Estimating the Effects of Part Size on Direct Laser Deposition Parameter Selection via a Thermal Resistance Network Approach

A mathematical model for heat transfer during the Directed Energy Deposition (DED) process is proposed. The model employs the thermal resistance network analogy and is developed to aid one in predicting part size effects on its temperature distribution during manufacture, and in how to compensate such effects via suitable process parameter selection. The model predicts a pseudo steady-state temperature response in the melt pool. The temperature variation along the heat affected zone of a thin-walled part is estimated while assuming deposition is occurring far from the substrate. Predicted melt pool and bulk part temperatures are validated against Laser Engineering Net Shaping (LENSTM) experimental data obtained via a dual-wavelength pyrometer and in-chamber infrared camera, respectively. Results demonstrate that the model may be used to predict an average melt pool temperature. Bulk, calculated temperature distribution needs to be further investigated to find a more suitable heat transfer coefficient surrounding the part.Mechanical Engineerin

Adjunctive intravitreal dexamethasone in the treatment of acute endophthalmitis following cataract surgery

Edward F Hall1, Garrett R Scott1, David C Musch1,2, David N Zacks11Department of Ophthalmology and Visual Sciences, Medical School; 2Department of Epidemiology, School of Public Health; University of Michigan, Ann Arbor, MI, USAPurpose: Controversy exists regarding the use of intravitreal dexamethasone (IVD) as an anti-inflammatory adjunct to intravitreal antibiotics in patients with acute endophthalmitis following cataract surgery. The purpose of this project was to evaluate our experience regarding the effect of adjunctive IVD use on visual outcomes in such patients.Design: Retrospective, comparative case series.Methods: Study population: Patients treated for acute endophthalmitis following cataract surgery from 1995–2004. Intervention: In addition to standard intravitreal antibiotic treatment, some patients also received a single adjunctive injection of IVD. Primary outcome measures: Median visual acuity at last follow-up and percentage of patients achieving a ≥3-line improvement in visual acuity. Secondary outcome measures: Inflammatory index scoring, including amount of cell and flare, height of hypopyon, and presence of fibrin as a function of time after treatment.Results: Twenty-six eyes were treated with and 38 eyes without adjunctive IVD. Median presenting visual acuity was Hand Motion in both groups. Median visual acuity at last followup measured 20/40 in the IVD group and 20/50 in the No-IVD group (p = 0.75). Seventy-three percent of patients in the IVD group and 82% of patients in the No-IVD group achieved a ≥3-line improvement in visual acuity (p = 0.42). No significant difference was detected between the IVD and No-IVD groups for any of the three measures of inflammation.Conclusion: The use of IVD did not significantly improve the final median visual acuity, the chance of achieving a ≥3-line improvement in visual acuity, or the amount of intraocular inflammation. Based on these findings, and the possible detrimental effect of IVD on visual outcomes previously reported in the literature, the use of IVD does not appear to be warranted as a routine adjunctive treatment in postoperative endophthalmitis.Keywords: endophthalmitis, dexamethasone, intravitreal injectio

Background reionization history from omniscopes

The measurements of the 21-cm brightness temperature fluctuations from the neutral hydrogen at the Epoch of Reionization (EoR) should inaugurate the next generation of cosmological observables. In this respect, many works have concentrated on the disambiguation of the cosmological signals from the dominant reionization foregrounds. However, even after perfect foregrounds removal, our ignorance on the background reionization history can significantly affect the cosmological parameter estimation. In particular, the interdependence between the hydrogen ionized fraction, the baryon density and the optical depth to the redshift of observation induce nontrivial degeneracies between the cosmological parameters that have not been considered so far. Using a simple, but consistent reionization model, we revisit their expected constraints for a futuristic giant 21-cm omniscope by using for the first time Markov Chain Monte Carlo (MCMC) methods on multiredshift full sky simulated data. Our results agree well with the usual Fisher matrix analysis on the three-dimensional flat sky power spectrum but only when the above-mentioned degeneracies are kept under control. In the opposite situation, Fisher results can be inaccurate. We show that these conditions can be fulfilled by combining cosmic microwave background measurements with multiple observation redshifts probing the beginning of EoR. This allows a precise reconstruction of the total optical depth, reionization duration and maximal spin temperature. Finally, we discuss the robustness of these results in presence of unresolved ionizing sources. Although most of the standard cosmological parameters remain weakly affected, we find a significant degradation of the background reionization parameter estimation in presence of nuisance ionizing sources.Comment: 22 pages, 18 figures, uses RevTex. References added, matches published versio

Expression of hsp 27, hsp 60, hsc 70, and hsp 70 stress response genes in cultured human urothelial cells (UROtsa) exposed to lethal and sublethal concentrations of sodium arsenite.

The stress response is one mechanism that the bladder urothelium could potentially employ to protect itself from cellular damage after exposure to arsenic and, in so doing, influence the shape of the dose-response curve at low concentrations of exposure to this environmental pollutant. In the present study, we used the cultured human urothelial cell line UROtsa, a model of human urothelium, to determine the expression of heat shock proteins hsp 27, hsp 60, hsc 70, and hsp 70 after acute and extended exposure of the cells to lethal and sublethal levels of sodium arsenite (NaAsO2). Acute exposure was modeled by exposing confluent cultures of UROtsa cells to 100 micro M NaAsO2 for 4 hr followed by a 48-hr recovery period. Extended exposure was modeled by exposing confluent UROtsa cells to 1, 4, and 8 micro M NaAsO2 for 16 days, with the highest concentration producing cell death by 4 days of exposure. The expression of hsp 27, hsp 60, hsc 70, and hsp 70 mRNA and protein was determined by reverse-transcription polymerase chain reaction and Western analysis. Cell viability was determined by the MTT [(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay. The results demonstrated that the expression of hsp 27, hsp 60, and hsc 70 mRNA and protein were not consistently increased by either acute or extended exposure to NaAsO2. In contrast, hsp 70 expression was induced by NaAsO2 after both acute and extended exposure. The degree and duration of the induction of the hsp 70 protein in the extended time course of exposure to NaAsO2 correlated directly with UROtsa cell cytotoxicity. The substantial level of basal expression of hsp 27, hsp 60, and hsc 70 shown previously in human bladder urothelium, coupled with the inducible expression of hsp 70, could provide the human urothelium with a mechanism to withstand and recover from a low level of arsenite exposure

Binding of Ribosomal Proteins to RNA Covalently Coupled to Agarose

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65486/1/j.1432-1033.1977.tb11554.x.pd

The Micro-Jansky Sky at 8.4 GHz

We present the results from two radio integrations at 8.4 GHz using the VLA. One of the fields, at 13h,+43d (SA13 field), has an rms noise level of 1.49 microJy and is the deepest radio image yet made. Thirty-four sources in a complete sample were detected above 7.5 microJy and 25 are optically identified to a limit of I=25.8, using our deep HST and ground-based images. The radio sources are usually located within 0.5" (typically 5 kpc) of a galaxy nucleus, and generally have a diameter less than 2.5". The second field at 17h, +50d (Hercules Field) has an rms noise of 35 microJy and contains 10 sources. We have also analyzed a complete flux density-limited sample at 8.4 GHz of 89 sources from five deep radio surveys, including the Hubble deep field. Half of all the optical counterparts are with galaxies brighter than I=23 mag, but 20% are fainter than I=25.5 mag. We confirm the tendency for the micro-Jansky radio sources to prefer multi-galaxy systems. The distribution of the radio spectral index between 1.4 and 8.4 GHz peaks at alpha = -0.75~ with a median value of -0.6. The average spectral index becomes steeper (lower values) for sources below 35 microJy, and for sources identified with optical counterparts fainter than I=25.5 mag. The differential radio count between 7.5 and 1000 microJy has a slope of -2.11 +/-0.13 and a surface density of 0.64 sources per square-arcmin with flux density greater than $7.5 microJy.Comment: 21 pages, 8 figure

Observations and Theoretical Implications of the Large Separation Lensed Quasar SDSS J1004+4112

We study the recently discovered gravitational lens SDSS J1004+4112, the first quasar lensed by a cluster of galaxies. It consists of four images with a maximum separation of 14.62''. The system has been confirmed as a lensed quasar at z=1.734 on the basis of deep imaging and spectroscopic follow-up observations. We present color-magnitude relations for galaxies near the lens plus spectroscopy of three central cluster members, which unambiguously confirm that a cluster at z=0.68 is responsible for the large image separation. We find a wide range of lens models consistent with the data, but they suggest four general conclusions: (1) the brightest cluster galaxy and the center of the cluster potential well appear to be offset by several kpc; (2) the cluster mass distribution must be elongated in the North--South direction, which is consistent with the observed distribution of cluster galaxies; (3) the inference of a large tidal shear (~0.2) suggests significant substructure in the cluster; and (4) enormous uncertainty in the predicted time delays between the images means that measuring the delays would greatly improve constraints on the models. We also compute the probability of such large separation lensing in the SDSS quasar sample, on the basis of the CDM model. The lack of large separation lenses in previous surveys and the discovery of one in SDSS together imply a mass fluctuation normalization \sigma_8=1.0^{+0.4}_{-0.2} (95% CL), if cluster dark matter halos have an inner slope -1.5. Shallower profiles would require higher values of \sigma_8. Although the statistical conclusion might be somewhat dependent on the degree of the complexity of the lens potential, the discovery is consistent with the predictions of the abundance of cluster-scale halos in the CDM scenario. (Abridged)Comment: 21 pages, 24 figures, 5 tables, accepted for publication in Ap