A nonlocal connection between certain linear and nonlinear ordinary differential equations/oscillators

We explore a nonlocal connection between certain linear and nonlinear ordinary differential equations (ODEs), representing physically important oscillator systems, and identify a class of integrable nonlinear ODEs of any order. We also devise a method to derive explicit general solutions of the nonlinear ODEs. Interestingly, many well known integrable models can be accommodated into our scheme and our procedure thereby provides further understanding of these models.Comment: 12 pages. J. Phys. A: Math. Gen. 39 (2006) in pres

Chiral perturbation theory

The main elements and methods of chiral perturbation theory, the effective field theory of the Standard Model below the scale of spontaneous chiral symmetry breaking, are summarized. Applications to the interactions of mesons and baryons at low energies are reviewed, with special emphasis on developments of the last three years. Among the topics covered are the strong, electromagnetic and semileptonic weak interactions of mesons at and beyond next--to--leading order in the chiral expansion, nonleptonic weak interactions of mesons, virtual photon corrections and the meson--baryon system. The discussion is limited to processes at zero temperature, for infinite volume and with at most one baryon.Comment: 84 pages, Latex, 11 PostScript figures (in separate file) embedded with epsfig.sty, complete ps file (compressed, uuencoded, 0.6 MB) available via email on request; to appear in Progr. Part. Nucl. Phys., vol. 3

The standard model at low energies

The hadronic sector of the standard model at low energies is described by a non--decoupling effective field theory, chiral perturbation theory. An introduction is given to the construction of effective chiral Lagrangians, both in the purely mesonic sector and with inclusion of baryons. The connection between the relativistic formulation and the heavy baryon approach to chiral perturbation theory with baryons is reviewed.Comment: Lectures given at the 6th Indian-Summer School on Intermediate Energy Physics, Prague, Aug. 1993, Latex, 26 pages (with a4.sty), UWThPh-1993-3

A First Search for Cosmogenic Neutrinos with the ARIANNA Hexagonal Radio Array

The ARIANNA experiment seeks to observe the diffuse flux of neutrinos in the 10^8 - 10^10 GeV energy range using a grid of radio detectors at the surface of the Ross Ice Shelf of Antarctica. The detector measures the coherent Cherenkov radiation produced at radio frequencies, from about 100 MHz to 1 GHz, by charged particle showers generated by neutrino interactions in the ice. The ARIANNA Hexagonal Radio Array (HRA) is being constructed as a prototype for the full array. During the 2013-14 austral summer, three HRA stations collected radio data which was wirelessly transmitted off site in nearly real-time. The performance of these stations is described and a simple analysis to search for neutrino signals is presented. The analysis employs a set of three cuts that reject background triggers while preserving 90% of simulated cosmogenic neutrino triggers. No neutrino candidates are found in the data and a model-independent 90% confidence level Neyman upper limit is placed on the all flavor neutrino+antineutrino flux in a sliding decade-wide energy bin. The limit reaches a minimum of 1.9x10^-23 GeV^-1 cm^-2 s^-1 sr^-1 in the 10^8.5 - 10^9.5 GeV energy bin. Simulations of the performance of the full detector are also described. The sensitivity of the full ARIANNA experiment is presented and compared with current neutrino flux models.Comment: 22 pages, 22 figures. Published in Astroparticle Physic

A measure on the set of compact Friedmann-Lemaitre-Robertson-Walker models

Compact, flat Friedmann-Lemaitre-Robertson-Walker (FLRW) models have recently regained interest as a good fit to the observed cosmic microwave background temperature fluctuations. However, it is generally thought that a globally, exactly-flat FLRW model is theoretically improbable. Here, in order to obtain a probability space on the set F of compact, comoving, 3-spatial sections of FLRW models, a physically motivated hypothesis is proposed, using the density parameter Omega as a derived rather than fundamental parameter. We assume that the processes that select the 3-manifold also select a global mass-energy and a Hubble parameter. The inferred range in Omega consists of a single real value for any 3-manifold. Thus, the obvious measure over F is the discrete measure. Hence, if the global mass-energy and Hubble parameter are a function of 3-manifold choice among compact FLRW models, then probability spaces parametrised by Omega do not, in general, give a zero probability of a flat model. Alternatively, parametrisation by the injectivity radius r_inj ("size") suggests the Lebesgue measure. In this case, the probability space over the injectivity radius implies that flat models occur almost surely (a.s.), in the sense of probability theory, and non-flat models a.s. do not occur.Comment: 19 pages, 4 figures; v2: minor language improvements; v3: generalisation: m, H functions of

Tightness of slip-linked polymer chains

We study the interplay between entropy and topological constraints for a polymer chain in which sliding rings (slip-links) enforce pair contacts between monomers. These slip-links divide a closed ring polymer into a number of sub-loops which can exchange length between each other. In the ideal chain limit, we find the joint probability density function for the sizes of segments within such a slip-linked polymer chain (paraknot). A particular segment is tight (small in size) or loose (of the order of the overall size of the paraknot) depending on both the number of slip-links it incorporates and its competition with other segments. When self-avoiding interactions are included, scaling arguments can be used to predict the statistics of segment sizes for certain paraknot configurations.Comment: 10 pages, 6 figures, REVTeX

Adrenalectomy-Produced Facilitation of Pavlovian Conditioned Cardiodecelerations in Immobilized Rats

Previous evidence has suggested that both hormonal and behavioral aspects of adrenal stress activation may contribute to heart rate (HR) conditioning during physical/pharmacological immobilization. Accordingly, four studies were conducted to determine if bilateral adrenalectomy facilitates stimulus-control over Pavlovian conditioned cardiodecelerations in rats immobilized either through physical restraint or neuromuscular paralysis. Plasma corticosterone assays were used as an index of the effectiveness of adrenal removal. The results showed that adrenalectomy facilitated both simple and discriminated Pavlovian conditioned cardiodecelerations in rats paralyzed with d-tubocurarine chloride (dTC) without significantly altering the characteristics of EMG recovery from paralysis. Similarly, adrenalectomy facilitated simple Pavlovian HR conditioning in physically restrained rats. The results suggest that adrenal activation may disrupt the parasympathetically-mediated Pavlovian conditioned cardiodeceleration in the physically-and dTC-immobilized rat. However, the specific nature of neuroendocrine mechanisms underlying cardiovascular conditioning during immobilization remains problematical.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/75069/1/j.1469-8986.1977.tb03371.x.pd

Recent Developments in Chiral Perturbation Theory

I review recent developments in chiral perturbation theory (CHPT) which is the effective field theory of the standard model below the chiral symmetry breaking scale. The effective chiral Lagrangian formulated in terms of the pseudoscalar Goldstone bosons ($\pi, \, K, \, \eta$) is briefly discussed. It is shown how one can gain insight into the ratios of the light quark masses and to what extent these statements are model--independent. A few selected topics concerning the dynamics and interactions of the Goldstone bosons are considered. These are $\pi \pi$ and $\pi K$ scattering, some non--leptonic kaon decays and the problem of strong pionic final state interactions. CHPT also allows to make precise statements about the temperature dependence of QCD Green functions and the finite size effects related to the propagation of the (almost) massless pseudoscalar mesons. A central topic is the inclusion of matter fields, baryon CHPT. The relativistic and the heavy fermion formulation of coupling the baryons to the Goldstone fields are discussed. As applications, photo--nucleon processes, the $\pi N$ $\Sigma$--term and non--leptonic hyperon decays are presented. Implications of the spontaneously broken chiral symmetry on the nuclear forces and meson exchange currents are also described. Finally, the use of effective field theory methods in the strongly coupled Higgs sector and in the calculation of oblique electroweak corrections is touched upon.Comment: TeX, 110 pages, 15 figures available upon request, BUTP-93/0