7 results on '"B Deb"'
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2. Above-threshold scattering about a Feshbach resonance for ultracold atoms in an optical collider
- Author
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Milena S. J. Horvath, Ryan Thomas, Eite Tiesinga, Amita B. Deb, and Niels Kjærgaard
- Subjects
Science - Abstract
Studies on energy-dependent scattering of ultracold atoms were previously carried out near zero collision energies. Here, the authors observe a magnetic Feshbach resonance in ultracold Rb collisions for above-threshold energies and their method can also be used to detect higher partial wave resonances.
- Published
- 2017
- Full Text
- View/download PDF
3. Multiple scattering dynamics of fermions at an isolated p-wave resonance
- Author
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R. Thomas, K. O. Roberts, E. Tiesinga, A. C. J. Wade, P. B. Blakie, A. B. Deb, and N. Kjærgaard
- Subjects
Science - Abstract
Multiple scattering with wave-like atoms is known to produce non-trivial many-body effects. Here, the authors investigate multiple scattering in the semi-classical limit using deviations in the scattering halos produced by the collision of indistinguishable ultracold fermions.
- Published
- 2016
- Full Text
- View/download PDF
4. Above-threshold scattering about a Feshbach resonance for ultracold atoms in an optical collider
- Author
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Niels Kjærgaard, Eite Tiesinga, Amita B. Deb, Milena S. J. Horvath, and Ryan Thomas
- Subjects
Atomic Physics (physics.atom-ph) ,Science ,FOS: Physical sciences ,General Physics and Astronomy ,Zero-point energy ,chemistry.chemical_element ,01 natural sciences ,Article ,General Biochemistry, Genetics and Molecular Biology ,Physics - Atomic Physics ,010305 fluids & plasmas ,law.invention ,Rubidium ,Ultracold atom ,law ,0103 physical sciences ,Physics::Atomic Physics ,lcsh:Science ,010306 general physics ,Collider ,Feshbach resonance ,Physics ,Condensed Matter::Quantum Gases ,Multidisciplinary ,Scattering ,Condensed Matter::Other ,Resonance ,General Chemistry ,Magnetic field ,chemistry ,Quantum Gases (cond-mat.quant-gas) ,lcsh:Q ,Atomic physics ,Condensed Matter - Quantum Gases - Abstract
Ultracold atomic gases have realized numerous paradigms of condensed matter physics, where control over interactions has crucially been afforded by tunable Feshbach resonances. So far, the characterization of these Feshbach resonances has almost exclusively relied on experiments in the threshold regime near zero energy. Here, we use a laser-based collider to probe a narrow magnetic Feshbach resonance of rubidium above threshold. By measuring the overall atomic loss from colliding clouds as a function of magnetic field, we track the energy-dependent resonance position. At higher energy, our collider scheme broadens the loss feature, making the identification of the narrow resonance challenging. However, we observe that the collisions give rise to shifts in the center-of-mass positions of outgoing clouds. The shifts cross zero at the resonance and this allows us to accurately determine its location well above threshold. Our inferred resonance positions are in excellent agreement with theory., Studies on energy-dependent scattering of ultracold atoms were previously carried out near zero collision energies. Here, the authors observe a magnetic Feshbach resonance in ultracold Rb collisions for above-threshold energies and their method can also be used to detect higher partial wave resonances.
- Published
- 2017
5. Multiple scattering dynamics of fermions at an isolated p-wave resonance
- Author
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Niels Kjærgaard, Eite Tiesinga, Andrew C. J. Wade, Ryan Thomas, Kris O. Roberts, P. B. Blakie, and Amita B. Deb
- Subjects
Atomic Physics (physics.atom-ph) ,Science ,FOS: Physical sciences ,General Physics and Astronomy ,GASES ,Inelastic scattering ,01 natural sciences ,Resonance (particle physics) ,ULTRACOLD ATOMS ,General Biochemistry, Genetics and Molecular Biology ,Article ,Physics - Atomic Physics ,010305 fluids & plasmas ,symbols.namesake ,Pauli exclusion principle ,0103 physical sciences ,BOSE ,010306 general physics ,Physics ,Elastic scattering ,Condensed Matter::Quantum Gases ,Quantum Physics ,Multidisciplinary ,Phonon scattering ,Scattering ,General Chemistry ,Fermion ,ANDERSON LOCALIZATION ,Quantum Gases (cond-mat.quant-gas) ,symbols ,LASER ,Scattering theory ,Atomic physics ,Condensed Matter - Quantum Gases ,Quantum Physics (quant-ph) ,MATTER - Abstract
The wavefunction for indistinguishable fermions is anti-symmetric under particle exchange, which directly leads to the Pauli exclusion principle, and hence underlies the structure of atoms and the properties of almost all materials. In the dynamics of collisions between two indistinguishable fermions this requirement strictly prohibits scattering into 90 degree angles. Here we experimentally investigate the collisions of ultracold clouds fermionic $\rm^{40}K$ atoms by directly measuring scattering distributions. With increasing collision energy we identify the Wigner threshold for p-wave scattering with its tell-tale dumb-bell shape and no $90^\circ$ yield. Above this threshold effects of multiple scattering become manifest as deviations from the underlying binary p-wave shape, adding particles either isotropically or axially. A shape resonance for $\rm^{40}K$ facilitates the separate observation of these two processes. The isotropically enhanced multiple scattering mode is a generic p-wave threshold phenomenon, while the axially enhanced mode should occur in any colliding particle system with an elastic scattering resonance., Comment: 7 pages, 4 figures, link to supplementary material
- Published
- 2016
- Full Text
- View/download PDF
6. Impact of six-month COVID-19 travel moratorium on Plasmodium falciparum prevalence on Bioko Island, Equatorial Guinea.
- Author
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Hergott DEB, Guerra CA, García GA, Mba Eyono JN, Donfack OT, Iyanga MM, Nguema Avue RM, Abeso Nsegue CN, Ondo Mifumu TA, Rivas MR, Phiri WP, Murphy SC, Guthrie BL, Smith DL, and Balkus JE
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- Humans, Equatorial Guinea epidemiology, Prevalence, Pandemics, Female, Male, Islands, Adult, Betacoronavirus, COVID-19 epidemiology, COVID-19 transmission, Malaria, Falciparum epidemiology, Travel, SARS-CoV-2 isolation & purification, Plasmodium falciparum
- Abstract
Importation of malaria infections is a suspected driver of sustained malaria prevalence on areas of Bioko Island, Equatorial Guinea. Quantifying the impact of imported infections is difficult because of the dynamic nature of the disease and complexity of designing a randomized trial. We leverage a six-month travel moratorium in and out of Bioko Island during the initial COVID-19 pandemic response to evaluate the contribution of imported infections to malaria prevalence on Bioko Island. Using a difference in differences design and data from island wide household surveys conducted before (2019) and after (2020) the travel moratorium, we compare the change in prevalence between areas of low historical travel to those with high historical travel. Here, we report that in the absence of a travel moratorium, the prevalence of infection in high travel areas was expected to be 9% higher than observed, highlighting the importance of control measures that target imported infections., (© 2024. The Author(s).)
- Published
- 2024
- Full Text
- View/download PDF
7. Human mobility patterns and malaria importation on Bioko Island.
- Author
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Guerra CA, Kang SY, Citron DT, Hergott DEB, Perry M, Smith J, Phiri WP, Osá Nfumu JO, Mba Eyono JN, Battle KE, Gibson HS, García GA, and Smith DL
- Subjects
- Communicable Diseases, Imported parasitology, Communicable Diseases, Imported prevention & control, Equatorial Guinea epidemiology, Humans, Islands epidemiology, Malaria, Falciparum parasitology, Malaria, Falciparum prevention & control, Plasmodium falciparum isolation & purification, Prevalence, Risk Factors, Travel trends, Communicable Diseases, Imported epidemiology, Malaria, Falciparum epidemiology, Travel statistics & numerical data, Travel-Related Illness
- Abstract
Malaria burden on Bioko Island has decreased significantly over the past 15 years. The impact of interventions on malaria prevalence, however, has recently stalled. Here, we use data from island-wide, annual malaria indicator surveys to investigate human movement patterns and their relationship to Plasmodium falciparum prevalence. Using geostatistical and mathematical modelling, we find that off-island travel is more prevalent in and around the capital, Malabo. The odds of malaria infection among off-island travelers are significantly higher than the rest of the population. We estimate that malaria importation rates are high enough to explain malaria prevalence in much of Malabo and its surroundings, and that local transmission is highest along the West Coast of the island. Despite uncertainty, these estimates of residual transmission and importation serve as a basis for evaluating progress towards elimination and for efficiently allocating resources as Bioko makes the transition from control to elimination.
- Published
- 2019
- Full Text
- View/download PDF
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