21cm Forest with the SKA

An alternative to both the tomography technique and the power spectrum approach is to search for the 21cm forest, that is the 21cm absorption features against high-z radio loud sources caused by the intervening cold neutral intergalactic medium (IGM) and collapsed structures. Although the existence of high-z radio loud sources has not been confirmed yet, SKA-low would be the instrument of choice to find such sources as they are expected to have spectra steeper than their lower-z counterparts. Since the strongest absorption features arise from small scale structures (few tens of physical kpc, or even lower), the 21cm forest can probe the HI density power spectrum on small scales not amenable to measurements by any other means. Also, it can be a unique probe of the heating process and the thermal history of the early universe, as the signal is strongly dependent on the IGM temperature. Here we show what SKA1-low could do in terms of detecting the 21cm forest in the redshift range z = 7.5-15.Comment: Accepted for publication in the SKA Science Book 'Advancing Astrophysics with the Square Kilometre Array', to appear in 2015; 10 pages, 5 figures; the manuscript is based on Ciardi et al., 2013, MNRAS, 428, 175

The Role of Transverse Occipital Sulcus in Scene Perception and Its Relationship to Object Individuation in Inferior Intraparietal Sulcus

The parietal cortex has been functionally divided into various subregions; however, very little is known about how these areas relate to each other. Two such regions are the transverse occipital sulcus (TOS) scene area and inferior intraparietal sulcus (IPS). TOS exhibits similar activation patterns to the scene selective parahippocampal place area, suggesting its role in scene perception. Inferior IPS, in contrast, has been shown to participate in object individuation and selection via location. Interestingly, both regions have been localized to the same general area of the brain. If these two were actually the same brain region, it would have important implications regarding these regions' role in cognition. To explore this, we first localized TOS and inferior IPS in individual participants and examined the degree of overlap between these regions in each participant. We found that TOS showed only a minor degree of overlap with inferior IPS (∼10%). We then directly explored the role of TOS and inferior IPS in object individuation and scene perception by examining their responses to furnished rooms, empty rooms, isolated furniture, and multiple isolated objects. If TOS and inferior IPS were the same region, we would expect to see similar response patterns in both. Instead, the response of TOS was predominantly scene selective, whereas activity in inferior IPS was primarily driven by the number of objects present in the display, regardless of scene context. These results show that TOS and inferior IPS are nearby but distinct regions, with different functional roles in visual cognition.Psycholog

Enhanced cancer therapy with cold-controlled drug release and photothermal warming enabled by one nanoplatform

Stimuli-responsive nanoparticles hold great promise for drug delivery to improve the safety and efficacy of cancer therapy. One of the most investigated stimuli-responsive strategies is to induce drug release by heating with laser, ultrasound, or electromagnetic field. More recently, cryosurgery (also called cryotherapy and cryoablation), destruction of diseased tissues by first cooling/freezing and then warming back, has been used to treat various diseases including cancer in the clinic. Here we developed a cold-responsive nanoparticle for controlled drug release as a result of the irreversible disassembly of the nanoparticle when cooled to below ∼10 °C. Furthermore, this nanoparticle can be used to generate localized heating under near infrared (NIR) laser irradiation, which can facilitate the warming process after cooling/freezing during cryosurgery. Indeed, the combination of this cold-responsive nanoparticle with ice cooling and NIR laser irradiation can greatly augment cancer destruction both in vitro and in vivo with no evident systemic toxicity

All-Optical Ultrafast Control and Read-Out of a Single Negatively Charged Self-Assembled InAs Quantum Dot

We demonstrate the all-optical ultrafast manipulation and read-out of optical transitions in a single negatively charged self-assembled InAs quantum dot, an important step towards ultrafast control of the resident spin. Experiments performed at zero magnetic field show the excitation and decay of the trion (negatively charged exciton) as well as Rabi oscillations between the electron and trion states. Application of a DC magnetic field perpendicular to the growth axis of the dot enables observation of a complex quantum beat structure produced by independent precession of the ground state electron and the excited state heavy hole spins

Must Do @ VCU

Must Do @ VCU is a set of annual collegial activities that can be performed throughout the year, by faculty, staff and students. These VCU-centered activities are considered to be the things that give VCU its identity. The goal of Must Do @ VCU is to generate a sense of community and of belonging to the University. VCU is a relatively new University and its traditions are therefore not well-established. Must Do @ VCU aims to build on shared experiences as a method to establish VCU culture

Fast spin rotations by optically controlled geometric phases in a quantum dot

We demonstrate optical control of the geometric phase acquired by one of the spin states of an electron confined in a charge-tunable InAs quantum dot via cyclic 2pi excitations of an optical transition in the dot. In the presence of a constant in-plane magnetic field, these optically induced geometric phases result in the effective rotation of the spin about the magnetic field axis and manifest as phase shifts in the spin quantum beat signal generated by two time-delayed circularly polarized optical pulses. The geometric phases generated in this manner more generally perform the role of a spin phase gate, proving potentially useful for quantum information applications.Comment: 4 pages, 3 figures, resubmitted to Physical Review Letter

Extracellular signal-regulated kinase 5 promotes acute cellular and systemic inflammation.

Inflammatory critical illness is a syndrome that is characterized by acute inflammation and organ injury, and it is triggered by infections and noninfectious tissue injury, both of which activate innate immune receptors and pathways. Although reports suggest an anti-inflammatory role for the mitogen-activated protein kinase (MAPK) extracellular signal-regulated kinase 5 (ERK5), we previously found that ERK5 mediates proinflammatory responses in primary human cells in response to stimulation of Toll-like receptor 2 (TLR2). We inhibited the kinase activities and reduced the abundances of ERK5 and MEK5, a MAPK kinase directly upstream of ERK5, in primary human vascular endothelial cells and monocytes, and found that ERK5 promoted inflammation induced by a broad range of microbial TLR agonists and by the proinflammatory cytokines interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α). Furthermore, we found that inhibitors of MEK5 or ERK5 reduced the plasma concentrations of proinflammatory cytokines in mice challenged with TLR ligands or heat-killed Staphylococcus aureus, as well as in mice that underwent sterile lung ischemia-reperfusion injury. Finally, we found that inhibition of ERK5 protected endotoxemic mice from death. Together, our studies support a proinflammatory role for ERK5 in primary human endothelial cells and monocytes, and suggest that ERK5 is a potential therapeutic target in diverse disorders that cause inflammatory critical illness