Overview of the tuning template for radiography in Europe

HENRE II (Higher Education Network for Radiography in Europe)

Cognitive models for the concept of angle

Tese de doutoramento em Filosofia

Sistema de localização indoor com base no protocolo ZIGBEE

Actualmente, os sistemas de localização são uma área em forte expansão sendo que para espaços exteriores existe uma grande variedade de sistemas de localização enquanto que para espaços interiores as soluções são mais escassas. Este trabalho apresenta o estudo e implementação de um sistema de localização indoor baseado no protocolo ZigBee, utilizando a informação da intensidade de sinal recebido (RSSI - Received Signal Strength Indication). Para a realização deste projecto foi necessário iniciar uma pesquisa mais pormenorizada do protocolo ZigBee. O dispositivo móvel a ser localizado é o módulo XBee Serie 2 que se baseia no mesmo protocolo. Posto isto, foi necessário efectuar um estudo sobre sistemas de localização existentes e analisar as técnicas de localização utilizadas para ambientes interiores. Desta forma utiliza-se neste projecto uma técnica que consiste na análise de fingerprinting, onde é criado um mapa com os valores RSSI para diferentes coordenadas do espaço físico. As intensidades de sinal recebido são relativas a dispositivos XBee instalados em pontos fixos de referência. Para calcular a localização do dispositivo móvel é utilizado o algoritmo K-NN (K- Nearest Neighbors) que permite estimar a posição aproximada do dispositivo móvel. Por último é descrito todo o desenvolvimento do projecto assim como a apresentação e discussão de resultados.

Harvest control rule vs optimal harvesting of an age-structured population: The case of the Ibero-Atlantic Sardine Fishery

Research Masters

Status of radiation protection at different hospitals in Nepal.

Nepal has a long history of medical radiology since1923 but unfortunately, we still do not have any Radiation Protection Infrastructure to control the use of ionizing radiations in the various fields. The objective of this study was an assessment of the radiation protection in medical uses of ionizing radiation. Twenty-eight hospitals with diagnostic radiology facility were chosen for this study according to patient loads, equipment and working staffs. Radiation surveys were also done at five different radiotherapy centers. Questionnaire for radiation workers were used; radiation dose levels were measured and an inventory of availability of radiation equipment made. A corollary objective of the study was to create awareness in among workers on possible radiation health hazard and risk. It was also deemed important to know the level of understanding of the radiation workers in order to initiate steps towards the establishment of Nepalese laws, regulation and code of radiological practice in this field. Altogether, 203 Radiation workers entertained the questionnaire, out of which 41 are from the Radiotherapy and 162 are from diagnostic radiology. The radiation workers who have participated in the questionnaire represent more than 50% of the radiation workers working in this field in Nepal. Almost all X-ray, CT and Mammogram installations were built according to protection criteria and hence found safe. Radiation dose level at the reference points for all the five Radiotherapy centers are within safe limit. Around 65% of the radiation workers have never been monitored for radiation. There is no quality control program in any of the surveyed hospitals except radiotherapy facilities.

Do the Wealthy Risk More Money? An Experimental Comparison

Are poor people more or less likely to take money risks than wealthy folks? We find that risk attraction is more prevalent among the wealthy when the amounts of money at risk are small (not surprising, since ten dollars is a smaller amount for a wealthy person than for a poor one), but, interestingly, for the larger amounts of money at risk the fraction of the nonwealthy displaying risk attraction exceeds that of the wealthy. We also replicate our previous finding that many people display risk attraction for small money amounts, but risk aversion for large ones. We argue that preferences yielding risk attraction for small money amounts, together with risk aversion for larger amounts, at all levels of wealth, while contradicting the expected utility hypothesis, may be well-defined, independently of reference points, on the choice space.

The value of useless information

There are many situations in which individuals have a choice of whether or notto observe eventual outcomes. In these instances, individuals often prefer to remainignorant. These contexts are outside the scope of analysis of the standard vonNeumann-Morgenstern (vNM) expected utility model, which does not distinguishbetween lotteries for which the agent sees the final outcome and those for which hedoes not. I develop a simple model that admits preferences for making an observationor for remaining in doubt. I then use this model to analyze the connectionbetween preferences of this nature and risk-attitude. This framework accommodatesa wide array of behavioral patterns that violate the vNM model, and thatmay not seem related, prima facie. For instance, it admits self-handicapping, inwhich an agent chooses to impair his own performance. It also accommodatesa status quo bias without having recourse to framing effects, or to an explicitdefinition of reference points. In a political economy context, voters have strictincentives to shield themselves from information. In settings with other-regardingpreferences, this model predicts observed behavior that seems inconsistent witheither altruism or self-interested behavior.

Do the eealthy risk more money? An experimental comparison

Are poor people more or less likely to take money risks than wealthy folks?We find that risk attraction is more prevalent among the wealthy when theamounts of money at risk are small (not surprising, since ten dollars is asmaller amount for a wealthy person than for a poor one), but, interestingly,for the larger amounts of money at risk the fraction of the nonwealthydisplaying risk attraction exceeds that of the wealthy.We also replicate our previous finding that many people display riskattraction for small money amounts, but risk aversion for large ones. Weargue that preferences yielding risk attraction for small money amounts,together with risk aversion for larger amounts, at all levels of wealth, while contradicting the expected utility hypothesis, may be well-defined,independently of reference points, on the choice space.

Exporting Contours to DICOM-RT Structure Set

This paper presents an ITK implementation for exportingthe contours of the automated segmentation results toDICOM-RT Structure Set format. The âeurooeradiotherapystructure setâeuro (RTSTRUCT) object of the DICOM standard isused for the transfer of patient structures and relateddata, between the devices found within and outside theradiotherapy department. It mainly contains theinformation of regions of interest (ROIs) and points ofinterest (E.g. dose reference points). In many cases,rather than manually drawing these ROIs on the CT images,one can indeed benefit from the automated segmentationalgorithms already implemented in ITK. But at present, itis not possible to export the ROIs obtained from ITK toRTSTRUCT format. In order to bridge this gap, we havedeveloped a framework for exporting contour data toRTSTRUCT. We provide here the complete implementation ofRTSTRUCT exporter and present the details of the pipelineused. Results on a 3-D CT image of the Head and Neck(H&N) region are presented.

Flood of May 19, 1990, Along Perry Creek in Plymouth and Woodbury Counties, Iowa, HR-140, 1996

A water-surface-elevation profile and peak discharges for the flood of May 19, 1990, along Perry Creek in Plymouth and Woodbury Counties, Iowa, are presented in this report. The peak discharge for the May 19, 1990, flood on Perry Creek at 38th Street, Sioux City (06600000) is the second largest flood-peak discharge recorded at the streamflow-gaging station for the period 1939-95. The peak discharge for May 19, 1990, of 8,670 cubic feet per second, is approximately equal to the 35-year recurrence-interval discharge. The report provides information on flood stages and discharges and floodflow frequencies for streamflow- gaging stations in the Perry Creek Basin using flood information collected during 1939-95. Information on temporary bench marks and reference points established in the Perry Creek Basin during 1990-93 is also included in the report. A flood history describes rainfall conditions for the three largest floods that occurred during 1939-95 (July 1944, September 1949, and May 1990).

Floods of July 19-25, 1999, in the Wapsipinicon and Cedar River Basins, Northeast Iowa, HR-140

Severe flooding occurred during July 19-25, 1999, in the Wapsipinicon and Cedar River Basins following two thunderstorms over northeast Iowa. During July 18-19, as much as 6 inches ofrainfall was centered over Cerro Gordo, Floyd, Mitchell, and Worth Counties. During July 20-21, a second storm occurred in which an additional rainfall of as much as 8 inches was centered over Chickasaw and Floyd Counties. The cumulative effect of the storms produced floods with new maximum peak discharges at the following streamflow-gaging stations: Wapsipinicon River near Tripoli, 19,400 cubic feet per second; Cedar River at Charles City, 31,200 cubic feet per second (recurrence interval about 90 years); Cedar River at Janesville, 42,200 cubic feet per second (recurrence interval about 80 years); and Flood Creek near Powersville, 19,000 cubic feet per second. Profiles of flood elevations for the July 1999 flood are presented in this report for selected reaches along the Wapsipinicon, Cedar, and Shell Rock Rivers and along Flood Creek. Information about the river basins, rain storms, and flooding are presented along with information on temporary bench marks and reference points in the Wapsipinicon and Cedar River Basins.

Floods of September 15-16, 1992, in the Thompson, Weldon, and Chariton River Basins, South-Central Iowa, HR-140, 1997

Water-surface-elevation profiles and peak discharges for the floods of September 15-16, 1992, in the Thompson, Weldon, and Chariton River Basins, south-central Iowa, are presented in this report. The profiles illustrate the 1992 floods along the Thompson, Weldon, Chariton, and South Fork Chariton Rivers and along Elk Creek in the south-central Iowa counties of Adair, Clarke, Decatur, Lucas, Madison, Ringgold, Union, and Wayne. Water-surface-elevation profiles for the floods of July 4, 1981, along the Chariton River in Lucas County and along the South Fork Chariton River in Wayne County also are included in the report for comparative purposes. The September 15-16, 1992, floods are the largest known peak discharges at gaging stations Thompson River at Davis City (station number 06898000) 57,000 cubic feet per second, Weldon River near Leon (station number 06898400) 76,200 cubic feet per second, Chariton River near Chariton (station number 06903400) 37,700 cubic feet per second, and South Fork Chariton River near Promise City (station number 06903700) 70,600 cubic feet per second. The peak discharges were, respectively, 1.7, 2.6, 1.4, and 2.1 times larger than calculated 100-year recurrence-interval discharges. The report provides information on flood stages and discharges and floodflow frequencies for streamflow-gaging stations in the Thompson, Weldon, and Chariton River Basins using flood information collected through 1995. Information on temporary bench marks and reference points established in the Thompson and Weldon River Basins during 1994-95, and in the Chariton River Basin during 1983-84 and 1994-95, also is included in the report. A flood history summarizes rainfall conditions and damages for floods that occurred during 1947, 1959, 1981, 1992, and 1993.

Floods of July 12, 1972, March 19, 1979, and June 15, 1991, in the Turkey River, Northeast Iowa, HR-140, 1996

Water-surface-elevation profiles and peak discharges for the floods of July 12, 1972, March 19, 1979, and June 15, 1991, in the Turkey River Basin, northeast Iowa, are presented in this report. The profiles illustrate the 1979 and 1991 floods along the Turkey River in Fayette and Clayton Counties and along the Volga River in Clayton County; the 1991 flood along Roberts Creek in Clayton County and along Otter Creek in Fayette County; and the 1972 flood along the Turkey River in Winneshiek and Fayette Counties. Watersurface elevations for the flood of March 19, 1979, were collected by the Iowa Natural Resources Council. The June 15, 1991, flood on the Turkey River at Garber (station number 05412500) is the largest known flood-peak discharge at the streamflow-gaging station for the period 1902-95. The peak discharge for June 15, 1991, of 49,900 cubic feet per second was 1.4 times larger than the 100-year recurrence-interval discharge. The report provides information on flood stages and discharges and floodflow frequencies for streamflow-gaging stations in the Turkey River Basin using flood information collected during 1902-95. Information on temporary bench marks and reference points established in the Turkey River Basin during 1981, 1992, and 1996 also is included in the report. A flood history describes rainfall conditions for floods that occurred during 1922, 1947, 1972, 1979, and 1991.

Goal setting and monetary incentives: when large stakes are not enough

The aim of this paper is to test the effectiveness of wage-irrelevant goal setting policies in a laboratory environment. In our design, managers can assign a goal to their workers by setting a certain level of performance on the work task. We establish our theoretical conjectures by developing a model where assigned goals act as reference points to workers’ intrinsic motivation. Consistent with our model, we find that managers set goals which are challenging but attainable for an average-ability worker. Workers respond to these goals by increasing effort, performance and by decreasing on-the-job leisure activities with respect to the no-goal setting baseline. Finally, we study the interaction between goal setting and monetary rewards and find that goal setting is most effective when monetary incentives are strong. These results suggest that goal setting may produce intrinsic motivation and increase workers’ performance beyond what is achieved using solely monetary incentives.

Modeling and mitigation of supply-demand mismatches

In this thesis, I develop analytical models to price the value of supply chain investments under demand uncer¬tainty. This thesis includes three self-contained papers. In the first paper, we investigate the value of lead-time reduction under the risk of sudden and abnormal changes in demand forecasts. We first consider the risk of a complete and permanent loss of demand. We then provide a more general jump-diffusion model, where we add a compound Poisson process to a constant-volatility demand process to explore the impact of sudden changes in demand forecasts on the value of lead-time reduction. We use an Edgeworth series expansion to divide the lead-time cost into that arising from constant instantaneous volatility, and that arising from the risk of jumps. We show that the value of lead-time reduction increases substantially in the intensity and/or the magnitude of jumps. In the second paper, we analyze the value of quantity flexibility in the presence of supply-chain dis- intermediation problems. We use the multiplicative martingale model and the "contracts as reference points" theory to capture both positive and negative effects of quantity flexibility for the downstream level in a supply chain. We show that lead-time reduction reduces both supply-chain disintermediation problems and supply- demand mismatches. We furthermore analyze the impact of the supplier's cost structure on the profitability of quantity-flexibility contracts. When the supplier's initial investment cost is relatively low, supply-chain disin¬termediation risk becomes less important, and hence the contract becomes more profitable for the retailer. We also find that the supply-chain efficiency increases substantially with the supplier's ability to disintermediate the chain when the initial investment cost is relatively high. In the third paper, we investigate the value of dual sourcing for the products with heavy-tailed demand distributions. We apply extreme-value theory and analyze the effects of tail heaviness of demand distribution on the optimal dual-sourcing strategy. We find that the effects of tail heaviness depend on the characteristics of demand and profit parameters. When both the profit margin of the product and the cost differential between the suppliers are relatively high, it is optimal to buffer the mismatch risk by increasing both the inventory level and the responsive capacity as demand uncertainty increases. In that case, however, both the optimal inventory level and the optimal responsive capacity decrease as the tail of demand becomes heavier. When the profit margin of the product is relatively high, and the cost differential between the suppliers is relatively low, it is optimal to buffer the mismatch risk by increasing the responsive capacity and reducing the inventory level as the demand uncertainty increases. In that case, how¬ever, it is optimal to buffer with more inventory and less capacity as the tail of demand becomes heavier. We also show that the optimal responsive capacity is higher for the products with heavier tails when the fill rate is extremely high.