1,240 research outputs found
Stokes phenomenon and matched asymptotic expansions
This paper describes the use of matched asymptotic expansions to illuminate the description of functions exhibiting Stokes phenomenon. In particular the approach highlights the way in which the local structure and the possibility of finding Stokes multipliers explicitly depend on the behaviour of the coefficients of the relevant asymptotic expansions
Anharmonic molecular mechanics: Ab initio based Morse parameterisations for the popular MM3 force field
Methodologies for creating reactive potential energy surfaces from molecular
mechanics force-fields are becoming increasingly popular. To date, molecular
mechanics force-fields use harmonic expressions to treat bonding stretches,
which is a poor approximation in reactive molecular dynamics simulations since
bonds are displaced significantly from their equilibrium positions. For such
applications there is need for a better treatment of anharmonicity. In this
contribution Morse bonding potentials have been extensively parameterised for
the atom types in the MM3 force field of Allinger and co-workers using high
level CCSD(T)(F12*) energies. To our knowledge this is the first instance of a
large-scale paramerization of Morse potentials in a popular force field
The SISO CSPI PDG standard for commercial off-the-shelf simulation package interoperability reference models
For many years discrete-event simulation has been used to analyze production and logistics problems in manufactur-ing and defense. Commercial-off-the-shelf Simulation Packages (CSPs), visual interactive modelling environ-ments such as Arena, Anylogic, Flexsim, Simul8, Witness, etc., support the development, experimentation and visua-lization of simulation models. There have been various attempts to create distributed simulations with these CSPs and their tools, some with the High Level Architecture (HLA). These are complex and it is quite difficult to assess how a set of models/CSP are actually interoperating. As the first in a series of standards aimed at standardizing how the HLA is used to support CSP distributed simula-tions, the Simulation Interoperability Standards Organiza-tion’s (SISO) CSP Interoperability Product Development Group (CSPI PDG) has developed and standardized a set of Interoperability Reference Models (IRM) that are in-tended to clearly identify the interoperability capabilities of CSP distributed simulations
Asymptotics of near-cloaking
This paper describes how asymptotic analysis can be used to gain new insights into the theory of cloaking of spherical and cylindrical targets within the context of acoustic waves in a class of linear elastic materials. In certain cases these configurations allow solutions to be written down in terms of eigenfunction expansions from which high-frequency asymptotics can be extracted systematically. These asymptotics are compared with the predictions of ray theory and are used to describe the scattering that occurs when perfect cloaking models are regularised
Problem gambling: a suitable case for social work?
Problem gambling attracts little attention from health and social care agencies
in the UK. Prevalence surveys suggest that 0.6% of the population are
problem gamblers and it is suggested that for each of these individuals,
10–17 other people, including children and other family members, are
affected. Problem gambling is linked to many individual and social problems
including: depression, suicide, significant debt, bankruptcy, family conflict,
domestic violence, neglect and maltreatment of children and offending.
This makes the issue central to social work territory. Yet, the training of
social workers in the UK has consistently neglected issues of addictive
behaviour. Whilst some attention has been paid in recent years to substance
abuse issues, there has remained a silence in relation to gambling
problems. Social workers provide more help for problems relating to addictions
than other helping professions. There is good evidence that treatment,
and early intervention for gambling problems, including psycho-social and
public health approaches, can be very effective. This paper argues that
problem gambling should be moved onto the radar of the social work profession,
via inclusion on qualifying and post-qualifying training programmes
and via research and dissemination of good practice via institutions such as
the Social Care Institute for Excellence (SCIE).
Keywords: problem gambling; addictive behaviour; socia
Systematic evaluation of an atomic clock at 2e-18 total uncertainty
The pursuit of better atomic clocks has advanced many research areas,
providing better quantum state control, new insights in quantum science,
tighter limits on fundamental constant variation, and improved tests of
relativity. The record for the best stability and accuracy is currently held by
optical lattice clocks. This work takes an important step towards realizing the
full potential of a many-particle clock with a state-of-the-art stable laser.
Our 87Sr optical lattice clock now achieves fractional stability of 2.2e-16 at
1 s. With this improved stability, we perform a new accuracy evaluation of our
clock, reducing many systematic uncertainties that limited our previous
measurements, such as those in the lattice ac Stark shift, the atoms' thermal
environment, and the atomic response to room-temperature BBR. Our combined
measurements have reduced the total uncertainty of the JILA Sr clock to 2.1e-18
in fractional frequency units.Comment: Full published versio
The effects of periodontal therapy on serum antibody (IgG) levels to plaque microorganisms *
The influence of periodontal therapy on serum antibody titers to selected periodontal disease-associated microorganisms was assessed in 23 patients having chronic inflammatory periodontal disease (CIPD), The immunoglobulin G (IgG) titers were dÉtÉrmined by the micro ELISA technique in serum samples obtained prior to treatment; following a hygienic phase which included scaling, root planing, and oral hygiene instruction; following surgical treatment; and one year and two years following hygienic phase (maintenance phase). Considerable individual variability existed in the magnitude of immune response to specific bacterial preparations. Significant reductions in the mean antibody titers were seen to A. viscosus. S. sanguis. F. nucleatum, S, spuligena, B. gingivalis. B. interme-dius. B. melaninogeniem, T. vincentii , and T denticola by the end of the second year of maintenance. There was no consistent response to Capnucytophaga. When individual patient responses were examined. 6 of the 23 were found to have elevated titers to at least one of the microorganisms in the interval between pretreatment and the end of the hygienic phase; however, in all but one case, the titers at the end of the second year of maintenance were below pretreatment levels. Antibody levels to bacteria such as S. sanguis were modified during therapy. This would indicate that immune responses to microbes not generally considered to be “periodontal pathogens” may be modified by adjuvant activity associated with subgingival plaque or changes in the environment of the sulcus and that subsequent changes in titer do not necessarily reflect a role of that microorganism in the disease process.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/75110/1/j.1600-051X.1988.tb02127.x.pd
The Microbiome in Bronchial Biopsies from Smokers and Ex-Smokers with Stable COPD - A Metatranscriptomic Approach
Current knowledge about the respiratory microbiome is mainly based on 16S ribosomal RNA gene sequencing. Newer sequencing approaches, such as metatranscriptomics, offer the technical ability to measure the viable microbiome response to environmental conditions such as smoking as well as to explore its functional role by investigating host-microbiome interactions. However, knowledge about its feasibility in respiratory microbiome research, especially in lung biopsies, is still very limited. RNA sequencing was performed in bronchial biopsies from clinically stable smokers (n=5) and ex-smokers (n=6) with COPD not using (inhaled) steroids. The Trinity assembler was used to assemble non-human reads in order to allow unbiased taxonomical and microbial transcriptional analyses. Subsequently, host-microbiome interactions were analyzed based on associations with host transcriptomic data. Ultra-low levels of microbial mass (0.009%) were identified in the RNA-seq data. Overall, no differences were identified in microbiome diversity or transcriptional profiles of microbial communities or individual microbes between COPD smokers and ex-smokers in the initial test dataset as well as a larger replication dataset. We identified an upregulated host gene set, related to the simultaneous presence of Bradyrhizobium, Roseomonas, Brevibacterium.spp., which were related to PERK-mediated unfolded protein response (UPR) and expression of the microRNA-155-5p. Our results show that metatranscriptomic profiling in bronchial biopsy samples from stable COPD patients yields ultra-low levels of microbial mass. Further, this study illustrates the potential of using transcriptional profiling of the host and microbiome to gain more insight into their interaction in the airways
Toward Predicting Success and Failure in CS2: A Mixed-Method Analysis
Factors driving success and failure in CS1 are the subject of much study but
less so for CS2. This paper investigates the transition from CS1 to CS2 in
search of leading indicators of success in CS2. Both CS1 and CS2 at the
University of North Carolina Wilmington (UNCW) are taught in Python with annual
enrollments of 300 and 150 respectively. In this paper, we report on the
following research questions: 1) Are CS1 grades indicators of CS2 grades? 2)
Does a quantitative relationship exist between CS2 course grade and a modified
version of the SCS1 concept inventory? 3) What are the most challenging aspects
of CS2, and how well does CS1 prepare students for CS2 from the student's
perspective? We provide a quantitative analysis of 2300 CS1 and CS2 course
grades from 2013--2019. In Spring 2019, we administered a modified version of
the SCS1 concept inventory to 44 students in the first week of CS2. Further, 69
students completed an exit questionnaire at the conclusion of CS2 to gain
qualitative student feedback on their challenges in CS2 and on how well CS1
prepared them for CS2. We find that 56% of students' grades were lower in CS2
than CS1, 18% improved their grades, and 26% earned the same grade. Of the
changes, 62% were within one grade point. We find a statistically significant
correlation between the modified SCS1 score and CS2 grade points. Students
identify linked lists and class/object concepts among the most challenging.
Student feedback on CS2 challenges and the adequacy of their CS1 preparations
identify possible avenues for improving the CS1-CS2 transition.Comment: The definitive Version of Record was published in 2020 ACM Southeast
Conference (ACMSE 2020), April 2-4, 2020, Tampa, FL, USA. 8 page
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