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Search Results: 1 - 10 of 3703 matches for " Joshua Belanich "
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On the Convergence Properties of Optimal AdaBoost
Joshua Belanich,Luis E. Ortiz
Computer Science , 2012,
Abstract: AdaBoost is one of the most popular machine-learning algorithms. It is simple to implement and often found very effective by practitioners, while still being mathematically elegant and theoretically sound. AdaBoost's behavior in practice, and in particular the test-error behavior, has puzzled many eminent researchers for over a decade: It seems to defy our general intuition in machine learning regarding the fundamental trade-off between model complexity and generalization performance. In this paper, we establish the convergence of "Optimal AdaBoost," a term coined by Rudin, Daubechies, and Schapire in 2004. We prove the convergence, with the number of rounds, of the classifier itself, its generalization error, and its resulting margins for fixed data sets, under certain reasonable conditions. More generally, we prove that the time/per-round average of almost any function of the example weights converges. Our approach is to frame AdaBoost as a dynamical system, to provide sufficient conditions for the existence of an invariant measure, and to employ tools from ergodic theory. Unlike previous work, we do not assume AdaBoost cycles; actually, we present empirical evidence against it on real-world datasets. Our main theoretical results hold under a weaker condition. We show sufficient empirical evidence that Optimal AdaBoost always met the condition on every real-world dataset we tried. Our results formally ground future convergence-rate analyses, and may even provide opportunities for slight algorithmic modifications to optimize the generalization ability of AdaBoost classifiers, thus reducing a practitioner's burden of deciding how long to run the algorithm.
Some Open Problems in Optimal AdaBoost and Decision Stumps
Joshua Belanich,Luis E. Ortiz
Computer Science , 2015,
Abstract: The significance of the study of the theoretical and practical properties of AdaBoost is unquestionable, given its simplicity, wide practical use, and effectiveness on real-world datasets. Here we present a few open problems regarding the behavior of "Optimal AdaBoost," a term coined by Rudin, Daubechies, and Schapire in 2004 to label the simple version of the standard AdaBoost algorithm in which the weak learner that AdaBoost uses always outputs the weak classifier with lowest weighted error among the respective hypothesis class of weak classifiers implicit in the weak learner. We concentrate on the standard, "vanilla" version of Optimal AdaBoost for binary classification that results from using an exponential-loss upper bound on the misclassification training error. We present two types of open problems. One deals with general weak hypotheses. The other deals with the particular case of decision stumps, as often and commonly used in practice. Answers to the open problems can have immediate significant impact to (1) cementing previously established results on asymptotic convergence properties of Optimal AdaBoost, for finite datasets, which in turn can be the start to any convergence-rate analysis; (2) understanding the weak-hypotheses class of effective decision stumps generated from data, which we have empirically observed to be significantly smaller than the typically obtained class, as well as the effect on the weak learner's running time and previously established improved bounds on the generalization performance of Optimal AdaBoost classifiers; and (3) shedding some light on the "self control" that AdaBoost tends to exhibit in practice.
Do Ghanaians Prefer Imported Textiles to Locally Manufactured Ones?  [PDF]
Peter Quartey, Joshua Abor
Modern Economy (ME) , 2011, DOI: 10.4236/me.2011.21009
Abstract: This paper ascertains whether consumers prefer locally made textile to imported ones or vice versa and what accounts for the choice. The study uses survey data of industry, traders and consumers to explain the issue. The results show that most consumers prefer locally-made textiles to imported ones. More than half of those who prefer locally-made textiles claimed local textile products are of a better quality. Others claimed they are more affordable and attractive while a few claimed local textiles are cheaper. This appears to contradict the country-of-origin effect and the results of previous studies in Africa and other developing countries. Im-plications for traders, governments and local manufacturers are also discussed. The study provides insights with respect to Ghanaians’ preference of locally-produced textiles to foreign-made ones.
Providing Sustainable Supports for Street Children in Nigeria:Stakeholders Challenges and the Policy Options Available  [PDF]
Joshua Oyeniyi Aransiola
Advances in Applied Sociology (AASoci) , 2013, DOI: 10.4236/aasoci.2013.33023

This article examines the limitations of all stakeholders in providing support for street children in Nigeria in the face of continuous increase in their number with a view to identify possible policy options in the light of inabilities of the stakeholders to adequately support the children. Qualitative research techniques were employed to collect the primary data from NGOs, community members and government agencies saddled with the responsibility of caring for the children. It was found that the stakeholders are incapable of addressing the problems of street children due to inadequate skills, lack of necessary facilities and stakeholders working in parallels among others. It emphasizes the need for collaboration among stakeholders to enjoy the benefit of synergy while there is also need to embark on capacity development for all the stakeholders in order to make meaningful progress and the situation of the street children improved in the country.

A Reconfigurable Network-on-Chip Datapath for Application Specific Computing  [PDF]
Joshua Weber, Erdal Oruklu
Circuits and Systems (CS) , 2013, DOI: 10.4236/cs.2013.42025

This paper introduces a new datapath architecture for reconfigurable processors. The proposed datapath is based on Network-on-Chip approach and facilitates tight coupling of all functional units. Reconfigurable functional elements can be dynamically allocated for application specific optimizations, enabling polymorphic computing. Using a modified network simulator, performance of several NoC topologies and parameters are investigated with standard benchmark programs, including fine grain and coarse grain computations. Simulation results highlight the flexibility and scalability of the proposed polymorphic NoC processor for a wide range of application domains.

Refining Use/Misuse/Mitigation Use Cases for Security Requirements  [PDF]
Joshua J. Pauli
Journal of Software Engineering and Applications (JSEA) , 2014, DOI: 10.4236/jsea.2014.78058

We investigate security at the same time as the functional requirements by refining and integrating use, misuse, and mitigation use cases. Security requirements rely on the interactions among normal system execution (use cases), attacks (misuse cases), and necessary security strategies (mitigation use cases), but previous approaches only use a high-level of abstraction. We use refinement to uncover details of each case and the relationships among them before integrating them. We identify and model “includes” and “extends” relationships within each refined case type, and use a condition-driven process that maintains these relationships as refinement continues. We then systematically identify and model “threatens” and “mitigates” relationships to integrate the cases at a detailed level.

Establishing a Different Dimension of Citizen Security: The Case for Special Protection for Whistleblowers  [PDF]
David Lewis, Joshua Castellino
Beijing Law Review (BLR) , 2013, DOI: 10.4236/blr.2013.44024

The notion of citizens’ security has usually been viewed primarily as a binary relationship between the State and the citizen in a Rousseauesque interpretation. This article argues for a broader conception of citizens’ security focussing on the right to “blow the whistle” in an employment context. We believe that with the growing importance of global business in society it is imperative that special measures are designed for this important class of citizens. A failure to do so, in our opinion, is likely to harm the maintenance of effective protection, especially in developing countries, to the detriment of citizens’ security.

Perceptions and Use of Herbal Remedies among Patients with Diabetes Mellitus in Murang’a North District, Kenya  [PDF]
Joshua Mwangi, Lucy Gitonga
Open Journal of Clinical Diagnostics (OJCD) , 2014, DOI: 10.4236/ojcd.2014.43024
Abstract: Diabetes mellitus is a chronic disease with a world wide distribution. Use of herbal remedies has been on increase with World Health Organization estimating that 80 percent of the world’s population presently uses some form of herbal medicine for some aspect of primary health care. Objectives of this study were therefore to determine the perceptions people with diabetes mellitus have towards herbal remedies, to determine the extent to which they use herbal remedies and also to establish whether there is any association between the perceptions people have on herbal remedies and use of herbal remedies. The study was carried out in Murang’a District, in Mathioya and Kangema Constituencies where five community health units were purposively selected to participate in the study based on their level of establishment in community health strategy. Data was collected using interview schedules. SPSS was used for data analysis. Significant findings from this study were: a significant number of the respondents (15%) were diagnosed with diabetes mellitus when already admitted in the wards prior to which period they had no idea that they were diabetic, over 86% of those interviewed were given information on diabetes management on diagnosis and they attend hospital clinics for follow-up regularly and therefore this means that the reason for seeking alternative modes of treatment is not due to lack of information on diabetes but due to other reasons, 12.4% of those interviewed admitted using herbal remedies as part of their management of diabetes. Recommendations made following the study were: the government of Kenya through Ministry of Health should encourage rigorous screening of clients and population in general for diabetes to ensure diabetes is diagnosed early and put under appropriate management and that the government of Kenya through Ministry of Health should put up a campaign educating diabetic patients on the potential dangers associated with combining herbal remedies with contemporary medicines due to their interactions.
Quantifying the Value of Open Source Hard-ware Development  [PDF]
Joshua M. Pearce
Modern Economy (ME) , 2015, DOI: 10.4236/me.2015.61001
Abstract: With the maturation of digital manufacturing technologies like 3-D printing, a new paradigm is emerging of distributed manufacturing in both scientific equipment and consumer goods. Hardware released under free licenses is known as free and open source hardware (FOSH). The availability of these FOSH designs has a large value to those with access to digital manufacturing methods and particularly for scientists with needs for highly-customized low-volume production products. It is challenging to use traditional funding models to support the necessary investment of resources in FOSH development because of the difficulty in quantifying the value of the result. In order to overcome that challenge and harvest the current opportunity in both low-cost scientific equipment and consumer products, this article evaluates the following methods to quantify the value of FOSH design including: 1) downloaded substitution valuation; 2) avoided reproduction valuation and 3) market savings valuation along with additional benefits related to market expansion, scientific innovation acceleration, educational enhancement and medical care improvement. The strengths and weaknesses of these methods are analyzed and the results show that the methods are relatively straight-forward to institute, based on reliable freely-available data, and that they minimize assumptions. A case study of a syringe pump with numerous scientific and medical applications is presented. The results found millions of dollars of economic value from a relatively simple scientific device being released under open-licenses representing orders of magnitude increase in value from conventional proprietary development. The inescapable conclusion of this study is that FOSH development should be funded by organizations interested in maximizing return on public investments particularly in technologies associated with science, medicine and education.
The Effect of Lion’s Ear (Leonotis nepetifolia) and African Basil (Ocimum gratissimum) Plant Extracts on Two-Spotted Spider Mites (Tetranychus urticae) for Improved Yield and Quality of French Beans  [PDF]
Kennedy Ogayo, Jane Nyaanga, Joshua Ogweno, Joshua Ogendo
Advances in Entomology (AE) , 2019, DOI: 10.4236/ae.2019.71003
Abstract: An experiment to evaluate the bio-control potential of Leonotis nepetifolia and Ocimum gratissimum plant extracts against two-spotted spider mites on French beans was conducted in the field. Five plant extract concentrations (1.5%, 3.0%, 6.0% and 12.0% w/v) were applied with water and Abamectin 0.6 ml/L as controls. Mite counts were done before and after treatment application and expressed as corrected percent efficacy. The impact of the mites on the French beans was evaluated by recording percent leaf reduction and quality and quantity by number of pods, pod length, diameter and yield. There was a dose dependent response in percent mite and leaf reduction, number of pods and yield. Treatments applied at 12% w/v indicated higher mite reduction (82.75%) for L. nepetifolia and 69.06% for O. gratissimum compared to abamectin (65.76%). The lowest percent leaf reduction of 1.71% for L. nepetifolia 0.39% for O. gratissimum and abamectin (20.46%) was also at 12% w/v. Similarly, the highest number of pod (61.00) for L. nepetifolia, 48.67 for O. gratissimum compared to 28.33 abamectin and yield (0.88 kg) for L. nepetifolia and 0.90 kg for O. gratissimum was also recorded at 12% w/v compared to 0.36 kg for abamectin. There were no significant differences in pod diameter and pod length between the extracts concentrations and abamectin. The study demonstrated the efficacy of L. nepetifolia and O. gratissimum in managing two-spotted spider mite and subsequent increase in French bean yield under field conditions.
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