1,968 research outputs found
Enhanced error estimator based on a nearly equilibrated moving least squares recovery technique for FEM and XFEM
In this paper a new technique aimed to obtain accurate estimates of the error
in energy norm using a moving least squares (MLS) recovery-based procedure is
presented. We explore the capabilities of a recovery technique based on an
enhanced MLS fitting, which directly provides continuous interpolated fields,
to obtain estimates of the error in energy norm as an alternative to the
superconvergent patch recovery (SPR). Boundary equilibrium is enforced using a
nearest point approach that modifies the MLS functional. Lagrange multipliers
are used to impose a nearly exact satisfaction of the internal equilibrium
equation. The numerical results show the high accuracy of the proposed error
estimator
Femtosecond control of electric currents at the interfaces of metallic ferromagnetic heterostructures
The idea to utilize not only the charge but also the spin of electrons in the
operation of electronic devices has led to the development of spintronics,
causing a revolution in how information is stored and processed. A novel
advancement would be to develop ultrafast spintronics using femtosecond laser
pulses. Employing terahertz (10 Hz) emission spectroscopy, we
demonstrate optical generation of spin-polarized electric currents at the
interfaces of metallic ferromagnetic heterostructures at the femtosecond
timescale. The direction of the photocurrent is controlled by the helicity of
the circularly polarized light. These results open up new opportunities for
realizing spintronics in the unprecedented terahertz regime and provide new
insights in all-optical control of magnetism.Comment: 3 figures and 2 tables in the main tex
Non-reducible knee dislocation with interposition of the vastus medialis muscle
Irreducibility of the knee following complete dislocation is a rare event determined by the interposition of various capsulo-ligamentous structures in the joint space. Such cases often require urgent surgical treatment. We report the case of a healthy 70-year-old man with a sprain of the left knee that occurred after a sports trauma. The patient showed knee dislocation with multiple ligamentous injuries and articular block due to interposition of a portion of the vastus medialis muscle. After arthroscopic evaluation, we performed surgical treatment to free the muscle, regularize the medial meniscus and suture the posterior and medial capsule and ligaments; the cruciate ligaments were not treated. The most interesting aspect of the articular damage in this case was a wide detachment of the vastus medialis muscle with intra-articular dislocation. The decision to treat only the posterior lesions and allow the healing of the front ones by rehabilitation treatment was supported by full functional recovery and return to sports activity
Disentangling astroglial physiology with a realistic cell model in silico
Electrically non-excitable astroglia take up neurotransmitters, buffer extracellular K+ and generate Ca2+ signals that release molecular regulators of neural circuitry. The underlying machinery remains enigmatic, mainly because the sponge-like astrocyte morphology has been difficult to access experimentally or explore theoretically. Here, we systematically incorporate multi-scale, tri-dimensional astroglial architecture into a realistic multi-compartmental cell model, which we constrain by empirical tests and integrate into the NEURON computational biophysical environment. This approach is implemented as a flexible astrocyte-model builder ASTRO. As a proof-of-concept, we explore an in silico astrocyte to evaluate basic cell physiology features inaccessible experimentally. Our simulations suggest that currents generated by glutamate transporters or K+ channels have negligible distant effects on membrane voltage and that individual astrocytes can successfully handle extracellular K+ hotspots. We show how intracellular Ca2+ buffers affect Ca2+ waves and why the classical Ca2+ sparks-and-puffs mechanism is theoretically compatible with common readouts of astroglial Ca2+ imaging
Stromalâepithelial interactions influence prostate cancer cell invasion by altering the balance of metallopeptidase expression
Outcomes associated with matching patients' treatment preferences to physicians' recommendations: study methodology
<p>Abstract</p> <p>Background</p> <p>Patients often express strong preferences for the forms of treatment available for their disease. Incorporating these preferences into the process of treatment decision-making might improve patients' adherence to treatment, contributing to better outcomes. We describe the methodology used in a study aiming to assess treatment outcomes when patients' preferences for treatment are closely matched to recommended treatments.</p> <p>Method</p> <p>Participants included patients with moderate and severe psoriasis attending outpatient dermatology clinics at the University Medical Centre Mannheim, University of Heidelberg, Germany. A self-administered online survey used conjoint analysis to measure participants' preferences for psoriasis treatment options at the initial study visit. Physicians' treatment recommendations were abstracted from each participant's medical records. The Preference Matching Index (PMI), a measure of concordance between the participant's preferences for treatment and the physician's recommended treatment, was determined for each participant at t<sub>1 </sub>(initial study visit). A clinical outcome measure, the Psoriasis Area and Severity Index, and two participant-derived outcomes assessing treatment satisfaction and health related quality of life were employed at t<sub>1</sub>, t<sub>2 </sub>(twelve weeks post-t<sub>1</sub>) and t<sub>3 </sub>(twelve weeks post-t<sub>2</sub>). Change in outcomes was assessed using repeated measures analysis of variance. The association between participants' PMI scores at t<sub>1 </sub>and outcomes at t<sub>2 </sub>and t<sub>3 </sub>was evaluated using multivariate regressions analysis.</p> <p>Discussion</p> <p>We describe methods for capturing concordance between patients' treatment preferences and recommended treatment and for assessing its association with specific treatment outcomes. The methods are intended to promote the incorporation of patients' preferences in treatment decision-making, enhance treatment satisfaction, and improve treatment effectiveness through greater adherence.</p
Biphasic Electrical Currents Stimulation Promotes both Proliferation and Differentiation of Fetal Neural Stem Cells
The use of non-chemical methods to differentiate stem cells has attracted
researchers from multiple disciplines, including the engineering and the
biomedical fields. No doubt, growth factor based methods are still the most
dominant of achieving some level of proliferation and differentiation control -
however, chemical based methods are still limited by the quality, source, and
amount of the utilized reagents. Well-defined non-chemical methods to
differentiate stem cells allow stem cell scientists to control stem cell biology
by precisely administering the pre-defined parameters, whether they are
structural cues, substrate stiffness, or in the form of current flow. We have
developed a culture system that allows normal stem cell growth and the option of
applying continuous and defined levels of electric current to alter the cell
biology of growing cells. This biphasic current stimulator chip employing ITO
electrodes generates both positive and negative currents in the same culture
chamber without affecting surface chemistry. We found that biphasic electrical
currents (BECs) significantly increased the proliferation of fetal neural stem
cells (NSCs). Furthermore, BECs also promoted the differentiation of fetal NSCs
into neuronal cells, as assessed using immunocytochemistry. Our results clearly
show that BECs promote both the proliferation and neuronal differentiation of
fetal NSCs. It may apply to the development of strategies that employ NSCs in
the treatment of various neurodegenerative diseases, such as Alzheimer's
and Parkinson's diseases
Biphasic Electrical Currents Stimulation Promotes both Proliferation and Differentiation of Fetal Neural Stem Cells
The use of non-chemical methods to differentiate stem cells has attracted
researchers from multiple disciplines, including the engineering and the
biomedical fields. No doubt, growth factor based methods are still the most
dominant of achieving some level of proliferation and differentiation control -
however, chemical based methods are still limited by the quality, source, and
amount of the utilized reagents. Well-defined non-chemical methods to
differentiate stem cells allow stem cell scientists to control stem cell biology
by precisely administering the pre-defined parameters, whether they are
structural cues, substrate stiffness, or in the form of current flow. We have
developed a culture system that allows normal stem cell growth and the option of
applying continuous and defined levels of electric current to alter the cell
biology of growing cells. This biphasic current stimulator chip employing ITO
electrodes generates both positive and negative currents in the same culture
chamber without affecting surface chemistry. We found that biphasic electrical
currents (BECs) significantly increased the proliferation of fetal neural stem
cells (NSCs). Furthermore, BECs also promoted the differentiation of fetal NSCs
into neuronal cells, as assessed using immunocytochemistry. Our results clearly
show that BECs promote both the proliferation and neuronal differentiation of
fetal NSCs. It may apply to the development of strategies that employ NSCs in
the treatment of various neurodegenerative diseases, such as Alzheimer's
and Parkinson's diseases
Alpha-Toxin Induces Programmed Cell Death of Human T cells, B cells, and Monocytes during USA300 Infection
This investigation examines the influence of alpha-toxin (Hla) during USA300 infection of human leukocytes. Survival of an USA300 isogenic deletion mutant of hla (USA300Îhla) in human blood was comparable to the parental wild-type strain and polymorphonuclear leukocyte (PMN) plasma membrane permeability caused by USA300 did not require Hla. Flow cytometry analysis of peripheral blood mononuclear cells (PBMCs) following infection by USA300, USA300Îhla, and USA300Îhla transformed with a plasmid over-expressing Hla (USA300Îhla Comp) demonstrated this toxin plays a significant role inducing plasma membrane permeability of CD14+, CD3+, and CD19+ PBMCs. Rapid plasma membrane permeability independent of Hla was observed for PMNs, CD14+ and CD19+ PBMCs following intoxication with USA300 supernatant while the majority of CD3+ PBMC plasma membrane permeability induced by USA300 required Hla. Addition of recombinant Hla to USA300Îhla supernatant rescued CD3+ and CD19+ PBMC plasma membrane permeability generated by USA300 supernatant. An observed delay in plasma membrane permeability caused by Hla in conjunction with Annexin V binding and ApoBrdU Tunel assays examining PBMCs intoxicated with recombinant Hla or infected with USA300, USA300Îhla, USA300Îhla Comp, and USA300ÎsaeR/S suggest Hla induces programmed cell death of monocytes, B cells, and T cells that results in plasma membrane permeability. Together these findings underscore the importance of Hla during S. aureus infection of human tissue and specifically demonstrate Hla activity during USA300 infection triggers programmed cell death of human monocytes, T cells and B cells that leads to plasma membrane permeability
Measurement of the inclusive and dijet cross-sections of b-jets in pp collisions at sqrt(s) = 7 TeV with the ATLAS detector
The inclusive and dijet production cross-sections have been measured for jets
containing b-hadrons (b-jets) in proton-proton collisions at a centre-of-mass
energy of sqrt(s) = 7 TeV, using the ATLAS detector at the LHC. The
measurements use data corresponding to an integrated luminosity of 34 pb^-1.
The b-jets are identified using either a lifetime-based method, where secondary
decay vertices of b-hadrons in jets are reconstructed using information from
the tracking detectors, or a muon-based method where the presence of a muon is
used to identify semileptonic decays of b-hadrons inside jets. The inclusive
b-jet cross-section is measured as a function of transverse momentum in the
range 20 < pT < 400 GeV and rapidity in the range |y| < 2.1. The bbbar-dijet
cross-section is measured as a function of the dijet invariant mass in the
range 110 < m_jj < 760 GeV, the azimuthal angle difference between the two jets
and the angular variable chi in two dijet mass regions. The results are
compared with next-to-leading-order QCD predictions. Good agreement is observed
between the measured cross-sections and the predictions obtained using POWHEG +
Pythia. MC@NLO + Herwig shows good agreement with the measured bbbar-dijet
cross-section. However, it does not reproduce the measured inclusive
cross-section well, particularly for central b-jets with large transverse
momenta.Comment: 10 pages plus author list (21 pages total), 8 figures, 1 table, final
version published in European Physical Journal
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