Topic modeling,long texts and the best number of topics. Some Problems and solutions

Quality & Quantity - The main aim of this article is to present the results of different experiments focused on the problem of model fitting process in topic modeling and its accuracy when...     

Impact of treatment heterogeneity on drug resistance and supply chain costs

The efficacy of scarce drugs for many infectious diseases is threatened by the emergence and spread of resistance. Multiple studies show that available drugs should be used in a socially optimal way to contain drug resistance. This paper studies the tradeoff between risk of drug resistance and operational costs when using multiple drugs for a specific disease. Using a model for disease transmission and resistance spread, we show that treatment with multiple drugs, on a population level, results in better resistance-related health outcomes, but more interestingly, the marginal benefit decreases as the number of drugs used increases. We compare this benefit with the corresponding change in procurement and safety stock holding costs that result from higher drug variety in the supply chain. Using a large-scale simulation based on malaria transmission dynamics, we show that disease prevalence seems to be a less important factor when deciding the optimal width of drug assortment, compared to the duration of one episode of the disease and the price of the drug(s) used. Our analysis shows that under a wide variety of scenarios for disease prevalence and drug cost, it is optimal to simultaneously deploy multiple drugs in the population. If the drug price is high, large volume purchasing discounts are available, and disease prevalence is high, it may be optimal to use only one drug. Our model lends insights to policy makers into the socially optimal size of drug assortment for a given context.     

Does it add up? Early evidence on the data quality of XBRL filings to the SEC

In 2009, the Securities and Exchange Commission rolled out the first stage of a multi-year program to transition its EDGAR disclosure repository to the XBRL format. The quality of the XBRL data in the repository is vital for the success of the Commission’s interactive data program. A key aspect of the data quality of these filings is the correctness of the mathematical relationships implied by the taxonomy and implemented in the instance document. One quarter of the filings by the initial 400 large corporations in the first round of submissions had errors, with differences reported monetary facts and the sum of other monetary facts that were bound together in a computation relationship. The primary cause of these errors was inappropriate treatment in the instance documents of underlying debit/credit assumptions in the taxonomy. The results of the research have a number of implications for filers, the SEC, XBRL US, software vendors and the global XBRL community.     

Effect of electromagnetic field accompanying the magnetic resonance imaging on human heart rate variability – a pilot study

The effect of electromagnetic field on cardiovascular system in the literature is defined in ambiguous way. The aim of this study was to evaluate the effect of electromagnetic field on the heart rate variability (HRV) during the examination with magnetic resonance. Forty-two patients underwent Holter ECG heart monitoring for 30 minutes twice: immediately before and after the examination with magnetic resonance imaging (MRI). HRV was analysed by assessing a few selected time and spectral parameters. Is has been shown that standard deviation of NN intervals (SDNN) and very low frequency rates increased, whereas the low frequency:high frequency parameter significantly decreased following the MRI examination. These results show that MRI may affect the HRV most likely by changing the sympathetic-parasympathetic balance.