Host Galaxies of Young Dust-Reddened Quasars

We present results on a multiwavelength campaign to identify the nature of dust-reddened Type 1 quasars. These quasars were selected by matching FIRST, 2MASS and very red optical counterparts with r' − K > 5. We find a very high fraction of Low Ionization Broad Absorption Line Quasars (LoBALs) among AGN selected with this method, perhaps a sign of quasar feedback. From X-ray observations and Balmer decrement measurements, the obscuring dust is most likely located in a cold absorber such as the host galaxy, rather than from a torus near the AGN. Hubble ACS imaging of a sub-sample of these sources showed a very high fraction of interacting and merging systems. The quasars appear to be very young in which dust from the merging galaxies is still settling in. Spitzer IRS and MIPS data show star formation signatures and deep Silicate absorption features in these objects, but overall the quasar is the dominant source in the Mid-infrared

A Note on Flux Induced Superpotentials in String Theory

Non-vanishing fluxes in M-theory and string theory compactifications induce a superpotential in the lower dimensional theory. Gukov has conjectured the explicit form of this superpotential. We check this conjecture for the heterotic string compactified on a Calabi-Yau three-fold as well as for warped M-theory compactifications on Spin(7) holonomy manifolds, by performing a Kaluza-Klein reduction.Comment: 19 pages, no figure

A multiwavlength study of PSR B0628-28: The first overluminous rotation-powered pulsar?

The ROSAT source RX J0630.8-2834 was suggested by positional coincidence to be the X-ray counterpart of the old field pulsar PSR B0628-28. This association, however, was regarded to be unlikely based on the computed energetics of the putative X-ray counterpart. In this paper we report on multiwavelength observations of PSR B0628-28 made with the ESO/NTT observatory in La Silla, the Jodrell Bank radio observatory and XMM-Newton. Although the optical observations do not detect any counterpart of RX J0630.8-2834 down to a limiting magnitude of V=26.1 mag and B=26.3 mag, XMM-Newton observations finally confirmed it to be the pulsar's X-ray counterpart by detecting X-ray pulses with the radio pulsar's spin-period. The X-ray pulse profile is characterized by a single broad peak with a second smaller peak leading the main pulse component by ~144 degree. The fraction of pulsed photons is (38 +- 7)% with no strong energy dependence in the XMM-Newton bandpass. The pulsar's X-ray spectrum is well described by a single component power law with photon index 2.63^{+0.23}_{-0.15}, indicating that the pulsar's X radiation is dominated by non-thermal emission processes. A low level contribution of thermal emission from residual cooling or from heated polar caps, cannot be excluded. The pulsar's spin-down to X-ray energy conversion efficiency is obtained to be ~16% for the radio dispersion measure inferred pulsar distance. If confirmed, PSR B0628-28 would be the first X-ray overluminous rotation-powered pulsar identified among all ~1400 radio pulsars known today.Comment: Accepted for publication in ApJ. Find a paper copy with higher resolution images at ftp://ftp.xray.mpe.mpg.de/people/web/astro-ph-0505488_rev2.pd

Laparoscopy Pneumoperitoneum Fuzzy Modeling

Abstract: Gas volume to intra-peritoneal pressure fuzzy modeling for evaluating pneumoperitoneum in videolaparoscopic surgery is proposed in this paper. The proposed approach innovates in using fuzzy logic and fuzzy set theory for evaluating the accuracy of the prognosis value in order to minimize or avoid iatrogenic injuries due to the blind needle puncture. In so doing, it demonstrates the feasibility of fuzzy analysis to contribute to medicine and health care. Fuzzy systems is employed here in synergy with artificial neural network based on backpropaga tion, multilayer perceptron architecture for building up numerical functions. Experimental data employed for analysis were collected in the accomplishment of the pneumoperitoneum in a random population of patients submitted to videolaparoscopic surgeries. Numerical results indicate that the proposed fuzzy mapping for describing the relation from the intra peritoneal pressure measures as function injected gas volumes succeeded in determinining a fuzzy model for this nonlinear system when compared to the statistical model

The Struve-Sahade effect in the optical spectra of O-type binaries I. Main-sequence systems

We present a spectroscopic analysis of four massive binary systems that are known or are good candidates to display the Struve-Sahade effect (defined as the apparent strengthening of the secondary spectrum of the binary when the star is approaching, and the corresponding weakening of the lines when it is receding). We use high resolution optical spectra to determine new orbital solutions and spectral types of HD 165052, HD 100213, HD 159176 and DH Cep. As good knowledge of the fundamental parameters of the considered systems is necessary to examine the Struve-Sahade effect. We then study equivalent width variations in the lines of both components of these binaries during their orbital cycle. In the case of these four systems, variations appear in the equivalent widths of some lines during the orbital cycle, but the definition given above can any longer be valid, since it is now clear that the effect modifies the primary spectrum as much as the secondary spectrum. Furthermore, the lines affected, and the way in which they are affected, depend on the considered system. For at least two of them (HD 100213 and HD 159176) these variations probably reflect the ellipsoidal variable nature of the system.Comment: 12 pages, 20 figures, in press A&

The Deep Lens Survey Transient Search I : Short Timescale and Astrometric Variability

We report on the methodology and first results from the Deep Lens Survey transient search. We utilize image subtraction on survey data to yield all sources of optical variability down to 24th magnitude. Images are analyzed immediately after acquisition, at the telescope and in near-real time, to allow for followup in the case of time-critical events. All classes of transients are posted to the web upon detection. Our observing strategy allows sensitivity to variability over several decades in timescale. The DLS is the first survey to classify and report all types of photometric and astrometric variability detected, including solar system objects, variable stars, supernovae, and short timescale phenomena. Three unusual optical transient events were detected, flaring on thousand-second timescales. All three events were seen in the B passband, suggesting blue color indices for the phenomena. One event (OT 20020115) is determined to be from a flaring Galactic dwarf star of spectral type dM4. From the remaining two events, we find an overall rate of \eta = 1.4 events deg-2 day-1 on thousand-second timescales, with a 95% confidence limit of \eta < 4.3. One of these events (OT 20010326) originated from a compact precursor in the field of galaxy cluster Abell 1836, and its nature is uncertain. For the second (OT 20030305) we find strong evidence for an extended extragalactic host. A dearth of such events in the R passband yields an upper 95% confidence limit on short timescale astronomical variability between 19.5 < R < 23.4 of \eta_R < 5.2. We report also on our ensemble of astrometrically variable objects, as well as an example of photometric variability with an undetected precursor.Comment: 24 pages, 12 figures, 3 tables. Accepted for publication in ApJ. Variability data available at http://dls.bell-labs.com/transients.htm

A technique for automatic real time scoring of several simultaneous sleep electroencephalograms

Automatic real-time scoring of simultaneous sleep electroencephalogram

Why is the Matrix Model Correct?

We consider the compactification of M theory on a light-like circle as a limit of a compactification on a small spatial circle boosted by a large amount. Assuming that the compactification on a small spatial circle is weakly coupled type IIA theory, we derive Susskind's conjecture that M theory compactified on a light-like circle is given by the finite $N$ version of the Matrix model of Banks, Fischler, Shenker and Susskind. This point of view provides a uniform derivation of the Matrix model for M theory compactified on a transverse torus $T^p$ for $p=0,...,5$ and clarifies the difficulties for larger values of $p$.Comment: 9 page