Perturbative corrections to the Gutzwiller mean-field solution of the Mott-Hubbard model

We study the Mott-insulator transition of bosonic atoms in optical lattices. Using perturbation theory, we analyze the deviations from the mean-field Gutzwiller ansatz, which become appreciable for intermediate values of the ratio between hopping amplitude and interaction energy. We discuss corrections to number fluctuations, order parameter, and compressibility. In particular, we improve the description of the short-range correlations in the one-particle density matrix. These corrections are important for experimentally observed expansion patterns, both for bulk lattices and in a confining trap potential.Comment: 10 pages, 10 figue

Circulatory responses to hypoxia in experimental myocardial infarction

Hypoxia affecting circulatory responses in dogs, such as cardiac output, left ventricular dp/dt, and stroke volum

Dynamic model of a spherical robot from first principles

Department Head: Allan Thomson Kirkpatrick.2010 Summer.Includes bibliographical references (pages 77-78).A prototype of a pendulum driven spherical robot has been developed during previous research and shown to exhibit unique dynamic behavior. Starting from first principles, a mathematical model for this spherical robot rolling on flat ground was developed in order to determine if this unique behavior was inherent to spherical robots in general or simply peculiar to this prototype. The complete equations of motion were found using Lagrangian methods, and numerically integrated using computer tools. A 3D simulation program was written to animate the results of integrating the equations. The dynamics apparent in the simulations were found to closely match the observed dynamics of the physical prototype

The AdHOC study of older adults’ adherence to medication in 11 countries

BACKGROUND: Compared with the resources expended developing, evaluating and making clinical decisions about prescribing medication, we know little about what determines whether people take it. Older adults are prescribed more medication than any other group. Poor adherence is a common reason for nonresponse to medication. OBJECTIVES: To investigate cross-nationally the impact of demographic, psychiatric (including cognitive), physical health, behavioural and medication factors on adherence to medication in older adults. METHODS: Researchers interviewed 3881 people over 65 who receive home care services using a structured interview at participants’ places of residence in eleven countries. The main outcome measure was the percentage participants not adherent to medication. RESULTS: 12.5% (n= 456) of people reported they were not fully adherent to medication. Non-adherence was predicted by problem drinking (OR=3.6), not having a doctor review medication (OR=3.3), dementia (OR=1.4 for every one point increase in impairment), good physical health (OR=1.2), resisting care (OR=2.1) being married (OR=2.3) and living in the Czech Republic (OR=4.7) or Germany (OR=1.4). CONCLUSION: People, who screen positive for problem drinking and with dementia, often undiagnosed are less likely to adhere to medication. Therefore doctors should consider dementia and problem drinking when prescribing for older adults. Interventions to improve adherence in older adults might be more effective if 4 targeted at these groups. It is possible that medication review enhances adherence, by improving the patient-doctor relationship, or by emphasising the relevance of medications

Design of a spherical vehicle with flywheel momentum storage for high torque capabilities

Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2008.Includes bibliographical references (leaf 26).A novel method for supplementing the propulsion of a spherical ground vehicle was conceived and developed. The addition of angular momentum storage via counter-rotating control moment gyroscopes is proposed in order to overcome significant limitations in the performance of earlier designs of spherical vehicles. Analysis and design of a fully functioning spherical vehicle incorporating such a mechanism is completed and indicates significantly increased torque capabilities for ascending steep inclines and stairs. A fully functional prototype is built and testing is ongoing to verify its capabilities.by Gregory C. Schroll.S.B

Role of type 1 and type 3 fimbriae in Klebsiella pneumoniae biofilm formation

<p>Abstract</p> <p>Background</p> <p><it>Klebsiella pneumoniae </it>is an important gram-negative opportunistic pathogen causing primarily urinary tract infections, respiratory infections, and bacteraemia. The ability of bacteria to form biofilms on medical devices, e.g. catheters, has a major role in development of many nosocomial infections. Most clinical <it>K. pneumoniae </it>isolates express two types of fimbrial adhesins, type 1 fimbriae and type 3 fimbriae. In this study, we characterized the role of type 1 and type 3 fimbriae in <it>K. pneumoniae </it>biofilm formation.</p> <p>Results</p> <p>Isogenic fimbriae mutants of the clinical <it>K. pneumoniae </it>isolate C3091 were constructed, and their ability to form biofilm was investigated in a flow cell system by confocal scanning laser microscopy. The wild type strain was found to form characteristic biofilm and development of <it>K. pneumoniae </it>biofilm occurred primarily by clonal growth, not by recruitment of planktonic cells. Type 1 fimbriae did not influence biofilm formation and the expression of type 1 fimbriae was found to be down-regulated in biofilm forming cells. In contrast, expression of type 3 fimbriae was found to strongly promote biofilm formation.</p> <p>Conclusion</p> <p>By use of well defined isogenic mutants we found that type 3 fimbriae, but not type 1 fimbriae, strongly promote biofilm formation in <it>K. pneumoniae </it>C3091. As the vast majority of clinical <it>K. pneumoniae </it>isolates express type 3 fimbriae, this fimbrial adhesin may play a significant role in development of catheter associated <it>K. pneumoniae </it>infections.</p

Stable Carbon Isotope Signature of Methane Released From Phytoplankton

Unidad de excelencia María de Maeztu CEX2019-000940-MAquatic ecosystems play an important role in global methane cycling and many field studies have reported methane supersaturation in the oxic surface mixed layer (SML) of the ocean and in the epilimnion of lakes. The origin of methane formed under oxic condition is hotly debated and several pathways have recently been offered to explain the "methane paradox." In this context, stable isotope measurements have been applied to constrain methane sources in supersaturated oxygenated waters. Here we present stable carbon isotope signatures for six widespread marine phytoplankton species, three haptophyte algae and three cyanobacteria, incubated under laboratory conditions. The observed isotopic patterns implicate that methane formed by phytoplankton might be clearly distinguished from methane produced by methanogenic archaea. Comparing results from phytoplankton experiments with isotopic data from field measurements, suggests that algal and cyanobacterial populations may contribute substantially to methane formationobserved in the SML of oceans and lakes

Nanoscale atomic waveguides with suspended carbon nanotubes

We propose an experimentally viable setup for the realization of one-dimensional ultracold atom gases in a nanoscale magnetic waveguide formed by single doubly-clamped suspended carbon nanotubes. We show that all common decoherence and atom loss mechanisms are small guaranteeing a stable operation of the trap. Since the extremely large current densities in carbon nanotubes are spatially homogeneous, our proposed architecture allows to overcome the problem of fragmentation of the atom cloud. Adding a second nanowire allows to create a double-well potential with a moderate tunneling barrier which is desired for tunneling and interference experiments with the advantage of tunneling distances being in the nanometer regime.Comment: Replaced with the published version, 7 pages, 3 figure

Impact of a Viscous Liquid Drop

We simulate the impact of a viscous liquid drop onto a smooth dry solid surface. As in experiments, when ambient air effects are negligible, impact flattens the falling drop without producing a splash. The no-slip boundary condition at the wall produces a boundary layer inside the liquid. Later, the flattening surface of the drop traces out the boundary layer. As a result, the eventual shape of the drop is a "pancake" of uniform thickness except at the rim, where surface tension effects are significant. The thickness of the pancake is simply the height where the drop surface first collides with the boundary layer.Comment: 5 pages, 3 figures, submitted to Physical Review Letter

Research techniques made simple: workflow for searching databases to reduce evidence selection bias in systematic reviews

Clinical trials and basic science studies without statistically significant results are less likely to be published than studies with statistically significant results. Systematic reviews and meta-analyses that omit unpublished data are at high risk of distorted conclusions. Here, we describe methods to search beyond bibliographical databases to reduce evidence selection bias in systematic reviews. Unpublished studies may be identified by searching conference proceedings. Moreover, clinical trial registries—databases of planned and ongoing trials—and regulatory agency websites such as the European Medicine Agency (EMA) and the United States Food and Drug Administration (FDA) may provide summaries of efficacy and safety data. Primary and secondary outcomes are prespecified in trial registries, thus allowing the assessment of outcome reporting bias by comparison with the trial report. The sources of trial data and documents are still evolving, with ongoing initiatives promoting broader access to clinical study reports and individual patient data. There is currently no established methodology to ensure that the multiple sources of information are incorporated. Nonetheless, systematic reviews must adapt to these improvements and cover the new sources in their search strategies