About the relationship between the zooplankton and fluctuating water levels of Lago Camaleão, a Central Amazonian várzea lake

A two-year study of the composition and abundance of the zooplankton was conducted in an Amazonian vãrzea lake, Lago Camaleão. Rotifers were dominant in terms of both species numbers and density. The extremely low standing-stock observed during the high water period is attributed to prevailing poor oxygen conditions and, during extreme floods, current. The species associations of rotifers also reflect the flooding regime and its consequences

Design considerations for the Tandem Junction Solar Cell

Structure and operation of the tandem junction cell (TJC) are described. The impact of using only back contacts is discussed. A model is presented which explains operation of the TJC in terms of transistor action. The model is applied to predict TJC performance as a function of physical parameters

NMR evidence for Friedel-like oscillations in the CuO chains of ortho-II YBa2_2Cu3_3O6.5_{6.5}

Nuclear magnetic resonance (NMR) measurements of CuO chains of detwinned Ortho-II YBa$_2$Cu$_3$O$_{6.5}$ (YBCO6.5) single crystals reveal unusual and remarkable properties. The chain Cu resonance broadens significantly, but gradually, on cooling from room temperature. The lineshape and its temperature dependence are substantially different from that of a conventional spin/charge density wave (S/CDW) phase transition. Instead, the line broadening is attributed to small amplitude static spin and charge density oscillations with spatially varying amplitudes connected with the ends of the finite length chains. The influence of this CuO chain phenomenon is also clearly manifested in the plane Cu NMR.Comment: 4 pages, 3 figures, refereed articl

Further taxonomical studies of the Rotifera from Lago Camaleão, a Central Amazonian várzea lake (Ilha de Marchantaria, Rio Solimões, Amazonas, Brazil)

175 species of rotifers were identified in samples collected in lago Camaleão, an Amazonian varzea lake. 24 species which had previously been found in the lake (KOSTE & ROBERTSON 1983) did not reoccur, but were "replaced" by 30 others. Among these, new records for the Amazon region include: Atrochus tentaculatus WIERZEJSKI, 1893, Brachionus bidentatus inermis ANDERSON, 1899, Cephalodella catellina catellina (O. F. MÜLLER 1786), Eosphora anthadis HARRING & MYERS, 1922 and Monommata cf. actices MYERS, 1930. One new species is described, Cephalodella friebei, and the present taxonomic status of Filinia saltator (GOSSE 1886) and Macrochaetus serrcus (THORPE 1893) is discussed

No Hubble Bubble in the Local Universe

Zehavi et al. (1998) have suggested that the Hubble flow within 70/h Mpc may be accelerated by the existence of a void centered on the Local Group. Its underdensity would be ~20 %, which would result in a local Hubble distortion of about 6.5 %. We have combined the peculiar velocity data of two samples of clusters of galaxies, SCI and SCII, to investigate the amplitude of Hubble distortions to 200/h Mpc. Our results are not supportive of that conclusion. The amplitude of a possible distortion in the Hubble flow within 70/h Mpc in the SCI+SCII merged data is 0.010\pm0.022. The largest, and still quite marginal, geocentric deviation from smooth Hubble flow consistent with that data set is a shell with (Delta H)/H =0.027\pm0.023, centered at hd = 101 Mpc and extending over some 30/h Mpc. Our results are thus consistent with a Hubble flow that, on distances in excess of about 50/h Mpc, is remarkably smooth.Comment: 11 pages, 1 tables, 1 figure; uses AAS LaTex; to appear in ApJ Nov 9

Wind tunnel wall effects in V/STOL model testing Final report, 1 Oct. 1965 - 31 Mar. 1967

Improved method for determining wind tunnel wall effects in V/STOL model testin

Superfluid Density in a Highly Underdoped YBCO Superconductor

The superfluid density rho_s(T) = 1/lambda^2(T) has been measured at 2.64 GHz in highly underdoped YBCO, at 37 dopings with T_c between 3 K and 17 K. Within limits set by the transition width Delta T_c ~ 0.4 K, rho_s(T) shows no evidence of critical fluctuations as T goes to T_c, with a mean-field-like transition and no indication of vortex unbinding. Instead, we propose that rho_s displays the behaviour expected for a quantum phase transition in the (3 + 1)-dimensional XY universality class, with rho_s0 ~ (p - p_c), T_c ~ (p - p_c)^1/2 and rho_s(T) ~ (T_c - T)^1 as T goes to T_c.Comment: 4 pages, 5 figures; final version of pape