8,317 research outputs found
Macroion adsorption: The crucial role of excluded volume and coions
The adsorption of charged colloids (macroions) onto an oppositely charged
planar substrate is investigated theoretically. Taking properly into account
the finite size of the macroions, unusual behaviors are reported. It is found
that the role of the coions (the little salt-ions carrying the same sign of
charge as that of the substrate) is crucial to understand the mechanisms
involved in the process of macroion adsorption. In particular, the coions can
accumulate near the substrate's surface and lead to a counter-intuitive {\it
surface charge amplification}.Comment: 11 pages - 4 figures. To appear in JC
An example of interplay between Physics and Mathematics: Exact resolution of a new class of Riccati Equations
A novel recipe for exactly solving in finite terms a class of special
differential Riccati equations is reported. Our procedure is entirely based on
a successful resolution strategy quite recently applied to quantum dynamical
time-dependent SU(2) problems. The general integral of exemplary differential
Riccati equations, not previously considered in the specialized literature, is
explicitly determined to illustrate both mathematical usefulness and easiness
of applicability of our proposed treatment. The possibility of exploiting the
general integral of a given differential Riccati equation to solve an SU(2)
quantum dynamical problem, is succinctly pointed out.Comment: 10 page
Behavioural interventions for weight management in pregnancy: A systematic review of quantitative and qualitative data
Objective: To assess the effectiveness of dietary with or without physical activity interventions to prevent excessive weight gain in pregnancy and explore the factors that influence intervention effectiveness.
Design: Systematic review, including a meta-analysis of controlled trials of interventions to prevent excessive weight gain during pregnancy and a thematic synthesis of qualitative studies that investigated the views of women on weight management during pregnancy.
Data sources: Eleven electronic bibliographic databases, reference list of included studies, relevant review articles and experts in the field.
Review methods: Two independent reviewers extracted data. RevMan software was used to perform the meta-analyses. Qualitative data was subject to thematic analysis. Both quantitative and qualitative data were aligned using a matrix framework.
Results: Five controlled trials and nine qualitative studies were included. The overall pooled effect size found no significant difference in gestational weight gain amongst participants in the interventions group compared with the control group (mean difference -1.88kg CI -4.34 to 0.59). The study designs, participants and interventions all varied markedly and there was significant heterogeneity within this comparison in the meta-analysis (I2 76%). Subgroup and sensitivity analysis did not identify contextual elements that influenced the effectiveness of the intervention.
In a thematic analysis of the qualitative studies, three major themes emerged relating to women’s views of weight management in pregnancy; pregnancy as a time of transition and change, conflicting and contradictory messages, a perceived lack of control. When the results of both quantitative and qualitative data were aligned it was clear that some of the barriers that women described in achieving healthy weight gain in pregnancy were not addressed by the interventions evaluated. This may have contributed to the limited effectiveness of the interventions.
Conclusions: Despite intense and often tailored interventions there was no statistically significant effect on weight gain during pregnancy. Inadequate and often contradictory information regarding healthy weight management was reported by women in qualitative studies and this was addressed in the interventions but in itself was insufficient to lead to reduced weight gain. Multiple types of interventions, including community based strategies, are needed to address this complex health problem
Definition of smolder experiments for Spacelab
The feasibility of conducting experiments in space on smoldering combustion was studied to conceptually design specific smoldering experiments to be conducted in the Shuttle/Spacelab System. Design information for identified experiment critical components is provided. The analytical and experimental basis for conducting research on smoldering phenomena in space was established. Physical descriptions of the various competing processes pertaining to smoldering combustion were identified. The need for space research was defined based on limitations of existing knowledge and limitations of ground-based reduced-gravity experimental facilities
Velocity Fields in Non--Gaussian Cold Dark Matter Models
We analyse the large--scale velocity field obtained by N--body simulations of
cold dark matter (CDM) models with non--Gaussian primordial density
fluctuations, considering models with both positive and negative primordial
skewness in the density fluctuation distribution. We study the velocity
probability distribution and calculate the dependence of the bulk flow,
one--point velocity dispersion and Cosmic Mach Number on the filtering size. We
find that the sign of the primordial skewness of the density field provides
poor discriminatory power on the evolved velocity field. All non--Gaussian
models here considered tend to have lower velocity dispersion and bulk flow
than the standard Gaussian CDM model, while the Cosmic Mach Number turns out to
be a poor statistic in characterizing the models. Next, we compare the
large--scale velocity field of a composite sample of optically selected
galaxies as described by the Local Group properties, bulk flow, velocity
correlation function and Cosmic Mach Number, with the velocity field of mock
catalogues extracted from the N--body simulations. The comparison does not
clearly permit to single out a best model: the standard Gaussian model is
however marginally preferred by the maximum likelihood analysis.Comment: 10 pages in Latex with mn.sty (available at the end of the paper
Interactions between arenavirus proteins and small molecule inhibitors of infection
Arenaviruses are globally distributed, negative-sense, single-stranded RNA viruses which persist in specific rodent host species. Of the 32 known arenaviruses, 10 have been associated with human disease. Of these, Lassa, JunĂn, Machupo, Guanarito, and Sabia viruses cause severe hemorrhagic fevers. The only current option for the treatment of arenavirus infection is the off-label use of ribavirin. However, ribavirin is associated with severe side effects. Clearly, there exists a need for the study of arenavirus biology and of novel drugs for the treatment of arenaviral infection. My work focused on two attractive targets for inhibition of infection: the arenaviral RNA-dependent RNA polymerase, to block replication of the viral genome, and the arenaviral envelope glycoprotein (GPC), to prevent delivery of the viral genome to the cytosol. We showed that the novel purine analogue, T-705, is effective at inhibiting the replication of highly pathogenic arenaviruses in vitro. Further, we showed that T-705 specifically blocks viral transcription without significantly reducing cellular transcription activity. We also explored the interactions between the SSP and G2 subunits within GPC. We demonstrated that the first transmembrane region of SSP is a functional subdomain and that the interactions between this region and the transmembrane region of G2 are essential to fusion activity. Further, we demonstrated that residues in this subdomain are key to drug sensitivity. We also worked to characterize the arrangement between the transmembrane regions using cysteine-scanning mutagenesis and we engineered a construct linking the first transmembrane region of SSP to the transmembrane region of G2 to serve as a potential model for studying the interactions between these two regions
Patterning molecular scale paramagnets at Au Surface: A root to Magneto-Molecular-Electronics
Few examples of the exploitation of molecular magnetic properties in
molecular electronics are known to date. Here we propose the realization of
Self assembled monolayers (SAM) of a particular stable organic radical. This
radical is meant to be used as a standard molecule on which to prove the
validity of a single spin reading procedure known as ESR-STM. We also discuss a
range of possible applications, further than ESR-STM, of magnetic monolayers of
simple purely organic magnetic molecule.Comment: This preprint is currently partially under revisio
- …