Nanoscale Torsional Resonator for Polarization and Spectroscopy of Nuclear Spins

We propose a torsional resonator that couples to the transverse spin dipole of an attached sample. The absence of relative motion eliminates a source of friction that would otherwise hinder nanoscale implementation. Enhanced spontaneous emission induced by the resonator relaxes the longitudinal spin dipole at a rate of ~1  s^(-1) in the low-temperature limit. With signal averaging, single-proton magnetic resonance spectroscopy appears feasible at ~10  mK and a high magnetic field, while single-shot sensitivity is practical for samples with at least tens of protons in a volume of ~5  nm^3

Communication: Partial polarization transfer for single-scan spectroscopy and imaging

A method is presented to partially transfer nuclear spin polarization from one isotope S to another isotope I by the way of heteronuclear spin couplings, while minimizing the loss of spin order to other degrees of freedom. The desired I spin polarization to be detected is a design parameter, while the sequence of pulses at the two Larmor frequencies is optimized to store the greatest unused S spin longitudinal polarization for subsequent use. The unitary evolution for the case of I_NS spin systems illustrates the potentially ideal efficiency of this strategy, which is of particular interest when the spin-lattice relaxation time of S greatly exceeds that of I. Explicit timing and pulses are tabulated for the cases for which M ≤ 10 partial transfers each result in equal final polarization of 1/M or more compared to the final I polarization expected in a single transfer for N = 1, 2, or 3 I spins. Advantages for the ratiometric study of reacting molecules and hyperpolarized initial conditions are outlined

Hyperpolarized ^1H NMR employing low γ nucleus for spin polarization storage

The PASADENA (parahydrogen and synthesis allow dramatically enhanced nuclear alignment)(1, 2) and DNP (Dynamic Nuclear Polarization)(3) methods efficiently hyperpolarize biologically relevant nuclei such as 1^H, (31)^P, (13)^C, (15)^N achieving signal enhancement by a factor of ~ 100000 on currently utilized MRI scanners. Recently, many groups have demonstrated the utility of hyperpolarized MR in biological systems using hyperpolarized (13)^C biomarkers with a relatively long spin lattice relaxation time T_1 on the order of tens of seconds.(4-7) Moreover, hyperpolarized (15)^N for biomedical MR has been proposed due to even longer spin lattice relaxations times.(8) An additional increase of up to tens of minutes in the lifetime of hyperpolarized agent in vivo could be achieved by using the singlet states of low gamma (γ) nuclei.(9) However, as NMR receptivity scales as γ^3 for spin 1/2 nuclei, direct NMR detection of low γ nuclei results in a lower signal-to-noise ratio compared to proton detection. While protons are better nuclei for detection, short spin lattice relaxation times prevent direct 1^H hyperpolarized MR in biomedical applications

Weather Index Insurance and the Pricing of Spatial Basis Risk

Agricultural Finance,

Functional correlates of optic flow motion processing in Parkinson’s disease

The visual input created by the relative motion between an individual and the environment, also called optic flow, influences the sense of self-motion, postural orientation, veering of gait, and visuospatial cognition. An optic flow network comprising visual motion areas V6, V3A, and MT+, as well as visuo-vestibular areas including posterior insula vestibular cortex (PIVC) and cingulate sulcus visual area (CSv), has been described as uniquely selective for parsing egomotion depth cues in humans. Individuals with Parkinson’s disease (PD) have known behavioral deficits in optic flow perception and visuospatial cognition compared to age- and education-matched control adults (MC). The present study used functional magnetic resonance imaging (fMRI) to investigate neural correlates related to impaired optic flow perception in PD. We conducted fMRI on 40 non-demented participants (23 PD and 17 MC) during passive viewing of simulated optic flow motion and random motion. We hypothesized that compared to the MC group, PD participants would show abnormal neural activity in regions comprising this optic flow network. MC participants showed robust activation across all regions in the optic flow network, consistent with studies in young adults, suggesting intact optic flow perception at the neural level in healthy aging. PD participants showed diminished activity compared to MC particularly within visual motion area MT+ and the visuo-vestibular region CSv. Further, activation in visuo-vestibular region CSv was associated with disease severity. These findings suggest that behavioral reports of impaired optic flow perception and visuospatial performance may be a result of impaired neural processing within visual motion and visuo-vestibular regions in PD.Published versio

Dysregulation of visual motion inhibition in major depression

Individuals with depression show depleted concentrations of the inhibitory neurotransmitter GABA in occipital (visual) cortex, predicting weakened inhibition within their visual systems. Yet, visual inhibition in depression remains largely unexplored. To fill this gap, we examined the inhibitory process of centersurround suppression (CSS) of visual motion in depressed individuals. Perceptual performance in discriminating the direction of motion was measured as a function of stimulus presentation time and contrast in depressed individuals (n¼27) and controls (n¼22). CSS was operationalized as the accuracy difference between conditions using large (7.5°) and small (1.5°) grating stimuli. Both depressed and control participants displayed the expected advantage in accuracy for small stimuli at high contrast. A significant interaction emerged between subject group, contrast level and presentation time, indicating that alterations of CSS in depression were modulated by stimulus conditions. At high contrast, depressed individuals showed significantly greater CSS than controls at the 66 ms presentation time (where the effect peaked in both groups). The results' specificity and dependence on stimulus features such as contrast, size and presentation time suggest that they arise from changes in early visual processing, and are not the results of a generalized deficit or cognitive bias.Accepted versio

Effects of Domain-Specific Noise on Visual Motion Processing in Schizophrenia

Background: Visual perception impairments in schizophrenia stem from abnormal information processing. Information processing requires neural response to a stimulus (signal) against a backdrop of 1) random variation in baseline neural activity (internal noise) and sometimes irrelevant environmental stimulation (external noise). Filtering out noise is a critical aspect of information processing, and needs to be critically examined in schizophrenia. Methods: To understand how noise in the visual system constrains perceptual processing, we devised a novel paradigm to build in both signal and external noise on same visual stimulus. Here, instead of uniformed noise, domain-specific noise—variations in stimulus speed—was introduced to evaluate the performance of schizophrenia patients in speed discrimination. Each motion stimulus—a random dot pattern (RDP) comprising 200 moving dots—included a range of speeds, drawn individually from a Gaussian distribution for each dot. The task for patients (n = 26) and controls (n = 28) was to identify which of two stimuli moved faster based on their mean speeds. Findings: Patients exhibited deficient speed discrimination at baseline, in the absence of speed noise. Their speed discrimination was further degraded in the presence of low and medium levels of external noise. In the presence of a high levels of noise, degradation of patients' speed discrimination leveled-off, resulting in similar performance to controls. Conclusion: These domain-specific noise effects on speed discrimination provide direct evidence for the existence of heightened internal noise within a specific visual motion processing domain in schizophrenia

The IKEA effect: When labor leads to love

In four studies in which consumers assembled IKEA boxes, folded origami, and built sets of Legos, we demonstrate and investigate boundary conditions for the IKEA effect—the increase in valuation of self-made products. Participants saw their amateurish creations as similar in value to experts' creations, and expected others to share their opinions. We show that labor leads to love only when labor results in successful completion of tasks; when participants built and then destroyed their creations, or failed to complete them, the IKEA effect dissipated. Finally, we show that labor increases valuation for both “do-it-yourselfers” and novices

Bolstering and Restoring Feelings of Competence via the IKEA Effect

We examine the underlying process behind the IKEA effect, which is defined as consumers' willingness to pay more for self-created products than for identical products made by others, and explore the factors that influence both consumers' willingness to engage in self-creation and the utility that they derive from such activities. We propose that creating products fulfills consumers' psychological need to signal competence to themselves and to others, and that feelings of competence associated with self-created products lead to their increased valuation. We demonstrate that the feelings of competence that arise from assembling products mediate their increased value (Experiment 1), that affirming consumers' sense of self decreases the value they derive from their creations (Experiment 2), and that threatening consumers' sense of self increases their propensity to make things themselves (Experiments 3A and 3B)

Deficient biological motion perception in schizophrenia: results from a motion noise paradigm

Background:: Schizophrenia patients exhibit deficient processing of perceptual and cognitive information. However, it is not well-understood how basic perceptual deficits contribute to higher level cognitive problems in this mental disorder. Perception of biological motion, a motion-based cognitive recognition task, relies on both basic visual motion processing and social cognitive processing, thus providing a useful paradigm to evaluate the potentially hierarchical relationship between these two levels of information processing. Methods: In this study, we designed a biological motion paradigm in which basic visual motion signals were manipulated systematically by incorporating different levels of motion noise. We measured the performances of schizophrenia patients (n = 21) and healthy controls (n = 22) in this biological motion perception task, as well as in coherent motion detection, theory of mind, and a widely used biological motion recognition task. Results: Schizophrenia patients performed the biological motion perception task with significantly lower accuracy than healthy controls when perceptual signals were moderately degraded by noise. A more substantial degradation of perceptual signals, through using additional noise, impaired biological motion perception in both groups. Performance levels on biological motion recognition, coherent motion detection and theory of mind tasks were also reduced in patients. Conclusion: The results from the motion-noise biological motion paradigm indicate that in the presence of visual motion noise, the processing of biological motion information in schizophrenia is deficient. Combined with the results of poor basic visual motion perception (coherent motion task) and biological motion recognition, the association between basic motion signals and biological motion perception suggests a need to incorporate the improvement of visual motion perception in social cognitive remediation