Sticky physics of joy: On the dissolution of spherical candies

Assuming a constant mass-decrease per unit-surface and -time we provide a very simplistic model for the dissolution process of spherical candies. The aim is to investigate the quantitative behavior of the dissolution process throughout the act of eating the candy. In our model we do not take any microscopic mechanism of the dissolution process into account, but rather provide an estimate which is based on easy-to-follow calculations. Having obtained a description based on this calculation, we confirm the assumed behavior by providing experimental data of the dissolution process. Besides a deviation from our prediction caused by the production process of the candies below a diameter of 2 mm, we find good agreement with our model-based expectations. Serious questions on the optimal strategy of enjoying a candy will be addressed, like whether it is wise to split the candy by breaking it with the teeth or not

Nasal versus oronasal masks for home non-invasive ventilation in patients with chronic hypercapnia:a systematic review and individual participant data meta-analysis

BACKGROUND: The optimal interface for the delivery of home non-invasive ventilation (NIV) to treat chronic respiratory failure has not yet been determined. The aim of this individual participant data (IPD) meta-analysis was to compare the effect of nasal and oronasal masks on treatment efficacy and adherence in patients with COPD and obesity hypoventilation syndrome (OHS). METHODS: We searched Medline and Cochrane Central Register of Controlled Trials for prospective randomised controlled trials (RCTs) of at least 1 month's duration, published between January 1994 and April 2019, that assessed NIV efficacy in patients with OHS and COPD. The main outcomes were diurnal PaCO2, PaO2 and NIV adherence (PROSPERO CRD42019132398). FINDINGS: Of 1576 articles identified, 34 RCTs met the inclusion criteria and IPD were obtained for 18. Ten RCTs were excluded because only one type of mask was used, or mask data were missing. Data from 8 RCTs, including 290 IPD, underwent meta-analysis. Oronasal masks were used in 86% of cases. There were no differences between oronasal and nasal masks for PaCO2 (0.61 mm Hg (95% CI -2.15 to 3.38); p=0.68), PaO2 (-0.00 mm Hg (95% CI -4.59 to 4.58); p=1) or NIV adherence (0·29 hour/day (95% CI -0.74 to 1.32); p=0.58). There was no interaction between the underlying pathology and the effect of mask type on any outcome. INTERPRETATION: Oronasal masks are the most used interface for the delivery of home NIV in patients with OHS and COPD; however, there is no difference in the efficacy or tolerance of oronasal or nasal masks

Liver Fibrosis and Metabolic Alterations in Adults With alpha-1-antitrypsin Deficiency Caused by the Pi*ZZ Mutation

BACKGROUND & AIMS: Alpha-1 antitrypsin deficiency (AATD) is among the most common genetic disorders. Severe AATD is caused by a homozygous mutation in the SERPINA1 gene that encodes the Glu342Lys substitution (called the Pi*Z mutation, Pi*ZZ genotype). Pi*ZZ carriers may develop lung and liver diseases. Mutation- associated lung disorders have been well studied, but less is known about the effects in liver. We assessed the liver disease burden and associated features in adults with this form of AATD. METHODS: We collected data from 554 Pi*ZZ adults (403 in an exploratory cohort, 151 in a confirmatory cohort), in 9 European countries, with AATD who were homozygous for the Pi*Z mutation, and 234 adults without the Pi*Z mutation (controls), all without pre-existing liver disease. We collected data on demographic parameters, comorbidities, lung- and liver-related health, and blood samples for laboratory analysis. Liver fibrosis was assessed non-invasively via the serum tests Aspartate Aminotransferase to Platelet Ratio Index and HepaScore and via transient elastography. Liver steatosis was determined via transient elastography-based controlled attenuation parameter. We performed histologic analyses of livers from transgenic mice that overexpress the AATD-associated Pi*Z variant. RESULTS: Serum levels of liver enzymes were significantly higher in Pi*ZZ carriers vs controls. Based on non-invasive tests for liver fibrosis, significant fibrosis was suspected in 20%–36% of Pi*ZZ carriers, whereas signs of advanced fibrosis were 9- to 20-fold more common in Pi*ZZ carriers compared to non-carriers. Male sex; age older than 50 years; increased levels of alanine aminotransferase, aspartate aminotransferase, or g-glutamyl transferase; and low numbers of platelets were associated with higher liver fibrosis burden. We did not find evidence for a relationship between lung function and liver fibrosis. Controlled attenuation parameter 280 dB/m, suggesting severe steatosis, was detected in 39% of Pi*ZZ carriers vs 31% of controls. Carriers of Pi*ZZ had lower serum concentrations of triglyceride and low- and very-lowdensity lipoprotein cholesterol than controls, suggesting impaired hepatic secretion of lipid. Livers from Pi*Zoverexpressing mice had steatosis and down-regulation of genes involved in lipid secretion. CONCLUSIONS: In studies of AATD adults with the Pi*ZZ mutation, and of Pi*Z-overexpressing mice, we found evidence of liver steatosisinfo:eu-repo/semantics/publishedVersio

Bifurkációk neurális hálózatok Hopfield-modelljében

A Hopfiled-modell, egy visszacsatolt mesterséges neurális hálózatot leíró differenciálegyenlet-rendszer vizsgálatát végeztük bifurkációelméleti eszközökkel. A modellt speciális súlyozás mellett visszavezettük alacsonyabb dimenziós rendszerre, majd dinamikájának leírásához analitikus és numerikus eszközökkel lokális és globális bifurkációkat határoztunk meg. Leírást adtunk a rendszer lehetséges viselkedéseire a neuronok súlyainak függvényében a bifurkációs göbék által határolt tartományokban

Global bifurcations in a dynamical model of recurrent neural networks

summary:The dynamical behaviour of a continuous time recurrent neural network model with a special weight matrix is studied. The network contains several identical excitatory neurons and a single inhibitory one. This special construction enables us to reduce the dimension of the system and then fully characterize the local and global codimension-one bifurcations. It is shown that besides saddle-node and Andronov-Hopf bifurcations, homoclinic and cycle fold bifurcations may occur. These bifurcation curves divide the plane of weight parameters into nine domains. The phase portraits belonging to these domains are also characterized

Domiciliary Non-invasive Ventilation in COPD:An International Survey of Indications and Practices

Despite the fact that metanalyses and clinical guidelines do not recommend the routine use of domiciliary non-invasive ventilation (NIV) for patients diagnosed with severe stable Chronic Obstructive Pulmonary Disease (COPD) and with chronic respiratory failure, it is common practice in some countries.We conducted an international web-survey of physicians involved in provision of long-term NIV to examine patterns of domiciliary NIV use in patients diagnosed with COPD.The response rate was 41.6%. A reduction of hospital admissions, improvements in quality of life and dyspnea relief were considered as the main expected benefits for patients. Nocturnal oxygen saturation assessment was the principal procedure performed before NIV prescription. Recurrent exacerbations (>3) requiring NIV and failed weaning from in hospital NIV were the most important reasons for starting domiciliary NIV. Pressure support ventilation (PSV) was the most common mode, with low intensity settings (PSV-low) the most popular (44.4 30.1%) compared with high intensity (PSV-high) strategies (26.9 +/- 25.9%), with different geographical preferences.COPD is confirmed to be a common indication for domiciliary NIV. Recurrent exacerbations and failed weaning from in-hospital NIV were the main reasons for its prescription

Nasal versus oronasal masks for home non-invasive ventilation in patients with chronic hypercapnia: a systematic review and individual participant data meta-analysis

International audienc