Effect of Optical Coating and Surface Treatments on Mechanical Loss in Fused Silica

We report on the mechanical loss in fused silica samples with various surface treatments and compare them with samples having an optical coating. Mild surface treatments such as washing in detergent or acetone were not found to affect the mechanical loss of flame-drawn fused silica fibers stored in air. However, mechanical contact (with steel calipers) significantly increased the loss. The application of a high-reflective optical coating of the type used for the LIGO test masses was found to greatly increase the mechanical loss of commercially polished fused silica microscope slides. We discuss the implications for the noise budget of interferometers.Comment: 7 pages, 2 figures. Accepted for publication in the Proceedings of the Third Eduardo Amaldi Conference on Gravitational Waves, July 12-16, 1999. Updated version contains a correction of Eq. 3 and an estimate for the loss angle of a LIGO coating. (Neither of these revisions are included in the version published in the conference proceedings.

lentiglobin gene therapy for transfusion dependent β thalassemia outcomes from the phase 1 2 northstar and phase 3 northstar 2 studies

Introduction Transfusion-dependent β-thalassemia (TDT) is a severe genetic disease characterized by anemia, iron overload and serious comorbidities for which gene therapy may be an effective treatment option. LentiGlobin gene therapy contains autologous CD34+ hematopoietic stem cells (HSCs) transduced ex vivo with the BB305 lentiviral vector (LVV) encoding β-globin with a T87Q substitution. Objective Evaluate the efficacy and safety of LentiGlobin in patients with TDT in the phase 1/2 Northstar (HGB-204; NCT01745120) and phase 3 Northstar-2 (HGB-207; NCT02906202) studies. Methods Patients with TDT (≥100 mL/kg/yr of red blood cells [RBCs] or ≥8 RBC transfusions/yr) received G-CSF and plerixafor for mobilization and HSCs were transduced with the BB305 LVV. Patients underwent single agent busulfan myeloablative conditioning, were infused with transduced cells, and were followed for engraftment, safety, and efficacy. Statistics are presented as median (min – max). Results As of March 7, 2018, 18 patients (12 – 35 yrs) were treated in Northstar (follow-up 32.1 [23.1 – 41.9] months) and as of May 15, 2018, 11 patients (12 – 24 yrs) were treated in Northstar-2 (follow-up 8.5 [0.3 – 16.2] months). Patients received a median cell dose of 8.0 (5.0 – 19.4) CD34+ cells × 106/kg in both studies. The median time to neutrophil and platelet engraftment in both studies was 19 (14 – 30) days and 44 (19 – 191) days, respectively; 1 patient in Northstar-2 (0.3 months follow-up) had not engrafted at time of analysis. Of 6 patients with platelet engraftment ≥ Day 60, 4 had non-serious bleeding events prior to engraftment. All 6 had intact spleens and 3/6 received G-CSF between Days 0 – 21. Both factors appeared associated with time to platelet engraftment. In Northstar, 8/10 patients with non-β0/β0 genotypes and 2/8 patients with β0/β0 genotypes achieved transfusion independence (TI; weighted average hemoglobin [Hb] ≥ 9 g/dL without RBC transfusions for ≥ 12 months). Median Hb during TI was 10.0 (9.3 – 13.1) g/dL. In Northstar-2, 7/8 patients with non-β0/β0 genotypes and ≥ 6 months follow-up stopped RBC transfusions with Hb of 11.1 – 13.3 g/dL at last visit; the first patient treated achieved TI. Non-hematologic grade ≥ 3 adverse events post-infusion in ≥ 5/29 (15%) patients were stomatitis, febrile neutropenia, and pharyngeal inflammation. Veno-occlusive liver disease attributed to busulfan occurred in 4/29 patients (Table 1). There was no transplant-related mortality, vector-mediated replication competent lentivirus, or clonal dominance. Conclusion In Northstar, 80% of patients with non-β0/β0 genotypes achieved TI and early Northstar-2 data suggest that patients can achieve near-normal Hb without transfusions. The safety profile of LentiGlobin is consistent with myeloablative busulfan conditioning. Longer time to platelet engraftment was observed in few patients, but no graft failure or deaths were reported

Evaluating visible derivative spectroscopy by varimax-rotated, principal component analysis of aerial hyperspectral images from the western basin of Lake Erie

The Kent State University (KSU) spectral decomposition method provides information about the spectral signals present in multispectral and hyperspectral images. Pre-processing steps that enhance signal to noise ratio (SNR) by 7.37–19.04 times, enables extraction of the environmental signals captured by the National Aeronautics and Space Administration (NASA) Glenn Research Center\u27s, second generation, Hyperspectral imager (HSI2) into multiple, independent components. We have accomplished this by pre-processing of Level 1 HSI2 data to remove stripes from the scene, followed by a combination of spectral and spatial smoothing to further increase the SNR and remove non-Lambertian features, such as waves. On average, the residual stochastic noise removed from the HSI2 images by this method is 5.43 ± 1.42%. The method also enables removal of a spectrally coherent residual atmospheric bias of 4.28 ± 0.48%, ascribed to incomplete atmospheric correction. The total noise isolated from signal by the method is thu

Towards an Intelligent Tutor for Mathematical Proofs

Computer-supported learning is an increasingly important form of study since it allows for independent learning and individualized instruction. In this paper, we discuss a novel approach to developing an intelligent tutoring system for teaching textbook-style mathematical proofs. We characterize the particularities of the domain and discuss common ITS design models. Our approach is motivated by phenomena found in a corpus of tutorial dialogs that were collected in a Wizard-of-Oz experiment. We show how an intelligent tutor for textbook-style mathematical proofs can be built on top of an adapted assertion-level proof assistant by reusing representations and proof search strategies originally developed for automated and interactive theorem proving. The resulting prototype was successfully evaluated on a corpus of tutorial dialogs and yields good results.Comment: In Proceedings THedu'11, arXiv:1202.453

Performance and durability of broadband antireflection coatings for thin film CdTe solar cells

Light reflection from the glass surface of a photovoltaic (PV) module is a significant source of energy loss for all types of PV devices. The reflection at the glass and air interface accounts for 4% of the total energy. Single layer antireflection coatings with sufficiently low refractive index have been used, such as those using magnesium fluoride or porous silica, but these are only effective over a narrow range of wavelengths. In this paper, the authors report on the design, deposition, and testing of multilayer broadband antireflection coatings. These coatings reduce the weighted average reflection over the wavelength range used by thin film CdTe devices to just 1.22%, resulting in a 3.6% relative increase in device efficiency. The authors have used multilayer stacks consisting of silica and zirconia layers deposited using reactive magnetron sputtering. Details of the stack design, sputter deposition process parameters, and the optical and microstructural properties of the layers are provided. Antireflection coatings on glass exposed to the outdoors must not degrade over the lifetime of the module. A comprehensive set of accelerated environmental durability tests has been carried out in accordance with IEC 61646 PV qualification tests. The durability tests confirmed no damage to the coatings or performance drop as a result of thermal cycling or damp heat. All attempts to perform pull tests resulted in either adhesive or substrate failure, with no damage to the coating itself. The coatings also passed acid attack tests. Scratch resistance, abrasion resistance, and adhesion tests have also been conducted. The optical performance of the coatings was monitored during these tests, and the coatings were visually inspected for any sign of mechanical failure. These tests provide confidence that broadband antireflection coatings are highly durable and will maintain their performance over the lifetime of the solar module. All dielectric metal-oxide multilayer coatings have better optical performance and superior durability compared with alternative single layer porous sol–gel coatings. Thin film CdTe devices are particularly problematic because the antireflection coating is applied to one side of the glass, while device layers are deposited directly on to the opposite glass surface in the superstrate configuration. In thin film CdTe production, the glass is exposed to high temperature processes during the absorber deposition and the cadmium chloride activation treatment. If glass precoated with a broadband antireflection coating is to be used, then the coating must withstand temperatures of up to 550 C. Surprisingly, our studies have shown that multilayer silica/zirconia antireflection coatings on soda lime glass remain unaffected by temperatures reaching 600 C, at which point mild crazing is observed. This is an important observation, demonstrating that low cost glass, which is preprocessed with a broadband antireflection coating, is directly useable in thin film CdTe module production

The echo-transponder electrode catheter: A new method for mapping the left ventricle

AbstractThe ability to locate catheter position in the left ventricle with respect to endocardial landmarks might enhance the accuracy of ventricular tachycardia mapping. An echotransponder system (Telectronics, Inc.) was compared with biplane fluoroscopy for left ventricular endocardial mapping. A 6F electrode catheter was modified with the addition of a piezoelectric crystal 5 mm from the tip. This crystal was connected to a transponder that received and transmitted ultrasound, resulting in a discrete artifact on the two-dimensional echocardiographic image corresponding to the position of the catheter tip.Catheters were introduced percutaneously into the left ventricle of nine anesthetized dogs. Two-dimensional echotransponder and biplane fluoroscopic images were recorded on videotape with the catheter at multiple endocardial sites. Catheter location was marked by delivering radiofrequency current to the distal electrode, creating a small endocardial lesion. Catheter location by echo-transponder and by fluoroscopy were compared with lesion location without knowledge of other data. Location by echo-transponder was 8.7 ± 5.1 mm from the center of the radiofrequency lesion versus 14 + 7.8 mm by fluoroscopy (n = 15, p = 0.023). Echo-transponder localization is more precise than is biplane fluoroscopy and may enhance the accuracy of left ventricular eledrophysiologic mapping

Radiation damage in the LHCb vertex locator

The LHCb Vertex Locator (VELO) is a silicon strip detector designed to reconstruct charged particle trajectories and vertices produced at the LHCb interaction region. During the first two years of data collection, the 84 VELO sensors have been exposed to a range of fluences up to a maximum value of approximately 45 × 1012 1 MeV neutron equivalent (1 MeV neq). At the operational sensor temperature of approximately −7 °C, the average rate of sensor current increase is 18 μA per fb−1, in excellent agreement with predictions. The silicon effective bandgap has been determined using current versus temperature scan data after irradiation, with an average value of Eg = 1.16±0.03±0.04 eV obtained. The first observation of n+-on-n sensor type inversion at the LHC has been made, occurring at a fluence of around 15 × 1012 of 1 MeV neq. The only n+-on-p sensors in use at the LHC have also been studied. With an initial fluence of approximately 3 × 1012 1 MeV neq, a decrease in the Effective Depletion Voltage (EDV) of around 25 V is observed. Following this initial decrease, the EDV increases at a comparable rate to the type inverted n+-on-n type sensors, with rates of (1.43±0.16) × 10−12 V/ 1 MeV neq and (1.35±0.25) × 10−12 V/ 1 MeV neq measured for n+-on-p and n+-on-n type sensors, respectively. A reduction in the charge collection efficiency due to an unexpected effect involving the second metal layer readout lines is observed

Functional Evolution of cis-Regulatory Modules at a Homeotic Gene in Drosophila

It is a long-held belief in evolutionary biology that the rate of molecular evolution for a given DNA sequence is inversely related to the level of functional constraint. This belief holds true for the protein-coding homeotic (Hox) genes originally discovered in Drosophila melanogaster. Expression of the Hox genes in Drosophila embryos is essential for body patterning and is controlled by an extensive array of cis-regulatory modules (CRMs). How the regulatory modules functionally evolve in different species is not clear. A comparison of the CRMs for the Abdominal-B gene from different Drosophila species reveals relatively low levels of overall sequence conservation. However, embryonic enhancer CRMs from other Drosophila species direct transgenic reporter gene expression in the same spatial and temporal patterns during development as their D. melanogaster orthologs. Bioinformatic analysis reveals the presence of short conserved sequences within defined CRMs, representing gap and pair-rule transcription factor binding sites. One predicted binding site for the gap transcription factor KRUPPEL in the IAB5 CRM was found to be altered in Superabdominal (Sab) mutations. In Sab mutant flies, the third abdominal segment is transformed into a copy of the fifth abdominal segment. A model for KRUPPEL-mediated repression at this binding site is presented. These findings challenge our current understanding of the relationship between sequence evolution at the molecular level and functional activity of a CRM. While the overall sequence conservation at Drosophila CRMs is not distinctive from neighboring genomic regions, functionally critical transcription factor binding sites within embryonic enhancer CRMs are highly conserved. These results have implications for understanding mechanisms of gene expression during embryonic development, enhancer function, and the molecular evolution of eukaryotic regulatory modules