819 research outputs found
Foreword
This volume of the San Diego Law Review, devoted to the role of the multinational corporations, is further evidence of the burgeoning literature surrounding the emergence of these corporations in the public consciousness in recent years. Economists, political scientists, sociologists, lawyers, Governors of the Federal Reserve Board, government officials, in both the Executive and legislative branches, are seeking to understand how the activities of these corporations affect national and international economic and financial policies
The Search for a Viable Foreign Economic Policy
United States foreign policy is, to a great degree, influenced by the performance of the international economy. This fact was brought home with dramatic force in 1973, when Arab oil-producing countries suddenly quadrupled the price of oil. That abrupt increase in price, followed by the Arab oil embargo, nearly crippled the economies of the industrial nations of the west. The recent political upheaval in Iran and its affect on the world oil supply is only another poignant example of the extent to which the performance of the American economy, which obviously includes our national and multinational business enterprises, is intimately affected by external economic factors. It is becoming increasingly apparent that, in the global village, politics cannot be separated from economics and business
Ending Emergency Government
MY CONCERN IS TO END emergency government which the United States has practiced since March 9, 1933, and to establish an orderly procedure for handling inevitable emergency situations. This is an issue of importance to our common future and the future well-being of our constitutional system of government
Results of a LMXB survey: variation in the height of the neutron star blackbody emission region
We present results of a survey of the spectra of Low Mass X-ray Binaries
using ASCA. It is shown that all sources in the survey are well-fitted by the
same two-component emission model that we have previously shown is able to
describe both the non-dip and dip spectra of the dipping class of LMXB. This
model consists of point-like blackbody emission from the neutron star plus
Comptonized emission from a disk-like accretion disk corona of radius typically
50,000 km. Additional data from results published elsewhere by us from BeppoSAX
and ASCA are added to the survey. The large variation in blackbody luminosity
of survey sources is shown to be due primarily to major changes in blackbody
emitting area. Fitting a multi-temperature disk blackbody plus Comptonization
model to the survey spectra requires values of inner disk radius substantially
less than the neutron star radius in many cases, making disk origin of the
blackbody highly unlikely. Assuming that the emission is from an equatorial
strip on the neutron star, it is shown that the half-height of the strip h
agrees well with the half-height H of the radiatively-supported inner accretion
disk, this agreement spanning three orders of magnitude in each parameter.
Possible mechanisms for the agreement are discussed, including radial accretion
flow between inner disk and star, and accretion flow ``creep' on the surface of
the neutron star.Comment: 10 pages, 7 ps figures; accepted for publication in A&A Main Journa
Physical changes during Z-track movement in Sco X-1 on the flaring branch
We present results of a detailed study of X-ray flaring in the Z-track source
Sco X-1 in a highly super-Eddington state made using high quality Rossi-XTE
data from the PCA and HEXTE instruments. The emission model successfully used
to explain the dipping LMXB, and other classes of LMXB in recent years, was
applied to study the physical evolution along the Z-track which remains a major
problem. This model consists of blackbody emission from the neutron star plus
Comptonized emission from an extended accretion disk corona. As found in
earlier work, major changes take place in the neutron star blackbody emission
with kT increasing in flaring, and the blackbody radius R_BB increasing
substantially to a maximum value of 9.4 +/- 0.6 km, consistent with the radius
of the neutron star, after which R_BB decreases. Thus this result is a
measurement of neutron star radius. The behaviour of Sco X-1 in flaring is
compared with our previous results for the strong flaring that takes place in
the bright dipping, flaring LMXB X 1624-490. Remarkably, during movement along
the Normal Branch towards the apex with the Flaring Branch, the luminosities of
both spectral components decrease, suggesting the possibility that Mdot may
decrease on the Normal Branch, contrary to the widely-held view that Mdot
increases monotonically along the Z-track. During flaring, we detect for the
first time an increase of the Comptonization cut-off energy which may suggest
heating of the ADC plasma by the neutron star flare. The energy of a broad
Gaussian line at 6.4 keV does not change, but the intensity of the line
increases in flaring suggesting either an increase in ADC size in flaring or
the effects of irradiation by the neutron star.Comment: 12 pages including 8 figures, Astronomy and Astrophysics in press;
reference list correcte
Measurements of accretion disc corona size in LMXB: consequences for Comptonization and LMXB models
We present results of measurements of the radial extent of the accretion disc
corona in low mass X-ray binaries. These results prove conclusively the
extended nature of the ADC, with radial extent varying from 20,000 km in the
faintest sources to 700,000 km in the brightest, a substantial fraction of the
accretion disc radius, typically 15%. This result rules out the Eastern model
for LMXB which is extensively used, in which the Comptonizing region is a small
central region. The ADC size depends strongly on the 1 - 30 keV source
luminosity via a simple relationship r_ADC = L^{0.88 +/- 0.16} (99% confidence)
close to a simple proportionality. We also present limited evidence that the
ADC size agrees with the Compton radius r_C, or maximum radius for hydrostatic
equilibrium. The results are consistent with models in which an extended ADC is
formed by illumination of the disc by the central source. The dependence on
luminosity may reflect the known decrease of coronal temperature as the source
luminosity increases leading to an increase of r_C. The extended nature of the
ADC means that the seed photons for Comptonization must consist of emission
from the disc to the same radial extent as the corona, providing copious
supplies of soft seed photons. We demonstrate the importance of the size of the
ADC to the correct description of Comptonization, and derive the Comptonized
spectrum of a LMXB based on thermal Comptonization of these seed photons and
show that this differs fundamentally from that of the Eastern model which
assumes a cut-off below 1 keV. Finally, we argue that our results are
inconsistent with the assumption often made that the X-ray emission of
accreting Black Holes and Neutron Stars has a common mechanism depending on the
properties of the accretion flow only.Comment: 9 pages, 5 figures, MNRAS in press - final versio
Empty nose syndrome—What do we know?
Empty nose syndrome is a complication of nasal surgery wherein patients develop a persistent, debilitating sense of nasal obstruction and dyspnea despite clear nasal cavities. It is characterized by a discrepancy between prominent subjective symptoms and near total lack of objective findings, making it difficult to diagnose. The pathophysiology of empty nose syndrome is a complex mix of aerodynamic, physiologic, and neurological changes leading to altered airflow and diminished sensory function. Evolving treatment options consist of medical symptom control or surgical reconstruction
Obesity and Breast Cancer: The Roles of Peroxisome Proliferator-Activated Receptor-γ and Plasminogen Activator Inhibitor-1
Breast cancer is the most prominent cancer among females in the United States. There are a number of risk factors associated with development of breast cancer, including consumption of a high-fat diet and obesity. Plasminogen activator inhibitor-1 (PAI-1) is a cytokine upregulated in obesity whose expression is correlated with a poor prognosis in breast cancer. As a key mediator of adipogenesis and regulator of adipokine production, peroxisome proliferator-activated receptor-γ (PPAR-γ) is involved in PAI-1 expression from adipose tissue. We summarize the current knowledge linking PPAR-γ and PAI-1 expression to high-fat diet and obesity in the risk of breast cancer
Discovery of narrow X-ray absorption features from the dipping low-mass X-ray binary X 1624-490 with XMM-Newton
We report the discovery of narrow X-ray absorption features from the dipping
low-mass X-ray binary X 1624-490 during an XMM-Newton observation in 2001
February. The features are identified with the K alpha absorption lines of Fe
xxv and Fe xxvi and have energies of 6.72 +/- 0.03 keV and 7.00 +/- 0.02 keV
and equivalent widths (EWs) of -7.5 +1.7 -6.3 eV and -16.6 +1.9 -5.9 eV,
respectively. The EWs show no obvious dependence on orbital phase, except
during a dip, and correspond to a column of greater than 10^17.3 Fe atom /cm2.
In addition, faint absorption features tentatively identified with Ni xxvii K
alpha and Fe xxvi K beta may be present. A broad emission feature at 6.58 +0.07
-0.04 keV with an EW of 78 +19 -6 eV is also evident. This is probably the 6.4
keV feature reported by earlier missions since fitting a single Gaussian to the
entire Fe-K region gives an energy of 6.39 +0.03 -0.04 keV. A deep absorption
feature is present during the dip with an energy consistent with Fe xxv K
alpha. This is the second dipping LMXRB source from which narrow Fe absorption
features have been observed. Until recently the only X-ray binaries known to
exhibit narrow X-ray absorption lines were two superluminal jet sources and it
had been suggested that these features are related to the jet formation
mechanism. It now appears likely that ionized absorption features may be common
characteristics of accreting systems with accretion disks.Comment: 6 pages. To appear in A&
Peroxisome Proliferator-Activated Receptor-γ Ligands Alter Breast Cancer Cell Motility through Modulation of the Plasminogen Activator System
We investigated peroxisome proliferator-activated receptor-γ (PPAR-γ) ligands effect on cell motility and the plasminogen activator system using normal MCF-10A and malignant MCF-10CA1 cell lines. Ciglitazone reduced both wound-induced migration and chemotaxis. However, the effect was not reversed with pretreatment of cells with the PPAR-γ-specific antagonist GW9662. Immunoblot analysis of conditioned media showed ciglitazone decreased plasminogen activator inhibitor-1 (PAI-1) in both cell lines; this effect was also unaltered by PPAR-γ antagonism. Alternatively, treatment with the ω-6 fatty acid arachidonic acid (ArA), but not the ω-3 fatty acid docosahexanoic acid, increased both MCF-10A cell migration and cell surface uPA activity. Pretreatment with a PPAR-γ antagonist reversed these effects, suggesting that ArA mediates its effect on cell motility and uPA activity through PPAR-γ activation. Collectively, the data suggest PPAR-γ ligands have a differential effect on normal and malignant cell migration and the plasminogen activation system, resulting from PPAR-γ-dependent and PPAR-γ-independent effects
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