Where May Ultra-Fast Rotating Neutron Stars Be Hidden?

The existence of ultra-fast rotating neutron stars (spin period P < 1 ms) is expected on the basis of current models for the secular evolution of interacting binaries, though they have not been detected yet. Their formation depends on the quantity of matter accreted by the neutron star which, in turn, is limited by the mechanism of mass ejection from the binary. An efficient mass ejection can avoid the formation of ultra-fast pulsars or their accretion induced collapse to a black hole. We propose that significant reductions of the mass-transfer rate may cause the switch-on of a radio pulsar phase, whose radiation pressure may be capable of ejecting out of the system most of the matter transferred by the companion. This can prevent, for long orbital periods and if a sufficiently fast spin has been reached, any further accretion, even if the original transfer rate is restored, thus limiting the minimum spin period attainable by the neutron star. We show that close systems (orbital periods P_orb \sim 1 hr are the only possible hosts for ultra-fast spinning neutron stars. This could explain why ultra-fast radio pulsars have not been detected so far, as the detection of pulsars with very short spin periods in close systems is hampered, in current radio surveys, by strong Doppler modulation and computational limitations.Comment: 6 pages, including 1 figure. To appear in ApJ

Localisation of gamma-ray bursts from the combined SpIRIT+HERMES-TP/SP nano-satellite constellation

Multi-messenger observations of the transient sky to detect cosmic explosions and counterparts of gravitational wave mergers critically rely on orbiting wide-FoV telescopes to cover the wide range of wavelengths where atmospheric absorption and emission limit the use of ground facilities. Thanks to continuing technological improvements, miniaturised space instruments operating as distributed-aperture constellations are offering new capabilities for the study of high energy transients to complement ageing existing satellites. In this paper we characterise the performance of the upcoming joint SpIRIT + HERMES-TP/SP nano-satellite constellation for the localisation of high-energy transients through triangulation of signal arrival times. SpIRIT is an Australian technology and science demonstrator satellite designed to operate in a low-Earth Sun-synchronous Polar orbit that will augment the science operations for the equatorial HERMES-TP/SP. In this work we simulate the improvement to the localisation capabilities of the HERMES-TP/SP when SpIRIT is included in an orbital plane nearly perpendicular (inclination = 97.6$^\circ$) to the HERMES orbits. For the fraction of GRBs detected by three of the HERMES satellites plus SpIRIT, the combined constellation is capable of localising 60% of long GRBs to within ~ 30 deg$^2$ on the sky, and 60% of short GRBs within ~ 1850 deg$^2$. Based purely on statistical GRB localisation capabilities (i.e., excluding systematic uncertainties and sky coverage), these figures for long GRBs are comparable to those reported by the Fermi GBM. Further improvements by a factor of 2 (or 4) can be achieved by launching an additional 4 (or 6) SpIRIT-like satellites into a Polar orbit, which would both increase the fraction of sky covered by multiple satellite elements, and enable $\geq$ 60% of long GRBs to be localised within a radius of ~ 1.5$^\circ$ on the sky.Comment: 17 pages, 10 figures, 1 table. Accepted for publication in PAS

Autonomous management and control of sensor network-based applications

Paper presented at the 2nd International Workshop on Adaptation in Wireless Sensor Networks (AWSN-09), in conjunction with The 7th IEEE/IFIP International Conference on Embedded and Ubiquitous Computing (EUC 2009), August 29 - 31, 2009, Vancouver, CanadaA central challenge facing sensor network research and development is the difficulty in providing effective autonomous management capability. This is due to a large number of parameters to control, unexpected changes of the network topology and dynamic application requirements. Network management is also a challenging task for the remote user due to the large-scale of the network and scarce visibility of live network happenings. Preferably the network should have autonomous decision-making capabilities as network conditions and application requirements changes. To cope with such uncertainties, firstly we consider Octopus, a powerful software tool that provides live information about the network topology and sensor data. At present, the tool can provide monitoring and require a user to control the network state manually. This paper describes how Octopus is reengineered to accommodate a multi-agent system to provide autonomic managing capabilities. In particular, we detail two distinct architectures, the static and mobile agent architectures, which can be effectively applied to deliver autonomous system management. This paper sets the basis for a full autonomous network management via a multi agent system to work with Octopus.Science Foundation IrelandConference detailshttp://tweb.ing.unipi.it/awsn09

Antibiotics for urethral catheterization in children undergoing cystography: retrospective evaluation of a single-center cohort of pediatric non-toilet-trained patients

Antibiotics are often used to prevent post-catheterization urinary tract infections (UTIs) in patients undergoing cystography. However, there is no universally accepted protocol and the literature data are conflicting. We aimed to determine prevalence and risk factors of post-cystography UTIs in non-toilet-trained children. We retrospectively evaluated 216 non-toilet-trained children not assuming antibiotics when undergoing cystography. Only the patients with dilated vesico-ureteral reflux (VUR) assumed antibiotics just after the exam (within 15 min). One hundred eleven patients without vesico-ureteral reflux (VUR) and 29 patients with non-dilated VUR did not receive post-procedure antibiotics and did not develop UTIs. Out of the 76 patients who showed a dilated VUR and received post-procedure antibiotics, only 5 (6.6%) developed a UTI. The most significant factor associated with post-cystography UTIs was the presence of dilated VUR (p = 0.005) with the presence of bilateral VUR also being significant (p = 0.02). Conclusion: Patients without dilated VUR or bilateral VUR could not benefit from antibiotic prophylaxis for cystography.What is Known:• There is no universally accepted protocol about antibiotic administration in children undergoing cystography.• Literature data are conflicting.What is New:• Among 216 non-toilet-trained children undergoing cystography, 111 patients without vesico-ureteral reflux (VUR) and 29 patients with non-dilated VUR did not receive post-procedure antibiotics and did not develop UTIs. Out of the 76 patients who showed a dilated VUR and received post-procedure antibiotics, only 5 (6.6%) developed a UTI.• The most significant factor associated to post-cystography UTIs was the presence of dilated VUR (p = 0.005) with presence of bilateral VUR also being significant (p = 0.02)

A novel anti-GD2/4-1BB chimeric antigen receptor triggers neuroblastoma cell killing

Chimeric antigen receptor (CAR)-expressing T cells are a promising therapeutic option for patients with cancer. We developed a new CAR directed against the disialoganglioside GD2, a surface molecule expressed in neuroblastoma and in other neuroectoderm-derived neoplasms. The anti-GD2 single-chain variable fragment (scFv) derived from a murine antibody of IgM class was linked, via a human CD8\u3b1 hinge-transmembrane domain, to the signaling domains of the costimulatory molecules 4-1BB (CD137) and CD3-\u3b6. The receptor was expressed in T lymphocytes by retroviral transduction and anti-tumor activities were assessed by targeting GD2-positive neuroblastoma cells using in vitro cytotoxicity assays and a xenograft model. Transduced T cells expressed high levels of anti-GD2 CAR and exerted a robust and specific anti-tumor activity in 4- and 48-hour cultures with neuroblastoma cells. Cytotoxicity was associated with the release of pro-apoptotic molecules such as TRAIL and IFN-\u3b3. These results were confirmed in a xenograft model, where anti-GD2 CAR T cells infiltrating tumors and persisting into blood circulation induced massive apoptosis of neuroblastoma cells and completely abrogated tumor growth. This anti-GD2 CAR represents a powerful new tool to redirect T cells against GD2. The preclinical results of this study warrant clinical testing of this approach in neuroblastoma and other GD2-positive malignancies

Safety of Monoclonal Antibodies in Children Affected by SARS-CoV-2 Infection

Monoclonal antibody therapies for COVID-19 have been frequently used in adults, whereas there are little data regarding the safety or efficacy of monoclonal antibody treatments in pediatric patients affected by COVID-19. We report our experience in the administration of mAb as a treatment for SARS-CoV-2 infection in children aged from 24 days to 18 years old

Where May Ultrafast Rotating Neuton Stars Be Hidden?

Disclaimer/Complaints regulations If you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: https://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. ABSTRACT The existence of ultrafast rotating neutron stars (spin period ms) is expected on the basis of current P Շ 1 models for the secular evolution of interacting binaries, although they have not been detected yet. Their formation depends on the quantity of matter accreted by the neutron star which, in turn, is limited by the mechanism of mass ejection from the binary. An efficient mass ejection can avoid the formation of ultrafast pulsars or their accretion-induced collapse to a black hole. We propose that significant reductions of the mass transfer rate may cause the switch-on of a radio pulsar phase, whose radiation pressure may be capable of ejecting out of the system most of the matter transferred by the companion. This can prevent, for long orbital periods and if a sufficiently fast spin has been reached, any further accretion, even if the original transfer rate is restored, thus limiting the minimum spin period attainable by the neutron star. We show that close systems (orbital periods hr) are the only possible hosts for ultrafast spinning neutron stars. This could explain why ultrafast radio P ∼ 1 orb pulsars have not been detected so far, as the detection of pulsars with very short spin periods in close systems is hampered, in current radio surveys, by strong Doppler modulation and computational limitations

Multidrug-Resistant Proteus mirabilis Bloodstream Infections: Risk Factors and Outcomes

Our aims were to identify (i) risk factors associated with the acquisition of multidrug-resistant (MDR, to 3 or more classes of antimicrobials) Proteus mirabilis isolates responsible for bloodstream infections (BSIs) and (ii) the impact on mortality of such infections. Risk factors for acquiring MDR P. mirabilis BSIs were investigated in a case-case-control study; those associated with mortality were assessed by comparing survivors and nonsurvivors in a cohort study. The population consisted of 99 adult inpatients with P. mirabilis BSIs identified by our laboratory over an 11-year period (1999 to 2009), 36 (33.3%) of which were caused by MDR strains, and the overall 21-day mortality rate was 30.3%. Acquisition of an MDR strain was independently associated with admission from a long-term care facility (odds ratio [OR], 9.78; 95% confidence interval [CI], 1.94 to 49.16), previous therapy with fluoroquinolones (OR, 5.52; 95% CI, 1.30 to 23.43) or oxyimino-cephalosporins (OR, 4.72; 95% CI, 1.31 to 16.99), urinary catheterization (OR, 3.89; 95% CI, 1.50 to 10.09), and previous hospitalization (OR, 2.68; 95% CI, 10.4 to 6.89). Patients with MDR P. mirabilis BSIs received inadequate initial antimicrobial therapy (IIAT, i.e., treatment with drugs to which the isolate displayed in vitro resistance) more frequently than those with non-MDR infections; they also had increased mortality and (for survivors) longer post-BSI-onset hospital stays. In multivariate regression analysis, 21-day mortality was associated with septic shock at BSI onset (OR, 12.97; 95% CI, 32.2 to 52.23), P. mirabilis isolates that were MDR (OR, 6.62; 95% CI, 16.4 to 26.68), and IIAT (OR, 9.85; 95% CI, 26.7 to 36.25), the only modifiable risk factor of the 3. These findings can potentially improve clinicians' ability to identify P. mirabilis BSIs likely to be MDR, thereby reducing the risk of IIAT-a major risk factor for mortality in these cases-and facilitating the prompt implementation of appropriate infection control measures

Does the CHA2DS2-VASc score reliably predict atrial arrhythmias? Analysis of a nationwide database of remote monitoring data transmitted daily from cardiac implantable electronic devices

Background CHA2DS2-VASc is a validated score for predicting stroke in patients with atrial fibrillation (AF). Objective The purpose of this study was to assess whether the CHA2DS2-VASc score can predict new-onset AF in a cohort of patients with a cardiac implantable electronic device (CIED) followed with remote monitoring. Methods Using the database of the Home Monitoring Expert Alliance project, we selected 2410 patients with no documented AF who had received a CIED with diagnostics on atrial high rate episodes (AHREs). The primary endpoint was time to first day with cumulative AHRE burden ≥15 minutes, 5 hours, 24 hours, and ≥7 consecutive days. Results During a median duration of 24.1(11.5–42.9) months, the incidence of AHRE increased with increasing CHA2DS2-VASc. At 6 years, occurrence of ≥15-minute AHRE was 80.2% (CHA2DS2-VASc ≤1) vs 93.7% (CHA2DS2-VASc ≥5), whereas ≥5-hour AHRE incidence was 68.4% (CHA2DS2-VASc ≤1) vs 92.5% (CHA2DS2-VASc ≥5). Occurrence of ≥24-hour and ≥7-day AHREs also increased with increasing CHA2DS2-VASc: 9.1% and 3.9% (CHA2DS2-VASc ≤1) vs 40.4% and 28.7% (CHA2DS2-VASc ≥5), respectively. Adjusted hazard ratio for unitary CHA2DS2-VASc increase ranged from 1.09 (confidence interval 1.04–1.14; P <.001) with AHRE burden ≥15 minutes to 1.26 (confidence interval 1.11–1.42; P <.001) with AHRE burden ≥7 days. At receiver operating curve analysis, CHA2DS2-VASc ≥2 was estimated to predict persistent forms of AHREs with 95.8% sensitivity but 11.7% specificity at 3 years. CHA2DS2-VASc ≥5 had 77.0% specificity but 34.6% sensitivity. Conclusion In a CIED population with no previous diagnosis of clinical AF, AHRE incidence increased with increasing CHA2DS2-VASc score. The association was stronger with longer AHREs, but the accuracy of CHA2DS2-VASc as AHRE predictor was moderate

Swings between rotation and accretion power in a binary millisecond pulsar

It is thought that neutron stars in low-mass binary systems can accrete matter and angular momentum from the companion star and be spun-up to millisecond rotational periods. During the accretion stage, the system is called a low-mass X-ray binary, and bright X-ray emission is observed. When the rate of mass transfer decreases in the later evolutionary stages, these binaries host a radio millisecond pulsar whose emission is powered by the neutron star's rotating magnetic field. This evolutionary model is supported by the detection of millisecond X-ray pulsations from several accreting neutron stars and also by the evidence for a past accretion disc in a rotation-powered millisecond pulsar. It has been proposed that a rotation-powered pulsar may temporarily switch on during periods of low mass inflow in some such systems. Only indirect evidence for this transition has hitherto been observed. Here we report observations of accretion-powered, millisecond X-ray pulsations from a neutron star previously seen as a rotation-powered radio pulsar. Within a few days after a month-long X-ray outburst, radio pulses were again detected. This not only shows the evolutionary link between accretion and rotation-powered millisecond pulsars, but also that some systems can swing between the two states on very short timescales