Student understanding of rotational and rolling motion concepts

We investigated the common difficulties that students have with concepts related to rotational and rolling motion covered in the introductory physics courses. We compared the performance of calculus- and algebra-based introductory physics students with physics juniors who had learned rotational and rolling motion concepts in an intermediate level mechanics course. Interviews were conducted with six physics juniors and ten introductory students using demonstration-based tasks. We also administered free-response and multiple-choice questions to a large number of students enrolled in introductory physics courses, and interviewed six additional introductory students on the test questions (during the test design phase). All students showed similar difficulties regardless of their background, and higher mathematical sophistication did not seem to help acquire a deeper understanding. We found that some difficulties were due to related difficulties with linear motion, while others were tied specifically to the more intricate nature of rotational and rolling motion.Comment: 23 pages, 3 figures, 2 tables; it includes a multiple-choice test (in Appendix B

Aspects of four-jet production in polarized proton-proton collisions

We examine the intrinsic spin-dependence of the dominant $gg \rightarrow gggg$ subprocess contribution to four-jet production in polarized proton-proton collisions using helicity amplitude techniques. We find that the partonic level, longitudinal spin-spin asymmetry, $\hat{a}_{LL}$, is intrinsically large in the kinematic regions probed in experiments detecting four isolated jets. Such events may provide another qualitative or semi-quantitative test of the spin-structure of QCD in planned polarized $pp$ collisions at RHIC.Comment: 9 pages, LaTeX, 2 uuencoded postscript files attache

W and Z Polarization Effects in Hadronic Collisions

A Monte Carlo study of the polar and azimuthal angular distributions of the lepton pair arising from the decay of a $W$ or $Z$ boson produced at high transverse momentum in hadronic collisions is presented. In the absence of cuts on the final state leptons, the lepton angular distribution in the gauge boson rest frame is determined by the gauge boson polarization. Numerical results for the lepton angular distributions in the Collins--Soper frame with acceptance cuts and energy resolution smearing applied to the leptons are presented. In the presence of cuts, the lepton angular distributions are dominated by kinematic effects rather than polarization effects, however, some polarization effects are still observable on top of the kinematic effects. Polarization effects are highlighted when the experimental distributions are divided by the Monte Carlo distributions obtained using isotropic gauge boson decay.Comment: 23 pages (LaTeX) plus 13 postscript figures, MAD/PH/834, UCD--94--23. Figures are available from the authors or as a compressed tar file via anonymous ftp at phenom.physics.wisc.edu in directory ~pup/preprints/madph-94-834-figs.tar.

x-Dependent Polarized Parton Distributions

Using QCD motivated and phenomenological considerations, we construct x- dependent polarized parton distributions, which evolve under GLAP evolution, satisfy DIS data and are within positivity constraints. Each flavor is done separately and the overall set can be used to predict polarization asymmetries for various processes. We perform our NLO analysis strictly in x space, avoiding difficulties in moment inversion. Small-x results and other physical considerations are discussed.Comment: 30 pages, 11 Postscript figure

What We Can Learn About Nucleon Spin Structure From Recent Data

We have used recent polarized deep-inelastic scattering data from CERN and SLAC to extract information about nucleon spin structure. We find that the SMC proton data, the E142 neutron data and the deuteron data from SMC and E143 give different results for fractions of the spin carried by each of the constituents. These appear to lead to two different and incompatible models for the polarized strange sea. The polarized gluon distribution occuring in the gluon anomaly does not have to be large in order to be consistent with either set of experimental data. However, it appears that the discrepancies in the implications of these data cannot be resolved with any simple theoretical arguments. We conclude that more experiments must be performed in order to adequately determine the fraction of spin carried by each of the nucleon constituents.Comment: 23 page

‘Lower than a Snake’s Belly’ : Discursive Constructions of Dignity and Heroism in Low-Status Garbage Work

In this paper, we consider how dignity is discursively constructed in the context of work dominated by physicality and dirt. Based on semi-structured interviews with garbage workers, our analysis considers how the deprivations they experience are cast through discourses intended to construct their individual and collective worth. We consider the manner in which dignity maybe denied to such workers through popular repudiations of individuality and status. We demonstrate how this positioning arises from contact with physical dirt, and associations with socially dirty work based on ascriptions of servility, abuse and ambivalence. We go on to consider how garbage workers respond to this positioning through discourses of ‘everyday heroism’. Heroism is evoked through three interrelated narratives that speaks to a particular type of masculinity. The first takes the form of a classic process of reframing and recalibration through which workers not only renegotiate their public position and status, but also point to the inherent value to be had in working with dirt as part of that which we identify as a process of ‘affirmation’. The second narrative arises from the imposition of favourable social and occupational comparisons that effectively elevate garbage collectors’ social position. The third discourse—and previously unobserved in respect of garbage work—centres on paternalistic practices of care. Combined, these discourses disrupt the generally held view that dirty work is antithetical to heroism and wounds dignity

‘Lower than a snake’s belly’ : discursive constructions of dignity and heroism in low-status garbage work.

In this paper, we consider how dignity is discursively constructed in the context of work dominated by physicality and dirt. Based on semi-structured interviews with garbage workers, our analysis considers how the deprivations they experience are cast through discourses intended to construct their individual and collective worth. We consider the manner in which dignity maybe denied to such workers through popular repudiations of individuality and status. We demonstrate how this positioning arises from contact with physical dirt, and associations with socially dirty work based on ascriptions of servility, abuse and ambivalence. We go on to consider how garbage workers respond to this positioning through discourses of ‘everyday heroism’. Heroism is evoked through three inter-related narratives that speaks to a particular type of masculinity. The first takes the form of a classic process of reframing and recalibration through which workers not only renegotiate their public position and status, but also point to the inherent value to be had in working with dirt as part of that which we identify as a process of ‘affirmation’. The second narrative arises from the imposition of favourable social and occupational comparisons that effectively elevate garbage collectors’ social position. The third discourse—and previously unobserved in respect of garbage work—centres on paternalistic practices of care. Combined, these discourses disrupt the generally held view that dirty work is antithetical to heroism and wounds dignity