Robustness of subwavelength devices: a case study of cochlea-inspired rainbow sensors

The aim of this work is to derive precise formulas which describe how the properties of subwavelength devices are changed by the introduction of errors and imperfections. As a demonstrative example, we study a class of cochlea-inspired rainbow sensors. These are devices based on a graded array of subwavelength resonators which have been designed to mimic the frequency separation performed by the cochlea. We show that the device's properties (including its role as a signal filtering device) are stable with respect to small imperfections in the positions and sizes of the resonators. Additionally, if the number of resonators is sufficiently large, then the device's properties are stable under the removal of a resonator

Microelectrophoresis of selected mineral particles

Particle mobilities of ilmenite, labradorite plagioclase, enstatite pyroxene, and olivine were measured with a Rank microelectrophoresis system to evaluate indicated mineral separability. Sodium bicarbonate buffer suspension media with and without additives (0.0001 M DTAB and 5 percent v/v ethylene glycol) were used to determine differential adsorption by mineral particles and modification of relative mobilities. Good separability between some minerals was indicated; additives did not enhance separability

Routine water monitoring test for mutagenic compounds

We have developed a simple, relatively comprehensive method for the recovery of nonvolatile mutagenic compounds from surface waters. The method recovers compounds by sequential passage of the water sample through a silica gel bed (to mechanically filter the sample and to adsorb water-insoluble compounds such as polynuclear aromatic hydrocarbons), then a cation-exchange bed (to adsorb cationic and amphoteric compounds), and then an anion-exchange bed-all contained in a single multi-bed column of glass and teflon, the parfait column. Nonvolatile compounds not adsorbed to any of these beds (i.e., neutral, water soluble compounds) were recovered following concentration of the column effluent by vacuum distillation at < 30˚. The beds of the parfait column were separated and eluted independently. Water-soluble ionic compounds were eluted with 2 M triethylammonium carbonate, and hydrophobic compounds were eluted with acetone. Under vacuum, the acetone or the components of the triethylammonium carbonate buffer (triethylamine and C02) were removed, leaving the nonvolatile components of the water sample in the residue. Acetone residues were taken up in dimethylsulfoxide; the others were taken up S n water. Using the Ames Salmonella/microsome reversion assay, each residue was assayed for mutagenic activity. The method was evaluated by recovery of five known mutagens, benzo(a)pyrene, 4-nitroquinoline-1-oxide, ethidium bromide, nitrofurylfuramide, and sodium azide, each initially spiked into a sample of laboratory deionized water and an environmental water sample to a final concentration of less than 3 ppb. Recoveries were calculated from the mutagenic activity observed in the extracts, in comparison to the activity in parallel extracts of an unspiked water sample. Under these conditions, the parfait/distillation method was able to recover detectable mutagenic activity with three of the five mutagens tested. The method has been used to survey ten Illinois surface waters for naturally occurring mutagenic activity. Samples from two sites, the Fox River at Aurora, Illinois, and the Salt Fork Creek at Urbana, Illinois, showed significant mutagenic activity. The parfait distillation method differs from other techniques for the recovery of waterborne mutagens in its emphasis on the recovery of nonvolatile compounds and neutral water-soluble compounds. This method has a1 so detected significant mutagenic activity in samples as small as 2 gallons of water, a volume consumed by a normal person every few days. This study represents the first step in the development of a routine method for the assay of mutagens in drinking water and drinking water supplies. The results of this study and the strong correlation of mutagenic activity to carcinogenic potential raises the possibility that compounds present in surface waters may pose a chronic threat to the public's health.U.S. Department of the InteriorU.S. Geological SurveyOpe

Age- and Gender-Specific Normative Data of Grip and Pinch Strength in a Healthy Adult Swiss Population

Assessment of hand strength is used in a wide range of clinical settings especially during treatment of diseases affecting the function of the hand. This investigation aimed to determine age- and gender-specific reference values for grip and pinch strength in a normal Swiss population with special regard to old and very old subjects as well as to different levels of occupational demand. Hand strength data were collected using a Jamar dynamometer and a pinch gauge with standard testing position, protocol and instructions. Analysis of the data from 1023 tested subjects between 18 and 96 years revealed a curvilinear relationship of grip and pinch strength to age, a correlation to height, weight and significant differences between occupational groups. Hand strength values differed significantly from those of other populations, confirming the thesis that applying normative data internationally is questionable. Age- and gender-specific reference values for grip and pinch strength are presented

The C. elegans EMAP-like protein, ELP-1 is required for touch sensation and associates with microtubules and adhesion complexes

<p>Abstract</p> <p>Background</p> <p>The founding member of the EMAP-like protein family is the Echinoderm Microtubule-Associated Protein (EMAP), so-named for its abundance in sea urchin, starfish, and sand dollar eggs. The EMAP-like protein family has five members in mammals (EML1 through EML5) and only one in both <it>Drosophila </it>(ELP-1) and <it>C. elegans </it>(ELP-1). Biochemical studies of sea urchin EMAP and vertebrate EMLs implicate these proteins in the regulation of microtubule stability. So far, however, the physiological function of this protein family remains unknown.</p> <p>Results</p> <p>We examined the expression pattern of <it>C. elegans </it>ELP-1 by means of transgenic gene expression in living embryos and adults, and by immunolocalization with an ELP-1-specific antibody in fixed tissues. In embryos, ELP-1 is expressed in the hypodermis. In larvae and adults, ELP-1 is expressed in the body wall, spermatheca and vulval muscles, intestine, and hypodermal seam cells. In muscle, ELP-1 is associated with adhesion complexes near the cell surface and is bound to a criss-crossing network of microtubules in the cytoplasm. ELP-1 is also expressed in a subset of mechanoreceptor neurons, including the ray neurons in the male tail, microtubule-rich touch receptor neurons, and the six ciliated IL1 neurons. This restricted localization in the nervous system implies that ELP-1 plays a role in mechanotransmission. Consistent with this idea, decreasing ELP-1 expression decreases sensitivity to gentle touch applied to the body wall.</p> <p>Conclusion</p> <p>These data imply that ELP-1 may play an important role during the transmission of forces and signals between the body surface and both muscle cells and touch receptor neurons.</p

The C. elegans EMAP-like protein, ELP-1 is required for touch sensation and associates with microtubules and adhesion complexes

Background: The founding member of the EMAP-like protein family is the Echinoderm Microtubule-Associated Protein (EMAP), so-named for its abundance in sea urchin, starfish, and sand dollar eggs. The EMAP-like protein family has five members in mammals (EML1 through EML5) and only one in both Drosophila (ELP-1) and C. elegans (ELP-1). Biochemical studies of sea urchin EMAP and vertebrate EMLs implicate these proteins in the regulation of microtubule stability. So far, however, the physiological function of this protein family remains unknown. Results: We examined the expression pattern of C. elegans ELP-1 by means of transgenic gene expression in living embryos and adults, and by immunolocalization with an ELP-1-specific antibody in fixed tissues. In embryos, ELP-1 is expressed in the hypodermis. In larvae and adults, ELP-1 is expressed in the body wall, spermatheca and vulval muscles, intestine, and hypodermal seam cells. In muscle, ELP-1 is associated with adhesion complexes near the cell surface and is bound to a criss-crossing network of microtubules in the cytoplasm. ELP-1 is also expressed in a subset of mechanoreceptor neurons, including the ray neurons in the male tail, microtubule-rich touch receptor neurons, and the six ciliated IL1 neurons. This restricted localization in the nervous system implies that ELP-1 plays a role in mechanotransmission. Consistent with this idea, decreasing ELP-1 expression decreases sensitivity to gentle touch applied to the body wall. Conclusion: These data imply that ELP-1 may play an important role during the transmission of forces and signals between the body surface and both muscle cells and touch receptor neurons