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Printing High Viscosity Fluids using Ultrasonic Droplet Generation
A new printing technology based on ultrasonic actuation (~1 MHz) is presented that has the
potential to print high viscosity fluids. In this paper, we describe the print-head’s operating
principles and construction. Acoustic focusing in the nozzles produces high pressure gradients
that help eject the fluid which, under the proper conditions, forms droplets. Two types of models
are presented to attempt to predict print-head behavior over a range of conditions. The first
model borrows from simple fully developed, laminar flows to estimate printing conditions based
on fluid properties, as well as printing pressures. The second model captures the dynamic
behavior of the print-head to estimate cavity resonances that lead to acoustic focusing and
potentially droplet generation. We report on experiments with several types of fluids that
demonstrate the technology’s potential.Mechanical Engineerin
The Universe as a Nonuniform Lattice in the Finite-Dimensional Hypercube II.Simple Cases of Symmetry Breakdown and Restoration
This paper continues a study of field theories specified for the nonuniform
lattice in the finite-dimensional hypercube with the use of the earlier
described deformation parameters. The paper is devoted to spontaneous breakdown
and restoration of symmetry in simple quantum-field theories with scalar
fields. It is demonstrated that an appropriate deformation opens up new
possibilities for symmetry breakdown and restoration. To illustrate, at low
energies it offers high-accuracy reproducibility of the same results as with a
nondeformed theory. In case of transition from low to higher energies and vice
versa it gives description for new types of symmetry breakdown and restoration
depending on the rate of the deformation parameter variation in time, and
indicates the critical points of the previously described lattice associated
with a symmetry restoration. Besides, such a deformation enables one to find
important constraints on the initial model parameters having an explicit
physical meaning.Comment: 9 pages,Revte
Chow's theorem and universal holonomic quantum computation
A theorem from control theory relating the Lie algebra generated by vector
fields on a manifold to the controllability of the dynamical system is shown to
apply to Holonomic Quantum Computation. Conditions for deriving the holonomy
algebra are presented by taking covariant derivatives of the curvature
associated to a non-Abelian gauge connection. When applied to the Optical
Holonomic Computer, these conditions determine that the holonomy group of the
two-qubit interaction model contains . In particular, a
universal two-qubit logic gate is attainable for this model.Comment: 13 page
Residence Time Statistics for Normal and Fractional Diffusion in a Force Field
We investigate statistics of occupation times for an over-damped Brownian
particle in an external force field. A backward Fokker-Planck equation
introduced by
Majumdar and Comtet describing the distribution of occupation times is
solved. The solution gives a general relation between occupation time
statistics and probability currents which are found from solutions of the
corresponding problem of first passage time. This general relationship between
occupation times and first passage times, is valid for normal Markovian
diffusion and for non-Markovian sub-diffusion, the latter modeled using the
fractional Fokker-Planck equation. For binding potential fields we find in the
long time limit ergodic behavior for normal diffusion, while for the fractional
framework weak ergodicity breaking is found, in agreement with previous results
of Bel and Barkai on the continuous time random walk on a lattice. For
non-binding potential rich physical behaviors are obtained, and classification
of occupation time statistics is made possible according to whether or not the
underlying random walk is recurrent and the averaged first return time to the
origin is finite. Our work establishes a link between fractional calculus and
ergodicity breaking.Comment: 12 page
Molecular bases determining daptomycin resistance-mediated re-sensitization to β-lactams ("see-saw effect") in MRSA
Antimicrobial resistance is recognized as one of the principal threats to public health worldwide, yet the problem is increasing. Methicillin-resistant Staphylococcus aureus (MRSA) are among the most difficult to treat in clinical settings due to the resistance to nearly all available antibiotics. The cyclic anionic lipopeptide antibiotic Daptomycin (DAP) is the clinical mainstay of anti-MRSA therapy. Decreased susceptibility to DAP (DAPR) reported in MRSA is frequently accompanied with a paradoxical decrease in β-lactam resistance, a process known as the "see-saw" effect. Despite the observed discordance in resistance phenotypes, the combination of DAP/β-lactams has been proven clinically effective for the prevention and treatment of infections due to DAPR-MRSA strains. However, the mechanisms underlying the interactions between DAP and β-lactams are largely unknown. Herein, we studied the role of DAP-induced mutated mprF in β-lactam sensitization and its involvement in the effective killing by the DAP/OXA combination. DAP/OXA-mediated effects resulted in cell-wall perturbations including changes in peptidoglycan (PG) insertion, penicillin-binding protein 2 (PBP2) delocalization and reduced membrane amounts of penicillin-binding protein 2a (PBP2a) contents despite increased transcription of mecA through mec regulatory elements. We have found that the VraSR sensor-regulator is a key component of DAP resistance, triggering mutated mprF-mediated cell membrane (CM) modifications and resulting in impairment of PrsA location and chaperone functions, both essentials for PBP2a maturation, the key determinant of β-lactam resistance. These observations provide first time evidence that synergistic effects between DAP and β-lactams involve PrsA post-transcriptional regulation of CM-associated PBP2a
Generalized Arcsine Law and Stable Law in an Infinite Measure Dynamical System
Limit theorems for the time average of some observation functions in an
infinite measure dynamical system are studied. It is known that intermittent
phenomena, such as the Rayleigh-Benard convection and Belousov-Zhabotinsky
reaction, are described by infinite measure dynamical systems.We show that the
time average of the observation function which is not the function,
whose average with respect to the invariant measure is finite, converges to
the generalized arcsine distribution. This result leads to the novel view that
the correlation function is intrinsically random and does not decay. Moreover,
it is also numerically shown that the time average of the observation function
converges to the stable distribution when the observation function has the
infinite mean.Comment: 8 pages, 8 figure
Weakly non-ergodic Statistical Physics
We find a general formula for the distribution of time averaged observables
for weakly non-ergodic systems. Such type of ergodicity breaking is known to
describe certain systems which exhibit anomalous fluctuations, e.g. blinking
quantum dots and the sub-diffusive continuous time random walk model. When the
fluctuations become normal we recover usual ergodic statistical mechanics.
Examples of a particle undergoing fractional dynamics in a binding force field
are worked out in detail. We briefly discuss possible physical applications in
single particle experiments
The melanoma-specific graded prognostic assessment does not adequately discriminate prognosis in a modern population with brain metastases from malignant melanoma
The melanoma-specific graded prognostic assessment (msGPA) assigns patients with brain metastases from malignant melanoma to 1 of 4 prognostic groups. It was largely derived using clinical data from patients treated in the era that preceded the development of newer therapies such as BRAF, MEK and immune checkpoint inhibitors. Therefore, its current relevance to patients diagnosed with brain metastases from malignant melanoma is unclear. This study is an external validation of the msGPA in two temporally distinct British populations.Performance of the msGPA was assessed in Cohort I (1997-2008, n=231) and Cohort II (2008-2013, n=162) using Kaplan-Meier methods and Harrell's c-index of concordance. Cox regression was used to explore additional factors that may have prognostic relevance.The msGPA does not perform well as a prognostic score outside of the derivation cohort, with suboptimal statistical calibration and discrimination, particularly in those patients with an intermediate prognosis. Extra-cerebral metastases, leptomeningeal disease, age and potential use of novel targeted agents after brain metastases are diagnosed, should be incorporated into future prognostic models.An improved prognostic score is required to underpin high-quality randomised controlled trials in an area with a wide disparity in clinical care
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