BEAR: Benchmarking the Efficiency of RDF Archiving

There is an emerging demand on techniques addressing the problem of efficiently archiving and (temporal) querying different versions of evolving semantic Web data. While systems archiving and/or temporal querying are still in their early days, we consider this a good time to discuss benchmarks for evaluating storage space efficiency for archives, retrieval functionality they serve, and the performance of various retrieval operations. To this end, we provide a blueprint on benchmarking archives of semantic data by defining a concise set of operators that cover the major aspects of querying of and interacting with such archives. Next, we introduce BEAR, which instantiates this blueprint to serve a concrete set of queries on the basis of real-world evolving data. Finally, we perform an empirical evaluation of current archiving techniques that is meant to serve as a first baseline of future developments on querying archives of evolving RDF data. (authors' abstract)Series: Working Papers on Information Systems, Information Business and Operation

Iterative Learning of Relation Patterns for Market Analysis with UIMA

Blohm S, Umbrich J, Cimiano P, Sure Y. Iterative Learning of Relation Patterns for Market Analysis with UIMA. In: UIMA Workshop at GLDV Frühjahrstagung. 2007

Evaluating Query and Storage Strategies for RDF Archives

There is an emerging demand on efficiently archiving and (temporal) querying different versions of evolving semantic Web data. As novel archiving systems are starting to address this challenge, foundations/standards for benchmarking RDF archives are needed to evaluate its storage space efficiency and the performance of different retrieval operations. To this end, we provide theoretical foundations on the design of data and queries to evaluate emerging RDF archiving systems. Then, we instantiate these foundations along a concrete set of queries on the basis of a real-world evolving dataset. Finally, we perform an empirical evaluation of various current archiving techniques and querying strategies on this data that is meant to serve as a baseline of future developments on querying archives of evolving RDF data

Coherent acceleration of rubidium atoms using multiphoton adiabatic transfer

Rezonáns lézersugárzás segítségével nemcsak az atom belső állapota manipulálható. Egy gerjesztés, illetve spontán vagy indukált emisszió az elnyelt vagy kibocsátott fotonlendület miatt az egész atom mozgását is befolyásolja. Ilyen módon az atomok célzottan lassíthatóak vagy gyorsíthatóak, illetve lehet őket hűteni és csapdázni. Atomok koherens manipulálása csak indukált folyamatokon keresztül lehetséges (gerjesztés és indukált emisszió) - a spontán emisszió lerombolja a kvantumállapot koherenciáját. Lézerimpulzussal létrehozott indukált folyamatok sokféleképpen használhatóak atomok mozgásának manipulációjára (pl: atomnyalábok eltérítése vagy fókuszálása) és számos esetben lehetőséget nyújtanak az atomi hullámcsomagok koherenciájának megőrzésére. A koherencia megőrzéséhez fontos, hogy a kölcsönhatásban a teljes populáció átvihető legyen, erre egy hatékony és robusztus megoldás az adiabatikus átmenet [1] [2] [3] [4] [5] [6] [7]. Ezek a módszerek gyakran két egymással szemben haladó lézerimpulzust használnak, melyek egymás után kölcsönhatva az atommal (az atom spontán élettartamánál rövidebb időn belül) kényszerítik az atomot populációváltásra (alapállapotból gerjesztett állapotba és vissza). Egy foton elnyelésével az alapállapotból a gerjesztett állapotba jutó atom a foton lendületét is elnyeli, és ℏ impulzust kap. Amennyiben a gerjesztést követően egy másik ellentétes irányú, a gerjesztő impulzushoz hasonló lézerimpulzussal hat kölcsön az atom, akkor indukált emisszió jön létre. Ezáltal a rendszer ismét ugyanabban az irányban még egy ℏ impulzust kap. Fontos, hogy addig történjen meg a második nyaláb kölcsönhatása az atomokkal, míg azok gerjesztése számottevően nem csökken a spontán emisszió miatt. Tehát a rendszer így összesen 2ℏ impulzushoz jut. [8] [9] [10] Fontos eredményt mutat, amikor a kölcsönhatást végző szembehaladó lézerimpulzusok nem külön-külön, hanem egymással részben átfedve egyszerre hatnak kölcsön az atommal. A szimulációs modellek azt mutatták, hogy az atom a várt 2ℏ helyett ennek egész számú többszörösét is képes megkapni. [11] [12] [13]. Ez akkor lehetséges, ha a folyamat adiabatikus, amely a kölcsönhatás paramétereire (lézerintenzitás, impulzushossz, frekvenciafutás, impulzusok átfedése, stb.) nézve szigorú specifikációt jelent. A jelenség neve többfotonos adiabatikus átmenet. Az atomok gyorsításának ilyen kompakt módon fontos gyakorlati haszna lehet

PLoS One

ObjectivesTo identify the reasons patients miss taking their antiretroviral therapy (ART) and the proportion who miss their ART because of symptoms; and to explore the association between symptoms and incomplete adherence.MethodsSecondary analysis of data collected during a cross-sectional study that examined ART adherence among adults from 18 purposefully selected sites in Tanzania, Uganda, and Zambia. We interviewed 250 systematically selected patients per facility ( 6518 years) on reasons for missing ART and symptoms they had experienced (using the HIV Symptom Index). We abstracted clinical data from the patients\u2019 medical, pharmacy, and laboratory records. Incomplete adherence was defined as having missed ART for at least 48 consecutive hours during the past 3 months.ResultsTwenty-nine percent of participants reported at least one reason for having ever missed ART (1278/4425). The most frequent reason was simply forgetting (681/1278 or 53%), followed by ART-related hunger or not having enough food (30%), and symptoms (12%). The median number of symptoms reported by participants was 4 (IQR: 2\u20137). Every additional symptom increased the odds of incomplete adherence by 12% (OR: 1.1, 95% CI: 1.1\u20131.2). Female participants and participants initiated on a regimen containing stavudine were more likely to report greater numbers of symptoms.ConclusionsSymptoms were a common reason for missing ART, together with simply forgetting and food insecurity. A combination of ART regimens with fewer side effects, use of mobile phone text message reminders, and integration of food supplementation and livelihood programmes into HIV programmes, have the potential to decrease missed ART and hence to improve adherence and the outcomes of ART programmes.2016PEPFAR/United States26788919PMC4720476703

Pre-Excitation Studies for Rubidium-Plasma Generation

The key element in the Proton-Driven-Plasma-Wake-Field-Accelerator (AWAKE) project is the generation of highly uniform plasma from Rubidium vapor. The standard way to achieve full ionization is to use high power laser which can assure the over-barrier-ionization (OBI) along the 10 meters long active region. The Wigner-team in Budapest is investigating an alternative way of uniform plasma generation. The proposed Resonance Enhanced Multi Photon Ionization (REMPI) scheme probably can be realized by much less laser power. In the following the resonant pre-excitations of the Rb atoms are investigated, theoretically and the status report about the preparatory work on the experiment are presented.Comment: 8 pages, 6 figures, submitted to Nucl. Inst. and Meth. in Phys. Res.

Stabilization and time resolved measurement of the frequency evolution of a modulated diode laser for chirped pulse generation

We have developed experimental methods for the generation of chirped laser pulses of controlled frequency evolution in the nanosecond pulse length range for coherent atomic interaction studies. The pulses are sliced from the radiation of a cw external cavity diode laser while its drive current, and consequently its frequency, are sinusoidally modulated. By the proper choice of the modulation parameters, as well as of the timing of pulse slicing, we can produce a wide variety of frequency sweep ranges during the pulse. In order to obtain the required frequency chirp, we need to stabilize the center frequency of the modulated laser and to measure the resulting frequency evolution with appropriate temporal resolution. These tasks have been solved by creating a beat signal with a reference laser locked to an atomic transition frequency. The beat signal is then analyzed, as well as its spectral sideband peaks are fed back to the electronics of the frequency stabilization of the modulated laser. This method is simple and it has the possibility for high speed frequency sweep with narrow bandwidth that is appropriate, for example, for selective manipulation of atomic states in a magneto-optical trap