bluuebunny/crossref_metadata_2025_split huggingface dataset:
MissForest—non-parametric missing value imputation for mixed-type data
Authors: Stekhoven Daniel J. , Bühlmann Peter 
Published: October 2011

Abstract
Motivation: Modern data acquisition based on high-throughput technology is often facing the problem of missing data. Algorithms commonly used in the analysis of such large-scale data often depend on a complete set. Missing value imputation offers a solution to this problem. However, the majority of available imputation methods are restricted to one type of variable only: continuous or categorical. For mixed-type data, the different types are usually handled separately. Therefore, these methods ignore possible relations between variable types. We propose a non-parametric method which can cope with different types of variables simultaneously.
Results: We compare several state of the art methods for the imputation of missing values. We propose and evaluate an iterative imputation method (missForest) based on a random forest. By averaging over many unpruned classification or regression trees, random forest intrinsically constitutes a multiple imputation scheme. Using the built-in out-of-bag error estimates of random forest, we are able to estimate the imputation error without the need of a test set. Evaluation is performed on multiple datasets coming from a diverse selection of biological fields with artificially introduced missing values ranging from 10% to 30%. We show that missForest can successfully handle missing values, particularly in datasets including different types of variables. In our comparative study, missForest outperforms other methods of imputation especially in data settings where complex interactions and non-linear relations are suspected. The out-of-bag imputation error estimates of missForest prove to be adequate in all settings. Additionally, missForest exhibits attractive computational efficiency and can cope with high-dimensional data.
Availability: The ℝ package missForest is freely available from http://stat.ethz.ch/CRAN/.
Contact: stekhoven@stat.math.ethz.ch; buhlmann@stat.math.ethz.ch
Link between decisions regarding resuscitation and preferences for quality over length of life with heart failure
Authors: Dev Sandesh , Clare Robert M. , Felker G. Michael , Fiuzat Mona , Stevenson Lynne Warner , O'Connor Christopher M. 
Published: October 2011

AimsSurvival preferences, ascertained from time‐trade‐off utilities, have not been studied in heart failure patients who designate a ‘do not resuscitate’ (DNR) status. Therefore, the aim of this study was to determine the association of heart failure patients' resuscitation preferences with survival preferences and mortality in the ESCAPE trial.Methods and resultsWe analysed the association of resuscitation orders at 1 month with time‐trade‐off utilities and 6‐month mortality. There were 26 and 349 patients with a DNR order and Full Code order, respectively. DNR patients were older, had more coronary artery disease, hypertension, renal impairment, and poorer exercise capacity than Full Code patients. DNR patients also experienced longer hospitalization and higher 6‐month mortality. In multivariate analysis, DNR preference was associated with 10‐fold higher odds of willingness to trade survival time (lower time‐trade‐off utility) in favour of improved quality of life [odds ratio 10.33, 95% confidence interval (CI) 1.65–64.80]. DNR preference was the best predictor of mortality (χ2 26.12, P < 0.0001, hazard ratio 6.88, 95% CI 3.28–14.41), despite adjustment for known predictors including brain natriuretic peptide.ConclusionsHeart failure patients' requests to forgo resuscitation may signify more than simply ‘what‐if’ directives for emergency care. DNR decisions may reflect preferences for intervention to enhance quality rather than prolong survival, which is particularly important as these patients have high early mortality.
Mapping, Complementation, and Targets of the Cysteine Protease Actinidin in Kiwifruit
Authors: Nieuwenhuizen Niels J. , Maddumage Ratnasiri , Tsang Gianna K. , Fraser Lena G. , Cooney Janine M. , De Silva H. Nihal , Green Sol , Richardson Kim A. , Atkinson Ross G. 
Published: October 2011

AbstractCysteine proteases (CPs) accumulate to high concentration in many fruit, where they are believed to play a role in fungal and insect defense. The fruit of Actinidia species (kiwifruit) exhibit a range of CP activities (e.g. the Actinidia chinensis variety YellowA shows less than 2% of the activity of Actinidia deliciosa variety Hayward). A major quantitative trait locus for CP activity was mapped to linkage group 16 in a segregating population of A. chinensis. This quantitative trait locus colocated with the gene encoding actinidin, the major acidic CP in ripe Hayward fruit encoded by the ACT1A-1 allele. Sequence analysis indicated that the ACT1A locus in the segregating A. chinensis population contained one functional allele (A-2) and three nonfunctional alleles (a-3, a-4, and a-5) each containing a unique frameshift mutation. YellowA kiwifruit contained two further alleles: a-6, which was nonfunctional because of a large insertion, and a-7, which produced an inactive enzyme. Site-directed mutagenesis of the act1a-7 protein revealed a residue that restored CP activity. Expression of the functional ACT1A-1 cDNA in transgenic plants complemented the natural YellowA mutations and partially restored CP activity in fruit. Two consequences of the increase in CP activity were enhanced degradation of gelatin-based jellies in vitro and an increase in the processing of a class IV chitinase in planta. These results provide new insight into key residues required for CP activity and the in vivo protein targets of actinidin.
Shoot Branching and Leaf Dissection in Tomato Are Regulated by Homologous Gene Modules
Authors: Busch Bernhard L. , Schmitz Gregor , Rossmann Susanne , Piron Florence , Ding Jia , Bendahmane Abdelhafid , Theres Klaus 
Published: October 2011

AbstractAerial plant architecture is predominantly determined by shoot branching and leaf morphology, which are governed by apparently unrelated developmental processes, axillary meristem formation, and leaf dissection. Here, we show that in tomato (Solanum lycopersicum), these processes share essential functions in boundary establishment. Potato leaf (C), a key regulator of leaf dissection, was identified to be the closest paralog of the shoot branching regulator Blind (Bl). Comparative genomics revealed that these two R2R3 MYB genes are orthologs of the Arabidopsis thaliana branching regulator REGULATOR OF AXILLARY MERISTEMS1 (RAX1). Expression studies and complementation analyses indicate that these genes have undergone sub- or neofunctionalization due to promoter differentiation. C acts in a pathway independent of other identified leaf dissection regulators. Furthermore, the known leaf complexity regulator Goblet (Gob) is crucial for axillary meristem initiation and acts in parallel to C and Bl. Finally, RNA in situ hybridization revealed that the branching regulator Lateral suppressor (Ls) is also expressed in leaves. All four boundary genes, C, Bl, Gob, and Ls, may act by suppressing growth, as indicated by gain-of-function plants. Thus, leaf architecture and shoot architecture rely on a conserved mechanism of boundary formation preceding the initiation of leaflets and axillary meristems.
Model predictive control for autonomous unmanned helicopters
Authors: Joelianto Endra , Maryami Sumarjono Edwina , Budiyono Agus , Retnaning Penggalih Dini 
Published: October 2011

PurposeThe purpose of this paper is to investigate the feasibility of controlling a small‐scale helicopter by using the model predictive control (MPC) method.Design/methodology/approachThe MPC control synthesis is employed by considering five linear models representing the flight of a small‐scale helicopter from hover to high‐speed cruise. The internal model principle is employed for the trajectory tracking design.FindingsIt is found that the MPC handles well the transition problems between the models, yields satisfactory tracking control performance and produces a suitable control signal. The performance of the tracking control of the helicopter is considerably influenced by the parameter selection in the states and inputs weighting matrices of the MPC. Simulation results also showed that faster dynamics, coupling problems, input and output constraints and changing linearized multi‐inputs multi‐outputs dynamics models in the small‐scale helicopter can be handled simultaneously by the MPC controller.Research limitations/implicationsThe present study is limited for the application of MPC for the control of small‐scale helicopters with non‐aggressive maneuvers.Practical implicationsThe result can be extended to design a full envelope controller for an autonomous small‐scale helicopter without the need to resort to a conventional gain scheduling technique.Originality/valueHelicopter control system designs using MPC with a single either linear or non‐linear model have been studied and reported in numerous literatures. The main contribution of the paper is in the application of MPC to handle the control problems of a small‐scale helicopter defined as a mathematical model with several different modes during a flight mission.
Reactive collision avoidance of multiple realistic UAVs
Authors: Manathara Joel George , Ghose Debasish 
Published: October 2011

PurposeUnmanned aerial vehicles (UAVs) have a wide variety of applications such as surveillance and search. Many of these tasks are better executed by multiple UAVs acting as a group. One of the main problems to be tackled in a high‐density UAV traffic scenario is that of collision avoidance among UAVs. The purpose of this paper is to give a collision avoidance algorithm to detect and resolve the conflicts of projected path among UAVs.Design/methodology/approachThe collision avoidance algorithm developed in the paper handles multiple UAV conflicts by considering only the most imminent predicted collision and doing a maneuver to increase the line‐of‐sight rate to avoid that conflict. After the collision avoidance maneuver, the UAVs fly to their destinations via Dubins shortest path to minimize time to reach destination. The algorithm is tested on realistic six degree of freedom UAV models augmented with proportional‐integral controllers to hold altitude, velocity, and commanded bank angles.FindingsThe paper shows, through extensive simulations, that the proposed collision avoidance algorithm gives a good performance in high‐density UAV traffic scenarios. The proposed collision avoidance algorithm is simple to implement and is computationally efficient.Practical implicationsThe algorithm developed in this paper can be easily implemented on actual UAVs.Originality/valueThere are only a few works in the literature that address multiple UAV collision avoidance in very high‐density traffic situations. This paper addresses very high‐density multiple UAV conflict resolution with realistic UAV models.
Obstacle avoidance for small UAVs using monocular vision
Authors: Lee Jeong‐Oog , Lee Keun‐Hwan , Park Sang‐Heon , Im Sung‐Gyu , Park Jungkeun 
Published: October 2011

PurposeThe purpose of this paper is to propose that the three‐dimensional information of obstacles should be identified to allow unmanned aerial vehicles (UAVs) to detect and avoid obstacles existing in their flight path.Design/methodology/approachFirst, the approximate outline of obstacles was detected using multi‐scale‐oriented patches (MOPS). At the same time, the spatial coordinates of feature points that exist in the internal outline of the obstacles were calculated through the scale‐invariant feature transform (SIFT) algorithm. Finally, the results from MOPS and the results from the SIFT algorithm were merged to show the three‐dimensional information of the obstacles.FindingsAs the method proposed in this paper reconstructs only the approximate outline of obstacles, a quick calculation can be done. Moreover, as the outline information is combined through SIFT feature points, detailed three‐dimensional information pertaining to the obstacles can be obtained.Practical implicationsThe proposed approach can be used efficiently in GPS‐denied environments such as certain indoor environments.Originality/valueFor the autonomous flight of small UAVs having a payload limit, this paper suggests a means of forming three‐dimensional information about obstacles with images obtained from a monocular camera.
Hardware‐in‐the‐loop simulation for visual target tracking of octorotor UAV
Authors: Rilanto Trilaksono Bambang , Triadhitama Ryan , Adiprawita Widyawardana , Wibowo Artiko , Sreenatha Anavatti 
Published: October 2011

PurposeThe purpose of this paper is to present the development of hardware‐in‐the‐loop simulation (HILS) for visual target tracking of an octorotor unmanned aerial vehicle (UAV) with onboard computer vision.Design/methodology/approachHILS for visual target tracking of an octorotor UAV is developed by integrating real embedded computer vision hardware and camera to software simulation of the UAV dynamics, flight control and navigation systems run on Simulink. Visualization of the visual target tracking is developed using FlightGear. The computer vision system is used to recognize and track a moving target using feature correlation between captured scene images and object images stored in the database. Features of the captured images are extracted using speed‐up robust feature (SURF) algorithm, and subsequently matched with features extracted from object image using fast library for approximate nearest neighbor (FLANN) algorithm. Kalman filter is applied to predict the position of the moving target on image plane. The integrated HILS environment is developed to allow real‐time testing and evaluation of onboard embedded computer vision for UAV's visual target tracking.FindingsUtilization of HILS is found to be useful in evaluating functionality and performance of the real machine vision software and hardware prior to its operation in a flight test. Integrating computer vision with UAV enables the construction of an unmanned system with the capability of tracking a moving object.Practical implicationsHILS for visual target tracking of UAV described in this paper could be applied in practice to minimize trial and error in various parameters tuning of the machine vision algorithm as well as of the autopilot and navigation system. It also could reduce development costs, in addition to reducing the risk of crashing the UAV in a flight test.Originality/valueA HILS integrated environment for octorotor UAV's visual target tracking for real‐time testing and evaluation of onboard computer vision is proposed. Another contribution involves implementation of SURF, FLANN, and Kalman filter algorithms on an onboard embedded PC and its integration with navigation and flight control systems which enables the UAV to track a moving object.
Configuration design and optimisation study of a compound gyroplane
Authors: Anh Vu Ngoc , Lee Young‐Jae , Lee Jae‐Woo , Kim Sangho , Jae Chung In 
Published: October 2011

PurposeThe purpose of this paper is to study the conceptual design and optimisation of a compound gyroplane. A study of a compound gyroplane configuration and its characteristics was performed to develop a sizing program.Design/methodology/approachThe vertical takeoff and landing capabilities of a helicopter are particularly important. The need for efficient hover and the effectiveness of forward flight in the helicopter can cause conflicts within the design process. The designers usually wish to increase the helicopter's maximum forward speed. Recently, the compound aircraft is one of the concepts considered for the purpose of expanding the flight envelope of rotorcraft. The study of the compound gyroplane showed its advance capabilities for this purpose. Understanding its characteristics, a number of calculations are conducted to implement a sizing program for compound gyroplanes based on the conventional helicopter sizing process.FindingsThe results of the sizing program were validated using existing aircraft data such as the Challis Heliplane, Carter Copter, FB‐1 Gyrodyne, and Jet Gyrodyne. The program is appropriate to size a compound gyroplane at the conceptual design phase. An optimisation study was also performed to enhance sizing results. The compromise between the rotor lift sharing factor and the ratio of the wing span (Bw) to rotor diameter (D) was solved by choosing the total gross weight (TOGW) as the objective function, while the design variables are compromising factors. The optimum results showed that the TOGW of all four kinds of compound gyroplanes was considerably reduced.Originality/valueA conceptual sizing program for unconventional compound aircraft was developed. The study showed that an optimum design process is necessary to enhance the sizing results.
Functionality of pizza ingredients
Authors: Singh Preeti , Goyal G.K. 
Published: October 2011

PurposeThis paper aims to review the types of pizza and the functionality of basic ingredients of pizza with special focus on the effects of pizza toppings on health.Design/methodology/approachPhenomenological research has raised awareness and increased insight into the role of various pizza ingredients and health benefits of different pizza toppings and consequently pizza is called a “functional food”. The approach is based on observation of the online research, a close watch on the pizza industry, analysis of research papers in journals, and brainstorming research on the effect of packaging on the quality of different pizza ingredients with a co‐researcher for four years.FindingsThe changing life patterns and food habits of people and their preferences have catapulted the market to grow for convenience and fast foods. Pizza is one of the most popular family foods worldwide and has gained widespread consumer acceptance as a healthy and convenience food. It is a multi‐component product with composite number of toppings. It provides an array of nutrients in significant amounts, in relation to its energy and fat content, making it a nutrient‐dense food. It is cheap and can be delivered in a very short time. In particular, pizza supplies 30 per cent of the USA recommended daily allowance of vitamins A, C, B2, calcium and protein. It contains 50 per cent of vitamin B1 and 35 per cent of iron. Furthermore, pizza has anticancerous effects beyond the basic nutrition it provides, because of the potent antioxidant lycopene present in tomatoes.Originality/valueThis paper offers a holistic view that would guide a reader to identify the beneficial effects of pizza.
Internationalization patterns among speciality food companies: some Italian case study evidence
Authors: Testa Stefania 
Published: October 2011

PurposeThe purpose of this paper is to contribute to a better understanding of internationalization patterns among speciality food small to medium‐sized enterprises (SMEs), investigating dimensions that may have a bearing on such patterns, using a series of case studies. In particular the investigation seeks to gain new insights about differences among companies in their internationalization patterns. These differences are examined in a framework which tries to relate three company‐level dimensions (market, technology and space) to internationalization patterns. The three dimensions are derived from the constructs developed by Storper and Salais, and Straete.Design/methodology/approachTwo research questions (RQs) are formulated: Is there a relationship between the internationalization pace of speciality food SMEs and their technology, market, and space dimensions? Is there a relationship between the internationalization modes of speciality food SMEs and their technology, market, and space dimensions? A qualitative approach was adopted and cases from a broad dataset were used. The present research is an explorative research: it is intended to provide insights from which hypotheses might be developed.FindingsThis paper provides an empirical and conceptual contribution to the food internationalization debate. On the empirical side, it provides new evidence on speciality food internationalization, showing a rather diversified set of internationalization patterns, both in terms of pace and modes. On the conceptual side, it shows that the three dimensions of technology, market and space may help to enrich the comprehension of internationalization phenomena. While data collected seem not to provide insights from which hypotheses might be developed concerning RQ1, they seem on the contrary to provide useful insights concerning RQ2.Research limitations/implicationsLimitations of the research generally relate to the use of a small sample. Future research should strive to obtain larger samples, develop a set of relevant finer‐grained hypotheses and test those using appropriate statistical techniquesPractical implicationsIdentifying the impact that the three dimensions might have on internationalization patterns and vice versa may help to focus on these specific elements when companies make their internationalization decisions. On the same line, public policy agencies could benefit from these first results for better clustering companies targeting their internationalization supporting initiatives.Originality/valueThe findings add to the limited body of knowledge on the key influences on internationalization patterns within the food sector.
East Asian cuisine perceptions in New York City between 1997 and 2007
Authors: Choi Jia , Lee Jong‐Mee , Cho Mi‐Sook 
Published: October 2011

PurposeThe primary aim of this paper is to reveal the changes in perception of East Asian cuisine (Chinese, Japanese, Korean, Thai, and Vietnamese) in New York City between 1997 and 2007. Through analysis of data collected from Zagat Survey food reviews, the research seeks to explore trends regarding each cuisine's social status, quality, and also to observe general comparisons between each ethnicity's cuisine. The secondary aim is to evaluate how each cuisine is currently perceived in the city that is not only beaming with culinary delights, but also deemed the “Restaurant capital of the world”.Design/methodology/approachUsing the Zagat Survey New York City 1997 and 2007, quantitative analyses were performed using the scores for comparison purposes. The mean and the standard deviations are calculated in terms of food, decor, service, and price. The t‐test was used to verify whether there have been statistically meaningful changes in each cuisine for the past ten years in the Zagat Survey.FindingsIn terms of popularity, the number of Japanese restaurants has significantly increased in ten years while that of Chinese restaurants decreased about 30 percent. According to the t‐tests, Japanese showed most significant changes in almost all aspects. Thai cuisine also demonstrated remarkable improvements, especially, in decor and service. Korean and Chinese cuisine did not show a noticeable change in food, decor, and service. Only the price showed a little change for these cuisines. Vietnamese cuisine achieved a significant progress in food while no enhancement in other aspects.Research limitations/implicationsBecause the scope of the research was “general” restaurants in New York City, the discussion on their price range, quality of food, decor, and service, the type of restaurant under observation was inevitably limited.Practical implicationsThe research can help in marketing and development of new restaurants for it provides some insight into the characteristics of each ethnic cuisine and trend changes of restaurants.Originality/valueThe research presented in the paper can be applied both by practitioners and academics in the fields of food service management.