Forecasting seat sales in passenger airlines: introducing the round-trip model

This thesis aims to improve sales forecasting in the context of passenger airlines. We study two important issues that could potentially improve forecasting accuracy: day-to-day price change rather than price itself, and linking flights that are likely to be considered as pairs for a round trip by passengers; we refer to the latter as the Round-Trip Model (RTM). We find that price change is a significant variable regardless of days remaining to flight in the last three weeks to flight departure, which opens the possibility of planning for revenue maximizing price change patterns. We also find that the RTM can improve the precision of the forecasting models, and provide an improved pricing strategy for planners. In the study of the effect of price change on sales, analysis of variance is applied; finite regression mixture models were tested to identify linked traffic in the two directions and the linked flights on a route in reverse directions; adaptive neuro-fuzzy inference system (ANFIS) is applied to develop comparative models for studying sales effect between price and price change, and one-way versus round-trip models. The price change model demonstrated more robust results with comparable estimation errors, and the concept model for the round-trip with only one linked flight reduced estimation error by 5%. This empirical study is performed on a database with 22,900 flights which was obtained from a major North American passenger airline

Theoretical and Experimental Investigation of Switch-Like Responses Arising from Multisite Protein Phosphorylation.

Switch-like responses are important regulatory features of biological processes involving binary decisions such as cell division. Multisite protein phosphorylation is a proposed mechanism for achieving switch-like behaviors. For example, it is conjectured that the G1/S transition of the yeast cell cycle occurs in a switch-like fashion due to multisite phosphorylation-triggered degradation of the Sic1 protein. The objective of this dissertation is first to acquire a quantitative and predictive understanding of switch-like behaviors arising from multisite phosphorylation in natural systems, and second to employ this knowledge for the design of synthetic protein devices. We first developed a mathematical model to investigate systematically the role of multisite phosphorylation in the phosphorylation-triggered degradation process of a protein like Sic1. We found that as the number of sites increases, a more switch-like temporal profile can be generated. The steepness is determined synergistically by various factors, including the total number of sites and kinetic parameters. To test our theoretical predictions, we examined the steady-state response of wild-type and mutant Sic1 with various numbers of phosphorylation sites. It was observed that the response of Sic1, measured by its binding to a downstream protein Cdc4 in the degradation pathway, to the Cln2-Cdc28 kinase in vitro is switch-like. Furthermore, the ultrasensitivity decreases as the number of sites decreases. We next showed, through computational analysis, that a multisite protein can exhibit sustainable and tunable oscillations when embedded in a negative feedback loop, formed via inhibition of the rst phosphorylation step. We also designed a protein degradation device based on multiple protein binding domains and carried out preliminary study of its implementation. Our work demonstrates the potential of utilizing multisite proteins or the broader design principle of intramolecular multiple interaction modules, which provides an effective and flexible means for generating high nonlinearity, in creating a wide range of synthetic biological devices. This dissertation suggests quantitative design principles for switch-like stimulusresponse relationships arising from multisite protein phosphorylation, which might be a widespread mechanism in cellular regulation. In addition, our results provide intriguing hypotheses to be investigated experimentally in future work, such as the critical effect of multi-step phosphorylation kinetics.Ph.D.Chemical EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/89620/1/varedi_1.pd

Hydatidosis of the Pelvic Cavity: A Big Masquerade

We report and discuss a case of primary hydatidosis of the pelvic cavity in a woman who presented with severe weight loss and abdominal pain. This unusual presentation was initially considered as a tumor process until surgical exploration and microscopic studies confirmed the diagnosis. The gynecologists should be aware of possibility of primary hydatid cyst of the pelvic cavity and should be considered in the differential diagnosis of cystic pelvic masses, especially in areas where the disease is endemic

Hydrology and hydrobiology data analysis collected during 1998-2007

Annually, many data of hydrology and hydrobiology of the southern Caspian Sea at Iran's coasts were collected by Caspian Sea Research Institute of Ecology. The data which had been collected by researchers submitted annually in several reports but has not been processed all at once. Fluctuations of various parameters were surveyed and the relationships between them were analyzed. The main goal of this research is to analysis the data were obtained from 1994 to 2006 and show changes the concentration of various parameters in the Caspian Sea. Physicochemical data indicated that the average trend of transparency and salinity was decreased from 1994 to 2006 annually, where the salinity value was decreased from 12.37 ppt (part per thousand) to 11.5 ppt. The average of dissolved oxygen was increased from 6.4 to 8.6mg/l. pH has slightly fluctuated from 8.15 to 8.31. However, with increasing depth from surface to bottom, the average of dissolved oxygen was sharply decreased (DO concentration in surface and 800 m was 7.18 and 1.45 mg/l, respectively). The trend of salinity and pH fluctuation was very slow with depth but the salinity has an increasing with incrementing of depth but pH has a decreased trend. The average of organic and inorganic phosphorus and TP was nearly increased. The average of Nitrate and Silica sharply increased comparing to depth but the average of Nitrite and organic Nitrogen decreased. The results showed that the temperature fluctuation in different water layers was low in winter but the dramatic decreasing of temperature was occurred at 10-20 m (in spring), 20-50 m (in winter) and 50-100 m (in autumn). With increasing of depth (Slope of the Sea), transparency and salinity values have an increasing while DO and pH showed decreased. As a whole, 335 species of phytoplankton were identified, there are 70 species in advance as these species were not seen in this period but 96 of novel's species have been recorded. The lowest and the most of phytoplankton biomass was recorded in 2006 and 2001 while the biomass was 59 and 1034 mg/m^3, respectively. Albet, the lowest biomass was recorded at the depth of 100 m (24.1 mg/m^3) but the maximum was observed in surface layer (1344.1 mg/m^3). The average of phytoplankton biomass was increased after arrival of the ctenophore. There was a significant difference between the average of biomass in different seasons before and after of the ctenophore invasion (P0.137, P>0.782). Before the presence of ctenophore, the worms had been constituted a dominate group with an approximately %45 of total abundance and also %20 of their biomass. After this period, their frequency was sharply increased (more than %85) but the maximum value pertains to Cardidae (more than %90). The species diversity, evenness and richness were varied between .69-2.51, 0.23-0.63 and .011-3.79, respectively. AMBI software, Shanon-Viner parameter was moderate in all seasons from 1994 to 1996 but this parameter was reduced in a bad limit (boundary) in the most seasons from 2002 to 2005. The main parameter of M-AMBI consists of several parameters and also approximately showed similar changes such as Shanon -viner parameter. On basis of this parameter, the ecological quality condition of Caspian Sea was superior limit in all seasons from 1994 to 1996 but after the following years were decreased from good to moderate limits (After the presence of ctenophore). Relationship between abiotic variants and phytoplankton indicated that there was a direct relationship between transparency and salinity while there was a powerful and reversal significant relationship between transparency water temperature, transparency in organic Nitrate, phytoplankton number and transparency phytoplankton biomass. The comparison between different variants average in two periods (before and after the ctenophore invasion) indicated that the average of Kilka catch was decreased, the relative frequency of clupeonella engrauliformis and clupenoella grimmi was sharply reduced but the relative frequency of Clupeonella cultriventris was sharply increased, the species diversity, evenness and richness and the number of zooplankton species were sharply decreased, the average of biomass and transparency was sharply reduced, the average of dissolved oxygen and liza saliens or liza auratus catch were increased. These difference were often significant (P<0.05). Therefore, with the ctenophore invasion into the Caspian Sea, the primary production was increased, the biomass value of zooplankton and specially Kilka which fed on zooplankton were sharply decreased while the fish such as Rutilus frisii kutum and mullet (Liza salins or Liza aurratus) which fed on benthic were increased

The study of pollution in the Gorgan bay

From an environmental standpoint bays around the world are very important ecosystems including the Gulf of Gorgan Bay and thus are important. Which has a relatively low depth, a little flow, temperature appropriate, biogenic materials and abundant food in the sea suitable for children sometimes place (Nursery ground) and also the perfect place for power (Fattening ground) is an early sea fish. In this research effort will be the initial studies on the impact of environmental pollutants on the ecosystem of the Gulf of Gorgan and the quality and quantity of pollution, especially pollution, agricultural pesticides and entering the Gulf of Gorgan and the impact on the ecosystem's the initial assessment and the monitoring of changes in them over the years. The user in the Gulf of Gorgan, agriculture. Pollution from agricultural fields related to pesticides and fertilizers are used in the fields. According to consumer research, and the remaining amount of pesticides in water and sediments of the Gulf of measured, indicated that most of the remains of chlorinated pesticides in sediments of the pesticides used in the agricultural sector In addition, all the toxins in the summer and spring peak. In addition, the DDE concentration compared to other poisons. In the case of other contaminants in the area is now threatened by the Gulf of Gorgan, although not serious, but it seems that the increase in organic matter and reduce the amount of oxygen of the water. The near future to Eutrofication risks in the ecosystem