SEM Studies on Vessels in Ferns. 18. Montane Cheilanthoid Ferns (Pteridaceae) of North America

Xylem of roots and rhizomes of five species of four genera of tribe Cheilantheae (Pteridaceae; recently recognized by some as a segregate family, Cheilanthaceae) has been studied by means of scanning electron microscopy (SEM). All of these species occur in habitats (cliffs, talus) of mountains of North America that are seasonally dry in summer and cold in winter. The vessels prove diverse, indicating that different perforation plate modifications are represented in the cheilanthoid ferns of these habitats, rather than different degrees of the same kind of modification. The modifications include wide perforations alternating with narrow perforations (especially prominent in Bommeria); discontinuous perforation plates (Cheilanthes, Pellaea); and narrow, slitlike perforations (Cheilanthes). The discontinuous perforation plates are newly reported for ferns. The exceptionally prominent perforations of Bommeria vessels may be correlated with greater laminar surface and higher transpiration during wet periods in that genus; the other genera have small laminae with probable low transpiration rates even during moist periods

The Effect of Upper Extremity Immobilization Following Surgical Rotator Cuff Repair on Balance in Elderly Individuals

The purpose of this study was to determine if a relationship exists between upper extremity immobilization following surgical rotator cuff repair and balance in elderly individuals. Twenty-eight healthy volunteers (nine with rotator cuff repair, nineteen without) aged 53 to 74 participated in the study. Balance was measured using the Berg Balance Measure, Modified Berg Balance Measure, Functional Reach Test, and force plate analysis. Results were analyzed using t-tests for paired and independent samples, Mann Whitney U (Wilcoxon Rank Sum W) tests and Wilcoxon Matched-Pairs Signed- Ranks tests. Significant differences were found between the post-rotator cuff surgery and control groups for performance on the Berg (p=0.0125) and Modified Berg (p=0.019, p=0.0120), as well as between the sling and no-sling block for two measures of posterior maximal lean (p=0.0249, p=0.0179). Results suggest that long and short term immobilization have some effect on balance. A need for balance training may exist in this population

The Riparian Vegetation of Swauk Creek

An investigation was made to document the structure and composition of the flora along Swauk Creek, a riparian transect into Central Washington\u27s Cascade Range. Distributions of the major species are discussed and a key has been constructed to facilitate identification of the riparian associations

Directions futures dans ta recherche du vieillissement : La nécessité de vaincre les maladies du vieillissement

Les affections du vieillissement ; Prévenir les affections du vieillissement et augmenter l'intervalle de sant

Schwarzschild horizon and the gravitational redshift formula

The gravitational redshift formula is usually derived in the geometric optics approximation. In this note we consider an exact formulation of the problem in the Schwarzschild space-time, with the intention to clarify under what conditions this redshift law is valid. It is shown that in the case of shocks the radial component of the Poynting vector can scale according to the redshift formula, under a suitable condition. If that condition is not satisfied, then the effect of the backscattering can lead to significant modifications. The obtained results imply that the energy flux of the short wavelength radiation obeys the standard gravitational redshift formula while the energy flux of long waves can scale differently, with redshifts being dependent on the frequency.Comment: Revtex, 5 p. Rewritten Sec. II, minor changes in Secs III - VII. To appear in the Classical and Quantum Gravit

Cloning of rat GADD45 gene and induction analysis following ionizing radiation in vivo

AbstractA gene encoded GADD45 was isolated from rat and revealed four exons along with a p53 binding consensus sequence and a putative AP-1 site in the third intron. This suggests that the rat GADD45 gene is also involved in the p53 signal pathway related to the G1 cell cycle checkpoint. The rat GADD45 mRNA was induced within 30 min in liver and increased as a function of γ-irradiation. We found that mRNA expression differed substantially in a variety of tissues (brain, liver, kidney, and spleen). The finding of in vivo induction of GADD45 gene may provide insight into the role of GADD45 gene in DNA repair

Hubble Space Telescope Spectroscopy of Brown Dwarfs Discovered with the Wide-field Infrared Survey Explorer

We present a sample of brown dwarfs identified with the {\it Wide-field Infrared Survey Explorer} (WISE) for which we have obtained {\it Hubble Space Telescope} ({\it HST}) Wide Field Camera 3 (WFC3) near-infrared grism spectroscopy. The sample (twenty-two in total) was observed with the G141 grism covering 1.10$-$1.70 $\mu$m, while fifteen were also observed with the G102 grism, which covers 0.90$-$1.10 $\mu$m. The additional wavelength coverage provided by the G102 grism allows us to 1) search for spectroscopic features predicted to emerge at low effective temperatures (e.g.\ ammonia bands) and 2) construct a smooth spectral sequence across the T/Y boundary. We find no evidence of absorption due to ammonia in the G102 spectra. Six of these brown dwarfs are new discoveries, three of which are found to have spectral types of T8 or T9. The remaining three, WISE J082507.35$+$280548.5 (Y0.5), WISE J120604.38$+$840110.6 (Y0), and WISE J235402.77$+$024015.0 (Y1) are the nineteenth, twentieth, and twenty-first spectroscopically confirmed Y dwarfs to date. We also present {\it HST} grism spectroscopy and reevaluate the spectral types of five brown dwarfs for which spectral types have been determined previously using other instruments.Comment: Accepted for publication in the Astrophysical Journal. 20 pages, 18 figures, 7 table

Do tracheid microstructure and the presence of minute crystals link Nymphaeaceae, Cabombaceae and Hydatellaceae?

Original scanning electron microscopy (SEM) observations are presented for stems of Brasenia schreberi and Cabomba caroliniana of Cabombaceae and three species of Trithuria of Hydatellaceae. End walls of stem tracheids of Brasenia have the same peculiar microstructure that we have reported in Barclaya, Euryale, Nuphar, Nymphaea (including Ondinea) and Victoria of Nymphaeaceae. This feature unites Cabombaceae with Nymphaeaceae. The minute rhomboidal crystals on the surfaces of stellate parenchyma cells of Brasenia reported by Solereder (1906. Oxford: University Press), but not noticed since, are figured. They are like the minute crystals of the often-mentioned astrosclereids of Nymphaeaceae. Neither of these two features has been observed in Hydatellaceae. If the absence of these two features can be confirmed, the reason may be more related to ecology, development, habit and anatomical organization than to degree of phylogenetic relationship as shown by molecular studies. Anatomical observations on the stem anatomy of Trithuria are offered on the basis of paraffin sections prepared for a paper b