1,116 research outputs found
Evaluation of small area crop estimation techniques using LANDSAT- and ground-derived data
Studies completed in fiscal year 1981 in support of the clustering/classification and preprocessing activities of the Domestic Crops and Land Cover project. The theme throughout the study was the improvement of subanalysis district (usually county level) crop hectarage estimates, as reflected in the following three objectives: (1) to evaluate the current U.S. Department of Agriculture Statistical Reporting Service regression approach to crop area estimation as applied to the problem of obtaining subanalysis district estimates; (2) to develop and test alternative approaches to subanalysis district estimation; and (3) to develop and test preprocessing techniques for use in improving subanalysis district estimates
Evaluation of large area crop estimation techniques using LANDSAT and ground-derived data
The results of the Domestic Crops and Land Cover Classification and Clustering study on large area crop estimation using LANDSAT and ground truth data are reported. The current crop area estimation approach of the Economics and Statistics Service of the U.S. Department of Agriculture was evaluated in terms of the factors that are likely to influence the bias and variance of the estimator. Also, alternative procedures involving replacements for the clustering algorithm, the classifier, or the regression model used in the original U.S. Department of Agriculture procedures were investigated
The attachments of the anteromedial and posterolateral fibre bundles of the anterior cruciate ligament. Part 2: femoral attachment.
Accepted versio
The attachments of the anteromedial and posterolateral fibre bundles of the anterior cruciate ligament: Part 1: tibial attachment.
Accepted versio
Three-Dimensional Venturi Sensor for Measuring Extreme Winds
A three-dimensional (3D) Venturi sensor is being developed as a compact, rugged means of measuring wind vectors having magnitudes of as much as 300 mph (134 m/s). This sensor also incorporates auxiliary sensors for measuring temperature from -40 to +120 F (-40 to +49 C), relative humidity from 0 to 100 percent, and atmospheric pressure from 846 to 1,084 millibar (85 to 108 kPa). Conventional cup-and-vane anemometers are highly susceptible to damage by both high wind forces and debris, due to their moving parts and large profiles. In addition, they exhibit slow recovery times contributing to an inaccurately high average-speed reading. Ultrasonic and hot-wire anemometers overcome some of the disadvantages of the cup and-vane anemometers, but they have other disadvantageous features, including limited dynamic range and susceptibility to errors caused by external acoustic noise and rain. In contrast, the novel 3D Venturi sensor is less vulnerable to wind damage because of its smaller profile and ruggedness. Since the sensor has no moving parts, it provides increased reliability and lower maintenance costs. It has faster response and recovery times to changing wind conditions than traditional systems. In addition, it offers wide dynamic range and is expected to be relatively insensitive to rain and acoustic energy. The Venturi effect in this sensor is achieved by the mirrored double-inflection curve, which is then rotated 360 to create the desired detection surfaces. The curve is optimized to provide a good balance of pressure difference between sensor ports and overall maximum fluid velocity while in the shape. Four posts are used to separate the two shapes, and their size and location were chosen to minimize effects on the pressure measurements. The 3D Venturi sensor has smart software algorithms to map the wind pressure exerted on the surfaces of the design. Using Bernoulli's equation, the speed of the wind is calculated from the differences among the pressure readings at the various ports. The direction of the wind is calculated from the spatial distribution and magnitude of the pressure readings. All of the pressure port sizes and locations have been optimized to minimize measurement errors and to reside in areas demonstrating a stable pressure reading proportional to the velocity range
Segond's fracture: a biomechanical cadaveric study using navigation
Background Segond’s fracture is a well-recognised radiological
sign of an anterior cruciate ligament (ACL) tear.
While previous studies evaluated the role of the anterolateral
ligament (ALL) and complex injuries on rotational
stability of the knee, there are no studies on the biomechanical
effect of Segond’s fracture in an ACL deficient
knee. The aim of this study was to evaluate the effect of a
Segond’s fracture on knee rotation stability as evaluated by
a navigation system in an ACL deficient knee.
Materials and methods Three different conditions were
tested on seven knee specimens: intact knee, ACL deficient
knee and ACL deficient knee with Segond’s fracture. Static
and dynamic measurements of anterior tibial translation
(ATT) and axial tibial rotation (ATR) were recorded by the
navigation system (2.2 OrthoPilot ACL navigation system
B. Braun Aesculap, Tuttlingen, Germany).
Results Static measurements at 30 showed that the mean
ATT at 30 of knee flexion was 5.1 ± 2.7 mm in the ACL
intact condition, 14.3 ± 3.1 mm after ACL cut
(P = 0.005), and 15.2 ± 3.6 mm after Segond’s fracture
(P = 0.08). The mean ATR at 30 of knee flexion was
20.7 ± 4.8 in the ACL intact condition, 26.9 ± 4.1 in
the ACL deficient knee (P[0.05) and 30.9 ± 3.8 after
Segond’s fracture (P = 0.005). Dynamic measurements
during the pivot-shift showed that the mean ATT was
7.2 ± 2.7 mm in the intact knee, 9.1 ± 3.3 mm in the
ACL deficient knee(P = 0.04) and 9.7 ± 4.3 mm in the
ACL deficient knee with Segond’s fracture (P = 0.07).
The mean ATR was 9.6 ± 1.8 in the intact knee,
12.3 ± 2.3 in the ACL deficient knee (P[0.05) and
19.1 ± 3.1 in the ACL deficient knee with Segond’s
lesion (P = 0.016).
Conclusion An isolated lesion of the ACL only affects
ATT during static and dynamic measurements, while the
addition of Segond’s fracture has a significant effect on
ATR in both static and dynamic execution of the pivot-shift
test, as evaluated with the aid of navigation
Change management: The case of the elite sport performance team
The effective and efficient implementation of change is often required for both successful performance and management survival across a host of contemporary domains. However, although of major theoretical and practical significance, research to date has overlooked the application of change management (hereafter CM) knowledge to the elite sport performance team environment. Considering that the success of ‘off-field’ sports businesses are largely dependent on the performances of their ‘on-field’ team, this article explores the application of current CM theorizing to this specific setting and the challenges facing its utility. Accordingly, we identify the need and importance of developing theory specific to this area, with practical application in both sport and business, through examination of current knowledge and identification of the domain's unique, dynamic and contested properties. Markers of successful change are then suggested to guide initial enquiry before the article concludes with proposed lines of research which may act to provide a valid and comprehensive theoretical account of CM to optimize the research and practice of those working in the field
The hind- and midfoot alignment analyzed after a medializing calcaneal osteotomy using a 3D weight bearing CT
Changes in knee kinematics reflect the articular geometry after arthroplasty
We hypothesized changes in rotations and translations after TKA with a fixed-bearing anterior cruciate ligament (ACL)-sacrificing but posterior cruciate ligament (PCL)-retaining design with equal-sized, circular femoral condyles would reflect the changes of articular geometry. Using 8 cadaveric knees, we compared the kinematics of normal knees and TKA in a standardized navigated position with defined loads. The quadriceps was tensed and moments and drawer forces applied during knee flexion-extension while recording the kinematics with the navigation system. TKA caused loss of the screw-home; the flexed tibia remained at the externally rotated position of normal full knee extension with considerably increased external rotation from 63° to 11° extension. The range of internal-external rotation was shifted externally from 30° to 20° extension. There was a small tibial posterior translation from 40° to 90° flexion. The varus-valgus alignment and laxity did not change after TKA. Thus, navigated TKA provided good coronal plane alignment but still lost some aspects of physiologic motion. The loss of tibial screw-home was related to the symmetric femoral condyles, but the posterior translation in flexion was opposite the expected change after TKA with the PCL intact and the ACL excised. Thus, the data confirmed our hypothesis for rotations but not for translations. It is not known whether the standard navigated position provides the best match to physiologic kinematics
Performing innocence: violence and the nation in Ian McEwan’s Saturday and Sunjeev Sahota’s Ours Are the Streets
British normative society and post-9/11 fiction borrow from the discourse of American exceptionalism (including the fall from innocence to experience, the desire to create or preserve a better world, a ‘Messianic consciousness’ reflecting the arrogance of virtue, the development of narratives of heroism and goodness tied to nation-building, and the use of the above to justify ‘exemptionalism’) to expose and query the entitlement of those within the narrative home of Britishness and the outsider-status of those used to define its borders. This article discusses Ian McEwan’s Saturday and Sunjeev Sahota’s Ours Are the Streets, arguing that they illustrate a turning point in Britain’s imagination of itself as a nation in a struggle over Britishness which is predicated on notions of violence and innocence. Since 9/11 the debate about Britishness has used innocence as a constitutive inside of the nation and direct violence as an exclusionary characteristic. McEwan satirizes this rhetoric of innocence whereas Sahota challenges it. Both novels illustrate how post-9/11 British fiction deals with politics as war, placing violence at the heart of society. McEwan parodies the point of view of British normative society by allowing his main character to justify his privileged position under the guise of arguing for the current social and international status quo. Sahota charts the journey of those who are caught between the rejection of unjust social structures and the desire to fit within them, depicting his protagonist’s misguided attempt to redefine the British nation through terrorism. Violence and exceptionalism are central to both novels, which portray a turn in the imagining of Britain. The events of 9/11 can therefore be seen not just as a historical turning point but as a turn in Britain’s imagination of itself
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