P. Falciparum Resisten Terhadap Chloroquine Di Kabupaten Jepara, Jawa Tengah

Twenty indigenous falciparum cases were subjected to either an in vivo and/or in-vitro (macro and micro) test, held during a WHO assisted training activity in Jepara, Central Jawa, in May 1981, to assess its susceptibility to chloroquine. Result showed that all cases were resistant to chloroquine. Ten cases underwent in-vivo test, revealing 9 resistant at RI and 1 resistant at RII level. This is the first report of falciparum found in Jawa

Metastability in Josephson transmission lines

Thermal activation and macroscopic quantum tunneling in current-biased discrete Josephson transmission lines are studied theoretically. The degrees of freedom under consideration are the phases across the junctions which are coupled to each other via the inductances of the system. The resistively shunted junctions that we investigate constitute a system of N interacting degrees of freedom with an overdamped dynamics. We calculate the decay rate within exponential accuracy as a function of temperature and current. Slightly below the critical current, the decay from the metastable state occurs via a unique ("rigid") saddlepoint solution of the Euclidean action describing the simultaneous decay of the phases in all the junctions. When the current is reduced, a crossover to a regime takes place, where the decay occurs via an "elastic" saddlepoint solution and the phases across the junctions leave the metastable state one after another. This leads to an increased decay rate compared with the rigid case both in the thermal and the quantum regime. The rigid-to-elastic crossover can be sharp or smooth analogous to first- or second- order phase transitions, respectively. The various regimes are summarized in a current-temperature decay diagram.Comment: 11 pages, RevTeX, 3 PS-figures, revised versio

Macroscopic Quantum Tunneling of a Domain Wall in a Ferromagnetic Metal

The macroscopic quantum tunneling of a planar domain wall in a ferromagnetic metal is studied based on the Hubbard model. It is found that the ohmic dissipation is present even at zero temperature due to the gapless Stoner excitation, which is the crucial difference from the case of the insulating magnet. The dissipative effect is calculated as a function of width of the wall and is shown to be effective in a thin wall and in a weak ferromagnet. The results are discussed in the light of recent experiments on ferromagnets with strong anisotropy. PACS numbers:75.60.Ch, 03.65.Sq, 75.10.LpComment: 13page

20 Years of Progress in Typhoid Research

In 1981, the reported number of cases of typhoid fever in Indonesia was 19,596, increasing to 26,606 m 1986, most of the increase was due to improved detection and recognition of the pathogen. A more realistic estimate of incidence for this underreported and underdiagnosed disease would be from 540,000 to 1,210,000 cases per year. This was based on results of a household survey done by Budiarso R. et al. in 1980 and 1986, and on result of a community surveillance done by Ruwido and Simanjuntak et al. from 1983-1988. These studies were done in Plaju, South Sumatera, representing an urban area and Paseh, West Java, representing a semi-rural area. The results showed that the incidence rate of typhoid fever in the semi rural area was 358/100,000 population/year, and between 760-810/100,000 population/year in the urban area. These studies also indicated that the high risk group in the population was school age children between ages of 3-19 years. From other observations, it is also noted that the case fatality in urbanized and growing areas of Indonesia, may be higher than it is reported in other areas of the worl

Crossovers in the thermal decay of metastable states in discrete systems

The thermal decay of linear chains from a metastable state is investigated. A crossover from rigid to elastic decay occurs when the number of particles, the single particle energy barrier or the coupling strength between the particles is varied. In the rigid regime, the single particle energy barrier is small compared to the coupling strength and the decay occurs via a uniform saddlepoint solution, with all degrees of freedom decaying instantly. Increasing the barrier one enters the elastic regime, where the decay is due to bent saddlepoint configurations using the elasticity of the chain to lower their activation energy. Close to the rigid-to-elastic crossover, nucleation occurs at the boundaries of the system. However, in large systems, a second crossover from boundary to bulk nucleation can be found within the elastic regime, when the single particle energy barrier is further increased. We compute the decay rate in the rigid and in the elastic regimes within the Gaussian approximation. Around the rigid-to-elastic crossover, the calculations are performed beyond the steepest descent approximation. In this region, the prefactor exhibits a scaling property. The theoretical results are discussed in the context of discrete Josephson transmission lines and pancake vortex stacks that are pinned by columnar defects.Comment: 13 pages, RevTeX, 7 PS-figure

Microscopic chaos from Brownian motion in a one-dimensional anharmonic oscillator chain

The problem of relating microscopic chaos to macroscopic behavior in a many-degrees-of-freedom system is numerically investigated by analyzing statistical properties associated to the position and momentum of a heavy impurity embedded in a chain of nearest-neighbor anharmonic Fermi-Pasta-Ulam oscillators. For this model we have found that the behavior of the relaxation time of the momentum autocorrelation function of the impurity is different depending on the dynamical regime (either regular or chaotic) of the lattice.Comment: 5 pages REVTeX, 6 eps figures, to appear in Phys. Rev.

Macroscopic Quantum Tunneling and Dissipation of Domain Wall in Ferromagnetic Metals

The depinning of a domain wall in ferromagentic metal via macroscopic quantum tunneling is studied based on the Hubbard model. The dynamics of the magnetization verctor is shown to be governed by an effective action of Heisenberg model with a term non-local in time that describes the dissipation due to the conduction electron. Due to the existence of the Fermi surface there exists Ohmic dissipation even at zero temperature, which is crucially different from the case of the insulator. Taking into account the effect of pinning and the external magnetic field the action is rewritten in terms of a collective coordinate, the position of the wall, $Q$. The tunneling rate for $Q$ is calculated by use of the instanton method. It is found that the reduction of the tunneling rate due to the dissipation is very large for a thin domain wall with thickness of a few times the lattice spacing, but is negligible for a thick domain wall. Dissipation due to eddy current is shown to be negligible for a wall of mesoscopic size.Comment: of pages 26, to appear in "Quantum Tunneling of Magnetization, ed. B. Barbara and L. Gunther (Kluwer Academic Pub.), Figures available by FAX (81-48-462-4649

Macroscopic Quantum Tunneling of a Fluxon in a Long Josephson Junction

Macroscopic quantum tunneling (MQT) for a single fluxon moving along a long Josephson junction is studied theoretically. To introduce a fluxon-pinning force, we consider inhomogeneities made by modifying thickness of an insulating layer locally. Two different situations are studied: one is the quantum tunneling from a metastable state caused by a single inhomogeneity, and the other is the quantum tunneling in a two-state system made by two inhomogeneities. In the quantum tunneling from a metastable state, the decay rate is estimated within the WKB approximation. Dissipation effects on a fluxon dynamics are taken into account by the Caldeira-Leggett theory. We propose a device to observe quantum tunneling of a fluxon experimentally. Required experimental resolutions to observe MQT of a fluxon seem attainable within the presently available micro-fabrication technique. For the two-state system, we study quantum resonance between two stable states, i.e., macroscopic quantum coherence (MQC). From the estimate for dissipation coefficients due to quasiparticle tunneling, the observation of MQC appears to be possible within the Caldeira-Leggett theory.Comment: 30 pages LaTeX including 11 PS figures, using jpsj.sty. To be published on J. Phys. Soc. Jpn. Overestimates for damping amplitude is correcte

Shigella spp. surveillance in Indonesia: the emergence or reemergence of S. dysenteriae.

From June 1998 through November 1999, Shigella spp. were isolated in 5% of samples from 3,848 children and adults with severe diarrheal illness in hospitals throughout Indonesia. S. dysenteriae has reemerged in Bali, Kalimantan, and Batam and was detected in Jakarta after a hiatus of 15 years

Magnetic Field Dependence of Macroscopic Quantum Tunneling and Coherence of Ferromagnetic Particle

We calculate the quantum tunneling rate of a ferromagnetic particle of $\sim 100 \AA$ diameter in a magnetic field of arbitrary angle. We consider the magnetocrystalline anisotropy with the biaxial symmetry and that with the tetragonal symmetry. Using the spin-coherent-state path integral, we obtain approximate analytic formulas of the tunneling rates in the small $\epsilon (=1- H/H_c)$-limit for the magnetic field normal to the easy axis ($\theta_H = \pi/2$), for the field opposite to the initial easy axis ($\theta_H = \pi$), and for the field at an angle between these two orientations ($\pi/2 << \theta_H << \pi$). In addition, we obtain numerically the tunneling rates for the biaxial symmetry in the full range of the angle $\theta_H$ of the magnetic field ($\pi/2 < \theta_H \leq \pi$), for the values of \epsilon =0.01 and 0.001.Comment: 25 pages of text (RevTex) and 4 figures (PostScript files), to be published in Phys. Rev.