Simple Link Research Articles

Refundable Advance Purchase Tickets and Advance Purchase Restrictions under Aggregate Demand Uncertainty

This paper rationalizes the use of discounted refundable advance purchase tickets and advance purchase restrictions in context of models with costly capacity and aggregate demand uncertainty. We show how a monopolist on such markets can improve upon pricing mechanisms, previously proposed in the related literature for markets for perishable products, characterized by uncertain demand and costly capacity (which include but are not limited to such important industries as airlines, hotels, restaurants, car rentals, and live performances). Our model provides a simple link between two strains of literature (one modeling non-refundable discounted tickets with demand uncertainty specified through states of demand, and the other analyzing fully or partially refundable contracts while treating demand uncertainty at the customer level).

Towards modelling complex robot training tasks through system identification

Previous research has shown that sensor–motor tasks in mobile robotics applications can be modelled automatically, using NARMAX system identification, where the sensory perception of the robot is mapped to the desired motor commands using non-linear polynomial functions, resulting in a tight coupling between sensing and acting — the robot responds directly to the sensor stimuli without having internal states or memory. However, competences such as for instance sequences of actions, where actions depend on each other, require memory and thus a representation of state. In these cases a simple direct link between sensory perception and the motor commands may not be enough to accomplish the desired tasks. The contribution of this paper to knowledge is to show how fundamental, simple NARMAX models of behaviour can be used in a bootstrapping process to generate complex behaviours that were so far beyond reach. We argue that as the complexity of the task increases, it is important to estimate the current state of the robot and integrate this information into the system identification process. To achieve this we propose a novel method which relates distinctive locations in the environment to the state of the robot, using an unsupervised clustering algorithm. Once we estimate the current state of the robot accurately, we combine the state information with the perception of the robot through a bootstrapping method to generate more complex robot tasks: We obtain a polynomial model which models the complex task as a function of predefined low level sensor–motor controllers and raw sensory data. The proposed method has been used to teach Scitos G5 mobile robots a number of complex tasks, such as advanced obstacle avoidance, or complex route learning.

MouseBook: an integrated portal of mouse resources

The MouseBook (http://www.mousebook.org) databases and web portal provide access to information about mutant mouse lines held as live or cryopreserved stocks at MRC Harwell. The MouseBook portal integrates curated information from the MRC Harwell stock resource, and other Harwell databases, with information from external data resources to provide value-added information above and beyond what is available through other routes such as International Mouse Stain Resource (IMSR). MouseBook can be searched either using an intuitive Google style free text search or using the Mammalian Phenotype (MP) ontology tree structure. Text searches can be on gene, allele, strain identifier (e.g. MGI ID) or phenotype term and are assisted by automatic recognition of term types and autocompletion of gene and allele names covered by the database. Results are returned in a tabbed format providing categorized results identified from each of the catalogs in MouseBook. Individual result lines from each catalog include information on gene, allele, chromosomal location and phenotype, and provide a simple click-through link to further information as well as ordering the strain. The infrastructure underlying MouseBook has been designed to be extensible, allowing additional data sources to be added and enabling other sites to make their data directly available through MouseBook.

Pipelined Chebyshev Functional Link Artificial Recurrent Neural Network for Nonlinear Adaptive Filter

A novel nonlinear adaptive filter with pipelined Chebyshev functional link artificial recurrent neural network (PCFLARNN) is presented in this paper, which uses a modification real-time recurrent learning algorithm. The PCFLARNN consists of a number of simple small-scale Chebyshev functional link artificial recurrent neural network (CFLARNN) modules. Compared to the standard recurrent neural network (RNN), those modules of PCFLARNN can simultaneously be performed in a pipelined parallelism fashion, and this would lead to a significant improvement in its total computational efficiency. Furthermore, contrasted with the architecture of a pipelined RNN (PRNN), each module of PCFLARNN is a CFLARNN whose nonlinearity is introduced by enhancing the input pattern with Chebyshev functional expansion, whereas the RNN of each module in PRNN utilizing linear input and first-order recurrent term only fails to utilize the high-order terms of inputs. Therefore, the performance of PCFLARNN can further be improved at the cost of a slightly increased computational complexity. In addition, due to the introduced nonlinear functional expansion of each module in PRNN, the number of input signals can be reduced. Computer simulations have demonstrated that the proposed filter performs better than PRNN and RNN for nonlinear colored signal prediction, nonstationary speech signal prediction, and chaotic time series prediction.

Calcium Regulation of an Actin Spring

Calcium is essential for many biological processes involved in cellular motility. However, the pathway by which calcium influences motility, in processes such as muscle contraction and neuronal growth, is often indirect and complex. We establish a simple and direct mechanochemical link that shows how calcium quantitatively regulates the dynamics of a primitive motile system, the actin-based acrosomal bundle of horseshoe crab sperm. The extension of this bundle requires the continuous presence of external calcium. Furthermore, the extension rate increases with calcium concentration, but at a given concentration, we find that the volumetric rate of extension is constant. Our experiments and theory suggest that calcium sequentially binds to calmodulin molecules decorating the actin filaments. This binding leads to a collective wave of untwisting of the actin filaments that drives bundle extension.

Nonlinear dynamic system identification using pipelined functional link artificial recurrent neural network

A computationally efficient pipelined functional link artificial recurrent neural network (PFLARNN) is proposed for nonlinear dynamic system identification using a modification real-time recurrent learning (RTRL) algorithm in this paper. In contrast to a feedforward artificial neural network (such as a functional link artificial neural network (FLANN)), the proposed PFLARNN consists of a number of simple small-scale functional link artificial recurrent neural network (FLARNN) modules. Since those modules of PFLARNN can be performed simultaneously in a pipelined parallelism fashion, this would result in a significant improvement in its total computational efficiency. Moreover, nonlinearity of each module is introduced by enhancing the input pattern with nonlinear functional expansion. Therefore, the performance of the proposed filter can be further improved. Computer simulations demonstrate that with proper choice of functional expansion in the PFLARNN, this filter performs better than the FLANN and multilayer perceptron (MLP) for nonlinear dynamic system identification.

Backward and Simultaneous Masking in Children With Grammatical Specific Language Impairment: No Simple Link Between Auditory and Language Abilities

We investigated claims that specific language impairment (SLI) typically arises from nonspeech auditory deficits by measuring tone-in-noise thresholds in a relatively homogeneous SLI subgroup exhibiting a primary deficit restricted to grammar (Grammatical[G]-SLI). Fourteen children (mostly teenagers) with G-SLI were compared to age-, vocabulary-, and grammar-matched control children on their abilities to detect a brief tone in quiet and in the presence of a masking noise. The tone occurred either simultaneously with the noise or just preceding it (backward masking). Maskers with and without a spectral notch allowed estimates of frequency selectivity. Group thresholds for the G-SLI children were never worse than those obtained for younger controls but were higher in both backward and simultaneous masking than in age-matched controls. However, more than half of the G-SLI group (8/14) were within age-appropriate limits for all thresholds. Frequency selectivity in the G-SLI group was normal. Within control and G-SLI groups, no threshold correlated with measures of vocabulary, grammar, or phonology. Nor did the language deficit in the G-SLI children vary with the presence or absence of auditory deficits. The auditory processing deficits sometimes found in children with SLI appear unlikely to cause or maintain the language impairment.

An exploratory analysis of error components in hydrological regression modeling

The use of the generalized least squares (GLS) technique for estimation of hydrological regression models has become good practice in hydrology. Through a regression model, a simple link between a particular hydrological variable and a set of catchment descriptors can be established. The regression residuals can be treated as the sum of sampling errors in the hydrological variable and errors in the regression model. This article presents a method for exploring and developing a parameterized form for the cross‐correlation between the regression model errors. Given an initial GLS analysis, a reweighted set of regression residuals is defined such that the covariance of these residuals is essentially similar to that of the model errors. The cross‐products of the reweighted regression residuals, pooled within bins, are then used to identify a structure and to fit a parameterized form for the cross‐correlations of the regression errors. These estimated cross‐correlations are then used to inform improved GLS and reweighting steps, leading to a recursive procedure. The main advantage of the recursive GLS procedure is that it allows for a simple demonstration of the actual existence of model error correlation as well as for exploring suitable models for the correlation. However, while the procedure for identifying a parametric description for the model error correlation is reasonable, estimation of the parameters within the recursive procedure is affected by the data‐binning step. Thus it is suggested that once a structure for the correlation has been decided, further data analysis—such as final decisions about variables included in the regression model and final estimation of parameters—should be undertaken within a maximum likelihood framework. The procedure has been tested on annual maximum flow data from 602 catchments located throughout the United Kingdom. A set of Monte Carlo experiments further confirmed the ability of the recursive GLS procedure to correctly identify and estimate the true model error correlation.

The microvasculature of invasive ductal breast carcinoma: a sterological approach.

Abstract Abstract #1057 Background:
 Microvessel density (MVD) is a commonly used parameter to describe tumour vascularity and has been widely studied as a possible prognosticator in breast cancer. Other descriptors of vascular beds have been developed and have been applied to a variety of systems including the reproductive and nervous systems. These stereological approaches are providing objective unbiased assessment of various vascular beds.
 Aim:
 The aim of this pilot study was to use stereological methods to describe the vasculature in invasive ductal breast carcinoma, to test the hypothesis that microvasculature anatomy effects Tumor Grade, Size and Nodal Status.
 Methods:
 A cohort of 51 breast cancer patients with pre-menopausal invasive ductal carcinoma and moderate NPI was identified.Sections were stained with CD34 using the automated Ventana Discovery staining platform. A number of stereological parameters were estimated in three tissue compartments (gland,stroma and adipose):Number per Unit area (Na), Length Density (Lv) and Radial Diffusion Distance. Data was analysed using Analyses of Variance methods using Minitab© Statistical software.
 Results:
 There was no significant difference in the radial diffusion difference when groups were analysed by Grade Size and Nodal Status. Similar results were found for Na and Lv
 Conclusion:
 This study suggests that there is no simple link between tumor vasculature and Grade, size and nodal status in Invasive Ductal Breast Carcinoma. This study illustrates the potential usefulness of the stereological approach in the study of vascular beds in breast cancer studies by providing access to potentially physiologically relevant anatomical parameters of microvasculature beds. Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 1057.

Gamer's Facial Cloning for Online Interactive Games

Virtual illustration of a human face is essential to enhance the mutual interaction in a cyber community. In this paper we propose a solution to solve two bottlenecks in facial analysis and synthesis for an interactive system of human face cloning for non-expert users of computer games. Tactical maneuvers of the gamer make single camera acquisition system unsuitable to analyze and track the face due to its large lateral movements. For an improved facial analysis system, we propose to acquire the facial images from multiple cameras and analyze them by multiobjective 2.5D Active Appearance Model (MOAAM). Facial morphological dissimilarities between a human face and an avatar make the facial synthesis quite complex. To successfully clone or retarget the gamer facial expressions and gestures on to an avatar, we introduce a simple mathematical link between their appearances. Results obtained validate the efficiency, accuracy and robustness achieved.

Rd network services

With the Internet offering a single best-effort service, there have been numerous proposals of diversified network services that align better with the divergent needs of different distributed applications. The failure of these innovative architectures to gain wide deployment is primarily due to economic and legacy issues, rather than technical shortcomings. We propose a new paradigm for network service differentiation where design principles account explicitly for the multiplicity of Internet service providers and users as well as their economic interests in environments with partly deployed new services. Our key idea is to base the service differentiation on performance itself, rather than price. The proposed RD (Rate-Delay) services enable a user to choose between a higher transmission rate or low queuing delay at a congested network link. An RD router supports the two services by maintaining two queues per output link and achieves the intended rate-delay differentiation through simple link scheduling and dynamic buffer sizing. After analytically deriving specific rules for RD router operation, we conduct extensive simulations that confirm effectiveness of the RD services geared for incremental deployment in the Internet.

A Study of Gas and Rain Propagation Effects at 48 GHz for HAP Scenarios

The atmosphere and rainfall significantly limit the performance of millimeter wave links and this has to be taken into account, particularly, during planning of high altitude platform (HAP) networks. This paper presents results from the measurement and simulation of these phenomena. A simulation tool from our previous analyses of terrestrial point-to-multipoint systems has been modified for HAP systems. Based on a rainfall radar database and gas attenuation characteristics as measured by a Fabry-Perot resonator, the performance of a simple link, two-branch diversity links, and more complicated HAP scenarios are discussed.

Simple Robust Linkages between CDS and Equity Options

We test a theory that provides a simple and robust link between market prices of credit default swaps (CDS) and equity options. The theory links the CDS spread to the market prices of vertical spreads of American put options which are sufficiently out-of-the-money. T he linkage is established under a general class of stock price dynamics for which the default event affects only the state space in which stock prices evolve. Specifically, stock prices are assumed to be bounded below by a barrier B > 0 strictly before the default event, and to drop below an alternative barrier A < B at the default time. We allow random stock price evolution after default, so long as it is bounded above by A. We suppose that investors can take a static position in at least two co-terminal American put options struck within the default corridor [A, B]. We show that a vertical spread of such options scaled by the spread between the two strikes replicates a standardized credit insurance contract that pays one dollar at default whenever the company defaults prior to the option expiry and zero otherwise. Given the above state space behavior, we show that this simple replicating strategy is robust to the details of the pre-default stock price dynamics, the post-d efault stock price dynamics, interest rate dynamics, and default arrival rate fluctuations. We use the value of the American put spread to infer risk-neutral default probabilities and compare them to the default probabilities estimated from CDS spreads on the same reference company. Collecting data from both markets on several reference companies with significant default probabilities, we identify a strong correlation between the defa ult probabilities inferred from the two markets, and find that deviations between the two estimates help predict f uture movements in both markets.

Non-Faradaic electrochemical detection of protein interactions by integrated neuromorphic CMOS sensors

Electronic detection of the binding event between biotinylated bovine serum albumen (BSA) and streptavidin is demonstrated with the chemoreceptive neuron MOS (CνMOS) device. Differing from the ion-sensitive field-effect transistors (ISFET), CνMOS, with the potential of the extended floating gate determined by both the sensing and control gates in a neuromorphic style, can provide protein detection without requiring analyte reference electrodes. In comparison with the microelectrode arrays, measurements are gathered through purely capacitive, non-Faradaic interactions across insulating interfaces. By using a (3-glycidoxypropyl)trimethoxysilane (3-GPS) self-assembled monolayer (SAM) as a simple covalent link for attaching proteins to a silicon dioxide sensing surface, a fully integrated, electrochemical detection platform is realized for protein interactions through monotone large-signal measurements or small-signal impedance spectroscopy. Calibration curves were created to coordinate the sensor response with ellipsometric measurements taken on witness samples. By monitoring the film thickness of streptavidin capture, a sensitivity of 25ng/cm2 or 2Å of film thickness was demonstrated. With an improved noise floor the sensor can detect down to 2ng/(cm2mV) based on the calibration curve. AC measurements are shown to significantly reduce long-term sensor drift. Finally, a noise analysis of electrochemical data indicates 1/fα behavior with a noise floor beginning at approximately 1Hz.

Democracy and Education: Empowering Students to Make Sense of Their World

EVER wonder why democratic societies are unrivaled in expanding knowledge and creativity? There is a simple yet vital link between democracy and education, and it is found in how we learn best. If you have studied educational psychology or learning theory, you probably have insight into the causes of this phenomenon. If your instructional practices include such things as self-directed learning, self-reflection, or action research, you are probably well aware of the practical mechanism underlying this productivity even if you don't know it by name. It is a fundamental belief under our system of governance that education is necessary for democracy. Less recognized is the equally important principle that democracy is necessary for education. Looking closely at the relationship between democracy and education reveals a common foundation in a learning mechanism that is as important for classroom practice as it is for a democratic society. In Democracy and Education, Dewey defines education as the reconstruction or reorganization of experience which adds to the meaning of experience and which increases the ability to direct the course of subsequent (1) Education, like democracy, is fundamentally empowerment. Both provide the participants with the means to shape and direct their experiences. educational process in a democratic society, even in the most autocratic of classrooms and institutions, is grounded in basic freedoms. These freedoms exist beyond the particular classroom and institution, if not within them. From a learning perspective, the most important of these freedoms is the freedom to choose, to act on that choice, and to experience the results of those actions. Instructional practices that include self-reflection and action research are based on the idea that we learn by following our thoughts and actions and examining their consequences. By choosing a course of action and experiencing the results, our beliefs and understandings about the world, how it works, and how we fit into it are reinforced or modified. In describing intelligence, Jean Piaget echoes this fundamental play between thinking, acting, and learning: The essential functions of intelligence consist in understanding and in inventing, in other words in building up structures by structuring (2) We learn by constructing meaning from our experiences. We reconstruct, reorganize, and direct our experiences as we attempt to make sense of our world. Our understanding of the world is constructed through what we make of our experiences, how we interpret them, and how these interpretations are integrated into our knowledge and beliefs. These learnings provide the mental structures and dispositions that influence and direct subsequent experience. We continually make choices in all of our thoughts and actions. Ulric Neisser wrote about the cycle of learning: of all the possibilities presented in our environment, our thought processes or mental structures guide our perceptual awareness, which samples the available information. As we choose to focus our attention, what we experience serves to modify or reinforce these structures, which guide further perceptual exploration and experience. (3) This fundamental learning mechanism underlies the rich and productive relationship between democracy and education. Learning is the process of constructing meaning or structuring reality. It is necessarily a self-directed process contingent on individual choice and action. critical connection between democracy and education is that democratic social institutions are produced and sustained by the same progressive mechanism: the freedom to learn from experience, to build on experience, and to use this knowledge to direct the course of subsequent experience. …

Cooperative Strategy for a Wheelchair and a Robot to Climb and Descend a Step

This paper discusses a cooperative strategy that enables a wheelchair and a wheeled robot to climb and descend a step. In this method, not only does the robot assist the wheelchair user, but also the user assists the robot to overcome the step. The research indicates the feasibility of this new cooperative strategy between a physically disabled person and a personal robot that is not designed for high-level performance. The two vehicles (the wheelchair and the wheeled robot) are connected by a simple link mechanism, the two connecting positions of which are free joints. This method is especially affected by the link positions. A numerical calculation clarifies the combinations of the two link positions to avoid a collision between each vehicle and to overcome a step at the same time. The result of the simulations indicate that it is necessary to change the link positions to climb and descend a step safely. The experimental results show that this method is effective.

車輪型ロボットと車いすによる協調段差乗り上げ手法

This paper describes a method of cooperative strategy which enables a wheelchair and a wheeled robot to climb a step by a simple link mechanism which connects between them. We perform a numerical calculation to clarify the combination of two supporting positions of the connecting link that connects the two vehicles which enable them to climb a step and is stable at the same time. We conclude from the result of the simulation that it is necessary to change the link positions to climb a step safely. We ascertain the effectiveness of this method by means of experiments.

A new approach for routing and wavelength assignment for permanent and reliable wavelength paths in wide all-optical WDM networks

This article proposes a new approach for routing and wavelength assignment (RWA) for permanent and reliable wavelength paths (WP) in wide all-optical WDM networks with wavelength continuity constraint. Given a number of available wavelengths on each optical fiber, for each simple link failure of the network, we seek to maximize the number of satisfied requests for connections. This is known as RWAP problem. In our algorithm, called RWA with Minimum Loaded Link for Permanent and Reliable wavelength paths (MLL-PR), routing is based on the search for the optimal path while trying to minimize the maximum load on the links of the network in order to minimize the maximum link capacity and then minimize the number of dropped lightpaths after any link failure. The wavelength assignment is based on a graph coloring method using tabu-search. A series of experiments using two well-known networks (ARPANET and NSFNET) have been carried out in order to evaluate the performance of our approach, in terms of the number of blocked demands, for different failure scenarios. Generally, our results are better than those provided by the current solving approaches taken as reference.

Paths to foreign markets: Does distance to market affect firm internationalisation?

An idea widely shared among international business scholars, economists and geographers is that geographic, cultural and psychic distance to market affects firm internationalisation in a number of ways. However, evidence for this broad proposition remains inconclusive. This study provides a comprehensive assessment of four separate hypotheses pertaining to the location of markets, the sequence of market entry, the rate of international expansion, and the relationship between sequentially-linked markets. In contrast with previous studies, the analysis is based on a large sample of non-repetitive foreign market entries ( n=1132) made by diverse exporters in dissimilar locations within a single country (China). Market entry data thus exhibit substantial variation on the constructs of interest. The results reveal virtually no support for three traditional hypotheses linking distance to market with the sequence of markets entered and the rate of foreign expansion. This study challenges the long-held notion that there is a simple link between distance and market entry sequence. However, this study provides arguably the first demonstration of the “near-market effect” in the context of low-risk entry modes such as exporting. Specifically, the results show that consecutive export locations tend to be culturally related suggesting that exporters are able to transfer learning between similar markets.

A Reduced-Switch-Count Five-Level Inverter With Common-Mode Voltage Elimination for an Open-End Winding Induction Motor Drive

The paper presents a five-level inverter scheme with reduced power circuit complexity for an induction motor drive. The scheme is realized by cascading conventional two-level and three-level neutral point clamped inverters in conjunction with an open-end winding three-phase induction motor drive. An inverter control scheme with common-mode voltage (CMV) elimination, along with a simple DC link voltage control, is developed by using only switching states with zero CMV for the entire modulation range. Theoretical considerations are experimentally verified for a variety of operating conditions.