The formal sector wage premium and firm size

We show theoretically that when larger firms pay higher wages and are more likely to be caught defaulting on labour taxes, then large high-wage firms will be in the formal sector and small low-wage firms will be in the informal sector. The formal sector wage premium is thus just a firm size wage differential. Using data from the South African labour force survey we illustrate that firm size is indeed the key variable determining whether a formal sector premium exists

3D CATBraTS: Channel Attention Transformer for Brain Tumour Semantic Segmentation

Brain tumour diagnosis is a challenging task yet crucial for planning treatments to stop or slow the growth of a tumour. In the last decade, there has been a dramatic increase in the use of convolutional neural networks (CNN) for their high performance in the automatic segmentation of tumours in medical images. More recently, Vision Transformer (ViT) has become a central focus of medical imaging for its robustness and efficiency when compared to CNNs. In this paper, we propose a novel 3D transformer named 3D CATBraTS for brain tumour semantic segmentation on magnetic resonance images (MRIs) based on the state-of-the-art Swin transformer with a modified CNN-encoder architecture using residual blocks and a channel attention module. The proposed approach is evaluated on the BraTS 2021 dataset and achieved quantitative measures of the mean Dice similarity coefficient (DSC) that surpasses the current state-of-the-art approaches in the validation phase

Development of mathematical models for predicting the iron concentrations of Lake Oubeira waters (ne Algerian)

Facing the increase of surface water samples contaminated by ETMs, usually from the geochemical background, the emergence of new human diseases is worrying. To solve this problem, we have developed several models based on different learning algorithms qualified by high performance, using different transfer functions. We have shown that all the Neural Models presented more or less important performance  compared to the one based on multiple linear regressions. The best revealed model ANN in the current work is a MLP type that uses the Levenberg-Marquardt algorithm as a learning algorithm, with Tansig and Purelin as transfer functions, respectively in the hidden layer and the output layer. This successful model can be considered as an important tool of great effectiveness in the context of environmental prediction and especially in anticipation of the iron contents of the Oubeira Lake water.Keywords: Prediction, heavy metals, Linear multiple regression, artificial neural  networks, Oubéira Lake

Milling cutting tool diagnosis using comparisons of the excitation identified by cepstral techniques

This paper investigates the diagnosis of cutting tools in a milling operation using vibration signals and proposes a signal processing algorithm to achieve that. In the proposed algorithm, the impulse response of the measured vibration signal is firstly identified using the random decrement technique. This is then converted to a cepstrum and subtracted from the measured signal in the quefrency domain using the additive properties of cepstra. The residual signal representing the forcing function is then transformed back into the time domain using the inverse cepstrum. Finally the power spectral density is estimated, and a comparison is made between the different states of the cutting tool. For a good estimation of the force, four measurement points are used, and the identified excitation sources are then averaged. By comparing the spectra of the forcing functions, the efficiency of the method is demonstrated, and the faulty case is clearly distinguished from the fault-free case. This was not the case with the original response signals

Fresh, hardened and durability properties of sodium carbonate-activated Algerian slag exposed to sulfate and acid attacks

This paper investigates the use of Na2CO3 as an alkaline activator on the durability of the alkali-activated slag (AAS) mortar toward sulfates and acids. The behavior of this binder in these aggressive environments is compared to those of slags activated with Na2SiO3 and NaOH. In addition, the setting times, workabilities, mechanical properties and drying shrinkage were evaluated. The AAS had superior workabilities, faster setting times and higher shrinkage rates than the Portland cement (PC). Increases in the activator dosages had positive effects on the mechanical strengths of the materials. Na2SiO3 was the best activator in terms of strength development, but it led to much higher shrinkage. The AAS showed less expansion and lower weight losses than the PC when exposed to sulfate and acids, respectively. The Na2CO3-AAS exhibited less shrinkage and higher resistance to sulfuric acid than the other activators, but the mechanical strength seen at early ages was low

Structural basis of second-generation HIV integrase inhibitor action and viral resistance

Despite worldwide prescription, the mechanistic basis for superiority of second-generation HIV integrase (IN) strand transfer inhibitors (INSTIs) is poorly understood. We use single-particle cryo-electron microscopy to visualize the mode of action of the advanced INSTIs dolutegravir and bictegravir at near atomic resolution. Q148H/G140S amino acid substitutions in IN that pervade clinical INSTI failure perturb optimal magnesium ion coordination in the enzyme active site. The expanded chemical scaffolds of second-generation compounds mediate interactions with the protein backbone, which are critical for antagonizing Q148H/G140S mutant virus. Our results reveal that binding to magnesium ions underpins a fundamental weakness of the INSTI pharmacophore that is exploited by the virus to engender resistance and provide a structural framework for the development of this important class of anti-HIV/AIDS therapeutics

‘The phoenix that always rises from the ashes’: an exploratory qualitative study of the experiences of an initiative informed by principles of psychological first aid following the Beirut blast

BACKGROUND: On 4 August 2020, an explosion occurred in Beirut, Lebanon. Hundreds of people were killed, thousands injured and displaced. An initiative was rapidly initiated to provide remote support informed by psychological first aid for the mental health of Lebanese young adults affected by the blast. However, little is known about recipients’ experiences of such initiatives. OBJECTIVES: This study aimed to qualitatively explore the experiences of supporters and recipients in the community-led initiative following the blast. METHOD: We recruited a diverse sample of four supporters and four Lebanese recipients who took part in the Beirut initiative. Semi-structured interviews were conducted with participants. Reflexive thematic analysis was used to analyse the qualitative data. RESULTS: We developed five themes from the qualitative interviews, which highlighted ideas around accessibility, alienation, the relationship, elements of the safe space created by the initiative, and unmet needs and areas for improvement. Recipients described the detrimental impact of the blast on their mental health within the Lebanese context and beyond. Recipients and supporters elucidated complex experiences of the support and its impact. CONCLUSIONS: Our findings suggest remote support has the potential to be acceptable for young adults in Lebanon. Further research into support informed by psychological first aid after similar crisis events is warranted