Electronic Resources: The Ohio State University EESEE Project

Electronic resources aid in the teaching and learning of statistics by providing data that may be used interactively by teachers and students. By interacting with the data students are encouraged to discover knowledge and thereby gain a deeper understanding of statistical concepts. The Electronic Encyclopedia of Statistical Examples and Exercises (EESEE) is an electronic resource that includes over 80 'real-world' examples about the uses and abuses of statistics. These examples are drawn from published and printed media and the diverse range of subject-matter areas make it suitable for use in any statistics course.     

On the possibility of using organic phosphors in thermoluminescence dosimetry

Organic materials in general and polymers in particular have traditionally been considered as to be phosphors and have been ruled out as materials which could be useful in dosimetry of ionizing radiations by thermoluminescence. Some results reported during the past decade suggested possibilities of organic phosphors with good thermoluminescence characteristics. Experiments were undertaken to exploit the various possibilities. The results show that “crystalline polymers” can have adequate thermoluminescence properties to be useful in dosimetry. It is suggested that further studies on thermoluminesence in crystalline polymers and highly drawn fibers of high polymers will prove fruitful.     

Studies on azaspiracid biotoxins. III. Instrumental validation for rapid quantification of AZA 1 in complex biological matrices

Azaspiracids are neurotoxins produced by marine algae that have been detected in harvested mussels since 1995. They pose a significant threat to human health through the consumption of contaminated shellfish, and negatively impact the economy of areas where shellfish are harvested and processed. Regulatory agencies are beginning to advocate instrumental assays over traditional mouse bioassay methods. The development and validation of an assay method for AZA 1, the predominant azaspiracid toxin, and the production of a calibration standard and reference material will therefore be vital for quality control in monitoring laboratories worldwide. This report demonstrates a rapid and reproducible liquid chromatography/mass spectrometry (LC/MS) method for separation of all twelve known azaspiracids. Using a triple-quadrupole mass spectrometer, ultra-high sensitivity was obtained at the low-femtogram level injected on-column. At the same time, a linear response of three orders of magnitude was observed. We compared the results with those measured on an ion-trap mass spectrometer. The triple-quadrupole instrument was more sensitive, reliable and reproducible than the ion-trap instrument. The detection limit obtained on the ion-trap mass spectrometer was ten times higher than that obtained on the triple quadrupole. During the study, a new azaspiracid analog (AZA 7c) was discovered.     

Inhibition of Hsp90 with Resorcylic Acid Macrolactones: Synthesis and Binding Studies

A series of resorcylic acid macrolactones, analogues of the natural product radicicol has been prepared by chemical synthesis, and evaluated as inhibitors of heat shock protein 90 (Hsp90), an emerging attractive target for novel cancer therapeutic agents. The synthesis involves acylation of an ortho‐toluic acid dianion, esterification, followed by a ring‐closing metathesis to form the macrocycle. Subsequent manipulation of the protected hydroxymethyl side chain allows access to a range of new analogues following deprotection of the two phenolic groups. Co‐crystallization of one of the new macrolactones with the N‐terminal domain of yeast Hsp90 confirms that it binds in a similar way to the natural product radicicol and to our previous synthetic analogues, but that the introduction of the additional hydroxymethyl substituent appears to result in an unexpected change in conformation of the macrocyclic ring. As a result of this conformational change, the compounds bound less favorably to Hsp90.     

Luminescence of Ce in some chloroaluminates

Chloroaluminate systems are important due to their use in the production of aluminum and sodium metals, in electro-deposition of aluminum alloys, extraction of aromatic hydrocarbons, etc. However, no data on luminescence in these compounds are available. Low melting points and instability due to the high volatility of AlCl₃ seem to be deterrents for carrying out such investigations. Synthesis and photoluminescence spectra of Ce³⁺ activated alkali chloroaluminates and some alkaline earth chloroaluminate phosphors are described for the first time in the present work. A simple wet chemical method is used for the preparation of the phosphor. Very intense emission was observed for LiCl·AlCl₃ and NaCl·AlCl₃. For the former, the emission attributable to d-f transitions is entirely in the UVA1 (ultraviolet A1) region. The intensity is comparable to that of a commercial phosphor. Ce³⁺ activated emission in the alkaline earth compounds CaCl₂·AlCl₃ and MgCl₂·2AlCl₃ was relatively much weaker.     

A PVC plasticized membrane sensor for nickel ions

A new PVC membrane sensor, which is highly selective towards Ni (II) ions, has been developed using a thiophene-derivative Schiff base as the ionophore. The best performance was exhibited by the membrane having the composition percentage ratio of 5:3:61:31 (ionophore:NaTPB:DBP:PVC) (w/w), where NaTPB is the anion excluder, sodium tetraphenylborate and DBP is the plasticizing agent (dibutyl phthalate). The membrane exhibited a good Nernstian response for nickel ions over the concentration range of 1.0 × 10⁻¹–5.0 × 10⁻⁶ M (limit of detection is 1.8 × 10⁻⁶ M) with a slope of 29.5 ± 1.0 mV per decade of activity. It has a fast response time of <20 s and can be used for a period of 4 months with good reproducibility. The sensor is suitable for use in aqueous solutions of a wide pH range of 3.2–7.9. The sensor shows high selectivity to nickel ions over a large number of mono-, bi- and trivalent cations. It has been successfully used as an indicator electrode in the potentiometric titration of nickel ions against EDTA and also for direct determination of nickel content in real samples – wastewater samples from electroplating industries and Indian chocolates.     

Fundamental frequency and tracheal pressure during three types of vocalizations elicited from anesthetized dogs

Electrical stimulation of the midbrain was used to elicit a variety of vocalizations from six anesthetized dogs. This study was conducted to investigate the ranges of and relationships between fundamental frequency of the vocalizations (F₀) and tracheal pressure (P_t) produced during the vocalizations. The vocalizations were described according to type (growl, howl, and whine); F₀ and P_t, as well as patterns of laryngeal muscle activity, were examined for each vocalization type. Natural-sounding growl and howl vocalizations were elicited from five dogs; three dogs also produced whines. With few exceptions, F₀ was categorically different for the three vocalization types (low for growls, average for howls, very high for whines). P_t values overlapped for the three vocalization types, although, on average, howls were produced with greater P_t than growls. Patterns and degrees of laryngeal muscle activity varied across and within vocalization types, but general findings were consistent with the presumed function of most of the muscles. Laryngeal muscle activity may help explain some of the variability in the acoustic and aerodynamic data.     

A space-efficient on-line method of computing quantile estimates

The task of computing an estimate for the quantile (ζ_q) for an unknown distribution F (i.e., F(ζ_q) = q) is usually performed by the “sample quantile” method, which computes the ?Nq? + 1 smallest element from the set of N observations, and thus requires that all N samples be retained in memory. This paper introduces a recursive method of estimating ζ_q based on the fact that if the terminal nodes of a uniform d-ary tree are assigned random values, independently drawn from a distribution F, then the minimax alue of the root node converges to a specified quantile of F for very tall trees. The new estimate is shown to be almost as precise as that produced by the sample quantile method and, like it, is guaranteed to converge to ζ_q when the sample is large for any arbitrary distribution F. However, in contrast to the sample quantile computation the proposed method requires the retention in storage of at most log₂N representative data points, where N is the number of samples observed in the past. Moreover, the estimate can be updated quickly using an average of 4, and a maximum of 2 log₂N, comparisons with each new observation.     

Reflectance spectra and thermoluminescence of NaBr coloured in an electrodeless discharge

A comparative study of the optical and thermoluminescent properties ofγ irradiated NaBr and NaBr coloured in an electrodeless discharge is reported. In discharge coloured NaBrF centre absorption maxima shifted with the colouration time. This is tentatively attributed to the formation ofE centres. Correspondingly, an additional peak was observed in thermoluminescence glow curve. It is suggested that the results are not characteristic of the method of colouration but rather of the imperfections inherent to the powders, and in a perfect (undeformed) single crystal such a phenomenon should not be observed.