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Neuromyelitis optica spectrum disorder (NMOSD) and multiple sclerosis (MS) are inflammatory diseases of the CNS. Overlap in the clinical and MRI features of NMOSD and MS means that distinguishing these conditions can be difficult. With the aim of evaluating the diagnostic utility of MRI features in distinguishing NMOSD from MS, we have conducted a cross-sectional analysis of imaging data and developed predictive models to distinguish the two conditions. NMOSD and MS MRI lesions were identified and defined through a literature search. Aquaporin-4 (AQP4) antibody positive NMOSD cases and age- and sex-matched MS cases were collected. MRI of orbits, brain and spine were reported by at least two blinded reviewers. MRI brain or spine was available for 166/168 (99%) of cases. Longitudinally extensive (OR = 203), “bright spotty” (OR = 93.8), whole (axial; OR = 57.8) or gadolinium (Gd) enhancing (OR = 28.6) spinal cord lesions, bilateral (OR = 31.3) or Gd-enhancing (OR = 15.4) optic nerve lesions, and nucleus tractus solitarius (OR = 19.2), periaqueductal (OR = 16.8) or hypothalamic (OR = 7.2) brain lesions were associated with NMOSD. Ovoid (OR = 0.029), Dawson's fingers (OR = 0.031), pyramidal corpus callosum (OR = 0.058), periventricular (OR = 0.136), temporal lobe (OR = 0.137) and T1 black holes (OR = 0.154) brain lesions were associated with MS. A score-based algorithm and a decision tree determined by machine learning accurately predicted more than 85% of both diagnoses using first available imaging alone. We have confirmed NMOSD and MS specific MRI features and combined these in predictive models that can accurately identify more than 85% of cases as either AQP4 seropositive NMOSD or MS

Neuromyelitis optica spectrum disorders (NMOSD) and multiple sclerosis (MS) show overlap in their clinical features. We performed an analysis of relapses with the aim of determining differences between the two conditions. Cases of NMOSD and age- and sex-matched MS controls were collected from across Australia and New Zealand. Demographic and clinical information, including relapse histories, were recorded using a standard questionnaire. There were 75 cases of NMOSD and 101 MS controls. There were 328 relapses in the NMOSD cases and 375 in MS controls. Spinal cord and optic neuritis attacks were the most common relapses in both NMOSD and MS. Optic neuritis (p < 0.001) and area postrema relapses (P = 0.002) were more common in NMOSD and other brainstem attacks were more common in MS (p < 0.001). Prior to age 30 years, attacks of optic neuritis were more common in NMOSD than transverse myelitis. After 30 this pattern was reversed. Relapses in NMOSD were more likely to be treated with acute immunotherapies and were less likely to recover completely. Analysis by month of relapse in NMOSD showed a trend toward reduced risk of relapse in February to April compared to a peak in November to January (P = 0.065). Optic neuritis and transverse myelitis are the most common types of relapse in NMOSD and MS. Optic neuritis tends to occur more frequently in NMOSD prior to the age of 30, with transverse myelitis being more common thereafter. Relapses in NMOSD were more severe. A seasonal bias for relapses in spring-summer may exist in NMOSD.

This report documents the composite unit life testing (CUALT) of a 20-element hydrophone array. The array was subjected to a CUALT which simulated five years of service life. After CUALT was completed, an autopsy was performed on the array to determine failure modes and mechanisms. This report also documents array design, mission profile, CUALT schedule and measurement data, autopsy results, and failure analysis.... Accelerated life testing, Hydrophone array, Hydrophone reliability.

The efficiency of mechanical clamps applied to the molded boot of the MIL-C-24231 (Portsmouth) underwater connector was investigated. A mission profile for underwater connectors was prepared and used to design laboratory test sequences to evaluate connector leakage. A test connector was designed that incorporated the important features of the Portsmouth connector with the addition of leakage monitors in the construction so that leakage paths in the connector could be identified during test. Construction variables of polyurethane or neoprene boots, both bonded and unbonded, clamp design and shielded or unshielded cable were investigated using factorial experimental design and analysis. A preferred clamped connector configuration was detetmined. Preferred test connectors were manufactured using bonded neoprene boots, shielded cable and Band-It Preform clamps and compared to a standard non-clamped polyurethane connector in accelerated life testing. It was determined that a mechanical clamp inhibits leakage in a connector. Although applying a clamp to a connector does not insure water-tight integrity, it was found that after 32 weeks of accelerated life testing, 78% fewer clamped connectors leaked than the control unclamped connectors. The data also indicated that neoprene and polyurethane bonds degrade with time but connectors made with neoprene molded boots were less likely to leak through a bond interface than those made with polyurethane molded boots.

The mechanical properties of shielded and unshielded submarine cables (MIL-C-915/8E) were investigated to determine the effect of shielding on cable life, performance, and reliability. Ten cables (five shielded and five unshielded) were selected for laboratory evaluation. A mission profile was developed to establish the mechanical stress limits that cables must endure in service and a test sequence designed to measure tensile strength, flexural abrasion endurance, crush resistance, creep under static tension, and performance in a hull-stuffing tube. The results of this program showed that: (1) DSS-2 cable does not have adequate tensile strength and should have a strength member added. DSS-3 and larger cables have adequate tensile strength with or without the shield; (2) Unshielded DSS-3 type cable does not perform satisfactorily in hull-stuffing tubes; (3) Shielding is not required to meet mission profile specifications for cable crush or flexural abrasion resistance; (4) Construction parameters other than shielding can significantly affect mechanical performance of cable; (5) Unshielded cable construction can result in increased reliability since it permits a thicker single-jacket construction; and (6) Unshielded cable construction can reduce the cost of cable by 8 to 20 percent. (Author), See also report dated 11 Nov 80, AD-A093 280.

The mechanical properties of shielded and unshielded submarine cables (MIL-C-915/8E) were investigated to determine the effect of shielding on cable life, performance and reliability. Ten cables, five shielded and five unshielded, were selected for laboratory evaluation. A mission profile was developed to establish the mechanical stress limits cables must endure in service and a test sequence designed to measure tensile strength, flexural abrasion endurance, crush resistance, creep under static tension and performance in a hull stuffing tube. The results of this program showed the following: DSS-2 cable does not have adequate tensile strength and should have a strength member added. DSS-3 and larger cables have adequate tensile strength with and without the shield; Unshielded DSS-3 type cables does not perform satisfactorily in hull stuffing tubes; Shielding is not required to meet Mission Profile specifications for cable crush or flexural abrasion resistance; Construction parameters other than shielding can significantly affect mechanical performance of cable; Unshielded cable construction can result in increased reliability since it permits a thicker single jacket construction; and Unshielded cable construction can reduce the cost of cable by 8% to 20%. (Author)

Previous studies have shown that signal levels on tropospheric scatter links are related to weather conditions along the path. It was found that monthly median signals are correlated with radio refractivity gradients near the ground. Thus, climatological data can be used to improve estimates of basic transmission loss for projected scatter links. The correlations of hourly median signals with refractivity gradients and the surface refractivity are investigated for an over-water and a coastal path and found to be significant. This indicates that shortrange forecasts of scatter-circuit performance over water and some coastal areas can be made using routinely available meteorological data. The question of extending the STARCOM network in the western Pacific using tropospheric scatter links is discussed briefly in the light of these considerations. The possibility of jamming scatter links is examined in a separate appendix (classified). (Author)