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In the current paper we consider an inverse boundary value problem of electromagnetism with nonlinear Second Harmonic Generation (SHG) process. We show the unique determination of the electromagnetic material parameters and the SHG susceptibility parameter of the medium by making electromagnetic measurements on the boundary. We are interested in the case when a frequency is fixed. [ABSTRACT FROM AUTHOR]

This paper presents an experimental study of the nonlinear dynamics of electrodynamic proof mass actuators. When inertial actuators are used in velocity feedback controllers, their nonlinear dynamics can affect the stability margin of the feedback loop. Thus, it is crucial to identify the nonlinearity sources and to build reliable models that can be implemented in the stability analysis. Firstly, the underlying linear model parameters of an inertial actuator are identified for small excitation signals. The inductance losses at high frequencies due to eddy currents have also been included in the electrical impedance model. Secondly, the nonlinear model of the inertial actuator is determined using the detection, characterisation and identification process. Finally, a numerical analysis is carried out to highlight the implications of nonlinear dynamics of inertial actuators. The proposed methodology is applied to several electromagnetic proof mass actuators, including when the proof mass is not accessible to be directly instrumented. [ABSTRACT FROM AUTHOR]

Personal exposimeters are currently used in studies assessing human exposure to electromagnetic fields. These devices are usually carried by an individual, but vehicles such as bicycle or car are also used. The aim of the present study was to propose a personal exposimeter attached to a drone to perform environmental radio-frequency measurements. Trials were carried out to determine whether: (i) the wireless communication between the remote controller and the drone affects the downlink mobile telephony bands by a cross-talk effect, and (ii) the structure of the drone alters the measurements of the exposimeter compared to when the meter is on a tripod. To apply this system to a real scenario, a 3D representation of the electric field in a building was obtained, and the attenuation due to the building of radiation from outside was estimated. Measurements of the electromagnetic field with this system will make it possible to monitor without risk the emissions of antennas in their close vicinity, and to validate propagation models experimentally. [Display omitted] • The wireless remote controller does not alter the bands of interest. • The structure of the drone affects the measurements in a quantifiable way. • Vertical electric field profile consistent with the antenna height and downtilt. • The attenuation of a building is estimated. [ABSTRACT FROM AUTHOR]

This study analyzes the well-known MUltiple SIgnal Classification (MUSIC) algorithm to identify unknown support of thin penetrable electromagnetic inhomogeneity from scattered field data collected within the so-called multi-static response matrix in limited-view inverse scattering problems. The mathematical theories of MUSIC are partially discovered, e.g., in the full-view problem, for an unknown target of dielectric contrast or a perfectly conducting crack with the Dirichlet boundary condition (Transverse Magnetic–TM polarization) and so on. Hence, we perform further research to analyze the MUSIC-type imaging functional and to certify some well-known but theoretically unexplained phenomena. For this purpose, we establish a relationship between the MUSIC imaging functional and an infinite series of Bessel functions of integer order of the first kind. This relationship is based on the rigorous asymptotic expansion formula in the existence of a thin inhomogeneity with a smooth supporting curve. Various results of numerical simulation are presented in order to support the identified structure of MUSIC. Although a priori information of the target is needed, we suggest a least condition of range of incident and observation directions to apply MUSIC in the limited-view problem. [ABSTRACT FROM AUTHOR]

We consider detecting objects on a flat ground by using the electromagnetic (EM) measurement made from a height. Our study is conducted in a very general and practical setting. The number of the target scatterers is not required to be known in advance, and each scatterer could be either an inhomogeneous medium or an impenetrable perfectly conducting (PEC) obstacle. Moreover, there might be multiscale components of small-size and extended-size (compared to the detecting wavelength) presented simultaneously. Some a priori information is required on scatterers of extended-size. The inverse problem is nonlinear and ill-conditioned. We propose a "direct" locating method by using a single EM far-field measurement. The results extend those obtained in [17,18] for locating multiscale EM scatterers located in a homogeneous space. [ABSTRACT FROM AUTHOR]

• The transfer function from disturbance to position deviation is obtained. • The influence of system parameters of the EMLA on servo dynamic stiffness is studied. • The servo dynamic stiffness experiment setup is built based on the linear motor. • Simulational and experimental results demonstrate the reliability of the analysis. The electromagnetic linear actuator has been widely used in new energy vehicles, aerospace, and intelligent robots in recent years. However, its application especially in high-precision servo control system is limited due to the disadvantage of insufficient dynamic stiffness. In this paper, a theoretical model of servo dynamic stiffness of electromagnetic linear actuator was established through analyzing the definition of servo dynamic stiffness. And the influence of system parameters of the electromagnetic linear actuator on servo dynamic stiffness was studied based on the frequency analysis of the Bode diagram and the mathematical simulation of MATLAB/Simulink. In addition, an innovative servo dynamic stiffness measurement method for electromagnetic linear actuators was established in this paper. The experimental and simulation results showed that the larger the coil resistance and the mover's mass, the smaller the servo dynamic stiffness and the worse the anti-disturbance ability of the system; the greater the coil inductance and force-current constant, the greater the servo dynamic stiffness, and the better the system's anti-disturbance ability. The experimental results were consistent with the theoretical analysis results. This study provides a reference for improving the dynamic characteristics of electromagnetic linear actuator and paves the way for its practical application in the high precision systems. [ABSTRACT FROM AUTHOR]

In this paper a denoising strategy based on the EEMD (Ensemble Empirical Mode Decomposition) is used to reduce the background noise in non-stationary signals, which represent the forces measured in scaled model testing of the emergency water landing of aircraft, generally referred to as ditching. Fuselage ditching tests are performed at a constant horizontal speed of 12 m/s with a controlled vertical motion, resulting in a vertical velocity at the beginning of the impact of 0.45 m/s. The measured data are affected by a large amplitude broadband noise, which has both a mechanical and an electronic origin. The noise sources cannot be easily avoided or removed, since they are associated with the vibrations of the structure of the towing carriage and with the interaction between the measurement chain and the electromagnetic fields. The EEMD noise reduction method is based on the decomposition of the signal into modes and on its partial reconstruction using the residue, the signal-dominant modes and some further modes treated with a thresholding technique, which helps to retain some of the sharp features of the signal. The strategy is developed and tested first on a synthetic signal with a superimposed and known background noise. The method is then verified on the measurement of the inertial force acting on the fuselage when it is moving in air, as in this case the added mass is negligible and the denoised force should equal the product of the mass and the acceleration, both of them being known. Finally, the procedure is applied to denoise the forces measured during the actual ditching experiment. The results are superior to those obtained from other classical filtering methods, such as a moving average filter and a low-pass FIR filter, particularly due to the enhanced capabilities of the EEMD-denoising strategy here developed to preserve the sharp features of the signals and to reduce the residual low-frequency oscillations of spurious origin. • Force measurements in water-entry tests are performed to study aircraft ditching. • The transient force measurements and the background noise are non-stationary signals. • EEMD is used to reduce the noise using a partial reconstruction with selected modes. • Interval thresholding is also employed to preserve the sharp variations in some modes. • The EEMD-based denoising provides superior results compared to classical filters. [ABSTRACT FROM AUTHOR]

Highlights: [•] Zonal average temperature and cloud parameters of Venus are N–S axial symmetric. [•] Zonal average temperature and cloud parameters are nearly stable with Julian date. [•] The dawn side below 75km is colder than the dusk side and vice versa above 75km. [•] Cloud top altitude decreases from 71km at low/mid-latitudes to 61km at the poles. [•] Cloud particle size increases from mid-latitudes towards the equator and the poles. [Copyright &y& Elsevier]

Abstract: The superconducting and lattice properties of δ-MoC0.681 were studied by electromagnetic measurements, synchrotron X-ray diffraction, neutron diffraction, and electron diffraction. The superconducting properties (T c=12K) of δ-MoC0.681 were well characterized by a weak coupling model. The carbon vacancies present in the host cubic structure were found to be robust, although the material was synthesized from stoichiometric carbon and Mo powder under a high-pressure of 6GPa. A thermodynamically-stable structure with ordered vacancies did not account for the robust features of δ-MoC0.681 since the vacancies are unlikely to be ordered in long range in the host structure. A model based on inherent phonon instability theoretically predicted for a stoichiometric MoC phase might be responsible for the robust features of δ-MoC0.681. [Copyright &y& Elsevier]

Abstract: The Cassini probe observed a young and smooth surface around the south pole of Enceladus, while around the north pole the surface was found to be relatively old and inactive (Porco, C.C. et al. [2006]. Science 311, 1393–1401). This heterogeneous surface implies that the ice thickness of Enceladus is not uniform between the north and south polar regions. Determining the thickness of the icy layer is important to confirm the existence of an internal ocean as well as to reveal the heating mechanism of Enceladus. We show that the measurement of radio waves induced by cosmic neutrinos can be an effective method to constrain the ice thickness of a localized area where conventional gravity or electromagnetic field measurements cannot be used. This method could be used to constrain the thickness of the icy layer on Enceladus even if the ice is a few tens of kilometers thick, measuring over a period of several years, which greatly exceeds the ability of radar sounding, and hence could be used in future orbiter missions. [Copyright &y& Elsevier]

• A multi-property evaluation method for a gas sample based on the sound speed and relative permittivity measurements was proposed. • Validity and reliability of the experimental apparatus using a cylindrical acoustic-electromagnetic resonator was proved by measurement results for Ar. • The ideal-gas specific heat capacity was derived from the sound speed data through the acoustic-virial equation. • The ideal-gas molar polarization, dipole moment, molecular polarizability, and density were derived from the relative permittivity data through the dielectric-virial equation. This study proposes a multi-property evaluation method for a gas sample on the basis of sound speed and relative permittivity measurements by using a cylindrical acoustic-electromagnetic resonator. Validity and reliability of the present apparatus were confirmed from the measurement result for Ar with the relative standard uncertainties of 2 × 10−4 for the sound speed and 4 × 10−6 for the relative permittivity. The sound speed and the relative permittivity measurements for trans -1-chloro-3,3,3-trifluoropropene, which is known as R1233zd(E), were carried out in the wide temperature and pressure ranges to demonstrate the multi-property evaluation for a polar molecular sample. Firstly, specific heat capacity and molar polarization in the ideal-gas state were derived from the sound speed and the relative permittivity data, respectively, based on the acoustic- and the dielectric-virial equations. Secondly, linear regression of the ideal-gas molar polarization and temperature data leaded information of dipole moment and molecular polarizability in accordance with Debye equation. The density-virial coefficients were deduced by use of an empirical correlation with the determined dipole moment on the basis of the corresponding states principle so that the acoustic- and the dielectric-virial coefficients were separately determined from polynomial regression analysis of the sound speed and the relative permittivity data, respectively. Finally, the relative permittivity data in combination with the determined dielectric-virial coefficients yield the value of density. The acquired multi-property data for R1233zd(E) were compared with the existing equation of state or reference model. [ABSTRACT FROM AUTHOR]

Abstract: We present a comprehensive examination of Jupiter''s “gossamer” rings based on images from Voyager, Galileo, the Hubble Space Telescope and the W.M. Keck Telescope. We compare our results to the simple dynamical model of Burns et al. [Burns, J.A., Showalter, M.R., Hamilton, D.P., Nicholson, P.D., de Pater, I., Ockert-Bell, M., Thomas, P., 1999. Science 284, 1146–1150] in which dust is ejected from Amalthea and Thebe and then evolves inward under Poynting–Robertson drag. The ring follows many predictions of the model rather well, including a linear reduction in thickness with decreasing radius. However, some deviations from the model are noted. For example, additional material appears to be concentrated just interior to the orbits of the two moons. At least in the case of Amalthea''s ring, that material is in the same orbital plane as Amalthea''s inclined orbit and may be trapped at the Lagrange points. Thebe''s ring shows much larger vertical excursions from the model, which may be related to perturbations by several strong Lorentz resonances. Photometry is consistent with the dust obeying a relatively flat power-law size distribution, very similar to dust in the main ring. However, the very low backscatter reflectivity of the ring, and the flat phase curve of the ring at low phase angles, require that the ring be composed of distinctly non-spherical particles. [Copyright &y& Elsevier]

Abstract: Shkuratov and Zubko [Shkuratov, Yu.G., Zubko, E., 2008. Icarus 194, 850–852] criticize our paper [Petrova, E.V., Tishkovets, V.P., Jockers, K., 2007. Icarus 188, 233–245]. With this comment we reply to this criticism. We show that the experimental data and the modeling calculations presented by these authors cannot disprove the near-field effect as an important contributor to the scattering mechanisms considered in our paper. [Copyright &y& Elsevier]

Abstract: A photometric analysis of the S-type Asteroid 25143 Itokawa is performed over multiple wavelengths ranging from 0.85 to 2.10 μm based on disk-resolved reflectance spectra obtained with the Hayabusa near-infrared spectrometer (NIRS). We derive the global photometric properties of Itokawa in terms of Hapke''s photometric model. We find that Itokawa has a single-scatter albedo that is 35–40% less than that of Asteroid 433 Eros. Itokawa also has a single-particle phase function that is more strongly back-scattering than that of Eros. Despite its hummocky surface strewn with large boulders, Itokawa exhibits an opposition effect. However, the total amplitude of the opposition surge for Itokawa was estimated to be less than unity while Eros and other S-type asteroids have been found to have model values exceeding unity. The wavelength dependence of the opposition surge width reveals that coherent backscatter contributes to the opposition effect on Itokawa''s surface. The photometric roughness of Itokawa is well constrained to a value of 26° ± 1° which is similar to Eros, suggesting that photometric roughness models the smallest surface roughness scale for which shadows exist. [Copyright &y& Elsevier]

Abstract: Photometric observations were conducted on eight Aten near-Earth asteroids, with the goal of building physical models for the objects (85989) 1999 , (86450) 2000 , (86667) 2000 , (137170) 1999 , 1999 MN, 2000 , 2002 JC and 2003 . The results show rotation periods from 2.3 to almost 26 h. Some objects exhibit amplitudes higher than one magnitude on their lightcurves (1999 , 2000 and 2003 ). Phase curve values (β, , see below) were derived for four Atens and values were found for two. Five Atens were classified by using their and color indices. This taxonomy was compared with the phase coefficient–albedo correlation defined by Belskaya and Shevchenko [Belskaya, I.N., Shevchenko, V.G., 2000. Icarus 147, 94–105]. Color variations during rotation and phase angle change were searched for. Our study demonstrates the high variety among Atens. Five out of the eight Atens are binaries or possible binaries, a significantly higher fraction than the expected 15% [Bottke, W.F., Melosh, H.J., 1996. Nature 281, 51–53]. The lightcurve of 2000 exhibits a binary character with a probable highly eccentric orbital rotation of the secondary component. The different periods of the known binary 1999 ''s are easily detected. Other Atens have lightcurve with features such as high amplitude, V-shaped minima and U-shaped maxima that can be interpreted as a binary asteroid with a synchronous rotation (2003 , 2000 and perhaps also 1999 ). The very red colors of 2000 suggest a unique surface composition for this near-Earth object. [Copyright &y& Elsevier]

Abstract: Six nights of BVR photometry and three nights of R photometry were collected over a month-long period shortly after the Cassini encounter with Hyperion on September 24 2005. Our observations were designed to help constrain the rotational state of the chaotically rotating satellite. Fourier analysis of our lightcurve data yields three possible periods: , , and . Our B–V and V–R colors agree well with previous ground-based and Voyager 2 measurements. [Copyright &y& Elsevier]

Abstract: Thermal lightcurves of Asteroid Vesta with significant amplitude have been observed at 870 μm (345 GHz) using the MPIfR 19-channel bolometer of the Heinrich–Hertz Submillimeter Telescope. Shape and albedo are not sufficient to explain the magnitude of this variation, which we relate to global variations in thermal inertia and/or other thermophysical parameters. Vesta''s lightcurve has been observed over several epochs with the same general shape. However, there are some changes in morphology that may in part be related to viewing geometry and/or asteroid season. Inconsistent night-to-night variations exhibit the inherent difficulties in photometry at this wavelength. We are able to match the observed brightness temperatures with a relatively simple thermal model that integrates beneath the surface and assumes reasonable values of thermal inertia, loss tangent and refractive index, and without having to assume low values of emissivity in the submillimeter. High flux portions of the submillimeter lightcurve are found to correspond to regions with weak mafic bands observed in Hubble Space Telescope images. [Copyright &y& Elsevier]

Abstract: On August 11, 2004, we made adaptive optics observations of the Uranus and Neptune systems with the Keck II Near Infrared Camera. Uranus and Triton were observed in three broadband filters (J, H, and K-prime) and four narrowband filters [Hcont, FeII, He1_B, and ]. Miranda, Ariel, Umbriel, and Oberon were observed in the four narrowband filters only. To achieve the highest possible photometric accuracy, and thus the tightest possible constraints on atmospheric aerosol models and gas mixing ratios, we used aperture photometry that accounted for the dependence of point-spread functions and growth curves on the adaptive optics reference object, and accounted for recently determined phase curves of each object. The satellite albedos we determined were compared with published relative spectra to verify the relative consistency of our observations, which were subsequently used to convert published relative spectra to absolute spectra. We used these absolute spectra and synthetic photometry methods to compare published values in dissimilar photometric systems to each other and to our observations. We find our satellite albedos in best agreement with photometry from Karkoschka [Karkoschka, E., 2001. Icarus 151, 51–68], which is the best characterized and most contemporaneous data set. Our estimated absolute accuracy of 5% to 8% is consistent with these intercomparisons. We obtained the following ring-subtracted and discrete feature-free albedos of Uranus: J: , H: , : , Hcont: , FeII: , He1_B: , and H2: . [Copyright &y& Elsevier]

Abstract: We present spectroscopic and photometric observations, spanning the optical UV to the far red, before, during, and after the NASA Deep Impact event of July 4, 2005. The inner 2000 km of the pre- and post-impact coma was about 0.3 magnitude redder in B–R than in the outer coma. The pre-impact spectrum was a faint reflected solar spectrum dominated by molecular emissions extending from the nucleus. The post-impact light curve in R and I showed a rapid rise consistent with an expanding optically thick cloud during the first 18 min after impact. During the next 8 min the cloud became optically thin. Sixty minutes after impact the impact R-band flux reached a plateau at , the comet brightening by a factor of ∼4.3 above its pre-impact value observed in a 15″ aperture. The mean expansion velocity of the grains during the first 49 min was . The spectrum became dominated by scattered sunlight during the first hour after impact. The volume scattering function (VSF) observed 32 min after impact shows strong reddening. At 49 min, however, the VSF shows an additional twofold increase in the blue but only a 20% increase at 5500 Å. Post-impact spectra and R–I photometry showed rapid reddening. The particle size distribution, dominated by 1–2.5 μm particles shortly after impact, changed dramatically during the first hour due to sublimation of water-ice particles of this size. On the night following impact the comet was still substantially brighter than before impact, but R–I had returned to its pre-impact value. B–R remained significantly redder. The ejecta 25 h after impact was fan-shaped subtending ∼180° roughly symmetrical about position angle 225°. The mean expansion velocity 90° from the direction to the Sun was . [Copyright &y& Elsevier]

Abstract: We report time-resolved imaging UV photometry of Comet 9P/Tempel 1 during the interval 2005 June 29–2005 July 21, including intensive coverage of the collision with the Deep Impact probe and its immediate aftermath. The nuclear flux of the comet begins to rise within minutes of the collision, and peaks about 3 h after impact. There is no evidence for a prompt flash at the time of impact. The comet exhibits a significant re-brightening about 40 h after the initial outburst, consistent with the rotation period of the comet, with evidence for further periodic re-brightenings on subsequent rotations. Modelling of the brightness profile of the coma as a function of time suggests two distinct velocity systems in the ejecta, at de-projected expansion speeds of 190 and 550 m/s, which we suggest are due to dust and gas, respectively. There is a distinct asymmetry in the slower-moving (dust) component as a function of position angle on the sky. This is confirmed by direct imaging analysis, which reveals an expanding plume of material concentrated in the impact hemisphere. The projected expansion velocity of the leading edge of this plume, measured directly from the imaging data, is 190 m/s, consistent with the velocity of the dust component determined from the photometric analysis. From our data we determine that a total of water molecules were ejected in the impact, together with a total scattering area of dust at 300 nm of . [Copyright &y& Elsevier]

Abstract: The photometric properties of the nucleus of Comet 9P/Tempel 1 are studied from the disk-resolved color images obtained by Deep Impact (DI). Comet Tempel 1 has typical photometric properties for comets and dark asteroids. The disk-integrated spectrum of the nucleus of Tempel 1 between 309 and 950 nm is linear without any features at the spectral resolution of the filtered images. At V-band, the red slope of the nucleus is per 100 nm at 63° phase angle, translating to , , and . No phase reddening is confirmed. The phase function of the nucleus of Tempel 1 is constructed from DI images and earlier ground-based observations found from the literature. The phase coefficient is determined to be between 4° and 117° phase angle. Hapke''s theoretical scattering model was used to model the photometric properties of this comet. Assuming a single Henyey–Greenstein function for the single-particle phase function, the asymmetry factor of Tempel 1 was fitted to be , and the corresponding single-scattering albedo (SSA) was modeled to be at 550 nm wavelength. The SSA spectrum shows a similar linear slope to that of the disk-integrated spectrum. The roughness parameter is found to be , and independent of wavelength. The Minnaert k parameter is modeled to be . The photometric variations on Tempel 1 are relatively small compared to other comets and asteroids, with a full width at half maximum of albedo variation histogram, and for color. Roughness variations are evident in one small area, with a roughness parameter about twice the average and appearing to correlate with the complex morphological texture seen in high-resolution images. [Copyright &y& Elsevier]

Abstract: Near-simultaneous R- and J-band photometric measurements of the short-period Comets 2P/Encke and the Deep Impact mission target 9P/Tempel 1 were obtained. The resulting colors are and for Encke and Tempel 1, respectively. Tempel 1''s color is redder than the solar color index of +0.76. The Tempel 1 observations directly detected the nucleus while the Encke observations likely suffered from coma contamination. [Copyright &y& Elsevier]

Abstract: On UT 2000 August 21 we obtained simultaneous visible and mid-infrared observations of Comet 9P/Tempel 1, the target of the upcoming NASA Discovery Program mission Deep Impact. The comet was still quite active while 2.55 AU from the Sun (post-perihelion). Two independent analyses of our data, one parameterizing the coma morphology and the other modeling infrared spectrophotometry, show that the nucleus''s cross section at the time the data were taken corresponds to an effective radius of . Based on visible-wavelength photometry of the comet taken during this observing run and others in the summer of 2000, all of which show the rotational modulation of the nucleus''s brightness, we find that the infrared data were obtained near the maximum of the light curve. If we assume that the nucleus''s light curve had a peak-to-valley range of , then the mean effective radius is . Visible-wavelength photometry of the nucleus, including data published by other groups, lets us constrain the nucleus''s R-band geometric albedo: . The nucleus''s flux contributed about 85% of the light in the mid-infrared images. [Copyright &y& Elsevier]

Abstract: We present results from CCD observations of Comet 2P/Encke acquired at Steward Observatory''s 2.3 m Bok Telescope on Kitt Peak. The observations were carried out in October 2002 when the comet was near aphelion. Rotational lightcurves in B-, V-, and R-filters were acquired over two nights of observations, and analysed to study the physical and color properties of the nucleus. The average apparent R-filter magnitude across both nights corresponds to a mean effective radius of , and this value is similar to that found for the V- and B-filters. Taking the observed brightness range, we obtain for the semi-axial ratio of Encke''s nucleus. Applying the axial ratio to the R-filter photometry gives nucleus semi-axes of , using the empirically-derived albedo and phase coefficient. No coma or tail was seen despite deep imaging of the comet, and flux limits from potential unresolved coma do not exceed a few percent of the total measured flux, for standard coma models. This is consistent with many other published data sets taken when the comet was near aphelion. Our data includes the first detailed time series multi-color measurements of a cometary nucleus, and significant color variations were seen on October 3, though not repeated on October 4. The average color indices across both nights are: and (). We analysed the R-filter time-series photometry using the method of Harris et al. [Harris, A.W., Young, J.W., Bowell, E., Martin, L.J., Millis, R.L., Poutanen, M., Scaltriti, F., Zappala, V., Schober, H.J., Debehogne, H., Zeigler, K.W., 1989. Icarus 77, 171–186] to constrain the rotation period of the comet''s nucleus, and find that a period of will satisfy the data, however the errors bars are large. We have successfully linked our data with the September 2002 data from Fernández et al. [Fernández, Y.R., Lowry, S.C., Weissman, P.R., Mueller, B.E.A., Samarasinha, N.H., Belton, M.J.S., Meech, K.J., 2005. Icarus 175, 194–214]—taken just 2–3 weeks before the current data set—and we show that a rotation period of just over 11 h works extremely well for the combined data set. The resulting best-fit period is , consistent with the Fernández et al. value. [Copyright &y& Elsevier]

Abstract: The results of the 9P/Tempel 1 CARA (Cometary Archive for Amateur Astronomers) observing campaign is presented. The main goal was to perform an extended survey of the comet as a support to the Deep Impact (DI) Mission. CCD R, I and narrowband aperture photometries were used to monitor the Afρ quantity. The observed behavior showed a peak of 310 cm 83 days before perihelion, but we argue that it can be distorted by the phase effect, too. The phase effect is roughly estimated around 0.0275 mag/degree, but we had no chance for direct determination because of the very similar geometry of the observed apparitions. The log-slope of Afρ was around −0.5 between about 180–100 days before the impact but evolved near the steady-state like 0 value by the impact time. The DI module impact caused about a 60% increase in the value of Afρ and a cloud feature in the coma profile which was observed just after the event. The expansion of the ejecta cloud was consistent with a fountain model with initial projected velocity of 0.2 km/s and . Referring to a 25,000 km radius area centered on the nucleus, the total cross section of the ejected dust was 0.06 days after the impact, and 1.93 days after the impact (A is the dust albedo). Five days after the event no signs of the impact were detected, nor deviations from the expected activity referring both to the average pre-impact behavior and to the previous apparitions. [Copyright &y& Elsevier]

Abstract: We report time-resolved imaging UV photometry of Comet 9P/Tempel 1 during the interval 2005 June 29–2005 July 21, including intensive coverage of the collision with the Deep Impact probe and its immediate aftermath. The nuclear flux of the comet begins to rise within minutes of the collision, and peaks about 3 h after impact. There is no evidence for a prompt flash at the time of impact. The comet exhibits a significant re-brightening about 40 h after the initial outburst, consistent with the rotation period of the comet, with evidence for further periodic re-brightenings on subsequent rotations. Modelling of the brightness profile of the coma as a function of time suggests two distinct velocity systems in the ejecta, at de-projected expansion speeds of 190 and 550 m/s, which we suggest are due to dust and gas, respectively. There is a distinct asymmetry in the slower-moving (dust) component as a function of position angle on the sky. This is confirmed by direct imaging analysis, which reveals an expanding plume of material concentrated in the impact hemisphere. The projected expansion velocity of the leading edge of this plume, measured directly from the imaging data, is 190 m/s, consistent with the velocity of the dust component determined from the photometric analysis. From our data we determine that a total of water molecules were ejected in the impact, together with a total scattering area of dust at 300 nm of . [Copyright &y& Elsevier]

Abstract: The photometric properties of the nucleus of Comet 9P/Tempel 1 are studied from the disk-resolved color images obtained by Deep Impact (DI). Comet Tempel 1 has typical photometric properties for comets and dark asteroids. The disk-integrated spectrum of the nucleus of Tempel 1 between 309 and 950 nm is linear without any features at the spectral resolution of the filtered images. At V-band, the red slope of the nucleus is per 100 nm at 63° phase angle, translating to , , and . No phase reddening is confirmed. The phase function of the nucleus of Tempel 1 is constructed from DI images and earlier ground-based observations found from the literature. The phase coefficient is determined to be between 4° and 117° phase angle. Hapke''s theoretical scattering model was used to model the photometric properties of this comet. Assuming a single Henyey–Greenstein function for the single-particle phase function, the asymmetry factor of Tempel 1 was fitted to be , and the corresponding single-scattering albedo (SSA) was modeled to be at 550 nm wavelength. The SSA spectrum shows a similar linear slope to that of the disk-integrated spectrum. The roughness parameter is found to be , and independent of wavelength. The Minnaert k parameter is modeled to be . The photometric variations on Tempel 1 are relatively small compared to other comets and asteroids, with a full width at half maximum of albedo variation histogram, and for color. Roughness variations are evident in one small area, with a roughness parameter about twice the average and appearing to correlate with the complex morphological texture seen in high-resolution images. [Copyright &y& Elsevier]

Abstract: The results of the multiaperture photometry of Comet Shoemaker–Levy 1991 T2 in the pre-perihelion and P/deVico in the post-perihelion period with the narrowband CN, C2 and Blue Continuum (BC) IHW filters are presented. A Haser model of the molecular coma was used for the determination of the parent and daughter scale-lengths and production rates of the radicals. The comets showed some substantial differences between their parent scale-lengths. The CN parent scale-length (at 1.0 AU) was for Comet Shoemaker–Levy and for P/deVico, the C2 parent scale-lengths were respectively and . Such divergences could be interpreted in the frame of different scenarios of emission of cometary parents, either from a nucleus or from a volume source. The daughter scale-lengths for these comets were quite similar, namely: and for CN and and for C2. We determined the Afρ parameter for apertures of different radii. A Monte Carlo model of the dust coma was used to obtain the dust ejection velocity. It was of the order of 0.1 km s−1 for both comets. The power index of the distribution of the β-parameter of dust particles (ratio of light pressure to the solar gravitation) was of the order of 3 for C/Shoemaker–Levy and close to 2 for P/deVico. The dependence on heliocentric distance () of the radical and dust production rates for P/deVico in the range of 0.7–1.0 AU was described by the power law function with a power index equal to: for CN, for C2 and for dust. Relative abundances of the dynamically new Comet Shoemaker–Levy and short-period P/deVico were quite similar with an enhancement of C2 comparing with standard values taken from A''Hearn et al. (1995). [Copyright &y& Elsevier]

Abstract: BVI photometry of Triton and Proteus was derived from HST images taken in 1997. The VEGAMAG photometric technique was used. Triton was found to be brighter by a few percent than observations of the 1970''s and 1980''s, as expected due to the increasingly greater exposure of the bright south polar region. The leading side was also found to be brighter than the trailing side by 0.09 mag in all filters—50% larger than reported by Franz [Franz, O.G., 1981. Icarus 45, 602–606]. Contrary to our previous results [Pascu, D., et al., 1998. Bull. Am. Astron. Soc. 30, 1101], we found no episodic reddening. Our previous conclusions were based on an inaccurate early version of the Charge Transfer Efficiency (CTE) correction. The present result limits the start of the reddening event reported by Hicks and Buratti [Hicks, M.D., Buratti, B.J., 2004. Icarus 171, 210–218]. Our (B–V) result of supports the global blueing described by Buratti et al. [Buratti, B.J., Goguen, J.D., Gibson, J., Mosher, J., 1994. Icarus 110, 303–314]. Our observations of July 1997 agree with the Voyager results and are among the bluest colors seen. We found Proteus somewhat brighter than earlier studies, but in good agreement with the recent value given by Karkoschka [Karkoschka, E., 2003. Icarus 162, 400–407]. A leading/trailing brightness asymmetry was detected for Proteus, with the leading side 0.1 mag brighter. The unique differences in action of the endogenic and exogenic processes on Triton and Proteus provides an opportunity to separate the endogenic and exogenic effects on Triton. [Copyright &y& Elsevier]

Abstract: The article presents results of CCD photometry in R-band of a dynamically new Comet C/2001 K5 (LINEAR), obtained at a heliocentric distance of about 5.6 AU, after the perihelion passage. Being so distant from the Sun, this comet was extremely active (Afρ close to 2000 cm), exhibiting quite well developed dust coma and tail. During the observations, general photometric behavior of the comet with heliocentric distance r was well described by the function with coefficient . The radial profiles of the coma were found to be undulated, with mean slope of the dependence between cometary magnitude and of aperture radius (at comet distance) equal to . The light curve of Comet LINEAR exhibited short-term variability which we attributed to cyclic changes of dust emission, induced by nucleus rotation. Model computations by some authors have revealed that active comets can change their spin status quite substantially even during a single orbital revolution. Thus, attempting to search for a rotation frequency, we have modified the classical PDM approach by including the spin acceleration term. Such DynamicalPDM (DPDM) method revealed the most reliable solution for the frequency and its first time-derivative (index “zero” denotes reference to the mid time of the whole observing run), indicating a rapid spin-down of the nucleus. These parameters are equivalent to the rotation period of and its relative increment of . We present the most probable evolution of the rotation frequency of Comet LINEAR, based on the results of periodicity analysis and a simple, almost parameter independent, dynamical model of nucleus rotation. It is also shown that the DPDM may be an effective tool for determination of a nucleus radius, which provided us with the value of for Comet LINEAR. [Copyright &y& Elsevier]

Abstract: Images of Mars in the visible to near-infrared acquired from 1996 to 2005 using the Hubble Space Telescope WFPC2 have been used to model the martian surface photometric function at 502, 673, 953, and 1042 nm. These data range in spatial resolution from 12 to 70 km/pixel at the sub-Earth point, and in phase angle coverage from 0.34° to 40.5°. The WFPC2 images have been calibrated to radiance factor or and projected to a cylindrical map for coregistration and comparison to similarly mapped spacecraft data sets of albedo, topography, thermal inertia, composition, and geology. We modeled the observed as a function of phase angle using Minnaert, Lambert, lunar–Lambert, and Hapke photometric functions for numerous regions of interest binned into albedo units defined by Viking and TES albedo maps, and thermal-inertia units defined by TES thermal-inertia maps. Visibly opaque water-ice clouds and data acquired under high dust opacity conditions were excluded from the analysis. Our modeling suggests that under average to low atmospheric dust opacity conditions and over this range of phase angles, the photometric properties of the martian surface at 502, 673, 953, and 1042 nm are best modeled by lunar–Lambert functions with parameters derived for three surface units defined by low, moderate, and high TES bolometric albedos. [Copyright &y& Elsevier]

Abstract: Recent dynamical analyses of the Kuiper belt have introduced a rigorous classification scheme, determined the mean orbital plane, and identified “Core” and “Halo” populations as a function of inclination with respect to this plane (Elliot, J.L., Kern, S.D., Clancy, K.B., Gulbis, A.A.S., Millis, R.L., Buie, M.W., Wasserman, L.H., Chiang, E.I., Jordan, A.B., Trilling, D.E., Meech, K.J., 2005. Astron. J. 129, 1117–1162). Here, we use new observations and existing data to investigate the colors of Kuiper belt objects (KBOs) within this framework. With respect to the bulk KBO color distribution (all objects for which we have and colors; median ), we find that the population of objects classified following (Elliot, J.L., Kern, S.D., Clancy, K.B., Gulbis, A.A.S., Millis, R.L., Buie, M.W., Wasserman, L.H., Chiang, E.I., Jordan, A.B., Trilling, D.E., Meech, K.J., 2005. Astron. J. 129, 1117–1162) as Classical tends to be red () while the Scattered Near population is mostly neutral (). Colors of Scattered Extended and Resonant objects are consistent with the bulk distribution. Separating objects into specific resonances demonstrates that the color of the Resonant sample is dominated by KBOs in the 3:2 resonance, which is consistent with previous findings. Unlike the objects in the 3:2 resonance, however, the majority of objects in the 5:2 resonance are neutral and all but one of the objects in the 4:3, 5:3, 7:4, 2:1, and 7:3 resonances are red. In particular, the objects in the 7:4 resonance are remarkably red. We find that the colors of KBOs in the Core (low-inclination) and Halo (high-inclination) are statistically different, with Core objects being primarily red and Halo objects having a slight tendency to be neutral. Notably, virtually all of the non-Resonant Core objects are red. This combination of low inclination, unperturbed orbits and red colors in the Core may be indicative of a relic grouping of objects. [Copyright &y& Elsevier]

Abstract: We present photometric and astrometric results from four epochs of ground-based observations at the Magellan telescopes of the Kuiper belt binary 2003QY90. Resolved observations show both components to be highly variable and often of nearly equal brightness, causing difficulty in distinguishing between the primary and secondary components for observations spaced widely in time. Resolved lightcurve observations on one night show one component to have a single-peaked rotation period of and a peak-to-peak amplitude of . The other component exhibits a less constrained lightcurve, with a single-peaked rotation period of and a peak-to-peak amplitude of . Under the assumption of equal albedos, the diameter ratio is in the Sloan filter. While we cannot determine an orbit from our four distinct epochs of observation (due to ambiguity in component identification), we place limits on the orbital period of the system of 300–600 days, we find a minimum semi-major axis of 13,092 km for a circular orbit and a system mass range of depending on the identification of components in our observations. [Copyright &y& Elsevier]

Abstract: We present a new catalog of absolute nuclear magnitudes of Jupiter family (JF) comets, which is an updated version of our previous catalog [Tancredi, G., Fernández, J.A., Rickman, H., Licandro, J., 2000. Astron. Astrophys. Suppl. Ser. 146, 73–90]. From the new catalog we find a linear cumulative luminosity function (CLF) of slope for JF comets with . By considering this CLF combined with the few measured geometric albedos with their respective uncertainties, and assuming a canonical albedo of for those comets with undetermined albedos, we derive a cumulative size distribution that follows a power-law of index . The slope is similar to that derived from some theoretical collisional models and from some populations of Solar System bodies like the trans-neptunian objects. We also discuss and compare our size distribution with those by other authors that have recently appeared in the literature. Some striking differences in the computed slopes are explained in terms of biases in the studied samples, the different weights given to the brightest members of the samples, and discrepancies in the values of a few absolute nuclear magnitudes. We also compute sizes and fractions of active surface area of JF comets from their estimated absolute nuclear magnitudes and their water production rates. With the outgassing model that we use, about 60% of the computed fractions f of active surface area are found to be smaller than 0.2, with one case (28P/Neujmin 1) of no more than 0.001, which suggests that JF comets may transit through stages of very low activity, or even dormancy. There is an indication that JF comets with radii have active fractions , which might be due to the rapid formation of insulating dust mantles on larger nuclei. [Copyright &y& Elsevier]

Abstract: Macular pigment may protect against age related macular degeneration (AMD), because of its capability to absorb blue light and scavenge free radicals. Since age is the major risk factor in AMD, a fundamental question to be answered is the possible age dependence of the macular pigment optical density (MPOD) in normal healthy subjects. In this study we used five methods to study a possible age effect: heterochromatic flickerphotometry, two setups for fundus reflectance spectroscopy, a Scanning Laser Ophthalmoscope (SLO) for obtaining reflectance, and the same SLO for autofluorescence maps. MPOD was determined from the reflected light by a full spectral analysis. We also used a new, directional analysis of the reflected light to estimate MPOD. The latter avoids the disturbing influence of stray-light. Digital subtraction at two wavelengths of log reflectance and digital subtraction of log autofluorescence obtained with the SLO provided MPOD maps. Together, all methods of measuring and of analysis provided seven MPOD estimates per subject. A total of 53 subjects, aged 19–76 years, completed all five measurements (and thus seven analyses). An additional 81 subjects, aged 18–70 years, were measured with one setup for fundus reflectance spectroscopy (and thus only two analyses). We could not find any association with age with all the objective techniques. Only MPOD values obtained with heterochromatic flickerphotometry showed a small, but significant decrease with age. This decrease was caused by an increase in the parafoveal data, suggesting that the central MPOD is unchanged with age. The bivariate correlation coefficients between all methods were significant (all p<0.001). [Copyright &y& Elsevier]

Abstract: Observations of stellar occultation by asteroids provide opportunities to directly measure dimensions and study physical parameters of asteroids. Existing asteroid occultation timing methods either record the occultation time directly or compute the occultation time from the measurement of length. In this work, we present a timing method to derive the occultation time from the measurement of magnitude, termed Integration Photometric Timing (IPT), which simply utilizes CCD photometry with relatively long exposures. Applications to two events, (3) Juno''s and (980) Anacostia''s, are given to demonstrate the use and feasibility of the IPT. The proposed method has the capability of timing asteroid occultations of faint stars because of its long exposure time. Thus, more observable events are expected, with professional large telescopes to be involved in asteroid occultation observations, especially for the case of Kuiper belt objects (KBOs) and other distant asteroids occultation. [Copyright &y& Elsevier]

Abstract: We present photometric observations of Centaur (60558) 2000 EC98 and trans-neptunian object (55637) 2002 UX25 at different phase angles and with different filters (mainly R but also V and B for some data). Results for 2000 EC98 are: (i) a rotation period of if a double-peaked lightcurve is assumed, (ii) a lightcurve amplitude of for the R band, (iii) a phase curve with and (R filter) and and (V filter) or a slope of (R filter) and (V filter), (iv) the color indices and (for ) and (for ). The rotation period is amongst the longest ever measured for Centaurs and TNOs. We also show that our photometry was not contaminated by any cometary activity down to magnitude . For 2002 UX25 the results are: (i) a rotation period of or (if a double-peaked lightcurve is assumed) (ii) a lightcurve amplitude of for the R band (and the 16.782 h period), (iii) a phase curve with and or a slope of (R filter), (iv) the color indices and . The phase curve reveals also a possible very narrow and bright opposition surge. Because such a narrow surge appears only for one point it needs to be confirmed. [Copyright &y& Elsevier]

Abstract: We present optical photometry of the Centaur 5145 Pholus during 2003 May and 2004 April using the facility CCD camera on the 1.8-m Vatican Advanced Technology Telescope on Mt. Graham, Arizona. We derive a double-peaked lightcurve and a rotation period of for Pholus, consistent with periods of and by Buie and Bus (1992, Icarus 100, 288–294) and Farnham (2001, Icarus 152, 238–245). We find a lightcurve peak-to-peak amplitude of 0.60 mag, significantly larger than peak-to-peak amplitude determinations of 0.15 and 0.39 mag by Buie and Bus and Farnham. We use the three observed amplitudes and an amplitude-aspect model to derive four possible rotational pole positions as well as axial ratios of and . If we assume an albedo of 0.04, we find Pholus has dimensions of . If we assume Pholus is a strengthless rubble-pile and its non-spherical shape is due to rotational distortion, our axial ratios and period measurements indicate Pholus has a density of 0.5 g cm−3, suggestive of an ice-rich, porous interior. By combining B-band and R-band lightcurves, we find and any color variation over the surface of Pholus must be smaller than 0.06 mag (i.e., much smaller than the range seen among the Centaur and Kuiper belt object populations). By combining our measurements with values in the literature, we find no evidence for any color variegation between the northern and southern hemispheres of Pholus. Observations of the Kuiper belt object 2004 DW (90482) over a time interval of seven hours show no color variation Our observations add to the growing body of evidence that individual Centaurs and KBOs exhibit homogeneous surface colors and hence gray impact craters on radiation reddened crusts are probably not responsible for the surprising range of colors seen among the Centaur and Kuiper belt object populations. [Copyright &y& Elsevier]

Abstract: We present new, near-aphelion, time series of photometry of Comet 2P/Encke in Cousins-R band. With these light curves we find that the dominant, synodic rotational periodicity is either or . This is in contrast to data from the 1980s published by others that are consistent with 15.08- and 22.6-h periods. Those periods do not satisfy our phased light curves, and also the 1980s data are not easily reconciled with our periods. This could be due to P/Encke having non-principal axis rotation or due to a drift in the rotation period caused by outgassing torques. We observed the comet at five epochs: July, August, September, and October 2001, and September 2002, and the comet was at times intrinsically brighter than expected for a bare nucleus, due to an apparent contribution from an unresolved coma. Three-quarters of the data were obtained in the second and fifth epochs, and we analyzed these two time series using both the phase-dispersion minimization and “WindowCLEAN” techniques. At both epochs and with both techniques strong periodicities were found near frequencies and . By then using visual inspection of the phased light curves to corroborate these frequencies, and by using the data from the other three epochs to properly align light curve features, we were able to derive and as the only solutions that satisfy all our observations. The periodicity due to is clearly seen in our data, but we cannot tell from our data alone whether it is a manifestation of the nucleus''s shape, non-principal axis rotation, or both. [Copyright &y& Elsevier]

Abstract: We present analyses and results from both narrowband photometry and CCD imaging of Comet 81P/Wild 2 from multiple apparitions, obtained in support of the Stardust mission. These data include photometric measurements from 12 days before the encounter and imaging from 3 days after. Using narrowband photometry from the different apparitions, we analyzed the dust and gas production rates as a function of heliocentric distance, finding a substantial seasonal effect where the production of OH, NH, and dust peaks 11–12 weeks before perihelion. The CN, C2, and C3 production show no such asymmetry, suggesting that there may be heterogeneities among different sources on the nucleus. The water production peaked at a level of approximately in 1997. A comparison of the relative abundances of minor gas species places Wild 2 in the “depleted” category in the A''Hearn et al. (1995, Icarus 118, 223) taxonomic classifications. Continuum measurements at multiple wavelengths indicate that the comet has a low dust-to-gas ratio, with moderately reddened dust. In our images we see a dust tail, an anti-tail and two well-defined jets. The primary jet, which persists for several months and is roughly aligned with the spin axis, has a source latitude , while the secondary jet is located on the opposite hemisphere between and . We used the apparent position angle of the primary jet to determine the pole orientation, , , and surmise that the nucleus is likely in a state of simple rotation. The primary source is continuously illuminated when Wild 2 is inbound and turns away from the Sun at about the time that the comet reaches perihelion, explaining the seasonal effects in the production rates. We measured lightcurves on several observing runs but saw no significant modulation, so no constraints can be set on the rotation rate. Images at different wavelengths show that the jets have the same colors as the dust in other regions in the coma and tail, indicating that the grain properties are similar throughout the coma. Radial profiles of the coma were measured in various directions on a number of different observing runs, and we discuss the findings from these measurements. Finally, we compare our results with other published data and attempt to predict future times at which observations should be obtained to help constrain additional properties. [Copyright &y& Elsevier]

A Moreland anomaloscope was modified to measure macular pigment optical density (MPOD) profiles by motion photometry. A grating (spatial frequency 0.38cdeg−1), whose alternate bars were filled, respectively, with 460nm (maximum MP absorption) and 580nm (zero MP absorption) lights, drifted steadily at 37°s−1. The subject adjusted the 580nm radiance to minimise perceived motion (equiluminance between 460 and 580nm). Five or more settings were made for two foveal fields (0.9° and 2.2° diameter) and 11 extrafoveal annular fields (0.8°–7.5° eccentricity). Twenty subjects made measurements for both eyes: some with replications. MPOD profiles varied in scale (0.18–0.75 for the 0.9° foveal field) and in shape. A mean profile was derived. Foveal data were optimally aligned with annular data in that profile when plotted at 0.71 of the foveal field radius. Factors that limit precision were identified, such as fixation errors foveally and Troxler’s effect parafoveally. [Copyright &y& Elsevier]

Measurement of the macular pigment optical density (MPOD) by heterochromatic flicker photometry (HFP) is accomplished by viewing a small circular stimulus that alternates between a test wavelength that is absorbed by the MP (typically— blue, 460 nm) and a reference wavelength that is not absorbed (typically—green, 540 nm). Flicker observed by the subject is reduced to a null point by adjusting the intensity of the former while viewing the stimulus centrally, and then peripherally. A higher intensity, I, of the blue component of the stimulus is needed under central viewing conditions owing to attenuation by the MP. The MPOD at the test wavelength is given by log (Icentral/Iperipheral). Variation of the test wavelength has been used to measure the MPOD spectrum. This in vitro MPOD spectrum matches that of the carotenoids present in the macular region of the retina and demonstrates the validity and specificity of this methodology. The distribution of MPOD in the retina can be determined with HFP using a series of annular stimuli of different diameters. [Copyright &y& Elsevier]

We present the characteristics of the dust comae of two comets, 126P/IRAS, a member of the Halley family (a near-isotropic comet), and 2P/Encke, an ecliptic comet. We have primarily used mid- and far-infrared data obtained by the ISOPHOT instrument aboard the Infrared Space Observatory (ISO) in 1996 and 1997, and mid-infrared data obtained by the SPIRIT III instrument aboard the Midcourse Space Experiment (MSX) in 1996. We find that the dust grains emitted by the two comets have markedly different thermal and physical properties. P/IRAS''s dust grain size distribution appears to be similar to that of fellow family member 1P/Halley, with grains smaller than 5 microns dominating by surface area, whereas P/Encke emits a much higher fraction of big (20 μm and higher) grains, with the grain mass distribution being similar to that which is inferred for the interplanetary dust population. P/Encke''s dearth of micron-scale grains accounts for its visible-wavelength classification as a “gassy” comet. These conclusions are based on analyses of both imaging and spectrophotometry of the two comets; this combination provides a powerful way to constrain cometary dust properties. Specifically, P/IRAS was observed preperihelion while 1.71 AU from the Sun, and seen to have a 15-arcmin long mid-infrared dust tail pointing in the antisolar direction. No sunward spike was seen despite the vantage point being nearly in the comet''s orbital plane. The tail''s total mass at the time was about 8×109 kg. The spectral energy distribution (SED) is best fit by a modified greybody with temperature T=265±15 K and emissivity #x03B5; proportional to a steep power law in wavelength λ: #x03B5;∝λ-α, where α=0.50±0.20 (2σ). This temperature is elevated with respect to the expected equilibrium temperature for this heliocentric distance. The dust mass loss rate was between 150–600 kg/s (95% confidence), the dust-to-gas mass loss ratio was about 3.3, and the albedo of the dust was 0.15±0.03. Carbonaceous material is depleted in the comet''s dust by a factor of 2–3, paralleling the C2 depletion in P/IRAS''s gas coma. P/Encke, on the other hand, observed while 1.17 AU from the Sun, had an SED that is best fit by a Planck function with T=270±15 K and no emissivity falloff. The dust mass loss rate was 70–280 kg/s (95% confidence), the dust-to-gas mass loss ratio was about 2.3, and the albedo of the dust was about 0.06±0.02. These conclusions are consistent with the strongly curved dust tail and bright dust trail seen by Reach et al. (2000; Icarus 148, 80) in their ISO 12-μm imaging of P/Encke. The observed differences in the P/IRAS and P/Encke dust are most likely due to the less evolved and insolated state of the P/IRAS nuclear surface. If the dust emission behavior of P/Encke is typical of other ecliptic comets, then comets are the major supplier of the interplanetary dust cloud. [Copyright &y& Elsevier]

The outer Solar System object (29981) 1999 TD10 was observed simultaneously in the R, and J and H bands in September 2001, and in B, V, R, and I in October 2002. We derive , , , , and . Combining our data with the data from Rousselot et al. (2003, Astron. Astrophys. 407, 1139) we derive a synodic period of in agreement with the period from Rousselot et al. Our observations at the same time, with better S/N and seeing, show no evidence of a coma, contrary to the claim by Choi et al. (2003, Icarus 165, 101). [Copyright &y& Elsevier]

Interpretations of visible/near-infrared reflectance spectra of Mars are often complicated by the effects of dust coatings that obscure the underlying materials of interest. The ability to separate the spectral reflectance signatures of coatings and substrates requires an understanding of how their individual and combined reflectance properties vary with phase angle. Toward this end, laboratory multispectral observations of rocks coated with different amounts of Mars analog dust were acquired under variable illumination and viewing geometries using the Bloomsburg University Goniometer (BUG). These bidirectional reflectance distribution function (BRDF) data were fit with a two-layer radiative transfer model, which replicated BUG observations of dust-coated basaltic andesite substrates relatively well. Derived single scattering albedo and phase function parameters for the dust were useful in testing the model''s ability to derive the spectrum of a “blind” substrate (unknown to the modeler) coated with dust. Subsequent tests were run using subsets of the BUG data restricted by goniometric or coating thickness coverage. Using the entire data set provided the best constraints on model parameters, although some reductions in goniometric coverage could be tolerated without substantial degradation. Predictably, the most thinly coated samples provided the best information on the substrate, whereas the thickest coatings best replicated the dust. Dust zenith optical thickness values ∼0.6–0.8 best constrain the substrate and coating simultaneously, particularly for large ranges of incidence or emission angles. The lack of sufficient angles can be offset by having a greater number and range of coatings thicknesses. Given few angles and thicknesses, few constraints can be placed concurrently on the spectral properties of the coating and substrate. [Copyright &y& Elsevier]

Exposure of the general population to electromagnetic radiation emitted by mobile phone base stations is one of the greater concerns of residents affected by the proximity of these structures due to the possible relationship between radiated levels and health indicators. This study aimed to find a possible relationship between some health indicators and electromagnetic radiation measurements. A total of 268 surveys, own design, were completed by residents of a Madrid neighborhood surrounded by nine telephone antennas, and 105 measurements of electromagnetic radiation were taken with a spectrum analyzer and an isotropic antenna, in situ and in real – time, both outside and inside the houses. It was shown statistically significant p - values in headaches presence (p = 0.010), nightmares (p = 0.001), headache intensity (p < 0.001), dizziness frequency (p = 0.011), instability episodes frequency (p = 0.026), number of hours that one person sleeps per day (p < 0.001) and three of nine parameters studied from tiredness. Concerning cancer, there are 5.6% of cancer cases in the study population, a percentage 10 times higher than that of the total Spanish population. Discussion : People who are exposed to higher radiation values present more severe headaches, dizziness and nightmares. Moreover, they sleep fewer hours. • People who are exposed to higher radiation values present more severe headaches, dizziness and nightmares. • The methodology for obtaining electromagnetic radiation measurements should be reviewed. • The population continues to receive radiation peaks in distances greater than 200 m, no one is free from exposure. [ABSTRACT FROM AUTHOR]

In response to the demand from a growing number of people concerned about the possible impact of RF-EMF on health, the French National Frequency Agency (ANFR) has published a standardized protocol for in-situ measurements of radiofrequency electromagnetic fields (RF-EMF). This protocol was based on the search for the point of highest field strength and the use of spot measurement. In the framework of an epidemiological study, such spot measurements were implemented in the homes of 354 participants located in urban areas within 250 m of a mobile-phone base station (MPBS) and in the main beam direction of the antenna. Among the participants, more than half accepted to be enrolled in a longer-term study, among whom 152 were equipped with a personal exposure meter (PEM) for 48 h and 40 for seven continuous days. Both spot and PEM measurements quantified downlink field strengths, i.e. FM, TV3-4-5, TETRA I-II-III, 2 GHz–5GHz Wi-Fi, WiMax, GSM900, GSM1800, UMTS900, UMTS 2100, LTE800, LTE1800, and LTE2600. Spot measurements showed a mean/median field strength of 0.58/0.44 V/m for total RF-EMF and 0.43/0.27 V/m from the MPBS. RF-EMF from the MPBS was the dominant source of exposure in 64% of households. Exposure to RF-EMF was influenced by the position of the windows with respect to the MPBS, in particular line-of-site visibility, the distance of the antenna and the floor of the apartment. The PEM surveys showed the measured exposure to be higher during outings than at home and during the day than at night, but there was no difference between the weekends and working days. There was a strong correlation between exposure quantified by both spot and PEM measurements, although spot measures were approximately three times higher than those by PEMs. This study is the first to assess exposure to RF-EMF of people living near a MPBS in urban areas in France. These preliminary results suggest the value of using spot measurements to estimate the impact of the evolution of the mobile-phone network and technology on the exposure of populations to RF-EMF. The low levels of RF-RMF expressed as mean values do not necessarily rule out possible health effects of this exposure. • Mobile-phone base stations antennas are the dominant source of exposure to electromagnetic fields in surrounding housing. • Indoor exposure was influenced by the position of the windows with respect to the antenna and the floor of the building. • Personal electric field measurements showed higher values during trips than at home. • Personal electric field measurements were higher during the day but not different between working days and weekends. • Exposure quantified by spot and personal measurements was strongly correlated. [ABSTRACT FROM AUTHOR]

Multichannel Transcranial Magnetic Stimulation (mTMS) arrays enable multiple sites to be stimulated simultaneously or sequentially under electronic control without moving the system's stimulation coils. Here, we build and characterize the performance of a novel modular 3-axis TMS coil that can be utilized as a unit element in large-scale multichannel TMS arrays. We determined the basic physical characteristics of the 3-axis TMS coil x -, y - and z -elements using a custom 2-channel programmable stimulator prototype. We mapped the temporal rate-of-change of the induced magnetic field (dB/dt) on a 2D plane parallel to the coil surface (including an extended line for full spatial coverage) and compared those values with predictions from magnetic field simulations. Temperature measurements were carried out to assess the incorporated air-cooling method. We measured the mutual and self-inductances of the x/y/z -elements to assess coupling between them. Additionally, we measured and calculated the coupling between z -elements in the array configuration. Finally, we performed electric field simulations to evaluate the stimulation intensity and focality of the coil and compared the results to conventional TMS coils as well as demonstrated suitability of the 3-axis coil for a multichannel array configuration. The experimentally obtained dB/dt values validated the computational model of the 3-axis coil and therefore confirmed that both the coil and stimulator system are operating as intended. The air-cooling system was effective for brief high-frequency pulse trains and extended single- and paired-pulse TMS protocols. The electromagnetic simulations suggested that an array of the 3-axis coils would have comparable stimulation intensity to conventional TMS coils, therefore enabling clearly suprathreshold stimulation of the human brain. The recorded coil coupling between the x/y/z -elements was < 1% and the maximal coupling between z -elements in the array configuration was 1.8% and 3.4% for the measured and calculated values, respectively. We presented a 3-axis coil intended for multichannel TMS arrays. The electromagnetic measurements and simulations verified that the coil fabrication met the desired specifications and that the inductive coupling between the elements was negligible. The air-cooled 3-axis TMS coil appears suitable to be used as an element in multichannel TMS arrays. [ABSTRACT FROM AUTHOR]

Abstract: The combination of electromagnetic (EM) navigation with intraoperative fluoroscopic images has the potential to create the ideal environment for spinal surgical applications. This technology enhances standard intraoperative fluoroscopic information for localization of the pedicle entry point and trajectory and may be an effective alternative to other image-guided surgery (IGS) systems. This study was performed to assess the accuracy and time efficiency (placement and fluoroscopy) using EM navigation versus conventional fluoroscopy in the placement of pedicle guide-wires. Kirschner wire (K-wire) placement was performed in cadavers from T8 to S1 using EM navigation versus conventional fluoroscopy. Time for set-up, placement, and fluoroscopy was recorded. After insertion, the accuracy for each level was assessed for the presence and location of facet joint, pedicle, or vertebral cortical perforation using computed tomography imaging with multiplanar reconstructions. K-wire placements were 100% successful for both methods. Comparing EM-based IGS-assisted placement with the conventional fluoroscopy method showed a longer set-up time of 9.6 min versus 3.6 min, respectively. However, mean placement times of 6.3 min versus 9.7 min (P =0.005) and mean fluoroscopy times of 11 s versus 48 s (P <0.0001) were both shorter for the EM group. There were no significant differences in the proportion of pedicle, vertebral body, or facet joint breaches. A higher proportion of ideal trajectories was achieved in the EM group. Therefore, we have shown that an EM IGS system can assist the spine surgeon in minimally invasive pedicle screw insertion by providing high-accuracy K-wire placement with a significant reduction in fluoroscopy time. [Copyright &y& Elsevier]