CONTRACT INCENTIVES AND EXCESSIVE NITROGEN USE IN AGRICULTURE

This study examines incentives for input use under tournament contracts. We analyze implications of contract design for nitrate-based environmental externalities generated by agricultural producers. Outcomes are compared from contracts awarded by tournament to those from fixed-payment contracts. Our findings show contract insecurity can distort input use. The model developed in this analysis is applied to a region of the U.S. where tournament-based production is prevalent and groundwater contamination is a problem. We find contract insecurity increases nitrogen use by about 12%, resulting in a 17% increase in nitrate leaching. Implications for contract modification to reduce environmental externalities while maintaining contract incentives are discussed.Crop Production/Industries,

Epidemic dynamics of respiratory syncytial virus in current and future climates.

A key question for infectious disease dynamics is the impact of the climate on future burden. Here, we evaluate the climate drivers of respiratory syncytial virus (RSV), an important determinant of disease in young children. We combine a dataset of county-level observations from the US with state-level observations from Mexico, spanning much of the global range of climatological conditions. Using a combination of nonlinear epidemic models with statistical techniques, we find consistent patterns of climate drivers at a continental scale explaining latitudinal differences in the dynamics and timing of local epidemics. Strikingly, estimated effects of precipitation and humidity on transmission mirror prior results for influenza. We couple our model with projections for future climate, to show that temperature-driven increases to humidity may lead to a northward shift in the dynamic patterns observed and that the likelihood of severe outbreaks of RSV hinges on projections for extreme rainfall

Welfare Risks of Repeated Application of On-Farm Killing Methods for Poultry

Council Regulation (EC) no. 1099/2009 on the protection of animals at the time of killing restricts the use of manual cervical dislocation in poultry on farms in the European Union (EU) to birds weighing up to 3 kg and 70 birds per person per day. However, few studies have examined whether repeated application of manual cervical dislocation has welfare implications and whether these are dependent on individual operator skill or susceptibility to fatigue. We investigated the effects of repeated application (100 birds at a fixed killing rate of 1 bird per 2 min) and multiple operators on two methods of killing of broilers, laying hens, and turkeys in commercial settings. We compared the efficacy and welfare impact of repeated application of cervical dislocation and a percussive killer (Cash Poultry Killer, CPK), using 12 male stockworkers on three farms (one farm per bird type). Both methods achieved over 96% kill success at the first attempt. The killing methods were equally effective for each bird type and there was no evidence of reduced performance with time and/or bird number. Both methods of killing caused a rapid loss of reflexes, indicating loss of brain function. There was more variation in reflex durations and post-mortem damage in birds killed by cervical dislocation than that found using CPK. High neck dislocation was associated with improved kill success and more rapid loss of reflexes. The CPK caused damage to multiple brain areas with little variation. Overall, the CPK was associated with faster abolition of reflexes, with fewer birds exhibiting them at all, suggestive of better welfare outcomes. However, technical difficulties with the CPK highlighted the advantages of cervical dislocation, which can be performed immediately with no equipment. At the killing rates tested, we did not find evidence to justify the current EU limit on the number of birds that one operator can kill on–farm by manual cervical dislocation

Thermophysical properties of Co-free WC-FeCr hardmetals

Fe-Cr alloys can potentially replace carcinogenic Co as the binder system in WC-hardmetals. Furthermore, they may be used in emerging applications such as nuclear fusion reactor shielding, where use of Co is forbidden due to the formation of hazardous activated species. In such applications, a good understanding of thermophysical properties is critical to predicting high temperature performance. By combining several thermal analysis techniques (dilatometry, laser flash and calorimetry) we have determined the thermal conductivity and thermal expansivity of several grades of WC-FeCr hardmetals between room temperature and 1200 °C. In these materials the WC grain size was varied between 0.2 and 5 microns. The binder content was kept constant at 10 wt.%, and the nominal binder composition was Fe-8 wt.% Cr. The room temperature thermal conductivities of these materials varied between about 50 and 110 W/m-K, which are similar values to analogous WC-Co materials. Thermal expansion curves exhibited discontinuous shrinkage events at about 850 °C, due to an allotropic phase transition within the FeCr binder between its BCC and FCC structures. The magnitude of the shrinkage was about a third that predicted by the rule-of-mixtures, suggesting significant internal stresses could be generated during the transformation. Such internal stresses could affect the properties of WC-FeCr hardmetals when operating at high temperature

Predictors of Achievement When Virtual Manipulatives are Used for Mathematics Instruction

The purpose of this study was to determine variables that predict performance when virtual manipulatives are used for mathematics instruction. This study included the following quasi-experimental design features: 1) a large number of students (N=350); 2) within-class random-assignment to treatment groups; 3) retention effects measured by post-test and delayed post-test; 4) fidelity of instructional treatments documented through observations; and, 5) instrument development for the unit of study. This design was used to determine variables that predict student performance on tests of fraction knowledge for third- and fourth-grade students in two treatment groups: classroom instruction using texts and physical manipulatives (CI), and computer lab instruction using virtual fraction applets (VM). The Pre-test, Post-test 1, and Post-test 2 measured learning and retention of fraction concepts. Observation ethograms documented representation use. The results revealed that fewer demographic predictors of student performance (e.g., socio-economic status, English language learner status, and gender) exist during fraction instruction when virtual manipulatives were used. When instructors used virtual manipulatives, there was an equalizing effect on achievement in third and fourth grade classrooms, in that fewer demographic factors were influential for VM groups compared to CI groups

Epilepsy, cognitive deficits and neuroanatomy in males with ZDHHC9 mutations.

OBJECTIVE: Systematic investigation of individuals with intellectual disability after genetic diagnosis can illuminate specific phenotypes and mechanisms relevant to common neurodevelopmental disorders. We report the neurological, cognitive and neuroanatomical characteristics of nine males from three families with loss-of-function mutations in ZDHHC9 (OMIM #300799). METHODS: All known cases of X-linked intellectual disability (XLID) due to ZDHHC9 mutation in the United Kingdom were invited to participate in a study of neurocognitive and neuroimaging phenotypes. RESULTS: Seven out of nine males with ZDHHC9 mutations had been diagnosed with epilepsy, exceeding epilepsy risk in XLID comparison subjects (P = 0.01). Seizure histories and EEG features amongst ZDHHC9 mutation cases shared characteristics with rolandic epilepsy (RE). Specific cognitive deficits differentiated males with ZDHHC9 mutations from XLID comparison subjects and converged with reported linguistic and nonlinguistic deficits in idiopathic RE: impaired oromotor control, reduced verbal fluency, and impaired inhibitory control on visual attention tasks. Consistent neuroanatomical abnormalities included thalamic and striatal volume reductions and hypoplasia of the corpus callosum. INTERPRETATION: Mutations in ZDHHC9 are associated with susceptibility to focal seizures and specific cognitive impairments intersecting with the RE spectrum. Neurocognitive deficits are accompanied by consistent abnormalities of subcortical structures and inter-hemispheric connectivity. The biochemical, cellular and network-level mechanisms responsible for the ZDHHC9-associated neurocognitive phenotype may be relevant to cognitive outcomes in RE.This study was funded by the Wellcome Trust/Academy of Medical Sciences (Starter Grant for Clinical Lecturers to K. B.). K. B. is funded by the National Institute of Health Research (Academic Clinical Lectureship). J. B. and D. A. are funded by an MRC UK intramural programme (MCA0606- 5PQ41). G. S. is funded by Wellcome Trust project grant (WT079326AIA) and a James S. McDonnell Foundation Understanding Human Cognition Scholar Award. F. L. R. is funded by the National Institute of Health Research (Cambridge Biomedical Research Centre).This is the final published version. It first appeared at http://onlinelibrary.wiley.com/doi/10.1002/acn3.196/full

On Farm Evaluation of a Novel Mechanical Cervical Dislocation Device for Poultry

Urgent development of alternative on-farm killing methods for poultry is required following the number restrictions placed on the use of traditional manual cervical dislocation by European Legislation (EU 1099/2009). Alternatives must be proven to be humane and, crucially, practical in commercial settings with multiple users. We assessed the performance and reliability of a novel mechanical cervical dislocation device (NMCD) compared to the traditional manual cervical dislocation (MCD) method. NMCD was based on a novel device consisting of a thin supportive glove and two moveable metal finger inserts designed to aid the twisting motion of cervical dislocation. We employed a 2 × 2 factorial design, with a total of eight stockworkers from broiler and layer units (four per farm) each killing 70 birds per method. A successful kill performance was defined as immediate absence of rhythmic breathing and nictitating membrane reflex; a detectable gap in the vertebrae and only one kill attempt (i.e., one stretch and twist motion). The mean stockworker kill performance was significantly higher for MCD (98.4 ± 0.5%) compared to NMCD (81.6 ± 1.8%). However, the MCD technique normally used by the stockworkers (based previous in-house training received) affected the performance of NMCD and was confounded by unit type (broilers), with the majority of broiler stockworkers trained in a non-standard technique, making adaption to the NMCD more difficult. The consistency of trauma induced by the killing methods (based on several post-mortem parameters) was higher with NMCD demonstrated by “gold standard” trauma achieved in 30.2% of birds, compared to 11.4% for MCD (e.g., dislocation higher up the cervical region of the spine i.e., between vertebrae C0–C1, ≥1 carotid arteries severed), suggesting it has the potential to improve welfare at killing. However, the results also suggest that the NMCD method requires further refinement and training optimization in order for it to be acceptable as an alternative across poultry industry, irrespective of previous MCD technique and training

A Race against Time: Reduced Azithromycin Susceptibility in Salmonella enterica Serovar Typhi in Pakistan

Antimicrobial resistance is an ongoing issue in the treatment of typhoid fever. Resistance to first-line antimicrobials and extensively drug resistant (XDR) Salmonella Typhi isolates in Pakistan have left azithromycin as the only remaining effective oral treatment. Here, we report the emergence of organisms with a single point mutation in acrB gene, implicated in azithromycin resistance, in a S. Typhi isolate from Pakistan. The isolation of this organism is worrisome and highlights the significance of the introduction of typhoid conjugate vaccine in South Asia.Importance: The emergence of XDR Salmonella Typhi in Pakistan has left azithromycin as the only viable oral treatment option. Here, we report the detection of an azithromycin resistance-associated mutation in one S. Typhi isolate. This finding is important because any possible spread of azithromycin resistance in S. Typhi isolates would make it nearly impossible to treat in outpatient settings due to the need of injectable antibiotics. Our findings also signify the importance of introduction of typhoid conjugate vaccine in regions of endemicity such as Pakistan

Dynamic fibronectin assembly and remodeling by leader neural crest cells prevents jamming in collective cell migration

Collective cell migration plays an essential role in vertebrate development, yet the extent to which dynamically changing microenvironments influence this phenomenon remains unclear. Observations of the distribution of the extracellular matrix (ECM) component fibronectin during the migration of loosely connected neural crest cells (NCCs) lead us to hypothesize that NCC remodeling of an initially punctate ECM creates a scaffold for trailing cells, enabling them to form robust and coherent stream patterns. We evaluate this idea in a theoretical setting by developing an agent-based model that incorporates reciprocal interactions between NCCs and their ECM. ECM remodeling, haptotaxis, contact guidance, and cell-cell repulsion are sufficient for cells to establish streams in silico, however additional mechanisms, such as chemotaxis, are required to consistently guide cells along the correct target corridor. Further investigations of the model imply that contact guidance and differential cell-cell repulsion between leader and follower cells are key contributors to robust collective cell migration by preventing stream breakage. Global sensitivity analysis and simulated underexpression/overexpression experiments suggest that long-distance migration without jamming is most likely to occur when leading cells specialize in creating ECM fibers, and trailing cells specialize in responding to environmental cues by upregulating mechanisms such as contact guidance.Comment: 46 pages, 7 figures (of which 2 are supplementary