Anthropogenic Space Weather

Anthropogenic effects on the space environment started in the late 19th century and reached their peak in the 1960s when high-altitude nuclear explosions were carried out by the USA and the Soviet Union. These explosions created artificial radiation belts near Earth that resulted in major damages to several satellites. Another, unexpected impact of the high-altitude nuclear tests was the electromagnetic pulse (EMP) that can have devastating effects over a large geographic area (as large as the continental United States). Other anthropogenic impacts on the space environment include chemical release ex- periments, high-frequency wave heating of the ionosphere and the interaction of VLF waves with the radiation belts. This paper reviews the fundamental physical process behind these phenomena and discusses the observations of their impacts.Comment: 71 pages, 35 figure

Anterior cervical fusion versus minimally invasive posterior keyhole decompression for cervical radiculopathy

Background: Treatment modalities for degenerative cervical spine disease are widely debated and refined as new surgical techniques are developed. The current case series compares two common cervical spine procedures, anterior cervical discectomy and fusion (ACDF) and minimally invasive posterior keyhole foraminotomy (MIPKF). The decision making process of the two surgical approaches is discussed, and the long term outcomes are presented. Methods: A retrospective chart review of surgical patients having either an ACDF or MIPKF with an extensive chart review. Over 570 patient charts were identified and reviewed between 1994 and 2011. After exclusion, a total of 268 patients were identified in the ACDF group, and 112 patients were identified in the MIPKF group. Primary outcome measurement was the need for any reoperation, whether at the same level or adjacent levels due to recurrence of disease or adjacent level disease. Results: An average follow-up of 11.8 (±3.0) years in the ACDF group and 6.4 (±4.4) years in the MIPKF group was determined over a 17 year period. There was a reoperation rate of 2.6% in the ACDF group and 2.7% in the MIPKF group during the 17 year time period. Conclusion: ACDF has been demonstrated to be an effective surgical procedure in treating degenerative spine disease in patients with radiculopathy and/or myelopathy. However, in a population with isolated radiculopathy and radiological imaging confirming an anterolateral disc or osteophyte complex, the MIPKF can provide similar results without the associated risks that accompany an anterior cervical spine fusion

β-Adrenergic modulation of emotional memory-evoked human amygdala and hippocampal responses

Human emotional experience is typically associated with enhanced episodic memory. We have used functional magnetic resonance imaging to demonstrate that successful encoding of emotional, compared to neutral, verbal stimuli evokes increased human amygdala responses. Items that evoke amygdala activation at encoding evoke greater hippocampal responses at retrieval compared to neutral items. Administration of the β-adrenergic antagonist propranolol at encoding abolishes the enhanced amygdala encoding and hippocampal retrieval effects, despite propranolol being no longer present at retrieval. Thus, memory-related amygdala responses at encoding and hippocampal responses at recognition for emotional items depend on β-adrenergic engagement at encoding. Our results suggest that human emotional memory is associated with a β-adrenergic-dependent modulation of amygdala-hippocampal interactions