1,605 research outputs found
Architecture/landscape : an urban sanctuary on Boston Harbor
Thesis (M. Arch.)--Massachusetts Institute of Technology, Dept. of Architecture, 1990.Includes bibliographical references (p. 139).This thesis proposes an urban sanctuary at Chapel Rocks, a peninsula extending into Boston Harbor. The sanctuary includes an ecumenical chapel. restaurant/meeting hall and designed features of the landscape. Several general issues guided this exploration: Architecture and Landscape: How can the design of architecture and the design of landscape be conceived of as equal contributors to the experience of a place? How can the designed landscape build a relationship between human activity and the natural landscape? The nature of a reclaimed landscape: After industrial culture transforms the natural features of a site by cutting, fIlling, drilling, stripping .... how can a new landscape be conceived which acknowledges these changes and the original features of the site? How can a further transformation take place which fuses human aspiration and the specific nature of the place? The nature of an urban sanctuary: How can a site at the edge of a modem industrial city foster an understanding about the ultimate role that nature plays to sustain our physical and spiritual well-being? Can this understanding provide a meeting ground for people of different faiths to share in an experience of the contemplative and sublime?by Richard H. Epstein.M.Arch
Biologically Inspired Feedback Design for Drosophila Flight
We use a biologically motivated model of the Drosophila's flight mechanics and sensor processing to design a feedback control scheme to regulate forward flight. The model used for insect flight is the grand unified fly (GUF) [3] simulation consisting of rigid body kinematics, aerodynamic forces and moments, sensory systems, and a 3D environment model. We seek to design a control algorithm that will convert the sensory signals into proper wing beat commands to regulate forward flight. Modulating the wing beat frequency and mean stroke angle produces changes in the flight envelope. The sensory signals consist of estimates of rotational velocity from the haltere organs and translational velocity estimates from visual elementary motion detectors (EMD's) and matched retinal velocity filters. The controller is designed based on a longitudinal model of the flight dynamics. Feedforward commands are generated based on a desired forward velocity. The dynamics are linearized around this operating point and a feedback controller designed to correct deviations from the operating point. The control algorithm is implemented in the GUF simulator and achieves the desired tracking of the forward reference velocities and exhibits biologically realistic responses
Comparing the cumulative pain patients experience waiting for knee arthroplasty to their postoperative pain
Introduction: Reduction of pain is a major goal of anesthesiologists treating patients undergoing knee arthroplasty. This has been achieved traditionally through the use of regional analgesia. Although these techniques decrease postoperative pain, they inherently do not affect the longstanding pain patients experience as they wait for surgery. Our objectives were to quantify: 1) the decrease in pain achieved by surgical joint replacement; and 2) the decrease in postoperative pain achievable through femoral nerve blocks versus opioids. From a systems-based perspective, we wanted to determine how much reduction in waiting time before surgery would be necessary to achieve an equal cumulative pain decrease (i.e, pain x duration of pain) as that afforded by regional techniques in the immediate postoperative period.
Materials and methods: A systematic review using PubMed was performed to obtain: 1) articles reporting preoperative pain scores for patients awaiting joint arthroplasty; 2) articles with knee arthroplasty patients who received femoral nerve blocks; and 3) articles providing duration on joint arthroplasty waiting lists. Cumulative pain was assessed by the area under the response curve of pain scores vs. time, a methodology that is simple and valid. This was calculated by multiplying mean pain scores by the duration of pain.
Results: The decrease in knee pain subsequent to arthroplasty (6.4/10 vs. 2.9/10) is similar to the decrease in pain afforded by femoral nerve blocks for knee arthroplasty (4.7/10 vs. 2.0/10). Waiting times in many countries exceed 3 months. A decrease in waiting time by about 2 days results in a decrease in the area under the curve of
Conclusion: Reducing waiting time for knee arthroplasty decreases total pain experienced by patients and is one systems-based approach that anesthesiologists could take to relieve pain. Further studies are needed to evaluate how best to accomplish this goal
The impact of changing guidelines on prostate cancer screening in a population-based setting, 2000-2014
Introduction: This study evaluates the potential impact of the publication of conflicting prostate cancer (PCa) screening trial results in 2009 and changes to the US Preventive Services Task Force (USPSTF) guidelines to recommend against screening in 2012 on temporal trends in PSA testing at two participating sites in the NCI-funded Cancer Research Network.
Methods: Study participants were men aged 40-80 without a history of PCa who sought care at Fallon Health (Worcester, MA) or Henry Ford Health System (Detroit, MI) between 2000-2014. We used health claims and electronic health record data to identify men who underwent PSA testing per calendar year. We also examined trends in PSA testing among high-risk men (African-American, family history of PCa). Testing rates were compared between 2000-2008, 2009-2012, and 2013-2014.
Results: From a population of 279,350 eligible men, 133,038 (48%) had at least one PSA test during the study period. Mean age at PSA test was 57 years, which increased over time at both sites. Overall, PSA testing rates rose between 2000-2008 (27-32% of eligible men per year), but declined between 2009-2012 (25% of eligible men). Testing rates declined further in 2013-2014 (23% of eligible men). We observed similar rates of decline in testing for men aged 55-69 and those aged ≥70. High-risk men were less likely to be screened across all time periods, although data was limited.
Conclusions: This analysis of two population-based electronic health datasets provides evidence of a recent decrease in PSA testing, following an increase in the early 2000s. Although we are unable to determine causality, it is plausible that results of recent screening trials and/or changes to the USPSTF guidelines have impacted PSA testing practices over the past 14 years
Light Element Evolution and Cosmic Ray Energetics
Using cosmic-ray energetics as a discriminator, we investigate evolutionary
models of LiBeB. We employ a Monte Carlo code which incorporates the delayed
mixing into the ISM both of the synthesized Fe, due to its incorporation into
high velocity dust grains, and of the cosmic-ray produced LiBeB, due to the
transport of the cosmic rays. We normalize the LiBeB production to the integral
energy imparted to cosmic rays per supernova. Models in which the cosmic rays
are accelerated mainly out of the average ISM significantly under predict the
measured Be abundance of the early Galaxy, the increase in [O/Fe] with
decreasing [Fe/H] notwithstanding. We suggest that this increase could be due
to the delayed mixing of the Fe. But, if the cosmic-ray metals are accelerated
out of supernova ejecta enriched superbubbles, the measured Be abundances are
consistent with a cosmic-ray acceleration efficiency that is in very good
agreement with the current epoch data. We also find that neither the above
cosmic-ray origin models nor a model employing low energy cosmic rays
originating from the supernovae of only very massive progenitors can account
for the Li data at values of [Fe/H] below 2.Comment: latex 19 pages, 2 tables, 10 eps figures, uses aastex.cls natbib.sty
Submitted to the Astrophysical Journa
ESI FTICR-MS Analysis of Larvae from the Marine Sponge Luffariella variabilis
The viviparous Great Barrier Reef sponge Luffariella variabilis (Poléjaeff 1884) contains a range of secondary metabolites, including manoalide (1) and manoalide monoacetate (3). ESI (+) FTICR-MS accurate mass determination has, for the first time, been used to detected the presence of 3 only in an organic extract of a single L. variabilis larva showing that the parentally produced 3 is sequestered in the larva. As 3 has previously been shown to have antibacterial and quorum sensing inhibition activity, and readily converts to 1, which also exhibits similar activity, it may provide a chemical defence against predation and microbial attack
Starquake-induced Magnetic Field and Torque Evolution in Neutron Stars
The persistent increases in spin-down rate offsets seen to accompany glitches
in the Crab and other pulsars suggest increases in the spin-down torque. We
interpret these offsets as due to starquakes occurring as the star spins down
and the rigid crust becomes less oblate. We study the evolution of strain in
the crust, the initiation of starquakes, and possible consequences for magnetic
field and torque evolution. Crust cracking occurs as equatorial material shears
under the compressive forces arising from the star's decreasing circumference,
and matter moves to higher latitudes along a fault inclined to the equator. A
starquake is most likely to originate near one of the two points on the
rotational equator farthest from the magnetic poles. The material breaks along
a fault approximately aligned with the magnetic poles. We suggest that the
observed offsets come about when a starquake perturbs the star's mass
distribution, producing a misalignment of the angular momentum and spin axes.
Subsequently, damped precession to a new rotational state increases the angle
alpha between the rotation and magnetic axes. The resulting increase in
external torque appears as a permanent increase in the spin-down rate. Repeated
starquakes would continue to increase alpha, making the pulsar more of an
orthogonal rotator.Comment: 16 pages, 6 postscript figures, uses AASTeX macros, submitted to ApJ
Letter
Brief of Constitutional Law Scholars as Amici Curiae in Support of Petitioners
Lurking behind the regulatory issues presented by this appeal is a concerted effort to displace the Religious Freedom Restoration Act, 42 U.S.C. § 2000bb et seq. ( RFRA ), with a novel approach that would trivialize a law\u27s burden on religion. The Court should not indulge it.
The critics\u27 argument suffers from several analytical defects that can be remedied by (1) a proper constitutional understanding of RFRA\u27s relationship to the Establishment Clause; (2) an accurate understanding of how the Religion Clauses safeguard third-party interests; and (3) the correct application of these understandings to the Final Rules
Reproducibility of cine displacement encoding with stimulated echoes (DENSE) cardiovascular magnetic resonance for measuring left ventricular strains, torsion, and synchrony in mice
BACKGROUND: Advanced measures of cardiac function are increasingly important to clinical assessment due to their superior diagnostic and predictive capabilities. Cine DENSE cardiovascular magnetic resonance (CMR) is ideal for quantifying advanced measures of cardiac function based on its high spatial resolution and streamlined post-processing. While many studies have utilized cine DENSE in both humans and small-animal models, the inter-test and inter-observer reproducibility for quantification of advanced cardiac function in mice has not been evaluated. This represents a critical knowledge gap for both understanding the capabilities of this technique and for the design of future experiments. We hypothesized that cine DENSE CMR would show excellent inter-test and inter-observer reproducibility for advanced measures of left ventricular (LV) function in mice.
METHODS: Five normal mice (C57BL/6) and four mice with depressed cardiac function (diet-induced obesity) were imaged twice, two days apart, on a 7T ClinScan MR system. Images were acquired with 15-20 frames per cardiac cycle in three short-axis (basal, mid, apical) and two long-axis orientations (4-chamber and 2-chamber). LV strain, twist, torsion, and measures of synchrony were quantified. Images from both days were analyzed by one observer to quantify inter-test reproducibility, while inter-observer reproducibility was assessed by a second observer\u27s analysis of day-1 images. The coefficient of variation (CoV) was used to quantify reproducibility.
RESULTS: LV strains and torsion were highly reproducible on both inter-observer and inter-test bases with CoVs ≤ 15%, and inter-observer reproducibility was generally better than inter-test reproducibility. However, end-systolic twist angles showed much higher variance, likely due to the sensitivity of slice location within the sharp longitudinal gradient in twist angle. Measures of synchrony including the circumferential (CURE) and radial (RURE) uniformity of strain indices, showed excellent reproducibility with CoVs of 1% and 3%, respectively. Finally, peak measures (e.g., strains) were generally more reproducible than the corresponding rates of change (e.g., strain rate).
CONCLUSIONS: Cine DENSE CMR is a highly reproducible technique for quantification of advanced measures of left ventricular cardiac function in mice including strains, torsion and measures of synchrony. However, myocardial twist angles are not reproducible and future studies should instead report torsion
Differences in coronary flow and myocardial metabolism at rest and during pacing between patients with obstructive and patients with nonobstructive hypertrophic cardiomyopathy
Fifty patients with hypertrophic cardiomyopathy underwent invasive study of coronary and myocardial hemodynamics in the basal state and during the stress of pacing. The 23 patients with basal obstruction (average left ventricular outflow gradient, 77 ± 33 mm Hg; left ventricular systolic pressure, 196 ± 33 mm Hg, mean ± 1 SD) had significantly lower coronary resistance (0.85 ± 0.18 versus 1.32 ± 0.44 mm Hg min/ml, p < 0.001) and higher basal coronary flow (106 ± 20 versus 80 ± 25 ml/min, p < 0.001) in the anterior left ventricle, associated with higher regional myocardial oxygen consumption (12.4 ± 3.6 versus 8.9 ± 3.3 ml oxygen/min, p < 0.001) compared with the 27 patients without obstruction (mean left ventricular systolic pressure 134 ± 18 mm Hg, p < 0.001).Myocardial oxygen consumption and coronary blood flow were also significantly higher at paced heart rates of 100 and 130 beats/min (the anginal threshold for 41 of the 50 patients) in patients with obstruction compared with those without. In patients with obstruction, transmural coronary flow reserve was exhausted at a heart rate of 130 beats/min; higher heart rates resulted in more severe metabolic evidence of ischemia with all patients experiencing chest pain, associated with an actual increase in coronary resistance. Patients without obstruction also demonstrated evidence of ischemia at heart rates of 130 and 150 beats/min, with 25 of 27 patients experiencing chest pain. In this group, myocardial ischemia occurred at significantly lower coronary flow, higher coronary resistance and lower myocardial oxygen consumption, suggesting more severely impaired flow delivery in this group compared with those with obstruction. Abnormalities in myocardial oxygen extraction and marked elevation in filling pressures during stress were noted in both groups.Thus, obstruction to left ventricular outflow is associated with high left ventricular systolic pressure and oxygen consumption and therefore has important pathogenetic importance to the precipitation of ischemia in patients with hypertrophic cardiomyopathy. Patients without obstruction may have greater impairment in coronary flow delivery during stress
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