Theory of ultrasonic diffraction by damage developed in thin laminated composites

The apparent attenuation which would result if certain damage states (transverse cracks and delaminations) are introduced into a graphite/epoxy laminate through which an ultrasonic wave passes is investigated. Experimental data for two different laminates are presented which shows changes in the apparent attenuation of about one db. These changes generally occur at loads which correspond to the range predicted for the formation of the damage. The predicted changes in the attenuation for several simple and common damage states are well within the range of experimental values

Utilization of Life Feed Alona SP., Boiled Egg Yolk and Commercial Feed Toward Survival Rate of Betta Fish Larvae

Tujuan penelitian ini adalah untuk mendapatkan laju kelangsungan hidup larva ikan betta (cupang) yang dibeerikan pakan alami Alona sp., rebusan kuning telur dan pakan komersil selama 21 hari. Analisis data dilakukan dengan ANOVA one way, dan dilanjutkan dengan uji BNJ (Tukey). Hasil laju kelangsungan hidup adalah sebagai berikut, perlakuan dengan pakan alami Alona sp. 56%, perlakuan dengan rebusan kuning telur 26%, dan perlakuan dengan pakan komersil 0%. Hasil uji statistik menunjukan adanya perbedaan yang nyata. Nilai signifikan p <.0002 (<.05). Parameter kualitas air yang diukur selama penelitian adalah suhu 26ºC

Phase diagram of localization in a magnetic field

The phase diagram of localization is numerically calculated for a three-dimensional disordered system in the presence of a magnetic field using the Peierls substitution. The mobility edge trajectory shifts in the energy-disorder space when increasing the field. In the band center, localized states near the phase boundary become delocalized. The obtained field dependence of the critical disorder is in agreement with a power law behavior expected from scaling theory. Close to the tail of the band the magnetic field causes localization of extended states.Comment: 4 pages, RevTeX, 3 PS-figures (4 extra references are included, minor additions), to appear in Phys. Rev. B as a Brief Repor

Anomalous diffusion at the Anderson transitions

Diffusion of electrons in three dimensional disordered systems is investigated numerically for all the three universality classes, namely, orthogonal, unitary and symplectic ensembles. The second moment of the wave packet $$ at the Anderson transition is shown to behave as $\sim t^a (a\approx 2/3)$. From the temporal autocorrelation function $C(t)$, the fractal dimension $D_2$ is deduced, which is almost half the value of space dimension for all the universality classes.Comment: Revtex, 2 figures, to appear in J. Phys. Soc. Jpn.(1997) Fe

An Extended Network of Genomic Maintenance in the Archaeon Pyrococcus abyssi Highlights Unexpected Associations between Eucaryotic Homologs.

In Archaea, the proteins involved in the genetic information processing pathways, including DNA replication, transcription, and translation, share strong similarities with those of eukaryotes. Characterizations of components of the eukaryotic-type replication machinery complex provided many interesting insights into DNA replication in both domains. In contrast, DNA repair processes of hyperthermophilic archaea are less well understood and very little is known about the intertwining between DNA synthesis, repair and recombination pathways. The development of genetic system in hyperthermophilic archaea is still at a modest stage hampering the use of complementary approaches of reverse genetics and biochemistry to elucidate the function of new candidate DNA repair gene. To gain insights into genomic maintenance processes in hyperthermophilic archaea, a protein-interaction network centred on informational processes of Pyrococcus abyssi was generated by affinity purification coupled with mass spectrometry. The network consists of 132 interactions linking 87 proteins. These interactions give insights into the connections of DNA replication with recombination and repair, leading to the discovery of new archaeal components and of associations between eucaryotic homologs. Although this approach did not allow us to clearly delineate new DNA pathways, it provided numerous clues towards the function of new molecular complexes with the potential to better understand genomic maintenance processes in hyperthermophilic archaea. Among others, we found new potential partners of the replication clamp and demonstrated that the single strand DNA binding protein, Replication Protein A, enhances the transcription rate, in vitro, of RNA polymerase. This interaction map provides a valuable tool to explore new aspects of genome integrity in Archaea and also potentially in Eucaryotes

Does a magnetic field modify the critical behaviour at the metal-insulator transition in 3-dimensional disordered systems?

The critical behaviour of 3-dimensional disordered systems with magnetic field is investigated by analyzing the spectral fluctuations of the energy spectrum. We show that in the thermodynamic limit we have two different regimes, one for the metallic side and one for the insulating side with different level statistics. The third statistics which occurs only exactly at the critical point is {\it independent} of the magnetic field. The critical behaviour which is determined by the symmetry of the system {\it at} the critical point should therefore be independent of the magnetic field.Comment: 10 pages, Revtex, 4 PostScript figures in uuencoded compressed tar file are appende

Charge Localization in Disordered Colossal-Magnetoresistance Manganites

The metallic or insulating nature of the paramagnetic phase of the colossal-magnetoresistance manganites is investigated via a double exchange Hamiltonian with diagonal disorder. Mobility edge trajectory is determined with the transfer matrix method. Density of states calculations indicate that random hopping alone is not sufficient to induce Anderson localization at the Fermi level with 20-30% doping. We argue that the metal-insulator transtion is likely due to the formation of localized polarons from nonuniform extended states as the effective band width is reduced by random hoppings and electron-electron interactions.Comment: 4 pages, RevTex. 4 Figures include

Pseudo-Sylvester domains and skew laurent polynomials over firs

Building on recent work of Jaikin-Zapirain, we provide a homological criterion for a ring to be a pseudo-Sylvester domain, that is, to admit a division ring of fractions over which all stably full matrices become invertible. We use the criterion to study skew Laurent polynomial rings over free ideal rings (firs). As an application of our methods, we prove that crossed products of division rings with free-by-{infinite cyclic} and surface groups are pseudo-Sylvester domains unconditionally and Sylvester domains if and only if they admit stably free cancellation. This relies on the recent proof of the Farrell--Jones conjecture for normally poly-free groups and extends previous results of Linnell--L\"uck and Jaikin-Zapirain on universal localizations and universal fields of fractions of such crossed products

Growth study of coi fish larvae fed chydoridae

First culture media for chydoridae used horse manure dried in the sun with a composition of 10 grams and 50 grams of soil dissolved in 1 L of water for 5 days, then filtered and diluted three times. Laboratory-scale cultures were carried out in a 500 ml volume jar containing horse manure culture media; then in the process fed with bread yeast and rice bran (0.05 gr yeast and rice bran/500 ml) every 3 days. Mass culture uses 12 jar containers with a volume of 3 L.The administration of chydoridae to two-day old koi fish larvae was carried out with the following treatments: treatment A, which was ornamental fish fed with boiled egg yolk in ad libitum; treatment B is ornamental fish fed with 5 individual chydoridae/ml and treatment C, which is not given any food with three replications. The design of the response in this study was to see the survival rate of ornamental fish larvae (%).The results of measurements of water quality during the study showed that the temperature during the study was 27°C, while the pH was 7. From the statistical analysis it was found that administration of chydoridae had a significant effect on the survival of two-day-old koi fish larvae which were kept for 14 days.Keywords: chydoridae, life feed, ornamental fish larvae, growthABSTRAKMedia kultur awal chydoridae menggunakan kotoran kuda yang dikeringkan di bawah sinar matahari dengan komposisi 10 gram kotoran kuda serta 50 gram tanah yang dilarutkan dalam 1 L air selama 5 hari, kemudian dilakukan penyaringan dan diencerkan sebanyak tiga kali.  Kultur skala laboratorium dilakukan dalam wadah toples dengan volume 500 ml berisi media kultur kotoran kuda; selanjutnya dalam proses kultur chydoridae diberi makan ragi roti dan dedak (0,05 gr ragi dan dedak /500 ml) setiap 3 hari sekali. Kultur massal menggunakan wadah toples sebanyak 12 buah dengan volume 3 L dengan mengikuti metode pada kultur skala laboratorium.Pemberian chydoridae kepada larva ikan koi yang berumur dua hari dilakukan dengan beberapa perlakuan sebagai berikut : perlakuan A yaitu  ikan hias diberi makan kuning telur rebus secara ad libitum; perlakuan B yaitu  ikan hias diberi makan chydoridae 5 individu/ml dan perlakuan C yaitu  ikan hias tidak diberi makan apapun dengan tiga ulangan.  Rancangan respons dalam penelitian ini adalah melihat laju kelangsungan hidup larva ikan hias (%).Hasil pengukuran kualitas air selama penelitian menunjukkan, suhu selama penelitian adalah 27 °C, sedangkan pH adalah 7.  Dari hasil analisis statistik diperoleh bahwa pemberian chydoridae sangat memberi pengaruh nyata kepada kelangsungan hidup larva ikan koi berumur dua hari yang dipelihara selama 14 hari.Kata kunci: chydoridae, pakan alami, larva ikan hias, pertumbuha

Electrical properties of isotopically enriched neutron-transmutation-doped ^{70} Ge:Ga near the metal-insulator transition

We report the low temperature carrier transport properties of a series of nominally uncompensated neutron-transmutation doped (NTD) ^{70} Ge:Ga samples very close to the critical concentration N_c for the metal-insulator transition. The concentration of the sample closest to N_c is 1.0004N_c and it is unambiguously shown that the critical conductivity exponent is 0.5. Properties of insulating samples are discussed in the context of Efros and Shklovskii's variable range hopping conduction.Comment: 8 pages using REVTeX, 8 figures, published versio