This study reports on the accuracy of smartphone sound measurement applications (apps) and whether they can be appropriately employed for occupational noise measurements. A representative sample of ...smartphones and tablets on various platforms were acquired, more than 130 iOS apps were evaluated but only 10 apps met our selection criteria. Only 4 out of 62 Android apps were tested. The results showed two apps with mean differences of 0.07 dB (unweighted) and -0.52 dB (A-weighted) from the reference values. Two other apps had mean differences within ±2 dB. The study suggests that certain apps may be appropriate for use in occupational noise measurements.
Compact, tunable, radially symmetric focusing of electrons is critical to laser-plasma accelerator (LPA) applications. Experiments are presented demonstrating the use of a discharge-capillary active ...plasma lens to focus 100-MeV-level LPA beams. The lens can provide tunable field gradients in excess of 3000 T/m, enabling cm-scale focal lengths for GeV-level beam energies and allowing LPA-based electron beams and light sources to maintain their compact footprint. For a range of lens strengths, excellent agreement with simulation was obtained.
The largest glitch observed in the Crab pulsar Shaw, B; Lyne, A G; Stappers, B W ...
Monthly Notices of the Royal Astronomical Society,
08/2018, Letnik:
478, Številka:
3
Journal Article
The glitch activity of neutron stars Fuentes, J. R.; Espinoza, C. M.; Reisenegger, A. ...
Astronomy & astrophysics,
12/2017, Letnik:
608
Journal Article
Recenzirano
Odprti dostop
We present a statistical study of the glitch population and the behaviour of the glitch activity across the known population of neutron stars. An unbiased glitch database was put together based on ...systematic searches of radio timing data of 898 rotation-powered pulsars obtained with the Jodrell Bank and Parkes observatories. Glitches identified in similar searches of 5 magnetars were also included. The database contains 384 glitches found in the rotation of 141 of these neutron stars. We confirm that the glitch size distribution is at least bimodal, with one sharp peak at approximately 20 μHz, which we call large glitches, and a broader distribution of smaller glitches. We also explored how the glitch activity ν̇g, defined as the mean frequency increment per unit of time due to glitches, correlates with the spin frequency ν, spin-down rate |ν̇|, and various combinations of these, such as energy loss rate, magnetic field, and spin-down age. It is found that the activity is insensitive to the magnetic field and that it correlates strongly with the energy loss rate, though magnetars deviate from the trend defined by the rotation-powered pulsars. However, we find that a constant ratio ν̇g/|ν̇| = 0.010 ± 0.001 is consistent with the behaviour of all rotation-powered pulsars and magnetars. This relation is dominated by large glitches, which occur at a rate directly proportional to |ν̇|. For low |ν̇|, only small glitches have been detected, making the inferred glitch activity formally lower than that predicted by the constant ratio, in many cases zero. However, we can attribute this to the low predicted rate for large glitches, together with the insufficient observing time, which makes it unlikely to detect any large glitches in this range. Taking this into consideration, we show that the behaviour of each rotation-powered pulsar and magnetar is statistically consistent with the above relationship, including those objects where no glitches have been detected so far. The only exception are the rotation-powered pulsars with the highest values of |ν̇|, such as the Crab pulsar and PSR B0540−69, which exhibit a much smaller glitch activity, intrinsically different from each other and from the rest of the population. The activity due to small glitches also shows an increasing trend with |ν̇|, but this relation is biased by selection effects.
ABSTRACT
We present updated measurements of the Crab pulsar glitch of 2019 July 23 using a data set of pulse arrival times spanning ∼5 months. On MJD 58687, the pulsar underwent its seventh largest ...glitch observed to date, characterized by an instantaneous spin-up of ∼1 μHz. Following the glitch, the pulsar’s rotation frequency relaxed exponentially towards pre-glitch values over a time-scale of approximately 1 week, resulting in a permanent frequency increment of ∼0.5 μHz. Due to our semicontinuous monitoring of the Crab pulsar, we were able to partially resolve a fraction of the total spin-up. This delayed spin-up occurred exponentially over a time-scale of ∼18 h. This is the sixth Crab pulsar glitch for which part of the initial rise was resolved in time and this phenomenon has not been observed in any other glitching pulsars, offering a unique opportunity to study the microphysical processes governing interactions between the neutron star interior and the crust.
Unraveling the macroevolutionary history of bryophytes, which arose soon after the origin of land plants but exhibit substantially lower species richness than the more recently derived angiosperms, ...has been challenged by the scarce fossil record. Here we demonstrate that overall estimates of net species diversification are approximately half those reported in ferns and ∼30% those described for angiosperms. Nevertheless, statistical rate analyses on time-calibrated large-scale phylogenies reveal that mosses and liverworts underwent bursts of diversification since the mid-Mesozoic. The diversification rates further increase in specific lineages towards the Cenozoic to reach, in the most recently derived lineages, values that are comparable to those reported in angiosperms. This suggests that low diversification rates do not fully account for current patterns of bryophyte species richness, and we hypothesize that, as in gymnosperms, the low extant bryophyte species richness also results from massive extinctions.
Mammalian studies have raised concerns about the toxicity of carbon nanotubes (CNTs), but there is very limited data on ecotoxicity to aquatic life. We describe the first detailed report on the ...toxicity of single walled carbon nanotubes (SWCNT) to rainbow trout, using a body systems approach. Stock solutions of dispersed SWCNT were prepared using a combination of solvent (sodium dodecyl sulphate, SDS) and sonication. A semi-static test system was used to expose rainbow trout to either a freshwater control, solvent control, 0.1, 0.25 or 0.5
mg
l
−1 SWCNT for up to 10 days. SWCNT exposure caused a dose-dependent rise in ventilation rate, gill pathologies (oedema, altered mucocytes, hyperplasia), and mucus secretion with SWCNT precipitation on the gill mucus. No major haematological or blood disturbances were observed in terms of red and white blood cell counts, haematocrits, whole blood haemoglobin, and plasma Na
+ or K
+. Tissue metal levels (Na
+, K
+, Ca
2+, Cu, Zn and Co) were generally unaffected. However some dose-dependent changes in brain and gill Zn or Cu were observed (but not tissue Ca
2+), that were also partly attributed to the solvent. SWCNT exposure caused statistically significant increases in Na
+K
+-ATPase activity in the gills and intestine, but not in the brain. Thiobarbituric acid reactive substances (TBARS) showed dose-dependent and statistically significant decreases especially in the gill, brain and liver during SWCNT exposure compared to controls. SWCNT exposure caused statistically significant increases in the total glutathione levels in the gills (28%) and livers (18%), compared to the solvent control. Total glutathione in the brain and intestine remained stable in all treatments. Pathologies in the brain included possible aneurisms or swellings on the ventral surface of the cerebellum. Liver cells exposed to SWCNT showed condensed nuclear bodies (apoptotic bodies) and cells in abnormal nuclear division. Overt fatty change or wide spread lipidosis was absent in the liver. Fish ingested water containing SWCNT during exposure (presumably stress-induced drinking) which resulted in precipitated SWCNT in the gut lumen and intestinal pathology. Aggressive behaviour and fin nipping caused some mortalities at the end of the experiment, which may be associated with the gill irritation and brain injury, although the solvent may also partly contributed to aggression. Overall we conclude that SWCNTs are a respiratory toxicant in trout, the fish are able to manage oxidative stress and osmoregulatory disturbances, but other cellular pathologies raise concerns about cell cycle defects, neurotoxicity, and as yet unidentified blood borne factors that possibly mediate systemic pathologies.
Hematopoietic stem cell transplant (HCT) recipients have a substantial risk of developing secondary solid cancers, particularly beyond 5 years after HCT and without reaching a plateau overtime. A ...working group was established through the Center for International Blood and Marrow Transplant Research and the European Group for Blood and Marrow Transplantation with the goal to facilitate implementation of cancer screening appropriate to HCT recipients. The working group reviewed guidelines and methods for cancer screening applicable to the general population and reviewed the incidence and risk factors for secondary cancers after HCT. A consensus approach was used to establish recommendations for individual secondary cancers. The most common sites include oral cavity, skin, breast and thyroid. Risks of cancers are increased after HCT compared with the general population in skin, thyroid, oral cavity, esophagus, liver, nervous system, bone and connective tissues. Myeloablative TBI, young age at HCT, chronic GVHD and prolonged immunosuppressive treatment beyond 24 months were well-documented risk factors for many types of secondary cancers. All HCT recipients should be advised of the risks of secondary cancers annually and encouraged to undergo recommended screening based on their predisposition. Here we propose guidelines to help clinicians in providing screening and preventive care for secondary cancers among HCT recipients.
More than 100 different mutations in the gene encoding copper-zinc superoxide dismutase (SOD1) cause familial forms of amyotrophic lateral sclerosis (ALS) – a fatal neurodegenerative disease in which ...aggregation of the SOD1 protein is considered to be the primary mode of pathogenesis. Recent results show that these mutations have remarkably diverse and unexpected effects on the structure, activity and native state stability of SOD1. Intriguingly, many mutations seem to have no measurable effect on the biophysical and biochemical properties of SOD1, except for decreasing the net charge of the protein. Thus, it seems likely that different ALS-associated mutations promote SOD1 aggregation by fundamentally distinct mechanisms. Understanding this complexity has implications for drug development and treatment of the disease.
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