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Diminished neural resources allocation to time processing in Autism Spectrum Disorders
Background: Interval timing, the ability to judge the duration of short events, has been shown to be compromised in Autism Spectrum Disorders (ASD). Timing abilities are ubiquitous and underlie behaviours as varied as sensory integration, motor coordination or communication. It has been suggested that atypical temporal processing in ASD could contribute to some of the disorder's symptoms, in particular motor clumsiness and difficulties in social interaction and communication. Recent behavioural investigations have suggested that interval timing in ASD is characterised by intact sensitivity but reduced precision in duration judgements.
Methods: In this study we investigated the processing of duration as compared to pitch in a group of high-functioning individuals with ASD using magnetoencephalography (MEG). 18 adolescents and adults with ASD and 18 age- and IQ-matched typically-developing control (TDC) individuals compared two consecutive tones according to their duration or pitch in separate experimental blocks. The analysis was carried out exclusively on physically identical stimuli (500 Hz tones lasting 600 ms), which served, according to instruction, as standard or probe in a Duration or Pitch task respectively.
Results: Our results suggest that compared to TDC individuals, individuals with ASD are less able to predict the duration of the standard tone accurately, affecting the sensitivity of the comparison process. In addition, contrary to TDC individuals who allocate resources at different times depending on the nature of the task (pitch or duration discrimination), individuals with ASD seem to engage less resources for the Duration task than for the Pitch task regardless of the context. Although individuals with ASD showed top-down adaptation to the context of the task, this neuronal strategy reflects a bias in the readiness to perform different types of tasks, and in particular a diminished allocation of resources to duration processing which could have cascading effect on learning and development of other cognitiv
Observation of macroscopic Landau-Zener transitions in a superconducting device
A two-level system traversing a level anticrossing has a small probability to
make a so-called Landau-Zener (LZ) transition between its energy bands, in
deviation from simple adiabatic evolution. This effect takes on renewed
relevance due to the observation of quantum coherence in superconducting qubits
(macroscopic "Schrodinger cat" devices). We report an observation of LZ
transitions in an Al three-junction qubit coupled to a Nb resonant tank
circuit.Comment: REVTeX4, 4pp., 4 EPS figures. v2: clarifications added; final, to
appear in EP
Molecular Orbital Tomography using Short Laser Pulses
Recently, a method to image molecular electronic wave functions using high
harmonic generation (HHG) was introduced by Itatani \textit{et al.\} [Nature
{\textbf{432}}, 876 (2004)]. We show that, while the tomographic reconstruction
of general orbitals with arbitrary symmetry cannot be performed with long laser
pulses, this becomes possible when extremely short pulses are used. An
alternative reconstruction equation based on momentum matrix elements, rather
than on dipole matrix elements, is proposed. We present simulations of the
procedure for 2D model systems based on numerical solutions of the
time-dependent Schr\"{o}dinger equation, and present results from further
post-processing of the reconstructed orbitals.Comment: 5 pages, 2 figure
In-situ neutron diffraction during biaxial deformation
A change in strain path may have a significant effect on the mechanical response of metals. In order to understand or even predict the macroscopic behaviour under such conditions a detailed knowledge on the microstructural evolution is crucial. Yet relatively little work has been done to quantify and understand how the inter- and intragranular strains are affected during a change in strain path. In this work we present a new multiaxial deformation rig that allows performing in situ proportional and non-proportional loading under neutron diffraction. We demonstrate the capabilities of this new setup for the case of a 316 L stainless steel. We show that the nature and magnitude of intergranular strain strongly depends on the applied stress state and demonstrate that micro yielding and internal strain recovery are responsible for the observed transient softening during a 90° strain path change. We anticipate that this new characterization method will provide previously inaccessible microstructural data that can serve as input for benchmarking current state-of-the-art crystal plasticity model
Thermal Suppression of Strong Pinning
We study vortex pinning in layered type-II superconductors in the presence of
uncorrelated disorder for decoupled layers. Introducing the new concept of
variable-range thermal smoothing, we describe the interplay between strong
pinning and thermal fluctuations. We discuss the appearance and analyze the
evolution in temperature of two distinct non-linear features in the
current-voltage characteristics. We show how the combination of layering and
electromagnetic interactions leads to a sharp jump in the critical current for
the onset of glassy response as a function of temperature.Comment: LaTeX 2.09, 4 pages, 2 figures, submitted to Phys. Rev. Let
Fv antibodies to aflatoxin B1 derived from a pre-immunized antibody phage display library system
The production and characterization of recombinant antibodies to aflatoxin B[SUB1] (AFB[SUB1]), a potent mycotoxin and carcinogen is described. The antibody fragments produced were then applied for use in a surface plasmon resonance-based biosensor (BIAcore), which measures biomolecular interactions in 'real-time'. Single chain Fv (scFv) antibodies were generated to aflatoxin B1 from an established phage display system, which incorporated a range of different plasmids for efficient scFv expression. The scFv's were used in the development of a competitive ELISA, and also for the development of surface plasmon resonance (SPR)-based inhibition immunoassays. They were found to be suitable for the detection of AFB[SUB1], in this format, with the assays being sensitive and reproducible
Tuning the Charge Density Wave and Superconductivity in CuxTaS2
We report the characterization of layered, 2H-type CuxTaS2, for x between 0
and 0.12. The charge density wave (CDW), at 70 K for TaS2, is destabilized with
Cu doping. The sub-1K superconducting transition in undoped 2H-TaS2 jumps
quickly to 2.5 K at low x, increases to 4.5 K at the optimal composition
Cu0.04TaS2, and then decreases at higher x. The electronic contribution to the
specific heat, first increasing and then decreasing as a function of Cu
content, is 12 mJ mol-1 K-2 at Cu0.04TaS2. Electron diffraction studies show
that the CDW remains present at the optimal superconducting composition, but
with both a changed q vector and decreased coherence length. We present an
electronic phase diagram for the system.Comment: 7 pages, 9 figures. To be published in Physical Review
Optimizing information flow in small genetic networks. II: Feed forward interactions
Central to the functioning of a living cell is its ability to control the
readout or expression of information encoded in the genome. In many cases, a
single transcription factor protein activates or represses the expression of
many genes. As the concentration of the transcription factor varies, the target
genes thus undergo correlated changes, and this redundancy limits the ability
of the cell to transmit information about input signals. We explore how
interactions among the target genes can reduce this redundancy and optimize
information transmission. Our discussion builds on recent work [Tkacik et al,
Phys Rev E 80, 031920 (2009)], and there are connections to much earlier work
on the role of lateral inhibition in enhancing the efficiency of information
transmission in neural circuits; for simplicity we consider here the case where
the interactions have a feed forward structure, with no loops. Even with this
limitation, the networks that optimize information transmission have a
structure reminiscent of the networks found in real biological systems
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