285 research outputs found
Weighted entropy and optimal portfolios for risk-averse Kelly investments
Following a series of works on capital growth investment, we analyse
log-optimal portfolios where the return evaluation includes `weights' of
different outcomes. The results are twofold: (A) under certain conditions, the
logarithmic growth rate leads to a supermartingale, and (B) the optimal
(martingale) investment strategy is a proportional betting. We focus on
properties of the optimal portfolios and discuss a number of simple examples
extending the well-known Kelly betting scheme.
An important restriction is that the investment does not exceed the current
capital value and allows the trader to cover the worst possible losses.
The paper deals with a class of discrete-time models. A continuous-time
extension is a topic of an ongoing study
Analysis of Kelly-optimal portfolios
We investigate the use of Kelly's strategy in the construction of an optimal
portfolio of assets. For lognormally distributed asset returns, we derive
approximate analytical results for the optimal investment fractions in various
settings. We show that when mean returns and volatilities of the assets are
small and there is no risk-free asset, the Kelly-optimal portfolio lies on
Markowitz Efficient Frontier. Since in the investigated case the Kelly approach
forbids short positions and borrowing, often only a small fraction of the
available assets is included in the Kelly-optimal portfolio. This phenomenon,
that we call condensation, is studied analytically in various model scenarios.Comment: 15 pages, 7 figures; extended list of references and some minor
modification
Design and feasibility testing of a novel group intervention for young women who binge drink in groups
BackgroundYoung women frequently drink alcohol in groups and binge drinking within these natural drinking groups is common. This study describes the design of a theoretically and empirically based group intervention to reduce binge drinking among young women. It also evaluates their engagement with the intervention and the acceptability of the study methods.MethodsFriendship groups of women aged 18–35 years, who had two or more episodes of binge drinking (>6 UK units on one occasion; 48g of alcohol) in the previous 30 days, were recruited from the community. A face-to-face group intervention, based on the Health Action Process Approach, was delivered over three sessions. Components of the intervention were woven around fun activities, such as making alcohol free cocktails. Women were followed up four months after the intervention was delivered. Results The target of 24 groups (comprising 97 women) was recruited. The common pattern of drinking was infrequent, heavy drinking (mean consumption on the heaviest drinking day was UK 18.1 units). Process evaluation revealed that the intervention was delivered with high fidelity and acceptability of the study methods was high. The women engaged positively with intervention components and made group decisions about cutting down. Twenty two groups set goals to reduce their drinking, and these were translated into action plans. Retention of individuals at follow up was 87%.ConclusionsThis study successfully recruited groups of young women whose patterns of drinking place them at high risk of acute harm. This novel approach to delivering an alcohol intervention has potential to reduce binge drinking among young women. The high levels of engagement with key steps in the behavior change process suggests that the group intervention should be tested in a full randomised controlled trial
Minería de datos para el descubrimiento de patrones en enfermedades respiratorias en Bogotá, Colombia
Trabajo de InvestigaciónEl presente proyecto se basa en la aplicación de minería de datos mediante el algoritmo de clustering K- means que permita la generación de un modelo descriptivo con el análisis de los datos y con el objetivo de identificar posibles comportamientos en enfermedades respiratorias en la ciudad de Bogotá.
El conjunto de clústeres generados por la herramienta RapidMiner es la
recopilación de datos de un periodo de cinco años de 2012 a 2016, en donde se contemplan el número de casos asociados a 184 diagnósticos de enfermedades respiratorias y la edad de los pacientes corresponde de 0 a 5 años.Trabajo de Investigación1. GENERALIDADES
2. OBJETIVOS
3. JUSTIFICACIÓN
4. DELIMITACIÓN
5. MARCO REFERENCIAL
6. METODOLOGÍA
7. FUENTES DE EXTRACCIÓN Y SUS VARIABLES
8. DISEÑO
9. SELECCIÓN DE ALGORITMOS DE CLUSTERING
10. RECONOCER PATRONES A PARTIR DE LA INFORMACIÓN RECOPILADA
11. CONCLUSIONES
12. TRABAJOS FUTUROS 13. REFERENCIAS BIBLIOGRÁFICAS
14. ANEXOSPregradoIngeniero de Sistema
A synthesis of past, current and future research for protection and management of papyrus (Cyperus papyrus L.) wetlands in Africa
Papyrus wetlands (dominated by the giant
sedge Cyperus papyrus L.) occur throughout eastern,
central and southern Africa and are important for
biodiversity, for water quality and quantity regulation
and for the livelihoods of millions of people. To draw
attention to the importance of papyrus wetlands, a
special session entitled ‘‘The ecology of livelihoods in
papyrus wetlands’’ was organized at the 9th INTECOL
Wetlands Conference in Orlando, Florida in June
2012. Papers from the session, combined with additional
contributions, were collected in a special issue
of Wetlands Ecology and Management. The current
paper reviews ecological and hydrological characteristics
of papyrus wetlands, summarizes their ecosystem
services and sustainable use, provides an
overview of papyrus research to date, and looks at
policy development for papyrus wetlands. Based on
this review, the paper provides a synthesis of research
and policy priorities for papyrus wetlands and introduces
the contributions in the special issue. Main
conclusions are that (1) there is a need for better
estimates of the area covered by papyrus wetlands.
Limited evidence suggests that the loss of papyrus
wetlands is rapid in some areas; (2) there is a need for a
better understanding and modelling of the regulating
services of papyrus wetlands to support trade-off
analysis and improve economic valuation; (3) research
on papyrus wetlands should include assessment of all
ecosystem services (provisioning, regulating, habitat,
cultural) so that trade-offs can be determined as the
basis for sustainable management strategies (‘wise
use’); (4) more research on the governance, institutional
and socio-economic aspects of papyrus wetlands
is needed to assist African governments in
dealing with the challenges of conserving wetlands in
the face of growing food security needs and climate
change. The papers in the special issue address a
number of these issues
Nutrition and lung cancer: a case control study in Iran
Background: Despite many prospective and retrospective studies about the association of dietary habit and lung
cancer, the topic still remains controversial. So, this study aims to investigate the association of lung cancer with
dietary factors.
Method: In this study 242 lung cancer patients and their 484 matched controls on age, sex, and place of residence
were enrolled between October 2002 to 2005. Trained physicians interviewed all participants with standardized
questionnaires. The middle and upper third consumer groups were compared to the lower third according to the
distribution in controls unless the linear trend was significant across exposure groups.
Result: Conditional logistic regression was used to evaluate the association with lung cancer. In a multivariate
analysis fruit (Ptrend < 0.0001), vegetable (P = 0.001) and sunflower oil (P = 0.006) remained as protective factors and
rice (P = 0.008), bread (Ptrend = 0.04), liver (P = 0.004), butter (Ptrend = 0.04), white cheese (Ptrend < 0.0001), beef
(Ptrend = 0.005), vegetable ghee (P < 0.0001) and, animal ghee (P = 0.015) remained as risk factors of lung cancer.
Generally, we found positive trend between consumption of beef (P = 0.002), bread (P < 0.0001), and dairy
products (P < 0.0001) with lung cancer. In contrast, only fruits were inversely related to lung cancer (P < 0.0001).
Conclusion: It seems that vegetables, fruits, and sunflower oil could be protective factors and bread, rice, beef,
liver, dairy products, vegetable ghee, and animal ghee found to be possible risk factors for the development of
lung cancer in Iran
Multidimentional proteomics for cell biology
The proteome is a dynamic system in which each protein has interconnected properties — dimensions — that together contribute to the phenotype of a cell. Measuring these properties has proved challenging owing to their diversity and dynamic nature. Advances in mass spectrometry-based proteomics now enable the measurement of multiple properties for thousands of proteins, including their abundance, isoform expression, turnover rate, subcellular localization, post-translational modifications and interactions. Complementing these experimental developments are new data analysis, integration and visualization tools as well as data-sharing resources. Together, these advances in the multidimensional analysis of the proteome are transforming our understanding of various cellular and physiological processes
Pain relief in labour: a qualitative study to determine how to support women to make decisions about pain relief in labour
Background
Engagement in decision making is a key priority of modern healthcare. Women are encouraged to make decisions about pain relief in labour in the ante-natal period based upon their expectations of what labour pain will be like. Many women find this planning difficult. The aim of this qualitative study was to explore how women can be better supported in preparing for, and making, decisions during pregnancy and labour regarding pain management.
Methods
Semi-structured interviews were conducted with 13 primiparous and 10 multiparous women at 36 weeks of pregnancy and again within six weeks postnatally. Data collection and analysis occurred concurrently to identify key themes.
Results
Three main themes emerged from the data. Firstly, during pregnancy women expressed a degree of uncertainty about the level of pain they would experience in labour and the effect of different methods of pain relief. Secondly, women reflected on how decisions had been made regarding pain management in labour and the degree to which they had felt comfortable making these decisions. Finally, women discussed their perceived levels of control, both desired and experienced, over both their bodies and the decisions they were making.
Conclusion
This study suggests that the current approach of antenatal preparation in the NHS, of asking women to make decisions antenatally for pain relief in labour, needs reviewing. It would be more beneficial to concentrate efforts on better informing women and on engaging them in discussions around their values, expectations and preferences and how these affect each specific choice rather than expecting them to make to make firm decisions in advance of such an unpredictable event as labour
Cardiovascular disease, chronic kidney disease, and diabetes mortality burden of cardiometabolic risk factors from 1980 to 2010: a comparative risk assessment
Background High blood pressure, blood glucose, serum cholesterol, and BMI are risk factors for cardiovascular
diseases and some of these factors also increase the risk of chronic kidney disease and diabetes. We estimated mortality from cardiovascular diseases, chronic kidney disease, and diabetes that was attributable to these four
cardiometabolic risk factors for all countries and regions from 1980 to 2010.
Methods We used data for exposure to risk factors by country, age group, and sex from pooled analyses of populationbased health surveys. We obtained relative risks for the eff ects of risk factors on cause-specifi c mortality from metaanalyses
of large prospective studies. We calculated the population attributable fractions for- each risk factor alone,
and for the combination of all risk factors, accounting for multicausality and for mediation of the eff ects of BMI by the other three risks. We calculated attributable deaths by multiplying the cause-specifi c population attributable fractions by the number of disease-specifi c deaths. We obtained cause-specifi c mortality from the Global Burden of Diseases, Injuries, and Risk Factors 2010 Study. We propagated the uncertainties of all the inputs to the fi nal estimates.
Findings In 2010, high blood pressure was the leading risk factor for deaths due to cardiovascular diseases, chronic kidney disease, and diabetes in every region, causing more than 40% of worldwide deaths from these diseases; high BMI and glucose were each responsible for about 15% of deaths, and high cholesterol for more than 10%. After
accounting for multicausality, 63% (10\ub78 million deaths, 95% CI 10\ub71\u201311\ub75) of deaths from these diseases in 2010 were attributable to the combined eff ect of these four metabolic risk factors, compared with 67% (7\ub71 million deaths,
6\ub76\u20137\ub76) in 1980. The mortality burden of high BMI and glucose nearly doubled from 1980 to 2010. At the country
level, age-standardised death rates from these diseases attributable to the combined eff ects of these four risk factors
surpassed 925 deaths per 100 000 for men in Belarus, Kazakhstan, and Mongolia, but were less than 130 deaths per 100 000 for women and less than 200 for men in some high-income countries including Australia, Canada, France,
Japan, the Netherlands, Singapore, South Korea, and Spain.
Interpretation The salient features of the cardiometabolic disease and risk factor epidemic at the beginning of
the 21st century are high blood pressure and an increasing eff ect of obesity and diabetes. The mortality burden
of cardiometabolic risk factors has shifted from high-income to low-income and middle-income countries. Lowering
cardiometabolic risks through dietary, behavioural, and pharmacological interventions should be a part of the globalresponse to non-communicable diseases
A descriptive analysis of medical health services utilization of Veterans living in Ontario: a retrospective cohort study using administrative healthcare data
- …
