ABSTRACT
We report on a timing programme of 74 young pulsars that have been observed by the Parkes 64-m radio telescope over the past decade. Using modern Bayesian timing techniques, we have measured ...the properties of 124 glitches in 52 of these pulsars, of which 74 are new. We demonstrate that the glitch sample is complete to fractional increases in spin frequency greater than $\Delta \nu ^{90{{\ \rm per\ cent}}}_{\mathrm{ g}}/\nu \approx 8.1 \times 10^{-9}$ . We measure values of the braking index, n, in 33 pulsars. In most of these pulsars, their rotational evolution is dominated by episodes of spin-down with n > 10, punctuated by step changes in the spin-down rate at the time of a large glitch. The step changes are such that, averaged over the glitches, the long-term n is small. We find a near one-to-one relationship between the interglitch value of n and the change in spin-down of the previous glitch divided by the interglitch time interval. We discuss the results in the context of a range of physical models.
Pulsar polarization: a partial-coherence model Oswald, L S; Karastergiou, A; Johnston, S
Monthly notices of the Royal Astronomical Society,
08/2023, Letnik:
525, Številka:
1
Journal Article
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ABSTRACT
The population of radio pulsars is observed to demonstrate certain polarization properties not explained by the conventional picture of pulsar polarization, namely frequency evolution of ...polarization, deviations of the linear polarization angle from a curve of geometric origins, and the presence of features in the circular polarization. We present the partial-coherence model as a way to explain the co-occurrence of these features and to provide an origin for circular polarization in radio pulsar profiles. We describe the mathematics of the model and demonstrate how it can explain these observed features, both on a population level and for the idiosyncrasies of individual pulsars. The partial coherence model can account for complex polarization behaviour, enabling improved access to information about pulsar geometries. We discuss the scientific implications of this for our understanding of pulsar radio emission and propagation.
All-optical approaches to particle acceleration are currently attracting a significant research effort internationally. Although characterized by exceptional transverse and longitudinal emittance, ...laser-driven ion beams currently have limitations in terms of peak ion energy, bandwidth of the energy spectrum and beam divergence. Here we introduce the concept of a versatile, miniature linear accelerating module, which, by employing laser-excited electromagnetic pulses directed along a helical path surrounding the laser-accelerated ion beams, addresses these shortcomings simultaneously. In a proof-of-principle experiment on a university-scale system, we demonstrate post-acceleration of laser-driven protons from a flat foil at a rate of 0.5 GeV m(-1), already beyond what can be sustained by conventional accelerator technologies, with dynamic beam collimation and energy selection. These results open up new opportunities for the development of extremely compact and cost-effective ion accelerators for both established and innovative applications.
ABSTRACT
We describe the ongoing Relativistic Binary programme (RelBin), a part of the MeerTime large survey project with the MeerKAT radio telescope. RelBin is primarily focused on observations of ...relativistic effects in binary pulsars to enable measurements of neutron star masses and tests of theories of gravity. We selected 25 pulsars as an initial high priority list of targets based on their characteristics and observational history with other telescopes. In this paper, we provide an outline of the programme, and present polarization calibrated pulse profiles for all selected pulsars as a reference catalogue along with updated dispersion measures. We report Faraday rotation measures for 24 pulsars, twelve of which have been measured for the first time. More than a third of our selected pulsars show a flat position angle swing confirming earlier observations. We demonstrate the ability of the Rotating Vector Model, fitted here to seven binary pulsars, including the Double Pulsar (PSR J0737–3039A), to obtain information about the orbital inclination angle. We present a high time resolution light curve of the eclipse of PSR J0737–3039A by the companion’s magnetosphere, a high-phase-resolution position angle swing for PSR J1141–6545, an improved detection of the Shapiro delay of PSR J1811–2405, and pulse scattering measurements for PSRs J1227–6208, J1757–1854, and J1811–1736. Finally, we demonstrate that timing observations with MeerKAT improve on existing data sets by a factor of, typically, 2–3, sometimes by an order of magnitude.
In the primary motor cortex (M1), layer 5 projection neurons signal directly to distant motor structures to drive movement. Despite their pivotal position and acknowledged diversity these neurons are ...traditionally separated into broad commissural and corticofugal types, and until now no attempt has been made at resolving the basis for their diversity. We therefore probed the electrophysiological and morphological properties of retrogradely labeled M1 corticospinal (CSp), corticothalamic (CTh), and commissural projecting corticostriatal (CStr) and corticocortical (CC) neurons. An unsupervised cluster analysis established at least four phenotypes with additional differences between lumbar and cervical projecting CSp neurons. Distinguishing parameters included the action potential (AP) waveform, firing behavior, the hyperpolarisation-activated sag potential, sublayer position, and soma and dendrite size. CTh neurons differed from CSp neurons in showing spike frequency acceleration and a greater sag potential. CStr neurons had the lowest AP amplitude and maximum rise rate of all neurons. Temperature influenced spike train behavior in corticofugal neurons. At 26°C CTh neurons fired bursts of APs more often than CSp neurons, but at 36°C both groups fired regular APs. Our findings provide reliable phenotypic fingerprints to identify distinct M1 projection neuron classes as a tool to understand their unique contributions to motor function.
ABSTRACT
In spite of the rich phenomenology of the polarization properties of radio pulsars, the rotating vector model (RVM) created 50 years ago remains the best method to determine the beam ...geometry of a pulsar. We apply the RVM to a sample of 854 radio pulsars observed with the MeerKAT telescope in order to draw conclusions about the population of pulsars as a whole. The main results are that (i) the geometrical interpretation of the position angle (PA) traverse is valid in the majority of the population, (ii) the pulsars for which the RVM fails tend to have a high fraction of circular polarization compared to linear polarization, (iii) emission heights obtained through both geometrical and relativistic methods show that the majority of pulsars must have emission heights less than 1000 km independent of the spin period, (iv) orthogonal mode jumps are seen in the PA traverse in about one third of the population. All these results are weakly dependent on the pulsar spin-down energy.
ABSTRACT
The major programme for observing young, non-recycled pulsars with the Parkes telescope has transitioned from a narrow-band system to an ultra-wide-band system capable of observing between ...704 and 4032 MHz. We report here on the initial 2 yr of observations with this receiver. Results include dispersion measure (DM) and Faraday rotation measure (RM) variability with time, determined with higher precision than hitherto, flux density measurements and the discovery of several nulling and mode changing pulsars. PSR J1703−4851 is shown to be one of a small subclass of pulsars that has a weak and a strong mode which alternate rapidly in time. PSR J1114−6100 has the fourth highest |RM| of any known pulsar despite its location far from the Galactic Centre. PSR J1825−1446 shows variations in both DM and RM likely due to its motion behind a foreground supernova remnant.
Rapid implementation of telehealth for cancer care during COVID-19 required innovative and adaptive solutions among oncology health care providers and professionals (HPPs).
The aim of this ...qualitative study was to explore oncology HPPs' experiences with telehealth implementation during the COVID-19 pandemic.
This study was conducted at Moffitt Cancer Center (Moffitt), an NCI (National Cancer Institute)-Designated Comprehensive Cancer Center. Prior to COVID-19, Moffitt piloted telehealth visits on a limited basis. After COVID-19, Moffitt rapidly expanded telehealth visits. Telehealth visits included real-time videoconferencing between HPPs and patients and virtual check-ins (ie, brief communication with an HPP by telephone only). We conducted semistructured interviews with 40 oncology HPPs who implemented telehealth during COVID-19. The interviews were recorded, transcribed verbatim, and analyzed for themes using Dedoose software (version 4.12).
Approximately half of the 40 participants were physicians (n=22, 55%), and one-quarter of the participants were advanced practice providers (n=10, 25%). Other participants included social workers (n=3, 8%), psychologists (n=2, 5%), dieticians (n=2, 5%), and a pharmacist (n=1, 3%). Five key themes were identified: (1) establishing and maintaining patient-HPP relationships, (2) coordinating care with other HPPs and informal caregivers, (3) adapting in-person assessments for telehealth, (4) developing workflows and allocating resources, and (5) future recommendations. Participants described innovative strategies for implementing telehealth, such as coordinating interdisciplinary visits with multiple HPPs and inviting informal caregivers (eg, spouse) to participate in telehealth visits. Health care workers discussed key challenges, such as workflow integration, lack of physical exam and biometric data, and overcoming the digital divide (eg, telehealth accessibility among patients with communication-related disabilities). Participants recommended policy advocacy to support telehealth (eg, medical licensure policies) and monitoring how telehealth affects patient outcomes and health care delivery.
To support telehealth growth, implementation strategies are needed to ensure that HPPs and patients have the tools necessary to effectively engage in telehealth. At the same time, cancer care organizations will need to engage in advocacy to ensure that policies are supportive of oncology telehealth and develop systems to monitor the impact of telehealth on patient outcomes, health care quality, costs, and equity.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Background
Social isolation and connectedness are social determinants of health that have demonstrated effects on cancer‐related outcomes. These constructs have been systematically evaluated among ...pediatric and older adult cancer populations. In this review, the authors evaluated the prevalence, correlates, and psychosocial implications of social isolation and connectedness among young adult (YA) cancer survivors aged 18–39 years.
Methods
Peer‐reviewed articles published in English before June 2021 were identified from database searches and included articles' reference lists according to PRISMA (Preferred Reporting Items for Systematic Reviews and Meta‐Analyses) guidelines. Included articles described studies that assessed social isolation and/or connectedness among YA cancer survivors.
Results
In total, 5094 unique records were identified; 4143 were excluded after title/ screening, and 907 were excluded after full‐text review. Forty‐four articles were included. Few studies used validated measures or directly assessed social isolation or connectedness. Social isolation was similarly prevalent among YAs and older cancer survivors and noncancer populations. Demographic, clinical, and behavioral risk and protective factors for social isolation were identified. Social isolation was related to worse psychological well‐being, whereas social connectedness was often, but not always, related to better psychological well‐being.
Conclusions
This growing literature underscores the relevance of social isolation and connectedness as important health determinants among YA cancer survivors. The identified risk and protective factors can identify YAs who especially may benefit from screening for social isolation. Future studies are needed that directly, reliably, and validly evaluate social isolation and connectedness to inform the development of interventions to decrease isolation and increase connectedness.
This review evaluated the prevalence, correlates, and psychosocial implications of social isolation and connectedness among young adult (YA) cancer survivors. Findings underscored the relevance of social isolation and connectedness as important health determinants among YA cancer survivors, identified risk and protective factors that can help identify YAs who may especially benefit from screening for social isolation, and provided recommendations for future research.
Purpose
This study provides an updated evaluation of the prevalence and severity of acute cancer-related symptoms and quality of life (QOL) concerns among patients treated with emetogenic ...chemotherapy.
Methods
Patients were recruited to a larger, multi-site observational study prior to starting chemotherapy. Participants completed sociodemographic questionnaires and clinical data were abstracted via medical record review. Symptoms and QOL were assessed 5 days after starting moderately or highly emetogenic chemotherapy. Functional Assessment of Cancer Therapy – General assessed QOL concerns. Patient Reported Outcomes version of the Common Terminology Criteria for Adverse Events evaluated symptoms. Symptoms were considered severe when participants responded “severe” or “very severe.”
Results
Participants (
N
= 1174) were on average 58 ± 13 years, mostly female (73%), non-Hispanic (89%), and White (87%). Most participants were diagnosed with breast (38.1%), gynecological (20%), and gastrointestinal (17.1%) cancer. The most common QOL concerns of any severity were fatigue (94%), anhedonia (89%), dissatisfaction with QOL (86%), and sleep disturbance (86%). The most common severe QOL concerns were anhedonia (44%), fatigue (40%), and inability to work (38%). Decreased appetite (74%), pain (71%), and constipation (70%) were the most common symptoms of any severity, as well as most common severe symptoms (13%, 18%, and 18%, respectively).
Conclusion
Herein, updates are provided in regard to QOL concerns and symptoms reported by patients in the days after chemotherapy and demonstrates that concerns and symptoms have shifted in the last decade.
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