Rest Frame Optical Spectra of Lyman Break Galaxies: Other Lensing Arcs around MS1512-cB58

We have obtained near-infrared spectra of two images of the galaxy at z=2.72 which is gravitationally lensed by the foreground cluster MS1512+36. The brighter arc, cB58, is an image of only the nucleus and the southern half of the background galaxy, while the fainter image, A2, encompasses the entire background galaxy. Thus the gravitational lensing provides spatial resolution on a smaller scale than is routinely available by other methods. Our observations indicate no evidence for any systematic rotational velocity gradient across the face of this galaxy. The nucleus and outer regions of the galaxy do not differ in their gas reddening or excitation level, based on the identical Hα/5007 ratios. cB58 (which is more dominated by the nucleus) has relatively stronger continuum emission, perhaps because of a higher ratio of old to young stars, compared to the outer parts of the galaxy. A second emission line source, denoted as K1, at a slightly lower redshift was serendipitously detected in the slit. It appears to be the gravitationally lensed image of another background galaxy in the same group as cB58

Near-Infrared Observations of the Environments of Radio Quiet QSOs at z >~ 1

We present the results of an infrared survey of QSO fields at z=0.95, 0.995 and 1.5. Each z<1 field was imaged to typical continuum limits of J=20.5, Kprime=19 (5 sigma), and line fluxes of 1.3E10{-16}ergs/cm^2/s (1 sigma)in a 1% interference filter. 16 fields were chosen with z~0.95 targets, 14 with z~0.995 and 6 with z~1.5. A total area of 0.05 square degrees was surveyed, and two emission-line objects were found. We present the infrared and optical photometry of these objects. Optical spectroscopy has confirmed the redshift of one object (at z=0.989) and is consistent with the other object having a similar redshift. We discuss the density of such objects across a range of redshifts from this survey and others in the literature. We also present number-magnitude counts for galaxies in the fields of radio quiet QSOs, supporting the interpretation that they exist in lower density environments than their radio loud counterparts. The J-band number counts are among the first to be published in the J=16--20.Comment: 34 pages, including 12 figures; accepted for publication in the Ap

Infrared images of merging galaxies

Infrared imaging of interacting galaxies is especially interesting because their optical appearance is often so chaotic due to extinction by dust and emission from star formation regions, that it is impossible to locate the nuclei or determine the true stellar distribution. However, at near-infrared wavelengths extinction is considerably reduced, and most of the flux from galaxies originates from red giant stars that comprise the dominant stellar component by mass. Thus near infrared images offer the opportunity to study directly components of galactic structure which are otherwise inaccessible. Such images may ultimately provide the framework in which to understand the activity taking place in many of the mergers with high Infrared Astronomy Satellite (IRAS) luminosities. Infrared images have been useful in identifying double structures in the nuclei of interacting galaxies which have not even been hinted at by optical observations. A striking example of this is given by the K images of Arp 220. Graham et al. (1990) have used high resolution imaging to show that it has a double nucleus coincident with the radio sources in the middle of the dust lane. The results suggest that caution should be applied in the identification of optical bright spots as multiple nuclei in the absence of other evidence. They also illustrate the advantages of using infrared imaging to study the underlying structure in merging galaxies. The authors have begun a program to take near infrared images of galaxies which are believed to be mergers of disk galaxies because they have tidal tails and filaments. In many of these the merger is thought to have induced exceptionally luminous infrared emission (cf. Joseph and Wright 1985, Sanders et al. 1988). Although the optical images of the galaxies show spectacular dust lanes and filaments, the K images all have a very smooth distribution of light with an apparently single nucleus

Adaptive Optics Near-Infrared Spectroscopy of the Sgr A* Cluster

We present K-band $\lambda/\Delta\lambda$ ~ 2600 spectroscopy of five stars (K ~ 14 - 16 mag) within 0.''5 of Sgr A*, the radio source associated with the compact massive object suspected to be a 2.6 x 10$^{6}$ \msun black hole at the center of our Galaxy. High spatial resolution of ~ 0.''09, and good strehl ratios of ~ 0.2 achieved with adaptive optics on the 10-meter Keck telescope make it possible to measure moderate-resolution spectra of these stars individually for the first time. Two stars (S0-17 and S0-18) are identified as late-type stars by the detection of CO bandhead absorption in their spectra. Their absolute K magnitudes and CO bandhead absorption strengths are consistent with early K giants. Three stars (S0-1, S0-2, and S0-16), with r$_{proj}$ $<$ 0.0075 pc (~ 0.''2) from Sgr A*, lack CO bandhead absorption, confirming the results of earlier lower spectral and lower spatial resolution observations that the majority of the stars in the Sgr A* Cluster are early-type stars. The absolute K magnitudes of the early-type stars suggest that they are late O - early B main sequence stars of ages $<$ 20 Myr. The presence of young stars in the Sgr A* Cluster, so close to the central supermassive black hole, poses the intriguing problem of how these stars could have formed, or could have been brought, within its strong tidal field.Comment: 19 pages, 8 figures, 2 tables. Accepted for publication in Ap

Application of Dynamic System Identification to Timber Bridges

A method of global nondestructive evaluation for identifying local damage and decay in timber beams was developed in previous analytical studies and verified experimentally using simply supported beams in the laboratory. The method employs experimental modal analysis and an algorithm that monitors changes in modal strain energy between the mode shapes of a damaged structure with respect to the undamaged structure. A simple three-girder bridge was built and tested in a laboratory to investigate the capability and limitations of the method for detecting damage in a multimember timber structure. The laboratory tests showed that the method can correctly detect and locate a simulated pocket of decay inflicted at the end of a girder as well as detect a notch removed from the midspan of a girder. The tests showed that the method can correctly detect damage simultaneously at two locations within the bridge, but also that large magnitudes of damage at one location can mask smaller magnitudes of damage at another location. When a calibrated baseline model is used to represent the undamaged state of the bridge, the results show that the method of nondestructive evaluation is able to detect each case of inflicted damage, but with some increase in localization error

Risk assessment and predicting outcomes in patients with depressive symptoms: a review of potential role of peripheral blood based biomarkers

Depression is one of the major global health challenges and a leading contributor of health related disability and costs. Depression is a heterogeneous disorder and current methods for assessing its severity in clinical practice rely on symptom count, however this approach is unreliable and inconsistent. The clinical evaluation of depressive symptoms is particularly challenging in primary care, where the majority of patients with depression are managed, due to the presence of co-morbidities. Current methods for risk assessment of depression do not accurately predict treatment response or clinical outcomes. Several biological pathways have been implicated in the pathophysiology of depression; however, accurate and predictive biomarkers remain elusive. We conducted a systematic review of the published evidence supporting the use of peripheral biomarkers to predict outcomes in depression, using Medline and Embase. Peripheral biomarkers in depression were found to be statistically significant predictors of mental health outcomes such as treatment response, poor outcome and symptom remission; and physical health outcomes such as increased incidence of cardiovascular events and deaths, and all-cause mortality. However, the available evidence has multiple methodological limitations which must be overcome to make any real clinical progress. Despite extensive research on the relationship of depression with peripheral biomarkers, its translational application in practice remains uncertain. In future, peripheral biomarkers identified with novel techniques and combining multiple biomarkers may have a potential role in depression risk assessment but further research is needed in this area

The Smallest Mass Ratio Young Star Spectroscopic Binaries

Using high resolution near-infrared spectroscopy with the Keck telescope, we have detected the radial velocity signatures of the cool secondary components in four optically identified pre-main-sequence, single-lined spectroscopic binaries. All are weak-lined T Tauri stars with well-defined center of mass velocities. The mass ratio for one young binary, NTTS 160905-1859, is M2/M1 = 0.18+/-0.01, the smallest yet measured dynamically for a pre-main-sequence spectroscopic binary. These new results demonstrate the power of infrared spectroscopy for the dynamical identification of cool secondaries. Visible light spectroscopy, to date, has not revealed any pre-main-sequence secondary stars with masses <0.5 M_sun, while two of the young systems reported here are in that range. We compare our targets with a compilation of the published young double-lined spectroscopic binaries and discuss our unique contribution to this sample.Comment: Accepted for publication in the April, 2002, ApJ; 6 figure