2,360 research outputs found
A universal six-joint robot controller
A general purpose six-axis robotic manipulator controller was designed and implemented to serve as a research tool for the investigation of the practical and theoretical aspects of various control strategies in robotics. A 80286-based Intel System 310 running the Xenix operating servo software as well as the higher level software (e.g., kinematics and path planning) were employed. A Multibus compatible interface board was designed and constructed to handle I/O signals from the robot manipulator's joint motors. From the design point of view, the universal controller is capable of driving robot manipulators equipped with D.C. joint motors and position optical encoders. To test its functionality, the controller is connected to the joint motor D.C. power amplifier of a PUMA 560 arm bypassing completely the manufacturer-supplied Unimation controller. A controller algorithm consisting of local PD control laws was written and installed into the Xenix operating system. Additional software drivers were implemented to allow application programs access to the interface board. All software was written in the C language
Parallel processing architecture for computing inverse differential kinematic equations of the PUMA arm
In advanced robot control problems, on-line computation of inverse Jacobian solution is frequently required. Parallel processing architecture is an effective way to reduce computation time. A parallel processing architecture is developed for the inverse Jacobian (inverse differential kinematic equation) of the PUMA arm. The proposed pipeline/parallel algorithm can be inplemented on an IC chip using systolic linear arrays. This implementation requires 27 processing cells and 25 time units. Computation time is thus significantly reduced
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Neurotrophic keratitis after micropulse transscleral diode laser cyclophotocoagulation.
PurposeTo report two cases of neurotrophic keratitis (NK) after micropulse transscleral cyclophotocoagulation (MP-TCP).ObservationsTwo patients with predisposing factors for decreased corneal sensation developed NK 1 month after MP-TCP. Both patients did not heal with initial treatment with topical antibiotic and preservative free artificial tears. One patient required use of a bandage contact lens and the other patient required tarsorrhaphy. Both eyes experienced recurrence of NK.Conclusions and importanceNK can be triggered after MP-TCP in patients with underlying predisposing factors for decreased corneal sensation. This uncommon but vision-threatening complication should be discussed preoperatively with high-risk patients as a possible adverse event after MP-TCP and followed closely postoperatively
A Hemoglobin-Based Multifunctional Therapeutic: Polynitroxylated Pegylated Hemoglobin
Polynitroxylated pegylated hemoglobin (PNPH) as a multifunctional therapeutic takes advantage of the ability of hemoglobin (Hb) to transport oxygen, the antioxidative stress activities from the redox coupling of nitroxide and heme iron, and the hypercolloid properties of pegylation. The published preclinical data demonstrating that PNPH acts as a neurovascular protective multifunctional therapeutic in an animal model simulating prehospital resuscitation of traumatic brain injury (TBI) with hemorrhagic shock (HS) are reviewed. Preliminary results on the potential utility of PNPH for neurovascular protection in thrombolytic stroke therapy and for correction of vascular dysfunction through transfusion in sickle-cell disease (SCD) are also discussed. We hypothesize that with PNPH, Hb has more than been tamed--it has become a therapeutic and not just a nontoxic extracellular oxygen carrier--and that successful PNPH development as a multifunctional therapeutic that protects the neurovasculature and reduces oxidative stress may represent a paradigm shift in transfusion and critical care medicine, which may meet a number of unmet medical needs resulting from oxidative stress and inadequate blood flow, such as HS, TBI, SCD, and stroke
HUBBLE SPACE TELESCOPE OBSERVATIONS AND GEOMETRIC MODELS OF COMPACT MULTIPOLAR PLANETARY NEBULAE
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Transformations of Progesterone by Subcellular Fractions of Human Skin
Homogenates of human skin metabolize progesterone-4-14C to the same products as whole skin. Studies with subcellular fractions obtained by differential centrifugation indicate the presence in skin of a membrane-bound 5α-reductase and a soluble 20α-hydroxysteroid dehydrogenase (20α-HSD), both of which utilize TPNH as cofactor. The 20α-HSD has a pH optimum of 6.2 and a Km of approximately 7 μM. Unlike placental preparations, the 105,000 × g supernatant fraction prepared from human skin has more 20α-HSD than 17β-hydroxy-steroid dehydrogenase activity. This soluble skin enzyme acting on steroid hormones is distinct from previously reported particulate enzymes
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A Novel Survey Tool to Quantify the Degree and Duration of STEMI Regionalization Across California.
IntroductionCalifornia has been a global leader in regionalization efforts for time-critical medical conditions. A total of 33 local emergency medical service agencies (LEMSAs) exist, providing an organized EMS framework across the state for almost 40 years. We sought to develop a survey tool to quantify the degree and duration of ST-elevation myocardial infarction (STEMI) regionalization over the last decade in California.MethodsThe project started with the development of an 8-question survey tool via a multi-disciplinary expert consensus process. Next, the survey tool was distributed at the annual meeting of administrators and medical directors of California LEMSAs to get responses valid through December, 2014. The first scoring approach was the Total Regionalization Score (TRS) and used answers from all 8 questions. The second approach was called the Core Score, and it focused on only 4 survey questions by assuming that the designation of STEMI Receiving Centers must have occurred at the beginning of any LEMSA's regionalization effort. Scores were ranked and grouped into tertiles.ResultsAll 33 LEMSAs in California participated in this survey. The TRS ranged from 15 to 162. The Core Score range was much narrower, from 2 to 30. In comparing TRS and Core Score rankings, the top-tertiles were quite similar. More rank variation occurred between mid- and low-tertiles.ConclusionThis study evaluated the degree and duration of STEMI network regionalization from 2004 to 2014 in California, and ranked 33 LEMSAs into tertiles based upon their TRS and their Core Score. Successful application of the 8-item survey and ranking strategies across California suggests that this approach can be used to assess regionalization in other states or countries around the world
New modelling technique for aperiodic-sampling linear systems
A general input-output modelling technique for aperiodic-sampling linear
systems has been developed. The procedure describes the dynamics of the system
and includes the sequence of sampling periods among the variables to be
handled. Some restrictive conditions on the sampling sequence are imposed in
order to guarantee the validity of the model. The particularization to the
periodic case represents an alternative to the classic methods of
discretization of continuous systems without using the Z-transform. This kind
of representation can be used largely for identification and control purposes.Comment: 19 pages, 0 figure
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