Optimal growth trajectories with finite carrying capacity.

We consider the problem of finding optimal strategies that maximize the average growth rate of multiplicative stochastic processes. For a geometric Brownian motion, the problem is solved through the so-called Kelly criterion, according to which the optimal growth rate is achieved by investing a constant given fraction of resources at any step of the dynamics. We generalize these finding to the case of dynamical equations with finite carrying capacity, which can find applications in biology, mathematical ecology, and finance. We formulate the problem in terms of a stochastic process with multiplicative noise and a nonlinear drift term that is determined by the specific functional form of carrying capacity. We solve the stochastic equation for two classes of carrying capacity functions (power laws and logarithmic), and in both cases we compute the optimal trajectories of the control parameter. We further test the validity of our analytical results using numerical simulations.

Assessment of humoral and cell-mediated immunity against Bordetella pertussis in adolescent, adult, and senior subjects in Italy.

Humoral and cell-mediated immunity (CMI) against B. pertussis was assessed in a sample of adolescent, adult and senior subjects distributed in five different geographical areas in Italy. Most (99.1%) subjects had IgG anti-pertussis toxin (PT) antibodies exceeding the minimum detection level [> or = 2 ELISA units (EU)/ml]. There were no significant differences between the genders; 6.2% samples recorded titres > or = 100 EU/ml. CMI was positive [stimulation index (SI) > or = 5] against PT in 39.0% of all samples. This study suggests that B. pertussis continues to circulate in age groups that have been previously considered to be uninvolved in the circulation of this pathogen and that adolescent and adult pertussis boosters may be of value in these populations. Nevertheless, over the last 10 years, large increases in vaccination coverage rates have contributed to reduce the spread of the aetiological agent, especially in the immunized population.

Study on hepatitis B and C serologic status among municipal solid waste workers in Messina (Italy).

A study on hepatitis B and C virus seroprevalence was carried out on blood samples from 327 municipal solid waste workers in Messina (Italy) to verify the hypothesis that this category of workers is at high risk for such diseases. The fact that 32.41% of all the subjects showed previous exposure to hepatitis B virus (HBV) substantiates the need to proceed with compulsory HBV vaccine prophylaxis in this category of workers, also in anticipation of possible medical legal litigations.

Identification of the microorganisms responsible for periodontopathy by Multiplex RT-PCR.

The aim of our research was to identify by bacterial genomic DNA analysis the prevalence of five different species of periodontopathogenic bacteria present in the subgingival biofilm, specifically: Actinobacillus actinomycetemcomitans (Aa), Porphyromonas gingivalis (Pg), Prevotella intermedia (Pi), Bacterioides forsytus (Bf), Treponema denticola (Td). For the analysis we used the systematic Multiplex-PCR-microdent kit with species-specific primers. We studied a group of 48 subjects, 18 males and 30 females, from 18 to 78 years of age. The initial clinical screening enabled us to select, among the group analysed, 24 subjects with signs of active periodontopathy (Group A) and 24 patients without identifiable clinical evidence of the disease used as the control group (Group B). Within the two experimental groups (A and B), the test was found to be positive in 75% of subjects from group A, whereas the test was found to be negative in all the subjects from group B. Our research shows that the Multiplex-PCR system is reliable. Furthermore, the sensitivity and simplicity of this technique, as well as the decrease in working times and the possibility of identifying non-culturable bacteria, since the presence of viable organisms is not essential, make this technique indicated for the simultaneous identification of periodontopathogenic bacteria and might, in perspective, provide a more effective clinical alternative to the techniques of bacterial typing of the subgingival plaque.

[Retrospective survey on epidemiologic monitoring of accidents due to professional exposure to biological agents in A.O.U. "G. Martino" of Messina, Italy)]. / Indagine retrospettiva sul monitoraggio epidemiologico degli infortuni biologici da esposizione professionale nel- i'A.O.U. "G. Martino" di Messina.

The management of healthcare professionals exposed to biological material which may potentially be contaminated with HIV HBVand HCV viruses, is of vital importance in acquiring precise epidemiological data regarding the type and means of exposure, and the efficacy or failure to apply recommended preventive measures. This will make it possible to assess over time which measures need to be implemented or improved. For these reasons we decided to analyze cases of occupational exposure to biological risk occurring in the University Hospital in Messina between 1998 and 2002. Our study highlighted in particular that the most frequently affected category was that of professional nurses (46.74%) and that only 31.72% of the healthcare workers who tested negative for HBsAb were administered vaccine prophylaxis also after the accident. Moreover, it emerged that there is the need to increase the amount and quality of information made available, by changing report forms, with the aim of identifying problems and risky behavior and procedures, and thus make ways to ensure the continued improvement of the accident prevention and management programmes. In fact, in the accident reporting procedure used, it was not possible to specify the precise way in which the accidents happened.

[Survey on microclimatic condition of classroom]. / Indagine sulle condizioni microclimatiche delle aule scolastiche.

The results of a research, in winter and spring, on the microclimatic parameters and lighting in eighteen classrooms of primary schools in the town of Messina, are exposed. In a significant number of classrooms values of temperature and relative humidity are registered not in accordance with Italian standards. Thermal indices (PMV and PPD) showed, in both seasons, discomfort conditions in many rooms. A percentage of dissatisfied persons, significantly higher the 10% (56.8% in winter and 70.3% in spring), has been obtained. We used, also, a questionnaire modified by Fanger to evaluate the thermal subjective sensations of the students. The results point out that the thermal subjective sensations expressed by the students are often in disagreement with the Fanger thermal comfort indices obtained by instrument. The authors believe that the Fanger's indices do not reflect the effective environmental conditions.

[Multicentric survey on hygienic aspects in private dental practice]. / Indagine multicentrica sugli aspetti igienico-sanitari legati all'assistenza odontoiatrica privata.

The aim of this research was to evaluate the knowledge of cross-infection hazards in private dental practices, and their control procedures. The survey, carried out by questionnaire in 11 Italian cities, showed that dental personnel do not completely follow the main procedures for infection control. The interviewed subjects usually wear gloves (95.5%), masks (90.1%) and glasses (91.2%), less frequently caps (23.9%) and coats (54.9%). They use steam sterilizers (92.9%) and periodically check the effectiveness (80.6%). Regarding individuals protection, 20.5% is not vaccinated against HBV and only 55.2% of those previously vaccinated has checked their immunity. Moreover, the majority of subjects underestimate the infection hazards especially for air-transmitted diseases.