Payments for Environmental Services under Emerging International Agreements: A Basis for Inclusion of Agricultural Soil Carbon Sinks.

This review places in context the role agricultural soils play in global carbon dynamics, and their potential interaction with climate change through soil carbon sequestration. The paper first examine the potential of soils as carbon sinks, agricultural practices and dynamics in soil organic carbon, emerging agreements on payments for environmental services (PES) that mitigate global warming through enhanced carbon sinks, exclusion of agricultural activities in PES under Kyoto Protocol, and the basis for inclusion of agricultural soil carbon sinks through sustainability based production systems. Soils are one of the planets largest sinks for carbon and hold potential for expanded carbon sequestration through changes in management. The global soil organic carbon (SOC) inventory is estimated to be 1200-1600 billion metric tonnes, which is equal to or slightly greater than amounts stored in terrestrial vegetation (500-700 billion metric tonnes) and the atmosphere (750 billion metric tonnes), combined. Agricultural soils, having been depleted of much of their native carbon stocks, and occupying an estimated 1.7 billion hectares, have a more significant potential SOC sink capacity. Global estimates of this sink capacity are in the order of 20-30 billion metric tonnes over the next 50-100 years. The total global agricultural soils SOC stocks are estimated at 167-170 billion metric tonnes. When soil is put into cultivation, associated biological and physical processes result in a release of SOC over time, often 50% or more, depending on soil conditions and agricultural practices. Consequently, there is potential to increase SOC in most cultivated soils. Many management practices have been demonstrated to increase SOC, including incorporation of crop residues, and increases in cropping intensity and fertilization. Past and on-going biophysical studies have been able to identify and demonstrate organic based soil fertility management practices, with modest applications of mineral fertilizers that would concurrently lead to improvement in SOC levels, nutrient loss amelioration and improved agricultural productivity. Management practices that could add 4 T C ha-1 yr-1 in the system have been demonstrated. Due to the potential impacts of climate change on the environment as a result of increasing concentration of GHGs in the atmosphere, particularly carbon dioxide, the world community established the Intergovernmental Panel on Climate Change (IPCC) in 1988. The responsibility of IPCC is to undertake an assessment of the science, impacts, adaptation, and mitigation options in relation to climate change and advise the Conference of Parties (COP) of the United Nations Framework Convention on Climate Change (UNFCCC). At the sixth Conference of the Parties (COP-6) in Marrakech, Morocco, limits were placed on the nature of activities that could be undertaken and the amount of carbon credits that could be generated through land use change and forestry activities to benefit from PES. These limits excluded all activities associated with management of natural forests and agricultural lands. This review argues that a demonstration of sustainability of carbon sinks in agricultural soils under empirically derived predictable management practices could serve as a basis for arguing the case for inclusion of carbon sinks in such systems in payments for environmental services under the Clean Development (CDM) of Kyoto Protocol.Environmental Economics and Policy,

Governance of Banking Institutions in Africa: Perceptions of Leading Players Within the Kenyan Banking Industry

Following an agency theoretic approach, this study sets out to investigate how banking institutions in Kenya are governed, using primarily semi-structured interview data. The study is incentivised by inadequate research on corporate governance of financial institutions within emerging economies. Accordingly, the study adopts an exploratory research design seeking to understand how governance is perceived and practiced within banks, together with the impact of corporate governance on performance of the Kenyan banking industry. The findings suggest that corporate governance is perceived differently within various banking institutions. It also emerges that corporate governance is practised along four broad lines within banks in Kenya: (a) board governance; (b) influences from global stage; (c) auditing; (d) shareholders. The results also reveal that corporate governance as considered by participants, boosts the performance of the Kenyan banking industry along three performance yardsticks: (a) going concern value; (b) cost-income ratio; (c) return on earnings. The results evidence some differences between the local institutional characteristics and assumptions founding the Anglo-American corporate governance model adopted in Kenya; where banks with concentrated ownership exhibit mainly principal-principal conflicts rather than principal-agent problems. The study recommends two mandatory independent audits - half-year and end-year audits, in order to enhance the corporate governance mechanism of disclosure, and improve governance and financial performance

Foreword

This Foreword provides an overview of Fifty Years of Loving v. Virginia and the Continued Pursuit of Racial Equality, a symposium hosted by the Fordham Law Review and cosponsored by the Fordham Law School Center on Race, Law & Justice. Even fifty years later, Loving provides ample foundation for an inquiry into the operation of race and racial inequality in the United States, which touches on the queries outlined above, as well as many others. In our view, a symposium focused on Loving makes a significant contribution by deepening scholarly analysis of that decision and by explicating the kinds of issues and concerns that should be at the heart of research concerning racial equality today

DC and Microwave Analysis of Gallium Arsenide Field-Effect Transistor-Based Nucleic Acid Biosensors

Sensitive high-frequency microwave devices hold great promise for biosensor design. These devices include GaAs field effect transistors (FETs), which can serve as transducers for biochemical reactions, providing a platform for label-free biosensing. In this study, a two-dimensional numerical model of a GaAs FET-based nucleic acid biosensor is proposed and simulated. The electronic band structure, space charge density, and current-voltage relationships of the biosensor device are calculated. The intrinsic small signal parameters for the device are derived from simulated DC characteristics and used to predict AC behavior at high frequencies. The biosensor model is based on GaAs field-effect device physics, semiconductor transport equations, and a DNA charge model. Immobilization of DNA molecules onto the GaAs sensor surface results in an increase in charge density at the gate region, resulting from negatively-charged DNA molecules. In modeling this charge effect on device electrical characteristics, we take into account the pre-existing surface charge, the orientation of DNA molecules on the sensor surface, and the distance of the negative molecular charges from the sensor surface. Hybridization with complementary molecules results in a further increase in charge density, which further impacts the electrical behavior of the device. This behavior is studied through simulation of the device current transport equations. In the simulations, numerical methods are used to calculate the band structure and self-consistent solutions for the coupled Schrodinger, Poisson, and current equations. The results suggest that immobilization and hybridization of DNA biomolecules at the biosensor device can lead to measurable changes in electronic band structure and current-voltage relationships. The high-frequency response of the biosensor device shows that GaAs FET devices can be fabricated as sensitive detectors of oligonucleotide binding, facilitating the development of inexpensive semiconductor-based molecular diagnostics suitable for rapid diagnosis of various disease states

Dose selection in seamless phase II/III clinical trials based on efficacy and toxicity

Seamless phase II/III clinical trials are attractive in development of new drugs because they accelerate the drug development process. Seamless phase II/III trials are carried out in two stages. After stage 1 (phase II stage), an interim analysis is performed and a decision is made on whether to proceed to stage 2 (phase III stage). If the decision is to continue with further testing, some dose selection procedure is used to determine the set of doses to be tested in stage 2. Methodology exists for the analysis of such trials that allows complete flexibility of the choice of doses that continue to the second stage. There is very little work, however, on optimizing the selection of the doses. This is a challenging problem as it requires incorporation of the dose-response relationship, of the observed safety profile and of the planned analysis method. In this thesis we propose a dose-selection procedure for binary outcomes in adaptive seamless phase II/III clinical trials that incorporates the dose response relationship, and explicitly incorporates both efficacy and toxicity. The choice of the doses to continue to stage 2 is made by comparing the predictive power of the potential sets of doses which might continue to stage 2

Uniformly minimum variance conditionally unbiased estimation in multi-arm multi-stage clinical trials

Multi-arm multi-stage clinical trials compare several experimental treatments with a control treatment, with poorly performing treatments dropped at interim analyses. This leads to inferential challenges, including the construction of unbiased treatment effect estimators. A number of estimators unbiased conditional on treatment selection have been proposed, but are specific to certain selection rules, may ignore the comparison to the control and are not all minimum variance. We obtain estimators for treatment effects compared to the control that are uniformly minimum variance unbiased conditional on selection with any specified rule or stopping for futility

Economic Evaluation of Organic and Inorganic Resources for Recapitalizing Soil Fertility in Smallholder Maize-based Cropping Systems of Central Kenya

Structural adjustments programs (SAPs) in the last two decades have eliminated all farm-support programs leading to low usage of fertilizers by Kenyan smallholders. One way of addressing this problem is use of organic nutrient resources. This paper examines their cost-effectiveness as capital investments in replenishment of Nitrogen (N), Phosphorus (P), Potassium (K) and soil organic matter (SOM) in smallholder, Maize-based cropping systems. On-farm trials were established in Maragwa and Kirinyaga Districts in 2003/04. Maize was planted in 3 replicates in randomised complete block design (RCBD) using different levels of organic and inorganic fertilizer resources. A blanket rate of 40kg P/ha was applied in all treatment except the control to increase organic N-utilization efficiency. The test crop was harvested, oven-dried and weighed. Net Present Values (NPV) were computed using Partial Budgeting Analysis Model. Increasing levels of inorganic N increased maize yields significantly (P<0.05). However, higher yields were necessary but not sufficient criteria to determine profitability of different treatments. Manure + 60 kg N/ha gave highest NPV (USD 564), Manure + 40kg N/ha gave second highest NPV (USD 511) in Maragwa District while Manure + 60kg N/ha gave highest NPV (USD 633) and Manure + 40kg N/ha second highest NPV (USD 618) in Kirinyaga District. These results suggested that higher N-levels were not necessarily the most economical. Use of organic resources with modest amounts of mineral fertilizers seemed more profitable and held the key to enhancement of nutrient budgets, food security and rural livelihoods.Natural resource capital, Net present values (NPV), Nutrient budgets, Smallholder farmers, Soil organic matter (SOM), Structural adjustment programs (SAPs), Crop Production/Industries, Land Economics/Use,

Estimation after subpopulation selection in adaptive seamless trials

During the development of new therapies, it is not uncommon to test whether a new treatment works better than the existing treatment for all patients who suffer from a condition (full population) or for a subset of the full population (subpopulation). One approach that may be used for this objective is to have two separate trials, where in the first trial, data are collected to determine if the new treatment benefits the full population or the subpopulation. The second trial is a confirmatory trial to test the new treatment in the population selected in the first trial. In this paper, we consider the more efficient two-stage adaptive seamless designs (ASDs), where in stage 1, data are collected to select the population to test in stage 2. In stage 2, additional data are collected to perform confirmatory analysis for the selected population. Unlike the approach that uses two separate trials, for ASDs, stage 1 data are also used in the confirmatory analysis. Although ASDs are efficient, using stage 1 data both for selection and confirmatory analysis introduces selection bias and consequently statistical challenges in making inference. We will focus on point estimation for such trials. In this paper, we describe the extent of bias for estimators that ignore multiple hypotheses and selecting the population that is most likely to give positive trial results based on observed stage 1 data. We then derive conditionally unbiased estimators and examine their mean squared errors for different scenarios

Clinico-surgical histopathological findings of retinoblastoma cases treated at Kenyatta National Hospital

Background: Retinoblastoma is a primitive embryonal anaplastic tumour composed of undifferentiated retinal elements. It is the most common primary, intraocular malignancy of childhood. After enucleation of the diseased eye, histopathological findings determine the secondary management of the patient. Histopathological spread of the disease is a major prognostic factor on survival of the patient.Objectives: To determine the surgical and histopathological findings of retinoblastoma cases treated at the Kenyatta National Hospital between 1st January 2000 and 31st December 2004 and to correlate gross appearance of globe after enucleation, with histopathological report.Design: Retrospective study.Setting: Kenyatta National Hospital, Kenya’s largest referral and teaching hospital.Subject: One hundred and sixty patients with clinically diagnosed and/or hystologicaly confirmed retinoblastoma.Results: The mean duration of symptoms was ten and a half five months (SD 10.7) median eight months. White reflex was most common symptom in 53.3% of cases, orbital swelling in 39.4%, pain and redness in 15%, squint in 5% and 21.9% had other complaints. On examination, leucocoria was found in 38.8% of patients, enucleated sockets 37%, recurrent mass in the socket in 27.5%, proptosis 22.5%, orbital swelling in 20% while only 1.3% of patients had strabismus. Tumour was found to be grossly confined to the eye ball in 23.0% of operated eyes, clinically outside the eye ball in 14.3% of eyes while 12.4% of operated eyes had thickened optic nerves. Histologically, tumour was confined to the eye ball in 30% of operated eyes while tumour involved the optic nerve but resection margin free of tumour in 3% of eyes. Tumour had extended beyond the resection margin of the optic nerve in 21% of cases. Eleven point four percent had choroidal extension and 24% were reported as having extrascleral spread. The sensitivity of the surgeon’s finding at surgery, when compared to the histological findings was found to be 69.4% while the specificity was 69.6%. The accuracy was 69.5%. Conclusion: There was still late presentation of retinoblastoma in our set up that had been found in studies conducted previously. This was confirmed by the histological findings. There was inadequate documentation of surgical findings, poor record management and a non-comprehensive referral system