A corrosion control manual for rail rapid transit

In 1979, during the planning stage of the Metropolitan Dade County Transit System, the need was expressed for a corrosion control manual oriented to urban rapid transit system use. This manual responds to that need. The objective of the manual is to aid rail rapid transit agencies by providing practical solutions to selected corrosion problems. The scope of the manual encompasses corrosion problems of the facilities of rapid transit systems: structures and tracks, platforms and stations, power and signals, and cars. It also discusses stray electric current corrosion. Both design and maintenance solutions are provided for each problem. Also included are descriptions of the types of corrosion and their causes, descriptions of rapid transit properties, a list of corrosion control committees and NASA, DOD, and ASTM specifications and design criteria to which reference is made in the manual. A bibliography of papers and excerpts of reports and a glossary of frequency used terms are provided

4-aminopyridine toxicity: a case report and review of the literature.

INTRODUCTION: 4-Aminopyridine (4-AP) selectively blocks voltage-gated potassium channels, prolongs the action potential, increases calcium influx, and subsequently, enhances interneuronal and neuromuscular synaptic transmission. This medication has been studied and used in many disease processes hallmarked by poor neuronal transmission in both the central and peripheral nervous systems including: multiple sclerosis (MS), spinal cord injuries (SCI), botulism, Lambert-Eaton syndrome, and myasthenia gravis. It has also been postulated as a potential treatment of verapamil toxicity and reversal agent for anesthesia-induced neuromuscular blockade. To date, there have been limited reports of either intentional or accidental 4-AP toxicity in humans. Both a case of a patient with 4-AP toxicity and review of the literature are discussed, highlighting commonalities observed in overdose. CASE REPORT: A 37-year-old man with progressive MS presented with diaphoresis, delirium, agitation, and choreathetoid movements after a presumed 4-AP overdose. 4-AP concentration at 6 h was 140 ng/mL. With aggressive benzodiazepine administration and intubation, he recovered uneventfully. DISCUSSION: The commonalities associated with 4-AP toxicity conforms to what is known about its mechanism of action combining cholinergic features including diaphoresis, altered mental status, and seizures with dopamine-related movement abnormalities including tremor, choreoathetosis, and dystonia. Management of patients poisoned by 4-AP centers around good supportive care with definitive airway management and controlling CNS hyperexcitability aggressively with gamma-aminobutyric acid agonist agents. Adjunctive use of dopamine antagonists for extrapyramidal effects after sedation is a treatment possibility. As 4-aminopyridine recently received Federal Drug Administration approval for the treatment of ambulation in patients with MS, physicians should be keenly aware of its presentation, mechanism of action, and management in overdose

Stabilizing Even-Parity Chiral Superconductivity in Sr2_2RuO4_4

Strontium ruthenate (Sr$_2$RuO$_4$) has long been thought to host a spin-triplet chiral $p$-wave superconducting state. However, the singletlike response observed in recent spin-susceptibility measurements casts serious doubts on this pairing state. Together with the evidence for broken time-reversal symmetry and a jump in the shear modulus $c_{66}$ at the superconducting transition temperature, the available experiments point towards an even-parity chiral superconductor with $k_z(k_x\pm ik_y)$-like $E_g$ symmetry, which has consistently been dismissed based on the quasi-two-dimensional electronic structure of Sr$_2$RuO$_4$. Here, we show how the orbital degree of freedom can encode the two-component nature of the $E_g$ order parameter, allowing for a local orbital-antisymmetric spin-triplet state that can be stabilized by on-site Hund's coupling. We find that this exotic $E_g$ state can be energetically stable once a complete, realistic three-dimensional model is considered, within which momentum-dependent spin-orbit coupling terms are key. This state naturally gives rise to Bogoliubov Fermi surfaces.Comment: 6+10 pages, 5 figure

Augmenting Cyber Defender Performance and Workload through Sonified Displays

AbstractMilitary cyber operations occur in a cognitively intense and stressful environment, and consequently, operator burnout is relatively high when compared to other operational environments. There is a distinct need for new and innovative ways to augment operator capabilities, increase performance, manage workload, and decrease stress in cyber. In this study, we assessed how a sonified display could address these requirements. Sonification has been demonstrated to be a useful method for presenting temporal data in multiple domains. Participants in the experiment were tasked with detecting evidence of a cyber attack in a simulated task environment modeled after “Wireshark,” a popular packet analyzer program. As they completed the task, participants either did or did not have access to a redundant sonified display that provided an auditory representation of the textual data presented in Wireshark. We expected that the sonified display would improve operator performance and reduce workload and stress. However, our results did not support those expectations – access to the sonification did not affect performance, workload, or stress. Our findings highlight the need for continued research into effective methods for augmenting cyber operator capabilities

Subduction beneath Laurentia modified the eastern North American cratonic edge : Evidence from P wave and S wave tomography

Funding Information: NERC Doctoral Training Partnership: Science and Solutions for a Changing Planet and Leverhulme Trust Acknowledgments A.B. is funded by the NERC Doctoral Training Partnership: Science and Solutions for a Changing Planet. I.B. is funded by the Leverhulme Trust. F.D. acknowledges funding from NSERC through their Discovery grants and Canada Research Chairs program. We thank J. VanDecar for use of his tomographic inversion and MCCC codes. SAC [Helffrich et al., 2013] and GMT [Wessel and Smith, 1995] software were also used to process seismic data obtained from the IRIS DMC and from the Canadian National Data Centre (Natural Resources Canada). A digital supplement is also available to download containing models and the processed relative arrival‐time data set, additional information is available from A.B. (email: [email protected]). Discussing the implications of our tomographic results with S. Goes and A. Hynes provided great motivation for this manuscript. Two anonymous reviewers helped clarify our interpretations.Peer reviewedPublisher PD

Mass-luminosity relation for FGK main sequence stars: metallicity and age contributions

The stellar mass-luminosity relation (MLR) is one of the most famous empirical "laws", discovered in the beginning of the 20th century. MLR is still used to estimate stellar masses for nearby stars, particularly for those that are not binary systems, hence the mass cannot be derived directly from the observations. It's well known that the MLR has a statistical dispersion which cannot be explained exclusively due to the observational errors in luminosity (or mass). It is an intrinsic dispersion caused by the differences in age and chemical composition from star to star. In this work we discuss the impact of age and metallicity on the MLR. Using the recent data on mass, luminosity, metallicity, and age for 26 FGK stars (all members of binary systems, with observational mass-errors <= 3%), including the Sun, we derive the MLR taking into account, separately, mass-luminosity, mass-luminosity-metallicity, and mass-luminosity-metallicity-age. Our results show that the inclusion of age and metallicity in the MLR, for FGK stars, improves the individual mass estimation by 5% to 15%.Comment: 7 pages, 4 figures, 1 table, accepted in Astrophysics and Space Scienc