Fractional gray Lotka-Volterra models with application to cryptocurrencies adoption.

The Fractional Gray Lotka-Volterra Model (FGLVM) is introduced and used for modeling the transaction counts of three cryptocurrencies, namely, Bitcoin, Litecoin, and Ripple. The 2-dimensional study is on Bitcoin and Litecoin, while the 3-dimensional study is on Bitcoin, Litecoin, and Ripple. Dataset from 28 April 2013 to 10 February 2018 provides forecasting values for Bitcoin and Litecoin through the 2-dimensional FGLVM study, while dataset from 7 August 2013 to 10 February 2018 provides forecasting values of Bitcoin, Litecoin, and Ripple through the 3-dimensional FGLVM study. Forecasting values of cryptocurrencies for the n-dimensional FGLVM study, n={2,3} along 100 days of study time, are displayed. The graph and Lyapunov exponents of the 2-dimensional Lotka-Volterra system using the results of FGLVM reveal that the system is a chaotic dynamical system, while the 3-dimensional Lotka-Volterra system displays parabolic patterns in spite of the chaos indicated by the Lyapunov exponents. The mean absolute percentage error indicates that 2-dimensional FGLVM has a good accuracy for the overall forecasting values of Bitcoin and a reasonable accuracy for the last 300 forecasting values of Litecoin, while the 3-dimensional FGLVM has a good accuracy for the overall forecasting values of Bitcoin and a reasonable accuracy for the last 300 forecasting values of both Litecoin and Ripple. Both 2- and 3-dimensional FGLVM analyses evoke a future constant trend in transacting Bitcoin and a future decreasing trend in transacting Litecoin and Ripple. Bitcoin will keep relatively higher transaction counts, with Litecoin transaction counts everywhere superior to that of Ripple.

Epidemiological and molecular characteristics of HIV infection in Gabon, 1986-1994.

OBJECTIVE: To describe trends in the prevalence of HIV-1 infection in different populations in Gabon, and the molecular characteristics of circulating HIV strains. METHODS: Data were collected on HIV prevalence through sentinel surveillance surveys in different populations in Libreville (the capital) and in Franceville. In Libreville, a total of 7082 individuals (hospitalized patients, tuberculosis patients, pregnant women, asymptomatic adults, prisoners) were recruited between 1986 and 1994. In Franceville, we tested 771 pregnant women and 886 healthy asymptomatic adults (1986-1988). Sera were screened for HIV antibodies by enzyme-linked immunosorbent assay (ELISA) and confirmed by Western blot or line immunoassay (LIA). Reactive samples in ELISA were tested for the presence of antibodies to HIV-1 group O viruses by ELISA using V3 peptides from HIV-1 ANT-70 and HIV-1 MVP-5180 followed by confirmation by LIA and a specific Western blot. Seventeen HIV-1 strains were isolated (1988-1993) and a 900 base-pair fragment encoding the env region containing V3, V4, V5 and beginning of gp41 was sequenced and a phylogenetic tree was constructed. RESULTS: HIV prevalence was relatively low and remained stable (0.7-1.6% in pregnant women, 2.1-2.2% in the general population). The prevalence was also stable among prisoners (2.1-2.6%). Among hospitalized and tuberculosis patients prevalence was higher and increased (1.8-12.7% and 1.5-16.2%, respectively). Only three sera had antibodies to HIV-1 group O. The 17 HIV-1 strains represent six different genetic subtypes including type O. CONCLUSION: Our data from 1986 to 1994 show a stable and low HIV prevalence in Gabon, and a high genetic diversity of HIV-1 strains. This, also observed in Cameroon, is in contrast to that found elsewhere in Africa. Differences in rate of spread of HIV infection are probably explained by interplay between numerous factors. The role of different HIV subtypes in the dynamics of the HIV epidemic should be examined further.

[Current aspects of sickle cell disease in children in Gabon]. / Aspects actuels de la drépanocytose chez l'enfant au Gabon.

BACKGROUND: Clinical manifestations and course of sickle-cell anemia are variable. Knowledge about the factors, possibly geographic, that influence prognosis are still scanty. POPULATION AND METHODS: Data of hospitalization and management of children with sickle-cell disease were studied during two years (1992-1993) in the Pediatric Unit of Libreville Hospital. They concerned 205 admissions of 171 children and 131 outpatients. RESULTS: The main causes of hospitalization were: acute anemia (36 cases before the age of 5 years); painful crisis whose frequency increased with age (23% before 5 years, 35% between 5 and 10, 42% after 10 years); infections, essentially pulmonary occurring early, and bone infections at any age. Eight children died (because a complication of their disease). Among the 131 outpatients, half were detected because pyrexia, anemia and/or more often "hand-foot syndrome". More than 60% had hepatomegaly, one third still had splenomegaly after five years of age and more than one third was icteric. More than half children older than ten years had growth disorders. Mean hemoglobin level was 7 g/dL. 21 of the 83 tested children for HBsAg were positive and only one out of 79 was positive for HIV. CONCLUSIONS: Clinical manifestations and course of sickle-cell anemia in our patients are similar to those reported in Congolese children. Genetic and environmental factors may be responsible for differences with children from other, in particular French, cohorts.

Threat of number.

PIP: Population growth in Nigeria is particularly problematic because population is expected to increase dramatically from 115 million to 280 million in 25 years. At present there are 206 million in the entire West African sub-region. The population density issues within Nigeria and the region are also reasons for concern. About 50% of Nigeria's population is presently under 20 years old, and the likelihood of this proportion continuing for some time is very high. Population growth will mean increased demand for housing, food, health services, education, electricity, and water. The UN has issued warnings that population pressures strain scarce resources, the environment, and people's adjustment. A national population policy was established in order to improve the standard of living of Nigerians and to promote health and welfare among the population. The policy aims to lower population growth through voluntary family planning and through reductions in infant, child, and maternal mortality. In 1989 the Nigerian government in conjunction with the US Agency for International Development (USAID) committed about $100 million in a 5-year program to strengthen family planning: $33 million from Nigeria and $67 million from USAID. The federal Ministry of Health would maintain family health services with integrated primary health care and with promotion of the balance between resources and number of children. Other international efforts have contributed to family planning programs. For example, the Planned Parenthood Federation of Nigeria focused on adult males and youth. Oral contraceptives and injectables have received criticism in Nigeria for having undesirable health consequences despite their popularity worldwide, the absence of significant side effects, and international and national support. Vasectomy is becoming more popular in Oyo state. Family planning has not been popular because of many misconceptions. Both Muslim and Catholic leaders have encouraged responsible parenthood, although Catholic leaders reject contraception.^ieng

Planners in dark tunnel.

PIP: Augustus Aikhomu, Nigeria's vice-president and a retired admiral, stated in 1991 that accurate population figures were necessary for social and economic planning and policy. Celestine Mezue, assistant director of Bendel state's population commission, stated that non-availability of reliable population statistics was responsible for the failures in national development planning. Two sectors (rural and transportation) have been greatly affected by the lack of data. Educational institutions have been particularly affected by overcrowding or rejection of students due to lack of space and facilities. Over 1 million children must compete for 1000 spaces in primary schools. Complaints at the local level have been directed to insufficient funding for teacher's salaries. About 255,000 students applied for university admission, and only 12% were admitted during 1989-90. Scholarships declined from 1859 awards in 1976 to none in 1984. Post-graduate scholarships declined from 2000 in 1976 to none in 1984. Planning for future health services has also been restricted by lack of accurate statistics. There was a gap between availability of low-income housing and the need for the burgeoning population. Population growth has been estimated at 2.0-3.3%; housing will need to be increased by 2.2-3.5 million more units by 2015. Population growth and congestion in cities has resulted in environmental pollution. The population policy in 1989 recommended 4.0 children per woman. In 1990 a demographic and health survey found fertility to be 6.0 children per woman. Improved data collection and the government support for family planning are needed to reduce population growth in Nigeria.^ieng