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Effect of topological defects on the elasticity of near-ideal polymer networks
No full textIn recent years, new types of polymer gels have emerged, which have a well-controlled network structure and few topological defects. These so-called near-ideal polymer networks constitute a good model system to revisit the long-standing problem of structure–property relationships in polymer networks, as well as a promising platform for the development of polymer gels with outstanding mechanical properties. In this study, we investigate the relative contributions of network defects (dangling chains and second-order loops) on the stress–stretch response of near-ideal polymer networks using a computational discrete network model. We identify the average chain prestretch as a key parameter to capture the effect of network topology on the elastic modulus and maximum extensibility. Proper account of the chain prestretch further leads to scaling relations for the elastic properties in terms of topology parameters that differ from classical estimates of rubber elasticity theory. Stress–stretch curves calculated using the discrete network model are also compared to semi-analytical estimates
Dorsal Root Ganglion Stimulation Modulates Cortical Gamma Activity in the Cognitive Dimension of Chronic Pain
No full textA cognitive task, the n-back task, was used to interrogate the cognitive dimension of pain in patients with implanted dorsal root ganglion stimulators (DRGS). Magnetoencephalography (MEG) signals from thirteen patients with implanted DRGS were recorded at rest and while performing the n-back task at three increasing working memory loads with DRGS-OFF and the task repeated with DRGS-ON. MEG recordings were pre-processed, then power spectral analysis and source localization were conducted. DRGS resulted in a significant reduction in reported pain scores (mean 23%, p = 0.001) and gamma oscillatory activity (p = 0.036) during task performance. DRGS-induced pain relief also resulted in a significantly reduced reaction time during high working memory load (p = 0.011). A significant increase in average gamma power was observed during task performance compared to the resting state. However, patients who reported exacerbations of pain demonstrated a significantly elevated gamma power (F(3,80) = 65.011612, p < 0.001, adjusted p-value = 0.01), compared to those who reported pain relief during the task. Our findings demonstrate that gamma oscillatory activity is differentially modulated by cognitive load in the presence of pain, and this activity is predominantly localized to the prefrontal and anterior cingulate cortices in a chronic pain cohort
Heterozygous ABCG5 gene deficiency and risk of coronary artery disease
No full textBackground:
Familial sitosterolemia is a rare Mendelian disorder characterized by hyperabsorption and decreased biliary excretion of dietary sterols. Affected individuals typically have complete genetic deficiency—homozygous loss-of-function (LoF) variants—in the ABCG5 or ABCG8 genes and have substantially elevated plasma sitosterol and LDL (low-density lipoprotein) cholesterol (LDL-C) levels. The impact of partial genetic deficiency of ABCG5 or ABCG8—as occurs in heterozygous carriers of LoF variants—on LDL-C and risk of coronary artery disease (CAD) has remained uncertain.
Methods:
We first recruited 9 sitosterolemia families, identified causative LoF variants in ABCG5 or ABCG8, and evaluated the associations of these ABCG5 or ABCG8 LoF variants with plasma phytosterols and lipid levels. We next assessed for LoF variants in ABCG5 or ABCG8 in CAD cases (n=29 321) versus controls (n=357 326). We tested the association of rare LoF variants in ABCG5 or ABCG8 with blood lipids and risk for CAD. Rare LoF variants were defined as protein-truncating variants with minor allele frequency <0.1% in ABCG5 or ABCG8.
Results:
In sitosterolemia families, 7 pedigrees harbored causative LoF variants in ABCG5 and 2 pedigrees in ABCG8. Homozygous LoF variants in either ABCG5 or ABCG8 led to marked elevations in sitosterol and LDL-C. Of those sitosterolemia families, heterozygous carriers of ABCG5 LoF variants exhibited increased sitosterol and LDL-C levels compared with noncarriers. Within large-scale CAD case-control cohorts, prevalence of rare LoF variants in ABCG5 and in ABCG8 was ≈0.1% each. ABCG5 heterozygous LoF variant carriers had significantly elevated LDL-C levels (25 mg/dL [95% CI, 14–35]; P=1.1×10−6) and were at 2-fold increased risk of CAD (odds ratio, 2.06 [95% CI, 1.27–3.35]; P=0.004). By contrast, ABCG8 heterozygous LoF carrier status was not associated with increased LDL-C or risk of CAD.
Conclusions:
Although familial sitosterolemia is traditionally considered as a recessive disorder, we observed that heterozygous carriers of an LoF variant in ABCG5 had significantly increased sitosterol and LDL-C levels and a 2-fold increase in risk of CAD
Email consultations between patients and doctors in primary care: content analysis
No full textBackground: Increasingly, consultations in health care settings are conducted remotely using a range of communication technologies. Email allows for 2-way text-based communication, occurring asynchronously. Studies have explored the content and nature of email consultations to understand the use, structure, and function of email consultations. Most previous content analyses of email consultations in primary care settings have been conducted in North America, and these have shown that concerns and assumptions about how email consultations work have not been realized. There has not been a UK-based content analysis of email consultations.
Objective: This study aims to explore and delineate the content of consultations conducted via email in English general practice by conducting a content analysis of email consultations between general practitioners (GPs) and patients.
Methods: We conducted a content analysis of anonymized email consultations between GPs and patients in 2 general practices in the United Kingdom. We examined the descriptive elements of the correspondence to ascertain when the emails were sent, the number of emails in an email consultation, and the nature of the content. We used a normative approach to analyze the content of the email consultations to explore the use and function of email consultation.
Results: We obtained 100 email consultations from 85 patients, which totaled 262 individual emails. Most email users were older than 40 years, and over half of the users were male. The email consultations were mostly short and completed in a few days. Emails were mostly sent and received during the day. The emails were mostly clinical in content rather than administrative and covered a wide range of clinical presentations. There were 3 key themes to the use and function of the email consultations: the role of the GP and email consultation, the transactional nature of an email consultation, and the operationalization of an email consultation.
Conclusions: Most cases where emails are used to have a consultation with a patient in general practice have a shorter consultation, are clinical in nature, and are resolved quickly. GPs approach email consultations using key elements similar to that of the face-to-face consultation; however, using email consultations has the potential to alter the role of the GP, leading them to engage in more administrative tasks than usual. Email consultations were not a replacement for face-to-face consultations
Trace metals dramatically boost oxygen electrocatalysis of N-doped coal-derived carbon for zinc–air batteries
No full textThe commercialization of metal–air batteries requires efficient, low-cost, and stable bifunctional electrocatalysts for reversible electrocatalysis of the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER). The modification of natural coal by heteroatoms such as N and S, or metal oxide species, has been demonstrated to form very promising electrocatalysts for the ORR and OER. However, it remains elusive and underexplored as to how the impurity elements in coal may impact the electrocatalytic properties of coal-derived catalysts. Herein, we explore the influence of the presence of various trace metals that are notable impurities in coal, including Al, Si, Ca, K, Fe, Mg, Co, Mn, Ni, and Cu, on the electrochemical performance of the prepared catalysts. The constructed Zn–air batteries are further shown to be able to power green LED lights for more than 80 h. The charge–discharge polarization curves exhibited excellent and durable rechargeability over 500 (ca. 84 h) continuous cycles. The promotional effect of the trace elements is believed to accrue from a combination of electronic structure modification of the active sites, enhancement of the active site density, and formation of a conductive 3-dimensional hierarchical network of carbon nanotubes
Transport of high-energy charged particles through spatially-intermittent turbulent magnetic fields
No full textIdentifying the sources of the highest energy cosmic rays requires understanding how they are deflected by the stochastic, spatially intermittent intergalactic magnetic field. Here we report measurements of energetic charged-particle propagation through a laser-produced magnetized plasma with
these properties. We characterize the diffusive transport of the particles experimentally. The results
show that the transport is diffusive and that, for the regime of interest for the highest-energy cosmic
rays, the diffusion coefficient is unaffected by the spatial intermittency of the magnetic field
Class and classification: the London Word Blind Centre for Dyslexic children, 1962–1972
No full textThe Word Blind Centre for Dyslexic Children opened in London in 1963. It was not only the first clinic established in Britain specifically to cater for children diagnosed with dyslexia. It was also intended to provide compelling evidence that a condition called dyslexia actually existed. The results of this work were published in Sandhaya Naidoo’s path-breaking study, Specific Dyslexia, which did exactly what its promoters had hoped it would, drawing on in-depth studies of 196 children to argue that dyslexia was indeed a distinct ‘constitutional disorder’. Using the archives produced by Naidoo and other sources, my article offers the first-ever account of this pioneering enterprise, exploring the reasons the Centre was set up, the way it worked, and the consequences of its work. In particular, it focuses on the rationale for Naidoo’s report, which only dealt with the experiences of middle-class boys. This choice is highly revealing, illuminating attitudes to reading, to class and gender, and to the competition for authority amongst the professionals who sought to explore all these issues. An intriguing case study in its own right, this also sets the scene for many of the themes that follow in this Special Issue
Cosmopolitan patriotism as civic ideals
No full textRecent theoretical debates have questioned the compatibility of patriotism with global political responsibilities, as identified by cosmopolitan theory. In response, several authors claim that a cosmopolitan patriotism is both possible and desirable. In this article, we propose two desiderata for cosmopolitan patriotism as a civic ideal, which existing accounts fail to meet. First, arguments for cosmopolitan patriotism should provide an account of collective identification, supporting the relation between the actions of one's country and one's appropriate reactive attitudes. Second, such a theory should be able to explain the patriot's commitment to critical engagement with her country's actions. We then offer a critical appraisal of two accounts linking patriotism with global responsibility—Permissible Partialism and Globally Responsible Nationalism—‐and demonstrate how they fall short. Finally, we propose an account of civic republican patriotism, which better explains how cosmopolitanism and patriotism can be brought together
The Big-O problem for labelled Markov chains and weighted automata
No full textGiven two weighted automata, we consider the problem of whether one is big-O of the other, i.e., if the weight of every finite word in the first is not greater than some constant multiple of the weight in the second. We show that the problem is undecidable, even for the instantiation of weighted automata as labelled Markov chains. Moreover, even when it is known that one weighted automaton is big-O of another, the problem of finding or approximating the associated constant is also undecidable. Our positive results show that the big-O problem is polynomial-time solvable for unambiguous automata, coNP-complete for unlabelled weighted automata (i.e., when the alphabet is a single character) and decidable, subject to Schanuel’s conjecture, when the language is bounded (i.e., a subset of w_1^* … w_m^* for some finite words w_1,… ,w_m). On labelled Markov chains, the problem can be restated as a ratio total variation distance, which, instead of finding the maximum difference between the probabilities of any two events, finds the maximum ratio between the probabilities of any two events. The problem is related to ε-differential privacy, for which the optimal constant of the big-O notation is exactly exp(ε)