Reliability and validity study of the motiviation for fear (MOTIF) survey

The aim of this study was to determine psychometric properties of a newly created, 24-item functional measure of fear and anxiety for typically-developing adults (the Motivation for Fear; MOTIF). Participants initially included 1,277 college students ranging in age from 18-35. Participants were asked to complete the MOTIF, the Questions About Behavioral Function (QABF), the Sensation Seeking Scale- Form V, and the Depression Anxiety Stress Scales (DASS). Analyses were conducted on those scoring above a minimum threshold on a well-normed measure of anxiety (the DASS). An exploratory factory analysis, using scree plot and parallel analysis, as well as oblique rotation was run on the qualifying 583 participants. Scree plot indicated either a 3, 4, or 5 factor solution. Parallel analysis indicated no more than 5 factors. Results converged on a 4-factor simple structure solution with 18 items. The four functions (labeled distress, comfort-seeking, tangible, and escape) explained 43% of the variance. Internal consistency was .739, .809, .636, and .506 for the distress, comfort-seeking, tangible, and escape functions, respectively. Validity assessments were conducted using the QABF, the DASS, and the SSS-V. Results from these analyses revealed preliminary support for convergent validity (i.e., for distress and tangible functions) and discriminant validity was established. Recommendations for improving the psychometrics of this measure include increasing content validity, improving internal consistency, and determining test-retest reliability. Strengths, limitations, clinical implications, and future directions are discussed

The relationship between parent-adolescent conflict and academic achievement

Previous research has shown family conflict to have a detrimental effect on the academic functioning of children and adolescents. Most research conceptualizes family conflict as marital distress or divorce. Additional factors that have been shown to effect academic functioning include cognitive ability (i.e., intelligence), academic skills (e.g., homework behaviors), and amount of resources (i.e., socioeconomic status, SES). The present study investigated whether parent-adolescent conflict is related to adolescent academic achievement after accounting for cognitive ability and homework behaviors. Participants include 74 middle school students attending public school in a low-SES urban environment. Prior to conducting analyses, parent and adolescent reports of conflict were examined to determine whether one rater was more significantly correlated with academic achievement than the other. However, neither parent nor adolescent reports of conflict were significantly correlated with academic achievement, therefore, the average combined scores of parent and adolescent reports of conflict were used. Multiple heirarchical regression revealed that parent-adolescent conflict did not explain significantly more variance after accounting for cognitive ability and homework behaviors. The remaining analysis tested whether parent-adolescent conflict moderated the relationship between homework behaviors and academic achievement. This analysis revealed statistically significant results: the interaction between parent-adolescent conflict and homework behaviors explained an additional 4% of the variance. The direction of the interaction’s effect was surprising, however. Adolescents with neither high levels of homework problems nor high levels of parent-adolescent conflict performed the best. However, adolescents with high levels of reported homework problems and high levels of parent-adolescent conflict performed better on a measure of academic achievement than adolescents who only had one such difficulty. Possible reasons for such a finding are discussed

Evaporation of buffer gas-thermalized anions out of a multipole rf ion trap

We identify plain evaporation of ions as the fundamental loss mechanism out of a multipole ion trap. Using thermalized negative Cl- ions we find that the evaporative loss rate is proportional to a Boltzmann factor. This thermodynamic description sheds new light on the dynamics of particles in time-varying confining potentials. It specifically allows us to extract the effective depth of the ion trap as the activation energy for evaporation. As a function of the rf amplitude we find two distinct regimes related to the stability of motion of the trapped ions. For low amplitudes the entire trap allows for stable motion and the trap depth increases with the rf field. For larger rf amplitudes, however, rapid energy transfer from the field to the ion motion can occur at large trap radii, which leads to a reduction of the effective trapping volume. In this regime the trap depth decreases again with increasing rf amplitude. We give an analytical parameterization of the trap depth for various multipole traps that allows predictions of the most favorable trapping conditions.Comment: Phys. Rev. Lett., in pres

Bremsstrahlung in alpha-Decay Reexamined

A high-statistics measurement of bremsstrahlung emitted in the alpha decay of 210Po has been performed, which allows to follow the photon spectra up to energies of ~ 500 keV. The measured differential emission probability is in good agreement with our theoretical results obtained within the quasi classical approximation as well as with the exact quantum mechanical calculation. It is shown that due to the small effective electric dipole charge of the radiating system a significant interference between the electric dipole and quadrupole contributions occurs, which is altering substantially the angular correlation between the alpha particle and the emitted photon.Comment: 10 pages, 5 figures, v2: fix of small typo

A renormalisation approach to excitable reaction-diffusion waves in fractal media

Of fundamental importance to wave propagation in a wide range of physical phenomena is the structural geometry of the supporting medium. Recently, there have been several investigations on wave propagation in fractal media. We present here a renormalization approach to the study of reaction-diffusion (RD) wave propagation on finitely ramified fractal structures. In particular we will study a Rinzel-Keller (RK) type model, supporting travelling waves on a Sierpinski gasket (SG), lattice

Cryogenic micro-calorimeters for mass spectrometric identification of neutral molecules and molecular fragments

We have systematically investigated the energy resolution of a magnetic micro-calorimeter (MMC) for atomic and molecular projectiles at impact energies ranging from $E\approx13$ to 150 keV. For atoms we obtained absolute energy resolutions down to $\Delta E \approx 120$ eV and relative energy resolutions down to $\Delta E/E\approx10^{-3}$. We also studied in detail the MMC energy-response function to molecular projectiles of up to mass 56 u. We have demonstrated the capability of identifying neutral fragmentation products of these molecules by calorimetric mass spectrometry. We have modeled the MMC energy-response function for molecular projectiles and conclude that backscattering is the dominant source of the energy spread at the impact energies investigated. We have successfully demonstrated the use of a detector absorber coating to suppress such spreads. We briefly outline the use of MMC detectors in experiments on gas-phase collision reactions with neutral products. Our findings are of general interest for mass spectrometric techniques, particularly for those desiring to make neutral-particle mass measurements

Enhanced dielectronic recombination of lithium-like Ti19+ ions in external ExB fields

Dielectronic recombination(DR) of lithium-like Ti19+(1s2 2s) ions via 2s->2p core excitations has been measured at the Heidelberg heavy ion storage ring TSR. We find that not only external electric fields (0 <= Ey <= 280 V/cm) but also crossed magnetic fields (30 mT <= Bz <= 80 mT) influence the DR via high-n (2p_j nl)-Rydberg resonances. This result confirms our previous finding for isoelectronic Cl14+ ions [Bartsch T et al, PRL 82, 3779 (1999)] that experimentally established the sensitivity of DR to ExB fields. In the present investigation the larger 2p_{1/2}-2p_{3/2} fine structure splitting of Ti19+ allowed us to study separately the influence of external fields via the two series of Rydberg DR resonances attached to the 2s -> 2p_{1/2} and 2s -> 2p_{3/2} excitations of the Li-like core, extracting initial slopes and saturation fields of the enhancement. We find that for Ey > 80 V/cm the field induced enhancement is about 1.8 times stronger for the 2p_{3/2} series than for the 2p_{1/2} series.Comment: 10 pages, 3 figures, to be published in Journal of Physics B, see also http://www.strz.uni-giessen.de/~k

Dielectronic Recombination in Photoionized Gas. II. Laboratory Measurements for Fe XVIII and Fe XIX

In photoionized gases with cosmic abundances, dielectronic recombination (DR) proceeds primarily via nlj --> nl'j' core excitations (Dn=0 DR). We have measured the resonance strengths and energies for Fe XVIII to Fe XVII and Fe XIX to Fe XVIII Dn=0 DR. Using our measurements, we have calculated the Fe XVIII and Fe XIX Dn=0 DR DR rate coefficients. Significant discrepancies exist between our inferred rates and those of published calculations. These calculations overestimate the DR rates by factors of ~2 or underestimate it by factors of ~2 to orders of magnitude, but none are in good agreement with our results. Almost all published DR rates for modeling cosmic plasmas are computed using the same theoretical techniques as the above-mentioned calculations. Hence, our measurements call into question all theoretical Dn=0 DR rates used for ionization balance calculations of cosmic plasmas. At temperatures where the Fe XVIII and Fe XIX fractional abundances are predicted to peak in photoionized gases of cosmic abundances, the theoretical rates underestimate the Fe XVIII DR rate by a factor of ~2 and overestimate the Fe XIX DR rate by a factor of ~1.6. We have carried out new multiconfiguration Dirac-Fock and multiconfiguration Breit-Pauli calculations which agree with our measured resonance strengths and rate coefficients to within typically better than <~30%. We provide a fit to our inferred rate coefficients for use in plasma modeling. Using our DR measurements, we infer a factor of ~2 error in the Fe XX through Fe XXIV Dn=0 DR rates. We investigate the effects of this estimated error for the well-known thermal instability of photoionized gas. We find that errors in these rates cannot remove the instability, but they do dramatically affect the range in parameter space over which it forms.Comment: To appear in ApJS, 44 pages with 13 figures, AASTeX with postsript figure