Word Generation in Boston Public Schools: Natural History of a Literacy Intervention

Describes a program to teach high-frequency academic vocabulary and discourses skills, promote effective teaching strategies for vocabulary, comprehension, and discussion, and facilitate faculty collaboration; its implementation; and evaluation results

Two Flaws In Business Cycle Accounting

Using 'business cycle accounting' (BCA), Chari, Kehoe and McGrattan (2006) (CKM) conclude that models of financial frictions which create a wedge in the intertemporal Euler equation are not promising avenues for modeling business cycle dynamics. There are two reasons that this conclusion is not warranted. First, small changes in the implementation of BCA overturn CKM's conclusions. Second, one way that shocks to the intertemporal wedge impact on the economy is by their spillover effects onto other wedges. This potentially important mechanism for the transmission of intertemporal wedge shocks is not identified under BCA. CKM potentially understate the importance of these shocks by adopting the extreme position that spillover effects are zero.

Two flaws in business cycle dating

Using “business cycle accounting,” Chari, Kehoe, and McGrattan (2006) conclude that models of financial frictions which create a wedge in the intertemporal Euler equation are not promising avenues for modeling business cycle dynamics. There are two reasons that this conclusion is not warranted. First, small changes in the implementation of business cycle accounting overturn Chari, Kehoe, and McGrattan’s conclusions. Second, one way that shocks to the intertemporal wedge affect the economy is by their spillover effects onto other wedges. This potentially important mechanism for the transmission of intertemporal-wedge shocks is not identified under business cycle accounting. Chari, Kehoe, and McGrattan potentially understate the importance of these shocks by adopting the extreme position that spillover effects are zero.Business cycles

ON THE USE OF NATURAL-MODE BASIS FUNCTIONS FOR ELECTROMAGNETIC ANALYSIS OF ARBITRARY CONDUCTING SURFACES

The natural modes defined in the singularity expansion method (SEM) are used as basis functions for the frequency- and time-domain current responses of arbitrary perfect electrically conducting (PEC) surfaces in this work. First, a method of determining the natural frequencies and corresponding modes which employs the electric field integral equation is presented. These quantities are then calculated for several geometries and the currents induced due to an incident plane wave in the frequency and time domains are approximated by a weighted sum of the natural modes. Additionally, the modal weights prescribed by SEM are compared to a set of weights obtained through a least-squares (LS) fit. Lastly, the ability of natural modes to represent the currents due to a delta-gap antenna feed is considered

The Weak Scale from BBN

The measured values of the weak scale, $v$, and the first generation masses, $m_{u,d,e}$, are simultaneously explained in the multiverse, with all these parameters scanning independently. At the same time, several remarkable coincidences are understood. Small variations in these parameters away from their measured values lead to the instability of hydrogen, the instability of heavy nuclei, and either a hydrogen or a helium dominated universe from Big Bang Nucleosynthesis. In the 4d parameter space of $(m_u,m_d,m_e,v)$, catastrophic boundaries are reached by separately increasing each parameter above its measured value by a factor of $(1.4,1.3,2.5,\sim5)$, respectively. The fine-tuning problem of the weak scale in the Standard Model is solved: as $v$ is increased beyond the observed value, it is impossible to maintain a significant cosmological hydrogen abundance for any values of $m_{u,d,e}$ that yield both hydrogen and heavy nuclei stability. For very large values of $v$ a new regime is entered where weak interactions freeze out before the QCD phase transition. The helium abundance becomes independent of $v$ and is determined by the cosmic baryon and lepton asymmetries. To maintain our explanation of $v$ from the anthropic cost of helium dominance then requires universes with such large $v$ to be rare in the multiverse. Implications of this are explored, including the possibility that new physics below 10 TeV cuts off the fine-tuning in $v$.Comment: 26 pages plus appendix, 13 figure

Characterizing the spatial determinants and prevention of malaria in Kenya

The United Nations' Sustainable Development Goal 3 is to ensure health and well-being for all at all ages with a specific target to end malaria by 2030. Aligned with this goal, the primary objective of this study is to determine the effectiveness of utilizing local spatial variations to uncover the statistical relationships between malaria incidence rate and environmental and behavioral factors across the counties of Kenya. Two data sources are used-Kenya Demographic and Health Surveys of 2000, 2005, 2010, and 2015, and the national Malaria Indicator Survey of 2015. The spatial analysis shows clustering of counties with high malaria incidence rate, or hot spots, in the Lake Victoria region and the east coastal area around Mombasa; there are significant clusters of counties with low incidence rate, or cold spot areas in Nairobi. We apply an analysis technique, geographically weighted regression, that helps to better model how environmental and social determinants are related to malaria incidence rate while accounting for the confounding effects of spatial non-stationarity. Some general patterns persist over the four years of observation. We establish that variables including rainfall, proximity to water, vegetation, and population density, show differential impacts on the incidence of malaria in Kenya. The El-Nino-southern oscillation (ENSO) event in 2015 was significant in driving up malaria in the southern region of Lake Victoria compared with prior time-periods. The applied spatial multivariate clustering analysis indicates the significance of social and behavioral survey responses. This study can help build a better spatially explicit predictive model for malaria in Kenya capturing the role and spatial distribution of environmental, social, behavioral, and other characteristics of the households.Published versio

Polynomial Wolff axioms and Kakeya-type estimates in R4

We establish new linear and trilinear bounds for collections of tubes in R4 that satisfy the polynomial Wolff axioms. In brief, a collection of δ-tubes satisfies the Wolff axioms if not too many tubes can be contained in the δ-neighborhood of a plane. A collection of tubes satisfies the polynomial Wolff axioms if not too many tubes can be contained in the δ-neighborhood of a low degree algebraic variety. First, we prove that if a set of δ-3 tubes in R4 satisfies the polynomial Wolff axioms, then the union of the tubes must have volume at least δ1-1/28. We also prove a more technical statement which is analogous to a maximal function estimate at dimension 3+1/28. Second, we prove that if a collection of δ-3 tubes in R4 satisfies the polynomial Wolff axioms, and if most triples of intersecting tubes point in three linearly independent directions, then the union of the tubes must have volume at least δ3/4. Again, we also prove a slightly more technical statement which is analogous to a maximal function estimate at dimension 3+1/4. We conjecture that every Kakeya set satisfies the polynomial Wolff axioms, but we are unable to prove this. If our conjecture is correct, it implies a Kakeya maximal function estimate at dimension 3+1/28, and in particular this implies that every Kakeya set in R4 must have Hausdorff dimension at least 3+1/28. This would be an improvement over the current best bound of 3, which was established by Wolff in 1995

1863-05-18 Chamberlain writes to John Hodsdon regarding monthly returns

https://digitalmaine.com/chamberlain_corr/1036/thumbnail.jp