Comment on 'Anti-tumour activity of abiraterone and diethylstilboestrol when administered sequentially to men with castration-resistant prostate cancer'

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Rat floods and water floods: the ecological and sociological dynamics of rodent management in Bangladesh

Chakma, N., Belmain, S.R., Sarker, N.J., Sarker, S.U., Kamal, N.Q., Sarker, S.K

Dynamical Casimir effect for magnons in a spinor Bose-Einstein condensate

Magnon excitation in a spinor Bose-Einstein condensate by a driven magnetic field is shown to have a close analogy with the dynamical Casimir effect. A time-dependent external magnetic field amplifies quantum fluctuations in the magnetic ground state of the condensate, leading to magnetization of the system. The magnetization occurs in a direction perpendicular to the magnetic field breaking the rotation symmetry. This phenomenon is numerically demonstrated and the excited quantum field is shown to be squeezed.Comment: 8 pages, 3 figure

Schwinger-Boson Mean-Field Theory of Mixed-Spin Antiferromagnet L2BaNiO5L_2BaNiO_5

The Schwinger-boson mean-field theory is used to study the three-dimensional antiferromagnetic ordering and excitations in compounds $L_2BaNiO_5$, a large family of quasi-one-dimensional mixed-spin antiferromagnet. To investigate magnetic properties of these compounds, we introduce a three-dimensional mixed-spin antiferromagnetic Heisenberg model based on experimental results for the crystal structure of $L_2BaNiO_5$. This model can explain the experimental discovery of coexistence of Haldane gap and antiferromagnetic long-range order below N\'{e}el temperature. Properties such as the low-lying excitations, magnetizations of $Ni$ and rare-earth ions, N\'{e}el temperatures of different compounds, and the behavior of Haldane gap below the N\'{e}el temperature are investigated within this model, and the results are in good agreement with neutron scattering experiments.Comment: 12 pages, 6 figure

Smaller sample sizes for phase II trials based on exact tests with actual error rates by trading-off their nominal levels of significance and power

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A strong-coupling expansion for the Hubbard model

We reconsider the strong-coupling expansion for the Hubbard model recently introduced by Sarker and Pairault {\it et al.} By introducing slave particles that act as projection operators onto the empty, singly occupied and doubly occupied atomic states, the perturbation theory around the atomic limit distinguishes between processes that do conserve or do not conserve the total number of doubly occupied sites. This allows for a systematic $t/U$ expansion that does not break down at low temperature ($t$ being the intersite hopping amplitude and $U$ the local Coulomb repulsion). The fermionic field becomes a two-component field, which reflects the presence of the two Hubbard bands. The single-particle propagator is naturally expressed as a function of a $2 \times 2$ matrix self-energy. Furthermore, by introducing a time- and space-fluctuating spin-quantization axis in the functional integral, we can expand around a ``non-degenerate'' ground-state where each singly occupied site has a well defined spin direction (which may fluctuate in time). This formalism is used to derive the effective action of charge carriers in the lower Hubbard band to first order in $t/U$. We recover the action of the t-J model in the spin-hole coherent-state path integral. We also compare our results with those previously obtained by studying fluctuations around the large-$U$ Hartree-Fock saddle point.Comment: 20 pages RevTex, 3 figure

Complexes of stationary domain walls in the resonantly forced Ginsburg-Landau equation

The parametrically driven Ginsburg-Landau equation has well-known stationary solutions -- the so-called Bloch and Neel, or Ising, walls. In this paper, we construct an explicit stationary solution describing a bound state of two walls. We also demonstrate that stationary complexes of more than two walls do not exist.Comment: 10 pages, 2 figures, to appear in Physical Review

Patogenost i patološke promjene u zlatnih ribica, Carasius auratus (L.) pokusno inficiranih bakterijom Chryseobacterium sp. PLI2

The pathogenicity and pathology of Chryseobacterium sp. PLI2 in experimentally challenged Carassius auratus goldfish were studied. Chryseobacterium sp. PLI2 produced typical chryseobacteriosis symptoms in intraperitoneally challenged and abrasion-bath treated C. auratus. The LD50 was determined to be 3.13×107 cells/fish. It caused 40% mortality within 3 weeks in abraded fish when challenged at a level of ≈2.50×107 cells/mL. The challenged fish were lethargic, anorectic and exhibited erratic movement. With disease progression, they all had white patches on the gills, excessive mucus secretion, caudal peduncle lesions, focal cutaneous haemorrhages, haemorrhagic eye and opercula, scale loss, skin discoloration, skin peeling, emaciation, pale kidneys and black spleen. Histologically, inflammation of the cartilaginous tissue, fusion of the lamellae and extensive necrosis were noticed in the gills. The spleen showed sinusoidal dilation, melanomacrophage aggregate, marginated leucocytes with a hypertrophied nucleus and necrotized areas. Granuloma-like formations, inflamed renal tubules and glomerulus, extensive necrosis, mild melanomacrophage aggregate, acentric nucleus, constricted renal tubules with a vacuolated surrounding, hypoplastic haematopoietic tissue, degeneration of tubular epithelium with proteinaceous casts in the tubular lumen, and fibrosis around the renal tubules were observed in the kidneys. The challenge experiment indicated that Chryseobacterium sp. can cause systemic disease in goldfish.U ovome je radu analizirana patogenost i patološke promjene u zlatnih ribica Carasius auratus pokusno inficiranih bakterijom Chryseobacterium sp. PLI2. Lezije tipične za krizeobakteriozu razvile su se u intraperitonealno inficiranih i abrazijskom kupkom tretiranih riba. Određena je LD50 od 3,13×107 stanica/ribi, koja je uzrokovala 40 % pomora unutar tri tjedna u riba inficiranih dozom od 2,50×107 stanica/mL. Zaražene su ribe bile letargične, anoreksične i ataksične. S razvojem bolesti sve su razvile bijele mrlje po škrgama, intenzivan sluzavi sekret, lezije na stražnjim pedunkulima, žarišna krvarenja po koži, krvarenja u oku i škržnim poklopcima, ljuštenje kože i mršavljenje, a utvrđeni su i blijedi bubrezi i tamno obojena slezena. Histološki je na škrgama utvrđena upala hrskavičnog tkiva, spajanje lamela i proširene nekroze. U slezeni je zamijećeno proširenje sinusoida, nakupljanje melanomakrofaga, marginacija leukocita s hipertofičnom jezgrom i nekrotičnim područjima. U bubrezima je uočeno formiranje granuloma te upalne promjene u tubulima i glomerulima, proširene nekroze, blago nakupljanje melanomakrofaga, acentrične jezgre, suženje tubula s vakuoliranom okolinom, hipoplazija hematopoetskog tkiva, distrofija tubularnog epitela s talozima proteina u lumenu i fibroza okolnog područja. Pokus je dokazao da Chryseobacterium sp. može uzrokovati opću bolest u zlatnih ribica

Temperature dependence of the resistivity in the double-exchange model

The resistivity around the ferromagnetic transition temperature in the double exchange model is studied by the Schwinger boson approach. The spatial spin correlation responsible for scattering of conduction electrons are taken into account by adopting the memory function formalism. Although the correlation shows a peak lower than the transition temperature, the resistivity in the ferromagnetic state monotonically increases with increasing temperature due to a variation of the electronic state of the conduction electron. In the paramagnetic state, the resistivity is dominated by the short range correlation of scattering and is almost independent of the temperature. It is attributed to a cancellation between the nearest-neighbor spin correlation, the fermion bandwidth, and the fermion kinetic energy. This result implies the importance of the temperature dependence of the electronic states of the conduction electron as well as the localized spin states in both ferromagnetic and paramagnetic phases.Comment: RevTex, 4 pages, 4 PostScript figures, To appear in Phys. Rev.

Canted Ferromagnetism in Double Exchange Model with on-site Coulomb Repulsion

The double exchange model with on-site Coulomb repulsion is considered. Schwinger-bosons representation of the localized spins is used and two spin-singlet Fermion operators are introduced. In terms of the new Fermi fields the on-site Hund's interaction is in a diagonal form and the true magnons of the system are identified. The singlet fermions can be understood as electrons dressed by a cloud of repeatedly emitted and reabsorbed magnons. Rewritten in terms of Schwinger-bosons and spin-singlet fermions the theory is U(1) gauge invariant. We show that spontaneous breakdown of the gauge symmetry leads to \emph{\textbf{canted ferromagnetism with on-site spins of localized and delocalized electrons misaligned}}. On-site canted phase emerges in double exchange model when Coulomb repulsion is large enough. The quantum phase transition between ferromagnetism and canted phase is studied varying the Coulomb repulsion for different values of parameters in the theory such as Hund's coupling and chemical potential.Comment: 8 pages, 6 figure