Inexpensive in situ time-integrating seawater nutrient sampler

An in situ time-integrating seawater sampler in which air escaping from the sample bottle through a capillary regulates flow of seawater into the sampler is described for determination of average plant nutrient concentration during a 10–50 h period. The sampler collected water at a constant rate which was approximately equal to that predicted from the Hagen-Poiseuille equation. The sampler has advantages over those described previously: it is less susceptible to blockage from suspended particulates in seawater, less expensive, and the seawater collection rate should be less temperature-dependent.     

A comparison of two correlation schemes

Processes involving the cross-correlation of two noisy data streams are frequently encountered in signal processing. The performances of two commonly used correlators, the simple and complex correlators, are examined. The conventional view is that the complex correlator is superior to the simple correlator by a factor of the square root of two in output signal-to-noise ratio (SNR). However, by modifying the simple correlator to utilize all the available information, its performance is improved. The development of the modified correlator is explained, and a computer simulation shows that this modified correlator is approximately equivalent to the complex correlator in noise performance     

Wavelength dependence of irreversible photobleaching of dye-doped polymer waveguide materials

We report the irreversible bleaching characteristics of 4-(dicyanomethylene)-2-methyl-6-(p-dimethyl aminostyryl)-4H-pyran (DCM) doped into perfluorocyclobutene (PFCB) and a new material known as DH-6 doped into amorphous polycarbonate (APC) by a monochromatic bleaching source. The wavelength dependent rate constants for the irreversible bleaching process are found, and the experimental bleaching characteristics are compared to the theoretical bleaching characteristics determined from a kinetic model of the bleaching process.     

Dantrolene inhibition of sarcoplasmic reticulum Ca2+ release by direct and specific action at skeletal muscle ryanodine receptors

The skeletal muscle relaxant dantrolene inhibits the release of Ca2+ from the sarcoplasmic reticulum during excitation-contraction coupling and suppresses the uncontrolled Ca2+ release that underlies the skeletal muscle pharmacogenetic disorder malignant hyperthermia; however, the molecular mechanism by which dantrolene selectively affects skeletal muscle Ca2+ regulation remains to be defined. Here we provide evidence of a high-affinity, monophasic inhibition by dantrolene of ryanodine receptor Ca2+ channel function in isolated sarcoplasmic reticulum vesicles prepared from malignant hyperthermia-susceptible and normal pig skeletal muscle. In media simulating resting myoplasm, dantrolene increased the half-time for 45Ca2+ release from both malignant hyperthermia and normal vesicles approximately 3.5-fold and inhibited sarcoplasmic reticulum vesicle [3H]ryanodine binding (Ki approximately 150 nM for both malignant hyperthermia and normal). Inhibition of vesicle [3H]ryanodine binding by dantrolene was associated with a decrease in the extent of activation by both calmodulin and Ca2+. Dantrolene also inhibited [3H]ryanodine binding to purified skeletal muscle ryanodine receptor protein reconstituted into liposomes. In contrast, cardiac sarcoplasmic reticulum vesicle 45Ca2+ release and [3H]ryanodine binding were unaffected by dantrolene. Together, these results demonstrate selective effects of dantrolene on skeletal muscle ryanodine receptors that are consistent with the actions of dantrolene in vivo and suggest a mechanism of action in which dantrolene may act directly at the skeletal muscle ryanodine receptor complex to limit its activation by calmodulin and Ca2+. The potential implications of these results for understanding how dantrolene and malignant hyperthermia mutations may affect the voltage-dependent activation of Ca2+ release in intact skeletal muscle are discussed.     

Adult attachment in a nationally representative sample.

The explosion of adult attachment research in the last decade has been limited by its reliance on college student and distressed samples. Using a large nationally representative sample of American adults, the authors examined the relation of sociodemographics, childhood adversity, parental representations, adult psychopathology, and personality traits to adult attachment in an effort to replicate previous findings and extend the theory. Distribution of adult attachment styles was similar to that in prior studies: 59% secure, 25% avoidant, and 11% anxious. Adult attachment was associated with several sociodemographic variables (e.g., income, age, race) not previously studied. Childhood adversities of an interpersonal nature were strongly related to insecure adult attachment. Various types of adult psychopathologies and personality traits were also strongly related to adult attachment. Implications for adult attachment theory and future research are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Mode dependence of splice loss in graded-index optical fibers

Various measurements of the mode dependence of loss in fusion splices are presented. Both laser diodes and light-emitting diodes are employed as sources and measurements are made using both the cutback method and the backscattering technique. Empirical relations, quantifying the form of the mode dependent loss function, are derived and discussed.     

Geological and Physical Factors Affecting the Friction Angle of Compacted Sands

This study evaluated the effects of physical characteristics and geologic factors on the shear strength of compacted sands from Wisconsin that are used as granular backfill for mechanically stabilized earth walls and reinforced soil slopes. Physical properties and shear strength were determined for 30 compacted sands collected from a broad range of geological deposits. Relationships between strength/deformation behavior, geologic origin, and physical properties were used to categorize the sands into four friction angle groups. Sands with the lowest friction angle are derived from weathering of underlying sandstones, and tend to be medium-fine, well-rounded, and poorly graded sands. Sands with the highest friction angle are from recent glacial activity and tend to be coarser grained, well-graded, and/or angular sands. A multivariate regression model was developed that can be used to predict friction angle (?′) of compacted sands from comparable geological origins based on effective particle size (D10), maximum dry unit weight (γdmax), and Krumbein roundness (Rs).     

Evaluation of defect-related diffusion in semiconductors byelectrooptical sampling

The electrooptical sampling technique is used to assess the electrical behavior of Ohmic contact regions in GaAs. For this purpose unique Ohmic contact coplanar waveguides were fabricated and tested. A reduced electrooptical sampling signal is detected in certain Ohmic contact regions. Since the electrical fields present in this device are known a priori, the deviation of the electrooptical signal from its nominal value is attributed to a deviation in the electrooptical coefficient. Defects introduced during the annealing step of the Ohmic contact accelerated by existing dislocations are discussed as a mechanism capable of disrupting the electrooptic coefficient. A simple phenomenological diffusion model is presented to explain the mechanism responsible for the nulling of the electrooptical coefficient     

Upper airway bypass surgery for obstructive sleep apnea syndrome

This article reviews the history of tracheostomy for sleep apnea syndrome along with current indications for temporary and permanent tracheostomy in these patients. Because most patients requiring tracheostomy for obstructive sleep apnea syndrome are morbidly obese and have a short thick neck, a skin-lined technique has been developed. This technique is described along with preoperative and postoperative care necessary to allow uneventful healing and prevent complications. Surgical techniques available for tracheostomy closure are also described.