Active and Passive Quantum Erasers for Neutral Kaons

Quantum marking and quantum erasure are discussed for the neutral kaon system. Contrary to other two-level systems, strangeness and lifetime of a neutral kaon state can be alternatively measured via an "active" or a "passive" procedure. This offers new quantum erasure possibilities. In particular, the operation of a quantum eraser in the "delayed choice" mode is clearly illustrated.Comment: 17 pages, LaTeX, 1 figure, references added, accepted by Phys. Rev.

Considerations on Super Poincare Algebras and their Extensions to Simple Superalgebras

We consider simple superalgebras which are a supersymmetric extension of \fspin(s,t) in the cases where the number of odd generators does not exceed 64. All of them contain a super Poincar\'e algebra as a contraction and another as a subalgebra. Because of the contraction property, some of these algebras can be interpreted as de Sitter or anti de Sitter superalgebras. However, the number of odd generators present in the contraction is not always minimal due to the different splitting properties of the spinor representations under a subalgebra. We consider the general case, with arbitrary dimension and signature, and examine in detail particular examples with physical implications in dimensions $d=10$ and $d=4$.Comment: 16 pages, AMS-LaTeX. Version to appear in the Reviews in Mathematical Physic

Evolution of kinklike fluctuations associated with ion pickup within reconnection outflows in the Earth's magnetotail

Magnetic reconnection (MR) in Earth's magnetotail is usually followed by a systemwide redistribution of explosively released kinetic and thermal energy. Recently, multispacecraft observations from the THEMIS mission were used to study localized explosions associated with MR in the magnetotail so as to understand subsequent Earthward propagation of MR outbursts during substorms. Here we investigate plasma and magnetic field fluctuations/structures associated with MR exhaust and ion-ion kink mode instability during a well documented MR event. Generation, evolution and fading of kinklike oscillations are followed over a distance of 70 000 km from the reconnection site in the midmagnetotail to the more dipolar region near the Earth. We have found that the kink oscillations driven by different ion populations within the outflow region can be at least 25 000 km from the reconnection site.Comment: 11 pages, 4 figure

The space physics environment data analysis system (SPEDAS)

With the advent of the Heliophysics/Geospace System Observatory (H/GSO), a complement of multi-spacecraft missions and ground-based observatories to study the space environment, data retrieval, analysis, and visualization of space physics data can be daunting. The Space Physics Environment Data Analysis System (SPEDAS), a grass-roots software development platform (www.spedas.org), is now officially supported by NASA Heliophysics as part of its data environment infrastructure. It serves more than a dozen space missions and ground observatories and can integrate the full complement of past and upcoming space physics missions with minimal resources, following clear, simple, and well-proven guidelines. Free, modular and configurable to the needs of individual missions, it works in both command-line (ideal for experienced users) and Graphical User Interface (GUI) mode (reducing the learning curve for first-time users). Both options have “crib-sheets,” user-command sequences in ASCII format that can facilitate record-and-repeat actions, especially for complex operations and plotting. Crib-sheets enhance scientific interactions, as users can move rapidly and accurately from exchanges of technical information on data processing to efficient discussions regarding data interpretation and science. SPEDAS can readily query and ingest all International Solar Terrestrial Physics (ISTP)-compatible products from the Space Physics Data Facility (SPDF), enabling access to a vast collection of historic and current mission data. The planned incorporation of Heliophysics Application Programmer’s Interface (HAPI) standards will facilitate data ingestion from distributed datasets that adhere to these standards. Although SPEDAS is currently Interactive Data Language (IDL)-based (and interfaces to Java-based tools such as Autoplot), efforts are under-way to expand it further to work with python (first as an interface tool and potentially even receiving an under-the-hood replacement). We review the SPEDAS development history, goals, and current implementation. We explain its “modes of use” with examples geared for users and outline its technical implementation and requirements with software developers in mind. We also describe SPEDAS personnel and software management, interfaces with other organizations, resources and support structure available to the community, and future development plans.Published versio

Characterization of a new laboratory ceramic product from industrial by-products as raw materials and caustic magnesia as additive

Στην εργασία αυτή παρουσιάζεται ένα νέο κεραμικό προϊόν που παράχθηκε από μίξη καυστικής μαγνησίας, που παρασκευάστηκε εργαστηριακά από υψηλής καθαρότητας μαγνησίτη, φυσικού πηλού καθώς και τέφρας πυθμένα και ερυθράς ιλύος, προϊόντα γνωστά για τις δυσμενείς περιβαλλοντικές επιπτώσεις τους. Έπειτα από δοκιμή ποικίλων συνταγών, συμπεράναμε ότι προσθήκη 5% καυστικής μαγνησίας στο κεραμικό προϊόν βελτιώνει τις μηχανικές επιδόσεις του. Αυτό αποδίδεται στο γεγονός ότι το περίκλαστο της καυστικής μαγνησίας σχηματίζει «λαιμούς», οι οποίοι ισχυροποιούν τους δεσμούς στη μικροδομή του κεραμικού, σε συνδυασμό με τον ταυτόχρονο σχηματισμό μικρών ποσοτήτων άμορφου υλικού και την ομοιογενή κατανομή των πόρων, που δημιουργούνται κατά την όπτηση. Με συνδυαστική μελέτη Περιθλασιμετρίας Ακτίνων Χ και Σαρωτικού Ηλεκτρονικού Μικροσκοπίου του κεραμικού υποδείχτηκε η παρουσία αναλλοίωτων φάσεων, προερχόμενων από τις πρώτες ύλες, καθώς και νεοσχηματισμένων κρυστάλλων αλβίτη και μαγνησιοφερρίτη. Τα αποτελέσματα της παρούσας μελέτης δείχνουν ότι η χρήση παραπροϊόντων μπορεί να είναι σημαντική και περιβαλλοντικά φιλική στην παραγωγή φτηνών δομικών κεραμικών.A new ceramic product is introduced by mixing caustic magnesia, produced in the laboratory from pure, high quality magnesite, and natural silt. Bottom ash and red mud, two well known environmentally hazardous industrial by-products, were also added in the mixture. After testing various recipes we concluded that addition of 5% caustic magnesia in the ceramic product greatly enhances its performance. Increase bonding of the ceramic microstructure is attributed to the formation of periclase necks, the concurrent formation of small quantities of amorphous material and the homogeneously distributed pores during the experimental firing of the mixture. Combined X-ray Diffractometry and Scanning Electron Microscopy of the ceramic product revealed the occurrence of unreactive phases, inherited by the raw materials, as well as newly-formed albite and magnesioferrite. Our results show that utilization of by-products may be important and environmental friendly materials in producing low cost ceramic building materials

Direct test of time-reversal symmetry in the entangled neutral kaon system at a ϕ\phi-factory

We present a novel method to perform a direct T (time reversal) symmetry test in the neutral kaon system, independent of any CP and/or CPT symmetry tests. This is based on the comparison of suitable transition probabilities, where the required interchange of in out states for a given process is obtained exploiting the Einstein-Podolsky-Rosen correlations of neutral kaon pairs produced at a $\phi$-factory. In the time distribution between the two decays, we compare a reference transition like the one defined by the time ordered decays $(\ell^-,\pi\pi)$ with the T -conjugated one defined by $(3\pi^0, \ell^+)$. With the use of this and other T conjugated comparisons, the KLOE-2 experiment at DA$\Phi$NE could make a significant test

T and CPT Symmetries in Entangled Neutral Meson Systems

Genuine tests of an asymmetry under T and/or CPT transformations imply the interchange between in-states and out-states. I explain a methodology to perform model-indepedent separate measurements of the three CP, T and CPT symmetry violations for transitions involving the decay of the neutral meson systems in B- and {\Phi}-factories. It makes use of the quantum-mechanical entanglement only, for which the individual state of each neutral meson is not defined before the decay of its orthogonal partner. The final proof of the independence of the three asymmetries is that no other theoretical ingredient is involved and that the event sample corresponding to each case is different from the other two. The experimental analysis for the measurements of these three asymmetries as function of the time interval {\Delta}t > 0 between the first and second decays is discussed, as well as the significance of the expected results. In particular, one may advance a first observation of true, direct, evidence of Time-Reserval-Violation in B-factories by many standard deviations from zero, without any reference to, and independent of, CP-Violation. In some quantum gravity framework the CPT-transformation is ill-defined, so there is a resulting loss of particle-antiparticle identity. This mechanism induces a breaking of the EPR correlation in the entanglement imposed by Bose statistics to the neutral meson system, the so-called {\omega}-effect. I present results and prospects for the {\omega}-parameter in the correlated neutral meson-antimeson states.Comment: Proc. DISCRETE 2010, Symposium on Prospects in the Physics of Discrete Symmetries, December 2010, Rom

On Conceptually Simple Algorithms for Variants of Online Bipartite Matching

We present a series of results regarding conceptually simple algorithms for bipartite matching in various online and related models. We first consider a deterministic adversarial model. The best approximation ratio possible for a one-pass deterministic online algorithm is $1/2$, which is achieved by any greedy algorithm. D\"urr et al. recently presented a $2$-pass algorithm called Category-Advice that achieves approximation ratio $3/5$. We extend their algorithm to multiple passes. We prove the exact approximation ratio for the $k$-pass Category-Advice algorithm for all $k \ge 1$, and show that the approximation ratio converges to the inverse of the golden ratio $2/(1+\sqrt{5}) \approx 0.618$ as $k$ goes to infinity. The convergence is extremely fast --- the $5$-pass Category-Advice algorithm is already within $0.01\%$ of the inverse of the golden ratio. We then consider a natural greedy algorithm in the online stochastic IID model---MinDegree. This algorithm is an online version of a well-known and extensively studied offline algorithm MinGreedy. We show that MinDegree cannot achieve an approximation ratio better than $1-1/e$, which is guaranteed by any consistent greedy algorithm in the known IID model. Finally, following the work in Besser and Poloczek, we depart from an adversarial or stochastic ordering and investigate a natural randomized algorithm (MinRanking) in the priority model. Although the priority model allows the algorithm to choose the input ordering in a general but well defined way, this natural algorithm cannot obtain the approximation of the Ranking algorithm in the ROM model

IEEE 802.11ax Spatial Reuse Improvement: An Interference-Based Channel Access Algorithm

Wi-Fi is the dominant way of connecting indoor mobile devices to the Internet. The main reason behind the huge adoption of this technology is the simplicity of IEEE 802.11 protocols which in turn offer low-cost ownership and maintenance combined with the ability to offer high data rates to end users. The increasing demand in traffic volumes leads to the continuous deployment of access points (APs) resulting in densification of the IEEE 802.11 networks. This fact, instead of enhancing the efficiency of wireless local area networks (WLANs) degrades their overall performance due to cochannel interference between overlapped basic services sets (OBSSs). One of the main goals of the under-development IEEE 802.11ax amendment is to address the WLAN densification problem by improving spatial reuse (SR). In this article we present and evaluate a channel access algorithm, which considers the expected interference that nodes will suffer by a concurrent transmission so to decide if transmission or defer will take place. It is shown that the proposed interference based dynamic channel algorithm (IB-DCA) offers significant SR performance gains comparing to the existing channel access algorithms, in terms of the station mean data rate, for all the stations in a IEEE 802.11ax dense deployment