3,094 research outputs found

    Bayesian Analysis of Inflation III: Slow Roll Reconstruction Using Model Selection

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    We implement Slow Roll Reconstruction -- an optimal solution to the inverse problem for inflationary cosmology -- within ModeCode, a publicly available solver for the inflationary dynamics. We obtain up-to-date constraints on the reconstructed inflationary potential, derived from the WMAP 7-year dataset and South Pole Telescope observations, combined with large scale structure data derived from SDSS Data Release 7. Using ModeCode in conjunction with the MultiNest sampler, we compute Bayesian evidence for the reconstructed potential at each order in the truncated slow roll hierarchy. We find that the data are well-described by the first two slow roll parameters, \epsilon and \eta, and that there is no need to include a nontrivial \xi parameter.Comment: 14 pages, 12 figures, minor changes; final version; accepted in PR

    An Investigation into the Effect of Blood Flow Restriction on Pain and Muscular Endurance in Healthy Human Participants

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    Objective This study compared the effect of exercise during full, partial (intermittent) and no BFR on pain and muscular endurance. Design Within-subject repeated measures cross-over study comparing full BFR (200 mmHg), partial BFR (100 mmHg) and no (control) BFR during hand-grip exercises of a bulb dynamometer (60 per minute) at 30% of their one-repetition maximum of grip strength. Setting Laboratory. Participants 20 student volunteers (male = 14, age = 22-29 years). Main outcome measures Time to exhaustion and pain perception at minute intervals during handgrip exercises. Results There were fewer (77.0 ± 34.7) handgrip exercise repetitions during full BFR compared with partial BFR (125.1 ± 37.7, p < 0.001) and fewer repetitions for partial BFR compared with no BFR (147.6 ± 11.3 repetitions, p = 0.026). Pain intensity was higher for full BFR compared with partial BFR (p = 0.045) and higher for partial BFR compared with no BFR (p < 0.001). Participants selected more total, sensory and affective pain descriptors of the Short-Form McGill Pain Questionnaire during full BFR compared with partial BFR and no BFR. Conclusion Full BFR produced severe exercise-induced pain so partial BFR may be a more acceptable training and rehabilitation aid

    Acceleration of the Universe driven by the Casimir force

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    We investigate an evolutional scenario of the FRW universe with the Casimir energy scaling like ()(1+z)4(-)(1+z)^4. The Casimir effect is used to explain the vacuum energy differences (its value measured from astrophysics is so small compared to value obtained from quantum field theory calculations). The dynamics of the FRW model is represented in terms of a two-dimensional dynamical system to show all evolutional paths of this model in the phase space for all admissible initial conditions. We find also an exact solution for non flat evolutional paths of Universe driven by the Casimir effect. The main difference between the FRW model with the Casimir force and the Λ\LambdaCDM model is that their generic solutions are a set of evolutional paths with a bounce solution and an initial singularity, respectively. The evolutional scenario are tested by using the SNIa data, FRIIb radiogalaxies, baryon oscillation peak and CMB observation. We compare the power of explanation of the model considered and the Λ\LambdaCDM model using the Bayesian information criterion and Bayesian factor. Our investigation of the information criteria of model selection showed the preference of the Λ\LambdaCDM model over the model considered. However the presence of negative like the radiation term can remove a tension between the theoretical and observed primordial 4{}^4He and D abundance.Comment: RevTeX4, 17 pages, 9 figure

    Dynamic Behavior in Piezoresponse Force Microscopy

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    Frequency dependent dynamic behavior in Piezoresponse Force Microscopy (PFM) implemented on a beam-deflection atomic force microscope (AFM) is analyzed using a combination of modeling and experimental measurements. The PFM signal comprises contributions from local electrostatic forces acting on the tip, distributed forces acting on the cantilever, and three components of the electromechanical response vector. These interactions result in the bending and torsion of the cantilever, detected as vertical and lateral PFM signals. The relative magnitudes of these contributions depend on geometric parameters of the system, the stiffness and frictional forces of tip-surface junction, and operation frequencies. The dynamic signal formation mechanism in PFM is analyzed and conditions for optimal PFM imaging are formulated. The experimental approach for probing cantilever dynamics using frequency-bias spectroscopy and deconvolution of electromechanical and electrostatic contrast is implemented.Comment: 65 pages, 15 figures, high quality version available upon reques

    Genomic characterization of emerging bacterial uropathogen Neisseria meningitidis, which was misidentified as Neisseria gonorrhoeae by nucleic acid amplification testing

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    Neisseria meningitidis and Neisseria gonorrhoeae are pathogenic bacteria that can cause human infections. While N. meningitidis infections are associated with bacterial meningitis and bacteremia, a strain of N. meningitidis, isolated from the urogenital system, has recently been associated with urethritis. As this strain is becoming prominent as an emerging pathogen, it is essential to assess identification tools for N. meningitidis and N. gonorrhoeae urogenital isolates. Consecutive N. meningitidis isolates recovered from urogenital cultures of symptomatic patients with presumptive diagnoses of gonorrhea and a random selection of N. gonorrhoeae isolates recovered from the same population within the same time frame were characterized with routine identification systems, antimicrobial susceptibility testing, and whole-genome sequencing. Matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS), multilocus sequence typing, 16S rRNA gene sequence, and average nucleotide identity methods accurately identified 95% (18/19) of N. meningitidis and N. gonorrhoeae isolates. With the Aptima Combo 2 CT/NG test, 30% (3/10) of N. meningitidis isolates were misidentified as N. gonorrhoeae, but no misidentifications were found with the Xpert CT/NG nucleic acid amplification test (NAAT). Phylogenetic core genome and single nucleotide polymorphism (SNP)-based grouping analyses showed that urogenital N. meningitidis isolates were highly related and phylogenetically distinct from N. gonorrhoeae and respiratory N. meningitidis isolates but similar to urogenital N. meningitidis isolates from patients with urethritis in the United States. Urogenital N. meningitidis isolates were predominantly azithromycin resistant, while N. gonorrhoeae isolates were azithromycin susceptible. These data indicate that urogenital isolates of N. meningitidis can cause false-positive detections with N. gonorrhoeae diagnostic assays. Misidentification of urogenital N. meningitidis isolates may confound public health-related activities for gonorrhea, and future studies are needed to understand the impact on clinical outcome of N. meningitidis urogenital infection

    Antibiotic prophylaxis is associated with subsequent resistant infections in children with an initial extended-spectrum-cephalosporin-resistant Enterobacteriaceae infection

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    ABSTRACT The objective of this study was to assess the association between previous antibiotic use, particularly long-term prophylaxis, and the occurrence of subsequent resistant infections in children with index infections due to extended-spectrum-cephalosporin-resistant Enterobacteriaceae . We also investigated the concordance of the index and subsequent isolates. Extended-spectrum-cephalosporin-resistant Escherichia coli and Klebsiella spp. isolated from normally sterile sites of patients aged &lt;22 years were collected along with associated clinical data from four freestanding pediatric centers. Subsequent isolates were categorized as concordant if the species, resistance determinants, and fumC-fimH ( E. coli ) or tonB ( Klebsiella pneumoniae ) type were identical to those of the index isolate. In total, 323 patients had 396 resistant isolates; 45 (14%) patients had ≥1 subsequent resistant infection, totaling 73 subsequent resistant isolates. The median time between the index and first subsequent infections was 123 (interquartile range, 43 to 225) days. In multivariable Cox proportional hazards analyses, patients were 2.07 times as likely to have a subsequent resistant infection (95% confidence interval, 1.11 to 3.87) if they received prophylaxis in the 30 days prior to the index infection. In 26 (58%) patients, all subsequent isolates were concordant with their index isolate, and 7 (16%) additional patients had at least 1 concordant subsequent isolate. In 12 of 17 (71%) patients with E. coli sequence type 131 (ST131)-associated type 40-30, all subsequent isolates were concordant. Subsequent extended-spectrum-cephalosporin-resistant infections are relatively frequent and are most commonly due to bacterial strains concordant with the index isolate. Further study is needed to assess the role prophylaxis plays in these resistant infections. </jats:p

    Intense physical activity is associated with cognitive performance in the elderly

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    Numerous studies have reported positive impacts of physical activity on cognitive function. However, the majority of these studies have utilised physical activity questionnaires or surveys, thus results may have been influenced by reporting biases. Through the objective measurement of routine levels of physical activity via actigraphy, we report a significant association between intensity, but not volume, of physical activity and cognitive functioning. A cohort of 217 participants (aged 60–89 years) wore an actigraphy unit for 7 consecutive days and underwent comprehensive neuropsychological assessment. The cohort was stratified into tertiles based on physical activity intensity. Compared with individuals in the lowest tertile of physical activity intensity, those in the highest tertile scored 9%, 9%, 6% and 21% higher on the digit span, digit symbol, Rey Complex Figure Test (RCFT) copy and Rey Figure Test 30-min recall test, respectively. Statistically, participants in the highest tertile of physical activity intensity performed significantly better on the following cognitive tasks: digit symbol, RCFT copy and verbal fluency test (all P<0.05). The results indicate that intensity rather than quantity of physical activity may be more important in the association between physical activity and cognitive function

    Age and terminal reproductive attempt influence laying date in the Thorn‐tailed Rayadito

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    Age‐specific variation in reproductive effort can affect population dynamics, and is a key component of the evolution of reproductive tactics. Late‐life declines are a typical feature of variation in reproduction. However, the cause of these declines, and thus their implications for the evolution of life‐history tactics, may differ. Some prior studies have shown late‐life reproductive declines to be tied to chronological age, whereas other studies have found declines associated with terminal reproduction irrespective of chronological age. We investigated the extent to which declines in late life reproduction are related to chronological age, terminal reproductive attempt or a combination of both in the Thorn‐tailed Rayadito (Aphrastura spinicauda), a small passerine bird that inhabits the temperate forest of South America. To this end we used long‐term data (10 years) obtained on reproductive success (laying date, clutch size and nestling weight) of females in a Chilean population. Neither chronological age nor terminal reproductive attempt explained variation in clutch size or nestling weight, however we observed that during the terminal reproductive attempt older females tended to lay later in the breeding season and younger females laid early in the breeding season, but this was not the case when the reproductive attempt was not the last. These results suggests that both age‐dependent and age‐independent effects influence reproductive output and therefore that the combined effects of age and physiological condition may be more relevant than previously thought

    The Temporal Modulation Structure of Infant-Directed Speech

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    The temporal modulation structure of adult-directed speech (ADS) is thought to be encoded by neuronal oscillations in the auditory cortex that fluctuate at different temporal rates. Oscillatory activity is thought to phase-align to amplitude modulations in speech at corresponding rates, thereby supporting parsing of the signal into linguistically relevant units. The temporal modulation structure of infant-directed speech (IDS) is unexplored. Here we compare the amplitude modulation (AM) structure of IDS recorded from mothers speaking, over three occasions, to their 7-, 9-, and 11-month-old infants, and the same mothers speaking ADS. Analysis of the modulation spectrum in each case revealed that modulation energy in the theta band was significantly greater in ADS than in IDS, whereas in the delta band, modulation energy was significantly greater for IDS than ADS. Furthermore, phase alignment between delta- and theta-band AMs was stronger in IDS compared to ADS. This remained the case when IDS and ADS were rate-normalized to control for differences in speech rate. These data indicate stronger rhythmic synchronization and acoustic temporal regularity in IDS compared to ADS, structural acoustic differences that may be important for early language learningWe thank Maria Christou-Ergos for preparation of data for analysis. This work was supported by funding from the Australian Research Council (DP110105123) to DB and UG
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