30 research outputs found
Adiabatic population transfer via multiple intermediate states
This paper discusses a generalization of stimulated Raman adiabatic passage
(STIRAP) in which the single intermediate state is replaced by intermediate
states. Each of these states is connected to the initial state \state{i} with
a coupling proportional to the pump pulse and to the final state \state{f}
with a coupling proportional to the Stokes pulse, thus forming a parallel
multi- system. It is shown that the dark (trapped) state exists only
when the ratio between each pump coupling and the respective Stokes coupling is
the same for all intermediate states. We derive the conditions for existence of
a more general adiabatic-transfer state which includes transient contributions
from the intermediate states but still transfers the population from state
\state{i} to state \state{f} in the adiabatic limit. We present various
numerical examples for success and failure of multi- STIRAP which
illustrate the analytic predictions. Our results suggest that in the general
case of arbitrary couplings, it is most appropriate to tune the pump and Stokes
lasers either just below or just above all intermediate states.Comment: 14 pages, two-column revtex style, 10 figure
Microstructured thin-film electrode technology enables proof of concept of scalable, soft auditory brainstem implants
Auditory brainstem implants (ABIs) provide sound awareness to deaf individuals who are not candidates for the cochlear implant. The ABI electrode array rests on the surface of the cochlear nucleus (CN) in the brainstem and delivers multichannel electrical stimulation. The complex anatomy and physiology of the CN, together with poor spatial selectivity of electrical stimulation and inherent stiffness of contemporary multichannel arrays, leads to only modest auditory outcomes among ABI users. Here, we hypothesized that a soft ABI could enhance biomechanical compatibility with the curved CN surface. We developed implantable ABIs that are compatible with surgical handling, conform to the curvature of the CN after placement, and deliver efficient electrical stimulation. The soft ABI array design relies on precise microstructuring of plastic-metal-plastic multilayers to enable mechanical compliance, patterning, and electrical function. We fabricated soft ABIs to the scale of mouse and human CN and validated them in vitro. Experiments in mice demonstrated that these implants reliably evoked auditory neural activity over 1 month in vivo. Evaluation in human cadaveric models confirmed compatibility after insertion using an endoscopic-assisted craniotomy surgery, ease of array positioning, and robustness and reliability of the soft electrodes. This neurotechnology offers an opportunity to treat deafness in patients who are not candidates for the cochlear implant, and the design and manufacturing principles are broadly applicable to implantable soft bioelectronics throughout the central and peripheral nervous system
Safety and Success of Repeat Lung Needle Biopsies in Patients with Epidermal Growth Factor ReceptorâMutant Lung Cancer
Evolution of Body Composition Following Autologous and Allogeneic Hematopoietic Cell Transplantation: Incidence of Sarcopenia and Association with Clinical Outcomes
Civil Rights Roll-Call Voting in the House of Representatives, 1957-1991: A Systematic Analysis
Citizens, Knowledge, and the Information Environment
In a democracy, knowledge is power. Research explaining the determinants of knowledge focuses on unchanging demographic and socioeconomic characteristics. This study combines data on the publicâs knowledge of nearly 50 political issues with media coverage of those topics. In a two-part analysis, we demonstrate how education, the strongest and most consistent predictor of political knowledge, has a more nuanced connection to learning than is commonly recognized. Sometimes education is positively related to knowledge. In other instances its effect is negligible. A substantial part of the variation in the education-knowledge relationship is due to the amount of information available in the mass media. This study is among the first to distinguish the short-term, aggregate-level influences on political knowledge from the largely static individual-level predictors and to empirically demonstrate the importance of the information environment