Resonance Broadening Induced Nonlinear Saturation of Kinetic Alfven Turbulence in the Interplanetary Plasma

The saturation of ion cyclotron Alfven turbulence excited by beam particles is investigated using resonance broadening theory. The stochastic scattering which decorrelates particles, includes both random acceleration by electric fields and a turbulent magnetic mirroring effect. Turbulent mirroring is shown to yield non-Gaussian corrections to the orbits even if the random electric and magnetic fields are Gaussian. The predicted steady-state turbulence level exhibits a peaked anglular distribution, with a maximum near Theta ~ 60 degrees.Comment: 5 pages (including 2 figures

The 108th AAA Group invaded Fortress Europe 27 June 1944

Headquarters and Headquarters Battery 1 08th Antiaircraft Artillery Group, a new organization in the annals of United States military history, has had a rich and important part in the successful prosecution of this Second Great War just ended. Activated 1 March 1942 at Camp Davis, North Carolina, as Headquarters and Headquarters Battery 514th Coast Artillery (Antiaircraft) the Group had had the responsibility for providing demonstration, instruction and maintenance personnel for the Antiaircraft School and Antiaircraft Board until October 1943.https://digicom.bpl.lib.me.us/ww_reg_his/1004/thumbnail.jp

Modulation of Pain with Transcranial Direct Current Stimulation and Diffuse Noxious Inhibitory Controls

Background: While pain is essential for physiological functioning, chronic or pathologic pain is responsible for a major burden of disease in society. Novel approaches to treating acute and chronic pain have employed neuromodulatory tools to target the central and peripheral neural structures that mediate pain. Transcranial direct current stimulation (tDCS), for example, is a safe, non-invasive brain stimulation technique that has been shown in preliminary studies to reduce chronic pain when applied to the primary motor cortex. In contrast to this exogenous neuromodulatory approach, diffuse noxious inhibitory controls (DNIC) refers to endogenous pain regulatory mechanisms that decrease pain following introduction of heterotopic noxious stimuli. This thesis explores whether combining these exogenous and endogenous pain modulation approaches synergistically increases the threshold at which pain is perceived. Methods: We conducted a double-blinded, randomized, placebo-controlled trial with a crossover design to investigate the effects of tDCS and DNIC on pain thresholds in 15 healthy human subjects. Pain thresholds were assessed prior to and following administration of active tDCS, sham tDCS, cold-water-induced DNIC, and combined active tDCS and DNIC. Using magnetic resonance spectroscopy, we examined whether baseline concentrations of brain metabolites such as N-acetylaspartate in pain-related regions of interest were associated with responses to the varying neuromodulatory conditions. Results: Pain thresholds significantly increased following both active tDCS and the DNIC paradigm. These modulatory approaches appeared to have additive effects when combined. Pain threshold increases after active tDCS were positively correlated with baseline levels of N-acetylaspartate, a marker of good neural function, in the anterior cingulate cortex and negatively correlated with baseline levels of glutamine in the thalamus. Conclusions: Combining endogenous pain regulatory mechanisms with exogenous stimulation of the motor cortex can more effectively increase pain thresholds in healthy humans. Future studies should examine whether existing pain therapies may be enhanced with noninvasive brain stimulation and activation of DNIC. They should also assess whether brain metabolite levels can be utilized to predict clinical response to therapeutic interventions

Physics and Applications of Laser Diode Chaos

An overview of chaos in laser diodes is provided which surveys experimental achievements in the area and explains the theory behind the phenomenon. The fundamental physics underpinning this behaviour and also the opportunities for harnessing laser diode chaos for potential applications are discussed. The availability and ease of operation of laser diodes, in a wide range of configurations, make them a convenient test-bed for exploring basic aspects of nonlinear and chaotic dynamics. It also makes them attractive for practical tasks, such as chaos-based secure communications and random number generation. Avenues for future research and development of chaotic laser diodes are also identified.Comment: Published in Nature Photonic

MRI as a viable alternative to CT for 3D surgical planning of cavitary bone tumors

Cavitary bone defects, defined as a volumetric loss of native bone tissue, require accurate preoperative imaging for treatment planning. While CT (computed tomography) has traditionally been the gold standard for segmentation due to its superior resolution of cortical bone, MRI (magnetic resonance imaging) offers unique advantages, particularly in visualizing the soft tissue–bone interface. Furthermore, MRI eliminates the ionizing radiation associated with CT, making it an advantageous alternative, especially in the management of benign and low-grade malignant bone tumors. Despite these advantages, MRI's inherently lower spatial resolution may introduce artifacts, which can complicate segmentation accuracy. This study evaluates the feasibility of MRI as a viable alternative to CT in the preoperative planning of cavitary bone defect treatment. We analyzed CT and MRI scans from 80 patients with benign and locally aggressive primary bone tumors, generating three-dimensional (3D) models through manual segmentation in Mimics, validated using Geomagic Control X. Volumetric differences between the CT- and MRI-derived models were assessed using the Wilcoxon signed-rank test and paired t-test. The mean volumetric difference between MRI and CT scans was 2.68 ± 1.44 %, which was not statistically significant (p = 0.15). Additionally, multiple regression analysis examining sex, age, and diagnosis revealed no significant differences in the 3D model volumes derived from the two imaging modalities (sex: p = 0.51, age: p = 0.98, and diagnosis: p = 0.50). These results support MRI-based segmentation as a reliable, radiation-free alternative to CT, particularly when precise delineation of soft tissue boundaries is critical for surgical planning