Higher levels of process synchronisation

Four new synchronisation primitives (SEMAPHOREs, RESOURCEs, EVENTs and BUCKETs) were introduced in the KRoC 0.8beta release of occam for SPARC (SunOS/Solaris) and Alpha (OSF/1) UNIX workstations [1][2][3]. This paper reports on the rationale, application and implementation of two of these (SEMAPHOREs and EVENTs). Details on the other two may be found on the web [4]. The new primitives are designed to support higher-level mechanisms of SHARING between parallel processes and give us greater powers of expression. They will also let greater levels of concurrency be safely exploited from future parallel architectures, such as those providing (virtual) shared-memory. They demonstrate that occam is neutral in any debate between the merits of message-passing versus shared-memory parallelism, enabling applications to take advantage of whichever paradigm (or mixture of paradigms) is the most appropriate. The new primitives could be (but are not) implemented in terms of traditional channels, but only at the expense of increased complexity and computational overhead. The primitives are immediately useful even for uni-processors - for example, the cost of a fair ALT can be reduced from O(n) to O(1). In fact, all the operations associated with new primitives have constant space and time complexities; and the constants are very low. The KRoC release provides an Abstract Data Type interface to the primitives. However, direct use of such mechanisms still allows the user to misuse them. They must be used in the ways prescribed (in this paper and in [4]) else their semantics become unpredictable. No tool is provided to check correct usage at this level. The intention is to bind those primitives found to be useful into higher level versions of occam. Some of the primitives (e.g. SEMAPHOREs) may never themselves be made visible in the language, but may be used to implement bindings of higher-level paradigms (such as SHARED channels and BLACKBOARDs). The compiler will perform the relevant usage checking on all new language bindings, closing the security loopholes opened by raw use of the primitives. The paper closes by relating this work with the notions of virtual transputers, microcoded schedulers, object orientation and Java threads

The design and investigation of the self-assembly of dimers with two nematic phases

A series of non-symmetric dimers were synthesised containing either cyanobiphenyl or difluoroterphenyl moieties on one side and a range of long, short, bent, polar or apolar mesogens on the other side of the molecules. The dielectric anisotropy of the mesogens was varied systematically. The systems were characterised by differential scanning calorimetry (DSC), optical polarizing microscopy (OPM) and detailed X-ray diffraction (XRD) studies, both in the nematic and the Nx phase. The results are compared and structure properties relationships are discussed. A model for the assembly in the Nx phase is developed discussing Ntb structures, coaxial helices, swiss roll structures and chiral domain formation

Understanding Latin American currency pegs to the dollar

Latin America ; Dollar, American

Banking and currency crisis recovery: Brazil's turnaround of 1999

Of the many countries that suffered exchange rate crises in the 1990s, Brazil and Korea recovered most rapidly. This article analyzes the Brazilian recovery. William Gruben and John Welch focus on the freedom that Brazilian bank health gave to the central bank to pursue a postcrisis monetary policy that would settle markets, reestablish price stability, and encourage investment and the return of foreign capital. Brazilian bank health was not an accident; it reflected not only bank responses to precrisis changes in government regulations, but also to large precrisis interest rate increases associated in part with Brazil's efforts to defend its currency.Banks and banking - Brazil

Interpreting central bank independence in Mexico

Banks and banking, Central ; Mexico

Is NAFTA economic integration?

Most economists agree that trade liberalization raises incomes and living standards. To achieve trade liberalization, though, countries must sometimes first reach trade agreements. And trade agreements, as William Gruben and John Welch observe, may intertwine elements of both liberalization and protectionism. As an example, Gruben and Welch examine the negotiation process that preceded passage of the North American Free Trade Agreement. ; Is NAFTA economic integration? Although some authors think so, Gruben and Welch believe that interpreting NAFTA purely as economic integration is misleading. A more useful way to interpret NAFTA, they claim, is to start by recognizing it as the latest synthesis of an ongoing conflict between those who support trade liberalization and those who want trade protectionism. NAFTA offers broad-based trade openings, but it still contains restrictively protectionist components. In considering the efforts of trade liberalization advocates and trade protectionists, the authors also attempt to show how members of these pressure groups form alliances, disguise their efforts, and otherwise attempt to achieve their goals.North American Free Trade Agreement

Is tighter fiscal policy expansionary under fiscal dominance? Hypercrowding out in Latin America

We test for hypercrowding out as a signal of market concerns over fiscal dominance in five Latin American countries. Hypercrowding out occurs when fiscally dominated governments’ domestic credit demands are perceived as so intrusive to a nation’s financial system that a move towards fiscal surplus lowers interest rates and increases growth. We sample five Latin American countries to test for these relationships. Judged by the results of vector error correction models, three nations test clearly positive, suggesting market concern despite their recent efforts towards fiscal balance.

Default risk, dollarization, and currency substitution in Mexico

Money ; Mexico

Applications of remote sensing to estuarine management

Projects for sewage outfall siting for pollution control in the lower Chesapeake Bay wetlands are reported. A dye-buoy/photogrammetry and remote sensing technique was employed to gather circulation data used in outfall siting. This technique is greatly favored over alternate methods because it is inexpensive, produces results quickly, and reveals Lagrangian current paths which are preferred in making siting decisions. Wetlands data were obtained by interpretation of color and color infrared photographic imagery from several altitudes. Historical sequences of photographs are shown that were used to document wetlands changes. Sequential infrared photography of inlet basins was employed to determine tidal prisms, which were input to mathematical models to be used by state agencies in pollution control. A direct and crucial link between remote sensing and management decisions was demonstrated in the various projects

U.S. banks, competition, and the Mexican banking system: how much will NAFTA matter?

Bank competition ; North American Free Trade Agreement ; Mexico