122 research outputs found

    Novel Bonding technologies for wafer-level transparent packaging of MOEMS

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    Depending on the type of Micro-Electro-Mechanical System (MEMS), packaging costs are contributing up to 80% of the total device cost. Each MEMS device category, its function and operational environment will individually dictate the packaging requirement. Due to the lack of standardized testing procedures, the reliability of those MEMS packages sometimes can only be proven by taking into consideration its functionality over lifetime. Innovation with regards to cost reduction and standardization in the field of packaging is therefore of utmost importance to the speed of commercialisation of MEMS devices. Nowadays heavily driven by consumer applications the MEMS device market is forecasted to enjoy a compound annual growth rate (CAGR) above 13%, which is when compared to the IC device market, an outstanding growth rate. Nevertheless this forecasted value can drift upwards or downwards depending on the rate of innovation in the field of packaging. MEMS devices typically require a specific fabrication process where the device wafer is bonded to a second wafer which effectively encapsulates the MEMS structure. This method leaves the device free to move within a vacuum or an inert gas atmosphere.Comment: Submitted on behalf of EDA Publishing Association (http://irevues.inist.fr/EDA-Publishing

    A Pair of Compact Red Galaxies at Redshift 2.38, Immersed in a 100 kpc Scale Ly-alpha Nebula

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    We present Hubble Space Telescope (HST) and ground-based observations of a pair of galaxies at redshift 2.38, which are collectively known as 2142-4420 B1 (Francis et al. 1996). The two galaxies are both luminous extremely red objects (EROs), separated by 0.8 arcsec. They are embedded within a 100 kpc scale diffuse Ly-alpha nebula (or blob) of luminosity ~10^44 erg/s. The radial profiles and colors of both red objects are most naturally explained if they are young elliptical galaxies: the most distant yet found. It is not, however, possible to rule out a model in which they are abnormally compact, extremely dusty starbursting disk galaxies. If they are elliptical galaxies, their stellar populations have inferred masses of ~10^11 solar masses and ages of ~7x10^8 years. Both galaxies have color gradients: their centers are significantly bluer than their outer regions. The surface brightness of both galaxies is roughly an order of magnitude greater than would be predicted by the Kormendy relation. A chain of diffuse star formation extending 1 arcsec from the galaxies may be evidence that they are interacting or merging. The Ly-alpha nebula surrounding the galaxies shows apparent velocity substructure of amplitude ~ 700 km/s. We propose that the Ly-alpha emission from this nebula may be produced by fast shocks, powered either by a galactic superwind or by the release of gravitational potential energy.Comment: 33 pages, 9 figures, ApJ in press (to appear in Jun 10 issue

    Observations of the Crab Nebula and its pulsar in the far-ultraviolet and in the optical

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    We present HST/STIS far-UV observations of the Crab nebula and its pulsar. Broad, blueshifted absorption arising in the nebula is seen in C IV 1550, reaching about 2500 km/s. This can be interpreted as evidence for a fast outer shell, and we adopt a spherically symmetric model to constrain the properties of this. We find that the density appears to decrease outward in the shell. A lower limit to the mass is 0.3 solar masses with an accompanying kinetic energy of 1.5EE{49} ergs. A massive 10^{51} erg shell cannot be excluded, but is less likely if the density profile is much steeper than R^{-4} and the velocity is <6000 km/s. The observations cover the region 1140-1720 A. With the time-tag mode of the spectrograph we obtain the pulse profile. It is similar to that in the near-UV, although the primary peak is marginally narrower. Together with the near-UV data, and new optical data from NOT, our spectrum of the pulsar covers the entire region from 1140-9250 A. Dereddening the spectrum gives a flat spectrum for E(B-V)=0.52, R=3.1. This dereddened spectrum of the Crab pulsar can be fitted by a power law with spectral index alpha_{\nu} = 0.11 +/- 0.04. The main uncertainty is the amount and characteristics of the interstel- lar reddening, and we have investigated the dependence of \alpha_{\nu} on E(B-V) and R. In the extended emission covered by our 25" x 0.5" slit in the far-UV, we detect C IV 1550 and He II 1640 emission lines from the Crab nebula. Several interstellar absorption lines are detected toward the pulsar. The Ly alpha absorption indicates a column density of 3.0+/-0.5\EE{21} cm^{-2} of neutral hydrogen, which agrees well with our estimate of E(B-V)=0.52 mag. Other lines show no evidence of severe depletion of metals in atomic gas.Comment: 18 pages emulateapj style, including 10 figures. ApJ, accepte

    Potential Variations in the Interstellar N I Abundance

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    We present Far Ultraviolet Spectroscopic Explorer (FUSE) and Space Telescope Imaging Spectrograph observations of the weak interstellar N I doublet at 1160 Angstroms toward 17 high-density sight lines [N(Htot)>=10^21 cm^-2]. When combined with published data, our results reveal variations in the fractional N I abundance showing a systematic deficiency at large N(Htot). At the FUSE resolution (~20 km s^-1), the effects of unresolved saturation cannot be conclusively ruled out, although O I at 1356 Angstroms shows little evidence of saturation. We investigated the possibility that the N I variability is due to the formation of N_2 in our mostly dense regions. The 0-0 band of the c'_4 ^1Sigma^+_u - X ^1Sigma^+_g transition of N_2 at 958 Angstroms should be easily detected in our FUSE data; for 10 of the denser sight lines, N_2 is not observed at a sensitivity level of a few times 10^14 cm^-2. The observed N I variations are suggestive of an incomplete understanding of nitrogen chemistry. Based on observations made with the NASA-CNES-CSA Far Ultraviolet Spectroscopic Explorer, which is operated for NASA by the Johns Hopkins University under NASA contract NAS 5-32985, and the NASA/ESA Hubble Space Telescope, obtained from the Multimission Archive at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under the NASA contract NAS 5-26555.Comment: 12 pages, 3 figures, accepted for publication in ApJ Letter

    CalFUSE v3: A Data-Reduction Pipeline for the Far Ultraviolet Spectroscopic Explorer

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    Since its launch in 1999, the Far Ultraviolet Spectroscopic Explorer (FUSE) has made over 4600 observations of some 2500 individual targets. The data are reduced by the Principal Investigator team at the Johns Hopkins University and archived at the Multimission Archive at Space Telescope (MAST). The data-reduction software package, called CalFUSE, has evolved considerably over the lifetime of the mission. The entire FUSE data set has recently been reprocessed with CalFUSE v3.2, the latest version of this software. This paper describes CalFUSE v3.2, the instrument calibrations upon which it is based, and the format of the resulting calibrated data files.Comment: To appear in PASP; 29 pages, 13 figures, uses aastex, emulateap

    Multiwavelength Observations of the Hot DB Star PG 0112+104

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    We present a comprehensive multiwavelength analysis of the hot DB white dwarf PG 0112+104. Our analysis relies on newly-acquired FUSE observations, on medium-resolution FOS and GHRS data, on archival high-resolution GHRS observations, on optical spectrophotometry both in the blue and around Halpha, as well as on time-resolved photometry. From the optical data, we derive a self-consistent effective temperature of 31,300+-500 K, a surface gravity of log g = 7.8 +- 0.1 (M=0.52 Msun), and a hydrogen abundance of log N(H)/N(He) < -4.0. The FUSE spectra reveal the presence of CII and CIII lines that complement the previous detection of CII transitions with the GHRS. The improved carbon abundance in this hot object is log N(C)/N(He) = -6.15 +- 0.23. No photospheric features associated with other heavy elements are detected. We reconsider the role of PG 0112+104 in the definition of the blue edge of the V777 Her instability strip in light of our high-speed photometry, and contrast our results with those of previous observations carried out at the McDonald Observatory.Comment: 10 pages in emulateapj, 9 figures, accepted for publication in Ap

    Emission Line Galaxies in the STIS Parallel Survey I: Observations and Data Analysis

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    In the first three years of operation STIS obtained slitless spectra of approximately 2500 fields in parallel to prime HST observations as part of the STIS Parallel Survey (SPS). The archive contains almost 300 fields at high galactic latitude (|b|>30) with spectroscopic exposure times greater than 3000 seconds. This sample contains 220 fields (excluding special regions and requiring a consistent grating angle) observed between 6 June 1997 and 21 September 2000, with a total survey area of about 160 square arcminutes. At this depth, the SPS detects an average of one emission line galaxy per three fields. We present the analysis of these data, and the identification of 131 low to intermediate redshift galaxies detected by optical emission lines. The sample contains 78 objects with emission lines that we infer to be redshifted [OII]3727 emission at 0.43<z<1.7. The comoving number density of these objects is comparable to that of H-alpha emitting galaxies in the NICMOS parallel observations. One quasar and three probable Seyfert galaxies are detected. Many of the emission-line objects show morphologies suggestive of mergers or interactions. The reduced data are available upon request from the authors.Comment: 58 preprint pages, including 26 figures; accepted for publication in ApJ

    Terminal velocities of luminous, early-type SMC stars

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    Ultraviolet spectra from the Space Telescope Imaging Spectrograph (STIS) are used to determine terminal velocities for 11 O and B-type giants and supergiants in the Small Magellanic Cloud (SMC) from the Si IV and C IV resonance lines. Using archival data from observations with the Goddard High-Resolution Spectrograph and the International Ultraviolet Explorer telescope, terminal velocities are obtained for a further five B-type supergiants. We discuss the metallicity dependence of stellar terminal velocities, finding no evidence for a significant scaling between Galactic and SMC metallicities for Teff < 30,000 K, consistent with the predictions of radiation driven wind theory for supergiant stars. A comparison of the v∞/vescv_\infty / v_{esc} ratio between the SMC and Galactic samples, while consistent with the above statement, emphasizes that the uncertainties in the distances to galactic O-stars are a serious obstacle to a detailed comparison with theory. For the SMC sample there is considerable scatter in this ratio at a given effective temperature, perhaps indicative of uncertainties in stellar masses.Comment: 28 pages, 8 figures, accepted by ApJ; minor revisions prior to acceptanc
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