Using 808 nm NIR Laser, a cost effective FSO communication channel has been established. Scintillation, the phenomenon, which is produced by the heating effect, affects the FSO communication channel ...severely. As a result, the communication channel performance has degraded. For investigation the scintillation effect upon the 808 nm FSO link, a 40 ft. artificial chamber has been made for scintillation simulation in the laboratory. From very high to low scintillation effect has been created in the artificial chamber, and a 10 MHz On–Off Keying modulated optical signal has been taken for testing. The optical power attenuation, the real time eye pattern has been measured for different types of scintillation effect. Applying the aperture averaging scheme, a significant amount of optical power attenuation has been reduced, as a result, the value of signal to noise ratio (SNR) has been increased and the channel performance has been improved significantly.
The forecast of rain rate and the accompanying attenuation is a crucial factor for analyzing the efficacy of a terrestrial-based ‘Free Space Optical’ communication technology. The optical beam in a ...terrestrial-based FSO communication system commonly propagates through open air, where it is susceptible to atmospheric hazards like rain, dust, fog, snow, etc., as a result, the optical beam is diminished by these hazards. In this paper, experimentation has been carried out in the developed artificial rain simulation chamber with a 980 nm Laser source. The considered modulated Laser beam propagates in the different rain rates that are generated by the artificial rain simulation chamber. The obtained optical power attenuation for wavelength (980 nm) is compared with other existing conventional models and developed a new rain attenuation model. With the research of optical power attenuation, the impact of various rain rates on communication channels has been investigated as well, and eventually, an optical power attenuation mitigation strategy known as the "Aperture Averaging" technique has been Introduced in the system. As a consequence, the optical link performance has been improved significantly in terms of received optical power, signal-to-noise ratio, bit error rate, etc., at different rain rate scenarios.
On the “Free Space Optical” (FSO) communication link, the atmospheric scintillation phenomena play a crucial role. The severity of the scintillation can seriously impair the FSO link’s performance. ...In this article, we consider two wavelengths of FSO link, visible (638 nm) and infrared (980 nm), and measure their performances in a developed artificial scintillation simulation chamber, with the severity of scintillation ranged from low to high. The link performance is measured in terms of the eye pattern, optical power attenuation, signal-to-noise ratio (SNR), bit error rate (BER), etc., at the receiver side signal. As compared to the visible wavelength, 980 nm produces favorable performance in the high scintillation regime.
This article deals with the proposed design of a 10 GHz optical wireless communication (OWC) link using 1550 nm Laser source for long range communication channel. Optical communication is the ...backbone of next generation gigabit class communication system and optical fiber communication plays an important role to fulfill the requirement of gigabit communication. But OWC is very useful where optical fibers cannot be laid off. A 10 GHz communication channel bandwidth has been designed in this article using very low power (2 mW) 1550 nm laser diode. A long range communication channel of 3 km has been considered with maximum bit-error-rate (BER) of 10−9. This system has been designed to withstand high atmospheric attenuation up to 11.67 dB/km, without affecting the BER and link range. An auto alignment method and automatic laser power control method have also been described with all necessary design parameters of the system.
The high level of functional diversity and plasticity in monocytes/macrophages has been defined within in vitro systems as M1 (classically activated), M2 (alternatively activated) and deactivated ...macrophages, of which the latter two subtypes are associated with suppression of cell mediated immunity, that confers susceptibility to intracellular infection. Although the Leishmania parasite modulates macrophage functions to ensure its survival, what remains an unanswered yet pertinent question is whether these macrophages are deactivated or alternatively activated. This study aimed to characterize the functional plasticity and polarization of monocytes/macrophages and delineate their importance in the immunopathogenesis of Post kala-azar dermal leishmaniasis (PKDL), a chronic dermatosis of human leishmaniasis. Monocytes from PKDL patients showed a decreased expression of TLR-2/4, along with an attenuated generation of reactive oxidative/nitrosative species. At disease presentation, an increased mRNA expression of classical M2 markers CD206, ARG1 and PPARG in monocytes and lesional macrophages indicated M2 polarization of macrophages which was corroborated by increased expression of CD206 and arginase-1. Furthermore, altered vitamin D signaling was a key feature in PKDL, as disease presentation was associated with raised plasma levels of monohydroxylated vitamin D3 and vitamin D3- associated genes, features of M2 polarization. Taken together, in PKDL, monocyte/macrophage subsets appear to be alternatively activated, a phenotype that might sustain disease chronicity. Importantly, repolarization of these monocytes to M1 by antileishmanial drugs suggests that switching from M2 to M1 phenotype might represent a therapeutic opportunity, worthy of future pharmacological consideration.
Accumulation of activated neutrophils at the feto-maternal interface is a defining hallmark of intrauterine inflammation (IUI) that might trigger an excessive immune response during pregnancy. ...Mechanisms responsible of this massive neutrophil recruitment are poorly investigated. We have previously showed that intraamniotic injection of LPS in rhesus macaques induced a neutrophil predominant inflammatory response similar to that seen in human IUI. Here, we demonstrate that anti-TNF antibody (Adalimumab) inhibited ~80% of genes induced by LPS involved in inflammatory signaling and innate immunity in chorio-decidua neutrophils. Consistent with the gene expression data, TNF-blockade decreased LPS-induced neutrophil accumulation and activation at the feto-maternal interface. We also observed a reduction in IL-6 and other pro-inflammatory cytokines but not prostaglandins concentrations in the amniotic fluid. Moreover, TNF-blockade decreased mRNA expression of inflammatory cytokines in the chorio-decidua but not in the uterus, suggesting that inhibition of TNF-signaling decreased the inflammation in a tissue-specific manner within the uterine compartment. Taken together, our results demonstrate a predominant role for TNF-signaling in modulating the neutrophilic infiltration at the feto-maternal interface during IUI and suggest that blockade of TNF-signaling could be considered as a therapeutic approach for IUI, the major leading cause of preterm birth.
Post Kala-azar dermal leishmaniasis (PKDL), caused by Leishmania donovani is the dermal sequel of Visceral Leishmaniasis and importantly, is the proposed disease reservoir. The survival of Leishmania ...parasites within monocytes/macrophages hinges on its ability to effectively nullify immune activation mechanisms. Thus, delineating the disease-promoting immune mechanisms can facilitate development of immunotherapeutic strategies. Accordingly, in the absence of an animal model, this study aimed to delineate the status of CD8
T-cells in patients with PKDL. At disease presentation, the absence of CD4
T-cells at lesional sites was concomitant with an overwhelming infiltration of CD8
T-cells that demonstrated an absence of Perforin, Granzyme and Zap-70, along with an enhanced expression of Programmed Death-1 (PD-1) and the skin-homing CCL17. Additionally, the lesional CCR4
CD8
population was associated with an enhanced expression of IL-10 and IL-5. In circulation, the enhanced CD8
CCR4
T-cell population and raised levels of CCL17/22 was associated with an increased frequency of PD-1, while CD127 was decreased. Taken together, in PKDL, the enhanced plasma and lesional CCL17 accounted for the dermal homing of CD8
CCR4
T-cells, that along with a concomitant upregulation of PD-1 and IL-10 mediated immune inactivation, emphasizing the need for designing immunotherapies capable of reinvigorating T-cell potency.
Chorioamnionitis, a potentially serious inflammatory complication of pregnancy, is associated with the development of an inflammatory milieu within the amniotic fluid surrounding the developing ...fetus. When chorioamnionitis occurs, the fetal lung finds itself in the unique position of being constantly exposed to the consequent inflammatory meditators and/or microbial products found in the amniotic fluid. This exposure results in significant changes to the fetal lung, such as increased leukocyte infiltration, altered cytokine, and surfactant production, and diminished alveolarization. These alterations can have potentially lasting impacts on lung development and function. However, studies to date have only begun to elucidate the association between such inflammatory exposures and lifelong consequences such as lung dysfunction. In this review, we discuss the pathogenesis of and fetal immune response to chorioamnionitis, detail the consequences of chorioamnionitis exposure on the developing fetal lung, highlighting the various animal models that have contributed to our current understanding and discuss the importance of fetal exposures in regard to the development of chronic respiratory disease. Finally, we focus on the clinical, basic, and therapeutic challenges in fetal inflammatory injury to the lung, and propose next steps and future directions to improve our therapeutic understanding of this important perinatal stress.
During infections involving intracellular pathogens, iron performs a double-edged function by providing the pathogen with nutrients, but also boosts the host's antimicrobial arsenal. Although the ...role of iron has been described in visceral leishmaniasis, information regarding its status in the dermal sequel, Post Kala-azar Dermal Leishmaniasis (PKDL) remains limited. Accordingly, this study aimed to establish the status of iron within monocytes/macrophages of PKDL cases.
The intramonocytic labile iron pool (LIP), status of CD163 (hemoglobin-haptoglobin scavenging receptor) and CD71 (transferrin receptor, Tfr) were evaluated within CD14+ monocytes by flow cytometry, and soluble CD163 by ELISA. At the lesional sites, Fe3+ status was evaluated by Prussian blue staining, parasite load by qPCR, while the mRNA expression of Tfr (TfR1/CD71), CD163, divalent metal transporter-1 (DMT-1), Lipocalin-2 (Lcn-2), Heme-oxygenase-1 (HO-1), Ferritin, Natural resistance-associated macrophage protein (NRAMP-1) and Ferroportin (Fpn-1) was evaluated by droplet digital PCR. Circulating monocytes demonstrated elevated levels of CD71, CD163 and soluble CD163, which corroborated with an enhanced lesional mRNA expression of TfR, CD163, DMT1 and Lcn-2. Additionally, the LIP was raised along with an elevated mRNA expression of ferritin and HO-1, as also iron exporters NRAMP-1 and Fpn-1.
In monocytes/macrophages of PKDL cases, enhancement of the iron influx gateways (TfR, CD163, DMT-1 and Lcn-2) possibly accounted for the enhanced LIP. However, enhancement of the iron exporters (NRAMP-1 and Fpn-1) defied the classical Ferritinlow/Ferroportinhigh phenotype of alternatively activated macrophages. The creation of such a pro-parasitic environment suggests incorporation of chemotherapeutic strategies wherein the availability of iron to the parasite can be restricted.
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