The Debt Limit: History and Recent Increases

[Excerpt] The statutory debt limit applies to almost all federal debt. The limit applies to federal debt held by the public (that is, debt held outside the federal government itself) and to federal debt held by the government’s own accounts. Federal trust funds, such as Social Security, Medicare, Transportation, and Civil Service Retirement accounts, hold most of this internally held debt. The government’s surpluses or deficits determine essentially all of the change in debt held by the public. The government’s on-budget fiscal balance, which excludes a U.S. Postal Service net surplus or deficit and a large Social Security surplus of payroll taxes net of paid benefits, does not directly affect debt held in government accounts. Increases or decreases in debt held by government accounts result from net financial flows into accounts holding the debt, such as the Social Security Trust Fund. Legal requirements and government accounting practices also affect levels of debt held by government accounts. On August 2, 2011, President Obama signed into law the Budget Control Act of 2011 (BCA; S.365), after an extended debt limit episode. The federal debt reached its statutory limit on May 16, 2011, prompting Treasury Secretary Timothy Geithner to declare a debt issuance suspension period, allowing certain extraordinary measures to extend Treasury’s borrowing capacity. The BCA included provisions aimed at deficit reduction and would allow the debt limit to rise between $2,100 billion and$2,400 billion in three stages, with the latter two subject to congressional disapproval. Two of the three increases, totaling $900 billion, have occurred, and a request for a third increase is likely to occur in mid-January 2012

Photochemical trajectory modelling studies of the 1987 Antarctic spring vortex

Simulations of Antarctic ozone photochemistry performed using a photochemical model integrated along air parcel trajectories are described. This type of model has a major advantage at high latitudes of being able to simulate correctly the complex interaction between photolysis and temperature fields, which, because of the polar night cannot be represented accurately in a zonally averaged framework. Isentropic air parcel trajectories were computed using Meteorological Office global model analyses and forecast fields from positions along the ER-2 flight paths during the Airborne Antarctic Ozone Experiment in Austral Spring 1987. A photochemical model is integrated along these trajectories using the aircraft observations to initialize constituent concentrations. The model includes additional reactions of the ClO dimer and also bromine reactions, which are thought to play a significant role in Antarctica. The model also includes heterogeneous reactions which are invoked when the air parcel passes through a polar stratospheric cloud (PSC). The existence of a PSC is determined throughout the course of the model integration from the parcel temperature and the saturated vapour pressure of water over an assumed H2O/HNO3 mixture. The air parcel temperature is used to determine the saturated vapor pressure of HNO3 over the same mixture. Mixing ratios which exceed saturation result in condensation of the excess in the model and hence lead to a reduction of the amount of gas phase NO2 available for chemical reaction

Diagnostic studies of the 1987 Antarctic spring vortex

Dynamical fields form the UK Meteorological office global forecast model were used throughout the 1987 Airborne Antarctic Ozone Experiment (AAOE) for flight planning and diagnostic studies. Here, several studies based on the Meteorological Office global analysis (resolution 1.5 degrees lattitude x 1.875 degrees longitude, Lyne et al.) are described. The wind and temperature data derived from the model analysis are compared with observations made from both the DCB and ER-2, and an assessment of the model performance given. Derived quantities such as potential vorticity and model data and discrepancies due to the model data are discussed

Time-resolved measurement of single pulse femtosecond laser-induced periodic surface structure formation

Time-resolved diffraction microscopy technique has been used to observe the formation of laser-induced periodic surface structures (LIPSS) from the interaction of a single femtosecond laser pulse (pump) with a nano-scale groove mechanically formed on a single-crystal Cu substrate. The interaction dynamics (0-1200 ps) was captured by diffracting a time-delayed, frequency-doubled pulse from nascent LIPSS formation induced by the pump with an infinity-conjugate microscopy setup. The LIPSS ripples are observed to form sequentially outward from the groove edge, with the first one forming after 50 ps. A 1-D analytical model of electron heating and surface plasmon polariton (SPP) excitation induced by the interaction of incoming laser pulse with the groove edge qualitatively explains the time-evloution of LIPSS formation.Comment: 4 pages, 5 figure

ANS hard X-ray experiment development program

The hard X-ray (HXX) experiment is one of three experiments included in the Dutch Astronomical Netherlands Satellite, which was launched into orbit on 30 August 1974. The overall objective of the HXX experiment is the detailed study of the emission from known X-ray sources over the energy range 1.5-30keV. The instrument is capable of the following measurements: (1) spectral content over the full energy range with an energy resolution of approximately 20% and time resolution down to 4 seconds; (2) source time variability down to 4 milliseconds; (3) silicon emission lines at 1.86 and 2.00keV; (4) source location to a limit of one arc minute in ecliptic latitude; and (5) spatial structure with angular resolution of the arc minutes. Scientific aspects of experiment, engineering design and implementation of the experiment, and program history are included

Magnetic excitations of spin and orbital moments in cobalt oxide

Magnetic and phonon excitations in the antiferromagnet CoO with an unquenched orbital angular momentum are studied by neutron scattering. Results of energy scans in several Brillouin zones in the (HHL) plane for energy transfers up to 16 THz are presented. The measurements were performed in the antiferromagnetic ordered state at 6 K (well below TN~290 K) as well as in the paramagnetic state at 450 K. Several magnetic excitation modes are identified from the dependence of their intensity on wavevector and temperature. Within a Hund's rule model the excitations correspond to fluctuations of coupled orbital and spin degrees of freedom whose bandwidth is controlled by interionic superexchange. The different ordering domains give rise to several magnetic peaks at each wavevector transfer.Comment: Accepted for publication in Canadian Journal of Physic

Self-referenced characterization of space-time couplings in near single-cycle laser pulses

We report on the characterization of space-time couplings in high energy sub-2-cycle 770nm laser pulses using a self-referencing single-shot method. Using spatially-encoded arrangement filter-based spectral phase interferometry for direct electric field reconstruction (SEA-F-SPIDER) we characterize few-cycle pulses with a wave-front rotation of 2.8x?10^11 rev/sec (1.38 mrad per half-cycle) and pulses with pulse front tilts ranging from to -0.33 fs/um to -3.03 fs/um.Comment: 6 pages, 6 figure

A Reasoned Action Approach Assessment of Instructional Youth Swim Safety Messaging

Youth drowning remains a primary cause of injury and death in the United States, particularly within demographic disparities involving: (a) sex, (b) ethnicity, (c) socioeconomic status, and (d) geographic location. Research has examined knowledge acquisition for injury prevention, but little has been done to understand impact on future behavior. This study examined a learn-to-swim and water safety education program using the Reasoned Action Approach to predict future behavior in/around the water. Youth participants ages 5 to 11 at summer camp programs completed a 55-question survey designed to test 7 competencies through the lens of attitudes, intentions, perceived norms, and self-efficacy. Results indicated that several safety messages are not predicted to produce the desired behavior. These include actions related to concepts such as “rescue” and “calling for help”. Information derived from this study calls for researchers and practitioners to examine water safety programs for efficacy as an injury prevention tool

Recent Extreme Ultraviolet Solar Spectra and Spectroheliograms

Extreme ultraviolet solar spectra and spectroheliogram analyse