Instituting an Oral Health Preventive Service Program, Including Fluoride Varnish, for Preschool Children Birth to Five Years in a Rural Health Clinic: A clinical Scholarship Project

Abstract This project was designed to institute an oral health preventive program in a rural health clinic, in a dental provider shortage area, promoting oral health in preschool children birth to five years by: (a) instituting a program that supports the Missouri preventive service program in oral health, (b) promoting oral screenings and fluoride varnish twice yearly, (c) assessing the risk of caries, (d) referring to appropriate dental services and (e) educating parents or guardian about the importance of oral health and how to maintain oral health at home with children birth to five years. This project sought to answer the following questions: (1) Will children birth to five years in a rural health clinic have low, moderate, or high risk for caries? (2)Are there specific risk factors in children birth to five years in a rural health clinic that are more common in the high risk category for caries? (3) Is there a specific ethnic group in children birth to five years in rural health clinics that are at a higher risk for caries? (4) Are oral health educational materials an effective tool for the parents? Key findings were: The majority of the children 35 (97.2%) had never been seen by a dentist; 27 (75%) were in the High Risk category for early childhood cavities, 3 (8.3%) were found to have white spot lesions, the first sign of decay, 8 (22%) had evidence of rampant decay (seven or more cavities), 9 (25%) had untreated decay, 10 (27.8%) had evidence of early childhood cavities; urgent referral for extensive cavities was needed by 9 (25%) of the children, 6 (67%) were African American and Hispanic. There was insufficient time to evaluate if educational materials were an effective tool. Findings from this study clearly demonstrate that an oral health preventive service program, which includes the application of fluoride varnish, be a part of the well child exam and should begin earlier than school age children

Population Dynamics in the Penna Model

We build upon the recent steady-state Penna model solution, Phys.Rev.Lett. 89, 288103 (2002), to study the population dynamics within the Penna model. We show, that any perturbation to the population can be broken into a collection of modes each of which decay exponentially with its respective time constant. The long time behaviour of population is therefore likely to be dominated by the modes with the largest time constants. We confirm our analytical approach with simulation data.Comment: 6 figure

Natural Transfer of Viable Microbes in Space from Planets in the Extra-Solar Systems to a Planet in our Solar System and Vice-Versa

We investigate whether it is possible that viable microbes could have been transported to Earth from the planets in extra-solar systems by means of natural vehicles such as ejecta expelled by comet or asteroid impacts on such planets. The probabilities of close encounters with other solar systems are taken into account as well as the limitations of bacterial survival times inside ejecta in space, caused by radiation and DNA decay. The conclusion is that no potentially DNA/RNA life-carrying ejecta from another solar system in the general Galactic star field landed on Earth before life already existed on Earth, not even if microbial survival time in space is as long as tens of millions of years. However, if the Sun formed initially as a part of a star cluster, as is commonly assumed, we cannot rule out the possibility of transfer of life from one of the sister systems to us. Likewise, there is a possibility that some extra-solar planets carry life that originated in our solar system. It will be of great interest to identify the members of the Sun's birth cluster of stars and study them for evidence for planets and life on the planets. The former step may be accomplished by the GAIA mission, the latter step by the SIM and DARWIN missions. Therefore it may not be too long until we have experimental knowledge on the question whether the natural transfer of life from one solar system to another has actually taken place.Comment: 25 pages, 1 table, accepted to Ap

On associated polynomials and decay rates for birth-death processes

We consider sequences of orthogonal polynomials and pursue the question of how (partial) knowledge of the orthogonalizing measure for the {\it associated polynomials} can lead to information about the orthogonalizing measure for the original polynomials. In particular, we relate the supports of the two measures, and their moments. As an application we analyse the relation between two decay rates connected with a birth-death process. \u

The indeterminate rate problem for birth-death processes

A birth-death process is completely determined by its set of rates if and only if this set satisfies a certain condition C, say. If for a set of rates R the condition C is not fulfilled, then the problem arises of characterizing all birth-death processes which have rate set R (the indeterminate rate problem associated with R). We show that the characterization may be effected by means of the decay parameter, and we determine the set of possible values for the decay parameter in terms of JR. A fundamental role in our analysis is played by a duality concept for rate sets, which, if the pertinent rate sets satisfy C, obviously leads to a duality concept for birth-death processes. The latter can be stated in a form which suggests the possibility of extension in the context of indeterminate rate problems. This, however, is shown to be only partially true

Population synthesis of isolated Neutron Stars with magneto--rotational evolution

We revisit the population synthesis of isolated radio-pulsars incorporating recent advances on the evolution of the magnetic field and the angle between the magnetic and rotational axes from new simulations of the magneto-thermal evolution and magnetosphere models, respectively. An interesting novelty in our approach is that we do not assume the existence of a death line. We discuss regions in parameter space that are more consistent with the observational data. In particular, we find that any broad distribution of birth spin periods with $P_0\lesssim 0.5$ s can fit the data, and that if the alignment angle is allowed to vary consistently with the torque model, realistic magnetospheric models are favoured compared to models with classical magneto-dipolar radiation losses. Assuming that the initial magnetic field is given by a lognormal distribution, our optimal model has mean strength $\langle\log B_0{\rm [G]}\rangle \approx 13.0-13.2$ with width $\sigma (\log B_0) = 0.6-0.7$. However, there are strong correlations between parameters. This degeneracy in the parameter space can be broken by an independent estimate of the pulsar birth rate or by future studies correlating this information with the population in other observational bands (X-rays and $\gamma$-rays).Comment: 10 pages, 9 figures, submitted and accepted to MNRAS, comments welcom

The level and duration of RSV-specific maternal IgG in infants in Kilifi Kenya

Background Respiratory syncytial virus (RSV) is the major cause of lower respiratory tract infection in infants. The rate of decay of RSV-specific maternal antibodies (RSV-matAb), the factors affecting cord blood levels, and the relationship between these levels and protection from infection are poorly defined. Methods A birth cohort (n = 635) in rural Kenya, was studied intensively to monitor infections and describe age-related serological characteristics. RSV specific IgG antibody (Ab) in serum was measured by the enzyme linked immunosorbent assay (ELISA) in cord blood, consecutive samples taken 3 monthly, and in paired acute and convalescent samples. A linear regression model was used to calculate the rate of RSV-matAb decline. The effect of risk factors on cord blood titres was investigated. Results The half-life of matAb in the Kenyan cohort was calculated to be 79 days (95% confidence limits (CL): 76–81 days). Ninety seven percent of infants were born with RSV-matAb. Infants who subsequently experienced an infection in early life had significantly lower cord titres of anti-RSV Ab in comparison to infants who did not have any incident infection in the first 6 months (P = 0.011). RSV infections were shown to have no effect on the rate of decay of RSV-matAb. Conclusion Maternal-specific RSV Ab decline rapidly following birth. However, we provide evidence of protection against severe disease by RSV-matAb during the first 6–7 months. This suggests that boosting maternal-specific Ab by RSV vaccination may be a useful strategy to consider

Critical behavior and Griffiths effects in the disordered contact process

We study the nonequilibrium phase transition in the one-dimensional contact process with quenched spatial disorder by means of large-scale Monte-Carlo simulations for times up to $10^9$ and system sizes up to $10^7$ sites. In agreement with recent predictions of an infinite-randomness fixed point, our simulations demonstrate activated (exponential) dynamical scaling at the critical point. The critical behavior turns out to be universal, even for weak disorder. However, the approach to this asymptotic behavior is extremely slow, with crossover times of the order of $10^4$ or larger. In the Griffiths region between the clean and the dirty critical points, we find power-law dynamical behavior with continuously varying exponents. We discuss the generality of our findings and relate them to a broader theory of rare region effects at phase transitions with quenched disorder.Comment: 10 pages, 8 eps figures, final version as publishe

On the α-classification of birth-death and quasi-birth-death processes

In several recent papers criteria for the α-classification of birth-death and quasi-birth-death processes have been proposed. In this paper the relations between the various criteria are brought to light

Quasi-stationary distributions

This paper contains a survey of results related to quasi-stationary distributions, which arise in the setting of stochastic dynamical systems that eventually evanesce, and which may be useful in describing the long-term behaviour of such systems before evanescence. We are concerned mainly with continuous-time Markov chains over a finite or countably infinite state space, since these processes most often arise in applications, but will make reference to results for other processes where appropriate. Next to giving an historical account of the subject, we review the most important results on the existence and identification of quasi-stationary distributions for general Markov chains, and give special attention to birth-death processes and related models. Results on the question of whether a quasi-stationary distribution, given its existence, is indeed a good descriptor of the long-term behaviour of a system before evanescence, are reviewed as well. The paper is concluded with a summary of recent developments in numerical and approximation methods