Daily Activities and Social Association of the Bongando in Central Zaire

Daily activities and association patterns of the Bongando, a Bantu speaking people in central Zaire, were studied, using a systematic "self-focal sampling" method. The time spent on the subsistence activities was unexpectedly short, whereas leisure time was abundant. The Bongando are engaged more frequently in non-agricultural activities such as hunting, fishing, and gathering than in agriculture. So they can be described as a "multi-subsistence people" rather than just "farmers." Men tended to concentrate their work on one activity at a time, and women tended to perform two or more activities simultaneously. In the social associations, men and wome rarely associated with each other. Men associated infrequently but evenly with many persons, while women associated more frequently but with only a few specific persons. Although the Bongando have a patrilineal lineage system, they do not clearly segregate the members of their own lineage from the non-members in the association behavior. In daliy life, they do not need to rely on the lineage coalition, probably because their subsistence activities tend to be conducted individually

Drone-Based Land Cover Mapping in the African Rainforest: A Technical Report

The use of drones is expanding rapidly in field research, although their use in tropical African rainforests has not been widely reported. This seems to be because of two issues: the difficulty of flying drones in a tropical forest, and the difficulties that are peculiar to fieldwork in Africa. Based on my experience of operating drones in two regions, Cameroon and DR Congo, this paper provides a general explanation of the issues involved in shooting with a drone, and describes how these operational difficulties can be overcome during field research in a tropical forest setting

NJL Model at Finite Chemical Potential in a Constant Magnetic Field

We investigate the influence of an external magnetic field on chiral symmetry breaking in the Nambu-Jona-Lasinio (NJL) model at finite temperature and chemical potential. According to the Fock-Schwinger proper-time method, we calculate the effective potential in the leading order of the $1/N_c$ expansion. The phase boundary dividing the symmetric phase and the broken phase is illustrated numerically. A complex behavior of the phase boundary is found for large chemical potential.Comment: 6 pages, 2 figures, Poster talk presented at the Workshop on Finite Density QCD at Nara, Japan, 10-12 July 2003; replaced two reference

‘Logic of Gradation’ and ‘Logic of Scission’: Forest Ownership in the Wamba Region of the Democratic Republic of the Congo

This paper was initially published in Japanese (Kimura 2016) and was translated into English with minor revisions.This paper analyzes land ownership in the Wamba region of the Democratic Republic of the Congo. The Bongando people in this area have repeatedly moved from one place to another for a long time and, as a result, their sense of land ownership has gradually faded the further away they moved. They consider land ownership as extending around landmark rivers, which are in clusters that form enclaves. Moreover, their lineage structure is nested. Each lineage that owns land conflicts with others on a variety of issues, e.g., land related issues at one level; however, they are allied on other issues at higher levels. In these ways, the Bongando encompass land ownership from a sense of the ‘logic of gradation’. In recent years, however, nature conservation groups have begun defining nature reserves by parceling out the land and delineating certain areas with uniform obligations and rights. This approach, referred to as the ‘logic of scission’, has caused conflicts among the local people and between the people and the conservation groups. In the future, nature conservation activities will require measures involving a ‘logic of gradation’

Phase structure of NJL model with finite quark mass and QED correction

We study QED corrections to the chiral symmetry breaking in Nambu-Jona-Lasinio (NJL) model with two flavors of quarks. In the model the isospin symmetry is broken by differences of the current quark masses and the electromagnetic charges between up and down quarks. In the leading order of the 1/N expansion we calculate the effective potential of the model with one-loop QED corrections. Evaluating the effective potential, we study an influence of the isospin symmetry breaking on the orientation of chiral symmetry breaking. The current quark mass has an important contribution for the orientation of chiral symmetry breaking.Comment: 7 pages, 8 figures, To appear in the proceedings of the Workshop on Origin of Mass and Strong Coupling Gauge Theories, Nagoya, Japan, 21-24 November 200

Four-fermion Interaction Model in a Constant Magnetic Field at Finite Temperature and Chemical Potential

We investigate an influence of an external magnetic field on chiral symmetry breaking in a four-fermion interaction model at finite temperature and chemical potential. By using the Fock-Schwinger proper-time method, we calculate the effective potential for the four-fermion interaction model at the leading order of the $1/N_c$ expansion. A phase structure of the chiral symmetry breaking is shown on $T$-$\mu$, $H$-$T$ and $\mu$-$H$ planes. The external magnetic field modifies the phase structure. It is found that a new phase appears for a large chemical potential.Comment: 16 pages, 10 figure

CP violation of Extended Higgs sector and Its impact on D^0 -> mu^+ mu^- decay

We study the impact of the CP violation of the extra Higgs sector on $D^0$ decay. The CP even and CP odd neutral Higgs mixing of the two Higgs doublet model is studied and we show how the CP violating effect of the mixing may lead to the longitudinal muon polarization asymmetry of $D^0 \to \mu^+ \mu^-$. The asymmetry of the short-distance contribution is sensitive to the CP violating phase of the extended Higgs sector.Comment: 7 pages, 2 figures, presented as a poster in GUT2012 (YITP,Kyoto,15-17 March2012

Super Restoration of Chiral Symmetry in Massive Four-Fermion Interaction Models

The chiral symmetry is explicitly and spontaneously broken in a strongly interacting massive fermionic system. We study the chiral symmetry restoration in massive four-fermion interaction models with increasing temperature and chemical potential. At high temperature and large chemical potential, we find the boundaries where the spontaneously broken chiral symmetry can be fully restored in the massive Gross--Neveu model. We call the phenomenon super restoration. The phase boundary is obtained analytically and numerically. In the massive Nambu--Jona-Lasinio model, it was found that whether super restoration occurs depends on regularizations. We also evaluate the behavior of the dynamical mass and show the super restoration boundaries on the ordinary phase diagrams.Comment: 11 pages, 13 figure