On-orbit assembly using superquadric potential fields

The autonomous on-orbit assembly of a large space structure is presented using a method based on superquadric artificial potential fields. The final configuration of the elements which form the structure is represented as the minimum of some attractive potential field. Each element of the structure is then considered as presenting an obstacle to the others using a superquadric potential field attached to the body axes of the element. A controller is developed which ensures that the global potential field decreases monotonically during the assembly process. An error quaternion representation is used to define both the attractive and superquadric obstacle potentials allowing the final configuration of the elements to be defined through both relative position and orientation. Through the use of superquadric potentials, a wide range of geometric objects can be represented using a common formalism, while collision avoidance can make use of both translational and rotation maneuvers to reduce total maneuver cost for the assembly process

Remifentanil vs dexmedetomidine for severely preeclamptic parturients scheduled for cesarean section under general anesthesia: A randomized controlled trial

AbstractObjectivesTo compare the effect of remifentanil vs dexmedetomidine on hemodynamic response of noxious stimuli and neonatal outcome in preeclamptic parturient underwent C.S. under G.A.MethodsThis blinded, prospective, randomized trial included 50 preeclamptic parturients underwent C.S under G.A., randomized into two equal groups [25 patients each]: group R [remifentanil]: received 1μg/kg loading and 0.05μg/kg/min infusion doses and group D [dexmedetomidine] received 1/kg loading and 0.2μg/kg/h infusion doses. Maternal MAP and HR were assessed before medication (T0), just after induction of GA (TI), just after intubation (TT), two minutes after intubation (TT2), just after skin incision (TS), two minutes after skin incision (TS2), just after delivery of the baby (TD), and at the end of operation (TE). Time between induction and fetal delivery (I-D interval), time between incision of the uterus and delivery (U-D interval), and time between stop of the infusion of the tested drugs and delivery (D-D interval) were recorded. Neonatal Apgar score was recorded at 1 and 5min and the need for resuscitative measures.ResultsMaternal MAP and HR in group R were statistically lower at (TI), (TT), (TT2), (TS) and (TS2). Neonatal Apgar score was statistically lower in group R with higher incidence for tactile stimulation.ConclusionBoth remifentanil and dexmedetomidine were effective on blunting the pressor response to noxious stimuli in severely preeclamptic parturients. While remifentanil was marginally more effective in suppressing the pressor response, dexmedetomidine was safer for the neonates

Cordylobia Anthropophaga: Furuncular Myiasis in a Family of 3

Cutaneous myiasis due to infestation by the larva of Cordylobia anthropophaga is an underreported occurrence. Awareness is important to avoid misrecognition or delay in diagnosis. We describe a family of three with cutaneous myiasis caused by the African Tumbu fly (Cordylobia anthropophaga) presenting as multiple abscesses, demonstrating the need for a detailed travel history in such a presentation. The nature of the lesions, the life cycle and treatment modalities are discussed. Cutaneous myiasis requires an awareness of its clinical features specifically in patients presenting with furuncular skin lesions who live within endemic areas or persons returning from such areas. Diagnosis is mainly clinical and lesions heal well after the extraction of the larvae. Good personal hygiene including ironing of clothes is crucial in controlling C. anthropophaga infestation.Key Words: Myiasis, Furuncular, Cordylobia anthropophag

Comparison of Three Techniques for Arthrocentesis of the Carpal Joint in Dromedary Camels: A Prospective Study

The aim of this prospective study was to determine the appropriate approaches for arthrocentesis of the carpal joint in dromedary camels and to compare between these approaches with regard to their success rate, feasibility, accuracy and ease of performance. Twenty-two cadaveric camel forelimbs obtained from 11 camel cadavers, and 4 living camels (6 joints) underwent arthrocentesis for therapeutic and diagnostic purposes, were used in this study. For studying gross anatomy of the suggested approaches, 4 forelimbs were used. For CT anatomy 3 forelimbs (one/each technique) were scanned before and after injection of iodinated contrast medium. For in-vitro evaluation of the techniques 15 forelimbs were used (5/each technique). To test the ease of performance in the living camels, arthrocentesis of 6 joints in 4 camels was performed by a single operator while the animal sited in kneeling position (3 camels) and standing position (one camel). Based on the results, there were three feasible approaches for arthrocentesis of carpal joint in camel, the dorso-medial, dorso-lateral, and the lateral approaches. The dorso-medial approach was easily performed and more accurate than the other approaches. The dorso-medial approach was successful with accuracy index of 100% after the first attempts, whilst the dorso-lateral and the lateral approaches have lower rates of success. The procedure was well tolerated in all camels

The use of beta-carotene as environmentally safe inhibitor for Cu-Al-Ni alloyscorrosion in sulfide polluted chloride solutions

The stability of Cu-Al-Ni alloys used in the manufacture of NaCl in Egypt was investigated in sulfide polluted chloride solutions. Three different alloys, namely, Cu-10Al-5Ni, Cu-10Al-10Ni and Cu-10Al-45Niwereinvestigatedinchloride containingsulfide-ions using different electrochemical techniques including polarization and electrochemical impedance spectroscopy. The presence of sulfide ions in the chloride solution accelerates thecorrosion of Cu-Al-Ni alloys,whereas the increase of the nickel content in the alloy improves its corrosion resistance.?-carotene as eco-friendly corrosion inhibitor was used to protect the Cu-10Al-Ni alloys from corrosion in presence of sulfide ions. The corrosion inhibition efficiency reached >95% at 50 ppm of ?-carotene. The alloy surface was investigated by the scanning electron microscope and the surface constituents were analyzed by EDAX. Keywords: Corrosion; chloride, Cu-Ni alloys; EIS; sulfide pollution

Constructing an Instrument for Measuring the Selective Visual Attention of Basic-Stage Students in Gaza and Verifying its Psychometric Characteristics

The research aims at constructing an instrument for measuring the selective visual attention of basic education students in Gaza, and verifying its validity and reliability. The research sample consisted of 200   grade ten students in Khan Younis (for the academic year, 2018 -2019). The evidence of constructive validity and the factorial validity of the instrument were  investigated. Results of the predictive factorial analysis showed that the three tasks of the instrument  covered a single  potential factor  namely selective visual attention. All slides of the selective visual attention tasks have achieved statistically significant correlations with the overall scores of the instrument.  The content of the slides was also validated in relation to the instrument. The instrument reliability was also checked with the alpha coefficient for the final form of the instrument as a whole (0,962), and the split–half  reliability coefficients ranged from (0.770 – 0.907). The final form of the instrument  showed three major functions

Towards Internet QoS Provisioning Based on Generic Distributed QoS Adaptive Routing Engine

Increasing efficiency and quality demands of modern Internet technologies drive today’s network engineers to seek to provide quality of service (QoS). Internet QoS provisioning gives rise to several challenging issues. This paper introduces a generic distributed QoS adaptive routing engine (DQARE) architecture based on OSPFxQoS. The innovation of the proposed work in this paper is its undependability on the used QoS architectures and, moreover, splitting of the control strategy from data forwarding mechanisms, so we guarantee a set of absolute stable mechanisms on top of which Internet QoS can be built. DQARE architecture is furnished with three relevant traffic control schemes, namely, service differentiation, QoS routing, and traffic engineering. The main objective of this paper is to (i) provide a general configuration guideline for service differentiation, (ii) formalize the theoretical properties of different QoS routing algorithms and then introduce a QoS routing algorithm (QOPRA) based on dynamic programming technique, and (iii) propose QoS multipath forwarding (QMPF) model for paths diversity exploitation. NS2-based simulations proved the DQARE superiority in terms of delay, packet delivery ratio, throughput, and control overhead. Moreover, extensive simulations are used to compare the proposed QOPRA algorithm and QMPF model with their counterparts in the literature

Specificity of the Acute Tryptophan and Tyrosine Plus Phenylalanine Depletion and Loading Tests Part II: Normalisation of the Tryptophan and the Tyrosine Plus Phenylalanine to Competing Amino Acid Ratios in a New Control Formulation

Current formulations for acute tryptophan (Trp) or tyrosine (Tyr) plus phenylalanine (Phe) depletion and loading cause undesirable decreases in ratios of Trp or Tyr + Phe to competing amino acids (CAA), thus undermining the specificities of these tests. Branched-chain amino acids (BCAA) cause these unintended decreases, and lowering their content in a new balanced control formulation in the present study led to normalization of all ratios. Four groups (n = 12 each) of adults each received one of four 50 g control formulations, with 0% (traditional), 20%, 30%, or 40% less of the BCAA. The free and total [Trp]/[CAA] and [Phe + Tyr]/[BCAA + Trp] ratios all decreased significantly during the first 5 h following the traditional formulation, but were fully normalized by the formulation containing 40% less of the BCAA. We recommend the latter as a balanced control formulation and propose adjustments in the depletion and loading formulations to enhance their specificities for 5-HT and the catecholamines

Stability of Some Copper Ternary Alloys in Chloride Solutions Polluted by Sulfide Ions

The electrochemical performance of three copper alloys was investigated in simulated marine solution polluted by sulfide ions. Polarization techniques and electrochemical impedance spectroscopy, EIS, were used. Surface examination and morphological studies were employed. The results showed that the Cu-10Ni-10Zn alloy is more stable than the other two alloys. The alloy surface was covered by a barrier layer protecting it from corrosion. The thickness and resistance of the barrier layer formed on the Cu-10Ni-10Zn alloy increases with the increase of the immersion time. The mechanism of the corrosion process and the barrier film formation was discussed.  A comparison was made between the electrochemical stability of the three alloys in sulfide polluted chloride solution. The incorporation of Ni in the Cu2O barrier film leads to its stabilization and the stability is enhanced by the presence of Zn. The results leads to the recommendation of the Cu-10Ni-10Zn alloy for applications in sulfide polluted marine environments. Keywords:  Copper alloys, EIS, Polarization, SEM, Passive Films