7,068 research outputs found

    K2 observations of the pulsating subdwarf B star EQ Piscium: an sdB+dM binary

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    K2, the two-wheel mission of the Kepler space telescope, observed the pulsating subdwarf B star EQ Psc during engineering tests in 2014 February. In addition to a rich spectrum of g-mode pulsation frequencies, the observations demonstrate a light variation with a period of 19.2 h and a full amplitude of 2%. We suggest that this is due to reflection from a cool companion, making EQ\,Psc the longest-period member of some 30 binaries comprising a hot subdwarf and a cool dwarf companion (sdB+dM), and hence useful for exploring the common-envelope ejection mechanism in low-mass binaries.Comment: Accepted for publication in MNRA

    Wellness Lessons From Transportation Companies, Research Report WP 11-01

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    The purpose of this report is to describe wellness programs and offer two suggestions for improving how they are delivered to commercial drivers and operators. It is not a large sample empirical study from which generalizations can be made. Rather, the Mineta Transportation Institute commissioned brief case studies of transportation companies to show what several organizations have done. Stress, nicotine use, sleep apnea, obesity and lack of information are significant barriers to wellness in commercial drivers/operators. Many wellness programs ask the individual driver/operator to lose weight; exercise more; and monitor blood pressure, glucose, cholesterol and other such indicators of health. However, little is done to change the environment or adopt structural interventions such as forbidding nicotine use, as is possible in 20 states. Other structural interventions include those possible at the levels of the company and community, including access to healthy food rather than the junk food drivers often can find on the road. At the societal level, more public transit that gets people walking and out of their cars, cities designed for people to walk and cycle in rather than drive from work to a sprawling suburb, and encouraging food manufacturers to make healthy food (rather than a toxic mix of sodium, fat and sugar to boost one’s craving for a particular food) are just a few measures that could improve the health and well being of the public. The Union Pacific Corporation (rail transportation), and Con-way Freight (trucking) are included because they were willing to share information and are large publicly traded companies. The Utah Transit Authority (UTA) is included because other transit authorities recommended it to the authors, as it has a long history in wellness as part of local government and it too chose to participate. Two issues are discussed: the first is the importance of using the mitigation of erectile dysfunction in the promotion of wellness programs to commercial drivers/operators and the second issue is to urge employers to consider banning tobacco use, both on and off the job, where legal

    A search for electron cyclotron maser emission from compact binaries

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    Unipolar induction (UI) is a fundamental physical process, which occurs when a conducting body transverses a magnetic field. It has been suggested that UI is operating in RX J0806+15 and RX J1914+24, which are believed to be ultra-compact binaries with orbital periods of 5.4 min and 9.6 min respectively. The UI model predicts that those two sources may be electron cyclotron maser sources at radio wavelengths. Other systems in which UI has been predicted to occur are short period extra-solar terrestrial planets with conducting cores. If UI is present, circularly polarised radio emission is predicted to be emitted. We have searched for this predicted radio emission from short period binaries using the VLA and ATCA. In one epoch we find evidence for a radio source, coincident in position with the optical position of RX J0806+15. Although we cannot completely exclude that this is a chance alignment between the position of RX J0806+15 and an artifact in the data reduction process, the fact that it was detected at a significance level of 5.8 sigma and found to be transient, suggests that it is more likely that RX J0806+15 is a transient radio source. We find an upper limit on the degree of circular polarisation to be ~50%. The inferred brightness temperature exceeds 10^18 K, which is too high for any known incoherent process, but is consistent with maser emission and UI being the driving mechanism. We did not detect radio emission from ES Cet, RX J1914+24 or Gliese 876.Comment: Accepted for publication MNRA

    An Approach to the Synthesis of Aspergillic Acid

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    Aspergillic acid, the antibiotic isolated from cultures of the mould Aspergillus flavus, was shown by Dutcher end Wintersteiner to have structure (I) or (IA). Later, Dunn, Newbold and Spring identified the side-chains and showed that aspergillic acid must be either (I; R= Bus, R' = Bui) or (I; R = Bui, R' = Bus). The investigations described in this Thesis were directed towards establishing methods for the synthesis of pyrazine cyclic hydroxamic acids with the synthesis of aspergillic acid as the ultimate objective. Reduction of aspergillic acid gives deoxyaspergillic acid (II), a 2-hydroxy-3:6-disubstituted pyrazine. Thus it appeared possible that oxidation of a suitably substituted pyrazine would lead to a synthesis of aspergillic acid. This route was shown to be impracticable by Baxter, Newbold and Spring who found that when a 2-ethoxy-3:6-disubstituted pyrazine was oxidised, oxidation occurred at the nitrogen remote from the ethoxy group and hence hydrolysis to give a hydroxyl group in the 2-position gave a compound which was not a hydroxamic acid. Although the direct oxidation method had proved unsuccessful for a synthesis of aspergillic acid there was a possibility that it could be used to prepare a pyrazine cyclic hydroxamic acid by the following route:- The oxide (IV) was obtained in low yield. The scheme however, had to be abandoned when difficulty was experienced in hydrolysing the nitrile groups of the oxide as a preliminary to the formation of the required hydroxyl groups. An account is given of the experiments with aminoiminosuecinonitrile (III) which extend its application as a synthetic intermediate. An entirely different approach, namely the formation of the pyrazine ring by ring-closure of an acyclic hydroxamic acid proved more successful. The following general method for the synthesis of 3:6-disubstituted pyrazine cyclic hydroxsmic acids has been developed. This method was applied successfully to three cases including that of a homologue of aspergillic acid (R = R'' = Et) which was isolated in very low yield. The synthesis of one of the possible structures of aspergillic acid (I; R = Bui, R' = Bus) was attempted by this route. After a number of methods for the synthesis of unsaturated alphabeta-aldehydes had been investigated, the required Schiff's base was prepared as follows: A satisfactory cyclisation of the Schiff's base to give (I; R = Bui, R' = Bus) was not achieved. An ultra-violet absorption spectrum showed that the cyclic acid had been formed but only to the extent of 30% of a resinous reaction product isolated in low yield. The difficulties encountered at this ring-closure stage are discussed. An alternative route to 3:6-disubstituted pyrazine cyclic hydroxamic acids has been developed. An a-keto-hydroxamic acid is condensed with an aminoketone to form the cyclic acid in one step thus: In the first instance pyruvchydroxamyl chloride was converted into the bisulphite compound of pyruvohydroxamic acid (V; R = Me). This was condensed with aminoacetone (VI; R' = Me) to give an aspergillic acid homologue (VII; R = R' = Me) in good yield. The structure of the cyclic acid was completely defined when reduction gave 2-hydroxy-3:6-dimethylpyrazine, a known compound. Application of the above method to the aspergillic acid case (VII; R = Bus, R' = Bui) proved less successful. A cyclic acid was not formed when the bisulphite compound of the alpha-keto-hydroxamic acid (V; R = Bus) was treated with the aminoketone (VI; R' = Bui). An experiment in which the alpha-keto-hydroxamic acid was formed by hydrolysis of the hydroxamyl chloride (VIII) with sodium acetate in acetic acid showed more promise. The acid was not isolated but treated directly with the aminoketone. A non-crystalline reaction product had an ultra-violet absorption spectrum from which it was evident that it contained a small proportion of the cyclic acid (VII; R = Bus, R' = Bui)
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