The solvability of groups with nilpotent minimal coverings

A covering of a group is a finite set of proper subgroups whose union is the whole group. A covering is minimal if there is no covering of smaller cardinality, and it is nilpotent if all its members are nilpotent subgroups. We complete a proof that every group that has a nilpotent minimal covering is solvable, starting from the previously known result that a minimal counterexample is an almost simple finite group

Venous thromboembolism and chronic venous disease among people who inject drugs: A systematic review and meta-analysis

Introduction Intravenous drug use continues to pose a substantial burden worldwide and little is known about the risk of venous thromboembolism (VTE) and its sequelae in people who inject drugs (PWID). Methods A systematic literature search was conducted on the prevalence of VTE and chronic venous disease in intravenous drug users, as well as on the prevalence of intravenous drug use among selected VTE patients. Two reviewers independently selected the articles and appraised their quality. A random-effect meta-analysis was performed to pool risks across studies. Results We included 18 studies with a total of 7691 patients. The overall prevalence of VTE among PWID was 29% (95%CI: 19–40%). Among patients diagnosed with VTE, 15% (95%CI: 10–20%) were PWID. Similar rates were confirmed in more recent studies published in the past decade, although these studies are often based on the general population from higher-risk areas. Reported rates of chronic venous disease ranged between 58% and 61%. The majority of the included studies had a low to moderate quality of evidence. We could not exclude a selection bias in the studies in geographical regions with high intravenous drug use prevalence. Conclusion VTE and chronic venous disease appear to be common and understudied complications of injective drug use. National programs for PWID patients should also focus on early and late VTE-associated complications

Ethical safety of deep brain stimulation: A study on moral decision-making in Parkinson's disease

INTRODUCTION: The possibility that deep brain stimulation (DBS) in Parkinson's disease (PD) alters patients' decisions and actions, even temporarily, raises important clinical, ethical and legal questions. Abnormal moral decision-making can lead to ethical rules violations. Previous experiments demonstrated the subthalamic (STN) activation during moral decision-making. Here we aim to study whether STN DBS can affect moral decision-making in PD patients. METHODS: Eleven patients with PD and bilateral STN DBS implant performed a computerized moral task in ON and OFF stimulation conditions. A control group of PD patients without DBS implant performed the same experimental protocol. All patients underwent motor, cognitive and psychological assessments. RESULTS: STN stimulation was not able to modify neither reaction times nor responses to moral task both when we compared the ON and the OFF state in the same patient (reaction times, p = .416) and when we compared DBS patients with those treated only with the best medical treatment (reaction times: p = .408, responses: p = .776). CONCLUSIONS: Moral judgment is the result of a complex process, requiring cognitive executive functions, problem-solving, anticipations of consequences of an action, conflict processing, emotional evaluation of context and of possible outcomes, and involving different brain areas and neural circuits. Our data show that STN DBS leaves unaffected moral decisions thus implying relevant clinical and ethical implications for DBS consequences on patients' behavior, on decision-making and on judgment ability. In conclusion, the technique can be considered safe on moral behavior

The ubiquitin ligase Mdm2 controls oligodendrocyte maturation by intertwining mTOR with G protein-coupled receptor kinase 2 in the regulation of GPR17 receptor desensitization

During oligodendrocyte precursor cell (OPC) differentiation, defective control of the membrane receptor GPR17 has been suggested to block cell maturation and impair remyelination under demyelinating conditions. After the immature oligodendrocyte stage, to enable cells to complete maturation, GPR17 is physiologically down-regulated via phosphorylation/desensitization by G protein-coupled receptor kinases (GRKs); conversely, GRKs are regulated by the "mammalian target of rapamycin" mTOR. However, how GRKs and mTOR are connected to each other in modulating GPR17 function and oligodendrogenesis has remained elusive. Here we show, for the first time, a role for Murine double minute 2 (Mdm2), a ligase previously involved in ubiquitination/degradation of the onco-suppressor p53 protein. In maturing OPCs, both rapamycin and Nutlin-3, a small molecule inhibitor of Mdm2-p53 interactions, increased GRK2 sequestration by Mdm2, leading to impaired GPR17 down-regulation and OPC maturation block. Thus, Mdm2 intertwines mTOR with GRK2 in regulating GPR17 and oligodendrogenesis and represents a novel actor in myelination

MUSE Analysis of Gas around Galaxies (MAGG) -- V: Linking ionized gas traced by CIV and SiIV absorbers to Lyα{\alpha} emitting galaxies at z≈3.0−4.5z\approx 3.0-4.5

We use 28 quasar fields with high-resolution (HIRES and UVES) spectroscopy from the MUSE Analysis of Gas Around Galaxies survey to study the connection between Ly${\alpha}$ emitters (LAEs) and metal-enriched ionized gas traced by CIV in absorption at redshift $z\approx3-4$. In a sample of 220 CIV absorbers, we identify 143 LAEs connected to CIV gas within a line-of-sight separation ${\rm \pm 500\,km\,s^{-1}}$, equal to a detection rate of $36\pm 5$ per cent once we account for multiple LAEs connected to the same CIV absorber. The luminosity function of LAEs associated with CIV absorbers shows a $\approx 2.4$ higher normalization factor compared to the field. CIV with higher equivalent width and velocity width are associated with brighter LAEs or multiple galaxies, while weaker systems are less often identified near LAEs. The covering fraction in groups is up to $\approx 3$ times larger than for isolated galaxies. Compared to the correlation between optically-thick HI absorbers and LAEs, CIV systems are twice less likely to be found near LAEs especially at lower equivalent width. Similar results are found using SiIV as tracer of ionized gas. We propose three components to model the gas environment of LAEs: i) the circumgalactic medium of galaxies, accounting for the strongest correlations between absorption and emission; ii) overdense gas filaments connecting galaxies, driving the excess of LAEs at a few times the virial radius and the modulation of the luminosity and cross-correlation functions for strong absorbers; iii) an enriched and more diffuse medium, accounting for weaker CIV absorbers farther from galaxies.Comment: 28 pages, 21 figures, 10 tables. Submitted to MNRAS after accounting for reviewer's comment

G PROTEIN-COUPLED RECEPTOR DESENSITISATION REGULATES STEM CELL DIFFERENTIATION

G-protein coupled receptors (GPCRs) play a key role in many complex biological processes, including regulation of stem cell pluripotency and differentiation. Signal transduction pathways that are activated during stem cell renewal and differentiation are shared, cross-activated or synergistic with GPCR stimulation [1]. Regulation of GPCR responses involved the activation of desensitization machinery, which started with phosphorylation of agonist-activated receptor by second messenger-dependent and/or GPCR kinases (GRKs)[1]. Besides controlling receptor responsiveness, GRKs can also act as agonist-regulated scaffolds assembling macromolecular signalosomes in the receptor environment, thereby contributing to signal propagation from cytosol to nucleus, and controlling gene transcription machinery [2]. Recent evidence suggests that the desensitization machinery fulfils a vital role in regulating cellular responses to GPCRs, and that changes in expression/functioning of these regulatory proteins may be crucial in the control of cell differentiation program [3]. These data are consistent with the notion that GPCR responsiveness may be differentially regulated during cell differentiation. In our hands, two different cellular models (oligodendrocyte precursor cells, OPCs, and mesenchymal stem cells, MSCs) were used to investigate the role of the GPCR desensitisation machinery in stem cell differentiation. During OPC differentiation, defective control of the membrane receptor GPR17 has been suggested to block cell maturation and impairs remyelination under demyelinating conditions [4]. Here we show, for the first time, a role for Murine double minute 2 (Mdm2), a ligase previously involved in ubiquitination/degradation of p53 protein. In maturing OPCs, the inhibition of Mdm2-p53 interactions increased GRK2 sequestration by Mdm2, leading to impaired GPR17 down-regulation and OPC maturation block. In MSCs, the A2B adenosine receptor (A2BAR) has been recently emerged as the major AR involved in osteoblastogenesis [5]. Proinflammatory cytokines, such as Tumour Necrosis Factor- (TNF-, have been demonstrated to regulate MSC differentiation and bone remodelling. Herein, we show that TNF- diminished GRK2 levels in MSCs, thus blocking A2BAR desensitization. As a result, TNF- enhanced the A2BAR-mediated responses and favoured MSC differentiation to osteoblasts in response to receptor agonists. The findings get new insights for discovering of the signals at the basis of cell differentiation

Nanoscale mapping of the conductivity and interfacial capacitance of an electrolyte-gated organic field-effect transistor under operation

Versió postprint del document publicat a: https://doi.org/10.1002/adfm.202008032Probing nanoscale electrical properties of organic semiconducting materials at the interface with an electrolyte solution under externally applied voltages is key in the field of organic bioelectronics. It is demonstrated that the conductivity and interfacial capacitance of the active channel of an electrolyte-gated organic field‐effect transistor (EGOFET) under operation can be probed at the nanoscale using scanning dielectric microscopy in force detection mode in liquid environment. Local electrostatic force versus gate voltage transfer characteristics are obtained on the device and correlated with the global current–voltage transfer characteristics of the EGOFET. Nanoscale maps of the conductivity of the semiconducting channel show the dependence of the channel conductivity on the gate voltage and its variation along the channel due to the space charge limited conduction. The maps reveal very small electrical heterogeneities, which correspond to local interfacial capacitance variations due to an ultrathin non-uniform insulating layer resulting from a phase separation in the organic semiconducting blend. Present results offer insights into the transduction mechanism at the organic semiconductor/electrolyte interfaces at scales down to ≈100 nm, which can bring substantial optimization of organic electronic devices for bioelectronic applications such as electrical recording on excitable cells or label-free biosensing

Resolving the physics of Quasar Lyα\alpha Nebulae (RePhyNe): I. Constraining Quasar host halo masses through Circumgalactic Medium kinematics

Ly$\alpha$ nebulae ubiquitously found around z>2 quasars can supply unique constraints on the properties of the Circumgalactic Medium, such as its density distribution, provided the quasar halo mass is known. We present a new method to constrain quasar halo masses based on the line-of-sight velocity dispersion maps of Ly$\alpha$ nebulae. By using MUSE-like mock observations obtained from cosmological hydrodynamic simulations under the assumption of maximal quasar fluorescence, we show that the velocity dispersion radial profiles of Ly$\alpha$-emitting gas are strongly determined by gravity and that they are thus self-similar with respect to halo mass when rescaled by the virial radius. Through simple analytical arguments and by exploiting the kinematics of HeII1640\.A emission for a set of observed nebulae, we show that Ly$\alpha$ radiative transfer effects plausibly do not change the shape of the velocity dispersion profiles but only their normalisation without breaking their self-similarity. Taking advantage of these results, we define the variable $\eta^{140-200}_{40-100}$ as the ratio of the median velocity dispersion in two specifically selected annuli and derive an analytical relation between $\eta^{140-200}_{40-100}$ and the halo mass which can be directly applied to observations. We apply our method to 37 observed quasar Ly$\alpha$ nebulae at 3<z<4.7 and find that their associated quasars are typically hosted by ~$10^{12.16 \pm 0.14}$ M$_{\odot}$ haloes independent of redshift within the explored range. This measurement, which is completely independent of clustering methods, is consistent with the lowest mass estimates based on quasar auto-correlation clustering at z~3 and with quasar-galaxies cross-correlation results.Comment: 23 pages, 13 figures, 2 tables. Accepted for publication in MNRA