9 research outputs found
Designing For Democracy: Using Design Activism to Re-negotiate the Roles and Rights for Patients
Measurement and simulation of atomic motion in nanoscale optical trapping potentials
Atoms trapped in the evanescent field around a nanofiber experience strong coupling to the light guided in the fiber mode. However, due to the intrinsically strong positional dependence of the coupling, thermal motion of the ensemble limits the use of nanofiber trapped atoms for some quantum tasks. We investigate the thermal dynamics of such an ensemble using short light pulses to make a spatially inhomogeneous population transfer between atomic states. As we monitor the wave packet of atoms created by this scheme, we find a damped oscillatory behavior which we attribute to sloshing and dispersion of the atoms. Oscillation frequencies range around 100 kHz, and motional dephasing between atoms happens on a timescale of 10μs. Comparison to Monte Carlo simulations of an ensemble of 1000 classical particles yields reasonable agreement for simulated ensemble temperatures between 25 and 40μK
Measurement and simulation of atomic motion in nanoscale optical trapping potentials
Atoms trapped in the evanescent field around a nanofiber experience strong
coupling to the light guided in the fiber mode. However, due to the
intrinsically strong positional dependence of the coupling, thermal motion of
the ensemble limits the use of nanofiber trapped atoms for some quantum tasks.
We investigate the thermal dynamics of such an ensemble by using short light
pulses to make a spatially inhomogeneous population transfer between atomic
states. As we monitor the wave packet of atoms created by this scheme, we find
a damped oscillatory behavior which we attribute to sloshing and dispersion of
the atoms. Oscillation frequencies range around 100 kHz, and motional dephasing
between atoms happens on a timescale of 10 s. Comparison to Monte Carlo
simulations of an ensemble of 1000 classical particles yields reasonable
agreement for simulated ensemble temperatures between 25 K and 40 K.Comment: 6 pages, 5 figures. This is a pre-print of an article published in
Applied Physics
Microbial experience through housing in a farmyard-type environment alters intestinal barrier properties in mouse colons
Abstract To close the gap between ultra-hygienic research mouse models and the much more environmentally exposed conditions of humans, we have established a system where laboratory mice are raised under a full set of environmental factors present in a naturalistic, farmyard-type habitat—a process we have called feralization. In previous studies we have shown that feralized (Fer) mice were protected against colorectal cancer when compared to conventionally reared laboratory mice (Lab). However, the protective mechanisms remain to be elucidated. Disruption of the protective intestinal barrier is an acknowledged player in colorectal carcinogenesis, and in the current study we assessed colonic mucosal barrier properties in healthy, feralized C57BL/6JRj male mice. While we found no effect of feralization on mucus layer properties, higher expression of genes encoding the mucus components Fcgbp and Clca1 still suggested mucus enforcement due to feralization. Genes encoding other proteins known to be involved in bacterial defense (Itln1, Ang1, Retnlb) and inflammatory mechanisms (Zbp1, Gsdmc2) were also higher expressed in feralized mice, further suggesting that the Fer mice have an altered intestinal mucosal barrier. These findings demonstrate that microbial experience conferred by housing in a farmyard-type environment alters the intestinal barrier properties in mice possibly leading to a more robust protection against disease. Future studies to unravel regulatory roles of feralization on intestinal barrier should aim to conduct proteomic analyses and in vivo performance of the feralized mice intestinal barrier
Coefficients for Active Transport and Thermogenesis of Ca2+-ATPase Isoforms
Coefficients for active transport of ions and heat in vesicles with Ca2+-ATPase from sarcoplasmic reticulum are defined in terms of a newly proposed thermodynamic theory and calculated using experiments reported in the literature. The coefficients characterize in a quantitative manner different performances of the enzyme isoforms. Four enzyme isoforms are examined, namely from white and red muscle tissue, from blood platelets, and from brown adipose mitochondria. The results indicate that the isoforms have a somewhat specialized function. White muscle tissue and brown adipose tissue have the same active transport coefficient ratio, but the activity level of the enzyme in white muscle is higher than in brown adipose tissue. The thermogenesis ratio is high in both white muscle and brown adipose tissue, in agreement with a specific role in nonshivering thermogenesis. Other isoforms do not have this ability to generate heat. A calcium-dependence of the coefficients is found, which can be understood as being in accordance with the role of this ion as a messenger in muscle contraction as well as in thermogenesis. The investigation points to new experiments related to structure as well as to function of the isoforms
InAs-Al Hybrid Devices Passing the Topological Gap Protocol
We present measurements and simulations of semiconductor-superconductor
heterostructure devices that are consistent with the observation of topological
superconductivity and Majorana zero modes. The devices are fabricated from
high-mobility two-dimensional electron gases in which quasi-one-dimensional
wires are defined by electrostatic gates. These devices enable measurements of
local and non-local transport properties and have been optimized via extensive
simulations for robustness against non-uniformity and disorder. Our main result
is that several devices, fabricated according to the design's engineering
specifications, have passed the topological gap protocol defined in Pikulin
{\it et al.}\ [arXiv:2103.12217]. This protocol is a stringent test composed of
a sequence of three-terminal local and non-local transport measurements
performed while varying the magnetic field, semiconductor electron density, and
junction transparencies. Passing the protocol indicates a high probability of
detection of a topological phase hosting Majorana zero modes. Our experimental
results are consistent with a quantum phase transition into a topological
superconducting phase that extends over several hundred millitesla in magnetic
field and several millivolts in gate voltage, corresponding to approximately
one hundred micro-electron-volts in Zeeman energy and chemical potential in the
semiconducting wire. These regions feature a closing and re-opening of the bulk
gap, with simultaneous zero-bias conductance peaks at {\it both} ends of the
devices that withstand changes in the junction transparencies. The measured
maximum topological gaps in our devices are 20-eV. This demonstration
is a prerequisite for experiments involving fusion and braiding of Majorana
zero modes.Comment: Fixed typos. Fig. 3 is now readable by Adobe Reade