Electromagnetic Energy, Absorption, and Casimir Forces. Inhomogeneous Dielectric Media

A general, exact formula is derived for the expectation value of the electromagnetic energy density of an inhomogeneous absorbing and dispersive dielectric medium in thermal equilibrium, assuming that the medium is well approximated as a continuum. From this formula we obtain the formal expression for the Casimir force density. Unlike most previous approaches to Casimir effects in which absorption is either ignored or admitted implicitly through the required analytic properties of the permittivity, we include dissipation explicitly via the coupling of each dipole oscillator of the medium to a reservoir of harmonic oscillators. We obtain the energy density and the Casimir force density as a consequence of the van der Waals interactions of the oscillators and also from Poynting's theorem.Comment: 13 pages, no figures. Updated version with generalization to finite temperature and added example

Complexity analysis of Klein-Gordon single-particle systems

The Fisher-Shannon complexity is used to quantitatively estimate the contribution of relativistic effects to on the internal disorder of Klein-Gordon single-particle Coulomb systems which is manifest in the rich variety of three-dimensional geometries of its corresponding quantum-mechanical probability density. It is observed that, contrary to the non-relativistic case, the Fisher-Shannon complexity of these relativistic systems does depend on the potential strength (nuclear charge). This is numerically illustrated for pionic atoms. Moreover, its variation with the quantum numbers (n, l, m) is analysed in various ground and excited states. It is found that the relativistic effects enhance when n and/or l are decreasing.Comment: 4 pages, 3 figures, Accepted in EPL (Europhysics Letters

Structural anisotropy and orientation-induced Casimir repulsion in fluids

In this work we theoretically consider the Casimir force between two periodic arrays of nanowires (both in vacuum, and on a substrate separated by a fluid) at separations comparable to the period. Specifically, we compute the dependence of the exact Casimir force between the arrays under both lateral translations and rotations. Although typically the force between such structures is well-characterized by the Proximity Force Approximation (PFA), we find that in the present case the microstructure modulates the force in a way qualitatively inconsistent with PFA. We find instead that effective-medium theory, in which the slabs are treated as homogeneous, anisotropic dielectrics, gives a surprisingly accurate picture of the force, down to separations of half the period. This includes a situation for identical, fluid-separated slabs in which the exact force changes sign with the orientation of the wire arrays, whereas PFA predicts attraction. We discuss the possibility of detecting these effects in experiments, concluding that this effect is strong enough to make detection possible in the near future.Comment: 12 pages, 9, figure. Published version with expanded discussio

Structural anisotropy and orientation-induced Casimir repulsion in fluids

In this work we theoretically consider the Casimir force between two periodic arrays of nanowires (both in vacuum, and on a substrate separated by a fluid) at separations comparable to the period. Specifically, we compute the dependence of the exact Casimir force between the arrays under both lateral translations and rotations. Although typically the force between such structures is well-characterized by the Proximity Force Approximation (PFA), we find that in the present case the microstructure modulates the force in a way qualitatively inconsistent with PFA. We find instead that effective-medium theory, in which the slabs are treated as homogeneous, anisotropic dielectrics, gives a surprisingly accurate picture of the force, down to separations of half the period. This includes a situation for identical, fluid-separated slabs in which the exact force changes sign with the orientation of the wire arrays, whereas PFA predicts attraction. We discuss the possibility of detecting these effects in experiments, concluding that this effect is strong enough to make detection possible in the near future.Comment: 12 pages, 9, figure. Published version with expanded discussio

Karakteristik Penderita Demam Berdarah Dengue (DBD) di Rumah Sakit Wahidin Sudirohusodo Makassar Periode Januari – Desember 2010

Penyakit Demam Berdarah Dengue (DBD) atau Dengue Hemorrhagic Fever (DHF) merupakan penyakit akibat infeksi virus Dengue yang masih menjadi problem kesehatan Masyarakat. Penyakit ini ditemukan nyaris diseluruh belahan dunia terutama di negara-negara tropik dan subtropik baik sebagai penyakit endemik maupun epidemik. Hasil studi epidemiologik menunjukan bahwa DBD terutama menyerang kelompok umur Balita sampai dengan umur sekitar 15 tahun serta tidak ditemukan perbedaan signifikan dalam hal kerentanan terhadap serangan dengue antara gender. Penelitian ini bertujuan untuk mengetahui karakteristik Penderita demam berdarah dengue pada pasien rawat inap di Rumah Sakit Wahidin Sudirohusodo Makassar periode Januari-Desember 2010. Metode penelitian dengan pendekatan Deskriptif. Penarikan sampel dilakukan dengan menggunakan metode systematic random sampling. Jumlah sampel sebanyak 205 Responden. Kemudian data dianalisis secara deskriptif. Hasil Penelitian ini Menunjukan bahwa Penderita demam berdarah dengue di Rumah Sakit Wahidin Sudirohusodo Makassar berdasarkan kelompok umur terbanyak adalah kelompok umur 19-49 tahun, jenis kelamin terbanyak adalah jenis kelamin laki-laki, jenis pekerjaan terbanyak adalah berprofesi sebagai pelajar/mahasiswa, tingkat pendidikan terbanyak adalah SMA, sedangkan waktu kejadian tertinggi penderita demam Berdarah dengue adalah pada bulan Maret. Disarankan mencegah terjadinya peningkatan kasus penderita demam berdarah dengue pada golongan umur anak-anak maupun dewasa maka perlu diadakan penyuluhan baik lingkungan keluarga maupun lingkungan sekolah/kampus mengenai upaya pencegahan penyakit demam berdarah dengue. Disamping itu juga Perlu memperkuat kegiatan-kegiatan yang mendukung kearah komunikasi, informasi, dan edukasi yang luas, jelas dan komplit tentang penyakit demam berdarah dengue sehingga masyarakat memiliki sikap positif terhadap masalah-masalah kesehatan khususnya penyakit demam berdarah dengue. Dan perlu adanya tindakan pencegahan penyakit demam berdarah dengue melalui peningkatan frekuensi penyuluhan kesehatan masyarakat mengenai 3M (menguras, menimbun, menutup) tempat-tempat yang dapat menampung air pada bulan-bulan dengan curah hujan dan tingkat kelembaban yang tinggi untuk mencegah perkembangbiakan nyamuk aedes aegypti

Sub-au imaging of water vapour clouds around four Asymptotic Giant Branch stars

We present MERLIN maps of the 22-GHz H2O masers around four low-mass late-type stars (IK Tau U Ori, RT Vir and U Her), made with an angular resolution of ~ 15 milliarcsec and a velocity resolution of 0.1 km s-1. The H2O masers are found in thick expanding shells with inner radii ~ 6 to 16 au and outer radii four times larger. The expansion velocity increases radially through the H2O maser regions, with logarithmic velocity gradients of 0.5--0.9. IK Tau and RT Vir have well-filled H2O maser shells with a spatial offset between the near and far sides of the shell, which suggests that the masers are distributed in oblate spheroids inclined to the line of sight. U Ori and U Her have elongated poorly-filled shells with indications that the masers at the inner edge have been compressed by shocks; these stars also show OH maser flares. MERLIN resolves individual maser clouds, which have diameters of 2 -- 4 au and filling factors of only ~ 0.01 with respect to the whole H2O maser shells. The CSE velocity structure gives additional evidence the maser clouds are density bounded. Masing clouds can be identified over a similar timescale to their sound crossing time (~2 yr) but not longer. The sizes and observed lifetimes of these clouds are an order of magnitude smaller than those around red supergiants, similar to the ratio of low-mass:high-mass stellar masses and sizes. This suggests that cloud size is determined by stellar properties, not local physical phenomena in the wind.Comment: 21 pages, including 14 figures and 8 tables. Accepted for publication in MNRA

Scaling and correlations in the dynamics of forest-fire occurrence

Forest-fire waiting times, defined as the time between successive events above a certain size in a given region, are calculated for Italy. The probability densities of the waiting times are found to verify a scaling law, despite that fact that the distribution of fire sizes is not a power law. The meaning of such behavior in terms of the possible self-similarity of the process in a nonstationary system is discussed. We find that the scaling law arises as a consequence of the stationarity of fire sizes and the existence of a non-trivial ``instantaneous'' scaling law, sustained by the correlations of the process.Comment: Not a long paper, but many figures (but no large size in kb

Relativistic Klein-Gordon charge effects by information-theoretic measures

The charge spreading of ground and excited states of Klein-Gordon particles moving in a Coulomb potential is quantitatively analyzed by means of the ordinary moments and the Heisenberg measure as well as by use of the most relevant information-theoretic measures of global (Shannon entropic power) and local (Fisher's information) types. The dependence of these complementary quantities on the nuclear charge Z and the quantum numbers characterizing the physical states is carefully discussed. The comparison of the relativistic Klein-Gordon and non-relativistic Schrodinger values is made. The non-relativistic limits at large principal quantum number n and for small values of Z are also reached.Comment: Accepted in New Journal of Physic

Competing magnetic orders in the superconducting state of Nd-doped CeRhIn5_{5} under pressure

Applied pressure drives the heavy-fermion antiferromagnet CeRhIn$_{5}$ towards a quantum critical point that becomes hidden by a dome of unconventional superconductivity. Magnetic fields suppress this superconducting dome, unveiling the quantum phase transition of local character. Here, we show that $5\%$ magnetic substitution at the Ce site in CeRhIn$_{5}$, either by Nd or Gd, induces a zero-field magnetic instability inside the superconducting state. This magnetic state not only should have a different ordering vector than the high-field local-moment magnetic state, but it also competes with the latter, suggesting that a spin-density-wave phase is stabilized in zero field by Nd and Gd impurities - similarly to the case of Ce$_{0.95}$Nd$_{0.05}$CoIn$_{5}$. Supported by model calculations, we attribute this spin-density wave instability to a magnetic-impurity driven condensation of the spin excitons that form inside the unconventional superconducting state