3,077 research outputs found
SEARCHING FOR RATCHET EFFECTS IN AGRICULTURAL CONTRACTS
In a dynamic contracting environment, increasing standards over time in light of past performance is known as the ratchet effect. Despite the recent theoretical attention given to the ratchet effect, models that include these effects have not been empirically tested against contract data. In this study, we use farm-level data on modern Great Plains agricultural cash rent and cropshare contracts to test for the presence of ratchet effects in the context of a principal-agent model with moral hazard. We find limited evidence for the ratchet effect within share contracts, and no evidence that it is important for the choice of contract between cash rent and cropshare.Agribusiness,
Do Joint Parenting Laws Make Any Difference?
Using a unique data set on divorcing couples, we analyze the effects of a change in legal entitlement on the outcomes for divorcing couples. In particular, we analyze the 1997 change to custody provisions in the State of Oregon. Prior to 1997, Oregon assigned custody, based on the discretion of the court, in the best interests of the child. This was changed to a presumption- of joint parenting, which manifests in the courts encouraging and imposing joint (or shared) custody in cases that otherwise would have had sole custody arrangements. We find that the law had several implications for divorce behavior: different custody outcomes (less sole custody to mothers, more sole custody to fathers), more mediation, longer times until the final divorce, and more acrimonious divorces (more abuse actions filed). We find no evidence that spouses attempted to bargain around the change of legal entitlement
Child Support Guidelines and Divorce Incentives
A child support guideline is a formula used to calculate support payments based on a few family characteristics. Guidelines began replacing court awarded support payments in the late 1970s and early 1980s, and were eventually mandated by the federal government in 1988. Two fundamentally different types of guidelines are used: percentage of obligor income, and income shares models. This paper explores the incentives to divorce under the two schemes, and uses the NLSY data set to test the key predictions. We find that percentage of obligor income models are destabilizing for some families with high incomes. This may explain why several states have converted from obligor to income share models, and it provides a subtle lesson for the no-fault divorce debate
Lunar material transport vehicle
The proposed vehicle, the Lunar Material Transport Vehicle (LMTV), has a mission objective of efficient lunar soil material transport. The LMTV was designed to meet a required set of performance specifications while operating under a given set of constraints. The LMTV is essentially an articulated steering, double-ended dump truck. The vehicle moves on four wheels and has two identical chassis halves. Each half consists of a chassis frame, a material bucket, two wheels with integral curvilinear synchronous motors, a fuel cell and battery arrangement, an electromechanically actuated dumping mechanism, and a powerful microprocessor. The vehicle, as designed, is capable of transporting up to 200 cu ft of material over a one mile round trip per hour. The LMTV is capable of being operated from a variety of sources. The vehicle has been designed as simply as possible with attention also given to secondary usage of components
Methodological issues in assessing changes in costs pre- and post-medication switch: a schizophrenia study example
<p>Abstract</p> <p>Background</p> <p>Schizophrenia is a severe, chronic, and costly illness that adversely impacts patients' lives and health care payer budgets. Cost comparisons of treatment regimens are, therefore, important to health care payers and researchers. Pre-Post analyses ("mirror-image"), where outcomes prior to a medication switch are compared to outcomes post-switch, are commonly used in such research. However, medication changes often occur during a costly crisis event. Patients may relapse, be hospitalized, have a medication change, and then spend a period of time with intense use of costly resources (post-medication switch). While many advantages and disadvantages of Pre-Post methodology have been discussed, issues regarding the attributability of costs incurred around the time of medication switching have not been fully investigated.</p> <p>Methods</p> <p>Medical resource use data, including medications and acute-care services (hospitalizations, partial hospitalizations, emergency department) were collected for patients with schizophrenia who switched antipsychotics (n = 105) during a 1-year randomized, naturalistic, antipsychotic cost-effectiveness schizophrenia trial. Within-patient changes in total costs per day were computed during the pre- and post-medication change periods. In addition to the standard Pre-Post analysis comparing costs pre- and post-medication change, we investigated the sensitivity of results to varying assumptions regarding the attributability of acute care service costs occurring just after a medication switch that were likely due to initial medication failure.</p> <p>Results</p> <p>Fifty-six percent of all costs incurred during the first week on the newly initiated antipsychotic were likely due to treatment failure with the previous antipsychotic. Standard analyses suggested an average increase in cost-per-day for each patient of 4.77 to $9.69 per day post-switch.</p> <p>Conclusion</p> <p>Pre-Post cost analyses are sensitive to the approach used to handle acute-service costs occurring just after a medication change. Given the importance of quality economic research on the cost of switching treatments, thorough sensitivity analyses should be performed to identify the impact of crisis events around the time of medication change.</p
Analysis and Prediction of Telephone Demand in Local Geographic Areas
An approach to forecasting the demand or local area telephone service is presented in this paper. The specific problem discussed is the fore casting of main stations in three Michigan metropolitan areas. Several different statistical models are used. The first class of models introduced uses adaptive exponential smoothing and is based solely on the past history of the time series involved. Although appropriate data at the local area level are very difficult to obtain, two exogenous time series related to household formations are used to construct more elaborate models for one of the areas. The various models are evaluated by both the average absolute and the root-mean-square forecast error. In terms of these criteria, the first class of models referred to above performs reasonably well while the second set does considerably better. This argues strongly that future improvements in forecasting accuracy will be made by the more extensive involvement of exogenous variables
Classification of a Haemophilus influenzae ABC Transporter HI1470/71 through Its Cognate Molybdate Periplasmic Binding Protein, MoIA
molA (HI1472) from H. influenzae encodes a periplasmic binding protein (PBP) that delivers substrate to the ABC transporter MolB_2C_2 (formerly HI1470/71). The structures of MolA with molybdate and tungstate in the binding pocket were solved to 1.6 and 1.7 Å resolution, respectively. The MolA-binding protein binds molybdate and tungstate, but not other oxyanions such as sulfate and phosphate, making it the first class III molybdate-binding protein structurally solved. The ~100 μM binding affinity for tungstate and molybdate is significantly lower than observed for the class II ModA molybdate-binding proteins that have nanomolar to low micromolar affinity for molybdate. The presence of two molybdate loci in H. influenzae suggests multiple transport systems for one substrate, with molABC constituting a low-affinity molybdate locus
Cosmology and Astrophysics from Relaxed Galaxy Clusters II: Cosmological Constraints
We present cosmological constraints from measurements of the gas mass
fraction, , for massive, dynamically relaxed galaxy clusters. Our data
set consists of Chandra observations of 40 such clusters, identified in a
comprehensive search of the Chandra archive, as well as high-quality weak
gravitational lensing data for a subset of these clusters. Incorporating a
robust gravitational lensing calibration of the X-ray mass estimates, and
restricting our measurements to the most self-similar and accurately measured
regions of clusters, significantly reduces systematic uncertainties compared to
previous work. Our data for the first time constrain the intrinsic scatter in
, % in a spherical shell at radii 0.8-1.2 ,
consistent with the expected variation in gas depletion and non-thermal
pressure for relaxed clusters. From the lowest-redshift data in our sample we
obtain a constraint on a combination of the Hubble parameter and cosmic baryon
fraction, , that is insensitive to the
nature of dark energy. Combined with standard priors on and ,
this provides a tight constraint on the cosmic matter density,
, which is similarly insensitive to dark energy. Using
the entire cluster sample, extending to , we obtain consistent results for
and interesting constraints on dark energy:
for non-flat CDM models, and
for flat constant- models. Our results are both competitive
and consistent with those from recent CMB, SNIa and BAO data. We present
constraints on models of evolving dark energy from the combination of
data with these external data sets, and comment on the possibilities for
improved constraints using current and next-generation X-ray
observatories and lensing data. (Abridged)Comment: 25 pages, 14 figures, 8 tables. Accepted by MNRAS. Code and data can
be downloaded from http://www.slac.stanford.edu/~amantz/work/fgas14/ . v2:
minor fix to table 1, updated bibliograph
Active synthetic soil
A synthetic soil/fertilizer for horticultural application having all the agronutrients essential for plant growth is disclosed. The soil comprises a synthetic apatite fertilizer having sulfur, magnesium, and micronutrients dispersed in a calcium phosphate matrix, a zeolite cation exchange medium saturated with a charge of potassium and nitrogen cations, and an optional pH buffer. Moisture dissolves the apatite and mobilizes the nutrient elements from the apatite matrix and the zeolite charge sites
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