Confirming Fundamental Parameters of the Exoplanet Host Star epsilon Eridani Using the Navy Optical Interferometer

We measured the angular diameter of the exoplanet host star epsilon Eridani using the Navy Optical Interferometer. We determined its physical radius, effective temperature, and mass by combining our measurement with the star's parallax, photometry from the literature, and the Yonsei-Yale isochrones (Yi et al. 2001), respectively. We used the resulting stellar mass of 0.82 +/- 0.05 M_Sun plus the mass function from Benedict et al. (2006) to calculate the planet's mass, which is 1.53 +/- 0.22 M_Jupiter. Using our new effective temperature, we also estimated the extent of the habitable zone for the system.Comment: Accepted for publication in The Astrophysical Journa

Two-Band-Type Superconducting Instability in MgB2

Using the tight-binding method for the $\pi$-bands in MgB$_2$, the Hubbard on-site Coulomb interaction on two inequivalent boron $p_z$-orbitals is transformed into expressions in terms of $\pi$-band operators. For scattering processes relevant to the problemin which a wave vector {\bf q} is parallel to $\hat{z}$, it is found to take a relatively simple form consisting of intra-band Coulomb scattering, interband pair scattering etc. with large constant coupling constants. This allows to get a simple expression for the amplitude of interband pair scattering between two $\pi$-bands, which diverges if the interband polarization function in it becomes large enough.The latter was approximately evaluated and found to be largely enhanced in the band structure in MgB$_2$. These results lead to a divergent interband pair scattering, meaning two-band-type superconducting instability with enhanced $T_c$. Adding a subsidiary BCS attractive interaction in each band into consideration, a semi-quantitative gap equation is given, and $T_c$ and isotope exponent $\alpha$ are derived. The present instability is asserted to be the origin of high $T_c$ in MgB$_2$.Comment: 4 pages, to be published in J. Phys. Soc. Jpn. vol. 70, No.

Essential Role of the Iron-Regulated Outer Membrane Receptor FauA in Alcaligin Siderophore-Mediated Iron Uptake in Bordetella Species

Phenotypic analysis using heterologous host systems localized putative Bordetella pertussis ferric alcaligin transport genes and Fur-binding sequences to a 3.8-kb genetic region downstream from the alcR regulator gene. Nucleotide sequencing identified a TonB-dependent receptor family homolog gene, fauA, predicted to encode a polypeptide with high amino acid sequence similarity with known bacterial ferric siderophore receptors. In Escherichia coli, the fauA genes of both B. pertussis and Bordetella bronchiseptica directed the production of a 79-kDa polypeptide, approximating the predicted size of the mature FauA protein. B. bronchiseptica fauA insertion mutant BRM17 was unable to utilize ferric alcaligin, and in complementation analyses ferric alcaligin utilization was restored to this mutant by supplying the wild-type fauA gene in trans. Mutant BRM18, carrying a nonpolar in-frame fauA deletion mutation, was defective in ferric alcaligin utilization and 55Fe-ferric alcaligin uptake and no longer produced a 79-kDa iron-regulated outer membrane protein. In complementation analyses, BRM18 merodiploids bearing the wild-type fauA gene in trans regained ferric alcaligin siderophore transport and utilization functions and produced the 79-kDa protein. Analysis of a plasmid-borne fauA-lacZ operon fusion confirmed that fauA is subject to iron regulation at the transcriptional level and that cis-acting transcriptional control elements mediating fauA iron repressibility reside within the 3.8-kb PstI fauA DNA region. Moreover, expression of the fauA-lacZ fusion gene under iron starvation conditions was shown to be alcR dependent. FauA is a 79-kDa iron-regulated outer membrane receptor protein required for transport and utilization of ferric alcaligin siderophore complexes by Bordetella species. Originally published Journal of Bacteriology, Vol. 181, No. 19, Oct 199

Reported frequency of physical activity in a large epidemiological study: relationship to specific activities and repeatability over time

BACKGROUND How overall physical activity relates to specific activities and how reported activity changes over time may influence interpretation of observed associations between physical activity and health. We examine the relationships between various physical activities self-reported at different times in a large cohort study of middle-aged UK women. METHODS At recruitment, Million Women Study participants completed a baseline questionnaire including questions on frequency of strenuous and of any physical activity. About 3 years later 589,896 women also completed a follow-up questionnaire reporting the hours they spent on a range of specific activities. Time spent on each activity was used to estimate the associated excess metabolic equivalent hours (MET-hours) and this value was compared across categories of physical activity reported at recruitment. Additionally, 18,655 women completed the baseline questionnaire twice, at intervals of up to 4 years; repeatability over time was assessed using the weighted kappa coefficient (κweighted) and absolute percentage agreement. RESULTS The average number of hours per week women reported doing specific activities was 14.0 for housework, 4.5 for walking, 3.0 for gardening, 0.2 for cycling, and 1.4 for all strenuous activity. Time spent and the estimated excess MET-hours associated with each activity increased with increasing frequency of any or strenuous physical activity reported at baseline (tests for trend, P < 0.003), although the associations for housework were by far the weakest (Spearman correlations, 0.01 and -0.03 respectively for housework, and 0.11-0.37 for all other activities). Repeatability of responses to physical activity questions on the baseline questionnaire declined significantly over time. For strenuous activity, absolute agreement was 64% (κweighted = 0.71) for questionnaires administered less than 6 months apart, and 52% (κweighted = 0.51) for questionnaires more than 2 years apart. Corresponding values for any physical activity were 57% (κweighted = 0.67) and 47% (κweighted = 0.58). CONCLUSIONS In this cohort, responses to simple questions on the frequency of any physical activity and of strenuous activity asked at baseline were associated with hours spent on specific activities and the associated estimated excess MET-hours expended, reported 3 years later. The weakest associations were with housework. Agreement for identical questions asked on two occasions about the frequency of physical activity decreased over time.This work was supported by public funds from Cancer Research UK and the UK Medical Research Council

Using functional near infrared spectroscopy to assess cognitive performance of UAV sensor operators during route scanning

The composition of UAV (Unmanned Aerial Vehicle) crew will sometimes define roles specific to tasks associated with the Ground Control Station (GCS). The sensor operator task is specific to both the type of platform and GCS they are operating, but in many instances the role of this operator is critical in determining mission success. In order to assess mission effectiveness we applied human performance measures that focussed on neurological brain imaging techniques and other physiological biomarkers in conjunction with behavioral data acquired from the sensor operator task. In the execution of the experiment, this included such tasks as route scanning, target detection and positive identification, and the tracking of identified targets. Within the scope of this paper, we reported the preliminary results for the route scanning task. Over the duration of three trials brain activity measures from the prefrontal cortex region were acquired via functional near infrared spectroscopy (fNIRS) in this research study. As the trials progressed, there was a significant difference between low and high performers on the route scanning task as determined by specific biomarkers, namely oxygenated haemoglobin. These findings support previous studies and indicates the benefits of applying neurophysiological measures in order to gain further objective insight into human cognitive performance. The use of fNIRS in this context is also discussed in terms of providing a key benefit in dynamically evaluating human performance in parallel with personalized training for UAV operators

Modelling approaches for relating effects of change in river flow to populations of Atlantic salmon and brown trout

Modelling approaches for relating discharge to the biology of Atlantic salmon, Salmo salar L., and brown trout, Salmo trutta L., growing in rivers are reviewed. Process-based and empirical models are set within a common framework of input of water flow and output of characteristics of fish, such as growth and survival, which relate directly to population dynamics. A continuum is envisaged incorporating various contributions of process and empirical structure as practical and appropriate to specific goals. This framework is compared with, and shown to differ from, approaches whose output is in the form of quantity and form of habitat (or usable area) based on its frequency of use by fish, which then is assumed to have some relationship with fish performance. A simple conceptual modeling approach is also developed to relate water flow to fish population characteristics to assess the likelihood of simple relationships between flow and usable area thresholds. Basic predictions of the model are tested against empirical data from a long-term individual-based study of juvenile S. salar and resident brook trout, Salvelinus fontinalis (Mitchell), in West Brook, Massachusetts. For this system, growth rates of both species increased linearly with flow during spring, summer and autumn months and bore no relation to Q95 or wetted-width discontinuities. Winter is identified as a season during which water might be abstracted most safely, but cautiously given sparse knowledge of wild salmonid fish at this time of year. These results, together with the fundamental conceptual problems inherent in usable area-based approaches, suggest that models that relate directly to fish performance outcomes may be more robust as a basis for flow prescriptions. However, this utility will depend strongly on our ability to generalize from a limited set of empirical studies and to use the results of these studies of management actions to inform and improve future models

Modelling approaches for relating effects of change in river flow to populations of Atlantic salmon and brown trout

Modelling approaches for relating discharge to the biology of Atlantic salmon, Salmo salar L., and brown trout, Salmo trutta L., growing in rivers are reviewed. Process-based and empirical models are set within a common framework of input of water flow and output of characteristics of fish, such as growth and survival, which relate directly to population dynamics. A continuum is envisaged incorporating various contributions of process and empirical structure as practical and appropriate to specific goals. This framework is compared with, and shown to differ from, approaches whose output is in the form of quantity and form of habitat (or usable area) based on its frequency of use by fish, which then is assumed to have some relationship with fish performance. A simple conceptual modeling approach is also developed to relate water flow to fish population characteristics to assess the likelihood of simple relationships between flow and usable area thresholds. Basic predictions of the model are tested against empirical data from a long-term individual-based study of juvenile S. salar and resident brook trout, Salvelinus fontinalis (Mitchell), in West Brook, Massachusetts. For this system, growth rates of both species increased linearly with flow during spring, summer and autumn months and bore no relation to Q95 or wetted-width discontinuities. Winter is identified as a season during which water might be abstracted most safely, but cautiously given sparse knowledge of wild salmonid fish at this time of year. These results, together with the fundamental conceptual problems inherent in usable area-based approaches, suggest that models that relate directly to fish performance outcomes may be more robust as a basis for flow prescriptions. However, this utility will depend strongly on our ability to generalize from a limited set of empirical studies and to use the results of these studies of management actions to inform and improve future models

Time Delay Interferometry for LISA with one arm dysfunctional

In order to attain the requisite sensitivity for LISA - a joint space mission of the ESA and NASA- the laser frequency noise must be suppressed below the secondary noises such as the optical path noise, acceleration noise etc. By combining six appropriately time-delayed data streams containing fractional Doppler shifts - a technique called time delay interferometry (TDI) - the laser frequency noise may be adequately suppressed. We consider the general model of LISA where the armlengths vary with time, so that second generation TDI are relevant. However, we must envisage the possibility, that not all the optical links of LISA will be operating at all times, and therefore, we here consider the case of LISA operating with two arms only. As shown earlier in the literature, obtaining even approximate solutions of TDI to the general problem is very difficult. Since here only four optical links are relevant, the algebraic problem simplifies considerably. We are then able to exhibit a large number of solutions (from mathematical point of view an infinite number) and further present an algorithm to generate these solutions