93 research outputs found
Setting and analysis of the multi-configuration time-dependent Hartree-Fock equations
In this paper we motivate, formulate and analyze the Multi-Configuration
Time-Dependent Hartree-Fock (MCTDHF) equations for molecular systems under
Coulomb interaction. They consist in approximating the N-particle Schrodinger
wavefunction by a (time-dependent) linear combination of (time-dependent)
Slater determinants. The equations of motion express as a system of ordinary
differential equations for the expansion coefficients coupled to nonlinear
Schrodinger-type equations for mono-electronic wavefunctions. The invertibility
of the one-body density matrix (full-rank hypothesis) plays a crucial role in
the analysis. Under the full-rank assumption a fiber bundle structure shows up
and produces unitary equivalence between convenient representations of the
equations. We discuss and establish existence and uniqueness of maximal
solutions to the Cauchy problem in the energy space as long as the density
matrix is not singular. A sufficient condition in terms of the energy of the
initial data ensuring the global-in-time invertibility is provided (first
result in this direction). Regularizing the density matrix breaks down energy
conservation, however a global well-posedness for this system in L^2 is
obtained with Strichartz estimates. Eventually solutions to this regularized
system are shown to converge to the original one on the time interval when the
density matrix is invertible.Comment: 48 pages, 1 figur
In vitro phosphorylation as tool for modification of silk and keratin fibrous materials
An overview is given of the recent work on in vitro enzymatic phosphorylation of silk fibroin and human hair keratin. Opposing to many chemical "conventional" approaches, enzymatic phosphorylation is in fact a mild reaction and the treatment falls within "green chemistry" approach. Silk and keratin are not phosphorylated in vivo, but in vitro. This enzyme-driven modification is a major technological breakthrough. Harsh chemical chemicals are avoided, and mild conditions make enzymatic phosphorylation a real "green chemistry" approach. The current communication presents a novel approach stating that enzyme phosphorylation may be used as a tool to modify the surface charge of biocompatible materials such as keratin and silk
Salivary Gland NK Cells Are Phenotypically and Functionally Unique
Natural killer (NK) cells and CD8+ T cells play vital roles in containing and eliminating systemic cytomegalovirus (CMV). However, CMV has a tropism for the salivary gland acinar epithelial cells and persists in this organ for several weeks after primary infection. Here we characterize a distinct NK cell population that resides in the salivary gland, uncommon to any described to date, expressing both mature and immature NK cell markers. Using RORγt reporter mice and nude mice, we also show that the salivary gland NK cells are not lymphoid tissue inducer NK-like cells and are not thymic derived. During the course of murine cytomegalovirus (MCMV) infection, we found that salivary gland NK cells detect the infection and acquire activation markers, but have limited capacity to produce IFN-γ and degranulate. Salivary gland NK cell effector functions are not regulated by iNKT or Treg cells, which are mostly absent in the salivary gland. Additionally, we demonstrate that peripheral NK cells are not recruited to this organ even after the systemic infection has been controlled. Altogether, these results indicate that viral persistence and latency in the salivary glands may be due in part to the presence of unfit NK cells and the lack of recruitment of peripheral NK cells
Efficient and accurate modeling of electron photoemission in nanostructures with TDDFT
We derive and extend the time-dependent surface-flux method introduced in [L. Tao, A. Scrinzi, New J. Phys. 14, 013021 (2012)] within a time-dependent density-functional theory (TDDFT) formalism and use it to calculate photoelectron spectra and angular distributions of atoms and molecules when excited by laser pulses. We present other, existing computational TDDFT methods that are suitable for the calculation of electron emission in compact spatial regions, and compare their results. We illustrate the performance of the new method by simulating strong-field ionization of C60 fullerene and discuss final state effects in the orbital reconstruction of planar organic molecules
A Measure of the Promiscuity of Proteins and Characteristics of Residues in the Vicinity of the Catalytic Site That Regulate Promiscuity
Promiscuity, the basis for the evolution of new functions through ‘tinkering’ of residues in the vicinity of the catalytic site, is yet to be quantitatively defined. We present a computational method Promiscuity Indices Estimator (PROMISE) - based on signatures derived from the spatial and electrostatic properties of the catalytic residues, to estimate the promiscuity (PromIndex) of proteins with known active site residues and 3D structure. PromIndex reflects the number of different active site signatures that have congruent matches in close proximity of its native catalytic site, the quality of the matches and difference in the enzymatic activity. Promiscuity in proteins is observed to follow a lognormal distribution (μ = 0.28, σ = 1.1 reduced chi-square = 3.0E-5). The PROMISE predicted promiscuous functions in any protein can serve as the starting point for directed evolution experiments. PROMISE ranks carboxypeptidase A and ribonuclease A amongst the more promiscuous proteins. We have also investigated the properties of the residues in the vicinity of the catalytic site that regulates its promiscuity. Linear regression establishes a weak correlation (R2∼0.1) between certain properties of the residues (charge, polar, etc) in the neighborhood of the catalytic residues and PromIndex. A stronger relationship states that most proteins with high promiscuity have high percentages of charged and polar residues within a radius of 3 Å of the catalytic site, which is validated using one-tailed hypothesis tests (P-values∼0.05). Since it is known that these characteristics are key factors in catalysis, their relationship with the promiscuity index cross validates the methodology of PROMISE
Balancing, Proportionality, and Constitutional Rights
In the theory and practice of constitutional adjudication, proportionality review plays a crucial role. At a theoretical level, it lies at core of the debate on rights adjudication; in judicial practice, it is a widespread decision-making model characterizing the action of constitutional, supra-national and international courts. Despite its circulation and centrality in contemporary legal discourse, proportionality in rights-adjudication is still extremely controversial. It raises normative questions—concerning its justification and limits—and descriptive questions—regarding its nature and distinctive features. The chapter addresses both orders of questions.
Part I centres on the justification of proportionality review, the connection between proportionality, balancing and theories of rights and the critical aspects of this connection.
Part II identifies and analyses the different forms of proportionality both in review, as a template for rights-adjudication, and of review, as a way of defining the scope and limits of adjudication
Washing our hands of the congenital cytomegalovirus disease epidemic
BACKGROUND: Each year in the United States, an estimated 40,000 children are born with congenital cytomegalovirus (CMV) infection, causing an estimated 400 deaths and leaving approximately 8000 children with permanent disabilities such as hearing or vision loss, or mental retardation. More children are affected by serious CMV-related disabilities than by several better-known childhood maladies, including Down syndrome, fetal alcohol syndrome, and spina bifida. DISCUSSION: Congenital CMV is a prime target for prevention not only because of its substantial disease burden but also because the biology and epidemiology of CMV suggest that there are ways to reduce viral transmission. Because exposure to the saliva or urine of young children is a major cause of CMV infection among pregnant women, it is likely that good personal hygiene, especially hand-washing, can reduce the risk of CMV acquisition. Experts agree that such measures are likely to be efficacious (i.e., they will work if consistently followed) and the American College of Obstetricians and Gynecologists recommends that physicians counsel pregnant women about preventing CMV acquisition through careful attention to hygiene. However, because of concerns about effectiveness (i.e., Will women consistently follow hygienic practices as the result of interventions?), the medical and public health communities appear reluctant to embrace primary CMV prevention via improved hygienic practices, and educational interventions are rare. Current data on the effectiveness of such measures in preventing CMV infection are promising, but limited. There is strong evidence, however, that educational interventions can prevent other infectious diseases with similar transmission modes, suggesting that effective interventions can also be found for CMV. Until a CMV vaccine becomes available, effective educational interventions are needed to inform women about congenital CMV prevention. SUMMARY: Perhaps no single cause of birth defects and developmental disabilities in the United States currently provides greater opportunity for improved outcomes in more children than congenital CMV. Given the present state of knowledge, women deserve to be informed about how they can reduce their risk of CMV infection during pregnancy, and trials are needed to identify effective educational interventions
Ab initio Electron Dynamics with the Multi-Configuration Time-Dependent Hartree-Fock Method
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