Medical Errors

Overview: Time of Death: 5:07 p.m. – Proceeding the solemn afternoon of February 22nd 2003, the Santillian family listened on as doctors told them that their cherished loved one was officially pronounced brain dead and would soon have to be taken off life support. Two weeks prior to this, seventeen-year-old Jesica Santillian received the thrilling news that she had finally been matched with a heart-lung donor and would be admitted to Duke University Medical Center in early February for a double-organ transplant. After years of living in pain brought on by her failing organs, Jesica was supposed to be one of the lucky ones, that is, until an ill-fated call received an hour after the new organs had been put in turned her luck upside down. The call was from a technician in the immunology lab saying that something had gone terribly wrong; Jesica’s blood type, type O, did not match the blood type her new organs, which were type A. What that meant was that Jesica’s life was in serious danger because the antibodies in her blood would shortly start attacking and destroying her new organs. Two weeks and an odds-shattering second set of donated organs later, the near death teenager’s family said their last goodbyes as the medication that kept her heart going was discontinued and her heart took its last untimely beat seven minutes later (Kopp 1)

Nebular Abundance Errors

The errors inherent to the use of the standard "ionization correction factor" ("i_CF") method of calculating nebular conditions and relative abundances of H, He, N, O, Ne, S, and Ar in emission line nebulae have been investigated under conditions typical for planetary nebulae. The photoionization code CLOUDY was used to construct a series of model nebulae with properties spanning the range typical of PNe. Its radial "profiles" of bright, frequently observed optical emission lines were then summed over a variety of "apertures" to generate sets of emission line measurements. These resulting line ratios were processed using the i_CF method to "derive" nebular conditions and abundances. We find that for lines which are summed over the entire nebula the i_CF-derived abundances differ from the input abundances by less than 5% for He and O up to 25% or more for Ne, S, and Ar. For resolved observations, however, the discrepancies are often much larger and are systematically variable with radius. This effect is especially pronounced in low-ionization zones where nitrogen and oxygen are neutral or once-ionized such as in FLIERs, ansae and ionization fronts. We argue that the reports of stellar-enriched N in the FLIERs of several PNe are probably specious.Comment: 22 pages, 4 tables, and 1 figure. Accepted for publication in the Astronomical Journal. Replaced to correct a referenc

Secrecy Through Synchronization Errors

In this paper, we propose a transmission scheme that achieves information theoretic security, without making assumptions on the eavesdropper's channel. This is achieved by a transmitter that deliberately introduces synchronization errors (insertions and/or deletions) based on a shared source of randomness. The intended receiver, having access to the same shared source of randomness as the transmitter, can resynchronize the received sequence. On the other hand, the eavesdropper's channel remains a synchronization error channel. We prove a secrecy capacity theorem, provide a lower bound on the secrecy capacity, and propose numerical methods to evaluate it.Comment: 5 pages, 6 figures, submitted to ISIT 201

Some problems and errors in cytogenetic biodosimetry

Human radiosensitivity is a quantitative trait that is generally subject to binomial distribution. Individual radiosensitivity, however, may deviate significantly from the mean (by 2-3 standard deviations). Thus, the same dose of radiation may result in different levels of genotoxic damage (commonly measured as chromosome aberration rates) in different individuals. There is significant genetic component in individual radiosensitivity. It is related to carriership of variant alleles of various single-nucleotide polymorphisms (most of these in genes coding for proteins functioning in DNA damage identification and repair); carriership of different number of alleles producing cumulative effects; amplification of gene copies coding for proteins responsible for radioresistance, mobile genetic elements, and others. Among the other factors influencing individual radioresistance are: radioadaptive response; bystander effect; levels of endogenous substances with radioprotective and antimutagenic properties and environmental factors such as lifestyle and diet, physical activity, psychoemotional state, hormonal state, certain drugs, infections and others. These factors may have radioprotective or sensibilising effects. Apparently, there are too many factors that may significantly modulate the biological effects of ionising radiation. Thus, conventional methodologies for biodosimetry (specifically, cytogenetic methods) may produce significant errors if personal traits that may affect radioresistance are not accounted for