Untitled

Abstract

Overnight low-temperature exposure inhibits photosynthesis in chilling-sensitive species, such as tomato and cucumber, by as much as 60%. Earlier work showed that low temperature stalled the endogenous rhythm controlling transcription of certain nuclear-encoded genes in chilling-sensitive plants causing the synthesis of the corresponding transcripts and proteins to be mistimed upon rewarming. The activity of nitrate reductase (NR), the first and rate-limiting step in the assimilation of nitrate into amino acids in leaves, is subjected to a varied range of regulatory influences including a robust circadian rhythm. We show here that although NR regulation is disrupted by low temperatures, the change is transient and does not alter the phase of the NR endogenous rhythm following the chill. There is a temporary induction of de novo transcription of NR causing an increase in both NR protein and activity. This occurs regardless of the time in the circadian cycle that the chilling episode is initiated thereby decoupling the normally closely coordinated processes of carbon and nitrogen assimilation. This decoupling would be expected to deplete cellular reductant and carbon skeleton reserves as well as allow accumulation of cytotoxic intermediates of nitrogen assimilation thereby contributing to the low temperature induced disruption of metabolism that takes place in photosynthetic cells of chilling sensitive plant species.

Nonlinear density fluctuation field theory for large scale structure

“…It is found that the nonlinear term −b(ξ ′ ) 2 has the effects of strongly enhancing ξ(r) on small scales, and making P (k) flatter in k < k 0 . The friction term aξ ′ has the following effects: slightly increasing the height of ξ(r) on small scales; moving the zeros of ξ(r) to larger r; strongly damping the amplitude of oscillations of ξ on large scales [4,37,12,13,14,35], as seen in FIG.7; smoothing out the sharp peak of P (k) at k 0 and turning P (k) positive for k < k 0 . The main conclusion of this paper is the following.…”

“…where n is the spatial number density. This result qualitatively explains several observed features, such as a stronger correlation for more massive galaxies, galaxies with a smaller n having a higher P (k) [10,14], the scaling of "correlation length" r 0 with the mean cluster separation d as r 0 (d) ∝ d 0.3∼0.5 [1,2,8,17,41], and damped oscillations of ξ c (r) for clusters with a wave-length 2π/k 0 ≃ 120 h −1 Mpc [4,12,13,14,37,35]. Here one sees the physical meaning of the sound speed c s .…”

Non-linear stochastic galaxy biasing in cosmological simulations

“…It is also fairly well established that red galaxies are generally more clustered than the blue population (Landy, Szalay & Koo 1996; Tucker et al 1997), but a quantitative comparison is more difficult, because most of the values in the literature are obtained from the angular or redshift space correlation functions, and a variety of colour bands are used. Willmer et al (1998) quote a relative variance bias in real space at 8 h −1 Mpc, and suggest that there is evidence for scale dependence in the relative bias.…”

Recent Advances in Large-Scale Structure and Galaxy Formation Studies

“…The SDSS LRG sample will also be useful to verify the presence of baryonic features, in P (k), due to oscillations in the baryonic component within the last-scattering surface [42]. A possible detection has been claimed in an analysis of some [56] and SDSS [57] data, compared to the previous Las Campanas Redshift Survey [58]. The dotted lines show instead a correlation function in real space, obtained through deprojection from the APM 2D galaxy catalogue [59] under two different assumptions about galaxy clustering evolution.…”

“…Fig. 4 shows the correlation function measured in redshift space, ξ(s) (see next section for definitions), from the 2dF and SDSS current data sets [56,57], compared to the previous LCRS [58]. Also shown (dotted lines) is ξ(r) reconstructed from the APM angular survey [59].…”