Electrically charged particles can be created by the decay of strong enough electric fields, a phenomenon known as the Schwinger mechanism
. By electromagnetic duality, a sufficiently strong magnetic ...field would similarly produce magnetic monopoles, if they exist
. Magnetic monopoles are hypothetical fundamental particles that are predicted by several theories beyond the standard model
but have never been experimentally detected. Searching for the existence of magnetic monopoles via the Schwinger mechanism has not yet been attempted, but it is advantageous, owing to the possibility of calculating its rate through semi-classical techniques without perturbation theory, as well as that the production of the magnetic monopoles should be enhanced by their finite size
and strong coupling to photons
. Here we present a search for magnetic monopole production by the Schwinger mechanism in Pb-Pb heavy ion collisions at the Large Hadron Collider, producing the strongest known magnetic fields in the current Universe
. It was conducted by the MoEDAL experiment, whose trapping detectors were exposed to 0.235 per nanobarn, or approximately 1.8 × 10
, of Pb-Pb collisions with 5.02-teraelectronvolt center-of-mass energy per collision in November 2018. A superconducting quantum interference device (SQUID) magnetometer scanned the trapping detectors of MoEDAL for the presence of magnetic charge, which would induce a persistent current in the SQUID. Magnetic monopoles with integer Dirac charges of 1, 2 and 3 and masses up to 75 gigaelectronvolts per speed of light squared were excluded by the analysis at the 95% confidence level. This provides a lower mass limit for finite-size magnetic monopoles from a collider search and greatly extends previous mass bounds.
Abstract
Carbon monoxide (CO) provides crucial information about the molecular gas properties of galaxies. While 12CO has been targeted extensively, isotopologues such as 13CO have the advantage of ...being less optically thick and observations have recently become accessible across full galaxy discs. We present a comprehensive new data set of 13CO(1–0) observations with the IRAM 30-m telescope of the full discs of nine nearby spiral galaxies from the EMPIRE survey at a spatial resolution of ∼1.5 kpc. 13CO(1–0) is mapped out to 0.7 − 1 r25 and detected at high signal-to-noise ratio throughout our maps. We analyse the 12CO(1–0)-to-13CO(1–0) ratio (ℜ) as a function of galactocentric radius and other parameters such as the 12CO(2–1)-to-12CO(1–0) intensity ratio, the 70-to-160 μm flux density ratio, the star formation rate surface density, the star formation efficiency, and the CO-to-H2 conversion factor. We find that ℜ varies by a factor of 2 at most within and amongst galaxies, with a median value of 11 and larger variations in the galaxy centres than in the discs. We argue that optical depth effects, most likely due to changes in the mixture of diffuse/dense gas, are favoured explanations for the observed ℜ variations, while abundance changes may also be at play. We calculate a spatially resolved 13CO(1–0)-to-H2 conversion factor and find an average value of 1.0 × 1021 cm−2 (K km s−1)−1 over our sample with a standard deviation of a factor of 2. We find that 13CO(1–0) does not appear to be a good predictor of the bulk molecular gas mass in normal galaxy discs due to the presence of a large diffuse phase, but it may be a better tracer of the mass than 12CO(1–0) in the galaxy centres where the fraction of dense gas is larger.
Quantum jumps of a qubit are usually observed between its energy eigenstates, also known as its longitudinal pseudospin component. Is it possible, instead, to observe quantum jumps between the ...transverse superpositions of these eigenstates? We answer positively by presenting the first continuous quantum nondemolition measurement of the transverse component of an individual qubit. In a circuit QED system irradiated by two pump tones, we engineer an effective Hamiltonian whose eigenstates are the transverse qubit states, and a dispersive measurement of the corresponding operator. Such transverse component measurements are a useful tool in the driven-dissipative operation engineering toolbox, which is central to quantum simulation and quantum error correction.
The MoEDAL trapping detector consists of approximately 800 kg of aluminum volumes. It was exposed during run 2 of the LHC program to 6.46 fb^{-1} of 13 TeV proton-proton collisions at the LHCb ...interaction point. Evidence for dyons (particles with electric and magnetic charge) captured in the trapping detector was sought by passing the aluminum volumes comprising the detector through a superconducting quantum interference device (SQUID) magnetometer. The presence of a trapped dyon would be signaled by a persistent current induced in the SQUID magnetometer. On the basis of a Drell-Yan production model, we exclude dyons with a magnetic charge ranging up to five Dirac charges (5g_{D}) and an electric charge up to 200 times the fundamental electric charge for mass limits in the range 870-3120 GeV and also monopoles with magnetic charge up to and including 5g_{D} with mass limits in the range 870-2040 GeV.
Cardiomyopathy is an important cause of heart failure, however, there is notable lack of data on causes and manifestations of cardiomyopathy in Africa.
The African Cardiomyopathy and Myocarditis ...Registry Program (IMHOTEP) aims to address the knowledge gap on etiology, treatment, and outcomes of cardiomyopathy in sub-Saharan Africa.
We conducted a single-center pilot study to delineate the clinical and cardiovascular magnetic resonance (CMR) phenotypes of cardiomyopathy in South African patients. Assessment of the first 99 adult incident cases mean age 36.8 ± 12.5 years; females 53.5% enrolled in IMHOTEP showed that dilated cardiomyopathy (n = 77) was commonest, followed by hypertrophic (n = 13), restrictive (n = 5) and arrhythmogenic (n = 4) cardiomyopathies. A broad range of etiologies were encountered with secondary causes identified in 42% of patients. Onset of symptoms in the peripartum period was observed in 47% of women, and peripartum cardiomyopathy was diagnosed in 32.1% of women recruited. In addition to electrocardiography and echocardiography, CMR was performed in 67 cases and contributed diagnostically in a third of cases. Acute inflammation was rarely observed 2% on CMR, however, late gadolinium enhancement (LGE) was noted in 92% of cases.
We report a diverse spectrum of causes of cardiomyopathy in the South African population, with secondary, potentially treatable, etiologies in a significant proportion of cases. CMR was useful in delineating specific phenotypes and etiologies, influencing clinical care. A higher-than-expected burden of LGE was observed in this young patient cohort - the implications of which are yet to be determined.
•The IMHOTEP study represents the first step in addressing current knowledge deficits around cardiomyopathies in Africans.
•Secondary, potentially treatable, causes play an important role in development of dilated cardiomyopathy in South Africa.
•We observe a higher-than-expected burden of myocardial fibrosis in South African patients with cardiomyopathies.
Peripartum cardiomyopathy (PPCM) is an important cause of pregnancy-associated heart failure, which appears in previously healthy women towards the end of pregnancy or within five months following ...delivery. Although the ECG is widely used in clinical practice, its prognostic value has not been established in PPCM.
We analysed 12-lead ECGs of patients with PPCM, taken at index presentation and follow-up visits at 6 and 12 months. Poor outcome was determined by the composite endpoint of death, readmission, NYHA functional class III/IV or left ventricular ejection fraction (LVEF) of ≤35% at follow-up.
This cohort of 66 patients had a median age of 28.59 (IQR 25.43–32.19). The median LVEF at presentation (33%, IQR 25–40) improved significantly at follow-up (LVEF 49%, IQR 38–55, P < 0.001 at 6 months; 52% IQR 38–57, P = 0.001 at 12 months). Poor outcome occurred in 27.91% at 6 months and 41.18% at 1 year. Whereas sinus tachycardia at baseline was an independent predictor of poor outcome at 12 months (OR 6.56, 95% CI 1.17–20.41, P = 0.030), sinus arrhythmia was associated with event free survival (log rank P = 0.013). T wave inversion was associated with an LVEF ≤35% at presentation (P = 0.038), but did not predict poor outcome. A prolonged QTc interval at presentation (found in almost half of the cohort) was an independent predictor of poor outcome at 6 months (OR 6.34, 95% CI 1.06–37.80, P = 0.043).
A prolonged QTc and sinus tachycardia at baseline were independent predictors of poor outcome in PPCM at 6 months and 1 year respectively.
•ECG abnormalities are frequently encountered in patients with PPCM.•The ECG has a predictive value in PPCM.•Sinus arrhythmia is associated with a good outcome in PCCM.•Sinus tachycardia predicts poor outcome in PPCM.•A prolonged QTc at baseline is an independent predictor of poor outcome in PPCM.
AGN feedback in the nucleus of M51 Querejeta, M; Schinnerer, E; Garcia-Burillo, S ...
Astronomy and astrophysics (Berlin),
09/2016, Letnik:
593
Journal Article
Recenzirano
Odprti dostop
AGN feedback is invoked as one of the most relevant mechanisms that shape the evolution of galaxies. Our goal is to understand the interplay between AGN feedback and the interstellar medium in M51, a ...nearby spiral galaxy with a modest AGN and a kpc-scale radio jet expanding through the disc of the galaxy. For this purpose, we combine molecular gas observations in the CO(1-0) and HCN(1-0) lines from the Plateau de Bure interferometer with archival radio, X-ray, and optical data. We show that there is a significant scarcity of CO emission in the ionisation cone, while molecular gas emission tends to accumulate towards the edges of the cone. The distribution and kinematics of CO and HCN line emission reveal AGN feedback effects out to r~ 500 pc, covering the whole extent of the radio jet, with complex kinematics in the molecular gas which displays strong local variations. We propose that this is the result of the almost coplanar jet pushing on molecular gas in different directions as it expands; the effects are more pronounced in HCN than in CO emission, probably as the result of radiative shocks. Following previous interpretation of the redshifted molecular line in the central 5" as caused by a molecular outflow, we estimate the outflow rates to be M sub(H2)~ 0.9 M sub(middot in circle)/ yr and M sub(dense)~ 0.6 M sub(middot in circle)/ yr, which are comparable to the molecular inflow rates (~1 M sub(middot in circle)/ yr); gas inflow and AGN feedback could be mutually regulated processes. The agreement with findings in other nearby radio galaxies suggests that this is not an isolated case, and is probably the paradigm of AGN feedback through radio jets, at least for galaxies hosting low-luminosity active nuclei.
Summary Informed by the almost unimaginable unmet need for cardiac surgery in the developing regions of the world, leading surgeons, cardiologists, editors in chief of the major cardiothoracic ...journals as well as representatives of medical industry and government convened in December 2017 to address this unacceptable disparity in access to care. The ensuing “Cape Town Declaration” constituted a clarion call to cardiac surgical societies to jointly advocate the strengthening of sustainable, local cardiac surgical capacity in the developing world. The Cardiac Surgery Intersociety Alliance (CSIA) was thus created, comprising The Society of Thoracic Surgeons (STS), the American Association for Thoracic Surgery (AATS), the Asian Society for Cardiovascular and Thoracic Surgery (ASCVTS), the European Association for Cardio-Thoracic Surgery (EACTS) and the World Heart Federation (WHF). The guiding principle was advocacy for sustainable cardiac surgical capacity in low-income countries. As a first step, a global needs assessment confirmed rheumatic heart disease as the overwhelming pathology requiring cardiac surgery in these regions. Subsequently, CSIA published a request for proposals to support fledgling programmes that could demonstrate the backing by their governments and health care institution. Out of 11 applicants, and following an evaluation of the sites, including site visits to the 3 finalists, Mozambique and Rwanda were selected as the first Pilot Sites. Subsequently, a mentorship and training agreement was completed between Mozambique and the University of Cape Town, a middle-income country with a comparable burden of rheumatic heart disease. The agreement entails regular video calls between the heart teams, targeted training across all aspects of cardiac surgery, as well as on-site presence of mentoring teams for complex cases with the strict observance of ‘assisting only’. In Rwanda, Team Heart, a US and Rwanda-based non-governmental organization (NGO) that has been performing cardiac surgery in Rwanda and helping to train the cardiac surgery workforce since 2008, has agreed to continue providing mentorship for the local team and to assist in the establishment of independent cardiac surgery with all that entails. This involves intermittent virtual conferences between Rwandan and US cardiologists for surgical case selection. Five years after CSIA was founded, its ‘Seal of Approval’ for the sustainability of endorsed programmes in Mozambique and Rwanda has resulted in higher case numbers, a stronger government commitment, significant upgrades of infrastructure, the nurturing of generous consumable donations by industry and the commencement of negotiations with global donors for major grants. Extending the CSIA Seal to additional deserving programmes could further align the international cardiac surgical community with the principle of local cardiac surgery capacity-building in developing countries.
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