483 research outputs found
Twist-bend instability for toroidal DNA condensates
We propose that semiflexible polymers in poor solvent collapse in two stages.
The first stage is the well known formation of a dense toroidal aggregate.
However, if the solvent is sufficiently poor, the condensate will undergo a
second structural transition to a twisted entangled state, in which individual
filaments lower their bending energy by additionally orbiting around the mean
path along which they wind. This ``topological ripening'' is consistent with
known simulations and experimental results. It connects and rationalizes
various experimental observations ranging from strong DNA entanglement in viral
capsids to the unusually short pitch of the cholesteric phase of DNA in
sperm-heads. We propose that topological ripening of DNA toroids could improve
the efficiency and stability of gene delivery.Comment: 4 pages, 3 figures, RevTeX4 styl
The Osmotic Coefficient of Rod-like Polyelectrolytes: Computer Simulation, Analytical Theory, and Experiment
The osmotic coefficient of solutions of rod-like polyelectrolytes is
considered by comparing current theoretical treatments and simulations to
recent experimental data. The discussion is restricted to the case of
monovalent counterions and dilute, salt-free solutions. The classical
Poisson-Boltzmann solution of the cell model correctly predicts a strong
decrease in the osmotic coefficient, but upon closer look systematically
overestimates its value. The contribution of ion-ion-correlations are
quantitatively studied by MD simulations and the recently proposed DHHC theory.
However, our comparison with experimental data obtained on synthetic,
stiff-chain polyelectrolytes shows that correlation effects can only partly
explain the discrepancy. A quantitative understanding thus requires theoretical
efforts beyond the restricted primitive model of electrolytes.Comment: 16 pages, 2 figure
General Conceptual Framework of Future Wearables in Healthcare: Unified, Unique, Ubiquitous, and Unobtrusive (U4) for Customized Quantified Output
We concentrate on the importance and future conceptual development of wearable devices as the major means of personalized healthcare. We discuss and address the role of wearables in the new era of healthcare in proactive medicine. This work addresses the behavioral, environmental, physiological, and psychological parameters as the most effective domains in personalized healthcare, and the wearables are categorized according to the range of measurements. The importance of multi-parameter, multi-domain monitoring and the respective interactions are further discussed and the generation of wearables based on the number of monitoring area(s) is consequently formulated
A magnifying glass for the study of coupled developmental changes: Combining psychological networks and latent growth models
Effective field theory approach to Casimir interactions on soft matter surfaces
We utilize an effective field theory approach to calculate Casimir
interactions between objects bound to thermally fluctuating fluid surfaces or
interfaces. This approach circumvents the complicated constraints imposed by
such objects on the functional integration measure by reverting to a point
particle representation. To capture the finite size effects, we perturb the
Hamiltonian by DH that encapsulates the particles' response to external fields.
DH is systematically expanded in a series of terms, each of which scales
homogeneously in the two power counting parameters: \lambda \equiv R/r, the
ratio of the typical object size (R) to the typical distance between them (r),
and delta=kB T/k, where k is the modulus characterizing the surface energy. The
coefficients of the terms in DH correspond to generalized polarizabilities and
thus the formalism applies to rigid as well as deformable objects.
Singularities induced by the point particle description can be dealt with using
standard renormalization techniques. We first illustrate and verify our
approach by re-deriving known pair forces between circular objects bound to
films or membranes. To demonstrate its efficiency and versatility, we then
derive a number of new results: The triplet interactions present in these
systems, a higher order correction to the film interaction, and general scaling
laws for the leading order interaction valid for objects of arbitrary shape and
internal flexibility.Comment: 4 pages, 1 figur
Sufficient reliability of the behavioral and computational readouts of a probabilistic reversal learning task
Task-based measures that capture neurocognitive processes can help bridge the gap between brain and behavior. To transfer tasks to clinical application, reliability is a crucial benchmark because it imposes an upper bound to potential correlations with other variables (e.g., symptom or brain data). However, the reliability of many task readouts is low. In this study, we scrutinized the retest reliability of a probabilistic reversal learning task (PRLT) that is frequently used to characterize cognitive flexibility in psychiatric populations. We analyzed data from N = 40 healthy subjects, who completed the PRLT twice. We focused on how individual metrics are derived, i.e., whether data were partially pooled across participants and whether priors were used to inform estimates. We compared the reliability of the resulting indices across sessions, as well as the internal consistency of a selection of indices. We found good to excellent reliability for behavioral indices as derived from mixed-effects models that included data from both sessions. The internal consistency was good to excellent. For indices derived from computational modeling, we found excellent reliability when using hierarchical estimation with empirical priors and including data from both sessions. Our results indicate that the PRLT is well equipped to measure individual differences in cognitive flexibility in reinforcement learning. However, this depends heavily on hierarchical modeling of the longitudinal data (whether sessions are modeled separately or jointly), on estimation methods, and on the combination of parameters included in computational models. We discuss implications for the applicability of PRLT indices in psychiatric research and as diagnostic tools
Folding and insertion thermodynamics of the transmembrane WALP peptide
The anchor of most integral membrane proteins consists of one or several
helices spanning the lipid bilayer. The WALP peptide, GWW(LA)(L)WWA, is a
common model helix to study the fundamentals of protein insertion and folding,
as well as helix-helix association in the membrane. Its structural properties
have been illuminated in a large number of experimental and simulation studies.
In this combined coarse-grained and atomistic simulation study, we probe the
thermodynamics of a single WALP peptide, focusing on both the insertion across
the water-membrane interface, as well as folding in both water and a membrane.
The potential of mean force characterizing the peptide's insertion into the
membrane shows qualitatively similar behavior across peptides and three force
fields. However, the Martini force field exhibits a pronounced secondary
minimum for an adsorbed interfacial state, which may even become the global
minimum---in contrast to both atomistic simulations and the alternative PLUM
force field. Even though the two coarse-grained models reproduce the free
energy of insertion of individual amino acids side chains, they both
underestimate its corresponding value for the full peptide (as compared with
atomistic simulations), hinting at cooperative physics beyond the residue
level. Folding of WALP in the two environments indicates the helix as the most
stable structure, though with different relative stabilities and chain-length
dependence.Comment: 12 pages, 5 figure
Pengaruh Motivasi dan Kemampuan Serta Komitmen terhadap Kinerja Pengurus Upk PNPM Mandiri Perdesaan di Kabupaten Lumajang
This study aims to determine the influence of motivation and ability and commitment as well as simultaneous and partial view of the dominant of the Performance Management UPK PNPM Mandiri Rural In Lumajang of 60 respondents. The hypothesis in this study is the motivation and the ability and commitment to simultaneously have a significant effect on the performance committee UPK PNPM Mandiri Rural on Lumajang. Motivation and the ability and commitment partially significant effect on the performance committee UPK PNPM Mandiri Rural DistrictLumajang.Variabel motivation dominant influence on the performance committee UPK PNPM Mandiri Rural on Lumajang. The results of this study indicate: 1). Fcount value of 18.274 while the value of 2.769431 Ftable with probability = 0.000 when compared then Fcount > Ftable with α Ttable and a significance level of α β3> β2 thus dominant influence motivational variables on performance.This quantitative study provides an overview of the importance of motivation and the ability and commitment to improving employee performance. If the motivation and the ability and commitment to get less attention then it will be a decrease in employee performance
Unobtrusive Health Monitoring in Private Spaces: The Smart Vehicle
Unobtrusive in-vehicle health monitoring has the potential to use the driving time to perform regular medical check-ups. This work intends to provide a guide to currently proposed sensor systems for in-vehicle monitoring and to answer, in particular, the questions: (1) Which sensors are suitable for in-vehicle data collection? (2) Where should the sensors be placed? (3) Which biosignals or vital signs can be monitored in the vehicle? (4) Which purposes can be supported with the health data? We reviewed retrospective literature systematically and summarized the up-to-date research on leveraging sensor technology for unobtrusive in-vehicle health monitoring. PubMed, IEEE Xplore, and Scopus delivered 959 articles. We firstly screened titles and abstracts for relevance. Thereafter, we assessed the entire articles. Finally, 46 papers were included and analyzed. A guide is provided to the currently proposed sensor systems. Through this guide, potential sensor information can be derived from the biomedical data needed for respective purposes. The suggested locations for the corresponding sensors are also linked. Fifteen types of sensors were found. Driver-centered locations, such as steering wheel, car seat, and windscreen, are frequently used for mounting unobtrusive sensors, through which some typical biosignals like heart rate and respiration rate are measured. To date, most research focuses on sensor technology development, and most application-driven research aims at driving safety. Health-oriented research on the medical use of sensor-derived physiological parameters is still of interest
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