Some Monogenetic Trematodes of Marine Fishes from Fiji

This paper describes three new species of monogenetic trematodes collected by the senior author from fishes at Suva, Fiji, in 1951. A new genus is named for one of these species. A fourth species, previously known from India, is identified. Parasites of the numerous fishes of the South Pacific have been studied very little and, so far as we can learn, no Monogenea has been reported from this region. One difficulty met in collecting there was lack of adequate identification of the hosts. In these particular cases, only the common or native names of the fishes were obtained. Often, however, the general type of family of the fish was evident

Plasticity in Zebrafish hox Expression in the Hindbrain and Cranial Neural Crest

AbstractThe anterior–posterior identities of cells in the hindbrain and cranial neural crest are thought to be determined by their Hox gene expression status, but how and when cells become committed to these identities remain unclear. Here we address this in zebrafish by cell transplantation, to test plasticity in hox expression in single cells. We transplanted cells alone, or in small groups, between hindbrain rhombomeres or between the neural crest primordia of pharyngeal arches. We found that transplanted cells regulated hox expression according to their new environments. The degree of plasticity, however, depended on both the timing and the size of the transplant. At later stages transplanted cells were more likely to be irreversibly committed and maintain their hox expression, demonstrating a progressive loss of responsiveness to the environmental signals that specify segmental identities. Individual transplanted cells also showed greater plasticity than those lying within the center of larger groups, suggesting that a community effect normally maintains hox expression within segments. We also raised experimental embryos to larval stages to analyze transplanted cells after differentiation and found that neural crest cells contributed to pharyngeal cartilages appropriate to the anterior–posterior level of the new cellular environment. Thus, consistent with models implicating hox expression in control of segmental identity, plasticity in hox expression correlates with plasticity in final cell fate

Results of seed tests for 1915, Bulletin, no. 177

The Bulletin is a publication of the New Hampshire Agricultural Experiment Station, College of Life Sciences and Agriculture, University of New Hampshire, Durham, New Hampshire

Results of seed tests for 1917, Bulletin, no. 186

The Bulletin is a publication of the New Hampshire Agricultural Experiment Station, College of Life Sciences and Agriculture, University of New Hampshire, Durham, New Hampshire

Results of seed tests for 1916, Bulletin, no. 180

The Bulletin is a publication of the New Hampshire Agricultural Experiment Station, College of Life Sciences and Agriculture, University of New Hampshire, Durham, New Hampshire

System development and early biological tests in NASA's biomass production chamber

The Biomass Production Chamber at Kennedy Space Center was constructed to conduct large scale plant growth studies for NASA's CELSS program. Over the past four years, physical systems and computer control software have been continually upgraded and the degree of atmospheric leakage from the chamber has decreased from about 40 to 5 percent of the total volume per day. Early tests conducted with a limited degree of closure showed that total crop (wheat) growth from the best trays was within 80 percent of reported optimal yields for similar light levels. Yields from subsequent tests under more tightly closed conditions have not been as good--up to only 65 percent of optimal yields. Yields appear to have decreased with increasing closure, yet potential problems exist in cultural techniques and further studies are warranted. With the ability to tightly seal the chamber, quantitative data were gathered on CO2 and water exchange rates. Results showed that stand photosynthesis and transpiration reached a peak near 25 days after planting, soon after full vegetative ground cover was established. In the final phase of testing when atmospheric closure was the highest, ethylene gas levels in the chamber rose from about 10 to nearly 120 ppb. Evidence suggests that the ethylene originated from the wheat plants themselves and may have caused an epinastic rolling of the leaves, but no apparent detrimental effects on whole plant function

Three New Long Period X-ray Pulsars Discovered in the Small Magellanic Cloud

The Small Magellanic Cloud is increasingly an invaluable laboratory for studying accreting and isolated X-ray pulsars. We add to the class of compact SMC objects by reporting the discovery of three new long period X-ray pulsars detected with the {\it Chandra X-ray Observatory}. The pulsars, with periods of 152, 304 and 565 seconds, all show hard X-ray spectra over the range from 0.6 - 7.5 keV. The source positions of the three pulsars are consistent with known H-alpha emission sources, indicating they are likely to be Be type X-ray binary star systems.Comment: Accepted for publication in the Astrophysical Journa

Electronic structure study by means of X-ray spectroscopy and theoretical calculations of the "ferric star" single molecule magnet

The electronic structure of the single molecule magnet system M[Fe(L)2]3*4CHCl3 (M=Fe,Cr; L=CH3N(CH2CH2O)2) has been studied using X-ray photoelectron spectroscopy, X-ray absorption spectroscopy, soft X-ray emission spectroscopy, and density functional calculations. There is good agreement between theoretical calculations and experimental data. The valence band mainly consists of three bands between 2 eV and 30 eV. Both theory and experiments show that the top of the valence band is dominated by the hybridization between Fe 3d and O 2p bands. From the shape of the Fe 2p spectra it is argued that Fe in the molecule is most likely in the 2+ charge state. Its neighboring atoms (O,N) exhibit a magnetic polarisation yielding effective spin S=5/2 per iron atom, giving a high spin state molecule with a total S=5 effective spin for the case of M = Fe.Comment: Fig.2 replaced as it will appear in J. Chem. Phy

Bumpy Black Holes in Alternate Theories of Gravity

We generalize the bumpy black hole framework to allow for alternative theory deformations. We construct two model-independent parametric deviations from the Kerr metric: one built from a generalization of the quasi-Kerr and bumpy metrics and one built directly from perturbations of the Kerr spacetime in Lewis-Papapetrou form. We find the conditions that these "bumps" must satisfy for there to exist an approximate second-order Killing tensor so that the perturbed spacetime still possesses three constants of the motion (a deformed energy, angular momentum and Carter constant) and the geodesic equations can be written in first-order form. We map these parameterized metrics to each other via a diffeomorphism and to known analytical black hole solutions in alternative theories of gravity. The parameterized metrics presented here serve as frameworks for the systematic calculation of extreme-mass ratio inspiral waveforms in parameterized non-GR theories and the investigation of the accuracy to which space-borne gravitational wave detectors can constrain such deviations.Comment: 17 pages, replaced with version published in Phys. Rev.

Hard X-ray Imaging Survey of the Galactic Plane with the Caltech Gamma-Ray Imaging Payload GRIP-2

In a recent balloon flight on October 6-7, 1995, the Caltech coded aperture Gamma-Ray Imaging Payload (GRIP-2) imaged numerous fields in the Galactic plane and center in the 25 ke V - 600 ke V energy band. GRIP-2's large phoswich detector (3830 cm2), 15° (FWHM) field of view, 30' angular resolution and 6' point source localization ability make it ideally suited for surveying the accreting binary population of the Galaxy at high energy. We present a brief description of the instrument and we also report preliminary imaging results from our recent Southern hemisphere campaign and show the capabilities of this balloon-borne coded aperture telescope for hard X-ray/gamma ray imaging. Several galactic sources have so far been detected above 25 keV with GRIP-2: IE 1740.7-2942, GRS 1758-258, Cyg X-1, GX 339-4, GX 354-0, GX 1+4, GRS 1915+105, Cyg X-3, 4U 1700-377, 4U 1702-429, Terzan 2 and the Crab pulsar