Automatic tracking, feature extraction and classification of C elegans phenotypes

This paper presents a method for automatic tracking of the head, tail, and entire body movement of the nematode Caenorhabditis elegans (C. elegans) using computer vision and digital image analysis techniques. The characteristics of the worm's movement, posture and texture information were extracted from a 5-min image sequence. A Random Forests classifier was then used to identify the worm type, and the features that best describe the data. A total of 1597 individual worm video sequences, representing wild type and 15 different mutant types, were analyzed. The average correct classification ratio, measured by out-of-bag (OOB) error rate, was 90.9%. The features that have most discrimination ability were also studied. The algorithm developed will be an essential part of a completely automated C. elegans tracking and identification system.     

Creating permanent 3D arrangements of isolated cells using holographic optical tweezers

We report the creation of permanent 3D configurations of cells, at predefined positions, within a gelatin matrix. The technique used holographic optical tweezers to manipulate individual E. coli within a solution comprising monomer precursors. The matrix was then set and after the laser beam was removed, we were able to demonstrate that the structures remained intact for many days. We were also able to demonstrate that, in the presence of appropriate nutrients, the E. coli survived within the gelatin matrix for several days. The technique could have a number of potential future applications, including the arrangement of a variety of different cell types in complex architectures, as motifs for promoting tissue differentiation and growth within the field of cell engineering.     

On the invariance of classes under composition

The necessary and sufficient condition for to be in the class for every of that class whose range is in the domain of is that be in .

     

Measuring hearing in the harbor seal (Phoca vitulina): comparison of behavioral and auditory brainstem response techniques

Auditory brainstem response (ABR) and standard behavioral methods were compared by measuring in-air audiograms for an adult female harbor seal (Phoca vitulina). Behavioral audiograms were obtained using two techniques: the method of constant stimuli and the staircase method. Sensitivity was tested from 0.250 to 30 kHz. The seal showed good sensitivity from 6 to 12 kHz [best sensitivity 8.1 dB (re 20 microPa2 x s) RMS at 8 kHz]. The staircase method yielded thresholds that were lower by 10 dB on average than the method of constant stimuli. ABRs were recorded at 2, 4, 8, 16, and 22 kHz and showed a similar best range (8-16 kHz). ABR thresholds averaged 5.7 dB higher than behavioral thresholds at 2, 4, and 8 kHz. ABRs were at least 7 dB lower at 16 kHz, and approximately 3 dB higher at 22 kHz. The better sensitivity of ABRs at higher frequencies could have reflected differences in the seal's behavior during ABR testing and/or bandwidth characteristics of test stimuli. These results agree with comparisons of ABR and behavioral methods performed in other recent studies and indicate that ABR methods represent a good alternative for estimating hearing range and sensitivity in pinnipeds, particularly when time is a critical factor and animals are untrained.     

Finding prime pairs with particular gaps

By a prime gap of size , we mean that there are primes and such that the numbers between and are all composite. It is widely believed that infinitely many prime gaps of size exist for all even integers . However, it had not previously been known whether a prime gap of size existed. The objective of this article was to be the first to find a prime gap of size , by using a systematic method that would also apply to finding prime gaps of any size. By this method, we find prime gaps for all even integers from to , and some beyond. What we find are not necessarily the first occurrences of these gaps, but, being examples, they give an upper bound on the first such occurrences. The prime gaps of size listed in this article were first announced on the Number Theory Listing to the World Wide Web on Tuesday, April 8, 1997. Since then, others, including Sol Weintraub and A.O.L. Atkin, have found prime gaps of size with smaller integers, using more ad hoc methods. At the end of the article, related computations to find prime triples of the form , , and their application to divisibility of binomial coefficients by a square will also be discussed.

     

Hankel Operators on Bounded Analytic Functions

For a domain in the complex plane and a bounded measurable function on , the generalized Hankel operator on is the operator of multiplication by followed by projection into . Under certain conditions on we show that either is compact or there is an embedded on which is bicontinuous. We characterize those 's for which is compact in the case that is a Behrens roadrunner domain.

     

Eliminating false positive C4 sugar tests on New Zealand Manuka honey

Carbon isotope analyses (δ¹³C) of some New Zealand Manuka honeys show that they often fail the internationally recognised Association of Official Analytical Chemists sugar test (AOAC method 998.12) which detects added C₄ sugar, although these honeys are from unadulterated sources. Failure of these high value products is detrimental to the New Zealand honey industry, not only in lost export revenue, but also in brand and market reputation damage. The standard AOAC test compares the carbon isotope value of the whole honey and corresponding protein isolated from the same honey. Differences between whole honey and protein δ¹³C values should not be greater than +1.0‰, as it indicates the possibility of adulteration with syrups or sugars from C₄ plants such as high fructose corn syrup or cane sugar. We have determined that during the standard AOAC method, pollen and other insoluble components are isolated with the flocculated protein. These non‐protein components have isotope values which are considerably different from those of the pure protein, and can shift the apparent δ¹³C value of protein further away from the δ¹³C value of the whole honey, giving a false positive result for added C₄ sugar. To eliminate a false positive C₄ sugar test for Manuka honey, prior removal of pollen and other insoluble material from the honey is necessary to ensure that only the pure protein is isolated. This will enable a true comparison between whole honey and protein δ¹³C isotopes. Furthermore, we strongly suggest this modification to the AOAC method be universally adopted for all honey C₄ sugar tests. Copyright © 2010 John Wiley & Sons, Ltd.     

Two new characterizations of carleson-newman Blaschke products

We present an extension of a result of Vasyunin by giving a characterization of finite products of interpolating Blaschke products B in terms of the minorization of B(z) by the distance of z to the zeros of B. We also characterize those Blaschke products that satisfy the hereditary weak embedding property.     

Infrared and Mössbauer studies of some diamine complexes with trimethyltin halides and dimethyltin dihalides

To obtain more structural information on complexes formed between alkyltin halides and bidentate ligands, the solid-state IR and Mössbauer spectra of the 1,2-ethanediamine and 1,4-butanediamine complexes of trimethyltin halides and dimethyltin dihalides were examined. The structures of the trimethyltin halide complexes were found to be trigonal bipyramidal with coplnar methyl groups. The dimethyltin dihalide complexes were octahedral with the methyl groups in the cis-positions and the halides trans to each other. However, there were no differences in the structures of the chloro and bromo complexes of either type.