A Leaky Wave Antenna Design Based on Half-mode Substrate Integrated Waveguide Technology for X Band Applications

A new type of leaky-wave antenna (LWA) using half-mode substrate integrated waveguide (HMSIW) as the base structure is proposed in this paper. The structure consists of an array of slot, antenna designed to operate in X band applications from 8 to 12 GHz. HMSIW preserves nearly all the advantages of SIW whereas its size is nearly reduced by half. The antenna radiates one main beam that can be steered from the backward to the forward direction by changing frequency

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

Monitoring of complex gear system by synchronous cepstral analysis

This article shows the possibilities offered by the use of energy cepstrum for gear box vibratory diagnosis . A model of the signals generated by an accelerometric sensor will be established on which the theoretical expression of the energy cepstrum is partially calculated . This will make it possible to develop a detection tool which we will nether be affected by the signal amplitude, nor the noise to signal ratio nor the position of the sensor . It is shown that the use of an angular sampled signal enables the cepstrum to preserve its full resolution and allows the realization of synchronous averaging to isolate each gear mesh . Some applications of the monitoring procedure are presented .Dans cet article nous étudions les possibilités offertes par le cepstre d'énergie en diagnostic vibratoire des réducteurs à engrenages. Nous présentons un modèle approché de structure des signaux issus d'un capteur accélérométrique, à partir duquel nous calculons partiellement l'expression théorique du cepstre d'énergie. Cette expression nous permet de définir un révélateur de défauts indépendant de l'amplitude des signaux, du rapport signal à bruit et de la position du capteur. Nous montrons que l'utilisation de signaux acquis sous échantillonnage angulaire permet au cepstre de conserver sa résolution maximale et autorise la réalisation de moyennes synchrones pour isoler chaque engrènement d'un réducteur complexe. Enfin nous présentons quelques applications de notre procédure de surveillance

Pig immune response to general stimulus and to porcine reproductive and respiratory syndrome virus infection: a meta-analysis approach

BACKGROUND: The availability of gene expression data that corresponds to pig immune response challenges provides compelling material for the understanding of the host immune system. Meta-analysis offers the opportunity to confirm and expand our knowledge by combining and studying at one time a vast set of independent studies creating large datasets with increased statistical power. In this study, we performed two meta-analyses of porcine transcriptomic data: i) scrutinized the global immune response to different challenges, and ii) determined the specific response to Porcine Reproductive and Respiratory Syndrome Virus (PRRSV) infection. To gain an in-depth knowledge of the pig response to PRRSV infection, we used an original approach comparing and eliminating the common genes from both meta-analyses in order to identify genes and pathways specifically involved in the PRRSV immune response. The software Pointillist was used to cope with the highly disparate data, circumventing the biases generated by the specific responses linked to single studies. Next, we used the Ingenuity Pathways Analysis (IPA) software to survey the canonical pathways, biological functions and transcription factors found to be significantly involved in the pig immune response. We used 779 chips corresponding to 29 datasets for the pig global immune response and 279 chips obtained from 6 datasets for the pig response to PRRSV infection, respectively. RESULTS: The pig global immune response analysis showed interconnected canonical pathways involved in the regulation of translation and mitochondrial energy metabolism. Biological functions revealed in this meta-analysis were centred around translation regulation, which included protein synthesis, RNA-post transcriptional gene expression and cellular growth and proliferation. Furthermore, the oxidative phosphorylation and mitochondria dysfunctions, associated with stress signalling, were highly regulated. Transcription factors such as MYCN, MYC and NFE2L2 were found in this analysis to be potentially involved in the regulation of the immune response. The host specific response to PRRSV infection engendered the activation of well-defined canonical pathways in response to pathogen challenge such as TREM1, toll-like receptor and hyper-cytokinemia/ hyper-chemokinemia signalling. Furthermore, this analysis brought forth the central role of the crosstalk between innate and adaptive immune response and the regulation of anti-inflammatory response. The most significant transcription factor potentially involved in this analysis was HMGB1, which is required for the innate recognition of viral nucleic acids. Other transcription factors like interferon regulatory factors IRF1, IRF3, IRF5 and IRF8 were also involved in the pig specific response to PRRSV infection. CONCLUSIONS: This work reveals key genes, canonical pathways and biological functions involved in the pig global immune response to diverse challenges, including PRRSV infection. The powerful statistical approach led us to consolidate previous findings as well as to gain new insights into the pig immune response either to common stimuli or specifically to PRRSV infection

Lanthanides compete with calcium for binding to cadherins and inhibit cadherin-mediated cell adhesion

Lanthanides are rare-earth metals with a broad range of applications in biological research and medicine. In addition to their unique magnetic and spectroscopic properties, lanthanides are also effective mimics of calcium and can stimulate or inhibit the function of calcium-binding proteins. Cadherins are a large family of calcium-binding proteins that facilitate cell adhesion and play key roles in embryo development, tissue homeostasis and tumour metastasis. However, whether lanthanides can bind cadherins and functionally replace calcium binding has not been comprehensively explored. In this study, we investigated the effect of lanthanide binding on cadherin structure and function using terbium, which is a commonly used lanthanide for protein spectroscopy and a proposed anti-cancer agent. We demonstrate that terbium can compete with calcium for binding to calcium-binding sites in cadherins. Terbium binding to cadherins abolished their cell adhesive activity and rendered cadherins sensitive to proteolysis by trypsin. Molecular dynamics simulations indicate that replacement of calcium by terbium results in structural rearrangements and increases the flexibility of the cadherin ectodomain. These changes in structure and dynamics are likely to underlie the inability of lanthanide-bound cadherins to support cell adhesion. Taken together, our findings further knowledge on lanthanide interactions with calcium-binding proteins and provide new insight into the influence of metal chemistry on cadherin structure, dynamics and function

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

Diagnostic d'un train d'engrenages par analyse cepstrale synchrone

Nous exposons dans cet article nos résultats concernant l'acquisition et le traitement de signaux vibratoires issus d'accéléromètres placés sur des réducteurs à engrenages. Nous montrons que l'analyse cepstrale pratiquée sur des signaux obtenus sous échantillonnage angulaire peut constituer un outil de diagnostic simple et efficace. Nous avons calculé la contribution au cepstre de la modulation due à plusieurs périodes de rotation. Nous montrons que la somme des premiers pics cepstraux associés à chaque période est constante. Ce fait est confirmé par les résultats expérimentaux