Bookshelf

Paddy yield for select provinces in the Red River Delta, Vietnam.

When individual cells in the epithelium begin to develop as neural cells, they signal to their neighbors not to do the same. This inhibitory, contact-dependent signaling is mediated by the ligand Delta that appears on the surface of the future nerve cell and binds to Notch proteins on the neighboring cells. In many tissues, all the cells in a cluster initially express Delta and Notch, and a competition occurs, with one cell emerging as winner, expressing Delta strongly and inhibiting its neighbors from doing likewise. In other cases, additional factors interact with Delta or Notch to make some cells susceptible to the lateral inhibition signal and others deaf to it.

Agricultural land loss for selected Pearl River Delta counties, 1990-1996.
SOURCE: Seto, Kaufmann, and Woodcock (2000).

Pattern mixture sensitivity analysis. Left panel: plot of mean outcome among nonrespondents as a function of sensitivity parameter Δ, where Δ = 0 corresponds to MAR. Center panel: plot of full-data mean as function Δ. Right panel: contour of Z statistic for comparing placebo to active treatment, where Δ is varied separately by treatment.

Red River Delta study area. The left inset shows the study area in relation to the country (Vietnam). The right insetis a satellite composite image from the Landsat Thematic Mapper circa 1992.

A,B. Diffuse labeling of the δ subunit is substantially decreased in the molecular layer (arrow in B) of the dentate gyrus (DG) in pilocarpine-treated mice. Less change is evident in CA1 and CA3, where δ subunit expression is normally low. C,D. In contrast, δ subunit labeling of interneurons (arrows) in the molecular layer (M) and along the base of the granule cell layer (G) is increased in pilocarpine-treated animals. Scale bars: A,B, 200 μm; C,D, 40 μm. Adapted from Peng Z, Huang CS, Stell BM, Mody I and Houser CR. Altered expression of the δ subunit of the GABA_A receptor in a mouse model of temporal lobe epilepsy. J. Neurosci. 24:8629–8639, 2004, with permission.

The ATP synthase can either synthesize ATP by harnessing the proton-motive force (top) or pump protons against their electrochemical gradient by hydrolyzing ATP (bottom). As explained in the text, the direction of operation at any given instant depends on the net free-energy change for the coupled processes of H⁺translocation across the membrane and the synthesis of ATP from ADP and P_i.
We have previously shown how the free-energy change (Δ G) for ATP hydrolysis depends on the concentrations of the three reactants ATP, ADP, and P_i (Figure 14-22); the Δ Gfor ATP synthesis is the negative of this value. The Δ G for proton translocation across the membrane is proportional to the proton-motive force. The conversion factor between them is the faraday. Thus, Δ G _H⁺ = -0.023 (proton-motive force), where Δ G _H⁺ is in kilocalories per mole (kcal/mole) and the proton-motive force is in millivolts (mV). For an electrochemical H⁺ gradient of 200 mV, Δ G _H⁺ = -4.6 kcal/mole.

The gray areas give acceptable values (for the 95% confidence level) of parameter combinations aγ and Δ in linear-quadratic fit for all solid-cancer and all leukemia deaths in Hiroshima. ag: linear coefficient, that is, excess relative risk (ERR) per gray at low doses; Δ: 'crossover dose,' which equals ratio of linear and quadratic coefficient in the dose dependence for γ-rays. Diagrams are given for an assumed maximal RBE of neutrons R = 15. Data on solid cancers fit best to large values of Δ, that is, to linear dependence; but Δ = 1Gy cannot be rejected at the 95% confidence level, and this value corresponds to the DDREF = 2 assumed by ICRP. For leukemias, best estimate is obtained for Δ = 0.7 Gy, and this is fully consistent with DDREF =2.

Pearl River Delta study area. The upper left inset shows the Guangdong Province within China; the upper right inset pinpoints the study area in relation to the province; the bottom inset is a satellite composite image of sample data from the Landsat Thematic Mapper circa 1992.

Sinus Rhythm With Short PR Interval and Delta Wave. A 12-lead ECG shows sinus rhythm with a short PR interval and delta wave. Contributed by Intisar Ahmed

Sinus Rhythm With Short PR Interval and Delta Wave. A 12-lead ECG shows sinus rhythm with a short PR interval and delta wave. Contributed by Intisar Ahmed

The leading strand is synthesized by polymerase III (pol III) in E. coli and by polymerase δ (pol δ) in mammalian cells. In E. coli, lagging strand synthesis is initiated by primase, and RNA primers are extended by polymerase III. In mammalian cells, lagging strand synthesis is initiated by a complex of primase with polymerase α (pol α). The short RNA-DNA fragments synthesized by this complex are then extended by polymerase δ.

Scratching response to select pruritogens is drastically reduced in Mrgprcluster Δ^-/- mice. (a, b) Scratching bouts in response to histamine (10 μmol) and the mast cell degranulator Compound 48/80 (100 μg) are comparable in WT and Mrgpr-cluster Δ^-/- mice (n = 12 for each). Substances were administered subcutaneously in the nape of the neck of 2- to 3-month old mice, and scratching bouts were counted for 30 min. (c) Scratching response to CQ (200 μg) was strongly reduced in Mrgpr-cluster Δ^-/- mice (n = 9 for KO, n = 8 for WT). Right panel shows the number of scratches throughout the 30-min examination period. (d) Scratching induced by BAM8-22 (50 nmol) is also strongly reduced in Mrgpr-cluster Δ^-/- mice (n = 8 for each). (e) Scratching in response to SLIGRL-NH2 (100 nmol) was strongly reduced in Mrgpr-cluster Δ^-/- mice (n = 7 for KO, n = 6 for WT). Right panel shows the number of scratches throughout the 30-min examination period. Unlike SLIGRL, SLIGR, the PAR2 specific peptide referenced in Figure 12.4, does not evoke any scratching in neither wild-type nor Mrgpr cluster knockout mice (data not shown). (Sections a to d from Liu, Q. et al., Cell, 139, 1353–1365, 2009. Section e from Liu, Q. et al., Sci. Signal, 4, ra452011, 2011.)

The electron distributions in the polar water molecule (H₂O) and the nonpolar oxygen molecule (O₂) are compared (δ⁺, partial positive charge; δ^-, partial negative charge).

(a) Distribution of delta trail time with respect to dementia severity; (b) distribution of delta trail time with respect to Z-drug use; (c) mean score over NACC visit, stratified by age group; and (d) mean score over NACC visit, stratified by number of visits completed.

Expression of the Delta gene during Xenopus neurulation is found in those cells that are the precursors of the motor, intermediate, and sensory neurons. The expression of Delta distinguishes these neural cells from the presumptive epidermal and glial cells. (From Chitnis et al. 1995; photograph courtesy of C. Kintner.)

Central delta brushes, right rhythmic temporal theta. This is an EEG sample of a 32-week CA baby during sleep. Notice the centrally located delta brushes (delta wave with superimposed alpha beta activity 8 to 20 Hz) and the right temporal theta (brief paroxysmal or independent theta activity in the temporal region that can be sharply contoured but lacks evolution or after-going slow wave). Figure courtesy of Elia M. Pestana-Knight, MD, Cleveland Clinic Foundation.