On the electromagnetic form factors of the proton from generalized Skyrme models

We compare the prediction of Skyrme-like effective Lagrangians with data for electromagnetic form factors of proton and consider the possibility of fixing the parameters of these higher-order Lagrangians. Our results indicate that one or two-parameter models can lead to better agreement with the data but more accurate determination of the effective Lagragian faces theoretical uncertainties.Comment: 8 pages, 2 figures, revte

Child Physical Abuse and Neglect

Although poor and inhumane treatment of children is not a new phenomenon (Doerner & Lab, 1998; Wolfe, 1999), child physical abuse and neglect were not identified as serious social problems until the 1960s, with the publication of Kempe and colleagues’ description of battered-child syndrome (Kempe, Silverman, Steele, Droegemueller, & Silver, 1962). In this influential study, Kempe and colleagues described the clinical manifestation of this syndrome in terms of the deleterious physical consequences maltreated children experienced, ranging from undetected outcomes to those that cause significant physical impairments. Rather than exploring the potential psychological sequelae of maltreated children, Kempe focused on detailing the psychiatric profiles of abusive parents. They concluded that, although not all maltreating parents possess severe psychiatric disturbances, “in most cases some defect in character structure is probably present; often parents may be repeating the type of child care practiced on them in their childhood” (p. 112). Since Kempe and colleagues’ original characterization of physical abuse, professionals have grappled with exactly how to define child maltreatment. As many have pointed out, child maltreatment is a complex and heterogeneous problem (e.g., Cicchetti, 1990; Wolfe & Mc- Gee, 1991; Zuravin, 1991) that is difficult to define (Wolfe, 1987, 1999). In a summary of definitional consider ations, Zuravin (1991) suggested that operational definitions of abuse and neglect should differentiate among subcategories of maltreating behavior and should consider issues such as severity and chronicity. Before we discuss the respective definitions of child physical abuse and neglect, we will briefly review the legal aspects of these definitions

A New Bound on Excess Frequency Noise in Second Harmonic Generation in PPKTP at the 10^-19 Level

We report a bound on the relative frequency fluctuations in nonlinear second harmonic generation. A 1064nm Nd:YAG laser is used to read out the phase of a Mach-Zehnder interferometer while PPKTP, a nonlinear crystal, is placed in each arm to generate second harmonic light. By comparing the arm length difference of the Mach Zehnder as read out by the fundamental 1064 nm light, and its second harmonic at 532 nm, we can bound the excess frequency noise introduced in the harmonic generation process. We report an amplitude spectral density of frequency noise with total RMS frequency deviation of 3mHz and a minimum value of 20 {\mu}Hz/rtHz over 250 seconds with a measurement bandwidth of 128 Hz, corresponding to an Allan deviation of 10^-19 at 20 seconds.Comment: Submitted to Optics Express June 201

Fermionic Symmetries: Extension of the two to one Relationship Between the Spectra of Even-Even and Neighbouring Odd mass Nuclei

In the single j shell there is a two to one relationship between the spectra of certain even-even and neighbouring odd mass nuclei e.g. the calculated energy levels of J=0^+ states in ^{44}Ti are at twice the energies of corresponding levels in ^{43}Ti(^{43}Sc) with J=j=7/2. Here an approximate extension of the relationship is made by adopting a truncated seniority scheme i.e. for ^{46}Ti and ^{45}Sc we get the relationship if we do not allow the seniority v=4 states to mix with the v=0 and v=2 states. Better than that, we get very close to the two to one relationship if seniority v=4 states are admixed perturbatively. In addition, it is shown that the higher isospin states do not contain seniority 4 admixtures.Comment: 11 pages, RevTex file and no figures, typos added, references changed and changed content

Development of a low-pressure ionization chamber for rare isotope experiments at IRIS

ix, 115 leaves : ill. (chiefly col.) ; 29 cm.Includes abstract and appendices.Includes bibliographical references (leaves 113-115).The ISAC charged particle reaction spectroscopy station (IRIS), a new experimental facility at TRIUMF, is developed to study light and heavy proton- and neutron-rich nuclei. Due to the production processes of these nuclei, besides the nucleus of interest, contaminants with the same mass number may be present. To identify these contaminants, IRIS employs a low-pressure ionization chamber (IC), which tags the atomic number of the particles in the beam as they pass through the IC prior to interacting with the reaction target; a first in a low energy facility (<15A MeV). The IRIS IC uses a coplanar anode system with sixteen independent anodes. Its characteristics were studied and optimized throughout this work by using a pulser and 241Am alpha source and two stable beams (18O, 40Ar). After parameter optimization, the results show that the IRIS IC has the capability to distinguish isobars at Z = 1 for the beams studied

Hyperpolarizability and operational magic wavelength in an optical lattice clock

Optical clocks benefit from tight atomic confinement enabling extended interrogation times as well as Doppler- and recoil-free operation. However, these benefits come at the cost of frequency shifts that, if not properly controlled, may degrade clock accuracy. Numerous theoretical studies have predicted optical lattice clock frequency shifts that scale nonlinearly with trap depth. To experimentally observe and constrain these shifts in an $^{171}$Yb optical lattice clock, we construct a lattice enhancement cavity that exaggerates the light shifts. We observe an atomic temperature that is proportional to the optical trap depth, fundamentally altering the scaling of trap-induced light shifts and simplifying their parametrization. We identify an "operational" magic wavelength where frequency shifts are insensitive to changes in trap depth. These measurements and scaling analysis constitute an essential systematic characterization for clock operation at the $10^{-18}$ level and beyond.Comment: 5 + 2 pages, 3 figures, added supplementa

Filtration of submicrometer particles by pelagic tunicates

Author Posting. © The Author(s), 2010. This is the author's version of the work. It is posted here by permission of National Academy of Sciences for personal use, not for redistribution. The definitive version was published in Proceedings of the National Academy of Sciences of the United States of America 107 (2010): 15129-15134, doi:10.1073/pnas.1003599107.Salps are common in oceanic waters and have higher per individual filtration rates than any other zooplankton filter feeder. Though salps are centimeters in length, feeding via particle capture occurs on a fine, mucous mesh (fiber diameter d ~ 0.1 μm) at low velocity (U = 1.6 ± 0.6 cm s-1, mean ± SD) and is thus a low-Reynolds number (Re ~ 10-3) process. In contrast to the current view that particle encounter is dictated by simple sieving of particles larger than the mesh spacing, a low-Re mathematical model of encounter rates by the salp feeding apparatus for realistic oceanic particle size distributions shows that submicron particles, due to their higher abundances, are encountered at higher rates (particles per time) than larger particles. Data from feeding experiments with 0.5, 1 and 3 μm diameter polystyrene spheres corroborate these results. Though particles larger than 1 μm (e.g. flagellates, small diatoms) represent a larger carbon pool, smaller particles in the 0.1–1 μm range (e.g. bacteria, Prochlorococcus) may be more quickly digestible because they present more surface area, and we find that particles smaller than the mesh size (1.4 μm) can fully satisfy salp energetic needs. Furthermore, by packaging submicrometer particles into rapidly sinking fecal pellets, pelagic tunicates can substantially change particle size spectra and increase downward fluxes in the ocean.This work was supported by the National Science Foundation (OCE-0647723 to LPM and OCE-074464- CAREER to RS) and the WHOI Ocean Life Institute