1,019 research outputs found
PMH18 SCHIZOPHRENIA MODELING: FACTORS ASSOCIATED WITH THE RISK OF BEING IN A SPECIFIC DISEASE STATE
Proximity DC squids in the long junction limit
We report the design and measurement of
Superconducting/normal/superconducting (SNS) proximity DC squids in the long
junction limit, i.e. superconducting loops interrupted by two normal metal
wires roughly a micrometer long. Thanks to the clean interface between the
metals, at low temperature a large supercurrent flows through the device. The
dc squid-like geometry leads to an almost complete periodic modulation of the
critical current through the device by a magnetic flux, with a flux periodicity
of a flux quantum h/2e through the SNS loop. In addition, we examine the entire
field dependence, notably the low and high field dependence of the maximum
switching current. In contrast with the well-known Fraunhoffer-type
oscillations typical of short wide junctions, we find a monotonous gaussian
extinction of the critical current at high field. As shown in [15], this
monotonous dependence is typical of long and narrow diffusive junctions. We
also find in some cases a puzzling reentrance at low field. In contrast, the
temperature dependence of the critical current is well described by the
proximity effect theory, as found by Dubos {\it et al.} [16] on SNS wires in
the long junction limit. The switching current distributions and hysteretic IV
curves also suggest interesting dynamics of long SNS junctions with an
important role played by the diffusion time across the junction.Comment: 12 pages, 16 figure
Direct measurement of the phase coherence length in a GaAs/GaAlAs square network
The low temperature magnetoconductance of a large array of quantum
coherentloops exhibits Altshuler-Aronov-Spivak oscillations which
periodicitycorresponds to 1/2 flux quantum per loop.We show that the
measurement of the harmonics content in a square networkprovides an accurate
way to determine the electron phase coherence length in units of the
lattice length without any adjustableparameters.We use this method to determine
in a network realised from a 2Delectron gas (2DEG) in a GaAS/GaAlAs
heterojunction. The temperaturedependence follows a power law from
1.3 K to 25 mK with nosaturation, as expected for 1D diffusive electronic
motion andelectron-electron scattering as the main decoherence mechanism.Comment: Additional experimental data in version
Influence of cognitive reserve on neuropsychological functioning in bipolar disorder: Findings from a 5‐year longitudinal study
Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/136365/1/bdi12470_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/136365/2/bdi12470.pd
Equivalent linear change in cognition between individuals with bipolar disorder and healthy controls over 5 years
ObjectivesCognitive dysfunction is a key feature of bipolar disorder (BD). However, not much is known about its temporal stability, as some studies have demonstrated a neurodegenerative model in BD while others have shown no change in cognitive functioning over time. Building upon our prior work, which examined the natural course of executive functioning, the current study aimed to investigate the natural course of memory, emotion processing, and fine motor dexterity over a 5‐year period in BD and healthy control (HC) samples.MethodsUsing a 5‐year longitudinal cohort, 90 individuals with BD and 17 HCs were administered a battery of neuropsychological tests at study baseline and at 1 and 5 years after study entry that captured four areas of cognitive performance: visual memory, auditory memory, emotion processing, and fine motor dexterity.ResultsLatent growth curve modeling showed no group differences in the slopes of any of the cognitive factors between the BD and HC groups. Age at baseline was negatively associated with visual memory, emotion processing, and fine motor dexterity. Education level was positively associated with auditory and visual memory and fine motor. Female gender was negatively associated with emotion processing.ConclusionsExtending our prior work on longitudinal evaluation of executive functioning, individuals with BD show similar linear change in other areas of cognitive functioning including memory, emotion processing, and fine motor dexterity as compared to unaffected HCs. Age, education, and gender may have some differential effects on cognitive changes.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/142144/1/bdi12532.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/142144/2/bdi12532_am.pd
Magnetic field asymmetry of mesocopic dc rectification in Aharonov Bohm rings
Fundamental Casimir-Onsager symmetry rules for linear response do not apply
to non linear transport. This motivates the investigation of nonlinear dc
conductance of mesoscopic GaAs/GaAlAs rings in a 2 wire configuration. The
second order current response to a potential bias is of particular interest. It
is related to the sensitivity of conductance fluctuations to this bias and
contains information on electron interactions not included in the linear
response. In contrast with the linear response which is a symmetric function of
magnetic field we find that this second order response exhibits a field
dependence which contains an antisymmetric part. We analyse the flux periodic
and aperiodic components of this asymmetry and find that they only depend on
the conductance of the rings which is varied by more than an order of
magnitude. These results are in good agreement with recent theoretical
predictions relating this asymmetric response to the electron interactions.Comment: 5 pages, 4 figure
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