ABSTRACT We performed geometric pulsar light curve modeling using static, retarded vacuum, and offset polar cap (PC) dipole B-fields (the latter is characterized by a parameter ϵ), in conjunction ...with standard two-pole caustic (TPC) and outer gap (OG) emission geometries. The offset-PC dipole B-field mimics deviations from the static dipole (which corresponds to ). In addition to constant-emissivity geometric models, we also considered a slot gap (SG) E-field associated with the offset-PC dipole B-field and found that its inclusion leads to qualitatively different light curves. Solving the particle transport equation shows that the particle energy only becomes large enough to yield significant curvature radiation at large altitudes above the stellar surface, given this relatively low E-field. Therefore, particles do not always attain the radiation-reaction limit. Our overall optimal light curve fit is for the retarded vacuum dipole field and OG model, at an inclination angle and observer angle . For this B-field, the TPC model is statistically disfavored compared to the OG model. For the static dipole field, neither model is significantly preferred. We found that smaller values of ϵ are favored for the offset-PC dipole field when assuming constant emissivity, and larger ϵ values favored for variable emissivity, but not significantly so. When multiplying the SG E-field by a factor of 100, we found improved light curve fits, with and ζ being closer to best fits from independent studies, as well as curvature radiation reaction at lower altitudes.
Abstract
We present results from a leptonic emission code that models the spectral energy distribution of a pulsar wind nebula by solving a Fokker–Planck-type transport equation and calculating ...inverse Compton and synchrotron emissivities. We have created this time-dependent, multizone model to investigate changes in the particle spectrum as they traverse the pulsar wind nebula, by considering a time and spatially dependent B-field, spatially dependent bulk particle speed implying convection and adiabatic losses, diffusion, as well as radiative losses. Our code predicts the radiation spectrum at different positions in the nebula, yielding the surface brightness versus radius and the nebular size as function of energy. We compare our new model against more basic models using the observed spectrum of pulsar wind nebula G0.9+0.1, incorporating data from H.E.S.S. as well as radio and X-ray experiments. We show that simultaneously fitting the spectral energy distribution and the energy-dependent source size leads to more stringent constraints on several model parameters.
Background
Food allergies can have serious physical, social, and financial consequences. This systematic review examined ways to prevent the development of food allergy in children and adults.
...Methods
Seven bibliographic databases were searched from their inception to September 30, 2012, for systematic reviews, randomized controlled trials, quasi‐randomized controlled trials, controlled clinical trials, controlled before‐and‐after studies, interrupted time series studies, and prospective cohort studies. Experts were consulted for additional studies. There were no language or geographic restrictions. Two reviewers appraised the studies using appropriate tools. Data were not suitable for meta‐analysis due to heterogeneity, so were narratively synthesized.
Results
Seventy‐four studies were included, one‐third of which were of high quality. There was no good evidence to recommend that pregnant or breastfeeding women should change their diet or take supplements to prevent allergies in infants at high or normal risk. There were mixed findings about the preventive benefits of breastfeeding for infants at high or normal risk, but there was evidence to recommend avoiding cow's milk and substituting with extensively or partially hydrolyzed whey or casein formulas for infants at high risk for the first 4 months. Soy milk and delaying the introduction of solid foods beyond 4 months did not have preventive benefits in those at high or normal risk. There was very little evidence about strategies for preventing food allergy in older children or adults.
Conclusions
There is much to learn about preventing food allergy, and this is a priority given the high societal and healthcare costs involved.
COSMIC-RAY POSITRONS FROM MILLISECOND PULSARS Venter, C.; Kopp, A.; Harding, A. K. ...
Astrophysical journal/The Astrophysical journal,
07/2015, Volume:
807, Issue:
2
Journal Article
Peer reviewed
Open access
ABSTRACT Observations by the Fermi Large Area Telescope of γ-ray millisecond pulsar (MSP) light curves imply copious pair production in their magnetospheres, and not exclusively in those of younger ...pulsars. Such pair cascades may be a primary source of Galactic electrons and positrons, contributing to the observed enhancement in positron flux above ∼10 GeV. Fermi has also uncovered many new MSPs, impacting Galactic stellar population models. We investigate the contribution of Galactic MSPs to the flux of terrestrial cosmic-ray electrons and positrons. Our population synthesis code predicts the source properties of present-day MSPs. We simulate their pair spectra invoking an offset-dipole magnetic field. We also consider positrons and electrons that have been further accelerated to energies of several TeV by strong intrabinary shocks in black widow (BW) and redback (RB) systems. Since MSPs are not surrounded by pulsar wind nebulae or supernova shells, we assume that the pairs freely escape and undergo losses only in the intergalactic medium. We compute the transported pair spectra at Earth, following their diffusion and energy loss through the Galaxy. The predicted particle flux increases for non-zero offsets of the magnetic polar caps. Pair cascades from the magnetospheres of MSPs are only modest contributors around a few tens of GeV to the lepton fluxes measured by the Alpha Magnetic Spectrometer, PAMELA, and Fermi, after which this component cuts off. The contribution by BWs and RBs may, however, reach levels of a few tens of percent at tens of TeV, depending on model parameters.
In 2014, the European Academy of Allergy and Clinical Immunology published prevalence estimates for food allergy (FA) and food sensitization (FS) to the so‐called eight big food allergens (i.e. cow's ...milk, egg, wheat, soy, peanut, tree nuts, fish and shellfish) in Europe for studies published between 2000 and 2012. The current work provides 10‐year updated prevalence estimates for these food allergens. A protocol was registered on PROSPERO before starting the research (reference number CRD42021266657). Six databases were searched for studies published 2012–2021, added to studies published up to 2012, resulting in a total of 93 studies. Most studies were graded as at moderate risk of bias. The overall pooled estimates for all age groups of self‐reported lifetime prevalence were as follows: cow's milk (5.7%, 95% confidence interval 4.4–6.9), egg (2.4%, 1.8–3.0), wheat (1.6%, 0.9–2.3), soy (0.5%, 0.3–0.7), peanut (1.5%, 1.0–2.1), tree nuts (0.9%, 0.6–1.2), fish (1.4%, 0.8–2.0) and shellfish (0.4%, 0.3–0.6). The point prevalence of food challenge‐verified allergy were as follows: cow's milk (0.3%, 0.1–0.5), egg (0.8%, 0.5–1.2), wheat (0.1%, 0.01–0.2), soy (0.3%, 0.1–0.4), peanut (0.1%, 0.0–0.2), tree nuts (0.04%, 0.02–0.1), fish (0.02%, 0.0–0.1) and shellfish (0.1%, 0.0–0.2). With some exceptions, the prevalence of allergy to common foods did not substantially change during the last decade; variations by European regions were observed.
An interesting new high-energy pulsar sub-population is emerging following early discoveries of gamma-ray millisecond pulsars (MSPs) by the Fermi Large Area Telescope (LAT). We present results from ...three-dimensional emission modeling, including the special relativistic effects of aberration and time-of-flight delays and also rotational sweepback of B-field lines, in the geometric context of polar cap (PC), outer gap (OG), and two-pole caustic (TPC) pulsar models. In contrast to the general belief that these very old, rapidly rotating neutron stars (NSs) should have largely pair-starved magnetospheres due to the absence of significant pair production, we find that most of the light curves are best fit by TPC and OG models, which indicates the presence of narrow accelerating gaps limited by robust pair production-even in these pulsars with very low spin-down luminosities. The gamma-ray pulse shapes and relative phase lags with respect to the radio pulses point to high-altitude emission being dominant for all geometries. We also find exclusive differentiation of the current gamma-ray MSP population into two MSP sub-classes: light curve shapes and lags across wavebands impose either pair-starved PC (PSPC) or TPC/OG-type geometries. In the first case, the radio pulse has a small lag with respect to the single gamma-ray pulse, while the (first) gamma-ray peak usually trails the radio by a large phase offset in the latter case. Finally, we find that the flux correction factor as a function of magnetic inclination and observer angles is typically of order unity for all models. Our calculation of light curves and flux correction factor for the case of MSPs is therefore complementary to the 'ATLAS paper' of Watters et al. for younger pulsars.
Abstract
We present 294 pulsars found in GeV data from the Large Area Telescope (LAT) on the Fermi Gamma-ray Space Telescope. Another 33 millisecond pulsars (MSPs) discovered in deep radio searches ...of LAT sources will likely reveal pulsations once phase-connected rotation ephemerides are achieved. A further dozen optical and/or X-ray binary systems colocated with LAT sources also likely harbor gamma-ray MSPs. This catalog thus reports roughly 340 gamma-ray pulsars and candidates, 10% of all known pulsars, compared to ≤11 known before Fermi. Half of the gamma-ray pulsars are young. Of these, the half that are undetected in radio have a broader Galactic latitude distribution than the young radio-loud pulsars. The others are MSPs, with six undetected in radio. Overall, ≥236 are bright enough above 50 MeV to fit the pulse profile, the energy spectrum, or both. For the common two-peaked profiles, the gamma-ray peak closest to the magnetic pole crossing generally has a softer spectrum. The spectral energy distributions tend to narrow as the spindown power
E
̇
decreases to its observed minimum near 10
33
erg s
−1
, approaching the shape for synchrotron radiation from monoenergetic electrons. We calculate gamma-ray luminosities when distances are available. Our all-sky gamma-ray sensitivity map is useful for population syntheses. The electronic catalog version provides gamma-ray pulsar ephemerides, properties, and fit results to guide and be compared with modeling results.
Successful skeletal muscle wound repair requires the alignment and fusion of myoblasts to generate multinucleated myofibers. In vitro, the accurate quantification of cellular alignment remains a ...challenge. Here we present the application of ImageJ and ct-FIRE to quantify muscle cell orientation by means of an alignment index (AI). Our optimised method, which does not require programming skills, allows the alignment of myoblasts in vitro to be determined independently of a predefined reference point. Using this method, we demonstrate that co-culture of myoblasts with macrophages, but not fibroblasts, promotes myoblast alignment in a cell density-dependent manner. Interestingly, myoblast fusion was significantly decreased in response to co-culture with macrophages, while the effect of fibroblasts on fusion was density-dependent. At lower numbers, fibroblasts significantly increased myoblast fusion, whereas at higher numbers a significant decrease was observed. Finally, triple co-culture revealed that the effect of macrophages on myoblast alignment and fusion is unaltered by the additional presence of fibroblasts. Application of our optimised method has therefore revealed quantitative differences in the roles of macrophages versus fibroblasts during alignment and fusion: while successful myoblast alignment is promoted by increasing macrophage numbers, regenerative fusion coincides with a decreasing macrophage population and initial rise in fibroblast numbers.
•We present a method for cellular alignment calculation during routine cell culture.•Application revealed that macrophages promote myoblast alignment, but delay fusion.•Furthermore, fibroblasts regulate myoblast fusion, but not alignment.•Effect of macrophages on alignment is not altered by co-culture with fibroblasts.
Summary
Background
While the prevalence of asthma in children is decreasing or remaining the same, time trends in the prevalence of rhinitis in children are not known. Understanding sensitisation ...trends may help inform about trends in asthma and rhinitis prevalence.
Objective
To assess time trends of wheeze, rhinitis and aero‐allergen sensitisation prevalence at 10 years of age, we compared two birth cohorts established 12 years apart. To gain insight into differences in disease prevalence, we assessed association of family history, early life exposures and sensitisation with wheeze and rhinitis in each cohort.
Methods
The IoW (Isle of Wight) and FAIR (Food Allergy and Intolerance Research) unselected birth cohorts were established in 1989 and 2001 respectively in IoW. Identical ISAAC questionnaire and skin prick test data were collected and compared at 10 years of age.
Results
Over the 12‐year period from 2001 to 2012, prevalence of lifetime wheeze, current wheeze and those ever treated for asthma decreased by 15.9% (45.5 vs. 29.6, P < 0.001), 3.9% (18.9 vs. 15, P = 0.020) and 8.2% (31.7 vs. 23.5, P = 0.001), respectively. Conversely, current rhinitis and lifetime rhinitis prevalence increased by 5.5% (22.6 vs. 28.1, P = 0.004) and 13% (18.6 vs. 31.7, P < 0.001), respectively. Atopic status remained stable; however, house dust mite (HDM) sensitisation decreased by 5.6% (19.2 vs. 13.6, P = 0.004) and grass sensitisation increased by 3.5% (12.9 vs. 16.4, P = 0.054). Male sex, parental history of asthma and HDM sensitisation were significantly associated with lifetime wheeze in both cohorts, while maternal smoking during pregnancy was a significant risk factor only in the earlier IoW cohort. Parental history of rhinitis and grass sensitisation was significantly associated with lifetime rhinitis in both cohorts, while HDM sensitisation was significant only for the IoW cohort.
Conclusion
Contrasting changes were noted with falling wheeze and HDM sensitisation but rising rhinitis and grass sensitisation prevalence. Changing prevalence of aero‐allergen sensitisations may explain the different time trends observed in these cohorts.
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