933 resultados para time dependant cost function


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Parental effort is usually associated with high metabolism that could lead to an increase in the production of reactive oxidative species giving rise to oxidative stress. Since many antioxidants involved in the resistance to oxidative stress can also enhance immune function, an increase in parental effort may diminish the level of antioxidants otherwise involved in parasite resistance. In the present study, we performed brood size manipulation in a population of great tits (Parus major) to create different levels of parental effort. We measured resistance to oxidative stress and used a newly developed quantitative PCR assay to quantify malarial parasitaemia. We found that males with an enlarged brood had significantly higher level of malarial parasites and lower red blood cell resistance to free radicals than males rearing control and reduced broods. Brood size manipulation did not affect female parasitaemia, although females with an enlarged brood had lower red blood cell resistance than females with control and reduced broods. However, for both sexes, there was no relationship between the level of parasitaemia and resistance to oxidative stress, suggesting a twofold cost of reproduction. Our results thus suggest the presence of two proximate and independent mechanisms for the well-documented trade-off between current reproductive effort and parental survival.

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In the administration, planning, design, and maintenance of road systems, transportation professionals often need to choose between alternatives, justify decisions, evaluate tradeoffs, determine how much to spend, set priorities, assess how well the network meets traveler needs, and communicate the basis for their actions to others. A variety of technical guidelines, tools, and methods have been developed to help with these activities. Such work aids include design criteria guidelines, design exception analysis methods, needs studies, revenue allocation schemes, regional planning guides, designation of minimum standards, sufficiency ratings, management systems, point based systems to determine eligibility for paving, functional classification, and bridge ratings. While such tools play valuable roles, they also manifest a number of deficiencies and are poorly integrated. Design guides tell what solutions MAY be used, they aren't oriented towards helping find which one SHOULD be used. Design exception methods help justify deviation from design guide requirements but omit consideration of important factors. Resource distribution is too often based on dividing up what's available rather than helping determine how much should be spent. Point systems serve well as procedural tools but are employed primarily to justify decisions that have already been made. In addition, the tools aren't very scalable: a system level method of analysis seldom works at the project level and vice versa. In conjunction with the issues cited above, the operation and financing of the road and highway system is often the subject of criticisms that raise fundamental questions: What is the best way to determine how much money should be spent on a city or a county's road network? Is the size and quality of the rural road system appropriate? Is too much or too little money spent on road work? What parts of the system should be upgraded and in what sequence? Do truckers receive a hidden subsidy from other motorists? Do transportation professions evaluate road situations from too narrow of a perspective? In considering the issues and questions the author concluded that it would be of value if one could identify and develop a new method that would overcome the shortcomings of existing methods, be scalable, be capable of being understood by the general public, and utilize a broad viewpoint. After trying out a number of concepts, it appeared that a good approach would be to view the road network as a sub-component of a much larger system that also includes vehicles, people, goods-in-transit, and all the ancillary items needed to make the system function. Highway investment decisions could then be made on the basis of how they affect the total cost of operating the total system. A concept, named the "Total Cost of Transportation" method, was then developed and tested. The concept rests on four key principles: 1) that roads are but one sub-system of a much larger 'Road Based Transportation System', 2) that the size and activity level of the overall system are determined by market forces, 3) that the sum of everything expended, consumed, given up, or permanently reserved in building the system and generating the activity that results from the market forces represents the total cost of transportation, and 4) that the economic purpose of making road improvements is to minimize that total cost. To test the practical value of the theory, a special database and spreadsheet model of Iowa's county road network was developed. This involved creating a physical model to represent the size, characteristics, activity levels, and the rates at which the activities take place, developing a companion economic cost model, then using the two in tandem to explore a variety of issues. Ultimately, the theory and model proved capable of being used in full system, partial system, single segment, project, and general design guide levels of analysis. The method appeared to be capable of remedying many of the existing work method defects and to answer society's transportation questions from a new perspective.

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The use of chemicals is a critical part of a pro-active winter maintenance program. However, ensuring that the correct chemicals are used is a challenge. On the one hand, budgets are limited, and thus price of chemicals is a major concern. On the other, performance of chemicals, especially at lower pavement temperatures, is not always assured. Two chemicals that are used extensively by the Iowa Department of Transportation (Iowa DOT) are sodium chloride (or salt) and calcium chloride. While calcium chloride can be effective at much lower temperatures than salt, it is also considerably more expensive. Costs for a gallon of salt brine are typically in the range of $0.05 to $0.10, whereas calcium chloride brine may cost in the range of $1.00 or more per gallon. These costs are of course subject to market forces and will thus change from year to year. The idea of mixing different winter maintenance chemicals is by no means new, and in general discussions it appears that many winter maintenance personnel have from time to time mixed up a jar of chemicals and done some work around the yard to see whether or not their new mix “works.” There are many stories about the mixture turning to “mayonnaise” (or, more colorfully, to “snot”) suggesting that mixing chemicals may give rise to some problems most likely due to precipitation. Further, the question of what constitutes a mixture “working” in this context is a topic of considerable discussion. In this study, mixtures of salt brine and calcium chloride brine were examined to determine their ice melting capability and their freezing point. Using the results from these tests, a linear interpolation model of the ice melting capability of mixtures of the two brines has been developed. Using a criterion based upon the ability of the mixture to melt a certain thickness of ice or snow (expressed as a thickness of melt-water equivalent), the model was extended to develop a material cost per lane mile for the full range of possible mixtures as a function of temperature. This allowed for a comparison of the performance of the various mixtures. From the point of view of melting capacity, mixing calcium chloride brine with salt brine appears to be effective only at very low temperatures (around 0° F and below). However, the approach described herein only considers the material costs, and does not consider application costs or other aspects of the mixture performance than melting capacity. While a unit quantity of calcium chloride is considerably more expensive than a unit quantity of sodium chloride, it also melts considerably more ice. In other words, to achieve the same result, much less calcium chloride brine is required than sodium chloride brine. This is important in considering application costs, because it means that a single application vehicle (for example, a brine dispensing trailer towed behind a snowplow) can cover many more lane miles with calcium chloride brine than with salt brine before needing to refill. Calculating exactly how much could be saved in application costs requires an optimization of routes used in the application of liquids in anti-icing, which is beyond the scope of the current study. However, this may be an area that agencies wish to pursue for future investigation. In discussion with winter maintenance personnel who use mixtures of sodium chloride and calcium chloride, it is evident that one reason for this is because the mixture is much more persistent (i.e. it stays longer on the road surface) than straight salt brine. Operationally this persistence is very valuable, but at present there are not any established methods to measure the persistence of a chemical on a pavement. In conclusion, the study presents a method that allows an agency to determine the material costs of using various mixtures of salt brine and calcium chloride brine. The method is based upon the requirement of melting a certain quantity of snow or ice at the ice-pavement interface, and on how much of a chemical or of a mixture of chemicals is required to do that.

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The expression of calmodulin kinase IV (CaMKIV) can be induced by the thyroid hormone T3 in a time- and concentration-dependent manner at a very early stage of brain differentiation using a fetal rat telencephalon primary cell culture system which can grow and differentiate under chemically defined conditions (Krebs et al. (1996) J. Biol. Chem. 271, 11055-11058). After the induction of CaMKIV by T3 we examined the influence of prolonged absence of T3 from the culture medium on the expression of CaMKIV. We could demonstrate that after the T3-dependent induction of CaMKIV, omission of the hormone, even for 8 days, from the medium did not downregulate the expression of CaMKIV indicating that different regulatory mechanisms became important for the expression of the enzyme. We further showed that CaMKIV could be involved in the Ca(2+) -dependent expression of the immediate early gene c-fos, probably via phosphorylation of the transcription factor CREB. Convergence of signal transduction pathways on this transcription factor by using different protein kinases may explain the importance of CREB for the regulation of different cellular processes.

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The objective of this study was to adapt a nonlinear model (Wang and Engel - WE) for simulating the phenology of maize (Zea mays L.), and to evaluate this model and a linear one (thermal time), in order to predict developmental stages of a field-grown maize variety. A field experiment, during 2005/2006 and 2006/2007 was conducted in Santa Maria, RS, Brazil, in two growing seasons, with seven sowing dates each. Dates of emergence, silking, and physiological maturity of the maize variety BRS Missões were recorded in six replications in each sowing date. Data collected in 2005/2006 growing season were used to estimate the coefficients of the two models, and data collected in the 2006/2007 growing season were used as independent data set for model evaluations. The nonlinear WE model accurately predicted the date of silking and physiological maturity, and had a lower root mean square error (RMSE) than the linear (thermal time) model. The overall RMSE for silking and physiological maturity was 2.7 and 4.8 days with WE model, and 5.6 and 8.3 days with thermal time model, respectively.

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We consider the problem of estimating the mean hospital cost of stays of a class of patients (e.g., a diagnosis-related group) as a function of patient characteristics. The statistical analysis is complicated by the asymmetry of the cost distribution, the possibility of censoring on the cost variable, and the occurrence of outliers. These problems have often been treated separately in the literature, and a method offering a joint solution to all of them is still missing. Indirect procedures have been proposed, combining an estimate of the duration distribution with an estimate of the conditional cost for a given duration. We propose a parametric version of this approach, allowing for asymmetry and censoring in the cost distribution and providing a mean cost estimator that is robust in the presence of extreme values. In addition, the new method takes covariate information into account.

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Residual lung function abnormalities have been investigated in 9 children (4 boys and 5 girls) a mean 2.7 years after surviving severe adult respiratory distress syndrome (ARDS). All patients had been artificially ventilated for an average of 9.4 days with a FiO2 greater than 0.5 for 34 hours and maximal PEEP levels in the range of 8-20 cm H2O. Since the ARDS, 3 children had presented recurrent respiratory symptoms (moderate exertional dyspnea and cough) and 2 had had evidence of fibrosis on chest radiographs. In all patients abnormal lung functions were found, i.e. ventilation inequalities (8), hypoxemia (7), and obstructive (2) and restrictive (1) lung disease. A significant correlation between respirator therapy and residual lung function was found (duration of FiO2 greater than 0.5 in hours and inspiratory plateau pressure during respirator therapy vs. ventilation inequalities and hypoxemia).

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BACKGROUND: Tenofovir is associated with reduced renal function, but it is not clear whether there is a greater decline in renal function when tenofovir is co-administered with a boosted protease inhibitor rather than with a nonnucleoside reverse transcriptase inhibitor (NNRTI). METHODS: We calculated the estimated glomerular filtration rate (eGFR) for patients in the Swiss HIV Cohort Study. We estimated the difference in eGFR over time between first therapies containing tenofovir and either the NNRTI efavirenz or the protease inhibitors lopinavir (LPV/r) or atazanavir (ATV/r), both boosted with ritonavir. RESULTS: Patients on a first therapy of tenofovir co-administered with efavirenz (n  = 484), LPV/r (n = 269) and ATV/r (n =  187) were followed for a median of 1.7, 1.2 and 1.3 years, respectively. Relative to tenofovir and efavirenz, the estimated difference in eGFR for tenofovir and LPV/r was -2.6 ml/min per 1.73 m [95% confidence interval (CI) -7.3 to 2.2) during the first 6 months of therapy, then followed by a difference of 0.0 ml/min per 1.73 m (95% CI -1.1 to 1.1) for each additional 6 months of therapy. Relative to tenofovir and efavirenz, the estimated difference in eGFR for tenofovir and ATV/r was -7.6 ml/min per 1.73 m (95% CI -11.8 to -3.4) during the first 6 months of therapy, then followed by a difference of -0.5 ml/min per 1.73 m (95% CI -1.6 to 0.7) for each additional 6 months of therapy. CONCLUSION: Tenofovir with either boosted protease inhibitor leads to a greater initial decline in eGFR than tenofovir with efavirenz; this decline may be worse with ATV/r than with LPV/r.

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We have characterized the maturation, co- and posttranslational modifications, and functional properties of the alpha(1B)-adrenergic receptor (AR) expressed in different mammalian cells transfected using conventional approaches or the Semliki Forest virus system. We found that the alpha(1B)-AR undergoes N-linked glycosylation as demonstrated by its sensitivity to endoglycosidases and by the effect of tunicamycin on receptor maturation. Pulse-chase labeling experiments in BHK-21 cells demonstrate that the alpha(1B)-AR is synthesized as a 70 kDa core glycosylated precursor that is converted to the 90 kDa mature form of the receptor with a half-time of approximately 2 h. N-Linked glycosylation of the alpha(1B)-AR occurs at four asparagines on the N-terminus of the receptor. Mutations of the N-linked glycosylation sites did not have a significant effect on receptor function or expression. Surprisingly, receptor mutants lacking N-linked glycosylation migrated as heterogeneous bands in SDS-PAGE. Our findings demonstrate that N-linked glycosylation and phosphorylation, but not palmitoylation or O-linked glycosylation, contribute to the structural heterogeneity of the alpha(1B)-AR as it is observed in SDS-PAGE. The modifications found are similar in the different mammalian expression systems explored. Our findings indicate that the Semliki Forest virus system can provide large amounts of functional and fully glycosylated alpha(1B)-AR protein suitable for biochemical and structural studies. The results of this study contribute to elucidate the basic steps involved in the processing of G protein-coupled receptors as well as to optimize strategies for their overexpression.

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The objective of this work was to evaluate the use of a low-cost trap to capture Cerambycidae in different seasons in planted forests in Brazil. Thirty polyethylene-terephthalate trap bottles per hectare were used, disposed at every 50 m. The traps were red painted and contained glass flasks with a mixture of ethanol, methanol and benzaldehyde. There were soap and water at the trap bottom. The traps were checked biweekly for beetle presence. Sampling time required one minute per sample, and traps were easy to use. Total sampling cost, including materials and labor, was US$ 13.46 per sample. Six Cerambycidae species were captured along the dry and rainy seasons.

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Bone morphogenetic proteins (Bmps) regulate the expression of the proneural gene Atoh1 and the generation of hair cells in the developing inner ear. The present work explored the role of Inhibitor of Differentiation genes (Id1-3) in this process. The results show that Id genes are expressed in the prosensory domains of the otic vesicle, along with Bmp4 and Bmp7. Those domains exhibit high levels of the phosphorylated form of Bmp-responding R-Smads (P-Smad1,5,8), and of Bmp-dependent Smad transcriptional activity as shown by the BRE-tk-EGFP reporter. Increased Bmp signaling induces the expression of Id1-3 along with the inhibition of Atoh1. Conversely, the Bmp antagonist Noggin or the Bmp-receptor inhibitor Dorsomorphin elicit opposite effects, indicating that Bmp signaling is necessary for Id expression and Atoh1 regulation in the otocyst. The forced expression of Id3 is sufficient to reduce Atoh1 expression and to prevent the expression of hair cell differentiation markers. Together, these results suggest that Ids are part of the machinery that mediates the regulation of hair cell differentiation exerted by Bmps. In agreement with that, during hair cell differentiation Bmp4 expression, P-Smad1,5,8 levels and Id expression are downregulated from hair cells. However, Ids are also downregulated from the supporting cells which contrarily to hair cells exhibit high levels of Bmp4 expression, P-Smad1,5,8, and BRE-tk-EGFP activity, suggesting that in these cells Ids escape from Bmp/Smad signaling. The differential regulation of Ids in time and space may underlie the multiple functions of Bmp signaling during sensory organ development.

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This report contains an estimate of the cost of highway resurfacing necessitated by damage from studded tires. The total is $95,620,000 for the twenty-five years from 1971 to 1996. This total includes $51,937,000 to resurface pavements and bridges on Interstate routes and $43,683,000 for other Primary highways. The estimate for Interstate routes includes those sections now open to traffic and those planned for completion by November 1974. The estimate for other Primary routes includes rural and municipal sections open to traffic as of November 1970. The estimate was prepared by computing the cost of expected pavement and bridge resurfacing costs for the twenty-five year period assuming continued use of studded tires, then subtracting from this the expected resurfacing ) cost for the same period assuming that the use of' studded tires is prohibited. The total figure, $95,620,000, should be regarded as a conservative estimate of the cost which may be avoided by prohibiting the use of studded tires in Iowa. The conservative nature of the estimate may be demonstrated by the following examples of the guidelines used iri its preparation. 1. Only mainline pavements were included in the cost estimate for the Interstate routes. The connecting loops, exit ramps and entrance ramps at Interstate interchanges contain many additional miles of pavement subject to wear by studded tires. This pavement was omitted from the estimate because reliable ' information about the rate of pavement wear at such locations is not available. As a result, the Interstate resurfacing costs are underestimated. 2. Several other costs were also omitted from the estimate because of a lack of sufficient information. These include the cost of repairing damage caused by studded tires to city streets other than those designated as Primary routes, the damage to pavements and bridges on the more-heavily travelled Secondary roads, and the damage to pavement traffic markings on all highway systems. Experience indicates that portland cement concrete pavements in Iowa have a normal service life of twenty-five years before resurfacing becomes necessary. The service life for asphalt pavements is thirteen years. In making this cost estimate, the need for resurfacing was attributed to wear from studded tires only when the normal service life of the pavement was shortened by that wear. Consequently, this cost estimate does not account for the reduced safety and convenience to Iowa motorists during the time when pavement wear caused by studded tires is significant but less than the critical amount.

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Objectives: To assess the difference in direct medical costs between on-demand (OD) treatment with esomeprazole (E) 20 mg and continuous (C) treatment with E 20 mg q.d. from a clinical practice view in patients with gastroesophageal reflux disease (GERD) symptoms. Methods: This open, randomized study (ONE: on-demand Nexium evaluation) compared two long-term management options with E 20 mg in endoscopically uninvestigated patients seeking primary care for GERD symptoms who demonstrated complete relief of symptoms after an initial treatment of 4 weeks with E 40 mg. Data on consumed quantities of all cost items were collected in the study, while data on prices during the time of study were collected separately. The analysis was done from a societal perspective. Results: Forty-nine percent (484 of 991) of patients randomized to the OD regimen and 46% (420 of 913) of the patients in the C group had at least one contact with the investigator that would have occurred nonprotocol-driven. The difference of the adjusted mean direct medical costs between the treatment groups was CHF 88.72 (95% confidence interval: CHF 41.34-153.95) in favor of the OD treatment strategy (Wilcoxon rank-sum test: P < 0.0001). Adjusted direct nonmedical costs and productivity loss were similar in both groups. Conclusions: The adjusted direct medical costs of a 6-month OD treatment with esomeprazole 20 mg in uninvestigated patients with symptoms of GERD were significantly lower compared with a continuous treatment with E 20 mg once a day. The OD therapy represents a cost-saving alternative to the continuous treatment strategy with E.

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Jasmonates, potent lipid mediators of defense gene expression in plants, are rapidly synthesized in response to wounding. These lipid mediators also stimulate their own production via a positive feedback circuit, which depends on both JA synthesis and JA signaling. To date, molecular components regulating the activation of jasmonate biogenesis and its feedback loop have been poorly characterized. We employed a genetic screen capable of detecting the misregulated activity of 13-lipoxygenase, which operates at the entry point of the jasmonate biosynthesis pathway. Leaf extracts from the Arabidopsis fou2 (fatty acid oxygenation upregulated 2) mutant displayed an increased capacity to catalyze the synthesis of lipoxygenase (LOX) metabolites. Quantitative oxylipin analysis identified less than twofold increased jasmonate levels in healthy fou2 leaves compared to wild-type; however, wounded fou2 leaves strongly increased jasmonate biogenesis compared to wounded wild-type. Furthermore, the plants displayed enhanced resistance to the fungus Botrytis cinerea. Higher than wild-type LOX activity and enhanced resistance in the fou2 mutant depend fully on a functional jasmonate response pathway. The fou2 mutant carries a missense mutation in the putative voltage sensor of the Two Pore Channel 1 gene (TPC1), which encodes a Ca(2+)-permeant non-selective cation channel. Patch-clamp analysis of fou2 vacuolar membranes showed faster time-dependent conductivity and activation of the mutated channel at lower membrane potentials than wild-type. The results indicate that cation fluxes exert strong control over the positive feedback loop whereby JA stimulates its own synthesis.

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BACKGROUND: Dried blood spots (DBS) sampling has gained popularity in the bioanalytical community as an alternative to conventional plasma sampling, as it provides numerous benefits in terms of sample collection and logistics. The aim of this work was to show that these advantages can be coupled with a simple and cost-effective sample pretreatment, with subsequent rapid LC-MS/MS analysis for quantitation of 15 benzodiazepines, six metabolites and three Z-drugs. For this purpose, a simplified offline procedure was developed that consisted of letting a 5-µl DBS infuse directly into 100 µl of MeOH, in a conventional LC vial. RESULTS: The parameters related to the DBS pretreatment, such as extraction time or internal standard addition, were investigated and optimized, demonstrating that passive infusion in a regular LC vial was sufficient to quantitatively extract the analytes of interest. The method was validated according to international criteria in the therapeutic concentration ranges of the selected compounds. CONCLUSION: The presented strategy proved to be efficient for the rapid analysis of the selected drugs. Indeed, the offline sample preparation was reduced to a minimum, using a small amount of organic solvent and consumables, without affecting the accuracy of the method. Thus, this approach enables simple and rapid DBS analysis, even when using a non-DBS-dedicated autosampler, while lowering the costs and environmental impact.