495 research outputs found
Rapidly rotating neutron stars: Universal relations and EOS inference
We provide accurate universal relations that allow to estimate the moment of
inertia and the ratio of kinetic to gravitational binding energy of
uniformly rotating neutron stars from the knowledge of mass, radius, and moment
of inertia of an associated non-rotating neutron star. Based on these, several
other fluid quantities can be estimated as well. Astrophysical neutron stars
rotate to varying degrees and although rotational effects may be neglected in
some cases, not modeling them will inevitably introduce bias when performing
parameter estimation. This is especially important for future, high-precision
measurements coming from electromagnetic and gravitational wave observations.
The proposed universal relations facilitate computationally cheap EOS inference
codes that permit the inclusion of observations of rotating neutron stars. To
demonstrate this, we deploy them into a recent Bayesian framework for equation
of state parameter estimation that is now valid for arbitrary, uniform
rotation. Our inference results are robust up to around percent level precision
for the generated neutron star observations, consisting of the mass, equatorial
radius, rotation rate, as well as co- and counter-rotating -mode
frequencies, that enter the framework as data.Comment: 16 pages, 14 figure
Neutron stars in Gauss-Bonnet gravity -- nonlinear scalarization and gravitational phase transitions
It was recently discovered that scalarized neutron stars in scalar-tensor
theories can undergo a gravitational phase transition to a non-scalarized (GR)
state. Surprisingly, even though the driving mechanism is totally different,
the process resembles closely the first-order matter phase transition from
confined nuclear matter to deconfined quark matter in neutron star cores. The
studies until now were limited, though, to only one theory of gravity and a
limited range of parameters. With the present paper, we aim at demonstrating
that gravitational phase transitions are more common than expected. More
specifically, we show that the phenomenon of nonlinear scalarization is present
for neutron stars in Gauss-Bonnet gravity leading to the possibility of
gravitational phase transition. Moreover, it can be observed for a wide range
of parameters so no fine-tuning is needed. This solidifies the conjecture that
gravitational phase transitions are an important phenomenon for compact objects
and their astrophysical implications deserve an in-depth study.Comment: 16 pages, 5 figure
A possible case of caprine-associated malignant catarrhal fever in a domestic water buffalo (Bubalus bubalis) in Switzerland
ABSTRACT: BACKGROUND: Malignant catarrhal fever (MCF) is a fatal herpesvirus infection, affecting various wild and domestic ruminants all over the world. Water buffaloes were reported to be particularly susceptible for the ovine herpesvirus-2 (OvHV-2) causing the sheep-associated form of MCF (SA-MCF). This report describes the first case of possibly caprine-associated malignant catarrhal fever symptoms in a domestic water buffalo in Switzerland. CASE PRESENTATION: The buffalo cow presented with persistent fever, dyspnoea, nasal bleeding and haematuria. Despite symptomatic therapy, the buffalo died and was submitted to post mortem examination. Major findings were an abomasal ulceration, a mild haemorrhagic cystitis and multifocal haemorrhages on the epicardium and on serosal and mucosal surfaces. Eyes and oral cavity were not affected. Histopathology revealed a mild to moderate lymphohistiocytic vasculitis limited to the brain and the urinary bladder. Although these findings are typical for MCF, OvHV-2 DNA was not detected in peripheral blood lymphocytes or in paraffin-embedded brain, using an OvHV-2 specific real time PCR. With the aid of a panherpesvirus PCR, a caprine herpesvirus-2 (CpHV-2) sequence could be amplified from both samples. CONCLUSIONS: To our knowledge, this is the first report of malignant catarrhal fever in the subfamily Bovinae, where the presence of CpHV-2 could be demonstrated. The etiological context has yet to be evaluated
Targeting human papillomavirus to reduce the burden of cervical, vulvar and vaginal cancer and pre-invasive neoplasia: establishing the baseline for surveillance.
Infection with high-risk human papillomavirus (HPV) is causally related to cervical, vulvar and vaginal pre-invasive neoplasias and cancers. Highly effective vaccines against HPV types 16/18 have been available since 2006, and are currently used in many countries in combination with cervical cancer screening to control the burden of cervical cancer. We estimated the overall and age-specific incidence rate (IR) of cervical, vulvar and vaginal cancer and pre-invasive neoplasia in Denmark, Iceland, Norway and Sweden in 2004-2006, prior to the availability of HPV vaccines, in order to establish a baseline for surveillance. We also estimated the population attributable fraction to determine roughly the expected effect of HPV16/18 vaccination on the incidence of these diseases
Field-free deterministic ultra fast creation of skyrmions by spin orbit torques
Magnetic skyrmions are currently the most promising option to realize
current-driven magnetic shift registers. A variety of concepts to create
skyrmions were proposed and demonstrated. However, none of the reported
experiments show controlled creation of single skyrmions using integrated
designs. Here, we demonstrate that skyrmions can be generated deterministically
on subnanosecond timescales in magnetic racetracks at artificial or natural
defects using spin orbit torque (SOT) pulses. The mechanism is largely similar
to SOT-induced switching of uniformly magnetized elements, but due to the
effect of the Dzyaloshinskii-Moriya interaction (DMI), external fields are not
required. Our observations provide a simple and reliable means for skyrmion
writing that can be readily integrated into racetrack devices
Streptomyces polyketides mediate bacteria–fungi interactions across soil environments
Although the interaction between prokaryotic and eukaryotic microorganisms is crucial for the functioning of ecosystems, information about the processes driving microbial interactions within communities remains scarce. Here we show that arginine-derived polyketides (arginoketides) produced by Streptomyces species mediate cross-kingdom microbial interactions with fungi of the genera Aspergillus and Penicillium, and trigger the production of natural products. Arginoketides can be cyclic or linear, and a prominent example is azalomycin F produced by Streptomyces iranensis, which induces the cryptic orsellinic acid gene cluster in Aspergillus nidulans. Bacteria that synthesize arginoketides and fungi that decode and respond to this signal were co-isolated from the same soil sample. Genome analyses and a literature search indicate that arginoketide producers are found worldwide. Because, in addition to their direct impact, arginoketides induce a secondary wave of fungal natural products, they probably contribute to the wider structure and functioning of entire soil microbial communities
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