Effects of Fertilizer and Shade Management on Nitrogen Mineralization, Nitrifying Microbial Abundance and Nitrogen-Fixing Capacity of Erythrina poeppigiana in Coffee (Coffea arabica) Agroforestry Systems in Costa Rica

Worldwide chemical fertilizer use has increased by four times during the last 50 years. Conventional agricultural systems have a high nitrifying nature, resulting in a loss of nearly 70% of overall nitrogen (N) fertilizer inputs, an estimated economic loss of $81 billion. Over application of fertilizer is rampant in tropical developing nations in Central America, where coffee is major crop. Agroforestry offers ecologically sustainable land management strategies that promote the provision of ecosystem services such as, protection of biodiversity, climate change mitigation, and water and soil regulation. When legume trees are incorporated as the shade tree in coffee production, direct inputs of nitrogen can occur. The specific objectives of this study were, (1) to quantify the effects of inorganic fertilizer and shade treatments on soil organic carbon (SOC), (2) measure and quantify the mineralization rates under inorganic fertilizer and shade treatments, (3) determine if the spatial abundance of ammonia oxidizing bacteria (AOB) is affected by varying shade management, or by inorganic fertilizer treatment, and 4) measure the effects of inorganic fertilizer application on the transfer of biologically fixed N by Erythrina poeppigiana to Coffea arabica in agroforestry systems in the region. The field study was conducted in Aquiares, Costa Rica. Chemical fertilizer was applied between four treatments at the rate of 0, 110, 170, and 230 kg N ha-1 yr-1 and coupled with three shade treatments (no shade, managed shade, full shade) defined by the management strategies of the legume tree E. poeppigiana. Analyses showed no significant difference in total SOC by fertilizer and shade treatments. Measured NH4+ µmol/L NH4+ and NO2- + NO3- µmol/L NO3- concentrations differed significantly by the shade treatment, but net nitrogen mineralization rates were not significantly different by fertilizer or shade treatment. A significant difference in dsDNA copy number of AOB per soil g-1 was determined by shade treatment. Finally, fertilizer treatment demonstrated a significant effect on the potential for biologically fixed nitrogen from E. poeppigiana to be transferred to coffee planted in association. Coffee agroforestry systems with full shade E. poeppigiana legume trees offered additional inputs of nitrogen to mitigate the use of chemical fertilizers

Congress and Early Federalist Military Policy: An Examination of Defense Related Roll Calls in the Second United States Congress, 1792-1793

The legislators of the Second United States House of Representatives faced a set of challenging military and political problems when they met in November 1791. The issue of what would be the primary means of the young nation\u27s defense had not yet been determined. The old British and colonial precedents of a militia as the first line of defense were firmly rooted in the minds of most congressmen meeting in Philadelphia. Many of the legislators had been indelibly imprinted with a fear of a large standing army in peacetime from their own personal experiences in the pre-Revolutionary days. Many of those who would become stalwarts of the Republican Party in later years felt that a militia, while often miltarily ineffective, preserved the republican virtues on which the nation depended for its moral underpinnings. Others, who were usually in the ranks of the future Federalist party, felt that a well-trained regular federal force was the only practical military solution for the nation\u27s long-term needs, barring vast improvements in the training and discipline of the state militia forces. Underlying both considerations by the members of the Second Congress was the pressing need for a military solution of some sort in the Northwest Territory. With a series of military embarrassments suffered at the hands of the frontier Indian tribes, the issue of how best to achieve military respectability took its place alongside other important matters in the Second Congress. Occurring also at this time was the emergence of factions that would later evolve into two distinct and antagonistic political parties. Aside from the standard methods of research, such as examining the debates of Congress and studying newspapers and documents of the time, I used the Rice-Beyle cluster bloc analysis technique to discover the existence of congressional voting patterns. This method examines the voting behavior of paired congressmen to determine similar voting behavior. I separated the roll calls dealing with the issues of a stronger, reorganized militia from those pertaining to a more potent regular army for use on the frontier and anlyzed both sets of data for voting patterns. I also examined the voting patterns for all 102 roll calls of this Congress. In the end, I discovered that smaller groups of legislators than I expected voted together consistently on military issues, while voting in opposing factions on the overall business of the House

How Well Do We Know the Beta-Decay of 16N and Oxygen Formation in Helium Burning

We review the status of the 12C(a,g)16O reaction rate, of importance for stellar processes in a progenitor star prior to a super-nova collapse. Several attempts to constrain the p-wave S-factor of the 12C(a,g)16O reaction at Helium burning temperatures (200 MK) using the beta-delayed alpha-particle emission of 16N have been made, and it is claimed that this S-factor is known, as quoted by the TRIUMF collaboration. In contrast reanalyses (by G.M. hale) of all thus far available data (including the 16N data) does not rule out a small S-factor solution. Furthermore, we improved our previous Yale-UConn study of the beta- delayed alpha-particle emission of \n16 by improving our statistical sample (by more than a factor of 5), improving the energy resolution of the experiment (by 20%), and in understanding our line shape, deduced from measured quantities. Our newly measured spectrum of the beta-delayed alpha-particle emission of 16N is not consistent with the TRIUMF('94) data, but is consistent with the Seattle('95) data, as well as the earlier (unaltered !) data of Mainz('71). The implication of this discrepancies for the extracted astrophysical p-wave s-factor is briefly discussed.Comment: 6 pages, 4 figures, Invited Talk, Physics With Radioactive Beams, Puri, India, Jan. 12-17, 1998, Work Supported by USDOE Grant No. DE-FG02-94ER4087

Test and model correlation of the atmospheric emission photometric imager fiberglass pedestal

The correlation is presented of the static loads testing and finite element modeling for the fiberglass pedestal used on the Atmospheric Emission Photometric Imaging (AEPI) experiment. This payload is to be launched in the space shuttle as part of the ATLAS-1 experiment. Strain gauge data from rosettes around the highly loaded base are compared to the same load case run for the Spacelab 1 testing done in 1981. Correlation of the model and test data was accomplished through comparison of the composite stress invariant using the expected flight loads for the ATLAS-1 mission. Where appropriate, the Tsai-Wu failure criteria was used in the development of the key margins of safety. Margins of safety are all positive for the pedestal and are reported

Managerial Discretion: An Empirical Review and Focus on Future Research Directions

Scholars have long been interested in when and to what degree managers are able to exert control over their organizations. In this review, we examine managerial discretion, or the latitude of action available to managers. Since its introduction, scholars have attempted to explain when managers will have discretion, what discretion means for organizational outcomes, and how discretion may differentially influence organizational outcomes when it enables or constrains leaders. Our review indicates that while a significant number of studies have examined discretion, few have attempted to validate the prescriptions of the managerial discretion construct. Furthermore, studies to date have primarily focused on the industry task environment as a measure of discretion, with less attention focused on the manager’s characteristics and the internal organization. We then assess construct validity and the measurement of managerial discretion, offering recommendations to future researchers for improving the operationalization of this construct. Finally, we consider how discretion forces may interact as either complements or substitutes and how such interactions may have both organizational- and individual-level consequences

Board Committees in Corporate Governance: A Cross-Disciplinary Review and Agenda for the Future

The importance of board committees – specialized subgroups that exist to perform many of the board\u27s most critical functions, such as setting executive compensation, identifying potential board members, and overseeing financial reporting – has grown over time due to increased legal requirements and greater complexity of the environment in which firms operate. This has resulted in a large body of work examining board committees across the accounting, finance, and management disciplines. However, this research has developed rather independently within each discipline, preventing scholars and practitioners from developing a comprehensive understanding of board committees. To address this issue, we conduct a comprehensive review of the literature that: 1) summarizes and synthesizes antecedents and outcomes associated with board committees in publicly-traded firms in English common law countries; and 2) offers a critical analysis of existing research, providing recommendations for advancements and new directions in board committee research

Board Committees in Corporate Governance: A Cross‐Disciplinary Review and Agenda for the Future

The importance of board committees – specialized subgroups that exist to perform many of the board\u27s most critical functions, such as setting executive compensation, identifying potential board members, and overseeing financial reporting – has grown over time due to increased legal requirements and greater complexity of the environment in which firms operate. This has resulted in a large body of work examining board committees across the accounting, finance, and management disciplines. However, this research has developed rather independently within each discipline, preventing scholars and practitioners from developing a comprehensive understanding of board committees. To address this issue, we conduct a comprehensive review of the literature that: 1) summarizes and synthesizes antecedents and outcomes associated with board committees in publicly‐traded firms in English common law countries; and 2) offers a critical analysis of existing research, providing recommendations for advancements and new directions in board committee research

Collision Avoidance for Airport Traffic Concept Evaluation

An initial Collision Avoidance for Airport Traffic (CAAT) concept for the Terminal Maneuvering Area (TMA) was evaluated in a simulation study at the National Aeronautics and Space Administration (NASA) Langley Research Center. CAAT is being designed to enhance surface situation awareness and provide cockpit alerts of potential conflicts during runway, taxi, and low altitude air-to-air operations. The purpose of the study was to evaluate the initial concept for an aircraft-based method of conflict detection and resolution (CD&R) in the TMA focusing on conflict detection algorithms and alerting display concepts. This paper gives an overview of the CD&R concept, simulation study, and test results

Collision Avoidance for Airport Traffic Simulation Evaluation

A Collision Avoidance for Airport Traffic (CAAT) concept for the airport Terminal Maneuvering Area (TMA) was evaluated in a simulation study at the National Aeronautics and Space Administration (NASA) Langley Research Center. CAAT is being designed to enhance surface situation awareness and provide cockpit alerts of potential conflicts during runway, taxi, and low altitude air-to-air operations. The purpose of the study was to evaluate pilot reaction to conflict events in the TMA near the airport, different alert timings for various scenarios, alerting display concepts, and directive alerting concepts. This paper gives an overview of the conflict detection and resolution (CD&R) concept, simulation study, and test result