Gingival Recession, Oral Hygiene and Associated Factors Among Tanzanian Women.

Females are generally more motivated with regard to oral hygiene practices and thus brush their teeth more frequently than males. To determine the prevalence of gingival recession, oral hygiene status, oral hygiene practices and associated factors in women attending a maternity ward in Tanzania. Cross-sectional descriptive study. Maternity ward of Muhimbili National Hospital, Tanzania. Four hundred and forty six women were interviewed on oral hygiene practices and maternal factors, and a full-mouth examination was done to determine the presence of plaque, calculus, gingival bleeding and gingival recession at six sites per tooth. The prevalence of gingival recession (GR) > or =1 mm was 33.6%, calculus 99.3%, plaque 100%, and gingival bleeding 100%. Oral hygiene practices included toothbrushing (98.9%), brushing frequency > or =2 times/day (61.2%), horizontal brushing method (98%), and using a plastic toothbrush (97.8%). Factors that were significantly associated with gingival recession were age (OR = 2.0, 95% CI = 1.3-3.2), presence of calculus (OR(a) = 3.8, 95% CI=2.5-7.1), and gingival bleeding on probing (OR = 4.2, 95% CI = 2.5-7.1). Tooth cleaning practices and maternal factors, especially the number of pregnancies or deliveries were not significantly associated with gingival recession. In this study population, oral hygiene was poor and gingival recession was associated with age, calculus and gingival inflammation rather than with tooth cleaning practices

An improved lower bound for (1,<=2)-identifying codes in the king grid

We call a subset $C$ of vertices of a graph $G$ a $(1,\leq \ell)$-identifying code if for all subsets $X$ of vertices with size at most $\ell$, the sets $\{c\in C |\exists u \in X, d(u,c)\leq 1\}$ are distinct. The concept of identifying codes was introduced in 1998 by Karpovsky, Chakrabarty and Levitin. Identifying codes have been studied in various grids. In particular, it has been shown that there exists a $(1,\leq 2)$-identifying code in the king grid with density 3/7 and that there are no such identifying codes with density smaller than 5/12. Using a suitable frame and a discharging procedure, we improve the lower bound by showing that any $(1,\leq 2)$-identifying code of the king grid has density at least 47/111

Ultimate periodicity of b-recognisable sets : a quasilinear procedure

It is decidable if a set of numbers, whose representation in a base b is a regular language, is ultimately periodic. This was established by Honkala in 1986. We give here a structural description of minimal automata that accept an ultimately periodic set of numbers. We then show that it can verified in linear time if a given minimal automaton meets this description. This thus yields a O(n log(n)) procedure for deciding whether a general deterministic automaton accepts an ultimately periodic set of numbers.Comment: presented at DLT 201

Spectroscopic link between adsorption site occupation and local surface chemical reactivity

In this Letter we show that sequences of adsorbate-induced shifts of surface core level (SCL) x-ray photoelectron spectra contain profound information on surface changes of electronic structure and reactivity. Energy shifts and intensity changes of time-lapsed spectral components follow simple rules, from which adsorption sites are directly determined. Theoretical calculations rationalize the results for transition metal surfaces in terms of the energy shift of the d-band center of mass and this proves that adsorbate-induced SCL shifts provide a spectroscopic measure of local surface reactivity

GINGIVAL RECESSION, ORAL HYGIENE AND ASSOCIATED FACTORS AMONG TANZANIAN WOMEN

Background: Females are generally more motivated with regard to oral hygiene practices andthus brush their teeth more frequently than males.Objective: To determine the prevalence of gingival recession, oral hygiene status, oral hygienepractices and associated factors in women attending a maternity ward in Tanzania.Design: Cross-sectional descriptive study.Setting: Maternity ward of Muhimbili National Hospital, Tanzania.Subjects: Four hundred and forty six women were interviewed on oral hygiene practicesand maternal factors, and a full-mouth examination was done to determine the presence ofplaque, calculus, gingival bleeding and gingival recession at six sites per tooth.Results: The prevalence of gingival recession (GR) &gt; 1mm was 33.6%, calculus 99.3%,plaque 100%, and gingival bleeding 100%. Oral hygiene practices included toothbrushing(98.9%), brushing frequency &gt;2 times/day (61.2%), horizontal brushing method (98%), andusing a plastic toothbrush (97.8%). Factors that were significantly associated with gingivalrecession were age (ORa=2.0, 95% CI=1.3-3.2), presence of calculus (ORa=3.8, 95% CI=2.5-7.1),and gingival bleeding on probing (ORa=4.2, 95% CI=2.5-7.1). Tooth cleaning practices andmaternal factors, especially the number of pregnancies or deliveries were not significantlyassociated with gingival recession.Conclusion: In this study population, oral hygiene was poor and gingival recession wasassociated with age, calculus and gingival inflammation rather than with tooth cleaningpractices

Enumeration and Decidable Properties of Automatic Sequences

We show that various aspects of k-automatic sequences -- such as having an unbordered factor of length n -- are both decidable and effectively enumerable. As a consequence it follows that many related sequences are either k-automatic or k-regular. These include many sequences previously studied in the literature, such as the recurrence function, the appearance function, and the repetitivity index. We also give some new characterizations of the class of k-regular sequences. Many results extend to other sequences defined in terms of Pisot numeration systems

Predicting Catalysis: Understanding Ammonia Synthesis from First-Principles Calculations

Here, we give a full account of a large collaborative effort toward an atomic-scale understanding of modern industrial ammonia production over ruthenium catalysts. We show that overall rates of ammonia production can be determined by applying various levels of theory (including transition state theory with or without tunneling corrections, and quantum dynamics) to a range of relevant elementary reaction steps, such as N2 dissociation, H2 dissociation, and hydrogenation of the intermediate reactants. A complete kinetic model based on the most relevant elementary steps can be established for any given point along an industrial reactor, and the kinetic results can be integrated over the catalyst bed to determine the industrial reactor yield. We find that, given the present uncertainties, the rate of ammonia production is well-determined directly from our atomic-scale calculations. Furthermore, our studies provide new insight into several related fields, for instance, gas-phase and electrochemical ammonia synthesis. The success of predicting the outcome of a catalytic reaction from first-principles calculations supports our point of view that, in the future, theory will be a fully integrated tool in the search for the next generation of catalysts.http://dx.doi.org/10.1021/jp056982

Weighted Coverings and Packings

In this paper we introduce a generalization of the concepts of coverings and packings in Hamming space called weighted coverings and packings. This allows us to formulate a number of well-known coding theoretical problems in a uniform manner. We study the existence of perfect weighted codes, discuss connections between weighted coverings and packings, and present many constructions for them