4,800 research outputs found
Spatial distribution of heavy metal contamination in soils near a primitive e-waste recycling site
No full textHz. Fâtıma’nın Allah Resûlü’ne Mersiye Şiirleri
No full textHz. Fa tıma (ö l. 11/632), babasının nazarında ayrıcalıklı bir könuma sahiptir. Bu bakımdan Araplarda adet ölduğ u u zere Allah Resu lu ’nu n ardından Hz. Fa tıma tarafından mersiye şiirleri ökunması beklenecek bir durumdur. Çalışma, Allah Resu lu ’nu n vefatını mu teakip nu bu vvet evine mensup en yakın bireylerden birinin duyğuları hakkında ipucu vermesi bakımından ö nem arz etmektedir. Ne var ki araştırma könusu şiirlerle ilğili mu stakil çalışmalara rastlanmamaktadır. İ lğili şiirler alandaki böşluğ u döldurmaya katkıda bulunmak amacıyla çalışma könusu yapılmıştır. Hz. Fa tıma’ya ait çalışma könusu beş mersiye şiiri tespit edilmiştir. İ lğili mersiyeler uzun söluklu ğeleneksel Arap şiirleri yerine kısa maktalar halindedir. Maktalarda daha çök şairin yu reğ inde hissettiğ i acı, keder ve duyğu yöğ unluğ u ö n plana çıkmaktadır. Şair acısını hafifletmek ve biraz ölsun rahatlamak amacıyla ö lene kadar durmadan ağ lama arzusundadır. Şair Allah Resu lu ’nu n vefat haberini alan bu tu n Mu slu manların ağ layarak her yerde kendisine eşlik etmelerini istemektedir. Dahası şaire ğö re Allah Resu lu ’nu n hatıralarını taşıyan Uhud dağ ı ve Beytullah da ağ lamalıdır. Şair duyğu yöğ unluğ unu beyitlere yansıtırken elbise yırtma, yu z tırmalama ve yu ksek sesle feryat etme ğibi Ca hiliye adetleri yerine İ sla m inancının beraberinde ğetirdiğ i değ erlere bağ lı kalmaya dikkat etmektedir. Şair bunu yaparken acısını ve duyğu yöğ unluğ unu muhatabın alğısına yaklaştırmak amacıyla eski Arap şiir ğeleneğ inde sıkça rastlanan teşbih, istiare ve mecaz ğibi edebı tasvir ö rneklerine de yer vermektedir.Anahtar Kelimeler: Arap Dili ve Bela ğatı, Allah Resu lu , Hz. Fa tıma, Şiir, Mersiye
Both 50 and 30 Hz continuous theta burst transcranial magnetic stimulation depresses the cerebellum
No full textThe cerebellum is implicated in the pathophysiology of numerous movement disorders, which makes it an attractive target for noninvasive neurostimulation. Continuous theta burst stimulation (cTBS) can induce long lasting plastic changes in human brain; however, the efficacy of different simulation protocols has not been investigated at the cerebellum. Here, we compare a traditional 50-Hz and a modified 30-Hz cTBS protocols at modulating cerebellar activity in healthy subjects. Seventeen healthy adults participated in two testing sessions where they received either 50-Hz (cTBS50) or 30-Hz (cTBS30) cerebellar cTBS. Cerebellar brain inhibition (CBI), a measure of cerebello-thalamocortical pathway strength, and motor evoked potentials (MEP) were measured in the dominant first dorsal interosseous muscle before and after (up to ~ 40 min) cerebellar cTBS. Both cTBS protocols induced cerebellar depression, indicated by significant reductions in CBI (P < 0.001). No differences were found between protocols (cTBS50 and cTBS30) at any time point (P = 0.983). MEP amplitudes were not significantly different following either cTBS protocol (P = 0.130). The findings show cerebellar excitability to be equally depressed by 50-Hz and 30-Hz cTBS in heathy adults and support future work to explore the efficacy of different cerebellar cTBS protocols in movement disorder patients where cerebellar depression could provide therapeutic benefits
Effect of 3 excimer laser ablation frequencies (200 Hz, 500 Hz, 1000 Hz) on the cornea using a 1000 Hz scanning-spot excimer laser.
No full textTo evaluate the possible side effects on human and porcine cadaver eyes induced by excimer laser ablation with 3 ablation frequencies.Augenklinik, Klinikum rechts der Isar, Technische Universitaet Muenchen, Munich, Germany.Central epithelial abrasion was performed on porcine and human donor eyes. Next, the porcine eyes were photoablated (-9.00 diopters) at 1 of 3 frequencies (200 Hz, 500 Hz, or 1000 Hz) using a prototype 1000 Hz excimer laser. The human eyes were ablated at 1000 Hz. The surface of the stroma as well as the structure and ultrastructure of the corneal cells and stroma were examined using light microscopy, transmission electron microscopy, and scanning electron microscopy (SEM). Special attention was given to the detection of potential thermal damage and the evaluation of corneal smoothness.Histopathologic examination showed very low to almost no differences between the 3 repetition rates. In all cases, SEM showed an equally smooth surface.The structural and ultrastructural evaluation of corneas treated with ablation frequencies of 200 Hz, 500 Hz, and 1000 Hz showed no specific side effects associated with the high repetition rates. The ablation quality was comparable in the 3 frequency groups. However, the treatment time was significantly less with a high repetition rate, indicating the clinical potential in refractive surgery of excimer lasers with a repetition rate of 1000 Hz.No author has a financial or proprietary interest in any material or method mentioned. Additional disclosures are found in the footnotes
Monitoring cortical excitability during repetitive transcranial magnetic stimulation in children with ADHD: a single-blind, sham-controlled TMS-EEG study
No full textBackground: Repetitive transcranial magnetic stimulation (rTMS) allows non-invasive stimulation of the human brain. However, no suitable marker has yet been established to monitor the immediate rTMS effects on cortical areas in children.
Objective: TMS-evoked EEG potentials (TEPs) could present a well-suited marker for real-time monitoring. Monitoring is particularly important in children where only few data about rTMS effects and safety are currently available.
Methods: In a single-blind sham-controlled study, twenty-five school-aged children with ADHD received subthreshold 1 Hz-rTMS to the primary motor cortex. The TMS-evoked N100 was measured by 64-channel-EEG pre, during and post rTMS, and compared to sham stimulation as an intraindividual control condition.
Results: TMS-evoked N100 amplitude decreased during 1 Hz-rTMS and, at the group level, reached a stable plateau after approximately 500 pulses. N100 amplitude to supra-threshold single pulses post rTMS confirmed the amplitude reduction in comparison to the pre-rTMS level while sham stimulation had no influence. EEG source analysis indicated that the TMS-evoked N100 change reflected rTMS effects in the stimulated motor cortex. Amplitude changes in TMS-evoked N100 and MEPs (pre versus post 1 Hz-rTMS) correlated significantly, but this correlation was also found for pre versus post sham stimulation.
Conclusion: The TMS-evoked N100 represents a promising candidate marker to monitor rTMS effects on cortical excitability in children with ADHD. TMS-evoked N100 can be employed to monitor real-time effects of TMS for subthreshold intensities. Though TMS-evoked N100 was a more sensitive parameter for rTMS-specific changes than MEPs in our sample, further studies are necessary to demonstrate whether clinical rTMS effects can be predicted from rTMS-induced changes in TMS-evoked N100 amplitude and to clarify the relationship between rTMS-induced changes in TMS-evoked N100 and MEP amplitudes. The TMS-evoked N100 amplitude reduction after 1 Hz-rTMS could either reflect a globally decreased cortical response to the TMS pulse or a specific decrease in inhibition
Half-Sandwich Imido into related complexes of niobium and tantulum - relative of the zirconocene family
No full textThis thesis describes studies directed towards the preparation of half- sandwich niobium and tantalirai compounds containing imido and phosphino-carbene ligands, with particular emphasis on the relationship of such species with bent metallocene complexes of the Group 4 triad. Chapter 1 highlights areas of transition metal chemistry of relevance to the general theme of this thesis, including reviews of metal imido and zirconocene chemistry. Chapter 2 describes the use of silylated anilines for convenient solution syntheses of half-sandwich imido complexes of niobium and tantalum of the type Cp'M(N-2,6-(^i)Pr(_2)-C(_6)H(_3))Cl(_2)(Cp' = Cp, Cp*). In addition, the syntheses and reactivities of mono- and bis-alkyl derivatives (methyl, neopentyl, and benzyl) are presented. The bis-neopentyl complexes CpNb(NR)(CH(_2)CMe(_3))(_2) (R = CMe(_3); 2,6-(^i)Pr(_2)-C(_6)H(_3)), reveal multiple a-agostic interactions which have been primarily studied via an X-ray crystal structure determination and NMR spectroscopy. Thermolysis of Cp*Nb(N-2,6-(^i)Pr(_2)-C(_6)H(_3))(CH(_2)Ph)(_2) in die presence of PMe(_3) affords die benzylidene complex Cp*Nb(N-2,6-(^i)Pr(_2)-C(_6)H(_3))(η(^1)-CHPh)(PMe3) whose X-ray crystal structure has been determined. Chapter 3 describes the preparation of the niobium and tantalum imido complexes Cp'M(N-2,6-(^i)Pr(_2)-C(_6)H(_3))(L)(PMe(_3)) (M = Nb, L = C(_2)H(_4), C(_3)H(_6), CO, Me(_2)C(_2). Ph(_2)C(_2), C(_6)H(_4), PMe(_3); M = Ta, L = C(_2)H(_4), C(_3)H(_6), CO). Single crystal structure determinations on CpNb(N-2,6-(^i)Pr(_2)-C(_6)H(_3))(η(^2)-C(_3)H(_6))(PMe(_3)) and CpNb(N-2,6-(^i)Pr(_2)-C(_6)H(_3))(η(_2)-C(_6)H(_4))(PMe(_3)) have been undertaken and their relationship to Group 4 metallocenes noted. Treatment of Cp*Ta(N-2,6-(^i)Pr(_2)-C(_6)H(_3))(L)(PMe(_3)) (L = C(_2)H(_4),C(_3)H(_6)) with a-olefins was found to lead to displacement of PMe(_3) and the generation of tantallacycle containing species. Chapter 4 compares the reactivity of tantalum imido and phosphino-carbenederivatives of the form Cp*Ta(E)(H)(X)(PMe(_3)) (E = N-2,6-(^i)Pr2-C(_6)H(_3), η(^2)-CHPMe(_2); X = H, I) with a number of a-olefins. Investigations into die mechanism of catalytic oligomerisation of a-olefins by Cp*Ta(η(^2)-CHPMe(_2))(H)(_2)(PMe(_3)) reveal that pathways involving metallacycle intermediates are most probable, whereas Cp*Ta(N-2,6-(^i);Pr(_2)-C(_6)H(_3))(H)(_2)(PMe(_3)) reacts with a-olefins to afford stable tantallacycle complexes. The reactivity of die dihydrido species has been moderated by the preparation of mono- iodide derivatives and their reactivity towards a-olefins studied. Cp*Ta(η(^2)-CHPMe(_2))(H)(I)(PMe(_3)) dimerises ediylene selectively to but-1-ene, while Cp*Ta(N-2,6-(^i)Pr(_2)-C(_6)H(_3))(H)(I)(PMe(_3)) reacts with ethylene to form die stable ethyl species Cp*Ta(N-2,6-(^i)Pr(_2)-C(_6)H(_3))(Et)(I). Furtherrmore, studies investigating a variety of niobium and tantalum imido species as possible catalysts for die oligomerisation and polymerisation of a-olefins under industrially relevant conditions have been undertaken in collaboration with B.P. Chemicals Ltd.. Chapter 5 gives experimental details for chapter 2-4
Técnicas LMI para sistemas com restrições algébricas no estado /
No full textDissertação (Mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico
Powder Technol.
No full textUnder the action of a transverse rotating magnetic field, the fluidization behaviors of the Fe2O3 and CaCO3 particle mixtures were studied and the motion behaviors of the ferromagnetic particles of Fe, Fe2O3, and Fe3O4 were observed. The experiments showed that those ferromagnetic particles, which were placed in a beaker, exhibited four types of motion behaviors (vibrating, forming rotating chains, moving around the wall, and keeping still). The conclusion can be drawn by theoretical analysis of forces and energies that these motions could bring many benefits for fluidization of Geldart Type-C particles. The experiments demonstrated that the fluidization quality of Geldart Type-C particles could be improved by addition of ferromagnetic particles under the external field. It was found that the rotating frequency, field intensity, and volume fraction of magnetic particles were the important factors acting on the fluidization. When field intensity, volume magnetic particle fraction, and rotating frequency were 795.5 A/m, 10% and 5 Hz, respectively, the fluidization was in its optimal condition. The transverse rotating magnetic field affected the incipient fluidization velocity slightly for the mixture of 10% Fe2O3 and 90% CaCO3, but heavily for the mixture of 30% Fe2O3 and 70% CaCO3. (C) 2000 Elsevier Science S.A. All rights reserved.Under the action of a transverse rotating magnetic field, the fluidization behaviors of the Fe2O3 and CaCO3 particle mixtures were studied and the motion behaviors of the ferromagnetic particles of Fe, Fe2O3, and Fe3O4 were observed. The experiments showed that those ferromagnetic particles, which were placed in a beaker, exhibited four types of motion behaviors (vibrating, forming rotating chains, moving around the wall, and keeping still). The conclusion can be drawn by theoretical analysis of forces and energies that these motions could bring many benefits for fluidization of Geldart Type-C particles. The experiments demonstrated that the fluidization quality of Geldart Type-C particles could be improved by addition of ferromagnetic particles under the external field. It was found that the rotating frequency, field intensity, and volume fraction of magnetic particles were the important factors acting on the fluidization. When field intensity, volume magnetic particle fraction, and rotating frequency were 795.5 A/m, 10% and 5 Hz, respectively, the fluidization was in its optimal condition. The transverse rotating magnetic field affected the incipient fluidization velocity slightly for the mixture of 10% Fe2O3 and 90% CaCO3, but heavily for the mixture of 30% Fe2O3 and 70% CaCO3. (C) 2000 Elsevier Science S.A. All rights reserved
Bit Synchronization Methods and Their Performance for HSGPS Receivers
No full textOne problem with the high sensitivity global positioning system (HSGPS) receivers is that the bit edge detection rate decrease dramatically when use the traditional bit synchronization procedure which is called histogram method (HM) in weak signal environment. We propose a hard decision method (HDM) a soft decision (SDM) to enhance bit synchronization efficiency of HSGPS in weak signal situations. Simulation results shown that when the bit detection time is 2 second and the frequency error is 0 and C/N0=19 dB-Hz, an edge detection rate of 85% for HDM can be acquired. when the frequency error is 100 Hz, C/N0= 21 dB-Hz, and other situation remains the same, the edge detection rate is 92%, in both situations SDM is 1 dB better than HDM in bit synchronization sensitivity.(1)http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000289818000047&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=8e1609b174ce4e31116a60747a720701Engineering, Electrical & ElectronicEICPCI-S(ISTP)
An Energy-Efficient 3.7-nV/√ Hz Bridge Readout IC With a Stable Bridge Offset Compensation Scheme
No full textThis paper describes an energy-efficient bridge readout IC (ROIC), which consists of a capacitively coupled instrumentation amplifier (CCIA) that drives a continuous-time delta–sigma modulator (CTM). By exploiting the CCIA’s abilityto block dc common-mode voltages, the bridge’s bias voltage may exceed the ROIC’s supply voltage, allowing these voltages to be independently optimized. Since bridge output is typically much smaller than bridge offset, a digital to analog converter (DAC) is used to compensate this offset before amplification andthus increase the CCIA’s useful dynamic range. Bridge loading is reduced by using a dual-path positive feedback scheme to boost the CCIA’s input impedance. Furthermore, the CCIA’s output is gated to avoid digitizing its output spikes, which would otherwise limit the ROIC’s linearity and stability. The ROIC achieves an input-referred noise density of 3.7 nV/Hz, a noise efficiency factor (NEF) of 5, and a power efficiency factor (PEF) of 44, which both represent the state of the art. A pressure sensing system, built with the ROIC and a differential pressure sensor (AC4010), achieves 10.1-mPa (1) resolution in a 0.5-ms conversion time. The ROIC dissipates about 30% of the system’s power dissipation and contributes about 6% of its noise power. To reduce the sensor’s offset drift, a temperature compensation scheme based on an external reference resistor is used. After a two-point calibration, this scheme reduces bridge offset drift by 80× over a 50 °C range.Accepted Author ManuscriptElectronic InstrumentationMicroelectronic
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