Macroeconomic Uncertainty and Firm Leverage

This paper investigates the link between the optimal level of nonfinancial firms' leverage and macroeconomic uncertainty. We develop a structural model of a firm's value maximization problem that predicts that as macroeconomic un-certainty increases the firm will decrease its optimal level of borrowing. We test this proposition using a panel of non{financial US firms drawn from the COM-PUSTAT quarterly database covering the period 1991{2001. The estimates confirm that as macroeconomic uncertainty increases, firms decrease their levels of leverage. Furthermore, we demonstrate that our results are robust with respect to the inclusion of the index of leading indicators.Leverage; Uncertainty; Non-financial firms; Panel data

Uncertainty Determinants of Corporate Liquidity

This paper investigates the link between the optimal level of non-financial firms' liquid assets and uncertainty. We develop a partial equilibrium model of precautionary demand for liquid assets showing that firms alter their liquidity ratio in response to changes in either macroeconomic or idiosyncratic uncertainty. We test this hypothesis using a panel of non-financial US firms drawn from the COMPUSTAT quarterly database covering the period 1993-2002. The results indicate that firms increase their liquidity ratios when macroeconomic uncertainty or idiosyncratic uncertainty increases.liquidity, uncertainty, non-financial firms, dynamic panel data

Magnetic excitations and amplitude fluctuations in insulating cuprates

We present results from light scattering experiments on three insulating antiferromagnetic cuprates, YBa$_2$Cu$_3$O$_{6.05}$, Bi$_2$Sr$_2$YCu$_2$O$_{8+\delta}$, and La$_2$CuO$_4$ as a function of polarization and excitation energy {using samples of the latest generation. From the raw data we derive symmetry-resolved spectra.} The spectral shape in $B_{1g}$ symmetry is found to be nearly universal and independent of the excitation energy. The spectra agree quantitatively with predictions by field theory [\onlinecite{Weidinger:2015}] facilitating the precise extraction of the Heisenberg coupling $J$. {In addition, the asymmetric line shape on the high-energy side is found to be related to amplitude fluctuations of the magnetization. In La$_2$CuO$_4$ alone minor contributions from resonance effects may be identified.} The spectra in the other symmetries are not universal. The variations may be traced back to weak resonance effects and extrinsic contributions. For all three compounds we find support for the existence of chiral excitations appearing as a continuum in $A_{2g}$ symmetry having an onset slightly below $3J$. In La$_2$CuO$_4$ an additional isolated excitation appears on top of the $A_{2g}$ continuum.Comment: 8 pages, 7 figure

Rule-based Location and Activity Recognition Based on Environmental Sensors

Tervishoiuteenuste kulude vähendamiseks on kasulik laiendada tervishoiusüsteemi ka kodukeskkonnale. Üks võimalus selleks on luua patsiendi kodusse sensorisüsteem, mille abil saab tervisevaldkonna spetsialist vajalikku infot patsiendi abistamiseks või raviks. Projektis SPHERE on sellesuunaliseks uurimistööks loodud eksperimentaalne maja, mis on sisustatud mitmesuguste sensoritega. Bakalaureusetöö eesmärgiks oli luua asukoha ja tegevuse tuvastamise jaoks automaatne reeglitepõhine süsteem SPHERE projekti maja jaoks. Töö käigus valmis süsteem, mis tuvastab edukalt peaaegu kõik ruumides viibimised, eksides valdavalt alla kahe sekundi. Tegevuste tuvastamiseks ei anna ruumisensorid palju võimalusi, millest tingitult tuvastatakse üksikuid tegevusi, mille ajalised eksimused jäävad alla kümne sekundi.It is useful to extend the health care system to home environment in order to reduce the healthcare costs. One solution for that would be to create a sensor system that provides helthcare professionals with necessary information for assisting patient's treatment. SPHERE project has developed an experimental building for mentioned purposes that is equipped with sensors. The aim of this bachelor’s thesis is to develop an automatic system that is capable of recognising human locations and activity using rule-based approach. The developed system is able to detect successfully all the rooms, where the patient has been with error less than two seconds most of the time. Room sensors don't give many opportunities for recognising activities, hence the system is capable of recognising a few of them while being mistaken less than ten seconds