38 research outputs found
Trust in Management under Post-bureaucratic Conditions: The Case of Finnish Civil Servants
The Finnish state administration has recently undergone a wave of reformstowards decentralized decision-making and increased flexibility in organizing work.Traditional bureaucracy, however, has its virtues. Based on a survey and qualitativeinterview material, the results presented in this paper indicate that many characteristicsof bureaucracy, such as well-defined work roles and hierarchical control, facilitate trustamong employees. In contrast, the current post-bureaucratic model of organizing workmay increase insecurity and decrease trust
Kolmio- ja ramppiaallot kohteen havaitsemisessa taajuusmoduloidulla kantoaaltotutkalla
The goal of this thesis was to study how a triangular chirp can be used in target detection and parameter estimation with an FMCW radar. The history of radar technology is briefly discussed, and motivation for the research is presented with a review of some FMCW radar applications. The triangular chirp is compared with slow-time processed ramp chirps on a theoretical basis. A method of improving the accuracy of triangular chirps with zero padding is presented. The process of zero padding is demonstrated with a MATLAB example, and then applied to real measurement data.
The measurements were performed in an anechoic chamber and an office environment. Range and radial velocity of a single target were considered. A walking person was used as the test target. A highly accurate laser sensor was used as a reference.
The results demonstrate that the accuracy of a triangular chirp can be greatly improved with zero padding, which allows much shorter chirps to be used while maintaining a high accuracy. For example, a zero padded 1000 μs long triangular chirp was used to determine the radial velocity of a walking target with an accuracy of approximately 0.25 m/s. In comparison, without zero padding the accuracy was approximately 2 m/s. To reach a comparable accuracy without zero padding, the triangular chirp would have to be significantly longer. At the end of the thesis, topics for further research are proposed.Työssä tutkitaan, kuinka kolmioaaltoa voidaan käyttää havaitun kohteen paikan ja nopeuden määrittämiseen FMCW-tutkalla. Käsittelen alussa lyhyesti tutkien historiaa, ja FMCW-tutkien yleisiä sovelluksia. Kolmioaaltoa verrataan ramppiaaltoon teoreettiselta pohjalta. Esittelen työssä menetelmän kolmioaallon mittaustarkkuuden parantamiseksi lisäämällä näytteistettyyn signaaliin nollia. Menetelmää demonstroidaan MATLAB:illa ja lopulta sovelletaan mitattuun dataan.
Mittaukset suoritettiin radiokaiuttomassa huoneessa ja toimistotilassa. Tilaisuuksissa pyrittiin mittaamaan yksittäisen kohteen sijaintia ja liikenopeutta. Mittauskohteena toimi kävelevä ihminen. Mittausten vertailukohteena toimi lasersensori.
Saadut tulokset demonstroivat kolmioaallon tarkkuuden olevan merkittävästi parannettavissa esitetyllä menetelmällä. Korkean tarkkuuden säilyttäminen on mahdollista lyhyelläkin kolmioaallolla, joka ilman nollien lisäämistä olisi erittäin epätarkka. Esimerkiksi kävelevän kohteen nopeus mitattiin 1000 μs pituisella kolmioaallolla ja nollien lisäämisellä noin 0.25 m/s tarkkuudella, kun taas ilman nollia tarkkuus oli noin 2 m/s. Ilman nollien lisäystä kolmioaallon pituuden olisi oltava moninkertainen vastaavan tarkkuuden saavuttamiseksi. Työn lopussa esitetään aiheita jatkotutkimukselle
Ray-Optics Simulations of Outdoor-to-Indoor Multipath Channels at 4 and 14 GHz
Radio wave propagation simulations based on the ray-optical approximation
have been widely adopted in coverage analysis for a range of situations,
including the outdoor-to-indoor (O2I) scenario. In this work we present O2I
ray-tracer simulations utilizing a complete building floor plan in the form of
a point cloud. The ray-tracing simulation results are compared to measured
channels at 4 and 14 GHz in terms of large scale parameters, namely path loss,
delay spread and angular spread. In this work we address the importance of 1)
interior walls and propagation paths originating therein, and 2) site-specific
knowledge of window structure in accurately reproducing the O2I channel,
particularly the presence of a thin insulating metal film on the windows. The
best agreement between measurements and simulations was observed for the most
detailed simulation. For both frequencies a mean error of less than 1.5 dB is
reached for path loss, and a relative error of less than 10% for delay and
angular spreads. Not including the metal film in simulations increases error of
estimated building entry loss considerably, whereas absence of interior walls
is detrimental to reproduction of large scale parameters
Managerial Perspective on Open Source Collaboration and Networked Innovation
This study explores the managerial perspectives towards open source software and networked innovation. We analysed six software companies who use open source software as a significant part of their product or service offering. The study found notable differences in managerial attitudes, expected benefits and key challenges related to open source software and its role in innovative activities. While all companies were using same pieces of software with open source communities, there were different levels of engagement in the development of the software and information flows between companies and communities. A deeper level of involvement enables the exchange of more than just the code: like ideas, influences, opinions and even innovations or parts of them. The differences in managerial views on open source and networked innovation may be explained by industry domains, value chain position and leadership styl
Regulation of excitation-contraction coupling in mouse cardiac myocytes: integrative analysis with mathematical modelling
<p>Abstract</p> <p>Background</p> <p>The cardiomyocyte is a prime example of inherently complex biological system with inter- and cross-connected feedback loops in signalling, forming the basic properties of intracellular homeostasis. Functional properties of cells and tissues have been studied e.g. with powerful tools of genetic engineering, combined with extensive experimentation. While this approach provides accurate information about the physiology at the endpoint, complementary methods, such as mathematical modelling, can provide more detailed information about the processes that have lead to the endpoint phenotype.</p> <p>Results</p> <p>In order to gain novel mechanistic information of the excitation-contraction coupling in normal myocytes and to analyze sophisticated genetically engineered heart models, we have built a mathematical model of a mouse ventricular myocyte. In addition to the fundamental components of membrane excitation, calcium signalling and contraction, our integrated model includes the calcium-calmodulin-dependent enzyme cascade and the regulation it imposes on the proteins involved in excitation-contraction coupling. With the model, we investigate the effects of three genetic modifications that interfere with calcium signalling: 1) ablation of phospholamban, 2) disruption of the regulation of L-type calcium channels by calcium-calmodulin-dependent kinase II (CaMK) and 3) overexpression of CaMK. We show that the key features of the experimental phenotypes involve physiological compensatory and autoregulatory mechanisms that bring the system to a state closer to the original wild-type phenotype in all transgenic models. A drastic phenotype was found when the genetic modification disrupts the regulatory signalling system itself, i.e. the CaMK overexpression model.</p> <p>Conclusion</p> <p>The novel features of the presented cardiomyocyte model enable accurate description of excitation-contraction coupling. The model is thus an applicable tool for further studies of both normal and defective cellular physiology. We propose that integrative modelling as in the present work is a valuable complement to experiments in understanding the causality within complex biological systems such as cardiac myocytes.</p
Simulation-Based Study of Control Strategies for Beating of Human Cardiomyocyte Cultures
Peer reviewe
Vascular Endothelial Growth Factor-B Induces a Distinct Electrophysiological Phenotype in Mouse Heart
Vascular endothelial growth factor B (VEGF-B) is a potentmediator of vascular, metabolic, growth, and stress responses in the heart, but the effects on cardiac muscle and cardiomyocyte function are not known. The purpose of this study was to assess the effects of VEGF-B on the energy metabolism, contractile, and electrophysiological properties of mouse cardiac muscle and cardiac muscle cells. In vivo and ex vivo analysis of cardiac-specific VEGF-B TG mice indicated that the contractile function of the TG hearts was normal. Neither the oxidative metabolism of isolated TG cardiomyocytes nor their energy substrate preference showed any difference to WT cardiomyocytes. Similarly, myocyte Ca2+ signaling showed only minor changes compared to WT myocytes. However, VEGF-B overexpression induced a distinct electrophysiological phenotype characterized by ECG changes such as an increase in QRSp time and decreases in S and R amplitudes. At the level of isolated TG cardiomyocytes, these changes were accompanied with decreased action potential upstroke velocity and increased duration (APD60-70). These changes were partly caused by downregulation of sodium current (INa) due to reduced expression of Nav1.5. Furthermore, TG myocytes had alterations in voltage-gated K + currents, namely decreased density of transient outward current (Ito) and total K + current (Ipeak). At the level of transcription, these were accompanied by downregulation of Kv channel-interacting protein 2 (Kcnip2), a knownmodulatory subunit for Kv4.2/3 channel. Cardiac VEGF-B overexpression induces a distinct electrophysiological phenotype including remodeling of cardiomyocyte ion currents, which in turn induce changes in action potential waveform and ECG.Peer reviewe
Impact of Sarcoplasmic Reticulum Calcium Release on Calcium Dynamics and Action Potential Morphology in Human Atrial Myocytes: A Computational Study
Electrophysiological studies of the human heart face the fundamental challenge that experimental data can be acquired only from patients with underlying heart disease. Regarding human atria, there exist sizable gaps in the understanding of the functional role of cellular Ca2+ dynamics, which differ crucially from that of ventricular cells, in the modulation of excitation-contraction coupling. Accordingly, the objective of this study was to develop a mathematical model of the human atrial myocyte that, in addition to the sarcolemmal (SL) ion currents, accounts for the heterogeneity of intracellular Ca2+ dynamics emerging from a structurally detailed sarcoplasmic reticulum (SR). Based on the simulation results, our model convincingly reproduces the principal characteristics of Ca2+ dynamics: 1) the biphasic increment during the upstroke of the Ca2+ transient resulting from the delay between the peripheral and central SR Ca2+ release, and 2) the relative contribution of SL Ca2+ current and SR Ca2+ release to the Ca2+ transient. In line with experimental findings, the model also replicates the strong impact of intracellular Ca2+ dynamics on the shape of the action potential. The simulation results suggest that the peripheral SR Ca2+ release sites define the interface between Ca2+ and AP, whereas the central release sites are important for the fire-diffuse-fire propagation of Ca2+ diffusion. Furthermore, our analysis predicts that the modulation of the action potential duration due to increasing heart rate is largely mediated by changes in the intracellular Na+ concentration. Finally, the results indicate that the SR Ca2+ release is a strong modulator of AP duration and, consequently, myocyte refractoriness/excitability. We conclude that the developed model is robust and reproduces many fundamental aspects of the tight coupling between SL ion currents and intracellular Ca2+ signaling. Thus, the model provides a useful framework for future studies of excitation-contraction coupling in human atrial myocytes
Tuntemattoman antennin karakterisointi rakennetta rikkomattomilla menetelmillä saatuun dataan perustuen
The Paradox of Post-Bureaucracy: Trust Formation among State Administration Employees in Finland
This paper discusses civil servants’ trust in management under conditions of organizational change. The paper draws on asurvey and qualitative interview material collected from five knowledge-intensive public sector organizations in Finland. Theresults indicate that the post-bureaucratic model of organizing work in Finnish state administration may increase insecurityand decrease trust among employees. The paper serves as a reminder that all organizational models have their costs and benefits.Traditional bureaucracy fosters predictability and longevity in employee relations. In this respect, the post-bureaucratic model oforganizing work may not always be as effective in generating trust as traditional bureaucracy is