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231 results on '"Bohn J"'

1. Enhancing nonlinear optics in thin materials

Author

Bohn, J., Hendry, Euan, and Barnes, William

Abstract

This thesis examines various nonlinear optical processes to either control the frequency or switch the amplitude of light all-optically. This is achieved in subwavelength thin samples designed to overcome issues such as phase-matching. In order to achieve a significant nonlinear optical response, we utilise plasmonic resonances and nano-antennas. First, we enhance the high-harmonic generation in graphene. A heterostructure of gold nano-ribbons on graphene with a thin insulator in-between enhances the incoming electric field and enormously enhances the high-harmonic generation. A thousandfold enhancement of the fifth-harmonic generations is measured. Next, we study the all-optical switching of an epsilon-near-zero plasmon in indium tin oxide (ITO). The resonance provides near-perfect absorption and occurs for layers of just 60 nm thickness. Utilising the Kretschmann-geometry in a pump-probe scheme enables phase-matching to the resonance and studying the nonlinear changes of the reflection. Significant absolute changes of 45 % are measured, with an initial reflection of ~1 % thanks to the near-perfect absorption resonance. A novel two-beam coupling contribution is identified and will be essential to take into account in other studies. The addition of cross-shaped nano-antennas allows for improvement on various critical issues. Optical switching is now possible for lower intensities, normal incidence and better control of polarisation. The symmetric cross-shape enables a nonlinear dichroic response by which only the probe polarisation parallel to the pumped cross-bar is undergoing a significant nonlinear shift. We analyse the complete polarisation ellipses and identify two wavelength regimes in which the amplitude or phase can be modulated independently. Finally, we study the angle and frequency-dependent phase-modulation in ITO films of various thicknesses. We present good agreement with the temporal refraction for low angle of incidence. However, we find an additional dependence for higher angles. Close to the epsilon-near-zero case, we even report an opposing frequency shifting contribution. We show that the additional phase contribution origins from the temporal changes to the spatial refractive index boundary. Hence, we refer to the process as spatiotemporal refraction. This contribution can tailor the frequency shift and allow for better designability of simultaneous ultrafast changes in amplitude and phase. In summary, both graphene and ITO have proven themselves as useful nonlinear active media. The enhanced response makes them promising materials for controlling frequency and amplitude in applications such as optical communication. Beyond that, the work on ITO even unveils novel effects such as spatiotemporal refraction.

Published
2022

2. The fast non-ferric kicker system for the Muon [formula omitted] Experiment at Fermilab

Author

Schreckenberger, A.P., Allspach, D., Barak, D., Bohn, J., Bradford, C., Cauz, D., Chang, S.P., Chapelain, A., Chappa, S., Charity, S., Chislett, R., Esquivel, J., Ferrari, C., Fioretti, A., Gabbanini, C., Galati, M.D., Gibbons, L., Holzbauer, J.L., Incagli, M., Jensen, C., Kaspar, J., Kawall, D., Keshavarzi, A., Kessler, D.S., Kiburg, B., Krafczyk, G., Madrak, R., Mikhailichenko, A.A., Nguyen, H., Overhage, K., Park, S., Pfeffer, H., Polly, C.C., Popovic, M., Rivera, R., Roberts, B.L., Rubin, D., Semertzidis, Y.K., Stapleton, J., Stoughton, C., Voirin, E., and Wolff, D.

Published
2021
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7. The fast non-ferric kicker system for the Muon $g-2$ Experiment at Fermilab

Author

Schreckenberger, A. P., Allspach, D., Barak, D., Bohn, J., Bradford, C., Cauz, D., Chang, S. P., Chapelain, A., Chappa, S., Charity, S., Chislett, R., Esquivel, J., Ferrari, C., Fioretti, A., Gabbanini, C., Galati, M. D., Gibbons, L., Holzbauer, J. L., Incagli, M., Jensen, C., Kaspar, J., Kawall, D., Keshavarzi, A., Kessler, D. S., Kiburg, B., Krafczyk, G., Madrak, R., Mikhailichenko, A. A., Nguyen, H., Overhage, K., Park, S., Pfeffer, H., Polly, C. C., Popovic, M., Rivera, R., Roberts, B. L., Rubin, D., Semertzidis, Y. K., Stapleton, J., Stoughton, C., Voirin, E., and Wolff, D.

Subjects
Kickers, Physics - Instrumentation and Detectors, Beam storage, Fermilab, Muon g−2, Pulsed high-voltage, Physics::Instrumentation and Detectors, FOS: Physical sciences, Instrumentation and Detectors (physics.ins-det), High Energy Physics - Experiment, High Energy Physics - Experiment (hep-ex), Physics::Accelerator Physics, High Energy Physics::Experiment
Abstract

We describe the installation, commissioning, and characterization of the new injection kicker system in the Muon $g-2$ Experiment (E989) at Fermilab, which makes a precision measurement of the muon magnetic anomaly. Three Blumlein pulsers drive each of the 1.27-m-long non-ferric kicker magnets, which reside in a storage ring vacuum (SRV) that is subjected to a 1.45 T magnetic field. The new system has been redesigned relative to Muon $g-2$'s predecessor experiment, and we present those details in this manuscript.

Published
2021

10. Structure and Properties of Glassy Polymers

Author

MARTIN R. TANT, ANITA J. HILL, Anita J. Hill, Martin R. Tant, Edmund A. Di Marzio, C. A. Angell, Jörg Baschnagel, K.-P. Bohn, J. K. Krüger, N. Haralampus, J. P. Northrop, C. Scordalakes, E. Ashmore, W. Martin, D. Kranbuehl, P. H. Verdier, Bernhard Wunderlich, Iwao Okazaki, Robert Simha, Christopher

Published
1999

19. Safety of acalabrutinib treatment in very old (≥80 y) and/or frail patients with chronic lymphocytic leukemia ‐ interim safety analysis of the ongoing phase II CLL‐Frail trial.

Author

Simon, F., Ligtvoet, R., Nösslinger, T., Bohn, J., von Tresckow, J., Liersch, R., Gaska, T., Jentsch‐Ullrich, K., Koenigsmann, M., Wolff, T., Schwaner, I., Wolf, D., Schneider, C., Tausch, E., Stilgenbauer, S., Kreuzer, K., Robrecht, S., Fink, A., Fürstenau, M., and Fischer, K.

Subjects
CHRONIC lymphocytic leukemia
Abstract

B Introduction: b BTK-inhibitors have revolutionized treatment of CLL. Hoffmann-La Roche Ltd., Gilead, Janssen, Adapative Biotechnologies, Hexal Research funding: Abbvie, Beigene, AstraZeneca, Fa. Hoffmann-La Roche Ltd., Gilead, Janssen Educational grants: Abbvie, Beigene, AstraZeneca, Novartis, Celgene, Fa. [Extracted from the article]

Published
2023
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20. SINGLE‐CELL RNA‐SEQ OF CLASSIC HAIRY CELL LEUKEMIA REVEALS DISEASE DRIVERS LINKED TO INTRINSIC TREATMENT RESISTANCE AND IDENTIFIES DUSP1 AS POTENTIAL NEW THERAPEUTIC TARGET.

Author

Bohn, J., Salcher, S., Sturm, G., Kugler, V., Feichtner, A., Fritz, A., Torres‐Quesada, O., Mair, A., Scheiber, A., Jäger, U., Brunner, A., Pircher, A., Sopper, S., Stefan, E., Trajanoski, Z., and Wolf, D.

Subjects
RNA sequencing, LEUKEMIA, COMPUTATIONAL biology, SYSTEMS biology
Abstract

B Results: b scRNA-Seq revealed distinct HCL cell clusters characterized by marked overexpression of DUSP1, FOS and JUND in all six patients that were outgrowing at first and second relapse in all three SR. B Introduction: b Standard treatment with purine analogs such as cladribine (2-CdA) achieves excellent remissions in classic hairy cell leukemia (HCL), but up to 25% of patients relapse early and there is a non-diminishing risk of late relapse in complete responders. SINGLE-CELL RNA-SEQ OF CLASSIC HAIRY CELL LEUKEMIA REVEALS DISEASE DRIVERS LINKED TO INTRINSIC TREATMENT RESISTANCE AND IDENTIFIES DUSP1 AS POTENTIAL NEW THERAPEUTIC TARGET. [Extracted from the article]

Published
2023
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22. Radio-Frequency Manipulation of Fano-Feshbach Resonances in an Ultracold Fermi Gas of $^{40}$K

Author

Huang, Lianghui, Wang, Pengjun, Ruzic, B. P., Fu, Zhengkun, Meng, Zengming, Peng, Peng, Bohn, J. L., and Zhang, Jing

Subjects
Condensed Matter::Quantum Gases, Quantum Gases (cond-mat.quant-gas), Condensed Matter::Other, FOS: Physical sciences, Condensed Matter - Quantum Gases
Abstract

Experimental control of magnetic Fano-Feshbach resonances in ultracold $^{40}$K Fermi gases, using radio-frequency (RF) fields, is demonstrated. Spectroscopic measurements are made of three molecular levels within 50 MHz of the atomic continuum, along with their variation with magnetic field. Modifying the scattering properties by an RF field is shown by measuring the loss profile versus magnetic field. This work provides the high accuracy locations of ground molecular states near the s-wave Fano-Feshbach resonance, which can be used to study the crossover regime from a Bose-Einstein condensate to a Bardeen-Cooper-Schrieffer superfluid in presence of an RF field., 5 pages, 3 figures

Published
2014

23. Quenching to unitarity: Quantum dynamics in a 3D Bose gas

Author

Sykes, A. G., Corson, J. P., D'Incao, J. P., Koller, A. P., Greene, C. H., Rey, A. M., Hazzard, K. R. A., and Bohn, J. L.

Subjects
Condensed Matter::Quantum Gases, Quantum Gases (cond-mat.quant-gas), FOS: Physical sciences, Condensed Matter - Quantum Gases
Abstract

We study the dynamics of a dilute Bose gas at zero temperature following a sudden quench of the scattering length from a noninteracting Bose condensate to unitarity (infinite scattering length). We apply three complementary approaches to understand the momentum distribution and loss rates. First, using a time-dependent variational ansatz for the many-body state, we calculate the dynamics of the momentum distribution. Second, we demonstrate that, at short times and large momenta compared to those set by the density, the physics can be well understood within a simple, analytic two-body model. We derive a quantitative prediction for the evolution of Tan's contact, which increases linearly at short times. We also study the three-body losses at finite densities. Consistent with experiments, we observe lifetimes which are long compared to the dynamics of large momentum modes., 4 pages, 3 figures

Published
2013

25. Abstracts of papers presented at the 50th Anniversary Meeting of The Potato Association of America and 13th National Potato Utilization Conference Perkins Inn, Riverhead, New York July 15, 16, 17, 18, 1963

Author

Boyd Glenn D., Peter, Calderon, Smith, Ora, Mattick, L. R., Campbell John C., Cetas R. C., Davis Carl O., Ora Smith, Dearborn C. H., Drazga F. H., Eskew, R. K., Talley, F. B., Eastman Paul J., Ewing E. E., Bohn, J. C., Layer, J. W., Fisher Kenneth D., Franklin Everett W., Lougheed, Everett C., Frost O. M., Goven M. J., Murphy, H. J., Gumbmann M. R., Burr, H. K., Hart Thomas G., Arthur, Hawkins, Anthony, Hepton, Ide L. E., Robert, Kunkel, Kunkel R., Dow, Irving A., James, David W., Lauro, Lujan, Miller Julian C., Fontenot, James F., Young, W. A., Hugh, Murphy, Neufeld C. H. H., Plaisted R. L., Peterson, L. C., Rich Avery E., Sparks Walter C., Stevenson F. J., Akeley, R. V., Cunningham, C. E., William, Thorne, Sawyer, R. L., Wurster R. T., and Young Donald A.

Published
1963
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28. Quantum-State Controlled Chemical Reactions of Ultracold KRb Molecules

Author

Ospelkaus, S., Ni, K. -K., Wang, D., de Miranda, M. H. G., Neyenhuis, B., Qu��m��ner, G., Julienne, P. S., Bohn, J. L., Jin, D. S., and Ye, J.

Subjects
Atomic Physics (physics.atom-ph), Quantum Gases (cond-mat.quant-gas), FOS: Physical sciences, Condensed Matter - Quantum Gases, Physics - Atomic Physics
Abstract

How does a chemical reaction proceed at ultralow temperatures? Can simple quantum mechanical rules such as quantum statistics, single scattering partial waves, and quantum threshold laws provide a clear understanding for the molecular reactivity under a vanishing collision energy? Starting with an optically trapped near quantum degenerate gas of polar $^{40}$K$^{87}$Rb molecules prepared in their absolute ground state, we report experimental evidence for exothermic atom-exchange chemical reactions. When these fermionic molecules are prepared in a single quantum state at a temperature of a few hundreds of nanoKelvins, we observe p-wave-dominated quantum threshold collisions arising from tunneling through an angular momentum barrier followed by a near-unity probability short-range chemical reaction. When these molecules are prepared in two different internal states or when molecules and atoms are brought together, the reaction rates are enhanced by a factor of 10 to 100 due to s-wave scattering, which does not have a centrifugal barrier. The measured rates agree with predicted universal loss rates related to the two-body van der Waals length.

Published
2009

31. Observation of p-wave Threshold Law Using Evaporatively Cooled Fermionic Atoms

Author

DeMarco, B., Bohn, J. L., Burke, J. P., Holland, M., and Jin, D. S.

Subjects
Condensed Matter::Quantum Gases, Condensed Matter (cond-mat), FOS: Physical sciences, Condensed Matter
Abstract

We have measured independently both s-wave and p-wave cross-dimensional thermalization rates for ultracold potassium-40 atoms held in a magnetic trap. These measurements reveal that this fermionic isotope has a large positive s-wave triplet scattering length in addition to a low temperature p-wave shape resonance. We have observed directly the p-wave threshold law which, combined with the Fermi statistics, dramatically suppresses elastic collision rates at low temperatures. In addition, we present initial evaporative cooling results that make possible these collision measurements and are a precursor to achieving quantum degeneracy in this neutral, low-density Fermi system., 5 pages, 3 figures, 1 table

Published
1998

32. Demographic and mortality analysis of hospitalized children at a referral hospital in Addis Ababa, Ethiopia.

Author

Bohn, J. A., Kassaye, B. M., Record, D., Chou, B. C., Kraft, I. L., Purdy, J. C., Hilton, K. A., Miller, D. A., Getachew, S., Addissie, A., and Robison, J. A.

Subjects
CHILD mortality statistics, HOSPITAL care of children, PEDIATRIC emergency services, HOSPITAL admission & discharge, CHI-squared test
Abstract

Background: Global childhood mortality rates remain high. Millennium Development Goal 4 focused efforts on reducing rates by two-thirds between 1990 and 2015. In Ethiopia, child mortality rates dropped 71% from 1990 to 2015, however it is estimated that 184,000 Ethiopian children die each year. There is limited information about pediatric hospital admissions in Ethiopia. Our aims were to examine the temporal relationship of mortality to admission, describe the demographics, and identify cause mortality of children admitted to the Zewditu Memorial Hospital (ZMH). Methods: A four-year retrospective review of pediatric admissions was conducted at the pediatric emergency room and pediatric hospital ward at ZMH in Addis Ababa, Ethiopia. Admission entries from 2011-2014 of children age 29 days-14 years were reviewed. Age, gender, admission date, disease classification, discharge status and date were obtained. Patient gender was compared using Chi-square analysis. A descriptive analysis was used for age and cause mortality. Results: A total of 6866 patient entries were reviewed. The proportion of admissions younger than age 5 was 0.747 (95% CI 0.736-0.757). Overall mortality was 0.042 (95% CI, 0.037-0.047). The proportion of recorded deaths occurring within 2 days of admission was 0.437 (95% CI 0.380-0.494). The proportion of male admissions was significantly higher than female admissions in all age groups (male 0.575, p < 0.0001, 95% CI 0.562-0.586). The main causes of mortality were pneumonia (0.253, 95% CI, 0.203-0.303), severe acute malnutrition (0.222, 95% CI 0.174-0.27), HIV/AIDS-related complications (0.056, 95% CI 0.029-0.083), spina bifida (0.049, 95% CI 0.024-0.074), and hydrocephalus (0.045, 95% CI 0.021-0.069). Conclusions: Our study revealed a lower mortality rate than previously reported in Ethiopia. Despite this, 44% of pediatric hospital mortality occurred early during hospitalization, higher than reported at other Ethiopian hospitals. This adds further evidence that systematic efforts should be dedicated to improve pediatric emergency care. Admissions included 58% male patients, similar to other reports in Ethiopia implying that this may be a nation-wide phenomenon. The observed disparity may be due to societal factors regarding care-seeking behaviors or male predilection for respiratory illness warranting further investigation. Cause mortality patterns were similar to reports in analogous settings. [ABSTRACT FROM AUTHOR]

Published
2016
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33. Development of advanced techniques for rotorcraft state estimation and parameter identification

Author

Hall, W. E., Jr, Bohn, J. G, and Vincent, J. H

Subjects
Aircraft Design, Testing And Performance
Abstract

An integrated methodology for rotorcraft system identification consists of rotorcraft mathematical modeling, three distinct data processing steps, and a technique for designing inputs to improve the identifiability of the data. These elements are as follows: (1) a Kalman filter smoother algorithm which estimates states and sensor errors from error corrupted data. Gust time histories and statistics may also be estimated; (2) a model structure estimation algorithm for isolating a model which adequately explains the data; (3) a maximum likelihood algorithm for estimating the parameters and estimates for the variance of these estimates; and (4) an input design algorithm, based on a maximum likelihood approach, which provides inputs to improve the accuracy of parameter estimates. Each step is discussed with examples to both flight and simulated data cases.

Published
1980

34. Development of longitudinal handling qualities criteria for large advanced supersonic aircraft

Author

Sudderth, R. W, Bohn, J. G, Caniff, M. A, and Bennett, G. R

Subjects
Aircraft Stability And Control
Abstract

Longitudinal handling qualities criteria in terms of airplane response characteristics were developed. The criteria cover high speed cruise maneuvering, landing approach, and stall recovery. Data substantiating the study results are reported.

Published
1975

35. V/STOL lift fan commercial short haul transports: Continuing conceptual design study

Author

Zabinsky, J. M, Minkler, W. F, Bohn, J. G, Derbyshire, T, Middlebrooks, J. E, Mcbarron, J. P, Williams, B, and Miller, C. W

Subjects
Aircraft
Abstract

A design study of commercial V/STOL transport airplanes for a 1985 operational time period has been made. The baseline mission considered was 400 nmi at a cruise speed of M = 0.75 and a 100-passenger payload with VTOL. Variations from the baseline included mission distance, payload, cruise speed, and propulsion system failure philosophy. All designs used propulsion systems consisting of multiple gas generators driving remote tip turbine lift and lift/cruise fans. By considering the fan to be designed for operational reliability, significant simplication of the airplane systems and reduction in airplane size and cost can be achieved.

Published
1974

36. Mariner 4 - A study of the cumulative flux of dust particles over a heliocentric range of 1-1.56 AU 1964-1967

Author

Alexander, W. M and Bohn, J. L

Subjects
Astrophysics
Abstract

Between December 1964 and December 1967, the Mariner 4 dust particle experiment obtained data concerning the distribution of minute zodiacal dust cloud particles over a heliocentric range of 1-1.56 AU. The first measurement was over the complete heliocentric range, while the two additional measurements were made between 1.1 and 1.25 AU in 1966, and between 1.2 and 1.5 AU in 1967. The initial results of these measurements presented the mean cumulative flux for the respective data periods. The results of a detailed study and comparison of the three measurements are presented, with particular emphasis on the variation of the flux as a function of heliocentric range. A small, but statistically significant, increase in the flux is observed between 1.15 and 1.4 AU. The initial reports showed a lower cumulative flux for the latter two measurements. However, a detailed analysis containing corrections for spacecraft attitude indicate that all three measurements yield similar results, and that the particles detected were in low inclination orbits.

Published
1974

37. Simulation and control engineering studies of NASA-Ames 40 foot by 80 foot/80 foot by 120 foot wind tunnels

Author

Bohn, J. G and Jones, J. E

Subjects
Research And Support Facilities (Air)
Abstract

The development and use of a digital computer simulation of the proposed wind tunnel facility is described. The feasibility of automatic control of wind tunnel airspeed and other parameters was examined. Specifications and implementation recommendations for a computer based automatic control and monitoring system are presented.

Published
1978

38. A Technique for Measuring Rotocraft Dynamic Stability in the 40 by 80 Foot Wind Tunnel

Author

Gupta, N. K and Bohn, J. G

Subjects
Communications And Radar
Abstract

An on-line technique is described for the measurement of tilt rotor aircraft dynamic stability in the Ames 40- by 80-Foot Wind Tunnel. The technique is based on advanced system identification methodology and uses the instrumental variables approach. It is particulary applicable to real time estimation problems with limited amounts of noise-contaminated data. Several simulations are used to evaluate the algorithm. Estimated natural frequencies and damping ratios are compared with simulation values. The algorithm is also applied to wind tunnel data in an off-line mode. The results are used to develop preliminary guidelines for effective use of the algorithm.

Published
1977

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