Physical Characterization of Warm Spitzer-observed Near-Earth Objects

Near-infrared spectroscopy of Near-Earth Objects (NEOs) connects diagnostic spectral features to specific surface mineralogies. The combination of spectroscopy with albedos and diameters derived from thermal infrared observations can increase the scientific return beyond that of the individual datasets. To that end, we have completed a spectroscopic observing campaign to complement the ExploreNEOs Warm Spitzer program that obtained albedos and diameters of nearly 600 NEOs (Trilling et al. 2010). Here we present the results of observations using the low-resolution prism mode (~0.7-2.5 microns) of the SpeX instrument on the NASA Infrared Telescope Facility (IRTF). We also include near-infrared observations of ExploreNEOs targets from the MIT-UH-IRTF Joint Campaign for Spectral Reconnaissance. Our dataset includes near-infrared spectra of 187 ExploreNEOs targets (125 observations of 92 objects from our survey and 213 observations of 154 objects from the MIT survey). We identify a taxonomic class for each spectrum and use band parameter analysis to investigate the mineralogies for the S-, Q-, and V-complex objects. Our analysis suggests that for spectra that contain near-infrared data but lack the visible wavelength region, the Bus-DeMeo system misidentifies some S-types as Q-types. We find no correlation between spectral band parameters and ExploreNEOs albedos and diameters. We find slightly negative Band Area Ratio (BAR) correlations with phase angle for Eros and Ivar, but a positive BAR correlation with phase angle for Ganymed. We find evidence for spectral phase reddening for Eros, Ganymed, and Ivar. We identify the likely ordinary chondrite type analog for a subset of our sample. Our resulting proportions of H, L, and LL ordinary chondrites differ from those calculated for meteorite falls and in previous studies of ordinary chondrite-like NEOs.Comment: 6 Tables, 9 Figure

Hospital Community Benefits After the ACA: Building on State Experience

Analyzes hospitals' requirements to conduct community health needs assessments, financial assistance and billing and collection policies, and community benefit reporting and oversight strategies. Notes implications for federal and state law and practice

Infrared Lightcurves of Near Earth Objects

We present lightcurves and derive periods and amplitudes for a subset of 38 near earth objects (NEOs) observed at 4.5 microns with the IRAC camera on the the Spitzer Space Telescope, many of them having no previously reported rotation periods. This subset was chosen from about 1800 IRAC NEO observations as having obvious periodicity and significant amplitude. For objects where the period observed did not sample the full rotational period, we derived lower limits to these parameters based on sinusoidal fits. Lightcurve durations ranged from 42 to 544 minutes, with derived periods from 16 to 400 minutes. We discuss the effects of lightcurve variations on the thermal modeling used to derive diameters and albedos from Spitzer photometry. We find that both diameters and albedos derived from the lightcurve maxima and minima agree with our previously published results, even for extreme objects, showing the conservative nature of the thermal model uncertainties. We also evaluate the NEO rotation rates, sizes, and their cohesive strengths.Comment: 16 pages, 4 figures, 3 tables, to appear in the Astrophysical Journal Supplement Serie

The Discovery of Cometary Activity in Near-Earth Asteroid (3552) Don Quixote

The near-Earth object (NEO) population, which mainly consists of fragments from collisions between asteroids in the main asteroid belt, is thought to include contributions from short-period comets as well. One of the most promising NEO candidates for a cometary origin is near-Earth asteroid (3552) Don Quixote, which has never been reported to show activity. Here we present the discovery of cometary activity in Don Quixote based on thermal-infrared observations made with the Spitzer Space Telescope in its 3.6 and 4.5 {\mu}m bands. Our observations clearly show the presence of a coma and a tail in the 4.5 {\mu}m but not in the 3.6 {\mu}m band, which is consistent with molecular band emission from CO2. Thermal modeling of the combined photometric data on Don Quixote reveals a diameter of 18.4 (-0.4/+0.3) km and an albedo of 0.03 (-0.01/+0.02), which confirms Don Quixote to be the third-largest known NEO. We derive an upper limit on the dust production rate of 1.9 kg s^-1 and derive a CO2 gas production rate of (1.1+-0.1)10^26 molecules s^-1. Spitzer IRS spectroscopic observations indicate the presence of fine-grained silicates, perhaps pyroxene rich, on the surface of Don Quixote. Our discovery suggests that CO2 can be present in near-Earth space over a long time. The presence of CO2 might also explain that Don Quixote's cometary nature remained hidden for nearly three decades.Comment: 40 pages, 8 figures, accepted by Ap

Magnetic Field Distribution and Signal Decay in Functional MRI in Very High Fields (up to 9.4 T) Using Monte Carlo Diffusion Modeling

Extravascular signal decay rate R2 or R2∗ as a function of blood oxygenation, geometry, and field strength was calculated using a Monte Carlo (MC) algorithm for a wider parameter range than hitherto by others. The relaxation rates of gradient-recalled-echo (GRE) and Hahn-spin-echo (HSE) imaging in the presence of blood vessels (ranging from capillaries to veins) have been computed for a wide range of field strengths up to 9.4T and 50% blood deoxygenation. The maximum HSE decay was found to be shifted to lower radii in higher compared to lower field strengths. For GRE, however, the relaxation rate was greatest for large vessels at any field strength. In addition, assessments of computational reliability have been carried out by investigating the influence of the time step, the Monte Carlo step procedure, boundary conditions, the number of angles between the vessel and the exterior field B0, the influence of neighboring vessels having the same orientation as the central vessel, and the number of proton spins. The results were compared with those obtained from a field distribution of the vessel computed by an analytic formula describing the field distribution of an ideal object (an infinitely long cylinder). It was found that the time step is not critical for values equal to or lower than 200 microseconds. The choice of the MC step procedure (three-dimensional Gaussian diffusion, constant one- or three-dimensional diffusion step) also failed to influence the results significantly; in contrast, the free boundary conditions, as well as taking too few angles into account, did introduce errors. Next neighbor vessels with the same orientation as the main vessel did not contribute significantly to signal decay. The total number of particles simulated was also found to play a minor role in computing R2/ R2∗

Carbamazepine and the active epoxide metabolite are effectively cleared by hemodialysis followed by continuous venovenous hemodialysis in an acute overdose

Hemodialysis (HD) and continuous venovenous hemodialysis (CVVHD) have an unproven role in the management of carbamazepine overdose. Albumin‐enhanced CVVHD may accelerate carbamazepine (CBZ) clearance, but no pharmacokinetic data has been reported for traditional CVVHD without albumin enhancement. In addition, it is unclear whether the active CBZ‐epoxide metabolite is removed with either mode of dialysis. We present a case of CBZ intoxication successfully managed with sequential HD and CVVHD. The CBZ half‐life during CVVHD was 14.7 hours, compared with the patient's endogenous half‐life of 30.8 hours. The CBZ‐epoxide half‐life was 3.2 hours during HD. We conclude that HD and CVVHD provide effective clearance of CBZ and the epoxide metabolite and should be considered in the management of an acute toxic ingestion.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/86953/1/j.1542-4758.2011.00563.x.pd

Preserving Derivative Information while Transforming Neuronal Curves

The international neuroscience community is building the first comprehensive atlases of brain cell types to understand how the brain functions from a higher resolution, and more integrated perspective than ever before. In order to build these atlases, subsets of neurons (e.g. serotonergic neurons, prefrontal cortical neurons etc.) are traced in individual brain samples by placing points along dendrites and axons. Then, the traces are mapped to common coordinate systems by transforming the positions of their points, which neglects how the transformation bends the line segments in between. In this work, we apply the theory of jets to describe how to preserve derivatives of neuron traces up to any order. We provide a framework to compute possible error introduced by standard mapping methods, which involves the Jacobian of the mapping transformation. We show how our first order method improves mapping accuracy in both simulated and real neuron traces under random diffeomorphisms. Our method is freely available in our open-source Python package brainlit

Monocyte/macrophage and T-cell infiltrates in peritoneum of patients with ovarian cancer or benign pelvic disease

BACKGROUND: We previously showed that tumor-free peritoneum of patients with epithelial ovarian cancer (EOC) exhibited enhanced expression of several inflammatory response genes compared to peritoneum of benign disease. Here, we examined peritoneal inflammatory cell patterns to determine their concordance with selected enhanced genes. METHODS: Expression patterns of selected inflammatory genes were mined from our previously published data base. Bilateral pelvic peritoneal and subjacent stromal specimens were obtained from 20 women with EOC and 7 women with benign pelvic conditions. Sections were first stained by indirect immunoperoxidase and numbers of monocytes/macrophages (MO/MA), T cells, B cells, and NK cells counted. Proportions of CD68+ cells and CD3+ cells that coexpressed MO/MA differentiation factors (CD163, CCR1, CXCR8, VCAM1, and phosphorylated cytosolic phospholipase A(2 )[pcPLA(2)]), which had demonstrated expression in EOC peritoneal samples, were determined by multicolor immunofluorescence. RESULTS: MO/MA were present on both sides of the pelvic peritoneum in EOC patients, with infiltration of the subjacent stroma and mesothelium. CD68+ MO/MA, the most commonly represented population, and CD3+ T cells were present more often in EOC than in benign pelvic tumors. NK cells, B cells, and granulocytes were rare. CXCL8 (IL-8) and the chemokine receptor CCR1 were coexpressed more frequently on MO/MA than on CD3+ cells contrasting with CD68+/CD163+ cells that coexpressed CXCL8 less often. An important activated enzyme in the eicosanoid pathway, pcPLA(2), was highly expressed on both CD68+ and CD163+ cells. The adherence molecule Vascular Cell Adhesion Molecule-1 (VCAM1) was expressed on CD31+ endothelial cells and on a proportion of CD68+ MO/MA but rarely on CD3+ cells. CONCLUSION: The pelvic peritoneum in EOC exhibits a general pattern of chronic inflammation, represented primarily by differentiated MO/MA, and distinct from that in benign conditions concordant with previous profiling results