249 research outputs found
Shubnikov-de Haas oscillations in SrTiO3\LaAlO3 interface
Quantum magnetic oscillations in SrTiO3/\LaAlO3 interface are observed. The
evolution of their frequency and amplitude at various gate voltages and
temperatures is studied. The data are consistent with the Shubnikov de-Haas
theory. The Hall resistivity rho exhibits nonlinearity at low magnetic field.
It is fitted assuming multiple carrier contributions. The comparison between
the mobile carrier density inferred from the Hall data and the oscillation
frequency suggests multiple valley and spin degeneracy. The small amplitude of
the oscillations is discussed in the framework of the multiple band scenario
Increasing incidence of non-typhi Salmonella bacteremia among children living in southern Israel
AbstractObjectives: To determine if the epidemiology of Salmonella gastroenteritis and childhood bacteremia among the two ethnic populations (Jews and Bedouins) living in southern Israel has changed in recent years.Methods: Retrospective review of laboratory records and medical charts of patients from whom non-typhi salmonellae were isolated from stool and blood cultures in the 1990–1995 period.Results: The overall incidence of enteric Salmonella infections was 123.5 per 100 000 inhabitants and remained stable during the study period. The incidence of bacteremia among children younger than 4 years increased from 9.3 per 100 000 in the 1990–1992 period to 26.8 per 100 000 in the 1993–1995 period (P<0.01). This increment was especially caused by Salmonella virchow and S. enteritidis, which were also isolated with increasing frequency from stool cultures. The Bedouin population was underrepresented among stool isolates, whereas its representation among blood isolates closely resembled the fraction of this ethnic group in the overall population of the area.Conclusions: The incidence of enteric salmonellosis has remained stable at a high endemic level in recent years in southern Israel. The incidence of children's bacteremia has experienced a significant increase, associated with S. virchow and S. enteritidis. Differences in the utilization of medical services may explain differences in the epidemiology of Salmonella infections found in the two resident ethnic groups
Nasopharyngeal Carriage of Streptococcus pneumoniae Shortly before Vaccination with a Pneumococcal Conjugate Vaccine Causes Serotype-Specific Hyporesponsiveness in Early Infancy
Background. The antibody response to pneumococcal conjugate vaccines (PCVs) in infants is variable. Factors responsible for this variability have not been fully elucidated. The objective of this study was to investigate whether pneumococcal carriage around the time of the first dose of 7-valent PCV (PCV7) affects serotype-specific immunologic response. Methods. Healthy 2-month old infants were randomized to receive 2 (at the ages of 4 and 6 months) or 3 (at the ages of 2, 4, and 6 months) PCV7 doses and a booster dose (at the age of 12 months). Nasopharyngeal or oropharyngeal specimens were obtained for culture shortly before the first PCV7 dose. Serotype-specific immunoglobulin (Ig) G levels were measured at ages 2, 7, and 13 months. Results. Of 545 children studied, 332 received a booster dose. The most common serotypes carried around the time of the first PCV7 dose were 6B (n = 37), 19F (n = 22), and 23F (n = 14). In carriers before the first dose, the IgG response to the carried serotype after 2 or 3 doses was significantly lower than in noncarriers. In contrast, response to the noncarried serotypes was not affected. Although all children responded to the booster dose, the response to the originally carried serotype was generally lower. Conclusions. Serotype-specific hyporesponsiveness to PCV7 after pneumococcal carriage in infants is demonstrated for the first time. This phenomenon was common, lasted for at least several months, and was only partially overcome by the 12-month booster. Trial registration. isrctn.org identifier: ISRCTN2844584
QASem Parsing: Text-to-text Modeling of QA-based Semantics
Several recent works have suggested to represent semantic relations with
questions and answers, decomposing textual information into separate
interrogative natural language statements. In this paper, we consider three
QA-based semantic tasks - namely, QA-SRL, QANom and QADiscourse, each targeting
a certain type of predication - and propose to regard them as jointly providing
a comprehensive representation of textual information. To promote this goal, we
investigate how to best utilize the power of sequence-to-sequence (seq2seq)
pre-trained language models, within the unique setup of semi-structured
outputs, consisting of an unordered set of question-answer pairs. We examine
different input and output linearization strategies, and assess the effect of
multitask learning and of simple data augmentation techniques in the setting of
imbalanced training data. Consequently, we release the first unified QASem
parsing tool, practical for downstream applications who can benefit from an
explicit, QA-based account of information units in a text
Subject-centered multi-view feature fusion for neuroimaging retrieval and classification
Multi-View neuroimaging retrieval and classification play an important role in computer-aided-diagnosis of brain disorders, as multi-view features could provide more insights of the disease pathology and potentially lead to more accurate diagnosis than single-view features. The large inter-feature and inter-subject variations make the multi-view neuroimaging analysis a challenging task. Many multi-view or multi-modal feature fusion methods have been proposed to reduce the impact of inter-feature variations in neuroimaging data. However, there is not much in-depth work focusing on the inter-subject variations. In this study, we propose a subject-centered multi-view feature fusion method for neuroimaging retrieval and classification based on the propagation graph fusion (PGF) algorithm. Two main advantages of the proposed method are: 1) it evaluates the query online and adaptively reshapes the connections between subjects according to the query; 2) it measures the affinity of the query to the subjects using the subject-centered affinity matrices, which can be easily combined and efficiently solved. Evaluated using a public accessible neuroimaging database, our algorithm outperforms the state-of-the-art methods in retrieval and achieves comparable performance in classification
Are Anticapsular Antibodies the Primary Mechanism of Protection against Invasive Pneumococcal Disease?
BACKGROUND: Antibody to capsular polysaccharide has been the basis of several vaccines that offer protection against invasive disease from Streptococcus pneumoniae. The success of such vaccines has led to the inference that natural protection against invasive pneumococcal disease is largely conferred by anticapsular antibody. If this is so, one would expect that the decline in disease from different serotypes would vary significantly, and that the appearance of substantial concentrations of anticapsular antibodies would coincide temporally with the decline in age-specific incidence. METHODS AND FINDINGS: Using incidence data from the United States, we show that, on the contrary, the decline in incidence with age is quite similar for the seven most important serogroups, despite large differences in exposure in the population. Moreover, only modest increases in antibody concentration occur over the second and third years of life, a period in which serotype-specific incidence declines to less than 25% of its peak. We also present detailed data on the distribution of antibody concentrations in Israeli toddlers, which are consistent with the United States findings. The same conclusion is supported by new data on age-specific incidence in Finland, which is compared with published data on antibody acquisition in Finnish toddlers. CONCLUSION: We suggest some additional studies of the mechanisms of protection that could distinguish among potential alternative mechanisms, including acquired immunity to noncapsular antigens, maturation of nonspecific immune responses, or changes in anatomy or exposure
Longitudinal brain MR retrieval with diffeomorphic demons registration: What happened to those patients with similar changes?
Current medical content-based retrieval (MCBR) systems for neuroimaging data mainly focus on retrieving the cross-sectional neuroimaging data with similar regional or global measurements. The longitudinal pathological changes along different time-points are usually neglected in such MCBR systems. We propose the cross-registration based retrieval for longitudinal MR data to retrieve patients with similar structural changes as an extension to the existing MCBR systems. The diffeomorphic demons registration is used to extract the tissue deformation between two adjacent MR volumes. An asymmetric square dissimilarity matrix is designed for indexing the patient changes within a specific interval. A visual demonstration is given to show the registration displacement fields of the query as compared to the simulated results. The experimental performance with the mean average precision (mAP) and the average top-K accuracy (aACC) are reported for evaluation
- …