Heart failure is a risk factor for Alzheimer's disease and cerebrovascular disease. In the absence of heart failure, it was hypothesized that left ventricular ejection fraction (LVEF), an indicator ...of cardiac dysfunction, would be associated with preclinical brain magnetic resonance imaging (MRI) and neuropsychological markers of ischemia and Alzheimer disease in the community. Brain MRI, cardiac MRI, neuropsychological, and laboratory data were collected from 1,114 Framingham Heart Study Offspring Cohort participants free from clinical stroke or dementia (aged 40 to 89 years, mean age 67 ± 9 years, 54% women). Neuropsychological and neuroimaging markers of brain aging were related to cardiac MRI–assessed LVEF. In multivariable-adjusted linear regressions, LVEF was not associated with any brain aging variable (p values >0.15). However, LVEF quintile analyses yielded several U-shaped associations. Compared to the referent (quintile 2 to 4), the lowest quintile (quintile 1) LVEF was associated with lower mean cognitive performance, including Visual Reproduction Delayed Recall (β = −0.27, p <0.001) and Hooper Visual Organization Test (β = −0.27, p <0.001). Compared to the referent, the highest quintile (quintile 5) LVEF values also were associated with lower mean cognitive performance, including Logical Memory Delayed Recall (β = −0.18, p = 0.03), Visual Reproduction Delayed Recall (β = −0.17, p = 0.03), Trail Making Test Part B − Part A (β = −0.22, p = 0.02), and Hooper Visual Organization Test (β = −0.20, p = 0.02). Findings were similar when analyses were repeated excluding prevalent cardiovascular disease. In conclusion, although these observational cross-sectional data cannot establish causality, they suggest a nonlinear association between LVEF and measures of accelerated cognitive aging.
Lasercom, also known as free space optical (FSO) communication, has enjoyed a renewal of interest driven by increasing data rate requirements and the crowding of the RF spectrum, affecting both ...commercial and military sectors. Military communications must also deal with intentional or unintentional jamming, as well as frequency allocation restrictions, neither of which affects lasercom. The U.S. Naval Research Laboratory (NRL) has been conducting research on lasercom since 1998 with an emphasis on tactical applications. NRL's lasercom research has covered propagation studies in the maritime domain, component development, and systems demonstrations. NRL has developed both conventional lasercom systems and retro-reflecting systems for small platforms. This paper reviews some of the retro-reflecting work, discusses applications of lasercom in the areas of explosive ordnance disposal (EOD) unmanned ground vehicles (UGVs), and unmanned aerial vehicles (UAVs), and describes future directions.
Between October 1, 1985, and April 1, 1988, we performed balloon aortic valvuloplasty in 170 patients (mean age +/- SD, 77 +/- 5 years) who had symptomatic aortic stenosis. The procedure was ...completed successfully in 168 patients and resulted in significant increases in the mean (+/- SD) aortic-valve area (from 0.6 +/- 0.2 to 0.9 +/- 0.3 cm2) and cardiac output (from 4.6 +/- 3.4 to 4.8 +/- 1.4 liters per minute) and decreases in the peak aortic-valve pressure gradient (from 71 +/- 20 to 36 +/- 14 mm Hg) (P less than 0.01 for all three comparisons). There were six in-hospital deaths, and five patients required early aortic-valve replacement. Follow-up data were available for all patients, for a period averaging 9.1 months. In addition to the 6 patients who died in the hospital, 25 patients died an average of 6.4 +/- 5.3 months after discharge. Symptoms recurred in 44 patients; they were managed by repeat valvuloplasty in 16 patients, by aortic-valve replacement in 17, and by medical therapy in 11. At the most recent follow-up examination, the symptoms of 103 patients had improved after valvuloplasty; this number includes 15 patients with restenosis who successfully underwent redilation. Life-table analysis indicates that the probability of survival 12 months after the procedure was 74 percent. We conclude that balloon aortic valvuloplasty is an effective palliative therapy for some elderly patients with symptomatic aortic stenosis. Symptoms improve in the majority of patients; although restenosis is common, it can be managed in some patients by repeat balloon dilation.
We present a combined photometric and spectroscopic analysis of the star formation history and space density of a sample of 485 luminous, MV− 5 log h < −20.5, field early-type galaxies at redshifts ...0.3 ≲z≲ 0.6. The observed bJori colours as a function of redshift, mean absorption-line strengths and O iiλ3727 emission properties are used to constrain the star formation history of the galaxies. The mean star formation history of the early-type galaxy sample is consistent with an old (zf > 1), passively evolving luminosity-weighted stellar population. 21 per cent of the sample possess detectable O iiλ3727 emission consistent with a low level (≲1 M⊙ yr−1) of on-going star formation. Parametric and non-parametric estimates of the space density of the sample are derived. The integrated luminosity density at z≃ 0.4, allowing only for passive luminosity evolution, is in excellent agreement with the local, (〈z〉= 0.1), luminosity density of early-type galaxies. Overall, the sample properties are consistent with a galaxy formation scenario in which the majority of luminous field early-type galaxies formed at redshifts z > 1 and have largely evolved passively since the formation epoch.
Photometric brown-dwarf classification Skrzypek, N.; Warren, S. J.; Faherty, J. K. ...
Astronomy and astrophysics (Berlin),
02/2015, Letnik:
574
Journal Article
Recenzirano
Odprti dostop
Aims. We present a method, named photo-type, to identify and accurately classify L and T dwarfs onto the standard spectral classification system using photometry alone. This enables the creation of ...large and deep homogeneous samples of these objects efficiently, without the need for spectroscopy. Methods. We created a catalogue of point sources with photometry in 8 bands, ranging from 0.75 to 4.6 μm, selected from an area of 3344 deg2, by combining SDSS, UKIDSS LAS, and WISE data. Sources with 13.0 <J< 17.5, and Y − J> 0.8, were then classified by comparison against template colours of quasars, stars, and brown dwarfs. The L and T templates, spectral types L0 to T8, were created by identifying previously known sources with spectroscopic classifications, and fitting polynomial relations between colour and spectral type. Results. Of the 192 known L and T dwarfs with reliable photometry in the surveyed area and magnitude range, 189 are recovered by our selection and classification method. We have quantified the accuracy of the classification method both externally, with spectroscopy, and internally, by creating synthetic catalogues and accounting for the uncertainties. We find that, brighter than J = 17.5, photo-type classifications are accurate to one spectral sub-type, and are therefore competitive with spectroscopic classifications. The resultant catalogue of 1157 L and T dwarfs will be presented in a companion paper.
A candidate optical Einstein ring Warren, S J; Hewett, P C; Lewis, G F ...
Monthly notices of the Royal Astronomical Society,
01/1996, Letnik:
278, Številka:
1
Journal Article
Recenzirano
We present spectroscopic and imaging observations of a candidate optical Einstein ring. The deflector is a luminous early-type galaxy, M sub B(T) = -20.9 + 5 log h (q0 = 0.1 ), at redshift z = 0.485. ...Superposed on the otherwise normal optical spectrum of the galaxy is a strong emission feature at 5588 A. No other emission lines are evident over the wavelength range 4456-7912 A. Narrow-band imaging of the system at the emission-line wavelength reveals a semicircular arc, radius r = 1.35 arcsec, centered on the peak of the galaxy surface brightness distribution. The properties of the system can be reproduced by a gravitational lens model in which the deflector has a constant mass-to-light ratio (corrected for evolution) of about 20 h, and the source is an intrinsically small, but resolved, object at high redshift, either at z = 3.597 (if the line is Ly-alpha 1216), or at z = 2.607 (if the line is C IV 1549). Alternatives to the lensing explanation, in which the emission feature is associated with forbidden 3727 A, with a velocity difference of 2900 km/s relative to the absorption-line redshift of the galaxy, appear to be extremely improbable. (Author)
Recent studies show that intracellular cholesterol levels can modulate the processing of amyloid precursor protein to A beta peptide. Moreover, cholesterol-rich apoE-containing lipoproteins may also ...promote A beta clearance. Agonists of the liver X receptor (LXR) transcriptionally induce genes involved in intracellular lipid efflux and transport, including apoE. Thus, LXR agonists have the potential to both inhibit APP processing and promote A beta clearance. Here we show that LXR agonist, TO901317, increased hippocampal ABCA1 and apoE and decreased A beta 42 levels in APP transgenic mice. TO901317 had no significant effects on levels of A beta 40, full length APP, or the APP processing products. Next, we examined the effects of TO901317 in the contextual fear conditioning paradigm; TO901317 completely reversed the contextual memory deficit in these mice. These data demonstrate that LXR agonists do not directly inhibit APP processing but rather facilitate the clearance of A beta 42 and may represent a novel therapeutic approach to Alzheimer's disease.
To determine the rate of and indication for cesarean section for women with gestational diabetes mellitus (GDM) compared with glucose-tolerant women.
From a consecutive series of women with GDM seen ...over a 9-year period for medical management, women who had had a cesarean section were identified and the reason for the section determined from a review of the medical record. A control group of women who had had a section were obtained from an existing database of glucose-tolerant women.
The section rate for women with GDM was higher at 19.8% than the 15.6% for glucose-tolerant women. However, after adjustment for age and parity, no significant differences were found. There were also no differences found for the primary indication for section.
In our health area of New South Wales, Australia, women with GDM do not have a higher section rate compared with glucose-tolerant women. Concerns about the diagnosis of GDM leading to an increased rate of obstetric intervention should not be generalized.
To characterize antinuclear antibody (ANA) prevalence according to distinct assay methodologies in a pediatric cohort from Mexico City, and to further examine associations with age and sex.
Serum ANA ...were measured by indirect immunofluorescence assay (IFA) and multiplex immunoassay in 114 children aged 9-17 years. IFA was considered positive at a cutoff titer of ≥1:80. Agreement between assay methods was assessed by kappa statistic. Sensitivity, specificity, and 95% confidence intervals (CIs) of the multiplex were computed with IFA as the reference standard.
Of the 114 children (mean age 14.7 standard deviation 2.1 years; 54 47% female), 18 of 114 (15.8%) were ANA positive by IFA, and 11 of 114 (9.6%) by 11-antigen multiplex assay. ANA prevalence was higher in females compared with males by both of the methods (ratios 1.6-1.9 to 1). Agreement between tests was classified as slight by kappa (κ=0.177 95% CI -0.051, 0.406). The multiplex immunoassay had sensitivity of 22.2% (95% CI 6.4, 47.6) and specificity of 92.7% (95% CI 85.6, 97.0), and failed to capture 3 of 4 (75%) of the high-titer (≥1:1280) IFA-positives.
Up to 15% of children in this general population cohort were ANA positive, with a higher rate of positivity among females according to both assay methods. Substantial discordance in ANA results was found between IFA and multiplex methods, even for high-titer IFA positives. These findings underscore the need to sufficiently account for assay characteristics when interpreting ANA test results, and support IFA as the more appropriate assay for studies of subclinical autoimmunity.
Changes in the height of the tropopause provide a sensitive indicator of human effects on climate. A previous attempt to identify human effects on tropopause height relied on information from ...‘first‐generation’ reanalyses of past weather observations. Climate data from these initial model‐based reanalyses have well‐documented deficiencies, raising concerns regarding the robustness of earlier detection work that employed these data. Here we address these concerns using information from the new second‐generation ERA‐40 reanalysis. Over 1979 to 2001, tropopause height increases by nearly 200 m in ERA‐40, partly due to tropospheric warming. The spatial pattern of height increase is consistent with climate model predictions of the expected response to anthropogenic influences alone, significantly strengthening earlier detection results. Atmospheric temperature changes in two different satellite data sets are more highly correlated with changes in ERA‐40 than with those in a first‐generation reanalysis, illustrating the improved quality of temperature information in ERA‐40. Our results provide support for claims that human activities have warmed the troposphere and cooled the lower stratosphere over the last several decades of the 20th century, and that both of these changes in atmospheric temperature have contributed to an overall increase in tropopause height.
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