7,954 research outputs found
Experimental scheme for unambiguous discrimination of linearly independent symmetric states
We propose an optimal discrimination scheme for a case of four linearly
independent nonorthogonal symmetric quantum states, based on linear optics
only. The probability of discrimination is in agreement with the optimal
probability for unambiguous discrimination among N symmetric states [Phys.
Lett. A \textbf{250}, 223 (1998)]. The experimental setup can be extended for
the case of discrimination among nonorthogonal symmetric quantum states
Spacetime-Filling Branes and Strings with Sixteen Supercharges
We discuss branes whose worldvolume dimension equals the target spacetime
dimension, i.e. ``spacetime-filling branes''. In addition to the D9-branes,
there are 9-branes in the NS-NS sectors of both the IIA and IIB strings. The
worldvolume actions of these branes are constructed, via duality, from the
known actions of branes with codimension larger than zero. Each of these types
of branes is used in the construction of a string theory with sixteen
supercharges by modding out a type II string by an appropriate discrete
symmetry and adding 32 9-branes. These constructions are related by a web of
dualities and each arises as a different limit of the Horava-Witten
construction.Comment: 43 pages, LaTeX, 8 figures, uses html.sty, version to appear in Nucl.
Phys.
LANDSAT-4/5 image data quality analysis
A LANDSAT Thematic Mapper (TM) quality evaluation study was conducted to identify geometric and radiometric sensor errors in the post-launch environment. The study began with the launch of LANDSAT-4. Several error conditions were found, including band-to-band misregistration and detector-to detector radiometric calibration errors. Similar analysis was made for the LANDSAT-5 Thematic Mapper and compared with results for LANDSAT-4. Remaining band-to-band misregistration was found to be within tolerances and detector-to-detector calibration errors were not severe. More coherent noise signals were observed in TM-5 than in TM-4, although the amplitude was generally less. The scan direction differences observed in TM-4 were still evident in TM-5. The largest effect was in Band 4 where nearly a one digital count difference was observed. Resolution estimation was carried out using roads in TM-5 for the primary focal plane bands rather than field edges as in TM-4. Estimates using roads gave better resolution. Thermal IR band calibration studies were conducted and new nonlinear calibration procedures were defined for TM-5. The overall conclusion is that there are no first order errors in TM-5 and any remaining problems are second or third order
Breaking arches with vibrations: the role of defects
We present experimental results about the stability of arches against
external vibrations. Two dimensional strings of mutually stabilizing grains are
geometrically analyzed and subsequently submitted to a periodic forcing at
fixed frequency and increasing amplitude. The main factor that determines the
granular arch resistance against vibrations is the maximum angle among those
formed between any particle of the arch and its two neighbors: the higher the
maximum angle is, the easier to break the arch. Based in an analysis of the
forces, a simple explanation is given for this dependence. From this,
interesting information can be extracted about the expected magnitudes of
normal forces and friction coefficients of the particles conforming the arches
The semantic effects of verb raising and its consequences in second language grammars
This article considers whether highly proficient second language speakers of English can distinguish meaning contrasts associated with constructions where there is a raising be, and constructions where there is a non-raising thematic verb, as illustrated in the difference between (1a) and (1b): 1a. Kim is reading a novel (`event-in-progress/existential ? interpretation
On the relationship between pump chirp and single-photon chirp in spontaneous parametric downconversion
We study the chronocyclic character, i.e. the joint temporal and spectral
properties, of the single-photon constituents of photon pairs generated by
spontaneous parametric down conversion. In particular we study how single
photon properties, including purity and single-photon chirp, depend on photon
pair properties, including the type of signal-idler spectral and correlations
and the level of pump chirp.Comment: 13 pages, 6 figure
Evaluation of the ATB 32C, automicrobic system and API 20C using clinical yeast isolates
The ATB 32C (bioMerieux, Spain), AMS-YBC (Vitek System, bioMerieux, Spain) and API 20C (bioMerieux, Spain) systems were evaluated for their reliability in identifying 100 clinical yeast isolates. The ATB 32C, AMS-YBC and API 20C systems correctly identified 97%, 98% and 100% of the isolates respectively. There were no significant differences in incubation periods between ATB 32C and AMS-YBC systems. One isolate of Candida tropicalis was wrongly identified by the ATB 32C and the AMS-YBC systems. The Saccharomyces cerevisiae isolate was wrongly identified by the ATB 32C system while the AMS-YBC failed to identify it and a third isolate of Candida krusei was wrongly identified by the ATB 32C system. The overall accuracy and rapidity of the ATB 32C and AMS-YBC systems were sufficient to permit recommendation of either of these systems for routine use in the clinical microbiology laboratory, although the first system enjoys the advantages of having a wider data-base and the possibility of manual reading
High Specific-Impulse Electrospray Explorer for Deep-Space (HiSPEED): Stage-Based Electrospray Propulsion System for CubeSats
The objective of the High Specific-impulse Electrospray Explorer for Deep-space (HiSPEED) project is to develop an efficient propulsion system to enable deep-space exploration with small satellites. The ion electrospray propulsion system developed at Massachusetts Institute of Technology's (MIT) Space Propulsion Laboratory is one of the first systems to offer compact and efficient propulsion that is compatible with the CubeSat form factor. However, existing thruster heads have lifetimes less than the required firing time for a deep-space mission. Therefore, a stage-based approach is considered where burnt out thruster heads are ejected and replaced, thereby extending the overall lifetime of the propulsion system
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