4,794 research outputs found
A dynamic relationship between mucosal T helper type 17 and regulatory T-cell populations in nasopharynx evolves with age and associates with the clearance of pneumococcal carriage in humans
Pneumococcal carriage is common in young children, which may account for the high incidence of disease in this age group. Host factors determining the clearance of carriage in humans remain unclear. We aimed to study the relationships between T helper type 17 (Th17) and Foxp3(+) regulatory T (Treg) cells in nasopharynx-associated lymphoid tissue (NALT) and carriage in children and adults. Frequencies of Th17 and Treg cells in NALT were analysed by flow cytometry in association with age and pneumococcal carriage status. Cytokine responses following pneumococcal stimulation were analysed by cytometric beads array. The frequencies of Th17 and Treg cells in NALT were inversely correlated (R -0.60). Whereas Treg cell frequency decreased with age (R -0.63), both Th17 and the Th17: Treg ratio increased with age (R 0.62 and R 0.64, respectively). Also, the Th17: Treg ratio was higher in carriage-negative than in carriage-positive children (p <0.01). Pneumococcal stimulation of tonsillar cells increased both Th17 and Treg cell numbers, but the Th17: Treg ratio and pattern of cytokine responses differed between carriage-negative and carriage-positive children. The former showed markedly higher Th17: Treg and interleukin-17A: interleukin-10 ratios than in the latter (p <0.01). Pneumococcal stimulation also induces Th17, although the capacity of this Th17 differentiation from naive T cells of young children was low, but increased with age. We demonstrated a dynamic relationship between Th17 and Treg cells in human nasopharynx that evolves with age. The balance between Th17 and Treg cells in NALT appears to be a major host factor closely associated with the clearance of Streptococcus pneumoniae from the nasopharynx
Spectrally Efficient WDM Nyquist Pulse-Shaped Subcarrier Modulation Using a Dual-Drive Mach-Zehnder Modulator and Direct Detection
High data transmission capacity is increasingly needed in shortand medium-haul optical communication links. Cost-effective wavelength division multiplexed (WDM) transceiver architectures, achieving high information spectral densities (ISDs) (>1 b/s/Hz) and using low-complexity direct detection receivers are attractive solutions for such links. In this paper, we assess the use of dual-drive Mach-Zehnder modulators (DD-MZMs), and compare them with in-phase quadrature (IQ)-modulators for generating spectrally-efficient single sideband Nyquist pulse-shaped 16-QAM subcarrier (N-SCM) modulation format signals. The impact of the extinction ratio (ER) of a modulator on the optical sideband suppression ratio (OSSR) was investigated for the SSB signals in WDM systems, together with the resulting impact on inter-channel crosstalk penalties. First, in back-to-back operation, an IQ-modulator with an ER of 30 dB and a DD-MZM with an ER of 18 dB were experimentally compared in a 6×25 Gb/s WDM system by varying the channel spacing. Following this comparison, 16 GHz-spaced 6×25 Gb/s WDM signal transmission was experimentally demonstrated using the DD-MZM. The experiment was performed using a recirculating loop with uncompensated standard single-mode fiber (SSMF) and EDFA-only amplification. The maximum achievable transmission distances for single channel and WDM signals were found to be 565 and 242 km, respectively, at a net optical ISD of 1.5 b/s/Hz. This is the first experimental comparison of such modulator types for SSB N-SCM signal generation and the highest achieved ISD using a DD-MZM in direct-detection WDM transmission
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How Student Generated Peer-Assessment Rubrics use Affective Criteria to Evaluate Teamwork
Student generated rubrics that were designed to peer assess contribution to
teamwork mainly use terms that conform to Krathwohl’s (1964) affective domain. We
have used the affective domain to map the criteria that students use in order to find
opportunities to further guide our development and scaffolding of teamwork skills. We
are confident that our students are valuing skills within the affective domain as an
important contribution to teamwork, but we find that they are making tacit
assumptions about the lowest level of the domain – receiving skills. We aim to use
this data to support the conscious development of receiving skills, with the aim of
promoting team integration
Laboratory Studies of Feeding and Oviposition Preference, Developmental Performance, and Survival of the Predatory Beetle, Sasajiscymnus tsugae on Diets of the Woolly Adelgids, Adelges tsugae and Adelges piceae
The suitability of the balsam woolly adelgid, Adelges piceae Ratzeburg (Hemiptera: Adelgidae) as an alternate mass rearing host for the adelgid predator, Sasajiscymnus tsugae Sasaji and McClure (Coleoptera: Coccinellidae) was studied in the laboratory. This predator is native to Japan and has been introduced to eastern hemlock, Tsuga canadensis (L.) Carrière (Pinales: Pinaceae), forests throughout the eastern United States for biological control of the hemlock woolly adelgid, Adelges tsugae Annand (Hemiptera: Adelgidae), also of Japanese origin. Feeding, oviposition, immature development, and adult long-term survival of S. tsugae were tested in a series of no choice (single-prey) and paired-choice experiments between the primary host prey, A. tsugae, and the alternate host prey, A. piceae. In paired-choice feeding tests, the predator did not discriminate between eggs of the two adelgid species, but in the no choice tests the predator did eat significantly more eggs of A. piceae than those of A. tsugae. S. tsugae accepted both test prey for oviposition and preferred to lay eggs on adelgid infested versus noninfested host plants. Overall oviposition rates were very low (< 1 egg per predator female) in the oviposition preference tests. Predator immature development rates did not differ between the two test prey, but only 60% of S. tsugae survived egg to adult development when fed A. piceae compared to 86% when fed A. tsugae. S. tsugae adult long-term survival was significantly influenced (positively and negatively) by prey type and the availability of a supplemental food source (diluted honey) when offered aestivating A. tsugae sistens nymphs or ovipositing aestivosistens A. piceae adults, but not when offered ovipositing A. tsugae sistens adults. These results suggest that the development of S. tsugae laboratory colonies reared on a diet consisting only of A. piceae may be possible, and that the biological control potential of the predator might be expanded to include management of A. piceae in Christmas tree plantations
Can a falling tree make a noise in two forests at the same time?
It is a commonplace to claim that quantum mechanics supports the old idea
that a tree falling in a forest makes no sound unless there is a listener
present. In fact, this conclusion is far from obvious. Furthermore, if a
tunnelling particle is observed in the barrier region, it collapses to a state
in which it is no longer tunnelling. Does this imply that while tunnelling, the
particle can not have any physical effects? I argue that this is not the case,
and moreover, speculate that it may be possible for a particle to have effects
on two spacelike separate apparatuses simultaneously. I discuss the measurable
consequences of such a feat, and speculate about possible statistical tests
which could distinguish this view of quantum mechanics from a ``corpuscular''
one. Brief remarks are made about an experiment underway at Toronto to
investigate these issues.Comment: 9 pp, Latex, 3 figs, to appear in Proc. Obsc. Unr. Conf.; Fig 2
postscript repaired on 26.10.9
Revealing a signaling role of phytosphingosine-1-phosphate in yeast
Perturbing metabolic systems of bioactive sphingolipids with genetic approachMultiple types of “omics” data collected from the systemSystems approach for integrating multiple “omics” informationPredicting signal transduction information flow: lipid; TF activation; gene expressio
Traumatic thoracic ASIA A examinations and potential for clinical trials
Study Design: Retrospective review of prospective database
Objectives: To define the variability of neurologic examination and recovery after non-penetrating complete thoracic spinal cord injuries (ASIA A).
Background Data: Neurologic examinations after SCI can be difficult and inconsistent. Unlike cervical SCI patients, alterations in thoracic (below T1) complete SCI (ASIA A – based on the ASIA Impairment Scale [AIS]) patients’ exams are based only on sensory testing, thus changes in the neurological level (NL) are determined only by sensory changes.
Methods: A retrospective review of the placebo control patients in a multicenter prospective database utilized for the pharmacologic trial of Sygen. Patients were included if they had a complete thoracic SCI on initial evaluation, with completed ASIA examinations at follow-up weeks 4, 8, 16, 26 and 52. Specifically, pin prick (PP) and light touch (LT) were assessed and the absolute change was calculated as the number of spinal levels at a given observation time. Results 3165 patients were initially screened for the Sygen clinical trial, of which 57 were the control placebo patients used in this analysis. Alterations from the baseline exam (PP and LT) were fairly consistent and the median change/recovery in neurologic examination was one spinal level. Across all observations post-baseline, the average change for PP was 1.48 +/- 0.13 (mean +/- SE), and for LT, 1.40 +/-0.13. There were equal proportions of directional changes (none, improved, lost).
Conclusions: Changes in a thoracic complete (ASIA A) SCI patient ASIA examination as measured through sensory modalities (PP/LT) are fairly uncommon. The overall examination had only 1-2 level variability across patients, indicating minimal change in the sensory exam over the follow-up period. Stability in the ASIA examination as measured through sensory modalities has thus been demonstrated over time, making it an excellent tool to monitor changes in neurologic function
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