Controlling water giant low-inertia nonlinear refractive index in the THz frequency range via temperature variation.

To create self-controlled radiation photonics systems, it is necessary to have complete information about the nonlinear properties of the materials used. In this Letter, the vibrational mechanism of the giant low-inertia cubic nonlinearity of the refractive index of water in the terahertz (THz) frequency range is experimentally proven. Its dominance, which manifests itself when the temperature of the liquid changes, is demonstrated. The measured nonlinear refractive index in the THz frequency range for a water jet at temperatures from 14°C to 21°C demonstrates a correlation with the theoretical approach, varies in the range 4-10 × 10-10 cm2/W, and is characterized by an inertial time constant of less than 1 ps.

Vanishing Confinement Regime in Terahertz HgTe Nanocrystals Studied under Extreme Conditions of Temperature and Pressure.

While HgTe nanocrystals (NCs) in the mid-infrared region have reached a high level of maturity, their far-infrared counterparts remain far less studied, raising the need for an in-depth investigation of the material before efficient device integration can be considered. Here, we explore the effect of temperature and pressure on the structural, spectroscopic, and transport properties of HgTe NCs displaying an intraband absorption at 10 THz. The temperature leads to a very weak modulation of the spectrum as opposed to what was observed for strongly confined HgTe NCs. HgTe NC films present ambipolar conduction with a clear prevalence of electron conduction as confirmed by transistor and thermoelectric measurements. Under the application of pressure, the material undergoes phase transitions from the zinc blende to cinnabar phase and later to the rock salt phase which we reveal using joint X-ray diffraction and infrared spectroscopy measurements. We discuss how the pressure existence domain of each phase is affected by the particle size.

Radiation shift from triple to quadruple frequency caused by the interaction of terahertz pulses with a nonlinear Kerr medium.

High-intensity optical radiation propagation in a transparent dielectric medium causes the phenomena of pulse self-action and radiation generation at triple frequencies due to the cubic nonlinearity of the medium. However, quadratic nonlinear effects usually outshine the cubic ones in anisotropic nonlinear crystals. In this work, we demonstrate that for certain experimental parameters the nonlinear effect of the third order can be stronger than the second order one in the MgO:[Formula: see text] crystal for terahertz frequency range. We experimentally and theoretically show that this effect can lead to the significant modification of the classical phenomenon of radiation generation at triple frequencies in the case when the pulse represents only one complete oscillation of the optical field. The experiment demonstrated that the phenomenon of generation of radiation at triple frequencies with respect to the frequency of the maximum spectral density in a nonlinear medium of the pulse disappears, and it is replaced by the generation of radiation at quadruple frequencies. The analysis confirms that this effect is based on the asymmetry and large width of the initial spectrum of such extremely short pulses in terms of the number of oscillations.

Air-Oxygen Blenders for Mechanical Ventilators: A Literature Review.

Respiratory diseases are one of the most common causes of death in the world and this recent COVID-19 pandemic is a key example. Problems such as infections, in general, affect many people and depending on the form of transmission they can spread throughout the world and weaken thousands of people. Two examples are severe acute respiratory syndrome and the recent coronavirus disease. These diseases have mild and severe forms, in which patients gravely affected need ventilatory support. The equipment that serves as a basis for operation of the mechanical ventilator is the air-oxygen blender, responsible for carrying out the air-oxygen mixture in the proper proportions ensuring constant supply. New blender models are described in the literature together with applications of control techniques, such as Proportional, Integrative and Derivative (PID); Fuzzy; and Adaptive. The results obtained from the literature show a significant improvement in patient care when using automatic controls instead of manual adjustment, increasing the safety and accuracy of the treatment. This study presents a deep review of the state of the art in air-oxygen benders, identifies the most relevant characteristics, performs a comparison study considering the most relevant available solutions, and identifies open research directions in the topic.

Lightweight and Efficient Dynamic Cluster Head Election Routing Protocol for Wireless Sensor Networks.

Wireless Sensor Networks (WSNs) have gained great significance from researchers and industry due to their wide applications. Energy and resource conservation challenges are facing the WSNs. Nevertheless, clustering techniques offer many solutions to address the WSN issues, such as energy efficiency, service redundancy, routing delay, scalability, and making WSNs more efficient. Unfortunately, the WSNs are still immature, and suffering in several aspects. This paper aims to solve some of the downsides in existing routing protocols for WSNs; a Lightweight and Efficient Dynamic Cluster Head Election routing protocol (LEDCHE-WSN) is proposed. The proposed routing algorithm comprises two integrated methods, electing the optimum cluster head, and organizing the re-clustering process dynamically. Furthermore, the proposed protocol improves on others present in the literature by combining the random and periodic electing method in the same round, and the random method starts first at the beginning of each round/cycle. Moreover, both random and periodic electing methods are preceded by checking the remaining power to skip the dead nodes and continue in the same way periodically with the rest of the nodes in the round. Additionally, the proposed protocol is distinguished by deleting dead nodes from the network topology list during the re-clustering process to address the black holes and routing delay problems. Finally, the proposed algorithm's mathematical modeling and analysis are introduced. The experimental results reveal the proposed protocol outperforms the LEACH protocol by approximately 32% and the FBCFP protocol by 8%, in terms of power consumption and network lifetime. In terms of Mean Package Delay, LEDCHE-WSN improves the LEACH protocol by 42% and the FBCFP protocol by 15%, and regarding Loss Ratio, it improves the LEACH protocol by approximately 46% and FBCFP protocol by 25%.

Compression-Aware Aggregation and Energy-Aware Routing in IoT-Fog-Enabled Forest Environment.

Forest fire monitoring is very much needed for protecting the forest from any kind of disaster or anomaly leading to the destruction of the forest. Now, with the advent of Internet of Things (IoT), a good amount of research has been done on energy consumption, coverage, and other issues. These works did not focus on forest fire management. The IoT-enabled environment is made up of low power lossy networks (LLNs). For improving the performance of routing protocol in forest fire management, energy-efficient routing protocol for low power lossy networks (E-RPL) was developed where residual power was used as an objective function towards calculating the rank of the parent node to form the destination-oriented directed acyclic graph (DODAG). The challenge in E-RPL is the scalability of the network resulting in a long end-to-end delay and less packet delivery. Additionally, the energy of sensor nodes increased with different transmission range. So, for obviating the above-mentioned drawbacks in E-RPL, compressed data aggregation and energy-based RPL routing (CAA-ERPL) is proposed. The CAA-ERPL is compared with E-RPL, and the performance is analyzed resulting in reduced packet transfer delay, less energy consumption, and increased packet delivery ratio for 10, 20, 30, 40, and 50 nodes. This has been evaluated using a Contiki Cooja simulator.

Formation of gigahertz pulse train by chirped terahertz pulses interference.

The state-of-art broadband THz sources can contribute to the development of short-range 6G communications. This paper has demonstrated the feasibility of forming the controllable sequence of THz subpulses in the temporal domain and the corresponding quasidiscrete spectrum by the interference of two THz pulses with an exponential chirp. Moreover, due to small time delay between these pulses the temporal and spectral structures are similar to each other (so-called "linkage relation"). This will benefit information encoding in the THz range. The calculated metrics for the prototype communication channel based on the proposed method are competitive with existing short-range THz CW channels.

Looking at Fog Computing for E-Health through the Lens of Deployment Challenges and Applications.

Fog computing is a distributed infrastructure where specific resources are managed at the network border using cloud computing principles and technologies. In contrast to traditional cloud computing, fog computing supports latency-sensitive applications with less energy consumption and a reduced amount of data traffic. A fog device is placed at the network border, allowing data collection and processing to be physically close to their end-users. This characteristic is essential for applications that can benefit from improved latency and response time. In particular, in the e-Health field, many solutions rely on real-time data to monitor environments, patients, and/or medical staff, aiming at improving processes and safety. Therefore, fog computing can play an important role in such environments, providing a low latency infrastructure. The main goal of the current research is to present fog computing strategies focused on electronic-Health (e-Health) applications. To the best of our knowledge, this article is the first to propose a review in the scope of applications and challenges of e-Health fog computing. We introduce some of the available e-Health solutions in the literature that focus on latency, security, privacy, energy efficiency, and resource management techniques. Additionally, we discuss communication protocols and technologies, detailing both in an architectural overview from the edge devices up to the cloud. Differently from traditional cloud computing, the fog concept demonstrates better performance in terms of time-sensitive requirements and network data traffic. Finally, based on the evaluation of the current technologies for e-Health, open research issues and challenges are identified, and further research directions are proposed.

A Smart Waste Management Solution Geared towards Citizens.

Global industry is undergoing major transformations with the genesis of a new paradigm known as the Internet of Things (IoT) with its underlying technologies. Many company leaders are investing more effort and money in transforming their services to capitalize on the benefits provided by the IoT. Thereby, the decision makers in public waste management do not want to be outdone, and it is challenging to provide an efficient and real-time waste management system. This paper proposes a solution (hardware, software, and communications) that aims to optimize waste management and include a citizen in the process. The system follows an IoT-based approach where the discarded waste from the smart bin is continuously monitored by sensors that inform the filling level of each compartment, in real-time. These data are stored and processed in an IoT middleware providing information for collection with optimized routes and generating important statistical data for monitoring the waste collection accurately in terms of resource management and the provided services for the community. Citizens can easily access information about the public waste bins through the Web or a mobile application. The creation of the real prototype of the smart container, the development of the waste management application and a real-scale experiment use case for evaluation, demonstration, and validation show that the proposed system can efficiently change the way people deal with their garbage and optimize economic and material resources.

Blockchain in Smart Grids: A Review on Different Use Cases.

With the integration of Wireless Sensor Networks and the Internet of Things, the smart grid is being projected as a solution for the challenges regarding electricity supply in the future. However, security and privacy issues in the consumption and trading of electricity data pose serious challenges in the adoption of the smart grid. To address these challenges, blockchain technology is being researched for applicability in the smart grid. In this paper, important application areas of blockchain in the smart grid are discussed. One use case of each area is discussed in detail, suggesting a suitable blockchain architecture, a sample block structure and the potential blockchain technicalities employed in it. The blockchain can be used for peer-to-peer energy trading, where a credit-based payment scheme can enhance the energy trading process. Efficient data aggregation schemes based on the blockchain technology can be used to overcome the challenges related to privacy and security in the grid. Energy distribution systems can also use blockchain to remotely control energy flow to a particular area by monitoring the usage statistics of that area. Further, blockchain-based frameworks can also help in the diagnosis and maintenance of smart grid equipment. We also discuss several commercial implementations of blockchain in the smart grid. Finally, various challenges to be addressed for integrating these two technologies are discussed.

Impact of laser-ionized liquid nonlinear characteristics on the efficiency of terahertz wave generation.

The generation of terahertz (THz) radiation during the propagation of subpicosecond pulses in liquid media is investigated using a theoretical model considering the relative contribution of Kerr and plasma nonlinearity. The dependences of the THz emission generation efficiency on the contribution of plasma nonlinearity with a fixed third-order nonlinearity value revealed the existence of weak and strong ionization modes. It is shown that the transition between these modes is determined by the ratio of plasma to Kerr nonlinearity coefficients and the pump energy. In the strong ionization mode and with the fixed contribution of plasma nonlinearity, the optical-to-THz conversion efficiency decreases with increasing Kerr nonlinearity due to the redistribution of the pump energy for the third-order effects. These results contribute to estimating the potential of liquid media as highly efficient THz sources.

Double-pump technique - one step closer towards efficient liquid-based THz sources.

By irradiating a water jet with double pulses, we demonstrate 4-fold higher THz wave generation than for a single pump pulse. The dependence of the enhanced THz signal on the temporal delay between two collinear pulses reveals the optimal time for launching signal pulse is near 2-4 ps, which corresponds to the time needed to create the complete pre-ionization state when sufficient electron density is already induced, and there is no plasma reflection of the pump pulse radiation. The increase in THz waves generation efficiency corresponds to the case of water jet excitation by the pulses with an optimal duration for a certain jet thickness, which is determined by the spatial pulse size. Using a theoretical model of the interaction of a high-intensity sub-picosecond pulse with an isotropic medium, we held a numerical simulation, which well describes the experimental results when using 3 ps value of population relaxation time. Thus, in this work, double pump method allows not only to increase the energy of the generated THz waves, but also to determine the characteristic excited state lifetime of liquid water. The optical-to-terahertz conversion efficiency in case of double pulse excitation of water column is of the order of 0.5⋅10 -3, which exceeds the typical values for THz waves generation during two-color filamentation in air and comparable with the achievable values due to the optical rectification in some crystals.

Flat liquid jet as a highly efficient source of terahertz radiation.

Polar liquids are strong absorbers of electromagnetic waves in the terahertz range, therefore, historically such liquids have not been considered as good candidates for terahertz sources. However, flowing liquid medium has explicit advantages, such as a higher damage threshold compared to solid-state sources and more efficient ionization process compared to gases. Here we report systematic study of efficient generation of terahertz radiation in flat liquid jets under sub-picosecond single-color optical excitation. We demonstrate how medium parameters such as molecular density, ionization energy and linear absorption contribute to the terahertz emission from the flat liquid jets. Our simulation and experimental measurements reveal that the terahertz energy has quasi-quadratic dependence on the optical excitation pulse energy. Moreover, the optimal pump pulse duration, which depends on the thickness of the jet is theoretically predicted and experimentally confirmed. The obtained optical-to-terahertz energy conversion efficiency is more than 0.05%. It is comparable to the commonly used optical rectification in most of electro-optical crystals and two-color air filamentation. These results, significantly advancing prior research, can be successfully applied to create a new alternative source of terahertz radiation.

Retrograde Regulation by the Viral Protein Kinase Epigenetically Sustains the Epstein-Barr Virus Latency-to-Lytic Switch To Augment Virus Production.

Herpesviruses are ubiquitous, and infection by some, like Epstein-Barr virus (EBV), is nearly universal. To persist, EBV must periodically switch from a latent to a replicative/lytic phase. This productive phase is responsible for most herpesvirus-associated diseases. EBV encodes a latency-to-lytic switch protein which, upon activation, sets off a vectorially constrained cascade of gene expression that results in production of infectious virus. While triggering expression of the switch protein ZEBRA is essential to lytic cycle entry, sustaining its expression is equally important to avoid premature termination of the lytic cascade. We report that the viral protein kinase (vPK), encoded by a gene that is kinetically downstream of the lytic switch, sustains expression of ZEBRA, amplifies the lytic cascade, increasing virus production, and, importantly, prevents the abortive lytic cycle. We find that vPK, through a noncanonical site phosphorylation, activates the cellular phosphatidylinositol 3-kinase-related kinase ATM to cause phosphorylation of the heterochromatin enforcer KAP1/TRIM28 even in the absence of EBV genomes or other EBV proteins. Phosphorylation of KAP1 renders it unable to restrain ZEBRA, thereby further derepressing and sustaining its expression to culminate in virus production. This partnership with a host kinase and a transcriptional corepressor enables retrograde regulation by vPK of ZEBRA, an observation that is counter to the unidirectional regulation of gene expression reminiscent of most DNA viruses.IMPORTANCE Herpesviruses infect nearly all humans and persist quiescently for the life of the host. These viruses intermittently activate into the lytic phase to produce infectious virus, thereby causing disease. To ensure that lytic activation is not prematurely terminated, expression of the virally encoded lytic switch protein needs to be sustained. In studying Epstein-Barr virus, one of the most prevalent human herpesviruses that also causes cancer, we have discovered that a viral kinase activated by the viral lytic switch protein partners with a cellular kinase to deactivate a silencer of the lytic switch protein, thereby providing a positive feedback loop to ensure successful completion of the viral productive phase. Our findings highlight key nodes of interaction between the host and virus that could be exploited to treat lytic phase-associated diseases by terminating the lytic phase or kill cancer cells harboring herpesviruses by accelerating the completion of the lytic cascade.

Methodical inaccuracy of the Z-scan method for few-cycle terahertz pulses.

Modern sources of THz radiation generate high-intensity pulses allowing to observe nonlinear effects in this spectral range. To describe many nonlinear effects theoretically, it is necessary to know the nonlinear refractive index coefficient of optical materials. The work studies the applicability of the Z-scan method to determine the nonlinear refractive index coefficient in the THz frequency range for few-cycle pulses. We have discussed the correctness of the known Z-scan method for calculating the nonlinear refractive index coefficient for broadband THz radiation regarding number of cycles pulses have. We have demonstrated that the error in determining the nonlinear refractive index coefficient is always greater than 70% for true single-cycle pulses. With the increase in the number of oscillations to the measurement error shows strong dependence on the sample thickness and can vary from 2% to 90% regarding the parameters chosen. The fact that such radiation dispersion length is commensurate with the nonlinear length or even less than the latter results in the discrepancy mentioned. It is demonstrated that the decrease in the sample thickness leads to the reduction of the nonlinear refractive index coefficient determination error, and this error is <2% when the ratio between the sample thickness and the pulse longitudinal spatial size is ≤1. This can relate to the fact that the nonlinear effects in such a thin sample occur faster than the dispersion ones.

High Kerr nonlinearity of water in THz spectral range.

The values of the nonlinear refractive index coefficient for various materials in the terahertz frequency range exceed the ones in both visible and NIR ranges by several orders of magnitude. This allows to create nonlinear switches, modulators, systems requiring lower control energies in the terahertz frequency range. We report the direct measurement of the nonlinear refractive index coefficient of liquid water by using the Z-scan method with broadband pulsed THz beam. Our experimental result shows that nonlinear refractive index coefficient in water is positive and can be as large as 7×10-10 cm2/W in the THz frequency range, which exceeds the values for the visible and NIR ranges by 6 orders of magnitude. To estimate n2, we use the theoretical model that takes into account ionic vibrational contribution to the third-order susceptibility. We show that the origins of the nonlinearity observed are the anharmonicity of molecular vibrations.

A Roberts Syndrome Individual With Differential Genotoxin Sensitivity and a DNA Damage Response Defect.

PURPOSE: Roberts syndrome (RBS) is a rare, recessively transmitted developmental disorder characterized by growth retardation, craniofacial abnormalities, and truncation of limbs. All affected individuals to date have mutations in the ESCO2 (establishment of cohesion 2) gene, a key regulator of the cohesin complex, which is involved in sister chromatid cohesion and DNA double-strand break (DSB) repair. Here we characterize DNA damage responses (DDRs) for the first time in an RBS-affected family. METHODS AND MATERIALS: Lymphoblastoid cell lines were established from an RBS family, including the proband and parents carrying ESCO2 mutations. Various DDR assays were performed on these cells, including cell survival, chromosome break, and apoptosis assays; checkpoint activation indicators; and measures of DNA breakage and repair. RESULTS: Cells derived from the RBS-affected individual showed sensitivity to ionizing radiation (IR) and mitomycin C-induced DNA damage. In this ESCO2 compound heterozygote, other DDRs were also defective, including enhanced IR-induced clastogenicity and apoptosis; increased DNA DSB induction; and a reduced capacity for repairing IR-induced DNA DSBs, as measured by γ-H2AX foci and the comet assay. CONCLUSIONS: In addition to its developmental features, RBS can be, like ataxia telangiectasia, considered a DDR-defective syndrome, which contributes to its cellular, molecular, and clinical phenotype.

The Results of the Combine Treatment of Patients with Liver Bilobar Metastases from Colorectal Cancer Using Radiofrequency Ablation.

Colorectal cancer (CRC) is the third most common cancer worldwide. The mortality from CRC remains very high. The main cause of such a high mortality is a disseminate process with the appearance of distant metastases. In this regard, the treatment of metastatic lesions is recognized as an important trend in modern oncology. The program of study included 176 patients with colorectal cancer after primary tumor removal with the malignant progression-multiple (more than 4) bilobar liver metastases. The research was organized in Samara Regional Oncology Centre from 2001 to 2014. By the treatment method, patients were divided into two groups. Main group got the combined (chemotherapy + radiofrequency ablation (RFA)) treatment (n = 98). In control group, only chemotherapy was applied (n = 78). One-, two-, and three-year OS were 73.5, 25.1, and 7.2% in the main group and 39.6, 6.3, and 2.1% in the control group. The RFA application allowed us to reach the index of 4-year survival 1.8% in the main group, while we received only 2.1 of 3-year survival in the control group. The OS median reached 18 months in the main group and 11 months in the control group. So, the OS curves in two comparing groups were significantly different according to statistics (log-rank test 3.77, р = 0.000). The application of RFA in combination with chemotherapy in the treatment of bilobar metastasis colorectal cancer allows to improve the performance of disease-free survival and overall survival significantly, compared with the group of patients who received only chemotherapy.

Identification of ATM Protein Kinase Phosphorylation Sites by Mass Spectrometry.

ATM (ataxia-telangiectasia mutated) protein kinase is a key regulator of cellular responses to DNA damage and oxidative stress. DNA damage triggers complex cascade of signaling events leading to numerous posttranslational modification on multitude of proteins. Understanding the regulation of ATM kinase is therefore critical not only for understanding the human genetic disorder ataxia-telangiectasia and potential treatment strategies, but essential for deciphering physiological responses of cells to stress. These responses play an important role in carcinogenesis, neurodegeneration, and aging. We focus here on the identification of DNA damage inducible ATM phosphorylation sites to understand the importance of autophosphorylation in the mechanism of ATM kinase activation. We demonstrate the utility of using immunoprecipitated ATM in quantitative LC-MS/MS workflow with stable isotope dimethyl labeling of ATM peptides for identification of phosphorylation sites.

Lentiviral Reprogramming of A-T Patient Fibroblasts to Induced Pluripotent Stem Cells.

Reprogramming of cells enables generation of pluripotent stem cells and resulting progeny through directed differentiation, making this technology an invaluable tool for the study of human development and disease. Reprogramming occurs with a wide range of efficiency, a culmination of intrinsic and extrinsic factors including the tissue of origin, the passage number and culture history of the target cells. Another major factor affecting reprogramming is the methodology used and the quality of the reprogramming process itself, including for conventional viral-based approaches viral titer and subsequent viral transduction efficiency, including downstream transgene insertion and stoichiometry. Genetic background is an important parameter affecting the efficiency of the reprogramming process with reports that cells from individuals harboring specific mutations are more difficult to reprogram than control counterparts.Ataxia-Telangiectasia (A-T) fibroblasts underwent reprogramming at reduced efficiency in contrast to their controls. To optimize reprogramming of fibroblasts from patients with A-T, we examined the response of A-T cells to various cell culture conditions after lentiviral transduction with reprogramming factors Oc4/Sox2 (pSIN4-EF2-O2S) and Klf4/c-Myc (pSIN4-CMV-K2M). Parameters included media type (KSR or serum-containing DMEM), treatment with a p53 inhibitor (small-molecule cyclic pifithrin-α), and either a low or high concentration of bFGF. Post-transduction, equivalent numbers of cells from heterozygote and homozygote patients were plated and assessed at regular intervals for survival and proliferation. Our findings indicate that A-T cells responded favorably to the addition of FCS and gradual weaning away from their native media into KSR-containing stem cell media that produced suitable conditions for their reprogramming. We examined a range of properties to identify and isolate good quality iPSCs including the expression status of important stem cell transcription factors/surface proteins, methylation levels at stem cell associated regulatory loci, persistence of transgenes, karyotype status, and teratoma-forming ability.