Charles M. Breder, Jr.: Bahamas and Florida

Dr. Charles M. Breder, a well known ichthyologist, kept meticulous field diaries throughout his career. This publication is a transcription of field notes recorded during the Bacon Andros Expeditions, and trips to Florida, Ohio and Illinois during the 1930s. Breder's work in Andros included exploration of a "blue hole", inland ecosystems, and collection of marine and terrestrial specimens. Anecdotes include descriptions of camping on the beach, the "filly-mingoes" (flamingos) of Andros Island, the Marine Studios of Jacksonville, FL, a trip to Havana, and the birth of seahorses. This publication is part of a series of transcriptions of Dr. Breder's diaries. (PDF contains 55 pages

Delayed feedback as a means of control of noise-induced motion

Time--delayed feedback is exploited for controlling noise--induced motion in coherence resonance oscillators. Namely, under the proper choice of time delay, one can either increase or decrease the regularity of motion. It is shown that in an excitable system, delayed feedback can stabilize the frequency of oscillations against variation of noise strength. Also, for fixed noise intensity, the phenomenon of entrainment of the basic oscillation period by the delayed feedback occurs. This allows one to steer the timescales of noise-induced motion by changing the time delay.Comment: 4 pages, 4 figures. In the replacement file Fig. 2 and Fig. 4(b),(d) were amended. The reason is numerical error found, that affected the quantitative estimates of correlation time, but did not affect the main messag

Strong nonlinear optical response of graphene flakes measured by four-wave mixing

We present the first experimental investigation of nonlinear optical properties of graphene flakes. We find that at near infrared frequencies a graphene monolayer exhibits a remarkably high third-order optical nonlinearity which is practically independent of the wavelengths of incident light. The nonlinear optical response can be utilized for imaging purposes, with image contrasts of graphene which are orders of magnitude higher than those obtained using linear microscopy.Comment: 4 pages, 5 figure

Dimension Preference And Component Selection: Alternative Measures Of Children'S Attention To Stimulus Components 1

As children grow older they show an increasing preference for classifying objects on the basis of shape rather than color. To clarify the nature of this “dimension preference,” children of ages 3½ to 6½ years were given a method of triads test of dimension preferences, followed (after a week's delay) by a component selection task (see Hale & Morgan, 1973). The most notable results were these: (a) as expected, children below and above the median age differed in frequency of shape preference, (b) for children below the median age, higher component selection test scores were observed for the preferred dimension, although all scores were considerably above chance level and (c) no age difference was found in the relative magnitudes of the component selection scores. The results suggest that a “preference” for a particular dimension does not necessarily indicate a high degree of selective attention to that dimension. Also, the age difference in children's dimension preferences may be attributable to factors unrelated to selective attention.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/108298/1/ets200834.pd

A Comparison of Neuromuscular Electrical Stimulation and Acupuncture to Traditional Dysphagia Therapy In Stroke Patients

A comparison of neuromuscular electrical stimulation and acupuncture to traditional dysphagia therapy in reducing dysphagia in individuals who suffered a stroke

SP503-I Insects: Identifying the Flatheaded Appletree Borer and Other Buprestid Beetle Species in Tennessee

Version 2.

SP503-I Insects: Identifying the Flatheaded Appletree Borer and Other Buprestid Beetle Species in Tennessee

Version 2.

SP503-I Insects: Identifying the Flatheaded Appletree Borer and Other Buprestid Beetle Species in Tennessee

Version 2.

Magnetic Helicity Conservation and Astrophysical Dynamos

We construct a magnetic helicity conserving dynamo theory which incorporates a calculated magnetic helicity current. In this model the fluid helicity plays a small role in large scale magnetic field generation. Instead, the dynamo process is dominated by a new quantity, derived from asymmetries in the second derivative of the velocity correlation function, closely related to the `twist and fold' dynamo model. The turbulent damping term is, as expected, almost unchanged. Numerical simulations with a spatially constant fluid helicity and vanishing resistivity are not expected to generate large scale fields in equipartition with the turbulent energy density. The prospects for driving a fast dynamo under these circumstances are uncertain, but if it is possible, then the field must be largely force-free. On the other hand, there is an efficient analog to the $\alpha-\Omega$ dynamo. Systems whose turbulence is driven by some anisotropic local instability in a shearing flow, like real stars and accretion disks, and some computer simulations, may successfully drive the generation of strong large scale magnetic fields, provided that $\partial_r\Omega>0$. We show that this criterion is usually satisfied. Such dynamos will include a persistent, spatially coherent vertical magnetic helicity current with the same sign as $-\partial_r\Omega$, that is, positive for an accretion disk and negative for the Sun. We comment on the role of random magnetic helicity currents in storing turbulent energy in a disordered magnetic field, which will generate an equipartition, disordered field in a turbulent medium, and also a declining long wavelength tail to the power spectrum. As a result, calculations of the galactic `seed' field are largely irrelevant.Comment: 28 pages, accepted by The Astrophysical Journa