchanged between them. A proof of concept is given by implementing an SCVP server, a client, and the proposed method in Java.
Mineral and Trace Element Concentrations in Morinda citrifolia L. (Noni) Leaf, Fruit and Fruit Juice  [PDF]
Simla Basar, Johannes Westendorf
Food and Nutrition Sciences (FNS) , 2012, DOI: 10.4236/fns.2012.38155
Abstract: Fruit and leaf of noni (Morinda citrifolia L.) have been used traditionally as food and for medicinal purposes by South Pacific populations since over two thousand years. Recently noni fruit juice became very popular as health beverage worldwide. Manufacturers and distributors of noni juice often praise the high content of minerals and trace elements in conjunction with the geological situation of the origin of the raw noni material. We therefore performed an investigation about the metal concentration of noni fruit, leaf and soil samples from 42 different locations in French Polynesia, and of 16 commercial noni juices. Median concentrations of metals in noni fruit, leaf and fruit juice appeared in a normal range compared to other fruits, however, the variance between different locations was considerable. Noni fruits from lime soil were poorer compared to volcanic soil in most metals. Self-prepared noni juices did generally not serve for more then 10% of the daily requirement of trace elements and minerals per 100 ml. The metal concentration in noni fruit puree was higher compared to clear juice and reached 10% and 34% of the daily requirement in 100 ml for manganese and chromium respectively. The concentrations of toxic metals (As, Cd, Pb) were below 2% of the maximum permitted levels (MPL) in all of these juices. For one of the commercial noni juices the MPL for lead was exceeded (170%) and some others were close to it. Most metals showed a good correlation regarding the concentration in noni fruit versus leaf, but not for soil versus fruit or juice. The concentration of magnesium, manganese, zinc and germanium in the commercial juices was highly correlated to the potassium concentration, indicating that these elements are useful to detect a dilution of noni juices.
Effects of Positive Psychology Interventions in Depressive Patients—A Randomized Control Study  [PDF]
Reinhard Pietrowsky, Johannes Mikutta
Psychology (PSYCH) , 2012, DOI: 10.4236/psych.2012.312158
Abstract: Effects of Positive Psychology (PP) have been shown in several studies to alleviate depressive symptoms in patients suffering from major depression or dysthymia when administered within psychotherapy. The present study served to test for the effects of two interventions from PP (best possible self, three good things) when practised by depressive patients for three weeks without any other concomitant psychotherapy. Seventeen depressive patients were randomly assigned to either the PP group or the control group. Patients in the PP group wrote down the best possible self for one week and then three good things for another two weeks. Patients in the control group wrote down images of the future of mankind for one week and early memories for two weeks. Prior to the intervention and again after it had finished, depressive symptoms, satisfaction with life, positive and negative affect, optimism, and resilience were assessed. While in both groups of patients well-being and resilience increased and depressive symptoms declined, the decline of depressive symptoms and the increase of positive affect and resilience were more pronounced in the PP group. The results support the notion that even a short intervention using PP alone alleviates depressive symptoms and increases well-being. Although the effects were of marginal significance, this may be attributed to the relatively small sample size. Likewise, the use of an Intent-to-Treat analysis may have affected the PP group more than the control group, indicating an underestimation of the potency of PP in the present study.
Higher Education for Complex Real-World Problems and Innovation: A Tribute to Heufler’s Industrial Design Approach  [PDF]
Gerald Steiner, Johannes Scherr
Creative Education (CE) , 2013, DOI: 10.4236/ce.2013.47A2016
Abstract: This article appraises an internationally top ranked higher education program in industrial design, whose stated mission is to enhance students’ ability to deal with complex real-world problems and thereby develop (sustainable) innovation. At the outset, we discuss in general terms—in our view—the indispensable essentials of a higher education program that specifically aims to equip students with the competences needed to successfully deal with such complex real-world problems. In the second part, we specifically examine Heufler’s SchoolofIndustrial DesigninGraz(Austria), its development and characteristics. A summary of general implications for higher education and lessons learnt from this top industrial design program concludes the article. Our analysis suggests that the school’s success is based on a few key cornerstones: 1) The program has a clear mission, which has been communicated early on, internally and externally; 2) Strong leadership, which enables continuity and high-quality output (e.g., attracts high-quality input reflected in the profile of applicants to the program); 3) Real-world projects with co-leadership from industry; 4) Provision of a supportive learning environment which extends beyond lecture times and which is conducive for collaborative creativity; and 5) Faculty are professional experts who focus on problemand project based learning approaches which aim at the joint development of personal, professional domain, systemic, creativity, and sociocultural (collaborative) competence of the students. The authors of this article have been involved with Heufler’sSchoolofIndustrial Designsince its establishment in 1995; they speak on behalf of Gerhard Heufler, the founder and head of this program, who unexpectedly passed away in April 2013. His remarkable leadership has enabled an extraordinary program in higher education with the explicit aim to provide students with competences needed to successfully deal with complex real-world problems.
The Solution of the Eigenvector Problem in Synchrotron Radiation Based Anomalous Small-Angle X-Ray Scattering  [PDF]
Guenter Johannes Goerigk
Advances in Linear Algebra & Matrix Theory (ALAMT) , 2013, DOI: 10.4236/alamt.2013.34012
Abstract: In the last three decades Synchrotron radiation became an indispensable experimental tool for chemical and structural analysis of nano-scaled properties in solid state physics, chemistry, materials science and life science thereby rendering the explanation of the macroscopic behavior of the materials and systems under investigation. Especially the techniques known as Anomalous Small-Angle X-ray Scattering provide deep insight into the materials structural architecture according to the different chemical components on lengths scales starting just above the atomic scale (≈1 nm) up to several 100 nm. The techniques sensitivity to the different chemical components makes use of the energy dependence of the atomic scattering factors, which are different for all chemical elements, thereby disentangling the nanostructure of the different chemical components by the signature of the elemental X-ray absorption edges i.e. by employing synchrotron radiation. The paper wants to focus on the application of an algorithm from linear algebra in the field of synchrotron radiation. It provides a closer look to the algebraic prerequisites, which govern the system of linear equations established by these experimental techniques and its solution by solving the eigenvector problem. The pair correlation functions of the so-called basic scattering functions are expressed as a linear combination of eigenvectors.
Time-Temperature Charge Function of a High Dynamic Thermal Heat Storage with Phase Change Material  [PDF]
Johannes Goeke, Andreas Henne
Energy and Power Engineering (EPE) , 2015, DOI: 10.4236/epe.2015.72004
Abstract: A thermal heat storage system with an energy content of 40 kWh and a temperature of 58°C will be presented. This storage system is suitable for supporting the use of renewable energies in buildings and for absorbing solar heat, heat from co-generation and heat pumps or electric heat from excess wind and solar power. The storage system is equipped with a plate heat exchanger that is so powerful that even with small temperature differences between the flow temperature and the storage temperature a high load dynamic is achieved. The storage system has a performance of 2.8 kW at 4 K and 10.6 kW at a temperature difference of 10 K. Thus, large performance variations in solar thermal systems or CHP plants can be buffered very well. Further a storage charge function Q(T, t) will be presented to characterize the performance of the storage.
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