PurposeTo evaluate the diagnostic value of the Korean version of the Douleur Neuropathique 4 (DN4) questionnaire and to validate this questionnaire in terms of psychometric properties in patients with chronic pain due to degenerative spinal disease.Materials and MethodsThe Korean version of the DN4 questionnaire, which was translated and linguistically validated by the MAPI Research Group, was tested on 83 patients with lumbar or lumbar-radicular pain. Test-retest reliability was evaluated in a subsample of 40 patients who completed two assessments with an interval of 2 weeks. Nociceptive pain and neuropathic component pain were diagnosed in 40 and 43 patients, respectively.ResultsThe Cronbach's α coefficient of internal consistency was 0.819, and the test-retest intraclass correlation coefficient (3, 1) (95% confidence interval) was 0.813 (0.776–0.847) (n=40). The area under the receiver-operator characteristics curve was 0.953 (p<0.001), with 95% confidence interval between 0.869 and 0.990. The Korean version of the DN4 questionnaire showed a sensitivity of 100% and 87.1%, and a specificity of 88.2% and 94.1% at the cutoff value of 3/10 and 4/10, respectively, for discriminating neuropathic component pain.ConclusionThe present study demonstrated the good discriminatory power of DN4 between nociceptive pain and neuropathic component pain in patients with lumbar or lumbar-radicular pain.

We study thermal-gravitational instability in simplified models for protogalactic halos using three-dimensional hydrodynamic simulations. The simulations started with isothermal density perturbations of various power spectra, and followed the evolution of gas with radiative cooling down to T = 10 4 K, background heating, and self-gravity for up to ∼ 20 cooling times. Then cooled and condensed clouds were identified and their physical properties were examined in detail. In our models, the cooling time scale is several times shorter than the gravitational time scale. Hence, during early stage clouds start to form around initial density peaks by thermal instability. Small clouds appear first and they are pressure-bound. Subsequently, the clouds grow through compression by the background pressure as well as gravitational infall. During late stage cloudcloud collisions become important, and clouds grow mostly through gravitational merging. Gravitationally bound clouds with mass M c 6 × 10 6 M ⊙ are found in the late stage. They are approximately in virial equilibrium and have radius R c ≃ 150 − 200 pc. Those clouds have gained angular momentum through tidal torque as well as merging, so they have large angular momentum with the spin parameter λ s ∼ 0.3. The clouds formed in a denser background tend to have smaller spin parameters, since the self-gravity, compared to the radiative cooling, is relatively less important at higher density. The H 2 cooling below T = 10 4 K does not drastically change the evolution and properties of clouds, since it is much less efficient than the H Lyα cooling. The slope of initial density power spectrum affects the morphology of cloud distribution, but the properties of individual

The unusual mushroom-shaped HI cloud, GW 123.4-1.5, is hundreds of parsecs in size but does not show any correlations to HI shells or chimney structures. To investigate the origin and velocity structure of GW 123.4-1.5, we perform three-dimensional hydrodynamical simulations of the collision of a high-velocity cloud with the Galactic disk. We also perform a parameter study of the density, radius, and incident angle of the impact cloud. The numerical experiments indicate that we reproduce the mushroom-shaped structure which resembles GW 123.4-1.5 in shape, size, position-velocity across the cap of the mushroom, and the density ratio between the mushroom and surrounding gas. GW 123.4-1.5 is expected to be formed by the almost head-on collision of a HVC with velocity ∼ 100 km s −1 and mass ∼ 10 5 M ⊙ about 5 × 10 7 yr ago. A mushroom-shaped structure like GW 123.4-1.5 must be infrequent on the Galactic plane, because the head-on collision which explains the mushroom structure seems rare for observed HVCs. HVC-disk collision explains not only the origin of the mushroomshaped structure but also the formation of a variety of structures like shells, loops, and vertical structures in our Galaxy.