Hard gamma ray emission from blazars

The gamma-ray emission expected from compact extragalactic sources of nonthermal radiation is examined. The highly variable objects in this class should produce copious amounts of self-Compton gamma-rays in the compact relativistic jet. This is shown to be a likely interpretation of the hard gamma-ray emission recently detected from the quasar 3C 279 during a period of strong nonthermal flaring at lower frequencies. Ways of discriminating between the self-Compton model and other possible gamma-ray emission mechanisms are discussed

Expected level of self-Compton scattering in radio loud quasars

Radio-loud quasars usually contain parsec-scale nonthermal jets. The most compact emission region ('the core'), and perhaps some of the moving 'knots', are expected to be efficient producers of inverse Compton scattered X-rays and gamma-rays since many of the synchrotron photons will upscatter before escaping. Through multifrequency flux density observations and Very Long Baseline Interferometry (VLBI) measurements of angular sizes, one can predict the flux density of this self-Compton high-energy emission. It is not always the case that the brightest synchrotron sources are also the brightest X-ray and gamma-ray sources. Perhaps a better predictor of high-energy brightness is the ratio of hard X-ray to high-frequency radio emission. Using the synchrotron self-Compton relations, we predict the gamma-ray fluxes of several sources we expect to be detected by the Energetic Gamma Ray Experiment Telescope (EGRET). More accurate predictions will be made when we complete a program of contemporaneous radio-submillimeter and X-ray observations during the course of the EGRET all-sky survey

Policy uncertainty: a new indicator

The damaging impact of economic uncertainty on growth has been reasonably well studied - but what happens when there is uncertainty about economic policy-making? Nicholas Bloom and colleagues have developed a measure of this distinct kind of uncertainty, one that shows the value of restoring stability to current policy actions.US economic policy, global financial markets,

Peptide Carbocycles: From −SS– to −CC– via a Late-Stage “Snip-and-Stitch”

One way to improve the therapeutic potential of peptides is through cyclization. This is commonly done using a disulfide bond between two cysteine residues in the peptide. However, disulfide bonds are susceptible to reductive cleavage, and this can deactivate the peptide and endanger endogenous proteins through covalent modification. Substituting disulfide bonds with more chemically robust carbon-based linkers has proven to be an effective strategy to better develop cyclic peptides as drugs, but finding the optimal carbon replacement is synthetically laborious. We report a new late-stage platform wherein a single disulfide bond in a cyclic peptide can serve as the progenitor for any number of new carbon-rich groups, derived from organodiiodides, using a Zn:Cu couple and a hydrosilane. We show that this platform can furnish entirely new carbocyclic scaffolds with enhanced permeability and structural integrity and that the stereochemistry of the new cycles can be biased by a judicious choice in silane

RNA’s Thermodynamically Favored Position on Ice

Previous molecular dynamics (MD) work simulated an 8-nucleotide RNA strand on ice, speculatively concluding RNA is stabilized by hydrogen-bonding with the ice’s crystal lattice. That conclusion is investigated by studying a simpler RNA dinucleotide, simulated using GROMACS MD computer simulations. Umbrella sampling results indicate that the most thermodynamically stable position for the RNA to bond is to the uppermost layer of the ice crystal’s basal plane

What Are The Monetary Effects Of Education In The Market For Major League Baseball Players?

In this article, we test the relationship between college attendance and earnings for Major League Baseball players. Using a cross-section of non-pitchers from the 2005 season, we find that schooling does not influence earnings. These results seemingly contradict the schooling-earnings theory and suggest that the market for baseball players may be purely talent-driven

Blindsight: How We See Disabilities in Tort Litigation

Tort litigation operates with a distorted perspective of disability. It suffers from blindsight; it does not see people with disabilities the way they see themselves. Disability advocates emphasize that most people with disabilities lead happy lives. Deeply rooted biases, however, make it difficult for this perspective to be recognized. Tort litigation’s heavy emphasis on medical testimony and its repeated portrayal of plaintiffs as “less than whole” over-emphasize the physical aspects of disability and unfairly depict people with disabilities as tragic. When legal actors embrace these views, they reinforce harmful stereotypes outside the courthouse doors. Newly disabled plaintiffs are also likely to internalize this distorted perspective, as they are repeatedly exposed to it in the course of the litigation. This Article recommends several ways that tort litigation can present plaintiffs with disabilities in more empowering ways, while still recognizing the severity of the injuries involved, and without sacrificing the recovery of hedonic damages or otherwise reducing the plaintiffs’ awards

Higher policy uncertainty curbs business investment and employment growth

The years following the global economic crisis of 2008-2009 have been marked by policy uncertainty, both in the US and across the world. In new research, Scott R. Baker, Nicholas Bloom, and Steven Davis develop an index of economic policy uncertainty to examine how this uncertainty shapes economic outcomes. Using data going back to 1900 and extending coverage to 11 major economies, they find that heightened levels of policy uncertainty leads to firms reducing investment and employment, which in turn contributes to the sluggish growth which many economies have experienced in recent years

Measuring economic policy uncertainty

We develop a new index of economic policy uncertainty (EPU) based on newspaper coverage frequency. Several types of evidence – including human readings of 12,000 newspaper articles – indicate that our index proxies for movements in policy-related economic uncertainty. Our US index spikes near tight presidential elections, Gulf Wars I and II, the 9/11 attacks, the failure of Lehman Brothers, the 2011 debt-ceiling dispute and other major battles over fiscal policy. Using firm-level data, we find that policy uncertainty raises stock price volatility and reduces investment and employment in policy-sensitive sectors like defense, healthcare, and infrastructure construction. At the macro level, policy uncertainty innovations foreshadow declines in investment, output, and employment in the United States and, in a panel VAR setting, for 12 major economies. Extending our US index back to 1900, EPU rose dramatically in the 1930s (from late 1931) and has drifted upwards since the 1960s