פרסומים

Dynamical nuclear polarization holds the key for orders of magnitude enhancements of nuclear magnetic resonance signals which, in turn, would enable a wide range of novel applications in biomedical sciences. However, current implementations of DNP require cryogenic temperatures and long times for achieving high polarization. Here we propose and analyze in detail protocols that can achieve rapid hyperpolarization of 13C nuclear spins in randomly oriented ensembles of nanodiamonds at room temperature. Our protocols exploit a combination of optical polarization of electron spins in nitrogen-vacancy centers and the transfer of this polarization to 13C nuclei by means of microwave control to overcome the severe challenges that are posed by the random orientation of the nanodiamonds and their nitrogen-vacancy centers. Specifically, these random orientations result in exceedingly large energy variations of the electron spin levels that render the polarization and coherent control of the nitrogen-vacancy center electron spins as well as the control of their coherent interaction with the surrounding 13C nuclear spins highly inefficient. We address these challenges by a combination of an off-resonant microwave double resonance scheme in conjunction with a realization of the integrated solid effect which, together with adiabatic rotations of external magnetic fields or rotations of nanodiamonds, leads to a protocol that achieves high levels of hyperpolarization of the entire nuclear-spin bath in a randomly oriented ensemble of nanodiamonds even at room temperature. This hyperpolarization together with the long nuclear-spin polarization lifetimes in nanodiamonds and the relatively high density of 13C nuclei has the potential to result in a major signal enhancement in 13C nuclear magnetic resonance imaging and suggests functionalized and hyperpolarized nanodiamonds as a unique probe for molecular imaging both in vitro and in vivo.

Optically detected magnetic resonance using nitrogen-vacancy (NV) colour centres in diamond is a leading modality for nanoscale magnetic field imaging, as it provides single electron spin sensitivity, three-dimensional resolution better than 1 nm (ref. 5) and applicability to a wide range of physical and biological samples under ambient conditions. To date, however, NV-diamond magnetic imaging has been performed using ’real-space’ techniques, which are either limited by optical diffraction to \~250 nm resolution or require slow, point-by-point scanning for nanoscale resolution, for example, using an atomic force microscope, magnetic tip, or super-resolution optical imaging. Here, we introduce an alternative technique of Fourier magnetic imaging using NV-diamond. In analogy with conventional magnetic resonance imaging (MRI), we employ pulsed magnetic field gradients to phase-encode spatial information on NV electronic spins in wavenumber or ’k-space’ followed by a fast Fourier transform to yield real-space images with nanoscale resolution, wide field of view and compressed sensing speed-up.

While business cycles are crucial for determining the dynamics of government budget deficits, it is rare to find an analysis of optimal fiscal rules that are designed to cope with the asymmetric behavior of fiscal variables during the cycle. In this paper I characterize the dynamics of budget deficits along the cycle: i) in recessions marginal propensity to spend is higher than the coefficient of marginal tax revenues, causing an increase of the deficit over GDP; ii) in expansions tax revenues soar allowing for a deficit reduction; however, marginal spending is still high and consequently a full cycle implies an increase in the deficit. Then, I present a model in which fiscal rules are designed to cope with a political bias that is based on two components: the cyclical bias and discretionary tax reductions. According to my analysis, the new generation fiscal rules should be based on a combination of expenditure and revenue rules, which are newer than budget deficit rules and are becoming widespread. According to my empirically calibrated simulation, this combination of rules succeeds on avoiding the political bias and is more cycle-friendly than a budget deficit rule.

Animal models of relapse reveal that the motivation to seek drug is regulated by enduring morphological and physiological changes in the nucleus accumbens, as well as transient synaptic potentiation in the accumbens core (NAcore) that parallels drug-seeking behavior. The current study sought to examine the link between the behavioral and synaptic consequences of cue-induced cocaine seeking by optically silencing glutamatergic afferents to the NAcore from the prelimbic cortex (PL). Adeno-associated virus coding for the inhibitory opsin archaerhodopsin was microinjected into PL, and optical fibers were targeted to NAcore. Animals were trained to self-administer cocaine followed by extinction training, and then underwent cue-induced reinstatement in the presence or absence of 15 min of optically induced inhibition of PL fibers in NAcore. Inhibiting the PL-to-NAcore projection blocked reinstated behavior and was paralleled by decreased dendritic spine head diameter and AMPA/NMDA ratio relative to sham-laser control rats. Interestingly, while spine density was elevated after extinction training, no further effects were observed by cued reinstatement or optical inhibition. These findings validate the critical role for PL afferents to the NAcore in simultaneously regulating both reinstated behavior and the associated transient synaptic potentiation.

9789004291836 Orality and Textuality in the Iranian World: Patterns of Interaction Across the Centuries Edited by Julia Rubanovich BRILL 2015 456 pages $218.00 Hardcover Jerusalem Studies in Religion and Culture; [...]

How does the content of public allegations impact regulatory communication strategies? Employing a multinomial logistic regression analysis and an original data set, this article analyzes the Israeli banking regulator's nuanced responses to public expressions of opinion between 1996 and 2012. We demonstrate this agency's greater propensity to acknowledge problems, yet mostly shift blame to others when faced with claims that regulation is overly lenient, and to deny allegations that regulation is excessive. These findings, although based on one institution, are important because they demonstrate an agency's differential response to external allegations, given their content and its assessment of the relative threat to its reputation. They also suggest that external audiences may be able to shape agency attention and response by carefully framing their claims in light of their understandings of agencies' distinct reputational vulnerabilities.

It is demonstrated that the thermal origin of the excess wing in the THz portion of the dielectric spectrum of water is the same as that of the main dielectric peak. The implication is that models positing the free rotation of water molecules to account for the Excess wing are not correct. A self-terminating Proton cascade is one possible explanation.