683 research outputs found
Follow-up question handling in the IMIX and Ritel systems: A comparative study
One of the basic topics of question answering (QA) dialogue systems is how follow-up questions should be interpreted by a QA system. In this paper, we shall discuss our experience with the IMIX and Ritel systems, for both of which a follow-up question handling scheme has been developed, and corpora have been collected. These two systems are each other's opposites in many respects: IMIX is multimodal, non-factoid, black-box QA, while Ritel is speech, factoid, keyword-based QA. Nevertheless, we will show that they are quite comparable, and that it is fruitful to examine the similarities and differences. We shall look at how the systems are composed, and how real, non-expert, users interact with the systems. We shall also provide comparisons with systems from the literature where possible, and indicate where open issues lie and in what areas existing systems may be improved. We conclude that most systems have a common architecture with a set of common subtasks, in particular detecting follow-up questions and finding referents for them. We characterise these tasks using the typical techniques used for performing them, and data from our corpora. We also identify a special type of follow-up question, the discourse question, which is asked when the user is trying to understand an answer, and propose some basic methods for handling it
Radiotherapy of choroidal metastases.
Abstract
Purpose: This retrospective study was undertaken to clarify the role of high energy external beam radiation therapy (EBRT) and to
determine its safety and efficacy on local control and visual acuity in patients suffering from choroidal metastases (CM).
Materials and methods: The records of 58 consecutive patients treated with EBRT between 1970 and 1993 were analyzed. The female to
male ratio was 2.9 and the median age was 59 years (range 40–81 years). Thirty-six patients (62%) had unilateral CM and 22 patients had
bilateral CM. The mean number of lesions per eye was two. Retinal detachment was present in 65% of cases. The primary tumour (PT) was
breast carcinoma for 38 patients (75%), lung carcinoma for 10 patients (17%) and gastrointestinal, genitourinary or unknown PT for the
remaining 10 patients. The median interval of time between the PT and the CM was 55 months (range 0–228 months). All patients were
treated with megavoltage irradiation. The median prescribed dose was 35.5 Gy (range 20–53 Gy) normalized at a 2 Gy per fraction
schedule with an a/b value of 10 Gy. Various techniques were used and whenever possible the lens was spared. Ten patients with unilateral
disease were treated in both eyes.
Results: The tumour response was slow. When assessed after 3 months or more, the complete response rate was 53% with significantly
better results for doses higher than 35.5 Gy (72 versus 33%; P = 0.009). Visual acuity was improved or stabilized in 62% of patients, with
also significantly better results when doses higher than 35.5 Gy (P = 0.014) were administered. Amongst 26 patients with unilateral CM
who had no elective contralateral irradiation, three developed metastasis in the opposite eye versus none of the 10 patients who had bilateral
irradiation. Five complications occurred (three cataracts, one retinopathy and one glaucoma).
Conclusion: Radiation therapy is an efficient and safe palliative treatment for choroidal metastases and it helps the preservation of vision.
Thus, there is a major impact on the quality of life in a group of patients with an almost uniformly fatal prognosis. Both tumour response
and visual acuity are significantly improved if doses higher than 35.5 Gy are administered. Whenever possible, a lens sparing technique
should be used. Ó 1998 Elsevier Science Ireland Ltd
Classical simulation of entanglement swapping with bounded communication
Entanglement appears under two different forms in quantum theory, namely as a
property of states of joint systems and as a property of measurement
eigenstates in joint measurements. By combining these two aspects of
entanglement, it is possible to generate nonlocality between particles that
never interacted, using the protocol of entanglement swapping. We show that
even in the more constraining bilocal scenario where distant sources of
particles are assumed to be independent, i.e. to share no prior randomness,
this process can be simulated classically with bounded communication, using
only 9 bits in total. Our result thus provides an upper bound on the
nonlocality of the process of entanglement swapping.Comment: 6 pages, 1 figur
HFI L2 DPC destripping and mapmaking modules
PoS(CMB2006)049International audienceThe data processing of the data from the High Frequency Instrument (HFI) of the Planck mission will use several modules. Destriping is expected to play a central role in the mapmaking stage. This paper outlines two existing HFI l2 DPC destriping modules together with estimations of their performances. MOKAPIX is a temperature data destriping tool based on scanning redundancies on the sky. We have developped another modules, BOGOPIX , based on the same philosophy, to perform simultaneously destriping and relative intercalibration
Common peroneal nerve palsy complicating knee dislocation and bicruciate ligaments tears
SummaryIntroductionThe occurrence rate of common peroneal nerve (CPN) palsy associated with knee dislocation or bicruciate ligament injury ranges from 10 to 40%. The present study sought first to describe the anatomic lesions encountered and their associated prognoses and second to recommend adequate treatment strategy based on a prospective multicenter observational series of knee ligament trauma cases.Material and methodsTwelve out of 67 knees treated for dislocation or bicruciate lesion presented associated CPN palsy: two females, 10 males; mean age, 32 years. Four sports injuries, three traffic accidents and five other etiologies led to seven complete dislocations and five bicruciate ruptures. Four cases involved associated popliteal artery laceration ischemia; one of the dislocations was open. Paralysis was total in eight cases and partial in four. There were two complete ruptures, three contusions with CPN in continuity stretch lesions and three macroscopically normal aspects.ResultsAt a minimum 1 year's follow-up, regardless of the initial surgical technique performed, recovery was complete in six cases, partial (in terms of motor function) in one and absent in five. Without specific CPN surgery, spontaneous recovery was partial in one case, complete in two and absent in none. Following simple emergency or secondary neurolysis, remission was total in four cases and absent in one. Three nerve grafts were all associated with non-recovery.DiscussionThe present results agree with literature findings. Palsy rates varied with trauma circumstances and departmental recruitment. Neurologic impairment was commensurate to ligamentary damages. The anatomic status of the CPN, subjected to violent traction by dislocation, was the most significant prognostic factor for neurologic recovery. In about 25% of dislocations, contusion-elongation over several centimeters was associated with as poor a prognosis as total rupture. CPN neurolysis is recommended when early clinical and EMG recovery fails to progress and/or in case of lateral ligamentary reconstruction. Possible peripheral nerve impairment needs to be included in the overall functional assessment of treatment for severe ligaments injuries and knee dislocation.Level of evidenceLevel IV, prospective study
Status of the LHCb magnet system
The LHCb experiment focuses on the precision measurement of CP violation and rare decays in the B-meson system. It plans to operate with an average luminosity of ~cms, which should be obtained from the beginning of the LHC operation. The LHCb detector exploits the forward region of the pp collisions at the LHC collider. It requires a single-arm spectrometer for the separation and momentum measurement of the charged particles with a large dipole magnet of a free aperture of ~mrad horizontally and ~mrad vertically. The magnet is designed for a total integrated field of 4~Tm. The pole gap is 2.2 to 3.5~m vertically (the direction of the field) and 2.6 to 4.2~m horizontally. The overall length of the magnet (in beam direction) is 5~m and its total weight about 1500~t. The power dissipation in the aluminium coils will be 4.2~MW. The magnet yoke is constructed from low carbon steel plates of 100~mm thickness. The maximum weight of one plate does not exceed 25~t. The coils are wound from large hollow aluminium conductor of cross-section with a central cooling channel of 25~mm diameter for the pressurized demineralized water. Each of the two coils is composed of 15~monolayer pancakes of 15~turns per pancake. To reach good field quality the coils are bent by 45 towards the gap along the horizontal aperture of ~mrad and the pole pieces have large shims. The underlying magnet design, its present status and milestones will be reviewed
Planck-LFI radiometers' spectral response
The Low Frequency Instrument (LFI) is an array of pseudo-correlation
radiometers on board the Planck satellite, the ESA mission dedicated to
precision measurements of the Cosmic Microwave Background. The LFI covers three
bands centred at 30, 44 and 70 GHz, with a goal bandwidth of 20% of the central
frequency.
The characterization of the broadband frequency response of each radiometer
is necessary to understand and correct for systematic effects, particularly
those related to foreground residuals and polarization measurements. In this
paper we present the measured band shape of all the LFI channels and discuss
the methods adopted for their estimation. The spectral characterization of each
radiometer was obtained by combining the measured spectral response of
individual units through a dedicated RF model of the LFI receiver scheme.
As a consistency check, we also attempted end-to-end spectral measurements of
the integrated radiometer chain in a cryogenic chamber. However, due to
systematic effects in the measurement setup, only qualitative results were
obtained from these tests. The measured LFI bandpasses exhibit a moderate level
of ripple, compatible with the instrument scientific requirements.Comment: 16 pages, 9 figures, this paper is part of the Prelaunch status LFI
papers published on JINST:
http://www.iop.org/EJ/journal/-page=extra.proc5/jins
Soft tissue reconstruction after pelvic amputation: The efficacy and reliability of free fillet flap reconstruction
Background: The majority of hindquarter amputation defects can be reconstructed with local anterior or posterior thigh flaps. Less than 5% of soft tissue defects require free flap reconstruction after tumour resection. Lower extremity fillet flap is described for reconstructing such defects, but the majority of publications are case reports or short single institutional series. There is a lack of data regarding the oncological outcomes of this highly selected patient group. Methods: Three tertiary sarcoma units treated twelve patients with hindquarter amputation or hip disarticulation for oncological indications with a free flap reconstruction of the soft tissue defect. Results: The median age of patients was 60 (range 12-76) years. Bone resection was carried out through the SI-joint in six patients and through the sacrum in five patients, with one patient undergoing hip disarticulation. Nine patients had R0 resection margin and three had R1 resection. The median surgical time and flap ischaemia time was 420 (249-650) and 89 (64-210) min, respectively. Median hospital and ICU stay was 18 (10-42) and 3 (1-8) days, respectively. Median blood loss was 2400 (950-10000) ml. There were three returns to theatre due to vascular compromise, with one total flap loss due to arterial thrombosis. Overall survival was 58% (95%CI 28-91%) both at 1-year and at 3-years. Discussion: Carefully selected patients requiring hindquarter amputation with extensive soft tissue defect necessitating free flap reconstruction can be reconstructed with a lower extremity free fillet flap with low rate of local wound complications. Survival of these patients is similar to that in patients requiring less extensive resection. Keywords: Fillet flap; Free flap; Hindquarter amputation; Hip disarticulation; Sarcoma; Survival.Background: The majority of hindquarter amputation defects can be reconstructed with local anterior or posterior thigh flaps. Less than 5% of soft tissue defects require free flap reconstruction after tumour resection. Lower extremity fillet flap is described for reconstructing such defects, but the majority of publications are case reports or short single institutional series. There is a lack of data regarding the oncological outcomes of this highly selected patient group. Methods: Three tertiary sarcoma units treated twelve patients with hindquarter amputation or hip disarticulation for oncological indications with a free flap reconstruction of the soft tissue defect. Results: The median age of patients was 60 (range 12-76) years. Bone resection was carried out through the SI-joint in six patients and through the sacrum in five patients, with one patient undergoing hip disarticulation. Nine patients had R0 resection margin and three had R1 resection. The median surgical time and flap ischaemia time was 420 (249-650) and 89 (64-210) min, respectively. Median hospital and ICU stay was 18 (10-42) and 3 (1-8) days, respectively. Medianblood loss was 2400 (950-10000) ml. There were three returns to theatre due to vascular compromise, with one total flap loss due to arterial thrombosis. Overall survival was 58% (95%CI 28-91%) both at 1-year and at 3-years. Discussion: Carefully selected patients requiring hindquarter amputation with extensive soft tissue defect necessitating free flap reconstruction can be reconstructed with a lower extremity free fillet flap with low rate of local wound complications. Survival of these patients is similar to that in patients requiring less extensive resection. (c) 2020 British Association of Plastic, Reconstructive and Aesthetic Surgeons. Published by Elsevier Ltd. All rights reserved.Peer reviewe
Maximum likelihood estimation of locus-specific mutation rates in Y-chromosome short tandem repeats
Motivation: Y-chromosome short tandem repeats (Y-STRs) are widely used for population studies, forensic purposes and, potentially, the study of disease, therefore knowledge of their mutation rate is valuable. Here we show a novel method for estimation of site-specific Y-STR mutation rates from partial phylogenetic information, via the maximum likelihood framework
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