295 research outputs found
Renormalization of the electron-phonon interaction: a reformulation of the BCS-gap equation
A recently developed renormalization approach is used to study the
electron-phonon coupling in many-electron systems. By starting from an
Hamiltonian which includes a small gauge symmetry breaking field, we directly
derive a BCS-like equation for the energy gap from the renormalization
approach. The effective electron-electron interaction for Cooper pairs does not
contain any singularities. Furthermore, it is found that phonon-induced
particle-hole excitations only contribute to the attractive electron-electron
interaction if their energy difference is smaller than the phonon energy.Comment: 8 pages, version to appear in Eur. Phys. J.
Technical Note: Field experiences using UV/VIS sensors for high-resolution monitoring of nitrate in groundwater
peer-reviewedTwo different in situ spectrophotometers are compared that were used in the field to determine nitrate-nitrogen (NO3-N) concentrations at two distinct spring discharge sites. One sensor was a double wavelength spectrophotometer (DWS) and the other a multiple wavelength spectrophotometer (MWS). The objective of the study was to review the hardware options, determine ease of calibration, accuracy, influence of additional substances and to assess positive and negative aspects of the two sensors as well as troubleshooting and trade-offs. Both sensors are sufficient to monitor highly time-resolved NO3-N concentrations in emergent groundwater. However, the chosen path length of the sensors had a significant influence on the sensitivity and the range of detectable NO3-N. The accuracy of the calculated NO3-N concentrations of the sensors can be affected if the content of additional substances such as turbidity, organic matter, nitrite or hydrogen carbonate significantly varies after the sensors have been calibrated to a particular water matrix. The MWS offers more possibilities for calibration and error detection but requires more expertise compared with the DWS.The authors would like to acknowledge
the Teagasc Walsh Fellowship scheme for funding the study in Ireland, and the German federal Ministry of Education and Research (BMBF) for sponsoring the SMART-project (grant
no. 02WM1079-1086, 02WM1211-1212) for the study in Jordan.Teagasc Walsh Fellowship Programm
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Contractile deficits in engineered cardiac microtissues as a result of MYBPC3 deficiency and mechanical overload.
The integration of in vitro cardiac tissue models, human induced pluripotent stem cells (hiPSCs) and genome-editing tools allows for the enhanced interrogation of physiological phenotypes and recapitulation of disease pathologies. Here, using a cardiac tissue model consisting of filamentous three-dimensional matrices populated with cardiomyocytes derived from healthy wild-type (WT) hiPSCs (WT hiPSC-CMs) or isogenic hiPSCs deficient in the sarcomere protein cardiac myosin-binding protein C (MYBPC3-/- hiPSC-CMs), we show that the WT microtissues adapted to the mechanical environment with increased contraction force commensurate to matrix stiffness, whereas the MYBPC3-/- microtissues exhibited impaired force development kinetics regardless of matrix stiffness and deficient contraction force only when grown on matrices with high fibre stiffness. Under mechanical overload, the MYBPC3-/- microtissues had a higher degree of calcium transient abnormalities, and exhibited an accelerated decay of calcium dynamics as well as calcium desensitization, which accelerated when contracting against stiffer fibres. Our findings suggest that MYBPC3 deficiency and the presence of environmental stresses synergistically lead to contractile deficits in cardiac tissues
Stimulus Responsive Nanoparticles
Disclosed are various embodiments of methods and systems related to stimulus responsive nanoparticles. In one embodiment includes a stimulus responsive nanoparticle system, the system includes a first electrode, a second electrode, and a plurality of elongated electro-responsive nanoparticles dispersed between the first and second electrodes, the plurality of electro-responsive nanorods configured to respond to an electric field established between the first and second electrodes
Utility of Comorbidity Assessment in Predicting Transplantation-Related Toxicity Following Autologous Hematopoietic Stem Cell Transplantation for Multiple Myeloma
AbstractPatients with coexisting medical problems may suffer increased toxicity and reduced quality of life after autologous hematopoietic stem cell transplantation (HSCT). The benefit of high-dose therapy for some patients with multiple myeloma (MM) is debatable. Decision tools that aid in identifying those patients with MM most suited for autologous HSCT may avoid the risk of excess toxicity. An objective assessment of comorbidities was performed in 126 patients with MM undergoing autologous HSCT using the Charlson comorbidity index (CCI), the hematopoietic cell transplantation comorbidity index (HCT-CI), and a modified pretransplantation assessment of mortality (mPAM) to determine the strength of association with increased transplantation-related toxicity and increased length of hospital stay (LOS). Any comorbidity scored using the CCI or HCT-CI (score > 0) was associated with an increased number of organ systems with serious toxicity (at least grade 2 toxicity using the Seattle criteria), an increased total sum of toxicity grades for all organs, and prolonged LOS. An mPAM score ≥ 24 was associated with increased LOS. When considering autologous HSCT for a patient with MM, assessment of comorbidities using the CCI or HCT-CI may assist in predicting the risk of transplantation-related toxicity as an adjunct to physician judgment and patient preference
Polyelectrolyte multilayer formation: electrostatics and short-range interactions
We investigate the phenomenon of multilayer formation via layer-by-layer
deposition of alternating charge polyelectrolytes. Using mean-field theory, we
find that a strong short-range attraction between the two types of polymer
chains is essential for the formation of multilayers. The dependence of the
required short-range attraction on the polymer charge fraction and salt
concentration is calculated. For weak short-range attraction between any two
adjacent layers, the adsorbed amount (per added layer) decays as the distance
from the surface increases, until the chains stop adsorbing altogether. For
strong short-range attraction, the adsorbed amount per layer increases after an
initial decrease, and finally it stabilizes in the form of a polyelectrolyte
multilayer that can be repeated many times.Comment: 8 pages, 7 figure
Renormalisation and fixed points in Hilbert Space
The energies of low-lying bound states of a microscopic quantum many-body
system of particles can be worked out in a reduced Hilbert space. We present
here and test a specific non-perturbative truncation procedure. We also show
that real exceptional points which may be present in the spectrum can be
identified as fixed points of coupling constants in the truncation procedure.Comment: 4 pages, 1 tabl
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