Spatial-Temporal Association of Duration of Peak Period at Signalized Intersections

In the case of peak spreading, the traditional static analysis on the duration of congestion using peak 15 minutes of hour has lost its meaning. To deal with congestion, we need dynamic analysis on the onset and dissipation of congestion. This paper aims to reflect the severity of congestion, even the spatial interaction of congestion, by the relative size of peak period. Two thresholds, the minimum value in the peak hour and 95 percent of peak hour volume respectively, were chosen to define the peak using archived stop-bar detector data. The thresholds and the time-granularity of the data were cross-compared to choose appropriate threshold and data time interval, and the result is 95 percent of peak hour volume under 10min interval data. Then the measures of duration of peak period, including the length of peak period, the beginning and ending time of peak period, were calculated for different signalized intersections inlet approaches. Further, the measures of peak period of different intersections in the same direction of the same radial road were presented to find out the commute traffic patterns. Lastly, the spatial-temporal association pattern of the measures of peak period of different intersections in downtown Shanghai was performed by ArcGIS.

Mitotic phosphorylation of SUV39H1, a novel component of active centromeres, coincides with transient accumulation at mammalian centromeres

Centromeres of eukaryotes are frequently associated with constitutive heterochromatin and their activity appears to be coregulated by epigenetic modification of higher order chromatin. Recently, we isolated murine (Suv39h1) and human (SUV39H1) homologues of the dominant Drosophila suppressor of position effect variegation Su(var)3-9, which is also related to the S. pombe silencing factor Clr4. We have shown that mammalian Su(var)3-9 homologues encode novel centromeric proteins on metaphase-arrested chromosomes. Here, we describe a detailed analysis of the chromatin distribution of human SUV39H1 during the cell cycle. Although there is significant heterochromatic overlap between SUV39H1 and M31 (HP1(beta)) during interphase, mitotic SUV39H1 displays a more restricted spatial and temporal association pattern with metaphase chromosomes than M31 (HP1(beta)), or the related HP1(α) gene product. SUV39H1 specifically accumulates at the centromere during prometaphase but dissociates from centromeric positions at the meta- to anaphase transition. In addition, SUV39H1 selectively associates with the active centromere of a dicentric chromosome and also with a neocentromere. Interestingly, SUV39H1 is shown to be a phosphoprotein with modifications at serine and, to a lesser degree, also at threonine residues. Whereas SUV39H1 steady-state protein levels appear constant during the cell cycle, two additional phosphorylated isoforms are detected in mitotic extracts. This intriguing localisation and modification pattern would be consistent with a regulatory role(s) for SUV39H1 in participating in higher order chromatin organisation at mammalian centromeres.