A rarefaction-tracking method for hyperbolic conservation laws

We present a numerical method for scalar conservation laws in one space dimension. The solution is approximated by local similarity solutions. While many commonly used approaches are based on shocks, the presented method uses rarefaction and compression waves. The solution is represented by particles that carry function values and move according to the method of characteristics. Between two neighboring particles, an interpolation is defined by an analytical similarity solution of the conservation law. An interaction of particles represents a collision of characteristics. The resulting shock is resolved by merging particles so that the total area under the function is conserved. The method is variation diminishing, nevertheless, it has no numerical dissipation away from shocks. Although shocks are not explicitly tracked, they can be located accurately. We present numerical examples, and outline specific applications and extensions of the approach.Comment: 21 pages, 7 figures. Similarity 2008 conference proceeding

Polymorphs and hydrates of acyclovir

Acyclovir (ACV) has been commonly used as an antiviral for decades. Although the crystal structure of the commercial form, a 3:2 ACV/water solvate, has been known since 1980s, investigation into the structure of anhydrous ACV has been limited. Here, we report the characterization of four anhydrous forms of ACV and a new hydrate in addition to the known hydrate. Two of the anhydrous forms appear as small needles and are stable to air exposure, whereas the third form is morphologically similar but quickly absorbs water from the atmosphere and converts back to the commercial form. The high-temperature modification is achieved by heating anhydrous form I above 180°C. The crystal structures of anhydrous form I and a novel hydrate are reported for the first time. © 2010 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 100:949–963, 2011Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/79417/1/22336_ftp.pd

Vote buying or (political) business (cycles) as usual?

We study the short-run effect of elections on monetary aggregates in a sample of 85 low and middle income democracies (1975-2009). We find an increase in the growth rate of M1 during election months of about one tenth of a standard deviation. A similar effect can neither be detected in established OECD democracies nor in other months. The effect is larger in democracies with many poor and uneducated voters, and in Sub-Saharan Africa, Latin America, and in East-Asia and the Pacific. We argue that the election month monetary expansion is related to systemic vote buying which requires significant amounts of cash to be disbursed right before elections. The finely timed increase in M1 is consistent with this; is inconsistent with a monetary cycle aimed at creating an election time boom; and it cannot be, fully, accounted for by alternative explanations