6,201 research outputs found
System-Size Effects on the Collective Dynamics of Cell Populations with Global Coupling
Phase-transitionlike behavior is found to occur in globally coupled systems
of finite number of elements, and its theoretical explanation is provided. The
system studied is a population of globally pulse-coupled integrate-and-fire
cells subject to small additive noise. As the population size is changed, the
system shows a phase-transitionlike behavior. That is, there exits a
well-defined critical system size above which the system stays in a monostable
state with high-frequency activity while below which a new phase characterized
by alternation of high- and low frequency activities appears. The mean field
motion obeys a stochastic process with state-dependent noise, and the above
phenomenon can be interpreted as a noise-induced transition characteristic to
such processes. Coexistence of high- and low frequency activities observed in
finite size systems is reported by N. Cohen, Y. Soen and E. Braun[Physica A249,
600 (1998)] in the experiments of cultivated heart cells. The present report
gives the first qualitative interpretation of their experimental results
Capsule-Based Dropwise Additive Manufacturing with Pharmaceutical Suspensions
Current manufacturing of pharmaceutical products focuses on creating a standard dosage of the active pharmaceutical ingredient (API); however, dosages often need to be altered or customized to account for a patient’s age, weight, comorbidity, and other genetic factors. A potential method for dispensing precise dosages of API suspensions through dropwise addition is detailed in the following paper. By using a drop-on-demand printing rig, a series of suspensions comprised of varying volume fractions of a micron-scale API in a carrier fluid were printed, and individual drop volumes were analyzed using high-resolution imaging. From this, capsules with 1 mg dosages and 100 mg dosages were manufactured. Completed trials yielded respective means of 1.043 mg and 99.946 mg of API being deposited across varying suspension compositions. The relative standard deviations of the 1 mg capsules averaged to be 1.51% and 0.30% for the 100 mg capsules. Further combinations of APIs and carrier fluids are continuing to be tested. The relative standard deviations of both dosage sizes are well under the 6% maximum variability imposed by the US Food and Drug Administration to regulate dosages of API, which provides evidence for the feasibility of printing pharmaceutical suspensions to create customized dosages for patient consumption
A Multi-signal Variant for the GPU-based Parallelization of Growing Self-Organizing Networks
Among the many possible approaches for the parallelization of self-organizing
networks, and in particular of growing self-organizing networks, perhaps the
most common one is producing an optimized, parallel implementation of the
standard sequential algorithms reported in the literature. In this paper we
explore an alternative approach, based on a new algorithm variant specifically
designed to match the features of the large-scale, fine-grained parallelism of
GPUs, in which multiple input signals are processed at once. Comparative tests
have been performed, using both parallel and sequential implementations of the
new algorithm variant, in particular for a growing self-organizing network that
reconstructs surfaces from point clouds. The experimental results show that
this approach allows harnessing in a more effective way the intrinsic
parallelism that the self-organizing networks algorithms seem intuitively to
suggest, obtaining better performances even with networks of smaller size.Comment: 17 page
Characterization of Knots and Links Arising From Site-specific Recombination on Twist Knots
We develop a model characterizing all possible knots and links arising from
recombination starting with a twist knot substrate, extending previous work of
Buck and Flapan. We show that all knot or link products fall into three
well-understood families of knots and links, and prove that given a positive
integer , the number of product knots and links with minimal crossing number
equal to grows proportionally to . In the (common) case of twist knot
substrates whose products have minimal crossing number one more than the
substrate, we prove that the types of products are tightly prescribed. Finally,
we give two simple examples to illustrate how this model can help determine
previously uncharacterized experimental data.Comment: 32 pages, 7 tables, 27 figures, revised: figures re-arranged, and
minor corrections. To appear in Journal of Physics
Methane activation and exchange by titanium-carbon multiple bonds
We demonstrate that a titanium-carbon multiple bond, specifically an alkylidyne ligand in the transient complex, (PNP)Ti≡C^(t)Bu (A) (PNP^− = N[2-P(CHMe_2)_(2)-4-methylphenyl]_2), can cleanly activate methane at room temperature with moderately elevated pressures to form (PNP)Ti=CHtBu(CH_3). Isotopic labeling and theoretical studies suggest that the alkylidene and methyl hydrogens exchange, either via tautomerization invoking a
methylidene complex, (PNP)Ti=CH_(2)(CH_(2)^(t)Bu), or by forming the methane adduct (PNP)Ti≡C^(t)Bu(CH_4). The thermal, fluxional and chemical behavior of (PNP)Ti=CH^(t)Bu(CH_3) is also presented in this study
Does religion make a difference? : assessing the effects of Christian affiliation and practice on marital solidarity and divorce in Britain, 1985-2005
Marital breakdown rates were examined among 15,714 adults from the British Social Attitudes dataset for 1985-2005. Separation and divorce peaked at around 50 years of age, and increased significantly over the period of study. Ratios of separation or divorce were compared between respondents who had no religious affiliation and (a) Christian affiliates who attended church at least once a month, (b) Christian affiliates who attended church, but less than once a month, and (c) Christian affiliates who never attended church. The results showed that active Christians were 1.5 times less likely to suffer marital breakdown than non-affiliates, but there was no difference between affiliates who never attended church and those of no religion. Christians who attended infrequently were 1.3 times less likely to suffer marital breakdown compared to non-affiliates, suggesting that even infrequent attendance at church may have some significance for predicting the persistence of martial solidarity
Physical demand but not dexterity is associated with motor flexibility during rapid reaching in healthy young adults
Healthy humans are able to place light and heavy objects in small and large target locations with remarkable accuracy. Here we examine how dexterity demand and physical demand affect flexibility in joint coordination and end-effector kinematics when healthy young adults perform an upper extremity reaching task. We manipulated dexterity demand by changing target size and physical demand by increasing external resistance to reaching. Uncontrolled manifold analysis was used to decompose variability in joint coordination patterns into variability stabilizing the end-effector and variability de-stabilizing the end-effector during reaching. Our results demonstrate a proportional increase in stabilizing and de-stabilizing variability without a change in the ratio of the two variability components as physical demands increase. We interpret this finding in the context of previous studies showing that sensorimotor noise increases with increasing physical demands. We propose that the larger de-stabilizing variability as a function of physical demand originated from larger sensorimotor noise in the neuromuscular system. The larger stabilizing variability with larger physical demands is a strategy employed by the neuromuscular system to counter the de-stabilizing variability so that performance stability is maintained. Our findings have practical implications for improving the effectiveness of movement therapy in a wide range of patient groups, maintaining upper extremity function in old adults, and for maximizing athletic performance
Space construction system analysis. Part 2: Construction analysis
The construction methods specific to the end to end construction process for building the ETVP in low Earth orbit, using the space shuttle orbiter as a construction base, are analyzed. The analyses concerned three missions required to build the basic platform. The first mission involved performing the fabrication of beams in space and assembling the beams into a basic structural framework. The second mission was to install the forward support structure and aft support structure, the forward assembly, and a TT&C antenna. The third mission plan was to complete the construction of the platform and activate it to begin operations in low Earth orbit. The integration of the activities for each mission is described along with the construction requirements and construction logic
Calculations of the Exclusive Processes 2H(e,e'p)n, 3He(e,e'p)2H and 3He(e,e'p)(pn) within a Generalized Glauber Approach
The exclusive processes 2H(e,e'p)n, 3He(e,e'p)2H and 3He(e,e'p)(pn), have
been analyzed using realistic few-body wave functions and treating the final
state interaction (FSI) within a Generalized Eikonal Approximation (GEA), based
upon the direct calculation of the Feynman diagrams describing the rescattering
of the struck nucleon with the nucleons of the A-1 system. The approach
represents an improvement of the conventional Glauber approach (GA), in that it
allows one to take into account the effects of the nuclear excitation of the
system on the rescattering of the struck nucleon. Using realistic
three-body wave functions corresponding to the AV18 interaction, the results of
our parameter free calculations are compared with available experimental data.
It is found that in some kinematical conditions FSI effects represent small
corrections, whereas in other kinematics conditions they are very large and
absolutely necessary to provide a satisfactory agreement between theoretical
calculations and experimental data. It is shown that in the kinematics of the
experimental data which have been considered, covering the region of missing
momentum and energy with p_m < 0.6 GeV/c and E_m < 100 MeV in the perpendicular
kinematics, the GA and GEA predictions differ only by less than 3-4 %.Comment: Typos detected and removed while Proof reading. Physical Review C. in
Pres
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