235 research outputs found
The Correlation Between Treasury Securities and the Stock Market: A Study of Explanatory Variables
The purpose of the thesis is to retrieve the correlation between treasury securities of different maturities and the stock market and find significant variables to explain this relationship. Correlation time series were retrieved and used as dependent variables in a multivariate regression in order to find significant explanatory variables. The theory includes prior research done on the relationship between the stock market and treasury securities. Further the stock market and treasury securities are studied in detail. The highest explanatory power for the model was found for the 10 year note and stock market correlation. Significant variables of main importance were the volume traded, federal funds rate return and the business cycle. Support for the flight into quality theory was retrieved, as well as evidence of the importance for variables based on macroeconomic factors for the three correlation series
Motion Control of Hexapod Robot Using Model-Based Design
Six-legged robots, also referred to as hexapods, can have very complex locomotion patterns and provide the means of moving on terrain where wheeled robots might fail. This thesis demonstrates the approach of using Model-Based Design to create control of such a hexapod. The project comprises the whole range from choosing of hardware, creating CAD models, development in MATLAB/Simulink and code generation. By having a computer model of the robot, development of locomotion patterns can be done in a virtual environment before tested on the hardware. Leg movement is implemented as algorithms to determine leg movement order, swing trajectories, body height alteration and balancing. Feedback from the environment is implemented as a internal measurement unit that measures body angles using sensor fusion. The thesis has resulted in successful creation of a hexapod platform for locomotion development through Model-Based Design. Both a virtual hexapod in Sim-Mechanics and a hardware hexapod is created and code generation to the hardware from the development environment is fully supported. Results include successful implementation of hexapod movement and the walking algorithm has the ability to walk on a flat surface, rotate and alter the body height. Implementation also contains a successful balancing mode for the hexapod whereas it is able to keep the main body level while the floor angle is altered
The role of BECCS in providing negative emissions in Sweden under competing interests for forest-based biomass
Negative emissions are needed to meet climate mitigation targets and can be achieved through the capture and storage of biogenic CO2 emissions (BECCS). Sweden holds a large potential for BECCS from the industry and heat and power sectors. This work provides a first assessment of how the conditions for BECCS in Sweden are impacted by competition for forest-based biomass from other sectors, in this work represented by production of transportation fuels. An optimization model is applied to study how demand levels for negative emissions and biofuels, and availability of forestry resources, influence the optimal system design considering the electricity, district heating and biomass sectors. BECCS and direct air capture technologies are available for investments in the model. The results show that biomass availability and biofuel demand have a large impact on the choice of negative emission technology, where high competition for biomass favours DACCS rather than BECCS. The available biomass is prioritized for use in fuel production and sets the upper limit for BECCS. In this work, CHP plants are more competitive for BECCS implementation than pulp mills, due to the energy penalty for CHP plants having a smaller impact on the overall energy system performance. The findings indicate that in addition to considering techno-economic assessments of individual technologies, it is important to take into account the system context in which they operate
Low-Frequency Noise in Vertical InAs/InGaAs Gate-All-Around MOSFETs at 15 K for Cryogenic Applications
Low-frequency noise (LFN), or 1/ f -noise, can be used effectively to evaluate device reliability which is a major concern in analog as well as digital circuits. In this work, we present 1/ f -noise characterization of vertical InAs/InGaAs gate-all-around (GAA) MOSFETs with a 70-nm gate length ( LG ) measured at cryogenic temperatures down to 15 K. The measurements at cryogenic temperatures reveal that the physical mechanism of 1/ f -noise changes from carrier number fluctuations at 300 K to mobility fluctuations at 15 K. We conclude that the channel conduction at 15 K is dominated by the nanowire core instead of the nanowire surface due to the effect of the border and interface traps freezing out. Vertical InAs/InGaAs GAA MOSFETs at 15 K, due to reduced surface scattering, exhibit a low value of Hooge parameter, αH ~ 5×10-6 and also have a low input-referred gate voltage noise spectral density, SVG=4.3μV2μm2 Hz -1 that are important for reliable cryogenic circuit applications
Inhibition of MicroRNA-125a Promotes Human Endothelial Cell Proliferation and Viability through an Antiapoptotic Mechanism.
The microRNA-125a (miR-125a) is highly expressed in endothelial cells, but its role in vascular biology is not known. Endothelial cell proliferation and viability play an important role in endothelial healing, and we hypothesize that miR-125a regulates this process. The aim of the present study was to investigate if miR-125a controls human endothelial cell proliferation, viability and endothelial healing, and to assess the mechanisms involved. We showed that overexpression of miR-125a by transfection with miR-125a mimic reduced human umbilical vein endothelial cell (HUVEC) proliferation and viability, and stimulated apoptosis as demonstrated by a miR-125a-induced increase of the proportion of annexin V-positive cells monitored by flow cytometry. Moreover, we showed that the miR-125a mimic downregulated the antiapoptotic Bcl2 protein and upregulated caspase 3, suggesting that these two proteins represent molecular targets for miR-125a. Accordingly, transfection with miR-125a inhibitor, downregulating miR-125a expression, promoted HUVEC proliferation and viability, and reduced apoptosis. Importantly, transfection with miR-125a inhibitor promoted HUVEC tube formation in Matrigel, suggesting that reduction of miR-125a has a proangiogenic effect. In conclusion, downregulation of miR-125a through local transfection with miR-125a inhibitor might be a new way to enhance endothelial cell proliferation and viability, thereby promoting the reendothelialization observed in response to intimal injury. © 2014 S. Karger AG, Basel
Yb4LiGe4 - A Yb Mixed Valent Zintl Phase with Strong Electronic Correlations
Single-phase samples of Yb4LiGe4 and Yb5Ge4 were synthesized using high
frequency (HF) heat treatment. Yb4LiGe4 crystallizes in orthorhombic space
group Pnma with the Gd5Si4 type of crystal structure and lattice parameters a =
7.0571(1) Angs, b = 14.6239(1) Angs, and c = 7.6155(1) Angs. One Yb position in
Yb5Ge4 is substituted by the lithium atom and causes a distortion of the
germanium tetragons in Yb4LiGe4. Investigation of the electronic state of Yb
via magnetic susceptibility and X-ray absorption near-edge spectroscopy (XANES)
revealed a presence of two electronic states of ytterbium, 4f13 and 4f14 (mixed
valence), in Yb5Ge4 and Yb4LiGe4. Studies of the temperature dependence of the
electrical resistivity, magnetization, 7Li spin-lattice relaxation rate and the
specific heat indicate that strong electronic correlations are present in
Yb4LiGe4, and below approximately 50 K there is a competition between
ferromagnetic and antiferromagnetic correlations. Magnetic ordering in
Yb4LiGe4, if present, occurs below the reported antiferromagnetic transition
temperature of 1.7 K for Yb5Ge4.Comment: 27 Pages, 9 figures, Uncder revie
Effects of Spatial Speech Presentation on Listener Response Strategy for Talker-Identification
This study investigates effects of spatial auditory cues on human listeners' response strategy for identifying two alternately active talkers (“turn-taking” listening scenario). Previous research has demonstrated subjective benefits of audio spatialization with regard to speech intelligibility and talker-identification effort. So far, the deliberate activation of specific perceptual and cognitive processes by listeners to optimize their task performance remained largely unexamined. Spoken sentences selected as stimuli were either clean or degraded due to background noise or bandpass filtering. Stimuli were presented via three horizontally positioned loudspeakers: In a non-spatial mode, both talkers were presented through a central loudspeaker; in a spatial mode, each talker was presented through the central or a talker-specific lateral loudspeaker. Participants identified talkers via speeded keypresses and afterwards provided subjective ratings (speech quality, speech intelligibility, voice similarity, talker-identification effort). In the spatial mode, presentations at lateral loudspeaker locations entailed quicker behavioral responses, which were significantly slower in comparison to a talker-localization task. Under clean speech, response times globally increased in the spatial vs. non-spatial mode (across all locations); these “response time switch costs,” presumably being caused by repeated switching of spatial auditory attention between different locations, diminished under degraded speech. No significant effects of spatialization on subjective ratings were found. The results suggested that when listeners could utilize task-relevant auditory cues about talker location, they continued to rely on voice recognition instead of localization of talker sound sources as primary response strategy. Besides, the presence of speech degradations may have led to increased cognitive control, which in turn compensated for incurring response time switch costs
Application of optical diagnostics to the quantification of soot in n-alkane flames under diesel conditions
The present work pursues a twofold objective. On the one hand, the effect of fuel properties on soot formation has been analysed, under different engine operating conditions. On the other hand, sensitivity and performance of the three optical techniques has been evaluated, identifying their main advantages and drawbacks in the framework of the current study. LEM has been considered as the reference technique, as the measurement principle can be implemented without important limitations associated to the other two. Results highlight that larger molecules produce more soot than the smaller ones, with both reactivity and soot formation changing with the proportion of the heavier fraction. Despite describing similar trends, LEM and 2C do not provide the same KL values, with the pyrometry reaching some sort of saturation when increasing flame soot. A detailed analysis confirms that 2-Colar measurements are strongly biased by soot and temperature distribution inside the flame. Nevertheless, it could still be a good option for low sooting conditions. On the other hand, an attempt to calibrate LII signal by means of LEM measurements has been reported. This approach should make it possible to obtain additional information on the soot spatial distribution. However, inconsistencies have been identified which stem from the inherent limitations of LII technique in highly sooting conditions. (c) 2015 The Combustion Institute. Published by Elsevier Inc. All rights reserved.Authors wold like to acknowledge that part of this work has been funded by the Spanish Ministry of Science and Technology through project TRA2011-26359 and grant BES-2012-059721. Some other parts of this works were financially supported by "COMET K2 - Competence Centres for Excellent Technologies Programme" (project B03T02). In addition, the authors acknowledge that some equipment used in this work has been partially supported by FEDER project funds (FEDER-ICTS-2012-06)", framed in the operational program of unique scientific and technical infrastructure of the Ministry of Science and Innovation of Spain.Pastor Soriano, JV.; García Oliver, JM.; García Martínez, A.; Micó Reche, C.; Möller, S. (2016). Application of optical diagnostics to the quantification of soot in n-alkane flames under diesel conditions. Combustion and Flame. 164:212-223. https://doi.org/10.1016/j.combustflame.2015.11.018S21222316
Tillstånd och trender för arter och deras livsmiljöer
2015 års upplaga av den svenska rödlistan är den fjärde i ordningen. Den är baserad på IUCN:s rödlistningskriterier och revideras vart femte år. I rödlistan bedöms risken som enskilda arter av djur, växter och svampar löper att försvinna från Sverige. Bedömningen utförs av ArtDatabankens medarbetare i samverkan med över 100 externa experter, indelade i 14 expertkommittéer för olika organismgrupper. Under arbetet med 2015 års rödlista har tillstånd och trender bedömts för 21 600 arter och 1 318 lägre taxa (apomiktiska arter, underarter och varieteter), sammanlagt ca 22 900 taxa. Av de bedömda arterna klassificerades 2 029 som hotade (kategorierna CR, EN och VU) och 4 273 som rödlistade (inkluderar även kategorierna NT, RE och DD). Förhållandet mellan antalet rödlistade och antalet bedömda arter ar 19,8 %, vilket är ungefär samma värde som 2010 och 2005. I denna rapport jämförs antalet och andelen rödlistade arter mellan olika organismgrupper, biotoper, substrat och påverkansfaktorer. Texten ar indelad i en allmän del och åtta kapitel inriktade på olika landskapstyper. Landskapstyperna utgör en grov indelning av landets miljöer enligt följande kategorier: Skog, Jordbrukslandskap, Urbana miljöer, Fjäll, Våtmarker, Sötvatten, Havsstränder och Havsmiljöer. Skogen och jordbrukslandskapet är de artrikaste landskapstyperna med 1 800 respektive 1 400 arter som har en stark anknytning dit, och ytterligare flera hundra arter som förekommer där mer sporadiskt. De faktorer som påverkar flest rödlistade arter i Sverige är skogsavverkning och igenväxning, som båda utgör ett hot mot vardera ca 30 % av de rödlistade arterna. Avverkning minskar arealen av skog där naturliga strukturer och naturlig dynamik upprätthålls, och den orsakar därmed förlust av livsmiljöer. Igenväxning orsakas av ett antal faktorer, bland annat upphörande hävd (bete och slåtter), gödsling, trädplantering och brist på naturliga störningsregimer som t.ex. regelbundna översvämningar kring vattendrag och sjöar. Andra viktiga påverkansfaktorer är fiske, torrläggning av våtmarker, tillbakagång hos värdarter (främst alm och ask som drabbats av invasiva svampsjukdomar), klimatförändringar och konkurrens från invasiva arter. IUCN:s rödlisteindex beräknas för ett urval av de bedömda organismgrupperna. Rödlisteindex visar att skillnaderna mellan rödlistorna från 2000, 2005, 2010 och 2015 är små. Ett par undantag finns dock. Groddjur och stora däggdjur har fått en något förbättrad situation sedan 2000. Totalt förefaller det ändå som att trycket mot Sveriges artstock har förblivit relativt konstant under de senaste 15 åren
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