ACCOUNTING FOR MONOTONE ATTRITION IN A POSTPARTUM DEPRESSION CLINICAL TRIAL

Longitudinal studies in public health, medicine and the social sciences are often complicated by monotone attrition, where a participant drops out before the end of the study and all his/her subsequent measurements are missing. To obtain accurate non-biased results, it is of public health importance to utilize appropriate missing data analytic methods to address the issue of monotone attrition.The defining feature of longitudinal studies is that several measurements are taken for each participant over time. The commonly used methods to analyze incomplete longitudinal data, complete case analysis and last observation carried forward, are not recommended because they produce biased estimators. Simple imputation and multiple imputation procedures provide alternative approaches for addressing monotone attrition. However, simple imputation is difficult in a multivariate setting and produces biased estimators. Multiple imputation addresses those shortcomings and allows a straightforward assessment of the sensitivity of inferences to various models for non-response. This thesis reviews the literature on missing data mechanisms and missing data analysis methods for monotone attrition. Data from a postpartum depression clinical trial comparing the effects of two drugs (Nortriptyline and Sertraline) on remission status at 8 weeks were re-analyzed using these methods. The original analysis, which only used available data, was replicated first. Then patterns and predictors of attrition were identified. Last observation carried forward, mean imputation and multiple imputation were used to account for both monotone attrition and a small number of intermittent missing measurements. In multiple imputation, every missing measurement was imputed 6 times by predictive matching. Each of the 6 completed data sets was analyzed separately and the results of all the analyses were combined to get the overall estimate and standard errors. In each analysis, continuous remission levels were imputed but the probability of remission was analyzed. The original conclusion of no significant difference in probability of remission at week 8 between the two drug groups was sustained even after carrying the missing measurements forward, mean and multiple imputations. Most drop outs occurred during the first three weeks and participants taking Sertraline who live alone were more likely to drop out

Exploring ERP-enabled Technology Adoption: A Real Options Perspective

For decades, practitioners and scholars have focused on achieving optimal values in and benefits from enterprise resource planning (ERP) systems. Given that scholars have identified ERP systems as having option-like characteristics such as the capacity to create an information technology (IT) platform that enables the adoption of subsequent function-specific applications, we face a need to explore the linkage between post-ERP systems implementation and subsequent ERP-enabled technology adoption. We used real options theory to explore the underlying relationship between the initial ERP system implementation and subsequent technology adoptions. We surveyed 519 IT executives in the United States and found that the level of technology uncertainty, managerial flexibility, and formal real option analysis in ERP adoption decisions influenced the organizational relative advantage of subsequent non-ERP technologies. Our results also reveal that the level of uncertainty had a negative relationship with ERP-enabled technology adoption, while formal real option analysis in ERP adoption decisions positively influenced ERP-enabled adoption

Fast molecular methods for the detection of spoilage fungi (in food products)

In the present thesis, the detection of spoilage and mycotoxigenic fungi in different food matrices was achieved in 24-48 h, providing a faster alternative to the conventional culture-based techniques which require up to 7 days from sampling to result. Consequently, the developed methods present an interesting alternative for the food industry resulting in reduction of costs associated with lengthy analyses and product recalls. Small modifications of the proposed methodology including enrichment time and temperature as well as sample size have proven to contribute to higher sensitivity and/or specificity which gives the developed methodology the required flexibility to fit the needs of the food industry. Furthermore, the different methods showcased different advantages. In particular, the real-time PCR assays have proven to be more sensitive; however, they require a real-time thermocycler in order to be performed. On the other hand, the isothermal amplification techniques coupled with naked-eye detection could be used for POC testing and early screening since they only require a heating device; providing in many cases a comparable sensitivity to the qPCR assays

Examining Exploitability Risk of Vulnerabilities: A Hazard Model

With the increasing number and severity of security incidents and exploits, information technology (IT) vendors, security managers, and consumers have begun to place more emphasis on security. Yet, fixing the sheer volume of vulnerabilities remains a challenge as IT vendors race against attackers to evaluate system vulnerabilities, prioritize them, and issue security patches before cybercriminals can exploit them. In this study, we posit that IT vendors can prioritize which vulnerabilities they should patch first by assessing their exploitability risk. Accordingly, we identified the vulnerabilities that cybercriminals will most likely exploit using vulnerability-related attributes and vulnerability types. To do so, we employed survival analysis and tested our models using historical data of vulnerabilities and exploits between 2007 and 2016. Our results indicate that IT vendors benefit the most from fixing remotely exploitable vulnerabilities; non-complex vulnerabilities; vulnerabilities that require no authentication; and vulnerabilities that affect confidentiality, integrity, and availability components. Furthermore, our findings suggest that IT vendors can mitigate the risk of exploit-related attacks by remedying code-injection vulnerabilities, buffer-overflow vulnerabilities, and numeric-error vulnerabilities

The Contributions of the Army to National Integration in Israel: The Case of Oriental Jews.

It is the purpose of this study to establish how the Army in Israel contributes to the National Integration of Jews who originated in the Middle East and in North Africa and who arrived in Israel en masse after the foundation of the State. To assess this contribution, three steps are followed: 1) The establishment of a methodology as an analytical tool to determine what is meant in Israel by National Integration and the nature of the political formula. 2) The description of three main branches of the Army apparatus, together with their activities, 3) The activities of the Army are evaluated in terms of the political formula in order to determine the direction and success of its contribution to the process of National Integration. The findings of this study show that no soldier is allowed to leave the Army without proficiency and literacy in the Hebrew language, elementary education and some form of vocational training. The IDF ensures that the discharged soldier can earn his living and become a useful member of the society. Recruits are made aware not only of their rights in a democratic society, but also of their obligations towards that society. A strong identification with the land together with knowledge of the land and its history are imparted to all soldiers, both academically and empirically. On the other hand, the IDF's contribution in the areas of education and economic specialization have not been sufficient to integrate Orientals with Ashkenazim, The progress of National Integration has been hindered by the exclusion from the Army of "uneducated" women, the majority of whom are Oriental; by the Army's lack of contribution to ecological dispersion, and by its lack of receptivity to the Oriental's culture and beliefs

Binocular rivalry alternations and their relation to visual adaptation

When different stimuli are presented dichoptically, perception alternates between the two in a stochastic manner. After a long-lasting and rigorous debate, there is growing consensus that this phenomenon, known as binocular rivalry (BR), is the result of a dynamic competition occurring at multiple levels of the visual hierarchy. The role of low- and high-level adaptation mechanisms in controlling these perceptual alternations has been a key issue in the rivalry literature. Both types of adaptation are dispersed throughout the visual system and have an equally influential, or even causal, role in determining perception. Such an explanation of BR is also in accordance with the relationship between the latter and attention. However, an overall explanation of this intriguing perceptual phenomenon needs to also include noise as an equally fundamental process involved in the stochastic resonance of perceptual bistability

IT Capability and Digital Transformation: A Firm Performance Perspective

As emerging digital technologies and capabilities continue to dominate our economic landscape, organizations are facing increased scrutiny on how digital transformation can provide the mechanism for innovation and firm performance. Using resource-based view (RBV) framework, this research examines the mediating effects of digital transformation in the relationship between IT capability and firm performance. Empirical data collected from CIOs from US firms reveal that although IT capability positively influences firm performance, it is mediated by digital transformation. Furthermore, our findings show that digital transformation positively influences innovation and firm performance while innovation is reaffirmed as having a positive implication on firm performance

The Influence of Organizational Trust and Organizational Mindfulness on ERP Systems Usage

This paper examines how organizational trust and organizational mindfulness shape enterprise resource planning (ERP) system usage. We focus on five dimensions of trust: competence, openness and honesty, concern for employees, reliability, and identification. Drawing on organizational trust and organizational mindfulness theories, we argue that perception of organizational trust among ERP users might explain ERP system usage. We also predict that organizational mindfulness among ERP users positively influences ERP system usage. Our study draws on a total of 231 questionnaires collected from ERP system users across the United States. The results suggest that organizational trust dimensions (namely, competence, concern for employees, and identification) affect ERP system usage. Consistent with the theory, the results also support the idea that organizational trust (i.e., competence, openness and honesty, concern for employees, and identification) create supportive infrastructure-enabling organizational mindfulness. Finally, the study shows key antecedents of organizational mindfulness and underscores the importance of organizational mindfulness as a way of encouraging ERP system usage

Modeling Patient Flow in a Network of Intensive Care Units (ICUs)

Beginning in 2012, the Department of Health and Human Services (HHS) started adjusting payment for specific conditions by 30% for hospitals with 30-day patient readmission rates higher than the 75th percentile (HHS.gov, 2011). Furthermore, starting in 2013, HHS requires hospitals to publish their readmission rates (HHS.gov, 2011). It is also estimated that by 2013, healthcare expenditures in the United States will account for 18.7% of the Gross Domestic Product (GDP) (Centers of Medicare and Medicaid Services and US Bureau of Census, 2004). Yet the US healthcare system still suffers from congestion and rising costs as illustrated by hospital congestion. One way to reduce congestion and improve patient flow in the hospital is by modeling patient flow. Using queueing theory, we determined the steady state solution of an open queueing network, while accounting for instantaneous and delayed feedback. We also built a discrete event simulation model of patient flow in a network of Intensive Care Units (ICUs), while considering instantaneous and delayed readmissions, and validated the model using real patient flow data that was collected over four years. In addition, we compared several statistical and data mining techniques in terms of classifying patient status at discharge from the ICU (highly imbalanced data) and identify methods that perform the best. Our work has several contributions. Modeling patient flow while accounting for instantaneous and delayed feedback is considered a major contribution, as we are unaware of any patient flow study that has done so. Validating the discrete event simulation model allows for the implementation and application of the model in the real world by unit managers and administrators. The simulation model could be used to test different scenarios of patient flow, and to identify optimal resource allocation strategies in terms of number of beds and/or staff schedules in order to maximize patient throughput, reduce patient wait time and improve patients’ outcome. Moreover, identifying high risk patients who are more likely to die in the ICU ensures that those patients are receiving appropriate and timely care, so their risk of death is reduced

Population dynamics of date moth adults in date palm groves in Sidi Okbabiskra; (Sahara – Algeria)

The date moth Ectomyelois ceratoniae (Zeller) (Lepidoptera: Pyralidae)  can cause total production losses and is considered a key pest of date  palm in Algeria. This research aimed to evaluate the adult dynamic of E. ceratoniae in date palm grove throughout one year (2016). Two high flight periods were recorded in the spring and autumn. The first adult emergence was in 6th of Feburary 2016. Also, results showed that climatic factors have a significant influence on the date moth which could only develop over a limited range of temperatures and relative humidity.Keywords: Ectomyelois ceratoniae; Population dynamics; Phoenix dactylifera; sexual pheromone traps; climatic parameters