Demographic potential as objects of research of social geography

In this article the definition of the term "potential" and "demographic potential". Presented place as part of the concept study of social geography. Demographic potential presented as part of demographic and socio-economic development. The basic factors influence the demographic potential of the area. Indicators which characterized the influence on the demographic potential and its peculiarities were calculation. The basic demographic indicatorsrate of reproduction, fertility, mortality, survival, population growth rate, and sex and age structure of the population. Demographic potential as defined as qualitative and quantitative potential of playing a certain area population now and in the near future

The effect of Helicobacter pylori infection on growth velocity in young children from poor urban communities in Ecuador

SummaryObjectiveTo characterize the potential effects of Helicobacter infections on growth velocity in low socioeconomic status young children in a developing country.MethodsChildren were recruited in poor suburbs of Quito, Ecuador. Normally nourished, mildly and substantially malnourished children (defined using weight-for-age Z-scores at recruitment) formed equal strata. Six height and weight measurements were collected during one year. Enrollment and exit serum samples were analyzed for anti-Helicobacter IgG and exit non-diarrheal feces tested for Helicobacter antigen.ResultsAmong 124 participants (enrollment age 19±9 months), 76 (61%) excreted fecal antigen at exit (were infected). Of these, 44 were seropositive at least once (chronic infections) and 32 tested seronegative both times (new or acute phase infections). The adjusted linear growth velocity during follow-up in children with new infections was reduced by 9.7 (3.8, 15.6) mm/year compared to uninfected controls and 6.4 (0.0, 12.9) mm/year compared to children with chronic infections. The effects of Helicobacter infections on ponderal growth were not significant.ConclusionThese results suggest that linear growth velocity is reduced in young children during the initial phase of Helicobacter infection

Quantum and Topological Criticalities of Lifshitz Transition in Two-Dimensional Correlated Electron Systems

We study electron correlation effects on quantum criticalities of Lifshitz transitions at zero temperature, using the mean-field theory based on a preexisting symmetry-broken order, in two-dimensional systems. In the presence of interactions, Lifshitz transitions may become discontinuous in contrast to the continuous transition in the original proposal by Lifshitz for noninteracting systems. We focus on the quantum criticality at the endpoint of discontinuous Lifshitz transitions, which we call the marginal quantum critical point. It shows remarkable criticalities arising from its nature as a topological transition. At the point, for the canonical ensemble, the susceptibility of the order parameter chi is found to diverge as ln 1/|delta Delta| when the ``neck'' of the Fermi surface collapses at the van Hove singularity. More remarkably, it diverges as 1/|delta Delta| when the electron/hole pocket of the Fermi surface vanishes. Here delta Delta is the amplitude of the mean field measured from the Lifshitz critical point. On the other hand, for the grand canonical ensemble, the discontinuous transitions appear as the electronic phase separation and the endpoint of the phase separation is the marginal quantum critical point. Especially, when a pocket of the Fermi surface vanishes, the uniform charge compressibility kappa diverges as 1/|delta n|, instead of chi, where delta n is the electron density measured from the critical point. Accordingly, Lifshitz transition induces large fluctuations represented by diverging chi and/or kappa. Such fluctuations must be involved in physics of competing orders and influence diversity of strong correlation effects.Comment: 16 pages, 15 figures, to appear in Jounal of the Physical Society of Japa

Optimization with partial differential equations in dieudonné-rashevsky form and conjugate problems

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/46185/1/205_2004_Article_BF00247693.pd