Model Closure and Price Formation Under Switching Grain Market Regimes in South Africa

This paper develops the structure and closure of an econometric regime-switching model within a partial equilibrium framework that has the ability to generate reliable estimates and projections of endogenous variables under market switching regimes. Models used in policy evaluation usually either ignore the possibility of regime switching using just a single method of price determination based on average effects, or incorporate highly stylised components that may not reflect the complexities of a particular market. This paper proposes an approach that the authors believe allows the incorporation of features of regime switching in a multisector commodity level model that capture salient features of the South African market and therefore are able to produce more reliable projections of the evolution of the sector under alternative shocks.Agricultural and Food Policy, Crop Production/Industries,

Challenges in Modeling the Effects of Trade Agreements on the Agricultural Sector

Major issues and challenges encountered in modeling and analyzing agricultural and trade policy reforms are reviewed. We focus on the modeling approach and pay special attention to the type and scope of the models, the calibration of a realistic baseline scenario, the representation of the reform agreement, the use of extra-model information, the choice of metrics to measure reform impacts, and emerging issues in policy modeling. Existing solutions and unresolved issues are examined. We stress the complementarity of various modeling approaches in assessing policy reforms and the importance of helping users understand the limitations of the chosen approach. Keywords: agricultural policy, economic modeling, trade agreements. JEL classification: Q17, Q18, F13

Model closure and price formation under switching grain market regimes in South Africa

This paper develops the structure and closure of an econometric regime-switching model within a partial equilibrium framework that has the ability to generate reliable estimates and projections of endogenous variables under market switching regimes. Models used in policy evaluation usually either ignore the possibility of regime switching using just a single method of price determination based on average effects, or incorporate highly stylised components that may not reflect the complexities of a particular market. This paper proposes an approach that the authors believe allows the incorporation of features of regime switching in a multisector commodity level model that capture salient features of the South African market and therefore are able to produce more reliable projections of the evolution of the sector under alternative shocks.Crop Production/Industries, Marketing,

I\u27ll Take It for What It Is Worth -- The Use of Hearsay Evidence by Labor Arbitrators: A Primer and Modest Proposal

This article considers these and other selected problems dealing with hearsay evidence that are likely to be encountered in the arbitral forum. It is our thesis that arbitrators do and should credit some (but not all) forms of hearsay evidence, but that the arbitral process is not served by admitting all evidence and taking it for what it is worth. Further, we believe when an advocate\u27s case against a grievant consists entirely of hearsay evidence, and there is no reliable substitute for cross examination or equivalent circumstantial guarantees of trustworthiness, the grievant should prevail. Only in the rarest of cases will management prevail when its evidence consists entirely of hearsay evidence

MTR and the EU Commission Proposal for the WTO: - An analysis of their effect on the EU and Irish agricultural sector

Further information may be found at http://www.tnet.teagasc.ie/fapri/pubandrep2003.htmIn the short history of the FAPRI-Ireland Partnership there has been no shortage of policy proposals to analyse. As part of the Agenda 2000 process the CAP is undergoing significant reform following the agreement made at the European Council in Berlin in 1999. This agreement had widespread implications for agriculture in Ireland, particularly for the beef sector. The changes that were agreed at that time have not even been fully implemented and there is already another reform document on the table, containing even more radical proposals for reform

A novel, non-invasive, online-monitoring, versatile and easy plant-based probe for measuring leaf water status

A high-precision pressure probe is described which allows non-invasive online-monitoring of the water relations of intact leaves. Real-time recording of the leaf water status occurred by data transfer to an Internet server. The leaf patch clamp pressure probe measures the attenuated pressure, Pp, of a leaf patch in response to a constant clamp pressure, Pclamp. Pp is sensed by a miniaturized silicone pressure sensor integrated into the device. The magnitude of Pp is dictated by the transfer function of the leaf, Tf, which is a function of leaf patch volume and ultimately of cell turgor pressure, Pc, as shown theoretically. The power function Tf=f(Pc) theoretically derived was experimentally confirmed by concomitant Pp and Pc measurements on intact leaflets of the liana Tetrastigma voinierianum under greenhouse conditions. Simultaneous Pp recordings on leaflets up to 10 m height above ground demonstrated that changes in Tf induced by Pc changes due to changes of microclimate and/or of the irrigation regime were sensitively reflected in corresponding changes of Pp. Analysis of the data show that transpirational water loss during the morning hours was associated with a transient rise in turgor pressure gradients within the leaflets. Subsequent recovery of turgescence during the afternoon was much faster than the preceding transpiration-induced water loss if the plants were well irrigated. Our data show the enormous potential of the leaf patch clamp pressure probe for leaf water studies including unravelling of the hydraulic communication between neighbouring leaves and over long distances within tall plants (trees)

Dose-finding study of a 90-day contraceptive vaginal ring releasing estradiol and segesterone acetate.

ObjectiveTo evaluate serum estradiol (E2) concentrations during use of 90-day contraceptive vaginal rings releasing E2 75, 100, or 200 mcg/day and segesterone acetate (SA) 200 mcg/day to identify a dose that avoids hypoestrogenism.Study designWe conducted a multicenter dose-finding study in healthy, reproductive-aged women with regular cycles with sequential enrollment to increasing E2 dose groups. We evaluated serum E2 concentrations twice weekly for the primary outcome of median E2 concentrations throughout initial 30-day use (target ≥40 pg/mL). In an optional 2-cycle extension substudy, we randomized participants to 2- or 4-day ring-free intervals per 30-day cycle to evaluate bleeding and spotting based on daily diary information.ResultsSixty-five participants enrolled in E2 75 (n = 22), 100 (n = 21), and 200 (n = 22) mcg/day groups; 35 participated in the substudy. Median serum E2 concentrations in 75 and 100 mcg/day groups were <40 pg/mL. In the 200 mcg/day group, median E2 concentrations peaked on days 4-5 of CVR use at 194 pg/mL (range 114-312 pg/mL) and remained >40 pg/mL throughout 30 days; E2 concentrations were 37 pg/mL (range 28-62 pg/mL) on days 88-90 (n = 11). Among the E2 200 mcg/day substudy participants, all had withdrawal bleeding following ring removal. The 2-day ring-free interval group reported zero median unscheduled bleeding and two (range 0-16) and three (range 0-19) unscheduled spotting days in extension cycles 1 and 2, respectively. The 4-day ring-free interval group reported zero median unscheduled bleeding or spotting days.ConclusionsEstradiol concentrations with rings releasing E2 200 mcg/day and SA 200 mcg/day avoid hypoestrogenism over 30-day use.ImplicationsA 90-day contraceptive vaginal ring releasing estradiol 200 mcg/day and segesterone acetate 200 mcg/day achieves estradiol concentrations that should avoid hypoestrogenism and effectively suppresses ovulation

FAPRI-Ireland 2003 EU Baseline Briefing Book

For six years the FAPRI-Ireland Partnership has been producing analysis of agricultural policy for the EU, with a focus on the impacts for Ireland. The process that generates this analysis involves first developing a baseline, a set of figures produced under the assumption that current policies remain in place. In the case of Europe, this means that agricultural policy in the EU is that which prevailed in January 2003. The baseline does include the reforms that were agreed under Agenda 2000 that have yet to be implemented for the dairy sector, where intervention prices were scheduled to fall between 2005 and 2007, and provisions from the Uruguay round

Probing Yukawa Unification with K and B Mixing

We consider corrections to the unification of down-quark and charged-lepton Yukawa couplings in supersymmetric GUTs, which links the large nu_tau-nu_mu mixing angle to b -> s transitions. These corrections generically occur in simple grand-unified models with small Higgs representations and affect s -> d and b -> d transitions via the mixing of the corresponding right-handed superpartners. On the basis of a specific SUSY-SO(10) model, we analyze the constraints from K-Kbar and B-Bbar mixing on the additional \tilde{d}_R-\tilde{s}_R rotation angle theta. We find that epsilon_K already sets a stringent bound on theta, theta^{max}=O(1 degree), indicating a very specific flavor structure of the correction operators. The impact of the large neutrino mixings on the unitarity triangle analysis is also briefly discussed, as well as their ability to account for the sizeable CP-violating phase observed recently in B_s -> psi phi decays.Comment: 19 pages. Discussion in Sec. 5.2 slightly extended; minor numerical modifications in Secs. 5.1 to 5.4, conclusions unchanged. Version to appear in JHE