2,680 research outputs found
Security in Northeast Asia: A Trilateral Alternative
Thanks to the TV comedy series M*A*S*l I, the US military presence in Korea is arguably the best known but least understood component of the United States\u27 strategic presence in Asia. In the wake of the American debacle in Vietnam juxtaposed with the economic and other successes of the United States\u27 South Korean protégé, it comes as no surprise to Americans that Washington wants to keep US forces steadfastly committed in Korea-a place where they fought and, after a fashion, won
Prospects for an increased naval role for the Republic of Korea in Northeast Asian security
The Republic of Korea's robust economy and diverse global interests are encouraging ROK officials and scholars to contemplate a broader range of security interests than they have in the past. ROK naval options are included in that spectrum. Though the ROK remains preoccupied by a continental orientation, focused on the North Korean threat, defense intellectuals in South Korea are interested in the following broader security themes: SLOC defenses, regional naval security, industrial cooperation in naval areas, and the possibilities of a Korean maritime strategy. The ROK seems interested in expanding its naval horizons and capabilities, but those aspirations may be tempered by changes in Northeast Asia which may alter the context in which Seoul must implement its policies. Keywords: Sea lanes of communications; Maritime strategy. (edc)http://archive.org/details/prospectsforincr00olseApproved for public release; distribution is unlimited
Absolute Magnitudes and Colors of RR Lyrae stars in DECam Passbands from Photometry of the Globular Cluster M5
We characterize the absolute magnitudes and colors of RR Lyrae stars in the
globular cluster M5 in the ugriz filter system of the Dark Energy Camera
(DECam). We provide empirical Period-Luminosity (P-L) relationships in all 5
bands based on 47 RR Lyrae stars of the type ab and 14 stars of the type c. The
P-L relationships were found to be better constrained for the fundamental mode
RR Lyrae stars in the riz passbands, with dispersion of 0.03, 0.02 and 0.02
magnitudes, respectively. The dispersion of the color at minimum light was
found to be small, supporting the use of this parameter as a means to obtain
accurate interstellar extinctions along the line of sight up to the distance of
the RR Lyrae star. We found a trend of color at minimum light with pulsational
period that, if taken into account, brings the dispersion in color at minimum
light to < 0.016 magnitudes for the (r-i), (i-z), and (r-z) colors. These
calibrations will be very useful for using RR Lyrae stars from DECam
observations as both standard candles for distance determinations and color
standards for reddening measurements.Comment: Accepted for publication in A
Application of endograft to treat thoracic aortic pathologies: A single center experience
PurposeTo evaluate our experience of thoracic endoluminal graft (ELG) repair of various thoracic aortic pathologies using a commercially available device approved by the Food and Drug Administration. Our patient population includes patients eligible for open surgical repair and those with prohibitive surgical risk.MethodsFrom March 1998 to March 2006, endovascular stent repair of the thoracic aorta was performed on 406 patients with 324 patients (median age 72; 200 male) receiving the Gore Excluder endograft. Patient demographics, procedural characteristics, complications, including endoleak, spinal cord ischemia, and mortality, were retrospectively reviewed during follow-up. All patients were followed with chest computer tomography at 6 months and yearly. Statistical analysis was performed utilizing the SPSS Windows 11.0 program. Logistic regression (univariate) analysis used to identify risk factors for paraplegia; analysis of variance (ANOVA) for endoleak distribution; and χ2 used to analyze variables. Survival analysis was done using SAS version 9.1 (SAS Institute, Cary, NC).ResultsThree hundred twenty-four patients were treated with Gore Excluder graft between March 1998 and March 2006. One hundred fifty-seven patients (48.5%) had atherosclerotic aneurysms, 82 (25.3%) had dissections type B (DTB), 34 (10.5%) had penetrating ulcers (PU), 26 (8.0%) with pseudoaneurysms (PSA), 11 (3.4%) had transections (MVAT), 9 (2.8%) aorto-bronchial fistulas (AoBF), 4 (1.2%) embolization, and 1 (0.3%) aorto-esophageal fistula (AoEF). Preoperative aneurysm sac size in TAA ranged from 5 to 12 centimeters, average size 6.3 cm. Sac shrinkage occurred in 65% (102 of 157) of patients. Average postoperative sac size of 5.4 cm in a mean follow-up of 20.4 months. One hundred cases (31.5%) were nonelective; 49 (15.1%) were ruptures. Overall complication was 22.7%, 14.2% (46) in elective cases and 8.5% (28) in nonelective cases. Paraplegia occurred in five (1.5%) patients and paresis in three (0.9%); two of the latter improved and one resolved completely prior to discharge. Incidence of paraplegia was statistically significant (P value < .05) with retroperitoneal approach, perioperative blood loss greater than 1000 cc, and aortic coverage greater than 40 cm. Early endoleaks included 18 (5.5%) type I, four (1.2%) type II, and two (0.6%) type III. Thirty-day mortality was 5.5% (18 related deaths, including three intraoperative deaths). A log rank test did not find statistical differences in actuarial survival with 30-day related mortality between TAA and other pathologies (P = .29) or between DTB and other pathologies (P = .97). Late mortality was 9.6% with 31 unrelated deaths. Follow-up ranged between 1 month and 70 months, average 17 months.ConclusionsEndoluminal grafting is a feasible alternative to open surgical repair for thoracic aortic pathologies. After more than 300 cases, 30-day morbidity and mortality compares favorably with open repair. Paraplegia remains low as a complication and increases in incidence with retroperitoneal approach, increased perioperative blood loss, and increased aortic coverage
Descriptive and Inferential Statistics in Undergraduate Data Science Research Projects
Undergraduate data science research projects form an integral component of the Wesley College science and mathematics curriculum. In this chapter, we provide examples for hypothesis testing, where statistical methods or strategies are coupled with methodologies using interpolating polynomials, probability and the expected value concept in statistics. These are areas where real-world critical thinking and decision analysis applications peak a student’s interest
Subunit Compensation and Plasticity of Synaptic GABAA Receptors Induced by Ethanol in α4 Subunit Knockout Mice
There is considerable evidence that ethanol (EtOH) potentiates γ-aminobutyric acid type A receptor (GABAAR) action, but only GABAARs containing δ subunits appear sensitive to low millimolar EtOH. The α4 and δ subunits co-assemble into GABAARs which are relatively highly expressed at extrasynaptic locations in the dentate gyrus where they mediate tonic inhibition. We previously demonstrated reversible- and time-dependent changes in GABAAR function and subunit composition in rats after single-dose EtOH intoxication. We concluded that early tolerance to EtOH occurs by over-activation and subsequent internalization of EtOH-sensitive extrasynaptic α4βδ-GABAARs. Based on this hypothesis, any highly EtOH-sensitive GABAARs should be subject to internalization following exposure to suitably high EtOH doses. To test this, we studied the GABAARs in mice with a global deletion of the α4 subunit (KO). The dentate granule cells of these mice exhibited greatly reduced tonic currents and greatly reduced potentiation by acutely applied EtOH, whereas synaptic currents showed heightened sensitivity to low EtOH concentrations. The hippocampus of naive KO mice showed reduced δ subunit protein levels, but increased α2, and γ2 levels compared to wild-type (WT) controls, suggesting at least partial compensation by these subunits in synaptic, highly EtOH-sensitive GABAARs of KO mice. In WT mice, cross-linking and Western blot analysis at 1 h after an EtOH challenge (3.5 g/kg, i.p.) revealed increased intracellular fraction of the α1, α4, and δ, but not α2, α5, or γ2 subunits. By contrast, we observed significant internalization of α1, α2, δ, and γ2 subunits after a similar EtOH challenge in KO mice. Synaptic currents from naïve KO mice were more sensitive to potentiation by zolpidem (0.3 μM, requiring α1/α2, inactive at α4/5 GABAARs) than those from naïve WT mice. At 1 h after EtOH, synaptic currents of WT mice were unchanged, whereas those of KO mice were significantly less sensitive to zolpidem, suggesting decreases in functional α1/2βγ GABAARs. These data further support our hypothesis that EtOH intoxication induces GABAAR plasticity via internalization of highly EtOH-sensitive GABAARs
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