Acceleration of phenological advance and warming with latitude over the past century.

In the Northern Hemisphere, springtime events are frequently reported as advancing more rapidly at higher latitudes, presumably due to an acceleration of warming with latitude. However, this assumption has not been investigated in an analytical framework that simultaneously examines acceleration of warming with latitude while accounting for variation in phenological time series characteristics that might also co-vary with latitude. We analyzed 743 phenological trend estimates spanning 86 years and 42.6 degrees of latitude in the Northern Hemisphere, as well as rates of Northern Hemisphere warming over the same period and latitudinal range. We detected significant patterns of co-variation in phenological time series characteristics that may confound estimates of the magnitude of variation in trends with latitude. Notably, shorter and more recent time series tended to produce the strongest phenological trends, and these also tended to be from higher latitude studies. However, accounting for such variation only slightly modified the relationship between rates of phenological advance and latitude, which was highly significant. Furthermore, warming has increased non-linearly with latitude over the past several decades, most strongly since 1998 and northward of 59°N latitude. The acceleration of warming with latitude has likely contributed to an acceleration of phenological advance along the same gradient

Some Chemical Differences Between Artificially Produced Parthenocarpic Fruits And Normal Seeded Fruits Of Tomato

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/141236/1/ajb210988.pd

Logistic Barriers to U.S.–Mexico Grain and Soybean Trade

Fourteen years after the implementation of the North American Free Trade Agreement (NAFTA), border-crossing restrictions still remain with Mexico. Although studies have analyzed the impact of NAFTA trade liberalization, there has only been limited research on effects of informal trade barriers on U.S.–Mexico grain and soybean flows. This paper quantitatively measures the impact of logistic barriers impeding U.S.–Mexico grain and soybean trade. A conditional model testing for the presence of asymmetries in grain trade suggests that logistic barriers and transshipments are correlated. Econometric analysis rejects the null hypoInternational Relations/Trade,

The Value of Iowa School District Community Demographic Data in Explaining School District ITBS/ITED 3rd and 11th Grade Language Arts and Mathematics Scores

The purpose of this study was to determine which combination of 15 community demographic factors account for the most amount of variance and can best predict an Iowa school district’s percentage of students scoring proficient or above on the 2010 Iowa Test of Basic Skills (ITBS) and Iowa Test of Educational Development (ITED) for 3rd and 11th grade Language Arts and Mathematics. This study, along with extant literature and past research, supports the hypothesis that community demographic factors have an impact on state standardized test scores. This study revealed that 20.4% of the variance in 2010 ITBS 3rd grade Language Arts scores can be explained by community demographic variables; 12.2% of the variance in 2010 ITBS 3rd grade Mathematics scores can be explained by community demographic variables; 20.3% of the variance in 2010 ITED 11th grade Language Arts scores can be explained by community demographic variables; 23.6% of the variance in 2010 ITED 11th grade Mathematics scores can be explained by community demographic variables. Using only community demographic factors, this study successfully predicted as much as 73% (11th grade Language Arts) of the actual 2010 ITBS/ITED scores and as much as 69% (11th grade Mathematics) of the actual 2010 ITBS/ITED scores. The results of this study add to the growing body of research that community demographic factors influence student achievement results