Effects of Water Temperature on Breeding Phenology,Growth, and Metamorphosis of Foothill Yellow‐Legged Frogs (Rana boylii): A Case Study of the Regulated Mainstem and Unregulated Tributaries of California's Trinity River

Many riverine organisms are well adapted to seasonally dynamic environments, but extreme changes in flow and thermal regimes can threaten sustainability of their populations in regulated rivers. Altered thermal regimes may limit recruitment to populations by shifting the timing of breeding activities and affecting the growth and development of early life stages. Stream‐dwelling anurans such as the foothill yellow‐legged frog (Rana boylii) in the Trinity River of northern California are model subjects for examining associations between water temperature and the timing of oviposition, hatching, and metamorphosis, and body condition and size of tadpoles and metamorphs. Breeding activity, hatching success, and metamorphosis occurred later, and metamorphs were smaller and leaner along the regulated and colder mainstem relative to six unregulated tributaries of the Trinity River. Persistently depressed summer water temperatures appear to play a seminal role in inhibited tadpole growth on the regulated mainstem and may be a causative factor in the pronounced decline of this population. Environmental flow assessments should account for the influence of the thermal regime on the development of vulnerable embryonic and larval life stages to improve outcomes for declining amphibian populations. Published 2014. This article is a U.S. Government work and is in the public domain in the USA.     

Smooth pursuit eye movements, attention, and schizophrenia

In previous studies, smooth pursuit eye movements (SPEM) have been shown to be disordered in about 70% of schizophrenics and about 45% of their first-degree relatives. In this report, the role of attention in these eye movements is addressed in three experiments (using as subjects schizophrenics, their first-degree relatives, and normals administered chloral hydrate) that recruit focused attention to the task. These studies show that voluntary attention in the form of inattention, "heedless negligence," or failure to cooperate, is not the specific attentional quality that is disordered in SPEM of schizophrenics and their relatives. Rather, the data both indicate that nonvoluntary attending is specifically disordered in these persons, and implicate a neurophysiological substrate that can be described as a failure of inhibitory, synchronizing integrating systems which may be located in the brain stem.     

A television scanner for the ultracentrifuge. II. Multiple cell operation

The "Optical Multichannel Analyzer" (OMA) is a commercially available instrument that with the absorption optical system of the ultracentrifuge, provides an entire 500 channel intensity profile of a cell in real time. With its own analog-todigital converter, the OMA integrates a selectable number of 32.8 msec scans to provide a time-averaged image in digital form. This paper describes an interface-controller for operation of the OMA with single- and double-sector cells in multi-cell rotors, simulating double-beam measurement required for absorbance determinations. The desired sector is selected by "gating" the intensifier stage of a "Silicon Intensified Target" vidicon (SIT) used as the light detector. The cell location in the rotor and the position of the gate relative to the cell centerline is obtained from a phase-locked loop circuit which divides each rotation of the rotor into 3600 parts independent of rotor speed. (This circuit employed with photo-multiplier scanners would select the gate position for integration of photomultiplier pulses.) From examination of appropriate signals with an oscilloscope, it was verified that gate positions and widths are located with an accuracy of 0.1degree or better and with a precision of +/- 0.1 mus. The light intensity profile for any desired cell can be examined in "real time", even during acceleration of the rotor. Additional circuits employing a 10 MHz crystal clock 1) control the automatic collection of data for all sectors in multicell rotors at digitally selected time intervals, 2) display the rotor speed, and 3) indicate the elapsed time of the experiment. Constructed but not tested are additional circuits for pulsing a laser into the absorption or Rayleigh optical system. The accuracy of the pulsed SIT has been demonstrated by measurement of absorbances of solutions and also by sedimentation equilibrium experiments with myoglobin. The estimated error is 0.003 for absorbances ranging from 0 to 1. The interface-controller operates extremely well, but problems related to the pulsed SIT (optimum gate position relative to the sector opening shape of high-voltage pulse, slight pincushion distortion) require more work.     

Particle/plasticizer relationship during dry blending

The time for a PVC resin to dry blend or to become a free flowing mix, when blended with a plasticizer in an elevated processing mode, is a common concern for manufacturers of flexible PVC products. The limiting factor in some processes is the dry blending cycle time. Longer dry blending times increase manpower and energy cost per mixer batch. Each flexible PVC compounder has some type of quality control test he uses to assess a resin's dry-up properties. This paper examines the relationship of resin particles and plasticizer during dry-up testing of intermediate to high molecular weight PVC resins. Through this examination, a better understanding of the factors that control dry-up times was achieved. Also included is a comparison of quality control dry-up times and mix cycle times in production size mixers.     

Structure of hydroperoxides obtained from autoxidized methyl linoleate

Summary A sample of debromination methyl linoleate has been autoxidized to a peroxide value of 671 m.e./kg. at approximately 0°C. in the dark. An essentially pure concentrate of methyl octadecadienoate monohy-droperoxide was quantitatively separated; infrared and ultraviolet spectral studies were made on the peroxide concentrate and on the corresponding hydroxyl derivative obtained by reducing the peroxides with stannous chloride. The infrared data showed no conjugated peroxides having geometric configurations other than cis, trans; the same data also showed that the peroxide concentrate contained at least 90% conjugated cis,trans forms. Calculations based on ultraviolet spectrophotometric methods also indicated that the peroxides were at least 90% conjugated. The remaining 10% of the sample is most likely nonconjugated diene hydroperoxide. Since analogous cis, cis conjugated dienes have not been isolated and their infrared and ultraviolet properties are unknown, their presence here in small amounts is possible. Ultraviolet and infrared spectra of the reduced compounds conform closely to those of the peroxides except for reduction in the intensity of the OH bond at 2.88 μ. The infrared absorption spectra of the C−H structure and carbonyl groups of an essentially pure conjugated cis, trans methyl octadecadienoate monohydroperoxide were recorded, using a LiF prism. The infrared absorption spectra of the C−H strucfraction isolated from methyl linoleate autoxidized in the dark at 24°C. indicated that appreciable amounts of conjugated trans, trans hydroperoxides were present, in addition to those of the cis, trans type. It is possible that the conjugated cis, trans isomers were formed originally but were labile at the higher temperature and in the presence of catalysts (e.g., peroxides) were transformed to the thermodynamically more stable conjugated trans, trans isomer. This work was supported in part by a contract between the Office of Naval Research, Department of the Navy, and the University of Minnesota. Hormel Institute publication No. 81, and paper No. 133, Journal Series, General Mills Research Laboratories.     

Removable foams based on an epoxy resin incorporating reversible Diels–Alder adducts

We have successfully incorporated Diels–Alder reversible chemistry into epoxy resins. The Diels–Alder chemistry goes in the forward direction at 60 °C and reverses at or above 90 °C. One resin was formulated with other commercial ingredients into foamed epoxy. The foam, shown to have mechanical properties similar to foams formed with conventional epoxy resins, is being utilized for electronic encapsulation. Because of the built‐in reversible chemistry, the foams can be easily removed by dissolution in 1‐butanol at 90 °C. Removal allows for the rework, upgrading, or dismantlement of the electronic components. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1496–1502, 2002     

Determination of peak expiratory flow

It is still unknown whether peak expiratory flow (PEF) is determined by "wave speed" flow limitation in the airways. To investigate the influences of airway mechanical properties on PEF, five healthy adults performed maximal forced expiratory effort (MFEE) manoeuvres, in the standard manner and following breathholds at total lung capacity (TLC) of 2 s and 10 s. Oesophageal pressure (Poes) was measured as an index of respiratory effort. Subjects also performed a MFEE following a 10 s breathhold during which intrathoracic pressure was voluntarily raised by a Valsalva manoeuvre, which would increase transmural pressure and cross-sectional area of the extrathoracic airway. Additional MFEEs were performed with the neck fully flexed and extended, to change longitudinal tracheal tension. In separate studies, PEF was measured with a spirometer and with a pneumotachograph. Breathholds at TLC (2 s and 10 s), and neck flexion reduced PEF by a mean of 9.8% (SD 2.9%), 9.6% (SD 1.6%), and 8.7% (SD 2.8%), respectively, when measured with the spirometer. The same pattern of results was seen when measured with the pneumotachograph. These reductions occurred despite similar respiratory effort. Voluntarily raising intrathoracic pressure during a 10 s breathhold did not reverse a fall in PEF. MFEE manoeuvre with neck extension did not result in an increase in PEF, the group mean % changes being -3.0% (SD 5.0%). We conclude that these results do not allow the hypothesis that "wave-speed" (Vws) is reached at PEF to be rejected. A breathhold at TLC could increase airway wall compliance by allowing stress-relaxation of the airway, thus reducing the "Vws" achievable.     

Processing of auditory stimuli during auditory and visual attention as revealed by event-related potentials

Auditory event-related brain potentials (ERPs) were recorded during auditory and visual selective attention tasks. Auditory stimuli consisted of frequent standard tones (1000 Hz) and infrequent deviant tones (1050 Hz and 1300 Hz) delivered randomly to the left and right ears. Visual stimuli were vertical line gratings randomly presented on a video monitor at mean intervals of 6 s. During auditory attention, the subject attended to the stimuli in a designated ear and responded to the 1300-Hz deviants occurring among the attended tones. During visual attention, the subject responded to the occasional visual stimuli. ERPs for tones delivered to the attended ear were negatively displaced relative to ERPs elicited by tones delivered to the unattended ear and to ERPs elicited by auditory stimuli during visual attention. This attention effect consisted of negative difference waves with early and late components. Mismatch negativities (MMNs) were elicited by 1300-Hz and 1050-Hz deviants irrespective of whether they occurred among attended or unattended tones. MMN amplitudes were unaffected by attention, supporting the proposal that the MMN is generated by an automatic cerebral discrimination process.     

Electric field-induced changes in agonist-stimulated calcium fluxes of human HL-60 leukemia cells

The mechanism of biological effects of extremely-low-frequency electric and magnetic fields may involve induced changes of Ca2+ transport through plasma membrane ion channels. In this study we investigated the effects of externally applied, low-intensity 60 Hz electric (E) fields (0.5 V/m, current density 0.8 A/m2) on the agonist-induced Ca2+ fluxes of HL-60 leukemia cells. The suspensions of HL-60 cells received E-field or sham exposure for 60 min and were simultaneously stimulated either by 1 microM ATP or by 100 microM histamine or were not stimulated at all. After E-field or sham exposure, the responses of the intracellular calcium levels of the cells to different concentrations of ATP (0.2-100 microM) were assessed. Compared with control cells, exposure of ATP-activated cells to an E-field resulted in a 20-30% decrease in the magnitude of [Ca2+]i elevation induced by a low concentration of ATP (<1 microM). In contrast, exposure of histamine-activated HL-60 cells resulted in a 20-40% increase of ATP-induced elevation of [Ca2+]i. E-field exposure had no effect on non-activated cells. Kinetic analysis of concentration-response plots also showed that compared with control cells, exposure to the E-field resulted in increases of the Michaelis constant, Km, value in ATP-treated cells and of the maximal [Ca2+]i peak rise in histamine-treated HL-60 cells. The observed effects were reversible, indicating the absence of permanent structural damages induced by acute 60 min exposure to electric fields. These results demonstrate that low-intensity electric fields can alter calcium distribution in cells, most probably due to the effect on receptor-operated Ca2+ and/or ion channels.