Local Percolation Probabilities for a Natural Sandstone

Local percolation probabilities are used to characterize the connectivity in porous and heterogeneous media. Together with local porosity distributions they allow to predict transport properties \cite{hil91d}. While local porosity distributions are readily obtained, measurements of the local percolation probabilities are more difficult and have not been attempted previously. First measurements of three dimensional local porosity distributions and percolation probabilities from a pore space reconstruction for a natural sandstone show that theoretical expectations and experimental results are consistent.Comment: 9 pages, see also http://www.ica1.uni-stuttgart.de , Physica

Does text structure/summarization instruction facilitate learning from expository text?

The work upon which this publication is based was performed pursuant to Contract no. NIE-400-81-0030 of the National Institute of Educatio

Terahertz conductivity of the heavy-fermion compound UNi2Al3

We have studied the optical properties of the heavy-fermion compound UNi2Al3 at frequencies between 100 GHz and 1 THz (3 cm^-1 and 35 cm^-1), temperatures between 2 K and 300 K, and magnetic fields up to 7 T. From the measured transmission and phaseshift of radiation passing through a thin film of UNi2Al3, we have directly determined the frequency dependence of the real and imaginary parts of the optical conductivity (or permittivity, respectively). At low temperatures the anisotropy of the optical conductivity along the a- and c-axes is about 1.5. The frequency dependence of the real part of the optical conductivity shows a maximum at low temperatures, around 3 cm^-1 for the a-axis and around 4.5 cm^-1 for the c-axis. This feature is visible already at 30 K, much higher than the Neel temperature of 4.6 K, and it does not depend on external magnetic fields as high as 7 T. We conclude that this feature is independent of the antiferromagnetic order for UNi2Al3, and this might also be the case for UPd2Al3 and UPt3, where a similar maximum in the optical conductivity was observed previously.Comment: 7 pages, 9 figure

Estimating the Tempo of Audio Files

On the market today, there exists a multitude of software that allows for the detection and prediction of beats per minute (BPM) contained in audio files. There are both free and monetized versions of these programs, but there is one thing that they all have in common: they are inaccurate. This is simply because the science behind beat detection is unfinished, and may never be. In this project, I decided to use a method of audio peak detection to help me detect the tempo that may exist in any audio file. I started by researching existing programs and the science involved. The existing technologies are very complex, so I learned what I could, and I created my own implementation. My software is free, fairly accurate, and easy to use which is what I don\u27t see in today\u27s market

Reconstructing Electrocardiogram Leads From a Reduced Lead Set Through the Use of Patient-Specific Transforms and Independent Component Analysis

In this exploration into electrocardiogram (ECG) lead reconstruction, two algorithms were developed and tested on a public database and in real-time on patients. These algorithms were based on independent component analysis (ICA). ICA was a promising method due to its implications for spatial independence of lead placement and its adaptive nature to changing orientation of the heart in relation to the electrodes. The first algorithm was used to reconstruct missing precordial leads, which has two key applications. The first is correcting precordial lead measurements in a standard 12-lead configuration. If an irregular signal or high level of noise is detected on a precordial lead, the obfuscated signal can be calculated from other nearby leads. The second is the reduction in the number of precordial leads required for accurate measurement, which opens up the surface of the chest above the heart for diagnostic procedures. Using only two precordial leads, the other four were reconstructed with a high degree of accuracy. This research was presented at the 33rd International Conference of the IEEE Engineering in Medicine and Biology Society in 2011.1 The second algorithm was developed to construct a full 12-lead clinical ECG from either three differential measurements or three standard leads. By utilizing differential measurements, the ECG could be reconstructed using wireless systems, which lack the common ground necessary for the standard measurement method. Using three leads distributed across the expanse of the space of the heart, all twelve leads were successfully reconstructed and compared against state of the art algorithms. This work has been accepted for publication in the IEEE Journal of Biomedical and Health Informatics.2 These algorithms show a proof of concept, one which can be further honed to deal with the issues of sorting independent components and improving the training sequences. This research also revealed the possibility of extracting and monitoring additional physiological information, such as a patient\u27s breathing rate from currently utilized ECG systems