1,534 research outputs found

    COLD GASS, an IRAM Legacy Survey of Molecular Gas in Massive Galaxies: III. Comparison with semi-analytic models of galaxy formation

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    We compare the semi-analytic models of galaxy formation of Fu et al. (2010), which track the evolution of the radial profiles of atomic and molecular gas in galaxies, with gas fraction scaling relations derived from the COLD GASS survey (Saintonge et al 2011). The models provide a good description of how condensed baryons in galaxies with gas are partitioned into stars, atomic and molecular gas as a function of galaxy stellar mass and surface density. The models do not reproduce the tight observed relation between stellar surface density and bulge-to-disk ratio for this population. We then turn to an analysis of the"quenched" population of galaxies without detectable cold gas. The current implementation of radio-mode feedback in the models disagrees strongly with the data. In the models, gas cooling shuts down in nearly all galaxies in dark matter halos above a mass of 10**12 M_sun. As a result, stellar mass is the observable that best predicts whether a galaxy has little or no neutral gas. In contrast, our data show that quenching is largely independent of stellar mass. Instead, there are clear thresholds in bulge-to-disk ratio and in stellar surface density that demarcate the location of quenched galaxies. We propose that processes associated with bulge formation play a key role in depleting the neutral gas in galaxies and that further gas accretion is suppressed following the formation of the bulge, even in dark matter halos of low mass.Comment: 12 figures, accepted for publication in MNRAS, the COLD GASS data is available at http://www.mpa-garching.mpg.de/COLD_GASS/data.shtm

    Morphologic Spectrum of Renal Cell Carcinoma, Unclassified: An Analysis of 136 Cases

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    Aims Renal cell carcinoma, unclassified (RCCU) is a category that includes a morphologically and biologically heterogeneous group of tumors that are unable to be diagnosed as other well-defined entities. We aim to describe the morphologic findings of tumors within this category and to determine the most frequent morphologic features leading to classification difficulty. Methods and results One hundred and thirty-six cases of RCCU were examined. Patients ranged in age from 23 to 87 years. Seventy-seven patients were men and 59 were women. International Society of Urological Pathology (ISUP) grade was most commonly 3 (n=66), followed by 2 (n=42) and 4 (n=28). Tumor size ranged from 0.6 cm to 24.9 cm. The AJCC pathologic T categories included pT1a (n=50), pT1b (n=14), pT2a (n=7), pT2b (n=4), pT3a (n=50), and pT4 (n=9). Forty-four cases included lymph node(s), of which 41% (n=18) had metastases. Tumors were assessed for a variety of histologic features and assigned to the following morphologic groups: predominantly oncocytoma/chromophobe RCC-like; clear cell RCC-like; papillary RCC-like; collecting duct-like; and pure sarcomatoid differentiation. The majority of the oncocytoma/chromophobe and clear cell RCC-like phenotypes were low stage (pT1 or pT2). The papillary RCC-like, collecting duct-like, and pure sarcomatoid phenotypes were mostly high stage (pT3 or pT4). Conclusions RCCU is a term that encompasses tumors with a variety of morphologic features and a wide biologic spectrum. The most common source of diagnostic difficulty was tumors composed of predominantly eosinophilic cells

    High-efficiency and high-power vertical-cavity surface-emitting laser designed for cryogenic applications

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    Includes bibliographical references.We report the first vertical-cavity surface-emitting laser (VCSEL) that has been optimized for cryogenic applications near 77 K, with superior characteristics that include a high output power (Pout = 22 mW at I = 25 mA), high power conversion efficiency (ηd = 32%), low threshold voltage (Vth = 1.75 V) and current (Ith = 1.7 mA), and low power dissipation (9 mW at Pout = 2.0 mW) for a 20-μm-diameter device.This work was supported in part by AFOSR and the DOE under Contract No. DE-AC04-94AL85000

    Renal Cell Carcinoma with Angioleiomyoma-Like Stroma and Clear Cell Papillary Renal Cell Carcinoma: Exploring SDHB Protein Immunohistochemistry and the Relationship to Tuberous Sclerosis Complex

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    Renal cell carcinoma (RCC) with angioleiomyoma-like stroma appears to be molecularly distinct from clear cell RCC; however, its relationship to clear cell papillary RCC remains debated. Recent studies have found that similar tumors sometimes occur in patients with tuberous sclerosis complex (TSC), of which one study found unexpectedly negative succinate dehydrogenase (SDH) B immunostaining. We evaluated immunohistochemistry for SDHB in 12 apparently sporadic RCCs with angioleiomyoma-like stroma and correlated with clinical information for stigmata of TSC. Tumors were compared to a group of 16 clear cell papillary RCCs and 6 unclassified tumors with prominent stroma. With exception of 1 unclassified tumor, all exhibited at least focal cytoplasmic staining for SDHB protein, often requiring high magnification and better appreciated with increased antibody concentration. Detailed history information was available for 9/12 patients with smooth muscle-rich tumors, revealing no stigmata of undiagnosed TSC. Electron microscopy performed on 1 of these tumors revealed mitochondria to be very sparse, potentially accounting for the weak immunohistochemical labeling for SDHB protein. Weak SDHB immunostaining may represent another shared feature of RCC with angioleiomyoma-like stroma and clear cell papillary RCC, likely due to sparse mitochondria, strengthening the possible relationship of these entities. Although smooth muscle-rich tumors have been recently reported in patients with TSC, absence of staining in tumors with this pattern may not be specific for TSC. In tumors with pale or clear cytoplasm, immunohistochemical staining for SDHB should be interpreted with caution as evidence of abnormality in the SDH pathway

    Dications of 3-Phenyl-indenylidene Dibenzo[ a.d ]cycloheptene: The Role of Charge in the Antiaromaticity of Cationic Systems

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    Dications of 9-(3-phenyl-1H-inden-1-ylidene)-5H-dibenzo[a,d]cycloheptene, 52+, were prepared by oxidation with SbF5 in SO2ClF, and their magnetic behavior was compared to dications of 9-(3-phenyl-1H-inden-1-ylidene)-9H-fluorene, 22+. The good correlation between the experimental 1H NMR shifts for the dications that were oxidized cleanly and the chemical shifts calculated by the GAIO method supported the use of the nucleus independent chemical shifts, NICS, to evaluate the antiaromaticity of the indenyl systems of 22+/52+ and their unsubstituted parent compounds, 62+ and 72+, as well as the antiaromaticity of the fluorenyl system of 22+/72+ and the aromaticity of the dibenzotropylium system of 52+/62+. Antiaromaticity was shown to be directly related to the amount of charge in the antiaromatic systems, with the antiaromatic systems more responsive to changes in the calculated NBO charge than the aromatic systems. The antiaromaticity was also shown to be directly related to the amount of delocalization in the ring system. The aromaticity of the dibenzotropylium system was much less responsive to changes in the amount of charge in the tropylium system, because the aromatic system was much more completely delocalized. Thus, antiaromatic species are more sensitive probes of delocalization than aromatic ones

    Curriculum Guidelines for Undergraduate Programs in Data Science

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    The Park City Math Institute (PCMI) 2016 Summer Undergraduate Faculty Program met for the purpose of composing guidelines for undergraduate programs in Data Science. The group consisted of 25 undergraduate faculty from a variety of institutions in the U.S., primarily from the disciplines of mathematics, statistics and computer science. These guidelines are meant to provide some structure for institutions planning for or revising a major in Data Science

    Pyoderma Gangrenosum after Fat Grafting in Alloplastic Breast Reconstruction: An Unusual Outcome.

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    Pyoderma gangrenosum (PG) is a rare and painful inflammatory skin disorder that has been recently associated with breast surgery. It is commonly mistaken for postoperative ischemia or wound infection and does not show response to antibiotics or debridement. We describe the first case of post-surgical PG (PSPG) after alloplastic breast reconstruction involving fat grafting. A 47-year-old woman underwent bilateral mastectomy and 2-stage alloplastic breast reconstruction, with fat grafting from the abdomen. Two days post-surgery, she developed bilateral erythema with tender grouped pustules that progressed rapidly into necrotic ulcerations. She did not respond to antibiotics and serial debridement. Subsequent biopsy confirmed a diagnosis of PG. She was started on steroid therapy and responded well. She was discharged on a steroid regimen, local wound care, and eventually a T-cell inhibitor. Over the next 12 months, her wounds healed without surgical intervention. PSPG has been observed in a variety of reconstructive breast surgeries, but never reported in the setting of fat grafting. As PG involves subcutaneous fat, fat grafting may accelerate and exacerbate the course of disease. Treatment for PSPG includes systemic steroid therapy or other immunomodulatory agents (or both). Surgical management remains controversial, as serial debridement and reconstruction have shown to exacerbate and stimulate disease progression. A long-term follow-up is recommended to monitor for wound healing. Delayed diagnosis of PG in breast reconstruction patients can lead to severe morbidity and disfigurement. This is first case of PSPG following fat grafting in the literature
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