Carbon and oxygen stable isotopes in the Toa Baja Well, Puerto Rico: implications for burial diagenesis and hydrocarbon generation

This is the publisher's version, also available electronically from "http://onlinelibrary.wiley.com".The Toa Baja Well was drilled on the coastal plains of northern Puerto Rico with a total depth of 2705 m [Larue, 1990]. Interstratified limestone, quartz-bearing calcareous sandstones, and shales dominate the uppermost 580 m and are separated from underlying rocks by an unconformity. Below this unconformity continuing to total depth, lithologies encountered consist of volcaniclastic sandstones/siltstones, pelagic carbonates, volcanic flows and either plutonic rocks or coarse-grained immature sandstones derived from plutonic bodies. Stable isotopic data of carbonates suggest diagenetic modification under a meteoric and meteoric-marine mixing environments for sediments above 915 m. A fracture zone near 915 m coincides with an abrupt shift in δ18O compositions indicating the presence of hotter fluids during alteration of these sediments. The depleted δ13C signatures occurring above a fault at 1220 m are suggestive of isotopically light gaseous hydrocarbons migrating through the fault and being oxidized as they dispersed through the sediment column. The abrupt shift in δ18O compositions and its coincidence with the fracture zone at 915 m suggest geopressuring and thermal buildup due to accumulation of hotter, upward migrating formational fluids. Estimated burial temperatures for the interval above 915 m do not exceed 40°C and are possibly lower due to circulating colder meteoric fluids. Maximum estimated burial temperatures for sediments below 915 m range from 80° to a a maximum of 150°C at 2400 m. The data suggests that the bulk of the sediment pile has not been exposed to temperatures above the oil window and possibly hydrocarbons have been generated deeper in the basin

Improving logistics costs for transportation and trade facilitation

Access to basic infrastructure services - roads, electricity, water, sanitation - and the efficient provision of the services, is a key challenge in the fight against poverty. Many of the poor (and particularly the extreme poor) in rural communities in Latin America live on average 5 kilometers or more from the nearest paved road, which is almost twice as far as non-poor rural households. There have been major improvements in access to water, sanitation, electricity, telecommunications, ports, and airports, but road coverage has not changed much, although some effort and resources have been invested to improve the quality of road networks. This paper focuses on the main determinants of logistics costs and physical access to services and, whenever possible, provides evidence of the effects of these determinants on competitiveness, growth, and poverty in Latin American economies. The analysis shows the impact of improving infrastructure and logistics costs on three fronts - macro (growth), micro (productivity at the firm level), and poverty (the earnings of poor/rural people). In addition, the paper provides recommendations and solutions that encompass a series of policies to reduce the prevalent high logistics costs and limited access to services in Latin America. The recommendations rely on applied economic analysis on logistics and trade facilitation.Transport Economics Policy&Planning,Economic Theory&Research,E-Business,Banks&Banking Reform,Transport and Trade Logistics

Aggregation and Insurance Mortality Estimation

One goal of government health insurance programs is to improve health, yet little is known empirically about how important such government interventions can be in explaining health transitions. We analyze the child mortality effects of a major health insurance expansion in Costa Rica. In contrast to previous work in this area that has used aggregated ecological designs, we exploit census data to estimate individual-level models. Theoretical and empirical econometric results indicate that aggregation can introduce substantial upward biases in the insurance effects. Overall we find a statistically significant but quite small effect of health insurance on child mortality in Costa Rica.

How to Leverage Strategic Alliances: The Success Factors of Strategic Alliance in Property Management

Companies pursue strategies to grow sales and increase market share by developing a more effective process, expanding into a new market, or obtaining an advantage over a competitor. This dissertation aims to understand the relationship between five success factors (i.e., partner commitment, partner trust and coordination, partner interdependence, partner capabilities, & partner information sharing) of a strategic alliance partnership agreement and strategic alliance performance and the role of partner cultural differences in this relationship. The overall goal of this dissertation is to understand how organizations can access the strengths, capabilities, knowledge, and trust that are paramount for strategic alliance in property management and to understand which success factors are deemed most valuable and important to those who work in the property management market segment that result in effective strategic alliance performance. An online survey was conducted using Mturk with about 523 participants vii from different organizations and sectors. Although the dissertation uses previously validated instruments, a Confirmatory Factor Analysis (CFA) using SPSS AMOS v.27 was performed to assess the factor structure of the data. The hypothesized direct relationships were tested using structural equation modeling (SEM) hierarchical regression analysis and simple slope moderation analysis using SPSS v.27. Results for the direct relationships revealed that partner commitment, partner trust and coordination, partner interdependence, partner capabilities, and partner information sharing was positively related to strategic alliance performance. Finally, the results revealed that the relationships between partner commitment and strategic alliance performance, partner trust and coordination and strategic alliance performance, partner interdependence and strategic alliance performance, partner capabilities and strategic alliance performance, and partner information sharing, and strategic alliance performance is higher when partner cultural difference is low rather than high. Implications of these findings are discussed. Keywords: Strategic Alliance Formations, Strategic Alliance Performance, Partner Capabilities, Partner Interdependence, Partner Trust and Coordination, Partner Commitment, Partner Information Sharing, and Partner Cultural Difference

Electrically controllable magnetism in twisted bilayer graphene

Twisted graphene bilayers develop highly localised states around AA-stacked regions for small twist angles. We show that interaction effects may induce either an antiferromagnetic (AF) and a ferromagnetic (F) polarization of said regions, depending on the electrical bias between layers. Remarkably, F-polarised AA regions under bias develop spiral magnetic ordering, with a relative $120^\circ$ misalignment between neighbouring regions due to a frustrated antiferromagnetic exchange. This remarkable spiral magnetism emerges naturally without the need of spin-orbit coupling, and competes with the more conventional lattice-antiferromagnetic instability, which interestingly develops at smaller bias under weaker interactions than in monolayer graphene, due to Fermi velocity suppression. This rich and electrically controllable magnetism could turn twisted bilayer graphene into an ideal system to study frustrated magnetism in two dimensions, with interesting potential also for a range of applications.Comment: 7 pages, 3 figures. Minor correction

Management of mydriasis and pain in cataract and intraocular lens surgery: review of current medications and future directions

The maintenance of mydriasis and the control of postoperative pain and inflammation are critical to the safety and success of cataract and intraocular lens replacement surgery. Appropriate mydriasis is usually achieved by topical and/or intracameral administration of anticholinergic agents, sympathomimetic agents, or both, with the most commonly used being cyclopentolate, tropicamide, and phenylephrine. Ocular inflammation is common after cataract surgery. Topical steroids and nonsteroidal anti-inflammatory drugs are widely used because they have been proved effective to control postsurgical inflammation and decrease pain. Topical nonsteroidal anti-inflammatory drugs have also been shown to help maintain dilation. However, use of multiple preoperative drops for pupil dilation, inflammation, and pain control have been shown to be time consuming, resulting in delays to the operating room, and they cause dissatisfaction among perioperative personnel; their use can also be associated with systemic side effects. Therefore, ophthalmologists have been in search of new options to streamline this process. This article will review the current medications commonly used for intraoperative mydriasis, as well as pain and inflammation control. In addition, a new combination of ketorolac, an anti-inflammatory agent, and phenylephrine, a mydriatic agent has recently been designed to maintain intraoperative mydriasis and to reduce postoperative pain and irritation from intraocular lens replacement surgery. Two Phase III clinical trials evaluating this combination have demonstrated statistically significant differences when compared to placebo in maintaining intraoperative mydriasis (P<0.00001) and in reducing pain in the early postoperative period (P=0.0002). This medication may be of benefit for use in cataract and lens replacement surgery in the near future