Emotional modulation of visual cortex activity: A functional nearinfrared spectroscopy study

Functional neuroimaging and electroencephalography reveal emotional effects in early visual cortex. Here, we used fNIRS to examine haemodynamic responses evoked by neutral, positive and negative emotional pictures, matched for brightness, contrast, hue, saturation, spatial frequency and entropy. Emotion content modulated amplitude and latency of oxy-, deoxy- and total haemoglobin response peaks, and induced peripheral autonomic reactions. The processing of positive and negative pictures enhanced haemodynamic response amplitude, and this effect was paralleled by blood pressure changes. The processing of positive pictures was reflected in reduced haemodynamic response peak latency. Together these data suggest early visual cortex holds amplitude-dependent representation of stimulus salience and latency-dependent information regarding stimulus valence, providing new insight into affective interaction with sensory processing

Interlaced Dynamical Decoupling and Coherent Operation of a Singlet-Triplet Qubit

We experimentally demonstrate coherence recovery of singlet-triplet superpositions by interlacing qubit rotations between Carr-Purcell (CP) echo sequences. We then compare performance of Hahn, CP, concatenated dynamical decoupling (CDD) and Uhrig dynamical decoupling (UDD) for singlet recovery. In the present case, where gate noise and drift combined with spatially varying hyperfine coupling contribute significantly to dephasing, and pulses have limited bandwidth, CP and CDD yield comparable results, with T2 ~ 80 microseconds.Comment: related papers at http://marcuslab.harvard.ed

Heterogeneity in susceptibility dictates the order of epidemiological models

The fundamental models of epidemiology describe the progression of an infectious disease through a population using compartmentalized differential equations, but do not incorporate population-level heterogeneity in infection susceptibility. We show that variation strongly influences the rate of infection, while the infection process simultaneously sculpts the susceptibility distribution. These joint dynamics influence the force of infection and are, in turn, influenced by the shape of the initial variability. Intriguingly, we find that certain susceptibility distributions (the exponential and the gamma) are unchanged through the course of the outbreak, and lead naturally to power-law behavior in the force of infection; other distributions often tend towards these "eigen-distributions" through the process of contagion. The power-law behavior fundamentally alters predictions of the long-term infection rate, and suggests that first-order epidemic models that are parameterized in the exponential-like phase may systematically and significantly over-estimate the final severity of the outbreak

Conditional operation of a spin qubit

We report coherent operation of a singlet-triplet qubit controlled by the arrangement of two electrons in an adjacent double quantum dot. The system we investigate consists of two pairs of capacitively coupled double quantum dots fabricated by electrostatic gates on the surface of a GaAs heterostructure. We extract the strength of the capacitive coupling between qubit and double quantum dot and show that the present geometry allows fast conditional gate operation, opening pathways to multi-qubit control and implementation of quantum algorithms with spin qubits.Comment: related papers here: http://marcuslab.harvard.ed

The Resonant Exchange Qubit

We introduce a solid-state qubit in which exchange interactions among confined electrons provide both the static longitudinal field and the oscillatory transverse field, allowing rapid and full qubit control via rf gate-voltage pulses. We demonstrate two-axis control at a detuning sweet-spot, where leakage due to hyperfine coupling is suppressed by the large exchange gap. A {\pi}/2-gate time of 2.5 ns and a coherence time of 19 {\mu}s, using multi-pulse echo, are also demonstrated. Model calculations that include effects of hyperfine noise are in excellent quantitative agreement with experiment

Fast sensing of double-dot charge arrangement and spin state with an rf sensor quantum dot

Single-shot measurement of the charge arrangement and spin state of a double quantum dot are reported, with measurement times down to ~ 100 ns. Sensing uses radio-frequency reflectometry of a proximal quantum dot in the Coulomb blockade regime. The sensor quantum dot is up to 30 times more sensitive than a comparable quantum point contact sensor, and yields three times greater signal to noise in rf single-shot measurements. Numerical modeling is qualitatively consistent with experiment and shows that the improved sensitivity of the sensor quantum dot results from reduced screening and lifetime broadening.Comment: related papers at http://marcuslab.harvard.ed

Diva

My work addresses the aesthetics of flamboyance, glamour, and attitude to express the “camp” sensibilities of the Diva in popular culture. These concepts are explored through the selection of various materials associated with fashion to create sculptural forms that underscore the campy dimension of Diva-ness. Fashion is represented through the use of luscious textures, monochromatic color palettes, and accouterments that merge biomorphic forms with fabric. Fashion plays an influential role in the work through inspiration, material choice, compositions, and aesthetics. Through my practice and research, I have come to view Diva-ness as a subcategory of Camp or as its own category, “Diva Camp.” I have identified four categories in which the relationship between camp and Diva sensibilities run parallel: over-the-top aesthetics, the act of playing the role, self-parody, and gender performativity. The use of a monochromic color scheme and flamboyant fashion materials associated with Diva costuming that are ostentatiously female fit the categories of over-the-top aesthetics and gender performance. The materials used in my work—feather boas and dresses laden with fringe and beads--are campy by their very nature. The forms themselves play a role; they evoke the spirit of Diva-ness through their poses and aesthetics. Self-parody is achieved through the use of the Doric pedestals to support some of the forms. The pedestals are a play on ‘low’ or cheap objects (plant stand) imitating ‘high’ classical Greek architecture. The sculptural pieces are abstract forms that have a human-like presence—each with its own personality, much like pop culture divas themselves. My installations create a sensory experience of Diva campiness through glittery, flamboyant, and mock-glamorous excess

Self-Consistent Measurement and State Tomography of an Exchange-Only Spin Qubit

We report initialization, complete electrical control, and single-shot readout of an exchange-only spin qubit. Full control via the exchange interaction is fast, yielding a demonstrated 75 qubit rotations in under 2 ns. Measurement and state tomography are performed using a maximum-likelihood estimator method, allowing decoherence, leakage out of the qubit state space, and measurement fidelity to be quantified. The methods developed here are generally applicable to systems with state leakage, noisy measurements, and non-orthogonal control axes.Comment: contains Supplementary Informatio

The phase stability of large-size nanoparticle alloy catalysts at ab initio quality using a nearsighted force-training approach

CoPt nanoparticle catalysts are integral to commercial fuel cells. Such systems are prohibitive to fully characterize with electronic structure calculations. Machine-learned potentials offer a scalable solution; however, such potentials are only reliable if representative training data can be employed, which typically requires large electronic structure calculations. Here, we use the nearsighted-force training approach to make high-fidelity machine-learned predictions on large nanoparticles with $>$5,000 atoms using only systematically generated small structures ranging from 38-168 atoms. The resulting ensemble model shows good accuracy and transferability in describing relative energetics for CoPt nanoparticles with various shapes, sizes and Co compositions. It is found that the fcc(100) surface is more likely to form a L1$_0$ ordered structure than the fcc(111) surface. The energy convex hull of the icosahedron shows the most stable particles have Pt-rich skins and Co-rich underlayers. Although the truncated octahedron is the most stable shape across all sizes of Pt nanoparticles, a crossover to icosahedron exists due to a large downshift of surface energy for CoPt nanoparticle alloys. The downshift can be attributed to strain release on the icosahedron surface due to Co alloying. We introduced a simple empirical model to describe the role of Co alloying in the crossover for CoPt nanoparticles. With Monte-Carlo simulations we additionally searched for the most stable atomic arrangement for a truncated octahedron with equal Pt and Co compositions, and also we studied its order-disorder phase transition. We validated the most stable configurations with a new highly scalable density functional theory code called SPARC. Lastly, the order-disorder phase transition for a CoPt nanoparticle exhibits a lower transition temperature and a smoother transition, compared to the bulk CoPt alloy.Comment: 26 pages, 8 figure

Tissue specific membrane association of α1T, a truncated form of the α1 subunit of the Na pump

AbstractWe have assessed the Na pump α-subunit isoform content utilizing site directed antibodies in two vascular smooth muscle (VSM) preparations known to contain functional Na pump sites, VSM microsomal fractions (Na+,K+-ATPase) and intact primary confluent cells (ouabain inhibited 86Rb uptake). A comparison of isoform content was made with kidney microsomes. Both VSM and kidney microsomes contained a full length α1 subunit (~100 kDa) as well as a truncated subunit, α1T (~66 kDa). SDS treatment of VSM microsomes effected an increase in Na+,K+-ATPase and a retention of α1T. SDS treated kidney microsomes retained the α1 isoform and Na+,K+-ATPase. Confluent VSM cells showed no detectable α1T, only α1T. In the absence of detectable full length α1, the α1T protein may represent a functional Na pump component in canine VSM