Towards an automated query modification assistant

Users who need several queries before finding what they need can benefit from an automatic search assistant that provides feedback on their query modification strategies. We present a method to learn from a search log which types of query modifications have and have not been effective in the past. The method analyses query modifications along two dimensions: a traditional term-based dimension and a semantic dimension, for which queries are enriches with linked data entities. Applying the method to the search logs of two search engines, we identify six opportunities for a query modification assistant to improve search: modification strategies that are commonly used, but that often do not lead to satisfactory results.Comment: 1st International Workshop on Usage Analysis and the Web of Data (USEWOD2011) in the 20th International World Wide Web Conference (WWW2011), Hyderabad, India, March 28th, 201

Group IV phosphinimide complexes in catalysis.

Significant progress has been made in various aspects of the chemistry of Group IV phosphinimide complexes, particularly in their use as highly active catalysts for olefin polymerization upon activation by an appropriate Lewis acid. Advances in synthetic methods have provided routes for the preparation of phosphinimide amide inorganic and organometallic products via metathesis or protonation methods. Testing of TiCp(NPtBu 3)X2 (X = Cl, Me, NMe2) as hydroamination catalysts has shown that these complexes are inactive for this purpose under the conditions employed. In addition, numerous synthetic endeavours have revealed that the titanium phosphinimide complexes are reluctant to form isolable imide derivatives. However, through efforts to prepare ligand transfer reagents, magnesium phosphinimide complexes have been developed that initiate the polymerization of methyl methacrylate at ambient temperatures, probably via a radical process. Examination of the highly active phosphinimide polymerization catalysts inferred that the presence of a cyclopentadienide ligand, in addition to bulky alkyl groups on the phosphorus atom, was beneficial to prolong catalytic activity. In an effort to use catalysts that encompass this apparent advantage while preparing polymers of different composition that remain of industrial value, a series of bimetallic titanium complexes of the general formula p-(CH2PR2NTiCp\u27X 2)2C6H4 (Cp\u27 = Cp, Cp*; R = tBu, Cy; X = Cl, Me) were prepared. For comparison, their monometallic analogues, TiCp(NPR2Bn)X2, were also synthesized and tested using the same polymerization protocol. Several important features about these catalysts were ascertained upon examination of the polymer properties. Typically, high catalytic activities were observed, and low polydispersity polymers were generated when the discrete activator [Ph3C][B(C 6F5)4] was used. However, use of MAO as the activator in the presence of precatalysts that have a phosphinimide ligand with a benzyl substituent resulted in polymers with a broad molecular weight distribution. Another observation that transpired from this series of polymerization experiments was that the activity increased as the steric bulk of the ligands increased. Finally, a systematic investigation into the synthesis and utility of zirconium phosphinimide complexes as olefin polymerization catalysts was performed. (Abstract shortened by UMI.) Source: Dissertation Abstracts International, Volume: 66-07, Section: B, page: 3705. Thesis (Ph.D.)--University of Windsor (Canada), 2003

Molecular Genetic Insights in Cytogenetically-Normal Pediatric Acute Myeloid Leukemia

Hematopoiesis is the process of formation of new blood cells.1 During embryonic development, the process starts in the yolk sac, in so called blood islands. As development of the embryo progresses, blood cell formation continues predominantly in the liver, and after birth the bone marrow takes over the process of hematopoiesis. New blood cells continuously need to be generated throughout life, as the majority of mature blood cells have a limited life-span. In a healthy adult, this results in the estimated production of approximately 1010 new blood cells per hour.1 All different types of mature blood cells originate from a pool of self-renewing hematopoietic stem cells (HSC’s) that resides in the bone marrow. In a strictly regulated process, the multipotent HSC’s can differentiate into either a common myeloid or common lymphoid progenitor cells (Figure 1). While the lymphoid progenitor cells will differentiate and mature into either B-lymphocytes, T-lymphocytes, or natural killer cells, the myeloid progenitor cells will give rise to the other white blood cells (leukocytes) such as granulocytes (i.e. neutrophils, basophils and eosinophils), monocytes/macrophages and mast cells, but also to the red blood cells (erythrocytes) and the platelets (thrombocytes)

Query Expansion of Zero-Hit Subject Searches: Using a Thesaurus in Conjunction with NLP Techniques

The focus of our study is zero-hit queries in keyword subject searches and the effort of increasing recall in these cases by reformulating and, then, expanding the initial queries using an external source of knowledge, namely a thesaurus. To this end, the objectives of this study are twofold. First, we perform the mapping of query terms to the thesaurus terms. Second, we use the matched terms to expand the user’s initial query by taking advantage of the thesaurus relations and implementing natural language processing (NLP) techniques. We report on the overall procedure and elaborate on key points and considerations of each step of the process

Nano-mechanical tuning and imaging of a photonic crystal micro-cavity resonance

We show that nano-mechanical interaction using atomic force microscopy (AFM) can be used to map out mode-patterns of an optical micro-resonator with high spatial accuracy. Furthermore we demonstrate how the Q-factor and center wavelength of such resonances can be sensitively modified by both horizontal and vertical displacement of an AFM tip consisting of either Si3N4 or Si material. With a silicon tip we are able to tune the resonance wavelength by 2.3 nm, and to set Q between values of 615 and zero, by expedient positioning of the AFM tip. We find full on/off switching for less than 100 nm vertical, and for 500 nm lateral\ud displacement at the strongest resonance antinode locations

Interactions with a photonic crystal micro-cavity using AFM in contact or tapping mode operation

In this paper we show how the evanescent field of a localized mode in a photonic crystal micro-cavity can be perturbed by a nano-sized AFM tip. Due to the high field intensities in the cavity, we can see a significant change in output power when the tip is brought into the evanescent field in either contact or tapping mode operation. We find a 4 dB modulation, when using a $Si_{3}N_{4}$ tip and we show that the transmittance can be tuned from 0.32 to 0.8 by varying the average tapping height