Detection of Vacuum Birefringence with Intense Laser Pulses

We propose a novel technique that promises hope of being the first to directly detect a polarization in the quantum electrodynamic (QED) vacuum. The technique is based upon the use of ultra-short pulses of light circulating in low dispersion optical resonators. We show that the technique circumvents the need for large scale liquid helium cooled magnets, and more importantly avoids the experimental pitfalls that plague existing experiments that make use of these magnets. Likely improvements in the performance of optics and lasers would result in the ability to observe vacuum polarization in an experiment of only a few hours duration.Comment: 4 pages, 1 figur

British Revival and American Decline? Anglo-American Relations and the Persian Gulf 1979–1987

Understanding the trajectory of Anglo-American relations in the Middle East in the latter half of the twentieth century has rarely enjoyed consensus. Some have characterised it as a period of perpetual competition, with London unwilling or unable to accept its diminished status. Others, post-Suez, are more sanguine. Britain, it is argued, acted as a tutor to the United States still struggling to configure its global power with its regional interests. This article questions such assumptions. While its overt military presence across the Persian Gulf had declined by the mid-1970s, Britain had kept discreet military ties with a range of actors in the Gulf. By the early 1980s, with Washington struggling to make sense of the Iranian revolution and its wider impact across the region, Britain, now under Margaret Thatcher, proved adept at using commercial opportunities to recast and secure its strategic and economic interests across the Gulf, notably in Saudi Arabia. Thus, far from being the nadir of British influence in the Persian Gulf, the 1980s witnessed its revival

Optimization of Exercise Countermeasures for Human Space Flight: Operational Considerations for Concurrent Strength and Aerobic Training

The physiological challenges presented by space flight and in microgravity (μG) environments are well documented. μG environments can result in declines muscle mass, contractile strength, and functional capabilities. Previous work has focused on exercise countermeasures designed to attenuate the negative effects of μG on skeletal muscle structure, function, and contractile strength and aerobic fitness parameters. Exposure to μG environments influences both strength and aerobic type physical qualities. As such, the current exercise recommendations for those experiencing μG involve a combination of strength and aerobic training or “concurrent training.” Concurrent training strategies can result in development and maintenance of both strength and aerobic capabilities. However, terrestrial research has indicated that if concurrent training strategies are implemented inappropriately, strength development can be inhibited. Previous work has also demonstrated that the aforementioned inhibition of strength development is dependent on the frequency of aerobic training, modality of aerobic training, the relief period between strength and aerobic training, and the intra-session sequencing of strength and aerobic training. While time constraints and feasibility are important considerations for exercise strategies in μG, certain considerations could be made when prescribing concurrent strength and aerobic training to those experiencing human space flight. If strength and aerobic exercise must be performed in close proximity, strength should precede aerobic stimulus. Eccentric strength training methods should be considered to increase mechanical load and reduce metabolic cost. For aerobic capacity, maintenance cycle and/or rowing-based high-intensity intermittent training (HIIT) should be considered and cycle ergometry and/or rowing may be preferable to treadmill running

Community Guide to Agriculture (Johnson County)

More than 1,000 people have been reached though the various Johnson County Guide to Agriculture programs. Among the outreach efforts were workshops, displays, farm and farm business tours, and programs on Iowa City\u27s public cable channel

Decisions about the use of psychotropic medication during pregnancy: a qualitative study

OBJECTIVE: To understand the perspectives of women with severe mental illness concerning the use of psychotropic medicines while pregnant. DESIGN: Interviews conducted by female peer researchers with personal experience of making or considering decisions about using psychotropic medicines in pregnancy, supported by professional researchers. PARTICIPANTS: 12 women who had had a baby in the past 5 years and had taken antipsychotics or mood-stabilisers for severe mental illness within the 12-month period immediately prior to that pregnancy. Recruitment to the study was via peer networks and the women interviewed came from different regions of England. SETTING: Interviews were arranged in places where women felt comfortable and that accommodated their childcare needs including their home, local library and the research office. RESULTS: The views expressed demonstrated complex attempts to engage with decision-making about the use of psychotropic medicines in pregnancy. In nearly all cases, the women expressed the view that healthcare professionals had access to limited information leaving women to rely on experiential and common sense evidence when making decisions about medicine taking during pregnancy. CONCLUSIONS: The findings complement existing work using electronic health records by providing explanations for the discontinuation of psychotropic medicines in pregnancy. Further work is necessary to understand health professionals’ perspectives on the provision of services and care to women with severe mental illness during pregnancy

Tidally stripped halo stars from the Large Magellanic Cloud in the Galactic North

We examine whether the Large Magellanic Cloud (LMC) is currently losing its stellar halo to Milky Way (MW) tides. We present a live $N$-body model for the ongoing MW-LMC interaction that predicts a prominent stream of stars tidally stripped from the progenitor LMC. We use this model to define a strategy to search for stripped material in kinematic space. Of the available stellar tracers, we conclude that samples of RR Lyrae stars provide the highest density of kinematic tracers at present. Using a sample of RR Lyrae stars with Gaia EDR3 astrometry we show that the LMC stellar halo in the Southern Galactic hemisphere extends at least out to $\sim 30^\circ$ from the galaxy centre. In addition, several leading arm candidates are found in the Northern hemisphere as far above the disc plane as $b=+34^\circ$ (at 68$^\circ$ from the LMC).Comment: Submitted to MNRAS; this version features minor updates. Comments welcom

Development of a protocol for maintaining viability while shipping organoid-derived retinal tissue.

Retinal organoid technology enables generation of an inexhaustible supply of three-dimensional retinal tissue from human pluripotent stem cells (hPSCs) for regenerative medicine applications. The high similarity of organoid-derived retinal tissue and transplantable human fetal retina provides an opportunity for evaluating and modeling retinal tissue replacement strategies in relevant animal models in the effort to develop a functional retinal patch to restore vision in patients with profound blindness caused by retinal degeneration. Because of the complexity of this very promising approach requiring specialized stem cell and grafting techniques, the tasks of retinal tissue derivation and transplantation are frequently split between geographically distant teams. Delivery of delicate and perishable neural tissue such as retina to the surgical sites requires a reliable shipping protocol and also controlled temperature conditions with damage-reporting mechanisms in place to prevent transplantation of tissue damaged in transit into expensive animal models. We have developed a robust overnight tissue shipping protocol providing reliable temperature control, live monitoring of the shipment conditions and physical location of the package, and damage reporting at the time of delivery. This allows for shipping of viable (transplantation-competent) hPSC-derived retinal tissue over large distances, thus enabling stem cell and surgical teams from different parts of the country to work together and maximize successful engraftment of organoid-derived retinal tissue. Although this protocol was developed for preclinical in vivo studies in animal models, it is potentially translatable for clinical transplantation in the future and will contribute to developing clinical protocols for restoring vision in patients with retinal degeneration

Ginzburg-Landau Theory of Josephson Field Effect Transistors

A theoretical model of high-T_c Josephson Field Effect Transistors (JoFETs) based on a Ginzburg-Landau free energy expression whose parameters are field- and spatially- dependent is developed. This model is used to explain experimental data on JoFETs made by the hole-overdoped Ca-SBCO bicrystal junctions (three terminal devices). The measurements showed a large modulation of the critical current as a function of the applied voltage due to charge modulation in the bicrystal junction. The experimental data agree with the solutions of the theoretical model. This provides an explanation of the large field effect, based on the strong suppresion of the carrier density near the grain boundary junction in the absence of applied field and the subsequent modulation of the density by the field.Comment: REVTEX, 4 figures upon request, submitted to Appl. Phys. Let

IL-2 limits IL-12 enhanced lymphocyte proliferation during \u3ci\u3eLeishmania amazonensis\u3c/i\u3e infection

C3H mice infected with Leishmania amazonensis develop persistent, localized lesions with high parasite loads. During infection, memory/effector CD44hiCD4+ T cells proliferate and produce IL-2, but do not polarize to a known effector phenotype. Previous studies have demonstrated IL-12 is insufficient to skew these antigen-responsive T cells to a functional Th1 response. To determine the mechanism of this IL-12 unresponsiveness, we used an in vitro assay of repeated antigen activation. Memory/effector CD44hiCD4+ T cells did not increase proliferation in response to either IL-2 or IL-12, although these cytokines upregulated CD25 expression. Neutralization of IL-2 enhanced CD4+ T cell proliferation in response to IL-12. This cross-regulation of IL-12 responsiveness by IL-2 was confirmed in vivo by treatment with anti-IL-2 antibodies and IL-12 during antigen challenge of previously infected mice. These results suggest that during chronic infection with L. amazonensis, IL-2 plays a dominant, immunosuppressive role independent of identifiable conventional Treg cells