Addiction in context

The dissertation provides a comprehensive exploration of the interplay between social and cultural factors in substance use, specifically focusing on alcohol use disorder (AUD) and cannabis use disorder (CUD). It begins by introducing the concept of social plasticity, which posits that adolescents' susceptibility to AUD is influenced by their heightened sensitivity to their social environment, but this sensitivity increases the potential for recovery in the transition to adulthood.A series of studies delves into how social cues impact alcohol craving and consumption. One study using functional magnetic resonance imaging (fMRI) investigated social alcohol cue reactivity and its relationship to social drinking behavior, revealing increased craving but no significant change in brain activity in response to alcohol cues. Another fMRI study compared social processes in alcohol cue reactivity between adults and adolescents, showing age-related differences in how social attunement affects drinking behavior. Shifting focus to cannabis, this dissertation discusses how cultural factors, including norms, legal policies, and attitudes, influence cannabis use and processes underlying CUD. The research presented examined various facets of cannabis use, including how cannabinoid concentrations in hair correlate with self-reported use, the effects of cannabis and cigarette co-use on brain reactivity, and cross-cultural differences in CUD between Amsterdam and Texas. Furthermore, the evidence for the relationship between cannabis use, CUD, and mood disorders is reviewed, suggesting a bidirectional relationship, with cannabis use potentially preceding the onset of bipolar disorder and contributing to the development and worse prognosis of mood disorders and mood disorders leading to more cannabis use

Accuracy of Transillumination in the Recognition of Pneumothorax and Pneumomediastinum in the Neonate

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66508/2/10.1177_000992287701600404.pd

Application of Ground Penetrating Radar to the Detection of Subsurface Cavities

Ground Penetrating Radar (GPR) identifies subsurface features by distinguishing materials with different dielectric constants and electrical conductivities. Subsurface cavities can, therefore, be detected by the variation in their electrical properties from the electrical properties of the surrounding material. To test the cavity detection ability of GPR, subsurface cavities of varying size, shape and content were modeled. Radar response to the cavity models was found to be affected by the composition of the surrounding soil material, the depth of the groundwater table, and the radar signal frequency. Based on knowledge gained from the cavity modeling study, a natural subsurface cavity was identified during a GPR field investigation. Limestone features such as bedding planes and fractures were mapped, and a detailed lake bottom profile was obtained by the radar system

NMR study of molecular motions in two disordered organic solids

The molecular motions are studies in two disordered materials that undergo glass transitions. Glycerol is a conventional glass former and cyclohexanol is an orientational glass former.;The technique used in the glycerol experiments was spectral hole burning. Chemical shift anisotropy produces inhomogeneous broadening of NMR lines in orientationally disordered and polycrystalline solids. By saturating or inverting a portion of the anisotropic line, \u27burning a hole\u27, molecules of certain orientations are tagged. Subsequent molecular reorientations result in spectral diffusion which is not related to spin-spin interactions. By measuring the broadening and recovery of the hole as a function of time, detailed knowledge of the reorientation is obtained. For example, the mean jump rate and the lower limit of angular reorientations are determined. The reorientation rate in supercooled glycerol is followed from 10(\u27-2)s(\u27-1) to 10(\u272) s(\u27-1). Our measurements agreed with previous results and extended them to lower frequencies. The mean jump size was determined to be greater than 45 degrees. The hole recovery curves were not exponential, but were fitted with the Williams-Watts function, exp = ((tau)/(tau)(,0))(\u27(beta)) with (beta) = 0.5.;The motions in the rotor phase of solid cyclohexanol are studied with proton NMR from the melt down to 5 K. Particular attention is paid to the variation of the linewidth with temperature and to the temperature and frequency dependences of T(,1). We find there are two distinct motions that cause minima in T(,1) as a function of temperature. These two motions were observed in dielectric experiments. From the proton line narrowing and C(\u2713) high-resolution solid state spectra, the high temperature \u27(alpha)\u27 motion is identified as overall molecular rotation. The low temperature \u27(beta)\u27 motion is identified as a uniaxial internal rotation of the cyclohexyl ring about the CO bond, with the COH group remaining stationary. This explains both the strong spin relaxation and the weak dielectric relaxation peak associated with the (beta) motion. Both motions have distributions of correlation times, as seen from the shallow T(,1) minima and the weak temperature and frequency dependences of T(,1). From 100 K to 5 K, the temperature dependence continues to be weak. The frequency dependence remains less than (omega)(,0)(\u272). These results indicate that some components of the motion remain faster than the NMR frequency (omega)(,0) even at 5K. The behavior of cyclohexanol is compared to that of other disordered solids

Helicoidal surfaces with constant anisotropic mean curvature

We study surfaces with constant anisotropic mean curvature which are invariant under a helicoidal motion. For functionals with axially symmetric Wulff shapes, we generalize the recently developed twizzler representation of Perdomo to the anisotropic case and show how all helicoidal constant anisotropic mean curvature surfaces can be obtained by quadratures