Search

In this work, we present a perspective on the role machine intelligence can play in supporting human abilities. In particular, we consider research in rehabilitation technologies such as prosthetic devices, as this domain requires tight coupling between human and machine. Taking an agent-based view of such devices, we propose that human–machine collaborations have a capacity to perform tasks which is a result of the combined agency of the human and the machine. We introduce communicative capital as a resource developed by a human and a machine working together in ongoing interactions. Development of this resource enables the partnership to eventually perform tasks at a capacity greater than either individual could achieve alone. We then examine the benefits and challenges of increasing the agency of prostheses by surveying literature which demonstrates that building communicative resources enables more complex, task-directed interactions. The viewpoint developed in this article extends current thinking on how best to support the functional use of increasingly complex prostheses, and establishes insight toward creating more fruitful interactions between humans and supportive, assistive, and augmentative technologies.

During every waking moment, we must engage with our environments, the people around us, the tools we use, and even our own bodies to perform actions and achieve our intentions. There is a spectrum of control that we have over our surroundings that spans the extremes from full to negligible. When the outcomes of our actions do not align with our goals, we have a tremendous capacity to displace blame and frustration on external factors while forgiving ourselves. This is especially true when we cooperate with machines; they are rarely afforded the level of forgiveness we provide our bodies and often bear much of our blame. Yet, our brain readily engages with autonomous processes in controlling our bodies to coordinate complex patterns of muscle contractions, make postural adjustments, adapt to external perturbations, among many others. This acceptance of biological autonomy may provide avenues to promote more forgiving human-machine partnerships. In this perspectives paper, we argue that striving for machine embodiment is a pathway to achieving effective and forgiving human-machine relationships. We discuss the mechanisms that help us identify ourselves and our bodies as separate from our environments and we describe their roles in achieving embodied cooperation. Using a representative selection of examples in neurally interfaced prosthetic limbs and intelligent mechatronics, we describe techniques to engage these same mechanisms when designing autonomous systems and their potential bidirectional interfaces.

Learning to get by without an arm or hand can be very challenging, and existing prostheses do not yet fill the needs of individuals with amputations. One promising solution is to improve the feedback from the device to the user. Towards this end, we present a simple machine learning interface to supplement the control of a robotic limb with feedback to the user about what the limb will be experiencing in the near future. A real-time prediction learner was implemented to predict impact-related electrical load experienced by a robot limb; the learning system’s predictions were then communicated to the device’s user to aid in their interactions with a workspace. We tested this system with five able-bodied subjects. Each subject manipulated the robot arm while receiving different forms of vibrotactile feedback regarding the arm’s contact with its workspace. Our trials showed that using machine-learned predictions as a basis for feedback led to a statistically significant improvement in task performance when compared to purely reactive feedback from the device. Our study therefore contributes initial evidence that prediction learning and machine intelligence can benefit not just control, but also feedback from an artificial limb. We expect that a greater level of acceptance and ownership can be achieved if the prosthesis itself takes an active role in transmitting learned knowledge about its state and its situation of use.

Nursery production of walnut seedlings is a 2-year process, during which crown gall, caused by Agrobacterium tumefaciens, often develops at grafting wounds. In this study, the spread of crown gall via contaminated tools and the efficacy of several disinfectants against A. tumefaciens were demonstrated. The cationic surfactants benzalkonium chloride (BC), cetyltrimethylammonium bromide (CTAB), and Physan 20 eliminated 100% of the A. tumefaciens population in water suspensions treated at 7, 5, and 2 ppm, respectively. Sodium hypochlorite eliminated 100% of the A. tumefaciens population at 0.5 ppm. Sodium hypochlorite efficacy, however, was reduced by 64% in the presence of total solids (0.7 g/ml) which are commonly found in field situations. At similar concentrations of total solids, the efficacy of cationic surfactants decreased, on average, by only 13%. The minimum effective treatment needed to eliminate A. tumefaciens on infested scalpels was a 5-s exposure to BC or CTAB at 5,000 ppm (0.5%). Infested scalpels treated with BC or CTAB at less than 5,000 ppm caused gall formation in 14 ± 7% of cuts made on Datura stramonium stems. This was significantly less than the tumor incidence (100%) in cuts made with inoculated blades not treated BC or CTAB.

Greater than 75% of English walnut production in the United States occurs on the walnut rootstock Juglans hindsii × J. regia ‘Paradox’, which is highly susceptible to infection by Agrobacterium tumefaciens. When seed were germinated and grown in the presence of A. tumefaciens, in the absence of wounding, 94% of the seedlings exhibited tumors while 89% contained systemic A. tumefaciens populations. When seedlings were wound inoculated, A. tumefaciens established endophytic populations in stem tissue and often migrated from the site of infection. Distribution of A. tumefaciens in the stem was random and may exhibit seasonal variation. A. tumefaciens populations in root tissue were more readily detected than in stem tissue and may serve as a reservoir for subsequent infection of the aerial portions of the tree. Importantly, 7% of inoculated, asymptomatic seedlings contained endophytic populations of A. tumefaciens. In all, 17% of seedlings inoculated as seeds developed galls at secondary stem-wound sites. These results provide an ecological and epidemiological foundation upon which to modify existing tree-handling practices in both nursery and orchard production environments to manage crown gall incidence.

The walnut rootstock ‘Paradox’ (Juglans hindsii × J. regia) is susceptible to Agrobacterium tumefaciens, which often results in a high incidence of crown gall in nursery or walnut production orchards. Though A. tumefaciens is susceptible to the commonly used preplant soil fumigants, crown gall incidence can rise above acceptable levels. We examined the ability of Paradox seed to acquire A. tumefaciens as a function of harvest method used prior to planting. Over a 2-year period at two participating commercial nurseries, Paradox seed were collected directly from the mother tree without contacting the soil or gathered after sitting on the orchard floor for up to 28 days. A. tumefaciens was never detected in or on the 2,650 seeds collected directly from the mother tree. Both virulent and avirulent A. tumefaciens strains were detected in and on the husk of nuts incubated on the orchard floor at a frequency directly proportional to the time spent on the orchard floor. Regardless of A. tumefaciens contamination in or on the husk, A. tumefaciens was never detected in the seed interior. Avoiding soilborne populations of A. tumefaciens at the time of seed collection will play an important role in managing crown gall.

Paradox (Juglans hindsii × J. regia), the dominant rootstock used in California, USA walnut production, has many desirable horticultural characteristics, but is highly susceptible to crown gall. Crown gall, caused by the bacterium Agrobacterium tumefaciens, is not consistently controlled with soil fumigation. This observation, in conjunction with observations of galls occurring in above ground grafting wounds, led to the hypothesis that A. tumefaciens inoculum may be endophytic in walnut seedlings. Paradox seeds collected directly from commercial Paradox mother trees (i.e., Juglans hindsii) were free of A. tumefaciens. Sampling conducted at multiple times during seed production revealed that seed-borne A. tumefaciens populations increased as a function of contact time with the orchard floor. In greenhouse experiments, seeds inoculated with A. tumefaciens produce seedlings with galls at the crown and/or roots in the absence of artificial wounding. Endophytic populations of A. tumefaciens were also found in shoot and root tissue. These data suggest that A. tumefaciens inoculum may exist as a resident endophyte and that timely seed collection, limiting contact with the orchard floor, may be an important first step in preventing crown gall disease of walnut.

Seven methods of spatial interpolation were compared to determine their suitability for estimating daily mean wind speed surfaces, from data recorded at nearly 190 locations across England and Wales. The eventual purpose of producing such surfaces is to help estimate the daily spread of pathogens causing crop diseases as they move across regions. The interpolation techniques included four deterministic and three geostatistical methods. Quantitative assessment of the continuous surfaces showed that there was a large difference between the accuracy of the seven interpolation methods and that the geostatistical methods were superior to deterministic methods. Further analyses, testing the reliability of the results, showed that measurement accuracy, density, distribution and spatial variability had a substantial influence on the accuracy of the interpolation methods. Independent wind speed data from ten other dates were used to confirm the robustness of the best interpolation methods. © Crown copyright 2007. Reproduced with the permission of Her Majesty's Stationery Office. Published by John Wiley & Sons, Ltd.

For wheat, the optimum time to apply fungicide to control disease on a given leaf layer is usually at, or shortly after, full leaf emergence. Data from field experiments on barley were used to investigate whether the same relationship was applicable to control of leaf blotch on barley. Replicated plots of winter barley were sown in the autumns of 1991, 1992 and 1993 at sites in southwest England with high risk of Rhynchosporium secalis infection. Single fungicide treatments at four doses (0·25, 0·5, 0·75 or 1·0 times the label rate) were applied at one of eight different spray times, starting in mid-March in each year, with intervals of 10–11 days between spray timings. Disease was assessed every 10–11 days and area under the disease progress curve (AUDPC) values were used to construct fungicide dose by spray time response surfaces for each of the upper four leaves, for each year. Spray timings shortly before leaf emergence were found to minimize the AUDPC for each year and leaf layer, and also the effective dose (the dose required to achieve a specified level of control), similar to wheat. Fungicide treatments on barley were effective for a longer period before leaf emergence than afterwards, probably because treatments before emergence of the target leaf reduced inoculum production on leaves below. This partly explains why fungicides tend to be applied earlier in the growth of barley compared with wheat.

Batches of two winter wheat cultivars (Riband and Apollo) were inoculated with conidia of Mycosphaerella graminicola at weekly intervals over a 2 year period. Following 72 h incubation, plants were placed in ambient temperatures ranging between -7 and 32degreesC with mean batch temperatures of 2.9-20.2degreesC. Latent period until the first visible symptoms ranged between 11 and 42 days. The relationship between development of lesions and accumulated thermal time was described using a shifted cumulative gamma distribution model. The model provided good estimates of lesion development with r(2)>0.92 for both cultivars. Base temperatures, below which the pathogen did not develop, were estimated from the model as approximately -2.4degreesC for the two cultivars. Latent period was estimated as being 250 and 301 degree-days above the estimated base temperature, when defined as time from inoculation to first lesion and time to 50% of maximal lesions, respectively, for cv. Riband. The values for cv. Apollo were similar, but with estimates of thermal time periods c. 5% higher. The relationship between mean temperature and inverse latent period, expressed as days either to first lesion or to 50% of maximal lesions, was best described by a linear regression with r(2)>0.96 for both cultivars. The opportunity for plants to outgrow disease was reduced when prolonged periods of cold temperature occurred, because the base temperature for growth of the pathogen was less than that for the crop.

Two models for predicting Septoria tritici on winter wheat (cv. Riband) were developed using a program based on an iterative search of correlations between disease severity and weather. Data from four consecutive cropping seasons (1993/94 until 1996/97) at nine sites throughout England were used. A qualitative model predicted the presence or absence of Septoria tritici (at a 5% severity threshold within the top three leaf layers) using winter temperature (January/February) and wind speed to about the first node detectable growth stage. For sites above the disease threshold, a quantitative model predicted severity of Septoria tritici using rainfall during stem elongation. A test statistic was derived to test the validity of the iterative search used to obtain both models. This statistic was used in combination with bootstrap analyses in which the search program was rerun using weather data from previous years, therefore uncorrelated with the disease data, to investigate how likely correlations such as the ones found in our models would have been in the absence of genuine relationships.

An electronic sensor, based on a piezoelectric transducer, was tested in the laboratory using simulated raindrops, and in natural rainfall. Data were also collected for splash dispersal using tracer dyes in laboratory experiments and the Long Ashton splashmeter in field experiments. Droplets impacting on sensor produce sound waves that are detected by an omnidirectional microphone sealed within an acoustic chamber. An electrical charge, proportional to the sound wave, is produced by the microphone and is converted to a categorical scale and then stored to provide an accumulation of impacts over a specified period of time. Calibration of the sensor was done using single-droplet impacts of known mass and impacting velocity. A linear relationship was shown between the categorical scale and the kinetic energy of impacting droplets (adjusted r2 = 0.99). The best relationship fitted between splash dispersal from dye cup, and kinetic energy was a second-order polynomial (adjusted r2 > 0.99). Splash height, recorded by the Long Ashton splashmeter during 41 natural rainfall events, was correlated closely with sensor output (adjusted r2 = 0.87). Our studies indicate that the sensor provides quantitative data which could be incorporated into disease management systems to provide estimates of inoculum dispersal gradients within crop canopies.

Establishment of the University of Florida Cooperative Forest Genetics Research Program's clone banks provided an opportunity to look at scion maturation effects on growth and reproduction of many grafted slash pine clones. In 1988 and 1989, clone banks were established in nine locations in the Southeastern United States. Over 460 scion clones varying from 5 to greater than 40 years old from time of seed germination (chronological age) were grafted into the clone banks. Comparisons of diameter growth, height growth, lateral branch number and female and male strobili production were made annually for six years after grafting. Within slash pine clone banks, there were significant effects due to scion chronological age. Chronologically older scions (backward selections) grew less, had fewer branches and produced only a few more female strobili than chronologically younger material (forward selections). Forward selections produced significantly more catkin clusters than backward selections. By year six, there was no significant difference in numbers of female strobili per tree between backward and forward scions, but forward selections produced about 2.5 times as many catkin clusters as the backward selections. Similar effects on growth and reproduction due to chronological age were also found among clones within the forward selections, with older selections growing more slowly and producing fewer catkin clusters. The size and breadth of this study lends strong support to the idea that these patterns of growth will occur for grafted slash pine in any location throughout its native range.

Over a period of three crop seasons the spatial patterns of some common diseases of winter wheat were investigated at growth stages (GS) 31/33 and 59/61. A large-scale sampling procedure, using randomly positioned transects and based on the theory of autocorrelation analysis, is described. This novel technique enables valid tests of significance to be made on the autocorrelation coefficients calculated. The most complete data obtained were for Septoria tritici blotch which was found to have a near random pattern on scales between 31 cm and 31 m at the growth stages investigated. However, the severity of S. tritici blotch was found to be autocorrelated at scales below 1 m in some fields. With the exceptions of powdery mildew at GS 31/33 and yellow rust at GS 59/61, the other diseases also exhibited a near random pattern. Therefore, almost any convenient sampling pattern, with reasonable overall coverage, will be adequate to obtain samples for monitoring winter wheat at growth stages 31 and 59.

Generally, it is recognized that inocula of Septoria tritici present on the basal leaves of winter wheat crops are spread towards the top of the canopy by splashy rainfall. This mechanism of inoculum dispersal is commonly accepted to be a key limit on disease progression. Therefore, attempts to forecast epidemics of S. tritici often quantify rainfall by some means, but largely ignore measurement of pathogen and host variables. In the present study, we show that new wheat leaves emerge initially at a height below established leaves that can contain sporulating lesions of S. tritici. This presents the possibility of horizontal inoculum transfer, even without splashy rainfall. The extent and duration of overlap between emergent and established leaves was found to differ considerably with cultivar and sowing date. Nitrogen application had little effect on overlap, because differences in crop phenology, e.g. leaf area and nodal length, were relative. However, estimates of raindrop penetration to the base of crop canopies suggested that vertical movement of inoculum is affected by nitrogen application. Crops receiving more nitrogen are denser, and therefore less rainfall reaches the base of the canopy. The interactions between crop and pathogen development are discussed with reference to the implications for predicting disease risk. In particular, cultivar traits that promote disease escape are quantified.

This paper presents a framework for designing the driving functions of an array of radiating elements given a scalar representation of the desired propagating field at a finite number of remote spatial locations. Based on a point source propagation model in a homogeneous media, the relationship between the driving functions and the resulting field leads to a system of linear equations in the frequency domain. A least‐squares solution to the inverse problem is obtained by solving the system of linear equations for the unknown array driving functions. The proposed framework is suitable for designing array driving functions that could be used to generate ‘‘source‐free’’ (homogeneous) solutions to the wave equation. This paper focuses on the use of the proposed technique for calculating array driving functions for generating localized wave energy. Two cases are discussed; one based on a source‐free solution to the wave equation, and the other based on a numerical traveling impulse function. The results are compared to the beam generated by driving the array uniformly with a continuous‐wave (cw) signal.

In this final chapter dealing with the relation between industry and other subsystems of society we shall consider under the broad heading of ‘the community and the polity’ some of those aspects of society not covered in previous chapters. By ‘the community’ we mean a continuous geographical area in which mutually dependent groups act together to satisfy their needs through a common set of organisations and institutions (Anderson and Parker, 1964, p. 102). By ‘the polity’ we mean the sub-system of society oriented to the generation and allocation of power, the relation of the polity and government being conceived as approximately parallel to that of the economy and business.

Social stratification means the division of members of a society into levels or strata that are united by some common attitude or characteristic (Schneider, 1969, p. 148). Stratification is not a sub-system of society in the same sense as the economy, education or the family; rather, it is a generalised aspect of the structure of all complex social systems. Nevertheless, it is possible to examine the relationship between social stratification as it is manifest in industry and in the wider community.

The growth and development of plant pathogens and their hosts generally respond strongly to the temperature of their environment. However, most studies of plant pathology record pathogen/host measurements against physical time (e.g. hours or days) rather than thermal time (e.g. degree-days or degree-hours). This confounds the comparison of epidemiological measurements across experiments and limits the value of the scientific literature.

Sharp eyespot, caused by the soil-borne fungus Rhizoctonia cerealis Van der Hoeven (teleomorph: Ceratobasidium cereale D. Murray & L.L. Burpee), is a common disease of Graminaceae plants including wheat, barley, oats, and rye. The fungus is prevalent throughout the major wheat growing regions of the world and is sometimes associated with pre- and post-emergence damping off and shoot death of seedlings. Accepted for publication 16 June 2003. Published 17 July 2003.

Rain splash is the most important factor in the spread of epidemics of many plant pathogens. Splash height is highly dependent on the kinetic energy of impacting drops. However, direct measurements of rain such as the duration, the amount or the intensity are not related to splash height. We derive a mechanistic model that describes the trajectory of the splashing droplets in terms of the kinetic energy. Experimental data from controlled indoor experiments were used to estimate model parameters and predict the whole distribution of splashes given the kinetic energy of impacting drops. A separate data set from 21 natural rain events was used to verify the model. The maximum splash height was well estimated and the overall splash distribution was well predicted except for lower heights. Three reasons for these differences are discussed: they may be due to (1) ‘secondary’ splashes, (2) the distance between the drop impacting point and the centre of the ‘Precipitation Impact Sensor’ and (3) sampling differences. Different impacting surfaces may have an effect on the model; its robustness is, therefore, discussed. As a first approximation, this model could be used for droplets splashing from leaves within a crop if the structure of the model can be assumed to remain unchanged for different impacting surfaces.

This second part of a two-part series examines total hip arthroplasty in an African-American population. Total hip arthroplasty has revolutionized orthopedic surgery since it began more than two decades ago. The quality and durability of results have enabled patients to pursue a more normal lifestyle, greatly relieved of their pain. Although many studies have reviewed the long-term results of total hip arthroplasty, none have addressed the results in a predominantly African-American population. This study retrospectively reviews the results of total hip arthroplasty in 62 African-American patients. Patients' attitudes toward this surgery, their co-morbid conditions, complications, and results were examined with regard to activity level and acceptance of the procedure.

(1978). FORMYLATION OF ARENES BY α,α-DICHLOROMETHYL METHYL ETHER. AN IMPROVED EXPERIMENTAL PROCEDURE. Organic Preparations and Procedures International: Vol. 10, No. 5, pp. 201-204.

The Systolic Processor with a Reconfigurable Interconnection Network of Transputers (SPRINT) is a sixty-four-processor multiprocessor developed at Lawrence Livermore National Laboratory for experimentally evaluating systolic algorithms and architectures. This paper describes the architecture of the SPRINT and several algorithms which have been executed on it.

The concept of `retrospective bridging' is suggested to describe those occupations in which experience of other kinds of work is relatively frequent. This is complementary to `prospective bridging', indicating the potentialities which one occupation holds for movement to another. Bank workers are shown to have little retrospective mobility by comparison with youth employment and child care officers. Occupation, not sex, is the major factor in determining the number of previous jobs. The past occupations of youth employment and child care officers were mainly those involving contact with clients or customers; banking requires fewer social or personal skills and a varied occupational history is no advantage. The occupationally mobile were more likely to use `most' or `only a few' of their abilities in their work, and the non-mobile to use `some'. Variations in the use of abilities were related to training and scope of present job.

The Systolic Processor with a Reconfigurable Interconnection Network of Transputers (SPRINT) [1] is a sixty-four-element multiprocessor developed at Lawrence Livermore National Laboratory to evaluate systolic algorithms and architectures experimentally. The processors are interconnected in a reconfigurable network which can emulate networks such as the two-dimensional mesh, the triangular mesh, the tree, and the shuffle-exchange network. New systolic algorithms and architectures are described which perform the Radon transform [8] and inverse Radon transform with efficiency arbitrarily close to 100%. High efficiency is possible with any connected network topology, even with low communication bandwidth. The results of the algorithms executed on the SPRINT compare closely with theory.