ABSTRACT
Fast radio bursts (FRBs) are short-duration radio pulses of cosmological origin. Among the most common sources predicted to explain this phenomenon are bright pulses from a class of ...extremely highly magnetized neutron stars known as magnetars. Motivated by the discovery of an FRB-like pulse from the Galactic magnetar SGR 1935+2154, we searched for similar events in Messier 82 (M82). With a star formation rate 40 times that of the Milky Way, one might expect that the implied rate of events similar to that seen from SGR 1935+2154 from M82 should be 40 times higher than that of the Milky Way. We observed M82 at 1.4 GHz with the 20-m telescope at the Green Bank Observatory for 34.8 d. While we found many candidate events, none had a signal-to-noise ratio greater than 8. We also show that there are insufficient numbers of repeating low-significance events at similar dispersion measures to constitute a statistically significant detection. From these results, we place an upper bound for the rate of radio pulses from M82 to be 30 yr−1 above a fluence limit of 8.5 Jy ms. While this is less than nine times the rate of radio bursts from magnetars in the Milky Way inferred from the previous radio detections of SGR 1935+2154, it is possible that propagation effects from interstellar scattering are currently limiting our ability to detect sources in M82. Further searches of M82 and other nearby galaxies are encouraged to probe this putative FRB population.
•A method for identifying predictable differences in traffic flow profiles is proposed.•Functional Linear Models are used to analyse the timing of flows.•Statistical tests to compare alternative ...model formulations are presented.•An application to real-life data for a two year period is presented.
It is well known that traffic flows in road networks may vary not only within the day but also between days. Existing models including day-to-day variability usually represent all variability as unpredictable fluctuations. In reality, however, some of the differences in flows on a road may be predictable for transport planners with access to historical data. For example, flow profiles may be systematically different on Mondays compared to Fridays due to predictable differences in underlying activity patterns. By identifying days of the week or times of year where flows are predictably different, models can be developed or model inputs can be amended (in the case of day-to-day dynamical models) to test the robustness of proposed policies or to inform the development of policies which vary according to these predictably different day types. Such policies could include time-of-day varying congestion charges that themselves vary by day of the week or season, or targeting public transport provision so that timetables are more responsive to the day of the week and seasonal needs of travellers. A statistical approach is presented for identifying systematic variations in daily traffic flow profiles based on known explanatory factors such as the day of the week and the season. In order to examine day-to-day variability whilst also considering within-day dynamics, the distribution of flows throughout a day are analysed using Functional Linear Models. F-type tests for functional data are then used to compare alternative model specifications for the predictable variability. The output of the method is an average flow profile for each predictably different day type, which could include day of the week or time of year. An application to real-life traffic flow data for a two-year period is provided. The shape of the daily profile was found to be significantly different for each day of the week, including differences in the timing and width of peak flows and also the relationship between peak and inter-peak flows. Seasonal differences in flow profiles were also identified for each day of the week.
In the UK, colorectal cancer (CRC) is the third most common malignancy (behind lung and breast cancer) with 37,514 cases registered in 2006: around two-thirds (23,384) in the colon and one-third ...(14,130) in the rectum. Treatment of cancers of the colon can vary considerably, but surgical resection is the mainstay of treatment for curative intent. Following surgical resection, there is a comprehensive assessment of the tumour, it's invasion characteristics and spread (tumour staging). A number of imaging modalities are used in the pre-operative staging of CRCs including; computerised tomography (CT), magnetic resonance imaging, ultrasound imaging and positron emission tomography (PET). This report examines the role of CT in combination with PET scanning (PET/CT 'hybrid' scan). The research objectives are: to evaluate the diagnostic accuracy and therapeutic impact of fluorine-18-deoxyglucose (FDG) PET/CT for the pre-operative staging of primary, recurrent and metastatic cancer using systematic review methods; undertake probabilistic decision-analytic modelling (using Monte Carlo simulation); and conduct a value of information analysis to help inform whether or not there is potential worth in undertaking further research.
For each aspect of the research - the systematic review, the handsearch study and the economic evaluation - a database was assembled from a comprehensive search for published and unpublished studies, which included database searches, reference lists search and contact with experts. In the systematic review prospective and retrospective patient series (diagnostic cohort) and randomised controlled trials (RCTs) were eligible for inclusion. Both consecutive series and series that are not explicitly reported as consecutive were included.
Two reviewers extracted all data and applied the criteria independently and resolved disagreements by discussion. Data to populate 2 × 2 contingency tables consisting of the number of true positives, true negatives, false positives and false negatives using the studies' own definitions were extracted, as were data relating to changes in management. Fourteen items from the Quality Assessment of Diagnostic Accuracy Studies checklist were used to assess the methodological quality of the included studies. Patient-level data were used to calculate sensitivity and specificity with confidence intervals (CIs). Data were plotted graphically in forest plots. For the economic evaluation, economic models were designed for each of the disease states: primary, recurrent and metastatic. These were developed and populated based on a variety of information sources (in particular from published data sources) and literature, and in consultation with clinical experts.
The review found 30 studies that met the eligibility criteria. Only two small studies evaluated the use of FDG PET/CT in primary CRC, and there is insufficient evidence to support its routine use at this time. The use of FDG PET/CT for the detection of recurrent disease identified data from five retrospective studies from which a pooled sensitivity of 91% (95% CI 0.87% to 0.95%) and specificity of 91% (95% CI 0.85% to 0.95%) were observed. Pooled accuracy data from patients undergoing staging for suspected metastatic disease showed FDG PET/CT to have a pooled sensitivity of 91% (95% CI 87% to 94%) and a specificity of 76% (95% CI 58% to 88%), but the poor quality of the studies means the validity of the data may be compromised by several biases. The separate handsearch study did not yield any additional unique studies relevant to FDG PET/CT. Models for recurrent disease demonstrated an incremental cost-effectiveness ratio of £ 21,409 per quality-adjusted life-year (QALY) for rectal cancer, £ 6189 per QALY for colon cancer and £ 21,434 per QALY for metastatic disease. The value of handsearching to identify studies of less clearly defined or reported diagnostic tests is still to be investigated.
The systematic review found insufficient evidence to support the routine use of FDG PET/CT in primary CRC and only a small amount of evidence supporting its use in the pre-operative staging of recurrent and metastatic CRC, and, although FDG PET/CT was shown to change patient management, the data are divergent and the quality of research is generally poor. The handsearch to identify studies of less clearly defined or reported diagnostic tests did not find additional studies. The primary limitations in the economic evaluations were due to uncertainty and lack of available evidence from the systematic reviews for key parameters in each of the five models. In order to address this, a conservative approach was adopted in choosing DTA estimates for the model parameters. Probabilistic analyses were undertaken for each of the models, incorporating wide levels of uncertainty particularly for the DTA estimates. None of the economic models reported cost-savings, but the approach adopted was conservative in order to determine more reliable results given the lack of current information. The economic evaluations conclude that FDG PET/CT as an add-on imaging device is cost-effective in the pre-operative staging of recurrent colon, recurrent rectal and metastatic disease but not in primary colon or rectal cancers. There would be value in undertaking an RCT with a concurrent economic evaluation to evaluate the therapeutic impact and cost-effectiveness of FDG PET/CT compared with conventional imaging (without PET) for the pre-operative staging of recurrent and metastatic CRC.
We have searched three Parkes multibeam 1.4 GHz surveys for the presence of fast radio bursts (FRBs) out to a dispersion measure (DM) of 5000 pc cm−3. These surveys originally targeted the Magellanic ...Clouds (in two cases) and unidentified gamma-ray sources at mid-Galactic latitudes (in the third case) for new radio pulsars. In previous processing, none of these surveys were searched to such a high DM limit. The surveys had a combined total of 719 h of Parkes multibeam on-sky time. One known FRB, 010724, was present in our data and was detected in our analysis but no new FRBs were found. After adding in the on-sky Parkes time from these three surveys to the on-sky time (7512 h) from the five Parkes surveys analysed by Rane et al., all of which have now been searched to high DM limits, we improve the constraint on the all-sky rate of FRBs above a fluence level of 3.8 Jy ms at 1.4 GHz to
$R = 3.3^{+3.7}_{-2.2} \times 10^{3}$
events per day per sky (at the 99 per cent confidence level). Future Parkes surveys that accumulate additional multibeam on-sky time (such as the ongoing high-resolution Parkes survey of the Large Magellanic Cloud) can be combined with these results to further constrain the all-sky FRB rate.
We present timing observations of 4-ms pulsars discovered in the Parkes 20-cm multibeam pulsar survey of the Galactic plane. PSRs J1552−4937 and J1843−1448 are isolated objects with spin periods of ...6.28 and 5.47 ms, respectively. PSR J1727−2946 is in a 40-d binary orbit and has a spin period of 27 ms. The 4.43-ms pulsar J1813−2621 is in a circular 8.16-d binary orbit around a low-mass companion star with a minimum companion mass of 0.2 M⊙. Combining these results with detections from five other Parkes multibeam surveys, gives a well-defined sample of 56 pulsars with spin periods below 20 ms. We develop a likelihood analysis to constrain the functional form which best describes the underlying distribution of spin periods for millisecond pulsars. The best results were obtained with a lognormal distribution. A gamma distribution is less favoured, but still compatible with the observations. Uniform, power-law and Gaussian distributions are found to be inconsistent with the data. Galactic millisecond pulsars being found by current surveys appear to be in agreement with a lognormal distribution which allows for the existence of pulsars with periods below 1.5 ms.
The theoretical potential for carbon forests to off-set greenhouse gas emissions may be high but the achievable rate is influenced by a range of economic and social factors. Economic returns (net ...present value, NPV) were calculated spatially across the cleared land area in Australia for ‘environmental carbon plantings’. A total of 105 scenarios were run by varying discount rate, carbon price, rate of carbon sequestration and costs for plantation establishment licenses for water interception. The area for which NPV was positive ranged from zero ha for tightly constrained scenarios to almost the whole of the cleared land (104 M ha) for lower discount rate and highest carbon price. For the most plausible assumptions for cost of establishment and commercial discount rate, no areas were identified as profitable until a carbon price of AUD$40 t CO
2
−1
was reached. The many practical constraints to plantation establishment mean that it will likely take decades to have significant impact on emission reductions. Every 1 M ha of carbon forests established would offset about 1.4 % of Australia’s year 2000 emissions (or 7.4 Mt CO
2
year
−1
) when an average rate of sequestration per ha was reached. All studies that predict large areas of potentially profitable land for carbon forestry need to be tempered by the realities that constrain land use change. In Australia and globally, carbon plantings can be a useful activity to help mitigate emissions and restore landscapes but it should be viewed as a long-term project in which co-benefits such as biodiversity enhancement can be realised.
We present the discovery of eight new radio pulsars located in the Large Magellanic Cloud (LMC). Five of these pulsars were found from reprocessing the Parkes Multibeam Survey of the Magellanic ...Clouds, while the remaining three were from an ongoing new survey at Parkes with a high-resolution data acquisition system. It is possible that these pulsars were missed in the earlier processing due to radio frequency interference, visual judgment or the large number of candidates that must be analysed. One of these new pulsars has a dispersion measure of 273 pc cm−3, almost twice the highest previously known value, making it possibly the most distant LMC pulsar. In addition, we present the null result of a radio pulse search of an X-ray point source located in SNR J0047.2−7308 in the Small Magellanic Cloud (SMC). Although no millisecond pulsars have been found, these discoveries have increased the known rotation-powered pulsar population in the LMC by more than 50 per cent. Using the current sample of LMC pulsars, we used a Bayesian analysis to constrain the number of potentially observable pulsars in the LMC to within a 95 per cent credible interval of 57 000+70000
−30000. The new survey at Parkes is ∼20 per cent complete, and it is expected to yield at most six millisecond pulsars in the LMC and SMC. Although it is very sensitive to short period pulsars, this new survey provides only a marginal increase in sensitivity to long periods. The limiting luminosity for this survey is 125 mJy kpc2 for the LMC which covers the upper 10 per cent of all known radio pulsars. The luminosity function for normal pulsars in the LMC is consistent with their counterparts in the Galactic disc. The maximum 1400 MHz radio luminosity for LMC pulsars is ∼1000 mJy kpc2.
Abstract
We present new discoveries and results from long-term timing of 72 pulsars discovered in the Pulsar Arecibo
L
-band Feed Array (PALFA) survey, including precise determination of astrometric ...and spin parameters, and flux density and scatter broadening measurements at 1.4 GHz. Notable discoveries include two young pulsars (characteristic ages ∼30 kyr) with no apparent supernova remnant associations, three mode-changing, 12 nulling and two intermittent pulsars. We detected eight glitches in five pulsars. Among them is PSR J1939+2609, an apparently old pulsar (characteristic age ∼1 Gy), and PSR J1954+2529, which likely belongs to a newly emerging class of binary pulsars. The latter is the only pulsar among the 72 that is clearly not isolated: a nonrecycled neutron star with a 931 ms spin period in an eccentric (
e
= 0.114) wide (
P
b
= 82.7 days) orbit with a companion of undetermined nature having a minimum mass of ∼0.6
M
⊙
. Since operations at Arecibo ceased in 2020 August, we give a final tally of PALFA sky coverage, and compare its 207 pulsar discoveries to the known population. On average, they are 50% more distant than other Galactic plane radio pulsars; PALFA millisecond pulsars (MSPs) have twice the dispersion measure per unit spin period than the known population of MSP in the plane. The four intermittent pulsars discovered by PALFA more than double the population of such objects, which should help to improve our understanding of pulsar magnetosphere physics. The statistics for these, rotating radio transients, and nulling pulsars suggest that there are many more of these objects in the Galaxy than was previously thought.
What it's really like to be a parent in the world of
higher education, and how academia can make this hard climb a
little less steep
Academia has a big problem. For many parents-especially
...mothers-the idea of "work-life balance" is a work-life myth.
Parents and caregivers work harder than ever to grow and thrive in
their careers while juggling the additional responsibilities that
accompany parenthood. Sudden disruptions and daily constraints such
as breastfeeding, sick days that keep children home from school,
and the sleep deprivation that plagues the early years of parenting
threaten to derail careers. Some experience bias and harassment
related to pregnancy or parental leave. The result is an academic
Chutes and Ladders, where career advancement is nearly impossible
for parents who lack access to formal or informal support
systems.
In The PhD Parenthood Trap , Kerry F. Crawford and Leah
C. Windsor reveal the realities of raising kids, on or off the
tenure track, and suggest reforms to help support parents
throughout their careers. Insights from their original survey data
and poignant vignettes from scholars across disciplines make it
clear that universities lack understanding, uniform policies, and
flexibility for family formation, hurting the career development of
parent-scholars. Each chapter includes recommendations for best
practices and policy changes that will help make academia an
exemplar of progressive family-leave policies. Topics covered
include pregnancy, adoption, miscarriage and infant loss,
postpartum depression, family leave, breastfeeding, daily parenting
challenges, the tenure clock, and more. The book concludes with
advice to new or soon-to-be parents to help them better navigate
parenthood in academia.
The PhD Parenthood Trap provides scholars, academic
mentors, and university administrators with empirical evidence and
steps to break down personal and structural barriers between
parenthood and scholarly careers.
For many parents, the idea of "work-life balance" is a work-life
myth. In The PhD Parenthood Trap , Kerry F. Crawford and
Leah C. Windsor use insights from original survey data and
vignettes from scholars to reveal the realities of raising kids in
academia and suggest reforms to help support parents throughout
their careers.
Background
Fungal infections of the feet normally occur in the outermost layer of the skin (epidermis). The skin between the toes is a frequent site of infection which can cause pain and itchiness. ...Fungal infections of the nail (onychomycosis) can affect the entire nail plate.
Objectives
To assess the effects of topical treatments in successfully treating (rate of treatment failure) fungal infections of the skin of the feet and toenails and in preventing recurrence.
Search methods
We searched the Cochrane Skin Group Specialised Register (January 2005), the Cochrane Central Register of Controlled Trials (The Cochrane Library Issue 1, 2005), MEDLINE and EMBASE (from inception to January 2005). We screened the Science Citation Index, BIOSIS, CAB ‐ Health and Healthstar, CINAHL DARE, NHS Economic Evaluation Database and EconLit (March 2005). Bibliographies were searched.
Selection criteria
Randomised controlled trials (RCTs) using participants who had mycologically diagnosed fungal infections of the skin and nails of the foot.
Data collection and analysis
Two authors independently summarised the included trials and appraised their quality of reporting using a structured data extraction tool.
Main results
Of the 144 identified papers, 67 trials met the inclusion criteria. Placebo‐controlled trials yielded the following pooled risk ratios (RR) of treatment failure for skin infections: allylamines RR 0.33 (95% CI 0.24 to 0.44); azoles RR 0.30 (95% CI 0.20 to 0.45); ciclopiroxolamine RR 0.27 (95% CI 0.11 to 0.66); tolnaftate RR 0.19 (95% CI 0.08 to 0.44); butenafine RR 0.33 (95% CI 0.24 to 0.45); undecanoates RR 0.29 (95% CI 0.12 to 0.70). Meta‐analysis of 11 trials comparing allylamines and azoles showed a risk ratio of treatment failure RR 0.63 (95% CI 0.42 to 0.94) in favour of allylamines. Evidence for the management of topical treatments for infections of the toenails is sparser. There is some evidence that ciclopiroxolamine and butenafine are both effective but they both need to be applied daily for prolonged periods (at least one year). The six trials of nail infections provided evidence that topical ciclopiroxolamine has poor cure rates and that amorolfine might be substantially more effective but more research is required.
Authors' conclusions
Placebo‐controlled trials of allylamines and azoles for athlete's foot consistently produce much higher percentages of cure than placebo. Allylamines cure slightly more infections than azoles and are now available OTC. Further research into the effectiveness of antifungal agents for nail infections is required.
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