619 research outputs found
Four ultra-short period eclipsing M-dwarf binaries in the WFCAM Transit Survey
We report on the discovery of four ultra-short period (P<0.18 days) eclipsing
M-dwarf binaries in the WFCAM Transit Survey. Their orbital periods are
significantly shorter than of any other known main-sequence binary system, and
are all significantly below the sharp period cut-off at P~0.22 days as seen in
binaries of earlier type stars. The shortest-period binary consists of two M4
type stars in a P=0.112 day orbit. The binaries are discovered as part of an
extensive search for short-period eclipsing systems in over 260,000 stellar
lightcurves, including over 10,000 M-dwarfs down to J=18 mag, yielding 25
binaries with P<0.23 days. In a popular paradigm, the evolution of short period
binaries of cool main-sequence stars is driven by loss of angular momentum
through magnetised winds. In this scheme, the observed P~0.22 day period
cut-off is explained as being due to timescales that are too long for
lower-mass binaries to decay into tighter orbits. Our discovery of low-mass
binaries with significantly shorter orbits implies that either these timescales
have been overestimated for M-dwarfs, e.g. due to a higher effective magnetic
activity, or that the mechanism for forming these tight M-dwarf binaries is
different from that of earlier type main-sequence stars.Comment: 22 pages, 17 figures, 3 tables Accepted for publication in MNRA
Management of pain in Fabry disease in the UK clinical setting: consensus findings from an expert Delphi panel
Background: Fabry disease is a rare, X-linked inherited lysosomal storage disorder, that manifests as a heterogeneous disease with renal, cardiac and nervous system involvement. The most common pain experienced by people with Fabry disease are episodes of neuropathic pain reported in up to 80% of classical hemizygous male patients and up to 65% of heterozygous female patients. No clear consensus exists within UK clinical practice for the assessment and management of pain in Fabry disease based on agreed clinical practice and clinical experience. Here we describe a modified Delphi initiative to establish expert consensus on management of pain in Fabry disease in the UK clinical setting. Methods: Delphi panel members were identified based on their demonstrated expertise in managing adult or paediatric patients with Fabry disease in the UK and recruited by an independent third-party administrator. Ten expert panellists agreed to participate in two survey rounds, during which they remained anonymous to each other. Circulation of the questionnaires, and collection and processing of the panel’s responses were conducted between September 2021 and December 2021. All questions required an answer. Results: The Delphi panel reached a consensus on 21 out of 41 aspects of pain assessment and management of pain in Fabry disease. These encompassed steps in the care pathway from the goals of therapy through to holistic support, including the use of gabapentin and carbamazepine as first-line analgesic medications for the treatment of neuropathic pain in Fabry disease, as well as the proactive management of symptoms of anxiety and/or depression associated with Fabry pain. Conclusions: The consensus panel outcomes reported here have highlighted strengths in current UK clinical practice, along with unmet needs for further research and agreement. This consensus is intended to prompt the next steps towards developing clinical guidelines
Thermal Decomposition Pathways of ZnxFe3- xO4Nanoparticles in Different Atmospheres
This article shows how initial composition and thermal treatment of nonstoichiometric zinc ferrite nanoparticles (nZFN) can be chosen to adjust the structure and cation distribution and enhance magnetism in the resulting nanoscale material. It also provides insight into new prospects regarding the production and design of nanoscale materials. Investigations were conducted before and after heating of nZFN in an inert atmosphere and a vacuum up to temperature of 1170 °C. Annealing leads to partial reduction of Fe ions, enhanced magnetism, and an increase in the size of the particles independent of the atmosphere. Use of the inert atmosphere delivers a solid solution of magnetite and zinc ferrite with a reduced Zn content in the structure as a result of sublimation of newly formed ZnO and reduction of Fe, and it favors crystallization. A preference for normal-spinel phase and enhancement of magnetic saturation from 20 Am2/kg up to 101 Am2/kg was observed. Vacuum annealing with high probability produces ZnO, Fe3O4, and Fe2O3 multiphase system with signs of amorphization, mainly on the surface. A large fraction of Fe ions is reduced and the volume ratio of Fe3O4 to Fe2O3 increases with heating time. The final solid product from a complete decomposition of ZFN is magnetite
Longitudinal Analysis of Quality of Life, Clinical, Radiographic, Echocardiographic, and Laboratory Variables in Dogs with Preclinical Myxomatous Mitral Valve Disease Receiving Pimobendan or Placebo: The EPIC Study
Background: Changes in clinical variables associated with the administration of pimobendan to dogs with preclinical myxomatous mitral valve disease (MMVD) and cardiomegaly have not been described.
Objectives: To investigate the effect of pimobendan on clinical variables and the relationship between a change in heart size and the time to congestive heart failure (CHF) or cardiac-related death (CRD) in dogs with MMVD and cardiomegaly. To determine whether pimobendan-treated dogs differ from dogs receiving placebo at onset of CHF.
Animals: Three hundred and fifty-four dogs with MMVD and cardiomegaly.
Materials and Methods: Prospective, blinded study with dogs randomized (ratio 1:1) to pimobendan (0.4-0.6 mg/kg/d) or placebo. Clinical, laboratory, and heart-size variables in both groups were measured and compared at different time points (day 35 and onset of CHF) and over the study duration. Relationships between short-term changes in echocardiographic variables and time to CHF or CRD were explored.
Results: At day 35, heart size had reduced in the pimobendan group:median change in (Delta) LVIDDN -0.06 (IQR:-0.15 to + 0.02), P < 0.0001, and LA:Ao -0.08 (IQR:-0.23 to + 0.03), P < 0.0001. Reduction in heart size was associated with increased time to CHF or CRD. Hazard ratio for a 0.1 increase in Delta LVIDDN was 1.26, P = 0.0003. Hazard ratio for a 0.1 increase in Delta LA:Ao was 1.14, P = 0.0002. At onset of CHF, groups were similar.
Conclusions and Clinical Importance: Pimobendan treatment reduces heart size. Reduced heart size is associated with improved outcome. At the onset of CHF, dogs treated with pimobendan were indistinguishable from those receiving placebo
X-rays in the Orion Nebula Cluster: Constraints on the origins of magnetic activity in pre-main sequence stars
A recent Chandra/ACIS observation of the Orion Nebula Cluster detected 1075
sources (Feigelson et al. 2002), providing a uniquely large and well-defined
sample to study the dependence of magnetic activity on bulk properties for
stars descending the Hayashi tracks. The following results are obtained: (1)
X-ray luminosities L_t in the 0.5-8 keV band are strongly correlated with
bolometric luminosity with = -3.8 for stars with masses 0.7<M<2
Mo, an order of magnitude below the main sequence saturation level; (2) the
X-ray emission drops rapidly below this level in some or all stars with 2<M<3
Mo; (3) the presence or absence of infrared circumstellar disks has no apparent
relation to X-ray levels; and (4) X-ray luminosities exhibit a slight rise as
rotational periods increase from 0.4 to 20 days. This last finding stands in
dramatic contrast to the strong anticorrelation between X-rays and period seen
in main sequence stars.
The absence of a strong X-ray/rotation relationship in PMS stars, and
particularly the high X-ray values seen in some very slowly rotating stars, is
a clear indication that the mechanisms of magnetic field generation differ from
those operating in main sequence stars. The most promising possibility is a
turbulent dynamo distributed throughout the deep convection zone, but other
models such as alpha-Omega dynamo with `supersaturation' or relic core fields
are not immediately excluded. The drop in magnetic activity in
intermediate-mass stars may reflect the presence of a significant radiative
core. The evidence does not support X-ray production in large-scale star-disk
magnetic fields.Comment: 51 pages, 8 figures. To appear in the Astrophysical Journa
Effect of Pimobendan in Dogs with Preclinical Myxomatous Mitral Valve Disease and Cardiomegaly: The EPIC Study - A Randomized Clinical Trial
Background: Pimobendan is effective in treatment of dogs with congestive heart failure (CHF) secondary to myxomatous mitral valve disease (MMVD). Its effect on dogs before the onset of CHF is unknown. Hypothesis/Objectives: Administration of pimobendan (0.4-0.6 mg/kg/d in divided doses) to dogs with increased heart size secondary to preclinical MMVD, not receiving other cardiovascular medications, will delay the onset of signs of CHF, cardiac-related death, or euthanasia. Animals: 360 client-owned dogs with MMVD with left atrial-to-aortic ratio >= 1.6, normalized left ventricular internal diameter in diastole >= 1.7, and vertebral heart sum >10.5. Methods: Prospective, randomized, placebo-controlled, blinded, multicenter clinical trial. Primary outcome variable was time to a composite of the onset of CHF, cardiac-related death, or euthanasia. Results: Median time to primary endpoint was 1228 days (95% CI: 856-NA) in the pimobendan group and 766 days (95% CI: 667-875) in the placebo group (P = .0038). Hazard ratio for the pimobendan group was 0.64 (95% CI: 0.47-0.87) compared with the placebo group. The benefit persisted after adjustment for other variables. Adverse events were not different between treatment groups. Dogs in the pimobendan group lived longer (median survival time was 1059 days (95% CI: 952-NA) in the pimobendan group and 902 days (95% CI: 747-1061) in the placebo group) (P = .012). Conclusions and Clinical Importance: Administration of pimobendan to dogs with MMVD and echocardiographic and radiographic evidence of cardiomegaly results in prolongation of preclinical period and is safe and well tolerated. Prolongation of preclinical period by approximately 15 months represents substantial clinical benefit
Fundamental Parameters of He-Weak and He-Strong Stars
We carried out low resolution spectroscopic observations in the wavelength
range 3400-4700 A of 20 He-weak and 8 He-strong stars to determine their
fundamental parameters by means of the Divan-Chalonge-Barbier (BCD)
spectrophotometric system. For a few He-weak stars we also estimate the
effective temperatures and the angular diameters by integrating absolute fluxes
observed over a wide spectral range. Non-LTE model calculations are carried out
to study the influence of the He/H abundance ratio on the emergent radiation of
He-strong stars and on their Teff determination. We find that the effective
temperatures, surface gravities and bolometric absolute magnitudes of He-weak
stars estimated with the BCD system and the integrated flux method are in good
agreement between each other, and they also agree with previous determinations
based on several different methods. The mean discrepancy between the visual
absolute magnitudes derived using the Hipparcos parallaxes and the BCD values
is on average 0.3 mag for He-weak stars, while it is 0.5 mag for He-strong
stars. For He-strong stars, we note that the BCD calibration, based on stars in
the solar environment, leads to overestimated values of Teff. By means of model
atmosphere calculations with enhanced He/H abundance ratios we show that larger
He/H ratios produce smaller BD which naturally explains the Teff
overestimation. We take advantage of these calculations to introduce a method
to estimate the He/H abundance ratio in He-strong stars. The BD of HD 37479
suggests that the Teff of this star remains fairly constant as the star
spectrum undergoes changes in the intensity of H and He absorption lines. Data
for the He-strong star HD 66765 are reported for the first time.Comment: Accepted for publication in A&
Spin states of zigzag-edged Mobius graphene nanoribbons from first principles
Mobius graphene nanoribbons have only one edge topologically. How the
magnetic structures, previously associated with the two edges of zigzag-edged
flat nanoribbons or cyclic nanorings, would change for their Mobius
counterparts is an intriguing question. Using spin-polarized density functional
theory, we shed light on this question. We examine spin states of zigzag-edged
Mobius graphene nanoribbons (ZMGNRs) with different widths and lengths. We find
a triplet ground state for a Mobius cyclacene, while the corresponding
two-edged cyclacene has an open-shell singlet ground state. For wider ZMGNRs,
the total magnetization of the ground state is found to increase with the
ribbon length. For example, a quintet ground state is found for a ZMGNR. Local
magnetic moments on the edge carbon atoms form domains of majority and minor
spins along the edge. Spins at the domain boundaries are found to be
frustrated. Our findings show that the Mobius topology (i.e., only one edge)
causes ZMGNRs to favor one spin over the other, leading to a ground state with
non-zero total magnetization.Comment: 17 pages, 4 figure
Advances in chemical and biological methods to identify microorganisms—from past to present
Fast detection and identification of microorganisms is a challenging and significant feature from industry to medicine. Standard approaches are known to be very time-consuming and labor-intensive (e.g., culture media and biochemical tests). Conversely, screening techniques demand a quick and low-cost grouping of bacterial/fungal isolates and current analysis call for broad reports of microorganisms, involving the application of molecular techniques (e.g., 16S ribosomal RNA gene sequencing based on polymerase chain reaction). The goal of this review is to present the past and the present methods of detection and identification of microorganisms, and to discuss their advantages and their limitations.C.F.R. would like to thank the Portuguese Foundation for Science and Technology (FCT–Portugal) for the C.F.R. for the project UID/EQU/00511/2019—Laboratory for Process Engineering, Environment, Biotechnology, and Energy—LEPABE funded by national funds through FCT/MCTES (PIDDAC) and N.M. for the Strategic project ref. UID/BIM/04293/2013 and “NORTE2020 - Programa Operacional Regional do Norte” (NORTE-01-0145-FEDER-000012)
Effect of surface chemistry and associated protein corona on the long-term biodegradation of iron oxide nanoparticles in Vivo
The protein corona formed on the surface of a nanoparticle in a biological medium determines its behavior in vivo. Herein, iron oxide nanoparticles containing the same core and shell, but bearing two different surface coatings, either glucose or poly(ethylene glycol), were evaluated. The nanoparticles' protein adsorption, in vitro degradation, and in vivo biodistribution and biotransformation over four months were investigated. Although both types of nanoparticles bound similar amounts of proteins in vitro, the differences in the protein corona composition correlated to the nanoparticles biodistribution in vivo. Interestingly, in vitro degradation studies demonstrated faster degradation for nanoparticles functionalized with glucose, whereas the in vivo results were opposite with accelerated biodegradation and clearance of the nanoparticles functionalized with poly(ethylene glycol). Therefore, the variation in the degradation rate observed in vivo could be related not only to the molecules attached to the surface, but also with the associated protein corona, as the key role of the adsorbed proteins on the magnetic core degradation has been demonstrated in vitro
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