From Blood Oxygenation Level Dependent (BOLD) signals to brain temperature maps

A theoretical framework is presented for converting Blood Oxygenation Level Dependent (BOLD) images to temperature maps, based on the idea that disproportional local changes in cerebral blood flow (CBF) as compared with cerebral metabolic rate of oxygen consumption (CMRO2) during functional brain activity, lead to both brain temperature changes and the BOLD effect. Using an oxygen limitation model and a BOLD signal model we obtain a transcendental equation relating CBF and CMRO2 changes with the corresponding BOLD signal, which is solved in terms of the Lambert W function. Inserting this result in the dynamic bio-heat equation describing the rate of temperature changes in the brain, we obtain a non autonomous ordinary differential equation that depends on the BOLD response, which is solved numerically for each brain voxel. In order to test the method, temperature maps obtained from a real BOLD dataset are calculated showing temperature variations in the range: (-0.15, 0.1) which is consistent with experimental results. The method could find potential clinical uses as it is an improvement over conventional methods which require invasive probes and can record only few locations simultaneously. Interestingly, the statistical analysis revealed that significant temperature variations are more localized than BOLD activations. This seems to exclude the use of temperature maps for mapping neuronal activity as areas where it is well known that electrical activity occurs (such as V5 bilaterally) are not activated in the obtained maps. But it also opens questions about the nature of the information processing and the underlying vascular network in visual areas that give rise to this result

Sex Differences in Attributions to Positive and Negative Sexual Scenarios in Men and Women With and Without Sexual Problems: Reconsidering Stereotypes

People with sexual problems are more likely to attribute negative sexual experiences to themselves, in contrast to sexually functional individuals who attribute negative sexual experiences to external factors such as the circumstance or partner. We investigated attribution patterns in 820 men and 753 women, some of whom reported an orgasmic problem, to assess differences between the sexes and those with and without an orgasmic difficulty. Specifically, using an Internet-based approach, we compared attribution responses to four sexual scenarios, one representing a positive sexual experience and three representing negative sexual experiences. Women were more likely to attribute positive outcomes to their partner than men. Women were also more likely to attribute negative outcomes to themselves than men, but they more readily blamed their partner and circumstances for negative outcomes than men as well. Those with orgasmic problems were less willing to take credit for positive outcomes and more willing to accept blame for negative outcomes. Interaction effects between sex and orgasmic problems further highlighted differences between men’s and women’s attribution patterns. These results are interpreted in the context of traditional notions that men’s attributions tend to be more self-serving and women’s attributions more self-derogatory

Observation of the Quantum Zeno and Anti-Zeno effects in an unstable system

We report the first observation of the Quantum Zeno and Anti-Zeno effects in an unstable system. Cold sodium atoms are trapped in a far-detuned standing wave of light that is accelerated for a controlled duration. For a large acceleration the atoms can escape the trapping potential via tunneling. Initially the number of trapped atoms shows strong non-exponential decay features, evolving into the characteristic exponential decay behavior. We repeatedly measure the number of atoms remaining trapped during the initial period of non-exponential decay. Depending on the frequency of measurements we observe a decay that is suppressed or enhanced as compared to the unperturbed system.Comment: 4 pages, 5 figures, submitted to PR

An Energy-conscious Transport Protocol for Multi-hop Wireless Networks

We present a transport protocol whose goal is to reduce power consumption without compromising delivery requirements of applications. To meet its goal of energy efficiency, our transport protocol (1) contains mechanisms to balance end-to-end vs. local retransmissions; (2) minimizes acknowledgment traffic using receiver regulated rate-based flow control combined with selected acknowledgements and in-network caching of packets; and (3) aggressively seeks to avoid any congestion-based packet loss. Within a recently developed ultra low-power multi-hop wireless network system, extensive simulations and experimental results demonstrate that our transport protocol meets its goal of preserving the energy efficiency of the underlying network.Defense Advanced Research Projects Agency (NBCHC050053