Frameworks for logically classifying polynomial-time optimisation problems.

We show that a logical framework, based around a fragment of existential second-order logic formerly proposed by others so as to capture the class of polynomially-bounded P-optimisation problems, cannot hope to do so, under the assumption that P ≠ NP. We do this by exhibiting polynomially-bounded maximisation and minimisation problems that can be expressed in the framework but whose decision versions are NP-complete. We propose an alternative logical framework, based around inflationary fixed-point logic, and show that we can capture the above classes of optimisation problems. We use the inductive depth of an inflationary fixed-point as a means to describe the objective functions of the instances of our optimisation problems

The limits of popularity-based recommendations, and the role of social ties

In this paper we introduce a mathematical model that captures some of the salient features of recommender systems that are based on popularity and that try to exploit social ties among the users. We show that, under very general conditions, the market always converges to a steady state, for which we are able to give an explicit form. Thanks to this we can tell rather precisely how much a market is altered by a recommendation system, and determine the power of users to influence others. Our theoretical results are complemented by experiments with real world social networks showing that social graphs prevent large market distortions in spite of the presence of highly influential users

Recurrent prurigo nodularis related to infected tonsils: a case report

This is an Open Access article distributed under the terms of the Creative Commons Attribution Licens

The Impact of Biliary Injury on the Recurrence of Biliary Cancer and Benign Disease after Liver Transplantation: Risk Factors and Mechanisms

Liver transplantation is known to generate significant inflammation in the entire organ based on the metabolic profile and the tissue’s ability to recover from the ischemia-reperfusion injury (IRI). This cascade contributes to post-transplant complications, affecting both the synthetic liver function (immediate) and the scar development in the biliary tree. The new occurrence of biliary strictures, and the recurrence of malignant and benign liver diseases, such as cholangiocarcinoma (CCA) and primary sclerosing cholangitis (PSC), are direct consequences linked to this inflammation. The accumulation of toxic metabolites, such as succinate, causes undirected electron flows, triggering the releases of reactive oxygen species (ROS) from a severely dysfunctional mitochondrial complex 1. This initiates the inflammatory IRI cascade, with subsequent ischemic biliary stricturing, and the upregulation of pro-tumorigenic signaling. Such inflammation is both local and systemic, promoting an immunocompromised status that can lead to the recurrence of underlying liver disease, both malignant and benign in nature. The traditional treatment for CCA was resection, when possible, followed by cytotoxic chemotherapy. Liver transplant oncology is increasingly recognized as a potentially curative approach for patients with intrahepatic (iCCA) and perihilar (pCCA) cholangiocarcinoma. The link between IRI and disease recurrence is increasingly recognized in transplant oncology for hepatocellular carcinoma. However, smaller numbers have prevented similar analyses for CCA. The mechanistic link may be even more critical in this disease, as IRI causes the most profound damage to the intrahepatic bile ducts. This article reviews the underlying mechanisms associated with biliary inflammation and biliary pathology after liver transplantation. One main focus is on the link between transplant-related IRI-associated inflammation and the recurrence of cholangiocarcinoma and benign liver diseases of the biliary tree. Risk factors and protective strategies are highlighted

I read it on reddit: Exploring the role of online communities in the 2016 US elections news cycle

Reddit has developed into a significant platform for political discussion among Millennials. In this exploratory study, we examine subscription trends on three political sub-forums on Reddit during the 2016 US presidential elections: /The_Donald, /SandersForPresident, and /HillaryClinton. As a theoretical framework, we draw from work on online communities’ group identity and cohesion. Concretely, we investigate how subscription dynamics relate to positive, negative and neutral news events occurring during the election cycle. We classify news events using a sentiment analysis of event-related news headlines. We observe that users who supported Sanders displayed no consolidation of support for Clinton after she won the Democratic Party’s presidential nomination. Secondly, we show that negative news events affected Sanders and Clintons subscription trends negatively, while showing no effect for Donald Trump. This gives empirical credence to Trump’s controversial claim that he could “stand in the middle of 5th Avenue and shoot somebody and not lose any voters”. We offer a number of explanations for the observed phenomena: the nature of the content of the three subreddits, their cultural dynamics, and changing dynamics of partisanship. We posit that the ‘death of expertise’ expresses itself on Reddit as a switch in persuasion tactics from a policy-based to an emotions-based approach, and that group members’ agreement on policy proved a weak marker for online communities’ group identity and cohesion. We also claim that strong partisanship coupled with weak party affiliation among Millennials contributed to the low levels of Democratic support consolidation after Clinton won the nomination

Control of Transdermal Permeation of Hydrocortisone Acetate from Hydrophilic and Lipophilic Formulations

The purpose of this research was the preparation of four formulations containing hydrocortisone acetate (HCA) for topical application, including two aqueous systems (hydrophilic microemulsion and aqueous gel) and two systems with dominant hydrophobicity (hydrophobic microemulsion and ointment). The formulations were tested for the release and permeation of HCA across an animal membrane. The release of HCA was found comparable for the four systems. The two microemulsions promote permeation across an ex-vivo membrane, examined by means of a Franz cell. Hydrophobic microemulsion guarantees the highest solubility (2,370 μg/ml) and flux (133 μg/cm2.h) of the drug, since it contains almost 40% Transcutol, a permeation enhancer. Gel and ointment provide lower solubility and flux, being the values, related to the ointment, the lowest ones (562 μg/ml and 0.4 μg/cm2.h). Experimental results allow the conclusion that gel and ointment can be suitable when it is desirable to minimize absorption of topically applied HCA as to keep the drug restricted to the diseased area and prevent side effects of the systemic presence of HCA

Quantifying Flavin mononucleotide: an internationally validated methodological approach for enhanced decision making in organ transplantation

Background: Increasing donor risk, particularly in liver transplantation, where organs are often marginal, has made dynamic organ preservation techniques and viability assessment essential to safely improve organ quality and increase utilisation. However, existing viability parameters are based on routine clinical assessment in patients with acute liver failure, trauma, or liver resections. These parameters often do not correlate with clinically relevant post-transplant outcomes.Methods: This article presents a detailed protocol for the spectrophotometric quantification of Flavin mononucleotide (FMN), a marker of mitochondrial injury. FMN release from mitochondrial complex I was described many decades ago as the initial sign of ischaemia-reperfusion injury, i.e. when oxygen is reintroduced in ischaemic tissues during organ transplantation or machine perfusion. This study describes the detailed FMN quantification in donor plasma and various fluids obtained during machine perfusion, and discusses confounders, challenges, and the role of individual test components.Findings: FMN quantification was identified as an immediate organ assessment tool, demonstrating a strong correlation with graft survival and other relevant complications after human liver transplantation.Interpretation: The results highlight FMN quantification as a reliable and standardized method for assessing organ viability, offering significant potential for improving organ selection and better utilisation. This method could provide better a predictive value for transplant outcomes compared to existing parameters currently in use

Association between lifestyle factors and headache

Modification of lifestyle habits is a key preventive strategy for many diseases. The role of lifestyle for the onset of headache in general and for specific headache types, such as migraine and tension-type headache (TTH), has been discussed for many years. Most results, however, were inconsistent and data on the association between lifestyle factors and probable headache forms are completely lacking. We evaluated the cross-sectional association between different lifestyle factors and headache subtypes using data from three different German cohorts. Information was assessed by standardized face-to-face interviews. Lifestyle factors included alcohol consumption, smoking status, physical activity and body mass index. According to the 2004 diagnostic criteria, we distinguished the following headache types: migraine, TTH and their probable forms. Regional variations of lifestyle factors were observed. In the age- and gender-adjusted logistic regression models, none of the lifestyle factors was statistically significant associated with migraine, TTH, and their probable headache forms. In addition, we found no association between headache subtypes and the health index representing the sum of individual lifestyle factors. The lifestyle factors such as alcohol consumption, smoking, physical activity and overweight seem to be unrelated to migraine and TTH prevalence. For a judgement on their role in the onset of new or first attacks of migraine or TTH (incident cases), prospective cohort studies are required