Issues Relevant to C-H Activation at Platinum(II): Comparative Studies between Cationic, Zwitterionic, and Neutral Platinum(II) Compounds in Benzene Solution

Cationic late metal systems are being highly scrutinized due to their propensity to mediate so-called electrophilic C-H activation reactions. This contribution compares the reactivity of highly reactive cationic platinum(II) systems with structurally related but neutral species. Our experimental design exploits isostructural neutral and cationic complexes supported by bis(phosphine) ligands amenable to mechanistic examination in benzene solution. The data presented herein collectively suggests that neutral platinum complexes can be equally if not more reactive towards benzene than their cationic counter-parts. Moreover, a number of unexpected mechanistic distinctions between the two systems arise that help to explain their respective reactivity

Plato on Metaphysical Explanation: Does 'Participating' Mean Nothing?

According to Aristotle, Plato's efforts at metaphysical explanation not only fail, they are nonsensical. In particular, Plato's appeals to Forms as metaphysically explanatory of the sensibles that participate in them is "empty talk" since "'participating' means nothing" (Met. 992a28-9). I defend Plato against Aristotle's charge by identifying a particular, substantive model of metaphysical predication as the favored model of Plato's late ontology. The model posits two basic metaphysical predication relations: self-predication and participation. In order to understand the participation relation, it is important first to understand how Plato's Forms are self-predicative paradigms. According to the favored model, Forms are self-predicative paradigms insofar as they are ideal, abstract encoders of structural essences. Sensibles participate in Forms by exemplifying the structures encoded in the Forms. Given plausible conditions on metaphysical explanation, Plato's appeals to abstract Forms as metaphysically explanatory of sensibles is a reasonable competitor for Aristotle's appeals to natural, substantial forms. At the very least, Plato's appeals to a participation relation are not empty

Anti-tumor necrosis factor-alpha therapy during murine Klebsiella pneumoniae bacteremia: increased mortality in the absence of liver injury.

Klebsiella pneumoniae is a leading cause of gram-negative bacterial pneumonia, often resulting in bacteremia concurrent with the localized pulmonary infection. The beneficial role of tumor necrosis factor (TNF)-alpha during pulmonary infection has been well documented; however, consequences of TNF-alpha production during systemic bacterial infection are controversial. A murine model of K. pneumoniae was developed to address this important issue. Liver-associated TNF-alpha mRNA was induced within 30 min after intravenous bacterial inoculation and remained elevated through 6 h before returning to near-baseline at 24 h postinfection. Intravenous K. pneumoniae infection induced liver cellular injury that was completely ablated when mice were pretreated with a neutralizing anti-TNF-alpha antibody. Interestingly, this reduction in liver injury failed to translate into improved survival. Mice receiving anti-TNF-alpha continued to succumb to the infection even out to day 10 postinfection. Bacterial clearance after TNF-alpha neutralization was significantly impaired at later time points during infection. Correlating with impaired bacterial clearance was diminished production of liver-associated MIP-2, MIP-1alpha, MCP-1, and interferon-gamma. Further evidence of diminished antibacterial immune responses was noted when the activational status of splenic natural killer cells in anti-TNF-alpha-treated mice was examined 24 h postinfection. Natural killer cells displayed decreased CD69 expression. Combined, these data indicate that the beneficial effects of TNF-alpha during systemic K. pneumoniae infection outweigh the detrimental effects of TNF-alpha-mediated hepatocyte cellular injury. Anti-TNF-alpha therapy, although preventing liver injury during blood-borne bacterial infection, results in a dampened anti-bacterial host response, resulting in decreased bacterial clearance and overall survival

Faraday rotation maps of disk galaxies

Faraday rotation is one of the most widely used observables to infer the strength and configuration of the magnetic field in the ionised gas of the Milky Way and nearby spiral galaxies. Here we compute synthetic Faraday rotation maps at $z=0$ for a set of disk galaxies from the Auriga high-resolution cosmological simulations, for different observer positions within and outside the galaxy. We find that the strength of the Faraday rotation of our simulated galaxies for a hypothetic observer at the solar circle is broadly consistent with the Faraday rotation seen for the Milky Way. The same holds for an observer outside the galaxy and the observed signal of the nearby spiral galaxy M51. However, we also find that the structure and angular power spectra of the synthetic all-sky Faraday rotation maps vary strongly with azimuthal position along the solar circle. We argue that this variation is a result of the structure of the magnetic field of the galaxy that is dominated by an azimuthal magnetic field ordered scales of several kpc, but has radial and vertical magnetic field components that are only ordered on scales of 1-2 kpc. Because the magnetic field strength decreases exponentially with height above the disk, the Faraday rotation for an observer at the solar circle is dominated by the local environment. This represents a severe obstacle for attempts to reconstruct the global magnetic field of the Milky Way from Faraday rotation maps alone without including additional observables.Comment: 10 pages, 10 figures, accepted by MNRA

Pilots' use of a traffic alert and collision-avoidance system (TCAS 2) in simulated air carrier operations. Volume 1: Methodology, summary and conclusions

Pilots' use of and responses to a traffic alert and collision-avoidance system (TCAS 2) in simulated air carrier line operations are described in Volume 1. TCAS 2 monitors the positions of nearby aircraft by means of transponder interrogation, and it commands a climb or descent when conflicting aircraft are projected to reach an unsafe closest point-of-approach within 20 to 25 seconds. A different level of information about the location of other air traffic was presented to each of three groups of flight crews during their execution of eight simulated air carrier flights. A fourth group of pilots flew the same segments without TCAS 2 equipment. Traffic conflicts were generated at intervals during the flights; many of the conflict aircraft were visible to the flight crews. The TCAS equipment successfully ameliorated the seriousness of all conflicts; three of four non-TCAS crews had hazardous encounters. Response times to TCAS maneuver commands did not differ as a function of the amount of information provided, nor did response accuracy. Differences in flight experience did not appear to contribute to the small performance differences observed. Pilots used the displays of conflicting traffic to maneuver to avoid unseen traffic before maneuver advisories were issued by the TCAS equipment. The results indicate: (1) that pilots utilize TCAS effectively within the response times allocated by the TCAS logic, and (2) that TCAS 2 is an effective collision avoidance device. Volume II contains the appendices referenced in Volume I, providing details of the experiment and the results, and the text of two reports written in support of the program

Pilots' use of a traffic alert and collision-avoidance system (TCAS 2) in simulated air carrier operations. Volume 2: Appendices

Pilots' use of and responses to a traffic alert and collision-avoidance system (TCAS 2) in simulated air carrier line operations are discribed in Volume 1. TCAS 2 monitors the positions of nearby aircraft by means of transponder interrogation, and it commands a climb or descent which conflicting aircraft are projected to reach an unsafe closest point-of-approach within 20 to 25 seconds. A different level of information about the location of other air traffic was presented to each of three groups of flight crews during their execution of eight simulated air carrier flights. A fourth group of pilots flew the same segments without TCAS 2 equipment. Traffic conflicts were generated at intervals during the flights; many of the conflict aircraft were visible to the flight crews. The TCAS equipment successfully ameliorated the seriousness of all conflicts; three of four non-TCAS crews had hazardous encounters. Response times to TCAS maneuver commands did not differ as a function of the amount of information provided, nor did response accuracy. Differences in flight experience did not appear to contribute to the small performance differences observed. Pilots used the displays of conflicting traffic to maneuver to avoid unseen traffic before maneuver advisories were issued by the TCAS equipment. The results indicate: (1) that pilots utilize TCAS effectively within the response times allocated by the TCAS logic, and (2) that TCAS 2 is an effective collision avoidance device. Volume 2 contains the appendices referenced in Volume 1, providing details of the experiment and the results, and the text of two reports written in support of the program