Likelihood-based approach to discriminate mixtures of network models that vary in time.

Discriminating between competing explanatory models as to which is more likely responsible for the growth of a network is a problem of fundamental importance for network science. The rules governing this growth are attributed to mechanisms such as preferential attachment and triangle closure, with a wealth of explanatory models based on these. These models are deliberately simple, commonly with the network growing according to a constant mechanism for its lifetime, to allow for analytical results. We use a likelihood-based framework on artificial data where the network model changes at a known point in time and demonstrate that we can recover the change point from analysis of the network. We then use real datasets and demonstrate how our framework can show the changing importance of network growth mechanisms over time

Using a Bayesian approach to reconstruct graph statistics after edge sampling

Often, due to prohibitively large size or to limits to data collecting APIs, it is not possible to work with a complete network dataset and sampling is required. A type of sampling which is consistent with Twitter API restrictions is uniform edge sampling. In this paper, we propose a methodology for the recovery of two fundamental network properties from an edge-sampled network: the degree distribution and the triangle count (we estimate the totals for the network and the counts associated with each edge). We use a Bayesian approach and show a range of methods for constructing a prior which does not require assumptions about the original network. Our approach is tested on two synthetic and three real datasets with diverse sizes, degree distributions, degree-degree correlations and triangle count distributions

Simplification of networks by conserving path diversity and minimisation of the search information.

Alternative paths in a network play an important role in its functionality as they can maintain the information flow under node/link failures. In this paper we explore the navigation of a network taking into account the alternative paths and in particular how can we describe this navigation in a concise way. Our approach is to simplify the network by aggregating into groups the nodes that do not contribute to alternative paths. We refer to these groups as super-nodes, and describe the post-aggregation network with super-nodes as the skeleton network. We present a method to describe with the least amount of information the paths in the super-nodes and skeleton network. Applying our method to several real networks we observed that there is scaling behaviour between the information required to describe all the paths in a network and the minimal information to describe the paths of its skeleton. We show how from this scaling we can evaluate the information of the paths for large networks with less computational cost

Clinical research:Developing an appropriate career structure

The veterinary profession needs to become more successful in producing the next generation of clinician scientists, say Richard Mellanby and others, who set out a roadmap for future academic postgraduate clinical training

Adrenalectomy alters the sensitivity of the central nervous system melanocortin system

Removal of adrenal steroids by adrenalectomy (ADX) reduces food intake and body weight in rodents and prevents excessive weight gain in many genetic and dietary models of obesity. Thus, glucocorticoids appear to play a key role to promote positive energy balance in normal and pathological conditions. By comparison, central nervous system melanocortin signaling provides critical inhibitory tone to regulate energy balance. The present experiments sought to test whether glucocorticoids influence energy balance by altering the sensitivity to melanocortin receptor ligands. Because melanocortin-producing neurons are hypothesized to be downstream of leptin in a key weight-reducing circuit, we tested rats for their sensitivity to leptin and confirmed reports that the hypophagic response to third ventricular (i3vt) leptin is increased in ADX rats and is normalized by glucocorticoid replacement. Next we tested rats for their sensitivity to the melanocortin agonist melanotan II and found that, as for leptin, ADX enhanced the hypophagic response via a glucocorticoid-dependent mechanism. The central nervous system melanocortin system is unique in that it includes the endogenous melanocortin receptor antagonist, AgRP. The orexigenic effect of i3vt AgRP was absent in ADX rats and restored by glucocorticoid replacement. We conclude that the potent weight-reducing effects of ADX likely involve heightened responsiveness to melanocortin receptor stimulation

Chronic breast abscess due to Mycobacterium fortuitum: a case report

<p>Abstract</p> <p>Introduction</p> <p><it>Mycobacterium fortuitum </it>is a rapidly growing group of nontuberculous mycobacteria more common in patients with genetic or acquired causes of immune deficiency. There have been few published reports of <it>Mycobacterium fortuitum </it>associated with breast infections mainly associated with breast implant and reconstructive surgery.</p> <p>Case presentation</p> <p>We report a case of a 51-year-old Caucasian woman who presented to our one-stop breast clinic with a two-week history of left breast swelling and tenderness. Following triple assessment and subsequent incision and drainage of a breast abscess, the patient was diagnosed with <it>Mycobacterium fortuitum </it>and treated with antibiotic therapy and surgical debridement.</p> <p>Conclusion</p> <p>This is a rare case of a spontaneous breast abscess secondary to <it>Mycobacterium fortuitum </it>infection. Recommended treatment is long-term antibacterial therapy and surgical debridement for extensive infection or when implants are involved.</p

Extragalactic Results from the Infrared Space Observatory

More than a decade ago the IRAS satellite opened the realm of external galaxies for studies in the 10 to 100 micron band and discovered emission from tens of thousands of normal and active galaxies. With the 1995-1998 mission of the Infrared Space Observatory the next major steps in extragalactic infrared astronomy became possible: detailed imaging, spectroscopy and spectro-photometry of many galaxies detected by IRAS, as well as deep surveys in the mid- and far- IR. The spectroscopic data reveal a wealth of detail about the nature of the energy source(s) and about the physical conditions in galaxies. ISO's surveys for the first time explore the infrared emission of distant, high-redshift galaxies. ISO's main theme in extragalactic astronomy is the role of star formation in the activity and evolution of galaxies.Comment: 106 pages, including 17 figures. Ann.Rev.Astron.Astrophys. (in press), a gzip'd pdf file (667kB) is also available at http://www.mpe.mpg.de/www_ir/preprint/annrev2000.pdf.g

The association between antihypertensive treatment and serious adverse events by age and frailty: A cohort study

Background Antihypertensives are effective at reducing the risk of cardiovascular disease, but limited data exist quantifying their association with serious adverse events, particularly in older people with frailty. This study aimed to examine this association using nationally representative electronic health record data. Methods and findings This was a retrospective cohort study utilising linked data from 1,256 general practices across England held within the Clinical Practice Research Datalink between 1998 and 2018. Included patients were aged 40+ years, with a systolic blood pressure reading between 130 and 179 mm Hg, and not previously prescribed antihypertensive treatment. The main exposure was defined as a first prescription of antihypertensive treatment. The primary outcome was hospitalisation or death within 10 years from falls. Secondary outcomes were hypotension, syncope, fractures, acute kidney injury, electrolyte abnormalities, and primary care attendance with gout. The association between treatment and these serious adverse events was examined by Cox regression adjusted for propensity score. This propensity score was generated from a multivariable logistic regression model with patient characteristics, medical history and medication prescriptions as covariates, and new antihypertensive treatment as the outcome. Subgroup analyses were undertaken by age and frailty. Of 3,834,056 patients followed for a median of 7.1 years, 484,187 (12.6%) were prescribed new antihypertensive treatment in the 12 months before the index date (baseline). Antihypertensives were associated with an increased risk of hospitalisation or death from falls (adjusted hazard ratio [aHR] 1.23, 95% confidence interval (CI) 1.21 to 1.26), hypotension (aHR 1.32, 95% CI 1.29 to 1.35), syncope (aHR 1.20, 95% CI 1.17 to 1.22), acute kidney injury (aHR 1.44, 95% CI 1.41 to 1.47), electrolyte abnormalities (aHR 1.45, 95% CI 1.43 to 1.48), and primary care attendance with gout (aHR 1.35, 95% CI 1.32 to 1.37). The absolute risk of serious adverse events with treatment was very low, with 6 fall events per 10,000 patients treated per year. In older patients (80 to 89 years) and those with severe frailty, this absolute risk was increased, with 61 and 84 fall events per 10,000 patients treated per year (respectively). Findings were consistent in sensitivity analyses using different approaches to address confounding and taking into account the competing risk of death. A strength of this analysis is that it provides evidence regarding the association between antihypertensive treatment and serious adverse events, in a population of patients more representative than those enrolled in previous randomised controlled trials. Although treatment effect estimates fell within the 95% CIs of those from such trials, these analyses were observational in nature and so bias from unmeasured confounding cannot be ruled out. Conclusions Antihypertensive treatment was associated with serious adverse events. Overall, the absolute risk of this harm was low, with the exception of older patients and those with moderate to severe frailty, where the risks were similar to the likelihood of benefit from treatment. In these populations, physicians may want to consider alternative approaches to management of blood pressure and refrain from prescribing new treatment

An ISO Long Wavelength Spectrometer detection of CH in NGC 7027 and an HeH + upper limit

We have detected an emission line at 149.18 ± 0.06 Ωm in the ISO Long Wavelength Spectrometer (LWS) grating spectrum of the planetary nebula NGC 7027. This Une coincides in wavelength with both the HeH+ J=1-0 fundamental pure rotational line at 149.14 urn and the CH 2Π3/2 (F2) J=3/2-2Πl/2 (F2) 7= 1/2 fundamental pure rotational lines at 149.09 and 149.39 μm. Another feature of similar strength at 180.7 urn is well-fitted by the CH doublet 2Π1/2 (F1) J=5/2-3/2 at 180.48 and 180.93 μm. We therefore attribute both the 149.18- and 180.7-um lines to CH, the first evidence of this molecule in NGC 7027 and the first detection anywhere of the far-infrared lines of CH in emission. We estimate a CH/CO abundance ratio of ∼ 0.06 and a CH/CH+ ratio of ∼0.2, the latter being more than an order of magnitude lower than predicted for photodissociation regions. The contribution from the HeH+ J=1−0 line to the 149.18-μm feature is at least a factor of three lower than the predictions of Cecchi-Pestellini & Dalgarno (1993)

Predicting the risk of acute kidney injury in primary care: derivation and validation of STRATIFY-AKI

Background: Antihypertensives reduce the risk of cardiovascular disease but are also associated with harms including acute kidney injury (AKI). Few data exist to guide clinical decision making regarding these risks. Aim: To develop a prediction model estimating the risk of AKI in people potentially indicated for antihypertensive treatment. Design and setting: Observational cohort study using routine primary care data from the Clinical Practice Research Datalink (CPRD) in England. Method: People aged ≥40 years, with at least one blood pressure measurement between 130 mmHg and 179 mmHg were included. Outcomes were admission to hospital or death with AKI within 1, 5, and 10 years. The model was derived with data from CPRD GOLD (n = 1 772 618), using a Fine–Gray competing risks approach, with subsequent recalibration using pseudo-values. External validation used data from CPRD Aurum (n = 3 805 322). Results: The mean age of participants was 59.4 years and 52% were female. The final model consisted of 27 predictors and showed good discrimination at 1, 5, and 10 years (C-statistic for 10-year risk 0.821, 95% confidence interval [CI] = 0.818 to 0.823). There was some overprediction at the highest predicted probabilities (ratio of observed to expected event probability for 10-year risk 0.633, 95% CI = 0.621 to 0.645), affecting patients with the highest risk. Most patients (>95%) had a low 1- to 5-year risk of AKI, and at 10 years only 0.1% of the population had a high AKI and low CVD risk. Conclusion: This clinical prediction model enables GPs to accurately identify patients at high risk of AKI, which will aid treatment decisions. As the vast majority of patients were at low risk, such a model may provide useful reassurance that most antihypertensive treatment is safe and appropriate while flagging the few for whom this is not the case