Interpreting motion and force for narrow-band intermodulation atomic force microscopy

Intermodulation atomic force microscopy (ImAFM) is a mode of dynamic atomic force microscopy that probes the nonlinear tip-surface force by measurement of the mixing of multiple tones in a frequency comb. A high $Q$ cantilever resonance and a suitable drive comb will result in tip motion described by a narrow-band frequency comb. We show by a separation of time scales, that such motion is equivalent to rapid oscillations at the cantilever resonance with a slow amplitude and phase or frequency modulation. With this time domain perspective we analyze single oscillation cycles in ImAFM to extract the Fourier components of the tip-surface force that are in-phase with tip motion ($F_I$) and quadrature to the motion ($F_Q$). Traditionally, these force components have been considered as a function of the static probe height only. Here we show that $F_I$ and $F_Q$ actually depend on both static probe height and oscillation amplitude. We demonstrate on simulated data how to reconstruct the amplitude dependence of $F_I$ and $F_Q$ from a single ImAFM measurement. Furthermore, we introduce ImAFM approach measurements with which we reconstruct the full amplitude and probe height dependence of the force components $F_I$ and $F_Q$, providing deeper insight into the tip-surface interaction. We demonstrate the capabilities of ImAFM approach measurements on a polystyrene polymer surface.Comment: 12 pages, 7 figure

Clustering of Lyman alpha emitters at z ~ 4.5

We present the clustering properties of 151 Lyman alpha emitting galaxies at z ~ 4.5 selected from the Large Area Lyman Alpha (LALA) survey. Our catalog covers an area of 36' x 36' observed with five narrowband filters. We assume that the angular correlation function w(theta) is well represented by a power law A_w = Theta^(-beta) with slope beta = 0.8, and we find A_w = 6.73 +/- 1.80. We then calculate the correlation length r_0 of the real-space two-point correlation function xi(r) = (r/r_0)^(-1.8) from A_w through the Limber transformation, assuming a flat, Lambda-dominated universe. Neglecting contamination, we find r_0 = 3.20 +/- 0.42 Mpc/h. Taking into account a possible 28% contamination by randomly distributed sources, we find r_0 = 4.61 +/- 0.6 Mpc/h. We compare these results with the expectations for the clustering of dark matter halos at this redshift in a Cold Dark Matter model, and find that the measured clustering strength can be reproduced if these objects reside in halos with a minimum mass of 1-2 times 10^11 Solar masses/h. Our estimated correlation length implies a bias of b ~ 3.7, similar to that of Lyman-break galaxies (LBG) at z ~ 3.8-4.9. However, Lyman alpha emitters are a factor of ~ 2-16 rarer than LBGs with a similar bias value and implied host halo mass. Therefore, one plausible scenario seems to be that Lyman alpha emitters occupy host halos of roughly the same mass as LBGs, but shine with a relatively low duty cycle of 6-50%.Comment: 23 pages in preprint format, 4 figures, ApJ accepte

Discovery of a new supernova remnant G150.3+4.5

Large-scale radio continuum surveys have good potential for discovering new Galactic supernova remnants (SNRs). Surveys of the Galactic plane are often limited in the Galactic latitude of |b| ~ 5 degree. SNRs at high latitudes, such as the Cygnus Loop or CTA~1, cannot be detected by surveys in such limited latitudes. Using the available Urumqi 6 cm Galactic plane survey data, together with the maps from the extended ongoing 6 cm medium latitude survey, we wish to discover new SNRs in a large sky area. We searched for shell-like structures and calculated radio spectra using the Urumqi 6 cm, Effelsberg 11 cm, and 21 cm survey data. Radio polarized emission and evidence in other wavelengths are also examined for the characteristics of SNRs. We discover an enclosed oval-shaped object G150.3+4.5 in the 6 cm survey map. It is about 2.5 degree wide and 3 degree high. Parts of the shell structures can be identified well in the 11 cm, 21 cm, and 73.5 cm observations. The Effelsberg 21 cm total intensity image resembles most of the structures of G150.3+4.5 seen at 6 cm, but the loop is not closed in the northwest. High resolution images at 21 cm and 73.5 cm from the Canadian Galactic Plane Survey confirm the extended emission from the eastern and western shells of G150.3+4.5. We calculated the radio continuum spectral indices of the eastern and western shells, which are $\beta \sim -2.4$ and $\beta \sim -2.7$ between 6 cm and 21 cm, respectively. The shell-like structures and their non-thermal nature strongly suggest that G150.3+4.5 is a shell-type SNR. For other objects in the field of view, G151.4+3.0 and G151.2+2.6, we confirm that the shell-like structure G151.4+3.0 very likely has a SNR origin, while the circular-shaped G151.2+2.6 is an HII region with a flat radio spectrum, associated with optical filamentary structure, H$\alpha$, and infrared emission.Comment: 5 pages, 3 figures, accepted for publication of Astronomy and Astrophysic

The 4.5 +/- 0.5 Soft Gamma Repeaters in Review

Four Soft Gamma Repeaters (SGRs) have now been identified with certainty, and a fifth has possibly been detected. I will review their X-ray and gamma-ray properties in both outburst and quiescence. The magnetar model accounts fairly well for the observations of SGR1806-20 and SGR1900+14, but data are still lacking for SGR1627-41 and SGR0525-66. The locations of the SGRs with respect to their supernova remnants suggest that they are high velocity objects.Comment: This review article will appear in various forms in the following proceedings: 1. X-Ray Astronomy 1999 - Stellar Endpoints, AGN and the X-Ray Background (Astrophysical Letters and Communications, 2000) 2. Proceedings of the 5th Compton Symposium (AIP Press, 2000) 3. Proceedings of the 5th Huntsville GRB Symposium (AIP Press, April 2000

Between province and metropolis. The opera repertoire of the Pressburger Stadttheater in the late nineteenth century

The establishment and development of the Municipal Theater in Pressburg in the period 1886–1920 was closely linked with the cultural and social development of the city in the period following the Austrian-Hungarian Compromise in 1867. The theater was built by the rising stratum of Pressburg townsmen, based on a requirement of the Hungarian government. The theater was in the possession of the town that rented it to theater directors and their German and Hungarian companies. The theater had a primacy among provincial theaters in Hungary. This was mainly due to the vicinity of Vienna and the efforts to resemble the metropolis, notably by the local patriotism of Pressburg inhabitants who wanted their locality to be regarded as a leading Hungarian town. The opera performances and their reception in the newspapers demonstrate the history of culture of the town, mentalities and collective identifications of its citizens, and last but not least the history of culture of Central Europe

CHORUS Deliverable 4.5: Report of the 3rd CHORUS Conference

The third and last CHORUS conference on Multimedia Search Engines took place from the 26th to the 27th of May 2009 in Brussels, Belgium. About 100 participants from 15 European countries, the US, Japan and Australia learned about the latest developments in the domain. An exhibition of 13 stands presented 16 research projects currently ongoing around the world

Ultracool Field Brown Dwarf Candidates Selected at 4.5 microns

We have identified a sample of cool field brown dwarf candidates using IRAC data from the Spitzer Deep, Wide-Field Survey (SDWFS). The candidates were selected from 400,000 SDWFS sources with [4.5] <= 18.5 mag and required to have [3.6]-[4.5] >= 1.5 and [4.5] - [8.0] <= 2.0 on the Vega system. The first color requirement selects objects redder than all but a handful of presently known brown dwarfs with spectral classes later than T7, while the second eliminates 14 probable reddened AGN. Optical detection of 4 of the remaining 18 sources implies they are likely also AGN, leaving 14 brown dwarf candidates. For two of the brightest candidates (SDWFS J143524.44+335334.6 and SDWFS J143222.82+323746.5), the spectral energy distributions including near-infrared detections suggest a spectral class of ~ T8. The proper motion is < 0.25 "/yr, consistent with expectations for a luminosity inferred distance of >70 pc. The reddest brown dwarf candidate (SDWFS J143356.62+351849.2) has [3.6] - [4.5]=2.24 and H - [4.5] > 5.7, redder than any published brown dwarf in these colors, and may be the first example of the elusive Y-dwarf spectral class. Models from Burrows et al. (2003) predict larger numbers of cool brown dwarfs should be found for a Chabrier (2003) mass function. Suppressing the model [4.5] flux by a factor of two, as indicated by previous work, brings the Burrows models and observations into reasonable agreement. The recently launched Wide-field Infrared Survey Explorer (WISE) will probe a volume ~40x larger and should find hundreds of brown dwarfs cooler than T7.Comment: 13 pages, 6 figures, accepted for publication in the June 2010 issue of The Astronomical Journa

Spectroscopic Properties of the z=4.5 Lyman-alpha Emitters

We present Keck/LRIS optical spectra of 17 Lya-emitting galaxies and one Lyman break galaxy at z=4.5 discovered in the Large Area Lyman Alpha (LALA) survey. The survey has identified a sample of ~350 candidate Lya-emitting galaxies at z=4.5 in a search volume of 1.5 x 10^6 comoving Mpc^3. We targeted 25 candidates for spectroscopy; hence, the 18 confirmations presented herein suggest a selection reliability of 72%. The large equivalent widths (median W(rest)~80 A) but narrow physical widths (v < 500 km/s) of the Lya emission lines, along with the lack of accompanying high-ionization state emission lines, suggest that these galaxies are young systems powered by star formation rather than by AGN activity. Theoretical models of galaxy formation in the primordial Universe suggest that a small fraction of Lya-emitting galaxies at z=4.5 may still be nascent, metal-free objects. Indeed, we find with 90% confidence that 3 to 5 of the confirmed sources show W(rest) > 240 A, exceeding the maximum Lya equivalent width predicted for normal stellar populations. Nonetheless, we find no evidence for HeII 1640 emission in either individual or composite spectra, indicating that though these galaxies are young, they are not truly primitive, Population III objects.Comment: 12 pages, Accepted to Ap

Direct and indirect aboutness topics

We propose a definition of aboutness topicality that not only encompasses individual denoting DPs, but also indefinites. We concentrate on the interpretative effects of marking indefinites as topics: they either receive widest scope in their clause, or they are interpreted in the restrictor of an overt or covert Q-adverb. We show that in the first case they are direct aboutness topics insofar as they are the subject of a predication expressed by the comment, while in the second case they are indirect aboutness topics: they define the subject of a higher-order predication — namely the set of situations that the respective Q-adverb quantifies over