The Rapid Update Cycle (RUC), an operational regional analysis-forecast system among the suite of models at the National Centers for Environmental Prediction (NCEP), is distinctive in two primary aspects: its hourly assimilation cycle and its use of a hybrid isentropic-sigma vertical coordinate. The use of a quasi-isentropic coordinate for the analysis increment allows the influence of observations to be adaptively shaped by the potential temperature structure around the observation, while the hourly update cycle allows for a very current analysis and short-range forecast. Herein, the RUC analysis framework in the hybrid coordinate is described, and some considerations for high-frequency cycling are discussed. A 20-km 50-level hourly version of the RUC was implemented into operations at NCEP in April 2002. This followed an initial implementation with 60-km horizontal grid spacing and a 3-h cycle in 1994 and a major upgrade including 40-km horizontal grid spacing in 1998. Verification of forecasts from the latest 20-km version is presented using rawinsonde and surface observations. These verification statistics show that the hourly RUC assimilation cycle improves short-range forecasts (compared to longer-range forecasts valid at the same time) even down to the 1-h projection.

Visual processing deficits are an integral component of schizophrenia and are sensitive predictors of schizophrenic decompensation in healthy adults. The primate visual system consists of discrete subcortical magnocellular and parvocellular pathways, which project preferentially to dorsal and ventral cortical streams. Subcortical systems show differential stimulus sensitivity, while cortical systems, in turn, can be differentiated using surface potential analysis. The present study examined contributions of subcortical dysfunction to cortical processing deficits using high-density event-related potentials. Event-related potentials were recorded to stimuli biased towards the magnocellular system using low-contrast isolated checks in Experiment 1 and towards the magnocellular or parvocellular system using low versus high spatial frequency (HSF) sinusoidal gratings, respectively, in Experiment 2. The sample consisted of 23 patients with schizophrenia or schizoaffective disorder and 19 non-psychiatric volunteers of similar age. In Experiment 1, a large decrease in the P1 component of the visual event-related potential in response to magnocellular-biased isolated check stimuli was seen in patients compared with controls (F = 13.2, P = 0.001). Patients also showed decreased slope of the contrast response function over the magnocellular-selective contrast range compared with controls (t = 9.2, P = 0.04) indicating decreased signal amplification. In Experiment 2, C1 (F = 8.5, P = 0.007), P1 (F = 33.1, P < 0.001) and N1 (F = 60.8, P < 0.001) were reduced in amplitude to magnocellular-biased low spatial frequency (LSF) stimuli in patients with schizophrenia, but were intact to parvocellular-biased HSF stimuli, regardless of generator location. Source waveforms derived from inverse dipole modelling showed reduced P1 in Experiment 1 and reduced C1, P1 and N1 to LSF stimuli in Experiment 2, consistent with surface waveforms. These results indicate pervasive magnocellular dysfunction at the subcortical level that leads to secondary impairment in activation of cortical visual structures within dorsal and ventral stream visual pathways. Our finding of early visual dysfunction is consistent with and explanatory of classic literature showing subjective complaints of visual distortions and is consistent with early visual processing deficits reported in schizophrenia. Although deficits in visual processing have frequently been construed as resulting from failures of top-down processing, the present findings argue strongly for bottom-up rather than top-down dysfunction at least within the early visual pathway. Deficits in magnocellular processing in this task may reflect more general impairments in neuronal systems functioning, such as deficits in non-linear amplification and may thus represent an organizing principle for predicting neurocognitive dysfunction in schizophrenia.

Background-The efficacy of nitroglycerin (NTG) as a vasodilator is limited by tolerance, which develops shortly after treatment begins. In vascular smooth muscle cells (VSMCs), NTG is denitrated to form nitric oxide (NO), which activates guanylyl cyclase and generates cGMP. cGMP plays a key role in nitrate-induced vasodilation by reducing intracellular Ca 2ϩ concentration. Therefore, one possible mechanism for development of nitrate tolerance would be increased activity of the cGMP phosphodiesterase (PDE), which decreases cGMP levels. Methods and Results-To test this hypothesis, rats were made tolerant by continuous infusion of NTG for 3 days (10 g · kg Ϫ1 · min Ϫ1 SC) with an osmotic pump. Analysis of PDE activities showed an increased function of Ca 2ϩ /calmodulin (CaM)-stimulated PDE (PDE1A1), which preferentially hydrolyzes cGMP after NTG treatment. Western blot analysis for the Ca 2ϩ /CaM-stimulated PDE revealed that PDE1A1 was increased 2.3-fold in NTG-tolerant rat aortas. Increased PDE1A1 was due to mRNA upregulation as measured by relative quantitative reverse transcription-polymerase chain reaction. The PDE1-specific inhibitor vinpocetine partially restored the sensitivity of the tolerant vasculature to subsequent NTG exposure. In cultured rat aortic VSMCs, angiotensin II (Ang II) increased PDE1A1 activity, and vinpocetine blocked the effect of Ang II on decrease in cGMP accumulation. Conclusions-Induction of PDE1A1 in nitrate-tolerant vessels may be one mechanism by which NO/cGMP-mediated vasodilation is desensitized and Ca 2ϩ -mediated vasoconstriction is supersensitized. Inhibiting PDE1A1 expression and/or activity could be a novel therapeutic approach to limit nitrate tolerance.

Abstract. We study Einstein warped product spaces. As a result, we prove the following: if M is an Einstein warped product space with nonpositive scalar curvature and compact base, then M is simply a Riemannian product space.

Abstract. A coupled atmospheric/land-surface model covering the conterminous UnitedStates with an associated 1-hour atmospheric data assimilation cycle, the Mesoscale Analysis and Prediction System (MAPS), has been improved to include a snow accumulation/melting scheme and also parameterization of processes in frozen soil. The new aspects of the land-surface model are described in this paper, along with detailed one-dimensional (l-D) tests using an 18-year observation data set from Valday, Russia. These tests show that the MAPS 1-D soil/vegetation/snow model is capable of providing accurate simulations over multiyear periods at locations with significant snow cover and frozen soil. A statistical analysis of the tests shows the expected improvement in snow depth, skin temperature, and especially in runoff from inclusion of these additional surface processes during the spring melting season. This performance in 1-D tests is a necessary prerequisite for robust long-term behavior of soil temperature and moisture fields and other components of the hydrological cycle in the 3-D MAPS coupled assimilation cycle. For GCIP a key question is the degree to which a coupled atmospheric/land-surface model, constrained by hourly assimilation of atmospheric observations to follow the evolution of the atmosphere accurately, can provide a realistic evolution of hydrological fields and time-varying soil fields that are not observed over large areas. A prerequisite for success is that the soil/vegetation/snow component of the coupled model, which is constrained only by atmospheric boundary conditions and definition of fields such as vegetation type and fraction and soil type, must be sufficiently robust to avoid drift over long periods of time. The land surface component of this model must also account for cold-season processes important in middle and 4077

Id1 is an inhibitor of a group of basic helix-loop-helix transcription factors, collectively called E proteins, which includes E12, E47, E2-2, and HEB. We have generated transgenic mice in which Id1 is specifically expressed in T cells. The total number of thymocytes in these mice is less than 4% of that in wild-type mice. The majority of the transgenic thymocytes are CD4 and CD8 double negative and bear the cell surface markers of multipotent progenitor cells. A small number of thymocytes, however, differentiate into CD4 or CD8 single-positive T cells, which also display different characteristics from their wild-type counterparts. More importantly, apoptotic cells constitute about 50% of the total thymocytes. These apoptotic thymocytes have rearranged their T-cell receptor genes, suggesting that they are differentiating T cells. This finding has raised the possibility that the T-cell deficiency in Id1 transgenic mice is the result of a massive apoptosis of differentiating T cells triggered by Id1 expression as opposed to a developmental block at the earliest progenitor stage. The progenitor cells accumulated in the transgenic mice might have survived because they are not susceptible to the apoptotic signals. Despite the massive cell death of the thymocytes at young ages, Id1 transgenic mice frequently develop T-cell lymphoma later in their life span, and lymphomagenesis appears to occur at different stages of T-cell development. Taken together, our data suggest that E proteins, being the targets of Id1, are essential regulators for normal T-cell differentiation and tumor suppression.

Patients with schizophrenia show impairments in motion processing, along with deficits in lower level processing primarily involving the magnocellular visual pathway. The present study investigates potential magnocellular contributions to impaired motion processing in schizophrenia using a combined neurophysiological and behavioral approach. As compared to prior motion studies in schizophrenia, thresholds were determined for both incoherent and coherent visual motion. In this study, velocity discrimination thresholds were measured for schizophrenia patients (n = 14) and agematched normal control subjects (n = 16) using a staircase procedure. Early visual processing was evaluated using steady-state visual evoked potentials (ssVEP), with stimuli biased toward activation of either the magnocellular or parvocellular visual pathways through luminance contrast manipulation. Patients with schizophrenia showed poor velocity discrimination for both incoherent and coherent motion, with no significant group × task interaction. Further, when coherent motion performance was measured at individually determined incoherent motion thresholds, accuracy levels for patients were similar to controls, also indicating similarity of deficit for incoherent vs. coherent motion discrimination. Impairments in velocity discrimination correlated significantly with reduced amplitude of ssVEP elicited by magnocellular -but not parvocellular -selective stimuli. This study demonstrates that deficits in motion processing in schizophrenia are significantly related to reduced activation of the magnocellular visual system. Further, this study supports and extends prior reports of impaired motion processing in schizophrenia, and indicates significant bottom-up contributions to higher-order cognitive impairments.

IVUS-guided DES implantation is associated with significantly lower rates of adverse clinical events compared with angiography guidance. Further study is needed to clarify which subgroups of subjects with IVUS guidance will have greater benefit.