50 research outputs found
A piecewise deterministic scaling limit of lifted Metropolis-Hastings in the Curie-Weiss model
No full textIn Turitsyn, Chertkov and Vucelja [Phys. D 240 (2011) 410-414] a nonreversible Markov Chain Monte Carlo (MCMC) method on an augmented state space was introduced, here referred to as Lifted Metropolis-Hastings (LMH). A scaling limit of the magnetization process in the Curie-Weiss model is derived for LMH, as well as for Metropolis-Hastings (MH). The required jump rate in the high (supercritical) temperature regime equals n1/2 for LMH, which should be compared to n for MH. At the critical temperature, the required jump rate equals n3/4 for LMH and n3/2 for MH, in agreement with experimental results of Turitsyn, Chertkov and Vucelja (2011). The scaling limit of LMH turns out to be a nonreversible piecewise deterministic exponentially ergodic "zig-zag" Markov process.Statistic
A MM SPECTRAL LINE SURVEY OF SAGITTARIUS B2(N-LMH) WITH THE BIMA ARRAY AND NRAO 12 METER RADIO TELESCOPE
No full textAuthor Institution: Department of Astronomy, University of Illinois; Department of Astronomy, National Radio Astronomy Observatory; Department of Astronomy, University of IllinoisWe have initiated a 3 mm spectral line survey toward the hot molecular core Sagittarius B2(N-LMH). This is the first spectral line survey of the Sgr B2(N) region utilizing data from both an interferometer (BIMA Array) and a single-element radio telescope (NRAO 12 meter). In this survey, covering 3.6 GHz in bandwidth, we detected 237 lines (90 identified molecular transitions, 1 electronic transition, and 148 unidentified transitions). Furthermore, the data provide information that could not be obtained by either instrument alone
Performance Evaluation of a Pilot-Scale Aerobic Granular Sludge Integrated with Gravity-Driven Membrane System Treating Domestic Wastewater
No full textThis study describes a novel integration of aerobic granular sludge (AGS) with a gravity-driven membrane (GDM) system at a pilot scale with a treatment capacity of approximately 150 L per day to treat raw domestic wastewater. The treatment performance and energy consumption of the AGS-GDM system were compared to the neighboring full-scale aerobic membrane bioreactor (AeMBR), treating the same wastewater at about 4000(±500) m3 per day. The AGS-GDM system demonstrated superior nutrient (nitrogen and phosphorus) removal as compared to the AeMBR. The GDM unit was continuously supplied with AGS-treated effluent. The GDM unit started with high [ >20 L per m2 per h (LMH) ] flux, which gradually declined. The flux remained quite stable after 15 days reaching 3 LMH after 35 days without any physical or chemical cleaning. Our results suggest that AGS-GDM is a viable technology for decentralized wastewater treatment and reuse in water-scarce regions. The AGS-GDM could easily replace conventional AeMBR technology in the wastewater treatment and reclamation market.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.BT/Environmental Biotechnolog
Fouling and chemical stability study on SiC-Al2O3 ultrafiltration membrane for sodium alginate filtration under constant flux crossflow mode
No full textTrials of surface modifications using low pressure chemical vapor deposition (LPCVD) has successfully decreased the high temperature needed for the fabrication of SiC membrane from 2000°C to below 900 °C. With this great success on the reduction of the energy con-sumption, however, further studies on the chemical stability and the fouling features of this kind of membrane were necessary. In this research, experiments were done on the SiC-Al2O3 UF membrane fabricated by LPCVD to study its chemical stability in a NaClO solution and its fouling features when filtrating sodium alginate and surface water under constant flux cross-flow mode. The backwash efficiency and the fouling resistance were analysed as well to further elucidate the fouling composition. According to the results, the SiC-Al2O3 membrane coated under higher temperature (860°C) remained stable in the NaClO solution for 200 h, (1% for 100 h and then 5% for 100 h) while the membrane coated under lower temperature (750°C) showed a water permeability increase during chlorine treatment, indicating the dissolution of the SiC layer. The high temperature coated membrane (860°C) had a better antifouling ability than low temperature coated mem-brane (750°C) and the pristine membrane especially when filtrating the pure sodium alginate (SA) solution without Ca2+ under normal flux (170 LMH) or the surface water under lower flux (65 LMH). Cake filtration was observed in the fouling curves when the critical flux was not exceeded. The addition of Ca2+ into the pure SA solution resulted in the decrease of elec-trical repulsion and the increase of bridging between foulants and membrane surface. These led to the severe fouling of the high temperature coated membrane. The low temperature coated membrane had better antifouling ability than high temperature coated membrane and the pristine membrane when 2 mmol/L of Ca2+ was added. However, the backwash (back-wash flux of around 340 LMH for normal flux condition and around 195 LMH for lower flux condition) was not efficient for all the membranes and should be improved in the future ex-periments. Applied Earth Science
Quantitative Analyses of Retinal Traction Force and Metamorphopsia in Lamellar Macular Hole and Related Diseases
No full textPurpose: To investigate the involvement of retinal traction in the pathogenesis of lamellar macular hole (LMH) and related diseases based on OCT–based consensus definition.
Design: Retrospective, observational study.
Participants: Seventy-two eyes with LMH, epiretinal membrane foveoschisis (ERM-FS), or macular pseudohole (MPH).
Methods: To quantitatively evaluate the involvement and strength of retinal traction in their pathogenesis, retinal folds were visualized with en face OCT imaging, and the maximum depth of the parafoveal retinal folds (MDRF) was measured. Metamorphopsia was quantified by measuring the minimum visual angle of dotted lines needed to cause it to disappear using M-CHARTS (Inami).
Main Outcome Measures: Maximum depth of retinal folds and M-CHARTS scores.
Results: Of the 72 eyes, 26 were classified as having LMH, 25 as having ERM-FS, and 21 as having MPH. Parafoveal retinal folds were observed in 7 (26.9%) eyes with LMH, 25 (100%) with ERM-FS, and 21 (100%) with MPH. The MDRF (7.5±17.6 μm) was significantly smaller in LMH than in ERM-FS (86.3±31.4 μm) and MPH (74.5±24.6 μm) (both P
Conclusions: Retinal traction was significantly weaker in the LMH group than in the ERM-FS and MPH groups. The MDRF was significantly associated with the degree of metamorphopsia in the ERM-FS and MPH groups. These results provide insights into the diseases’ pathophysiology and treatment strategy.
Financial Disclosure(s): The author(s) have no proprietary or commercial interest in any materials discussed in this article
Quantitative Analyses of Retinal Traction Force and Metamorphopsia in Lamellar Macular Hole and Related Diseases
No full textPurpose: To investigate the involvement of retinal traction in the pathogenesis of lamellar macular hole (LMH) and related diseases based on OCT–based consensus definition.
Design: Retrospective, observational study.
Participants: Seventy-two eyes with LMH, epiretinal membrane foveoschisis (ERM-FS), or macular pseudohole (MPH).
Methods: To quantitatively evaluate the involvement and strength of retinal traction in their pathogenesis, retinal folds were visualized with en face OCT imaging, and the maximum depth of the parafoveal retinal folds (MDRF) was measured. Metamorphopsia was quantified by measuring the minimum visual angle of dotted lines needed to cause it to disappear using M-CHARTS (Inami).
Main Outcome Measures: Maximum depth of retinal folds and M-CHARTS scores.
Results: Of the 72 eyes, 26 were classified as having LMH, 25 as having ERM-FS, and 21 as having MPH. Parafoveal retinal folds were observed in 7 (26.9%) eyes with LMH, 25 (100%) with ERM-FS, and 21 (100%) with MPH. The MDRF (7.5 ± 17.6 μm) was significantly smaller in LMH than in ERM-FS (86.3 ± 31.4 μm) and MPH (74.5 ± 24.6 μm) (both P
Conclusions: Retinal traction was significantly weaker in the LMH group than in the ERM-FS and MPH groups. The MDRF was significantly associated with the degree of metamorphopsia in the ERM-FS and MPH groups. These results provide insights into the diseases’ pathophysiology and treatment strategy.
Financial Disclosure(s): The author(s) have no proprietary or commercial interest in any materials discussed in this article
Role of late maternal thyroid hormones in cerebral cortex development: An experimental model for human prematurity
No full textHypothyroxinemia affects 35-50% of neonates born prematurely (12% of births) and increases their risk of suffering neurodevelopmental alterations. We have developed an animal model to study the role of maternal thyroid hormones (THs) at the end of gestation on offspring's cerebral maturation. Pregnant rats were surgically thyroidectomized at embryonic day (E) 16 and infused with calcitonin and parathormone (late maternal hypothyroidism [LMH] rats). After birth, pups were nursed by normal rats. Pups born to LMH dams, thyroxine treated from E17 to postnatal day (P) 0, were also studied. In developing LMH pups, the cortical lamination was abnormal. At P40, heterotopic neurons were found in the subcortical white matter and in the hippocampal stratum oriens and alveus. The Zn-positive area of the stratum oriens of hippocampal CA3 was decreased by 41.5% showing altered mossy fibers' organization. LMH pups showed delayed learning in parallel to decreased phosphorylated cAMP response element-binding protein (pCREB) and phosphorylated extracellular signal-regulated kinase 1/2 (pERK1/2) expression in the hippocampus. Thyroxine treatment of LMH dams reverted abnormalities. In conclusion, maternal THs are still essential for normal offspring's neurodevelopment even after onset of fetal thyroid function. Our data suggest that thyroxine treatment of premature neonates should be attempted to compensate for the interruption of the maternal supply. © The Author 2009.Spanish MICINN Grant (PN I+D+I SAF2006-14068 and FIS 05/PI050590).Peer Reviewe
Quantitative Analyses of Retinal Traction Force and Metamorphopsia in Lamellar Macular Hole and Related Diseases
No full textPurpose: To investigate the involvement of retinal traction in the pathogenesis of lamellar macular hole (LMH) and related diseases based on OCT–based consensus definition. Design: Retrospective, observational study. Participants: Seventy-two eyes with LMH, epiretinal membrane foveoschisis (ERM-FS), or macular pseudohole (MPH). Methods: To quantitatively evaluate the involvement and strength of retinal traction in their pathogenesis, retinal folds were visualized with en face OCT imaging, and the maximum depth of the parafoveal retinal folds (MDRF) was measured. Metamorphopsia was quantified by measuring the minimum visual angle of dotted lines needed to cause it to disappear using M-CHARTS (Inami). Main Outcome Measures: Maximum depth of retinal folds and M-CHARTS scores. Results: Of the 72 eyes, 26 were classified as having LMH, 25 as having ERM-FS, and 21 as having MPH. Parafoveal retinal folds were observed in 7 (26.9%) eyes with LMH, 25 (100%) with ERM-FS, and 21 (100%) with MPH. The MDRF (7.5 ± 17.6 μm) was significantly smaller in LMH than in ERM-FS (86.3 ± 31.4 μm) and MPH (74.5 ± 24.6 μm) (both P < 0.001), whereas no significant difference in MDRF between MPH and ERM-FS was observed (P = 0.43). A significant positive correlation between MDRF and M-CHARTS scores was observed in ERM-FS and MPH (P = 0.008 and 0.040, respectively) but not in LMH (P = 0.073). Conclusions: Retinal traction was significantly weaker in the LMH group than in the ERM-FS and MPH groups. The MDRF was significantly associated with the degree of metamorphopsia in the ERM-FS and MPH groups. These results provide insights into the diseases’ pathophysiology and treatment strategy. Financial Disclosure(s): The author(s) have no proprietary or commercial interest in any materials discussed in this article
Models of diffuse Hα in the interstellar medium : the relative contributions from in situ ionization and dust scattering
No full textJB acknowledges the support of an STFC studentship. LMH acknowledges support from the US National Science Foundation through award AST-1108911.Using three-dimensional Monte Carlo radiation transfer models of photoionization and dust scattering, we explore different components of the widespread diffuse Hα emission observed in the interstellar medium of the Milky Way and other galaxies. We investigate the relative contributions of Hα from recombination emission in ionized gas and Hα that originates in HII regions near the Galactic mid-plane and scatters off high-altitude dust in the diffuse interstellar medium. For the radiation transfer simulations, we consider two geometries for the interstellar medium: a three-dimensional fractal geometry that reproduces the average density structure inferred for hydrogen in the Milky Way, and a density structure from a magnetohydrodynamic simulation of a supernova-driven turbulent interstellar medium. Although some sight lines that are close to HII regions can be dominated by scattered light, overall we find that less than ~20 per cent of the total Hα intensity in our simulations can be attributed to dust scattering. Our findings on the relative contribution of scattered Hα are consistent with previous observational and theoretical analyses. We also investigate the relative contributions of dust scattering and in situ ionization of high-density dust clouds in the diffuse gas. Dust scattering in these partially ionized clouds contribute ~40 per cent to the total intensity of Hα.Peer reviewe
A SPECTRAL LINE SURVEY OF SELECTED 3 MM BANDS TOWARD SAGITTARIUS B2(N-LMH) USING THE NRAO 12 METER RADIO TELESCOPE AND THE BIMA ARRAY II. DATA ANALYSIS
No full text Current address:NASA Goddard Space Flight Center, Earth and Space Data Computing Division, Code 930, Greenbelt, MD 20771 D. N. Friedel, L. E. Snyder, B. E. Turner, and A. Remijan, International Symposium on Molecular Spectroscopy, Talk FA03 (2003) D. N. Friedel, L. E. Snyder, B. E. Turner, and A. Remijan, ApJ 600, 243 (2004)Author Institution: Department of Astronomy, University of Illinois; Department of Astronomy, National Radio Astronomy Observatory; Department of Astronomy, University of IllinoisWe have analyzed the data from our 3 mm spectral line survey of the high mass star forming region Sagittarius , covering 3.6 GHz of bandwidth, where we detected 218 lines (97 identified molecular transitions, one recombination line, and 120 unidentified lines). The analysis was done using rotation-temperature diagrams and amplitude distributions in the plane. These methods give insight into the rotation temperature and column density of each observed species as well as the distribution on the sky. From the distribution information we can infer potential formation mechanisms for these species as well as constrain possible identifications for the unidentified transitions
