Characteristics of the Menstrual Cycle After Discontinuation of Oral Contraceptives

Background: Menstrual cycle function may continue to be altered after discontinuation of oral contraceptives (OC). Few studies have been published on the effects of recent OC use on menstrual cycle parameters; none have examined characteristics of the menstrual flow or the quality of cervical mucus. The purpose of this retrospective matched cohort study is to assess biomarkers of the menstrual cycle after discontinuation of OCs. Methods: Among a sample of women who daily recorded observations of menstrual cycle biomarkers, 70 women who had recently discontinued OCs were randomly matched by age and parity with 70 women who had not used OCs for at least 1 year. Outcomes investigated included overall cycle length, length of the luteal phase, estimated day of ovulation, duration of menstrual flow, menstrual intensity, and mucus score. Differences between recent OC users and controls were assessed using random effects modeling. Results: Recent OC users had statistically significantly lower scores for mucus quality for cycles 1 and 2. Additionally, OC users had a later estimated day of ovulation that was statistically significant in cycle 2 and a decreased intensity of menstrual flow that was significant in the first four cycles (difference = −0.48 days). In random effects modeling, all these parameters were significantly different for the first six cycles combined. Conclusions: Menstrual cycle biomarkers are altered for at least two cycles after discontinuation of OCs, and this may help explain the temporary decrease in fecundity associated with recent OC use

SPICES II. Optical and Near-Infrared Identifications of Faint X-Ray Sources from Deep Chandra Observations of Lynx

We present our first results on field X-ray sources detected in a deep, 184.7 ks observation with the ACIS-I camera on Chandra. The observations target the Lynx field of SPICES, and contains three known X-ray-emitting clusters out to z=1.27. Not including the known clusters, in the 17'x17' ACIS-I field we detect 132 sources in the 0.5-2 keV (soft) X-ray band down to a limiting flux of \~1.7e-16 erg/cm2/s and 111 sources in the 2-10 keV (hard) X-ray band down to a limiting flux of ~1.3e-15 erg/cm2/s. The combined catalog contains a total of 153 sources, of which 42 are detected only in the soft band and 21 are detected only in the hard band. Confirming previous Chandra results, we find that the fainter sources have harder X-ray spectra, providing a consistent solution to the long-standing `spectral paradox'. From deep optical and near-infrared follow-up data, 77% of the X-ray sources have optical counterparts to I=24 and 71% of the X-ray sources have near-infrared counterparts to K=20. Four of the 24 sources in the near-IR field are associated with extremely red objects (EROs; I-K>4). We have obtained spectroscopic redshifts with the Keck telescopes of 18 of the Lynx Chandra sources. These sources comprise a mix of broad-lined active galaxies, apparently normal galaxies, and two late-type Galactic dwarfs. Intriguingly, one Galactic source is identified with an M7 dwarf exhibiting non-transient, hard X-ray emission. We review non-AGN mechanisms to produce X-ray emission and discuss properties of the Lynx Chandra sample in relation to other samples of X-ray and non-X-ray sources.Comment: 42 pages, 16 figures. Accepted for publication in the May 2002 Astronomical Journa

First Results from the SPICES Survey

We present first results from SPICES, the Spectroscopic, Photometric, Infrared-Chosen Extragalactic Survey. SPICES is comprised of four ~30 square arcminute high Galactic latitude fields with deep BRIzJK imaging reaching depths of ~25th magnitude (AB) in the optical and ~23rd magnitude (AB) in the near-infrared. To date we have 626 spectroscopic redshifts for infrared-selected SPICES sources with K<20 (Vega). The project is poised to address galaxy formation and evolution to redshift z~2. We discuss initial results from the survey, including the surface density of extremely red objects and the fraction of infrared sources at z>1. One of the SPICES fields has been the target of a deep 190 ksec Chandra exposure; we discuss initial results from analysis of that data set. Finally, we briefly discuss a successful campaign to identify high-redshift sources in the SPICES fields.Comment: 5 pages, 2 figures; to appear in the proceedings of the ESO/ECF workshop on "Deep Fields", 9-12 Oktober 2000, Garchin

Discovery of a Radio-Selected z ~ 6 Quasar

We present the discovery of only the second radio-selected, z ~ 6 quasar. We identified SDSS J222843.54+011032.2 (z=5.95) by matching the optical detections of the deep Sloan Digital Sky Survey (SDSS) Stripe 82 with their radio counterparts in the Stripe82 VLA Survey. We also matched the Canadian-France-Hawaiian Telescope Legacy Survey Wide (CFHTLS Wide) with the Faint Images of the Radio Sky at Twenty-cm (FIRST) survey but have yet to find any z ~ 6 quasars in this survey area. The discovered quasar is optically-faint, z = 22.3 and M_{1450} ~ -24.5, but radio-bright, with a flux density of f$_{1.4GHz, peak}$ = 0.31mJy and a radio-loudness of R ~ 1100 (where R = f_{5GHz}/f_{2500}). The i-z color of the discovered quasar places it outside the color selection criteria for existing optical surveys. We conclude by discussing the need for deeper wide-area radio surveys in the context of high-redshift quasars.Comment: 20 pages, 6 figures, and ApJ accepte

Chandra Detection of a TypeII Quasar at z=3.288

We report on observations of a TypeII quasar at redshift z=3.288, identified as a hard X-ray source in a 185 ks observation with the Chandra X-ray Observatory and as a high-redshift photometric candidate from deep, multiband optical imaging. CXOJ084837.9+445352 (hereinafter CXO52) shows an unusually hard X-ray spectrum from which we infer an absorbing column density N(H) = (4.8+/-2.1)e23 / cm2 (90% confidence) and an implied unabsorbed 2-10 keV rest-frame luminosity of L(2-10) = 3.3e44 ergs/s, well within the quasar regime. Hubble Space Telescope imaging shows CXO52 to be elongated with slight morphological differences between the WFPC2 F814W and NICMOS F160W bands. Optical and near-infrared spectroscopy of CXO52 show high-ionization emission lines with velocity widths ~1000 km/s and flux ratios similar to a Seyfert2 galaxy or radio galaxy. The latter are the only class of high-redshift TypeII luminous AGN which have been extensively studied to date. Unlike radio galaxies, however, CXO52 is radio quiet, remaining undetected at radio wavelengths to fairly deep limits, f(4.8GHz) < 40 microJy. High-redshift TypeII quasars, expected from unification models of active galaxies and long-thought necessary to explain the X-ray background, are poorly constrained observationally with few such systems known. We discuss recent observations of similar TypeII quasars and detail search techniques for such systems: namely (1) X-ray selection, (2) radio selection, (3) multi-color imaging selection, and (4) narrow-band imaging selection. Such studies are likely to begin identifying luminous, high-redshift TypeII systems in large numbers. We discuss the prospects for these studies and their implications to our understanding of the X-ray background.Comment: 28 pages, 5 figures; to appear in The Astrophysical Journa

The Unusual Infrared Object HDF-N J123656.3+621322

We describe an object in the Hubble Deep Field North with very unusual near-infrared properties. It is readily visible in Hubble Space Telescope NICMOS images at 1.6um and from the ground at 2.2um, but is undetected (with signal-to-noise <~ 2) in very deep WFPC2 and NICMOS data from 0.3 to 1.1um. The f_nu flux density drops by a factor >~ 8.3 (97.7% confidence) from 1.6 to 1.1um. The object is compact but may be slightly resolved in the NICMOS 1.6um image. In a low-resolution, near-infrared spectrogram, we find a possible emission line at 1.643um, but a reobservation at higher spectral resolution failed to confirm the line, leaving its reality in doubt. We consider various hypotheses for the nature of this object. Its colors are unlike those of known galactic stars, except perhaps the most extreme carbon stars or Mira variables with thick circumstellar dust shells. It does not appear to be possible to explain its spectral energy distribution as that of a normal galaxy at any redshift without additional opacity from either dust or intergalactic neutral hydrogen. The colors can be matched by those of a dusty galaxy at z >~ 2, by a maximally old elliptical galaxy at z >~ 3 (perhaps with some additional reddening), or by an object at z >~ 10 whose optical and 1.1um light have been suppressed by the intergalactic medium. Under the latter hypothesis, if the luminosity results from stars and not an AGN, the object would resemble a classical, unobscured protogalaxy, with a star formation rate >~ 100 M_sun/yr. Such UV-bright objects are evidently rare at 2 < z < 12.5, however, with a space density several hundred times lower than that of present-day L* galaxies.Comment: Accepted for publication in the Astrophysical Journal. 27 pages, LaTeX, with 7 figures (8 files); citations & references updated + minor format change

Stellar Masses of Lyman Break Galaxies, Lyman Alpha Emitters and Radio Galaxies in Overdense Regions at z=4-6

We present new information on galaxies in the vicinity of luminous radio galaxies and quasars at z=4,5,6. These fields were previously found to contain overdensities of Lyman Break Galaxies (LBGs) or spectroscopic Lyman alpha emitters. We use HST and Spitzer data to infer stellar masses, and contrast our results with large samples of LBGs in more average environments as probed by the Great Observatories Origins Deep Survey (GOODS). The following results were obtained. First, LBGs in both overdense regions and in the field at z=4-5 lie on a very similar sequence in a z'-[3.6] versus [3.6] color-magnitude diagram. This is interpreted as a sequence in stellar mass (log[M*/Msun] = 9-11) in which galaxies become increasingly red due to dust and age as their star formation rate (SFR) increases. Second, the two radio galaxies are among the most massive objects (log[M*/Msun]~11) known to exist at z~4-5, and are extremely rare based on the low number density of such objects as estimated from the ~25x larger area GOODS survey. We suggest that the presence of these massive galaxies and supermassive black holes has been boosted through rapid accretion of gas or merging inside overdense regions. Third, the total stellar mass found in the z=4 ``proto-cluster'' TN1338 accounts for <30% of the stellar mass on the cluster red sequence expected to have formed at z>4, based on a comparison with the massive X-ray cluster Cl1252 at z=1.2. Although future near-infrared observations should determine whether any massive galaxies are currently being missed, one possible explanation for this mass difference is that TN1338 evolves into a smaller cluster than Cl1252. This raises the interesting question of whether the most massive protocluster regions at z>4 remain yet to be discovered.Comment: The Astrophysical Journal, In Press (17 pages, 7 figures

SeaWiFS Technical Report Series

Two issues regarding primary productivity, as it pertains to the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) Program and the National Aeronautics and Space Administration (NASA) Mission to Planet Earth (MTPE) are presented in this volume. Chapter 1 describes the development of a science plan for deriving primary production for the world ocean using satellite measurements, by the Ocean Primary Productivity Working Group (OPPWG). Chapter 2 presents discussions by the same group, of algorithm classification, algorithm parameterization and data availability, algorithm testing and validation, and the benefits of a consensus primary productivity algorithm