Human metapneumovirus (HMPV) was recently identified in The Netherlands and was linked to acute respiratory tract illness. In this study, 11 isolates from 10 patients with respiratory disease from ...Quebec, Canada, were tested by a reverse-transcriptase polymerase chain reaction based on the fusion protein gene. Identified sequences were consistent with HMPV. The patients were 2 months to 87 years of age (median age, 58 years) and presented with acute respiratory tract illness during the winter season. Sequence studies of the nucleocapsid, fusion, and polymerase genes identified 2 main lineages of HMPV and cocirculation of both lineages during the same year. These findings support a previous finding that HMPV is a human respiratory pathogen that merits further study.
We estimated the proportion of persons with pandemic (H1N1) 2009 who were shedding infectious virus at diagnosis and on day 8 of illness. In households with confirmed cases, nasopharyngeal swabs were ...collected on all members and tested by PCR and virus culture. Of 47 cases confirmed by PCR at <7 days of illness, virus culture was positive in 92% (11/12) of febrile and 63% (22/35) of afebrile persons. Of 43 persons with PCR-confirmed pandemic (H1N1) 2009 from whom a second specimen was collected on day 8, 74% remained PCR positive and 19% were culture positive. If the 73 symptomatic household members without PCR-confirmed illness are assumed to have pandemic (H1N1) 2009, a minimum of 8% (6/73) of case-patients shed replicating virus on day 8. Self-isolation only until fever abates appears insufficient to limit transmission. Self-isolation for a week may be more effective, although some case-patients still would shed infectious virus.
The human metapneumovirus (hMPV) was recently identified and linked to acute respiratory tract infections (ARTI). To assess the clinical importance of this virus in infants and children, we developed ...a rapid and efficient reverse transcription-PCR-based screening method for a large volume of samples and tested retrospectively a collection of 1,132 respiratory specimens submitted over a full year period to the virology laboratory of a large tertiary care pediatric center in Montreal, Canada. A total of 41 samples from 37 patients were positive by this method. During the winter months of 2001, up to 8% of specimens submitted for respiratory virus testing were hMPV positive. Sequencing data of the hMPV M gene revealed that two genogroups of the virus, each of which can be divided into two subgroups, cocirculated during this time period. A case-controlled study was conducted to compare the symptoms associated with hMPV infection with those involving other etiologic agents causing ARTI. Symptoms most frequently observed in hMPV-positive patients were cough, wheezing, and dyspnea, although the symptomatology could differ substantially from patient to patient. No distinct symptom profile could be associated with hMPV. Three nosocomial cases of hMPV infection were identified. Together, our data suggest that hMPV is a significant cause of symptomatic respiratory tract infections in infants and children. The incidence of the disease and the morbidity associated with the infection justify adding hMPV to the list of common respiratory viruses routinely screened for by clinical laboratories.
A fundamental hypothesis of quantitative finance is that stock price variations are independent and can be modeled using Brownian motion. In recent years, it was proposed to use rescaled range ...analysis and its characteristic value, the Hurst exponent, to test for independence in financial time series. Theoretically, independent time series should be characterized by a Hurst exponent of 1/2. However, finite Brownian motion data sets will always give a value of the Hurst exponent larger than 1/2 and without an appropriate statistical test such a value can mistakenly be interpreted as evidence of long term memory. We obtain a more precise statistical significance test for the Hurst exponent and apply it to real financial data sets. Our empirical analysis shows no long-term memory in some financial returns, suggesting that Brownian motion cannot be rejected as a model for price dynamics.
When conducting remote mine-hunting operations with a sidescan-sonar-equipped vehicle, a lawn-mowing search pattern is standard if no prior information on potential target locations is available. ...Upon completion of this initial search, a list of contacts is obtained. The overall classification performance can be significantly improved by revisiting these contacts to collect additional looks. This paper provides, for the first time, a link between the recent literature which finds optimal secondary looks and optimal route planning software. Automated planning algorithms are needed to generate multiaspect routes to improve the performance of mine-hunting systems and increase the capability of navies to efficiently clear potential mine fields. This paper introduces two new numerical techniques designed to enable current remote mine-hunting systems to achieve secondary paths minimizing the total distance to be traveled and satisfying all motion and imaging constraints. The first "local" approach is based on a sequential algorithm dealing with more tractable subproblems, while the second is "global" and based on simulated annealing. These numerical techniques are applied to two test sites created for the Mongoose sea trial held at the 2007 Autonomous Underwater Vehicle (AUV) Fest, Panama City, FL. Highly satisfactory planning solutions are obtained.
Serum antibody levels can be used to measure the humoral immune response against human papillomaviruses (HPV). We developed and validated a rapid, technically simple and relatively inexpensive ...multiplex non-competitive Luminex-based immunoassay (ncLIA) to measure total IgG antibody levels against four HPV types. For the assay’s solid phase, virus-like particles (VLPs) of HPV6, 11, 16 and 18 were bound to heparin-coated beads. HPV serum antibody levels binding to the VLPs were quantified using a phycoerithrin-conjugated secondary polyclonal donkey anti-human IgG antibody. Standardization and validation of the ncLIA were performed using 96 paired serum and genital samples from participants in the HITCH cohort study, including young women (aged 18–24 years) and their male sexual partners (aged 18+) in Montreal, Canada. Results from the ncLIA were compared to a validated Luminex immunoassay from PPD laboratories using Pearson’s correlation coefficients, receiver operating characteristic curves and logistic regression. Our assay had good inter- and intra-assay variability. The correlation of serum antibody levels between the ncLIA and validation assay was highest for HPV16 and HPV11 (
r
=0.90), followed by HPV6 (
r
=0.86) and HPV18 (
r
=0.67). The ncLIA was better able to predict HPV DNA positivity in genital samples than the validation assay for HPV16 area under the curve (AUC) 0.65 versus 0.52,
P
=0.001 and HPV18 AUC 0.71 versus 0.57,
P
=0.024. AUCs for HPV6 and HPV11 were similar between the two assays (0.70 versus 0.71,
P
=0.59, and 0.88 versus 0.96,
P
=0.08, respectively). The developed ncLIA is useful for measuring total IgG antibody response following natural infection or vaccination against four HPV VLPs included in the quadrivalent vaccine.
Specimens (n = 287) from 59 gastroenteritis outbreaks collected from February 1997 to March 1999 were analyzed by reverse transcriptase—polymerase chain reaction. The majority of outbreaks (88%) were ...associated with Norwalk-like viruses. Molecular analyses of strains from 46 outbreaks showed the cocirculation during the 1998–1999 winter of 2 genogroup II clusters, accounting for 57% and 28% of outbreaks, respectively. An important genetic diversity was observed during this 2-year period. Thirteen different genogroup II strains and 3 different genogroup I strains were found. Genogroup I strains, although from the same cluster, were highly divergent (9%–16%). Epidemiologic and molecular data indicate that several introductions did not result in any major shift of prominent strains, whereas 1 apparently established itself. Some point mutations allowed corroboration of epidemiologic links and strongly suggest that, in several instances, sharing staff and/or transfer of patients between health care institutions can create a significant risk for Norwalk-like virus dissemination.
This work addresses the task of underwater object recognition in sonar imagery when both human operators and automated algorithms are available. We discuss the issues that have impeded previous ...attempts at automation, raise key insights related to human perception, present strategies to exploit the skills of humans and computers synergistically, and demonstrate the utility of the proposed approaches on a real object-recognition task employing actual humans acting as operators. Importantly, the strategies outlined here can be immediately adopted in existing (unautomated) target recognition systems with minimal cost, effort, and risk, while still achieving potentially significant performance gains. Moreover, this progress lays the foundation for the acceptance of still-further automated systems in the future. Experimental results are provided from a real mine-search exercise at sea, with recognition performance as a function of human operator effort given for various human-computer divisions of labor.
An algorithm for the in situ adaptation of the survey route of an autonomous underwater vehicle (AUV) equipped with side-looking sonars was recently proposed. This algorithm immediately exploits the ...through-the-sensor data that is collected during a mission in order to ensure that quality data is collected everywhere in the area of interest. By introducing flexibility into the survey of the AUV, various limitations of pre-planned surveys are overcome. In particular, the need to re-deploy the AUV (to fill gaps in the data coverage) is obviated. In turn, the time and costs of the data-collection mission are significantly reduced. In this work, we improve the aforementioned algorithm by introducing an additional constraint to the survey track-selection process. This modification significantly increases the efficiency of a survey by further reducing both transit time and the overall number of tracks executed. In particular, the revised algorithm more closely approximates the optimal survey route that would be executed if perfect knowledge of the future sonar performance during the mission were known a priori.
In this paper, the classification of an object on the seabed from two sidescan sonar looks is considered. Four different approaches to fusing the information from the individual looks are described. ...The first method uses a kernel regression classification method with the combined feature (CF) vectors from the two looks. The other three approaches are based upon the Dempster-Shafer (DS) fusion of the outputs from a single-look kernel-based classifier. They differ with respect to the manner in which the DS masses for each look are derived from the single-look classifier. The four approaches are evaluated with Klein 5500 sidescan sonar data collected from four classes: rock and three dummy mine types: manta, rockan, and cylinder. The sonar data were collected in October 2005 when the Defence Research and Development Canada Atlantic (DRDC-Atlantic, Dartmouth, NS, Canada), participated with the NATO Undersea Research Centre (NURC, La Spezia, Italy) and Groupe D'Études Sous-Marines de l'Atlantique (GESMA, Brest, France) in a joint trial (CITADEL) with the DRDC remote, semisubmersible vehicle DORADO. Using these data, it is shown that two of the approaches for DS mass assignments yield two-look classification performances very similar to each other and to the CF method. The DS approaches have the advantage that they do not require explicit training with a CF set.
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