Complex Bifurcation from Real Paths

A new bifurcation phenomenon, called complex bifurcation, is studied. The basic idea is simply that real solution paths of real analytic problems frequently have complex paths bifurcating from them. It is shown that this phenomenon occurs at fold points, at pitchfork bifurcation points, and at isola centers. It is also shown that perturbed bifurcations can yield two disjoint real solution branches that are connected by complex paths bifurcating from the perturbed solution paths. This may be useful in finding new real solutions. A discussion of how existing codes for computing real solution paths may be trivially modified to compute complex paths is included, and examples of numerically computed complex solution paths for a nonlinear two point boundary value problem, and a problem from fluid mechanics are given

Mercury Levels in Marine and Estuarine Fishes of Florida 1989–2001. 2nd edition revised

The Florida Fish and Wildlife Conservation Commission’s Florida Marine Research Institute (FWC-FMRI) has examined total mercury levels in muscle tissue from a variety of economically and ecologically important species as part of an ongoing study to better understand mercury contamination in marine fishes.The FWC-FMRI Mercury Program is one of the most comprehensive programs in the United States for monitoring mercury levels in marine and estuarine fishes. Because mercury, a toxic metallic element, has been shown to bioaccumulate in fish tissue, humans consuming fish can potentially consume significant levels of mercury.We examined the concentration of total mercury in 6,806 fish, representing 108 species from 40 families. Species represented all major trophic groups, from primary consumers to apex predators.The majority of individuals we examined contained low concentrations of mercury, but concentrations in individual fish varied greatly within and among species. Species with very low mean or median mercury concentrations tended to be planktivores, detritivores, species that feed on invertebrates, or species that feed on invertebrates and small fish prey.Apex predators typically had the highest mercury concentrations. In most species, mercury concentration increased as fish size increased. Sampling in Florida waters is continuing, and future research relating mercury levels to fish age, feeding ecology, and the trophic structure of Florida’s marine and estuarine ecosystems will help us better understand concentrations of this element in marine fishes. (64pp.

Heat sink capability of jet A fuel - Heat transfer and coking studies

Heat sink capabilities of Jet-A fuel - heat transfer and coking studie

High-Frequency Microstrip Cross Resonators for Circular Polarization EPR Spectroscopy

In this article we discuss the design and implementation of a novel microstrip resonator which allows for the absolute control of the microwaves polarization degree for frequencies up to 30 GHz. The sensor is composed of two half-wavelength microstrip line resonators, designed to match the 50 Ohms impedance of the lines on a high dielectric constant GaAs substrate. The line resonators cross each other perpendicularly through their centers, forming a cross. Microstrip feed lines are coupled through small gaps to three arms of the cross to connect the resonator to the excitation ports. The control of the relative magnitude and phase between the two microwave stimuli at the input ports of each line allows for tuning the degree and type of polarization of the microwave excitation at the center of the cross resonator. The third (output) port is used to measure the transmitted signal, which is crucial to work at low temperatures, where reflections along lengthy coaxial lines mask the signal reflected by the resonator. EPR spectra recorded at low temperature in an S= 5/2 molecular magnet system show that 82%-fidelity circular polarization of the microwaves is achieved over the central area of the resonator.Comment: Published in Review of Scientific Instrument

The New Contact Binary GSC 2414-0797

Original article can be found at: http://www.konkoly.hu/ibvs/GSC 2414-0797 has a contact binary star type light curve, a 0.4 magnitude brightness variation with a period 0.3406 days.Peer reviewe

Letters between H. N. Henderson and William Kerr\u27s secretary

Letters concerning a position in athletic department at Utah Agricultural College

Kainate induced theta-frequency oscillatory network activity in the medial septum/diagonal band complex

The medial septum/diagonal band complex (MS/DB) forms part of the septo-hippocampal feedback loop and is thought to have a major functional role in the generation and/or maintenance of the hippocampal theta rhythm in vivo (4 * 15 Hz). Several different mechanistic scenarios may underlie the generation of a theta-frequency EEG pattern, amongst them (1) an external pacemaker-type input (2) theta activity being an emergent property of the septo-hippocampal feedback loop and (3) theta arising in the synaptic network of the MS/DB itself. This investigation tested the latter scenario by using an in vitro slice preparation of the (deafferented) MS/DB. Longitudinal slices (0.45 mm) from 21 day old rats were maintained at 32 deg C in an interface recording chamber perfused with oxygenated ACSF. Following the bath application of the AMPA/kainate receptor agonist kainate (25 *100 nM), extracellular recordings, using ACSF-filled micropipettes, showed rhythmic population activity with a mean peak frequency of ~6 Hz which was most prominent along the midline of the MS/DB. The higher concentrations of kainate were accompanied by corresponding increases in spectral power (amplitude). Subsequently, intracellular recordings were obtained with QX-314 containing electrodes to prevent spiking-activity, and thus allowing IPSPs to be recorded at depolarised membrane potentials. These recordings revealed the presence of rhythmic IPSPs (~6 Hz) in the class of fast-firing cells of oscillating MS/DB slices, presumably arising in the mutually connected interneuronal network of the MS/DB and pacing the oscillation. Moreover, these findings clearly demonstrate that the intrinsic circuitry of the isolated MS/DB complex is sufficient to generate rhythmic theta frequency activity