To send content items to your account,
please confirm that you agree to abide by our usage policies.
If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account.
Find out more about sending content to .
To send content items to your Kindle, first ensure email@example.com
is added to your Approved Personal Document E-mail List under your Personal Document Settings
on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part
of your Kindle email address below.
Find out more about sending to your Kindle.
Note you can select to send to either the @free.kindle.com or @kindle.com variations.
‘@free.kindle.com’ emails are free but can only be sent to your device when it is connected to wi-fi.
‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.
Growth in the immediate postnatal period for extremely low birth weight (ELBW, birth weight < 1000 g) infants is an important topic in neonatal medicine. The goal is to ensure adequate postnatal growth and to minimize complications resulting from suboptimal growth. Past efforts have focused on postnatal nutrition as well as on minimizing comorbidities. It has not been systematically assessed whether antenatal factors play a role in postnatal growth. In this report, we conducted a retrospective study on 91 maternal–neonatal pairs. We prospectively collected maternal and neonatal demographic data, neonatal nutrition in the first 7 days of life and after enteral nutrition is fully established, comorbidity data, as well as weight data from birth to 50 weeks corrected gestational age. We developed a linear mixed-effects model to examine the role of placental insufficiency, as defined by fetal Doppler studies, in postnatal weight z-score trajectory over time in the ELBW population. We relied on Akaike Information Criterion (AIC) and Bayesian Information Criterion (BIC) for model selection. Interestingly, the selected model included a quadratic term of time and a placental insufficiency-by-time interaction term. In a covariate analysis, AIC and BIC both favored a model that included calories intake in the first 7 days of life and the total duration of antibiotics as fixed-effects, but not their interaction terms with time. Overall, we demonstrated for the first time that placental insufficiency, an antenatal factor, is a major determinant of postnatal weight trajectory in the ELBW population. Prospective studies are warranted to confirm our findings.
We investigated strain relaxation in (001) InGaAs/GaAs structures using both double and triple axis high resolution x-ray diffraction techniques. We determined diat broadening which is observed in double axis scans stews pnmanly from mosaic spread and not from lattice constant variations in the layer, demonstrating that relaxation is uniform along the growth direction. These observations held for layers with both low and high indium content and extents of relaxation. Triple axis measurements showed that the peak broadening was due exclusively to mosaic spread for the low indium content samples and also confirmed earlier double axis measurements that a crystallographic tilt of the epitaxial layer was attributed to substrate miscut. The ability to distinguish the source of peak broadening and crystallographic tilts makes triple axis diffraction a powerful characterization technique for the study of mismatched epitaxial layers.
Here we present the synthesis of porous platinum–palladium macrobeams templated from high aspect ratio Magnus’ salt needle derivatives. The combination of [PtCl4]2− and/or [PdCl4]2− with [Pt(NH3)4]2+ ions results in salt needles ranging from 15 to 300 µm in length. Electrochemical reduction of the salt templates results in porous macrobeams with a square cross-section. Porous side wall texture and elemental composition was controlled with initial platinum to palladium salt ratio. Macrobeam free-standing films exhibited a specific capacitance up to 11.73 F/g and a solvent accessible surface area of 26.6 m2/g. These salt-templated porous platinum–palladium macrobeams offer a promising material for fuel cell catalysis.
Piglets are characteristically cold intolerant and thus susceptible to high mortality. However, browning of white adipose tissue (WAT) can induce non-shivering thermogenesis as a potential strategy to facilitate the animal’s response to cold. Whether cold exposure can induce browning of subcutaneous WAT (sWAT) in piglets in a similar manner as it can in humans remains largely unknown. In this study, piglets were exposed to acute cold (4°C, 10 h) or chronic cold exposure (8°C, 15 days), and the genes and proteins of uncoupling protein 1 (UCP1)-dependent and independent thermogenesis, mitochondrial biogenesis, lipogenic and lipolytic processes were analysed. Interestingly, acute cold exposure induced browning of porcine sWAT, smaller adipocytes and the upregulated expression of UCP1, PGC1α, PGC1β, C/EBPβ, Cidea, UCP3, CKMT1 and PM20D1. Conversely, chronic cold exposure impaired the browning process, reduced mitochondrial numbers and the expression of browning markers, including UCP1, PGC1α and PRDM16. The present study demonstrated that acute cold exposure (but not chronic cold exposure) induces porcine sWAT browning. Thus, browning of porcine sWAT could be a novel strategy to balance the body temperature of piglets, and thus could be protective against cold exposure.
GLOBALink, a large online network of tobacco control professionals, was active in the promotion of the World Health Organization's Framework Convention on Tobacco Control treaty, an international treaty aimed at reducing the global burden of tobacco-related death and disease. We examined and compared the roles that different countries served in the GLOBALink community during FCTC negotiation and ratification. Previous studies of FCTC ratification found the process adhered to a diffusion of innovation model (Valente et al., 2015). We followed that work by conducting content analyses of discussion messages posted by GLOBALink members representing different countries. Based on the time when they ratified the FCTC, each country was labeled by one of the four adoption stages of the diffusion model and we investigated the amount of shared word use between the different stages. A goodness-of-fit chi-squared test indicated that content was not shared in an expected manner between stages (χ2 = 11,856.45, N = 51,447, p < 0.001). A deeper look at the specific words shared between countries within and between adoption stages provided insight into how interactions between certain countries might have served to support the ratification process.
Increased mass losses from the Greenland ice sheet and inferred contributions to sea-level rise have heightened the need for hydrologic observations of meltwater exiting the ice sheet. We explore whether temporal variations in ice-sheet surface hydrology can be linked to the development of a downstream sediment plume in Kangerlussuaq Fjord by comparing: (1) plume area and suspended sediment concentration from Moderate Resolution Imaging Spectroradiometer (MODIS) imagery and field data; (2) ice-sheet melt extent from Special Sensor Microwave/Imager (SSM/I) passive microwave data; and (3) supraglacial lake drainage events from MODIS. Results confirm that the origin of the sediment plume is meltwater release from the ice sheet. Interannual variations in plume area reflect interannual variations in surface melting. Plumes appear almost immediately with seasonal surface-melt onset, provided the estuary is free of landfast sea ice. A seasonal hysteresis between melt extent and plume area suggests late-season exhaustion in sediment supply. Analysis of plume sensitivity to supraglacial events is less conclusive, with 69% of melt pulses and 38% of lake drainage events triggering an increase in plume area. We conclude that remote sensing of sediment plume behavior offers a novel tool for detecting the presence, timing and interannual variability of meltwater release from the ice sheet.
Based upon the Shliomis ferromagnetic fluid model and the Stokes microcontinuum theory incorporating with the Christensen stochastic model, a modified Reynolds equation of centrosymmetric squeeze films has been derived in this paper. The Reynolds equation includes the combined effects of non-Newtonian rheology, magnetic fluids with applied magnetic fields, rotational inertia forces, and surface roughness. To guide the use of the derived equation, the squeeze film of rotational rough-surface circular disks lubricated with non-Newtonian magnetic fluids is illustrated. According to the results obtained, the effects of rotation inertia decrease the load capacity and the squeeze film time of smooth circular disks. By the use of non-Newtonian magnetic fluids with applied magnetic fields, the rotational circular disks predict better squeeze film performances. When the influences of circumferential roughness patterns are considered, the non-Newtonian magnetic-fluid lubricated rotational rough disks with applied magnetic fields provide further higher values of the load capacity and the squeeze film time as compared to those of the smooth case.
The fast stellar winds can blow bubbles in the circumstellar material ejected from previous phases of stellar evolution. These are found at different scales, from planetary nebulae (PNe) around stars evolving to the white dwarf stage, to Wolf-Rayet (WR) bubbles and up to large-scale bubbles around massive star clusters. In all cases, the fast stellar wind is shock-heated and a hot bubble is produced. Processes of mass evaporation and mixing of nebular material and heat conduction occurring at the mixing layer between the hot bubble and the optical nebula are key to determine the thermal structure of these bubbles and their evolution. In this contribution we review our current understanding of the X-ray observations of hot bubbles in PNe and present the first spatially-resolved study of a mixing layer in a PN.
Magnetic Fields are the crucial and most important ingredient involved in the processes of various violent activities in Active Galactic Nuclei and other celestial bodies. The generally accepted 2-sided symmetric-jets model of active galactic nuclei (AGN) does not include the magnetic fields. We present here the first direct detection of helical magnetic field in AGN, and the first direct detection of ejection of large scale magnetic fields from AGN. (CME) 2. The annular (helical) magnetic field is responsible for the collimation of the jet (through Pinch Effect) and may be of crucial importance for extraction of black hole rotational energy. 3. The CMEs are responsible for sporadic ejection of jet components in AGN, while the general accepted 2-sided jets pertain to the quiescent Jets. 4. Observations show that the CME with Asymmetric Jets can explain many phenomena and much of the morphological diversities in AGN.
We present results from new HST imaging and spectroscopy of the peculiar Large Magellanic Cloud H II region N 44C and its ionizing star. While this nebula exhibits strong He II recombination emission, the source of the He+ ionizing photons has not been found. The UV spectrum of the ionizing star suggests an approximate spectral class of 07–08; the UV Si IV, He II, and N IV features do not show P-Cygni profiles, indicating that the ionizing star is not a supergiant. No companion star has yet been detected. Ground-based and HST optical spectroscopy of the ionized gas shows that the nebular abundances of C, N, O and He are not anomalous relative to other LMC H II regions, suggesting that no previous WR/SN companion has disappeared. Echelle spectroscopy has also ruled out the presence of high velocity shocked gas. Deep ROSAT imaging shows no X-ray point source in this location. The “fossil X-ray binary” hypothesis of Pakull & Motch (1989) remains the best explanation for the ionization of this nebula; however, convincing evidence for this hypothesis remains elusive.
LMC2 was one of the first supergiant shells in the Large Magellanic Cloud (LMC) to be identified, based on the detection of long, curved Hα filaments extending over 900 pc (Goudis & Meaburn 1978). LMC 2 is located to the east of the active star formation region south of 30 Doradus. LMC 2 is a spectacular supergiant shell in the LMC, having the most coherent filamentary structure and the highest X-ray surface brightness. As shown in Fig. 1, the diffuse X-ray emission from LMC 2 is bounded by the Hα filaments in the north and east. A bright X-ray arc is seen in the southwest quadrant, extending from N 158 and N 159.
We analyze optical, radio and X-ray data from supernova remnants (SNRs) in the Large Magellanic Cloud (LMC) in order to make a systematic study of a full sample at a known distance. By this multiwavelength examination of SNRs from various progenitors and environments, we will build a comprehensive picture of the evolution of SNR structure and energetics.
Introduction: A novel bladder stimulation technique has been described for midstream urine (MSU) collection in well-feeding, inpatient newborns. We sought to determine the performance of this technique amongst infants presenting to the Emergency Department (ED). Methods: Our prospective ED-based study enrolled a convenience cohort of infants aged ≤ 90 days who required urine testing. Infants with significant feeding issues, moderate to severe dehydration, or critical illness were excluded. Bladder stimulation consisted of finger tapping on the lower abdomen with or without lower back massage while holding the child upright. Healthcare providers received standardized training in the technique. Primary outcome was the proportion of infants with successful MSU collection via the technique. Success was defined as adequate sample collection (≥ 1 mL urine) within 5 minutes of initiating stimulation. Secondary outcomes included the proportion of contaminated MSU samples, time required for MSU collection and full protocol completion, and patient discomfort as perceived by parent/guardian using a 100 mm visual analog scale [VAS]. Assuming success a priori in 50% of infants, a sample size of 115 allowed a 95% confidence interval of +/- 9.1% around the point estimate. Results: We enrolled 115 infants. Mean age was 53.0 days old (interquartile range [IQR] 26.7-68.0); 58.3% were male (69.2% uncircumcised). Midstream urine was successfully collected in 61 infants (53.0%; 95% CI 0.44,0.62). Thirty-one MSU samples (50.8%) were contaminated; uncircumcised males held the highest proportion (55.0%). Most contaminated samples (83.9%) were reported as “non-significant growth” or “growth of ≥ 3 organisms” and were easily identifiable as contaminants with minimal impact on clinical care. Only 4 (8.5%) of the 47 patients discharged home after successful MSU collection had a repeat ED visit for urine testing. Median stimulation time for MSU collection was 45 seconds (IQR 20-99 secs). Median time for full protocol completion was 30.83 minutes (IQR 24.42-46.83 mins). Mean VAS for infant discomfort was 20.2 mm (SD +/- 20.4 mm). Conclusion: Our pragmatic, ED-based study found the success rate of this bladder stimulation technique to be significantly lower (53%) than its published rate (86%). The contamination rate was high but most contaminated specimens were easily identifiable as such and had minimal clinical impact.
Cosmology is one of the most dynamically evolving areas of astrophysics today. Twenty years ago the estimates of the amplitude of the primordial fluctuations were about 10-3, almost a factor of 100 off of today’s measurements. Ten years ago we could only hope for high precision measurements of large scale structure, there were less than 5000 redshifts measured, and only a handful of normal galaxies with z > 1 were known. Computer models of structure formation had just begun to consider non-power-law spectra based on physical models like hot/cold dark matter. As a consequence there was considerable freedom in adjusting parameters in the various galaxy formation scenarios. In contrast, many of today’s debates are about factors of 2 and soon we will be arguing about 10% differences. The Harrison-Zeldovich shape of the primordial fluctuation spectrum, first derived from philosophical arguments can now be quantified from detections of fluctuations by COBE. The number of available redshifts is beyond 50,000, and soon we will have redshift surveys surpassing 1 million galaxies. N-body simulations are becoming more sophisticated, of higher resolution, and incorporating complex gas dynamics.
The orthodox model of active galactic nuclei (AGN), as is generally accepted, is that of Rees. We have found an AGN (3C 147) which has a counter-jet much longer than the main jet. It also has an unusual sideways ejection from the nuclear region. Both of these and the 3-jet structure per se do not seem to conform with the general accepted model, and are also not explained by relativistic beaming effects. We speculate that this is due to coronal mass ejection (CME) in the accretion disk corona. Recently, we have found convincing new evidence that this is true. We have also found direct evidence of helical magnetic fields in the core region of 3C 147. These results may be of importance to the understanding of AGN.