3,483 research outputs found
Cerebral Embolism in the Michael Reese Stroke Registry
Infarction Secondary to Cerebral Embolism Was Diagnosed in 127 (23.5%) of 540 Patients in the Michael Reese Stroke Registry. Coronary Artery Disease, Atrial Fibrillation, Valvular Heart Disease, Mitral Annulus Calcification, and Cardiomyopathy Were the Commonest Etiologies. Echocardiography Documented a Potential Embolic Source in 7 Patients Without Previously Known Heart Disease and Clarified the Cardiac Pathology in Many of the Patients with Known Heart Disease. the Left Anterior Circulation Was Affected in 48%, Right Anterior in 37%, and Posterior Circulation in 15% of patients. CT Was Abnormal in 71% of the Patients and Was Approximately Equally Helpful in All Locations. Nineteen Percent of Emboli Presented with a Deficit that Was Other Than Maximal at Onset. Concurrent Systemic Embolism Was Unusual (2.3%). Prognosis Was Somewhat Worse Than in Thrombotic Stroke. Grouping of Patients According to Embolic Source (Intra-Arterial, Cardiac, and Uncertain Source) Showed No Differences in Activity at Onset, Early Course, or in Subsequent Course of the Illness
Current Concepts of Cerebrovascular Disease - Stroke: Stroke and Drug Abuse
This Review Summarizes Available Information Concerning Cerebral Vascular Complications of the Most Commonly Abused Substances and Discusses Possible Mechanisms of Vascular Injury and Cerebral Damage. Although Alcohol is Frequently Abused and May Have Important Cerebrovascular Effects, its Consideration is Beyond the Scope of This Review
Anomalous Noise in the Pseudogap Regime of YBaCuO
An unusual noise component is found near and below about 250 K in the normal
state of underdoped YBCO and Ca-YBCO films. This noise regime, unlike the more
typical noise above 250 K, has features expected for a symmetry-breaking
collective electronic state. These include large individual fluctuators, a
magnetic sensitivity, and aging effects. A possible interpretation in terms of
fluctuating charge nematic order is presented.Comment: 4 pages, 4 figure
Triggered massive-star formation on the borders of Galactic HII regions. IV- Star formation at the periphery of Sh2-212
Aims: We wish to establish whether sequential star formation is taking place
at the periphery of the Galactic HII region Sh2-212.
Methods: We present CO millimetre observations of this region obtained at the
IRAM 30-m telescope to investigate the distribution of associated molecular
material. We also use deep JHK observations obtained at the CFHT to study the
stellar content of the region, and radio observations obtained at the VLA to
look for the presence of an ultra-compact (UC) HII region and for maser
emission.
Results: In the optical, Sh2-212 is spherically symmetric around its central
exciting cluster. This HII region is located along a molecular filament. A
thin, well-defined half ring of molecular material surrounds the brightest part
of the HII region at the rear and is fragmented. The most massive fragment
(~200 solar masses) contains a massive young stellar object displaying a
near-IR excess; its spectral energy distribution indicates a high-mass
(~14solar masses), high-temperature (~30000K), and high-luminosity (~17000
solar luminosities) source. This object ionizes a UC HII region.
Conclusions: Sh2-212 is a good example of massive-star formation triggered
via the collect and collapse process. The massive YSO observed at its periphery
is a good candidate for a massive star formed in isolation.Comment: 12 pages, 14 figures. To be published in A&
Russell-names: an introduction to Millian descriptivism
This essay studies the semantic properties of what I call Russell-names. Russell-names bear intimate semantic relations with descriptive conditions, in consonance with the main tenets of descriptivism. Yet, they are endowed with the semantic properties attributed to ordinary proper names by Millianism: they are rigid and non-indexical devices of direct reference. This is not an essay in natural language semantics, and remains deliberately neutral with respect to the question whether any among the expressions we ordinarily classify as proper names behave as Russell-names. Its aim is rather that of casting a new light on the traditional debate about descriptivism on the one hand, and, on the other, what is commonly understood as a radically anti-descriptivist approach. From the viewpoint of descriptivism, the conceivability of Russell-names provides welcome relief from the pressure exerted by considerations at odds with a flaccid and/or indexical treatment of proper names. Conversely, from a Millian standpoint, the conceivability of Russell-names indicates that the Millian stance, far from providing a meagre picture of names as ‘mere tags’, is at least in principle consistent with the recognition of their semantic bonds with richer descriptive material. The Appendix provides a formal treatment of Russell-names within a model theoretic semantics for indexical intensional languages, developed within an original ‘double-context’ framework
Constraints on a Universal IMF from UV to Near-IR Galaxy Luminosity Densities
We obtain constraints on the slope of a universal stellar initial mass
function (IMF) over a range of cosmic star-formation histories (SFH) using
z=0.1 luminosity densities in the range from 0.2 to 2.2 microns. The age-IMF
degeneracy of integrated spectra of stellar populations can be broken for the
Universe as a whole by using direct measurements of (relative) cosmic SFH from
high-redshift observations. These have only marginal dependence on
uncertainties in the IMF, whereas, fitting to local luminosity densities
depends strongly on both cosmic SFH and the IMF. We fit to these measurements
using population synthesis and find the best-fit IMF power-law slope to be
Gamma=1.15+-0.2 (0.5 < M/M_solar < 120). This slope is in good agreement with
the Salpeter IMF slope (Gamma=1.35). A strong upper limit of Gamma<1.7 is
obtained which effectively rules out the Scalo IMF due to its too low fraction
of high-mass stars. This upper limit is at the 99.7% confidence level if we
assume a closed-box chemical evolution scenario and 95% if we assume constant
solar metallicity. Fitting to the H-alpha line luminosity density, we obtain a
best-fit IMF slope in good agreement with that derived from broadband
measurements. Marginalizing over cosmic SFH and IMF slope, we obtain (95% conf.
ranges, h=1): omega_stars = 1.1-2.0 E-3 for the stellar mass density; rho_sfr =
0.7-4.1 E-2 M_solar/yr/Mpc^3 for the star-formation rate density, and; rho_L =
1.2-1.7 E+35 W/Mpc^3 for the bolometric, attenuated, stellar, luminosity
density (0.09-5 microns). Comparing this total stellar emission with an
estimate of the total dust emission implies a relatively modest average
attenuation in the UV (<=1 magnitude at 0.2 microns).Comment: 16 pages, accepted by Ap
Caudate Infarcts
Eighteen Patients Had Caudate Nucleus Infarcts (10 Left-Sided; 8 Right-Sided). Infarcts Extended into the Anterior Limb of the Internal Capsule in 9 Patients, and Also the Anterior Putamen in 5 Patients. Thirteen Patients Had Motor Signs, Most Often a Slight Transient Hemiparesis. Dysarthria Was Common (11 Patients). Cognitive and Behavioral Abnormalities Were Frequent, and Included Abulia (10 Patients), Agitation and Hyperactivity (7 Patients), Contralateral Neglect (3 Patients, All Right Caudate), and Language Abnormalities (2 Patients, Both Left Caudate). the Majority of Patients Had Risk Factors for Penetrating Artery Disease. Branch Occlusion of Heubner\u27s Artery, or Perforators from the Proximal Anterior or Middle Cerebral Arteries Were the Posited Mechanism of Infarction. © 1990, American Medical Association. All Rights Reserved
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