Results of recent NASA research on low-speed aerodynamic characteristics of supersonic cruise aircraft

The relatively low values of lift-curve slope produced by highly swept arrow wings, coupled with the low scrape angle of the fuselage, resulted in relatively low values of take-off and approach lift coefficients. Through the use of more efficient high-lift systems and the application of propulsive-lift concepts, it is possible to optimize the engine-airframe design for maximum range potential and also to provide good low-speed performance. Nose strakes provide significant improvements in directional stability characteristics and the use of a propulsive lateral control system provides a solution to problems associated with inherently low levels of lateral control

Population Dynamics in the Penna Model

We build upon the recent steady-state Penna model solution, Phys.Rev.Lett. 89, 288103 (2002), to study the population dynamics within the Penna model. We show, that any perturbation to the population can be broken into a collection of modes each of which decay exponentially with its respective time constant. The long time behaviour of population is therefore likely to be dominated by the modes with the largest time constants. We confirm our analytical approach with simulation data.Comment: 6 figure

Summary of information on low-speed lateral-directional derivatives due to rate of change of sideslip beta prime

The results presented show that the magnitudes of the aerodynamic stability derivatives due to rate of change of sideslip become quite large at high angles of attack for swept- and delta-wing configurations, and that such derivatives have large effects on the calculated dynamic stability of these configurations at high angles of attack. The wind-tunnel test techniques used to measure the beta prime derivatives and various approaches used to predict them are discussed. Both the conventional oscillating-airfoil theory and the lag-of-the-sidewash theory are shown to be inadequate for predicting the vertical-tail contribution to the acceleration-in-sideslip derivative; a flow-field-lag theory, which is discussed, appears to give qualitative agreement with experimental data for a current twin-jet fighter configuration

Wind-tunnel free-flight investigation of a model of a spin-resistant fighter configuration

An investigation was conducted to provide some insight into the features affecting the high-angle-of-attack characteristics of a high-performance twin-engine fighter airplane which in operation has exhibited excellent stall characteristics with a general resistance to spinning. Various techniques employed in the study included wind-tunnel free-flight tests, flow-visualization tests, static force tests, and dynamic (forced-oscillation) tests. In addition to tests conducted on the basic configuration tests were made with the wing planform and the fuselage nose modified. The results of the study showed that the model exhibited good dynamic stability characteristics at angles of attack well beyond that for wing stall. The directional stability of the model was provided by the vertical tail at low and moderate angles of attack and by the fuselage forebody at high angles of attack. The wing planform was found to have little effect on the stability characteristics at high angles of attack. The tests also showed that although the fuselage forebody produced beneficial contributions to static directional stability at high angles of attack, it also produced unstable values of damping in yaw. Nose strakes located in a position which eliminated the beneficial nose contributions produced a severe directional divergence

The Orbital Solution and Spectral Classification of the High-Mass X-Ray Binary IGR J01054-7253 in the Small Magellanic Cloud

We present X-ray and optical data on the Be/X-ray binary (BeXRB) pulsar IGR J01054-7253 = SXP11.5 in the Small Magellanic Cloud (SMC). Rossi X-ray Timing Explorer (RXTE) observations of this source in a large X-ray outburst reveal an 11.483 +/- 0.002s pulse period and show both the accretion driven spin-up of the neutron star and the motion of the neutron star around the companion through Doppler shifting of the spin period. Model fits to these data suggest an orbital period of 36.3 +/- 0.4d and Pdot of (4.7 +/- 0.3) x 10^{-10} ss^{-1}. We present an orbital solution for this system, making it one of the best described BeXRB systems in the SMC. The observed pulse period, spin-up and X-ray luminosity of SXP11.5 in this outburst are found to agree with the predictions of neutron star accretion theory. Timing analysis of the long-term optical light curve reveals a periodicity of 36.70 +/- 0.03d, in agreement with the orbital period found from the model fit to the X-ray data. Using blue-end spectroscopic observations we determine the spectral type of the counterpart to be O9.5-B0 IV-V. This luminosity class is supported by the observed V-band magnitude. Using optical and near-infrared photometry and spectroscopy, we study the circumstellar environment of the counterpart in the months after the X-ray outburst.Comment: 12 pages, 13 figures and 3 tables. This paper has been accepted for publication in MNRA

Diquat Derivatives: Highly Active, Two-Dimensional Nonlinear Optical Chromophores with Potential Redox Switchability

In this article, we present a detailed study of structure−activity relationships in diquaternized 2,2′-bipyridyl (diquat) derivatives. Sixteen new chromophores have been synthesized, with variations in the amino electron donor substituents, π-conjugated bridge, and alkyl diquaternizing unit. Our aim is to combine very large, two-dimensional (2D) quadratic nonlinear optical (NLO) responses with reversible redox chemistry. The chromophores have been characterized as their PF_6^− salts by using various techniques including electronic absorption spectroscopy and cyclic voltammetry. Their visible absorption spectra are dominated by intense π → π^* intramolecular charge-transfer (ICT) bands, and all show two reversible diquat-based reductions. First hyperpolarizabilities β have been measured by using hyper-Rayleigh scattering with an 800 nm laser, and Stark spectroscopy of the ICT bands affords estimated static first hyperpolarizabilities β_0. The directly and indirectly derived β values are large and increase with the extent of π-conjugation and electron donor strength. Extending the quaternizing alkyl linkage always increases the ICT energy and decreases the E_(1/2) values for diquat reduction, but a compensating increase in the ICT intensity prevents significant decreases in Stark-based β_0 responses. Nine single-crystal X-ray structures have also been obtained. Time-dependent density functional theory clarifies the molecular electronic/optical properties, and finite field calculations agree with polarized HRS data in that the NLO responses of the disubstituted species are dominated by ‘off-diagonal’ β_(zyy) components. The most significant findings of these studies are: (i) β_0 values as much as 6 times that of the chromophore in the technologically important material (E)-4′-(dimethylamino)-N-methyl-4-stilbazolium tosylate; (ii) reversible electrochemistry that offers potential for redox-switching of optical properties over multiple states; (iii) strongly 2D NLO responses that may be exploited for novel practical applications; (iv) a new polar material, suitable for bulk NLO behavior

Evolution of Linear Absorption and Nonlinear Optical Properties in V-Shaped Ruthenium(II)-Based Chromophores

In this article, we describe a series of complexes with electron-rich cis-{Ru^(II)(NH_3)_4}^(2+) centers coordinated to two pyridyl ligands bearing N-methyl/arylpyridinium electron-acceptor groups. These V-shaped dipolar species are new, extended members of a class of chromophores first reported by us (Coe, B. J. et al. J. Am. Chem. Soc. 2005, 127, 4845−4859). They have been isolated as their PF_6− salts and characterized by using various techniques including ^1H NMR and electronic absorption spectroscopies and cyclic voltammetry. Reversible Ru^(III/II) waves show that the new complexes are potentially redox-switchable chromophores. Single crystal X-ray structures have been obtained for four complex salts; three of these crystallize noncentrosymmetrically, but with the individual molecular dipoles aligned largely antiparallel. Very large molecular first hyperpolarizabilities β have been determined by using hyper-Rayleigh scattering (HRS) with an 800 nm laser and also via Stark (electroabsorption) spectroscopic studies on the intense, visible d → π^* metal-to-ligand charge-transfer (MLCT) and π → π^* intraligand charge-transfer (ILCT) bands. The latter measurements afford total nonresonant β_0 responses as high as ca. 600 × 10^(−30) esu. These pseudo-C_(2v) chromophores show two substantial components of the β tensor, β_(zzz) and β_(zyy), although the relative significance of these varies with the physical method applied. According to HRS, β_(zzz) dominates in all cases, whereas the Stark analyses indicate that β_(zyy) is dominant in the shorter chromophores, but β_(zzz) and β_(zyy) are similar for the extended species. In contrast, finite field calculations predict that β_(zyy) is always the major component. Time-dependent density functional theory calculations predict increasing ILCT character for the nominally MLCT transitions and accompanying blue-shifts of the visible absorptions, as the ligand π-systems are extended. Such unusual behavior has also been observed with related 1D complexes (Coe, B. J. et al. J. Am. Chem. Soc. 2004, 126, 3880−3891)

Applying Contemporary Management Principles to Implementing and Evaluating Value-Added Pharmacist Services.

Value-added pharmacy services encompass traditional and emerging services provided by pharmacists to individual and entire populations of persons increasingly under the auspices of a public health mandate. The success of value-added pharmacy services is enhanced when they are carried out and assessed using appropriate theory-based paradigms. Many of the more important management theories for pharmacy services consider the servicescape of these services recognizing the uniqueness of each patient and service encounter that vary based upon health needs and myriad other factors. In addition, implementation science principles help ensure the financial viability and sustainability of these services. This commentary reviews some of the foundational management theories and provides a number of examples of these theories that have been applied successfully resulting in a greater prevalence and scope of value-added services being offered

LensPerfect: Gravitational Lens Massmap Reconstructions Yielding Exact Reproduction of All Multiple Images

We present a new approach to gravitational lens massmap reconstruction. Our massmap solutions perfectly reproduce the positions, fluxes, and shears of all multiple images. And each massmap accurately recovers the underlying mass distribution to a resolution limited by the number of multiple images detected. We demonstrate our technique given a mock galaxy cluster similar to Abell 1689 which gravitationally lenses 19 mock background galaxies to produce 93 multiple images. We also explore cases in which far fewer multiple images are observed, such as four multiple images of a single galaxy. Massmap solutions are never unique, and our method makes it possible to explore an extremely flexible range of physical (and unphysical) solutions, all of which perfectly reproduce the data given. Each reconfiguration of the source galaxies produces a new massmap solution. An optimization routine is provided to find those source positions (and redshifts, within uncertainties) which produce the "most physical" massmap solution, according to a new figure of merit developed here. Our method imposes no assumptions about the slope of the radial profile nor mass following light. But unlike "non-parametric" grid-based methods, the number of free parameters we solve for is only as many as the number of observable constraints (or slightly greater if fluxes are constrained). For each set of source positions and redshifts, massmap solutions are obtained "instantly" via direct matrix inversion by smoothly interpolating the deflection field using a recently developed mathematical technique. Our LensPerfect software is straightforward and easy to use and is made publicly available via our website.Comment: 17 pages, 18 figures, accepted by ApJ. Software and full-color version of paper available at http://www.its.caltech.edu/~coe/LensPerfect

The 78.4 day period of Cygnus XR-1

A search for a 78.4 day modulation in the high energy X-ray flux observed with OSO-8 and in the U-band optical polarization is reported. It is suggested that if such a modulation does exist, it is more likely to be related to the rotation of the free modes of oscillation of the primary than to the existence of a third body in the system