9,713 research outputs found
Continuous cell lysis in microfluidics through acoustic and optoelectronic tweezers
A versatile platform for efficient cell lysis using a combination of acoustic and
electric fields in a microchannel is presented. Cell membrane disruption is triggered by
electric fields inducing electroporation and then lysis. The principle of optoelectronic
tweezers (OET) is applied to control the electric field strength and a surface acoustic wave
transducer is attached to an OET chip to implement acoustic tweezing (AT). The system is
characterized in terms of spatial control of electric fields, single cell precision and lysi
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Presence of arthralgia exacerbates decreased quality of life in hidradenitis suppurativa patients
Hidradenitis suppurativa is characterized by chronic follicular occlusion that presents with recurrent nodules, inflamed abscesses, and scarring. Research has shown that these patients have a decreased quality of life. In addition to its psychosocial effects, hidradenitis suppurativa has recently been associated with joint pathology. In this study, we distributed a survey consisting of the Short Form 12 Health Survey, used for assessing health outcomes, along with additional questions about joint pain to an online hidradenitis suppurativa support group in order to understand the effect of comorbid arthralgia on quality of life in this disease. The respondents in this study had significantly reduced physical health composite scores-12 (PCS-12), (35.8 versus 50, P<0.001) and mental health composite scores-12 (MCS-12), (33.7 versus 50, P<0.001) scores compared to the general population. Additionally, patients reporting severe arthralgia had significantly lower PCS-12 (32.3 versus 36.5; P<0.05) and MCS-12 (33.3 versus 40.5; P<0.001) scores compared to those with mild arthralgia. Despite the effect of comorbid arthralgia on quality of life, only 11% reported having been asked about joint pain by their dermatologist. Routine screening questions concerning associated arthralgia and diminished quality of life may be helpful during clinician assessment and treatment of hidradenitis suppurativa patients
A multi-resolution model to capture both global fluctuations of an enzyme and molecular recognition in the ligand-binding site
In multi-resolution simulations, different system components are
simultaneously modelled at different levels of resolution, these being smoothly
coupled together. In the case of enzyme systems, computationally expensive
atomistic detail is needed in the active site to capture the chemistry of
substrate binding. Global properties of the rest of the protein also play an
essential role, determining the structure and fluctuations of the binding site;
however, these can be modelled on a coarser level. Similarly, in the most
computationally efficient scheme only the solvent hydrating the active site
requires atomistic detail. We present a methodology to couple atomistic and
coarse-grained protein models, while solvating the atomistic part of the
protein in atomistic water. This allows a free choice of which protein and
solvent degrees of freedom to include atomistically, without loss of accuracy
in the atomistic description. This multi-resolution methodology can
successfully model stable ligand binding, and we further confirm its validity
via an exploration of system properties relevant to enzymatic function. In
addition to a computational speedup, such an approach can allow the
identification of the essential degrees of freedom playing a role in a given
process, potentially yielding new insights into biomolecular function
Irreversible processes and the accelerated-decelerated phases of the Universe
A model for the Universe is proposed where it is considered as a mixture of
scalar and matter fields. The particle production is due to an irreversible
transfer of energy from the gravitational field to the matter field and
represented by a non-equilibrium pressure. This model can simulate three
distinct periods of the Universe: (a) an accelerated epoch where the energy
density of the scalar field prevails over the matter field, (b) a past
decelerated period where the energy density of the matter field becomes more
predominant than the scalar energy density, and (c) a present acceleration
phase where the scalar energy density overcomes the energy density of the
matter field.Comment: 6 pages, 2 figures, to be published in Brazilian Journal of Physic
Advantages and challenges in coupling an ideal gas to atomistic models in adaptive resolution simulations
In adaptive resolution simulations, molecular fluids are modeled employing
different levels of resolution in different subregions of the system. When
traveling from one region to the other, particles change their resolution on
the fly. One of the main advantages of such approaches is the computational
efficiency gained in the coarse-grained region. In this respect the best
coarse-grained system to employ in the low resolution region would be the ideal
gas, making intermolecular force calculations in the coarse-grained subdomain
redundant. In this case, however, a smooth coupling is challenging due to the
high energetic imbalance between typical liquids and a system of
non-interacting particles. In the present work, we investigate this approach,
using as a test case the most biologically relevant fluid, water. We
demonstrate that a successful coupling of water to the ideal gas can be
achieved with current adaptive resolution methods, and discuss the issues that
remain to be addressed
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