Counterbending in a flagellum macromodel

Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2012.Cataloged from PDF version of thesis.Includes bibliographical references (p. 37).The flagellum is one of the most critical biological compenents in nature; it is a basic feature common to many different types of cells and allows for even the most primitive cells to move around. However, the structure of the flagellum is far from simple. The inner core consists of a 9+2 microtubular structure where nine pairs of microtubules are arranged circumferentially with the last pair running down the center. The interstitial space consists of springy proteins and nexin bridges which radially connect the microtubules. Due to this structural complexity and minuscule size, the physical phenomena that occur within the flagellum itself are not well understood. Furthermore, it has been observed that under beam bending conditions a passive sperm flagellum will exhibit counterbend behavior which cannot be explained by current engineering theories. This study created a macroscopic model of the flagellum which allowed deeper exploration of these phenomena. Analysis of material properties and experiments were used to verify the accuracy of the proposed model.by Marty S. Sweeney.S.B

Cost-effectiveness of new MDR-TB regimens: study protocol for the TB-PRACTECAL economic evaluation substudy.

INTRODUCTION: Current treatment regimens for multidrug-resistant tuberculosis (MDR-TB) are long, poorly tolerated and have poor outcomes. Furthermore, the costs of treating MDR-TB are much greater than those for treating drug-susceptible TB, both for health service and patient-incurred costs. Urgent action is needed to identify short, effective, tolerable and cheaper treatments for people with both quinolone-susceptible and quinolone-resistant MDR-TB. We present the protocol for an economic evaluation (PRACTECAL-EE substudy) alongside an ongoing clinical trial (TB-PRACTECAL) aiming to assess the costs to patients and providers of new regimens, as well as their cost-effectiveness and impact on participant poverty levels. This substudy is based on data from the three countries participating in the main trial. METHODS AND ANALYSIS: Primary cost data will be collected from the provider and patient perspectives, following economic best practice. We will estimate the probability that new MDR-TB regimens containing bedaquiline, pretomanid and linezolid are cost-effective from a societal perspective as compared with the standard of care for MDR-TB patients in Uzbekistan, South Africa and Belarus. Analysis uses a Markov model populated with primary cost and outcome data collected at each study site. We will also estimate the impact of new regimens on prevalence of catastrophic patient costs due to TB. ETHICS AND DISSEMINATION: Ethical approval has been obtained from the London School of Hygiene & Tropical Medicine and Médecins Sans Frontières. Local ethical approval will be sought in each study site. The results of the economic evaluation will be shared with the country health authorities and published in a peer-reviewed journal. TRIAL REGISTRATION NUMBER: ClinicalTrials.gov Registry (NCT04207112); Pre-results

Effect of Intensive Versus Standard Blood Pressure Control on Stroke Subtypes

In the SPRINT (Systolic Blood Pressure Intervention Trial), the number of strokes did not differ significantly by treatment group. However, stroke subtypes have heterogeneous causes that could respond differently to intensive blood pressure control. SPRINT participants (N=9361) were randomized to target systolic blood pressures of \u3c120 mm Hg (intensive treatment) compared with \u3c140 mm Hg (standard treatment). We compared incident hemorrhage, cardiac embolism, large- and small-vessel infarctions across treatment arms. Participants randomized to the intensive arm had mean systolic blood pressures of 121.4 mm Hg in the intensive arm (N=4678) and 136.2 mm Hg in the standard arm (N=4683) at one year. Sixty-nine strokes occurred in the intensive arm and 78 in the standard arm when SPRINT was stopped. The breakdown of stroke subtypes across treatment arms included hemorrhagic (intensive treatment, n=6, standard treatment, n=7) and ischemic stroke subtypes (large artery atherosclerosis: intensive treatment n=11, standard treatment, n=13; cardiac embolism: intensive treatment n=11, standard treatment n=15; small artery occlusion: intensive treatment n=8, standard treatment n=8; other ischemic stroke: intensive treatment n=3, standard treatment n=1). Fewer strokes occurred among participants without prior cardiovascular disease in the intensive (n=43) than the standard arm (n=61), but the difference did not reach predefined statistical significance level of 0.05 (P=0.09). The interaction between baseline cardiovascular risk factor status and treatment arm on stroke risk did not reach significance (P=0.05). Similar numbers of stroke subtypes occurred in the intensive BP control and standard control arms of SPRINT

Stromal cell-derived factor and granulocyte-monocyte colony-stimulating factor form a combined neovasculogenic therapy for ischemic cardiomyopathy

ObjectiveIschemic heart failure is an increasingly prevalent global health concern with major morbidity and mortality. Currently, therapies are limited, and novel revascularization methods might have a role. This study examined enhancing endogenous myocardial revascularization by expanding bone marrow-derived endothelial progenitor cells with the marrow stimulant granulocyte-monocyte colony-stimulating factor and recruiting the endothelial progenitor cells with intramyocardial administration of the potent endothelial progenitor cell chemokine stromal cell-derived factor.MethodsIschemic cardiomyopathy was induced in Lewis rats (n = 40) through left anterior descending coronary artery ligation. After 3 weeks, animals were randomized into 4 groups: saline control, granulocyte-monocyte colony-stimulating factor only (GM-CSF only), stromal cell-derived factor only (SDF only), and combined stromal cell-derived factor/granulocyte-monocyte colony-stimulating factor (SDF/GM-CSF) (n = 10 each). After another 3 weeks, hearts were analyzed for endothelial progenitor cell density by endothelial progenitor cell marker colocalization immunohistochemistry, vasculogenesis by von Willebrand immunohistochemistry, ventricular geometry by hematoxylin-and-eosin microscopy, and in vivo myocardial function with an intracavitary pressure-volume conductance microcatheter.ResultsThe saline control, GM-CSF only, and SDF only groups were equivalent. Compared with the saline control group, animals in the SDF/GM-CSF group exhibited increased endothelial progenitor cell density (21.7 ± 3.2 vs 9.6 ± 3.1 CD34+/vascular endothelial growth factor receptor 2–positive cells per high-power field, P = .01). There was enhanced vascularity (44.1 ± 5.5 versus 23.8 ± 2.2 von Willebrand factor-positive vessels per high-power field, P = .007). SDF/GM-CSF group animals experienced less adverse ventricular remodeling, as manifested by less cavitary dilatation (9.8 ± 0.1 mm vs 10.1 ± 0.1 mm [control], P = .04) and increased border-zone wall thickness (1.78 ± 0.19 vs 1.41 ± 0.16 mm [control], P = .03). (SDF/GM-CSF group animals had improved cardiac function compared with animals in the saline control group (maximum pressure: 93.9 ± 3.2 vs 71.7 ± 3.1 mm Hg, P < .001; maximum dP/dt: 3513 ± 303 vs 2602 ± 201 mm Hg/s, P < .05; cardiac output: 21.3 ± 2.7 vs 13.3 ± 1.3 mL/min, P < .01; end-systolic pressure-volume relationship slope: 1.7 ± 0.4 vs 0.5 ± 0.2 mm Hg/μL, P < .01.)ConclusionThis novel revascularization strategy of bone marrow stimulation and intramyocardial delivery of the endothelial progenitor cell chemokine stromal cell-derived factor yielded significantly enhanced myocardial endothelial progenitor cell density, vasculogenesis, geometric preservation, and contractility in a model of ischemic cardiomyopathy

Alumni Association Bulletin of the School of Nursing, 1976

Alumni Calendar The President\u27s Message Officers and Chairpersons of Committees Financial Report Annual Reports New Surgical Concept for Laryngeal Cancer Computerized Transaxial X-ray Scanner Dental Health Center The Winged Ox of St. Luke Pictures - New Building Committee Reports Resume of Alumni Minutes Ways and Means Report Alumni News Class News Names and Addresses of 1976 Graduates School of Nursing 1976 Awards Marriages Births In Memoriam - List of Alumni In Memoriam - Dr. Peter A. Herbut In Memoriam - Miss Katherine Childs Change of Address Notice Notice

LSST Science Book, Version 2.0

A survey that can cover the sky in optical bands over wide fields to faint magnitudes with a fast cadence will enable many of the exciting science opportunities of the next decade. The Large Synoptic Survey Telescope (LSST) will have an effective aperture of 6.7 meters and an imaging camera with field of view of 9.6 deg^2, and will be devoted to a ten-year imaging survey over 20,000 deg^2 south of +15 deg. Each pointing will be imaged 2000 times with fifteen second exposures in six broad bands from 0.35 to 1.1 microns, to a total point-source depth of r~27.5. The LSST Science Book describes the basic parameters of the LSST hardware, software, and observing plans. The book discusses educational and outreach opportunities, then goes on to describe a broad range of science that LSST will revolutionize: mapping the inner and outer Solar System, stellar populations in the Milky Way and nearby galaxies, the structure of the Milky Way disk and halo and other objects in the Local Volume, transient and variable objects both at low and high redshift, and the properties of normal and active galaxies at low and high redshift. It then turns to far-field cosmological topics, exploring properties of supernovae to z~1, strong and weak lensing, the large-scale distribution of galaxies and baryon oscillations, and how these different probes may be combined to constrain cosmological models and the physics of dark energy.Comment: 596 pages. Also available at full resolution at http://www.lsst.org/lsst/sciboo

High-resolution net and gross biological production during a Celtic Sea spring bloom

Shelf seas represent only 10% of the ocean area, but support up to 30% of all oceanic primary production. There are few measurements of shelf-sea biological production at high spatial and temporal resolution in such heterogeneous and physically dynamic systems. Here, we use dissolved oxygen-to-argon (O2/Ar) ratios and oxygen triple isotopes (16O, 17O, 18O) to estimate net and gross biological production in the Celtic Sea during spring 2015. O2/Ar ratios were measured continuously using a shipboard membrane inlet mass spectrometer (MIMS). Additional discrete water samples from CTD hydrocasts were used to measure O2/Ar depth profiles and the δ(17O) and δ(18O) values of dissolved O2. These high-resolution data were combined with wind-speed based gas exchange parameterisations to calculate biologically driven air-sea oxygen fluxes. After correction for disequilibrium terms and diapycnal diffusion, these fluxes yielded estimates of net community (N(O2/Ar)) and gross O2 production (G(17O)). N(O2/Ar) was spatially heterogeneous and showed predominantly autotrophic conditions, with an average of (33±41) mmol m-2 d-1. G(17O) showed high variability between 0 and 424 mmol m-2 d-1. The ratio of N(O2/Ar) to G(17O), ƒ(O2), was (0.18±0.03) corresponding to 0.34±0.06 in carbon equivalents. We also observed rapid temporal changes in N(O2/Ar), e.g. an increase of 80 mmol m-2 d-1 in less than 6 hours during the spring bloom, highlighting the importance of high-resolution biological production measurements. Such measurements will help reconcile the differences between satellite and in situ productivity observations, and improve our understanding of the biological carbon pump

LSST: from Science Drivers to Reference Design and Anticipated Data Products

(Abridged) We describe here the most ambitious survey currently planned in the optical, the Large Synoptic Survey Telescope (LSST). A vast array of science will be enabled by a single wide-deep-fast sky survey, and LSST will have unique survey capability in the faint time domain. The LSST design is driven by four main science themes: probing dark energy and dark matter, taking an inventory of the Solar System, exploring the transient optical sky, and mapping the Milky Way. LSST will be a wide-field ground-based system sited at Cerro Pach\'{o}n in northern Chile. The telescope will have an 8.4 m (6.5 m effective) primary mirror, a 9.6 deg$^2$ field of view, and a 3.2 Gigapixel camera. The standard observing sequence will consist of pairs of 15-second exposures in a given field, with two such visits in each pointing in a given night. With these repeats, the LSST system is capable of imaging about 10,000 square degrees of sky in a single filter in three nights. The typical 5$\sigma$ point-source depth in a single visit in $r$ will be $\sim 24.5$ (AB). The project is in the construction phase and will begin regular survey operations by 2022. The survey area will be contained within 30,000 deg$^2$ with $\delta<+34.5^\circ$, and will be imaged multiple times in six bands, $ugrizy$, covering the wavelength range 320--1050 nm. About 90\% of the observing time will be devoted to a deep-wide-fast survey mode which will uniformly observe a 18,000 deg$^2$ region about 800 times (summed over all six bands) during the anticipated 10 years of operations, and yield a coadded map to $r\sim27.5$. The remaining 10\% of the observing time will be allocated to projects such as a Very Deep and Fast time domain survey. The goal is to make LSST data products, including a relational database of about 32 trillion observations of 40 billion objects, available to the public and scientists around the world.Comment: 57 pages, 32 color figures, version with high-resolution figures available from https://www.lsst.org/overvie