Electron Microprobe Chemical Dating of Uraninite as a Reconnaissance Tool for Leucogranite Geochronology

We suggest that electron microprobe techniques may be employed to date Tertiary samples of uraninite (UO~2~), which can contain very high concentrations of radiogenic Pb after only a few million of years of U and Th decay. Although uraninite is regarded as a rare accessory mineral, it is relatively abundant in leucogranitic rocks such as those found in the Himalayan orogen. We apply the U-Th-total Pb electron microprobe chemical dating method to a uraninite crystal from a ca. 18.3 Ma dike of the Mugu granite from the Upper Mustang region of central Nepal. With this technique, we calculate a mean chemical date that is consistent with isotope-dilution thermal ionization mass spectrometry (ID-TIMS) U-Pb dates obtained from seven other uraninite grains and a monazite crystal from the same sample. Electron microprobe chemical dating yields results that typically will be an order of magnitude less precise than conventional dates: in the specific case of the Mugu granite, single point chemical dates each have ca. 1.5 Ma 2[sigma] (95%) confidence level uncertainties. However, the mean chemical date of 15 point analyses of the crystal we study has a 2SE (2 standard error) uncertainty of ca. 400 ka, comparable to uncertainties obtained with ID-TIMS. These results show that electron microprobe chemical dating of uraninite has substantial promise as a reconnaissance tool for the geochronology of young granitic rocks. The electron microprobe work also reveals substantial chemical complexity within uraninite that must be taken into account. The analyzed crystal displays a texturally and chemically distinctive core and rim that suggests episodic growth. Concentration gradients in U, Th, and Y across the boundary imply diffusive modification. We estimate the diffusivity of U, Th, and Y in uraninite at ca. 700 °C to be > 10-7 cm2 s-1. In contrast, Pb shows no distinctive concentration gradient across the core-rim boundary, implying that Pb has a much higher diffusivity in uraninite than U, Th, or Y. We estimate that Pb loss of as much as ca. 8.9% has occurred in the uraninite grains we analyzed by ID-TIMS

Ab initio description of nonlinear dynamics of coupled microdisk resonators with application to self-trapping dynamics

Ab initio approach is used to describe the time evolution of the amplitudes of whispering gallery modes in a system of coupled microdisk resonators with Kerr nonlinearity. It is shown that this system demonstrates a transition between Josephson-like nonlinear oscillations and self-trapping behavior. Manifestation of this transition in the dynamics of radiative losses is studied.Comment: 10 pages, 5 figures, accepted for publication in Phys. Rev.

EAP-CRA for WiMAX, WLAN and 4G LTE Interoperability

Today we are moving into a “post-PC” world! Not many people sit in front of custom built PCs to do their businesses any more. Hand held devices such as iPod Touch, iPhone, Galaxy S3, iPad, Galaxy Tab, Airbook, Notepad etc. are bringing in a new paradigm as to how people use and communicate information. These devices can be thought as a theoretical “black-box”. They are for people who want to use it without wanting to know how they work. Such devices have third generation user interfaces – multi touch, physics and gestures (MPG). They need updates, but the user is not worried of how and where the files are stored. When a new application is installed, the user sees the icon and starts using it. The user is not interested in, what files were installed or where it was installed – there is no file management. The post-PC approach to dealing with software is that it’s discovered on an app store, downloaded with a single touch and deleted with another touch. Updates all come at once from the app store and it all happens behind the scene with minimal user involvement. All this is happening and adopted rapidly because people are able to do a number of things without being restricted to one place. They can download apps, watch movies, listen to news, browse the web etc. while on the move.Griffith Sciences, School of Information and Communication TechnologyFull Tex

PT-Symmetric Talbot Effects

We show that complex PT-symmetric photonic lattices can lead to a new class of self-imaging Talbot effects. For this to occur, we find that the input field pattern, has to respect specific periodicities which are dictated by the symmetries of the system. While at the spontaneous PT-symmetry breaking point, the image revivals occur at Talbot lengths governed by the characteristics of the passive lattice, at the exact phase it depends on the gain and loss parameter thus allowing one to control the imaging process.Comment: 5 pages, 3 figure

Exceptional point based lattice gyroscopes

Ring laser gyroscopes (RLGs) based on non-Hermitian exceptional points (EPs) have garnered much recent interest due to their exceptional sensitivity. Such gyroscopes typically consist of two-ring laser resonators, one with loss and one with an equal amount of optical gain. The coupling strength between these ring resonators is a key parameter determining the sensitivity of EP-based RLGs. Here we explore how the exceptional sensitivity demonstrated in this coupled dimer may be further enhanced by adding more dimers in an array. Specifically, we propose two types of ring laser gyroscope lattice arrays, each composed of N coupled dimers arrayed serially or concentrically with periodic boundary conditions, that guide counter-propagating photons in a rotating frame. Using coupled mode theory, we show that these lattice gyroscopes exhibit an enhanced effective coupling rate between the gain and loss resonators at the EP, thereby producing greater sensitivity to the angular rotation rate than their constituent dimers. This work paves the way toward EP-based RLGs with the necessary sensitivity for GPS-free navigation

Efficacy of a modified bier�s block in patients undergoing upper limb bone surgery

Background: Intravenous regional block, called the Bier's block, refers to an analgesic technique applied for soft tissue surgeries and closed bone manipulations of the limbs. There are a number of complications in traditional method of block, including pain in tourniquet site, immediate return of pain after tourniquet deflation, wound hemostasis and some others. Objectives: The aim of this study was to assess the outcomes and complications of our new method of blockage. Patients and Methods: In this experimental study, twenty-five patients undergoing hand surgery were prospectively studied. Induced anesthesia was a modifcation of the Bier's block with two concurrent changes including insertion of the intravenous cannula at the antecubital region rather than distal and the proximal anesthetic direction by an elastic band wrapped tightly around the proximal forearm distal to the cannulation site. The pain relief was measured by the verbal descriptive scale at intervals after block, during the operation, after deflation of the tourniquet and one hour after the operation. Results: This study showed the presence of analgesia at surgical and tourniquet sites during the operation in 96 of patients, as well as considerable pain relief at surgical site during one hour after deflation of the tourniquet. Conclusions: The study indicated advantages of this modified Bier's block compared to the traditional one including ability to perform surgery on upper limb bones and considerable pain relief at surgical and tourniquet sites during the operation until one hour thereafter. © 2015, Iranian Society of Regional Anesthesia and Pain Medicine (ISRAPM)

Numerical investigation of the aerodynamic performance for a Wells-type turbine in a wave energy converter

Ocean waves constitute an extensive energy resource, whose extraction has been the subject of intense research activity in the last three decades. Among the different variants of Wave Energy Converters, the principle of the Oscillating Water Col- umn (OWC) is one of the most promising ones. An OWC comprises two key elements: a collector chamber, which transfers the wave oscillations’ energy to the air within the chamber by back and forth displacement, and a power take off system, which converts the pneumatic power into electricity or some other usable form. The Wells turbine is a self-rectifying air turbine, a suitable solution for energy extraction from reciprocating air flow in an OWC. In the present work, the steady state, inviscid flow in the Wells turbine is investigated by numerical simulations. The relatively novel Virtual Multiple Reference Frame (VMRF) technique is used to account for the rotary motion of the turbine, and the overall performance is compared with results in the literature

Numerical investigation of the aerodynamic performance for a wells-type turbine in a wave energy converter

Ocean waves constitute an extensive energy resource, whose extraction has been the subject of intense research activity in the last three decades. Among the different variants of Wave Energy Converters, the principle of the Oscillating Water Column (OWC) is one of the most promising ones. An OWC comprises two key elements: A collector chamber, which transfers the wave oscillations' energy to the air within the chamber by back and forth displacement, and a power take off system, which converts the pneumatic power into electricity or some other usable form. The Wells turbine is a self-rectifying air turbine, a suitable solution for energy extraction from reciprocating air flow in an OWC. In the present work, the steady state, inviscid flow in the Wells turbine is investigated by numerical simulations. The relatively novel Virtual Multiple Reference Frame (VMRF) technique is used to account for the rotary motion of the turbine, and the overall performance is compared with results in the literature

PT-symmetric coupler with a coupling defect : soliton interaction with exceptional point

We study the interaction of a soliton in a parity-time (PT) symmetric coupler which has local perturbation of the coupling constant. This defect does not change the PT-symmetry of the system, but locally can achieve the exceptional point. We found that the symmetric solitons after interaction with the defect either transform into breathers or blow up. The dynamics of antisymmetric solitons are more complex, showing domains of successive broadening of the beam and of the beam splitting in two outward propagating solitons, in addition to the single breather generation and blowup. All the effects are preserved when the coupling strength in the center of the defect deviates from the exceptional point. If the coupling is strong enough, the only observable outcome of the soliton-defect interaction is the generation of the breather.The work was supported by the Program of Introducing Talents of Discipline to Universities under Grant No. B12024. Y. V. B. and V. V. K. were supported by FCT (Portugal) grants PEst-C/FIS/UI0607/2013, PEst-OE/FIS/UI0618/2011, PTDC/FIS-OPT/1918/2012. C. H. and G. X. H. were supported by the NSF-China grants 11105052 and 11174080