Most stellar remnants so far have been found in binary systems, where they interact with matter from their companions. Isolated neutron stars and black holes are difficult to find as they are dark, ...yet they are predicted to exist in our Galaxy in vast numbers. We explored the OGLE-III data base of 150 million objects observed in years 2001–2009 and found 59 microlensing events exhibiting a parallax effect due to the Earth's motion around the Sun. Combining parallax and brightness measurements from microlensing light curves with expected proper motions in the Milky Way, we identified 13 microlensing events which are consistent with having a white dwarf, neutron star or a black hole lens and we estimated their masses and distances. The most massive of our black hole candidates has 9.3 M⊙ and is at a distance of 2.4 kpc. The distribution of masses of our candidates indicates a continuum in mass distribution with no mass gap between neutron stars and black holes. We also present predictions on how such events will be observed by the astrometric Gaia mission.
Aims. We report on the discovery and follow-up of a peculiar transient, OGLE17aaj, which occurred in the nucleus of a weakly active galaxy. We investigate whether it can be interpreted as a new ...candidate for a tidal disruption event (TDE). Methods. We present the OGLE-IV light curve that covers the slow 60-day-long rise to maximum along with photometric, spectroscopic, and X-ray follow-up during the first year. Results. OGLE17aaj is a nuclear transient exhibiting some properties similar to previously found TDEs, including a long rise time, lack of colour-temperature evolution, and high black-body temperature. On the other hand, its narrow emission lines and slow post-peak evolution are different from previously observed TDEs. Its spectrum and light-curve evolution is similar to F01004-2237 and AT 2017bgt. Signatures of historical low-level nuclear variability suggest that OGLE17aaj may instead be related to a new type of accretion event in active super-massive black holes.
We present an analytical study of two-dimensional flow in a wedge driven by a time-dependent surface heat flux as a model problem to understand buoyancy-induced cross-shore flow. Besides the ...turbulent Prandtl number and the relevant Rayleigh number, both assumed to be of order unity, the solution is seen to depend on the geometry through a parameter $\beta$, representing the bottom slope. An analytic solution is sought in the asymptotic limit $\beta \ll 1$ for a water layer bounded by an adiabatic bottom surface subject to a harmonic heat flux on the upper surface. The analysis reveals that the motion at leading order can be expressed as the sum of a harmonic component and a steady component, the latter driven by nonlinear advection. This steady-streaming motion includes a near-shore vortex with associated recirculating motion that can affect cross-shore transport and dispersion in coastal environments. The analytical solution is compared with numerical solutions of the complete conservation equations for small values of $\beta$. Excellent quantitative agreement is found for values of the Rayleigh number below a critical value at which the periodic solution undergoes a period-doubling bifurcation, leading to the establishment of thermal-instability cells that dominate the offshore flow dynamics, while the near-shore dynamics remains well described by the analytical solution. The analysis illustrates that a periodic heat input that leads to a vertically inhomogeneous temperature distribution can result in residual motion, net heat fluxes and persistent temperature structure in the cross-shore direction.
With increasing energy and resource consumption due to population growth, the biorefinery concept is becoming popular. This concept aims to harness all the properties of biomass by producing energy ...and recovering useful chemical products. Nutrients such as nitrogen and phosphorus play a key role in the world’s food production because they are the main elements used in fertilizer production. Hydrothermal carbonization (HTC) has been presented as a suitable option for energy recovery that can also be used as a pre-treatment for enhanced nutrient recovery. During the HTC process, part of the nitrogen and phosphorus are solubilized into the process water and the other part remains within the hydrochar. Hydrochars are mainly used as soil amendments due to their high content of phosphorus and nitrogen, but in this process, water still contains a considerable concentration of these compounds making it a potential source for their recovery. Therefore, HTC may boost the nutrient recovery strategy by extraction (process water) or densification (hydrochar) from biomass if it is coupled with another nutrient recovery process. This review presents an overview of the phosphorus and nitrogen fate during the HTC process from a perspective of nutrient recovery, presenting existing technologies and future trends.
•A critical review of HTC process for N and P recovery strategy is presented.•Different strategies of recovery of P and N using HTC are compared.•Detailed mechanisms of solubilization of P and N during HTC are described.•Reaction pathways involving P and N during HTC are outlined.•Existing technologies for P and N recovery are presented.
Large nonlinear internal solitary waves (NLIWs) are known to transit west northwest across the northeastern South China Sea from generation sites around the two‐ridge system in the Luzon Strait. The ...waves are important because their energy flux and dissipation are several orders of magnitude larger than the surrounding ocean. The wave transit has been well studied up to about the 100 m isobath but observations in shallower water have been scarce. Using oceanographic moorings and an innovative distributed temperature sensing optical cable, the NLIW transformations were observed from 2000 to 2 m on the flanks of Dongsha Atoll (Pratas Reef). Possible outcomes included reflection, refraction around the island, wave breaking, and penetration into shallow water. Upslope penetration depended on incident wave amplitude and direction as well as the local stratification.
Plain Language Summary
Because the ocean is stratified, it supports a wide range of internal waves in addition to the surface waves we observe all the time. Some of the largest such waves in the world, taller than the Washington Monument, are generated between Taiwan and the Philippines when the tide crashes into the underwater ridge system in the Luzon Strait. These “internal tides” continue to grow and steepen as they propagate west northwest across the South China Sea and eventually break forming the high frequency waves reported here. The waves are transformed as they enter shallower water surrounding a tropical reef, often splitting to form packets and ultimately breaking on the bottom much like surface waves do. Vertical currents surrounding the waves pump nutrients from the depths to the surface, nourishing the reef. The fate of the wave energy is complex and may be reflected, refracted, or dissipated on the reef.
Key Points
Shoaling nonlinear internal solitary waves were observed over three fortnights using moorings and an optical cable from 2000 m depth to the top of Dongsha Reef in the South China Sea
Packet formation was common from the 500 to 300 m isobaths but almost all waves broke by the time they reached 100 m depth and subsequently presented a turbulent, transformed wave runup environment
Possible outcomes are classified according to the wave type, incident wave amplitude, propagation direction, and ambient stratification
Psychiatric genetic counseling: A mapping exercise Moldovan, Ramona; McGhee, Kevin A.; Coviello, Domenico ...
American journal of medical genetics. Part B, Neuropsychiatric genetics,
December 2019, Letnik:
180, Številka:
8
Journal Article
Recenzirano
Psychiatric genetic counseling (PGC) is gradually developing globally, with countries in various stages of development. In some, PGC is established as a service or as part of research projects while ...in others, it is just emerging as a concept. In this article, we describe the current global landscape of this genetic counseling specialty and this field's professional development. Drawing on information provided by expert representatives from 16 countries, we highlight the following: (a) current understanding of PGC; (b) availability of services for patients; (c) availability of training; (d) healthcare system disparities and cultural differences impacting practice; and (e) anticipated challenges going forward.
The lifespan of a barotropic tidal eddy generated by flow around a coastal headland in deep (∼200 m) stratified water is examined. Field observations recorded the evolution of the flood tide eddy ...from its generation, through the eddy release at the turn of the tide, until its dissipation during subsequent tidal cycles. Ship‐based acoustic profiling reveals vortical structure that extends throughout the flow depth. Tracks from subsurface drifters from successive days indicated that flow structure was repeatable. Vorticity decay times, estimated from combined set of drifter tracks, are less than a tidal period. These are significantly shorter than simple estimates using boundary friction would imply, and it is suggested that baroclinic mechanisms associated with tilted vorticity in the deep stratified flow over the sloping headland may play a significant role in the dissipation of vorticity.
Background Hepcidin concentrations measured by various methods differ considerably, complicating interpretation. Here, a previously identified plasma-based candidate secondary reference material ...(csRM) was modified into a serum-based two-leveled sRM. We validated its functionality to increase the equivalence between methods for international standardization. Methods We applied technical procedures developed by the International Consortium for Harmonization of Clinical Laboratory Results. The sRM, consisting of lyophilized serum with cryolyoprotectant, appeared commutable among nine different measurement procedures using 16 native human serum samples in a first round robin (RR1). Harmonization potential of the sRM was simulated in RR1 and evaluated in practice in RR2 among 11 measurement procedures using three native human plasma samples. Comprehensive purity analysis of a candidate primary RM (cpRM) was performed by state of the art procedures. The sRM was value assigned with an isotope dilution mass spectrometry-based candidate reference method calibrated using the certified pRM. Results The inter-assay CV without harmonization was 42.1% and 52.8% in RR1 and RR2, respectively. In RR1, simulation of harmonization with sRM resulted in an inter-assay CV of 11.0%, whereas in RR2 calibration with the material resulted in an inter-assay CV of 19.1%. Both the sRM and pRM passed international homogeneity criteria and showed long-term stability. We assigned values to the low (0.95±0.11 nmol/L) and middle concentration (3.75±0.17 nmol/L) calibrators of the sRM. Conclusions Standardization of hepcidin is possible with our sRM, which value is assigned by a pRM. We propose the implementation of this material as an international calibrator for hepcidin.
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