Impact Of Changes In Management Research Articles

A regional audit of nitrogen fluxes in pampean agroecosystems

Calculations of nitrogen (N) budgets can help in the understanding of agroecosystem functioning and in proposing more sustainable management strategies. Changes in the main N fluxes of the pampean agroecosystems of Argentina were calculated over time. The impact of management changes on regional N budget and possible future trends were estimated. Changes in land use were quantified using national censuses data. Biological N fixation of leguminous forages was assessed using a regression model and local field experimental data. Nitrogen fixation by soybean, the most extensive grain crop, was calculated using an existing model. Fertilizer input was based upon farmer surveys, and atmospheric N input estimated using local data. Nitrogen output by grain harvest was estimated using national yield statistics and averaged grain N concentration derived from many field experiments widespread over the region. During the last 50 years cropped area has doubled as a result of the widespread adoption of soybean as the main component of rotations. The agricultural expansion included areas previously used for grazing on seeded pastures and seasonal graminaceus forages. The historical N budget of the entire region was positive but has dropped from 2.0Mty−1 in 1960 to 1.3Mty−1 at present. This reduction implies that N fixation by soybean and fertilizer application were lower than the previous livestock/pasture systems N input. During the cropping phase of rotations the N budget was usually negative in the past. Currently, in low yielding areas of semiarid environments, the N budget turned positive; meanwhile in humid climates with high productivity scenarios it remained negative. Fertilizer rates applied balanced N output in the former case but not in the latter. Partial factor productivity of N inputs increased from 3- to 6-fold during the last 50 years in the Pampas. Uncertainties related to the estimations performed are discussed.

Mean reversion or a breath of fresh air? The effect of NFL coaching changes on team performance in the salary cap era

Just as firms must consider the impact of changes in management, sports teams must consider whether a coaching change will improve the team’s on-field performance. I examine the effects of coaching changes for National Football League (NFL) teams between the 1995 and 2012 seasons. A variety of factors contribute to an NFL team’s performance reverting towards league-average levels between seasons. Thus, a nominal improvement in team performance could be due to improved management or it could simply be mean reversion. I find that, after accounting for the highly significant mean reversion effect during this time period, firing a coach reduces a team’s expected performance during the next season and the team’s average performance over the next two seasons. This effect is present when wins are used to measure performance, but also when performance is measured by point differential and playoff appearances, two variables that avoid some shortcomings of using team wins as a measure of performance. I conclude that teams are firing coaches an inefficiently high percentage of the time.

The humus balance model (HU-MOD): a simple tool for the assessment of management change impact on soil organic matter levels in arable soils

With this paper we present a simple model for the assessment of management impact in arable farming systems on soil organic matter (SOM) levels. The humus balance model (HU-MOD) is designed for application by farmers and extension workers in practice as a tool for management support. To enable practice applicability, HU-MOD bypasses the need for data on soil parameters and can be run with simple management data. HU-MOD is based on a simplified model on carbon and nitrogen pools and fluxes in the soil–plant system. The model proved to be an applicable simple tool for the comparison of management systems in arable farming with regard to the impact on SOM levels. Even though an absolute quantification of SOM level changes is not possible due to the methodical approach bypassing the need for any data on soil parameters, the model may be used to assess a positive or negative impact of a management system or management period compared to a reference and thus may be used to assess the impact of management changes, or to analyse a specific impact for different management periods on a defined spatial unit.

Using fine‐scale catch predictions to examine spatial variation in growth and catchability of Panulirus cygnus along the west coast of Australia

Puerulus settlement has been monitored throughout the western rock lobster Panulirus cygnus fishery for nearly 40 years. These data, in combination with indices of effort and water temperature, were used to produce recruitment‐catch relationships for each 1° transect of latitude in the coastal part of this fishery from Kalbarri to Cape Leeuwin, as well as at the offshore Abrolhos Islands (total of eight transects). The fine spatial scales of these models provided estimates of certain life history traits that are known to affect lobster catches between adjacent fishing ports. This catch modelling showed that the proportions of 3‐ and 4‐year‐old post‐settlement lobsters contributing to the catches varied markedly from the southern to northern transects, suggesting that juvenile lobsters grow substantially faster in the warmer northern and offshore waters of this fishery. These proportions provide accurate estimates of juvenile growth rates, which are vital in the construction of location‐specific growth algorithms required by the age‐structured models used in the management of this fishery. Model estimates of density‐dependent mortality were greater in the more densely populated centre of the fishery and markedly lower at the northern and southern limits of this species distribution. Annual increases in fishing efficiency were also found to be lowest at the northern and southern extremes of the fishery and greatest in the centre of the fishery, where technology advances and increased fleet mobility have enabled the fleet to increase efficiency by 1–3% each year. Catchability (q) was found to be most influenced by water temperatures in the cooler southern transects, whereas at the Abrolhos Islands, changes in water temperature produced almost no discernable change in q. The catch modelling was also used to quantify the impact of management changes introduced in the 1993/94 fishing season. Increased protection of female lobsters and an 18% pot reduction resulted in a 3–4% permanent reduction in the catch rates of lobsters throughout most of the coastal fishery, whereas at the offshore Abrolhos Islands, catch rates increased by c. 20%, presumably owing to a reduction in the level of pot saturation.

Assessment of the impacts of hydrological fluctuations and salt pans abandonment on Greater flamingos in the Camargue, South of France

Flamingos forage in both commercial salt pans and natural marshes and lagoons along the French Mediterranean coast. In order to assess the impact of changes in management of commercial salt pans and hydrological fluctuations on this flagship species, we evaluated the foraging areas of breeding flamingos using the resightings of 283 breeding flamingos marked with dye at the colony in 1987 and 1989, two years with contrasting hydrological conditions. Teams of observers searched all suitable habitats within 80 km of the colony during the four days following marking and recorded presence of off-duty flamingos. About one-third of the birds were found within 10 km of the colony, but some were seen up to 70 km away. About 24–54% of the birds were found in permanent brackish lagoons and 18–60% in the salt pans, the two most important habitats. In 1989, a dry year with lower water levels in the natural wetlands, the proportion of breeding flamingos using salt pans was twice as high [53%, range (47–60%)] as in 1987 [26%, range (18–29%)], this habitat thus acting as a refuge. Most of the feeding areas shown to be important for flamingos breeding in the Camargue are thus susceptible to variations according to rainfall and to transformations or drying out if the salt pans are abandoned. Our results provide essential benchmarks to reconsider the conservation of this flagship species when management of commercial salt pans changes.

Threshold of tolerability: the impact of management changes to recreational fishing in Ningaloo Marine Park

PurposeThe purpose of this paper is to examine a model for conceptualizing the impacts of environmental management strategies on travel and recreation choice making behavior that considers tolerance thresholds in visitor responses to destination change.Design/methodology/approachA survey involving a sample of 347 regular campers and fishers in the Ningaloo Marine Park, Australia, is analyzed to discern the effect of tolerance thresholds.FindingsDespite widespread dissatisfaction with enlarged sanctuary zones and negative impacts on recreational activities, visitors indicated a high level of satisfaction with their stay. This apparent contradiction is, it is argued, best explained by the threshold of tolerability concept.Research limitations/implicationsIt is argued that recreational users, planning authorities and other stakeholders have a threshold of tolerability in terms of decision‐making concerning management changes. These thresholds mean that changes in management policies, modes of activity and destination travel choices are rarely predictable in their effect, but are bounded by minimal and ideal expectations of destination appeal.Originality/valueThe paper introduces an important concept for tourism research that will aid tourism planning and management authorities in the face of growing environmental pressures caused by overpopulation and climate change.

18F-FDG PET changes management and improves prognostic stratification in patients with colorectal cancer: results of a prospective, multi-centre study

4025 Background: The aims were to: 1) examine the impact of PET in changing management in patients with proven or suspected recurrence of colorectal cancer and, 2) assess the impact of management change on disease free survival. Methods: Symptomatic patients (Group A) with a residual structural lesion suspicious for recurrent tumour, or patients (Group B) with pulmonary or hepatic metastases, which were potentially resectable as determined by conventional imaging, underwent PET scans. Pre- and post-PET management plans were documented blinded to PET results. Patients were followed for 12 months to determine actual management and to assess clinical outcomes. Results: A total of 191 patients (118M:73F, mean age 66 yrs) were recruited. PET detected additional sites of disease in 48.4% of Group A and 43.9% of Group B patients. Importantly, a change in planned management was documented in 65.6% of Group A and 49.0% of Group B patients. Follow-up confirmed implementation of management plans in 96% of patients. Analysis of follow-up data to 12 months post- PET showed that in Group A progressive disease was identified in 60.5% of patients with additional lesions detected on PET compared with conventional imaging, and 36.2% patients with no additional lesions detected by PET (p=0.0364); in Group B progressive disease was identified in 65.9% of patients with additional lesions detected on PET and 39.2% patients with no additional lesions detected by PET (p=0.0198). Patient follow-up also showed that PET provided valuable prognostic information in patients stratified into curative/palliative intent groups. Conclusions: These data unequivocally demonstrate the significant impact of PET on management and outcomes in patients with suspected recurrent colorectal cancer. No significant financial relationships to disclose.

Improved early outcome for end-stage dilated cardiomyopathy in children

Objective To review the impact of management changes on the early outcomes of end-stage dilated cardiomyopathy in children. Methods We conducted a retrospective study of all consecutive children with end-stage dilated cardiomyopathy who received hospital treatment since 1992. Over the past 3 years the following management changes were made: (1) more aggressive use of mechanical cardiac assistance; (2) high priority listing for transplantation; and (3) ABO incompatible transplants for infants. Outcomes for 46 patients admitted between 1992 and 1999 (group I) were compared with 53 patients between 2000 and March 2003 (group II). Results In group I, 12 (26%) patients received mechanical support with recovery in 3 and transplantation in 5 (1 died). In group II, 19 (36%) patients received extracorporeal membrane oxygenation, with recovery in 5 and transplantation in 12 (all survived). The use of mechanical assistance was associated with high morbidity related to bleeding, end-organ failure, and long-term mechanical ventilation. Five patients in group II received ABO incompatible transplants and all survived. There have been no episodes of rejection or need for increased immunosuppressive therapy. Hospital mortality has been significantly reduced (group I, 37% vs group II, 11%; P < .05). Conclusions Recent refinements in the management of end-stage dilated cardiomyopathy in children have significantly reduced early mortality. Identification of markers of early myocardial recovery and development of mechanical devices for longer term and more physiologic support are essential to achieve further improvements in outcome.

Modelling the regional dynamics and management of bovine tuberculosis in New Zealand cattle herds

A previous model addressed the within-herd transmission of bovine Tb ( Mycobacterium bovis) in New Zealand cattle herds. This complementary model considers transmission between herds, in an area of New Zealand's North Island (the Waikato) largely free from wildlife reservoirs. The model is used to account for the observed pattern of Tb breakdowns and to assess the likely impact of changes in management on the percentage of herds on movement control between 1988 and 1993 (an average of 0.76% in the Waikato region). It partitions the region into two sub-areas: one small, with significant infection from wildlife; the other much larger and lacking external sources of infection. The observed pattern of herd breakdowns (in different parts of the Waikato and in the region as a whole) could be accounted for in the model by infection from wildlife reservoirs in the southern sub-area (Waitomo) and infection due to movement of cattle from infected but undiagnosed herds to uninfected herds throughout the whole region. During the above period, the model suggests that about 0.8% of herds became infected each year, that most new infections (81% of the total) occurred between herds in the larger sub-area, and that about 13% of the total occurred through infection from wildlife in the smaller sub-area. The whole situation appears to be in a state of near-neutral balance (even without input of new infection), with removal through testing of new infections almost exactly balancing the rate of infection by between-herd movement. Therefore, if the external input is removed, the number of infected herds and of herds on movement control in the whole region declines so slowly that the decline is almost undetectable. Other management changes had a more dramatic effect – particularly, reducing the testing interval to a maximum of 1 year in the whole district. This also appeared to be a necessary condition for achieving ≤0.2% herds on movement control within 10 years (whatever other strategies were employed). The greatest reduction in the percentage of herds on movement control came from yearly testing plus a 50% reduction in infection from wildlife. A further but smaller additional improvement was gained by reducing cattle movements throughout the region by 50%.

Pulmonary hypertension after operations for congenital heart disease: Analysis of risk factors and management

Background: Management of pulmonary hypertension, a potentially fatal complication of operations to correct congenital heart disease, has evolved through the last 15 years. Monitoring of pulmonary arterial pressure and mixed venous saturation became available, and prophylactic use of α-blockers and other vasodilators increased. This study examines risk factors for morbidity and mortality from pulmonary hypertension after operations to correct congenital heart disease and evaluates the impact of management changes on outcomes. Methods: By means of multivariable logistic regression analysis, 880 high-risk patients with congenital heart disease (of 2484 patients undergoing cardiopulmonary bypass between January 1980 and December 1994) were analyzed to determine which were at risk for postoperative pulmonary hypertension and its associated morbidity and mortality. Results: Patients with atrioventricular canal ( n = 182), truncus arteriosus ( n = 47), total anomalous pulmonary venous connection ( n = 90), transposition of great arteries ( n = 97), hypoplastic left heart syndrome ( n = 50), and ventricular septal defect ( n = 414) demonstrated a higher risk of postoperative pulmonary hypertension. By multivariable logistic regression, preoperative pulmonary hypertension ( p < 0.0001), absence of mixed venous saturation monitoring ( p < 0.0001), and absence of prophylactic α-blockade ( p = 0.0004) significantly increased postoperative pulmonary hypertension. Preoperative pulmonary hypertension ( p < 0.001) and absence of prophylactic α-blockers ( p = 0.0004) were significant risk factors for in-hospital death related to pulmonary hypertension. Repair at older age (except in the case of total anomalous pulmonary venous connection) was a significant risk for postoperative pulmonary hypertension ( p = 0.03). Conclusion: Mixed venous saturation monitoring and α-receptor blockade reduced the incidence of pulmonary hypertension after operations for congenital heart disease. Early definitive repair reduced morbidity and mortality from postoperative pulmonary hypertension. (J T horac C ardiovasc S urg 1996;112:1600-9)

Opportunities for reducing the environmental impact of dairy farming managements: a systems approach

AbstractDairy farming systems are important sources for the emission of a number of materials that include various forms of nitrogen (NO3−, N2O and NH3) with potential environmental impact. The present paper is a systems synthesis study and assesses the likely impact of changes in management on N flows and losses. These include tactical fertilizer adjustment, slurry injection, maize silage production and the use of white clover as an alternative to fertilizer N. Implications for greenhouse gases (N2O and CH4) and support energy have also been considered. Substantial reductions in inputs and total and proportional losses by all die options considered were predicted by this study. Thus, using a tactical approach to fertilizer application and injecting slurry or using 50% maize silage reduced overall N losses from 160 (under conventional management) to 86 and 109kg Nha−1 respectively. Combining both possibilities reduced losses further to 69 kg ha−1. Although use of white clover, especially at low contents in the sward, was the most effective regime to reduce losses, this was at some cost to production so that losses per livestock unit (LU) did not always differ from those under other managements. Changing the N management had consequences for greenhouse gas emission with an estimated maximum 70% reduction in N2O release. The effects on CH4 emissions were relatively small. Substantial reductions in support energy costs were also obtained: these arose mainly from the reduction in fertilizer N use, which represented 66% of the total support energy in the original system.

Partial Budget Model for Reproductive Programs of Dairy Farm Businesses

A partial budget model was developed to investigate the economic impact of management changes for the reproductive program of dairy farm businesses. The model is unique because 1) the herd is split into groups for first lactation and second or greater lactation; 2) each group's days open distribution is employed; 3) a lactation curve simulation is used to estimate a weighted average daily milk production; 4) the current days open distribution is altered by estimating changes in days to first AI, efficiency of estrus detection, and conception rate for the two lactation groups to predict the altered distribution of days open; and 5) the model provides a structure to estimate changes in expenses for labor, feed, supplies and services, and replacement heifers that may occur with the suggested management plan.A microcomputer program was designed based on the partial budget model to support decision making on the dairy farm pertaining to suggested management changes in the reproductive program. When applied to specific case farms, the results of the model indicate that, with improved reproductive efficiency of the milking group, the replacement population increases, and strategies may be required to manage an increased number of replacements. Sensitivity analysis was performed on milk price, feed, and replacement expenses. The case study results indicate that milk price and expenses of raising replacements may have the greatest impact within the partial budget model.

Population Dynamics of the Wild Daffodil (Narcissus Pseudonarcissus): III. Implications of a Computer Model of 1000 Years of Population Change

(1) The consequences of varying the rates of mortality, clonal growth and seed reproduction are explored for a population of Narcissus pseudonarcissus over a 1000-yr period, using a simulation model. The range of values assigned to mortality, clonal growth and seed reproduction was based on rates calculated from field data. (2) When field-based rates of reproduction and mortality were kept constant over a long period, or varied under a simulated coppice cycle, extinction of the population or attainment of unacceptably high densities generally resulted. Stabilization at realistic densities was achieved by modifying values for clonal growth to rates intermediate between the extremes recorded in the field. The clump-size frequency distributions of the simulated stable populations closely matched those derived from field data. (3) At normal rates of fertility and mortality there is a continuous turnover of genets. Increasing the rate of clonal growth increased the probability of genet survival and hence the number of genets (the input of new genets being constant). (4) The development of large clonal clumps occurred only at an unrealistically high rate of clonal growth. This is because increasing density reduces the rate of clonal growth. (5) A low-density pattern of individuals and clumps in Narcissus could be produced by certain combinations of mortality and fertility rate; competition from other plant species or unsuitability of the environment was not required to explain gaps between individuals or clumps. (6) Clumps might consist of the members of more than one genet, as, over a period of several hundred years, a long-lived genet might become dispersed and parts of it come to lie adjacent to other genets. (7) The implications of the results are discussed in relation to the strategies of other woodland perennial herbs and to the impact of management changes in ancient coppiced woodlands.